GB501649A - Improvements relating to the reinforcement of synthetic resinous materials and objects - Google Patents

Abstract

501,649. Moulding reinforced synthetic resin. BRUYNE, N. A. DE, AERO RESEARCH, Ltd., and DE HAVILLAND AIRCRAFT CO., Ltd. Aug. 26,1937, Nos. 23434/37 and 9941/38. [Class 87(ii)] Reinforced synthetic material or objects having a large dimension relative to the crosssection, such as planks or rings, are made by placing lengths of resin-impregnated flax or linen rove in a mould that is kept hot as a whole or for a substantial part of its length for a certain time, and applying localized pressure for a less time, or transiently until the whole of the contents have been subjected to pressure. The compressed material or object is finally hardened in the mould by heat without pressure. In the form shown in Fig. 2, lengths of flax or linen rove that has been impregnated with phenol-formaldehyde resin and dried on a square-section openwork drum, is placed in a long open-topped mould 4 beneath a sheet 22 of steel. The mould is traversed step by step through a press having a heated platen 10 or plunger and a heated bed. The sides of the mould are protected from being forced outwardly by wedge members carried by the platen 10 and co-operating with inclined walls of the heated bed. In another form, the mould 31, Fig. 9, is placed in a heated member 32 and the material 30 is compressed beneath a flexible steel sheet 44 by a roller 34 of a weighted truck 35 guided on rails 38. Specification 470,331 is referred to. According to the first Provisional Specification, synthetic resin binder is used in such quantity that little excess is squeezed out of the impregnated material during the hot pressing operation. The resin may be applied in a volatile solvent. In some cases, impregnated threads are drawn through heated dies to remove the excess binder, or the excess may be taken up by interspersing unimpregnated material with the impregnated material. In other cases, threads are drawn through a small bath of fused resin binder and thence through a comb to remove the excess. Such threads are then formed into tapes by drawing them through a heated slit. Slivers may be encased in a metal gauze or perforated support during impregnation and drying, or the fibre, before going into the drawing frame, may be impregnated, and, as it leaves the frame, pressed by heated rolls. According to the second Provisional Specification, the trough in which the material is moulded may be jacketed for heating-fluid, and may be lagged with heat-insulating material. As impregnated rove is laid in the trough, further resin may be packed in.