| 摘要 |
<PICT:0688637/III/1> Sheets are coated by extruding a molten film of a normally solid synthetic linear polymer of sharp melting-point to contact with the sheet while still in a molten condition, pressing the film against the sheet and substantially simultaneously chilling the surface of the film remote from the sheet to a temperature below its solidification point. A sheet 3 of molten polymer may be extruded through the slit-like orifice of the die 2 into the nip 6 of the rolls 4 and 5, rotating in opposite directions. The roll 4 may be provided with steam coils or other heating means, and the roll 5 be equipped for cold water circulation. The roll 4 may have a surface of metal or of a compressible material, e.g. rubber, while the roll 5 is normally of metal; its surface may be smooth or embossed. Sheet material 7 is fed from a supply 8, and either around part of the roll 4, or directly into the nip 6, where it contacts the molten film 3, around part of the roll 5, over a roll 9 and to a storage roll 11. The film may be formed of ethylene polymers, chlorinated ethylene polymers or polyamides such as polyhexamethylene adipamide, polyesters, polyester-amides, polyanhydrides and polyethers, or mixtures of polymers or copolymers. Modifiers such as softeners, plasticizers, fillers, pigments, dyes, opacifiers, heat- and light-stabilizers, antioxidants and lubricants may be included. The coatings may be applied to fibrous materials such as paper, wood veneers, woven or knitted fabric composed of fibres of natural or regenerated cellulose, nylons, cellulose derivatives, synthetic resins, asbestos and glass, or non-fibrous materials such as regenerated cellulose sheets, metal foil or sheet and thermoplastic films. In an Example (Example III), a thin aluminium foil backed with paper is coated with an ethylene polymer, the coated foil being subsequently stripped from the paper backing. One side of a sheet of paper may be coated with an ethylene polymer, and the other side with the same or a different thermoplastic polymer. Specification 601,713, (Group VIII), is referred to. |
