GB1444163A - Polyester films - Google Patents

Abstract

1444163 Polyester films TEIJIN Ltd 9 Oct 1973 [9 Oct 1972] 47101/73 Heading B5B [Also in Division C3] A weather and heat-resistant polyester film comprises a blended mixture of (a) 99À9-51À0% wt. of a polyethylene terephthalate resin and (b) 0À1-49À0% wt. of a naphthalate polyester resin, the film having a softening point at least 1‹ C. higher than its level-off softening point. Resin (a) may be a homopolymer of ethylene terephthalate which may be modified with not more than 15 mol. per cent of other polyesterforming components, and preferably has an inherent viscosity of at least 0À40. Resin (b) may be a homopolyester of naphthalene-2,6- dicarboxylic acid and a dihydric alcohol, e.g. polyethylene 2,6-naphthalat-, or one modified with not more than 15 mol. per cent of other polyester forming components, and preferably has an inherent viscosity of at least 0À35. Optional additives include a delustring agentsuch as TiO 2 or Al 2 O 3 , a stabilizer such as phosphoric acid, phosphorous acid or an ester thereof, a slippery agent such as finely divided silica or clay, an antioxidant, a fluorescent brightening agent, a pigment or dye, a polyamide, polyolefin or another polyester. The film can be made by melt-blending resins (a) and (b) at a temperature of 260‹-330‹ C. for 1-120 minutes and then extruding the mixture into a film. The film may be uni- or bi-axially oriented by stretching to 2-6 times its original length at a temperature ranging above the glass transition temperature of the unstretched film to 160‹ C. in at least one of the extrusion directions and a direction across the extrusion direction. The resulting stretched film may be heat-treated at a temperature ranging from 150‹ C. to the melting temperature of the film under conditions which do not allow free shrinkage of the film. Uses.-Greenhouses; outdoor signboards; electrical insulating material; magnetic recording films; and as fabricating, packaging, tape, decorative or photographic films.