Chemical resistant laminates

Abstract

The present invention provides a novel chemical resistant laminate capable of suppressing delamination even when exposed to a chemical substance such as alcohol for a long period of time.SOLUTION: As shown in FIG. 1, the chemical resistant laminate 100 of the present invention comprises a barrier base layer 102, an anchor coat layer 108, a polyethylene layer 104, and a sealant layer 106, wherein the barrier base layer 102 comprises a metallic layer 1022, the anchor coat layer 108 comprises a maleic anhydride-containing modified polyolefin and is directly laminated on the metallic layer 1022, and the polyethylene resin constituting the polyethylene layer 104 has a modulus of elasticity of 110MPa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a chemically resistant laminate. [Background technology]

[0002] Conventionally, laminates used for packaging bags for hermetically packaging chemical substances such as alcohol-containing substances have been, for example, laminates in which a base layer, a barrier layer, a sealant layer, etc. are laminated and bonded to each other with an adhesive layer.

[0003] However, when the contents to be packaged are high-concentration alcohol, for example, 50% by mass or more, the alcohol component permeates the laminate during long-term storage, and particularly attacks the adhesive layer between the barrier layer and the sealant layer, resulting in the sealant layer peeling off from the barrier layer (delamination), causing damage to the packaging bag. Various proposals have been made to address this problem.

[0004] Patent Document 1 discloses an alcohol-resistant laminate having, in this order, a substrate resin layer, a substrate adhesive layer, a metal foil layer, a first adhesive layer, a barrier layer other than the metal foil layer, a second adhesive layer, and a sealant layer.

[0005] Patent Document 2 discloses a highly resistant packaging laminate characterized in that a substrate layer, a metal layer, an adhesive layer, and a thermoplastic resin layer are laminated in this order from the surface layer side, the metal layer having a surface modification layer at least on the surface facing the adhesive layer, the adhesive layer containing at least acid-modified polyethylene and low-density polyethylene, and being a melt-coextruded layer in which the acid-modified polyethylene layer is disposed on the metal layer side and the low-density polyethylene layer is disposed on the thermoplastic resin layer side, and the substrate layer, metal layer, and thermoplastic resin layer are sandwich-laminated.

[0006] Patent Document 3 discloses a packaging material for alcohol-containing liquids, which has at least a polyester-based resin film layer, an anchor coat layer laminated adjacent to the polyester-based resin film layer, and a polyolefin-based resin layer laminated adjacent to the anchor coat layer, wherein the anchor coat layer is formed by applying an aqueous dispersion containing a polyolefin copolymer resin containing 0.01 to 5 mass % of an unsaturated carboxylic acid or an anhydride thereof and a crosslinking agent, but not containing a non-volatile water-imparting aid, and dispersing the polyolefin copolymer resin in an aqueous solvent so that the number average particle diameter is 1 μm or less, onto the polyester-based resin film layer and drying the aqueous dispersion. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2020-192769 [Patent Document 2] Japanese Patent Publication No. 2022-122641 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-124565 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a novel chemically resistant laminate that can suppress peeling even when exposed to highly reactive chemicals such as alcohol for a long period of time. [Means for solving the problem]

[0009] The present inventors have conducted extensive research and found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows: <Aspect 1> A film having a barrier substrate layer, an anchor coat layer, a polyethylene layer, and a sealant layer, the barrier substrate layer has a metal foil layer, the anchor coat layer is made of a modified polyolefin containing a maleic anhydride component and is directly laminated on the metal foil layer; The polyethylene resin constituting the polyethylene layer is formed into a film having a thickness of 200 μm, which is then punched into a dumbbell No. 3 shape conforming to JIS K 6251, and when a tensile test is carried out using this at a support distance of 20 mm, the elastic modulus of the polyethylene resin is 110 MPa or less. Chemical resistant laminate. <Aspect 2> The chemical-resistant laminate according to aspect 1, wherein the sealant layer is made of a polyethylene-based resin. <Aspect 3> A bag made of the chemical-resistant laminate described in Aspect 1 or 2. <Aspect 4> The bag according to aspect 3, and The contents enclosed in the bag A bag containing contents. <Aspect 5> A bag containing contents as described in Aspect 4, wherein the contents are at least one selected from the group consisting of alcohol-containing contents and contents containing acids, alkalis, salts, solvents, oils, and other chemical substances as ingredients. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a novel chemically resistant laminate that can suppress peeling even when exposed to highly reactive chemicals such as alcohol for a long period of time. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional side view of a chemically resistant laminate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] 《Chemical resistant laminate》 The chemically resistant laminate of the present invention comprises: The film has a barrier substrate layer, an anchor coat layer, a polyethylene layer, and a sealant layer, the barrier substrate layer has a metal foil layer, the anchor coat layer is made of a modified polyolefin containing a maleic anhydride component and is directly laminated on the metal foil layer; The polyethylene resin constituting the polyethylene layer is formed into a film having a thickness of 200 μm, which is then punched into a No. 3 dumbbell shape conforming to JIS K 6251. When a tensile test is conducted using this at a support distance of 20 mm, the elastic modulus of the polyethylene resin is 110 MPa or less.

[0013] The present inventors have found that the above-mentioned configuration can suppress peeling even when exposed to highly reactive chemicals such as alcohol for a long period of time. Without wishing to be bound by theory, this is thought to be due to the interaction between the fact that an anchor coat layer made of a specific modified polyolefin is laminated to a metal foil layer and a specific polyethylene layer is laminated to this anchor coat layer, particularly by welding, so that the respective bonding surfaces have high resistance to such chemicals, and the fact that the polyethylene resin making up this polyethylene layer is relatively flexible, thereby alleviating internal stress.

[0014] In this specification, "chemical resistance" means the ability of a material to withstand exposure to acids, alkalis, salts, solvents, oils, and other chemicals, and is sometimes referred to as "chemical resistance" by those skilled in the art.

[0015] As shown in FIG. 1, the chemically resistant laminate 100 of the present invention includes: The film has a barrier substrate layer 102, an anchor coat layer 108, a polyethylene layer 104, and a sealant layer 106, the barrier substrate layer 102 has a metal foil layer 1022; the anchor coat layer 108 is made of a modified polyolefin containing a maleic anhydride component and is directly laminated on the metal foil layer 1022; The polyethylene resin constituting the polyethylene layer 104 is formed into a film having a thickness of 200 μm, which is then punched out into a dumbbell shape No. 3 conforming to JIS K 6251. When a tensile test is performed using this with a support distance of 20 mm, the elastic modulus of the polyethylene resin is 110 MPa or less.

[0016] Each component of the present invention will be described below.

[0017] <Barrier substrate layer> The barrier substrate layer is a layer located outside the anchor coat layer. The barrier substrate layer has a metal foil layer. The anchor coat layer is laminated on the metal foil layer.

[0018] The barrier substrate layer may be composed of at least one of a resin substrate layer and a paper substrate layer, and a metal foil layer, and these layers may be laminated together via an adhesive layer.

[0019] The resin substrate layer, the paper substrate layer and the barrier layer may each be present in one or more layers.

[0020] A printed layer may be laminated on at least a part of the above-mentioned layers constituting the base layer, and this printed layer may be printed by gravure printing, flexographic printing, or the like.

[0021] The thickness of the substrate layer is not particularly limited and may be, for example, 7 μm or more and 100 μm or less. This thickness may be 7 μm or more or 10 μm or more, or may be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0022] (Resin base layer) The resin substrate layer may be composed of a thermoplastic resin having excellent impact resistance, abrasion resistance, etc., such as a vinyl resin, a polyester resin, a polyamide resin, etc. The resin substrate layer may be a single layer or a laminate.

[0023] Examples of vinyl resins include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polychlorotrifluoroethylene, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene, and polyacrylonitrile (PAN).

[0024] Examples of polyester resins include polyethylene terephthalate (PET) and polybutylene terephthalate.

[0025] Examples of polyamide resins include nylons such as Nylon (registered trademark) 6 and Nylon MXD6.

[0026] From the viewpoint of the mechanical strength of the chemical-resistant laminate, the thickness of one resin substrate layer is preferably 7 μm or more, or 10 μm or more, and may be 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 17 μm or less, or 15 μm or less.

[0027] The resin constituting the resin substrate layer may be one type or a blend of two or more types, and additives for imparting functionality, etc. may be blended as necessary.

[0028] The resin substrate layer is preferably produced from a preformed film. The film to be the resin substrate layer may be any film formed from the above-mentioned resins, and may be unstretched or uniaxially or biaxially stretched. Of these, a biaxially stretched film is preferred.

[0029] (Paper base layer) The paper substrate layer may be coated paper, art paper, or the like.

[0030] The basis weight of the paper that makes up the paper base layer is 10 g / m 2 More than 30g / m 2 or more, or 50 g / m 2 or more, and may be 200 g / m 2 Below 150g / m 2 or less than 100g / m 2 It may be the following:

[0031] (metal foil layer) The metal foil layer is a layer on which the anchor coat layer is directly laminated.

[0032] As the metal foil layer, for example, a simple metal foil layer such as copper foil or aluminum foil, or an alloy foil layer such as stainless steel foil can be used.

[0033] The thickness of the metal foil layer is preferably 5 μm or more, or 7 μm or more, from the viewpoint of ensuring strength and barrier properties, and is preferably 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less, from the viewpoint of reducing the thickness of the entire chemical-resistant laminate.

[0034] (Other barrier layers) The other barrier layer can be made of a material capable of suppressing the permeation of moisture, organic gases, inorganic gases, etc. between the barrier substrate layer and the sealant layer and / or protecting substances located on the sealant layer side. Examples of such barrier layers include inorganic vapor-deposited films such as silica vapor-deposited films, alumina vapor-deposited films, aluminum vapor-deposited films, and silica-alumina binary vapor-deposited films; barrier resin layers such as ethylene-vinyl alcohol copolymer (EVOH), cyclic olefin polymer (COP), and cyclic olefin copolymer (COC); and organic coating films such as polyvinylidene chloride coating films, polychlorotrifluoroethylene coating films, and polyvinylidene fluoride coating films.

[0035] In particular, among the above other barrier layers, the inorganic vapor deposition film, the barrier resin layer, and the organic coating film can function as a transparent barrier layer.

[0036] When an inorganic vapor deposition film or an organic coating film is used as the other barrier layer, the thickness of the barrier layer is preferably 100 nm or more, 200 nm or more, 300 nm or more, 500 nm or more, 700 nm or more, or 1 μm or more from the viewpoint of ensuring strength and barrier properties, and is preferably 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less from the viewpoint of reducing the thickness of the entire chemical-resistant laminate.

[0037] When a metal foil layer or a barrier resin layer is used as the other barrier layer, the thickness of the barrier layer is preferably 5 μm or more, or 7 μm or more, from the viewpoint of ensuring strength and barrier properties, and is preferably 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less, from the viewpoint of reducing the thickness of the entire chemical-resistant laminate.

[0038] <Anchor coat layer> The anchor coat layer is a layer made of a modified polyolefin containing a maleic anhydride component, and is laminated directly on the metal foil layer of the barrier substrate layer.

[0039] An anchor coat layer can be applied to the surface of an object to be bonded to modify the surface, thereby promoting adhesion. In particular, when an anchor coat layer having polar groups is laminated on a resin layer such as a resin substrate layer, the anchor coat layer generally promotes oxidation of the surface of the resin layer, thereby promoting polar adhesion between the surface and the anchor coat layer. This allows for good adhesion when a polyethylene layer is applied by sand lamination at high temperatures, for example, at temperatures of 300°C or higher, 310°C or higher, 320°C or higher, or 330°C or higher.

[0040] In particular, in the present invention, the anchor coat layer may be laminated on the metal foil layer in advance before sand lamination in the manufacturing stage. In this case, the sand lamination may be performed in the above-mentioned high-temperature environment.

[0041] <Polyethylene layer> The polyethylene layer is present between the barrier substrate layer and the sealant layer. In particular, the polyethylene layer may be a layer formed by sand lamination.

[0042] The polyethylene layer is made of a polyethylene-based resin.

[0043] In this specification, a polyethylene-based resin is a resin that contains more than 50 mol%, 60 mol% or more, 70 mol% or more, or 80 mol% or more of ethylene group repeating units in the main chain of the polymer, and is selected from the group consisting of, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), polyethylene plastomer, derivatives thereof, and mixtures thereof.

[0044] The density of polyethylene resin is 0.900 g / cm 3 More than 0.905g / cm 3 More than 0.910g / cm 3 or more, or 0.915 g / cm 3 or more, and may be 0.950 g / cm 3 Below, 0.945g / cm 3 Below, 0.940g / cm 3 Below, 0.935g / cm 3 Below, 0.925g / cm 3 or less, or 0.920 g / cm 3 In particular, the density may be 0.930 g / cm or less. 3 From the viewpoint of heat seal strength, it is preferable that the above-mentioned value is as follows.

[0045] The polyethylene resin constituting the polyethylene layer is a polyethylene resin having an elastic modulus of 110 MPa or less when the polyethylene resin constituting the polyethylene layer is formed into a film having a thickness of 200 μm, which is then punched into a No. 3 dumbbell shape in accordance with JIS K 6251, and a tensile test is performed using this film at a support distance of 20 mm. The elastic modulus may be 10 MPa or more and 110 MPa or less, for example, 10 MPa or more, 15 MPa or more, 20 MPa or more, 25 MPa or more, 30 MPa or more, 35 MPa or more, 40 MPa or more, 45 MPa or more, 50 MPa or more, 55 MPa or more, 60 MPa or more, 65 MPa or more, 70 MPa or more, 75 MPa or more, 80 MPa or more, or 85 MPa or more, or may be 105 MPa or less.

[0046] The thickness of the polyethylene layer may be 5 μm or more and 50 μm or less, or may be 5 μm or more, 10 μm or more, 15 μm or more, or 18 μm or more, or may be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, or 22 μm or less.

[0047] <Sealant layer> The sealant layer is a layer that is laminated directly to the polyethylene layer.

[0048] It is preferred that at least the surface of the sealant layer that is in contact with the polyethylene layer is not subjected to a corona treatment, and in particular, both surfaces of the sealant layer do not need to be corona treated.

[0049] The sealant layer may be made of, for example, a polyethylene-based resin. The sealant layer can be provided in the form of, for example, a stretched or non-stretched film, a molten resin for extrusion lamination, a hot-melt coating, etc. Among these, it is preferable that the sealant layer be a stretched or non-stretched film, i.e., that the sealant layer be a sealant film layer, from the viewpoint of ease of production.

[0050] The thickness of the sealant layer is preferably 10 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, or 70 μm or more from the viewpoint of ensuring strength, and is preferably 200 μm or less, 180 μm or less, 150 μm or less, 130 μm or less, 100 μm or less, or 90 μm or less from the viewpoint of manufacturing.

[0051] "bag" The bag of the present invention is constructed from the above-described chemically resistant laminate, wherein the sealant layer of the chemically resistant laminate may be disposed on the side that will come into contact with the contents.

[0052] In the bag of the present invention, the chemically resistant laminate of the present invention may be heat-sealed, for example, with the sealant layers facing each other. When the bag is made up of two chemically resistant laminates, the two chemically resistant laminates may be made of the same material or different materials.

[0053] 《Bag containing contents》 The content-containing bag of the present invention comprises the above-mentioned bag, and The contents contained in this bag It has.

[0054] The contents may be at least one selected from the group consisting of alcohol-containing contents and contents containing acids, alkalis, salts, solvents, oils, and other chemical substances as ingredients, such as hair color, soap, acid detergent, insecticide, pesticide, etc.

[0055] In particular, the contents may be alcohol-containing contents. The alcohol-containing contents may contain, for example, 10 vol% or more, 15 vol% or more, 20 vol% or more, 25 vol% or more, 30 vol% or more, 35 vol% or more, 0 vol% or more, 45 vol% or more, 50 vol% or more, 55 vol% or more, 60 vol% or more, 65 vol% or more, 70 vol% or more, 75 vol% or more, 80 vol% or more, 85 vol% or more, 90 vol% or more, 95 vol% or more, or 100 vol% alcohol. The content-filled bag of the present invention is particularly useful in that it can suppress peeling that can occur when the alcohol content is 50 vol% or more.

[0056] Examples of such high-concentration alcohol-containing contents include alcohol-containing disinfectants, alcohol-impregnated sheets, alcoholic beverages, and alcohol-containing foods.

[0057] In addition to alcohol, the chemical substances contained in the contents include acids such as carboxylic acids and inorganic acids, alkalis such as amines, salts such as alkali metal salts of fatty acids, solvents, oils, pyrethroids (insecticide components), and other chemical substances. [Example]

[0058] The present invention will be specifically explained with reference to examples and comparative examples, but the present invention is not limited to these.

[0059] Example 1 Using a dry laminator, a two-component urethane dry laminating adhesive was applied at 3.0 to 4.0 g / m to a nylon film (Ny: 15 μm) as a resin substrate layer. 2 The laminate was coated with a dry lamination adhesive and then laminated with an aluminum foil (Al: 7 μm) as a barrier layer. The adhesive was then cured by storing and aging the laminate for 72 hours at 40°C to obtain a laminate consisting of Ny / / Al as a barrier substrate layer (" / / " indicates that the layer was bonded with a dry lamination adhesive).

[0060] The Al surface of the barrier substrate layer was subjected to a 2.0 kW corona treatment, and then a modified polyolefin anchor coating agent containing maleic anhydride was applied at 0.3 g / m 2 A linear low-density polyethylene (LLDPE) film (thickness 80 μm) that had not been subjected to corona treatment was laminated on top of the coated film via a linear low-density polyethylene (LLDPE1) polyethylene having the physical properties shown in Table 1, which had been melted at 320°C to 340°C, to produce the chemical-resistant laminate of Example 1. The melted polyethylene was set to have a thickness of 20 μm.

[0061] Example 2 and Comparative Examples 1 to 3 Chemical-resistant laminates of Example 2 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that the type of polyethylene-based resin constituting the polyethylene layer was changed to one shown in Table 1. The materials constituting the "polyethylene layer" in Table 1 are as follows: LDPE: Low-density polyethylene HDPE: High density polyethylene EMAA: Ethylene-methacrylic acid copolymer

[0062] <<Evaluation of laminate strength>> The chemically resistant laminate was cut into a size of 80 mm in the molding direction (MD) × 320 mm in the transverse direction (TD), folded along the long side with the sealant layers facing each other, and heat-sealed at one point on each of the long and short sides at a width of 10 mm using an impulse sealer (FA-300-10W, Fuji Impulse Co., Ltd.) at 200°C for 1 second to create a bag shape.

[0063] The bag produced as described above was allowed to stand at room temperature for 24 hours after production, and then cut out to a width of 15 mm so as to include the heat-sealed portion. The seal strength (heat seal strength) of the 15 mm width between the barrier substrate layer and the polyethylene layer in the heat-sealed portion was measured using a T-peel test in accordance with JIS Z 0238, and this was taken as the initial strength of the laminate.

[0064] Next, this bag was filled with 20 g of an 80 vol% aqueous ethanol solution, and the remaining side was heat-sealed under the same conditions as above to form a three-sided sealed bag. The aqueous solution was then sealed to produce a three-sided sealed bag containing ethanol.

[0065] The heat seal strength of the three-sided sealed bags was also measured in the same way after they had been stored for two weeks (2W). For the accelerated test, the bags were stored at 50°C, and then returned to room temperature and left to stand for three hours.

[0066] The same measurement was carried out five times both initially and after storage, and the average value was calculated.These values ​​were used to calculate the rate of decrease in laminate strength.

[0067] Table 1 shows the configurations and evaluation results of the examples and comparative examples.

[0068] [Table 1]

[0069] From Table 1, it can be seen that the chemical-resistant laminate of the example, in which the anchor coat layer is composed of a modified polyolefin containing a maleic anhydride component and is laminated directly to the metal foil layer, and the polyethylene resin has an elastic modulus of 110 MPa or less, can suppress peeling even when exposed to alcohol for a long period of time. [Explanation of symbols]

[0070] 100 Chemical resistant laminate 102 Barrier substrate layer 1022 Metal foil layer 104 polyethylene layer 106 Sealant Layer 108 Anchor coat layer

Claims

1. The film has a barrier substrate layer, an anchor coat layer, a polyethylene layer, and a sealant layer, the barrier substrate layer has a metal foil layer, the anchor coat layer is made of a modified polyolefin containing a maleic anhydride component and is directly laminated on the metal foil layer; the polyethylene-based resin constituting the polyethylene layer is formed into a film having a thickness of 200 μm, which is then punched into a dumbbell-shaped No. 3 shape in accordance with JIS K 6251, and a tensile test is carried out using this film at a support distance of 20 mm. When this test is carried out, the elastic modulus of the polyethylene-based resin is 110 MPa or less; Chemical resistant laminate.

2. 2. The chemically resistant laminate according to claim 1, wherein the sealant layer is made of a polyethylene resin.

3. A bag made of the chemically resistant laminate of claim 1 or 2.

4. The bag according to claim 3, and The contents enclosed in the bag A bag containing contents.

5. 5. The bag according to claim 4, wherein the contents are at least one selected from the group consisting of alcohol-containing contents and contents containing acids, alkalis, salts, solvents, oils, and other chemical substances as components.

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