Abstract: A novel high density magnetic recording medium is disclosed. Said medium comprises a polyester film formed of a plurality of layers laminated by coextrusion and oriented by stretching, which simultaneously satisfies the conditions of the following relations (1) to (4); a back coat layer which is provided on the rougher surface side of said polyester film layer and whose surface roughness simultaneously satisfies the conditions of the following relations (5) and (6); and a magnetic film layer provided on the less rough surface side of said polyester film.Ra.sup.A .ltoreq.0.008 (1)0.005.ltoreq.Ra.sup.B .ltoreq.0.02 (2)0.005.ltoreq.Ra.sup.B -Ra.sup.A .ltoreq.0.015 (3)9.ltoreq.F.sub.5 .ltoreq.30 (4)0.015.ltoreq.Ra.sup.C .ltoreq.0.040 (5)0.003.ltoreq.Ra.sup.C -Ra.sup.B .ltoreq.0.35 (6)whereinRa.sup.A stands for centerline average roughness (.mu.m) of the less rough surface side of the polyester film;Ra.sup.B stands for centerline average roughness (.mu.m) of the rougher surface side of the polyester film;Ra.sup.

Abstract: A biaxially oriented polyester film containing a specific calcium carbonate is described. The calcium carbonate contained in the film is specified by its vaterite form, its average particles size of 0.07 to 1.5 .mu.m, and its particle size distribution ratio of not more than 2.00. The biaxially oriented polyester film containing such specific calcium carbonate is excellent in both the running property and wear resistance, and suitable for the use as a base of magnetic recording media.

Abstract: A laminating material for safety glass is disclosed wherein said material comprises a substrate of a polyester film satisfying the following conditions (1) to (4), on one side of which a heat ray shielding layer consisiting of a metal and/or a metallic compound:R.gtoreq.8000 (1)H.ltoreq.5 (2).alpha..sub.MD +.alpha..sub.TD .ltoreq.10 (3)F.sub.B .gtoreq.8 (4)wherein R stands for retardation (nm), H stands for film haze (%), .alpha..sub.MD and .alpha..sub.TD respectively stand for shrinkage of the film in the longitudinal (machine) direction and in the direction perpendicular to said direction and F.sub.B stands for the strength at break point (kg/mm.sup.2) in the longitudinal direction. The laminating material of the present invention does not generate interference fringes by polarized light, is excellent in transparency, heat resistance and strength and, therefore, suitable for heat ray reflection safety glass.

Abstract: A biaxially oriented polyester film simultaneously satisfying the following formulas (I) to (III):.vertline.S.sub.180 -S.sub.120 .vertline..ltoreq.54 (I)T.sub.S.sup.MD .gtoreq.100 (II)Q.sub.120 .ltoreq.0.7 (III)wherein S.sub.180 is shrinking stress (g/mm.sup.2) of the film in the machine direction at 180.degree. C., S.sub.120 is shrinking stress (g/mm.sup.2) of the film in the machine direction at 120.degree. C., T.sub.S.sup.MD is shrinkage initiation temperature (.degree.C.) of the film in the machine direction, and Q.sub.120 is shrinkage (%) of the film in the machine direction after 5 hours' treatment at 120.degree. C., is described. The film has a good dimensional stability due to its low shrinkage, particularly in the machine direction, and substantially free from defect such as wave and wrinkle.It is prepared by biaxially stretching, heat-setting and relaxing an extruded polyester film under particular conditions so as to obtain a biaxially oriented polyester film having these characteristics.

Abstract: A shrinkable copolyester film having shrinkage of not less than 30% in the direction (main shrink direction) of either the machine direction or the transverse direction after 5 min treatment in an air oven at 100.degree. C., a shrinkage of not more than 20% in the other direction perpendicular to the main shrink direction after 5 min treatment in an air oven at 100.degree. C., an initial shrinkage stress (F.sub.0) of not more than 2000 g/mm.sup.2 in the main shrink direction during the course of 5 sec after dipped in a silicone oil of 75.degree. C., a shrinkage stress (F.sub.20) of not less than (F.sub.0 -100) g/mm.sup.2, after 20 sec dipping in a silicone oil at 75.degree. C., and a glass transition temperature of 35.degree. to 65.degree. C., is disclosed. The shrinkable copolyester film of the present invention is excellent in shrinkage properties, i.e., substantially free from wrinkles, distortion of film and uneven shrinkage, and is suitable for a shrinkable label for a PET bottle, etc.

Abstract: A heat-sealable laminated film is disclosed which comprises a heat-sealing layer formed of a copolyester and having a thickness of not less than 5 .mu.m and a base layer formed of a copolyester containing the copolymerized unit common to the copolyester of the heat-sealing layer.The film of this invention excels in heat-sealing strength, is extensively usable in applications for packaging, electric insulation, and industry in general, and has high industrial value.

Abstract: Disclosed herein is a polyester shrinkable film. The film according to the present invention can provide extremely excellent durability and long-time storability of contents of a container in labelling and shrink packaging use.

Abstract: Disclosed herein is a transfer material for use with a printer, which comprises a biaxially oriented polyester film which simultaneously satisfies the following expressions (I) to (III):12.0.ltoreq.F.sub.5 .ltoreq.17.0 (I).sigma..ltoreq.0.06.times.F.sub.5 -0.5 (II)E.sub.p .gtoreq.4.times.10.sup.3 .times..DELTA.n.sub.p +250 (III)wherein F.sub.5 represents the F.sub.5 value (kg/mm.sup.2) in the machine direction of said polyester film, .sigma. represents a heat shrinkage (%) in the machine direction of said polyester film after heat treatment at 100.degree. C. for 30 minutes, E.sub.p represents a Young's modulus (kg/mm.sup.2) in the machine direction, and .DELTA.n.sub.p represents a degree of plane orientation of said polyester film, and a transfer ink layer formed on one surface or both surfaces of said polyester film.

Abstract: Disclosed herein is a magnetic card comprising a monoaxially or biaxially stretched minute-cellular polyester film which has an apparent density of 0.4 to 1.3 g/cm.sup.3 and an opacifying power of 0.2 or more and a magnetic layer applied on at least one surface of said film.By using the polyester film containing small air bubbles as the base material of the magnetic card, flexibility, flatness and punching property, which were insufficient in a magnetic card using a conventional polyester film, are improved.

Abstract: Disclosed in this invention is a shrinkable polyester film having a shrinkage of not less than 40% after 5-minute treatment in a 100.degree. C. air oven in one of the machine and transverse directions, and a shrinkage of not more than 15% after 5-minute treatment in a 100.degree. C. air oven and a maximum shrinkage stress of not more than 50 g/mm.sup.2 at 40.degree. to 100.degree. C. in the other direction. The shrinkable film of this invention has the excellent shrink characteristics and are substantially free from wrinkling, curling at the end and non-uniformity of shrinkage when the film is shrunk, so that it is suited for use as a label film and has a high industrial value.

Abstract: There is disclosed a sublimation type thermal ink transfer recording material comprising a biaxially drawn film substrate consisting of a polyester base film and an applied primer layer of a reaction product of a polymerizable compound having carbon-carbon unsaturated bonds and a polyester, said substrate being drawn after a solution containing said reaction product is applied on the polyester film; a layer of sublimation type ink formed on said applied layer; and a slippery layer formed on the side opposite to said ink layer. This material has an ink layer which is not easily peeled off and has excellent image-forming ability.

Abstract: A biaxially oriented polyester film simultaneously satisfying the following formulas (I) to (III):.vertline.S.sub.180 -S.sub.120 .vertline..ltoreq.54 (I)T.sub.S.sup.MD .gtoreq.100 (II)Q.sub.120 .ltoreq.0.7 (III)wherein S.sub.180 is shrinking stress (g/mm.sup.2) of the film in the machine direction at 180.degree. C., S.sub.120 is shrinking stress (g/mm.sup.2) of the film in the machine direction at 120.degree. C., T.sub.S.sup.MD is shrinkage initiation temperature (.degree.C.) of the film in the machine direction, and Q.sub.120 is shrinkage (%) of the film in the machine direction after 5 hours' treatment at 120.degree. C., is described. The film has a good dimensional stability due to its low shrinkage, particularly in the machine direction, and substantially free from defect such as wave and wrinkle.It is prepared by biaxially stretching, heat-setting and relaxing an extruded polyester film under particular conditions so as to obtain a biaxially oriented polyester film having these characteristics.