JP5954283B2 - Adhesive composition for laminate laminate, laminate using the same, and secondary battery - Google Patents

Description

  In particular, the present invention relates to an adhesive composition for a laminate laminate suitable for sealing an electrolyte used in a secondary battery, a laminate using the same, and a secondary battery.

A secondary battery typified by a lithium ion battery has a configuration in which a positive electrode, a negative electrode, and an electrolytic solution or the like are enclosed therebetween. In addition, as an encapsulating bag for enclosing a lead wire for taking out electricity from the positive electrode and the negative electrode, a laminated body in which a metal foil such as an aluminum foil or a metal vapor deposition layer and a plastic are bonded together is used.
This laminate requires moisture resistance, sealing, puncture resistance, insulation, heat / cold resistance, corrosion resistance, etc. required for secondary batteries, but in particular, electrolyte resistance that does not dissolve in the electrolyte is essential. It is.
For example, a secondary battery electrode comprising a modified polyolefin resin (A) and a polyurethane resin (B), wherein (B) is 0.5 to 100 parts by mass relative to 100 parts by mass of (A) A resin composition for binders has been proposed (see, for example, Patent Document 1). However, only the polyolefin resin containing an acid group is excellent in adhesion to the olefin sheet due to processes such as high temperature aging and extrusion lamination, but the adhesion to the metal layer is insufficient. As a result, the adhesive strength as an adhesive for laminates is insufficient. Further, when used in a secondary battery, the electrolyte resistance is also insufficient, and there has been a difficulty in causing delamination over time.

JP 2010-277959 A

  The object of the present invention is excellent in adhesion between the metal layer and the plastic layer, satisfying moisture proofing, heat resistance, insulation, durability, etc., and also having electrolyte resistance, and may cause delamination over time. There is no adhesive composition for laminate laminates, a laminate using the same, and a secondary battery.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a composition containing a hydroxyl group-containing polyolefin resin and an acid group-containing polyolefin, a specific epoxy compound, and a polyisocyanate compound is bonded to a laminate laminate by dry lamination. As a preparation, the inventors found that the present invention has a remarkable effect and completed the invention.

Specifically, the present invention, hydroxyl group-containing polyolefin resin and acid group-containing polyolefin resin (A), the alcohol-based epoxy compound (B), and a polyfunctional isocyanate compound dry lamination adhesive composition characterized by containing the (C) Product, a laminate using the adhesive, and a secondary battery including the laminate.

By using the adhesive composition of the present invention between a metal layer such as an aluminum foil and an olefin sheet having low polarity, excellent adhesiveness is exhibited even at low temperature aging. As a result, a laminate using the present adhesive can exhibit good moisture resistance, heat resistance, solvent resistance, durability, and the like.
In addition, when the laminate is used as a laminate for a secondary battery, it has excellent resistance to an electrolytic solution using propylene carbonate or ethylene carbonate, and therefore does not cause delamination over time.

The polyolefin resin used in the present invention, for example, hydroxyl group-containing polyolefin resin, the acid group-containing polyolefin resin and the like.

  The hydroxyl group-containing polyolefin resin can be obtained by graft modification or copolymerization of a polyolefin resin with a hydroxyl group-containing (meth) acrylic ester described later or a hydroxyl group-containing vinyl ether. Examples of the polyolefin resin include homopolymers and copolymers of olefins having 2 to 8 carbon atoms, and copolymers of olefins having 2 to 8 carbon atoms and other monomers. Specifically, for example, high density polyethylene (HDPE), low density polyethylene (LDPE), polyethylene such as linear low density polyethylene resin, polypropylene, polyisobutylene, poly (1-butene), poly-4-methylpentene, polyvinyl Cyclohexane, polystyrene, poly (p-methylstyrene), poly (α-methylstyrene), ethylene / propylene block copolymer, ethylene / propylene random copolymer, ethylene / butene-1 copolymer, ethylene / 4-methyl -1-pentene copolymer, α-olefin copolymer such as ethylene / hexene copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methyl methacrylate copolymer, ethylene / Vinyl acetate methyl methacrylate copolymer, Aio Examples thereof include nomer resins. Furthermore, chlorinated polyolefins obtained by chlorinating these polyolefins can also be used.

  Examples of the hydroxyl group-containing (meth) acrylic acid ester include hydroxyethyl (meth) acrylate; hydroxypropyl (meth) acrylate, glycerol (meth) acrylate; lactone modified hydroxyethyl (meth) acrylate, (meth) acrylic acid. Examples include polyethylene glycol and polypropylene glycol (meth) acrylic acid, and examples of the hydroxyl group-containing vinyl ether include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether.

  As the polyolefin resin containing these hydroxyl groups, for example, “Unistol” manufactured by Mitsui Chemicals, Inc. is commercially available.

  The acid group-containing polyolefin resin is a graft modification or copolymerization of a polyolefin resin with a carboxyl group-containing ethylenically unsaturated compound such as acrylic acid or an α, β-unsaturated carboxylic acid (anhydride) such as (anhydrous) maleic acid. To obtain. Further, as the polyolefin resin, the same resins as those used in the production of the above-mentioned hydroxyl group-containing polyolefin resin can be used.

The hydroxyl group-containing polyolefin resin, and acid group-containing polyolefin resin may be used alone or using a plurality of types.

The hydroxyl group-containing polyolefin resin and the acid group-containing polyolefin resin (A) satisfy a weight average molecular weight of 5,000 to 500,000, preferably a weight average molecular weight of 10,000 to 400,000. It is more preferable in terms of excellent adhesion to metal foil or plastic film and resistance to electrolytic solution. The above-described resin containing a hydroxyl group having a molecular weight dissolves in an organic solvent and exhibits outstanding adhesion to a metal foil or plastic film and resistance to electrolyte without significantly impairing the fluidity of the solution.

The hydroxyl group-containing polyolefin resin and the acid group-containing polyolefin resin (A) have a glass transition temperature in order to form a coating film having excellent adhesion on a flexible substrate such as a plastic film or a metal foil. It is more preferable to satisfy −40 to 100 ° C., and in particular, the glass transition temperature is −30 to 90 ° C. The above-described resin containing a hydroxyl group having a glass transition temperature can satisfy a good balance between the base material, adhesiveness, and electrolytic solution resistance.

As the hydroxyl group-containing polyolefin resin, and acid group-containing polyolefin resin, acid group-containing polyolefin resin and a hydroxyl value The acid value of the resin contains an acid group 1~200mgKOH / g is containing a hydroxyl group of 1~200mgKOH / g It is preferably a hydroxyl group-containing polyolefin resin.

Examples of the alcohol-based epoxy compound (B) used in the present invention include those obtained by a reaction between an alcoholic hydroxyl group and an epihalohydrin. As these examples, an aliphatic polyhydric alcohol or polyglycidyl ether of an alkylene oxide adduct of an aliphatic polyhydric alcohol can be used. Examples of aliphatic epoxies include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1, Examples include 6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropane diglycidyl ether, and polyethylene glycol diglycidyl ether. Furthermore , glycidyl ethers of alkylene oxide adducts of bisphenol are exemplified.

Among the above compounds, trimethylolpropane triglycidyl ether and trimethylolpropane diglycidyl ether are preferable from the viewpoint of low viscosity. Furthermore, what reduced the amount of impurity chlorine in an epoxy resin is preferable. Commercial products of aliphatic epoxy include, for example, Epolite 100MF (trimethylolpropane triglycidyl ether) manufactured by Kyoeisha Chemical Co., Ltd. and EX-321L (trimethylolpropane polyglycidyl ether) manufactured by Nagase ChemteX Corporation.

  The blending ratio of the polyolefin resin and the alcohol-based epoxy compound (B) is 0.01 to 30 parts by weight of the alcohol-based epoxy compound (B) with respect to 100 parts by weight of the polyolefin resin (A). It is preferable to do.

  What is necessary is just to select the said isocyanate compound (c2) suitably according to the use used. For example, tolylene diisocyanate (TDI), xylylene diisocyanate, diphenylmethane diisocyanate (MDI), 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, 1 , 3- (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate, polyisocyanate such as triphenylmethane triisocyanate; adducts of these polyisocyanates, burettes of these polyisocyanates, or of these polyisocyanates Derivatives (modified products) of polyisocyanates such as isocyanurates are exemplified.

  In the case of the polyolefin resin containing a hydroxyl group, the blending ratio with the polyisocyanate compound (C) is such that the solid content hydroxyl equivalent (a) of the resin (A) containing a hydroxyl group and the solid isocyanate equivalent of the polyisocyanate compound (c). The equivalent ratio [(a) / (c)] of (c) is 0.01 to 5, preferably 0.1 to 2.0.

  From the viewpoint of viscosity adjustment, the adhesive composition for laminate laminate of the present invention, particularly the main agent, does not have reactivity with the raw materials included therein, and can contain an organic solvent that dissolves the raw materials. . Specifically, for example, hydrocarbon solvents such as toluene and xylene, hydrogenated products of the above hydrocarbon solvents such as methylcyclohexane, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate Examples thereof include ether solvents such as dioxane and ethylene glycol diethyl ether, and aliphatic hydrocarbons such as pentane, hexane and heptane.

  If necessary, the adhesive composition for laminate laminate of the present invention may contain other additives. Examples of the additive include additives generally used in resin compositions that form films and coating films. Examples of additives include leveling agents; inorganic fine particles such as colloidal silica and alumina sol; organic fine particles based on polymethyl methacrylate; antifoaming agents; anti-sagging agents; silane coupling agents; viscosity modifiers; Metal deactivator; Peroxide decomposing agent; Flame retardant; Reinforcing agent; Plasticizer; Lubricant; Rust preventive agent; Fluorescent whitening agent; Inorganic heat absorber; Flameproof agent; A wetting and dispersing agent.

  The adhesive composition for laminate laminates of the present invention is usually prepared by preparing a main agent premix in which components other than the polyisocyanate compound that is a curing agent are blended in advance, and mixing this with a polyisocyanate compound. I can do it.

The adhesive composition for laminate laminate of the present invention can be applied to various substrates and dried to laminate an adhesive cured film on the substrate. The coating amount on the substrate is not particularly limited, but for example, selecting from the range of 1 to ²⁰ g / m ² , especially 3 to 10 g / m ² gives excellent weather resistance and the like in a small amount. It is preferable in that it can be performed. For this coating, for example, a gravure coater, a micro gravure coater, a reverse coater, a bar coater, a roll coater, a die coater or the like can be used.

  Moreover, it is preferable that the laminated body which apply | coated the adhesive composition for laminate laminated bodies of this invention performs aging after preparation. The aging conditions are from room temperature to 100 ° C. and for 12 to 240 hours, during which the curing reaction proceeds.

Examples of the base material in this case include paper, olefin resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, and carbonate resin. And polyamide resin, polyimide resin, polyphenylene ether resin, synthetic resin film obtained from polyphenylene sulfide resin and polyester resin, copper foil, metal foil such as aluminum foil, and the like. The thickness of the substrate is not particularly limited, and can be selected from, for example, 10 to 400 μm. However, the adhesive composition for laminate laminate of the present invention can be applied in a small amount and dried at a low temperature in a short time. Therefore, it can be applied to a base material having a softening temperature of 180 ° C. or less at 20 to 100 μm because it exhibits excellent adhesion without giving any influences such as warping and settling.

  The laminate of the present invention comprises the laminate adhesive composition of the present invention comprising a metal layer such as an aluminum foil and one or several plastic layers such as a polyolefin sheet such as polyethylene and polypropylene, and a polyester such as polyethylene terephthalate. It is obtained by pasting together.

  And the adhesive composition for laminates of the present invention can be applied to any suitable solvent or dispersant such as, for example, ester solvents, ketone solvents, aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, etc. The adhesive layer can be formed by dissolving / dispersing in a ratio and applying and drying on a metal foil using a known coating method such as a roll coating method, a gravure coating method, or a bar coating method.

  The dry coating weight of the laminating adhesive composition of the present invention is preferably in the range of 0.5 to 20.0 g / m2. If it is less than 0.5 g / m 2, there will be a difficulty in continuous uniform application. On the other hand, if it exceeds 20.0 g / m 2, the solvent detachability after application will be reduced, workability will be significantly reduced, and there will be a problem of residual solvent. Arise.

After the adhesive composition for laminating of the present invention is applied to one of the metal foils, the laminated body of the present invention is obtained by stacking the plastic layers and bonding them by dry lamination (dry laminating method). The temperature of the laminate roll is preferably about room temperature to about 120 ° C., and the pressure is preferably about 1 to 300 kg / cm 2.
Moreover, it is preferable that the laminated body of this invention performs aging after preparation. Aging conditions are between room temperature and 100 ° C. for 12 to 240 hours, during which adhesive strength occurs.

  The laminate of the present invention can be used as an electrolyte solution sealing film or an electrode part protective film of a primary or secondary battery. In this case, the laminate is used by contacting the plastic layer side with a polar organic solvent and / or salts. Especially when used in contact with a non-aqueous electrolyte containing a polar organic solvent and salt, it is particularly suitable as a secondary battery electrolyte sealing film or secondary battery electrode part protective film for non-aqueous electrolyte batteries, solid batteries, etc. Can be used. In this case, it can be used as a battery sealing bag by folding and heat-sealing so that the plastic layers face each other. Since the adhesive used in the present invention is excellent in heat sealability, it prevents leakage of the non-aqueous electrolyte and enables long-term use as a battery.

  Examples of the polar organic solvent include aprotic polar solvents such as alkyl carbonates, esters, and ketones. Specifically, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3- Examples include dioxolane, 4-methyl-1,3-dioxolane, methyl formate, 4-methyl-1,3-dioxomethyl formate, methyl acetate, and methyl propionate.

  Examples of the salt include alkali metal salts such as lithium salt, sodium salt and potassium salt. For batteries, lithium salts such as LiPF6, LiBF4, and Li-imide are generally used.

  The non-aqueous electrolyte is obtained by dissolving 0.5 to 3 mmol of the alkali metal salt in an aprotic polar organic solvent such as a cyclic carbonate, a chain carbonate, or a mixture thereof.

  The laminate of the present invention does not cause delamination of the metal layer, adhesive layer, and plastic layer even when used in contact with the polar solvent and / or salts, particularly a nonaqueous electrolyte that is a mixture thereof, for a long period of time. Can be used.

  The battery of this invention is a battery which has a battery electrolyte solution sealing film or battery electrode part protective film which consists of the said laminated body. The battery of the present invention can be used stably as a battery for a long time since the film does not cause delamination and can prevent leakage of the nonaqueous electrolyte.

  As described above, the laminate of the present invention has excellent adhesion between the metal layer and the plastic layer and excellent durability against polar organic solvents or salts, and does not cause delamination even when contacted with a nonaqueous electrolyte or the like. . Therefore, a battery using such a laminate as a battery electrolyte sealing film or a battery electrode protection film, and a secondary battery using a secondary battery electrolyte sealing film or a secondary battery electrode protection film are: Can be used stably for a long time.

Hereinafter, the present invention will be specifically described with reference to examples. In the examples, “part” is based on weight.

The number average molecular weight of the hydroxyl group-containing resin (A) used in the present invention was determined under the following conditions using a gel permeation chromatograph (GPC): HLC-8220 manufactured by Tosoh Corporation
Detector: RI (differential refractometer)
Measurement conditions: Column temperature 40 ° C. Solvent tetrahydrofuran The glass transition temperature of the hydroxyl group-containing resin (A) used in the present invention was determined under the following conditions.

Measuring device: DSC220C manufactured by Seiko Electronics Corporation
Measuring method: DSC (Differential Scanning Calorimetry) method

  Evaluation of the adhesiveness etc. of the laminate adhesive of this invention was performed by the following method. The obtained results are shown in Tables 1 and 2.

Substrate: Polyolefin film “ZK-93KM” 70 μm (manufactured by Toray Film Processing Co., Ltd.) and aluminum foil Application: Bar coater drying conditions: 80 ° C., 60 seconds Aging conditions: 40 ° C., 3 days Application amount: 5 g / m 2 (Dry )
Adhesive strength: Tensilon test manufactured by A & D Co., Ltd. 15 mm width 180 ° peel strength Electrolytic resistance: ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate = 1/1/1
Adhesive strength retention after immersion at 25 ° C. for 14 days ○: 90% or more, Δ: 90 to 70%, ×: 70% or less

The various materials used in the table were as follows.
Unistor P-901 (manufactured by Mitsui Chemicals) hydroxyl group-containing polyolefin resin, solid content hydroxyl value 50 mg KOH / g heating residue 20%
Unistor P-902 (manufactured by Mitsui Chemicals) acid group-containing polyolefin resin, solid content acid value 55 mg KOH / g heating residue 22%
Unistor P-801 (manufactured by Mitsui Chemicals) hydroxyl group-containing polyolefin resin, solid content hydroxyl value 40 mgKOH / g heating residue 16%
Cureazole 2E4MZ (manufactured by Shikoku Chemicals Co., Ltd.) Imidazole Non-volatile content 100%
Denacol EX-321 (manufactured by Nagase ChemteX Corporation) epoxy resin, epoxy equivalent 140 nonvolatile content 100%
Epicron 860 (manufactured by DIC Corporation) bisphenol A type epoxy resin, epoxy equivalent 240 nonvolatile content 100%
Lupranate M20S (manufactured by BASF) polyisocyanate compound, NCO% 31.0 Nonvolatile content 100%
Death Module N3800 (manufactured by Sumika Bayer Urethane Co., Ltd.) polyisocyanate compound, NCO% 10.9 Nonvolatile content 100%

Claims (8)

Hydroxyl-containing polyolefin resin and acid group-containing polyolefin resin (A), the alcohol-based epoxy compound (B), and a polyfunctional isocyanate compound (C) Dry lamination adhesive composition characterized by containing a. Hydroxyl group-containing polyolefin resin and acid group-containing polyolefin resin (A) are modified polyolefin resin containing an acid group having an acid value of 1 to 200 mgKOH / g and / or a modified polyolefin containing a hydroxyl group having a hydroxyl value of 1 to 200 mgKOH / g The adhesive composition for dry lamination according to claim 1, which is a resin. The alcohol-based epoxy compound (B) is an epoxy compound having two or more epoxy groups in one molecule and one or more hydroxyl groups in one molecule and having a weight average molecular weight of 3000 or less. Or the adhesive composition for dry lamination of 2. The adhesive composition for dry lamination according to claim 1, wherein the alcohol-based epoxy compound (B) is blended at a ratio of 0.01 to 100 parts by weight with respect to 100 parts by weight of the polyolefin resin (A). The adhesive composition for dry lamination according to claim 4, wherein the polyfunctional isocyanate compound (C) is blended at a ratio of 0.1 to 30 parts by weight with respect to 100 parts by weight of the polyolefin resin (A).
The adhesive composition for dry lamination according to any one of claims 1 to 5, further comprising a thermoplastic elastomer and a tackifier, a catalyst, and a phosphoric acid compound. A laminate in which the adhesive for dry lamination according to any one of claims 1 to 6 is used between a metal layer and a polyolefin resin layer.   A secondary battery comprising the laminate according to claim 7.