JP2019169336A - Porous film having fine pattern - Google Patents

Abstract

To provide a porous film having a structure in which Li dendrite hardly occurs even if being arranged in a lithium ion secondary battery, and to provide a lithium ion secondary battery with improved life characteristics.SOLUTION: A pattern region (11) having a concave portion (11b) or a convex portion (11a) on at least one surface of a porous film. A length (L) of a long axis of the pattern region (11) which has the recessed portion (11b) or convex portion (11a) is 0.5 μm or more and 100 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a porous film and the like.

  With the recent development of electronic technology or increasing interest in environmental technology, various electrochemical devices are used. In particular, there are many demands for energy saving, and the expectation for electrochemical devices that can contribute to this is increasing.

  Lithium ion secondary batteries, which are typical examples of power storage devices and typical examples of non-aqueous electrolyte batteries, have been used mainly as power sources for small devices, but in recent years, they have also been used as power sources for hybrid vehicles and electric vehicles. It is attracting attention.

  In the lithium ion secondary battery, as the performance of the device increases, the energy density is increasing, and it is important to ensure the reliability. In addition, in a medium-sized or large-sized lithium ion secondary battery such as an in-vehicle power supply, it is necessary to ensure reliability particularly compared to a small device. Furthermore, as a vehicle-mounted power source, a lithium ion secondary battery capable of maintaining a charge / discharge capacity for a long period is required in accordance with a product cycle.

  In the lithium ion secondary battery, charging and discharging are performed by moving lithium (Li) ions between the positive electrode and the negative electrode. At this time, if the acceptability of Li ions at the negative electrode is poor, Li dendrite is generated on the surface of the negative electrode, and the battery deteriorates rapidly. Moreover, Li dendrite may break through the separator and short-circuit, and in the worst case, it will ignite. The fact that the acceptability of Li ions is poor means that the number of Li ions diffusing is larger than the number of Li ions to be intercalated in the negative electrode. For example, when charging at a high rate, or when the capacity of the negative electrode is insufficient with respect to the capacity of the positive electrode, Li dendrite is likely to occur. Under such circumstances, in a lithium ion secondary battery, it is common to provide restrictions on charging and discharging at a high rate, and to design a larger capacity of the negative electrode than the capacity of the positive electrode.

  In order to improve the acceptability of Li ions in the negative electrode, attempts have been made to sufficiently contact the negative electrode active material and the electrolytic solution or to reduce the concentration distribution of Li ions (for example, Patent Documents 1 and 2). .

In Patent Document 1, attention is paid to the density of the negative electrode mixture, and when the density of the mixture of graphite particles and organic binder exceeds 1.9 g / cm ³ , the quick charge characteristics are reduced to 1.5 g / cm 2. It is stated that the energy density per volume of the obtained lithium ion secondary battery becomes smaller at less than m ³ . By adjusting the negative electrode mixture density within an appropriate range described in Patent Document 1, rapid charge characteristics can be obtained. That is, the acceptability of Li ions can be improved.
Patent Document 2 focuses on the concentration distribution of Li ions in the separator, and local Li dendrite growth is a separator having random vacancies with respect to a non-uniform lithium reaction layer due to current distribution. It is said that the current distribution of non-uniform lithium ions due to the reaction is considered to be caused by the reaction, and a separator made of a porous resin film having pores arranged three-dimensionally is proposed.
However, the electrolyte solution at the negative electrode-separator interface is constrained in narrow concave holes, and concentration diffusion in the in-plane direction is not sufficiently performed. That is, it is difficult to eliminate variations in the Li ion concentration inside each hole nearest to the negative electrode, and the negative electrode described in Patent Document 1 or the separator described in Patent Document 2 has a uniform concentration distribution of Li ions on the negative electrode surface. It is hard to say that it is not enough to make it.

Japanese Patent Laid-Open No. 10-188959 JP 2011-60539 A

  In view of the above circumstances, the structure of the known separator is not sufficient as a structure for preventing Li dendrite. Accordingly, an object of the present invention is to provide a porous film having a structure in which Li dendrite hardly occurs, and to provide a lithium ion secondary battery with improved life characteristics.

  The inventors have found an efficient structure capable of suppressing Li dendrite by appropriately controlling the surface structure of the porous film, and using the porous film having the structure of the present invention as a separator, The present inventors have found that a lithium ion secondary battery capable of significantly improving characteristics and improving safety can be realized, and have completed the present invention.

That is, the present invention is as follows.
[1]
A porous film having a concave or convex pattern on at least one surface, and the length (L) of the major axis of the concave or convex pattern being 0.5 μm or more and 100 μm or less.
[2]
The porous film according to [1], wherein the concave or convex pattern is different from a pattern of pores inside the porous film.
[3]
The porous film according to [1] or [2], wherein a pattern pitch (P) of the concave or convex pattern is 1 μm or more and 110 μm or less.
[4]
The porous film according to any one of [1] to [3], wherein a height of the concave or convex pattern is 25 μm or less.
[5]
The porous film according to any one of [1] to [4], wherein the total film thickness of the porous film including the height of the concave or convex pattern is 25 μm or less.
[6]
L / P, which is a ratio of the length (L) of the major axis of the concave or convex pattern to the pattern pitch (P) of the pattern, is 0.01 or more and 0.9 or less, [1] to [1] [5] The porous film according to any one of [5].
[7]
The concave or convex pattern has at least one surface, the length (L) of the major axis of the concave or convex pattern exceeds 100 μm, and the width of the concave or convex pattern (L _W ) is 0 A porous film having a thickness of 5 μm or more and 100 μm or less.
[8]
The porous film according to [7], wherein the concave or convex pattern is different from a pattern of pores inside the porous film.
[9]
The porous film according to [7] or [8], wherein a pattern pitch (P) of the concave or convex pattern exceeds 110 μm.
[10]
The porous film according to any one of [7] to [9], wherein a height of the concave or convex pattern is 25 μm or less.
[11]
The porous film according to any one of [7] to [10], wherein the total film thickness of the porous film including the height of the concave or convex pattern is 25 μm or less.
[12]
[7] to [7], wherein L / P, which is the ratio of the length (L) of the major axis of the concave or convex pattern to the pattern pitch (P) of the pattern, is 0.01 or more and 0.9 or less. [11] The porous film according to any one of [11].
[13]
L _W / P _W which is the ratio of the width (L _W ) of the concave or convex pattern to the pattern pitch (P _W ) in the direction perpendicular to the concave or convex pattern pitch (L) is 0.01 The porous film according to any one of [7] to [12], which is 1.0 or more and 1.0 or less.
[14]
The porous film is composed of a porous layer containing polyolefin as a main component and a porous layer containing inorganic particles and / or organic particles as a main component, and at least one surface of the porous layer containing the polyolefin as a main component. The porous film according to any one of [1] to [13], wherein the concave or convex pattern is present.
[15]
The porous film comprises a porous layer containing polyolefin as a main component and a porous layer containing inorganic particles and / or organic particles as a main component, and includes the inorganic particles and / or organic particles as a main component. The porous film according to any one of [1] to [13], wherein the concave or convex pattern is on at least one surface of the porous layer.
[16]
The length of the major axis of the concave or convex pattern is the diameter of a circle with the smallest area including the concave or convex pattern on the inside, according to any one of [1] to [13]. Porous film.
[17]
The porous film according to [16], wherein the circle is in contact with the concave or convex pattern at at least two points.
[18]
Lithium ion secondary containing a positive electrode, a laminate in which the porous film according to any one of [1] to [17] and a negative electrode are laminated, or a wound body of the laminate, and a nonaqueous electrolyte battery.
[19]
The lithium ion secondary battery according to [18], wherein a surface having the concave or convex pattern of the porous film faces the negative electrode side.

  According to the present invention, it is possible to provide a nonaqueous electrolyte battery such as a lithium ion secondary battery that is excellent in both life characteristics and safety.

It is a schematic diagram which shows the pattern area | region in the 1st surface of the porous film which concerns on one Embodiment of this invention. It is the schematic diagram projected from the direction perpendicular | vertical to the main surface which shows the pattern area | region of the porous film which concerns on one Embodiment of this invention. It is a schematic diagram which shows the cone shape which is an example of the pattern area | region in the 1st surface of the porous film which concerns on one Embodiment of this invention. It is a figure explaining the length (L) of the long axis of a pattern. It is a figure explaining the width | variety ( _LW ) of the pattern.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

One embodiment of the present invention is a porous film, and at least one surface of the porous film has a concave or convex pattern, and the length of the major axis of the concave or convex pattern is 0.5 μm or more and 100 μm or less. It is. The concave or convex pattern has a long axis length of a micrometer unit and is also called a fine pattern.
[Fine pattern]
In the present embodiment, as shown in FIG. 1, a pattern region 11 having a plurality of convex portions 11a and concave portions 11b, that is, patterns (uneven structure) is formed on at least the first surface of the porous film. The pattern may be formed on the entire main surface or a part of the main surface. In the present specification, the “main surface” means a surface having at least three sides and having a maximum area among the surfaces of the porous film, or an electrode or a negative electrode when incorporated in a nonaqueous electrolyte battery. It means the opposite surface. It is preferable that there is a pattern on the entire surface from the viewpoint of uniform diffusion of Li ions. Different patterns may be divided in the plane as necessary. Moreover, you may give a pattern to a 2nd surface as needed, and the pattern of a 1st surface and a 2nd surface may be the same, and may differ.

  The pattern in the pattern region 11 may be formed by directly processing the porous film substrate 10 or may be formed by adding an arbitrary material to the porous film substrate 10. In particular, even in a printing method in which a surface is formed with another material such as screen printing or ink jet printing, or direct application of unevenness by flat plate shape transfer such as calendering or imprinting with a pattern-added roll. Good.

  The length (L) of the long axis of the pattern in the pattern region 11 is preferably 0.5 μm or more and 100 μm or less. The lower limit is more preferably 1 μm or more, and further preferably 2 μm or more. By this lower limit, it is possible to exert a resistance against the pressure applied between the positive electrode and the negative electrode, and it becomes possible to keep the porous film parallel, make the distance between the negative electrode and the positive electrode uniform, and reduce the reaction distribution. be able to. The upper limit is more preferably 80 μm or less, further preferably 50 μm or less, and still more preferably 30 μm or less. By setting this upper limit on the length of the long axis of the pattern, the contact area between the porous film and the negative electrode can be further reduced, the increase in resistance due to contact of the porous film can be suppressed, and the generation of Li dendrite can be suppressed. it can. The length of the short axis of the pattern is not particularly limited as long as it is shorter than the length of the long axis of the pattern.

  The length (L) of the major axis of the concave or convex pattern is the minimum including the pattern inside when the pattern is observed from a direction perpendicular to the patterning surface of the porous film (generally in the thickness direction of the film). The diameter of the area circle. Preferably, the pattern and the circle meet at at least two points. For example, when the outline of the pattern is a pentagon, the diameter of the circle with the smallest area including the pattern inside is as shown in FIG. A circle drawn with a dotted line in FIG. 4 is a circle with the smallest area including the pattern inside. The diameter of this circle is the length (L) of the long axis of the pattern.

  All the heights of the patterns may be prepared, or several kinds of heights may be mixed. That is, the height histogram may be multistage or continuous. From the viewpoint of making the distance between the negative electrode and the positive electrode uniform and reducing the reaction distribution, the height is preferably three or less, more preferably two or less, more preferably all the heights are uniform. Is preferred. However, the variation is allowed from the viewpoint of manufacturing. The height of the pattern here refers to the distance from the imaginary plane constituted by the lowest part in the thickness direction of the porous film to the most advanced part of the pattern.

  The height of the pattern is preferably 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less, more preferably 8 μm or less, from the viewpoint of battery characteristics or safety of a nonaqueous electrolyte battery including a porous film as a separator. , 7 μm or less, 6 μm or less, or 5 μm or less.

  The concave or convex pattern pitch (P) is preferably 1 μm or more and 110 μm or less. The pattern pitch is more preferably 2 μm or more, and further preferably 3 μm or more. When the pattern pitch is equal to or greater than this lower limit, the contact area between the porous film and the negative electrode can be further reduced, an increase in resistance due to the contact of the porous film can be suppressed, and the occurrence of Li dendrite can be suppressed. The upper limit is preferably 110 μm or less, more preferably 90 μm or less, and still more preferably 80 μm or less. When the pattern pitch is below this upper limit, it is possible to exert a resistance against the pressure applied between the positive electrode and the negative electrode, and to maintain the porous film in parallel, the distance between the negative electrode and the positive electrode. Can be made uniform and the reaction distribution can be reduced. The pattern pitch here is defined by the distance between the center of a circle with the smallest area including a certain pattern on the inside and the center of the circle with the smallest area including another pattern on the inner side.

  When the length of the major axis of the pattern is L and the pattern pitch is P, the ratio L / P is preferably 0.01 or more and 0.9 or less. The lower limit is more preferably 0.05 or more, and still more preferably 0.10 or more. By setting this lower limit to L / P, it is possible to exert a resistance against the pressure applied between the positive electrode and the negative electrode, and to keep the porous film in parallel. It can be made uniform and the reaction distribution can be reduced. Moreover, the upper limit is more preferably 0.85 or less, and further preferably 0.80 or less. By being below this upper limit, the contact area of a porous film and a negative electrode can be reduced more, the raise of resistance by a porous film contacting can be suppressed, and generation | occurrence | production of Li dendrite can be suppressed.

When the length (L) of the major axis of the pattern in the pattern region 11 exceeds 100 μm, the width (L _W ) of the concave or convex pattern is preferably 0.5 μm or more and 100 μm or less. The lower limit is more preferably 1 μm or more, and further preferably 2 μm or more. By this lower limit, it is possible to exert a resistance against the pressure applied between the positive electrode and the negative electrode, and it becomes possible to keep the porous film parallel, make the distance between the negative electrode and the positive electrode uniform, and reduce the reaction distribution. be able to. The upper limit is more preferably 80 μm or less, further preferably 50 μm or less, and still more preferably 30 μm or less. By setting this upper limit on the length of the long axis of the pattern, the contact area between the porous film and the negative electrode can be further reduced, the increase in resistance due to contact of the porous film can be suppressed, and the generation of Li dendrite can be suppressed. it can. The width (L _W ) of the pattern here is a rectangular short of the minimum area including the pattern inside when the pattern is observed from a direction perpendicular to the patterning surface of the porous film (generally in the film thickness direction). The length of the side.
For example, when the contour of the pattern is an ellipse and the length (L) of the major axis of the pattern, that is, the diameter of the circle with the smallest area including the pattern inside exceeds 100 μm, the width of the pattern (L _W ) is as shown in FIG. become that way. A rectangle drawn with a dotted line in FIG. 5 is a rectangle with the smallest area including the pattern inside. The short side of the child rectangle is the pattern width (L _W ).

  When the length (L) of the major axis of the pattern in the pattern region 11 exceeds 100 μm, the concave or convex pattern pitch (P) preferably exceeds 110 μm. The lower limit is preferably more than 120 μm, more preferably more than 150 μm.

  When the length (L) of the major axis of the pattern in the pattern region 11 exceeds 100 μm, when the length of the major axis of the pattern is L and the pattern pitch is P, the ratio L / P is 0.01. It is preferable that it is 1.0 or more. The lower limit is more preferably 0.05 or more, and still more preferably 0.10 or more. By setting this lower limit to L / P, it is possible to exert a resistance against the pressure applied between the positive electrode and the negative electrode, and to keep the porous film in parallel. It can be made uniform and the reaction distribution can be reduced. Further, the upper limit is more preferably 0.95 or less, and still more preferably 0.90 or less. By being below this upper limit, the contact area of a porous film and a negative electrode can be reduced more, the raise of resistance by a porous film contacting can be suppressed, and generation | occurrence | production of Li dendrite can be suppressed.

When the length (L) of the long axis of the pattern in the pattern region 11 exceeds 100 μm, the ratio L _W / which is the ratio when the pattern width L _W and the pattern pitch in the direction perpendicular to the pattern pitch is P _W P _W is preferably 0.01 or more and 0.9 or less. The lower limit is more preferably 0.05 or more, and still more preferably 0.10 or more. By setting this lower limit to L / P, it is possible to exert a resistance against the pressure applied between the positive electrode and the negative electrode, and to keep the porous film in parallel. It can be made uniform and the reaction distribution can be reduced. Further, the upper limit is more preferably 0.85 or less, and still more preferably 0.85 or less. By being below this upper limit, the contact area of a porous film and a negative electrode can be reduced more, the raise of resistance by a porous film contacting can be suppressed, and generation | occurrence | production of Li dendrite can be suppressed.

  As shown in FIG. 2, the surface of the pattern region 11 preferably has a lattice shape (for example, a tetragonal arrangement or a hexagonal arrangement), a line-and-space structure, or the like, and a plurality of these structures may be included. In addition, the uneven shape of the cross section may be a rectangle, a square, a trapezoid, a rhombus, a hexagon, a triangle, a circle, a shape having a curvature (for example, a cone shape as shown in FIG. 3), or the like. Further, even if a part of the pattern is missing, it can be considered that the pattern is included if it can be determined that it is caused by a missing part at the time of production in the production line scale. Further, regarding periodic omission, if it can be recognized as a combination of pattern types, it can be regarded as including a pattern.

  The concave or convex pattern is preferably different from the pattern of pores inside the porous film. In the present specification, the pattern of pores inside the porous film means a projected pattern obtained by projecting the pores onto the patterned surface from a direction perpendicular to the patterned surface of the porous film. By making the concave or convex pattern different from the pattern of pores inside the porous film, the electrolyte flow is disturbed and stirring occurs when the porous film is placed in the nonaqueous electrolyte battery. Thus, the Li concentration can be made uniform, the local reaction can be suppressed, and the generation of Li dendrite can be suppressed.

[Porous film]
In the present embodiment, the porous film only needs to have a high ion permeability and a function of electrically isolating the positive electrode and the negative electrode. The conventionally well-known porous film used for a nonaqueous electrolyte battery can be used, and it does not restrict | limit in particular.

Specifically, it is stable against non-aqueous electrolytes in batteries, such as polyolefins (eg, polyethylene (PE), polypropylene (PP), etc.), polyesters, polyimides, polyamides, polyurethanes, and the like. A microporous film or a nonwoven fabric made of a stable material can be used as the porous film.
The porous film preferably has a property that its pores are blocked at a temperature of 80 ° C. or higher (more preferably 100 ° C. or higher) and preferably 180 ° C. or lower (more preferably 150 ° C. or lower) (ie, a shutdown function). ) Is preferable. Therefore, the porous film preferably has a melting temperature, that is, a melting temperature range measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121, preferably 80 ° C. or more (more preferably 100 ° C. As described above, it is more preferable to use a microporous film or a nonwoven fabric containing polyolefin that is preferably 180 ° C. or lower (more preferably 150 ° C. or lower). In this case, the microporous film or non-woven fabric that becomes the porous film may be formed of, for example, only PE or PP, and may further include two or more kinds of materials. The porous film may be a laminate of a PE microporous membrane and a PP microporous membrane (for example, a PP / PE / PP three-layer laminate).
The viscosity average molecular weight (Mv) of the polymer resin constituting the porous film is preferably 10,000 to 1,000,000 from the viewpoint of expressing the desired shutdown performance of the porous film.

  As the above-mentioned microporous membrane, for example, an ion-permeable porous membrane having many holes formed by a conventionally known solvent extraction method, dry type or wet drawing method (separator for non-aqueous electrolyte battery) Can be used.

  When organic particles such as inorganic particles or resin fine particles are contained in the porous film, a separator having a single layer structure is formed by containing inorganic particles and / or resin fine particles in the microporous film or non-woven fabric. In addition to using the above-mentioned microporous membrane or nonwoven fabric as a base material, a porous layer containing battery inorganic particles and / or resin fine particles as a main component is disposed on one side or both sides of the base material. A separator can also be formed. In this specification, unless specifically indicated otherwise, including a specific component as a main component in a layer or film means including 50% by mass or more of the component with respect to the mass of the layer or film.

The inorganic particles are preferably sodium oxide, potassium oxide, magnesium oxide, calcium oxide, barium oxide, lanthanum oxide, cerium oxide, strontium oxide, vanadium oxide, SiO ₂ —MgO (magnesium silicate), SiO ₂ —CaO (silica). Calcium acid), hydrotalcite, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lanthanum carbonate, cerium carbonate, basic titanate, basic silicotitanate, basic copper acetate, basic lead sulfate , Layered double hydroxide (Mg-Al type, Mg-Fe type, Ni-Fe type, Li-Al type), layered double hydroxide-alumina silica gel composite, boehmite, alumina, zinc oxide, lead oxide, oxidation Iron, iron oxyhydroxide, hematite, bismuth oxide, oxidation Anion adsorbents such as tin, titanium oxide, zirconium oxide, cation adsorbents such as zirconium phosphate, titanium phosphate, apatite, non-basic titanate, niobate, niobium titanate, zeolite, sulfuric acid Carbonates and sulfates such as calcium, magnesium sulfate, aluminum sulfate, gypsum, barium sulfate, alumina trihydrate (ATH), fumed silica, precipitated silica, zirconia, and oxide ceramics such as yttria, silicon nitride, Nitride ceramics such as titanium nitride and boron nitride, layered silicates such as silicon carbide, talc, dickite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, amethite, bentonite, asbestos, diatomaceous earth, glass fiber , Synthetic layered Kate, for example, may be at least one inorganic particles selected from the group consisting of mica or fluoro mica, and zinc borate.

  In addition, the resin fine particles are composed of an electrochemically stable resin that has heat resistance and electrical insulation, is stable with respect to the non-aqueous electrolyte in the battery, and is not easily oxidized or reduced in the operating voltage range of the battery. It is preferred that Examples of the resin for forming such resin fine particles include styrene resin (polystyrene and the like), styrene butadiene rubber, acrylic resin (polymethyl methacrylate and the like), polyalkylene oxide (polyethylene oxide and the like), and fluororesin (polyvinylidene fluoride and the like). And a crosslinked product of at least one resin selected from the group consisting of these derivatives, urea resins, and polyurethanes. As the resin fine particles, the resins exemplified above may be used alone or in combination of two or more. Moreover, the resin fine particles may contain a known additive that can be added to the resin, for example, an antioxidant, if necessary.

  The form of the inorganic particles or resin fine particles may be any form such as plate, scale, needle, column, sphere, polyhedron, and block. The inorganic particles or resin fine particles having the above form may be used alone or in combination of two or more. From the viewpoint of improving permeability, a polyhedral shape having a plurality of surfaces is preferable.

  The average particle diameter (D50) of the inorganic particles or resin fine particles is preferably 0.1 μm to 4.0 μm, more preferably 0.2 μm to 3.5 μm, and 0 More preferably, it is 4 μm to 3.0 μm. By adjusting the average particle diameter within such a range, thermal shrinkage at a high temperature tends to be further suppressed.

  In addition, for the porous film having the above multilayer structure, in order to ensure a shutdown function when used as a separator, the above-mentioned base material includes a microporous film or a nonwoven fabric mainly containing a polyolefin having the above melting temperature. It is preferable that the microporous membrane contains a polyolefin having the above melting temperature as a main component. That is, a separator having a multilayer structure has a porous layer containing organic particles such as inorganic particles and / or resin fine particles as a main component, and a porous layer containing a polyolefin having the above melting temperature as a main component. It is particularly preferable.

  In the porous film having the multilayer structure described above, the microporous film or nonwoven fabric serving as the substrate and the porous layer containing organic particles such as inorganic particles and / or resin fine particles may be integrated. , Each is an independent film, and may be stacked in the battery to form a separator.

  In a separator having a multilayer structure having a porous layer containing organic particles such as inorganic particles and / or resin fine particles as a main component and a porous layer containing a polyolefin having the above melting temperature as a main component, polyolefin is the main component. In the porous layer included as a component, the content of polyolefin in the total volume of the constituent components (total volume excluding voids) is preferably 30% by volume or more, more preferably 50% by volume or more. It is preferably 100% by volume or less.

  Regarding a separator having a multilayer structure having a porous layer containing organic particles such as inorganic particles and / or resin fine particles as a main component and a porous layer containing a polyolefin having the above melting temperature as a main component, a polyolefin The porous layer (especially the microporous membrane) containing as a main component easily undergoes thermal shrinkage due to the high temperature inside the battery. However, in the separator having the multilayer structure described above, the porous layer containing inorganic particles and / or organic particles for nonaqueous electrolyte batteries that hardly undergo heat shrinkage acts as a heat-resistant layer, and heat shrinkage of the entire separator is suppressed. Therefore, it is possible to achieve a nonaqueous electrolyte battery that is superior in safety at higher temperatures.

  When the porous film having the above multilayer structure is used as a separator, the layer containing organic particles such as inorganic particles and / or resin fine particles is bonded to the particles, or the inorganic particles and / or the resin. In order to bind the layer containing fine particles and the substrate (the above-mentioned nonwoven fabric or microporous film), it is preferable to contain a binder.

  Although it does not specifically limit as said binder, For example, it is at least 1 selected from the group which consists of the particle | grains of a nonelectroconductive polymer and the polymer which has a core shell structure.

The particles of the non-conductive polymer or the polymer having a core-shell structure include resins roughly classified into the following (b1) to (b4):
(B1) Nitrile resin (b2) Acrylic resin (b3) Aliphatic conjugated diene resin (b4) Resins different from (b1) to (b3) above

(B1) Nitrile Resin A nitrile resin is a resin containing a polymer unit having a nitrile group as a main component. In this specification, including a polymerization unit as a main component means that it is 50 mol% or more based on the total mol of all monomers charged at the time of polymerization. The nitrile resin may optionally contain, in addition to the polymer unit having a nitrile group, an ethylenically unsaturated compound, a linear alkylene polymer unit having 4 or more carbon atoms, a polymer unit having a hydrophilic group, or a polymer unit having a reactive group. , Aromatic vinyl polymerized units, and at least one selected from the group consisting of polymerized units having a thermally crosslinkable group. Examples of the thermally crosslinkable group include an epoxy group, an N-methylolamide group, an oxazoline group, and an allyl group. In the case of having a thermally crosslinkable group, the abundance of the monomer unit having a thermally crosslinkable group in the nitrile resin is the total amount of the (meth) acrylonitrile monomer unit and the (meth) acrylic acid ester monomer unit. 0.01 mass part or more and 4 mass parts or less are preferable with respect to 100 mass parts.

  The iodine value of the nitrile resin is preferably 3 to 60 mg / 100 mg, more preferably 3 to 30 mg / 100 mg, and even more preferably 3 to 10 mg / 100 mg.

  The nitrile resin can be obtained by polymerization of a monomer having a nitrile group, or copolymerization of a monomer having a nitrile group and another monomer. Examples of the monomer having a nitrile group include (meth) acrylonitrile. (Meth) acrylonitrile means acrylonitrile or methacrylonitrile.

  Other monomers include ethylenically unsaturated compounds such as acrylic acid, 2-methacrylic acid, 2-pentenoic acid, 2,3-dimethylacrylic acid, 3,3-dimethylacrylic acid, itaconic acid, and the like (Meth) acrylic acid such as alkali metal salts of The (meth) acrylic acid ester means an acrylic acid ester or a methacrylic acid ester. In the (meth) acrylic acid ester monomer, a part or all of the hydrogen of the alkyl group is substituted with a halogen such as fluorine. It may be a group. Carbon number of the alkyl group couple | bonded with the non-carbonyl-type oxygen atom of (meth) acrylic-acid alkylester becomes like this. Preferably it is 1-14, More preferably, it is 1-5.

  Examples of the alkyl (meth) acrylate alkyl ester having 1 to 5 carbon atoms bonded to a non-carbonyl oxygen atom include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and acrylic acid n. Acrylic acid alkyl esters such as butyl, t-butyl acrylate, hexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate; 2 such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane triacrylate Carboxylic acid esters having one or more carbon-carbon double bonds.

  Other (meth) acrylic acid alkyl esters include non-carbonyl oxygen such as n-hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, and isobornyl acrylate. Acrylic acid alkyl ester having 6 to 18 carbon atoms in the alkyl group bonded to the atom; n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, methacrylic acid Stearyl and methacrylic acid alkyl ester having 6 to 18 carbon atoms bonded to non-carbonyl oxygen atom such as cyclohexyl methacrylate; 2- (perfluorohexyl) acrylate Chill, 2- (perfluorooctyl) ethyl acrylate, 2- (perfluorononyl) ethyl acrylate, 2- (perfluorodecyl) ethyl acrylate, 2- (perfluorododecyl) ethyl acrylate, 2-acrylic acid 2- Acrylic acid 2- (perfluoroalkyl) having 6 to 18 carbon atoms in the alkyl group bonded to a non-carbonyl oxygen atom such as (perfluorotetradecyl) ethyl and 2- (perfluorohexadecyl) ethyl acrylate Ethyl; 2- (perfluorohexyl) ethyl methacrylate, 2- (perfluorooctyl) ethyl methacrylate, 2- (perfluorononyl) ethyl methacrylate, 2- (perfluorodecyl) ethyl methacrylate, 2-methacrylic acid 2- (Perfluorododecyl) ethyl, methacrylic acid 2- (per 2- (perfluoroalkyl) ethyl methacrylate having 6 to 18 carbon atoms in the alkyl group bonded to a non-carbonyl oxygen atom such as trifluorotetradecyl) ethyl and 2- (perfluorohexadecyl) ethyl methacrylate ;

  Examples of the linear alkylene polymer unit having 4 or more carbon atoms include butadiene, isoprene, and pentadiene.

  The hydrophilic group refers to a functional group that liberates protons in an aqueous solvent, and a salt in which the proton is replaced with a cation. Specifically, a carboxylic acid group, a sulfonic acid group, a hydroxyl group, a phosphoric acid group, and These salts are mentioned. The content ratio of the hydrophilic group is preferably in the range of 0.05 to 10% by mass.

  Introduction of the hydrophilic group into the nitrile resin is performed by polymerizing a monomer containing a carboxylic acid group, a sulfonic acid group, a hydroxyl group, a phosphoric acid group, and a metal salt or ammonium salt thereof.

  Examples of the monomer having a carboxylic acid group include monocarboxylic acids and derivatives or dicarboxylic acids thereof, and derivatives thereof. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, 3-butenoic acid, and crotonic acid. Monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, β-diaminoacrylic acid, trans -Butenedionic acid, cis-butenedionic acid, etc. are mentioned. Examples of the dicarboxylic acid include maleic acid, fumaric acid, and itaconic acid. Examples of the dicarboxylic acid derivative include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, and fluoromaleic acid. Furthermore, methylallyl maleate, diphenyl maleate, nonyl maleate, maleate And maleate esters such as decyl acid, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate. Moreover, the acid anhydride which produces | generates a carboxyl group by hydrolysis can also be used. Examples of the acid anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride.

  Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, ethyl (meth) acrylic acid-2-sulfonate, 2-acrylamido-2-methylpropane sulfone. Acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

Examples of the monomer having a hydroxyl group include ethylenically unsaturated alcohols such as (meth) allyl alcohol, 3-buten-1-ol, and 5-hexen-1-ol; acrylate-2-hydroxyethyl, acrylate-2- Ethylene such as hydroxypropyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, and di-2-hydroxypropyl itaconate alkanol esters of unsaturated carboxylic acids; formula _{CH 2 = CR 1 -COO - (} (CH 2) n O) m -H { wherein, m is 2-9 integer, n represents an integer of 2 to 4, R ₁ of the esters of a polyalkylene glycol and (meth) acrylic acid represented by} represents hydrogen or methyl group; Mono (meth) acrylic acid esters of dihydroxy esters of dicarboxylic acids such as -hydroxyethyl-2 '-(meth) acryloyloxyphthalate, 2-hydroxyethyl-2'-(meth) acryloyloxysuccinate; Vinyl ethers such as vinyl ether and 2-hydroxypropyl vinyl ether; (meth) allyl-2-hydroxyethyl ether, (meth) allyl-2-hydroxypropyl ether, (meth) allyl-3-hydroxypropyl ether, (meth) allyl- Mono- (methyl) alkylene glycols such as 2-hydroxybutyl ether, (meth) allyl-3-hydroxybutyl ether, (meth) allyl-4-hydroxybutyl ether, and (meth) allyl-6-hydroxyhexyl ether. ) Allyl ethers; polyoxyalkylene glycol (meth) monoallyl ethers such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether or glycerin mono (meth) allyl ether; (meth) allyl-2 -Mono (meth) allyl ethers of halogens and hydroxy substituents of (poly) alkylene glycols such as chloro-3-hydroxypropyl ether, (meth) allyl-2-hydroxy-3-chloropropyl ether; eugenol, isoeugenol, etc. Mono (meth) allyl ethers of polyhydric phenols and halogen-substituted products thereof; alkylene glycols such as (meth) allyl-2-hydroxyethylthioether and (meth) allyl-2-hydroxypropylthioether Meth) allyl thioether compound; and the like.

  Examples of the monomer having a phosphoric acid group include phosphoric acid-2- (meth) acryloyloxyethyl phosphate, methyl-2- (meth) acryloyloxyethyl phosphate, and ethyl phosphate- (meth) acryloyloxyethyl phosphate.

The polymerized unit having a reactive group is added to the polymer in order to improve the reactivity with the surface functional groups of the inorganic particles and / or organic particles, or the dispersibility of the inorganic particles and / or organic particles when producing a slurry. May be incorporated. As the polymerization unit having a reactive group, when the surface functional group of inorganic particles and / or organic particles is an amino group, the reactive group of the nitrile resin is preferably an epoxy group, a carbonyl group, or a carboxyl group, and an epoxy group Is more preferable.
Further, when the surface functional group of the inorganic particle and / or organic particle is an epoxy group, the reactive group of the nitrile resin is preferably a sulfonic acid group, an amino group, a phosphoric acid group, a hydroxyl group, a mercapto group, and an isocyanate group. More preferred are a sulfonic acid group and an amino group.
Moreover, when the surface functional group of the inorganic particle and / or organic particle described above is a mercapto group, the reactive group of the nitrile resin is preferably an epoxy group or a mercapto group.
Moreover, when the surface functional group of the inorganic particle and / or organic particle mentioned above is an isocyanate group, an epoxy group and a hydroxyl group are preferable as the reactive group of the nitrile resin.
Moreover, when the surface functional group of the inorganic particle and / or organic particle described above is a hydroxyl group or a carboxyl group, the reactive group is preferably a carbodiimide group, an epoxy group, an oxazoline group, a hydrazide group, or an isocyanato group.

  Furthermore, the nitrile resin is not limited to the above-mentioned repeating units (that is, (meth) acrylonitrile monomer units, (meth) acrylic acid ester monomer units, and monomer units having a thermally crosslinkable group), Any repeating unit may be included. Examples of the monomer corresponding to the above arbitrary repeating unit include styrene, chlorostyrene, vinyl toluene, t-butyl styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, α-methyl styrene. And styrene monomers such as divinylbenzene; olefins such as ethylene and propylene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl butyrate; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; N-vinyl pyrrolidone, vinyl Heterocycle-containing vinyl compounds such as lysine and vinylimidazole; amide monomers such as acrylamide; sulfonate esters such as acrylamide-2-methylpropanesulfonic acid; imino compounds, maleimides, unsaturated polyalkylene glycol ethers Bodies, ethylene functional silicon-containing monomers, chelate compounds, isothiazolines, siloxanes, sulfosuccinates and their salts. The nitrile resin may contain only one type of the above arbitrary repeating unit, or may contain two or more types in combination at an arbitrary ratio. However, from the viewpoint of remarkably exhibiting the advantages of including the (meth) acrylonitrile monomer unit and the (meth) acrylic acid ester monomer unit as described above, the amount of the arbitrary repeating unit is small. Preferably, it does not contain any of the above repeating units.

  The weight average molecular weight of the nitrile resin is preferably 10,000 or more, more preferably 20,000 or more, preferably 2,000,000 or less, more preferably 500,000 or less. When the weight average molecular weight of the nitrile resin is in the above range, the strength of the porous film of the present invention and / or the dispersibility of the organic particles can be easily improved.

  The volume average particle diameter D50 of the nitrile resin is preferably 0.01 μm or more, preferably 0.5 μm or less, and more preferably 0.2 μm or less. By setting the volume average particle diameter D50 of the nitrile resin to be equal to or greater than the lower limit of the above range, the porosity of the porous film of the present invention is kept high, the resistance of the porous film is suppressed, and the battery physical properties are kept good. Moreover, by making it below the upper limit of the said range, the adhesive point of a nonelectroconductive particle and a water-insoluble particulate polymer can be increased, and binding property can be made high.

  The glass transition temperature (Tg) of the nitrile resin is preferably 20 ° C. or less, more preferably 15 ° C. or less, and particularly preferably 5 ° C. or less. When the glass transition temperature (Tg) is in the above range, the flexibility of the porous film of the present invention is improved, the bending resistance of the electrode and the separator is improved, and the inorganic particles and / or resin fine particles of the present invention are contained. The defect rate due to cracking of the layer to be broken can be reduced. Moreover, a crack, a chip | tip, etc. can also be suppressed at the time of winding the porous film and electrode which have a layer containing the inorganic particle and / or resin fine particle of this invention, and a roll at the time of winding. In addition, the glass transition temperature of a nonelectroconductive polymer can be adjusted by combining various monomers. The lower limit of the glass transition temperature of the nitrile resin is not particularly limited, but can be −50 ° C. or higher.

  In the production process of the nitrile resin, the dispersant used in the polymerization method may be one used in ordinary synthesis. Specific examples include benzenesulfonic acid such as sodium dodecylbenzenesulfonate and sodium dodecylphenylethersulfonate. Alkyl sulfates such as sodium lauryl sulfate and sodium tetradodecyl sulfate; sulfosuccinates such as sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate; fatty acid salts such as sodium laurate; polyoxyethylene lauryl ether sulfate sodium salt, polyoxy Ethoxysulfate salts such as ethylene nonylphenyl ether sulfate sodium salt; alkane sulfonate salt; alkyl ether phosphate sodium salt; polyoxyethylene salt Nonionic emulsifiers such as ruphenyl ether, polyoxyethylene sorbitan lauryl ester, and polyoxyethylene-polyoxypropylene block copolymer; gelatin, maleic anhydride-styrene copolymer, polyvinyl pyrrolidone, sodium polyacrylate, and Examples thereof include water-soluble polymers such as polyvinyl alcohol having a polymerization degree of 700 or more and a saponification degree of 75% or more, and these may be used alone or in combination of two or more. Among these, benzenesulfonates such as sodium dodecylbenzenesulfonate and sodium dodecylphenylethersulfonate; alkyl sulfates such as sodium lauryl sulfate and sodium tetradodecylsulfate are preferable, and oxidation resistance is more preferable. From this point, it is a benzenesulfonate such as sodium dodecylbenzenesulfonate and sodium dodecylphenylethersulfonate. The addition amount of a dispersing agent can be set arbitrarily, and is about 0.01-10 mass parts normally with respect to 100 mass parts of monomer total amounts.

  The pH when the nitrile resin is dispersed in the dispersion medium is preferably 5 to 13, more preferably 5 to 12, and most preferably 10 to 12. When the pH of the nitrile resin is within the above range, the storage stability of the nitrile resin is improved, and further, the mechanical stability is improved.

  The pH adjuster for adjusting the pH of the nitrile resin includes alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, group 2 element oxides such as magnesium hydroxide, calcium hydroxide, and Alkali earth metal oxides such as barium hydroxide, hydroxides such as hydroxides of metals belonging to Group IIIA in the long periodic table such as aluminum hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate, carbonic acid Examples of organic amines include alkyl amines such as ethylamine, diethylamine, and propylamine; monomethanolamine, monoethanolamine, monopropanolamine, and the like. Alcoholamines; ammonia such as ammonia water; It is. Among these, alkali metal hydroxides are preferable from the viewpoint of binding properties or operability, and sodium hydroxide, potassium hydroxide, and lithium hydroxide are particularly preferable.

  The nitrile resin may contain a crosslinking agent. Examples of the crosslinking agent include carbodiimide compounds, polyfunctional epoxy compounds, oxazoline compounds, polyfunctional hydrazide compounds, isocyanate compounds, melamine compounds, urea compounds, and mixtures thereof.

  Specifically, the nitrile resin may be polyacrylonitrile, acrylonitrile-butadiene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-acrylate copolymer, or hydrogenation thereof. Things.

(B2) Acrylic resin An acrylic resin is a resin obtained by using an acrylic compound as a main monomer. Using as a main monomer means that it is 50 mol% or more with respect to the total mol of all monomers charged at the time of superposition | polymerization. The acrylic compound is a monomer having a (meth) acryloyl group which is an acryloyl group or a methacryloyl group.

  The acrylic resin may optionally be added to the polymer unit having an acryloyl group, an ethylenically unsaturated compound containing (meth) acrylonitrile, a linear alkylene polymer unit having 4 or more carbon atoms, a polymer unit having a hydrophilic group, a reaction It may contain at least one selected from the group consisting of a polymer unit having a functional group, an aromatic vinyl polymer unit, and a polymer unit having a thermally crosslinkable group. Examples of the thermally crosslinkable group include an epoxy group, an N-methylolamide group, an oxazoline group, and an allyl group. In the case of having a thermally crosslinkable group, the abundance of the monomer unit having a thermally crosslinkable group in the acrylic resin is the total amount of the (meth) acrylonitrile monomer unit and the (meth) acrylic acid ester monomer unit. 0.01 mass part or more and 4 mass parts or less are preferable with respect to 100 mass parts.

  The acrylic resin can be obtained by polymerization of an acrylic compound or copolymerization of an acrylic compound and another monomer.

As the acrylic compound, the following monomers may be used:
Examples of (meth) acrylic acid include acrylic acid, 2-methacrylic acid, 2-pentenoic acid, 2,3-dimethylacrylic acid, 3,3-dimethylacrylic acid, itaconic acid, and alkali metals thereof. Salt; and the like.
Examples of (meth) acrylic acid esters include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl (meth) acrylate, and acrylic acid t. (Meth) acrylic acid alkyl esters such as butyl, hexyl (meth) acrylate, and (meth) acrylic acid-2-ethylhexyl; two or more such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane triacrylate Examples include diacrylate compounds having a carbon-carbon double bond; triacrylate compounds, tetraacrylate compounds, dimethacrylate compounds, and trimethacrylate compounds. In addition, fluorine-containing acrylic acid ester, amide group-containing (meth) acrylic acid or amide group-containing (meth) acrylate; (meth) acryl functional silicon-containing monomer, and the like can also be mentioned.

  Other monomers include ethylenically unsaturated compounds such as (meth) acrylonitrile, (meth) acrylic acid alkyl esters, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, acrylic Acrylic acid alkyl esters such as n-butyl acid, t-butyl acrylate, hexyl (meth) acrylate, and (meth) acrylic acid-2-ethylhexyl; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane triacrylate And carboxylic acid esters having two or more carbon-carbon double bonds.

  Other (meth) acrylic acid alkyl esters include non-carbonyl oxygen such as n-hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, and isobornyl acrylate. Acrylic acid alkyl ester having 6 to 18 carbon atoms in the alkyl group bonded to the atom; n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, methacrylic acid Stearyl and methacrylic acid alkyl ester having 6 to 18 carbon atoms bonded to non-carbonyl oxygen atom such as cyclohexyl methacrylate; 2- (perfluorohexyl) acrylate Chill, 2- (perfluorooctyl) ethyl acrylate, 2- (perfluorononyl) ethyl acrylate, 2- (perfluorodecyl) ethyl acrylate, 2- (perfluorododecyl) ethyl acrylate, 2-acrylic acid 2- Acrylic acid 2- (perfluoroalkyl) having 6 to 18 carbon atoms in the alkyl group bonded to a non-carbonyl oxygen atom such as (perfluorotetradecyl) ethyl and 2- (perfluorohexadecyl) ethyl acrylate Ethyl; 2- (perfluorohexyl) ethyl methacrylate, 2- (perfluorooctyl) ethyl methacrylate, 2- (perfluorononyl) ethyl methacrylate, 2- (perfluorodecyl) ethyl methacrylate, 2-methacrylic acid 2- (Perfluorododecyl) ethyl, methacrylic acid 2- (per 2- (perfluoroalkyl) ethyl methacrylate having 6 to 18 carbon atoms in the alkyl group bonded to a non-carbonyl oxygen atom such as trifluorotetradecyl) ethyl and 2- (perfluorohexadecyl) ethyl methacrylate ;

  Further, the acrylic resin has a repeating unit as described above (that is, a (meth) acrylic monomer unit, a (meth) acrylonitrile monomer unit, a (meth) acrylic acid ester monomer unit, and a single unit having a thermally crosslinkable group. In addition to (mer unit), any other repeating unit may be included. Examples of monomers corresponding to the above arbitrary repeating units include linear alkylene polymer units having 4 or more carbon atoms, monomers having carboxylic acid groups, monomers having sulfonic acid groups, monomers having hydroxyl groups, and phosphoric acid groups. Styrenes such as styrene, chlorostyrene, vinyltoluene, t-butylstyrene, vinylbenzoic acid, vinylbenzoic acid methyl, vinylnaphthalene, chloromethylstyrene, α-methylstyrene, and divinylbenzene Monomers; Olefins such as ethylene and propylene; Halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; Vinyl esters such as vinyl acetate, vinyl propionate, and vinyl butyrate; Methyl vinyl ether, Ethyl vinyl ether, and Butyl Vinyl ethers such as Vier ether Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; heterocycle-containing vinyl compounds such as N-vinyl pyrrolidone, vinyl pyridine, and vinyl imidazole; amides such as acrylamide Monomers, sulfonic acid esters such as acrylamide-2-methylpropanesulfonic acid; imino compounds, maleimides, unsaturated polyalkylene glycol ether monomers, ethylene functional silicon-containing monomers, chelate compounds, isothiazolines, Examples thereof include siloxanes, sulfosuccinic acid esters and salts thereof. The acrylic resin may contain only one type of the above arbitrary repeating unit, or may contain two or more types in combination at an arbitrary ratio. However, from the viewpoint of remarkably exhibiting the advantages of including the (meth) acrylonitrile monomer unit and the (meth) acrylic acid ester monomer unit as described above, the amount of the arbitrary repeating unit is small. Preferably, it does not contain any of the above repeating units.

  The weight average molecular weight of the acrylic resin is preferably 10,000 or more, more preferably 20,000 or more, preferably 2,000,000 or less, more preferably 500,000 or less. When the weight average molecular weight of the acrylic resin is in the above range, the strength of the porous film of the present invention and the dispersibility of the non-conductive polymer are easily improved.

  The volume average particle diameter D50 of the acrylic resin is preferably 0.01 μm or more, preferably 0.5 μm or less, and more preferably 0.2 μm or less. By setting the volume average particle diameter D50 of the acrylic resin to be equal to or greater than the lower limit of the above range, the porous film of the present invention is maintained with high porosity, the resistance of the porous film is suppressed, and the battery physical properties are kept good. In addition, when the amount is not more than the upper limit of the above range, the bonding point between the inorganic particles and / or the organic particles and the water-insoluble particulate polymer can be increased to increase the binding property.

  The glass transition temperature (Tg) of the acrylic resin is preferably 20 ° C. or less, more preferably 15 ° C. or less, and particularly preferably 5 ° C. or less. When the glass transition temperature (Tg) is within the above range, the flexibility of the porous film of the present invention is improved, the bending resistance of the electrode and the porous film is improved, and the porous film of the present invention is cracked. The defective rate due to can be reduced. In addition, cracks, chipping, and the like can be suppressed when the porous film and electrode of the present invention are wound around a roll or wound. In addition, the glass transition temperature of a nonelectroconductive polymer can be adjusted by combining various monomers. Although the minimum of the glass transition temperature of acrylic resin is not specifically limited, It can be -50 degreeC or more.

  In the production process of the acrylic resin, the dispersant used in the polymerization method may be one used in ordinary synthesis.

  5-13 are preferable, as for pH when acrylic resin is disperse | distributing to a dispersion medium, More preferably, it is 5-12, More preferably, it is 10-12. When the pH of the acrylic resin is within the above range, the storage stability of the acrylic resin is improved, and further, the mechanical stability is improved.

  The pH of the acrylic resin may be adjusted with a pH adjuster.

  The acrylic resin may contain a crosslinking agent.

  Specific examples of the acrylic resin include an acrylic soft polymer, an acrylic hard polymer, an acrylic-styrene copolymer, a sulfonated acrylic polymer, or a seed polymer, a hydrogenated product, or a graft product thereof.

  The acrylic resin may be in the form of a non-conductive polymer. The acrylic resin may be water-soluble when formed from an acrylic compound and a silicon-containing monomer. The acrylic resin may contain carboxymethyl cellulose as a thickener.

(B3) Aliphatic conjugated diene resin The aliphatic conjugated diene resin is a resin obtained using an aliphatic monomer having a conjugated diene as a main component. In this specification, using as a main component means that it is 50 mol% or more with respect to the total mol of all the monomers prepared at the time of superposition | polymerization.

  The aliphatic monomer having a conjugated diene is a substituted or unsubstituted chain diene, and may be linear or branched. Specific examples of the aliphatic monomer having a conjugated diene include 1,3-butadiene, 1,3-isoprene, 1,4-dimethyl-1,3-butadiene, 1,2-dimethyl-1,3- Examples thereof include butadiene, 1,3-dimethyl-1,3-butadiene, 1,2,3-trimethyl-1,3-butadiene, 1,3,5-hexatriene, and alloocimene.

  The aliphatic conjugated diene resin can be obtained by polymerization of an aliphatic monomer having a conjugated diene, or copolymerization of an aliphatic monomer having a conjugated diene and another monomer.

  Other monomers include ethylenically unsaturated carboxylic acid, sulfonic acid group-containing monomer, nitrile group-containing monomer, aromatic vinyl monomer, monomer having a thermally crosslinkable group, and aromatic Vinyl compounds and the like may be used.

  Specifically, the aliphatic conjugated diene resin may be a 1,3-butadiene polymer, a diene rubber, a thermoplastic elastomer, or a random copolymer, a block copolymer, a hydride, or an acid-modified product thereof. . The aliphatic conjugated diene resin may contain an anti-aging agent such as a combination of phenol and thioether, or a combination of phenol and phosphite.

(B4) Resins different from resins (b1) to (b3) Resins (b4) different from resins (b1) to (b3) are, for example, olefin-based resins, fluororesins, sulfonic acid group-containing resins, and cellulose-based resins. Resin or the like. The resin (b4) may be in the form of organic polymer particles, graft polymer, polymer latex, silicon-containing polymer, and the like.

  Specifically, the olefin resin is polyethylene, polypropylene, poly-1-butene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, ethylene / propylene / diene copolymer (EPDM), And a homopolymer of an olefin compound such as an ethylene / propylene / styrene copolymer or a copolymer with a monomer copolymerizable therewith.

  Examples of fluororesins include polytetrafluoroethylene, polyvinylidene fluoride, polychlorotrifluoroethylene, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene -Chlorotrifluoroethylene copolymer, vinylidene fluoride rubber, and tetrafluoroethylene-propylene copolymer.

  Examples of the sulfonic acid group-containing resin include sulfonated polymers such as sulfonated polyethersulfone and sulfonated polysulfone.

  Examples of the cellulose resin include a cellulose semisynthetic polymer and a sodium salt or ammonium salt thereof. Cellulosic resin may have a sulfur atom, a cationic group, an acid group, a propargyl group, and the like.

  Examples of the silicon-containing polymer include dimethyl polysiloxane, diphenyl polysiloxane, and dihydroxy polysiloxane.

[Polymer particles having a core-shell structure]
The polymer particles having a core-shell structure have a core part containing a polymer and a shell part containing a polymer. Moreover, it is preferable that resin which has a core-shell structure has a segment which shows compatibility with a nonaqueous electrolyte, and a segment which is not shown. As the polymer of the core part or the shell part, the resins (b1) to (b4) described above can be used.

  For example, polymer particles having a core-shell structure are polymerized in stages by using a polymer monomer that forms the core part and a polymer monomer that forms the shell part, and changing the ratio of these monomers over time. By doing so, it can be manufactured. Specifically, first, polymer monomers forming the core part are polymerized to produce seed polymer particles. This seed polymer particle becomes the core of the particle. Thereafter, in a polymerization system including seed polymer particles, a polymer monomer that forms a shell portion is polymerized. Thereby, since a shell part is formed on the surface of the core part, polymer particles having a core-shell structure are obtained. At this time, if necessary, for example, a reaction medium, a polymerization initiator, a surfactant, or the like may be used.

(Core part)
The core part of the particles generally has a softening start point or decomposition point at 175 ° C. or higher, preferably 220 ° C. or higher, more preferably 225 ° C. or higher. A core portion having a softening start point or a decomposition point in a temperature range of 175 ° C. or higher is less likely to be deformed during the use environment of the secondary battery and heat press, and can prevent the pores of the microporous film from being blocked. Moreover, since it can suppress that the rigidity of a microporous film falls, shrinkage | contraction of a separator can also be suppressed. Therefore, it is possible to stably prevent a short circuit in a high temperature environment. Moreover, although there is no restriction | limiting in the upper limit of the softening start point or decomposition point of a core part, Usually, it is 450 degrees C or less.

A method for measuring the softening start point will be described below.
First, 10 mg of a measurement sample is weighed into an aluminum pan, and an empty aluminum pan is used as a reference in a differential thermal analysis measurement device, and the temperature rise rate is 10 ° C./min between a measurement temperature range of −100 ° C. to 500 ° C. The DSC curve is measured under normal temperature and humidity. During this temperature rising process, the baseline immediately before the endothermic peak of the DSC curve where the differential signal (DDSC) becomes 0.05 mW / min / mg or more and the tangent line of the DSC curve at the first inflection point after the endothermic peak The point of intersection with is the glass transition point (Tg). Further, a temperature 25 ° C. higher than the glass transition point is set as a softening start point.
When the decomposition point is lower than the softening start point of the core part of the nonconductive polymer, the softening start point may not be observed due to decomposition.

A method for measuring the decomposition point will be described below.
Under a nitrogen atmosphere, the measurement sample is heated from 30 ° C. at a rate of temperature increase of 10 ° C./min with a differential thermothermal weight simultaneous measurement apparatus. At this time, the temperature at which the weight loss ratio reaches 10% by mass is defined as the decomposition point.
When both the softening start point and the decomposition point of the core part of the particle are observed, the lower temperature is regarded as the softening start point of the core part.

  As a polymer which forms a core part, the highly crosslinked polymer of resin (b1)-(b4) is mentioned, for example. Since the molecular motion of the polymer is suppressed even at a temperature equal to or higher than the glass transition point of the polymer due to the high degree of crosslinking, the core portion can maintain the shape.

  The polymer forming the core part is preferably obtained by polymerizing a crosslinkable vinyl monomer. Examples of the crosslinkable vinyl monomer include compounds having usually 2 or more, preferably 2 copolymerizable double bonds. Moreover, a crosslinking | crosslinked vinyl monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Suitable crosslinkable vinyl monomers include, for example, non-conjugated divinyl compounds and polyvalent acrylate compounds.

Examples of non-conjugated divinyl compounds include divinylbenzene.
Examples of polyvalent acrylates include polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-hexane glycol diacrylate, neopentyl glycol diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4 -Acryloxypropyloxyphenyl) propane and diacrylate compounds such as 2,2'-bis (4-acryloxydiethoxyphenyl) propane; trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate Triacrylate compounds such as tetramethylol methane tetraacrylate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate , Triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol Dimethacrylate compounds such as dimethacrylate, polypropylene glycol dimethacrylate, and 2,2′-bis (4-methacryloxydiethoxyphenyl) propane; trimethacrylate compounds such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; Can be mentioned.

  The ratio of the crosslinkable vinyl monomer is preferably 20% by mass or more, more preferably 25% by mass or more, and still more preferably 30% by mass or more based on the total monomers of the polymer forming the core part. By adjusting the ratio of the crosslinkable vinyl monomer to 20% by mass or more, the hardness, heat resistance and solvent resistance of the core part can be improved. Moreover, the upper limit of the ratio of a crosslinkable vinyl monomer is 100 mass% or less normally, Preferably it is 98 mass% or less, More preferably, it is 95 mass% or less. Here, the amount of the crosslinkable vinyl monomer is, for example, in terms of a pure product excluding diluent and impurities.

(Shell part)
The softening start point of the shell part of the particles is preferably 85 ° C. or higher, more preferably 87 ° C. or higher, more preferably 89 ° C. or higher, on the other hand, 145 ° C. or lower is more preferable, 125 ° C. or lower is more preferable. 115 ° C. or lower. When the softening start point is 85 ° C. or higher, the blocking resistance of the porous film can be improved. Moreover, since it becomes difficult to melt | dissolve a shell part in the use temperature of a secondary battery, obstruction | occlusion of the hole of a porous film can be suppressed, and, thereby, the rate characteristic of a secondary battery can be improved. In addition, since the softening start point is 145 ° C. or lower, the shell part can be easily melted during heat pressing, thereby improving the adhesion of the porous film, and thereby the cycle characteristics of the secondary battery. Can be improved.

  As the polymer forming the shell part, it is preferable to use a polymer containing a (meth) acrylate unit. By forming the shell portion with a polymer containing a (meth) acrylate unit, the electrical stability of the porous film can be improved. Examples of the acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl ethyl acrylate. Examples of the methacrylate include methyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate.

  From the viewpoint of electrical stability, the ratio of (meth) acrylate units in the polymer forming the shell part is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. It may be 100% by mass or less.

(Size of polymer particles having a core-shell structure)
The number average particle size of the polymer particles having a core-shell structure is preferably 30 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, and on the other hand, 1,500 nm or less is preferable, more preferably 1,200 nm or less. More preferably, it is 1,000 nm or less. By adjusting the number average particle diameter of the particles within such a range, it is possible to form a gap between the particles to such an extent that the particles have contact portions and the movement of ions is not hindered. Therefore, the strength of the microporous film is improved, the short circuit of the battery can be prevented, and the cycle characteristics of the secondary battery can be improved.

  The number average particle diameter of the particles can be measured as follows. 200 particles are arbitrarily selected from a photograph taken at a magnification of 25,000 times with a field emission scanning electron microscope. When the longest side of the particle image is La and the shortest side is Lb, the particle size is (La + Lb) / 2. The average particle size of 200 particles is determined as the average particle size.

  The thickness of the shell part is preferably 3% or more, more preferably 5% or more, still more preferably 7% or more, and preferably 18% or less, more preferably 16% with respect to the number average particle diameter of the particles. % Or less, more preferably 14% or less. When the thickness of the shell part is 3% or more with respect to the number average particle diameter, the adhesiveness of the separator can be enhanced and the cycle characteristics of the secondary battery can be improved. Further, when the thickness of the shell portion is 18% or less with respect to the number average particle diameter, the pore diameter of the separator can be increased to an extent that does not hinder the movement of ions, thereby improving the rate characteristics of the secondary battery. it can. Moreover, since the core part can be relatively enlarged by making the shell part thin, the rigidity of the particles can be increased, so that the rigidity of the microporous film can be increased and the shrinkage of the separator can be suppressed.

The thickness (S) of the shell part is, for example, the number average particle diameter (D1) of the seed polymer particles before forming the shell part and the number average particle diameter (D2) of the non-conductive polymer after forming the shell part. From the following formula:
(D2-D1) / 2 = S
Can be calculated.

(Amount of polymer particles having a core-shell structure)
The content of the polymer particles having a core-shell structure in the porous layer having inorganic particles and / or organic particles is preferably 70% by mass or more, more preferably 75% by mass or more, and further preferably 80% by mass or more. And, 98 mass% or less is preferable, More preferably, it is 96 mass% or less, More preferably, it is 94 mass% or less. When the content ratio of the particles is within the above range, the particles can have gaps between them so that the movement of ions can be prevented while the particles have contact portions, thereby improving the strength of the porous film. The battery short circuit can be stably prevented.

When the porous film contains inorganic particles and / or organic particles, the content of the inorganic particles and / or organic particles in the porous film is, for example, from the viewpoint of favorably ensuring the effect of the use of the porous film. The amount per area is preferably 0.1 g / m ² or more, and more preferably 0.5 g / m ² or more. However, if the content of inorganic particles and / or organic particles in the porous film is too large, the separator becomes thick, which tends to cause a decrease in battery energy density or an increase in internal resistance. Accordingly, the content of inorganic particles and / or organic particles in the porous film is, for example, 15 g / m ² or less, preferably 10 g / m ² or less, in terms of the amount per area of the porous film. More preferred.

  In addition, when the porous film has a porous layer containing inorganic particles and / or organic particles, the total volume of the constituent components of the porous layer of the inorganic particles and / or organic particles in the porous layer (hole portion) The total content excluding) is preferably 1% by volume or more, and more preferably 5% by volume or more and 100% by volume or less from the viewpoint of ensuring a good effect due to its use.

The porosity of the porous film according to the nonaqueous electrolyte battery of the present embodiment is 30% in a dry state of the porous film in order to ensure the amount of nonaqueous electrolyte retained and improve ion permeability. It is preferable that it is above, and it is more preferable that it is 40% or more. On the other hand, from the viewpoint of securing the strength of the porous film and preventing internal short circuit, the porosity of the porous film is preferably 80% or less, and 70% or less in the dry state of the porous film. It is more preferable. The porosity Po (%) of the porous film is determined from the thickness of the porous film including the height of the concave or convex pattern described above, the mass per area, and the density of the constituent components as follows. formula:
Po = {1- (m / t) / (Σa _i · ρ _i )} × 100
{Wherein, a _i is the ratio of component i when the total mass is 1, ρ _i is the density (g / cm ³ ) of component i, and m is the unit area of the porous film Per unit mass (g / cm ² ), and t is the thickness (cm) of the porous film. }
Can be calculated by calculating the sum for each component i.

  The thickness of the porous film in the present embodiment is preferably 2 μm or more and 200 μm or less, including the height of the concave or convex pattern described above, in any of the single layer structure and the multilayer structure, and is 3 μm or more and 100 μm or less. Is more preferably 4 μm or more and 30 μm or less, and particularly preferably 25 μm or less. When the thickness of the porous film is 2 μm or more, the mechanical strength of the porous film tends to be further improved. Moreover, since the occupied volume of the porous film in a battery reduces because the thickness of a porous film is 200 micrometers or less, it exists in the tendency for a non-aqueous electrolyte battery to become higher capacity | capacitance and to improve ion permeability.

  The air permeability of the porous film in the present embodiment is preferably 10 seconds / 100 cc or more and 500 seconds / 100 cc or less, more preferably 20 seconds / 100 cc or more and 450 seconds / 100 cc or less, and further preferably 30 seconds. / 100cc or more and 450 seconds / 100cc or less. When the air permeability is 10 seconds / 100 cc or more, self-discharge tends to be less when the porous film is used in a nonaqueous electrolyte battery. Further, when the air permeability is 500 seconds / 100 cc or less, better charge / discharge characteristics tend to be obtained.

  Further, when the porous film has a porous layer containing inorganic particles and / or organic particles and a nonwoven fabric or microporous film as a base material, the porous film containing inorganic particles and / or organic particles The thickness is preferably 1 μm to 10 μm.

  Furthermore, when the porous film has a porous layer containing inorganic particles and / or organic particles and a nonwoven fabric or microporous film as a base material, or in addition to these layers, another layer (others) In the case of having a porous layer containing inorganic particles or resin fine particles as a main component, the thickness of the nonwoven fabric or porous film serving as a substrate is preferably 5 μm to 40 μm.

  Moreover, when a porous film has another layer, it is preferable that the thickness of this porous layer is 1 micrometer-10 micrometers.

  The porous layer containing inorganic particles and / or organic particles is prepared by dispersing or dissolving inorganic particles and / or organic particles, a binder, etc. in water or an organic solvent (for example, paste, slurry, etc.) It is applied to a place where such a porous layer is expected to be formed and dried, or the composition is applied to a substrate such as a resin film, dried and then peeled off to form an independent film. can do.

  In addition, a composition prepared by dispersing or dissolving the above-described particles, binder, or the like in water or an organic solvent (for example, paste, slurry, etc.) for another layer is also planned for the formation of such a porous layer. It can be formed through a step of applying to and dried, or the composition can be applied to a substrate such as a resin film, dried and then peeled to form an independent film.

  The porous layer containing inorganic particles and / or resin fine particles as a main component preferably further contains a water-soluble polymer. As the water-soluble polymer, a known polymer generally known as an aqueous dispersant or an aqueous thickener can be used.

  Examples of the aqueous dispersant include, for example, organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), methacrylic acid-based or acrylic acid-based (co) polymer polyflow No. 75, no. 90, no. 95 (both manufactured by Kyoeisha Chemical Co., Ltd.), W001 (Yusho Co., Ltd.) and other cationic surfactants; polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl Nonionic surfactants such as phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, and sorbitan fatty acid ester; anions such as W004, W005, and W017 (all of which are Yusho Co., Ltd.) EFKA-46, EFKA-47, EFKA-47EA, EFKA polymer 100, EFKA polymer 400, EFKA polymer 401, EFKA polymer 450 (all of which are Ciba Specialty Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100, SN Dispersant 5040, 5033, 5034, 5468, 5020 (all from Sampnoco) and Solsperse 3000 Polymer dispersing agents such as various Solsperse dispersing agents (all manufactured by Lubrizol) such as 5000, 9000, 12000, 13240, 13940, 17000, 24000, 26000, 28000, and 41000; Adeka Pluronic L31, F38, L42, L44 L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, and P-123 (all manufactured by ADEKA Corporation), Ionette S-20 (three Manufactured by Kasei Kogyo Co., Ltd.), DISPERBYK 101, 103, 106, 108, 109, 110, 111, 112, 116, 118, 130, 140, 142, 162, 163, 164, 166, 167, 170, 171, 174, 176, 180, 182, 184, 190, 191, 194N, 2000, 2001, 2010, 2015, 2050, 2055, 2150, 2152, 2155, and 2164 (all manufactured by Big Chemie); Demole EP , Poise 520, poise 521, poise 530, poise 535, and demole P (all manufactured by Kao Corporation); Aron T-50, -6012, A-6017, AT-40H, A-6001, A- 30SL, A-6114, A-210, SD-10, A-671 , A-6330, CMA-101, Jurimer (registered trademark) AC-10NPD (all manufactured by Toagosei Co., Ltd.), and Nuosperse FX-605, FX-609, FX-600, and FX-504 (all And various polycarboxylic acid dispersants such as those manufactured by Elementis). In addition to the above, examples of the dispersant include oligomers or polymers having a polar group at the molecular end or side chain, such as an acrylic copolymer. A dispersing agent may be used individually by 1 type, or may be used together 2 or more types.

Examples of aqueous thickeners include, for example, SEPIGEL 305, NS, EG, FL, SEPPLUS 265, S, 400, SEPINOV EMT10, P88, and SEPMAX ZEN (all manufactured by Seiwa Kasei Co., Ltd.); Aron A-10H, A- 20P-X, A-20L, A-30, A-7075, A-7100, A-7185, A-7195, A-7255, B-300K, B-500K, Jurimer (registered trademark) AC-10LHPK, AC -10SHP, Rheological 260H, 845H, and Junron PW-120 (all manufactured by Toagosei Co., Ltd.); DISPERBYK 410, 411, 415, 420, 425, 428, 430, 431, 7410ET, 7411ES, 7420ES, and OPTIFLO-L1400 ( Both are Big Chemie ), Koscut GA468 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), fibrin derivative materials (carboxymethylcellulose, methylcellulose, hydroxycellulose, etc.), protein materials (casein, sodium caseinate, ammonium caseinate, etc.), alginate materials (Sodium alginate, etc.), polyvinyl materials (polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl benzyl ether copolymer, etc.), polyacrylic acid materials (polyacrylic acid soda, polyacrylic acid-polymethacrylic acid copolymer, etc.), Polyether materials (pluronic polyethers, polyether dialkyl esters, polyether dialkyl ethers, polyether urethane modified products, polyether epoxy modified products, etc.) and maleic anhydride copolymer materials (Partial ester of vinyl ether-maleic anhydride copolymer, drying oil fatty acid allyl alcohol ester-half ester of maleic anhydride, etc.). In addition to the above, examples of the thickener include polyamide wax salt, acetylene glycol, zentane gum, oligomer or polymer having a polar group at the molecular end or side chain.
A thickener may be used individually by 1 type, or may be used together 2 or more types.

  The content of the water-soluble polymer in the porous layer containing the formed inorganic particles and / or organic particles is 0.1% by mass to 100% by mass with respect to the total solid content of the inorganic particles and / or organic particles. The range is preferably 0.2% by mass to 10% by mass.

You may provide the layer which has a composition different from a base material on both surfaces of the base material which gave the pattern of concave or convex shape. In addition, when a layer having a composition different from that of the base material is provided on one side of the main surface of the base material provided with a concave or convex pattern, it may be formed on the main surface provided with the pattern. You may form in the main surface opposite to the main surface which gave. When the substrate has a pattern, it is preferable to provide the pattern on the main surface opposite to the layer having a composition different from that of the substrate in order to effectively exhibit the effect of the pattern.
It is also an embodiment of the present invention that a pattern is applied to a layer having a composition different from that of the substrate without applying a pattern to the substrate. Also, a layer having a composition different from that of the substrate having a composition different from that of the upper layer, or a layer having a composition different from that of the substrate, between the layer having a composition different from that of the patterned substrate and the substrate. Providing is also an embodiment of the present invention. Furthermore, a layer having a composition different from that of the substrate may be formed on both surfaces of the substrate, and one or both of them may be patterned.

  Another aspect of the present invention is a nonaqueous electrolyte battery containing a positive electrode, a laminate in which the porous film described above and the negative electrode are laminated, or a rolled body thereof, and a nonaqueous electrolyte. A typical example of the nonaqueous electrolyte battery is a lithium ion secondary battery. From the viewpoint of the movement of lithium ions in the battery and the life characteristics of the battery, the patterned surface of the porous film preferably faces the negative electrode side.

[Positive electrode]
The positive electrode preferably includes a positive electrode active material, a conductive material, a binder, and a current collector.

｛式中、Ｍは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示し、０＜ｘ≦１．３、０．２＜ｙ＜０．８、かつ３．５＜ｚ＜４．５である。｝
で表される酸化物；
下記一般式（２）：

｛式中、Ｍは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示し、０＜ｘ≦１．３、０．８＜ｙ＜１．２、かつ１．８＜ｚ＜２．２である。｝
で表される層状酸化物；
下記一般式（３）：

｛式中、Ｍａは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示し、かつ０．２≦ｘ≦０．７である。｝
で表されるスピネル型酸化物；
下記一般式（４）：

｛式中、Ｍｃは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示す。｝で表される酸化物と下記一般式（５）：

｛式中、Ｍｄは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示す。｝で表される酸化物との複合酸化物であって、下記一般式（６）：

｛式中、Ｍｃ及びＭｄは、それぞれ上記式（４）及び（５）におけるＭｃ及びＭｄと同義であり、かつ０．１≦ｚ≦０．９である。｝
で表される、Ｌｉが過剰な層状の酸化物正極活物質；
下記一般式（７）：

｛式中、Ｍｂは、Ｍｎ及びＣｏから成る群より選ばれる少なくとも１種の元素を示し、かつ０≦ｙ≦１．０である。｝
で表されるオリビン型正極活物質；及び
下記一般式（８）：

｛式中、Ｍｅは、遷移金属元素から成る群より選ばれる少なくとも１種の元素を示す。｝で表される化合物が挙げられる。これらの正極活物質は、１種を単独で用いても２種以上を併用してもよい。 As the positive electrode active material that can be included in the positive electrode, a known material that can electrochemically occlude and release lithium ions can be used. Among these, as the positive electrode active material, a material containing lithium is preferable. As the positive electrode active material, for example,
The following general formula (1):

{Wherein M represents at least one element selected from the group consisting of transition metal elements, 0 <x ≦ 1.3, 0.2 <y <0.8, and 3.5 <z <4. .5. }
An oxide represented by:
The following general formula (2):

{Wherein M represents at least one element selected from the group consisting of transition metal elements, 0 <x ≦ 1.3, 0.8 <y <1.2, and 1.8 <z <2. .2. }
A layered oxide represented by:
The following general formula (3):

{In the formula, Ma represents at least one element selected from the group consisting of transition metal elements, and 0.2 ≦ x ≦ 0.7. }
A spinel oxide represented by:
The following general formula (4):

{In the formula, Mc represents at least one element selected from the group consisting of transition metal elements. } And the following general formula (5):

{Wherein Md represents at least one element selected from the group consisting of transition metal elements. } Is a composite oxide with an oxide represented by the following general formula (6):

{In the formula, Mc and Md are synonymous with Mc and Md in the above formulas (4) and (5), respectively, and 0.1 ≦ z ≦ 0.9. }
Li-excess layered oxide positive electrode active material represented by:
The following general formula (7):

{In the formula, Mb represents at least one element selected from the group consisting of Mn and Co, and 0 ≦ y ≦ 1.0. }
An olivine-type positive electrode active material represented by: and the following general formula (8):

{In the formula, Me represents at least one element selected from the group consisting of transition metal elements. } The compound represented by this is mentioned. These positive electrode active materials may be used alone or in combination of two or more.

  In addition, in order to form the positive electrode used in this embodiment, a conductive material, a binder, and a current collector known in this technical field may be used.

  Further, in the positive electrode mixture layer according to the positive electrode, the content of the positive electrode active material is adjusted to 87% by mass to 99% by mass, the content of the conductive auxiliary agent is adjusted to 0.5% by mass to 10% by mass, and It is preferable to adjust the content of the binder to 0.5% by mass to 10% by mass.

[Negative electrode]
The negative electrode used in the present embodiment preferably includes a negative electrode active material, a binder, and a current collector.

  As the negative electrode active material that can be included in the negative electrode, a known material that can electrochemically occlude and release lithium ions can be used. Such a negative electrode active material is not particularly limited, and for example, carbon materials such as graphite powder, mesophase carbon fiber, and mesophase microspheres; and metals, alloys, oxides, and nitrides are preferable. These may be used alone or in combination of two or more.

  As the binder that can be included in the negative electrode, a known material that can bind at least two of the negative electrode active material, the conductive material that can be included in the negative electrode, and the current collector that can be included in the negative electrode can be used. Such a binder is not particularly limited, and for example, carboxymethyl cellulose, styrene-butadiene crosslinked rubber latex, acrylic latex, and polyvinylidene fluoride are preferable. These may be used alone or in combination of two or more.

  Although it does not specifically limit as a collector which can be contained in a negative electrode, For example, metal foil, such as copper, nickel, and stainless steel; Expand metal; Punch metal; Foam metal; Carbon cloth; These may be used alone or in combination of two or more.

  Moreover, in the negative mix layer concerning a negative electrode, content of a negative electrode active material is adjusted to 88 mass%-99 mass%, and / or content of a binder is adjusted to 0.5 mass%-12 mass%. Preferably, when a conductive auxiliary is used, the content of the conductive auxiliary is preferably adjusted to 0.5% by mass to 12% by mass.

[Nonaqueous electrolyte]
As the non-aqueous electrolyte used in the present embodiment, for example, a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent is used. The lithium salt is not particularly limited, and a conventionally known lithium salt can be used. Such a lithium salt is not particularly limited. For example, LiPF ₆ (lithium hexafluorophosphate), LiClO ₄ , LiBF ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{2k + 1} [wherein k is an integer of 1 to 8], LiN (SO ₂ C _k F _{2k + 1} ) ₂ [wherein k is an integer of 1 to 8], LiPF _n (C _k F _{2k + 1} ) _6-n [wherein , N is an integer of 1 to 5 and k is an integer of 1 to 8], LiPF ₄ (C ₂ O ₄ ), and LiPF ₂ (C ₂ O ₄ ) ₂ . Among these, LiPF ₆ is preferable. By using LiPF ₆ , the battery characteristics and safety tend to be superior even at high temperatures. These lithium salts may be used individually by 1 type, or may use 2 or more types together.

  The nonaqueous solvent used for the nonaqueous electrolyte in the present embodiment is not particularly limited, and a conventionally known one can be used. Examples of such non-aqueous solvents include aprotic polar solvents.

  The aprotic polar solvent is not particularly limited. For example, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate. Cyclic carbonates such as trifluoromethylethylene carbonate, fluoroethylene carbonate and 4,5-difluoroethylene carbonate; lactones such as γ-ptyrolactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; Dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate Chain carbonates such as boronate, dibutyl carbonate, ethylpropyl carbonate and methyl trifluoroethyl carbonate; nitriles such as acetonitrile; chain ethers such as dimethyl ether; chain carboxylic acid esters such as methyl propionate; and chains such as dimethoxyethane An ether carbonate compound is mentioned. One of these may be used alone, or two or more may be used in combination.

  The non-aqueous electrolyte may contain other additives as necessary. Examples of such additives include, but are not limited to, lithium salts other than those exemplified above, unsaturated bond-containing carbonates, halogen atom-containing carbonates, carboxylic acid anhydrides, sulfur atom-containing compounds (for example, sulfides, disulfides). Sulfonic acid ester, sulfite, sulfate, sulfonic acid anhydride, etc.), nitrile group-containing compounds and the like.

Specific examples of other additives are as follows:
Lithium salts: for example, lithium monofluorophosphate, lithium difluorophosphate, lithium bis (oxalato) borate, lithium difluoro (oxalato) borate, lithium tetrafluoro (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, etc .;
Unsaturated bond-containing carbonate: for example, vinylene carbonate, vinyl ethylene carbonate, etc .;
Halogen atom-containing carbonate: for example, fluoroethylene carbonate, trifluoromethylethylene carbonate, etc .;
Carboxylic anhydride: for example, acetic anhydride, benzoic anhydride, succinic anhydride, maleic anhydride, etc .;
Sulfur atom-containing compounds: for example, ethylene sulfite, 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, ethylene sulfate, vinylene sulfate, etc.
Nitrile group-containing compound: for example, succinonitrile.

When the nonaqueous electrolyte contains the other additives described above, the cycle characteristics of the battery tend to be further improved.
Among them, at least one selected from the group consisting of lithium difluorophosphate and lithium monofluorophosphate is preferable from the viewpoint of further improving the cycle characteristics of the battery. The content of at least one additive selected from the group consisting of lithium difluorophosphate and lithium monofluorophosphate is preferably 0.001% by mass or more with respect to 100% by mass of the nonaqueous electrolyte, and 0.005 More preferably, it is more preferably 0.02% by mass or more. When the content is 0.001% by mass or more, the cycle life of the lithium ion secondary battery tends to be further improved. Further, the content is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less. When the content is 3% by mass or less, the ion conductivity of the lithium ion secondary battery tends to be further improved.
The content of other additives in the nonaqueous electrolyte can be confirmed by NMR measurement such as ³¹ P-NMR and ¹⁹ F-NMR.

  The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.5 mol / L to 6.0 mol / L. From the viewpoint of reducing the viscosity of the non-aqueous electrolyte, the concentration of the lithium salt in the non-aqueous electrolyte is more preferably 0.9 mol / L to 1.25 mol / L. The concentration of the lithium salt in the non-aqueous electrolyte can be selected according to the purpose.

  In the present embodiment, the nonaqueous electrolyte may be a liquid electrolyte or a solid electrolyte.

[Configuration, form and use of non-aqueous electrolyte battery]
In the nonaqueous electrolyte battery according to the present embodiment, the positive electrode and the negative electrode are used in the form of a laminated body laminated via a porous film, or in the form of an electrode wound body obtained by further winding the laminated body. Can do.

  Examples of the form of the nonaqueous electrolyte battery according to the present embodiment include a cylindrical shape (for example, a rectangular tube shape, a cylindrical shape, etc.) using a steel can, an aluminum can, or the like as an outer can. Moreover, the nonaqueous electrolyte battery which concerns on this embodiment can also be formed using the laminated film which vapor-deposited the metal as an exterior body.

  When the nonaqueous electrolyte battery according to the present embodiment is a lithium ion secondary battery, the positive electrode, the porous film, the uneven region, and the negative electrode are laminated in this order, or a rolled body thereof, The water electrolyte is preferably contained in the lithium ion secondary battery. By arranging a plurality of components of the lithium ion secondary battery in such an order, the movement of lithium ions within the battery is ensured, and the adsorption of substances that affect the life characteristics or safety of the battery is remarkable. Become.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. Unless otherwise specified, various measurements and evaluations were performed under conditions of a room temperature of 23 ° C., 1 atm, and a relative humidity of 50%.

<Evaluation of life characteristics of nonaqueous electrolyte secondary battery>
(Initial charge / discharge)
The obtained non-aqueous electrolyte secondary battery (hereinafter, also simply referred to as “battery”) is housed in a thermostatic chamber (manufactured by Futaba Kagaku Co., Ltd., thermostatic chamber PLM-73S) set at 60 ° C. The battery was connected to a charge / discharge device ACD-01 manufactured by Electronics Corporation. Next, the battery was charged at a constant current of 0.05 C, reached 4.35 V, charged for 2 hours at a constant voltage of 4.35 V, and discharged to 3.0 V at a constant current of 0.2 C. 1C is a current value at which the battery is discharged in one hour.

(Cycle test)
The battery after the initial charging / discharging is accommodated in a thermostatic chamber (manufactured by Futaba Kagaku Co., Ltd., thermostatic chamber PLM-73S) set to 60 ° C., and a charging / discharging device (manufactured by Asuka Electronics Co., Ltd., charging / discharging device ACD-01) Connected to. Next, the battery was charged to 4.35V with a constant current of 2C, reached 4.35V, charged for 30 minutes with a constant voltage of 4.35V, and discharged to 3.0V with a constant current of 2C. This series of charge and discharge was defined as one cycle, and 99 cycles of charge and discharge were performed. At this time, the discharge capacity retention rate was evaluated. A similar test was conducted at 0 ° C.

The discharge capacity retention rate (unit:%) is calculated from the following equation: from the discharge capacity at the first cycle and the discharge capacity at the 100th cycle:
Discharge capacity retention rate = (discharge capacity at the 100th cycle / discharge capacity at the first cycle) × 100
Calculated according to

<Evaluation of battery swelling>
As for battery swelling, when the volume of the battery after the cycle test is increased by 10% or more with respect to the volume before the initial charge / discharge, the battery swelling is “Yes”. Swelling: “No”.

[Example 1]
<Preparation of separator>
47.5 parts by mass of a polyethylene homopolymer having an Mv (viscosity average molecular weight) of 700,000, 47.5 parts by mass of a polyethylene homopolymer having an Mv of 250,000, and 5 parts by mass of a polypropylene homopolymer having an Mv of 400,000 Were dry blended using a tumbler blender to obtain a polyolefin resin mixture. 1% by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant is added to 99% by mass of the obtained polyolefin resin mixture. Then, a polyolefin resin composition was obtained by dry blending again using a tumbler blender.

The obtained polyolefin resin composition was substituted with nitrogen, and then supplied to the twin-screw extruder by a feeder under a nitrogen atmosphere. Further, liquid paraffin (kinematic viscosity at 37.78 ° C .: 7.59 × 10 ⁻⁵ m ² / s) was injected into the extruder cylinder by a plunger pump. The feeder and the pump were adjusted so that the liquid paraffin content ratio in the total mixture to be extruded was 66 mass% (resin composition concentration was 34%). The melt kneading conditions were a set temperature of 200 ° C., a screw rotation speed of 100 rpm, and a discharge rate of 12 kg / h.

  Subsequently, the melt-kneaded product was extruded and cast onto a cooling roll controlled at a surface temperature of 25 ° C. through a T-die, thereby obtaining a gel sheet having a thickness of 2,200 μm. Next, the obtained gel sheet was guided to a simultaneous biaxial tenter stretching machine, and biaxial stretching was performed. The set stretching conditions were an MD magnification of 7.3 times, a TD magnification of 6.3 times, and a preset temperature of 125 ° C. Next, the biaxially stretched gel sheet was introduced into a methyl ethyl ketone bath and sufficiently immersed in methyl ethyl ketone to extract and remove the liquid paraffin, and then the methyl ethyl ketone was removed by drying. Finally, the dried gel sheet was guided to a TD tenter, and stretched and thermally relaxed to obtain a polyolefin microporous membrane. The stretching temperature was 122 ° C., the thermal relaxation temperature was 133 ° C., the TD maximum magnification was 1.65 times, and the relaxation rate was 0.9. The resulting polyolefin microporous film had a thickness of 16 μm and a porosity of 50%.

<Preparation of fine pattern>
(A) Production of cylindrical master mold An uneven structure was formed on the surface of cylindrical quartz glass by a direct drawing lithography method using a semiconductor laser. First, the quartz glass surface was thoroughly cleaned to remove particles. Subsequently, a resist layer was formed on the surface of the cylindrical quartz glass by a sputtering method. In the sputtering method, a 20 nm resist layer was formed using CuO as a target (resist layer). Subsequently, the surface of the resist layer was exposed using a semiconductor laser while rotating the cylindrical quartz glass. At this time, the arrangement of nanostructures was controlled by the exposure pattern. Next, the resist layer after exposure was developed. The development of the resist layer was processed using a 0.03% by mass glycine aqueous solution. Next, using the developed resist layer as a mask, the etching layer (quartz glass) was etched by dry etching. Dry etching was performed using SF ₆ as an etching gas. The size of the opening of the concavo-convex structure and the depth of the concavo-convex structure were adjusted by changing the treatment time. Finally, only the resist layer residue was peeled off from the cylindrical quartz glass having a concavo-convex structure on its surface using hydrochloric acid having a pH of 1.

  Fluorine-based surface treatment agent (Durasurf (registered trademark) HD-1101Z, manufactured by Daikin Chemical Industries, Ltd.) is applied to the concavo-convex structure of the obtained cylindrical quartz glass, heated at 60 ° C. for 1 hour, and then at room temperature. It was left to stand for immobilization. Thereafter, the concavo-convex structure of the cylindrical quartz glass was washed three times with a cleaning agent (Durasurf HD-ZV, manufactured by Daikin Chemical Industries, Ltd.) to obtain a cylindrical master mold.

(B) Production of porous film having concavo-convex structure The produced cylindrical master mold was used as a mold, and a thermal imprint method was applied to the polyolefin microporous film to produce a porous film having a fine pattern continuously. . The temperature of the cylindrical master mold was set to 80 ° C. Table 1 shows the pattern shape of the fine pattern on the microporous polyolefin film produced by the pattern of the master mold and thermal imprinting.

<Preparation of positive electrode>
93.9: 3.3: Solid content ratio of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as a positive electrode active material, acetylene black powder as a conductive additive, and a polyvinylidene fluoride solution as a binder. Mixed at a mass ratio of 2.8. To the obtained mixture, N-methyl-2-pyrrolidone as a dispersion solvent was added so as to have a solid content of 35% by mass and further mixed to prepare a slurry solution. This slurry solution was applied to both surfaces of an aluminum foil having a thickness of 10 μm. At this time, a part of the aluminum foil was exposed. Then, the solvent was removed by drying and rolled with a roll press. The rolled sample is cut so that the size of the coated part is 30 mm × 50 mm and includes the exposed part of the aluminum foil, and an aluminum lead piece for taking out the current is welded to the exposed part of the aluminum foil. Thus, a positive electrode was obtained.

<Production of negative electrode>
Graphite powder as a negative electrode active material and styrene butadiene rubber and carboxymethyl cellulose aqueous solution as a binder were mixed at a solid content mass ratio of 97.5: 1.5: 1.0. The obtained mixture was added to water as a dispersion solvent so that the solid content concentration was 45% by mass to prepare a slurry-like solution. This slurry solution was applied to one and both sides of a 10 μm thick copper foil. At this time, a part of the copper foil was exposed. Then, the solvent was removed by drying and rolled with a roll press. The sample after rolling is cut so that the size of the coated part is 32 mm × 52 mm and includes the exposed part of the copper foil, and a nickel lead piece for taking out the current is welded to the exposed part of the copper foil. Thus, a negative electrode was obtained.

<Preparation of nonaqueous electrolyte>
In an argon gas atmosphere, LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 1: 2 so as to be 1 mol / L, and a non-aqueous electrolyte ( A non-aqueous electrolyte solution was obtained.

<Production of nonaqueous electrolyte battery>
The positive electrode and the negative electrode were overlapped with the separator interposed therebetween to form a laminated electrode body. In addition, the porous film which has a fine pattern was arrange | positioned so that the fine pattern side might oppose a negative electrode. This laminated electrode body was inserted into an aluminum laminate outer package of 80 × 60 mm. Next, the nonaqueous electrolyte (nonaqueous electrolyte) is injected into the exterior body, and then the opening of the exterior body is sealed, and the nonaqueous electrolyte battery (lithium ion secondary battery) having the laminated electrode body inside (Hereinafter also simply referred to as “battery”). The rated capacity of the obtained nonaqueous electrolyte battery was 90 mAh. As a result of the evaluation of the life characteristics described above, the discharge capacity retention rate in the 60 ° C. cycle test of the battery was 92%, and the battery did not swell. Moreover, the discharge capacity maintenance factor by the 0 degreeC cycle test of the battery was 32%, and the swelling of the battery was "none".

[Examples 2 to 6]
A polyolefin microporous membrane was obtained in the same manner as in Example 1, and a fine pattern different from that in Example 1 was produced by thermal imprinting. The battery was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 7]
(A) Production of resin layer having concavo-convex structure The produced cylindrical master mold was used as a mold, and an optical nanoimprint method was applied to continuously produce a mold G1. Subsequently, a mold G2 was continuously obtained by an optical nanoimprint method using the mold G1 as a template. The mold G2 was used as a resin layer having a concavo-convex structure and a supporting substrate.
The material 1 shown below was applied to the easy-adhesion surface of PET film A-4100 (manufactured by Toyobo Co., Ltd .: width 300 mm, thickness 100 μm) by microgravure coating (manufactured by Yurai Seiki Co., Ltd.) to a coating film thickness of 2 μm. . Next, the PET film coated with the material 1 is pressed against the cylindrical master mold with a nip roll so that the integrated exposure amount under the center of the lamp is 1500 mJ / cm ^{2 at} 25 ° C. and 60% humidity in the air. In addition, a UV-irradiated UV exposure apparatus (H bulb) manufactured by Fusion UV Systems Japan Co., Ltd. is used to irradiate ultraviolet rays to carry out photocuring continuously. 200 m, width 300 mm).

  Next, the mold G1 was regarded as a template, and the optical nanoimprint method was applied to continuously produce the mold G2.

Material 1 was applied to an easy-adhesion surface of PET film A-4100 (manufactured by Toyobo Co., Ltd .: width 300 mm, thickness 100 μm) by microgravure coating (manufactured by Yurai Seiki Co., Ltd.) so as to have a coating film thickness of 2 μm. Next, the PET film coated with the material 1 is pressed against the concavo-convex structure surface of the mold G1 with a nip roll (0.1 MPa), and the integrated exposure amount under the center of the lamp is 25 ° C. and 60% humidity in the atmosphere. Reel with a concavo-convex structure transferred to the surface by irradiating with UV light using a UV exposure device (H bulb) manufactured by Fusion UV Systems Japan Co., Ltd. so that it becomes 1200 mJ / cm ^2. A plurality of resin molds G2 (length 200 m, width 300 mm) were obtained.
Material 1 ... Fluorine-containing urethane (meth) acrylate (OPTOOL (registered trademark) DAC HP (manufactured by Daikin Industries)): Trimethylolpropane (EO-modified) triacrylate (M350 (manufactured by Toagosei Co., Ltd.)): 1-hydroxy Cyclohexyl phenyl ketone (Irgacure (registered trademark) 184 (manufactured by BASF)): 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (Irgacure 369 (manufactured by BASF)) = 17 .5 g: 100 g: 5.5 g: material mixed at 2.0 g

(B) Production of a porous film having a two-layer structure having a concavo-convex structure In 100 parts by mass of ion-exchanged water, 29 parts by mass of alumina and an aqueous solution of ammonium polycarboxylate (SN Dispersant 5468 manufactured by San Nopco) 0.29 parts by mass After mixing the parts, a bead mill treatment was performed to adjust the average particle size (D50) to 450 nm to obtain a dispersion. Furthermore, with respect to 100 parts by mass of the obtained dispersion, 2.2 parts by mass of an acrylic latex suspension (solid content concentration 40%, average particle diameter 150 nm) as a binder and a fluorosurfactant (AGC Seimi Chemical Co., Ltd.) (Surflon S211) 0.1 parts by mass was mixed to prepare a uniform porous layer forming composition. The average particle size of alumina in the above dispersion is a particle size distribution in which the particle size distribution is measured using a laser particle size distribution measuring device (Microtrack MT3300EX manufactured by Nikkiso Co., Ltd.) and the volume cumulative frequency is 50%. Was the average particle size (μm). Moreover, the average particle diameter of the resin latex binder was determined as the average particle diameter by measuring the volume average particle diameter (nm) using a particle size measuring apparatus (LEC & TRATCHUPA 150 manufactured by LEED & NORTHRUP) using a light scattering method.

  Next, the porous layer forming composition is applied to the surface of the mold G2 using a micro gravure coater, dried at 60 ° C. to remove ion-exchanged water, and a porous layer having a thickness of 4 μm on the mold G2. Arranged. Next, the porous layer on the mold G2 is thermally transferred onto the polyolefin microporous film after stretching and thermal relaxation performed in Example 1, the mold is removed, and an alumina-containing porous layer having an uneven structure is provided. A two-layer porous film was obtained.

[Examples 8 to 12]
A porous film having a multilayer structure was obtained in the same manner as in Example 7, and a pattern was produced using a fine pattern different from that in Example 7. The battery was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
Battery evaluation was performed in the same manner as in Example 1 using the separator after stretching and thermal relaxation. The results are shown in Table 1.

[Comparative Example 2]
Embossing was used instead of the cylindrical master mold. The embossed pattern of the embossing roll was an oblique lattice, the mesh was 100 pieces / inch, the depth was 0.010 mm, and the surface temperature was controlled at 80 ° C.

[Comparative Example 3]
Example 10 Using a screen printer in which a grid-like pattern composed of 450 μm × 450 μm eyes (size of a coating film surrounded by grooves) and a 50 μm gap (groove width of groove openings) is formed, A porous film was formed from the same porous layer forming composition.

  The measurement and evaluation results of Examples 1 to 12 and Comparative Examples 1 to 3 are shown in Table 1 below.

  The porous film according to the present embodiment is used for a separator for a non-aqueous electrolyte secondary battery, etc., and the non-aqueous electrolyte secondary battery according to the present embodiment is used for a power source for various consumer devices, a power source for automobiles, etc. Can be done.

DESCRIPTION OF SYMBOLS 10 Porous film base material 11 Pattern area | region 11a Convex part 11b Concave part

Claims (19)

  A porous film having a concave or convex pattern on at least one surface, and the length (L) of the major axis of the concave or convex pattern being 0.5 μm or more and 100 μm or less.   The porous film according to claim 1, wherein the concave or convex pattern is different from a pattern of pores inside the porous film.   The porous film according to claim 1 or 2, wherein a pattern pitch (P) of the concave or convex pattern is 1 µm or more and 110 µm or less.   The porous film according to claim 1, wherein a height of the concave or convex pattern is 25 μm or less.   The porous film according to any one of claims 1 to 4, wherein a total film thickness of the porous film including a height of the concave or convex pattern is 25 µm or less.   L / P, which is the ratio of the major axis length (L) of the concave or convex pattern to the pattern pitch (P) of the pattern, is 0.01 or more and 0.9 or less. The porous film according to any one of the above. The concave or convex pattern has at least one surface, the length (L) of the major axis of the concave or convex pattern exceeds 100 μm, and the width of the concave or convex pattern (L _W ) is 0 A porous film having a thickness of 5 μm or more and 100 μm or less.   The porous film according to claim 7, wherein the concave or convex pattern is different from a pattern of pores inside the porous film.   The porous film according to claim 7 or 8, wherein a pattern pitch (P) of the concave or convex pattern exceeds 110 µm.   The porous film according to any one of claims 7 to 9, wherein a height of the concave or convex pattern is 25 µm or less.   The porous film according to any one of claims 7 to 10, wherein a total film thickness of the porous film including a height of the concave or convex pattern is 25 µm or less.   L / P, which is a ratio of the length (L) of the major axis of the concave or convex pattern to the pattern pitch (P) of the pattern, is 0.01 or more and 0.9 or less. The porous film according to any one of the above. L _W / P _W which is the ratio of the width (L _W ) of the concave or convex pattern to the pattern pitch (P _W ) in the direction perpendicular to the concave or convex pattern pitch (L) is 0.01 The porous film according to any one of claims 7 to 12, which is 1.0 or more and 13 or less.   The porous film is composed of a porous layer containing polyolefin as a main component and a porous layer containing inorganic particles and / or organic particles as a main component, and at least one surface of the porous layer containing the polyolefin as a main component. The porous film of any one of Claims 1-13 which has the said concave or convex pattern.   The porous film comprises a porous layer containing polyolefin as a main component and a porous layer containing inorganic particles and / or organic particles as a main component, and includes the inorganic particles and / or organic particles as a main component. The porous film according to any one of claims 1 to 13, wherein the concave or convex pattern is on at least one surface of the porous layer.   The porous material according to any one of claims 1 to 13, wherein a length of a major axis of the concave or convex pattern is a diameter of a circle having a minimum area including the concave or convex pattern inside. the film.   The porous film according to claim 16, wherein the circle is in contact with the concave or convex pattern at at least two points.   The lithium ion secondary battery containing the positive electrode, the laminated body by which the porous film and negative electrode of any one of Claims 1-17 are laminated | stacked, or the winding body of this laminated body, and a nonaqueous electrolyte.   The lithium ion secondary battery according to claim 18, wherein a surface of the porous film having the concave or convex pattern faces the negative electrode side.

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