CA1293436C

CA1293436C - Stain and scratch resistant resilient surface coverings

Info

Publication number: CA1293436C
Application number: CA 514552
Authority: CA
Inventors: Jack Henry Witman
Original assignee: Armstrong World Industries Inc
Current assignee: Armstrong World Industries Inc
Priority date: 1985-11-01
Filing date: 1986-07-24
Publication date: 1991-12-24
Anticipated expiration: 2008-12-24
Also published as: FR2608645B2; IT8621858A1; NL185024B; AU593159B2; NL185024C; FR2589493B1; US4935286A; JPS62108049A; BE905681A; IT1197308B; LU86635A1; NL8602708A; DE3636670A1; GB2182337A; SE8604663D0; CH672522A5; FR2589493A1; JPH0579032B2; AU581791B2; GB2182337B

Abstract

STAIN AND SCRATCH RESISTANT RESILIENT SURFACE COVERINGS

Abstract The present invention relates to surface coverings, and in particular to floor coverings, which comprise treated polyurethane or other wear layers. A
coating comprising a melamine aminoplast which preferably is at least partially etherified with alkyl groups comprising 4 to 10 carbon atoms, a vinyl modifier resin, a polyol, and an acid catalyst is formed on a release surface and thermally cured. A crosslinkable wear layer composition is then cast on the cured layer and crosslinked, and the composite is transferred to a support surface. Surface coverings are produced which exhibit surprising resistance to common household stains, and also improved scratch resistance.

Description

1~ ~1 3 ~ 3 ~

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;

STAIN AND SCRATCH RESISTANT RESILIE:NT S[~RFACE COVERINGS

- The present invention relates to surface ~k coverings, and more particularly to surface coverings which have improved scratch and stain resistance.
B _ ground of the Invention Resilient surface coverings, and ln particular resilient floor coverings, are well known in the art.
The floor coverings which are in wide use today are primarily of vinyl construction and, although they can be constructed to have varying degrees of flexibility, ~e~-they are "resilient" when compared to conventional natural materials, such as ceramic tile. A variety of such products is commercially available and these products have proved to exhibit good wear resistance;
` however, such coverings are not without certain deficiencies. For example, although vinyl flooring products have proved to be durable and stain resistant, they nevertheless tend to lose their glossy appearance through wear. A high-gloss appearance for a floor covering is often desired. Accordingly, the manufacturers of such materials have long sought to find improved floor coverings which exhibit good gloss retention.
One method of providing improved gloss ~ retention is through the application of polyurethane or - other wear layers to vinyl flooring structures. Such materials are durable and relatively scratch resistant, ' 35~ ' ' - 2 - LE~-76~6 and they tend to retain their high-gloss appearance over a longer period of time than do vinyl-surfaced flooring structures. Nevertheless, these wear layers, and in particular polyurethane wear layers, also have certain drawbacks. For example, they are susceptible to staining; thus, when exposed to common household items likely to cause stains (such as ballpoint pen, lipstick, mustard, shoe polish and the like), polyurethane coat-ings tend to be more easily stained than vinyl coatings.
In recent years, the eoatings industry has expended considerable effor~ to develop new and different types of melamine-formaldehyde resins, often referred to as aminoplasts. Such materials are melamines ~triaminotriazines) which have been N-alkylated with formaldehyde to ~rovide a methylolated or partially methylolated melamine. The methylol groups are then etherified or partially etherified to provide a crosslinkable material. Such materials have found wide use in coatings for automobiles, appliances and other fairly rigid types of surfaces, and they have also been used in coatings for certain 1exible substrates including paper, paperboard, metal foils,"eellophanes and the like. However, such materials have never been successfully applied to flooring structures, and in particular to vinyl flooring structures or to vinyl flooring structures comprising poly~rethane wear layers.
Accordingly, one objective of the present invention is to provide resilient surface coverings with protective coatings 0.2 or more mils thick which will deform in conjunction with the surface coverings, yet will provide improved scratch and stain resistance.
Another objective of the yresent invention is to provide flooring structures comprising composite wear surfaces whereby the wear layer material is provided with an improved scratch and stain-resistant charac~er.
These and other advantages of the present invention will become apparent from the detailed description of preferred embodiments which follows.

* Trademark for a brand of regenerated cellulose film produced from viscose by treatment with sulfuric acid and/or ammonium salts.

t3~3~;
_ 3 - LF~-7606 Summary of the Invention The present invention relates to surface coverings, and in particular to floor coverings, which comprise treated polyurethane or other wear layers. A
coating comprising a melamine aminoplast which preferably is at least partially etherified with alkyl '--groups comprising 4 to 10 car~on atoms, a vinyl modifier resin, a polyol, and an acid catalyst is formed on a release surface and thermally cured. A crosslinkable ~;10 wear layer composition is then cast on the cured layer and crosslinked, and the composite is transferred to a support surface. Surface coverings are produced which exhibit surprisinq resistance to common ho~sehold stains, and also improved scratch resistance.
Detailed Deseription of Preferred Embodiments In one embodiment, the present invention relates to a resilient surface covering, said covering comprising a resilient support and a crosslinked wear layer adhered thereto, the upper surface of said wear layer comprisin~ a protective eoating derived from a composition comprising (1) a melamine aminoplast which is alkyl etherified with alkyl groups eomprising 1 to 1O ~-carbon atoms, (2) a vinyl modifier resin, (3~ a polyolt and (4) a suitable catalyst, said protective coating having the ability to conform to the deflections of said wear layer, yet having improved seratch and stain resistance relative to the untreated wear layer.
In a second embodiment~ the present invention relates to a proeess for providing a wear surface for a resilient surface covering, said process comprising the steps of providing a release carrier comprising a support surface and a release coating; disposing on said ~ release coating a composition comprising (1) a melamine ;; aminoplast which is alkyl etherified with alkyl groups comprising 1 to 10 carbon atoms, ~2) a vinyl modifier resin, (3) a polyol, and (4) a suitable catalyst; at least partially thermally curing said composition;
disposing a erosslinkable wear layer composition on said 34~36 - 4 - L~1-7606 aminoplast layer, curing said wear layer; laminating said cured wear layer to a resilient support structure;
and separating said release carrier from said wear layer, whereby said surface covering comprises a wear layer having a protective coating, said protective coating being flexible, and scratch and stain-resistant r,~-, relative to the untreated wear layer.
The resilient surface coverinc3s which may be prepared according to the present invention are related to those which are presently well-known in the art.
Thus, they may comprise an underlying resilient support typical of those used to prepare vinyl flooring struc-tures. Supports of this type r,lay be derived from back~
ing materials, plastisols, foamed plastisols, randomly dispersed vinyl particles, stencil disposed vinyl particles, and the like, the selection oE such materials being well within the skill of an ordinary artisan.
The surface coverings will also comprise composite wear layer compositions. The maior portion of the wear layer will comprise materials which are presently well known in the art. Examples of such,~
materials are crosslinked wear layers derived from urethanes, acrylated or methacrylated urethanes, unsaturated polyesters, and the like, all of which are ~-well known in the art. These wear layers must be crosslinkable by moisture-curing techniques, thermally induced free radical curing techniques, oxidative curing techniques, radiation-curing techni~ues, or a combination thereof.
The novelty of the present invention resides in the presence of a second protective layer on the conventional wear layer components. This second material is derived from melamine-formaldehyde derivatives, a polyol, an acid catalyst and a vinyl modifier resin, and provides a flexible, yet scratch and stain-resistant upper surface.
The melamine-formaldehyde resins which may be used to practice the present invention are referred to 12~3~3~ ~

herein as "melamine aminoplasts." These materials may be partially or substantially methylolated, and the ~ethylol groups may ~e partially or substantially etherified with methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups, isomers of these moieties, and mixtures thereof; however, the aminoplast preferably will be at least partially etherified with a relatively long chain alkyl group having from about 4 to about 10 carbon atoms. These long-chain portions of the aminoplast assist in pro-viding flexibility to the cured vinyl ~roduct. ~any of these aminoplasts are commercially available and are sold, for example, as Cymel cross linking agents by American Cyanamid Company and as"~esimene~resins by ~lonsanto Company.
The modifier resins which will be utilized will be one of, or a combination of, resins which are well-known in the art. Examples of such resins are co-polymer solution vinyl resins derived from vinyl chloride and vinyl acetate. Resins of this type are sold by Union Carbide, and they may or may not contain hydroxyl or other functionality. Examples of other resins are specialty resins such as the polyvinyl acetals te.9-, polyvinylbutyral), either alone or in combination with polyvinyl alcohol and/or polyvinyl acetate, and polyvinyl esters such as polyvinyl acetate.
Such materials are well-known in the art as being amenable to application from solution; thus, they are distinguishable from dispersion grade and general ~urpose resins which are essentially insoluble in most conventional solvents. In essence, the modifier resins should be suitable to enhance the flexibility and strength of the cured composition Jithout adversely affecting the stain resistance.
; 35 The polyols which may be used to practice the ~resent invention are alcohols ~hich comprise two or more alcohol groups. For example, 1,6-hexanediol, 1,4-cyclohexane dimethanol, glycerine, neopentyl glycol, * Trademark ** , `~ - 6 - 1 ~c~3 4 3~ LFM-76U6 tripropylene glycol, 1,4-butanediol, trimethylolpropane, pentaerythritol, and many other polyols may be utilized to practice the present invention, said polyols being well-known in the art.
The acid catalysts which may be used to catalyze the thermal curing reaction between the vinyl modifier resin, the melamine aminoplast, the polyol and the wear layer surface are also well-known in the art.
Examples of such catalysts are sulfonic acids, such as methanesulfonic acid and p-toluenesulfonic acid, and other acids such as citric acid, maleic acid, phthalic acid, etc. The catalysts may be used in the free acid form, but they may also be stabilized, such as by the p-~
use of an amine to neutralize the acid. Examples of such amines are ammonia, diisopropanol amine, and 2-amino-2-methyl-1-propanol. The only restriction is that the catalysts must be compatible with the other components of the system. Because these catalysts are all well-known by those skilled in the art, their selection will be within the capability of an ordinary artisan. ~
To practice the present invention, a release ' surface is provided for the aminoplast composition. For a very smooth surface, a polished chrome plate or a release paper coated with a polyalkylene material can be used, a particularly ~ood example of the latter being polypropylene. For less glossy surfaces, other types of coated papers or belts may be used, examples of which are silicone-, comple~ed chromium- and methyl cellulose-treated papers or belts. The selection of suchmaterials i~s well within the skill of an ordinary artisan.
Onto the release paper is cast a layer of aminoplast composition. Although the component ratios of the composition will have substantial variability, the composition will usually comprise from about 4 to 1 parts of modifier resin for every 1 to 4 parts of the aminoplast/polyol mixture. Further, the aminoplast/

7 ~ 36 LFM-76U~

~olyol mixture may comprise from about 5 to 1 parts of aminoplast for every 1 to 5 parts of polyol. Prefeeably, however, there will be from abo~t 3.5 to 1 parts of modifier for every 1 to 2 parts of aminoplast/polyl having a ratio of from about 3 to 1 parts of aminoplast for every 1 to 3 parts of polyol. Usually this composition will be provided in an organic solvent;
however, it is also possible to apply the composition in aqueous form.
After the aminoplast composition is applied to the release paper, it is dried and at least partially cured at about 250~F. Although it is possible to form the laminates of the present invention using partially cured aminoplast layers, to obtain a high quality 15 product it is usually preferable to ensure that the aminoplast layer is fully cured prior to the ~eposition of the urethane layer.
The crosslinkable wear layer coa~ing composition may be disposed directly on the aminoplast 20 layer after the aminoplast layer is cured. It is noted, however, that the artisan may optionally elect to pre-treat ~he surface of the cured aminoplast layer by corona discharge or by applying a key coat composition so as to promote adhesion between the layers. The 25 latter com~ositions, which typically are vinyl lacquers, J
are in wide use and are well-known to those skilled in the art. Such compositions often comprise vinyl chloride copolymer solution resins such as the VAGH
resin described above.
Corona discharge is also well-known in the art and involves a raising of the surface energy by exposing the surface to an electrical arc. The amount of energy necessary to promote good adhesion may be readily determined by standard means. Thus, the surface tension of the coating composition may be determined according to ASTI~ ~ 1331 and the surface energy of the surface to be coated may be determined essentially as described in ASTM D 2578. The objec~ive is to raise the surface 3~

energy of the surface to be coated such that it will be wetted by the coating composition. Ideally the surface energy resulting from the corona treatment will be at least about 10 dynes/cm greater than the surface tension of ~he coating composition.
The thickness of application of the ~ear layer composition can vary from about 1 to about 8 mils, but preferably will vary from about 2.5 to about 4.5 mils.
The composition may be a low solids ~e.g. 40~) solution of polyether or polyester-based urethane which is moisture curable, or it may com~rise a 2-component system SUC}I as a polyester comprising hydroxyl functionality combined with a diisocyanate. Curing of the latter composition occurs by reaction of the diisocyanate with the hydroxyl groups of the ~olyester, as well as with moisture in the air. Alternatively, radiation curable, F combined radiation and moisture curable, components can be utiliæed. As with the aminoplast layers, it is also advisable to ensure that the urethane layer is fully cured before lamination to the resilient surface covering is achieved.
hhen fully cured materials are pre~ared and then laminated to resilient surface coveringsl occasional poor adherence of the laminate to the surface covering has been encountered. As with the aminoplast layer and wear layer, it has been found desirable to avoid delamination problems by providing a key coat between the back (exposed) surface o~ the wear layer and the resilient layer with which it is interfaced. As an alternative, corona discharge treatment is also available to facilitate adhesion of the coats.
The upward facing wear layer is interfaced wi~h the resilient support surface layer, with or without an intervening key coat or corona discharge treatment, and the composite material is subjected to heat and pressure to ensure firm adhesion. The composite material may also be afixed to granular or consolidated stencil vinyl products in the same manner.

- g - LF~-7606 3~36 After consolidation is com~lete, the release paper is stripped from the hot sample to provide a decorative surface covering which exhibits good scratch and stain resistance. Thus, the materials are resistant to staining by household items such as lipstick, mustard, shoe polish, food dye and the like.
The present invention will be better understood by reference to the examples which follow, said examples being provided by way of illustration and : 10 not limitation.

EXAMPL~S
Example_l The followin~ compositions are prepared comprising each of the indicated components in parts by weight:

Sample No.

Component 1~ 2 1-3 1-4 1-5 Xylol 31.031.2 31.222.9 31.3 ~.
Vinyl chloride/vinyl acetate copolymer (VAGH from Union Carbide) - 13.6 13.613.6 19.3 UV stabilizer (Vvitex 0~, 1~ in xylol) 1.01.0 1.01.0 1.0 Organotin stabilizer ('~hermolite 31"~rom Metal and Thermit Co.) - 0.250.25 0.25 0.3$ L
Fluorocarbon surfactant (E~C-430 from 3-~ Company;
10~ in xylol) 1.00.8 0.80.76 0.8 ~iethyl isobutyl ketone 35.0 40.10 38.40 34.00* 55.50 Diacetone alcohol 8.08.0 8.014.0 8.~
Isopropyl alcohol 3.63.6 3.6 - 3.5 Aminoplast resin (Resimene 755"~rom ~onsanto)15.35.1 - 20.4 4.13 ;.
: 1. Trademark of Ciba-Geigy Corporation 2. Trademark 3. Trademark 4. Trademark ;

4~k:
-- Sample No.
__~ __ Component (cont'd.) 1~ 2 1-3 1-4 1-5 Cyclohexane dimethanol ~90% in water) 5.1 1.7 - 6.~ 1.38 5 Aminoplast resin (~ymel 301*~ :
from American Cyanamid) - - 5.1 - -1,6-Hexanediol - - 1.7 p-Toluenesulfonic acid (25%
in 1:1 xylol/isopropyl 10alcohol) 2.90.9 0.9 30~ 0.8 Viscosity, ~2 Zahn cup (seconds) 15 ~3 30 30 35 Total Solids (%) 20.619.7 19.8 35.9 20.3 Ratio of vinyl copolymer to 15total melamine plus diol - 2:1 2:1 1:2 3.5:1 *Methyl ethyl ketone may be substituted for methyl ~-isobutyl ketone Each of a series of polypropylene-coated release papers is provided with a coating of one of the above compositions at a thickness of about 2.5 to 3.5 mils wet using a reverse roll coater. l'he coated paper is then passed through a ~50F oven such tl~at the coating resides in the oven for 4 minutes.
A moisture-curable polyurethane coating composition is prepared for application to the coated release papers. The components are as follows:

Component Weight (Grams?
; Polyetherdiol (Union Carbide"LHT 240~1) 40.80 Polyetherdiol (Union Carbide"L~T 112~ ) - 14.~0 Xylene solvent 110.00 ~oluene solvent 46.00 *~ Trademark 1. Trademark 2. Trademark '' 3~3~i .

Component (cont'd.) Weight (Grams) Dimethyltin dineodecanoate catalyst (~itco UL-28'~* 0.55 Surfactant ~'Monsanto XA-677 Multiflow'~ 0.30 5 Light stabilizer (American Cyanamid UV-5411)*** ~o20 These components are charged to a stirred, nitrogen-purged glass reactor and heated to 70C for one hour. A 44.90-gram quantity of 4,4'-diisocyanato dicyclohexylme~ne is added dropwise over a 30-minute ; period of time at a rate sufficient to maintain the temperature of the mixture at 70C. After an additional two-ho~r period of stirring and heating at 70C, the product is cooled.
To each of the release ~apers is applied a 1-to 2.5-mil wet layer of key coat lacquer comprising 18.54 ~ercent by weight of VAGH resin, 0.37 percent "Thermolite 31', 0.0094 percent Uvitex OB and 81.08 percent methyl isobutyl ketone solvent. The coated sample is then dried in ambient air or under low heat to remove the solvent. Upon completion of the drying step, each paper is provided with a 5- to 6.5-mil wet coating of the moisture curable polyurethane material described above. The coated samples are then passed through a 250F oven to completely dry the sample, the dwell time in the oven being 7 minutes.
The lamination and consolidation steps involve the use of a 12 inch x 12 inch press to prepare 9 inch x 9 inch samples. The top platen of the press is heated at 310F whereas the bottom platen is heated at 300F. The dwell time in the press is 10 seconds at 250 pounds pressure, followed by 10 seconds at 1200 pounds of pressure. Following removal of the sa~ple from the press, the release paper is stripped from the hot sample.
Both stencil vinyl and gelled vinyl plastisol resilient support materials may be used for lamination with the above coa~ings, and stain resistance can be * Trademark ** ..
*** ~

12 1~3~36 LF~ 7606 evaluated using ordinary household stains. All samples show superior stain resistance as compared to the untreated polyurethane material, and also show good scratch resistance~
~xample 2 Two coating compositions having the compositions set forth for sample 1-2 and 1-4 are prepared and each coating is a~plied to a poly~ropylene surface release paper using a forward roll coater. ~ach release paper is passed twice through the coater in order to obtain a total dry film thickness of 0.25 mils.
Curing is obtained by passing the coated sheets through a 250-260 F oven at a dwell time of 1.5 minutes for each coating. Two rolls of paper are prepared, each being provided with one of the two coatings.
Each of the rolls is treated such that one-half of each is coated with the vinyl key coat composition described in Example 1 and the other half is treated with corona discharge. The key coated portions of the roll are provided as described in Example 1, the drying of the coating being accomplished in an oven at a dwell time of less than one minute. I~he corona discharge exposure for the remaining portions of the rolls is 9.1 watts/square foot/minute sucl~ that the surface energy is about 55 dynes/cm.
Following the application of the key coat and the corona treatment, all rolls are coated with a 3.2-mil wet thickness of the polyurethane coating described in Example 1 and the coating is cured as described in that example. The entire surface of each roll is then provided with a vinyl key coat as described above and the coated material is interfaced with a granular stencil vinyl mix. Consolidation is achieved as described in Exa~ple 1. The resulting products demonstrate good stain and scratch resistance and the coating is firmly adhered to the substrate.

- 13 ~ 3~3~ LF~ 7606 Example 3 (~oating compositions are prepared having the following components.

5 Sample No.
Component 3-1 3-2 3-3 3-4 3-5 ,-Toluene 28.1028.10 28.1023.6029~05 Butyl acetate 42.1442.14 42.143~.9343.54 Xsopropyl alcohol 6.32 6.32 6.325.34 6.56 10Organotin stabilizer (Thermolite 31) 0.21 0.21 t).210.210.;~7 Vinyl chloride/vinyl acetate copolymer (VAGH) 14.4614.46 14.4611.1514.74 UV stabilizer (Uvitex OB)1.06 1.061.06 1.67 1.12 15Fluorocarbon surfactant ( FC-430) 0.50 0.50 0.500.77 0.53 Aminoplast resin Resimene 755 5.40 - - 16.72 3.16 Cymel 1130 ( f rom Cyanamid) - - 5.4 Cymel 1133 (from Cyanamid) - 5.40 - - -Cyclohexane dimethanol (90% in water) 1.81 1.81 1.815.57 1.05 p-Toluenesulfonic acid (25~ in 1:1 xylol/
isopropyl alcohol)0.250.25 0.250.78 0.15 ;~

Total Solids (%)21.67 21.6721.6733.44 19.20 i Ratio of vinyl copolymer to total melamine plus diol 2:1 2:1 2:1 1:2 3.5:1 Three sets of samples are prepared following the procedure of Example 1, but using each of the above five coatings. One set of samples is provided wherein 3 5 the cured coating on a release paper is corona treated prior to coating with the polyurethane layer of Example l;
a second structure is provided wherein a key coat of Example 1 is used between the cured coating on the 3~3~

release paper and the polyurethane layer; and a third set of samples is prepared wherein neither a key coat nor a corona treatment is used between the melamine-containing layer and the polyurethane layer.
S In all cases, excellent stain resistance is noted and in essentially all instances, firm adhesion o~ the melamine-containing layer to the polyurethane layer is obtained.
The present invention is not restricted solely 10 to the descriptions and illustrations provided above, ~-but encompasses all modifications envisaged by the following claims.
~.

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Claims

1. A surface covering comprising a resilient support and a crosslinked wear layer adhered thereto, the upper portion of the wear layer being formed from a composition comprising (a) an aminoplast, (b) a vinyl chloride copolymer resin, (c) a polyol, (d) a catalyst, and (e) a solvent, the solvent comprising at least 64% by weight of the composition.

2. The surface covering of claim 1 wherein the aminoplast is a melamine aminoplast.

3. The surface covering of claim 1 wherein the aminoplast is a melamine aminoplast.

4. The surface covering of claim 1 wherein the aminoplast is a urea resin.

5. The surface covering of claim 1 in which the crosslinked wear layer is a composition, the lower portion of the war layer disposed between the upper portion of the wear layer and the resilient support is derived form materials selected from the group consisting of urethanes, acrylated urethanes, methacrylated urethanes and unsaturated polyesters.

6. The surface coating of claim 1 wherein the vinyl chloride copolymers resin is a copolymer of vinyl chloride and vinyl acetate.

7. A surface covering comprising a resilient support and a crosslinked were layer adhered thereto, the upper portion of the wear layer being the reaction product of a composition consisting essentially of (a) an aminoplast, (b) a vinyl chloride copolymer resin, and (c) a polyol.

8. A composition comprising a substantially unreacted aminoplast, a substantially unreacted polyol and a vinyl chloride copolymer resin.

9. The composition of claim 8 wherein the aminoplast is a urea.

10. The composition of claim 8 wherein the aminoplast is a melamine.

11. The composition of claim 10 wherein the melamine is alkyl etherified with alkyl groups comprising 1 to 4 carbon atoms.

12. The composition of claim 8 wherein the vinyl chloride copolymer resin is a copolymer of vinyl chloride and vinyl acetate.

13. The reaction product of claim 8.

14. A protective coating comprising the reaction product of claim 13.

15. A process for providing a wear surface for a resilient surface covering comprising providing a release carrier comprising a support surface an a release coating, disposing on release coating a composition comprising (a) an unreacted aminoplast (b) a vinyl chloride copolymer resin, (c) a substantially unreacted polyol, and (d) a suitable catalyst, at least partially thermally curing the composition, disposing a crosslinkable wear layer composition on the aminoplast layer, curing the wear layer, laminating the cured wear layer to a resilient support structure, and separating the release carrier from the wear layer.

16. The process of claim 15 wherein the aminoplast is urea based.

17. The process of claim 15 wherein the aminoplast is a melamine which is alkyl etherified with alkyl groups comprising 1 to 4 carbon atoms.

18. The process as set forth in claim 15 wherein the wear layer is derived from material selected from the group consisting of urethanes, acrylated urethanes, methacrylated urethanes, and unsaturated polyesters.

19. The process as set forth in claim 15 wherein the vinyl chloride copolymer resin is a copolymer of vinyl chloride and vinyl acetate.