CN114919257A

CN114919257A - Metal composite film of outer packaging material for lithium ion battery device

Info

Publication number: CN114919257A
Application number: CN202210524986.7A
Authority: CN
Inventors: 庄志; 张茜; 黎秋生; 蔡裕宏; 程跃
Original assignee: Jiangsu Ruijie New Material Technology Co ltd
Current assignee: Jiangsu Ruijie New Material Technology Co ltd
Priority date: 2022-05-13
Filing date: 2022-05-13
Publication date: 2022-08-19
Also published as: WO2023216410A1

Abstract

The metal composite film provided by the invention comprises a metal layer, an inner-layer bonding layer, a hot-melt resin layer, an outer-layer bonding layer and an outer layer, wherein the outer layer is arranged on one side of the metal layer, the hot-melt resin layer is arranged on the other side of the metal layer, the inner-layer bonding layer is arranged between the metal layer and the first hot-melt resin layer, the outer-layer bonding layer is arranged between the outer layer and the metal layer, anti-corrosion layers can be respectively arranged on two sides of the metal layer, and the hot-melt resin layer is of a layer structure formed by fluorine-containing resin insert-forging or random copolymerization of other polar groups. The metal composite film has high heat sealing strength and good tolerance when being formed into a soft package battery.

Description

Metal composite film of outer packaging material for lithium ion battery device

Technical Field

The present invention relates to the technical field of battery packaging materials, and particularly to a metal composite film for an outer packaging material of a lithium ion battery device.

Background

At present, lithium ion batteries are mainly divided into three types, namely square, cylindrical and soft package, wherein the square and cylindrical shells mainly adopt hard shells made of aluminum alloy, stainless steel and the like, the aluminum alloy shells can be made of aluminum, and the soft package shell formed by laminating metal and resin adopts a metal composite film, so that the problem of inflexible appearance design of hard-package batteries is greatly improved.

The metal composite film mainly has two product types, namely a dry product, namely an outer base material resin layer, an outer bonding layer, an intermediate metal layer, an inner bonding layer and a hot-melt bonding resin layer are sequentially formed from outside to inside. In the other type, the outer base resin layer, the outer adhesive layer, the intermediate metal layer and the inner heat-fusible resin layer are formed in this order from the outside to the inside as the outer battery casing.

At present, higher requirements are provided for the high temperature resistance, corrosion resistance, durability and safety of the battery to an outer packaging material, on one hand, 3C products can generate certain heat in the charging and discharging process, power lithium ion batteries can generate more heat, the service life of 3C equipment is 2-5 years and is shorter, and on the other hand, EV power supplies require more than 10 years of service life performance, and the long-term service life is also deficient; on the other hand, lithium ion batteries are frequently involved in ignition accidents, and problems in safety still remain, and all-solid-state batteries, which are intrinsically safe, thin, lightweight, flexible, and long-life, have been proposed and developed. The high temperature resistance of the all-solid battery to the outer packaging material is higher than that of the lithium ion battery. At present, modified polypropylene is mainly used as an inner adhesive layer in the market, and the melting point of the modified polypropylene is between 70 and 80 ℃; the polypropylene is used as an internal heat welding resin layer, the melting point of the polypropylene is between 140 and 160 ℃, and the polypropylene material has the advantages of stress whitening resistance, puncture resistance and excellent bending resistance. The product characteristics of the metal composite film are used at present, so that certain defects exist in the aspects of heat resistance, corrosion resistance, durability and safety of the metal composite film. The swelling of electrolyte can take place, and electrolyte infiltration reduces the stable work of the inside chemical system of battery, can blow and split under the severe condition, and the bad condition of insulating nature can appear, seriously influences the safety in utilization. The use requirement of the all-solid-state battery of the next generation product can not be met, and the battery can be used under the condition of high temperature. Considering the use of fluororesin with higher melting point, the H atoms on the main chain or side chain of the fluorine-containing polymer molecule are partially or completely replaced by F, the special structure enables the fluorine-containing polymer to have special properties which other polymers do not have, the bond energy of C-F bonds is as high as 485 kJ/mol, and is far higher than the bond energy of C-H bonds, and the bond energy is the largest chemical bond in all covalent single bonds. In addition, the shielding effect of the electron cloud of the F atom on the C-C bond is stronger than that of the H atom, so that the C-C bond on the main chain can be well protected from the external influence, and the fluorine-containing polymer has excellent oxidation resistance, corrosion resistance, weather resistance, low friction, low refraction, low capacitance, low surface energy, low moisture absorption and other properties due to the existence of a large C-F bond group, and is more excellent in heat resistance, corrosion resistance and durability. However, the heat seal layer cannot be independently used is mainly difficult in heat seal and poor in fluidity, two films in heat seal contact cannot be well fused during heat seal, so that the heat seal strength is low, and on the other hand, the heat seal needs high temperature because the melting point is too high. Because the melting point of the NY of the outer layer is 220 ℃, the NY is melted and damaged, the existing heat sealing process can not dissolve and heat seal, and therefore, the outer layer material is made of a high-temperature resistant material, and can be selected from fluorine resin, polyimide resin and the like.

Disclosure of Invention

The present invention provides a metal composite film, which comprises: a metal level, an inlayer adhesive linkage, a hot melt resin layer, an outer adhesive linkage and an skin, the skin sets up in metal level one side, the hot melt resin layer sets up in the metal level opposite side, the inlayer adhesive linkage set up in the metal level with between the first hot melt resin layer, outer adhesive linkage set up in between skin and the metal level, the metal level both sides can be provided with two-layer anti-corrosion coating, the hot melt resin layer is fluorine-containing resin and inlays the layer structure of forging or random copolymerization polarity group formation.

Optionally, the fluorine-containing resin is any one or more of tetrafluoroethylene resin, vinylidene fluoride resin, and copolymer of tetrafluoroethylene and ethylene, tetrafluoroethylene and perfluoroalkyl ether.

Optionally, the polar group is any one or more of an acidic group, a halogen, an epoxy group and an ether group; preferably, the acid group can be any one or more of maleic anhydride, fumaric acid and itaconic acid, and the ether group can be any one or more of polyvinyl methyl ether and polyvinyl ethyl ether.

Optionally, the outer layer is any one or more of a fluorine resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a urea resin, an epoxy resin, an acrylic resin, a polyamide resin, a polyimide resin, a polyamideimide resin, a polyurethane resin, and a phenolic resin.

Optionally, the outer adhesive layer is a two-component polyurethane adhesive formed by using polyester polyol, polyurethane modified polyol and the like as diol main agents and using aromatic or aliphatic isocyanate as a curing agent. The curing agent may be selected according to the functional group of the adhesive component, and may be appropriately selected from a polyfunctional epoxy resin, a methanesulfonic acid-containing polymer, a porlyamine resin, an inorganic acid, and the like. The combination of the outer adhesive layer more preferably in the invention is binary or multi-component polyester, one or two of polyurethane modified polyester and isocyanate. The isocyanate is not particularly specified in the compounds having two or more isocyanate groups in the molecule. For example, one or a mixture of two or more of polymers such as isophorone diisocyanate (IPDI), Toluene Diisocyanate (TDI), diphenylmethane-4, 4' -diisocyanate (MDI), and 1, 6-Hexamethylene Diisocyanate (HDI).

Optionally, the inner layer adhesive layer is one or more of the fluororesin, the propylene resin, and the propylene-ethylene copolymer is composed of a copolymer of a polypropylene resin and an ethylene resin, which contains a functional group that thermally reacts with the anticorrosive layer. Preferably, the inner adhesive layer resin is modified with a modifying group, wherein the modifying group is any one or more of carboxyl, acid anhydride, acid halide, epoxy, hydroxyl, amino, mercapto, carbonate bond, amide bond, urethane bond and urea bond.

Optionally, the metal layer may be subjected to an anti-corrosion treatment to form an anti-corrosion layer on each of both sides of the metal layer.

According to the invention, a small amount of polar molecules are introduced to a linear fluororesin chain, block copolymerization or random copolymerization is carried out to destroy the symmetry of the linear fluororesin chain, so that MFR is improved to be more than 20g/10 min, the better the flow property of the material is realized more easily by heat sealing, and the heat sealing effect is good.

Drawings

Fig. 1 is a schematic cross-sectional structure of a metal composite film in example 1, to show a metal composite film according to an embodiment of the present invention; wherein the content of the first and second substances,

1. an outer layer;

2. an outer tie layer;

3. an anti-corrosion layer;

4. a metal layer;

5. an anti-corrosion layer;

6. an inner tie layer;

7. and thermally fusing the resin layer.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The specific embodiment of the invention provides an outer packaging material for a battery device, which comprises an outer layer 1, an outer bonding layer 2, an anti-corrosion layer 3, a metal layer 4, an anti-corrosion layer 5, an inner bonding layer 6 and a heat fusion resin layer 7, wherein the anti-corrosion layer 3 and the anti-corrosion layer 5 are formed after the two surfaces of the metal layer 4 are subjected to anti-corrosion treatment, the outer bonding layer 2 is arranged between the outer layer 1 and the anti-corrosion layer 3, and the inner bonding layer 6 is arranged between the anti-corrosion layer 5 and the heat fusion resin layer 7.

Outer layer 1:

the outer layer 1 is required to have a resistance to a high heat-sealing temperature, and in the present invention, the outer layer is a single-layer or multi-layer structure of any resin having a softening temperature of 180 ℃ or higher or a melting point of 230 ℃ or higher.

Outer adhesive layer 2:

the outer adhesive layer is a two-component polyurethane adhesive formed by using polyester polyol, polyurethane modified polyol and the like as main diol agents and using aromatic or aliphatic isocyanate as a curing agent. The curing agent may be selected according to the functional group of the adhesive component, and may be appropriately selected from a polyfunctional epoxy resin, a methanesulfonic acid-containing polymer, a poloxamine resin, an inorganic acid, and the like. The combination of the outer adhesive layer more preferably in the invention is binary or multi-component polyester, one or two of polyurethane modified polyester and isocyanate. The isocyanate is not particularly specified in the compounds having two or more isocyanate groups in the molecule. For example, one or a mixture of two or more of polymers such as isophorone diisocyanate (IPDI), Toluene Diisocyanate (TDI), diphenylmethane-4, 4' -diisocyanate (MDI), and 1, 6-Hexamethylene Diisocyanate (HDI).

Metal layer 4:

the metal material used for the intermediate metal layer may be specifically an aluminum alloy, stainless steel, titanium steel, nickel-plated iron plate, or the like, and when used as a metal foil, it may be one or more layers. Preferably, the steel sheet contains at least one of aluminum alloy foil, nickel-plated iron plate, and stainless steel foil.

Inner layer adhesive layer 6:

the inner layer adhesive layer is one or more of the fluororesin, the propylene resin and the propylene-ethylene copolymer resin, and the propylene-ethylene copolymer is composed of a copolymer of a polypropylene resin and an ethylene resin, which contains a functional group that thermally reacts with the anticorrosive layer. Preferably, the inner adhesive layer resin is modified with a modifying group, which is any one or more of a carboxyl group, an acid anhydride group, an acid halide group, an epoxy group, a hydroxyl group, an amino group, a mercapto group, a carbonate bond, an amide bond, a urethane bond, and a urea bond.

Corrosion prevention layer 3, corrosion prevention layer 5:

the metal layer 4 is subjected to corrosion prevention treatment on two sides to form a corrosion prevention layer 3 and a corrosion prevention layer 5. Various anticorrosive solutions mainly containing phosphates, nitric acid, chromates, fluorides, rare earth oxides, and the like have been known. Chemical conversion treatments using phosphates and chromates mainly include, for example, chromium chromate treatment, chromium phosphate treatment, phosphoric acid-chromate treatment, and the like, and examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, chromium acetate, chromium chloride, and chromium sulfate. The chromate treatment method mainly includes etching chromate treatment, electrolytic chromate treatment, coating chromate treatment, and the like, but coating chromate treatment is preferable. In the coating chromate treatment, a treatment liquid mainly containing a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, Zn (lead) phosphate, or the like and a mixture of these metal salts, or a treatment liquid mainly containing a non-metal phosphate and a mixture of these non-metal salts is mixed with a synthetic resin on the degreased surface to form a treatment liquid, and the treatment liquid is coated by a known coating method such as a roll coating method, a gravure printing method, an immersion method, or the like, and dried. Various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester compound solvents, and ether solvents can be used as the treatment liquid, but water is preferred. As the resin component used in the present invention, a water-soluble polymer such as an aminated phenol or a polyacrylic acid-based resin can be selected.

Heat-fusion resin layer 7:

the thermal welding resin layer is a layer structure formed by fluorine-containing resin block forging or random copolymerization of other polar groups.

The fluorine-containing resin is any one or more of tetrafluoroethylene resin, vinylidene fluoride resin, and a copolymer of tetrafluoroethylene and ethylene, tetrafluoroethylene and perfluoroalkyl ether.

The fluorine-containing resin is a copolymer of tetrafluoroethylene, ethylene and a polar group, wherein the content of the tetrafluoroethylene can be more than 50%, and the mass ratio of the tetrafluoroethylene to the ethylene is 60:40, preferably 55: 45.

The heat-fusible resin layer 7 may be a copolymer of tetrafluoroethylene, ethylene and perfluoro (alkyl vinyl ether) with a polar group, the perfluoroalkyl ether has a side group of Rf, and the crystallinity of the polymer is significantly reduced after a small amount of comonomer enters the polymer structure, mainly because the introduced side group destroys the regularity of the main chain. The thickness of a crystal-forming wafer is greatly reduced along with the increase of the content of the perfluoroalkyl ether, when a large amount of comonomer enters a polymer structure, the crystallinity of the polymer is remarkably reduced and even becomes an amorphous structure, a certain crystallinity is required for achieving the barrier property of an internal heat welding resin layer, the electrolyte solution resistance is improved through a compact structure, the content of the perfluoroalkyl ether is controlled to be below 4 percent, the content of polar groups is 0.1 to 10 percent (based on the total mole number of tetrafluoroethylene, ethylene and the perfluoroalkyl ether), and the mass ratio of the tetrafluoroethylene and the ethylene is 40:55 to 55: 40.

The heat-sealing resin layer 7 may be tetrafluoroethylene, a block copolymer of perfluoroalkyl ether and alkenyl ether. Wherein, the mass ratio of the tetrafluoroethylene to the perfluoro (alkyl vinyl ether) is 60:40, and the content of the vinyl ether is 1-10% (based on the total mole number of the tetrachloroethylene and the perfluoroalkyl ether).

The vinyl ether can be polyvinyl methyl ether, polyvinyl ethyl ether and the like, 1 percent of vinyl ether is enough to obviously reduce the crystallinity of the tetrafluoroethylene, perfluoroalkyl ether copolymer chain segment and ensure that the melt viscosity is low, thereby being convenient for melt processing; this is associated with a change in the conformation of the chain, which even in the melt assumes a stretched conformation, increasing the mobility of the chain segment after the introduction of the non-fluorine group, thus causing it to undergo a transition corresponding to a transition from a stretched conformation to a crimped conformation well below the decomposition temperature, i.e. slightly above its melting temperature Tm.

The polar group may be an acidic group, and may also be a halogen, an epoxy, an ether group, or the like, and preferably, the acidic group may be: maleic anhydride, fumaric acid, itaconic acid, and the like.

Example 1:

provided is a metal composite film including:

outer layer 1: a biaxially oriented polyimide film having a thickness of 25 um;

outer adhesive layer 2: the outer adhesive layer is a two-component polyurethane adhesive formed by using polyester polyol, polyurethane modified polyol and the like as main diol agents and aliphatic isocyanate as a curing agent.

Corrosion-resistant layer 3, corrosion-resistant layer 5: performing anticorrosion treatment on the alloy by using an anticorrosion solution, wherein the anticorrosion solution comprises a trivalent chromium compound, inorganic acid and organic resin, and the content ratio is 2: 2: 1, the trivalent chromium compound is chromic phosphate, the inorganic acid is nitric acid, the organic resin is polyacrylic resin, a crosslinking agent which is subjected to thermal reaction with the inner layer adhesive resin is added into the anticorrosive layer, and the crosslinking agent is amino resin.

Metal layer 4: an 8021 aluminum material with surface wettability of 68dyn/cm and thickness of 35 um;

inner bonding layer 6: the inner layer adhesive layer is formed by a copolymer of propylene and ethylene, and the copolymer of polypropylene resin and ethylene resin contains a functional group which is thermally reacted with the anticorrosive layer. The modifying group of the modified resin for forming the inner adhesive layer resin layer is maleic anhydride, and the curing agent is a multifunctional isocyanate curing agent.

And a heat-fusion resin layer 7: the hot welding resin layer is a copolymer formed by tetrafluoroethylene, ethylene and maleic anhydride block copolymer, the three macromolecules are connected end to end, and the thickness of the internal hot welding resin layer is 80 um.

The heat welding resin layer is a block copolymer of tetrafluoroethylene and ethylene and maleic anhydride. The copolymer is formed by connecting the three macromolecules head to tail, wherein the content of tetrafluoroethylene is 60%, and the mass ratio of tetrafluoroethylene to ethylene is 55: 45. The maleic anhydride content was 6% (based on the total number of moles of tetrachloroethylene and ethylene). The block copolymer resin of tetrafluoroethylene and ethylene with maleic anhydride had a melting point of 240 ℃ and a melt viscosity (MFR) of 20g/10 min as measured at a temperature of 50 ℃ relative to the melting point. The heat seal strength at 120 ℃ was 110N.

Example 2:

provided is a metal composite film including:

outer layer 1: the thickness of the biaxially oriented polyimide film is 25 um;

outer adhesive layer 2: the outer adhesive layer is a two-component polyurethane adhesive formed by using polyester polyol, polyurethane modified polyol and the like as diol main agents and aliphatic isocyanate as a curing agent.

Corrosion-resistant layer 3, corrosion-resistant layer 5: carrying out anticorrosion treatment on the alloy by using an anticorrosion solution, wherein the anticorrosion solution comprises a trivalent chromium compound, inorganic acid and organic resin, and the content ratio is 2: 2: 1, the trivalent chromium compound is chromic phosphate, the inorganic acid is nitric acid, the organic resin is polyacrylic resin, a crosslinking agent which is subjected to thermal reaction with the inner layer adhesive resin is added into the anticorrosive layer, and the crosslinking agent is amino resin.

Metal layer 4: an 8021 aluminum material having a surface wettability of 68dyn/cm and a thickness of 35 um;

inner bonding layer 6: the inner layer adhesive layer is formed by copolymer of propylene and ethylene, and the copolymer of polypropylene resin and ethylene resin contains functional groups which are thermally reacted with the anticorrosive layer. The modifying group of the modified resin for forming the inner adhesive layer resin layer is maleic anhydride, and the curing agent is a multifunctional isocyanate curing agent.

And, heat-fusion resin layer 7: the heat-sealing resin layer 7 is a block copolymer of tetrafluoroethylene, ethylene, perfluoroalkyl ether and maleic anhydride as an internal heat-sealing resin layer. The four macromolecules are connected end to form a copolymer

The perfluoroalkyl ether content was controlled to 3% or less, the maleic anhydride content was 6% (based on the total number of moles of tetrafluoroethylene, ethylene and perfluoroalkyl ether), the mass ratio of tetrafluoroethylene and ethylene was 55:40, the block copolymer of tetrafluoroethylene, ethylene and perfluoroalkyl ether with maleic anhydride had a melting point of 230 ℃ and a melt viscosity (MFR) measured at a temperature of 50 ℃ relative to the melting point of 30g/10 min. The thickness of the inner heat-sealing resin layer was 80 um.

The heat seal strength at 120 ℃ is 110N,

example 3:

provided is a metal composite film including:

outer layer 1: a biaxially oriented polyimide film having a thickness of 25 um;

Corrosion-resistant layer 3, corrosion-resistant layer 5: carrying out anticorrosion treatment on the alloy by using an anticorrosion solution, wherein the anticorrosion solution comprises a trivalent chromium compound, inorganic acid and organic resin, and the content ratio is 2: 2: 1, adding a crosslinking agent which is amino resin and thermally reacts with the inner layer adhesive resin into the anticorrosive layer, wherein the trivalent chromium compound is chromium phosphate, the inorganic acid is nitric acid, the organic resin is polyacrylic resin, and the crosslinking agent is amino resin.

inner bonding layer 6: the inner layer adhesive layer is formed by a copolymer of propylene and ethylene, and the copolymer of polypropylene resin and ethylene resin contains a functional group which is thermally reacted with the anticorrosive layer. The modified group of the modified resin for forming the inner layer adhesive layer resin layer is maleic anhydride, and the curing agent is a multifunctional isocyanate curing agent.

And, heat-fusion resin layer 7: the heat-sealing resin layer 7 is a block copolymer of tetrafluoroethylene, perfluoroalkyl ether and alkenyl ether. The three macromolecules are connected end to form the copolymer. Wherein the mass ratio of tetrafluoroethylene to perfluoro (alkyl vinyl ether) is 60:40, and the vinyl ether content is 6% (based on the total moles of tetrachloroethylene and perfluoroalkyl ether). The melting point of the resin was 240 ℃ and the melt viscosity (MFR) measured at a temperature of 50 ℃ relative to the melting point was 23g/10 min. The thickness of the internal heat fusion resin layer is 80 um. The heat seal strength at 120 ℃ was 100N.

Example 4:

provided is a metal composite film including:

outer layer 1: a biaxially oriented polyimide film having a thickness of 25 um;

Corrosion prevention layer 3, corrosion prevention layer 5: carrying out anticorrosion treatment on the alloy by using an anticorrosion solution, wherein the anticorrosion solution comprises a trivalent chromium compound, inorganic acid and organic resin, and the content ratio is 2: 2: 1, the trivalent chromium compound is chromic phosphate, the inorganic acid is nitric acid, the organic resin is polyacrylic resin, a crosslinking agent which is subjected to thermal reaction with the inner layer adhesive resin is added into the anticorrosive layer, and the crosslinking agent is amino resin.

And, heat-fusion resin layer 7: the heat-sealing resin layer 7 is tetrafluoroethylene, ethylene and acrylic resin random copolymer. The three macromolecules are subjected to free radical type addition random copolymerization reaction, molecular chains are tetrafluoroethylene, and ethylene and acrylic acid are randomly connected to form a non-uniform copolymer. The mass ratio of tetrafluoroethylene to ethylene was 55: 45. The content of acrylic acid was 5% (based on the total molar number of tetrachloroethylene and ethylene). The melting point of the random copolymer resin of tetrafluoroethylene, ethylene and acrylic resin was 220 ℃ and the melt viscosity (MFR) measured at a temperature of 50 ℃ relative to the melting point was 26g/10 min. The thickness of the inner heat-sealing resin layer is 80um, and the heat-sealing strength is 90N at 120 ℃.

Comparative example 1

The outer base material resin layer/outer adhesive layer (3 mu m)/aluminum alloy foil layer is prepared by the method and is used as a composite outer base material resin composite film, and the inner adhesive layer and the inner heat-sealing layer form an aluminum-plastic composite film.

The thickness of the internal heat fusion resin layer was 80 μm, and the melting point of the internal layer fusion resin was 142 ℃ for random polypropylene (r-pp), 18 parts by weight of acid-modified polypropylene modified with maleic anhydride and homopolypropylene (h-pp) having a melting point of 162 ℃, and the melting point of the resin modified with maleic anhydride was 155 ℃. The melting point of the inner layer welding resin is 135 ℃. The MFR was 7.0g/10 min (230 ℃ C.).

Comparative example 2

According to the method, the outer base material resin layer/outer layer adhesive layer (3 um)/aluminum alloy foil layer is prepared to serve as a composite outer base material resin composite film, and the composite outer base material resin composite film, the inner layer adhesive layer and the inner heat welding resin layer form an aluminum-plastic composite film.

The inner heat-sealing resin layer is generated by copolymerization reaction initiated by tetrafluoroethylene and ethylene free radical. The degree of alternation of the polymer is high, with a tetrafluoroethylene content of 60% and an alternating sequence content of 88%, so that it has a high melting point and crystallinity, with a melting point close to 270 ℃. The thickness of the inner heat-sealing resin layer was 80 um.

Comparative example 3

The internal heat welding resin layer is polyvinylidene fluoride resin. Wherein the fluorine content is 59%, the crystallinity is about 60%, the melting point is 170 ℃ and the melt viscosity (MFR) measured at a temperature of 50 ℃ relative to the melting point is 10g/10 min. The thickness of the internal heat fusion resin layer is 80 um.

Comparative example 4

According to the method, the outer base material resin layer/outer layer adhesive layer (3 um)/aluminum alloy foil layer is prepared to be used as a composite outer base material resin composite film, and the aluminum-plastic composite film is formed with the inner layer bonding layer and the inner heat fusion layer.

The internal heat-sealing resin layer is polypropylene, the polypropylene resin is random polypropylene (r-pp) resin with the melting point of 135 ℃, MFR of 7.0g/10 min (230 ℃) and the melting point of 160 ℃, MFR2.0g/10 min (230 ℃) of 30 parts by weight of block polypropylene (b-pp) resin, the melting point of 124 ℃, MFR: 30 parts by weight of a random polypropylene (r-pp) resin having a melting point of 124 ℃ and 40 parts by weight of an ethylene-polypropylene elastomer having a melting point of 124 ℃, the melting point of the resin being 130 ℃ and the MFR being 12.0g/10 min (230 ℃). The thickness of the internal heat fusion resin layer is 80 um.

The composite films of the examples and comparative examples were tested according to the following methods.

The test method comprises the following steps:

heat seal Strength (80/120 ℃ C.) test method:

a heat sealing machine: rich customization device

A heating seat: (pressure 10KN) the pressure intensity is: 0.84MPa, the melting point of the aluminum bronze 1035 ℃, stable mechanical property at the temperature of 500 ℃, 600MPa of tensile strength, and 200-250 of Rockwell hardness;

sealing a knife: pressure 10KN, width 7mm) the pressure intensity is: 4.76MPa, the melting point of the nickel-chromium alloy is 1350 ℃, the maximum service temperature is 1150 ℃, the tensile strength is 650MPa, and the pressure born by the sealing cutter is far less than the tensile strength of the nickel-chromium alloy

A tensile machine: shimadzu, AGS-X-10 KN.

The beginning of the sample (roll) was removed to ensure that the sampling site was smooth and wrinkle free. Taking 1 sample (N is 1) at M, MC, C, GC and G, respectively, wherein the sampling positions are uniformly distributed in the TD direction of the sample, the sample size TD76mm is more than MD200mm, the glove is worn in the operation process, and the samples of different models and batches are marked. And opening the heat sealing machine to set the temperature, time and surface pressure of the upper sealing knife and the lower sealing knife. The hot melt face of sample is folded in half along MD direction, after the folding, the two hot melt faces are opposite, dimension TD76mm is MD100mm, wrap the sample with thin release film, heat seal is carried out in parallel at position 10mm away from the folding line, 3 samples (n is 3) with width of 15mm are cut at the middle position of the sample after heat seal, the cutting line is perpendicular to the heat seal line, the stretcher is opened, the distance of the chuck is set to be 50mm, the stretching speed is 300mm/min, the measuring stroke is 30mm, the air valve is opened, the air pressure is adjusted to be 0.6MPa-0.8MPa, the temperature is set according to the requirement, the sample strip is placed into the chuck vertically after the temperature is stable, two ends (single layer) of the sample strip are clamped, and the middle heat seal part faces inwards. And after the temperature reaches a set value, stabilizing for 2min, starting testing, and recording data. After the test, the heat seal should be pulled completely and the maximum value of the entire process is recorded. Note that M, MC, C, GC, and G are distinguished (M is the operator side, G is the driver side, and five points of equal width are sequentially selected). Closing the stretcher and the air valve, and cleaning the instrument and equipment.

MFR test method apparatus: Ray-Ran MFR300

The macromolecule (plastic) raw material to be detected is placed into a small groove, the tail end of the groove is connected with a thin tube, the diameter of the thin tube is 2.095mm, and the length of the thin tube is 8 mm. After heating to a certain temperature (350 ℃ of the fluorine resin), the upper end of the raw material is pressed downwards by a piston with a certain weight, and the weight of the raw material extruded within 10 minutes is measured to obtain the flow index of the plastic. The amount of thermoplastic mass extruded in a given time period, i.e.the mass of melt passing through a standard die capillary per 10min, expressed as MFR, is given in g/10min under the specified conditions.

Method for measuring insulation property after heat sealing

Equipment: chrysanthemum water TOS9200

Cutting a sample with the MD direction of 200mm and the TD direction of 76mm, folding the sample in half along the MD direction, adding a lug in the middle part, wherein the lug is made of Ni, and carrying out heat sealing on the lug. MD heat sealing, the heat sealing conditions are as follows: the heat sealing temperature is 190 ℃ (fixed), the heat sealing pressure is 1.0MPa, and the heat sealing time is 3 seconds. The vicinity of the heat-sealed portion of the tab was polished with sandpaper to expose AL, the negative electrode was brought into contact with the tab, the positive electrode was brought into contact with the exposed AL, and the resistance value under a voltage of 250V was measured. (one drop of pure water was dropped from the dropper to make the positive electrode better contact with AL at the site of polishing).

The test data are shown in table 1.

Table 1.

The analysis of the test data is carried out,

a small amount of polar molecules are attracted to the linear fluororesin chain, block copolymerization or random copolymerization is carried out to break the symmetry of the linear fluororesin chain, so that the MFR is improved, the MFR is improved from 10 to more than 20, the better the flow property of the material is realized more easily by heat sealing, and the good heat-sealing dissolution effect is realized.

In comparison with examples 1, 2, 3 and 4, in comparative example 1, the melting point of the maleic anhydride modified polypropylene resin is 135 ℃, the heat resistance is low, the battery can generate heat in the use and charge and discharge processes, if the heat resistance is low, the intermediate metal layer and the internal heat welding resin layer can be peeled off at high temperature, the heat sealing strength is 30N at 120 ℃, on one hand, the heat sealing part can be easily flawed and cracked by the gasification force of the heat sealing electrolyte at high temperature in the presence of the electrolyte, the electrolyte is contacted with the metal foil at a higher probability, and the insulation performance is reduced. In addition, the resin of the extruded part in the battery flows to the edge part which is not extruded by pressurization, the expansion and contraction of the battery, the external force of bending processing and the like cause cracks, the electrolyte can permeate to the middle metal layer through the cracks, the insulation resistance of the internally heat welded resin layer is reduced, the electric leakage phenomenon occurs, and the service life of the battery can be shortened; in the examples, after the fluorine-containing resin is modified by polar groups, the crystallinity of the polymer is obviously reduced, mainly because the introduced polar groups destroy the regularity of a main chain, the crystallinity of the polymer is obviously reduced, the MFR is increased, the fluidity is enhanced, the heat sealing effect is excellent, and the heat sealing strength is high. Comparative examples 1, 2, 3, 4, comparative example 4. The polypropylene is not modified, the melting point is 130 ℃, the heat resistance is low, the battery can generate heat in the using and charging and discharging processes, if the heat resistance is low, the intermediate metal layer and the internal heat welding resin layer can be peeled off at high temperature, the heat sealing strength is 30N at 120 ℃, and the heat sealing strength is low. Under the condition of electrifying in the use process of the battery, the insulation performance is lower, and once electrolyte contacts the aluminum foil to form a short circuit, serious unsafe results are caused.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The above matters related to the common general knowledge are not described in detail and can be understood by those skilled in the art.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A metal composite film, comprising: a metal level, an inlayer adhesive linkage, a hot melt resin layer, an outer adhesive linkage and an skin, its characterized in that, the skin sets up in metal level one side, the hot melt resin layer sets up in the metal level opposite side, the inlayer adhesive linkage set up in the metal level with between the first hot melt resin layer, outer adhesive linkage set up in between skin and the metal level, the hot melt resin layer is the fluorine-containing resin and inlays the layer structure of forging or random copolymerization polar group formation.

2. The metal composite film according to claim 1, wherein the fluorine-containing resin is any one or more of tetrafluoroethylene resin, vinylidene fluoride resin, and a copolymer of tetrafluoroethylene and ethylene, tetrafluoroethylene and perfluoroalkyl ether.

3. The metal composite film according to claim 1, wherein the polar group is any one or more of an acidic group, a halogen, an epoxy, an ether group.

4. The metal composite film according to claim 3, wherein the acidic group is any one or more of maleic anhydride, fumaric acid, and itaconic acid.

5. The metal composite film according to claim 3, wherein the ether group is any one or more of a polyvinyl methyl ether and a polyvinyl ethyl ether.

6. The metal composite film according to claim 1, wherein the fluorine-containing resin has an MFR value of 20 to 30g/10 min.

7. The metal composite film according to claim 1, wherein the metal layer is provided with an anti-corrosion layer on both sides.

8. The metal composite film according to claim 1, wherein the outer layer is one or more of a fluorine-based resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a urea resin, an epoxy resin, an acrylic resin, a polyamide resin, a polyimide resin, a polyamideimide resin, a polyurethane resin, and a phenol resin.

9. The metal composite film according to claim 1, wherein the outer adhesive layer is a two-component polyurethane adhesive formed by using polyester polyol and polyurethane-modified polyol as a diol main agent and aromatic or aliphatic isocyanate as a curing agent.

10. The metal composite film according to claim 1, wherein the inner layer adhesive layer is any one or more of the fluorine resin, propylene resin, and propylene-ethylene copolymer resin.

11. The metal composite film according to claim 10, wherein the inner adhesive layer has a layer structure modified with a modifying group.

12. The metal composite film according to claim 11, wherein the modifying group is one or more of a carboxyl group, an acid anhydride group, an acid halide group, an epoxy group, a hydroxyl group, an amino group, a mercapto group, a carbonate bond, an amide bond, a urethane bond, and a urea bond.