Provided are a polymer film including a particle A having a constricted structure and a polymer B; a laminate including the polymer film and a metal layer or metal wire disposed on at least one surface of the polymer film; and a method of producing the polymer film.

A composite porous membrane contains at least one porous base layer and at least one uniaxially stretched coating layer located on at least one side surface of the porous base layer. For example, the composite porous membrane comprises at least one porous base layer and at least one nanofiber-like non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite porous membrane and located on one or two side surfaces of the porous base layer, or the composite porous membrane comprises a biaxially stretched polypropylene porous base layer and a uniaxially stretched coating layer located on at least one side surface of the porous base layer. The composite porous membrane is coated with a coating solution prior to transversely stretching. The nanofiber-like non-polyolefin polymer porous layer may reduce cracking of the composite porous membrane in the machine direction.

Provided are methods of producing materials suitable for use as a component of an electrochemical cell such as electrode active layers or solid state electrolyte and/or separator materials. Processes include combining an active with a fibrillizable binder and intermixing in a screw fibrillator to produce a fibrillized material with greatly increased physical and optionally electrochemically characteristics relative to those materials produced by other processes such as simple slurry casting or intermixing in a jet mill.

Provided is a filtration method that includes a cleaning step and involves the use of a porous membrane, wherein the filtration method offers exceptional resistance to cleaning solutions (chemicals) (chemical liquid resistance) and exceptional filtration performance, and has a long service life. A filtration method includes the following steps: a filtration step in which a liquid to be processed that contains a material to be filtered is passed through a porous membrane configured from a resin having a three-dimensional mesh structure, and a filtrate is separated from the material to be filtered; and a cleaning step in which the porous membrane has a cleaning solution passed therethrough or is immersed in the cleaning solution so that the interior of the porous membrane is cleaned.

A plate-like composite material in which peeling of a conductor layer and the like serving as wiring is less liable to occur is provided. The plate-like composite material includes: a pore-containing layer, which contains a fluororesin and a filler, and which contains pores; and a resin layer containing a fluororesin bonded to one surface, or each of both surfaces, of the pore-containing layer, wherein the pore-containing layer includes, in a vicinity of an interface with the resin layer, a high resin content region, which contains the fluororesin in a content higher than a content in a remaining region of the pore-containing layer, and which contains the pores in a content lower than a content in the remaining region, and wherein the high resin content region has a thickness starting from the interface of from 0.20 μm to 10 μm.

An ethylene/tetrafluoroethylene copolymer satisfying the following formula (1):

75≤tan δ(60)/tan δ(5)×100≤225  (1)

wherein peak intensities, determined by Fourier transform infrared spectroscopy, of vibrations derived from a —CF.sub.2H group, a —CF.sub.2CH.sub.2COF group, a —COF group, a —COOH group, a dimer of a —CF.sub.2COOH group and a monomer of a CF.sub.2CH.sub.2COOH group, a —COOCH.sub.3 group, a —CONH.sub.2 group, and a —CH.sub.2OH group satisfy the following formula (2):

PI.sub.A/(PI.sub.B+PI.sub.C+PI.sub.D+PI.sub.E+PI.sub.F+PI.sub.G+PI.sub.H)≥0.60  (2)

wherein the loss tangents (tanδ) and peak intensities (PI) are as defined herein.

A film includes a copolymer having a tetrafluoroethylene-based unit and an ethylene-based unit, in which the film has a haze of from 1.2% to 8.0%, an ultraviolet reflectance of less than 17.0%, and a thickness of from 250 to 400 μm.

Provided is a porous polytetrafluoroethylene membrane in which an absolute value of a difference in lightness between one principal surface and the other principal surface is 1.0 or more, where the lightness is lightness L* of CIE 1976 (L*, a*, b*) color space specified in JIS Z8781-4: 2013. The porous polytetrafluoroethylene membrane may be colored black or gray. The porous polytetrafluoroethylene membrane provided can have properties with a reduced coloring-induced deterioration.

A heat-resistant release sheet is configured to be disposed, when a resin or a target including a resin is used in a step involving heating and melting of the resin, between the resin or the target and a member to be brought into contact with the resin or the target to prevent direct contact between the resin or the target and the member. The sheet includes a skived sheet including polytetrafluoroethylene (PTFE) or a modified PTFE. A content of a tetrafluoroethylene (TFE) unit in the modified PTFE is 99 mass % or more. In each of two directions being in-plane directions of the heat-resistant release sheet and being perpendicular to each other, a rate of dimensional shrinkage induced by heating at 175° C. for 30 minutes is more than 0%. The sheet includes the skived sheet including the heat-resistant resin but prevents occurrence of problems attributable to inclusion of the skived sheet.

Provided is a multilayer film that includes a top layer and a barrier layer. The top layer includes a polyurethane network and having an exposed major surface. The barrier layer includes a fluoropolymer and having opposed first and second major surfaces, where the first major surface is modified by a surface treatment and wherein the top layer is disposed on the first major surface. When bonding to a curable substrate, the barrier layer can prevent migration of low molecular weight species from the curable substrate into the polyurethane network, thereby avoiding discoloration resulting from exposure of these species to ultraviolet light and other weathering factors.