Patented Feb. 11, 1930 1,746,875 UNITED STATES PATENT OFFICE MERWYN C. TEAGUE, OF ELMHURST, NEW YORK, AssIGNOR. To AMERICAN RUBBER COMPANY, OF EAST CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF MASSACHU SETTS METHOD OF FORMING TACKY RUBBER COMPOUND AND PRODUCTS V. No Drawing. Application filed June 9, 1924. serial No. 719,017. This invention relates to a method of form gredient. The invention also comprises the ing a tacky rubber compound and to the prod products of the process. ucts formed, more particularly to a method In carrying out the invention any suitable of making such products directly from a Substance comprising an ingredient or in 5 water dispersion of rubber such as latex. gredients imparting tackiness, more particu 55 For certain purposes in the rubber art the larly a distillation residue containing heavy use of a tacky rubber compound is indicated, hydrocarbon such as pine tar, rosin, coal tar, such as when making plied goods, adhesive hardwood pitch, etc., and preferably those de cements for rubber footwear and other pur rived from ligneous matter, of an acidic char 10 poses, adhesive tape, etc. It has been known acter or containing combined acid radicals, is 60 that certain ingredients such as pine tar, first converted into an easily decomposable rosin, coal tar, hardwood pitch, and other Water soluble compound, preferably by com materials have the property of imparting bining or saponifying it with a volatile base tackiness to rubber with which they are com Such as ammonia, or with a substituted am pounded, and these materials when so used monia, such as methyl amines, ethyl amines, 65 V have been mixed with the rubber in plastic etc. By heavy hydrocarbon is meant those form on a mill in the usual manner. As such hydrocarbons high up in the various homol rubber must first be formed from latex by ogous series, that is having a relatively high 20 Some one of the usual methods of coagulat proportion of carbon, and which remain after ing or drying and then broken down on a the lower boiling fractions have been distilled O mill the process involves the expenditure of off. It is preferred to effect such combina considerable time, labor and power. Prior tion by the process disclosed in my co-pend to my invention there has been no method by ing application, Serial No. 15,407, filed March which water insoluble substances of the char 18, 1925, but the invention is of course not 'acter specified could be mixed in water soluble limited to the use of this method. By this 75 and non-coagulative form directly with latex. process rosin, pine tar, or other organic acidic An object of my invention is to provide a material is treated with concentrated aqueous. process for forming tacky rubber compounds ammonia in a closed vessel and the mixture directly from latex or other water dispersion Subjected to heat and pressure to form an of rubber. Another object is to provide a easily decomposable compound of the react 80 process for mixing with latex an ingredient ing ingredients. The amount of heat and in water soluble form for imparting tacki pressure varies with the acid value of the ness to the resulting rubber. Another object material. The result of the above-mentioned is to provide a process for making a stabilized process is to produce an ammonium or am latex for use in making a tacky rubber com monium-base compound or saponification 85 pound. A further object is to provide a product of the tackiness imparting ingredi stabilized latex embodying an ingredient. ents, which is water soluble and easily decom producing tackiness when dried. A still posable, for instance, one that will decom 40 further object is to provide an improved pose at normal room temperatures, by tacky rubber compound. A still further ob slightly heating it, or by drying. This com 90 ject is to provide a tacky dried rubber latex. pound is then, either as such or in water solu For a detailed disclosure of the nature and tion, mixed with the latex and has the prop objects of the invention reference is had to erty of stabilizing the resulting mixed latex the accompanying specification and claims. for considerable periods, such as a week or 45 The invention comprises, broadly, convert more. The latex used may be one in its 95 ing an ingredient imparting tackiness into an natural concentration or modified as circum easily-decomposable water-soluble compound, stances may require. By reason of this sta mixing such a compound with a water dis bilizing large batches of latex mixes suitably persion of rubber such as latex, and recon compounded for various purposes can be eco 'verting the compound into the original in nomically and conveniently made up in a fac 09 2 1,746,875 tory for use as needed. The stabilized latex by steam at atmospheric pressure or in any mixture is then used in any desired manner, other suitable manner. In the making of for instance as a cement for making foot some tacky rubber compounds reclaimed rub wear, etc., for making plied goods, for coat ber is used, and in this case Such rubber may ing in making such articles as adhesive tape, be formed into a water dispersion in any of 70 and in any of the other cases in which a tacky the known ways and then mixed with the rubber compound is applicable. The term tackiness imparting ingredients in the man tacky is used to indicate a sticky or adhesive ner above described, with or without the ad quality of the rubber. This quality is dition of latex. Or if desired instead of O sought in making certain rubber cements. latex there may be used a water dispersion 75 During the drying operation after use of the of coagulated rubber formed in any of the latex mixture as above described the ammonia known ways. is split off and removed, leaving the tackiness While specific examples of the invention imparting ingredient in an insoluble form have been given, with the use of specific in 5 uniformly distributed in the rubber from the gredients, it is capable of broad application, 80 latex. If desired the latex mixture contain and other materials may be substituted as ing the water soluble compound may first be long as the desired water insoluble ingredient dried in any suitable manner, thereby elimi for imparting tackiness is converted into an nating the ammonia as above described and easily decomposable water soluble compound 20 leaving a tacky rubber compound which may and then reconverted into an insoluble con 85 be used in the same manner as similar rub dition after mixture with the water dispersion ber compound mixed on a mill by the prior of rubber. It is therefore not desired to known methods. By the method above de limit the invention except as set forth in the scribed an ingredient for imparting tacki appended claims and their equivalents. 25 ness may be introduced into rubber without Having thus described my invention what 90 the necessity of mixing in on a mill and with I claim and desire to protect by Letters Pat out the introduction into the final product of ent is: a s f any unnecessary or objectionable substance. 1. The method of forming a tacky rubber The prepared mixture forms a cement which compound which comprises mixing with a 30 is not in itself tacky but assumes this condi water dispersion of rubber an easily decom tion when the base is eliminated-for ex posable water soluble compound of a water ample by driving off the ammonia by drying insoluble ingredient for imparting tackiness, at normal or elevated temperature. and decomposing said water soluble com An example of a tacky compound suitable pound and removing therefrom that portion 35 for use as a shoe cement is as follows: - rendering it soluble, whereby a tacky rubber O) 100 parts rubber by weight as latex con product is obtained. taining 33%% solids. 2. The method of forming a tacky rubber 20 parts ammonium resinate (dry basis) compound which comprises mixing a water by weight. soluble easily decomposed compound of a 280 parts water (not including that in the basic substance and an acidic tackiness im latex). parting ingredient with a water dispersion 24 parts litharge by weight. of rubber, and eliminating said basic sub 42 parts sulphur by weight. stance, whereby a tacky rubber product is ob In mixing the above compound a paste is tained. 45 made of the litharge and sulphur, by using 3. The method of forming a tacky rubber O the ammonium resinate solution, and the mix compound which comprises mixing a water ture is then added to the latex and stirred soluble easily decomposed compound of a well. Concentrated latex may be used if de volatile base and a tackiness imparting in sired, in which case the added water would gredient containing acid radicals with a SO be accordingly reduced in quantity. If a sol water dispersion of rubber, and removing. 5 vent is desired in the compound 200 parts of said base by drying whereby a tacky rubber solvent naphtha may be added slowly to the product is obtained. previously made latex mixture while stirring 4. The method of forming a tacky rubber vigorously. The consistency of the com compound which comprises mixing with a 55 pound may also be varied by a change in the 120 amount of water added. The litharge acts water dispersion of rubber the water soluble as a thickener and also as an accelerator of reaction product of a volatile base and an vulcanization.