JP5658416B1 - Gas barrier film having hot water resistance and food packaging material using the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas barrier film having a hot water resistance, which does not cause delamination or a decrease in barrier properties even after a hot water treatment, and a food packaging material using the film. SOLUTION: A gas barrier film obtained by laminating at least a gas barrier layer formed by laminating a gas barrier substance on a surface of a base film and a polymer resin layer obtained by laminating a polymer resin in this order. The polymer resin is obtained by a crosslinking reaction of a coating composition containing a water-soluble polymer, a metal alkoxide, and a coupling agent, and the water-soluble polymer has a hydroxy group. A gas barrier film having hot water resistance, characterized in that it is a mixture of an acetoacetyl-modified PVA partially substituted with an acetoacetyl group and an ethylene-modified PVA partially substituted with an ethylene group of a hydroxy group, and the film Provide food packaging material using [Selection figure] None

Description

The present invention relates to a gas barrier film having hot water resistance and a food packaging material using the film, and specifically, it is possible to suppress and prevent the occurrence of delamination even under hot water treatment conditions. The present invention relates to a gas barrier film having hot water resistance capable of achieving both water vapor barrier properties and oxygen barrier properties, and a food packaging material using the film.

Conventionally, a plastic film provided with a gas barrier property (hereinafter also simply referred to as a “gas barrier film”) for protection of substances that dislike oxygen and moisture has been widely used in various applications such as packaging materials such as foods and electronic component materials. It is used. In such use, the packaging material is strongly required to have the property of suppressing or preventing the alteration of the contents.

In contrast, plastic films made of polyvinylidene chloride, polyacrylonitrile, or the like have been used as gas barrier films, but these films are no longer used because they discharge environmental harmful substances when discarded. From the viewpoint of environmental problems, it seems that it is preferable to use a plastic film made of polyvinyl alcohol (PVA). However, this film has a high gas barrier humidity dependency, that is, under high humidity conditions, Therefore, the water vapor barrier property is remarkably and easily deteriorated, so that it cannot be used in a scene that requires a high gas barrier property.

Therefore, a film in which an inorganic substance such as silicon oxide or aluminum oxide is provided on the surface of a plastic film by physical vapor deposition or chemical vapor deposition is used as a packaging material as a gas barrier film, but these gas barrier films have durability against bending. In other words, there is a problem that the barrier property is easily lowered because cracks are easily generated in the vapor deposition layer at the time of bending. In addition, since the interlayer adhesion between the plastic film and the inorganic material deposited on the surface is small, if the film is bent repeatedly, the inorganic material cannot follow the flexibility of the film, and they easily peel off, resulting in gas barrier properties. Since it was lost, there was a problem in practical use.

Various proposals have been made to deal with such problems. For example, Patent Document 1 has a composite polymer layer through an inorganic thin film layer on at least one surface of a base film of a thermoplastic resin, and the composite polymer layer includes alkoxysilane or a hydrolyzate thereof, PVA and ethylene- An invention relating to a barrier laminate film characterized by polycondensation of a coating composition containing a vinyl alcohol copolymer is disclosed. Thereby, since the pinhole produced in an inorganic vapor deposition layer and peeling by a physical pressure can be supplemented and hot water resistance can be improved, the laminated film excellent in gas barrier property and hot water resistance can be obtained.

Japanese Patent No. 4563122

However, in the gas barrier film described in Patent Document 1, the solubility of ethylene vinyl alcohol, which is one of the main components, is very low, making it difficult to prepare and reproducible solutions, and mass production and simplification are possible. It has been difficult to use at the production sites that are expected.

The present invention has been made in view of such problems. The purpose of the present invention is to use a gas barrier film having hot water resistance, which does not cause delamination or deterioration in barrier properties even when hot water treatment is performed, and the film. It is to provide food packaging materials that have been provided more easily.

In order to solve the above-mentioned problems, the invention relating to the gas barrier film having hot water resistance according to claim 1 of the present invention comprises a gas barrier layer formed by laminating at least a gas barrier substance on the surface of a base film, and a polymer. A gas barrier film obtained by laminating a polymer resin layer obtained by laminating a resin in this order, wherein the polymer resin contains a water-soluble polymer, a metal alkoxide, and a coupling agent. The water-soluble polymer obtained by a crosslinking reaction of the coating composition is an acetoacetyl-modified polyvinyl alcohol in which the hydroxy group is partially substituted with an acetoacetyl group and an ethylene-modified in which the hydroxy group is partially substituted with an ethylene group It is a mixture of polyvinyl alcohol.

The invention relating to the gas barrier film having hot water resistance according to claim 2 of the present invention is the gas barrier film having hot water resistance according to claim 1, wherein the water-soluble polymer is an acetoacetyl-modified PVA (a ) And ethylene-modified PVA (b) are mixed in such a range that the solid content ratio is (a) / (b) = 3/1 to 1/3.

The invention relating to the gas barrier film having hot water resistance according to claim 3 of the present invention is the gas barrier film having hot water resistance according to claim 1 or 2, wherein the metal alkoxide is represented by the general formula M ( OR) _n (M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element).

The invention relating to the gas barrier film having hot water resistance according to claim 4 of the present invention is the gas barrier film having hot water resistance according to any one of claims 1 to 3, wherein the coupling agent. Is a general formula YMR _m (OR) _n-1-m (where Y is a reactive functional group, M is a metal element, R is an alkyl group, n is an oxidation number of the metal element, and m is 0 or more (n-1 ) A smaller integer), which is one or more of various coupling agents.

The invention relating to the gas barrier film having hot water resistance according to claim 5 of the present invention is the gas barrier film having hot water resistance according to any one of claims 1 to 4, wherein the gas barrier substance is provided. Any one of the group consisting of silicon, titanium, tin, zinc, aluminum, indium, magnesium, or any of its oxides, nitrides, or compounds or mixtures thereof, or within the group It is any one of a plurality of oxides, nitrides, compounds, or a mixture thereof.

The invention according to claim 6 of the present invention provides a polyamide film and a sealant film on the laminated surface of the gas barrier film having hot water resistance according to any one of claims 1 to 5. A gas barrier film laminate having hot water resistance, wherein the laminate has a gas barrier property of water vapor permeability of 1 g / m ² · day or less, oxygen permeability of 0 0.1 cc / m ² · day · atm or less, and the gas barrier property after the hydrothermal treatment of the laminated body with hot water at a temperature of 100 ° C. for 30 minutes has a water vapor permeability of 1 g / m ² · day. Hereinafter, when T-type peeling is performed at a peeling speed of 300 mm / min when the oxygen permeability is 0.5 cc / m ² · day · atm or less, the peeling strength of each layer is 3 N / 15 mm before and after the hydrothermal treatment. It is the above.

The invention according to claim 7 of the present invention is a food packaging comprising the gas barrier film having hot water resistance and the gas barrier film laminate having hot water resistance according to any one of claims 1 to 6. It is characterized by being a material.

If it is a gas barrier film having hot water resistance according to the present invention, delamination does not occur even after immersion for 30 minutes with hot water at 100 ° C., and both the oxygen permeability and the water vapor permeability are maintained. Therefore, it is possible to obtain a high-performance gas barrier film excellent in hot water resistance and having both oxygen permeability and water vapor permeability. In addition, ethylene vinyl alcohol that has been conventionally used has low solubility and is difficult to prepare for mixing or the like. However, the modified PVA used in the present invention can be easily dissolved, so that it can be easily performed with high performance. Gas barrier film can be obtained.

Embodiments of the present invention will be described below. Note that the embodiment shown here is merely an example, and is not necessarily limited to this embodiment.

(Embodiment 1)
A gas barrier film having hot water resistance according to the present invention will be described as a first embodiment.

The gas barrier film having hot water resistance according to the present embodiment has a configuration in which at least a gas barrier layer and a polymer resin layer are laminated in this order on the surface of a base film.

Hereinafter, the description will be made in order.
First, the base film is a resin film that is conventionally used in gas barrier films. A polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, or a composite film of these is preferable. In this embodiment, a PET film is used.

The thickness of the base film according to the present embodiment is not particularly limited, but a thickness that does not break even if various steps in the present embodiment are performed is necessary, and finally has a high barrier property. If a certain degree of flexibility is required when the gas barrier film is obtained, it is a matter of course that it is necessary to make the thickness not more than a level that can ensure the flexibility. If this point is considered and more specifically examined, it is preferably 6 μm or more and 250 μm or less. If the film is thinner than 6 μm, there is a high possibility that the film will not be able to withstand various treatments performed when performing the various steps in the present embodiment, and the film actually obtained as a film thicker than 250 μm. This is because the flexibility becomes poor, and as a result, the packaging material becomes unsuitable. In this embodiment, it is set to 12 μm.

Next, the gas barrier layer will be described.
As the gas barrier layer according to the present embodiment, a gas barrier material that is conventionally used in a gas barrier film may be used, but preferably a group of silicon, titanium, tin, zinc, aluminum, indium, and magnesium. Any one or any of its oxides, nitrides, compounds or mixtures thereof, or any of the plurality, or any of its oxides, nitrides, compounds or mixtures thereof in the group. More specifically, for example, silicon may be used, silicon oxide, silicon nitride, silicon compound may be used, or a mixture of silicon oxide and aluminum oxide may be used. Further, it may be an oxide or nitride of an alloy of tin and indium. That is, a gas barrier layer made of a material made of these group of metals may be used. In this embodiment mode, silicon oxide is used.

Further, a gas barrier film obtained by the present embodiment by using a transparent material among the above materials, for example, silicon oxide, and making all the materials used for the gas barrier film according to the present embodiment basically transparent. The whole is also transparent. If such a gas barrier film is used as a packaging material, the contents can be easily visually recognized. Therefore, there is an advantage that not only the contents are protected from gas but also the state of the contents can be visually confirmed.

As a method of laminating the gas barrier layer, a conventionally known technique such as a physical vapor deposition method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method can be used as appropriate. A vacuum deposition method will be used.

The thickness of the gas barrier layer is preferably 5 nm or more and 40 nm or less. If the thickness is less than 5 nm, the gas barrier layer to be exhibited by the gas barrier layer itself is insufficient, and if it is thicker than 40 nm, it is not possible to improve the barrier property by increasing the thickness. This is because the flexibility is poor, which is disadvantageous in terms of cost and performance. In this embodiment, the thickness is 30 nm.

Next, the polymer resin layer will be described.
The polymer resin according to the present embodiment is obtained by crosslinking reaction of a coating composition containing a water-soluble polymer, a metal alkoxide, and a coupling agent. A stronger film can be obtained by crosslinking reaction of such components.

The water-soluble polymer according to the present embodiment is a mixture of acetoacetyl-modified PVA in which the hydroxy groups of PVA are partially substituted with acetoacetyl groups and ethylene-modified PVA in which the hydroxy groups of PVA are partially substituted with ethylene groups. It is characterized by being. Conventionally, attempts have been made to improve gas barrier properties by using a single unmodified PVA or modified PVA, a mixture of unmodified PVA and modified PVA, or a mixture of modified PVA and ethylene vinyl alcohol copolymer. Durability to gas barrier hot water treatment was insufficient. However, by mixing two types of modified PVA in which the hydroxy group is partially substituted with a functional group having high crosslinking reactivity as in the present invention and modified PVA in which the hydroxy group is partially substituted with a hydrophobic functional group, It has been found that an effect higher than the performance obtained by the composition is obtained.

This will be described below.
Since unmodified PVA becomes a strong film by a crosslinking reaction, it is widely used as a gas barrier material. However, under high humidity conditions, the gas barrier property, particularly the water vapor barrier property, is remarkably and easily deteriorated. This is because unmodified PVA alone is a reaction with only hydroxy groups, but not all hydroxy groups react, so that the cross-linking is not strong and the cross-linking is easily removed by hot water treatment.

By using a modified PVA in which a hydroxy group is substituted with a functional group having a high crosslinking reactivity in place of such an unmodified PVA, the crosslinking reaction is promoted and a film stronger than the unmodified PVA can be obtained. For example, an acetoacetyl-modified PVA in which a hydroxy group is substituted with an acetoacetyl group is more strongly cross-linked than an unmodified PVA due to a reaction between acetoacetyl groups or between an acetoacetyl group and a hydroxy group. However, since these reactions are dehydration reactions that are reversible reactions, the reverse reaction easily occurs by performing the hot water treatment, and the crosslinking is removed.

Therefore, as a result of the intensive studies by the inventors, the modified PVA in which the hydroxy group is substituted with a functional group having a high crosslinking reactivity is mixed with the modified PVA in which the hydroxy group is substituted with a hydrophobic functional group. It has been found that resistance to hot water, which could not be maintained in the past, is improved. The reason for this is not clear, but by using a modified PVA in which the hydroxy group is substituted with a hydrophobic functional group, the crosslinking density is improved, and the hydrophobic functional group can be crosslinked with other functional groups from the attack by hot water. In order to protect, it is thought that higher hot water tolerance can be exhibited.

In the modified PVA, a conventionally known functional group may be appropriately used as a functional group substituted with a hydroxy group, but an acetoacetyl group is used as a functional group having high crosslinking reactivity, and an ethylene group is used as a hydrophobic functional group. It is preferable. The acetoacetyl group has a higher reactivity than the hydroxy group, and can be made to have stronger crosslinking such as an aldehyde reaction between acetoacetyl groups or a methylol reaction between an acetoacetyl group and a hydroxy group. In addition, the ethylene group has hydrophobicity, and the above-described crosslinking with the acetoacetyl group can be protected from hot water.

At this time, the substitution rate of the hydroxy group and each functional group may be appropriately selected, but it is preferably 15% or less, more preferably 1% or more and 10% or less with respect to the entire hydroxy group. If it is such a range, the solubility to water, affinity with a solvent, and the dispersibility in a coating liquid can be maintained. In the present embodiment, both acetoacetyl-modified PVA and ethylene-modified PVA are 3%.

By using a plurality of such modified PVAs, higher hydrothermal resistance than before can be obtained simply by mixing the modified PVAs as described above, so that a high-performance gas barrier film can be obtained more simply. Moreover, the ethylene vinyl alcohol copolymer which has been used as a barrier layer polymer resin of a gas barrier film conventionally has low solubility and lacks stable productivity. However, since the modified PVA substituted with a hydroxy group used in the present invention has high solubility and can be easily prepared, a high-performance gas barrier film can be easily obtained. Furthermore, since it is not necessary to stack and a high effect can be obtained only by mixing, the number of steps and the total film thickness can be reduced, and the cost can be reduced.

The modified PVA used in the present invention can be obtained by substituting the hydroxy group of the unmodified PVA with an arbitrary functional group, and the unmodified PVA preferably has a vinyl alcohol component of 91% or more. More preferably, it is a fully saponified PVA having a vinyl alcohol component of 99% or more. By using such unmodified PVA as a base, a layer having higher coating strength and water resistance can be obtained.

In the two types of modified PVA, when the acetoacetyl-modified PVA is (a) and the ethylene-modified PVA is (b), the solid content ratio is (a) / (b) = 3/1 to 1/3. It is preferable that they are mixed in such a range. If the various components are larger than such a ratio, it becomes difficult to maintain water vapor permeability and oxygen permeability at good values and to maintain interlayer adhesion. In the present embodiment, a mixture of acetoacetyl-modified PVA and ethylene-modified PVA at a solid content ratio of 1/1 is used.

The metal alkoxide according to the present embodiment is preferably one represented by the general formula M (OR) _n . At this time, M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element. Such a metal alkoxide is not particularly limited and may be appropriately selected depending on the application and configuration. Examples of the metal element to be used include silicon, magnesium, germanium, boron, lithium, sodium, iron, gallium, Examples include phosphorus, antimony, tin, tantalum, and vanadium. Metal alkoxide is hydrolyzed by an acid catalyst, and the hydrolyzed products or dehydration condensation reaction with hydroxyl groups of the water-soluble polymer promotes the three-dimensional cross-linking reaction, and has high heat resistance and high density. It can be set as a simple film. In this embodiment, ethyl silicate is used.

The coupling agent according to the present embodiment is preferably one or more of various coupling agents represented by the general formula YMR _m (OR) _n-1-m . In this case, Y is a reactive functional group, M is a metal element, R is an alkyl group, n is an oxidation number of the metal element, and m is an integer of 0 or more and less than (n−1). Such a coupling agent is not particularly limited. Examples of the metal element used include silicon, titanium, and zirconium. Examples of the reactive functional group include an amino group, an epoxy group, a methacryl group, and vinyl. Group, mercapto group and the like. Typical examples include silane coupling agents and titanate coupling agents. Since such a coupling agent has an effect of improving the affinity between the inorganic substance and the organic substance, that is, the inorganic gas barrier layer and the organic polymer resin layer, the polymer resin is directly applied on the gas barrier layer. In addition, the adhesion between the gas barrier layer and the polymer resin layer is improved. Therefore, working efficiency is improved and delamination can be suppressed. In this embodiment, a silane coupling agent is used.

A cross-linking agent may be mixed in the polymer resin. By using a cross-linking agent, cross-linking of the modified PVA is promoted and a stronger film can be obtained. In addition, a curing catalyst may be mixed. By mixing the curing catalyst, the curing of the resin is promoted and the working efficiency is improved. As these reaction aids, conventionally known ones may be appropriately used according to the resin used.

A polymer resin can be obtained by mixing a water-soluble polymer, a metal alkoxide, and a coupling agent as described above and causing a crosslinking reaction. Then, a desired polymer resin layer is obtained by applying the resin, and as a lamination method, a technique known as a conventional wet coating method may be appropriately used. For example, bar coating method, casting method, roller coating method, spray coating method, air knife coating method, spin coating method, flow coating method, curtain coating method, direct gravure method, kiss gravure reverse method, slit reverse method, etc. . In this embodiment, the bar coating method is used.

The film thickness of the polymer resin layer is preferably 0.1 to 1 μm. If the thickness is less than 0.1 μm, the effect cannot be sufficiently exhibited. If the thickness is greater than 1 μm, the barrier property cannot be improved by increasing the thickness. Even at times, the drying process takes time, which is costly. In the present embodiment, it is 0.4 μm.

The gas barrier film having the hot water resistance according to the present embodiment obtained as described above may be a laminate in which a polyamide film and a sealant film are bonded to each other through an adhesive. Since the polyamide film is excellent in pin-resistant strength, if it is used as a packaging material for liquids, it is possible to prevent bag breakage due to hot water treatment and perforation due to the contents. Moreover, since it is excellent in toughness, the strength of the packaging material can be increased even for heavy contents. On the other hand, the sealant film is provided for heat-sealing the gas barrier film according to the present embodiment and the substrate. Here, since the bag is broken when the adhesion strength of the seal portion is low, it is necessary to select a sealant film suitable for the base material to be sealed, its application, and hot water treatment conditions. Examples of the sealant film include a polyvinyl fluoride (PVF) film, a linear low density polyethylene (LLDPE) film, an unstretched polypropylene (CPP) film, and the like. In this embodiment, an LLDPE film is used. As described above, by laminating these films, it is possible to obtain a laminate having not only gas barrier properties but also strong puncture strength and toughness and having sealing properties. In the case of lamination, these films are bonded together through an adhesive, and may be appropriately performed by a conventionally known method.

In general, the hot water resistance of a gas barrier film is evaluated by the above-described water vapor permeability, oxygen permeability, and adhesion strength before and after exposing a test piece for 30 minutes with a 100 ° C. hot water shower. The test piece was immersed in hot water at 0 ° C. for 30 minutes, and the water vapor permeability and oxygen permeability before and after that were measured by the cup method (JIS Z 0208). As a result, the gas barrier film laminate obtained by the present embodiment has a water vapor permeability of 1 g / m ² · day or less and an oxygen permeability of 0.1 cc / m ² · day before heat treatment. Even after the heat treatment, good gas barrier properties and hot water resistance such as water vapor permeability of 1 g / m ² · day or less and oxygen permeability of 0.5 cc / m ² · day or less were exhibited. Moreover, also in the adhesion strength measurement by T-type peeling at a peeling speed of 300 mm / min of the laminate, it was 3 N / 15 mm or more before and after the hot water treatment, and showed high adhesion and hot water resistance.

As described above, the gas barrier film having hot water resistance according to the present embodiment is excellent in hot water resistance, in which the gas barrier property and the adhesion are not reduced even after being immersed in hot water at 100 ° C. for 30 minutes. It is a gas barrier film. Therefore, the gas barrier film having hot water resistance according to the present embodiment can be used for food packaging materials that are subjected to hot water treatment. Further, since the solution preparation and configuration are very simple, it can be stably produced at low cost with good reproducibility.

The gas barrier film having hot water resistance according to the present invention and a laminate using the film will be described below with further examples, but the present invention is not limited to these examples.

(Base film)
As a base film, Toyobo Co., Ltd. product name "UV402" (single-sided easy-adhesion coat film) is used.

(Preparation of polymer resin)
The water-soluble polymer of the polymer resin includes acetoacetyl-modified PVA in which the hydroxy group is substituted with 3% acetoacetyl group in fully saponified PVA, and ethylene in which the hydroxy group is substituted with 3% ethylene group in fully saponified PVA. A mixture of PVA selected at each level from modified PVA and fully saponified PVA at a predetermined ratio is used. As the metal alkoxide, ethyl silicate is used, and as the coupling agent, a silane coupling agent is used. In addition, 3% dilute hydrochloric acid as a hydrolysis catalyst, N, N-dimethylbenzylamine manufactured by Tokyo Chemical Industry Co., Ltd. as a dehydration reaction catalyst, Nersem Al manufactured by Nippon Chemical Industry Co., Ltd. as a thermosetting catalyst, and Nippon Synthetic Co., Ltd. as a crosslinking agent It is assumed that Safelink SPM-02 manufactured by Chemical Industry Co., Ltd. is used.
The polymer resin is prepared according to the blending ratio shown in the blending table of Table 1. First, ethyl silicate, silane coupling agent, isopropyl alcohol (IPA), 3% dilute hydrochloric acid and N, N-dimethylbenzylamine were mixed in this order to prepare a hydrolyzed solution of ethyl silicate and silane coupling agent. / IPA mixed solution was diluted to the required solid content, and Nasem Al was mixed and stirred to obtain Liquid A. Similarly, PVA selected at each level was dispersed in water so as to have a required solid content, and heated and stirred in a warm bath to obtain a water-soluble polymer solution. After allowing the water-soluble polymer solution to cool naturally, a silane coupling agent hydrolyzed with 3% dilute hydrochloric acid and Safelink SPM-02 were mixed and stirred to obtain a liquid B. The liquid A and liquid B obtained above were mixed and stirred to obtain the desired coating liquid. The numbers in the table are weight ratios, and the PVA weight ratio is the sum of the PVA used.

(Table 1)

Example 1
On the untreated surface of the base film, 30 nm of silicon oxide was formed as a gas barrier layer using a vacuum deposition method. A polymer resin layer was applied to the surface of the gas barrier layer by a bar coater method and dried to form a 0.4 μm polymer resin layer, whereby a target gas barrier film was obtained. As the water-soluble polymer, acetoacetyl-modified PVA and ethylene-modified PVA are used, and the weight percentage concentration ratio of the solid content of each PVA is acetoacetyl-modified PVA / ethylene-modified PVA = 3/1.

(Example 2)
The target gas barrier film was obtained in the same manner as in Example 1 except that the weight% concentration ratio of the solid content of PVA in the polymer resin was acetoacetyl-modified PVA / ethylene-modified PVA = 1/1. .

Example 3
The target gas barrier film was obtained in the same manner as in Example 1 except that the solid weight% concentration ratio of PVA in the polymer resin was acetoacetyl-modified PVA / ethylene-modified PVA = 1/3. .

(Comparative Example 1)
30 nm of silicon oxide was formed as a gas barrier layer on the surface of the base film with an easy-adhesion coat using a vacuum vapor deposition method to obtain a target gas barrier film.

(Comparative Example 2)
A target gas barrier film was obtained in the same manner as in Example 1 except that only unmodified fully saponified PVA was used as the water-soluble polymer.

(Comparative Example 3)
A target gas barrier film was obtained in the same manner as in Example 1 except that only acetoacetyl-modified PVA was used as the water-soluble polymer.

(Comparative Example 4)
A target gas barrier film was obtained in the same manner as in Example 1 except that only ethylene-modified PVA was used as the water-soluble polymer.

(Comparative Example 5)
Example 1 except that acetoacetyl-modified PVA and unmodified fully saponified PVA are used as the water-soluble polymer, and the weight percent concentration ratio of the solid content is acetoacetyl-modified PVA / unmodified PVA = 1/1. The target gas barrier film was obtained in the same manner as described above.

(Comparative Example 6)
Example 1 except that ethylene-modified PVA and unmodified fully saponified PVA are used as the water-soluble polymer, and the weight percent concentration ratio of the solid content is ethylene-modified PVA / unmodified PVA = 1/1. Thus, the intended gas barrier film was obtained.

The following items were examined for each example and comparative example. The results are shown in Table 2, and the evaluation is shown in Table 3. PVA (a) in the table indicates acetoacetyl-modified PVA, PVA (b) indicates ethylene-modified PVA, and PVA (c) indicates unmodified fully saponified PVA. In addition, an evaluation sample is a 15 μm thick polyamide film (product name: “ONBC” manufactured by Unitika Ltd.) and a 50 μm thick LLDPE (Mitsui Chemicals Tosero Co., Ltd.) on the gas barrier layer side of each example and comparative example. (Product name: “TUX FC-S”) and a product obtained by dry lamination using a conventionally known method.

(Gas barrier properties)
The water vapor permeability and oxygen permeability of the sample were measured by the “cup method (JIS Z 0208)”. Next, the obtained sample was immersed in 100 degreeC hot water for 30 minutes, and the water vapor permeability and oxygen permeability after that were measured similarly. The results are described in the columns in the table where the oxygen permeability is “OTR” and the water vapor permeability is “WVTR”.

(Adhesion)
One end of the sample is fixed, the other end is pulled using an autograph (manufactured by Shimadzu Corporation, model number: AGS-100A), and the load (N / 15 mm) when the sample peels is measured. The adhesion at the boundary surface was evaluated. The measuring method was T-type peeling: tensile speed 300 mm / min. Moreover, it measured similarly about what performed the hot water process performed by the gas-barrier property test. The results of each sample are described in the column labeled “Adhesion” in the table. By the way, “3 <” and “4 <” in “Adhesion” in the table means that the sample does not peel between the layers and breaks at 3N / 15 mm or 4N / 15 mm, and the adhesion at the interface cannot be measured. It shows that. That is, the level of interlayer adhesion is 3 N / 15 mm or 4 N / 15 mm or more.

(Table 2)

(Table 3)

From the above results, it can be seen that the gas barrier film according to the present invention has higher hot water resistance than the conventional one.

Compare in detail below. In Comparative Example 1, the oxygen permeability does not satisfy the conditions before and after the hot water treatment. In Comparative Example 2 in which a polymer resin layer made of only unmodified PVA was provided, the oxygen permeability before hydrothermal treatment was improved, but the oxygen permeability, water vapor permeability, and adhesion strength after hydrothermal treatment were all deteriorated. It can be seen that unmodified PVA lacks hot water resistance. Further, in Comparative Example 3 using only acetoacetyl-modified PVA as the polymer resin, the water vapor permeability after the hot water treatment was improved, but the oxygen permeability and the adhesion strength were deteriorated. In Comparative Example 4 using only ethylene-modified PVA as the polymer resin, the oxygen permeability, water vapor permeability, and adhesion strength are all deteriorated by the hot water treatment. Similarly, in Comparative Examples 5 and 6 in which unmodified PVA and modified PVA are mixed, the required oxygen permeability, water vapor permeability, and adhesion strength are not obtained after the hydrothermal treatment. On the other hand, in Examples 1 to 3, good results were obtained before and after the hydrothermal treatment in all of oxygen permeability, water vapor permeability, and adhesion strength. That is, the adhesion strength is maintained while maintaining a good gas barrier property, and a gas barrier film with only a gas barrier layer, an unmodified PVA or a modified PVA, or a mixture of unmodified PVA and modified PVA is used as a water-soluble polymer. It can be seen that the gas barrier film of the present invention has good hot water resistance compared to the gas barrier film.

If the gas barrier film having the hot water resistance according to the present invention described above and a laminate using the film are used, the barrier property and interlayer adhesion are not deteriorated even if the hot water treatment is performed. It can be used for a packaging film that requires resistance to hot water such as food packaging.

Claims (7)

At least on the surface of the base film,
A gas barrier layer formed by laminating a gas barrier material;
A gas barrier film formed by laminating a polymer resin layer formed by laminating a polymer resin in this order,
The polymer resin is obtained by a crosslinking reaction of a coating composition containing a water-soluble polymer, a metal alkoxide, and a coupling agent,
The water-soluble polymer is a mixture of acetoacetyl-modified polyvinyl alcohol in which the hydroxy group is partially substituted with an acetoacetyl group and ethylene-modified polyvinyl alcohol in which the hydroxy group is partially substituted with an ethylene group;
A gas barrier film having hot water resistance, characterized by A gas barrier film having hot water resistance according to claim 1,
The water-soluble polymer is a range in which the solid content ratio of acetoacetyl-modified polyvinyl alcohol (a) and ethylene-modified polyvinyl alcohol (b) is (a) / (b) = 3/1 to 1/3. Mixed with
A gas barrier film having hot water resistance, characterized by A gas barrier film having hot water resistance according to claim 1 or 2,
The metal alkoxide is a metal alkoxide represented by the general formula M (OR) _n (M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element);
A gas barrier film having hot water resistance, characterized by A gas barrier film having hot water resistance according to any one of claims 1 to 3,
The coupling agent is represented by the general formula YMR _m (OR) _n-1-m (where Y is a reactive functional group, M is a metal element, R is an alkyl group, n is an oxidation number of the metal element, and m is 0 or more) (N-1) an integer smaller than 1), or one or more of various coupling agents represented by
A gas barrier film having hot water resistance, characterized by A gas barrier film having hot water resistance according to any one of claims 1 to 4,
The gas barrier substance is any one of a group consisting of silicon, titanium, tin, zinc, aluminum, indium, magnesium, or any of oxides, nitrides, compounds or mixtures thereof, or A plurality or any of its oxides, nitrides, or compounds or mixtures thereof in a group,
A gas barrier film having hot water resistance, characterized by A polyamide and a sealant film are laminated via an adhesive on the lamination surface of the gas barrier film having hot water resistance according to any one of claims 1 to 5.
A gas barrier film laminate having hot water resistance, characterized by:
The gas barrier property of the laminate is a water vapor permeability of 1 g / m ² · day or less, an oxygen permeability of 0.1 cc / m ² · day · atm or less,
And the gas barrier properties after the conducted hot water treatment of the laminate at a temperature 100 ° C. hot water 30 minutes, water vapor permeability 1g ^/ m 2 · day or less, the oxygen permeability of 0.5cc ^/ m 2 · day・ Atm or less,
And when T-type peeling is performed at a peeling speed of 300 mm / min, the peeling strength of each of the above layers is 3 N / 15 mm or more,
A gas barrier film laminate having hot water resistance, characterized by A food packaging material comprising the gas barrier film having hot water resistance and the gas barrier film laminate having hot water resistance according to any one of claims 1 to 6.