| 摘要 |
1526722 Laminates O-B RASMUSSEN 27 Aug 1975 [5 July 1974 11 Dec 1974 12 Feb 1975 (2)] 29807/74 53644/74 5971/75 and 5972/75 Headings B5N and B5A A laminating method comprises extruding at at least two layers of molten polymer blend, each of polymers that are incompatible such that on solidification the blend comprises a dispersion of one polymer in a polymeric matrix, attenuating each layer while molten, before, during or after extrusion, to distort the particles in each layer into a fibrillar grain, structure having a predetermined direction of splittability after solidification into a film, bonding the films with said directions transverse to each other, solidifying the layers and biaxially orienting the product on substantially uniaxial steps at a temperature low enough to maintain said directions, the bonding being sufficiently weak to allow local delamination upon tearing. The blends may be polyamide mixtures, iso- or syndiolactic polypropylene and high or low density polyethylene-together with a sticky atactic polypropylene, ethylene propylene rubber or polyisobutylene. Bonding may be effected using adhesive on spots or lines or by applying a release agent in spots or lines. Bonding may be effected using solidified films. In the method shown with reference to Fig. 1, two concentric tubular streams of the blends 1, 2 are rotated in passage through an annular extrusion die while rotating rings 7, 8 to effect attenuation, the streams being bonded in collection chamber 15 and passed molten through exit slot 16. In the method of Fig. 2, the die has fixed inlet 17, fixed bearing 18 supported by rotating members 19, 20 forming exit 21, polymer blend A being extruded through annular conduits 22, 23 and blend B through conduit 24, the resultant streams passing channel arrays 25, 26, 27 to annular chambers 28, 29, 30 respectively, merging in chamber 38 and exiting by orifice 21. In the embodiment of Fig. 3, streams C, D pass from annular conduits 44, 45, 46 through channels 47, 48 respectively into annular chambers 49, 50. In the embodiment of Fig. 4, 60 is a rotating ring formed extrusion die, a blend being fed into circular groove 61 and led by rotating exit slot 62, through channels 63. 65 is a fixed mandrel and 66 a preformed tubular sheet having a longitudinal direction of splittability, the fluid polymer 70 from slot 62 being wound around the sheet.
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