Patent GB-897313-A (GB)
Title: Embossing thermoplastic film
IPC: B32B27/00
Filed: 1959-04-01
Abstract: 897,313. Laminates and laminating. CARPENTER CO., L. E. April 1, 1959 [April 4, 1958], No. 11095/59. Class 140. [Also in Group XVI] A method of making an embossed thermoplastic film, or a laminate comprising such a film comprises heating a sheet of thermoplastic material substantially thicker than the film to a temperature above the softening points of the material and of the film, bringing one surface of the film into contact with a surface of the heated sheet and thereby transferring to the film sufficient heat to soften it, embossing the film and sheet together with an embossing element and thereafter cooling the sheet and the film. As shown in Fig. 1, the film 1 e.g. of polyethylene terephthalate, polyvinyl chloride or polyethylene not more than 0.003 inch thick, is fed from a reel 2, round an expander roll 3 and over the periphery of a cooled embossing roll 4 which cooperates with a counter-roller 5. A web 6 comprising a backing of cotton duck or the like covered with a layer of a polyvinyl chloride dispersion about 0.020 inch thick is fed from a reel 13, round idler rollers 14, 15 and through an infra-red heater 17. As the web 6 passes round the roller 15 it is coated by an atomizer 16 with an agent, such as an emulsion of silicone oil with water, which will facilitate separation of the webs 1, 6. The web 6 is heated to 400‹ C. in the heater 17 and on emerging therefrom is passed, together with the film 1, between the embossing roller 4 and counter-roller 5 whereby the film 1 is heated by contact with the web 6 and the film and the underlying web are both embossed with the design of the roller 4. After embossing the film and web travel together until they are cool ; they may then be separated and taken to their respective take-up reels 9, 10. The embossed pattern on the web 6 may be removed by reheating or the thermoplastic coating on the web may have a " short term memory " so that the pattern embossed thereon disappears after a short time. If a laminated product is desired the step of spraying the web 6 at 16 is omitted and the materials of the film and the web are selected from those which will stick together under the influence of heat and pressure. The web 6 may be in the form of an endless belt e.g. of thermoplastic rubber on a woven glass backing. The belt returns quickly to its original smooth contour after the embossing. The apparatus of Fig. 2 produces a laminate having printed and embossed designs in registry thereon. A thin thermoplastic film 20 is fed from a reel 21 round an impression roller 23 where it is printed by a printing cylinder 22. After leaving the impression roller 23 the film 20 is brought into contact with a web 27 and is embossed therewith between an embossing roller 26 and a a counter roller 33. The web 27 comprises a backing of cotton duck which is wound off a reel 28 past a coating device 29 which deposits thereon a thermoplastic coating. A heater 30 heats the web 27 to a temperature well above the softening temperature of the thermoplastic coating and also above that of the film 20. After the embossing operation the composite web 34 is cooled and wound on to a take-up spool 35. The embossing roller 26 and the printing cylinder 22 have the same diameters and are driven in synchronism. The length of film 20 between the bite of the printing rollers and the bite of the embossing rollers is a multiple of the circumference of the printing cylinder so as to ensure registration of the printed with the embossed design. Instead of forming a laminate therewith the film 20 may be stripped from the web 27 after the embossing operation, as shown in Fig. 1, in which case the web 27 may be in the form of an endless belt. In a modification of the Fig. 2 process the printed side of the thermoplastic film is secured to the thermoplastic web coating during the embossing operation, the film being transparent or translucent, so that in the laminated product the printed design is protected from rough usage.