JPWO2012046600A1 - Conductive crosslinked film, method for producing the film, and use of the film - Google Patents

Abstract

The present invention provides a conductive cross-linked film (current collector) having excellent peel strength between a mixture layer and a current collector when producing an electrode for a nonaqueous electrolyte secondary battery, and the conductive cross-linking. A non-aqueous electrolyte secondary battery electrode formed using a film, a non-aqueous electrolyte secondary battery, and a method for producing a conductive crosslinked film capable of efficiently producing the conductive crosslinked film The purpose is to provide. The conductive crosslinked film of the present invention comprises a vinylidene fluoride polymer (a) 40 to 93 parts by weight, a conductive carbon black (b) 5 to 25 parts by weight, a crosslinking agent (c) 2 to 30 parts by weight, and a lubricant. (D) It is formed by crosslinking a vinylidene fluoride resin composition containing 0 to 5 parts by weight, and can be used as a current collector.

Description

  The present invention relates to a conductive crosslinked film, a method for producing the film, and uses of the film.

  In recent years, the development of electronic technology has been remarkable, and various devices have been reduced in size and weight. Along with the reduction in size and weight of the electronic device, there is a demand for reduction in size and weight of the battery serving as the power source. Non-aqueous electrolyte secondary batteries using lithium are mainly used as power sources for small electronic devices used in homes such as mobile phones, personal computers, and video camcorders as batteries that can obtain large energy with a small volume and weight. ing. In addition, it has been proposed to use a non-aqueous electrolyte secondary battery as a power source for a hybrid car, an electric vehicle, etc. In this case, vibration is applied to the non-aqueous electrolyte secondary battery during its use. In some cases, peeling between members, sliding off of the active material, or the like becomes a problem.

  The electrode of the nonaqueous electrolyte secondary battery is usually formed from a current collector and a mixture for a nonaqueous electrolyte secondary battery, and the mixture obtained from the mixture for a nonaqueous electrolyte secondary battery on the current collector A layer is formed. Note that a mixture for a nonaqueous electrolyte secondary battery usually includes a binder resin, an electrode active material, and an organic solvent that act as a binder with the current collector.

  Conventionally, it has been proposed to use a metal foil as a current collector and polyvinylidene fluoride (PVDF) as a binder (binder resin). PVDF has excellent electrochemical stability and mechanical properties, and a nonaqueous electrolyte secondary battery mixture containing PVDF is stable. However, since PVDF has weak adhesiveness with a metal foil as a current collector, peeling of the mixture layer from the current collector has been a problem.

  In order to improve the adhesiveness between the mixture layer and the current collector, a method using PVDF having a functional group such as a carboxyl group introduced as a binder has been proposed (for example, see Patent Documents 1 to 5). .

  However, even when PVDF into which a functional group such as a carboxyl group has been introduced is used as a binder, the adhesive strength with a metal foil as a current collector is not limited to that of a non-aqueous electrolyte secondary battery as a hybrid car, When used as a power source for automobiles and the like, it has not been sufficient yet.

  By the way, as a current collector, a resin current collector formed of a conductive resin composition containing a resin and a conductive filler instead of a metal foil has been proposed in recent years.

  The electrode including the resin current collector includes a current collector composed of a first current collector element including a first resin and a first conductive material, and a first active material including a first binder on the surface of the current collector. An electrode in which layers are laminated is known (see, for example, Patent Document 6). In Patent Document 6, when the difference in solubility parameter between the first resin and the first binder is 0 to 2.5, the adhesion between the resin current collector and the active material layer is excellent, and the electric resistance of the electrode is reduced. It is disclosed that it can be suppressed.

  However, in Patent Document 6, studies other than the resin and the conductive material among the raw materials used when the resin current collector is manufactured are insufficient. Further, since the resin proposed in Patent Document 6 is an uncrosslinked resin, when a non-aqueous electrolyte secondary battery is manufactured using the resin current collector described in Patent Document 6, the resin is made up of an electrolyte. In some cases, it expanded or dissolved.

  Also known is a conductive composition comprising a polymer component comprising a fluoropolymer that can be suitably used to produce a circuit protection device and a particulate conductive filler dispersed in the polymer component (for example, And Patent Document 7). However, in patent document 7, examination about components other than a fluorine-type polymer and a granular conductive filler was inadequate. Patent Document 7 does not describe obtaining a non-aqueous electrolyte secondary battery electrode using the conductive composition.

Japanese Patent Laid-Open No. 6-172452 JP-A-2005-47275 Japanese Patent Laid-Open No. 9-231977 JP-A-56-133309 JP 2004-200010 A JP 2010-170832 A JP-T 8-512174 Publication

  The present invention has been made in view of the above-mentioned problems of the prior art, and is a conductive cross-linking that is excellent in peel strength between a mixture layer and a current collector when a non-aqueous electrolyte secondary battery electrode is produced. An object is to provide a film (current collector).

  Moreover, it aims at providing the electrode for nonaqueous electrolyte secondary batteries and a nonaqueous electrolyte secondary battery formed using this electroconductive bridge | crosslinking film.

  Furthermore, it aims at providing the manufacturing method of the electroconductive crosslinked film which can manufacture the said electroconductive crosslinked film efficiently.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a conductive crosslinked film formed using a specific vinylidene fluoride resin composition uses the film as a current collector. It was found that when a non-aqueous electrolyte secondary battery electrode was obtained by forming a mixture layer on an electric body, the peel strength between the current collector and the mixture layer was excellent, and the present invention was completed.

  That is, the conductive crosslinked film of the present invention comprises a vinylidene fluoride polymer (a) 40 to 93 parts by weight, conductive carbon black (b) 5 to 25 parts by weight, a crosslinking agent (c) 2 to 30 parts by weight and It is formed by crosslinking a vinylidene fluoride resin composition containing 0 to 5 parts by weight of the lubricant (d) (however, the total of (a) to (d) is 100 parts by weight).

  The vinylidene fluoride resin composition comprises a vinylidene fluoride polymer (a) 40 to 92.9 parts by weight, conductive carbon black (b) 5 to 25 parts by weight, and a crosslinking agent (c) 2 to 30 parts by weight. And it is preferable to contain 0.1-5 weight part of lubricants (d), and it is also preferable that 0.1-5 weight part of fibrous carbon (e) is included.

  The crosslinking is preferably performed by irradiating the vinylidene fluoride resin composition with ionizing radiation, and the ionizing radiation is preferably ultraviolet rays, electron beams, γ rays, or α rays.

  The vinylidene fluoride polymer (a) is preferably a vinylidene fluoride polymer having 70 mol% or more of a structural unit derived from vinylidene fluoride.

  The lubricant (d) is preferably a metal soap lubricant, and the metal soap lubricant is preferably at least one metal soap lubricant selected from calcium stearate and magnesium stearate.

  The electrode for nonaqueous electrolyte secondary batteries of the present invention is formed from the conductive crosslinked film, and a mixture for nonaqueous electrolyte secondary batteries containing a vinylidene fluoride polymer and an electrode active material.

  The negative electrode for nonaqueous electrolyte secondary batteries of the present invention is formed from the conductive cross-linked film, and a negative electrode mixture for nonaqueous electrolyte secondary batteries containing a vinylidene fluoride polymer and a carbon-based negative electrode active material.

  The positive electrode for a nonaqueous electrolyte secondary battery of the present invention is formed from the conductive crosslinked film and a positive electrode mixture for a nonaqueous electrolyte secondary battery containing a vinylidene fluoride polymer and a lithium positive electrode active material.

  The conductive cross-linked film forms a multilayer film having a vinylidene fluoride resin composition layer and an olefin resin layer by co-extrusion of the vinylidene fluoride resin composition and an olefin resin. Obtained by peeling the olefin resin layer of the multilayer film to obtain a film made of the vinylidene fluoride resin composition, and irradiating the film made of the vinylidene fluoride resin composition with ionizing radiation. It is preferred that

  The method for producing a conductive crosslinked film of the present invention comprises a vinylidene fluoride polymer (a) 40 to 93 parts by weight, a conductive carbon black (b) 5 to 25 parts by weight, and a crosslinking agent (c) 2 to 30 parts by weight. The vinylidene fluoride resin composition containing 0 to 5 parts by weight of the lubricant (d) (provided that the total of (a) to (d) is 100 parts by weight) and the olefin resin are coextruded. Step (I) of forming a multilayer film having a vinylidene fluoride resin composition layer and an olefin resin layer, peeling off the olefin resin layer of the multilayer film, and vinylidene fluoride resin composition A step (II) for obtaining a film comprising: a step (III) for irradiating the film comprising the vinylidene fluoride resin composition with ionizing radiation.

  The vinylidene fluoride resin composition comprises a vinylidene fluoride polymer (a) 40 to 92.9 parts by weight, conductive carbon black (b) 5 to 25 parts by weight, and a crosslinking agent (c) 2 to 30 parts by weight. And it is preferable to contain 0.1-5 weight part of lubricants (d), and it is also preferable that the melt flow rate (JIS K7210, 250 degreeC, 2160g load) of the said olefin resin is 1 g / 10min or less.

  The nonaqueous electrolyte secondary battery of the present invention has the nonaqueous electrolyte secondary battery electrode (negative electrode and / or positive electrode) of the present invention.

  The conductive crosslinked film of the present invention is used as a current collector, and when the electrode for a nonaqueous electrolyte secondary battery is produced using the film, the peel strength between the electrode mixture layer and the current collector is increased. Excellent.

  In addition, the conductive cross-linked film of the present invention has excellent N-methyl-2-pyrrolidone (NMP) resistance, low diethyl carbonate (DEC) transmittance, and low volume resistivity, so that it is a nonaqueous electrolyte secondary battery. It can be suitably used as a current collector that constitutes a working electrode.

  Moreover, the manufacturing method of the electroconductive crosslinked film of the present invention is an electroconductive cross-linked film having a thin thickness that can efficiently produce an electroconductive cross-linked film and is difficult to manufacture with a uniform thickness. Even if it exists, it can manufacture suitably.

  Next, the present invention will be specifically described.

  The conductive crosslinked film of the present invention comprises a vinylidene fluoride polymer (a) 40 to 93 parts by weight, a conductive carbon black (b) 5 to 25 parts by weight, a crosslinking agent (c) 2 to 30 parts by weight, and a lubricant. (D) It is formed by crosslinking a vinylidene fluoride resin composition containing 0 to 5 parts by weight (provided that the total of (a) to (d) is 100 parts by weight). The conductive crosslinked film of the present invention can be suitably used as a current collector such as an electrode for a nonaqueous electrolyte secondary battery.

[Vinylidene fluoride polymer (a)]
The vinylidene fluoride polymer (a) is a polymer obtained by using at least vinylidene fluoride as a monomer, and may be a homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride and another monomer. Good. Further, the vinylidene fluoride polymer (a) may be one kind of polymer or two or more kinds of polymers.

  Examples of other monomers include fluorine monomers copolymerizable with vinylidene fluoride, monoesters of unsaturated dibasic acids, and hydrocarbon monomers. Examples of the fluorine-based monomer copolymerizable with vinylidene fluoride include perfluoroalkyl vinyl ethers typified by vinyl fluoride, trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, and perfluoromethyl vinyl ether. . The monoester of unsaturated dibasic acid is preferably one having 5 to 8 carbon atoms, and examples thereof include maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester, and citraconic acid monoethyl ester. Further, examples of the hydrocarbon monomer include ethylene, propylene, 1-butene and the like.

  Of these, hexafluoropropylene is preferred from the viewpoints of electrochemical stability and good processability. In addition, the said other monomer may be used individually by 1 type, and may use 2 or more types.

  The vinylidene fluoride polymer (a) is preferably a vinylidene fluoride polymer having 70 mol% or more of a structural unit derived from vinylidene fluoride from the viewpoint of electrochemical stability and good processability. A vinylidene fluoride polymer having a structural unit derived from vinylidene fluoride of 80 mol% or more is particularly preferable. The vinylidene fluoride polymer (a) is most preferably a homopolymer of vinylidene fluoride from the viewpoint of being more electrochemically stable.

  The method for producing the vinylidene fluoride polymer (a) is not particularly limited, but can be produced by a known production method such as suspension polymerization, emulsion polymerization, solution polymerization or the like. As the production method, aqueous suspension polymerization and emulsion polymerization are preferable from the viewpoint of ease of post-treatment and the like, and aqueous suspension polymerization is particularly preferable.

  A commercially available product may be used as the vinylidene fluoride polymer (a), and for example, KF # 1000 (manufactured by Kureha), Solef 1010 (manufactured by Solvay), and the like can be used.

  The vinylidene fluoride polymer (a) preferably has a melt flow rate (MFR) of 0.6 to 30 g / 10 min measured at 235 ° C. under a load of 5000 g in accordance with ASTM D1238. Within this range, it is preferable because it is easy to obtain a thin film of about 10 to 100 μm as the conductive crosslinked film of the present invention.

[Conductive carbon black (b)]
The conductive carbon black (b) is not particularly limited, and examples of the conductive carbon black (b) include acetylene black, oil furnace black, and thermal black produced by an acetylene thermal decomposition method.

  Further, as the conductive carbon black (b), ketjen black (trade name) is preferably used. Ketjen Black (trade name) is preferable because it has a structure in which graphite crystals are gathered on the surface of hollow shell particles, has a high surface area and a high oil absorption, and can exhibit high electrical conductivity.

The volatile content of the conductive carbon black (b) is usually 1 wt% or less. The dibutyl phthalate (DBP) oil absorption amount of the conductive carbon black (b) is preferably 50 to 800 ml / 100 g, and more preferably 350 to 500 ml / 100 g. If the oil absorption is below the above range, the conductivity may be insufficient, and if it exceeds the above range, the dispersibility in the vinylidene fluoride polymer (a) tends to be poor. Further, BET specific surface area of conductive carbon black (b) is preferably 35~1800m ² / g, more preferably 65~1400m ² / g.

As the conductive carbon black (b), a commercially available product may be used. Ketjen black EC300J (trade name) (manufactured by Ketjen Black International, BET specific surface area 800 m ² / g, DBP oil absorption 365 ml / 100 g, volatilization 0.4 wt%), Ketjen Black EC600JD (trade name) (Ketjen Black International, BET specific surface area 1400 m ² / g, DBP oil absorption 495 ml / 100 g, volatile content 0.5 wt%), etc. it can.

[Crosslinking agent (c)]
Although there is no restriction | limiting in particular as a crosslinking agent (c), It is preferable to use the crosslinking agent which is excellent in the dispersibility with respect to the said vinylidene fluoride polymer (a).

  The crosslinking agent (c) is preferably an unsaturated monomer having two or more ethylenic double bonds. Examples of the crosslinking agent (c) include dimethylol tricyclodecane diacrylate, divinylbenzene, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butyl glycol dimethacrylate, and propylene glycol dimethacrylate. Methacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, allyl methacrylate, allyl acrylate, bisphenol dimethacrylate, bisphenol diacrylate, cycloaliphatic diacrylate, diacrylate Isocyanurate, trimethylolpropane trimethacrylate, triacryl formal, triacryl isocyanurate , Triallyl cyanurate, triallyl isocyanurate, tri (methylallyl) isocyanurate, triallyl phosphite, N, N-diallylacrylamide, 2,4,6-trivinylmethyltrisiloxane, aliphatic triacrylate, pentaerythritol tetra Examples include methacrylate, pentaerythritol tetraacrylate, and aliphatic tetraacrylate.

  As the crosslinking agent (c), triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is more preferable from the viewpoint of crosslinking efficiency, heat resistance, and mechanical properties of the obtained conductive crosslinked film.

[Lubricant (d)]
The lubricant (d) used in the present invention is processed by improving the fluidity and dispersibility of the conductive carbon black (b) when the vinylidene fluoride resin composition is thermoformed into a film. It means a compounding agent added to facilitate the process.

  The lubricant (d) is not particularly limited, and examples thereof include aliphatic hydrocarbon lubricants, higher aliphatic alcohol lubricants, higher fatty acid lubricants, fatty acid amide lubricants, metal soap lubricants, fatty acid ester lubricants, and the like. Can be used. The lubricant (d) is preferably a metal soap lubricant from the viewpoint of compatibility with the vinylidene fluoride polymer (a) and thermal stability.

Examples of the aliphatic hydrocarbon lubricant include C ₁₆ or more liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyethylene wax and partial oxides thereof, fluoride, chloride, and the like.

  Examples of the higher aliphatic alcohol lubricant include higher aliphatic alcohols such as stearyl alcohol and behenyl alcohol.

Examples of the higher fatty acid-based lubricant include C ₁₆ or higher fatty acids such as stearic acid and arachidic acid.

  Examples of the fatty acid amide lubricant include stearic acid amide, N, N′-methylenebisamide, erucic acid amide and the like.

  As the metal soap lubricant, a metal soap lubricant usually derived from a fatty acid having 12 to 30 carbon atoms and a metal (excluding sodium and potassium) is used. Examples of the fatty acid include stearic acid, lauric acid, ricinoleic acid, octylic acid, and the like. Examples of the metal include magnesium, calcium, lithium, barium, zinc, and aluminum.

  Examples of the metal soap lubricant include barium stearate, calcium stearate, magnesium stearate, lithium stearate, stearic acid from the viewpoint of moldability of the vinylidene fluoride resin composition and dispersibility of the conductive carbon black (b). Zinc and aluminum stearate are preferable, and calcium stearate and magnesium stearate are more preferable.

  Examples of the fatty acid ester lubricant include ethylene glycol monostearate and glycerin monostearate.

  Note that the lubricant (d) may be used alone or in combination of two or more.

[Vinylidene fluoride resin composition]
In order to obtain the conductive crosslinked film of the present invention, a vinylidene fluoride resin composition containing the above (a) to (d) is used.

  The vinylidene fluoride resin composition comprises 40 to 93 parts by weight of the vinylidene fluoride polymer (a), 5 to 25 parts by weight of conductive carbon black (b), 2 to 30 parts by weight of a crosslinking agent (c) and , Containing 0-5 parts by weight of lubricant (d). The total of (a) to (d) is 100 parts by weight. In addition, the vinylidene fluoride resin composition contains 40 to 92.9 parts by weight of the vinylidene fluoride polymer (a), 5 to 25 parts by weight of conductive carbon black (b), and 2 to 30 crosslinking agents (c). It is preferable to contain 0.1-5 weight part of weight parts and lubricant (d).

  The vinylidene fluoride resin composition is excellent in moldability because conductive carbon black (b) is dispersed in the vinylidene fluoride polymer (A) and usually contains a lubricant (d). Moreover, since it contains a crosslinking agent (c), it is possible to perform crosslinking.

  The vinylidene fluoride resin composition may not contain the lubricant (d), but preferably contains 0.1 to 5 parts by weight. Even when the vinylidene fluoride resin composition does not contain a lubricant (d), a nonaqueous electrolyte secondary battery was manufactured by lengthening the kneading zone of the kneader or optimizing the kneading conditions. In this case, it is possible to produce a conductive crosslinked film having excellent peel strength between the mixture layer and the current collector, but when the lubricant (d) is used in the above range, the lubricant (d) is not used. Compared with, a conductive crosslinked film can be easily obtained.

  The vinylidene fluoride resin composition comprises 50 to 90.9 parts by weight of the vinylidene fluoride polymer (a), 4 to 20 parts by weight of conductive carbon black (b), and 5 to 29 parts by weight of a crosslinking agent (c). And 0.1 to 1 part by weight of the lubricant (d) is more preferable from the viewpoint of resistance stability of the conductive crosslinked film of the present invention.

  The vinylidene fluoride resin composition may contain components other than the above (a) to (d). Examples of components other than the above (a) to (d) contained in the vinylidene fluoride resin composition include fibrous carbon (e), metal fine powder, and metal oxide.

  The fibrous carbon (e) is carbon having a fibrous shape, and usually has a ratio (aspect ratio) of the shortest diameter to the longest diameter of 5 to 1000. Although there is no limitation in particular as the fiber length of fibrous carbon (e), Usually, it is 5-30 micrometers, Preferably it is 10-20 micrometers.

  When the said vinylidene fluoride resin composition contains fibrous carbon (e), there exists a tendency for the rigidity of the conductive crosslinked film obtained to improve, and it is preferable.

  In the conductive crosslinked film of the present invention, the conductive carbon black (b) and the fibrous carbon (e) function as a conductive agent.

  In addition, when the said vinylidene fluoride resin composition contains fibrous carbon (e), it is 0.1-5 weight part with respect to a total of 100 weight part of (a)-(d), Preferably it is 0. 0.1 to 3 parts by weight.

  In addition, the said vinylidene fluoride resin composition is obtained by mixing said (a)-(d) and the other component contained arbitrarily. The mixing is performed by a known method.

[Conductive cross-linked film]
The conductive crosslinked film of the present invention is formed by crosslinking the vinylidene fluoride resin composition.

  The conductive cross-linked film of the present invention has excellent N-methyl-2-pyrrolidone (NMP) resistance, low diethyl carbonate (DEC) transmittance, and low volume resistivity, and therefore can be used as a current collector. . In particular, the conductive crosslinked film of the present invention can be suitably used as a current collector constituting an electrode for a nonaqueous electrolyte secondary battery.

  The thickness of the conductive crosslinked film used in the present invention is usually 10 to 200 μm, preferably 20 to 180 μm, more preferably 30 to 50 μm.

  In the conductive crosslinked film of the present invention, since the resin component constituting the film is mainly formed from the vinylidene fluoride polymer (a) and the crosslinking agent (c), N-methyl-2-pyrrolidone resistance ( NMP) is excellent and diethyl carbonate (DEC) transmittance is low.

  The NMP resistance of the conductive crosslinked film can be measured by the method described in Examples below and (5) gel fraction, and the gel fraction is preferably 80 to 99%, 88 More preferably, it is -97%. When the gel fraction is within the above range, the electroconductive crosslinked film is excellent in NMP resistance, and it is preferable because the elution of the resin is small when the secondary battery mixture is applied to the film and dried.

  Further, the DEC transmittance of the conductive cross-linked film can be measured by the method described in Examples below and (4) DEC transmittance, and the DEC transmittance is preferably 0 to 10%. 0 to 5% is more preferable. When the DEC transmittance is within the above range, in the non-aqueous electrolyte secondary battery having the conductive cross-linked film of the present invention as a current collector, it is possible to suppress the electrolyte from passing through the current collector.

  Moreover, since the electroconductive crosslinked film of this invention contains electroconductive carbon black (b) and arbitrarily contains fibrous carbon (e), it is excellent in electroconductivity and has a low volume resistivity.

  The volume resistivity of the conductive cross-linked film can be measured by the method described in Examples below, (3) Volume resistivity, and the volume resistivity is preferably 10 Ωcm or less, preferably 8 Ωcm or less. More preferably. The lower the volume resistivity, the better. The lower limit of the volume resistivity is not particularly limited, but is usually 0.1 Ωcm or more.

  The method for producing the conductive crosslinked film of the present invention is not particularly limited. However, since it is difficult to form a film after crosslinking the vinylidene fluoride resin composition, the vinylidene fluoride is usually used. After the resin composition is molded into a film, it is crosslinked to obtain a conductive crosslinked film.

  The method for forming the vinylidene fluoride resin composition into a film is not particularly limited. For example, the vinylidene fluoride resin composition is pelletized by a melt extrusion method or the like, and the resulting pellet is melted. Examples of the method include forming into a film by a molding method such as extrusion molding, injection molding, and press molding.

  As a method of melt-extruding the pellets, for example, the pellets are melted with a single-screw or twin-screw melt extruder, and are extruded into a film form by extrusion through a T-die or the like under general extrusion conditions. Is mentioned.

  When the vinylidene fluoride resin composition is formed into a thin film, the melt extrusion generally tends to make it difficult to make the film thickness uniform. Therefore, when a vinylidene fluoride resin composition is formed into a thin film, for example, a film having a thickness of 10 to 150 μm, it is formed as a multilayer film by coextrusion with another thermoplastic resin. It is preferable. In addition, when it forms as a multilayer film, it is necessary to peel the layer formed from another thermoplastic resin, but this peeling may be performed before bridge | crosslinking or after bridge | crosslinking. From the viewpoint of avoiding decomposition due to irradiation with radiation, it is preferable to carry out before crosslinking.

  Examples of the another thermoplastic resin include an olefin resin, polycarbonate, polyethylene terephthalate, and the like, and an olefin resin that is easily peeled off from a layer formed from the vinylidene fluoride resin composition is preferable.

  Examples of the olefin resin include high density polyethylene (HDPE) and polypropylene (PP).

  The other thermoplastic resin preferably has a melt flow rate (MFR) (JIS K7210, 250 ° C., 2160 g load) of 1 g / 10 min or less from the viewpoint of melt tension during molding. It is more preferably 10 min or less, and particularly preferably 0.1 g / 10 min or less. Although there is no limitation in particular as a minimum of MFR, Usually, a thermoplastic resin whose MFR is 0.015 g / 10min or more is used.

  When the conductive crosslinked film of the present invention is produced, crosslinking is performed as described above, and the crosslinking is applied to a vinylidene fluoride resin composition, preferably a vinylidene fluoride resin composition formed into a film. It is preferable to carry out by irradiating with ionizing radiation.

  That is, as a method for producing the conductive cross-linked film of the present invention, the vinylidene fluoride resin composition and the olefin resin are coextruded to form a vinylidene fluoride resin composition layer and an olefin resin layer. A step (I) of forming a multilayer film comprising: a step (II) of obtaining a film comprising a vinylidene fluoride resin composition by peeling off an olefin resin layer of the multilayer film, and the vinylidene fluoride resin composition The manufacturing method of the electroconductive crosslinked film which has process (III) which irradiates ionizing radiation to the film which consists of a thing is preferable. The production method can efficiently produce a conductive crosslinked film, and can be suitably produced even with a thin conductive crosslinked film that is difficult to produce with a uniform thickness. it can.

  As the ionizing radiation, ultraviolet rays, electron beams, γ rays or α rays are preferable, and γ rays are most preferable from the viewpoint of crosslinking efficiency, uniformity of crosslinking, and the like.

  In addition, when γ-rays are irradiated as ionizing radiation, the irradiation dose is usually 10 to 300 kGy, preferably 50 to 200 kGy. If the irradiation dose is too small, crosslinking may not occur sufficiently. If the irradiation dose is too high, the resulting conductive crosslinked film tends to become brittle, so the above range is preferable.

[Electrode for non-aqueous electrolyte secondary battery]
The electrode for a nonaqueous electrolyte secondary battery of the present invention is an electrode having the conductive crosslinked film as a current collector, and is an electrode formed from the conductive crosslinked film and a mixture for a nonaqueous electrolyte secondary battery It is.

  As the mixture for the nonaqueous electrolyte secondary battery, a mixture containing a vinylidene fluoride polymer and an electrode active material is used. By using a mixture containing a vinylidene fluoride polymer, the mixture for a non-aqueous electrolyte secondary battery of the present invention is excellent in peel strength between the conductive crosslinked film and the mixture layer.

  The electrode for a nonaqueous electrolyte secondary battery of the present invention can be used as a negative electrode or a positive electrode. When using a nonaqueous electrolyte secondary battery electrode as a negative electrode, that is, when obtaining a nonaqueous electrolyte secondary battery negative electrode, a nonaqueous electrolyte secondary battery negative electrode mixture is used as a nonaqueous electrolyte secondary battery mixture. Is used. Moreover, when using the electrode for nonaqueous electrolyte secondary batteries as a positive electrode, ie, when obtaining the positive electrode for nonaqueous electrolyte secondary batteries, as a mixture for nonaqueous electrolyte secondary batteries, the positive electrode for nonaqueous electrolyte secondary batteries Use a mixture.

  In addition, the electrode for nonaqueous electrolyte secondary batteries of this invention is a case where it is a case where it uses as a negative electrode or a positive electrode, As a mixture, the mixture containing a vinylidene fluoride polymer is used.

  The vinylidene fluoride-based polymer contained in the mixture is a polymer that acts as a binder resin, and any resin having a structural unit derived from vinylidene fluoride is not particularly limited. Examples thereof include polymers, copolymers of vinylidene fluoride and other monomers, modified products of homopolymers of vinylidene fluoride, and modified products of copolymers of vinylidene fluoride and other monomers. These resins are usually used alone or in combination of two or more.

  Examples of the other monomer include a carboxyl group-containing monomer, a carboxylic acid anhydride group-containing monomer, a fluorine-containing monomer excluding vinylidene fluoride, and an α-olefin. As another monomer, you may use individually by 1 type, or may be used by 2 or more types.

  Examples of the carboxyl group-containing monomer include acrylic acid, maleic acid, citraconic acid, maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester, citraconic acid monoethyl ester, and the like. Maleic acid, citraconic acid Maleic acid monomethyl ester and citraconic acid monomethyl ester are preferred.

  Examples of the carboxylic acid anhydride group-containing monomer include maleic anhydride and citraconic anhydride.

  Examples of the fluorine-containing monomer excluding vinylidene fluoride include vinyl fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, and hexafluoropropylene.

  Examples of the α-olefin include ethylene, propylene, and 1-butene.

  The copolymer of vinylidene fluoride and other monomers is preferably a copolymer of vinylidene fluoride and maleic acid monomethyl ester, a copolymer of vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester, or the like. It is done.

  The method for obtaining the vinylidene fluoride polymer contained in the mixture is not particularly limited, and for example, it can be obtained by a polymerization method such as suspension polymerization, emulsion polymerization, or solution polymerization.

  In addition, a modified product of a homopolymer of vinylidene fluoride or a copolymer of a copolymer of vinylidene fluoride and another monomer includes the homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride and another monomer. The polymer can be obtained by modification. As the modification, it is preferable to use a monomer having a carboxyl group or a carboxylic anhydride group such as maleic acid and maleic anhydride.

  The vinylidene fluoride polymer used in the present invention preferably has 50 mol% or more of structural units derived from vinylidene fluoride (provided that all the structural units are 100 mol%).

  A commercially available product may be used as the vinylidene fluoride polymer.

  The mixture for a non-aqueous electrolyte secondary battery used for producing the electrode for the non-aqueous electrolyte secondary battery of the present invention includes the vinylidene fluoride polymer and the electrode active material, and usually includes an organic solvent. . The mixture may contain other components. Examples of the other components include conductive additives such as carbon fibers, pigment dispersants, polymers other than vinylidene fluoride polymers, and the like. You may go out. Examples of the polymer other than the vinylidene fluoride polymer include styrene butadiene rubber and polyacrylonitrile.

  In order to obtain the negative electrode for nonaqueous electrolyte secondary batteries, the negative electrode active material is used as the electrode active material contained in the mixture for nonaqueous electrolyte secondary batteries, and to obtain the positive electrode for nonaqueous electrolyte secondary batteries. A positive electrode active material is used for.

  Examples of the negative electrode active material include a carbon-based negative electrode active material composed of a carbon material, a metal-based negative electrode active material composed of a metal / alloy material or a metal oxide, and among them, a carbon-based negative electrode active material is preferable.

  As the carbon-based negative electrode active material, artificial graphite, natural graphite, non-graphitizable carbon, graphitizable carbon, or the like is used. Moreover, the said carbon material may be used individually by 1 type, or may use 2 or more types.

  When such a carbon-based negative electrode active material is used, the energy density of the battery can be increased.

  The artificial graphite can be obtained, for example, by carbonizing an organic material, heat-treating it at a high temperature, pulverizing and classifying it. As the artificial graphite, MAG series (manufactured by Hitachi Chemical Co., Ltd.), MCMB (manufactured by Osaka Gas) and the like are used.

  The non-graphitizable carbon can be obtained, for example, by firing a material derived from petroleum pitch at 1000 to 1500 ° C. As the non-graphitizable carbon, Carbotron P (made by Kureha) or the like is used.

The specific surface area of the negative active material is preferably 1 to 10 m ² / g, and more preferably 2 to 6 m ² / g. The specific surface area of the negative electrode active material can be determined by a nitrogen adsorption method.

As the positive electrode active material, a lithium-based positive electrode active material containing at least lithium is preferable. The lithium-based positive active material for _{example, LiCoO 2, LiNi x Co 1} -x O 2 (0 ≦ x ≦ 1) Formula Limy ₂ (M such is, Co, Ni, Fe, Mn , Cr, V-like At least one kind of transition metal: Y is a chalcogen element such as O and S), a composite metal oxide having a spinel structure such as LiMn ₂ O ₄ , and an olivine-type lithium compound such as LiFePO ₄ It is done. In addition, you may use a commercial item as said positive electrode active material.

  Examples of the organic solvent usually contained in the mixture for non-aqueous electrolyte secondary batteries include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, and hexamethylphosphoamide. , Dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, trimethyl phosphate, etc., and N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide is preferably used. . Moreover, the organic solvent may be used alone or in combination of two or more.

  The mixture for a non-aqueous electrolyte secondary battery is preferably 0.5 to 15 parts by weight of the vinylidene fluoride polymer per 100 parts by weight in total of the vinylidene fluoride polymer and the electrode active material. The amount is preferably 1 to 10 parts by weight, and the active material is preferably 85 to 99.5 parts by weight, and more preferably 90 to 99 parts by weight. Further, when the total of the vinylidene fluoride polymer and the electrode active material is 100 parts by weight, the organic solvent is preferably 20 to 300 parts by weight, and more preferably 50 to 200 parts by weight.

  As a method for preparing the non-aqueous electrolyte secondary battery mixture, the components in the mixture may be mixed so as to form a uniform slurry, and the order of mixing is not particularly limited.

  The electrode for a nonaqueous electrolyte secondary battery of the present invention is usually obtained by applying and drying the mixture for a nonaqueous electrolyte secondary battery on a conductive cross-linked film as a current collector, and a current collector, And a layer formed from a nonaqueous electrolyte secondary battery mixture.

  In the present invention, a layer formed from a mixture for a nonaqueous electrolyte secondary battery, which is formed by applying and drying a mixture for a nonaqueous electrolyte secondary battery on a current collector, a mixture layer I write.

In addition, it is preferable that the coating amount of the mixture for nonaqueous electrolyte secondary batteries in the said application | coating is the range from which the weight of the mixture layer after application | coating and drying will be 100-300 g / m < ² >, 130-200 g More preferably, it is in the range of / m ² .

  When manufacturing the electrode for nonaqueous electrolyte secondary batteries of the present invention, the mixture for nonaqueous electrolyte secondary batteries is applied to at least one surface, preferably both surfaces of the current collector. The method for coating is not particularly limited, and examples thereof include a method using a bar coater, a die coater, or a comma coater.

  Moreover, as drying performed after apply | coating, it is normally performed for 1 to 300 minutes at the temperature of 50-150 degreeC. Moreover, the pressure at the time of drying is not particularly limited, but it is usually carried out under atmospheric pressure or reduced pressure.

  Further, heat treatment may be performed after drying. When performing heat processing, it is normally performed for 1 to 300 minutes at the temperature of 100-250 degreeC. In addition, although the temperature of heat processing overlaps with the said drying, these processes may be a separate process and the process performed continuously.

  Further, press processing may be performed. When performing a press process, it is normally performed at 1-200 MPa-G. It is preferable to perform the press treatment because the electrode density can be improved.

  By the above method, the electrode for nonaqueous electrolyte secondary batteries of this invention can be manufactured. In addition, as a layer structure of the electrode for nonaqueous electrolyte secondary batteries, when the mixture for nonaqueous electrolyte secondary batteries is applied to one surface of the current collector, the layer structure of the mixture layer / current collector is Yes, when the mixture for a non-aqueous electrolyte secondary battery is applied on both sides of the current collector, it has a three-layer structure of a mixture layer / current collector / mixture layer.

  Since the electrode for a nonaqueous electrolyte secondary battery of the present invention is excellent in the peel strength between the current collector and the mixture layer by using the conductive cross-linked film and the mixture for nonaqueous electrolyte secondary batteries, the electrode Even when the non-aqueous electrolyte secondary battery having the above is used for applications where vibration, impact, or the like is applied, it is possible to suppress separation of the current collector and the mixture layer. Moreover, since it is excellent in peeling strength, it is preferable for cracking and peeling to occur in the electrode in the process of pressing, slitting, winding and the like when manufacturing the electrode, leading to improvement in productivity.

[Nonaqueous electrolyte secondary battery]
The non-aqueous electrolyte secondary battery of the present invention has the non-aqueous electrolyte secondary battery electrode. The nonaqueous electrolyte secondary battery of the present invention may have the negative electrode for a nonaqueous electrolyte secondary battery, may have the positive electrode for a nonaqueous electrolyte secondary battery, or has both. May be.

  As the nonaqueous electrolyte secondary battery of the present invention, it is sufficient that at least one of the negative electrode and the positive electrode has the electrode for a nonaqueous electrolyte secondary battery, and other members, for example, a separator is not particularly limited, A well-known thing can be used.

  The nonaqueous electrolyte secondary battery of the present invention can be used for various applications. Since the nonaqueous electrolyte secondary battery of the present invention is excellent in the peel strength between the current collector and the mixture layer by using the electrode for a nonaqueous electrolyte secondary battery as an electrode constituting the battery, Even when the nonaqueous electrolyte secondary battery of the invention is used for applications in which vibration, impact, etc. are applied, it is possible to suppress separation of the current collector and the mixture layer. For this reason, the nonaqueous electrolyte secondary battery of the present invention can be suitably used as a power source for a hybrid car, an electric vehicle or the like to which vibration or impact is applied when used.

  EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by these.

[Production Example 1] (Production of polar group-containing vinylidene fluoride polymer (A))
An autoclave with an internal volume of 2 liters was charged with 1040 g of ion exchange water, 0.8 g of methyl cellulose, 2.5 g of ethyl acetate, 4 g of diisopropyl peroxydicarbonate, 396 g of vinylidene fluoride and 4 g of maleic acid monomethyl ester, and suspended at 28 ° C. for 47 hours. Turbid polymerization was performed. The maximum pressure during this period reached 4.2 MPa.

  After completion of the polymerization, the polymer slurry was dehydrated, washed with water and dried at 80 ° C. for 20 hours to obtain a powdered polar group-containing vinylidene fluoride polymer (A) containing a carboxyl group as a polar group.

  The polymerization yield was 90% by weight, and the inherent viscosity of the obtained polar group-containing vinylidene fluoride polymer (A) was 1.1 dl / g.

[Production Example 2] (Production of polyvinylidene fluoride (B))
An autoclave with an internal volume of 2 liters is charged with 1100 g of ion-exchanged water, 0.2 g of methylcellulose, 2.2 g of diisopropyl peroxydicarbonate, 3.7 g of ethyl acetate, and 430 g of vinylidene fluoride, and suspension polymerization at 26 ° C. for 18.5 hours. Went. The maximum pressure during this period reached 4.1 MPa.

  After the polymerization was completed, the polymer slurry was dehydrated, washed with water, and dried at 80 ° C. for 20 hours to obtain powdered polyvinylidene fluoride (B).

  The polymerization yield was 90% by weight, and the inherent viscosity of the obtained polyvinylidene fluoride (B) was 2.0 dl / g.

[Example 1]
7.9 kg of polyvinylidene fluoride (vinylidene fluoride homopolymer, hereinafter also referred to as PVDF) (KF # 1000 (trade name), manufactured by Kureha, MFR = 8.8 g / 10 min (ASTM D1238, 235 ° C., 5000 g load) )) 1 kg ketjen black EC300J (trade name) (manufactured by ketjen black international, BET specific surface area 800 m ² / g, DBP oil absorption 365 ml / 100 g, volatile content 0.4 wt%), 1 kg triallyl isocyanurate (Hereinafter also referred to as TAIC.) 10 g of calcium stearate was mixed with a mixer (super mixer).

  The obtained mixture was pelletized by a twin-screw kneader (Toshiki Machine TEM26SS).

  The obtained pellets and high density polyethylene (hereinafter also referred to as HDPE) (Nippon Polyethylene, Novatec HF313 (trade name), MFR = 0.05 g / 10 min (JIS K7210, 250 ° C., 2160 g load) Extrusion speed of 2 m using a manifold two-layer T die and two single-screw melt extruders (for surface lamination: PEX40-28H made by Pla Giken Co., Ltd., for back lamination: PEX30-24 made by Pla Giken Co., Ltd.) A film having a surface layer (thickness 50 μm) formed from the pellets and a back layer (thickness 100 μm) formed from the HDPE was molded by coextrusion at 250 ° C./min.

  After cooling the film with a cast roll, the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (1).

  The obtained film was irradiated with γ rays (100 kGy) to obtain a conductive crosslinked film (1) having a thickness of 50 μm.

[Example 2]
6.99 kg of PVDF, 2 kg of acetylene black (Denka Black: granular, Denki Kagaku Kogyo Co., Ltd.), 1 kg of TAIC, and 10 g of calcium stearate were mixed with a mixer (super mixer).

  The obtained mixture was pelletized with a twin-screw kneader (Toshiki Machine TEM26SS).

  In the same manner as in Example 1, the obtained pellet and HDPE (Novatech HF313 (trade name)), a multi-manifold two-layer T-die and two single-screw melt extruders (for front surface lamination and back surface lamination) Was used to form a film having a surface layer (thickness 50 μm) formed from the pellets and a back layer (thickness 100 μm) formed from the HDPE.

  After cooling the film with a cast roll, the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (2).

  The obtained film was irradiated with γ rays (100 kGy) to obtain a conductive crosslinked film (2) having a thickness of 50 μm.

Example 3
7.79 kg of PVDF, 1 kg of ketjen black EC300J (trade name), 200 g of vapor grown carbon fiber VGCF (trade name) (manufactured by Showa Denko, average fiber diameter of 150 nm, average fiber length of 10 to 20 μm, aspect ratio of 10 to 10 500) 1 kg of TAIC and 10 g of calcium stearate were mixed with a mixer (super mixer).

  The obtained mixture was pelletized with a twin-screw kneader (Toshiki Machine TEM26SS).

  In the same manner as in Example 1, the obtained pellet and HDPE (Novatech HF313 (trade name)), a multi-manifold two-layer T-die and two single-screw melt extruders (for front surface lamination and back surface lamination) Was used to form a film having a surface layer (thickness 50 μm) formed from the pellets and a back layer (thickness 100 μm) formed from the HDPE.

  After cooling the film with a cast roll, the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (3).

  The obtained film was irradiated with γ rays (100 kGy) to obtain a conductive crosslinked film (3) having a thickness of 50 μm.

Example 4
8.19kg PVDF, 0.8kg Ketjen Black EC600JD (trade name) (Ketjen Black International, BET specific surface area 1400m ² / g, DBP oil absorption 495ml / 100g, volatile content 0.5wt%), 1kg TAIC and 10 g of calcium stearate were mixed with a mixer (super mixer).

  The obtained mixture was pelletized with a twin-screw kneader (Toshiki Machine TEM26SS).

  In the same manner as in Example 1, the obtained pellet and HDPE (Novatech HF313 (trade name)), a multi-manifold two-layer T-die and two single-screw melt extruders (for front surface lamination and back surface lamination) Was used to form a film having a surface layer (thickness 50 μm) formed from the pellets and a back layer (thickness 100 μm) formed from the HDPE.

  After cooling the film with a cast roll, the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (4).

  The obtained film was irradiated with γ rays (100 kGy) to obtain a conductive crosslinked film (4) having a thickness of 50 μm.

Example 5
7.9 kg of PVDF, 1 kg of ketjen black EC300J (trade name), 1 kg of TAIC, and 10 g of calcium stearate were mixed in a mixer (super mixer).

  The obtained mixture was pelletized with a twin-screw kneader (Toshiki Machine TEM26SS).

  In the same manner as in Example 1, the obtained pellet and HDPE (Novatech HF313 (trade name)), a multi-manifold two-layer T-die and two single-screw melt extruders (for front surface lamination and back surface lamination) Was used to form a film having a surface layer (thickness 50 μm) formed from the pellets and a back layer (thickness 100 μm) formed from the HDPE.

  After cooling the film with (cast roll), the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (5).

  The obtained film was irradiated with γ rays (200 kGy) to obtain a conductive crosslinked film (5) having a thickness of 50 μm.

Example 6
7.19 kg of PVDF, 0.8 kg of ketjen black EC600JD (trade name), 2 kg of TAIC, and 10 g of calcium stearate were mixed in a mixer (super mixer).

  The obtained mixture was pelletized with a twin-screw kneader (Toshiki Machine TEM26SS).

  In the same manner as in Example 1, the obtained pellets and HDPE (Novatech HF313 (trade name)) were combined with a multi-manifold two-layer T-die and two uniaxial melt extruders (for front surface lamination and back surface lamination). The film having a surface layer (thickness: 50 μm) formed from the pellets and a back layer (thickness: 100 μm) formed from the HDPE was molded by coextrusion.

  After cooling the film with a cast roll, the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (6).

  The obtained film was irradiated with γ rays (100 kGy) to obtain a conductive crosslinked film (6) having a thickness of 50 μm.

[Comparative Example 1]
8.9 kg polyphenylene sulfide (hereinafter also referred to as PPS) W316 (trade name), (manufactured by Kureha, melt viscosity 160 Pa · s (310 ° C., 1200 s ⁻¹ )), 1 kg ketjen black EC300J (trade name), 10 g of calcium stearate was mixed with a mixer (super mixer).

  The obtained mixture was pelletized with a twin-screw kneader (Toshiki Machine TEM26SS).

  In the same manner as in Example 1, the obtained pellets and HDPE (Novatech HF313 (trade name)) were combined with a multi-manifold two-layer T-die and two uniaxial melt extruders (for front surface lamination and back surface lamination). The film having a surface layer (thickness: 50 μm) formed from the pellets and a back layer (thickness: 100 μm) formed from the HDPE was molded by coextrusion.

  After cooling the film with a cast roll, the back layer (HDPE layer) was peeled off from the film to obtain a conductive film (c1) having a thickness of 50 μm.

  The physical properties of the conductive crosslinked films (1) to (6) and the conductive film (c1) were measured by the following methods.

(1) Thickness The thickness of each of the conductive crosslinked films (1) to (6) and the conductive film (c1) was measured using a digital dial gauge (manufactured by Ono Sokki: DG-925).

(2) Tensile strength Tensile strength of the conductive crosslinked films (1) to (6) and the conductive film (c1) was measured by the following method.

  A trouser-shaped test piece having a width of 10 mm and a length of 100 mm was obtained from each of the conductive crosslinked films (1) to (6) and the conductive film (c1).

  About each test piece, tensile strength was measured at a measurement speed of 50 mm / min using Autograph AGS-J (load 1 kN).

(3) Volume resistivity About the said electroconductive bridge | crosslinking films (1)-(6) and the electroconductive film (c1), the volume resistivity was measured with the following method.

  For each of the conductive crosslinked films (1) to (6) and the conductive film (c1), a Loresta GP MCP-T610 (manufactured by Mitsubishi Chemical) (probe: ASP (4-terminal method)) and a condition for an application time of 10 min The volume resistivity was measured.

(4) DEC transmittance The DEC (diethyl carbonate) transmittance of the conductive crosslinked films (1) to (6) and the conductive film (c1) was determined by the following method.

  Each of the conductive cross-linked films (1) to (6) and the conductive film (c1) is cut into two 70 × 70 mm squares, the two cut out films are overlapped, and three sides are used using a heat sealer, A bag was prepared by heat-sealing with a seal width of 10 mm. After adding 2 ml of DEC to the bag, the opening was heat sealed with a heat sealer with a seal width of 10 mm to obtain a bag with DEC.

  The DEC transmittance was determined from the change in weight of the DEC bag before and after being left for 400 hours at room temperature.

(5) Gel fraction About the said electroconductive bridge | crosslinking films (1)-(6) and the electroconductive film (c1), the gel fraction was calculated | required with the following method.

  The conductive crosslinked films (1) to (6) and the conductive film (c1) were each cut out with a scissors to obtain a 5 g sample.

  Each 5 g sample was weighed into a flask and 195 g solvent (NMP) was added to the flask to obtain a sample solution. The flask containing the sample solution was heated in the hot water bath (60 ° C.) for 1 hour.

  The heated sample solution was passed over a 20 mesh wire mesh immediately after heating. The gel remaining on the wire mesh was dried, and the obtained solid was weighed to determine the gel fraction.

  Example, amount of conductive agent used in obtaining conductive cross-linked films (1) to (6) and conductive film (c1) obtained in Comparative Examples, cross-linking agent addition amount, γ-ray irradiation amount, and The evaluation results of the physical properties of the film are shown in Table 1.

  Note that the amount of the conductive agent and the amount of the crosslinking agent added in Table 1 were 100 wt% of all components used in obtaining the mixture.

Example 7
Non-graphitizable carbon (manufactured by Kureha, Carbotron P, specific surface area 3.5 to ⁵ m ² / g) 92 parts by weight, polar group-containing vinylidene fluoride polymer (A) 6 parts by weight, gas phase method as a conductive aid Carbon fiber VGCF (manufactured by Showa Denko) and 2 parts by weight of N-methyl-2-pyrrolidone (NMP) for dilution were mixed to prepare a solid content concentration of 52% by weight, and a kneader (manufactured by Shinky Corp .; AR- 250) was kneaded for 5 minutes to obtain a negative electrode mixture (A) for a non-aqueous electrolyte secondary battery.

Uniformly mix the negative electrode mixture (A) for the non-aqueous electrolyte secondary battery with a bar coater on the conductive crosslinked film (1) so that the weight of the mixture layer after drying is 150 g / m ^2. After coating and drying at 120 ° C. in a gear oven, pressing was performed at 40 MPa-G to obtain an electrode (negative electrode) having a mixture layer density of 1.7 g / cm ³ .

[Examples 8 to 12]
Except that the conductive crosslinked film (1) was replaced with the conductive crosslinked films (2) to (6), the same procedure as in Example 7 was performed, and the density of the mixture layer was 1.7 g / cm ³ ( Negative electrode) was obtained.

[Comparative Example 2]
The negative electrode mixture (A) for a non-aqueous electrolyte secondary battery similar to that in Example 7 was dried using a bar coater on a rolled copper foil having a thickness of 10 μm so that the weight of the mixture layer after drying was 150 g / m ² . After uniformly coating and drying at 120 ° C. in a gear oven, pressing was performed at 40 MPa-G to obtain an electrode (negative electrode) having a mixture layer density of 1.7 g / cm ³ .

[Comparative Example 3]
Non-graphitizable carbon (Kureha, Carbotron P, specific surface area 3.5 to ⁵ m ² / g) 95 parts by weight, styrene butadiene rubber suspension (manufactured by Nippon Zeon, BM400B, 2 parts by weight as rubber), carboxymethylcellulose (CMC) Aqueous solution (manufactured by Daicel Chemical Industries, product number 1160, 1 part by weight as CMC component), 2 parts by weight of vapor grown carbon fiber VGCF (manufactured by Showa Denko) as a conductive additive and water for dilution are mixed to obtain a solid content The concentration was adjusted to 55% by weight, and the mixture was kneaded for 5 minutes using a kneader (manufactured by Shinky Corp .; AR-250) to obtain a negative electrode mixture (B) for a non-aqueous electrolyte secondary battery.

Apply the negative electrode mixture (B) for the non-aqueous electrolyte secondary battery uniformly to a rolled copper foil having a thickness of 10 μm using a bar coater so that the weight of the mixture layer after drying is 150 g / m ^2. After drying at 120 ° C. in a gear oven, pressing was performed at 40 MPa-G to obtain an electrode having a mixture layer density of 1.6 g / cm ³ .

[Reference Example 1]
Except that the rolled copper foil having a thickness of 10 μm was replaced with the conductive crosslinked film (1), the same procedure as in Comparative Example 3 was performed to obtain an electrode (negative electrode) having a mixture layer density of 1.7 g / cm ^3. It was.

[Comparative Example 4]
Except having replaced the electroconductive crosslinked film (1) with the electroconductive film (c1), it carried out similarly to Example 7, and obtained the electrode (negative electrode) whose density of a mixture layer is 1.7 g / cm < ³ >. .

Example 13
94 parts by weight of LiCoO ₂ (manufactured by Nippon Chemical Industry Co., Ltd .; “Cellseed C-10N”), Ketjen Black ECP (trade name) as carbon black (Ketjen Black International, Ketjen Black EC300J powder, 200 3 parts by weight of mesh and 75 μm pass (98% or more), 3 parts by weight of polyvinylidene fluoride (B) and NMP are mixed to prepare a solid content concentration of 67%, and a kneader (manufactured by Shinky Corp .; AR-250) Was kneaded for 5 minutes to obtain a positive electrode mixture (C) for a non-aqueous electrolyte secondary battery. The positive electrode mixture (C) for the nonaqueous electrolyte secondary battery was applied to the conductive crosslinked film (1) using a coating apparatus (manufactured by Toyo System Co., Ltd .; TOSMAC 100WI-E), and 0.3 m After drying at 130 ° C. and a wind speed setting scale of 50% at a line speed (drying furnace line length = 1 m) per minute, pressing is performed at 40 MPa-G, and the density of the mixture layer is 3.3 g / cm ^3. An electrode (positive electrode) was obtained.

[Examples 14 to 18]
Except having replaced the electroconductive crosslinked film (1) with the electroconductive crosslinked films (2) to (6), the same procedure as in Example 13 was performed, and the density of the mixture layer was 3.4 g / cm ³ ( Positive electrode) was obtained.

[Comparative Example 5]
The same positive electrode mixture (C) for non-aqueous electrolyte secondary batteries as in Example 13 was applied to a rolled aluminum foil having a thickness of 10 μm using a coating apparatus (manufactured by Toyo System Co., Ltd .; TOSMAC 100WI-E). After drying at a line speed of 0.3 m / min (drying furnace line length = 1 m) at 130 ° C. and a wind speed setting scale of 50%, pressing is performed at 40 MPa-G, and the density of the mixture layer is 3 An electrode (positive electrode) of ³ g / cm ³ was obtained.

[Comparative Example 6]
Except having replaced the electroconductive bridge | crosslinking film (1) with the electroconductive film (c1), it carried out similarly to Example 13 and obtained the electrode (positive electrode) whose density of a mixture layer is 3.3 g / cm < ³ >. .

[Reference Example 2]
94 parts by weight of LiCoO ₂ (manufactured by Nippon Chemical Industry Co., Ltd .; “Cellseed C-10N”), Ketjen Black ECP (trade name) as carbon black (Ketjen Black International, Ketjen Black EC300J powder, 200 3 parts by weight of mesh / 75 μm pass 98% or more), 3 parts by weight of ethylene-acrylonitrile copolymer (ethylene unit 22 mol%, acrylonitrile unit 78 mol%) and NMP are mixed to prepare a solid content concentration of 67%. The mixture was kneaded for 5 minutes using a kneader (manufactured by Shinky Corp .; AR-250) to obtain a positive electrode mixture (D) for a non-aqueous electrolyte secondary battery.

The same procedure as in Example 13 was carried out except that the positive electrode mixture (C) for nonaqueous electrolyte secondary batteries was replaced with the positive electrode mixture (D) for nonaqueous electrolyte secondary batteries, and the density of the mixture layer was 3.4 g. An electrode (positive electrode) of / cm ³ was obtained.

  The peel strength between the electrode (negative electrode and positive electrode) current collector (conductive crosslinked films (1) and (2), conductive film (c1), copper foil, aluminum foil) and the mixture layer is defined in JIS K6854. The measurement was performed according to a 90 ° peel test.

  Table 2 shows the evaluation results of the current collector, the mixture, and the peel strength that form the electrodes obtained in Examples and Comparative Examples.

Claims (18)

Vinylidene fluoride polymer (a) 40 to 93 parts by weight,
5 to 25 parts by weight of conductive carbon black (b),
2 to 30 parts by weight of a crosslinking agent (c) and
Conductive crosslinked film formed by crosslinking a vinylidene fluoride resin composition containing 0 to 5 parts by weight of a lubricant (d) (where the total of (a) to (d) is 100 parts by weight) . The vinylidene fluoride resin composition is a vinylidene fluoride polymer (a) 40-92.9 parts by weight,
5 to 25 parts by weight of conductive carbon black (b),
2 to 30 parts by weight of a crosslinking agent (c) and
The conductive crosslinked film according to claim 1, comprising 0.1 to 5 parts by weight of the lubricant (d).   The conductive crosslinked film according to claim 1 or 2, wherein the vinylidene fluoride-based resin composition contains 0.1 to 5 parts by weight of fibrous carbon (e).   The conductive crosslinked film according to any one of claims 1 to 3, wherein the crosslinking is performed by irradiating the vinylidene fluoride resin composition with ionizing radiation.   The conductive crosslinked film according to claim 4, wherein the ionizing radiation is ultraviolet rays, electron beams, γ rays, or α rays.   The conductive cross-linked film according to any one of claims 1 to 5, wherein the vinylidene fluoride polymer (a) is a vinylidene fluoride polymer having 70 mol% or more of a structural unit derived from vinylidene fluoride. .   The electrically conductive crosslinked film according to any one of claims 1 to 6, wherein the lubricant (d) is a metal soap lubricant.   The conductive crosslinked film according to claim 7, wherein the metal soap-based lubricant is at least one metal soap-based lubricant selected from calcium stearate and magnesium stearate. The conductive crosslinked film according to any one of claims 1 to 8,
An electrode for a nonaqueous electrolyte secondary battery formed from a vinylidene fluoride polymer and a mixture for a nonaqueous electrolyte secondary battery containing an electrode active material. The conductive crosslinked film according to any one of claims 1 to 8,
A negative electrode for a non-aqueous electrolyte secondary battery formed from a negative electrode mixture for a non-aqueous electrolyte secondary battery containing a vinylidene fluoride polymer and a carbon-based negative electrode active material. The conductive crosslinked film according to any one of claims 1 to 8,
A positive electrode for a non-aqueous electrolyte secondary battery formed from a positive electrode mixture for a non-aqueous electrolyte secondary battery containing a vinylidene fluoride polymer and a lithium-based positive electrode active material. By co-extruding the vinylidene fluoride resin composition and the olefin resin, a multilayer film having a vinylidene fluoride resin composition layer and an olefin resin layer is formed,
Peeling off the olefin resin layer of the multilayer film to obtain a film comprising a vinylidene fluoride resin composition,
The conductive crosslinked film according to any one of claims 1 to 8, which is obtained by irradiating a film made of the vinylidene fluoride-based resin composition with ionizing radiation. 40-93 parts by weight of vinylidene fluoride polymer (a), 5-25 parts by weight of conductive carbon black (b), 2-30 parts by weight of crosslinking agent (c), and 0-5 parts by weight of lubricant (d) A vinylidene fluoride resin composition layer containing the vinylidene fluoride resin composition (provided that the total of (a) to (d) is 100 parts by weight) and an olefin resin are coextruded. A step (I) of forming a multilayer film having an olefin-based resin layer,
Step (II) of peeling off the olefin resin layer of the multilayer film to obtain a film comprising a vinylidene fluoride resin composition,
The manufacturing method of the electroconductive crosslinked film which has process (III) which irradiates an ionizing radiation to the film which consists of the said vinylidene fluoride resin composition.   The vinylidene fluoride resin composition comprises a vinylidene fluoride polymer (a) 40 to 92.9 parts by weight, conductive carbon black (b) 5 to 25 parts by weight, and a crosslinking agent (c) 2 to 30 parts by weight. And the manufacturing method of the electroconductive crosslinked film of Claim 13 containing 0.1-5 weight part of lubricants (d).   The method for producing a conductive crosslinked film according to claim 13 or 14, wherein the olefin resin has a melt flow rate (JIS K7210, 250 ° C, 2160 g load) of 1 g / 10 min or less.   A nonaqueous electrolyte secondary battery comprising the electrode for a nonaqueous electrolyte secondary battery according to claim 9.   The nonaqueous electrolyte secondary battery which has a negative electrode for nonaqueous electrolyte secondary batteries of Claim 10.   The nonaqueous electrolyte secondary battery which has a positive electrode for nonaqueous electrolyte secondary batteries of Claim 11.