GB839453A - Improvements in or relating to protective helmets - Google Patents

Abstract

839,453. Moulding protective helmets. GENERAL TEXTILE MILLS Inc. May 9, 1956 [May 9, 1955], No. 14339/56. Class 87(2). [Also in Group VII] A protective helmet comprises a non-metallic inner shell 36, at least one layer of unimpregnated multiply fabric 20, 28 and a non-metallic outer shell 18. The shell 18 and 36 are formed by impregnating a fibrous material, such as a glass mat, with a synthetic resin. The fabric is a Iminanar material such as is described in Specification 796,147. The impregnating material is a thermoplastic such as polyethylene, alkyl plastic, polystyrene plastic, phenol formaldehyde compound, urea formal. dehyde resin, or the like. Alternatively the outer shell may be formed of an expanded plastic material such as vinyl resin plastic. Three methods of making the helmet are described. The outer shell 18 may be preformed and one or more layers of fabric 20 and 28 placed within it. A film 34 of non-adherent material, such as cellophane or aluminium foil, is then placed over the fabric, a mat of fibrous resin impregnated material is placed over the non adherent-film and cured to form the inner shell 36. In another method, layers 78 of the fabric protected on either side by films 76 and 80 of non-adherent material are placed between two outer layers 66 and 82 of resin impregnated fibrous material and cured in a heated mould 68 and 70. In yet another method, the inner and outer shells are both preformed and are bonded around their peripheries with plastic material after the fabric has been inserted between them. For this, the two shells may be preformed as in the second method but using a dummy filling between the non-adherent layers and preventing the edges of the shells from bonding together. Spaced holes may be made in the non-adherent films to allow small columns of resin to link the fabric to the shells, Fig. 4 (not shown)..