JP6222906B2 - Biaxially stretched nylon film for cold forming - Google Patents

Description

The present invention relates to a cold forming biaxially stretched nylon film that is suitably used as a main base material for a cold forming packaging material, particularly a packaging material for a battery case such as a lithium ion secondary battery.

Conventionally, for example, chemical energy of lithium ion batteries, lithium ion polymer batteries, fuel cells, etc., or liquid capacitors including dielectric materials such as liquids, solid ceramics, and organic substances, solid capacitors, electrolytic capacitors such as double layer capacitors, etc. Various batteries including elements that convert to electric energy are widely used in personal computers, portable terminal devices (cell phones, PDAs, etc.), video cameras, electric vehicles, energy storage batteries, robots, satellites, and the like. As these battery outer bodies, metal cans formed by pressing metal into cylinders or rectangular parallelepiped containers, or laminates obtained by laminating plastic films, metal foils, etc. in the form of bags (Hereafter, exterior body) was used.

However, among the battery outer bodies, in the metal can type, since the outer wall of the container is rigid, it is necessary to design the hardware side according to the shape of the battery, and there is a problem that the degree of freedom of the shape is lost. . In addition, since the metal can type is thick, there is a drawback that it is difficult to dissipate heat when the battery generates heat, such as when used for a long time. On the other hand, the laminate type is easy to take out the metal terminal, easy to seal, or flexible, so it can be shaped to fit the appropriate space of the electronic device or electronic component. The shape of itself can be designed freely to some extent. Furthermore, since the thin film is excellent in heat dissipation, it is possible to prevent abnormal discharge due to heat generation. Therefore, the laminated body type is becoming mainstream as a battery exterior body because of advantages such as a reduction in size and weight, and high safety compared to a metal can type.

As a form of a lithium battery using a laminate type exterior body, a packaging material is processed into a cylindrical shape, and a metal terminal connected to each of the lithium battery main body and the positive electrode and the negative electrode is stored in a state of protruding outward. A bag type (for example, see FIG. 2 of Patent Document 1) in which the opening is thermally bonded and sealed, and a packaging material are formed into a container shape, and are connected to the lithium battery body, the positive electrode, and the negative electrode in the container. The metal terminal is housed in a state of protruding outward, covered with a flat packaging material or a packaging material molded into a container, and the four peripheral edges are thermally bonded and sealed (for example, FIG. 3) is known.

And since the molded type can store the battery body tightly (tight state) compared to the bag type, the volume energy density can be improved and the lithium battery body can be easily stored. There are advantages. Furthermore, among the molding types, the cold (room temperature) molding method has a lower risk of changes in the properties of the packaging material during molding, such as a decrease in strength properties due to heating and the occurrence of thermal shrinkage, compared to the heat molding method. Furthermore, since the molding apparatus is inexpensive, simple and highly productive, it is currently the mainstream molding method.

The physical properties and functions required for battery exteriors include advanced moisture resistance, sealing, piercing resistance, pinhole resistance, insulation, heat / cold resistance, electrolyte resistance (electrolyte resistance), Corrosion properties (resistance to hydrofluoric acid generated by electrolyte degradation and hydrolysis) are essential, and moisture resistance is an important factor. However, in the laminate type, especially the cold forming type, the aluminum foil generally used as a metal foil is excellent in formability, but there is a problem that pinholes and cracks are likely to occur due to non-uniform deformation that occurs during forming. There is room for improvement in terms of molding stability, which is deep and stable molding with a simple shape. In addition, the laminate type is composed of at least a base material layer, a barrier layer, and a sealant layer, but it has been confirmed that the adhesive strength between the respective layers affects the properties required for the battery outer package. . For example, if the adhesive strength between the barrier layer and the base material layer is insufficient, the heat shrink stress of the base material layer when the battery body is stored and sealed by heat sealing or when used for a long time at a high temperature. However, there is a problem that delamination (peeling) occurs between the barrier layer and the base material layer. In particular, the occurrence of delamination was high during heat sealing in which heat of around 200 ° C. was applied to the base material layer. When delamination occurs between the barrier layer and the base material layer, it may cause deterioration of strength characteristics such as piercing resistance and pinhole resistance among the required characteristics of the battery exterior body, which may cause water vapor to enter from the outside. . When water vapor enters the inside, there is a problem that the aluminum foil as the barrier layer is corroded by hydrofluoric acid generated by reacting with an electrolyte which is one of the components forming the battery.

As described above, various proposals have been made so far regarding the main quality problems of the battery-type outer casing of the laminate type, particularly the cold-forming type, that is, ensuring excellent cold-formability and suppressing delamination between the respective layers. Yes. As a method for ensuring excellent cold formability, for example, Patent Document 2 coats a base material layer surface with a fatty acid amide-based slipperiness-imparting component to improve slipping into a mold during molding. Methods for improvement, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6 pay attention to the strength properties of the base material layer such as nylon film, and are different in order to suppress breakage of the aluminum foil during cold forming. A method of reinforcing an aluminum foil by using a base material having a low property and having a property such as high strength or high elongation, and further, a method focusing on the crystallinity of the base material layer as in Patent Document 7 Proposed. On the other hand, as a method for suppressing delamination, Patent Literature 8 proposes a method for limiting the hot water shrinkage of the base material layer, and Patent Literature 9 proposes a method for limiting the density of the base material layer to a certain range.

However, the method of coating the surface of the base material layer with a slipperiness-imparting component has a problem in that productivity must be reduced because a coating step must be provided. In addition, the slipperiness-imparting component evaporates when the battery is vacuum degassed or sealed, and the evaporated component adheres to the processing equipment, which necessitates a cleaning operation to remove them, further reducing productivity. There was a problem to do. In addition, the method of reinforcing an aluminum foil using a high-strength or high-strength base material has no improvement on the suppression of delamination, although the moldability is improved. Furthermore, the method of limiting the hot water shrinkage rate of the base material layer and suppressing delamination is particularly suitable for the heat sealing process in which heat of around 200 ° C., which is frequently generated, is applied to the base material, and for delamination under conditions of high temperature and high humidity. The conditions did not necessarily match the occurrence status, and it was insufficient as an indicator for delamination. In addition, delamination occurs when the thermal shrinkage stress of the base material layer is greater than the interlayer adhesive strength, so delamination can be completely suppressed simply by limiting the amount of shrinkage in hot water. It was not always possible to do.

In view of the above problems, the authors limit the thermal shrinkage stress and tensile strength of the nylon film, which is the base material layer of Patent Document 10, to a certain range, thereby providing a laminate type, particularly a cold-molded type battery outer package. It was found that it was possible to achieve both excellent cold formability, which was the main quality issue, and suppression of delamination between layers. However, secondary batteries represented by lithium ion batteries are widely used. Recently, they are used for relatively long and harsh conditions such as those for automobiles, and the demand for durability is increasing for exterior materials. ing. With conventional technology, durability under severe conditions, especially when high temperature and high humidity, or when a printing layer is provided between ONy film and aluminum foil, the adhesive strength between each layer may be weakened, and there is a risk of delamination. There was also a case where it increased.

On the other hand, an easy-adhesive nylon film has been developed for the purpose of requiring adhesiveness at the time of boiling and retorting for the purpose of improving the laminate strength. (Patent Documents 11, 12, and 13) However, there is no example in which this is applied as a base material for battery outer packaging materials.

JP 2004-74419 A JP 2002-216714 A JP 2000-123800 A JP 2006-236938 A JP 2008-44209 A JP 2005-22336 A JP 2007-42469 A JP 2006-331897 A JP 2008-288117 A JP 2011-162702 A Japanese Patent Publication No.57-26236 JP-A-8-258232 JP 11-20104 A

The present invention provides a nylon film for cold forming that does not cause delamination even when it is provided with a durability under severe conditions as described above, in particular, at high temperatures and high humidity, or when a printing layer is provided between ONy and aluminum foil. It is a problem to obtain.

As a result of intensive research on this subject, the present inventor has found that the surface of a biaxially stretched film having a specific strength property is thinly coated with a specific resin, and for a battery using this as a base material. We have found that it is possible to achieve both excellent cold formability as an exterior material and suppression of delamination between layers under severe conditions such as high temperature and high humidity and the presence of a printed layer.

In particular,
[1] An easy-adhesive nylon film characterized in that an unstretched or stretched nylon film that has not been heat-treated is coated with a polyurethane resin or an acrylic acid copolymer resin and a crosslinking agent thereof, and then heat-treated. The maximum value of the heat shrinkage stress at 170 to 210 ° C. is 5.0 MPa or less for both MD and TD, and four directions (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.) ( (0 ° (MD), 45 °, 90 ° (TD), 135 °) Biaxially stretched nylon film characterized by having a breaking strength of 240 MPa or more,
[2], Aqueous coating comprising, as a main component, a resin A and a crosslinking agent B according to [1], which are A and B below, and a composition comprising a solid content weight ratio A / B = 98 to 30/2 to 70 The biaxially stretched nylon film according to [1], wherein the coating amount after stretching the working agent is 0.005 to 0.030 g / m ² in solid content,
A: An aqueous polyurethane resin containing a nonionic surfactant which is an acetylene glycol in which a hydroxyl group and a methyl group are substituted on two adjacent carbon atoms of a triple bond and / or its ethylene oxide adduct.
B: Water-soluble polyepoxy compound.
[3] In the coating agent according to [2], fine particles C having an average particle size of 0.001 to 1.0 μm are in a solid content weight ratio A / B / C = 98 to 30/2 to 70 / 0.1. The biaxially stretched nylon film according to [2], wherein the biaxially stretched nylon film is included so as to be 10;
[4] 50% of all four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) in a uniaxial tensile test (sample width: 15 mm, distance between chucks: 100 mm, tensile speed: 200 mm / min.) The biaxially stretched nylon film according to any one of [1] to [3], wherein a modulus value is 120 MPa or more,
[5] A battery case packaging material for cold forming formed of at least a base material layer, a barrier layer, and a sealant layer, and the biaxially stretched nylon according to [1] to [4] as the base material layer Battery case packaging material for cold forming, characterized in that the coated surface of the film is arranged on the barrier layer side,
[6] A battery case packaging material for cold forming formed of at least a base material layer, a barrier layer, and a sealant layer, and the biaxially stretched nylon according to [1] to [4] as the base material layer Battery case packaging material for cold forming, characterized in that printing is performed on the coated surface of the film, and the printed surface is disposed on the barrier layer side,
A battery case using the cold-forming battery case packaging material according to [7], [5] or [6], and forming a concave portion by overhang molding or deep drawing so that the sealant layer is on the inner surface. ,
[8] A battery characterized in that the battery body is housed in a recessed portion of the battery case according to [7] and sealed.
I will provide a.
Here, one of the preferred embodiments of the biaxially stretched nylon film of the present invention is:
An unstretched or unstretched nylon film that has not been heat-treated, coated with a polyurethane resin, a cross-linking agent and an aqueous coating agent mainly composed of fine particles, and then heat-treated, an easily-adhesive nylon film,
When the easy-adhesive nylon film is used as a base material layer, it is possible to suppress the occurrence of delamination between the base material layer and the aluminum foil layer under high temperature and high humidity and is excellent in moldability.
The maximum value of heat shrinkage stress at 170 to 210 ° C. is 5.0 MPa or less for both MD and TD, and the four directions (0 ° (0 ° (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.)). MD), 45 °, 90 ° (TD), 135 °) all breaking strengths are 280 MPa or more and 50% modulus value is 150 MPa or more,
The polyurethane resin, the crosslinking agent and the fine particles thereof in the aqueous coating agent are the following A, B and C, respectively, and the solid content weight ratio A / B / C = 98 to 30/2 to 70 / 0.1 A biaxially stretched nylon film, characterized in that the coating amount of the aqueous coating agent is 10 to 0.050 g / m ² in terms of dry weight after stretching.
A: Aqueous polyurethane resin containing acetylene glycol in which hydroxyl groups and methyl groups are substituted on two adjacent carbon atoms of a triple bond and / or a nonionic surfactant that is an ethylene oxide adduct thereof
B: Water-soluble polyepoxy compound
C: Fine particles having an average particle size of 0.001 to 1.0 μm
It is.
One of the preferred embodiments of the cold-forming battery case packaging material of the present invention is:
Constructed by laminating at least a base material layer, a barrier layer and a sealant layer in this order, it is possible to suppress the occurrence of delamination between the base material layer and the barrier layer under high temperature and high humidity and formability A battery case packaging material for cold forming, excellent in
An easily-adhesive nylon film that has been heat-treated after coating a polyurethane resin, a cross-linking agent and an aqueous coating agent mainly composed of fine particles on a non-stretched or unheated nylon film with the base material layer unstretched or stretched. The maximum value of heat shrinkage stress at 170 to 210 ° C. is 5.0 MPa or less for both MD and TD, and the four directions in the uniaxial tensile test (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.). (0 ° (MD), 45 °, 90 ° (TD), 135 °) All the breaking strengths are 280 MPa or more and the 50% modulus value is 150 MPa,
The polyurethane resin, the crosslinking agent and the fine particles thereof in the aqueous coating agent are the following A, B and C, respectively, and the solid content weight ratio A / B / C = 98 to 30/2 to 70 / 0.1 A biaxially stretched nylon film in which the coating amount of the aqueous coating agent is 0.010 to 0.050 g / m ² in terms of dry weight after stretching,
A battery case packaging material, wherein the barrier layer is an aluminum foil layer.
A: Aqueous polyurethane resin containing acetylene glycol in which hydroxyl groups and methyl groups are substituted on two adjacent carbon atoms of a triple bond and / or a nonionic surfactant that is an ethylene oxide adduct thereof
B: Water-soluble polyepoxy compound
C: Fine particles having an average particle size of 0.001 to 1.0 μm
It is.

The present invention relates to a biaxially stretched nylon film for cold forming, wherein a specific resin is thinly applied to at least one surface, the anisotropy is small, and the tensile strength is high. In particular, when used as a main base material for battery case packaging materials such as lithium ion secondary batteries, when it is used for a long time in the process of heat sealing and sealing, under high temperature and high humidity, or with a printed layer interposed However, it is possible to suppress the occurrence of delamination between the barrier layer and the base material layer, and there is no occurrence of aluminum foil breakage or pinholes during cold forming of any mold shape and molding depth. As a result, stable moldability can be secured. In addition, as in the prior art, excellent moldability can be secured without coating with a slipperiness-imparting component, so that productivity is also excellent.

The process drawing of the in-line resin coating tubular drawing apparatus which manufactures an ONy film.

The best mode for carrying out the present invention will be described below.
(Raw Material of Biaxially Stretched Nylon Film) The raw material of the biaxially stretched nylon film (hereinafter referred to as ONy film) of the present invention is not particularly limited as long as it is a polyamide resin. For example, nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6, 66, 12 copolymer, other polyamide copolymers, nylon MXD6, aramid, polyamideimide (PAI), aromatic Polyimide, polyetherimide (PEI), polymaleimidoamine (PMIA), polyaminobismaleimide (PABM), etc. are mentioned. Nylon 6 is used from the viewpoint of film physical properties such as productivity, cold formability and strength properties. Most preferred. In the nylon 6 raw material, the number average molecular weight is preferably 10,000 to 30,000, particularly preferably 22,000 to 24,000. When the number average molecular weight is less than 10,000, the impact strength and tensile strength of the obtained ONy film are insufficient. When the number average molecular weight is larger than 30000, the molecular chain is entangled excessively and excessive strain is generated by the stretching process. Therefore, breakage and puncture frequently occur during the stretching process, and stable production cannot be achieved.

(Raw material of coating agent)
The coating agent used in the present invention needs to have a polyurethane resin or an acrylic acid copolymer resin as a main component and be crosslinked with a crosslinking agent. A preferable resin is a water-based emulsion, and a cross-linking agent is preferably a water-soluble cross-linking agent from the viewpoint of easy coating and environmental friendliness. Examples of resins are shown below, but they can be coated with a polyurethane resin or acrylic resin, and the cohesive strength of the resin itself with respect to water and solvents is extremely low due to the crosslinking structure with an appropriate crosslinking agent. Can be used without particular attention.

The water-based polyurethane resin is preferably a self-emulsifying type from the viewpoint of small particle size and good stability. The particle diameter is preferably about 10 to 100 nm. The water-based polyurethane resin used in the present invention preferably has a glass transition point (Tg) of 40 ° C to 150 ° C. When the Tg is less than 40 ° C., blocking occurs when winding into a roll after coating, leaving a trace of adhesion, resulting in transparent spots, and if it is more severe, the film cannot be rewound. Moreover, since this invention is in-line coating which extends after coating on a polyamide film, if the Tg is too higher than the drying temperature after coating and the temperature applied during stretching, it is difficult to form a uniform coating film. This is because the minimum film forming temperature (MFT) for forming a continuous coating film is generally in the vicinity of Tg, and is preferably less than 150 ° C.

In the present invention, the water-based polyurethane resin is added with acetylene glycol in which a hydroxyl group and a methyl group are substituted on two adjacent carbon atoms of a triple bond and / or a nonionic surfactant that is an ethylene oxide adduct thereof. It is preferable. Examples of such surfactants include Surfinol 104, 440 manufactured by Nissin Chemical Industry Co., Ltd. The addition amount is preferably 0.01 to 1.0% with respect to the solid content of the water-based polyurethane resin. Conventionally, two types of surfactants (antifoaming agent and wetting agent) are generally used to solve the difficulty of uniform “wetting” on films due to foaming and large surface tension of water when using coating agents. I had to add it. In many cases, the defoaming effect and the wetting effect are contradictory, so if one is solved, the other is worsened. By adding this surfactant, wetting to the film is improved, and even if the coating amount is small, a uniform coating film can be obtained. Troubles caused by foaming during preparation of the coating agent and during coating are also eliminated.

As the water-based polyurethane crosslinking agent used in the present invention, general-purpose water-soluble crosslinking agents such as water-soluble epoxy compounds and water-soluble oxazoline compounds can be used, but water-soluble polyepoxy compounds are particularly preferred from the viewpoint of safety. A water-soluble epoxy compound is a compound having solubility in water and having two or more epoxy groups. For example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene Diepoxy compounds obtained by etherification of 1 mol of glycols such as glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 2 mol of epichlorohydrin, glycerin, polyglycerin, trimethylolpropane, pentaerythritol , Polyepoxy compounds obtained by etherification of 1 mol of polyhydric alcohols such as sorbitol and 2 mol or more of epichlorohydrin, terephthalic acid phthalate, Although diepoxy compound obtained by esterification of a dicarboxylic acid 1 mol of epichlorohydrin 2 moles, and the like are not limited to these, such as adipic acid. These water-soluble crosslinking agents crosslink with the water-based polyurethane resin, improve the water resistance and solvent resistance of the coating film, and further contribute to adhesion to the polyamide film.

Fine particles can be added to the coating agent in the present invention to improve processability during lamination. Due to the presence of fine particles in the coating film, the function of a blocking agent and a slipping agent that imparts an appropriate slipping property in post-processing steps such as winding, printing, laminating, and coating are developed. Fine particles having an average particle diameter of 0.001 to 1.0 μm are used, and preferably spherical fine particles are used. True spherical fine particles mean that the minor axis / major axis is 0.90 or more in the electron micrograph. It is preferable that the fine particles are spherical because the effect on blocking resistance and slipping is excellent and the decrease in transparency is small. On the other hand, when the average particle size is less than 0.001 μm, there is no effect on the blocking resistance and the slipping property. When the average particle diameter exceeds 1.0 μm, the printability is lowered. In particular, in the case of photographic printing, ink loss occurs at the highlight portion. The fine particles may be inorganic or organic, but they need heat resistance that is not deformed during the manufacturing process and loses its effect.

The fine particles are not particularly limited to inorganic or organic compounds, but preferred fine particles include, for example, colloidal silica “Snowtex” ST-C (average particle diameter: 0.010 to 0.020 μm), ST-XS, manufactured by Nissan Chemical Industries, Ltd. (Average particle diameter of 0.004 to 0.006 μm).
In the present invention, the weight ratio of the mixing ratio A / B of the water-based polyurethane resin (A) containing the surfactant and the water-soluble polyepoxy compound (B) is 98/2 to 30/70 in solid content. . When the ratio of A / B is larger than 98/2, the crosslinking density is decreased, and the water resistance, solvent resistance and adhesiveness are inferior. Conversely, if the A / B ratio is less than 30/70, blocking during aging remains as a problem. The blending amount of the fine particles (C) is such that the ratio of the total amount (A + B) of the water-based polyurethane resin (A) containing the surfactant and the water-soluble polyepoxy compound (B) is 0. 1/100 to 10/100. If this ratio is less than 0.1 / 100, the effect of blocking resistance and slipping properties is insufficient, and conversely, even if it is greater than 10/100, the effect is not changed and it is economically disadvantageous.

The coating amount of a water-based polyurethane resin fat containing a surfactant, a water-soluble polyepoxy compound and fine particles as a main component is 0.005 to 0.1000 g / m ^{2 in} terms of dry weight after stretching, preferably It is desirable that it is 0.010-0.050 g / m < ² >. If it is less than 0.005 g / m ² , a uniform coating film cannot be obtained and water resistance and adhesiveness are insufficient. Conversely, when 0.100 g / m ² or more is applied, the coated surface / non-coated surface is likely to be blocked. Moreover, the improvement in performance is not recognized and the cost increases, which is not preferable.

The acrylic acid copolymer resin preferably has a glass transition point of 40 ° C. or higher. Those with a glass transition point of less than 40 ° C. are wound with a water-soluble polyepoxy compound to be crosslinked and cured, and then rolled into a roll. When aging at 30 to 60 ° C., blocking occurs, leaving a trace of adhesion and transparent. If it becomes more uneven and more severe, it cannot be rewound, and if it is rewound forcibly, the film will break, which is not preferable. The acrylic resin used in the present invention is particularly preferably a main monomer composed of acrylic acid esters and / or methacrylic acid esters and the like, and a comonomer having an epoxy group and a functional group contributing to a crosslinking reaction. It can be obtained by copolymerizing a neutral monomer that can be copolymerized with the above monomer.

Among the main monomers, acrylic acid esters include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, acrylic acid 2 Ethylhexyl and the like, and methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, methacrylic acid 2 And ethylhexyl.
Examples of the comonomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, maleic acid monoester, fumaric acid monoester and other α, β-unsaturated carboxylic acids, and 2-hydroxyethyl methacrylate. , Hydroxy compounds such as polyethylene glycol monomethacrylate, epoxy compounds such as glycidyl methacrylate and allyl glycidyl ether, amines such as allylamine, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropylacrylamide, N-methylacrylamide Examples thereof include, but are not limited to, amides such as maleic acid anhydride, and acid anhydrides such as maleic anhydride. The functional group of these monomers contributes to crosslinking with a polyepoxy compound, adhesion to a plastic film, and the like.

Examples of the neutral monomer capable of copolymerization include styrenes such as styrene and α-methylstyrene, acrylonitriles such as acrylonitrile and methacrylonitrile, aliphatic vinyl esters such as vinyl acetate and vinyl propionate, and vinyl methyl ether. , Vinyl alkyl ethers such as vinyl ethyl ether, α-olefins such as ethylene, propylene, and 1-butene, vinyl chloride, vinylidene chloride, and the like, but are not limited thereto.

The acrylic acid copolymer resin and epoxy crosslinking agent used in the present invention are preferably water-soluble. The organic solvent solution has problems such as risk of flammable explosion, acute and chronic poisoning, and cost increase due to the use of an expensive organic solvent. In the present invention, it is preferable to use an aqueous coating agent. However, a minimum organic solvent necessary for imparting water solubility may be used.

When the above-mentioned copolymer is an aqueous dispersion, it is inferior in film-forming property as compared with an aqueous solution, and has problems in adhesion, water resistance, and solvent resistance. Is preferred. In this case, the aqueous dispersion to be used is preferably emulsified without using an emulsifier. In addition, a solution polymerized using a small amount of a water-soluble organic solvent can be used by making it water-soluble by adding an acid or base to the organic solvent solution, but the method of water-solubilization is not limited to these. Absent.

The molecular weight of the acrylic acid copolymer resin used in the present invention is preferably 5,000 or more and 100,000 or less. When the molecular weight is less than 5,000, water resistance, solvent resistance and scratch resistance are poor, and when the molecular weight exceeds 100,000, water-solubilization becomes difficult, and the viscosity increases and handling becomes difficult. The molecular weight here refers to the weight average molecular weight in terms of polymethyl methacrylate homopolymer by GPC (gel permeation chromatography).

The water-soluble polyepoxy compound used in the present invention is a compound having solubility in water and having two or more epoxy groups, such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, Diepoxy compounds obtained by etherification of 1 mol of glycols such as tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 2 mol of epichlorohydrin, glycerin, polyglycerin, tri Polyepoxy compounds obtained by etherification of 1 mol of polyhydric alcohols such as methylolpropane, pentaerythritol, sorbitol and 2 mol or more of epichlorohydrin, Phthalic acid, oxalic acid, diepoxy compounds obtained by esterification of a dicarboxylic acid 1 mol of epichlorohydrin 2 moles of adipic acid are exemplified, but the invention is not limited thereto. These polyepoxy compounds crosslink with the crosslinkable functional groups of the acrylic copolymer resin used in the present invention to improve the water resistance and solvent resistance of the coating film, and also contribute to the adhesion to the plastic film. To do.

(Method for producing resin-coated biaxially stretched nylon film)
The resin-coated biaxially stretched nylon film (hereinafter referred to as “ONy film”) of the present invention is formed by extruding a polyamide resin raw material from a die and forming a raw material, and then stretching and heat-fixing. It must be carried out on the stretched film before the raw fabric or heat treatment. The applied resin dramatically increases the cohesive force with the film by heat treatment, and can form a strong coating layer. The method of resin coating is not particularly limited as long as a predetermined thin film coating amount can be obtained. The coating before stretching is preferred from the viewpoint of ease of coating because the coating layer becomes thin in the subsequent stretching step. For example, if a solid content of 1 g / m ^{2 is} applied by gravure coating and then the MD and TD are stretched 3.2 times, the coating amount after the stretching is 0.1 g / m ² . The resin of the present invention may be applied to the stretched nylon film after stretching and before heat treatment.

With respect to the unstretched original fabric composed of any one of the polyamide-based raw materials, the draw ratio is preferably in the range of 2.8 to 4.0 times for MD and TD, particularly preferably 3.0. It is a range of ~ 3.4 times. When the draw ratio is less than 2.8 times, the impact strength and tensile strength of the obtained ONy film are insufficient. Further, when the ratio is 4.0 times or more, excessive molecular chain distortion occurs due to stretching, and thus breakage and puncture frequently occur during stretching and stable production cannot be achieved. Examples of the biaxial stretching method include simultaneous biaxial stretching by a tubular method or a tenter method, or sequential biaxial stretching, but simultaneous biaxial stretching by a tubular method is preferable from the viewpoint of longitudinal and lateral strength balance. By performing biaxial stretching in this manner, an ONy film having particularly improved strength properties and excellent cold formability can be obtained.

In general, since the polyamide film of the present invention is laminated with printing, metal deposition, or other films, the wetness index of the coating film surface is preferably 40 to 52 dyn / cm. Since the wetting index is increased by the resin coating of the present application, the surface treatment may not be performed by corona treatment after the coating film is formed.

The obtained resin-coated stretched film is subjected to heat treatment at 185 to 215 ° C., particularly preferably at 190 to 210 ° C., for any time in a heat roll system or a tenter system, or a heat treatment facility combining them. The ONy film of the invention can be obtained. When the heat treatment temperature is higher than 215 ° C., the bowing phenomenon becomes too great and the anisotropy in the width direction increases, or the crystallinity becomes too high, resulting in a decrease in strength properties. On the other hand, when the heat treatment temperature is lower than 185 ° C., the thermal dimensional stability of the film is greatly reduced, so that the film is easily shrunk at the time of lamination, or delamination is performed in a process of heat sealing and sealing after cold forming. Is likely to occur, causing a problem in practical use.

The thickness of the ONy film is preferably 5 to 50 μm, more preferably 10 to 30 μm. When the thickness is less than 5 μm, the impact resistance of the laminate packaging material becomes low, and the cold formability becomes insufficient. On the other hand, when the thickness exceeds 50 μm, the strength for maintaining the shape is improved, but the effect for preventing breakage and improving the moldability is small, and only the volume energy density is reduced.

The uniaxial tensile strength at break and the 50% modulus value in four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) of the ONy film are determined by a uniaxial tensile test (sample width: 15 mm, distance between gauge points: 50 mm). , From a stress-strain curve obtained by a tensile speed of 200 mm / min). In this stress-strain curve, the tensile breaking strength in the four directions is preferably 240 MPa or more, and more preferably 280 MPa or more. As a result, the ONy film and aluminum foil are difficult to break during cold forming even in the case of a mold shape with a large forming depth, which is generally considered difficult to form, ensuring stable and excellent formability. I can do it. If the tensile breaking strength is less than 240 MPa in any one of the four directions, the ONy film will be easily broken during cold forming, and the forming depth that requires high tensile strength at high elongation is particularly high. When molding a large mold shape, stable moldability cannot be obtained. Furthermore, in the stress-strain curve, the 50% modulus values in the four directions are all preferably 120 MPa or more, and more preferably 150 MPa or more. Thereby, stable moldability can be ensured particularly when a mold shape having a relatively small molding depth is molded. When the 50% modulus value is less than 120 MPa or more in any one of the four directions, the ONy film easily breaks during cold forming, and stable moldability cannot be obtained.

The maximum value of the heat shrinkage stress at 170 to 210 ° C. of the ONy film is preferably 5.0 MPa or less for both MD and TD, and can maintain stable quality even during secondary processing such as heat sealing after molding. . When the maximum value of heat shrinkage stress is greater than 5.0 MPa for either MD or TD, the heat shrinkage stress of the base material increases. When a printing layer is interposed between aluminum foils, delamination (peeling) easily occurs between the aluminum foil layer and the base material layer.

(Configuration of Laminate Packaging Material) The laminate packaging material is configured by laminating one or two or more other base materials on at least one surface of the above-described ONy film. Specifically, as other base materials, pure aluminum foil for imparting high moisture resistance or an aluminum foil layer made of a soft material of an aluminum-iron-based alloy, and polyethylene for imparting sealability and chemical resistance, Examples thereof include a heat seal layer made of an unstretched film such as polypropylene, maleic acid-modified polypropylene, maleic acid-modified polyethylene, ethylene-acrylate copolymer, ionomer resin, and polyvinyl chloride. In general, a laminate packaging material including an aluminum foil layer is not suitable for cold forming because the aluminum foil layer is easily broken or pinholes during cold forming. However, since the laminate packaging material including the ONy film of the present invention has excellent moldability, impact resistance and pinhole resistance, the aluminum layer breaks during cold stretch molding or deep drawing. Can be suppressed. Moreover, since it has excellent adhesiveness, it is possible to suppress the occurrence of delamination between the ONy film and the aluminum foil even when heat of about 200 ° C. is applied or under conditions of high temperature and high humidity. Furthermore, since the ONy film of the present invention is also excellent in adhesiveness with ink, there is no problem in quality even if a printing layer is provided between the ONy film and the aluminum foil layer as required.

The total thickness of the laminate base material including the ONy film is preferably 200 μm or less. When the thickness exceeds 200 μm, it becomes difficult to form the corner portion by cold forming, and a molded product having a sharp shape may not be obtained.

The thickness of the aluminum foil layer is preferably 20 to 100 μm. Thereby, it becomes possible to hold | maintain the shape of a molded article favorably, and it can prevent that oxygen, a water | moisture content, etc. penetrate | invade into a packaging material. When the thickness of the aluminum foil layer is less than 20 μm, the aluminum foil layer is likely to break during cold forming of the laminate packaging material, and pinholes and the like are likely to occur even when the laminate packaging is not broken. Or moisture may enter. On the other hand, when the thickness of the aluminum foil layer exceeds 100 μm, the effect of preventing breakage and pinhole generation during cold forming is not greatly improved, and only the total thickness is not preferable.

The laminate wrapping material including the ONy film of the present invention is a wrapping material having a performance that can be processed by a cold (room temperature) forming method such as stretch forming or deep drawing, although the total thickness of the wrapping material is thin. Because of its high strength, it is a laminate packaging material that can be sharply molded and that prevents the aluminum foil from being broken or pinholes during molding.

As a field where the laminate packaging material including the ONy film of the present invention is used, and as an application, particularly for a packaging material for a lithium secondary battery that uses a highly corrosive electrolytic solution and extremely hates invasion of moisture and oxygen. Although most suitable, other primary batteries and secondary batteries that require weight reduction and size reduction can also be used when the battery case is lightweight and requires sharp formability. . In addition to packaging materials for batteries, it has excellent heat sealability, chemical resistance, moldability, etc., so containers for materials containing pharmaceuticals, cosmetics, photographic chemicals, and other highly corrosive organic solvents It can also be used as a packaging material.

The present invention will be specifically described below with reference to examples and comparative examples.
Reference example 1
(Manufacturing method of coating agent)
Coating agent A: Self-emulsifying polyurethane resin “Takelac” W-6010 manufactured by Takeda Pharmaceutical Co., Ltd. and water-soluble polyepoxy compound “Denacol” EX-521 (polyglycerol polyglycidyl ether manufactured by Nagase Chemical Industries Co., Ltd.) ), “Surfinol 440” manufactured by Nissin Chemical Industry Co., Ltd., and colloidal silica “Snowtex” ST-C (average particle size 10-20 nm) manufactured by Nissan Chemical Industries, Ltd., 70/30 / 0.0. The mixture was added at a mixing ratio of 05/5 and diluted with water.
(Manufacture of biaxially stretched nylon film) After melt-kneading nylon 6 pellets (relative viscosity 3.48) at 255 ° C in an extruder, the melt was extruded as a cylindrical film from a die and then quenched with water. A raw film was prepared. Next, as shown in FIG. 1, after corona treatment is performed on both sides of the raw material in advance to increase the wetting index, the coating agent A is coated on both sides with a solid content of 0.3 g / m ² by an offset gravure coat and dried. did. The raw film is inserted between a pair of low-speed nip rolls 1 and then heated by the heater 2 and the heater 3 while air is being pressed into the film. MD and TD simultaneous biaxially stretched films 5 by the method were obtained. The draw ratio was 3.0 times for MD and 3.2 times for TD. Next, the stretched film 5 is put into a heat roll type and a tenter type heat treatment facility, respectively, heat treated at 210 ° C., trimmed at both ends, and then opened into two sheets to obtain an ONy film coated with resin on one side. It was. The ONy film had a thickness of 25 μm and a resin coating amount of 0.03 g / m ² .

(Uniaxial tensile breaking strength of ONy film, evaluation method of 50% modulus value) For the evaluation method of uniaxial tensile breaking strength of ONy film and 50% modulus value, Tensylon (RTC-1210-A) manufactured by Orientec was used. The test was carried out at a width of 15 mm, a gap between chucks of 100 mm, and a tensile speed of 200 mm / min. The ONy film 18 was measured in four directions of 0 ° C. (MD) direction / 45 ° direction / 90 ° (TD) direction / 135 ° direction after humidity conditioning for 2 hours in an environment of 23 ° C. × 50%. . Based on the obtained stress-strain curve, the breaking strength in each direction and the 50% modulus value were determined.

(Method for evaluating thermal shrinkage stress of ONy film) The thermal shrinkage stress of the ONy film was SII Nanotechnology-EXSTAR-TMA / SS6100, the sample width was 3 mm, the distance between chucks was 15 mm, and the temperature was 30 to 245 ° C (temperature increase rate: 10). (° C./min.). For the ONy film, the maximum heat shrinkage stress value observed at 170 to 210 ° C. was measured for each of MD and TD after conditioning for 2 hours in an environment of 23 ° C. × 50%.

(Cold-formability, evaluation method for occurrence of delamination) The cold-formability of the laminate packaging material including the ONy film was evaluated. Specifically, first, the obtained ONy film was used as a base material layer, the resin coating surface was aluminum side, aluminum foil (AA8079-O material, thickness 32 μm), and unstretched polypropylene film [pyrene film CT-P1128 (trade name) ) And Toyobo Co., Ltd., each having a thickness of 30 μm] was dry laminated (dry coating amount: 4.0 g / m ² ) to obtain a laminate packaging material. In addition, Toyo Morton Co., Ltd. TM-K55 / Toyo Morton Co., Ltd. CAT-10 (mixing ratio 100/8) was used as an adhesive for dry lamination. The laminate packaging material after dry lamination was aged at 60 ° C. for 72 hours. The laminate packaging material thus obtained was conditioned at 23 ° C. × 50% for 2 hours, and then used a compression mold (38 mm × 38 mm) with a maximum load of 10 MPa from the unstretched polypropylene film side. Molding was performed cold (normal temperature), and the maximum molding depth at which defects such as pinholes and cracks did not occur was evaluated at a pitch of 0.5 mm. About the laminated packaging material cold-molded by the above method, the surplus portion in the vicinity of the concave portion is set to 200 ° C. × 0.2 MPa × 2 sec. The film was heat-sealed under the conditions described above, and the presence or absence of delamination between the sealed nylon / aluminum foil was visually confirmed. Further, the sample was left in a high temperature and high humidity condition of 50 ° C. × 90% RH for 1 week, and it was visually confirmed whether or not delamination occurred.

Example 2
In Reference Example 1, the same procedure as in Reference Example 1 was performed except that the stretched film was placed in a heat roll and a tenter type heat treatment facility and heat treated at 195 ° C.

Reference example 3
Coating agent B: water-soluble methyl methacrylate copolymer “Rikabond” SA-R615A (Tg 67 ° C.) manufactured by Chuo Rika Kogyo Co., Ltd. and water-soluble polyepoxy compound “Denacol” EX- manufactured by Nagase Kasei Kogyo Co., Ltd. 521 (polyglycerol polyglycidyl ether) and true spherical silica fine particles “Seahoster” KE-P30 (average particle diameter 0.3 μm) manufactured by Nippon Shokubai Chemical Industry Co., Ltd. were added at a blending ratio of 75/25 / 0.5, Dilute with water.
The same procedure as in Reference Example 1 was performed except that the coating agent was changed to B in Reference Example 1.

Reference example 4
In Reference Example 1, the same procedure as in Reference Example 1 was performed except that a printing layer was provided between ONy and the aluminum foil.

Example 5
In Reference Example 1, the stretched film was placed in a heat roll and a tenter heat treatment facility, heat treated at 195 ° C., and the same procedure as in Reference Example 1 was performed except that a printing layer was provided between ONy and the aluminum foil.

Comparative Example 1
In Reference Example 1, the same procedure as in Reference Example 1 was performed except that the original fabric was not subjected to corona treatment or resin coating.

Comparative Example 2
In Reference Example 1, the same procedure as in Reference Example 1 was performed except that the stretched film was put in a heat roll and a tenter type heat treatment facility and heat treated at 220 ° C.

Comparative Example 3
In Reference Example 1, the same procedure as in Reference Example 1 was performed except that the stretched film was placed in a heat roll and a tenter type heat treatment facility and heat treated at 150 ° C.

Comparative Example 4
In Reference Example 1, the same procedure as in Reference Example 1 was carried out except that a biaxially stretched nylon film (Harden film NAP4142, thickness 25 μm) manufactured by Toyobo was used as the ONy film.

Comparative Example 5
In Reference Example 1, the same procedure as in Reference Example 1 was performed except that the original fabric was not subjected to corona treatment and resin coating, and a printing layer was provided between ONy and the aluminum foil.

As shown in Table 1, the maximum value of heat shrinkage stress at 170-210 ° C. at 170 to 210 ° C. in an ONy film coated on one side with polyurethane resin or acrylic resin is 5.0 MPa or less in both uniaxial tensile tests. In Reference Example 1, Example 2 and Reference Example 3 in which the breaking strength in all four directions is adjusted to 240 MPa or more and the 50% modulus value is adjusted to 120 MPa or more, it is possible to achieve both excellent formability and suppression of delamination. done. In Example 2 in which the breaking strength was 280 MPa or more and the 50% modulus value was 150 MPa or more, the formability could be further improved while suppressing the occurrence of delamination. Furthermore, regardless of the presence or absence of the printed layer between the ONy film and the aluminum foil, none of them was delaminated under high temperature and high humidity conditions. On the other hand, Comparative Example 1 and Comparative Example 5 in which resin coating was not performed had good moldability, but delamination occurred during molding and / or high temperature and high humidity conditions. Resin-coated Comparative Examples 2 and 4 had neither delamination during molding nor delamination under high temperature and high humidity, but were inferior in moldability compared to Reference Example 1, Example 2 and Reference Example 3. . Moreover, although the resin-coated Comparative Example 3 was excellent in moldability, the maximum value of the heat shrinkage stress at 170 to 210 ° C. was both MD and TD, or both MD and TD exceeded 5.0 MPa. The occurrence of delamination was also observed under the above conditions. Further, when the breaking strength in any of the four directions was 240 MPa or less and the 50% modulus value was 120 MPa or less, the moldability was reduced. Therefore, all of Comparative Examples 1 to 5 could not achieve both excellent moldability and suppression of delamination.

The present invention is suitably used as a main base material for packaging materials for cold forming, particularly packaging materials for battery cases such as lithium ion secondary batteries.

1 Coating device 2 Tubular drawing device nip roll 3 Tubular drawing device preheating heater 4 Tubular drawing device main heat heater 5 Tubular drawing device cooling air ring 6 Tubular drawing film

Claims (9)

After or stretching of unstretched nylon film non-heat-treated, after coating the aqueous coating material mainly composed of polyurethane resin, its crosslinker and microparticles, a highly adhesive nylon film was heat-treated ,
When the easy-adhesive nylon film is used as a base material layer, it is possible to suppress the occurrence of delamination between the base material layer and the aluminum foil layer under high temperature and high humidity and is excellent in moldability.
170 to 210 the maximum value of the thermal shrinkage stress at ℃ is MD, TD and at both 5.0MPa or less, first axis tensile test (sample width 15 mm, distance between chucks 100 mm, tension rate 200 mm / min.) In the four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) all breaking strengths are 280 MPa or more and 50% modulus value is 150 MPa or more,
The polyurethane resin, the crosslinking agent and the fine particles thereof in the aqueous coating agent are the following A, B and C, respectively, and the solid content weight ratio A / B / C = 98 to 30/2 to 70 / 0.1 A biaxially stretched nylon film, characterized in that the coating amount of the aqueous coating agent is 10 to 0.050 g / m ² in terms of dry weight after stretching.
A: Aqueous polyurethane resin containing acetylene glycol in which hydroxyl groups and methyl groups are substituted on two adjacent carbon atoms of a triple bond and / or a nonionic surfactant that is an ethylene oxide adduct thereof
B: Water-soluble polyepoxy compound
C: Fine particles having an average particle size of 0.001 to 1.0 μm A battery case packaging material for cold forming formed of at least a base material layer, a barrier layer, and a sealant layer, wherein the biaxially stretched nylon film according to claim 1 is used as the base material layer. A battery case packaging material for cold forming , wherein a coated surface of a nylon film is disposed on a barrier layer side , and the barrier layer is an aluminum foil layer . A battery case packaging material for cold forming formed of at least a base material layer, a barrier layer, and a sealant layer, wherein the biaxially stretched nylon film according to claim 1 is used as the base material layer. providing a printed layer on the coated surface of the nylon film, it placed the printed layer on the barrier layer side, and cold-formed battery case packaging material, wherein said barrier layer is an aluminum foil layer. A battery case in which the cold-forming battery case packaging material according to claim 2 or 3 is used, and a concave portion is formed by overmolding or deep drawing so that the sealant layer becomes an inner surface. A battery body, wherein the battery body is housed in a recessed portion of the battery case according to claim 4 and sealed. Constructed by laminating at least a base material layer, a barrier layer and a sealant layer in this order, it is possible to suppress the occurrence of delamination between the base material layer and the barrier layer under high temperature and high humidity and formability A battery case packaging material for cold forming, excellent in
An easily-adhesive nylon film that has been heat-treated after coating a polyurethane resin, a cross-linking agent and an aqueous coating agent mainly composed of fine particles on a non-stretched or unheated nylon film with the base material layer unstretched or stretched. The maximum value of heat shrinkage stress at 170 to 210 ° C. is 5.0 MPa or less for both MD and TD, and the four directions in the uniaxial tensile test (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.). (0 ° (MD), 45 °, 90 ° (TD), 135 °) All the breaking strengths are 280 MPa or more and the 50% modulus value is 150 MPa,
The polyurethane resin, the crosslinking agent and the fine particles thereof in the aqueous coating agent are the following A, B and C, respectively, and the solid content weight ratio A / B / C = 98 to 30/2 to 70 / 0.1 10 and the coating amount of the aqueous coating agent is 0.010 to 0.050 g / m in dry weight after stretching. ² Is a biaxially stretched nylon film,
A battery case packaging material, wherein the barrier layer is an aluminum foil layer.
A: Aqueous polyurethane resin containing acetylene glycol in which hydroxyl groups and methyl groups are substituted on two adjacent carbon atoms of a triple bond and / or a nonionic surfactant that is an ethylene oxide adduct thereof
B: Water-soluble polyepoxy compound
C: Fine particles having an average particle size of 0.001 to 1.0 μm The battery case packaging material for cold forming according to claim 6, wherein a printing layer is provided between the base material layer and the barrier layer. A battery case in which the cold-forming battery case packaging material according to claim 6 or 7 is used, and a concave portion is formed by overmolding or deep drawing so that the sealant layer is an inner surface. A battery, wherein the battery main body is housed in a recessed portion of the battery case according to claim 8 and sealed.

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