JP2024005555A - Gas barrier laminate and packaging bag - Google Patents

Abstract

To provide a gas barrier laminate and a packaging bag that are capable of exhibiting good gas barrier properties even after retort processing.SOLUTION: A gas barrier laminate comprises: a barrier layer with a base material on which a barrier coat is provided; a sealant layer overlapping the barrier layer; and an adhesive layer bonding the barrier layer and the sealant layer. After the base material is exposed to 120°C for 15 minutes, the thermal shrinkage of the base material in the MD direction as determined by the specified formula (1) is 1% or more, and the hardness of the adhesive layer as measured by the nanoindentation method after retort processing is performed on the gas barrier laminate is greater than or equal to 0.1 MPa and less than 0.9 MPa.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a gas barrier laminate and a packaging bag.

BACKGROUND ART Conventionally, from the viewpoint of protecting the contents wrapped in packaging materials, laminates having gas barrier properties such as oxygen barrier properties and water vapor barrier properties (gas barrier laminates) have been used. For example, Patent Document 1 below describes a gas barrier laminate including a resin base material, a gas barrier deposited layer provided on the resin base material and mainly containing an inorganic compound, and a gas barrier coating layer provided on the gas barrier deposited layer. A film is disclosed.

Patent No. 4200972

When a gas barrier laminate as described above is subjected to retort treatment, there is a problem in that the gas barrier properties tend to deteriorate.

An object of one aspect of the present disclosure is to provide a gas barrier laminate and a packaging bag that can exhibit good gas barrier properties even after retort treatment.

A gas barrier laminate according to one aspect of the present disclosure includes a barrier layer having a base material provided with a barrier coat, a sealant layer overlapping the barrier layer, and an adhesive layer bonding the barrier layer and the sealant layer. It is. After exposing the base material at 120°C for 15 minutes, the heat shrinkage rate of the base material in the MD direction determined by the following formula (1) is 1% or more, and after performing retort treatment on the gas barrier laminate, nano The hardness of the adhesive layer measured by an indentation method is 0.1 MPa or more and less than 0.9 MPa.
Thermal contraction rate in MD direction (%) = (MD direction length before heating - MD direction length after heating) / MD direction length before heating × 100 ... (1)

According to this gas barrier laminate, the hardness of the adhesive layer measured by a nanoindentation method after retorting the gas barrier laminate is 0.1 MPa or more and less than 0.9 MPa. Thereby, by using a base material having a heat shrinkage rate of 1% or more in the MD direction, even if the base material expands and contracts due to retort treatment, the adhesive layer can follow it well. Therefore, damage to the barrier coat caused by cracks in the adhesive layer can be suppressed. Therefore, it is possible to provide a gas barrier laminate that can exhibit excellent gas barrier properties even after retort treatment.

The barrier layer further includes an anchor coat layer and a vapor deposited layer located between the substrate and the barrier coat, and the anchor coat layer may be located between the substrate and the vapor deposited layer. In this case, the gas barrier properties of the gas barrier laminate can be improved.

The thickness of the vapor deposited layer may be 5 nm or more and 80 nm or less. In this case, gas barrier properties can be improved while preventing cracks in the deposited layer.

The hardness of the adhesive layer measured by a nanoindentation method before the retort treatment may be 1.0 MPa or more.

The thickness of the adhesive layer may be 0.5 μm or more and 10 μm or less. In this case, the gas barrier laminate can be easily made into a monomaterial while satisfactorily suppressing peeling between the barrier layer and the sealant layer.

Each of the base material and the sealant layer is a polyolefin film, and the proportion of the total mass of polyolefin in the gas barrier laminate may be 90% by mass or more. In this case, monomaterialization is realized.

The base material may be a stretched polypropylene film, and the sealant layer may be an unstretched polypropylene film. In this case, the laminate has excellent heat resistance against retort processing and the like.

The gas barrier laminate further includes an outermost layer that overlaps the barrier layer, and a second adhesive layer that adheres the outermost layer and the barrier layer, the adhesive layer that adheres the base material and the sealant layer, and the second adhesive layer that adheres the base material and the sealant layer. may adhere the barrier coat and the outermost layer. In this case, even after retort treatment, gas barrier properties can be better exhibited. Additionally, the barrier layer can be protected by the outermost layer.

After exposing the gas barrier laminate to 120°C for 15 minutes, the thermal contraction rate of the outermost layer in the MD direction determined by equation (1) is 1% or more, and after performing retort treatment on the gas barrier laminate, nano The hardness of the second adhesive layer measured by an indentation method may be 0.1 MPa or more and less than 0.9 MPa. In this case, even if the outermost layer expands and contracts due to retort processing, the second adhesive layer follows suit. Therefore, damage to the barrier coat due to the occurrence of cracks in the second adhesive layer can be suppressed.

One aspect of the present disclosure may provide a packaging bag that is a bag made of the gas barrier laminate described above.

According to the present disclosure, it is possible to provide a gas barrier laminate and a packaging bag that can exhibit excellent gas barrier properties even after retort processing.

FIG. 1(a) is a schematic plan view of a laminate according to one embodiment, and FIG. 1(b) is a schematic cross-sectional view showing the laminate according to one embodiment. FIG. 2 is a schematic front view of an example of a packaging bag. FIG. 3 is a schematic cross-sectional view showing a laminate according to a modified example. FIG. 4 is a schematic diagram showing a method for measuring the thermal shrinkage rate during oven heating.

Hereinafter, preferred embodiments of the present disclosure will be described in detail, with reference to the drawings as the case may be. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

<Laminated body>
FIG. 1(a) is a schematic plan view of a laminate according to one embodiment, and FIG. 1(b) is a schematic cross-sectional view showing the laminate according to one embodiment. A laminate 1 shown in FIGS. 1(a) and 1(b) is a sheet-like member (gas barrier laminate) having gas barrier properties, and is a sheet-like packaging material used, for example, in manufacturing packaging bags. The laminate 1 can be suitably used, for example, in applications where heat treatment such as retort treatment and boiling treatment is performed.

Retort processing is a method of sterilizing microorganisms such as mold, yeast, and bacteria under pressure in order to generally preserve foods, medicines, and the like. Usually, packaging bags containing foods, etc. are subjected to pressure sterilization treatment at 105 to 140°C and 0.15 to 0.30 MPa for 10 to 120 minutes. There are two types of retort devices: a steam type that uses heated steam and a hot water type that uses pressurized heated water. Boiling is a method of sterilizing foods, medicines, etc. with moist heat to preserve them. Normally, a packaging bag containing foods, etc. is subjected to moist heat sterilization treatment at 60 to 100°C and under atmospheric pressure for 10 to 120 minutes, depending on the contents. The boiling process is usually performed at 100°C or lower using a hot water bath. There are two methods: a batch method, in which the material is immersed in a hot water tank at a constant temperature and treated for a certain period of time, and then taken out, and a continuous method, in which the material is passed through the hot water tank in a tunnel.

The laminate 1 includes a barrier layer 10, a sealant layer 20, and an adhesive layer 30. The barrier layer 10 and the sealant layer 20 are laminated on each other and bonded together with an adhesive layer 30. In the laminate 1, a barrier layer 10, an adhesive layer 30, and a sealant layer 20 are laminated in this order. Hereinafter, as shown in FIG. 1(a), the direction MD is defined as the flow direction (longitudinal direction) of the laminate 1, and the direction TD is defined as the width direction (lateral direction) of the laminate 1. Further, a direction perpendicular to both the directions MD and TD is defined as the lamination direction of the members included in the laminate 1.

[Barrier layer 10]
The barrier layer 10 is a member that functions as a support in the laminate 1 and exhibits gas barrier properties against gases such as water vapor and oxygen. As shown in FIG. 1, the barrier layer 10 includes a base material 11, an adhesive layer 12, a vapor deposition layer 13, and a barrier coat 14. In the barrier layer 10, a base material 11, an adhesive layer 12, a vapor deposition layer 13, and a barrier coat 14 are laminated in this order. Therefore, the adhesion layer 12 and the vapor deposition layer 13 are located between the base material 11 and the barrier coat 14 in the lamination direction, and the adhesion layer 12 is located between the base material 11 and the vapor deposition layer 13. . In this embodiment, the barrier coat 14 of the barrier layers 10 is closest to the adhesive layer 30 in the lamination direction. Therefore, among the barrier layers 10, the base material 11 is farthest from the adhesive layer 30 in the lamination direction.

[Base material 11]
The base material 11 is a plastic member that functions as the outermost layer in the laminate 1. The thickness of the base material 11 is not particularly limited. Depending on the application, the thickness can be set to 6 to 200 μm, but from the viewpoint of reducing material to reduce environmental impact, and from the viewpoint of obtaining excellent heat resistance, impact resistance, and excellent gas barrier properties, It may be 9-50 μm, it may be 12-38 μm, it may be 18-30 μm.

From the viewpoint of suitability for recycling of the laminate 1, the base material 11 is, for example, a polyolefin film. In this embodiment, the base material 11 may include or be made of a polypropylene film. The polypropylene film may be an acid-modified polypropylene film obtained by graft-modifying polypropylene using an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like. Further, as the polypropylene, polypropylene resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-α-olefin copolymer, etc. can be used.

Various additives such as a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent may be added to the polypropylene film constituting the base material 11.

The polypropylene film constituting the base material 11 may be a stretched film or a non-stretched film. However, from the viewpoint of impact resistance, heat resistance, water resistance, dimensional stability, etc., the polypropylene film is preferably a stretched polypropylene film. Thereby, it is possible to suppress the base material 11 from being thermally fused in the heat sealing process during bag manufacturing. Further, the laminate 1 can be more suitably used in applications where heat treatment such as retort treatment and boiling treatment is performed. The stretching method is not particularly limited, and any method may be used as long as it can provide a dimensionally stable film, such as inflation stretching, uniaxial stretching, or biaxial stretching.

The laminated surface of the base material 11 may be subjected to various pretreatments such as corona treatment, plasma treatment, flame treatment, etc., or may be provided with a coating layer such as an easy-adhesion layer, as long as the barrier performance is not impaired.

[Adhesion layer]
The adhesion layer 12 functions as a layer (anchor coat layer) that can improve the adhesion performance of the vapor deposited layer 13 on the base material 11 and is provided directly above the base material 11 . Therefore, the adhesive layer 12 is located between the base material 11 and the vapor deposition layer 13. By providing the adhesive layer 12, the smoothness of the surface of the barrier layer 10 on which the vapor deposition layer 13 is provided can be improved. In addition, by improving the smoothness, it becomes easier to form the vapor deposition layer 13 uniformly without defects, and it becomes easier to exhibit high barrier properties. The adhesion layer 12 can be formed using, for example, an anchor coating agent.

Examples of the anchor coating agent include polyester polyurethane resins, polyether polyurethane resins, and the like. As the anchor coating agent, polyester-based polyurethane resin is preferable from the viewpoint of heat resistance and interlayer adhesive strength.

The thickness of the adhesive layer 12 is not particularly limited, but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.03 to 3 μm, and preferably in the range of 0.05 to 2 μm. Particularly preferred. When the thickness of the adhesion layer 12 is at least the above lower limit, a more sufficient interlayer adhesive strength tends to be obtained, while when it is at most the above upper limit, desired gas barrier properties tend to be easily exhibited.

As a method for coating the adhesive layer 12 on the base material 11, any known coating method can be used without any particular restriction, and examples include a dipping method, a method using a spray, a coater, a printing machine, a brush, etc. Can be mentioned. In addition, the types of coaters and printing machines used in these methods and their coating methods include gravure coaters such as direct gravure method, reverse gravure method, kiss reverse gravure method, and offset gravure method, reverse roll coater, and microgravure. Examples include a coater, a chamber doctor coater, an air knife coater, a dip coater, a bar coater, a comma coater, and a die coater.

As for the coating amount of the adhesive layer 12, it is preferable that the mass per 1 m ² after coating and drying the anchor coating agent is 0.01 to 5 g/m ² , and 0.03 to 3 g/m ² . It is more preferable that there be. When the mass per 1 m ² after coating and drying the anchor coating agent is above the above lower limit, film formation tends to be sufficient, while when it is below the above upper limit, it is sufficiently easy to dry and the solvent is removed. It tends to be difficult to remain.

Methods for drying the adhesive layer 12 are not particularly limited, but include natural drying, drying in an oven set at a predetermined temperature, and a dryer attached to the coater, such as an arch dryer, a floating dryer, and a drum dryer. , a method using an infrared dryer, etc. can be mentioned. Further, the drying conditions can be appropriately selected depending on the drying method. For example, in the case of drying in an oven, it is preferable to dry at a temperature of 60 to 100° C. for about 1 second to 2 minutes.

As the adhesive layer 12, a polyvinyl alcohol resin can be used instead of the polyurethane resin described above. The polyvinyl alcohol resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit, and examples thereof include polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH).

As PVA, for example, vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate can be polymerized alone. , followed by saponified resins. The PVA may be a copolymerized or post-modified modified PVA. Modified PVA can be obtained, for example, by copolymerizing a vinyl ester and an unsaturated monomer copolymerizable with the vinyl ester, followed by saponification. Examples of unsaturated monomers copolymerizable with vinyl ester include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; 3-buten-1-ol, 4-pentyn-1-ol , 5-hexen-1-ol, etc.; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid; acrylonitrile, methacrylonitrile, etc. Nitriles; amides such as diacetone acrylamide, acrylamide, and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid; alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene Vinyl compounds such as carbonate, 2,2-dialkyl-4-vinyl-1,3-dioquinrane, glycerin monoallyl ether, 3,4-diacetoxy-1-butene; vinylidene chloride, 1,4-diacetoxy-2-butene, Examples include vinylene carbonate.

The degree of polymerization of PVA is preferably 300 to 3,000. If the degree of polymerization is less than 300, the barrier properties tend to deteriorate, and if it exceeds 3000, the viscosity is too high and the coating suitability tends to deteriorate. The degree of saponification of PVA is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. Moreover, the degree of saponification of PVA may be 100 mol% or less, or 99.9 mol% or less. The degree of polymerization and saponification of PVA can be measured according to the method described in JIS K 6726 (1994).

EVOH is generally a copolymer of ethylene and acid vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate. Obtained by saponifying the union.

The degree of polymerization of EVOH is preferably 300 to 3,000. If the degree of polymerization is less than 300, the barrier properties tend to deteriorate, and if it exceeds 3000, the viscosity is too high and the coating suitability tends to deteriorate. The degree of saponification of the vinyl ester component of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. Further, the degree of saponification of EVOH may be 100 mol% or less, or 99.9 mol% or less. The degree of saponification of EVOH is determined by nuclear magnetic resonance (1H-NMR) measurement from the peak area of hydrogen atoms contained in the vinyl ester structure and the peak area of hydrogen atoms contained in the vinyl alcohol structure.

The ethylene unit content of EVOH is 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and particularly preferably 25 mol% or more. Further, the ethylene unit content of EVOH is preferably 65 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. When the ethylene unit content is 10 mol % or more, gas barrier properties or dimensional stability under high humidity can be maintained favorably. On the other hand, when the ethylene unit content is 65 mol% or less, gas barrier properties can be improved. The ethylene unit content of EVOH can be determined by NMR method.

When polyvinyl alcohol resin is used as the adhesive layer 12, methods for forming the adhesive layer 12 include coating using a polyvinyl alcohol resin solution, multilayer extrusion, and the like.

[Vapour-deposited layer 13]
The vapor deposition layer 13 is a layer (gas barrier layer) that exhibits gas barrier properties against water vapor and oxygen, and contains at least one of a metal and an inorganic oxide. The vapor deposition layer 13 is provided directly above the adhesive layer 12 . The vapor deposition layer 13 may have a single layer structure or a laminated structure. For this reason, the vapor deposition layer 13 includes at least one of a metal vapor deposition layer and an inorganic oxide layer. When the vapor deposition layer 13 includes a metal vapor deposition layer, examples of the metal contained in the metal vapor deposition layer include aluminum, stainless steel, and the like. When the vapor deposition layer 13 includes an inorganic oxide layer, examples of the inorganic oxide contained in the inorganic oxide layer include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoint of transparency and barrier properties, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. Further, from the viewpoint of excellent tensile stretchability during processing, it is preferable that the inorganic oxide layer is a layer using silicon oxide. By using the inorganic oxide layer, high barrier properties can be obtained with a very thin layer that does not affect the recyclability of the laminate 1.

When the vapor deposition layer 13 is an inorganic oxide layer using silicon oxide, the O/Si ratio of the inorganic oxide layer is preferably 1.7 or more. When the O/Si ratio is 1.7 or more, the metal Si content is suppressed and good transparency is easily obtained. Further, the O/Si ratio is preferably 2.0 or less. When the O/Si ratio is 2.0 or less, the crystallinity of SiO becomes high and the inorganic oxide layer can be prevented from becoming too hard, and good tensile resistance can be obtained. Thereby, it is possible to suppress the occurrence of cracks in the inorganic oxide layer when layering the barrier coat 14. In addition, even after forming into a packaging bag, the base material 11 may shrink due to heat during boiling or retort processing, but since the O/Si ratio is 2.0 or less, the inorganic oxide layer can follow the shrinkage. It is possible to suppress the deterioration of barrier properties. From the viewpoint of obtaining these effects more fully, the O/Si ratio of the inorganic oxide layer is preferably 1.75 or more and 1.9 or less, and more preferably 1.8 or more and 1.85 or less.

When the vapor deposition layer 13 is an inorganic oxide layer using silicon oxide, the O/Si ratio of the inorganic oxide layer can be determined by X-ray photoelectron spectroscopy (XPS). For example, the measurement device is an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., product name: JPS-90MXV), the X-ray source is non-monochromatic MgKα (1253.6eV), and the X-ray source is 100W (10kV-10mA). ) can be measured using the X-ray output. Relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used for quantitative analysis to determine the O/Si ratio, respectively.

The thickness of the vapor deposition layer 13 is, for example, 5 nm or more and 80 nm or less. When the thickness of the vapor deposition layer 13 is 5 nm or more, sufficient water vapor barrier properties can be obtained. Furthermore, when the thickness of the vapor deposited layer 13 is 80 nm or less, it is possible to suppress the occurrence of cracks due to deformation due to internal stress of the thin film, and to suppress deterioration of water vapor barrier properties. It should be noted that if the thickness of the vapor deposited layer 13 exceeds 80 nm, the cost tends to increase due to an increase in the amount of material used, a longer film formation time, etc., which is not preferable from an economical point of view. From the same viewpoint as above, the thickness of the vapor deposition layer 13 may be 20 nm or more and 40 nm or less.

The vapor deposition layer 13 can be formed, for example, by vacuum film formation. In vacuum film formation, a physical vapor deposition method or a chemical vapor deposition method can be used. Examples of the physical vapor deposition method include, but are not limited to, a vacuum evaporation method, a sputtering method, an ion plating method, and the like. Examples of the chemical vapor deposition method include, but are not limited to, a thermal CVD method, a plasma CVD method, a photo CVD method, and the like.

The above vacuum film formation methods include resistance heating vacuum evaporation, EB (Electron Beam) heating vacuum evaporation, induction heating vacuum evaporation, sputtering, reactive sputtering, dual magnetron sputtering, and plasma chemical vapor deposition. (PECVD method) etc. are particularly preferably used. However, in terms of productivity, the vacuum deposition method is currently the best. As a heating means for the vacuum evaporation method, it is preferable to use one of an electron beam heating method, a resistance heating method, and an induction heating method.

[Barrier coat 14]
The barrier coat 14 is a coating layer having gas barrier properties (gas barrier coating layer), and is provided on the base material 11 . The barrier coat 14 is, for example, a composition for forming a gas barrier coating layer containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof. This layer is formed using a coating agent (hereinafter also referred to as a coating agent).

The coating agent preferably contains at least a silane coupling agent or a hydrolyzate thereof, and preferably contains a hydroxyl group-containing polymer compound, a metal alkoxide and It is more preferable to contain at least one selected from the group consisting of hydrolysates thereof, a silane coupling agent or a hydrolyzate thereof, and a hydroxyl group-containing polymer compound or a hydrolyzate thereof, a metal alkoxide or It is more preferable to contain a hydrolyzate thereof and a silane coupling agent or a hydrolyzate thereof. For example, the coating agent can be prepared by directly or pre-hydrolyzing a metal alkoxide and a silane coupling agent in a solution in which a water-soluble polymer containing a hydroxyl group is dissolved in an aqueous (water or water/alcohol mixed) solvent. It can be prepared by mixing those that have been subjected to a treatment such as oxidation.

Each component contained in the coating agent for forming the barrier coat 14 will be explained in detail. Examples of the hydroxyl group-containing polymer compound used in the coating agent include polyvinyl alcohol, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, and sodium alginate. Among these, it is preferable to use polyvinyl alcohol (PVA) as the coating agent for the barrier coat 14 because it has particularly excellent gas barrier properties.

From the viewpoint of obtaining excellent gas barrier properties, the barrier coat 14 may be formed from a composition containing at least one selected from the group consisting of a metal alkoxide represented by the following general formula (I) and a hydrolyzate thereof. preferable.
M(OR ¹ ) _m (R ² ) _nm ...(I)
In the above general formula (I), R ¹ and R ² are each independently a monovalent organic group having 1 to 8 carbon atoms, and are preferably an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, and Zr. m is an integer from 1 to n. In addition, when a plurality of R ¹ or R ² exist, R ¹ or R ² may be the same or different.

Specific examples of the metal alkoxide include tetraethoxysilane [Si(OC ₂ H ₅ ) ₄ ], triisopropoxyaluminum [Al(O-2′-C ₃ H ₇ ) ₃ ], and the like. Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

Examples of the silane coupling agent include compounds represented by the following general formula (II).
Si(OR ¹¹ ) _p (R ¹² ) _3-p R ¹³ ...(II)
In the above general formula (II), R ¹¹ represents an alkyl group such as a methyl group or an ethyl group, and R ¹² represents an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkyl group substituted with an acryloxy group, or a methacryloxy group. represents a monovalent organic group such as an alkyl group substituted with a group, R ¹³ represents a monovalent organic functional group, and p represents an integer of 1 to 3. In addition, when a plurality of R ¹¹ or R ¹² exist, R ¹¹ or R ¹² may be the same or different. The monovalent organic functional group represented by ^R13 is a monovalent organic functional group containing a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or an isocyanate group. Examples include groups.

Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ- Examples include silane coupling agents such as methacryloxypropylmethyldimethoxysilane.

Moreover, the silane coupling agent may be a polymer obtained by polymerizing the compound represented by the above general formula (II). The multimer is preferably a trimer, more preferably 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate. This is a condensation polymer of 3-isocyanatealkylalkoxysilane. It is known that in this 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurate, the isocyan moiety has no chemical reactivity, but the reactivity is ensured by the polarity of the nurate moiety. Generally, like 3-isocyanate alkyl alkoxylane, it is added to adhesives, etc., and is known as an adhesion improver. Therefore, by adding 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate to a hydroxyl group-containing polymer compound, the water resistance of the gas barrier coating layer can be improved due to hydrogen bonding. 3-Isocyanate alkyl alkoxyrane has high reactivity and low liquid stability, whereas 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurate is not water-soluble due to the polarity of the nurate moiety. However, it is easily dispersed in aqueous solutions and can maintain stable liquid viscosity. Furthermore, the water resistance properties of 3-isocyanatealkylalkoxyrane and 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate are equivalent.

1,3,5-Tris(3-trialkoxysilylalkyl)isocyanurate is sometimes produced by thermal condensation of 3-isocyanatepropylalkoxysilane, and may also contain the raw material 3-isocyanatepropylalkoxysilane. However, there is no particular problem. More preferred is 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate, and more preferred is 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate. 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is practically advantageous because the methoxy group has a high hydrolysis rate and those containing a propyl group are available at relatively low cost.

Additionally, known additives such as isocyanate compounds, dispersants, stabilizers, viscosity modifiers, colorants, etc. can be added to the coating agent as necessary, within a range that does not impair gas barrier properties. .

The thickness of the barrier coat 14 is preferably 50 to 1000 nm, more preferably 100 to 500 nm. When the thickness of the barrier coat 14 is 50 nm or more, it tends to be able to obtain more sufficient gas barrier properties, and when it is 1000 nm or less, it tends to be able to maintain sufficient flexibility.

The coating liquid for forming the barrier coat 14 can be used, for example, by a dipping method, a roll coating method, a gravure coating method, a reverse gravure coating method, an air knife coating method, a comma coating method, a die coating method, a screen printing method, a spray coating method, or a gravure coating method. It can be applied by an offset method or the like. A coating formed by applying this coating liquid can be dried by, for example, a hot air drying method, a hot roll drying method, a high frequency irradiation method, an infrared irradiation method, a UV irradiation method, or a combination thereof.

The temperature at which the coating film is dried can be, for example, 50 to 150°C, preferably 70 to 100°C. By setting the drying temperature within the above range, it is possible to further suppress the occurrence of cracks in the vapor deposited layer 13 and the barrier coat 14, and it is possible to exhibit excellent barrier properties.

The barrier coat 14 may be formed using a coating agent containing a polyvinyl alcohol resin and a silane compound. An acid catalyst, an alkali catalyst, a photoheavy initiator, etc. may be added to the coating agent as necessary.

The polyvinyl alcohol resin is as described above. In addition, examples of the silane compound include silane coupling agents, polysilazane, siloxane, etc. Specifically, tetramethoxysilane, tetraethoxysilane, glycidoxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, hexamethyl Examples include disilazane.

[Printing layer]
The laminate 1 may include a printed layer. The printed layer can be provided on at least one surface of the base material 11, for example. The printing layer is provided at a position visible from the outside of the laminate 1 for the purpose of displaying information about the contents, identifying the contents, improving concealability, or improving the design of the packaging bag. The printing method and printing ink are not particularly limited, and are appropriately selected from among known printing methods and printing inks, taking into consideration suitability for printing onto a film, design characteristics such as color tone, adhesion, safety as a food container, etc. Ru. As the printing method, for example, a gravure printing method, an offset printing method, a gravure offset printing method, a flexo printing method, an inkjet printing method, etc. can be used. Among them, the gravure printing method can be preferably used from the viewpoint of productivity and high definition of the image.

In order to improve the adhesion of the printed layer, the surface of the layer on which the printed layer is provided may be subjected to various pretreatments such as corona treatment, plasma treatment, flame treatment, etc., or a coat layer such as an easy-to-adhesion layer may be provided.

[Sealant layer 20]
The sealant layer 20 is a layer that provides sealing properties by heat sealing in the laminate 1 . From the viewpoint of suitability for recycling of the laminate 1, the sealant layer 20 is a polyolefin film like the base material 11. In this embodiment, the sealant layer 20 is a resin layer having a single layer structure and mainly made of polypropylene, but is not limited thereto. Sealant layer 20 may include or consist of a polypropylene film.

The polypropylene film may be an acid-modified polypropylene film obtained by graft-modifying polypropylene using an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like. Further, as the polypropylene, polypropylene resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-α-olefin copolymer, etc. can be used.

The polypropylene film constituting the sealant layer 20 is preferably an unstretched polypropylene film from the viewpoint of improving sealing performance by heat sealing.

Various additives such as a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent may be added to the polypropylene film constituting the sealant layer 20.

The thickness of the sealant layer 20 is determined by the mass of the contents, the shape of the packaging bag, etc., but may be approximately 30 to 150 μm, or 50 to 80 μm.

The sealant layer 20 can be formed by a dry lamination method, in which a film-like sealant layer made of polypropylene described above is bonded together with an adhesive such as a one-component curing type or a two-component curing type urethane adhesive; It can be formed by any known lamination method, such as a non-solvent dry lamination method in which the sheets are laminated using a solvent-free adhesive, or an extrusion lamination method in which the above-mentioned polypropylene is heated and melted, extruded into a curtain shape, and laminated together.

Among the above-mentioned forming methods, the dry lamination method is preferred because it has high resistance to retort treatment, especially high-temperature hydrothermal treatment at 120° C. or higher. On the other hand, if the packaging bag is used for processing at a temperature of 85° C. or lower, the lamination method is not particularly limited.

[Adhesive layer 30]
The adhesive layer 30 is a layered member that adheres the barrier layer 10 and the sealant layer 20. As the material of the adhesive included in the adhesive layer 30, for example, polyester-isocyanate resin, urethane resin, polyether resin, etc. can be used. In order to use the packaging bag for retort use, a two-component curing type urethane adhesive having retort resistance can be preferably used. Note that from the viewpoint of environmental considerations, the adhesive does not need to contain 3-glycidyloxypropyltrimethoxysilane (GPTMS). The adhesive layer 30 does not need to contain chlorine. In this case, it is possible to suppress the adhesive forming the adhesive layer 30, the coloring of the recycled resin, etc., and the generation of odor due to heat treatment. From the viewpoint of environmental considerations, the adhesive layer 30 may be formed of a biomass material and may not contain a solvent.

The thickness of the adhesive layer 30 is 0.5 μm or more and 10 μm or less. When the thickness of the adhesive layer 30 is 0.5 μm or more, peeling between the barrier layer 10 and the sealant layer 20 can be suppressed well. When the thickness of the adhesive layer 30 is 10 μm or less, the laminate 1 can be easily made into a monomaterial (details will be described later). The thickness of the adhesive layer 30 may be 1 μm or more, 2 μm or more, 8 μm or less, 6 μm or less, or 5 μm or less.

[Polyolefin content]
The ratio of the total mass of polyolefin (in this embodiment, polypropylene) in the laminate 1 is 90% by mass or more. Thereby, the laminate 1 can be said to be a packaging material made of a single material (monomaterial), and has excellent recyclability. From the viewpoint of further improving recyclability, the content of polyolefin in the laminate 1 may be 92.5% by mass or more, and may be 95% by mass or more, based on the total amount of the laminate 1.

[Heat shrinkage rate of base material 11]
After the base material 11 is exposed to 120° C. for 15 minutes (hereinafter simply referred to as "after heating"), the heat shrinkage rate of the base material 11 in the MD direction determined by the following formula (1) is 1% or more. For example, after heating the base material 11 or the barrier layer 10 including the base material 11 in an oven at 120°C for 15 minutes, the heat shrinkage rate of the base material 11 in the MD direction determined by the following formula (1) is 1% or more. be. From the viewpoint of reducing deformation during bag manufacturing and suppressing peeling between the barrier layer 10 and the sealant layer 20, the heat shrinkage rate in the MD direction is, for example, 12% or less, 11% or less, 10% or less, 9% or less, It is 8% or less, or 7% or less. For example, the heat shrinkage rate of a biaxially stretched polypropylene film is 1%, while the heat shrinkage rate of a PET film is less than 1%.
Thermal contraction rate in MD direction (%) = (MD direction length before heating - MD direction length after heating) / MD direction length before heating × 100... (1)

After the heating, the thermal contraction rate of the base material 11 in the TD direction determined by the following formula (2) is not particularly limited, but is, for example, 1% or more. From the viewpoint of reducing deformation during bag manufacturing and suppressing peeling between the barrier layer 10 and the sealant layer 20, the heat shrinkage rate in the TD direction is, for example, 12% or less, 11% or less, 10% or less, 9% or less, It is 8% or less, or 7% or less.
Thermal contraction rate in TD direction (%) = (TD length before heating - TD length after heating) / TD direction length before heating x 100...(2)

[Hardness of adhesive layer 30]
Based on the heat shrinkage rate of the base material 11 described above, in this embodiment, after the laminate 1 is subjected to retort treatment, the hardness of the adhesive layer 30 is 0.1 MPa or more and less than 0.9 MPa. In this case, the adhesive layer 30 can satisfactorily follow the expansion and contraction of the base material 11 due to heat treatment such as retort treatment and boiling treatment. For this reason, even if the above-mentioned heat treatment is performed on the laminate 1 including the base material 11 having the above-mentioned thermal shrinkage rate, peeling between the barrier layer 10 and the sealant layer 20 is less likely to occur. In addition, cracks may occur in the adhesive layer 30 during cooling after the heat treatment, and damage to the barrier layer 10 (at least one of the adhesive layer 12, the vapor deposited layer 13, and the barrier coat 14) due to the cracks may occur. suppressed. The hardness of the adhesive layer 30 before the retort treatment is not particularly limited, but is, for example, 1.0 MPa or more.

The hardness of the adhesive layer 30 in the laminate 1 is obtained by measuring the hardness of the portion exposed from the sealant layer 20 (exposed portion). Removal of the sealant layer 20 to expose the adhesive layer 30 is performed using, for example, an oblique cutting device. In this embodiment, the hardness of the adhesive layer 30 is obtained by measuring with a nanoindentation method. The nanoindentation method is a measurement method that obtains the mechanical properties of a target object (sample) to be measured by performing a quasi-static indentation test using an indenter. The hardness of a sample such as the adhesive layer 30 is calculated, for example, by the following method. First, fused silica, which will serve as a standard sample, is tested in advance to calibrate the relationship between the contact depth and the projected contact area between the indenter and the sample. Thereafter, the hardness of the sample is calculated by analyzing the unloading curve in the range of 20 to 95% of the maximum load during unloading using the Oliver-Pharr method.

<Packaging bag>
Below, an example of a packaging bag that is a bag product of the laminate 1 will be described with reference to FIG. FIG. 2 is a schematic plan view of an example of a packaging bag. The packaging bag 100 shown in FIG. 2 is formed into a bag shape by, for example, sealing the ends of the laminate 1 which is folded in two so as to sandwich the contents therebetween.

The packaging bag 100 is a three-sided bag having a main body part 101 in which the contents are stored, a seal part 102 located at the end of the main body part 101, and a bent part 103 where the laminate 1 is bent. The shape of the main body portion 101 is not particularly limited, and has a rectangular shape when viewed from a predetermined direction, for example. At least a portion of the outer surface of the main body portion 101 may be printed. For example, the main body portion 101 may contain a specific gas such as nitrogen in addition to the contents. The seal portion 102 is a portion where a portion of the sealant layer 20 included in the laminate 1 and another portion are bonded together. In the seal portion 102, a portion of the sealant layer 20 included in the laminate 1 and another portion are in close contact with each other. The seal portion 102 is formed, for example, by heating and compressing (that is, heat-sealing) a part of the sealant layer 20 and another part of the laminate 1, but is not limited thereto. For example, the seal portion 102 may be formed by cold sealing or the like. In the packaging bag 100, the bent portion 103 constitutes one side of the main body 101, and the seal portion 102 constitutes the remaining three sides of the main body 101. Both ends of the bent portion 103 and the seal portion 102 overlap.

After performing retort treatment on the laminate 1 according to the present embodiment described above, the hardness of the adhesive layer 30 measured by a nanoindentation method is 0.1 MPa or more and less than 0.9 MPa. Thereby, by using the base material 11 having a heat shrinkage rate of 1% or more in the MD direction, even if the base material 11 expands and contracts due to retort treatment, the adhesive layer 30 can follow it well. Therefore, damage to the barrier coat 14 due to the occurrence of cracks in the adhesive layer 30 can be suppressed. Therefore, it is possible to provide a laminate 1 that can exhibit excellent gas barrier properties (especially oxygen permeation prevention performance) even after retort treatment.

In this embodiment, the barrier layer 10 has an adhesion layer 12 and a vapor deposition layer 13 located between the base material 11 and the barrier coat 14, and the adhesion layer 12 is located between the base material 11 and the vapor deposition layer 13. To position. Therefore, the gas barrier properties of the laminate 1 can be improved compared to the case where the barrier layer has only the base material 11 and the barrier coat 14.

In this embodiment, the thickness of the vapor deposition layer 13 may be 5 nm or more and 80 nm or less. In this case, gas barrier properties can be improved while preventing the vapor deposited layer 13 from cracking.

In this embodiment, the thickness of the adhesive layer 30 may be 0.5 μm or more and 10 μm or less. In this case, the laminate 1 can be easily made into a monomaterial while satisfactorily suppressing peeling between the barrier layer 10 and the sealant layer 20.

In this embodiment, each of the base material 11 and the sealant layer 20 is a polyolefin film, and the proportion of the total mass of polyolefin in the laminate 1 may be 90% by mass or more. In this case, monomaterialization is realized.

In this embodiment, the base material 11 is a stretched polypropylene film, and the sealant layer 20 may be a non-stretched polypropylene film. In this case, the laminate 1 has excellent heat resistance against retort processing and the like.

Next, a modification of the above embodiment will be described with reference to FIG. In the following, descriptions that overlap with the above embodiments will be omitted, and portions that are different from the above embodiments will be described. That is, within the technically possible range, the description of the above embodiment may be appropriately used in the modification.

FIG. 3 is a schematic cross-sectional view showing a laminate according to a modified example. As shown in FIG. 3, the laminate 1A includes, in addition to the barrier layer 10, the sealant layer 20, and the adhesive layer 30, an outermost layer 40 that overlaps the barrier layer 10, and a second layer that adheres the outermost layer 40 and the barrier layer 10. It has an adhesive layer 30A. In this modification, the sealant layer 20, the adhesive layer 30, the barrier layer 10, the second adhesive layer 30A, and the outermost layer 40 are laminated in this order. Further, the adhesive layer 30, the base material 11, the adhesive layer 12, the vapor deposition layer 13, the barrier coat 14, the second adhesive layer 30A, and the outermost layer 40 are laminated in this order. Therefore, the adhesive layer 30 adheres the base material 11 and the sealant layer 20, and the second adhesive layer 30A adheres the barrier coat 14 and the outermost layer 40. In this modification, the barrier layer 10 functions as an intermediate layer in the laminate 1A.

[Outermost layer 40]
The outermost layer 40 is a plastic member that functions as the outermost material in the laminate 1A. The outermost layer 40 has the same function and performance as the base material 11. For example, the thickness of the outermost layer 40 is approximately the same as the thickness of the base material 11. From the viewpoint of suitability for recycling of the laminate 1A, the outermost layer 40 is, for example, a polyolefin film. From the viewpoint of heat resistance, the outermost layer 40 may contain or be made of a polypropylene film.

In this modification, after the outermost layer 40 is exposed to 120° C. for 15 minutes, the thermal contraction rate of the outermost layer 40 in the MD direction determined by the above formula (1) is 1% or more. For example, after heating the outermost layer 40 or a laminate of the outermost layer 40 and the barrier layer 10 in an oven at 120°C for 15 minutes, the thermal contraction rate of the outermost layer 40 in the MD direction determined by the above formula (1) is It is 1% or more. The heat shrinkage rate in the MD direction is, for example, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, or 7% or less.

After the heating, the thermal contraction rate of the outermost layer 40 in the TD direction determined by the above formula (2) is not particularly limited, but is, for example, 1% or more and 12% or less.

[Second adhesive layer 30A]
The second adhesive layer 30A is a layered member that adheres the barrier layer 10 and the outermost layer 40. The material of the adhesive included in the second adhesive layer 30A is the same as the material of the adhesive included in the adhesive layer 30. The thickness of the second adhesive layer 30A is similar to the thickness of the adhesive layer 30, and is 0.5 μm or more and 10 μm or less. In this modification, after the laminate 1A is subjected to retort treatment, the hardness of the second adhesive layer 30A is 0.1 MPa or more and less than 0.9 MPa. In this case, the second adhesive layer 30A can satisfactorily follow the expansion and contraction of the outermost layer 40 due to heat treatment such as retort treatment and boil treatment. For this reason, even if the above-mentioned heat treatment is performed on the laminate 1A including the second adhesive layer 30A having the above-mentioned thermal shrinkage rate, peeling between the barrier layer 10 and the outermost layer 40 is unlikely to occur. In addition, cracks occur in the second adhesive layer 30A during cooling after the heat treatment, and damage to the barrier layer 10 (at least one of the adhesive layer 12, the vapor deposited layer 13, and the barrier coat 14) occurs due to the cracks. is suppressed. The hardness of the second adhesive layer 30A before the retort treatment is not particularly limited, but is, for example, 1.0 MPa or more.

Also in the above-described modified example, the same effects as in the above-described embodiment are exhibited. In addition, the outermost layer 40 can protect the barrier layer 10.

The gas barrier laminate and its packaging bag according to one aspect of the present disclosure are as described in, for example, [1] to [10] below, and have been described in detail based on the above embodiment and the above modification.
[1] A barrier layer having a base material on which a barrier coat is provided;
a sealant layer overlapping the barrier layer;
an adhesive layer that adheres the barrier layer and the sealant layer;
A gas barrier laminate comprising:
After the base material is exposed at 120 ° C. for 15 minutes, the heat shrinkage rate of the base material in the MD direction determined by the following formula (1) is 1% or more,
After performing retort treatment on the gas barrier laminate, the hardness of the adhesive layer measured by a nanoindentation method is 0.1 MPa or more and less than 0.9 MPa.
Gas barrier laminate.
Thermal contraction rate in MD direction (%) = (MD direction length before heating - MD direction length after heating) / MD direction length before heating × 100 ... (1)
[2] The barrier layer further includes an anchor coat layer and a vapor deposition layer located between the base material and the barrier coat,
The gas barrier laminate according to [1], wherein the anchor coat layer is located between the base material and the vapor deposition layer.
[3] The gas barrier laminate according to [2], wherein the thickness of the vapor deposited layer is 5 nm or more and 80 nm or less.
[4] The gas barrier laminate according to any one of [1] to [3], wherein the adhesive layer has a hardness of 1.0 MPa or more as measured by a nanoindentation method before the retort treatment.
[5] The gas barrier laminate according to any one of [1] to [4], wherein the adhesive layer has a thickness of 0.5 μm or more and 10 μm or less.
[6] Each of the base material and the sealant layer is a polyolefin film,
The gas barrier laminate according to any one of [1] to [5], wherein the proportion of the total mass of polyolefin in the laminate is 90% by mass or more.
[7] The base material is a stretched polypropylene film,
The gas barrier laminate according to [6], wherein the sealant layer is an unstretched polypropylene film.
[8] an outermost layer overlapping the barrier layer;
further comprising a second adhesive layer that adheres the outermost layer and the barrier layer,
The adhesive layer adheres the base material and the sealant layer,
The gas barrier laminate according to any one of [1] to [7], wherein the second adhesive layer adheres the barrier coat and the outermost layer.
[9] After exposing the outermost layer at 120° C. for 15 minutes, the outermost layer has a heat shrinkage rate in the MD direction of 1% or more as determined by the formula (1),
The gas barrier according to [8], wherein the second adhesive layer has a hardness of 0.1 MPa or more and less than 0.9 MPa, as measured by a nanoindentation method after performing retort treatment on the gas barrier laminate. laminate.
[10] A packaging bag made of the gas barrier laminate according to any one of [1] to [9].

However, one aspect of the present disclosure is not limited to the above embodiment, the above modification, and [1] to [10] above. One aspect of the present disclosure can be further modified without departing from the gist thereof.

In the above embodiment and the above modification, the proportion of the total mass of polypropylene in the laminate may be 90% by mass or more. Therefore, for example, in the laminate according to the above modification, the mass ratio of polypropylene in one of the base material and the outermost layer may be less than 90 mass%. Alternatively, in the laminate, the mass proportion of polypropylene in the barrier layer may be less than 90% by mass.

In the embodiment and the modification described above, the anchor coat layer and the vapor deposition layer are provided on the base material, but the present invention is not limited thereto. For example, a vapor deposition layer may be provided on the sealant layer. In this case, an anchor coat layer may be provided between the sealant layer and the vapor deposition layer. At this time, the sealant layer and the anchor coat layer may be coextruded layers. Alternatively, an anchor coat layer and a vapor deposition layer may be included on the base material, and a vapor deposition layer may be provided on the sealant layer.

The present disclosure will be explained in more detail with reference to the following examples, but the present disclosure is not limited to these examples.

<Base material, outermost layer and sealant layer>
A biaxially oriented polypropylene (OPP) film (manufactured by Mitsui Chemicals Tohcello Co., Ltd., trade name: ME-1, thickness: 20 μm) was prepared as a base material and an outermost layer. Further, as a sealant layer, an unstretched polypropylene (CPP) film (manufactured by Toray Film Kako Co., Ltd., trade name: Torephan ZK93KM, thickness: 60 μm) was prepared.

<Preparation of adhesive layer forming composition>
A mixed solution was produced by mixing and stirring at a ratio of γ-isocyanatepropyltrimethoxysilane:acrylic polyol=1:5. Subsequently, tolylene diisocyanate (TDI) was added to the above mixed solution so that the number of NCO groups in tolylene diisocyanate was equal to the number of OH groups in the acrylic polyol. Then, the mixed solution was diluted with ethyl acetate to a concentration of 2% by mass. Thereby, a composition for forming an adhesion layer (anchor coating agent) was prepared.

<Preparation of coating liquid α for barrier coating>
A coating liquid α was prepared by preparing and mixing 10 g each of the following liquids A, B, and C.
Solution A: 72.1 g of 0.1N hydrochloric acid was added to 17.9 g of tetraethoxysilane (Si(OC ₂ H ₅ ) ₄ ) and 10 g of methanol, and the mixture was stirred for 30 minutes to be hydrolyzed, resulting in a solid content of 5% by mass (SiO ₂ (conversion) hydrolysis solution.
Solution B: 5% by mass water/methanol solution of polyvinyl alcohol (mass ratio of water:methanol is 95:5).
Solution C: 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate was diluted to a solid content of 5% by mass with a mixed solution of water/isopropyl alcohol (mass ratio of water:isopropyl alcohol was 1:1). Hydrolysis solution.

<Preparation of coating liquid β for barrier coating>
First, TEOS, methanol, and 0.1N hydrochloric acid were mixed in a mass ratio of 45/15/40 to obtain a TEOS hydrolyzed solution. This solution, a 5% by mass aqueous solution of polyvinyl alcohol (hereinafter referred to as "PVA"), and 1,3,5-tris(3-methoxysilylpropyl) isocyanurate as a silane coupling agent were mixed in water/IPA (isopropyl alcohol). ) = 1/1 solution diluted to a solid content of 5% by mass (calculated as ^R2Si (OH) ₃ ), and a solution diluted with a 1/1 solution, and a coating liquid β was prepared by mixing three solutions. Coating liquid β was prepared so that the mass ratio of SiO ₂ solid content (converted value) of TEOS, R ² Si(OH) ₃ solid content (converted value) of isocyanurate silane, and PVA solid content was 40/5/55. The solution was prepared as follows.

<Preparation of coating liquid γ for barrier coating>
By blending the following "aqueous polyurethane resin": 40 to 75% by mass, "water-soluble polymer": 10 to 40% by mass, and "silane coupling agent": 5 to 20% by mass, the coating liquid γ was prepared.
Water-based polyurethane resin: Aqueous dispersion of water-based polyurethane resin containing acid group-containing polyurethane resin and polyamine compound, water-based polyurethane dispersion "Takelac (registered trademark) WPB-341" manufactured by Mitsui Chemicals, Inc., solid content 30% .
Water-soluble polymer: polyvinyl alcohol with a degree of saponification of 98 to 99% and a degree of polymerization of 500 (trade name: Poval PVA-105, manufactured by Kuraray Co., Ltd.).
Silane coupling agent: 3-glycidoxypropyltriethoxysilane (trade name: KBE-403, manufactured by Shin-Etsu Chemical Co., Ltd.).

(Example 1)
The composition for forming an adhesive layer was applied to the base material using a bar coat, and the composition for forming an adhesive layer was dried at 50°C. Thereby, an adhesion layer (anchor coat layer) with a thickness of 0.2 μm was formed. Next, a transparent vapor deposition layer (silica vapor deposition layer) made of silicon oxide and having a thickness of 40 nm was formed using a vacuum vapor deposition apparatus using an electron beam heating method.

Next, coating liquid α was applied onto the vapor deposited layer using a bar coat, and the coating liquid α was dried at 60° C. for 1 minute. Thereby, a barrier coat with a thickness of 300 nm was formed on the vapor deposited layer. Through the above steps, a barrier layer including a base material, an adhesive layer, a vapor deposition layer, and a barrier coat was formed.

Next, a two-component adhesive (a) was applied on the barrier coat of the barrier layer to form an adhesive layer with a thickness of 3 μm. Next, a sealant layer was laminated via the adhesive layer by a dry lamination method. In this way, a laminate (gas barrier laminate) having a laminate structure of a base material, an adhesive layer, a vapor deposition layer, a barrier coat, an adhesive layer, and a sealant layer was manufactured. The content of polypropylene in the obtained laminate was 90% by mass or more.

(Examples 2 to 6)
Laminated bodies of Examples 2 to 6 were produced in the same manner as in Example 1, except that two-component adhesives (b) to (f) were used instead of adhesive (a).

(Examples 7 to 12)
The laminates of Examples 7 to 12 were produced in the same manner as Examples 1 to 6, except that coating liquid β was used instead of coating liquid α.

(Examples 13 to 18)
Laminates of Examples 13 to 18 were produced in the same manner as Examples 1 to 6, except that coating liquid γ was used instead of coating liquid α.

(Example 19)
After forming a barrier layer in the same manner as in Example 1, a two-component adhesive (a) was applied on the barrier coat of the barrier layer to form an adhesive layer with a thickness of 3 μm. Next, the outermost layer was laminated with an adhesive layer in between by a dry lamination method. Next, a two-component adhesive (a) was applied onto the base material of the barrier layer to form an adhesive layer with a thickness of 3 μm. Next, a sealant layer was laminated via the adhesive layer by a dry lamination method. In this way, a laminate (gas barrier laminate) having a laminate structure of the outermost layer, the second adhesive layer, the barrier coat, the vapor deposition layer, the adhesive layer, the base material, the adhesive layer, and the sealant layer was manufactured. The content of polypropylene in the obtained laminate was 90% by mass or more.

(Examples 20 to 24)
Laminated bodies of Examples 20 to 24 were produced in the same manner as in Example 19, except that adhesives (b) to (f) were used instead of adhesive (a).

(Examples 25-30)
Laminated bodies of Examples 25 to 30 were produced in the same manner as Examples 19 to 24, except that coating liquid β was used instead of coating liquid α.

(Examples 31 to 36)
Laminated bodies of Examples 31 to 36 were produced in the same manner as Examples 19 to 24, except that coating liquid γ was used instead of coating liquid α.

(Comparative Examples 1 to 3)
Laminates of Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that adhesives (g) to (i) were used instead of adhesive (a).

(Comparative Examples 4 to 6)
Laminates of Comparative Examples 4 to 6 were produced in the same manner as in Example 7, except that adhesives (g) to (i) were used instead of adhesive (a).

(Comparative Examples 7 to 9)
Laminates of Comparative Examples 7 to 9 were produced in the same manner as in Example 13, except that adhesives (g) to (i) were used instead of adhesive (a).

(Comparative Examples 10 to 12)
Laminates of Comparative Examples 10 to 12 were produced in the same manner as in Example 19, except that adhesives (g) to (i) were used instead of adhesive (a).

(Comparative Examples 13 to 15)
Laminates of Comparative Examples 13 to 15 were produced in the same manner as in Example 25, except that adhesives (g) to (i) were used instead of adhesive (a).

(Comparative Examples 16 to 18)
Laminates of Comparative Examples 16 to 18 were produced in the same manner as in Example 31, except that adhesives (g) to (i) were used instead of adhesive (a).

(Comparative Example 19)
A laminate of Comparative Example 19 was produced in the same manner as in Example 1, except that a PET film (thickness: 20 μm) was used as the base material instead of the OPP film.

(Comparative example 20)
A laminate of Comparative Example 20 was produced in the same manner as Comparative Example 1 except that a PET film (thickness: 20 μm) was used instead of the OPP film as the base material.

<Method for measuring heat shrinkage rate of base material>
The thermal shrinkage rate of the base material included in the barrier layer was measured according to the following procedure. The measurement results of the heat shrinkage rates of the base materials in Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1 below. The measurement results of the heat shrinkage rates of the base materials in Examples 7 to 13 and Comparative Examples 4 to 6 are shown in Table 2 below. The measurement results of the heat shrinkage rates of the base materials in Examples 13 to 18 and Comparative Examples 7 to 9 are shown in Table 3 below. The measurement results of the heat shrinkage rates of the base materials in Examples 19 to 24 and Comparative Examples 10 to 12 are shown in Table 4 below. The measurement results of the heat shrinkage rates of the base materials in Examples 25 to 30 and Comparative Examples 12 to 15 are shown in Table 5 below. The measurement results of the heat shrinkage rates of the base materials in Examples 31 to 36 and Comparative Examples 16 to 18 are shown in Table 6 below. The measurement results of the heat shrinkage rates of the base materials in Comparative Examples 19 and 20 are shown in Table 7 below.

(a) As shown in FIG. 4, a measurement sample 500 was obtained by cutting out a base material to be measured into a size of 200 mm x 200 mm.
(b) As shown in FIG. 4, two straight lines L1 and L2 with a length of 120 mm or more parallel to the TD direction of the measurement sample 500 were written with an interval of 100 mm.
(c) As shown in FIG. 4, two straight lines L3 and L4 with a length of 120 mm or more parallel to the MD direction of the measurement sample 500 were written with an interval of 100 mm.
(d) As shown in FIG. 4, scales N1 to N7 were written on the straight line L1 at seven locations at 20 mm intervals. Scales were similarly drawn on the straight lines L2 to L4. At this time, when each of the scales N1 to N7 of the straight line L1 and each of the scales N1 to N7 of the straight line L2 are connected with a straight line, the scales of the straight lines L1 and L2 are set so that the straight line is parallel to the MD direction. The position was adjusted. In addition, when each of the scales N1 to N7 of the straight line L3 and each of the scales N1 to N7 of the straight line L4 are connected with a straight line, the scales of the straight lines L3 and L4 are set so that the straight line is parallel to the TD direction. I adjusted my position.
(e) Measurement sample 500 placed on a Teflon (registered trademark) sheet was placed on a glass plate in an oven heated to a predetermined temperature (150° C. or 160° C.), and heated for 15 minutes. After heating, the measurement sample 500 was taken out of the oven and left at room temperature (25° C.) for 30 minutes.
(f) Measure the linear distance between scale N1 of straight line L1 (the intersection of L1 and N1) and scale N1 of straight line L2 (the intersection of L2 and N1) as the length in the MD direction before and after heating, and use the following formula (1 ) was used to determine the heat shrinkage rate in the MD direction. In the same manner, the heat shrinkage rate in the MD direction at each position of the scales N1 to N7 was determined, and the average value thereof was taken as the heat shrinkage rate in the MD direction of the measurement sample 500.
MD direction heat shrinkage rate (%) = (MD direction length before heating - MD direction length after heating) / MD direction length before heating × 100 ... (1)

<Retort processing>
Using the laminates produced in each of the Examples and Comparative Examples, packaging bags having four sides as seals were produced. The packaging bag was filled with water. Thereafter, retort sterilization treatment was performed at 130°C for 60 minutes.

<Hardness measurement of adhesive layer>
In each of Examples 1 to 18 and Comparative Examples 1 to 9, a laminate that is a part of the packaging bag after retort treatment was cut out. Then, an epoxy adhesive (manufactured by Konishi Co., Ltd., trade name: Bond E Set) was applied onto the base material of the cut out laminate. Then, by attaching the laminate to a glass plate via the epoxy adhesive, a sample having the laminate smoothly fixed to the glass plate was formed. In each of Examples 19 to 36 and Comparative Examples 10 to 18, an epoxy adhesive (manufactured by Konishi Co., Ltd., product name: Bond E set) was applied on the outermost layer of the laminate after retort treatment, A sample was formed.

After the epoxy adhesive had hardened, the sample was placed in an oblique cutting device (manufactured by Daipla Wintes Co., Ltd., trade name: SAICAS DN-GS). Next, a diamond cutting blade having a V-shaped tip was attached to an oblique cutting device, and side cut lines were formed on the surface of the sealant layer at 1 mm width intervals. Next, a diamond knife with a blade width of 1 mm, a rake angle of 20 degrees, and a relief angle of 10 degrees was brought into contact with the surface of the sealant layer under a load of 0.05 N, and then at a horizontal speed of 50 μm/s and a vertical speed of 1 μm/s. The sealant layer was cut diagonally under the following conditions. At this time, first, after the cutting depth reached 55 μm, horizontal cutting was performed by 10 mm. Next, finish cutting was performed at a cutting depth of 1 μm at a horizontal speed of 50 μm/s and a vertical speed of 1 μm/s. The exposed surface after cutting was observed, and the number of finishing cuts was added as necessary until the desired exposed surface of the adhesive layer was obtained. As described above, preparations for measuring the hardness of the adhesive layer after retort treatment (that is, preparations for exposing the adhesive layer) were completed using the nanoindentation method.

Next, Hysitron TI-Premier (trade name) manufactured by Bruker Japan Co., Ltd. was used as a device for measuring the hardness of the adhesive layer by the nanoindentation method. Further, as an indenter, a Berkovich type diamond indenter manufactured by Bruker Japan Co., Ltd. was used. After installing the sample with the adhesive layer exposed on the above device, set the indentation speed: 100 nm/sec, test depth: 125 nm in displacement control mode, and place the indenter on the sample at room temperature (25°C). I pushed it in. Subsequently, after holding the maximum displacement for 2 seconds, the load was unloaded at a speed of 50 nm/second. The surface load was 1 μN, and surface correction was performed using TriboScan software. The measurement point was determined by observing the optical microscope image and measuring the sample surface, that is, the exposed surface of the adhesive layer (when the distance between the sealant layer and the base material layer on the exposed surface is divided into 4 equal parts, the distance from the sealant side is 1/4). Measurement was performed using the nanoindentation method by specifying 30 points at intervals of 30 μm or more. To calculate the hardness of the adhesive layer, first, a standard sample of fused quartz is tested in advance, and the relationship between the contact depth and the projected contact area between the indenter and the sample is calibrated. Then, the unloading curve in the range of 20 to 95% of the maximum load at unloading was analyzed using the Oliver-Pharr method, and the hardness was calculated. The measurement results of the hardness of the adhesive layer in each Example and each Comparative Example are shown in Tables 1 to 7 below.

(Oxygen permeability measurement)
Oxygen permeability (OTR) was measured for the laminate after the retort treatment. The measurement was performed using an oxygen permeability measuring device (OXTRAN 2/20, manufactured by Modern Control) at a temperature of 30° C. and a relative humidity of 70%. The OTR measurement method was based on JIS K-7126, B method (isobaric method), and ASTM D3985-81, and the OTR measurement value was expressed in the unit [cc/m ² ·day · atm]. The OTR measurement results of each Example and each Comparative Example are shown in Tables 1 to 7 below.

In all of Tables 1 to 7, the harder the adhesive layer is, the higher the oxygen permeability measurement results are. However, the absolute value of oxygen permeability varies greatly depending on whether the heat shrinkage rate of the base material is 1% or more. Specifically, when a base material with a heat shrinkage rate of 1% or more is used, as shown in Tables 1 to 6, the oxygen permeability when the hardness of the adhesive layer is 0.9 MPa or more. is higher than the oxygen permeability when the hardness of the adhesive is 0.8 MPa. In addition, when the hardness of the adhesive layer is 0.9 MPa or more, the oxygen permeability is at least 3.5 or more. On the other hand, when a base material with a heat shrinkage rate of less than 1% is used, as shown in Table 7, the oxygen permeability when the hardness of the adhesive layer is 0.9 MPa or more, It can be said that the difference from the oxygen permeability when the hardness of the adhesive is 0.8 MPa is just a margin of error.

In Tables 1 to 3 and Tables 4 to 6, the oxygen permeability of the examples and comparative examples using coating liquid β or coating liquid γ is lower than that of the examples and comparative examples using coating liquid α. It has become. Further, the oxygen permeability of the Examples and Comparative Examples having the outermost layer is lower than that of the Examples and Comparative Examples having no outermost layer.

DESCRIPTION OF SYMBOLS 1, 1A... Laminate, 10... Barrier layer, 11... Base material, 12... Adhesion layer, 13... Vapor deposition layer, 14... Barrier coat, 20... Sealant layer, 30... Adhesive layer, 30A... Second adhesive layer, 40 ...outermost layer.

Claims (10)

a barrier layer having a substrate provided with a barrier coat;
a sealant layer overlapping the barrier layer;
an adhesive layer that adheres the barrier layer and the sealant layer;
A gas barrier laminate comprising:
After the base material is exposed at 120 ° C. for 15 minutes, the heat shrinkage rate of the base material in the MD direction determined by the following formula (1) is 1% or more,
After performing retort treatment on the gas barrier laminate, the hardness of the adhesive layer measured by a nanoindentation method is 0.1 MPa or more and less than 0.9 MPa.
Gas barrier laminate.
Thermal contraction rate in MD direction (%) = (MD direction length before heating - MD direction length after heating) / MD direction length before heating × 100 ... (1) The barrier layer further includes an anchor coat layer and a vapor deposition layer located between the base material and the barrier coat,
The gas barrier laminate according to claim 1, wherein the anchor coat layer is located between the base material and the vapor deposition layer. The gas barrier laminate according to claim 2, wherein the thickness of the vapor deposited layer is 5 nm or more and 80 nm or less. The gas barrier laminate according to any one of claims 1 to 3, wherein the hardness of the adhesive layer measured by a nanoindentation method before the retort treatment is 1.0 MPa or more. The gas barrier laminate according to any one of claims 1 to 3, wherein the adhesive layer has a thickness of 0.5 μm or more and 10 μm or less. Each of the base material and the sealant layer is a polyolefin film,
The gas barrier laminate according to any one of claims 1 to 3, wherein the proportion of the total mass of polyolefin in the laminate is 90% by mass or more. The base material is a stretched polypropylene film,
The gas barrier laminate according to claim 6, wherein the sealant layer is an unstretched polypropylene film. an outermost layer overlapping the barrier layer;
a second adhesive layer that adheres the outermost layer and the barrier layer;
Furthermore,
The adhesive layer adheres the base material and the sealant layer,
The gas barrier laminate according to any one of claims 1 to 3, wherein the second adhesive layer adheres the barrier coat and the outermost layer. After the outermost layer is exposed at 120° C. for 15 minutes, the outermost layer has a heat shrinkage rate in the MD direction of 1% or more as determined by the formula (1),
The gas barrier according to claim 8, wherein the second adhesive layer has a hardness of 0.1 MPa or more and less than 0.9 MPa, as measured by a nanoindentation method after performing retort treatment on the gas barrier laminate. laminate. A packaging bag made of the gas barrier laminate according to any one of claims 1 to 3.

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