Polyester film prepn. for improved colour tone for high productivity - by adding inorganic lubricant comprising alkylene glycol slurry, potassium cpd. and phosphorus cpd. to poly:alkylene terephthalate!

摘要

Prepn. of master polymer for producing film comprises: (i) adding: (A) an inorganic lubricant comprising: (a1) alkylene glycol slurry; (a2) a potassium cpd.; and (a3) a phosphorus cpd., in an amount satisfying equations (1)-(3) to: (B) polyalkylene terephthalate oligomer having an average degree of polymerisation (Dp) of 10 or less for 30 minutes or more; and (ii) adding antimony trioxide and germanium dioxide in an amount satisfying equations (4)-(6); 5 X 10-4 = a = 50 X 10-4 (1) 2.5 X 10-4 = b = 25 X 10-4 (2) 0.15 = b/a = 1.5 (3) c = 2.5 X 10-4 (4) 0.5 X 10-4 = d = 5 X 10-4 (5) 2.5 X 10-4 = c + d = 5 X 10-4 (6) a, b, c, d = mol of each cpd. added per mol of the acid component in the oligomer; a = amount of potassium cpd.; b = amount of phosphorus cpd.; c = amount of antimony trioxide; and d = amount of germanium dioxide; where: (1) prepn. of polyester film comprises: (A) fusion-mixing: (i) 3-12 pts.wt. of the above master polymer contg. 0.3-3 wt.% of (A); and (ii) 97-88 pts.wt. of polyalkylene terephthalate having a limiting viscosity of 0.5 or more; and (B) film-forming by an electrostatic casting method.