TWI790998B - Polyamide-based film, laminate body and container with using the film, and method for producing same - Google Patents

Abstract

Provided are a polyamide-based film having superior thickness uniformity and high resistance against electrolyte as well as comparatively little variation in properties in four directions formed of the 0 degree direction, 45 degree direction, 90 degree direction and 135 degree direction, and a method for producing the same. The present invention relates to a polyamide-based film comprising polyamide –containing base layer and a protective layer, (1) wherein the protective layer contains (A) vinyl alcohol based polymer containing a vinyl alcohol unit and (B) vinyl polymer containing an unsaturated carboxylic acid unit, (2) wherein a) the difference between the maximum value and minimum value of the respective stress at 5% elongation as determined by a uniaxial tensile test is 35 MPa or less in four directions formed of a specific direction from an arbitrary point in the film that is designated as 0 degrees and directions at 45 degrees, 90 degrees and 135 degrees relative to the specific direction in the clockwise direction, b) the difference between the maximum value and the minimum value of the respective stress at 15% elongation as determined by the uniaxial tensile test in the four directions is 40 MPa or less.

Description

Polyamide-based film, laminate and container using same, and manufacturing method thereof

Field of the Invention The present invention relates to a novel polyamide-based film and a method for producing the same. Furthermore, the present invention relates to a laminate and a container including the aforementioned polyamide-based film.

Background of the Invention Various resin films are processed into various products such as packages. For example, vinyl chloride film is used for packages (squeeze packages) such as pharmaceuticals (tablets). Another example is the use of polypropylene film when packaging content that requires moisture resistance. In recent years, from the viewpoint of maintaining the quality of the contents, in order to impart more excellent gas barrier properties or moisture resistance, a laminate in which a resin film is laminated with a metal foil is used. For example, a laminate composed of base material layer (resin film)/metal foil layer (aluminum foil)/sealing layer is known.

In the industrial field, the exterior material of lithium-ion batteries has been the mainstream since the metal can type in the past, but it has been pointed out that it has shortcomings such as low degree of freedom in shape and difficulty in reducing weight. Therefore, there are proposals to use a laminate consisting of base layer/metal foil layer/sealing layer or a laminate consisting of base layer/base layer/metal foil layer/sealing layer as the exterior body. Compared with metal cans, the laminate is flexible and has a high degree of freedom in shape, can be reduced in weight by thinning, and can be easily miniaturized, so it is widely used.

There are various requirements for laminates used in the above-mentioned applications, and moisture resistance is a very important factor among them. However, metal foils such as aluminum foil that can impart moisture resistance lack ductility and poor formability as a single body. Therefore, using a polyamide-based film as the resin film constituting the base material layer can impart ductility and improve moldability.

The formability mentioned here means especially the formability at the time of cold-forming (cold working) a film. That is, when molding a film to manufacture a product, the molding conditions include: a) thermoforming by melting the resin under heating, and b) cold molding in which the resin is formed in a solid state without melting the resin, and in the above-mentioned applications Above all, the formability of cold forming (especially drawing processing and stretching processing) is required. Cold forming is a molding method that is better in production speed and economical cost because there is no heating step, and it is more advantageous than thermoforming in preventing resin denaturation. Therefore, polyamide-based films are also continuously being developed for cold forming.

As the polyamide-based film, stretched polyamide-based films are known (for example, Patent Documents 1 to 2). However, these polyamide-based films are stretched by blown film stretching. That is, not only the productivity is low, but also the obtained stretched film is insufficient in terms of thickness uniformity, dimensional stability, and the like. Especially when the thickness of the film is not uniform, when cold forming is used to process the laminate formed of the film and metal foil, there is a risk of fatal defects such as breakage of the metal foil and generation of holes.

In this regard, a polyamide-based film stretched by a tenter method has been proposed (for example, Patent Documents 3 to 10). The tenter method is more advantageous than the blown film stretching method in terms of productivity, dimensional stability, and the like.

However, even the polyamide-based film stretched by the tenter method still has the problem of uneven physical properties (anisotropy) in all directions of the film. Therefore, it is difficult to say that the moldability in cold forming (particularly deep drawing) has sufficient performance.

The polyamide-based film 14 is produced by the steps shown in FIG. 1 . First, the raw material 11 is melted in the melt-kneading step 11 a to prepare a melt-kneaded product 12 . The melt-kneaded product 12 is formed into a sheet by a forming step 12a to obtain an unstretched sheet 13 . Next, the unstretched sheet 13 is biaxially stretched in the stretching step 13 a to obtain a polyamide-based film 14 . Then, after the stretched polyamide-based film 14 passes through the lamination step 14a of sequentially laminating the metal foil layer 15 and the sealing film 16 to obtain the laminate 17, the laminate is formed in the cold forming step 15a during secondary processing. 17 is processed into a predetermined shape to produce various products 18 (for example, containers, etc.).

For the stretched polyamide-based film 14, it is expected to reduce the unevenness of physical properties in all directions on the plane, and it is preferable to reduce at least 4 directions every 90 degrees (based on any direction (0 degrees), clockwise relative to this direction) 45 degrees, 90 degrees and 135 degrees total 4 directions) uneven physical properties. For example, as shown in FIG. 4, a biaxially stretched polyamide-based film is centered at an arbitrary point A, and when the MD (film flow direction) during biaxial stretching is taken as the reference direction (direction of 0 degrees), it is expected that Decrease (a) reference direction (0-degree direction), (b) 45-degree clockwise direction relative to MD (hereinafter referred to as "45-degree direction"), (c) 90-degree clockwise direction relative to MD (TD: parallel to the film flow direction) Right angle direction) (hereinafter referred to as "90-degree direction") and (d) 4 directions of physical property unevenness in the clockwise 135-degree direction relative to MD (hereinafter referred to as "135-degree direction").

When the laminate 17 containing the stretched polyamide-based film 14 is supplied to the cold forming step 15a, the polyamide-based film 14 will be stretched in all directions, so when the polyamide-based film 14 is stretched in the aforementioned four directions, When the physical properties are uneven, it is difficult to stretch uniformly in all directions during cold forming. That is, since there will be directions that are easy to stretch and directions that are not suitable for stretching, breakage, delamination or holes in the metal foil will occur. On the other hand, when such a problem occurs, it is difficult to perform the function of the package, and there is a risk of damage to the packaged body (content). Therefore, it is necessary to reduce the unevenness of physical properties in all directions as much as possible.

In this case, one of the physical properties that affect the formability during cold forming is the film thickness. When cold-forming a laminate containing a polyamide-based film with uneven film thickness, the thinner part of the film will be broken to generate holes, or the possibility of delamination will increase. Therefore, the polyamide-based film used for cold forming must control the uniform thickness of the film as a whole.

Here, in terms of the thickness uniformity of the polyamide-based film, although stretching by the tenter method is better than the blown film stretching method, the polyamide-based film obtained from the above-mentioned patent documents 3-10 The thickness accuracy is still insufficient. That is to say, during cold forming, as mentioned above, it is necessary to extend uniformly in four directions vertically, horizontally and obliquely, so it is necessary to have sufficient thickness uniformity for cold forming. In particular, the thinner the film thickness (especially below 15 μm), the more significant the effect of thickness uniformity on formability.

Generally speaking, the thicker the thickness, the more uniform the thickness of the film can be ensured, so in order to ensure the uniform thickness, it is also designed to be thicker. However, in recent years, polyamide-based films and their laminates for cold forming have gradually been widely used as exterior materials for lithium-ion batteries. etc., it is desired to reduce the thickness of the polyamide-based film. However, if the thickness is reduced, it will be difficult to ensure the exact thickness uniformity.

As described above, the development of a thin polyamide-based film with excellent thickness uniformity and less unevenness in physical properties in the aforementioned four directions has been urgently desired, but such a film has not yet been developed.

On the other hand, when a polyamide-based film is used as an exterior material for a lithium-ion secondary battery, in addition to the above-mentioned physical properties, it is also required to have the characteristic of electrolyte solution resistance. For example, the polyamide-based film is used in the form of a laminate consisting of "substrate layer (polyamide-based film)/metal foil layer/sealing layer". Then, the laminate was processed into a container shape so that the base layer side was on the outside of the battery and the sealing layer was on the inside (inside of the battery), and then the battery electrolyte was poured into the inside of the exterior material (inside of the container).

When manufacturing this lithium ion secondary battery, during the step of injecting the electrolyte solution into the container, or the step of heat-sealing the exterior material to make it airtight after the injection, the electrolyte solution may leak and adhere to the outside of the exterior material. (That is, the problem of polyamide-based film. When the polyamide-based film is attached to the electrolyte, the polyamide-based film will deteriorate due to whitening, decomposition reactions, etc., resulting in poor appearance or the need for external materials for lithium-ion secondary batteries. Therefore, the polyamide-based film is required to have resistance to the electrolyte (electrolyte resistance).

On the other hand, in order to improve the electrolytic solution resistance, it is proposed to provide a protective layer having electrolytic solution resistance on the outer side of the base material layer. For example, it is proposed to use a polyethylene terephthalate resin film as an exterior material for a protective layer (Patent Document 11), and an exterior material using a film stretched from a laminate of a polyester film and a polyamide film (Patent Document 11). 12) For the protective layer, an exterior material using a coating layer made of a specific resin (Patent Document 13) and the like.

However, these exterior materials have other points that need to be improved. For example, the exterior material of Patent Document 11 is laminated with a polyethylene terephthalate resin film, resulting in an increase in the weight per unit area of the film, which cannot fully meet the recent demand for lightweight batteries. In addition, there is a possibility that formability may be lowered due to the lamination of the above-mentioned films. Moreover, in the manufacturing steps, it is necessary to carry out the step of setting the adhesive agent and the step of layering the polyethylene terephthalate resin film, so the processing is complicated and the cost is high.

In Patent Document 12, the stretched laminate of polyester film and polyamide film reduces the ratio of the polyamide layer, and has the problem that the strength of the exterior material decreases compared with a polyamide film of the same thickness.

In Patent Document 13, although a coating layer made of resin such as polyvinylidene chloride and urethane resin is used for the protective layer, the performance of electrolyte resistance is still not sufficient for the protective layer.

Prior Art Documents Patent Documents Patent Document 1: Japanese Patent No. 5487485 Patent Document 2: Japanese Patent No. 5226942 Patent Document 3: Japanese Patent No. 5467387 Patent Document 4: Japanese Patent Laid-Open No. 2011-162702 Patent Document 5: Japanese Patent Laid-Open 2011-255931 Patent Document 6: Japanese Patent Laid-Open No. 2013-189614 Patent Document 7: Japanese Patent No. 5226941 Patent Document 8: Japanese Patent Laid-Open No. 2013-22773 Patent Document 9: International Publication WO2014/084248 Patent Document 10: Japan Patent No. 3671978 Patent Document 11: Japanese Patent Laid-Open No. 2002-56824 Patent Document 12: Japanese Patent Laid-Open No. 2013-240938 Patent Document 13: Japanese Patent Laid-Open No. 2000-123799

Summary of the Invention Problems to be Solved by the Invention Therefore, the main object of the present invention is to provide a polyamide-based film that is excellent in thickness uniformity, can effectively suppress the unevenness of physical properties in the above four directions, and is also excellent in resistance to electrolyte solutions.

Means for Solving the Problems The present inventors, in view of the problems of the conventional technology, have made repeated efforts to study and found that the above object can be achieved based on the knowledge that a polyamide-based thin film with specific physical properties can be produced by using a specific manufacturing method, and thus completed the present invention. .

That is, the present invention relates to the following polyamide-based film, a laminate and container using the same, and a method for producing the same. 1. A polyamide-based film comprising a polyamide-based substrate layer and a protective layer formed on at least one side of the substrate layer. The polyamide-based film is characterized in that: (1) the aforementioned protective layer contains ethylene-containing The vinyl alcohol-based polymer (A) of alcohol unit and the vinyl-based polymer (B) containing unsaturated carboxylic acid unit (but, the aforementioned vinyl alcohol-based polymer (A) is not included); (2) the aforementioned film is as follows: (2-1) Counting from any point in the aforementioned film, when the specific direction is 0°, 45°, 90°, and 135° clockwise relative to the direction, a total of 4 directions, when the uniaxial tensile test causes 5% elongation The difference between the maximum value and the minimum value of each stress is 35MPa or less; and (2-2) in the above-mentioned 4 directions, the difference between the maximum value and the minimum value of each stress at 15% elongation caused by uniaxial tensile test is 40MPa or less . 2. The polyamide-based film according to item 1 above, wherein the unsaturated carboxylic acid unit contains at least one maleic acid-based unit among maleic acid and maleic anhydride units. 3. The polyamide-based film according to item 1 above, wherein the aforementioned protective layer is as follows: (3-1) The vinyl alcohol unit content in the vinyl alcohol-based polymer (A) is 40 mol% or more; (3-2) The unsaturated carboxylic acid unit content in the vinyl polymer (B) is 10 mol % or more. 4. The polyamide-based film according to item 1 above, wherein the molar ratio of vinyl alcohol units to unsaturated carboxylic acid units (vinyl alcohol units/unsaturated carboxylic acid units) in the protective layer is 1/99 to 60/40 . 5. The polyamide-based film according to claim 1 or 2, wherein counting from any point in the aforementioned film, taking a specific direction as 0 degrees, clockwise 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees relative to the direction , 270 degrees and 315 degrees in total 8 directions thickness standard deviation is 0.200μm or less. 6. The polyamide-based film according to item 1 above, which has an average thickness of 16 μm or less. 7. The polyamide-based film according to item 1 above, wherein at least one surface has a dynamic friction coefficient of 0.60 or less. 8. A laminate comprising the polyamide-based film according to any one of items 1 to 7 above and a metal foil laminated on the film. 9. A container comprising the laminate according to item 8 above. 10. A method for producing a polyamide-based film, which is a method for producing a film comprising a polyamide-based substrate layer and a protective layer formed on at least one side of the substrate layer, the method is characterized in that it includes the following steps : (1) The sheet step of forming the melt-kneaded material containing polyamide resin into a sheet to obtain an unstretched sheet; (2) Biaxially stretching the aforementioned unstretched sheet to MD and TD sequentially or simultaneously And the step of making a stretched film; wherein, (3) satisfy both the following formulas a) and b): a) 0.85≦X/Y≦0.95 b) 8.5≦X×Y≦9.5 (only, X represents the aforementioned MD , Y represents the elongation ratio of the aforementioned TD); and, the aforementioned manufacturing method comprises the following steps: (4) on at least one side of a) an unstretched sheet or b) a film stretched in at least one direction of MD and TD Above, a step of applying a coating liquid containing a vinyl alcohol-based polymer (A) containing a vinyl alcohol unit and a vinyl-based polymer (B) containing an unsaturated carboxylic acid unit.

Effects of the Invention The polyamide-based film of the present invention has excellent thickness uniformity and excellent stress balance when elongated in four directions consisting of 0° direction, 45° direction, 90° direction and 135° direction. Therefore, for example, the metal foil of the laminate formed by laminating the film and metal foil of the present invention has good ductility, so when cold forming is used for stretch forming (especially deep drawing forming or stretch forming), it can effectively inhibit or prevent metal foil from forming. Fracture, delamination, generation of holes, etc., to produce high-quality products (formed bodies) with high reliability.

In particular, even if the polyamide-based film of the present invention is extremely thin, for example, about 15 μm or less in thickness, it has excellent stress balance and excellent thickness uniformity when stretched in the aforementioned four directions. Therefore, the laminate formed by laminating the film and the metal foil can be cold-formed to produce a higher-output and miniaturized product, which is also beneficial to economical costs.

In addition, the polyamide-based thin film of the present invention can also exhibit excellent electrolyte solution resistance. That is, since it has a protective layer containing a specific polymer, it is possible to suppress or prevent deterioration of the film even if the electrolyte solution adheres. Therefore, for example, it can be applied to the use of a lithium ion secondary battery exterior material. This also contributes to providing a highly reliable battery.

Modes for Carrying Out the Invention 1. Polyamide-based film The polyamide-based film of the present invention (hereinafter referred to as "the film of the present invention") comprises a polyamide-based substrate layer and a protective film formed on at least one side of the substrate layer. layer, the polyamide film is characterized in that: (1) the aforementioned protective layer contains a vinyl alcohol polymer (A) containing vinyl alcohol units and a vinyl polymer (B) containing unsaturated carboxylic acid units (except , does not include the aforementioned vinyl alcohol-based polymer (A)); (2) The aforementioned film is as follows: (2-1) Counting from any point in the aforementioned film, taking a specific direction as 0 degrees, 45 degrees clockwise relative to the direction, In the 4 directions of 90 degrees and 135 degrees, the difference between the maximum value and the minimum value of each stress at 5% elongation caused by the uniaxial tensile test is 35MPa or less; and (2-2) in the aforementioned 4 directions, the uniaxial The difference between the maximum value and the minimum value of each stress when the tensile test causes 15% elongation is 40MPa or less.

(A) The material of the film of the present invention, the material constituting the polyamide-based substrate layer, and the composition of the polyamide-based substrate layer, as long as the main component is a layer of polyamide resin, especially polyamide-containing resin can be suitably used The thin film is used as the substrate layer. Polyamide resin is a polymer composed of multiple monomers bonded by amide. Representative examples thereof include 6-nylon, 6,6-nylon, 6,10-nylon, 11-nylon, 12-nylon, poly(m-xylylene adipamide), and the like. In addition, the polyamide can also be, for example, 6-nylon/6,6-nylon, 6-nylon/6,10-nylon, 6-nylon/11-nylon, 6-nylon/12-nylon Two or more copolymers such as nylon. And it may also be a mixture of these. Among the above, a) a homopolymer of 6-nylon, b) a copolymer containing 6-nylon, or c) a mixture thereof is preferable from the standpoint of cold formability, strength, and economic cost.

The number average molecular weight of the polyamide resin is not particularly limited, and can be changed according to the type of polyamide resin used, etc., but it is generally about 10,000-40,000, preferably 15,000-25,000. The use of polyamide resins within the above-mentioned range facilitates stretching at relatively low temperatures, so problems such as crystallization and lowering of cold formability caused by stretching at higher temperatures can be more reliably avoided.

The content of the polyamide resin in the polyamide base material layer is generally 90-100% by mass or more, preferably 95-100% by mass, and more preferably 98-100% by mass. That is, components other than the polyamide resin may be contained as needed within a range that does not inhibit the effects of the present invention. For example, in addition to polyolefins, polyamide elastomers, polyester elastomers and other bending resistance modifiers, one or more pigments, antioxidants, UV absorbers, preservatives, and antistatic agents can also be added. various additives such as additives, inorganic particles, etc. In addition, the slip agent for imparting slipperiness may contain at least one of various inorganic slip agents and organic slip agents. The method of adding such lubricants (particles) may be, for example, a method of adding particles in the polyamide resin as a raw material, a method of directly adding them to an extruder, etc., either method may be used, or 2 may be used in combination. the above methods.

(B) Protective layer The film of the present invention has a protective layer on at least one side of the polyamide base layer. In particular, a protective layer is formed directly adjacent to the polyamide base material layer. In the present invention, as will be described later, the protective layer is preferably a coating layer formed from a coating liquid from the viewpoint of adhesion to the substrate layer and the like.

The protective layer contains a vinyl alcohol-based polymer (A) containing vinyl alcohol units (hereinafter, also referred to as "component A" unless otherwise specified) and a vinyl-based polymer (B) containing unsaturated carboxylic acid units (hereinafter, as long as It is also referred to as "component B" if there is no particular limitation) (however, the above-mentioned vinyl alcohol-based polymer (A) is not included).

The total amount of component A and component B in the protective layer is not particularly limited, but is generally about 80-100% by mass, preferably 85-98% by mass, and more preferably 90-98% by mass. That is, the protective layer may contain components other than A component and B component within the range which does not inhibit the effect of this invention. For example, one kind or two or more kinds of various additives as described below may be added.

Component A Component A is a vinyl alcohol-based polymer containing a vinyl alcohol unit -[CH ₂ CH(OH)]-. In addition to the homopolymer substantially composed only of vinyl alcohol units, the polymer may also be a copolymer of vinyl alcohol units and other monomer units. Moreover, what chemically modified part of the vinyl alcohol unit other than the hydroxyl group can also be used. The most suitable example of the component A is the above-mentioned homopolymer (namely, polyvinyl alcohol). All of these can use known or commercially available ones.

The above-mentioned homopolymer can be obtained by completely saponifying or partially saponifying a carboxylate polymer of vinyl alcohol. Examples of the above-mentioned esters include vinyl formate, vinyl acetate, vinyl propionate, trimethyl vinyl acetate, vinyl neodecanoate, etc. Among them, vinyl acetate is suitable for industrial use.

In addition, the above-mentioned copolymer can be obtained by completely saponifying or partially saponifying a copolymer of a carboxylate of vinyl alcohol and other vinyl monomers. Other vinyl monomers that can be copolymerized with the above-mentioned esters include unsaturated monocarboxylic acids such as crotonic acid, acrylic acid, and methacrylic acid and their derivatives; unsaturated sulfonic acids such as maleic acid, itaconic acid, and fumaric acid; and Its derivatives: olefins with 2 to 30 carbons, alkyl vinyl ethers with 2 to 30 carbons, vinylpyrrolidones with 2 to 30 carbons, etc. In addition, the aforementioned derivatives are especially preferably esters, salts, acid anhydrides, amides or nitrile compounds.

The degree of saponification of the above-mentioned polymers or copolymers is generally set at 70 mol% or more, especially 90 mol% or more, and it is more effective in improving the electrolyte resistance if it is set at 98 mol% or more. good. Therefore, for example, a polymer or copolymer having a degree of saponification of 95 to 100 mol % can be suitably used. Also, the saponification method is not particularly limited as long as the vinyl ester moiety can be converted into vinyl alcohol units, and known alkali saponification methods and acid saponification methods can be suitably used.

The content of the vinyl alcohol unit of component A is preferably more than 40 mol%, especially more than 60 mol%. Thereby, the hydroxyl group (OH group) of the vinyl alcohol unit can effectively function as a reactive group that reacts with the B component to form a crosslinked structure. As a result, higher electrolyte solution resistance and the like can be exhibited.

In addition, in this invention, content of a vinyl alcohol unit shows the total amount of the vinyl alcohol unit which contributes to the formation of the said crosslinked structure, and the vinyl alcohol unit which does not contribute to formation of the said crosslinked structure.

Component B The component B is a vinyl polymer (B) containing an unsaturated carboxylic acid unit (however, the aforementioned vinyl alcohol polymer (A) is not included). In addition to the polymer consisting substantially only of unsaturated carboxylic acid units, copolymers of unsaturated carboxylic acid units and monomer units other than unsaturated carboxylic acid units may be mentioned. Moreover, what chemically modified a part other than the carboxyl group of an unsaturated carboxylic acid unit can also be used. All of these can use known or commercially available ones.

Unsaturated carboxylic acid units such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, ornithic acid, orionic anhydride, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, In addition to allyl succinic acid and the like, compounds having at least one carboxyl group or acid anhydride group in the molecule (in the monomer unit) such as half esters of unsaturated dicarboxylic acids and half amides can also be used. Among them, maleic acid and/or maleic anhydride are preferably used as unsaturated carboxylic acid units from the viewpoint of obtaining higher electrolyte solution resistance and the like.

In addition to the homopolymers (component B1) composed of the same unsaturated carboxylic acid units, the above-mentioned polymers substantially composed of unsaturated carboxylic acid units can also include two or more different types of unsaturated carboxylic acid units. Copolymer (B2 component). As B1 component or B2 component, polyacrylic acid etc. can be used suitably, for example.

As the copolymer (component B3) of an unsaturated carboxylic acid unit and a monomer unit other than the unsaturated carboxylic acid unit shown above, a copolymer of an unsaturated carboxylic acid and an olefin can be used suitably. Examples of olefins include ethylene, propylene, 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-hexene, 1-octene, etc. . Therefore, for example, an olefin-maleic acid copolymer can be suitably used. In particular, ethylene-maleic acid copolymer (EMA) is used.

The olefin-maleic acid copolymer (especially EMA) itself can also be prepared according to known production methods. For example, it can be produced by polymerizing maleic anhydride and olefins (ethylene, etc.) according to a polymerization method such as solution radical polymerization. Moreover, EMA etc. can also use a commercial item. Incidentally, the maleic acid unit in the olefin-maleic acid copolymer tends to form a maleic anhydride structure in which the adjacent carboxyl group has been cyclized and dehydrated in a dry state, but it will open to form a maleic anhydride structure when it is wet or in an aqueous solution. To acid structure. Therefore, unless otherwise specified in the present invention, the maleic acid unit and the maleic anhydride unit are collectively referred to as "maleic acid-based units". In the present invention, as mentioned above, the unsaturated carboxylic acid units preferably contain maleic acid units.

In addition, in the present invention, regarding the above-mentioned B3 component, the copolymer containing an unsaturated carboxylic acid unit and a vinyl alcohol unit in the molecule is treated as the A component in the present invention.

The content of unsaturated carboxylic acid units in component B will vary depending on the type of unsaturated carboxylic acid units used, etc., but generally set it to 10 mol% or more, especially 20 mol% or more, and set it to 30 mol%. Mole % or more is more preferable, and it is most preferably set as 35 Mole % or more. Therefore, when maleic acid and/or maleic anhydride units are used as unsaturated carboxylic acid units, it is generally set at 10 mol% or more, especially 20 mol% or more, and more preferably 30 mol% or more. Good, set as the best above 35 mol%. Therefore, a part or all of the carboxyl groups of the unsaturated carboxylic acid unit can react with a part or all of the hydroxyl groups of the component A to form a crosslinked structure, resulting in better electrolyte solution resistance. The upper limit of the above content is not particularly limited, generally about 60 mol%.

In addition, in this invention, content of an unsaturated carboxylic acid unit shows the total amount of the unsaturated carboxylic acid unit which contributes to the said crosslinked structure, and the unsaturated carboxylic acid unit which does not contribute to formation of the said crosslinked structure.

Also, the weight average molecular weight of component B, especially EMA, is not particularly limited, but is preferably 1,000 to 1,000,000, more preferably 3,000 to 500,000, more preferably 7,000 to 300,000 from the viewpoint of obtaining higher electrolyte resistance, 10,000-200,000 is preferred.

In the present invention, the ratio of component A to component B is not particularly limited, but it is preferably 1/99 to 60 based on the molar ratio of the aforementioned vinyl alcohol unit to the unsaturated carboxylic acid unit (vinyl alcohol unit/unsaturated carboxylic acid unit). The range of /40 is blended with two components, and the range of 20/80 to 50/50 is preferable. If the molar ratio exceeds this range, it will be difficult to obtain an effective crosslinking density capable of exhibiting the electrolyte solution resistance of the thin film.

As mentioned above, the protective layer may also contain components other than components A and B, but it is particularly preferable to contain at least one of an inorganic lubricant and an organic lubricant. By making the protective layer contain these lubricants, the coefficient of dynamic friction can be controlled in an optimum range, and the smoothness of the film of the present invention can be improved more effectively.

Especially for the film of the present invention, it is better to set the side of the protective layer as the surface that is in contact with the mold during molding, and it is preferable to have slipperiness (low coefficient of dynamic friction). For example, when the film of the present invention is used as the outermost laminate for cold forming, because the film of the present invention will be in contact with the forming die, if the film of the present invention is not easy to slide (that is, the coefficient of friction is large), the forming die will contain the present invention when it is pressed. Wrinkles are generated on the surface of the film laminate, or the possibility of delamination of the laminate is increased. Furthermore, it is difficult to uniformly shape the entire laminated body, and there is a possibility that voids may be generated. Therefore, by making the protective layer laminated on the surface of the film of the present invention in contact with the molding die contain at least one of an inorganic lubricant and an organic lubricant, higher smoothness can be imparted, and as a result, delamination, holes, etc. can be prevented in advance. occur. Based on these findings, it is desirable to make the protective layer contain a predetermined amount of a predetermined organic or inorganic lubricant as shown below.

Organic lubricant The organic lubricant is not particularly limited. For example, in addition to various organic lubricants such as hydrocarbon-based, fatty acid-based, aliphatic bisamide-based, and metal soap-based, phenol resins, melamine resins, and polymethylmethacrylates can also be used. Resin-based organic lubricants such as ester resins. In the present invention, it is especially suitable to use an organic slip agent (for example, with a melting point below 150° C.) that can melt and knead with the polyamide resin component, and the organic slip agent can be suitable for aliphatic bisamide-based slip agents and the like.

The content of the organic slip agent in the protective layer of the polyamide-based film of the present invention is generally preferably 0.02-0.25% by mass, preferably 0.03-0.15% by mass. When the content of the organic slip agent is less than 0.02% by mass, the effect of improving the smoothness may not be sufficiently obtained. On the other hand, when the organic slip agent content exceeds 0.25% by mass, too much organic slip agent will flow out of the film surface, resulting in a decrease in the adhesiveness of the adhesive and printing ink, and the adhesive force with the adhesive will decrease or the printing ink will be reduced during lamination. Defective, especially when the adhesive force is reduced, the cold formability may be reduced. Therefore, in the present invention, it is especially desirable to set the above-mentioned organic slip agent content to the total content of at least one type of aliphatic bisamide-based slip agents.

Inorganic slip agent (A) In the present invention, the inorganic slip agent can include, for example, silicon dioxide, clay, talc, mica, calcium carbonate, zinc carbonate, wollastonite, aluminum oxide, magnesium oxide, calcium silicate, sodium aluminate, Calcium aluminate, magnesium aluminosilicate, zinc oxide, antimony trioxide, zeolite, kaolinite, hydrotalcite, oxide glass, etc. Among them, silicon dioxide (silicon oxide) is particularly preferable.

Inorganic lubricants are generally in powder form, and their average particle size should generally be 0.5-4.0 μm. When the average particle diameter is less than 0.5 μm, the effect of roughening the surface of the film is small, and the effect of improving smoothness cannot be sufficiently obtained. On the other hand, when the average particle diameter exceeds 4.0 micrometers, there exists a possibility that transparency may deteriorate.

The particle shape of the inorganic lubricant is not particularly limited, and may be, for example, any of spherical, flake-like, indeterminate, balloon-like (hollow), and the like. Therefore, the present invention can also use, for example, glass beads, glass balloons, and the like.

The content of the inorganic lubricant in the polyamide film of the present invention is generally preferably 0.05-30% by mass, preferably 0.1-15% by mass, especially preferably 0.1-10% by mass. If the content of the inorganic lubricant is less than 0.05% by mass, the effect of improving the smoothness by adding the inorganic lubricant may not be sufficiently obtained. On the other hand, if the content of the inorganic lubricant exceeds 30% by mass, the surface of the film becomes too rough, resulting in reduced ink adhesion, or loss of transparency of the film, and it may be difficult to impart originality by printing. In addition, there are also things that are prone to curling when manufacturing films.

In the present invention, the thickness of the protective layer can be appropriately set according to the application and purpose of use of the polyamide-based film of the present invention. For example, when a polyamide-based film is used as a battery exterior material, in order to protect the substrate layer from electrolyte damage and improve the electrolyte resistance of the film, it is generally more than 0.05 μm, preferably 0.1 to 2.0 μm , especially 0.1 ~ 1.0μm is the best. Regarding the formation method of the protective layer, when using a coating step between MD stretching and TD stretching as described later (that is, when performing continuous coating), the thickness of the protective layer is preferably 0.1 to 1.0 μm.

(C) Physical properties of the film of the present invention The film of the present invention (especially the polyamide-based substrate layer) is preferably one in which molecules are oriented biaxially. The films are basically obtainable by biaxial stretching. It is especially suitable for biaxially stretched films using rolls and tenters.

(C-1) Stress characteristics The film of the present invention must satisfy the above-mentioned A and B values at the same time as an indicator of the excellent stress balance during elongation during secondary processing. If the above-mentioned A and B values exceed the above-mentioned ranges, the stress balance in the entire direction of the polyamide-based film will be poor, making it difficult to obtain uniform moldability. If uniform formability cannot be obtained, for example, when cold-forming a laminate obtained by laminating the film and metal foil of the present invention, sufficient ductility cannot be imparted to the metal foil (that is, the polyamide-based film becomes less likely to follow the metal foil). ), so the metal foil will break, or defects such as delamination and holes will easily occur.

The aforementioned A value is generally below 35MPa, especially preferably below 30MPa, preferably below 25MPa, most preferably below 20MPa. In addition, the lower limit value of the aforementioned A value is not particularly limited, and is generally about 15 MPa.

The aforementioned B value is generally below 40MPa, especially preferably below 38MPa, preferably below 34MPa, most preferably below 30MPa. In addition, the lower limit of the aforementioned B value is not particularly limited, and is generally about 20 MPa.

Also, the stresses in the aforementioned four directions at 5% elongation are not particularly limited, but from the standpoint of cold formability of the laminate, all are preferably in the range of 35-130 MPa, and preferably in the range of 40-90 MPa. Among them, the range of 45~75MPa is the best.

The stresses at 15% elongation in the aforementioned four directions are not particularly limited. From the standpoint of the cold formability of the laminate, all are preferably in the range of 55~145MPa, and preferably in the range of 60~130MPa. Among them, The range of 65~115MPa is the best.

If the stresses at the 5% and 15% elongation in the four directions of the film of the present invention do not satisfy the above ranges, sufficient cold formability may not be obtained.

The stresses in the aforementioned four directions of the film of the present invention are measured as follows. First, after conditioning the polyamide film at 23°C×50%RH for 2 hours, take any position on the film as the center point A as shown in Figure 5, and arbitrarily specify the reference direction (0 degree direction) of the film, and Let the 45-degree direction (b), 90-degree direction (c) and 135-degree direction (d) clockwise from the reference direction (a) be the measurement direction, and cut out the distance from the center point A for each measurement direction 100mm and a short strip sample with a distance of 15mm in the direction perpendicular to the measuring direction.

For example, as shown in FIG. 5 , a sample 41 (100 mm in length x 15 mm in width) is cut from the center point A at a distance of 30 mm to 130 mm in the direction of 0°. Samples are also cut in the same way in other directions. Using a tensile testing machine (AG-1S manufactured by Shimadzu Corporation) equipped with a 50N measuring load cell and a sample chuck, at a tensile speed of 100mm/min, measure the elongation of these samples at 5% and 15% respectively. time stress. In addition, when the above-mentioned reference direction can be determined as the MD of the stretching step during film production, the MD is taken as the reference direction.

The polyamide-based film of the present invention satisfying the above characteristic values is preferably produced by a biaxial stretching method including stretching in at least one of the longitudinal direction and the transverse direction using a tenter.

Generally, the biaxial stretching method includes a simultaneous biaxial stretching method in which stretching steps in the longitudinal direction and a transverse direction are simultaneously performed, and a sequential biaxial stretching method in which stretching steps in the longitudinal direction are performed followed by a transverse stretching step. In addition, although the foregoing description is based on the example that the vertical direction is carried out first, the present invention may be carried out regardless of whether the vertical direction or the horizontal direction is carried out first.

In view of the degree of freedom in setting stretching conditions, etc., the film of the present invention is preferably produced by a sequential biaxial stretching method. Therefore, the film of the present invention is preferably produced by sequential biaxial stretching using a step of stretching in at least one direction including the longitudinal direction and the transverse direction using a tenter frame. The thin film of the present invention is preferably produced by the production method of the present invention described below.

(C-2) Average thickness and thickness accuracy The index of the very high thickness accuracy (thickness uniformity) of the film of the present invention is that the standard deviation of the thickness in 8 directions shown below is 0.200 μm or less, preferably 0.180 μm or less, and More preferably, it is 0.160 μm or less. If the standard deviation of the above-mentioned thickness accuracy is less than 0.200 μm, the surface thickness unevenness of the film is very small. For example, even if the film thickness is less than 15 μm, the laminate obtained by laminating with metal foil has good formability. If the standard deviation exceeds 0.200μm, the thickness accuracy is low, especially when the film thickness is small, when it is laminated with metal foil, it cannot be endowed with gold. It will not have defects such as delamination and holes after deep drawing and cold forming. Foil has sufficient ductility, but delamination or voids may become apparent, and good formability may not be obtained.

The evaluation method of the above thickness accuracy is to adjust the humidity of the polyamide film at 23℃×50%RH for 2 hours, as shown in Figure 6, take any position on the film as the center point A, and specify the reference direction (0 degree direction ), counting from the center point A toward the reference direction (a), clockwise to the reference direction at 45 degrees (b), at 90 degrees (c), at 135 degrees (d), at 180 degrees (e), and at 225 degrees Eight directions of 100mm straight lines L1~L8 are drawn in the direction (f), 270-degree direction (g) and 315-degree direction (h) respectively. Then, the thickness was measured at intervals of 10 mm from the center point on each straight line using a length gauge "HEIDENHAIN-METRO MT1287" (manufactured by HEIDENHAIN Co., Ltd.) (measurement at 10 points). Fig. 6 shows an example of the state of obtaining measurement points (10 points) when measuring L2 in the 45-degree direction. Then, the average value of the measurement values of 80 points of the measured data was calculated on all the straight lines, and this was regarded as the average thickness, and the standard deviation value relative to the average thickness was calculated. In addition, when the above-mentioned reference direction can be determined as the MD of the stretching step during film production, the MD can be used as the reference direction.

In the present invention, the average thickness and standard deviation can be based on point A at any point of the polyamide-based film, especially the following three points of the polyamide-based film that is expected to be rolled on a film roll Any point is the average thickness and standard deviation within the above range. The 3 points are a) a position near the center of the roll width and half of the roll amount, b) a position near the right end of the roll width and half the roll amount, and c) a position near the left end of the roll width and near the end of the curl.

In addition, the average thickness of the film of the present invention is preferably 30 μm or less, preferably 26 μm or less, more preferably 16 μm or less, more preferably 15.2 μm or less, preferably 13 μm or less, most preferably 12.2 μm or less.

The film of the present invention is preferably made into a laminate that can be laminated with metal foil, and is suitable for cold forming. By performing biaxial stretching using a tenter machine as described below under the stretching conditions that meet specific conditions, even the thickness Small films can also be produced that have excellent stress balance in the aforementioned four directions during elongation, and have very high thickness accuracy (thickness uniformity) in the aforementioned four directions.

If the average thickness of the film exceeds 30 μm, the formability of the polyamide-based film itself will decrease, and it may be difficult to use it as a small battery exterior material, and it may also be disadvantageous in terms of economic cost. On the other hand, the lower limit of the film thickness is not particularly limited. When the average thickness is less than 2 μm, the ductility imparted to the metal foil when it is bonded to the metal foil is likely to be insufficient, and the moldability may be poor, so it is generally set at about 2 μm. That's it.

The polyamide-based film of the present invention is laminated with metal foil to form a laminate, which is suitable for cold forming applications. Using the polyamide-based film of the present invention that satisfies the above characteristics can impart sufficient ductility to the metal foil. By this effect, formability can be improved during cold forming (including drawing forming (especially deep drawing forming), etc., metal foil can be prevented from breaking, and defects such as delamination and holes can be suppressed or prevented.

The smaller the thickness of the polyamide-based film, the more difficult it is to impart sufficient ductility to the metal foil. Especially for very thin films below 20μm, the stress during elongation will be uneven, resulting in a decrease in thickness accuracy, so the polyamide film or metal foil will be significantly broken due to the pressing force during cold forming. In other words, the thinner the film is, the greater the stress unevenness is when stretched, and the thickness unevenness also becomes larger, so a higher degree of control is required.

In this case, according to the general blown film stretching method for manufacturing polyamide-based films or the known manufacturing method using the tenter method, the thickness should be less than 15 μm, and the stress unevenness during elongation should be small. It is very difficult for those with high thickness accuracy. This fact can be clearly seen, for example, in any of Patent Documents 1 to 10, which only disclose that the polyamide-based films of specific examples have a thickness of at least 15 μm.

On the other hand, the present invention adopts the specific manufacturing method described below, and can successfully provide a polyamide having excellent stress balance during elongation in the above four directions and high thickness uniformity even if the thickness is 16 μm or less. Amine film. Since the above-mentioned special polyamide-based film can be provided, when the laminated body laminated with metal foil is used, for example, as an exterior body of a battery (such as a lithium-ion battery), for example, the number of electrodes and the electrolyte can be increased. In addition to the same capacity, it also helps the miniaturization and low economic cost of the battery itself.

(C-3) Coefficient of dynamic friction (smoothness) The index of the film of the present invention that can exhibit excellent formability (smoothness) during cold forming is to make the coefficient of dynamic friction of at least one surface be 0.60 or less, preferably 0.55 or less, especially preferably 0.50 or less. By controlling the coefficient of dynamic friction below 0.60, even when cold forming is performed in a high-humidity environment (such as a humidity above 90%), its smoothness is also good, and it can effectively suppress or prevent such as wrinkles, delamination, holes etc. If the dynamic friction coefficient is more than 0.60, wrinkles or delamination may be caused especially when cold forming is performed in a high-humidity environment. Furthermore, it is difficult to uniformly shape the entire laminated body, and holes and the like are likely to occur. The lower limit value of the coefficient of dynamic friction is not particularly limited, and it is generally sufficient to set it to about 0.05.

The measurement of the coefficient of dynamic friction in the present invention is performed according to JIS K7125. More specifically, after conditioning the sample of the polyamide-based film at 23° C.×50% RH for 2 hours, the measurement was carried out under the same temperature and humidity conditions. In the case of a laminate containing the film of the present invention as the outermost layer, the surface that will become the outermost layer (usually the protective surface) is used as the measurement surface. The calculation of the dynamic friction coefficient is to take 2 samples from each of the 4 directions specified in the stress characteristic measurement of the above (C-1), measure a total of 8 points, and take the average value as it.

(C-4) Boiling water shrinkage and elastic rate The boiling water shrinkage of the film of the present invention is preferably MD: 2.0-5.0% and TD: 2.5-5.5%, and more preferably MD: 2.0-4.0% and TD: 2.5-4.5 %.

Also, the modulus of elasticity is preferably MD: 1.5-3.0 GPa and TD: 1.5-2.5 GPa, among which MD: 1.8-2.7 GPa and TD: 1.8-2.2 GPa are more preferable.

In order to bond the film of the present invention to the metal foil and to impart sufficient ductility to the metal foil, it is preferable to have the above-mentioned boiling water shrinkage and elastic modulus. That is, when the polyamide-based film has the above-mentioned boiling water shrinkage and elastic modulus, higher flexibility can be imparted to the polyamide-based film, and when it is laminated with metal foil, the metal foil can be more effectively imparted with ductility.

In contrast, when the shrinkage in boiling water is lower than 2.0%, the polyamide-based film is not easily deformed and lacks flexibility, so it is prone to breakage and delamination during cold forming. On the other hand, when the boiling water shrinkage exceeds 5.5%, the flexibility becomes too high, and sufficient ductility cannot be imparted, so that the moldability may be lowered.

When the modulus of elasticity is less than 1.5 GPa, the flexibility becomes too high, and sufficient ductility cannot be imparted, which may lower the formability. In addition, if the modulus of elasticity exceeds 3.0 GPa, there is a possibility that fracture, delamination, etc. may easily occur during cold forming due to lack of flexibility.

The measurement of the shrinkage in boiling water of the present invention is carried out as follows. After conditioning the polyamide-based film at 23°C×50%RH for 2 hours, specify the MD of the film, let it be the MD direction and let the direction at right angles to this direction be TD, and cut into pieces 150mm away from each measurement direction (marked The distance between the lines is 100mm) and the distance between the lines is 15mm in the direction perpendicular to the measurement direction. After measuring the distance between the lines (A), wrap the test piece with gauze and perform hot water treatment at 100°C for 5 minutes. Immediately after treatment, cool with running water and drain, then adjust the humidity at 23°C×50%RH for 2 hours, measure the distance between marking lines (B) and calculate the shrinkage rate according to the following formula. Shrinkage rate=[(A-B)/A]×100

In addition, the measurement of the modulus of elasticity in the present invention is performed as follows. After conditioning the polyamide-based film at 23°C×50%RH for 2 hours, specify the MD of the film, and let the direction perpendicular to MD be TD, and cut the film at a distance of 300mm from each measurement direction (the distance between the marking lines is 250mm) , and a short strip with a distance of 15mm from the direction perpendicular to the measurement direction, using a tensile testing machine (AG-IS manufactured by Shimadzu Corporation) equipped with a load cell for 1kN measurement and a sample chuck, at a test speed of 25mm/min The measurement was carried out under the following conditions, and the modulus of elasticity was calculated from the gradient of the load-extension curve.

(D) Laminate containing the present invention The film of the present invention can be used in various applications in the same manner as known or commercially available polyamide films. In this case, the thin film of the present invention may be used as it is or after surface treatment, or may be used in the form of a laminate in which other layers are laminated.

As a laminate form, a typical example thereof is a laminate comprising the film of the present invention and a metal foil laminated on the film (laminate of the present invention). In this case, the thin film of the present invention may be laminated directly in contact with the metal foil, or may be laminated in a state where other layers are interposed. In particular, the present invention is preferably a laminate obtained by sequentially laminating the film of the present invention/metal foil/sealing film. At this time, it is preferable to make the surface with the protective layer of the film of the present invention the outermost layer (the surface different from the surface to which the metal foil is bonded). Moreover, the layers may also be interposed or not intervened with an adhesive layer as required.

For example, as shown in FIG. 7, a polyamide-based film 50 laminated with a polyamide-based substrate layer 51 and a protective layer 52 has a metal foil 53 and a sealing layer laminated sequentially on the surface on which the protective layer 52 is not formed. 54. Then, a container (battery container) was manufactured by making the sealing layer 54 the side (surface) in contact with the electrolytic solution and making the protective layer 52 the outermost layer. At this time, as mentioned above, an adhesive layer may be interposed between the polyamide base material layer and the metal foil layer as needed. Moreover, you may form an undercoat layer as needed. For example, the primer layer and the adhesive layer may be interposed between the polyamide-based base layer and the metal foil in the form of protective layer/polyamide-based base layer/undercoat layer/adhesive layer/metal foil.

The film of the present invention can be used directly, and can also have a primer layer (anchor coating layer: AC layer) on the entire surface or a part of the surface without a protective layer of the polyamide-based substrate layer as described above. If the adhesive agent is coated on the surface of the film with the primer layer and the metal foil is laminated, the adhesion between the polyamide-based film and the metal foil can be further improved. Thereby, more sufficient ductility can be imparted to metal foil.

Therefore, the polyamide-based film or metal foil is not only difficult to break, but also more effectively prevents delamination or holes from occurring. Those containing the primer layer are also included in the polyamide-based film of the present invention.

Metal foils include metal foils (including alloy foils) containing various metal elements (aluminum, iron, copper, nickel, etc.), but pure aluminum foil or aluminum alloy foil is particularly suitable. The aluminum alloy foil preferably contains iron (aluminum-iron-based alloy, etc.), and other components may contain any components as long as they are within the known content ranges prescribed by JIS or the like within the range that does not impair the formability of the laminate.

The thickness of the metal foil is not particularly limited, but it is preferably 15 to 80 μm, more preferably 20 to 60 μm from the viewpoint of formability and the like.

For the sealing film constituting the laminate of the present invention, heat-sealable thermoplastic resins such as polyethylene, polypropylene, olefin-based copolymers, and polyvinyl chloride are preferably used. The thickness of the sealing film is not limited, and generally it is preferably 20-80 μm, especially 30-60 μm.

In the laminated body of the present invention, an adhesive layer may be interposed between layers. For example, it is desirable to laminate each layer with an adhesive layer such as a urethane-based adhesive layer, an acrylic-based adhesive layer, or the like between polyamide-based film/metal foil, metal foil/sealing film, or the like.

At this time, when the polyamide-based film of the present invention has an undercoat layer on at least one side of the film surface, it is preferable to laminate a metal foil on the undercoat layer surface. Specifically, it is preferable to laminate the metal foil on the surface of the primer layer through an adhesive layer such as a urethane-based adhesive layer or an acrylic adhesive layer.

The laminates of the present invention, especially those containing the film of the present invention, are suitable for cold forming by drawing (especially deep drawing or stretch forming). Here, stretch molding is a method of basically forming a container with a bottom in a shape such as a round tube, an angled tube, or a cone from a laminated body. And described container generally has the characteristic of seamless.

(E) Container containing the laminate of the present invention The present invention also includes a container containing the laminate of the present invention. For example, a container molded using the laminate of the present invention is also included in the present invention. Among them, containers made by cold forming are preferred. It is especially suitable for containers made by stretch forming (drawing processing) or stretch forming (stretching processing) of cold forming, especially containers made by stretch forming.

That is, the container of the present invention can be manufactured suitably by a method for manufacturing a container from the laminate of the present invention, which is characterized by including the step of cold-forming the laminate. Therefore, for example, seamless containers and the like can be produced from the laminate of the present invention.

At this time, the cold forming method itself is not limited, and it can be implemented according to known methods. For example, it is possible to adopt a method of directly molding the resin contained in the laminate in its solid state without melting the resin. As long as the above conditions are satisfied, the molding temperature (temperature of the laminate) can be appropriately set according to the physical properties of the resin used (for example, glass transition point, etc.). Generally speaking, the molding temperature should be set below 50°C, preferably below 45°C. Therefore, for example, cold forming may be performed by setting the forming temperature to normal temperature (about 20 to 30° C.). Furthermore, for example, cold forming may be performed at a temperature below the glass transition point of the resin.

The more specific forming method (processing method) should be such as round pipe drawing processing, square pipe drawing processing, special-shaped drawing processing, conical drawing processing, pyramid drawing processing, ball end drawing processing and other drawing processing. In addition, drawing processing is classified into shallow drawing processing and deep drawing processing, and the laminated body of the present invention is also particularly suitable for deep drawing processing.

Such drawing processing can be carried out using a commonly used mold. For example, a pressing machine equipped with a punch, a die, and a press plate can be applied, and the process including a) disposing the laminate of the present invention between the die and the press plate, and b) pressing the punch into the laminate can be used. In the method of the step of deforming into a container shape, drawing processing is carried out.

The container manufactured in this way can obtain high reliability because it can effectively suppress defects such as metal foil breakage, delamination, and holes. Therefore, the container of the present invention can be used not only as a packaging material for various industrial products but also for various purposes. In particular, the molded body obtained by deep drawing is suitable for the exterior body of lithium-ion batteries, and the molded body obtained by stretch molding is suitable for extrusion packaging and the like.

In particular, the thin film of the present invention is preferably used as an exterior material of a lithium ion battery. When the film of the present invention is used as an exterior material, the protective layer can be used to protect the film of the present invention (especially the polyamide-based substrate layer) from damage by the electrolyte. As a result, problems caused by corrosion of exterior materials and the like can be effectively suppressed or prevented.

Generally speaking, the electrolyte used in lithium-ion secondary batteries is a conductive liquid prepared by dissolving ionic substances (especially lithium salts) in polar solvents such as carbonates. Examples of lithium salts include lithium salts that can generate hydrofluoric acid (hydrogen fluoride) by reacting with water. More specifically, fluorine-containing lithium salts such as lithium hexafluorophosphate (LiPF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ) can be exemplified. Therefore, if the electrolyte is attached to the air, the moisture in the air will react with the fluorine-containing lithium salt in the electrolyte to generate hydrofluoric acid. The hydrofluoric acid will dissolve the polyamide film used for the exterior material of the lithium-ion secondary battery. In contrast, the polyamide-based substrate layer of the film of the present invention is covered by the above-mentioned specific protective layer, so even if the electrolyte solution comes into contact with the exterior material, it can still effectively protect the exterior material with high electrolyte resistance, and as a result, it can provide Li-ion secondary battery with high reliability.

2. Production method of the film of the present invention The polyamide-based film of the present invention can be produced by the production method shown below, which satisfies the characteristic values in the preceding paragraph. More specifically, it is a method for producing a polyamide-based film, which is a method for producing a film comprising a polyamide-based substrate layer and a protective layer formed on at least one side of the substrate layer. The characteristics of the production method It comprises the following steps: (1) forming the melt-kneaded product containing polyamide resin into a sheet shape to obtain an unstretched sheet (forming step); (2) forming the aforementioned unstretched sheet successively or Simultaneously carry out biaxial stretching to MD and TD to obtain a stretched film step (stretching step); wherein, (3) satisfy both the following formulas a) and b): a) 0.85≦X/Y≦0.95 b) 8.5 ≦X×Y≦9.5 (only, X represents the elongation ratio of the aforementioned MD, Y represents the elongation ratio of the aforementioned TD); At least one side of a film extending in at least one direction of MD and TD is coated with a vinyl alcohol-based polymer (A) containing a vinyl alcohol unit and a vinyl polymer (B) containing an unsaturated carboxylic acid unit liquid step (coating step).

Sheet forming step In the sheet forming step, the melt-kneaded product containing polyamide resin is formed into a sheet to obtain an unstretched sheet.

As the polyamide resin, various materials described above can be used. In addition, various additives may be contained in the melt-kneaded product. The preparation itself of the melt-kneaded product may be carried out according to a known method. For example, the raw material containing polyamide resin can be fed into an extruder equipped with a heating device, heated to a predetermined temperature to melt, extrude the melted kneaded product with a T-die, and cool and solidify with a casting roller, etc. Thus, an unstretched sheet of a sheet-shaped molded body is obtained.

The average thickness of the unstretched sheet at this time is not particularly limited, but is generally about 15 to 250 μm, particularly preferably 50 to 235 μm. By setting within the range, the elongation step can be performed more efficiently.

Stretching step In the stretching step, the aforementioned unstretched sheet is biaxially stretched in MD and TD successively or simultaneously to obtain a stretched film.

As mentioned above, it is preferably obtained by successive biaxial stretching including a step of stretching in at least one direction of MD and TD using a tenter. Thereby, a more uniform film thickness can be produced.

The tenter itself is a device used to stretch a film from the past. It is a device that holds both ends of an unstretched sheet and stretches it in the longitudinal direction and/or transverse direction. There are two methods of simultaneous biaxial stretching and sequential biaxial stretching using a stenter. Simultaneous biaxial stretching using a stenter is a method of holding both ends of the unstretched film to stretch toward MD and stretching toward TD at the same time, and using a tenter to simultaneously perform biaxial stretching of MD and TD.

However, using a tenter for successive biaxial stretching, there are: 1) After the unstretched sheet is stretched in MD by a plurality of rollers with different rotation speeds, the stretched film is stretched to TD with a tenter ; and 2) After stretching the unstretched sheet to MD with a tenter, the stretched film is stretched to TD with a tenter, etc., but it is especially suitable from the viewpoint of the physical properties and productivity of the obtained film It is the method of the aforementioned 1). The method of the aforementioned 1) performs the steps shown in FIG. 2 to carry out successive biaxial stretching of the unstretched film.

First, as shown in FIG. 2 , the unstretched sheet 13 is stretched in the MD (machine direction) by passing through a plurality of rollers 21 . Since the rotational speeds of the plurality of rollers are different from each other, the unstretched sheet 13 is stretched in the MD by utilizing the speed difference. That is, the unstretched sheet is stretched from a group of low-speed rollers through a group of high-speed rollers.

In addition, although the number of rolls is 5 in FIG. 2, it may be other numbers actually. In addition, rolls having different functions may be provided in the form of, for example, a preheating roll, a stretching roll, and a cooling roll in this order. The number of rollers having each of these functions can also be appropriately set. Also, when a plurality of stretching rollers are provided, stretching may be performed in multiple stages. For example, by setting the first stage as the stretching ratio E1 and the second stage as the stretching ratio E2 to carry out two-stage stretching, the MD stretching ratio can be appropriately set within the range of (E1×E2). The first stretched film 13' was produced as described above.

Next, the first stretched film 13' having passed through the roll 21 is introduced into a tenter 22 and stretched in TD. Specifically, as shown in FIG. 3 , both ends of the first stretched film 13 ′ that have been introduced into the tenter 22 are gripped by clips connected to the link device 34 fixed on the guide rail near the entrance, and are held according to the The sequence of the flow direction passes through the preheating zone 31 , the extension zone 32 and the relaxation heat treatment zone 33 . After the first stretched film 13' is heated to a fixed temperature in the preheating zone 31, it is stretched toward TD in the stretching zone 32. Then, in the relaxation heat treatment zone 33, relaxation treatment is performed at a fixed temperature. As described above, the second stretched film 14 (film of the present invention) was produced. After that, the link device 34 fixed on the guide rail is removed from the second stretched film 14 near the exit of the tenter 22 and put back near the entrance of the tenter 22 .

According to the above, using a tenter to carry out successive biaxial stretching, it is beneficial to productivity and equipment to use a roll to stretch to MD, and to use a tenter to stretch to TD is beneficial to control the film thickness.

In the production method of the polyamide-based film of the present invention, the stretching step preferably satisfies both the following formulas a) and b): a) 0.85≦X/Y≦0.95 (preferably 0.89≦X/Y≦0.93) b) 8.5 ?

When any one of the above-mentioned conditions a) and b) is not satisfied, the stress balance in the four directions of the obtained polyamide-based film will become poor and it will be difficult to obtain the film of the present invention.

The temperature condition of the elongation step, for example, is suitable for elongation at a temperature range of 180° C. to 220° C. during the aforementioned simultaneous biaxial stretching. And for example, when carrying out the aforementioned successive biaxial stretching, it is preferable to perform MD stretching at a temperature range of 50~120°C (especially 50~80°C, and 50~70°C, and 50~65°C), and preferably at 70°C TD stretching is carried out at a temperature range of ~150°C (especially 70~130°C, and 70~120°C, and 70~110°C). By controlling the temperature within the above range, the thin film of the present invention can be produced more reliably. These temperatures can be preheated, set and controlled by, for example, the roll 21 (roll for preheating) shown in FIG. 2 and the preheating zone 31 of the tenter shown in FIG. 3 .

In addition, it is preferable to perform relaxation heat treatment after stretching simultaneously with simultaneous biaxial stretching and sequential biaxial stretching using a tenter. Relaxation heat treatment should be set at a temperature range of 180~230°C with a relaxation rate of 2~5%. These temperatures can be set and controlled in the relaxation heat treatment zone of the tenter shown in Figure 3. The means for setting the temperature range during stretching to the above-mentioned means include a method of blowing hot air on the surface of the film, or a method of using a far-infrared or near-infrared heater, and a combination of these methods, etc., and the heating method of the present invention is preferably Contains the method of blowing hot air.

<Embodiment of Stretching Step> As the stretching step in the present invention, a sequential biaxial stretching step of stretching to MD with a roll and stretching to TD with a tenter can be suitably employed. By adopting this method and satisfying the temperature conditions shown below, since the stress balance in the above-mentioned four directions during elongation can be made more excellent, and the thickness accuracy in the above-mentioned four directions can be made high, it can be more reliably and efficiently produced in particular. The film of the present invention having an average thickness of 15 μm or less.

MD Stretching Firstly, the temperature of MD stretching should be stretched with rollers in the temperature range of 50~70°C, among which the temperature should be set at 50~65°C.

MD extension should be multi-stage extension with more than 2 stages. At this time, it is appropriate to increase the elongation ratio step by step. That is, it is controlled so that the elongation ratio of the (n+1)th stage is higher than the elongation bridge ratio of the nth stage. In this way, the whole can be extended more uniformly. For example, when stretching in two stages, the stretching ratio in the first stage can be set to 1.1~1.2, and the stretching ratio in the second stage can be set to 2.3~2.6 for two-stage stretching, and the stretching ratio in the longitudinal direction can be set at 2.53~ Appropriate setting within the scope of 3.12.

Also, it is preferable to set a temperature gradient for MD extension. In particular, the temperature is increased sequentially along the pulling direction of the film. For the MD extension as a whole, the temperature gradient (the temperature difference between the temperature T1 at the starting point (entrance) and the temperature T2 at the end point (exit) of the film moving direction) is general. It is preferably above 2°C, more preferably above 3°C. At this time, the film moving time (heating time) between the starting point (entrance) and the end point (exit) of the film moving direction is generally preferably 1 to 5 seconds, particularly preferably 2 to 4 seconds.

TD Stretching TD stretching was stretched using a tenter frame formed with zones as shown in FIG. 3 . At this time, the temperature in the preheating zone should be set at 60~70°C. Then, it is preferable to set the temperature of the extension zone at a temperature range of 70-130°C, especially at a temperature range of 75-120°C, and most preferably at a temperature range of 80-110°C.

In addition, it is also appropriate to increase the temperature sequentially along the pulling direction of the film in the stretching region. Especially in the extension area as a whole, the temperature gradient (the temperature difference between the temperature T1 of the starting point (entrance) and the temperature T2 of the end point (exit) of the film moving direction) should generally be set above 5°C, and more preferably set above 8°C. good. At this time, the film moving time (heating time) between the starting point (entrance) and the end point (exit) of the film moving direction in the extension zone is preferably 1 to 5 seconds, especially 2 to 4 seconds.

It is advisable to perform a relaxation heat treatment on the stretched film. The relaxation heat treatment is carried out in the relaxation heat treatment zone, and the heat treatment temperature is preferably set in the range of 180~230°C, more preferably in the range of 180~220°C, and the best is 180~210°C. Also, the relaxation rate should generally be set at about 2 to 5%.

Coating step In the coating step, a vinyl alcohol-based polymer containing vinyl alcohol units (A ) and a coating solution of a vinyl polymer (B) containing an unsaturated carboxylic acid unit.

As long as the coating liquid contains A component and B component, for example, a mixed solution in which A component and B component are dissolved in a solvent, a dispersion liquid in which A component and B component are dispersed in a solvent, etc., it is particularly suitable to use mixture.

As the solvent used in the coating solution, in addition to water, at least one solvent such as lower alcohol (especially methanol, ethanol, propanol, isopropanol, etc.), methyl ethyl ketone, methyl acetate, benzene, and toluene can be used. In particular, when component A and component B are water-soluble, it is particularly preferable to use water as a solvent from the viewpoint of process environment and solvent cost. On the other hand, in order to improve solubility, shorten drying steps, improve solution stability, etc., it is more effective to use a mixed solvent of water and a water-soluble organic solvent (for example, adding a small amount of water-soluble organic solvent such as alcohol to water). In addition, in order to improve the electrolyte resistance of the film of the present invention, the crosslinking reaction between component A and component B must be carried out by means of ester bonds, and a catalyst such as acid can also be added in order to promote the crosslinking reaction.

Moreover, when preparing a coating liquid, it is preferable to add 0.1-20 equivalent % of alkali compounds with respect to the carboxyl group of the unsaturated carboxylic acid of B component. In particular, monovalent alkali metal compounds are preferred, and alkali compounds containing sodium or potassium are most preferred. The hydrophilicity of unsaturated carboxylic acid will increase if the carboxyl group content is high, so it can be made into an aqueous solution even without adding an alkali compound, but by adding an appropriate amount of alkali compound, the electrolyte resistance of the prepared laminate can be further improved sex. The alkali compound should just be what can neutralize the carboxyl group of an unsaturated carboxylic acid, For example, sodium hydroxide etc. can be used suitably. Also, the amount of the base compound added is preferably 0.1 to 20 mol% with respect to the carboxyl group of the unsaturated carboxylic acid.

Preparation of a coating liquid can be performed by a well-known method using the melting tank etc. equipped with a stirrer. For example, a method of preparing component A and component B into aqueous solutions and mixing them before coating may be suitably employed. At this time, the stability of the aqueous solution can be further improved by first adding the above-mentioned alkali compound to the aqueous solution of component B.

The concentration (solid content concentration) of the coating liquid can be changed as appropriate according to the viscosity or reactivity of the coating liquid, the specifications of the equipment used, etc., and can be set within the range of 5 to 70% by mass. If the concentration of the coating solution is too low, it will be difficult to obtain a layer with a desired thickness, and the subsequent drying step will take a long time. On the other hand, if the concentration of the coating liquid is too high, problems will arise in terms of mixing operation, storage stability, and the like.

The coating method of the coating liquid is not particularly limited, and general methods such as gravure roll coating, reverse roll coating, and wire bar coating can be used, for example.

Coating may be performed on at least one side of a) an unstretched sheet or b) a film stretched in at least one direction of MD and TD. That is, it may be any case of coating an unstretched sheet, coating a film stretched in one direction of MD and TD, or coating a film stretched in both directions of MD and TD. Therefore, the coating step can also be performed on the stretched film produced through the above-mentioned stretching step and relaxation heat treatment step, or can be performed on the film before stretching or between the stretching steps.

In addition, in the present invention, the protective layer composed of polymer (A) and polymer (B) formed on at least one side of the film is preferably subjected to heat treatment after coating in order to cause cross-linking reaction of the two polymers. At this time, the temperature of the heat treatment is not limited, but it is generally suitable to be carried out in a gas environment of 180-230°C. If the heat treatment temperature is too low, the crosslinking reaction cannot be fully carried out, and it is difficult to prepare a film with sufficient electrolyte resistance. On the other hand, if the heat treatment temperature is too high, there is a possibility of embrittlement of the protective layer.

In addition, the heat treatment time is generally preferably less than 5 minutes, more preferably 1 second to 5 minutes, and more preferably 3 seconds to 2 minutes. If the heat treatment time is too short, the above-mentioned cross-linking reaction cannot be sufficiently carried out, and it is difficult to obtain an electrolyte-resistant protective layer. On the other hand, if the heat treatment time is too long, productivity will be reduced.

Therefore, in the present invention, it is preferable to perform the coating step before the step of subjecting the stretched film to the relaxation heat treatment. Among them, after MD stretching, a method (continuous coating) in which a coating solution is applied to a film stretched in MD and then stretched in TD is preferably used. In addition, the same stretching and heat treatment conditions as above can also be used when stretching and heat treating a film coated before stretching or during stretching.

In addition, in the production method of the present invention, in the stretching step, it is preferable not to use stretching methods other than those described above from the viewpoint of maintaining thickness uniformity and the like. For example, the stretching step by blown film stretch molding (inflation) is excluded.

EXAMPLES Examples and comparative examples are shown below to further specifically describe the characteristics of the present invention. However, the scope of the present invention is not limited to the examples. Measurement and evaluation of various characteristic values in the present invention are performed as follows.

(1) Stress in 4 directions of polyamide film at 5% elongation and 15% elongation Stress in 4 directions of polyamide film at 5% elongation and 15% elongation Let MD be the reference direction ( 0 degree direction), and calculated according to the method described above. In addition, the sample film used for the measurement was taken near the center of the roll width and half of the roll volume of the produced polyamide-based film wound up on the film roll.

(2) Average thickness and standard deviation of the polyamide-based film The average thickness and standard deviation of the polyamide-based film were measured and calculated according to the aforementioned methods. In addition, the sample films used for the measurement are the following three types. Among the obtained polyamide-based films wound on film rolls, a) the position taken near the center of the roll width and half of the roll volume is represented as "A", and b) the position near the right end of the roll width and located The position taken at half of the volume is marked as "B", and the position taken at c) near the left end of the width of the roll and near the end of the curl is marked as "C".

(3) Boiling water shrinkage and elastic modulus of polyamide-based film The boiling water shrinkage and elastic modulus of the polyamide-based film were measured by the methods described above. In addition, the sample film used for the measurement was taken near the center of the roll width and half of the roll volume of the produced polyamide-based film wound up on the film roll.

(4) Dynamic friction coefficient of polyamide-based film The dynamic friction coefficient of the polyamide-based film was measured by the method described above. In addition, the sample film used for the measurement was taken from the position near the center of the roll width and half the volume of the produced polyamide-based film wound up on the film roll. In addition, only Examples 1, 6, 7, 13, and 42 to 53 were measured. All measurements were performed on the surface of the coating layer of the polyamide-based film.

(5) Thickness of protective layer The prepared polyamide-based film was embedded in epoxy resin, and slices with a thickness of 100 nm were taken with a cryo-ultramicrotome. The cutting temperature was set at -120° C., and the cutting speed was set at 0.4 mm/min. The taken sections were gas-phase stained with RuO ₄ solution for 1 hour, and the thickness of the protective layer was measured by transmission measurement at an accelerating voltage of 100 kV using a JEM-1230 TEM (manufactured by JEOL Ltd.). At this time, the thickness of the protective layer was measured at any 5 points, and the average value of the measured values at 5 points was taken as the thickness. In addition, the sample film used for the measurement was taken from the position near the center of the roll width and half the volume of the produced polyamide-based film wound up on the film roll.

(6) Molding of the laminate [extension depth (Erichsen test)] According to JISZ2247, using the Erichsen test machine (No.5755 manufactured by Yasuda Seiki Co., Ltd.), the obtained laminate was The Erikson value is obtained by pressing the punch with the steel ball at the predetermined pressing depth. The Ericsson value is measured every 0.5mm. We judge that the Ericsson value is better than 5mm, especially 8mm or more is suitable for deep drawing.

(7) Electrolyte solution resistance performance Using the prepared polyamide-based film, the electrolytic solution resistance performance was evaluated for three kinds of storage times shown below: 6 hours, 12 hours, and 24 hours. Specifically, the opening of a glass dish (200 mm in diameter) was covered with a polyamide-based film and the protective layer was used as the surface, and 10 ml of electrolyte solution (made of ethylene carbonate/diethylene carbonate) was dropped on the protective layer. ester/ethyl methyl carbonate = 1/1/1 (volume ratio) mixed with LiPF ₆ solution, the concentration is 1 mole/L), so that the protective layer is attached to the electrolyte, and at room temperature (23 ℃) and place them for the above-mentioned times respectively. After that, the electrolyte on the protective layer was wiped off with gauze and the appearance was visually observed. Also, the stress in the MD direction at 15% elongation (stress 2) was measured in the same manner as (1) for the polyamide-based film after being left to stand for each time and visually observing its appearance. The stress retention rate was calculated according to the following formula using the value of the stress (stress 1) in the MD direction when the polyamide-based film was stretched by 15% before dropping the electrolytic solution. Stress retention rate (%)=(stress 2/stress 1)×100 Then, the total evaluation of electrolyte resistance performance is carried out according to the following 3 stages. ○: There is no change in appearance, and the stress retention rate is more than 95%. △: There is no change in appearance, but the stress retention rate is less than 95% and more than 90%. X: Changes in appearance (whitening) are observed, and stress retention is observed. When the rate is less than 90%

Preparation Example 1 First, a mixed solution (coating solution) for forming a protective layer was prepared. Polyvinyl alcohol (PVA) (manufactured by Kuraray Co., Ltd., POVAL 105 (saponification degree 98-99 mol%, average degree of polymerization about 500)) was dissolved in hot water and cooled to room temperature to obtain a solid content of 15 mass % PVA aqueous solution. Also, dissolve EMA (weight average molecular weight 60,000, maleic acid unit 45-50%) and sodium hydroxide in hot water and cool to room temperature to prepare a solid with 10 mol% of carboxyl groups neutralized by sodium hydroxide The component is a 15% by mass EMA aqueous solution. Next, the two aqueous solutions were mixed so that the molar ratio of the vinyl alcohol unit in PVA and the maleic acid unit in EMA was 30:70, and stirred at room temperature to prepare a coating solution 1 .

Preparation Example 2 Coating solution 2 was prepared in the same manner as coating solution 1 except that the two aqueous solutions were mixed so that the molar ratio of vinyl alcohol units in PVA and maleic acid units in EMA was 10:90.

Preparation Example 3 Coating solution 3 was prepared in the same manner as coating solution 1, except that the two aqueous solutions were mixed so that the molar ratio of vinyl alcohol units in PVA and maleic acid units in EMA was 50:50.

Preparation Example 4 In addition to dissolving EXCEVAL RS2117 (saponification degree 97.5 to 99 mole%) manufactured by Kuraray Co., Ltd. in hot water and cooling to room temperature to prepare an aqueous solution of EXCEVAL (EVOH) with a solid content of 10% by mass instead of the aqueous PVA solution, Coating solution 4 was prepared by mixing the two aqueous solutions in the same manner as coating solution 1 so that the molar ratio of vinyl alcohol units and EMA maleic acid units was 30:70.

Preparation Example 5 Dissolve methyl vinyl ether/maleic anhydride copolymer ("GANTREZ AN119" manufactured by Ashland Specialty Ingredients Co., Ltd.) and sodium hydroxide in hot water and cool to room temperature to obtain a carboxyl group with 10 mole % Sodium hydroxide neutralized an aqueous solution having a solid content of 10% by mass instead of EMA. Next, the two aqueous solutions were mixed in the same manner as in coating solution 1 so that the molar ratio of vinyl alcohol units in PVA and maleic acid units in GANTREZ was 30:70, and stirred at room temperature to prepare coating solution 5.

Preparation Example 6 Coating solution 6 was prepared by adding silicon oxide as an inorganic lubricant to the coating solution prepared in the same manner as coating solution 1 so that the content of silicon oxide in the protective layer was 0.6% by mass.

Preparation Example 7 Coating solution 7 was prepared by adding silicon oxide as an inorganic lubricant to the coating solution prepared in the same manner as coating solution 1 so that the content of silicon oxide in the protective layer was 1.8% by mass.

Preparation Example 8 Coating solution 8 was prepared by adding silicon oxide as an inorganic lubricant to the coating solution prepared in the same manner as coating solution 1 so that the content of silicon oxide in the protective layer was 6.0% by mass.

Example 1 (1) Production of polyamide-based film Use polyamide 6 resin (A1030BRF, relative viscosity 3.1) manufactured by UNITIKA Company and nylon 6 resin (A1030QW, relative viscosity 2.7) containing 6% by mass of silicon oxide as The raw materials are melted and kneaded in an extruder at a composition ratio of A1030BRF/polyamide nylon resin containing silicon oxide=98.7/1.3 (mass ratio), and supplied to a T-die to form a sheet. The aforementioned sheet was wound onto a metal roll whose temperature had been adjusted to 20°C, allowed to cool, and wound up to produce an unstretched sheet. At this time, the supply amount of the polyamide resin and the like were adjusted so that the thickness of the polyamide-based film obtained after stretching could be 15 μm. Next, the resulting unstretched sheet is subjected to a stretching step using sequential biaxial stretching. More specifically, stretching is performed by a method in which stretching is performed using a tenter in TD after stretching the sheet in MD with rolls. First, in MD stretching, the aforementioned sheet is stretched by passing a plurality of stretching rolls, and the total stretching ratio in MD is conventionally 2.85 times. At this time, stretching is performed in two stages, and the stretching ratio of the first stage is 1.1, and the stretching ratio of the second stage is 2.59. The total stretching ratio (MD1×MD2) is 1.1×2.59=2.85 times. The heating conditions were stretched by setting a temperature gradient along the film pulling direction such that the starting point (T1) of the moving direction was 58°C and the ending point (T2) was 61°C. At this time, the film traveling time (heating time) between the starting point (entrance) and the end point (exit) of the film traveling direction is about 3 seconds. After the MD stretching, the coating solution 1 was applied to one side of the film using a gravure coater so that the thickness of the coating resist after stretching became 0.3 μm. Afterwards, TD extension is performed. TD stretching was carried out using a tenter frame as shown in FIG. 3 . Firstly, the temperature in the preheating zone (preheating part) is set to 70°C for preheating, and it is extended 3.2 times in the extension zone to TD. At this time, in the stretching region (stretching portion), a temperature gradient was set along the film pulling direction such that the starting point (T1) of the moving direction was 78°C and the ending point (T2) was 100°C. At this time, the film moving time (heating time) between the starting point (entrance) and the end point (exit) of the film moving direction in the stretching zone is about 3 seconds. The film passing through the stretching zone was subjected to a relaxation heat treatment at a temperature of 202° C. for 3 seconds and a relaxation rate of 3% in a relaxation heat treatment zone (heat treatment section). After continuous production of more than 1000 m as above, a biaxially stretched polyamide film (roll volume: 2000 m) having a protective layer with a thickness of 0.3 μm formed on one side of the polyamide base layer was obtained. And the obtained film is taken up into a roll shape.

(2) Manufacture of a laminate. Coat the biaxially stretched polyamide film (the surface without the protective layer) obtained in the above (1) with a coating amount of 5 g/ ^m2 to coat the two-component polyurethane system. Adhesive (Toyo Morton Co., Ltd. "TM-K55/CAT-10L)") was dried at 80°C for 10 seconds. And a metal foil (50-micrometer-thick aluminum foil) was bonded to this adhesive-coated surface. Next, after coating the above-mentioned adhesive on the aluminum foil side of the laminate of the polyamide-based film and the aluminum foil under the same conditions as above, a sealing film (unstretched polypropylene film (manufactured by Mitsui Chemicals Tohcello.Inc. GHC (thickness: 50 μm)), and hardening treatment for 72 hours in a 40°C gas environment to produce a laminate (polyamide-based film/aluminum foil/sealing film).

2-22, Comparative Examples 1-14 Except that the production conditions and the target thickness of the stretched polyamide-based film were changed to those shown in Tables 1-2 and Table 5, polyamide-based films were prepared in the same manner as in Example 1. Amine film. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film. In addition, the unit of the average thickness, thickness precision, and the thickness of the protective layer in each of these tables is "μm".

Examples 23-28 Except changing the thickness of the protective layer as shown in Table 7, polyamide-based films were produced in the same manner as in Example 1. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film. In addition, in Table 7, the units of the average thickness, the thickness precision, and the thickness of the protective layer are "μm".

Example 29 A polyamide-based film was produced in the same manner as in Example 5 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film. In addition, in Table 8, the unit of the average thickness, the thickness precision, and the thickness of the protective layer is "μm".

Example 30 A polyamide-based film was prepared in the same manner as in Example 7 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 31 A polyamide-based film was produced in the same manner as in Example 12 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 32 A polyamide-based film was prepared in the same manner as in Example 11 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 33 A polyamide-based film was produced in the same manner as in Example 13 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 34 A polyamide-based film was produced in the same manner as in Example 15, except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 35 A polyamide-based film was produced in the same manner as in Example 6 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 36 A polyamide-based film was prepared in the same manner as in Example 22 except that the thickness of the protective layer was changed to that shown in Table 8. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Examples 37-40 After MD stretching, except that any one of the coating solutions 2-5 shown in Table 8 was used instead of the coating solution 1, polyamide-based films were prepared in the same manner as in Example 1. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Example 41 The raw materials used are polyamide 6 resin (A1030BRF) manufactured by UNITIKA, polyamide 66 resin (A226) manufactured by UNITIKA, and nylon 6 resin (A1030QW) containing 6% by mass of silicon oxide. The composition ratio is A1030BRF/ The composition of A226/A1030QW=89.0/9.7/1.3 (mass ratio), and the production conditions were changed to those shown in Table 1, and the polyamide-based film was prepared in the same manner as in Example 30. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Examples 42, 46, and 50 After MD stretching, polyamide-based films were prepared in the same manner as in Example 1, except that any of coating solutions 6-8 shown in Table 9 was used instead of coating solution 1. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film. In addition, in Table 9, the unit of the average thickness, the thickness precision, and the thickness of the protective layer is "μm".

Examples 43, 47, 51 After MD stretching, polyamide-based films were prepared in the same manner as in Example 7, except that any one of coating solutions 6-8 shown in Table 9 was used instead of coating solution 1. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Examples 44, 48, and 52 After MD stretching, polyamide-based films were prepared in the same manner as in Example 13, except that any of coating solutions 6-8 shown in Table 9 was used instead of coating solution 1. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Examples 45, 49, and 53 After MD stretching, polyamide-based films were prepared in the same manner as in Example 21, except that any of coating solutions 6-8 shown in Table 9 was used instead of coating solution 1. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Comparative Example 15 A polyamide-based film was produced in the same manner as in Example 7 except that the condition of not applying the coating liquid 1 was changed. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Comparative Example 16 A polyamide-based film was produced in the same manner as in Example 8, except that the condition of not applying the coating liquid 1 was changed. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Comparative Example 17 was changed to use 7 parts by mass of tri( methoxymethyl) melamine resin ("BECKAMINE APM" manufactured by DIC Corporation, Tts=150°C) was used instead of the coating liquid 1, and polyamide was prepared in the same manner as in Example 1. Department of film. A laminate was produced in the same manner as in Example 1 using the obtained polyamide-based film.

Test Example 1 The physical properties of the polyamide-based films and laminates produced in each of the examples and comparative examples were evaluated. The evaluation results are shown in Tables 6-15. In addition, in Tables 1 to 15, the unit of temperature is "°C", the unit of average thickness and thickness accuracy is "μm", the unit of protective layer thickness is "μm", and the unit of stress is "MPa". The unit of boiling water shrinkage is expressed as "%", the unit of elastic modulus is expressed as "GPa", and the unit of drawing depth is expressed as "mm".

[Table 1]

[Table 2]

[table 3]

[Table 4]

[table 5]

[Table 6]

[Table 7]

[Table 8]

[Table 9]

[Table 10]

[Table 11]

[Table 12]

[Table 13]

[Table 14]

[Table 15]

From these results, it is obvious that the elongation ratios of the polyamide-based films in Examples 1-53 are in the predetermined range, so the prepared polyamide-based films are satisfied in the uniaxial tensile test toward the 0 degree direction, 45 The difference between the maximum value and the minimum value of the stress at 5% elongation in the direction of 10°, 90° and 135° is 35MPa or less, and the difference between the maximum and minimum value of the stress at 15% elongation is 40MPa or less. Furthermore, the laminates produced using these polyamide-based films have a high Ericsson value and have ductility that can be uniformly extended in all directions during cold forming. That is, it can be seen that the polyamide-based films of these examples have excellent formability without aluminum foil breakage, delamination, or voids.

In addition, the polyamide-based films obtained in Examples 1 to 53 have a vinyl-alcohol-based polymer (A) containing vinyl-alcohol units and a vinyl-based polymer (B) containing unsaturated carboxylic acid units on one side. Therefore, the laminate using these polyamide-based films also has excellent electrolyte resistance.

In addition, the polyamide-based films prepared in Examples 42 to 53 contain inorganic lubricants in the protective layer, so the coefficient of dynamic friction is low, and the laminates using these polyamide-based films have excellent smoothness, In particular, it has particularly excellent cold formability.

In contrast, comparative examples 1 to 14, in particular, the elongation ratio of the polyamide-based films did not meet the predetermined range, so the prepared polyamide-based films were not satisfied in the direction of 0 degrees and 45 degrees in the uniaxial tensile test. The difference between the maximum value and the minimum value of the stress when 5% elongation is caused by the direction, 90 degree direction and 135 degree direction is less than 35MPa, and the difference between the maximum value and the minimum value of the stress when 15% elongation is not satisfied is less than 40MPa. Therefore, the laminates produced using the polyamide-based films of these comparative examples have low Ericsson values, do not have ductility to uniformly extend in all directions during cold forming, and are poor in formability.

In addition, Comparative Examples 15 to 17 did not have a protective layer containing a vinyl alcohol-based polymer (A) containing a vinyl alcohol unit and a vinyl-based polymer (B) containing an unsaturated carboxylic acid unit, so the electrolyte resistance was poor. On the other hand, pores are generated in the polyamide-based film due to the electrolyte.

11‧‧‧raw material 11a‧‧‧melt kneading step 12‧‧‧melt kneading product 12a‧‧‧shaping step 13‧‧‧unstretched sheet 13'‧‧‧the first stretched film 13a‧‧‧stretching step 14‧ ‧‧Second Stretched Film; Polyamide-based Film (Film of the Present Invention) 14a ‧‧‧Product 21‧‧‧Roll 22‧‧‧Tenter 31‧‧‧Preheating Zone 32‧‧‧Extension Zone 33‧‧‧Relaxing Heat Treatment Zone 34‧‧‧Connecting Rod Device 41‧‧‧Sample 50 ‧‧‧Polyamide-based film 51‧‧‧Polyamide-based substrate layer 52‧‧‧protective layer 53‧‧‧metal foil 54‧‧‧sealing layer A‧‧‧central point a‧‧‧direction

Fig. 1 is a schematic diagram showing the outline of the manufacturing steps and cold working steps of the polyamide-based film of the present invention. Fig. 2 is a schematic diagram showing the step of stretching the unstretched sheet by successive biaxial stretching in the manufacturing method of the present invention. Fig. 3 is a diagram showing a state in which a stretching step is performed by a tenter viewed from the direction a in Fig. 2 . Figure 4 shows the direction in which the stress of the thin film was measured. The one shown in Fig. 5 is a sample used to measure the stress of the thin film. Figure 6 shows a method for measuring the average thickness of a film. Fig. 7 shows the layer structure of an embodiment of the laminate of the present invention.

50‧‧‧polyamide film

51‧‧‧Polyamide base layer

52‧‧‧protective layer

53‧‧‧Metal foil

54‧‧‧Sealing layer

Claims (10)

A polyamide-based film, characterized in that it contains a polyamide-based substrate layer and a protective layer formed on at least one side of the substrate layer, and (1) the aforementioned protective layer contains a vinyl alcohol-based polymer containing vinyl alcohol units ( A) and a vinyl polymer (B) containing an unsaturated carboxylic acid unit (but does not include the aforementioned vinyl alcohol polymer (A)); (2) the aforementioned film is as follows: (2-1) the aforementioned film is After 2 hours of humidity control at 23°C×50%RH, starting from any point in the above-mentioned film, take a specific direction as 0°, clockwise 45°, 90° and 135° relative to this direction, and perform uniaxial stretching. The difference between the maximum value and the minimum value of each stress when the tensile test causes 5% elongation is 35 MPa or less; and (2-2) in the aforementioned 4 directions, the maximum value and the value of each stress when the uniaxial tensile test is carried out to cause 15% elongation The difference between the minimum values is 40 MPa or less. The polyamide-based film according to claim 1, wherein the unsaturated carboxylic acid unit contains at least one maleic acid-based unit among maleic acid and maleic anhydride units. Such as the polyamide film of claim 1, wherein the aforementioned protective layer is as follows: (3-1) the vinyl alcohol unit content in the vinyl alcohol polymer (A) is more than 40 mole %; and (3-2) ethylene The unsaturated carboxylic acid unit content in the base polymer (B) is 10 mol% or more. The polyamide film according to claim 1, wherein the molar ratio of vinyl alcohol units to unsaturated carboxylic acid units (vinyl alcohol units/unsaturated carboxylic acid units) in the protective layer is 1/99~60/40. The polyamide-based film according to claim 1 or 2, wherein counting from any point in the aforementioned film, the specific direction is 0 degrees, 45 degrees clockwise relative to the direction, 90 degrees, 135 degrees, 180 degrees, 225 degrees, The standard deviation of the thickness in 8 directions of 270 degrees and 315 degrees is 0.200 μm or less. The polyamide-based film according to Claim 1, which has an average thickness of 16 μm or less. The polyamide film according to claim 1, wherein at least one surface has a dynamic friction coefficient of 0.60 or less. A laminate comprising the polyamide film according to any one of claims 1 to 7 and a metal foil laminated on the film. A container containing the laminate according to Claim 8. A method for producing a polyamide-based film, characterized in that it is a method for producing the following film: comprising a polyamide-based substrate layer and a protective layer formed on at least one side of the substrate layer, (a) heating the aforementioned film at 23°C ×50%RH After conditioning for 2 hours, starting from any point in the above-mentioned film, the specific direction is 0 degrees, and relative to the direction clockwise 45 degrees, 90 degrees and 135 degrees, a total of 4 directions, the uniaxial tensile test is carried out The difference between the maximum value and minimum value of each stress when 5% elongation is caused is 35MPa or less; and (b) the difference between the maximum value and minimum value of each stress when 15% elongation is caused by uniaxial tensile test in the aforementioned 4 directions Below 40MPa; The manufacturing method comprises the following steps: (1) forming a sheet of an unstretched sheet by forming a melt-kneaded product containing polyamide resin into a sheet; (2) feeding the aforementioned unstretched sheet to the MD and TD are biaxially stretched to obtain a stretched film; and (3) both of the following formulas a) and b) are satisfied: a) 0.85≦X/Y≦0.95 b) 8.5≦X×Y≦9.5( However, X represents the elongation ratio of the aforementioned MD, and Y represents the elongation ratio of the aforementioned TD); the following steps are also included: (4) between a) an unstretched sheet or b) a film stretched in at least one direction towards MD and TD On at least one side, the step of coating a coating liquid containing a vinyl alcohol-based polymer (A) containing vinyl alcohol units and a vinyl-based polymer (B) containing unsaturated carboxylic acid units; (5) during MD stretching The temperature is 50~74℃, and the temperature during TD stretching is 70~150℃.

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