TW201518077A - Laminated body - Google Patents

Abstract

A laminated body includes: a substrate layer having a first surface and a second surface opposite to the first surface; a metal foil layer being provided so as to face the first surface of the substrate layer; a sealant layer facing a surface of the metal foil layer, the surface being on an opposite side of a surface of the metal foil layer facing the first surface; and a substrate protection layer having a water-soluble polymer and a hydroxyl group cross-linking agent, the substrate protection layer being provided on the second surface of the substrate layer.

Description

Laminated body

The present invention relates to a laminate.

As disclosed in Japanese Patent No. 3567229 (hereinafter referred to as Patent Document 1), a laminate having a base material layer formed of a nylon film and a coating layer formed on the base material layer is known. Outside. In the laminate described in Patent Document 1, the coating layer is selected from the group consisting of polydivinylidene chloride, vinylidene chloride-vinyl chloride copolymer, maleic anhydride modified polypropylene, polyester resin, and epoxy resin. At least one of a phenol resin, a fluororesin, a cellulose ester, an urethane resin, and an acrylic resin.

The laminate disclosed in Patent Document 1 is used as a covering material (exterior material) for a battery case that can be applied to a secondary battery or the like. The size of the secondary battery has been reduced due to the miniaturization of the portable device or the limitation of the installation space. Therefore, compared with the previous nickel-hydrogen or lead storage batteries, lithium ion batteries with high energy density have attracted attention in recent years.

In the case of an external material for a lithium ion battery, a material which is lightweight and highly heat-dissipating and can be formed by a multilayer film which is manufactured at low cost is widely used as compared with the metal can used previously. In the case of such an exterior material, for example, an exterior material is known which is a substrate layer/first bonding layer/aluminum foil layer/anti-corrosion treatment layer/second adhesion layer which prevents corrosion by hydrofluoric acid/ The sealant layer is laminated in sequence.

A lithium ion battery using such an exterior material has, for example, a concave portion formed by cold forming when a part of the exterior material is folded in half. Next, the contents of the battery such as the positive electrode, the spacer, the negative electrode, and the electrolytic solution are placed in the concave portion. The residual portion of the exterior material is heat sealed and sealed to seal the contents of the battery. In recent years, based on the purpose of efficiently accommodating more battery contents to increase energy density, a lithium ion battery has been proposed which forms recesses on both sides of the bonded exterior material.

To increase the energy density of a lithium ion battery, it is important to deepen the recess formed by cold forming and to increase the amount of battery contents contained in the recess. Therefore, a nylon film excellent in moldability is widely used in a substrate layer. However, since the nylon film has low durability to the electrolyte, when the lithium ion battery is manufactured or used, if the electrolyte adheres to the substrate layer, the substrate layer is dissolved, and the aluminum foil layer is corroded. Hey. Further, since the nylon film has low scratch resistance, the surface of the base material layer is scratched during the treatment, and the design property or strength is lowered.

The laminate described in Patent Document 1 can improve the durability of the electrolytic solution with respect to the substrate layer side. However, in the laminate described in Patent Document 1, it is difficult to obtain sufficient scratch resistance.

The present invention has been made in view of the above problems, and an object thereof is to provide a laminate which is excellent not only in moldability but also has high durability against electrolyte and high scratch resistance.

In order to solve the above problems, the present invention proposes the following method. A laminate according to an aspect of the invention has a substrate layer having a first surface and a second surface opposite to the first surface; a metal foil layer Provided to face the first surface of the substrate layer; a sealant layer facing the opposite side of the surface of the metal foil layer facing the first surface; and a substrate protective layer containing water solubility The polymer and the OH-based crosslinking agent are disposed on the second surface of the substrate layer.

Further, in the above aspect, the water-soluble polymer may be polyvinyl alcohol.

Further, in the above aspect, the substrate protective layer may have a thickness of 1 μm or more and 10 μm or less.

Further, in the above aspect, the OH-based crosslinking agent may be a polymer containing a maleic anhydride structure.

Further, in the above aspect, the concentration of the OH-based crosslinking agent may be 5% by mass or more and 40% by mass or less based on 100% by mass of the water-soluble polymer.

According to the above aspect, the laminate of the present invention is excellent not only in moldability but also in high durability against electrolyte and high scratch resistance.

10‧‧‧ Exterior materials

11‧‧‧Substrate layer

12‧‧‧1st bonding layer

13‧‧‧1st anti-corrosion treatment layer

14‧‧‧metal foil layer

15‧‧‧2nd anti-corrosion treatment layer

16‧‧‧2nd bonding layer

17‧‧‧Sealant layer

18‧‧‧Substrate protective layer

19‧‧‧ first side

20‧‧‧ second side

Fig. 1 is a cross-sectional view showing an example of a laminate of the present invention.

One embodiment of the laminated body of the present invention will be described below with reference to Fig. 1. In the present embodiment, an example of a laminate is described in the series of materials for lithium ion batteries. Fig. 1 is a cross-sectional view showing an embodiment of an exterior material 10 for a lithium ion battery, which is an example of a laminate of the present invention.

As shown in FIG. 1 , the exterior material 10 includes a base material layer 11 , a first adhesive layer 12 , a first anti-corrosion treatment layer 13 , a metal foil layer 14 , a second anti-corrosion treatment layer 15 , and a second adhesion layer 16 . The sealant layer 17 and the substrate protective layer 18. In the present embodiment, the exterior material 10 is based on the base material protective layer 18, the base material layer 11, the first adhesive layer 12, the first anticorrosive treatment layer 13, the metal foil layer 14, and the second anticorrosive treatment layer 15, The second adhesive layer 16 and the sealant layer 17 are laminated in this order.

The first adhesive layer 12 is laminated on the first surface 19 of the base material layer 11.

The first anticorrosive treatment layer 13 is laminated on the surface opposite to the surface of the base layer 11 which is laminated with the first adhesive layer 12.

The metal foil layer 14 is laminated on the surface of the first anti-corrosion treatment layer 13 opposite to the surface of the first adhesion layer 12.

The second anticorrosive treatment layer 15 is laminated on the surface opposite to the surface of the first anticorrosive treatment layer 13 which is laminated with the metal foil layer 14.

The second adhesive layer 16 is laminated on the surface opposite to the surface of the metal foil layer 14 which is laminated on the second anti-corrosion treatment layer 15.

The sealant layer 17 is laminated on the surface opposite to the surface of the second anticorrosive layer 15 on the surface of the second anticorrosive layer 15 .

The substrate protective layer 18 is laminated on the second surface 20 of the substrate layer 11.

The exterior material 10 is used in a state where the base material protective layer 18 is disposed outside and the sealant layer 17 is disposed inside.

The details of each laminate of the exterior material 10 will be described below.

(substrate protective layer)

The base material protective layer 18 can protect the base material layer 11 and suppress the deterioration or damage of the base material layer 11 by the electrolytic solution. The substrate protective layer 18 contains a water-soluble polymer. The water-soluble polymer is obtained by having durability against corrosion by hydrofluoric acid generated by hydrolysis reaction of a lithium salt such as LiPF ₆ or LiBF ₄ used in an electrolyte solution for a lithium ion battery due to moisture. Suitable for the softness of the outer shape of the formed battery. Examples of the water-soluble polymer include starch, protein, carboxymethylcellulose, sodium polyacrylate base, polyethylene oxide, polyvinylpyrrolidone, modified polyvinyl acetal, and polyvinyl alcohol. Further, the water-soluble polymer is preferably a polyvinyl alcohol which is extremely high in crystallinity and which can be obtained at low cost.

The degree of polymerization of the polyvinyl alcohol is preferably from 1,000 to 3,500, more preferably from 1,700 to 2,400. When the degree of polymerization of the polyvinyl alcohol is at least the lower limit (1000), the elongation is improved and the moldability is good. When the degree of polymerization of the polyvinyl alcohol is at most the upper limit (3,500) or less, the dispersibility of the filler or the pigment is excellent.

The degree of saponification of the polyvinyl alcohol is preferably 80 or more, more preferably 95 or more.

When the degree of saponification of the polyvinyl alcohol is at least the lower limit (80), the heat resistance and the water resistance are good. Further, when the degree of saponification of the polyvinyl alcohol is 95 or more, sufficient heat resistance and water resistance can be obtained even if high reliability such as vehicle load is required.

In the case of the degree of saponification of polyvinyl alcohol, if it is larger than the upper limit (99), it is generally difficult to synthesize and tends to be expensive, and on the other hand, since the performance cannot be expected to be improved, the upper limit (99) or less is desirable.

As the polyvinyl alcohol, a modified polyvinyl alcohol having a functional group such as a carboxyl group or a carbonyl group may also be used.

In the base material protective layer 18, in addition to the water-soluble polymer, by adding an OH-based crosslinking agent, it is possible to provide heat resistance required for thermal lamination when molding as a battery. It is considered that the molecules of the OH-based crosslinking agent of the linear molecular structure interact with each other to be a rigid crystal structure, thereby suppressing the excessive fluidity of the protective layer 18. Examples of the OH-based crosslinking agent include dialdehyde, glyoxal, a methylol compound, a phenol compound, and an isocyanate. Further, examples of the OH-based crosslinking agent include polyamidoamine epichlorohydrin, a vinyl hydrazine compound, an organometallic compound, and a vinyl ether-maleic anhydride copolymer. In the case of the OH-based crosslinking agent, polyammoniumamine epichlorohydrin is preferred, and vinyl ether-maleic anhydride copolymer is particularly preferred.

The concentration of the OH-based crosslinking agent is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less based on 100% by mass of the water-soluble polymer. When the concentration of the crosslinking agent is at least the lower limit (5% by mass), heat resistance required for heat-sealing the exterior material 10 can be obtained. When the concentration of the crosslinking agent is at most the upper limit (40% by mass), the filler dispersibility is good.

It is preferred that the substrate protective layer 18 may contain a slip additive or a slip additive to the surface of the substrate protective layer 18. Thereby, the moldability and the winding yield of the exterior material 10 are improved. Examples of the slip additive include fatty acid decylamine, glycerin, and the like. The fatty acid decylamine may, for example, be oleic acid amide, erucic acid amide, decylamine stearate, decyl phthalate, decyl phthalate, ethylene dans. Acid amide and the like. Further, the slip additive may be used singly or in combination of two or more.

The substrate protective layer 18 may contain an elastomer. Thereby, the moldability of the exterior material 10 is improved. Examples of the elastomer include a styrene type, an olefin type, an ester type, a soft vinyl chloride type, an urethane type, and a guanamine type.

The substrate protective layer 18 may also contain a plasticizer. Thereby, the moldability of the exterior material 10 is improved. The plasticizer may, for example, be dioctyl phthalate (DOP), dimethyl phthalate, diethyl phthalate, dipropyl phthalate or dibutyl phthalate. More specifically, dimethyl decanoate, diethyl decanoate, dibutyl phthalate, diisobutyl phthalate, octyl decanoate and the like can be mentioned. Further, examples of the phthalic acid plasticizer include dicyclohexyl phthalate, di-dodecyl phthalate, butyl benzyl phthalate, dimethyl glycol decanoate, and phthalyl phthalyl. Ethyl hydroxyacetate, etc. Further, examples of the phthalic acid plasticizer include methyl mercaptoacetate, butyl decyl glycolate, and diisononyl glycolate.

The diol-based plasticizer is preferably glycerin, but is not limited to glycerin. Examples of the diol-based plasticizer include ethylene glycol, diethylene glycol, triethylene glycol, and hexamethylene glycol. Further, examples of the diol-based plasticizer include polyethylene glycol, phthalyl glycolate, and triethylene glycol-2-ethylbutyrate. In the diol-based plasticizer, in addition to the above, a sugar alcohol such as sorbitol or xylitol or a compound thereof can be used as a plasticizer. In addition to the above, the diol-based plasticizer may be a polyester-based elastomer. The polyester elastomer includes a hard segment and a soft segment. As a hard segment, polypyridic acid A crystalline polyester such as butadiene ester, polybutylene naphthalate or polyethylene terephthalate. In the case of a polyester elastomer, polybutylene terephthalate is particularly preferred. Examples of the soft segment include polyoxyalkylene glycols such as polytetramethylene glycol, and polyesters such as polycaprolactone and polybutylene adipate. In terms of soft segments, it is particularly preferred to be polytetramethylene glycol.

The substrate protective layer 18 preferably contains one or more filler components selected from the group consisting of organic fillers and inorganic fillers. Thereby, the scratch resistance of the substrate protective layer 18 is improved. In the case of organic fillers, plastic powders or microparticles can be used. Examples of the plastics include acrylic acid, ethyl urethane, anthracene resin, polyethylene, polystyrene, polycarbonate, vinyl chloride, vinylidene chloride, and melamine. Examples of the inorganic filler include fine particles of carbon, cerium oxide, glass beads, glass frit, aluminum silicate, clay, zinc oxide, calcium carbonate, boron nitride, and mica.

In the substrate protective layer 18, it is preferable to contain a pigment in consideration of design. In the case of using a pigment, a pigment may be contained in any layer further than the metal foil layer 14. However, the base material protective layer 18 is excellent in pigment dispersibility and uniform in color, and it is preferable to contain a pigment in the base material protective layer 18.

The pigment is not particularly limited as long as it does not impair the adhesion between the substrate protective layer 18 and the substrate layer 11, and may be an organic pigment or an inorganic pigment. Examples of the organic pigment include an azo system, a phthalocyanine system, a quinacridone system, a lanthanide system, and a bismuth. Department, indigo, sulphur indigo, perinone-lanthanide, indolenine and the like. Examples of the inorganic pigment include a carbon black system, a titanium oxide system, a cadmium system, a lead system, and a chromium oxide system. Further, as the inorganic pigment, fine powder of mica, fish scale foil or the like can also be used.

The content of the water-soluble polymer in the substrate protective layer 18 (100% by mass) is excellent in durability against an electrolytic solution (hereinafter referred to as "electrolyte resistance"), and is excellent in scratch resistance. It is 30% by mass or more and 95% by mass or less, and more preferably 50% by mass or more and 90% by mass or less.

The content of the slip additive in the substrate protective layer 18 (100% by mass) is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more, in the case where the substrate protective layer 18 contains a slip additive. 5 mass% or less. The content of the slip additive in the base material protective layer 18 is more excellent as long as it is at least the lower limit (0.1% by mass). When the content of the slip additive in the base material protective layer 18 is equal to or less than the upper limit (10% by mass), the slip-slip additive can be prevented from oozing from the surface of the base material protective layer 18 facing the base material layer 11, and the base material layer 11 and the adhesion of the substrate protective layer 18 is reduced.

The content of the elastomer component in the substrate protective layer 18 (100% by mass) is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more, in the case where the substrate protective layer 18 contains an elastomer component. Below mass%. When the content of the elastomer component in the base material protective layer 18 is at most the upper limit (70% by mass), the scratch resistance or the electrolyte solution resistance is good.

The content of the plasticizer in the substrate protective layer 18 (100% by mass) is preferably 1% by mass or more and 60% by mass or less, and more preferably 10% by mass or more, in the case where the substrate protective layer 18 contains a plasticizer component. 50% by mass or less. When the content of the plasticizer in the base material protective layer 18 is at most the upper limit (60% by mass), the heat resistance is further improved.

The content of the filler component in the substrate protective layer 18 (100% by mass) is preferably in the case where the substrate protective layer 18 contains a filler component. 1% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 60% by mass or less. When the content of the filler component in the base material protective layer 18 is at least the lower limit (1% by mass), the scratch resistance is further improved. When the content of the filler component in the base material protective layer 18 is at most the upper limit (70% by mass), the moldability is further improved.

The content of the pigment in the base material protective layer 18 (100% by mass) is preferably 0.1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, in the case where the base material protective layer 18 contains a pigment. When the content of the pigment in the substrate protective layer 18 is less than the lower limit (0.1% by mass) or more and less than the upper limit (30% by mass), the design property is good.

The thickness of the base material protective layer 18 is preferably 1 μm or more and 10 μm or less, and more preferably 3 μm or more and 5 μm or less. When the thickness of the base material protective layer 18 is at least the lower limit (1 μm), the scratch resistance and the electrolytic solution resistance are further improved. When the thickness of the base material protective layer 18 is equal to or less than the upper limit (10 μm), the moldability is further improved.

(base material layer)

As the base material layer 11, for example, a nylon film or a polyester film can be used. It is especially good for nylon film. The nylon film may be an extended film or a non-stretch film. Examples of the nylon which forms the nylon film include, for example, nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 612, and the like. On the second surface 20 of the substrate layer 11, surface treatment such as corona treatment or plasma treatment is preferably performed. That is, in the nylon film forming the base material layer 11, it is preferred to subject the surface of the surface on which the substrate protective layer 18 is provided to a surface treatment such as corona treatment or plasma treatment. Thereby, the adhesion between the base material layer 11 and the base material protective layer 18 is further improved.

The thickness of the base material layer 11 is preferably 6 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less. When the thickness of the base material layer 11 is at least the lower limit (6 μm), pinhole resistance and insulation properties are further improved. When the thickness of the base material layer 11 is equal to or less than the upper limit (40 μm), the moldability is further improved.

A coupling agent may be applied to the surface of the base material layer 11 on which the first adhesive layer 12 is provided in order to improve the adhesion strength.

(1st bonding layer)

The first adhesive layer 12 is a layer of the bonded base material layer 11 and the first anti-corrosion treatment layer 13. The binder component constituting the first adhesive layer 12 is preferably a polyester polyol, a polyether polyol or the like. In addition, it is preferable that a two-functional or more aromatic or aliphatic isocyanate compound which is a curing agent acts on a two-liquid curing type of a main component such as an acrylic polyol, in order to form a binder component of the first adhesive layer 12 An urethane-based binder or the like. In the case where an urethane-based binder is used, it is possible to carry out the reaction of the hydroxyl group of the main component with the isocyanate group of the hardener after the coating, for example, by aging at 40 ° C for 4 days or more. Bonding. The thickness of the first adhesive layer 12 is preferably 1 μm or more and 10 μm or less, and more preferably 3 μm or more and 7 μm or less in consideration of adhesive strength, compliance, and workability.

(metal foil layer)

In the metal foil layer 14, various metal foils such as aluminum and stainless steel can be used, and aluminum foil is preferable from the viewpoints of workability and cost of moisture resistance and ductility. In the case of aluminum foil, a general soft aluminum foil can be used. In the case of the metal foil layer 14, the pinhole resistance and the extension during forming are considered. In terms of excellent properties, it is particularly good for aluminum foil containing iron. The iron content in the iron-containing aluminum foil (100% by mass) is preferably 0.1% by mass or more and 9.0% by mass or less, more preferably 0.5% by mass or more and 2.0% by mass or less. When the iron content is 0.1% by mass or more, the pinhole resistance and ductility of the exterior material 10 can be improved. As long as the iron content is 9.0% by mass or less, the flexibility of the exterior material 10 can be improved. The thickness of the metal foil layer 14 is preferably 9 μm or more and 200 μm or less, and more preferably 15 μm or more and 100 μm or less in terms of barrier properties, pinhole resistance, and workability.

(anti-corrosion treatment layer)

The first anti-corrosion treatment layer 13 and the second anti-corrosion treatment layer 15 can suppress the corrosion of the metal foil layer 14 by hydrofluoric acid caused by the reaction of the electrolytic solution or the electrolyte solution with water. Hydrogen fluoride is generated when a lithium salt such as LiPF ₆ or LiBF ₄ used in an electrolyte of a lithium ion battery is hydrolyzed by water. Therefore, the first anti-corrosion treatment layer 13 can suppress corrosion due to hydrofluoric acid inside the metal foil layer 14, and can suppress delamination between the layers inside the metal foil layer 14. Further, the second anticorrosive treatment layer 15 can achieve an effect of improving the adhesion between the metal foil layer 14 and the second adhesive layer 16. The first anticorrosive treatment layer 13 and the second anticorrosive treatment layer 15 are preferably a coating film formed by a coating type or a dipping type acid corrosion preventing treatment agent. The coating film-based metal foil layer 14 is excellent in corrosion resistance against acid. Further, since the coating film has a stronger adhesion between the metal foil layer 14 and the second adhesive layer 16 by the anchor effect, excellent resistance to the contents of the electrolytic solution or the like can be obtained.

The coating film may, for example, be oxidized by an anticorrosive treatment agent containing cerium oxide, phosphate, and various thermosetting resins. The coating film formed by the treatment of ceria sol or the like. In addition, a coating film formed by chromate treatment by an anticorrosive treatment agent containing chromate, phosphate, fluoride, and various thermosetting resins is exemplified. In addition, the first anticorrosive treatment layer 13 and the second anticorrosive treatment layer 15 are not limited to the above coating film as long as they are coating films capable of sufficiently obtaining the corrosion resistance of the metal foil layer 14. The first anticorrosive treatment layer 13 and the second anticorrosive treatment layer 15 may be, for example, a coating film formed by a phosphate treatment or a boehmite treatment.

The first anticorrosive treatment layer 13 and the second anticorrosive treatment layer 15 may be a single layer or a plurality of layers. Further, an additive such as a decane-based coupling agent may be added to the first anti-corrosion treatment layer 13 and the second anti-corrosion treatment layer 15. The thickness of the first anticorrosive treatment layer 13 and the second anticorrosive treatment layer 15 is preferably 10 nm or more and 5 μm or less, and more preferably 20 nm or more and 500 nm or less, from the viewpoint of the anticorrosion function and the fixing function.

(2nd bonding layer)

The second adhesive layer 16 is a layer of the metal foil layer 14 and the sealant layer 17 formed by bonding the second anti-corrosion treatment layer 15. The exterior material 10 is roughly divided into a thermal lamination structure and a dry lamination structure by forming the bonding component of the second bonding layer 16. In the heat-laminate structure, the adhesive component forming the second adhesive layer 16 is preferably an acid-modified polyolefin resin obtained by graft-modifying a polyolefin-based resin with an acid such as maleic anhydride. The production of the acid-modified polyolefin resin is carried out by introducing a polar group to a part of the non-polar polyolefin resin. In the acid-modified polyolefin resin, when the second anti-corrosion treatment layer 15 is a coating film having a polarity, the sealant layer 17 and the second anti-corrosion treatment layer 15 can be firmly adhered to each other. Also, acid modification The polyolefin resin can improve the resistance to contents such as an electrolytic solution, and even if hydrofluoric acid is generated inside the battery, the adhesion of the second adhesive layer 16 can be prevented from being lowered. The acid-modified polyolefin resin to be used in the second adhesive layer 16 may be one type or two or more types.

The polyolefin-based resin used for the acid-modified polyolefin resin may, for example, be a low-density, medium-density or high-density polyethylene; a vinyl ‧ α-olefin copolymer; a homogenous or block polymer; In addition, examples of the polyolefin-based resin used for the acid-modified polyolefin resin include atactic polypropylene, a propylene/α-olefin copolymer, and the like. In addition, as the polyolefin resin, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above copolymer, a polymer such as a crosslinked polyolefin, or the like can be used. The acid to be modified with the polyolefin resin may, for example, be a carboxylic acid, an epoxy compound or an acid anhydride, and particularly preferably maleic anhydride.

The binder component constituting the second adhesive layer 16 which is thermally laminated is preferably a maleic anhydride-modified polyolefin resin obtained by graft-modifying a polyolefin resin with maleic anhydride. Next, the copolymer component constituting the second adhesive layer 16 which is thermally laminated is particularly preferably a maleic anhydride-modified polypropylene. These are considered to be selected so as to easily maintain the adhesion between the sealant layer 17 and the metal foil layer 14 even if the electrolyte is infiltrated. The maleic anhydride-induced property of the maleic anhydride-modified polypropylene is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.3% by mass or more and 5% by mass or less. The modification ratio by the maleic anhydride of the maleic anhydride-modified polypropylene means the mass of the portion derived from maleic anhydride with respect to the total mass of the maleic anhydride-modified polypropylene.

The second adhesive layer 16 which is thermally laminated preferably contains an elastomer component described in the description of the substrate protective layer 18. In this way, the elastomer component is likely to be inhibited from being cracked and whitened in the second adhesive layer 16 during cold forming, and it is expected that the adhesion is improved due to the improvement in wettability, and the film formation property is improved due to the decrease in anisotropy. The elastomer component is preferably dispersed and miscible in a nanometer grade in the acid-modified polyolefin resin.

The second adhesive layer 16 which is thermally laminated can be formed by extruding the above-mentioned adhesive component by a pressing device. The melt flow rate (MFR) of the binder component of the second adhesive layer 16 which is thermally laminated is preferably 4 g/10 minutes or more and 30 g/10 minutes or less under conditions of 230 ° C and 2.16 kgf. The thickness of the second adhesive layer 16 which is thermally laminated is preferably 2 μm or more and 50 μm or less.

For the adhesive component of the second adhesive layer 16 which is formed by dry lamination, for example, a two-liquid curing type polyurethane adhesive which is the same as those exemplified in the first adhesive layer 12 can be mentioned. Since the second adhesive layer 16 having a dry laminated structure has a hydrolyzable joint portion such as an ester group or a urethane group, the second adhesive layer 16 having a thermal laminate structure is suitable for a purpose of achieving higher reliability.

(sealant layer)

The sealant layer 17 is a layer which provides a sealability due to heat sealing in the exterior material 10. The sealant layer 17 is a resin film formed of an acid-modified polyolefin resin obtained by graft-modifying an acid such as maleic anhydride with a polyolefin resin or a polyolefin resin. . Examples of the polyolefin-based resin include polyethylene having a low density, a medium density, or a high density; a vinyl ‧ α-olefin copolymer; a homopolymer, a block polymer, and the like.

Further, examples of the polyolefin resin include atactic polypropylene, a propylene/α-olefin copolymer, and the like. These polyolefin resins may be used alone or in combination of two or more. The acid-modified polyolefin-based resin may, for example, be the same resin as the resin exemplified for the second adhesive layer 16 .

The sealant layer 17 can be a single layer film or a multilayer film, and can be selected according to the necessary functions. As the sealant layer 17, for example, in order to provide moisture resistance, a multilayer film in which a resin such as an ethylene/cyclic olefin copolymer or polymethylpentene is interposed can be used.

As the sealant layer 17, when a film formed by extrusion molding is used, there is a tendency for molecules to be aligned in the extrusion direction of the film. Therefore, in the sealant layer 17, in order to alleviate the anisotropy caused by the alignment, the elastomer component described in the description of the substrate protective layer 18 may be blended. Thereby, the sealant layer 17 is hard to be whitened when the exterior material 10 is cold-formed to form a concave portion. Further, in the sealant layer 17, various additives such as a flame retardant, a slip additive, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier may be blended. The thickness of the sealant layer 17 is preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 60 μm or less.

The exterior material 10 may be an exterior material in which the sealant layer 17 is laminated by dry lamination. Moreover, in view of the improvement of the adhesiveness of the exterior material 10, it is preferable to laminate the sealant layer 17 by the sandwich-type lamination method which the acid-modified polyolefin resin of the 2nd adhesion layer 16 contains.

(Production method)

The manufacturing method of the exterior material 10 will be described below. However, the method of manufacturing the exterior material 10 is not limited to the following method. The method of producing the exterior material 10 may, for example, be a method having the following steps (1) to (4).

(1) A step of forming the first anti-corrosion treatment layer 13 and the second anti-corrosion treatment layer 15 on both surfaces of the metal foil layer 14.

(2) A step of laminating the base material layer 11 via the first adhesive layer 12 on the surface opposite to the surface of the first anti-corrosion treatment layer 13 on which the metal foil layer 14 is laminated.

(3) A step of laminating the base material protective layer 18 on the surface opposite to the surface of the base material layer 11 on which the first adhesive layer 12 is laminated.

(4) A step of laminating the sealant layer 17 via the second adhesive layer 16 on the surface opposite to the surface of the second anti-corrosion treatment layer 15 on which the metal foil layer 14 is laminated.

Details of each step will be described later.

step 1):

An anticorrosive treatment agent is applied to both surfaces of the metal foil layer 14 and dried to form a first anticorrosive treatment layer 13 and a second anticorrosive treatment layer 15. Examples of the anticorrosive treatment agent include an anticorrosive treatment agent for treating the above cerium oxide sol, an anticorrosive treatment agent for chromate treatment, and the like. The coating method of the anticorrosive treatment agent is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be employed.

Step (2):

The base material layer 11 is bonded to the surface on the opposite side to the surface of the first anti-corrosion treatment layer 13 on which the metal foil layer 14 is laminated, using a bonding agent forming the first adhesive layer 12, by dry lamination or the like. In the step (2), in order to promote the adhesion, the aging treatment may be performed in the range of from room temperature to 100 ° C.

Step (3):

A coating film containing a water-soluble polymer, an OH-based crosslinking agent, a slip-slip additive which can be used as needed, and an elastomer component, etc., on the side opposite to the surface of the base material layer 11 on which the first adhesive layer 12 is laminated The liquid is applied and dried to form a substrate protective layer 18. The solid content concentration of the coating liquid forming the substrate protective layer 18 is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less. When the solid content concentration is at least the lower limit (1% by mass), drying after application is easy. When the solid content concentration is at most the upper limit (20% by mass), the coating property is further improved.

Step (4):

In the case of the dry lamination configuration, the same binder as the binder forming the first binder layer 12 is used, and the surface of the second anticorrosion treatment layer 15 opposite to the surface on which the metal foil layer 14 is laminated is used. The sealant layer 17 is bonded to each other via the second adhesive layer 16. The bonding is performed by a method such as dry lamination, non-solvent lamination, or wet lamination. In the case of the thermal lamination, in the dry process, the bonding component of the thermal layer is used, and the surface of the second anti-corrosion treatment layer 15 opposite to the surface on which the metal foil layer 14 is laminated is extruded. The layer is legally formed to form the second stick Junction layer 16. Next, in the dry process, the sealant layer 17 is laminated by sandwich lamination. Further, in the wet process, the adhesive resin liquid in which the thermal layer bonding adhesive component is dispersed in the solvent is applied to the surface of the second anticorrosive treatment layer 15 opposite to the surface on which the metal foil layer 14 is laminated, to bond the components. The solvent is evaporated at a temperature above the melting point. Next, in the wet process, after the binder component is melted and softened and baked, the sealant layer 17 is laminated on the second binder layer 16 by heat treatment such as thermal lamination.

The exterior material 10 can be obtained by the steps (1) to (4) described above. Further, the method of manufacturing the exterior material 10 is not limited to the method of sequentially performing the above steps (1) to (4). For example, step (1) can be performed after performing step (2). Further, the step (3) can be carried out after the step (4) is carried out.

As described above, according to the exterior material 10 of the present embodiment, the substrate protective layer 18 containing the water-soluble polymer and the OH-based crosslinking agent is provided outside the base material layer 11. Therefore, the exterior material 10 has excellent electrolyte resistance and scratch resistance, and has sufficient moldability even when fine particles such as a filler or a pigment are added.

Further, according to the exterior material 10 of the present embodiment, since the water-soluble polymer is polyvinyl alcohol, the crystallinity is high and it can be obtained at low cost.

Further, according to the exterior material 10 of the present embodiment, since the thickness of the base material protective layer 18 is 1 μm or more and 10 μm or less, the scratch resistance and the electrolytic solution resistance can be improved, and the moldability can be improved.

Further, according to the exterior material 10 of the present embodiment, since the OH-based crosslinking agent contains a polymer having a maleic anhydride structure, the scratch resistance and the electrolytic solution resistance can be improved.

Further, according to the exterior material 10 of the present embodiment, the concentration of the OH-based crosslinking agent is 5% by mass or more and 40% by mass or less based on 100% by mass of the water-soluble polymer, so that the scratch resistance and the electrolyte resistance can be improved. .

[Examples]

The present invention will be described in detail by way of examples, but the invention is not limited by the description.

[Use materials]

The materials used in this embodiment are as follows.

(substrate protective layer 18)

Water-soluble polymer: polyvinyl alcohol (trade name "PVA124", manufactured by Kuraray Co., Ltd.)

OH-based crosslinking agent: vinyl ether-maleic anhydride copolymer (trade name "Gantrez AN-119", ISP Japan)

Filler: Acrylic beads having a particle size of 2.2 μm (trade name "J-4P", manufactured by K.K.) (base material layer 11)

Film (D): A nylon 6 film having a thickness of 25 μm.

(1st bonding layer 12)

Adhesive component (E): a urethane-based adhesive (trade name "A525/A50", manufactured by Mitsui Chemicals Polyurethane Co., Ltd.).

(metal foil layer 14)

Metal foil (F): Soft aluminum foil 8079 material (manufactured by Toyo Aluminum Co., Ltd., thickness: 40 μm).

(first anti-corrosion treatment layer 13 and second anti-corrosion treatment layer 15)

Treatment agent (G): "Sodium polyphosphate stabilized cerium oxide sol" adjusted to a solid concentration of 10% by mass using distilled water as a solvent. The phosphate was 10% by mass based on 100% by mass of cerium oxide.

(2nd bonding layer 16)

Bonding component (H): a polypropylene resin (trade name "Admer", manufactured by Mitsui Chemicals, Inc.) which is graft-modified with maleic anhydride.

(sealant layer 17)

Film (I): A corona-treated film which was to be the inner surface of a non-stretched polypropylene film (thickness 40 μm).

[Example 1]

The treatment agent (G) was applied to both surfaces of the metal foil (F) and dried, and the first anticorrosive treatment layer 13 and the second anticorrosion treatment layer 15 (thickness: 200 μm) were formed on both surfaces of the metal foil layer 14. Next, on the surface of the first anti-corrosion treatment layer 13 on the side opposite to the surface on which the metal foil layer 14 is laminated, the film (D) is bonded by a dry layer method using a bonding component (E). A bonding layer 12 (thickness: 4 μm) was laminated to laminate the substrate layer 11. Thereafter, aging was performed at 60 ° C for 6 days. Then, an OH-based crosslinking agent having a solid content concentration of 15% by mass based on the solid content of the water-soluble polymer was added to the aqueous solution of the water-soluble polymer (solid content: 10% by mass), and the mixture was stirred. Next, the obtained solution was applied to the surface of the base material layer 11 on the side opposite to the surface on which the first adhesive layer 12 was laminated by a gravure coating method, and dried to form a base material protective layer 18 (thickness: 3 μm). Thereafter, on the side of the second anticorrosive treatment layer 15 of the obtained laminate, the binder component (H) was pressed by a pressing device to form a second binder layer 16 (thickness: 50 μm). Next, the film (I) is bonded, and the sealant layer 17 is formed by sandwich lamination. Thereafter, the laminate was heated and pressed at 160 ° C, 4 kg/cm ² , and 2 m/min with respect to the obtained laminate to obtain an exterior material.

[Embodiment 2]

An exterior material was obtained in the same manner as in Example 1 except that a filler of 50% by mass with respect to the substrate protective layer 18 (100% by mass) was added to the substrate protective layer 18.

[Comparative Example 1]

An exterior material was obtained in the same manner as in Example 2 except that the thickness of the base material protective layer 18 was 0.5 μm.

[Comparative Example 2]

An exterior material was obtained in the same manner as in Example 2 except that the OH-based crosslinking agent was not added to the substrate protective layer 18.

[Comparative Example 3]

An exterior material was obtained in the same manner as in Example 2 except that the OH-based crosslinking agent of the substrate protective layer 18 was 50% by mass based on the solid content concentration of the water-soluble polymer.

[Comparative Example 4]

An exterior material was obtained in the same manner as in Example 1 except that the substrate protective layer 18 was not formed.

[Scratch resistance evaluation]

For the outer surface of the exterior material (the surface of the base material layer 11 or the substrate protective layer 18) obtained in Examples 1 to 2 and Comparative Examples 1 to 4, #0000 steel wool (manufactured by Nippon Steel Wool Co., Ltd.) was added. The load of 150 g/cm ² was rubbed back and forth 10 times. Next, on the outer surfaces of the exterior materials obtained in Examples 1 to 2 and Comparative Examples 1 to 4, the scratch depth was measured by a laser displacement meter. The evaluation of scratch resistance was carried out in accordance with the following criteria.

G (good): The surface scratch depth is less than 1 μm, and the scratch resistance is excellent.

P (poor): The surface scratch depth is 1 μm or more, and the scratch resistance is deteriorated.

[Evaluation of electrolyte resistance]

A few drops of the electrolytic solution were dropped on the outer surfaces of the exterior materials obtained in Examples 1 to 2 and Comparative Examples 1 to 4, and left in an environment of 25 ° C and 65% RH for 24 hours, and the electrolytic solution was wiped off to obtain an optical microscope (manufactured by Shimadzu Corporation). ) Confirm the deterioration of the surface. For a mixed solution of ethylene carbonate/dimethyl carbonate/diethyl carbonate = 1/1/1 (mass ratio), LiPF ₆ (lithium hexafluorophosphate) was dissolved and adjusted to 1.5 M to obtain an electrolytic solution. The evaluation of the electrolyte resistance was carried out in accordance with the following criteria.

G (good): No deterioration of the surface (whitening) was observed, and the durability to the electrolyte was excellent.

P (poor): deterioration of the surface (whitening) was observed, and the durability of the electrolyte was deteriorated.

[Evaluation of heat resistance]

The outer surfaces of the exterior materials obtained in Examples 1 to 2 and Comparative Examples 1 to 4 were heat-sealed for 10 seconds at a bar pressure of 0.2 MPa and a bar temperature of 200 degrees to visually confirm the surface. The evaluation was carried out in accordance with the following criteria.

G (good): It is impossible to observe melting or peeling on the surface, and it is excellent in heat resistance.

P (poor): Melt or peeling was observed on the surface, and heat resistance was deteriorated.

[Formability evaluation]

The exterior materials obtained in Examples 1 to 2 and Comparative Examples 1 to 4 were cut into blank test pieces of 150 mm × 190 mm, and cold molding was performed while changing the molding depth, and the moldability was evaluated. In the case of a punch, the shape is 100 mm × 150 mm, the punch angle R (RCP) is 1.5 mm, the punch shoulder R (RP) is 0.75 mm, and the die shoulder R (RD) is 0.75 mm. Punch machine. The evaluation was carried out in accordance with the following criteria.

E (excellent): It does not cause cracks or cracks, and it is possible to form deep drawing with a molding depth of 7 mm or more, and the moldability is excellent.

G (good): It is possible to form a depth of 5 mm or more and less than 7 mm in depth without cracking or cracking, and it is excellent in moldability.

P (poor): Due to the deep drawing of the molding depth of less than 5 mm, cracks and cracks are generated, and the moldability is deteriorated.

As is apparent from Table 1, Examples 1 and 2 in which a protective layer of a substrate to which a 15% by mass of an OH-based crosslinking agent with respect to a water-soluble polymer was added were formed, and sufficient scratch resistance was obtained regardless of the presence or absence of a filler. , electrolyte resistance, heat resistance and formability. In Comparative Example 1 in which the film thickness of the base material protective layer was reduced, the scratch resistance or the electrolytic solution resistance was lowered. Further, in Comparative Example 2 in which the OH-based crosslinking agent was not added to the substrate protective layer, resistance was not obtained. Heat. Further, in Comparative Example 3 in which a large amount of the OH-based crosslinking agent was added to the substrate protective layer, the dispersibility of the filler was lowered to affect the moldability. On the other hand, in Comparative Example 5 in which the protective layer of the substrate was not formed, scratch resistance or electrolytic solution resistance could not be obtained.

Further, the exterior material 10 of the present invention is not limited to the above. For example, other layers may be provided between any of the layers 18, 11, 12, 13, 14, 15, 16, 17 without departing from the effects of the present invention. Further, for example, the second anti-corrosion treatment layer 15 may be formed on the surface of the metal foil layer 14 close to the first adhesion layer 12.

Further, the exterior material 10 of the present invention may have other layers on the outer side of the substrate protective layer 18 within the range not impairing the effects of the present invention. In view of the fact that the exterior material 10 of the present invention has an effect of easily obtaining excellent scratch resistance and electrolyte resistance, the substrate protective layer containing a water-soluble polymer and an OH-based crosslinking agent is preferably the outermost layer. Further, in the case of the exterior material 10 of the present invention, it is preferable that the sealant layer 17 is on the outermost layer in view of the fact that the sealing property due to heat sealing can be obtained.

The lithium ion battery formed by the exterior material 10 of the present invention may, for example, be a lithium ion battery used for a portable terminal device such as a personal computer or a portable telephone, a camera, a satellite, an electric car, an electric bicycle, or the like. . In the lithium ion battery, the contents of the battery are housed in a container such as a bag-like material, and one of the tabs is placed at an external position and sealed. In terms of battery contents, it is a positive electrode, a separator, a negative electrode, an electrolyte, and a tab containing lead and a tab sealant. The lithium ion battery may be in a well-known form other than the exterior material 10 of the present invention.

10‧‧‧ Exterior materials

11‧‧‧Substrate layer

12‧‧‧1st bonding layer

13‧‧‧1st anti-corrosion treatment layer

14‧‧‧metal foil layer

15‧‧‧2nd anti-corrosion treatment layer

16‧‧‧2nd bonding layer

17‧‧‧Sealant layer

18‧‧‧Substrate protective layer

19‧‧‧ first side

20‧‧‧ second side

Claims (6)

A laminate comprising: a substrate layer having a first face and a second face opposite the first face; a metal foil layer disposed to face the first face of the substrate layer; sealing a layer of the metal foil layer facing away from the surface facing the first surface; the substrate protective layer comprising a water-soluble polymer and an OH-based crosslinking agent, and disposed on the substrate layer The second side. The laminate according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol. The laminate according to claim 1 or 2, wherein the substrate protective layer has a thickness of from 1 μm to 10 μm. The laminate according to claim 1, wherein the OH-based crosslinking agent comprises a polymer having a maleic anhydride structure. The laminate according to claim 2, wherein the OH-based crosslinking agent comprises a polymer of a maleic anhydride structure. The laminate according to any one of claims 1 to 5, wherein the concentration of the OH-based crosslinking agent is from 5% by mass to 40% by mass based on 100% by mass of the water-soluble polymer.