GB1461840A - Preparation of polymers - Google Patents

Abstract

1461840 Polymerization in tetrahydronaphthalenes as solvent HOECHST AG 10 May 1974 [26 May 1973] 20858/74 Heading C3P In the polymerization of (1) a mono- and/or di-olefinically unsaturated monomer containing no free carboxyl or anhydride groups with (2) a mono- or di-carboxylic olefinically unsaturated monomer or derivative thereof, the polymerization is carried out at elevated temperature in the presence of a catalyst and tetrahydronaphthalene (or derivative thereof) as solvent with concomitant removal of any water present. The tetrahydronaphthalene derivative may be mono-substituted by C 1-4 alkyl, preferably methyl or ethyl. A constant reaction temperature in the range 150-205‹ C. is achieved by the formation of a binary or tertiary azeotropic mixture comprising water, organic solvent and/ or monomers. Solvent and unreacted monomers removed with the water through volatilization are recovered and recycled to the reaction mixture without purification. In batch operation 20-70% of the total amount of solvent used is heated to the desired polymerization temperature and then a solution, in the residual solvent, of the starting monomer mixture is gradually added to the heated solvent. The residual solvent may include solvent additional to the tetrahydronaphthalene. Monomer (1): styrene, α-methyl styrene, vinyl toluene, C 1-6 esters and hydroxyesters, amides and nitriles of acrylic and/or methacrylic acid, and diallyl phthalate. Monomer (2): maleic, acrylic, methacrylic, citraconic, itaconic and #-1,2- or # - 4,5 - tetrahydrophthalic acids, or an anhydride of any of these acids, if such exists. The additional solvent may be a diol having 2 to 4 carbon atoms or an ether thereof, methyl ethyl ketone, diacetalcohol, aceto-acetate and ethyl or butyl acetate. The reaction mixture, which is quenched to a temperature below 100‹ C. after the desired polymerization has been achieved, also includes peroxide catalysts (specified) and a chain regulator, e.g. dodecyl mercaptan. According to Example 1 the reaction mixture consisted of styrene, maleic anhydride, tetrahydronaphthalene, ethylene glycol monoethylether and monobutyl ether, di-t-butyl peroxide and dodecyl mercaptan. In further Examples the catalyst was 2,5-dimethyl hexane-2,5-di-tbutylperoxide or dicumyl peroxide, and the additional solvent diacetone alcohol or isobutanol. Examples 9 and 10 relate to copolymers obtained by polymerizing styrene, vinyl toluenes, methyl methacrylate (or acrylonitrile), butyl acrylate and acrylic acid.