| 摘要 |
767,957. Rubber compositions. DURIE & MILLER, Ltd. Oct. 25, 1954 [Nov. 16, 1953], No. 31750/53. Class 70. [Also in Group VIII] A porous sheet material consists of particles of organic granular material linked together by local adhesion to present a large number of intercommunicating cavities open to the atmosphere some of the cavities having a volume which is very much larger than the volume of any of the particles of material. The material may be prepared by foaming a mix comprising a foamable aqueous solution or suspension of an adhesive mix of natural rubber latex or synthetic resin and a granular organic material in the proportion of 2 to 14 parts by volume of granular material to 1 part of total dry rubber or resin content of the solution or suspension, and drying a layer of the foam under such conditions that envelopes enclosing the air bubbles in the mix are destroyed before the granules have an opportunity of settling. In an example a rubber latex mix is prepared by mixing in a mixer 1, Fig. 3, in parts by weight: concentrated rubber latex 130, rubber reclaim dispersion 50, sulphur 2À5, zinc diethyldithiocarbamate 0À75, zinc oxide 5, 5 per cent aqueous sodium alginate solution 100, and 10 per cent aqueous casein solution 25. The mix is fed into a vessel 4, where 200 parts by weight of light red rubber crumb are added, and is then foamed by a stirrer 6. The vessel 4 is tilted to deposit the batch 9 on a backing 8, e.g. of hessian, to be spread by a spreader 10 and passed into a heated drying chamber 11 where it is slowly dried, e.g. at a temperature of 95‹ to 105‹C., in a moist atmosphere. After drying the material is trimmed by knives 13 and wound into a roll 15. In an alternative embodiment the rubber latex mix comprises 58À9 kgs. concentrated rubber latex, 24À95 kgs. black rubber reclaim dispersion, vulcanizing, filling and preserving ingredients, sodium alginate and casein. To this mix is added 60À6 kgs. of granulated cork, and a sheet material is prepared as described above. The backing may, alternatively, comprise cotton scrim, paper, nylon fabric, or impermeable synthetic resin or leather material, or the backing may be omitted from the finished product, the mix being spread on a support such as wire gauze from which it can be stripped when dry. The granular material may also consist of sawdust and the binding material may comprise synthetic rubber latex or a suspension of reclaimed rubber or of synthetic resin such as polyvinyl chloride or acetate. Specification 414,814 is referred to. |
