| 摘要 |
926,935. Extruding sheets. MONSANTO CHEMICAL CO. May 11, 1960 [May 11, 1959], No. 16592/60. Class 87(2). A method of producing a sheet of foamable thermoplastic material, i.e., a high density sheet which may be easily transported and subsequently foamed in situ, comprises extruding the material through a die the lips of which are not more than 0À06 inch apart and wherein one lip extends in the direction of extrusion by from 0À001 inch to 0À04 inch more than the other lip, conveying the extrusion on a moving support from the edge of the extended die lip transversely past the other die lip and concomitantly cooling at least the supported surface of the extrusion to below the foaming temperature of the material. In Fig. 1 the die lips 10, 14 are separated by 0À012 inch and the lip 14 extends by 0À005 inch. The material 18 is extruded on to a roller 20 cooled internally to maintain its temperature at 70‹F. A further cooled roller 24 may be provided and conveyer rollers 26, 27 feed the sheet to windup rollers (not shown). Additional water spray cooling may be provided. In Fig. 3 the material is discharged on to a cooled stainless steel belt 30. More than one sheet 18 may be simultaneously extruded and the conveying surfaces may be coated with p.t.f.e. |
