| 摘要 |
1486849 Laminated films W R GRACE & CO 22 Dec 1975 [23 Dee 1974] 52449/75 Headings B5N and B5B A process for producing a laminate of polymeric films comprises: (a) forming a laminate by co-extruding a film of a nylon having a second order transition temperature of below 150‹ F. and optionally being in the form of a plurality of contiguous layers of nylon with an adjacent substantially water-impermeable layer or layers of at least one other kind of polymer which is orientatable at a temperature below 150‹ F. into laminar relationship with one or both of the main surfaces of the nylon film, (b) quenching the extruded laminate to a temperature below the second order transition temperature of the nylon and (c) heating the laminate to a temperature above the second order transition temperature of the nylon and at which the adjacent layer or layers are orientatable, but below 150‹ F. and stretching the laminate while so heated, to orient the nylon and said other polymer, the process up to the beginning of step (c) being carried out so as to protect the nylon film from substantial contact with water. The nylon may be a polyamide, e.g. nylon-6 or a co-, homo-, block or graft polyamide, the other polymer being preferably polyethylene or an ethylenevinyl acetate copolymer. In the method described with reference to Figs. 1 and 2, nylon from extruder A and olefin polymers from extruders B and C are fed to annular co-extrusion die 1, the inner ply coming from extruder B, the central ply from extruder A and the outer ply from extruder C. A tubular laminate 4 emerging from die 1 is cooled by cooling ring 5 and collapsed between pinch rollers 6 in cooling bath 7 to form flattened tubing 9 which is fed across guide rolls 8 and wound on roll 10, no water having contacted the nylon film thus far in the process. The roll of flattened tubing 10 is then unwound and fed through pinch rolls 12 into heated bath 13, thence over guide roll 14 and through pinch rolls 15 where it is expanded into bubble 16 by the trapped bubble technique, the resultant stretched laminate passing over roll 18 to wind-up roll 19. In an alternative procedure, the laminate made by co-extrusion through a slot die with the nylon layer sandwiched between two adjacent layers, stretch orientation being effected uniaxially by racking. Example I describes the manufacture of a sixply laminate comprising layers of polyethylene, an ionomeric ethylene copolymer, nylon, nylon, an ionomeric ethylene copolymer and polyethylene. |
