JP6733674B2 - Lithium-ion battery packaging material - Google Patents

Description

The present invention relates to a battery packaging material and a battery using the packaging material.

2. Description of the Related Art In recent years, as batteries used in mobile terminal devices such as personal computers and mobile phones, video cameras, satellites, etc., ultra-thin and miniaturized lithium batteries have been actively developed. The packaging material for this lithium battery is different from metal cans that have been used in the past, and has the advantage of being lightweight and allowing the shape of the battery to be freely selected. Therefore, a laminate having a structure such as a base material layer/barrier layer/sealant layer is used. Has come to be used.

A lithium battery is impregnated with an electrolyte solution obtained by dissolving a lithium salt in an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or the like together with a positive electrode material and a negative electrode material as battery contents. It contains an electrolyte layer made of a polymer gel. When such a strongly permeable solvent passes through the sealant layer, the lamination strength between the aluminum foil layer and the sealant layer is reduced to cause delamination, and finally the electrolyte solution leaks. Also, as the lithium salt that is the electrolyte of the battery, substances such as LiPF ₆ and LiBF ₄ are used, but these salts generate hydrofluoric acid due to the hydrolysis reaction with water, and hydrofluoric acid corrodes the aluminum foil. By doing so, the laminate strength is reduced. Thus, the battery packaging material needs to have resistance to the electrolyte.

Further, the lithium battery needs to have more severe durability in consideration of being used in various environments. For example, in the case of being used for a mobile device, liquid leakage resistance is required in a high temperature environment of 60 to 70° C. such as in a car. In addition, assuming that it was used in a mobile phone and accidentally dropped into water, water resistance is also required to prevent water from entering.

Under such circumstances, various packaging materials for lithium batteries having improved electrolytic solution resistance have been proposed (see, for example, Patent Documents 1 to 6).

JP 2001-243928 A JP, 2004-42477, A JP, 2004-142302, A JP, 2009-238475, A JP, 2010-086744, A Japanese Patent No. 5670803

However, the proposed packaging materials for lithium batteries are still insufficient in terms of electrolytic solution resistance. Further, even if the electrolytic solution resistance was greatly improved, there were problems.

Specifically, it is difficult for the adhesive layer to secure the pot life after blending the curing agent with the electrolytic solution resistance (Patent Document 1), and since the adhesive layer is an extruded resin, the laminating machine base is restricted. The heat-shrinking effect of the polyolefin base material is caused by the lamination in (Patent Documents 2, 3, 5), and the drying time is long and the production conditions are limited because the polyolefin main agent is water-based (Patent Documents 4, 6). Problems such as, were seen.

An object of the present invention is to provide a packaging material for a battery, which is excellent in electrolytic solution resistance, and a battery using the packaging material, without problems such as restrictions on pot life and production conditions.

In order to achieve the above-mentioned subject, the present inventors have conducted extensive studies and have proposed the following invention.

A battery packaging material comprising a barrier layer, an adhesive layer, and a sealant layer laminated in this order, wherein the adhesive layer has an acid value of 5 to 50 mgKOH/g-resin, an acid-modified polyolefin (A), a glycidyl amine type. A packaging material for a battery, which comprises a reaction product of an epoxy resin (B1) and a glycidyl ether type epoxy resin (B2).

The glycidylamine type epoxy resin (B1) is preferably an epoxy resin having two or more glycidyl groups in one molecule.

The glycidyl amine type epoxy resin (B1) is preferably a compound represented by the general formula (1).

(In general formula (1), R is an aryl group which may have a substituent, A1 and A2 are each independently an alkylene group which may have a substituent having 1 to 5 carbon atoms, (m is 1 or 2 and n is 1 or 2.)
The glycidyl ether type epoxy resin (B2) is preferably an epoxy resin having two or more glycidyl groups in one molecule and containing no nitrogen atom.

The adhesive layer comprises 0.01 to 20 parts by mass of the glycidyl amine type epoxy resin (B1) and 1 to 20 parts by mass of the glycidyl ether type epoxy resin (B2) with respect to 100 parts by mass of the acid-modified polyolefin (A). It is preferable to contain a reactant.

A solution containing an acid-modified polyolefin (A), a glycidyl amine type epoxy resin (B1), a glycidyl ether type epoxy resin (B2) and an organic solvent (C) is applied to the surface of the barrier layer and dried to form an adhesive layer. Then, the method for producing a battery packaging material according to any one of the above, wherein a sealant layer is laminated on the surface of the adhesive layer.

A battery using the battery packaging material according to any one of the above.

The organic solvent (C) is a mixed liquid of the solvent (C1) and the solvent (C2), and the solvent (C1) is selected from aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons and halogenated hydrocarbons. The solvent (C2) is one or more solvents selected from the group consisting of, and the solvent (C2) is one or more solvents selected from the group consisting of alcohol solvents, ketone solvents, ester solvents, and glycol ether solvents. And it is preferable that solvent (C1)/solvent (C2)=50 to 97/50 to 3 (mass ratio).

The battery packaging material of the present invention is a battery packaging material in which a barrier layer, an adhesive layer and a sealant layer are sequentially laminated, and a composition comprising a specific resin and a specific crosslinking agent is used for the adhesive layer. Therefore, when it is used as a battery packaging material, it exhibits excellent electrolytic solution resistance, and as a result, the battery life is extended, handling safety is enhanced, and its industrial utility value is extremely high.

In addition, the production method according to the present invention is preferable in that it is easy to adjust the basis weight of the adhesive layer, the thickness is easily controlled, and the solvent system is used, so that the drying conditions are not limited and the packaging material can be efficiently produced. ..

Hereinafter, embodiments of the present invention will be described in detail.

<< adhesive layer >>
The adhesive layer needs to contain a reaction product of an acid-modified polyolefin (A) having an acid value of 5 to 50 mgKOH/g-resin, a glycidylamine type epoxy resin (B1) and a glycidyl ether type epoxy resin (B2). is there. The adhesive layer is not particularly limited, but an adhesive composition containing an acid-modified polyolefin (A), a glycidyl amine type epoxy resin (B1), a glycidyl ether type epoxy resin (B2) and an organic solvent (C) is used as a barrier layer. It is preferably a layer of an adhesive composition obtained by coating and drying the surface to remove the organic solvent (C) and then aging (curing reaction).

The thickness of the adhesive layer is not particularly limited, but is preferably 1 μm or more, more preferably 2 μm or more, further preferably 3 μm or more, preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less. When the thickness is less than the above range, the adhesiveness may not be exhibited, and when the thickness exceeds the above range, the workability may be deteriorated, and in addition, the efficiency is decreased in terms of manufacturing cost.

<Acid-modified polyolefin (A)>
The acid-modified polyolefin (A) used in the present invention is not limited, but at least one of polyethylene, polypropylene and a propylene-α-olefin copolymer may be at least an α,β-unsaturated carboxylic acid and its acid anhydride. Those obtained by grafting one kind are preferred.

The propylene-α-olefin copolymer is mainly propylene and is copolymerized with α-olefin. As the α-olefin, for example, ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate or the like can be used alone or in combination. Among these α-olefins, ethylene and 1-butene are preferable. The ratio of the propylene component and the α-olefin component of the propylene-α-olefin copolymer is not limited, but the propylene component is preferably 50 mol% or more, more preferably 70 mol% or more.

Examples of the α,β-unsaturated carboxylic acid and at least one of the acid anhydrides thereof include maleic acid, itaconic acid, citraconic acid, and acid anhydrides thereof. Among these, acid anhydrides are preferable, and maleic anhydride is more preferable. Specific examples include maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified propylene-ethylene-butene copolymer, and the like. These acid-modified polyolefins can be used alone or in combination of two or more.

The acid value of the acid-modified polyolefin (A) is required to have a lower limit of 5 mgKOH/g-resin or more, preferably 10 mgKOH/g-resin or more, from the viewpoint of pot life and adhesion between the barrier layer and the sealant layer. And more preferably 14 mgKOH/g-resin or more, further preferably 16 mgKOH/g-resin or more, particularly preferably 18 mgKOH/g-resin or more, and most preferably 20 mgKOH/g-resin or more. .. If it is less than the above value, the compatibility with the epoxy resin is low, the adhesive strength may not be exhibited, the crosslink density is low, and the chemical resistance may be poor. The upper limit must be 50 mgKOH/g-resin or less, preferably 48 mgKOH/g-resin or less, more preferably 46 mgKOH/g-resin or less, still more preferably 44 mgKOH/g-resin or less, and especially It is preferably 42 mgKOH/g-resin or less, and most preferably 40 mgKOH/g-resin or less. When it exceeds the above-mentioned value, the viscosity and stability of the solution may be lowered, and the pot life may be lowered. Further, the production efficiency is also lowered, which is not preferable.

The weight average molecular weight (Mw) of the acid-modified polyolefin (A) is preferably in the range of 40,000 to 180,000. The range is more preferably 50,000 to 160,000, further preferably 60,000 to 150,000, particularly preferably 70,000 to 140,000, and most preferably 80. It is in the range of 1,000 to 130,000. If it is less than the above value, the cohesive force becomes weak and the adhesiveness may be poor. On the other hand, when it exceeds the above-mentioned value, the fluidity is low, and there may be a problem in operability at the time of bonding. Within the above range, the curing reaction with the epoxy resin is utilized, which is preferable.

The acid-modified polypropylene (A) is preferably a crystalline acid-modified polypropylene (A). The crystalline acid-modified polyolefin (A) referred to in the present invention means that the temperature is raised from −100° C. to 250° C. at 20° C./min using a differential scanning calorimeter (DSC), and the temperature rising process is clear. Refers to those exhibiting melting peaks.

By making the acid-modified polyolefin crystalline, it is advantageous because it has stronger cohesive force than amorphous and has excellent adhesiveness and chemical resistance.

The melting point (Tm) of the acid-modified polyolefin (A) is preferably in the range of 50°C to 120°C. The range is more preferably 60°C to 100°C, and most preferably 70°C to 90°C. If it is less than the above value, the cohesive force derived from crystals becomes weak, and the adhesiveness and chemical resistance may be poor. On the other hand, when it exceeds the above-mentioned values, solution stability and fluidity are low, and there may be a problem in operability in bonding.

The heat of fusion (ΔH) of the acid-modified polyolefin (A) is preferably in the range of 5 J/g to 60 J/g. The range is more preferably 10 J/g to 50 J/g, and most preferably 20 J/g to 40 J/g. If it is less than the above value, the cohesive force derived from crystals becomes weak, and the adhesiveness and chemical resistance may be poor. On the other hand, when it exceeds the above-mentioned values, solution stability and fluidity are low, and there may be a problem in operability in bonding.

The method for producing the acid-modified polyolefin (A) is not particularly limited, and examples thereof include a radical graft reaction (that is, a radical species is generated with respect to a polymer serving as a main chain, and the radical species is used as a polymerization initiation point to obtain an unsaturated carboxylic acid and A reaction of graft-polymerizing an acid anhydride, and the like.

The radical generator is not particularly limited, but it is preferable to use an organic peroxide. The organic peroxide is not particularly limited, but includes di-tert-butylperoxyphthalate, tert-butylhydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy-. Peroxides such as 2-ethylhexanoate, tert-butylperoxypivalate, methylethylketone peroxide, di-tert-butylperoxide, lauroyl peroxide; azobisisobutyronitrile, azobisisopropionitrile, etc. Examples include azonitriles

<Glycidylamine type epoxy resin (B1)>
The glycidyl amine type epoxy resin (B1) used in the present invention is not particularly limited as long as it is an epoxy resin having one glycidyl group in one molecule. It is preferable to have two or more glycidyl groups in one molecule of the epoxy resin, more preferable to have three or more glycidyl groups in one molecule of the epoxy resin, and to have four or more glycidyl groups in one molecule of the epoxy resin. It is more preferable to have.

Further, the glycidyl amine type epoxy resin (B1) is preferable because the chemical resistance is further improved by using the compound represented by the following general formula (1).

In general formula (1), R is an aryl group which may have a substituent, preferably a phenyl group which may have a substituent. The substituent of the aryl group is not particularly limited, but an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxyl group, an amino group, a glycidyl group, a glycidylamino group, a glycidyl ether group can be used. Can be mentioned. A1 and A2 are each independently a linear alkylene group which may have a substituent having 1 to 5 carbon atoms, and preferably has 4 or less carbon atoms, more preferably 3 or less, and further preferably Is 2 or less. The substituent of the alkylene group is not particularly limited, and examples thereof include an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an amino group. m is 1 or 2, and n is 1 or 2. Preferably, either m or n is 2, and more preferably both m and n are 2.

Specific examples of the glycidyl amine type epoxy resin (B1) are not particularly limited, but tetraglycidyl diaminodiphenylmethane, triglycidyl paraaminophenol, tetraglycidyl bisaminomethylcyclohexanone, N,N,N′,N′-tetraglycidyl-m. -Glycidyl amines such as xylene diamine and the like can be mentioned. Among them, N,N,N',N'-tetraglycidyl-m-xylenediamine is preferable. These glycidyl amine type epoxy resins (B1) can be used alone or in combination of two or more kinds.

The blending amount of the glycidyl amine type epoxy resin (B1) is preferably 0.01 parts by mass or more, and more preferably 0.05 parts by mass or more with respect to 100 parts by mass of the acid-modified polyolefin (A). , 0.1 part by mass or more, particularly preferably 1 part by mass or more, and most preferably 2 parts by mass or more. Further, it is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, further preferably 16 parts by mass or less, particularly preferably 14 parts by mass or less, and 12 parts by mass or less. Most preferably. If it is less than the above range, the catalytic action may not be exhibited, and the adhesiveness and chemical resistance in bonding and aging at 80° C. or lower may be low. If it exceeds the above range, the crosslinking reaction proceeds excessively, the rigidity becomes high, and the adhesiveness tends to decrease. In addition, the crosslinking reaction is likely to proceed during storage of the adhesive composition solution, and the pot life tends to be reduced.

<Glycidyl ether type epoxy resin (B2)>
The glycidyl ether type epoxy resin (B2) used in the present invention is not particularly limited as long as it is an epoxy resin having a glycidyl ether group in the molecule. The epoxy resin preferably has two or more glycidyl groups in one molecule of the epoxy resin, and more preferably the epoxy resin having two or more glycidyl groups in one molecule of the epoxy resin and containing no nitrogen atom. ..

The blending amount of the glycidyl ether type epoxy resin (B2) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and 3 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin (A). More preferably, it is more preferably 4 parts by mass or more, particularly preferably 5 parts by mass or more. Further, it is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, further preferably 16 parts by mass or less, particularly preferably 14 parts by mass or less, and 12 parts by mass or less. Most preferably. Within the above range, excellent adhesiveness and chemical resistance can be exhibited.

Specific examples of the glycidyl ether type epoxy resin (B2) include, but are not limited to, a phenol novolac type epoxy resin and a cresol novolac type epoxy resin, which are used from the viewpoint of adhesiveness with a barrier layer and chemical resistance. preferable. These glycidyl ether type epoxy resins (B2) can be used alone or in combination of two or more kinds.

The present invention is characterized in that two kinds of epoxy resins, the glycidyl amine type epoxy resin (B1) and the glycidyl ether type epoxy resin (B2), are used in combination as essential components. By using the glycidyl amine type epoxy resin (B1) and the glycidyl ether type epoxy resin (B2) together, excellent adhesiveness and chemical resistance can be exhibited. That is, the glycidyl amine type epoxy resin (B1) has a reaction and curing action between the acid-modified polyolefin (A) and the glycidyl ether type epoxy resin (B2). Furthermore, the glycidyl amine type epoxy resin (B1) includes acid-modified polyolefin (A) and glycidyl amine type epoxy resin (B1), glycidyl amine type epoxy resins (B1), glycidyl ether type epoxy resins (B2), and glycidyl amine. The epoxy resin (B1) and the glycidyl ether epoxy resin (B2) have a reaction and curing catalytic action. Therefore, by blending them, adhesion at 80° C. or lower, adhesion with a barrier layer and chemical resistance in aging. The property can be improved.

The total blending amount of the glycidyl amine type epoxy resin (B1) and the glycidyl ether type epoxy resin (B2) is preferably 2 to 40 parts by mass, and 5 to 100 parts by mass of the acid-modified polyolefin (A). It is more preferably 20 parts by mass, and most preferably 10 to 16 parts by mass. If it is less than the above range, a sufficient curing effect may not be obtained and the adhesiveness and chemical resistance may be low, and if it exceeds the above range, it is not preferable from the viewpoints of pot life and adhesiveness between the sealant layer and cost.

The content of the glycidyl amine type epoxy resin (B1) is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and most preferably 3 to 10% by mass based on the whole epoxy resin. .. If the blending amount is less than the above, the catalytic action is not expressed, low-temperature bonding, the adhesiveness and chemical resistance in aging may be low, and if it exceeds the above, the crosslinking reaction proceeds excessively and the rigidity becomes high. , The adhesiveness tends to decrease. In addition, the crosslinking reaction is likely to proceed during storage of the adhesive composition solution, and the pot life tends to be reduced.

Other epoxy resins can be used together as the epoxy resin used in the present invention. For example, glycidyl ester type such as hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester, triglycidyl isocyanurate, or 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, epoxidized soybean oil or the like alicyclic or fat Group epoxides and the like can be used, and they may be used alone or in combination of two or more.

<Organic solvent (C)>
The organic solvent (C) used in the present invention is not particularly limited as long as it can dissolve the acid-modified polyolefin (A), the glycidyl amine type epoxy resin (B1) and the glycidyl ether type epoxy resin (B2). Specifically, for example, aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane, heptane, octane and decane, cycloaliphatic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane and ethylcyclohexane. Hydrogen, halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene and chloroform, alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol and phenol, acetone, methyl isobutyl ketone, Methyl ethyl ketone pentanone, hexanone, cyclohexanone, isophorone, ketone solvent such as acetophenone, methyl cellosolve, cellosolve such as ethyl cellosolve, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ester solvent such as butyl formate, Ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, tetraethylene glycol A glycol ether solvent such as mono-n-butyl ether may be used, and one or more of these may be used in combination.

The organic solvent (C) is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and further preferably 100 parts by mass or more with respect to 100 parts by mass of the acid-modified polyolefin (A). It is particularly preferably 110 parts by mass or more. Further, it is preferably 1000 parts by mass or less, more preferably 900 parts by mass or less, further preferably 800 parts by mass or less, and particularly preferably 700 parts by mass or less. If it is less than the above range, the liquid property and pot life may be deteriorated, and if it exceeds the above range, it may be disadvantageous in terms of manufacturing cost and transportation cost.

The organic solvent (C) is one selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons and halogenated hydrocarbons, from the viewpoint of liquid property and pot life of the adhesive composition. A mixed solution of at least one solvent (C2) selected from the group consisting of the above solvent (C1), alcohol solvent, ketone solvent, ester solvent and glycol ether solvent is preferable. The mixing ratio is preferably solvent (C1)/solvent (C2)=50 to 97/50 to 3 (mass ratio), more preferably 55 to 95/45 to 5 (mass ratio), It is more preferably 60 to 90/40 to 10 (mass ratio), and particularly preferably 70 to 80/30 to 20 (mass ratio). If the amount is out of the above range, the liquid property and pot life of the adhesive composition may deteriorate. Further, it is particularly preferable that the solvent (C1) is an aromatic hydrocarbon or an alicyclic hydrocarbon and the solvent (C2) is a ketone solvent.

<Adhesive composition>
The adhesive composition according to the present invention is a mixture of the acid-modified polyolefin (A), the glycidyl amine type epoxy resin (B1), the glycidyl ether type epoxy resin (B2) and the organic solvent (C). The acid-modified polyolefin (A), the glycidyl amine type epoxy resin (B1) and the glycidyl ether type epoxy resin (B2) may be dissolved or dispersed in the organic solvent (C). It is preferably dissolved from the viewpoint of pot life.

The adhesive composition contains various types of acid-modified polyolefin (A), glycidyl amine type epoxy resin (B1), glycidyl ether type epoxy resin (B2) and organic solvent (C), as long as the performance of the present invention is not impaired. It is possible to mix and use the additive of. The additives are not particularly limited, but it is preferable to use flame retardants, pigments, antiblocking agents and the like.

<< Sealant layer >>
The sealant layer used in the present invention is not particularly limited, but it is preferable to use polyolefin from the viewpoint of liquid leakage resistance and heat resistance. The polyolefin may be appropriately selected from conventionally known polyolefin resins. For example, polyethylene, polypropylene, ethylene-propylene copolymer and the like can be used, although not particularly limited thereto. Of these, polypropylene is preferably used, and polypropylene may be appropriately selected from random propylene, homopropylene, and block propylene.

The sealant layer in the present invention may be multilayered by appropriately combining the above-mentioned types of polypropylene layers. The thickness is not particularly limited, but is preferably 20 to 100 μm, more preferably 25 to 95 μm, and further preferably 30 to 90 μm. The polyolefin resin substrate may be mixed with pigments and various additives as needed.

<< barrier layer >>
The barrier layer used in the present invention is a layer having a barrier property of preventing oxygen and moisture from entering the inside of the lithium ion battery. Although not particularly limited, a metal foil such as pure aluminum, an aluminum-iron alloy, copper, nickel, and stainless steel, or a vapor deposition film of aluminum, nickel, silica, alumina, or the like is preferable. From the viewpoint of barrier properties, it is preferable to use an aluminum foil. Further, in order to improve corrosion resistance and adhesion, it is preferable that the barrier layer is subjected to surface treatment such as chromate treatment. Specifically, chromate chromate treatment, phosphoric acid chromate treatment, coating chromate treatment And the like, or non-chromium (coating type) chemical conversion treatment using zirconium, titanium, zinc phosphate or the like. These treatments may be performed alone, or may be appropriately used in combination with an organic binder component.

When an aluminum foil is used, a soft aluminum foil having a thickness of 9 to 200 μm, particularly a soft aluminum foil having an iron content of 0.1 to 9.0 mass% is a pinhole-resistant material and has good spreadability during molding. Is preferred. If the iron content is less than 0.1% by mass, sufficient pinhole resistance and spreadability cannot be imparted, and if it exceeds 9.0% by mass, the flexibility may be impaired.

When a soft aluminum foil is used, it is preferable to perform a known surface treatment on the surface on which the adhesive layer is laminated in order to improve the corrosion resistance and the adhesiveness with the adhesive layer.

<< Battery Packing Material >>
As described above, the battery packaging material of the present invention has the barrier layer, the adhesive layer, and the sealant layer laminated in this order.

Next, an example of a method for producing the battery packaging material of the present invention will be described.

In the present invention, first, an adhesive layer is provided on the surface of the barrier layer. In the present invention, the method for providing the adhesive layer is not particularly limited, but contains the acid-modified polypropylene resin (A), the glycidyl amine type epoxy resin (B1), the glycidyl ether type epoxy resin (B2) and the organic solvent (C). A method of applying the adhesive composition to the surface of the barrier layer, drying and removing the organic solvent (C), and then performing a curing reaction can be mentioned. In addition, a method may be mentioned in which the adhesive composition is applied on a release paper, the organic solvent (C) is dried and a curing reaction is performed to once release the adhesive layer, and then the adhesive layer is transferred to the barrier layer or the sealant layer. Among them, the former method is preferable from the viewpoint of performance, since the thickness of the adhesive layer can be freely controlled, and among them, the method of applying the adhesive composition to the surface of the barrier layer is preferable in practice.

As a method for applying the adhesive composition, a known method, for example, gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, brush coating, etc., Form a uniform adhesive layer by applying a uniform coating on the surface of the barrier layer or sealant layer, setting it at around room temperature as necessary, and then subjecting it to a drying treatment or a heating treatment for drying to bring the uniform adhesive layer into close contact with the coated surface. can do.

After providing the adhesive layer, a sealant layer is provided. The method of providing the sealant layer is not particularly limited, but a method of bonding the sealant film made of the above-mentioned sealant resin and the adhesive layer by heat (thermal lamination, dry lamination) or extruding the melted resin and attaching it A method of combining (extrusion lamination) and the like can be mentioned.

The battery packaging material of the present invention can be produced by the method described above. According to such a method, the thickness of the adhesive layer can be easily adjusted, so that the packaging material can be efficiently produced.

The battery packaging material of the present invention has a structure in which a barrier layer, an adhesive layer, and a sealant layer are laminated in this order in the thickness direction, and further provided with a base layer made of a single-layer or multilayer heat-resistant polymer film. May be.

As the base material layer, for example, a single film such as a stretched or unstretched film such as a polyester film, a polyamide film, or a polypropylene film, or a multilayer film in which the single film is laminated can be used.

A primer layer may be provided between the base material layer and the barrier layer, if necessary. For the primer layer, a polyurethane adhesive containing silane coupling agent, polyester polyol, polyether polyol, or acrylic polyol as a main component can be used.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples. In the examples and the comparative examples, "parts" means "parts by mass".

Production example 1
In a 1 L autoclave, 100 parts by mass of a propylene-butene copolymer ("Tufmer (registered trademark) XM7080" manufactured by Mitsui Chemicals, Inc.), 150 parts by mass of toluene, 25 parts by mass of maleic anhydride, 6 parts by mass of di-tert-butyl peroxide. Was added, the temperature was raised to 140° C., and the mixture was further stirred for 3 hours. Then, after cooling the obtained reaction liquid, it was poured into a container containing a large amount of methyl ethyl ketone to precipitate a resin. Then, by centrifuging the liquid containing the resin, the acid-modified propylene-butene copolymer graft-polymerized with maleic anhydride, the (poly)maleic anhydride and the low molecular weight substance were separated and purified. Then, by drying at 70° C. under reduced pressure for 5 hours, a maleic anhydride-modified propylene-butene copolymer (PO-1, acid value 48 mg KOH/g-resin, weight average molecular weight 50,000, Tm 75° C., ΔH 25 J/ g) was obtained.

Production example 2
A maleic anhydride-modified propylene-butene copolymer (PO-2, acid value 25 mgKOH/g-resin, weight average) was obtained in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 20 parts by mass. A molecular weight of 80,000, Tm of 75° C., ΔH of 30 J/g) was obtained.

Production Example 3
A maleic anhydride-modified propylene-butene copolymer (was prepared in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 3 parts by mass and the amount of di-tert-butyl peroxide was changed to 0.5 part by mass. PO-3, acid value 5 mg KOH/g-resin, weight average molecular weight 180,000, Tm 80° C., ΔH 25 J/g) were obtained.

Production Example 4
A maleic anhydride-modified propylene-butene copolymer (PO-4, acid value 55 mgKOH/g-resin, weight average) was obtained in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 30 parts by mass. A molecular weight of 40,000, Tm of 70° C., ΔH of 25 J/g) was obtained.

Production Example 5
A maleic anhydride-modified propylene-butene copolymer (() was prepared in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 2 parts by mass and the amount of di-tert-butyl peroxide was changed to 0.5 part by mass. PO-5, acid value 3 mg KOH/g-resin, weight average molecular weight 200,000, Tm 80° C., ΔH 25 J/g) were obtained.

(Preparation of main agent 1)
In a 500 ml four-necked flask equipped with a water-cooled reflux condenser and a stirrer, 100 parts by mass of the maleic anhydride-modified propylene-butene copolymer (PO-1) obtained in Production Example 1 and 280 parts by mass of methylcyclohexane. Parts and 120 parts by mass of methyl ethyl ketone were charged, the temperature was raised to 80° C. with stirring, and the stirring was continued for 1 hour to obtain a main agent 1. The solution state is shown in Table 1.

(Preparation of main ingredients 2 to 12)
The acid-modified polyolefin and the organic solvent were changed as shown in Table 1, and main ingredients 2 to 12 were produced in the same manner as the main ingredient 1. Table 1 shows the blending amount and the solution state.

Example 1
500 parts by mass of the main agent 1, 19.8 parts by mass of a phenol novolac type epoxy resin which is a glycidyl ether type epoxy resin (B2) as a curing agent, and TETRAD (registered trademark)-X which is a glycidyl amine type epoxy resin (B1). 0.2 parts by mass was blended to obtain an adhesive composition. Table 2 shows the evaluation results of pot life, adhesiveness and chemical resistance.

Examples 2-15, Comparative Examples 1-6
Main ingredients 1 to 12 and each curing agent were changed as shown in Tables 2 and 3, and Examples 2 to 15 and Comparative Examples 1 to 6 were carried out in the same manner as in Example 1. The blending amount, pot life property, adhesive property and chemical resistance are shown in Tables 2 and 3.

The curing agents used in Tables 2 and 3 are as follows.
<Glycidylamine type epoxy resin (B1)>
N,N,N',N'-tetraglycidyl-m-xylenediamine: TETRAD (registered trademark)-X (manufactured by Mitsubishi Gas Chemical Co., Inc.)
<Glycidyl ether type epoxy resin (B2)>
Phenol novolac type epoxy resin: jER (registered trademark) 152 (manufactured by Mitsubishi Chemical Corporation)
o-Cresol novolac type epoxy resin: YDCN-700-3 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)
<Other curing agents>
Polyisocyanate: Duranate (registered trademark) TPA-100 (manufactured by Asahi Kasei Corp.)
Silane coupling agent: KBM-403 (manufactured by Shin-Etsu Silicone Co., Ltd.)

The acid-modified polyolefin, the main agent and the adhesive composition obtained as described above were subjected to analytical measurement and evaluation based on the following methods.

Measurement of Acid Value The acid value (mgKOH/g-resin) in the present invention was prepared using FT-IR (manufactured by Shimadzu Corporation, FT-IR8200PC) with a chloroform solution of maleic anhydride (manufactured by Tokyo Kasei). Calculated by the following formula using the coefficient (f) obtained from the calibration curve and the absorbance (I) of the stretching peak (1780 cm ⁻¹ ) of the carbonyl (C═O) bond of maleic anhydride in the crystalline maleic anhydride-modified polyolefin solution. It is the value.
Acid value (mgKOH/g-resin)=[absorbance (I)×(f)×2×potassium hydroxide molecular weight×1000 (mg)/maleic anhydride molecular weight]
Molecular weight of maleic anhydride: 98.06 Molecular weight of potassium hydroxide: 56.11

Measurement of weight average molecular weight (Mw) The weight average molecular weight in the present invention is the gel permeation chromatograph Alliance e2695 (hereinafter, GPC, standard substance: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-806 + KF ) manufactured by Japan Waters Corporation. -803, column temperature: 40°C, flow rate: 1.0 ml/min, detector: photodiode array detector (wavelength 254 nm = ultraviolet ray)).

Measurement of melting point and heat of fusion The melting point and heat of fusion in the present invention were measured at a rate of 20°C/min using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instrument Japan, Q-2000). It is a value measured from the top temperature and the area of the melting peak when the resin is warm-melted, cooled into a resin, and again heated and melted.

Evaluation of solution state of base material The solution state of base materials 1 to 12 was evaluated by measuring the solution viscosity at 25° C. using a Brookfield viscometer TVB-10M (hereinafter referred to as B type viscometer) manufactured by Toki Sangyo Co., Ltd. did.
<Evaluation criteria>
◯ (excellent in practical use): less than 500 mPa·s Δ (practical): 500 mPa·s or more and less than 1000 mPa·s × (impractical): 1000 mPa·s or more or viscosity measurement not possible due to gelation

Evaluation of pot-life property The pot-life property refers to the stability of the solution immediately after compounding the acid-modified polyolefin with a crosslinking agent or a curing agent or after a certain period of time after compounding. If the pot life is good, it means that the viscosity of the solution does not rise so much that it can be stored for a long time. If the pot life is bad, the viscosity of the solution increases (thickens), and if it is severe, A gelation phenomenon occurs, making it difficult to apply to a substrate, and it means that it cannot be stored for a long time. The pot life properties of the adhesive compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 6 were stored at 25° C. and 40° C. for 24 hours, and then the solution viscosity at 25° C. was measured using a B-type viscometer. Was evaluated by measuring.
<Evaluation criteria>
◯ (excellent in practical use): less than 500 mPa·s Δ (practical): 500 mPa·s or more and less than 1000 mPa·s × (impractical): 1000 mPa·s or more or viscosity measurement not possible due to gelation

Preparation of packaging material for lithium-ion battery Aluminum foil (8079-0 material manufactured by UACJ, thickness 40 μm) is used for the barrier layer, and unstretched polypropylene film (Pyrene (registered trademark) film CT manufactured by Toyobo Co., Ltd., thickness is used for the sealant. 40 μm) (hereinafter, also referred to as CPP). The adhesive compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 6 were applied to the surface of the barrier layer using a bar coater so that the thickness of the adhesive layer after drying was adjusted to 3 μm. Then, it was dried in a 100° C. atmosphere for 1 minute using a warm air dryer to obtain an adhesive layer having a film thickness of 3 μm. A sealant layer is overlaid on the surface of the adhesive layer, and a small tabletop test laminator (SA-1010-S) manufactured by Tester Sangyo Co., Ltd. is used for bonding at 80°C, 0.3 MPa, 1 m/min, 40°C, 50% A packaging material for a lithium ion battery was obtained by aging (aging) for 120 hours at RH.

The lithium ion battery packaging material obtained as described above was evaluated by the following methods.

Evaluation of Adhesiveness The battery packaging material was cut into a size of 100 mm×15 mm, and the adhesiveness was evaluated by a T-type peel test. The evaluation results are shown in Tables 2 and 3.

<T-type peel test>
According to the test method of ASTM-D1876-61, the peel strength at a tensile speed of 50 mm/min was measured under a 25° C. environment using Tensilon RTM-100 manufactured by Orientec Corporation. The peel strength (N/cm) between the barrier layer (aluminum foil)/sealant layer (CPP) was the average value of the test values of 5 times.

<Evaluation criteria>
☆ (especially excellent in practical use): 8.0 N/cm or more or CPP breaks down (hereinafter also simply referred to as “breaking down.”) Breakage means that peeling does not occur at the aluminum foil/CPP interface, and aluminum It means that the foil or CPP is destroyed.
◎ (excellent in practical use): 7.5 N/cm or more and less than 8.0 N/cm ○ (practical use): 7.0 N/cm or more and less than 7.5 N/cm × (impractical): less than 7.0 N/cm

Evaluation of Electrolytic Solution Resistance The battery packaging material was cut into a size of 100 mm×15 mm, and the electrolytic solution [ethylene carbonate/diethyl carbonate/dimethyl carbonate=1/1/1 (volume ratio) was used for lithium hexafluorophosphate. Was added for 3 days at 85°C. Then, the laminate was taken out, washed with ion-exchanged water, wiped off with water with a paper wiper, and the electrolytic solution resistance was evaluated by a T-type peeling test.

<Evaluation criteria>
☆ (especially excellent in practical use): 8.0 N/cm or more or material break ◎ (excellent in practical use): 7.5 N/cm or more and less than 8.0 N/cm ○ (practical): 7.0 N/cm or more 7. Less than 5 N/cm x (impractical): less than 7.0 N/cm

The battery packaging material of the present invention is a battery packaging material in which a barrier layer, an adhesive layer and a sealant layer are sequentially laminated, and a composition comprising a specific resin and a specific crosslinking agent is used for the adhesive layer. Therefore, when used as a packaging material for batteries, it exhibits excellent electrolytic solution resistance, resulting in a longer battery life and improved handling safety, and is used in lithium batteries used in personal computers, mobile phones, video cameras, etc. It can be widely used as a battery packaging material (pouch type).

Claims (8)

A battery packaging material comprising a barrier layer, an adhesive layer, and a sealant layer laminated in this order, wherein the adhesive layer has an acid value of 5 to 50 mgKOH/g-resin, an acid-modified polyolefin (A), a glycidyl amine type. A packaging material for a battery, which comprises a reaction product of an epoxy resin (B1) and a glycidyl ether type epoxy resin (B2). The packaging material for a battery according to claim 1, wherein the glycidyl amine type epoxy resin (B1) is an epoxy resin having two or more glycidyl groups in one molecule. The battery wrapping material according to claim 1 or 2, wherein the glycidyl amine type epoxy resin (B1) is a compound represented by the general formula (1).

(In general formula (1), R is an aryl group which may have a substituent, A1 and A2 are each independently an alkylene group having 1 to 5 carbon atoms which may have a substituent, (m is 1 or 2 and n is 1 or 2.) The packaging material for a battery according to claim 1, wherein the glycidyl ether type epoxy resin (B2) is an epoxy resin having two or more glycidyl groups in one molecule and containing no nitrogen atom. .. The adhesive layer contains 0.01 to 20 parts by mass of the glycidyl amine type epoxy resin (B1) and 1 to 20 parts by mass of the glycidyl ether type epoxy resin (B2) with respect to 100 parts by mass of the acid-modified polyolefin (A). The packaging material for a battery according to claim 1, which contains a reactant. A battery using the battery packaging material according to claim 1. An adhesive composition containing an acid-modified polyolefin (A), a glycidyl amine type epoxy resin (B1), a glycidyl ether type epoxy resin (B2) and an organic solvent (C) is applied to the surface of the barrier layer and dried to adhere. The method for producing a battery packaging material according to claim 1, wherein a layer is formed and then a sealant layer is laminated on the surface of the adhesive layer. The organic solvent (C) is a mixed liquid of the solvent (C1) and the solvent (C2), and the solvent (C1) is selected from aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons and halogenated hydrocarbons. The solvent (C2) is one or more solvents selected from the group consisting of, and the solvent (C2) is one or more solvents selected from the group consisting of alcohol solvents, ketone solvents, ester solvents, and glycol ether solvents. And the solvent (C1)/solvent (C2)=50 to 97/50 to 3 (mass ratio), The method for producing a battery packaging material according to claim 7.