Gas barrier laminates and packaging bags

Abstract

To provide a gas barrier laminate which has not only initial water vapor barrier property but also sufficient water vapor barrier property even after having been folded, and uses paper.SOLUTION: A gas barrier laminate has a paper base material, a first resin layer, a vapor-deposited layer and a second resin layer in this order, wherein density of the gas barrier laminate is 0.9 g / cm3 or more and 1.5 g / cm3 or less, and a dimensional change rate in a CD direction of a dimension under an RH environment of 40°C and 90% RH to a dimension under an RH environment of 40°C and 20% of the gas barrier laminate is 0.8% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas barrier laminate and a packaging bag.

Background Art

[0002] In many fields such as food, beverages, pharmaceuticals, and chemicals, packaging materials corresponding to each content are used. The packaging material is required to have a gas barrier property (permeability prevention property) for preventing the permeation of water vapor and the like that cause deterioration of the content.

[0003] In recent years, due to the increasing environmental awareness triggered by problems such as marine plastic waste, the movement to reduce plastics has been on the rise. From the perspective of reducing the use amount of plastic materials, the use of paper instead of plastic materials has been considered in various fields. For example, in Patent Document 1 below, a gas barrier laminate in which a barrier layer is laminated on paper is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since paper has crease retention (also referred to as dead hold property), it has the characteristic of being easy to process. However, according to the study by the present inventors, when a packaging bag (pillow packaging, three-side seal packaging, and gusset packaging) having a sharper crease is used, there is still room for improvement in that cracks occur in the barrier layer and the gas barrier property deteriorates.

[0006] Also, from the perspective of the Law for the Promotion of Effective Use of Resources, it is required to reduce the use amount of plastic materials in the gas barrier laminate.

[0007] Therefore, an object of the present invention is to provide a gas barrier laminate using paper, which has not only an initial water vapor barrier property but also a sufficient water vapor barrier property even after being bent, and a packaging bag containing the same.

Means for Solving the Problems

[0008] The present invention is a gas barrier laminate comprising a paper substrate, a first resin layer, a vapor deposition layer, and a second resin layer in this order, wherein the density of the gas barrier laminate is 0.9 g / cm 3 or more and 1.5 g / cm 3 or less, and the dimensional change rate in the CD direction of the dimension in the 40°C 90%RH environment with respect to the dimension in the 40°C 20%RH environment of the gas barrier laminate is 0.8% or less. A gas barrier laminate is provided.

[0009] In the above gas barrier laminate, the second resin layer may contain a polyolefin having a polar group.

[0010] In the above gas barrier laminate, the thickness of the second resin layer may be 2 μm or more and 10 μm or less.

[0011] In the above gas barrier laminate, the thickness of the vapor deposition layer may be 30 nm or more and 100 nm or less.

[0012] The thickness of the above gas barrier laminate may be 20 μm or more and 100 μm or less.

[0013] The present invention also provides a packaging bag containing the gas barrier laminate according to the present invention.

[0014] The above packaging bag may have a bent portion.

Effects of the Invention

[0015] According to the present invention, it is possible to provide a gas barrier laminate made of paper that has sufficient water vapor barrier properties not only initially but also after being folded, and a packaging bag containing the same. Because the above gas barrier laminate uses paper, it has the crease-retaining properties that are characteristic of paper, and contributes to reducing the amount of plastic material used. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment of the present invention. [Figure 2] This is a perspective view showing a packaging bag according to one embodiment of the present invention. [Modes for carrying out the invention]

[0017] The embodiments of the present invention will be described in detail below, with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments.

[0018] <Gas barrier laminate> Figure 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. The gas barrier laminate 10 according to one embodiment comprises a paper substrate 1, a first resin layer 2, a vapor-deposited layer 3, and a second resin layer 4 in this order.

[0019] The gas barrier laminate 10 has a density of 0.9 g / cm³. 3 More than 1.5g / cm 3 The following conditions are met, and the dimensional change rate in the CD direction of the gas barrier laminate 10 from its dimensions in a 40°C 20%RH environment to its dimensions in a 40°C 90%RH environment (hereinafter sometimes simply referred to as "dimensional change rate") is 0.8% or less. As a result, the gas barrier laminate 10 can have sufficient water vapor barrier properties not only initially, but also after being folded.

[0020] The inventors surmise the following as to why the above effects are achieved: It is thought that the vapor-deposited layer 3 has a considerable number of cracks or defects caused by transport scratches or scratches caused by transfer to the back surface when rolled, and the second resin layer 4 has a considerable number of cracks or defects caused by volume shrinkage of the resin. Furthermore, if the dimensional change rate in the CD direction of the gas barrier laminate 10 from the dimensions in a 40°C 20%RH environment to the dimensions in a 40°C 90%RH environment exceeds 0.8%, these cracks or defects will enlarge, and the water vapor barrier performance will decrease. In particular, cracks or defects in the second resin layer 4 tend to enlarge when bent, and the water vapor barrier performance tends to decrease. In contrast, by keeping the above dimensional change rate at 0.8% or less, it is possible to suppress the enlargement of cracks or defects not only initially but also after bending, and good water vapor barrier performance can be obtained. In addition, by keeping the density of the gas barrier laminate 10 within the above range, the smoothness of the vapor-deposited layer 3 can be improved. If the vapor-deposited layer 3 has irregularities, cracks or defects tend to enlarge when bent, using these irregularities as starting points. However, by keeping the density of the gas barrier laminate 10 within the above range, this problem can be improved, and good water vapor barrier properties can be obtained not only initially but also after bending.

[0021] The dimensional change rate in the CD direction of the gas barrier laminate 10, compared to its dimensions under a 40°C 20%RH environment, was measured using the following method. First, the gas barrier laminate was cut to a predetermined size to serve as a sample for measurement. This sample was left in a constant temperature and humidity chamber at 40°C 20%RH for three days, and then the length of the sample in the CD direction was measured inside the chamber. Subsequently, the same sample was left in a constant temperature and humidity chamber at 40°C 90%RH for three days, and then the length of the sample in the CD direction was measured inside the chamber. The dimensional change rate (%) in the CD direction of the sample, compared to its dimensions under a 40°C 20%RH environment, was calculated using the following formula. (Length at 40°C 90%RH - Length at 40°C 20%RH) / Length at 40°C 20%RH × 100

[0022] The dimensional change rate in the CD direction of the dimensions of the gas barrier laminate 10 in a 40°C 90% RH environment with respect to the dimensions in a 40°C 20% RH environment needs to be 0.8% or less. However, from the perspective of making the water vapor barrier property better both initially and after bending, it may be 0.7% or less, or may be 0.65% or less. Also, the lower limit of the dimensional change rate in the CD direction of the dimensions of the gas barrier laminate 10 in a 40°C 90% RH environment with respect to the dimensions in a 40°C 20% RH environment is not particularly limited, and it may be 0% or more, or may be 0.1% or more. The dimensional change rate of the gas barrier laminate 10 can be adjusted, for example, by changing the dimensional change rate in the CD direction of the dimensions of the paper base material in a 40°C 90% RH environment with respect to the dimensions in a 40°C 20% RH environment, the density of the gas barrier laminate 10, the density of the paper base material, the thickness of the coating layer described later, the content of the filler in the coating layer, the basis weight of the paper base material, the fiber length and fiber diameter of the paper, and the amount of polar groups in the first and second resin layers.

[0023] The density of the gas barrier laminate 10 is a value measured in accordance with JIS P8118. The density of the gas barrier laminate 10 is 3 1.5 g / cm 3 or less, but from the perspective of making the water vapor barrier property better both initially and after bending, it may be 0.95 g / cm 3 or more, may be 1.0 g / cm 3 or more, or may be 1.1 g / cm 3 or more. Also, the density of the gas barrier laminate 10 may be 1.4 g / cm 3 or less, may be 1.3 g / cm 3 or less, or may be 1.2 g / cm 3 or less.

[0024] The thickness of the gas barrier laminate 10 may be 20 to 100 μm, may be 30 to 80 μm, or may be 40 to 60 μm. When the thickness of the gas barrier laminate 10 is within the above range, the gas barrier laminate 10 can obtain a better water vapor barrier property not only initially but also after being bent.

[0025] [Paper base material] The paper substrate 1 is not particularly limited, but the density of the gas barrier laminate 10 is 0.9 g / cm³. 3 More than 1.5g / cm 3 It is preferable to select and use a material that can meet the following requirements and has a dimensional change rate of 0.8% or less. The paper base material 1 may be paper mainly composed of plant-derived pulp. Specific examples of the paper base material 1 include fine paper, special fine paper, coated paper, art paper, cast coated paper, imitation paper, kraft paper, and glassine paper. The basis weight of the paper base material 1 is 20 to 500 g / m². 2 , or 30-100g / m 2 That's fine.

[0026] The paper substrate 1 may have a coating layer on at least the side in contact with the first resin layer 2. If the paper substrate 1 has a coating layer, the paper substrate 1 may have at least a paper layer and a coating layer. The coating layer may be provided on both surfaces of the paper substrate 1. By providing a coating layer, it is possible to prevent the first resin layer 2 from seeping into the paper, and it can also act as a sealer to fill in the irregularities of the paper, allowing the first resin layer 2 to be formed uniformly without defects. For example, the coating layer may use various copolymers such as styrene-butadiene, styrene-acrylic, and ethylene-vinyl acetate as binder resins, polyvinyl alcohol resins, cellulose resins, paraffin (wax), etc., and may contain clay, kaolin, calcium carbonate, talc, mica, etc. as fillers. The coating layer may be a clay coating layer containing at least clay as a filler.

[0027] If the paper substrate 1 is provided with a coating layer, the thickness of the coating layer may be 1.5 μm or more and 15 μm or less. The thickness of the coating layer may be 1.8 μm or more, 3 μm or more, 5 μm or more, or 6 μm or more. The thickness of the coating layer may be 12 μm or less or 10 μm or less. When the thickness of the coating layer is within the above range, the gas barrier laminate 10 can obtain better water vapor barrier properties not only initially but also after being folded.

[0028] The thickness of the paper substrate 1 may be 20 to 100 μm, 30 to 80 μm, or 40 to 60 μm. When the thickness of the paper substrate 1 is within the above range, the gas barrier laminate 10 can obtain better water vapor barrier properties not only initially but also after being folded.

[0029] The ratio of the thickness of the coating layer to the thickness of the paper substrate 1 may be 3-25% or 5-20%. When this ratio is within the above range, the gas barrier laminate 10 can obtain better water vapor barrier properties not only initially but also after being folded.

[0030] The dimensional change rate in the CD direction of the paper substrate 1, relative to its dimensions under a 40°C 90%RH environment, may be 0.8% or less, 0.7% or less, or 0.6% or less. The dimensional change rate of the gas barrier laminate 10 is greatly influenced by the dimensional change rate of the paper substrate 1. Therefore, by setting the dimensional change rate of the paper substrate 1 to 0.8% or less, it is easier to adjust the dimensional change rate of the gas barrier laminate 10 to 0.8% or less. Furthermore, the lower limit of the dimensional change rate in the CD direction of the paper substrate 1, relative to its dimensions under a 40°C 90%RH environment, is not particularly limited, but may be 0% or more, or 0.1% or more. The dimensional change rate of the paper substrate 1 can be measured in the same way as the dimensional change rate of the gas barrier laminate.

[0031] The density of paper substrate 1 is 0.9 g / cm³. 3 More than 1.5g / cm 3 The following is acceptable. The density of the gas barrier laminate 10 is greatly affected by the density of the paper substrate 1. Therefore, the density of the paper substrate 1 is 0.9 g / cm³. 3 More than 1.5g / cm 3 By doing the following, the density of the gas barrier laminate 10 can be set to 0.9 g / cm³. 3 More than 1.5g / cm 3 The following can be easily adjusted. Also, the density of paper substrate 1 is 0.95 g / cm³. 3 It may be greater than or equal to 1.0 g / cm³.3 It may be greater than or equal to 1.1 g / cm³. 3 The above may also be acceptable. Furthermore, the density of the paper substrate 1 is 1.4 g / cm³. 3 It may also be less than 1.3 g / cm³. 3 It may also be less than 1.2 g / cm³. 3 The following is also acceptable: The density of the paper substrate 1 is 0.9 g / cm³. 3 By doing so, the smoothness of the paper substrate 1 can be improved, and thereby the smoothness of the vapor-deposited layer 3 can be improved. As a result, the gas barrier laminate 10 can obtain better water vapor barrier properties not only initially but also after being folded. Furthermore, the density of the paper substrate 1 can be increased to 1.5 g / cm³. 3 By doing the following, appropriate voids can be formed between the fibers of the paper substrate 1, thereby easing the stress applied to the paper substrate 1 when folded. As a result, it is possible to suppress the enlargement of cracks or defects in the vapor-deposited layer 3 when folded, and the gas barrier laminate 10 can obtain better water vapor barrier properties not only initially but also after being folded. The density of the paper substrate 1 can be measured in the same way as the density of the gas barrier laminate.

[0032] The weight of the paper is preferably 50% or more by mass of the entire gas barrier laminate, more preferably 70% or more by mass, and even more preferably 80% or more by mass. If the weight of the paper is 50% or more by mass of the entire gas barrier laminate, the amount of plastic material used can be sufficiently reduced, the entire gas barrier laminate can be said to be made of paper, and it has excellent recyclability.

[0033] [First resin layer] The first resin layer 2 is provided on the surface of the paper substrate 1 to improve adhesion between the paper substrate 1 and the vapor-deposited layer 3 (described later) and to improve the gas barrier properties of the gas barrier laminate. The first resin layer is also called the anchor coat layer. The first resin layer 2 may contain a polyolefin having polar groups. By containing a polyolefin having polar groups, the first resin layer 2 has excellent flexibility, which can suppress cracking of the vapor-deposited layer (described later) after bending (folding), and can improve adhesion between the first resin layer and the vapor-deposited layer. Furthermore, by containing a polyolefin having polar groups, it is possible to form a dense film due to the crystallinity of the polyolefin, and water vapor barrier properties are exhibited. Water vapor barrier properties are exhibited due to the crystallinity of the polyolefin, and adhesion to the vapor-deposited layer is exhibited due to the presence of polar groups.

[0034] A polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid ester.

[0035] As the polyolefin having polar groups, copolymers of ethylene or propylene with unsaturated carboxylic acids (unsaturated compounds having carboxyl groups such as acrylic acid, methacrylic acid, and maleic anhydride), unsaturated carboxylic acid esters, and salts obtained by neutralizing carboxylic acids with basic compounds may be used. In addition, copolymers with vinyl acetate, epoxy compounds, chlorine compounds, urethane compounds, polyamide compounds, etc., may also be used.

[0036] Examples of polyolefins having polar groups include copolymers of acrylic acid esters and maleic anhydride, ethylene-vinyl acetate copolymers, and ethylene-glycidyl methacrylate copolymers.

[0037] The first resin layer 2 may contain other components in addition to the polyolefin having the polar group described above. Examples of other components include polyolefins other than the polyolefin having the polar group described above, silane coupling agents, organic titanates, polyacrylics, polyesters, polyurethanes, polycarbonates, polyureas, polyamides, polyimides, melamines, phenols, and the like.

[0038] The content of the polyolefin having the polar group in the first resin layer 2 may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0039] The thickness of the first resin layer 2 may be, for example, 0.5 μm or more, 1 μm or more, 2 μm or more, 20 μm or less, 10 μm or less, or 5 μm or less. If the thickness of the first resin layer 2 is 0.5 μm or more, the irregularities of the paper substrate described above can be efficiently filled, and the vapor-deposited layer described later can be uniformly laminated. Also, if the thickness of the first resin layer 2 is 20 μm or less, the vapor-deposited layer can be uniformly laminated while keeping costs down.

[0040] Examples of solvents included in the coating solution for the first resin layer 2 include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used individually or in combination of two or more. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of properties. Furthermore, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred from the viewpoint of the environment.

[0041] The first resin layer 2 can be obtained by applying a coating solution containing the above-mentioned polyolefin having polar groups and a solvent onto a paper substrate and drying it. From the viewpoint of preventing blocking, the polyolefin having polar groups in the coating solution should have a larger particle size so that the contact area is small. Although not particularly limited, the particle size may be 1 nm or larger, 0.1 μm or larger, 1 μm or less, 0.7 μm or less, or 0.5 μm or less.

[0042] [Vapour-deposited layer] The vapor-deposited layer 3 is a layer on which a metal or inorganic compound has been deposited. The vapor-deposited layer may be one obtained by depositing aluminum, or aluminum oxide (AlO x ), silicon dioxide (SiO₂) x It may also include ) etc.

[0043] The thickness of the vapor-deposited layer 3 can be set appropriately depending on the application, but is preferably 10 to 300 nm, and more preferably 30 to 100 nm. Setting the thickness of the vapor-deposited layer 3 to 10 nm or more makes it easier to ensure sufficient continuity of the vapor-deposited layer 3, and setting it to 300 nm or less makes it easier to suppress the occurrence of curl and cracks, thereby achieving sufficient gas barrier performance and flexibility. Furthermore, setting the thickness of the vapor-deposited layer to 30 nm or more and 100 nm or less makes the vapor-deposited layer less prone to cracking, and sufficient water vapor barrier properties can be obtained even after bending.

[0044] The deposited layer 3 is preferably deposited by a vacuum deposition method from the viewpoint of water vapor and oxygen gas barrier performance and film uniformity. Known deposition methods include vacuum deposition, sputtering, and chemical vapor deposition (CVD), but vacuum deposition is preferred because it has a fast deposition rate and high productivity. Among vacuum deposition methods, electron beam heating is particularly effective because the deposition rate can be easily controlled by the irradiation area and electron beam current, and the heating and cooling of the deposition material can be performed in a short time.

[0045] [Second resin layer] The second resin layer 4 is provided on the surface of the vapor-deposited layer 3, in contact with the vapor-deposited layer 3. The second resin layer is also called the overcoat layer. The second resin layer may contain a polyolefin having polar groups.

[0046] A polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid ester.

[0047] As the polyolefin having polar groups, copolymers of ethylene or propylene with unsaturated carboxylic acids (unsaturated compounds having carboxyl groups such as acrylic acid and methacrylic acid), unsaturated carboxylic acid esters, and salts obtained by neutralizing carboxylic acids with basic compounds may be used. In addition, copolymers with vinyl acetate, epoxy compounds, chlorine compounds, urethane compounds, polyamide compounds, etc., may also be used.

[0048] Examples of polyolefins having polar groups include copolymers of acrylic acid esters and maleic anhydride, ethylene-vinyl acetate copolymers, and ethylene-glycidyl methacrylate copolymers.

[0049] By containing a polyolefin with polar groups, the second resin layer 4 exhibits excellent flexibility, suppressing cracking of the vapor-deposited layer after bending (folding), and also exhibits excellent adhesion to the vapor-deposited layer. Furthermore, the inclusion of the aforementioned polyolefin with polar groups enables the formation of a dense film due to the crystalline nature of the polyolefin, resulting in water vapor barrier properties. The presence of polar groups also contributes to adhesion to the vapor-deposited layer. Moreover, because the second resin layer 4 contains the polyolefin with polar groups, it can also function as a heat-seal layer, eliminating the need for a separate heat-seal layer.

[0050] The second resin layer 4 may contain other components in addition to the polyolefin having the polar group described above. Examples of other components include silane coupling agents, organic titanates, polyacrylics, polyesters, polyurethanes, polycarbonates, polyureas, polyamides, polyolefin emulsions, polyimides, melamines, phenols, and the like.

[0051] The content of the polyolefin having polar groups in the second resin layer 4 may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0052] The thickness of the second resin layer 4 may be, for example, 0.05 μm or more, 0.5 μm or more, 1 μm or more, 2 μm or more, 20 μm or less, 10 μm or less, or 5 μm or less. If the thickness of the second resin layer 4 is 0.05 μm or more, it can fully perform the role of a heat seal layer as described above. If the thickness of the second resin layer 4 is 20 μm or less, it can fully exhibit adhesion and barrier properties with the vapor-deposited layer while keeping costs down. Furthermore, by setting the thickness of the second resin layer 4 to 2 μm or more and 10 μm or less, the vapor-deposited layer becomes less prone to cracking, and sufficient water vapor barrier properties can be obtained even after bending.

[0053] In the gas barrier laminate 10, when the second resin layer 4 contains a polyolefin having polar groups, the thickness of the second resin layer 4 is set to 2 μm or more and 10 μm or less, and the thickness of the vapor-deposited layer 3 is set to 30 nm or more and 100 nm or less, the vapor-deposited layer 3 becomes less prone to cracking, and the effect of obtaining sufficient water vapor barrier properties even after bending is particularly remarkable.

[0054] Examples of solvents included in the coating solution for the second resin layer 4 include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used individually or in combination of two or more. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of properties. Furthermore, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred from the viewpoint of environmental impact.

[0055] The second resin layer 4 can be obtained by applying a coating solution containing the above-mentioned polyolefin having polar groups and a solvent onto the vapor-deposited layer and drying it. The melting point of the polyolefin having polar groups in the coating solution is preferably 70 to 160°C, and more preferably 80 to 120°C. A lower melting point of the polyolefin having polar groups has the advantage of lowering the start-up temperature during heat sealing. A higher melting point of the polyolefin having polar groups increases the risk of blocking in high-temperature environments. From the viewpoint of preventing blocking, it is preferable to have a larger particle size so that the contact area is smaller. Although not particularly limited, the particle size may be 1 nm or larger, 0.1 μm or larger, 1 μm or less, 0.7 μm or less, or 0.5 μm or less.

[0056] The polar group-containing polyolefins contained in the first resin layer 2 and the second resin layer 4 may be of the same type or different types, but considering ease of manufacture and other factors, it is preferable that they be of the same type.

[0057] <Packaging bag> Figure 2 is a perspective view showing a gusset bag 20 made of a gas barrier laminate 10. The packaging bag is manufactured by sealing the opening at the top of the gusset bag 20. The gusset bag 20 has folded sections (folded sections B1, B2) where the gas barrier laminate 10 is folded. Folded section B1 is where the gas barrier laminate 10 is valley-folded when viewed from the innermost layer side, while folded section B2 is where the gas barrier laminate 10 is mountain-folded when viewed from the innermost layer side.

[0058] The packaging bag may be formed by folding a single gas barrier laminate in half so that the second resin layers 4 face each other, then folding it appropriately to the desired shape and heat-sealing it, or by stacking two gas barrier laminates so that the second resin layers 4 face each other, and then heat-sealing them to form a bag.

[0059] In the packaging bag according to this embodiment, the heat seal strength may be 2N or more, or 4N or more. There is no particular upper limit to the heat seal strength, but it may be, for example, 10N or less.

[0060] The packaging bag can contain contents such as food and pharmaceuticals. It is particularly suitable for containing confectionery and similar items. The packaging bag according to this embodiment can maintain high gas barrier properties even when it has a folded portion.

[0061] In this embodiment, a gusseted bag was given as an example of a packaging bag, but the gas barrier laminate according to this embodiment may also be used to manufacture, for example, pillow bags, three-sided sealed bags, or standing pouches. [Examples]

[0062] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0063] <Fabrication of gas barrier laminates> (Example 1) Paper base material (manufactured by Fuji Kako Co., Ltd., product name: Toku Cormorant, thickness 52 μm, basis weight 52.3 g / m²) 2 A polyolefin aqueous dispersion containing a carboxyl group salt is applied to the surface (with a clay coat layer) using a bar coater (wet application rate 15g / m²). 2 A solid content concentration of 20% by mass was adjusted and dried in an oven to form a first resin layer. Subsequently, Al deposition was performed on the first resin layer by vacuum deposition to form an Al deposition layer. The thickness of the Al deposition layer was 50 nm. After that, an aqueous dispersion of polyolefin containing a carboxyl group salt was coated onto the deposition layer with a bar coater and dried in an oven to form a second resin layer, thereby obtaining a gas barrier laminate. The thickness of the second resin layer was 3 μm.

[0064] (Example 2) As the paper base material, we used Tokukomo S (product name, thickness 49 μm, basis weight 52.3 g / m²) manufactured by Fuji Kako Co., Ltd. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0065] (Example 3) As the paper base material, we used Ryuo Coat (product name, thickness 45 μm, basis weight 55 g / m²) manufactured by Daio Paper Corporation. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0066] (Example 4) As the paper base material, coated packaging paper manufactured by Xianhe Co., Ltd. (thickness 41 μm, basis weight 50 g / m²) is used. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0067] (Example 5) As a paper base material, we use coated packaging paper manufactured by Senkaku Co., Ltd. (thickness 51 μm, basis weight 60 g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0068] (Example 6) The paper base material is coated packaging paper manufactured by Senkaku Co., Ltd. (thickness 51 μm, basis weight 60 g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used and the vapor-deposited layer was a silica vapor-deposited layer formed by vacuum deposition.

[0069] (Example 7) The paper base material is coated packaging paper manufactured by Senkaku Co., Ltd. (thickness 51 μm, basis weight 60 g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used and the vapor deposition layer was an alumina vapor deposition layer formed by vacuum deposition.

[0070] (Example 8) The paper base material is coated packaging paper manufactured by Senkaku Co., Ltd. (thickness 51 μm, basis weight 60 g / m²). 2 Using a clay coat layer, the first resin layer is coated with a coating solution containing polyvinyl alcohol resin with a degree of polymerization of 500 using a bar coater (wet application amount 30g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that the solid content was reduced to 10% by mass and dried in an oven.

[0071] (Example 9) The paper base material is Ryuo Coat (product name, thickness 45 μm, basis weight 55 g / m²) manufactured by Daio Paper Corporation. 2 Using a clay coat layer, the first resin layer is coated with a coating solution containing polyvinyl alcohol resin with a degree of polymerization of 500 using a bar coater (wet application amount 30g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that the solid content was reduced to 10% by mass and dried in an oven.

[0072] (Comparative Example 1) As the paper base material, we use Glassine N (product name, thickness 26 μm, basis weight 30.5 g / m²) manufactured by Nippon Paper Industries Co., Ltd. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0073] (Comparative Example 2) As the paper base material, we used APP's Enza HS Rapping Paper (product name, thickness 77μm, basis weight 60g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0074] (Comparative Example 3) As the paper substrate, we used Solide Lucent (product name, thickness 35 μm, basis weight 40 g / m²) manufactured by UPM. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0075] (Comparative Example 4) As the paper substrate, we used Solide Strong (product name, thickness 67 μm, basis weight 60 g / m²) manufactured by UPM. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0076] (Comparative Example 5) As the paper substrate, we used Brilliant Express (product name, thickness 34 μm, basis weight 40 g / m²) manufactured by UPM. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0077] (Comparative Example 6) As the paper substrate, we used Brilliant Duo (product name, thickness 51 μm, basis weight 62 g / m²) manufactured by UPM. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0078] (Comparative Example 7) As the paper substrate, we used Brilliant (product name, thickness 51 μm, basis weight 60 g / m²) manufactured by UPM. 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that a clay coat layer was used.

[0079] (Comparative Example 8) As the paper substrate, we used Solide Lucent (product name, thickness 35 μm, basis weight 40 g / m²) manufactured by UPM. 2 Using a clay coat-less design, the first resin layer is coated with a coating solution containing polyvinyl alcohol resin with a degree of polymerization of 500 using a bar coater (wet coating amount: 30 g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that the solid content was reduced to 10% by mass and dried in an oven.

[0080] (Comparative Example 9) As the paper substrate, we used Brilliant (51 μm thickness, 60 g / m² basis weight) manufactured by UPM. 2 Using a clay coat layer, the first resin layer is coated with a coating solution containing polyvinyl alcohol resin with a degree of polymerization of 500 using a bar coater (wet application amount 30g / m²). 2 A gas barrier laminate was obtained by the same procedure as in Example 1, except that the solid content was reduced to 10% by mass and dried in an oven.

[0081] <Density Measurement> The density of the gas barrier laminates in the examples and comparative examples, and the paper substrates used in the examples and comparative examples, were measured in accordance with JIS P8118. The results are shown in Tables 1 and 2.

[0082] <Measurement of dimensional change rate> The gas barrier laminates from the examples and comparative examples, and the paper substrates used in the examples and comparative examples, were cut to a size of 150 mm in length and 20 mm in width in the CD direction, respectively, to be used as measurement samples. These samples were left in a constant temperature and humidity chamber at 40°C and 20%RH for 3 days, and then the length of the sample in the CD direction was measured using a glass scale in the chamber. Subsequently, the same samples were left in a constant temperature and humidity chamber at 40°C and 90%RH for 3 days, and then the length of the sample in the CD direction was measured using a glass scale in the chamber. The dimensional change rate (%) in the CD direction of the sample under the 40°C and 90%RH environment compared to the 40°C and 20%RH environment was calculated using the following formula. The results are shown in Tables 1 and 2. (Length at 40°C 90%RH - Length at 40°C 20%RH) / Length at 40°C 20%RH × 100

[0083] <Measurement of water vapor transmission rate> The water vapor permeability of the gas barrier laminates in the examples and comparative examples was measured using the MOCON method. The measurement conditions were a temperature of 40°C and a relative humidity of 90%. A 1500g roller was rolled at a speed of 300mm / min to create folds in the gas barrier laminate parallel to the MD direction, and the water vapor permeability of the gas barrier laminate after unfolding was measured in the same manner. In Tables 1 and 2, "inward fold" refers to the gas barrier laminate after a mountain fold as viewed from the paper substrate side, and "outward fold" refers to the gas barrier laminate after a valley fold as viewed from the paper substrate side. The results are shown in Tables 1 and 2 in units [g / m²]. 2 It was written as "day".

[0084] [Table 1]

[0085] [Table 2]

[0086] As shown in Tables 1 and 2, the gas barrier laminates of the examples exhibit a water vapor transmission rate of 10 g / m² not only initially but also after bending. 2 The results were good, below 1 day. According to the gas barrier laminate of the present invention, even when a packaging bag with a folded portion is formed, the deterioration of the contents can be suppressed over a long period of time. [Explanation of symbols]

[0087] 1...Paper substrate, 2...First resin layer, 3...Vaporized layer, 4...Second resin layer, 10...Gas barrier laminate, 20...Gusseted bag, B1, B2...Folded section.

Claims

1. A gas barrier laminate comprising a paper substrate, a first resin layer, a vapor-deposited layer, and a second resin layer in this order, The paper substrate is provided with a coating layer on the side that is in contact with the first resin layer. The coating layer contains at least one binder resin selected from the group consisting of styrene-butadiene copolymers, styrene-acrylic copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol resins, cellulose resins, and paraffin, and at least one filler selected from the group consisting of clay, kaolin, calcium carbonate, talc, and mica. The density of the aforementioned paper substrate is 0.9 g / cm³ or more and 1.5 g / cm³ or less. The second resin layer comprises a polyolefin having polar groups, The density of the gas barrier laminate is 0.9 g / cm³. ３ 1.5g / cm or more ３ The following: A gas barrier laminate in which the dimensional change rate in the CD direction of the dimensions under a 40°C 90% RH environment is 0.8% or less compared to the dimensions under a 40°C 20% RH environment.

2. The gas barrier laminate according to claim 1, wherein the thickness of the second resin layer is 2 μm or more and 10 μm or less.

3. The gas barrier laminate according to claim 1 or 2, wherein the thickness of the deposited layer is 30 nm or more and 100 nm or less.

4. The gas barrier laminate according to any one of claims 1 to 3, wherein the thickness of the gas barrier laminate is 20 μm or more and 100 μm or less.

5. A packaging bag comprising a gas barrier laminate according to any one of claims 1 to 4.

6. The packaging bag according to claim 5, having a foldable portion.

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