CA1308508C - Heat-curable silicone compositions comprising fumarate cure-control additive and use thereof - Google Patents
Heat-curable silicone compositions comprising fumarate cure-control additive and use thereofInfo
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- CA1308508C CA1308508C CA 566102 CA566102A CA1308508C CA 1308508 C CA1308508 C CA 1308508C CA 566102 CA566102 CA 566102 CA 566102 A CA566102 A CA 566102A CA 1308508 C CA1308508 C CA 1308508C
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C08L83/04—Polysiloxanes
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/10—Esters; Ether-esters
- C08K5/11—Esters; Ether-esters of acyclic polycarboxylic acids
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31652—Of asbestos
- Y10T428/31663—As siloxane, silicone or silane
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Abstract
HEAT-CURABLE SILICONE COMPOSITIONS COMPRISING
FUMARATE CURE-CONTROL ADDITIVE AND USE THEREOF
ABSTRACT
Compositions which cure by a platinum-catalyzed reaction between silicon-bonded hydrogen atoms and silicon-bonded, aliphatically unsaturated hydrocarbon radicals have improved pot-life and cure-rate characteristics when a catalyst-inhibiting amount of a diorgano fumarate compound is added to the composition. Solventless coating compositions containing a dialkyl fumarate, a methylhydrogenpolysiloxane and a methylpolysiloxane bearing hexenyl radicals are particularly useful as adhesive-release coatings for acrylic-based pressure sensitive adhesives, applied in-line.
FUMARATE CURE-CONTROL ADDITIVE AND USE THEREOF
ABSTRACT
Compositions which cure by a platinum-catalyzed reaction between silicon-bonded hydrogen atoms and silicon-bonded, aliphatically unsaturated hydrocarbon radicals have improved pot-life and cure-rate characteristics when a catalyst-inhibiting amount of a diorgano fumarate compound is added to the composition. Solventless coating compositions containing a dialkyl fumarate, a methylhydrogenpolysiloxane and a methylpolysiloxane bearing hexenyl radicals are particularly useful as adhesive-release coatings for acrylic-based pressure sensitive adhesives, applied in-line.
Description
130850~3 H~AT-CURABLE SILICONE COMPOSITIONS COMPRISING
FUMARATE CURE-CONTROL ADDITIVE AND USE THEREOF
The pre~ent invention relate.q ~ener~lly to heat-curable, sili~on-containing compositiGns. More specifically, this invention relates to compositions which cure by way of a platinum-catalyzed reaction of silicon-bonded olefinic hydrocarbon radicals with ~ilicon-bonded hydrogen atoms, wherein the room temperature catalytic activity of the platinum-containing catalyst has been inhibited by the presence of an inhibitor component who3e inhibiting action can be overcome by heating.
Organos,ilicon compositions in which a platinum-containin~ catalyst is inhibited in its cure-promoting activity at room temperature by the presence of a catalyst inhibitor are well known in the organosilicon art. Examples of compositions having platinum catalyst inhibitors include those containing unsaturated organic compounds; such as ethylenically or aromatically unsaturated amides, U.S. Patent No. 4,337,332; acetylenic compounds, U.S. Patent No. 3,445,420; ethylenically unsaturated isocyanates, U.S.
Patent No. 3,882,083; olefinic siloxanes, U.S. Patent No.
3,989,667; and con~ugated ene-ynes, V.S. Patent Nos. 4,465,818 and 4,472,563; other organic compounds such as hydroperoxides, sulfoxides, amines, phosphines, phosphites and nitrile~; and various metal salts.
More relevantly, the unsaturated hydrocarbon diester inhibitors of U.S. Patent No. 4,Z56,870, such as diallyl or diethyl maleate, and the bis-hydrocarbonoxyalkyl maleate inhibitors of U.S. Patent No. 4,562,096, such as bis-(2-methoxyisopropyl) maleate, have been found to be effective for delaying or preventing the room temperature cure of organosilicon compositions which cure by way of a ~308S08 platinum group metal catalyzed reaction. However, the cure time and/or the cure temperature of these maleate-inhibited compositions are/is undesirably increased by the use of these inhibitors.
This problem of increased cure time and/or cure temperature in an inhibited platinum-catalyzed system is of particular significance for applications where the organo-silicon composition is used to rapidly coat a substrate, such as i8 practiced in the adhesive release coating art.
In the coating arts, such as the paper coating art, the coating composition that iq used to coat a substrate should not cure to the extent that its viscosity has increased substantially before it has been applied to the substrate; however, it should rapidly cure thereafter, preferably with only a moderate amount of added energy. This means that the coating compositions preferably should not experience a doubling of its viscosity at ambient temperature for as long as eight hours, but should cure rapidly, at moderately increased temperature, to such an extent that the coated substrate can be further processed.
Furthermore, when the cured coating composition is to be immediately coated with a reactive adhesive, such as an acrylic-based pressure-sensitive adhesive composition, the release coating must be fully cured before the adhesive composition is applied in order to minimize the bonding of the adhesive to the partially cured silicone coating, a phenomenon known as "acrylic weld".
Compositions having improved curing characteristics, and little or no acrylic weld, have been disclosed in U.S. Patent No. 4,609,574. The improvements of these compo9itions have been realized by the use of higher alkenyl radicals, such as hexenyl, instead of the usual vinyl radical, as the reactive olefinic hydrocarbon radical.
1~0850~3 However, even in these improved compositions, the cure rate of the higher al~enyl reaction site has no~ been fully utilized becau3e the catalyst inhibitor is excessively active at elevated temperatures.
The que~t f~r the ideal pl~tinum catalyst inhibitor in silicon-containing compositions, particularly coating composition~, continue~.
It is an ob~ect of this invention to provide improved ~urable organosilicon compositions. It is also an object of this invention to provide organopolysiloxane compositions which do not cure at room temperature for long periods of time but which cure rapidly when heated to moderately elevated temperatures. It is a particular object of the present invention to provide liquid organopolysiloxane coating compositions which remain liquid for hours at temperatures up to 104~F. (40C.) but which cure within 90 second~ when coated onto a substrate and heated to a temperature of as low as 180F. (82C.). It is an additional ob~ect of this invention to provide curable compositions for adhesive release which do not experience acrylic weld.
These objectc, and others which will occur ~o one of ortinary ~kill in the curable organosilicon composition art upon considering the following disclosure and appended claims, are obtained by the present invention which, briefly stated, comprises a curable organosilicon composition comprising a component having silicon-bonded hydrogen atoms, a component having silicon-bonded olefinic hydrocarbon radicals reactive therewith, a platinum-containing catalyst and an effective amount of a diorgano fumarate cure-control, i.e. catalyst inhibitor, component.
Surprisingly, the room temperature cure times of the organopolysiloxane coating compositions of this invention are adequately long, and their cure times at elevated -4- 130~508 ~emperature are advantageously brief, that they are useful in fast-paced coating operations, su~h as adhesive release coating operations wherein the cured coating is further coated in-line, i.e., immediately after being cured, with an acrylic-based adhesive.
The present invention relates to a curable composition comprising (A) an organosilicon compound having an average of from one to three ~ilicon-bonded monovalent radicals per silicon atom selected from tha group consisting of hydrocarbon and halohydrocarbon radicals, there being an average of at least two of said monovalent radicals, per molecule of Component (A), selected from the group consisting of olefinic hydrocarbon radicals, the remaining silicon valences thereof being satisfied by divalent radicals free of aliphatic unsaturation selected from the group consisting of oxygen atoms, hydrocarbon radicals, hydrocarbon ether radicals, halohydrocarbon ether radicals and halohydrocarbon radicals, said divalent radicals linking silicon atoms, (B) an organohydrogensilicon compound containing at least two silicon-bonded hydrogen atoms per molecule thereof and an average of from one to two silicon-bonded monovalent radicals free of aliphatic unsaturation, per silicon atom, selected from the group consisting of hydrocarbon and halohydrocarbon radicals, the remaining silicon valences thereof being satisfied by divalent radicals free of aliphatic unsaturation selected from the group consisting of oxygen atoms, hydrocarbon radicals, hydrocarbon ether radicals, halo-hydrocarbon ether radicals and halohydrocarbon radicals, said divalent radicals linking silicon atoms, (C) an amount of a platinum-containing catalyst sufficient to accelerate a reaction of said silicon-bonded olefinic hydrocarbon radicals with said ~ilicon-bonded hydrogen atoms at room temperature, and (D) an amount of an inhibitor compound for the platinum-containing catalyst sufficient to retard said reaction at room temperature but insufficient to prevent said re ction at elevated temperature, said inhibitor compound ha~ing the formula o RlO(DO)aC H
C=C
H C(OD)aORl wherein each Rl denotes, independently, a monovalent hydro-carbon radical having from 1 to 6 carbon atoms, each D
denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of 0 or 1, the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/100 to 100/1.
Herein the term "curable", as applied to compositions of this invention, generally denotes a chemical change which leads to an increase in the molecular weight of one or more of the components in the composition. Said increase in molecular weight, typically, is accompanied by an increase in the viscosity of the curable composition. For the coating compositions of this invention the term curable denotes a change in the state of the composition from a liquid to a ~olid. For coating compositions of this invention which are to be used as adhesive-release coatings, the term "curable" has a more detailed meaning which encompasses the properties of smear, migration and rub-off of the coating, as delineated below.
The curing of the compositions of this invention is accomplished by hydrosilylation, i.e., a platinum-catalyzed addition reaction between silicon-bonded olefinic hydrocarbon radicals of Component (A) and silicon-bonded hydrogen atoms of Component (B).
~ roadly stated, Component (A) of the compositions of this invention can be any organosilicon compound containing two or more silicon atoms linked by divalent radicals and containing an average of from 1 to 3 silicon-bonded monovalent radicals per silicon, with the proviso that the organosilicon compound contains at least two silicon-bonded olefinic hydrocarbon radicals. This component can be a solid or a liquid, freely flowing or gum-like.
Examples of said divalent radicals linking silicon atoms in Component (A) include oxygen atoms, which provide siloxane bonds, and aliphatically saturated hydrocarbon, hydrocarbon ether, halohydrocarbon ether and halohydrocarbon radicals which provide silcarbane bonds. The divalent radicals can be the same or different, as desired.
Examples of suitable divalent hydrocarbon radicals include any alkylene radical, such as -CH2-, -CH2CH2-, CH (CH )CH- -(CH2)4-, -CH2CH(CH3)CH2 ~ ( 2 6 -(CH2)18-; cycloal~ylene radical, such as cyclohexylene;
arylene ratical, such as phenylene and combinations of hydrocarbon radicals, such as benzylene, i.e. -C6H4CYA2-.
Examples of suitable divalent halohydrocarbon radicals include any divalent hydrocarbon radical wherein one or more hydrogen atoms have been replaced by halogen, such as fluorine, chlorine or bromine. Preferable divalent halo-hydrocarbon radicals have the formula -CH2CH2CnF2nCH2CH2-wherein n has a value of from 1 to 10 such as, for example,ru ru r~ r~ ru ru - v~l2V~l2vr 2v~ 2V' 2 2 Examples of suitable divalent hydrocarbon ether radicals and halohydrocarbon ether radicals include -7- 1308~08 -cH CH2CH2CH2-' ~CH2CH2CF2CF2C~2CH2 ' 2 2 2 2 2 2 and -c6~4-o-C6H4-Examples of said monovalent radicals in Component(A) include halohydrocarbon radicals free of aliphatic unsaturation and hydrocarbon radicals.
Examples of suitable monovalent hydrocarbon radicals include alkyl radicals, such as CH3-, CH3CH2-, 3~2 ' 8H17 ~ ClOH21- and C20H4l-; cycloaliphatic radicals, such as cyclohexyl; aryl radicals, such as phenyl, tolyl, xylyl, anthracyl and xenyl; aralkyl radicals, such as benzyl and 2-phenylethyl; and olefinic hydrocarbon radicals, such as vinyl, allyl, methallyl, 3-butenyl, 5-hexenyl, 7-octenyl, cyclohexenyl and styryl. Alkenyl radicals are preferably terminally unsaturated. Of the higher alkenyl radicals, those selected from the group consisting of 5-hexenyl, 7-octenyl, and 9-decenyl are preferred because of the more ready availability of the alpha,omega-dienes used to prepare the alkenylsiloxanes. Highly preferred monovalent hydrocarbon radical for the silicon-containing components of the compositions of this invention are methyl, phenyl, vinyl and 5-hexenyl.
Examples of suitable aliphatically saturated monovalent halohydrocarbon radicals include any monovalent hydrocarbon radical which is free of aliphatic unsaturation and has at least one of its hydrogen atoms replaced with halogen, such as fluorine, chlorine or bromine. Preferable monovalent halohydrocarbon radicals have the formula CnF2n+lCH2CH2- wherein n has a value of from 1 to 10, such as, for example, CF3CH2CH2 and C4F9CH2CH2 .
Component (A) of the compositions of this invention is typically an organopolysiloxane having the average unit formula Rc ~iO(4_C)/2 wherein R2 denotes said monovalent radicals, delineated and limited above, and c has a value of from 1 to 3, such as 1.2, 1.9, 2.0, 2.1, 2.4 and 3Ø
Suitable siloxane units in the organopolysiloxanes having the above average unit formula have the formulae R32SiO1~2, R2 SiO2/2, R SiO3/2 and SiO4/2. Said siloxane units can be combined in any molecular arrangement such as linear, branched, cyclic and combinations thereof, to provide organo-polysiloxanes that are useful as component (A).
A preferred organopolysiloxane Component (A) for the composition of this invention is a substantially linear organopolysiloxane having the formula XR2SiO(XRSiO)XSiR2X.
By substantially linear, it is meant that the component contains no more than trace amounts of silicon atoms bearin~
3 or 4 siloxane linkaees. It is to be understood that the term sub~tantially linear encompasses organopolysiloxanes which can contain up to about 15 percent by weight cyclo-polysiloxanes which are frequently co-produced with the linear or~anopolysiloxanes.
In the formula shown immediately above, each R
denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic un~aturation and having from l to 20 carbon atoms, as exemplified above. The ~everal R radicals can be identical or different, as desired. Additionally, each X
denotes an R radical or an olefinic hydrocarbon radical having from 2 to 12 carbon atoms, as exemplified above. Of course, at least two X radicals are olefinic hydrocarbon radicals.
The value of the subscript x in the above formula i9 such that the linear organopolysiloxane (A) has a viscosity at 25~C. of at least 25 millipascal-seconds (25 centipoise). The exact value of x that is needed to provide a viscosity value falling within said limit depends upon the identity of the X and R radicals; however, for hydrocarbyl-~9~ 130~508 terminated polydimethylsiloxane x will have a value of atleast about 25.
In terms of preferred monovalent hydrocarbon radicals, noted above, example~ of preferred linear organo-polysiloxanes of the above formula which are suitable as Component (A3 for the composition of this invention include PhMeViSiO(Me2SiO)10OSiPhMeVi, HexMe2SiO tMe2SiO ) 150SiMe2Hex 9 YiMe2SiO(Me2SiO)lOO(HeXMeSiO)2SiMe2Vi, ViMe2sio(Me2sio)o 95x(MeViSi)O.05xsiMe2v HexMe2SiO(Me2SiO)lso(HeXMesi)4siMe2 Me3SiO(Me2siO)o gxtMevisio)o.lxSiMe3' Me3SiO(Me2SiO)1OO(MeHexSiO~8SiMe3, (Me2siO)0.93X(Mephsio)o 07xsiphMevi and viMe2si(Me2si)xsiMe2vi wherein Me, Vi, Hex and Ph denote methyl, vinyl, 5-hexenyl and phenyl, respectively.
For the coating composition of this invention, it i8 highly preferred that the linear organopolysiloxanes (A) have the formula XMe2SiO(Me2SiO)b(MeXSiO)dSiMe2X wherein X is as noted above and the sum of b plus d is equal to x, also noted above. The values of the subscripts b and d can each be zero or Breater; however, the val~se of d is typically less than O.lb such as zero, 0.02b or 0.08b. Examples of highly preferred linear organopolysiloxanes (A) for adhesi.ve-release coating compositions of this invention include Me3SiO(Me2SiO)b(MeHexSiO)dSiMe Me3SiO(tle2SiO)b(MeViSiO)dSiMe3 , HexMe2SiO(Me2SiO)b(MeHexSiO)dSiMe2Hex and ViMe2SiO(Me2,SiO)b(MeViSiO)dSiMe2Vi.
In a preferred embodiment of the present invention, wherein the curable composition, preferably solventless, is used to coat a solid substrate, such as paper, with an 130!350~
adhesive-releasing coating, the value of b plus d in the highly preferred organopolysiloxane (A) is sufficient to provide a viscosity at Z5C. for the Component (A) of at least 100 mPa-s, such a~ from about 100 mPa-s to about 100 Pa-s, preferably from about 100 mPa s to 10 Pa- s and, most preferably, from 100 mPa-~ to 5 Pa-s; ~aid viscosities corresponding approximately to values of b + d of at least 60, such as from 6~ to 1000, preferably to 520 and, most preferably, to 420.
Broadly stated, Component (B) of the compositions of this invention can be any organohydrogensilicon compound which is free of aliphatic unsaturation and contains two or more silicon atoms linked by divalent radicals, an average of from one to two silicon-bonded monovalent radicals per silicon atom and an average of at least two, and preferably three or more, silicon-bonted hydrogen atoms per molecule thereof.
Examples of said divalent radicals linking silicon atoms in Component (B) are as delineated above for Component (A), including preferred examples. As with Component (A), the divalent radicals within Component (B) can be identical or different, as desired. Furthermore, the divalent radicals that are present in Component (B) can, but need not, be the same as the divalent radicals that are present in Component (A).
Examples of said monovalent radicals in Component (B) include hydrocarbon and halohydrocarbon radicals, as delineated above for Component (A), including preferred examples, which are free of aliphatic unsaturation. The monovalent radicals that are present in Component (B) can, but need not, be the same ag the monovalent radicals that are present in Component (A).
.308S0~
component (B) must contain an average of at least two silicon-bonded hydrogen atoms per molecule thereof.
Preferably, component (B) contains an average of three or more silicon-bonded hydrogen atoms such as, fos example, 5, 10, 20, 40 and more.
component (~) typically has a 100 percen~ siloxane structure, i.e., an organohydrogenpolysiloxane structure having the average unit formula Re3HfSiO~4 e f)/2 wherein R3 denotes said monovalent radical free of aliphatic unsaturation, f has a value of from ~reater than 0 to 1, such as 0.001, 0.01, 0.1 and 1.0, and the sum of e plus f has a value of from 1 to Z, such as 1.2, 1.9 and ZØ
Suitable siloxane units in ~he organohydrogenpoly-siloxanes having the average unit formula immediately above have the formulae R3 Si0l/2~ R2 ~Sil/2' R2 Si2/2' R HSiO2/2, R SiO3/2, HSiO3/2 and SiO4/2. Said siloxane units can be combined in any molecular arrangement sLlch as linear, branched, cyclic and combinations thereof, to provide organohydrogenpolysiloxanes that are useful aq Component (B).
A preferred organohydrogenpolysiloxane Component (B) for the composition~ of this invention is a substantially linear organohydrogenpolysiloxane having the formula YR2SiO(YRSiO)ySiR2Y wherein each R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation and having Prom 1 to 20 carbon atoms, as exemplified above. The several R radicals can be identical or different, as desired. Additionally, each Y denotes a hydrogen atom or an R radical. Of course, at least two Y
radicals must be hydrogen atoms.
The value of the subscript y is not critical;
however, it is preferably such that the organohydrogenpoly-siloxane Component (B3 has a viscosity at 25C. of up to 100 millipascal-seconds. The exact value of y needed to provide a vi~co~ity value falling within ~aid limits depends upon the number and identity of the R radicals; however, for organo-hydrogenpolysiloxanes containinK only methyl radicals as R
radicals y will have a value of from about O to about 100.
In terms of preferred monovalent hydrocarbon radicals, noted above, examples of linear organohydrogen-polysiloxanes of the above formula which are suitable as Component (B) for the compositions of this invention include HMe2SiO(Me2SiO)ySiMe2H, Me3SiO(MeHSiO)ySiMe3, HMe2SiO(Me2SiO)0 5y(MeHSiO)0 5ySiMe2H, HMe2Si(Me2SiO)0 5y(MePhSiO)0 1y(MeHSiO)0 4 SiMe2H, Me3SiO(Me2SiO)0 4y(MeHSiO)0 6ySiMe3, (MeHSiO)y, (HMe2SiO)4Si and MeSi(OSiMe2H)3.
Highly preferred linear organohydrogenpoly9iloxane ~B) for the coating composition8 of this invention have the for~ula YMe2SiO(Me2SiO)p(MeYSiO)qSiMe2Y wherein Y denotes a hydrogen atom or an R radical, free of aliphatic unsaturation. Again, an average of at least two Y radicals per molecule of Component (B) must be hydrogen atoms. The subscripts p and q can have average values of zero or more and the sum of p plu9 q has a value equal to y, noted above.
For the adhesive-releasing coating compositions of this invention, Y should be H or methyl. A particularly effective organohydrogenpolysiloxane component (B) for the compositions of this invention comprises a mixture of two compounds having the formulae Me3SiO(MeHSiO)35SiMe3 and Me3SiO(Me2SiO)3(MeHSiO)sSiMe3-The amount~ of Components (A) and (B) that are used in the compositions of this invention are not narrowly limited. Said amounts, expressed in terms of the ratio of the number of silicon-bonded hydrogen atoms of Component (B) to the number of silicon-bonded olefinic hydrocarbon radicals of Component (A), as is typically done, are sufiicient to -13- ~30850~
provide a value for said ratio of from 1/lOO to 100/l, usually from l/ZO to 20/1, and preferably from 1/2 to 20/1.
For the liquid ~oating compo~itions of this in~ention which are to be used in the coating method of this invention, hereinbelow delineated, the value of said ratio should have a value of from 1/2 to 1.5/1, and preferably about 1/1.
Organosilicon polymers are, of course, well known in the orga~osilic~n art. Organopolysiloxanes are clearly the most significant and most widely used form of organo-silicon polymers in the art, and in this invention; many are commercially prepared. The preparation of the organosilicon components that are used in the compositions of this invention i~ well documented and needs no intensive delineation herein.
Briefly, organopolysiloxanes are typically prepared by way of hydrolysis and condensation of hydrolyzable silanes such as Me2SiC12, Me3SiCl, MeSiC13, SiC14, Me2Si(OMe)2, MeSi(OMe)3 and Si(OCH2CH3)4 or by way of acid- or alkali-catalyzed siloxane equilibration of suitable siloxane precursors such as (Me2SiO)4 and Me3SiOSiMe3, which themselves are prepared by way of said hydrolysis and condensation reactions.
Organopolysiloxane Component (A) can be prepared as noted above with the proviso that a silane or siloxane containing at least one silicon-bonded olefinic hydrocarbon radical i~ used, alone or in con~unction with other silanes or siloxanes, in sufficient amount to provide the necessary number of olefinic hydrocarbon radicals in the organopoly-siloxane. Examples of olefinic hydrocarbon radical-containing silanes or siloxanes include, but are not limited to, ViMe2SiCl, HexMe2SiCl, MeViSiC12, MeHexSiC12, ViSiC13, HexSiCl3, (MeViSiO)4, HexMe2SiOSiMe2Hex and ViMe2SiOSiMe2Vi.
-14- i308508 It is usually preferred t~ prepare olefini~
siloxanes by hydrolyzing a readily hydrolyzable silane, such as 5-hexenyl- or ~inyl-methyldichlorosilane, in excess water and then equilibrating the resulting hydrolyzate with cyclo-polydimethylsiloxanes and a siloxane oligomer containing triorganosiloxane end groups, using a base cataly~t such as KOH. Howev~r, it is believed that olefinic polydiorgano-siloxanes may also be advantageously prepared in a one-step acid-catalyzed process wherein the hydrolyzable silane is hydrolyzed and simultaneously equilibrated with cyclopolydi-methyl~iloxanes and siloxane oligomer containing end groups.
Alternatively, known polyorganohydrogensiloxanes bearing reactive SiH group~ can be reacted with an alpha,omega-diene, such as 1,5-hexadiene, to prepare higher alkenyl-substituted organopolysiloxanes. It should be noted that linear siloxanes produced by equilibration procedures may contain small amounts such as 0 to 15 weight percent of cyclopolydiorganosiloxanes which may be volatile at temperatures up to 150C. For the purpose9 of this invention either siloxanes that still contain the small amounts of cyclics, or siloxanes from which the co-produced cyclics have been removed by volatilization may be used.
Organohydrogenpolysiloxane Component (B) can be prepared as noted above with the proviso that a silane or siloxane containing at least one silicon-bonded hydrogen atom, instead of olefinic hydrocarbon radical, is used, alone or in combination with other silanes or siloxanes, in sufficient amount to provide the necessary number of silicon-bonded hydrogen atoms in the organohydrogenpoly-siloxane. Example~ of hydrogen atom-containing silanes or siloxanes include, but are not limited to, HMe2SiCl, HMeSiC12, HSiC13, HMe2SiOSiMe2H and (MeHSiO)4. Component (~) -15- ~ 3 0 ~ 5 O 8 is preferably prepared under nonalkaline conditions to minimize hydrolysis of the SiH linkage.
Organosilicon polymers having a mix of silcarbane and siloxsne structure can be prepared, for example, from monomeric 9pecies that have nonoxygen divalent radicals, such as Ol/2Me2SiCH2CH2Me2SiOl/2 or ClMe2sic6H4siMe2cl~ uging standard hydrolysis and condensation reactions, noted above, and incorporating one or more of the olefinic hydrocarbon radicals or hydrogen atom-containing silanes or siloxanes noted above, and other silanes or siloxanes, as desired.
Organosilicon polymers which contain no siloxane bonds can be prepared, for example, by a hydrosilylation reaction between silanes or silcarbanes bearing silicon-bonded olefinically unsaturated hydrocarbon radical~, such a~
Vi2SiMe2 or ViMe2SiC6H4SiMe2Vi and silanes or silcarbanes bearing silicon-bonded hydrogen atoms, such as H2SiMe2 or l~e~2SiC6H4SiMe2H .
Other suitable methods for preparing the organo-silicon components that are used in the composition~ of this invention also occur in the organosilicon art.
Broadly stated, Component (C) of the composition of this invention is a catalyst component which facilitates the reaction of the silicon-bonded hydrogen atom~ of Component (~) with the ~ilicon-bonded olefinic hydrocarbon radicals of Component (A) and can be any platinum-containing catalyst component. For example, Component (C~ can be platinum metal;
a carrier, such as silica gel or powdered charcoal, bearing Flstinum metal; or a compound or complex of a platinum metal.
A typical platinum-containing catalyst component in the organopolysiloxane compositions of this invention is any form of chloroplatinic acid, such as, for example, the readily available hexahydrate form or the anhydrous form, because of its easy dispersibility in organosiloxane system~.
-16- 1 3085~8 A particularly useful form of chloroplatinic acid i8 that composition obtained when it is reacted with an aliphatically unsaturated organosilicon compound such as divinyltetramethyldisiloxane, as disclosed by U.S. Patent No.
3,419,593.
The amount of platinum-containing cataly~t component that is used in the compositions of this invention is not narrowly limited a~ long as there is a sufficient amount to accelerate a room temperature reaction between the silicon-bonded hydrogen atom~ of Component (B) with the silicon-bonded olefinic hydrocarbon radicals of Component (A). The exact nece~sary amount of said catalyst component will depend upon the particular catalyst and i9 not easily predictable. However, for chloroplatinic acid said amount can be as low as one part by weieht of platinum for every one million parts by weight of organosilicon Components (A) plus (B). Preferably, said amount is at least 10 parts by weight, on the same basis.
For compositions of this invention which are to be used in the coating method of this invention the amount of platinum-containing catalyst component to be used is preferably sufficient to provide from 10 to SOO parts by weight platinum per one million parts by weight of organo-polysiloxane Components (A) plus (B).
Broadly stated, Component (D) of the compositions of this invention is any diorgano fumarate having the formula trans-RlO(DO)a(O)CC~=CHC(O)(OD)aORl. The diorgano fumarate can be a dihydrocarbon fumarate or a dihydrocarbonoxyalkyl fumarate. That is to say, the value of subscript a in the formula immediately above can have a value equal to zero or 1. The individual value~ of a can be identical or different, as desired.
-17- 1 3 0 8 ~ ~3 The hydrocarbon radical, i.e., the ~1 radical, in the above formula has from 1 to 6 carbon atoms and can be, for example, an al~yl radical such as methyl, ethyl, propyl, isopropyl ~ butyl, pentyl or hexyl; an aryl radical such as phenyl; an alkenyl radical such as vinyl or allyl; or a cyclohydrocarbon radical such as cyclohe~yl.
In the above formula for the diorgano fumarate each D denotes, independently, an alkylene radical having from 2 to 4 carbon atoms such as -CH2CH2-, -CH2(CH3)CH-, 2 2 H2 ~ CH2CH2CH2cH2-~ -CH2(CH3CH2)CH- and -CH2CH2(CH3)CH-. The indi~idual D radicals can be identical or different, a~ desired.
In terms of ease of preparation and inhibiting effect in the compositions of this inventiGn, a preferred group of dior~ano fumarates i9 the dihydrocarbon fumarates of the above formula wherein the value of a is zero. It has been found that for compositions of this invention wherein the organosilicon component (A) is a linear methylsiloxane the dihydrocarbon fumarates provide a superior inhibiting action than the dihydrocarbonoxyalkyl fumarates of the above formula where a has a value of 1.
Unexpectedly, I have found that diallyl fumarate provides faster initial cure, and less drift in cure rate as the composition ages at room temperature, than diallyl maleate and other maleates and fumarates, when the organo-polysiloxane polymer~ Component (A), bears 5-hexenyl radicals as the olefinic hydrocarbon radicals. It is these compositions which have cure rates which approach closely the maximum cure rates that are available in uninhibited higher alkenyl-substituted coating compositions.
Also ~nexpected was the discovery that diethyl fumarate provides faster cure than diethyl maleate, and other maleates and fumarates, when the organopolysiloxane polymer, -18- 1 3 ~ B ~ O 8 Component (A), bears vinyl radical~ as the olefinic hydrocarbon radical~.
Diorgano fumarates can be prepared by any known method. For example, symmetrical diorgano fumarates can be prepared by the full esterification of fumaric acid or fumaryl chloride with ~ suitable alcohol, such as methanol, ethanol, isopropanol, allyl alcohol, methoxyethanol, allyloxyethanol or methoxyisopropanol. Asymmetrical diorgano fumarates can be prepared, for example, by the half esterification of fumaric acid, using a first alcohol, such as methanol, followed by full esterification of the resulting half acid ester with a second alcohol, such as ethanol.
The amount of diorgano fumarate to be used in the compositions of this invention is not critical and can be any amount that will retard the above-described platinum-catalyzed hydrosilylation reaction at room temperature while not preventing said reaction at moderately elevated temperature. While not wishing to be limited by any theory, I believe that there should be at least three molecules of fumarate inhibitor for each platinum 8tom in the compo9ition, to form a room temperature stable complex therebetween.
Preferably a large excess of fumarate molecule9, compared to platinum atom~, is u8ed.
In the liquid organopolysiloxane compositions that are used in the coating method of this invention, the amount of diorgano fumarate is typically sufficient to provide from 25 to 50 molecules thereof for every platinum atom in the composition.
The addition of the Component (D) to a composition comprising (A), (B) and (C) delays cure of the composition at room temperature over long periods of time, but at temperatures in excess of 70C. the inhibiting effect of the diorgano fumarate observed at room temperature disappears and -19- ~3~8508 a faster curing rate is realized. The cure of the curable composition can be retarded at room temperature for short period~ of time or fo~ very lon~ periods of tim~ by the use of a proper amount of dior~ano fumarate. No exact amount of diorgano fumarate can be su~ested to ~ive a specified storage life at room temperature. The rate of cure will depend upon the ratio of diorgano fumarate molecules to platinum atoms in the catalyst, ~he form of the platinum catalyst, the structure of the diorgano fumarate, the structures and amounts of Components (A) and (B) and the presence or absence of other nonessential ingredients.
Diorgano fumarates added in small amounts such as 0.1 weight percent based on the weight of the curable composition provide increased pot life in a~l systems, but, in most cases, do not fully retard the reaction at room temperature.
In larger amounts such as 3 weight percent diorgano fumarate, they provide completely inhibited cures at room temperature.
The amount of diorgano fumarate is therefore dependent upon the desired use, and the nature of the system.
Thus, while I have generally taught the broad and narrow limits for the inhibitor component concentration in my compositions the skilled worker can readily determine the optimum level thereof for each system, if desired.
The composition of this invention can contain any of the optional components commonly used in platinum-catalyzed organosilicon compositions, such as fillers, solvents, surfactants, colorants, stabilizers and physical property modifiers.
Examples of fillers useful in the compositions of this invention include reinforcing fillers and extending filler~. Examples of reinforcing fillers include: silica, such as fume silica and precipitated silica; and treated silica, such as fume or precipitated silica that has been -20- ~308508 reacted with e.g., an organohalosilane, a disiloxane, or a disilazane.
Examples of extending fillers include crushed quartz, aluminum oxide, aluminum silicate, zirconium silicate, magnesium oxide, zinc oxide, talc, diatomaceous earth, iron oxide, calcium carbonate, clay, titania, zirconia, mica, gla99, such as ground glass or glass fiber, ~and, carbon black, graphite, barium sulfate, zinc sulfate, wood flour, cork, fluorocarbon polymer powder, rice hulls, ground peanut shell~, and the like.
Examples of ~aid solvents include aliphatic hydrocarbons, such a~ pentane, hexane, heptane, octane, nonane and the like; aromatic hydrocarbons such as benzene, toluene and xylene; alcohols such as methanol, ethanol, and butanol; ketones such a~ acetone, methylethyl ketone and methylisobutyl ketone; and halogenated solvents such as fluorine-, chlorine-, and bromine-substituted aliphatic or aromatic hydrocarbons, such as trichloroethane, perchloro-ethylene, bromobenzene and the like. Two or more solvents may be used together.
Examples of stabilizers include antimicrobial preparations, mildewcides, antioxidants, flame retardants and ultra-violet radiation stabilizers.
Examples of physical property modifiers include adhesion promoters, crosslinking agents and controlled release additives, such as the siloxane resins disclosed in U.S. Patent No. 3,527,659.
The compositions of this invention can be made by homogeneously mixing Components (A), (B), (C) and (D), and any optional components, using suitable mixing means, such as a spatula, a drum roller, a mechanical stirrer, a three-roll mill, a sigma blade mixer, a bread dough mixer, and a two-roll mill.
-21- 1 3 0 8 ~ 0 a The order of mixing Components (A) through (D) i~
not critical; however, it is preferred that Components (B) and (c) be brought together in the presence of Component (D), most preferably in a final mixing step. Thus, it i5 possible to mix all components in one mixing step immediately prior to the intended use of the curable composition. Alternatively, certain components can be premixed to form two or more package3 which can be stored, i desired, and then mixed in a final step immediately prior to the intended use thereof.
It is preferred to mix Components (C~, tD) and a portion of Component (A), along with certain optional components such as fillers and solvents, to provide a first package and Component (B), along with the remainin~ portion of Component (A), if any, to provide a second package. These two packages can then be stored until the composition of this invention is desired and then homogeneously mixed.
It is also possible to place Components (B), (C) and (D) in three separate packages and to place Component (A) in one or mare of said separate packages and the three packages stored until needed.
The compositions of this invention have utility as formable compositions to provide organosilicon articles such as 0-rings, tubing, wire-coating and gaskets; as encapsulant and sealant compositions; and as coating compositions, among others.
In another aspect, the present invention relates to a process for rendering a solid surface of a substrate less adherent to materials that normally adhere thereto, said process comprising (I) applying to said solid surface a coating of a liquid curable composition comprising an organopolysiloxane component (A) having the formula XMe2SiO(Me2SiO)b(MeXSiO)dSiMe2X, wherein Me denotes methyl, X
denotes a monovalent radical selected from the group -22- ~ 3~8 ~ 8 consisting of olefinic hydrocarbon radicals having from 2 to 12 carbon atoms and R radicals, an average of at least two X
radicals per molecule o~ Component (A) being olefinic hydrocarbon radicals, R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation having from 1 to 20 carbon atoms, b and d have average values of zero or more, and the sum of b plus d has a value sufficient to provide a viscosity at 25C. of at least 25 millipascal-seconds for the Component (A); an organohydrogenpolysiloxane component (B) bearing at least two silicon-bonded hydrogen atoms per molecule thereof and having the average unit formula Re H~SiO(4 e f)/2 wherein R3 denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation, f has a value of from greater than O to 1 and the sum of e plus f has a value of from 1 to 2; an amount of a platinum-containing catalyst component (C~ sufficient to accelerate a reaction of said silicon-bonded olefinic hydrocarbon radicals with said silicon-bonded hydrogen atoms at room temperature; and an amount of an inhibitor component (D) having the formula RlO(DO)aC H
C=C
H ICI(OD)aOR
wherein Rl denotes a monovalent hydrocarbon radical having from 1 to 6 carbon ato~s, each D denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of O or l; the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/2 to 1.5/1, and (II) heating the applied coating for a period of time sufficient to cure the applied coating.
The several components, necessary and optisnal, of the composition~ that are used in the method of this invention are the same a9 the components detailed above for the composition~ of this invention.
In the process of thi~ invention, the liquid curable organopolysiloxane composition is coated onto a solid surface of a substrate, preferably at room temperature, and thereafter heated to effect a cure of the coating. The coating process can be accomplished by any suitable manner known in the art, such as by spreading, brushing, extruding, spraying and rolling.
A significant characteristic of the liquid curable compositions of this invention is the long pot life that they have, wherein the viscosity thereof does not double in value over a period of several hours, thereby allowing an extended application period.
The solid surfaces that can be coated by the process of this invention include cellulosic surfaces such as wood, cardboard and cotton; metallic surfaces such as aluminum, copper, steel and silver; siliceous surfaces such as glass and stone; synthetic polymer surfaces such as polyolefins, polyamides, polyesters and polyacrylates; and others.
As to form, the substrate can be sheetlike, ~uch as an adhesive release liner, a textile or a foil; or substantially three-dimensional in form. The surface of the substrate can be substantially smooth or rough in a regular or irregular manner.
After the liquid curable composition has been coated onto a substrate it is preferably heated moderately to convert the liquid coating to the nonliquid state. By moderately, it is meant to a temperature of from about 70 to 100C.
A significant characteristic o~ the process of this in~ention is the rapid curing that occurs when the coated composition i~ heated to, for example, 70c. Typically, the coated composition will cure fully when heated, for ~xample, at 82c. for 90 seconds or less. Higher temperatures, such as up to 160c., will provide correspondingly shorter curing times.
In a preferred embodiment of the process of this invention, a flexible sheet material, such as paper, metal foil or tape~toc~, is coated with a thin coating of the liquid curable composi tion, preferably in a continuous manner, and the thus-coated material is then heated to rapidly cur~ the coating, to provide a sheetlike material bearing on at least one surface thereof an adhesive-releasing coating.
The adhesive-releasing coating can be subsequently brought into contact with a pressure sensitive adhesive composition, either immediately or at a later time, to form an article having a peelable adhesive/coating interface.
Examples of such an article include, adhe~ive labels having a peelable backing, adhesive tape in roll form and sticky materials packaged in a peelable container, such as food9, asphalt and gum.
The following examples are disclosed to further teach, but not limit, the invention which i5 properly delineated by the appended claims. All amounts (parts and percentages) are by weight unless otherwise indicated.
Viscosities were measured with a rotating spindle viscom~ter.
Bath life of a composition means the time interval required for the viscosity of the composition to reach a -25- ~L3~508 Yalue of twice the room temperature viscosity of the freshly prepared composition.
Cure ti~e for a compo~ition means the time interval required for the composition, when coated onto S2S kraft paper, at a thickne8s of 1 pound per ream, to attain the no smear, no migration, no rub-off condition.
The no ~mear condition was determined by lightly streaking the coating with a finger and observing for the absence of haze in the streaked area.
The no migration condition was determined by firmly adhering a common, pressure sensitive adhesive tape to the coating, removing the tape and folding the removed tspe together, adhesive surfaces to each other. Absence of migration of the coating to the tape was indicated by noting that the toubled tape was as difficult to separate as unused tape Q o doubled.
The no rub-off condition was determined by vigorously rubbing the coating with the index finger and noting that the coating could not be removed from the psper.
The maleates and fumarates disclosed herein were prepared by the reaction of maleic and fumaric acid, respectively, with the appropriate alcohol. A water-azeotroping solvent and concentratet H2S04 were also used to conduct the esterification reaction. Following removal of water of esterification by azeotropic distillation the reaction mixtures were washed with 10% aqueous NaHC~ and then with water, dried and the reaction products were isolated by vacuum fractional distillation.
A 5-hexenyldimethylsiloxane-endblocked copolymer of dimethylsiloxane units and 5-hexenylmethylsiloxane units having the average formula Hex~le2sio(Me2sio)lsl(MeHexsio) ., 26 ~.308508 where Me denotes methyl and Hex denotes CH2=CHCH2CH2CH2CH2-, was prepared according to U.S. Patent No. 4,609,574 by mixing cyclopolydimethylsiloxanes, hydrolyzate o~ 5-hexenylmethyldi-chlorosilane, 5-hexenyl-endblocked polydimethylsiloxane fluid, ~nd KOH in a ~lask and heating to 150C for 5 hours.
After cooling, the mixture was treated with carbon dioxide for 30 minutes to neutralize the KOH. Fuller's Earth (5 g) was added and after 24 hours, the mixture was filtered to yield the copolymer.
U.S. Patent No. 4,609,574 discloses the details of how to prepare the copolymer delineated immediately above, and other 5-hexenyl-substituted silicon compounds such as 5-hexenylmethyldichlorosilane and 5-hexenyldimethylchloro-silane and other polymers, such as 5-hexenyl-endblocked polydimethylsiloxane fluid and the hydrolyzate of 5-hexenylmethyldichlorosilane.
Examples 1 to 10 Each of ten paper coating composition of this invention (Compositions 1 to 10) was prepared by mixing lOg of the 5-hexenyl-endblocked copolymer of dimethylsiloxane units and 5-hexenylmethylsiloxane units, noted above, O.l9g of a platinum catalyst (a soluble platinum complex containing 0.67% platinum formed from chloroplatinic acid and divinyl-tetramethyldisiloxane), a diorgano fumarate cure control additive (See Table I-Inhibitor), and 0.37g of a methyl-hydrogenpolysiloxane crosslinker (a mixture containing 60% of trimethylsiloxane-endblocked polymethylhydrogensiloxane with an average of about 35 siloxane units per polymer molecule and 40% of trimethyl-endblocked copolymer with an average of 3 dimethylsiloxane units and 5 methylhydrogensiloxane units per copolymer molecule).
-27- ~3085~8 For comparison, eight paper coating compositions (Compo~itions a to h) were identically prepared except containing the corresponding maleates instead of fumarate~.
The bath li~e (at 25 or 40C.) and cure time (at 180F=82.2C.) of each of the example coatings and comparison coatings were determined by the procedures noted above and the results are summarized in Table I. These examples illustrate the utility of the compositions of this invention as easily curable coating compositions which have useful bath lives. These examples, when considered with the disclosed comparison examples, also show the improved cure characteristics of the compositions of this invention, with respect to cure time and maintenance of cure time as the composition ages at room temperature and the vi9c09ity increa~es, when the fumarate cure control additive is a diethyl or diallyl fumarate.
: ~`
-28- ~ 3 O 8 5 O 8 TABLE I
COMPOSITIONS CONTAINING HEXENYL POLYMER
COMP. INHIBITOR BATH-LIFE,HR. CURE-TIME.SEC.
IDENT* PPT 25C 40CINITIAL 2XVISCOSITY
1. DAF 5 0. 5 25 50 2. " 10 94.5 - 20 3. " 15 95 40 4. " 20 - 119 40 80 a. DAM 5 23 45 lZO
b. " 10 100-166 60 5. DEF 20 Z 15 6. " " 24 - 20 65 c. DEM 20 44 30 180 7. MEF 4 1 40 8. " 10 0.6 90 120 d. MEM 4 3.25 45 e. " 5 2.7 60 105 f. " " - 30 9. MIF 10 0.3 45 10~ " 20 0.8 180 240 g. MIM 10 72 5 40 40 h. " " 1-23 90 * DAF = Diallyl fumarate. DAM = Diallyl maleate.
DEF = Diethyl fumarate. DEM = Diethyl maleate.
MEF = Methoxyethyl fumarate. MEM = Methoxyethyl maleate.
MIF = Methoxyisopropyl fumarate.
MIM = Metho~yisopropyl maleate.
PPT = Parts per thousand parts of hexenyl-substituted polymer.
Examples 11 to 19 Nine paper coating composition of this invention (Compositions 11 to 19) were prepared by mixing lOg of a vinyl-endblocked copolymer of dimethylsiloxane units and vinylmethylsiloxane units having the average formula ViMe2SiO(Me2SiO)151(MeViSiO)3SiMe2Vi where Me denotes methyl -29- ~308~i08 and Yi denotes CHz=CH- tprepared by mixing cyclopolydimethyl-~iloxanes, cyclopolymethylvinylsiloxanes, vinyl-endblocked polydimethyl~iloxane fluid, and KOH in a flask and heating as wa~ done for the hexenyl-substituted polymer noted above), O.19g of the platinum catalyst of Examples 1 to 10, a diorgano fumarate cure control additive (See Table II-Inhibitor), and 0.37g of the methylhydrogenpolysiloxane crosslinker of ~xamples 1 to 10.
For comparison, six paper coating compositions (Compositions i to n) were identically prepared, except containing the corresponding maleates instead of fumarates.
The bath life (at 25 or 40C.) and cure time (at 180F.=82.2C.) of each of the example coatings and comparison coatings were determined by the procedures noted above and the results are summarized in Table II. These examples illustrate the utility of the compositions of this invention as easily curable coating compositions which have useful bath lives. These examples, when considered with the disclosed comparison examples, also show the improved cure characteristics of the compositions of this invention, with respect to cure time and maintenance of cure time as the composition ages at room temperature and the viscosity increases, when the fumarate cure control additive is a diethyl fumsrate.
~30- ~30~5~8 TABLE II
COMPOSITIONS CONTAINING VINYL POLYMER
C9MP. INHIBITOR BATH-LIFE~HR.CURE-TIME.SEC.
IDENT* PPT 25C 40CINITIAL 2XVISCOSITY
FUMARATE CURE-CONTROL ADDITIVE AND USE THEREOF
The pre~ent invention relate.q ~ener~lly to heat-curable, sili~on-containing compositiGns. More specifically, this invention relates to compositions which cure by way of a platinum-catalyzed reaction of silicon-bonded olefinic hydrocarbon radicals with ~ilicon-bonded hydrogen atoms, wherein the room temperature catalytic activity of the platinum-containing catalyst has been inhibited by the presence of an inhibitor component who3e inhibiting action can be overcome by heating.
Organos,ilicon compositions in which a platinum-containin~ catalyst is inhibited in its cure-promoting activity at room temperature by the presence of a catalyst inhibitor are well known in the organosilicon art. Examples of compositions having platinum catalyst inhibitors include those containing unsaturated organic compounds; such as ethylenically or aromatically unsaturated amides, U.S. Patent No. 4,337,332; acetylenic compounds, U.S. Patent No. 3,445,420; ethylenically unsaturated isocyanates, U.S.
Patent No. 3,882,083; olefinic siloxanes, U.S. Patent No.
3,989,667; and con~ugated ene-ynes, V.S. Patent Nos. 4,465,818 and 4,472,563; other organic compounds such as hydroperoxides, sulfoxides, amines, phosphines, phosphites and nitrile~; and various metal salts.
More relevantly, the unsaturated hydrocarbon diester inhibitors of U.S. Patent No. 4,Z56,870, such as diallyl or diethyl maleate, and the bis-hydrocarbonoxyalkyl maleate inhibitors of U.S. Patent No. 4,562,096, such as bis-(2-methoxyisopropyl) maleate, have been found to be effective for delaying or preventing the room temperature cure of organosilicon compositions which cure by way of a ~308S08 platinum group metal catalyzed reaction. However, the cure time and/or the cure temperature of these maleate-inhibited compositions are/is undesirably increased by the use of these inhibitors.
This problem of increased cure time and/or cure temperature in an inhibited platinum-catalyzed system is of particular significance for applications where the organo-silicon composition is used to rapidly coat a substrate, such as i8 practiced in the adhesive release coating art.
In the coating arts, such as the paper coating art, the coating composition that iq used to coat a substrate should not cure to the extent that its viscosity has increased substantially before it has been applied to the substrate; however, it should rapidly cure thereafter, preferably with only a moderate amount of added energy. This means that the coating compositions preferably should not experience a doubling of its viscosity at ambient temperature for as long as eight hours, but should cure rapidly, at moderately increased temperature, to such an extent that the coated substrate can be further processed.
Furthermore, when the cured coating composition is to be immediately coated with a reactive adhesive, such as an acrylic-based pressure-sensitive adhesive composition, the release coating must be fully cured before the adhesive composition is applied in order to minimize the bonding of the adhesive to the partially cured silicone coating, a phenomenon known as "acrylic weld".
Compositions having improved curing characteristics, and little or no acrylic weld, have been disclosed in U.S. Patent No. 4,609,574. The improvements of these compo9itions have been realized by the use of higher alkenyl radicals, such as hexenyl, instead of the usual vinyl radical, as the reactive olefinic hydrocarbon radical.
1~0850~3 However, even in these improved compositions, the cure rate of the higher al~enyl reaction site has no~ been fully utilized becau3e the catalyst inhibitor is excessively active at elevated temperatures.
The que~t f~r the ideal pl~tinum catalyst inhibitor in silicon-containing compositions, particularly coating composition~, continue~.
It is an ob~ect of this invention to provide improved ~urable organosilicon compositions. It is also an object of this invention to provide organopolysiloxane compositions which do not cure at room temperature for long periods of time but which cure rapidly when heated to moderately elevated temperatures. It is a particular object of the present invention to provide liquid organopolysiloxane coating compositions which remain liquid for hours at temperatures up to 104~F. (40C.) but which cure within 90 second~ when coated onto a substrate and heated to a temperature of as low as 180F. (82C.). It is an additional ob~ect of this invention to provide curable compositions for adhesive release which do not experience acrylic weld.
These objectc, and others which will occur ~o one of ortinary ~kill in the curable organosilicon composition art upon considering the following disclosure and appended claims, are obtained by the present invention which, briefly stated, comprises a curable organosilicon composition comprising a component having silicon-bonded hydrogen atoms, a component having silicon-bonded olefinic hydrocarbon radicals reactive therewith, a platinum-containing catalyst and an effective amount of a diorgano fumarate cure-control, i.e. catalyst inhibitor, component.
Surprisingly, the room temperature cure times of the organopolysiloxane coating compositions of this invention are adequately long, and their cure times at elevated -4- 130~508 ~emperature are advantageously brief, that they are useful in fast-paced coating operations, su~h as adhesive release coating operations wherein the cured coating is further coated in-line, i.e., immediately after being cured, with an acrylic-based adhesive.
The present invention relates to a curable composition comprising (A) an organosilicon compound having an average of from one to three ~ilicon-bonded monovalent radicals per silicon atom selected from tha group consisting of hydrocarbon and halohydrocarbon radicals, there being an average of at least two of said monovalent radicals, per molecule of Component (A), selected from the group consisting of olefinic hydrocarbon radicals, the remaining silicon valences thereof being satisfied by divalent radicals free of aliphatic unsaturation selected from the group consisting of oxygen atoms, hydrocarbon radicals, hydrocarbon ether radicals, halohydrocarbon ether radicals and halohydrocarbon radicals, said divalent radicals linking silicon atoms, (B) an organohydrogensilicon compound containing at least two silicon-bonded hydrogen atoms per molecule thereof and an average of from one to two silicon-bonded monovalent radicals free of aliphatic unsaturation, per silicon atom, selected from the group consisting of hydrocarbon and halohydrocarbon radicals, the remaining silicon valences thereof being satisfied by divalent radicals free of aliphatic unsaturation selected from the group consisting of oxygen atoms, hydrocarbon radicals, hydrocarbon ether radicals, halo-hydrocarbon ether radicals and halohydrocarbon radicals, said divalent radicals linking silicon atoms, (C) an amount of a platinum-containing catalyst sufficient to accelerate a reaction of said silicon-bonded olefinic hydrocarbon radicals with said ~ilicon-bonded hydrogen atoms at room temperature, and (D) an amount of an inhibitor compound for the platinum-containing catalyst sufficient to retard said reaction at room temperature but insufficient to prevent said re ction at elevated temperature, said inhibitor compound ha~ing the formula o RlO(DO)aC H
C=C
H C(OD)aORl wherein each Rl denotes, independently, a monovalent hydro-carbon radical having from 1 to 6 carbon atoms, each D
denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of 0 or 1, the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/100 to 100/1.
Herein the term "curable", as applied to compositions of this invention, generally denotes a chemical change which leads to an increase in the molecular weight of one or more of the components in the composition. Said increase in molecular weight, typically, is accompanied by an increase in the viscosity of the curable composition. For the coating compositions of this invention the term curable denotes a change in the state of the composition from a liquid to a ~olid. For coating compositions of this invention which are to be used as adhesive-release coatings, the term "curable" has a more detailed meaning which encompasses the properties of smear, migration and rub-off of the coating, as delineated below.
The curing of the compositions of this invention is accomplished by hydrosilylation, i.e., a platinum-catalyzed addition reaction between silicon-bonded olefinic hydrocarbon radicals of Component (A) and silicon-bonded hydrogen atoms of Component (B).
~ roadly stated, Component (A) of the compositions of this invention can be any organosilicon compound containing two or more silicon atoms linked by divalent radicals and containing an average of from 1 to 3 silicon-bonded monovalent radicals per silicon, with the proviso that the organosilicon compound contains at least two silicon-bonded olefinic hydrocarbon radicals. This component can be a solid or a liquid, freely flowing or gum-like.
Examples of said divalent radicals linking silicon atoms in Component (A) include oxygen atoms, which provide siloxane bonds, and aliphatically saturated hydrocarbon, hydrocarbon ether, halohydrocarbon ether and halohydrocarbon radicals which provide silcarbane bonds. The divalent radicals can be the same or different, as desired.
Examples of suitable divalent hydrocarbon radicals include any alkylene radical, such as -CH2-, -CH2CH2-, CH (CH )CH- -(CH2)4-, -CH2CH(CH3)CH2 ~ ( 2 6 -(CH2)18-; cycloal~ylene radical, such as cyclohexylene;
arylene ratical, such as phenylene and combinations of hydrocarbon radicals, such as benzylene, i.e. -C6H4CYA2-.
Examples of suitable divalent halohydrocarbon radicals include any divalent hydrocarbon radical wherein one or more hydrogen atoms have been replaced by halogen, such as fluorine, chlorine or bromine. Preferable divalent halo-hydrocarbon radicals have the formula -CH2CH2CnF2nCH2CH2-wherein n has a value of from 1 to 10 such as, for example,ru ru r~ r~ ru ru - v~l2V~l2vr 2v~ 2V' 2 2 Examples of suitable divalent hydrocarbon ether radicals and halohydrocarbon ether radicals include -7- 1308~08 -cH CH2CH2CH2-' ~CH2CH2CF2CF2C~2CH2 ' 2 2 2 2 2 2 and -c6~4-o-C6H4-Examples of said monovalent radicals in Component(A) include halohydrocarbon radicals free of aliphatic unsaturation and hydrocarbon radicals.
Examples of suitable monovalent hydrocarbon radicals include alkyl radicals, such as CH3-, CH3CH2-, 3~2 ' 8H17 ~ ClOH21- and C20H4l-; cycloaliphatic radicals, such as cyclohexyl; aryl radicals, such as phenyl, tolyl, xylyl, anthracyl and xenyl; aralkyl radicals, such as benzyl and 2-phenylethyl; and olefinic hydrocarbon radicals, such as vinyl, allyl, methallyl, 3-butenyl, 5-hexenyl, 7-octenyl, cyclohexenyl and styryl. Alkenyl radicals are preferably terminally unsaturated. Of the higher alkenyl radicals, those selected from the group consisting of 5-hexenyl, 7-octenyl, and 9-decenyl are preferred because of the more ready availability of the alpha,omega-dienes used to prepare the alkenylsiloxanes. Highly preferred monovalent hydrocarbon radical for the silicon-containing components of the compositions of this invention are methyl, phenyl, vinyl and 5-hexenyl.
Examples of suitable aliphatically saturated monovalent halohydrocarbon radicals include any monovalent hydrocarbon radical which is free of aliphatic unsaturation and has at least one of its hydrogen atoms replaced with halogen, such as fluorine, chlorine or bromine. Preferable monovalent halohydrocarbon radicals have the formula CnF2n+lCH2CH2- wherein n has a value of from 1 to 10, such as, for example, CF3CH2CH2 and C4F9CH2CH2 .
Component (A) of the compositions of this invention is typically an organopolysiloxane having the average unit formula Rc ~iO(4_C)/2 wherein R2 denotes said monovalent radicals, delineated and limited above, and c has a value of from 1 to 3, such as 1.2, 1.9, 2.0, 2.1, 2.4 and 3Ø
Suitable siloxane units in the organopolysiloxanes having the above average unit formula have the formulae R32SiO1~2, R2 SiO2/2, R SiO3/2 and SiO4/2. Said siloxane units can be combined in any molecular arrangement such as linear, branched, cyclic and combinations thereof, to provide organo-polysiloxanes that are useful as component (A).
A preferred organopolysiloxane Component (A) for the composition of this invention is a substantially linear organopolysiloxane having the formula XR2SiO(XRSiO)XSiR2X.
By substantially linear, it is meant that the component contains no more than trace amounts of silicon atoms bearin~
3 or 4 siloxane linkaees. It is to be understood that the term sub~tantially linear encompasses organopolysiloxanes which can contain up to about 15 percent by weight cyclo-polysiloxanes which are frequently co-produced with the linear or~anopolysiloxanes.
In the formula shown immediately above, each R
denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic un~aturation and having from l to 20 carbon atoms, as exemplified above. The ~everal R radicals can be identical or different, as desired. Additionally, each X
denotes an R radical or an olefinic hydrocarbon radical having from 2 to 12 carbon atoms, as exemplified above. Of course, at least two X radicals are olefinic hydrocarbon radicals.
The value of the subscript x in the above formula i9 such that the linear organopolysiloxane (A) has a viscosity at 25~C. of at least 25 millipascal-seconds (25 centipoise). The exact value of x that is needed to provide a viscosity value falling within said limit depends upon the identity of the X and R radicals; however, for hydrocarbyl-~9~ 130~508 terminated polydimethylsiloxane x will have a value of atleast about 25.
In terms of preferred monovalent hydrocarbon radicals, noted above, example~ of preferred linear organo-polysiloxanes of the above formula which are suitable as Component (A3 for the composition of this invention include PhMeViSiO(Me2SiO)10OSiPhMeVi, HexMe2SiO tMe2SiO ) 150SiMe2Hex 9 YiMe2SiO(Me2SiO)lOO(HeXMeSiO)2SiMe2Vi, ViMe2sio(Me2sio)o 95x(MeViSi)O.05xsiMe2v HexMe2SiO(Me2SiO)lso(HeXMesi)4siMe2 Me3SiO(Me2siO)o gxtMevisio)o.lxSiMe3' Me3SiO(Me2SiO)1OO(MeHexSiO~8SiMe3, (Me2siO)0.93X(Mephsio)o 07xsiphMevi and viMe2si(Me2si)xsiMe2vi wherein Me, Vi, Hex and Ph denote methyl, vinyl, 5-hexenyl and phenyl, respectively.
For the coating composition of this invention, it i8 highly preferred that the linear organopolysiloxanes (A) have the formula XMe2SiO(Me2SiO)b(MeXSiO)dSiMe2X wherein X is as noted above and the sum of b plus d is equal to x, also noted above. The values of the subscripts b and d can each be zero or Breater; however, the val~se of d is typically less than O.lb such as zero, 0.02b or 0.08b. Examples of highly preferred linear organopolysiloxanes (A) for adhesi.ve-release coating compositions of this invention include Me3SiO(Me2SiO)b(MeHexSiO)dSiMe Me3SiO(tle2SiO)b(MeViSiO)dSiMe3 , HexMe2SiO(Me2SiO)b(MeHexSiO)dSiMe2Hex and ViMe2SiO(Me2,SiO)b(MeViSiO)dSiMe2Vi.
In a preferred embodiment of the present invention, wherein the curable composition, preferably solventless, is used to coat a solid substrate, such as paper, with an 130!350~
adhesive-releasing coating, the value of b plus d in the highly preferred organopolysiloxane (A) is sufficient to provide a viscosity at Z5C. for the Component (A) of at least 100 mPa-s, such a~ from about 100 mPa-s to about 100 Pa-s, preferably from about 100 mPa s to 10 Pa- s and, most preferably, from 100 mPa-~ to 5 Pa-s; ~aid viscosities corresponding approximately to values of b + d of at least 60, such as from 6~ to 1000, preferably to 520 and, most preferably, to 420.
Broadly stated, Component (B) of the compositions of this invention can be any organohydrogensilicon compound which is free of aliphatic unsaturation and contains two or more silicon atoms linked by divalent radicals, an average of from one to two silicon-bonded monovalent radicals per silicon atom and an average of at least two, and preferably three or more, silicon-bonted hydrogen atoms per molecule thereof.
Examples of said divalent radicals linking silicon atoms in Component (B) are as delineated above for Component (A), including preferred examples. As with Component (A), the divalent radicals within Component (B) can be identical or different, as desired. Furthermore, the divalent radicals that are present in Component (B) can, but need not, be the same as the divalent radicals that are present in Component (A).
Examples of said monovalent radicals in Component (B) include hydrocarbon and halohydrocarbon radicals, as delineated above for Component (A), including preferred examples, which are free of aliphatic unsaturation. The monovalent radicals that are present in Component (B) can, but need not, be the same ag the monovalent radicals that are present in Component (A).
.308S0~
component (B) must contain an average of at least two silicon-bonded hydrogen atoms per molecule thereof.
Preferably, component (B) contains an average of three or more silicon-bonded hydrogen atoms such as, fos example, 5, 10, 20, 40 and more.
component (~) typically has a 100 percen~ siloxane structure, i.e., an organohydrogenpolysiloxane structure having the average unit formula Re3HfSiO~4 e f)/2 wherein R3 denotes said monovalent radical free of aliphatic unsaturation, f has a value of from ~reater than 0 to 1, such as 0.001, 0.01, 0.1 and 1.0, and the sum of e plus f has a value of from 1 to Z, such as 1.2, 1.9 and ZØ
Suitable siloxane units in ~he organohydrogenpoly-siloxanes having the average unit formula immediately above have the formulae R3 Si0l/2~ R2 ~Sil/2' R2 Si2/2' R HSiO2/2, R SiO3/2, HSiO3/2 and SiO4/2. Said siloxane units can be combined in any molecular arrangement sLlch as linear, branched, cyclic and combinations thereof, to provide organohydrogenpolysiloxanes that are useful aq Component (B).
A preferred organohydrogenpolysiloxane Component (B) for the composition~ of this invention is a substantially linear organohydrogenpolysiloxane having the formula YR2SiO(YRSiO)ySiR2Y wherein each R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation and having Prom 1 to 20 carbon atoms, as exemplified above. The several R radicals can be identical or different, as desired. Additionally, each Y denotes a hydrogen atom or an R radical. Of course, at least two Y
radicals must be hydrogen atoms.
The value of the subscript y is not critical;
however, it is preferably such that the organohydrogenpoly-siloxane Component (B3 has a viscosity at 25C. of up to 100 millipascal-seconds. The exact value of y needed to provide a vi~co~ity value falling within ~aid limits depends upon the number and identity of the R radicals; however, for organo-hydrogenpolysiloxanes containinK only methyl radicals as R
radicals y will have a value of from about O to about 100.
In terms of preferred monovalent hydrocarbon radicals, noted above, examples of linear organohydrogen-polysiloxanes of the above formula which are suitable as Component (B) for the compositions of this invention include HMe2SiO(Me2SiO)ySiMe2H, Me3SiO(MeHSiO)ySiMe3, HMe2SiO(Me2SiO)0 5y(MeHSiO)0 5ySiMe2H, HMe2Si(Me2SiO)0 5y(MePhSiO)0 1y(MeHSiO)0 4 SiMe2H, Me3SiO(Me2SiO)0 4y(MeHSiO)0 6ySiMe3, (MeHSiO)y, (HMe2SiO)4Si and MeSi(OSiMe2H)3.
Highly preferred linear organohydrogenpoly9iloxane ~B) for the coating composition8 of this invention have the for~ula YMe2SiO(Me2SiO)p(MeYSiO)qSiMe2Y wherein Y denotes a hydrogen atom or an R radical, free of aliphatic unsaturation. Again, an average of at least two Y radicals per molecule of Component (B) must be hydrogen atoms. The subscripts p and q can have average values of zero or more and the sum of p plu9 q has a value equal to y, noted above.
For the adhesive-releasing coating compositions of this invention, Y should be H or methyl. A particularly effective organohydrogenpolysiloxane component (B) for the compositions of this invention comprises a mixture of two compounds having the formulae Me3SiO(MeHSiO)35SiMe3 and Me3SiO(Me2SiO)3(MeHSiO)sSiMe3-The amount~ of Components (A) and (B) that are used in the compositions of this invention are not narrowly limited. Said amounts, expressed in terms of the ratio of the number of silicon-bonded hydrogen atoms of Component (B) to the number of silicon-bonded olefinic hydrocarbon radicals of Component (A), as is typically done, are sufiicient to -13- ~30850~
provide a value for said ratio of from 1/lOO to 100/l, usually from l/ZO to 20/1, and preferably from 1/2 to 20/1.
For the liquid ~oating compo~itions of this in~ention which are to be used in the coating method of this invention, hereinbelow delineated, the value of said ratio should have a value of from 1/2 to 1.5/1, and preferably about 1/1.
Organosilicon polymers are, of course, well known in the orga~osilic~n art. Organopolysiloxanes are clearly the most significant and most widely used form of organo-silicon polymers in the art, and in this invention; many are commercially prepared. The preparation of the organosilicon components that are used in the compositions of this invention i~ well documented and needs no intensive delineation herein.
Briefly, organopolysiloxanes are typically prepared by way of hydrolysis and condensation of hydrolyzable silanes such as Me2SiC12, Me3SiCl, MeSiC13, SiC14, Me2Si(OMe)2, MeSi(OMe)3 and Si(OCH2CH3)4 or by way of acid- or alkali-catalyzed siloxane equilibration of suitable siloxane precursors such as (Me2SiO)4 and Me3SiOSiMe3, which themselves are prepared by way of said hydrolysis and condensation reactions.
Organopolysiloxane Component (A) can be prepared as noted above with the proviso that a silane or siloxane containing at least one silicon-bonded olefinic hydrocarbon radical i~ used, alone or in con~unction with other silanes or siloxanes, in sufficient amount to provide the necessary number of olefinic hydrocarbon radicals in the organopoly-siloxane. Examples of olefinic hydrocarbon radical-containing silanes or siloxanes include, but are not limited to, ViMe2SiCl, HexMe2SiCl, MeViSiC12, MeHexSiC12, ViSiC13, HexSiCl3, (MeViSiO)4, HexMe2SiOSiMe2Hex and ViMe2SiOSiMe2Vi.
-14- i308508 It is usually preferred t~ prepare olefini~
siloxanes by hydrolyzing a readily hydrolyzable silane, such as 5-hexenyl- or ~inyl-methyldichlorosilane, in excess water and then equilibrating the resulting hydrolyzate with cyclo-polydimethylsiloxanes and a siloxane oligomer containing triorganosiloxane end groups, using a base cataly~t such as KOH. Howev~r, it is believed that olefinic polydiorgano-siloxanes may also be advantageously prepared in a one-step acid-catalyzed process wherein the hydrolyzable silane is hydrolyzed and simultaneously equilibrated with cyclopolydi-methyl~iloxanes and siloxane oligomer containing end groups.
Alternatively, known polyorganohydrogensiloxanes bearing reactive SiH group~ can be reacted with an alpha,omega-diene, such as 1,5-hexadiene, to prepare higher alkenyl-substituted organopolysiloxanes. It should be noted that linear siloxanes produced by equilibration procedures may contain small amounts such as 0 to 15 weight percent of cyclopolydiorganosiloxanes which may be volatile at temperatures up to 150C. For the purpose9 of this invention either siloxanes that still contain the small amounts of cyclics, or siloxanes from which the co-produced cyclics have been removed by volatilization may be used.
Organohydrogenpolysiloxane Component (B) can be prepared as noted above with the proviso that a silane or siloxane containing at least one silicon-bonded hydrogen atom, instead of olefinic hydrocarbon radical, is used, alone or in combination with other silanes or siloxanes, in sufficient amount to provide the necessary number of silicon-bonded hydrogen atoms in the organohydrogenpoly-siloxane. Example~ of hydrogen atom-containing silanes or siloxanes include, but are not limited to, HMe2SiCl, HMeSiC12, HSiC13, HMe2SiOSiMe2H and (MeHSiO)4. Component (~) -15- ~ 3 0 ~ 5 O 8 is preferably prepared under nonalkaline conditions to minimize hydrolysis of the SiH linkage.
Organosilicon polymers having a mix of silcarbane and siloxsne structure can be prepared, for example, from monomeric 9pecies that have nonoxygen divalent radicals, such as Ol/2Me2SiCH2CH2Me2SiOl/2 or ClMe2sic6H4siMe2cl~ uging standard hydrolysis and condensation reactions, noted above, and incorporating one or more of the olefinic hydrocarbon radicals or hydrogen atom-containing silanes or siloxanes noted above, and other silanes or siloxanes, as desired.
Organosilicon polymers which contain no siloxane bonds can be prepared, for example, by a hydrosilylation reaction between silanes or silcarbanes bearing silicon-bonded olefinically unsaturated hydrocarbon radical~, such a~
Vi2SiMe2 or ViMe2SiC6H4SiMe2Vi and silanes or silcarbanes bearing silicon-bonded hydrogen atoms, such as H2SiMe2 or l~e~2SiC6H4SiMe2H .
Other suitable methods for preparing the organo-silicon components that are used in the composition~ of this invention also occur in the organosilicon art.
Broadly stated, Component (C) of the composition of this invention is a catalyst component which facilitates the reaction of the silicon-bonded hydrogen atom~ of Component (~) with the ~ilicon-bonded olefinic hydrocarbon radicals of Component (A) and can be any platinum-containing catalyst component. For example, Component (C~ can be platinum metal;
a carrier, such as silica gel or powdered charcoal, bearing Flstinum metal; or a compound or complex of a platinum metal.
A typical platinum-containing catalyst component in the organopolysiloxane compositions of this invention is any form of chloroplatinic acid, such as, for example, the readily available hexahydrate form or the anhydrous form, because of its easy dispersibility in organosiloxane system~.
-16- 1 3085~8 A particularly useful form of chloroplatinic acid i8 that composition obtained when it is reacted with an aliphatically unsaturated organosilicon compound such as divinyltetramethyldisiloxane, as disclosed by U.S. Patent No.
3,419,593.
The amount of platinum-containing cataly~t component that is used in the compositions of this invention is not narrowly limited a~ long as there is a sufficient amount to accelerate a room temperature reaction between the silicon-bonded hydrogen atom~ of Component (B) with the silicon-bonded olefinic hydrocarbon radicals of Component (A). The exact nece~sary amount of said catalyst component will depend upon the particular catalyst and i9 not easily predictable. However, for chloroplatinic acid said amount can be as low as one part by weieht of platinum for every one million parts by weight of organosilicon Components (A) plus (B). Preferably, said amount is at least 10 parts by weight, on the same basis.
For compositions of this invention which are to be used in the coating method of this invention the amount of platinum-containing catalyst component to be used is preferably sufficient to provide from 10 to SOO parts by weight platinum per one million parts by weight of organo-polysiloxane Components (A) plus (B).
Broadly stated, Component (D) of the compositions of this invention is any diorgano fumarate having the formula trans-RlO(DO)a(O)CC~=CHC(O)(OD)aORl. The diorgano fumarate can be a dihydrocarbon fumarate or a dihydrocarbonoxyalkyl fumarate. That is to say, the value of subscript a in the formula immediately above can have a value equal to zero or 1. The individual value~ of a can be identical or different, as desired.
-17- 1 3 0 8 ~ ~3 The hydrocarbon radical, i.e., the ~1 radical, in the above formula has from 1 to 6 carbon atoms and can be, for example, an al~yl radical such as methyl, ethyl, propyl, isopropyl ~ butyl, pentyl or hexyl; an aryl radical such as phenyl; an alkenyl radical such as vinyl or allyl; or a cyclohydrocarbon radical such as cyclohe~yl.
In the above formula for the diorgano fumarate each D denotes, independently, an alkylene radical having from 2 to 4 carbon atoms such as -CH2CH2-, -CH2(CH3)CH-, 2 2 H2 ~ CH2CH2CH2cH2-~ -CH2(CH3CH2)CH- and -CH2CH2(CH3)CH-. The indi~idual D radicals can be identical or different, a~ desired.
In terms of ease of preparation and inhibiting effect in the compositions of this inventiGn, a preferred group of dior~ano fumarates i9 the dihydrocarbon fumarates of the above formula wherein the value of a is zero. It has been found that for compositions of this invention wherein the organosilicon component (A) is a linear methylsiloxane the dihydrocarbon fumarates provide a superior inhibiting action than the dihydrocarbonoxyalkyl fumarates of the above formula where a has a value of 1.
Unexpectedly, I have found that diallyl fumarate provides faster initial cure, and less drift in cure rate as the composition ages at room temperature, than diallyl maleate and other maleates and fumarates, when the organo-polysiloxane polymer~ Component (A), bears 5-hexenyl radicals as the olefinic hydrocarbon radicals. It is these compositions which have cure rates which approach closely the maximum cure rates that are available in uninhibited higher alkenyl-substituted coating compositions.
Also ~nexpected was the discovery that diethyl fumarate provides faster cure than diethyl maleate, and other maleates and fumarates, when the organopolysiloxane polymer, -18- 1 3 ~ B ~ O 8 Component (A), bears vinyl radical~ as the olefinic hydrocarbon radical~.
Diorgano fumarates can be prepared by any known method. For example, symmetrical diorgano fumarates can be prepared by the full esterification of fumaric acid or fumaryl chloride with ~ suitable alcohol, such as methanol, ethanol, isopropanol, allyl alcohol, methoxyethanol, allyloxyethanol or methoxyisopropanol. Asymmetrical diorgano fumarates can be prepared, for example, by the half esterification of fumaric acid, using a first alcohol, such as methanol, followed by full esterification of the resulting half acid ester with a second alcohol, such as ethanol.
The amount of diorgano fumarate to be used in the compositions of this invention is not critical and can be any amount that will retard the above-described platinum-catalyzed hydrosilylation reaction at room temperature while not preventing said reaction at moderately elevated temperature. While not wishing to be limited by any theory, I believe that there should be at least three molecules of fumarate inhibitor for each platinum 8tom in the compo9ition, to form a room temperature stable complex therebetween.
Preferably a large excess of fumarate molecule9, compared to platinum atom~, is u8ed.
In the liquid organopolysiloxane compositions that are used in the coating method of this invention, the amount of diorgano fumarate is typically sufficient to provide from 25 to 50 molecules thereof for every platinum atom in the composition.
The addition of the Component (D) to a composition comprising (A), (B) and (C) delays cure of the composition at room temperature over long periods of time, but at temperatures in excess of 70C. the inhibiting effect of the diorgano fumarate observed at room temperature disappears and -19- ~3~8508 a faster curing rate is realized. The cure of the curable composition can be retarded at room temperature for short period~ of time or fo~ very lon~ periods of tim~ by the use of a proper amount of dior~ano fumarate. No exact amount of diorgano fumarate can be su~ested to ~ive a specified storage life at room temperature. The rate of cure will depend upon the ratio of diorgano fumarate molecules to platinum atoms in the catalyst, ~he form of the platinum catalyst, the structure of the diorgano fumarate, the structures and amounts of Components (A) and (B) and the presence or absence of other nonessential ingredients.
Diorgano fumarates added in small amounts such as 0.1 weight percent based on the weight of the curable composition provide increased pot life in a~l systems, but, in most cases, do not fully retard the reaction at room temperature.
In larger amounts such as 3 weight percent diorgano fumarate, they provide completely inhibited cures at room temperature.
The amount of diorgano fumarate is therefore dependent upon the desired use, and the nature of the system.
Thus, while I have generally taught the broad and narrow limits for the inhibitor component concentration in my compositions the skilled worker can readily determine the optimum level thereof for each system, if desired.
The composition of this invention can contain any of the optional components commonly used in platinum-catalyzed organosilicon compositions, such as fillers, solvents, surfactants, colorants, stabilizers and physical property modifiers.
Examples of fillers useful in the compositions of this invention include reinforcing fillers and extending filler~. Examples of reinforcing fillers include: silica, such as fume silica and precipitated silica; and treated silica, such as fume or precipitated silica that has been -20- ~308508 reacted with e.g., an organohalosilane, a disiloxane, or a disilazane.
Examples of extending fillers include crushed quartz, aluminum oxide, aluminum silicate, zirconium silicate, magnesium oxide, zinc oxide, talc, diatomaceous earth, iron oxide, calcium carbonate, clay, titania, zirconia, mica, gla99, such as ground glass or glass fiber, ~and, carbon black, graphite, barium sulfate, zinc sulfate, wood flour, cork, fluorocarbon polymer powder, rice hulls, ground peanut shell~, and the like.
Examples of ~aid solvents include aliphatic hydrocarbons, such a~ pentane, hexane, heptane, octane, nonane and the like; aromatic hydrocarbons such as benzene, toluene and xylene; alcohols such as methanol, ethanol, and butanol; ketones such a~ acetone, methylethyl ketone and methylisobutyl ketone; and halogenated solvents such as fluorine-, chlorine-, and bromine-substituted aliphatic or aromatic hydrocarbons, such as trichloroethane, perchloro-ethylene, bromobenzene and the like. Two or more solvents may be used together.
Examples of stabilizers include antimicrobial preparations, mildewcides, antioxidants, flame retardants and ultra-violet radiation stabilizers.
Examples of physical property modifiers include adhesion promoters, crosslinking agents and controlled release additives, such as the siloxane resins disclosed in U.S. Patent No. 3,527,659.
The compositions of this invention can be made by homogeneously mixing Components (A), (B), (C) and (D), and any optional components, using suitable mixing means, such as a spatula, a drum roller, a mechanical stirrer, a three-roll mill, a sigma blade mixer, a bread dough mixer, and a two-roll mill.
-21- 1 3 0 8 ~ 0 a The order of mixing Components (A) through (D) i~
not critical; however, it is preferred that Components (B) and (c) be brought together in the presence of Component (D), most preferably in a final mixing step. Thus, it i5 possible to mix all components in one mixing step immediately prior to the intended use of the curable composition. Alternatively, certain components can be premixed to form two or more package3 which can be stored, i desired, and then mixed in a final step immediately prior to the intended use thereof.
It is preferred to mix Components (C~, tD) and a portion of Component (A), along with certain optional components such as fillers and solvents, to provide a first package and Component (B), along with the remainin~ portion of Component (A), if any, to provide a second package. These two packages can then be stored until the composition of this invention is desired and then homogeneously mixed.
It is also possible to place Components (B), (C) and (D) in three separate packages and to place Component (A) in one or mare of said separate packages and the three packages stored until needed.
The compositions of this invention have utility as formable compositions to provide organosilicon articles such as 0-rings, tubing, wire-coating and gaskets; as encapsulant and sealant compositions; and as coating compositions, among others.
In another aspect, the present invention relates to a process for rendering a solid surface of a substrate less adherent to materials that normally adhere thereto, said process comprising (I) applying to said solid surface a coating of a liquid curable composition comprising an organopolysiloxane component (A) having the formula XMe2SiO(Me2SiO)b(MeXSiO)dSiMe2X, wherein Me denotes methyl, X
denotes a monovalent radical selected from the group -22- ~ 3~8 ~ 8 consisting of olefinic hydrocarbon radicals having from 2 to 12 carbon atoms and R radicals, an average of at least two X
radicals per molecule o~ Component (A) being olefinic hydrocarbon radicals, R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation having from 1 to 20 carbon atoms, b and d have average values of zero or more, and the sum of b plus d has a value sufficient to provide a viscosity at 25C. of at least 25 millipascal-seconds for the Component (A); an organohydrogenpolysiloxane component (B) bearing at least two silicon-bonded hydrogen atoms per molecule thereof and having the average unit formula Re H~SiO(4 e f)/2 wherein R3 denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation, f has a value of from greater than O to 1 and the sum of e plus f has a value of from 1 to 2; an amount of a platinum-containing catalyst component (C~ sufficient to accelerate a reaction of said silicon-bonded olefinic hydrocarbon radicals with said silicon-bonded hydrogen atoms at room temperature; and an amount of an inhibitor component (D) having the formula RlO(DO)aC H
C=C
H ICI(OD)aOR
wherein Rl denotes a monovalent hydrocarbon radical having from 1 to 6 carbon ato~s, each D denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of O or l; the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/2 to 1.5/1, and (II) heating the applied coating for a period of time sufficient to cure the applied coating.
The several components, necessary and optisnal, of the composition~ that are used in the method of this invention are the same a9 the components detailed above for the composition~ of this invention.
In the process of thi~ invention, the liquid curable organopolysiloxane composition is coated onto a solid surface of a substrate, preferably at room temperature, and thereafter heated to effect a cure of the coating. The coating process can be accomplished by any suitable manner known in the art, such as by spreading, brushing, extruding, spraying and rolling.
A significant characteristic of the liquid curable compositions of this invention is the long pot life that they have, wherein the viscosity thereof does not double in value over a period of several hours, thereby allowing an extended application period.
The solid surfaces that can be coated by the process of this invention include cellulosic surfaces such as wood, cardboard and cotton; metallic surfaces such as aluminum, copper, steel and silver; siliceous surfaces such as glass and stone; synthetic polymer surfaces such as polyolefins, polyamides, polyesters and polyacrylates; and others.
As to form, the substrate can be sheetlike, ~uch as an adhesive release liner, a textile or a foil; or substantially three-dimensional in form. The surface of the substrate can be substantially smooth or rough in a regular or irregular manner.
After the liquid curable composition has been coated onto a substrate it is preferably heated moderately to convert the liquid coating to the nonliquid state. By moderately, it is meant to a temperature of from about 70 to 100C.
A significant characteristic o~ the process of this in~ention is the rapid curing that occurs when the coated composition i~ heated to, for example, 70c. Typically, the coated composition will cure fully when heated, for ~xample, at 82c. for 90 seconds or less. Higher temperatures, such as up to 160c., will provide correspondingly shorter curing times.
In a preferred embodiment of the process of this invention, a flexible sheet material, such as paper, metal foil or tape~toc~, is coated with a thin coating of the liquid curable composi tion, preferably in a continuous manner, and the thus-coated material is then heated to rapidly cur~ the coating, to provide a sheetlike material bearing on at least one surface thereof an adhesive-releasing coating.
The adhesive-releasing coating can be subsequently brought into contact with a pressure sensitive adhesive composition, either immediately or at a later time, to form an article having a peelable adhesive/coating interface.
Examples of such an article include, adhe~ive labels having a peelable backing, adhesive tape in roll form and sticky materials packaged in a peelable container, such as food9, asphalt and gum.
The following examples are disclosed to further teach, but not limit, the invention which i5 properly delineated by the appended claims. All amounts (parts and percentages) are by weight unless otherwise indicated.
Viscosities were measured with a rotating spindle viscom~ter.
Bath life of a composition means the time interval required for the viscosity of the composition to reach a -25- ~L3~508 Yalue of twice the room temperature viscosity of the freshly prepared composition.
Cure ti~e for a compo~ition means the time interval required for the composition, when coated onto S2S kraft paper, at a thickne8s of 1 pound per ream, to attain the no smear, no migration, no rub-off condition.
The no ~mear condition was determined by lightly streaking the coating with a finger and observing for the absence of haze in the streaked area.
The no migration condition was determined by firmly adhering a common, pressure sensitive adhesive tape to the coating, removing the tape and folding the removed tspe together, adhesive surfaces to each other. Absence of migration of the coating to the tape was indicated by noting that the toubled tape was as difficult to separate as unused tape Q o doubled.
The no rub-off condition was determined by vigorously rubbing the coating with the index finger and noting that the coating could not be removed from the psper.
The maleates and fumarates disclosed herein were prepared by the reaction of maleic and fumaric acid, respectively, with the appropriate alcohol. A water-azeotroping solvent and concentratet H2S04 were also used to conduct the esterification reaction. Following removal of water of esterification by azeotropic distillation the reaction mixtures were washed with 10% aqueous NaHC~ and then with water, dried and the reaction products were isolated by vacuum fractional distillation.
A 5-hexenyldimethylsiloxane-endblocked copolymer of dimethylsiloxane units and 5-hexenylmethylsiloxane units having the average formula Hex~le2sio(Me2sio)lsl(MeHexsio) ., 26 ~.308508 where Me denotes methyl and Hex denotes CH2=CHCH2CH2CH2CH2-, was prepared according to U.S. Patent No. 4,609,574 by mixing cyclopolydimethylsiloxanes, hydrolyzate o~ 5-hexenylmethyldi-chlorosilane, 5-hexenyl-endblocked polydimethylsiloxane fluid, ~nd KOH in a ~lask and heating to 150C for 5 hours.
After cooling, the mixture was treated with carbon dioxide for 30 minutes to neutralize the KOH. Fuller's Earth (5 g) was added and after 24 hours, the mixture was filtered to yield the copolymer.
U.S. Patent No. 4,609,574 discloses the details of how to prepare the copolymer delineated immediately above, and other 5-hexenyl-substituted silicon compounds such as 5-hexenylmethyldichlorosilane and 5-hexenyldimethylchloro-silane and other polymers, such as 5-hexenyl-endblocked polydimethylsiloxane fluid and the hydrolyzate of 5-hexenylmethyldichlorosilane.
Examples 1 to 10 Each of ten paper coating composition of this invention (Compositions 1 to 10) was prepared by mixing lOg of the 5-hexenyl-endblocked copolymer of dimethylsiloxane units and 5-hexenylmethylsiloxane units, noted above, O.l9g of a platinum catalyst (a soluble platinum complex containing 0.67% platinum formed from chloroplatinic acid and divinyl-tetramethyldisiloxane), a diorgano fumarate cure control additive (See Table I-Inhibitor), and 0.37g of a methyl-hydrogenpolysiloxane crosslinker (a mixture containing 60% of trimethylsiloxane-endblocked polymethylhydrogensiloxane with an average of about 35 siloxane units per polymer molecule and 40% of trimethyl-endblocked copolymer with an average of 3 dimethylsiloxane units and 5 methylhydrogensiloxane units per copolymer molecule).
-27- ~3085~8 For comparison, eight paper coating compositions (Compo~itions a to h) were identically prepared except containing the corresponding maleates instead of fumarate~.
The bath li~e (at 25 or 40C.) and cure time (at 180F=82.2C.) of each of the example coatings and comparison coatings were determined by the procedures noted above and the results are summarized in Table I. These examples illustrate the utility of the compositions of this invention as easily curable coating compositions which have useful bath lives. These examples, when considered with the disclosed comparison examples, also show the improved cure characteristics of the compositions of this invention, with respect to cure time and maintenance of cure time as the composition ages at room temperature and the vi9c09ity increa~es, when the fumarate cure control additive is a diethyl or diallyl fumarate.
: ~`
-28- ~ 3 O 8 5 O 8 TABLE I
COMPOSITIONS CONTAINING HEXENYL POLYMER
COMP. INHIBITOR BATH-LIFE,HR. CURE-TIME.SEC.
IDENT* PPT 25C 40CINITIAL 2XVISCOSITY
1. DAF 5 0. 5 25 50 2. " 10 94.5 - 20 3. " 15 95 40 4. " 20 - 119 40 80 a. DAM 5 23 45 lZO
b. " 10 100-166 60 5. DEF 20 Z 15 6. " " 24 - 20 65 c. DEM 20 44 30 180 7. MEF 4 1 40 8. " 10 0.6 90 120 d. MEM 4 3.25 45 e. " 5 2.7 60 105 f. " " - 30 9. MIF 10 0.3 45 10~ " 20 0.8 180 240 g. MIM 10 72 5 40 40 h. " " 1-23 90 * DAF = Diallyl fumarate. DAM = Diallyl maleate.
DEF = Diethyl fumarate. DEM = Diethyl maleate.
MEF = Methoxyethyl fumarate. MEM = Methoxyethyl maleate.
MIF = Methoxyisopropyl fumarate.
MIM = Metho~yisopropyl maleate.
PPT = Parts per thousand parts of hexenyl-substituted polymer.
Examples 11 to 19 Nine paper coating composition of this invention (Compositions 11 to 19) were prepared by mixing lOg of a vinyl-endblocked copolymer of dimethylsiloxane units and vinylmethylsiloxane units having the average formula ViMe2SiO(Me2SiO)151(MeViSiO)3SiMe2Vi where Me denotes methyl -29- ~308~i08 and Yi denotes CHz=CH- tprepared by mixing cyclopolydimethyl-~iloxanes, cyclopolymethylvinylsiloxanes, vinyl-endblocked polydimethyl~iloxane fluid, and KOH in a flask and heating as wa~ done for the hexenyl-substituted polymer noted above), O.19g of the platinum catalyst of Examples 1 to 10, a diorgano fumarate cure control additive (See Table II-Inhibitor), and 0.37g of the methylhydrogenpolysiloxane crosslinker of ~xamples 1 to 10.
For comparison, six paper coating compositions (Compositions i to n) were identically prepared, except containing the corresponding maleates instead of fumarates.
The bath life (at 25 or 40C.) and cure time (at 180F.=82.2C.) of each of the example coatings and comparison coatings were determined by the procedures noted above and the results are summarized in Table II. These examples illustrate the utility of the compositions of this invention as easily curable coating compositions which have useful bath lives. These examples, when considered with the disclosed comparison examples, also show the improved cure characteristics of the compositions of this invention, with respect to cure time and maintenance of cure time as the composition ages at room temperature and the viscosity increases, when the fumarate cure control additive is a diethyl fumsrate.
~30- ~30~5~8 TABLE II
COMPOSITIONS CONTAINING VINYL POLYMER
C9MP. INHIBITOR BATH-LIFE~HR.CURE-TIME.SEC.
IDENT* PPT 25C 40CINITIAL 2XVISCOSITY
11. DAF 10 6-21 105 i. DAM 10 100-166 165 12. DEF 20 22.5 50 13. " " 2.75 14. " " 48 - 50 15. " " 7 - 50 ~. DEM 20 70 180 16. MIF 4 1. 25 50 17. " 10 0. 75 90 18. " " 0.5 150 210 19. " 20 1.25 180 240 k. MIM 4 2.5 30 105 1. " 5 5.1 120 195 m. " 10 1-23 165 n. " " 8 75 * DAF = Diallyl fumarate. DAM = Diallyl maleate.
DEF = Diethyl fumarate. DEM = Diethyl maleate.
MIF = Methoxyisopropyl fumarate.
MIM = Methoxyisopropyl maleate.
PPT = Parts per thou~and parts of vinyl-substituted polymer.
Example 20 This example i9 presented to illustrate the slower reaction of the 5-hexenylsilyl unit toward SiH in the presence of diethyl fumarate compared to the same reaction mixture containing no added inhibitor. In this experiment~
model compounds, instead of polymers, were used so that the rate of the reaction could be monitored more easily.
The reactivity rates were compared by glc chromatograph analysis of mixtures of one-mol portions of HexMe2SiCl and Me3SiOMeHSiOSiMe3, where Hex denotes the ~-30~3508 5-hexenyl radical and Me denotes the methyl radical. The mixtures contained 7 mg Pt per mol of SiH compound. Platinum was added as a ~oluble complex of chloroplatinic acid and divinyltetramethyldisiloxane.
When the reaction was conducted at-60C. in the ab~ence of an inhibitor for the platinum catalyst 80~/o of the HexMe2SiCl was hydrosilylated in 10 minutes. Contrastingly, when the reaction was conducted in the presence of a one-mol portion of diethyl fumarate at 75C. only 22% of the HexMe2SiCl, and ~ubstantially none of the fumarate, was hydrosilylated in 30 minutes.
When diethyl fumarate alone was reacted with Me3SiOMeHSiOSiMe3 in the presence of the platinum catalyst at 100C 15% and 62% thereof wa9 hydrosilylated in 30 minutes and in 3 hours, re~pectively. Contrastingly, diethyl maleate undergoes only 44% hydro~ilylation in 3 hours.
ExamPle 21 This example is presented to illustrate the utility of the composition and method of this invention. S2S kraft paper was ooated with the composition of Example 6 and the applied coating was heated to 82C. (180F.) for 30 seconds to fully cure the coating.
The cured coating was immediately laminated with an acrylic athesive (GMS-263; Monsanto, St. Louis, MO.). The adhesive solution was applied to the coating at a wet thickness of 3 mils using a drawdown bar. The applied adhesive was air-dried at room temperature for one minute, heated at 70C. for one minute and the cooled to room temperature for one minute. A sheet of 60 pound matte litho was applied to the dried adhesive and the resulting laminate wa~ pressed with a 4.5 pound rubber-coated roller. The test laminate was then aged at room temperature and at 70C. and cut into 1 inch strips.
* Trademark Adhesive release testing was done by pulling the substrate/coating from the matte/adhesive at an an~le ~f 180 degrees and at a rate of 12, 78, 400 and 4000 inches per minute. The force needed to separate the adhesive/coating interface was noted several times during the separation and adhesive release was noted as an average of the several readings.
The release values were 40.5, 83.5, 113 and 109 g/in for pull speeds of 12, 78, 400 and 4000 in/min, respectively. This example shows that a composition of this invention having a pot life of 24 hours at room temperature can be rapidly cured at a moderate temperature to such an extent that the resulting coating not only does not experience acrylic weld with an adhesive applied in an in-line fashion, but will provide what is regarted as a premium release level, i.e., 100 g/in. Slightly higher release levels were obtained when the coating was cured at 150F. for 60 seconds and identically laminated, aged and pulled.
When this test was performed with polyethylene coated paper, instead of S2S kraft, the coating needed 90 seconds at 150F. to achieve full cure; however, the acrylic adhesive was released without acrylic weld and at premium levels.
DEF = Diethyl fumarate. DEM = Diethyl maleate.
MIF = Methoxyisopropyl fumarate.
MIM = Methoxyisopropyl maleate.
PPT = Parts per thou~and parts of vinyl-substituted polymer.
Example 20 This example i9 presented to illustrate the slower reaction of the 5-hexenylsilyl unit toward SiH in the presence of diethyl fumarate compared to the same reaction mixture containing no added inhibitor. In this experiment~
model compounds, instead of polymers, were used so that the rate of the reaction could be monitored more easily.
The reactivity rates were compared by glc chromatograph analysis of mixtures of one-mol portions of HexMe2SiCl and Me3SiOMeHSiOSiMe3, where Hex denotes the ~-30~3508 5-hexenyl radical and Me denotes the methyl radical. The mixtures contained 7 mg Pt per mol of SiH compound. Platinum was added as a ~oluble complex of chloroplatinic acid and divinyltetramethyldisiloxane.
When the reaction was conducted at-60C. in the ab~ence of an inhibitor for the platinum catalyst 80~/o of the HexMe2SiCl was hydrosilylated in 10 minutes. Contrastingly, when the reaction was conducted in the presence of a one-mol portion of diethyl fumarate at 75C. only 22% of the HexMe2SiCl, and ~ubstantially none of the fumarate, was hydrosilylated in 30 minutes.
When diethyl fumarate alone was reacted with Me3SiOMeHSiOSiMe3 in the presence of the platinum catalyst at 100C 15% and 62% thereof wa9 hydrosilylated in 30 minutes and in 3 hours, re~pectively. Contrastingly, diethyl maleate undergoes only 44% hydro~ilylation in 3 hours.
ExamPle 21 This example is presented to illustrate the utility of the composition and method of this invention. S2S kraft paper was ooated with the composition of Example 6 and the applied coating was heated to 82C. (180F.) for 30 seconds to fully cure the coating.
The cured coating was immediately laminated with an acrylic athesive (GMS-263; Monsanto, St. Louis, MO.). The adhesive solution was applied to the coating at a wet thickness of 3 mils using a drawdown bar. The applied adhesive was air-dried at room temperature for one minute, heated at 70C. for one minute and the cooled to room temperature for one minute. A sheet of 60 pound matte litho was applied to the dried adhesive and the resulting laminate wa~ pressed with a 4.5 pound rubber-coated roller. The test laminate was then aged at room temperature and at 70C. and cut into 1 inch strips.
* Trademark Adhesive release testing was done by pulling the substrate/coating from the matte/adhesive at an an~le ~f 180 degrees and at a rate of 12, 78, 400 and 4000 inches per minute. The force needed to separate the adhesive/coating interface was noted several times during the separation and adhesive release was noted as an average of the several readings.
The release values were 40.5, 83.5, 113 and 109 g/in for pull speeds of 12, 78, 400 and 4000 in/min, respectively. This example shows that a composition of this invention having a pot life of 24 hours at room temperature can be rapidly cured at a moderate temperature to such an extent that the resulting coating not only does not experience acrylic weld with an adhesive applied in an in-line fashion, but will provide what is regarted as a premium release level, i.e., 100 g/in. Slightly higher release levels were obtained when the coating was cured at 150F. for 60 seconds and identically laminated, aged and pulled.
When this test was performed with polyethylene coated paper, instead of S2S kraft, the coating needed 90 seconds at 150F. to achieve full cure; however, the acrylic adhesive was released without acrylic weld and at premium levels.
Claims (9)
1. A curable composition comprising (A) an organosilicon compound having an average of from one to three silicon-bonded monovalent radicals per silicon atom selected from the group consisting of hydro-carbon and halohydrocarbon radicals, there being an average of at least two of said monovalent radicals, per molecule of Component (A), selected from the group consisting of olefinic hydrocarbon radicals, the remaining silicon valences thereof being satisfied by divalent radicals free of aliphatic unsaturation selected from the group consisting of oxygen atoms, hydrocarbon radicals, hydrocarbon ether radicals, halohydrocarbon ether radicals and halohydrocarbon radicals, said divalent radicals linking silicon atoms, (B) an organohydrogensilicon compound containing at least two silicon-bonded hydrogen atoms per molecule thereof and an average of from one to two silicon-bonded monovalent radicals free of aliphatic unsaturation, per silicon atom, selected from the group consisting of hydrocarbon and halohydrocarbon radicals, the remaining silicon valences thereof being satisfied by divalent radicals free of aliphatic unsaturation selected from the group consisting of oxygen atoms, hydrocarbon radicals, hydrocarbon ether radicals, halohydrocarbon ether radicals and halo-hydrocarbon radicals, said divalent radicals linking silicon atoms, (C) an amount of a platinum-containing catalyst sufficient to accelerate a reaction of said silicon-bonded olefinic hydrocarbon radicals with said silicon-bonded hydrogen atoms at room temperature, and (D) an amount of an inhibitor compound for the platinum-containing catalyst sufficient to retard said reaction at room temperature but insufficient to prevent said reaction at elevated temperature, said inhibitor compound having the formula wherein each R1 denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 carbon atoms, each D
denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of 0 or 1, the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/100 to 100/1.
denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of 0 or 1, the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/100 to 100/1.
2. A composition in accordance with claim 1 wherein component (A) is an organopolysiloxane having the average unit formula RC2SiO(4-c)/2 wherein R2 denotes said monovalent radicals and c has a value of from 1 to 3, and component (B) is an organohydrogenpolysiloxane having the average unit formula Re3HfSio(4-e-f)/2 wherein R3 denotes said monovalent radical free of aliphatic unsaturation, f has a value of from greater than 0 to 1 and the sum of e plus f has a value of from 1 to 2.
3. A composition in accordance with claim 2 wherein component (A) has the formula XMe2SiO(Me2SiO)b(MeXSiO)dSiMe2X and component (D) has the formula wherein Me denotes methyl, X denotes a monovalent radical selected from the group consisting of olefinic hydrocarbon radicals having from 2 to 12 carbon atoms and R radicals, an average of at least two X radicals per molecule of Component (A) being olefinic hydrocarbon radicals, R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation having from 1 to 20 carbon atoms, b and d have average values of zero or more, and the sum of b plus d has a value sufficient to provide a viscosity at 25°C.
of at least 25 millipascal-seconds for the Component (A).
of at least 25 millipascal-seconds for the Component (A).
4. A composition in accordance with claim 3 wherein component (A) has the formula HexMe2SiO(Me2SiO)b(MeHexSiO)dSiMe2Hex, wherein Hex denotes CH2=CHCH2CH2CH2CH2-, component (B) has the formula YMe2SiO(Me2SiO)p(MeYSiO)qSiMe2Y, wherein Y denotes a hydrogen atom or Me, an average of at least two Y radicals per molecule of component (B) being hydrogen atoms, p and q have average values of zero or more, the sum of p plus q has a value sufficient to provide a viscosity at 25°C. of from 1 to 100 millipascal-seconds for the Component (s) and b, d and Me are as defined in claim 3, component (C) comprises a vinylsiloxane complex of chloro-platinic acid, and component (D) is diallyl fumarate.
5. A composition in accordance with claim 3 wherein component (A) has the formula ViMe2SiO(Me2SiO)b(MeViSiO)dSiMe2Vi, wherein Vi denotes CH2=CH-, component (B) has the formula YMe2SiO(Me2SiO)p(MeYSiO)qSiMe2Y, wherein Y denotes a hydrogen atom or Me, an average of at least two Y radicals per molecule of Component (B) being hydrogen atoms, p and q have average values of zero or more, the sum of p plus q has a value sufficient to provide a viscosity at 25°C. of from 1 to 100 millipascal-seconds for the component (B) and b, d and Me are as defined in claim 3, component (C) comprises a vinylsiloxane complex of chloro-platinic acid, and component (D) is diethyl fumerate.
6. A process for rendering a solid surface of a substrate less adherent to materials that normally adhere thereto, said process comprising (I) applying to said solid surface a coating of a liquid curable composition comprising (A) an organopolysiloxane compound having the formula XMe2SiO(Me2SiO)b(MeXSiO)dSiMe2X, wherein Me denotes methyl, X denotes a monovalent radical selected from the group consisting of olefinic hydrocarbon radicals having from 2 to 12 carbon atoms and R radicals, an average of at least two X radicals per molecule of Component (A) being olefinic hydrocarbon radicals, R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation having from 1 to 20 carbon atoms, b and d have average values of zero or more, and the sum of b plus d has a value sufficient to provide a viscosity at 25°C. of at least 25 millipascal-seconds for the Component (A), (B) an organohydrogenpolysiloxane compound bearing at least two silicon-bonded hydrogen atoms per molecule thereof and having the average unit formula Re3HfSiO(4-e-f)/2 wherein R3 denotes a monovalent hydrocarbon or halohydro-carbon radical free of aliphatic unsaturation, f has a value of from greater than 0 to 1 and the sum of e plus f has a value of from 1 to 2, (C) an amount of a platinum-containing catalyst sufficient to accelerate a reaction of said silicon-bonded olefinic hydrocarbon radicals with said silicon-bonded hydrogen atoms at room temperature, and (D) an amount of an inhibitor component having the formula wherein R1 denotes a monovalent hydrocarbon radical having from 1 to 6 carbon atoms, each D denotes, independently, an alkylene radical having from 2 to 4 carbon atoms and each a has an average value of 0 or 1; the amounts of Components (A) and (B) being sufficient to provide a ratio of the number of silicon-bonded hydrogen atoms to the number of silicon-bonded olefinic hydrocarbon radicals of from 1/2 to 1.5/1, and (II) heating the applied coating for a period of time sufficient to cure the applied coating.
7. A process according to claim 6 wherein the substrate is a flexible sheet material.
8. A process according to claim 7 further comprising (III) applying a pressure sensitive adhesive composition to the cured applied coating.
9. A process according to claim 7 wherein the flexible sheet material is paper.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IN407/MAS/88A IN171585B (en) | 1988-05-06 | 1988-06-15 | |
| IN805MA1991 IN179453B (en) | 1988-05-06 | 1991-10-23 |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67,747 | 1987-06-29 | ||
| US07/067,747 US4774111A (en) | 1987-06-29 | 1987-06-29 | Heat-curable silicone compositions comprising fumarate cure-control additive and use thereof |
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| CA1308508C true CA1308508C (en) | 1992-10-06 |
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| CA 566102 Expired - Lifetime CA1308508C (en) | 1987-06-29 | 1988-05-06 | Heat-curable silicone compositions comprising fumarate cure-control additive and use thereof |
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| Country | Link |
|---|---|
| US (1) | US4774111A (en) |
| EP (1) | EP0297746B1 (en) |
| JP (1) | JPS6487661A (en) |
| KR (1) | KR960012462B1 (en) |
| AU (1) | AU607779B2 (en) |
| CA (1) | CA1308508C (en) |
| DE (1) | DE3887393T2 (en) |
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| WO2012078594A1 (en) | 2010-12-08 | 2012-06-14 | Dow Corning Corporation | Siloxane compositions suitable for forming encapsulants |
| CN103328575A (en) | 2010-12-08 | 2013-09-25 | 道康宁公司 | Siloxane compositions including titanium dioxide nanoparticles suitable for forming encapsulants |
| KR20140054058A (en) | 2011-08-18 | 2014-05-08 | 모멘티브 퍼포먼스 머티리얼즈 게엠베하 | Irradiating and molding unit |
| CN104640681B (en) | 2012-06-11 | 2017-11-17 | 迈图高新材料集团 | Method for preparing plastics composite shaped body |
| JP6435453B2 (en) | 2014-06-27 | 2018-12-12 | ダウ （シャンハイ） ホールディング カンパニー リミテッド | Silicone release coating composition and low release force emulsion silicone release coating for film and paper with cured release coating |
| WO2018112911A1 (en) | 2016-12-23 | 2018-06-28 | Dow (Shanghai) Holding Co., Ltd. | Polyorganosiloxane release coating and method for its preparation and use |
| US11685844B2 (en) | 2019-05-16 | 2023-06-27 | Dow Silicones Corporation | Polysiloxane controlled release additive, method for the preparation thereof, and release coating composition |
| WO2023227714A1 (en) | 2022-05-25 | 2023-11-30 | Momentive Performance Materials Gmbh | New substituted phosphite transition metal compounds |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL129346C (en) * | 1966-06-23 | |||
| US3759968A (en) * | 1971-05-17 | 1973-09-18 | Gen Electric | Silyl maleates and polysiloxane maleates |
| US3882083A (en) * | 1973-11-21 | 1975-05-06 | Gen Electric | Latent addition curable organopolysiloxane compositions |
| US3989667A (en) * | 1974-12-02 | 1976-11-02 | Dow Corning Corporation | Olefinic siloxanes as platinum inhibitors |
| US4208471A (en) * | 1978-12-22 | 1980-06-17 | The Gillette Company | UV-Curable siloxane razor blade lacquers |
| US4256870A (en) * | 1979-05-17 | 1981-03-17 | General Electric Company | Solventless release compositions, methods and articles of manufacture |
| US4337332A (en) * | 1981-04-09 | 1982-06-29 | Minnesota Mining And Manufacturing Company | Latently curable organosilicone compositions |
| US4340647A (en) * | 1981-05-22 | 1982-07-20 | General Electric Company | Vinyl gum cure accelerators for addition-cure silicone |
| JPS6054991B2 (en) * | 1982-04-02 | 1985-12-03 | ト−レ・シリコ−ン株式会社 | Organopolysiloxane composition |
| US4472563A (en) * | 1984-02-06 | 1984-09-18 | Dow Corning Corporation | Heat curable silicones having improved room temperature stability |
| US4562096A (en) * | 1984-12-24 | 1985-12-31 | Dow Corning Corporation | Heat-curable silicone compositions, use thereof and stabilizer therefor |
| US4609574A (en) * | 1985-10-03 | 1986-09-02 | Dow Corning Corporation | Silicone release coatings containing higher alkenyl functional siloxanes |
-
1987
- 1987-06-29 US US07/067,747 patent/US4774111A/en not_active Expired - Lifetime
-
1988
- 1988-05-06 NO NO881974A patent/NO881974L/en unknown
- 1988-05-06 CA CA 566102 patent/CA1308508C/en not_active Expired - Lifetime
- 1988-06-13 DE DE19883887393 patent/DE3887393T2/en not_active Expired - Fee Related
- 1988-06-13 EP EP19880305361 patent/EP0297746B1/en not_active Expired - Lifetime
- 1988-06-27 FI FI883075A patent/FI96773C/en not_active IP Right Cessation
- 1988-06-28 AU AU18473/88A patent/AU607779B2/en not_active Ceased
- 1988-06-28 KR KR1019880007807A patent/KR960012462B1/en not_active IP Right Cessation
- 1988-06-29 JP JP15959888A patent/JPS6487661A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| NO881974D0 (en) | 1988-05-06 |
| EP0297746A2 (en) | 1989-01-04 |
| DE3887393T2 (en) | 1994-08-04 |
| EP0297746A3 (en) | 1989-12-27 |
| KR960012462B1 (en) | 1996-09-20 |
| AU607779B2 (en) | 1991-03-14 |
| FI883075A0 (en) | 1988-06-27 |
| FI96773B (en) | 1996-05-15 |
| KR890000600A (en) | 1989-03-15 |
| FI883075A (en) | 1988-12-30 |
| FI96773C (en) | 1996-08-26 |
| JPH0587100B2 (en) | 1993-12-15 |
| EP0297746B1 (en) | 1994-01-26 |
| DE3887393D1 (en) | 1994-03-10 |
| US4774111A (en) | 1988-09-27 |
| NO881974L (en) | 1988-12-30 |
| AU1847388A (en) | 1989-01-05 |
| JPS6487661A (en) | 1989-03-31 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |