| 摘要 |
1,130,024. Shrinkable films. W. R. GRACE & CO. 10 May, 1967 [11 May, 1966], No. 20975/66. Heading B5B. [Also in Division C3] A biaxially oriented film comprises a vinyl chloride polymer which has a Young's modulus of elasticity of at least 200,000 p.s.i. (14,000 kg./cm.<SP>2</SP>) at 23‹ C. in both directions, a shrinkage of up to 35% at 100‹ C. in both directions and a shrink tension less than 150 p.s.i. (10À5 kg./cm.<SP>2</SP>) at any temperature. The films may also contain conventional additives, stabilizers and lubricants, and are used for shrink packaging of articles such as boxes, and jacketed records. The films may be obtained by (a) extruding a melt of vinyl chloride polymer through an annular extrusion orifice, and after cooling the tubular extrudate, biaxially orienting the tubular extrudate to the desired degree. |
