Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Patent
1974-11-08
1976-10-12
Thurlow, Jeffery R.
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
264185, 264210R, 264211, 264235, 264290R, 264345, B29D 724, D01D 512, D01F 614
Patent
active
039858499
ABSTRACT:
Method for preparing a biaxially oriented polyvinyl alcohol film by extruding a mixture of polyvinyl alcohol and water, and if desired, incorporated with a polyhydric alcohol, in a tubular form, drying the tubular film to give a tubular non-stretched film having a degree of crystallization of not more than 44 % and a water content of not more than 20 % by weight, and biaxially stretching the non-stretched film at a stretching ratio of not less than 2 in each of the machine and transverse directions by means of inflation under conditions such that the film surface at the starting point of stretching is maintained at a temperature in the range from about 60.degree. to about 150.degree.C., the surface of the film reaching a maximum temperature at the middle portion of a stretching zone extending from said starting point to a point where the tube reaches a maximum diameter and the difference between maximum and minimum surface temperatures in the stretching zone does not vary more than about 15.degree.C. The prepared biaxially oriented film is excellent in tensile strength, dimensional stability and impact resistance at low temperature, and has a tensile strength of not less than 1,200 Kg./cm..sup.2, an elongation of 30 % to 80 % and a Young's modulus of not less than 10,000 kg./cm..sup.2.
REFERENCES:
patent: 3243486 (1966-03-01), Pilaro
patent: 3425979 (1969-02-01), Monaghan et al.
patent: 3440316 (1969-04-01), Miyake et al.
patent: 3607812 (1971-09-01), Takigawa et al.
patent: 3723583 (1973-03-01), Hovermale et al.
patent: 3872196 (1975-03-01), Bridgeford
Notomi Ryohta
Shigeyoshi Tuyoshi
Sugiyama Masayoshi
Kohjin Co., Ltd.
Thurlow Jeffery R.
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