Process for the preparation of polymers having a reduced content of volatile components

The process of the preparation of polymers stabilized with protective colloids in the form of their water-redispersible powders or aqueous dispersions prepared therefrom, said water-redispersible powders and aqueous dispersions prepared therefrom having a reduced content of volatile components, said process comprising:

• a) polymerizing by emulsion or suspension polymerization, one or more primary monomers selected from the group consisting of vinyl esters, (meth)acrylates, vinyl aromatics, olefins, 1,3-dienes and vinyl halides, and optionally, further monomers copolymerizable therewith;
• b) aftertreating the polymer dispersion obtained from said polymerizing by means of postpolymerization, distillation, introduction of steam or inert gas or a combination thereof to obtain a polymer dispersion having a residual content of volatile, nonaqueous components of <2000 ppm:
• c) spray drying the aftertreated polymer dispersion obtained in step b) to obtain a water-redispersible power having a residual content of volatile, nonaqueous components of <400 ppm, the dispersion being adjusted to a solids content of <45% by weight prior to spray drying, and the spray drying carried out with gas at inlet temperature of >120° C., and optionally,
• d) redispersing the resulting powder in water;
• wherein the protective colloids comprise at least one of partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 to 95 mol % and a Höppler viscosity of 1 to 30 mPa·s or partially hydrolyzed, hydrophobically modified polyvinyl alcohols having a degree of hydrolysis of 80 to 94 mol % and a Höppler viscosity of 1 to 30 mPa·s.

A process for the preparation of polymers stabilized with protective colloids in the form of their water-redispersible powders or aqueous dispersions prepared therefrom, said water-redispersible powders and aqueous dispersions prepared therefrom having a reduced content of volatile components, said process comprising;

• a) polymerizing by emulsion or suspension polymerization, one or more primary monomers selected from the group consisting of vinyl esters, (meth)acrylates, vinyl aromatics, olefins, 1,3-dienes and vinyl halides, and optionally, further monomers copolymerizable therewith;
• b) aftertreating the polymer dispersion obtained from said polymerizing by means of postpolymerization, distillation, introduction of steam or inert gas or a combination thereof to obtain a polymer dispersion having a residual content of volatile, nonaqueous components of <2000 ppm;
• c) spray drying the aftertreated polymer dispersion obtained in step b) to obtain a water-redispersible power having a residual content of volatile, nonaqueous components of <400 ppm, the dispersion being adjusted to a solids content of <45% by weight prior to spray drying, and the spray drying carried out with gas at inlet temperature of >120° C., and optionally,
• d) redispersing the resulting powder in water;
• wherein primary monomers or primary monomer mixtures which contain one or more monomers selected from the group consisting of vinyl acetate, vinyl esters of α-branched monocarboxylic acids having 9 to 11 C atoms, vinyl chloride, ethylene, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate and styrene comprise said primary monomers;
• and wherein the protective colloids comprise at least one of partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 to 95 mol % and a Höppler viscosity of 1 to 30 mPa·s or partially hydrolyzed, hydrophobically modified polyvinyl alcohols having a degree of hydrolysis of 80 to 94 mol % and a Höppler viscosity of 1 to 30 mPa·s.