JP2006187891A - Laminate, its manufacturing method and its application - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate excellent in shutdown function and strength, its manufacturing method and a secondary cell using the laminate. <P>SOLUTION: The laminate comprises a base material layer and the closure layer laminated at least on one side of the base material layer. The base material layer has a large number of through-holes and contains a plastic A while the closure layer has a large number of through-holes and contains a plastic B and a foaming agent. Further, the plastic B has a softening temperature lower than that of the plastic A and the foaming agent is expanded at a predetermined temperature or above. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminate, a manufacturing method thereof, and a secondary battery using the same.

  In recent years, various organic electrolyte secondary batteries have been developed as batteries capable of achieving high capacity, high voltage, and high energy density. In this organic electrolyte secondary battery (for example, a lithium ion battery), a porous film capable of circulating ions along with the electrolyte is provided as a separator between a positive electrode and a negative electrode that are arranged to face each other.

  In addition, since there is a risk that the organic electrolyte secondary battery may ignite due to a temperature increase due to a short circuit, the heat generated before the temperature inside the battery reaches the melting point of lithium or the flash point of the organic electrolyte. It is necessary to stop the battery reaction that causes it.

  Thus, various attempts have been made to add various devices to the separator between the positive electrode and the negative electrode. For example, a shutdown function is imparted by a separator containing a heat-meltable material (for example, see Patent Documents 1, 2, and 3).

  Here, “shutdown function imparted by a separator containing a heat-meltable material” means that when the battery is heated due to Joule heat due to a short circuit and the temperature rises rapidly, the separator, that is, the heat-meltable material is above a certain temperature By deforming and closing the pores of the separator, the flow of ions is hindered and the battery reaction is stopped. Therefore, by “providing the shutdown function by the separator containing the heat-meltable material”, the temperature inside the battery does not reach the melting point of lithium or the flash point of the organic electrolyte, and an ignition accident or the like can be prevented.

However, even if the shutdown function is activated due to the temperature rise, the temperature rise does not stop immediately. For this reason, the film itself may melt and the isolation may be impaired.
Furthermore, since the strength of the separator is insufficient, the separator may be damaged during battery assembly or use, resulting in a short circuit.

As measures for improving such problems, it has been proposed to widen the temperature range in which the shutdown function works and to improve the strength (see, for example, Patent Documents 4, 5 and 6). These are techniques for laminating a heat-meltable material on a porous membrane or a nonwoven fabric substrate. However, these techniques sometimes have insufficient shutdown functions. In addition, even when the battery generated heat due to Joule heat due to a short circuit and the temperature rose rapidly, the shutdown function did not work quickly if the hole was blocked due to melting.
Japanese Patent No. 2642206 JP-A-6-212006 Japanese Patent Laid-Open No. 8-138643 Japanese Patent Publication No. 4-1692 JP-A-60-52 JP 61-232560 A

  The present invention solves such problems of the prior art, and an object of the present invention is to provide a laminate having an excellent shutdown function and strength, as well as a manufacturing method thereof and a secondary using the same. It is to provide a battery.

  That is, a laminated body having a base material layer and a blocking layer laminated on at least one surface of the base material layer, wherein the base material layer has a large number of through holes and contains plastic A. The closing layer has a large number of through-holes and contains plastic B and a foaming agent. Further, the plastic B has a softening temperature lower than that of the plastic A, and the foaming agent has a predetermined value. It expands above the temperature.

  According to the laminate of the present invention, since the strength is maintained by the base material layer, the laminate is not damaged during assembly or use, and the laminate itself is not melted and damaged.

  Furthermore, since the plugging layer containing the plastic B and the foaming agent is laminated on the plugging layer, the plastic B melts at a certain temperature or more and expands at a certain temperature or more. A layer can be formed thinly, without disturbing the flow of ions and the like, and when the temperature exceeds a certain temperature, a quick and sufficient shutdown function can be obtained.

  In this specification, the “shutdown function” means a function that not only prevents the flow of ions but also allows adjustments such as closing or reducing the through-hole in order to prevent the flow of other things. May be.

  In the laminate of the present invention, the foaming agent is preferably a thermally expandable microcapsule.

  Thus, by laminating the sealing layer containing the plastic B and the thermally expandable microcapsule on the base material layer, the plastic B melts at a certain temperature or higher, and the thermally expandable microcapsule has a certain temperature. Since it expands at a range of temperatures, it is possible to obtain an excellent shutdown function that is sufficient and quick at a range of temperatures.

  In the laminate of the present invention, the shell component of the thermally expandable microcapsule is made of a thermoplastic resin polymerized mainly with acrylonitrile, and the internal component of the thermally expandable microcapsule is normal butane, It is preferably composed of at least one selected from the group consisting of normal pentane and normal hexane.

  Thus, by using a thermoplastic resin obtained by polymerizing acrylonitrile as a main component as the shell component of the thermally expandable microcapsule, a thermally expandable microcapsule having excellent heat resistance and chemical resistance can be used.

  In the laminate of the present invention, the plastic B preferably contains polyethylene.

  In the laminate of the present invention, it is preferable that the plastic A contains polypropylene.

  In the laminate of the present invention, the expansion start temperature of the thermally expandable microcapsule is preferably 50 ° C. or higher and 200 ° C. or lower.

  If the expansion start temperature of the thermally expandable microcapsule is less than 50 ° C., the shutdown function may be exhibited at a low temperature, while if it exceeds 200 ° C., the shutdown function may not be exhibited even at a high temperature.

  In the laminate of the present invention, the plastic B preferably has a softening temperature of 50 ° C. or higher and 200 ° C. or lower.

  If the softening temperature of the plastic B is less than 50 ° C., the shutdown function may be exhibited at a low temperature, while if it exceeds 200 ° C., the shutdown function may not be exhibited even at a high temperature.

  Moreover, it is preferable that the thickness of the said obstruction | occlusion layer is 5 to 200 micrometers in the laminated body of this invention.

  When the thickness of the blocking layer is less than 5 μm, the shutdown function may be insufficient. On the other hand, when the thickness exceeds 200 μm, the circulation of ions or the like may be insufficient, which may be economically disadvantageous. is there.

  In the laminate of the present invention, it is preferable that the closing layer contains 5 parts by weight or more and 80 parts by weight or less of thermally expandable microcapsules with respect to 100 parts by weight of plastic B.

  If the thermally expandable microcapsule is less than 5 parts by weight relative to 100 parts by weight of the plastic B, the shutdown function may be insufficient. On the other hand, if it exceeds 80 parts by weight, the circulation of ions and the like becomes insufficient. Moreover, there is a risk that it will be economically disadvantageous.

  Moreover, it is preferable that the laminated body of this invention is 1 micrometer or more and 20 micrometers or less in the average particle diameter of the said thermally expansible microcapsule.

  If the average particle size of the thermally expandable microcapsule is less than 1 μm, the shutdown function may be insufficient, while if it exceeds 20 μm, the circulation of ions or the like may be insufficient.

  In the present specification, the “average particle diameter” means a value obtained by averaging the longest diameter and the shortest diameter of the particles.

  And the manufacturing method of the laminated body of this invention is a manufacturing method of the laminated body which has a base material layer which has many through-holes and contains the plastic A, and an obstruction | occlusion layer, Comprising: At least 1 of the said base material layer Forming a resin layer on one surface by applying a resin composition liquid containing a plastic B having a softening temperature lower than that of the plastic A, a foaming agent that expands above a predetermined temperature, and a water-soluble substance; And a removing step of forming a blocking layer by dissolving the water-soluble substance from the resin layer.

  According to the method for producing a laminate of the present invention, by removing the water-soluble substance from the resin layer by dissolving it, a large number of through holes can be formed in the blocking layer. Compared with the case where it forms, the outstanding intensity | strength can be obtained.

  Furthermore, the present invention is a secondary battery in which the laminate of the present invention is used as a separator.

  According to the secondary battery of the present invention, since the strength is maintained by the base material layer, it is not damaged when the battery is assembled or used, and the laminate itself is not melted and damaged at a high temperature. .

  Furthermore, by laminating the blocking layer containing the plastic B and the foaming agent on the base material layer, the plastic B melts at a certain temperature or higher and expands at a certain temperature or higher. A blocking layer can be formed thinly, without impeding the flow of ions, and a rapid and sufficient shutdown function can be obtained at a certain temperature or higher.

  Accordingly, the temperature inside the battery does not reach the melting point of lithium or the flash point of the organic electrolyte, and an ignition accident or the like can be prevented.

  And this invention is industrial material material, for example, it is used as hot-time hot-air blockage clothing, hot-time heat or smoke blockage building material, and industrial filtration material.

  According to the laminate of the present invention, since the strength is maintained by the base material layer, the laminate is not damaged during assembly or use, and the laminate itself is not melted and damaged.

  Furthermore, by laminating the blocking layer containing the plastic B and the foaming agent on the base material layer, the plastic B melts at a certain temperature or higher and expands at a certain temperature or higher. A blocking layer can be formed thinly, without disturbing the flow of ions and the like, and when the temperature exceeds a certain temperature, a quick and sufficient shutdown function can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of the laminate of the present invention at a temperature lower than a certain temperature, and FIG. 2 is a cross-sectional view showing the laminate shown in FIG. is there.

  The laminated body 1 a includes a base material layer 2 having a large number of through holes 5 and a blocking layer 3 a having a large number of through holes 8.

  The base material layer 2 is made of plastic A4. The plastic A4 is excellent in strength and is not melted and deformed even at a high temperature.

  The blocking layer 3a is made of plastic B6a and a foaming agent 7a. The plastic B6a has a softening temperature lower than that of the plastic A4 and melts at a certain temperature or higher, and the foaming agent 7a expands at a certain temperature or higher.

  Therefore, the laminate 1a has a through-hole in which the strength can be maintained by the base material layer 2 and the blocking layer 3a is thin and can prevent the flow of ions and the like without interrupting the flow of ions and the like. It has become a thing.

  On the other hand, the laminated body 1b has the base material layer 2 which has many through-holes 5, and the obstruction | occlusion layer 3b. The blocking layer 3b is made of molten plastic B6b and expanded foaming agent 7b. Therefore, the laminated body 1b has an excellent shutdown function by forming the blocking layer 3b having a sufficient thickness while maintaining the strength even at a high temperature by the base material layer 2.

  In addition, in the laminated body 1a, if there exists the foaming agent 7a which entered the through-hole 5, in the laminated body 1b, the foaming agent 7b may expand in the through-hole 5 and block the through-hole 5. Furthermore, in the laminated body 1b, the melted plastic B6b may flow into the through hole 5 and close the through hole 5.

  The thickness of the base material layer is preferably 5 μm or more.

  The thickness of the blocking layer is preferably 5 μm or more and 200 μm or less, and more preferably 5 μm or more and 50 μm or less. The thickness of the blocking layer at a certain temperature or higher is preferably 7 μm or more and 1000 μm or less, and more preferably 7 μm or more and 500 μm or less.

  The average particle diameter of the foaming agent is preferably 1 μm or more and 20 μm or less, and the average particle diameter of the foaming agent during expansion is preferably 2 μm or more and 300 μm or less.

  The blocking layer preferably contains a foaming agent in an amount of 5 parts by weight to 80 parts by weight with respect to 100 parts by weight of the plastic B.

The expansion start temperature of the foaming agent is preferably 50 ° C. or higher and 200 ° C. or lower, and more preferably 70 ° C. or higher and 170 ° C. or lower.
The softening temperature of the plastic B is preferably 50 ° C. or higher and 200 ° C. or lower, and more preferably 70 ° C. or higher and 150 ° C. or lower.

  The softening temperature of the plastic B may be equal to or higher than the expansion start temperature of the foaming agent, may be equal to or lower than the expansion start temperature of the foaming agent, or may be near the expansion start temperature of the foaming agent. Good.

  The porosity of the laminate is preferably 30% or more and 80% or less, and more preferably 40% or more and 70% or less. If the porosity is less than 30%, the circulation of ions and the like may be deteriorated. On the other hand, if it exceeds 80%, the strength may be lowered.

  The air permeability (measurement of ion circulation) of the laminate is not limited, but the value measured by a method (Gurley tester method) based on JIS P8117 is 1 sec / 100 cc Air or more and 800 sec / 100 cc Air or less. preferable. If the air permeability is less than 1 sec / 100 cc Aircc, the strength may be lowered. On the other hand, if the air permeability exceeds 800 sec / 100 cc Air, the circulation of ions and the like may be deteriorated. The air permeability of the laminate when the temperature is above a certain temperature is preferably 800 sec / 100 cc Air or more.

  Examples of the plastic A and / or plastic B include olefin resins such as polyethylene and propylene, acetals, acrylics, methyl methacrylate, acetylcellulose, nitrocellulose, ethylene / acrylic, fluororesins, polyacrylonitrile, polyamides such as nylon, and the like. , Polybutadiene / acrylonitrile, polybutadiene / styrene, polycarbonate, saturated polyester such as polyethylene terephthalate, polyhydroxy ether, polyimide, polyphenylene oxide, polystyrene, polysulfone, polyvinyl acetate, ethylene / vinyl acetate copolymer, polyvinyl alcohol, polyvinyl alkyl ether , Polyvinyl butyral, polyvinyl chloride, polyvinyl methyl ether, polyurethane, alkyd Casein, cyanoacrylate, diallyl phthalate, epoxy and modified products thereof, furan, melamine formaldehyde, phenol formaldehyde, phenol furfural, unsaturated polyester, polysulfide, resorcinol / phenol formaldehyde, silicone, urea formaldehyde and other thermosetting resins, epoxy Novolak, epoxy-phenolic, epoxy-polysulfide, epoxy-silicone, phenolic-butyral, phenolic-nitrile, phenolic-polyamide, polyamide-epoxy, polyimide-epoxy, silicone-vinylphenolic, silicone-phenolic, vinyl formal-phenolic, vinyl butyral -Alloys such as phenolic can be mentioned , Preferably may be mentioned olefin-based resin. More preferably, examples of the plastic A include polypropylene, and examples of the plastic B include polyethylene.

  Examples of the foaming agent include sodium bicarbonate, a mixture of sodium bicarbonate and an organic acid such as citric acid, azo foaming agents such as azodicarbonamide and barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, N, Nitroso-based blowing agents such as N′-dimethyl-N, N′-dinitrosotephthalamide, sulfohydrazide-based blowing agents such as p, p′-oxybisbenzenesulfonylhydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, etc. Can be mentioned. These may be used alone or in combination of two or more.

  In the above-described laminate, a blocking layer containing thermally expandable microcapsules may be used.

  FIG. 3 is a cross-sectional view showing another example of the embodiment of the laminated body of the present invention at a temperature lower than a certain temperature. In FIG. 3, the configuration is the same as that of the laminate of FIG. 1 except that the foaming agent is changed to a thermally expandable microcapsule. Therefore, only the portion related to the thermally expandable microcapsule will be described.

  The closing layer 13 is made of plastic B 16 and thermally expandable microcapsules 17. Further, the thermally expandable microcapsule 17 includes an internal component 17a and a shell component 17b. The shell component 17b melts at a certain temperature or higher, and the internal component 17a expands at a certain range of temperature.

  When the blocking layer 13 containing such a heat-expandable microcapsule 17 is used, the shell component 17b melts at a certain temperature or higher, and the internal component 17a expands at a certain temperature range. Thus, since the thermally expandable microcapsule 17 expands at a certain range of temperatures, an excellent shutdown function that is sufficient and quick at a certain range of temperatures can be obtained.

The average particle diameter of the thermally expandable microcapsule is preferably 1 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less. The average particle size of the thermally expandable microcapsule during expansion is preferably 2 μm or more and 300 μm or less, and more preferably 2 μm or more and 50 μm or less.
The closing layer preferably contains 5 to 80 parts by weight of heat-expandable microcapsules with respect to 100 parts by weight of plastic B, and more preferably 10 to 30 parts by weight.

The expansion start temperature of the thermally expandable microcapsule is more preferably 50 ° C. or higher and 200 ° C. or lower, and particularly preferably 70 ° C. or higher and 170 ° C. or lower.
The thermally expandable microcapsules are preferably those obtained by microcapsulating low-boiling hydrocarbons that use a thermoplastic resin as a shell component and become gaseous at or below the softening temperature of the thermoplastic resin.

  Examples of the shell component of the thermally expandable microcapsule include a thermoplastic resin obtained by polymerizing acrylonitrile, methacrylonitrile, acrylamide, methacrylic acid or a salt thereof, and the like. And thermoplastic resins.

  As an internal component of the thermally expandable microcapsule, a low boiling point hydrocarbon can be used. Specific examples include isobutane, normal butane, normal pentane, isopentane, normal hexane, cyclohexane, normal heptane, petroleum ether, neopentane, Propane, propylene, butene, methane halides (methyl chloride, methylene chloride, etc.), tetraalkylsilane, and the like can be mentioned, and normal butane, normal pentane, and normal hexane are preferred. These may be used alone or in combination of two or more.

  Furthermore, the thermally expandable microcapsule preferably contains 10 to 20% by weight of low-boiling hydrocarbons.

  And as above-mentioned laminated body, two layers of base material layer / occlusion layer, 3 layers of obstruction | occlusion layer / base material layer / occlusion layer, and also the laminated structure of a multilayer from 3 layers may be sufficient as mentioned above. Furthermore, layers other than these may be laminated, and specific examples include an antistatic layer, a mat layer, a hard coat layer, a slippery coat layer, an easy adhesion layer, and an adhesive layer.

  Furthermore, the base material layer and / or the blocking layer may contain a lubricant, an antioxidant, an ultraviolet absorber, a plasticizer, a molding aid and the like.

Next, an example of the manufacturing method of the laminated body of this invention is demonstrated (refer FIG. 4).
The method for producing a laminate 1a of the present invention is a method for producing a laminate 1a having a substrate layer 2 having a large number of through-holes 5 and containing plastic A4, and a blocking layer 3a. And a removing step.

(1) Formation process As the base material layer 2, one having a large number of through holes 5 and containing plastic A4 is used (see FIG. 4a). On the other hand, a resin composition liquid containing a plastic B6a having a softening temperature lower than that of the plastic A4, a foaming agent 7a that expands above a predetermined temperature, and a water-soluble substance 9 is prepared. For example, plastic B6a, foaming agent 7a and water-soluble substance 9 are put into a solvent such as water, and sufficiently stirred and uniformly dispersed by a mixer such as a super mixer, a ribbon blender, or a V-blender to obtain a resin composition liquid. Prepare. And the said resin composition liquid is apply | coated to the at least 1 surface of the base material layer 2, and the resin layer 10 is formed (refer FIG. 4b). Examples of the method for applying the resin composition liquid include a roll coater, a flow coater, spraying, dipping, brushing, and the like. The resin layer 10 may be heated at a temperature not lower than the softening temperature of the plastic B6a and not higher than the expansion start temperature of the foaming agent 7a.

(2) Removal process The water-soluble substance 9 is removed from the resin layer 10 by washing with water or the like of 20 ° C. or more and 50 ° C. or less by a general extraction method such as a batch method or a countercurrent multistage method (see FIG. 4c). That is, by removing the water-soluble substance 9 by dissolving it, the blocking layer 3a having a large number of through holes 8 and containing the plastic B6a and the foaming agent 7a is formed. In addition to water, a material that can dissolve the water-soluble substance 9 after forming the resin layer 10 and that does not dissolve the plastic B6a after forming the resin layer 10 may be used.

  The plastic B in the resin composition liquid is preferably a water-dispersible polymer and / or a water-soluble polymer. The “water-dispersible polymer” means a polymer that is dispersed in an aqueous solvent using an emulsifier or the like, while the “water-soluble polymer” is self-dispersed in an aqueous solvent without using an emulsifier or the like. Means a polymer. Among these, a water dispersible polymer is more preferable. This is because it is dispersed using an emulsifier or the like, so that the solubility of water or the like is low, and it does not dissolve in the removing step after the resin layer is formed.

  Examples of the water-soluble substance include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose sulfate, polyethylene oxide, gelatin, cationized starch, casein, sodium polyacrylate, and styrene-maleic anhydride copolymer. Sodium salts, sodium polystyrene sulfonate, surfactants and the like can be mentioned, and polyvinyl alcohol, gelatin, cationized starch and surfactants can be preferably mentioned. These may be used alone or in combination of two or more.

  Furthermore, you may make the said resin composition liquid contain a thickener (acrylic-acid type alkali thickener) etc.

  The concentration of the water-soluble substance in the resin composition liquid is preferably 1% by weight or more and 30% by weight or less.

  The concentration of the solvent in the resin composition liquid is preferably 30% by weight or more and 80% by weight or less.

  Next, an example of the secondary battery of the present invention will be described.

  The secondary battery of the present invention has a normal configuration except that the laminate of the present invention is used as a separator.

  That is, using a material containing lithium as a positive electrode active material, using a material capable of occluding and releasing lithium as ions as a negative electrode active material, and an electrolyte and an organic solvent made of a compound containing lithium and fluorine as an electrolytic solution An organic electrolytic solution containing can be used.

  Examples of the positive electrode active material include lithium metal oxides such as lithium cobaltate and lithium manganate. Then, a positive electrode active material and activated carbon, various cokes, carbon black, a binder, a solvent, and the like as a conductive agent are blended and applied to a current collector such as aluminum and dried to be a positive electrode.

  Examples of the negative electrode active material include coke, graphite, and amorphous carbon. And what mix | blended the negative electrode active material, the binder, the organic solvent, etc., apply | coated and dried to collectors, such as copper foil, can be used as a negative electrode.

Examples of the electrolyte include LiClO ₄ , LiA _S F ₆ , LiPF ₄ , LiBF ₄ , LiBr, LiCF ₃ SO _{3, and the} like. Examples of the organic solvent include propylene carbonate, ethylene carbonate, γ-butyrolactone, Examples include dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, and tetrahydrofuran.

  Examples of the structure of the secondary battery include, for example, a paper-type battery or a laminated battery having a positive electrode, a negative electrode, and a separator as a single layer or a multilayer, a positive electrode, a negative electrode, and a cylindrical battery in which a separator is wound in a roll shape. it can.

And the laminated body of this invention used as a separator for a secondary battery is a laminated body which has a base material layer and the obstruction | occlusion layer laminated | stacked on the at least 1 surface of the said base material layer, Comprising: In addition to having a large number of through-holes and containing polypropylene, the blocking layer has a number of through-holes and containing polyethylene and thermally expandable microcapsules, and the polyethylene is softer than the polypropylene. It is preferable to have a temperature.
According to such a secondary battery of the present invention, the strength is maintained by the base material layer containing polypropylene, so that it is not damaged during battery assembly or use, and the laminate itself is melted and damaged. It will never happen.

  Furthermore, by laminating a blocking layer containing polyethylene and thermally expandable microcapsules on the base material layer, the polyethylene melts at a certain temperature or higher, and the thermally expandable microcapsules have a certain range of temperatures. Therefore, the blocking layer can be formed thinly, without disturbing the flow of ions, and when the temperature exceeds a certain temperature, a quick and sufficient shutdown function can be obtained.

  Accordingly, the temperature inside the battery does not reach the melting point of lithium or the flash point of the organic electrolyte, and an ignition accident or the like can be prevented.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1
(1) Formation process A base material layer (trade name: NF sheet, manufactured by Tokuyama Corporation; thickness: 100 μm, porosity: 60%) having a large number of through holes and made of polypropylene was used. On the other hand, water-dispersible low-density polyethylene (trade name: Chemipearl M200, manufactured by Mitsui Chemicals, Inc .; solid content 40 wt%, softening temperature 75 ° C.) 100 g and thermally expandable microcapsules (trade name: Matsumoto Microsphere F-) 80VS, manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; expansion start temperature 150-160 ° C., average particle size 5-8 μm 20 g and polyoxyethylene alkyl ether surfactant (trade name: Neugen EA197, Daiichi Kogyo Seiyaku Co., Ltd.) ); Solid content 50 wt%) 5 g, acrylic acid alkali thickener (trade name: Boncoat 3750, manufactured by Dainippon Ink & Chemicals, Inc.) 3 g and caustic soda (solid content 5 wt%) 0.3 g The resin composition liquid was obtained by sufficiently stirring and uniformly dispersing with a propeller mixer. And the resin composition liquid was apply | coated to one surface of a base material layer with Wet18g / cm < ² > with the bar coater, and the resin layer was formed. Next, the resin layer was heated at 130 ° C. for 5 minutes.
(2) Removal step The polyoxyethylene alkyl ether surfactant and the like were removed from the resin layer by immersing in 50 ° C. water for 60 minutes. Next, it was dried at 100 to 120 ° C. for 5 minutes to obtain a laminate according to Example 1.

(Example 2)
(1) Formation process The base material layer (brand name: NF sheet) which has many through-holes and consists of polypropylene was used. On the other hand, 100 g of heated and melted polyethylene (weight average molecular weight Mw 300000) and 10 g of polyoxyethylene nonylphenol ether are mixed with a propeller mixer, and further mixed with 100 g of water (temperature 80 ° C.), and then passed through a high-pressure emulsifier. Water-dispersed polyethylene (with emulsifier) having a solid content of 50 to 53% by weight was obtained. Further, 100 g of water-dispersed polyethylene (type using emulsifier), 5 g of sodium bicarbonate, 5 g of a polyoxyethylene alkyl ether type surfactant (trade name: Neugen EA197) and an alkali thickener based on acrylic acid (trade name: Boncoat 3750) ) 3 g and caustic soda (solid content 5 wt%) 0.3 g were sufficiently stirred and uniformly dispersed by a propeller mixer to obtain a resin composition liquid. And the resin composition liquid was apply | coated to one surface of a base material layer with Wet18g / cm < ² > with the bar coater, and the resin layer was formed. Next, the resin layer was heated at 120 ° C. for 5 minutes.
(2) Removal step The polyoxyethylene alkyl ether surfactant, polyoxyethylene nonylphenol ether, and the like were removed from the resin layer by immersing in 50 ° C. water for 60 minutes. Next, it was dried at 100 to 120 ° C. for 5 minutes to obtain a laminate according to Example 2.

(Comparative Example 1)
A laminated body according to Comparative Example 1 was obtained in the same manner as in Example 1 except that 50 g of water-dispersed low-density polyethylene was used instead of 20 g of thermally expandable microcapsules.
<Evaluation of laminate>
(1) Thickness The thickness of the laminate was measured with a dial gauge (Peacock Co., Ltd.). The results are shown in Table 1.
(2) Porosity The porosity was calculated by the following formula. The results are shown in Table 1.
Porosity = (1-100X / 0.95Y) × 100 [%]
X: Weight of the laminate [g / dm ² ]
Y: Thickness of the laminate [μm]
(3) Strength According to the method defined in JIS-K7127, the tensile strength was measured at 25 ° C. and 65% RH using a tensile tester (manufactured by Shimadzu Corporation). The sample piece was cut into a strip shape having a length of 15 cm, a width of 1.5 cm, and a thickness of 0.01 cm in the measurement direction, an initial tensile chuck distance was 10 cm, and a tensile speed was 200 mm / min. The results are shown in Table 1.
(4) Air permeability Measured according to JIS P8117. A B-type Gurley Densometer (manufactured by Toyo Seiki Co., Ltd.) was used as a measuring device. The time required for 100 cc of air to pass through was measured and used as the air permeability (Gurley value).

Further, the air permeability was measured after applying a load of 6 kg / 600 cm ² and holding at 150 ° C. for 1 minute, 2 minutes and 5 minutes. The results are shown in Table 1.

  From the results shown in Table 1, the laminate according to Example 1 has a low initial air permeability and an air permeability after 1 minute of 150 ° C. of 1200 sec / 100 cc Air or more, and has a sufficient and quick excellent shutdown function. It was a thing. Further, the laminate according to Example 2 had a low initial air permeability and an air permeability of 900 sec / 100 cc Air after 150 minutes at 150 ° C., and had a sufficient and quick excellent shutdown function.

  On the other hand, the laminated body according to Comparative Example 1 was not satisfactory because the air permeability after 5 minutes at 150 ° C. was 500 sec / 100 cc Air.

It is sectional drawing which shows an example of embodiment of the laminated body of this invention at the time of less than a fixed temperature. It is sectional drawing which shows the laminated body shown in FIG. 1 at the time of more than a fixed temperature. It is sectional drawing which shows another example of embodiment of the laminated body of this invention at the time of less than a fixed temperature. It is a figure which shows an example of the manufacturing method of the laminated body of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminated body 2 Base material layer 3, 13 Closure layer 4, 6, 16 Plastic 5, 8 Through-hole 7 Foaming agent 9 Water-soluble substance 10 Resin layer 17 Thermally expansible microcapsule

Claims (12)

A laminate having a base material layer and a blocking layer laminated on at least one surface of the base material layer,
The base material layer has a large number of through holes and contains plastic A,
The blocking layer has a large number of through holes, and contains plastic B and a foaming agent,
Furthermore, the plastic B has a softening temperature lower than that of the plastic A, and the foaming agent expands at a predetermined temperature or higher. The laminate according to claim 1, wherein the foaming agent is a thermally expandable microcapsule. The shell component of the thermally expandable microcapsule is made of a thermoplastic resin polymerized mainly with acrylonitrile, and the internal component of the thermally expandable microcapsule is from the group consisting of normal butane, normal pentane and normal hexane. The laminate according to claim 2, comprising at least one selected. The said plastic B is a laminated body in any one of Claims 1-3 containing polyethylene. The laminate according to any one of claims 1 to 4, wherein the plastic A contains polypropylene. The layered product according to any one of claims 2 to 5, wherein an expansion start temperature of the thermally expandable microcapsule is 50 ° C or higher and 200 ° C or lower. The laminated body according to any one of claims 1 to 6, wherein the plastic B has a softening temperature of 50C or higher and 200C or lower. The laminate according to any one of claims 1 to 7, wherein the blocking layer has a thickness of 5 µm to 200 µm. The said obstruction | occlusion layer is a laminated body in any one of Claims 2-8 containing 5 to 80 weight part of thermally expansible microcapsules with respect to 100 weight part of plastics B. The laminate according to any one of claims 2 to 9, wherein an average particle diameter of the thermally expandable microcapsule is 1 µm or more and 20 µm or less. A method for producing a laminate having a substrate layer having a large number of through holes and containing plastic A, and a blocking layer,
A resin layer is applied by applying a resin composition liquid containing plastic B having a softening temperature lower than that of plastic A, a foaming agent that expands above a predetermined temperature, and a water-soluble substance to at least one surface of the base material layer. Forming step of forming,
And a removing step of forming a blocking layer by dissolving the water-soluble substance from the resin layer. A secondary battery in which the laminate according to any one of claims 1 to 10 is used as a separator.

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