| 摘要 |
<p>1,124,886. Heat-treating oriented thermoplastic films. IMPERIAL CHEMICAL INDUSTRIES Ltd. 23 March, 1967 [15 April, 1966], No. 16602/66. Heading B5B. Apparatus for heat-treating an oriented film of a crystallizable or crystalline organic thermoplastic polymer comprises at least one mattsurfaced rotating roll positioned between feed and take-off means for the film, and maintained at a temperature (below the m.p. of the film) which would cause the film to shrink, means being provided to force the film on to at least one of the rolls, and to spread the film uniformly on at least one of the rolls on to which the film is forced. Specified thermoplastics are polyolefins, polyesters and nylons, of which examples are given. The "forcing-on" means may be an electrostatic charge applied, e.g. by means of a charged wire, knife-edge or row of needles, to the side of the film not in contact with the roll, which is earthed, or may be the tension in the film, especially when small rolls, e.g. of 6 inch diameter are used. In this case the matt rolls may be idler rolls. The spreading means may be a banana or bow roller, or may be a soft material pressing on the film, when it is on the matt roll(s), e.g. a polyether foam coated idler roll. The feed and take-off means may be conventional nip-rolls, with, e.g. three matt rolls between them (as in Fig. 1, not shown). The matt effect may be provided by grit-blasting of, e.g. mild steel, cast iron or aluminium rolls, or may be matt paint. In passing from successive rollers, the speed of film travel is reduced to allow shrinkage.</p> |
