Abstract: This film provides a polyethylene terephthalate film whereby dimensional variation in various steps can be reduced, particularly when the film is used as a substrate film for a flexible device, and that is suitable as a substrate film having minimal curl and excellent appropriateness for processing. This biaxially oriented polyethylene terephthalate film has a degree of crystallinity (Xc) of 0.35 to 0.50, the intrinsic viscosity (IV) of the resin constituting the film is 0.66-1.0 dl/g, the coefficient of thermal expansion at a temperature of 50-170° C. in each of the machine direction and transverse direction of the film is 0.29 ppm/° C., and the degree of thermal shrinkage at 180° C. in each of the machine direction and transverse direction of the film is 0.5%-1.0%.

Abstract: Disclosed are a biaxially oriented polyester film which is excellent in dimensional stability, especially dimensional stability against environmental changes in, for example, temperature and humidity, and a polyester capable of providing the biaxially oriented polyester film with excellent dimensional stability. There is provided a copolymerized aromatic polyester containing aromatic dicarboxylic acid components represented by the following formulae (I) and (II) and a glycol component represented by the following formula (III), wherein a 4,4?-(alkylenedioxy)bisbenzoic acid component represented by the formula (I) is contained in an amount of 5% by mole or more and less than 90% by mole on the basis of a molar number of an aromatic dicarboxylic acid component; and a film thereof.

Abstract: A biaxially oriented laminated polyester film which has excellent dimensional stability to environmental changes such as temperature and humidity variations and excellent flatness and windability. A biaxially oriented laminated polyester film comprising a film layer B on one side of a film layer A and having a surface roughness (RaB) on the film layer B side which is 1.0 nm or more larger than the surface roughness (RaA) on the film layer A side, wherein at least one of the film layers comprises an aromatic polyester (I) composed of a glycol component and a dicarboxylic acid component containing 5 mol % or more and less than 80 mol % of a recurring unit represented by the following formula (A): wherein RA is an alkylene group having 1 to 10 carbon atoms.

Abstract: A thin biaxially oriented film excellent in dimensional stability against humidity change, as well as a magnetic recording medium and a film capacitor using the same. The present invention provides a laminated biaxially oriented film comprising: at least one layer comprising an aromatic polyester (a); and at least one layer of a polyolefin (b) having a melting point of from 230 to 280° C.; wherein the ratio of the polyolefin (b) is from 2 to 60% based on the entire weight of the film, and the film thickness is from 1 to 10 ?m.

Abstract: An aspect of the present invention relates to a magnetic recording medium comprising a coating layer on a nonmagnetic support, wherein the coating layer comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order, the nonmagnetic support comprises a main component in the form of a resin obtained by mixing and/or copolymerizing a polyester and a polymer having compatibility with the polyester, has a glass transition temperature of equal to or higher than 80° C. but less than 125° C., and has a heat absorption peak, based on enthalpy relaxation, ranging from 0.5 to 2.0 J/g. Another aspect of the present invention relates to a method of manufacturing a magnetic recording medium.

Abstract: An object of the invention is to provide such an oriented polyester film that has a constant thickness, and is excellent in dimensional stability at a high temperature and dimensional stability to temperature change in a working temperature range. The invention relates to an oriented polyester film containing as a major component of a substrate layer polyethylene -2,6-naphthalene dicarboxylate, being stretched at least in one direction, and having a film thickness of from 12 to 250 ?m, wherein (1) a coefficient of linear thermal expansion ?t at a temperature of from 30 to 100° C. is from 0 to 15 ppm/° C. in both longitudinal and width directions of the film, and (2) a thermal shrinkage rate at 100° C. for 10 minutes is 0.5% or less in both longitudinal and width directions of the film.

Abstract: A polyester film for recording medium, having one major surface thereof provided with a coating layer containing fine particles of 5 to 60 nm diameter and an organic compound, wherein the number of fine surface projections existing on the surface of the coating layer is in the range of 3 million to 100 million/mm2, and the number of surface defects of 120 nm or greater height attributed to foreign matter contained in the film is 30/100 cm2 or less, and wherein the polyester contains a titanium compound substantially not having any particle diameter. Thus, there are provided a magnetic recording tape for digital data recording that can reduce dropouts and excels in durability, and further provided a polyester film that is suitable as a base film thereof.

Abstract: A biaxially oriented polyester film wherein the microscopic Raman crystallization index Ic measured in the film thickness direction is in a range of 8 cm?1 to 15 cm?1 and the difference between the maximum value and the minimum value of Ic is 1 cm?1 or less. Another biaxially oriented polyester film wherein the relative power (I10TD) of spatial frequency (1/mm) measured along the transverse direction of at least one surface of the polyester film having been heat treated at 100° C. for 24 hours is in a range of ?25 to 0 dB. These biaxially oriented polyester films are films good in microplanarity even after high-temperature storage or heat loading during processing. These biaxially oriented polyester films are useful as polyester films for use in a magnetic recording material, an electronic material, a stencil film, a sublimatic ribbon and a package material.

Abstract: A magnetic recording tape comprising a nonmagnetic support and a magnetic layer containing ferromagnetic powder and a binder, wherein the nonmagnetic support has an intrinsic viscosity of from 0.40 to 0.60 dl/g and a number average molecular weight of from 12,000 to 24,000, and a distance between an apex of a maximum convexity and a valley of a maximum concavity of the nonmagnetic support on a cross section of an edge of the tape made by cutting the tape in a transverse direction is 2 ?m or less in the transverse direction.

Abstract: A magnetic recording medium including a nonmagnetic substrate and a magnetic layer, wherein the nonmagnetic substrate is made from a polyethylene naphthalate and has a thickness of 6.5 ?m or smaller, and the magnetic recording medium has a creep deformation of 0.30% or less in a longitudinal direction of the magnetic recording medium under a tensile stress of 15.7 MPa applied in the longitudinal direction at 60° C. for 50 hours.

Abstract: The present invention provides a magnetic recording medium having a magnetic layer formed on at least one surface of a nonmagnetic support, wherein the magnetic layer includes a ferrite ferromagnetic hexagonal powder having an average plate diameter of 5 to 50 nm or a fine ferromagnetic metal powder having an average major axis length of 20 to 100 nm together with a binder, and the nonmagnetic support is a composition of a polyester or copolyester having one or more of polytrimethylene 2,6-naphthalate, polytetramethylene 2,6-naphthalate, polypentamethylene 2,6-naphthalate and polyhexamethylene 2,6-naphthalate, in order to provides an excellent running stability, low error rates under various environment and an excellent electromagnetic transforming properties and reliability.