| 摘要 |
Alkali-soluble resins having an acid number of 140-300 and a number average molecular weight of 700-5000 comprise units of at least one monomer of the formula Ar-CH=CH2 where Ar is an aryl or alkaryl group, and units of acrylic and/or methacrylic acid, the mole ratio of the former units to the latter being from 3:1 to 1:1, the resin being substantially free from any solvent used in its preparation. The aromatic monomer is preferably styrene and/or vinyl toluene. The resin may also contain units of other monomers, e.g. N-vinyl pyrrolidone, 2 - methyl - 5 - vinyl pyridine, acrylonitrile, diethyl aminoethyl methacrylate, alkyl acrylates and methacrylates, and dimethyl or diethyl esters of fumaric or itaconic acid. The resins are obtained by solution polymerization of the corresponding monomers in a solvent having chain-transfer properties, preferably with controlled incremental addition of the various components. Suitable solvents include methyl isobutyl ketone, toluene, ethylbenzene, xylene/p - cymene mixtures, 3 - heptanone, isoamyl acetate, methyl isobutyl carbinol, ethylene glycol monobutyl ether, cyclohexanone, carbon tetrachloride and mixtures thereof. An additional chain transfer agent, e.g. lauryl mercaptan, may also be included in the polymerization. Catalysts such as benzoyl peroxide and azobisisobutyronitrile can be used to initiate the reaction. Alkaline aqueous solutions (resin cuts) are formed by treating the solvent-free resin products with aqueous bases, e.g. ammonium hydroxide, sodium or potassium hydroxide, borax and amines. Examples 22 and 23 illustrate the use of such ammoniacal styreneacrylic acid resin cuts as emulsifying agent in the emulsion polymerization of methyl methacrylate or styrene using ammonium persulphate as initiator. Example 21 illustrates the use of an ammoniacal styrene-acrylic acid resin cut as a levelling agent in a floor-coating composition comprising a polystyrene emulsion, a polyethlene wax emulsion, tributoxyethyl phosphate and polyethylene glycol dibenzoate. |
