Patent GB-386826-A (GB)
Title: Improvements in and relating to articles from synthetic resin compounds and to a method for their manufacture
IPC: C08J3/24
Filed: 1932-03-22
Abstract: Synthetic resin such as phenol artificial resins, phthalic acid-glycerin and urea-formaldehyde resins, with or without fillers is poured or pressed into moulds and hardened by passing electric currents through resistance wires disposed in, on, or closely surrounding it without application of pressure during the hardening process.  Where the articles are so large as to require a plurality of wires, they are included preferably in independent circuits and heated to different degrees so that the drying and hardening proceeds progressively from the interior towards the surface of the article. As applied to the manufacture of a box or tube, a wooden or metal core is covered with a layer of synthetic resin mixture one centimetre in thickness.  Resistance wire is then wound round the whole, the coils being one cm. apart.  An additional layer of synthetic resin then is applied and covered with wood, linen, or paper to hold it in position.  The resistance wires then are heated to 50-60 DEG  C. from twelve to twenty-four hours.  The cover finally is removed and the heating continued for a short time afterwards. Smaller articles may be pressed in a mould and then covered with plates around which resistance wires have been wound previously.  The resistance wire may serve as a reinforcement in the finished product. In the Specification as open to inspection under Sect. 91 it was stated that metallic powder may be mixed with the resin compound in order to carry the current.  This subject-matter does not appear in the Specification as accepted.ALSO:Synthetic resin with or without fillers is poured or pressed into moulds and hardened by passing electric currents through resistance wires disposed in, on, or closely surrounding it without application of pressure during the hardening process. Where the articles are so large as to require a plurality of wires, they are included preferably in independent circuits and heated to different degrees so that the drying and hardening proceeds progressively from the interior towards the surface of the article.  As applied to the manufacture of a box or tube, a wooden or metal core is covered with a layer of synthetic resin mixture one centimetre in thickness.  Resistance wire is then wound round the whole, the coils being one centimetre apart.  An additional layer of synthetic resin then is applied and covered with wood, linen or paper to hold it in position.  The resistance wires then are heated to 50-60 DEG  C. from twelve to twenty-four hours. The cover finally is removed and the heating continued for a short time afterwards.  Smaller articles may be pressed in a mould and then covered with plates around which resistance wires have been wound previously.  The resistance wire may serve as a reinforcement in the finished product.  In the Specification as open to inspection under Sect. 91 it was stated that metallic power may be mixed with the resin compound in order to carry the current.  This subject-matter does not appear in the Specification as accepted.