METHOD FOR PREPARING AQUEOUS VINYL POLYMER DISPERSIONS Russian patent published in 2017 - IPC C08F265/06 C08F2/26 C08F2/44 C09D5/02 C09D151/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for preparing aqueous dispersions of vinyl polymers. Method of producing aqueous dispersion of multiphase particles of hydroplasticisable vinyl polymer involves: (1) first polymerisation step, including: (1a) preparing emulsion (1A) in water of a first mixture of monomers (1a1), surfactant (1a2) and a water-soluble inorganic salt (1a3), wherein first mixture of monomers (1a1) comprises: 1) monomers with carboxylic acid functional group, 2) optionally cross-linking monomers different from 1, 3) vinyl monomers, different from 1) and 2), and 4) optionally, chain-transfer agents, wherein surfactant (1a2) is an anionic surfactant based on sulphur, containing less than 50 wt% ethylene oxide, and wherein content of water-soluble inorganic salt (1a3) at moment of beginning polymerisation (1b) ranges from 0.01 to 3 g/kg of water, (1b) emulsion polymerisation of produced emulsion 1A to obtain dispersion particles of hydroplasticisable polymer of first step (1B), wherein said polymer of first step stage has T_c, calculated from Fox equation, from 10 to 125 °C, wherein said first dispersion of particles (1B) has particle size less than 50 nm (Z-average measured by dynamic light scattering); (2) second polymerisation step, including: (2a) adding to dispersion 1B a second mixture of monomers (2a1), containing: 1) monomers selected from same group as first mixture of monomers (1a1), 2) optionally monomers (2a2), containing 2 or more ethylenically unsaturated groups for preliminary cross-linking, preferably less than 2 wt%, wherein monomers with carboxylic acid functional group in second mixture of monomers are present in such quantity, that acid number of obtained second polymer is less than 23 mg KOH/g, and wherein amount of mixture of monomers (2a1) ranges from 10 to 90 wt% of total weight of mixture of monomers (1a1) plus (2a1), (2b) polymerisation of second mixture of monomers (2a1) to produce second step polymer in first dispersion of particles (1B) to obtain dispersion of multiphase particles (2B), (3) optionally hydroplasticising dispersion of multiphase particles (2B) by adding a base, preferably a volatile base to pH from 6.5 to 10, preferably 9, (4) optionally adding separate cross-linking agent for reaction with cross-linking monomers in mixtures of monomers (1a1) or (2a1) or with unsaturated groups (2a2). Disclosed is a dispersion of multiphase particles of vinyl polymer, coating composition, method of producing coating composition and use of multiphase dispersion of particles of vinyl polymer.

EFFECT: technical result is coating compositions based on dispersion have excellent stability of viscosity, coatings are chemically resistant to various media, have sufficient hardness and are transparent.

23 cl, 6 tbl, 10 ex