| 摘要 |
PURPOSE:To perform uniform high speed casting in a method for casting the molten polyester polymer extruded from a molding die while bringing the same into contact with the surface of a cooling body, by forming a specific liquid film of water to the surface of the cooling body. CONSTITUTION:A specific liquid film of water means a film wherein each of specific substances represented by formulae (a)-(d) is interposed in water. Said substances are soluble in water in an extremely small amount but may be uniformly dispersed in water and used alone or as a mixture of two or more kinds of them. The concn. of each of these substances is 0.001-30wt.%, pref., 0.01-10wt.%. When said concn. is below 0.001wt.%, a water film can not be applied uniformly and, when the concn. exceeds 30wt.%, each of the substances is bonded to the surface of a film in large quantities and the physical properties of the film are made inferior and productivity is lowered, because the film is ruptured when stretching is performed. The thickness of the liquid film is 1.0-200mum and pref. 2.0-100mum. When the thickness is below 1.0mum, uniform coating is difficult and, when exceeds 200mum, water is boiled at a place where a melt is contacted and an uneven flaw is generated on the surface of the film. |
