United States Patent Office Patented Dec
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3,483,171 United States Patent Office Patented Dec. 9, 1969 1. 2 Now we have found that copolymers of ethylene and 3,483,171 PROCESS FOR THE PRODUCTION OF COPOLY. at least one vinyl ester, preferably an ester of vinyl alco MERS OF WNYL ESTERS AND ETHYLENE hol and an aliphatic Saturated monocarboxylic acid con Alfred Kiihlkamp, Hofheim, Taunus, and Leonhard taining 1 to 4 carbon atoms, and, if desired, further Reihs, Mainz-Mombach, Germany, assignors to mon.cmers copolymerizable with vinyl esters, can be pre Farbwerke Hoechst Aktiengesellschaft vormals pared with special advantage according to a suspension Meister Lucius & Bruning, Frankfurt am Main, polymerization process under the action of a free radical Germany, a corporation of Germany polymelization catalyst by placing the aqueous phase, No Drawing. Filed July 15, 1965, Ser. No. 472,338 which contains at least one known suspension stabilizer Claims priority, application Germany, July 18, 1964, in the dissolved state, in the polymerization vessel, intro F 43,493 O ducing ethylene under a pressure of up to 300 atmospheres Int. C. CO8f 15/40, 15/16 gage, preferably under a pressure within the range of 10 U.S. C. 260-80.6 8 Claims to 100 atmospheres gage, and maintaining the respective ethylene pressure at temperatures within the range of from ABSTRACT OF THE DISCLOSURE 40 to 120° C., preferably within the range of from 60 A process for producing copolymers of ethylene, vinyl to 85 C., and metering in the vinyl ester or the vinyl esters and, if desired, up to 50% by weight of the vinyl esters containing the catalyst in the dissolved state, if de ester of unsaturated comonomers that are copolymerizable sired, together with the other monomers copolymerizable with the vinyl esters. Polymerization is effected in aqueous with vinyl esters, during the reaction in a continuous man suspension with a free radical catalyst using an ethylene 20 ner, for example in the course of 2 to 10 hours, prefer pressure up to 300 atmospheres. The process is charac ably in the course of 3 to 6 hours, in an appropriate man terized by the fact that the vinyl ester with the catalyst ner, for example by means of an apertured nozzle. dissolved therein is fed incrementally to the reaction mix When working according to the process of the present ture to produce copolymers having a relatively higher invention there are obtained, under the same ethylene ethylene content. In accordance with a particularly ad preSSures, suspension copolymers whose ethylene content vantageous modification, the vinyl ester solution of cata is higher than the ethylene content of the suspension co lyst is sprayed into the vapor phase above the liquid re polymers prepared by the process described in U.S. Patent action mixture. The products may be used as primers 2,485,796 according to which the total amount of the vinyl for lacquers, adhesives for bonding sheets and interlayers ester is placed in the polymerization vessel. of safety glass, thermoplasts and vibration-damping ma 30 According to a particularly advantageous modification terials. of the process of the present invention the vinyl ester is -lates comm metered in by means of an atomizer nozzle disposed above the liquid level since by this method the vinyl ester is at The present invention relates to a process for the pro Once charged with ethylene to the maximum extent. duction of copolymers of vinyl esters and ethylene. The table hereunder shows the ethylene content of the It is known that copolymers of vinyl acetate and ethyl copolymers in dependence on the ethylene pressure ap ene can be prepared in bulk, in solution, in emulsion and plied and the method of metering in the ethylene. in suspension. The present invention is directed to a process for the Percent of Percent of 40 ethylene ethylene production of copolymer suspensions of vinyl esters and content content ethylene which enables large portions of ethylene to be (introduction (introduction by means of by means of incorporated into the copolymer even at relatively low an apertured an atomizer ethylene pressures. nozzle) nozzle) In U.S. Patent 2,485,796 there is described a process Ethylene pressure (atmospheresgage): for the production of granular copolymers of vinyl ace 10---------------------------------- 3.8/2.9 4.5/4.8 7.5/6.5 8.0/7.9 tate and ethylene in which all reacants are placed in the 8.2/10.0 9.9/11.2 reaction vessel. When using the process of U.S. Patent 16.2/16.8 20.3/21.5 2,485,796 in tests for the production of copolymer sus 29.6/30. 1 38.9/40.5 pensions from vinyl acetate and ethylene under different 49.4/50.7 57.8/58, 3 ethylene pressures, the following copolymers were ob 50 The process according to the invention is, moreover, tained with an ethylene content as shown in the table characterized by the fact that suspension copolymers are hereunder. obtained thereby which, besides having high K values Ethylene pressure Ethylene content (determined according to Fikentscher), practically have (atmospheres gage): (percent) no content of residual monomer. 10 -------------------------------- 1.0/1.2 When Working according to the new method, suspen 15 -------------------------------- 4.1/4.7 sion stabilizers known per se are used, for example poly 20 -------------------------------- 5.5/6.1 vinyl alcohols, water-soluble salts of copolymers of un 50 -------------------------------- 12.2/11.0 Saturated mono- or dicarboxylic acids, such as the am 150 ------------------------------- 24, 1/24.5 60 monium salt or the alkali metal salts of copolymers of 300 ------------------------------- 37.0/37.2 styrene and maleic anhydride, for example of a copoly mer of the aforementioned monomers having a monomer It is also described in U.S. Patent 2,485,796 that the ratio of 1:1, furthermore water-soluble cellulose deriva copolymers produced have a substantial residual monomer tives. content of vinyl acetate which has to be removed by Exemplary of the free radical polymerization catalysts distillation. 65 that may be used in the process of the invention are 3,483,171 3 4 organic per-compounds soluble in vinyl esters, for ex EXAMPLE 5 ample diacyl peroxides such as dibenzoyl peroxide, di lauroyl peroxide, above all azo compounds, for example This example was carried out under the same condi azobisisobutyronitrile. tions as those described in Example 1 except that the As monomers which are copolymerizable with vinyl ethylene pressure was adjusted at 150 atmospheres gage. esters and which may also be used in the process of the 5 The copolymer had an ethylene content of 38.9% and invention, there may be mentioned, for example, acrylic a K value of 93.9. acid and methacrylic acid or esters of the aforementioned EXAMPLE 6 acids and aliphatic saturated monohydric alcohols con This example was carried out under the same condi taining 1 to 8 carbon atoms, furthermore semi-esters or tions as those described in Example 1 except that the di-esters of a,6-unsaturated dicarboxylic acids, for ex 10 ethylene pressure was adjusted at 300 atmospheres gage. ample semi-esters of maleic acid or fumaric acid and The copolymer had an ethylene content of 49.4% and aliphatic Saturated monohydric alcohols containing 1 to 8 a K value of 83.1. carbon atoms, furthermore vinyl sulfonic acid or the EXAMPLE 7 alkali metal salts thereof. The aforementioned monomers 5 This example was carried out under the same condi which are copolymerizable with vinyl esters may be used tions as those described in Example 3 except that n-vinyl in amounts up to 50%, calculated on the weight of the butyrate was used instead of vinyl acetate at a pressure vinyl ester or vinyl esters. of 20 atmospheres gage. The copolymer had an ethylene The colorless copolymers may be used in the lacquer content of 9.3% and a K value of 72.7. industry as primers and adhesives in a variety of fields, 20 for example for the bonding of sheets and interlayers of EXAMPLE 8 safety glass, as thermoplasts, as vibration-damping mate This example was carried out under the same condi rial, and the like. The copolymers may be hydrolized to tions as those described in Example 3 except that there yield modified polyvinyl alcohols which, depending on the was present an additional amount of 50 grams acrylic ethylene content, are soluble or swellable in few solvents 25 acid. The copolymer had an ethylene content of 8.6% only and may be shaped in the thermoplastic state into a and a K value of 68.9. variety of products. The following examples serve to illustrate the inven EXAMPLE 9 tion, but they are not intended to limit it thereto: This example was carried out under the same condi 30 tions as those described in Example 3 except that there EXAMPLE 1. was present an additional amount of 50 grams 2-ethyl hexylacrylate. The copolymer had an ethylene content Recipe of 8.9% and a K value of 79.2. 2700.0 grams of water 2.0 grams of a suspension stabilizer such as, for ex EXAMPLE 10 ample, polyvinyl alcohol, ammonium salt of maleic This example was carried out under the same condi anhydride/styrene (molar ratio 1:1)-copolymer tions as those described in Example 3 except that there 1000.0 grams of vinyl acetate was present an additional amount of 10 grams vinyl 1.0 gram of azobisisobutyronitrile. sulfonic acid. The copolymer had an ethylene content of The amount of water and the suspension stabilizer 40 9.8% and a K value of 76.5. were placed in an autoclave made of stainless steel EXAMPLE 11 (capacity: 5 l.) fitted with stirring means, thermometer This example was carried out under the same condi and dosing openings.