CA2241533A1 - Partially cross-linked microspheres - Google Patents
Partially cross-linked microspheres Download PDFInfo
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- CA2241533A1 CA2241533A1 CA002241533A CA2241533A CA2241533A1 CA 2241533 A1 CA2241533 A1 CA 2241533A1 CA 002241533 A CA002241533 A CA 002241533A CA 2241533 A CA2241533 A CA 2241533A CA 2241533 A1 CA2241533 A1 CA 2241533A1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/44—Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
- C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
- C08F20/10—Esters
- C08F20/12—Esters of monohydric alcohols or phenols
- C08F20/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
- C08F20/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09J133/08—Homopolymers or copolymers of acrylic acid esters
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09J133/10—Homopolymers or copolymers of methacrylic acid esters
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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
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
- C08L2205/18—Spheres
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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
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
- Y10T428/24893—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material
Abstract
An adhesive composition is provided comprising: (a) a plurality of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4-C14 alkyl (meth)acrylate monomer and optionally at least one comonomer and have a solvent soluble portion that is 30-98 % of the microsphere.
Description
CA 02241~33 1998-06-24 W O 97126286 PCTrUS96/18522 Partially Crosslinked Microspheres Technical Field This invention relates to a microsphere adhesive and in particular to a microsphere adhesive that exhibits enh~nced adhesion to substrates while le~ g 5 repositionable.
R~kground of the Invention Repositionable adhesives are comrnonly used for temporary messaging or signage in the home and office environment. This type of product is typified by Post-it@) brand notes. When using such a product it is desired that the note adhere to a 10 variety of surfaces yet be cleanly removable from the surface without leaving adhesive residue, while m~int~ining the repositionable characteristics of the notes.
References can be cited for the prepal ~lion and/or use of inherently tacky, polymeric microsphere adhesives (~efor example, U. S. Patent Nos. 3,691,140 and 4,166,152). Such rnicrosphere adhesives are typically used for the commonly 15 recognized repositionable notes.
Various investigators have sought to improve or further enh~nce adhesion to surfaces other than the comrnonly used paper surfaces. Various techniques have been used, such as chemical modification of the microsphere, alteration of the adhesive composition, inrln-ling the use of binders and the like, or process modifications. For 20 example, U.S. Patent No. 5,053,436 describes a hollow microsphere, wherein the rnicrosphere provides increased re~ nce to adhesive transfer and an increased adhesion level. Along the same line, U.S. Patent No. 4,988,567 describes microspheres having multiple small voids.
In yet another attempt, U.S. Patent No. 5,326,842 describes a dual 25 polymerization process wherein high-tack adhesives are produced wherein a chain ll ~nsrer agent is used in the first step (suspension polymerization) and the second step (çtn~ ion polymerization) provides stability of the final material.
However, to date, control of the solvent soluble portion of the microsphere to produce a stable repositionable rnicrosphere adhesive with enhanced adhesion has not 30 been contemplated.
CA 02241~33 1998-06-24 WO 97126286 PCT~US96118522 Summary of the Invention Briefly, in one aspect of the present invention, a microsphere adhesive composition is provided comprising a 30-98% solvent soluble portion.
In particular, the present invention comprises a microsphere adhesive 5 composition co".~"is.l~g:
(a) a plurality of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of react~ntc comprising polymerizable starting materials comprising at least one C4-Cl4 alkyl (meth)acrylate monomer and optionally at least one comonomer, (b) optionally, a polymeric st~9bili~r in an amount of beLween about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres, preferably about 0.1 to about 1.5 parts by weight per 100 parts by weight of the microspheres;
(c) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres, preferably no greater than 3 parts by weight and most pl ~re.ably in the range of 0.5 to about l . 5 parts by weight per 100 parts by weight of the microspheres;
(d) a modifier, wherein the modifier can be at least one of a chain tl ansrer agent, a tackifier, a solvent or the like in an amount that is sufficient to provide microspheres with a solvent soluble portion in the range of 30-98%, preferably in the range of 40-95%; and (e) an initiator present in amounts ranging from 0.1 to applu~hl,ately 2 parts by weight per 100 parts by weight of the polymerizable monomer starting material.
As used in this application, the notation "(meth)acrylate" refers to acrylate and methacrylate.
A modifier may be used to regulate the solvent soluble portion of the microspheres and it is added to the polymerization mixture in an amount sufficient to provide a solvent soluble portion that is in the range of 30-98%, preferably in the range of 40-95%. Various modifiers may be used within the scope of this invention and the amounts used are those that sufficiently provide the microspheres ~,vith a solvent soluble portion. Such amounts would range, for example for solvents from 1-30%, for tackifiers from 1-30% and for chain transfer agents, up to about 0.15%
CA 02241~33 1998-06-24 W O 97126286 PCT~US96/18522 Particularly useful modifiers are chain transfer agents. To control the molecular weight of the polymer being formed in the microsphere a chain transferagent or modifier is used. Many halogen-and sulfur-co~ organic compounds function well as chain 1. arl~rer agents in free radical polymerizations. Non-limiting 5 examples of such agents are: carbon tetlabl~),lude, carbon tetrachloride, dodec~n~lhiol, iso-octylthioglycolate, butyl mercaptal1, and tertiary-dodecyl ealJIan. Particularly useful chain ~l~nsrel agents are long chain meJ.~I~t~ns, such as clodec~neth;cl. The amount of chain l.~r~, agent suitable for microsphere polymerizations is calculated on a weight basis to the entire polymerizable content.
10 The chain l~ rer agent is prefe.ubly added at up to about 0.15%, more p-efe.ably up to about 0.12% and most preferably up to about 0.08%. These levels are adequate to provide a solvent soluble polymer component in the microsphere of up to about 98%.
Other useful modifiers are solvents. Examples of which are but not lin~ited to aliphatic or aromatic solvents such as heptane, ben_ene, toluene and the like; alcohols 15 such as methanol, isopropyl alcohol, and the like; and ketones such as acetone, methyl ethyl ketone and the like. The amount of solvent suitable for microsphere poly..lc-i~a~ions is calcul~ted on a weight basis to the entire polymerizable content.
The solvent is prt;Çelàbly added at up to about 30%, more preferably up to about 15%
and most prefe.ably up to about 5%. These levels are adequ~te to provide a solvent soluble polymer component in the microspheres of up to about 98%.
Still other useful modifiers include t~c~ifiers and/or plasticizers. Examples ofwhich are but not limited to: hydrogenated rosin esters commercially available from such companies as Hercules, Inc. under the tradçnqmes of ForalTM, Regalrez~ and PentalynTM. Tackifying resins also include those based on t-butyl styrene. Useful pl~tici7Prs include but are not limited to dioctylphth~l~tel 2 ethylhexyl phosphate, tricresyl phosphate, mineral oil and the like. The tackifier and/or p!~ctici7er are preferably added at up to about 30%, more preferably up to about 15% and most preferably up to about 5%. These levels provide a solvent soluble polymer component in the microsphere of up to about 98%.
In another aspect of the present invention a one step suspension polyrnerizationprocess is provided for preparing polymeric elastomeric m~crospheres comprising the steps of:
CA 02241~33 1998-06-24 (a) stirring or a~it~tine a mixture comprising polymerizable monomer starting materials comprising:
(i) at least one C4-C14 alkyl (meth)acrylate monomer and, optionally at least one comono.,~., (ii) an initiator for the polymerizable monomer starting materials present in amounts ranging from 0.1 to approxin~àlely 2 parts per weight per 100 parts by weight of the poly.".,- .~able monomer starting materials;
(iii) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monon, starting materials;
(iv) a surfactant in an amount no greater than about S parts by weight per 100 parts by weight of polymerizable monomer, preferably no greater than about 3 parts by weight and most prefe.l.bly in the range of 0.5 to 1 5 parts by weight; (v) water to form an oil in water suspension; and (vi) a modifier in an amount sufficient to provide a solvent soluble portion in the range of 30-98%; and (b) polymerizing the (meth)acrylate monulll~l(s) and the comonomer(s), if pr~se..l, wl.e~ cill microspheres are provided.
In yet another aspect, the present invention provides a two-step suspension 20 polymerization process for pl epar;i g polymeric elastomeric microspheres from polymerizable monomer stating materials, wherein the process comprising the steps of (a) stirring or ~it~tin~ a mixture compli~;.-g:
(i) at least one C4-C14 alkyl (meth)acrylate monomer;
(ii) an initiator for the monomer present in amounts ranging from 0 1 to 25 approx;~ely 2 parts per weight per 100 parts by weight ofthe polyllleli~able monomer starting materials;
(iii) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iv) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight ofthe polymerizable monomer starting materials, CA 02241~33 1998-06-24 W O 97126286 PCT~US96/18S22 preferably no greater than 3 parts by weight and most preferably in the range of 0. 5 to 2 parts by weight;
(v) a modifier in an amount sufficient to provide a solvent soluble portion in the range of 30-98%; and (vi) water to form an oil in water suspension;
(b) at least partially polymerizing the polyl.,e,i~able monomer starting materials;
(c) adding to the suspension at least one comonomer; and (d) contin~ing the polyrnerization of the polymerizable monomer starting materials; wherein microspheres are provided.
The present invention also provides in another aspect a sheet material comprising a backing and a coating of repositionable pressure sensitive adhesivedescribed above is coated on at least one portion of at least one major surface.Advantageously, the present invention provides a rnicrosphere-based pressure sensitive adhesive having a high solvent soluble fraction that adheres to rough surfaces such as fabric, removes cleanly, and exhibits the ability to be reapplied multiple times if desired. Even with this ~nh~nced adhesion to rough surfaces the microsphere adhesive will still adhere non-destructively to fragile surfaces such as paper. Furthermore, the microsphere adhesive of this invention is prepd-ed according to resource efficient methods.
Several features of the adhesive of the present invention provide a number of desirable advantages that have heretofore been unavailable. ~or example several advantages include, (a) improved adhesion to various surfaces (textured surfaces, fabric, wood, painted surfaces, glass, vinyl, etc), (b) high adhesion without fiber pick or substrate damage on removal from substrates, (c) adhesive strength that remains col~slal~l or slightly builds after a period of time, and (d) a microsphere adhesive that adheres to a substrate or b~c~ing and easily removes from applied surfaces without llallsrwling or leaving an adhesive residue on the applied surface.
Description of the Preferred Embodiment(s) The microspheres obtained in the present invention are the reaction product of (a) at least one alkyl (meth)acrylate ester wherein the alkyl group conlaills four to about 14 carbon atoms, p.ef~-ably four to about 10 carbon atoms and, optionally, a CA 02241~33 1998-06-24 W O 97/26286 PCTAUS96tl8522 comonomer. The comonomer, if present may be nonpolar, ionic polar or rnixtures of such monomers.
Useful alkyl (meth)acrylate mon~ are those monofunctional unsaturated (meth)acrylate esters, the alkyl groups of which have from 4 to 14 carbons atoms.
5 Such (meth)acrylates are oleophilic, water d.spel~iblc, and are ess~nti~lly water insoluble. Furthel~..ole, useful (meth)acrylates are those that as homopolyrners, generally have a glass transition te--",c~ ature below about -20~C, or if a combination of monomers is used, such a combination would produce a copolymer or terpolymer generally having a glass trprlcitifm tclup~al~re below about -20~C. Nonlimiting 10 examples of such (meth)acrylates in~l...ie~ but are not limited to, isooctyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isodecyl methacrylate, t-butyl acrylate, t-butyl methacrylate, isobornyl acrylate, methylmeth~crylate, isononyl acrylate, isodecyl acrylate and the like, and the co...binalion thereo~
Preferred alkyl (meth)acrylate monomers include isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, sec-butyl acrylate and mixtures thereof.
Vinyl ester monomers suitable for use in the present invention include but are not limited to: vinyl 2-ethylheY~oate, vinyl caprate, vinyl laurate, vinyl pelargonate, vinyl hexanoate, vinyl propionate, vinyl dec~noate, vinyl act~noate, and other monofunctional unsaturated vinyl esters of linear or branched carboxylic acids co~ g l to 14 carbon atoms, which as homopolymers have glass transition temperatures below about -10~C. ~lerel-~d vinyl ester monomers include vinyl laurate, vinyl caprate, vinyl 2-ethylh~ no~le, and mixtures thereof.
Additional other vinyl monomers which, as homopolymers, have glass transition telll?c~al~lres higher than about -10~C to 0~C, such as vinyl acetate, acrylonitrile, llu~Lures thereof and the like, may optionally be utilized in conjunction with one or more of the acrylate, meth~crylate and vinyl ester monomers provided the glass transition temperature ofthe res~llt~nt polymer is below about -10~C.
Suitable comonomers include nonpolar, ionic, polar monomers and mixtures thereof. In addition to using one or more acrylate monomers as a comonomer, as described above, the following are non-limiting examples of comonomers:
W 097/26286 PCTrUS96/18522 (A) ionic comonomers, such as sodium meth~crylate, ammonium acrylate, sodium acrylate, (I) l~i",~Lhylamine p-vinyl b~ rle, (II) 4,4, 9-trimethyl-4-azonia-7-oxo-8-oxa-dec-9-ene-1-sulphonate, (III) N,N-dimethyl-N-(,B-mPth~crylo~y~thyl) ammonium propionate betaine, (IV) l~ hylamine met~ rylimide, (V) 1, l -dimethyl-5 1(2,3-dihydroxypropyl)amine meth~ ,fylimide; any zwitterionic monomer and the like;
~ B) non-polar comonomers include but are not lirnited to, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, isodecyl mP.th~~rylate, t-butyl acrylate, t-butyl meth~rrylate, isobornyl acrylate, octyl acrylamide, metl"~ rylate, isononyl acrylate, isodecyl acrylate, styrene and the 10 like, and the co",bil,alion thereo~
(C) Polar comonomers may or may not contain a dissociable hydrogen.
Examples of suitable polar comonomers include organic carboxylic acids Col~ JIiSillg 3 to about 12 carbon atoms and having generally 1 to about 4 carboxylic acid moieties.
Nonl;,~ e examples of such monomers acrylic acid, methacrylic acid, itaconic acid, 15 fumaric acid, crotonic acid, maleic acid, ~-carboxyethylacrylate and the like. In addition suitable polar comonomers include acrylamide, methacrylamide, 2-h~dro~yelllyl acrylate, and the like.
In addition, one class of suitable comonomers are amino-functional monomers having a nucleus or portion ofthe nucleus ofthe general formula (a):
o CH2=CHRl--C--L--R2--(NR3R4)X
(1) wherein R, is--H,--CH3,--CH2CH3, cyano or carboxymethyl;
R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms;
R3 and R4 are independently H or an alkyl group containing 1 to about 12 carbon atoms or an arylalkyl group or together fonn a cyclic or heterocyclic moiety;
L is carbon-carbon bond, O, NH or S; and x is an integer of 1 to 3.
Nonlimitin~ examples of comonomers according to formula (1) include N, N-dimethyl-aminoethyl(methyl)acrylate, N,N-dimethylaminopropyl-(meth)acrylate, t-butylaminoethyl(methyl)acrylate and N,N-diethylaminoacrylate.
W O 97/26286 PCTrUS96/18522 Another class of suitable comonomers are comonomers having a nucleus or portion of the nucleus of the general formula (2):
o CH2=CHRl--C--L--R2(R~
(2) wherein R, is H,--CH3,--CH2CH3, cyano or carboxymethyl;
R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms;
R5 is -O-, alkylene oxide coJnp~ g 1 to 5 carbon atoms, or phenoxy oxide, wherein the alkylene oxide would in~lude~ -CH20-, -CH2CH20-, -CH2(CE~)CH30-, and the like;
R6 is H, -C6H4OH, or -CH3 L is a carbon-carbon bond, O, NH or S; and x is an integer with the proviso that when R5 is -O-, x is an integer of 1-3.
Nonlimitin~ examples of comonomers according to formula (2) inc}ude Lydloxye~llyl (meth)acrylate, glycerol mono(meth)acrylate and 4-hydroxybutyl (meth)acrylate, acrylate termi~l~ted pol(ethylene oxide), mçth~crylate termin~ted poly(ethylene oxide); methoxy poly(ethylene oxide) meth~crylate; butoxy poly(ethylene oxide) m~th~crylate; acrylate termin~ted poly(ethylene glycol); methacrylate termin~ted poly(ethylene glycol); methoxy poly(ethylene glycol) methacrylate; butoxy poly(ethylene glycol) mPt~erylate and mixtures thereof.
Yet another class of suitable comonomers are amido-functional monomers having a nucleus or portion of the nucleus of the general formula (3):
o CH2=CHRI--C--NR3R4 (3) wherein R~ is H,--CH3, -CH2CH3, cyano or carboxymethyl; and R3 R4 are independently H or an alkyl group cont~ining 1 to about 12 carbons or an arylalkyl group or together form a cyclic or heterocyclic moiety.
Nonlimiting examples of comonomers according to formula (3) include N-vinyl 30 pyrrolidone, N-vinyl caprolactom acrylamide or N, N-dimethyl acrylamide.
W O 97/26286 PCTrUS96/18522 Nonlimiting examples of other suitable comonomers that do not fall within the above classes but are within the scope of permissible comononers include (meth)acrylonitrile, furfuryl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate, 2-vinyl pyridine, and 4-vinyl pyridine.
Typically, when a co,nonor"er is present, the relative amounts by weight of the alkyl (meth)acrylate monomer(s) and the comonomer is in the range of about 99.5/0.5 to 75/25, and preferably is in the range of 9812 to 92/8.
A modifier may be used to regulate the solvent soluble portion of the microspheres and it is added to the polyll,e.i~lion mixture in an amount sufficient to provide a solvent soluble portion that is in the range of 30-98%, preferably in the range of 40-95%. Various modifiers may be used within the scope of this invention and the amounts used are those that sufflciently provide the microspheres with a solventsoluble portion. Such amounts would range, for example for solvents from 5-30%, for tackifiers and/or pl~sti~i7ers from 1-30% and for chain transfer agents, up to about 0.15%.
Particularly useful modifiers are chain tran~r~l agents. To control the molecular weight of the polymer being formed in the microsphere it is desirable to use a chain transfer aBent or modifier. Many halogen-and sulfur-co.~ in~. organic compounds function well as chain l, ans~.- agents in free radical polymerizations Non-limiting examples of such agents are: carbon tell~bro-,lide, carbon tetrachloride, dodec~nethiol, iso-octylthioglycolate, butyl ,.,~-,aptan, and tertiary-dodecyl mel~a~tan. In this invention it is efficacious to employ long chain merca~lans such as dodec~net~iol. The amount of chain l-~ns~r agent suitable for these microsphere polymerizations is c~lc~ ted on a weight basis to the entire polymerizable content.
The chain transfer agent is ple~-~bly added at up to about 0.15% more preferably up to about 0.12% and most preferably up to about 0.08%. These levels are fldeq-l~te to provide a soluble polymer content in the microsphere of up to about 98%.
The microsphere adhesive composition may also contain a cro~.clin~ing agent.
Examples of useful crosslin~ing agents include, but are not limited to: mllltifilnctiona (meth)acrylate(s), e.g., butanediol diacrylate or hexanediol diacrylate or othermllltifilnctional crosslinkers such as divinylbenzene and mixtures thereof When used, crosslinker(s) is (are) added at a level of up to about 0.15 equivalent weight percent, W O 97126286 PCT~US96/18S22 preferably up to about 0.1 equivalent weight percent, of the total polymerizablecomposition with the proviso that the con~billalion of crosslin~in~ agent and modifier concentrations are chosen to obtain a microsphere with 30 to 98% solvent solubleportion.
The llhcrosp}ul es of the present invention are prepared by suspension poly."c.i a~ion using either a one-step or two-step process as described in detail below. Suspension polymerization is a procedure wherein a monomer is dispe. ~ed in a medillm (usually a~ueous) in which it is insoluble. The polymerization is allowed to proceed within the individual polymer dl~Fletc Monomer soluble free-radical 10 initiators are preferably used. The kinetics and the ecl.~ are those for the co~ ondi.l~ bulk polylll~l ;zalion under similar conditions of tel.lperhlllre and initiator conc~i"~ ion.
Initiators affecting polymerization are those that are norrnally suitable for free-radical pol~lne~ ion of acrylate monomers. Examples of such initiators include thermally-activated initiators such as azo compounds, hydroperoxides, peroxides and the like and photoinitiators such as benzophenone, benzoin ethyl ether and 2,2-~imethoxy-2 pheny3 acetophenone. Other suitable initiators include lauroyl peroxide and bis(t-butyl cyclohexyl)peroxy ~;call~ollale The initiator is present in a catalytically effective amount s.-fficient to bring about high monomer conversion in a predetermined time span and ttlllp~l alure range. Typically, the initiator is present in amounts ranging from 0.1 to appro~ul.lately 2 parts per weight per 100 parts by weight of the polyrnerizable monomer starting materials.
Parameters that affect the concenll alion of initiator employed include the typeof initiator and particular monomer and/or monomers involved. It is believed that catalytically effiective conce,llldlions range from about 0.1 to about 2 percent by weight ofthe total monomers and more preferably, from about 0.20 to about 0.70 percent by weight monomers and/or monomers.
Optionally, a polymeric stabilizer may be used. Advantageously, the presence of the stabilizer perrnits the use of relatively low amounts of surfactant while still obtaining microspheres.
Any polymeric stabilizer that effectively provides sufficient stabilization of the final polymerized droplets and prevents agglomeration within a suspension CA 02241~33 1998-06-24 W 097/26286 11 PCT~US96118522 polymerization process is useful in the present invention. When used, a polymeric stabilizer will typically be present in the reaction rnixture in an amount by weight of about 0.1 to about 3 parts by weight per 100 parts of polymerizable monomer, andmore plerel~bly will be present in an amount by weight of about 0.1 to about 1.5 parts S by weight per 100 parts of polyrnerizable monomer.
Fxenlpl~ry polymeric ~ ~L 'li7çrs indude salts of polyacrylic acids of greater than 5000 m~lecul~r weight average (for eY~rnrle, ammonium, sodium, lithium and potassium salts), carboxy modified polyacrylamides (for example, Cydn~..ne.TMA-370 from American Cyanamid), copolymers of acrylic acid and dimethylaminoethylmethacrylate and the like, polymeric quaternary amines (for example, General Analine and Film's GafquatlM 755, a quaternized polyvinyl-pyrollidone copolymer, or Union Carbide's "JR-4007', a quaternized amine substituted cellulosic), cellulosics, and carboxy-modified cellulosics (for example, Hercules' NatrosollM CMC Type 7L, sodium carboxy methycellulose).
Surf~ct~ntc will typically be present in the reaction mixture in an amount of nogreater than about 5 parts by weight per 100 parts by weight of polymerizable monomer, p[~f~l ably no greater than about 3 parts by weight, and most preferably in the range of 0. S to 1.5 parts by weight per 100 parts by weight of polymerizable monomer.
Useful surf~ct~ntc include anionic, cationic, nonionic or amphoteric surfactantsand include but are not lirnited to anionic surfr~t~nts, such as alkyl aryl sulfonates, for example sodium dodecylbenzene sulfonate and sodium decylbenzene, sodium and ammonium salts of alkyl sl.lf~tes, for examples sodium lauryl sulfate, and ammonium lauryl sulfate; nonionic surf~Lct~ntc, such as ethoxylated oleoyl alcohol and polyoxyethylene octylphenyl ether; and cationic surf~.t~ntc, such as a mixture of alkyl dimethylbenzyl ammonium chlorides wherein the alkyl chain contains from 10 to 18carbon atoms. Amphoteric surf- - t~nt.c are also useful in the present invention and include for example sulfobetaines, N-alkylaminopropionic acids, and N-alkybetaines.
To initiate the pOI~ ,. ;~lion reaGtion, a sufficient number of free radicals must be present. This may be achieved through severat means that are well known in the art, such as heat or radiation free-radical initiation. For example, heat or radiation can be applied to initiate the pol~,l,el izalion of the monomers, which is an exothermic CA 02241~33 1998-06-24 W O 97126286 PCTrUS96/18522 reaction. However, it is pl erel I ed to apply heat until thermal decomposition of the initiators gene,ales a s~fficient number offree radicals to begin the reaction. The tc~ )elal~lre at which this occurs varies greatly depen~ling upon the initiator used.
In addition, deoxyEçn~tion of the polymerization reaction mixture is often desirable. It is well known that oxygen dissolved in the reaction n~iAlule can inhibit polymerization and it is de~l ble to expel this dissolved oxygen. ~Ithoueh~ an inert gas bubbled into the reaction vessel or through the reaction mixture is an effective means of deo~ygel-alion, other techniques for deox~ n~l ;on that are conl~alil~le with suspension polymerization can be used. Typically, nitrogen is used to deo~ygenate, although any of the Group VIIIA (CAS version) inert gases are also suitable.
While specific time and stirring speed parameters are dependent upon monomers, and initiators, it is desirable to pl edis~,el ~e the reaction mixture until the reaction mixture reaches a state where the average monomer droplet size is between about 1 l~m and 300 llm and preferably between 20 llm and 70 ~m. The average particle size tends to decrease with increased and prolonged agitation of the reaction mixture.
~ererably, stirring and nitrogen purge are m~int~ined throughout the reaction period. Initiation is begun by heating the reaction mixture. Following polymerization, the reaction mixture is cooled.
In a one-step process both the alkyl (meth)acrylate monomer and any optional comonomer are present together in the suspension at the initiation of polymerization.
In a two-step process any optional comonomer is typically added after the initial exotherm resulting from polylll~liza~ion ofthe allyl (meth)acrylate monomer has peaked, but could be added at any point after polyllleli~ation has started. The other components, such as the initiator, stabilizers (if used), surfactants and modifiers are present in the reaction rnixture as described in the processing steps herein above.
Following polymerization, a stable aqueous suspension of rnicrospheres at room tel.l?t;la~re is obtained. The suspension may have non-volatile solids contents of from about 10 to about 70 percent by weight. Upon prolonged st~n~3ing, the suspension typically separates into two phases, one phase being an aqueous, esstonti~lly polymer miclo~hcre-free phase and the other phase being an aqueous suspension ofthe polymeric microspheres, that is, the rnicrosphere-rich phase. The aqueous CA 0224l~33 l998-06-24 W O 97/26286 PCT~US96/18522 suspension of rnicrospheres may be utilized immediately following polyl"w,2alion~
because the suspension of microsphel es of the present invention is particularly stable to agglomeration or coae~ tiQn Adv~nt~geously, the microspheres of the present invention can be easily coated from an aqueous solution. Surprisingly, the 5 microspheres of the present invention are well suited for conventional coating techn;~ue~ and have e-~h~ ~ced fluid processine characteristics.
The micro~he,e-rich phase can be diluted with an additional amount of water or solvent, or redispersed upon shaking or other means of agitation. Generally, this aqueous s..~pçn~ion can be coated onto a backing or other substrate being employed 10 using conventional coating methods, such as slot die coating, to provide an adhesive coating. The microspheres can be compounded with various rheology modifiers and/or latex adhesives or "binders". Typically, the adhesive coating which, when dried, exhibits a dry coating weight in the range of 0.2 to about 2 grams per square foot to provide an adhesive-coated sheet material in which the adhesive coating comprises 15 polyrneric microspheres, polymeric stabilizer, surfactant, and optionally rheology modifiers, and/or latex adhesives. Alternatively, the microspheres may be isolated and combined with an organic solvent if desired prior to coating them onto the backing.
Properties of the pressure-sensitive adhesives of the present invention can be altered by the addition of a tackifying resin(s) and/or pl~ti~i7er(s) after the 20 polyrnerization. Plert:l.ed tackifiers and/or pl~stici7ers for use herein include hydrogçn~ted rosin esters commercially available from such companies as Hercules, Inc. under the trade names of ForalrM, Regalrez~) and PentalynTM. Tackifying resins also include those based on t-butyl styrene. Useful plasticizers include but are not limited to dioctyl phthql~te, 2-ethylhexyl phosphate, tricresyl phosphate and the like. If 25 such tackifiers and/or pl~stiri7ers are used, the amounts used in the adhesive mixture are amounts effective for the known uses of such additives.
Optionally, adjuvants, such as, rheology modifiers, colorants, fillers, stabilizers, pressure-sensitive latex binders and various other polymeric additives can be utili7ed If such adjuvants are used, the amounts used in the adhesive mixture are amounts30 effective for the known uses of such adjuvants.
Suitable backing or substrate materials for use in the present invention include, but are not limited to, paper, plastic films, cellulose acetate, ethyl cellulose, woven or nonwoven fabric comp,ised of synthetic or naturai materials, metal, met~lli7ed polymeric film, cerarnic sheet material and the like. Generally the backing or substrate material is about 50 llm to about 155 llm in thir~ness, although thicker and thinner backing or substrate materials are not precJuded Particularly useful articles plq~ared using the microsphere adhesives of the present invention include repositionable adhesive products such as repositionable note and paper products, repositionable tape and tape flags, easel sheets, repositionable glue stick and the like, but may also include other non-repositionable industrial conul.e, ~,;al, and medical adhesive products.
The present invention is further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. All materials are COl~ cially available or known to those skilled in the art unless otherwise stated or apparenl. The following examples are illustrative in nature and are not intended to limit the invention in any way.
Examples Test A~ethods Solvent Soll~ble rol~, - , Contcnt To de~e.""ne the solvent soluble polyrner content of the prepared microspheres the following process is used.
Dry applo~in~alely 1 gram of the water suspension of microspheres in a vacuum oven without heat. A~er drying, add 1 OOml of n-heptane and shake for 24 hours. A~er chskin~ pour through a filter paper (30 rnicron pores) to remove thenon-soluble content. Dry the filtrate in a lOO"F oven.
The weight of the dried filtrate divided by the dried suspension microspheres isthe % solvent soluble polymer content.
Peel A~ P~;On to Bond Paper Peel adhesion is the force required to remove a coated sheet from a bond paper substrate at a specific angle and rate of removal. In the examples this force ise,.~ ssed in grams per one inch width of coated sheet. The procedure followed is:
CA 02241~33 1998-06-24 A strip, one inch wide, of coated sheet is applied to the ho"zonlal surface of 20 pound bond paper. A 4.5 Ib. hard rubber roller is used to firmly apply the strip to the bond paper. The free end of the coated sheet is ~tta~-ed to the adhesion tester load cell such that the angle of removal will be 90 degrees. The test plate is then clal,lped in 5 the jaws of the tensile testing m~hine which is capable of moving the plate away from the load cell at a consla"l rate of 12 inches per minute. A load cell reading in grams per inch of coated sheet is recorded. The sa-,.l,les are tested three times. The average value of the three tests is reported.
Peel,4~ L.. to Fabnc The sample to be tested is prepared by applying a one inch wide coated sheet to fabric found on StePlc~se office panels using a 4.5 Ib. hard rubber roller. The applied sample is stored for 24 hours at 50% RH and 70~F conditions before the tensile test is commenced. The tensile test is carried out as described above and the average value of three tests is reported in grams per inch of coated sheet. The aged adhesion to 15 fabric is pe~ro""cd as above a~er the applied sample is aged on the fabric for 3 days at 80% relative humidity and 70~F conditions.
Peel~ hes;o,.toPaintedSheebock The sample to be tested is prepared by applying a one inch wide coated sheet to a painted sheetrock substrate using a 4.~ Ib. hard rubber roller. The painted sheetrock 20 test substrates are p,t;pa- ~;d by applying a coating of a standard sernigloss latex enamel paint to the sheetrock. The applied sample is stored for 24 hours at 50% RH and 70~F
conditions before the tensile test is co....- ,nced The tensile test is carried out as described above and the average value of three tests is reported in grams per inch of coated sheet. The aged adhesion to painted sheetrock is ,o~lro"l~ed as above after the 2~ applied sample is aged on the sheet rock for 3 days at 70% relative humidity and 70~F
conditions.
A~icrosphere ~ransfer Microsphere transfer for the purposes of this test is defined as the amount of micl os~,heles that ll ar.s~er to an applied paper when the coated sample is removed 30 from the paper. ~t is measured as the percent ofthe area covered with microspheres.
The procedure followed is:
CA 0224l533 l998-06-24 W O 9~126286 16 PCT~US96/18522 A three-quarter (3/4") (1.9 cm) wide strip of microsphere coated sample is adhered to a clean area of a clay coated paper co",.l.. rcially available as Kromcoat, for a few seconds using the mechanical rolling action provided by an TLMI release and adhesion tester and then is removed at a 90~ degree angle at a con~ l rate. The clay 5 coated strip is then surveyed by an image processor through a video camera and the percent microsphere coverage of the viewed area is recorded. Ten fields were surveyed on each test sample and the average of these readings is recorded.
Glossary AA - acrylic acid 10 ACM - acrylamide CRA - crotonic acid FA - fumaric acid HEMA- hydlo~yethyl methacrylate IOA - isooctyl acrylate 15 IPA- isopropyl alcohol ITA - itaconic acid NVP - N-vinyl pyrrolidone PSR - painted sheetrock F - fabric 20 RH - relative humidity Example I
To a two liter three necked flask equipped with a thermometer meçh~nical stirrer and nitrogen inlet tube was charged 597.5 gm of deionized water 35 gm of a 10% solids solution of Stepanol AMV (trade name for a 28% solids solution of 25 al~",.o-- lmlaurylsulfateCO~ clciallyavailablefromStepanCompany) 17.5gmofa 10% solution of Goodrite K702 (trade name for a 25% solids solution of polyacrylic acid, 240,000 weight average molecular weight co"l",eicially available from B.F.Goodrich Company) which had been neutralized to a pH of 7.0 with concentrated ammonium hydroxide. To this solution was added 350 gm of isooctyl acrylate and 1.1 30 gm of Perkadox 16N (trade name for a 95% active bis (4-tert-butylcyclohexyl) peroxydicarbonate initiator co~ e,cially available from AKZO Chemicals Inc.), and 0.14 gm (.04% by weight of the monomer) of dodecanethiol (a chain transfer agentcommercially available from Aldrich Chemical Company). The agitation rate was set at 410 revolutions per minute (RPM) and the reaction mixture was heated to 50~C,3 5 and purged with nitrogen. The stirring, and nitrogen purge was maintained throughout the reaction period. The reaction was initially set at 50~C and exothermed a~er a few minutes and peaked at 76~C. The batch was m~ ed at 50~C for 22 hours, cooled and filtered through a cheese cloth. The particle size was 54 ~m.
This adhesive di~, ~;on was credl.led and the lower phase removed. The 5 clea."ed adhesive was made into a 50% solids coating by adding 9% Hycar 2600 x 222 (trade name for an aaylate terpolymer latex co.~ ;n;l-g an N-alkyl substituted ac~ylamide available from B.F. Goodrich Com~ r) and 1% acrysol ASE60 (trade name for a 28% solids acid containing aclylic emulsion copolymer rheology modifier available from Rohm and Haas Company). The adhesive coating mixture was 10 neutralized with ammonia and applied to a primed bond paper using coating procedures known to the art. The test results are su".,..ar.~ed in the Tables 1 and 2 below.
Exam~le 2 - 6 The examples were prepared according to the procedure described in Example 15 1 except that the amount of dode~nethiol was changed and the amount and type of commonomer was changed. The formulations and test results are sl-mm~rized in Tables 1 and 2 below.
Table 1 %Solvent E~ample Comonomer % DD d e - ~IParticle Soluble Sue (~lm) Portion None 0.04 54 57 2 1%Hydroxy 0.04 53 71 E~yl Me~acrylate 3 1% Acrylic 0.03 43 83 Acid 4 0.5% Acrylic 0.03 34 92 Acid 1% N Vinyl 0.02 42 65 Pyrrolidone 6 1% 0.03 35 80 Acrylamide W O 97/26286 PCT~US96/18522 Table 2 E~mple Adhaion Adhesion Adbesion Aged Agcd Total To Bond To l'SR To F Adb~s:~n Adhesion Transfer Paper PSR F
59.9 16.7 2.9- 21.3 14.2 4.3 2 98.6 21.7 3.5 28.4 3.6 1.2 3 109.7 42.4 6.0 52.3 8.0 1.0 4 89.9 21.5 2.3 ~1.4 2.7 0.4 92.1 18.9 1.6 38.2 1.9 2.8 6 69.9 18.7 1.4 32.2 2.0 0.6 Com~ar~hve Examples Cl-C3 These examples were prepa- ed according to the procedure described in 5 Example 1 except the dodec~nethiol was not added and the reaction temperature was ed for only 5 hours to prevent excessive cro~linkin~ Comparative example C-l was actually made according to the U.S. Patent No. 4,166,152 process and yielded a microsphere dispersion which had 8% coa~ m The formulations of the compd~d~ e examples are su.~ ,a-iGed below in Table 3 and the test results in Table 4.
0 Comp~~h 1~ Example - C4 A microsphere dispersion was made according to IJ.S. Patent No. 3,691,140 using 2.5% ammonium acrylate and 97.~% isooctyl-acrylate. This process yielded microspheres that were 40 microns in size and 20% solvent soluble portion. The adhesive dispersion was creamed and the lower phase removed. The creamed adhesive 1~ was made into a 50% solids coating by adding 20% Hycar 2600X222 (trade name for an acrylate terpolymer latex co~ ;nin~e an N-Alkyl substituted acrylamide available from B. F. Goodrich Company), and 1 % Acrysol ASE60 (trade name for a 28% solidsacid co.~in;ng acrylic emulsion copolymer thickener available from Rohm and HaasColllp~ly). This coating was applied to a primed bond paper using coating procedures 20 known to the art. The formulation ofthis coll,palali~e example is summarized in Table 3 below and the test results are summarized in Table 4 below.
R~kground of the Invention Repositionable adhesives are comrnonly used for temporary messaging or signage in the home and office environment. This type of product is typified by Post-it@) brand notes. When using such a product it is desired that the note adhere to a 10 variety of surfaces yet be cleanly removable from the surface without leaving adhesive residue, while m~int~ining the repositionable characteristics of the notes.
References can be cited for the prepal ~lion and/or use of inherently tacky, polymeric microsphere adhesives (~efor example, U. S. Patent Nos. 3,691,140 and 4,166,152). Such rnicrosphere adhesives are typically used for the commonly 15 recognized repositionable notes.
Various investigators have sought to improve or further enh~nce adhesion to surfaces other than the comrnonly used paper surfaces. Various techniques have been used, such as chemical modification of the microsphere, alteration of the adhesive composition, inrln-ling the use of binders and the like, or process modifications. For 20 example, U.S. Patent No. 5,053,436 describes a hollow microsphere, wherein the rnicrosphere provides increased re~ nce to adhesive transfer and an increased adhesion level. Along the same line, U.S. Patent No. 4,988,567 describes microspheres having multiple small voids.
In yet another attempt, U.S. Patent No. 5,326,842 describes a dual 25 polymerization process wherein high-tack adhesives are produced wherein a chain ll ~nsrer agent is used in the first step (suspension polymerization) and the second step (çtn~ ion polymerization) provides stability of the final material.
However, to date, control of the solvent soluble portion of the microsphere to produce a stable repositionable rnicrosphere adhesive with enhanced adhesion has not 30 been contemplated.
CA 02241~33 1998-06-24 WO 97126286 PCT~US96118522 Summary of the Invention Briefly, in one aspect of the present invention, a microsphere adhesive composition is provided comprising a 30-98% solvent soluble portion.
In particular, the present invention comprises a microsphere adhesive 5 composition co".~"is.l~g:
(a) a plurality of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of react~ntc comprising polymerizable starting materials comprising at least one C4-Cl4 alkyl (meth)acrylate monomer and optionally at least one comonomer, (b) optionally, a polymeric st~9bili~r in an amount of beLween about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres, preferably about 0.1 to about 1.5 parts by weight per 100 parts by weight of the microspheres;
(c) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres, preferably no greater than 3 parts by weight and most pl ~re.ably in the range of 0.5 to about l . 5 parts by weight per 100 parts by weight of the microspheres;
(d) a modifier, wherein the modifier can be at least one of a chain tl ansrer agent, a tackifier, a solvent or the like in an amount that is sufficient to provide microspheres with a solvent soluble portion in the range of 30-98%, preferably in the range of 40-95%; and (e) an initiator present in amounts ranging from 0.1 to applu~hl,ately 2 parts by weight per 100 parts by weight of the polymerizable monomer starting material.
As used in this application, the notation "(meth)acrylate" refers to acrylate and methacrylate.
A modifier may be used to regulate the solvent soluble portion of the microspheres and it is added to the polymerization mixture in an amount sufficient to provide a solvent soluble portion that is in the range of 30-98%, preferably in the range of 40-95%. Various modifiers may be used within the scope of this invention and the amounts used are those that sufficiently provide the microspheres ~,vith a solvent soluble portion. Such amounts would range, for example for solvents from 1-30%, for tackifiers from 1-30% and for chain transfer agents, up to about 0.15%
CA 02241~33 1998-06-24 W O 97126286 PCT~US96/18522 Particularly useful modifiers are chain transfer agents. To control the molecular weight of the polymer being formed in the microsphere a chain transferagent or modifier is used. Many halogen-and sulfur-co~ organic compounds function well as chain 1. arl~rer agents in free radical polymerizations. Non-limiting 5 examples of such agents are: carbon tetlabl~),lude, carbon tetrachloride, dodec~n~lhiol, iso-octylthioglycolate, butyl mercaptal1, and tertiary-dodecyl ealJIan. Particularly useful chain ~l~nsrel agents are long chain meJ.~I~t~ns, such as clodec~neth;cl. The amount of chain l.~r~, agent suitable for microsphere polymerizations is calculated on a weight basis to the entire polymerizable content.
10 The chain l~ rer agent is prefe.ubly added at up to about 0.15%, more p-efe.ably up to about 0.12% and most preferably up to about 0.08%. These levels are adequate to provide a solvent soluble polymer component in the microsphere of up to about 98%.
Other useful modifiers are solvents. Examples of which are but not lin~ited to aliphatic or aromatic solvents such as heptane, ben_ene, toluene and the like; alcohols 15 such as methanol, isopropyl alcohol, and the like; and ketones such as acetone, methyl ethyl ketone and the like. The amount of solvent suitable for microsphere poly..lc-i~a~ions is calcul~ted on a weight basis to the entire polymerizable content.
The solvent is prt;Çelàbly added at up to about 30%, more preferably up to about 15%
and most prefe.ably up to about 5%. These levels are adequ~te to provide a solvent soluble polymer component in the microspheres of up to about 98%.
Still other useful modifiers include t~c~ifiers and/or plasticizers. Examples ofwhich are but not limited to: hydrogenated rosin esters commercially available from such companies as Hercules, Inc. under the tradçnqmes of ForalTM, Regalrez~ and PentalynTM. Tackifying resins also include those based on t-butyl styrene. Useful pl~tici7Prs include but are not limited to dioctylphth~l~tel 2 ethylhexyl phosphate, tricresyl phosphate, mineral oil and the like. The tackifier and/or p!~ctici7er are preferably added at up to about 30%, more preferably up to about 15% and most preferably up to about 5%. These levels provide a solvent soluble polymer component in the microsphere of up to about 98%.
In another aspect of the present invention a one step suspension polyrnerizationprocess is provided for preparing polymeric elastomeric m~crospheres comprising the steps of:
CA 02241~33 1998-06-24 (a) stirring or a~it~tine a mixture comprising polymerizable monomer starting materials comprising:
(i) at least one C4-C14 alkyl (meth)acrylate monomer and, optionally at least one comono.,~., (ii) an initiator for the polymerizable monomer starting materials present in amounts ranging from 0.1 to approxin~àlely 2 parts per weight per 100 parts by weight of the poly.".,- .~able monomer starting materials;
(iii) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monon, starting materials;
(iv) a surfactant in an amount no greater than about S parts by weight per 100 parts by weight of polymerizable monomer, preferably no greater than about 3 parts by weight and most prefe.l.bly in the range of 0.5 to 1 5 parts by weight; (v) water to form an oil in water suspension; and (vi) a modifier in an amount sufficient to provide a solvent soluble portion in the range of 30-98%; and (b) polymerizing the (meth)acrylate monulll~l(s) and the comonomer(s), if pr~se..l, wl.e~ cill microspheres are provided.
In yet another aspect, the present invention provides a two-step suspension 20 polymerization process for pl epar;i g polymeric elastomeric microspheres from polymerizable monomer stating materials, wherein the process comprising the steps of (a) stirring or ~it~tin~ a mixture compli~;.-g:
(i) at least one C4-C14 alkyl (meth)acrylate monomer;
(ii) an initiator for the monomer present in amounts ranging from 0 1 to 25 approx;~ely 2 parts per weight per 100 parts by weight ofthe polyllleli~able monomer starting materials;
(iii) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iv) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight ofthe polymerizable monomer starting materials, CA 02241~33 1998-06-24 W O 97126286 PCT~US96/18S22 preferably no greater than 3 parts by weight and most preferably in the range of 0. 5 to 2 parts by weight;
(v) a modifier in an amount sufficient to provide a solvent soluble portion in the range of 30-98%; and (vi) water to form an oil in water suspension;
(b) at least partially polymerizing the polyl.,e,i~able monomer starting materials;
(c) adding to the suspension at least one comonomer; and (d) contin~ing the polyrnerization of the polymerizable monomer starting materials; wherein microspheres are provided.
The present invention also provides in another aspect a sheet material comprising a backing and a coating of repositionable pressure sensitive adhesivedescribed above is coated on at least one portion of at least one major surface.Advantageously, the present invention provides a rnicrosphere-based pressure sensitive adhesive having a high solvent soluble fraction that adheres to rough surfaces such as fabric, removes cleanly, and exhibits the ability to be reapplied multiple times if desired. Even with this ~nh~nced adhesion to rough surfaces the microsphere adhesive will still adhere non-destructively to fragile surfaces such as paper. Furthermore, the microsphere adhesive of this invention is prepd-ed according to resource efficient methods.
Several features of the adhesive of the present invention provide a number of desirable advantages that have heretofore been unavailable. ~or example several advantages include, (a) improved adhesion to various surfaces (textured surfaces, fabric, wood, painted surfaces, glass, vinyl, etc), (b) high adhesion without fiber pick or substrate damage on removal from substrates, (c) adhesive strength that remains col~slal~l or slightly builds after a period of time, and (d) a microsphere adhesive that adheres to a substrate or b~c~ing and easily removes from applied surfaces without llallsrwling or leaving an adhesive residue on the applied surface.
Description of the Preferred Embodiment(s) The microspheres obtained in the present invention are the reaction product of (a) at least one alkyl (meth)acrylate ester wherein the alkyl group conlaills four to about 14 carbon atoms, p.ef~-ably four to about 10 carbon atoms and, optionally, a CA 02241~33 1998-06-24 W O 97/26286 PCTAUS96tl8522 comonomer. The comonomer, if present may be nonpolar, ionic polar or rnixtures of such monomers.
Useful alkyl (meth)acrylate mon~ are those monofunctional unsaturated (meth)acrylate esters, the alkyl groups of which have from 4 to 14 carbons atoms.
5 Such (meth)acrylates are oleophilic, water d.spel~iblc, and are ess~nti~lly water insoluble. Furthel~..ole, useful (meth)acrylates are those that as homopolyrners, generally have a glass transition te--",c~ ature below about -20~C, or if a combination of monomers is used, such a combination would produce a copolymer or terpolymer generally having a glass trprlcitifm tclup~al~re below about -20~C. Nonlimiting 10 examples of such (meth)acrylates in~l...ie~ but are not limited to, isooctyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isodecyl methacrylate, t-butyl acrylate, t-butyl methacrylate, isobornyl acrylate, methylmeth~crylate, isononyl acrylate, isodecyl acrylate and the like, and the co...binalion thereo~
Preferred alkyl (meth)acrylate monomers include isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, sec-butyl acrylate and mixtures thereof.
Vinyl ester monomers suitable for use in the present invention include but are not limited to: vinyl 2-ethylheY~oate, vinyl caprate, vinyl laurate, vinyl pelargonate, vinyl hexanoate, vinyl propionate, vinyl dec~noate, vinyl act~noate, and other monofunctional unsaturated vinyl esters of linear or branched carboxylic acids co~ g l to 14 carbon atoms, which as homopolymers have glass transition temperatures below about -10~C. ~lerel-~d vinyl ester monomers include vinyl laurate, vinyl caprate, vinyl 2-ethylh~ no~le, and mixtures thereof.
Additional other vinyl monomers which, as homopolymers, have glass transition telll?c~al~lres higher than about -10~C to 0~C, such as vinyl acetate, acrylonitrile, llu~Lures thereof and the like, may optionally be utilized in conjunction with one or more of the acrylate, meth~crylate and vinyl ester monomers provided the glass transition temperature ofthe res~llt~nt polymer is below about -10~C.
Suitable comonomers include nonpolar, ionic, polar monomers and mixtures thereof. In addition to using one or more acrylate monomers as a comonomer, as described above, the following are non-limiting examples of comonomers:
W 097/26286 PCTrUS96/18522 (A) ionic comonomers, such as sodium meth~crylate, ammonium acrylate, sodium acrylate, (I) l~i",~Lhylamine p-vinyl b~ rle, (II) 4,4, 9-trimethyl-4-azonia-7-oxo-8-oxa-dec-9-ene-1-sulphonate, (III) N,N-dimethyl-N-(,B-mPth~crylo~y~thyl) ammonium propionate betaine, (IV) l~ hylamine met~ rylimide, (V) 1, l -dimethyl-5 1(2,3-dihydroxypropyl)amine meth~ ,fylimide; any zwitterionic monomer and the like;
~ B) non-polar comonomers include but are not lirnited to, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, isodecyl mP.th~~rylate, t-butyl acrylate, t-butyl meth~rrylate, isobornyl acrylate, octyl acrylamide, metl"~ rylate, isononyl acrylate, isodecyl acrylate, styrene and the 10 like, and the co",bil,alion thereo~
(C) Polar comonomers may or may not contain a dissociable hydrogen.
Examples of suitable polar comonomers include organic carboxylic acids Col~ JIiSillg 3 to about 12 carbon atoms and having generally 1 to about 4 carboxylic acid moieties.
Nonl;,~ e examples of such monomers acrylic acid, methacrylic acid, itaconic acid, 15 fumaric acid, crotonic acid, maleic acid, ~-carboxyethylacrylate and the like. In addition suitable polar comonomers include acrylamide, methacrylamide, 2-h~dro~yelllyl acrylate, and the like.
In addition, one class of suitable comonomers are amino-functional monomers having a nucleus or portion ofthe nucleus ofthe general formula (a):
o CH2=CHRl--C--L--R2--(NR3R4)X
(1) wherein R, is--H,--CH3,--CH2CH3, cyano or carboxymethyl;
R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms;
R3 and R4 are independently H or an alkyl group containing 1 to about 12 carbon atoms or an arylalkyl group or together fonn a cyclic or heterocyclic moiety;
L is carbon-carbon bond, O, NH or S; and x is an integer of 1 to 3.
Nonlimitin~ examples of comonomers according to formula (1) include N, N-dimethyl-aminoethyl(methyl)acrylate, N,N-dimethylaminopropyl-(meth)acrylate, t-butylaminoethyl(methyl)acrylate and N,N-diethylaminoacrylate.
W O 97/26286 PCTrUS96/18522 Another class of suitable comonomers are comonomers having a nucleus or portion of the nucleus of the general formula (2):
o CH2=CHRl--C--L--R2(R~
(2) wherein R, is H,--CH3,--CH2CH3, cyano or carboxymethyl;
R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms;
R5 is -O-, alkylene oxide coJnp~ g 1 to 5 carbon atoms, or phenoxy oxide, wherein the alkylene oxide would in~lude~ -CH20-, -CH2CH20-, -CH2(CE~)CH30-, and the like;
R6 is H, -C6H4OH, or -CH3 L is a carbon-carbon bond, O, NH or S; and x is an integer with the proviso that when R5 is -O-, x is an integer of 1-3.
Nonlimitin~ examples of comonomers according to formula (2) inc}ude Lydloxye~llyl (meth)acrylate, glycerol mono(meth)acrylate and 4-hydroxybutyl (meth)acrylate, acrylate termi~l~ted pol(ethylene oxide), mçth~crylate termin~ted poly(ethylene oxide); methoxy poly(ethylene oxide) meth~crylate; butoxy poly(ethylene oxide) m~th~crylate; acrylate termin~ted poly(ethylene glycol); methacrylate termin~ted poly(ethylene glycol); methoxy poly(ethylene glycol) methacrylate; butoxy poly(ethylene glycol) mPt~erylate and mixtures thereof.
Yet another class of suitable comonomers are amido-functional monomers having a nucleus or portion of the nucleus of the general formula (3):
o CH2=CHRI--C--NR3R4 (3) wherein R~ is H,--CH3, -CH2CH3, cyano or carboxymethyl; and R3 R4 are independently H or an alkyl group cont~ining 1 to about 12 carbons or an arylalkyl group or together form a cyclic or heterocyclic moiety.
Nonlimiting examples of comonomers according to formula (3) include N-vinyl 30 pyrrolidone, N-vinyl caprolactom acrylamide or N, N-dimethyl acrylamide.
W O 97/26286 PCTrUS96/18522 Nonlimiting examples of other suitable comonomers that do not fall within the above classes but are within the scope of permissible comononers include (meth)acrylonitrile, furfuryl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate, 2-vinyl pyridine, and 4-vinyl pyridine.
Typically, when a co,nonor"er is present, the relative amounts by weight of the alkyl (meth)acrylate monomer(s) and the comonomer is in the range of about 99.5/0.5 to 75/25, and preferably is in the range of 9812 to 92/8.
A modifier may be used to regulate the solvent soluble portion of the microspheres and it is added to the polyll,e.i~lion mixture in an amount sufficient to provide a solvent soluble portion that is in the range of 30-98%, preferably in the range of 40-95%. Various modifiers may be used within the scope of this invention and the amounts used are those that sufflciently provide the microspheres with a solventsoluble portion. Such amounts would range, for example for solvents from 5-30%, for tackifiers and/or pl~sti~i7ers from 1-30% and for chain transfer agents, up to about 0.15%.
Particularly useful modifiers are chain tran~r~l agents. To control the molecular weight of the polymer being formed in the microsphere it is desirable to use a chain transfer aBent or modifier. Many halogen-and sulfur-co.~ in~. organic compounds function well as chain l, ans~.- agents in free radical polymerizations Non-limiting examples of such agents are: carbon tell~bro-,lide, carbon tetrachloride, dodec~nethiol, iso-octylthioglycolate, butyl ,.,~-,aptan, and tertiary-dodecyl mel~a~tan. In this invention it is efficacious to employ long chain merca~lans such as dodec~net~iol. The amount of chain l-~ns~r agent suitable for these microsphere polymerizations is c~lc~ ted on a weight basis to the entire polymerizable content.
The chain transfer agent is ple~-~bly added at up to about 0.15% more preferably up to about 0.12% and most preferably up to about 0.08%. These levels are fldeq-l~te to provide a soluble polymer content in the microsphere of up to about 98%.
The microsphere adhesive composition may also contain a cro~.clin~ing agent.
Examples of useful crosslin~ing agents include, but are not limited to: mllltifilnctiona (meth)acrylate(s), e.g., butanediol diacrylate or hexanediol diacrylate or othermllltifilnctional crosslinkers such as divinylbenzene and mixtures thereof When used, crosslinker(s) is (are) added at a level of up to about 0.15 equivalent weight percent, W O 97126286 PCT~US96/18S22 preferably up to about 0.1 equivalent weight percent, of the total polymerizablecomposition with the proviso that the con~billalion of crosslin~in~ agent and modifier concentrations are chosen to obtain a microsphere with 30 to 98% solvent solubleportion.
The llhcrosp}ul es of the present invention are prepared by suspension poly."c.i a~ion using either a one-step or two-step process as described in detail below. Suspension polymerization is a procedure wherein a monomer is dispe. ~ed in a medillm (usually a~ueous) in which it is insoluble. The polymerization is allowed to proceed within the individual polymer dl~Fletc Monomer soluble free-radical 10 initiators are preferably used. The kinetics and the ecl.~ are those for the co~ ondi.l~ bulk polylll~l ;zalion under similar conditions of tel.lperhlllre and initiator conc~i"~ ion.
Initiators affecting polymerization are those that are norrnally suitable for free-radical pol~lne~ ion of acrylate monomers. Examples of such initiators include thermally-activated initiators such as azo compounds, hydroperoxides, peroxides and the like and photoinitiators such as benzophenone, benzoin ethyl ether and 2,2-~imethoxy-2 pheny3 acetophenone. Other suitable initiators include lauroyl peroxide and bis(t-butyl cyclohexyl)peroxy ~;call~ollale The initiator is present in a catalytically effective amount s.-fficient to bring about high monomer conversion in a predetermined time span and ttlllp~l alure range. Typically, the initiator is present in amounts ranging from 0.1 to appro~ul.lately 2 parts per weight per 100 parts by weight of the polyrnerizable monomer starting materials.
Parameters that affect the concenll alion of initiator employed include the typeof initiator and particular monomer and/or monomers involved. It is believed that catalytically effiective conce,llldlions range from about 0.1 to about 2 percent by weight ofthe total monomers and more preferably, from about 0.20 to about 0.70 percent by weight monomers and/or monomers.
Optionally, a polymeric stabilizer may be used. Advantageously, the presence of the stabilizer perrnits the use of relatively low amounts of surfactant while still obtaining microspheres.
Any polymeric stabilizer that effectively provides sufficient stabilization of the final polymerized droplets and prevents agglomeration within a suspension CA 02241~33 1998-06-24 W 097/26286 11 PCT~US96118522 polymerization process is useful in the present invention. When used, a polymeric stabilizer will typically be present in the reaction rnixture in an amount by weight of about 0.1 to about 3 parts by weight per 100 parts of polymerizable monomer, andmore plerel~bly will be present in an amount by weight of about 0.1 to about 1.5 parts S by weight per 100 parts of polyrnerizable monomer.
Fxenlpl~ry polymeric ~ ~L 'li7çrs indude salts of polyacrylic acids of greater than 5000 m~lecul~r weight average (for eY~rnrle, ammonium, sodium, lithium and potassium salts), carboxy modified polyacrylamides (for example, Cydn~..ne.TMA-370 from American Cyanamid), copolymers of acrylic acid and dimethylaminoethylmethacrylate and the like, polymeric quaternary amines (for example, General Analine and Film's GafquatlM 755, a quaternized polyvinyl-pyrollidone copolymer, or Union Carbide's "JR-4007', a quaternized amine substituted cellulosic), cellulosics, and carboxy-modified cellulosics (for example, Hercules' NatrosollM CMC Type 7L, sodium carboxy methycellulose).
Surf~ct~ntc will typically be present in the reaction mixture in an amount of nogreater than about 5 parts by weight per 100 parts by weight of polymerizable monomer, p[~f~l ably no greater than about 3 parts by weight, and most preferably in the range of 0. S to 1.5 parts by weight per 100 parts by weight of polymerizable monomer.
Useful surf~ct~ntc include anionic, cationic, nonionic or amphoteric surfactantsand include but are not lirnited to anionic surfr~t~nts, such as alkyl aryl sulfonates, for example sodium dodecylbenzene sulfonate and sodium decylbenzene, sodium and ammonium salts of alkyl sl.lf~tes, for examples sodium lauryl sulfate, and ammonium lauryl sulfate; nonionic surf~Lct~ntc, such as ethoxylated oleoyl alcohol and polyoxyethylene octylphenyl ether; and cationic surf~.t~ntc, such as a mixture of alkyl dimethylbenzyl ammonium chlorides wherein the alkyl chain contains from 10 to 18carbon atoms. Amphoteric surf- - t~nt.c are also useful in the present invention and include for example sulfobetaines, N-alkylaminopropionic acids, and N-alkybetaines.
To initiate the pOI~ ,. ;~lion reaGtion, a sufficient number of free radicals must be present. This may be achieved through severat means that are well known in the art, such as heat or radiation free-radical initiation. For example, heat or radiation can be applied to initiate the pol~,l,el izalion of the monomers, which is an exothermic CA 02241~33 1998-06-24 W O 97126286 PCTrUS96/18522 reaction. However, it is pl erel I ed to apply heat until thermal decomposition of the initiators gene,ales a s~fficient number offree radicals to begin the reaction. The tc~ )elal~lre at which this occurs varies greatly depen~ling upon the initiator used.
In addition, deoxyEçn~tion of the polymerization reaction mixture is often desirable. It is well known that oxygen dissolved in the reaction n~iAlule can inhibit polymerization and it is de~l ble to expel this dissolved oxygen. ~Ithoueh~ an inert gas bubbled into the reaction vessel or through the reaction mixture is an effective means of deo~ygel-alion, other techniques for deox~ n~l ;on that are conl~alil~le with suspension polymerization can be used. Typically, nitrogen is used to deo~ygenate, although any of the Group VIIIA (CAS version) inert gases are also suitable.
While specific time and stirring speed parameters are dependent upon monomers, and initiators, it is desirable to pl edis~,el ~e the reaction mixture until the reaction mixture reaches a state where the average monomer droplet size is between about 1 l~m and 300 llm and preferably between 20 llm and 70 ~m. The average particle size tends to decrease with increased and prolonged agitation of the reaction mixture.
~ererably, stirring and nitrogen purge are m~int~ined throughout the reaction period. Initiation is begun by heating the reaction mixture. Following polymerization, the reaction mixture is cooled.
In a one-step process both the alkyl (meth)acrylate monomer and any optional comonomer are present together in the suspension at the initiation of polymerization.
In a two-step process any optional comonomer is typically added after the initial exotherm resulting from polylll~liza~ion ofthe allyl (meth)acrylate monomer has peaked, but could be added at any point after polyllleli~ation has started. The other components, such as the initiator, stabilizers (if used), surfactants and modifiers are present in the reaction rnixture as described in the processing steps herein above.
Following polymerization, a stable aqueous suspension of rnicrospheres at room tel.l?t;la~re is obtained. The suspension may have non-volatile solids contents of from about 10 to about 70 percent by weight. Upon prolonged st~n~3ing, the suspension typically separates into two phases, one phase being an aqueous, esstonti~lly polymer miclo~hcre-free phase and the other phase being an aqueous suspension ofthe polymeric microspheres, that is, the rnicrosphere-rich phase. The aqueous CA 0224l~33 l998-06-24 W O 97/26286 PCT~US96/18522 suspension of rnicrospheres may be utilized immediately following polyl"w,2alion~
because the suspension of microsphel es of the present invention is particularly stable to agglomeration or coae~ tiQn Adv~nt~geously, the microspheres of the present invention can be easily coated from an aqueous solution. Surprisingly, the 5 microspheres of the present invention are well suited for conventional coating techn;~ue~ and have e-~h~ ~ced fluid processine characteristics.
The micro~he,e-rich phase can be diluted with an additional amount of water or solvent, or redispersed upon shaking or other means of agitation. Generally, this aqueous s..~pçn~ion can be coated onto a backing or other substrate being employed 10 using conventional coating methods, such as slot die coating, to provide an adhesive coating. The microspheres can be compounded with various rheology modifiers and/or latex adhesives or "binders". Typically, the adhesive coating which, when dried, exhibits a dry coating weight in the range of 0.2 to about 2 grams per square foot to provide an adhesive-coated sheet material in which the adhesive coating comprises 15 polyrneric microspheres, polymeric stabilizer, surfactant, and optionally rheology modifiers, and/or latex adhesives. Alternatively, the microspheres may be isolated and combined with an organic solvent if desired prior to coating them onto the backing.
Properties of the pressure-sensitive adhesives of the present invention can be altered by the addition of a tackifying resin(s) and/or pl~ti~i7er(s) after the 20 polyrnerization. Plert:l.ed tackifiers and/or pl~stici7ers for use herein include hydrogçn~ted rosin esters commercially available from such companies as Hercules, Inc. under the trade names of ForalrM, Regalrez~) and PentalynTM. Tackifying resins also include those based on t-butyl styrene. Useful plasticizers include but are not limited to dioctyl phthql~te, 2-ethylhexyl phosphate, tricresyl phosphate and the like. If 25 such tackifiers and/or pl~stiri7ers are used, the amounts used in the adhesive mixture are amounts effective for the known uses of such additives.
Optionally, adjuvants, such as, rheology modifiers, colorants, fillers, stabilizers, pressure-sensitive latex binders and various other polymeric additives can be utili7ed If such adjuvants are used, the amounts used in the adhesive mixture are amounts30 effective for the known uses of such adjuvants.
Suitable backing or substrate materials for use in the present invention include, but are not limited to, paper, plastic films, cellulose acetate, ethyl cellulose, woven or nonwoven fabric comp,ised of synthetic or naturai materials, metal, met~lli7ed polymeric film, cerarnic sheet material and the like. Generally the backing or substrate material is about 50 llm to about 155 llm in thir~ness, although thicker and thinner backing or substrate materials are not precJuded Particularly useful articles plq~ared using the microsphere adhesives of the present invention include repositionable adhesive products such as repositionable note and paper products, repositionable tape and tape flags, easel sheets, repositionable glue stick and the like, but may also include other non-repositionable industrial conul.e, ~,;al, and medical adhesive products.
The present invention is further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. All materials are COl~ cially available or known to those skilled in the art unless otherwise stated or apparenl. The following examples are illustrative in nature and are not intended to limit the invention in any way.
Examples Test A~ethods Solvent Soll~ble rol~, - , Contcnt To de~e.""ne the solvent soluble polyrner content of the prepared microspheres the following process is used.
Dry applo~in~alely 1 gram of the water suspension of microspheres in a vacuum oven without heat. A~er drying, add 1 OOml of n-heptane and shake for 24 hours. A~er chskin~ pour through a filter paper (30 rnicron pores) to remove thenon-soluble content. Dry the filtrate in a lOO"F oven.
The weight of the dried filtrate divided by the dried suspension microspheres isthe % solvent soluble polymer content.
Peel A~ P~;On to Bond Paper Peel adhesion is the force required to remove a coated sheet from a bond paper substrate at a specific angle and rate of removal. In the examples this force ise,.~ ssed in grams per one inch width of coated sheet. The procedure followed is:
CA 02241~33 1998-06-24 A strip, one inch wide, of coated sheet is applied to the ho"zonlal surface of 20 pound bond paper. A 4.5 Ib. hard rubber roller is used to firmly apply the strip to the bond paper. The free end of the coated sheet is ~tta~-ed to the adhesion tester load cell such that the angle of removal will be 90 degrees. The test plate is then clal,lped in 5 the jaws of the tensile testing m~hine which is capable of moving the plate away from the load cell at a consla"l rate of 12 inches per minute. A load cell reading in grams per inch of coated sheet is recorded. The sa-,.l,les are tested three times. The average value of the three tests is reported.
Peel,4~ L.. to Fabnc The sample to be tested is prepared by applying a one inch wide coated sheet to fabric found on StePlc~se office panels using a 4.5 Ib. hard rubber roller. The applied sample is stored for 24 hours at 50% RH and 70~F conditions before the tensile test is commenced. The tensile test is carried out as described above and the average value of three tests is reported in grams per inch of coated sheet. The aged adhesion to 15 fabric is pe~ro""cd as above a~er the applied sample is aged on the fabric for 3 days at 80% relative humidity and 70~F conditions.
Peel~ hes;o,.toPaintedSheebock The sample to be tested is prepared by applying a one inch wide coated sheet to a painted sheetrock substrate using a 4.~ Ib. hard rubber roller. The painted sheetrock 20 test substrates are p,t;pa- ~;d by applying a coating of a standard sernigloss latex enamel paint to the sheetrock. The applied sample is stored for 24 hours at 50% RH and 70~F
conditions before the tensile test is co....- ,nced The tensile test is carried out as described above and the average value of three tests is reported in grams per inch of coated sheet. The aged adhesion to painted sheetrock is ,o~lro"l~ed as above after the 2~ applied sample is aged on the sheet rock for 3 days at 70% relative humidity and 70~F
conditions.
A~icrosphere ~ransfer Microsphere transfer for the purposes of this test is defined as the amount of micl os~,heles that ll ar.s~er to an applied paper when the coated sample is removed 30 from the paper. ~t is measured as the percent ofthe area covered with microspheres.
The procedure followed is:
CA 0224l533 l998-06-24 W O 9~126286 16 PCT~US96/18522 A three-quarter (3/4") (1.9 cm) wide strip of microsphere coated sample is adhered to a clean area of a clay coated paper co",.l.. rcially available as Kromcoat, for a few seconds using the mechanical rolling action provided by an TLMI release and adhesion tester and then is removed at a 90~ degree angle at a con~ l rate. The clay 5 coated strip is then surveyed by an image processor through a video camera and the percent microsphere coverage of the viewed area is recorded. Ten fields were surveyed on each test sample and the average of these readings is recorded.
Glossary AA - acrylic acid 10 ACM - acrylamide CRA - crotonic acid FA - fumaric acid HEMA- hydlo~yethyl methacrylate IOA - isooctyl acrylate 15 IPA- isopropyl alcohol ITA - itaconic acid NVP - N-vinyl pyrrolidone PSR - painted sheetrock F - fabric 20 RH - relative humidity Example I
To a two liter three necked flask equipped with a thermometer meçh~nical stirrer and nitrogen inlet tube was charged 597.5 gm of deionized water 35 gm of a 10% solids solution of Stepanol AMV (trade name for a 28% solids solution of 25 al~",.o-- lmlaurylsulfateCO~ clciallyavailablefromStepanCompany) 17.5gmofa 10% solution of Goodrite K702 (trade name for a 25% solids solution of polyacrylic acid, 240,000 weight average molecular weight co"l",eicially available from B.F.Goodrich Company) which had been neutralized to a pH of 7.0 with concentrated ammonium hydroxide. To this solution was added 350 gm of isooctyl acrylate and 1.1 30 gm of Perkadox 16N (trade name for a 95% active bis (4-tert-butylcyclohexyl) peroxydicarbonate initiator co~ e,cially available from AKZO Chemicals Inc.), and 0.14 gm (.04% by weight of the monomer) of dodecanethiol (a chain transfer agentcommercially available from Aldrich Chemical Company). The agitation rate was set at 410 revolutions per minute (RPM) and the reaction mixture was heated to 50~C,3 5 and purged with nitrogen. The stirring, and nitrogen purge was maintained throughout the reaction period. The reaction was initially set at 50~C and exothermed a~er a few minutes and peaked at 76~C. The batch was m~ ed at 50~C for 22 hours, cooled and filtered through a cheese cloth. The particle size was 54 ~m.
This adhesive di~, ~;on was credl.led and the lower phase removed. The 5 clea."ed adhesive was made into a 50% solids coating by adding 9% Hycar 2600 x 222 (trade name for an aaylate terpolymer latex co.~ ;n;l-g an N-alkyl substituted ac~ylamide available from B.F. Goodrich Com~ r) and 1% acrysol ASE60 (trade name for a 28% solids acid containing aclylic emulsion copolymer rheology modifier available from Rohm and Haas Company). The adhesive coating mixture was 10 neutralized with ammonia and applied to a primed bond paper using coating procedures known to the art. The test results are su".,..ar.~ed in the Tables 1 and 2 below.
Exam~le 2 - 6 The examples were prepared according to the procedure described in Example 15 1 except that the amount of dode~nethiol was changed and the amount and type of commonomer was changed. The formulations and test results are sl-mm~rized in Tables 1 and 2 below.
Table 1 %Solvent E~ample Comonomer % DD d e - ~IParticle Soluble Sue (~lm) Portion None 0.04 54 57 2 1%Hydroxy 0.04 53 71 E~yl Me~acrylate 3 1% Acrylic 0.03 43 83 Acid 4 0.5% Acrylic 0.03 34 92 Acid 1% N Vinyl 0.02 42 65 Pyrrolidone 6 1% 0.03 35 80 Acrylamide W O 97/26286 PCT~US96/18522 Table 2 E~mple Adhaion Adhesion Adbesion Aged Agcd Total To Bond To l'SR To F Adb~s:~n Adhesion Transfer Paper PSR F
59.9 16.7 2.9- 21.3 14.2 4.3 2 98.6 21.7 3.5 28.4 3.6 1.2 3 109.7 42.4 6.0 52.3 8.0 1.0 4 89.9 21.5 2.3 ~1.4 2.7 0.4 92.1 18.9 1.6 38.2 1.9 2.8 6 69.9 18.7 1.4 32.2 2.0 0.6 Com~ar~hve Examples Cl-C3 These examples were prepa- ed according to the procedure described in 5 Example 1 except the dodec~nethiol was not added and the reaction temperature was ed for only 5 hours to prevent excessive cro~linkin~ Comparative example C-l was actually made according to the U.S. Patent No. 4,166,152 process and yielded a microsphere dispersion which had 8% coa~ m The formulations of the compd~d~ e examples are su.~ ,a-iGed below in Table 3 and the test results in Table 4.
0 Comp~~h 1~ Example - C4 A microsphere dispersion was made according to IJ.S. Patent No. 3,691,140 using 2.5% ammonium acrylate and 97.~% isooctyl-acrylate. This process yielded microspheres that were 40 microns in size and 20% solvent soluble portion. The adhesive dispersion was creamed and the lower phase removed. The creamed adhesive 1~ was made into a 50% solids coating by adding 20% Hycar 2600X222 (trade name for an acrylate terpolymer latex co~ ;nin~e an N-Alkyl substituted acrylamide available from B. F. Goodrich Company), and 1 % Acrysol ASE60 (trade name for a 28% solidsacid co.~in;ng acrylic emulsion copolymer thickener available from Rohm and HaasColllp~ly). This coating was applied to a primed bond paper using coating procedures 20 known to the art. The formulation ofthis coll,palali~e example is summarized in Table 3 below and the test results are summarized in Table 4 below.
Table 3 %Sol~vent F. . ~ C~ Particle S~luble Portion S~e C-l None72 10 C-2 1% IIy~o~ 55 18 E~yl M~ la~
C-31% Acrylic 42 14 Acid C-4 2.5%~nH~ 40 20 Acrylate Table 4 Example A-~l eHDn Ad~ Dr Adhesion Aged Aged Total To Bond ToPSR To F Adhesion Adhesion Transfer Paper PSR F
C-l 49.8 8.1 0.1 1.6 0 26.9 C-2 61.3 14.1 0.2 8.3 0 16.1 C-3 62.5 24.2 0.3 7.3 0 4.8 C-4 71.5 22.7 0.5 8.7 0 23.4 The results in Tables 1 and 2 show that the s~mples of this invention with a lowconcentration of a chain transfer agent result in rnicrospheres which are 30 to 95%
solvent soluble and on coating make a repositionable adhesive note with improvedadhesion to painted sheet rock and fine fabric which do not decrease but improved on aging. Thus making a better repositionable adhesive.
The results with the co~ ali~e examples made without any chain transfer agent result in micros,vhc,es that have a 10-20% solvent soluble portion and on coating make a repositionable adhesive note with poor adhesion to painted sheetrock and fine fabric. The adhesion to these surfaces decreased on aging and will usually fall off of vertical surfaces.
Examples 7-8 and Comparat~ve Example CS
One gram of sodium dodecyl benzene sulfonate was dissolved in 360 grams of water. 16.8 grams of poly(ethylene oxide),6 acrylate, 7.2 grams of acrylic acid, a tnc~ifiçr (ECR-180 from Exxon Chemical) in the pelc~ es su...~ ed in Table 5, and 1.05 grarns of Lucidol-75 (75% benzoyl peroxide from Elf Atochem) were 20 dissolved in 216 grams of isooctyl acrylate. The above mixture was ~m~ ified in a WO 97126286 PCTfUS96118522 Gaulin homogenizer, such that the monomer droplet size was 1 llm or less. This emulsion was then ch&.ged to a l liter reactor, stirred at 400 rpm and heated to 65~C
for 4 hours. The r~Culti~ particle size was appru~n~ately S lum as viewed with an optical micl oscope. The % solvent soluble portion of the microspheres are S s-lmm~rized in Table 5.
Table 5 Example Wt. % TJckifier % Solvent Soluble Portion Example To a two liter, three-necked flask equipped with a thermometer, mer1l~ni lO stirrer and nitrogen inlet tube was charged 158 grams of a 0.7% solids solution of Standapol A (trade for a 28% solids solution of ammonium lauryl sulfate commercially available from Henkel Corporation), 158 grams of 1.6% solution of acrylic acid in deionized water, and enough concentrated ammonium hydroxide to neutralize the solution to pH 7. To this solution was added a solution comprised of 100 grams of 15 isooctyl acrylate, 5 grams of heptane and 0.488 grams of Lucidol 70 (trade name for a 70% active benzoyl peroxide initiator co..,...e.eially available from Pennwalt Corporation). The agitation rate was set to 400 rpm. The reaction mixture was heated to 65~C, purged with l~tl~)gen and reacted at 65~C for 8 hours. The reaction was then cooled and filtered through cl-eeserloth. The particle size was 41 ~m and the %
20 solvent soluble portion was 59%.
This example showed that solvent could be used as a modifier to obtain a microsphere having a solvent soluble portion within 30-98%.
E~cam~e 10 E~ ,le 10 was p~epa,ed according to the procedure described in Example 9, 25 except that heptane was replaced with 20% by weight of a monomer of the tackifier resin Regelrez~ 6108 (trade name for a t~ ifier resin commercially available from Hercules, Inc.). The particle size was 55 llm and the % solvent soluble portion was 91%.
CA 0224l533 l998-06-24 W O 97126286 21 PCT~US96/18522 This example showed that a tackifier resin couid be used as a modifier to obtaina microsphere having a solvent soluble portion within 30-98%.
Example 11 To a two liter, three necked flask equipped with a thermometer mechanical 5 stirrer and nitrogen inlet tube was charged 370.0 gm of deionized water, 6.9 gm of Stepanol AMV and 3 .86 gm of Goodrite K702 which was then neutralized to a pH of7.0 with concentrated ammonium hydroxide. To this solution was added 200.0 gm ofisooctyl acrylate, 10.0 gm mineral oil (available from Paddock Laboratories, Millneapolis, ~), and 0.976 gm of Lucidol 70. ). The agitation rate was set to 400 10 rpm. The reaction mixture was heated to 65~C, purged with nitrogen and reacted at 65~C for 8 hours. The reaction was then cooled and filtered through cheesecloth. The particle size was 60 ~m and the % solvent soluble portion was 41%.
Exan~e 12 Example 12 was prepared according to the procedure described in Example 11, 15 except that 20.0 gm of mineral oil was used. The particle size was 54 llm and the %
solvent soluble portion was 62%.
F.Y~plPe 11 and 12 showed that a pl~ctir.i~er could be used as a modifier to obtain a microsphere having a solvent soluble portion within 30-98%.
Various modifications and alterations of this invention will become appal e"l to20 those skilled in the art without depal lhlg from the scope and principles of this invention, and it should be understood that this invention should not be unduly lin~ited to the illustrative embodimente set forth herein above. All publications and patents are h~COI~GI aled herein by reference to the same extent as if each individual publication or patent was speçific~lly and individually indir~ted to be incorporated by reference.
C-31% Acrylic 42 14 Acid C-4 2.5%~nH~ 40 20 Acrylate Table 4 Example A-~l eHDn Ad~ Dr Adhesion Aged Aged Total To Bond ToPSR To F Adhesion Adhesion Transfer Paper PSR F
C-l 49.8 8.1 0.1 1.6 0 26.9 C-2 61.3 14.1 0.2 8.3 0 16.1 C-3 62.5 24.2 0.3 7.3 0 4.8 C-4 71.5 22.7 0.5 8.7 0 23.4 The results in Tables 1 and 2 show that the s~mples of this invention with a lowconcentration of a chain transfer agent result in rnicrospheres which are 30 to 95%
solvent soluble and on coating make a repositionable adhesive note with improvedadhesion to painted sheet rock and fine fabric which do not decrease but improved on aging. Thus making a better repositionable adhesive.
The results with the co~ ali~e examples made without any chain transfer agent result in micros,vhc,es that have a 10-20% solvent soluble portion and on coating make a repositionable adhesive note with poor adhesion to painted sheetrock and fine fabric. The adhesion to these surfaces decreased on aging and will usually fall off of vertical surfaces.
Examples 7-8 and Comparat~ve Example CS
One gram of sodium dodecyl benzene sulfonate was dissolved in 360 grams of water. 16.8 grams of poly(ethylene oxide),6 acrylate, 7.2 grams of acrylic acid, a tnc~ifiçr (ECR-180 from Exxon Chemical) in the pelc~ es su...~ ed in Table 5, and 1.05 grarns of Lucidol-75 (75% benzoyl peroxide from Elf Atochem) were 20 dissolved in 216 grams of isooctyl acrylate. The above mixture was ~m~ ified in a WO 97126286 PCTfUS96118522 Gaulin homogenizer, such that the monomer droplet size was 1 llm or less. This emulsion was then ch&.ged to a l liter reactor, stirred at 400 rpm and heated to 65~C
for 4 hours. The r~Culti~ particle size was appru~n~ately S lum as viewed with an optical micl oscope. The % solvent soluble portion of the microspheres are S s-lmm~rized in Table 5.
Table 5 Example Wt. % TJckifier % Solvent Soluble Portion Example To a two liter, three-necked flask equipped with a thermometer, mer1l~ni lO stirrer and nitrogen inlet tube was charged 158 grams of a 0.7% solids solution of Standapol A (trade for a 28% solids solution of ammonium lauryl sulfate commercially available from Henkel Corporation), 158 grams of 1.6% solution of acrylic acid in deionized water, and enough concentrated ammonium hydroxide to neutralize the solution to pH 7. To this solution was added a solution comprised of 100 grams of 15 isooctyl acrylate, 5 grams of heptane and 0.488 grams of Lucidol 70 (trade name for a 70% active benzoyl peroxide initiator co..,...e.eially available from Pennwalt Corporation). The agitation rate was set to 400 rpm. The reaction mixture was heated to 65~C, purged with l~tl~)gen and reacted at 65~C for 8 hours. The reaction was then cooled and filtered through cl-eeserloth. The particle size was 41 ~m and the %
20 solvent soluble portion was 59%.
This example showed that solvent could be used as a modifier to obtain a microsphere having a solvent soluble portion within 30-98%.
E~cam~e 10 E~ ,le 10 was p~epa,ed according to the procedure described in Example 9, 25 except that heptane was replaced with 20% by weight of a monomer of the tackifier resin Regelrez~ 6108 (trade name for a t~ ifier resin commercially available from Hercules, Inc.). The particle size was 55 llm and the % solvent soluble portion was 91%.
CA 0224l533 l998-06-24 W O 97126286 21 PCT~US96/18522 This example showed that a tackifier resin couid be used as a modifier to obtaina microsphere having a solvent soluble portion within 30-98%.
Example 11 To a two liter, three necked flask equipped with a thermometer mechanical 5 stirrer and nitrogen inlet tube was charged 370.0 gm of deionized water, 6.9 gm of Stepanol AMV and 3 .86 gm of Goodrite K702 which was then neutralized to a pH of7.0 with concentrated ammonium hydroxide. To this solution was added 200.0 gm ofisooctyl acrylate, 10.0 gm mineral oil (available from Paddock Laboratories, Millneapolis, ~), and 0.976 gm of Lucidol 70. ). The agitation rate was set to 400 10 rpm. The reaction mixture was heated to 65~C, purged with nitrogen and reacted at 65~C for 8 hours. The reaction was then cooled and filtered through cheesecloth. The particle size was 60 ~m and the % solvent soluble portion was 41%.
Exan~e 12 Example 12 was prepared according to the procedure described in Example 11, 15 except that 20.0 gm of mineral oil was used. The particle size was 54 llm and the %
solvent soluble portion was 62%.
F.Y~plPe 11 and 12 showed that a pl~ctir.i~er could be used as a modifier to obtain a microsphere having a solvent soluble portion within 30-98%.
Various modifications and alterations of this invention will become appal e"l to20 those skilled in the art without depal lhlg from the scope and principles of this invention, and it should be understood that this invention should not be unduly lin~ited to the illustrative embodimente set forth herein above. All publications and patents are h~COI~GI aled herein by reference to the same extent as if each individual publication or patent was speçific~lly and individually indir~ted to be incorporated by reference.
Claims (18)
1. An adhesive composition comprising a plurality of polymeric, elastomeric microspheres having a 30-98% solvent soluble portion.
2. The adhesive composition according to claim 1, coated on at least a portion of at least one surface of a substrate.
3. The adhesive composition according to claim 1, wherein the plurality of polymeric, elastomeric microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4-C14 alkyl (meth)acrylate monomer and optionally at least one comonomer.
4. An adhesive composition comprising:
(a) a plurality of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4-C14 alkyl (meth)acrylate monomer and optionally at least one comonomer;
(b) an initiator for the polymerizable monomer starting materials present in amounts ranging from 0.1 to approximately 2 parts per weight per 100 parts by weight of the polymerizable monomer starting materials;
(c) optionally, a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres;
(d) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres; and (e) a modifier in an amount sufficient to produce 30-98% of a solvent soluble portion in the microspheres.
(a) a plurality of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4-C14 alkyl (meth)acrylate monomer and optionally at least one comonomer;
(b) an initiator for the polymerizable monomer starting materials present in amounts ranging from 0.1 to approximately 2 parts per weight per 100 parts by weight of the polymerizable monomer starting materials;
(c) optionally, a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres;
(d) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres; and (e) a modifier in an amount sufficient to produce 30-98% of a solvent soluble portion in the microspheres.
5 The adhesive according to claim 4 wherein the polymeric stabilizer is present in an amount of about 0.1 to about 1.5 parts by weight per 100 parts by weight of the microspheres.
6. The adhesive according to claim 4 wherein the surfactant is present in an amount of about no greater that 3 parts by weight per 100 parts by weight of the microspheres.
7. The adhesive according to claim 4 wherein the modifier is a chain transfer agent and is present in an amount of up to about 0 15%.
8. The adhesive according to claim 4 wherein the modifier is a solvent and is present in an amount ranging from 1 to 30%.
9. The adhesive according to claim 4 wherein the modifier is a tackifier or plasticizer and is present in an amount ranging from 1 to 30%.
10. A one step polymerization process for the microsphere adhesive according to claim 1 comprising the steps of:
(a) stirring or agitating a mixture comprising polymerizable monomer starting materials comprising:
(i) at least one C4-C14 alkyl (meth)acrylate monomer and optionally at least one comonomer;
(ii) an initiator for the polymerizable monomer starting materials present in amounts ranging from 0.1 to approximately 2 parts per weight per 100 parts byweight of the polymerizable monomer starting materials (iii) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iv) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weights of polymerizable monomer; and (v) a modifier in an amount sufficient to provide 30-98% of a solvent soluble portion of the microspheres;
(b) polymerizing the (meth)acrylate monomer(s) and the comonomer(s).
(a) stirring or agitating a mixture comprising polymerizable monomer starting materials comprising:
(i) at least one C4-C14 alkyl (meth)acrylate monomer and optionally at least one comonomer;
(ii) an initiator for the polymerizable monomer starting materials present in amounts ranging from 0.1 to approximately 2 parts per weight per 100 parts byweight of the polymerizable monomer starting materials (iii) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iv) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weights of polymerizable monomer; and (v) a modifier in an amount sufficient to provide 30-98% of a solvent soluble portion of the microspheres;
(b) polymerizing the (meth)acrylate monomer(s) and the comonomer(s).
11. The one-step polymerization process according to claim 10 wherein the modifier is a chain transfer agent and is present in an amount of up to about 0.15%.
12. The adhesive according to claim 10 wherein the modifier is a solvent and is present in an amount ranging from 1 to 30%.
13. The adhesive according to claim 10 wherein the modifier is a tackifier or plasticizer and is present in an amount ranging from 1 to 30%.
14. A two-step polymerization process for the microsphere adhesive according to claim 1 comprising the steps of:
(a) stirring or agitating a mixture comprising (i) at least one C4-C14 alkyl (meth)acrylate monomer;
(ii) an initiator for the monomer; a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iii) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iv) a modifier in an amount sufficient to provide 30-98% of a solvent soluble portion of the microspheres; and (v) water to form an oil in water suspension;
(b) at least partially polymerizing the polymerizable monomer starting materials;
(c) adding to the suspension at least one comonomer; and (d) continuing the polymerization of the polymerizable monomer starting materials.
(a) stirring or agitating a mixture comprising (i) at least one C4-C14 alkyl (meth)acrylate monomer;
(ii) an initiator for the monomer; a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iii) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the polymerizable monomer starting materials;
(iv) a modifier in an amount sufficient to provide 30-98% of a solvent soluble portion of the microspheres; and (v) water to form an oil in water suspension;
(b) at least partially polymerizing the polymerizable monomer starting materials;
(c) adding to the suspension at least one comonomer; and (d) continuing the polymerization of the polymerizable monomer starting materials.
15. The two-step polymerization process according to claim 14 wherein the modifier is a chain transfer agent and is present in an amount of up to about 0.15%.
16. The adhesive according to claim 14 wherein the modifier is a solvent and is present in an amount ranging from 1 to 30%.
17. The adhesive according to claim 14 wherein the modifier is a tackifier or plasticizer and is present in an amount ranging from 1 to 30%.
18. An adhesive article comprising a backing and a coating the microsphere adhesive according to claim 1 coated on at least a portion of at least one surface of the backing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/585,795 US5714237A (en) | 1996-01-16 | 1996-01-16 | Partially crosslinked microspheres |
| US08/585795 | 1996-01-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2241533A1 true CA2241533A1 (en) | 1997-07-24 |
Family
ID=24342993
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002241533A Abandoned CA2241533A1 (en) | 1996-01-16 | 1996-11-18 | Partially cross-linked microspheres |
Country Status (9)
| Country | Link |
|---|---|
| US (2) | US5714237A (en) |
| EP (1) | EP0874867B9 (en) |
| JP (1) | JP4130993B2 (en) |
| KR (1) | KR19990077206A (en) |
| AU (1) | AU724528B2 (en) |
| CA (1) | CA2241533A1 (en) |
| DE (1) | DE69623653T2 (en) |
| MX (1) | MX9805622A (en) |
| WO (1) | WO1997026286A1 (en) |
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| CN1298751C (en) * | 2004-09-14 | 2007-02-07 | 清华大学 | Process for synthesis of monodisperse micron crosslinked polystyrene copolymerization microsphere |
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| US7467873B2 (en) * | 2005-10-14 | 2008-12-23 | 3M Innovative Properties Company | Privacy film |
| GB2432338A (en) * | 2005-11-21 | 2007-05-23 | 3M Innovative Properties Co | Personalised adhesive memoboard |
| US20070147712A1 (en) * | 2005-12-19 | 2007-06-28 | 3M Innovative Properties Company | Method of making articles for storing and organizing materials |
| US20070138044A1 (en) * | 2005-12-19 | 2007-06-21 | Trotter Byron E | Article for storing and organizing materials |
| US20070140597A1 (en) * | 2005-12-19 | 2007-06-21 | Eser Ozdeger Donovan | Method of making articles for storing and organizing materials |
| DE102005062293A1 (en) * | 2005-12-24 | 2007-06-28 | Pci Augsburg Gmbh | Aqueous adhesive formulation for laying floor or wall coverings on an alkaline base, shows an acidic pH and contains polymeric binder, water, resin, filler, other additives and at least one alkali-activated thickener |
| US7494027B2 (en) * | 2006-01-27 | 2009-02-24 | 3M Innovative Properties Company | Dispenser package |
| US20080063842A1 (en) * | 2006-09-12 | 2008-03-13 | 3M Innovative Properties Company | Repositionable privacy note |
| US7547155B2 (en) * | 2006-09-15 | 2009-06-16 | 3M Innovative Properties Company | Marking device |
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| US7645355B2 (en) * | 2006-11-17 | 2010-01-12 | 3M Innovative Properties Company | Method of making a microsphere transfer adhesive |
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| KR101497733B1 (en) | 2007-06-13 | 2015-03-02 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Securable mounting material and method of making and using the same |
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| US8110280B2 (en) * | 2008-03-27 | 2012-02-07 | 3M Innovative Properties Company | Adhesive composition having non-tacky microspheres and sheets made therefrom |
| US20090270003A1 (en) * | 2008-04-23 | 2009-10-29 | 3M Innovative Properties Company | Microsphere pressure sensitive adhesive composition |
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-
1996
- 1996-01-16 US US08/585,795 patent/US5714237A/en not_active Expired - Lifetime
- 1996-11-18 WO PCT/US1996/018522 patent/WO1997026286A1/en not_active Application Discontinuation
- 1996-11-18 KR KR1019980705348A patent/KR19990077206A/en not_active Application Discontinuation
- 1996-11-18 CA CA002241533A patent/CA2241533A1/en not_active Abandoned
- 1996-11-18 EP EP96941392A patent/EP0874867B9/en not_active Expired - Lifetime
- 1996-11-18 DE DE69623653T patent/DE69623653T2/en not_active Expired - Lifetime
- 1996-11-18 JP JP52597897A patent/JP4130993B2/en not_active Expired - Lifetime
- 1996-11-18 AU AU10550/97A patent/AU724528B2/en not_active Ceased
-
1998
- 1998-07-10 MX MX9805622A patent/MX9805622A/en unknown
-
1999
- 1999-11-18 US US09/443,254 patent/USRE37563E1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE69623653T2 (en) | 2003-05-22 |
| EP0874867B9 (en) | 2003-09-10 |
| JP2000503331A (en) | 2000-03-21 |
| AU724528B2 (en) | 2000-09-21 |
| WO1997026286A1 (en) | 1997-07-24 |
| KR19990077206A (en) | 1999-10-25 |
| DE69623653D1 (en) | 2002-10-17 |
| EP0874867A1 (en) | 1998-11-04 |
| USRE37563E1 (en) | 2002-02-26 |
| US5714237A (en) | 1998-02-03 |
| AU1055097A (en) | 1997-08-11 |
| JP4130993B2 (en) | 2008-08-13 |
| MX9805622A (en) | 1998-11-30 |
| EP0874867B1 (en) | 2002-09-11 |
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Legal Events
| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDE | Discontinued |