Resin composition and molded article using same

Abstract

Provided is a resin composition containing a modified ethylene-vinyl alcohol copolymer (A) and an ethylene-vinyl alcohol copolymer (B), wherein the modified ethylene-vinyl alcohol copolymer (A) includes structural units (Ia), (Ib), and (Ic) represented by the following formulas, the content (mol%) a, b, and c of the structural units (Ia), (Ib), and (Ic) satisfy formulas (1)-(3), the degree of saponification (DS) of a modified vinyl alcohol (A) represented by formula (4) is 90 mol% or more, the ethylene-vinyl alcohol copolymer (B) does not contain the structural unit (Ic), the ethylene unit content is 33-54 mol%, the degree of saponification is 80 mol% or more, and the mass ratio (A / B) of the modified ethylene-vinyl alcohol copolymer (A) to the ethylene-vinyl alcohol copolymer (B) is 30 / 70 to 95 / 5. By using such a resin composition, a film having high gas barrier properties and stretchability, and having high yield stress even after being stored under high humidity can be obtained. (1): 33≤a≤54 (2): 0.1≤c<3 (3): [100-(a+c)]×0.9≤b≤(100-(a+c)) (4): DS=[(total number of moles of hydrogen atoms from among X, Y and Z) / (total number of moles of X, Y and Z)]×100

Description

Resin composition and molded article using the same

[0001] The present invention relates to a resin composition containing a modified ethylene-vinyl alcohol copolymer containing a predetermined structural unit and an ethylene-vinyl alcohol copolymer not containing the structural unit, and to a molded article using the same.

[0002] Ethylene-vinyl alcohol copolymers (hereinafter sometimes abbreviated as EVOH) have excellent transparency, gas barrier properties, aroma retention, solvent resistance, oil resistance, and the like. Taking advantage of these properties, they are used in a wide range of applications, including packaging materials such as food packaging, pharmaceutical packaging, industrial chemical packaging, and agricultural chemical packaging; fuel containers, and the like. When producing such molded products, EVOH is often subjected to secondary processing after melt molding. For example, it is common to stretch a film containing an EVOH layer to improve mechanical strength or impart heat shrinkability, or to thermoform a sheet containing an EVOH layer to form a container shape. In addition, in recent years, there has been an increasing demand for stretching at a higher stretch ratio in order to further improve performance. For these reasons, there is a demand for resins that have improved secondary processability without impairing the gas barrier properties inherent to EVOH as much as possible.

[0003] Patent Documents 1 to 3 describe that a resin composition containing unmodified EVOH and modified EVOH copolymerized with 3,4-dihydroxy-1-butene units has excellent stretchability and gas barrier properties. Patent Document 4 describes that a resin composition containing unmodified EVOH and modified EVOH copolymerized with 2-methylene-1,3-propanediol units has excellent barrier properties, impact resistance, secondary processability, etc. However, when films obtained using these resin compositions are used as packaging materials for meat and the like and stored under high humidity conditions for a long period of time, the yield stress of the film decreases, making it difficult to open.

[0004] JP 2006-124668 A JP 2007-261074 A JP 2007-261075 A WO2015 / 115511 A

[0005] The present invention has been made to solve the above problems, and provides a resin composition that can give a film having high gas barrier properties and stretchability, and that has high yield stress even after storage under high humidity conditions, and also provides suitable uses of such a resin composition.

[0006] The present invention is as follows: [1] A resin composition containing modified EVOH (A) and EVOH (B), wherein the modified EVOH (A) contains structural units (Ia), (Ib), and (Ic) represented by the following formulae, and the contents (mol %) a, b, and c of the structural units (Ia), (Ib), and (Ic) satisfy the following formulae (1) to (3), the degree of saponification (DS) of the modified vinyl alcohol (A) represented by the following formula (4) is 90 mol % or more, and the EVOH (B) does not contain the structural unit (Ic), has an ethylene unit content of 33 to 54 mol %, and a saponification degree of 80 mol % or more, and the mass ratio (A / B) of the modified EVOH (A) to the EVOH (B) is 30 / 70 to 95 / 5. [In the formula, a, b, and c represent the content (mol %) of each structural unit relative to 100 mol % of the total of all structural units, and W represents a hydrogen atom, a methyl group, or R ２ -OY, and X, Y, and Z each independently represent a hydrogen atom, a formyl group, or an alkanoyl group having 2 to 10 carbon atoms. １ , R ２each independently represent a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms, and the alkylene group and the alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom. * represents a bonding site.] 33≦a≦54 (1) 0.1≦c<3 (2) [100-(a+c)]×0.9≦b≦[100-(a+c)] (3) DS=[(total number of moles of X, Y, and Z that are hydrogen atoms) / (total number of moles of X, Y, and Z)]×100 (4) [2] The resin composition according to [1], wherein the mass ratio (A / B) of the modified ethylene-vinyl alcohol copolymer (A) to the ethylene-vinyl alcohol copolymer (B) is 40 / 60 to 95 / 5. [3] The resin composition according to [1] or [2], wherein the content (mol %) a of the structural unit (Ia) is 35 mol % or more and 44 mol % or less. [4] The resin composition according to any one of [1] to [3], wherein the water absorption rate when immersed in water at 20°C for 2 hours is 6.5 mass % or less. [5] The resin composition according to any one of [1] to [4], wherein the content of components having a weight average molecular weight of 200 or more and less than 1,000 is 5 mass % or less. [6] A film or sheet having a layer made of the resin composition according to any one of [1] to [5]. [7] The film or sheet according to [6], further having a layer made of a thermoplastic resin. [8] The film or sheet according to [6] or [7], which is stretched to an area ratio of 7 times or more. [9] A heat-shrinkable film or heat-shrinkable sheet made of the film or sheet according to [8].

[10] A co-extrusion blow-molded container comprising a layer made of the resin composition according to any one of [1] to [5] and a layer made of a thermoplastic resin.

[11] An extrusion-molded product comprising the resin composition according to any one of [1] to [5].

[12] A thermoformed product comprising the resin composition according to any one of [1] to [5].

[13] A fuel container comprising the resin composition according to any one of [1] to [5].

[0007] The resin composition of the present invention has high gas barrier properties and stretchability, and is resistant to water absorption under high humidity. Films obtained using such resin compositions have excellent gas barrier properties and are easy to open, even when used as food packaging materials and stored under high humidity conditions, because their low water absorption prevents a decrease in yield stress.

[0008] The present invention provides a resin composition containing modified EVOH (A) and EVOH (B), wherein the modified EVOH (A) contains structural units (Ia), (Ib), and (Ic) represented by the following formulae, and the contents (mol %) a, b, and c of the structural units (Ia), (Ib), and (Ic) satisfy the following formulae (1) to (3), the degree of saponification (DS) of the modified vinyl alcohol (A) represented by the following formula (4) is 90 mol % or more, and the EVOH (B) does not contain the structural unit (Ic) and has an ethylene unit content of 33 to 54 mol % and a saponification degree of 80 mol % or more, and the mass ratio (A / B) of the modified EVOH (A) to the EVOH (B) is 30 / 70 to 95 / 5. The resin composition has high gas barrier properties and stretchability, and is resistant to water absorption under high humidity. Films obtained using such resin compositions have excellent gas barrier properties, and when used as food packaging materials, etc., they have low water absorption and suppress a decrease in yield stress, even when stored under high humidity conditions, resulting in good openability.

[0009] [In the formula, a, b, and c represent the content (mol %) of each structural unit relative to 100 mol % of the total of all structural units, and W represents a hydrogen atom, a methyl group, or R ２ -OY, and X, Y, and Z each independently represent a hydrogen atom, a formyl group, or an alkanoyl group having 2 to 10 carbon atoms. １ , R ２ each independently represents a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms, and the alkylene group and the alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom. * represents a bonding site. ] 33≦a≦54 (1) 0.1≦c<3 (2) [100-(a+c)]×0.9≦b≦[100-(a+c)] (3) DS=[(total number of moles of X, Y, and Z that are hydrogen atoms) / (total number of moles of X, Y, and Z)]×100 (4)

[0010] [Modified Ethylene-Vinyl Alcohol Copolymer (A)] The modified EVOH (A) contained in the resin composition contains structural units (Ia), (Ib) and (Ic) represented by the following formulae:

[0011] [In the formula, a, b, and c represent the content (mol %) of each structural unit relative to 100 mol % of the total of all structural units, and W represents a hydrogen atom, a methyl group, or R ２ -OY, and X, Y, and Z each independently represent a hydrogen atom, a formyl group, or an alkanoyl group having 2 to 10 carbon atoms. １ , R ２ each independently represents a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms, and the alkylene group and the alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom. * represents a bonding site.]

[0012] In the present invention, the modified EVOH (A) contains the structural units (Ia), (Ib), and (Ic) represented by the above formula, and the contents (mol %) a, b, and c of the structural units (Ia), (Ib), and (Ic) satisfy the following formulas (1) to (3): 33≦a≦54 (1) 0.1≦c<3 (2) [100−(a+c)]×0.9≦b≦[100−(a+c)] (3)

[0013] In the present invention, the degree of saponification (DS) of the modified EVOH (A) is expressed by the following formula (4), and the degree of saponification (DS) is 90 mol% or more: DS = [(total number of moles of X, Y, and Z that are hydrogen atoms) / (total number of moles of X, Y, and Z)] × 100 (4).

[0014] The modified EVOH (A) used in the present invention has a structural unit (Ic) in addition to an ethylene unit (structural unit (Ia)) and a vinyl alcohol unit (structural unit (Ib), where X is a hydrogen atom). The structural unit (Ic) has the effect of preventing crystallization due to steric hindrance and acts to improve secondary processability such as stretchability. Furthermore, since the modified EVOH (A) has primary hydroxyl groups, it exhibits high gas barrier properties due to strong hydrogen bonding strength.

[0015] In the structural unit (Ic), W is preferably a hydrogen atom or R ２ is a group represented by —OH, and more preferably R ２ It is a group represented by —OH. ２The group represented by —OH is preferably a hydroxyalkyl group (R ２ is an alkylene group).

[0016] In the structural unit (Ic), R １ , R ２ each independently represents a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms. The alkylene group and alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom. The alkylene group preferably has 5 or less carbon atoms, more preferably 3 or less, and even more preferably 2 or less carbon atoms. The alkyleneoxy group preferably has 5 or less carbon atoms, more preferably 3 or less, and even more preferably 2 or less carbon atoms.

[0017] In the structural units (Ib) and (Ic), when X, Y, or Z is a hydrogen atom, the modified EVOH (A) has a hydroxyl group, and when X, Y, or Z is a formyl group or an alkanoyl group, the modified EVOH (A) has an ester group. The alkanoyl group is preferably an alkanoyl group having 2 to 5 carbon atoms, more preferably an acetyl group, a propanoyl group, or a butanoyl group, and even more preferably an acetyl group. It is preferable that X, Y, and Z are all hydrogen atoms or a mixture containing hydrogen atoms.

[0018] Examples of the structural unit (Ic) include structural units (IIc), (IIIc) and (IVc) represented by the following formulae, with the structural unit (IIc) being preferred.

[0019] [In the structural unit (IIc), R ３ and R ４ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the alkyl group may contain a hydroxyl group, an alkoxy group, or a halogen atom.

[0020] [In the structural unit (IIIc), R ５ has the same meaning as W in the structural unit (Ic). ６ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the alkyl group may contain a hydroxyl group, an alkoxy group, or a halogen atom.

[0021] [In the structural unit (IVc), R ７ and R ８ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or a hydroxyl group, and the alkyl group and the cycloalkyl group may contain a hydroxyl group, an alkoxy group, or a halogen atom.

[0022] In the structural unit (Ic), (1) R １ is a single bond, W is a hydroxymethyl group (R ３ , R ４ is a hydrogen atom), (2) R １ is a hydroxymethylene group, W is a hydrogen atom (R ５ , R ６ is a hydrogen atom), or (3) R １ is a methylmethyleneoxy group, W is a hydrogen atom (R ７ , R ８ One of the groups is a methyl group and the other is a hydrogen atom), and among these, (1) is preferred.

[0023] In modified EVOH (A), a represents the content (mol %) of (Ia) relative to all structural units, and the content a of (Ia) is 33 to 54 mol % (Equation (1)). When the content a is 33 mol % or more, the resin composition is less likely to absorb water under high humidity. Therefore, when the resulting film is used as a food packaging material or the like and stored under high humidity, a decrease in yield stress is suppressed, resulting in good openability. Furthermore, because water absorption is suppressed, a decrease in gas barrier property is suppressed even when the resin composition is stored under high humidity. The content a is preferably 34 mol % or more, more preferably 35 mol % or more, even more preferably 36 mol % or more, and particularly preferably 37 mol % or more. On the other hand, when the content a is 54 mol % or less, the gas barrier property of the resin composition under low humidity (e.g., 65% humidity) is improved. The content a is preferably 50 mol% or less, more preferably 46 mol% or less, even more preferably 44 mol% or less, even more preferably 42 mol% or less, and particularly preferably 40 mol% or less.

[0024] In the modified EVOH (A), c represents the content (mol %) of (Ic) relative to all structural units, and is 0.1 mol % or more but less than 3 mol % (Equation (2)). When the content c is 0.1 mol % or more, the stretchability of the resin composition is improved. The content c is preferably 0.3 mol % or more, more preferably 0.5 mol % or more, even more preferably 0.8 mol % or more, and particularly preferably 1.0 mol % or more, and in some cases 1.2 mol % or more is preferred. On the other hand, when the content c is less than 3 mol %, the resin composition is less likely to absorb water under high humidity. Therefore, when the resulting film is used as a food packaging material or the like and stored under high humidity, the decrease in yield stress is suppressed, resulting in good openability. Furthermore, because water absorption is suppressed, the deterioration of gas barrier properties is suppressed even when the resin composition is stored under high humidity. The content c is preferably 2.7 mol% or less, more preferably 2.5 mol% or less, even more preferably 2.3 mol% or less, particularly preferably 2 mol% or less, and in some cases 1.8 mol% or less or 1.7 mol% or less is preferred.

[0025] In modified EVOH (A), b represents the content (mol %) of (Ib) relative to all structural units, and b satisfies formula (3). If b does not satisfy formula (3), the gas barrier properties of the resin composition will be insufficient. b preferably satisfies the following formula (3'), and more preferably the following formula (3"). When X in the structural unit (Ib) is two or more functional groups selected from the group consisting of a hydrogen atom, a formyl group, and an alkanoyl group having 2 to 10 carbon atoms (i.e., when the structural unit (Ib) contains both a vinyl alcohol unit and a vinyl ester unit), b is the sum of these functional groups. [100 - (a + c)] x 0.95 < b < [100 - (a + c)] (3') [100 - (a + c)] x 0.98 < b < [100 - (a + c)] (3").

[0026] In the modified EVOH (A), the degree of saponification (DS) is defined by formula (4), and the degree of saponification (DS) is 90 mol% or more. Here, "the total number of moles of hydrogen atoms among X, Y, and Z" refers to the number of moles of hydroxyl groups, and "the total number of moles of X, Y, and Z" refers to the total number of moles of hydroxyl groups and ester groups. If the degree of saponification (DS) is less than 90 mol%, the gas barrier properties of the resin composition will be insufficient. The degree of saponification (DS) is preferably 95 mol% or more, more preferably 98 mol% or more, even more preferably 99 mol% or more, even more preferably 99.5 mol% or more, and particularly preferably 99.8 mol% or more. The degree of saponification (DS) is usually 100 mol% or less.

[0027] The degree of saponification (DS) can be obtained by nuclear magnetic resonance (NMR). The contents (mol %) of each structural unit a, b, and c can also be obtained by NMR. The modified EVOH (A) used in the present invention is usually a random copolymer. The fact that it is a random copolymer can be confirmed from the results of NMR and melting point measurements.

[0028] The melt flow rate (MFR) (190°C, under a load of 2160 g) of the modified EVOH (A) is preferably 0.1 to 30 g / 10 min, more preferably 0.3 to 25 g / 10 min, and even more preferably 0.5 to 20 g / 10 min. However, for those having a melting point near or exceeding 190°C, the MFR is measured under a load of 2160 g at multiple temperatures equal to or higher than the melting point, and the MFR is plotted on a semi-logarithmic graph with the reciprocal of absolute temperature on the horizontal axis and the logarithm of the MFR on the vertical axis, and the value is expressed as an extrapolated value to 190°C.

[0029] [Production of Modified EVOH (A)] Next, the production of modified EVOH (A) will be described. For example, a method for producing modified EVOH (A) containing structural unit (IIc) includes radically polymerizing ethylene, a vinyl ester represented by formula (V) below, and an unsaturated monomer represented by formula (VI) below to obtain a modified ethylene-vinyl ester copolymer represented by formula (VII) below, and then saponifying the copolymer. This production method will be described below. EVOH (B) can be obtained in the same manner as this method except that the unsaturated monomer represented by formula (VI) below is not used.

[0030]

[0031] In formula (V), R ９ represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 4. Examples of vinyl esters represented by formula (V) include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, and vinyl caproate. From an economical viewpoint, vinyl acetate is more preferable.

[0032]

[0033] In formula (VI), R ３ and R ４ is the same as the structural unit (IIc). １０ and R １１ each independently represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 4. Examples of the unsaturated monomer represented by formula (VI) include 2-methylene-1,3-propanediol diacetate, 2-methylene-1,3-propanediol dipropionate, and 2-methylene-1,3-propanediol dibutyrate. Among these, 2-methylene-1,3-propanediol diacetate is preferably used because of its ease of production. In the case of 2-methylene-1,3-propanediol diacetate, R ３ and R ４ is a hydrogen atom, and R １０ and R １１ is a methyl group.

[0034]

[0035] In formula (VII), R ３ , R ４ , R ９ , R １０ and R １１are the same as in formulas (II), (V), and (VI). In formula (VII), a, b, and c represent the contents (mol %) of ethylene units, vinyl ester units, and units derived from the unsaturated monomer represented by formula (VI) relative to 100 mol % of the total of all structural units. The modified ethylene-vinyl ester copolymer thus obtained is then subjected to a saponification treatment.

[0036] In place of the unsaturated monomer represented by the formula (VI), an unsaturated monomer represented by the following formula (VIII) may be copolymerized. In this case, the unsaturated monomer represented by the formula (VIII) may be copolymerized by saponification treatment. ９ Only the vinyl ester units containing

[0037]

[0038] In formula (VIII), R ３ and R ４ is the same as the structural unit (IIc). Examples of the unsaturated monomer represented by formula (VIII) include 2-methylene-1,3-propanediol and 2-methylene-1,3-butanediol.

[0039] The unsaturated monomers represented by formulas (VI) and (VIII) have high copolymerization reactivity with vinyl ester monomers, and therefore the copolymerization reaction proceeds easily. Therefore, it is easy to increase the degree of modification and polymerization of the resulting modified ethylene-vinyl ester copolymer. Furthermore, even if the polymerization reaction is terminated at a low polymerization rate, the amount of unreacted unsaturated monomer remaining at the end of the polymerization is small, making the process environmentally and cost-effective. In this respect, the unsaturated monomers represented by formulas (VI) and (VIII) are superior to other monomers containing only one carbon atom bearing a functional group at the allylic position, such as allyl glycidyl ether and 3,4-diacetoxy-1-butene. Here, the unsaturated monomer represented by formula (VI) is more reactive than the unsaturated monomer represented by formula (V).

[0040] The polymerization method for producing a modified ethylene-vinyl ester copolymer by copolymerizing ethylene, a vinyl ester represented by the above formula (V), and an unsaturated monomer represented by the above formula (VI) or (VIII) may be any of batch polymerization, semi-batch polymerization, continuous polymerization, and semi-continuous polymerization. Furthermore, known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used. Bulk polymerization or solution polymerization, in which polymerization proceeds without a solvent or in a solvent such as alcohol, is usually used. When obtaining a modified ethylene-vinyl ester copolymer with a high degree of polymerization, emulsion polymerization is one option.

[0041] The solvent used in the solution polymerization method is not particularly limited, but examples thereof include alcohols, and lower alcohols such as methanol, ethanol, propanol, etc. are more preferred. The amount of solvent used in the polymerization reaction solution may be selected taking into consideration the viscosity-average degree of polymerization of the desired modified EVOH and chain transfer of the solvent. The mass ratio of the solvent to the total monomers contained in the reaction solution (solvent / total monomers) is usually in the range of 0.01 to 10, preferably in the range of 0.03 to 3, and more preferably in the range of 0.05 to 1.

[0042] The polymerization initiator used in copolymerizing ethylene, the vinyl ester represented by the formula (V) above, and the unsaturated monomer represented by the formula (VI) or (VIII) above is selected from known polymerization initiators, such as azo initiators, peroxide initiators, and redox initiators, depending on the polymerization method. Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). Examples of peroxide initiators include percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; perester compounds such as t-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, and acetyl peroxide; acetylcyclohexylsulfonyl peroxide; and 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate. Potassium persulfate, ammonium persulfate, hydrogen peroxide, and the like may also be combined with the above initiators. Redox initiators are polymerization initiators that combine, for example, the above peroxide initiators with reducing agents such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, and Rongalit. The amount of polymerization initiator used is adjusted depending on the polymerization rate. The amount of polymerization initiator used is preferably 0.01 to 0.2 mol, more preferably 0.02 to 0.15 mol, per 100 mol of vinyl ester monomer. The polymerization temperature is not particularly limited, but is suitably from room temperature to about 150°C, and preferably from 40°C to 100°C.

[0043] When copolymerizing ethylene, a vinyl ester represented by the above formula (V), and an unsaturated monomer represented by the above formula (VI) or (VIII), the copolymerization may be carried out in the presence of a chain transfer agent, as long as the effects of the present invention are not impaired. Examples of chain transfer agents include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; mercaptans such as 2-hydroxyethanethiol; and phosphinates such as sodium phosphinate monohydrate. Among these, aldehydes and ketones are preferred. The amount of chain transfer agent added to the polymerization reaction solution is determined depending on the chain transfer coefficient of the chain transfer agent and the degree of polymerization of the desired modified ethylene-vinyl ester copolymer, but is generally preferably 0.1 to 10 parts by mass per 100 parts by mass of vinyl ester monomer.

[0044] The modified ethylene-vinyl ester copolymer thus obtained can be saponified to obtain modified EVOH (A). During this process, the vinyl ester units in the copolymer are converted to vinyl alcohol units. The ester bonds derived from the unsaturated monomer represented by formula (VI) are also simultaneously hydrolyzed and converted to a 1,3-diol structure. Thus, different types of ester groups can be simultaneously hydrolyzed in a single saponification reaction.

[0045] Known methods can be used to saponify the modified ethylene-vinyl ester copolymer. The saponification reaction is usually carried out in an alcohol or aqueous alcohol solution. The preferred alcohols are lower alcohols such as methanol and ethanol, more preferably methanol. The alcohol or aqueous alcohol used in the saponification reaction may contain other solvents such as acetone, methyl acetate, ethyl acetate, and benzene, as long as the amount is 40% by mass or less. Catalysts used in saponification include, for example, alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, alkali catalysts such as sodium methylate, and acid catalysts such as mineral acids. The temperature at which saponification is carried out is not limited, but a temperature in the range of 20 to 120°C is preferred. If a gel-like product precipitates as the saponification proceeds, the product can be pulverized, washed, and dried to obtain modified EVOH.

[0046] The modified EVOH (A) may contain structural units derived from other ethylenically unsaturated monomers copolymerizable with ethylene, the vinyl ester represented by the above formula (V), and the unsaturated monomer represented by the above formula (VI) or (VIII), to the extent that the effects of the present invention are not impaired. Examples of such other ethylenically unsaturated monomers include α-olefins such as propylene, n-butene, isobutylene, and 1-hexene; acrylic acid and its salts; unsaturated monomers having an acrylic ester group; methacrylic acid and its salts; unsaturated monomers having a methacrylic ester group; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts (e.g., quaternary salts); methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts (e.g., quaternary salts); methyl vinyl ether, vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, and allyl chloride; unsaturated dicarboxylic acids and salts or esters thereof such as maleic acid, itaconic acid, and fumaric acid; vinylsilane compounds such as vinyltrimethoxysilane; and isopropenyl acetate.

[0047] The method for producing the modified EVOH (A) containing the structural unit (IIIc) is not particularly limited, and examples thereof include a method of saponifying a copolymer obtained by copolymerizing 3,4-diol-1-butene, a vinyl ester monomer, and ethylene, a method of saponifying a copolymer obtained by copolymerizing 3,4-diacyloxy-1-butene, a vinyl ester monomer, and ethylene, a method of saponifying a copolymer obtained by copolymerizing 3-acyloxy-4-ol-1-butene, a vinyl ester monomer, and ethylene, a method of saponifying a copolymer obtained by copolymerizing 4-acyloxy-3-ol-1-butene, a vinyl ester monomer, and ethylene, and a method of saponifying a copolymer obtained by copolymerizing 3,4-diacyloxy-2-methyl-1-butene, a vinyl ester monomer, and ethylene. The modified EVOH (A) containing the structural unit (IIIc) can be obtained by the same method as that for the modified EVOH (A) containing the structural unit (IIc), except that the monomer used to form the structural unit (IIIc) is different.

[0048] The 3,4-diol-1-butene is represented by the following formula (IX), the 3,4-diacyloxy-1-butene by the following formula (X), the 3-acyloxy-4-ol-1-butene by the following formula (XI), and the 4-acyloxy-3-ol-1-butene by the following formula (XII).

[0049]

[0050]

[0051] Here, R １２ is an alkyl group, preferably a methyl group.

[0052]

[0053] Here, R １３ is an alkyl group, preferably a methyl group.

[0054]

[0055] Here, R １４ is an alkyl group, preferably a methyl group.

[0056] The method for producing modified EVOH (A) containing structural unit (IVc) is not particularly limited, and examples thereof include a method of reacting EVOH having an ethylene unit content of 34 to 55 mol% with a monofunctional epoxy compound described below. The reaction method is not particularly limited, and preferred methods include a production method of reacting EVOH with a monofunctional epoxy compound in a solution and a production method of reacting EVOH with a monofunctional epoxy compound in an extruder.

[0057] In the solution reaction production method, a modified EVOH is obtained by reacting a monofunctional epoxy compound with an EVOH solution in the presence of an acid catalyst or an alkali catalyst. Alternatively, modified EVOH (A) can be produced by dissolving EVOH and a monofunctional epoxy compound in a reaction solvent and subjecting the mixture to heat treatment. Preferred reaction solvents are polar aprotic solvents that are good solvents for EVOH, such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0058] Examples of reaction catalysts include acid catalysts such as p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, and boron trifluoride, and alkali catalysts such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium methoxide. Of these, acid catalysts are preferred. The appropriate amount of catalyst is approximately 0.0001 to 10 parts by mass per 100 parts by mass of EVOH. The appropriate reaction temperature is room temperature to 150°C.

[0059] In the production method in which EVOH and a monofunctional epoxy compound are reacted in an extruder, there are no particular limitations on the extruder used, but examples include a single-screw extruder, a twin-screw extruder, and a multi-screw extruder with two or more screws. It is also preferable to react EVOH and a monofunctional epoxy compound at a temperature of approximately 200°C to 300°C. When a twin-screw extruder or a multi-screw extruder with two or more screws is used, it is easy to increase the pressure in the reaction zone by changing the screw configuration, allowing the reaction between EVOH and a monofunctional epoxy compound to be carried out efficiently. In the case of a single-screw extruder, the pressure in the reaction zone can be increased by connecting two or more extruders and arranging a valve in the resin flow path between them. Similarly, production may also be carried out by connecting two or more twin-screw extruders or two or more multi-screw extruders.

[0060] A monofunctional epoxy compound is an epoxy compound having only one epoxy group in the molecule.

[0061] The monofunctional epoxy compound used in the present invention is not particularly limited, but specifically, compounds represented by the following formulae (XIII) to (XV) are preferably used.

[0062]

[0063]

[0064]

[0065] In the formula, R １５ , R １６ and R １７ represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a cycloalkyl group having 3 to 7 carbon atoms. Also, i represents an integer of 1 to 7.

[0066] The number of carbon atoms in the monofunctional epoxy compound is particularly preferably 2 to 8. From the viewpoint of the gas barrier properties of the resulting modified EVOH, 1,2-epoxybutane, epoxypropane, epoxyethane and glycidol are more preferred as the monofunctional epoxy compound, and epoxypropane and glycidol are even more preferred.

[0067] Modified EVOH can be obtained by reacting EVOH with a monofunctional epoxy compound. The mixing ratio of the monofunctional epoxy compound to 100 parts by mass of EVOH is preferably 1 to 50 parts by mass.

[0068] In the resin composition of the present invention, the modified EVOH (A) obtained as described above is blended with EVOH (B). Here, the EVOH (B) used in the present invention refers to an EVOH that does not contain the structural unit (Ic), and any general-purpose EVOH that has been widely used in the past can be used.

[0069] The ethylene unit content of EVOH (B) is 33 to 54 mol%. An ethylene unit content of 33 mol% or more reduces the water absorption of the resin composition under high humidity conditions. Therefore, when the resulting film is used as a food packaging material or the like and stored under high humidity conditions, a decrease in yield stress is suppressed, resulting in good openability. Furthermore, because water absorption is suppressed, a decrease in gas barrier properties is suppressed even when the resin composition is stored under high humidity conditions. The ethylene unit content is preferably 34 mol% or more, more preferably 35 mol% or more, even more preferably 36 mol% or more, and particularly preferably 37 mol% or more. From the viewpoints of improving stretchability and further suppressing water absorption, an ethylene unit content of 40 mol% or more, 44 mol% or more, or 45 mol% or more may be preferred. On the other hand, an ethylene unit content of 54 mol% or less improves the gas barrier properties of the resin composition under low humidity conditions (e.g., 65% humidity). The ethylene unit content is preferably 50 mol% or less, more preferably 46 mol% or less, even more preferably 44 mol% or less, and particularly preferably 42 mol% or less. The "ethylene unit content" means the content (mol%) of structural units derived from ethylene relative to the total of all structural units (100 mol%).

[0070] The saponification degree of EVOH (B) is 80 mol% or more. The saponification degree is the proportion of saponified units among the copolymerized vinyl ester units. If the saponification degree is less than 80 mol%, the gas barrier property of the resin composition becomes insufficient. The saponification degree is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 98 mol% or more, even more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and most preferably 99.8 mol% or more. The saponification degree is usually 100 mol% or less. The ethylene unit content and saponification degree of EVOH (B) are 1 It is determined by H-NMR measurement.

[0071] EVOH (B) may contain a small amount of structural units derived from other ethylenically unsaturated monomers copolymerizable with ethylene and the vinyl ester represented by formula (V) as long as the effects of the present invention are not impaired. Examples of such other ethylenically unsaturated monomers include those exemplified in the description of modified EVOH (A). The content of structural units derived from other ethylenically unsaturated monomers is usually 10 mol % or less, preferably 5 mol % or less, and more preferably 2 mol % or less, of the total structural units. It is even more preferable that the EVOH (B) is substantially free of structural units derived from other ethylenically unsaturated monomers.

[0072] The melt flow rate (MFR) of EVOH (B) (at 190°C under a load of 2160 g) is preferably 0.1 to 30 g / 10 min, more preferably 0.3 to 25 g / 10 min, and even more preferably 0.5 to 20 g / 10 min. However, for EVOH (B) with a melting point near or exceeding 190°C, the MFR is measured under a load of 2160 g at multiple temperatures equal to or higher than the melting point, and the MFR is plotted on a semi-logarithmic graph with the reciprocal of absolute temperature on the horizontal axis and the logarithm of the MFR on the vertical axis, and the value is expressed as an extrapolated value to 190°C.

[0073] In the resin composition of the present invention, the mass ratio (A / B) of the modified EVOH (A) to the EVOH (B) is 30 / 70 to 95 / 5. A mass ratio (A / B) of 30 / 70 or more improves the stretchability of the resin composition. The mass ratio (A / B) is preferably 40 / 60 or more, more preferably 45 / 55 or more, and even more preferably 55 / 65 or more. In some cases, 65 / 45 or more, 70 / 30 or more, or 75 / 25 or more is preferred. On the other hand, a mass ratio (A / B) of 95 / 5 or less reduces the resin composition's resistance to water absorption under high humidity. Therefore, when the resulting film is used as a food packaging material or the like and stored under high humidity, a decrease in yield stress is suppressed, resulting in good openability. Furthermore, because water absorption is suppressed, a decrease in gas barrier properties is suppressed even when the resin composition is stored under high humidity. The mass ratio (A / B) is preferably 90 / 10 or less, more preferably 85 / 15 or less, and in some cases is 75 / 25 or less or 70 / 30 or less.

[0074]

[0003] Conventional methods for improving the stretchability, etc., of EVOH include using modified EVOH, which is EVOH containing a specific structural unit having a primary hydroxyl group, and using a resin composition in which a small amount of the modified EVOH with a relatively high degree of modification is added to unmodified EVOH. However, when films obtained using these modified EVOHs or resin compositions containing modified EVOH and unmodified EVOH are used as packaging materials for meat and the like and stored under high humidity for a long period of time, the films often absorb water, resulting in a decrease in yield stress and making them difficult to open.

[0004] The present inventors conducted extensive research to solve this problem and surprisingly found that adding a small amount of EVOH not containing the structural unit (Ic) to modified EVOH (A) having a relatively high content of ethylene units (structural unit (Ia)) and a low modification level (content of structural unit (Ic)) makes the resin composition less likely to absorb water under high humidity. When a film obtained using such a resin composition is used as a food packaging material or the like and stored under high humidity conditions, it is less likely to absorb water and the decrease in yield stress is suppressed, resulting in good openability.

[0075] The resin composition of the present invention may contain other additives in addition to the modified EVOH (A) and EVOH (B). For example, thermoplastic resins other than EVOH, plasticizers, lubricants, stabilizers, surfactants, colorants, UV absorbers, antistatic agents, desiccants, crosslinking agents, metal salts, fillers, and reinforcing agents such as various fibers may be blended. The content of components other than the modified EVOH (A) and EVOH (B) in the resin composition of the present invention is usually less than 50% by mass, preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and may even be 1% by mass or less.

[0076] The resin composition of the present invention may contain an alkali metal salt. In this case, the content of the alkali metal salt in the resin composition is usually 10 to 500 ppm by mass in terms of the alkali metal element. The resin composition of the present invention may contain a phosphate compound. In this case, the content of the phosphate compound in the resin composition is usually 5 to 200 ppm by mass in terms of phosphate radical. The resin composition of the present invention may contain a boron compound. In this case, the content of the boron compound in the resin composition is usually 20 to 2000 ppm by mass in terms of boron element.

[0077] The resin composition of the present invention has an oxygen transmission rate of 20 cc·20 μm / m at 20° C. and 65% RH. ２ The oxygen transmission rate is preferably less than 10 cc·day·atm. The oxygen transmission rate is more preferably less than 10 cc·20 μm / m. ２ · day · atm, and more preferably less than 5 cc · 20 μm / m ２ ·day·atm, and even more preferably less than 1.7 cc·20 μm / m ２ ・day・atm, and particularly preferably 0.9 cc・20 μm / m ２ The oxygen transmission rate of the resin composition at 20°C and 65% RH is measured by the method described in the examples.

[0078] The resin composition of the present invention preferably has a water absorption rate of 6.5% by mass or less when immersed in water at 20°C for 2 hours. This improves the yield stress of a film obtained using the resin composition after being kept under high humidity, making the film easier to open when used as a food packaging material, etc. Furthermore, even when the resin composition is stored under high humidity, deterioration of the gas barrier properties is suppressed. The water absorption rate is more preferably 6.3% by mass or less, even more preferably 6.05% by mass or less, even more preferably 5.8% by mass or less, and particularly preferably 5.5% by mass or less. Meanwhile, the water absorption rate is usually 0.5% by mass or more. The water absorption rate is measured by the method described in the Examples.

[0079] The resin composition of the present invention has an oxygen transmission rate of 50 cc·20 μm / m at 20° C. and 65% RH after being immersed in water at 20° C. for 2 hours. ２ In this case, the oxygen transmission rate is preferably less than 40 cc·day·atm. More preferably, the oxygen transmission rate is less than 40 cc·20 μm / m. ２ · day · atm, and more preferably less than 37 cc · 20 μm / m ２ ・day・atm or less, and particularly preferably 30cc・20μm / m ２ The oxygen transmission rate is less than 1 / 2 day atm. Even when stored under such high humidity conditions, the resin composition has good gas barrier properties and is suitable for a wide range of applications, including packaging materials such as food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, and agricultural chemical packaging materials; fuel containers, etc. The oxygen transmission rate is measured by the method described in the examples.

[0080] From a safety standpoint, it is preferable that the content of components having a weight-average molecular weight of 200 or more but less than 1,000 in the resin composition of the present invention be 5% by mass or less. Such components are derived from oligomers, etc., generated during the production of modified EVOH (A). Generally, increasing the modification amount (content of structural unit (Ic)) for the purpose of improving stretchability, etc., makes such oligomers more likely to be generated during polymerization. On the other hand, the resin composition of the present invention can achieve high stretchability by using a modified EVOH (A) with a relatively low modification amount, thereby enabling a reduction in the oligomer content. The content of the above components in the resin composition is more preferably 0.21% by mass or less, and even more preferably 0.15% by mass or less. The content of components having a weight-average molecular weight of 200 or more but less than 1,000 in the resin composition is measured by the method described in the Examples. There are no particular limitations on the method for adjusting the content of components having a weight-average molecular weight of 200 or more but less than 1,000 in the resin composition to the above upper limit or less. For example, a method can be used in which powdery modified EVOH (A) is thoroughly washed under heating.

[0081] The method for producing the resin composition of the present invention is not particularly limited. It is preferable to produce modified EVOH (A) and then mix it with EVOH (B). The mixing method is not particularly limited, but they are usually mixed in a molten state. The melt-mixing method is not particularly limited, and an extruder, an intensive mixer, a Banbury mixer, a kneader, or the like can be used. At this time, the various additives described above can also be added simultaneously and kneaded. Alternatively, a resin composition containing modified EVOH (A) and EVOH (B) can be produced by polymerizing a modified ethylene-vinyl ester copolymer and an ethylene-vinyl ester copolymer separately, mixing them in solution, and saponifying the mixture. Modified EVOH (A) and EVOH (B) can also be dissolved in a solvent such as an aqueous alcohol solution and mixed.

[0082] When an alkali metal salt, a phosphate compound, or a boron compound is blended into the resin composition of the present invention, a method is preferred in which at least one of the modified EVOH (A) and EVOH (B) resins is contacted with an aqueous solution containing the alkali metal salt, the phosphate compound, or the boron compound, and then the two resins are mixed. In this case, it is also possible to contact either the modified EVOH (A) or the EVOH (B) with an aqueous solution containing these components, and then mix it with the other resin that does not contain these components. However, in order to obtain a stable addition effect, it is preferable to contact both resins with the aqueous solution and then mix the two resins.

[0083] The method for molding the resin composition of the present invention is not particularly limited. Although molding can be performed using a solution of the resin composition, melt molding is preferred. Examples of melt molding methods include extrusion molding, injection molding, inflation molding, press molding, and blow molding. Among these, extrusion molding is a preferred molding method, and various extrusion molded products can be obtained.

[0084] A preferred embodiment of the resin composition of the present invention is a barrier material. The resin composition of the present invention has excellent barrier properties against gases such as oxygen, as well as against fuels such as gasoline and various chemicals.

[0085] By melt molding the resin composition of the present invention, various molded products such as films, sheets, containers, pipes, fibers, etc. can be obtained. In particular, films and sheets having a layer made of the resin composition of the present invention are suitable for applications in which flexibility is required and stretching is often performed after melt molding. Here, the film and sheet may be a single-layer product made of the resin composition of the present invention, or may be a multilayer structure containing another thermoplastic resin layer.

[0086] Molded articles made from the resin composition of the present invention are often used as multilayer structures in which a layer made from the resin composition and a layer made from a thermoplastic resin other than EVOH are laminated. Here, "thermoplastic resin other than EVOH" refers to a broad concept that includes modified EVOH (A) and EVOH (B). A particularly preferred configuration is one in which a layer of the resin composition of the present invention is used as an intermediate layer, with other thermoplastic resins arranged as outer layers on both sides. It is also preferred that the resin composition layer and the other thermoplastic resin layer are bonded via an adhesive resin layer. The resin composition layer of the present invention provides barrier properties and typically has a thickness of 3 to 250 μm, preferably 10 to 100 μm. Meanwhile, the thermoplastic resin used in the outer layer is not particularly limited and can be appropriately selected taking into account the required performance and application, such as moisture permeability, heat resistance, heat sealability, and transparency. The overall thickness of the multilayer structure is not particularly limited, but is typically 15 to 6,000 μm. Suitable embodiments of such multilayer structures include multilayer films or sheets, co-extrusion blow-molded containers, and coinjection blow-molded containers.

[0087] Examples of other thermoplastic resin layers to be laminated with the layer made of the resin composition of the present invention include polyolefins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer; polyamides; polyesters; polystyrene; polyvinyl chloride; acrylic resins; polyvinylidene chloride; polyacetal; and polycarbonates.

[0088] The multilayer structure can be obtained by various manufacturing methods, including coextrusion, dry lamination, sand lamination, extrusion lamination, coextrusion lamination, and solution coating. Among these, the coextrusion method involves simultaneously extruding the resin composition of the present invention and another thermoplastic resin from an extruder, laminating them in a molten state, and discharging them from a die outlet into a multilayer film. When forming a film by coextrusion, a method in which a layer of the resin composition of the present invention and another thermoplastic resin layer are laminated with an adhesive resin layer sandwiched therebetween is preferred. As the adhesive resin, a polyolefin having a carboxyl group, a carboxylic anhydride group, or an epoxy group is preferably used. Such adhesive resins have excellent adhesion to both the resin composition of the present invention and other thermoplastic resins that do not contain a carboxyl group, a carboxylic anhydride group, or an epoxy group.

[0089] Examples of polyolefins containing carboxyl groups include polyolefins copolymerized with acrylic acid or methacrylic acid. In this case, all or part of the carboxyl groups contained in the polyolefin may be present in the form of a metal salt, as typified by ionomers. Examples of polyolefins containing carboxylic anhydride groups include polyolefins graft-modified with maleic anhydride or itaconic acid. Examples of polyolefin resins containing epoxy groups include polyolefins copolymerized with glycidyl methacrylate. Among these polyolefins containing carboxyl groups, carboxylic anhydrides, or epoxy groups, polyolefins modified with carboxylic anhydrides such as maleic anhydride, particularly polyethylene and polypropylene, are preferred because of their excellent adhesive properties.

[0090] The melt-molded article thus obtained is preferably further subjected to secondary processing. Molded articles containing the resin composition of the present invention have excellent secondary processability. Examples of secondary processing methods include uniaxial stretching, biaxial stretching, stretch-blow molding, thermoforming, and rolling. In particular, a film or sheet stretched at a high stretching ratio is a preferred embodiment of the present invention. Specifically, a film or sheet stretched to an areal stretching ratio of 7 times or more (more preferably 11 times or more) is a particularly preferred embodiment. Thermoformed articles are also preferred embodiments of the present invention. Prior to secondary processing, crosslinking may be performed by irradiation or the like. Heat-shrinkable films or heat-shrinkable sheets are also preferred embodiments of the present invention. These can be produced by leaving the residual stress of the film or sheet stretched as described above without relaxing it. The melt-molded article subjected to secondary processing may be a single-layer article made of the resin composition of the present invention, or may be a multilayer structure containing other thermoplastic resin layers.

[0091] The molded article of the present invention thus obtained has excellent secondary processability, such as gas barrier properties and stretchability, and can be molded into various shapes such as films, cups, bottles, etc., and can be suitably used as various containers. The resin composition of the present invention is also suitable as a fuel container. Suitable fuel containers include co-extrusion blow-molded containers and thermoformed containers.

[0092] The present invention will be explained in more detail below using examples.

[0093] Synthesis Example 1 (1) Synthesis of Modified EVAc Vinyl acetate (in formula (V), R ９100 kg of methanol (hereinafter sometimes referred to as MeOH), 10 kg of 2-methylene-1,3-propanediol diacetate (hereinafter referred to as MPDAc) were charged, and the temperature was raised to 60°C. After that, nitrogen bubbling was performed for 30 minutes to replace the atmosphere inside the reactor with nitrogen. Ethylene was then introduced so that the reactor pressure (ethylene pressure) was 4.9 MPa. After adjusting the temperature inside the reactor to 60°C, 60 g of 2,2'-azobis(2,4-dimethylvaleronitrile) ("V-65" manufactured by Wako Pure Chemical Industries, Ltd.) was added as a methanol solution as an initiator to initiate polymerization. During the polymerization, the ethylene pressure was maintained at 4.9 MPa, and the polymerization temperature was maintained at 60°C. After 6 hours, when the conversion of VAc reached 45%, the polymerization was stopped by cooling. The reaction vessel was opened to remove ethylene, and then nitrogen gas was bubbled through to completely remove ethylene. Next, unreacted VAc was removed under reduced pressure, and a modified ethylene-vinyl acetate copolymer (in formula (VII), R ３ and R ４ is a hydrogen atom, and R ９ , R １０ and R １１ is a methyl group, hereinafter sometimes referred to as modified EVAc) was added to prepare a 20% by mass MeOH solution.

[0094] (2) Saponification of Modified EVAc A 20% by mass MeOH solution of the modified EVAc obtained in (1) was charged into a 500 L reaction vessel equipped with a jacket, a stirrer, a nitrogen inlet, a reflux condenser, and a solution addition port. The temperature of this solution was raised to 60°C while nitrogen was blown into it, and 0.5 equivalents of sodium hydroxide relative to the vinyl acetate units in the modified EVAc were added as a 2N MeOH solution. After the addition of the sodium hydroxide MeOH solution was completed, the temperature in the system was maintained at 60°C, and the saponification reaction was allowed to proceed for 2 hours while stirring and distilling off methyl acetate and MeOH. The saponification reaction was then stopped by adding acetic acid. Subsequently, ion-exchanged water was added while heating and stirring at 60 to 80°C, and MeOH was distilled out of the reaction vessel, resulting in the precipitation of modified EVOH. The precipitated modified EVOH was collected and pulverized in a mixer. The obtained modified EVOH powder was poured into water in an amount 20 times the mass of the modified EVOH and washed by stirring at 90°C for 2 hours, after which the hot water was removed. The same procedure was repeated twice. The washed modified EVOH powder was poured into a 1 g / L aqueous acetic acid solution (bath ratio 20: 20 L of aqueous solution per 1 kg of powder) and washed with stirring at 20°C for 2 hours. The powder was deliquored and further poured into a 1 g / L aqueous acetic acid solution (bath ratio 20) and washed with stirring at 20°C for 2 hours. The deliquored powder was poured into ion-exchanged water (bath ratio 20) and washed with stirring at 20°C for 2 hours, followed by deliquoring. This procedure was repeated three times for purification. Next, the powder was immersed in 10 L of an aqueous solution containing 0.5 g / L acetic acid and 0.1 g / L sodium acetate at 20°C with stirring for 4 hours, then deliquored. The powder was dried at 60°C for 16 hours and then at 110°C for 16 hours to obtain a modified EVOH. The resulting modified EVOH had a melt flow rate (MFR) (190° C., under a load of 2160 g) of 8.0 g / 10 min.

[0095] (3) Content of each structural unit in modified EVAc The content of ethylene units (a mol % in formula (VII)), the content of structural units derived from vinyl acetate (b mol % in formula (VII)), and the content of structural units derived from MPDAc (c mol % in formula (VII)) in modified EVAc were determined by comparing the modified EVAc before saponification with the modified EVAc before saponification. １ Calculation was performed by H-NMR measurement.

[0096] First, a small amount of the MeOH solution of modified EVAc obtained in (1) was sampled, and the modified EVAc was precipitated in ion-exchanged water. The precipitate was collected and dried at 60°C under vacuum to obtain a dried product of modified EVAc. Next, the dried product of modified EVAc was dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetramethylsilane as an internal standard substance, and analyzed by a 500 MHz spectrometer. １ Measurement was performed at 80°C using a H-NMR (manufactured by JEOL Ltd.: "GX-500").

[0097] Modified EVAc １ The peaks in the H-NMR spectrum are assigned as follows: 0.6 to 1.0 ppm: methylene protons (4H) of terminal ethylene units; 1.0 to 1.85 ppm: methylene protons (4H) of intermediate ethylene units, methylene protons (2H) of the main chain of structural units derived from MPDAc, and methylene protons (2H) of vinyl acetate units; 1.85 to 2.1 ppm: methyl protons (6H) of structural units derived from MPDAc and methyl protons (3H) of vinyl acetate units; 3.7 to 4.1 ppm: methylene protons (4H) of the side chain of structural units derived from MPDAc; 4.4 to 5.3 ppm: methine protons (1H) of vinyl acetate units.

[0098] According to the above attributions, when the integral value from 0.6 to 1.0 ppm is represented by x, the integral value from 1.0 to 1.85 ppm is represented by y, the integral value from 3.7 to 4.1 ppm is represented by z, and the integral value from 4.4 to 5.3 ppm is represented by w, the content of ethylene units (a: mol %), the content of vinyl ester units (b: mol %), and the content of structural units derived from MPDAc (c: mol %) are calculated according to the following formulas: a = (2x + 2y - z - 4w) / (2x + 2y + z + 4w) × 100 b = 8w / (2x + 2y + z + 4w) × 100 c = 2z / (2x + 2y + z + 4w) × 100

[0099] As a result of calculation using the above method, the content (a) of ethylene units in the modified EVAc in Synthesis Example 1 was 38.0 mol%, the content (b) of vinyl ester units was 60.5 mol%, and the content (c) of structural units derived from MPDAc was 1.5 mol%. The values ​​of a, b, and c in the modified EVAc are the same as the values ​​of a, b, and c in the modified EVOH after saponification.

[0100] (4) Degree of saponification of modified EVOH The same applies to the modified EVOH after saponification. １ The crude dried modified EVOH obtained in (2) above was dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetramethylsilane as an internal standard and tetrafluoroacetic acid (TFA) as an additive, and subjected to H-NMR measurement at 500 MHz. １ Measurement was performed at 80°C using a H-NMR (manufactured by JEOL Ltd.: "GX-500"). １ As a result of H-NMR measurement, the peak intensity between 1.85 and 2.1 ppm was significantly reduced, which clearly shows that in addition to the ester groups derived from vinyl acetate in the modified EVOH, the ester groups contained in the structural units derived from MPDAc were also saponified to hydroxyl groups. １ This decrease in peak intensity between 1.85 and 2.1 ppm was also observed in the H-NMR spectrum. The degree of saponification was calculated from the peak intensity ratio of the methyl protons of the vinyl acetate unit (1.85 to 2.1 ppm) to the methine protons of the vinyl alcohol unit (3.15 to 4.15 ppm). The degree of saponification of the modified EVOH of Synthesis Example 1 was 99.9 mol% or more.

[0101] Synthesis Examples 2 to 9 Modified EVOH and unmodified EVOH were synthesized as shown in Table 1 in the same manner as in Synthesis Example 1, except that the pressure in the tank during polymerization, the polymerization time, the amount of methanol added, and the amount of MPDAc added were changed. The ethylene unit content and the degree of saponification of the unmodified EVOH were as follows: 1 It was determined by H-NMR measurement.

[0102] Synthesis Example 11 (1) Synthesis of Modified EVAc A 20% by mass MeOH solution of modified EVAc was obtained in the same manner as in Synthesis Example 1. (2) Saponification of Modified EVAc A 20% by mass MeOH solution of the modified EVAc obtained in (1) was charged into a 500 L reaction vessel equipped with a jacket, a stirrer, a nitrogen inlet, a reflux condenser, and a solution addition port. The temperature of this solution was raised to 60°C while blowing nitrogen into it, and 0.05 equivalents of sodium hydroxide relative to the vinyl acetate units in the modified EVAc were added as a 2N MeOH solution. After the addition of the sodium hydroxide MeOH solution was completed, the system temperature was maintained at 60°C, and the saponification reaction was allowed to proceed with stirring for 20 hours while distilling off methyl acetate and MeOH. Thereafter, acetic acid was added to terminate the saponification reaction. The mixture was then dried under reduced pressure at 60°C to obtain a modified EVOH solid. The resulting modified EVOH solid was collected and pulverized in a mixer. The resulting mixture was then dried at 60° C. for 16 hours and then at 110° C. for 16 hours to obtain a modified EVOH. The resulting modified EVOH had a melt flow rate (MFR) of 9.0 g / 10 min (190° C., under a load of 2160 g).

[0103] Example 1 The modified EVOH obtained in Synthesis Example 1 and the unmodified EVOH obtained in Synthesis Example 5 were mixed by dry blending, and then melt-kneaded using a twin-screw extruder. The molten resin emerging from the die tip was extruded into water in the form of strands and cut into cylindrical pellets having a diameter of 3 mm and a length of 3 mm to obtain the target resin composition pellets. (Melt-kneading conditions) Extruder: Twin-screw extruder "Labo Plastomill" manufactured by Toyo Seiki Seisakusho, Ltd. Screw diameter: 25 mmφ L / D = 30 Screw rotation speed: 100 rpm Discharge rate: 5.0 kg / hr Cylinder and die temperature settings: C1 / C2 / C3 / C4 / C5 / Die = 150 / 200 / 200 / 200 / 200 / 200 (°C)

[0104]

[0046] Monolayer Film Formation

[0047] The resin composition pellets were fed into a single-screw extruder equipped with a full-flight screw having a screw diameter of 20 mm, a compression ratio of 3.5, and an L / D ratio of 26, and the molten resin was extruded onto a cooling roll in the form of a film to obtain a monolayer film having a thickness of 100 μm. For the water absorption test, biaxial stretching test, oligomer extraction test, oxygen permeability measurement test, and film cuttability evaluation, the monolayer film was cut into 10 cm square pieces and vacuum dried at 40°C for 24 hours to reduce the moisture content to less than 0.3%.

[0105] Biaxial Stretching Test: A 100 μm thick monolayer film cut into a 10 cm square was attached to a batch-type biaxial stretching machine and subjected to a simultaneous biaxial stretching test. The stretching ratios for simultaneous biaxial stretching were 2 × 2, 3 × 3, 3.25 × 3.25, 3.5 × 3.5, 3.75 × 3.75, 3.80 × 3.80, 3.85 × 3.85, 3.90 × 3.90, 3.95 × 3.95, and 4.0 × 4.0, and the stretching test was performed in this order. Three stretching tests were performed for each stretching ratio, and the maximum stretching ratio at which the film could be stretched two or more times without breaking was defined as the maximum biaxial stretching ratio, and the results were evaluated according to the following criteria. (Biaxial stretching conditions) Stretching machine: "Biaxial stretching birefringence phase difference measuring device" manufactured by Eto Corporation Preheating temperature: 90°C Preheating time: 120 seconds Stretching speed: 5 m / min (Standards) A: Maximum biaxial stretching magnification is 14 or more B: Maximum biaxial stretching magnification is 12.5 or more and less than 14 C: Maximum biaxial stretching magnification is 11 or more and less than 12.5 D: Maximum biaxial stretching magnification is 6 or more and less than 11 E: Maximum biaxial stretching magnification is less than 6

[0106] Water Absorption Test A 10 cm square, 100 μm thick monolayer film was vacuum dried at 40°C for 24 hours to reduce the moisture content to less than 0.3%, and then immersed in water at 20°C for 2 hours. The water absorption of the film was calculated using the following formula, using the film mass α (g) before immersion and the film mass β (g) after immersion. The test was performed with n=5, and the average value was taken as the "water absorption (mass%) of the resin composition after immersed in water for 2 hours." Water absorption of film (mass%) = 100 × (β - α) / α

[0107] Oligomer Extraction Test Ten 10 cm square, 100 μm thick monolayer films [total mass P (g)] that had been vacuum dried at 40 ° C for 24 hours to reduce the moisture content to less than 0.3% were added to a 1 L separable flask in a 70 ° C warm water bath, and hot water extraction was performed at 70 ° C for 2 hours. After hot water extraction, the 10 films were removed, and the water in the separable flask was distilled under reduced pressure. The separable flask was vacuum dried at 60 ° C for 12 hours to dry the extracted components, and the mass Q (g) of the components extracted by hot water extraction was measured. Furthermore, the extracted components were dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol containing 20 mM sodium trifluoroacetate, and the mass ratio R of components with a weight average molecular weight of 200 or more but less than 1,000 to the total extracted components was measured by gel permeation chromatography (GPC). The content S (mass%) of components having a weight-average molecular weight of 200 or more and less than 1,000 in the resin composition was calculated using the total mass P (g) of the 10 monolayer films after vacuum drying, the mass Q (g) of the dried extracted components, and the mass ratio R of the components having a weight-average molecular weight of 200 or more and less than 1,000 to the total extracted components, according to the following formula: Content S (mass%) = 100 × Q × R / P

[0108] (Gel Permeation Chromatography (GPC) Measurement Conditions) Apparatus: HLC-8320GPC (manufactured by Tosoh Corporation) Standard substance: polymethyl methacrylate Mobile phase: 1,1,1,3,3,3-hexafluoro-2-propanol solution containing 20 mM sodium trifluoroacetate Column: two GMHHR-H(S) columns in series Detector: refractive index detector Temperature: 40°C Flow rate: 0.2 mL / min Injection volume: 10 μL

[0109] Multilayer film formation test Using pellets of the EVOH resin composition obtained in Example 1, polyethylene resin ("Novatec™ LD LC600A" manufactured by Japan Polyethylene Co., Ltd.; low-density polyethylene, melting point 107°C), and polyethylene adhesive resin ("Admer™ NF518" manufactured by Mitsui Chemicals, Inc.; maleic anhydride-grafted linear low-density polyethylene adhesive resin, melting point 120°C), a symmetrical three-type, five-layer multilayer film (polyethylene resin / polyethylene adhesive resin / EVOH resin composition / polyethylene adhesive resin / polyethylene resin = 40 μm / 10 μm / 20 μm / 10 μm / 40 μm) was formed. It was confirmed that a good-quality multilayer film could be formed. The extruder, extrusion conditions, and die used were as follows. EVOH resin composition Extruder: Single screw extruder (Toyo Seiki Co., Ltd., Laboratory machine ME type CO-EXT) Screw: Diameter 20 mmφ, L / D 20, full-flight screw Extrusion temperature: Feeding section / compression section / metering section / die = 175 / 210 / 210 / 210°C Polyethylene adhesive resin Extruder: Single screw extruder (Technovel Co., Ltd., SZW20GT-20MG-STD) Screw: Diameter 20 mmφ, L / D 20, full-flight screw Extrusion temperature: Feeding section / compression section / metering section / die = 175 / 210 / 210 / 210°C Polyethylene resin Extruder: Single screw extruder (Plastics Technology Research Institute Co., Ltd., GT-32-A) Screw: Diameter 32 mmφ, L / D 28, full-flight screw Extrusion temperature: Feeding section / compression section / metering section / die = 175 / 210 / 210 / 210°C Die: 300mm wide, 3-type, 3-layer coat hanger die (manufactured by Plastics Technology Research Institute Co., Ltd.)

[0110] Oxygen Permeability Measurement Test Oxygen permeability was measured by the isobaric method in accordance with JIS K7126-2:2006. The measurement conditions were as follows. Low humidity conditions: Using a 100 μm thick monolayer film that had been conditioned for one month at a temperature of 20°C and a humidity of 65%, oxygen permeability was measured at a temperature of 20°C and a humidity of 65%. Apparatus: MOCON OX-TRAN2 / 21 manufactured by MOCON Corporation Humidity on oxygen supply side: 65% RH Humidity on carrier gas side: 65% RH Carrier gas flow rate: 10 mL / min Oxygen pressure: 1.0 atm Based on the oxygen permeability, the gas barrier property was evaluated according to the following criteria. A or B was determined to be good gas barrier property. The results are shown in Table 2. (Criteria) Measurement at a temperature of 20°C and a humidity of 65% A: 0.9 (cc. 20 μm / m ２ ・day・atm) B: 0.9 (cc.20μm / m ２ ・day・atm) or more 1.7 (cc.20μm / m ２ ・day・atm) C: less than 1.7 (cc.20μm / m ２ ・day・atm) or more

[0111] High humidity conditions: To evaluate the oxygen transmission rate under high humidity conditions, a 100 μm monolayer film was immersed in water at 20°C for 7 days, wet filter paper was attached to both surfaces of the film, and the oxygen transmission rate was measured under conditions of a temperature of 20°C and a humidity of 100%. Apparatus: MOCON OX-TRAN2 / 21 manufactured by MOCON Corporation Humidity on oxygen supply side: 95% RH Humidity on carrier gas side: 95% RH Carrier gas flow rate: 10 mL / min Oxygen pressure: 1.0 atm Based on the oxygen transmission rate, the gas barrier property was evaluated according to the following criteria. A or B was judged to have good gas barrier property. The results are shown in Table 2. Measurement at a temperature of 20°C and a humidity of 100% (Criteria) A: 30 (cc. 20 μm / m ２ ・day・atm) B: Less than 30 (cc.20μm / m ２ ・day・atm) or more 37 (cc.20μm / m ２ ・day・atm) C: less than 37 (cc.20μm / m ２ ・day・atm) or more 40 (cc.20μm / m ２ ・day・atm) D: Less than 40 (cc.20μm / m２ ・day・atm) or more

[0112] Evaluation of Film Cuttability (Yield Stress of Water-Containing Film) A 100 μm monolayer film was immersed in water at 23°C for 7 days, after which the water on the monolayer film surface was wiped off and the film was cut into 15 mm wide strips. A tensile test was performed using an AUTOGRAPH AGS-H (manufactured by Shimadzu Corporation) under conditions of a temperature of 23°C, humidity of 50%, a chuck distance of 30 mm, and a tensile speed of 500 mm / min. The film thickness used to calculate the yield stress was calculated using the film thickness after water immersion. The yield stress reflects the stiffness of the film when cut, and the higher the yield stress, the easier it is to cut the film. Specifically, when the film is used as a food packaging material, etc., it can be easily opened by hand through the notch. The cuttability of the film was evaluated according to the following criteria. A (yield stress of 4.6 MPa or more) or B (yield stress of 4.0 MPa or more but less than 4.6 MPa) was considered to be good cuttability. The results are shown in Table 2. (Criteria) A: 4.6 MPa or more B: 4.0 MPa or more and less than 4.6 MPa C: 3.5 MPa or more and less than 4.0 MPa D: Less than 3.5 MPa

[0113] Examples 2 to 7, 9, Comparative Examples 1 to 7 Resin compositions and the like were produced and various evaluations were carried out in the same manner as in Example 1, except that the types and blending ratios of modified EVOH (A) and EVOH (B) were changed as shown in the table, and the evaluation results are summarized in Table 2. Furthermore, using the resin compositions obtained in Examples 2 to 7, and 9, a multilayer film formation test was carried out in the same manner as in Example 1, and it was confirmed that a multilayer film in good condition could be formed in all cases.

[0114] Synthesis Example 10: 28 parts by mass of zinc acetylacetonate monohydrate was mixed with 957 parts by mass of 1,2-dimethoxyethane to obtain a mixed solution. 15 parts by mass of trifluoromethanesulfonic acid was added to the obtained mixed solution with stirring to obtain a solution containing a catalyst. That is, a solution was prepared in which 1 mole of zinc acetylacetonate monohydrate was mixed with 1 mole of trifluoromethanesulfonic acid.

[0115] A TEM-35BS extruder (37 mm diameter, L / D=52.5) ​​manufactured by Toshiba Machine Co., Ltd. was operated at an extruder temperature of 200°C and a screw rotation speed of 250 rpm. The unmodified EVOH obtained in Synthesis Example 5 (ethylene content: 38 mol%, saponification degree: >99.9 mol%, MFR: 6 g / 10 min (190°C, under a load of 2160 g)) was fed into the extruder at a rate of 11 kg / hr. The internal pressure was reduced to 60 mmHg through a vent on the inlet side of the extruder. After mixing epoxypropane (hereinafter referred to as EP) with the catalyst solution prepared by the method described above, the epoxypropane and the catalyst solution were fed into the center of the extruder at rates of 0.4 kg / hr and 0.22 kg / hr, respectively. Next, unreacted epoxypropane was removed at normal pressure from a vent on the extruder outlet side, and then an 8.2 mass% aqueous solution of trisodium ethylenediaminetetraacetate trihydrate was added as a catalyst deactivator at a rate of 0.11 kg / hr from a position immediately before the extruder outlet. The resin emerging from the extruder outlet was continuously cut to obtain modified EVOH. The resulting modified EVOH had an MFR of 6 g / 10 min (190°C, under a load of 2160 g), a modification amount with epoxypropane of 1.5 mol%, and a melting point of 160°C.

[0116] Example 8 Resin compositions and the like were produced and various evaluations were carried out in the same manner as in Example 1, except that the modified EVOH obtained in Synthesis Example 10 was used as the modified EVOH (A) and the EVOH obtained in Synthesis Example 6 was used as the EVOH (B). The evaluation results are summarized in Table 2. In addition, a multilayer film formation test was carried out in the same manner as in Example 1 using the resin composition obtained in Example 8, and it was confirmed that a multilayer film in good condition could be formed.

[0117]

[0118]

Claims

1. A resin composition containing a modified ethylene-vinyl alcohol copolymer (A) and an ethylene-vinyl alcohol copolymer (B), wherein the modified ethylene-vinyl alcohol copolymer (A) contains structural units (Ia), (Ib), and (Ic) represented by the following formulas, and the contents (mol %) a, b, and c of the structural units (Ia), (Ib), and (Ic) satisfy the following formulas (1) to (3), and the degree of saponification (DS) of the modified vinyl alcohol (A) represented by the following formula (4) is 90 mol % or more, the ethylene-vinyl alcohol copolymer (B) does not contain the structural unit (Ic), has an ethylene unit content of 33 to 54 mol %, and a degree of saponification of 80 mol % or more, and the mass ratio (A / B) of the modified ethylene-vinyl alcohol copolymer (A) to the ethylene-vinyl alcohol copolymer (B) is 30 / 70 to 95 / 5. [In the formula, a, b, and c represent the content (mol %) of each structural unit relative to 100 mol % of the total of all structural units, and W represents a hydrogen atom, a methyl group, or R ２ -OY, and X, Y, and Z each independently represent a hydrogen atom, a formyl group, or an alkanoyl group having 2 to 10 carbon atoms. １ , R ２ each independently represents a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms, and the alkylene group and the alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom. * represents a bonding site. ] 33≦a≦54 (1) 0.1≦c<3 (2) [100-(a+c)]×0.9≦b≦[100-(a+c)] (3) DS=[(total number of moles of X, Y, and Z that are hydrogen atoms) / (total number of moles of X, Y, and Z)]×100 (4) 2. The resin composition according to claim 1, wherein the mass ratio (A / B) of the modified ethylene-vinyl alcohol copolymer (A) to the ethylene-vinyl alcohol copolymer (B) is 40 / 60 to 95 / 5.

3. The resin composition according to claim 1, wherein the content (mol %) a of the structural unit (Ia) is 35 mol % or more and 44 mol % or less.

4. The resin composition according to claim 1, which has a water absorption rate of 6.5% by mass or less when immersed in water at 20°C for 2 hours.

5. The resin composition according to claim 1, wherein the content of components having a weight-average molecular weight of 200 or more but less than 1,000 is 5% by mass or less.

6. A film or sheet having a layer made of the resin composition according to any one of claims 1 to 5.

7. The film or sheet according to claim 6, further comprising a layer made of a thermoplastic resin.

8. The film or sheet according to claim 6, which has been stretched to an area ratio of 7 times or more.

9. A heat-shrinkable film or sheet comprising the film or sheet according to claim 8.

10. A co-extrusion blow-molded container comprising a layer made of the resin composition according to any one of claims 1 to 5 and a layer made of a thermoplastic resin.

11. An extrusion-molded product comprising the resin composition according to any one of claims 1 to 5.

12. A thermoformed article comprising the resin composition according to any one of claims 1 to 5.

13. A fuel container comprising the resin composition according to any one of claims 1 to 5.

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