Patented Apr. 27, 1937

2,078,881 . . . . . PROCESs FoR coATING RUBBER AND PRODUCT Walter M. Minzinger, Heidelberg-Rohrbach, Germany,

assignor to Röhm & Haas Com pany, Philadelphia, Pa...... pDrawing. Application March 22, 1934, serial No. 716,903. In Germany March 20, 1933

. . . .'' 9 Claims. : (CI. 91-68) This invention relates to method for apply terials or proportions set forth since other poly ing a coating to rubber surfaces for protective or merizable materials may be used, and the rubber ... decorative purposes. may also be in the form of an artificial or vulcan

Quick drying lacquers have: been satisfac ized latex. - . . . . . 5 tory because after drying they ally do not ad Eacample 1-A rubber surface is first coated 5 here well to the rubber surface. Slow drying oil with an emulsion made up of equal volumes of coatings have been used, but are uneconomicaluneconc concentrated latex (75% dry rubber) and an because of the long time required for the coating aqueous dispersion containing 25% of polymer to dry thoroughly. Many methods have been ized ethyl methacrylate. This coating is allowed suggested, but up to the present these have not to dry for about five minutes at about 25 C. and 0 proved satisfactory. a finishing coat consisting of a 25% aqueous It has now been found that if the rubber sur emulsion of polymerized methyl acrylate is ap face is first coated. With a layer of material which plied. An extremely lustrous finish is obtained has the property of adhering firmly to the rubber and the coatings adhere very firmly to the rubber on the one side and to a lacquer coating on the surface. other, a perfectly satisfactory result is obtained. Plasticizers such as the esters of phthalic acid, 15. Solutions of rubber and polymers of unsaturated etc. may be added to the erhulsion for the ground Organic compounds have been Suggested for this coat, and also to the finishing coat. purpose, but the desired result was not achieved. Eacample 2-A rubberized fabric is coated with However, if the ground coat is made in a special an aqueous emulsion of latex and a polymerized Way, it Will adhere firmly to the rubber and also ester of methacrylic acid containing a plasticizer 20 to any lacquer which may subsequently be ap and after drying is coated with a suitable lacquer. plied. An aqueous emulsion containing rubber Eacample 3. A rubber ball or glove is dipped and one or more polymerized unsaturated or in an aqueous emulsion of latex and a polymer ganic compounds has been found very satisfac ized ester of acrylic acid containing a plasticizer tory. The rubber emulsion is preferably the and after drying is coated with a suitable lacquer. natural latex, and the polymerized material is Eacample 4-A rubberized fabric is sprayed with preferably made by suspending the monomeric a benzol solution of a polymerized ester of meth material in Water, and subjecting it to polymer acrylic acid and after drying is coated with a suit izing influences. The polymerizable materials able lacquer. which are best suited for this purpose are the Eacample 5-A rubber article is dipped in an 30 esters, nitriles, amides, chlorides and anhydrides aqueous suspension of polymerized vinyl acetate of acrylic and alpha methacrylic acid, and also and after drying a suitable lacquer is applied. vinyl acetate. Such materials yield polymers In place of the ethyl methacrylate and methyl 35 which are more or less extensible like rubber and acrylate and other compounds mentioned in the which have the property, especially when emulsi above examples, other esters of these acids such fied in water and mixed with latex, of adhering as the propyl, butyl, amyl, phenyl, benzyl, etc., firmly to rubber surfaces. may be used and the corresponding acid amides, For certain effects, coloring matter, pigments, nitriles, chlorides, or anhydrides, and vinyl ace 40 fillers and plasticizers may be added to the tate may be applied. emulsion. The proportions of latex and polymeric material 40 The polymeric materials may be made from may be varied within a wide range in Order to only one polymerizable compound, or two or more obtain the most satisfactory finish on any partic such compounds can be polymerized jointly. ular rubber surface, Furthermore, mixtures of the finished polymers This process of coating rubber surfaces is ap 45 may also be used. plicable in the manufacture of shoes, gloves, The coating may be applied in any way such balls, artificial leather, rubberized fabrics of all as by dipping, brushing, or spraying, and the fin sorts, galoshes, etc. ishing lacquer may be applied in a similar Any suitable lacquer may be used for the fin hanner. ishing coat, but it has been found that aqueous 50 Any rubber surface, whether vulcanized or not, emulsions or solutions inorganic solvents of the N can be coated in this way and finished by apply polymerized esters, amides, nitriles, chlorides, etc., ling a coat of a lacquer to the object. of acrylic and methacrylic acid give excellent The following examples will illustrate the in coatings having a permanent high gloss. 55 vention, but this is not limited by the actual ma Although ordinarily dispersions and emulsions 55

9,078,881 give the most satisfactory results, solutions can rubber article a ground coat comprising rubber be employed in some cases. The solvent can or and the polymerization product of ethyl acrylate. dinarily be any of the well known organic sol 4. In the process of coating extensible rubber vents, such as ethylene dichloride, etc. articles the step which comprises applying to the 5 Instead of coating the rubber as above de rubber article a ground coat comprising rubber 5 scribed, a preformed film can be applied to the and the polymerization product of ethyl acrylate rubber surface if desired. and subsequently applying a finishing coat com What I claim is:- prising an aqueous dispersion of methyl acrylate. 1. In the process of producing protective or . 5. In the process of coating extensible rubber 10 decorative coatings on rubber articles the step articles the step comprising applying to the rubber O which comprises applying to the rubber article a article a ground coat comprising an aqueous dis ground coat comprising an aqueous dispersion of persion of polymerized ethyl or methacrylate to the polymerization product of a vinyl compound. which natural rubber latex has been added. which is one of the group consisting of vinyl ace 6. In the process of coating extensible rubber 5tate, the nitriles, chlorides, amides, anhydrides articles the step comprising applying to the rubber and esters of acrylic and a methacrylic acids and article a ground coat comprising an aqueous dis mixtures thereof to which natural rubber latex persion of polymerized ethyl or methacrylate to has been added, drying and subsequently apply which natural rubber latex has been added, dry ing a finishing lacquer coat. ing and applying a finishing coat comprising an 20 2. In the process of producing protective or aqueous dispersion of methyl acrylate. 20 decorative coatings on extensible rubber articles 7. A ribber article carrying a coating compo the step which comprises applying to the rubber sition comprising rubber and the polymerization article a ground coat comprising an aqueous dis product of ethyl acrylate. persion of a joint polymer of at least two vinyl 8. A rubber article carrying a coating composi 25 compounds which are members of the group tion comprising rubber and the polymerization consisting of vinyl acetate, the nitriles, chlorides, product of ethyl or methacrylate. amides, anhydrides and esters of acrylic and a 9. A rubber article carrying a ground coat com methacrylic acids to which natural rubber latex prising rubber and the polymerization product of has been added, drying and subsequently apply ethyl a methacrylate and a finishing coat com 30 ing a finishing lacquer coat. . prising ethyl acrylate. 3. In the process of coating extensible rubber articles the step which comprises applying to the WALTER M. MUNZINGEF,