GB1332469A - Polymer and process - Google Patents

Abstract

1332469 Porous polyester granules BALM PAINTS Ltd 15 Dec 1970 [22 Dec 1969] 59518/70 Headings C3C and C3P Porous cross-linked polyester granules are made by forming a solution of an unsaturated xylene soluble polyester resin containing free carboxyl groups in an essentially water insoluble polymerizable unsaturated monomer and suspending this solution as discrete globules in an aqueous continuous phase in the presence of from 0À3 to 10À0 equivalents per free carboxy group of a base having a dissociation exponent i.e. -log 10 K b where K b is the dissociation constant of the base in water at 25‹ C., less than 8, initiating polymerization to cross-link the polyester resin, recovering the granules and allowing them to dry in air until the liquid has diffused out of them. If desired droplets of an aqueous liquid may be pre-dispersed within the polyester solution before dispersion of this solution in the continuous phase. The polyester resin is selected by the following test, to a xylene solution of the resin is added with mild agitation 5% by weight of an aqueous solution of ammonia and the mixture examined under an electron microscope to determine if a stable dispersion of droplets has formed and provided the mixture is essentially free of disperse particles greater than 5 microns and remains so for up to 30 minutes the resin is regarded as satisfactory. The unsaturated polyester resin contains an alpha, beta, ethylenically unsaturated acid such as maleic, fumaric, itaconic, citraconic or mesaconic acid. The preferred monomers are styrene, alpha-methyl styrene, divinyl benzene and nucular-substituted vinyl toluene. In addition minor amounts of other polymerizable monomers may be present such as acrylic and methacrylic acid esters, acrylonitrile, vinyl acetate, tetra-allyl ethoxyethane, ethylene glycol dimethacrylate, or triallyl cyanurate. The base may be an inorganic base of which ammonium hydroxide is preferred, or an aliphatic amine of which a long list is given. The polymerization within the globules is initiated by free radical compounds such as an organic peroxide or azo-compound or by exposure to a radiation source such as radioactive cobalt of ultra-violet light. The polyester resin may contain pigments e.g. TiO 2 . The aqueous phase may contain surface active agents, and thickeners such as hydroxyethylcellulose or polyvinyl alcohol. Exemplified polyesters are made from fumaric acid, phthalic anhydride and propylene glycol and maleic anhydride, phthalic anhydride and propylene glycol. The granules are used as matt texturing, flatting and opacifying agents in paint compositions. The granules may also contain pigment particles e.g. TiO 2 , by forming the granules in the presence of the pigment. Examples 7, 8, 10 and 11 relate to paint compositions and example 9 to the preparation of an opaque sheet.