Patented Aug. 5, 1947 ' 2,425,191

UNITED‘ STATES PATENT OFFICE 2,425,191 POLYMERIZATION OF ACRYLATES, METH ACRYLATES ALONE OR IN MIXTURES, AND PRODUCTS THEREOF Edward L. Kropa, Fairfield, Conn., ass-7gnor to American Cyanamid Company, New York, N. Y., a corporation of Maine ' No Drawing. Application July 13, 1944, Serial No. 544,826 7 Claims. (01. 260-84) 1 2 This invention relates to the production of Example 1 thermoplastic polymeric materials. Parts The use of polymers of various unsaturated Zinc chloride 72 substances has previously been somewhat limited Water 18 because suitable solvents for many such sub Acrylonitrile ______10 stances and the polymers thereof have not been Benzoyl peroxide ______0.002 known. One of these, polyacrylonltrile, is in soluble in most of the known solvents. Accord To a solution of the zinc chloride in the water, ingly, this material, as Well as many of the other the acrylonitrile with the benzoyl peroxide dis polymeric materials producedirom unsaturated 10 solved therein is added. This composition is compounds, has not attained any substantial com heated at about 90° C. for 4-5 hours during which mercial utilization in the production of arti?cial ' time the solution changes to a thick viscous mass. This viscous mass is poured into a relatively large ?bers, ?lms, etc. Previously polymerization of unsaturated com volume of water, thereby precipitating a poly pounds has been carried out in a variety of 15 meric powder. This powder may be separated by organic solvents. In certain instances aqueous ?ltration, washed with water and dried. This emulsions have been employed. In both in dried material may be subjected to heat and pres stances, solutions or suspensions have been sure to produce molded articles having excellent chemical resistance and also being very resistant formed. ' An object of this invention is to provide a sol 20 to heat.‘ The dried powder may also be sheeted vent‘ material and to so polymerize various un on hot mill rolls (e. g., 150° C.) to yield tough saturated materials such as acrylonitrile, that clear ?lms. ~ concentrated solutions of the polymeric material The ?ltrate which contains the zinc chloride thus produced may be obtained. may be concentrated in any suitable apparatus by heating at about 100° C. for sufficient time to Another object of this invention is to produce 25 solutions of polymeric materials suitable for the volatilize enough water so that the concentrate production of arti?cial ?bers, ?lms, etc. is again suitable for re-use in polymerizing/an Still another object of this invention is to poly other batch of acrylonitrile or other polymeriz merize unsaturated materials in salt solutions able material. from which the polymer may be precipitated. 30 Example 2 These and other object are attained by poly ' ' Parts merizing in an aqueous solution of a zinc salt Acrylonitrile 8 which is extremely water-soluble, a substance of the following general formula: Zinc chloride '74 Water ____ 18 i‘ The acrylonitrile is mixed with a solution of the crn-w-m zinc chloride in the water. This solution becomes and isomers thereof, where R is hydrogen or slightly warm during mixing. It is heated for methyl, where R1 may be —CN or about 5 hours at 90° C. and then aged for about -—C R: 40 2 weeks at room temperature to increase the vis» H cosity thereof. o The solution may be extruded through a nozzle where R2 is hydrogen, alkyl, alkaryl, cycloalkyl, or or spinneret whose internal diameter is approxi mately 0.1 millimeter. The material is ‘preferably / extruded into warm Water ('70-80° C.) under a ——N \ pressure of about 35-40 pounds per square inch. R4 Under these conditions a ?ber is formed and co and where Re and R4 are hydrogen or organic agulated which may be drawn at approximately radicals. Zinc salts suitable for the purposes of 40 feet per minute. Utilizing somewhat lower this invention are those, a unit weight of which 50 temperatures, i. e., 67° C. and a pressure of about will dissolve in less than 0.3 of a unit weight of 1'70 pounds per square inch a ?ber is formed cold water. which may be drawn at about 30 feet per minute. The following examples in which the propor In order to increase the strength of the ?bers tions are in parts by weight are given by way of produced it is desirable that they be drawn in illustration and not in limitation. 65 such. a manner that they will be stretched to a 2,425,191 3 4 substantial extent. This may be. conveniently merizes during this time and the product may be done in the coagulating bath. The stretching utilized in the same general manner as described tends to increase the strength of the ?bers as in Examples 1 and 2. compared to those which are merely extruded. Somewhat better results are obtained by allow Example 8 ing the ?ber to contract and then subjecting it Parts to another stretching operation. ' Vinyl acetate ______25 An 80% solution of zinc chloride in water--- 100 Example 3 The vinyl acetate is dissolved in the zinc chloride Parts 10 A 75% solution of zinc'chloride in water____.. 54 solution and a few milligrams of benzoyl peroxide Acrylonitrile ______25 are added thereto. The mixture is then exposed Benzoyl peroxide ______0.1 to a source of ultra-violet light such as a mercury arc for about 2-3 hours. The vinyl acetate poly The acrylonitrile is dissolved in the zinc chloride merizes during this time and the product may be solution and the mixture becomes very warm, 15 utilized in the same general manner as described thereby indicating the possibility of a chemical in Examples 1 and 2. reaction between the monomeric acrylonitrile and the zinc chloride. The benzoyl peroxide is added Example 9 and the mixture is heated for about 1/2 hour at ‘ Parts 90-95“ C. A rubbery gel is obtained. This gel 20 Methyl methacrylate ______5 may be washed with hot water until substantially An 80% solution of zinc chloride in water_-__ 10 free of zinc chloride solution. The resulting com position, which resembles crepe rubber when hot, The methyl methacrylate is dissolved in the zinc chloride solution and a few milligrams of benzoyl may be milled on hot rolls at about 150-160" C. to produce extremely tough transparent ?lms. peroxide are addedlthereto, thereby forming a 25 Slightly pink solution. The mixture is then ex Example 4 posed to a source of ultra-violet light such as a Parts mercury are for about 2-3 hours. The methyl Methacrolein ______25 _methacrylate polymerizes during this time and A 75% solution of zinc chloride in water____ 25 the product may be utilized in the same general 80 manner as described in Examples 1 and 2. The methacrolein is dissolved in the zinc chloride solution and a few drops of t-butyl peroxide are Example 10 added. A solid somewhat opaque gel is obtained Parts after about 12 hours at room temperature. This Methyl itaconate ______5 may be oxidized to produce a water-soluble poly An 80% solution of zinc chloride in water--- 10 mer. Example 5 The methyl itaconate is dissolved in the zinc

» ‘ Parts chloride solution and a few milligrams of benzoyl Methacrolein ______.. 7 peroxide are added thereto. The mixture is then Acrylonitrile ______7 (0 exposed to a source of ultra-violet light such as v A 75%‘ solution of zinc chloride in water____ 12 a mercury are for about 5-8 hours. The methyl itaconate polymerizes during this time and the The methacrolein and acrylonitrile are dissolved product may be utilized in the same general man in the zinc chloride solution and a few drops of ner as described in Examples 1 and 2. t-butyl peroxide are added. Upon standing at room temperature for about 12 hours, a clear Example 11 yellow viscous material is obtained which may be Parts molded or extruded in the same general manner Acrylonitrile ______- 10 as described in Examples 1 and 2, respectively. An 80% solution of zinc chloride in water"- 90 Example 6 50 The acrylonitrile is dissolved in the zinc chloride Parts solution and is polymerized by heating in the Methyl acrylate ______5 presence of a small proportion of benzoyl per An 80% solution of zinc chloride in water___ 10 oxide at about 90° C. for about an hour. A small proportion of a water-dispersible dye, e. g., Calco The methyl acrylate is dissolved in the zinc chlo 55 Brillian Pigment Blue BN, is dispersed in the ride solution and a few milligrams of benzoyl solution containing the polymerized acrylonitrile. peroxide are added thereto. The mixture is then The resulting composition is applied to cloth in exposed to a source of ultra-violet light such as the same general manner as in textile printing. a mercury arc for about 2-3 vhours. Optionally The cloth is then immersed in water, thereby heat may be applied in the same general manner 60 precipitating the resin and the color material. as described in the preceding examples in addi The treated cloth shows no leaching of the color tion to, or instead of, ultra-violet radiation. The material upon washing with soap and hot water. methyl acrylate polymerizes during this time and the product may be utilized in the same general Example 12 manner as described in Examples 1 and 2. Parts 65 25% ethyl acrylate-75% acrylonitrile mix Example 7 ture ______14 Parts A 75% solution of zinc chloride in water___.. 86 Vinyl acetate ______5 Benzoyl peroxide ______0.1 An 80% solution of zinc chloride in water... 10 70 The mixture of ethyl acrylate and acrylonitrile is The vinyl acetate is dissolved in the zinc chloride dissolved in the solution of zinc chloride and the solution and a few milligrams of benzoyl peroxide benzoyl peroxide is added. The resulting solution are added thereto. The mixture is then exposed is heated at about 90-100° C. for ‘/z—2 hours there to a source of ultra-violet light such as a mercury by causing the ethyl acrylate and acrylonitrile to arc for about 2-3 hours. The vinyl acetate poly 75 polymerize. The resulting polymer may be recov 2,425,191 ' a . ered and employed in molding as in Example 1 solutions of many substances which will dissolve or the solution may be extruded as in Example 2.". the polymerizable materials inhibit polymeriza Methyl acrylate. propyl acrylate. n-butyl ac tion and therefore are not suitable for use accord rylate, etc., may be substituted for part or all ing to this invention. Examples of such sub of the ethyl acrylate employed in Example 12 in stances are' sodium thiocyanate, potassium thio order to obtain products having different physi cyanate, zinc thiocyanate, etc. These substances cal properties. In some cases it may be desir are such active polymerization inhibitors that in able to employ a mixture of several acrylates with some instances they are especially useful in sta acrylonitrile such as a mixture containing 5% bllizing substances such as acrylonitrile against each of methyl, ethyl, n-propyl and n-butyl ac 10 polymerization. Small amounts of some of these rylates and 80% of acrylonitrile. The total pro materials, e. g., sodium thiocyanate and potas portion of the esters of acrylic acid should be at sium thiocyanate. may be incorporated into po least 5% based upon the total weight of the tentially polymerizable materials in order to sta polymerizable substances employed. bilize them over relatively long periods or time. Methyl methacrylate may be substituted in 15 These substances are particularly suitable since whole or in part for the ethyl acrylate employed they may be easily separated from the polymer in Example 12 and the former may be replaced izable material merely by distillation leaving the in part with othermgethacrylates such as ethyl salt used as a residue. methacrylate. n-propyl methacrylate, n-butyl Fillers‘and/or pigments may be mixed with methacrylate. Furthermore, the methacrylates 20 the polymeric products to produce molding com .may be employed along with methyl, n-propyl positions. Examples of these are: wood ?our, ~ and n-butyl acrylates, as well as other such com wood ?ber, paper dust, clay, zein, glass wool, foli pounds. Such compositions may contain, for ex— ated glass, mica, granite dust. silk ?ock, cotton ample, about 75% acrylonitrile, 5% methyl meth ?ock, steel wool, silicon carbide, paper, cloth, acrylate, 5% ethyl methacrylate, 5% n-propyl 25 sand, titanium oxide, lithopone, lead. oxide, methacrylate,2%.-.hutylmethacrylate and 5% of chrome yellow, lead cyanamide, zinc cyanamide, any one of the esters of acrylic acid mentioned in etc. the preceding paragraph. Polymeric materials made according to my in- . Among the substances which may be polymer- ' vention have a wide variety of applications. The ized in the same general manner as described 30 solutions produced according to the above de herein are: methacrylonitrile, ethyl acrylate, n scription may be extruded to form ?laments, propyl acrylate. isopropyl acrylate, butyl acrylate. ?lms, ribbons, or tubes. They may be used in the isobutyl acrylate, ethyl methacrylate, propyl manufacture of woven fabrics, gaskets, electrical methacrylate, butyl methacrylate, cyclohexyl insulation, heat insulation, etc. The polymeric methacrylate, allyl acetate, methallyl acetate, 35 materials may be molded to form gaskets, pack methacrylamide, methyl vinyl ketone, etc. Ob ing glands, electrical insulators, novelties, etc. viously various mixtures of these substances'or The polyacrylonitrile materials are particularly mixtures of these substances with any of those suitable for such purposes wherein it is desirable described in the above examples may be used "in -. to have materials which are resistant to grease, the same general manner as the individual sub 40 organic solvents, water, heat, etc. stances. This applic‘atio'n'is a continuation-in-part of In some instances it may be desirable to co my copending application, Serial No. 331,756, ?led polymerize'two‘ or more unsaturated materials of April 26, 1940, now Patent No. 2,356,767, issued the type described above or one 01' the type de August 29, 1944. scribed above with some other reactive polymer 45 Obviously many modi?cations and variations izable material. For certain purposes it may be may be made in the processes and compositions advantageous to use a substance containing an described above without departing from the spirit amide group, e. g., acrylamide, in order to incor and scope of the invention as de?ned in the ap porate in the polymer groups having an affinity pended claims. ' for acidic dyes. Similarly. acrylic acid might be 60 I claim: used in the co-polymer thereby giving it an a?in 1. A process which comprises polymerizing an ity for basic dyes. ' alkyl ester of acrylic acid in which the alkyl Among the zinc salts which are suitable for group contains from 1 to 4 carbon atoms in an the solvent medium the following are preferred: at least 65% solution of zinc chloride in water. zinc chloride, zinc bromide and zinc iodide. Mix 55 2. A process which comprises polymerizing eth tures of these are also useful. It is necessary yl acrylate in an at least 65% solution of zinc that the solution of the zinc salts be highly con chloride in water. centrated for the purposes of this invention. Ac 3. A process which comprises polymerizing an cordingly, the solutions should contain at least alkyl ester of methacrylic acid in which the alkyl 65% of the zinc salt. 60 group contains from 1 to 4 carbon atoms in an at Other salts may be added after polymerization, least 65% solution of zinc chloride in water. e. g., sodium chloride, aluminum chloride, mag 4. A process which comprises polymerizing a nesium chloride, etc., in order to aid thecoagula~ mixture including acrylonitrile and at least 5% tion. Various polymerizing catalysts may be sub 65 based on the total weight of polymerizable sub stituted for all or part of the benzoyl peroxide stances of an alkyl ester of acrylic acid in which or t-butyl peroxide, e. g., lauroyl peroxide or co the alkyl group contains from Ito 4 carbon atoms coanut oil peroxide, stearyl peroxide, aluminum in an at least 65% solution of zinc chloride in chloride, etc. A polymerization catalyst’is not water. necessary since the zinc salt acts as a catalyst 70 5. A process as in claim 4 wherein the alkyl itself although the reaction goes much more slow ester of acrylic acid is ethyl acrylate. ly and therefore it is generally desirable to use 6. A process which comprises polymerizing an polymerization catalysts as indicated in the above ‘ examples. alkyl ester of acrylic acid in which the alkyl group contains from 1 to 4 carbon atoms in an at least It is to be noted that concentrated aqueous 75 65% solution in water of a substance selected 2,425,191 from the group consisting of zinc chloride, zinc " bromide and zinc iodide. REFERENCES CITED 7. A process which comprises polymerizing an The following references are of record in the alkyl ester of methacrylic. acid in which the alkyl ?le or this patent: group contains from 1 to 4 carbon atoms in an at least 65% solution of a, substance selected 5 UNITED STATES PATENTS from the group consisting of zinc chloride, zinc Number Name Date bromide and zinc iodide in water. ‘ 2,140,921 Rein ______.. Dec, 20, 1938 EDWARD L. KROPA. 2,356,767 Kropa. ______.._ Aug. 29, 1944