JPH08106885A - Film for sealing material of thin battery and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] The sealing material improves the moisture resistance, heat resistance, and adhesion of thin batteries. [Structure] A battery element interposed between a pair of terminal plates is sealed at the peripheral edge portion of the terminal plates, so that both outer layer side heat-adhesive polyolefins are thermally bonded to the pair of terminal plates 1 and 6. A sealing material 5 having a three-layer structure is used, which is composed of a layer (A layer) and an intermediate layer (B layer) interposed between these A layers and made of a specific polyamide. The heat-adhesive polyolefin includes a modified polyolefin having hot-melt adhesive property, and the polyamide of the layer B is (1) lactam having 7 or more carbon atoms such as nylon 11 and nylon 12, aminocarboxylic acid, and aliphatic diamine. Or an aliphatic polyamide derived from an aliphatic dicarboxylic acid, or (2)
Polyamides having an aromatic ring in the main chain such as polymeta-xylylene adipamide are included. The layer A can maintain high adhesion to the terminal board, and the layer B can improve heat resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for a sealing material for a thin battery such as a paper battery, a method for producing the film, a sealing material using the film, and a thin battery.

[0002]

2. Description of the Related Art Thin batteries such as paper batteries, paper lithium batteries and plate batteries are used as a power source for small electronic devices such as IC cards, memory cards, RAM cards, ID cards, card calculators and card clocks. ing. The paper lithium battery is, for example,
It has a structure in which a battery element (for example, a positive electrode mixture, a separator and a lithium negative electrode material) is sandwiched between a thin plate-shaped positive electrode terminal plate also serving as an electrode terminal and a negative electrode terminal plate.

Since such a paper lithium battery has a thickness of at most about 0.5 mm, its sealing structure is different from that of a button type alkaline battery in which an insulating gasket is sandwiched between terminal plates. different. That is, in a paper lithium battery, normally, a frame-shaped sealing material made of an insulating material such as polyolefin is arranged on the peripheral portions of the positive electrode terminal plate and the negative electrode terminal plate, and the peripheral portion of the battery element is heated and pressed. A sealing structure for heat-sealing the peripheral portion of the terminal plate with a sealing material is adopted.

The sealing material for such a thin battery is moisture-proof to prevent water from entering the battery element, has high thermal adhesiveness to the terminal plate, and is high even when the battery is exposed to a high temperature environment. Heat resistance is required to maintain the adhesive strength. Further, the adhesiveness is required to be not only the above heat-resistant adhesiveness but also the adhesiveness not to be lowered by the action of moisture or load. Furthermore, the sealing material is also required to have high chemical resistance to an electrolytic solution.

Japanese Unexamined Patent Publication (Kokai) No. 5-182649 discloses a thin battery using an exterior material having a heat-fusible layer such as modified polypropylene and a metal layer, and Japanese Unexamined Patent Publication No. 2-250257.
JP-A-2-234344 and JP-A-2-220
Japanese Patent No. 351 proposes to use a monolayer film of polyolefin, modified polyethylene, polyisobutylene modified polyethylene, or the like as a sealing material. These sealing materials show good thermal adhesive strength to the terminal board. However, among these sealing materials, modified polyethylene has a low Vicat softening point of about 60 to 70 ° C, and even modified polypropylene has a Vicat softening point of 110 to 130 ° C.
The heat resistance is inferior.

On the other hand, when a polymer having high heat resistance is used,
Thermal adhesiveness is reduced. Therefore, it is difficult to achieve both properties of heat resistance and thermal adhesiveness. For example, it is conceivable to use a polyamide hot melt adhesive film having a high melting point such as nylon 12 or nylon 6 in order to improve heat resistance. When the polyamide-based hot melt adhesive film is used, a battery having a high initial adhesive strength can be obtained. However, polyamide has high hygroscopicity and moisture permeability. Therefore, not only the adhesive strength is greatly reduced by the moisture, but also the invading moisture deteriorates the battery element, the electromotive force is significantly reduced, and the life of the battery is shortened.

When a film having a high melting point is used among the polyester hot melt adhesive films, the heat resistance can be improved, but the adhesive strength to the terminal board is small. Moreover, since the water vapor permeability of polyester is still high, it is difficult from a practical point of view to utilize the battery element in association with the terminal plate for sealing.

As described above, since the conventional sealing material is deteriorated in any of the moisture-proof property, the adhesive property and the heat resistance, there is a limit in improving the sealing property and greatly improving the battery life. .

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a film for a sealing material, which is capable of satisfying all the characteristics of moisture resistance, adhesiveness and heat resistance, and a method for producing the film.

Another object of the present invention is to provide a film for a sealing material which is excellent in heat resistance despite the use of polyolefin and a method for producing the film.

Still another object of the present invention is to provide a sealing material having the above-mentioned excellent properties and a battery using the sealing material.

[0012]

As a result of intensive studies to solve the above-mentioned problems, the present inventor forms an intermediate layer made of a specific polyamide between the heat-adhesive polyolefin layers to enhance the heat resistance while taking advantage of the polyolefin. The present invention has been completed by finding out that it is possible.

That is, the film for a sealing material of the present invention is
A film for a sealing material for sealing a battery element interposed between a pair of terminal plates at a peripheral portion of the terminal plate, wherein both outer layers are heat-bonded for thermal bonding to the pair of terminal plates. And a heat-adhesive polyolefin layer and an intermediate layer consisting of the polyamide of the following (1) or (2) and having at least a three-layer structure.

(1) Aliphatic polyamide derived from lactam having 7 or more carbon atoms, aminocarboxylic acid, aliphatic diamine or aliphatic dicarboxylic acid (2) Polyamide having aromatic ring in main chain The heat-adhesive polyolefin is A polyolefin having a high thermal adhesive strength, for example, 1.5 Kg / 15 mm or more, can be used for the terminal plate, and often has hot melt adhesiveness. The intermediate layer can be made of, for example, an aliphatic polyamide such as nylon 11 or nylon 12, or an aromatic polyamide containing m- or p-xylylenediamine as a diamine component. The polyamide constituting the intermediate layer is, for example, 10% or more than the thermoadhesive polyolefin.
In many cases, it has a high softening point of ℃ or more.

The thicknesses of the thermoadhesive polyolefin layer (A) and the intermediate layer (B) can be selected within a range that does not impair the adhesiveness, heat resistance, etc. For example, the thickness ta of the thermoadhesive polyolefin layers of both outer layers is ta. Is about 5 to 20 μm, and the thickness ti of the intermediate layer is often ti = 2 × ta × 1.2 (μm) or more.

Such a film for a sealing material is a method of laminating a hot-melt adhesive polyolefin layer, a polyamide intermediate layer, and a hot-melt adhesive polyolefin layer, which comprises (1) a lactam having 7 or more carbon atoms and an aminocarboxylic acid. Produced by a method of forming an intermediate layer using an aliphatic polyamide derived from an acid, an aliphatic diamine or an aliphatic dicarboxylic acid, or (2) a resin composition containing as a main component a polyamide having an aromatic ring in the main chain. it can.

The sealing material of the present invention is composed of the film formed in a frame shape. Further, the thin battery of the present invention, a battery element composed of a positive electrode mixture, a separator and a negative electrode material, a pair of terminal plates for holding the battery element, and the battery element at the peripheral portion of the terminal plate. A battery composed of a sealing material for sealing, wherein the sealing material is composed of a laminated body having at least a three-layer structure composed of the following A layer and B layer.

A layer: a heat-adhesive polyolefin layer constituting both outer layers B layer: an intermediate layer interposed between A layers, (1) a lactam having 7 or more carbon atoms, an aminocarboxylic acid, an aliphatic diamine or an aliphatic An intermediate layer composed of an aliphatic polyamide derived from a dicarboxylic acid or (2) a polyamide having an aromatic ring in its main chain Note that, in the present specification, "thermal adhesiveness" means adhesiveness due to melting or softening. Of the adhesiveness, and "adhesive strength" is measured according to JIS K 6854.
It means 0 ° peel strength. The "Vicat softening point" means the softening point measured by the method specified in JIS K7206, and the "melting point" means the thermal differential scanning calorimeter (D
SC) means the melting peak temperature (Tpm) when measured at a temperature rising rate of 10 ± 1 ° C./min according to the measuring method specified in JIS K 7121. Also, "moisture permeability"
Means a value measured by the method specified in ASTM F 1249, and is a value when converted to a thickness of 25 μm. Further, the "film" means a two-dimensional structure sometimes called a sheet.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as needed.

FIG. 1 is an exploded perspective view showing a paper lithium battery which is an example of the present invention. This battery includes a pair of terminal plates made of a conductive material such as stainless steel, that is, a positive electrode terminal plate 1 and a negative electrode terminal plate 6,
The battery element is interposed between the pair of terminal plates 1 and 6. The battery element is composed of a sheet-shaped positive electrode mixture 2 containing an anode active material, a separator 3 impregnated with an electrolytic solution, and a negative electrode material 4 made of lithium or the like. Then, the battery element is sealed at the peripheral edges of the terminal plates 1 and 6 with a frame-shaped sealing member 5 that can be heat-bonded between the pair of terminal plates 1 and 6.

The terminal plate is a conductive material that can be thinned,
In particular, it is often formed of a flexible conductive metal film having a large mechanical strength without being deteriorated by the electrolytic solution.
Such conductive metals include, for example, aluminum, copper, nickel, titanium, stainless steel, nickel plated stainless steel and the like. Of these conductive metals, nickel, stainless steel, nickel-plated stainless steel, etc. are often used. The thickness of the terminal plate corresponding to the conductive metal film is, for example, 0.01 mm to 0.1 mm, preferably 0.01 mm to 0.07 mm. If the thickness is less than 0.01 mm, the strength is low and defects are likely to occur,
If it exceeds 0.1 mm, the weight of the battery tends to increase.

The members constituting the battery element are not limited to the above, but can be selected according to the type of battery. The battery element will be described by taking the above paper lithium battery as an example. Examples of the positive electrode active material of the positive electrode mixture include TiS ₂ and Mo.
Metal chalcogenides having a layered structure such as S ₃ , NbSe ₃ , VSe ₂ ; CoO ₂ , Cr ₃ O ₅ , TiO ₂ ,
CuO, V ₃ O ₆ , Mo ₃ O, V ₂ O ₅ , V ₂ O ₅ (・
P ₂ O _5), metal oxides such as _{Mn 2 O (· Li 2 O} ); such a conjugated polymer having conductivity such as polyacetylene. Preferred anode active materials include V ₂ O
₅ , MnO _{2 and the} like are included. Such an anode active material can be used in combination with a binder such as a fluororesin (eg, polytetrafluoroethylene) or a conductive agent such as conductive carbon black.

As the separator, for example, a polyolefin-based porous material having a liquid retaining property such as polypropylene nonwoven fabric can be used. As the negative electrode material, an alkali metal such as metallic lithium (for example, lithium foil), a carrier carrying an alkali metal, or the like can be used.

The solvent of the electrolytic solution is a non-aqueous solvent such as propylene carbonate, ethylene carbonate,
Aprotic solvents such as tetrahydrofuran, dioxolane, sulfolane, dimethoxyethane, dimethylsulfoxide, acetonitrile, N, N-dimethylformamide, diethylene glycol, dimethyl ether and the like can be mentioned. In a paper lithium battery, as the electrolytic solution, LiClO ₄ , LiBF ₄ , Li
_{ClF 4, LiAsF 6, LiSbF 6} , LiCl, L
A solvent in which a lithium salt such as iI is dissolved is often used.

As described above, the sealing material (1) exhibits a high adhesive strength to the positive and negative electrode terminal plates by heat fusion, and (2) prevents the permeation or permeation of water, and the positive electrode composite material. And (3) protect the lithium negative electrode material, (3) the adhesive strength does not decrease even when exposed to the use environment or the high temperature environment in the manufacturing process (high heat resistance adhesiveness), (4) chemical resistance to electrolyte Is required to be high.

In order to meet these required performances, the sealing material of the present invention is not a single layer but a laminated body of a plurality of layers. That is, as shown in FIG. 2, the sealing material is a thermoadhesive polyolefin layer 11, 13 (hereinafter, simply referred to as A layer) that forms both outer layers for thermally adhering to the pair of terminal boards 1, 6. In some cases) and the intermediate layer 12 (hereinafter sometimes simply referred to as B layer) interposed between these heat-adhesive polyolefin layers, and has at least a three-layer structure (A layer / B layer / Layer A). The A layers 11 and 13 impart high adhesiveness, moisture resistance and chemical resistance, and the B layer 12 as an intermediate layer imparts high heat resistance, moisture resistance and chemical resistance. The sealing material 5 is obtained from a sealing material film having a laminated structure corresponding to the structure shown in FIG.

The heat-adhesive polyolefin constituting the layer A may be a homopolymer or copolymer of α-olefin. Examples of the α-olefin include ethylene, propylene, 1-butene, 4-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-hexene. -Octene, 1
-Decene, 1-dodecene, etc. are included.

Preferred heat-adhesive polyolefins include modified polyolefins obtained by modifying the above α-olefin homopolymers or copolymers. In the modified polyolefin, the α-olefin homopolymer or copolymer,
Homo- or copolymers of α-olefin having 2 to 6 carbon atoms, preferably about 2 to 4, such as polyethylene, polypropylene, ethylene-propylene copolymer, propylene-
Ethylene copolymer, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, ethylene-3-methylpentene-1 copolymer, ethylene-propylene- 3-methylpentene-1 copolymer, ethylene-4-methylpentene-1
A copolymer, an ethylene-propylene-4-methylpentene-1 copolymer, an ethylene-butene-1-3-methylpentene-1 copolymer and the like can be mentioned. The modified polyolefin is preferably modified polypropylene in order to enhance heat resistance.

The modified polyolefin can be composed of a copolymer of one or more kinds of the above α-olefin and a copolymerizable vinyl monomer. Examples of the copolymerizable vinyl monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid and angelic acid; Ethylenically unsaturated carboxylic acid anhydrides such as maleic acid, citraconic anhydride, and itaconic anhydride; acrylic acid esters, methacrylic acid esters (eg, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid) Butyl,
Hexyl (meth) acrylate, (meth) acrylic acid 2-
Ethylhexyl, alkyl (meth) acrylates such as octyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, hydroxyl group-containing (meth) acrylates such as 2-hydroxypropyl (meth) acrylate, (meth) (Meth) acrylate having a functional group such as glycidyl group-containing (meth) acrylate such as glycidyl acrylate; carboxylic acid vinyl ester such as vinyl acetate and vinyl propionate; cyclic olefin such as norbornene and cyclopentadiene;
Chain conjugated diene such as 1,3-butadiene and isoprene, chain non-conjugated diene such as 1,4-hexadiene and 1,6-octadiene, cyclic non-conjugated such as dicyclopentadiene, methyltetrahydroindene and 5-vinylnorbornene Examples include dienes such as diene and cyclic conjugated dienes such as 2,3-diisopropylidene-5-norbornene. The copolymerizable monomer may be used alone or in combination of two or more.

Preferred modified polyolefins are carboxylic acid modified polyolefins, acid anhydride modified polyolefins such as maleic anhydride, and (meth) acrylates such as ethyl acrylate.
In many cases, acrylate modified polyolefin, glycidyl modified polyolefin such as (meth) acrylic acid glycidyl ester, vinyl modified polyolefin such as vinyl acetate and the like.

The modified polyolefin as described above is, for example, manufactured by Mitsui Petrochemical Co., Ltd. under the trade name "Admer".
"Nukurel", product name "MODIC" from Mitsubishi Petrochemical Co., Ltd., product name "Novatech A" from Mitsubishi Kasei Co., Ltd.
P ”, trade name“ Rescue Pearl ”from Nippon Petrochemical Co., Ltd.
"N Polymer" is commercially available from Sumika Atokem Co., Ltd. under the trade name "Bondaine" and Sumitomo Chemical Co., Ltd. under the trade name "Bond Fast". Among these commercially available modified polyolefins, in order to improve heat resistance, modified polyolefins containing polypropylene as a main component (modified polypropylene), for example, "Admer" QF series, "Modik" P series, "Novatech AP" P series Are preferred.

The heat-adhesive strength of the heat-adhesive polyolefin constituting the layer A to the positive and negative electrode terminal plates may be within a range capable of preventing leakage of the electrolytic solution and deterioration of the battery element.
1.5 kg / 15 mm or more, preferably 2.0 kg / 1
It is 5 mm or more, more preferably 2.5 kg / 15 mm or more. If the adhesive strength is less than 1.5 kg / 15 mm, the battery may be broken depending on the environment in which the battery is used.

The Vicat softening point of the heat-adhesive polyolefin is, for example, 70 ° C. or higher, preferably 80 to 160 ° C.
More preferably, it is often about 90 to 150 ° C. In order to improve the heat resistance of the sealing material, the Vicat softening point of the thermoadhesive polyolefin is 100 ° C. or higher, preferably 1
00-160 ° C (for example, 110-155 ° C), more preferably 110-150 ° C (for example, 120-145).
C.) is preferable.

The adhesive strength of the heat-adhesive polyolefin to the positive electrode terminal plate and the negative electrode terminal plate is, for example, humidity,
Especially under high temperature and high humidity environment (for example, 40 ℃ 90% RH, 6
20 days or more, preferably 40 days under 0 ° C. 90% RH condition
It is required that it does not decrease over a day or more, more preferably 100 days or more) and that it does not decrease due to an electrolytic solution such as propylene carbonate. The thermoadhesive polyolefin used in the present invention can sufficiently withstand such required performance.

The outer layer of the film for sealing material and both outer layers of the sealing material may be composed of the same thermoadhesive polyolefin or different thermoadhesive polyolefins.

The feature of the present invention is that, in addition to the sealing material film and the sealing material being composed of a laminate having a three-layer structure, the intermediate layer is composed of a specific polyamide so that the outer layer is heat-bonded. Adhesiveness to hydrophilic polyolefin,
The point is to increase heat resistance while maintaining chemical resistance and moisture resistance.

The polyamide constituting the layer B includes (1) an lactam having 7 or more carbon atoms, an aliphatic carboxylic acid derived from an aminocarboxylic acid, an aliphatic diamine or an aliphatic dicarboxylic acid, and (2) an aromatic group in the main chain. Included are ring-containing polyamides. Since such a polyamide has a component having a carbon number of 7 or more or a component having an aromatic ring as a constituent component, it has excellent adhesiveness to a heat-adhesive polyolefin and high moisture resistance compared to conventional polyamides. There is.

Examples of the component having 7 or more carbon atoms (hereinafter referred to as C7-component) which constitutes the aliphatic polyamide (1) include capryl lactam, enantolactam, nonalactam, decalactam, undecalactam, dodecaractam (laurolactam). ), Tetradecalactam, hexadecalactam, and other lactams having about 7 to 16 carbon atoms; aminoheptanoic acid, aminooctanoic acid, aminononanoic acid, aminodecanoic acid, aminoundecanoic acid, aminododecanoic acid, aminotetradecanoic acid, aminohexadecanoic acid, etc. An aminocarboxylic acid having about 7 to 16 carbon atoms; 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-
Diaminononane, 1,10-diaminodecane, 1,12
-Diaminododecane, 1,14-diaminotetradecane, 1,16-diaminohexadecane and the like having 7 to 7 carbon atoms
About 16 aliphatic diamines; pimelic acid, suberic acid,
Aliphatic dicarboxylic acids having about 7 to 18 carbon atoms such as azelaic acid, sebacic acid, dodecanedioic acid and octadecanedioic acid are included. These components may be one kind or two or more kinds.

The aliphatic polyamide (1) is used for ring-opening polymerization of the lactam, polycondensation of aminocarboxylic acid, polycondensation of diamine and dicarboxylic acid, copolymerization of these components (for example, aminocarboxylic acid, diamine and dicarboxylic acid). (Copolymerization with acid) and the like.

If necessary, the aliphatic polyamide (1) may be a lactam other than the above, an aminocarboxylic acid,
It may contain a diamine, a dicarboxylic acid or the like as a constituent unit. For example, copolymerizable diamines include trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,2.
4-trimethylhexamethylenediamine, 2,4,4-
Aliphatic diamines such as trimethylhexamethylenediamine; alicyclic diamines such as bis (4-amino-3-methylcyclohexyl) methane and piperazine.
As the copolymerizable dicarboxylic acid, cyclohexane-
Alicyclic dicarboxylic acids such as 1,4-dicarboxylic acid and cyclohexane-1,3-dicarboxylic acid; aliphatic dicarboxylic acids such as glutaric acid and adipic acid; fatty acids such as linolenic acid and the like having about 8 to 24 carbon atoms Examples thereof include dimerized fatty acids obtained by polymerizing unsaturated natural or synthetic basic fatty acids. Examples of copolymerizable aminocarboxylic acids include aminoheptanoic acid and aminohexanoic acid. Copolymerizable lactams include, for example, butyrolactam, valerolactam, caprolactam, and the like.

In the aliphatic polyamide (1), the C
The content of the 7-component is usually 30 mol% or more (eg 4
0 to 100 mol%), preferably 50 mol% or more (eg 55 to 100 mol%), more preferably 60 mol% or more (eg 70 to 100 mol%).

The preferred aliphatic polyamide (1) includes lactam, aminocarboxylic acid, aliphatic diamine or aliphatic dicarboxylic acid having 10 or more carbon atoms (for example, 10 to 14 carbon atoms), and more preferably 10 to 12 carbon atoms. Included are polyamides derived from More preferred polyamide (1) includes nylon 10 derived from ω-lauryllactam or ω-aminooctanoic acid, nylon 11 derived from ω-undecalactam or ω-aminoundecanoic acid, ω-laurolactam or ω. -Nylon 12 derived from aminododecanoic acid, and these monomer components and other monomers (for example, caprylolactam, hexamethylene adipamide, hexamethylene sebacamide, hexamethylene dodecamide, etc.) And the copolymers thereof are included.
Of these, nylon 11 and nylon 12 are preferable.

The melting point of the aliphatic polyamide (1) is usually 1.
60 ° C or higher (for example, about 160 to 260 ° C), preferably 165 ° C or higher (for example, about 165 to 250 ° C),
More preferably 170 ° C. or higher (for example, 170 to 220)
℃).

The aliphatic polyamide (1) as described above is
For example, it is marketed under the trade name “DAIAMID” from Daicel Huls Co., Ltd. and under the trade name “Rilsan” from Toray Industries, Inc.

Polyamide having an aromatic ring in the main chain (2)
Contains a component having an aromatic ring as at least one of the diamine component and the dicarboxylic acid component. The component having an aromatic ring, for example, phenylenediamine,
Aromatic diamines such as m-xylylenediamine and p-xylylenediamine; phthalic acid, phthalic anhydride, and aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid.

The polyamide (2) may contain a component other than the above as a constituent unit as long as it has an aromatic ring in the main chain. Examples of such other components include lactams (eg, caprolactam), aliphatic diamines (eg, hexamethylenediamine, etc.), alicyclic diamines (eg, piperazine, etc.), which constitute the aliphatic polyamide, and fats. Group dicarboxylic acids (eg, adipic acid, sebacic acid, suberic acid, etc.), alicyclic dicarboxylic acids, dimerized fatty acids, aminocarboxylic acids (eg, aminoheptanoic acid, aminooctanoic acid) and the like are used.
These components can be used alone or in combination of two or more.

The preferred polyamide (2) is a polyamide in which at least one component of diamine and dicarboxylic acid is aromatic, particularly lactam having 4 to 16 carbon atoms (preferably 6 to 12 carbon atoms) and aliphatic diamine. , A polyamide in which a part of the aliphatic dicarboxylic acid is substituted with an aromatic group is included. Examples of such a polyamide (2) include polymetaxylene adipamide, polymetaxylene sebacamide, polymetaxylene sveramide, and co-polymerization of m-xylylenediamine, p-xylylenediamine and adipic acid. Examples thereof include a combination and a copolymer of m-xylylenediamine, adipic acid and isophthalic acid. Further, the polyamide (2) may contain an aminocarboxylic acid as a constituent component, and such a polyamide copolymer has m
-Xylylenediamine, adipic acid, isophthalic acid and ε
-A copolymer with aminocaproic acid and the like are included.

Polyamide (2) having an aromatic ring as described above is, for example, nylon 6 / 6T or nylon MXD6.
(For example, Mitsubishi Gas Chemical Co., Inc., trade name "MX Nylon"), nylon 6T / 6I (for example, Mitsubishi Kasei Co., Ltd.)
Manufactured by DuPont-Sealer Co., Ltd., trade name "PA"), nylon 12T, and the like. In addition, T is terephthalic acid, I is isophthalic acid, and MXD is m-xylylenediamine. Of these, nylon MXD6 and the like are preferable.

In the polyamide (2) having an aromatic ring, the content of aromatic diamine is usually 25 mol% or more (for example, 30 to 100) based on the total amount of diamine components.
Mol%), preferably 35 mol% or more (eg 40 to 1)
00 mol%), more preferably 50 mol% or more (for example, 55 to 100%). The content of the aminocarboxylic acid component in the polyamide copolymer can be appropriately selected depending on the desired characteristics, but is usually 35 mol% or less, preferably 25 mol% or less, and more preferably 20 mol% or less per total amide repeating unit. It is not more than mol%.

The polyamide (2) may be amorphous, but is preferably crystalline.

The melting point of the aromatic ring-containing polyamide (2) is usually 170 ° C. or higher (for example, 180 to 300).
℃), preferably 190 ℃ or more (for example, 200 ~ 28
0 ° C.), more preferably 210 ° C. or higher (eg 210 ° C.)
~ 250 ° C).

The intermediate layer may be composed of polyamide (1) or polyamide (2), but may contain both of them. The ratio of the two can be appropriately selected according to the desired characteristics, and can be selected from the range of, for example, about 50/50 to 95/5 (weight ratio). Further, the intermediate layer may contain another polyamide in addition to the polyamide (1) and / or the polyamide (2). Further, the layer A may contain a heat-adhesive polyolefin or other polymer within a range that does not impair properties such as heat resistance. The total amount of polyamide (1) and / or polyamide (2) in the intermediate layer is usually 50% by weight or more (for example, 55 to 100% by weight), preferably 60% by weight or more, with respect to the total amount of the polymer constituting the intermediate layer. (Eg, 65 to 100% by weight), more preferably about 70% by weight or more (eg, 70 to 100% by weight).

The Vicat softening point of the polyamide composing the layer B is not particularly limited as long as it does not impair the heat resistance, but it is preferably at least higher than that of the thermoadhesive polyolefin of the layer A. In order to increase the heat resistance of the sealing material film and the sealing material, the Vicat softening point of the polyamide forming the B layer is 10 ° C or higher than that of the thermoadhesive polyolefin of the A layer when measured according to JIS K 7206 ( For example, it is preferably 10 to 180 ° C.), preferably 15 ° C. or higher (eg 15 to 170 ° C.), more preferably 20 ° C. or higher (eg 20 to 140 ° C.).

The Vicat softening point of the polyamide constituting the B layer can be selected according to the softening point of the heat-adhesive polyolefin constituting the A layer within a range not impairing the heat resistance.
The temperature is often 110 to 250 ° C, preferably 130 to 230 ° C. Preferred polyamides are 145 ° C. or higher (eg 150 to 240 ° C.), preferably 155 ° C. or higher (eg 160 to 230 ° C.), more preferably 17
It often has a Vicat softening point of about 0 ° C. or higher (for example, 170 to 220 ° C.).

The moisture permeability of the polyamide forming the B layer can be selected within a range that does not impair the moisture resistance. In order to enhance the moisture resistance of the film and the sealing material, the moisture permeability of the polyamide forming the layer B is 125 g / m ² · day or less (e.g., 1 to 115 g / day) when measured according to ASTM F1249. m ² / day), preferably 10
5 g / m ² · day or less (e.g., 1 to 100 g / m about ² · day), more preferably less than ² · day 65 g / m (e.g., 5 to 50 g / m of about ² · day). The moisture vapor transmission rate of the polyamide constituting the layer B is normally 5 to 5 in terms of 25 μm.
110g / m ² · day, preferably in many cases is about ² per day 5~60g / m.

To the heat-adhesive polyolefin layer (A layer) and the polyamide intermediate layer (B layer), a polymer of the other layer or another polymer is added as long as the adhesiveness and heat resistance are not impaired. Good. In addition, each layer has an additive, for example,
Stabilizers such as antioxidants and ultraviolet absorbers, plasticizers, fillers, flame retardants, antistatic agents, colorants, tackifiers and the like may be added.

The thickness of the film and sealing material of the present invention is
It can be selected within a range that does not impair thermal adhesion, heat resistance, moisture resistance, chemical resistance, etc., and is, for example, 25 to 200 μm, preferably 40 to 150 μm, and more preferably 50 to 120 μm.
It is a degree. If the thickness of the film and the sealing material is too thin, the heat-adhesive polyolefin layer may partially adhere during heat-adhesion with the terminal board, resulting in poor adhesion.The heat-adhesive polyolefin layer is effectively used for heat-adhesion. If it becomes too thick and too thick, it becomes impossible to obtain a thin battery.

The thickness of the heat-adhesive polyolefin layer constituting both outer layers and the thickness of the polyamide layer as the intermediate layer are as follows.
It can be selected within a range that does not impair heat resistance. The thickness ta of the heat-adhesive polyolefin layers of both outer layers is 3 to 25, respectively.
μm, preferably 5 to 20 μm, more preferably 7 to
It is about 15 μm. Also, the thickness t of the polyamide intermediate layer
i imparts heat resistance to the film and the sealing material,
Often greater than the thickness of both outer layers. Therefore, the thickness ti of the intermediate layer can be selected according to the thicknesses of both outer layers within a range capable of imparting high heat resistance to the sealing material, for example, ti = 2.
× ta × 1.2 (μm) or more, preferably 2 × ta ×
1.5 ≦ ti ≦ 2 × ta × 5 (μm), and 2 ×
In many cases, it is about ta × 1.7 ≦ ti ≦ 2 × ta × 3 (μm). The thickness ti of the intermediate layer is usually 10 to 150.
μm, preferably 20 to 100 μm, and more preferably 30 to 80 μm.

The ratio (ti / t) of the thickness ti of the intermediate layer to the total thickness t of the film or the sealing material is 5
It is 0 to 95%, preferably 60 to 90%, more preferably 65 to 85%. When the ratio of the thickness of the outer layer (A layer) to the intermediate layer (B layer) is large, the heat resistance decreases,
If it is too small, the adhesion to the terminal board will decrease.

Since the film and the sealing material of the present invention have a layer structure composed of an outer layer containing a polyolefin having a low moisture permeability and a specific polyamide intermediate layer, they are highly moisture-proof. Further, since the outer layer and the intermediate layer are made of polyolefin and polyamide, which have high adhesiveness to each other, the adhesive strength between the A layer and the B layer is high even with a three-layer structure. Therefore, when the film and the sealing material are used, deterioration of the battery can be prevented for a long period of time.

In the film and the sealing material, the interlayer adhesive strength between the A layer and the B layer is 180 ° peel strength measured according to JIS K 6854, and is usually 700 g / 15 m.
m or more, preferably 1000 g / 15 mm or more, more preferably 2000 g / 15 mm or more in many cases. In some cases, the A layer and the B layer cannot be peeled off.

The moisture permeability of the film for sealing material and the sealing material, when measured according to ASTM F1249, is 60 g / m ² · day or less in terms of thickness of 25 μm (for example, 1
~ 50 g / m ² · day), preferably 52 g / m ² ·
Day or less (e.g., 1 to 50 g / m of about ² · day), more preferably not more than ² per day 47 g / m (e.g., 5～45G
/ M ² · day). When the moisture permeability of the sealing material is large,
The battery element is deteriorated by moisture and the battery life is shortened.

The film and sealing material of the present invention are
It suffices that it has at least the above-mentioned three-layer structure, that is, A layer and B
It may have a multilayer structure in which other layers such as an adhesive layer, a laminate layer, and a barrier layer are interposed between the layers. For example, when a vinylidene chloride-based polymer layer is formed between the A layer and the B layer, the moisture resistance can be further enhanced. It is possible to form a conductive metal layer between the A layer and the B layer, but this is not preferable because a short circuit may occur. When joining the A layer and the B layer with an adhesive or a laminating agent, the adhesive or the like may be corroded by the electrolytic solution of the battery depending on the thickness of the A layer (heat-adhesive polyolefin layer).

The film and the sealing material of the present invention have a heat-adhesive polyolefin layer (A layer) and a polyamide intermediate layer (B).
Layer) and the heat-adhesive polyolefin layer (A layer) are sequentially laminated to obtain a laminate having at least a three-layer structure. At that time, the intermediate layer may be formed of a resin composition containing the polyamide (1) or the polyamide (2) as a main component.

Preferred methods include a film forming method, particularly a melt forming method (for example, an extrusion forming method such as a T-die method and an inflation method) in order to improve the workability of lamination and the production efficiency of the sealing material. In the extrusion molding method, a dry laminating method using a laminating agent may be adopted, but in order to avoid erosion by an electrolytic solution, a thermal laminating method of sequentially laminating film-like melts without using a laminating agent, particularly The coextrusion method is preferred.

In the coextrusion molding method, the resin compositions corresponding to the A layer and the B layer are melted and kneaded by an extruder and merged in a die to have at least a three-layer structure (A layer / B).
Layer / A layer) in a molten state, and extruded from a die to form a film. The obtained film may be stretched, but in many cases, it is not stretched in order to prevent heat shrinkage during heat bonding. If necessary, the obtained film may be subjected to a surface treatment process such as corona discharge treatment.

The film thus obtained is often processed into a shape (for example, a frame shape) corresponding to the sealing material. The frame-shaped sealing material can be obtained by subjecting the film to a punching process or the like.

As described above, the sealing material obtained in this manner is a battery element (for example, a thin-walled terminal plate formed of a metal film or the like) interposed between a pair of terminal plates in a thin battery (for example, a thin terminal plate). , Positive electrode mixture, separator and negative electrode material). That is, a battery can be obtained by arranging a battery element between a pair of terminal plates, arranging a sealing material on a peripheral portion of the terminal plate, and thermally bonding an outer layer of the sealing material to the pair of terminal plates. it can.

The sealing material of the present invention has a small dimensional change in the width direction and the vertical direction even when subjected to thermal bonding. A thin battery using such a sealing material can suppress the exudation of the sealing material from the end surface. When mass-producing the thin battery, using a tape or film having a sealing portion corresponding to the sealing material at predetermined intervals, with the progress of the tape or film, sequentially arrange the terminal plate and the battery element, The outer layer of the sealing material is often heat-bonded. When the sealing material of the present invention is used, since the dimensional change is small as described above, the gap of the pitch of the sealing portion is small at the time of heat bonding, and the thin battery can be efficiently and accurately continuously manufactured. When used as such a sealing material, the pitch deviation of the sealing portion due to the thermal bonding is usually 8 mm or less, preferably 4 mm per 30 cm in the longitudinal direction (line direction).
It is about mm or less.

[0070]

Since the film for a sealing material of the present invention comprises both outer layers composed of a heat-adhesive polyolefin and an intermediate layer composed of a specific polyamide, it has any of moisture-proof property, adhesive property and heat resistance. Both properties are compatible and chemical resistance is high. Moreover, although both outer layers contain an olefin polymer, heat resistance can be improved. Therefore, when a sealing material formed of the film is used, a thin battery having high moisture resistance, chemical resistance, adhesiveness and heat resistance can be obtained.

[0071]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples.

Examples 1 to 8 The following A layer polymer and B layer polymer were each melted by an extruder and extruded from a T-die by a three-layer coextrusion molding method: A layer / B layer / A layer = 12/50/12 (μ
m) film (thickness: 74 μm) was obtained. The extrusion temperature is 220 to 250 ° C.

[Polymer for Layer A] (A1) Thermal Adhesive Polyethylene: Mitsui Petrochemical Co., Ltd.
Made by Admer NF550 (A2) heat adhesive polypropylene: Mitsui Petrochemical Co., Ltd.
Made by Admer QF550 (A3) heat adhesive polypropylene: made by Mitsubishi Kasei Co., Ltd.
Novatec AP030P [Polymer or resin composition for B layer] (B1) Polymethaxylylene adipamide (nylon MX
D6) (Mitsubishi Gas Chemical Co., Ltd., MX Nylon 600)
7) A mixture of 70 parts by weight and 30 parts by weight of nylon 12 (Daicel Huls Co., Ltd., Daiamide L1801F) (melting point: 240 ° C.) (B2) polymethaxylylene adipamide (nylon MS)
D6) (Mitsubishi Gas Chemical Co., Ltd., MS Nylon 600)
7) A mixture of 70 parts by weight and 30 parts by weight of nylon 6 (Ube nylon 1030B manufactured by Ube Industries, Ltd.) (melting point:
240 ° C) (B3) Nylon 12: manufactured by Daicel Huls Co., Ltd., Daiamide L1801F; melting point: 176 ° C) (B4) Nylon 12: manufactured by Daicel Huls Co., Ltd., Daiamide L2106F; melting point: 171 ° C (B5) Nylon 11: Toray Industries, Inc., Rilsan BES
NOTL; Melting point: 181 ° C. Comparative Examples 1 to 8 In place of the polymer for A layer, the polymer for B layer or the resin composition, the above polymer or the following polymer is used,
In the same manner as in Example 1, a single-layer or three-layer structure film (thickness: 74 μm) was obtained.

(C1) Nylon 6: manufactured by Ube Industries,
Ube Nylon 1030B; Melting Point: 225 ° C. (C2) Nylon 6/6: Ube Industries Ltd., Ube Nylon 2026B; Melting Point: 260 ° C. (C3) Adhesive Epoxy Resin: Ciba Geigy Ltd.
Araldite AW106 (main agent) and Araldite H
V9530 (curing agent) Then, a frame-shaped sealing material was prepared from the films obtained in the above-mentioned Examples and Comparative Examples, and a battery element composed of a positive electrode mixture material, a spacer and a negative electrode material was used as a positive / negative electrode terminal plate (SUS30).
4, a film having a thickness of 0.3 mm), heated and pressed at a temperature 30 ° C. higher than the softening point of the polymer for layer A, and a sealing material is heat-bonded to each of the terminal plates, so that a paper lithium battery (thickness: 0.5 mm x width 16.5 mm x length 3
4.5 mm) was produced.

When the following characteristics were evaluated, the results shown in the table were obtained.

[Vicat Softening Point] The Vicat softening point of the polymer of the layer A and the polymer or resin composition of the layer B is determined by JI.
In addition to the measurement according to SK 7206, the heat distortion temperature of the resin composition of layer B was measured according to JIS K 7207 with a load of 4.2 Kg / cm ² .

[Adhesive Strength] The adhesive strength (kg / 15 mm) between the sealing material and the terminal plate was measured as a 180 ° peel strength in accordance with JIS K 6854.

[Humidity resistance and chemical resistance] After being stored at 40 ° C. and 90% relative humidity (RH) for 40 days, the state of the adhesive surface, the electrolyte resistance of the sealing material and the battery performance (open circuit voltage, internal resistance and battery) The total height) was investigated.

[Heat Resistance] In order to evaluate heat resistance, the temperature at which the sealing material was melted and exuded from the battery was examined by applying a load of 5 kg / cm ² to the battery and raising the temperature.

[Moisture Proof] Moisture permeability of the films of Examples and Comparative Examples was measured by the method specified in ASTM F 1249, and converted into moisture permeability per 25 μm thickness. Also, B
The water vapor transmission rate of the polymer or resin composition constituting the layer was also measured in the same manner.

[0081]

[Table 1] As is clear from the table, the sealing materials of Examples have high moisture resistance, adhesiveness, chemical resistance and heat resistance.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a paper lithium battery which is an example of the present invention.

FIG. 2 is a schematic cross-sectional view of the sealing material shown in FIG.

[Explanation of Codes] 1, 6 ... Terminal plate 2 ... Positive electrode mixture material 3 ... Separator 4 ... Negative electrode material 5 ... Sealing material 11, 13 ... Thermal adhesive polyolefin layer 12 ... Intermediate layer

Claims (15)

[Claims] 1. A battery element interposed between a pair of terminal plates,
A film for a sealing material for sealing in the peripheral portion of the terminal plate, wherein the heat-adhesive polyolefin layers on both outer layers for thermally adhering to the pair of terminal plates, and these heat-adhesive polyolefin layers A film for a sealing material for a thin battery having at least a three-layer structure, which is formed by an intermediate layer composed of the polyamide of (1) or (2) below. (1) Aliphatic polyamide derived from lactam having 7 or more carbon atoms, aminocarboxylic acid, aliphatic diamine or aliphatic dicarboxylic acid (2) Polyamide having aromatic ring in main chain 2. The film for a sealing material according to claim 1, wherein the heat-bondable polyolefin has a heat-bonding strength of 1.5 kg / 15 mm or more with respect to the terminal plate. 3. The film for a sealing material according to claim 1, wherein the Vicat softening point of the heat-adhesive polyolefin is 120 ° C. or higher. 4. The film for a sealing material according to claim 1, wherein the heat-adhesive polyolefin is heat-adhesive polypropylene. 5. The aliphatic polyamide (1) constituting the intermediate layer is an aliphatic polyamide derived from a lactam having 10 to 14 carbon atoms, an aminocarboxylic acid, an aliphatic diamine or an aliphatic dicarboxylic acid. The film for a sealing material described. 6. The film for a sealing material according to claim 1, wherein the polyamide constituting the intermediate layer has a Vicat softening point higher by 10 ° C. or more than that of the heat-adhesive polyolefin. 7. The film for a sealing material according to claim 1, wherein the polyamide constituting the intermediate layer has a Vicat softening point of 145 ° C. or higher. 8. The moisture permeability of the polyamide constituting the B layer is
The film for a sealing material according to claim 1, which has a thickness of 25 g / m ² · day or less in terms of 25 μm. 9. The film for a sealing material according to claim 1, wherein the moisture permeability of the film is 60 g / m ² · day or less in terms of a thickness of 25 μm. 10. The heat-adhesive polyolefin layers on both outer layers have a thickness ta of 3 to 25 μm, respectively, and a thickness ti of the intermediate layer is ti = 2 × ta × 1.2 (μm) or more. The film for a sealing material according to 1. 11. The adhesive strength between the intermediate layer and the outer layer is 700.
The film for a sealing material according to claim 1, which has a g / 15 mm or more. 12. A film for a sealing material for sealing a battery element interposed between a pair of terminal plates at a peripheral portion of the terminal plate, wherein the thermal adhesion of both outer layers having a Vicat softening point of 125 ° C. or higher is modified. It is composed of a polyolefin layer (A) and an intermediate layer consisting of the polyamide of the following (1) or (2) interposed between these heat-adhesive modified polyolefin layers, and the film has a moisture permeability of 25 μm.
In terms of m, 52 g / m ² · day or less, and the moisture permeability of the polyamide forming the intermediate layer is 1 in terms of thickness of 25 μm.
05 g / m ² · day or less, and the ratio (ti / t) of the thickness ti of the intermediate layer to the thickness t of the entire film is 5
A film for a sealing material for thin batteries, which is 0 to 95%. (1) Nylon 11 or Nylon 12 (2) 35 mol% or more of m-xylylenediamine or p
-Polyamide derived from a diamine component containing xylylenediamine and a dicarboxylic acid component 13. A frame-shaped sealing material for sealing a battery element interposed between a pair of terminal plates at a peripheral edge portion of the terminal plates, which is the most suitable for thermally adhering to the pair of terminal plates. The heat-adhesive polyolefin layer as an outer layer and the heat-adhesive polyolefin layer interposed between the heat-adhesive polyolefin layer and the following (1)
Alternatively, a sealing material for a thin battery having at least a three-layer structure composed of the intermediate layer containing the polyamide of (2). (1) Aliphatic polyamide derived from lactam having 7 or more carbon atoms, aminocarboxylic acid, aliphatic diamine or aliphatic dicarboxylic acid (2) Polyamide having aromatic ring in main chain 14. A method for laminating a polyolefin layer having hot-melt adhesiveness, a polyamide intermediate layer, and a polyolefin layer having hot-melt adhesiveness, which comprises:
A method for producing a film for a sealing material, which comprises forming an intermediate layer using the resin composition containing the following (1) or (2) polyamide as a main component. (1) Polyamide derived from lactam having 7 or more carbon atoms, aminocarboxylic acid, diamine or dicarboxylic acid (2) Polyamide having aromatic ring in main chain 15. A battery element composed of a positive electrode mixture material, a separator and a negative electrode material, a pair of terminal plates for holding the battery element, and a battery element for sealing the battery element at a peripheral portion of the terminal plate. A thin battery comprising a sealing material, wherein the sealing material is composed of a laminated body having at least a three-layer structure including the following A layer and B layer. A layer: a heat-adhesive polyolefin layer constituting both outer layers B layer: an intermediate layer interposed between A layers, and (1) from a lactam having 7 or more carbon atoms, an aminocarboxylic acid, an aliphatic diamine or an aliphatic dicarboxylic acid Intermediate layer composed of a derived aliphatic polyamide or (2) a polyamide having an aromatic ring in the main chain