Laminate, container forming sheet, and container

Abstract

The objective is to provide a laminate that has appropriate oxygen barrier properties for its contents without using expensive oxygen barrier materials. Furthermore, the present invention aims to provide a container-forming sheet and a container that can maintain oxygen barrier properties before and after container formation. [Solution] The present invention relates to a laminate comprising a base layer and surface layers provided on both sides of the base layer, wherein the base layer comprises a polyolefin resin, mica, and a dispersant, and the oxygen permeability coefficient of the base layer is 32,000 cm². 3 ·μm / (m 2 The present invention provides a laminate having an oxygen permeability of 24h·atm or less. The present invention also provides a container-forming sheet including the laminate and a container formed from the container-forming sheet. Furthermore, in the present invention, the oxygen permeability coefficient of the base layer in the container formed from the container-forming sheet may be lower than the oxygen permeability coefficient of the base layer in the sheet.

Description

[Technical Field]

[0001] This technology relates to laminates, sheets for forming containers, and containers. [Background technology]

[0002] Traditionally, in the field of food packaging technology, technologies have been developed that enable food to have a longer shelf life by preventing the deterioration of food quality and extending the shelf life, such as the best-before date or expiration date. For example, packaging materials with excellent gas barrier properties have attracted attention because they can properly prevent the permeation of gases from outside the packaging and maintain the stable quality of food. Among the gases that may permeate from outside the packaging, oxygen in particular is prone to causing oxidation, discoloration, deterioration of flavor, and growth of bacteria in food, so excellent oxygen barrier properties are desirable.

[0003] For example, Patent Document 1 discloses a technology relating to a product comprising a multilayer structure including an ethylene-vinyl alcohol copolymer having an ethylene unit content of 20 mol% to 60 mol%, a gas barrier layer having a specific thickness, and a thermoplastic resin layer made of polyolefin resin; a lid material for sealing the packaging container; and a gel-like content tightly filled in the sealed space, wherein the hardness of the packaging container, the hardness of the gel-like content, and the numerical range of their ratios are specified. This technology enables easy removal of the contents while maintaining a high level of quality in a packaging container with high gas barrier properties. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-158129

[0005] Currently, ethylene-vinyl alcohol copolymers are a prime example of oxygen barrier materials that account for a large portion of the market. However, many of these oxygen barrier materials are expensive and have unstable supply, limiting their applications in the food packaging sector. Therefore, there is a need for the development of oxygen barrier materials that offer suitable oxygen barrier performance and price range for food packaging applications, while also being readily available. [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to provide laminates, container-forming sheets, and containers that have appropriate oxygen barrier properties for their contents without using expensive oxygen barrier materials. Furthermore, the present invention aims to provide container-forming sheets and containers that can maintain oxygen barrier properties before and after container formation. [Means for solving the problem]

[0007] The present invention A laminate comprising a base layer and surface layers provided on both sides of the base layer, The substrate layer comprises a polyolefin resin, mica, and a dispersant. The oxygen permeability coefficient of the aforementioned substrate layer is 32,000 cm². 3 ·μm / (m 2 We provide a laminate that is less than or equal to 24 hours atm. The oxygen permeability coefficient of the aforementioned laminate is 33,000 cm². 3 ·μm / (m 2 It may be less than 24 hours (atm). In the laminate, the mica may be gold mica. In the laminate, the particle size of the mica can be 20 μm to 50 μm. In the laminate, the content of mica may be 30% to 50% by mass relative to the total amount of the base material layer. In the laminate, the dispersant may contain either or both of a fatty acid ester-based surfactant and modified polypropylene. In the laminate, the polyolefin resin may include polypropylene resin and polyethylene resin. Furthermore, the present invention also provides a container-forming sheet that includes the laminate. The oxygen permeability coefficient of the base material layer in a container formed from the container-forming sheet may be lower than that of the oxygen permeability coefficient of the base material layer in the container-forming sheet. Furthermore, the present invention also provides a container formed using the container-forming sheet. The oxygen permeability coefficient of the substrate layer in the aforementioned container is 29000 cm². 3 ·μm / (m 2 It may be less than 24 hours (atm). The oxygen permeability coefficient of the aforementioned container is 31,000 cm². 3 ·μm / (m 2 It may be less than 24 hours (atm). The oxygen permeability coefficient of the base material layer in a container formed from the container-forming sheet may be lower than that of the oxygen permeability coefficient of the base material layer in the container-forming sheet. [Effects of the Invention]

[0008] The present invention makes it possible to provide laminates, container-forming sheets, and containers that have appropriate oxygen barrier properties for their contents without using expensive oxygen barrier materials. Furthermore, the present invention can provide laminates, container-forming sheets, and containers that can maintain oxygen barrier properties before and after container formation. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing an example of the structure of a laminate according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram showing one embodiment of the method for manufacturing a laminate and a sheet for forming a container according to the present invention. [Modes for carrying out the invention]

[0010] Hereinafter, preferred embodiments of the present invention will be described. Note that the embodiments described below show typical embodiments of the present technology, and the scope of the present invention is not limited to only these embodiments. Also, in this specification, "X to Y" indicating a range includes the numerical values X and Y before and after it, and means "X or more and Y or less". Further, the upper limit value (hereinafter) and the lower limit value (above) of each numerical range (~) can be arbitrarily combined as desired.

[0011] The present invention will be described in the following order. 1. First Embodiment (Examples of Laminated Body and Sheet for Forming Container) (1) Configuration of Laminated Body (2) Manufacturing Method of Laminated Body (3) Physical Properties 2. Second Embodiment (Examples of Container) (1) Configuration of Container (2) Manufacturing Method of Container (3) Physical Properties 3. Examples

[0012] 1. First Embodiment (Examples of Laminated Body and Sheet for Forming Container) The laminated body and the sheet for forming a container according to the first embodiment of the present invention can be, for example, a laminated body and a sheet for forming a container used for food containers (for example, food packaging containers, the container body of food containers, the body of beverage containers, and their lids, etc.). Note that all of the descriptions of the laminated body according to the first embodiment of the present invention described below also apply to the sheet for forming a container according to the first embodiment of the present invention. Therefore, the description of the sheet for forming a container will be omitted.

[0013] The laminated body according to the first embodiment of the present invention is a laminated body including a base material layer and surface layers provided on both surfaces of the base material layer, wherein the base material layer contains a polyolefin resin, mica, and a dispersant, and the oxygen permeability coefficient of the base material layer is 32000 cm 3 ·μm / (m 2The temperature is below 24 hours atm. Furthermore, this configuration makes it possible to achieve appropriate oxygen barrier properties for the contents without using expensive oxygen barrier materials. (1) Structure of the laminate Figure 1 is a cross-sectional view showing an example of the structure of a laminate according to the first embodiment of the present invention. The laminate 100 according to the first embodiment of the present invention is composed of a base layer 101 containing a polyolefin resin, mica, and a dispersant, and surface layers 102 and 103 provided on both sides of the base layer 101 (hereinafter referred to as the first surface layer and the second surface layer, respectively). The two surface layers 102 and 103 may be formed from the same material or from different materials. The structure of the laminate according to the present invention will be described in more detail below.

[0014] <Base material layer> The substrate layer comprises a polyolefin resin, mica, and a dispersant, and has an oxygen permeability coefficient of 32,000 cm². 3 ·μm / (m 2 (24 hours / atm) or less.

[0015] (Polyolefin resin) Polyolefin resins are polymers obtained by polymerization using olefins (e.g., α-olefins) as the main monomers. These polyolefin resins may be, for example, polypropylene (PP) resins, polyethylene (PE) resins, or combinations thereof. Furthermore, these polyolefin resins may be, for example, homopolymers of homopolymers, copolymers of multiple types of olefins, or copolymers of olefins with other monomers. Examples of copolymers of multiple types of olefins, or of olefins with other monomers, include block copolymers, random copolymers, or combinations thereof.

[0016] The polyolefin resin used in the present invention is preferably an α-olefin resin, more preferably one or more polypropylene resins or polyethylene resins, and even more preferably a polypropylene resin and a polyethylene resin.

[0017] Examples of polypropylene resins include propylene homopolymers (homopolypropylene) and copolymers of propylene with other monomers, such as block copolymers (block polypropylene) or random copolymers (random polypropylene). From the viewpoint of ensuring container rigidity, the polypropylene resin used in the present invention preferably contains at least a polypropylene homopolymer (homopolypropylene).

[0018] If the polyolefin resin includes homopolypropylene, the density of the homopolypropylene (g / cm³) 3 For example, 0.880 g / cm³ 3 More than 0.920g / cm 3 The following may be true, preferably 0.885 g / cm³ 3 More than 0.915g / cm 3 The following, and more preferably 0.890 g / cm³ 3 More than 0.910g / cm 3 The following applies:

[0019] When the polyolefin resin includes homopolypropylene, the melt flow rate (MFR) of the homopolypropylene may be, for example, 0.1 g / 10 min or more and 5.0 g / 10 min or less, preferably 0.2 g / 10 min or more and 4.0 g / 10 min or less, more preferably 0.3 g / 10 min or more and 3.5 g / 10 min or less, and even more preferably 0.3 g / 10 min or more and 3.0 g / 10 min or less. The MFR of the homopolypropylene is a value measured in accordance with JIS K7210 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0020] When the polyolefin resin includes homopolypropylene, the flexural modulus (MPa) of the homopolypropylene may be, for example, 1000 MPa or more and 2000 MPa or less, preferably 1050 MPa or more and 1950 MPa or less, and more preferably 1100 MPa or more and 1900 MPa or less. The flexural modulus of the homopolypropylene is a value measured in accordance with JIS K7171.

[0021] Examples of polyethylene resins include low-density polyethylene (LDPE), high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), or ultra-high molecular weight polyethylene (UHMW-PE), or combinations thereof. From the viewpoint of oxygen barrier properties and thermoformability, the polyethylene-based resin used in this technology preferably contains at least high-density polyethylene (HDPE).

[0022] If the polyolefin resin includes high-density polyethylene resin, the density of the high-density polyethylene resin (g / cm³) 3 For example, 0.930 g / cm³ 3 More than 0.970g / cm 3 It may be less than or equal to the following, preferably 0.935 g / cm³ 3 More than 0.967g / cm 3 The following, and more preferably 0.940 g / cm³ 3 More than 0.964g / cm 3 The following applies:

[0023] When the polyolefin resin includes high-density polyethylene resin, the MFR of the high-density polyethylene resin may be, for example, 0.05 g / 10 min or more and 5.0 g / 10 min or less, preferably 0.1 g / 10 min or more and 4.0 g / 10 min or less, and more preferably 0.15 g / 10 min or more and 3.5 g / 10 min or less. The MFR of the high-density polyethylene resin is a value measured in accordance with JIS K6922-2 under conditions of a temperature of 190°C and a load of 2.16 kg.

[0024] When the polyolefin resin includes high-density polyethylene resin, the flexural modulus (MPa) of the high-density polyethylene resin may be, for example, 700 MPa or more and 1700 MPa or less, preferably 900 MPa or more and 1650 MPa or less, and more preferably 1100 MPa or more and 1600 MPa or less. The flexural modulus of the high-density polyethylene resin is a value measured in accordance with JIS K6922-2.

[0025] When the polyolefin resin includes a combination of homopolypropylene resin and high-density polyethylene resin, the mass ratio of homopolypropylene to high-density polyethylene (homopolypropylene:high-density polyethylene) is not particularly limited, but may be, for example, 50:50 to 90:10, preferably 55:45 to 85:15, and more preferably 60:40 to 80:20.

[0026] The polyolefin resin content in this invention can be freely set as long as it does not impair the problems and effects of this technology. However, from the viewpoint of the oxygen barrier properties of the laminate, the upper limit is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less, based on 100% by mass of the base layer. Furthermore, from the viewpoint of the processability of the laminate, the lower limit is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 45% by mass or more. The above upper and lower limits can be arbitrarily combined, but the range of polyolefin resin content is preferably 30% by mass or more and 90% by mass or less, more preferably 40% by mass or more and 80% by mass or less, and even more preferably 45% by mass or more and 75% by mass or less, based on 100% by mass of the base layer.

[0027] (Mica) The mica used in this invention is a silicate mineral containing silicon (Si), aluminum (Al), magnesium (Mg), potassium (K), sodium (Na), iron (Fe), etc., also known as mica. Mica is formed by multiple layers of sheet-like framework layers composed of Si and Al (or Mg) oxides and K ion layers, and has a plate-like crystalline structure with uniform particle size. By including mica having such a plate-like crystalline structure in the base layer of the laminate of this invention, excellent oxygen barrier properties are achieved. Specifically, because mica having a plate-like crystalline structure with uniform particle size tends to be oriented to take a stacked structure parallel to the thickness direction of the laminate, oxygen in the laminate cannot travel straight through the stacked structure formed by the mica and must bypass the parallel layers to permeate, and as a result, oxygen permeation is suppressed.

[0028] Any known type of mica can be used as long as it does not impair the challenges and effects of this technology. It may be natural mica obtained by wet or dry grinding of natural ore mica, or it may be synthetic mica obtained by melting high-purity raw materials at about 1°C high temperature, cooling and crystallizing them. Examples of natural mica include muscovite, phlocopite, sericite, and biotite, while examples of synthetic mica include fluorinated phlophtite, potassium tetrasilicate, sodium tetrasilicate, sodium teniolite, and lithium teniolite, and two or more of these may be included. Among these, white mica or gold mica is preferred from the viewpoint of oxygen barrier properties. White mica is mainly composed of aluminum oxide and has high hardness, while gold mica is mainly composed of magnesium oxide and is softer than white mica, and its plate-like structure is prone to peeling under lateral stress. From the viewpoint of oxygen barrier properties after molding, gold mica is more preferable. The softness of gold mica provides thermal stability during molding, making it possible to maintain oxygen barrier properties after molding.

[0029] The average particle size of mica in this invention can be freely set as long as it does not impair the problems and effects of this technology. However, from the viewpoint of oxygen barrier properties, the upper limit is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. From the viewpoint of mica dispersibility, the lower limit of the average particle size of mica is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. The above upper and lower limits can be arbitrarily combined, but the range of the average particle size of mica is preferably 5 μm or more and 50 μm or less, more preferably 20 μm or more and 50 μm or less, even more preferably 10 μm or more and 40 μm or less, and even more preferably 15 μm or more and 30 μm or less. The average particle size of mica can be measured, for example, by a laser diffraction particle size distribution analyzer.

[0030] The true specific gravity of mica in this invention is not particularly limited, but from the viewpoint of mica dispersion stability, it is preferably 2.6 to 3.2, more preferably 2.7 to 3.1, and even more preferably 2.8 to 3.0.

[0031] The mica content in this invention can be freely set as long as it does not impair the problems and effects of this technology. However, from the viewpoint of the mechanical strength of the laminate, the upper limit is preferably 65% ​​by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less, based on 100% by mass of the base layer. Furthermore, from the viewpoint of oxygen barrier properties, the lower limit is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and even more preferably 30% by mass or more. The above upper and lower limits can be combined arbitrarily, but the range of mica content is preferably 15% by mass or more and 65% by mass or less, more preferably 20% by mass or more and 60% by mass or less, even more preferably 25% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less, based on 100% by mass of the base layer.

[0032] (Dispersant) The dispersant in the present invention is not particularly limited and can be freely selected as long as it is compatible with the polyolefin resin and improves the dispersibility of mica in the substrate layer. Examples of dispersants in the present invention include nonionic surfactants, carboxylic acid derivatives, metal ionic fatty acids, modified polypropylene, etc., one or more of which can be used in combination. Examples of nonionic surfactants include fatty acid ester surfactants, such as glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, ethylene glycol fatty acid esters, etc. Examples of carboxylic acid derivatives include acid anhydrides, esters, amides, and imides of carboxylic acids such as acetic acid, (meth)acrylic acid, maleic acid, and fumaric acid. Examples of metal ionic fatty acids include zinc stearate, magnesium stearate, lithium stearate, calcium stearate, zinc phosphate, magnesium phosphate, lithium phosphate, and calcium phosphate. Examples of modified polypropylene include acid-modified polypropylene, which is obtained by acid-modifying polypropylene resin with an unsaturated carboxylic acid such as maleic acid or maleic anhydride, and hydroxy-modified polypropylene, which is obtained by introducing hydroxyl groups into polypropylene resin. As the polypropylene resin components of modified polypropylene are as described above, a detailed explanation will be omitted. Among these, modified polypropylene is preferred from the viewpoint of compatibility with polyolefin resins and oxygen barrier properties.

[0033] The dispersant content in this invention can be freely set as long as it does not impair the problems and effects of this technology. However, from the viewpoint of the mechanical strength of the laminate and compatibility with the polyolefin resin, the upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 13% by mass or less, based on 100% by mass of the base layer. Furthermore, from the viewpoint of the dispersibility of mica, the lower limit is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The above upper and lower limits can be combined arbitrarily, but the range of dispersant content is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 13% by mass or less, based on 100% by mass of the base layer.

[0034] (Other ingredients) The substrate layer in the present invention may contain other components besides those described above, as long as they do not impair the problems or effects of this technology. Examples of other components include resins other than polyolefin resins, inorganic fillers other than mica, colorants, nucleating agents, plasticizers, mold release agents, antioxidants, ultraviolet absorbers, antistatic agents, color inhibitors, etc., and one or more of these can be used in combination as needed.

[0035] (Oxygen permeability coefficient) In the present invention, the base material layer preferably has barrier properties suitable for the application due to the above configuration. Specifically, the upper limit of the oxygen permeability coefficient of the base material layer of the laminate according to the present invention is 32,000 cm². 3 ·μm / (m 2 It is preferable that the temperature is 24 hours (atm) or less, and 31,000 cm². 3 ·μm / (m 2 It is more preferable that the temperature is 24 hours (atm) or less, and 30,000 cm². 3 ·μm / (m 2 It is even more preferable that the oxygen permeability coefficient is less than or equal to 24h·atm. In this invention, the oxygen permeability coefficient is measured by the measurement method described later.

[0036] <Surface layer> The surface layer in the present invention can be freely selected depending on the application of the laminate. The surface layer may contain one or more of the following: for example, olefin resins, polystyrene resins, and polyester resins. From the viewpoint of moldability, it is preferable to use polyolefin resins for the surface layer, and more preferable to use polypropylene. Specific polyolefin resins are as described above. The surface layer in the present invention may contain other components besides those described above, as needed. Other components are as described above. Furthermore, as mentioned above, the two surface layers may be composed of different compositions, and their thicknesses may be the same or different. In addition, another layer may be provided on top of the two surface layers.

[0037] (2) Method for manufacturing the laminate The method for manufacturing a laminate according to the present invention may include, for example, a resin composition preparation step (S1) and a multilayer extrusion molding step (S2). Each step will be described below.

[0038] <Resin composition preparation process (S1)> In this process, the materials constituting the base layer and the surface layers provided on both sides of the base layer are mixed to prepare the resin compositions that make up each layer.

[0039] In the resin composition preparation process for the base layer, the resin composition (hereinafter referred to as the polyolefin resin composition) may contain polyolefin resin, mica, a dispersant, and other components as needed. Furthermore, in the resin composition preparation process for each surface layer, the compositions (hereinafter referred to as the first resin composition and the second resin composition) may contain, for example, polyolefin resin and other components as needed. Each resin composition is heated and mixed at a temperature of 300°C or lower. In this process, the raw materials for the components constituting each resin composition may be mixed first, and then the mixed raw materials may be heated and kneaded.

[0040] In the kneading step, the resin composition may be heated to a temperature at which, for example, the polyolefin resin can melt. Specifically, the kneading may be carried out at a temperature preferably above the melting point of the polypropylene resin, more preferably above 180°C, and even more preferably above 200°C. Alternatively, the kneading may be carried out at a temperature preferably below 300°C, more preferably below 280°C, and even more preferably below 260°C. If a nucleating agent is used as another component, the temperature may be appropriately selected by a person skilled in the art depending on the type and proportion of the nucleating agent.

[0041] The mixing of polyolefin resin and other components may be carried out using a mixer such as a high-temperature stirrer, Henschel mixer, tumbler mixer, Banbari mixer, or kneader mixer. The heating and kneading of the mixed raw materials may be carried out using a single-screw kneading extruder or a twin-screw kneading extruder, for example. Equipment known in the art may be used as these kneading extruders. Preferably, the above step includes at least heating and kneading treatment using a single-screw kneading extruder. By performing kneading treatment with a single-screw kneading extruder, a polyolefin resin composition can be obtained, which is a kneaded product in which the raw materials are more uniformly dispersed.

[0042] The polyolefin resin composition, which is the kneading product obtained in the above process, may be subjected directly to the multilayer extrusion molding process without being pelletized. This eliminates the need for the pelletizing process. The polyolefin resin composition obtained in the above process may be pelletized. The pelletized polyolefin resin composition may then be used in a sheet molding process.

[0043] <Multilayer extrusion process (S2)> In the multilayer extrusion process, a first resin composition, a polyolefin resin composition, and a second resin composition are extruded and molded so that the resin layers are stacked on top of each other to obtain a laminate. Figure 2 is a schematic diagram showing one embodiment of the method for manufacturing a laminate and a sheet for forming a container according to the present invention. The laminate can be obtained, for example, using the multilayer co-extrusion molding machine 300 shown in Figure 2. The multilayer co-extrusion molding machine 300 may have an extruder 301 for the first surface layer, an extruder 302 for the base layer, an extruder 303 for the second surface layer, a feed block 304, and a die 305. The multilayer co-extrusion molding machine 300 co-extrudes a three-layer laminate 306 in which the first surface layer, the base layer, and the second surface layer are stacked, with the base layer containing the polyolefin resin composition as the middle layer and the first surface layer and the second surface layer as the outer layers. The base layer extruder 302 extrudes the polyolefin resin composition prepared in the resin composition preparation step, and the first surface layer extruder 301 and the second surface layer extruder 303 may each extrude a different type of resin composition from the polyolefin resin composition extruded from the base layer extruder 302, or they may extrude the same polyolefin resin composition.

[0044] (3) Physical properties The physical properties of the laminate according to this embodiment will be described below.

[0045] <Oxygen permeability coefficient of the substrate layer (for laminates and container forming sheets)> In the laminate and container-forming sheet of the present invention, in measuring the oxygen permeability coefficient of the base material layer, first, the first and second surface layers are made of a material with a known oxygen permeability coefficient (oxygen permeability coefficient Scm 3 ·μm / (m 2 Prepare a sample using 24h·atm. Then, using a microscope, confirm the thickness A (μm) of the first surface layer of the laminate, the thickness B (μm) of the substrate layer, and the thickness C (μm) of the second surface layer, and calculate the ratio of each layer thickness. Next, the oxygen permeability of the sample is measured using the new gas permeability meter "K-315N-01" (manufactured by Toyo Rika Co., Ltd.) on the laminate, according to the pressure method specified in JIS K 7126-1 and ASTM D 1434M standards. The oxygen permeability obtained from the measurement is Dcm. 3 / (m 2 Let it be (24h·atm). Then, using A, B, C, D, and S, the oxygen permeability coefficient Ecm per 1 μm of the sheet substrate layer is calculated. 3 ·μm / (m 2 The value of (24 hours at an ATM) is calculated using the following formula 1.

[0046]

number

[0047] Furthermore, when different materials are used for the first and second surface layers (oxygen permeability coefficient Lcm of the first surface layer) 3 ·μm / (m 2 (24h·atm), oxygen permeability coefficient of the second surface layer Mcm 3 ·μm / (m 2 (·24h·atm) is the oxygen permeability coefficient E'cm per 1 μm of the sheet substrate layer. 3 ·μm / (m 2 The value of (24 hours at an ATM) is calculated using the following formula 2.

[0048]

number

[0049] <Oxygen permeability coefficient of laminated material> In the present invention, the oxygen permeability coefficient of the laminate represents the oxygen permeability coefficient of the entire laminate. In the laminate of the present invention, the oxygen permeability coefficient of the laminate is 33,000 cm². 3 ·μm / (m 2 It is preferable that the temperature is 24 hours (atm) or less, and 32,000 cm². 3 ·μm / (m 2 It is more preferable that the temperature is 24 hours (atm) or less, and 31,000 cm². 3 ·μm / (m 2 It is even more preferable that the operating hours are 24 hours or less (atm).

[0050] The oxygen permeability coefficient of the laminate in this invention can be calculated, for example, from the oxygen permeability of the laminate. Specifically, as described above, the oxygen permeability of the laminate is measured using the new gas permeability meter "K-315N-01" (manufactured by Toyo Rika Co., Ltd.) on the laminate by the pressure method specified in JIS K 7126-1 and ASTM D 1434M standards. The oxygen permeability coefficient of the laminate can be calculated from the oxygen permeability obtained by measurement and the thickness of the laminate.

[0051] 2. Second Embodiment (Example of a Container) A container according to the second embodiment of the present invention is a container (for example, a food container) obtained from a laminate or container-forming sheet according to the first embodiment of the present invention. With this configuration, a container with suitable oxygen barrier properties can be realized without using expensive oxygen barrier materials.

[0052] (1) Container composition The description of the container configuration according to the second embodiment of the present invention is the same as the description of the configuration of the laminate and container-forming sheet according to the first embodiment of the present invention described in 1.(1) above, so the description of the container configuration is omitted.

[0053] (2) Method of manufacturing containers A method for manufacturing a container according to a second embodiment of the present invention may include, for example, a resin composition preparation step (S1), a multilayer extrusion molding step (S2), and a container body molding step (S3). Note that the resin composition preparation step (S1) and the multilayer extrusion molding step (S2) are the same as those in the first embodiment, so their explanation will be omitted. The container body molding step (S3) will be described below.

[0054] <Container body forming process (S3)> In this process, the laminate (sheet) obtained in the multilayer extrusion process (S2) is softened by heating, and the softened sheet is brought into close contact with the molding die by suction to vacuum form the recess in which the packaged goods will be contained, thereby forming the container body. Vacuum forming or vacuum pressure forming is used as the molding method. Plug assist is also performed according to the expansion ratio. The depth of the recess can be set appropriately according to the application, for example, the depth of the recess may preferably be 1 to 5 cm. Deep drawing molding with an expansion ratio of 2.5 or higher may also be used. The sheet surface temperature inside the molding machine immediately before molding, measured with a non-contact infrared thermometer, is preferably heated to 140°C to 170°C, the heating time is preferably set to 6 to 15 seconds, and the molding time may preferably be set to 6 to 15 seconds. The optimal sheet surface temperature is selected from the viewpoint of the thickness balance of multi-cavity containers, etc.

[0055] (3) Physical properties The physical properties of the container according to this embodiment will be described below.

[0056] <Oxygen permeability coefficient of the substrate layer (container)> In the container of the present invention, when measuring the oxygen permeability coefficient of the base material layer, first, the thickness of each layer in the molded product (container) is calculated. Specifically, when measuring the side surface of the container, the side surface of the molded product with a magnification of approximately 3.7 is sampled, and if the side surface thickness is F, the thickness of each layer is calculated as follows. Thickness of the first surface layer: G = A × {F ÷ (A + B + C)} Thickness of the base layer: H = B × {F ÷ (A + B + C)} Thickness of the second surface layer: I = C × {F ÷ (A + B + C)} Oxygen permeability on the side of the container (Jcm) 3 / (m 2At 24 hours (atm), the oxygen permeability coefficient per 1 μm of the container side substrate layer is Kcm. 3 ·μm / (m 2 The value of (24 hours at an ATM) is calculated using formula 3 below.

[0057]

number

[0058] Furthermore, when different materials are used for the first and second surface layers (oxygen permeability coefficient Lcm of the first surface layer) 3 ·μm / (m 2 (24h·atm), oxygen permeability coefficient of the second surface layer Mcm 3 ·μm / (m 2 (·24h·atm) is the oxygen permeability coefficient K'cm per 1 μm of the container side substrate layer. 3 ·μm / (m 2 The value of (24 hours at an ATM) is calculated using the following formula 4.

[0059]

number

[0060] The substrate layer of the container of the present invention preferably has barrier properties suitable for its application. The upper limit of the oxygen permeability coefficient of the substrate layer of the container of the present invention is, for example, 49,000 cm². 3 ·μm / (m 2 It may be less than 24 hours (atm). Among these, from the perspective of maintaining oxygen barrier properties before and after container formation, 29,000 cm² is considered appropriate. 3 ·μm / (m 2 Preferably, it should be 24 hours (atm) or less, and 28,500 cm². 3 ·μm / (m 2 It is more preferable that the temperature is 24 hours (atm) or less, and 28,000 cm². 3 ·μm / (m 2 It is even more preferable that the operating hours are 24 hours or less (atm).

[0061] <Oxygen permeability coefficient of containers> In this invention, the oxygen permeability coefficient of the container represents the oxygen permeability coefficient of the entire container. In the container of this invention, the upper limit of the oxygen permeability coefficient of the container is, for example, 49,000 cm³. 3 ·μm / (m 2 It may be less than 24 hours (atm). Among these, from the perspective of maintaining oxygen barrier properties before and after container formation, 31,000 cm³ is considered appropriate. 3 ·μm / (m 2 Preferably, the temperature should be 24 hours (atm) or less, and 30,000 cm². 3 ·μm / (m 2 It is more preferable that the temperature is 24 hours (atm) or less, and 29,000 cm². 3 ·μm / (m 2 It is even more preferable that the oxygen permeability coefficient of the container of the present invention is less than or equal to 24h·atm. The method for measuring the oxygen permeability coefficient of the container of the present invention is the same as that for the laminate described above.

[0062] <Difference in oxygen permeability coefficient of the substrate layer before and after container formation> In the container of the present invention, it is preferable that the oxygen permeability coefficient of the base layer in the container formed from the container-forming sheet is lower than that of the base layer in the container-forming sheet. This tendency ensures that the oxygen barrier properties of the laminate of the present invention are not impaired even after the container formation process, and that the container of the present invention achieves oxygen barrier properties suitable for its intended use. The difference in the oxygen permeability coefficient of the base layer before and after container formation is calculated using the following formula 5.

[0063]

number

[0064] The present invention can also employ the following configuration. [1] A laminate comprising a base layer and surface layers provided on both sides of the base layer, The substrate layer comprises a polyolefin resin, mica, and a dispersant. The oxygen permeability coefficient of the aforementioned substrate layer is 32,000 cm². 3 ·μm / (m 2A laminate that is less than 24 hours (atm). [2] The oxygen permeability coefficient of the aforementioned laminate is 33,000 cm². 3 ·μm / (m 2 The laminate described in [1] is less than or equal to 24 hours atm. [3] The laminate according to [1] or [2], wherein the mica is gold mica. [4] The laminate according to any one of [1] to [3], wherein the particle size of the mica is 20 μm to 50 μm. [5] The laminate according to any one of [1] to [4], wherein the content of the mica is 30% to 50% by mass relative to the total amount of the base material layer. [6] The laminate according to any one of [1] to [5], wherein the dispersant comprises either or both a fatty acid ester surfactant and modified polypropylene. [7] The laminate according to any one of [1] to [6], wherein the polyolefin resin comprises a polypropylene resin and a polyethylene resin. [8] A sheet for forming a container, comprising a laminate described in any of [1] to [7]. [9] The container-forming sheet according to [8], wherein the oxygen permeability coefficient of the base material layer in a container formed from the container-forming sheet is lower than the oxygen permeability coefficient of the base material layer in the container-forming sheet.

[10] A container formed using the container-forming sheet described in [8] or [9].

[11] The oxygen permeability coefficient of the substrate layer in the aforementioned container is 29,000 cm². 3 ·μm / (m 2 The container described in

[10] is below 24 hours (atm).

[12] The oxygen permeability coefficient of the aforementioned container is 31,000 cm². 3 ·μm / (m 2 The containers described in

[10] or

[11] are below 24 hours (atm).

[13] A container according to any one of

[10] to

[12] , wherein the oxygen permeability coefficient of the base layer in a container formed from the container-forming sheet is lower than the oxygen permeability coefficient of the base layer in the container-forming sheet.

[0065] 3. Examples Next, the present invention will be described with reference to examples. The examples described below are representative examples of the present invention, and the scope of the present invention is not limited to these examples.

[0066] (Example 1) Polypropylene resin (product name: Novatec® FY6, manufactured by Nippon Polypropylene Co., Ltd., oxygen permeability coefficient S: 50720 cm) is injected into the first surface layer single-screw extruder 301 of the multilayer co-extrusion molding machine 300 (manufactured by LAB TECH Engineering Co., Ltd.) via a hopper (not shown). 3 ·μm / (m 2 A 24h·atm solution is supplied to the first resin composition at 100% by mass, and polypropylene resin (product name: Novatec® EA9, manufactured by Nippon Polypropylene Co., Ltd.) is supplied to the single-screw extruder 302 for the base layer via a hopper at 48.8% by mass relative to 100% by mass of the base layer, polyethylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.) at 20.9% by mass, fatty acid ester surfactant (product name: Tirabazole D-818M, manufactured by Taiyo Kagaku Co., Ltd.) at 0.3% by mass, and gold mica (product name: S-400, particle size 20 μm, manufactured by Repco) at 30% by mass, and then the mixture is supplied to the single-screw extruder 303 for the second surface layer. Polypropylene resin (product name: Novatec® FY6, manufactured by Nippon Polypropylene Co., Ltd.) was supplied via a hopper in an amount of 100% by mass relative to 100% by mass of the second resin composition. The resin compositions supplied to the first surface layer single-screw extruder, the base layer single-screw extruder, and the second surface layer single-screw extruder were co-extruded, cooled in a three-roll take-up machine (not shown) with each roll temperature of 40-90°C, and film was formed at a take-up speed of 0.7 m / min to obtain a three-layer sheet with a sheet width of 350 mm.

[0067] In addition, the cylinder temperature and adapter temperature of the single-screw extruder 301 (L / D = 30, φ25 mm) for the first surface layer, the single-screw extruder 302 (L / D = 30, φ25 mm) for the base material layer, and the single-screw extruder 303 (L / D = 30, φ25 mm) for the second surface layer were each set to 220 to 250°C. Also, the discharge rate of the single-screw extruder 302 for the base material layer was set to 10 kg / h, and the discharge rate of each of the single-screw extruder 301 for the first surface layer and the single-screw extruder 303 for the second surface layer was set to 1 kg / h. The resin temperature of each was 227°C for the single-screw extruder 301 for the first outer layer, 228°C for the single-screw extruder 302 for the base material layer, and 224°C for the single-screw extruder 303 for the second surface layer.

[0068] By the above multilayer extrusion molding, a sheet for forming a container with a thickness of 556.0 μm (hereinafter also referred to as "the sheet of Example 1") was obtained for a target thickness of 550 ± 27.5 μm. The results of physical property measurements for this sheet of Example 1 are shown in Table 1 below. For the sheet of Example 1, with respect to the target thickness of the first surface layer of 50 ± 10.0 μm, the thickness of the first surface layer was 33.0 μm, with respect to the target thickness of the base material layer of 450 ± 20.0 μm, the thickness of the intermediate layer was 488.0 μm, and with respect to the target thickness of the second surface layer of 50 ± 10.0 μm, the thickness of the second surface layer was 35.0 μm. The obtained sheet had an oxygen permeability of 57.4 cm 3 / (m 2 ·24h·atm) at a thickness of 540 μm. The oxygen transmission coefficient of the obtained sheet (laminate) was 30682 cm 3 ·μm / (m 2 ·24h·atm), and the oxygen transmission coefficient of the base material layer was 29081 cm 3 ·μm / (m 2 ·24h·atm), indicating excellent oxygen barrier properties.

[0069] Furthermore, after heating the obtained sheet to 150 to 160°C with a radiation thermometer, it was vacuum formed into a cup-shaped container one by one. The oxygen permeability at a thickness of 130 μm on the side surface of the obtained cup-shaped container was 220.3 cm 3 / (m 2 ·24h·atm). The oxygen transmission coefficient of the container calculated from the obtained sheet was 28645 cm 3·μm / (m 2 ·24 h·atm), and the oxygen permeability coefficient of the base material layer was 27007 cm 3 ·μm / (m 2 ·24 h·atm), and it had excellent oxygen barrier properties. Also, the difference in the oxygen permeability coefficient of the base material layer before and after container formation calculated from the above formula (5) was -2074 cm 3 ·μm / (m 2 ·24 h·atm), and excellent oxygen barrier properties were maintained even after container molding.

[0070]

Table 1

[0071] (Example 2) A container-forming sheet for Example 2 (hereinafter also referred to as "the sheet of Example 2") was obtained in the same manner as in Example 1, except that polypropylene resin (trade name: Novatec (registered trademark) EA9, manufactured by Japan Polypropylene Corporation), 45.5% by mass, polyethylene resin (trade name: HB420RJ, manufactured by Japan Polyethylene Corporation), 19.5% by mass, modified polypropylene (trade name: P613, manufactured by Dow Chemical Japan), 5.0% by mass, and gold mica (trade name: S-400, particle size 20 μm, manufactured by Repco), 30% by mass were supplied to the single-screw extruder 302 for the base material layer via a hopper with respect to 100% by mass of the base material layer.

[0072] In the sheet of Example 2, the thickness of the first surface layer was 40.0 μm, the thickness of the base material layer was 452.0 μm, and the thickness of the second surface layer was 35.0 μm. The obtained sheet had an oxygen permeability of 52.8 cm 3 / (m 2 ·24 h·atm). The oxygen permeability coefficient of the obtained sheet (laminate) was 28514 cm 3 ·μm / (m 2 ·24 h·atm), and the oxygen permeability coefficient of the base material layer was 26583 cm 3 ·μm / (m 2 ·24 h·atm), and it had excellent oxygen barrier properties.

[0073] Furthermore, a cup-shaped container was formed from the sheet of Example 2 using the same method as in Example 1. The oxygen permeability at a side thickness of 200 μm of the resulting cup-shaped container was 109.3 cm². 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the container was 21878 cm³. 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 19992 cm² 3 ·μm / (m 2 The oxygen barrier properties were excellent (24h·atm). Furthermore, the difference in the oxygen permeability coefficient of the substrate layer before and after container formation, calculated from the above formula (5), was -6591 cm⁻¹. 3 ·μm / (m 2 (24h·atm) and excellent oxygen barrier properties were maintained even after container molding.

[0074] (Example 3) The container-forming sheet for Example 3 (hereinafter also referred to as "the sheet for Example 3") was obtained in the same manner as in Example 1, except that polypropylene resin (product name: Novatec® EA9, manufactured by Nippon Polypropylene Co., Ltd.) was supplied to the single-screw extruder 302 for the base layer via a hopper in the following proportions: 48.8% by mass of polypropylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.), 20.9% by mass of polyethylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.), 0.3% by mass of fatty acid ester surfactant (product name: Tirabazole D-818M, manufactured by Taiyo Kagaku Co., Ltd.), and 30.0% by mass of gold mica (product name: S-200HG, particle size 50 μm, manufactured by Repco Co., Ltd.) per 100% by mass of the base layer.

[0075] In the sheet of Example 3, the thickness of the first surface layer was 32.0 μm, the thickness of the substrate layer was 474.0 μm, and the thickness of the second surface layer was 28.0 μm. The obtained sheet had an oxygen permeability of 46.7 cm² at a thickness of 540 μm. 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the obtained sheet (laminated material) was 25229 cm². 3 ·μm / (m 2 The temperature is 24h·atm, and the oxygen permeability coefficient of the substrate layer is 23720 cm². 3·μm / (m 2 It had excellent oxygen barrier properties (24h·atm).

[0076] Furthermore, a cup-shaped container was formed from the sheet of Example 3 using the same method as in Example 1. The oxygen permeability at a side thickness of 130 μm of the resulting cup-shaped container was 281.9 cm². 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the container was 36661 cm³. 3 ·μm / (m 2 The temperature was 24 hours at m. Furthermore, the difference in the oxygen permeability coefficient of the substrate layer before and after container formation, calculated from the above formula (5), was 11698 cm². 3 ·μm / (m 2 It was a 24-hour ATM.

[0077] (Example 4) Except that polypropylene resin (product name: Novatec® EA9, manufactured by Nippon Polypropylene Co., Ltd.) was supplied to the single-screw extruder 302 for the base layer via a hopper in the following proportions: 48.8% by mass of polypropylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.) relative to 100% by mass of the base layer, 20.9% by mass of polyethylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.), 0.3% by mass of fatty acid ester surfactant (product name: Tirabazole D-818M, manufactured by Taiyo Kagaku Co., Ltd.), and 30.0% by mass of white mica (product name: M-200, particle size 50 μm, manufactured by Repco Co., Ltd.), the container forming sheet of Example 4 (hereinafter also referred to as "the sheet of Example 4") was obtained in the same manner as in Example 1.

[0078] In the sheet of Example 4, the thickness of the first surface layer was 32.0 μm, the thickness of the substrate layer was 514.0 μm, and the thickness of the second surface layer was 33.0 μm. The obtained sheet had an oxygen permeability of 53.7 cm² at a thickness of 550 μm. 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the obtained sheet (laminated material) was 29558 cm². 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 28076 cm². 3 ·μm / (m 2It was a 24-hour ATM.

[0079] Furthermore, a cup-shaped container was formed from the sheet of Example 4 using the same method as in Example 1. The oxygen permeability at a side thickness of 210 μm of the resulting cup-shaped container was 231.1 cm². 3 / (m 2 The temperature was 24 hours at 2 hours. The oxygen permeability coefficient of the container was 48552 cm³. 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 48291 cm². 3 ·μm / (m 2 The value was (24h·atm). Furthermore, the difference in the oxygen permeability coefficient of the substrate layer before and after container formation, calculated from the above formula (5), was 20215cm². 3 ·μm / (m 2 It was a 24-hour ATM.

[0080] (Example 5) The container-forming sheet for Example 5 (hereinafter also referred to as "the sheet for Example 5") was obtained in the same manner as in Example 1, except that polypropylene resin (product name: Novatec® EA9, manufactured by Nippon Polypropylene Co., Ltd.) was supplied to the single-screw extruder 302 for the base layer via a hopper in the following proportions: 34.7% by mass of polypropylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.) relative to 100% by mass of the base layer, 14.9% by mass of polyethylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.), 0.5% by mass of fatty acid ester surfactant (product name: Tirabazole D-818M, manufactured by Taiyo Kagaku Co., Ltd.), and 50.0% by mass of gold mica (product name: S-200HG, particle size 50 μm, manufactured by Repco Co., Ltd.) relative to 100% by mass of the base layer via a hopper.

[0081] In the sheet of Example 5, the thickness of the first surface layer was 24.0 μm, the thickness of the substrate layer was 488.0 μm, and the thickness of the second surface layer was 14.0 μm. The obtained sheet had an oxygen permeability of 29.1 cm² at a thickness of 535 μm. 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the obtained sheet (laminated material) was 15571 cm². 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 14774 cm²3 ·μm / (m 2 It had excellent oxygen barrier properties (24h·atm).

[0082] Furthermore, a cup-shaped container was formed from the sheet of Example 5 using the same method as in Example 1. The oxygen permeability at a side thickness of 170 μm of the resulting cup-shaped container was 272.8 cm². 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the container was 46384 cm³. 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 46078 cm². 3 ·μm / (m 2 The temperature was 24 hours at m. Furthermore, the difference in the oxygen permeability coefficient of the substrate layer before and after container formation, calculated from the above formula (5), was 31304 cm². 3 ·μm / (m 2 It was a 24-hour ATM.

[0083] (Comparative Example 1) A container-forming sheet for Comparative Example 1 (hereinafter also referred to as "the sheet for Comparative Example 1") was obtained in the same manner as in Example 1, except that polypropylene resin (product name: Novatec® EA9, manufactured by Nippon Polypropylene Co., Ltd.) was supplied to a single-screw extruder 302 for the base layer via a hopper in an amount of 70.0% by mass relative to 100% by mass of the base layer, and polyethylene resin (product name: HB420RJ, manufactured by Nippon Polyethylene Co., Ltd.) was supplied in an amount of 30.0% by mass, and mica and dispersant were not supplied.

[0084] In the sheet of Comparative Example 1, the thickness of the first surface layer was 37.0 μm, the thickness of the substrate layer was 460.0 μm, and the thickness of the second surface layer was 35.0 μm. The obtained sheet had an oxygen permeability of 101.7 cm² at a thickness of 550 μm. 3 / (m 2 The temperature was 24 hours at 24 hours. The oxygen permeability coefficient of the obtained sheet (laminated material) was 55949 cm². 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 56867 cm². 3 ·μm / (m 2The temperature was 24 hours at 24 hours. The substrate layer of the sheet in Comparative Example 1 did not contain mica or a dispersant, and therefore insufficient oxygen barrier properties were not obtained.

[0085] Furthermore, a cup-shaped container was formed from the sheet of Comparative Example 1 using the same method as in Example 1. The oxygen permeability at a side thickness of 150 μm of the resulting cup-shaped container was 395.6 cm². 3 / (m 2 The temperature was (24h·atm). The oxygen permeability coefficient of the container was 59393 cm³. 3 ·μm / (m 2 (24h·atm) The oxygen permeability coefficient of the substrate layer is 61026cm² 3 ·μm / (m 2 The oxygen barrier properties were (24h·atm), and sufficient oxygen barrier performance was not obtained even after container molding. Furthermore, the difference in the oxygen permeability coefficient of the substrate layer before and after container formation, calculated from the above formula (5), was 4159 cm⁻¹. 3 ·μm / (m 2 It was a 24-hour ATM.

[0086] The container-forming sheets in Examples 1 to 5 all have an oxygen permeability coefficient of 32,000 cm² in the base layer. 3 ·μm / (m 2 • Below 24h·atm, the oxygen permeability coefficient of the sheet (laminated material) is 33,000 cm². 3 ·μm / (m 2 The oxygen barrier properties were excellent, with a coefficient of oxygen permeability of 50,000 cm² in the substrate layer of the containers obtained from the container-forming sheets of Examples 1 to 5. 3 ·μm / (m 2 The oxygen permeability coefficient was less than 24h·atm, indicating sufficient oxygen barrier properties. In particular, for Examples 1 and 2, the difference in the oxygen permeability coefficient of the base layer before and after container formation was negative, indicating that excellent oxygen barrier properties were maintained even after the molding process. Furthermore, from the results of Examples 1 and 2 and Example 4, it was found that using gold mica is more preferable among mica types. On the other hand, Comparative Example 1 did not contain mica or a dispersant in the base layer, and its oxygen permeability coefficient was outside the above numerical range, so sufficient oxygen barrier properties could not be obtained. [Explanation of symbols]

[0087] 100-layer structure 101 Base material layer 102 (First) surface layer 103 (Second) Surface Layer 300 Multilayer Co-Extrusion Molding Machine 301 Extruder for the first surface layer 302 Extruder for base material layers 303 Extruder for the second surface layer 304 Feedblock 305 dice 306 Three-layer laminated structure

Claims

1. A laminate comprising a base layer and surface layers provided on both sides of the base layer, The substrate layer comprises a polyolefin resin, mica, and a dispersant. The oxygen permeability coefficient of the aforementioned substrate layer is 32,000 cm². ３ • μm / (m) ２ A laminate that is below 24 hours (atm).

2. The oxygen permeability coefficient of the aforementioned laminate is 33,000 cm². ３ • μm / (m) ２ The laminate according to claim 1, wherein the humidity is 24 h·atm or less.

3. The laminate according to claim 1 or 2, wherein the mica is gold mica.

4. The laminate according to claim 1 or 2, wherein the particle size of the mica is 20 μm to 50 μm.

5. The laminate according to claim 1 or 2, wherein the content of the mica is 30% by mass to 50% by mass relative to the total amount of the base material layer.

6. The laminate according to claim 1 or 2, wherein the dispersant comprises either or both a fatty acid ester surfactant and modified polypropylene.

7. The laminate according to claim 1 or 2, wherein the polyolefin resin comprises a polypropylene resin and a polyethylene resin.

8. A sheet for forming a container, comprising the laminate described in claim 1 or 2.

9. The container-forming sheet according to claim 8, wherein the oxygen permeability coefficient of the base material layer in a container formed from the container-forming sheet is lower than the oxygen permeability coefficient of the base material layer in the container-forming sheet.

10. A container formed using the container-forming sheet described in claim 8.

11. The oxygen permeability coefficient of the substrate layer in the aforementioned container is 29,000 cm². ３ • μm / (m) ２ The container according to claim 10, wherein the humidity is 24 h·atm or less.

12. The oxygen permeability coefficient of the aforementioned container is 31,000 cm². ３ • μm / (m) ２ The container according to claim 10, wherein the humidity is 24 h·atm or less.

13. The container according to claim 11, wherein the oxygen permeability coefficient of the base layer in the container formed from the container forming sheet is lower than the oxygen permeability coefficient of the base layer in the container forming sheet.

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