JP4864818B2 - Laminated film - Google Patents

Description

  The present invention relates to a laminated film. More specifically, the present invention relates to a laminated film in which a base film having an inorganic vapor deposition layer is coated with an aqueous ethylene / vinyl alcohol copolymer dispersion.

  Conventionally, polyester and polypropylene films have excellent film-forming properties, transparency, and moisture resistance, and are widely used as packaging materials. On the other hand, with recent advances in foods, pharmaceuticals, electronic materials, etc., packaging materials used for these are not only films, but also polyvinylidene chloride resins, ethylene / vinyl alcohol copolymers (hereinafter EVOH). A coating film coated with polyvinyl alcohol or the like has been developed. Of these, in particular, vapor deposition films on which inorganic substances such as silicon oxide and aluminum oxide are deposited have attracted attention not only because they have excellent gas barrier properties but also due to environmental considerations by not using chlorine. (See Patent Document 1 and Patent Document 2).

  Many films deposited with such inorganic materials have been proposed. However, these films are fragile, and when subjected to bending, there is a problem in that the vapor deposition layer cracks and gas barrier properties are lowered. As a solution, it has been proposed to improve the gas barrier property and prevent cracking of the vapor deposition layer by coating the surface of the vapor deposition layer with EVOH or the like (see Patent Document 3). However, as a method for coating EVOH in the present invention, a method of applying a coating solution prepared by dissolving EVOH in an alcohol-based solvent, a method of forming an extrusion coat film of EVOH, and a method of laminating are listed. The former requires consideration in terms of equipment such as EVOH melting equipment and alcohol recovery methods. The latter is also not an inexpensive and industrial method because it requires the introduction of special equipment such as a co-extruder and an extrusion laminating machine.

  On the other hand, a laminated film coated with an aqueous ethylene / vinyl alcohol copolymer dispersion has also been proposed, but the transparency of the obtained film is poor depending on the particle size of EVOH used, and the usable range is limited. Etc. (see Patent Document 4).

Japanese Patent Laid-Open No. 3-71832 Japanese Patent Laid-Open No. 10-140331 Japanese Patent Laid-Open No. 10-101826 International Publication No. 03/025058 Pamphlet

  An object of the present invention is to provide a laminated film that protects the vapor deposition surface of the vapor deposition film, improves the brittleness against bending, and is excellent in transparency.

  As a result of various studies on the above problems, the present inventors have found that an aqueous ethylene / vinyl alcohol copolymer dispersion composed of particles having a specific average particle diameter is formed on the surface of a base film having an inorganic vapor deposition layer. As a result, it was found that a laminated film having an EVOH protective layer was obtained by coating, and the present invention was completed.

That is, the present invention
(Item 1) A base film having an inorganic vapor deposition layer is coated with an aqueous ethylene / vinyl alcohol copolymer dispersion comprising particles having an average particle size of 0.01 to 0.2 μm. Laminated film.
(Item 2) The laminated film according to item 1, wherein the inorganic vapor deposition layer contains at least one selected from silicon oxide and aluminum oxide.
(Item 3) An ethylene / vinyl alcohol copolymer aqueous dispersion is an ethylene / vinyl alcohol copolymer, an ethylene / α, β-unsaturated carboxylic acid copolymer neutralized with a base, and an aqueous dispersion medium. Item 3. The laminated film according to Item 1 or 2, which contains
(Item 4) The laminated film according to item 3, wherein the aqueous ethylene / vinyl alcohol copolymer dispersion further contains at least one selected from polyvinyl alcohol and an inorganic filler.
(Item 5) In the above items 1 to 4, the haze value of the laminated film coated with the aqueous ethylene / vinyl alcohol copolymer dispersion is an increase rate of 30% or less with respect to the haze value of the base film. The laminated film according to any one of the above.
(Claim 6) An ethylene / vinyl alcohol copolymer aqueous dispersion comprises:
(1) An ethylene / vinyl alcohol copolymer and an ethylene / α, β-unsaturated carboxylic acid copolymer neutralized with a base are mixed with 5 to 65% by weight of water and 95 to 35% by weight of a water-soluble organic solvent. Heating and dissolving in a mixed solvent consisting of
(2) Adjusting the concentration of the ethylene / vinyl alcohol copolymer to 1 to 5% by mass of the solution obtained in the above step, then cooling to precipitate the ethylene / vinyl alcohol copolymer;
(3) adding water to dilute the concentration of the water-soluble organic solvent in the mixed solvent to less than 35% by mass of the total amount of water and the water-soluble organic solvent;
(4) a step of distilling off the water-soluble organic solvent;
The laminated film according to any one of Items 1 to 5, which is obtained by a production method comprising:

  In the present invention, an ethylene / vinyl alcohol copolymer aqueous dispersion composed of particles having a specific average particle diameter is formed on the vapor deposition layer surface of a film in which an inorganic substance such as silicon oxide or aluminum oxide is coated on a base film. By coating, a laminated film having excellent transparency, oxygen gas barrier property, water vapor gas barrier property, solvent resistance, and improved bending, cracking and the like can be obtained.

  In the laminated film of the present invention, an aqueous ethylene / vinyl alcohol copolymer dispersion comprising particles having an average particle diameter of 0.01 to 0.2 μm is coated on a base film having an inorganic vapor deposition layer.

  The base film constituting the laminated film of the present invention is not particularly limited as long as it is a film on which an inorganic substance can be deposited. Polyethylene terephthalate, polyamide, polyethylene, polypropylene, polyamide, (meth) acrylic resin [in the present invention, (meta Acrylic means acrylic and methacrylic], polystyrene, cellulose acetate, polycarbonate, polyvinyl chloride film or sheet, etc. Among these, polyethylene terephthalate, polyamide, and polypropylene are preferable because a vapor-deposited film having excellent properties such as gas barrier properties and transparency can be obtained. Moreover, the base film may be uniaxially stretched or biaxially stretched, and the surface thereof may be subjected to surface treatment such as corona treatment or low-temperature plasma treatment. The thickness of the base film is not particularly limited, and usually about 1 to 150 μm is used.

  Examples of the inorganic substance contained in the inorganic vapor deposition layer include inorganic oxides such as silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and magnesium oxide. These may be used independently and 2 or more types may be used together. Among these inorganic substances, silicon oxide and aluminum oxide are particularly preferable from the viewpoints of transparency, gas barrier properties, and substrate adhesion. There is no limitation in particular as a film thickness of an inorganic vapor deposition layer, For example, what is necessary is just to exist in the range of 4-300 nm as a film thickness.

  The method for depositing the inorganic material on the base film is not particularly limited, and physical vapor deposition (PVD) such as vacuum deposition, sputtering, ion spraying, plasma chemical vapor deposition, thermochemistry, etc. A known method such as a chemical vapor deposition method (CVD method) such as a vapor deposition method or a photochemical vapor deposition method can be used.

  The aqueous dispersion of ethylene / vinyl alcohol copolymer used in the present invention is not particularly limited, but ethylene / vinyl alcohol copolymer, ethylene / α, β-unsaturated carboxylic acid system neutralized with base Those containing a copolymer and an aqueous dispersion medium are preferably used.

  As an ethylene / vinyl alcohol copolymer (EVOH), ethylene is copolymerized with vinyl acetate, vinyl formate, vinyl propionate, vinyl benzoate, vinyl trifluoride acetate, vinyl bivalinate, and the like, A copolymer obtained by saponification is preferred. Moreover, 5 mol% or less of copolymerizable monomers other than ethylene and vinyl ester may be copolymerized if necessary.

  Specific examples of EVOH include saponified ethylene / vinyl acetate copolymer, saponified ethylene / vinyl formate copolymer, saponified ethylene / vinyl propionate copolymer, saponified ethylene / vinyl benzoate copolymer, ethylene / Saponified vinyl trifluoride copolymer, saponified ethylene / vinyl vinyl valerate copolymer, and the like.

  The ethylene content in EVOH is preferably 15 to 65 mol%, more preferably 25 to 45 mol%. When the ethylene content is less than 15 mol%, the storage stability of the resulting aqueous dispersion may be deteriorated. Moreover, when ethylene content rate exceeds 65 mol%, there exists a possibility that the gas barrier property of the coating film obtained may fall.

  The saponification degree of the EVOH is preferably 80 mol% or more, and more preferably 95 mol% or more. If the degree of saponification is less than 80 mol%, the gas barrier properties of the resulting coating film may be reduced.

  The higher the degree of polymerization of EVOH, the more advantageous it is to apply and use as an aqueous dispersion liquid. However, it is usually preferably 400 to 5000, more preferably 700 to 2500, and most preferably 700 to 1500. If the degree of polymerization is less than 400, the strength of the resulting coating film may be reduced. When the degree of polymerization exceeds 5000, it cannot be used, but it is not practical because it is not manufactured industrially. Here, the degree of polymerization of EVOH can be determined from the intrinsic viscosity measured at 30 ° C. in a water / phenol mixed solvent (mass ratio 15/85).

  The aqueous ethylene / vinyl alcohol copolymer dispersion used in the present invention is an ethylene / α, β- neutralized with a base for the purpose of improving the dispersion stability of EVOH particles and the film-forming property during coating. An unsaturated carboxylic acid copolymer is included.

  Examples of the ethylene / α, β-unsaturated carboxylic acid copolymer include, for example, ethylene / α, β-unsaturated which is a random copolymer or block copolymer of ethylene and α, β-unsaturated carboxylic acid. Carboxylic acid copolymer or ethylene / α, β-unsaturated carboxylic acid which is a random or block copolymer of ethylene, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester / Α, β-unsaturated carboxylic acid ester copolymer and the like.

  Examples of the α, β-unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid.

  Examples of the α, β-unsaturated carboxylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, Examples thereof include monomethyl maleate, dimethyl maleate, methyl crotonic acid, methyl fumarate and methyl itaconate.

  Specific examples of the ethylene / α, β-unsaturated carboxylic acid copolymer include ethylene / (meth) acrylic acid copolymer, ethylene / crotonic acid copolymer, ethylene / maleic acid copolymer, ethylene / fumarate. Examples thereof include acid copolymers and ethylene / itaconic acid copolymers. Among these, an ethylene / (meth) acrylic acid copolymer is preferably used from the viewpoint of a high dispersion stabilizing effect.

  Specific examples of the ethylene / α, β-unsaturated carboxylic acid / α, β-unsaturated carboxylic acid ester copolymer include ethylene / (meth) acrylic acid / methyl (meth) acrylate copolymer, ethylene / Acrylic acid / ethyl acrylate copolymer, ethylene / crotonic acid / methyl crotonic acid copolymer, ethylene / maleic acid / methyl maleate copolymer, ethylene / fumaric acid / methyl fumarate copolymer, ethylene / itaconic acid / Methyl itaconate copolymer and the like. Among these, an ethylene / acrylic acid / ethyl acrylate copolymer is preferably used from the viewpoint of a high dispersion stabilizing effect.

  These ethylene / α, β-unsaturated carboxylic acid copolymers may be used alone or in combination of two or more.

  The content ratio of α, β-unsaturated carboxylic acid in the ethylene / α, β-unsaturated carboxylic acid copolymer is not particularly limited, but is usually 5 to 30% by mass, preferably 15 to 25% by mass. It is desirable that When the content ratio of the α, β-unsaturated carboxylic acid is less than 5% by mass, the dispersion stabilizing effect may be reduced. Moreover, when the content rate of (alpha), (beta)-unsaturated carboxylic acid exceeds 30 mass%, there exists a possibility that the water resistance of an obtained coating film and gas barrier property may fall.

  The ethylene / α, β-unsaturated carboxylic acid copolymer preferably has a mass average molecular weight of 5,000 to 100,000. Even if the molecular weight is less than 5,000 or more than 1,000,000, it cannot be used as a dispersant, but it is not practical because it is not industrially produced.

  The degree of neutralization of the ethylene / α, β-unsaturated carboxylic acid copolymer with a base is not particularly limited, but is usually 30 of the carboxyl groups in the ethylene / α, β-unsaturated carboxylic acid copolymer. It is desirable that -100 mol%, preferably 40-100 mol% is neutralized. If the degree of neutralization is less than 30 mol%, the dispersion stabilizing effect may not be exhibited.

  Although it does not specifically limit as said base, Usually, alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, ammonia, an organic amine, etc. are mentioned. Among them, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferably used from the viewpoint of excellent stability of the obtained EVOH aqueous dispersion.

  The amount of the ethylene / α, β-unsaturated carboxylic acid copolymer neutralized with the base is not particularly limited, but is usually 0.01 to 20 parts by mass with respect to 100 parts by mass of EVOH, preferably 0.05 to 5 parts by mass. When the amount of the ethylene / α, β-unsaturated carboxylic acid copolymer used is less than 0.01 parts by mass, the dispersion stabilizing effect may not be exhibited. When the amount of the ethylene / α, β-unsaturated carboxylic acid copolymer used exceeds 20 parts by mass, it is effective for dispersion stability, but the gas barrier properties and water resistance of the resulting coating film are reduced. There is a fear.

  Examples of the aqueous dispersion medium for dispersing the ethylene / vinyl alcohol copolymer and the base / neutralized ethylene / α, β-unsaturated carboxylic acid copolymer include tap water, ion-exchanged water, and pure water. Is mentioned. In the present specification, water refers to ion-exchanged water unless otherwise specified.

The method for producing the aqueous ethylene / vinyl alcohol copolymer dispersion is not particularly limited. For example, (1) ethylene / α, β-unneutralized with an ethylene / vinyl alcohol copolymer and a base. A step of heating and dissolving the saturated carboxylic acid copolymer in a mixed solvent composed of 5 to 65% by mass of water and 95 to 35% by mass of a water-soluble organic solvent; (2) the solution obtained in the above step is ethylene / The step of adjusting the concentration of the vinyl alcohol copolymer to 1 to 5% by mass and then cooling to precipitate the ethylene / vinyl alcohol copolymer, (3) adding water to the water-soluble in the mixed solvent The method of diluting the density | concentration of an organic solvent to less than 35 mass% of the total amount of water and a water-soluble organic solvent, and the method of (4) distilling off the said water-soluble organic solvent are mentioned.
Examples of the water-soluble organic solvent used in the step (1) include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and tert-butyl alcohol; dihydric alcohols such as ethylene glycol and propylene glycol; Examples include trihydric alcohols such as glycerin; phenols such as phenol and cresol; amines such as ethylenediamine and trimethylenediamine; dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone. Among these, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl are preferred from the viewpoint of obtaining an aqueous dispersion having a small average particle diameter of the obtained ethylene / vinyl alcohol copolymer aqueous dispersion and excellent stability. Alcohol and tert-butyl alcohol are preferably used.

  The concentration of the water-soluble organic solvent in the mixed solvent composed of water and the water-soluble organic solvent is preferably 95 to 35% by mass, and more preferably 90 to 40% by mass. If the concentration of the water-soluble organic solvent is outside the above range, the affinity with EVOH may be reduced, making it difficult for EVOH to dissolve, or EVOH particles may aggregate when precipitated.

  The heating and melting temperature is preferably 50 to 90 ° C, more preferably 60 to 85 ° C. When the melting temperature is lower than 50 ° C., EVOH is difficult to dissolve. On the other hand, when the melting temperature is higher than 90 ° C., there is no effect corresponding to the temperature, which is not economical.

  Next, after adjusting the concentration of the ethylene / vinyl alcohol copolymer to 1 to 5% by mass, the solution obtained in the above step (1) is cooled to precipitate the ethylene / vinyl alcohol copolymer. As a method for adjusting the EVOH concentration to 1 to 5% by mass, the mixed solvent may be added and stirred and mixed, or the EVOH concentration may be adjusted to 1 to 5% by mass in advance in the preparation of step (1). Later, it may be dissolved. Subsequently, when the obtained solution is cooled to −10 to 40 ° C., preferably 0 to 30 ° C., EVOH particles crystallize without aggregation in the process, and the average particle size is 0.01 to 0.2 μm. EVOH dispersion liquid consisting of fine particles of is obtained. When the cooling temperature is lower than −10 ° C., a special cooling device is required, which is not economical. On the other hand, when the cooling temperature is higher than 40 ° C., EVOH is hardly precipitated.

  The feature of this production method is that the resin concentration during crystallization is preferably adjusted to 1 to 5% by mass, more preferably 2 to 4.7% by mass, so that the average particle size is 0.01 to 0.2 μm. The object is to obtain an aqueous dispersion composed of particles. When the resin concentration at the time of crystallization is less than 1% by mass, the particle size can be further reduced, but the productivity is low and it cannot be said to be an industrial production method. When the resin concentration at the time of crystallization is higher than 5% by mass, the particle size may increase or the water dispersion may not be obtained due to aggregation.

  Next, the concentration of the water-soluble organic solvent in the EVOH dispersion obtained by the above method is preferably less than 35% by mass of the total amount of water and the water-soluble organic solvent, more preferably by adding water. After dilution to 1 to 35% by mass, more preferably 10 to 35% by mass, the water-soluble organic solvent is distilled off. By diluting the concentration of the water-soluble organic solvent to less than 35% by mass, the particles in the dispersion become stable when the solvent is distilled off. Therefore, it is possible to perform distillation by heating at a high temperature, and the solvent can be efficiently distilled off easily and inexpensively without reducing the pressure. On the other hand, when the concentration of the water-soluble organic solvent in the EVOH dispersion is 35% by mass or more, the particles in the dispersion become unstable when heated to distill, and the particles melt and fuse to form aggregated or coarse particles. As a result, an aqueous dispersion cannot be obtained stably. Therefore, the temperature cannot be raised, and the solvent must be distilled off by a method such as distillation under reduced pressure. Although it is not clear why the particles in the dispersion are stabilized by diluting the concentration of the water-soluble organic solvent to less than 35% by mass, the concentration of the water-soluble organic solvent is reduced, so that EVOH is a mixed solvent. It is presumed that the particles cannot be dissolved and the particles can be prevented from melting and fusing.

  The temperature at the time of distilling with heating is 50-120 degreeC, Preferably it is 60-100 degreeC. When the heating temperature is lower than 50 ° C., it takes a long time to evaporate the solvent, which is not economical. Moreover, when heating temperature is higher than 120 degreeC, the particle | grains of the aqueous dispersion liquid obtained become hard and it becomes difficult to form a film.

  The average particle size of the particles contained in the aqueous ethylene / vinyl alcohol copolymer dispersion obtained by the present invention is preferably 0.01 to 0.2 μm, more preferably 0.02 to 0.17 μm. The thing with an average particle diameter of less than 0.01 micrometer cannot be obtained with an industrial method substantially. When the average particle size exceeds 0.2 μm, a laminated film of EVOH can be obtained, but the transparency and gas barrier properties of the coating film may be lowered, which may not be preferable.

  The aqueous ethylene / vinyl alcohol copolymer dispersion used in the present invention may further contain at least one selected from polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) and an inorganic filler. When PVA is applied to various substrates with an EVOH aqueous dispersion, it is dried at a low temperature or in a short time, or when a thick film coating is performed, the resulting coating film is less likely to crack and the like, Moreover, it has the effect | action which improves the gas barrier property.

  Examples of the method for adding PVA to the aqueous ethylene / vinyl alcohol copolymer dispersion include a method in which PVA is added to an aqueous ethylene / vinyl alcohol copolymer dispersion prepared in advance and mixed. . The method of mixing the aqueous ethylene / vinyl alcohol copolymer dispersion and PVA is not particularly limited, and the method of dissolving and dispersing after adding PVA to the aqueous ethylene / vinyl alcohol copolymer dispersion; / A method of mixing an aqueous vinyl alcohol copolymer dispersion and an aqueous solution of PVA dissolved in advance. In the present invention, from the viewpoint of easy dissolution and dispersion in an aqueous ethylene / vinyl alcohol copolymer dispersion and easy handling, there is a method of mixing an aqueous ethylene / vinyl alcohol copolymer dispersion and an aqueous solution of PVA. Preferably used.

  75-100 mol% is preferable and, as for the saponification degree of PVA, 85-100 mol% is more preferable. When the degree of saponification is less than 75 mol%, the strength of the resulting coating film is lowered, and the hygroscopicity is increased, and the gas barrier performance in a high humidity atmosphere may be lowered.

  The polymerization degree of PVA is preferably 300 to 3500, and more preferably 300 to 2000. When the degree of polymerization is less than 300, it is necessary to add a large amount in order to improve the film formability, which is not economical, and there is a possibility that the gas barrier property of the resulting coating film is lowered by adding a large amount. . On the other hand, when the degree of polymerization exceeds 3500, the viscosity of the EVOH aqueous dispersion becomes high, and the stability is lowered, which may cause gelation during long-term storage.

In addition, in this invention, the polymerization degree of PVA means a viscosity average polymerization degree, and is measured according to JIS-K6726. That is, after re-saponifying and purifying PVA, it can be obtained from the intrinsic viscosity [η] measured in water at 30 ° C. by the following equation.
Degree of polymerization = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  0.1-100 mass parts is preferable with respect to 100 mass parts of EVOH, and, as for the usage-amount of the said PVA, 0.2-50 mass parts is more preferable. If the amount of PVA used is less than 0.1 parts by mass, the film formability may not be improved. Moreover, when the usage-amount of PVA exceeds 100 mass parts, since it becomes easy to receive to the influence of humidity, there exists a possibility that gas barrier property may fall or the viscosity of EVOH aqueous dispersion may become high, and stability may fall.

  By further adding an inorganic filler to the aqueous ethylene / vinyl alcohol copolymer dispersion used in the present invention, a coating film having further excellent gas barrier properties can be provided.

  The reason why a coating film having a further excellent gas barrier property can be given by adding an inorganic filler is not obvious, but the inorganic filler added in the formed EVOH resin is dispersed in layers. It is presumed that the labyrinth effect by the inorganic filler is sufficiently exhibited and the gas barrier property of the coating film is further improved.

  By adding a combination of PVA and an inorganic filler to the aqueous ethylene / vinyl alcohol copolymer dispersion used in the present invention, long-term storage stability is good and the gas barrier property is even better than the former. A coating can be provided.

  The reason why it is possible to give a coating film having good long-term storage stability and further excellent gas barrier properties by adding an inorganic filler and PVA in combination is not clear, but is estimated as follows. Is done. That is, in the ethylene / vinyl alcohol copolymer aqueous dispersion, the inorganic filler is present in a stable state between EVOH and PVA, and is stored for a long period of time in order to prevent aggregation of EVOH and PVA. Presumably excellent in stability. Moreover, when it is set as a coating film, since the PVA fills the gap between the added inorganic filler and the EVOH particle as well as the action of filling the gap between the EVOH particles as described above, the denseness of the coating film is increased. It is presumed that the labyrinth effect due to the addition of the inorganic filler is sufficiently exhibited, and the gas barrier property of the coating film is further improved.

  Examples of the inorganic filler include salts of water-swellable phyllosilicate, talc, mica, clay, calcium carbonate, gypsum and the like. Among them, a salt of water-swellable phyllosilicate is preferably used because it can be easily cleaved in water to easily obtain a thin plate-like dispersion, and specific examples thereof include montmorillonite, beidellite, nontronite, saponite, hectorite, and soconite. And smectites such as stevensite and permiculite. Of these, smectite, particularly montmorillonite, is preferably used.

  The average particle diameter of the inorganic filler is preferably 0.05 to 3 μm, more preferably 0.1 to 2 μm. When the average particle diameter exceeds 3 μm, it is easy for inorganic fillers to protrude from the coated film surface when thin film coating is performed, and it is easy to inhibit the formation of a dense layer on the coated film surface. There is a risk of becoming an obstacle. On the other hand, when the average particle size is less than 0.05 μm, a sufficient maze effect is hardly exhibited, so that the gas barrier performance may be lowered.

  0.01-100 mass parts is preferable with respect to 100 mass parts of EVOH, and, as for the usage-amount of an inorganic filler, 0.5-50 mass parts is more preferable. When the usage-amount of an inorganic filler is less than 0.01 mass part, there exists a possibility that the effect to be used cannot be expected. In addition, when the amount used exceeds 100 parts by mass, the effect of improving the gas barrier property can be expected, but the stability of the aqueous ethylene / vinyl alcohol copolymer dispersion is deteriorated or the transparency of the coating film is impaired. There is.

  The method for adding the inorganic filler is not particularly limited. For example, a method in which an aqueous dispersion of an inorganic filler and an aqueous ethylene / vinyl alcohol copolymer dispersion are mixed with stirring; an aqueous dispersion of an inorganic filler in advance; Examples thereof include a method of mixing an aqueous solution of PVA and then mixing the obtained mixed solution with an aqueous dispersion of EVOH. Among them, a method of mixing an aqueous dispersion of an inorganic filler and an aqueous solution of PVA in advance and then mixing the obtained mixed solution and an aqueous dispersion of EVOH is preferably used.

  The total solid concentration in the aqueous ethylene / vinyl alcohol copolymer dispersion used in the present invention is preferably 10% by mass or more, and more preferably 15% by mass or more. The upper limit of the total solid content concentration is not particularly limited, but if the concentration is too high, the storage stability of the dispersion may decrease and the viscosity may increase. 35 mass% or less is more preferable.

  A normal surfactant or protective colloid can be added to the aqueous ethylene / vinyl alcohol copolymer dispersion used in the present invention, if necessary, as long as the object of the present invention is not hindered. In addition, aqueous dispersions of other resins, stabilizers against light or heat, pigments, lubricants, antifungal agents, film-forming aids, and the like can also be added.

  In this invention, a coating film can be formed on a base film by apply | coating and drying the said ethylene / vinyl alcohol type copolymer aqueous dispersion on the base film which has an inorganic vapor deposition layer. The thickness of the EVOH coating is usually preferably 0.02 to 20 μm, and more preferably 0.2 to 15 μm. When the thickness of the coating film is less than 0.02 μm, the gas barrier property may be lowered due to pinholes or the like. Moreover, when the thickness of a coating film exceeds 20 micrometers, it is not economical.

  The method for coating the ethylene / vinyl alcohol copolymer aqueous dispersion on the base film having the inorganic vapor deposition layer is not particularly limited, and is a casting head method, a roll coating method, an air knife coating method, a gravure roll coating method. Well-known coating methods such as a doctor roll coat method, a doctor knife coat method, a curtain flow coat method, a spray method, a dipping method, and a brush coating method can be employed.

  Examples of the method for drying and heat-treating the substrate film having the inorganic vapor deposition layer coated with the aqueous ethylene / vinyl alcohol copolymer dispersion by the above-described method include dry heat treatment methods such as an infrared irradiation method and a hot air drying method. Is mentioned. The temperature of the drying and heat treatment is preferably 30 to 230 ° C, more preferably 50 to 160 ° C, and further preferably 80 to 140 ° C. Moreover, although the time of drying and heat processing changes with temperature, 5 seconds-5 minutes are preferable normally and 15 seconds-1 minute are more preferable.

  In addition, an anchor coating agent can be applied in advance to the surface of the base film. The anchor coat agent is not particularly limited, and examples thereof include polyurethane-based and polyester-based dry laminate adhesives. Moreover, surface treatments such as corona discharge treatment, sputtering treatment, high frequency treatment, flame treatment, chromic acid treatment, and solvent etching treatment can be performed on the surface of the base film.

  Furthermore, other resin is added to the laminate (laminated film) of the present invention comprising a base film having an inorganic vapor-deposited layer obtained by the above method and a coating film obtained from an aqueous ethylene / vinyl alcohol copolymer dispersion. The layers can be further laminated by a conventionally known method. Examples of these laminating methods include an extrusion lamination method and a dry lamination method.

  In addition, a normal method of laminating an adhesive resin layer between the layers can be employed for the lamination. The adhesive resin is not particularly limited as long as it does not cause delamination in a practical stage. For example, a modified olefin polymer containing a carboxyl group; a modified olefin polymer containing a glycidyl group A modified olefin polymer containing an alkoxysilane group; a polyester resin containing a polycarboxylic acid, a polyhydric alcohol, or a hydroxycarboxylic acid as a constituent component;

  Specifically, it contains carboxyl groups such as maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene / ethyl acrylate copolymer, maleic anhydride graft modified ethylene / vinyl acetate copolymer, etc. Modified olefin polymers to be modified; glycidyl modified polyethylene, glycidyl modified polypropylene, glycidyl modified ethylene / ethyl acrylate copolymer, glycidyl modified ethylene / vinyl acetate copolymer and other modified olefin polymers; alkoxysilane Examples thereof include modified olefin polymers containing an alkoxysilane group such as modified polyethylene, alkoxysilane-modified polypropylene, and alkoxysilane-modified ethylene / vinyl acetate copolymer.

The laminated film of the present invention obtained as described above preferably has a haze value of 30% or less with respect to the haze value of the base film, and more preferably 20% or less. The transparency of the coating film is greatly influenced by the transmittance of the original base film in the evaluation by the light transmittance of the laminated film, so the haze value (X) of the original base film and the ethylene / vinyl alcohol The haze value (Y) of the laminated film coated with the system copolymer dispersion was compared, and the rate of increase was calculated and evaluated according to the following formula. If the increase rate of the haze value is 30% or less, it is possible to determine that the transparency is high because almost no difference can be discriminated in appearance. When the increase rate of the haze value exceeds 30%, the transparency of the laminated film is deteriorated, and it feels whitish.
Increase rate of haze value (%) = (Y−X) / X × 100

  Hereinafter, the present invention will be described in detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples.

  In the present invention, the average particle size was measured using a dynamic light scattering particle size distribution analyzer (Zeter Sizer Nano ZS, manufactured by Sysmex Corporation).

Production Example 1
Ethylene / acrylic acid copolymer (acrylic acid content 21% by mass) was added with water and sodium hydroxide equivalent to 100% by mol of acrylic acid and dissolved at 95 ° C. for 4 hours. Ethylene / acrylic having a concentration of 25% by mass An acid copolymer neutralized aqueous solution was obtained.

  In the dispersion tank, 8 parts by mass of the obtained aqueous ethylene / acrylic acid copolymer solution, ethylene / vinyl alcohol copolymer (ethylene content 32 mol%, saponification degree 99.5 mol%, polymerization degree 1000) 100 Part by mass, 1125 parts by mass of isopropyl alcohol and 1375 parts by mass of water were added (isopropyl alcohol concentration 45% by mass), heated to 80 ° C. and dissolved by heating.

  The obtained solution (EVOH concentration 4.0% by mass) was cooled to 5 ° C. with stirring to precipitate and disperse the particles, thereby obtaining an ethylene / vinyl alcohol copolymer dispersion. Next, 1892 parts by mass of water was added to the obtained ethylene / vinyl alcohol copolymer dispersion (isopropyl alcohol concentration: 25% by mass). Subsequently, the temperature was raised to 90 ° C. and isopropyl alcohol in the mixed solvent was distilled off by heating to obtain an aqueous ethylene / vinyl alcohol copolymer dispersion having an average particle size of 0.11 μm and a solid content concentration of 20% by mass.

Production Example 2
Ethylene / acrylic acid copolymer (acrylic acid content 21% by mass) was added with water and sodium hydroxide equivalent to 80% by mole of acrylic acid and dissolved at 95 ° C for 4 hours. An acid copolymer partially neutralized aqueous solution was obtained.

  In the dispersion tank, 8 parts by mass of the obtained partially neutralized aqueous ethylene / acrylic acid copolymer, ethylene / vinyl alcohol copolymer (ethylene content 32 mol%, saponification degree 99.5 mol%, polymerization degree 1000) 100 parts by mass, 2205 parts by mass of isopropyl alcohol and 2695 parts by mass of water were charged (isopropyl alcohol concentration 45% by mass), heated to 80 ° C. and dissolved by heating.

  The obtained solution (EVOH concentration 2.0 mass%) was cooled to 5 ° C. with stirring to precipitate and disperse the particles, thereby obtaining an ethylene / vinyl alcohol copolymer dispersion. Next, 2342 parts by mass of water was added to the obtained ethylene / vinyl alcohol-based polymer dispersion (isopropyl alcohol concentration 30% by mass). Subsequently, the temperature was raised to 90 ° C. and isopropyl alcohol in the mixed solvent was distilled off by heating to obtain an aqueous ethylene / vinyl alcohol copolymer dispersion having an average particle size of 0.07 μm and a solid concentration of 16% by mass.

Production Example 3
Ethylene / methacrylic acid copolymer (methacrylic acid content 20 mass%) was added with water and sodium hydroxide equivalent to 80 mol% methacrylic acid neutralized and dissolved at 95 ° C. for 4 hours. An acid copolymer partially neutralized aqueous solution was obtained.

  In the dispersion tank, 16 parts by mass of the obtained partially neutralized aqueous ethylene / methacrylic acid copolymer, ethylene / vinyl alcohol copolymer (ethylene content 32 mol%, saponification degree 99.5 mol%, polymerization degree 1000) 100 parts by mass, 912 parts by mass of isopropyl alcohol and 1115 parts by mass of water were added (isopropyl alcohol concentration 45% by mass), heated to 80 ° C. and dissolved by heating.

  The obtained solution (EVOH concentration 4.7 mass%) was cooled to 5 ° C. with stirring to precipitate and disperse the particles, thereby obtaining an ethylene / vinyl alcohol copolymer dispersion. Next, 1505 parts by mass of water was added to the obtained ethylene / vinyl alcohol-based polymer dispersion (isopropyl alcohol concentration 25% by mass). Subsequently, the temperature was raised to 90 ° C. and isopropyl alcohol in the mixed solvent was distilled off by heating to obtain an ethylene / vinyl alcohol copolymer aqueous dispersion having an average particle size of 0.17 μm and a solid content concentration of 30% by mass.

Production Example 4
In the same manner as in Example 1, an aqueous ethylene / vinyl alcohol copolymer dispersion having an average particle size of 0.11 μm and a solid concentration of 20% by mass was obtained.

  On the other hand, 2400 parts by weight of water is added to 100 parts by weight of polyvinyl alcohol (degree of saponification 99.3 mol%, degree of polymerization 1700), heated and dissolved at 95 ° C., cooled to room temperature, and a polyvinyl alcohol aqueous solution having a solid content concentration of 4% by weight. Got.

  100 parts by weight of the aqueous ethylene / vinyl alcohol copolymer dispersion obtained above and 30 parts by weight of the aqueous polyvinyl alcohol solution obtained above (1.2 parts by weight of polyvinyl alcohol) were stirred and mixed to obtain an average particle. An aqueous ethylene / vinyl alcohol copolymer dispersion having a diameter of 0.11 μm and a solid content concentration of 16.4% by mass was obtained.

Production Example 5
In the same manner as in Example 1, an aqueous ethylene / vinyl alcohol copolymer dispersion having an average particle size of 0.11 μm and a solid concentration of 20% by mass was obtained.

  On the other hand, 2400 parts by weight of water is added to 100 parts by weight of polyvinyl alcohol (degree of saponification 99.3 mol%, degree of polymerization 1700), heated and dissolved at 95 ° C., cooled to room temperature, and a polyvinyl alcohol aqueous solution having a solid content concentration of 4% by weight. Got. To the obtained polyvinyl alcohol aqueous solution, 2500 parts by mass of a separately prepared aqueous dispersion of montmorillonite having a solid content concentration of 4% by mass and an average particle size of 0.3 μm was added with stirring to obtain a polyvinyl alcohol aqueous solution in which montmorillonite was dispersed. It was.

  100 parts by mass of the aqueous ethylene / vinyl alcohol copolymer dispersion obtained above and 45 parts by mass of an aqueous polyvinyl alcohol solution in which the montmorillonite obtained above was dispersed (content of montmorillonite 0.9 parts by mass, inclusion of polyvinyl alcohol) The mixture was stirred and mixed to obtain an aqueous ethylene / vinyl alcohol copolymer dispersion having an average particle size of 0.11 μm and a solid concentration of 15% by mass.

Production Example 6
Ethylene / acrylic acid copolymer (acrylic acid content 21% by mass) was added with water and sodium hydroxide equivalent to 100% by mol of acrylic acid and dissolved at 95 ° C. for 4 hours. Ethylene / acrylic having a concentration of 25% by mass An acid copolymer neutralized aqueous solution was obtained.

  In the dispersion tank, 8 parts by mass of the obtained aqueous ethylene / acrylic acid copolymer solution, ethylene / vinyl alcohol copolymer (ethylene content 32 mol%, saponification degree 99.5 mol%, polymerization degree 1000) 100 Part by mass, 705 parts by mass of isopropyl alcohol and 862 parts by mass of water were added (isopropyl alcohol concentration 45% by mass), heated to 80 ° C. and dissolved by heating.

  The obtained solution (EVOH concentration 6.0 mass%) was cooled to 5 ° C. with stirring to precipitate and disperse the particles, thereby obtaining an ethylene / vinyl alcohol copolymer dispersion. Next, 1145 parts by mass of water was added to the resulting ethylene / vinyl alcohol-based polymer dispersion (isopropyl alcohol concentration 25% by mass). Subsequently, the temperature was raised to 90 ° C., and the isopropyl alcohol in the mixed solvent was distilled off by heating to obtain an aqueous ethylene / vinyl alcohol copolymer dispersion having an average particle size of 0.3 μm and a solid content concentration of 20% by mass.

Examples 1-5 and Comparative Example 1
Using a bar coder (No. 3), apply the ethylene / vinyl alcohol copolymer dispersion obtained in Production Examples 1 to 6 to the vapor-deposited surface of a polyethylene terephthalate film (film thickness 12 μm) on which aluminum oxide has been deposited. And heated and dried at 120 ° C. for 30 seconds to obtain a laminated film. The surface state of the obtained laminated film was observed using an electron microscope (JSM-6390LA type, manufactured by JEOL Ltd.). Moreover, the haze value was measured using the haze meter (DH-300A, Nippon Denshoku Industries Co., Ltd.), and the increase rate was calculated. These results are shown in Table 1.

  It turns out that all the laminated films of an Example are haze values within 30% of increase, and are excellent in transparency.

  The laminated film of the present invention has excellent transparency, gas barrier properties, oil resistance, chemical resistance, for example, containers such as cups, tubes, trays, bottles, general food packaging, pharmaceutical packaging, retort It is extremely suitable for food packaging.

Claims (6)

  A laminated film, wherein a base film having an inorganic vapor deposition layer is coated with an aqueous ethylene / vinyl alcohol copolymer dispersion comprising particles having an average particle diameter of 0.01 to 0.2 μm.   The laminated film according to claim 1, wherein the inorganic vapor deposition layer contains at least one selected from silicon oxide and aluminum oxide.   The aqueous ethylene / vinyl alcohol copolymer dispersion contains an ethylene / vinyl alcohol copolymer, an ethylene / α, β-unsaturated carboxylic acid copolymer neutralized with a base, and an aqueous dispersion medium. Item 3. The laminated film according to Item 1 or 2.   The laminated film according to claim 3, wherein the aqueous ethylene / vinyl alcohol copolymer dispersion further contains at least one selected from polyvinyl alcohol and an inorganic filler.   The haze value of the laminated film coated with the aqueous ethylene / vinyl alcohol copolymer dispersion is an increase rate of 30% or less with respect to the haze value of the base film. A laminated film according to 1. Ethylene / vinyl alcohol copolymer aqueous dispersion
(1) An ethylene / vinyl alcohol copolymer and an ethylene / α, β-unsaturated carboxylic acid copolymer neutralized with a base are mixed with 5 to 65% by weight of water and 95 to 35% by weight of a water-soluble organic solvent. Heating and dissolving in a mixed solvent consisting of
(2) Adjusting the concentration of the ethylene / vinyl alcohol copolymer to 1 to 5% by mass of the solution obtained in the above step, then cooling to precipitate the ethylene / vinyl alcohol copolymer;
(3) adding water to dilute the concentration of the water-soluble organic solvent in the mixed solvent to less than 35% by mass of the total amount of water and the water-soluble organic solvent;
(4) a step of distilling off the water-soluble organic solvent;
The laminated film according to any one of claims 1 to 5, which is obtained by a production method comprising: