Abstract: The present invention relates to a porous or microporous film of a high molecular weight polyolefin excellent in strength and air-permeability and suitable for use in filtering materials, separators for aqueous electrolyte batteries, separator films for batteries, separator films for electrolytic capacitors, and air-permeable films; for moisture-permeable water-proof use such as paper diapers and house-wrapping films; and for other uses such as cloths, package and printing, as well as a process for producing same. The feature of the present invention resides in an aspect that the film is composed of fibrils comprising extended-chain crystals and lamellar crystals and/or fibrils comprising helicoidal crystals.This porous film of a high molecular weight polyolefin is produced by subjecting an air-impermeable film of a high molecular weight polyolefin to thermal treatment followed by, if necessary, a stretching treatment and/or a thermosetting treatment.

Abstract: A process for producing a porous film of polypropylene comprises subjecting (1) an air-impermeable biaxially stretched film of polypropylene resin comprised predominantly of polypropylene having a crystallinity of at least 40% or (2) an air-impermeable inflation film of polypropylene resin comprised predominantly of polypropylene having a crystallinity of at least 46.5%, in the substantial absence of a plasticizer or a solvent, to a thermal treatment in the presence of a first liquid substantially incapable of dissolving the film while fixing the film in two orthogonal directions for making the film porous.

Abstract: A porous biaxially oriented film comprising a copolymer of an ethylene having an intrinsic viscosity ?.eta.! of from 3.5 to 10.0 dl/g and an .alpha.-olefin having 4 to 8 carbon atoms, the content of the .alpha.-olefin being in a number of from 1.0 to 7.5 per 1000 carbon atoms and the film retaining the structure which is based upon the microfibrils when it is heat-treated at 160.degree. C. under a constrained state and is then observed at room temperature, and a separator made of this film for batteries. The porous biaxially oriented film exhibits excellent gas permeating property over a practicable temperature range, exhibits excellent mechanical strength and, particularly, tensile strength, and loses gas permeating property when a maximum practicable temperature is exceeded. The film can be favorably used as a separator for batteries.

Abstract: A microporous film of high molecular weight polyolefin useful in the prepration of filter mediums or non-aqueous battery separators and a process for producing the film are disclosed. The microporous film of high molecular weight polyolefin contains leaf vein-like fibrils as a main constituent on each of which fibrils indeterminate-form crystallites of not more than 1 .mu.m in size flocculate and has an intrinsic viscosity, ?.eta.!, of 4 dl/g or more and, preferably, has:(a) a void content of 25% or more;(b) a gas permeability of 1900 sec/100 cc or less;(c) a tensile strength of 0.05 GPa or more; and(d) a gas impermeability-acquiring temperature of 140.degree. C. or lower. The microporous film is produced by subjecting a high molecular weight, biaxially oriented polyolefin film of 60% or more in crystallinity to a heat treatment and, if necessary, to a stretch treatment to thereby melt or dissolve the indeterminate-form portion of the film, then crystallizing it onto the fibrils as crystallites.

Abstract: Biaxially oriented films from high molecular weight polyethylene are characterized by a gas permeable structure formed from random-arranged microfibrils. The films have coefficients of static friction and kinetic friction of not more than 1.0. The biaxially oriented films are further characterized by service smoothness as well as tensile (tangent) modulus and tensile strength. The films may be used for lamination, filter, or for packaging for moisture absorbers. The biaxially oriented films may be obtained by extracting a hydrocarbon plasticizer from a sheet formed from the high molecular weight polyethylene and a hydrocarbon plasticizer, stretching the resulting sheet to obtain an oriented film having a specific surface area of at least 70 m.sup.2 /g and a fibril structure, and heating the oriented film under a standard length constraint to reduce the oriented film in specific area by at least 20 m.sup.2 /g.

Abstract: Biaxially oriented films from high molecular weight polyethylene are characterized by a gas permeable structure formed from random-arranged microfibrils. The films have coefficients of static friction and kinetic friction of not more than 1.0. The biaxially oriented films are further characterized by service smoothness as well as tensile (tangent) modulus and tensile strength. The films may be used for lamination, filter, or for packaging for moisture absorbers. The biaxially oriented films may be obtained by extracting a hydrocarbon plasticizer from a sheet formed from the high molecular weight polyethylene and a hydrocarbon plasticizer, stretching the resulting sheet to obtain an oriented film having a specific surface area of at least 70 m.sup.2 /g and a fibril structure, and heating the oriented film under a standard length constraint to reduce the oriented film in specific area by at least 20 m.sup.2 /g.

Abstract: Biaxially oriented films from high molecular weight polyethylene are characterized by a gas permeable structure formed from random-arranged microfibrils. The films have coefficients of static friction and kinetic friction of not more than 1.0. The biaxially oriented films are further characterized by service smoothness as well as tensile (tangent) modulus and tensile strength. The films may be used for lamination, filter, or for packaging for moisture absorbers. The biaxially oriented films may be obtained by extracting a hydrocarbon plasticizer from a sheet formed from the high molecular weight polyethylene and a hydrocarbon plasticizer, stretching the resulting sheet to obtain an oriented film having a specific surface area of at least 70 m.sup.2 /g and a fibril structure, and heating the oriented film under a standard length constraint to reduce the oriented film in specific area by at least 20 m.sup.2 /g.

Abstract: The biaxially oriented films of high molecular weight polyethylene is formed and its surface modified to provide a hydrophilic property to the resulting film. The film is prepared by melt-kneading the high molecular weight polyethylene with an ordinarily solid hydrocarbon plasticizer and a raw fabric sheet is formed from the resulting molten mixture. After the hydrocarbon plasticizer is extracted the resulting unstretched sheet is stretched under conditions providing a stretched film having a specific surface area of 70 m.sup.2 /g or more and a fibril structure. This stretched film is then heated under standard length constraint conditions to reduce the specific surface area of the stretched film by at least 20 m.sup.2 /g to obtain a biaxially oriented film of high molecular weight polyethylene.

Abstract: If ultra-high-molecular-weight polyethylene having an intrinsic viscosity (.beta.) of at least 5 dl/g is grafted with a silane compound in the presence of a radical initiator and extrusion-molded and the extrudate is impregnated with a silanol condensation catalyst after or during drawing and is then exposed to water to effect crosslinking, there is obtained a novel molecularly oriented molded article in which increase of the melting temperature, which is not observed in conventional drawmolded or crosslinked molded articles of polyethylene, can be attained, and even if this molecularly oriented molded article is exposed to a temperature of 180.degree. C. for 10 minutes, the molded article is not fused but the shape is retained and even after this heat history, a high strength retention ratio can be maintained.

Abstract: Disclosed is a fiber-reinforced polymer molded body which comprises a matrix of a polymer having a processing temperature lower than 220.degree. C. and at least one reinforcing layer of a molecularly oriented and silane-crosslinked ultra-high-molecular-weight polyethylene fiber, which is laminated with or embedded in the matrix, wherein the reinforcing layer substantially retains the orientation crystal structure of the ultra-high-molecular-weight polyethylene fiber.

Abstract: If ultra-high-molecular-weight polyethylene having an intrinsic viscosity (.eta.) of at least 5 dl/g is grafted with a silane compound in the presence of a radical initiator and extrusion-molded and the extrudate is impregnated with a silanol condensation catalyst after or during drawing and is then exposed to water to effect crosslinking, there is obtained a novel molecularly oriented molded articles in which increase of the melting temperature, which is not observed in conventional draw-molded or crosslinked molded articles of polyethylene, can be attained, and even if this molecularly oriented molded article is exposed to a temperature of 180.degree. C. for 10 minutes, the molded article is not fused but the shape is retained and even after this heat history, a high strength retention ratio can be maintained.

Abstract: A graft-modified ultrahigh-molecular-weight polyethylene obtained by grafting (A) an ultrahigh-molecular-weight polyethylene having an inherent viscosity [.eta.], determined at 135.degree. C. in decalin, of at least 5 dl/g with (C) an unsaturated carboxylic acid graft-copolymerizable therewith or its graft-copolymerizable derivative, under melt-kneading condition in the presence of (B) an aliphatic compound having a melting point, determined by the DSC method, of at least 10.degree. C. and a boiling point of at least 130.degree. C., an amount of the component (C) grafted in said graft-modified ultrahigh-molecular-weight polyethylene being 0.01 to 10% by weight, and said graft-modified ultrahigh-molecular-weight polyethylene being substantially free of an insoluble gel product and having a tensile strength of at least 1.0 GPa; and a process for producing the same.

Abstract: Stretched articles of ultrahigh-molecular-weight polyethylene are prepared by melt-kneading a mixture of ultrahigh-molecular-weight polyethylene with a paraffinic wax having a melting point of 40.degree. to 120.degree. C. and a weight average molecular weight of at least 230 but less than 2000 in a screw extruder while maintaining the temperature of the mixture at 180.degree. to 280.degree. C. The molten mixture is melt-extruded through a die at a temperature of 180.degree. to 300.degree. C. under a draft condition of a draft ratio of less than 2 or in the absence of a draft and the resulting unstretched extrudate is cooled to solidify it. The unstretched solidified extrudate is than subjected to a stretching treatment in a heated liquid medium which is a solvent for the paraffinic wax at a temperature of 60.degree. to 140.degree. C. at a particular stretch ratio.

Abstract: Stretched articles of ultrahigh-molecular-weight polyethylene are prepared by melt-kneading a mixture of ultrahigh-molecular-weight polyethylene with a paraffinic wax having a melting point of 40.degree. to 120.degree. C. and a weight average molecular weight of at least 230 but less than 2000 in a screw extruder while maintaining the temperature of the mixture at 180.degree. to 280.degree. C. The molten mixture is melt-extruded through a die at a temperature of 180.degree. to 300.degree. C. and the resulting unstretched extrudate is cooled to solidify it. The unstretched solidified extrudate is then subjected to a stretching treatment at a temperature of 60.degree. to 140.degree. C. at a particular stretch ratio. Stretch shaped articles of ultrahigh-molecular-weight polyethylene having high tensile strength and modulus of elasticity are produced uniformly and reproducibly. The stretched shaped articles are substantially free from stretching uneveness.