JPH11228902A - Method for bonding vinylidene fluoride resin to metal substrate, electrode structure, and method for producing same - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a method for improving the metal adhesion of a polyvinylidene fluoride resin without impairing the inherent solvent resistance, mechanical and thermal properties of the polyvinylidene fluoride resin. Further, by using the method as a binder for a battery electrode structure, it is intended to improve the adhesiveness between the electrode active material layer and the current collector, and to obtain a non-aqueous battery with excellent performance. . When bonding a vinylidene fluoride resin to a metal substrate, (a) a vinylidene fluoride resin, and (b) an acrylic or methacrylic resin having a functional group exhibiting binding or affinity for a metal. Merging, (c) adding and mixing an organic compound having at least one functional group selected from a mercapto group, a thioether group, a carboxylic acid group, and a carboxylic anhydride group to a vinylidene fluoride resin; A method for bonding a vinylidene-based resin to a metal substrate, a battery electrode in which an electrode constituent material layer composed of at least an electrode active material and a binder is formed on the surface of a current collector, manufactured using the bonding method. Electrode and a non-aqueous battery using the electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding and laminating a vinylidene fluoride resin and an originally non-adhesive metal, and relates to a steel pipe lining requiring corrosion resistance, weather resistance or chemical resistance. , Chemical plant parts, batteries and other electrode binders.

[0002]

2. Description of the Related Art Polyvinylidene fluoride and vinylidene fluoride copolymer resins are paints, electric and electronic parts, steel pipe linings, and chemical plants that can be melt-molded with excellent weather resistance and chemical resistance. It is used for parts, weather-resistant antifouling films and the like. However, there is little adhesion to other materials, so that there is a disadvantage that it is difficult to combine or modify with other materials.

For this reason, various attempts have been made to introduce a carboxylic acid group into a polyvinylidene fluoride resin to impart hydrophilicity, improve adhesion, dispersibility of dyeability, and introduce a crosslinked site. For example, as a method for introducing a carboxylic acid group, a monomer having a carboxylic acid group or a group that can be converted to a carboxylic acid group such as acrylic acid or methacrylic acid ester or these esters is copolymerized with a vinylidene fluoride monomer and directly introduced. (Japanese Patent Laid-Open Publication No. 2-604 and others) are known.

However, when the above-mentioned method is employed in the production of a carboxylic acid group-containing polyvinylidene fluoride resin, the carboxylic acid group-containing monomer is complicated because of its copolymerization property with a fluorine-containing monomer. If a special product requiring a special manufacturing process is not used, the polymerization rate may be significantly reduced, or only a low molecular weight product may be obtained. There was a disadvantage such as there.

Further, Japanese Patent Laid-Open Publication No. Sho 50-41791.
Discloses a method of grafting a carboxylic acid group-containing fluorine monomer under ionizing radiation irradiation, but in this method, in addition to the industrial difficulty of handling radiation, the polymer main chain There was a problem that simultaneous decomposition or crosslinking reaction occurred. As described above, in all of the conventional examples that have been tried for the fluoropolymer, there have been difficulties in industrial practice.

On the other hand, in a lithium secondary battery which has recently been used for portable equipment such as a mobile phone, a video camera and a notebook personal computer, as a negative electrode active material, coke for doping and undoping lithium ions is used. Carbonaceous materials such as graphite and graphite are used (Publication Publication No. 62-90863). As the positive electrode active substance, transition metal oxides such as manganese oxide and vanadium pentoxide, and iron sulfide and titanium sulfide are used. Transition metal oxides, and composite compounds of these with lithium (eg, lithium cobalt composite oxide, lithium cobalt nickel composite oxide, lithium manganese oxide) and the like are used. In these cases, usually, a mixture of a powdery electrode active material and an appropriate amount of a binder added with an appropriate amount of a binder, mixed with a solvent to form a paste, applied to the current collector, dried and pressed to obtain an electrode.

The binder used for the electrode of such a secondary battery is required to have resistance to an organic solvent used for an electrolytic solution and resistance to active species generated by an electrode reaction. Solubility in certain solvents is also required. In many cases, a polyvinylidene fluoride (PVDF) resin is used as a binder satisfying these. However, PVDF resin originally has poor adhesion to metal, and in both cases of the negative electrode and the positive electrode, after the active material is pressed against the current collector, the adhesive force between the current collector and the active material is not sufficient. Further, there has been a problem that the active substance is easily peeled off from the current collector, and the cycle characteristics of the battery are deteriorated.

As a method for improving the adhesion between the current collector and the electrode active material, it has been proposed to roughen the surface of the current collector (JP-A-5-6766). The nature is not enough, and further improvement is required. Further, a copolymer of vinylidene fluoride and a monomer having a carboxylic acid group (JP-A-6-17245)
No. 2) has been proposed, but usually, copolymerization of a fluorine-based monomer with another monomer having a carboxylic acid group is not easy, and mass production is difficult and it cannot be said that it is practical. Furthermore, a method of adding a sulfur-containing organic compound having a mercapto group or the like to a paste-like electrode mixture (Japanese Patent Application Laid-Open No. 9-82311).
No. 9-82314), a method in which one or both of an acrylic resin having a functional group and a PVDF-based copolymer are mixed with a PVDF resin and used as a binder (Japanese Patent Application Laid-Open No. 9-199132, Same Hei 9-199134
No. 9-199130).
There is a demand for stronger adhesion than those obtained by these methods.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a metal bonding method in which a metal bonding property is introduced by a simple method without impairing the solvent resistance, mechanical and thermal properties inherent to the vinylidene fluoride resin. To provide an electrode structure having improved adhesiveness between an electrode active material and a current collector by using the composition as a binder for a battery electrode by providing a conductive vinylidene fluoride resin composition With the goal.

[0010]

Means for Solving the Problems The present inventors have developed a vinylidene fluoride resin, an acrylic or methacrylic polymer having a functional group having binding or affinity for a metal, and a mercapto group, A composition composed of three components of an organic compound having at least one functional group selected from a thioether group, a carboxylic acid group, and a carboxylic anhydride group and having a specific composition ratio exhibits adhesiveness to a metal material. That these properties are PVDF
It has been found that it is useful not only for producing a composite material composed of a base resin and a metal, but also as a binder used for stably fixing an electrode active substance to a current collector.

That is, according to the present invention, when a vinylidene fluoride resin is adhered to a metal substrate, the vinylidene fluoride resin has a (a) vinylidene fluoride resin and (b) a functional group exhibiting binding or affinity for the metal. At least one polymer selected from acrylic and methacrylic polymers or an acrylic or methacrylic resin composition containing them, and (c) a mercapto group, a thioether group, a carboxylic acid group, and a carboxylic anhydride group. The present invention relates to a method for bonding a vinylidene fluoride resin to a metal substrate, comprising adding and mixing an organic compound having at least one selected functional group to the vinylidene fluoride resin.

The vinylidene fluoride resin referred to herein is
Homopolymer of vinylidene fluoride (homopolymer) and copolymer of vinylidene fluoride with other monomer copolymerizable with vinylidene fluoride (vinylidene fluoride copolymer)
And may be used alone or as a mixture of two or more resins.

Such a vinylidene fluoride-based copolymer has a vinylidene fluoride component ratio of 50 to 50 in the copolymer.
98% by weight, more preferably 75 to 9%.
6% by weight. Here, as the other monomer copolymerizable with vinylidene fluoride, a fluorine-based monomer such as ethylene tetrafluoride, propylene hexafluoride, ethylene trifluoride, or ethylene trifluoride chloride is desirable.
More than one species can be used. In particular, when a mixture of a vinylidene fluoride homopolymer and a vinylidene fluoride-based copolymer is used, the vinylidene fluoride-based copolymer is 75 to 9%.
At a vinylidene fluoride component ratio of 6% by weight, room temperature (23
It is desirable that the material has a flexural modulus at 1000 ° C. or less and an elongation at break of 50% or more.

These vinylidene fluoride resins can be prepared by subjecting vinylidene fluoride monomers and other monomers to a known suspension polymerization method or emulsion polymerization method (reference example, “Fluorine Resin Handbook”, edited by Satokawa, 1990, Nikkan Kogyo Shimbun) )). As a method of copolymerizing a vinylidene fluoride monomer with another monomer, for example, US Pat. Nos. 4,076,929 and 4,569,978
And Japanese Patent Publication No. 6-336510. In this case, the monomer composition distribution of the obtained copolymer can be changed by controlling the method of adding the monomer, the chain transfer agent, and the polymerization initiator.
JP-A-6-336510 describes a method for obtaining a mixture of a vinylidene fluoride homopolymer and a copolymer in a polymerization step, and the polymer obtained by this method is a vinylidene fluoride-based polymer of the present invention. It is preferably used as a resin. In any of these vinylidene fluoride polymers used in the present invention, 230 ° C., 2.16
Melt flow rate (MFR) under kg load is 0.0
It is preferably from 03 to 300 g / 10 min, more preferably from 0.01 to 30 g / 10 min.

In the present invention, 1 to 99% by weight of vinylidene fluoride homopolymer and 99 to 1% by weight of vinylidene fluoride copolymer resin can be used as the component a. Depending on the mixing ratio, properties such as flexibility and solvent resistance of the resin change (that is, the flexibility is increased by increasing the proportion of the vinylidene fluoride-based copolymer, while the swelling due to the solvent is increased). The most suitable one is used according to the purpose.

The acrylic or methacrylic polymer having a functional group exhibiting binding or affinity for a metal used as the component b in the present invention is a polymer containing alkyl acrylate or alkyl methacrylate as a main component. At least one of the chain, side chain, and terminal has a functional group that exhibits binding or affinity for a metal. Examples of such polymers include radical polymerization, ionic polymerization, and coordination from at least one type of monomer selected from alkyl acrylates and alkyl methacrylates and a monomer having a functional group exhibiting binding or affinity for a metal. There are random copolymers, block copolymers, and graft polymers that are polymerized by a method such as polymerization.

The functional group contained in the component b having binding or affinity for metal includes a carboxylic acid group or a carboxylic anhydride group, an epoxy group (glycidyl group), a mercapto group, a sulfide group, an oxazoline group, and a phenol group. Group, ester group and the like.

As an example of the acrylic or methacrylic polymer, there is a copolymer of at least one monomer selected from those having a carboxylic acid group or a carboxylic anhydride group with an alkyl acrylate and / or an alkyl methacrylate. . In this case, examples of the alkyl acrylate and alkyl methacrylate include, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and the like. Further, monomers having a carboxylic acid group or a carboxylic acid anhydride group include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, alkenyl succinic acid, acrylamide glycolic acid, 1,2
-Unsaturated carboxylic acids such as allyl cyclohexanedicarboxylate, and unsaturated carboxylic anhydrides such as maleic anhydride and alkenyl succinic anhydride.

In such an acrylic or methacrylic polymer, at least 50% by weight of the polymer is preferably composed of at least one monomer selected from alkyl acrylates and alkyl methacrylates, and more preferably. Is 70 to 99% by weight. The amount of the functional group exhibiting binding or affinity for the metal contained is preferably 0.01 to 2 mol per 1 kg of the acrylic or methacrylic polymer. When the polymer component is a copolymer with at least one kind of monomer selected from alkyl acrylate and alkyl methacrylate and a monomer having a carboxylic acid group or a carboxylic acid anhydride group, the carboxylic acid group or the carboxylic acid anhydride group is used. The proportion of the monomer is preferably from 0.2 to 30% by weight of the copolymer, more preferably from 1 to 20% by weight. Also,
In addition to the above, a vinyl monomer such as styrene or a modified product such as imidization may be contained in the molecular chain as the constituent, but the content thereof is 50% by weight or less of the polymer. 30% by weight or less.

The component (b) used in the present invention is an acrylic or methacrylic polymer having no special functional group and an acrylic or methacrylic polymer having a functional group exhibiting binding or affinity for the above-mentioned metals. And a composition comprising:

The organic compound having at least one functional group selected from the group consisting of a mercapto group, a thioether group, a carboxylic acid group, and a carboxylic acid anhydride group used as the component c in the present invention has a polymer b component. Is a compound having a relatively low molecular weight. The molecular weight range is 5000 or less, preferably 2000 or less, and more preferably 60 to 1000.

Among these, the sulfur-containing organic compound having a mercapto group includes an organic compound having a plurality of (2 to 6) mercapto groups in one molecule, or at least one organic compound having a mercapto group.
Mercaptocarboxylic acids having at least one mercapto group and at least one carboxylic acid group, or at least one
Mercaptocarboxylic esters having one mercapto group and at least one ester group, or mercaptosulfides having at least one mercapto group and at least one thiol group are preferred.

Among them, the organic compounds having a plurality of mercapto groups in one molecule include ethanedithiol,
Examples include 1,3-propanedithiol, hexanedithiol, pentaerythrithiol, dimercaptodiethylether, 1,8-dimercapto-3,6-dioxaoctane, 1,5- or 2,7-dimercaptonaphthalene. Examples of mercaptocarboxylic acids include thioglycolic acid and 3-mercaptopropionic acid. Examples of mercaptocarboxylic acid esters include 2-ethylhexyl β-mercaptopropionate,
Derivatives of mercaptopropionic acid such as 3-methoxybutyl β-mercaptopropionate, trimethylolpropane tris (β-thiopropionate) and pentaerythritetra (mercaptopropionate), 2-ethylhexyl thioglycolate, thioglycol There are thioglycolic acid derivatives such as isooctyl acid, butyl thioglycolate, methoxybutyl thioglycolate, and trimethylolpropane tris (thioglycolate). Examples of mercaptosulfides include 2,2′-
There are dimercaptodiethylsulfide and bis- (2-mercaptoethyl) sulfide.

As the c component, 2-substituted-4,6-dimercapto-1,3,5-represented by the following structural formula 1
Triazine derivatives are also preferably used.

Embedded image [Where R is OR ₁ , SR ₂ , NR ₁ R ₂ (R ₁ and R ₂
Represents the same or different hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an arylalkyl group, or an alkylaryl group. ) And M represent hydrogen, an alkali metal or an alkaline earth metal. ] It is a compound represented by these.

Here, the alkyl group is methyl, ethyl, propyl, butyl, t-butyl, pentyl, hexyl, octyl, nonyl, 2-ethylhexyl, dodecyl or octadecyl group, and the alkenyl group is allyl or oleyl. Group as an arylalkyl group, benzyl, methylbenzyl, phenylethyl,
Alternatively, a phenylpropyl group, as an aryl group,
A phenyl or naphthyl group; and an alkylaryl group such as ethylphenyl, butylphenyl, octylphenyl, or 4′-hydroxy-3 ′, 5′-di-
Examples thereof include a t-butylphenyl group.

The organic compound having a thioether group used as the component c in the present invention may be, in addition to the thioether group, at least one functional group selected from a carboxylic acid group, a carboxylic anhydride group, an ester group and an amide group. It is desirable to have a group. Among these, examples of thioethers having a carboxylic acid group or a carboxylic anhydride group include 3,3′-thiodipropionic acid, carboxyethylthiosuccinic acid, carboxyethylthiosuccinic anhydride,
There is hydroxyethylthiopropionic acid. Examples of thioethers having an ester group include dilauryl thiodipropionate, distearyl thiodipropionate,
There are dioctadecyl thiodipropionate, ditetradecyl thiodipropionate, and didodecyl thiodipropionate. An example of a thioether having an amide group is hydroxyethylthiopropionamide.

In the present invention, the organic compound having a thioether group is preferably represented by the following formula:

Embedded image (However, R ₃ and R ₄ are a hydrocarbon group having 2 to 20 carbon atoms, m
And n are the same or different and are each an integer of 1 to 4), and thioether carboxylic acid or an anhydride thereof is preferably used, and carboxyethyl thiosuccinic acid and carboxyethyl thiosuccinic anhydride are more preferable.

The thioether having an amide group includes
Next formula

Embedded image (Where R ₅ and R ₆ are hydrocarbon groups having 2 to 20 carbon atoms), for example, hydroxyethylthiopropionamide.

Further, as the component c, an organic compound having at least one functional group selected from a carboxylic acid group and a carboxylic acid anhydride can be used. Examples of these include acetic acid, acrylic acid, formic acid, citric acid, oxalic acid, lactic acid, maleic acid, propionic acid, malonic acid, butyric acid and the like.

The vinylidene fluoride resin composition of the present invention having improved metal adhesion has the following properties: (a) 100 parts by weight of vinylidene fluoride resin; 0.5 to 50 parts by weight, more preferably 1 to 20 parts by weight, of an acrylic or methacrylic polymer having the functional group shown, and (c) a mercapto group, a thioether group, a carboxylic acid group, and a carboxylic anhydride group 0.01 to 5 parts by weight, more preferably 0.03 to 5 parts by weight of an organic compound having at least one functional group selected from
Contains 1 part by weight. If the amount of the component (b) or component (c) is too small, the effect of improving the adhesion between the metal and the vinylidene fluoride resin composition becomes insufficient. If the amount is too large, the mechanical properties of the vinylidene fluoride resin inherently exist. Properties, chemical resistance, solvent resistance, etc. are lost.

In the present invention, in particular, when the bonding process is a solution coating method, the vinylidene fluoride resin is 1 to 1
It contains 5% by weight of a vinylidene fluoride-based copolymer, and the amount of the component (b) acrylic or methacrylic-based polymer is 0.5 to 10 with respect to 100 parts by weight of the vinylidene fluoride-based resin.
It is desirable that the organic compound of the component c is added in an amount of 0.03 to 1 part by weight, more preferably 1 to 5 parts by weight.

The vinylidene fluoride resin composition having improved metal adhesion by the above-mentioned method can be used as an adhesive when the vinylidene fluoride resin is bonded to a metal. In this case, the vinylidene fluoride resin used for the adhesive does not necessarily need to be made of the same resin as the vinylidene fluoride resin to be the surface layer.

The metal adhesive composition of the present invention is produced by a solution process or a melting process. In the case of a solution process, the above three components a, b, and c are mixed at a predetermined ratio with N
-Methylpyrrolidone, N, N-dimethylformamide,
It may be dissolved at a temperature lower than the boiling point of the solvent used for a solvent such as tetrahydrofuran, dimethylacetamide, dimethylsulfoxide, hexamethylsulfonamide, tetramethylurea, acetone, and methylethylketone. In the case of the melting process, a, b, c
Can be produced by a conventional method in which the three components are heated and kneaded at a predetermined ratio. Here, a conventionally known method can be used as a method of melt-kneading, for example, using a Banbury mixer, a rubber roll machine, a single-screw or twin-screw extruder, and usually 100 to 300 ° C., preferably depending on the composition. Is melt-kneaded at a temperature of 150 to 260 ° C. to obtain a resin composition.

Examples of the metal material used as the substrate to be adhered in the present invention include iron, stainless steel, aluminum, copper,
Examples include nickel, titanium, lead, silver, chromium, and various alloys, and their shapes are not particularly limited.

[0035]

As described above, according to the present invention, the adhesion between a vinylidene fluoride resin and a metal material can be easily improved.
A composite material of a metal material and a vinylidene fluoride resin can be easily obtained. As the composite material obtained by this method, films, sheets, plates, pipes, rods, strands, monofilaments, fibers and various shapes are possible, and the production methods include calendaring, extrusion lamination, multilayer injection, Fluid dipping, dipping,
Spray painting, melt press, etc. Further, the method of the present invention can also be used for coating a wire with a fluorine-based paint or vinylidene fluoride-based resin using a vinylidene fluoride-based resin dissolved or dispersed in a solvent.

Further, the method for bonding a polyvinylidene fluoride resin to a metal substrate according to the present invention is directed to a method for bonding a battery in which an electrode constituting material layer comprising at least an electrode active material and a binder is formed on the surface of a current collector. It can be applied to the production of an electrode structure, thereby improving the adhesiveness between the electrode active material and the current collector and preventing the electrode active material from dropping off from the current collector during battery production. Instead, a battery electrode with improved cycle characteristics is finally obtained. In particular, it is useful as a binder for electrodes of non-aqueous secondary batteries, for example, lithium ion secondary batteries.

In this case, the current collector of the electrode may be a metal foil, a metal mesh, a three-dimensional porous body, or the like. As the metal used for the current collector, a metal which is difficult to alloy with lithium is desirable. , Iron, nickel, cobalt, copper, aluminum, titanium, vanadium, chromium, and manganese alone or alloys thereof.

As the negative electrode active material among the electrode active materials, any material capable of doping and undoping lithium ions may be used. Such materials include coke materials such as petroleum coke and carbon coke, carbon blacks such as acetylene black, graphite, glassy carbon, activated carbon, carbon fiber, and organic polymers fired in a non-oxidizing atmosphere. There is a carbonaceous material such as a fired organic polymer obtained. In some cases, copper oxide is added to these.

The positive electrode active substance is the one generally used as described above, and is not particularly limited. further,
A conductor may be added to this.

As an example of a process for producing an electrode, a predetermined amount of an electrode active substance, (a) the vinylidene fluoride resin described above as a binder, and (b) a functional group exhibiting binding or affinity for a metal The above-mentioned acrylic or methacrylic polymer having the following formula: and (c) the above-mentioned organic compound having at least one functional group selected from a mercapto group, a thioether group, a carboxylic acid group, and a carboxylic acid anhydride group in the presence of a solvent The slurry obtained by kneading under the following conditions is applied to an electrode current collector, dried, and then pressed as necessary to obtain an electrode. In this case, after the slurry is applied, if necessary, the temperature is 60 to 250 ° C, more preferably 80 to 250 ° C.
It is desirable to perform heat treatment at 200 ° C. for 1 minute to 10 hours. If necessary, a conductivity-imparting agent or other additives (such as copper oxide) may be added to the electrode constituent material layer.

Here, as a solvent used for obtaining a slurry to be coated on the electrode current collector, N-methylpyrrolidone, N, N-dimethylformamide, tetrahydrofuran, dimethylacetamide, dimethylsulfoxide,
Organic solvents such as hexamethylsulfformamide, tetramethylurea, acetone, and methyl ethyl ketone and water may be used, and these may be used alone or in combination.
Of these, N-methylpyrrolidone is particularly preferably used. Moreover, you may add a dispersing agent as needed.
In this case, a nonionic dispersant is preferably used.

Further, a binder (a) added to the electrode active material
The total amount of the component and the component b) is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, based on 100 parts by weight of the electrode active material. The optimal amount of this addition varies depending on the type of the battery or the electrode. The mutual ratios of the components a, b, and c are as described above.

The preferred vinylidene fluoride resin as the component a depends on the properties required for batteries and electrodes. The vinylidene fluoride homopolymer, the vinylidene fluoride copolymer described above, or the vinylidene fluoride homopolymer 1 ~ 99
% By weight and a mixture consisting of 99 to 1% by weight of vinylidene fluoride copolymer resin. For example, in the case of a thin battery or a prismatic battery that requires flexibility in the electrodes, a vinylidene fluoride copolymer such as a copolymer of vinylidene fluoride and propylene hexafluoride, or a vinylidene fluoride copolymer such as this is used. If a mixture of the coalesced and vinylidene fluoride homopolymer is preferably used, and flexibility is not needed,
A vinylidene fluoride homopolymer is preferably used. The method of the present invention is effective for enhancing the adhesion between the current collector and the electrode active layer, regardless of the type of vinylidene fluoride resin used. In particular, when the component a is a mixture of 80 to 99% by weight of a vinylidene fluoride homopolymer and 20 to 1% by weight of a vinylidene fluoride-based copolymer resin, the swelling property with respect to a carbonate-based solvent generally used for a lithium battery is as follows: Since it is comparable to that of vinylidene fluoride homopolymer and has improved flexibility as compared with vinylidene fluoride homopolymer, it is preferably used for liquid lithium batteries.

The negative electrode structure and the anode structure manufactured as described above are arranged with a liquid-permeable separator (for example, a porous film made of polyethylene or polypropylene) interposed therebetween. A non-aqueous secondary battery is formed by impregnation with an aqueous electrolyte. Further, there is provided a structure obtained by winding a laminate composed of a negative electrode structure having an active layer formed on both sides / a separator / a positive electrode structure having both sides an active layer / separator in a roll shape (a spiral shape). After being accommodated in a metal casing at the bottom, the negative electrode is connected to the negative electrode terminal, the positive electrode is connected to the positive electrode terminal, and impregnated with an electrolyte, the casing is sealed to obtain a cylindrical secondary battery.

As the electrolytic solution used here, for example, in the case of a lithium ion secondary battery, a solution obtained by dissolving a lithium salt as an electrolyte at a concentration of about 1 M in a non-aqueous organic solvent is used. Here, as a lithium salt, LiP
F ₆ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiSO
₃ CF ₃ and Li [(SO ₂ CF ₃ ) ₂ N]. As the non-aqueous organic solvent, for example, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and the like alone or in combination of two or more Used as a mixture.

Hereinafter, the present invention will be described with reference to Examples.
The present invention is not limited at all by the examples.

[0047]

【Example】

Example 1 900 g of N-methylpyrrolidone (NM
In P), elf., Which is a homopolymer of vinylidene fluoride,
Akin Chem 461 (230 ° C, 2.16k)
97 g of an MFR under a load of 0.03 g / 10 min, a flexural modulus at 23 ° C. of 1500 MPa), and polymethyl methacrylate having a carboxylic anhydride group introduced therein (SUMIPEX, manufactured by Sumitomo Chemical Industries, Ltd.) TR) is 3 g, and 2,
A solution (S-1) obtained by dissolving 0.3 g of 4,6-trimercapto-1,3,5-triazine was applied to an aluminum plate and a copper plate having a thickness of 1 mm and left at 120 ° C. for 1 hour. And dried under reduced pressure.

The obtained polymer-coated surface was cut at 1 mm intervals and subjected to a grid test (according to JIS K5400 6.15). As a result, the adhesion residual ratio of the polymer-coated layer was 100% for both aluminum and copper plates, and further, When a tape peeling test was performed, the residual adhesion rate was 85% on an aluminum plate and 100% on a copper plate. It was confirmed that the adhesion between the vinylidene fluoride resin composition and the metal plate was good. Further, the solvent swelling degree of the polymer layer after immersion in ethylene carbonate at 60 ° C. for 72 hours was 24%, which was almost the same as the value for the vinylidene fluoride homopolymer.

[0049]

Example 2 In Example 1, as a vinylidene fluoride resin, a Kynar 2801 (propylene hexafluoride manufactured by Elf Atochem Co.), which is a copolymer of vinylidene fluoride and propylene hexafluoride, was used instead of the Kynar 461. MF at a content of 10% by weight, 230 ° C. and 2.16 kg load
R is 0.2 g / 10 min, flexural modulus at 23 ° C. is 600
An NMP solution (S-2) was prepared in the same manner as in Example 1 except that MPa) was used. As a result of the same cross-cut test, the adhesion residual ratio of the polymer coating layer was 100% for both the aluminum and copper plates. Further, in the tape peeling test, the adhesion residual ratio was 90% on the aluminum plate and 100% on the copper plate. .

[0050]

Example 3 In 900 g of NMP, Kynar 30 manufactured by Elf Atochem, a vinylidene fluoride homopolymer, was used.
1F (MFR at 230 ° C. under a load of 2.16 kg is 0.
(03 g / 10 min), 87 g of the copolymer Kiner 28 of vinylidene fluoride and propylene hexafluoride described in Example 2.
01 and 10 g of Sumipex TR described in Example 1
g, and 2,4,6-trimercapto-1,3,5-
A solution (S-3) obtained by dissolving 0.1 g of triazine was
Apply to 1mm thick aluminum plate and copper plate, 12
After leaving at 0 ° C. for 1 hour, drying under reduced pressure was performed.

The obtained polymer-coated surface was cut at 1 mm intervals and subjected to a grid test (according to JIS K5400 6.15). As a result, the adhesion residual ratio of the polymer-coated layer was 100% for both aluminum and copper plates. When a tape peeling test was performed, the adhesion residual ratio was 100% on both the aluminum plate and the copper plate.
It was confirmed that the adhesion between the vinylidene fluoride resin composition and the metal plate was good. Further, the solvent swelling degree of the polymer layer after immersion in ethylene carbonate at 60 ° C. for 72 hours was 26%, which was slightly increased as compared with pure Kainer 301F, but no significant change was observed.

[0052]

Example 4 In 900 g of NMP, Kynar 301F was added.
48 g, 48 g of a copolymer kainer 2801 of vinylidene fluoride and propylene hexafluoride described in Example 2, 4 g of Sumipex TR described in Example 1, and 2,4,
6-trimercapto-1,3,5-triazine is added to 0.6
g was dissolved to prepare a solution (S-4). As a result of a grid test performed in the same manner as in Example 3, the adhesion residual ratio of the polymer coating layer was 100% for both the aluminum and copper plates, and also in the tape peeling test, the adhesion residual ratio was 100% for both the aluminum plate and the copper plate. Met.

[0053]

Example 5 An NMP solution (S-5) was prepared in the same manner as in Example 3 except that 2,4,6-trimercapto-1,3,5-triazine was replaced with 3-mercaptopropionic acid. ) Was prepared. As a result of the same cross-cut test, the adhesion residual ratio of the polymer coating layer was 100% for both the aluminum and copper plates. Further, in the tape peeling test, the adhesion residual ratio was 95% on the aluminum plate and 100% on the copper plate. .

[0054]

Example 6 The procedure of Example 3 was repeated except that 2,4,6-trimercapto-1,3,5-triazine was replaced with carboxyethylthiosuccinic anhydride.
A P solution (S-6) was prepared. As a result of the same cross-cut test, the residual adhesion ratio of the polymer coating layer was 100% for both the aluminum and copper plates, and the adhesive peel ratio was 100% for both the aluminum and copper plates in the tape peeling test.

[0055]

Example 7 In Example 3, maleic anhydride, N-methyldimethylglutarimide, a carboxylic acid-containing monomer, and methacrylic acid were used as acrylic polymers having a functional group exhibiting binding or affinity for a metal. Copolymer of methyl (manufactured by Rohm and Haas Co., Ltd.
PARLOID EXL4151), except that an NMP solution (S-7) was prepared in the same manner as in Example 3. As a result of the similar cross-cut test, the residual adhesion rate of the polymer coating layer was
Both the aluminum and copper plates had 100% adhesion, and the tape peeling test also showed 100% adhesion retention for both aluminum and copper plates.

[0056]

Example 8 In Example 3, an epoxy-modified polymethyl methacrylate grafted with an epoxy-modified polymethyl methacrylate (Toa Gosei Chemical Industry Co., Ltd.) Example 3 except that Reseda GP-301) was used.
An NMP solution (S-8) was prepared in the same manner as described above. As a result of the same cross-cut test, the residual adhesion ratio of the polymer coating layer was 100% for both the aluminum and copper plates, and the adhesive peel ratio was 100% for both the aluminum and copper plates in the tape peeling test.

[0057]

Example 9 100 g of coal pitch coke pulverized by a ball mill as a negative electrode active material carrier was dispersed in 100 g of the NMP solution (S-1) obtained in Example 1 to form a slurry (paste). This slurry was applied to one side of a copper foil having a thickness of 20 μm as a current collector,
After drying at 15 ° C. for 15 minutes, an electrode structure (used as a negative electrode) having a thickness of 110 μm and a width of 20 mm was produced.

An adhesive tape was adhered to the electrode active layer on the electrode surface, and the adhesion strength between the current collector and the electrode active layer was measured by a tensile tester to be 185 g / cm. Also, after peeling, considerable residue of the electrode active substance was observed on the current collector, and it was confirmed that the adhesion between the electrode active substance and the current collector was very good. Further, in an adhesion test performed by winding the electrode into a roll having a diameter of 1 mm, no peeling of the electrode active layer was observed, and thereafter, the electrode was immersed in ethylene carbonate at 60 ° C.
After 3 days, no peeling of the electrode active layer was observed.

[0059]

Example 10 An electrode structure was produced in the same manner as in Example 9, except that S-2 obtained in Example 2 was used for the NMP solution. The adhesive strength between the current collector and the electrode active layer was 190 g / cm, and good adhesion was confirmed in other tests.

[0060]

Example 11 An electrode structure was produced in the same manner as in Example 9, except that S-3 obtained in Example 3 was used for the NMP solution. The adhesive strength between the current collector and the electrode active layer was 300 g / cm, and good adhesion was confirmed in other tests.

[0061]

Embodiment 12 LiCoO ₂ as a positive electrode active material was 9
4 g, 6 g of graphite as a conductive agent, and 1 NMP solution (S-3) obtained in Example 3 as a binder.
00g was mixed to form a slurry (paste). This slurry was applied to one side of a 20 μm-thick aluminum foil as a current collector, dried at 130 ° C. for 15 minutes,
An electrode structure (used as a positive electrode) having a thickness of 0 μm and a width of 20 mm was produced. The adhesive strength between the current collector and the electrode active layer is 2
It was 30 g / cm, and good adhesion was confirmed in other tests.

[0062]

Comparative Example 1 A solution (S-9) obtained by dissolving 100 g of polyvinylidene fluoride (Kyner 301F) in 900 g of NMP was applied to an aluminum plate and a copper plate having a thickness of 1 mm, and left at 120 ° C. for 1 hour. Further, drying under reduced pressure was performed. As a test for adhesion to the polymer coating layer, a grid test was performed in the same manner as in Example 1. As a result, the adhesion residual ratio of the polymer coating layer was 20% or less for both aluminum and copper plates. Further, when a tape peeling test was performed, all the polymer layers were peeled off. The degree of swelling in ethylene carbonate measured by the same method as in Example 1 using the polymer peeled from the metal plate was 23%.

[0063]

Comparative Example 2 A solution (S-10) obtained by dissolving 97 g of polyvinylidene fluoride (Kainer 461) and 3 g of Sumipex TR described in Example 1 in 900 g of NMP was applied to an aluminum plate and a copper plate having a thickness of 1 mm. Then 12
It was left at 0 ° C. for 1 hour and further dried under reduced pressure. As a test for adhesion to the polymer coating layer, a grid test was performed in the same manner as in Example 1. The adhesion residual ratio of the polymer coating layer was 100% for both aluminum and copper plates. The residual adhesion rate was about 50% on the plate and about 80% on the copper plate. .
The degree of swelling of the polymer layer with ethylene carbonate measured by the same method as in Example 1 was 24%.

[0064]

[Comparative Example 3] One Kynar 461 was added to 900 g of NMP.
00g and 2,4,6-trimercapto-1,3,5
-Solution comprising 0.3 g of triazine dissolved (S-11)
Is applied to a 1 mm thick aluminum plate and a copper plate,
It was left at 20 ° C. for 1 hour and further dried under reduced pressure. Example 1 shows an adhesion test for the polymer coating layer in Example 1.
When the cross-cut test was performed in the same manner as in the above, the adhesion residual ratio of the polymer coating layer was approximately 70% on the aluminum plate and approximately 90% on the copper plate. About 30% on copper, about 5 on copper plate
The residual adhesion rate was 0%. The degree of swelling of the polymer layer with ethylene carbonate measured by the same method as in Example 1 was 23%.

[0065]

Comparative Example 4 A copolymer of vinylidene fluoride and propylene hexafluoride in 900 g of NMP (Kyner 2801)
And a solution (S-12) obtained by dissolving 3 g of SUMIPEX TR were applied to an aluminum plate and a copper plate having a thickness of 1 mm, left at 120 ° C. for 1 hour, and further dried under reduced pressure. As a test for adhesion to the polymer coating layer, a grid test was performed in the same manner as in Example 1. The adhesion residual ratio of the polymer coating layer was 100% for both aluminum and copper plates. The adhesion residual rate was about 70% on the plate and about 90% on the copper plate. . The degree of swelling of the polymer layer with ethylene carbonate measured by the same method as in Example 1 was 42.
%Met.

[0066]

Comparative Example 5 A solution (S-13) obtained by dissolving 87 g of Kynar 301F, 10 g of Kynar 2801 and 3 g of Sumipex TR in 900 g of NMP was 1 m thick.
m on an aluminum plate and a copper plate.
It was left for a while and dried under reduced pressure. As a test for adhesion to the polymer coating layer, a grid test was performed in the same manner as in Example 1. As a result, the adhesion residual ratio of the polymer coating layer was 100% for both aluminum and copper plates.
In the tape peeling test, about 80% on aluminum plate,
The adhesion residual ratio was about 100% on the copper plate. The degree of swelling of the polymer layer with ethylene carbonate measured by the same method as in Example 1 was 26%.

[0067]

Comparative Example 6 In Example 9, the comparative example 1 was added to the NMP solution.
An electrode structure was produced in the same manner as in Example 9, except that S-9 obtained in was used. The adhesive strength between the current collector and the electrode active layer was a low value of 35 g / cm. Further, in the roll winding test using a cylinder having a diameter of 1 mm, peeling of the electrode active layer was recognized, and in the immersion test at 60 ° C. in ethylene carbonate, considerable peeling of the electrode active layer occurred.

[0068]

Comparative Example 7 In Example 9, the NMP solution was added to Comparative Example 2
An electrode structure was produced in the same manner as in Example 9, except that S-10 obtained in was used. The adhesive strength between the current collector and the electrode active layer was not so high as 70 g / cm. Further, in the roll winding test using a cylinder having a diameter of 1 mm, peeling of the electrode active layer was recognized, and in the immersion test at 60 ° C. in ethylene carbonate, considerable peeling of the electrode active layer occurred.

[0069]

Comparative Example 8 In Example 9, the comparative example 3 was added to the NMP solution.
An electrode structure was produced in the same manner as in Example 9, except that S-11 obtained in was used. The adhesive strength between the current collector and the electrode active layer was 76 g / cm, which was not so high. Further, in the roll winding test using a cylinder having a diameter of 1 mm, peeling of the electrode active layer was observed, albeit slightly, and in the immersion test in ethylene carbonate at 60 ° C., a part of the electrode active layer was peeled. .

[0070]

Comparative Example 9 In Example 9, the NMP solution was added to Comparative Example 4
An electrode structure was prepared in the same manner as in Example 9, except that S-12 obtained in was used. The adhesive strength between the current collector and the electrode active layer was 80 g / cm, which was not so high. Further, in the roll winding test using a cylinder having a diameter of 1 mm, peeling of the electrode active layer was observed, albeit slightly, and in the immersion test in ethylene carbonate at 60 ° C., a part of the electrode active layer was peeled. .

[0071]

Comparative Example 10 An electrode structure was produced in the same manner as in Example 9, except that S-13 obtained in Comparative Example 5 was used as the NMP solution. Although the adhesive strength between the current collector and the electrode active layer was as high as 210 g / cm, it was lower than the result in Example 11 using the solution S-3.
Further, in the roll winding test using a cylinder having a diameter of 1 mm and the immersion test in ethylene carbonate at 60 ° C., almost no peeling of the electrode active layer was observed. Sex was inadequate.

[0072]

According to the present invention, a metal-adhesive vinylidene fluoride resin composition can be obtained by a simple method without impairing the solvent resistance, mechanical and thermal properties inherent to the vinylidene fluoride resin. It becomes possible. When the metal-adhesive vinylidene fluoride resin composition of the present invention is used as a binder for an electrode of a battery, an electrode structure having a high adhesive strength between an electrode active substance and a current collector can be produced. As a result, not only can the separation of the electrode active material and the current collector during the production of the battery be prevented, but also a secondary battery can be obtained in which the discharge capacity is not deteriorated by repeated charge and discharge. The method of the present invention is particularly useful for non-aqueous secondary batteries such as lithium ion secondary batteries.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01M 4/02 H01M 4/02 B 4/04 4/04 A 4/62 4/62 Z // (C08L 27/16 33: 06)

Claims (23)

[Claims] When a vinylidene fluoride resin is adhered to a metal substrate, (b) a functional group exhibiting a binding property or an affinity for a metal with respect to 100 parts by weight of the vinylidene fluoride resin. At least one polymer selected from acrylic and methacrylic polymers having the following or an acrylic or methacrylic resin composition containing them at 0.5 to 50 parts by weight, (c) mercapto group, thioether group, carboxylic acid Group, and 0.01 to 5 parts by weight of an organic compound having at least one functional group selected from carboxylic anhydride groups to the vinylidene fluoride resin.
A method for bonding a vinylidene fluoride resin to a metal substrate, comprising mixing. 2. The method for bonding vinylidene fluoride resin to a metal substrate according to claim 1, wherein the vinylidene fluoride resin is a homopolymer of vinylidene fluoride. 3. A copolymer of a vinylidene fluoride resin and at least one monomer selected from ethylene tetrafluoride, propylene hexafluoride, ethylene trifluoride, and ethylene trifluoride chloride. Wherein the ratio of the vinylidene fluoride component in the copolymer is 50 to 98.
2. The method for bonding a vinylidene fluoride resin to a metal substrate according to claim 1, wherein the amount of the vinylidene fluoride resin is in the range of 1 wt%. 4. The vinylidene fluoride resin is a mixture of 1 to 99% by weight of vinylidene fluoride homopolymer and 99 to 1% by weight of a vinylidene fluoride copolymer resin according to claim 3. For bonding vinylidene fluoride resin to a metal substrate. 5. The method for bonding a vinylidene fluoride resin to a metal substrate according to claim 4, wherein the vinylidene fluoride copolymer resin has a flexural modulus at room temperature of 1000 MPa or less. 6. The metal substrate of the vinylidene fluoride resin according to claim 1, wherein the component b has at least one functional group selected from a carboxylic acid group and a carboxylic acid anhydride group. How to adhere to. 7. The metal substrate of the vinylidene fluoride resin according to claim 1, wherein the organic compound used as the component c is an organic compound having a plurality of mercapto groups in one molecule. Bonding method. 8. The organic compound having at least one thioether group and at least one functional group selected from a carboxylic acid group, a carboxylic anhydride, an ester group and an amide group as the component c. 7. The method for bonding the vinylidene fluoride resin according to any one of 6 to a metal substrate. 9. The organic compound used as the component c is represented by the following formula: [Where R is OR ₁ , SR ₁ , or NR ₁ R ₂ (R ₁ and R ₂ are the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an arylalkyl group, or Represents an alkylaryl group), and M represents hydrogen, an alkali metal or an alkaline earth metal. The vinylidene fluoride according to any one of claims 1 to 6, wherein a 2-substituted-4,6-dimercapto-1,3,5-triazine derivative represented by the following formula: is added and mixed. Method of bonding resin to metal substrate. 10. The organic compound used as the component c is represented by the following formula: (However, R ₃ and R ₄ are a hydrocarbon group having 2 to 20 carbon atoms, m
And n are the same or different and each is an integer of 1 to 4), which is a thioether carboxylic acid or an anhydride thereof, the vinylidene fluoride resin according to any one of claims 1 to 6, Bonding method. 11. An acrylic or methacrylic resin having, on at least one surface of a current collector, a functional group having a binding property or an affinity for a metal with respect to (b) 100 parts by weight of a vinylidene fluoride resin. 0.5 to 50 parts by weight of at least one polymer selected from the group-based polymers or an acrylic or methacrylic resin composition containing them, and (c) a mercapto group, a thioether group, a carboxylic acid group, and a carboxylic acid anhydride Applying a slurry obtained by mixing a solution obtained by dissolving 0.01 to 5 parts by weight of an organic compound having at least one functional group selected from a substance group in an organic solvent with an electrode active substance, and volatilizing the organic solvent. A method for producing an electrode structure, comprising: 12. The method for producing an electrode structure according to claim 11, wherein the vinylidene fluoride resin is a vinylidene fluoride homopolymer. 13. A copolymer of vinylidene fluoride and at least one monomer selected from the group consisting of ethylene tetrafluoride, propylene hexafluoride, ethylene trifluoride, and ethylene trifluoride chloride. And
When the ratio of the vinylidene fluoride component in the copolymer is 50 to 9
The method for producing an electrode structure according to claim 11, wherein the content is 8% by weight. 14. The vinylidene fluoride resin is a mixture of 1 to 99% by weight of vinylidene fluoride homopolymer and 99 to 1% by weight of the vinylidene fluoride copolymer resin according to claim 13. The method for producing the electrode structure of the above. 15. The vinylidene fluoride copolymer resin has a flexural modulus at room temperature of 1000 MPa or less.
5. The method for producing the electrode structure according to 4. 16. The method for manufacturing an electrode structure according to claim 11, wherein the component b has at least one functional group selected from a carboxylic acid group and a carboxylic acid anhydride group. 17. The method for producing an electrode structure according to claim 11, wherein the organic compound used as the component c is an organic compound having a plurality of mercapto groups in one molecule. 18. The organic compound having at least one thioether group and at least one functional group selected from a carboxylic acid group, a carboxylic anhydride, an ester group and an amide group as the component c. 17. The method for producing an electrode structure according to any one of items 16. 19. The organic compound used as the component c is a 2-substituted-4,6-dimercapto-1,3,5-triazine derivative represented by the structural formula 1 according to claim 9. The method for producing an electrode structure according to any one of the above. 20. The electrode structure according to claim 11, wherein the organic compound used as the component c is a thioethercarboxylic acid represented by the structural formula 2 according to claim 10 or an anhydride thereof. Method of manufacturing. 21. The production of an electrode structure according to any one of claims 11 to 20, wherein the total of the component a and the component b used in 100 parts by weight of the electrode active substance is 1 to 50 parts by weight. Method. 22. An electrode structure produced by the method according to claim 11. 23. A non-aqueous battery comprising a positive electrode, a negative electrode, and a separator layer disposed between the two electrodes, wherein at least one of the positive electrode and the negative electrode comprises the electrode structure according to claim 22.