A matte film for hot pressing and a manufacturing method thereof are provided. The manufacturing method includes steps of forming at least one polyester composition into an unstretched polyester thick film and stretching the unstretched polyester thick film in a machine direction (MD) and a transverse direction (TD). The polyester composition includes 81% to 97.9497% by weight of a polyester resin, 0.02% to 2% by weight of an antioxidative ingredient, 0.0003% to 1% by weight of a nucleating agent, 0.01% to 2% by weight of a flow aid, 0.01% to 2% by weight of a polyol ester based polyester modifier, 0.01% to 2% by weight of an inorganic polyester modifier, and 2% to 10% by weight of silica particles. The polyester resin has an intrinsic viscosity between 0.60 dl/g and 0.80 dl/g.

A polyolefin porous separator includes a first surface and a second surface corresponding to the first surface. The surfaces of the polyolefin porous separator contain dendritic crystals and micropores, the dendritic crystals intersect with the micropores on the first surface or/and the second surface, and the dendritic crystals penetrate through the second surface from the first surface. A preparation method of the polyolefin porous separator includes: (1) a mixed melting of polyethylene resin and a mineral oil; (2) an extrusion of the mineral oil/polyethylene resin molten mixture; (3) a stretching of a thick sheet in a machine direction (MD); (4) a stretching of the separator in a transverse direction (TD); (5) immersing the separator into a solvent to extract the mineral oil; (6) a secondary stretching of the separator in the TD; and (7) subjecting the separator having the longitudinal crystals to a heat-setting treatment and then rolling up.

The present invention relates to a polymer comprising moieties derived from ethylene and moieties derived from 1-hexene, wherein the polymer has: (a) a density of ≥910 and ≤930 kg/m.sup.3 as determined in accordance with ASTM D1505 (2010); (b) a melt mass-flow rate of ≥0.5 and ≤5.0 g/10 min, as determined in accordance with ASTM D1238 (2013) at a temperature of 190° C. under a load of 2.16 kg; (c) a fraction that is not eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature ≥30.0° C. of ≥8.0 wt %, with regard to the total weight of the polymer; and (d) a fraction eluted in a-TREF at a temperature ≥94.0° C. of ≥20.0 wt %, with regard to the total weight of the polymer. Such polymer allows for the production of bi-directionally oriented films having a particularly desirable ability to be stretched at a high stretching ratio, in both the machine direction and in the transverse direction, and particularly to be stretched to a high stretching ratio in the machine direction and the transverse direction combined. Further this polymer allows for production of bi-directionally oriented films within a particularly and desirably broad temperature range in which the stretching can be performed without imparting any deficiencies of hampering the film production processes in continuous film production.

There is provided a release film comprising a substrate film and a resin layer provided on at least one surface of a substrate film, wherein the resin layer comprises 100 parts by mass of an acid-modified polyolefin resin, 1 to 20 parts by mass of a crosslinking agent and 10 to 1,000 parts by mass of a polyvinyl alcohol having a saponification rate of 99% or lower.

A polyester film comprises a polyester (A) composed mainly of polybutylene terephthalate and a polyester (B) composed mainly of polyethylene terephthalate, wherein a mass ratio (A/B) between the polyesters (A) and (B) is 70/30 to 55/45, a dry heat shrinkage rate (A) through heat treatment at 160° C. for 30 minutes is 20% or less in any of four directions on a film surface (0°, 45°, 90° and 135®), a difference between a maximum value and a minimum value of these dry heat shrinkage rates is 5% or less, a dry heat shrinkage rate (B) through heat treatment at 200° C. for 15 minutes is 35% or less in any of the four directions, a difference between a maximum value and a minimum value of these dry heat shrinkage rates is 5% or less, and a thickness variation in the four directions is 10% or less.

A polymer thin film is characterized by a first in-plane refractive index (n.sub.x) along a first direction of the polymer thin film, a second in-plane refractive index (n.sub.y) along a second direction of the polymer thin film orthogonal to the first direction, and a third refractive index (n.sub.z) along a thickness direction substantially orthogonal to both the first direction and the second direction, where n.sub.x>n.sub.z>n.sub.y. Such a polymer thin film may exhibit one or more of (a) an in-plane birefringence of at least approximately 0.05, and (b) n.sub.x greater than approximately 1.7.

A microporous membrane is made by a dry-stretch process and has substantially round shaped pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 5.0. The method of making the foregoing microporous membrane includes the steps of: extruding a polymer into a nonporous precursor, and biaxially stretching the nonporous precursor, the biaxial stretching including a machine direction stretching and a transverse direction stretching, the transverse direction stretching including a simultaneous controlled machine direction relax.

A battery separator includes a polyolefin microporous membrane and a porous layer placed on at least one surface of the polyolefin microporous membrane. The polyolefin microporous membrane has a variation range of an F25 value in a longitudinal direction of 1 MPa or less. The F25 value indicates a value obtained by dividing a load value measured at 25% elongation of a specimen with use of a tensile tester by a cross-sectional area of the specimen. The porous layer contains a fluorine-based resin and an inorganic particle and has an average thickness T(ave) of 1 to 5 μm.

A void-containing polyester is disclosed which is excellent in concealing properties, whiteness, and thermal dimensional stability. A void-containing polyester film includes an internal void-containing layer (layer A). The void-containing layer contains a polyester matrix resin and a polypropylene dispersed resin, and satisfies the following requirements (1) to (3), and an apparent density of the film is in a range of 0.8 to 1.2 g/cm.sup.3. (1) A melt viscosity (η1) of the polyester resin at a melting temperature of 280° C. and a shear rate of 121.6 sec.sup.−1 is 90 to 400 Pa.Math.s (2) A melt viscosity (η2) of the polypropylene resin at a melting temperature of 280° C. and a shear rate of 121.6 sec.sup.−1 is 300 to 850 Pa.Math.s (3) A melt viscosity ratio (η2/η1) of the polyester resin and the polypropylene resin at a melting temperature of 280° C. and a shear rate of 121.6 sec.sup.−1 is 1.5 to 4.5.

The optical film according to the present invention has a feature that it has high adhesiveness and excellent property of blocking UV light even while using an acrylic resin having no ring structure in the main chain.