| 摘要 |
<p>1485776 Foamed, skinned photopolymerized polymers IMPERIAL CHEMICAL INDUSTRIES Ltd 30 Dec 1974 [10 Jan 1974] 01190/74 Heading C3C An article is made by forming a foamable mixture of a photopolymerizable ethylenically unsaturated material and a foaming agent in a mould which is constructed of suitable material to permit irradiation of the mixture, subjecting at a temperature, which at least initially, is below the temperature at which foaming of the mixture occurs, at least a part of the surface of the mixture to radiation of wavelength such that photopolymerization of the material occurs to form a non-foamed and non-foamable skin layer or layers and then foaming the foamable mixture and upon completion of the foaming polymerizing the ethylenically unsaturated material in the foam. In the examples a mixture of unsaturated polyester resin, clay or glass fibres, ammonium bicarbonate, foamstabilizer, tert. butyl perbenzoate, dimethylaminoethanol (reducing agent for the photosensitizer) and benzil, (as photosensitizer) and optionally pigment were poured into a mould having glass sides, irradiated to form a gelled surface layer and heated to foam and cure the resin.</p> |
