GB712408A - Improvements in or relating to polyisocyanate modified polyester resins - Google Patents

Abstract

A reinforced resin or resin foam is made by reacting a mixture of a polyester resin and short organic fibres containing amide groups with an organic polyisocyanate. Reaction is performed in an open vessel to produce a foam and under pressure to produce a dense foam or a solid resin. Specified fibres are nylon, wool, silk, rabbit hair and casein fibre. The fibres preferably have a length of 5 to 10 times their diameter and a length of 0.01-10.0 mm. The polyester is preferably derived by reacting (1) one or more dibasic acids, e.g. adipic, phthalic maleic, sebacic, methylenedisalicylic, tetrachlorophthalic, itaconic, oxalic or diglycolic and preferably a mixture of an aryl dibasic acid and an alkyl dibasic acid with (2) one or more aliphatic polyhydric alcohols, e.g. glycol or polyethylene glycol but preferably an alcohol containing three or more hydroxyl groups, e.g. glycerol, sorbitol, mannitol, pentaerythritol, trimethylolpropane or trimethylolethane. The polyester may also be prepared by reacting (1) a tribasic acid, e.g. tricarballylic, citric, camphorinic, aconitic or trimesic with (2) a diol, e.g. ethylene, diethylene- or propylene glycol. The length of the polyester chain may be controlled by modification with (1) a mono-basic acid, e.g. formic, acetic, propionic, butyric, valeric, caproic, enanthic, caprylic, pelargonic, capric, lauric, benzoic, lactic, sorbic or an unsaturated acid or with (2) an aldehyde e.g. formaldehyde, acetaldehyde, butyraldehyde, propionaldehyde, 2-ethylbutyraldehyde, 2-ethylhexaldehyde, glyoxal, pyruvicaldehyde, acrolein crotonaldehyde, 2-ethyl-3-propyl-acrolein, benzaldehyde or furfuraldehyde. Specified polyisocyanates are toluene di-isocyanate and methylene-bis-4-phenylisocyanate. Reaction between the polyisocyanate and polyester may be performed in presence of water, amines, alkalies, acetone or aluminium powder. In examples the polyester forming reactants are heated to 200 DEG C. whilst removing the water of reaction. The polyester is cooled to 160 DEG C. mixed with 1-400 per cent. of its weight of the fibres and cooled to room temperature. The polyisocyanate is then added and the mixture allowed to react or caused to react by gentle heating. The resulting products are cured by heating to 65-121 DEG C. over a period of hours.