Composition, material for melt processing, multi-layered structure, multi-layered container, and methods for producing composition and multi-layered structure

Abstract

The present invention provides a composition which has an improved thermal decomposition temperature during melt processing and which exhibits excellent thermal stability.　The composition contains an ethylene-vinyl alcohol copolymer (A) and a titanium compound (B). The ethylene-vinyl alcohol copolymer (A) contains at least two components, namely an ethylene-vinyl alcohol copolymer (A1) and an ethylene-vinyl alcohol copolymer (A2), which have different ethylene structural unit content values. In the ethylene-vinyl alcohol copolymer (A), the difference in ethylene structural unit content value between the ethylene-vinyl alcohol copolymer (A1) and the ethylene-vinyl alcohol copolymer (A2) is 4 mol% or more. The degree of saponification of the ethylene-vinyl alcohol copolymer (A2) is 90-99.7 mol%. The content of the titanium compound (B) is not less than 0.001×10-6 parts by mass and less than 5×10-6 parts by mass in terms of metal relative to 1 part by mass of the ethylene-vinyl alcohol copolymer (A2).

Description

Composition, melt-molding material, multilayer structure, multilayer container, and method for producing composition and multilayer structure

[0001] The present invention relates to a composition, a melt-molding material, a multilayer structure, a multilayer container, and a method for producing the composition and the multilayer structure.

[0002] Ethylene-vinyl alcohol copolymers (hereinafter, sometimes referred to as "EVOH resins") are excellent in transparency, gas barrier properties such as oxygen and other gases, aroma retention, solvent resistance, oil resistance, mechanical strength, and the like, and are formed into films, sheets, bottles, and the like, and are widely used as various packaging materials such as food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, and agricultural chemical packaging materials.

[0003] However, since EVOH resin has a relatively active hydroxyl group in the molecule, it is easily deteriorated by heat. EVOH resin with a low degree of saponification in particular has the characteristics of excellent stretchability and container moldability, but tends to have a further decrease in heat resistance due to reactions such as thermal decomposition of the vinyl ester monomer structural unit before saponification and elimination of acid. Therefore, problems such as discoloration and gelation occur during melt molding, and melt stability tends to decrease. Therefore, methods for obtaining compositions that are less likely to cause poor appearance during molding have been investigated.

[0004] For example, Patent Document 1 discloses a composition using EVOH resins with different ethylene contents and saponification degrees in combination, and discloses that the difference in ethylene content between the two types of EVOH resins used in combination is 4 mol % or more, the difference in saponification degrees is 3 mol % or more, and the difference in solubility parameters is a predetermined value or more, and the composition is used as an intermediate layer. The composition is laminated with a polyethylene layer or the like and subjected to vacuum and pressure molding to produce a molded product that has excellent transparency and appearance, is free from cracks and thickness deviations, and also has excellent gas barrier properties.

[0005] Furthermore, Patent Document 2 discloses that by incorporating 0.005 to 0.1 parts by mass of an organic titanate per 100 parts by mass of EVOH resin, thickness variations in the transverse (TD) direction during film formation by inflation molding or the like are suppressed, and molded products such as films and sheets with uniform thickness can be obtained.

[0006] Furthermore, Patent Document 3 discloses that by incorporating a specific amount of unsaturated aldehyde into an EVOH resin, oxidative degradation during melt molding can be suppressed, and discoloration can be suppressed.

[0007] Japanese Patent Application Laid-Open No. 63-230757 Japanese Patent Application Laid-Open No. 2004-244451 International Publication No. 2013 / 146961

[0008] However, the techniques disclosed in Patent Documents 1 and 2 have insufficient thermal stability during melt molding, etc., of the compositions, and there is room for improvement. Furthermore, in the technique disclosed in Patent Document 3, since even a small amount of aldehyde compound can cause a foul odor, there is a concern that the aldehyde compound will volatilize, particularly during melt molding at high temperatures, and this will worsen the working environment. Therefore, there is a demand for a composition that does not use such volatile compounds and has excellent thermal stability during the melt molding process.

[0009] Under these circumstances, the present invention provides a composition having excellent thermal stability by improving the thermal decomposition temperature of the composition during melt molding.

[0010] However, the present inventors have found that by including two or more types of EVOH resins having different contents of ethylene structural units and blending a specific trace amount of a titanium compound with a specific EVOH resin contained in the EVOH resins, the thermal decomposition temperature of the composition during melt molding can be improved, and a composition with excellent thermal stability can be obtained.

[0011] That is, the present invention has the following aspects: [1] A composition containing an EVOH resin (A) and a titanium compound (B), wherein the EVOH resin (A) contains at least two kinds of EVOH resins, namely, an EVOH resin (A1) and an EVOH resin (A2), which differ in the content of ethylene structural units, the difference in the content of ethylene structural units between the EVOH resin (A1) and the EVOH resin (A2) in the EVOH resin (A) is 4 mol % or more, the saponification degree of the EVOH resin (A2) is 90 to 99.7 mol %, and the content of the titanium compound (B) calculated as metal is 0.001 × 10 per part by mass of the EVOH resin (A2). -6 Mass part or more 5×10 -6a composition in which the EVOH resin (A2) contains less than parts by mass. [2] The composition according to [1], wherein the content of ethylene structural units in the EVOH resin (A2) is greater than the content of ethylene structural units in the EVOH resin (A1). [3] The composition according to [1] or [2], wherein the saponification degree of the EVOH resin (A2) is lower than the saponification degree of the EVOH resin (A1). [4] The composition according to any of [1] to [3], wherein the difference in the saponification degrees of the EVOH resin (A1) and the EVOH resin (A2) is 0.2 mol % or more. [5] The composition according to any of [1] to [4], wherein the mass content ratio (A1 / A2) of the EVOH resin (A1) to the EVOH resin (A2) is 95 / 5 to 50 / 50. [6] The composition according to any one of [1] to [5], wherein the ratio (Ti / VAc) [μmol / mol] of the metal-equivalent content of the titanium compound (B) to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) is 0.1 to 300. [7] A melt-molding material comprising the composition according to any one of [1] to [6]. [8] A multilayer structure having a layer containing the composition according to any one of [1] to [6]. [9] A multilayer container comprising the multilayer structure according to [8].

[10] The multilayer container according to [9], wherein the shape of the multilayer container is a cup or a tray.

[11] A method for producing the composition according to any one of [1] to [6], comprising the step of mixing two or more types of EVOH resins (A) having different contents of ethylene structural units with a titanium compound.

[12] A method for producing the multilayer structure according to [8], comprising the step of melt-molding a layer containing the composition.

[0012] The composition of the present invention has an improved thermal decomposition temperature during melt molding and is excellent in thermal stability.

[0013] 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.

[0014] In this specification, "x and / or y (x and y are any configuration)" means at least one of x and y, and can mean three things: 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 more 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 more than X" or "preferably less than Y." For numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. 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.

[0015] <Composition> A composition according to one embodiment of the present invention (hereinafter sometimes referred to as "the composition") comprises, as a main component, an EVOH resin (A) containing two or more types of EVOH resins differing in the content of ethylene structural units, and contains a specific trace amount of a titanium compound (B) relative to the specific EVOH resin. That is, the base resin of the composition is the EVOH resin (A), and the content of the EVOH resin (A) in the composition is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Each component will be described below.

[0016] [EVOH Resin (A)] The EVOH resin (A) used in this embodiment contains at least two types of EVOH resins, namely, EVOH resin (A1) and EVOH resin (A2), which differ in the content of ethylene structural units. The EVOH resin (A) is usually a water-insoluble thermoplastic resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer.

[0017] Vinyl acetate is typically used as the vinyl ester monomer because of its commercial availability and the efficiency of impurity removal during production. Examples of vinyl ester monomers other than vinyl acetate include 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. Typically, an aliphatic vinyl ester having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms, is used. These are typically used alone, but multiple types may be used simultaneously as necessary.

[0018] The copolymerization of ethylene and vinyl ester monomers can be carried out using any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, 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. The EVOH resin produced in this manner is primarily composed of ethylene-derived structural units and vinyl alcohol structural units, with a small amount of vinyl ester structural units remaining unsaponified.

[0019] The EVOH resin (A) may further contain structural units derived from the following comonomers (for example, 10 mol % or less of the EVOH resin) within the range that does not impair the effects of the present invention.Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxy group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-pentene-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esters and acylation products; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyl hydroxyalkylvinylidene diacetates such as methyloxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or their salts or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its acid salts or quaternary salts thereof acrylamides such as methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salts, methacrylamidepropyldimethylamine or its acid salts or its quaternary salts; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers in which the alkyl group has 1 to 18 carbon atoms, hydrochloric acid vinyl ethers such as alkoxyalkyl vinyl ether and alkoxyalkyl vinyl ether; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These may be used alone or in combination of two or more.

[0020] Among these, hydroxy group-containing α-olefins are preferred, and 3-butene-1,2-diol and 5-hexene-1,2-diol are particularly preferred. When the hydroxy group-containing α-olefins are copolymerized, the resulting EVOH resin has primary hydroxyl groups in the side chains. Such EVOH resins having primary hydroxyl groups in the side chains, particularly EVOH resins having a 1,2-diol structure in the side chains, are preferred in that they exhibit good secondary moldability while maintaining gas barrier properties.

[0021] When the EVOH resin (A) has a primary hydroxyl group in a side chain, the content of the structural unit derived from the monomer having the primary hydroxyl group is usually 0.1 to 20 mol %, preferably 0.5 to 15 mol %, particularly preferably 1 to 10 mol %, of the EVOH resin.

[0022] Furthermore, as the EVOH resin (A), EVOH resins that have been "post-modified" by esterification, urethanization, acetalization, cyanoethylation, oxyalkylenation, or the like can also be used.

[0023] When the post-modified EVOH resin is used, the modification rate is usually 10 mol % or less, and preferably 4 mol % or less. When the modification rate of the EVOH resin is within the above range, the resin is less susceptible to thermal degradation and tends to have improved long-run properties.

[0024] The EVOH resin (A) used in the present composition does not include modified EVOH resins having a structure represented by the following chemical formula (1).

[0025] (In chemical formula (1), X represents an organic chain having a heteroatom, and n represents a positive integer.)

[0026] As described above, the EVOH resin (A) contains at least two types of EVOH resins, EVOH resin (A1) and EVOH resin (A2), which differ in the content of ethylene structural units. The number of types of EVOH resins differing in the content of ethylene structural units is usually 2 to 4, preferably 2 to 3, and particularly preferably 2. When the number of types is within the above range, productivity and economy tend to be excellent.

[0027] The number of different EVOH resins with different contents of ethylene structural units contained in the composition can be determined from the number of peaks measured using a differential scanning calorimeter (DSC) as described below.

[0028] From the viewpoints of gas barrier properties and container moldability, it is preferable that the content of ethylene structural units in the EVOH resin (A2) is greater than the content of ethylene structural units in the EVOH resin (A1).

[0029] From the viewpoints of gas barrier property and moldability into a container, it is preferable that the EVOH resin (A1) is an EVOH resin having the smallest content of ethylene structural units among the EVOH resins (A), and that the EVOH resin (A2) is an EVOH resin having the largest content of ethylene structural units among the EVOH resins (A).

[0030] In the EVOH resin (A), the difference in the content of ethylene structural units between the EVOH resin (A1) and the EVOH resin (A2) is 4 mol% or more, preferably 5 to 30 mol%, more preferably 6 to 25 mol%, and even more preferably 7 to 20 mol%. When the difference in the content of ethylene structural units is equal to or greater than the lower limit, thickness deviation and cracks tend to be less likely to occur during molding of the multilayer container, while when it is equal to or less than the upper limit, gas barrier properties tend to be improved and the appearance tends to be excellent.

[0031] The difference in the content of the ethylene structural unit between the two or more types of EVOH resins contained in the EVOH resin (A) may be, for example, 1 It can be determined by using H-NMR.

[0032] The content of ethylene structural units in the EVOH resin (A) is usually 20 to 60 mol %, preferably 22 to 50 mol %, and particularly preferably 25 to 45 mol %. When the content is equal to or greater than the lower limit, in gas barrier applications, the gas barrier properties under high humidity and melt moldability tend to be improved, whereas when the content is equal to or less than the upper limit, the gas barrier properties tend to be improved.

[0033] The EVOH resin (A1) has an ethylene structural unit content of usually 20 to 50 mol%, preferably 22 to 45 mol%, more preferably 24 to 40 mol%, and even more preferably 27 to 35 mol%. When the ethylene structural unit content is equal to or greater than the lower limit, secondary processability and flexibility tend to be improved, while when it is equal to or less than the upper limit, gas barrier properties tend to be improved.

[0034] The content of ethylene structural units in the EVOH resin (A2) is usually 30 to 60 mol%, preferably 32 to 55 mol%, more preferably 35 to 51 mol%, and even more preferably 38 to 44 mol%. When the content of ethylene structural units is equal to or greater than the lower limit, secondary processability and flexibility tend to be improved, while when it is equal to or less than the upper limit, gas barrier properties tend to be improved.

[0035] In this specification, the content of ethylene structural units in the EVOH resin or composition is 1 The values ​​are measured using H-NMR.

[0036] The EVOH resin (A) contains at least two types of EVOH resins, namely, EVOH resin (A1) and EVOH resin (A2), which differ in the content of ethylene structural units. Furthermore, the EVOH resin (A1) and the EVOH resin (A2) preferably have different degrees of saponification, and the degree of saponification of the EVOH resin (A2) is more preferably lower than the degree of saponification of the EVOH resin (A1).

[0037] The saponification degree of the EVOH resin (A) is usually 90 to 100 mol%, preferably 95 to 100 mol%, and particularly preferably 97 to 100 mol%. When the saponification degree is equal to or higher than the lower limit, the gas barrier property, thermal stability, moisture resistance, etc. tend to be improved.

[0038] The difference in saponification degree between the EVOH resin (A1) and the EVOH resin (A2) in the EVOH resin (A) is usually 0.2 mol % or more, preferably 0.3 mol % or more, more preferably 0.4 mol % or more, and even more preferably 0.5 mol % or more. When the difference in saponification degree is equal to or greater than the lower limit, thickness deviation and cracks tend to be less likely to occur during molding of the multilayer container, while when the difference is equal to or less than the upper limit, gas barrier properties tend to be improved.

[0039] The saponification degree of the EVOH resin (A1) is usually 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 99 to 100 mol%, and particularly preferably 99.5 to 100 mol%. When the saponification degree is equal to or higher than the lower limit, the gas barrier property, thermal stability, moisture resistance, etc. tend to be improved.

[0040] The saponification degree of the EVOH resin (A2) is usually 90 to 99.7 mol%, preferably 93 to 99.5 mol%, and more preferably 95 to 99 mol%. When the saponification degree is equal to or higher than the lower limit, the gas barrier property, thermal stability, moisture resistance, etc. tend to be improved, while when it is equal to or lower than the upper limit, the secondary processability and flexibility tend to be improved.

[0041] In this specification, the content of ethylene structural units and the degree of saponification are calculated by the following measurement method. [Method for measuring the content of ethylene structural units and the degree of saponification] 50 mg of EVOH resin or composition is weighed into a vial, 1 mL of dimethyl sulfoxide-d6 (DMSO-d6) is added, and the resin or composition is dissolved by heating and stirring at 50°C. The resin or composition is then dissolved under the following conditions. 1H-NMR measurement was carried out. (Measurement conditions) - Device name: Thermal conductivity nuclear magnetic resonance device "AVANCE III HD 400" manufactured by Bruker - Observation frequency: 400 MHz - Solvent: DMSO-d6 (2.5 ppm) - Polymer concentration: 5 w / v% - Measurement temperature: 50°C - Number of accumulations: 16 (Analysis method) From the measured spectrum, the integral value of the signal with a chemical shift of 4.0-3.3 ppm (I1), the integral value of the signal with a chemical shift of 2.0 ppm (I2), the integral value of the signal with a chemical shift of 1.9-1.0 ppm (I3), and the integral value of the signal with a chemical shift of 1.0-0.7 ppm (I4) were determined. Here, the chemical shift signal between 4.0 and 3.3 ppm is mainly due to methine hydrogen adjacent to the hydroxy group, the chemical shift signal between 2.0 ppm is due to methyl hydrogen in unsaponified vinyl acetate units, the chemical shift signal between 1.9 and 1.0 ppm is due to methylene hydrogen in the main chain, and the chemical shift signal between 1.0 and 0.7 ppm is due to methyl hydrogen at the end of the ethylene unit. From these integral values, the content of ethylene structural units and the degree of saponification are calculated using the following formulas. [Ethylene structural unit content formula] (3 x I3 - 6 x I1 - 2 x I2 + 2 x I4) / (3 x I3 + 6 x I1 + 2 x I2 + 2 x I4) x 100 [Saponification degree formula] (3 x I1) / {(3 x I1) + I2} x 100

[0042] The melt flow rate (MFR) of the EVOH resin (A) (210°C, load: 2160 g) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and particularly preferably 2 to 35 g / 10 min. When the MFR is equal to or lower than the upper limit, film-forming properties tend to be stable, whereas when the MFR is equal to or higher than the lower limit, the viscosity does not become too high, and melt extrusion tends to be easy.

[0043] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (A1) is usually 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and particularly preferably 3 to 10 g / 10 min. When the MFR is equal to or lower than the upper limit, the mechanical strength of the molded product tends to be improved, while when the MFR is equal to or lower than the lower limit, the extrusion processability tends to be improved.

[0044] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (A2) is usually 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and particularly preferably 3 to 30 g / 10 min. If the MFR is equal to or lower than the upper limit, the mechanical strength of the molded product tends to be improved, whereas if the MFR is equal to or higher than the lower limit, the extrusion processability tends to be improved.

[0045] In the combination of EVOH resin (A1) and EVOH resin (A2), the difference in MFR (210°C, load 2160 g) (ΔMFR) is preferably 5 g / 10 min or less, more preferably 1.5 g / 10 min or less, so that the flow properties of the resins during melt molding are similar. The molecular weights of the respective EVOH resins are preferably adjusted so that the difference in MFR (ΔMFR) is 5 g / 10 min or less, more preferably 1.5 g / 10 min or less. In this specification, MFR was determined by measuring the flow rate of a sample passing through an orifice with a length of 8 mm and a hole diameter of 2.095 mm under conditions of a temperature of 210°C and a load of 2160 g, using a semi-automatic melt flow rate tester (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0046] The mass content ratio (A1 / A2) of the EVOH resin (A1) to the EVOH resin (A2) is usually 95 / 5 to 50 / 50, preferably 90 / 10 to 55 / 45, more preferably 88 / 12 to 60 / 40, and particularly preferably 85 / 15 to 70 / 30. When the content of EVOH resin (A1) is equal to or greater than the lower limit, the gas barrier properties tend to be excellent, and when it is equal to or less than the upper limit, thickness deviation and cracks tend to be less likely to occur during molding of the multilayer container. Such a content ratio is 1 The EVOH resin (A1) and the EVOH resin (A2) are isolated by a method such as extraction with a good solvent for each of them. 1 By measuring H-NMR, the contents of ethylene structural units in the EVOH resin (A1) and the EVOH resin (A2) are calculated. 1The content of the ethylene structural unit obtained by H-NMR measurement is a weighted average of the contents of the EVOH resin (A1) and the EVOH resin (A2). Therefore, the mass content ratio (A1 / A2) can be calculated using the measurement results of the contents of the ethylene structural unit of the EVOH resin (A1) and the EVOH resin (A2).

[0047] [Titanium Compound (B)] Examples of the titanium compound (B) include inorganic titanium compounds and organic titanium compounds. The titanium compounds may be used alone or in combination of two or more. Among these, inorganic titanium compounds are preferred.

[0048] Examples of the inorganic titanium compound include titanium oxide, titanium hydroxide, titanium chloride, and inorganic salts of titanium.

[0049] Examples of the titanium oxides include titanium(II) oxide, titanium(III) oxide, titanium(IV) oxide, and titanium zincate. Examples of the titanium hydroxides include titanium(II) hydroxide and titanium(II) hydroxide. Examples of the titanium chlorides include titanium(II) chloride and titanium(II) chloride. Examples of the titanium inorganic salts are those other than the titanium chlorides, such as titanium phosphate and titanium sulfate. Among these, titanium oxides are preferred, titanium(IV) oxide is more preferred, and rutile-type titanium(IV) oxide is particularly preferred.

[0050] Examples of the organic titanium compounds include titanium carboxylates such as titanium acetate, titanium butyrate, and titanium stearate.

[0051] The titanium compound (B) may exist in the 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.

[0052] The average particle size of the titanium compound (B) 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 is within the above range, the coloration suppression effect tends to be excellent.

[0053] The content of the titanium compound (B) in terms of metal is 0.001 × 10 per part by mass of the EVOH resin (A2). -6 Mass part or more 5×10 -6 parts by mass, preferably less than 0.005×10 -6 ~4 x 10 -6 parts by mass, more preferably 0.01 x 10 -6 ~3 x 10 -6 parts by mass, more preferably 0.05 x 10 -6 ~2 x 10 -6 The titanium compound content is expressed in parts by mass. When the titanium compound content is equal to or less than the upper limit, thermal decomposition of the EVOH resin tends to be less likely to occur, whereas when the titanium compound content is equal to or more than the lower limit, the effect of suppressing thermal degradation tends to be improved. The metal-equivalent content of the titanium compound (C) is the content of elemental titanium.

[0054] The content of the titanium compound (B) in terms of metal can be determined by weighing out the 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).

[0055] The ratio (Ti / VAc) [μmol / mol] of the content of the titanium compound (B) converted into metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) is usually 0.1 to 300, preferably 0.5 to 200, and more preferably 1 to 150. When the ratio of the content of the titanium compound (B) converted into metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) is within the above range, the EVOH resin tends to have excellent thermal stability.

[0056] It is generally believed that EVOH resins undergo thermal degradation due to the elimination of vinyl ester structural units caused by heat, resulting in the formation of double bonds in the main chain of the EVOH resin molecule. In the present composition, it is believed that the interaction between the vinyl ester structural units of the EVOH resin and the titanium of the titanium compound inhibits the elimination of the vinyl ester structural units of the EVOH resin, thereby improving thermal stability.

[0057] [Other Thermoplastic Resins] The composition may contain thermoplastic resins other than EVOH resin within a range that does not impair the effects of the present invention (for example, typically 30% by mass or less, preferably 20% by mass or less, and particularly preferably 10% by mass or less of the composition). Examples of other thermoplastic resins that may be used include known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, and chlorinated polypropylene. These may be used alone or in combination of two or more.

[0058] [Other Compounding Agents] The composition may also contain compounding agents that are generally compounded with EVOH resins, within the range that does not impair the effects of the present invention (for example, 5% by mass or less). Examples of such compounding agents include inorganic double salts (for example, hydrotalcite, etc.), plasticizers (for example, aliphatic polyhydric alcohols such as ethylene glycol, glycerin, and hexanediol), oxygen absorbers [for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, its fatty acid esters and metal salts, etc.; gallic acid; polyhydric phenols such as hydroxyl group-containing phenolaldehyde resins; terpene compounds; blends of tertiary hydrogen-containing resins and transition metals (for example, a combination of polypropylene and cobalt); and carbon-carbon unsaturated bond-containing resins and inorganic oxygen absorbers [for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; Polymeric oxygen absorbers such as blends with transition metals (e.g., a combination of polybutadiene and cobalt), photooxidatively degradable resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinyl anthraquinone), and combinations thereof to which photoinitiators (e.g., benzophenone) or antioxidants or deodorizers (e.g., activated carbon) other than those mentioned above may be added, as well as heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (excluding those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc. These compounds may be used alone or in combination of two or more.

[0059] [Method for Producing Composition] The present composition can be produced, for example, by mixing the EVOH resin (A) and the titanium compound (B) by a known method such as a dry blending method, a melt mixing method, a solution mixing method, an impregnation method, etc. Among these, it is preferable to produce the composition by a method including a step of melt mixing the composition raw materials containing the EVOH resin (A) and the titanium compound (B). Furthermore, these production methods can be used in any combination.

[0060] The dry blending method may be, for example, (i) a method in which a pellet-shaped EVOH resin (A) and a titanium compound (B) 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 EVOH resin (A) is dry-blended with a titanium compound (B) and the resulting dry blend is melt-kneaded, and (iii) a method in which a titanium compound (B) is added to a molten EVOH resin (A) and the resulting mixture is melt-kneaded.

[0062] Examples of the solution mixing method include (iv) a method in which a solution is prepared using a commercially available EVOH resin (A), a titanium compound (B) 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 the EVOH resin (A), a titanium compound (B) is added to a solution of an ethylene-vinyl ester copolymer before saponification or a homogeneous solution of the EVOH resin (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 pellets of EVOH resin (A) are contacted with an aqueous solution containing a titanium compound (B) to incorporate the titanium compound (B) into the EVOH resin (A), followed by drying. The aqueous solution containing the titanium compound (B) may be an aqueous solution of the titanium compound (B) or a solution in which titanium ions have been eluted from the titanium compound (B) by immersing the titanium compound (B) in water containing various chemicals. In the impregnation method, the content of the titanium compound (B) (in terms of metal) can be controlled by the concentration of the titanium compound (B) in the aqueous solution in which the EVOH resin (A) is immersed, the immersion temperature, the 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 with a more pronounced effect of the present invention can be obtained. 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 shape of the present composition obtained by each of the above-mentioned production methods may be any shape, but is preferably 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 pelletized EVOH resin used in each of the above-mentioned production methods are also preferably similar.

[0067] The water content of the present 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.

[0068] The moisture content of the composition is measured and calculated by the following method: The mass (W1) of the 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: [Formula] Moisture content (mass%) = [(W1 - W2) / W1] x 100

[0069] When the 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 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 composition is usually 5% by mass or less, preferably 1% by mass or less. The lower limit is usually 0% by mass.

[0070] The composition thus obtained has excellent thermal stability, and the temperature (°C) at which the composition loses 5% of its mass is usually 345.0°C or higher, preferably 346.0°C or higher, and more preferably 347.0°C or higher. The upper limit of the temperature (°C) at which the composition loses 5% of its mass is preferably as high as possible, but is usually 400°C.

[0071] The composition thus obtained is prepared into various forms, such as pellets, powder, or liquid, and is provided as a molding material for various molded products. In particular, in the present invention, when it is provided as a material for melt molding, the effects of the present invention tend to be more efficiently obtained, which is preferable. Note that the present composition also includes resin compositions obtained by mixing resins other than the EVOH resin used in the present composition.

[0072] Examples of the molded article include a monolayer film molded from the present composition, as well as a multilayer structure having a layer made of the present composition.

[0073] <Multilayer structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure") includes a layer made of the present composition. The layer made of the present composition (hereinafter simply referred to as "the composition layer") can be laminated with another substrate (hereinafter the resin used in the substrate may be abbreviated as "substrate resin") containing a thermoplastic resin other than the present composition as a main component, to impart additional strength, protect the present composition layer from the effects of moisture, etc., or impart other functions.

[0074] 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 polyolefin-based resins 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.

[0075] 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.

[0076] 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 denotes the composition layer and b denotes the base resin layer. Furthermore, when R denotes a recycled layer containing a mixture of the present composition and a thermoplastic resin other than the present 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 typically 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.

[0077] 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.

[0078] In the present multilayer structure, when an adhesive resin layer is used between the present composition layer and the base resin layer, since the adhesive resin layers are located on both sides of the present composition layer, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0079] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (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.

[0080] The lamination of the present composition layer and the above-mentioned substrate resin layer (including the case where an adhesive resin layer is interposed) can be carried out by a known method.For example, a method of melt-extrusion laminating a substrate resin onto a film, sheet, etc. of the present composition, a method of melt-extrusion laminating the present composition onto a substrate resin layer, a method of co-extruding the present composition and the substrate resin, a method of dry-laminating the present composition (layer) and the substrate resin (layer) using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, a polyurethane compound, etc., a method of applying a solution of the present composition onto a substrate resin and then removing the solvent, etc.Among these, in consideration of cost and environmental aspects, it is preferable to produce the present composition by providing a step of melt-molding the present composition layer, and specifically, a co-extrusion method is preferable.

[0081] 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.

[0082] 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.

[0083] When the stretched multilayer structure is to be used as a shrink film, the heat-shrinkability can be imparted by, for example, applying cold air to the stretched multilayer structure to cool and fix it, without carrying out the heat-setting process described above.

[0084] The thickness of the present multilayer structure (including a stretched structure), as well as the thickness of the present 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 present composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, and particularly preferably 5 to 200 μm; 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; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

[0085] Furthermore, the thickness ratio of the present composition layer to the base resin layer in the present multilayer structure (present 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 composition layer to the adhesive resin layer in the present multilayer structure (present 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.

[0086] The multilayer structure can also be used to produce cup- or tray-shaped multilayer containers. In this case, a drawing method is typically used, specifically vacuum forming, pressure forming, vacuum-pressure forming, plug-assisted vacuum-pressure forming, etc. Furthermore, blow molding is used to produce tube- or bottle-shaped multilayer containers (laminate structure) from a multilayer parison (a hollow tubular preform before blowing). Specific examples include extrusion blow molding (two-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.

[0087] Single-layer films formed from the present composition, bags made from the present multilayer structure, and containers and lids made from cups, trays, tubes, bottles, etc. are useful as packaging materials and containers for a variety of items, 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, pharmaceuticals, etc.

[0088] 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.

[0089] Example 1 Pellets of an EVOH resin (A1) having an ethylene structural unit content of 29 mol%, a saponification degree of 99.8 mol%, and an MFR of 3.9 g / 10 min (210°C, load 2160 g) were used. Pellets of an EVOH resin (A2) having an ethylene structural unit content of 38 mol%, a saponification degree of 98.5 mol%, and an MFR of 3.5 g / 10 min (210°C, load 2160 g) were used. Furthermore, rutile-type titanium (IV) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) having an average particle size of 5 μm or less was used as the titanium compound (B). The EVOH resin (A1) and the EVOH resin (A2) were blended at a mass content ratio of A1 / A2 = 80 / 20. The titanium oxide was added in an amount of 0.5 × 10 titanium dioxide per part of the EVOH resin (A2) in terms of metal. -6 The EVOH resin (A2) and the titanium oxide were dry-blended so that the titanium oxide content was 43.0 μmol / mol in terms of metal relative to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2). The mixture was fed into a twin-screw extruder (20 mmφ) equipped with a two-hole die and extruded under the following extrusion conditions. The extruded strands were cooled and solidified in a water bath. Air was then blown onto the solidified strands to remove water droplets from the strand surface, and the strands were then cut to obtain pellets of the composition. [Extrusion conditions] Extruder set temperatures (°C): C1 / C2 / C3 / C4 = 160 / 220 / 220 / 220

[0090] Example 2 Pellets of a composition were obtained in the same manner as in Example 1, except that, as the EVOH resin (A2), pellets of an EVOH resin having an ethylene structural unit content of 38 mol%, a saponification degree of 95.2 mol%, and an MFR of 3.2 g / 10 min (210°C, load: 2160 g) were used, and the content ratio of titanium oxide in terms of metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was 13.7 µmol / mol.

[0091] Example 3 Pellets of a composition were obtained in the same manner as in Example 1, except that, as the EVOH resin (A2), pellets of an EVOH resin having an ethylene structural unit content of 44 mol%, a saponification degree of 97.6 mol%, and an MFR of 3.6 g / 10 min (210°C, load: 2160 g) were used, and the content ratio of titanium oxide in terms of metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was 29.2 μmol / mol.

[0092] Example 4 In Example 1, the mass content ratio of the EVOH resin (A1) to the EVOH resin (A2) was set to A1 / A2 = 90 / 10, and the titanium oxide content in terms of metal was 1 × 10 per part of the EVOH resin (A2). -6 Pellets of a composition were obtained in the same manner as in Example 1, except that the amount of titanium oxide was changed to 100 parts, and the content ratio of titanium oxide in terms of metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was changed to 86.1 μmol / mol.

[0093] Example 5 In Example 1, the mass content ratio of the EVOH resin (A1) to the EVOH resin (A2) was changed to A1 / A2 = 70 / 30, and the titanium oxide content in terms of metal was 0.33 × 10 per part of the EVOH resin (A2). -6 Pellets were obtained in the same manner as in Example 1, except that the amount of titanium oxide was changed to 28.4 μmol / mol, and the ratio of the content of titanium oxide in terms of metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was changed to 28.4 μmol / mol.

[0094] Comparative Example 1 Pellets of a composition were obtained in the same manner as in Example 1, except that titanium oxide was not used.

[0095] Comparative Example 2 In Example 1, titanium oxide was used in an amount of 5×10 per part of EVOH resin (A2) in terms of metal content. -6 Pellets of a composition were obtained in the same manner as in Example 1, except that the amount of titanium oxide was changed to 430.3 parts, and the metal-equivalent content ratio of titanium oxide to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was changed to 430.3 μmol / mol.

[0096] Comparative Example 3 Pellets of a composition were obtained in the same manner as in Example 1, except that, as the EVOH resin (A2), pellets of an EVOH resin having an ethylene structural unit content of 38 mol%, a saponification degree of 99.8 mol%, and an MFR of 4.0 g / 10 min (210°C, load: 2160 g) were used, and the metal-equivalent content ratio of titanium oxide to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was 319.9 µmol / mol.

[0097] Comparative Example 4 In Example 4, titanium oxide was used in an amount of 10×10 per part of EVOH resin (A2) in terms of metal content. -6 Pellets of a composition were obtained in the same manner as in Example 4, except that the amount of titanium oxide was changed and the content ratio of titanium oxide in terms of metal to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was changed to 860.6 μmol / mol.

[0098] Comparative Example 5 In Comparative Example 3, titanium oxide was used in an amount of 5×10 per part of EVOH resin (A2) in terms of metal content. -6 Pellets of a composition were obtained in the same manner as in Example 3, except that the amount of titanium oxide was changed to 3,198.7 parts, and the metal-equivalent content ratio of titanium oxide to the vinyl ester structural units remaining unsaponified in the EVOH resin (A2) was changed to 3,198.7 μmol / mol.

[0099] The following thermal stability evaluation was carried out using the pellets of the compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 5. The results are shown in Table 1 below.

[0100] [Evaluation of Thermal Stability] Using 10 mg of pellets of the obtained composition, the temperature at which the mass had decreased to 95% of the mass before measurement (5% decrease temperature) was measured using a thermogravimetric analyzer (TGA-8000, manufactured by Shimadzu Corporation) in a nitriding atmosphere under conditions of an air flow rate of 20 mL / min, a heating rate of 10° C. / min, and a temperature range of 50 to 550° C. A higher temperature indicates better thermal stability.

[0101]

[0102] The results in Table 1 above show that the compositions of Examples 1 to 5, which contained a specific trace amount of titanium compound (B) relative to the EVOH resin (A2), had higher 5% reduction temperatures and therefore superior thermal stability than the composition of Comparative Example 1, which did not contain titanium compound (B), and the compositions of Comparative Examples 2, 4, and 5, which contained titanium compound (B) in amounts exceeding the specific range relative to the EVOH resin (A2). Furthermore, the compositions of Examples 1 to 5, in which the saponification degree of EVOH resin (A2) was within a specific range, had higher 5% reduction temperatures and therefore superior thermal stability than the composition of Comparative Example 3, in which the saponification degree of EVOH resin (A2) exceeded the range. Furthermore, the multilayer structures and multilayer containers comprising layers made of the compositions of Examples 1 to 5 also exhibited excellent thermal stability.

[0103] 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.

[0104] The present composition has an improved thermal decomposition temperature during melt molding and is excellent in thermal stability, and is therefore useful as a packaging material for a variety of foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, medical products, and the like.

Claims

1. A composition containing an ethylene-vinyl alcohol copolymer (A) and a titanium compound (B), wherein the ethylene-vinyl alcohol copolymer (A) contains at least two types of ethylene-vinyl alcohol copolymers, namely, an ethylene-vinyl alcohol copolymer (A1) and an ethylene-vinyl alcohol copolymer (A2), which differ in the content of ethylene structural units, the difference in the content of ethylene structural units between the ethylene-vinyl alcohol copolymer (A1) and the ethylene-vinyl alcohol copolymer (A2) in the ethylene-vinyl alcohol copolymer (A) is 4 mol % or more, the saponification degree of the ethylene-vinyl alcohol copolymer (A2) is 90 to 99.7 mol %, and the content of the titanium compound (B) calculated as metal is 0.001 x 10 per part by mass of the ethylene-vinyl alcohol copolymer (A2). -6 Mass part or more 5×10 -6 The composition, 2. The composition according to claim 1, wherein the content of ethylene structural units in the ethylene-vinyl alcohol copolymer (A2) is greater than the content of ethylene structural units in the ethylene-vinyl alcohol copolymer (A1).

3. The composition according to claim 1 or 2, wherein the saponification degree of the ethylene-vinyl alcohol copolymer (A2) is lower than the saponification degree of the ethylene-vinyl alcohol copolymer (A1).

4. The composition according to claim 1 or 2, wherein the difference in degree of saponification between the ethylene-vinyl alcohol copolymer (A1) and the ethylene-vinyl alcohol copolymer (A2) is 0.2 mol % or more.

5. The composition according to claim 1 or 2, wherein the mass content ratio (A1 / A2) of the ethylene-vinyl alcohol copolymer (A1) to the ethylene-vinyl alcohol copolymer (A2) is 95 / 5 to 50 / 50.

6. The composition according to claim 1 or 2, wherein the ratio (Ti / VAc) [μmol / mol] of the content of said titanium compound (B) in terms of metal to the vinyl ester structural units remaining unsaponified in said ethylene-vinyl alcohol copolymer (A2) is 0.1 to 300.

7. A melt-molding material comprising the composition according to claim 1 or 2.

8. A multi-layer structure having a layer comprising the composition according to claim 1 or 2.

9. A multilayer container comprising the multilayer structure according to claim 8.

10. The multi-layer container according to claim 9, wherein the shape of the multi-layer container is a cup or a tray.

11. A method for producing the composition according to claim 1 or 2, comprising the step of mixing two or more types of ethylene-vinyl alcohol copolymers (A) having different contents of ethylene structural units with a titanium compound.

12. A method for producing a multi-layer structure according to claim 8, comprising the step of melt forming a layer comprising said composition.

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