tape

Abstract

To provide a tape with an EVOH-containing layer that achieves both gas barrier properties and flexibility.SOLUTION: A tape has an ethylene-vinyl alcohol-based copolymer layer containing an ethylene-vinyl alcohol-based copolymer with an ethylene content of 20 mol% or more and less than 32 mol%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a tape, and more specifically to a tape having excellent gas barrier properties and flexibility. [Background technology]

[0002] 2. Description of the Related Art Adhesive tapes produced by applying an adhesive to a base film made of a thermoplastic resin are in wide use. Moreover, ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH"), which is one type of thermoplastic resin, has very strong intermolecular forces due to hydrogen bonds between hydroxyl groups present in the polymer side chains. Therefore, it has high crystallinity and the intermolecular forces are also strong in the amorphous part, so that a film using EVOH is difficult for gas molecules to pass through and shows excellent gas barrier properties. EVOH with such properties is used as a gas barrier layer to impart gas barrier properties to a base film.

[0003] For example, Patent Document 1 discloses a laminate (tape) having an EVOH layer with an ethylene content of 35 to 49 mol % and a layer thickness of 2 to 9 microns. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-45526 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the tape disclosed in Patent Document 1, it is necessary to increase the thickness of the EVOH layer in order to achieve higher gas barrier properties. However, when the thickness of the EVOH layer is increased, the flexibility of the tape becomes insufficient, and there is room for further improvement.

[0006] The present invention has been made in view of the above problems, and has an object to provide a tape having an EVOH-containing layer that combines gas barrier properties and flexibility. [Means for solving the problem]

[0007] However, in light of these circumstances, the inventors conducted extensive research and discovered that by using EVOH with a lower ethylene content than conventional EVOH, a tape having both gas barrier properties and flexibility can be obtained, thus completing the present invention.

[0008] That is, the present invention has the following aspects. [1] A tape having an EVOH layer containing EVOH with an ethylene content of 20 mol% or more and less than 32 mol%. [2] The tape according to [1], wherein the EVOH layer has a thickness of 0.1 to 80 μm. [3] The tape according to [1] or [2], wherein the ethylene content of the EVOH is 20 mol% or more and 30 mol% or less. [4] The tape according to any one of [1] to [3], wherein the EVOH has a melt flow rate (210°C, load 2160 g) of 2 to 15 g / 10 min. [5] The tape according to any one of [1] to [4], wherein the EVOH content in the EVOH layer is 50 mass % or more. [6] The tape according to any one of [1] to [5], having a thickness of 10 to 400 μm. [7] The tape according to any one of [1] to [6], wherein the ratio of the thickness of the EVOH layer to the thickness of the tape (EVOH layer / tape) is 1 / 100 to 1 / 2. [8] The tape according to any one of [1] to [7], which is for protecting a container having gas barrier properties. [9] The tape according to any one of [1] to [7], which is for edge protection. Effect of the Invention

[0009] According to the present invention, by having an EVOH layer containing EVOH having an ethylene content of 20 mol % or more and less than 32 mol %, it is possible to obtain a tape that combines gas barrier properties, particularly oxygen barrier properties, with flexibility and improved handleability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below based on examples of the mode for carrying out the present invention. However, the present invention is not limited to the embodiment described below. In the present invention, the term "tape" includes "film" and "sheet".

[0011] In the present invention, when expressed as "X to Y" (X and Y are any numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", as well as "preferably larger than X" or "preferably smaller than Y". Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the meaning that "it is preferably greater than X" or "it is preferably less than Y". Furthermore, "X and / or Y (X and Y are optional)" means at least one of X and Y, and means the following three cases: X only, Y only, and X and Y.

[0012] Hereinafter, the monomer units contained in EVOH and thermoplastic resins may be simply referred to as “units.” For example, a monomer unit based on ethylene may be referred to as an “ethylene unit.”

[0013] A tape according to one embodiment of the present invention (hereinafter, may be referred to as "the present tape") is a tape having an EVOH layer containing EVOH having an ethylene content of 20 mol % or more and less than 32 mol %. The present tape need only have an EVOH layer, and may be, for example, a single-layer tape having only an EVOH layer, a multilayer tape having multiple EVOH layers laminated together, or a multilayer tape having an EVOH layer and a layer containing a thermoplastic resin other than the EVOH layer laminated together. Each component of the tape will now be described.

[0014] [EVOH layer] The thickness of the EVOH layer in the present tape is preferably 0.1 to 80 μm, more preferably 0.5 to 70 μm, even more preferably 1 to 50 μm, particularly preferably 1.5 to 40 μm, and especially preferably 2 to 30 μm. When the thickness of the EVOH layer is within the above range, flexibility tends to be excellent. When the present tape contains multiple EVOH layers, the thickness of the EVOH layer refers to the combined thickness of all the EVOH layers.

[0015] The EVOH layer is formed from an EVOH composition containing EVOH. The EVOH can be obtained by saponifying an ethylene-vinyl ester copolymer. A representative vinyl ester is vinyl acetate, but other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can also be used. The ethylene-vinyl ester copolymer can be produced by any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., and the saponification of the ethylene-vinyl ester copolymer can also be carried out by a known method.

[0016] The ethylene content of the EVOH is 20 mol% or more and less than 32 mol%, preferably 20 mol% or more and 30 mol% or less, more preferably 22 mol% or more and 29 mol% or less, and particularly preferably 24 mol% or more and 26 mol% or less, as measured based on ISO 14663. When the ethylene content of the EVOH is within the above range, the present tape has excellent gas barrier properties and flexibility.

[0017] The melt flow rate (MFR) of the EVOH (210°C, load 2160 g) is preferably 0.1 to 50 g / 10 min, more preferably 1 to 30 g / 10 min, and further preferably 2 to 15 g / 10 min. If the MFR of the EVOH is too high, the film formability tends to be unstable, and if it is too low, the viscosity tends to be too high, making melt extrusion difficult.

[0018] The density of the EVOH is usually 1.1 to 1.4 g / cm, as measured based on JIS K7112:1999B. 3 and preferably 1.15 to 1.3 g / cm 3 , more preferably 1.2 to 1.25 g / cm 3 When the density of EVOH is within the above range, the gas barrier property tends to be more excellent.

[0019] The degree of saponification of the vinyl ester unit of the EVOH is a value measured based on JIS K6726 (wherein EVOH is a solution uniformly dissolved in a water / methanol solvent), and from the viewpoints of gas barrier property, thermal stability, and moisture resistance, it is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 98 mol% or more, particularly preferably 99 mol% or more, and may be 100 mol%.

[0020] The EVOH may be copolymerized with polymerizable monomers other than ethylene and vinyl esters within a range that does not impair the effects of the present invention, generally within a range of 5 mol% or less. Examples of such polymerizable monomers include α-olefins such as propylene, isobutene, α-octene, α-dodecene, and α-octadecene; hydroxyl-containing α-olefins such as 3-butene-1-ol, 4-pentene-1-ol, and 3-butene-1,2-diol, and hydroxyl-containing α-olefin derivatives such as esters and acylates thereof; hydroxymethylvinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyronyloxy-2-methylenepropane; unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, nitriles, amides, or anhydrides; unsaturated sulfonic acids or salts thereof; vinylsilane compounds; vinyl chloride; and styrene. These can be used alone or in combination of two or more.

[0021] Furthermore, as the EVOH, EVOH that has been "post-modified" such as urethanized, acetalized, cyanoethylated, or oxyalkylened can also be used.

[0022] The content of EVOH contained in the EVOH layer is not particularly limited, but EVOH is preferably the main component (i.e., the content of EVOH contained in the EVOH layer is 50% by mass or more). The content of EVOH is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, 90% by mass or more, and particularly preferably 100% by mass.

[0023] The EVOH layer may contain components other than EVOH, such as antiblocking agents, processing aids, resins other than EVOH, carboxylic acid compounds, phosphoric acid compounds, boron compounds, metal salts, stabilizers, antioxidants, UV absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, surfactants, drying agents, crosslinking agents, reinforcing agents such as various fibers, etc., within a range that does not impair the effects of the present invention, generally within a range of 20 mass % or less. These may be used alone or in combination of two or more kinds.

[0024] [Thermoplastic resin layer] The tape may have a thermoplastic resin layer containing a thermoplastic resin other than the EVOH layer. In the tape, the thermoplastic resin layer may be one layer or may have multiple layers. By having the thermoplastic resin layer, the tape tends to be able to further increase the mechanical strength and gas barrier properties against water vapor. In addition, properties such as mechanical strength can be imparted depending on the type of thermoplastic resin constituting the thermoplastic resin layer.

[0025] The thermoplastic resin is one other than the EVOH, and examples thereof include polyethylenes such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, and high-density polyethylene, ethylene-vinyl acetate copolymers, ionomers, ethylene-propylene (block or random) copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, polypropylene, propylene-α-olefin copolymers, polybutene, and polypentene, and other olefin homopolymers or copolymers thereof, or polyolefins graft-modified with unsaturated carboxylic acids or their esters; polyesters; polyamides (including copolymerized polyamides); polyvinyl chloride; polyvinylidene chloride; acrylic resins; polystyrene; polyvinyl esters; polyester elastomers; polyurethane elastomers; chlorinated polystyrene; chlorinated polypropylene; aromatic polyketones or aliphatic polyketones, and polyalcohols obtained by reducing these; polyacetals; and polycarbonates. These may be used alone or in combination of two or more.

[0026] The content of the thermoplastic resin in the thermoplastic resin layer is not particularly limited, but it is preferable that the thermoplastic resin is the main component (i.e., the content of the thermoplastic resin contained in the thermoplastic resin layer is 50% by mass or more). The content of the thermoplastic resin is more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, 90% by mass or more, 95% by mass or more, and particularly preferably 100% by mass.

[0027] The thermoplastic resin layer may contain components other than the thermoplastic resin, such as antiblocking agents, processing aids, resins other than thermoplastic resins, carboxylic acid compounds, phosphoric acid compounds, boron compounds, metal salts, stabilizers, antioxidants, UV absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, surfactants, drying agents, crosslinking agents, reinforcing agents such as various fibers, etc., within a range that does not impair the effects of the present invention, generally within a range of 20 mass % or less. These may be used alone or in combination of two or more kinds.

[0028] [Layer containing adhesive resin composition] When the thermoplastic resin layer contains polyolefin, the tape may have a layer containing an adhesive resin (hereinafter referred to as an "adhesive resin layer") from the viewpoint of adhesion to the EVOH layer. By having the adhesive resin layer, the appearance characteristics (film surface) of the tape tend to be better.

[0029] The adhesive resin is not particularly limited, but is preferably a polyolefin having a carboxy group, a carboxylic anhydride group, or an epoxy group, and more preferably a polyolefin having a carboxylic anhydride group. Such adhesive resins tend to have excellent adhesion to the EVOH layer and / or the thermoplastic resin layer.

[0030] Examples of polyolefins containing carboxyl groups include polyolefins copolymerized with acrylic acid or methacrylic acid. In this case, all or part of the carboxyl groups contained in the polyolefin may be present in the form of a metal salt, as typified by ionomers. Examples of polyolefins having carboxylic anhydride groups include polyolefins graft-modified with maleic anhydride or itaconic acid. Examples of polyolefins having epoxy groups include polyolefins copolymerized with glycidyl methacrylate. Among these, preferred are polyolefins having carboxylic anhydride groups such as maleic anhydride, and particularly preferred are polyethylenes having carboxylic anhydride groups. These can be used alone or in combination of two or more.

[0031] The melt flow rate (MFR) of the adhesive resin measured according to JIS K7210:2014 (190°C, load 2160g) is not particularly limited, but is preferably 0.1 to 20.0g / 10min, more preferably 1.0 to 10.0g / 10min. When the MFR of the adhesive resin is within the above range, the molding stability tends to be better.

[0032] The content of the adhesive resin in the adhesive resin layer is not particularly limited, but the adhesive resin is preferably the main component (i.e., the content of the adhesive resin contained in the adhesive resin layer is 50% by mass or more). The content of the adhesive resin is more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, 90% by mass or more, 95% by mass or more, and 100% by mass is particularly preferred.

[0033] The adhesive resin layer may contain components other than the adhesive resin, such as antiblocking agents, processing aids, resins other than the adhesive resin, carboxylic acid compounds, phosphoric acid compounds, boron compounds, metal salts, stabilizers, antioxidants, UV absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, surfactants, drying agents, crosslinking agents, reinforcing agents such as various fibers, etc., within a range that does not impair the effects of the present invention, generally within a range of 20 mass % or less. These may be used alone or in combination of two or more kinds.

[0034] [Manufacturing method of the present tape] The method for producing the present tape is not particularly limited, and generally includes a method in which the raw material for forming the EVOH layer is extruded through a die and formed into a tape. In addition, when the present tape is a multi-layer tape having an EVOH layer and a thermoplastic resin layer, it can be manufactured by, for example, a method of laminating the raw materials forming each layer by co-extrusion from separate dies or a common die, a method of melt-extrusion laminating a thermoplastic resin to an EVOH layer, a method of melt-extrusion laminating an EVOH to a thermoplastic resin layer, a method of preparing an EVOH layer and a thermoplastic resin layer, coating them with a known adhesive such as an acrylic or silicone adhesive, and dry laminating them, etc. In addition, when the adhesive is used, it is preferable to use a crosslinking agent during coating to impart adhesiveness. In addition, other additives may be added to the adhesive depending on the application.

[0035] As the die, for example, a circular die or a T-die can be used. Examples of the molding method include extrusion molding, blow molding, injection molding, thermoforming, cast molding, and inflation molding.

[0036] In this manner, the present tape can be produced. In the production of the present tape, an aging step may be carried out as necessary. The produced present tape may be slit to a width suitable for use.

[0037] The thickness of the present tape is not particularly limited, but is preferably 10 to 400 μm, more preferably 15 to 200 μm, and particularly preferably 20 to 150 μm. When the thickness of the present tape is within the above range, it tends to have excellent flexibility.

[0038] Furthermore, when the present tape is a multilayer film, the ratio of the thickness of the EVOH layer to the thickness of the tape (EVOH layer / tape) is preferably 1 / 100 to 1 / 2, more preferably 1 / 80 to 1 / 3, even more preferably 1 / 50 to 1 / 4, and particularly preferably 1 / 30 to 1 / 10. When the thickness ratio of the present tape to the EVOH layer is within the above range, the gas barrier properties and flexibility tend to be excellent.

[0039] When the present tape has a thermoplastic resin layer, its thickness is not particularly limited, but from the viewpoints of industrial productivity and mechanical properties, it is preferably 7 to 100 μm, more preferably 10 to 50 μm. When the present tape has a plurality of thermoplastic resin layers, it is preferable that the total thickness of all the thermoplastic resin layers is in the above range.

[0040] When the present tape has an adhesive resin layer, its thickness is not particularly limited, but from the viewpoints of industrial productivity and quality stability, it is preferably 0.5 to 20 μm, more preferably 1 to 10 μm. When the present tape has a plurality of adhesive resin layers, it is preferable that the total thickness of all the adhesive resin layers is in the above range.

[0041] The oxygen permeability of this tape at a humidity of 65% and a temperature of 23°C is 0.15cc / m 2 ·day·atm or less is preferable, and 0.1cc / m 2It is more preferable that the oxygen permeability is equal to or less than 1·day·atm. Note that the oxygen permeability is a value calculated based on a thickness of the present tape of 20 μm.

[0042] The repulsive force of the present tape is preferably 1 N or less, more preferably 0.8 N or less, even more preferably 0.6 N or less, and particularly preferably 0.3 N or less. When the repulsive force is within the above range, the present tape tends to have excellent flexibility.

[0043] The repulsive force is measured according to the following measurement method. Cut this tape to a size of 8 cm x 6 cm, fold the long side in half, and clamp it in the chuck of a tensile tester. When the upper fixture of the tensile tester is brought close to the top end of the film and lowered 15 mm from the top end at a speed of 50 mm / min, measure the upward force received by the chuck of the tensile tester and use this as the repulsive force of the film (N).

[0044] The use of this tape is not particularly limited, but since it can achieve both high gas barrier properties and flexibility, it can be suitably used for protecting containers with gas barrier properties (for example, deep-draw containers and bag-in-boxes). In other words, if a container with gas barrier properties is damaged, it becomes difficult to maintain the gas barrier properties. Therefore, if a container with gas barrier properties is damaged, the gas barrier properties can be maintained by repairing it with this tape. The present tape can also be suitably used as an edge protection tape. The edge protection tape is used, for example, when a container or the like is manufactured using a laminate in which paper and a barrier film are bonded together, and the ends of the laminate need to be bonded together. In this case, the paper is exposed at the ends, which causes a decrease in gas barrier properties and causes liquids and the like to infiltrate into the container. Therefore, by bonding the present tape to the ends of such a container, it is possible to prevent the decrease in gas barrier properties and the infiltration of liquids and the like. EXAMPLES

[0045] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are based on mass.

[0046] Prior to the examples, the following EVOH was prepared. [EVOH] EVOH1 (ethylene content 25mol%, MFR 4g / 10min, density 1.23g / cm 3 ) EVOH2 (ethylene content 29mol%, MFR 4g / 10min, density 1.21g / cm 3 ) EVOH1' (ethylene content 32mol%, MFR 3g / 10min, density 1.19g / cm 3 ) EVOH2' (ethylene content 32mol%, MFR 3g / 10min, density 1.19(g / cm 3 )

[0047] <Example 1> A tape having a thickness of 30 μm was produced using EVOH1 by the T-die method under the following film-forming conditions. [Film forming conditions] Temperature:C1 / C2 / C3 / C4=180 / 210 / 220 / 220℃ Die temperature: 220℃ Rotation speed: 40 rpm

[0048] <Example 2> A tape was produced in the same manner as in Example 1, except that the EVOH used was EVOH2 and the thickness was changed to 50 μm.

[0049] <Comparative Example 1> A tape was produced in the same manner as in Example 1, except that the EVOH used was EVOH1' and the thickness was changed to 30 μm.

[0050] <Comparative Example 2> A tape was produced in the same manner as in Example 1, except that the EVOH used was changed to EVOH2' and the thickness was changed to 100 µm.

[0051] The following flexibility evaluation and gas barrier property evaluation were carried out using the obtained tapes of Examples 1 and 2 and Comparative Examples 1 and 2. The results are shown in Table 1 below.

[0052] [Flexibility evaluation] The tape was cut to 8cm x 6cm, the long side was folded in half, and clamped in the chuck of a tensile tester. The upper fixture of the tensile tester was brought close to the top end of the film, and the upward force received by the chuck of the tensile tester when it was lowered 15mm from the top end at a speed of 50mm / min was taken as the repulsive force of the tape (N), and evaluation was performed according to the following criteria. If the repulsive force (N) of the tape is low, it can be bent with less force, and therefore the film can be said to be highly flexible. [Evaluation Criteria] ◎: Repulsion force is less than 0.5N ○: Repulsion force is 0.5N or more but less than 1N △: Repulsive force is 1N or more but less than 2N ×: Repulsion force is 2N or more

[0053] [Gas Barrier Property Evaluation] Using an oxygen permeability measuring device (MOCON, "Ox-Tran2 / 21"), the oxygen permeability (cc / m2) of each tape at a humidity of 65% RH and a temperature of 23°C was measured. 2 The measured values ​​were converted to values ​​at a thickness of 20 μm to eliminate the influence of thickness, and the values ​​were evaluated according to the following evaluation criteria. [Evaluation Criteria] 〇: Oxygen permeability is 0.1cc / m 2 Less than .day.atm ×: Oxygen permeability is 0.1cc / m 2 .day.atm super

[0054] [Table 1]

[0055] From the results in Table 1, the tapes of Examples 1 and 2, which used EVOH with an ethylene content of less than 32 mol%, achieved both high gas barrier properties and flexibility. On the other hand, the tape of Comparative Example 1, which used EVOH with an ethylene content of 32 mol and had a thickness of 30 μm, did not have sufficient gas barrier properties. Moreover, the tape of Comparative Example 2, which used EVOH with an ethylene content of 32 mol and had a thickness of 100 μm, had high gas barrier properties but lacked flexibility. [Industrial Applicability]

[0056] Because this tape combines high gas barrier properties with flexibility, it can be ideally used to protect containers with gas barrier properties (e.g., deep-draw containers and bag-in-boxes) and as a tape for protecting the edges of paper containers to which a gas barrier film is attached.

Claims

1. A tape having an ethylene-vinyl alcohol copolymer layer containing an ethylene-vinyl alcohol copolymer having an ethylene content of 20 mol % or more and less than 32 mol %.

2. 2. The tape according to claim 1, wherein the ethylene-vinyl alcohol copolymer layer has a thickness of 0.1 to 80 μm.

3. 3. The tape according to claim 1, wherein the ethylene-vinyl alcohol copolymer has an ethylene content of 20 mol % or more and 30 mol % or less.

4. 3. The tape according to claim 1, wherein the ethylene-vinyl alcohol copolymer has a melt flow rate (210° C., load 2160 g) of 2 to 15 g / 10 min.

5. 3. The tape according to claim 1, wherein the ethylene-vinyl alcohol copolymer content in the ethylene-vinyl alcohol copolymer layer is 50% by mass or more.

6. 3. The tape according to claim 1 or 2, which has a thickness of 10 to 400 μm.

7. 3. The tape according to claim 1, wherein the ratio of the thickness of the ethylene-vinyl alcohol copolymer layer to the thickness of the tape (ethylene-vinyl alcohol copolymer layer / tape) is 1 / 100 to 1 / 2.

8. 3. The tape according to claim 1 or 2, which is used for protecting a container having gas barrier properties.

9. 3. The tape according to claim 1 or 2, which is used for edge protection.

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