In an autoclave were placed 1650 ml of water and 9.6 g of itaconic acid. After dissolution a solution of 6 g of sodium hydrogen carbonate in 120 ml of water was added. Subsequently, 98 ml of a 10% aqueous solution of the disodium salt of disulphonated dodecyl diphenyl ether and 49 ml of a 10% aqueous solution of the sodium salt of sulphonated dodecylbenzene were added as emulsifying agents. Then 96 g of n-butyl acrylate, 144 g of vinylidene chloride, 9.8 g of ammonium persulphate, and 4.9 g of potassium metabisulphite were added. The autoclave was sealed and stirring started. Under nitrogen pressure 240 g of vinyl chloride were pressed into the autoclave, which was then heated to 50° C. with stirring. After this temperature had been reached stirring was continued for 15 to 30 min. The temperature of the latex rose to about 65° C. The reaction was continued for about 3 h whereupon the latex was cooled to room temperature. The pH thereof amounted to 2.6 and was adjusted to 6 by means of 100 ml of 1 N aqueous sodium hydroxide. The latex was readily filtrable and contained the copolymer in a concentration of 20%.
