GB1103236A - Footwear having a polyurethane foam sole and method of making same - Google Patents

Abstract

1,103,236. Boots &c. TOYO RUBBER INDUSTRY CO. Ltd. 9 Nov., 1966, No. 50238/66. Heading A3B. [Also in Division B5] A shoe having a moulded-on sole of polyurethane foam is made by casting or pouring a liquid polyurethane-forming mixture into a mould which is closed by a lasted shoe upper and which is maintained at a predetermined initial temperature, and allowing the liquid polyurethane-forming mixture to foam so that the sole becomes bonded to the shoe upper. The mould consists of a base 10 and split side walls 2 clamped together by bolts 4, 5 and the lasted upper is held in position by a clamp 16 on a frame 18 which is fixed to the mould base by pins 19. The polyurethane-forming mixture may be poured into a preheated mould before it is closed by the lasted upper or may be injected into a preheated mould after the mould has been closed by the lasted upper. The mould may be preheated and maintained at a temperature between 20‹ and 80‹C. depending on the type of foam required, the lower temperatures producing a more rigid foam sole. The sole may be removed from the mould after complete curing of the sole or may be removed after primary curing of the sole, the last being removed from the shoe after secondary curing. Shaped bodies of rubber, synthetic resin or metal may be placed in the mould to produce skidresistant or abrasion resistant soles. The mould may be coated with a release agent or lubricant or may be formed from a material which is easily separable from the polyurethane foam, e.g. polyethylene, polypropylene or polystyrene. Alternatively a mould release film 17 (Fig. 5) of the above synthetic resins may be provided in the mould. The mould release film 17 may be held in position by clamps 14 and may be vacuum formed to the shape of the mould, the mould being evacuated along ducts 6, 7, 8. The examples describe particular polyurethane forming mixtures.