WO2023062963A1

WO2023062963A1 - Laminate, packaging material, and packaged article

Info

Publication number: WO2023062963A1
Application number: PCT/JP2022/033186
Authority: WO
Inventors: 亮太田中; 俊一塩川; 晴香大森; 健太大沢; 陽香合田
Original assignee: 凸版印刷株式会社
Priority date: 2021-10-11
Filing date: 2022-09-02
Publication date: 2023-04-20

Abstract

Provided is a laminate mainly comprising polyethylene and having excellent heat resistance or easy-to-tear properties. This laminate (10A) comprises a base layer (2), an adhesive layer (6), and a sealant layer (7) in the stated order. The base layer (2) and the sealant layer (7) contain polyethylene. The birefringence ΔN of the base layer (2) as measured by a parallel Nicols rotation method is in the range of 0.01-0.1.

Description

Laminates, packages and packaged articles

The present invention relates to laminates, packages and packaged goods.

Various characteristics are required for the packaging materials used for packaging bags, etc., depending on the application. Examples of required properties include heat resistance, transparency, strength, gas barrier properties, suitability for bag making, suitability for printing, suitability for transportation, etc., which are required as packaging materials. In addition, packaging materials used for packaging bags and the like are required to have improved tearability so that the packaging bags can be easily opened by hand. In order to sufficiently satisfy such various performances, conventionally, it has been common practice to combine a plurality of types of synthetic resin films having different properties.

For example, a resin film made of polyethylene cannot be used alone as a base material for packaging materials because it is inferior in terms of strength and heat resistance. there is

In recent years, along with the growing demand for building a recycling-oriented society, packaging materials with high recyclability are in demand. In general, it is considered that packaging materials with a main resin content of 90% by mass or more are highly recyclable. However, conventional packaging materials are composed of different types of resin materials as described above, and it is difficult to separate each resin material after use, so it was not possible to recycle each material. Therefore, even if a package made of conventional packaging materials is recovered, it can only be recovered and used as heat by burning it. is the current situation.

When packaging materials made of polyethylene resin are used to achieve high recyclability, there are specific problems such as the following. That is, in the bag-making process for forming a packaging bag, the sealant layers of the laminate are usually put together and heat-sealed (heat-sealed) by applying pressure to a high-temperature jig from the outer surface side of the base material layer of the laminate and sandwiching them. There is a process. The jig of the heat-sealing machine is at a high temperature, and the outer surface side of the base material layer, which is in direct contact with the jig, is exposed to high temperature. When the base layer made of polyethylene resin, which has poor heat resistance, is exposed to heat, the heat-sealed portion is damaged by heat, resulting in appearance defects such as heat shrinkage and distortion, and adhesion of the resin to jigs. Problems may occur. In order to avoid this problem, if the bag-making conditions are narrowed by slowing down the bag-making speed or adjusting the bag-making temperature (heat sealing temperature) in order to reduce heat damage, productivity will deteriorate. .

Patent Document 1 proposes a technique for making the layer structure of the packaging film as simple as possible from the viewpoint of recycling. That is, focusing on the fact that polyethylene single-layer films have problems with blocking resistance and unsealability (ease of opening) when used as a package, in order to improve this, on the polyethylene-containing base layer, A packaging film has been proposed which is provided with a resin-containing coating layer whose glass transition temperature satisfies specific conditions on a polyethylene-containing substrate.

However, the fact that polyethylene resin is inferior in heat resistance is not considered, and it does not solve the above heat resistance problems in packaging materials containing polyethylene resin as the main material.

Japanese Patent Application Laid-Open No. 2020-196791

An object of the present invention is to provide a laminate that is mainly made of polyethylene and has excellent heat resistance and tear resistance.

According to one aspect of the present invention, a substrate layer, an adhesive layer and a sealant layer are provided in this order, the substrate layer and the sealant layer contain polyethylene, and the substrate layer is formed by a parallel Nicols rotation method. Laminates having a measured birefringence ΔN in the range of 0.01 to 0.1 are provided.

According to another aspect of the present invention, there is provided the laminate according to the above aspect, wherein the base layer has the birefringence ΔN within the range of 0.01 to 0.052.

According to still another aspect of the present invention, there is provided a laminate according to any one of the above aspects, further comprising an intermediate layer interposed between the base material layer and the sealant layer and containing polyethylene.

According to still another aspect of the present invention, there is provided the laminate according to the above aspect, wherein the intermediate layer has a birefringence ΔN measured by a parallel Nicols rotation method within a range of 0 to 0.01.

According to still another aspect of the present invention, there is provided the laminate according to the above aspect, wherein the intermediate layer has a birefringence ΔN measured by a parallel Nicols rotation method within a range of 0.01 to 0.1.

According to still another aspect of the present invention, there is provided the laminate according to the above aspect, wherein the intermediate layer has the birefringence ΔN within the range of 0.01 to 0.052.

According to still another aspect of the present invention, there is provided a laminate according to any of the above aspects, further comprising a protective layer as an outermost layer facing the sealant layer with the base layer interposed therebetween.

According to still another aspect of the present invention, there is provided the laminate according to the aspect above, wherein the protective layer is made of a thermosetting resin.

According to still another aspect of the present invention, there is provided a laminate according to any of the aspects above, wherein the substrate layer is a biaxially stretched film.

According to still another aspect of the present invention, there is provided a laminate according to any of the aspects above, wherein the substrate layer is a uniaxially stretched film.

According to still another aspect of the present invention, there is provided a laminate according to any one of the aspects above, further comprising a gas barrier layer interposed between the base material layer and the sealant layer.

According to still another aspect of the present invention, there is provided a laminate according to any of the aspects above, wherein the adhesive layer has gas barrier properties.

According to still another aspect of the present invention, there is provided a laminate according to any of the aspects above, wherein the sealant layer is white.

According to still another aspect of the present invention, there is provided a laminate according to any one of the above aspects, in which the ratio of polyethylene is 90% by mass or more.

According to still another aspect of the present invention, there is provided a package containing the laminate according to any one of the above aspects.

According to still another aspect of the present invention, there is provided a package according to the above aspect, which is a standing pouch.

According to still another aspect of the present invention, there is provided a packaged article including a package according to any one of the above aspects and contents housed therein.

According to the present invention, a laminate that is mainly made of polyethylene and has excellent heat resistance and tear resistance is provided.

FIG. 1 is a cross-sectional view schematically showing a laminate according to a first embodiment of the invention. FIG. 2 is a cross-sectional view schematically showing a laminate according to a second embodiment of the invention. FIG. 3 is a cross-sectional view schematically showing a laminate according to a third embodiment of the invention. FIG. 4 is a cross-sectional view schematically showing a laminate according to a fourth embodiment of the invention. FIG. 5 is a cross-sectional view schematically showing a laminate according to a fifth embodiment of the invention. FIG. 6 is a cross-sectional view schematically showing a laminate according to a sixth embodiment of the invention. FIG. 7 is a diagram schematically showing a packaged article according to a seventh embodiment of the invention. FIG. 8 is a diagram schematically showing a packaged article according to an eighth embodiment of the invention. FIG. 9 is a diagram schematically showing a packaged article according to a ninth embodiment of the invention.

Embodiments of the present invention will be described below with reference to the drawings. Embodiments described below are more specific to any of the above aspects. The matters described below can be incorporated into each of the above aspects singly or in combination.

Further, the embodiments shown below are examples of configurations for embodying the technical idea of the present invention. is not limited by Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

Elements having the same or similar functions are given the same reference numerals in the drawings referred to below, and duplicate descriptions are omitted. Accordingly, matters referred to in one embodiment are also applicable to other embodiments unless otherwise stated. Also, the drawings are schematic, and the relationship between the dimension in one direction and the dimension in another direction, the relationship between the dimension of a certain member and the dimension of another member, etc. may differ from the actual one. can differ.

In addition, in the present disclosure, the description "AA on BB" is used regardless of the direction of gravity. The condition identified by the statement "AA on BB" encompasses the condition where AA is in contact with BB. Reference to "AA over BB" does not exclude the interposition of one or more other components between AA and BB.

<1> First Embodiment <1.1> Laminate Fig. 1 is a sectional view schematically showing a laminate according to a first embodiment of the present invention.
A laminate 10A shown in FIG. 1 includes a substrate layer 2, a gas barrier layer 3, an adhesive layer 6, and a sealant layer 7 in this order. 10 A of laminated bodies may further contain the printing layer between the base material layer 2 and the sealant layer 7. FIG. The printed layer shows characters, patterns, etc., and is provided as necessary for the purpose of displaying information about the contents, identifying the contents, or improving the design of the packaging bag. As for the printed layer, the description in the section of "<2.3> Printed layer" in the second embodiment described below can be referred to.

The ratio of polyethylene in the laminate 10A is 90% by mass or more. Here, the ratio of polyethylene in the laminate 10A means the ratio of the total amount of polyethylene to the total amount of the resin material in each layer constituting the laminate 10A. High recyclability can be achieved by setting the proportion of polyethylene to 90% by mass or more.

Each layer included in the laminate 10A will be described below.

<1.2> Base material layer The base material layer 2 contains polyethylene. Polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and other monomers. When polyethylene is a copolymer of ethylene and other monomers, the proportion of ethylene in the copolymer is, for example, 80 mol % or more.

Other monomers are, for example, α-olefins. By way of example, the α-olefins range from 3 to 20 carbon atoms. Such α-olefins are, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1- eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, or 6-methyl-1-heptene.

The polyethylene may be a copolymer of ethylene and one of vinyl acetate and acrylic acid ester.

The base material layer 2 is, for example, high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), or very low density polyethylene (VLDPE). Among these, high-density polyethylene and medium-density polyethylene are preferable from the viewpoint of the printability, strength and heat resistance of the laminate 10A and the film stretchability, and medium-density polyethylene is more preferable from the viewpoint of stretchability.

Here, high-density polyethylene has a density of 0.942 g/cm ³ or more, medium-density polyethylene has a density of 0.930 g/cm ³ or more and less than 0.942 g/cm ³ , and low-density polyethylene has a density of is 0.910 g/cm ³ or more and less than 0.930 g/cm ³ , the linear low density polyethylene has a density of 0.910 g/cm ³ or more and less than 0.930 g/cm ³ , and the ultra-low density polyethylene has a density of is less than 0.910 g/cm ³ .
The density is a value obtained by a method conforming to JIS K7112:1999.

The polyethylene contained in the base material layer 2 may be biomass-derived polyethylene. As biomass-derived polyethylene, for example, green polyethylene (manufactured by Braskem) can be used.

Alternatively, the polyethylene contained in the base material layer 2 may be polyethylene recycled by mechanical recycling. Here, mechanical recycling means pulverizing the recovered polyethylene film or the like, then cleaning the pulverized film with alkali to remove dirt and foreign matter on the film surface, and then drying it at high temperature and under reduced pressure. It is to decontaminate the polyethylene film by dispersing the retained contaminants.

Alternatively, the polyethylene contained in the base material layer 2 may be polyethylene recycled by chemical recycling.

The melting point of the base material layer 2 is preferably within the range of 100°C to 140°C, more preferably within the range of 120°C to 140°C. The melting point is a value obtained by a method conforming to JIS K7121-1987.

The base material layer 2 has a birefringence ΔN measured by the parallel Nicols rotation method within the range of 0.01 to 0.1. Here, the birefringence ΔN is the absolute value of the difference between the refractive index of the substrate layer 2 in the MD direction (machine direction) and the refractive index of the substrate layer 2 in the TD direction (transverse direction). The birefringence ΔN can be measured using a phase difference measuring device KOBRA-WR (manufactured by Oji Scientific Instruments Co., Ltd.). In the measurement of the birefringence ΔN, the light source wavelength is set to 586.6 nm, and direct measurement using the parallel Nicols rotation method is performed. The birefringence ΔN measured by the parallel Nicols rotation method is also simply referred to as “birefringence ΔN” in this specification.

Preferably, the birefringence ΔN is measured for each of multiple locations on the substrate layer 2 , and the average value of the obtained birefringence ΔN is obtained as the birefringence ΔN of the substrate layer 2 . The plurality of locations of the base material layer 2 are, for example, the central portion and end portions of the base material layer 2 . The plurality of locations of the substrate layer 2 are preferably the central portion and both ends of the TD of the substrate layer 2 .

The birefringence ΔN of the base material layer 2 is preferably within the range of 0.01 to 0.052. Further, when the birefringence ΔN is in the range of 0.01 to 0.017, the drop strength is excellent, and when the birefringence ΔN is in the range of 0.017 to 0.052, the heat resistance is excellent.

It is believed that the secondary structure of the resin molecules that make up the film contributes to the large birefringence ΔN or large retardation. In addition, the basic physical properties of the film greatly change depending on the state of the molecular arrangement. Therefore, by adjusting the birefringence ΔN or the retardation, it becomes possible to design the functions to be imparted to the film. For example, if the anisotropy of the film is sufficiently large, it is possible to improve heat resistance and impart easy-to-cut properties. Reducing anisotropy increases toughness and improves impact resistance and puncture resistance.

The structure formed by the resin molecules in the film is related to, for example, the crystalline state, molecular orientation, compatibility state, uneven distribution of molecules, and the like.

The birefringence ΔN can be increased by uniaxially or biaxially stretching the film. When the draw ratio is large, the birefringence ΔN also becomes large. Also, the birefringence ΔN can be increased depending on the material of the base material layer 2 . The birefringence ΔN can be adjusted by stretching conditions such as the stretching ratio of the base material layer 2, film manufacturing conditions such as the density of the resin used, the type of comonomer, molecular weight, molecular weight distribution, and heat history, and the film forming method. can.

The base material layer 2 is preferably a stretched film. Stretched films are particularly excellent in heat resistance and strength. The stretched film may be a uniaxially stretched film or a biaxially stretched film. In this specification, the term "film" does not include the concept of thickness.

Using a uniaxially stretched film as the base material layer 2 improves the heat resistance during bag making. When a biaxially stretched film is used as the base material layer 2, the drop strength of the packaged article using the laminate 10A as the packaging material is improved.

Whether the stretched film is a uniaxially stretched film or a biaxially stretched film can be determined by performing in-plane measurement using a wide-angle X-ray diffraction method, as described below. The X-ray diffraction pattern obtained by this measurement contains information on the degree of orientation of molecular chains present on the film surface. An example of the measurement method is shown.

First, using a wide-angle X-ray diffractometer manufactured by Rigaku Corporation, out-of-plane measurement is performed by the parallel beam method. An X-ray diffraction pattern of the film to be measured is obtained by 2θ/θ scanning over a range of diffraction angles of 10° to 30°. _CuKα rays are used as the X-rays, and the X-rays are collimated by a multilayer film mirror and made incident on the base material layer 1 . A scintillation detector with a flat plate collimator is used as the light receiving unit.

From the obtained X-ray diffraction pattern, the peak area of the crystalline component and the halo pattern area of the amorphous component are obtained, and the ratio of the peak area of the crystalline component to the total area is calculated as the degree of crystallinity.
When the film to be measured has a plurality of layers, the crystallinity of one of the outermost surfaces of the film is measured.

When the film to be measured is a polyethylene film, scanning at a diffraction angle of 10° to 30° reveals two sharp crystal component peaks corresponding to the (110) plane and the (200) plane, A broad halo pattern of the amorphous component is observed.

In order to determine whether the film to be measured is a uniaxially stretched film or a biaxially stretched film, it is possible to use in-plane measurement by the X-ray diffraction method, as described above. In this in-plane measurement, the X-ray incident angle θ and the angle 2θ at which the diffracted X-rays are detected by the detector correspond to the specific crystal planes in the above out-of-plane measurement. Diffraction peaks, for example, the angle θ and angle 2θ when the diffraction peak corresponding to the (110) plane of a polyethylene film is detected are fixed, and in this state, the film to be measured is scanned in the in-plane direction. to obtain a diffraction pattern.

When in-plane measurement is performed on a uniaxially stretched film uniaxially stretched in the machine direction (MD), when the MD direction is defined as 0 °, a sharp diffraction peak corresponding to the (110) plane is formed at an angle 2θ of about A diffraction pattern with positions of ±90° can be obtained. On the other hand, in the case of a biaxially stretched film, the higher-order structure obtained by the uniaxial stretching is disturbed by the second stretching, and the anisotropy is reduced. A diffraction pattern having a uniform diffraction peak cannot be obtained. Therefore, in-plane measurements can be cited as one method of distinguishing monoaxially and biaxially stretched films from each other.

When a polymer film is uniaxially stretched, a higher-order structure called a shish kebab structure appears. The shish kebab structure consists of a shish structure, which is an extended chain crystal, and a kebab structure, which is a lamellar crystal. In a uniaxially stretched film, this higher-order structure is arranged with a high degree of order, so the X-ray diffraction pattern obtained by the above measurement for the uniaxially stretched film will contain sharp diffraction peaks. That is, when the above measurement is performed on the uniaxially stretched film, a clear diffraction peak appears. In addition, a "clear diffraction peak" means a diffraction peak with a half width of less than 10°.

On the other hand, in the production of biaxially stretched film, it is stretched in a specific direction and then in a direction perpendicular to the previous direction. Therefore, although the first drawing produces the above-described higher order structure, this higher order structure is disturbed by the second drawing. Therefore, when the above measurement is performed on the biaxially stretched film, the obtained X-ray diffraction pattern has a broad diffraction peak. That is, when the above measurement is performed on the biaxially stretched film, no clear diffraction peak appears.

As described above, the uniaxially stretched film and the biaxially stretched film have different X-ray diffraction patterns obtained by the above measurement. Therefore, based on this, it is possible to determine whether the stretched film is a monoaxially stretched film or a biaxially stretched film.

A stretched film can be obtained, for example, by stretching a film obtained by forming a polyethylene film by a T-die method or an inflation method. It is also possible to use, as the substrate layer 2, a multi-layered polyethylene film obtained by co-extrusion of polyethylenes having different densities.

As the base material layer 2, a multi-layered structure comprising a layer made of high density polyethylene (high density polyethylene layer) and a layer made of medium density polyethylene (medium density polyethylene layer) may be used. By providing the high-density polyethylene layer on the outside of the base material layer 2 (the side opposite to the sealant layer side), the strength and heat resistance of the laminate 10A can be further improved. In addition, since the substrate layer 2 is provided with a medium-density polyethylene layer, the stretchability of the resin film constituting the substrate layer 2 can be further improved.

The haze of the base material layer 2 is preferably 20% or less, more preferably 10% or less. The haze is a value obtained by a method conforming to JIS K7136:2000.

The thickness of the base material layer 2 is preferably in the range of 10 µm to 200 µm, more preferably in the range of 15 µm to 50 µm. If the base material layer 2 is too thin, the strength of the laminate 10A tends to decrease. Moreover, if the base material layer 2 is too thick, the processability of 10 A of laminated bodies will fall easily.

The base material layer 2 is preferably surface-treated. According to this treatment, the adhesion between the substrate layer 2 and the layer adjacent to the substrate layer 2 can be improved.

The surface treatment method is not particularly limited. Surface treatments include, for example, corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and/or nitrogen gas, physical treatment such as glow discharge treatment, and chemical treatment such as oxidation treatment using chemicals. processing.

The base material layer 2 may further contain additives. Examples of additives include cross-linking agents, antioxidants, anti-blocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins. is mentioned.

The proportion of polyethylene in the base material layer 2 is preferably 50% by mass or more, more preferably 80% by mass or more. According to one example, the substrate layer 2 consists of polyethylene. According to another example, the base layer 2 consists of polyethylene and additives.

<1.3> Gas Barrier Layer The gas barrier layer 3 functions as a barrier layer that suppresses permeation of oxygen and water vapor. A gas barrier layer consists of an inorganic compound layer, or consists of an inorganic compound layer and a coating layer.

Examples of inorganic compounds contained in the inorganic compound layer include vapor deposition layers made of metal oxides such as aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoint of transparency and barrier properties, the metal oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. Furthermore, considering the cost, it is selected from aluminum oxide and silicon oxide. By using the inorganic compound layer as a barrier film using a metal oxide, it is possible to obtain a high barrier property with a very thin layer that does not affect the recyclability of the laminate 10A.

The inorganic compound layer can be formed, for example, by vacuum deposition. A physical vapor deposition method or a chemical vapor deposition method can be used in vacuum deposition. Examples of the physical vapor deposition method include a vacuum deposition method, a sputtering method, an ion plating method, and the like, but are not limited to these. As the chemical vapor deposition method, thermal CVD method, plasma CVD method, light C
Examples include the VD method, but are not limited to these.

The film thickness of the inorganic compound layer made of aluminum oxide is preferably 5 nm or more and 30 nm or less. Sufficient gas-barrier property can be obtained as a film thickness is 5 nm or more. Further, when the film thickness is 30 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 gas barrier properties. If the film thickness exceeds 30 nm, the cost tends to increase due to an increase in the amount of material used and an increase in film formation time, which is not preferable from an economic point of view. From the same viewpoint as above, the film thickness of the inorganic compound layer is more preferably 7 nm or more and 15 nm or less.

The film thickness of the inorganic compound layer made of silicon oxide is preferably 10 nm or more and 50 nm or less. Sufficient gas-barrier property can be obtained as a film thickness is 10 nm or more. Further, when the film thickness is 50 nm or less, it is possible to suppress the generation of cracks due to deformation due to internal stress of the thin film, and to suppress deterioration of gas barrier properties. If the film thickness exceeds 50 nm, it is not preferable from an economical point of view because the cost tends to increase due to an increase in the amount of material used and an increase in film formation time. From the same viewpoint as above, the film thickness of the inorganic compound layer is more preferably 20 nm or more and 40 nm or less.

A known anchor coating agent may be used to form an anchor coating layer on the surface of the substrate layer 2 on which the inorganic compound layer is formed. Thereby, the adhesion of the inorganic compound layer made of metal oxide can be improved. Examples of anchor coating agents include polyester-based polyurethane resins and polyether-based polyurethane resins. Polyester-based polyurethane resins are preferred from the viewpoint of heat resistance and interlayer adhesive strength.

The coating layer protects the inorganic compound layer and exhibits barrier properties independently of the inorganic compound layer. The coating layer can be formed using an aqueous solution containing at least one selected from the group consisting of hydroxyl-containing polymer compounds, metal alkoxides, silane coupling agents, and hydrolysates thereof.

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

<1.4> Adhesive Layer The adhesive layer 6 contains at least one type of adhesive. The adhesive may be a one-component curable adhesive, a two-component curable adhesive, or a non-curable adhesive. Further, the adhesive may be a non-solvent adhesive or a solvent adhesive.

Examples of adhesives include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives such as polyamine adhesives, urethane adhesives, rubber adhesives, vinyl adhesives, and silicone adhesives. adhesives, epoxy adhesives, phenol adhesives and olefin adhesives. The adhesive is preferably a polyamine-based adhesive or a urethane-based adhesive having gas barrier properties. Adhesives containing biomass components can also be preferably used.

As the adhesive, an epoxy-based adhesive such as a polyamine-based adhesive having gas barrier properties, or a urethane-based adhesive such as a polyester/polyurethane-based adhesive is preferably used. Specific examples of gas barrier adhesives include "Maxieve" manufactured by Mitsubishi Gas Chemical Company and "Paslim" manufactured by DIC.

The adhesive layer 6 may be a cured product of a resin composition containing a polyester polyol, an isocyanate compound and a phosphoric acid-modified compound. Such an adhesive layer 6 is excellent in oxygen barrier properties and water vapor barrier properties of the laminate 10A.

The thickness of the adhesive layer 6 is preferably in the range of 0.1 μm to 20 μm, more preferably in the range of 0.5 μm to 10 μm, even more preferably in the range of 1 to 5 μm. .

The adhesive layer 6 is applied onto the substrate layer 2 by a conventionally known method such as a direct gravure roll coating method, a gravure roll coating method, a kiss coating method, a reverse roll coating method, a fonten method and a transfer roll coating method. It can be formed by drying.

<1.5> Sealant Layer The sealant layer 7 contains polyethylene. As the polyethylene, for example, the polyethylene contained in the base material layer 2 can be used. The sealant layer 7 is preferably low density polyethylene (LDPE), linear low density polyethylene (LLDPE) or very high density polyethylene (VLDPE), more preferably linear low density polyethylene.

From the perspective of environmental impact, polyethylene is preferably biomass-derived polyethylene or recycled polyethylene.

The sealant layer 7 may be transparent or opaque. In the latter case, the sealant layer 7 may be colored, preferably white. The laminate 10A having a transparent sealant layer 7 makes it easy to visually recognize the contents when the laminate is used as a package. When the laminate 10A in which the sealant layer 7 is opaque is used as a package, the content does not interfere with the visibility of the image displayed by the printed layer. In particular, the white sealant layer 7 improves the visibility of the image displayed by the printed layer.

The sealant layer 7 may further contain the additives described above.
The proportion of polyethylene in the sealant layer 7 is preferably 50% by mass or more, more preferably 80% by mass or more. According to one example, the sealant layer 7 consists of polyethylene. According to another example, the sealant layer 7 consists of polyethylene and additives.

The thickness of the sealant layer 7 can be appropriately set in consideration of the shape of the packaging bag to be manufactured, the mass of the content to be contained, and the like, and can be in the range of 30 to 150 μm, for example.

The sealant layer 7 is, for example, an unstretched polyethylene resin film or a layer formed by melt extrusion of polyethylene.

<1.6> Effects The laminate 10A described above has excellent heat resistance. This will be explained below.

In the production of packaging bags, generally, the sealant layers of the laminate are brought into contact with each other, and the contact portions are sandwiched between jigs to apply pressure and heat, thereby heat-sealing the contact portions. There is The jig of the heat-sealing machine is at a high temperature, and the surface of the base material layer in direct contact with the jig is exposed to high temperature. As a result, when polyethylene, which is inferior in heat resistance, is used for the substrate layer, the surface of the substrate layer may be affected by heat, causing problems such as adhesion to jigs. Therefore, conventional laminates using polyethylene as a base layer have a problem of poor productivity due to narrow appropriate bag-making temperature conditions.

The present inventors have found that when the birefringence ΔN of the base layer 2 is within the range of 0.01 to 0.1, the base layer 2 exhibits excellent heat resistance, and therefore the laminate 10A is also excellent. It has been found to exhibit heat resistance, in particular to achieve good heat-sealability.

In the laminate 10A, as the base layer 2, polyethylene, which is generally said to have poor heat resistance, is used. However, by setting the birefringence ΔN of the base material layer 2 within the range of 0.01 to 0.1, the temperature range of heat-sealing for bag making is widened, and productivity does not decrease.

Furthermore, the laminate 10A has a polyethylene content of 90% by mass or more. Therefore, the laminate 10A is also excellent in recyclability.

<1.7> Modification The laminate 10A may be further provided with a print layer, a protective layer, a light shielding layer, other functional layers, and the like, if necessary.

As described above, the laminate 10A may further include a printed layer between the base material layer 2 and the sealant layer 7. That is, the printed layer may be provided at any position between the base material layer 2 and the sealant layer 7 . For example, the printed layer can be provided between the substrate layer 2 and the gas barrier layer 3 (that is, the back surface of the substrate layer 2). In this case, when the laminate 10A is observed from the base material layer 2 side, the pattern displayed by the printed layer is likely to be clearly visible. Alternatively, the printed layer may be provided on the surface of the base material layer 2 . Also, a plurality of printed layers may be provided.

Further, an anchor coat layer may be formed on the main surface of the base material layer 2 that faces the gas barrier layer 3 . Moreover, the gas barrier layer 3 may be omitted.

In addition, a metal deposition layer may be provided on the base material layer 2 or the sealant layer 7 in order to impart light shielding properties to the laminate 10A. When the laminate 10A includes an intermediate layer, which will be described later, a metal deposition layer may be provided on the intermediate layer. An aluminum vapor deposition layer can be mentioned as a metal vapor deposition layer.

In addition, although it has already been stated that the sealant layer 7 may be opaque, the base layer 2 may also be opaque. The substrate layer 2 may be colored, for example white. When the laminate 10A includes an intermediate layer, which will be described later, the intermediate layer may be opaque. The intermediate layer may be colored, for example white.

<2> Second Embodiment <2.1> Laminate FIG. 2 is a cross-sectional view schematically showing a laminate according to a second embodiment of the present invention.
The laminate 10B shown in FIG. 2 further includes a protective layer 1 provided on the surface of the base material layer 2, and further includes a printed layer 5 between the gas barrier layer 3 and the adhesive layer 6. Other than that, it is the same as the laminate 10A. That is, the laminate 10B shown in FIG. 2 includes a protective layer 1, a base material layer 2, a gas barrier layer 3, a printing layer 5, an adhesive layer 6, and a sealant layer 7 in this order.

<2.2> Protective layer The protective layer 1 is the outermost layer facing the sealant layer 7 with the base material layer 2 interposed therebetween. Here, the protective layer 1 covers the surface of the base material layer 2 .

The protective layer 1 is made of a thermosetting resin. That is, the protective layer 1 is a thermosetting resin layer. The cured product of the thermosetting resin is not particularly limited as long as it has heat resistance. Thermosetting resins include, for example, polyurethane resins, polyester resins, polyamide resins, polyamideimide resins, acrylic resins, and epoxy resins. The protective layer 1 may contain one type of the above thermosetting resin, or may contain two or more types.

In one form, the protective layer 1 preferably contains a water-soluble polymer, and is preferably an organic-inorganic composite layer containing an organometallic compound.

Examples of water-soluble polymers include polyvinyl alcohol, polysaccharides such as starch, methylcellulose, carboxymethylcellulose, and hydroxyl group-containing polymers such as acrylic polyol. In one form, the protective layer 1 preferably contains a polyvinyl alcohol-based hydroxyl group-containing polymer that can be contained in a coating layer as the gas barrier layer 3 described later.

The protective layer 1 preferably contains at least one of a metal alkoxide, a hydrolyzate of a metal alkoxide, and a reaction product of a metal alkoxide or a hydrolyzate thereof as an organometallic compound. Examples _of metal alkoxides include those represented by _the general formula M(OR) _n such as tetraethoxysilane [Si( _OC2H5 ) ₄ ] and triisopropoxyaluminum [Al( _OC3H7 ) ₃ ]. mentioned.

The protective layer 1 further includes at least one of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a reaction product of the silane coupling agent or a hydrolyzate of the silane coupling agent as the organometallic compound. It is preferred to include

In one form, the protective layer 1 can be formed using a coating liquid for forming a coating layer as the gas barrier layer 3, which will be described later. Further, when the laminate 10B includes an inorganic compound layer and a coating layer as the gas barrier layer 3, the protective layer 1 is a layer formed using the same coating liquid as the coating liquid used to form the coating layer. you can

When the thickness of the protective layer 1 becomes thin, it tends to become difficult to achieve high heat resistance. The thickness of the protective layer 1 is preferably 0.3 μm or more in order to reduce or mitigate thermal damage during heat sealing. Moreover, when the thickness of the protective layer 1 increases, it tends to become difficult to sufficiently dry the resin coating film in the manufacturing process of the laminate 10B. From the viewpoint of productivity, the thickness of protective layer 1 is preferably 3 μm or less.

<2.3> Print Layer The print layer 5 is a layer made of ink and displays patterns such as characters and pictures. The inks are, for example, conventionally used ink binder resins such as urethane, acrylic, nitrocellulose, rubber, and vinyl chloride, various pigments, extenders, plasticizers, desiccants, stabilizers, etc. of additives are added. As the ink, it is preferable to use biomass-derived ink. A light-shielding ink can also be preferably used. Examples of light-shielding ink include white ink, black ink, silver ink, and sepia ink.

Examples of methods for forming the printing layer 5 include known printing methods such as offset printing, gravure printing, flexographic printing, and silk screen printing, and known printing methods such as roll coating, knife edge coating, and gravure coating. A coating method can be used.

<2.4> Effect The laminate 10B includes the protective layer 1 . As described above, the protective layer 1 reduces thermal damage during heat sealing on the surface of the laminate 10B. Therefore, the laminate 10B can achieve even better heat resistance, particularly better heat-sealability. Therefore, when the laminate 10B has the configuration described above, the temperature range for heat sealing for bag making is widened, and the decrease in productivity is less likely to occur.

Moreover, since the protective layer 1 is substantially transparent, even if the laminate 10B further includes the protective layer 1, the image displayed by the printed layer 5 can be visually recognized from the surface side.
That is, the laminate 10B has excellent transparency and further excellent heat resistance. Moreover, since the laminate 10B has a ratio of polyethylene of 90% by mass or more, it is also excellent in recyclability.

<2.5> Modification In FIG. 2, the laminate 10B includes the printed layer 5 between the gas barrier layer 3 and the adhesive layer 6. may be provided at any position. Since the base material layer 2 is transparent, even when the printed layer 5 is included between the protective layer 1 and the sealant layer 7, the printed layer 5 is visible when the laminate 10B is observed from the protective layer 1 side. You can clearly see the pattern. Alternatively, the print layer 5 may be omitted.

<3> Third Embodiment <3.1> Laminate Fig. 3 is a sectional view schematically showing a laminate according to a third embodiment of the present invention.
A laminate 10C shown in FIG. 3 is the same as the laminate 10A except for the following items. That is, the laminate 10C further includes the intermediate layer 4 and the print layer 5. As shown in FIG. Also, the laminate 10C includes a first adhesive layer 6A and a second adhesive layer 6B instead of the adhesive layer 6. As shown in FIG. That is, the laminate 10C includes the base material layer 2, the first adhesive layer 6A, the gas barrier layer 3, the intermediate layer 4, the printing layer 5, the second adhesive layer 6B, and the sealant layer 7. Including in order.

<3.2> Intermediate Layer The intermediate layer 4 is interposed between the base material layer 2 and the sealant layer 7 . The intermediate layer 4 contains polyethylene. In the laminate 10C, the intermediate layer 4 has a birefringence ΔN measured by the parallel Nicols rotation method within the range of 0.01 to 0.1, preferably within the range of 0.01 to 0.052. Such an intermediate layer 4 can contribute to improving the strength of the laminate 10C, particularly the puncture strength.

The "puncture strength" of the laminate is a value obtained when the laminate 10C is pierced from the base layer 2 side in the method specified in JIS Z1707:2019 "General Rules for Plastic Films for Food Packaging". Specifically, a needle with a diameter of 1 mm and a semicircular tip is pierced into the laminated body 10C from the base layer 2 side at a speed of 50 mm/min, and the maximum force until the needle penetrates is measured. do. This measurement is performed multiple times and the arithmetic mean of the maximum force is obtained as the puncture strength.

As the polyethylene contained in the intermediate layer 4, for example, the polyethylene contained in the base material layer 2 in the first embodiment can be used. The intermediate layer 4 is for example high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) or very low density polyethylene (VLDPE). Among these, high-density polyethylene and medium-density polyethylene are preferable from the viewpoint of printability, strength and heat resistance of the laminate 10C, and film stretchability, and medium-density polyethylene is more preferable from the viewpoint of stretchability.

The polyethylene contained in the intermediate layer 4 may be the same as or different from the polyethylene contained in the base material layer 2. In addition, the intermediate layer 4 may further contain the additives described above.

The proportion of polyethylene in the intermediate layer 4 is preferably 50% by mass or more, more preferably 80% by mass or more. According to one example, the intermediate layer 4 consists of polyethylene. According to another example, the intermediate layer 4 consists of polyethylene and additives.

The melting point of the intermediate layer 4 is preferably within the range of 100°C to 140°C, more preferably within the range of 120°C to 140°C.

The intermediate layer 4 is preferably a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. The stretched film forming the intermediate layer 4 may be the same as or different from the stretched film forming the base layer 2 .

Using a uniaxially stretched film as the intermediate layer 4 improves the heat resistance during bag making. When a biaxially oriented film is used as the intermediate layer 4, the drop strength of the packaged article using the laminate 10C as the packaging material is improved.

It should be noted that whether the stretched film is a uniaxially stretched film or a biaxially stretched film can be determined by performing in-plane measurement using the X-ray diffraction method, as described in the section of the first embodiment.

The thickness of the intermediate layer 4 is preferably in the range of 10 µm to 200 µm, more preferably in the range of 15 µm to 50 µm.

As the intermediate layer 4, one produced by the above-described T-die method or inflation method may be used.

The intermediate layer 4 is preferably surface-treated, like the base material layer 2 . According to this treatment, the adhesion between the intermediate layer 4 and the adjacent layer can be improved. The surface treatment method is not particularly limited. Surface treatments include, for example, corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and/or nitrogen gas, physical treatment such as glow discharge treatment, and chemical treatment such as oxidation treatment using chemicals. processing.

Note that in this embodiment, an intermediate layer having a birefringence ΔN of 0 to 0.01 as measured by the parallel Nicols rotation method may be used. By using an intermediate layer having a birefringence ΔN in this range, the strength of the laminate 10C, particularly drop strength, can be improved. The intermediate layer having a birefringence ΔN of 0 to 0.01 is preferably an unstretched film.

<3.3> Adhesive Layer The first adhesive layer 6A is interposed between the base material layer 2 and the gas barrier layer 3 and bonds them together. The second adhesive layer 6B is interposed between the printed layer 5 and the sealant layer 7 to bond them together. These adhesive layers improve adhesion between layers.

As the adhesive for forming the first adhesive layer 6A and the second adhesive layer 6B, the adhesive described in the section "<1.5> Adhesive layer" in the first embodiment can be used. can. The material of the second adhesive layer 6B may be the same as or different from the material of the first adhesive layer 6A.

The thickness of the first adhesive layer 6A and the second adhesive layer 6B is preferably in the range of 0.1 μm to 20 μm, more preferably in the range of 0.5 μm to 10 μm, and 1 to 5 μm. is more preferably within the range of

The first adhesive layer 6A and the second adhesive layer 6B are formed, for example, by a conventionally known method such as a direct gravure roll coating method, a gravure roll coating method, a kiss coating method, a reverse roll coating method, a fonten method and a transfer roll coating method. It can be formed by coating and drying on the base material layer 2 or the sealant layer 7 .

<3.4> Effect In the laminate 10C, the birefringence ΔN of the base material layer 2 is within the range of 0.01 to 0.1. Therefore, the laminated body 10C is excellent in heat resistance like the laminated body 10A.

The laminate 10C also includes an intermediate layer 4 having a birefringence ΔN within the range of 0.01 to 0.1. This intermediate layer 4 enhances the strength of the laminate 10C, especially the puncture strength. Therefore, the laminate 10C is excellent in strength, especially puncture strength.

Also, since the laminate 10C has a polyethylene ratio of 90% by mass or more, it is also excellent in recyclability.

In addition, laminates with a high proportion of polyethylene are weaker in stiffness than other laminates, and are therefore more likely to be bent when used as packaging materials. As the chances of bending increase, the possibility of pinhole formation increases. However, the laminated body 10C, which has excellent piercing strength, is less prone to pinhole formation.

<3.5> Modification In FIG. 3, the laminate 10C includes the printed layer 5 between the intermediate layer 4 and the second adhesive layer 6B. may be provided at any position between In 10 C of laminated bodies, the base material layer 2 and the intermediate|middle layer 4 are transparent. For this reason, even when the printed layer 5 is included in any position between the base layer 2 and the sealant layer 7, when the laminate 10C is observed from the base layer 2 side, the pattern displayed by the printed layer 5 can be seen clearly. Alternatively, the print layer 5 may be omitted.

Further, among the main surfaces of the base material layer 2, an anchor coat layer may be formed on the main surface facing the first adhesive layer 6A.

In FIG. 3, the laminate 10C includes the gas barrier layer 3 between the first adhesive layer 6A and the intermediate layer 4, but the laminate 10C includes the intermediate layer 4 and the second adhesive layer 6B. A gas barrier layer 3 may be included between. Alternatively, the gas barrier layer 3 may be omitted.

<4> Fourth Embodiment <4.1> Laminate Fig. 4 is a sectional view schematically showing a laminate according to a fourth embodiment of the present invention.
A layered body 10D shown in FIG. 4 is the same as the layered body 10C except that it further includes a protective layer 1 provided on the surface of the base material layer 2 and that the layering order is partially different. That is, the laminate 10D includes a protective layer 1, a base layer 2, a printing layer 5, a first adhesive layer 6A, an intermediate layer 4, a gas barrier layer 3, a second adhesive layer 6B, and a sealant. layer 7 in that order.

As the protective layer 1, the one described in the second embodiment can be used.

In the laminate 10D, the printed layer 5 is provided between the base material layer 2 and the first adhesive layer 6A. In this case, when the laminated body 10D is observed from the protective layer 1 side, the pattern displayed by the printed layer 5 can be seen more clearly.

<4.2> Effect In the laminate 10D, the birefringence ΔN of the base material layer 2 is within the range of 0.01 to 0.1. The laminated body 10</b>D includes a protective layer 1 . Therefore, the laminate 10D can achieve even better heat resistance, particularly better heat-sealability. Therefore, if the laminate 10D has the configuration described above, the temperature range for heat-sealing for bag making is widened, and productivity is less likely to decrease.

Moreover, since the protective layer 1 is substantially transparent, even if the laminate 10D further includes the protective layer 1, the image displayed by the printed layer 5 can be visually recognized from the surface side.
That is, the laminated body 10D is transparent and further excellent in heat resistance.

The laminate 10D also includes an intermediate layer 4 having a birefringence ΔN within the range of 0.01 to 0.1. This intermediate layer 4 enhances the strength of the laminate 10D, especially the puncture strength. Therefore, the laminate 10D is excellent in strength, especially puncture strength.

In addition, since the laminate 10D has a polyethylene ratio of 90% by mass or more, it is also excellent in recyclability.

<4.3> Modification In FIG. 4, the laminate 10D includes the printed layer 5 between the base material layer 2 and the first adhesive layer 6A. The printed layer 5 includes the protective layer 1 and the sealant layer 7 may be provided at any position between Since the base material layer 2 and the intermediate layer 4 are transparent, the laminate 10D can be observed from the protective layer 1 side regardless of where the printed layer 5 is included between the protective layer 1 and the sealant layer 7. In this case, the pattern displayed by the printed layer 5 can be clearly seen. Alternatively, the print layer 5 may be omitted.

Further, an anchor coat layer may be formed on the main surface of the base material layer 2 that faces the printed layer 5 . Moreover, the gas barrier layer 3 may be omitted.

<5> Fifth Embodiment <5.1> Laminate FIG. 5 is a cross-sectional view schematically showing a laminate according to a fifth embodiment of the present invention.
The laminate 10E shown in FIG. 10C. That is, the laminate 10E includes the substrate layer 2, the first adhesive layer 6A, the intermediate layer 4, the gas barrier layer 3, the second adhesive layer 6B, and the sealant layer 7 in this order. .

<5.2> Intermediate Layer In the laminate 10</b>E, the intermediate layer 4 is interposed between the base material layer 2 and the sealant layer 7 . The intermediate layer 4 contains polyethylene. In the laminate 10E, the intermediate layer 4 has a birefringence ΔN within the range of 0 to 0.01, preferably 0 or more and less than 0.01. In the laminate 10E, the intermediate layer 4 is preferably an unstretched film. Such an intermediate layer 4 improves adhesion between the intermediate layer 4 and the gas barrier layer 3, thereby making it difficult to separate the base layer 2 and the sealant layer 7 from each other in the laminate 10E.

Note that in this embodiment, an intermediate layer having a birefringence ΔN of 0.01 to 0.1 as measured by the parallel Nicols rotation method may be used. When the intermediate layer having the birefringence ΔN in the above range is used, the strength of the laminate 10E, particularly the puncture strength, can be improved. The intermediate layer having a birefringence ΔN of 0.01 to 0.1 is preferably a stretched film.

<5.3> Pretreatment Layer In the laminate 10E, a pretreatment layer (that is, an anchor coat layer) may be provided on the surface of the intermediate layer 4 on which the gas barrier layer 3 is provided. By providing the pretreatment layer, the film-forming properties and adhesion strength of the gas barrier layer 3 can be improved. There are no restrictions on the components and forming method of the pretreatment layer, and it can be selected from thermoplastic resins, thermosetting resins, ultraviolet curable resins, plasma treatment, and the like.

When a resin layer is used for the pretreatment layer, the content of the organic polymer in the pretreatment layer may be, for example, 70% by mass or more, or may be 80% by mass or more. Examples of organic polymers include polyacrylic resins, polyester resins, polycarbonate resins, polyurethane resins, polyamide resins, polyolefin resins, polyimide resins, melamine resins, and phenol resins. Considering this, it is preferable to include at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers. The pretreatment layer may also contain a silane coupling agent, organic titanate, or modified silicone oil.

More preferably, the organic polymer used in the pretreatment layer is an organic polymer having a urethane bond generated by a reaction between a polyol having two or more hydroxyl groups at the polymer end and an isocyanate compound, and/or a polymer. Organic polymers include reaction products of polyols having two or more terminal hydroxyl groups and organosilane compounds such as silane coupling agents or hydrolysates thereof.

Examples of polyols include at least one selected from acrylic polyols, polyvinyl acetals, polystyrene polyols, polyurethane polyols, and the like. The acrylic polyol may be obtained by polymerizing an acrylic acid derivative monomer, or may be obtained by copolymerizing an acrylic acid derivative monomer and another monomer. Acrylic acid derivative monomers include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of monomers to be copolymerized with acrylic acid derivative monomers include styrene.

The isocyanate compound has the effect of increasing the adhesion between the intermediate layer 4 and the gas barrier layer 3 through the urethane bond formed by reacting with the polyol. That is, the isocyanate compound functions as a cross-linking agent or curing agent. Examples of isocyanate compounds include monomers such as aromatic tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic xylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), and isophorone diisocyanate (IPDI). , polymers thereof, and derivatives thereof. The isocyanate compounds described above may be used singly or in combination of two or more.

Examples of silane coupling agents include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ- methacryloxypropylmethyldimethoxysilane and the like. The organosilane compound may be a hydrolyzate of these silane coupling agents. The organic silane compound may contain one of the above-mentioned silane coupling agents and hydrolysates thereof alone or in combination of two or more thereof.

The resin layer provided as the pretreatment layer can be formed by mixing the above-described components in an organic solvent at an arbitrary ratio to prepare a mixed solution, and applying the prepared mixed solution to the intermediate layer 4 . The mixture includes, for example, tertiary amines, imidazole derivatives, carboxylic acid metal salt compounds, quaternary ammonium salts, quaternary phosphonium salts and other curing accelerators; phenolic, sulfur, and phosphite antioxidants; A leveling agent; a flow control agent; a catalyst; a cross-linking reaction accelerator;

The mixture is applied to one side of the intermediate layer 4 using a known printing method such as offset printing, gravure printing, or silk screen printing, or a known coating method such as roll coating, knife edge coating, or gravure coating. can be coated on the major surfaces of After coating, a pretreatment layer can be formed by heating to, for example, 50 to 200° C. and drying and/or curing.

When a resin layer is formed as a pretreatment layer, the thickness may be adjusted according to the application or required properties, but is preferably 0.01 to 1 μm, more preferably 0.01 to 0.5 μm. If the thickness of the pretreatment layer is 0.01 μm or more, sufficient adhesion strength between the intermediate layer 4 and the gas barrier layer 3 can be obtained, and the gas barrier properties are also improved. If the thickness of the pretreatment layer is 1 μm or less, it is easy to form a uniform coating surface, and the drying load and manufacturing cost can be suppressed.

When the pretreatment layer is formed by plasma treatment, in-line plasma treatment is preferable from the viewpoint of productivity. The method of plasma treatment is not particularly limited, such as glow discharge, and a magnet may be used to increase the plasma density. Gas used for plasma treatment can be selected from one or more of oxygen, nitrogen, and argon.

<5.4> Effect In the laminate 10E described above, the birefringence ΔN of the base material layer 2 is in the range of 0.01 to 0.1. Therefore, the layered product 10E is excellent in heat resistance like the layered product 10A. Furthermore, the laminate 10E is excellent in tearability. Therefore, the packaging bag manufactured from the laminate 10E can be easily opened by hand. This effect will be explained below.

The problem with laminates made by laminating multiple resin films is that they have high tear strength. The inventors have found that the tear strength of the laminate 10E can be reduced when the birefringence ΔN of the base material layer 2 is within the range of 0.01 to 0.1. In the present invention, "good tearability" means that the tear strength is 100 N/mm or less. The tear strength is a value measured by the trouser tear method in accordance with JIS K 7128-1. Tear strength values can vary depending on the direction of tearing, but a sufficiently low tear strength in one direction can form a packaging material that is easy to open. Based on this, the tear strength in the present invention is measured in the MD direction and the TD direction, and the lower value is adopted.

In addition, the laminate 10E includes an intermediate layer 4 having a birefringence ΔN within the range of 0 to 0.01, preferably 0 or more and less than 0.01. As described above, such an intermediate layer 4 improves the adhesion between the intermediate layer 4 and the gas barrier layer 3, thereby making it difficult to separate the base layer 2 and the sealant layer 7 from each other in the laminate 10E. can.

Moreover, since the laminate 10E has a polyethylene ratio of 90% by mass or more, it is also excellent in recyclability.

<5.5> Modification The laminate 10E may be further provided with a print layer, a protective layer, a light shielding layer, other functional layers, and the like, if necessary.

For example, the printed layer may be provided at any position between the base layer 2 and the intermediate layer 4. Since the substrate layer 2 is transparent, even when the printed layer is included between the substrate layer 2 and the intermediate layer 4, when the laminate 10E is observed from the substrate layer 2 side, the printed layer is visible. The displayed pattern can be clearly seen. For example, the printed layer can be provided between the substrate layer 2 and the first adhesive layer 6A.

The gas barrier layer 3 may be provided on the surface on the base layer 2 side instead of the surface on the sealant layer 7 side. Alternatively, the gas barrier layer 3 may be provided on both surfaces of the intermediate layer 4 . Alternatively, the gas barrier layer 3 may be omitted.

<6> Sixth Embodiment <6.1> Laminate Fig. 6 is a sectional view schematically showing a laminate according to a sixth embodiment of the present invention.
The laminate 10F shown in FIG. 6 further includes a protective layer 1 provided on the surface of the base material layer 2, and further includes a printed layer 5 between the base material layer 2 and the first adhesive layer 6A. It is the same as the laminate 10E except that it is included. As the protective layer 1, the one described in the second embodiment can be used. As the printing layer 5, the one described in the second embodiment can be used.

<6.2> Effect In the laminate 10F, the birefringence ΔN of the base material layer 2 is within the range of 0.01 to 0.1. The laminate 10F includes a protective layer 1. As shown in FIG. Therefore, the laminate 10F can achieve even better heat resistance, particularly better heat-sealability. Therefore, if the laminate 10F has the configuration described above, the temperature range for heat-sealing for bag making is widened, and productivity is less likely to decrease.

Moreover, since the protective layer 1 is substantially transparent, even if the laminate 10F further includes the protective layer 1, the image displayed by the printed layer 5 can be visually recognized from the surface side.
That is, the laminated body 10F is transparent and further excellent in heat resistance.

In addition, the laminate 10F includes an intermediate layer 4 having a birefringence ΔN within the range of 0 to 0.01, preferably 0 or more and less than 0.01. The intermediate layer 4 enhances the strength of the laminate 10F, particularly drop strength. That is, in the laminate 10F, the intermediate layer 4 positioned inside the base material layer 2 is softer than the base material layer 2 when used in a package. This structure is suitable for absorbing the impact that occurs when a packaged article using the laminate 10F as a packaging material is dropped. Therefore, a packaged article using the laminate 10F as a packaging material is less likely to be damaged (broken bag) due to dropping. Therefore, the laminate 10F is excellent in strength, particularly drop strength.

Also, since the laminate 10F has a polyethylene ratio of 90% by mass or more, it is also excellent in recyclability.

<6.3> Modification In FIG. 6, the laminate 10F includes the printed layer 5 between the base material layer 2 and the first adhesive layer 6A. may be provided at any position between Since the substrate layer 2 is transparent, even when the printed layer 5 is included between the protective layer 1 and the intermediate layer 4, when the laminate 10F is observed from the protective layer 1 side, the printed layer 5 is visible. The displayed pattern can be clearly seen. Alternatively, the print layer 5 may be omitted.

<7> Seventh Embodiment FIG. 7 is a diagram schematically showing a packaged product according to a seventh embodiment of the present invention.

A packaged article 100A shown in FIG. 7 includes a package 110A and contents housed therein.

The package 110A is a flat pouch. The package 110A includes a pair of main body films. Each of the main films is either one of the laminates described in the first to sixth embodiments, or is cut from it. The body films are stacked with their sealant layers facing each other and heat sealed to each other at their peripheral edges. The package 110A is provided with a notch as an easy-to-open structure in its heat-sealed portion.

The contents may be liquid, solid, or a mixture thereof. The content is, for example, food or medicine.

<8> Eighth Embodiment FIG. 8 is a diagram schematically showing a packaged product according to an eighth embodiment of the present invention.

A packaged article 100B shown in FIG. 8 includes a package 110B and contents accommodated therein. The contents are, for example, the same as those described for the packaged article 100A.

The package 110B is a standing pouch. Package 110B includes a pair of main and bottom films. Each of these films is, or is cut from, any of the laminates described in the first through sixth embodiments.

A pair of main body films are superimposed so that their sealant layers face each other, and their peripheral edges are heat-sealed to each other except for one end and a region in the vicinity thereof. The bottom film is folded in two so as to form a mountain fold when viewed from the sealant layer side, and is sandwiched between the pair of main films at the position of the one end so that the mountain fold faces the other end of the main film. . The bottom film is heat-sealed to the pair of main films except for the central portion. Further, the outer surfaces of the bottom film are adhered to each other at positions on both sides of the bottom of the package 110B.

The package 110B is provided with a notch as an easy-to-open structure in the portion where the main films are heat-sealed. The easy-open structure may be provided so that when the packaged article 100B is opened, the upper corner can be used as a mouth. Alternatively, the packaged article 100B may further include the spout member and lid described in the ninth embodiment.

<9> Ninth Embodiment FIG. 9 is a diagram schematically showing a packaged product according to a ninth embodiment of the present invention.

A packaged product 100C shown in FIG. 9 includes a package 110C and contents housed therein. The contents are, for example, the same as those described for the packaged article 100A.

The package 110C is a gusset type pouch. The package 110C includes a container body 110C1, a mouth member 110C2, and a lid 110C3.

The container body 110C1 includes a pair of body films and a pair of side films.

A pair of main body films are superimposed so that their sealant layers face each other and part of the mouth member 110C2 is sandwiched between one ends. The peripheral edge portions of these main films are heat-sealed to the mouth member 110C2 at the one end and heat-sealed to each other in the vicinity thereof. In addition, the peripheral edge portions of these main films are heat-sealed to each other at the opposite ends except for the areas on both sides.

Each of the side films is folded in two so as to form a mountain fold when viewed from the sealant layer side. These side films are sandwiched between a pair of main films on both sides of the main films so that the mountain folds face each other. Each of the side films has a portion of its peripheral edge heat-sealed to one of the body films and the remaining portion of its peripheral edge heat-sealed to the other of the body films. In addition, the outer surfaces of the side films are adhered to each other at the upper and lower positions of the package 110C.
Note that the container body 110C1 may further include a bottom film.

As described above, the mouth member 110C2 includes a portion that is sandwiched between the main films and that are heat-sealed. The mouth member 110C2 further includes a mouth protruding outward from the container body 110C1. The mouth portion has a substantially cylindrical shape and is provided with a male thread on the outer surface of the side wall. The lid 110C3 has a cylindrical shape with a bottom. The lid 110C3 has a female screw on the inner side wall and is screwed with the mouth of the mouth member 110C2.

Below are the results of tests conducted in relation to the present invention.

(1) Test A
(1.1) Production of laminate (1.1.0) Preparation of coating solution (Preparation of mixed solution for gas barrier coating layer)
A liquid, B liquid, and C liquid shown below were mixed in a mass ratio of 70/20/10, respectively, to obtain a mixed liquid for a gas barrier coating layer.
_A solution: Solid content 5% by mass ₍ _SiO ₂ equivalent) hydrolysis solution.
B solution: 5 mass % water/methanol solution of polyvinyl alcohol (mass ratio of water:methanol is 95:5).
Solution C: 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate was diluted with a mixture of water/isopropyl alcohol (mass ratio of water:isopropyl alcohol is 1:1) to a solid content of 5% by mass. Hydrolysis solution.

(Preparation of Adhesive for Adhesive Layer Formation)
Two types of adhesives used for the adhesive layer are shown below.
・Urethane-based adhesive An adhesive obtained by mixing 100 parts by mass of Takelac A525 manufactured by Mitsui Chemicals, 11 parts by mass of Takenate A52 manufactured by Mitsui Chemicals, and 84 parts by mass of ethyl acetate ・Gas barrier adhesive Ethyl acetate and methanol An adhesive obtained by mixing 16 parts by mass of Maxieve C93T manufactured by Mitsubishi Gas Chemical Co., Ltd. and 5 parts by mass of Maxieve M-100 manufactured by Mitsubishi Gas Chemical Co., Ltd. into 23 parts by mass of a solvent mixed at a mass ratio of 1:1.

(1.1.1) Example 1A
A polyethylene film (thickness: 25 μm, density: 0.950 g/cm ³ , birefringence ΔN: 0.0238, single-sided corona treatment) was used as the substrate layer, and one surface of the substrate layer was coated with a vacuum deposition apparatus using an electron beam heating method. was used to form a silicon oxide layer having a thickness of 10 nm, and an inorganic compound layer was formed as a gas barrier layer.

A pattern was printed on the inorganic compound layer by gravure printing to form a printed layer. The urethane-based adhesive was applied on the printed layer by gravure coating and dried to form an adhesive layer with a thickness of 3 μm.
A 60 μm-thick film made of LLDPE was used as the sealant layer.

The printed layer and the sealant layer were coated with the above urethane-based adhesive by gravure coating and dried to form an adhesive layer having a thickness of 3 μm, and the respective layers were adhered by dry lamination.
Thus, a laminate according to Example 1A was obtained.

(1.1.2) Example 2A
A laminate according to Example 2A was obtained in the same manner as in Example 1A except that the printed layer and the sealant layer were laminated via the urethane-based adhesive without forming the inorganic compound layer.

(1.1.3) Example 3A
A laminate according to Example 3A was obtained in the same manner as in Example 1A, except that the polyamine-based gas barrier adhesive was used as the adhesive.

(1.1.4) Example 4A
Example 4A was prepared in the same manner as in Example 1A, except that the gas barrier coating layer mixture was applied onto the inorganic compound layer by gravure coating, dried and cured to form a coating layer having a thickness of 0.3 μm. was obtained. In the laminate according to Example 4A, the gas barrier layer consists of an inorganic compound layer and a coating layer.

(1.1.5) Example 5A
A laminate according to Example 5A was prepared in the same manner as in Example 4A, except that a polyethylene film (thickness 25 μm, density 0.950 g/cm ³ , birefringence ΔN 0.0412, single-sided corona treatment) was used as the base layer. got

(1.1.6) Example 6A
A laminate according to Example 6A was prepared in the same manner as in Example 4A, except that a polyethylene film (thickness 25 μm, density 0.950 g/cm ³ , birefringence ΔN 0.0119, corona treatment on one side) was used as the base layer. got

(1.1.7) Example 7A
A laminate according to Example 7A was prepared in the same manner as in Example 1A, except that a polyethylene film (thickness 20 μm, density 0.950 g/cm ³ , birefringence ΔN 0.0238, single-sided corona treatment) was used as the base layer. got

(1.1.8) Example 8A
A laminate according to Example 8A was prepared in the same manner as in Example 1A, except that a polyethylene film (thickness 30 μm, density 0.950 g/cm ³ , birefringence ΔN 0.0238, single-sided corona treatment) was used as the base layer. got

(1.1.9) Example 9A
A laminate according to Example 9A was obtained in the same manner as in Example 1A except that a linear low-density polyethylene resin (LLDPE) film having a thickness of 40 μm was used as the sealant layer.

(1.1.10) Example 10A
A laminate according to Example 10A was obtained in the same manner as in Example 1A except that a linear low-density polyethylene resin (LLDPE) film having a thickness of 120 μm was used as the sealant layer.

(1.1.11) Example 11A
A laminate according to Example 11A was obtained in the same manner as in Example 1A except that no inorganic compound layer was formed and a polyamine gas barrier adhesive was used instead of the urethane adhesive.

(1.1.12) Example 12A
Lamination according to Example 12A was performed in the same manner as in Example 1A, except that no inorganic compound layer was formed and a urethane-based gas barrier adhesive was used instead of the urethane-based adhesive. got a body

(1.1.13) Comparative Example 1A
Lamination according to Comparative Example 1A was carried out in the same manner as in Example 1A, except that a polyethylene film (thickness 32 μm, density 0.950 g/cm ³ , birefringence ΔN 0.0029, corona treatment on one side) was used as the substrate layer. got a body

(1.1.14) Comparative Example 2A
Lamination according to Comparative Example 2A was performed in the same manner as in Example 1A, except that a polyethylene film (thickness 25 μm, density 0.952 g/cm ³ , birefringence ΔN 0.0051, corona treatment on one side) was used as the substrate layer. got a body

(1.2) Evaluation method (1.2.1) Evaluation method for heat resistance at 140 ° C. Cut out a sample piece of 10 cm square from the above laminate, fold it in two so that the sealant layer is on the inside, and use a heat seal tester. was heat-sealed under the conditions of 140° C., 0.1 MPa, and 1 second. The resulting heat-sealed sample piece was visually evaluated based on the following evaluation criteria.
A: The surface is not melted and there is no problem in appearance. B: The surface is melted and there is a problem in appearance.

(1.2.2) Method for evaluating heat resistance at 170°C A sample piece of 10 cm square was obtained by cutting the above laminate. The sample strip was then folded in half with the sealant layer on the inside. Next, the lower surface sealing temperature of the heat seal tester was fixed at 30° C., and the upper surface sealing temperature was set at 170° C., and a pressure of 0.2 MPa was applied to the sample piece folded in two for 1 second. Then, the presence or absence of melting of the sealing surface was observed, and it was also observed whether or not the area of the upper surface of the sample piece folded in two against which the heat seal bar was applied adhered to the heat seal bar. Heat resistance was evaluated based on the following evaluation criteria.
A: The upper surface of the sample piece did not adhere to the heat seal bar.
B: The upper surface of the sample piece adhered to the heat seal bar.

(1.2.3) Evaluation Method for Visibility The laminate was visually observed, and the visibility of the printed layer from the substrate layer side was evaluated based on the following evaluation criteria.
A: The printed pattern is clearly visible. B: The printed pattern is blurred and looks pale.

(1.2.4) Method for evaluating gas barrier properties The oxygen permeability (cc/m ² ·day · atm) of the above laminate in an atmosphere of 30 ° C. and 70% RH was measured according to JIS K7126-2:2006. (isobaric method) and measured using an oxygen permeability measuring device. Based on the measurement results, gas barrier properties were evaluated based on the following evaluation criteria.
A: Oxygen transmission rate (OTR) is less than 10 cc B: Oxygen transmission rate (OTR) is 10 cc or more.

(1.2.5) In-Plane Measurement by X-Ray Diffraction Method The substrate layer used in the production of the laminate was subjected to in-plane measurement by X-ray diffraction method as described above. It was examined whether sharp diffraction peaks corresponding to the (110) plane were obtained in the obtained diffraction pattern.

(1.3) Results The results of the above evaluation are shown in Table 1 below.

As shown in Table 1, the laminates in which the birefringence ΔN of the substrate layer was within the range of 0.01 to 0.1 all had good heat resistance and visibility. On the other hand, all laminates in which the birefringence ΔN of the base material layer is less than 0.01 were insufficient in heat resistance and visibility.

(2) Test B
(2.1) Production of laminate (2.1.0) Preparation of coating liquid (Preparation of anchor coating agent)
Acrylic polyol and tolylene diisocyanate are mixed so that the number of NCO groups of tolylene diisocyanate is equal to the number of OH groups of acrylic polyol, and the total solid content (total amount of acrylic polyol and tolylene diisocyanate ) was diluted with ethyl acetate to 5% by mass. To the mixed solution after dilution, β-(3,4-epoxycyclohexyl)trimethoxysilane was further added so as to be 5 parts by mass with respect to the total amount of 100 parts by mass of the acrylic polyol and tolylene diisocyanate. An anchor coating agent was prepared by mixing.

(Preparation of coating liquid for coating layer formation)
An overcoat agent was prepared by mixing the following A liquid, B liquid, and C liquid at a mass ratio of 70/20/10, respectively.
_Solution _A : Solid content of 5% by mass ( _SiO ₂ equivalent) hydrolysis solution.
B solution: 5 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 with a mixture of water/isopropyl alcohol (mass ratio of water:isopropyl alcohol was 1:1) to a solid content of 5% by mass. Hydrolysis solution.

(Coating liquid for forming protective layer)
An organic solvent-based coating solution (VYLOMAX HR-15ET) containing polyamide-imide manufactured by Toyobo Co., Ltd. is diluted with a solvent (ethanol/toluene = 1/1) so that the concentration of non-volatile components is 5% by mass, forming a protective layer. It was used as a coating solution for

(2.1.1) Example 1B
A laminate 10B shown in FIG. 2 was manufactured by the following method.
First, as the base material layer 2, the following films were prepared. The prepared film consisted of polyethylene and had a birefringence ΔN of 0.0238, a haze of 1.6%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

After performing corona treatment on one surface of the substrate layer 2, the above-mentioned "coating solution for forming a protective layer" was applied by gravure coating and dried to form a protective layer having a thickness of 0.5 µm. .

Next, on the corona-treated surface opposite to the substrate layer 2, a 40 nm-thick inorganic compound layer composed of a silicon oxide (SiOx) deposited film is formed using an electron beam heating type vacuum deposition device, and , the above-mentioned "coating liquid for coating layer formation", that is, the organic/inorganic coating mixed liquid was applied to form a coating layer having a thickness of 0.3 µm. Thus, a gas barrier layer 3 composed of an inorganic compound layer and a coating layer was formed.

Next, a pattern was printed on the gas barrier layer 3 using gravure ink to form a printed layer 5 . Next, a urethane-based adhesive for dry lamination (Takelac A525/Takenate A52 manufactured by Mitsui Chemicals, Inc.) is applied as an adhesive to the print layer surface, and a linear low-density polyethylene resin (LLDPE) film (thickness 60 μm) is applied as the sealant layer 7. ) were bonded together to form a laminate 10B. The thickness of the adhesive layer 6 was 3 μm. FIG. 2 shows a schematic cross-sectional view of a laminate 10B according to Example 1B.

(2.1.2) Example 2B
A laminate according to Example 2B was produced in the same manner as the laminate according to Example 1B, except that the following films were used as the base material layer 2 . The film used consisted of polyethylene and had a birefringence ΔN of 0.0119, a haze of 5.9%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

(2.1.3) Example 3B
A laminate according to Example 3B was produced in the same manner as in Example 2B, except that the protective layer 1 was not formed.

(2.1.4) Example 4B
Instead of forming a protective layer with a thickness of 0.5 μm by applying a polyamideimide resin, the above-described “coating liquid for forming a coating layer” was applied to form a protective layer with a thickness of 0.5 μm. A laminate according to Example 4B was manufactured in the same manner as in Example 1B, except for the above.

(2.1.5) Example 5B
The same as Example 1B except that instead of applying a polyamideimide resin to form a protective layer with a thickness of 0.5 μm, a urethane-based resin was applied to form a protective layer with a thickness of 0.5 μm. A laminate according to Example 5B was produced by the method.

(2.1.6) Example 6B
The same as Example 1B except that instead of applying a polyamideimide resin to form a protective layer with a thickness of 0.5 μm, a urethane-based resin was applied to form a protective layer with a thickness of 1.0 μm. A laminate according to Example 6B was produced by the method.

(2.1.7) Example 7B
Except that instead of forming a protective layer with a thickness of 0.5 μm by applying a polyamide-imide resin, an ethylene vinyl alcohol copolymer resin (EVOH) was applied to form a protective layer with a thickness of 1.0 μm. A laminate according to Example 7B was produced in the same manner as in Example 1B.

(2.1.8) Example 8B
The same method as in Example 1B, except that instead of applying a polyamideimide resin to form a protective layer with a thickness of 0.5 μm, an acrylic resin was applied to form a protective layer with a thickness of 1.0 μm. to produce a laminate according to Example 8B.

(2.1.9) Comparative Example 1B
A laminate according to Comparative Example 1B was produced in the same manner as the laminate according to Example 1B, except that the following film was used as the base material layer 2 and the protective layer 1 was omitted. The film used was made of polyethylene and had a birefringence ΔN of 0.0029, a haze of 21.5%, a thickness of 32 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

(2.2) Evaluation method (2.2.1) Evaluation method for heat resistance at 140°C It was heat-sealed under conditions of 140° C., 0.1 MPa, and 1 second. The heat resistance was visually evaluated based on the following evaluation criteria.
A: No wrinkles on the surface, does not adhere to the seal bar B: Wrinkles on the surface, adheres to the seal bar.

(2.2.2) Method for evaluating heat resistance at 170°C and 190°C A sample piece of 10 cm square was obtained by cutting the above laminate. The sample strip was then folded in half with the sealant layer on the inside. Next, the lower surface sealing temperature of the heat seal tester was fixed at 30° C., and the upper surface sealing temperature was set at 170° C., and a pressure of 0.2 MPa was applied to the sample piece folded in two for 1 second. Then, the presence or absence of melting of the sealing surface was observed, and it was also observed whether or not the area of the upper surface of the sample piece folded in two against which the heat seal bar was applied adhered to the heat seal bar. Heat resistance was evaluated based on the following evaluation criteria.
A: The upper surface of the sample piece did not adhere to the heat seal bar.
B: The upper surface of the sample piece adhered to the heat seal bar.

In addition, the heat resistance of the laminate having a protective layer was further evaluated in the same manner as above, except that the upper surface sealing temperature was set to 190°C.

(2.2.3) Evaluation Method for Visibility The laminate was visually observed, and the visibility of the printed layer from the substrate layer side was evaluated based on the following evaluation criteria.
A: The printed pattern is clearly visible. B: The printed pattern is blurred and looks pale.

(2.2.4) Recyclability Evaluation Method Regarding the above laminate, the mass ratio of polyethylene (PE) to the total mass of the laminate was calculated, and the recyclability was evaluated according to the following criteria.
A: Ratio of polyethylene 90% by mass or more B: Ratio of polyethylene less than 90% by mass.

(2.2.5) In-plane Measurement by X-ray Diffraction Method The substrate layer used in the production of the laminate was subjected to in-plane measurement by X-ray diffraction method as described above. It was examined whether sharp diffraction peaks corresponding to the (110) plane were obtained in the obtained diffraction pattern.

(2.3) Results Table 2 shows the results of the above evaluation.

As shown in Table 2, the laminates in which the birefringence ΔN of the substrate layer was within the range of 0.01 to 0.1 all had good heat resistance and visibility. A laminate having a base layer with a birefringence ΔN in the range of 0.01 to 0.1 and having a protective layer was particularly excellent in heat resistance. On the other hand, a laminate having a substrate layer having a birefringence ΔN of less than 0.01 and having no protective layer had insufficient heat resistance and visibility.

(3) Test C
(3.1) Production of laminate (3.1.1) Example 1C
A laminate 10C shown in FIG. 3 was manufactured by the following method.
First, as the base material layer 2 and the intermediate layer 4, the following film F1 was prepared. The prepared film F1 consisted of polyethylene and had a birefringence ΔN of 0.0421, a haze of 1.6%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. and is corona treated on one side. Birefringence ΔN was measured on the corona-treated surface.

Next, a layer made of silicon oxide was formed as the gas barrier layer 3 on the intermediate layer 4 . The thickness of the gas barrier layer 3 was 50 nm.

Next, a urethane-based adhesive is applied onto the base material layer 2 to form a first adhesive layer 6A. and pasted together.

Next, a printed layer 5 was formed on the intermediate layer 4 . Next, a sealant layer 7 is prepared, a urethane-based adhesive is applied on the sealant layer 7 to form a second adhesive layer 6B, and an intermediate adhesive layer 6B is formed through the printed layer 5 and the second adhesive layer 6B. Layer 4 and sealant layer 7 were laminated together. Linear low density polyethylene (LLDPE) was used as the material for the sealant layer.
Thus, a laminate according to Example 1C was produced.

(3.1.2) Example 2C
Example 2C was prepared in the same manner as the laminate according to Example 1C, except that polyamine-based adhesives were used instead of urethane-based adhesives as materials for the first adhesive layer 6A and the second adhesive layer 6B. A laminate according to was manufactured. This polyamine-based adhesive had gas barrier properties.

(3.1.3) Example 3C
A laminate according to Example 3C was produced in the same manner as the laminate according to Example 1C, except that the following film F2 was used as the base layer. The film F2 used is a longitudinally uniaxially stretched film made of high-density polyethylene. This film F2 has a birefringence ΔN of 0.04121, a haze of 4.1%, a thickness of 25 μm, a density of 0.950 g/cm ³ , and one-sided corona treatment. . Birefringence ΔN was measured on the corona-treated surface.

(3.1.4) Example 4C
A laminate according to Example 4C was produced in the same manner as the laminate according to Example 1C, except that the following film F3 was used as the base layer and the following film F2 was used as the intermediate layer. Film F3 used as a base layer is a biaxially stretched film. This film F3 has a birefringence ΔN of 0.01513, a haze of 5.9%, a thickness of 25 μm, a density of 0.950 g/cm ³ , and is corona-treated on one side. . Film F2 used as an intermediate layer is a longitudinally uniaxially stretched film made of high-density polyethylene. This film F2 has a birefringence ΔN of 0.04121, a haze of 4.1%, a thickness of 25 μm, a density of 0.950 g/cm ³ , and one-sided corona treatment. . For any film, the birefringence ΔN was measured on the corona-treated surface.

(3.1.5) Example 5C
A laminate according to Example 5C was produced in the same manner as the laminate according to Example 1C, except that no gas barrier layer was provided.

(3.1.6) Example 6C
A laminate according to Example 6C was produced in the same manner as the laminate according to Example 1C except that the following film F4 was used as an intermediate layer. The film F4 used has a birefringence ΔN of 0.0051, a haze of 52.9%, a thickness of 40 μm, a density of 0.949 g/cm ³ , and one-sided corona treatment. there is Birefringence ΔN was measured on the corona-treated surface.

(3.1.7) Comparative Example 1C
A laminate according to Comparative Example 1C was produced in the same manner as the laminate according to Example 1C, except that the following film F4 was used as the base layer. The film F4 used has a birefringence ΔN of 0.0051, a haze of 52.9%, a thickness of 40 μm, a density of 0.949 g/cm ³ , and one-sided corona treatment. there is Birefringence ΔN was measured on the corona-treated surface.

(3.1.8) Comparative Example 2C
A laminate according to Comparative Example 2C was produced in the same manner as the laminate according to Example 1C, except that Film F4 below was used as the base layer and Film F4 below was used as the intermediate layer. The film F4 used has a birefringence ΔN of 0.0051, a haze of 52.9%, a thickness of 40 μm, a density of 0.949 g/cm ³ , and one-sided corona treatment. there is Birefringence ΔN was measured on the corona-treated surface.

(3.2) Evaluation method (3.2.1) Evaluation method for heat resistance at 140°C A sample piece of 10 cm x 10 cm was obtained by cutting out the laminate. The sample strip was then folded with the sealant layer on the inside and the sample strip was heat sealed. Heat sealing was performed by applying a temperature of 140° C. and a pressure of 0.1 MPa to the sample piece for 1 second. After that, the appearance of the sample piece was evaluated based on the following evaluation criteria.
A: The base layer was not melted, and there was no problem in appearance. B: The base layer was melted, and there was a problem in the appearance of the laminate.

(3.2.2) Method for evaluating heat resistance at 170°C A sample piece of 10 cm square was obtained by cutting the above laminate. The sample strip was then folded in half with the sealant layer on the inside. Next, the lower surface sealing temperature of the heat seal tester was fixed at 30° C., and the upper surface sealing temperature was set at 170° C., and a pressure of 0.2 MPa was applied to the sample piece folded in two for 1 second. Then, the presence or absence of melting of the sealing surface was observed, and it was also observed whether or not the area of the upper surface of the sample piece folded in two against which the heat seal bar was applied adhered to the heat seal bar. Heat resistance was evaluated based on the following evaluation criteria.
A: The upper surface of the sample piece did not adhere to the heat seal bar.
B: The upper surface of the sample piece adhered to the heat seal bar.

(3.2.3) Visibility evaluation method Regarding the above laminate, when the laminate is observed from the base layer side, whether or not the pattern displayed by the printed layer can be clearly seen is determined according to the following evaluation criteria. evaluated based on
A: The pattern displayed by the printed layer was clearly visible. B: The pattern displayed by the printed layer was blurred and thin.

(3.2.4) Measurement of puncture strength The puncture strength of the laminate was measured by the method described above. That is, the puncture strength of the laminate was measured according to the method specified in JIS Z1707:2019 "General Rules for Plastic Films for Food Packaging". Specifically, a needle having a diameter of 1 mm and a semi-circular tip was pierced into the laminate from the substrate layer side at a speed of 50 mm/min, and the maximum force until the needle penetrated was measured. This measurement was performed multiple times and the arithmetic mean of the maximum force was obtained as the puncture strength.

(3.2.5) Method for evaluating gas barrier properties The gas barrier properties of the laminate were evaluated. Specifically, for the laminate, the oxygen transmission rate (Oxygen Transmission Rate: OTR) at 30 ° C. and 70% relative humidity is measured, and whether or not this value exceeds 10 cc / (m ² · day · atm) Based on this, the gas barrier property was evaluated. The oxygen transmission rate was measured according to the method described in Appendix B of JIS K7126-2:2006.
A: The oxygen permeability was less than 10 cc/(m ² ·day·atm). B: The oxygen permeability was 10 cc/(m ² ·day·atm) or more.

(3.2.6) In-plane Measurement by X-ray Diffraction Method For each of the base layer and the intermediate layer used in the production of the above laminate, in-plane measurement by X-ray diffraction method was performed as described above. . It was examined whether sharp diffraction peaks corresponding to the (110) plane were obtained in the obtained diffraction pattern.

(3.3) Results The results of the above measurements and evaluations are shown in Table 3 below.

As shown in Table 3, the laminates in which the birefringence ΔN of the substrate layer was within the range of 0.01 to 0.1 all had good heat resistance and visibility. Moreover, all laminates in which the birefringence ΔN of both the base layer and the intermediate layer were within the range of 0.01 to 0.1 exhibited high puncture strength. On the other hand, all laminates in which the birefringence ΔN of the base material layer is less than 0.01 were insufficient in heat resistance and visibility. Also, the laminate in which the birefringence ΔN of both the base layer and the intermediate layer was less than 0.01 exhibited low puncture strength.

(4) Test D
(4.1) Production of laminate (4.1.0) Preparation of coating solution (Preparation of anchor coating agent)
Acrylic polyol and tolylene diisocyanate are mixed so that the number of NCO groups of tolylene diisocyanate is equal to the number of OH groups of acrylic polyol, and the total solid content (total amount of acrylic polyol and tolylene diisocyanate ) was diluted with ethyl acetate to 5% by mass. To the mixed solution after dilution, β-(3,4-epoxycyclohexyl)trimethoxysilane was further added so as to be 5 parts by mass with respect to the total amount of 100 parts by mass of the acrylic polyol and tolylene diisocyanate. An anchor coating agent was prepared by mixing.

(4.1.1) Example 1D
A laminate 10D shown in FIG. 4 was manufactured by the following method.
First, as the base material layer 2 and the intermediate layer 4, the following films were prepared. The prepared film consisted of polyethylene and had a birefringence ΔN of 0.0238, a haze of 1.6%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

After one surface of the substrate layer 2 was subjected to corona treatment, the coating solution for forming the protective layer was applied by gravure coating and dried to form a protective layer having a thickness of 0.5 μm.
Next, a pattern was printed on the other corona-treated surface of the substrate layer 2 using water-based flexographic ink to form a printed layer 5 .

Next, on one corona-treated surface of the intermediate layer 4, a 40 nm-thick inorganic compound layer composed of a silicon oxide (SiOx) deposited film is formed using an electron beam heating type vacuum deposition device, and further, The organic/inorganic film mixed solution was applied to form a coating layer having a thickness of 0.3 μm. Thus, a gas barrier layer 3 composed of an inorganic compound layer and a coating layer was formed.

Next, a urethane-based adhesive was applied onto the printed layer 5 to form a first adhesive layer 6A, and the intermediate layer 4 and the base material layer 2 were bonded together.

Next, a sealant layer 7 is prepared, and a urethane-based adhesive for dry lamination (Takelac A525/Takenate A52 manufactured by Mitsui Chemicals, Inc.) is applied on the gas barrier layer 3 to form a second adhesive layer 6B. The intermediate layer 4 and the sealant layer 7 were bonded together with the adhesive layer 3 and the second adhesive layer 6B interposed therebetween. A linear low-density polyethylene (LLDPE) film (60 μm thick) was used as the material for the sealant layer.

Thus, a laminate according to Example 1D was produced. FIG. 4 shows a schematic cross-sectional view of a laminate 10D according to Example 1D.

(4.1.2) Example 2D
A laminate according to Example 2D was produced in the same manner as the laminate according to Example 1D, except that the following films were used as the base material layer 2 and the intermediate layer 4 . The film used consisted of polyethylene and had a birefringence ΔN of 0.0119, a haze of 5.9%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

(4.1.3) Example 3D
A laminate according to Example 3D was produced in the same manner as the laminate according to Example 2D except that the protective layer 1 was not provided and the following film was used as the intermediate layer 4. The film used was made of polyethylene and had a birefringence ΔN of 0.0029, a haze of 21.5%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

(4.1.4) Comparative Example 1D
A laminate according to Comparative Example 1D was produced in the same manner as the laminate according to Example 2D except that the protective layer 1 was not provided and the following films were used as the base layer 2 and the intermediate layer 4. Created. The film used was made of polyethylene and had a birefringence ΔN of 0.0029, a haze of 21.5%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. Yes, one side corona treated.

(4.2) Evaluation method (4.2.1) Evaluation method for heat resistance at 140°C It was heat-sealed under conditions of 140° C., pressure of 0.1 MPa, and time of 1 second. The heat resistance was visually evaluated based on the following evaluation criteria.
A: No wrinkles on the surface, does not adhere to the seal bar B: Wrinkles on the surface, adheres to the seal bar.

(4.2.2) Method for evaluating heat resistance at 170°C and 190°C A sample piece of 10 cm square was obtained by cutting the above laminate. The sample strip was then folded in half with the sealant layer on the inside. Next, the lower surface sealing temperature of the heat seal tester was fixed at 30° C., and the upper surface sealing temperature was set at 170° C., and a pressure of 0.2 MPa was applied to the sample piece folded in two for 1 second. Then, the presence or absence of melting of the sealing surface was observed, and it was also observed whether or not the area of the upper surface of the sample piece folded in two against which the heat seal bar was applied adhered to the heat seal bar. Heat resistance was evaluated based on the following evaluation criteria.
A: The upper surface of the sample piece did not adhere to the heat seal bar.
B: The upper surface of the sample piece adhered to the heat seal bar.

(4.2.3) Evaluation Method for Visibility The laminate was visually observed, and the visibility of the printed layer from the substrate layer side was evaluated based on the following evaluation criteria.
A: The printed pattern is clearly visible. B: The printed pattern is blurred and looks thin.

(4.2.4) Measurement of puncture strength The puncture strength of the laminate was measured by the method described above.

(4.2.5) Recyclability Evaluation Method Regarding the above laminate, the mass ratio of polyethylene (PE) to the total mass of the laminate was calculated, and the recyclability was evaluated according to the following criteria.
A: Ratio of polyethylene 90% by mass or more B: Ratio of polyethylene less than 90% by mass.

(4.2.6) In-plane Measurement by X-ray Diffraction Method For each of the base layer and the intermediate layer used in the production of the above laminate, in-plane measurement by X-ray diffraction method was performed as described above. . It was examined whether sharp diffraction peaks corresponding to the (110) plane were obtained in the obtained diffraction pattern.

(4.3) Results Table 4 shows the results of the above evaluation.

As shown in Table 4, the laminates in which the birefringence ΔN of the base material layer was in the range of 0.01 to 0.1 all had good heat resistance and visibility. A laminate having a base layer with a birefringence ΔN in the range of 0.01 to 0.1 and having a protective layer was particularly excellent in heat resistance. In addition, the laminates in which the birefringence ΔN of both the base material layer and the intermediate layer were within the range of 0.01 to 0.1 and which had a protective layer exhibited high puncture strength. On the other hand, a laminate having a base material layer with a birefringence ΔN of less than 0.01 had insufficient heat resistance and visibility. Also, the laminate in which the birefringence ΔN of both the base layer and the intermediate layer was less than 0.01 exhibited low puncture strength.

(5) Test E
(5.1) Production of laminate (5.1.0) Preparation of film and preparation of coating liquid In the following examples and comparative examples, any one of the following α1 to α6 films is used as the resin layer containing polyethylene. board.
α1: thickness 25 μm, density 0.956 g/cm ³ , birefringence ΔN 0.04121
α2: thickness 30 μm, density 0.937 g/cm ³ , birefringence ΔN 0.01971
α3: thickness 35 μm, density 0.926 g/cm ³ , birefringence ΔN 0.00154
α4: thickness 32 μm, density 0.946 g/cm ³ , birefringence ΔN 0.00343
α5: thickness 35 μm, density 0.948 g/cm ³ , birefringence ΔN 0.00302
α6: thickness 60 μm, density 0.921 g/cm ³ , birefringence ΔN 0.00009.

(Preparation of mixed solution for pretreatment layer)
Acrylic polyol and tolylene diisocyanate are mixed so that the number of NCO groups of tolylene diisocyanate is equal to the number of OH groups of acrylic polyol, and the total solid content (total amount of acrylic polyol and tolylene diisocyanate ) was diluted with ethyl acetate to 5% by mass. Further, β-(3,4-epoxycyclohexyl)trimethoxysilane was added to 5 parts by mass with respect to 100 parts by mass of the total amount of the acrylic polyol and tolylene diisocyanate and mixed.
As described above, a mixed liquid for a pretreatment layer was obtained.

(Preparation of mixture for coating layer)
Liquid A, liquid B and liquid C shown below were mixed in a mass ratio of 70/20/10, respectively, to obtain a mixed liquid for an overcoat layer.
_A solution: Solid content 5% by mass ₍ _SiO ₂ equivalent) hydrolysis solution.
B solution: 5 mass % water/methanol solution of polyvinyl alcohol (mass ratio of water:methanol is 95:5).
Solution C: 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate was diluted with a mixture of water/isopropyl alcohol (mass ratio of water:isopropyl alcohol is 1:1) to a solid content of 5% by mass. Hydrolysis solution.

(Preparation of Adhesive for Adhesive Layer Formation)
Either of the following was used for the 1st adhesive bond layer and the 2nd adhesive bond layer.
(urethane adhesive)
Adhesive (gas barrier adhesive) obtained by mixing 100 parts by mass of Takelac A525 manufactured by Mitsui Chemicals, 11 parts by mass of Takenate A52 manufactured by Mitsui Chemicals, and 84 parts by mass of ethyl acetate
An adhesive obtained by mixing 16 parts by mass of Maxieve C93T manufactured by Mitsubishi Gas Chemical Co., Ltd. and 5 parts by mass of Maxibe M-100 manufactured by Mitsubishi Gas Chemical Co., Ltd. into 23 parts by mass of a solvent obtained by mixing ethyl acetate and methanol at a mass ratio of 1:1.

(5.1.1) Example 1E
As the intermediate layer 4, a resin film α3 was used. One surface of the intermediate layer 4 was subjected to plasma treatment using Ar gas at a treatment intensity of 100 W·sec/m ² . The treatment intensity was calculated as follows.
Power density [W/m ² ] = input power [W]/cathode area [m ² ]
Processing time [sec]=electrode MD width [m]/processing speed [m/sec]
Processing intensity = power density [W/m ² ] × processing time [sec]
On the other surface of the intermediate layer 4, the pretreatment layer mixture was applied in a coating amount of 0.1 g/m ² by gravure coating, dried and cured to form a pretreatment layer. An inorganic compound layer (thickness: 30 nm) made of silicon oxide (SiOx) was formed as a gas barrier layer 3 on the pretreatment layer using a vacuum vapor deposition apparatus using an electron beam heating method.

On the inorganic compound layer, a gas barrier adhesive was applied to form a second adhesive layer 6B with a thickness of 3 μm, and a resin film α6 was attached as a sealant layer 7.

A urethane-based adhesive is applied to the plasma-treated surface of the intermediate layer 4 by gravure coating and dried to form a first adhesive layer 6A having a thickness of 3 μm. Layer 2 was applied. After that, aging was performed at 40° C. for 4 days to produce a laminate according to Example 1E.

(5.1.2) Example 2E
A laminate according to Example 2E was produced in the same manner as in Example 1E, except that the resin film α2 was used as the base material layer 2 .

(5.1.3) Example 3E
A laminate according to Example 3E was produced in the same manner as in Example 1E, except that the resin film α4 was used as the intermediate layer 4 .

(5.1.4) Example 4E
A laminate according to Example 4E was obtained in the same manner as in Example 1E, except that the coating layer mixture was applied onto the inorganic compound layer by gravure coating and dried to form a coating layer having a thickness of 3 μm. made. In the laminate according to Example 4E, the gas barrier layer 3 consists of an inorganic compound layer and a coating layer.

(5.1.5) Example 5E
A laminate according to Example 5E was produced in the same manner as in Example 4E, except that the pretreatment layer was not provided.

(5.1.6) Example 6E
A laminate according to Example 6E was produced in the same manner as in Example 5E, except that no coating layer was provided.

(5.1.7) Example 7E
A laminate according to Example 7E was produced in the same manner as in Example 6E, except that the second adhesive layer 6B was formed from a urethane-based adhesive.

(5.1.8) Example 8E
A laminate according to Example 8E was produced in the same manner as in Example 6E, except that the film thickness of the inorganic compound layer was 10 nm.

(5.1.9) Example 9E
A laminate according to Example 9E was produced in the same manner as in Example 6E, except that the inorganic compound layer was an aluminum oxide (AlOx) layer (formed by electron beam deposition) having a thickness of 3 nm.

(5.1.10) Example 10E
Example 10E was prepared in the same manner as in Example 4E, except that the inorganic compound layer was an aluminum oxide (AlOx) layer (formed by electron beam evaporation) with a thickness of 9 nm and the second adhesive layer 6B was formed with a urethane-based adhesive. A laminate according to was produced.

(5.1.11) Example 11E
A laminate according to Example 11E was produced in the same manner as in Example 1E, except that the inorganic compound layer was an aluminum oxide (AlOx) layer (formed by electron beam deposition) having a thickness of 20 nm.

(5.1.12) Example 12E
A laminate according to Example 12E was produced in the same manner as in Example 6E, except that the inorganic compound layer was a metal aluminum (Al) layer (formed by electron beam deposition) having a thickness of 10 nm.

(5.1.13) Example 13E
The same procedure as in Example 6E, except that hexamethyldisiloxane (HMDSO) was introduced into the vacuum apparatus and an inorganic compound layer (thickness: 30 nm) made of silicon oxide containing carbon (SiOxCy) was formed by plasma CVD. to produce a laminate according to Example 13E.

(5.1.14) Example 14E
Monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ) were introduced into the vacuum chamber, and an inorganic compound layer (thickness: 30 nm) made of silicon nitride (SiNx) was formed by plasma CVD. A laminate according to Example 14E was produced in the same manner as in Example 6E, except that

(5.1.15) Example 15E
A laminate according to Example 15E was produced in the same manner as in Example 1E, except that the resin film α1 was used as the base material layer 2 and the intermediate layer 4 .

(5.1.16) Comparative Example 1E
A laminate according to Comparative Example 1E was produced in the same procedure as in Example 1E, except that the resin film α4 was used as the base material layer 2 .

(5.1.17) Comparative Example 2E
A laminate according to Comparative Example 2E was produced in the same manner as in Example 1E, except that the resin film α5 was used as the base layer 2 and the resin film α1 was used as the intermediate layer 4, respectively.

(5.2) Evaluation The following evaluation was performed on the laminate.

(5.2.1) Measurement for Acquiring Birefringence ΔN Measurement conditions and the like for calculating birefringence ΔN are shown below.
Apparatus: Phase difference measuring apparatus (manufactured by Oji Scientific Instruments Co., Ltd.: KOBRA-WR)
Light source wavelength: 586.6 nm
Measurement method: Parallel Nicol rotation method Directly above measurement.

(5.2.2) Evaluation of Tearability of Laminate Measured by the trouser method according to JIS K 7128-1. Measurements were taken in the direction in which one side of the rectangular laminate extends and in the direction perpendicular thereto, and the lower value was adopted. Those with a value of 100 N/mm or less were evaluated as "good tearability (A)", and those that exceeded 100N/mm or did not tear due to stretched laminate were evaluated as "poor tearability (B)". .

(5.2.3) Evaluation of Adhesion between Gas Barrier Layer and Intermediate Layer According to JIS Z1707, a 15 mm wide strip-shaped test piece was cut out from the above laminate, and tested using an Orientec Tensilon universal testing machine RTC-1250. was used to measure the laminate strength between the base material layer and the sealant layer. Those with a lamination strength of 1 N/15 mm or more, and those in which the laminate stretched and the base layer and the sealant layer could not be separated were evaluated as "good adhesion (A)", and those of less than 1 N/15 mm, It was evaluated as "poor adhesion (B)".

(5.2.4) Method for evaluating heat resistance at 170°C A sample piece of 10 cm square was obtained by cutting the above laminate. The sample strip was then folded in half with the sealant layer on the inside. Next, the lower surface sealing temperature of the heat seal tester was fixed at 30° C., and the upper surface sealing temperature was set at 170° C., and a pressure of 0.2 MPa was applied to the sample piece folded in two for 1 second. Then, the presence or absence of melting of the sealing surface was observed, and it was also observed whether or not the area of the upper surface of the sample piece folded in two against which the heat seal bar was applied adhered to the heat seal bar. Heat resistance was evaluated based on the following evaluation criteria.
A: The upper surface of the sample piece did not adhere to the heat seal bar.
B: The upper surface of the sample piece adhered to the heat seal bar.

(5.2.5) In-plane Measurement by X-ray Diffraction Method For each of the base layer and the intermediate layer used in the production of the above laminate, in-plane measurement by X-ray diffraction method was performed as described above. . It was examined whether sharp diffraction peaks corresponding to the (110) plane were obtained in the obtained diffraction pattern.

(5.3) Results Table 5 shows the results of the above evaluation. In the column of "tearability" in Table 5, "good tearability (A)" is indicated as "A", and "poor tearability (B)" is indicated as "B". In addition, in the column of "Adhesion" in Table 5, "Good adhesion (A)" is indicated as "A", and "Poor adhesion (B)" is indicated as "B".

As shown in Table 5, all laminates in which the birefringence ΔN of the substrate layer was in the range of 0.01 to 0.1 had good tear resistance and heat resistance. A laminate in which the birefringence ΔN of the substrate layer is in the range of 0.01 to 0.1 and the birefringence ΔN of the intermediate layer is less than 0.01 is excellent in tear resistance, heat resistance and adhesion. was On the other hand, all laminates in which the birefringence ΔN of the base material layer was less than 0.01 were poor in tear resistance and heat resistance.

(6) Test F
(6.1) Production of laminate (6.1.0) Preparation of coating liquid (Preparation of anchor coating agent)
Acrylic polyol and tolylene diisocyanate are mixed so that the number of NCO groups of tolylene diisocyanate is equal to the number of OH groups of acrylic polyol, and the total solid content (total amount of acrylic polyol and tolylene diisocyanate ) was diluted with ethyl acetate to 5% by mass. To the mixed solution after dilution, β-(3,4-epoxycyclohexyl)trimethoxysilane was further added so as to be 5 parts by mass with respect to the total amount of 100 parts by mass of the acrylic polyol and tolylene diisocyanate. An anchor coating agent was prepared by mixing.

(Preparation of coating liquid for coating layer formation)
An overcoat agent was prepared by mixing the following A liquid, B liquid, and C liquid at a mass ratio of 70/20/10, respectively.
_A solution: Solid content 5 _% by mass ₍ SiO ₂ equivalent) hydrolysis solution.
B solution: 5 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 with a mixture of water/isopropyl alcohol (mass ratio of water:isopropyl alcohol was 1:1) to a solid content of 5% by mass. Hydrolysis solution.

(6.1.1) Example 1F
A laminate 10F shown in FIG. 6 was manufactured by the following method.
First, as the base material layer 2, the following film F11 was prepared. The prepared film F11 was made of polyethylene and had a birefringence ΔN of 0.0238, a haze of 1.6%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. and is corona treated on one side.

Next, as the intermediate layer 4, the following film F12 was prepared. The prepared film F12 consisted of polyethylene and had a birefringence ΔN of 0.0029, a haze of 21.5%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. and is corona treated on one side.

Next, on one corona-treated surface of the intermediate layer 4, a 40 nm-thick inorganic compound layer composed of a silicon oxide (SiOx) deposited film is formed using an electron beam heating type vacuum deposition device. The inorganic film mixed solution was applied to form a coating layer having a thickness of 0.3 μm. Thus, a gas barrier layer 3 composed of an inorganic compound layer and a coating layer was formed.

Next, a urethane-based adhesive was applied onto the corona-treated surface of the substrate layer 2 to form a first adhesive layer 6A, and the intermediate layer 4 and the substrate layer 2 were bonded together.

Thus, a laminate according to Example 1F was produced. FIG. 6 shows a schematic cross-sectional view of a laminate 10F according to Example 1F.

(6.1.2) Example 2F
A laminate according to Example 2F was produced in the same manner as the laminate according to Example 1F, except that the following film F13 was used as the base material layer 2 . The film F13 used was made of polyethylene and had a birefringence ΔN of 0.0119 measured by the method described above, a haze of 5.9%, a thickness of 25 μm and a density of 0.950 g/cm ³ . and is corona treated on one side.

<Example 3F>
A laminate according to Example 3F was produced in the same manner as the laminate according to Example 2F, except that the protective layer 1 was not provided and the following film F13 was used as the intermediate layer 4. The film F13 used was made of polyethylene and had a birefringence ΔN of 0.0119 measured by the method described above, a haze of 5.9%, a thickness of 25 μm and a density of 0.950 g/cm ³ . and is corona treated on one side.

<Comparative Example 1F>
Same as the laminate according to Example 2F except that the protective layer 1 was not provided, the following film F12 was used as the base layer 2, and the following film F13 was used as the intermediate layer 4. A laminate according to Comparative Example 1F was created by the method of. The film F12 used was made of polyethylene and had a birefringence ΔN of 0.0029, a haze of 21.5%, a thickness of 25 μm and a density of 0.950 g/cm ³ as measured by the method described above. and is corona treated on one side. The film F13 used was made of polyethylene and had a birefringence ΔN of 0.0119 measured by the method described above, a haze of 5.9%, a thickness of 25 μm and a density of 0.950 g/cm ³ . and is corona treated on one side.

(6.2) Evaluation method (6.2.1) Heat resistance evaluation method at 140 ° C. Cut out a 10 cm square sample piece of the above laminate, fold it in half so that the sealant layer is on the inside, and use a heat seal tester. was used to perform heat sealing under the conditions of a temperature of 140° C., a pressure of 0.1 MPa, and a time of 1 second. The heat resistance was visually evaluated based on the following evaluation criteria.
A: The surface is not melted and there is no problem in appearance
B: The surface is melted and there is a problem in appearance.

(6.2.2) Method for evaluating heat resistance at 170°C and 190°C A sample piece of 10 cm square was obtained by cutting the above laminate. The sample strip was then folded in half with the sealant layer on the inside. Next, the lower surface sealing temperature of the heat seal tester was fixed at 30° C., and the upper surface sealing temperature was set at 170° C., and a pressure of 0.2 MPa was applied to the sample piece folded in two for 1 second. Then, the presence or absence of melting of the sealing surface was observed, and it was also observed whether or not the area of the upper surface of the sample piece folded in two against which the heat seal bar was applied adhered to the heat seal bar. Heat resistance was evaluated based on the following evaluation criteria.
A: The upper surface of the sample piece did not adhere to the heat seal bar.
B: The upper surface of the sample piece adhered to the heat seal bar.

(6.2.3) Evaluation Method for Visibility The laminate was visually observed, and the visibility of the printed layer from the substrate layer side was evaluated based on the following evaluation criteria.
A: The printed pattern is clearly visible. B: The printed pattern is blurred and looks pale.

(6.2.4) Method for evaluating drop strength Ten packaging bags of 100 mm x 150 mm with heat-sealed peripheral portions were produced using the above laminate. This packaging bag was filled with 200 ml of tap water, sealed by heat sealing, and stored at 5° C. for one day. After that, the packaging bag was dropped from a height of 1.5 m 50 times, and the number of broken packaging bags was recorded.

(6.2.5) Recyclability Evaluation Method Regarding the above laminate, the mass ratio of polyethylene (PE) to the total mass of the laminate was calculated, and the recyclability was evaluated according to the following criteria.
A: Ratio of polyethylene 90% by mass or more B: Ratio of polyethylene less than 90% by mass.

(6.2.6) In-plane Measurement by X-ray Diffraction Method For each of the base layer and the intermediate layer used in the production of the above laminate, in-plane measurement by X-ray diffraction method was performed as described above. . It was examined whether sharp diffraction peaks corresponding to the (110) plane were obtained in the obtained diffraction pattern.

(6.3) Results Table 6 shows the results of the above evaluation.

As shown in Table 6, the laminates in which the birefringence ΔN of the base material layer was within the range of 0.01 to 0.1 were all excellent in heat resistance and visibility. A laminate having a base layer with a birefringence ΔN in the range of 0.01 to 0.1 and having a protective layer was particularly excellent in heat resistance. Moreover, the laminate in which the birefringence ΔN of the base layer was in the range of 0.01 to 0.1 and the birefringence ΔN of the intermediate layer was less than 0.01 was excellent in drop strength. On the other hand, a laminate having a base material layer with a birefringence ΔN of less than 0.01 had insufficient heat resistance and visibility.

DESCRIPTION OF SYMBOLS 1... Protective layer 2... Base material layer 3... Gas barrier layer 4... Intermediate layer 5... Printing layer 6... Adhesive layer 6A... First adhesive layer 6B... Second adhesive layer 7... Sealant layer 10A Laminate 10B Laminate 10C Laminate 10D Laminate 10E Laminate 10F Laminate 100A Packaged article 100B Packaged article 100C Packaged article 110A Package, 110B... Package, 110C... Package, 110C1... Container body, 110C2... Mouth member, 110C3... Lid

Claims

comprising a substrate layer, an adhesive layer and a sealant layer in this order,
The base layer and the sealant layer comprise polyethylene,
The substrate layer is a laminate having a birefringence ΔN measured by a parallel Nicols rotation method within a range of 0.01 to 0.1.
The laminate according to claim 1, wherein the base material layer has the birefringence ΔN within the range of 0.01 to 0.052.
The laminate according to claim 1 or 2, further comprising an intermediate layer interposed between the base material layer and the sealant layer and containing polyethylene.
The laminate according to claim 3, wherein the intermediate layer has a birefringence ΔN measured by a parallel Nicols rotation method within a range of 0 to 0.01.
The laminate according to claim 3, wherein the intermediate layer has a birefringence ΔN measured by a parallel Nicols rotation method within a range of 0.01 to 0.1.
The laminate according to claim 5, wherein the intermediate layer has the birefringence ΔN within the range of 0.01 to 0.052.
The laminate according to any one of claims 1 to 6, further comprising a protective layer as an outermost layer facing the sealant layer with the base layer interposed therebetween.
The laminate according to claim 7, wherein the protective layer is made of a thermosetting resin.
The laminate according to any one of claims 1 to 8, wherein the base material layer is a biaxially stretched film.
The laminate according to any one of claims 1 to 8, wherein the base material layer is a uniaxially stretched film.
The laminate according to any one of claims 1 to 10, further comprising a gas barrier layer interposed between the base material layer and the sealant layer.
The laminate according to any one of claims 1 to 11, wherein the adhesive layer has gas barrier properties.
The laminate according to any one of claims 1 to 12, wherein the sealant layer is white.
The laminate according to any one of claims 1 to 13, wherein the proportion of polyethylene is 90% by mass or more.
A package containing the laminate according to any one of claims 1 to 14.
The package according to claim 15, which is a standing pouch.
A packaged article containing the package according to claim 15 or 16 and the contents accommodated therein.