GB871218A - Esters of perfluorochloro aliphatic carboxylic acids - Google Patents

Abstract

Fluorine-containing polymers are prepared by polymerizing an ethylenically unsaturated ester of a perfluorochloroaliphatic carboxylic acid in which the ester group is derived from an ethylenically unsaturated alcohol containing from 1 to 20 carbon atoms. The esters may be homopolymerized e.g. by heating in the presence of benzoyl peroxide or copolymerized with other ethylenic monomers. Comonomers specified are chlorotrifluoroethylene, 1, 1-dichlorodifluoroethylene, bromotrifluoroethylene, chloropentafluoropropene, tetrafluoroethylene, hexafluorobutadiene, hexafluoropropene, fluoroprene, chloroprene, chlorofluoroethylene, vinylidene fluoride or chloride, trifluorobutadienes, trifluoromethyl butadienes, trifluoromethyl styrenes, ethylene, propene, butadiene, styrene, vinyl isobutyl ether, methyl methacrylate, butyl acrylate, vinyl butyrate, vinyl acetate, acrylonitrile, acrylamide, fluoroacrylonitrile and trifluoromethyl acrylonitrile. The copolymerization may be carried out in a water suspension using a redox catalyst comprising an inorganic persulphate and an inorganic bisulphite. Buffers, e.g. sodium tetraborate and activators such as ferrous sulphate or nitrate may also be included. A dispersing or emulsifying agent may be used which is a salt, e.g. potassium or ammonium of a perfluorocarboxylic acid or a perfluorochloroaliphatic carboxylic acid, e.g. the acid from which the ester to be polymerized is derived. The copolymerization may also be carried out in the presence of peroxide catalysts. Examples describe the homopolymerization of allyl trichloro-octafluoro-hexanoate, allyl tetrachloroundecafluoro-octanoate and di-allyl trichlorononafluoro suberate and the copolymerization of these three esters with various halogenated ethylenes and butadienes. Modified polymers The invention includes also a process for producing a modified solid polymer which comprises admixing a normally solid polymer with an ester of a perfluorochloroaliphatic carboxylic acid in which the ester group is derived from an alcohol containing 1 to 20 carbon atoms. The polymers modified to best advantage by the esters are the normally solid high molecular weight, e.g. above 50,000, resinous thermoplastic and elastomeric polymers derived from fluorine containing olefins containing at least 2 fluorine atoms and not more than 10 carbon atoms per molecule. Those specified are homopolymers of vinylidene fluoride, tetrafluoroethylene, trifluorochloro- or homoethylene, 1, 1-difluoro-, 1, 1, 2 or 3-trifluoro-, 1, 1-difluoro-3-methyl-, p and 2-trifluoromethyl-butadienes, a -trifluoromethyl acrylonitrile, methyl-a -trifluoromethacrylate and phenyl trifluoroethylene and copolymers of the above or of trifluoroethylene, dichlorodifluoroethylene, 3, 3, 3-trifluoropropene, perfluoropropene, or perfluoroisobutene with one another or a comonomer such as vinyl chloride or fluoride, vinylidene chloride, butadiene, n-butyl acrylate or 1, 1, 2, 2-tetrafluoroethyl vinyl ether. The modified compositions are mouldable at a temperature below that which is ordinarily required to mould the untreated polymer. The preferred weight ratio of modifier to polymer is 0,1 : 1 to 1 : 1 and the components may be mixed in dry form or in the presence of water or an organic liquid preferably at 10 DEG -50 DEG C. and, particularly when water is present, in the presence of a peroxide promotor. A list of organic and inorganic peroxides is given. The polymers may be modified, e.g. by treating the polymer emulsion obtained from the polymerizer with a metal salt of a perfluorochloroaliphatic carboxylic acid, e.g. the acid from which the ester modifier is derived, to prevent coagulation and then with the ester modifier. When the modification is carried out in the absence of a peroxide the product is a homogenous blend which may or may not be cross-linked, when a peroxide promotor is used a cross-linked polymer is obtained, this is particularly noticeable when unsaturated esters, e.g. allyl esters are used as modifiers. Examples describe the modification of polytrifluorochloroethylene and trifluorochloroethylenevinylidene fluoride copolymer with various saturated and unsaturated esters. Specifications 711,080, 737,267, 784,727 and U.S.A. Specification 2,559,752 are referred to.ALSO:The invention comprises a hydrocarbon ester of a perfluorochloroaliphatic carboxylic acid in which the hydrocarbon radical has 1-20 carbon atoms and a process for preparing an ester of a perfluoroaliphatic carboxylic acid which comprises esterifying a compound having a perfluorochloralkanoyl group with an esterifying agent having an alcoholic function and from 1 to 20 carbon atoms. In particular the invention comprises esters of the formula: <FORM:0871218/IV (b)/1> where Z represents chlorine or a perhalomethyl radical having a total atomic weight not in excess of 146.5, n is an integer from 2-10 and R represents a substituted or unsubstituted alkyl, alkenyl or aryl radical having no more than 20 carbon atoms; and diesters of the formula: ROOC,CFC1(CF2CFC1)n-2CF2COOR where n is an integar from 2-8 and R is as defined above. The esters may be prepared for example by reacting the acid or acid chloride with the desired alcohol or in certain cases by means of acid, alcohol or ester interchange reactions. The reaction is preferably carried out at 10-100 DEG C. in a solvent such as benzene or an excess of the alcohol and in the case for example, of aromatic alcohols catalysts such as trifluoroacetic acid or chlorosulphonic acid may be desirable. A list of alcohols which may be used is given which includes mono-, di- and polyhydric alcohols of the acyclic (saturated, olefinic and acetylenic), carbocyclic (saturated, unsaturated, aromatic and phenolic) and heterocyclic e.g. glycidol and N-methyl pyridinol, series. Examples describe the preparation of esters derived from trichloro-octafluoro-hexanoic, tetrachloroundecafluoro-octanoic and trichloro-nonafluoro-suberic acid and methanol, propanol, butanol, octanol, octadecanol, pentaerythritol (monoester), pentamethylene glycol, phenol, vinyl alcohol and allyl alcohol. The ethylenically unsaturated esters may be homopolymerised or copolymerised and all the esters may be used to modify the properties of normally solid polymers by improving the flow properties (see Group IV (a)). Trichloro-octafluoro-hexanoic acid chloride and tetrachloro-undecafluoro-octanoic acid chloride are prepared by reacting the corresponding acid with phosphorous pentachloride. Specifications 711,080, 737,267, 784,727 and U.S.A. Specification 2,559,752 are referred to.