CA1139261A

CA1139261A - Methods for bonding dissimilar synthetic polymeric materials and the products involved in and resulting from such methods

Info

Publication number: CA1139261A
Application number: CA000354451A
Authority: CA
Inventors: Seevaram N. Varadhachary; Harold Kwart
Original assignee: Congoleum Corp
Current assignee: Congoleum Corp
Priority date: 1979-12-19
Filing date: 1980-06-20
Publication date: 1983-01-11
Also published as: US4333987A

Abstract

ABSTRACT OF THE DISCLOSURE
A method of improving the bond between dissimilar synthetic poly-meric materials, such as, for example, a vinyl resin composition or material and a UV curable acrylated polyurethane resin compo-sition or material which comprises, including in the vinyl resin material (1) at least one plasticizer for said vinyl resin, (2) an organic unsaturated chemical compound soluble or dispersible in said vinyl resin composition and of sufficiently low volatility as not to be driven off during heat processing of said synthetic polymeric materials, and (3) a free radical producer or reaction initiators including in the UV curable acrylated polyurethane resin material a polythiol, bringing the vinyl resin material and the UV curable acrylated polyurethane resin material into contact, and exposing the vinyl resin material and the UV curable acrylated polyurethane material, while in contact, to curing conditions, whereby there is sufficient chemical inter-reaction between these dissimilar synthetic polymeric materials as to create a strong and permanent primary chemical bond therebetween, in addition to any secondary bonds, such as hydrogen bonds and/or attractive van der Waals forces. The present invention also relates to the products involved in and resulting from such methods.

Description

1~39Z6~

METHODS FOR BONDING DISSIMILAR SYNTXETIC POLYMERIC MATERIALS
AND THE PRODUCTS INVOLVED IN AND RESUL~ING FROM SUCH M~THODS

THE FIELD OF THE INVENTION

The present invention relates to methods of making multi-layered products, and more particularly multi-layered sheet materials, such as resilient floor coverings, which comprise a vinyl resin layer and a UV curable acrylated polyurethane resin layer, wherein it is necessary that such layers be àdhered together in a strong and permanent bond which resists dela~ination very well.

BA~KGROUND OF THE INVENTION
_ It is well known in the making of multi-layered products, such as resilient ~loor, wall or ceiling coverings, or desk, table or counter tops, and the like, that it is often necessary to bond to-gether two or more layers of dissimilar synthetic polymeric mater-ials and that it is often difficult to obtain strong and permanent bonds between such dissimilar synthetic polymeric materials.

Such difficulties often are believed to arise in the bonding of such dissimilar synthetic materials because of the difficulties created by the differences in their surface energies. For example, if atoms from two dissimilar synthetic polymeric materials cannot get close enough to each other, perhaps because of large dissimi-1~3926~

larities or disparities in polarity, attractive van der ~aals`forces cannot be adequately taken advantage of to create strong permanent bonding. Nor is it believed that hydrogen bonding can be adequately taken advantage of in such situations. Many pro-posals have been made hitherto to overcome such difficulties and to improve the bond between such dissimilar synthetic polymeric materials but none has been found to be completely satisfactory in all respects to date.

The present invention will be described with particular reference to the bonding of dissimilar synthetic polymeric materials, such as, for example, vinyl resins and UV curable acrylated polyure-thane resins but it is to be appreciated that the principles of the present invention are equally applicable to other equivalent dissimilar synthetic polymeric materials. In the same way, the present invention will be described with specific reference to multi-layered products, such as, for example, resilient floor coverings utilizing dissimilar synthetic polymeric materials but, again, it is to be appreciated that the principles of the present invention are equally applicable to other multi-layered products which also utilize dissimilar synthetic polymeric materials.

In the manufacture of resilient floor coverings, normally, a rel-atively flat base layer or substrate is laid out in substantially horizontal condition. Such a base layer or substrate i8 usually a felted or matted fibrous sheet of overlapping, intertwined fil-aments and/or fibers, usually of asbestos or of natural, synthetic or man-made cellulosic origin, such as cotton or rayon, although many other forms of sheets and films or textile materials, fabrics or the like, may be used.

Upon this substantially flat, horizontally positioned base layer or substrate is then deposited or applied a substantially uni~orm base layer of a liquid or semi-liquid resinous composition which contains a synthetic polymeric material, usually an ungelled poly-vinyl chloride plastisol and normally containing a blowing or foaming agent.

~1139 This liquid or semi-liquid plastisol vinyl resin composition i~
subsequently firmed or gelled at an elevated temperature to a relatively more stable condition by procedures which are co~-ventional and well known in the art. This relatively firm, gelled plastisol may then be printed with a decorative, mul~i-colored pa-ttern or design in which certain predetermined areas may contain a blowing or foaming i-nhibitor which subsequently modifies or alters the action of the blowing or foaming agent in those certain predetermined areas. Several different printing ink compositions may be used in such procedures.

A substantially uniform wear layer usually of a clear liquid or semi-liquid resinous composition and usually comprising another ungelled polyvinyl chloride plastisol composition but generally not containing any blowing or foaming agent is then applied as a wear resistant coating to the surface of the base layer of the printed, firmed and gelled polyvinyl chloride plastisol and i5 subsequently gelled and firMed thereon, either as a separate operation or in a Joint operation with a subsequent fusing, blow-ing and foaming operation of the base layer of polyvinyl chloride plastisol composition. Thus far, all is conventional and ~here is relatively very little difficulty in creating a stron~ End per-manent bond or adhesion between the base layer of polyvinyl chloride plastisol composition and the wear layer which is also a polyvinyl chloride plastisol composition.

It is then frequently desired to provide a top surface coating to the surface of the polyvinyl chloride plastisol wear layer and it is o~ten desired that such top surface coatin~ be a UV
(ultra violet~ curable acrylated polyurethane resin, primarily because of its superior physical and chemical characteristics and properties. However, in many instances, it is found that ~he ad-hesion or bond between the vinyl resin wear layer and the W cur-able acrylated polyurethane resin top surface coating is not as ~i392~

s-tron~ or as permanent as desired or required, especially in the final product. It is believed that such lack of strength and of permanency or lack of suitable resistence to delamination is due in part to the fact that the wear layer and the top surface coating are dissimilar synthetic polymeric materials.

PURPOSES AMD OBJ~CTS O~ THE INVENTION

It is therefore a principal purpose and object of the present invention to provide for methods of improving the bond between dissimilar synthetic polymeric materials, and particularly be-tween a vinyl resin material and a UV curable acrylated polyure-thane resin material, whereby a strong, permanent bond is created between such materials which will resist delamination very well.

BRIEF SU~ARY OF ~XE INVENTION

It has been found that such principal purpose and object, as well as other principal purposes and objects which will become clearer from a further reading and understanding of -this dis-closure, may be achie~ed by forming a layer comprising avinyl resin, one or more plasticizers for the vinyl resin, a rela-tively non-volatile organic olefinically or acetylenically un-saturated chemical compound soluble or dispersible in the vinyl resin layer and of sufficiently low volatility as not to be driven off during elevated temperature heat processing o~ the vinyl resin layer, and a free radical producer or reaction ini-tiator; forming a layer comprising a UV curable acrylated poly-urethane resin and a polythiol; bringing the vinyl resin layer and the UV curable acrylated polyurethane resin layer into con-tact; and exposing the vinyl resin layer and the UV curable acrylated polyurethane resin layer, while in contact, to curing conditions, whereby there is sufficient chemical i.nter-reaction . _ , . .. .. _ _ . -- _ . , ~ , _, .. .

1~3926~

between the vinyl resin layer and the UV curable acrylated poly-urethane resin layer as to provide a strong and permanent bond therebetween~ in addition to any secondary bonds such as hydro-gen bonds and a-ttractive van der Waals forces, such strong and permanent bonds comprisin~ primary chemical bonds very well cap-able of resisting delamina-tion.

DESCRIPTION OF PRE~ERRED AND TYPICAL E~BODIi~ENTS

THE ~ASE IAYER OR SUBSTRATE

The specific base layer or aubstrate which i5 used to illustrate the preferred and typical embodiments of the present invention do not relate to the essence of the inventive concept and no specific or detailed description thereof is deemed necessary.
In many cases, it may be omitted entirely but, customarily, it is a conventional felted or matted fibrous sheet of overlapping, intermingled fibers and/or filaments, usually of mineral origin, such as asbestos fibers, or of cellulosic origin, such as cotton or rayon, although many other forms of sheets, films, or fabrics, and many other fibers and/or filaments of natural, synthetic or man-made origin, may be used, as described in United States Patents 3,293,09~ and 3,293,108 to Nairn et al.

THE BASE SYNTHETI~ PO~Y~r~RIC LAYER

The specific base synthetic polymeric layer which is used to illustrate the present invention does not rela-te to the essence thereof and it is sufficient to state that it may be any poten-tially foamable or non-foamable resinous composition known to the art but that,although a plastisol of polyvinyl chloride is pre-ferred and is typical, many other synthetic resins are also of use not only as plasti601s ~ but also as organosols or as aqueous la-tices.

~i3926~ -Typical of the plasticizers which are used in the formation o~
polyvinyl chloride plastisols are dioctyl phthalate, tricresyl phosphate, butyl benzyl phthalate, dibutyl sebacate, didecyl adipate, dioctyl sebacate, and many others cited in the prev-iously mentioned United States Patents, generally in conventional amounts and percentages set forth in such patents.

THE VINYL RE~IN WEAR LAYER
.
The specific vinyl resin which is used in the preparation of the wear layer does not relate to the essence of the present inven-tion, Although a polyvinyl chloride homopolymer or a blend of two or more polyvinyl chloride homopolymers in the form of a plastisol is the preferred and typical embodiment, many other vinyl resins, either in the form of a plastisol, or an organosol or an aqueous latex, are of use, such as, for example, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinylidene chloride copolymeri or copolymers of vinyl chloride with other vinyl esters, such as vinyl butyrate, vinyl propionate, or alkyl substituted vinyl esters, and the liXe. Other synthetic polymers are also of use.

~ubstantially any vinyl resin wear layer will suffice, such as those disclosed~the previously mentioned United States Patents, with the modification that there also be included in the formu-lation from about O.5 percent to about 10 percent by weight, and preferably from about 2 percent to about 8 percent by weight, of a relatively non-volatile olefinically or acetylenically unsatu-rated organic chemical compound readily soluble or dispersible in the vinyl resin wear layer and of sufficiently low volatility as not to be driven off during subsequent elevated temperature heat or other processing of the vinyl resin wear layer, and from about 0.04 percent to about 2 percent by weight, and preferably from about O.l percent to about 1 percent bJy~teight, of a free radical producer or reaction initiator, ~ k~h=~ to the aforementioned plasticizer or plasticizers and other conventional ingredients of the vinyl resin wear layer.

li3!~Z6~

THE UN~ATURATED CH~I~ICAL COI,.POUND

Substantially any olefinically or acetylenically unsaturated chemical compound can be used as the additive to the vinyl resin wear layer, provided it is soluble or dispersible therein and possesses sufficiently low volatility and will not be driven off from the vinyl resin wear layer during elevated temperature heat processing or other processing subsequently ernployed and also provided it i6 capable of reacting with thi~l radicals ( S- ) in a radical addition process wherein the thiyl radicals are de-rived from polythiols containing two, three, four or more thiol functions ( -SH ) which are included in the W curable acrylated polyurethane re~in composition to be described in greater detail hereinafter and to which the vinyl resin wear layer is to be ad-hered and bonded.

Unsaturated triglycerides, that is, derivatives of glycerol wherein the hydroxy groups have been esterified by unsaturated acids are of particular use within the principles of the present invention. Examples of suitable unsaturated fatty acids which are readily aYailable include~ undecylenic acid, palmitoleic acid, oleic acid, riciboleic acid, petroselinic acid, vaccenic acid, lin-oleic acid, linolenic acid, eleostearic acid, licanic acid, pinaric acid, tariric acid, gadoleic acid, arachidonic acid, cetoleic acid, erucic acid, selacholeic acid, nervonic acid, and other unsaturated acids which may be mentioned hereinafter.

~ All of the hydroxy groups o~ the glycerol need not be esterified A by the same unsaturated ~ois but two or more different unsaturated acids may be present in the esterification process. And, it is not necessary that all three hydroxyl groups of the glycerol be esterified. In many cases, only one or two of the hydroxy groups need to be esterified by the unsaturated acid or acids, thus yield-ing monoglycerides and/or diglycerides.

1~39Z61 Although glycerol is the preferred and typical polyol to be est-erified by the unsaturated acid or acids, other polyols are also capable o~ utilization within the principles of the present in-vention. Diols or glycols, such as ethylene glycol, propylene glycol, trimethylene glycol, etc., are also of use, as well as higher polyhydroxy alcohols, such as erythritol, pentaerythritol, etc., for the esterification with the unsaturated acid or acids to yield the corresponding mono~esters or diesters or polyesters.
Again, different unsaturated acids may be employed in such ester-ification processes.

Where the unsaturated acids referred to previously are not o~
high volatility and will not be driven off during conventional heat or other processing of the vinyl resin wear layer, such as in the case particularly of ricinoleic acid, oleic acid, palmit-oleic acid, linoleic acid, and linolenic acid, they may be used as such, provided their acidity is not such as to constitute a a deleterious or objectionable effect upon the vinyl resin we~r layer or upon other adjacent layers or other contacting or con-tiguous materials.

Oils and fats which are soluble or dispersible in the vinyl wear layer and have sufficiently high boiling points and low volatil-ity are also o~ use. Plant, vegetable, animal and marine drying oils are of particular applicability. Such would include raw or dehydrated castor oil, linseed oil, oiticic~ oil, soya bean oil, tung oil, safflower oil, tall oil, fish oil~ cottonseed oil, corn oil, perilla oil, etc. All,of these oils contain hlgh percentages of unsaturated acids and all have Iodine Values in excess of about 80 and in some instances up to 200 or even more. Oils and fats, other than drying oils, are also suitable for application within the principles of the present invention, where such oils or fats are soluble or dispersible in the vinyl resin wear layer, have the necessary high boiling points and low volatilities, are un-saturated and possess Iodine Values in excess of about 80. ~uch would include, for example, olive oil, peanut oil, sperm oil, rape or rapeseed oil, etc.

1~39Z6~ -Other unsaturated esters of lower molecular weight unsaturated acids, ~uch as, for example, maleic acid and fumaric acid esters, of suitable solubility or dispersibility and of relatively high boiling points and/or low volatility are also of applicability.
Examples of such lower molecular weight unsaturated acids are maleic and furnaric acids, acrylic acid, methacrylic acid, pro-piolic acid, crotonic acid, isocrotinic acid, citraconic acid, mesaconic acid, cinna~ic acid, allocinnamic acid, angelic acid, tiglic acid, elaidic acid, vinyl acetiç acid, etc. Satura~ed or unsaturated hydroxy compounds may be used in such esterification processes with such unsa-turated acids to yield the esters having the requisite unsaturation.

Unsaturated esters derived from unsaturated alcohols and fatty acids are also of value and of use in the application of the prin-ciples of the present invention. Examples of such unsaturated alcohols include, as illustrative but not limitative, 2-propen-1-ol (allyl alcohol), 2-methyl-2-propenol-l~ol (methallyl alcohol),

2-buten-1-ol (crotyl alcohol), 3-buten-1-ol, 3-buten-2-ol, l-pen-ten-3-ol (ethyl vinyl carbinol), 4-penten-1-ol, 4-penten-2-ol (allyl methyl carbinol), 2-butyn-1-ol, 3-buty~-1-ol, 3-butyn-2-ol, 2-butyn~ diol, 3-butyn-1,2-diol, 1-hexen-3-ol, 3-hexen-1-ol, 4-hexen-1-yne-3-ol, 2-hepten-4-ol, etc. The fatty acids useful for esterifying such unsaturated alcohols are preferably and typically the lower fatty acids up to four or more carbon atoms.
Again, such esterifying acids may be saturated or unsaturated, and as long as the resulting unsaturated esters have the required sol-ubility or dispersibility properties and characteristics, along with sufficiently high boiling points and sufficiently low vola-tility values.

Where such unsaturated alcohols are not of high volatili-ty and will not be driven off at the elevated temperatures of the heat or other processing involved, and have the other herein listed required properties and characteristics, they may be used as such in the formulation of the vinyl resin wear layer.

~139Z6~

Unsaturated arnidesare also applicable within the principles of the present invention, again where such unsaturated amides are able to meet the solubility or dispersibility requirements pre-Viously mentioned herein as well as the sufficiently low vol-atility so as not to be driven off during any elevated tempera-tures of subsequent heat or other processing of the vinyl resin wear layer. Such unsaturated amides include, as illustrative but not limitative, N,N-dibutyl maleamide, N,N-dioctyl cro-tonamide, N,N'-dibutyl maleic acid diamide, etc.

Under normal circumstances, the greater the degree of unsaturation of the unsaturated olefinically or acetylenically bonded chemical compounds, the greater is their applicability to the principles of the present invention. One measure of the degree of unsaturation of such chemical compounds is the determination of its Iodine No.
(or Iodine Value) which is the number of grams of iodine that will combine with one hundred grams o~ the unsaturated chemical com-pound. Such an Iodine absorption rlumber is an accurate and excell-ent measure of the unsaturated linkages present in the fat, oil, unsaturated acid, or other chemical compound being evaluated.
~'ithin the scope of the present invention, it has been found that Iodine Values in excess of about 80, and preferably above about 125, are utilizable.

THE PLAS~ICIZERS

The plasticizers which are incorporated in the formulation of the vinyl resin wear layer are conventional and may be selected from many well-known plasticizers now available commercially. A few have been named previous,ly,herein as exemplary of a vast number of other suitable ~ The particular plasticizer which i6 selected does not relate to the essence of the present inven-tive concept. Such plasticizer or plasticizers are present in conventional amounts and concentrations.

THE ~REE RADICA~ PRODUCER OR REACTION I~ITIATOR

In addition to the unsaturated chemical compound, the plasticizer or plasticizers, and other desired or required additives, there i8 al80 included in the formulation of the vinyl resin wear layer from about 0.04 percent to about 2 percent by weight, and pre-ferably from about O.l pe~cent to about 1 percent by weight, of a free radical producer or reaction initiator. The particular free A radical producer or reaction initiator r~hich is selecte~d for the application of the principles of the present invention ~ not re-late to the essence o~ the inventive concept but depend~ upon factors such as the particular elevated temperature heat process-in~ conditions which exist in the manufacture of a 6pecific pro-duct. In other words, the free radical producer or reaction in-itiator must be activated at a particular temperature and time in the manufacturing process and not prematurely or too late or not at all. Examples of typical ~nd preferred free radical producers or reaction initiators are benzoyl peroxide, lauroyl peroxide, dicumyl peroxide, and many others which are available commercially~
These would include not only per-compounds such as organic per-o~ides but also hydroperoxides, dialkyl peroxy dicarbonates, and other peroxy compounds, such as t-butyl peroxy acetate, t-butyl peroctoate, t-butyl peroxy-2-ethylhexanoate, t butyl perbenzoate, and many others.

FORMATION AND GELLING OF THE VINYL RE~IN WEAR LA~ER
. . .
The vinyl resin wear layer formulation including one or more plasticizers for the vinyl resin, together with filler6, 6tabili~-ers, etc., and containing the olefinically or acetylenically un-saturated chemical compound and the free radical producer or re-action initiator is then cast or formed on the surface of the previously mentioned base synthetic polymeric firmed and gelled plastisol composition o~ polyvinyl chloride.

~139Z61 The vinyl resin wear layer has a substantially uniform thickness normally in the range of from about 2 mils to about 30 mils or more. The vinyl resin wear layer is then gelled and firmed, either in a separate operation at an elevated temperature of from about 240 ~. to about 430 F. for a period of time of from about 1 minute to about 4 minutes, or in a combined operation, together with a fusion and blowing or foaming procedure, if a blowing or foaming agent was originally included in the formu-lation of the base synthetic polymeric layer. Such ~usion and blowing temperatures are normally in the range of from about 270 F. to about 450 F. and extend over a period of time of from about 2 minutes to about 10 minutes, and preferably from about

3 minutes to about 8 minutes.

The above temperature ranges indicate the normal elevated temp-erature heat processing ranges employed for the application of the principles of the present invention and are determinative of the particular unsaturated chemical compound selected to be in-cluded in the particular vinyl resin wear layer to be used in the particular application of the principles of the present invention.
This is dictated by the fact that such unsatu~ated chemical com-pound should have a boiling point higher than the particular heat processing temperature involved and have a su~ficiently low vol-atility that it is not driven off ~rom the vinyl resin wear layer during such heat processing.

T Æ TOP SURFACE COATING

The specific ultraviolet (UV) curable acrylated polyurethane which is used in the formulation of the top surface coating which is ap-plied to or formed on the vinyl resin wear layer does not relate to the essence of the present invention and may be selected from a relatively large group of presently available acrylated poly-urethanes.

1~39Z61 rrHE W CURABLE ACRYLA'l'~ POLYURETHAN~S
.~odified polyurethanes, such as the ultraviolet curable acrylated polyurethanes, may be prepared by several different manufacturing methods, one preferred and typical manufacturing method using three basic com~onents: (1) a W reactive polymer; (2) a diluent system com~osed of multiiunctional acrylate esters (and occasionally monofunctional acrylie esters); and (3) a ~hotoinitiator system.
Such modified or aerylated polyurethanes are well known in the prior art and speeific detailed ~escription of conventional methods of their manufacture is not believed necessary. It is believed sufficient to state that additional details of such manufacturing methods, and particularly the polyisocyanates, the polyfunctional compounds (especially the polyols), and the hydroxyalkyl acrylates used therein are to be found in related, copending Canadian patent applications Serial Nos. 336,072 and 336,073, filed September 21, 1979.
Substantially the sole difference between such prior art methods of manufact~ring such mDdified or W curable acrylated polyurethanes is the modification that there be included in t~e final formulation from about 1 percent to about 10 percent by weight, and preferably from about 2 percent to about 8 percent by weight of a polythiol or polymercaptan containing at least 2, 3, 4 or more -SH functions.
rrHE POLYr~IOL OR_PO YME CA rAN
~le particular po]ythiol or polyme:rcapLan containing at least 2, 3, 4 or more -SH functions which is sel.ected for the application of the principles of the present invention depends pr:unarily on mb/ ~ - 13 -the heat processing temperatures and conditions which exi~t in the manuf~cture of the ~peci~ic product involved, upon the ~ub~
sequent use and intended purpose of such specific product, upon the speclfic phys~cal and chemical propertie~ and char~cterist~ C8 de~ired in such spec~fic product, and 80 on. The particular polythiol may be selected from a rel~tively large group of ~uch sulfur-containing compounds presently ~vailable commerci~lly.
Such group includes the following, as illu~tr~tive of 6uch eom-pounds but not limitative thereof.

2, 2'-d~mercapto diethyl ether Dipentaerythritol hexa(3-mercaptopropion~te) Dithiolterephthalic acid Glycol dimerc~pto acetate Glycol.dimercapto propion~te Pentaerythritol,tetra(3-mercaptopropionate) Pentaerythritol tetrathioglycol~te Polyethylene glycol dimercapto acetate Polyethylene glycol di(3-mercaptopropionate) Trimethylolethane tri(3-mercaptopropionate~
trimethylolethane trithioglycolate Tr~methylolpropane tri(3-mercaptopropionate) ~rimethylolpropane trithioglycolate Ethylene dimercaptan 1, 3-propanedithiol 1, 4-butanedithiol glycerol dimercaptopropionate Curing condition~ for thè UV curable acrylated polyureth~nes dif-fer from tho~e employed for more conventional polyurethanes in that such acrylated polyurethanes are cured by being passed thru an actlnic radiation source such as'an ultraviolet lamping unit.
R~diation curing by electron beam, gamma and x-ray treatment, and other suitable radiation sourceæ may be employed but must be used at relatively low energy levels, inasmuch as they ~re es-sentially example~ of very h~gh energy irr~diation techniques leading to extremely rapid polymerization. Ultraviolet radi-ation i8 the preferred and typic~l ~ource. In the presence of photoinitiators, such radi~tion source6 ind~ce a photochemical reaction which produces free radlc~l~ capable of inducing poly-merization. Source~ of ultraviolet radiation may be mercury v~por arc l~mp8~ plasm~ arcs, pulsed xenon l~mp~ ~nd carbon arcs. Mercury Yapor arc lamps are preferred and typic~l, pre-ferably at medium pressure, rather than high pressure or low pre~sure. Specific wavelengths of l~ght ~hich ~re most effec-tive will vary, depending primarily upon the particular poly-urethane top surface coating formulation used and the p~rticu-lar photosensitizer employed. It i~ a1BO to be appreciated that in some instances 9 combination~ of thermal curing and radiat~on curing conditions may be used.

During the curing conditions to which the ultraviolet cur~ble acrylated polyureth~ne resln i~ exposed, there i8 su~ficient chemical inter-reaction between the olefinic~lly or ~cotlyeni-cally unsaturated chemic~l compound in the vinyl resin wear l~yer and the polythiol or polymercapt~n in the acrylate~ poly-ureth~ne re~in top surf~ce coating a8 to create a strong and permanent primary chemical bond between the two layers of dis-similar synthetic polymeric materials. Such, of aourse, i8 ad-dit~on~l to any existlng secondary bondc or force~, ~uch as hydrogen bonds or attractive ~an der Waals forces.
,:

The fundamental chemical re~ction producing the strong bonding linkage between the vinyl resin we~r layer and the acryl~ted polyurethane re~in layer is initiated by carbon and/or oxy free ... ...
radical~ formed via the decomposition of the free radical pro-ducer or reaction initiator (normally an organic peroxide or hydroperoxide) in the vinyl resin wear layer.

1:1392~1 A carbon or oxy free radic~l reacts with an -SH (thiol) function which has somehow crossed the boundary into the ~inyl resin we~r layer from the acrylated polyureth~ne resin layër, whille part or all of the remainder of the polythiol or polymercaptan molecule which it comprises i8 tied by 6trong chemical bonds to the acryl-ated polyureth~ne layer in which formulation it was originally included. The reaction between the c~rbon or oxy free radical (R- or R0-) and the-SH group which has migr~ted into the vinyl resin wear l~yer or its boundaries i8 known ~s a hydrogen atom-abstraction giving rise to a thiyl (-S-) radical, as expre~sed by the following equation~

R- + HS~ RH ~ S-The thiyl r~dical iB cap~ble o* rapid addition to an olefinic or ~cetylenic unsaturated compound present in the formulation o* the vinyi re~in wear layer, as expressed by the following equationt ~ ~ .
-S~ = C~ S-C-C-The carbon free radical i8 fully capable of continuing the ch~in:
re~ction, as expressed in the above chemical equations, until ter-minated in-a bimolecul~r recombination step, such a~ expressed in the following equation~

R- ~ R~ R-R (inert) In this f~shion, all -SH function~ in the acrylated polyurethane resin layer ~hich have diffused into or have been dis~ol~ed into the vlnyl resin wear layer or its boundaries with the acrylated polyurethane resin layer have been incorporated in a sulfur-carbon bond of great strength between the vinyl resin wear layer and the acrylated polyurethane re~in layer. This strong ohemical bond i8 the source of .the excellent adhesion realized by such an anchoring chemical reaction.

~39Z~il In the possible event that the applied and adhered top 6urface coating of an ultraviolct curable acrylated polyurethane is to be ~ubsequently cured in a combined operation involving the use of an actinic radiation source together with a thermal curing operation at elevated temperatures, it is to be observed that the temperatures of such a thermal curing operation be prefer-ably within the ranges previously set forth for the blowing or foaming and fusing operations on the synthetic polymeric resin~
used, or lower, but not higher.
, The present invention will be further de~cribed w~th particular reference to the following specific working examples, wherein there are disclo~ed many preferred and typical embodiment~ of the present inventive concept. However, it is to be pointed out that such speciric working example~ are primarily illustrativs and not limitative of the broader aspects of the present inven-tive concept and that other specific ~aterials, chemi¢als, pro-cesses, etc., may be employed without departing from the ~cope and the spirit of the appended claims.

EXAMPI,E I

The base layer or substrate compr~ ses a relatively flat, 0.040 inch thic~ ribrous sheet of felted, matted asbestos ~ibers with an acrylic resin smoothing or leveling coating thereon. The asbestos fibrous sheet i8 coated substantially uni~ormly to a wet thickness depth of about 0.015 inch with the following fozm-able poly~inyl chloride pla6tisol composition as the base syn-thet~c polymeric layer~
Parts Polyvinyl chloride, low mol. wt., general purpose, d~spersion resin, inh. viscosity 0.99 ~ASTM 1243-66) 30.2 Polyvinyl chloride, med. mol. wt., disper~ion grade, inherent visc08ity 1-0 8.2 Poly~inyl chloride, med. mol. wt., blending resin, inherent visco~ity 0.9 17.1 Anhydrous aluminumsilicate filler 6.9 Alkyl benzyl phthalate plasticizers 24.7 Polydodecyl benzene 7.4 Azodicarbonamide blowing agent 1.1`
Accelerator/stabilizer 0.4 Tit~nium dioxide 2.5 Dioctyl phthalate 1.5 Wetting agent o.o3 (Parts by weight) Gelling and firming of the potentially foamable polyvinyl chlor-ide plastisol compos~tion is accomplished in a heated oven atmosphere maintained at an elevated temperature of about 300 F.
~or a period of time of about 3 minutes. This temperaturc 18 not that elevated as to activate or to decompose the azodicarbon-a~ide blowing or ~oaming agent in the polyvinyl chlorid~ base synthetic polymeric composition layer as to cause blowing or foamin~ thereof.

The gell~d, f irmed, potentially foamable polyvinyl chloride plaBti80l i6 then printed with a multicolored decorative de~n or pattern, using (1) a con~entional or 6tandard printing ink composition and (2) an inhibitor-containing printing ink compo-sition, ha~ing the following composit~ ons, re~p~cti~elyt Parts Solution-grade vinyl chloride-~inyl acetate copolymer (90 parts~ 10 parts) ~5 Methyl ethyl ketone 85 -Pig~ent or colorant, as desired or required Part~
Solution grade ~inyl chloride-vinyl acetate copolymer (90 parts~ 10 parts) 12 Methyl ethyl ketone 68 Trimellitic anhydride blowing ~nhib~tor 20 Pigment or colorant, as desired or required The printed, gelle~ potentially foamable polyvinyl chloride pla8ti801 i8 then allowed to air-dry and a polyvinyl chloride plastisol ~ear layer ~8 sub~tantially un~formly applied thereto to a ~et thickne~s depth of about 0.015 inch. The wear layèr has the ~ollo~ing compo~ition formulation by weight~
Parts Polyvinyl chloride, aisp~rsion grade, high mol. wt. 89.4 Poly~inyl chloride, blending re~in, inh. ris. 0.9 10.6 Butyl benzyl phthalate plasticizer 28.9 2,2,4-trimethyl-1,3-pentanediol dlisobutyrate 6.9 Plastioi~er (S-374) 5.0 Toner - ~ 0.21 Glycerol diundecylenate 5,0 Benzoyl peroxide 0.3 Dibutyl tin dilauratc 3.o i~392f~1 Gelling and firming of the applied polyvinyl chloride pla~ti~ol wear layer takes place at an elevated temperature of about 300 F. in a heated oven atmosphere for a period of time of about 3 minute~, subse~uently followed by a blowing or foaming and fusing operation at a neces6arily higher temperature of about 430 F.
for a period of time o~ about 2 minute~. Such ele~ated tempera-ture6 are not sufficiently high as to a~fect or to driva off the unsatura~ed glycerol diundecylenate from the vinyl wear layer.

The polyvinyl chlorid~ resin wear layer i8 then coate~ with a ~ub~tantially uniform wet th~cknes~ depth of 1~ mils of an ultra-~iolet curable acryiated polyurethane re~in top coating surface prepared from the following ~sterials~

~V curable acrylated polyurethane ~au-24 deri~ed from 3 -NCO equivalent~ of methylene-bi~(4-cyclohexylisocyanate), 0.9 -OH equi~alents of 2-hydroxyethyl acrylate, and O.9 -0~ equivalents o~,Pluracol 410 polyether tetrol. 26.0 gms.
*
UV curable acrylated polyurethan~ Lau-17 deri~ed from

4 -NCO equi~alents of methylene-bis(4-cyclohexyli~ocyanate) and 2.4 -OH equi~alent~ Or Z-hydroxyethyl acrylate 4.4 gm8 .

Polyoxypropylene tetrol based on pentaer~thritol, mol. wt. 600, hydroxyl no. 374 (Pluracol 410) 4.6 gms.

Vinyl acetate 15.0 gm~.

To thi~ i~ addedl ~ibutyl tin dilaurate 5 drops I~obutyl ether o~ benzoin 1.5 cc.

Pentaerythritol tetrath~oglycolato 2.5 gms.
t-~ e ~ h 1139;~61 Th~ curing of the applied UY curable acrylated polyurethane resin top surface coating takes place by passag~ through an ultraviolet unit at a rate of about 10 ~eet per m~nute. The ultrav~olet unit has a length of about 3 feet (2 lamp parallel unit, 12 inches long, 200 watts each lamp, medium pre~sure, mer-cury lamp) and a nitrogen atmosphere.

The bond between the ~inyl re~in wear layer and the acrylated polyurethane resin top surface layer iB tested and is found to be very strong and permanent. It i8 ~ell capable o~ re~isting delaminating force~ ~ery ~ell. Primary chemical bonds exi~t between the two dissimilar synthetic polymeric layer~.

EXAMPLES II-IV _ The procedures de~cribed in ~x~mple I are followed substantially as set forth therein with the exception that the pentaerythritol tetrathioglycolate in the acryl~ted polyurethane top surfaco layer is replaced by an eqùivalent stoichiometrical amount o~

Example II. Trimethylol propane trithioglycolate, Example III. Trimethylol ethane trithio~lyc~late, and Example IV. Poiyethylene glycol dimercaptoacetate.

The results of the~e Example~ are generally comparable to the result6 obtained in Example I. Good adhesion i8 noted a~ exist-ing between the vinyl resin wear layer and the acrylated poly-urethane resin top coating. Primary chemical bonds exist betweén the two dis3imilar synthetic polymeric layers and delamination resisted very well.

113926~

EXAMPLE V
. .
The procedure6 de~cribQd in Example I are followed 6ub~tanti~1ly as ~et f orth therein with the exception that the amount of the pentaeryth~tol tetrathioglycolate i~ reduced to half the amount set forth in Example I. The r¢sults o~ this Example are gener-ally comparable to the results of Example I~ Good adhe~ion i6 noted as existing between the t~o di~imilar synthetic polymeric layer~. Delamination i~ re~isted very well. Primary chemicat bonds exist as before.

.
~XAMP~ VI
.
The procedures described in Exa~ple I are followed substantially aæ 6et forth therein with th~ exception that the 5 part~ of tl3e glycerol diundecylenate i8 replaced by 5 parts of glycol un-decylenate. The re~ult~ of this Example are generally comparlibl~
to the result~ obtained in Example I. Good adhe~ion is not¢d a~
existing between tho two di~similar synthetic polymeric layer~.
Delaminatio~ iB resi~ted very ~ell. Primary chemical bond~ are in exi~tence between the two layer~.

EXAMPLES VII-VIII
, The procedures described in Example I are followed substantia~
as set forth therein ~ith the exception that the proportions cf the polyvinyl chloride re~ins in the vinyl resin wear layer f~r-mulation is changed to 50~50 and the glycerol diundecylenate 1~
replaced by an equivalen~ stoichiometrical amount of dibutyl r;al-eate (Example VII) and dibutyl iumarate (Ex~mple VIII). The ~e-sults of the6e Examples are generally comparable to the resul's obtained in Example I. Good adhesion is noted as existing be t~een the two dls~imilar synthetic polymeric layers. Primary chemical bond3 exi~t.
:

EXAMPLES IX-XXII

The procedure6 described in Example I are ~ollowed substantially as set forth therein ~ith the exception that the glycerol d~-undecylenate i6 replaced by the following drying o~l~a Example IX. cp castor oil Iodine No. 88 ~Example X. dehydrated ca~tor oil Iodine No. 125-140 Example XI. "Synthenol'~ Iodine No. 130 ~xample XII. ~Synthenol GH" Iodine No. 140 Example XIII. Raw lin~eed oil Iodine No. 170-190 Example XIV. Superlor lin~eed o~l Iodine No. 190 Example X~. Tung oil . Iodine No. 165 Example XYI. Soya bean oil Iodine ~o. 140 Exa~ple XVII. Fish oil Iodine No. 19~
Exa~ple X~III. Crude Tall oil Iod$ne No. 143 Example XIX. Saffiower oil Iodine No. 145 ~xample XX. Oiticica oil Iod~ne No. 16~
Example XXI. Raw castor oil Iodine No. 83 Exa~ple XXII. Cottonsee~ oil Iodine No. llO

The result6 of these Example~ are generally comparable to the results obtained in Example I. Good adhe~ion exi~ts between the two synthetic polymeric layers and delamination i8 succes~fully resi~ted very well. Primar~ chemical bond~ exi8t between the Yinyl resin wear layer and the acrylated polyurethane sur~ace layer.

EXAMPLES XXIII-XXYI

The procedures described ln ~xample I are followed ~ub~tanti~lly a~ set forth therein with the exception that the glycerol d~un decylenate i8 replaced by the following oils~
rc~ rh ~1392~:~

Example XXIII. Olive oil Iodlne No. 85 Example XXIV. Peanut oil Iodine No. 90 Example XXV. Rape oil Iodine No. 94 Example XXVI. Sperm oil Iodine No. 84 The results of these Examples are generally comparable to the results obtai.ned in Example I. Good adhesion exi~t~ between the vinyl resin wear layer and the acrylated polyurethane re~in top surface layer. Primary chemical bonds exist therebetween., De-lamination is resisted ~ucce~fully very well.
.
'', ' EXAMP~ES XXVII-XXVIII
,. ~ . . .
The procedures described in Example I are followed su~stantially a6 set ~orth there~n with the exception that the 3 parts of di--butyl tin dilaura*e i8 replaced by 3 parts of dibutyl tin bis-(monoalkylmaleate) (Example XXVII) and by 3 pa~t~ of dibutyl tin biæ(monoalkylmaleate) along ~ith the replacement of the glycerol diundecyienate by glycol undecylenate similar to Example VI
~Exampie XXYIII).

The re6ultæ of these Examples are generally comparable to th~
results obt~ined in Examples I and YI. Good adhesion i8 noted bet~een the two dissimilar æynthetic polymeric layers and de-lamination i5 resisted very well. Primary chemical bonds are in existence.bet~een the two layers.

~lthough numerous specific Working Examples of the inventive con-cept have been described in great particularity, the ~ame should not be construed as limitative of the broader aspects of the in-vention but as merely illustrati~e of speci~ic material~ and pro-cedure~ which are preferred ~nd typica~. Other materials and other procedure~ may be used, a~ ~ell as other equivalent feature~
and aspects, without departing ~rom the ~pirit and the ~cope oi the appended claim~.

Claims

WHAT IS CLAIMED IS:

1. A multi-layered construction of dissimilar synthetic poly-meric materials comprising:

a first layer of a synthetic polymeric composition comprising a vinyl resin, at least one plasticizer for said vinyl resin, an organic unsaturated chemical compound soluble or dispersible in said vinyl resin synthetic polymeric composition and of suf-ficiently low volatility as not to be driven off during heat processing of said multi-layered construction, and a free radi-cal producer or reaction initiators and a second layer of a synthetic polymeric composition comprising an ultraviolet-curable acrylated polyurethane resin and a poly-thiol capable of reacting with said organic unsaturated chem-ical compound in said first layer to form permanent primary chemical bonds bonding said layers together.

2. A multi-layered construction as defined in claim 1 wherein said polythiol is pentaerythritol tetrathioglycolate.

3. A multi-layered construction as defined in claim 1 wherein said polythiol is trimethylol propane trithioglycolate,

4. A multi-layered construction as defined in claim 1 wherein said polythiol is trimethyiol ethane trithiogiycolate.

5. A multi-layered construction as defined in claim 1 wherein said polythiol is polyethylene glycol dimercaptoacetate.

6. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is an unsaturated glyceride.

7. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is glycerol di-undecylenate.

8. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is an unsaturated ester.

9. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is glycol undecylenate.

10. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is dibutyl maleate.

11. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is derived from a drying oil.

12. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is derived from a drying oil having an iodine number of at least about 80.

13. A multi-layered construction as defined in claim 1 wherein said organic unsaturated chemical compound is derived from dehydrated castor oil.

14. A multi-layered construction of dissimilar synthetic poly-meric materials comprising:

a first layer of a synthetic polymeric composition comprising a vinyl resin and at least one plasticizer for said vinyl resin;
and a second layer of a synthetic polymeric composition comprising an ultraviolet-radiation cured acrylated polyurethane resin, said layers being bonded together by permanent primary chemical bonds formed of reaction products of an organic unsaturated chemical compound soluble or dispersible in said vinyl resin synthetic polymeric composition and of sufficiently low vola-tility as not to be driven off during heat processing of said multi-layered construction and a polythiol.

15. A method of forming a multi-layered construction of dis-similar synthetic polymeric materials comprising:

forming a first layer of a synthetic polymeric composition com-prising a vinyl resin, at least one plasticizer for said vinyl resin, an organic unsaturated chemical compound soluble or dis-persible in said vinyl resin synthetic polymeric composition and of sufficiently low volatility as not to be driven off during heat processing of said multi-layered construction, and a free radical producer or reaction initiator;

forming a second layer of a synthetic polymeric composition com-prising an ultraviolet-curable acrylated polyurethane resin and a polythiol capable of reacting with said organic unsaturated chem-ical compound in said first layers and exposing said first layer and said second layer to curing condi-tions, while in contact, for said ultraviolet-curable acrylated polyurethane resin, whereby said organic unsaturated chemical compound reacts with said polythiol to create strong and perma-nent primary chemical bonds between said layers.

16. A method as defined in claim 15, wherein said curing con-ditions include actinic radiation.

17. A method as defined in claim 15, wherein said curing con-ditions include ultraviolet radiation.

18. A method as defined in claim 15, wherein said curing con-ditions include a combination of actinic radiation and thermal heating.

19. A method as defined in claim 15, wherein said second layer is formed on the surface of said first layer.

20. A method as defined in claim 19, wherein said first layer is gelled or firmed prior to the formation of said second layer on its surface.

21. A method as defined in claim 20, wherein said first layer is gelled or firmed at an elevated temperature in the range of from about 240° F. to about 430° F., which temperature is insufficient to drive off said organic unsaturated chemical compound from said first layer.

22. A method as defined in claim 15, wherein said polythiol is pentaerythritol tetrathioglycolate.

23. A method as defined in claim 15, wherein said polythiol is trimethylol propane trithioglycolate.

24. A method as defined in claim 15, wherein said polythiol is trimethylol ethane trithioglycolate.

25. A method as defined in claim 15, wherein said polythiol is polyethylene glycol dimercaptoacetate.