Disclosed are a polyolefin resin composition usable in manufacturing a single-layered dry porous membrane having excellent meltdown and shutdown properties, and a porous membrane using the polyolefin resin composition. The present invention provides a polyolefin resin composition for a porous membrane, wherein the polyolefin resin composition includes 30 wt % to 70 wt % of a high-density polyethylene having a melt flow index (190 C., 2.16 kg load) of 0.1 g/10 min to 5 g/10 min, a crystallization temperature of 115 C. to 125 C., and a degree of crystallinity of 75% or greater, and 30 wt % to 70 wt % of a high-crystallinity polypropylene having a melt flow index (230 C., 2.16 kg load) of 5 g/10 min to 20 g/10 min.

Microporous sheet product and methods of making and using the same. In one embodiment, the microporous sheet product is made by a process that includes melt-extruding a sheet material using an extrusion mixture that includes (i) a cyclic olefin copolymer, (ii) an electrolyte swellable thermoplastic, and (iii) a compatibilizing agent that promotes mixing of the cyclic olefin copolymer and the electrolyte swellable thermoplastic, the compatibilizing agent having a boiling point in the range of 135-300 C. As an example, the cyclic olefin copolymer may be an ethylene-norbornene copolymer, the electrolyte swellable thermoplastic may be polyethylene oxide, and the compatibilizing agent may be mineral spirits. After extrusion, the sheet material may be cooled, and the compatibilizing agent may be removed, forming an ionically-conductive microporous sheet product. The microporous sheet product has high-temperature stability and gels when exposed to a liquid electrolyte, enabling high ionic conductivity when used as a battery separator.

A method for joining braids that are used for a braid-reinforced hollow fiber membrane, produced by the method inserting a core material into the hollow parts of ends of two braids to be joined to connect the two braids, covering the joint part with a heat-shrinkable tube, and shrinking the heat-shrinkable tube by heating at 120 to 160 C., thereby joining the braid ends together, and that can exhibit sufficient joint strength when load is applied during spinning, or when a porous hollow fiber membrane is used as a treatment membrane for water purification treatment, sewage and waste water treatment, etc. A braid-reinforced porous hollow fiber membrane is produced by allowing braids whose ends are joined by the above method to pass through the inner nozzle of a double annular spinning nozzle, applying a membrane-forming dope discharged from the outer nozzle of the double annular spinning nozzle to the outer surfaces of the joined braids passing through the inner nozzle of the double annular spinning nozzle for impregnation, then coagulating the braids in a coagulating liquid, and winding the braids on a bobbin.

A Polyvinylidene fluoride-based microporous membrane comprising: a substrate film; and the following microporous membrane, wherein the microporous membrane is an asymmetric membrane, and has a skin layer in which micropores are formed and a support layer which supports the skin layer and in which pores larger than the micropores are formed, a material of the microporous membrane is a polyvinylidene fluoride-based resin, the skin layer has a plurality of spherical bodies, a plurality of linear binding materials extend three-dimensionally from the respective spherical bodies, the adjacent spherical bodies are connected with each other by the linear binding materials to form a three-dimensional network structure where the spherical bodies serve as intersections, and the number of defects (the number of colored coarse voids) is less than 20.

The invention relates to a method for producing thin, porous membranes from crosslinkable silicone compositions (S), in which: in a first step, a mixture of the silicone compositions (S) with a pore forming agent (P) and, where appropriate, solvent (L) is formed; in a second step, the mixture is placed in a mould and the silicone composition (S) is vulcanised and any solvent (L) present is removed, producing a crosslinked membrane with pores, in a third step, the pore forming agent (P) in removed from the crosslinked membrane; and in a fourth step, the pores of the membrane are opened by stretching. The invention also relates to the membranes produced in this manner and to the use thereof for separating mixtures, in wound plasters, as packaging materials and as textile membranes.

A method for producing a microporous material comprising the steps of: providing an ultrahigh molecular weight polyethylene (UHMWPE); providing a filler; providing a processing plasticizer; adding the filler to the UHMWPE in a mixture being in the range of from about 1:9 to about 15:1 filler to UHMWPE by weight; adding the processing plasticizer to the mixture; extruding the mixture to form a sheet from the mixture; calendering the sheet; extracting the processing plasticizer from the sheet to produce a matrix comprising UHMWPE and the filler distributed throughout the matrix; stretching the microporous material in at least one direction to a stretch ratio of at least about 1.5 to produce a stretched microporous matrix; and subsequently calendering the stretched microporous matrix to produce a microporous material which exhibits improved physical and dimensional stability properties over the stretched microporous matrix.

Halogen-free, microporous polyolefin membranes are disclosed herein. The halogen-free, microporous polyolefin membranes can be manufactured using an environmentally friendly manufacturing process that includes extrusion of polymer-plasticizer mixtures followed by sheet formation and extraction of the plasticizer with a halogen-free solvent. The halogen-free solvent has a flashpoint greater than about 23 C. and an initial boiling point at least about 50 C. lower than the flashpoint of the plasticizer. The process can further be a closed loop process in which the halogen-free solvent can be reused.

A crosslinked polyolefin separator having an average value of light transmittance of 30% or more in a region of 380 nm to 700 nm, after four sides of the separator are fixed and allowed to stand at 130 C. for 30 minutes. A method for manufacturing the crosslinked polyolefin separator is also provided. The crosslinked polyolefin separator has a low shutdown temperature to provide improved safety. The crosslinked polyolefin separator also has a high meltdown temperature and is inhibited from die-drooling.

A hollow fiber membrane and a method of preparing the same. The hollow fiber membrane has an inner surface and an outer surface, wherein the inner surface has a zebra-stripe pattern in which a dense portion and a porous portion are alternately formed in a longitudinal direction of the hollow fiber membrane.

A crosslinked polyolefin separator having an average value of light transmittance of 30% or more in a region of 380 nm to 700 nm, after four sides of the separator are fixed and allowed to stand at 130? C. for 30 minutes. A method for manufacturing the crosslinked polyolefin separator is also provided. The crosslinked polyolefin separator has a low shutdown temperature to provide improved safety. The crosslinked polyolefin separator also has a high meltdown temperature and is inhibited from die-drooling.