Method of producing microporous polyethylene membrane and storage battery separator

FIELD: process engineering.

SUBSTANCE: invention relates to production of microporous polyethylene membranes to be used in storage battery separators. Membrane is produced by mixing polyethylene resin melt and membrane-forming solvent to prepare solutions of polyethylene resin A with concentration of 25-50% by wt and with that B of 10-30% by wt. Note here that concentration of A exceeds that of B. Melts are simultaneously extruded through spinneret, extrudate is cooled to produce gel-like sheet wherein resins A and B are laminated and membrane-forming solvent is removed. Solutions of resins A and B may be extruded through separate spinnerets with removal of membrane-forming solvent from obtained gel-like sheets A and B, formation of microporous polyethylene membranes A and B and their lamination in controlling mean diametre of pores over membrane depth.

EFFECT: microporous polyethylene membranes with balances mechanical properties, permeability, anti-shrinking properties, resistance to compression, absorption capacity, and pore mean diametre varying over membrane depth.

5 cl, 2 tbl, 16 ex

 

The technical field to which the invention relates.

The present invention relates to a method for producing a microporous polyethylene membrane and the separator of the battery, in particular to a method for producing a microporous polyethylene membrane with an average pore diameter of varying thickness, and battery separator.

Prior art

Microporous polyolefin membranes are widely used in separators for lithium batteries, etc., separators, electrolytic capacitors, various filters, etc., When the microporous polyolefin membranes are used as battery separators, their characteristics significantly affect the operation, performance and safety of batteries. Especially the separators in lithium-ion batteries must possess not only excellent mechanical properties and permeability, but also by the properties of the shutdown and the closure function then to stop the reaction of the battery in case of emergency heat, thus preventing the release of heat, ignition and explosion of the battery, which can be caused by a short circuit external circuit, recharge, etc.; resistance to heat shrinkage, the function of preserving the shape of the separator to avoid direct reaction between the material of the cathode material and the anode even when the temperature etc.

Recently, the important characteristics of the separator not only the permeability and mechanical strength, resistance to heat shrinkage and thermal properties (properties disable and fusion), but also the characteristics of the service life of the battery characteristics such as cycle properties related to battery capacity with frequent use), and the performance of the battery, such as sorption capacity with respect to the electrolyte solution. Electrode of a lithium-ion battery extends through the penetration of lithium during charging and is compressed due to the removal of lithium during discharge, the degree of expansion when charging tends to increase due to the latest increase capacity batteries. Because the separator is compressed by the expansion of the electrode, the separator should be only a small change in permeability during compression to ensure excellent performance cycle. For this purpose there is (i) the technology of production of the separator with a gradient structure, including a layer of coarse-grained structure with a relatively large average pore size, which is undergoing a large deformation with a small change in air permeability when compacted, and a layer of dense patterns with a relatively small average pore size, which is undergoing a big change air PR is Nichelatti at small deformation under compression, a layer of coarse-grained patterns, compensating the expansion of the electrode and permeable, and (ii) technology providing a small deformation of the separator as a whole to prevent rupture of the structure of the pores. These technologies are chosen appropriately depending on the properties of the electrodes.

To improve the sorption capacity with respect to the electrolyte solution is effective and provides a large pore size on the surface of the separator. Also, to prevent the formation of side products during repeated cycles of charge/discharge due to clogging of the separator, it is necessary that the separator was a large pore size on the surface. However, to ensure the mechanical strength required of the dense layer. Thus, to satisfy both requirements of high sorption capacity with respect to an electrolytic solution and a high mechanical strength, it is desirable that the separator had a layer of coarse-grained structure, with a relatively large average pore diameter of at least on one surface, in addition to a layer of dense structure.

It is desirable that the filters for liquids had higher filtration characteristics, and for this purpose the microporous membrane should have smaller pores. However, to avoid compromising the efficiency of the filter, m is croporate membrane must not impair the permeability to fluid. To meet both requirements of high filtration characteristics and high permeability to fluid filters fluid should preferably have the above structure with a gradient. In particular, the balance of the filtration characteristics and permeability for liquids can be controlled by the formation of a microporous membrane with a layer of dense structure as a layer of the substrate and a layer of coarse-grained structure as the filter layer, and the regulation of the layer thickness of the dense-structure layer to the coarse-grained structure.

JP 2000-A discloses a microporous polyolefin membrane with various internal and surface structure, to impart excellent durability at piercing and porosity with an average pore size of 0.01-0.2 μm, at least one surface with an average pore size of 0.5-2 μm. This microporous polyolefin membrane obtained (i) by melt mixing the polyolefin and a plasticizer to obtain a solution of the polyolefin, extrusion and cooling of a solution of the polyolefin to form a sheet, stretching the sheet and the subsequent extraction of the plasticizer from the extended sheet for formation of a microporous membrane 1 with an average pore size of 0.5-2 μm at least on one surface, (ii) further stretching the microporous membrane 1 when heating the AI for the formation of a microporous membrane 2 with an average pore size of 0.01 μm or more, and (iii) laminowanie microporous membranes 1 and 2.

JP 2003-105123 And discloses a microporous polyolefin membrane containing polyethylene with srednevekovoi molecular weight (Mw) 5×105or more as a mandatory component and with an average pore size varying in thickness, in which at least the average pore size of one of its surfaces is greater than inside or in which the average pore size of one surface more than the other surface, so that the microporous polyolefin membrane had excellent tensile strength puncture, resistance to heat shrinkage and permeability. This microporous polyolefin membrane obtained (a) by mixing a melt of the polyolefin containing polyethylene having Mw of 5×105or more as a mandatory component, with membranaceous solvent, obtained by extrusion of a melt of the mixture through the die plate, cooling extrudable melt mixture for the formation of gel-like sheet, biaxial stretching the gel-like sheet temperature distribution across the thickness, removing the solvent from the stretched gel-like sheet, stretching the resulting membrane, at least in one direction, and then heat-treated membrane at a temperature in the range of temperature dispersion of crystals polyolefin or above to temperature nigatake melting polyolefin for the formation of a microporous membrane (i), (b) stretching the above-mentioned gel-like sheet at least in one direction at a temperature lower than the temperature of the dispersion of crystals of the polyolefin and then stretching the gel-like sheet at least in one direction at a temperature in the range of temperature dispersion of crystals polyolefin or above to a temperature below the melting point of the polyolefin, and then removing the solvent from the stretched membrane for the formation of a microporous membrane (ii), and (C) laminating the microporous membranes (i) and (ii). However, in microporous membranes above link layers with different average diameter of pores are formed under different conditions of strain, but not with different concentrations of the melt mixture. Accordingly, they do not necessarily have a well-balanced permeability, mechanical properties, resistance to heat shrinkage, compressive strength, properties, disable and melting.

The purpose of the invention

In line with this objective of the present invention to provide a method of manufacturing a microporous polyethylene membrane, characterized by well-balanced permeability, mechanical properties, resistance to heat shrinkage, compressive strength, absorption capacity relative to the electrolytic solution, properties, disable the program and melting, with an average diameter of pores of varying thickness, with easy control of the distribution of the average diameter of pores in the thickness, and battery separator.

Disclosure of inventions

As a result of intensive studies on the above-mentioned purpose, the applicants have found that a microporous polyethylene membrane, characterized by well-balanced permeability, mechanical properties, resistance to heat shrinkage, compressive strength, absorption capacity relative to the electrolytic solution, properties, disable and melting, with an average diameter of pores of varying thickness may be manufactured by mixing a melt of the polyethylene resin and membranebased solvent to obtain a solution And the concentration of the resin 25-50% of the mass. and solution with a concentration of resin 10-30% of the mass. the concentration of the resin in the solution is higher than in solution, (a) the simultaneous extrusion of the resin solutions a and b through the die plate, cooling the resulting extrudate to obtain a gel-like sheet in which the resin solutions a and b are laminated, and removing membranebased solvent from the gel-like sheet, or (b) extrusion of the resin solutions a and b through separate dies, removing membranebased solvent from the obtained gel-like sheets a and b to creation the microporous polyethylene membranes a and b, and alternately laminating the microporous polyethylene membranes a and b with easy control of the average diameter of pores microporous polyethylene membrane thickness. The present invention was made on the basis of the received data.

Thus, the first method of the present invention, the microporous polyethylene membrane with an average pore diameter of varying thickness, includes the stage of mixing of the melt, at least, a polyethylene resin and membranebased solvent to obtain a solution of the polyethylene resin And the concentration of the resin 25-50% of the mass. and solution of the polyethylene resin concentration of the resin 10-30% of the mass. the resin concentration in the solution of a polyethylene resin And higher than in the solution of a polyethylene resin; simultaneously extruding solutions of polyethylene resins a and b through the die plate; cooling the resulting laminate extrudate to obtain a gel-like sheet and remove membranebased solvent from the gel-like sheet.

The second method of the present invention, the microporous polyethylene membrane with an average pore diameter of varying thickness, includes the stage of mixing of the melt, at least, a polyethylene resin and membranebased solvent to obtain a solution of the polyethylene resin And the concentration of the resin 25-50% of the mass. and solution of the polyethylene resin concentration of the resin 10-30% of the mass. the resin concentration in the solution of a polyethylene resin And higher than in the solution of polyethylene with the Ola. extruding solutions of polyethylene resins a and b through a separate die; cooling the obtained extrudates to obtain a gel-like sheets a and b; delete membranebased solvent from the gel-like sheets a and b to obtain a microporous polyethylene membranes a and b, and alternately laminating the microporous polyethylene membranes a and B.

The difference in concentration of the resin between the solutions of polyethylene resins a and b is preferably 5 wt%. or more, more preferably 10% of the mass. or more. The polyethylene resin preferably includes a polyethylene composition comprising a polyethylene ultra-high molecular weight with srednevekovoi molecular weight of 7×105or more, and high-density polyethylene with srednevekovoi molecular weight of 1×104or more and less than 5×105. The polyethylene resin may include a heat resistant resin with a melting point or glass transition temperature of 150°C or higher. Heat-resistant resin preferably is a polypropylene terephthalate or polybutylene.

The battery separator of the present invention receive the above first or second method.

Description of the preferred implementations

[1] the Polyethylene resin

Polyethylene resin, forming a microporous polyethylene membrane, which can the button be called simply as "microporous membrane", is (a) the ultrahigh-molecular weight polyethylene, (b) polyethylene, different from the ultrahigh-molecular weight polyethylene, (C) a mixture of ultrahigh-molecular weight polyethylene and the other polyethylene (polyethylene composition), (d) a mixture of any of (a) - (C) with another polyolefin different from polyethylene, polypropylene and polymethylpentene (polyolefin composition), or (e) a mixture of any of (a)-(d) with a heat-resistant resin with a melting point or a glass transition temperature Tg Of 150°C or higher (composition of heat-resistant polyethylene resin). In any case srednevekovaja molecular weight (Mw) of the polyethylene resin is preferably 1×104-1×107more preferably 1×104-5×106especially 1×104-4×106although it is not particularly critical. With polyethylene resin with a Mw of 5×106or less can be obtained microporous layer with pores of large size and high permeability.

(a) the ultrahigh-molecular weight Polyethylene

The ultrahigh-molecular weight polyethylene has a Mw 7×105or more. The ultrahigh-molecular weight polyethylene can be not only homopolymer ethylene, but also copolymers of ethylene-α-olefin, containing a small amount of another α-olefin. Other α-olefins other than ethylene, preferred are propylene, b is the tena-1, pentanol-1, hexene-1, 4-methylpentene-1, octene, vinyl acetate, methyl methacrylate and styrene. Mw of ultrahigh-molecular weight polyethylene is preferably 1×106-15×106more preferably 1×106-5×106. Not only one type of ultrahigh-molecular weight polyethylene, but also a mixture of two or more polyethylene ultra-high molecular weight can be used. The mixture can be, for example, a mixture of two or more polyethylene ultra-high molecular weight with different Mws.

(b) the Polyethylene other than the ultrahigh-molecular weight polyethylene

The polyethylene other than the ultrahigh-molecular weight polyethylene with Mw 1×104or more and less than 5×105preferably is at least one selected from the group consisting of polyethylene, high density polyethylene, intermediate density, branched low-density polyethylene and linear low density polyethylene, the preferred high density polyethylene. Polyethylene having Mw of 1×104or more and less than 5×105can be not only homopolymer ethylene, but also copolymers containing a small amount of another α-olefin such as propylene, butene-1, hexene-1, etc. Such copolymers preferably obtained using a catalyst with a single center is m polymerization on the metal. Can be used not only one type of polyethylene other than the ultrahigh-molecular weight polyethylene, but also a mixture of two or more polyethylenes, other than the ultrahigh-molecular weight polyethylene. The mixture can be, for example, a mixture of two or more polyethylenes, high-density with different Mws, a mixture of such polyethylene, intermediate density, a mixture of such low density polyethylenes, etc.

(c) the Polyethylene composition

The polyethylene composition is a blend of ultrahigh-molecular weight polyethylene with Mw 7×105or more and another polyethylene, which is at least one selected from the group consisting of polyethylene, high density polyethylene, intermediate density, branched low-density polyethylene and linear low density polyethylene. The ultrahigh-molecular weight polyethylene and the other polyethylene can be those described above. Mw other polyethylene is preferably from 1×104or more to less than 5×105. Molecular mass distribution [srednevekovaja molecular weight/srednekislye molecular mass (Mw/Mn)] this polyethylene composition can be easily adjusted depending on applications. The polyethylene composition preferably is above whom is azizia of ultrahigh-molecular weight polyethylene and high density polyethylene. The content of the ultrahigh-molecular weight polyethylene in the polyethylene composition is preferably 1% of the mass. or more, more preferably 2-50% of the mass. with respect to 100 wt%. all polyethylene composition.

(d) polyolefin composition

Polyolefin composition is a blend of ultrahigh-molecular weight polyethylene, the other polyethylene or the polyethylene composition and a polyolefin other than polyethylene, polypropylene and polymethylpentene. The ultrahigh-molecular weight polyethylene, the other polyethylene and the polyethylene composition can be the same as described above.

The polyolefin other than polyethylene, polypropylene and polymethylpentene may be at least one selected from the group consisting of polybutene-1, polypainting-1, polyacene-1, polyctena-1, polyvinyl acetate, polymethylmethacrylate, polystyrene and copolymers of ethylene-α-olefin, each of which has a Mw of 1×104-4×106and of polyethylene wax with a Mw of 1×103-1×104. Polybutene-1, polypenco-1, polymixin-1, policen-1, polyvinyl acetate, polymethyl methacrylate and polystyrene can be not only homopolymers, but also copolymers containing other α-olefins. The content of the polyolefin other than polyethylene, polypropylene and polymethylpentene, is preferably 20 wt%. or m is it more preferably 10% of the mass. or less, relative to 100 wt%. all polyethylene composition.

(e) heat-Resistant composition of polyethylene resin

Heat-resistant composition of the polyethylene resin is a mixture of any of the above (a)-(d) and the heat-resistant resin with a melting point or a glass transition temperature Tg Of 150°C. or higher. Heat-resistant resin is preferably a crystalline resin (including semi-crystalline resin with a melting point of 150°C or higher, or an amorphous resin with a Tg Of 150°C. or higher. The melting point and Tg can be measured in accordance with JIS K.

As a battery separator formed by the microporous membrane comprising a polyethylene resin containing a heat resistant resin and has improved melting temperature, the batteries provided with improved storage stability at high temperature. Heat-resistant resin is dispersed in the form of spherical or ellipsoidal fine particles in homopolymer or composition described above in (a)-(d), mixing of the melt. Fiber phase polyethylene (phase of the ultrahigh-molecular weight polyethylene, the other polyethylene or the polyethylene composition) are oxidized fine particles of heat-resistant resin as the nuclei under tension, thus forming a hair-pores containing melkodispersnye particles in the center. As a result, the battery separator formed by the microporous polyethylene membrane, gets improved compression resistance and sorption capacity with respect to the electrolytic solution. The dimensions of the spherical fine particles and the principal axes of the ellipsoid fine particles preferably be 0.1-15 μm, more preferably 0.5 to 10 μm, especially 1 to 10 μm.

When applied crystalline resin with a melting point below 150°C or amorphous resin with a Tg of lower than 150°C., the resin is highly dispersed in homopolymer or composition described in (a)-(d) above, by mixing the melt, without forming fine particles of the proper diameter. The result is the formation of small holes due to the splitting of the fine resin particles as the core, which does not allow to expect a further improvement in resistance to compression and absorption capacity with regard to the electrolytic solution. The upper limit of the melting point or Tg of the heat-resistant resin is preferably 350°C. in terms of Miscibility with homopolymers or composition described in (a)-(d) above, although not especially critical. The melting point or Tg of the heat-resistant resin preferably is 170-260°C.

Mw heat-resistant resin is preferably 1×103-1×106more preferably 1×104 -7×105though varies depending on the type of resin. Heat-resistant resin with a Mw of less than 1×103highly dispersed in homopolymer or composition described in (a)-(d) above, and loses the ability to form fine particles. Heat-resistant resin with a Mw of more than 1×106cannot be easily mixed with homopolymers or composition described in (a)-(d) above.

The content of the heat-resistant resin is preferably 3-30 wt%. more preferably 5-25 wt%. with respect to 100 wt%. all polyethylene composition is heat-resistant resin. When this content is more than 30% of the mass. the membrane has a low tensile strength puncture, tensile strength and smoothness.

Specific examples of the heat resistant resin include polyesters, polypropylene (PP), polymethylpentene [PMP or TPX (transparent polymer X)], fluorinated resins, polyamides (PA, melting point 215-265°C), Polyarylamide (PAS), polystyrene (PS, melting point 230°C.), polyvinyl alcohol (PVA, the melting point of 220-240°C), polyimides (PI, Tg 280°C or higher), polyamidimide (PAI, Tg 280°C), polyethersulfone (PES, Tg 223°C), peek (REEK, the melting point of 334°C.), polycarbonates (PC, melting point 220-240°C), cellulose acetate (melting point 220°C.), cellulose triacetate (the melting point of 300°C.), polysulfone (Tg 190°C), polyetherimide (melting point 216°C), etc. heat-Resistant resin may comprising the ü not only of a single component resin, but several components of the resin.

(1) Polyesters

Polyesters include polybutylene terephthalate (RHT, melting point about 160-230°C), polyethylene terephthalate (PET), a melting point of about 250-270°C), naftalin polyethylene (PEN, the melting point of 272°C.), naftalin polybutylene (PBN, melting point 245°C), etc., RHT is preferred.

RHT is essentially saturated polyester obtained from 1,4-butanediol and terephthalic acid. Within ranges not deteriorating the properties such as heat resistance, compression resistance, resistance to heat shrinkage, etc. as comonomers may be included other diols other than 1,4-butanediol, and other carboxylic acid other than terephthalic acid. Such dialami can be, for example, ethylene glycol, diethylene glycol, neopentylglycol, 1,4-cyclohexanemethanol etc. Dicarboxylic acids can be, for example, isophthalic, sabotinova, adipic, azelaic, succinic acid, etc. in a Specific example RHT resin forming RHT can be, for example, Homo-RHT resin, commercially supplied by Toray Industries, Inc. under the trademark "Toraycon". RHT may be composed not only of a single component, but also of several RHT components of the resin. Mw PBT, in particular, is 2×104-3×105.

(2) Polypropylene

PP can be not only homop what limera, but also block or statistical copolymer containing other α-olefins or diolefine. Other olefins are preferably ethylene or α-olefins with 4 to 8 carbon atoms. α-Olefins with 4 to 8 carbon atoms include, for example, 1-butene, 1-hexene, 4-methyl-1-penten etc. Diolefine preferably have from 4 to 14 carbon atoms. Diolefine from 4-14 carbon atoms include, for example, butadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene etc. the Contents of another olefin or diolefin preferably less than 10 mol%. with respect to 100 mol%. propylene copolymer.

Mw PP in particular is 1×105-8×105. Molecular weight distribution (Mw/Mn) RR preferably is 1.01 to 100, more preferably 1.1 to 50. PP may be a single substance or a composition of two or more types of PP. The melting point of PP is preferably 155-175°C. such As PP dispersed in the polyethylene resin in the form of fine particles, shape and size, as described above, the fibers constituting the microporous membrane, split fine particles in PP as nuclei, thus giving the pores formed by the hairy holes.

(3) Polymethylpentene

PMP is essentially any of the polyolefins obtained from 4-methyl-1-pentene, 2-methyl-1-pentene, 2-methyl-2-pentene, 3-methyl-1-pentene-methyl-2-pentene, and preferred is 4-methyl-1-penten a homopolymer. PMP may be a copolymer containing a small amount of α-olefin other than methylpentene within the range not deteriorating the properties such as heat resistance, compression resistance, resistance to heat shrinkage, etc. α-Olefins other than methylpentene are, respectively, ethylene, propylene, butene-1, pentanol-1, hexene-1, octene, vinyl acetate, methyl methacrylate, styrene, etc. PMP typically has a melting point 230-245°C. Mw PMP, in particular, is 3×105-7×105.

(4) Pteridomania resin

Pteridomania resin include polyvinylidene fluoride (PVDF, melting point: 171°C), polytetrafluoroethylene (PTFE melting point 327°C), a copolymer of a tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA, the melting point of 310°C), a copolymer of a tetrafluoroethylene-HEXAFLUOROPROPYLENE-PERFLUORO(propylvinyl ether) (ORE, melting point 295°C), a copolymer of a tetrafluoroethylene-HEXAFLUOROPROPYLENE (FEP, melting point 275°C), the copolymer of ethylene-tetrafluoroethylene (ETFE, melting point 270°C), etc.

Fluorinated resin is preferably PVDF. PVDF can be a copolymer (copolymer vinylidenefluoride) with other olefins. The content of vinylidenefluoride in the copolymer vinylidenefluoride preferably is 75% of the mass. or more, more preferably 90% of the mass. or more. The monomers copolymerisate with vinylidenefluoride, include HEXAFLUOROPROPYLENE, tetrafluoroethylene, triptorelin, ethylene, propylene, isobutylene, styrene, vinyl chloride, vinylidenechloride, diperchlorate, wikiformat, vinyl acetate, finalproject, vinylboronate, acrylic acid and its salts, methyl methacrylate, alismataceae, Acrylonitrile, Methacrylonitrile, N-butoxyaniline, ZIOC scientists Isopropenyl acetate, etc. Preferred copolymer vinylidenefluoride is a copolymer, a HEXAFLUOROPROPYLENE-vinylidenefluoride.

(5) Polyamides

RA is preferably at least one selected from the group consisting of polyamide 6 (6-nylon), polyamide 66 (6,6-nylon), polyamide 12 (12-nylon) and amorphous polyamides.

(6) Polyarylamide

PAS is preferably polyster (PPS) with a melting point of 285°C. PPS can be linear or branched.

(f) Molecular weight distribution Mw/Mn

Mw/Mnis a measure of the distribution of molecular masses. the higher the value, the wider the distribution of molecular masses. Although not critical, Mw/Mnthe polyethylene resin is preferably 5 are 300, more preferably 10-100, when the polyethylene resin is composed of ultrahigh-molecular weight polyethylene, the other polyethylene or the polyethylene composition. When Mw/Mn- less there are components from excessively high molecular weight, which leads to difficulty in melt extrusion. When Mw/Mnmore than 300, there are components with extremely low molecular weight, which results in obtaining a microporous membrane with reduced strength. Mw/Mnpolyethylene (homopolymer or copolymer of ethylene-α-olefin) can accordingly be governed by a multi-stage polymerization. Multi-stage polymerization method is preferably a method of polymerization with two stages, including the education component of the polymer with high molecular weight in the first stage and the education component of the polymer with a low molecular weight in the second stage. In the case of the polyethylene composition, the more Mw/Mnthe greater the difference in the Mwbetween the ultrahigh-molecular weight polyethylene and the other polyethylene, and Vice versa. Mw/Mnthe polyethylene composition may accordingly be governed by the molecular weight and the percentage of each component.

[2] the Method of producing microporous polyethylene membrane

(a) the First way to obtain

The first method in accordance with the present invention, the microporous polyethylene membrane includes a stage (1) (i) mixing the polyethylene melt the resin and membranebased solvent to obtain a solution of the polyethylene resin And the concentration of the resin 25-50 wt. -%, (ii) mixing in the melt of the polyethylene resin and membranebased solvent to obtain a solution of a polyethylene resin concentration of the resin 10 to 30 wt. -%, the resin concentration in the solution is lower than in the solution And, (2) simultaneous extrusion of solutions of polyethylene resins a and b through the die plate, (3) cooling the resulting laminate extrudate for the formation of gel-like sheet, (4) removing membranebased solvent from the gel-like sheet, and (5) drying the resulting membrane. Before stage (4), if necessary, can be carried out stage stretching, shrinking, processing hot roller and processing of hot solvent. After stage (5) can be carried out stage of re-stretching, handling hot solvent, heat treatment, joining ionizing radiation, hydrophilization, surface coating, etc.

(1) preparation of a solution of polyethylene resin

(i) obtaining a solution of a polyethylene resin And

The above polyethylene resin (referred to as "polyethylene resin And, if not otherwise specified) and suitable membranebased solvent are mixed in the melt to obtain a solution of a polyethylene resin (hereinafter referred to for simplicity as "solution of resin A"). The resin solution may contain various additives, such as fillers, antioxidants, will the Fort worth ultraviolet light, parting agent, pigments, dyes, etc. and, if necessary, in amounts that do not impair the positive effects of the present invention. Fine powder of silica, for example, can be added as a pore-forming means.

Membranebased the solvent can be a liquid or a solid. Liquid solvents can be aliphatic or cyclic hydrocarbons such as Noonan, Dean, decalin, n-xylene, undecane, dodecane, liquid paraffin, etc. and fractions of mineral oil having a boiling point corresponding to the above-mentioned hydrocarbons. To obtain a gel-like sheet with a stable liquid solvent, the preferred non-volatile liquid solvents, such as liquid paraffin. Solid solvents preferably have a melting point of 80°C or below. Such solid solvents are paraffin wax, arrowy alcohol, stearyl alcohol, dicyclohexyltin etc. Liquid solvent and a solid solvent can be used in combination.

The viscosity of the liquid solvent is preferably 30-500 cSt, more preferably 50-200 cSt at 25°C. When the viscosity at 25°C. is less than 30 cSt, the resin solution And unevenly extruded through an edge of the die, resulting in difficulty in blending. Viscosity of more than 500 cSt complicates the removal of the liquid solvent.

The fillers can be inorganic or organic fillers. Inorganic fillers include silica, alumina, silica-alumina, zeolite, mica, clay, kaolin, talc, calcium carbonate, calcium oxide, calcium sulfate, barium carbonate, barium sulfate, magnesium carbonate, magnesium sulfate, magnesium oxide, diatomaceous earth, glass powder, aluminum hydroxide, titanium dioxide, zinc oxide, satinet, acidic clay, etc. and Inorganic fillers can be used separately or in combination. Among them, preferred are silicon dioxide and/or calcium carbonate. Organic fillers are preferably made of the above heat-resistant resins.

The shape of the filler particles is not particularly critical, but can be appropriately selected, for example, spherical or sprayed fillers and spherical fillers are preferred. The particle size of the fillers is preferably 0.1 to 15 μm, more preferably 0.5 to 10 μm. Fillers can be surface treated. Means of surface treatment of fillers include, for example, various silane binder, aliphatic acids such as stearic acid or its derivatives, etc.

The use of fillers improves the sorption ability towards electrolitics the th solution. Apparently, this is due to the fact that with the added fillers, fibers forming the microporous membrane, split filler particles as the core, thus forming hair-like openings (pores) and thus increase the amount of holes (pores). It is assumed that the particles of filler are held on such day.

The amount of filler added is preferably 0.1 to 5 mass. parts, more preferably 0.5 to 3 mass. parts, relative to 100 mass. parts of the total amount of the polyethylene resin and fillers. When this content is more than 5 mass. parts, the membrane is characterized by low strength piercing and affects the deformation during compression, resulting in increased separation of the fillers during cutting. A large number of powder obtained by separating fillers, probably forming defects, such as pitting, holes, stains (pollution), etc. in the products of the microporous membrane.

Although not especially critical, homogeneous mixing of the melt is preferably carried out in a twin screw extruder. This method is suitable for obtaining highly concentrated solution of a polyethylene resin A. the temperature of the melt mixing is preferably from the melting point TMandpolyethylene resin plus 10°C to the melting point TMthe plus 100°C. the melting Point TMandpolyethylene resin And is a melting point (a) of the ultrahigh-molecular weight polyethylene, (b) other polyethylene other than the ultrahigh-molecular weight polyethylene, or (C) the polyethylene composition, when the polyethylene resin And is any of (a)-(C). When the polyethylene resin And is (d) polyolefin composition or (e) the composition of the heat-resistant polyethylene resin, the melting point TMA of the polyethylene resin is a melting point above (a)to(C)contained in (d) polyolefin composition or (e) the composition is heat-resistant polyethylene resin. The ultrahigh-molecular weight polyethylene described above in [1] (a)the polyethylene other than the ultrahigh-molecular weight polyethylene described above in [1] (b), and the polyethylene composition described in [1] (C), have a melting point of about 130-140°Scootertechno, the temperature of mixing of the melt is preferably in the range of 140-250°C., more preferably in the range of 170-240°C.

When the polyethylene resin And is composed of heat-resistant polyethylene resin, the temperature of mixing of the melt preferably is in the range from the melting point TMandcrystalline heat-resistant resin or Tg amorphous, thermally stable resin to the melting point TMandplus 10°C, depending on the type of heat-resistant resin. For example, when the heat-resistant resin is PP with a melting point 155-175°C or RHT with a melting point of about 160-230°C, the temperature of the melt mixing is preferably 160-260°C., more preferably 180 to 250°C.

Membranebased solvent can be added before the mixing of the melt or to be loaded into the extruder in an intermediate position during mixing of the melt, although the latter is preferable. When mixing of the melt, it is preferable to add an antioxidant to prevent oxidation of the polyethylene resin A.

The ratio L/D, where L and D respectively represent the length and diameter of the screw in the twin screw extruder is preferably from 20 to 100, more preferably 35-70. When L/D is less than 20, not achieved sufficient mixing of the melt. When L/D is more than 100, for too long, the resin solution And is present in the extruder. The screw may be of known form, although this is not particularly critical, the Inner diameter of the cylinder of the twin screw extruder is preferably 40-100 mm

The resin concentration in the resin solution And is 25-50% of the mass. preferably 25-45% of the mass. with respect to 100 wt%. total amount of the polyethylene resin and membranebased solvent. When the concentration of the resin is less than 25% of the mass. the microporous layer And, on sovanny the resin solution And, unlikely to have a dense structure in the resulting microporous membrane. When the resin concentration is more than 50 wt%. gel press the product has poor formability.

(ii) obtaining a solution of a polyethylene resin

The solution of the polyethylene resin (hereinafter referred to as "resin solution") may be the same as described above except that the resin concentration of the polyethylene resin (referred to as "polyethylene resin", unless otherwise specified) is 10-30% of the mass. with respect to 100 wt%. total amount of the polyethylene resin and membranebased solvent and lower than in the solution of resin A. the resin Concentration is less than 10% of the mass. it is undesirable to cause a decrease in performance. In addition, there is significant swelling and narrowing of the outlet of the die during extrusion of the resin solution, resulting in decrease of formemost and its strength gel-like molding parts. The concentration of the resin is more than 30% of the mass. it difficult to obtain a microporous layer of the resin solution In coarse-grained structure in the resulting microporous membrane. The preferred concentration of the resin is from 10 to 25% of the mass.

The temperature of mixing of the melt is preferably in the range from the melting point TMbthe polyethylene resin + 10°C to point plale the Oia TM bplus 100°C. When the polyethylene resin is (a) the ultrahigh-molecular weight polyethylene, (b) polyethylene other than the ultrahigh-molecular weight polyethylene, or (C) the polyethylene composition, the melting point TMbthe polyethylene resin is the melting point of one of them. When the polyethylene resin is In (d) polyolefin composition or (e), the composition of the heat-resistant polyethylene resin, the melting point TMbis the melting point of any of the above (a)to(C)contained in (d) polyolefin composition, or (e) the composition is heat-resistant polyethylene resin. When the polyethylene resin In the composition is heat-resistant polyethylene resin, the temperature of mixing of the melt preferably is in the range from the melting point TMbcrystalline, heat-resistant resin or Tg amorphous, thermally stable resin to the melting point TMbplus 100°C, depending on the type of heat-resistant resin.

(iii) the Difference in concentration of the polyethylene resin a and b

With a solution of resin And having a higher concentration of resin than the resin solution, the resulting microporous polyethylene membrane has a gradient structure in which the average diameter of pores in the microporous layer In more than microporous layer A. Accordingly, the crust is ASEE invention can offer a microporous polyethylene membrane with an average pore diameter of, varying thickness without stretching the gel-like sheet. The difference in the concentration of the resin between the resin solutions a and b is preferably 5 wt%. or more, more preferably 10% of the mass. or more.

(2) Extrusion

Mixed in the melt of the resin solutions a and b supplied from separate extruders in the die plate through which simultaneously ekstragiruyut. Simultaneous extrusion of the resin solutions a and b, in which two solutions are combined in layers in one filiere, ekstragiruyut in the form of a sheet (compound filiere), multiple extruders are connected with one villeroi. Alternatively, when both solution ekstragiruyut in the form of a sheet of the individual dies and then laminated (connection outside the die), each extruder associated with each Villeroy. Preferred is a compound in filiere.

While extrusion can be used the way flat Villeroy way or blown. To achieve the connection in filiere in any way can be used a method of supplying solution for each pipeline associated with each Villeroy for multilayer formation, and their flat lamination on the edge of the die (the method with multiple pipelines), or how flat laminating solutions and the subsequent filing of the obtained laminate in the die plate (block method). Because of the method with several pipes the wires and block the way in themselves known, their detailed description will be omitted. For example, the famous flat filler or blow can be used for the formation of the multilayer membrane. Flat filler for multilayer formation preferably has a gap of 0.1-5 mm When the connection is made outside of the Spinneret way flat Villeroy, extrudable through each die plate solutions in the form of a sheet can be laminated under pressure between a pair of rolls. In any of the ways described above, the die plate in the extrusion process is heated to a temperature of 140-250°C. the Speed of extrusion of the hot solution is preferably 0.2 to 15 m per minute. Adjusting the amount of each solution extrudable resin And can determine the ratio of the microporous layer And the microporous layer of the Century

(3) the Formation of gel-like sheet

Get a flat extrudate is cooled to obtain a gel-like sheet. The cooling is preferably carried out, at least to the temperature of gelation at a speed of 50°C per minute or more. This cooling provides a fixed microphase separation between the polyethylene resins a and b, called membranebased solvent. The cooling is preferably up to 25°C or below. Usually slow cooling gives a gel-like sheet of coarse-grained highly organized structure with Bo is ishimi elementary pseudoacacia, while high speed cooling gives densely arranged unit cell. The cooling rate of less than 50°C/min increases the crystallization, which complicates the formation of tensile gel-like sheet. The cooling method may be a method of bringing the extrudate into direct contact with a cooling medium such as cooling air, cooling water, etc., a way of bringing the extrudate into contact with a cooling roller, etc.

When the polyethylene resin a and b are any of the above [1] (a)-(e), the temperature of the cooling roll is preferably in the range from TC minus 115°C to TC, where TC is the lowest temperature of crystallization TCandpolyethylene resins and the crystallization temperature TCbpolyethylene resin C. the Temperature of the cooling roll above the crystallization temperature TC does not provide a sufficiently rapid cooling. The temperature of the cooling roll more preferably is in the range from the crystallization temperature TC minus 110°C. to the crystallization temperature TC minus 10°Skoda polyethylene resin And, is (a) the ultrahigh-molecular weight polyethylene, (b) polyethylene other than the ultrahigh-molecular weight polyethylene, or (C) the polyethylene composition, the crystallization temperature TCand, Cubthe polyethylene is new resin And, In is the temperature of crystallization of any of (a)-(C). When the polyethylene resin And, is (d) polyolefin composition or (e), the composition of the heat-resistant polyethylene resin, the crystallization temperature TCand, Cubpolyethylene resin And, In is the temperature of crystallization of any of the above (a)to(C)contained in (d) polyolefin composition or (e) the composition is heat-resistant polyethylene resin.

The crystallization temperature is measured in accordance with JIS K. The crystallization temperature of the ultrahigh-molecular weight polyethylene described in [1] (a) above, the polyethylene other than the ultrahigh-molecular weight polyethylene described in [1] (b) above, and the polyethylene composition described in [1] (C) above, is usually 102-108°C. Accordingly, the temperature of the cooling roll is in the range from -10°C to 105°C, preferably in the range from -5°C to 95°C. the contact Time between the cooling roller and the sheet is preferably 1-30 seconds, more preferably 2-15 seconds.

(4) Remove membranebased solvent

Membranebased the solvent is removed (washed away) with the use of the washing solvent. Since phase polyethylene resins a and b is separated from the phase membranebased solvent, removing membranebased solvent gives a MIC the porous membrane, consisting of fibers, forming a thin, three-dimensional structure with three-dimensional irregular communicating pores (voids).

Cleaning solvents may be volatile solvents such as saturated hydrocarbons, such as pentane, hexane, heptane and so on; chlorinated hydrocarbons such as methylene chloride, carbon tetrachloride and so on; ethers such as diethyl ether, dioxane and so on; ketones such as methyl ethyl ketone and so on; linear fluorocarbons, such as trifluoroethane,6F14C7F16and so on; cyclic fluorocarbons, such as C5H3F7etc.; hydrotherapie, such as C4F9OCH3C4F9OC2H5and so on; and perforativni, such as C4F9OCF3C4F9OC2F5and so These cleaning solvents have low surface tension, for example 24 mn/m or less at 25°C. the Use of the washing solvent with low surface tension suppresses the shrinkage of the pore-forming mesh structure due to surface tension at the phase boundaries of the gas-liquid during drying after washing, thus providing a microporous membrane with high porosity and permeability.

Rinse the gel-like sheet can be carried out by immersion in a detergent the first solvent, method of irrigation, cleaning solvent, or a combination. The amount of the washing solvent is preferably 300-30000 masses. parts per 100 mass. parts of the membrane. The temperature of the wash can usually be 15-30°C and, if necessary, can be carried out hot washing. The temperature of the hot washing is preferably 80°C. or lower. Washing with wash solvent is preferably carried out until the number of remaining membranebased solvent becomes less than 1% of the mass. from added.

(5) Drying the membrane

Microporous polyethylene membrane obtained by removing membranebased solvent, and then dried by the method of heating, a method of blowing etc. Temperature drying is preferably equal to or lower than the temperature of the dispersion of crystals Tcd, which is lower than the temperature of the dispersion of crystals Tcdathe polyethylene resin and the dispersion temperature crystals Tcdbpolyethylene resin, in particular 5°C or even lower, than the temperature of the dispersion of crystals Tcd. When the polyethylene resin a, is (a) the ultrahigh-molecular weight polyethylene, (b) polyethylene other than the ultrahigh-molecular weight polyethylene, or (C) the polyethylene composition, the temperature of the dispersion of crystals Tcda, Tcdbpolyethylene resins a, b is the rate of which the temperature dispersion of the crystals of the above (a)-(C). When the polyethylene resin And, is (d) polyolefin composition or (e) the composition of the heat-resistant polyethylene resin, the temperature dispersion of the crystals is determined by the above-mentioned (a)to(C)contained in (d) polyolefin composition or (e) the composition is heat-resistant polyethylene resin. The temperature dispersion of the crystals is determined by measuring the temperature dependence of dynamic viscoelasticity according to ASTM D 4065. The ultrahigh-molecular weight polyethylene [1] (a)the polyethylene other than the ultrahigh-molecular weight polyethylene [1] (b), and the polyethylene composition [1] (C) have a temperature dispersion of the crystals in the range of about 90-100°C.

The drying is conducted until the percentage of remaining washing solvent will preferably be 5% of the mass. or less, more preferably 3 wt%. or less relative to 100% by weight of the microporous membrane (dry weight). Insufficient drying is undesirable reduces the porosity of the microporous membrane in the subsequent stages of re-stretching and heat treatment, leading, thus, to the poor permeability.

(6) an Optional stage before removing membranebased solvent

Before stage (4) remove membranebased solvent can be carried out any of the stages of stretching, shrinking, processing and hot roller and processing of hot solvent.

(i) Stretching

After heating the gel-like sheet is preferably stretched with a given ratio of the stretching method on the frame, calendering, blowing, rolling, or a combination. Because the gel-like sheet contains membranebased solvent, it can be uniformly stretched. Although stretching may be uniaxial or biaxial, biaxial stretching is preferable. Biaxial stretching may be simultaneous biaxial stretching, sequential stretching or multi-stage stretching (for example, a combination of simultaneous biaxial stretching and sequential stretching), although the simultaneous biaxial stretching is particularly preferable.

The stretching ratio is preferably 2 times or more, more preferably 3-30 times in the case of uniaxial tension. In the case of biaxial stretching, the stretching ratio is at least 3 times in both directions, with a magnification of preferably square 9 times or more, more preferably 25 times or more. The increase in the area of less than 9 times leads to insufficient tension, not allowing to obtain high-modulus, high-strength microporous membrane. When the increase in the area more than 400 times, there are limitations in the equipment, performing operations on rastyajeniya etc.

The stretching temperature is preferably equal to or below the melting point TM + 10°C., more preferably in the range of temperature dispersion of crystals Tcd or more to a temperature below the melting point TM, the melting point Tm is the lower of the melting points TMandpolyethylene resin and TMbpolyethylene resin C. When the stretching temperature exceeds the melting point Tm + 10°C, the resin is melted, so that the tension cannot Orient the molecular chains. When it is lower than the temperature of the dispersion of crystals Tcd, the resin is insufficiently softened that makes probable rupture of membranes under tension, which does not allow to achieve high tension. As described above, the ultrahigh-molecular weight polyethylene described above in [1] (a)the polyethylene other than the ultrahigh-molecular weight polyethylene described above in [1] (b), and the polyethylene composition described in [1] (C)have a temperature dispersion of crystals of about 90-100°Scootertechno, the stretching temperature is usually in the range of 90-140°C., preferably in the range of 100-130°C.

The above tensile splitting between the polyethylene crystalline plates, making the plastic phase (phase of the ultrahigh-molecular weight polyethylene, phase polyethylene or phase polyethylene component is icii), more fine-grained with a large number of fibers. Fibers form a three-dimensional mesh structure (three-dimensional and irregularly connected mesh structure). In the layer containing the composition of the heat-resistant polyethylene resin, the fiber is split fine particles of heat-resistant polymer as nuclei, thus forming hair-like pores that hold the fine particles.

Depending on the desired properties of the stretching can be carried out with a temperature gradient across the thickness to obtain a microporous membrane with a higher mechanical strength. This method specifically described in JP 3347854.

(ii) Shrinking

The gel-like sheet can be subjected to heat shrinkage. Shrinking can change the pore size and porosity of the microporous membrane, and especially to increase the pore size of the microporous layer C. the Heat treatment is carried out by a method using a frame, rolls or rolling. The shrinking is carried out in the temperature range from the melting point Tm + 10°C. or below, preferably the temperature of the dispersion of crystals Tcd, up to the melting point TM.

(iii) Processing the hot roller

At least one surface of the gel sheet may be brought into contact with a hot roller (hot roller) to increase the diameter of the pores near the surface. The diameter of pores is near the surface and the thickness of the layer with a larger pore size can be controlled by adjusting the temperature of the roll, time of contact of the membrane with a roller, the ratio of the area of contact of the membrane with a roller, etc.

The roll temperature is preferably in the range of temperature dispersion of crystals Tcd plus 10°C or above to a temperature below the melting point Tm. Processing hot roller is preferably in a gel-like sheet. Stretched upon heating the gel-like sheet is preferably cooled to a temperature below the temperature of the dispersion of crystals Tcd before contact with a hot roller.

Roll may have a smooth or rough surface. Smooth roller may be of rubber or metal roller. Hot roll may have a function of suction gel-like sheet. When the gel sheet is in contact with a hot roller with hot oil on the surface, high efficiency heating and the resulting membrane has a larger average diameter of the pores near the surface. Hot oil can be the same as membranebased solvent. Using satyayuga roll can control the amount of membranebased solvent, are on the roll.

(iv) Processing of hot solvent

The gel-like sheet can be processed in a hot solvent. Processing of hot solvent preferably is held in the stretched gel-like sheet. Dissolve the Lee, suitable for hot working, are preferably the above-mentioned liquid membranophone solvents, more preferably liquid paraffin. Solvents for hot working may be the same or different from membranebased solvent used for the solution of resin a and B.

A method of processing hot solvent is not particularly critical provided that the gel-like sheet comes into contact with a hot solvent. It includes, for example, the method of direct contact of the gel-like sheet with a hot solvent (for simplicity called "direct method", if not specified otherwise), the method of contacting the gel-like sheet with a cold solvent, followed by heating (for simplicity called "indirect method", if not specified otherwise), etc. Direct method involves immersing the gel-like sheet in a hot solvent, spraying the hot solvent into the gel-like sheet, a method of applying a hot solvent into the gel-like sheet, and so on, and the immersion is preferred. In the indirect method, gel-like sheet is dipped in the cold solvent, is sprayed him a cold solvent or put him a cold solvent and then brought into contact with a hot roller heated in a furnace or immerse in hot RA the maker.

The pore size and porosity of the microporous membrane can be modified by the appropriate job temperature and processing time hot solvent. In particular can be increased pore size in the coarse-grained layer structure (microporous layer). The temperature of the hot solvent is preferably in the range of temperature dispersion of crystals Tcd to the melting point Tm + 10°C. In particular, the temperature of the hot solvent is preferably 110-140°C., more preferably 115-135°C. the contact Time is preferably 0.1 seconds to 10 minutes, more preferably 1 second to 1 minute. When the temperature of the hot solvent temperature dispersion of crystals Tcd or when the contact time is less than 0.1 seconds, the processing of hot solvent essentially has no effect, only slightly improving the permeability. When the temperature of the hot solvent above the melting point Tm + 10°C or when the contact time is more than 10 minutes, the strength of the microporous membrane is undesirable reduced or the diaphragm is torn.

Such processing hot solvent fiber formed under tension, have the structure of the leaf veins, which stallabrass fibers are relatively thick. Respectively can be obtained microporous membrane with pores of large size and excellent contrast ratio, the Noah strength and permeability. The term "in the form of leaf veins" means that the fibers have thick trunks and thin fibers originating from them, forming a complex network structure.

Although the solvent remaining in the processing of hot solvent is removed by washing after handling hot solvent, it can be removed together with membranebased solvent.

(7) an Optional stage after stage drying

After the stage of drying (5) can be carried out in the stage of re-stretching, heat treatment, treatment with a hot solvent, crosslinking with ionizing radiation, hydrophilization, surface coating, etc.

(i) Re-stretching

Microporous membrane obtained by washing and drying the stretched gel-like sheet, preferably again stretch, at least in one direction. Re-stretching may be carried out in the same way the tension on the frame, as described above, etc. when heated membrane. Re-stretching may be uniaxial or biaxial. Biaxial stretching may be either simultaneous biaxial stretching or sequential stretching, although preferably simultaneous biaxial stretching.

The temperature of the re-stretching is preferably equal to the melting point Tm or lower, more preferably in the range of temperature display is rsii crystals Tcd to the melting point TM. When the temperature of the re-stretching is greater than the melting point TM, deteriorating the resistance to compression and there is a large heterogeneity in the properties (in particular, air permeability) in width when stretched in the transverse direction (TD). When the temperature of the re-stretching temperature dispersion of crystals Tcd, polyethylene resin and insufficiently plasticized, so that the membrane tears easily under tension, which prevents the achievement of a homogeneous strain. In particular, the temperature of the re-stretching is typically in the range 90-135°C, preferably in the range of 95-130°C.

The ratio of re-stretching in one direction is preferably 1.1 to 2.5 times to create a microporous membrane with a larger pore size and improved compression resistance. In the case of uniaxial tension, for example, the ratio of re-stretching is 1.1 to 2.5 in the direction of the MD or TD. In the case of biaxial stretching ratio of the second stretching is 1.1 to 2.5 times in both directions of MD and THOSE. When biaxial stretching, the stretching ratio may be the same or different in the direction of MD and TD, while it is 1.1 to 2.5 times, although it is preferable the same multiplicity. When this ratio less than 1.1 times, there can be obtained a sufficient resistance to compression. When this fold is to be more than 2.5 times, high probability of rupture and low resistance to heat shrinkage of the membrane. The multiplicity of repeated stretching more preferably 1.1-2.0 times.

(ii) Heat treated

The dried membrane is preferably subjected to heat treatment. Heat treatment stabilizes the crystals and makes a uniform plate crystals. The heat treatment may be carried out by shrinking and/or annealing. Shrinking may be similar to those described above.

The annealing may be carried out using a belt conveyor furnace or air blowing in addition to the way to the frame on rollers or rolling. The annealing is conducted at a temperature equal to or below the melting point TM, preferably at a temperature in the range from 60°C to the melting point Tm minus 10°C. Such annealing provides a high-strength microporous membrane with good permeability. Shrinking and annealing can be combined.

(iii) Processing of hot solvent

The dried membrane can be treated with a hot solvent. Processing of hot solvent may be the same as described above.

(iv) cross-Linking of membrane

The dried membrane can be subjected to the stitching ionizing radiation α-rays, β-rays, γ-rays, electron beam, etc. the electron beam Irradiation is preferably carried out at 0.1 to 100 Mrad and uscgaux the voltage 100-300 kV. Cross-linking increases the temperature of the melt multilayer microporous polyethylene membrane.

(v) Hydrophilidae

The dried microporous membrane can be hydrophilization. Hydrophilicity processing may be processing with the purpose of grafting monomer, the processing of surface-active substance, the treatment by corona discharge, etc. Processing with the grafting monomer is preferably carried out after stitching.

In the case of processing of a surface-active substance can be used any of nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants, but nonionic surfactants are preferred. The microporous membrane is dipped in a solution of surfactant in water or a lower alcohol, such as methanol, ethanol, isopropyl alcohol, etc. or covered with a solution using a knife.

(vi) Coating the surface

The dried microporous membrane may be covered with a porous polypropylene, porous fluorinated resin, such as polyvinylidene fluoride or polytetrafluoroethylene, porous polyimide; a porous polyster etc, to improve properties melting when used as separatorchar. Polypropylene for the coating layer preferably has a Mw 5000-500000 and solubility of 0.5 g or more in 100 g of toluene at 25°C. the polypropylene is more preferable with the fraction of racemic dyads from 0.12 to 0.88 to. In racemic dyad two related link monomer are enantiomers. The surface coating can be formed, for example, by coating a microporous membrane, a mixed solution containing the above-mentioned coating resin and a suitable solvent, removing a suitable solvent to increase the concentration of the resin, thus forming a structure in which the phase resin is separated from the phase of a suitable solvent, and removing the remaining suitable solvent.

(b) the Second way to obtain

The second method includes receiving stage (1) receipt of the above resin solutions a and b so that the concentration of the solution of resin And higher than that of the resin solution, (2) extrusion of the resin solutions a and b through separate dies, (3) cooling the obtained extrudates to obtain a gel-like sheets a and b, (4) removing membranebased solvent from the gel-like sheets a and b, (5) drying the resulting microporous polyethylene membranes a and b and (6) their alternate lamination. Before stage (4) remove membranebased solvent can be carried out when the necessity is the stage of stretching the gel-like sheets a and b, shrinking, processing hot roller and processing of hot solvent. Next, after the stage of lamination (6)can be carried out stage re-stretching, heat treatment, treatment with a hot solvent, knitting, hydrophilization, surface coating, etc.

Among the above stages stage (1) may be the same as in the first method, step (2) may be the same as in the first method, except extrusion of the resin solutions a and b through separate dies, stage (3) can be the same as in the first method, except for the formation of gel-like sheets a and b, stage (4) can be the same as in the first method, except for the removal membranebased of separate solvent from the gel-like sheets a and b, and stage 5) may be the same as in the first method, except for separate drying microporous polyethylene membranes a and B. it Should be noted that at the stage of (5) temperature drying microporous membranes a and b is preferably equal to or lower than the temperature of the dispersion of crystals Tcdaand Tcdbrespectively. The temperature of drying is more preferably lower than the temperature of the dispersion of crystals Tcdaand Tcdbat 5°C or more.

Stage stretching, shrinking, processing hot roller and processing of hot solvent before the study is th (4) can be the same, in the first method, except that they are conducted with a gel-like sheets a or C. However, when the gel-like sheet stretch to the stage (4), the stretching temperature is preferably in the range from the melting point TMandplus 10°C. or below, more preferably in the range of temperature dispersion of crystals Tcdaor higher, and to a temperature below the melting point TMand. When stretching the gel-like sheet In the stretching temperature is preferably in the range from the melting point TMbplus 10°C. or below, more preferably in the range of temperature dispersion of crystals Tcdbor higher, and to a temperature below the melting point TMb.

If shrinking the gel-like sheet And is held up to the stage (4), the temperature of the heat shrinkage is preferably in the range from the melting point TMandplus 10°C. or below, more preferably in the range of temperature dispersion of crystals Tcdaup to the melting point TMand. When shrinking the gel-like sheet temperature of heat shrinkage is preferably in the range from the melting point TMbplus 10°C. or below, more preferably in the range of temperature dispersion of crystals Tcdbup to the melting point TMb.

When processing hot roller gel-like sheet And to the stage (4 roll temperature is preferably in the range of temperature dispersion of crystals Tcd aplus 10°C or above to a temperature below the melting point TMand. When processing the gel-like sheet In the temperature of the roll preferably is in the range of temperature dispersion of crystals Tcdbplus 10°C or above to a temperature below the melting point TMb.

When processing hot solvent gel-like sheet And to the stage (4) the temperature of the hot solvent is preferably in the range of temperature dispersion of crystals Tcdaup to the melting point TMandplus 10°C. When processing the gel-like sheet In the temperature of the hot solvent is preferably in the range of temperature dispersion of crystals Tcdbup to the melting point TMbplus 10°C.

Stage (6) alternately laminating the microporous polyethylene membranes a and b will be described next. Although not especially critical, the method of lamination is preferably thermal lamination. The method of thermal lamination includes heat welding, pulse welding, ultrasonic lamination, etc., the method of heat welding is preferred. The method of thermal welding preferably uses a hot roll. In the way of a hot roll, the first and second microporous polyethylene membrane, which is overlapped, is subjected to the heat treatment of the coy welding by passing through a pair of heated rolls or between the heated roller and the plate. The temperature and pressure of thermal welding are not particularly critical, so far microporous polyethylene membranes are sufficiently related, and if only the resulting multi-layer microporous membrane will not have bad properties. The temperature of thermal welding is, for example, 90-135°C, preferably 90-115°C. thermal Pressure welding is preferably 0.01 to 50 MPa.

Stage re-stretching, heat treatment, treatment with a hot solvent, knitting, hydrophilization and coating surface after stage (6) can be the same as in the first method.

[3] Structure and properties of microporous polyethylene membrane

Microporous polyethylene membrane obtained by the method of the present invention, have a gradient structure in which the microporous layer formed by the solution of resin, has a larger average pore size than the pore diameter of the microporous layer formed by the resin solution And, consequently, the average diameter of the pores varies in thickness. The average pore diameter of the microporous layer more preferably 1.1 times or more, than the pore diameter of the microporous layer A.

Microporous polyethylene membrane obtained by the method of the present invention includes a microporous layer, which undergoes large deformation under compression and has come Bolshoe the change in the permeability, and the microporous layer a, which undergoes a small deformation under compression. Accordingly, when using a microporous polyethylene membrane as a separator of the battery microporous layer is changing with the expansion and shrinkage of the electrodes while maintaining the permeability, and the microporous layer And prevents a short circuit between the electrodes.

Although microporous polyethylene membrane usually has a laminar structure, it can be essentially a single-layer membrane, in which the microporous layers a and b merge at the boundary, provided that the average diameter of the pores varies in thickness. The number of layers in the microporous polyethylene membrane is not particularly critical. The location of the microporous layer and the microporous layer is not particularly critical, while the layers a and b alternate. In the case of three-layer microporous membrane, for example, the arrangement of the layers can be a/b/a or b/A/C.

The ratio of the thickness of the microporous layer And the microporous layer is not particularly critical, but may be appropriately selected depending on applications of microporous membranes. By adjusting the ratio of the thickness of the microporous layers a and b, it is possible to control the balance between compressive strength and absorption capacity compared to electrolytic RA is Toru. When used as a battery separator, the ratio of the cross sectional area of the microporous layer to the microporous layer, And is preferably 0.1 to 2.5. When this ratio is less than 0.1, the permeability of the microporous membrane undergoes significant change during compression at low absorptivity with respect to the electrolytic solution. When it is more than 2.5, the microporous membrane has low mechanical strength.

When used as a filter for liquids microporous layer And acts as a substrate and a microporous layer To act as a filter layer. Adjusting the attitude of the thickness of the microporous layers a and b, it is possible to control the balance between the filtering properties and permeability. The present invention provides filters with well-balanced filtering properties and permeability, even if they are made thinner than conventional filters.

The shape of the penetrating pores is not particularly critical. For example, two-layer microporous membrane layer structure a/b may have a narrowing of the pores with large holes on one surface, and their sizes gradually decrease toward the opposite surface. Three-layer microporous membrane layer structure In/And/In, for example, may have a penetrating pores whose sizes postopen the decrease from both surfaces to the center of the membrane.

Microporous polyethylene membrane in accordance with the preferred implementation of the present invention has the following properties.

Porosity 25-80%

With porosity less than 25% of microporous polyethylene membrane does not have good air permeability. When the porosity exceeds 80%, the microporous polyethylene membrane used as a separator of the battery does not have sufficient strength, which leads to a high probability of a short circuit between the electrodes.

(b) an Air permeability of between 20 and 500 seconds/100 cm3(in terms of thickness 20 μm)

When the air permeability is in the range between 20 and 500 seconds/100 cm3, battery separators of the microporous polyethylene membranes have a high capacity and good cycle characteristics. When the air permeability exceeds 500 seconds/100 cm3, battery low capacity. On the other hand, when the air permeability is less than 20 seconds/100 cm3does not completely turn off when the temperature in the batteries.

(c) the Strength of the perforation 1000 mn/20 μm or more

With the strength in piercing less than 1000 mn/20 μm in batteries containing microporous polyethylene membrane as a separator, probably a short circuit between the electrode of the MIS. The strength of the perforation preferably 2000 mn/20 μm or more.

(d) tensile Strength 70000 kPa or more

With a tensile strength of 70,000 kPa or more and in the longitudinal direction (MD) and transverse direction (TD) is a low probability of rupture of the membrane, when used as a battery separator.

(e) Elongation to break of 100% or more

With the elongation to break of 100% or more in the longitudinal direction (MD) and transverse direction (TD), low probability of rupture of the membrane when used as a battery separator.

(f) the Coefficient of heat shrinkage of 30% or less

The coefficient of heat shrinkage of 30% or less in the longitudinal direction (MD) and transverse direction (TD) after aging at 105°C for 8 hours. When used as a battery separator, the coefficient of heat shrinkage is preferably 15% or less, more preferably 10% or less.

(g) the rate of change of thickness after compression under heating for 10% or more the rate of change of thickness under compression at a temperature of 90°C and a pressure of 2.2 MPa (22 kgf/cm2within 5 minutes is 10% or more relative to 100% of the original thickness. If the rate of change of the thickness is 10% or more, the battery separator made of a microporous membrane, may well be damp expansion ele is trudov. This rate of change of the thickness is preferably 12% or more.

(h) Air permeability after compression to 1000 seconds/100 cm3or less

Air permeability after compression (figure Gurley), measured after compression under heating in the above conditions is 1000 seconds/100 cm3or less. With the permeability of the air after compression to 1000 seconds/100 cm3or less, the separator is formed from a microporous membrane, provides battery high capacity and good cycle characteristics. Air permeability after compression is preferably 900 seconds/100 cm3or less.

(i) shut-off Temperature of 140°C or below

When the shut-off temperature exceeds 140°C, the separator of the lithium battery, formed by the microporous membrane has low ability to overheat shutdown.

(j) the melting Temperature of 160°C or higher

The temperature of the melt is preferably 165°C. or more.

[4] the Separator of the battery

Microporous polyethylene membrane obtained in the above manner, has excellent mechanical properties, resistance to heat shrinkage and thermal properties with a small change in air permeability when compacted, which is suitable for battery separators. In particular, mi is Reparata membrane, obtained by the second method, has excellent resistance to heat shrinkage. Although the thickness of the separator of the battery appropriately selected depending on types of batteries, it is preferably 5-50 μm, more preferably 10-35 μm.

[5] Battery

Microporous polyethylene membrane of the present invention can be preferably used as a separator for secondary batteries such as lithium secondary batteries, lithium polymer secondary batteries, Nickel-hydrogen, Nickel-cadmium, Nickel-zinc, silver-zinc batteries, etc., especially as a separator for lithium secondary batteries. As the next example will be described lithium secondary battery.

A lithium secondary battery includes a cathode and an anode separated by a separator, the separator contains an electrolytic solution (electrolyte). The electrode may be of any known structure that is not particularly critical. The structure of the electrode can be, for example, type coins, in which the disc-shaped cathode and the anode are opposite to each other, the layered type in which a flat cathode and the anode are alternately assembled in layers, a toroidal type coil of the cathode and anode, made in the form of tapes, etc.

The cathode typically comprises (a) a current collector and (b) CL is the first active cathode material, able to absorb and discharge lithium ions, which is formed on the current collector. Active cathode materials can be inorganic compounds such as transition metal oxides, composite oxides of lithium and transition metals (lithium composite oxides, sulfides of transition metals, etc. Transition metals can be V, Mn, Fe, Co, Ni, etc. Preferred examples of the lithium composite oxides are nicelt lithium, kobaltt lithium, manganate lithium laminar lithium composite oxides with the structure of α-NaFeO2and so the Anode comprises (a) a current collector and (b) a layer of anode active material formed on the current collector. The active anode material may be a carbon material such as natural graphite, artificial graphite, coke, gas, soot, etc.

Electrolytic solutions can be obtained by dissolving lithium salts in organic solvents. The lithium salts can be LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiCF3SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, Li2B10Cl10, LiN(C2F5SO2)2, LiPF4(CF3)2, LiPF3(C2F5)3, lower aliphatic carboxylates of lithium, LiAlCl4etc. lithium Salts can be used separately or in combination. The PR is adicheskii solvents can be organic solvents with high boiling point and a high dielectric constant, such as ethylene carbonate resulting, propylene carbonate, ethylmethylketone, γ-butyrolactone, and so on; organic solvents with a low boiling point and low viscosity, such as tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, dioxolane, dimethylcarbonate, diethylcarbamyl etc. These organic solvents may be used separately or in combination. Because organic solvents with high dielectric constant have a high viscosity, while solvents with low viscosity has a low dielectric constant, preferably using a mixture thereof.

When assembling the battery separator may be impregnated with the electrolytic solution so that the separator (microporous polyethylene membrane was permeable to ions. The impregnation can be carried out (and usually provoditsya) by immersing the microporous membrane in the electrolytic solution at room temperature. When assembling a cylindrical battery, for example, a sheet cathode, a separator made of a microporous membrane and a sheet electrode are formed in this order and the resulting laminate is rolled into the electrode Assembly of the toroidal type. The obtained electrode Assembly can be loaded into the battery case and to impregnate the above electrolytic solution. The cover of the battery acting as the end ka the ode, equipped with a safety valve, can be placed in the battery case and sealing gasket for receiving the battery.

The present invention will be described in more detail with reference to examples below without intention to limit the scope of the claims of the invention.

Example 1

The composition of the resins a and b, are presented in table 1, receive for producing a microporous polyethylene membrane.

(1) preparation of resin solution And

Mix dry 100 mass. parts of the polyethylene composition (D)containing 18 wt%. the ultrahigh-molecular weight polyethylene (UHMWPE) with srednevekovoi molecular weight Mw of 2.0×106and 82% of the mass. high density polyethylene (HDPE) with Mw of 3.5×105from 0.2 mass. parts tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane as an antioxidant. The measurement showed that the polyethylene composition comprising UHMWPE and HDPE has a melting point of 135°C and the temperature dispersion of crystals 100°C., Mw of 6.4×105and Mw/Mn21,0.

Mws UHMWPE, HDPE and PE composition measured by gel permeation chromatography (GPC) under the following conditions.

Apparatus: GPC-150C supplied by Waters Corporation,

Column: Shodex UT806M, supplied by Showa Denko K.K.,

The column temperature: 135°C

The solvent (mobile phase): o-dichlorobenzene,

The flow rate of solvent: 1.0 mlmin,

Concentration of sample: 0.1% mass. (dissolved at 135°C for 1 hour)

Injected quantity: 500 µl,

Detector: differential Refractometer, Waters supplied Corp., and

Calibration curve: the calibration curve of monodisperse standard polystyrene using a given coefficient.

40 mass. parts of the resulting mixture is loaded into a twin-screw extruder with intensive stirring with an inner diameter of 58 mm and a ratio of length to diameter L/D=42 and 60 of the masses. parts of liquid paraffin [35 cSt (40°C)] served in a twin-screw extruder via a side feeder. The melt mixing is carried out at 230°C and 250 rpm to obtain the first resin solution A.

(2) obtaining a solution of the resin In

The resin solution prepared In the same way as before except for the changes in the concentration of the polyethylene composition to 20% of the mass.

(3) the Formation of membrane

The resin solutions a and b are served from a separate twin-screw extruder to T-filiere for sandwich molding and ekstragiruyut through a T-die plate so that the solution In the solution a and the solution In the laminate with respect to the layer thicknesses In/And/In components 1/1/1. The extrudate is cooled by drawing cooling roller supported at 0°C, thus obtaining a three-layer gel-like sheet. Using frame RA is tainai machine three-layer gel-like sheet and simultaneously biaxial stretch at 117,5°C. thus, the stretching ratio is 5 times in the longitudinal direction (MD) and transverse direction (TD). Mounted on an aluminum frame of 20 cm×20 cm, stretched three-layer gel-like sheet is dipped in a wash tub with methylene chloride at 25°C. and washed with vibration of 100 rpm for 3 minutes to remove the liquid paraffin. The washed membrane was dried in air at room temperature and fix into the recliner machine for shrinking at 128°C for 10 minutes, resulting in a gain of microporous polyethylene membrane.

Example 2

Microporous polyethylene membrane receives the same way as in example 1, except that a three-layer gel-like sheet is washed and then stretch 1.4-fold in TD at 129°C and that the shrinking is carried out at 129°C.

Example 3

(1) preparation of resin solution And

The resin solution And with a concentration of 40 wt%. receive the same manner as in example 1 except for use of the PE composition (melting point 135°C, the temperature of the dispersion of crystals 100°C., Mw of 9.3×105and Mw/Mn24,5), containing 35% of the mass. UHMWPE and 65% of the mass. HDPE.

(2) obtaining a solution of the resin In

A solution of resin In a mass ratio of UHMWPE/HDPE 18/82 receive the same manner as in example 1 except that the concentration of PE composition is 15% of the mass.

(3) Forming IU the gap

The resin solutions a and b are served from a separate twin-screw extruder to T-filiere for sandwich molding and ekstragiruyut through a T-die plate so that the solution A, solution b and solution And laminated in this order with respect to the thickness of the layers a/b/A equal to 1/1/1. The extrudate is cooled by pulling a cooling roller supported at 0°C, thus obtaining a three-layer gel-like sheet. Using a recliner frame machine three-layer gel-like sheet and simultaneously biaxially stretched at 115°C. so that the stretching ratio is 5 times in the longitudinal direction (MD) and transverse direction (TD). Stretched three-layer gel-like sheet is washed and air dried as in example 1. The dried membrane stretch recliner in the car 1.4-fold in TD at 128,5°C and maintained at 128,5°C for 10 minutes to obtain a microporous polyethylene membrane. Example 4

Microporous polyethylene membrane receive the same manner as in example 3, except that the ratio of the thickness of the layer of solution a, solution b and solution And the extrudate is 2/1/2.

Example 5

(1) preparation of resin solution And

The resin solution And with a concentration of 40 wt%. receive the same manner as in example 1 except for use of the PE composition (melting point 135°C, the temperature of the dispersion of crystals 100°C., Mw of 4.3×10 and Mw/Mn16,0)containing 5% wt. UHMWPE and 95% of the mass. HDPE.

(2) obtaining a solution of the resin In

The resin solution In get as well as the above resin solution A, except that the concentration of PE of the composition is 20% of the mass.

(3) the Formation of membrane

The resin solutions a and b are served from a separate twin-screw extruder to T-filiere for sandwich molding and ekstragiruyut through a T-die plate so that the solution A, solution b and solution And laminated in this order with respect to the thickness of the layers a/b/A equal to 1/1/1. The resulting extrudate is cooled by pulling a cooling roller supported at 0°C, thus obtaining a three-layer gel-like sheet. Using a recliner frame machine three-layer gel-like sheet and simultaneously biaxial stretch at 117,5°C so that the stretching ratio is 5 times in the longitudinal direction (MD) and transverse direction (TD). Stretched three-layer gel-like sheet is washed and air dried as in example 1. The dried membrane stretch recliner in the car 1.4-fold in TD at 129°C and subjected to heat shrinkage at 129°C for 10 minutes to obtain a microporous polyethylene membrane.

Example 6

(1) preparation of resin solution And

The resin solution And with a concentration of 40 wt%. receive the same manner as in example 1, except COI is whether the composition, containing 5% wt. UHMWPE, 90% of the mass. HDPE and 5% of the mass. PP having Mw of 5.3×105RE composition of UHMWPE and HDPE has a melting point of 135°C, the temperature of the dispersion of crystals 100°C., Mw of 4.4×105and Mw/Mn 16,0.

(2) obtaining a solution of the resin In

The resin solution In get as well as the above resin solution A, except for changing the resin concentration to 20 wt. -%

(3) the Formation of membrane

Microporous polyethylene membrane receives the same way as in example 5 except for using the resulting resin solutions a and B.

Example 7

Microporous polyethylene membrane receives the same way as in example 6, except RHT with Mw of 3.8×104instead of PP.

Example 8

Microporous polyethylene membrane receives the same way as in example 3, except that simultaneously and biaxially stretched three-layer gel-like sheet is subjected to heat shrinkage at 122°C for 10 minutes and then washed, re-stretch and subjected to heat shrinkage at a temperature of 129.5°C.

Example 9

Microporous polyethylene membrane receives the same way as in example 3, except that simultaneously and biaxially stretched three-layer gel-like sheet is dipped into a bath of liquid paraffin, supported at 120°C for 3 seconds and then washed and re-stretch and subjected to heat shrinkage at 130 is C.

Example 10

(1) Obtaining a microporous polyethylene membrane And

The resin solution And the concentration of the resin 40% of the mass. get in the same way as in example 1 except for use of the PE composition (melting point 135°C, the temperature of the dispersion of crystals 100°C., Mw of 4.3×105and Mw/Mn 16,0)containing 5% wt. UHMWPE and 95% of the mass. HDPE. The resin solution And ekstragiruyut from a T-die attached to the upper output co-rotating twin screw extruder, and cooled at pulling the cooling roller supported at 0°C, thus forming a gel-like sheet A. Gel-like sheet simultaneously and biaxially stretched 5 times in the longitudinal direction (MD) and transverse direction (TD) at 116°C frame recliner machine and then washed and air dried as in example 1 to obtain a microporous polyethylene membrane A.

(2) Obtaining a microporous polyethylene membrane

The resin solution In get as well as the above resin solution And, except PE composition (melting point 135°C, the temperature of the dispersion of crystals 100°C., Mw of 6.4×105and Mw/Mn 21,0)containing 18 wt%. UHMWPE and 82% of the mass. HDPE, and the fact that the concentration of the resin is 20% of the mass. Microporous polyethylene membrane To receive the same as the above-mentioned microporous polyethylene membrane And, except for using the resin solution In

(3) Lamination and shrinking

Microporous polyethylene membranes a and b laminated by passing through a pair of rolls at a temperature of 110°C and a pressure of 0.05 MPa. The resulting laminate is subjected to heat shrinkage using the method on the frame at a temperature of 126°C for microporous polyethylene membrane, in which the ratio of the thickness of the membrane And the membrane is 1/1.

Example 11

(1) preparation of resin solution And

The resin solution And get the same as in example 1, except that used RE composition (melting point 135°C, the temperature of the dispersion of crystals 100°C., Mw of 8.2×105and Mw/Mn 23,5)containing 30% of the mass. UHMWPE and 70% of the mass. HDPE, and the fact that the concentration of the resin is 30% of the mass.

(2) obtaining a solution of the resin In

A solution of resin In a mass ratio of UHMWPE/HDPE equal 18/82 receive the same as in example 1 except that the resin concentration is 15% of the mass.

(3) the Formation of membrane

The resin solutions a and b are served from a separate twin-screw extruder T-die plate for two-layer molding and ekstragiruyut through a T-die plate in the form of a laminate of solution a and solution b with respect to the thickness of the layers a/b equal to 1/1. The extrudate is cooled by pulling a cooling roller supported at 0°C, thus obtaining a two-layer gel-like sheet. Using a frame to grow the forming machine double layer gel-like sheet simultaneously and biaxially stretched 5 times in the longitudinal direction (MD) and transverse direction (TD) at 119,2°C. Stretched two-layer gel-like sheet is washed and air dried as in example 1. The dried membrane stretch recliner in the car 1.4-fold in TD at 110°C and subjected to heat shrinkage at 110°C for 10 minutes to obtain a microporous polyethylene membrane.

Example 12

The resin solutions a and b receive the same as in example 11. The resin solutions a and b ekstragiruyut separate from the T-dies, each attached to the upper output of each co-rotating twin screw extruder, and cooled at pulling the cooling roller supported at 0°C, thus forming a gel-like sheets a and B. the Gel-like sheets a and b simultaneously and biaxial using frame recliner machine stretch 5 times in the longitudinal direction (MD) and transverse direction (TD) at 119,2°C. the Stretched gel-like sheet is washed and air dried as in example 1 to obtain a microporous polyethylene membranes a and B. Microporous membrane and laminated by passing through a pair of rolls heated to a temperature of 110°C., at a pressure of 0.05 MPa. The resulting laminate stretch 1.4-fold in TD at a temperature of 110°C on the frame, is subjected to heat shrinkage at a temperature of 120°C for 10 minutes to obtain a microporous polyethylene membrane with respect to the thickness of the layers a/b equal to 1/1.

Example 13

The resin solution And with respect to the ACC UHMWPE/HDPE 5/95 get the same as in example 10 except for changing the resin concentration to 30% of the mass. A solution of resin In a mass ratio of UHMWPE/HDPE 18/82 get the same way as in example 10. The resin solutions a and b are served from a separate twin-screw extruder T-die plate for two-layer molding and ekstragiruyut through a T-die plate so that the solution and solution In the laminate with respect to the thickness of the layers a/b equal to 1/1. The resulting extrudate is cooled by pulling a cooling roller supported at 90°C, thus forming a two-layer gel-like sheet. Double-layer gel-like sheet is washed and air dried as in example 1, and subjected to heat shrinkage at 125°C for 10 minutes to obtain a microporous polyethylene membrane.

Example 14

The resin solutions a and b receive the same as in example 13. The resin solution And ekstragiruyut from a T-die attached to the upper output co-rotating twin screw extruder, and cooled at pulling the cooling roller supported at 90°C, thus forming a gel-like sheet a resin Solution In ekstragiruyut from a T-die attached to the upper conclusion of another co-rotating twin screw extruder, and cooled at pulling the cooling roller supported at 60°C, thus forming a gel-like sheet C. the Gel-like sheets a and b are washed and air dried as in example 1 to obtain m croporate polyethylene membranes a and B. Microporous polyethylene membranes a and b laminated by passing through a pair of rolls at a temperature of 110°C and a pressure of 0.05 MPa and subjected to heat shrinkage at 128°C for 10 minutes to obtain a microporous polyethylene membrane with respect to the thickness of the layers a/b equal to 1/1.

Comparative example 1

The resin solution get the same way as in example 1 except for use of the PE composition (melting point 135°C, the temperature of the dispersion of crystals 100°C., Mw of 6.8×105and Mw/Mn 20,0). containing 20% of the mass. UHMWPE and 80% of the mass. HDPE, and the fact that the concentration of the resin is 30% of the mass. The resin solution ekstragiruyut from a T-die attached to the upper output co-rotating twin screw extruder, and cooled at pulling the cooling roller supported at 0°C, thus forming a gel-like sheet. The gel-like sheet simultaneously and biaxially stretched 5 times in the longitudinal direction (MD) and transverse direction (TD) at 115°C frame recliner machine. Stretched gel-like sheet is washed and air dried as in example 1. Attached to the chassis by a gel-like sheet is subjected to heat shrinkage at 125°C for 10 minutes to obtain a microporous polyethylene membrane.

Comparative example 2

Two resin solution get the same way as in example 1, except the concentration of resin 30% of the mass. and 28% of the mass. the respectively. Microporous polyethylene membrane receives the same way as in example 1, except that use of the above solutions of the resin that the simultaneous biaxial stretching is carried out at 115°C, which is a three-layer gel-like sheet is washed and then stretch 1.4-fold in TD at 124°C, and the temperature at which heat shrinkage is 124°C.

Footnote: (1) Mw represents srednevekovoy molecular weight.

(2) Mw/Mn is the molecular mass distribution.

(3) the Concentration of the compositions of the resin in the resin solutions a and b, respectively.

(4) the resin Concentration in the resin solution And the concentration of the resin in the resin solution Century.

(5) And represents the solution of the resins a and b is a solution of the resin Century

(6) Temperature (°C)/stretching ratio (number of times) in MD and TD, where MD represents a longitudinal direction, and TD is the transverse direction.

(7) Shrinking the gel-like sheet.

(8) And represents the microporous membrane and the microporous membrane Century

(9) LP is liquid paraffin.

Properties of microporous polyethylene membranes obtained in examples 1-14 and comparative examples 1 and 2, determine the following methods. The results are presented in table 2.

(1) average the I thickness (µm)

The thickness of the microporous polyethylene membrane was measured with 5 mm spacing of 30 cm in width contact thickness gauge, and the resulting average thickness.

(2) Air permeability (sec/100 cm3/20 µm)

Air permeability P1microporous polyethylene membrane with a thickness of T1measured in accordance with JIS R and count on an air permeability P2at a thickness of 20 μm by the formula R2=(P1×20)/T1.

(3) Porosity (%)

Porosity measured mass method.

(4) the Strength of the perforation (mn/20 μm)

The maximum load measured when the microporous polyethylene membrane with a thickness of T1pierce with a needle of 1 mm in diameter with a spherical end surface (radius R of curvature of 0.5 mm) at a speed of 2 mm per second. The measured maximum load L1count on the maximum load of L2at a thickness of 20 μm by the formula L2=(L1×20)/T1that is the strength of the piercing.

(5) Strength and elongation to break

They are measured using rectangular specimens 10 mm in width in accordance with ASTM D882.

(6) the Degree of heat shrinkage (%)

The degree of heat shrinkage of microporous polyethylene membranes after incubation at 105°C for 8 hours was measured three times and in the longitudinal direction (MD) and transverse is UPRAVLENIE (TD) and average.

(8) shut-off Temperature

Using thermomechanical analyzer (TMA/SS6000, supplied by Seiko Instruments, Inc), the samples of 10 mm (TD)×3 mm (MD)stretching along the length of the load of 2 g, is heated at a speed of 5°C./minute from room temperature. The temperature at the inflection point observed near the melting point, is regarded as a shut-off temperature.

(8) melting Temperature (°C)

Using the above thermomechanical analyzer tested samples of 10 mm (TD)×3 mm (MD)stretching along the length of the load of 2 g, is heated at a speed of 5°C./minute from room temperature to measure the temperature at which the samples are broken due to melting.

(9) the Degree of change in thickness when compressed with heat

A sample of the microporous membrane is placed between two flat plates of a press, each of which has a very smooth surface, and squeeze press at a pressure of 2.2 MPa (22 kgf/cm2) and 90°C for 5 minutes to determine the average thickness of the above method. The rate of change of the thickness calculated by taking the thickness before compression for 100%.

(10) Air permeability after compression (sec/100 cm3)

The air permeability of the microporous polyethylene membrane, subjected to compression when heated under the above conditions, measured in accordance with JIS R and is considered as "air permeability after compression under heating".

(11) the Average diameter of pores

Choose randomly 50 then each microporous layer And, in the transmission electron micrograph (photograph) of the cross-section of a microporous membrane, measure their dimensions and average to determine the average diameter of pores in each layer.

From table 2 it is clear that as each microporous polyethylene membrane of examples 1-14, obtained in accordance with the present invention, has a gradient structure in which the average diameter of the pores varies in thickness, it has excellent resistance to compression (deformation during compression and permeability after compression), permeability, mechanical properties, resistance to heat shrinkage and thermal properties.

On the other hand, one solution of the resin used for the formation of gel-like sheet in comparative example 1, and two resin solution used for forming a three-layer gel-like sheet in comparative example 2 have a difference in concentration of the resin is less than 5% of the mass. Accordingly, any of the membranes of comparative examples 1 and 2 have higher air permeability after compression and have more poor resistance to compression than the membranes in examples 1-14.

Positive E. the effect of the invention

In accordance with the present invention the microporous polyethylene membrane with an average pore diameter of varying thickness, which has a well-balanced permeability, mechanical properties, resistance to heat shrinkage, compressive strength, absorption ability with respect to the electrolytic solution, the properties off and melt, can be made with simple control of the average diameter of pores in thickness. It is easy to control the ratio of the coarse-grained layer structure with a large average pore diameter of the layer of dense patterns with a smaller average pore size and pore size in each layer. The use of microporous polyethylene membrane manufactured by the method in accordance with the present invention as a separator of the battery gives excellent battery capacity, cycle characteristics, properties, discharge, temperature resistance, resistance to compression and performance.

1. The method of producing microporous polyethylene membrane with an average pore diameter of changing the thickness of the membrane, comprising a stage of mixing of the melt, at least, a polyethylene resin containing an ultrahigh-molecular weight polyethylene with srednevekovoi molecular weight of 1×106up to 5×106and high-density polyethylene with an average the weight molecular weight of 1×10 4to less than 5×105and membranebased solvent to obtain a solution of the polyethylene resin And the concentration of the resin 30-40 wt.%, and solution of the polyethylene resin concentration of the resin 15-20 wt.%, the concentration of the resin in a solution of polyethylene resin And higher than in the solution of the polyethylene resin and the difference in concentration of the resin between the solutions of polyethylene resins a and b is from 10 to 25 wt.% or more; simultaneous extrusion of solutions of polyethylene resins a and b through the die plate; cooling the resulting laminate extrudate to obtain a gel-like sheet; and removing membranebased solvent from the gel-like sheet.

2. The method of producing microporous polyethylene membrane with an average pore diameter of changing the thickness of the membrane, comprising a stage of mixing of the melt, at least, a polyethylene resin containing an ultrahigh-molecular weight polyethylene with srednevekovoi molecular weight of 1×106up to 5×106and high-density polyethylene with srednevekovoi molecular weight of 1×104to less than 5×105and membranebased solvent to obtain a solution of the polyethylene resin And the concentration of the resin 30-40 wt.%, and solution of the polyethylene resin concentration of the resin 15-20 wt.%, the concentration of the resin in a solution of the polyethylene the OIC resin As above, than in the solution of the polyethylene resin and the difference in concentration of the resin between the solutions of polyethylene resins a and b is 10-25 wt.%, or more; extrusion of solutions of polyethylene resins a and b through a separate die; cooling the obtained extrudates to obtain a gel-like sheets a and b; delete membranebased solvent from the gel-like sheets a and b for the formation of microporous polyethylene membranes a and b; and alternately laminating the microporous polyethylene membranes a and B.

3. The method of producing microporous polyethylene membrane according to claim 1 or 2, wherein the polyethylene resin is a composition comprising a polyethylene composition, and a heat resistant resin with a melting point or glass transition temperature of 150°C or higher.

4. The method of producing microporous polyethylene membrane according to claim 3, in which the heat-resistant resin is a polypropylene terephthalate or polybutylene.

5. The battery separator formed from a microporous polyethylene membrane obtained in accordance with the method according to one of claims 1 to 4.



 

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17 cl, 8 dwg, 3 tbl, 13 ex.

FIELD: chemistry.

SUBSTANCE: invention refers to production of proton-conducting membranes based on ionogenic hydrophilic copolymers applied in membrane fuel elements. According to invention polymer composition for proton-conducting membranes designed as interpenetrating polymer networks composed of N-vynilpyrrolidone ionogenic copolymer network, acrylonitrile, 2-acrylamide-2-methyl-1-propanesulphacid and cross-linking monomer (ethyleneglycoldimethacrylate or methylenebisacrylamide) at mass monomers relation (34.5-46.5):(34.5-46.5):(16.5-20.0):(0.5-2.0) and N-vynilpyrrolidone ionogenic copolymer network, acrylonitrile and ethyleneglycoldimethacrylate at mass monomers relation (19.5-79.5):(19.5-79.5):(1.0-2.0). Mass copolymer relation is within the range 1.3-6.76. Polymer composition production includes sequential stages: synthesis of cross-linked ionogenic copolymer by means of radical copolymerization of specified monomers in divided closed polymer mold; saturation of crossed-linked ionogenic copolymer with monomers forming non-ionogenic copolymer network, radical copolymerization of monomers and formation of interpenetrating polymer networks.

EFFECT: production of polymer material for membranes high-conductivity and mechanical strength.

12 cl, 2 tbl, 16 ex

FIELD: process engineering.

SUBSTANCE: invention relates to multilayer microporous polyethylene membrane and storage battery made thereof. Proposed membrane has at least two microporous layers. One layer (a) of polyethylene resin A contains high-density polyethylene A with 0.2 and more end vinyl groups per 10 000 carbon atoms defined by IR-spectroscopy. Second microporous layer (b) of polyethylene resin B contains high-density polyethylene A with smaller than 0.2 end vinyl groups per 10 000 carbon atoms defined by IR-spectroscopy. Said membrane is produced by two methods. First method comprises simultaneous extrusion of solutions of polyethylene resins A and B through spinneret, cooling of extrudate, removing of solvent and laminating. Second method comprises extrusion of said solutions through different spinnerets. Said membrane is used to produce storage battery separator.

EFFECT: well-balanced characteristics of melting and cutting-off, good forming property of film and separator and anti-oxidation properties.

4 cl, 1 tbl, 3 ex

FIELD: electricity.

SUBSTANCE: according to the invention, an organic/inorganic composite divider contains a porous substrate with pores; and a porous active layer containing a mixture of inorganic particles and a binding polymer which covers at least one surface of said porous substrate. The porous active layer is characterised by a thickness-through composition morphology heterogeneity where the quantitative relation 'binding polymer/inorganic particles' on the surface layer is higher than the quantitative relation 'binding polymer/inorganic particles' inside the surface layer.

EFFECT: improved performance of an accumulator.

28 cl, 5 dwg, 1 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: present invention refers to the field of organic-inorganic composite porous separator and battery thereof. According to the invention the separator includes (a) porous support; and (b) organic-inorganic composite layer formed by the coating of at least one area selected from the group consisting of the support surface and part of the support pores with the mixture of inorganic porous particles and binding polymer. The inorganic porous particles having great number of macropores with diametre 50 nm or more form thus the porous structure. In addition the present invention provides the method of fabrication of organic-inorganic porous separator and battery thereof. Since due to numerous pores existing in the inorganic particle itself the additional paths for lithium ions are created the decrease of battery efficiency can be minimised and due to mass loss the gravimetric energy density can be increased.

EFFECT: increase of gravimetric energy density.

17 cl, 10 dwg, 2 tbl, 11 ex

Accumulator battery // 2360333

FIELD: chemistry; electricity.

SUBSTANCE: invention relates to chemical source of electric energy and can be applied in designing and producing nickel cadmium battery with alkaline electrolyte. According to the invention nickel cadmium battery contains a metal container in which accumulators joined between each other with buses are placed. The accumulators consists of a vessel with multilayered separators separated by positive nickel oxide electrodes, negative cadmium electrodes, note that coarse porous separators are applied on positive and negative electrodes and fine porous separator is placed between them. The separators have particular characteristic ratio.

EFFECT: improvement of gas withdrawal from accumulators during charge, extended work life, increase of reliability and security of service within continuous application of accumulator batteries by aggravating formation of cadmium bridges.

3 dwg

FIELD: electricity.

SUBSTANCE: invention is attributed to electric engineering, in particular to method of porous material saturation and can be used in manufacturing chemical current sources. Saturation method includes material saturation with auxiliary liquid which is insoluble in treating liquid and has lower boiling temperature than that of treating liquid, and its subsequent immersion into treating liquid at higher temperature than auxiliary liquid boiling temperature. As a result residing in pores auxiliary liquid evaporates and its vapors only remain in material pores. Afterwards the material is immersed into treating liquid at substantially lower temperature than auxiliary liquid condensation temperature. In this process auxiliary liquid condensation takes place in material pores while vacuum is created in them and pores are filled with treating liquid.

EFFECT: increase in efficiency of saturation process, increase of pore bridging degree with simultaneous technology simplification.

1 dwg, 1 tbl

Lead accumulator // 2354014

FIELD: chemistry.

SUBSTANCE: lead accumulator containing unit of negative electrodes and unit of positive electrodes separated by separators, which on sides facing positive electrodes have vertical ribs, and which are put into reservoir (monoblock unit) filled with electrolyte, has additionally installed between vertical ribs separators in form of volumetric three-layer frame from randomly interlaced lavsan fibres of diameter 0.2 mm and cell size between them not less than 2 mm.

EFFECT: prevention of melting and slumping of active mass of positive electrodes and increase of their service time.

3 dwg

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and may be used for manufacturing lead-acid batteries. Catalytic gas recombination device contains gas-proofed housing where porous container with catalyst is located. The housing is inside refrigerator where cooling fluid runs through. The cross section of inlet channel is more than the cross section of the outlet channel. The inlet channel cross section ratio to the outlet channel cross section is 1.3:1.0. It creates stable pressure in the channel and high speed of cooling fluid running.

EFFECT: increasing effectiveness of hydrogen and oxygen recombination into water and its return to battery when charged with high currents.

1 dwg, 1 tbl

FIELD: electricity.

SUBSTANCE: invention is attributed to alkaline accumulators, specifically to zinc-nickel accumulators. In this invention zinc-nickel accumulator comprises casing, alkaline ionogen solution, positive and negative electrodes separated by multilayer separator and porous metal inserts located in multilayer separator between positive and negative electrodes. In this structure the said metal inserts are electrically connected among themselves or made as single zigzag tape the zigs of which are located in multilayer separator between positive and negative electrodes. Edges of separate inserts or edges of single tape zigs can protrude out of separator for 1÷1.5 mm. Capron separator is used at positive electrodes and separator made of nonwoven polypropylene and alkali-proof paper is used at negative electrodes. The insert can be made of nickel foil 50÷60 micron in thickness and with porosity of 40÷50%. Zincate ionogen obtained from reaction of 50 g of ZnO with 1 l "КОН" with specific density of 1.3 g/cm3 is taken as electrolyte.

EFFECT: improvement of resource and electric characteristics.

6 cl, 1 ex

FIELD: electrical engineering; electrochemical power supplies.

SUBSTANCE: proposed electrochemical cell has two types of separators of different destruction energy and electrode assembly of several electrode layers; most external electrode layer of assembly has cathode non-covered with active material, anode non-covered with active material, and separator (second separator) disposed between these cathode and anode and characterized in relatively low destruction energy compared with that of separators (second separator) in other electrode layers.

EFFECT: enhanced safety of device.

13 cl, 9 dwg, 2 ex

FIELD: modifying electrodialysis plant membranes.

SUBSTANCE: proposed method for modifying anion-exchange membrane MA-40 involves treatment of the latter by dipping it in room-temperature aqueous solution of following composition, g/l: potassium or ammonium persulfate, 50 - 70; sulfuric acid, 50 - 70. Membrane treated in this way is used in membrane electrolyzer designed for extracting hexavalent chromium compounds (ion chromate and bichromate) from wash water filling intercepting bath.

EFFECT: improved exchange properties of membrane.

1 cl

FIELD: chemistry.

SUBSTANCE: invention relates to a biodegradable thermoplastic composition used in making films and various hot-moulded articles in form of consumer packaging. The composition contains polyethylene, a copolymer of ethylene and vinylacetate, starch, nonionic surfactant and schungite.

EFFECT: composition has good rheological characteristics and is biodegradable under the effect of light, moisture and soil microflora.

2 tbl, 4 ex

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