GB1288284A - - Google Patents

Abstract

1288284 Reinforced plastic tubes KUBOTA IRON & MACHINERY WORKS Ltd 27 Nov 1969 58119/69 Heading F2P A composite tube comprises inner and outer layers of helically wound glass fibres impregnated with thermosetting resin, and an intermediate layer of plastic mortar (resin mixed with sand and/or other low cost additives), at least one of the layers being reinforced with an axially-reinforcing tubular network. In one preferred method for producing the tube a cellulose film or a coating of a release agent is applied to a mandrel, a gel layer is then applied followed by a flexible tubular network 1, Fig. 1 and (Fig. 3, not shown) of axial glass fibre works and circumferential elastic woofs or (11, Fig. 4, not shown) of diagonally arranged glass fibre works and woofs inclined at about 20 degrees to the longitudinal axis. Glass fibre threads 2, impregnated with thermosetting resin are then wound helically on the surface of the tubular network to complete the inner layer A. Layer A is surrounded with a tubular mould (8, Fig. 5, not shown), and the annular cavity filled with plastic mortar comprising 100 parts unsaturated polyester resin, less than 20 parts styrene monomer, from 100 to 500 parts of a mixture of CaCO 3 and silica powders, and, if desired, up to 100 parts of reinforcing fibres such as glass fibre. The plastic mortar is then fully or half cured to form the middle layer 3, and covered with an outer layer B equivalent to inner layer A. The tube is then heated to cure the thermosetting resin and bind the three layers together. In a second method the flexible tubular glass fibre networks are omitted, and a tubular reinforcement composed of axially extending parallel iron bars (6, Fig. 2, not shown) or deformed steel wire, and helical turns of iron wire (61) is concentrically positioned in the annular cavity of the mould, and encased in plastic mortar added to form the middle layer.