Patent GB-1003318-A (GB)
Title: Improvements in the manufacture of copolymers
Inventor: SMITH JOHN LIBERTY
IPC: C09D151/00
Filed: 1961-08-23
Abstract: Alkali-soluble copolymers are made by copolymerizing an acrylic or methacrylic ester with an unsaturated carboxylic acid to form an alkali-soluble copolymer in the presence of an aqueous solution or dispersion of a preformed alkali-soluble copolymer of an acrylic or methacrylic ester.  The preformed copolymer has a composition which may or may not be the same as that of the copolymer subsequently formed. The copolymers are derived from esters such as methyl, ethyl, butyl and 2-ethylhexyl acrylates, or methyl and ethyl methacrylates, acids such as acrylic, methacrylic and itaconic acids, and, optionally, other monomers such as styrene, vinyl acetate, butadiene, isoprene, methyl iso propenyl ketone, allyl alcohol, hydroxyethyl acrylate, ethoxyethyl methacrylate, acrylamide, methacrylamide, methylol acrylamide and acrylonitrile.  In the preparation of the preformed copolymer dispersing agents, e.g. sodium dodecyl benzene sulphonate, sodium naphthalene sulphonate/ formaldehyde condensate and sodium lauryl sulphate, are used, but in the second stage of polymerization no additional dispersing agent is used.  Both stages of polymerization may be carried out with gradual addition of monomers and catalyst, e.g. potassium persulphate, to the reaction medium.  The preformed copolymer may be used either in the free-acid or salt form. The examples describe the preparation of the following first stage copolymers (a), and second stage copolymers (G): (1) (a) and (b) ethyl acrylate / methyl methacrylate / methacrylic acid, (2) (a) and (b) ethyl acrylate/vinyl acetate/ methacrylic acid, (3) (a) and (b) ethyl acrylate/ styrene/methacrylic acid, and (4) (a) ethyl acrylate/styrene/methacrylic acid and (b) ethyl acrylate / styrene / 2 - ethylhexyl acrylate/ methacrylic acid.  The polymer emulsion of (4) is formed into a coating composition by neutralization with dimethylaminoethanol, followed by the addition to the resulting polymer solution of titanium dioxide and a water-soluble melamine-formaldehyde resin.ALSO:Surfaces of wood and steel are coated by applying thereto an emulsion or solution of an alkali-soluble copolymer made by copolymerizing an acrylic or methacrylic ester with an unsaturated acid in the presence of an aqueous solution or dispersion of a preformed alkali-soluble copolymer of an acrylic or methacrylic ester, which preformed polymer may have the same composition as the copolymer subsequently formed (see Division C3).  In Examples (1-3), wood boards primed with matt black paint are coated by brushing with emulsions containing titanium dioxide and first- and second-stage copolymers which are of identical composition and which are: (i) ethyl acrylate/methyl methacrylate/methacrylic acid, (ii) ethyl acrylate/vinyl acetate/methacrylic acid, and (iii) ethyl acrylate/ styrene/methacrylic acid.  In Example (4) mild steel panels are coated with a composition comprising titanium dioxide, a water-soluble melamine-formaldehyde resin and a copolymer solution obtained by adding diethylaminoethanol to a copolymer emulsion containing an ethyl acrylate/styrene/methacrylic acid first-stage copolymer and an ethyl acrylate/styrene/2-ethylhexyl acrylate/methacrylic acid copolymer, and finally baked.