| 摘要 |
1468577 Extruding channelled ceramic W R GRACE & CO 24 April 1974 [25 April 1973] 17957/74 Heading B5A Collapse of the bore or bores or an extruding tube of material, comprising a sinterable ceramic powder and a thermoplastics binder, is prevented by a pressure within the bore or bores provided by a gas evolved at the extrusion temperature from a blowing agent incorporated in the material. After removal of the thermoplastics by burning, the ceramic is sintered to a porous structure which can be used as a support for a catalyst, for the exhaust gases of an internal combustion engine. The material preferably comprises, by volume, 5-70, and preferably 5-50% of polyolefin; 5 to 80, and preferably 20-60% of a preferably water soluble plasticizer; 45 to 80% of cordierite or other ceramic powder; and 0À05 to 2, and preferably 0À1 to 0À5% of the blowing agent. The ceramic may also comprise alumina, mullite, or alumina spinel. The gas may be evolved from pentane, hexane, heptane, low boiling hydrocarbon oils, chlorinated hydrocarbons, azobisformamide, or a volatile component of a plasticizer oil or of the polyolefin. In the examples; (1) and (2), a material comprising linear polyethylene, cordierite, and mineral oil containing volatiles, was mixed at 15‹ C. and then extruded at 350‹ F. in the Fig. 2 configuration and cut into “ inch long pellets which were immersed in trichlorethylene to remove the plasticizer, followed by drying, burning off of the polyethylene, and heating at 1400‹ C. to sinter the cordierite; (4), low density polyethylene containing azobisformamide was extruded in the Fig. 4 configuration. |
