| 摘要 |
<p>A moulded article of a heat-hardening resin or foam, with a special surface layer, is prepd. by (a) pre-heating, to above the hardening temp. of the resin of foam, an agent for forming the special surface layer, esp. a very reactive casting resin compsn.; (b) introducing this into the mould, in a liquid state, to (partly) fill the mould; and (c) cooling the surface-forming agent and heating the walls of the mould, so that the surface-forming agent gels on the walls to form a layer of defined thickness and (partly) coats the walls. Process further comprises (d) removing from the mould the remaining liquid agent; and (e) charging the mould with a synthetic resin or foam compsn. During the exothermal reactions in the mould, the surface-forming agent which has gelled on the walls is briefly heated and fuses with the synthetic resin or foam. The moulded articles are esp. used in high tension switchgear, esp. those exposed to harmful effects e.g. moisture, heat, sunlight, impact, acids, alkalies or corrosive gases. The surface coating is applied during the prodn. of the moulded article, avoiding a separate step.</p> |
