| 摘要 |
A method of manufacturing a porous product having interconnected cells comprises the steps of compressing finely divided plastic particles to a predetermined shape and heating at a temperature sufficiently high to sinter adjoining particles together but sufficiently low to create a reticulated structure within the material, at least 94.8% by weight of the particles ranging from 44 to 297 microns in diameter. A thermally unstable blowing agent may also be included in the mixture. The particles may consist of polyethylene, polyvinyl chloride, epoxy resin, polyvinyl formal or polyvinyl acetate. A typical blend comprises by weight polyvinyl chloride 45%, polyethylene 25% and phenol-formaldehyde 30%. As a specific application a printing roller is made by this process, which is of retaining up to 50% of its weight of ink. In the modification dinitrosopentamethylene tetramine is used as the blowing agent. A typical analysis of particle sizes (% by weight) in the materials to be used is: greater than 297 microns, 0.8%; greater than 149 microns, 20.8%; greater than 74 microns, 62.4%; greater than 44 microns 10.8%; under 44 microns, 4.4%. Specification 754,707 is referred to.
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