GB1159579A - Fiber Molding Pellets - Google Patents

Abstract

1,159,579. Reinforced mouldings. F. H. HUMPHREY. 5 Dec., 1966 [6 Dec., 1965], No. 54424/66. Heading B5A. [Also in Division D1] A pellet for use in moulding reinforced plastics articles comprises fibres which have been elastically flexed and a binder which restrains the fibres from unflexing and which loses its binding effect during the moulding so that the fibres unflex and distribute themselves in random directions. The pellets may be formed by twisting two bundles of glass filaments together, applying a binder before or after the twisting, setting the binder-for example using an oven-and cutting the twisted strand into pellets. Alternatively, untwisted glass filaments may be cut into short lengths which are subsequently bent double and restrained from unbending by a binder. The binder may be polyethylene which melts during the moulding, or a polyester or polystyrene resin which dissolves in liquid unsaturated polyester resin from which the article is moulded. The moulding may be carried out by pouring the resin over the pellets in a mould from which air may have been evacuated, by dropping the pellets into the resin in a mould, or by mixing the pellets with a powdered plastic. Pipe fittings, valve bodies, pump parts or machine components may be cast. Pipes may be made by feeding pellets using pneumatic, screw, or vibrating conveyer systems to the inside of a rotating mould in which liquid resin has previously been deposited. In a specific example, a hollow sphere was formed by adding 80 parts by weight of liquid unsaturated polyester resin which had been catalysed and 20 parts by weight of the pellets to a spherical mould which was rotated about two axes by a gimbal arrangement.