Composition, multilayer structure, molded body, packaging material container, and method for producing composition

Abstract

In order to provide a composition excellent in both thermal stability and prevention of coloration by heating, this composition contains an ethylene-vinyl alcohol copolymer (A), a copolymer (B) containing an ethylene structural unit and a structural unit represented by formula (1), and a titanium compound (C). The content of the titanium compound (C) in the composition is 0.001 ppm by mass or more and less than 10 ppm by mass in terms of metal.

Description

Composition, multilayer structure, molded body, packaging material container, and method for producing composition

[0001] The present invention relates to a composition, a multilayer structure, a molded article, a packaging material container, and a method for producing the composition.

[0002] Ethylene-vinyl alcohol copolymer (hereinafter, sometimes referred to as "EVOH") is widely used as a thermoplastic resin because it has excellent oil resistance, organic solvent resistance, rigidity, hardness, abrasion resistance, gas barrier properties, and the like compared to other resins.

[0003] Numerous EVOHs have been proposed that have been improved in various performance aspects depending on the application. For example, Patent Documents 1 and 2 propose EVOHs that have improved impact resistance and flowability without impairing these desirable properties. Patent Documents 3 and 4 propose EVOHs that have improved long-run moldability and flex fatigue resistance. Patent Document 5 proposes EVOHs that have improved adhesion to hydrophobic thermoplastic resins without impairing gas barrier properties.

[0004] Japanese Patent Publication No. 42-3185 Japanese Patent Publication No. 5-2699 Japanese Patent No. 4642195 Japanese Patent Laid-Open No. 2001-288323 Japanese Patent No. 5610955

[0005] Although the performance of each of the EVOHs described in Patent Documents 1 to 5 has been improved depending on the application, there is still room for improvement in terms of achieving both thermal stability and suppression of discoloration due to heating. Under these circumstances, the present invention provides a composition that is excellent in both thermal stability and suppression of discoloration due to heating.

[0006] However, the present inventors have conducted extensive research in light of the above circumstances and have found that an EVOH composition excellent in both thermal stability and suppression of discoloration due to heating can be obtained by providing a composition containing EVOH (A), a copolymer (B) containing ethylene structural units and structural units represented by formula (1) described below, and a titanium compound (C), wherein the content of the titanium compound (C) in terms of metal is 0.001 ppm by mass or more and less than 10 ppm by mass of the composition.

[0007] That is, the present invention has the following aspects: [1] A composition comprising EVOH (A), a copolymer (B) containing an ethylene structural unit and a structural unit represented by the following formula (1), and a titanium compound (C), wherein the content of the titanium compound (C) in the composition is 0.001 ppm by mass or more and less than 10 ppm by mass in terms of metal: [2] R represented by the formula (1) Ａis a hydrogen atom or an aliphatic hydrocarbon group having 1 to 4 carbon atoms. [3] The composition according to [1] or [2], wherein the copolymer (B) comprises an ethylene-vinyl carboxylic acid ester copolymer and / or an ethylene-acrylic acid ester copolymer (B1). [4] The composition according to any one of [1] to [3], wherein the copolymer (B) comprises an ethylene-vinyl carboxylic acid ester copolymer and / or an ethylene-acrylic acid ester copolymer (B1), and at least one copolymer (B2) selected from the group consisting of an ethylene-vinyl carboxylic acid ester copolymer having a polar group, an ethylene-acrylic acid ester copolymer having a polar group, an ethylene-vinyl carboxylic acid ester-maleic anhydride copolymer, and an ethylene-acrylic acid ester-maleic anhydride copolymer. [5] The composition according to [4], wherein the polar group in the ethylene-vinyl carboxylic acid ester copolymer having a polar group is a carboxy group or a carbonyloxycarbonyl group. [6] The composition according to [4] or [5], wherein the copolymer (B) is an ethylene-vinyl carboxylate copolymer having a polar group and / or an ethylene-acrylic acid ester copolymer having a polar group, and at least one of the polar groups is a carboxy group. [7] The composition according to [5], wherein the carbonyloxycarbonyl in the carbonyloxycarbonyl group is maleic anhydride. [8] The composition according to any one of [1] to [7], wherein the content of the titanium compound (C) in the composition is 0.001 ppm by mass or more and 5 ppm by mass or less. [9] The composition according to any one of [1] to [8], wherein the mass ratio (A / B) of the EVOH (A) to the copolymer (B) is 70 / 30 to 99 / 1.

[10] The composition according to any one of [1] to [9], wherein the mass ratio (A / B) of the EVOH (A) to the copolymer (B) is 70 / 30 to 85 / 15.

[11] The composition according to [4] or [5], wherein the mass ratio (B2 / B1) of the copolymer (B2) to the copolymer (B1) is 0.01 to 10.

[12] The composition according to [4] or [5], wherein the mass ratio [A / (B1+B2)] of EVOH (A) to the total mass of the copolymer (B1) and the copolymer (B2) is 50 / 50 to 99 / 1.

[13] A composition for recycling, wherein the composition according to any one of [1] to

[12] is for recycling.

[14] A regrind layer comprising the composition according to any one of [1] to

[12] .

[15] A multilayer structure having a layer comprising the composition according to any one of [1] to

[12] .

[16] The multilayer structure according to

[15] , further comprising an adhesive resin layer.

[17] A molded article obtained by molding the multilayer structure according to

[15] or

[16] .

[18] A packaging material container obtained by molding the multilayer structure according to

[15] .

[19] A method for producing the composition according to any one of [1] to

[12] , comprising the step of mixing the EVOH (A), the copolymer (B), and the titanium compound (C).

[20] A method for producing the composition according to [4] or [5], comprising a step of mixing the EVOH (A), the copolymer (B1), the copolymer (B2), and the titanium compound (C).

[21] A method for producing a multilayer structure, comprising a step of obtaining a composition by the method for producing a composition according to

[19] or

[20] , and a step of forming a layer containing the composition obtained by the step as at least one layer of the multilayer structure.

[0008] The present invention provides a composition containing EVOH (A), a copolymer (B) containing ethylene structural units and structural units represented by formula (1) described below, and a titanium compound (C), wherein the content of the titanium compound (C) in terms of metal is set to a specific trace amount of 0.001 ppm by mass or more and less than 10 ppm by mass of the composition, thereby providing excellent thermal stability and suppressing discoloration due to heating. Therefore, the composition can be suitably used as an EVOH resin layer in a multilayer structure in which resins with different properties are laminated.

[0009] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0010] In the present invention, "X and / or Y (X and Y are any configuration)" means at least one of X and Y, and can mean three possibilities: X only, Y only, or X and Y. When expressed as "x to y" (x and y are any numbers), unless otherwise specified, it also means "x or more and y or less," as well as "preferably greater than x" or "preferably less than y." When expressed as "x or more" (x is any number) or "y or less" (y is any number), it also means "preferably greater than x" or "preferably less than y." Furthermore, for numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in one stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples.

[0011] In the present invention, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate. Furthermore, "acrylic resin" refers to a resin obtained by polymerizing a copolymerization component containing at least one (meth)acrylate monomer. In the present invention, "main component" refers to a component that has a significant effect on the properties of the target object, and the content of the component is usually 50% by mass or more, preferably 55% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, of the target object, and may even be 100% by mass.

[0012] An EVOH composition according to one embodiment of the present invention (hereinafter sometimes referred to as "the EVOH composition") contains EVOH (A) (hereinafter sometimes referred to as "component A"), a copolymer (B) (hereinafter sometimes referred to as "component B") containing an ethylene structural unit and a structural unit represented by the following formula (1), and a titanium compound (C) (hereinafter sometimes referred to as "component C"), and the content of the titanium compound (C) in terms of metal is set to be 0.001 ppm by mass or more and less than 10 ppm by mass of the EVOH composition. Each component will be described below.

[0013] <Component A> The EVOH (A) used in the present EVOH composition is typically a resin obtained by copolymerizing ethylene with a vinyl ester monomer and then saponifying the copolymer, and is a water-insoluble thermoplastic resin known as a saponified ethylene-vinyl alcohol copolymer or ethylene-vinyl acetate copolymer. Any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, can be used, but solution polymerization using methanol as a solvent is generally used. The resulting ethylene-vinyl ester copolymer can also be saponified by a known method.

[0014] That is, the EVOH (A) used in the present invention is composed mainly of ethylene structural units and vinyl alcohol structural units, and also contains a small amount of vinyl ester structural units that remain unsaponified. EVOH is also generally called a "saponified ethylene-vinyl ester copolymer."

[0015] Vinyl acetate is typically used as the vinyl ester monomer because of its ease of commercial availability and the efficiency of treating impurities during production. Other vinyl ester monomers include, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Among these, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms. These monomers are typically used alone, but multiple types may be used simultaneously as needed.

[0016] The content of ethylene structural units in the EVOH (A) is usually 20 to 60 mol%, preferably 21 to 55 mol%, more preferably 22 to 50 mol%, and particularly preferably 23 to 45 mol%, as measured in accordance with ISO 14663. When the content is equal to or greater than the lower limit, the gas barrier property and melt moldability at high humidity tend to be excellent, and when the content is equal to or less than the upper limit, the gas barrier property tends to be excellent.

[0017] The degree of saponification of the vinyl ester component in the EVOH (A), as measured in accordance with JIS K6726 (wherein the EVOH is a solution uniformly dissolved in a water / methanol solvent), is usually 90 to 100 mol%, preferably 95 to 100 mol%, and particularly preferably 99 to 100 mol%. When the degree of saponification is equal to or greater than the lower limit, the EVOH tends to have excellent gas barrier properties, thermal stability, moisture resistance, etc.

[0018] The melt flow rate (MFR) (210°C, load 2160 g) of the EVOH (A) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and particularly preferably 3 to 35 g / 10 min. When the MFR is equal to or less than the upper limit, excellent film-forming properties tend to be obtained. When the MFR is equal to or more than the lower limit, melt extrusion tends to be easy.

[0019] The EVOH (A) used in the present EVOH composition may further contain structural units derived from the following comonomers in addition to ethylene structural units and vinyl alcohol structural units (including unsaponified vinyl ester structural units). Examples of the comonomer include α-olefins such as propylene, isobutene, α-octene, α-dodecene, and α-octadecene; hydroxyl-containing α-olefins such as 3-buten-1-ol, 4-penten-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; styrene, etc. These may be used alone or in combination of two or more.

[0020] Furthermore, as the EVOH (A), EVOH that has been "post-modified" by urethanization, acetalization, cyanoethylation, oxyalkylenation, or the like can also be used.

[0021] Among the modified EVOHs (A) as described above, EVOHs (A) in which primary hydroxyl groups have been introduced into the side chains by copolymerization are preferred in that they have good secondary formability in stretching treatments and vacuum / pressure forming, etc., and EVOHs (A) having a 1,2-diol structure in the side chains are particularly preferred.

[0022] Furthermore, the EVOH (A) used in the present EVOH composition may be a mixture with a different other EVOH. Examples of such other EVOH include EVOHs having a different content of ethylene structural units, a different degree of saponification, a different melt flow rate (MFR) (210°C, load 2160 g), a different other copolymerization component, and a different degree of modification (for example, EVOHs having a different content of structural units containing a primary hydroxyl group in the side chain).

[0023] The content of EVOH (A) in the present EVOH composition is not particularly limited, but it is preferable that EVOH (A) is the main component (i.e., the content of EVOH (A) in the present EVOH composition is 50% by mass or more), more preferably 55% by mass or more, even more preferably 60% by mass or more, particularly preferably 70% by mass or more, especially preferably 80% by mass or more, and most preferably 90% by mass or more.

[0024] <Component B> Component B used in the present EVOH composition together with the EVOH (A) is a copolymer (B) containing an ethylene structural unit and a structural unit represented by the following formula (1). The present EVOH composition has excellent mechanical strength and flexibility due to the inclusion of Component B. From this perspective, a multilayer structure containing the present EVOH composition tends to exhibit excellent mechanical strength even without containing a resin such as PA, PVDC, PET, PVOH, or PVC, which generally has excellent mechanical strength.

[0025] The B component is generally R represented by formula (1) Ａ is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 20 carbon atoms, but from the viewpoint of structural stability, R Ａ is preferably a hydrogen atom or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and R １ When R is an acyloxy group, it is preferably an ethylene-vinyl carboxylic acid ester copolymer, and １ is an alkoxycarbonyl group, an ethylene-acrylic acid ester copolymer is more preferred. These are usually used alone, but multiple types may be used simultaneously as needed, and may contain, for example, an ethylene-carboxylic acid vinyl ester copolymer and / or an ethylene-acrylic acid ester copolymer (B1) (hereinafter sometimes referred to as "component B1").

[0026] The density of the component B is a value measured in accordance with JIS K7112, and is usually 0.85 to 0.99 g / cm ３ and preferably 0.86 to 0.98 g / cm ３ , more preferably 0.87 to 0.97 g / cm ３When the density is set within the above range, the effects of the present invention tend to be further enhanced.

[0027] The content of Component B in the EVOH composition is not particularly limited, but is preferably 50% by mass or less, more preferably 45% by mass or less, particularly preferably 40% by mass or less, especially preferably 35% by mass or less, and most preferably 30% by mass or less, based on the EVOH composition. The lower limit of the content is usually 1% by mass or more, preferably 15% by mass or more, and especially preferably 20% by mass or more. That is, the content of Component B in the EVOH composition is preferably 1 to 50% by mass, more preferably 5 to 45% by mass, particularly preferably 10 to 40% by mass, especially preferably 15 to 35% by mass, and most preferably 20 to 30% by mass.

[0028] The mass ratio (A / B) of EVOH (component A) to component B is preferably 50 / 50 to 99 / 1, more preferably 70 / 30 to 85 / 15, and particularly preferably 70 / 30 to 80 / 20. When the mass ratio (A / B) is within the above range, the thermal stability tends to be better.

[0029] <Component B1> The ethylene-vinyl carboxylate copolymer is a resin obtained by copolymerizing ethylene with a vinyl carboxylate monomer, and the ethylene-acrylic acid ester copolymer is a resin obtained by copolymerizing ethylene with an acrylic acid ester monomer.

[0030] The vinyl carboxylate monomer is not particularly limited as long as it is a conventionally known monomer, but for example, the acyloxy group in the vinyl carboxylate monomer has 1 to 18 carbon atoms, more preferably 2 to 8 carbon atoms, and particularly preferably 2 to 6 carbon atoms. These are usually used alone, but multiple types may be used simultaneously as necessary. In terms of ease of commercial availability and the efficiency of treating impurities during production, it is typically preferred to use vinyl acetate.

[0031] The acrylic acid ester monomer is not particularly limited as long as it is a conventionally known monomer, but for example, the number of carbon atoms in the alkoxycarbonyl group in the acrylic acid ester monomer is preferably 1 to 18, more preferably 2 to 8, and particularly preferably 2 to 6. Among these, from the viewpoints of excellent copolymerizability and coating strength, ease of handling, and ease of raw material availability, aliphatic (meth)acrylic acid ester monomers, typically methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate, are preferably used, and particularly preferably methyl (meth)acrylate and ethyl (meth)acrylate are used. These are usually used alone, but multiple types may be used simultaneously if necessary.

[0032] Specific examples of the B1 component include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), and ethylene-ethyl acrylate copolymer (EEA).

[0033] The melt flow rate (MFR) (190°C, 2160 g load) of the ethylene-vinyl carboxylate copolymer is usually 0.5 to 50 g / 10 min, preferably 0.5 to 20 g / 10 min, more preferably 1 to 10 g / 10 min, particularly preferably 2 to 9 g / 10 min, and most preferably 3 to 8 g / 10 min. When the MFR is within the above range, there is a tendency for the thermal stability to be further improved.

[0034] The ethylene-vinyl carboxylate ester copolymer preferably has a vinyl carboxylate monomer content of 1 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 7 to 35% by mass. When the vinyl carboxylate monomer content is set within the above range, a good balance between flexibility and heat resistance tends to be achieved.

[0035] The MFR (190°C, load 2160 g) of the ethylene-acrylic acid ester copolymer is usually 0.5 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, more preferably 1 to 35 g / 10 min, particularly preferably 2 to 20 g / 10 min, and especially preferably 3 to 15 g / 10 min. When the MFR is within the above range, there is a tendency for the thermal stability to be further improved.

[0036] The acrylic acid ester monomer content of the ethylene-acrylic acid ester copolymer is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 10 to 30% by mass. When the acrylic acid ester monomer content is set within the above range, a good balance between flexibility and durability tends to be achieved.

[0037] The content of Component B1 in the EVOH composition is not particularly limited, but is preferably 30% by mass or less, more preferably 25% by mass or less, particularly preferably 20% by mass or less, especially preferably 15% by mass or less, and most preferably 10% by mass or less, based on the EVOH composition. The lower limit of the content is usually 0.1% by mass or more, preferably 0.5% by mass or more, and especially preferably 1% by mass or more. That is, when Component B1 is contained in the EVOH composition, the content of Component B1 is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, particularly preferably 1 to 20% by mass, especially preferably 1 to 15% by mass, and most preferably 1 to 10% by mass.

[0038] The mass ratio (A / B1) of EVOH (component A) to component B1 is preferably 70 / 30 to 99 / 1, more preferably 70 / 30 to 85 / 15, and particularly preferably 70 / 30 to 80 / 20. When the mass ratio (A / B1) is within the above range, the thermal stability tends to be better.

[0039] <Component B2> The EVOH composition of the present invention more preferably contains, as Component B used together with the EVOH (Component A), an ethylene-vinyl carboxylate copolymer and / or an ethylene-acrylic acid ester copolymer (Component B1), as well as at least one copolymer (Component B2) selected from the group consisting of an ethylene-vinyl carboxylate copolymer having a polar group, an ethylene-acrylic acid ester copolymer having a polar group, an ethylene-vinyl carboxylate-maleic anhydride copolymer, and an ethylene-acrylic acid ester-maleic anhydride copolymer. That is, the at least one copolymer used as component B2 selected from the group consisting of an ethylene-carboxylic acid vinyl ester copolymer having a polar group, an ethylene-acrylic acid ester copolymer having a polar group, an ethylene-carboxylic acid vinyl ester-maleic anhydride copolymer, and an ethylene-acrylic acid ester-maleic anhydride copolymer is one obtained by modifying a resin obtained by copolymerizing ethylene with a carboxylic acid vinyl ester monomer so as to have a polar group, one obtained by copolymerizing ethylene with a monomer having a polar group as a carboxylic acid vinyl ester monomer, one obtained by copolymerizing a resin obtained by copolymerizing ethylene with an acrylic acid ester monomer using a monomer having a polar group, or one obtained by copolymerizing ethylene with a monomer having a polar group.

[0040] The carboxylic acid vinyl ester monomers described in the B1 component can be used as the carboxylic acid vinyl ester monomers. These are usually used alone, but multiple types may be used simultaneously if necessary. The acrylic acid ester monomers described in the B1 component can be used as the acrylic acid ester monomers. These are usually used alone, but multiple types may be used simultaneously if necessary. The polar group in the polar group-containing monomer is preferably a carboxy group and / or a carbonyloxycarbonyl group, and more preferably a carbonyloxycarbonyl group. Examples of monomers having a carboxy group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, and citraconic acid. Examples of monomers having a carbonyloxycarbonyl group include maleic anhydride. These may be used alone or in combination of two or more types.

[0041] The melt flow rate (MFR) (190°C, 2160 g load) of the ethylene-vinyl carboxylate copolymer having a polar group is usually 0.5 to 50 g / 10 min, preferably 0.5 to 30 g / 10 min, particularly preferably 1 to 20 g / 10 min, and especially preferably 3 to 20 g / 10 min. When the MFR is within the above range, there is a tendency for the thermal stability to be further improved.

[0042] The MFR (190°C, load 2160 g) of the ethylene-acrylic acid ester copolymer having a polar group is usually 0.5 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, particularly preferably 1 to 35 g / 10 min, particularly preferably 1 to 20 g / 10 min, and most preferably 3 to 20 g / 10 min. When the MFR is within the above range, there is a tendency for the thermal stability to be further improved.

[0043] The MFR (190°C, load 2160 g) of the ethylene-vinyl carboxylate-maleic anhydride copolymer is usually 0.5 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, particularly preferably 1 to 35 g / 10 min, particularly preferably 1 to 20 g / 10 min, and most preferably 3 to 20 g / 10 min. When the MFR is within the above range, there is a tendency for the thermal stability to be further improved.

[0044] The MFR (190°C, load 2160 g) of the ethylene-acrylic acid ester-maleic anhydride copolymer is usually 0.5 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, particularly preferably 1 to 35 g / 10 min, particularly preferably 1 to 20 g / 10 min, and most preferably 3 to 20 g / 10 min. When the MFR is within the above range, there is a tendency for the thermal stability to be further improved.

[0045] The density of the B2 component is a value measured in accordance with JIS K7112, and is usually 0.85 to 0.99 g / cm ３ and preferably 0.86 to 0.98 g / cm ３ , more preferably 0.87 to 0.97 g / cm ３ When the density is set within the above range, the effects of the present invention tend to be further enhanced.

[0046] Specific examples of component B2 include ethylene-vinyl carboxylate ester copolymers having a polar group, such as maleic anhydride EVA. Examples of ethylene-acrylic acid ester copolymers having a polar group include ethylene maleic anhydride-ethyl acrylate copolymers. Examples of ethylene-vinyl carboxylate ester-maleic anhydride copolymers include ethylene-vinyl acetate-maleic anhydride terpolymers. Examples of ethylene-acrylic acid ester-maleic anhydride copolymers include ethylene-methyl acrylate-maleic anhydride terpolymers, ethylene-ethyl acrylate-maleic anhydride terpolymers, and ethylene-butyl acrylate-maleic anhydride terpolymers.

[0047] The content of the B2 component is not particularly limited, but is preferably 30% by mass or less, more preferably 25% by mass or less, particularly preferably 20% by mass or less, especially preferably 15% by mass or less, and most preferably 10% by mass or less, based on the EVOH composition. The lower limit of the content is usually 0.1% by mass or more, preferably 0.5% by mass or more, and especially preferably 1% by mass or more. That is, when the EVOH composition contains the B2 component, the content of the B2 component is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, particularly preferably 1 to 20% by mass, especially preferably 1 to 15% by mass, and most preferably 1 to 10% by mass.

[0048] The mass ratio (A / B2) of EVOH (component A) to component B2 is preferably 70 / 30 to 99 / 1, more preferably 70 / 30 to 85 / 15, and particularly preferably 70 / 30 to 80 / 20. By setting the mass ratio (A / B2) within the above range, the thermal stability tends to be more excellent.

[0049] The mass ratio of the B2 component to the B1 component (B2 / B1) is preferably 0.01 to 10, more preferably 0.01 to 1, even more preferably 0.02 to 0.8, particularly preferably 0.03 to 0.5, especially preferably 0.05 to 0.25, and most preferably 0.1 to 0.23. By setting the mass ratio (B2 / B1) within the above range, the thermal stability tends to be more excellent.

[0050] Furthermore, the mass ratio of EVOH (component A) to the total mass of component B1 and component B2, [A / (B1+B2)], is preferably 50 / 50 to 99 / 1, more preferably 70 / 30 to 85 / 15, and particularly preferably 70 / 30 to 80 / 20. By setting the mass ratio [A / (B1+B2)] within the above range, there is a tendency for the thermal stability to be even more excellent.

[0051] <Component C> Examples of the titanium compound (C) used in the present EVOH composition include inorganic titanium compounds and organic titanium compounds. The titanium compounds (C) may be used alone or in combination of two or more, as long as titanium is contained in the composition. Among these, inorganic titanium compounds are preferred as the titanium compound (C). The presence or absence and content of such titanium can be determined, for example, by ICP mass spectrometry.

[0052] Examples of the inorganic titanium compounds include titanium oxide, titanium hydroxide, titanium chloride, and inorganic salts of titanium. Examples of the titanium oxides include titanium(II) oxide, titanium(III) oxide, titanium(IV) oxide, and titanium suboxide. Examples of the titanium hydroxides include titanium(I) hydroxide and titanium(II) hydroxide. Examples of the titanium chlorides include titanium(I) chloride and titanium(II) chloride. Examples of the inorganic salts of titanium include titanium phosphate and titanium sulfate. Among these, titanium oxide is preferred, titanium(IV) oxide is more preferred, and rutile titanium(IV) oxide is particularly preferred.

[0053] Examples of the organic titanium compounds include titanium carboxylates such as titanium acetate, titanium butyrate, and titanium stearate.

[0054] The titanium compound (C) may exist in the EVOH composition as a titanium compound, or may exist in an ionized state or in the form of a complex interacting with the EVOH resin or other ligands.

[0055] The average particle size of the titanium compound (C) is usually 0.001 to 100 μm, preferably 0.01 to 50 μm, and more preferably 0.015 to 20 μm. When the average particle size of the titanium compound (C) is within the above range, the coloration suppression effect tends to be excellent.

[0056] The content of the titanium compound (C) in terms of metal is from 0.001 ppm by mass to less than 10 ppm by mass per mass of the EVOH composition. It is preferably from 0.01 ppm by mass to less than 5 ppm by mass, more preferably from 0.01 to 3 ppm by mass, even more preferably from 0.03 to 1 ppm by mass, and particularly preferably from 0.05 to 0.5 ppm by mass. By setting the content of the titanium compound (C) within the above range, discoloration due to thermal degradation during melt molding can be suppressed, resulting in excellent long-run properties. Furthermore, by setting the content of the titanium compound (C) at or above the lower limit, excellent suppression of discoloration can be achieved, while by setting the content at or below the upper limit, thermal decomposition of the EVOH (A) is suppressed and discoloration is less likely to occur. The metal-equivalent content of the titanium compound (C) refers to the content of elemental titanium.

[0057] The content of the titanium compound (C) calculated as metal can be determined by weighing out the EVOH composition into a platinum crucible, ashing it successively with a burner and an electric furnace, thermally decomposing the ashed material with nitric acid and hydrofluoric acid, treating it with a mixed acid of dilute nitric acid and dilute hydrofluoric acid, and measuring the titanium in the resulting constant-volume solution by ICP mass spectrometry using an ICP mass spectrometer (Agilent 8800, manufactured by Agilent Technologies).

[0058] Generally, EVOH (A) becomes discolored due to thermal degradation. This is thought to be because EVOH (A) deteriorates due to heat, generating radicals, which dehydrate the hydroxyl groups of EVOH (A), forming double bonds in the main chain of EVOH (A). These sites act as reaction initiation sites, further accelerating dehydration and forming a conjugated polyene structure in the main chain of EVOH (A). In contrast, the present EVOH composition contains a specific trace amount of titanium compound (C), which suppresses discoloration of EVOH (A) due to thermal degradation and provides excellent long-run properties. Furthermore, in the present EVOH composition, the copolymer (B) component containing ethylene structural units and structural units represented by formula (1) has excellent compatibility with EVOH (A), resulting in excellent mechanical strength of multilayer structures and molded articles containing the EVOH composition. It is generally believed that the inclusion of titanium compound (C) in an EVOH composition will cause discoloration of the EVOH composition due to titanium ions, and it is common technical knowledge for those skilled in the art to avoid the use of titanium compound (C). However, in the present invention, contrary to this common technical knowledge, it has been discovered that when a specific trace amount of titanium compound (C) is used, an EVOH composition in which discoloration due to thermal degradation is suppressed can be obtained. That is, titanium is stable as a tetravalent ion, and even in a trace amount, it is presumed that titanium coordinates to the double bonds in the main chain of the EVOH (A) as described above, forms a chelate, and stabilizes the EVOH, thereby suppressing the formation of a polyene structure.

[0059] <Method for Producing EVOH Composition> The EVOH composition can be produced, for example, by mixing the EVOH (component A), a copolymer (component B) containing ethylene structural units and structural units represented by formula (1), and a titanium compound (component C) by a known method, such as dry blending, melt mixing, solution mixing, or impregnation. Among these, a method including a step of melt-mixing the raw composition materials containing components A to C is preferred. These production methods can also be arbitrarily combined. Components A to C may be mixed all at once, or they may be mixed in multiple batches, for example, by first mixing components A and B and then mixing component C with the mixture of components A and B. In the case of components B1 and B2, components A and B1 may be mixed first, and then components B2 and C may be mixed with the mixture of components A and B1.

[0060] The dry blending method may be, for example, (i) a method in which a pellet-like mixture of components A and B and a titanium compound (C) are dry blended using a tumbler or the like.

[0061] Examples of the melt-mixing method include (ii) a method in which a pellet-like mixture of components A and B is dry-blended with a titanium compound (C), and the resulting dry blend is melt-kneaded; and (iii) a method in which titanium compound (C) is added to a molten mixture of components A and B, and the mixture is melt-kneaded.

[0062] Examples of the solution mixing method include (iv) a method in which a solution is prepared using commercially available A and B components, a titanium compound (C) is blended therein, the mixture is coagulated and molded, and then the mixture is subjected to solid-liquid separation by known means and dried; and (v) a method in which, in the production process of EVOH (A), a titanium compound (C) is added to a solution of an ethylene-vinyl ester copolymer before saponification or a homogeneous solution of EVOH (A) (such as a water / alcohol solution), the mixture is coagulated and molded, and then the mixture is subjected to solid-liquid separation by known means and dried.

[0063] Examples of the impregnation method include (vi) a method in which a pellet-shaped mixture of components A and B is contacted with an aqueous solution containing titanium compound (C) to incorporate titanium compound (C) into the mixture of components A and B, followed by drying. The aqueous solution containing titanium compound (C) can be an aqueous solution of titanium compound (C) or a titanium compound (C) obtained by immersing the titanium compound (C) in water containing various chemicals to elute titanium ions. In the impregnation method, the content of titanium compound (C) (metal equivalent) can be controlled by the concentration of titanium compound (C) in the aqueous solution in which the mixture of components A and B is immersed, as well as the immersion temperature, immersion time, and other factors. The immersion temperature and immersion time are typically 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is typically 10 to 40°C, preferably 20 to 35°C.

[0064] As the drying method in each of the above-mentioned production methods, various drying methods can be used, and either static drying or fluidized drying may be used, or these may be used in combination.

[0065] As mentioned above, in the present invention, the above-mentioned different methods can be combined. Among them, the melt mixing method is preferred, and method (ii) is particularly preferred, in terms of productivity and the fact that a composition can be obtained that is more effective in the present invention. Furthermore, when the above-mentioned other thermoplastic resins and other compounding agents are used, they may be compounded by a conventional method according to the above-mentioned production method.

[0066] The EVOH composition obtained by each of the above-mentioned production methods may have any shape, but is preferably in the form of pellets. The pellets may be, for example, spherical, oval, cylindrical, cubic, or rectangular, but are typically oval or cylindrical. From the viewpoint of convenience when subsequently used as a molding material, the size of the pellets is such that, in the case of an oval shape, the minor axis is typically 1 to 10 mm, preferably 2 to 6 mm, and more preferably 2.5 to 5.5 mm, and the major axis is typically 1.5 to 30 mm, preferably 3 to 20 mm, and more preferably 3.5 to 10 mm. Furthermore, in the case of a cylindrical shape, the diameter of the base is typically 1 to 6 mm, preferably 2 to 5 mm, and the length is typically 1 to 6 mm, preferably 2 to 5 mm. The shape and size of the pellet-like mixture of components A and B used in each of the above-mentioned production methods are also preferably similar.

[0067] The present EVOH composition is inhibited from changing in color even when heated during melt molding, and has excellent long-run properties, and the difference between the YI value (yellow index) before heating and the YI value after heating (YI value after heating - YI value before heating) is usually less than 22.5, preferably 22 or less, and particularly preferably 21 or less. When the difference between the YI value before heating and the YI value after heating is within the above range, there is a tendency for it to be judged that discoloration due to heating is inhibited.

[0068] The YI value before heating is obtained by crushing the present EVOH composition into 1 to 5 mm square pieces, filling the crushed pieces into a cylinder having an inner diameter of 32 mm and a height of 30 mm, scraping them, and measuring the YI value using a spectrophotometer SE6000 (manufactured by Nippon Denshoku Industries Co., Ltd.) The YI value after heating is obtained by heating the present EVOH composition crushed into 1 to 5 mm square pieces in an oven in an air atmosphere at 150°C for 5 hours, and measuring the YI value in the same manner.

[0069] The water content of the present EVOH composition is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and particularly preferably 0.1 to 0.3% by mass.

[0070] The moisture content of the EVOH composition is measured and calculated by the following method: The mass (W1) of the EVOH composition before drying is weighed on an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then cooled in a desiccator for 30 minutes, after which the mass (W2) is weighed and calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] x 100

[0071] The EVOH composition thus obtained is prepared into various forms, such as pellets, powder, or liquid, and provided as a material for various molded articles and multilayer structures. Furthermore, because the EVOH composition has excellent thermal stability and coloration suppression, molded articles made using the EVOH composition or multilayer structures having layers made using the EVOH composition have the advantage of being less susceptible to deterioration in quality, such as thermal degradation, even when recycled, which involves thermal history. In particular, the present invention is preferably provided as a material for melt molding, since the effects of the present invention tend to be more efficiently achieved. The present EVOH composition also includes compositions obtained by blending resins other than the components (A), (B), and (C) used in the EVOH composition.

[0072] When the EVOH composition is in the form of pellets, it is also preferable to apply a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of types of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters of higher fatty acids, etc.), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, etc.; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide, etc.; bis-higher fatty acid amides such as ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, ethylene bislauric acid amide, etc.), low-molecular-weight polyolefins (e.g., low-molecular-weight polyethylene or low-molecular-weight polypropylene having a molecular weight of about 500 to 10,000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, and fluorinated ethylene resins. These compounds may be used alone or in combination of two or more. The content of such lubricants in the EVOH composition is usually 5% by mass or less, preferably 1% by mass or less. The lower limit is usually 0% by mass.

[0073] Examples of molded articles in which the present EVOH composition is used as a molding material include monolayer films molded from the present EVOH composition, and multilayer structures having at least one layer containing the present EVOH composition, which is also suitable as a regrind layer since the present EVOH composition is also suitable as a recycled composition that is subjected to thermal history.

[0074] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure") has at least one layer containing the EVOH composition. The layer containing the EVOH composition (hereinafter sometimes simply referred to as "the EVOH composition layer") can be laminated with another substrate containing a thermoplastic resin other than the EVOH composition as a main component (hereinafter the resin used in the substrate will be referred to as "substrate resin") to impart additional strength, protect the EVOH composition layer from the effects of moisture, etc., or impart other functions.

[0075] Examples of the base resin include polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene-based resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin-based resins such as polybutene, polypentene, and polycyclic olefin-based resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain); and polyolefins obtained by dissolving these polyolefins in an unsaturated carboxylic acid or Examples include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with an ester thereof, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These may be used alone or in combination of two or more.

[0076] Of these, hydrophobic resins such as polyamide-based resins, polyolefin-based resins, polyester-based resins, and polystyrene-based resins are preferred, and more preferred are polyolefin-based resins such as polyethylene-based resins, polypropylene-based resins, polycyclic olefin-based resins, and unsaturated carboxylic acid-modified polyolefin-based resins thereof.

[0077] The layer structure of the present multilayer structure can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, or b2 / b1 / a / b1 / a / b1 / b2, where a represents the present EVOH composition layer and b represents the base resin layer. Furthermore, when R represents a recycled layer containing a mixture of the present EVOH composition and a thermoplastic resin other than the present EVOH composition, obtained by remelting and molding edges or defective products generated during the manufacturing process of the present multilayer structure, the layer structure can also be b / R / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R / a / R / b, or b / R / a / R / a / R / b. The total number of layers in the present multilayer structure is usually 2 to 15, and preferably 3 to 10. In the above layer structure, an adhesive resin layer containing an adhesive resin may be interposed between the respective layers, if necessary.

[0078] Known adhesive resins can be used, and may be selected appropriately depending on the type of thermoplastic resin used in the base resin layer "b." Representative examples include modified polyolefin polymers containing carboxy groups, which are obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin via addition reaction, graft reaction, or the like. Examples of modified polyolefin polymers containing carboxy groups include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. These may be used alone or in combination of two or more.

[0079] In the present multilayer structure, when adhesive resin layers are used between the present EVOH composition layer and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layers are located on both sides of the present EVOH composition layer.

[0080] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes, etc., within a range that does not impair the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, based on the total mass of the resin). These may be used alone or in combination of two or more kinds.

[0081] The lamination of the EVOH composition layer and the base resin layer (including the case where an adhesive resin layer is interposed) can be carried out by a known method. Examples include a method of melt-extrusion laminating a base resin onto a film, sheet, etc. of the EVOH composition, a method of melt-extrusion laminating the EVOH composition onto a base resin layer, a method of co-extruding the EVOH composition and the base resin, a method of dry-laminating the EVOH composition (layer) and the base resin (layer) using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound, and a method of applying a solution of the EVOH composition onto a base resin and then removing the solvent. Among these, from the viewpoints of cost and the environment, it is preferable to produce the EVOH composition by including a step of melt-molding the EVOH composition layer, and specifically, a co-extrusion method is preferred.

[0082] The multilayer structure may be subjected to a (heat) stretching treatment, if necessary. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming, or the like, whichever provides a higher stretch ratio. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

[0083] The stretched multilayer structure may be heat-set to provide dimensional stability. Heat-setting can be performed by known means, for example, by subjecting the stretched multilayer structure to heat treatment while maintaining tension, typically at 80 to 180°C, preferably 100 to 165°C, for typically 2 to 600 seconds.

[0084] When the stretched multilayer structure is to be used as a shrink film, the heat-shrinkability can be imparted to the multilayer structure by, for example, cooling and fixing the multilayer structure by applying cold air thereto, without carrying out the heat-setting process described above.

[0085] The thickness of the present multilayer structure (including a stretched structure), and the thicknesses of the present EVOH composition layer, base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generally determined depending on the layer configuration, type of base resin, type of adhesive resin, intended use, packaging form, required physical properties, etc., but the thickness of the present multilayer structure (including a stretched structure) is usually 10 to 5,000 μm, preferably 30 to 3,000 μm, and particularly preferably 50 to 2,000 μm. The thickness of the present EVOH composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, and particularly preferably 5 to 200 μm. The thickness of the base resin layer is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, and particularly preferably 20 to 1,000 μm. The thickness of the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

[0086] Furthermore, the thickness ratio of the present EVOH composition layer to the base resin layer in the present multilayer structure (present EVOH composition layer / base resin layer), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and particularly preferably 10 / 90 to 40 / 60. Furthermore, the thickness ratio of the present EVOH composition layer to the adhesive resin layer in the present multilayer structure (present EVOH composition layer / adhesive resin layer), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10.

[0087] The multilayer structure can also be molded to obtain cup- or tray-shaped molded articles. In this case, a drawing method is typically employed, specifically vacuum molding, pressure molding, vacuum-pressure molding, plug-assisted vacuum-pressure molding, etc. Furthermore, blow molding is employed to obtain tube- or bottle-shaped multilayer containers (laminate structures) from multilayer parisons (hollow tubular preforms before blowing). Specific examples include extrusion blow molding (double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cold parison biaxial stretch blow molding, injection-type cold parison biaxial stretch blow molding, injection-molding in-line biaxial stretch blow molding, etc.). The resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0088] Single-layer films formed from the present EVOH composition, and containers and lids (packaging containers) such as bags, cups, trays, tubes, and bottles formed from the present multilayer structure are useful as packaging containers for a variety of purposes, including general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0089] 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. Unless otherwise specified, "parts" and "%" below refer to mass standards. Prior to the examples, the following components were prepared.

[0090] (A) Component: EVOH EVOH (ethylene content 32 mol%, MFR (210 ° C, load 2160 g) 3.8 g / 10 min, density 1.19 g / cm 3 ) (B) component: a copolymer containing an ethylene structural unit and a structural unit represented by the formula (1); (B1 component): an ethylene-vinyl carboxylate copolymer and / or an ethylene-acrylic acid ester copolymer; B1-1: EVA (manufactured by Tosoh Corporation, Ultrathene 3B53A, MFR (190°C, load 2160 g) 5.7 g / 10 min, density 0.952 g / cm 3 B1-2: EVA (manufactured by Mitsui Dow Polychemicals, Evaflex EV170, MFR (190 ° C, load 2160 g) 1 g / 10 min, density 0.960 g / cm 3 B1-3: EVA (manufactured by Mitsui Dow Polychemicals, Evaflex V5961, MFR (190 ° C, load 2160 g) 1.7 g / 10 min, density 0.930 g / cm 3 B1-4: EEA (manufactured by Japan Polyethylene Corporation, Rexpearl EEA A4200, MFR (190 ° C, load 2160 g) 5 g / 10 min, density 0.934 g / cm 3 (B2 component): at least one copolymer selected from the group consisting of ethylene-vinyl carboxylate copolymers having a polar group, ethylene-acrylic acid ester copolymers having a polar group, ethylene-vinyl carboxylate-maleic anhydride copolymers, and ethylene-acrylic acid ester-acrylic acid ester-maleic anhydride copolymers. B2-1: maleic anhydride-modified EVA (MFR (190°C, load 2160 g) 16 g / 10 min, density 0.95 g / cm 3 B2-2: Maleic anhydride modified EVA (MFR (190 ° C, load 2160 g) 2 g / 10 min, density 0.92 g / cm 3B2-3: Ethylene-methyl acrylate-maleic anhydride copolymer (EMA) (manufactured by Japan Polyethylene Co., Ltd., Rexpearl ET ET230X, MFR (190 ° C, load 2160 g) 8.0 g / 10 min, density 0.943 g / cm 3 ) (Component C): Titanium compound Titanium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., purity 99.0%+)

[0091] Example 1 A mixture was obtained by dry-blending 80 parts of (A), 15 parts of (B1-1), 5 parts of (B2-1), and (C) so that the metal content was 0.1 ppm by mass per mass of the entire composition [the sum of (A) + (B1-1) + (B2-1)]. The mixture was then fed to a twin-screw extruder (20 mmφ) equipped with a two-hole die and extruded under the following extrusion conditions. The extruded strand was cooled and solidified in a water bath. Air was then blown onto the solidified strand to remove water droplets from the surface of the strand, and the strand was then cut to obtain pellets of the EVOH composition. [Extrusion conditions] Extruder set temperatures (°C): C1 / C2 / C3 / C4 / C5 / C6 = 150 / 200 / 210 / 210 / 210 / 210 (Here, C1 to C6 indicate the heating sections of the extruder. Specifically, C indicates the barrel section of the extruder, and C1 to C6 are listed from the section closest to the hopper.)

[0092] Examples 2 to 7, Comparative Examples 1 to 3 Pellets of EVOH compositions were obtained in the same manner as in Example 1, except that the materials contained in the mixture were changed to those shown in Table 1 below.

[0093] The resulting pellets of the EVOH composition were evaluated for "thermal stability" and "coloration suppression" using the following indices.

[0094] [Thermal Stability] To evaluate the stability during heating, the mass was measured before and after heating as follows, and the residual rate (%) was calculated. That is, 5 mg of the obtained pellets were measured using a thermogravimetric analyzer (Perkin Elmer, Pyris 1 TGA) under conditions of a nitrogen atmosphere, an airflow rate of 20 mL / min, a temperature of 230°C, and a time of 63 minutes. The masses before and after heating were then substituted into the following formula to calculate the residual rate. The obtained values ​​are also shown in Table 1 below. Mass residual rate (%) = mass after heating / mass before heating × 100. The higher the mass residual rate, the better the thermal stability. Note that in this evaluation, the difference after 63 minutes of heating was measured, but in actual production, the product is subjected to a longer thermal history. Therefore, even if the numerical difference in this evaluation appears small, it actually results in a large difference in effect.

[0095] [Coloration Suppression] To evaluate the change in coloration before and after heating, the (YI value) before and after heating was measured as described below, and the difference (YI value after heating - YI value before heating) was calculated. That is, first, the obtained pellets were crushed into 1 to 5 mm squares, and the crushed material was filled into a cylinder with an inner diameter of 32 mm and a height of 30 mm. After being rubbed, the YI value was measured using a spectrophotometer SE6000 (manufactured by Nippon Denshoku Industries Co., Ltd.) (YI value before heating). Next, the crushed material was heat-treated in an oven in an air atmosphere at 150°C for 5 hours, and the YI value of the crushed material after heating was also measured in the same manner (YI value after heating). The obtained values ​​are also shown in Table 1 below. It can be said that the smaller the difference in YI value before and after heating, the more the coloration due to heating is suppressed.

[0096]

[0097] Examples 1 to 3, which contain a specific amount of titanium compound (C), have the same mass residual ratio as Comparative Example 1, but have a smaller YI value after heating, indicating that heat-induced discoloration is suppressed. Example 7 also has the same mass residual ratio as Comparative Example 3, but also shows that heat-induced discoloration is suppressed. Comparative Example 2, which contains a titanium compound (C) in an amount exceeding the amount specified in the present invention, has a lower mass residual ratio than Examples 1 to 3, indicating poorer thermal stability. Thus, the present EVOH composition can reduce heat-induced discoloration while maintaining thermal stability.

[0098] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0099] The present composition has excellent thermal stability and is inhibited from discoloring due to heating. Therefore, molded articles made from the composition and multilayer structures having a layer containing the composition are useful as materials for various packaging containers.

Claims

1. A composition comprising an ethylene-vinyl alcohol copolymer (A), a copolymer (B) containing an ethylene structural unit and a structural unit represented by the following formula (1), and a titanium compound (C), wherein the content of the titanium compound (C) in the composition is 0.001 ppm by mass or more and less than 10 ppm by mass in terms of metal:

2. R represented by the above formula (1) Ａ The composition according to claim 1, wherein is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 4 carbon atoms.

3. The composition according to claim 1, wherein the copolymer (B) comprises an ethylene-vinyl carboxylate copolymer and / or an ethylene-acrylic acid ester copolymer (B1).

4. The composition according to claim 1, wherein the copolymer (B) comprises: (B1) an ethylene-vinyl carboxylate copolymer and / or an ethylene-acrylic ester copolymer; and (B2) at least one copolymer selected from the group consisting of an ethylene-vinyl carboxylate copolymer having a polar group, an ethylene-acrylic ester copolymer having a polar group, an ethylene-vinyl carboxylate-maleic anhydride copolymer, and an ethylene-acrylic ester-maleic anhydride copolymer.

5. The composition according to claim 4, wherein the polar group in the ethylene-vinyl carboxylate copolymer having a polar group is a carboxy group or a carbonyloxycarbonyl group.

6. The composition according to claim 4, wherein the copolymer (B) is an ethylene-vinyl carboxylate copolymer having a polar group and / or an ethylene-acrylic acid ester copolymer having a polar group, and at least one of the polar groups is a carboxy group.

7. The composition of claim 5, wherein the carbonyloxycarbonyl in said carbonyloxycarbonyl group is maleic anhydride.

8. The composition according to claim 1, wherein the content of the titanium compound (C) in the composition is 0.001 ppm by mass or more and 5 ppm by mass or less.

9. The composition according to claim 1, wherein the mass ratio (A / B) of the ethylene-vinyl alcohol copolymer (A) to the copolymer (B) is 70 / 30 to 99 / 1.

10. The composition according to claim 1, wherein the mass ratio (A / B) of the ethylene-vinyl alcohol copolymer (A) to the copolymer (B) is 70 / 30 to 85 / 15.

11. The composition according to claim 4, wherein the mass ratio (B2 / B1) of said copolymer (B2) to said copolymer (B1) is 0.01 to 10.

12. The composition according to claim 4, wherein a mass ratio of the ethylene-vinyl alcohol copolymer (A) to the total mass of the copolymer (B1) and the copolymer (B2), [A / (B1+B2)], is 50 / 50 to 99 / 1.

13. A composition for recycling, wherein the composition according to any one of claims 1 to 12 is for recycling.

14. A regrind layer comprising the composition of any one of claims 1 to 12.

15. A multilayer structure having a layer comprising the composition according to any one of claims 1 to 12.

16. The multilayer structure according to claim 15, further comprising an adhesive resin layer.

17. A molded article obtained by molding the multilayer structure according to claim 15.

18. A packaging material container formed from the multilayer structure according to claim 15.

19. A method for producing the composition according to claim 1, comprising the step of mixing the ethylene-vinyl alcohol copolymer (A), the copolymer (B), and the titanium compound (C).

20. A method for producing the composition according to claim 4, comprising the step of mixing the ethylene-vinyl alcohol copolymer (A), the copolymer (B1), the copolymer (B2), and the titanium compound (C).

21. A method for producing a multilayer structure, comprising the steps of obtaining a composition by the method for producing a composition according to claim 19 or 20, and forming a layer containing the composition obtained by said step as at least one layer of a multilayer structure.

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