TW202015916A - Polyamide-based laminated film and method for producing same - Google Patents

Abstract

The object of the present invention is to provide a polyamide-based laminated film capable of exhibiting excellent electrolytic solution resistance in spite of the fact that the protective layer of the film is relatively thin. The present invention relates to a polyamide-based laminated film comprising a polyamide-based film substrate and a protective layer formed on at least one side of the substrate, wherein (1) the protective layer is in direct contact with the surface of the polyamide-based film substrate, (2) at least one of the protective layers is disposed as the outermost surface layer of the polyamide-based laminated film, (3) the protective layer comprises a copolymerized polyester resin in which a dicarboxylic acid component and a diol component are contained as constituent components, and in which a content of a dicarboxylic acid component having a naphthalene skeleton is 50 mol% or more in 100 mol% of structural units derived from dicarboxylic acid, and (4) the thickness of the protective layer is 1.5 [mu]m or less.

Description

Polyamide-based laminated film and manufacturing method thereof

Field of invention The invention relates to a polyamide-based laminated film for packaging or covering various products, especially electronic parts, electronics, other electronic devices and the like.

Background of the invention Conventionally, a laminated film containing a polyamide film has been used as an exterior material for batteries (lithium ion secondary batteries, etc.). As a representative example of the exterior material, a laminate in which polyamide film/aluminum foil/sealing layer is laminated in this order is known. In a lithium ion secondary battery using this laminate as an exterior material, the laminate is processed into a container shape such that the aforementioned polyamide film is disposed outside the battery and the sealing layer is disposed inside (inside the battery). Then, after packing the electrodes and the like inside the container, the electrolyte is injected.

When manufacturing such a lithium ion secondary battery, a step of injecting an electrolyte into the battery and a step of heat-sealing the exterior material after the injection are performed. In these steps, the electrolyte may splash and adhere to the polyamide film on the outside of the exterior material. Since the polyamide film has a low resistance to electrolyte (electrolyte resistance), when the polyamide film is disposed outside as in the aforementioned laminate, if the electrolyte adheres to the polyamide film, the film surface will be whitened. , Or a decomposition reaction occurs. As a result, the appearance of the product may be defective, the strength of the film may be reduced, and so on. Furthermore, when the electrolyte penetrates from the deteriorated portion of the polyamide film and contacts the aluminum foil, there is a possibility that the aluminum foil is corroded. In this case, it will cause the problem that the exterior material loses the required strength.

In order to solve the above problems, a method of providing a protective layer on the outer surface of the polyamide film has been proposed. For example, Patent Document 1 discloses an exterior material using polyethylene terephthalate as a protective layer. Patent Document 2 discloses an exterior material using a film that extends a laminate of a polyester film and a polyamide film. Patent Documents 3 to 5 disclose an exterior material in which a coating made of a specific resin is laminated as a protective layer on the outermost layer. Advanced technical literature Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2002-56824 Patent Literature 2: Japanese Patent Application Publication No. 2013-240938 Patent Document 3: Japanese Patent Laid-Open No. 2000-123799 Patent Document 4: Japanese Patent Application Publication No. 2014-176999 Patent Literature 5: Japanese Patent Application Publication No. 2014-176998

Summary of the invention Problems to be solved by the invention The exterior materials of Patent Documents 1 to 2 use a polyester film as a protective layer of a polyamide film. However, in addition to the step of providing an adhesive layer between the polyamide film and the polyester-based film, a separate step of laminating the polyester-based film is required, so the manufacturing process becomes complicated and the cost is also hindered reduce. In addition, since the total weight increases the weight of the adhesive, it is disadvantageous in terms of weight reduction of the battery.

The coating systems disclosed in Patent Documents 3 to 5 contain resin components such as polyvinylidene chloride and polyurethane. However, in order to give a sufficient protection function to the electrolyte, it is necessary to ensure a thickness of at least 1 μm or more as a protective layer. Therefore, in addition to the material cost of the protective layer itself becoming higher, the energy cost required for the drying step is also higher, which is economically disadvantageous. In addition, since the protective layer is formed by the post-coating method, in addition to an increase in the number of steps leading to an increase in cost, there is a possibility that the heat of the drying step adversely affects the physical properties of the substrate film.

Therefore, the main object of the present invention is to provide a polyamide-based laminated film that can exhibit excellent electrolyte resistance even if the protective layer is thin. Means to solve the problem

The present inventors have made continuous efforts to solve the above problems and found that by providing a protective layer containing a specific copolymerized polyester resin on the surface of the polyamide film, the above-mentioned object can be achieved and the present invention can be completed.

That is, the present invention relates to the following polyamide-based laminated film and its manufacturing method. 1. A polyamide-based laminated film comprising a polyamide-based film substrate and a protective layer formed on at least one side of the substrate, characterized in that: (1) The protective layer is formed by directly contacting the surface of the polyamide-based film substrate; (2) At least one protective layer is configured as the outermost layer of the polyamide-based laminated film; (3) The protective layer contains a copolymerized polyester resin containing a dicarboxylic acid component and a diol component as constituent components, and having a naphthalene skeleton in 100% of the structural units derived from the dicarboxylic acid The carboxylic acid content is more than 50 mole %; and (4) The thickness of the protective layer is 1.5 μm or less.

2. Polyamide-based laminated film as described in item 1 above, which satisfies the following general formula (1): (HzX)-(Hz0) <3.0 ... Formula (1) (However, the aforementioned Hz0 is based on the Japanese Industrial Standards " JIS K 7136” measured haze value, and the aforementioned HzX is the state where the electrolyte is attached to the protective layer after measuring the aforementioned Hz0, after maintaining at a temperature of 23°C and a humidity of 50%RH for 12 hours, in the same manner as Hz0 Measured haze value. The foregoing electrolyte solution was made by diluting LiPF ₆ to a concentration of 1 mole/mole in a mixed liquid composed of ethylene carbonate/diethyl carbonate/ethyl methyl carbonate=1/1/1 (volume ratio). L solution), and Hz0 is within the range of 10 or less.

3. The polyamide-based laminated film according to item 1, wherein the surface roughness (Ra) of the protective layer is 45 nm or less.

4. The polyamide-based laminated film as described in item 1, wherein the glass transition temperature of the copolymerized polyester resin is 60 to 145°C.

唑啉化合物中的至少1種。5. The polyimide-based laminated film according to item 1, wherein the protective layer further includes a melamine resin, an isocyanate compound, a carbodiimide compound, and

At least one of the oxazoline compounds.

6. The polyamide-based laminated film according to any one of items 1 to 5, which is laminated so that the protective layer directly contacts at least one side of the polyamide-based film base material, and is (a) A laminate including a protective layer, a polyamide-based film base material, a barrier layer, and a heat fusion layer in sequence, or (b) A laminate including a protective layer, a polyamide-based film base material, a protective layer, a barrier layer, and a heat welding layer in this order.

7. The polyamide-based laminated film according to any one of items 1 to 6, which is used for packaging articles.

8. A battery, including: Elements of power generation, including negative electrode, positive electrode, separator, and electrolyte; and Exterior materials used to package the power generation elements; its characteristics are: The aforementioned exterior material is the polyamide-based laminated film according to any one of items 1 to 5, and the protective layer is arranged as the outermost layer of the battery.

9. A method for manufacturing a polyamide-based laminated film, which is a method for manufacturing a polyamide-based laminated film according to any one of items 1 to 5 above, comprising: (1) A step of applying a coating liquid for forming a protective layer containing a copolymerized polyester resin to an unstretched polyamide-based film or a uniaxially stretched polyamide-based film, the copolymerized polyester resin containing a dicarboxylic acid component and The diol component is a constituent component, and the dicarboxylic acid component having a naphthalene skeleton in 100 mol% of the dicarboxylic acid component is 50 mol% or more; and (2) Extend the polyamide-based film having the coating film obtained by the aforementioned coating, thereby obtaining protection on one or both sides of the biaxially stretched film that has been extended in the MD and TD directions The layer of polyamide is the step of laminating the film. Invention effect

According to the present invention, a polyamide-based laminated film can be provided, which can exhibit excellent electrolyte resistance even when the protective layer is relatively thin.

In particular, since the protective layer of the polyamide-based laminated film of the present invention contains a copolymerized polyester resin having a dicarboxylic acid component having a naphthalene skeleton in an acid component of 50 mol% or more, even if the thickness of the protective layer is thin Less than 1.5μm, can still exert excellent electrolyte resistance. Therefore, even when the electrolyte is attached, the whitening and decomposition reaction of the polyamide-based film can be effectively suppressed. As a result, the strength of the polyamide-based laminated film can be maintained continuously.

In addition, since the surface roughness of the protective layer is relatively small (fewer irregularities), droplets are less likely to stay in the presence of the electrolyte. Therefore, it is possible to prevent the protective layer from being deteriorated due to long-term adhesion of the electrolyte.

Moreover, since the thickness of the protective layer is thin, it can be made thinner even with the polyamide-based laminated film, so even if it is coated in a state of being closely adhered to the packaged body, an excellent molded clothing can still be obtained Stickiness. Therefore, it is suitable to use a lithium ion secondary battery exterior material that requires adhesion or the like.

Since the thickness of the protective layer is as thin as 1.5 μm or less and can be easily formed under relatively mild heat treatment conditions, the influence on the physical properties of the polyamide-based film substrate can be minimized. This also contributes to the realization of a polyamide-based laminated film that combines excellent electrolyte resistance, mechanical properties, and anti-caking properties.

In particular, an electrolyte system used for a lithium ion secondary battery is prepared by dissolving an ionic substance in a polar solvent, and is a conductive liquid. As the ionic substance, lithium hexafluorophosphate (LiPF ₆ ) is generally used. If LiPF ₆ reacts with water, it will generate hydrofluoric acid (hydrogen fluoride) which is a strongly acidic medium. Therefore, when the electrolyte adheres to the air, the moisture in the air will react with LiPF ₆ in the electrolyte to generate hydrofluoric acid. Polyamide film used for exterior materials of lithium ion secondary batteries will be dissolved by the hydrofluoric acid. In contrast, the polyamide-based laminated film of the present invention has the specific protective layer as described above. Therefore, even if an electrolyte solution including LiPF ₆ or the like is attached, the polyamide film can maintain strength without deterioration.

In the manufacturing method of the present invention, since the protective layer can be formed by applying a specific protective layer forming coating liquid in an inline coat, it can be manufactured on the industrial scale and inexpensively as described above. Polyamide-based laminated film with excellent electrolyte properties. In particular, since the thickness of the protective layer can be as thin as 1.5 μm or less, it can be easily formed by in-line coating under relatively mild conditions. As a result, the influence on the physical properties of the polyamide-based film substrate and the like can be minimized. In this regard, it also contributes to the realization of a polyamide-based laminated film that combines excellent electrolyte resistance, mechanical properties, and anti-blocking properties.

Furthermore, in the manufacturing method of the present invention, since the protective layer can be formed by in-line coating of a specific coating liquid for forming a protective layer, the surface of the protective layer can be made flatter. This can also contribute to improving electrolyte resistance. Although the reason is not clear, it is speculated that it should be caused by the following mechanism of action. In the in-line coating method, the coating film obtained by the coating liquid for forming the protective layer is stretched and heat-treated together with the polyamide film, and by performing heat treatment while stretching, it can be formed mainly of a copolymerized polyester resin The high-density coating of the component smoothes the surface of the protective layer and can form a surface with less surface irregularities. As a result, it is presumed that since the surface of the protective layer is a surface with few irregularities, it is not easy to stay even if the electrolyte is attached, so that a protective layer having high protection performance against the electrolyte can be obtained.

The polyamide-based laminated film of the present invention having such characteristics is suitable for applications in which there is a possibility that an electrolyte (or acidic liquid) may adhere. In particular, it is suitably used, for example, as an exterior material for various batteries including lithium ion secondary batteries (especially laminated batteries).

1. Polyamide-based laminated film The polyamide-based laminated film of the present invention (the film of the present invention) includes a polyamide-based film base material and a protective layer formed on at least one side of the base material, and is characterized by: (1) The protective layer is formed by directly contacting the surface of the polyamide-based film substrate; (2) At least one protective layer is configured as the outermost layer of the polyamide-based laminated film; (3) The protective layer contains a copolymerized polyester resin containing a dicarboxylic acid component and a diol component as constituent components, and having a naphthalene skeleton in 100% of the structural units derived from the dicarboxylic acid The carboxylic acid component is more than 50 mole %; and (4) The thickness of the protective layer is 1.5 μm or less. A. Layer structure of the film of the present invention

As described above, the film of the present invention basically has a polyamide-based laminated film including a polyamide-based film substrate and a protective layer formed on at least one side of the substrate. That is, it is a layered body whose basic structure is such that the protective layer impermeable adhesive layer is formed so as to be adjacent to one side or both sides of the polyamide-based film base material.

FIG. 1 shows an example of the layer structure of the thin film of the present invention. FIG. 1A shows a laminated body (film of the present invention) 10 in which the protective layer 12 is laminated on one side of the polyamide-based film base material 11. Fig. 1B shows a layered product (film of the present invention) 10' in which the protective layers 12, 12 are laminated on both sides of the polyamide-based film substrate 11. In these cases, the protective layer in any case is configured as the outermost layer (outermost layer). In this way, by exposing the protective layer as the outermost layer, for example, when a package (bag, etc.) made of the film of the present invention is produced with the protective layer facing outward, the contents of the package can be protected from the outside.

In the film of the present invention, as long as the protective layer is formed directly on the polyamide-based film substrate and at least one protective layer is disposed as the outermost layer, other layers can be further laminated. For example, a barrier layer (gas barrier layer, water vapor barrier layer, etc.), a printed layer, a heat welding layer (adhesive layer, sealing layer, heat seal layer), primer layer (anchor coating layer), antistatic layer , Evaporation layer, ultraviolet absorption layer, ultraviolet blocking layer, etc.

FIG. 2 shows an example of a layer structure of a polyamide-based laminated film in which other arbitrary layers are further laminated in addition to the base of the polyamide-based film and the protective layer. FIG. 2A shows a laminated body 20 formed by further laminating a barrier layer 13 and a heat welding layer 14 in the laminated body 10 of FIG. 1A. Since this laminate 20 is an area layer barrier layer 13 and a heat welding layer 14 where the protective layer 12 is not formed on the polyamide-based film substrate 11, the state where the protective layer 12 is exposed as the outermost layer can be maintained. Fig. 2B shows a laminate 20' formed by further laminating the barrier layer 13 and the heat welding layer 14 in the laminate 10' of Fig. 1B in this order. Although this laminate 20' has the barrier layer 13 and the heat welding layer 14 laminated on either of the protective layers 12 of the polyamide-based film substrate 11, the state in which the other protective layer 12 is exposed as the outermost layer can be maintained. In addition, as shown in FIG. 2, in the case where the film of the present invention has a heat welding layer, the heat welding layer is arranged as the outermost layer.

Hereinafter, in addition to the polyamide-based film base material and the protective layer constituting the film of the present invention, arbitrary layers will be described separately. A-1. Polyamide-based film substrate

The polyamide-based film base material constitutes the base material (core material) of the film of the present invention, and is usually provided in the form of a pre-formed film. The polyamide-based film substrate may have a single-layer structure or a multilayer structure in which two or more polyamide-based films are laminated. In addition, in the case of a multilayer structure, each layer may have the same composition as each other, or may have a different composition.

The polyamide-based film base material mainly contains a polyamide-based resin, but may contain other components. In this case, the content ratio of the polyamide resin in the polyamide resin base material is not limited, but it is usually 70 to 100% by mass, particularly preferably 90 to 99.5% by mass.

The polyamide resin may be a melt-moldable thermoplastic resin having an amide bond (-CONH-) in its molecule, and known or commercially available resins can be used. Therefore, for example, polyamides obtained by polycondensation of internal amides, ω-amino acids, or dibasic acids and diamines can be mentioned.

Examples of the internal amides include ε-caprolactam, enantholamide, capryl lactam, and lauryl amide.

Examples of ω-amino acids include 6-aminohexanoic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, and 11-aminoundecanoic acid.

Examples of the dibasic acids include adipic acid, glutaric acid, pimelic acid, suppository acid, azalea acid, lipoic acid, undecanedioic acid, dodecanedioic acid, hexadecanedioic acid, Alkanedioic acid, eicosadienedioic acid, 2,2,4-trimethyladipic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, xylylene dicarboxylic acid Carboxylic acid etc.

Examples of the diamines include ethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, nonamethylene diamine, decamethylene Diamine, undecylmethylenediamine, 2,2,4 (or 2,4,4)-trimethylhexamethylenediamine, cyclohexanediamine, bis-(4,4'-amine Cyclohexyl) methane, m-xylylenediamine, etc.

For the polymers or copolymers obtained by polycondensation, for example, nylon 6, 7, 11, 12, 6.6, 6.9, 6.11, 6.12, 6T, 9T, 10T, 6I, MXD6 (polym-xylylene Hexamethylenediamide), 6/6.6, 6/12, 6/6T, 6/6I, 6/MXD6, etc. These can be used alone or in combination of two or more. From the viewpoint of excellent balance between heat resistance and mechanical properties, among these, the polyamide resin is preferably made of nylon 6.

In addition, the relative viscosity of the polyamide-based resin used as the substrate of the polyamide-based film is not particularly limited, but it is usually about 1.5 to 5.0, and particularly preferably 2.0 to 4.0. If the relative viscosity of the polyamide is less than 1.5, there is a concern that the mechanical properties of the resulting film are likely to be significantly reduced. On the other hand, if the relative viscosity exceeds 5.0, the film forming properties of the film are likely to be hindered. In addition, the above-mentioned relative viscosity is the value obtained by measuring the sample solution (liquid temperature 25 degreeC) which melt|dissolved the polyamide in 96% sulfuric acid to a concentration of 1.0 g/dl using a Ubbelohde viscometer.

As described above, the polyamide-based film base material system may contain other components in addition to the polyamide-based resin within a range that does not hinder the effects of the present invention. Other ingredients may include known or commercially available additives. More specifically, examples include metals (metal ions), pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, mold release agents, and strengthening agents (fillers). In particular, as the heat stabilizer or antioxidant, hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like are suitably used.

In addition, in order to improve the slip properties of the film and the like, it is preferable to contain at least one kind of inorganic lubricant or organic lubricant in a range satisfying the surface roughness (Ra) of 45 nm or less. Specific examples of the lubricant include clay, talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, magnesium aluminosilicate, Inorganic lubricants such as glass balloon, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, layered silicate, etc.; amide erucate, amide oleate, amide stearate, Ethylene bisstearate amide, ethylene bisethylene bis oleate amide, hexamethylene bis stearate amide, hexamethylene bis oleate amide methylene bis stearate Organic lubricants such as amide.

The thickness of the polyamide-based film substrate is not particularly limited, but it is usually preferably 4 to 30 μm, and particularly preferably 5 to 25 μm. If the thickness is less than 4 μm, the mechanical strength is likely to be insufficient, and the formability will be reduced. On the other hand, if the thickness exceeds 30 μm, the weight increases, and it becomes difficult to use it for applications in which weight reduction is desired. If the mechanical strength is sufficient, a thinner layer can enclose more electrolyte, so it is preferable from the viewpoint of ensuring the amount of content or capacitance.

In addition, from the viewpoint of mechanical strength, the polyamide-based film substrate is preferably stretched. That is, it is better to have a structure with alignment. In this case, it may be uniaxial extension or biaxial extension, but it is particularly preferable to have the alignment obtained by biaxial extension. The extension ratio can be appropriately set within the range described below.

In order to improve the adhesion between the layers constituting the laminate when forming the laminate, it is preferable to have a surface that is subjected to known surface treatments such as corona treatment, plasma treatment, and ozone treatment on at least one side. . In particular, the surface roughness is preferably 10 nm or more. In addition, from the viewpoints of electrolyte resistance and improvement of blocking resistance, the surface roughness of the protective layer is preferably the same or higher. That is, in the present invention, "the surface roughness of the protective layer ≦ the surface roughness of the polyamide base film" is preferable. A-2. Protective layer

The protective layer contains a copolymerized polyester resin containing a dicarboxylic acid component and a glycol component as constituent components, and having a naphthalene skeleton in 100% of the structural units derived from the dicarboxylic acid The carboxylic acid component is 50 mol% or more (hereinafter, this specific copolymerized polyester resin is referred to as "copolymerized polyester resin A"). Therefore, for such a copolymerized polyester resin A, for example, a copolymer obtained by subjecting the above dicarboxylic acid component and diol component to polycondensation reaction is suitable. (a) Copolymer polyester resin A Dicarboxylic acid component

The dicarboxylic acid component is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 4,4'-dicarboxybiphenyl, phenyldicarboxylic acid, diphenylsulfodicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfodicarboxylic acid and other aromatic dicarboxylic acids; Oxalic acid, malonic acid, succinic acid, adipic acid, glutaric acid, lipoic acid, undecanedioic acid, dodecanedioic acid, octadecanedioic acid, dimer acid, maleic acid, fumaric acid , Iconic acid, citraconic acid and other aliphatic dicarboxylic acids; 1,4-cyclohexane dicarboxylic acid and other alicyclic dicarboxylic acids; p-hydroxybenzoic acid and other hydroxycarboxylic acids. One or more of these can be used.

Among them, the dicarboxylic acid component having a naphthalene skeleton (hereinafter also referred to as "dicarboxylic acid component A") includes, for example, 2,6-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, and 2,3-naphthalene Dicarboxylic acid and so on. Among them, 2,6-naphthalene dicarboxylic acid is particularly preferred from the viewpoint of small steric hindrance and high crystallinity in the present invention.

Then, in the present invention, the dicarboxylic acid component A usually contains 50 mol% or more in the structural unit (100 mol%) derived from the dicarboxylic acid component, and particularly preferably contains 60 mol% or more. The content of 70 mol% or more is preferable, and the content of 80 mol% or more is most preferable. This can ensure higher electrolyte resistance. The upper limit of the content of the dicarboxylic acid component is not particularly limited, but it can usually be about 95 mol%.

In this case, the content of the dicarboxylic acid component other than the dicarboxylic acid component A (hereinafter referred to as "dicarboxylic acid component B") is not particularly limited, and the structural units derived from the dicarboxylic acid component (100 mol% ) Usually contains about 1 to 50 mol%, especially 5 to 45 mol%.

In the present invention, the use of terephthalic acid is particularly preferred for the dicarboxylic acid component B from the viewpoint of small steric hindrance and high crystallinity. In the case where terephthalic acid is included, the content of terephthalic acid in the structural unit (100 mol%) derived from the dicarboxylic acid component is not particularly limited, and is usually about 3 to 50 mol%, especially Containing 5 to 45 mol% is preferable, and containing 10 to 40 mol% is the best. Therefore, in the present invention, as the dicarboxylic acid component, a composition containing 2,6-naphthalene dicarboxylic acid and terephthalic acid is suitably used. More specifically, the structural unit derived from the dicarboxylic acid component (100 mol%) contains 50 mol% or more in the structural unit derived from the dicarboxylic acid component (100 mol%) , 6-naphthalene dicarboxylic acid and 5 mol% of terephthalic acid composition. Therefore, for example, in the structural unit derived from the dicarboxylic acid component (100 mol%), the structural unit derived from the dicarboxylic acid component (100 mol%) may contain more than 55 to 90 mol% 2 , 6-naphthalene dicarboxylic acid and 5 to 45 mol% of terephthalic acid composition.

In addition, in the present invention, the dicarboxylic acid component B may contain aliphatic dicarboxylic acids such as adipic acid, lipoic acid, etc. However, if these contents are increased, there is a possibility that the electrolyte resistance of the protective layer may be reduced Therefore, the content of the aliphatic dicarboxylic acid is preferably 20 mol% or less in the structural unit derived from the dicarboxylic acid (100 mol%), especially 15 mol% or less, of which 5 mol% The following is the best.

In addition, when the dicarboxylic acid component B is used, the blending ratio (molar ratio) of the dicarboxylic acid component A and the dicarboxylic acid component B is usually about 50:50 to 98:2, and particularly preferably 80: 20 to 95: 5 or so. Glycol component

The glycol component is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1 , 5-pentanediol, 1,6-hexanediol, neopentyl glycol and other aliphatic dihydroxy compounds; diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Alcohol; cycloaliphatic dihydroxy compounds such as 1,4-cyclohexanedimethanol and spirodiol; aromatic dihydroxy compounds such as bisphenol A. One or more of these can be used.

From the viewpoint of enhancing electrolyte resistance, among these, an aliphatic dihydroxy compound is preferred, and an aliphatic dihydroxy compound containing 4 or less carbon atoms is preferred. More specifically, at least one of ethylene glycol, diethylene glycol, 1,2-propanediol, and 1,3-propanediol can be mentioned.

The aliphatic dihydroxy compound is usually preferably contained in a structural unit derived from a diol component (100 mol %) of 50 mol% or more, particularly preferably 60 mol% or more, and 70 mol% or more For better, more than 80 mol% is the best. The upper limit of this content may be 100 mol%, for example, but it is not limited thereto.

In addition, in the present invention, aliphatic diols having a carbon number of 5 or more, such as 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol, may also be contained, but the content is too high The electrolyte resistance is easily reduced, so the content of the aliphatic diol having a carbon number of 5 or more is preferably about 0 to 25 mol% in 100 mol% of structural units derived from the diol component. Other copolymer components

When the copolymerized polyester resin A is a coating liquid for forming an aqueous protective layer, the dicarboxylic acid component B preferably contains a dicarboxylic acid component having a sulfonic acid group (-SO ₃ H), especially a sulfonic acid group The aromatic dicarboxylic acid is preferred). For example, 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, sulfoterephthalic acid, and 4-sulfonaphthalene-2,6 -At least one kind of dicarboxylic acid is preferable, and 5-sulfoisophthalic acid is particularly preferable in terms of cost. That is, a dicarboxylic acid component having no naphthalene skeleton and having a sulfonic acid group is suitably used as the dicarboxylic acid component B. In addition, in the case of compounds that belong to both dicarboxylic acids A and B, the content of the compound can also be calculated as dicarboxylic acid B.

The content of the dicarboxylic acid component having a sulfonic acid group is preferably 3.5 to 30 mol% in 100 mol% of the structural units derived from the dicarboxylic acid component, of which 4 to 20 mol% is preferred, and 4 to 10 mol% is particularly preferred. Physical properties of copolymerized polyester resin A

The glass transition temperature of the copolymerized polyester resin A is preferably 60°C or higher, particularly preferably 80°C or higher, and 100°C or higher is the most preferable. When the glass transition temperature does not reach 60°C, the binding force between the molecular chains constituting the copolymerized polyester resin becomes weak, so the electrolyte resistance may be poor.

On the other hand, as will be described later, the film of the present invention is preferably produced by applying a coating solution for forming a protective layer to a polyamide film that has not been stretched or uniaxially stretched, and then performing stretching, but If the glass transition temperature of the copolymerized polyester resin A becomes higher, the stretchability with the polyamide film will decrease, and the film will be easily cut. Therefore, the glass transition temperature is preferably 145°C or lower, of which 140 Below ℃ is preferred.

唑啉化合物中的至少1種為佳。此等可使用已知物或市售物。In addition, the copolymerized polyester resin A may have a cross-linked structure. For example, the cross-linked structure can be formed by using a cross-linking agent that reacts with the carboxyl group or hydroxyl group of the terminal group of the copolymerized polyester resin A. As a result, excellent electrolyte resistance, physical properties, etc. can be exhibited. The crosslinking agent is not particularly limited as long as it can carry out the above reaction, but it may include a melamine resin, an isocyanate compound, a carbodiimide compound,

At least one of the oxazoline compounds is preferred. For these, known products or commercially available products can be used.

The crosslinking agent preferably contains 0.1 to 15% by mass in the protective layer, particularly preferably contains 0.1 to 10% by mass, and preferably contains 2.5 to 7.5% by mass. By setting within such a range, more excellent electrolyte resistance can be obtained. Synthesis of Copolyester Resin A

The copolymerized polyester resin A can basically be synthesized according to a known method for producing a copolymerized polyester resin, except that the specific dicarboxylic acid component and diol component as described above are used. That is, it is suitable to manufacture the copolymerized polyester resin A by a manufacturing method including the step of including 50 mol% or more of the dicarboxylic acid component having a naphthalene skeleton in 100 mol% of the dicarboxylic acid component. The carboxylic acid component and the diol component undergo a polycondensation reaction.

In addition to the dicarboxylic acid exemplified above, at least one kind of derivatives such as metal salts, acid anhydrides, and ester compounds thereof can be used as the dicarboxylic acid component (dicarboxylic acid compound). These compounds themselves can be the same compounds used in the synthesis of known copolyester resins.

As the diol component (diol compound), in addition to the glycols exemplified above, at least one kind of derivatives such as metal salts, acid anhydrides, and ester compounds thereof can be used. These compounds themselves may be the same compounds used in the synthesis of known copolyester resins.

The mixing ratio of the carboxylic acid component and the diol component can be appropriately set within a range in which the polycondensation reaction can be sufficiently carried out. Usually, it is sufficient to set the molar ratio to the range of the carboxylic acid component: diol component=1: 0.5 to 1.5 , But not limited to this.

In addition, polymerization catalysts can also be added to the raw materials as needed. The polymerization catalyst is not limited, and known catalysts can be used, and titanium-based catalysts such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate are suitably used. The addition amount of the polymerization catalyst is not particularly limited, and it can usually be appropriately adjusted within a range of 5×10 ^-5 to 5×10 ^-4 moles relative to 1 mole of carboxylic acid component.

The reaction system only needs to be a liquid phase reaction. Since the diol component is usually in a liquid state, the reaction can be carried out without a solvent. Organic solvents can be used as needed. In addition, the pressure of the reaction gas environment may be normal pressure, reduced pressure (including vacuum), or under pressure. Generally, the ambient gas may be in an inert gas environment such as nitrogen or argon.

The reaction system is preferably carried out in two stages, which includes the transesterification reaction step in the first stage; and the polymerization reaction step in the second stage.

The reaction temperature in the transesterification reaction step is not particularly limited as long as each component can be melted, and it can generally be set at about 200 to 260°C. The reaction time depends on the reaction temperature and the like, and it is usually in the range of about 1 to 5 hours.

The reaction temperature in the polymerization reaction step is not particularly limited as long as the polymerization of the initial condensate (ester compound) can be carried out, and it can generally be set at about 200 to 260°C. The reaction time depends on the reaction temperature and the like, and it is usually in the range of about 1 to 5 hours. In particular, in the polymerization reaction step, it is preferably carried out under reduced pressure or under vacuum, more specifically about 1×10 ⁻⁵ to about 1×10 Pa. Therefore, it may be set to, for example, about 1×10 ^-4 to 1×5 Pa, or may be set to about 1×10 ^-5 to 1×10 ^-1 Pa.

Since the obtained reaction product is usually liquid at ordinary temperature and pressure, it can be directly used as a raw material of a coating agent for forming a protective layer. According to requirements, the liquid reaction product can also be subjected to solid-liquid separation, purification and other treatments before separation. In this way, copolymerized polyester resin A can be obtained.

唑啉中的至少1種，尤以

唑啉為佳。In addition, in the present invention, in order to make the copolymerized polyester resin A have a cross-linked structure as necessary, the copolymerized polyester resin A may be further reacted with a cross-linking agent. In the case where a crosslinking agent is included, by reacting with either or both of the carboxyl group or hydroxyl group of the terminal group of the copolymerized polyester resin, the crosslinking density of the protective layer becomes higher, so that the electrolyte resistance of the protective layer can be further improved performance. Then, when the in-line coating method is used, the electrolyte resistance of the protective layer is improved by the cross-linking agent like this, and the effect is more significant for the blocked isocyanate and

At least one of the oxazolines, especially

Oxazoline is preferred.

The addition amount of the crosslinking agent may be as long as it contains a specific ratio in the protective layer as described above. For example, it can be appropriately adjusted within a range of 1 to 15 parts by mass relative to 100 parts by mass of the copolymerized polyester resin A. When adding the crosslinking agent, it is sufficient to add and mix the crosslinking agent to the copolymerized polyester resin A and maintain it for a certain period of time. In this case, the maintenance temperature is not particularly limited, and it is usually only 5 to 30°C. The maintenance time is usually from 0 to 120 hours. (b) Composition and physical properties of the protective layer

As described above, the protective layer contains the copolymerized polyester resin A, and the content of the copolymerized polyester resin A in the protective layer is preferably 70 to 100% by mass, particularly preferably 80 to 95% by mass.

Therefore, the protective layer may contain components other than the copolymerized polyester resin A within a range that does not hinder the effect of the present invention. Various additives such as lubricants, heat stabilizers, antioxidants, reinforcing materials (fillers), pigments, anti-deterioration agents, weathering agents, flame retardants, plasticizers, mold release agents, cross-linking agents, etc. may be mentioned. For these, the same additives as those suitable for the aforementioned polyamide-based film substrate can be used.

In particular, the lubricant includes organic lubricants such as ethylenebisstearate, organic particles such as acrylic particles, and inorganic particles such as silica. Since these can also function as an anti-caking agent, it is preferable to add one or more of the above lubricants.

In addition, examples of the heat stabilizer, antioxidant, and anti-deterioration agent include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, or mixtures thereof.

Examples of reinforcing materials include clay, talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass hollow sphere , Carbon black, zinc oxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate whisker, boron nitride, graphite, glass fiber, carbon fiber, etc. One or more of these can be added.

From the viewpoint of further improving electrolyte resistance, the inorganic layered compound may be contained. The inorganic layered compound is an inorganic compound in which unit crystal layers overlap to form a layered structure, and specific examples include zirconium phosphate (phosphate derivative compound), chalcogenide, lithium aluminum composite hydroxide, graphite, clay mineral, etc. , Especially those that swell or crack in the solvent.

The thickness of the protective layer needs to be 1.5 μm or less, particularly preferably 1 μm or less from the viewpoint of shortening the drying time to improve productivity and anti-blocking properties. A protective layer with a thickness exceeding 1.5 μm may cause unevenness in the formation step or drying step of the electrolyte-resistant protective layer, or the productivity may be reduced due to the longer heating time, or the cost of the coating liquid may increase Lack of advantages, and poor resistance to caking.

On the other hand, regarding the lower limit of the thickness of the protective layer, in order to sufficiently improve the resistance to acidic liquids such as an electrolyte, the thickness of the protective layer is preferably 0.05 μm or more, particularly preferably 0.1 μm or more, and 0.2 μm or more. Preferably, 0.4 μm or more is the best.

The surface roughness Ra of the protective layer (exposed surface) is not particularly limited. From the viewpoint of improving electrolyte resistance, 45 nm or less is preferable, 40 nm or less is particularly preferable, and 35 nm or less is most preferable. If the surface roughness of the protective layer exceeds 45 nm, the electrolyte may easily remain on the protective layer and the electrolyte resistance may be impaired. The lower limit value of the surface roughness Ra may be, for example, 20 nm or 15 nm, but is not limited thereto. In addition, the surface roughness can be controlled to 45 nm or less by, for example, forming a protective layer by an in-line coating method using a predetermined coating liquid for forming a protective layer as described later. A-3. Other layers

As mentioned above, in addition to the polyamide-based film substrate and the protective layer, the film of the present invention can also be laminated with various layers as required. Each layer itself may use the same layer as that used in known packaging materials and the like. The film of the present invention is shown in FIG. 2, for example, a laminate composed of a protective layer/polyamide-based film base material/barrier layer/heat fusion layer, a protective layer/polyamide-based film base material/protective layer/barrier layer /Laminates composed of thermally welded layers can be used as effective battery exterior materials. Here, a suitable embodiment of the barrier layer and the heat welding layer will be described. Barrier layer

The barrier layer only needs to be a barrier layer that can exhibit gas barrier properties (oxygen barrier properties) and water vapor barrier properties. For example, a known layer or a commercially available barrier layer or film such as a metal foil or a vapor-deposited film can be used. Among them, the metal foil with a wide range of uses is preferred. The metal foil is preferably aluminum foil, but not limited to this. For example, various kinds of barrier layers that are used as materials other than lithium ion secondary batteries can also be used.

The thickness of the barrier layer is not particularly limited. Generally, it is preferably 20 to 200 μm, and particularly preferably 30 to 150 μm.

In addition, it is preferable to perform surface treatment suitable for the exterior material of the lithium ion secondary battery on one or both sides of the barrier layer. Examples of the surface treatment include chemical conversion treatment and chromate treatment. In particular, these surface treatments are applied to the surface on the side where the barrier layer is in contact with the thermal welding layer.

The heat welding layer is not particularly limited as long as it can be heat-sealed, and for example, a known material suitable for a lithium ion secondary battery exterior material or the like can be used. Specifically, polyvinyl chloride, polyolefin film, etc. are suitably used. Examples of the polyolefin film include polyethylene, polypropylene, copolymers whose main component is polypropylene, and acid-modified products thereof. Either stretched film or unstretched film can be used as the heat welding layer.

The method for forming the thermal welding layer is not particularly limited, and for example, any method such as a method of applying a coating liquid containing a thermal welding component, a method of laminating a thin film of a resin composition containing a thermal welding component in advance, and the like can be used. .

The thickness of the heat welding layer is not particularly limited as long as the desired heat sealability can be obtained. Generally speaking, it is preferably about 20 to 200 μm, and more preferably 30 to 100 μm. B. Characteristics of the film of the present invention

The thickness (total thickness) of the film of the present invention can be appropriately set according to the application, usage method, and the like. For example, when the film of the present invention is used as a battery exterior material, it is preferably about 10 to 25 μm, particularly preferably 15 to 25 μm.

In addition, the film system of the present invention is expected to have high thickness accuracy (thickness uniformity). That is, the standard deviation value relative to the average thickness is usually preferably 0.200 or less, particularly preferably 0.180 or less, and most preferably 0.160 or less.

The evaluation method of the above-mentioned thickness accuracy is performed in the following manner. After humidifying the film of the present invention at 23° C.×50% RH for 2 hours, as shown in FIG. 3, after determining the reference direction (0 degree direction) at any point A on the designated film, from the center point A toward the reference Direction (a), clockwise 45 degrees direction (b), 90 degrees direction (c), 135 degrees direction (d), 180 degrees direction (e), 225 degrees direction (f), 270 degrees A total of 8 straight lines L1 to L8 of 100 mm are drawn in 8 directions such as the direction (g) and the 315-degree direction (h). Using a length gauge "HEIDENHAIN-METRO MT1287" (manufactured by Heidenhain) on each straight line, the thickness is measured at 10 mm intervals from the center point A (measurement of 10 points). As an example, FIG. 3 is used to show the state of determining the measurement point (10 points) when measuring L2 in the direction of 45 degrees. Then, the average value of the measured values of 80 points of data measured on all straight lines is calculated, and the average thickness is used as the average thickness to calculate the standard deviation value relative to the average thickness. In addition, the above-mentioned reference direction is not particularly limited, and for example, MD in the stretching step at the time of film manufacturing may be used as the reference direction.

In the present invention, the average thickness and the standard deviation may be based on the point (point A) at any position of the polyamide film, especially for the polyamide film obtained by being wound on the film roll. In other words, it is more desirable that any of the following three points be the average thickness and standard deviation within the above range. The 3 points are at the following positions: a) near the center of the web and equivalent to half of the volume; b) near the right end of the web and equivalent to half of the volume; and c) near the left end of the web And it is the position near the end of the winding.

The film of the present invention has excellent electrolyte resistance, and the film which is an index satisfying the value of the following general formula (1) is preferred. (HzX)－(Hz0)＜3.0　　　…Formula (1)

Hz0: Haze value measured according to Japanese Industrial Standard "JIS K 7136". In addition, the measurement of the haze value can be performed using a commercially available measuring device (for example, a haze meter "NDH 4000" manufactured by Nippon Denshoku Corporation).

HzX: After measuring Hz0, with the electrolyte shown below attached to the protective layer, after 12 hours at a temperature of 23°C and a humidity of 50% RH, the haze value measured in the same manner as Hz0 was used.

For the electrolyte, a liquid prepared by mixing LiPF _{6 in} a mixed liquid composed of ethylene carbonate/diethyl carbonate/ethyl methyl carbonate=1:1:1 (volume ratio) and diluting it to 1 mole/ L concentration. 10 ml of this electrolyte was dropped on the protective layer side, and it was left at a temperature of 23° C. and a humidity of 50% RH for 12 hours with the electrolyte attached. After that, wipe the electrolyte on the protective layer with gauze and measure Hz0.

In this way, the haze value before dropping the electrolyte is Hz0, and the haze value measured after leaving the electrolyte for 12 hours is HzX.

As mentioned above, the value of the above general formula (1) is generally less than 3, particularly preferably 2 or less, and more preferably 1.8 or less, and most preferably 1 or less. If the value of the above general formula (1) is large, it means that corrosion caused by the electrolyte resistance has occurred, and as a result, albinism occurs, indicating poor electrolyte resistance. The lower limit of this value is not particularly limited, and may be 0.1, for example.

In addition, the haze value (Hz0) of the film of the present invention before the electrolyte is dropped is not particularly limited, but in the case of use in applications requiring transparency in particular, it is usually preferably 10 or less, and preferably 5 or less. In addition, the lower limit value of the haze value (Hz0) is not particularly limited, and may be about 0.1, for example.

Furthermore, as an indicator of excellent electrolyte resistance, the film of the present invention preferably satisfies the following general formula (2). (HzY)－(Hz0)＜3.0　　　…Formula (2)

Hz0: Haze value measured according to Japanese Industrial Standard "JIS K 7136". In addition, the measurement of the haze value can be performed using a commercially available measuring device (for example, a haze meter "NDH 4000" manufactured by Nippon Denshoku Corporation).

HzY: After measuring Hz0, with the electrolyte shown below attached to the protective layer, after 24 hours at a temperature of 23°C and a humidity of 50% RH, the haze value measured in the same manner as Hz0 was used.

For the electrolyte, a liquid prepared by mixing LiPF _{6 in} a mixed liquid composed of ethylene carbonate/diethyl carbonate/ethyl methyl carbonate=1:1:1 (volume ratio) and diluting it to 1 mole/ L concentration. 10 ml of this electrolyte was dropped on the protective layer side to attach the electrolyte, and left at a temperature of 23° C. and a humidity of 50% RH for 24 hours. After that, wipe the electrolyte on the protective layer with gauze and measure Hz0.

In this way, the haze value before dropping the electrolyte is Hz0, and the haze value measured after leaving the electrolyte for 24 hours is HzY.

As described above, the value of the general formula (2) is generally less than 3, particularly preferably 2.6 or less, more preferably 2 or less, and even more preferably 1.8 or less, and most preferably 1 or less. The lower limit of this value is not particularly limited, and may be 0.1, for example.

In this way, the film system of the present invention satisfying the above general formula (1) or satisfying the above general formulas (1) to (2) can more reliably exhibit excellent electrolyte resistance. That is, there was little change in haze after being left for 12 hours after the electrolyte was attached, and there was almost no change in haze after being left for 24 hours. This means that even if it is left for a long time in the state where the electrolyte is attached, not only can the change in haze before and after attachment be suppressed, but also the change in appearance or the decrease in strength can be effectively suppressed. 2. Manufacture of polyamide-based laminated film

The film of the present invention can be suitably manufactured by a method of manufacturing a polyamide-based laminated film including the following steps: (1) A step of applying a coating liquid for forming a protective layer containing a copolymerized polyester resin to an unstretched polyamide-based film or a uniaxially stretched polyamide-based film, the copolymerized polyester resin containing a dicarboxylic acid component and The diol component is a constituent component, and the dicarboxylic acid component having a naphthalene skeleton in 100 mol% of structural units derived from dicarboxylic acid is 50 mol% or more (coating step); and (2) Extend the polyamide-based film having the coating film obtained by the aforementioned coating, thereby obtaining protection on one or both sides of the biaxially stretched film that has been extended in the MD and TD directions The layer of polyamide is a step of laminating a film (stretching step).

In the production of the film of the present invention, the method for forming the protective layer is not limited, and any method such as in-line coating method and post-coating method can be used.

In particular, the present invention preferably uses an in-line coating method. That is, it is preferable to adopt the following method: stretch the unstretched film or uniaxially stretched film on which the coating film obtained by the coating liquid for forming a protective layer has been formed together with the aforementioned coating film. Therefore, a manufacturing method including the above coating method and extension method is suitable. In the present invention, by adopting the in-line coating method, the protective layer can be smoother than the later coating method, and a thinner protective layer with a uniform thickness can be formed. In addition, as described above, the electrolyte resistance of the protective layer containing the copolymerized polyester resin is also improved.

In the manufacturing method of the present invention, as long as it has the coating step and the extending step as described above, the order is not particularly limited. For example, 1) a method of performing biaxial stretching simultaneously or sequentially after applying a coating liquid for forming a protective layer on an unstretched polyamide-based film; 2) a method of sequentially performing biaxial stretching After applying the coating liquid for forming a protective layer on the axially stretched polyamide-based film, any method such as a method of extending in a direction (MD direction or TD direction) orthogonal to the aforementioned uniaxial direction. The steps are explained in detail below. Coating steps

In the coating step, a coating liquid for forming a protective layer containing the copolymerized polyester resin (copolymerized polyester resin A) (coating liquid of the present invention) is applied to an unstretched polyamide-based film or uniaxially stretched polyamide An amine-based film, the copolymerized polyester resin A contains a dicarboxylic acid component and a diol component as constituent components, and the dicarboxylic acid component having a naphthalene skeleton in 100 mol% of structural units derived from the dicarboxylic acid is 50 mol %the above.

In this case, the aforementioned unstretched polyamide-based film or uniaxially stretched polyamide-based film can be used as the substrate of the polyamide-based film of the film of the present invention, in addition to the use of known films, Films produced according to known methods can also be used.

For example, an unstretched polyamide-based film can be obtained by forming a melt-kneaded product containing a polyamide-based resin into a film shape. The preparation of the melt-kneaded substance itself may be performed according to a known method. For example, it can be produced by molding a melt-kneaded product obtained by melting a resin composition containing a polyamide resin into a film shape. This can be done by using known or commercially available equipment. For example, a melt extruder with a T-shaped die can be used. That is, first, the starting material (for example, round raw materials) is supplied to the hopper, plasticized and melted in the melt extruder, and the melt-kneaded material is extruded into a sheet form from the T-shaped die installed at the front end of the extruder, and The cast roll is cooled and solidified. At this time, the unstretched film can be obtained by pressing the molten kneaded material against the casting roll with air.

In the above-mentioned resin composition, in addition to the polyamide resin, various additives can be formulated as needed. Examples of additives include additives added to polyamide-based film substrates.

In addition, for the uniaxially stretched polyamide-based film, for example, a film obtained by uniaxially stretching the aforementioned unstretched polyamide-based film can be used.

The coating liquid of the present invention contains a copolymerized polyester resin containing a dicarboxylic acid component and a diol component as constituent components, and having a dicarboxylic acid having a naphthalene skeleton in 100 mol% of structural units derived from the dicarboxylic acid The acid content is more than 50 mol%. As such a copolymerized polyester resin, the aforementioned resins can be used.

The method for preparing the coating liquid of the present invention can be implemented by dissolving or dispersing the copolymerized polyester resin A in a solvent. That is, the coating liquid of the present invention can be formulated in the form of a solution or dispersion.

The solvent is not particularly limited, and in addition to water, alcohols such as methanol, ethanol, and isopropanol; thiocello such as butylcellulose; toluene, methyl ethyl ketone (MEK), cyclohexanone, Solvesso Organic solvents such as ^TM , isophorone, xylene, methyl isobutyl ketone (MIBK), ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, etc. One or more of these can be used. In the present invention, it is preferred to use a) water or b) a mixed solvent of water and a water-soluble organic solvent. That is, from the viewpoint of workability, environmental aspects, etc., the coating liquid for forming a protective layer is preferably an aqueous coating agent whose main component is water and is water-soluble or aqueous dispersion, and from the viewpoint of coating properties The water dispersion is preferred. In this case, the cross-linking agent is preferably water-based. In addition, for the purpose of shortening the drying step and improving the stability of the coating liquid, an organic solvent such as alcohol may be contained in a small amount.

The concentration of the copolymerized polyester resin A in the coating liquid of the present invention can be appropriately set according to the type of the copolymerized polyester resin used, etc., and is usually 3 to 40% by mass, and particularly preferably 5 to 20% by mass.

In addition to the copolymerized polyester resin A, the coating liquid of the present invention may contain other components within a range that does not impair the effects of the present invention. For example, various additives exemplified above can be blended.

The coating liquid for forming a protective layer containing a copolymerized polyester resin used in the present invention preferably has a solid concentration adjusted appropriately according to the specifications of the coating device or the drying/heat treatment device. However, a coating solution that is too thin is difficult to form a protective layer having a thickness sufficient to exhibit resistance to an acidic liquid such as an electrolytic solution. In addition, a problem that requires a long time is likely to occur in the subsequent drying step. On the other hand, a coating solution having a too high concentration is unlikely to become uniform, and problems in coating properties are likely to occur. From such a viewpoint, the solid content concentration of the coating liquid for forming a protective layer is preferably about 5 to 70% by mass, but it is not limited thereto.

The coating liquid for forming a protective layer containing a copolymerized polyester resin used in the present invention may be prepared by a known method using a furnace or the like equipped with a stirrer.

The method of coating using the coating liquid of the present invention is not particularly limited, and a known method can be suitably used. For example, gravure roll coating method, reverse roll coating method, ring bar coating method, air knife coating method, curtain coating method, blade coating method, die coating method, dip coating method, bar coating method, etc. In addition, you can also use a combination of these methods.

After the coating liquid of the present invention is applied, the solvent may be removed by drying as needed, but the liquid film or the semi-dry film before drying may be supplied to the extension step.

The drying step after coating is not particularly limited, and drying may be performed using a known method such as drying treatment in a drying gas environment such as an oven, drying treatment in contact with a heat roller, and drying treatment in an extension machine. The drying temperature is not particularly limited, and can generally be set in the range of about 30 to 160°C. The drying time can be appropriately set according to the drying temperature, and generally set within a range of 0.5 to 10 minutes. Extended steps

The polyamide-based film having the coating film obtained by the foregoing coating through the above-mentioned coating step is stretched to form on one side or both sides of the biaxially stretched film that has been extended in the MD and TD directions Polyamide-based laminated film with protective layer.

Before performing the stretching step, it is preferable to preheat the unstretched film or the uniaxially stretched film. The preheating temperature is not limited, and it is usually 180 to 250°C, particularly preferably 200 to 245°C, and 210 to 240°C is the best. By preheating, a biaxially stretched film with good physical properties can be more reliably obtained. Although the preheating time depends on the preheating temperature and the like, it is usually about 0.5 to 5 seconds.

The method of preheating is not particularly limited. For example, a method implemented by setting the temperature of the hot air blown to the film passing through the preheating zone of the stretching machine within the above temperature range is suitable.

In addition, the method of setting the stretching temperature to the above temperature is not limited, and it is preferably performed by setting the temperature of the hot air blown to the film passing through the stretching zone of the stretching machine within the above temperature range. In this case, the time for the polyamide-based film to pass through the extension zone is usually about 0.5 to 5 seconds.

As the stretching method, since the film of the invention biaxially stretched is finally obtained, the simultaneous biaxial stretching method or the sequential biaxial stretching method can be used. In addition, the classification by the stretching device includes, for example, a tube method, a tenter method, etc., any of which can be used. In the present invention, particularly in terms of quality stability and dimensional stability, the stretching method by the tenter method is preferable. Therefore, it is suitable to use the tenter simultaneous biaxial stretching method or the tenter sequential biaxial stretching method.

In addition, when the sequential biaxial stretching method is used as the stretching method, a coating liquid for forming a protective layer may be applied to a film that has been uniaxially stretched in the MD direction or TD direction, and then orthogonal to its uniaxial direction Direction (TD direction or MD direction), thereby obtaining a predetermined film of the present invention in which a protective layer is formed on the biaxially stretched film.

The stretching magnification is not particularly limited, and generally it only needs to be extended by about 2.0 to 4.5 times in the MD direction and the TD direction. In this case, the extension magnification in the MD direction and the TD direction may be the same as each other or different. In this way, a stretched film having good physical properties such as tensile strength and tensile elongation can be obtained.

The stretching temperature is not limited, and for example, it can be appropriately set within a range of 220° C. or less in accordance with the stretching method, the use of the film of the present invention, and the use form.

For example, in the sequential biaxial stretching method, first, the unstretched film is stretched in the uniaxial direction at a stretching temperature of 40 to 80°C (preferably 50 to 65°C), and then a coating liquid for forming a protective layer is applied. The uniaxially stretched film coated with the coating liquid for forming the protective layer may be dried at 50 to 220°C in the same manner as the above simultaneous biaxially stretched method. After that, the uniaxially stretched film coated with the coating liquid for forming the protective layer is stretched in an orthogonal direction under the condition that the stretching temperature is 200°C or lower (preferably 90 to 190°C) to obtain a biaxially stretched film . When performing successive biaxial stretching, it is preferable to use a roll stretching method and a tenter method together. That is, after stretching in a uniaxial direction (TD direction or MD direction) using a roller (usually a device that stretches the film while passing through two or more rollers), the tenter is used at a slight right angle to the uniaxial direction The direction (TD direction or MD direction) extends to enable biaxial extension.

For another example, in the simultaneous biaxial stretching method, after drying at 50 to 220°C in the drying step, a protective layer is coated under the condition of an extension temperature of 215°C or lower (preferably 190 to 210°C) The unstretched film of the coating liquid for forming is simultaneously biaxially stretched. When the unstretched film is simultaneously biaxially stretched, the tenter method, LISIM biaxial stretching method, or the like is preferably used.

The film stretched in the stretching step is preferably further heat-treated. The heat treatment temperature is not particularly limited, but it is usually preferably 190 to 220°C, particularly preferably 195 to 215°C. If the heat treatment temperature does not reach 190°C, the coating film of the copolymer polyester resin may be insufficiently formed, and a protective layer having insufficient resistance to the electrolyte may be formed. In addition, when the hardener is added, the crosslinking reaction may not proceed sufficiently, and the effect of adding the crosslinker may not be obtained. On the other hand, if the heat treatment temperature exceeds 220°C, the strength of the polyamide film will decrease. In addition, when the cross-linking reaction does not sufficiently proceed in the above heat treatment, the aging treatment may be performed after the stretching is completed. The time of the heat treatment can be appropriately set according to the heat treatment temperature, etc., usually about 1 to 15 seconds.

The heat treatment method is not particularly limited, and for example, a method of blowing hot air, a method of irradiating infrared rays, a method of irradiating microwaves, or the like can be used. From the viewpoint of being able to heat uniformly and accurately, the method of blowing hot air is preferred among these. For example, a method of heat fixing can be performed by blowing hot air that has been set in the above temperature range to the film passing through the heat fixing area of the stretching machine. Other steps

The method of laminating each layer is not particularly limited, and for example, a) a method of forming a coating film obtained by a coating solution, b) a method of laminating a preformed thin film, c) forming a vapor-deposited film by a PVD method, a CVD method, etc. Any of the methods. In addition, in the case of the above b), any one of a method of laminating through an adhesive, a method of laminating by simultaneous extrusion molding, and the like may also be used. In particular, when the thin film of the present invention is used as a battery exterior material such as a lithium ion secondary battery, a known method for manufacturing an exterior material can also be used. In this case, a known adhesive can also be used for lamination.

For example, in the case of lamination with a barrier layer, a laminate including a protective layer/polyamide-based film substrate or a laminate including a protective layer/polyamide-based film substrate/protective layer, and a barrier layer A method of forming a metal foil or the like to perform dry lamination, heat lamination, etc. through a two-component polyurethane adhesive or the like.

In addition, a known method (dry lamination, heat lamination, extrusion lamination, sandwich lamination method, etc.) can be used as a method of joining the barrier layer and the thermal fusion bonding layer.

As long as the surface of the polyamide film, barrier layer, and heat welding layer that can form the adhesive layer described above, as long as the effect of the present invention is not impaired, other layers such as an anchor coating layer and a primer layer may be provided as necessary. 3. Use of Polyamide-based laminated film

The film of the present invention can be used in various applications, and is particularly suitable as a packaging material. That is, it can be used as a packaging material for packaging contents. The content is not limited, and it can package contents such as electronic parts, chemical products, cosmetics, medical supplies (medical equipment), beverages and food.

In particular, the film of the present invention is suitable for use as an exterior material for lithium ion secondary batteries. When the film of the present invention is used as an exterior material, the film of the present invention (especially the polyamide-based group) can be protected by its protective layer Material layer) is not affected by the electrolyte. As a result, it is possible to effectively suppress or prevent problems caused by corrosion of exterior materials and the like.

In general, an electrolyte used for a lithium ion secondary battery is a conductive liquid prepared by dissolving an ionic substance (especially a lithium salt) in a polar solvent such as carbonate. The lithium salt may be a lithium salt that generates hydrofluoric acid (hydrogen fluoride) by reaction with water. More specifically, fluorine-containing lithium salts such as lithium hexafluorophosphate (LiPF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ) are listed. Therefore, when the electrolyte is attached to the air, moisture in the air reacts with the fluorine-containing lithium salt in the electrolyte to generate hydrofluoric acid. Due to this hydrofluoric acid, there is a possibility that the polyimide film used for the exterior material of the lithium ion secondary battery dissolves. In this regard, since the film of the present invention is coated with the above-mentioned specific protective layer, the polyamide-based film substrate can be effectively used with high electrolyte resistance even if the electrolyte contacts the exterior material (especially the protective layer) As a result, the exterior materials are protected, and as a result, a highly reliable lithium ion secondary battery can be provided. Therefore, the film of the present invention is suitable for use as, for example, a lithium ion secondary battery exterior material, and can also be applied to embossed or deep drawing molded lithium ion secondary batteries. Then, when manufacturing a lithium ion secondary battery, even if the electrolyte adheres to the exterior side, the performance as an exterior material of the lithium ion secondary battery can be maintained well.

When it is used as a packaging material, its form is not particularly limited. For example, it can be used as a packaging bag or a packaging container. As a packaging bag, it can be used as various bag bodies, such as a pillow bag, a gusset bag, a support bag, etc., for example. The method of forming the bag body may be performed according to a known method.

In addition, the present invention also includes products (packaged products) whose contents are packed by the aforementioned packaging materials or packaging bags. The packaging state in this case includes, for example, a state in which the contents are sealed from the outside by a packaging material or a packaging bag. 4. Battery

The present invention includes a battery including: a power generation element including a negative electrode, a positive electrode, a separator, and an electrolyte; and an exterior material to package the power generation element; characterized in that the aforementioned exterior material is the film of the present invention and is configured as The protective layer serves as the outermost layer of the battery.

According to the packaging form of the battery, it can be divided into a can type and a laminated type (pouch type). The film of the present invention is suitable for a laminated type (pouch type) battery. Therefore, in addition to, for example, a method in which the film of the present invention is preliminarily formed into a concave shape (container shape) and then filled with a power generating element and sealed, it is also possible to use the film of the present invention after placing the power generating element in the film of the present invention. The method of forming the envelope to seal the power generation elements, etc.

The power generation element is not particularly limited, and a known or commercially available power generation element can also be used. In addition, it may be either a primary battery or a secondary battery. For example, a lithium ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, etc. are mentioned.

A schematic diagram of the battery is shown in FIG. 4. The battery 40 has a structure in which the power generating element 41 is covered with an exterior material composed of the film 10 of the present invention. More specifically, the power generating element 21 is covered with the film 10 of the present invention such that the surface of the protective layer 10a of the film 10 of the present invention is located outside.

The power generation element 41 in FIG. 4 includes a positive electrode composed of a positive electrode active material and a current collector, a separator, a negative electrode composed of a negative electrode active material and a current collector, an electrolyte, etc. (none of which are shown). In addition, the positive electrode and the negative electrode each have a lead (tab) 43 extending from the end.

Taking a lithium ion battery as an example, the following configuration can be adopted. Examples of the positive electrode active material include lithium metal in addition to lithium salts such as lithium manganate, and examples of the positive electrode current collector include aluminum foil. Examples of the separator include microporous membranes such as polyethylene and polypropylene. Examples of the negative electrode active material include graphite, and lithium salts such as lithium manganate and metal lithium can be used. Examples of the positive electrode current collector include aluminum foil. The electrolytic solution may be a solution in which lithium salts such as lithium tetrafluoroborate (LiBF ₄ ) and lithium hexafluorophosphate (LiPF ₆ ) are dissolved in ethyl carbonate (EC), ethyl methyl carbonate (EMC), propylene carbonate, or the like.

FIG. 5 is a cross-sectional view showing an example of a battery using the film body of the present invention as an exterior material. In the battery 50, the film 10 of the present invention used as an exterior material is folded in half so that the protective surface 10a is located outside, and the power generation element 41 is filled therein. The surface located on the opposite side of the protective layer of the thin film 10 of the present invention is the thermal fusion bonding layer 10b, and the adhesive portion S1 is formed by heat sealing in a state where its ends are opposed to each other. At this bonding portion S1, the lead wire 43 is sandwiched between the heat welding layers. In FIG. 4, for simplicity, only one lead 43 is shown, but actually, a positive electrode lead and a negative electrode lead are provided.

When assembling the battery shown in FIG. 5, in the power generating element 41 provided with the lead 43, the film 10 of the present invention is used to cover the power generating element 41 so that the lead is exposed to the outside. At the time of coating, the power generating element 21 is coated by bonding the thermal fusion bonding layers 10b of the film 10 of the present invention to each other. In this case, a part is not joined to ensure an injection port for the electrolyte. Next, after filling the electrolyte from the injection port, the injection port is closed by heat sealing. In this manner, the power generation element 21 is sealed using the film 10 of the present invention as an exterior material.

In addition, FIG. 6 shows a schematic diagram of a cross section of a battery of another embodiment. The battery 60 has a power generating element (power generating element) 41 for connecting to an external lead 43, and its periphery is covered with two thin films 10 and 10 of the present invention. Both ends of the films 10 and 10 of the present invention are sealed by the adhesive portions S1 and S2 obtained by heat sealing or the like. The lead wire 43 extends so as to be exposed from the electrode in the battery 60 to the outside, and can take out the current from the power generating element 41 to the outside. In FIG. 6, for simplicity, only one lead 43 is shown, but actually, a positive electrode lead and a negative electrode lead are provided.

When assembling the battery 60 shown in FIG. 6, for the power generating element 41 provided with the lead 43, the power generating element 41 of the present invention is covered with the thin films 10 and 10 of the present invention so that the lead is exposed to the outside. At the time of coating, the power generating element 21 is coated by heat-sealing the two layers 10b, 10b of the two films 10, 10 of the present invention to each other through heat sealing. In this case, a part is not joined to ensure an injection port for the electrolyte. Next, after filling the electrolyte from the injection port, the injection port is closed by heat sealing. In this way, the sealing of the power generating element 41 is performed by using two films 10 and 10 of the present invention. [Example]

Examples and comparative examples are shown below, and the features of the present invention are explained more specifically. However, the scope of the present invention is not limited by the examples. In addition, "parts" described below means "parts by mass". Example 1 (1) Synthesis of copolymerized polyester resin A

Dicarboxylic acid component (709.4 parts of 2,6-naphthalene dicarboxylic acid, 26.6 parts of terephthalic acid, 56.2 parts of 5-sulfoisophthalic acid sodium), glycol component (176.7 parts of ethylene glycol, diethylene glycol 126.2 parts, 336.8 parts of 1,6-hexanediol), and 0.26 parts of tetrabutyl titanate as a polymerization catalyst were added to the reactor, and the system was replaced with nitrogen. Then, while stirring these raw materials at 1000 rpm, the reactor was heated to 200°C.

Next, it took 4 hours to gradually raise the temperature to 260°C and subject it to transesterification. Thereafter, the pressure was gradually reduced at 250°C, and the polycondensation reaction was carried out at 0.35 mmHg for 1.5 hours. In this way, a predetermined copolymerized polyester resin is prepared. (2) Preparation of coating liquid for protective layer formation

The obtained copolymerized polyester resin was pulverized, 30 parts of copolymerized polyester resin and 70 parts of water were added to a dissolution tank, and stirred at 80 to 95°C while dissolving for 2 hours, thereby obtaining an aqueous solution having a concentration of 30% by mass as Coating liquid for forming a protective layer. (3) Manufacture of stretched film (simultaneous biaxial stretching)

Using an extruder equipped with a T-die, a polyamide resin (nylon 6, "A1030BRF" manufactured by Unitika Corporation, relative viscosity 3.1) was extruded into a sheet form from the T-die at 260°C. Next, it was made to adhere to a casting roll whose surface temperature was adjusted to 18° C. for rapid cooling, and the supply amount of the polyamide resin was adjusted so that the thickness of the polyamide film obtained after stretching was 15 μm.

Next, this unstretched film was passed through a water absorption treatment device with a water temperature of 50° C., and the coating liquid for forming a protective layer was applied to one side of the unstretched film using a fountain method so that the thickness after drying would be 0.70 μm. After the cloth was dried at 150°C, it was introduced into a simultaneous biaxial stretching machine. In the simultaneous biaxial stretching machine, the coated unstretched film was simultaneously biaxially stretched in the MD direction 3.0 times and the TD direction 3.3 times under the conditions of a preheating temperature of 200°C and a stretching temperature of 190°C. Next, heat treatment was performed under the conditions of a heat treatment temperature of 210° C. and a heat treatment time of 3 seconds to form a protective layer on one side of the polyamide film. Furthermore, the other surface without the protective layer was subjected to corona treatment, and a stretched film with a film thickness of 15 μm and a protective layer thickness of 0.70 μm was obtained. (4) Fabrication of polyamide-based laminated film

On the surface of the protective layer of the unstretched stretched film, a two-component polyurethane adhesive (manufactured by Toyo Morton, TM-K55/CAT-10L) was applied at a coating amount of 5 g/m ² at 80°C. Dry for 10 seconds. An aluminum foil (thickness 50 μm) was laminated on the adhesive application surface. Next, the aluminum foil surface was coated and dried under the same conditions using the above-mentioned adhesive, and an unstretched polypropylene film (manufactured by Mitsui Chemicals Tohcello Co., GHC, thickness 50 μm) was bonded as a heat-welded layer, and was bonded at 40° C. 72 hours of aging treatment under the gas environment. In this way, a polyamide-based laminated film laminated in the order of "protective layer/polyamide film/aluminum foil/thermal welding layer" was obtained. Examples 2 to 19 and Comparative Examples 1 to 6

>關於實施例2> (2)保護層形成用塗覆液的調製Except for the conditions shown in Table 1 and below, a polyamide-based laminated film was produced in the same manner as in Example 1. In addition, *1 in Table 1 shows the example of the coating method after use. [Table 1]

>About Example 2> (2) Preparation of coating liquid for forming protective layer

唑啉系交聯劑(日本觸媒公司製「WS300」)，以交聯劑含量相對於共聚聚酯樹脂之固形分為5質量%的方式添加，並進一步與純水混合，使共聚聚酯樹脂與交聯劑之混合物的固形分為9質量%而獲得保護層形成用塗覆液。 (3)延伸薄膜的製造(同時雙軸延伸)Use the copolymerized polyester resin described in Example 1 and the one described in Table 1.

An oxazoline-based crosslinking agent ("WS300" manufactured by Japan Catalyst Co., Ltd.) is added in such a way that the content of the crosslinking agent is 5 mass% relative to the solid content of the copolymerized polyester resin, and further mixed with pure water to make the copolymerized polyester The solid content of the mixture of resin and crosslinking agent was 9% by mass to obtain a coating liquid for forming a protective layer. (3) Manufacture of stretched film (simultaneous biaxial stretching)

A polyamide-based laminated film was obtained in the same manner as in Example 1, except that the heat treatment temperature when forming the protective layer on one side of the polyamide-based film was changed to the value shown in Table 1. >About Example 5> (1) Synthesis of copolymerized polyester resin A

A copolymerized polyester resin was obtained in the same manner as in Example 1, except that the blending ratio of the dicarboxylic acid component and the diol component was changed to the composition shown in Table 1. (2) Preparation of coating liquid for protective layer formation

Under the conditions shown in Table 1, a crosslinking agent was added to the above copolymerized polyester resin, and 9% by mass of a coating liquid for forming a protective layer was obtained using pure water. (3) Manufacture of stretched film (sequential biaxial stretching)

Using an extruder equipped with a T-shaped die, nylon 6 (manufactured by Unitika, A1030BRF, relative viscosity of 2.7) was extruded into a sheet form from the T-shaped die at 260°C. Next, it was made to adhere to a casting roll whose surface temperature was adjusted to 18° C. for rapid cooling, and the supply amount of the polyamide resin was adjusted so that the thickness of the polyamide film obtained after stretching became 15 μm.

Next, the unstretched film was stretched in the MD direction to a stretch ratio of 2.80 by passing through a stretching roller heated to 54°C to 62°C. Next, using the coating liquid for forming the protective layer, using a gravure coater on one side of the stretched film, after coating so that the thickness after drying becomes 0.70 μm, the preheating temperature is 60° C. and the stretching temperature is 90 Under the condition of ℃, the extension ratio is 3.2 times in the TD direction. Further, heat treatment was performed under the conditions of a heat treatment temperature of 215°C and a heat treatment time of 3 seconds. Further, the other surface of the polyamide film without the protective layer was subjected to corona treatment, and an extended film with a film thickness of 15 μm and a protective layer thickness of 0.70 μm was obtained. Using the obtained stretched film, a polyamide-based laminated film was obtained in the same manner as in Example 1. >About Example 6>

A polyamide-based laminated film was produced in the same manner as in Example 5 except that the heat treatment temperature was changed as shown in Table 1. >About Examples 3 to 4, 9, 16 to 18, Comparative Example 2>

A polyamide-based laminated film was obtained in the same manner as in Example 2 except that the composition of the coating liquid for forming a protective layer and the heat treatment temperature at the time of forming the protective layer were set to the conditions shown in Table 1. >About Examples 6 to 8, 10 to 15>

A polyamide-based laminated film was obtained in the same manner as in Example 5, except that the composition of the coating liquid for forming a protective layer and the heat treatment temperature at the time of forming the protective layer were set to the conditions shown in Table 1. >About Example 19> (3) Manufacture of stretched film (simultaneous biaxial stretching)

Using an extruder equipped with a T-shaped die, nylon 6 (manufactured by Unitika, A1030BRF, relative viscosity of 2.7) was extruded into a sheet form from the T-shaped die at 260°C. Next, it was made to adhere to a casting roll whose surface temperature was adjusted to 18° C. for rapid cooling, and the supply amount of the polyamide resin was adjusted so that the thickness of the polyamide film obtained after stretching became 15 μm. Next, this unstretched film was passed through a water absorption treatment device with a water temperature of 50° C., and was continuously introduced into a simultaneous biaxial stretching machine. Under the conditions of a preheating temperature of 200°C and an extension temperature of 190°C, biaxial stretching was performed while 3.0 times in the MD direction and 3.3 times in the TD direction. Next, heat treatment was performed under the conditions of a heat treatment temperature of 210° C. and a heat treatment time of 3 seconds, and one side was further subjected to corona treatment to obtain a polyamide film having a film thickness of 15 μm. Further, the obtained polyamide film was introduced into a gravure coater, and the coating solution for forming a protective layer obtained in Example 2 was applied so that the final coating thickness became 0.7 μm, and it took time 3 Secondly, it is dried in a 5-zone drying oven [Zone 1 (80°C) → Zone 2 (100°C) → Zone 3 (120°C) → Zone 4 (110°C) → Zone 5 (80°C)], thereby obtaining a film A stretched film with a thickness of 15 μm and a protective layer thickness of 0.70 μm. Then, in the same manner as in Example 1, a polyamide-based laminated film was produced. >About Comparative Example 1>

A polyamide-based laminated film was obtained in the same manner as in Example 19 except that the composition of the coating liquid for forming a protective layer was set as described in Table 1, and the thickness of the protective layer was 2.00 μm. >About Comparative Example 3>

A polyamide-based laminated film was obtained in the same manner as in Comparative Example 1, except that the coating liquid for forming a protective layer was changed to a commercially available PVDC coating liquid (“Saran Latex L549” from Asahi Kasei Corporation). >About Comparative Example 4>

A polyamide-based laminated film was obtained in the same manner as in Example 1, except that the coating liquid for forming the protective layer was changed to the same PVDC coating liquid as in Comparative Example 3 and the heat treatment temperature at the time of forming the protective layer was changed. . >About Comparative Example 5>

A polyamide-based laminated film was obtained in the same manner as in Comparative Example 1, except that the coating liquid for forming a protective layer was changed to a saturated polyester resin emulsion (Takamatsu Oil Co., Ltd. A-110F). >About Comparative Example 6>

A polyamide-based laminate was obtained in the same manner as in Example 1, except that the coating liquid for forming the protective layer was changed to the same saturated polyester resin emulsion as Comparative Example 5 and the heat treatment temperature at the time of forming the protective layer was changed. film. Test Example 1

The following characteristics were measured for the polyamide-based laminated films obtained in the examples and comparative examples. The results are shown in Table 2. The "unmeasured" in Table 2 means that the surface of the polyimide-based laminated film is deformed due to wrinkles or the like after the electrolyte is attached, and therefore cannot be measured. (1) Composition of copolymerized polyester resin

¹ H-NMR was measured using an "ECZ400R NMR apparatus" manufactured by JEOL Ltd., and obtained from the peak integrated intensity ratio (integrated intensity) of the proton of each copolymerization component in the obtained chart. (2) Glass transition temperature of copolymerized polyester resin

A differential scanning pyrolysis analyzer (Diamond DSC) manufactured by Perkin Elmer Co., Ltd. was used for measurement at a temperature increase rate of 20°C/min. (3) Thickness of protective layer

After embedding the obtained polyamide-based laminated film with epoxy resin, it was subjected to planar processing, and then RuO ₄ staining (1 day) was performed, and slices with a thickness of 90 nm (set value) were taken using an ultra-thin slicer. The cutting temperature was set to 23°C × humidity 50% RH (around the sample, knife, chamber), and the cutting speed was 0.6 mm/min. The obtained sample used "JEM-1230" TEM manufactured by JEOL Ltd., and the thickness of the protective layer was measured by transmission measurement at an acceleration voltage of 100 kV. (4) Non-uniformity of thickness of laminated film (thickness accuracy)

As shown in FIG. 3, after the obtained polyamide-based laminated film is humidified at a temperature of 23° C. and a humidity of 50% RH for 2 hours, the reference direction (0 degree direction) is determined at the arbitrary point A on the designated film as the center ), from the center point A toward the reference direction, clockwise 45 degrees direction, 90 degrees direction, 135 degrees direction, 180 degrees direction, 225 degrees direction, 270 degrees direction, and 315 degrees direction Draw a total of 8 straight lines of 100mm each. Using a length gauge "HEIDENHAIN-METRO MT1287" (manufactured by Heidenhain) on each straight line, measure the thickness at 10 mm intervals from the center point A (measure 10 points), and calculate a total of 80 points of data measured on all straight lines The average of the values, and using this as the average thickness, calculate the standard deviation value relative to the average thickness. In addition, the above-mentioned reference direction is not particularly limited, and for example, MD in the stretching step at the time of film manufacturing may be used as the reference direction. (5) Surface roughness

The surface roughness of the protective layer of the obtained polyamide-based laminated film and the base surface of the polyamide-based film is based on the Japanese Industrial Standard JIS B0601-2013, using a contact-type surface roughness measuring device manufactured by Kosaka Research Institute Co., Ltd. "Suefcorder SE500A" measures 10 points arbitrarily and sets the calculated average value as Ra. (6) Resistance to electrolyte

Using the obtained polyamide-based laminated film, the electrolyte resistance was evaluated for three kinds of storage time of 6 hours, 12 hours, and 24 hours as shown below.

First, a haze meter (NDH4000) manufactured by Nippon Denshoku Corporation was used to measure the haze value of the obtained polyamide-based laminated film in accordance with Japanese Industrial Standard "JIS K 7136". Let it be the haze (Hz0) before the electrolyte is dropped.

Next, three samples were prepared in which the opening of a glass Petri dish (diameter 200 mm) was covered with a polyamide-based laminated film so that the protective layer became the surface. Drop 10 ml of electrolyte on the protective layer of each sample (already mixed with LiPF ₆ in a mixed solution consisting of ethylene carbonate/diethyl carbonate/ethyl methyl carbonate=1/1/1 (volume ratio) And dilute it to a concentration of 1 mole/L), so that the electrolyte adheres to the protective layer.

For the three samples, the three kinds of samples were placed at a temperature of 23° C. and a humidity of 50% RH for 6 hours, 12 hours, and 24 hours after the electrolyte was attached. For the three kinds of samples, after leaving each set time, wipe the electrolyte on the protective layer with gauze, use the haze meter (NDH4000) manufactured by Nippon Denshoku Corporation in the same manner as above and according to the Japanese Industrial Standard "JIS K 7136" for measurement.

The haze value measured after the electrolyte is attached at a temperature of 23°C and a humidity of 50% RH for 6 hours is determined as HzW, the haze value measured after 12 hours is determined as HzX, and the haze value measured after 24 hours is left Set to HzY.

Then, calculate the difference between each case and the Hz0 before the electrolyte dripping, (HzW)-(Hz0), (HzX)-(Hz0), (HzY)-(Hz0).

In the above calculation results, the value in line with practicability is less than 3.0, especially less than 2.0, and more preferably less than 1.0. (7) Wetting

The wetting system is measured according to Japanese Industrial Standard JIS K6768. A measured value of 42 dyn or more can be evaluated as good. (8) Anti-caking

300g of the obtained polyamide-based laminated film (when the protective layer is single-sided, the protective layer and the base material layer are overlapped, and when the protective layer is double-sided, the protective layer and the protective layer are overlapped) and loaded /cm ^{2 under} load, let it stand for 24 hours in a constant temperature bath with a temperature of 40°C and a humidity of 50%RH. After that, the sample was cut into strips with a width of 15 mm and a length of 100 mm, and was peeled at a speed of 200 mm/min using a tensile tester Autograph AG-I (manufactured by Shimadzu Corporation), and the highest value was determined as the peel strength value. Regarding the peel strength value, 50g/15mm or less was evaluated as agglomeration resistance "○", more than 50g/15mm and less than 80g/15mm was evaluated as agglomeration resistance "△", and 80g/15mm or more was evaluated as agglomeration resistance "×". As far as practicability is concerned, it must be at least “△” anti-caking. [Table 2]

The polyamide-based laminated film obtained in Examples 1 to 19 has a protective layer containing a copolymerized polyester resin having a composition specified in the present invention, and has a thickness of 1.5 μm or less, so it shows that even if the electrolyte adheres to the protection On the layer, the appearance of the polyamide film has good electrolyte resistance that does not change for at least 12 hours or more, and the blocking resistance is also good. In particular, the following protective layer is excellent in electrolyte resistance: the dicarboxylic acid component of the copolymerized polyester resin contains 80 mol% or more of the dicarboxylic acid component having a naphthalene skeleton, the glass transition temperature is 80° C. or higher, and contains Protective layer of cross-linking agent.

On the other hand, the polyamide-based laminated film obtained in Comparative Examples 1, 3, and 5 has a thick protective layer, and although it exhibits electrolyte resistance, it may not be able to be dried in such a short time of 3 seconds. Dry thoroughly to obtain poor resistance to caking.

In addition, in Comparative Examples 2, 4, and 6, because the composition of the protective layer is not specified according to the present invention, when the thickness of the protective layer is as thin as 1.50 μm or less, sufficient electrolyte resistance cannot be obtained. When reaching the protective layer, the polyamide-based laminated film will be whitened, which greatly damages the appearance. In Comparative Example 5, even if the thickness of the protective layer is thick, the polyamide-based laminated film is still whitened, which greatly impairs the appearance.

10: laminate 10’: laminate 10a: protection level 10b: Thermal fusion layer 11: Polyamide-based film substrate 12: protective layer 13: barrier layer 14: heat welding layer 20: laminate 20’: Laminated body 21.41: Elements of power generation 40, 50, 60: battery 43: Lead L1-L8: straight line S1, S2: Continued

FIG. 1 is a view showing an embodiment of the polyimide-based laminated film of the present invention.

FIG. 2 is a view showing an embodiment of the polyimide-based laminated film of the present invention.

FIG. 3 is a conceptual diagram showing a method for measuring the thickness accuracy of the polyamide-based laminated film of the present invention.

4 is an external view of a battery using the polyamide-based laminated film of the present invention as an exterior material.

FIG. 5 is a schematic diagram showing a battery structure using the polyamide-based laminated film of the present invention as an exterior material.

6 is a schematic diagram showing a battery structure using the polyamide-based laminated film of the present invention as an exterior material.

Claims (9)

A polyamide-based laminated film comprising a polyamide-based film substrate and a protective layer formed on at least one side of the substrate, characterized in that: (1) The protective layer is formed by directly contacting the surface of the polyamide-based film substrate; (2) At least one protective layer is configured as the outermost layer of the polyamide-based laminated film; (3) The protective layer contains a copolymerized polyester resin containing a dicarboxylic acid component and a diol component as constituent components, and having a naphthalene skeleton in 100% of the structural units derived from the dicarboxylic acid The carboxylic acid content is more than 50 mole %; and (4) The thickness of the protective layer is 1.5 μm or less. The polyimide-based laminated film according to claim 1, which satisfies the following general formula (1): (HzX)-(Hz0) <3.0 ... Formula (1) (However, the aforementioned Hz0 is based on the Japanese Industrial Standard "JIS K 7136 "The measured haze value, and the aforementioned HzX is the haze measured in the same manner as Hz0 after the measurement of the aforementioned Hz0, with the electrolyte attached to the protective layer, and after maintaining at a temperature of 23°C and a humidity of 50% RH for 12 hours. Degree, the aforementioned electrolyte is a solution in which LiPF _{6 is} diluted to a concentration of 1 mole/L in a mixed liquid composed of ethylene carbonate/diethyl carbonate/ethyl methyl carbonate=1:1:1 (volume ratio) ), and Hz0 is within the range of 10 or less. The polyamide-based laminated film according to claim 1, wherein the surface roughness (Ra) of the protective layer is 45 nm or less. The polyamide-based laminated film according to claim 1, wherein the glass transition temperature of the aforementioned copolymerized polyester resin is 60 to 145°C. The polyamide-based laminated film according to claim 1, wherein the protective layer further includes a melamine resin, an isocyanate compound, a carbodiimide compound and

At least one of the oxazoline compounds. The polyamide-based laminated film according to any one of claims 1 to 5, which is laminated in such a manner that the protective layer directly contacts at least one side of the polyamide-based film substrate, and is (a) A laminate including a protective layer, a polyamide-based film base material, a barrier layer, and a heat fusion layer in sequence, or (b) A laminate including a protective layer, a polyamide-based film base material, a protective layer, a barrier layer, and a heat welding layer in this order. The polyamide-based laminated film according to any one of claims 1 to 6, which is used for packaging articles. A battery characterized by comprising: Elements of power generation, including negative electrode, positive electrode, separator, and electrolyte; and Exterior materials, used to package the power generation elements, The aforementioned exterior material is a polyamide-based laminated film according to any one of claims 1 to 5, and the protective layer is configured as the outermost layer of the battery. A method for manufacturing a polyamide-based laminated film, which is a method for manufacturing a polyamide-based laminated film according to any one of claims 1 to 5, comprising: (1) A step of applying a coating liquid for forming a protective layer containing a copolymerized polyester resin to an unstretched polyamide-based film or a uniaxially stretched polyamide-based film, the copolymerized polyester resin containing a dicarboxylic acid component and The diol component is a constituent component, and the dicarboxylic acid component having a naphthalene skeleton in 100 mol% of the dicarboxylic acid component is 50 mol% or more; and (2) The polyamide-based film having the coating film obtained by the aforementioned coating is stretched to obtain a protective layer formed on one or both sides of the biaxially stretched film that has been extended in the MD and TD directions The polyamide is a step of laminating the film.

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