Abstract: The present invention provides a microporous polyolefin membrane of high permeability and novel structure, and also provides a method of producing the same, wherein its average pore size is gradually decreases from at least one membrane surface towards its center. The method of producing the microporous polyolefin membrane comprises the steps of extruding the solution, composed of 10 to 50 weight % of (A) a polyolefin having a weight-average molecular weight of 5×105 or more or (B) a composition containing this polyolefin and 50 to 90 weight % of a solvent, into a gel-like formed article and removing the solvent therefrom, wherein a treatment step with a hot solvent is incorporated.

Abstract: It is an object of the present invention to provide a microporous polyolefin membrane, high in pin puncture strength, adequate in pore diameter and high in porosity, comprising (A) an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 5×105 or more, or (B) a composition containing an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 5×105 or more, and having a porosity of 30 to 95%, bubble point exceeding 980 KPa and pin puncture strength of 4,900 mN/25 &mgr;m or more. The membrane can be used as a filter or as a separator for a battery.

Abstract: It is an object of the present invention to provide a microporous polyolefin membrane, high in elongation and porosity, low in shrinkage, and capable of improving battery characteristics, safety and productivity, when used for battery separators. The microporous polyolefin membrane of the present invention comprises (A) an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 5×105 or more, or (B) a composition containing an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 5×105 or more, and having a porosity of 45 to 95%, elongation at break of 300% or more, bubble point exceeding 980 KPa and thermal shrinkage in the TD direction of 3% or less. The present invention also provides a method for producing the above microporous polyolefin membrane.

Abstract: The thin film of non-protonic electrolyte comprises the microporous polyolefin film impregnated with an immobilized non-protonic electrolytic solution, where the film is treated to have improved affinity for the non-protonic solution by graft polymerization of the film with a monomer which can dissolve the non-protonic electrolytic solution, coating of the film with terminal-modified polypropylene which can dissolve the non-protonic electrolytic solution or coating of the film with wax which can dissolve the non-protonic electrolytic solution. The electrolyte-immobilized liquid-film conductor comprises the microporous polyolefin film impregnated with an immobilized non-protonic electrolytic solution, where the film contains an electron-conductive substance and is treated to have improved affinity for the non-protonic solution. The thin film of non-protonic electrolyte comprising the microporous polyolefin film gives a polymer battery, such as lithium battery, when combined with an anode and cathode.

Abstract: The present invention provides a thin film of non-protonic electrolyte and electrolyte-immobilized liquid-film conductor, easily produced into a thin film and to have a large area, securely holding the non-protonic electrolytic solution over a wide temperature range, and showing stability for extended periods and improved mechanical strength. They comprise a polyolefin film with a solvent-resistant polyolefin as the basic component, which is impregnated with the non-protonic electrolytic solution to immobilize it. The polyolefin composition for the film contains a terminal-modified polypropylene having, in the terminal chain, a functional group showing an affinity for the solvent for the electrolytic solution for the thin film of non-protonic electrolyte, and further contains an electron-conductive substance in addition to the terminal-modified polypropylene for the electrolyte-immobilized liquid-film conductor. As a result, the polyolefin film stably holds the solvent for the electrolytic solution.

Abstract: A method for producing a highly permeable microporous polyolefin membrane including the steps of preparing a polyolefin solution containing 5-40 weight % of a polyolefin or a polyolefin composition and 95-60 weight % of a solvent, the polyolefin having a weight-average molecular weight of not less than 3.times.10.sup.5 and less than 1.times.10.sup.6 and a weight-average molecular weight/number-average molecular weight of 5-300, and the polyolefin composition having a weight-average molecular weight of not less than 3.times.10.sup.5 and less than 1.times.10.sup.6 and a weight-average molecular weight/number-average molecular weight of 5-300 as a whole, extruding the polyolefin solution, stretching the extrudate uniaxially at a draft ratio of 3-50 in a molten state, cooling the stretched extrudate to solidify to a gel-like sheet, removing residual solvent, drying the resultant sheet, and heat-setting at a temperature of 80.degree. C. or higher and its melting point or lower.

Abstract: A microporous polyolefin composite membrane, preferably for use as a battery separator, comprising a microporous polyolefin membrane and a polyolefin nonwoven fabric laminated on at least one surface of the microporous polyolefin membrane. The composite membrane has a thickness of 25 to 200 .mu.m, a porosity of 30 to 70%, an air permeability of 100 to 2000 sec/100 cc and a surface opening area ratio of 50 to 90% on at least one outer surface thereof. The microporous polyolefin membrane comprises a matrix polyolefin component which is a polyolefin having a weight average molecular weight of 5.times.10.sup.5 or more or a polyolefin mixture containing the polyolefin having a weight average molecular weight of 5.times.10.sup.5 or more, and has a porosity of 30 to 95%, an air permeability of 100 to 2000 sec/100 cc, an average open pore diameter of 0.001 to 1 .mu.m and a tensile strength at break of 500 kg/cm.sup.2 or more.

Abstract: A method of producing a microporous thermoplastic resin membrane of excellent permeability having uniform and fine micropores without filling stress concentrators to the thermoplastic resin is provided. Namely, there is provided a method of producing a microporous thermoplastic resin membrane, in which a thermoplastic resin foam incorporating fine cells having a ratio B/A between a cell size (A) and a wall thickness (B) of the cells of less than 0.5 and having a void ratio of not less than about 50% is subjected to plastic deformation of the boundaries of the cells themselves sufficient to cause shape deformation of the cells, thereby breaking the boundaries of the cells. Also there is provided a microporous thermoplastic resin membrane of excellent permeability having uniform and fine micropores produced by the method as described above.

Abstract: An efficient method of producing a microporous polyolefin membrane having improved tensile strength and pierce strength is provided, in which a solution having dissolved therein 5% by weight to 50% by weight of a polyolefin whose weight-average molecular weight is in the range of 5.times.10.sup.5 to 2.5.times.10.sup.6 and whose weight-average molecular weight to number-average molecular weight ratio is less than 10, is extruded and rapidly cooled to obtain a gel-like product which is then stretched and has remaining solvent removed therefrom.

Abstract: A method of producing a microporous polyolefin membrane having a relatively large pore size and a high permeability, the membrane being suitable for use in water treatment, microfiltration, etc. The method comprises dissolving a polyolefin composition in a solvent to prepare a solution, extruding the solution through a die lip into a form of gel-like sheet, rapidly cooling the gel-like sheet, removing a residual solvent in the cooled sheet by a washing solvent, and drying the resultant sheet to remove the washing solvent. The polyolefin composition is a mixture of (A) an ultra high molecular weight polyolefin having a weight average molecular weight of 5.times.10.sup.5 or more and (B) a polyolefin having a weight average molecular weight less than 5.times.10.sup.5, and a weight ratio of (B)/(A) is 0.2 to 20.

Abstract: A method of manufacturing a polyolefin solution continuously and in a stable manner with a high yield which comprises heading a polyolefin resin with a liquid composed of a solvent for the polyolefin resin, and is characterized in that; (1) a continuous kneader having a self-cleaning action is used, and (2) a starving state is maintained in the internal sections of the header at a polyolefin resin feed section, a liquid feed section, and the section in which the kneading of the polyolefin resin and the liquid is initially carried out.

Abstract: A microporous polyolefin membrane made of a polyolefin composition containing 1 weight % or more of an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 7.times.10.sup.5 or more and having a weight-average molecular weight/number-average molecular weight ratio of 10-300, the microporous membrane having a thickness of 0.1-25 .mu.m, a porosity of 35-95%, an average pore diameter of 0.001-0.2 .mu.m and a breaking strength of 0.2 kg or more per 15 mm width is produced by (a) preparing a solution comprising 10-50 weight % of the polyolefin composition and 50-90 weight % of a solvent; (b) extruding the solution through a die; (c) cooling the extruded solution to form a gel-like article; (d) stretching the gel-like article at a temperature equal to or lower than a melting point of the polyolefin composition +10.degree. C; and (e) removing the remaining solvent.

Abstract: A process for producing a relatively thick microporous ultra-high-molecular-weight polyolefin membrane, including the steps of: (1) preparing a solution of an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 5.times.10.sup.5 or more; (b) extruding the solution from a die while rapidly cooling it in advance to its gelation temperature or below, thereby forming a gel-like sheet; (c) removing at least 10 wt % of the solvent from the gel-like sheet so that the gel-like sheet contains 10 to 90 wt % of the ultra-high-molecular-weight polyolefin; (d) stretching the gel-like sheet at a temperature equal to or lower than that which is 10.degree. C. above the melting point of the ultra-high-molecular-weight polyolefin; and (e) removing the residual solvent from the stretched product.

Abstract: Disclosed are immobilized electrolyte membranes having a high electric conductivity and a high mechanical strength, where an ionic conductor such as a polymer electrolyte or an ion-exchange resin is immobilized in pores of a porous solid polymer membrane, particularly of polyolefin having a weight average molecular weight of not less than 5.times.10.sup.5, the porous solid polymer membrane having a thickness of 0.1 .mu.m to 50 .mu.m, a porosity of 40% to 90%, a tensile strength of not less than 200 kg/cm.sup.2, and an average permeable pore diameter of 0.001 .mu.m to 0.1 .mu.m.

Abstract: A micro-porous membrane of ultra-high-molecular-weight alpha-olefin polymer having a weight-average molecular weight greater than 5.times.10.sup.5, the micro-porous membrane having through holes 0.01 to 1 micrometer in average pore size, with a void ratio from 30 to 90% and being oriented such that the linear draw ratio in one axis is greater than two and the areal draw ratio is greater than ten. The micro-porous membrane is obtained by forming a gel-like object from a solution of an alpha-olefin polymer having a weight-average molecular weight greater than 5.times.10.sup.5, removing at least 10 wt % of the solvent contained in the gel-like object so that the gel-like object contains 10 to 90 wt % of alpa-olefin polymer, orientating the gel-like object at a temperature lower than that which is 10.degree. C. above the melting point of the alpa-olefin polymer, and removing the residual solvent from the orientated product.

Abstract: A polyethylene microporous membrane having a thickness of at most 10 .mu.m, a breaking strength of at least 200 kg/cm.sup.2 and a porosity of at least 30% is produced by heating and dissolving polyethylene having a weight average molecular weight of at least 5.times.10.sup.5 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet and then removing the residual solvent therefrom.

Abstract: A polyethylene superthin film having a thickness of at most 3 .mu.m, a tensile modulus of at least 2000 kg/cm.sup.2, a breaking strength of at least 500 kg/cm.sup.2 and a haze of at most 10% is produced by heating and dissolving polyethylene having a weight average molecular weight of at least 5.times.10.sup.5 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet, removing the residual solvent therefrom and then subjecting the stretched product to a compressing treatment at a temperature of at most the melting point of the polyethylene.

Abstract: A polyethylene microporous membrane having a thickness of at most 10 .mu.m, a breaking strength of at least 200 kg/cm.sup.2 and a porosity of at least 30% is produced by heating and dissolving polyethylene having a weight average molecular weight of at least 5.times.10.sup.5 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet and then removing the residual solvent therefrom.