| 摘要 |
A mouldable composition consists of feltable fibrous material mixed with an equal or somewhat greater weight of non-feltable fillers, and a thermoplastic binder dispersed in water, the fibre content being not more than 35 per cent by weight of the finished article, and the proportions being such that in the absence of the thermoplastic substance, a form-sustaining sheet could not be formed. Suitable fibres are wood pulp, animal hair, leather, asbestos, or mixtures of these; fillers comprise rosin powder, cork, sawdust, rubber dust, mineral pigments, etc.; the dispersion may be one of asphalt, pitch, tar, resins, rubber, such as those described in Specifications 244,135, [Class 140, Waterproof &c. fabrics], 315,839, [Class 70, Indiarubber &c.], and 343,427, [Group III]. Vulcanizing agents may also be added. According to an example, 360 parts of paper, and 90 parts of soft leather are mixed with 200 parts of asbestine, 200 parts of yellow clay, 100 parts of sawdust, and 10 - 15 parts of bone black, and 500 parts of asphalt dispersed in water, are mixed in a beater, and 15 parts of soda ash, 20 parts of sodium silicate, and 60 parts of alum are added to break the dispersion. The stock is transferred to a cylinder machine and formed into a web which is formed into sheets of the desired thickness. Rubber dust, Portland cement, or plaster of Paris may be dusted on to the web during the formation of the sheet. The sheet is dried and calendered, and is then moulded or embossed by hot dies. |
