Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/04—Physical treatment, e.g. heating, irradiating
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/44—Fibrous material
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/24—Polyesters
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
  • H01M50/406—Moulding; Embossing; Cutting
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/431—Inorganic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
  • H01M50/494—Tensile strength
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a base material for a lithium ion secondary battery separator that can be suitably used for a lithium ion secondary battery such as a lithium ion secondary battery or a lithium ion polymer secondary battery, and a method for producing a base material for a lithium ion secondary battery separator And a lithium ion secondary battery separator.
• a lithium ion secondary battery using an organic electrolyte has attracted attention.
• This lithium ion secondary battery has an energy density of about 3.7 V, which is about three times that of an alkaline secondary battery, which is a conventional secondary battery, and thus has a high energy density.
• a water-based electrolyte cannot be used, a non-aqueous electrolyte having sufficient oxidation-reduction resistance is used.
• non-aqueous electrolytes are flammable, there is a risk of ignition and the like, and careful attention is paid to safety in their use. There are several possible cases of exposure to fire and other hazards, but overcharging is particularly dangerous.
• the current non-aqueous secondary battery has a protection circuit broken when overcharged, and is equipped with a safety valve / PTC element and a lithium ion secondary battery with a thermal fuse function for the purpose of safely destroying the battery when overcharged.
• Devices such as a separator have been devised.
• the safety during overcharge is not guaranteed, and in fact, non-aqueous secondary battery ignition accidents Is still happening.
• a film-like porous film made of polyolefin such as polyethylene is often used, and when the temperature inside the battery is around 130 ° C., it melts and closes the micropores.
• a thermal fuse function shutdown function
• the polyolefin itself may melt and short-circuit, suggesting the possibility of thermal runaway Has been.
• a heat-resistant separator that does not melt and shrink even at temperatures close to 200 ° C. has been developed.
• thermoresistant separators there are non-woven fabrics composed of polyester fibers, and non-woven fabrics in which aramid fibers, which are heat-resistant fibers, are blended with polyester-based fibers. References 1-3).
• a lithium ion secondary battery separator is made by performing various composite treatments on a base material for a lithium ion secondary battery separator such as a nonwoven fabric or a woven fabric.
• a film-like porous film made of polyolefin is laminated on a nonwoven fabric lithium ion secondary battery separator base material composed of polyester fibers and combined, or a lithium ion secondary such as a nonwoven fabric or woven fabric.
• An object of the present invention is to provide a base material for a lithium ion secondary battery separator and a base material for a lithium ion secondary battery separator that are excellent in processability at the time of manufacture and excellent in strength, uniformity, and ease of handling in subsequent steps. It is providing the manufacturing method and the lithium ion secondary battery separator which uses this base material for lithium ion secondary battery separators.
• the present invention for solving the above problems (1) Polyethylene terephthalate fiber is contained, the average fiber diameter of the polyethylene terephthalate fiber is 9.0 ⁇ m or less, the specific X-ray diffraction intensity derived from the polyethylene terephthalate fiber is 300 cps / (g / m 2 ) or more, A base material for a lithium ion secondary battery separator, wherein the coefficient of variation in specific X-ray diffraction intensity is 12.0% or less; (2) The lithium ion secondary battery separator substrate according to (1), wherein the polyethylene terephthalate fiber has an average fiber diameter of 4.0 to 8.0 ⁇ m, (3) In a method for producing a base material for a lithium ion secondary battery separator, a base paper containing polyethylene terephthalate fiber is subjected to a heat calendar process with a heat calendar device composed of a resin roll and a heated metal roll.
• a method for producing a base material for a lithium ion secondary battery separator (4) The base material for a lithium ion secondary battery separator according to (3), wherein the base paper is subjected to thermal calendering in two or more stages (2 nips) so that both the front and back surfaces of the base paper are in contact with the heated metal roll.
• Production method (5) A base material for a lithium ion secondary battery separator produced by the method for producing a base material for a lithium ion secondary battery separator according to (3) or (4), (6) Lithium ion, characterized in that a coating layer containing inorganic particles is provided on the lithium ion secondary battery separator substrate according to any one of (1), (2), and (5). Secondary battery separator, It is about.
• the lithium ion secondary battery separator base material (1), (2) and (5) of the present invention becomes a lithium ion secondary battery separator (6) by providing a coating layer containing inorganic particles.
• the base material (1) for a lithium ion secondary battery separator of the present invention comprises polyethylene terephthalate fiber, the average fiber diameter of the polyethylene terephthalate fiber is 9.0 ⁇ m or less, and the specific X-ray diffraction derived from the polyethylene terephthalate fiber.
• the intensity is 300 cps / (g / m 2 ) or more, and the coefficient of variation of specific X-ray diffraction intensity is 12.0% or less.
• the base material for lithium ion secondary battery separator (1) of the present invention has good processability when providing a coating layer containing inorganic particles, compared to the conventional base material for lithium ion secondary battery separator, Excellent strength, uniformity, and handleability in subsequent processes.
• the base material (2) for lithium ion secondary battery separator of the present invention in which the average fiber diameter of polyethylene terephthalate fiber is 4.0 to 8.0 ⁇ m is obtained by adding inorganic particles to the base material for lithium ion secondary battery separator. Workability in providing the coating layer to be contained is better, and it is more excellent in strength, uniformity, and handleability in subsequent steps.
• a thermal calendar in which a base paper containing polyethylene terephthalate fibers is composed of a resin roll and a heated metal roll
• the base material for lithium ion secondary battery separators is manufactured by carrying out the heat
• the workability, strength, uniformity, and handleability in the subsequent process when providing the coating layer to be contained are further improved.
• the substrate (1) or (2) for a lithium ion secondary battery separator of the present invention is more efficiently produced by the method (3) or (4) for producing a substrate for a lithium ion secondary battery separator of the present invention. It becomes possible.
• base material for a lithium ion secondary battery separator of the present invention
• base material a method for producing a base material for a lithium ion secondary battery separator, and a lithium ion secondary battery separator
• the “separator” may be abbreviated in detail.
• the substrate of the present invention contains polyethylene terephthalate (PET) fibers, the average fiber diameter of the PET fibers of the entire substrate is 9.0 ⁇ m or less, and the specific X-ray diffraction intensity derived from PET fibers is 300 cps / ( g / m 2 ) or more, and the coefficient of variation in specific X-ray diffraction intensity is 12.0% or less.
• PET polyethylene terephthalate
• the average fiber diameter of the fibers in the present invention was measured according to the following procedure. 1) A micrograph of the surface of the substrate is taken at a magnification of 1000 times. 2) In the above picture, the fiber diameter is measured for PET fibers that intersect with the drawn line in the direction (width direction, CD) perpendicular to the flow direction (machine direction, MD) of the substrate. To do. 3) For the fibers to be measured, when the fibers intersect perpendicularly or obliquely with respect to the line, the fiber width in the direction perpendicular to the fiber axis is measured as the fiber diameter. 4) For a plurality of micrographs, the fiber diameters of at least 50 fibers were measured and averaged in the measurements of 1) to 3).
• the average fiber diameter of the PET fibers is measured for both surfaces of the base material, and the average value of the average fiber diameters of both surfaces is defined as “average fiber diameter”.
• the coating solution containing inorganic particles penetrates the substrate appropriately.
• the coating liquid penetrates into the base material, the binding force at the interface between the coating layer and the base material becomes strong, and the strength of the coating layer becomes strong.
• strength of a base material improves because a coating liquid osmose
• the average fiber diameter of the PET fibers used for the base material for the lithium ion secondary battery separator exceeds 9.0 ⁇ m, the density at which the fibers intersect in the nonwoven fabric is lowered, and the strength is hardly developed.
• the coating liquid easily penetrates in the thickness direction of the nonwoven fabric, and the coating liquid penetrates the opposite surface where the coating liquid is applied.
• the coating machine is soiled and the workability is deteriorated, and the penetrating coating liquid impairs the uniformity of the base material for the lithium ion secondary battery separator.
• the average fiber diameter of the PET fibers is 9.0 ⁇ m or less, more preferably in the range of 4.0 to 8.0 ⁇ m, and still more preferably in the range of 4.0 to 7.0 ⁇ m. It is a range.
• a value obtained by dividing an average value of measured values of X-ray diffraction intensity by basis weight is defined as “specific X-ray diffraction intensity”.
• the X-ray diffraction intensity derived from the crystal part of the PET fiber in the substrate can be determined by measuring with an X-ray diffractometer.
• the X-ray diffraction intensity derived from the PET fiber changes depending on the thermal history received in the manufacturing process. That is, the degree of crystallization changes.
• strength of a base material improves because X-ray diffraction intensity
• the specific X-ray diffraction intensity is 300 cps / (g / m 2 ) or more, more preferably 340 cps / (g / m 2 ) or more, and further preferably 380 cps / (g / m 2 ) or more. is there.
• the X-ray diffraction intensity is measured at five or more measurement points of the base material, and the average value of the diffraction intensity is obtained at the same time.
• a large variation coefficient means that the variation in crystallinity of PET fibers in the surface direction of the substrate is large.
• the coefficient of variation of the specific X-ray diffraction intensity of the base material is 12.0% or less, so that when used in practice, the base material has few irregularities and waves and is excellent in workability. I found out.
• the coefficient of variation is 12.0% or less, more preferably 9.0% or less, and still more preferably 3.0% or less.
• the manufacturing process in which the base material receives a thermal history includes a drying process when the base paper is manufactured by a wet papermaking method, a process of heat-bonding the fibers when the base paper is manufactured by a dry process, and a thermal calendar treatment of the base paper Etc.
• thermal calendering of the base paper is most effective for obtaining a substrate having a specific X-ray diffraction intensity derived from PET fibers of 300 cps / (g / m 2 ) or more and excellent strength.
• a metal roll is used as the heating roll.
• a metal roll and an elastic roll can be used.
• the heat calender device composed of a metal roll and a metal roll can press the heated metal roll against the front and back surfaces of the substrate, and has a relatively wide processing temperature range and processing linear pressure. It is possible to operate in the area.
• heat and a load are applied to the base material with a narrow nip width, so that distortion is likely to occur and defects such as wrinkles and cracks occur. There is a case.
• a heat calender device composed of a metal roll and an elastic roll
• heat and a load are applied to the base material with a wide nip width, so there is little distortion in the base material, which can cause defects such as wrinkles and cracks. Absent.
• the specific X-ray diffraction intensity derived from PET fiber is 300 cps / (g / m 2 ) or more and the coefficient of variation is 12 It is possible to efficiently provide a substrate that is 0.0% or less, excellent in strength, and excellent in uniformity.
• a roll having a Shore D hardness of 85 to 94 can be selected.
• the use of a roll having a Shore D hardness of 90 or more is desirable in terms of the durability of the roll and the strength and uniformity of the substrate.
• the specific X-ray diffraction intensity and the coefficient of variation of the specific X-ray diffraction intensity of the substrate can be adjusted by the linear pressure, processing temperature (temperature of the heated metal roll), and processing speed during the heat calendering process. it can.
• the treatment temperature is preferably 170 to 200 ° C, more preferably 180 to 200 ° C, and further preferably 185 to 200 ° C. If the treatment temperature during the thermal calendar treatment is low, the crystallization of the PET fiber does not proceed and sufficient strength may not be exhibited.
• the specific X-ray diffraction intensity may be decreased, or the coefficient of variation of the specific X-ray diffraction intensity may be increased. Moreover, it may melt excessively on the surface of the heating roll during the heat calendering process and induce defects.
• the variation coefficient of the specific X-ray diffraction intensity and the specific X-ray diffraction intensity of the base material can be adjusted also by the linear pressure during the heat calendar process.
• the linear pressure during the heat calendering process varies depending on the basis weight of the substrate, the processing speed, and the material of the calender roll, but is preferably 100 to 190 kN / m, more preferably 125 to 190 kN / m, More preferably, it is 150 to 175 kN / m. If the linear pressure during the heat calendering process is too low, the crystallization of the PET fiber does not proceed and sufficient strength may not be exhibited. If the linear pressure during the heat calendering process is too high, an excessively crushed portion is generated in a minute portion, and a crack defect tends to occur around the portion. In addition, the uniformity within the sheet may be impaired.
• the variation coefficient of the specific X-ray diffraction intensity and the specific X-ray diffraction intensity of the base material can be adjusted even at the processing speed of the thermal calendar process. If the processing speed at the time of the thermal calendar process is increased, the amount of heat per unit time applied from the thermal calendar to the base material may decrease, and as a result, the crystallization of the PET fibers in the base material may not easily proceed. In order to increase the processing speed during the thermal calendar process, the crystallization of the PET fiber can be promoted by increasing the processing temperature, increasing the calender linear pressure, and performing a multi-stage thermal calendar process.
• the specific X-ray diffraction intensity derived from the PET fiber is more efficient. Is 300 cps / (g / m 2 ) or more and the coefficient of variation is 12.0% or less, and it is possible to provide a lithium ion secondary battery separator substrate having excellent strength and uniformity.
• the crystallization of the polyethylene terephthalate fiber can be promoted uniformly in the thickness direction of the base material by performing a heat calender treatment so that both the front and back surfaces of the base material are in contact with the heated metal roll.
• a heat calender treatment so that both the front and back surfaces of the base material are in contact with the heated metal roll.
• a substrate that is more efficient, excellent in strength, and excellent in uniformity.
• a one-stage treatment (one nip) is performed with a heat calender device composed of a heated metal roll-heated metal roll.
• one of heated metal rolls-elastic rolls, etc. which is a heated metal roll, 2 so that the front and back surfaces of the substrate are in contact with the heated metal roll.
• fever calendar process more than a step process (2 nips) is mentioned.
• two or more steps (two nips) or more are performed so that the front and back surfaces of the base material are in contact with a heated metal roll.
• a method in which the thermal calendar treatment is performed is preferable. If necessary, a multi-stage thermal calendar process of three or more stages (three nips) or more may be performed.
• the base material of the present invention contains PET fibers as constituent fibers.
• PET fiber the main fiber which plays the role which forms the frame
• the fiber length of the main fiber is not particularly limited, but is preferably 1 to 12 mm, more preferably 3 to 10 mm, and further preferably 4 to 6 mm.
• the fiber length is less than 1 mm, it is difficult to form a three-dimensional network of fibers in the paper making process, and the peelability from the paper making wire may be deteriorated.
• the fiber length exceeds 12 mm, there is a concern that the uniformity of the substrate may be adversely affected due to the entanglement or twisting of the fibers.
• the cross-sectional shape of the main fiber is preferably circular, but fibers having a modified cross section such as T-type, Y-type, and triangle can also be contained.
• binder fibers examples include core-sheath fibers (core-shell type), parallel fibers (side-by-side type), composite fibers such as radially divided fibers, unstretched fibers, and the like. Since the composite fiber hardly forms a film, the mechanical strength can be improved while maintaining the space of the semipermeable membrane support. More specifically, a combination of a high-melting point polyester (core) and a low-melting point polyester (sheath), and unstretched fibers such as polyester. In the present invention, a combination of a high-melting point polyester (core) and a low-melting point polyester (sheath) and unstretched polyester fibers can be preferably used.
• the fiber diameter of the binder fiber is preferably different from that of the main fiber, but is not particularly limited. Because the fiber diameter is different from the main fiber, the binder fiber plays a role of forming a uniform three-dimensional network together with the main fiber and the thin fiber, in addition to the role of improving the mechanical strength of the semipermeable membrane support, In the Yankee dryer and hot air drying, the smoothness of the substrate can be improved in the step of raising the temperature to the softening temperature or melting temperature of the binder fiber.
• the fiber length of the binder fiber is not particularly limited, but when the fiber length exceeds 20 mm, the formation tends to deteriorate.
• the cross-sectional shape of the binder fiber can also include a fiber having a circular shape and a modified cross-section such as a T shape, a Y shape, or a triangle.
• the content ratio of the main fiber and the binder fiber of the present invention is preferably 90:10 to 10:90 on a mass basis, more preferably 85:15 to 15:85, and 70:30 to 30:70. More preferably.
• the content ratio of the main fiber is less than 10% by mass, the microporosity of the substrate may be impaired.
• the content ratio of the main fiber exceeds 90% by mass, the mechanical strength of the base material may be lowered and may be easily broken.
• the base material of the present invention can be blended with fibers other than PET fibers as long as the quality and productivity are not impaired.
• fibers other than PET fibers examples thereof include polyolefin-based, polyamide-based, polyacrylic-based, vinylon-based, vinylidene-based, polyvinyl chloride-based, polyester-based fibers other than PET, benzoate-based, polyclar-based fibers, phenol-based fibers, and the like.
• Semi-synthetic fibers such as acetate, triacetate, promix, and regenerated fibers such as rayon, cupra, and lyocell fiber may be contained within a range that does not impair the performance.
• the content ratio of PET fibers and fibers other than PET fibers is preferably 100: 0 to 70:30, more preferably 100: 0 to 80:20, more preferably 100: 0 to 90:10 on a mass basis. More preferably.
• Examples of the method for producing the base paper relating to the substrate of the present invention include a dry method such as a card method and an air lay method, a wet method such as a paper making method, a spunbond method, and a melt blow method.
• a base paper obtained by a wet method is preferable because it can provide a more homogeneous and dense base material as compared with other production methods.
• the main fibers and binder fibers are uniformly dispersed in water, and then passed through processes such as screen (removal of foreign matters, lumps, etc.), and the final fiber concentration is 0.01 to 0.50 mass%.
• the slurry prepared in (1) is made up with a paper machine to obtain a wet paper.
• chemicals such as dispersants, antifoaming agents, hydrophilic agents, antistatic agents, polymer thickeners, mold release agents, antibacterial agents, bactericides, etc. may be added during the process. is there.
• a paper net such as a long net, a circular net, or an inclined wire
• These papermaking nets can be used alone, or a combination papermaking machine in which two or more same or different types of papermaking nets are installed online may be used.
• the base paper has a multilayer structure of two or more layers
• a multi-layer method using a paper making machine having a plurality of headboxes on a single paper mesh, a method of laminating wet paper made by each paper mesh, Any one of a method of making another structure and a method of casting a slurry in which fibers are dispersed on the one sheet after forming one sheet may be used.
• the base paper is obtained by drying the wet paper produced by the paper machine with a Yankee dryer, air dryer, cylinder dryer, suction drum dryer, infrared dryer or the like.
• a hot roll such as a Yankee dryer and dried by heat and pressure to improve the smoothness of the contacted surface.
• Hot-pressure drying means that the wet paper is pressed against the heat roll with a touch roll or the like and dried.
• the surface temperature of the hot roll is preferably 100 to 180 ° C, more preferably 100 to 160 ° C, and still more preferably 110 to 160 ° C.
• the pressure is preferably 5 to 100 kN / m, more preferably 10 to 80 kN / m.
• the basis weight of the base material of the present invention is not particularly limited, but is preferably 5.0 ⁇ 30.0g / m 2, more preferably from 10.0 ⁇ 20.0g / m 2.
• it is less than 5.0 g / m 2 , paper breakage tends to occur in the paper making process, and sufficient tensile strength may not be obtained.
• it exceeds 30.0 g / m ⁇ 2 > when carrying out the heat calendar process of a base paper, it is necessary to provide a great amount of heat to a base paper, and productivity may fall.
• the density of the base material of the present invention is preferably 0.45 to 0.75 g / cm 3 , more preferably 0.50 to 0.65 g / cm 3 .
• the density of the substrate is less than 0.45 g / cm 3, the bonding area between the PET fibers is not sufficient, and sufficient strength of the entire substrate may not be expressed.
• it exceeds 0.75 g / cm 3 the PET fibers are excessively fused with each other to form a film, which may impair uniformity.
• the lithium ion secondary battery separator of the present invention is obtained by providing a coating layer containing inorganic particles on the base material for the lithium ion secondary battery separator of the present invention.
• the coating layer provided on the substrate contains inorganic particles, and optionally contains a binder resin.
• inorganic particles alumina such as ⁇ -alumina, ⁇ -alumina and ⁇ -alumina; hydrated alumina such as boehmite and pseudoboehmite; magnesium oxide; calcium oxide; silica and the like can be used.
• ⁇ -alumina or alumina hydrate is preferably used because of its high stability to the electrolyte used in the lithium ion secondary battery.
• the binder resin various synthetic resins such as styrene-butadiene resin, acrylic ester resin, methacrylic ester resin, and fluororesin represented by polyvinylidene fluoride can be used.
• the coating liquid used to form the coating layer includes, in addition to the inorganic particles and the binder resin, various dispersants such as polyacrylic acid and sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, Various thickeners such as polyethylene oxide, various additives such as various wetting agents, preservatives and antifoaming agents can be blended as necessary. Among these additives, agents such as thickeners and wetting agents can be suitably used for adjusting the degree of penetration of the coating liquid in the present invention.
• the coating method when the coating layer is provided on the substrate for example, a conventionally known air doctor coater, blade coater, knife coater, rod coater, squeeze coater, impregnation coater, gravure coater, Examples include a kiss roll coater, a die coater, a reverse roll coater, a transfer roll coater, and a spray coater.
• the coating amount of the coating layer containing inorganic particles is preferably 1.0 to 20.0 g / m 2 , more preferably 4.0 to 15.0 g / m 2 as a dry solid content. More preferred. If the coating layer is less than 1.0 g / m 2 , the surface of the base paper cannot be sufficiently covered, the pore diameter becomes large, and a short circuit occurs. There is a case. On the other hand, when the adhesion amount of the coating layer exceeds 20.0 g / m 2 , it may be difficult to reduce the thickness of the separator.
• base papers 1 to 10 were produced by the following method with the fiber blending and basis weight shown in Table 1.
• the freeness of the aramid fiber is a value measured by the method described in JIS P8121-2: 2012.
• the base papers 1 to 10 were subjected to thermal calendering treatment with a thermal calendering device under the conditions described in Tables 2 to 4, and substrates of Examples 1 to 21 and Comparative Examples 1 to 6 were produced.
• the “type” described in each table describes the method of the thermal calendar device. In the two-stage process, “Linear pressure at the first nip / Linear pressure at the second nip” is indicated in the “Linear pressure” column.
• Heated metal roll Thermal calendering was performed using a heat calender device of the heated metal roll configuration.
• S Thermal calendering was performed using a thermal calender device with a heated metal roll-resin roll configuration. As the resin roll, a roll wound with a synthetic resin having a Shore hardness of D92 was used.
• HH Heated metal roll-A two-stage process (2 nips) using a heat calender device of heated metal roll configuration so that the heated metal roll contacts the front and back surfaces of the base paper. Thermal calendering was performed.
• SS Two-stage thermal calendering (two nips) so that the heated metal roll is in contact with the front and back surfaces of the base paper using a heated calender device with a heated metal roll-resin roll configuration Went.
• resin roll a roll wound with a synthetic resin having a Shore hardness of D92 was used.
• SH Using a heat calender device having a heated metal roll-resin roll configuration, the heated metal roll is subjected to a heat calender treatment so that the heated metal roll contacts the surface of the base paper.
• -Thermal calendering was carried out using a thermal calender device in the form of a heated metal roll.
• a roll wound with a synthetic resin having a Shore hardness of D92 was used.
• the X-ray diffraction intensity of the substrate of the present invention was measured under the following conditions using an X-ray diffraction intensity measuring device “X′PertPRO” manufactured by PANalytical. 1) Measurement of X-ray diffraction intensity Tube voltage 45 kV Tube current 40mV Measurement area The measurement area in one measurement is 15mm x 20mm For measuring points one substrate, and samples so that their measuring points are in contact was measured at 7 points or more measurement points (2100 mm 2 or more in the measurement area). In addition, when the frequency
• Peak detection Among the diffraction peaks derived from the crystal part of the PET fiber, the X-ray diffraction intensity is the strongest peak intensity at a diffraction angle of 2 ⁇ 26 ° (diffraction angle of 25.5 to 26.5 °). (Unit: cps).
• ⁇ Specific tensile strength> With reference to JIS P 8113, a tensile test of the substrate sample was performed at a test width of 50 mm, a span between chucks of 100 mm, and a tensile speed of 300 mm / min. About the sample of a base material, it measured about the flow direction (MD) of the base material, and the width direction (CD), respectively, and measured the tensile strength. By dividing the total tensile strength of the tensile strength obtained with respect to the flow direction (MD) and the tensile strength obtained with respect to the lateral direction (CD) by the basis weight, the specific tensile strength (unit: N ⁇ m / g). If the specific tensile strength is 95 N ⁇ m / g or more, it can be used practically.
• ⁇ Defect frequency evaluation> The substrate was visually inspected over a paper width of 400 mm and a length of 500 m, and evaluated according to the following evaluation criteria.
• ⁇ Winding form> The winding form when the paper width of 400 mm and the length of 1000 m were wound was visually inspected and evaluated according to the following evaluation criteria.
• a coating solution was prepared by mixing and stirring 10 parts of a butadiene resin (SBR) emulsion (solid content concentration 50%). Using the gravure coater, the coating liquid is dried solid, and the coating amount is 15.0 g / m 2 , so that one side of the substrate (however, when the heated metal roll has a different number of contacts, The surface having a large number of contacts) was coated and dried to produce lithium ion secondary battery separators of Examples 1 to 21 and Comparative Examples 1 to 6.
• SBR butadiene resin
• Example 6 By comparing Example 6 and Comparative Example 2, it can be seen that when the COV (coefficient of variation) exceeds 12.0%, a crack defect occurs in the base material, and the winding shape of the winding deteriorates.
• the reason why the coefficient of variation exceeded 12.0% in Comparative Example 2 was that the calendar paper pressure was increased too much to treat the base paper, the crystallization of the PET fiber progressed, and the specific diffraction intensity was 300 cps / (g / m 2 ) It was above, but the coefficient of variation exceeded 12.0%.
• Example 6 By comparing Example 6 with Comparative Examples 3 and 4, the specific diffraction intensity is less than 300 cps / (g / m 2 ), and when the COV (coefficient of variation) exceeds 12.0%, the strength of the substrate is increased. It is weak, the penetration of the coating liquid is easy to proceed, the workability during coating is poor, and the coating layer strength of the lithium ion secondary battery separator is also reduced.
• the specific diffraction intensity was less than 300 cps / (g / m 2 ) and the COV (coefficient of variation) exceeded 12.0% because the thermal calendar treatment of the substrate was not sufficient. In other words, the method of applying heat from the calendar roll to the base paper became non-uniform, resulting in insufficient crystallization of the PET fibers, and the uniformity of the crystallinity was impaired.
• the average fiber diameter of the PET fibers is 9.0 ⁇ m or less even when a base paper containing PET fibers and other fibers other than PET fibers is used.
• the specific X-ray diffraction intensity derived from PET fiber is 300 cps / (g / m 2 ) or more and the COV (coefficient of variation) is 12.0% or less, it is understood that the substrate is excellent in strength. It can be seen that in Comparative Example 6 in which the COV (coefficient of variation) exceeds 12.0%, the strength is hardly developed. In Comparative Example 6, since the PET fiber content was too low, the bonding strength between the PET fibers was reduced, and it was considered that the strength became difficult to develop.
• Example 6 and Comparative Examples 2 and 4 By comparing Example 6 and Comparative Examples 2 and 4 with Examples 12 to 14, and performing a calendering process with a calender device composed of a resin roll and a heated metal roll, the heated metal roll and It can be seen that it is possible to provide a base material that is superior in strength and has fewer defects such as cracks than performing a calendering process with a calendering device composed of a heated metal roll. Moreover, it turns out that the specific X-ray-diffraction intensity
• the base material for a lithium ion secondary battery separator and the lithium ion secondary battery separator of the present invention can be suitably used for lithium ion secondary batteries such as lithium ion secondary batteries and lithium ion polymer secondary batteries.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Inorganic Chemistry (AREA)
• Cell Separators (AREA)
• Paper (AREA)
• Materials Engineering (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (1)

Family

ID=48947403

Family Applications (1)

Country Status (5)

Cited By (2)

Families Citing this family (7)

Citations (15)

Family Cites Families (6)

• 2012
  • 2012-12-26 JP JP2012282289A patent/JP6018498B2/ja active Active
• 2013
  • 2013-01-25 CN CN201380007317.1A patent/CN104067410B/zh active Active
  • 2013-01-25 US US14/376,531 patent/US9570726B2/en active Active
  • 2013-01-25 WO PCT/JP2013/052297 patent/WO2013118639A1/ja not_active Ceased
  • 2013-01-25 EP EP13746236.2A patent/EP2814085B1/en not_active Not-in-force

Patent Citations (15)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events