GB857514A - Improvements in or relating to the production of emulsion polymers and aqueous mediatherefor - Google Patents

Abstract

An aqueous phase reaction medium for emulsion polymerization consists of a dilute solution of a non-ionic protection colloid, a water-soluble non-ionic emulsifying agent containing a plurality of oxyethylene groups and having a hydrophilic number of 65 to 75, and not more than 1% by weight of the aqueous phase of one or more acetylenic ditertiary alcohols. The preferred acetylenic ditertiary alcohols are symmetrical. Alcohols mentioned are dimethyl hexyne diol and dimethyl octynediol. The preferred protective colloid is polyvinyl alcohol containing at least 95% polyvinyl alcohol which may be supplemented by a smaller amount of another protective colloid such as hydroxyethyl cellulose or gum arabic. Suitable emulsifying agents are polyoxethylated octyl and nonyl phenols and compounds of the general formula (OH) (C2H4O)a (C3H6O)b (C2H4O)cH, wherein a, b and c are such that the molecular weight is 1500-1800, the percentage of oxyethylene groups is 20-50 and the HN value is between 65 and 75. The media may be used for making polymers or co-polymers by dispersing one or more ethylenically unsaturated monomers therein together with a free radical polymerization catalyst (preferably a peroxide) and heating to 140-195 DEG C. Pressure may be employed when gaseous monomers are involved. A blanket of nitrogen is preferably maintained during the reaction. The reaction may be seeded with a small quantity of previously prepared emulsion of polymer of the desired quality and particle size. The particle size of the polymer produced may be controlled by the method of addition of the monomers, and of the catalyst. Detailed procedures are described in the Specification. Examples describe in detail the emulsion polymerization of (1) (2) and (3) vinyl acetate (4) vinyl acetate with a smaller quantity of dibutyl maleate or of various other monomers (5) various terpolymers of vinyl acetate with smaller quantities of other monomers. Many other monomers suitable for polymerization according to the invention, are listed in the Specification. The polymer emulsions produced are useful with or without addition of pigments and plasticizers, as coating compositions, adhesives or for laminating.