| 摘要 |
Moulded articles are made from a composition of polyethylene terephthalate and 10 to 50% by weight of the article of glass fibres having an average length of at least 0.3 mm. (preferably 0.3 to 8 mm.) and preferably having a diameter of 5-13 m . The composition may also contain 0.1 to 3% by weight, based on the resin, of a nucleating agent which is an oxide, sulphate, phosphate, silicate, oxalate, stearate, benzoate, salicylate or tartrate of a Group II metal; a neutral clay, a carbon powder (e.g. graphite or carbon black); or a mixture of one of these, and titanium dioxide. The polyethylene terephthalate may include other copolymerizable components (e.g. isophthalic acid, 2:2:4:4-tetramethylcyclobutanediol-1:3, 1:4-cyclohexanedimethanol or p-hydroxybenzoic acid) or may be used in admixture with other polymers (e.g. polyethylene isophthalate). The moulding composition may be made by (a) coating glass strands or roving with molten polyethylene terephthalate and then cutting the strands or rovings into suitable lengths or (b) mixing solid polyethylene terephthalate with glass fibres cut into suitable lengths or with ground milled fibres and then melting and extruding the mixture and cutting the extruded product into chips or pellets. The glass fibres may be treated with a silane or given the Volan treatment. Moulding of the composition is usually effected by injection, transfer or extrusion moulding at 120 DEG to 200 DEG C. The properties of the moulded articles are improved by heating them at 120 DEG to 200 DEG C., preferably for 10 to 40 minutes. |
