Vinyl Chloride Polymer Laminate

This invention relates to vinyl chloride polymer laminates and unsupported films having improved stain resistance.

An object of this invention is to provide a vinyl chloride polymer laminate and unsupported film having improved stain resistance.

Another object of this invention is to provide a method for making a vinyl chloride polymer laminate and unsupported film having improved stain resistance.

These and other objects and advantages of the present invention will become more apparent to those skilled in the art from the following detailed description and accompanying drawing which is a flow chart showing methods for making a stain resistant vinyl chloride polymer (PVC) laminate or unsupported film.

According to the present invention a layer of a flexible vinyl chloride polymer is coated with a catalyzed reactive polyester-amino resin composition in solvent and heated to cure and adhere the resin to the vinyl chloride polymer layer with removal of the solvent to provide the flexible vinyl chloride polymer layer with a coating which is stain resistant or which can readily be cleaned to remove stains.

As shown in the accompanying drawing which represents embodiments of the present invention a vinyl chloride polymer plastisol is coated and fused or a plasticized vinyl chloride polymer composition is calendered or extruded. They may be applied to a substrate or support. In either case the vinyl chloride polymer layer (about 1 to 30 mils thick) can be printed one or more times. Then the printed layer is embossed, optionally printed again, and finally coated with a layer of a solution of a reactive polyester-amino resin composition and cured to provide the vinyl chloride polymer layer with an outer stain resistant layer about 0.1 to 2 mils thick.

The FIGURE shows a block diagram of the process of the invention.

The vinyl chloride polymer can be an emulsion (plastisol grade) or a suspension grade vinyl chloride polymer. The vinyl chloride polymer can be homopolyvinyl chloride (preferred) or a copolymer of a major amount by weight of vinyl chloride and a minor amount by weight of a copolymerizable monomer selected from the group consisting of vinyl acetate, vinylidene chloride and maleic ester. Bulk and solution vinyl chloride polymers, also, may be used. Mixtures of vinyl chloride polymers can be used. Vinyl chloride polymers and copolymers are well known. In this connection please see "Vinyl and Related Polymers," Schildknecht, John Wiley & Sons, Inc., New York, 1952; Sarvetnick, "Polyvinyl Chloride," Van Nostrand Reinhold Company, New York, 1969; Sarvetnick, "Plastisols And Organosols," Van Nostrand Reinhold Company, New York, 1972 and "Modern Plastics Encyclopedia 1980-1981," October, 1980, Volume 57, No. 10A, McGraw-Hill Inc., New York.

The amount of plasticizer used to plasticize the vinyl chloride polymer to make it flexible may vary from 30 to 100 parts by weight per 100 parts by weight of total vinyl chloride polymer resin. Examples of plasticizers which may be used are butyl octyl phthalate, dioctyl phthalate, hexyl decyl phthalate, dihexyl phthalate, diisooctyl phthalate, dicapryl phthalate, di-n-hexyl azelate, diisononyl phthalate, dioctyl adipate, dioctyl sebacate, trioctyl trimellitate, triisooctyl trimellitate, triisononyl trimellitate, isodecyl diphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, polymeric plasticizers, epoxidized soybean oil, octyl epoxy tallate, isooctyl epoxy tallate and so forth. Mixtures of plasticizers may be used.

Other vinyl chloride polymer compounding ingredients are desirably incorporated in the vinyl chloride polymer compositions. Examples of such ingredients are the silicas such as precipitated silica, fumed colloidal silica, calcium silicate and the like, calcium carbonate, ultra violet light absorbers, fungicides, carbon black, barytes, barium-cadmium-zinc stabilizers, barium-cadmium stabilizers, tin stabilizers, dibasic lead phosphite, Sb.sub.2 O.sub.3, zinc borate and so forth and mixtures of the same. TiO.sub.2, red iron oxide, phthalocyanine blue or green or other color pigments can be used. The pigments and the other dry additives preferably are dispersed or dissolved in one or more plasticizers before adding to the plasticized vinyl chloride polymer compositions. These compounding ingredients are used in effective amounts by weight to control color, mildew, stabilization, viscosity and so forth of the plasticized vinyl chloride polymer.

The vinyl chloride polymer composition may contain suitable blowing or foaming agents such as sodium bicarbonate, and the organic agents like 1,1'-azobisformamide, 4,4'-oxybis(benzene sulfonylhydrazide), p-toluenesulfonyl hydrazide and so forth to form a cellular or foamed vinyl chloride polymer composition layer or sheet on fusing. The blowing agents may require an activator. Such blowing agents are well known.

Vinyl chloride polymer blending or extender resins, also, can be used in the compositions in a minor amount by weight as compared to the vinyl chloride polymer composition.

The ingredients forming the vinyl chloride polymer composition may be charged to and mixed together in any one of several mixing devices such as a Ross Planetary mixer, Hobart dough type mixer, Banbury, 2-roll rubber mill, Nauta mixer and ribbon blender and so forth.

The vinyl chloride polymer composition can be formed into layers or films which can be unsupported or supported (preferred). Where a vinyl chloride polymer plastisol composition is used, it may be cast on a release surface and heated to fuse it to form a film. Where a plasticized suspension grade vinyl chloride polymer composition is used, it can be calendered or extruded and fused to form a film. Temperatures may vary from about 200.degree. to 400.degree. F. However, it is preferred that in either case the compounded vinyl chloride polymer compositions be supported or have a backing. In the case of the supported vinyl chloride polymer composition, the substrate can be a woven fabric (drill, scrim, cheesecloth, and so forth), a knit fabric, a non-woven fabric, paper etc. The fabric can be made of cotton, cellulose, nylon, polyester, aramid, rayon or acrylic fibers or cords or mixtures of the same. It may be necessary in some instances to treat the fabric with an adhesive coating or dip to adhere or to adhere better the fabric to the vinyl chloride polymer composition.

The vinyl chloride polymer composition film or layer, supported or unsupported, is preferably printed on the surface of the vinyl chloride polymer with a suitable vinyl chloride polymer receptive ink to form desirable and novel patterns and designs. Such inks are well known and can be applied by various methods of printing such as by gravure, flexography, screen printing, jet printing, web printing and so forth. See "Modern Plastics Encyclopedia 1980-1981," pages 464-465. The printing operation may be repeated for up to five times or more to vary the colors and designs at temperatures of from about 150.degree. to 165.degree. F. for each printing step.

The vinyl chloride polymer composition film or layer, supported or unsupported, printed or unprinted, is preferably embossed to texture the vinyl chloride layer to provide a pattern or design for esthetic or functional purposes. Embossing of thermoplastic films, layers or sheets is well known and is usually carried out by passing the film between an embossing roll and a backup roll under controlled preheating and postcooling conditions. See "Modern Plastics Encyclopedia 1980-1981," pages 454-455. Additional decorating or printing can sometimes be done with the above stated inks over the embossed vinyl chloride polymer surface for better aesthetic purposes.

The reactive polyester-amino resin for use as the outer or top coating on the vinyl chloride polymer layer is prepared from a solution of a reactive polyester (alkyd resin) and an amino resin in an organic solvent such as methyl ethyl ketone containing a catalyst and is applied at a temperature of at least about 200.degree. F. to cause curing or crosslinking of the alkyd resin and the amino resin. The reactive polyester-amino resin solvent composition may be applied to the vinyl chloride polymer composition film directly, with or without the backing or substrate, with or without the printing steps and with or without the embossing step. It is preferred that the catalyzed reactive polyester-amino resin solution be applied to an embossed and printed compounded and plasticized vinyl chloride polymer composition carried on a suitable backing or substrate.

The polyester resins (alkyd resins) are made by a condensation polymerization reaction, usually with heat in the presence of a catalyst, of a mixture of a polybasic acid and a polyhydic alcohol. Fatty monobasic oils or fatty acids, monohydroxy alcohols and anhydrides may be present. They, also, contain active hydrogen atoms, e.g., carboxylic acid groups for reaction with the amine resin. Example of some acids to use to form the alkyd resin or reactive polyester are adipic acid, azelaic acid, sebacic acid, terephthalic acid and phthalic anhydride and so forth. Examples of some polybasic alcohols to use are ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerine, butylene glycol, 2,2-dimethyl-1,3-propanediol, trimethylol propane, 1,4-cyclohexanedimethanol, pentaerythritol, trimethylolethane and the like. Mixtures of the polyols and polycarboxylic acids can be used. Examples of a suitable reactive polyester to use is the condensation product of trimethylol propane, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, phthalic anhydride and adipic acid. Mixtures of these reactive polyester or alkyd resins can be used. Alkyd resins are well known as shown by the "Encyclopedia Of Polymer Science And Technology," Vol. 1, 1964, John Wiley & Sons, Inc., pages 663-734; "Alkyd Resins," Martens, Reinhold Publishing Corporation, New York, 1961 and "Alkyd Resin Technology," Patton, Interscience Publishers, a division of John Wiley and Sons, New York, 1962. Some unsaturated polybasic acids and unsaturated polyols may be used in the condensation reaction but are generally undesirable. The reactive polyester or alkyd resin is usually added to the amino resin while dissolved or suspended in an organic solvent such as a mixture of a ketone and an alkyl acetate at about 60-80% solids.

The amino resin to be reacted with the reactive polyester is an alkylated benzoguanamine-formaldehyde, alkylated urea-formaldehyde or, preferably, an alkylated melamine-formaldehyde resin. Mixtures of these resins can be used. The alcohol used to modify the benzoguanamine-formaldehyde, urea-formaldehyde or melamine-formaldehyde resin can be n-butanol, n-propanol, isopropanol, ethanol or methanol and so forth. These amino resins are well known. Please see "Aminoplastics," Vale et al, Iliffe Books Ltd., London, 1964; "Amino Resins," Blair, Reinhold Publishing Corporation, New York, 1959, "Modern Plastics Encyclopedia 1980-1981," pages 15, 16 and 25 and "Encyclopedia Of Polymer Science And Technology," John Wiley & Sons, Inc., Vol. 2, 1965, pages 1 to 94.

Sufficient amounts by weight of the reactive polyester and amino resin are employed to provide a stain resistant, cross-linked layer having good durability and flexibility and having good adhesion to the compounded and plasticized vinyl chloride polymer layer on curing and crosslinking. These materials are cured at temperatures of at least about 200.degree. F. for effective times in the presence of a minor amount by weight of an acidic catalyst like boric acid, phosphoric acid, acid sulfates, hydrochlorides, phthalic anhydride or acid, oxalic acid or its ammonium salts, sodium or barium ethyl sulfates, aromatic sulfonic acids such as p-toluene sulfonic acid (preferred) and the like. Prior to curing flatting agents or other additives can be added to the mixture of the reactive polyester and amino resin.

The stain resistant laminates of the present invention are particularly useful as wallcoverings especially for hospitals. However, these stain resistant laminates, also, can be used in the manufacture of tablecloths, shoe uppers, luggage exteriors, upholstery, vehicle interiors and seats, golf bags and other sporting goods and so forth.

The following examples will serve to illustrate the present invention with more particularity to those skilled in the art.

Homopolyvinyl chloride (PVC) containing plasticizer, stabilizer and other compounding agents was calender coated onto a cotton and polyester blend drill fabric at about 350.degree. F. to form a plasticized and compounded PVC film about 4 mils thick on the fabric backing. Next the PVC layer was printed five times with heating at about 160.degree. F. between each printing step to form a design on the surface of the PVC film. The printed film was then passed under an embossing roll and cooled to form an embossed pattern on the printed PVC film. The embossed and printed PVC film was then gravure finish roll coated with a solution of a reactive polyester (alkyd resin) containing carboxylic acid groups and an amino resin and cured at about 200.degree. F. to remove the solvent and to form a stain resistant, crosslinked and adherent layer of about 0.5 mil thick on the embossed and printed PVC layer.

The mixture of the reactive polyester and amino resin contained the following ingredients:

Test samples were cut from the laminated PVC composite, treated with staining agents and then washed to ascertain the effectiveness of the coating on rubbing with various cleaning agents. T1 TABLE 1- Number of Hand Rubs to Remove Stain? - Cleaning Agents? -Stain? A? B? C? D? -Lipstick NR 20 10 6 - Shoe Polish NR NR 10 4 - Iodine Solution #? 10 4 3 3 - Burn Cream ##? NR NR NR 10* - Coffee/Tea 15 5 4 3 - (50:50 mixture in water) - Mustard NR NR NR 10 ? - Felt Tip Pen NR NR 45 10 ? - Ball Point Pen NR NR NR 7 - Spray Paint (Enamel) NR NR 10 5 - Permanent Stencil Ink NR NR 30 6? -

The method of this example was the same as that of Example 1, above, except that the outer layer of the solution of reactive polyester and amino resin was not applied to the embossed and printed layer on the PVC backed film. The results on testing are shown in Table 2, below: