CN1213393A - Method for bonding fluororesin and metal - Google Patents

Abstract

The object of the present invention is to provide a method for improving the adhesion between fluorinated resin and metal material and for obtaining a composite material of metal material and polyvinylidene fluoride resin. Fluorinated compositions having adhesion to metals can be used as adhesives between fluorinated resins and metals or can be used in place of fluorinated resins.

Description

Method for bonding fluororesin and metal

The present invention relates to a method for bonding/laminating fluororesins and metals that are not bonded per se. The present invention can be used for steel pipe linings, chemical plant parts and as Binders for battery electrodes, etc.

As a fluoropolymer that can be melted and molded and has excellent weather resistance, chemical stability, etc., polyvinylidene fluoride (hereinafter abbreviated as PVDF) resin can be used as a coating material and as an electric/electronic part, Steel pipe linings, chemical plant components and weather/stress resistant membranes to name a few. However, since it has practically no adhesion with other materials, it has the problem of being difficult to modify or compound with other materials.

Therefore, people try to mix other polymers with PVDF to overcome this shortcoming, but almost no polymer has adhesion or compatibility with PVDF, and its application range is extremely limited due to adverse effects on the physical properties of PVDF, etc. . For example, it is known that polymethyl methacrylate (hereinafter abbreviated as PMMA) is a material with good compatibility with PVDF (JP43-12012 and JP51-18197), but the glass transition temperature of PPMA is different from that of PVDF. The ratio is very high, so mixtures of these materials lack flexibility and they have poor adhesion to metals. On the other hand, people have also proposed a compound with polycarbonate (JP57-8244), a compound with a modified polyolefin with functional groups (JP62-57448) and a compound with polyimide (JP2- 308856), etc., but these compositions lack compatibility and they adhere poorly to metals. In addition, composites with acrylate or methacrylate elastomers have been proposed (JP4-218552), but their bonding properties to metal systems are not known.

The object of the present invention is to improve the adhesion between fluororesin and metal material, and to provide a method for obtaining a composite material of metal material and fluororesin.

The present inventors have discovered a fluorinated composition comprising at least two of the following three components:

(a) at least one PVDF resin,

(b) at least one acrylic and/or methacrylic polymer with functional groups having adhesion or affinity for metals,

(c) at least one vinylidene fluoride copolymer resin

The compositions have good adhesion to metallic materials and it has been found that these properties are effective in the preparation of composite materials consisting of these compositions and metals.

The PVDF resin mentioned herein may be selected from polyvinylidene fluoride homopolymers, and preferably its melt flow rate (MFR) at 230° C. under a load of 2.16 kg is 0.01-300 g/10 min.

Vinylidene fluoride copolymer (c) is a copolymer of vinylidene fluoride (VF ₂ ) and other monomers that can be copolymerized with VF ₂ , and the percentage of VF ₂ component in these copolymers should be 50-95% by weight , more preferably 75-95% by weight. As other copolymerizable monomers, preferably fluorine-containing monomers, such as tetrafluoroethylene, hexafluoroacrylic, trifluoroethylene, and chlorotrifluoroethylene, etc., one or more of them can be used. Suitably copolymers (c) have a flexural modulus at room temperature of not more than 1000 MPa and they have an elongation at break of at least 50%, preferably a melt flow rate (MFR) of 0.01 at 230°C under a load of 2.16 kg -300 g/10 min.

The fluororesins (a) and (c) can be obtained by polymerizing a vinylidene fluoride monomer or a vinylidene fluoride monomer and other monomers by a suspension polymerization method, an emulsion polymerization method, or the like.

The acrylic and/or methacrylic polymer (b) is one in which the main component is alkyl acrylate and/or alkyl methacrylate and it has an adhesive bond with metal in the main chain, side chain or terminal. Polymers with contact or affinity functional groups. As an example of such a polymer, it may be obtained by adding at least one monomer selected from alkyl acrylate and alkyl methacrylate by free radical polymerization, ionic polymerization or coordination polymerization. Random copolymers, block copolymers and graft polymers produced by monomers with adhesive or affinity functional groups.

As examples of functional groups having adhesion or affinity with metals, carboxylic acid groups or carboxylic acid anhydride groups, epoxy groups (glycidyl groups), mercapto groups, sulfur groups, oxazoline groups, phenol groups can be mentioned , ester groups and similar groups.

An example of the aforementioned acrylic and/or methacrylic polymer includes a copolymer of a monomer having a carboxylic acid group or a carboxylic anhydride group and an alkyl acrylate and/or an alkyl methacrylate. Specific examples of the alkyl (meth)acrylate in this case are methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate. In addition, as specific examples of monomers having carboxylic acid groups or carboxylic anhydride groups, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, alkenyl succinic acid, acrylic amido- Glycolic acid, allyl 1,2-cyclohexanedicarboxylate, and other similar unsaturated carboxylic acids, and maleic anhydride, alkenyl succinic anhydride, and other similar unsaturated carboxylic anhydrides, and the like.

In addition, preferably at least 50% by weight, more preferably at least 70% by weight of such acrylic and/or methacrylic polymers consist of at least one monomer selected from acrylates and/or methacrylates . The content of the functional group having adhesiveness or affinity with metal is preferably 0.01-2 mol per kg of acrylic and/or methacrylic polymer. When the polymer component is a copolymer of at least one monomer selected from acrylate and/methacrylate and monomers with carboxylic acid groups or carboxylic anhydride groups, with carboxylic acid groups or carboxylic anhydride groups The proportion of monomers of the cluster is preferably 0.2-30% by weight of the copolymer, more preferably 1-20% by weight. In addition, as a constituent, vinyl monomers such as styrene or modified units such as imide may be contained in the molecular chain in addition to the above-mentioned constituents, but the content of these constituents does not exceed 50% by weight of said polymer. %, and preferably no more than 30% by weight.

When the metal bonding composition contains components (a), (b) and (c), per 100 parts by weight of polyvinylidene fluoride resin (a), it contains 0.5-100 parts by weight of acrylic and/methyl Acrylic polymer (b), 1-200 parts by weight of vinylidene fluoride copolymer resin (c).

The metal-bonding composition of the present invention can be prepared by a solution method or a fusion method. In the case of the solution method, the above components (a) (b) and (c) can be dissolved in a solvent such as N-methylpyrrolidone, N,N-dimethyl formamide, tetrahydrofuran, dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylurea, acetone, methyl ethyl ketone or the like. In the case of the melting method, it can be produced by a conventional method such as heating and mixing components (a), (b) and (c) in a certain ratio using a screw mixer. Here, conventionally known methods can be used as the method of melting and mixing, such as using a Banbury mixer, a rubber roller, and a single or double screw extruder, etc., and usually by heating at 100-300 ° C, preferably at 150- The resin composition was obtained by melting and mixing at 260° C. (although it also depends on the composition).

In the present invention, if the vinylidene fluoride copolymer is added in an amount of 1-10 parts by weight, preferably 1-5 parts by weight, per 100 parts by weight of vinylidene fluoride resin, and similarly, if acrylic or methyl The amount of the acrylic polymer is 0.5-10 parts by weight, preferably 1-5 parts by weight, so that the adhesion to metal can be improved without greatly changing the properties of the vinylidene fluoride resin. This method is especially effective when the bonding process is a solution coating method.

In addition, the fluorinated composition of the present invention, the metal adhesive properties of which are improved by the above method, can be used as an adhesive when bonding a fluorinated resin to a metal. Especially when the bonding process is a melting process, preferably the three-component composition is composed of 5-100 parts by weight per 100 parts by weight of PVDF resin (a) acrylic or Composed of methacrylic polymer (b) and 10-200 parts by weight of vinylidene fluoride polymer (c).

In the present invention, the fluorinated composition having improved metal adhesion can be used as an adhesive when bonding a fluorinated resin to metal, said fluorinated resin not necessarily having a surface layer composed of The composition of the fluorinated resin is the same as that of the fluorinated resin. As the fluorinated resin used in the adhesive layer, a resin having an appropriate melt flow rate (MFR), copolymer composition and melting point can be selected according to the bonding/processing operation.

Examples of metal materials used as the bonding base material in the present invention are iron, stainless steel, aluminum, copper, nickel, titanium, lead, silver, chromium, and various alloys, etc., and the shape thereof is not particularly limited.

As mentioned above, through the present invention, the bonding of fluorinated resin (and materials containing fluorinated resin) to metal materials can be easily improved, and a fluorinated composite material bonded to metal can be easily obtained. Metal-bonded fluorinated composites obtained by this method consist of fluorinated resins, such as extruded articles (films, sheets, plates, tubes, rods, profiled extrusions, filaments, monofilaments, fibers, etc.) , injection-molded products or press-molded products, etc., part or the entire surface of which has a layer of the above-mentioned metal-bonded composition, and it is not particularly limited, and its preparation methods include calendering, co-extrusion, extrusion lamination, multi-layer Injection molding, fluid immersion coating, dipping, spraying and coating the surface of molded objects, etc. Here, the polyvinylidene fluoride resin used as the base material and the polyvinylidene fluoride resin used in the composition for bonding to metal may be the same or different.

The method of the present invention can be used for coating a fluorine material by using a fluorinated resin dissolved or dispersed in a solvent, or for wire coating by a fluorinated resin. In addition, it can also be used as an adhesive for lithium battery electrodes, etc., and in this case, it can be used to improve the contact between the metal substrate (current catcher for the battery) and the electrode active material layer. Adhesive properties.

The method of the present invention for bonding fluorinated resins, particularly PVDF resins and/or VF2 copolymer resins, to metals can be used in various products, and it is valuable in various fields, such as in chemical industry, In the medical and food industries, it can be used as a structural component in equipment that requires chemical inertness, as well as in external building materials and industrial materials that require long-term weather resistance, and can also be used as an adhesive for lithium battery electrodes, etc.

For the electrode production process of lithium-ion batteries, it can be used to enhance the bonding between the metal substrate of the current harvester and the electrode active material layer.

High capacity and long life in portable electronic products (cellular phones, pagers, personal digital assistants, devices for personal communication services, hand-held or hand-held box terminal computers, electronic games, log recorders, etc.) and electric vehicles Small rechargeable batteries are in high demand. Lithium-ion batteries (LIBs) are an attractive option because they are thin and lightweight, do not contain heavy metals that pose environmental concerns, and they have higher energy densities than existing nickel-cadmium, nickel-metal hydride, and lead-acid batteries. An excellent solution.

The laminate structure of lithium-ion batteries is generally described as follows:

-Metal catcher

- Lithium-metal oxide based positive electrode or cathode

- Electrolyte

- Carbon based negative electrode or anode

-Metal catcher

The anode active material can be made of any material that can be doped and release lithium ions, and the material is usually made of carbonaceous materials, including coke, such as petroleum coke and carbon coke. Carbon black, such as acetylene black, graphite, fiber carbon, activated carbon, carbon fiber, and sintered products made from organic high molecular polymers by burning organic high molecular polymers in a non-oxidizing atmosphere. Copper oxide or other conductive materials may be doped or added to the cathode active material.

Adhesives that must have high resistance to solvents and chemical agents are usually based on fluororesins, polyolefins, synthetic rubbers, however, fluorinated resins are preferred. The content of the fluorinated resin in the adhesive is preferably 90% by weight or more.

Preference is given to using PVDF resins, especially those with more than 75% by weight of VF2, because of their high resistance to solvents and to active agents, and thus their high solubility in methylpyrrolidone, methylpyrrolidone It is a commonly used solvent in lithium-ion batteries. In the PVDF resin, in the fluorinated copolymer consisting of a mixture of vinylidene fluoride homopolymer and fluorinated copolymer, the content of VF2 is 50-95% by weight, and the content of vinylidene fluoride homopolymer in the mixture is 50-99.5% by weight of those resins are preferred.

A conventional method for preparing an anode includes mixing a powdered carbonaceous material with an appropriate amount of a binder and kneading with a solvent to prepare a slurry or slurry. A trap (usually copper) is then coated onto the slurry which is then dried and compacted to obtain the anode.

Lithium-ion battery cathodes are usually made of lithium and transition metal oxides such as manganese oxide and vanadium oxide, transition metal sulfides such as iron sulfide and titanium sulfide, or composite compounds of these substances such as lithium and cobalt composite oxides, lithium, cobalt and nickel composite oxides, lithium and manganese composite oxides. The cathode active material can also be mixed with a conductive material (usually carbon) and an appropriate amount of binder and kneaded with a solvent to make a slurry which is then applied to the trap (usually an aluminum trap), then long-dried and compacted to obtain the cathode.

The binder for the cathode may be the same as for the cathode and is preferably based on fluorinated resins.

For these two electrodes, the amount of the binder is usually 1-30 parts by weight relative to 100 parts by weight of the electrode active material, preferably 3-15 parts by weight.

However, as mentioned above, the fluorinated resin, which itself has poor adhesion to the metal (electrode (active material + binder)), is easily separated from the catcher used for the two electrodes, the cathode and the anode, thereby Decrease battery life. JP5-6766 proposes to roughen the surface of the trap to increase the adhesion of the fluorinated resin. Usually, however, this technique cannot obtain sufficient adhesiveness.

The present invention provides an adhesive consisting of the above-mentioned metal-acdhesive composition:

1/ It contains only (a) and (b), the amount of (b) being 0.2-20% by weight of the total weight of the composition,

2/ It contains only (a) and (c), the amount of (c) being 0.5-50% by weight of the total composition,

3/ It contains only (a) and (b) and (c), (b) in an amount of 0.5-20% by weight and (c) in an amount of 0.5-50% by weight of the total composition.

A slurry is obtained by kneading a predetermined amount of an electrode active material and a binder in the presence of a solvent, coating the obtained slurry on a catcher of an electrode and drying the slurry and optionally followed by In the step of press molding, electrodes can be formed. The coated slurry is preferably heat-treated at 60-250°C, more preferably at 80-200°C, for 1 minute to 10 hours. The obtained ribbon electrode can be wound together with the separator sheet to produce a helically wound cylindrical electrode.

The solvent used to prepare the slurry coated on the metal trap can be water and/or organic solvents such as N-methylpyrrolidone, N,N-dimethylformamide, tetrahydrofuran, dimethylacetamide, Dimethyl sulfoxide, hexamethylsulfamate, tetramethylurea, acetone and/or methyl ethyl ketone. Among these solvents, methylpyrrolidone is preferably used. A dispersant, preferably a nonionic dispersant, may also be used if desired.

The present invention will be explained by examples below, but the present invention is not limited in any way by said examples.

Example 1

100 parts by weight of PVDF resin pellets composed of Kynar ^® 710 (sold by the applicant, melting point 170 ° C, MFR = 12 g/10 minutes at 230 ° C / 2.16 kg load), 30 parts by weight of which Malay Polymethyl methacrylate (SumipexTR, manufactured by Sumitomo Chemical Co.) and 70 parts by weight of a hexafluoroacrylic/vinylidene fluoride copolymer ( ^Kynar® 2800, sold by the applicant, sold by the applicant at 230°C/12.5 kg load (MFR=6g/10min, melting point 142°C) into a mixer, after mixing, can use cylinder temperature set at 170-240°C twin-screw extruder by these three ingredients into pellets.

A film (A) of thickness about 0.2 mm, a film of ^Kynar® 710 (B) (thickness 0.3 mm) and a steel plate (C) of thickness about 1 mm produced from these pellets using a single screw extruder were used , these substances were stacked in the order B/A/C and then pressurized at 180°C with a maximum pressure of about 10 kg/ ^cm2 . After cooling to room temperature, a 2 cm wide layer of B/A was torn off from a steel plate at a temperature of 23° C. using a tensile tester at a speed of 100 mm/min. When the force was measured, the bond strength was 2.0 kg/cm.

Example 2

Composition granules composed of three components were prepared in the same manner as in Example 1, except that the proportions in Example 1 were changed to 2 parts by weight of SumipexTR and 5 parts by weight of Kynar® ⁷¹⁰ per 100 parts by weight of Kynar® 710. Kynar 2800. When the adhesive strength between the steel plate and the PVDF resin layer was measured in the same manner as in Example, it was 310 g/cm.

Example 3

100 parts by weight of PVDF resin powder (sold by the applicant as Kynr 310F, melting point 160 °C, MFR = 1.2 g/10 min at 230 °C/12.5 kg load), 1 part by weight of SumipexTR and 1 part by weight of Kynar 2800 were added to In 1000 ml of N-methylpyrrolidone, a homogeneous solution can be obtained by stirring at 30°C for about 24 hours.

This solution was applied to 1 mm thick copper and aluminum plates which had been degreased with toluene, and the solution was dried at 120° C. for 2 hours. The thickness of the PVDF resin layer is about 50 microns. When the PVDF resin layer was cut at intervals of 1 mm and subjected to a cross-cut adhesion test (based on Japanese standard JIS K5400, 6.15) and a tape peel test, no separation of the PVDF resin layer was seen in any of the tests.

Example 4

A solution of a metal-adhesive composition was prepared in the same manner as in Example 3, except that maleic anhydride, N-methyl-dimethylglutarimide, carboxylic acid-containing A copolymer of polymer and methyl methacrylate (Paraloid® EL4151, sold by Rohm and Haas) was used as an acrylic polymer in Example 3 with functional groups having good adhesion properties or affinity with metals. When the adhesive strength was measured in the same manner as in Example 3, no peeling of the PVDF resin layer was seen and the adhesive strength was excellent.

Example 5

A solution of a metal-adhesive composition was prepared in the same manner as in Example 3, except that polymethyl methacrylate that had been grafted with epoxy-modified polymethyl methacrylate was used (Rezeda GP-301, sold by Toagosei Chemical Industry Co., Ltd.) as an acrylic polymer having a functional group having good adhesive properties or affinity with metal in Example 3.

When the adhesive strength was measured in the same manner as in Example 3, no peeling of the PVDF resin layer was seen and the adhesive strength was excellent.

Example 6

A coextruder consisting of a coextrusion head for obtaining a bilayer thermoplastic structure and a twin extruder for supplying the molten resin (extruder A with a pressure ratio of 3.5 and L/D=15) were used. Screw machine, extruder B has a screw machine with a pressure ratio of 4 and L/D=20), extruded PVDF resin (sold by the applicant as ^Kynar® 740) from extruder A, and extruded from extruder A B The adhesive composition obtained in Example 1 was extruded, thereby producing a composite film containing a 0.3 mm PVDF resin layer and a 0.1 mm adhesive layer. The cylinder temperatures of extruders A and B at this time were 170-240°C and 150-220°C, respectively.

When the adhesive property between the obtained film and the steel plate was measured in the same manner as in Example 1, it was 1.9 kg/cm.

Comparative Example 1

100 parts by weight of PVDF resin pellets (composed of ^Kynar® 710, 30 parts by weight of maleic anhydride and methyl methacrylate (Sumipex TR, manufactured by Sumitomo Chemical Co.) were added to a mixer, and after mixing, it was possible to use A twin-screw extruder with a cylinder temperature set at 170-240° C. produced films with a thickness of approximately 0.1 mm.

When the bond strength to the steel plate was measured using this film and a separately prepared Kynar ^® 710 film (thickness 0.3 mm) by the method described above, the value was not more than 1 kg/cm.

Comparative Example 2

100 parts by weight of PVDF resin powder ( ^Kynar® 301F) was dissolved in 1000 ml of N-methylpyrrolidone to form a solution. Then, in the same manner as in Example 3, a PVDF resin layer was formed on the metal plate. When the adhesive performance was evaluated by the cross-cut adhesive test in the same manner as in Example 3, about 80% of the PVDF layer for the copper plate and all the PVDF layers for the aluminum plate were separated due to cutting at 1 mm intervals.

Comparative Example 3

100 parts by weight of Kynar® ^301F and 1 part by weight of Sumipex TR were dissolved in 1000 ml of N-methylpyrrolidone to form a solution. Then, in the same manner as in Example 3, a PVDF resin layer was formed on the aluminum plate. When the bond strength was measured, it was found that about 80% of the PVDF layers did not peel in the cross-cut test, while in the tape peel test all the PVDF layers separated.

Example 7

By adding 10 parts by weight of polyvinylidene fluoride-Kynar ^® 500 and 0.1 parts by weight of methacrylate copolymer containing 100 parts by weight of methyl methacrylate and 10 parts by weight of maleic anhydride (at 230 ° C / 3.8 kg MRF = 2.4 g/min) dissolved in N-methylpyrrolidone. Then, 90 parts by weight of coal coke crushed in a ball mill was added to the solution as an anode active material to obtain a slurry (slurry). The slurry was coated on both sides of a copper foil with a thickness of 20 microns, heated at 120°C for 1 hour, dried under reduced pressure and then press-molded to obtain a cathode with a thickness of 140 microns and a width of 20 mm.

The preparation process of the cathode is as follows:

90 parts by weight of _LiCoO2 as the cathode active material, 6 parts by weight of graphite as the conductive additive, 10 parts by weight of PVDF as the binder and 0.1 parts by weight of the above-mentioned methyl methacrylate-maleic anhydride copolymer were mixed and dispersed in N-formaldehyde base pyrrolinone to obtain a slurry. The slurry was coated on both sides of an aluminum foil with a thickness of 20 microns, heated at 120° C. for 1 hour, dried under reduced pressure and then press-molded to obtain an anode with a thickness of 170 microns and 20 mm.

It can be seen that there is good adhesion between the electrode and the trap: the trap cannot be detached from the electrode surface when peeled off with a dicing knife.

The obtained cathode and anode are laminated together alternately through a porous polyacrylic film with a thickness of 25 micrometers as a separator, thereby forming a sandwich material of separator/cathode/separator/anode/separator, which is spirally winding to obtain a cylindrical electrode assembly. After connecting the lead wires to the respective electrodes, the electrode assembly is packaged in a stainless steel container into which the electrolyte is poured. The electrolyte is a 1 M solution of _LiPF6 dissolved in an equal volume of a mixture of carbonate acrylate and 1,2-dimethoxyethane.

A charge-discharge test was performed: the battery was charged to 4.1 V with a current density of 30 mA/1 g of carbon, and then discharged to 2.5 V with the same current. The same charge-discharge operation was repeated to evaluate the discharge capability. The discharge capacity after 100 cycles was 90% of the value at the 10th cycle.

Example 8

The procedure of Example 7 was repeated, but the methacrylate copolymer was replaced by a block consisting of methyl methacrylate blocks and copolymer blocks comprising methyl methacrylate and acrylic acid (acrylic acid content 5% by weight). segment copolymer, and a copolymer of vinylidene fluoride and hexafluoroacrylic (sold as ^Kynar® 2800 by the applicant) was used as the PVDF resin to prepare the anode and cathode.

It was found that there was good adhesion between the electrode and the trap: the trap could not be detached from the electrode surface when peeled off with a dicing knife.

A battery was prepared in the same manner as in Example 1 and subjected to the same charge-discharge test. The charging capacity after 100 cycles is 85% of the value at the 10th cycle.

Comparative Example 4

In preparing the anode and cathode, the same procedure as in Example 7 was repeated without adding the methacrylate copolymer to the slurry.

When the stripping was performed with a dicing knife, no part of the catcher remained on the electrode.

A battery was prepared in the same manner as in Example 7 and subjected to the same charge-discharge test. After 100 cycles, the discharge capacity was 50% of the value at the 10th cycle.

Example 9

By adding 10 parts by weight of polyvinylidene fluoride-Kynar ^® 500 and 0.3 parts by weight of a copolymer of vinylidene fluoride and hexafluoroacrylic acid (the content of hexafluoroacrylic acid is 10% by weight, the product of Elf Atochem, Kynar ^® 2800 , MRF = 1.0 g/10 min at 230 °C and a load of 2.16 kg) dissolved in N-methylpyrrolidone. Then, 90 parts by weight of coal coke crushed in a ball mill was added to the solution as an anode active material to obtain a slurry (slurry). The slurry is coated on both sides of a copper foil (its surface has been rough ground with Emery paper No.1000 in advance) with a thickness of 20 microns, heated at 120° C. for 1 hour, dried under reduced pressure and then press-molded, A cathode with a thickness of 140 microns and a width of 20 mm is obtained.

The cathode was prepared as follows: 90 wt. parts of _LiCoO2 as the cathode active material, 6 wt. parts of graphite as the conductive additive, 10 wt. parts of the same PVDF and 0.3 wt. -Methylpyrrolidone to obtain a slurry. The slurry was coated on both sides of an aluminum foil with a thickness of 20 microns (its surface had been rough ground with Emery paper No.1000 in advance), heated at 120°C for 1 hour, dried under reduced pressure and then press-molded to obtain Anode with a thickness of 165 microns and 20 mm.

It can be seen that there is good adhesion between the electrode and the trap: the trap cannot be detached from the electrode surface when peeled off with a dicing knife.

The obtained cathode and anode are laminated together alternately through a porous polyacrylic film with a thickness of 25 micrometers as a separator, thereby forming a sandwich material of separator/cathode/separator/anode/separator, which is spirally winding to obtain a cylindrical electrode assembly. After connecting the lead wires to the respective electrodes, the electrode assembly is packaged in a stainless steel container into which the electrolyte is poured. The electrolyte is a 1 M solution of _LiPF6 dissolved in an equal volume of a mixture of carbonate acrylate and 1,2-dimethoxyethane.

A charge-discharge test was performed: the battery was charged to 4.1 V with a current density of 30 mA/1 g of carbon, and then discharged to 2.5 V with the same current. The same charge-discharge operation was repeated to evaluate the discharge capability. The discharge capacity after 100 cycles was 90% of the value at the 10th cycle.

Example 10

The process of Example 9 was repeated, but the vinylidene fluoride copolymer was replaced by a copolymer of vinylidene fluoride and tetrafluoroethylene ( ^Kynar® 2820, the content of tetrafluoroethylene was 27%, at 230 ° C and a load of 2.16 kg The MFR is 3 g/10 min) to prepare the anode and cathode.

It was found that there was good adhesion between the electrode and the trap: the trap could not be detached from the electrode surface when peeled off with a dicing knife.

A battery was prepared in the same manner as in Example 9 and subjected to the same charge-discharge test. The charging capacity after 100 cycles is 85% of the value at the 10th cycle.

Comparative Example 5

The procedure of Example 9 was repeated, but no vinylidene fluoride copolymer was added to the slurry for electrodes.

When peeling off with a dicing knife, no part of the catcher could remain on the electrode surface.

A battery was prepared in the same manner as in Example 9 and subjected to the same charge-discharge test. The charging capacity after 100 cycles is 60% of the value at the 10th cycle.

Example 11

By adding 10 parts by weight of PVDF-Kynar ^® 500, 0.1 parts by weight of a methacrylate copolymer composed of 100 parts by weight of methyl methacrylate and 10 parts by weight of maleic anhydride (MRF=2.4 at 230° C./3.8 kg) g/10 min) and 0.1 part by weight of a copolymer of vinylidene fluoride and hexafluoroacrylic acid (Kynar® ²⁸⁰⁰ , MFR=0.2 g/10 min at 230°C and a load of 2.16 kg) dissolved in N-methylpyrrole in ketones. Then, 90 parts by weight of coal coke crushed in a ball mill was added to the solution as an anode active material to obtain a slurry (slurry). The slurry was coated on both sides of a copper foil with a thickness of 20 microns, heated at 120° C. for 1 hour, dried under reduced pressure and then press-molded to obtain a cathode with a thickness of 145 microns and a width of 20 mm.

The cathode was prepared as follows: 90 parts by weight of _LiCoO2 as the cathode active material, 6 parts by weight of graphite as the conductive additive, 10 parts by weight of PVDF and 0.1 parts by weight of the above-mentioned methyl methacrylate copolymer and 0.1 parts by weight of the above-mentioned vinylidene fluoride and hexafluoroacrylic copolymer as a binder and dispersed in N-methylpyrrolidone to obtain a slurry. The slurry was coated on both sides of an aluminum foil with a thickness of 20 microns, heated at 120° C. for 1 hour, dried under reduced pressure and then press-molded to obtain an anode with a thickness of 175 microns and 20 mm.

It can be seen that there is good adhesion between the electrode and the trap: the trap cannot be detached from the electrode surface when peeled off with a dicing knife.

The obtained cathode and anode are laminated together alternately through a porous polyacrylic film with a thickness of 25 micrometers as a separator, thereby forming a sandwich material of separator/cathode/separator/anode/separator, which is spirally winding to obtain a cylindrical electrode assembly. After connecting the lead wires to the respective electrodes, the electrode assembly is packaged in a stainless steel container into which the electrolyte is poured. The electrolyte is a 1 M solution of _LiPF6 dissolved in an equal volume of a mixture of carbonate acrylate and 1,2 dimethoxyethane.

A charge-discharge test was performed: the battery was charged to 4.1 V with a current density of 30 mA/1 g of carbon, and then discharged to 2.5 V with the same current. The same charge-discharge operation was repeated to evaluate the discharge capability. The discharge capacity after 100 cycles was 95% of the value at the 10th cycle.

Example 12

The procedure of Example 11 was repeated, but the methacrylic acid was replaced by a block copolymer consisting of a methyl methacrylate block and a copolymer block consisting of methyl methacrylate and acrylic acid (5% acrylic acid content) Ester copolymers and replacement of fluorinated copolymers with copolymers of vinylidene fluoride copolymers and tetrafluoroethylene (tetrafluoroethylene content 27%, MFR 3 g/10 min at 230 °C and 2.16 kg load) , to prepare the anode and cathode.

It was found that there was good adhesion between the electrode and the trap: the trap could not be detached from the electrode surface when peeled off with a dicing knife.

A battery was prepared in the same manner as in Example 11 and subjected to the same charge-discharge test. The charging capacity after 100 cycles is 92% of the value at the 10th cycle.

Comparative Example 6

The procedure of Example 1 was repeated except that the methacrylate copolymer and the fluorinated copolymer were not added to the slurry during the preparation of the anode and cathode.

When stripping was performed with a dicing knife, no trap remained on the electrode surface.

A battery was prepared in the same manner as in Example 11 and subjected to the same charge-discharge test. The charging capacity after 100 cycles is 50% of the value at the 10th cycle.

Claims (9)

1. A metal-adhesive fluorinated composition comprising at least two of the following three components: (a) at least one PVDF resin, (b) at least one acrylic and/or methacrylic polymer with functional groups having adhesion or affinity for metals, (c) at least one vinylidene fluoride copolymer resin. 2. According to the composition of claim 1, per 100 parts by weight of polyvinylidene fluoride resin (a), it contains 0.5-100 parts by weight of acrylic and/or methacrylic polymer (b), 1-200 parts by weight Vinyl difluoride copolymer resin (c). 3. A method for bonding metals and fluorinated resins, characterized in that the composition according to claim 1 or 2 is used as an adhesive between the fluorinated resins and the metal. 4. A method for bonding metals and fluorinated resins, characterized in that any one of the compositions as claimed in claim 1 or 2 is used instead of the fluorinated resin coated on the metal. 5. The electrode adhesive made of the composition according to claim 1, which only contains (a) and (b), and the amount of (b) is 0.5-20% by weight of the total weight of the adhesive. 6. The electrode adhesive made of the composition according to claim 1, which only contains (a) and (c), and the amount of (c) is 0.5-50% by weight of the total weight of the adhesive. 7. The electrode adhesive made of the composition according to claim 1 or 2, which only contains (a), (b) and (c), and the amount of (b) is 0.5-20% of the total weight of the adhesive % by weight, and the amount of (c) is 0.5-50% by weight of the total weight of the adhesive. 8. An electrode comprising a metal trap coated on an electrode comprising an active material and a binder according to any one of claims 5-7. 9. Accumulator and/or battery comprising at least one electrode as defined in claim 8, preferably a lithium-ion accumulator and/or battery.