Preparation of polyacrylates by emulsion polymerization

摘要

The present invention relates to a process for the preparation of polymers comprising carboxyl groups by emulsion polymerization and the use of the polymers obtainable by this process, for example as thickeners. Moreover, the invention relates to thickener dispersions obtainable by the process and to the use thereof for modifying the rheology of paper coating slips, textile printing pastes, drugs, cosmetic preparations, detergents, cleansing compositions, or foods.

主权项

1. A process for the preparation of polymers, the polymers comprising in a polymerized-in form,
a. M1a+M2a=30 to 70% by weight of an ester of (meth)acrylic acid with a C1-C4-alcohol; b. M1b+M2b=30 to 70% by weight of (meth)acrylic acid; c. M1c+M2c=0.1 to 20% by weight of monomer substituted with at least one C8-C30-radical; and M1d+M2d=0 to 20% by weight of monomers different from a) to c), the process comprising emulsion polymerization with a first polymerization stage followed by a second polymerization stage, wherein the first polymerization stage includes i) providing an initial charge comprising the monomer part amounts M1a, M1b, M1c, and M1d, water, and optionally a surface-active agent, to form a first monomer mixture; ii) heating the first monomer mixture (i) to a temperature in the range of about 30 to 120° C.; and iii) adding a polymerization initiator to form a first reaction mixture, andwherein the second polymerization stage includes
iv) adding the monomer part amounts M2a, M2b, M2c, and M2d to the first reaction mixture (iii) to form a second reaction mixture; and v) after-treatment of the second reaction mixture (iv), wherein
M1b/M1a≧0.4 andM1b/M1a