| 摘要 |
PURPOSE:To provide the film with excellent light beam transmittance as well as desired thin and flexible property, prevent the strain or buckling or leg between two layers of film and obtain a good temperature-keeping property by a method wherein the inner and outer two layers of tubular film are adhered to the side wall surfaces of inner and outer annular cooling-water tanks by the pressure of gas sent between annular slits and water is passed through both annular water tanks. CONSTITUTION:Molten thermoplastic resin 4, extruded through the delivery port 7 of an extruding dice 1, is formed into two-layer tube, connected by a multitude of legs between two layers, and the tube is inflated with a gas supplied from a pipe 37. The positions of height of a water depth regulating ring 21 for inside annular cooling-water tank and a water depth regulating hollow tubular nut 31 for the outside annular cooling-water tank are adjusted to equalize the depths of water, contacting with both inner and outer layers of the two-layer hollow film, and cool the inflated resin in the inside and outside annular cooling water tanks 2, 3 while the pressure of air, sent by pressure between both annular slits 8, 9 of the dice through an air sending port 11 formed between the same slits 8, 9, is adjusted to adhere both of the inner and outer films to the annular outside wall 12 and the annular inside wall 13. |
