WO2020203836A1 - Polyamide-based laminated film and method for producing same - Google Patents

Abstract

[Problem] To provide a polyamide-based laminated film endowed with both high slipperiness and good printability. [Solution] The present invention pertains to a laminated film including a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant on at least one surface of the polyamide film, wherein the polyamide-based laminated film is characterized in that (1) the glass transition temperature of the polyurethane resin is 50°C or higher, (2) the arithmetic mean height (Ra) of the polyurethane resin layer surface is 0.010 to 0.060 μm, and the dynamic friction coefficient of the polyurethane resin layer surface in a 20°C×90% RH environment is 0.40 or lower.

Description

Polyamide-based laminated film and its manufacturing method

The present invention relates to a polyamide-based laminated film used for packaging or coating foods, electronic parts, etc.

Polyamide film has excellent toughness, so it is widely used from food packaging to industrial applications. Resin films such as polyamide films are processed by a printing machine, laminator, etc., depending on the intended use. In these processing machines, the resin film is conveyed by running between rolls whose surfaces are made of metal or rubber. Since the roll and the resin film are in direct contact with each other, when the friction coefficient of the contact surface of the resin film is large, a difference occurs between the transport speed of the resin film and the rotation speed of the roll. As a result, the surface of the resin film may be scratched or the running of the resin film may become unstable. Therefore, a method has been proposed in which the resin film contains an inorganic filler to roughen the surface of the resin film to reduce the contact surface with the roll and reduce friction.

However, in recent years, from the viewpoint of improving productivity, it has been required to increase the traveling speed of the resin film, and the friction reducing effect is not sufficient only by roughening the film surface by a physical method as in the past. , There is a risk of impairing printability due to excessive roughening. Further, the roughening of the film surface alone causes a problem that the coefficient of friction increases under high humidity.

On the other hand, a method of incorporating inorganic particles and long-chain fatty acid-based bisamide in a polyamide film has been proposed (Patent Document 1). However, although it is possible to suppress an increase in the dynamic friction coefficient under high humidity by containing an aliphatic amide, it is difficult to control the amount of bleed-out, so there are concerns about roll contamination and deterioration of printability.

On the other hand, a biaxially stretched polyamide film in which a coat layer containing a wax having a long-chain alkyl group and spherical fine particles is laminated on a polyamide film has been proposed (Patent Document 2). According to this film, by providing a coat layer containing a slip agent and particles, a predetermined effect can be obtained with a smaller amount than when they are contained in a resin film. However, the addition effect of the spherical fine particles is small when the particle size is small with respect to the thickness of the coating layer. On the other hand, when the particle size of the spherical fine particles is larger, the risk of the fine particles slipping or falling off increases. Further, when high-definition printing is required, if the surface roughness is large, printing omission or the like may occur and the printing accuracy may be lowered.

As described above, in the prior art, if the film is slippery, the printability is sacrificed, but if the printability is improved, the film becomes difficult to slip, so it is difficult to improve both at once. It is said that.

By the way, in recent years, as an application of polyamide film in the industrial field, there is an exterior material of a lithium ion battery. Even in such applications, the slipperiness of the film becomes a problem.

Conventionally, the metal can type has been the mainstream as the exterior material for lithium-ion batteries. However, it has been pointed out that the metal can type has drawbacks such as low degree of freedom in shape and difficulty in weight reduction. Therefore, it has been proposed to use a laminate composed of a base material layer (polyamide film) / metal foil layer (aluminum foil layer) / sealant layer as an exterior body. Such a laminate has become widely used because it is more flexible than a metal can, has a high degree of freedom in shape, can be made lighter by thinning, and is easily miniaturized. ing.

Then, various products such as containers can be obtained by processing the above-mentioned laminate into a predetermined shape by cold molding. The slipperiness of the film is one of the physical properties of the film that affects the moldability during cold molding. For example, when a laminate having a polyamide film as the outermost layer is cold-molded, the polyamide film and the molding die come into contact with each other. Therefore, if the polyamide film is not slippery (that is, the friction coefficient is large), the molding die is used. When pushed in, the surface of the laminate is wrinkled, and the laminate is more likely to cause delamination. Moreover, it is difficult to uniformly mold the entire laminate, and uneven thickness occurs, so that there is a concern that pinholes may occur. In particular, these problems become even more pronounced when cold forming is performed under high humidity. In this respect, the slipperiness of the film is also required to be humidity independent.

JP-A-2002-348465 JP-A-2015-168125

From the above, there is a demand for a polyamide film having excellent slipperiness regardless of humidity, excellent in cold formability or various workability, and capable of performing high-definition printing. However, such a film has not yet been developed.

Therefore, it is a main object of the present invention to provide a polyamide-based laminated film having both high slipperiness and good printability.

As a result of diligent research to solve the above problems, the present inventor has found that the above object can be achieved by adopting a specific layer structure including a polyamide film and a specific resin layer. Has been completed.

That is, the present invention relates to the following polyamide-based laminated film and a method for producing the same.
1. 1. A laminated film containing a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant laminated on at least one surface of the film.
(1) The glass transition temperature of the polyurethane resin is 50 ° C. or higher.
(2) The arithmetic mean height (Ra) of the surface of the polyurethane resin layer is 0.010 to 0.060 μm, and the coefficient of dynamic friction of the surface of the polyurethane resin layer under a 20 ° C. × 90% RH environment is 0. 40 or less,
A polyamide-based laminated film characterized by this.
2. Item 2. The polyamide-based laminated film according to Item 1, wherein the surface of the polyurethane resin layer has a coefficient of dynamic friction of 0.30 or less under a 23 ° C. × 50% RH environment.
3. 3. Item 2. The polyamide-based laminated film according to Item 1, wherein the polyurethane resin layer has a thickness of 0.005 to 0.150 μm.
4. A laminate for food packaging containing the polyamide-based laminate according to any one of Items 1 to 3.
5. A laminate for cold molding containing the polyamide-based laminate film according to any one of Items 1 to 3.
6. A method for producing a polyamide-based laminated film containing a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant on at least one surface of the film.
(1) A sheet molding step of obtaining an unstretched sheet by molding a melt-kneaded product containing a polyamide resin into a sheet.
(2) A stretching step of obtaining a biaxially stretched film by MD stretching and TD stretching of the unstretched sheet, and (3) any one of the unstretched sheet, MD stretched film, TD stretched film or biaxially stretched film. A method for producing a polyamide-based laminated film, which comprises a coating step of applying a water-based coating liquid containing a polyurethane resin and an organic lubricant on one surface.
7. Item 6. The production method according to Item 6, wherein the water-based coating liquid is a mixed liquid of a dispersion liquid of a polyurethane resin and a dispersion liquid of an organic lubricant having a particle size of 0.010 μm to 0.500 μm.
8. The stretching step is carried out by simultaneous biaxial stretching, and the following formulas (a) and (b);
(A) 0.80 ≦ X / Y ≦ 0.95
(B) 9.8 ≤ X x Y ≤ 11.6
(However, X indicates the stretching ratio in the MD direction, and Y indicates the stretching ratio in the TD direction.)
Item 6. The production method according to Item 6, wherein both of the above conditions are satisfied.
9. The stretching step is carried out by sequential biaxial stretching, and the following formulas (a) and (b);
(A) 0.85 ≤ X / Y ≤ 0.95
(B) 8.5 ≤ X x Y ≤ 9.5
(However, X indicates the stretching ratio in the MD direction, and Y indicates the stretching ratio in the TD direction.)
Item 6. The production method according to Item 6, wherein both of the above conditions are satisfied.

According to the present invention, it is possible to provide a polyamide-based laminated film having both high slipperiness and good printability. That is, in the present invention, it is possible to simultaneously improve slipperiness and printability (particularly ink transferability from a plate), which are mutually contradictory characteristics in the prior art.

Since the polyamide-based laminated film of the present invention has a low arithmetic mean height (Ra) of the polyurethane resin layer, high-definition printing can be performed. At the same time, even though the Ra is small, the coefficient of dynamic friction under high humidity is small, so that stable slipperiness can be exhibited without depending on the humidity. As a result, the polyamide-based laminated film of the present invention can be suitably used in various processes in addition to being suitable for transport by rolls.

In particular, since it is a polyurethane resin layer containing a polyurethane resin, which is an organic substance, as a main component, it has excellent ink adhesion, so that it can exhibit excellent printability. In addition to this, since the flexibility of the polyurethane resin layer is relatively good, it is possible to follow the dimensional change of the polyamide film in, for example, a boiling or retort treatment step. Therefore, when processing such as molding (particularly cold molding) using the polyamide-based laminated film of the present invention, it is possible to effectively suppress or prevent the occurrence of delamination and the like.

Further, the polyamide-based laminated film of the present invention is molded because it has good followability with the aluminum foil and has little friction with the molding die even when laminated with the aluminum foil and cold-molded. Due to its excellent properties, it is possible to obtain a molded product having no delamination or pinholes.

According to the method for producing a polyamide-based laminated film of the present invention, the polyamide-based laminated film of the present invention can be obtained more reliably and with good productivity.

It is a figure which shows the layer structure example of the polyamide-based laminated film of this invention. It is a figure which shows the embodiment of the polyamide-based laminated film of this invention.

Embodiment of the invention

1. 1. Polyamide-based laminated film The polyamide-based laminated film of the present invention (the film of the present invention) is a laminated film containing a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant laminated on at least one surface of the film. And
(1) The glass transition temperature of the polyurethane resin is 50 ° C. or higher.
(2) The arithmetic mean height (Ra) of the surface of the polyurethane resin layer is 0.010 to 0.060 μm, and the coefficient of dynamic friction of the surface of the polyurethane resin layer under a 20 ° C. × 90% RH environment is 0. 40 or less,
It is characterized by that.

A. Layer structure of the film of the present invention As described above, the film of the present invention is a polyurethane resin layer containing a polyamide film, a polyurethane resin laminated on at least one surface of the film, and an organic lubricant (hereinafter, simply "polyurethane resin"). The basic structure is a laminated film containing "layers"). That is, the basic configuration is a laminated structure in which a polyurethane resin layer is formed so as to be adjacent to one side or both sides of the polyamide film without using an adhesive layer.

FIG. 1 shows an example of the layer structure of the film of the present invention. FIG. 1A shows a laminate (film of the present invention) 10 in which a polyurethane resin layer 12 is laminated on one side of a polyamide film 11. FIG. 1B shows a laminate (film of the present invention) 10'in which polyurethane resin layers 12 and 12 are laminated on both sides of the polyamide film 11. In each of these cases, the polyurethane resin layer is arranged as the outermost surface layer (outermost layer) (layer exposed to the outside). By exposing the polyurethane resin layer as the outermost surface layer in this way, for example, when a package (bag body or the like) made of the film of the present invention is produced with the polyurethane resin layer facing outward, the contents of the package. Can be protected from the outside. Therefore, in the film of the present invention, it is desirable that the polyurethane resin layer is arranged as the outermost surface layer (outermost layer) (layer exposed to the outside) on at least one of the front surface and the back surface.

In the film of the present invention, as long as the polyurethane resin layer is directly formed on the surface of the polyamide film as described above and at least one polyurethane resin layer is arranged as the outermost surface layer, other films are required. The layers may be further laminated. For example, barrier layer (gas barrier layer, water vapor barrier layer, etc.), printing layer, adhesive layer, heat fusion layer (sealant layer, heat seal layer), primer layer (anchor coat layer), antistatic layer, vapor deposition layer, ultraviolet rays. Examples include an absorption layer and an ultraviolet blocking layer.

FIG. 2 shows a layer configuration example of a polyamide-based laminated film in which other optional layers are further laminated in addition to the polyamide film and the polyurethane resin layer.

FIG. 2A shows a laminated body 20 in which a barrier layer 13 and a heat fusion layer 14 are further laminated on one side of the laminated body 10 of FIG. 1A. In this laminate 20, the barrier layer 13 and the heat-sealing layer 14 are laminated on the surface of the polyamide film 11 on which the polyurethane resin layer 12 is not formed, so that the polyurethane resin layer 12 is exposed as the outermost surface layer. It is maintained.

FIG. 2B shows a laminate 20'in which a barrier layer 13 and a heat fusion layer 14 are further laminated on one side of the laminate 10'of FIG. 1B. In this laminate 20', a barrier layer 13 and a heat-sealing layer 14 are laminated on one of the polyurethane resin layers 12 of the polyamide film 11, and the other polyurethane resin layer 12 is exposed as the outermost surface layer. Is maintained.

Further, as shown in FIG. 2A or FIG. 2B, when the film of the present invention has a heat-sealing layer 14, the heat-sealing layer 14 is arranged as the outermost surface layer. That is, when the film of the present invention has the heat-sealing layer 14, it is preferable to adopt a layer structure in which one outermost surface layer is the polyurethane resin layer 12 and the other outermost surface layer is the heat-sealing layer 14.

In the following, in addition to the polyamide film and the polyurethane resin layer constituting the film of the present invention, arbitrary layers will be described respectively.

A-1. Polyamide film The polyamide film serves as a base material (core material) for the film of the present invention, and is usually provided in the form of a preformed film. As the polyamide film itself, a known or commercially available one can be used. Further, a film produced by a known production method can also be used.

The polyamide film may have a single-layer structure, or may have a multilayer structure in which two or more polyamide films are laminated. Further, in the case of a multi-layer structure, each layer may have the same composition or different compositions.

The polyamide film is mainly composed of a polyamide resin, but other components may be contained as long as the effects of the present invention are not impaired. In this case, the content ratio of the polyamide resin in the polyamide film is not limited, but is usually about 70 to 100% by mass, particularly preferably 90 to 99.5% by mass, and among them, 95 to 99. It is more preferably mass%.

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

Examples of lactams include ε-caprolactam, enantractum, capril lactam, lauryl lactam and the like.

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

Examples of dibasic acids include adipic acid, glutaric acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, undecandionic acid, dodecadioic acid, hexadecadioic acid, eikosandioic acid, eikosadiendioic acid, 2, Examples thereof include 2,4-trimethylazipic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and xylylene dicarboxylic acid.

Examples of diamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, 2,2,4 (or 2,4,4). Examples thereof include -trimethylhexamethylenediamine, cyclohexanediamine, bis- (4,4'-aminocyclohexyl) methane, and m-xylylenediamine.

In the present invention, as these compounds (starting materials), biomass-derived compounds can also be used from the viewpoint of environmental protection and the like.

As a polymer obtained by polycondensing these monomer components or a copolymer thereof, for example, nylon 6, 7, 11, 12, 6.6, 6.9, 6.11, 6.12, 6T, 9T. , 10T, 6I, MXD6 (polymethylylene adipamide), 6 / 6.6, 6/12, 6 / 6T, 6 / 6I, 6 / MXD6 and the like can be used. These can be used alone or in combination of two or more. Among these, aliphatic polyamide resins such as nylon 6, nylon 6, 6 are preferable, and among them, nylon 6 is more preferably contained in that the balance between heat resistance and mechanical properties is excellent.

The relative viscosity of the polyamide resin used in the polyamide film is not limited, but is usually preferably about 1.5 to 5.0, and particularly preferably 2.0 to 4.0. More preferred. If the relative viscosity is less than 1.5, the mechanical properties of the resulting film are likely to be significantly reduced. On the other hand, if the relative viscosity exceeds 5.0, the film-forming property of the film tends to be hindered. The relative viscosity is a value measured by using a Ubbelohde viscometer in a sample solution (liquid temperature 25 ° C.) in which polyamide is dissolved in 96% sulfuric acid so as to have a concentration of 1.0 g / dl. In the present invention, the relative viscosity of the polyamide film in the finally obtained film of the present invention is also preferably within the above range.

As described above, the polyamide film may contain other components in addition to the polyamide resin as long as the effects of the present invention are not impaired. Examples of other components include known or commercially available additives. More specifically, metals (metal ions), pigments, heat stabilizers, antioxidants, weather resistant agents, flame retardants, plasticizers, mold release agents, strengthening agents (fillers) and the like are exemplified. In particular, as the heat stabilizer or antioxidant, hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides and the like can be preferably used.

Further, the polyamide film may contain a lubricant if necessary. Specific examples of lubricants include clay, talc, calcium carbonate, zinc carbonate, wallastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, magnesium aluminosilicate, glass balloon, carbon black, and oxidation. Inorganic lubricants such as zinc, antimony trioxide, zeolite, hydrotalside, layered silicate, erucic acid amide, oleic acid amide, stearic acid amide, ethylene bisstearic acid amide, ethylene biss ethylene bisoleic acid amide, hexamethylene Examples thereof include organic lubricants such as bisstearic acid amide and hexamethylene bisoleic acid amide methylene bisstearic acid amide. These can be used alone or in combination of two or more.

The thickness of the polyamide film is not particularly limited, but is generally preferably 4 to 35 μm, and more preferably 5 to 25 μm. If the thickness is less than 4 μm, the mechanical strength tends to be insufficient and the moldability is lowered. On the other hand, if the thickness exceeds 35 μm, the amount of raw materials used may increase or the productivity may decrease.

Further, the polyamide film is preferably stretched from the viewpoint of mechanical strength. That is, it is preferable to have a structure having orientation. In this case, either uniaxial stretching or biaxial stretching may be used, but it is particularly preferable to have orientation due to biaxial stretching. The draw ratio can be appropriately set within the range shown later.

The polyamide film has a surface that has been subjected to known surface treatments such as corona treatment, plasma treatment, ozone treatment, etc. on at least one side in order to improve the adhesion between each layer constituting the laminated body when formed into a laminated body. Is preferable.

A-2. Polyurethane resin layer The polyurethane resin layer constituting the film of the present invention is mainly a layer for exhibiting slipperiness and printability, and contains a polyurethane resin and an organic lubricant.

The polyurethane resin is, for example, a polymer obtained by reacting a polyfunctional isocyanate with a hydroxyl group-containing compound. More specifically, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane isocyanate and polymethylene polyphenylene polyisocyanate, or polyfunctional isocyanates such as aliphatic polyisocyanates such as hexamethylene diisocyanate and xylene isocyanate, and polyether polyols, A urethane resin obtained by reacting with a hydroxyl group-containing compound such as a polyester polyol, a polyacrylate polyol, or a polycarbonate polyol can be exemplified. As these polyurethane resins themselves, known or commercially available ones can be used.

Further, in the polyurethane resin, various functional groups such as an anionic functional group, a cationic functional group and a nonionic functional group may be introduced as long as the effects of the present invention are not impaired. In particular, it is preferable that an anionic functional group is contained from the viewpoint of dispersibility in the state of the coating liquid. Examples of the anionic functional group include a carboxyl group and a sulfone group.

The method for introducing an anionic functional group into the polyurethane resin is not particularly limited, and for example, a) a method using a diol having an anionic functional group as a polyol component, b) a diol having an anionic functional group as a chain extender. And the like. Examples of the diol having an anionic functional group include glyceric acid, dioxymaleic acid, dioxyfumaric acid, tartaric acid, dimethylol propionic acid, dimethylol butanoic acid, 2,2-dimethylol valeric acid, and 2,2-di. In addition to aliphatic carboxylic acids such as methylolpentanoic acid, 4,4-di (hydroxyphenyl) valeric acid, and 4,4-di (hydroxyphenyl) butyric acid, aromatic carboxylic acids such as 2,6-dioxybenzoic acid Can be mentioned.

The polyurethane resin layer preferably has a crosslinked structure. The crosslinked structure can be formed by a) a method of reacting with a polyurethane resin and adding a crosslinking agent capable of forming a crosslinked structure, b) a method of using a polyurethane resin containing a reactive group in the skeleton, or the like. ..

As the above-mentioned cross-linking agent, a cross-linking agent capable of reacting with a polyurethane resin terminal group is preferable. As a result, the number of polar groups in the molecule of the polyurethane resin can be reduced, so that the slipperiness can be further improved. Specific examples of the cross-linking agent include isocyanate, oxazoline, carbodiimide, melamine resin and the like. Among these, it is preferable to use a melamine resin from the viewpoint of reactivity, economy and the like. A typical melamine resin is tri (alkoxymethyl) melamine. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like. One kind or two or more kinds of these melamine resins can be used.

When a cross-linking agent is used, the amount to be added may be appropriately set depending on the type of the cross-linking agent used and the like, but usually it can be set within the range of 1 to 10 parts by mass with respect to 100 parts by mass of the polyurethane resin.

The glass transition temperature of the polyurethane resin needs to be 50 ° C. or higher, particularly preferably 70 ° C. or higher, and more preferably 90 ° C. or higher, particularly from the viewpoint of improving slipperiness. When the glass transition temperature is less than 50 ° C., it may exceed the range of the dynamic friction coefficient specified in the present invention, and the slipperiness also tends to decrease particularly under high humidity. The upper limit of the glass transition temperature is not limited, but can be, for example, about 150 ° C.

The content of the polyurethane resin in the polyurethane resin layer is not particularly limited, but is usually about 50 to 98% by weight (particularly 70 to 95% by weight), but is not limited thereto.

In the present invention, the organic lubricant has a function of simultaneously enhancing both slipperiness and printability, which are contradictory to each other, by coexisting with a polyurethane resin having a glass transition temperature of 50 ° C. or higher.

The organic lubricant is not particularly limited, and includes various organic compounds such as hydrocarbon-based, fatty acid-based, aliphatic bisamide-based, and metal soap-based, as well as resin-based lubricants such as phenol resin, melamine resin, and polymethylmethacrylate resin. Examples include organic lubricants.

Among these organic lubricants, in the present invention, an organic lubricant having a melting point of 50 to 200 ° C. is particularly preferable. The organic lubricant is not particularly limited, but it is preferable to use at least one of polyethylene wax, a silicon-acrylic copolymer, a silicon-urethane copolymer, and an aliphatic amide. Since these organic lubricants can be liquid, the smoothness of the surface of the polyurethane resin layer is not impaired. Further, since it is added to the polyurethane resin layer, it is possible to obtain the effect as a lubricant with a smaller addition amount, and it becomes easier to control the bleed-out amount. Commercially available products can also be used as these organic lubricants.

From the viewpoint of slipperiness, the polyethylene wax preferably contains high crystalline polyethylene as a main component, preferably has a melting point of 90 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 120 ° C. or higher. Most preferably. As long as the melting point is 90 ° C. or higher, polyethylene alone, a polyethylene copolymer, or a mixture of polyethylene and a polyethylene copolymer may be used. The upper limit of the melting point can be, for example, about 150 ° C.

For the silicon-acrylic copolymer and the silicon-urethane copolymer, it is preferable that the side chain is polymerized with respect to the main chain by graft polymerization from the viewpoint of compatibility with the polyurethane resin. If the main chain is a silicon component, the side chain is preferably an acrylic or urethane component, and if the main chain is an acrylic or urethane component, the side chain is preferably a silicon component.

The aliphatic amide preferably has a carbon number of C8 or more and 20 or less, particularly preferably C12 or more and C18 or less, and more preferably C16 or more and C18 or less. If it exceeds C20, printability may decrease. If it is less than C8, the effect of improving slipperiness may not be sufficient. Specific examples of such fatty acid amide include saturated fatty acids such as stearic acid (C18) and monoamides of unsaturated fatty acids such as oleic acid (C18). Among these, at least one of stearic acid amide and ethylene bisstearic acid amide is preferable because it is compatible with the water-based coating liquid.

The organic lubricant may be contained in the polyurethane resin layer, but may be particularly unevenly distributed on the surface of the polyurethane resin layer. When the organic lubricant is unevenly distributed on the surface of the polyurethane resin layer, slipperiness can be reliably imparted with less organic lubricant.

The content (solid content ratio) of the organic lubricant is preferably 5 to 30 parts by mass, particularly 10 to 30 parts by mass, based on 100 parts by mass of the polyurethane resin from the viewpoint of improving slipperiness and printability. It is more preferably parts, and most preferably 15 to 30 parts by mass. If the amount of the organic lubricant exceeds 0 parts by mass, the printability is deteriorated and the effect of lowering the dynamic friction coefficient is also reduced. When the amount of the organic lubricant is less than 5 parts by mass, the printability is good, but it becomes difficult to reduce the dynamic friction coefficient.

The polyurethane resin layer may contain additives other than the organic lubricant, if necessary, as long as its properties are not significantly impaired. For example, additives such as surfactants, defoamers, heat stabilizers, antioxidants, reinforcing materials, pigments, deterioration inhibitors, weather resistant agents, flame retardants, plasticizers, and mold release agents may be contained.

The thickness of the polyurethane resin layer is not particularly limited, but is usually preferably 0.005 to 0.150 μm, more preferably 0.010 to 0.150 μm, and 0.020 among them. Most preferably, it is ~ 0.100 μm. If the thickness of the polyurethane resin layer is less than 0.005 μm, it becomes difficult to form a polyurethane resin layer having a uniform film thickness on the polyamide film, and thus it becomes difficult to obtain sufficient slipperiness. On the other hand, if the thickness of the polyurethane resin layer exceeds 0.150 μm, the slipperiness improving effect of the polyurethane resin layer is saturated, which is economically disadvantageous.

A-3. Other Layers As described above, the film of the present invention can be laminated with various layers as needed, in addition to the polyamide film and the polyurethane resin layer. That is, the polyamide-based laminated film of the present invention includes a laminated body including a basic structure of a polyamide film and a polyurethane resin layer, and in which other layers are laminated. Therefore, in the present specification, a laminated body in which other layers are laminated in addition to the basic configuration (the laminated film) is also referred to as a “laminated body”.

Such a laminate can be suitably used as a packaging laminate for, for example, food packaging, battery packaging (exterior material), and the like. Further, since the film of the present invention is also suitable for cold molding (for example, molding temperature of 50 ° C. or lower) as a laminate for cold molding, it can also be used in a method for producing a molded product including a step of cold molding the film of the present invention. Applicable. As described above, the present invention includes a polyamide-based laminated film particularly used for food packaging or cold molding.

As the layer other than the above basic composition, the same layer as that used for known packaging materials or the like can be used. For example, a barrier layer, a primer layer, a heat-sealing layer, an adhesive layer, a clear layer, a printing layer and the like can be mentioned. As these, the same ones as the known laminates can be adopted, but it is desirable to set the barrier layer and the heat-sealing layer as follows.

The barrier layer has excellent barrier properties (gas barrier properties, especially oxygen barrier properties, etc.), and includes, for example, known metal foils, metal vapor-deposited films, transparent vapor-deposited films, and other inorganic barrier layers, polyvinyl alcohol, and the like. Examples thereof include various barrier films of an organic coat layer such as an ethylene-vinyl alcohol copolymer. Among these, metal foils such as aluminum foils and copper foils are preferable from the viewpoint of versatility, and aluminum foils are particularly preferable.

When a metal foil is used as the barrier layer, the thickness of the metal foil is not particularly limited, but is usually about 5 to 200 μm, more preferably 5 to 150 μm, and most preferably 7 to 50 μm. ..

Further, one or both surfaces of the metal foil may be surface-treated to enhance adhesiveness, corrosion resistance, and the like. Examples of the surface treatment include chemical conversion treatment and chromate treatment. In particular, these surface treatments are preferably applied to the surface on the side in contact with the heat fusion layer.

The heat-sealing layer is not particularly limited as long as it can be heat-sealed, and known ones can be used, and examples thereof include a polyvinyl chloride film and a polyolefin film. Examples of polyolefins include polyethylene, polypropylene, polyethylene, copolymers containing polypropylene as a main component, and acid-modified products thereof. As the heat-sealing layer, either a stretched film or a non-stretched film can be used, and the molten resin may be directly laminated.

The thickness of the heat-sealing layer is not particularly limited, but is usually preferably 20 to 200 μm, and more preferably 30 to 100 μm.

Further, when laminating these, for example, it is possible, but not limited to, laminating using a known adhesive or the like.

In the present invention, as a method for adhering the polyamide film and the metal foil, for example, a dry laminate, a thermal laminate, or the like using a two-component type urethane adhesive can be preferably adopted.

Further, as a method for adhering the metal foil and the heat-sealing layer, for example, a dry laminate, a heat laminate, an extrusion laminate, a sandwich laminate method and the like can be preferably used.

An anchor coat layer, a primer layer, or the like may be provided in advance on the surface of the film, metal foil, or heat-sealing layer on which the adhesive layer is formed, as long as the effects of the present invention are not impaired. good.

In the present invention, when other layers are laminated, particularly by arranging the polyurethane resin layer on the outermost layer, slipperiness and printability are excellent. Therefore, various applications such as packaging for foods, electronic and electrical parts, etc. It can also be suitably used for industrial applications.

As the film of the present invention, as shown in FIG. 2A or FIG. 2B, for example, a laminate including a polyurethane resin layer 12 / polyamide film 11 / metal foil 13 / heat-sealing layer 14, polyurethane resin layer 12 / polyamide film 11 / polyurethane resin. A laminate or the like containing the layer 12 / metal foil 13 / heat-sealing layer 14 is effective as a packaging material such as an exterior material for a battery.

B. Characteristics of the film of the present invention The thickness of the film of the present invention is not particularly limited and can be appropriately set depending on, for example, the intended use and method of use. For example, when the film of the present invention is used as an exterior material of a battery, the thickness of the laminate 10 or 10'in FIG. 1 can be, for example, in the range of about 10 to 25 μm, or in the range of, for example, 15 to 25 μm. It can, but is not limited to this.

The film of the present invention has a dynamic friction coefficient of the surface of the polyurethane resin layer under a 20 ° C. × 90% RH environment of usually 0.40 or less, preferably 0.35 or less, and more preferably 0.30 or less. In the film of the present invention, the lower limit of the dynamic friction coefficient in an environment of 20 ° C. × 90% RH is not particularly limited, but is usually about 0.20. When the coefficient of kinetic friction in an environment of 20 ° C. × 90% RH is 0.40 or less, excellent workability and printability can be obtained more reliably even in high humidity.

Further, the film of the present invention has a dynamic friction coefficient of the surface of the polyurethane resin layer under a 23 ° C. × 50% RH environment of usually 0.30 or less, preferably 0.25 or less, from the viewpoint of improving moldability and printability. It is more preferably 0.20 or less. The lower limit of the dynamic friction coefficient in an environment of 23 ° C. × 50% RH is not particularly limited, but is usually about 0.10.

Further, in the film of the present invention, the arithmetic mean height (Ra) calculated from the measurement of the two-dimensional surface roughness of the surface of the polyurethane resin layer needs to be usually 0.010 to 0.060 μm, particularly 0.010 to 0.060 μm. It is preferably 0.055 μm, more preferably 0.020 to 0.050 μm, and most preferably 0.010 to 0.040 μm. If the Ra exceeds 0.060 μm, the unevenness of the surface of the resin layer becomes large, so that printing omission may occur, and it becomes difficult to perform high-definition printing.

Further, the contact angle of water on the surface of the polyurethane resin layer of the film of the present invention is preferably 82 ° to 98 °, more preferably 86 ° to 98 °, from the viewpoint of improving slipperiness or printability. Among them, 90 ° to 98 ° is most preferable. If the contact angle is less than 82 °, the frictional resistance becomes large and the slipperiness may decrease. Further, if the contact angle exceeds 98 °, the printability may be lowered due to the deterioration of the ink adhesion. Further, since the surface of the polyurethane resin layer of the film of the present invention has few irregularities, it is possible to suppress variations in the measured contact angle values.

2. Production of Polyamide-based Laminated Film The film of the present invention is a method for producing a polyamide-based laminated film containing, for example, a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant laminated on at least one surface of the film. And
(1) A sheet molding step of obtaining an unstretched sheet by molding a melt-kneaded product containing a polyamide resin into a sheet.
(2) A stretching step of obtaining a biaxially stretched film by MD stretching and TD stretching of the unstretched sheet, and (3) any one of the unstretched sheet, MD stretched film, TD stretched film or biaxially stretched film. It can be suitably produced by a method for producing a polyamide-based laminated film, which comprises a coating step of applying a water-based coating liquid containing a polyurethane resin and an organic lubricant on one surface.

Sheet molding step In the sheet molding step, an unstretched sheet is obtained by molding a melt-kneaded product containing a polyamide resin into a sheet.

The unstretched sheet can be obtained by molding a melt-kneaded product containing a polyamide resin into a film. The preparation of the melt-kneaded product itself may be carried out according to a known method. For example, it can be produced by molding a melt-kneaded product obtained by melting a resin composition containing a polyamide-based resin into a film shape (sheet shape). This can be done by using a known or commercially available device. For example, a melt extruder with a T-die can be used. That is, first, the starting material (for example, pellet-shaped raw material) is supplied to the hopper, plasticized and melted by a melt extruder, and the melt-kneaded product is extruded into a sheet from a T-die attached to the tip of the extruder and cooled by a cast roll. Solidify. At this time, the melt-kneaded product can be pressed against the cast roll by air to obtain an unstretched sheet.

In addition to the polyamide resin, various additives can be added to the above resin composition as needed. Examples of the additive include an additive added to the polyamide film.

The average thickness of the unstretched sheet in this case is not particularly limited, but is generally about 15 to 250 μm, and particularly preferably 50 to 235 μm. By setting within such a range, the stretching step can be carried out more efficiently.

Stretching Step In the stretching step, the unstretched sheet is MD-stretched and TD-stretched to obtain a biaxially stretched film.

It is preferable to preheat the unstretched sheet or the uniaxially stretched film prior to the stretching step. The preheating temperature is not limited, but is preferably set within ± 50 ° C. of the stretching temperature. By preheating, a biaxially stretched film having good physical properties can be obtained more reliably. The preheating time depends on the preheating temperature and the like, but is usually preferably about 0.5 to 5 seconds.

The method of preheating is not particularly limited. For example, a method of setting the temperature of the hot air blown on the film traveling in the preheating zone of the stretching machine to the above temperature range can be preferably adopted.

Further, the method of setting the stretching temperature to the above temperature is not limited, but it is preferable to set the temperature of the hot air blown to the film traveling in the stretching zone of the stretching machine to the above temperature range. In this case, the time for the polyamide film to travel in the stretch zone is usually preferably about 0.5 to 5 seconds.

As the stretching method, when the film of the present invention is finally obtained by biaxial stretching, a simultaneous biaxial stretching method or a sequential biaxial stretching method can be adopted. Further, as the classification by the stretching device, for example, there are a tubular method, a tenter method and the like, and any of them can be applied. In the present invention, the stretching method by the tenter method is particularly preferable in terms of quality stability and dimensional stability. Therefore, the tenter type simultaneous biaxial stretching method or the tenter type sequential biaxial stretching method can be preferably adopted. Examples of the tenter type biaxial stretching method include a pantograph type tenter, a screw type tenter, and a linear motor type tenter.

When the simultaneous biaxial stretching method is adopted as the stretching method, an unstretched sheet is coated with a water-based coating liquid containing a urethane resin and an organic lubricant, and then biaxially stretched in the MD direction and the TD direction at the same time. , The film of the present invention in which a urethane resin layer is formed on a predetermined biaxially stretched polyamide film can be obtained.

When the sequential biaxial stretching method is adopted, a water-based coating liquid containing a urethane resin and an organic lubricant is previously applied to a film uniaxially stretched in the MD direction or the TD direction, and then substantially orthogonal to the uniaxial stretching direction. By stretching in the direction (TD direction or MD direction), the film of the present invention in which a urethane resin layer is formed on a predetermined biaxially stretched polyamide film can be obtained.

The stretching ratio is not particularly limited, but usually it may be stretched to about 2.0 to 4.5 times in the MD direction and the TD direction, respectively. In this case, the draw ratios in the MD direction and the TD direction may be the same or different from each other. By such stretching, a stretched film having good physical properties such as tensile strength and tensile elongation can be obtained.

The polyamide-based laminated film of the present invention needs to satisfy the following conditions (a) and (b) at the same time in order to keep the arithmetic mean height (Ra) of the polyurethane resin layer within the range specified in the present invention. .. In the mathematical formulas (a) and (b) below, X indicates a stretching ratio in the MD direction, and Y indicates a stretching ratio in the TD direction. Further, X / Y indicates the draw ratio of the MD draw ratio (X) and the TD draw ratio (Y). X × Y indicates the surface magnification.

When performing simultaneous biaxial stretching, in particular (a) 0.80 ≦ X / Y ≦ 0.94
(B) 9.8 ≤ X x Y ≤ 11.6
It is preferable to satisfy.

When sequentially biaxial stretching is carried out, in particular, (a) 0.85 ≦ X / Y ≦ 0.95
(B) 8.5 ≤ X x Y ≤ 9.5
It is preferable to satisfy.

The stretching temperature is not limited, and can be appropriately set within the range of 225 ° C. or lower (preferably 40 to 220 ° C.) depending on, for example, the stretching method, the application of the film of the present invention, the mode of use, and the like.

It is preferable that the film stretched in the stretching step is further heat-treated. The heat treatment temperature is not particularly limited, but is usually preferably about 190 to 220 ° C, and more preferably 195 to 215 ° C. If the heat treatment temperature is less than 190 ° C., the film has a large shrinkage rate, which is not preferable as a polyamide film for packaging. Further, when an organic lubricant, a cross-linking agent or the like is added, the former does not bleed out sufficiently, and the latter does not sufficiently proceed with the cross-linking reaction, so that the effect of the addition may not be sufficiently obtained. On the other hand, when the heat treatment temperature exceeds 220 ° C., the strength of the polyamide film decreases. If the heat treatment does not sufficiently proceed with the bleed-out of the organic lubricant or the cross-linking reaction of the cross-linking agent, an aging treatment may be performed after the stretching is completed. The heat treatment time can be appropriately set according to the heat treatment temperature and the like, but is usually preferably about 1 to 15 seconds.

The heat treatment method is not particularly limited, and for example, a method of blowing hot air, a method of irradiating infrared rays, a method of irradiating microwaves, and the like can be adopted. Among these, the method of blowing hot air is preferable from the viewpoint that the heating can be performed uniformly and accurately. For example, the heat fixing process can be performed by blowing hot air set in the above temperature range onto the film traveling in the heat fixing zone of the stretching machine.

Coating step In the coating step, a water-based coating liquid containing a polyurethane resin and an organic lubricant is applied on the surface of any one of the unstretched sheet, MD stretched film, TD stretched film and biaxially stretched film.

The method for preparing the water-based coating liquid can be carried out by dissolving or dispersing the polyurethane resin and the organic lubricant in the water-based medium. By using the water-based coating liquid, the desired film of the present invention can be efficiently obtained, and it is also advantageous in terms of workability, environment and the like.

In the present invention, the aqueous medium is water or a mixed solvent containing water as a main component (usually, water is a liquid of 50% by mass or more). As the mixed solvent, a mixed solvent of water and a water-soluble organic solvent can be used. Examples of the water-soluble organic solvent include, but are not limited to, alcohols such as methanol, ethanol and isopropanol, and ketones such as acetone and methyl ethyl ketone (MEK). The water-soluble organic solvent can be used alone or in combination of two or more. By mixing the water-soluble organic solvent, it is possible to obtain effects such as improving the applicability to the polyamide film and shortening the drying process. In this respect, when additives such as a cross-linking agent are used in addition to polyurethane resin and the like, these additives are preferably water-based (aqueous solution or aqueous dispersion (emulsion)).

When preparing the water-based coating liquid, the mixing order of each component such as polyurethane resin, organic lubricant, and water-based medium is not limited, and for example, a method of adding the organic lubricant to a pre-prepared aqueous dispersion or aqueous solution of polyurethane resin is suitable. A water-based coating solution can be prepared. Hereinafter, this method will be described as a typical example.

The polyurethane resin used for the water-based coating liquid is not particularly limited, but as shown above, it is preferable to use a polyurethane resin (anionic polyurethane resin) into which an anionic functional group has been introduced. By using an anionic polyurethane resin, it can be more uniformly and stably dispersed in water. As described above, in the present invention, it is preferable to use the polyurethane resin in the form of an aqueous dispersion to prepare a coating liquid.

Furthermore, when dispersing the anionic polyurethane resin in an aqueous medium, it is generally preferable to use a volatile base. The volatile base is not particularly limited, and known ones can be used. More specifically, ammonia, methylamine, ethylamine, dimethylamine, diethylamine, triethylamine, morpholine, ethanolamine and the like are exemplified. Among these, triethylamine is more preferable because it has good liquid stability of the water-dispersible polyurethane resin and has a relatively low boiling point, so that the amount remaining in the primer layer is small.

As the aqueous dispersion of such a polyurethane resin, a known or commercially available one can be used. As commercially available products, for example, as anionic water-dispersible polyurethane resin, "Takelac W-5030", "Takelac WS-4000", "Takelac WS-4022" manufactured by Mitsui Chemicals Polyurethane, and "Hydran AP40F" manufactured by DIC Corporation. Etc. can be used.

Next, an organic lubricant is added and mixed with the aqueous dispersion of polyurethane resin. The type of organic lubricant, the amount of the organic lubricant added, and the like may be the same as those shown above. In this case, the form of the organic lubricant may be one dispersed in a solvent (water or a solvent), or may be used as a simple substance (powder). In particular, in the present invention, it is preferable to use it in the form of a dispersion liquid (for example, an aqueous dispersion liquid) in which an organic lubricant is dispersed in a solvent. Therefore, it is desirable that the water-based coating liquid is a mixed liquid of a dispersion liquid of a polyurethane resin and a dispersion liquid of an organic lubricant.

The particle size of the organic lubricant in the dispersion in this case is not particularly limited, but is usually preferably about 0.010 μm to 0.500 μm, and more preferably 0.010 μm to 0.400 μm. Further, it is particularly preferably 0.010 μm to 0.200 μm, and most preferably 0.010 μm to 0.100 μm. When the particle size is smaller than 0.010 μm, the particles are dispersed very finely in the polyurethane resin layer, so that the printability is improved, but the effect of lowering the dynamic friction coefficient is reduced. On the other hand, when the particle size exceeds 0.500 μm, the effect of lowering the dynamic friction coefficient can be obtained, but the organic lubricant tends to aggregate, so that the printability is lowered.

The particle size of the organic lubricant in the dispersion is determined by a laser diffraction / scattering method (dispersion medium: water) based on the Mie theory using a laser diffraction type particle size distribution measuring device (product name "Mastersizer 3000" manufactured by Malvern Instruments LTD). ) Indicates the median diameter obtained by. In this case, the refractive index of the dispersion medium (water) was set to 1.330. The refractive index of the organic lubricant was 1.500 for polyethylene wax, 1.59 for silicon-acrylic copolymer, 1.49 for silicon-urethane copolymer, and 1.46 for fatty acid amide.

The mixing of the polyurethane resin and the organic lubricant is not particularly limited as long as the organic lubricant can be uniformly dispersed, and can be carried out using a mixing device such as a known or commercially available mixer or kneader. In particular, in the present invention, heating can be appropriately performed, and it can be preferably carried out using a melting pot or the like equipped with a stirrer. The mixing temperature is not particularly limited and can be, for example, about 5 to 40 ° C.

In addition to the polyurethane resin and organic lubricant, the water-based coating liquid may contain other components as long as the effects of the present invention are not impaired. For example, various additives exemplified above can be blended.

As the above additive, in the present invention, a surfactant can be added for the purpose of improving the coatability on the polyamide film. The surfactant is not particularly limited, but is an anionic surface such as polyethylene alkylphenyl ether, polyoxyethylene-fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, alkyl sulfosuccinate and the like. In addition to the activator, a nonionic surfactant such as acetylene glycol can be mentioned.

The content of the surfactant is not particularly limited, but it is generally preferable that the surfactant content is 0.01 to 1% by mass in the water-based coating liquid. Further, it is preferable that the polyamide-based laminated film is volatilized by heat treatment in the manufacturing process.

The solid content concentration of the water-based coating liquid can be appropriately adjusted depending on, for example, the specifications of the coating device used, the drying / heat treatment device, and the like. However, if the coating liquid is too dilute, it takes a long time in the drying process, and the coating thickness after drying becomes too thin, so that a uniform coating cannot be formed and the risk of defects increases. Problems are likely to occur. On the other hand, a water-based coating liquid having an excessively high concentration tends to cause a problem in coatability because the coated surface is difficult to be uniform. Therefore, from such a viewpoint, the solid content concentration of the water-based coating liquid is generally preferably about 5 to 70% by mass.

The method of applying the water-based coating liquid to the polyamide film is not particularly limited, and a known method can be appropriately adopted. For example, gravure roll coating method, reverse roll coating method, wire bar coating method, air knife coating method, curtain coating method, doctor knife method, die coating method, dip coating method, bar coating method, etc., as well as a combination of these methods Can be adopted.

The drying step after coating is not particularly limited, and a known method is used, for example, a drying treatment in a drying atmosphere such as an oven, a drying treatment by contacting with a heat roll, a drying treatment in a stretching machine, and the like. Can be dried. The drying temperature is not limited, but can usually be set in the range of about 30 to 200 ° C. The drying time can be appropriately set depending on the drying temperature and the like, but generally it may be in the range of 0.5 to 60 seconds.

The timing of applying the water-based coating liquid is such that the water-based coating liquid can be applied on the surface of any one of the unstretched sheet, MD stretched film, TD stretched film, and biaxially stretched film. That is, any method such as an in-line coating method and a post-coating method (offline coating method) can be adopted.

In particular, in the present invention, by adopting the in-line coating method, the film thickness can be made thinner and more uniform than the offline coating method, and the productivity is improved, so that a high-quality product can be manufactured at low cost. It becomes possible. In particular, when the in-line coating method is adopted, both slipperiness and printability can be improved. The reason is not clear, but the slipperiness and printability are improved by orienting the molecular chains of the polyurethane resin and promoting the cross-linking reaction or bleed-out of the organic lubricant by performing heat treatment at the same time as stretching by the in-line coating method. It is expected to be better. In particular, it is presumed that the organic lubricant bleeds out to the surface of the stretched film, so that the organic lubricant can be unevenly distributed on the surface of the stretched film, and the stretched film can be modified to have a slippery property even with a relatively small amount of the organic lubricant.

The in-line coating method is not particularly limited as long as the coating film formation by the water-based coating liquid and the stretching of the film can be carried out substantially at the same time. For example, a) After applying the water-based coating liquid to the unstretched sheet, sequentially Alternatively, a method of simultaneous biaxial stretching, b) a method of applying a water-based coating liquid to an MD-stretched uniaxially stretched film and then TD stretching, c) a method of applying a water-based coating liquid to a TD-stretched uniaxially stretched film. , MD stretching method and the like. On the other hand, the post-coating method is a method of forming a coating film with a water-based coating liquid on the film after biaxial stretching.

A preferred embodiment of the in-line coating method in the case of simultaneous biaxial stretching is a method including a step of molding a polyamide resin into a sheet to obtain an unstretched polyamide sheet and then applying a water-based coating liquid. is there. The unstretched polyamide sheet coated with the water-based coating liquid is dried at 50 to 220 ° C., preferably 80 ° C. to 180 ° C., more preferably 120 ° C. to 160 ° C. in the drying step, and then has a stretching temperature of 215 ° C. or lower ( It is preferable to perform simultaneous biaxial stretching under the conditions of a stretching ratio of 2.5 to 3.8 times in both the MD and TD directions (preferably 190 to 215 ° C.). The method of simultaneously biaxially stretching the unstretched polyamide sheet can be performed by a known stretching method. Among them, from the viewpoint of economic efficiency such as productivity, it is preferable to use the tenter type simultaneous biaxial stretching method or the Lisim simultaneous biaxial stretching method.

A preferred embodiment of the in-line coating method in the case of sequential biaxial stretching includes a method including the following steps. After the sheet molding step of molding the polyamide resin into a sheet to obtain an unstretched sheet, the unstretched sheet is stretched at a stretching temperature of 40 to 80 ° C (preferably 50 to 65 ° C) and 2.5 in the flow direction of the sheet. It is stretched to 3.5 times (MD stretch), and then a water-based coating liquid is applied to the uniaxially stretched polyamide film. The uniaxially stretched film coated with the water-based coating liquid also serves as a drying step, and is 2.5 to 3.5 times in the width direction under the conditions of preheating and stretching temperature of 50 to 220 ° C. (preferably 60 to 130 ° C.). The film of the present invention can be produced by a stretching step of stretching (TD stretching). When sequentially biaxially stretching, it is preferable to use both the roll stretching method and the tenter stretching method in combination. More specifically, MD stretching can be carried out by a roll stretching method, and TD stretching can be carried out by a tenter-type stretching method, whereby sequential biaxial stretching can be preferably carried out.

Other Steps The method of laminating each layer is not particularly limited, and for example, a) a method of forming a coating film with a coating liquid, b) a method of laminating a preformed film, c) a PVD method, a CVD method, etc. Any method of forming a vapor-deposited film can be adopted. Further, in the case of b), any of a method of laminating via an adhesive, a method of laminating by simultaneous extrusion molding, and the like can be adopted. In particular, when the film of the present invention is used as an exterior material of a battery such as a lithium ion secondary battery, a known method for producing the exterior material can also be adopted. In this case, it is also possible to laminate using a known adhesive.

For example, when laminating with a barrier layer, a two-component type of a laminate containing a urethane resin layer / polyamide film or a laminate containing a urethane resin layer / polyamide film / urethane resin layer and a metal foil for forming a barrier layer is used. It is possible to adopt a method such as dry laminating or thermal laminating via a urethane-based adhesive or the like.

Further, as a method for joining the barrier layer and the heat-sealing layer, a known method (dry laminating, heat laminating, extruded laminating, sandwich laminating method, etc.) can be used.

On the surfaces of the polyamide film, barrier layer, and heat-sealing layer on which the adhesive layer is formed, an anchor coat layer, a primer layer, a printing layer, and a clear layer are required as long as the effects of the present invention are not impaired. Etc. may be provided.

3. 3. Use of Polyamide-based Laminated Film The film (or laminate) of the present invention can be used for various purposes, but can be particularly preferably used as a packaging material. That is, it can be used as a packaging material for packaging the contents. The contents are not limited, and for example, contents such as foods and drinks, electronic parts, chemical products, cosmetics, and medical products (medical devices) can be packaged.

The form when used as a packaging material is not particularly limited, and can be used, for example, as a packaging bag or a packaging container. As the packaging bag, for example, it can be used as various bag bodies such as a pillow bag, a gusset bag, and a stand bag. The method of molding the bag may also be carried out according to a known method.

Furthermore, the present invention also includes a product (packaging product) in which the contents are packaged by the above-mentioned packaging material or packaging bag. Examples of the packaging state in this case include a state in which the contents are sealed from the outside by a packaging material or a packaging bag.

Examples and comparative examples are shown below, and the features of the present invention will be described more specifically. However, the scope of the present invention is not limited to the examples. In addition, "%" regarding weight or concentration described below indicates "mass%".

1. 1. Materials used (1) Polyurethane resin As the polyurethane resin, the following polyurethane aqueous dispersions (a) to (d) were used.
(A) Product name "Hydran AP40F" (manufactured by DIC Corporation, glass transition temperature 55 ° C., solid content concentration 25%)
(B) Product name "Takelac W-5030" (manufactured by Mitsui Chemicals, glass transition temperature 85 ° C, solid content concentration 30%)
(C) Product name "Takelac WS-4022" (manufactured by Mitsui Chemicals, glass transition temperature 115 ° C., solid content concentration 30%)
(D) Product name "Hydran AP-201" (manufactured by DIC Corporation, glass transition temperature 7 ° C., solid content concentration 25%)

(2) Organic Lubricants As the organic lubricants, the following (a) to (g) were used. Both are in the form of dispersions.
(A) Product name "AQUACER517" (manufactured by BYK, polyethylene wax, solid content concentration 35%, particle size 0.150 μm, melting point 120 ° C.)
(B) Product name "Hi-Tech E6400" (manufactured by Toho Chemical Industry Co., Ltd., polyethylene wax, solid content concentration 35%, particle size 0.050 μm, melting point 120 ° C.)
(C) Product name "Charine EE-370" (manufactured by Nissin Chemical Industry Co., Ltd., silicon-acrylic copolymer, solid content concentration 50%, particle size 0.450 μm)
(D) Product name "Cymac US-450" (manufactured by Toagosei Co., Ltd., silicon-acrylic copolymer, solid content concentration 30%, particle size 0.350 μm)
(E) Product name "Charine E RU-911" (manufactured by Nissin Chemical Industry Co., Ltd., silicon-urethane copolymer, solid content concentration 40%, particle size 0.330 μm)
(F) Product name "Alflow H-50ES" (manufactured by NOF CORPORATION, fatty acid amide, solid content concentration 42%, particle size 0.450 μm, melting point 113 ° C., 147 ° C.)
(G) Product name "Slipax E SA-20" (manufactured by Mitsubishi Chemical Corporation, fatty acid amide, solid content concentration 22%, particle size 0.460 μm, melting point 113 ° C., 147 ° C.)

(3) Other Additives The following (a) to (b) were used as other additives.
(A) Product name "Aerosil 200" (manufactured by Nippon Aerosil, silica particles, primary particle diameter 12 nm)
(B) Product name "MX100W" (manufactured by Nippon Shokubai Co., Ltd., acrylic particles, average particle diameter 150 nm)

2. Examples and Comparative Examples Example 1
(1) Preparation of coating liquid Water-based coating is performed by mixing the polyurethane aqueous dispersion "Hydran AP40F" and the organic lubricant "AQUACER515" in this order with water so that the solid content concentration becomes 9% by mass, and stirring the mixture. Liquid A was obtained. The "Hydran AP40F" and "AQUACER515" were weighed so that the solid content mass ratio was Hydran AP40F / AQUACER515 = 100/20.
(2) Manufacture of polyamide-based laminated film (sequential biaxial stretching)
Using an extruder equipped with a T-die, nylon 6 (manufactured by Unitika Ltd., A1030BRF, relative viscosity 3.1) is extruded into a sheet from the T-die and brought into close contact with a casting roll adjusted to a surface temperature of 18 ° C. It was rapidly cooled to obtain an unstretched sheet.
Next, the unstretched sheet was passed through a stretching roll heated to a preheating temperature of 58 ° C. and a stretching temperature of 61 ° C., and stretched in the MD direction so as to have a stretching ratio of 2.85 times to obtain an MD stretched film. .. Subsequently, a water-based coating liquid A having a solid content concentration of 9% by mass was applied to an MD stretched film so that the thickness after drying and stretching was 0.10 μm, and then TD under the conditions of a preheating temperature of 80 ° C. and a stretching temperature of 120 ° C. It was stretched in the direction at a stretching ratio of 3.20 times. Further, after heat treatment was performed under the conditions of a heat treatment temperature of 210 ° C. and a heat treatment time of 3 seconds, a relaxation treatment of 3% was performed in the TD direction.
The surface of the polyamide film of the obtained laminated film was subjected to corona treatment to obtain a polyamide-based laminated film (thickness 15 μm) in which a polyurethane resin layer having a thickness of 0.10 μm was laminated.
(3) Preparation of Laminated Body A two-component polyurethane adhesive (TM-K55 / CAT-10L, manufactured by Toyo Morton Co., Ltd.) was applied to the corona-treated surface of the obtained polyamide-based laminated film with a coating amount of 5 g / m ² . And dried at 80 ° C. for 10 seconds. An aluminum foil (thickness 50 μm) was attached to the adhesive-coated surface.
Next, the above adhesive was applied and dried on the aluminum foil surface under the same conditions, and an unstretched polypropylene film (manufactured by Mitsui Chemicals Tohcello Co., Ltd., GHC, thickness 50 μm) was attached as a heat-sealing layer under an atmosphere of 60 ° C. Aging treatment was carried out for 7 days to obtain a laminate in which "polyurethane resin layer / polyamide film / adhesive layer / aluminum foil / heat fusion layer" were laminated in this order.

Examples 2, 5 to 17 and Comparative Examples 1, 2, 4, 7
A polyamide-based laminated film was produced in the same manner as in Example 1 except that the conditions shown in Table 1 were used. The coating liquid was prepared in the same manner as in Example 1 except that the types and blending ratios of the polyurethane aqueous dispersion and the organic lubricant were changed as shown in Table 1. The order of addition of the organic lubricant in the coating liquid to which two kinds of organic lubricants are added is not limited and can be arbitrarily selected. Further, the obtained polyamide-based laminated film was used to prepare a laminated body in the same manner as in Example 1.

Example 3
A polyamide-based laminated film was produced in the same manner as in Example 1 except that the stretching method was changed as follows.
Using an extruder equipped with a T-die, nylon 6 (manufactured by Unitika Ltd., A1030BRF, relative viscosity 3.1) is extruded into a sheet from the T-die and brought into close contact with a casting roll adjusted to a surface temperature of 18 ° C. It was rapidly cooled to obtain an unstretched sheet.
Next, a water-based coating liquid B having a solid content concentration of 9% by mass was applied to this unstretched sheet using a gravure coater so that the thickness after drying and stretching was 0.10 μm, dried by a hot air dryer, and then pantographed. The method was guided to a tenter simultaneous biaxial stretching machine, and simultaneous biaxial stretching was performed at a stretching ratio of 3.0 times in the MD direction and 3.3 times in the TD direction under the condition of a preheating stretching temperature of 200 ° C. Further, the heat treatment was performed under the conditions of a heat treatment temperature of 215 ° C. and a heat treatment time of 3 seconds, and then a relaxation treatment of 3% was performed in the TD direction.
The surface of the polyamide film of the obtained laminated film was subjected to corona treatment to obtain a polyamide-based laminated film having a thickness of 15 μm in which a polyurethane resin layer having a thickness of 0.10 μm was laminated. Further, the obtained polyamide-based laminated film was used to prepare a laminated body in the same manner as in Example 1.

Example 4
A polyamide-based laminated film was obtained in the same manner as in Example 3 except that the simultaneous biaxial stretching machine was changed from a pantograph type tenter to a linear motor type tenter and a relaxation treatment of 1% was also applied in the MD direction. Further, the obtained polyamide-based laminated film was used to prepare a laminated body in the same manner as in Example 1.

Comparative Example 3
A polyamide-based laminated film was produced in the same manner as in Example 1 except that silica was contained in the aqueous coating liquid in an amount of 2.0% by mass based on 100% by mass of the solid content of the polyurethane aqueous dispersion. Further, the obtained polyamide-based laminated film was used to prepare a laminated body in the same manner as in Example 1.

Comparative Example 5
A polyamide-based laminated film was obtained in the same manner as in Example 1 except that the coating step of the water-based coating liquid was changed from during the stretching step to after stretching. In the coating process, the stretched polyamide film is guided to a gravure coater, a water-based coating liquid R is applied so that the coating thickness is 0.5 μm, and a drying furnace consisting of five zones <Zone 1 (80 ° C.) → Zone 2 ( A polyamide-based laminated film was obtained by passing through 100 ° C.) → Zone 3 (120 ° C.) → Zone 4 (110 ° C.) → Zone 5 (80 ° C.)> and drying. Further, the obtained polyamide-based laminated film was used to prepare a laminated body in the same manner as in Example 1.

Comparative Example 6
A polyamide-based laminated film was produced in the same manner as in Example 1 except that the aqueous coating liquid contained 2.0% by mass of acrylic particles with respect to 100% by mass of the solid content of the polyurethane aqueous dispersion. Further, the obtained polyamide-based laminated film was used to prepare a laminated body in the same manner as in Example 1.

Test Example 1
The following characteristics were measured for the polyamide-based laminated films or laminates obtained in each Example and Comparative Example. The results are shown in Table 2.

(1) Dynamic friction coefficient The dynamic friction coefficient of the surface of the polyurethane resin layer in the present invention was measured according to the Japanese Industrial Standard "JIS K7125". As the measuring device, a desktop material testing machine "STB-1225S" manufactured by A & D Co., Ltd. and a data processing system "TACT" were used, and the measuring environment was set to 23 ° C. × 50% RH and 20 ° C. × 90% RH. Specifically, after adjusting the humidity of a sample of the polyamide-based laminated film at 23 ° C. × 50% RH or 20 ° C. × 90% RH for 2 hours, the polyurethane resin layers of the polyamide-based laminated film are placed at the same temperature and humidity as described above. Was superimposed and the measurement was carried out. Even in the case of a laminate containing the film of the present invention as the outermost layer, the measurement was carried out in the same manner as described above, with the surface of the polyurethane resin layer as the outermost layer as the measurement surface. Practically, the coefficient of dynamic friction is required to be 0.30 or less at 23 ° C. × 50% RH and 0.40 or less at 20 ° C. × 90% RH. The measurement was carried out at n = 5, and the average value was used as the measured value.

(2) Arithmetic mean height (Ra)
The arithmetic mean height measurement (Ra) in the present invention conformed to the Japanese Industrial Standards "JIS B 0601" using the contact type surface roughness measuring machine "Surfcorder SE500A" of Kosaka Laboratory Co., Ltd. Specifically, after adjusting the humidity of a sample of the polyamide-based laminated film at 23 ° C. × 50% RH for 2 hours, the surface of the polyurethane resin layer was measured under the same temperature and humidity as described above. In the case of a laminate containing the film of the present invention as the outermost layer, the surface of the polyurethane resin layer as the outermost layer was used as the measurement surface. The measurement was carried out at n = 5, and the average value was used as the measured value.

(3) Contact angle The contact angle was measured using water with an automatic contact angle meter manufactured by KRUSS, model DSA30S. Specifically, a sample of the polyamide-based laminated film was humidity-controlled at 23 ° C. × 50% RH for 2 hours, and then measurements were carried out under the same temperature and humidity as described above. The measurement was carried out at n = 5, and the average value was used as the measured value.

(4) Printability (ink transferability from plate)
The printability in the present invention was measured under the same temperature and humidity conditions after adjusting the humidity of a sample of a polyamide-based laminated film at 23 ° C. × 50% RH for 2 hours. The polyurethane resin layer of the polyamide-based laminated film is printed using a gravure printing method so that the number of dot patterns within 1 cm x 1 cm is 100, and the number of defects of the dot patterns within 1 cm x 1 cm is counted, and the average value of the three locations is counted. Was calculated to evaluate printability. As the ink, a commercially available ink (Rio Alpha R39 Indigo, manufactured by Toyo Ink Co., Ltd.) was used. Regarding printability, practically, the number of defects of the dot pattern is preferably 7.0 or less, more preferably 3.5 or less, and most preferably 1.0 or less. ..

(5) Formability of laminated body (Eriksen test)
Based on the Japanese Industrial Standards "JIS Z 2247", a sample of the laminate prepared by using an Eriksen testing machine (No. 5755 manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at 23 ° C. x 50% RH for 2 hours was sampled at the same temperature and temperature as above. The measurement was carried out under humidity. A steel ball punch was pressed against the polyurethane resin layer surface of the sample of the laminated body at a predetermined pushing depth to obtain an Eriksen value, and the moldability was evaluated according to the following evaluation criteria. The Eriksen value was measured every 0.5 mm. Practically, the Eriksen value is preferably 5.0 mm or more, more preferably 8.0 mm or more, and most preferably 9.0 mm or more. The measurement was carried out at n = 5, and the average value was used as the measured value.

As is clear from the results in Table 2, the polyamide-based laminated film of each example has a small coefficient of dynamic friction on the surface of the polyurethane resin layer under a 20 ° C. × 90% RH environment, and has good printability and moldability. You can see that.
In the polyamide-based laminated films described in Comparative Examples 1 to 3, the glass transition temperature of the polyurethane aqueous dispersion was less than 50 ° C., so that the coefficient of kinetic friction on the surface of the polyurethane resin layer was large. Further, since the polyamide-based laminated film described in Comparative Example 4 did not contain an organic lubricant, Comparative Example 5 adopted a post-coating method, so that sufficient slipperiness could not be obtained. In Comparative Example 6, the coefficient of dynamic friction on the surface of the polyurethane resin layer was small due to the addition of acrylic particles, but the arithmetic mean height Ra exceeded the range specified in the present invention, and the printability and moldability were inferior. In Comparative Example 7, although the glass transition temperature was 50 ° C. or higher, the coefficient of kinetic friction on the surface of the polyurethane resin layer was high because no organic lubricant was added.

Claims (9)

1. A laminated film containing a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant laminated on at least one surface of the film.
   (1) The glass transition temperature of the polyurethane resin is 50 ° C. or higher.
   (2) The arithmetic mean height (Ra) of the surface of the polyurethane resin layer is 0.010 to 0.060 μm, and the coefficient of dynamic friction of the surface of the polyurethane resin layer under a 20 ° C. × 90% RH environment is 0. 40 or less,
   A polyamide-based laminated film characterized by this.
2. The polyamide-based laminated film according to claim 1, wherein the dynamic friction coefficient of the surface of the polyurethane resin layer under a 23 ° C. × 50% RH environment is 0.30 or less.
3. The polyamide-based laminated film according to claim 1, wherein the polyurethane resin layer has a thickness of 0.005 to 0.150 μm.
4. A laminate for food packaging containing the polyamide-based laminate according to any one of claims 1 to 3.
5. A laminate for cold molding containing the polyamide-based laminate film according to any one of claims 1 to 3.
6. A method for producing a polyamide-based laminated film containing a polyamide film and a polyurethane resin layer containing a polyurethane resin and an organic lubricant on at least one surface of the film.
   (1) A sheet molding step of obtaining an unstretched sheet by molding a melt-kneaded product containing a polyamide resin into a sheet.
   (2) A stretching step of obtaining a biaxially stretched film by MD stretching and TD stretching of the unstretched sheet, and (3) any one of the unstretched sheet, MD stretched film, TD stretched film or biaxially stretched film. A method for producing a polyamide-based laminated film, which comprises a coating step of applying a water-based coating liquid containing a polyurethane resin and an organic lubricant on one surface.
7. The production method according to claim 6, wherein the water-based coating liquid is a mixed liquid of a dispersion liquid of a polyurethane resin and a dispersion liquid of an organic lubricant having a particle size of 0.010 μm to 0.500 μm.
8. The stretching step is carried out by simultaneous biaxial stretching, and the following formulas (a) and (b);
   (A) 0.80 ≦ X / Y ≦ 0.95
   (B) 9.8 ≤ X x Y ≤ 11.6
   (However, X indicates the stretching ratio in the MD direction, and Y indicates the stretching ratio in the TD direction.)
   The manufacturing method according to claim 6, wherein both of the above are satisfied.
9. The stretching step is carried out by sequential biaxial stretching, and the following formulas (a) and (b);
   (A) 0.85 ≤ X / Y ≤ 0.95
   (B) 8.5 ≤ X x Y ≤ 9.5
   (However, X indicates the stretching ratio in the MD direction, and Y indicates the stretching ratio in the TD direction.)
   The manufacturing method according to claim 6, wherein both of the above are satisfied.

Images