GB946384A - Improvements in and relating to polymers - Google Patents

Abstract

A modified homopolymer of an alpha-monoolefine or a modified copolymer thereof with either at least one other polymerizable monomer containing the CH2=C< radical or carbon monoxide is produced by heating said homo- or copolymer having a molecular weight of at least 10,000 with a modifying agent which is an organic carboxylic acid or an acid anhydride or acid ester derived therefrom at a temperature from 225 DEG C. to 400 DEG C. under autogenous pressure for 0.5 to 10 minutes. The modifying agent may be a saturated or unsaturated aliphatic monocarboxylic acid having from 2 to 6 or 3 to 6 carbon atoms respectively, e.g. acetic, propionic, butyric, valeric, caproic, acrylic, crotonic and sorbic acids or an anhydride or ester of such acids, the alkyl esters having from 1 to 6 carbon atoms in the alkyl chain. Unsaturated aliphatic dicarboxylic acids having from 4 to 8 carbon atoms may also be used e.g. maleic, tetrahydrophthalic, fumaric, glutaconic and itaconic acids or their anhydrides or alkyl esters having from 1 to 6 carbon atoms in the alkyl chain. Phthalic anhydride or pyromellitic anhydride may be used. Copolymerizable monomers mentioned are butene-1, propylene, ethyl acrylate, vinyl acetate, methylmethacrylate, divinyl ether, acrylic acid and bicyclo [2.2.1]-2-heptene. The amount of modifying agent is preferably from 0.25 to 10% by weight based on the combined weight of polymer and modifying agent. The homo- or copolymer and modifying agent may be blended in an extruder and then passed into a reaction zone or the reaction may be carried out in the extruder; alternatively the molten modifying agent or a solution of the modifying agent may be added to the molten polymer as it leaves the extruder. The modified polyolefines may be cured by heating from 50 DEG to 180 DEG C. to produce cross-linked polymers. Modified polyethylene produced by the invention may be vulcanized, for example, by heating 100 parts of the resin with 40 parts of PbO and 3 parts of mercaptobenzothiazole at 150 DEG C. and 250 p.s.i.a. for 30 minutes; or plaques of it may be dyed or it may be used to coat steel, paper, "Cellophane" and "Mylar". (Registered Trade Marks).ALSO:Steel, paper, "Cellophane" and "Mylar" (Registered Trade Marks) can be coated with a modified homopolymer of an a -mono-olefine or a modified copolymer thereof with either at least one other polymerizable monomer containing a CH2=C< radical or carbon monoxide, said modified homo- or co-polymer being prepared by heating the homo- or co-polymer having a molecular weight of at least 10,000 with a modifying agent which is an organic carboxylic acid or an acid anhydride or an acid ester derived therefrom, at a temperature from 225 to 400 DEG C. under autogeneous pressure for 0,5 to 10 minutes (see Division C3). For example a smooth adherent, continuous, coating of a maleic anhydride modified polyethylene may be formed on a mild steel specimen by dipping the latter in a hot 10% solution of the resin in toluene and baking to remove the solvent.