Abstract: A process for preparing a polyamide type film which comprises melt-extruding a polyamide resin having a metal compound and a melt specific resistance of not more than 1.5.times.10.sup.5 .OMEGA.cm at 260.degree. C. in a form of a film, contacting the melt-extruded film closely with a revolving cooling drum through static electricity and taking up the film while cooling rapidly to solidify, which provides remarkable improved adhesion by static electricity. As a result, increasing the take-up rate of the revolving cooling drum does not cause trapping of air between the drum and the film so that a film having excellent uniformity in thickness and transparency can be produced.

Abstract: A thermo-shrinkable polyester film of this invention is obtained from a composition that comprises acid components including terephthalic acid and glycol components including ethyleneglycol. The polyester film has a heat-shrinkage ratio of 30% or more in a certain direction at 100.degree. C., and a shrinkage ratio of 5% or more at the point of intersection of a curve showing the internal shrinkage stress of the film and a curve showing the tensile stress of the film.

Abstract: An oriented polyester film having at least one surface being roughened by containing inactive particles and three-dimensional surface roughness exponents of the said roughened surface are within ranges simultaneously satisfying the following relationships (I) to (III), while the number of coarse projections is in excess of the fourth grade:0.014.ltoreq.S.DELTA.a.ltoreq.0.025 (I)5.2.ltoreq.S.lambda.a.ltoreq.13.0 (II)0.012.ltoreq.SRa.ltoreq.0.050 (III)where S.DELTA.a represents three-dimensional average gradient, S.lambda.a represents the spatial average wavelength (.mu.m) of three-dimensional surface roughness and SRa represents three-dimensional central plane average roughness (.mu.m).

Abstract: An oriented polyester film comprising ethylene terephthalate as the major repeating units, which comprises 0.01 to 1.0% by weight of silica particles and/or titanium dioxide particles having each an average particle size of 0.01 to 0.5.mu. and 0.005 to 1.0% by weight of calcium carbonate having an average particle size of 0.01 to 0.5.mu., which provides an oriented polyester film for the base film of video tape which has a flatness on the surface and has excellent slipperiness, abrasion resistance and running characteristics as well as excellent magnetic transducer characteristics.

Abstract: An improvement in a process for producing an elastic polyester wherein a crystalline aromatic polyester and one or plurality of lactones are reacted, the improvement comprises by carrying out the reaction in a continuous process by continuously feeding the molten crystalline aromatic polyester and the lactones to a reaction vessel to subject them to addition polymerization, while continuously discharging a reaction mixture from the vessel to obtain the elastic polyester. Optionally, the reaction mixture can be further subjected to polycondensation in a molten state or a solid phase.

Abstract: A thermoplastic resin film laminate which comprises a thermoplastic resin film, particularly, a polyester film and a layer of a polyester resin composition provided on at least one surface of the film, said composition comprising(A) a water insoluble polyester copolymer composed of a mixed dicarboxylic acid component containing a dicarboxylic acid having metal sulfonate group in an amount of 0.5 to 15 mol % based on all the dicarboxylic acid component and a glycol component; and(B) inert particles; the weight ratio of (A)/(B)=100,000/0.5-3,000. Optionally, the composition can contain one or more ingredients selected from the group consisting of a water soluble silicone, a polyfunctional reactive compound, a polyethylene glycol and its derivative and an antistatic agent. The thermoplastic resin film laminate is preferably produced by so-called in-line coating.

Abstract: A polyester having an initial accumulation electric charge of not less than 2.9 .mu.c/mm.sup.2 when determined in a melt state according to the method as hereinabove defined and a heat resistance of not more than 0.210 when determined according to the method as hereinabove defined, which comprises at least one magnesium compound and at least one phosphorus compound solubilized therein in amounts as satisfying the following formulas:30.ltoreq.[Mg].ltoreq.400 (1)0.8.ltoreq.Mg/P.ltoreq.3 (2)wherein [Mg] is the content (ppm) of the magnesium compound in terms of magnesium atom to the polyester and Mg/P is the atomic ratio of the magnesium atom in the magnesium compound to the phosphorus atom in the phosphorus compound.

Abstract: An oriented polyester film comprising ethylene terephthalate as the major repeating unit, which comprises particles of kaolinite and calcium carbonate uniformly dispersed therein, said kaolinite and said calcium carbonate having each an average particle size of 0.05 to 0.8 micron and being contained in such amounts as satisfying the following equations:70.ltoreq.D.times.A.ltoreq.1000 (I)1000.ltoreq.A+B.ltoreq.10000 (II)0.1.ltoreq.B/A.ltoreq.25 (III)wherein D is an average particle size (micron) of calcium carbonate, A is a content (ppm) of calcium carbonate and B is a content (ppm) of kaolinite, said oriented polyester film being excellent in flatness, slipperiness, abrasion resistance, etc. with a small number of coarse particles.

Abstract: A process for production of a polyester comprising units of ethylene terephthalate as the major repeating units by supplying terephthalic acid and ethylene glycol continuously or intermittently to bis(beta-hydroxyethyl) terephthalate or its oligomer so as to carry out esterification under a pressure of not more than about 1.0 kg/cm.sup.2, followed by polycondensation, which is characterized in that at least one magnesium compound is incorporated into the reaction system in an amount of about 30 to 400 ppm in terms of Mg to the polyester when the esterification rate in the step of esterification reaches about 20-80% and at least one phosphorus compound is incorporated into the reaction system in an amount as satisfying the following equation (I) at the stage after the esterification rate reaches not less than about 91% and before the termination of the initial condensation in the step of esterification:1.2.ltoreq.Mg/P.ltoreq.20 (I)wherein Mg/P is the atomic ratio of the magnesium atom to the phosphorus atom.

Abstract: A process for producing polyester resins, such as saturated polyester resin, alkyd resin and unsaturated polyester resin from polyester wastes, which comprises depolycondensing polyester wastes with at least one polyol in the presence of at least one titanyl oxalate compound and/or titanium tartrate compound and subsequently polycondensing the resulting depolycondensation product with at least one polycarboxylic acid or its anhydride or with at least one polycarboxylic acid or its anhydride and at least one polyol, optionally in the presence of at least one phosphorus compound.