GB763743A - Improvements in method of manufacturing heat insulating hollow articles - Google Patents

Abstract

763,743. Moulding footwear; cellular rubber. UNITED STATES RUBBER CO. May 31, 1954 [July 22, 1953], No. 16043/54. Classes 70 and 87(2). [Also in Group VII] A method of making hollow heat insulating articles such as boots having an outer shell of tough protective flexible waterproof organic plastic and a lining of non-water-absorbent, soft, flexible heat-insulating closed-cell cellular material bonded to said shell comprises in the making of the boot shown mounting a layer 22 cut from a sheet of cellular producing material on an inflatable last 16 having a solid core 18 and a cover 19 and then a similar layer 23 of solid plastic forming material such as vulcanizable rubber compound. The last partially inflated is placed in a mould cavity 28 as shown and the last is fully inflated to force the outer layer into contact with the mould which is then heated to give a partial pre-cure at a temperature at which gas is not generated in the layer 22 and then when the layer 22 is sufficiently flow resistant to confine the gas in the individual or closed cells further heated for a final curing. In addition to boots, gloves and mittens can be made in this way. A compound suitable for the layer 23 is in parts by weight pale crepe rubber 100, whiting 75, carbon black 5, zinc oxide 5, granular asphalt 12, Trimene base (Registered Tade Mark) (accelerator) 0À75, sulphur 2À5. A compound suitable for the layer 22 also in parts by weight is butyl rubber 100, channel carbon black 15, zinc oxide 5, circo oil (light processed rubber softening oil) 15, paraffin wax 2, red lead 0À5, sulphur 3, tetra-methyl thiuram disulphide (accelerator) 1À5, selenium diethyldithiocarbamate (accelerator) 1À5, zinc ammonia nitrite-bentonite paste (blowing agent) 32À3. The latter paste has as components zinc ammonia nitrite 40À0, ammonium hydroxide 6À8, bentonite 20À0.