JP2020138988A - Ethylene-vinyl alcohol copolymer resin composition - Google Patents

Abstract

To provide a film which is excellent in flexibility and bendability while maintaining gas barrier properties and adhesiveness and is also excellent in secondary processability such as stretchability and heat shrinkability.SOLUTION: A resin composition contains a specific modified ethylene-vinyl alcohol copolymer (A) and a resin (B). The resin (B) contains at least one selected from the group consisting of acid-modified polyolefin resins and acid-modified elastomers. The mass ratio [B/A] of the resin (B) to the modified ethylene-vinyl alcohol copolymer (A) is 1/99-30/70.SELECTED DRAWING: None

Description

The present invention relates to a resin composition containing a modified ethylene-vinyl alcohol copolymer and a flexible resin, and a film and a heat-shrinkable film comprising the resin composition.

Ethylene-vinyl alcohol copolymer (hereinafter, may be abbreviated as "EVOH") is excellent in transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance, etc., and by taking advantage of these characteristics, It is used in a wide range of applications such as fuel containers, including various packaging containers such as food packaging containers, pharmaceutical packaging containers, industrial chemical packaging containers, and pesticide packaging containers.

Among them, the heat-shrinkable film having a layer containing EVOH is excellent in transparency, gas barrier property, fragrance retention property, solvent resistance, oil resistance and the like. Therefore, the heat-shrinkable film is suitably used as a packaging material for foods and the like.

In recent years, there has been a demand for a heat-shrinkable film stretched at a higher magnification. In addition, since EVOH is a resin with a high elastic modulus, it does not impair the inherent transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance, etc. of EVOH as much as possible, and it has flexibility, bending resistance, and secondary. There is a demand for a resin with improved workability.

Patent Document 1 describes a modified EVOH obtained by reacting a hydroxyl group of EVOH with a monovalent epoxy compound, and the flexibility and bending resistance of EVOH are improved by blending a polyolefin resin or a compatibilizer. It is stated that.

Further, Patent Document 2 describes a modified EVOH obtained by copolymerizing 2-methylene-1,3-propanediol diacetate, and it is possible to improve the flexibility and secondary processability of EVOH. Are listed.

WO2006 / 075591 WO2014 / 024912

However, since the modified EVOH described in Patent Document 1 is obtained by reacting EVOH with an epoxy compound in a molten state, there is a problem that the number of manufacturing steps increases and the manufacturing cost increases. Further, there are cases where the gas barrier property, stretchability, heat shrinkage and the like of the film obtained by using the EVOH are insufficient.

In addition, the modified EVOH described in Patent Document 2 may have insufficient flexibility and bending resistance. In addition, when a multilayer film having a layer formed by blending a flexible resin such as an elastomer with the modified EVOH is shrunk with hot water, the interlayer adhesive force may decrease and problems such as delamination may occur.

The present invention has been made to solve the above problems, and is excellent in flexibility and bending resistance while maintaining gas barrier properties and interlayer adhesiveness in a multilayer film, and is secondary to stretchability and heat shrinkage. It is an object of the present invention to provide a resin composition having excellent processability, a film made of the resin composition, and a heat-shrinkable film.

In order to solve the above problems, the present invention provides the following resin compositions, films and heat shrink films.

［式（Ｉ）中、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、それぞれ独立に水素原子又は炭素数１〜１０のアルキル基を表し、該アルキル基は水酸基、アルコキシ基又はハロゲン原子を含んでもよい。Ｘ、Ｙ及びＺは、それぞれ独立に水素原子、ホルミル基又は炭素数２〜１０のアルカノイル基を表す。］
１８≦ａ≦５５ （１）
０．５＜ｃ≦４ （２）
［１００−（ａ＋ｃ）］×０．９≦ｂ≦［１００−（ａ＋ｃ）］ （３）
ＤＳ＝［（Ｘ、Ｙ及びＺのうち水素原子であるものの合計モル数）／（Ｘ、Ｙ及びＺの合計モル数）］×１００ （４）；
［２］ａが４０未満である、［１］の樹脂組成物；
［３］樹脂（Ｂ）中の酸変性ポリオレフィン系樹脂および酸変性エラストマーの合計含有量が１５質量％以上である、［１］または［２］の樹脂組成物；
［４］さらに、未変性またはエポキシ変性のエチレン−ビニルアルコール共重合体（Ｃ）を含む、［１］〜［３］のいずれかの樹脂組成物；
［５］ＥＶＯＨ（Ｃ）のエチレン単位含有量が４０モル％以上である、［４］の樹脂組成物；
［６］変性エチレン−ビニルアルコール共重合体（Ａ）とエチレン−ビニルアルコール共重合体（Ｃ）の合計質量に対する樹脂（Ｂ）の質量比［Ｂ／（Ａ＋Ｃ）］が１／９９以上３０／７０未満である、［４］または［５］の樹脂組成物；
［７］変性エチレン−ビニルアルコール共重合体（Ａ）に対するエチレン−ビニルアルコール共重合体（Ｃ）の質量比［Ｃ／Ａ］が５／９５〜４０／６０である、［４］〜［６］のいずれかの樹脂組成物；
［８］Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４が水素原子である、［１］〜［７］のいずれかの樹脂組成物；
［９］Ｘ、Ｙ及びＺが、それぞれ独立に水素原子又はアセチル基である、［１］〜［８］のいずれかの樹脂組成物；
［１０］［１］〜［９］のいずれかの樹脂組成物からなる層を備えるフィルム；
［１１］［１］〜［９］のいずれかの樹脂組成物からなる層を備える熱収縮フィルム；
を提供することにより達成される。 That is, the present invention
[1] Represented by the following formula (I), the contents (mol%) of a, b and c with respect to all the monomer units satisfy the following formulas (1) to (3), and the following formula (4) Contains a modified ethylene-vinyl alcohol copolymer (A) and a resin (B) having a saponification degree (DS) of 90 mol% or more, and the resin (B) is an acid-modified polyolefin resin and acid-modified. A resin composition containing at least one selected from the group consisting of elastomers and having a mass ratio [B / A] of the modified ethylene-vinyl alcohol copolymer (A) to the resin (B) of 1/99 to 30/70. ;

[In formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl group contains a hydroxyl group, an alkoxy group or a halogen atom. It may be. X, Y and Z each independently represent a hydrogen atom, a formyl group or an alkanoyl group having 2 to 10 carbon atoms. ]
18 ≤ a ≤ 55 (1)
0.5 <c ≦ 4 (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 of [1], wherein a is less than 40;
[3] The resin composition of [1] or [2], wherein the total content of the acid-modified polyolefin resin and the acid-modified elastomer in the resin (B) is 15% by mass or more;
[4] The resin composition according to any one of [1] to [3], further comprising an unmodified or epoxy-modified ethylene-vinyl alcohol copolymer (C);
[5] The resin composition of [4], wherein the ethylene unit content of EVOH (C) is 40 mol% or more;
[6] The mass ratio [B / (A + C)] of the resin (B) to the total mass of the modified ethylene-vinyl alcohol copolymer (A) and the ethylene-vinyl alcohol copolymer (C) is 1/99 or more and 30 /. The resin composition of [4] or [5], which is less than 70;
[7] The mass ratio [C / A] of the ethylene-vinyl alcohol copolymer (C) to the modified ethylene-vinyl alcohol copolymer (A) is 5/95 to 40/60, [4] to [6]. ] Any resin composition;
[8] The resin composition according to any one of [1] to [7], wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms;
[9] The resin composition according to any one of [1] to [8], wherein X, Y and Z are independently hydrogen atoms or acetyl groups, respectively;
[10] A film comprising a layer made of the resin composition according to any one of [1] to [9];
[11] A heat-shrinkable film comprising a layer made of the resin composition according to any one of [1] to [9];
Is achieved by providing.

The resin composition of the present invention is excellent in flexibility and bending resistance while maintaining gas barrier properties and interlayer adhesiveness in a multilayer film, and is also excellent in secondary processability such as stretchability and heat shrinkage. Therefore, the resin composition is preferably used for films, especially heat shrink films.

It is a schematic diagram of the structure of the extruder used for producing the epoxy-modified EVOH (C-1) in Synthesis Example 7.

<Modified ethylene-vinyl alcohol copolymer (A)>
The resin composition of the present invention is represented by the following formula (I), and the content of a, b and c (hereinafter, the content of c may be referred to as "modified amount") with respect to all the monomer units. A modified ethylene-vinyl alcohol copolymer in which (mol%) satisfies the following formulas (1) to (3) and the saponification degree (DS) defined by the following formula (4) is 90 mol% or more. A) (hereinafter sometimes abbreviated as "modified EVOH (A)") and resin (B) are included, and the mass ratio [B / A] of modified EVOH (A) and resin (B) is 1/99 to It is 30/70. This modified EVOH (A) is added to the ethylene unit shown at the left end of the following formula (I) and the vinyl alcohol-based unit having X shown in the middle of the following formula (I), and at the right end of the following formula (I). A layer formed by blending a modified EVOH (A) with a resin (B) by having a 1,3-diol-based unit having the indicated Y and Z and having a specific ratio of the 1,3-diol-based unit. It is possible to suppress a decrease in interlayer adhesive strength in a multilayer film having Further, when the modification amount is 0.5 to 4 mol%, the gas barrier property of the resin composition does not decrease and the dispersibility of the resin (B) increases, so that a high gas barrier property can be maintained even after stretching.

［式（Ｉ）中、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、それぞれ独立に水素原子又は炭素数１〜１０のアルキル基を表し、該アルキル基は水酸基、アルコキシ基又はハロゲン原子を含んでもよい。Ｘ、Ｙ及びＺは、それぞれ独立に水素原子、ホルミル基又は炭素数２〜１０のアルカノイル基を表す。］
１８≦ａ≦５５ （１）
０．５＜ｃ≦４ （２）
［１００−（ａ＋ｃ）］×０．９≦ｂ≦［１００−（ａ＋ｃ）］ （３）
ＤＳ＝［（Ｘ、Ｙ及びＺのうち水素原子であるものの合計モル数）／（Ｘ、Ｙ及びＺの合計モル数）］×１００ （４）

[In formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl group contains a hydroxyl group, an alkoxy group or a halogen atom. It may be. X, Y and Z each independently represent a hydrogen atom, a formyl group or an alkanoyl group having 2 to 10 carbon atoms. ]
18 ≤ a ≤ 55 (1)
0.5 <c ≦ 4 (2)
[100- (a + c)] × 0.9 ≦ b ≦ [100- (a + c)] (3)
DS = [(total number of moles of hydrogen atom among X, Y and Z) / (total number of moles of X, Y and Z)] × 100 (4)

In the formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ¹ , R ² , R ³ and R ⁴ may be the same group or different. The structure of the alkyl group is not particularly limited, and may have a branched structure or a cyclic structure in part. Further, the alkyl group may contain a hydroxyl group, an alkoxy group or a halogen atom. R ¹ , R ² , R ³ and R ⁴ are preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and a hydrogen atom is more preferable. Preferable examples of the alkyl group include linear or branched alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group and pentyl group. Can be mentioned.

In formula (I), X, Y and Z each independently represent a hydrogen atom, a formyl group or an alkanoyl group having 2 to 10 carbon atoms. When X, Y or Z is a hydrogen atom, the formula (I) has a hydroxyl group, and when X, Y or Z is a formyl group or an alkanoyl group, the formula (I) has an ester group. .. As the alkanoyl group, an alkanoyl group having 2 to 5 carbon atoms is preferable, and an acetyl group, a propanoyl group, a butanoyl group and the like are exemplified as suitable ones. Of these, the acetyl group is particularly suitable. It is preferable that X, Y and Z are all hydrogen atoms or a mixture containing hydrogen atoms.

The monomer unit containing X is usually obtained by saponifying a vinyl ester. Therefore, it is preferable that X is a mixture of a hydrogen atom and a formyl group or an alkanoyl group having 2 to 10 carbon atoms. Considering the availability of the monomer (vinyl acetate) and the production cost, it is particularly preferable that X is a mixture of a hydrogen atom and an acetyl group.

On the other hand, the monomer unit containing Y and Z can also be produced by copolymerizing an unsaturated monomer unit having a 1,3-diester structure and then saponifying it to form a 1,3-diol structure. It can also be produced by copolymerizing the unsaturated monomer unit having the same as it is. Therefore, both Y and Z may be only a hydrogen atom, or a mixture of a hydrogen atom and a formyl group or an alkanoyl group having 2 to 10 carbon atoms, more preferably a mixture of a hydrogen atom and an acetyl group. It may be.

In the modified EVOH (A) of the present invention, the contents (mol%) of a, b and c with respect to all the monomer units satisfy the following formulas (1) to (3).
18 ≤ a ≤ 55 (1)
0.5 <c ≦ 4 (2)
[100- (a + c)] × 0.9 ≦ b ≦ [100- (a + c)] (3)

A represents the content (mol%) of ethylene units with respect to all the monomer units, and is 18 to 55 mol%. If the ethylene unit content is less than 18 mol%, the melt moldability of the modified EVOH (A) deteriorates. The a is preferably 22 mol% or more, more preferably 25 mol% or more, still more preferably 30 mol% or more. On the other hand, when the ethylene unit content exceeds 55 mol%, the gas barrier property of the heat-shrinkable film is insufficient. The a is preferably 50 mol% or less, more preferably 45 mol% or less, still more preferably 40 mol% or less.

c represents the content (mol%) of the monomer unit containing Y and Z shown at the right end in the formula (I) with respect to all the monomer units, and is more than 0.5 mol%. It is 4 mol% or less. When c is 0.5 mol% or less, the heat shrinkability of the heat shrink film becomes insufficient. Further, when the resin (B) is blended, the interlayer adhesiveness of the multilayer film is remarkably lowered. c is preferably 0.7 mol% or more, more preferably 1.0 mol% or more, still more preferably 1.2 mol% or more. On the other hand, when c exceeds 4 mol%, the crystallinity is extremely lowered, so that the gas barrier property of the heat-shrinkable film is lowered. c is preferably 3 mol% or less.

b indicates the content (mol%) of the vinyl alcohol unit and the vinyl ester unit with respect to all the monomer units. This satisfies the following equation (3).
[100- (a + c)] × 0.9 ≦ b ≦ [100- (a + c)] (3)
That is, in the modified EVOH (A) of the present invention, 90% of the ethylene units and the monomer units other than the 1,3-diol-based unit containing Y and Z shown at the right end in the formula (I). The above is the vinyl alcohol unit or the vinyl ester unit. If the formula (3) is not satisfied, the gas barrier property becomes insufficient. The following formula (3') is preferably satisfied, and more preferably the following formula (3 ") is satisfied.
[100- (a + c)] × 0.95 ≦ b ≦ [100- (a + c)] (3')
[100- (a + c)] x 0.98 ≤ b ≤ [100- (a + c)] (3 ")

The modified EVOH (A) has a saponification degree (DS) defined by the following formula (4) of 90 mol% or more.
DS = [(total number of moles of hydrogen atom among X, Y and Z) / (total number of moles of X, Y and Z)] × 100 (4)
Here, "the total number of moles of X, Y and Z which are hydrogen atoms" indicates the number of moles of the hydroxyl group, and "the total number of moles of X, Y and Z" is the total number of moles of the hydroxyl group and the ester group. Is shown. If the degree of saponification (DS) is less than 90 mol%, not only sufficient gas barrier performance cannot be obtained, but also the thermal stability of the modified EVOH (A) becomes insufficient, and gels and lumps are likely to occur during melt molding. .. The degree of saponification (DS) is preferably 95 mol% or more, more preferably 98 mol% or more, still more preferably 99 mol% or more.

The degree of saponification (DS) can be obtained by nuclear magnetic resonance (NMR) method. The content of the monomer unit represented by a, b and c can also be obtained by the NMR method. The modified EVOH (A) is usually a random copolymer. The fact that it is a random copolymer can be confirmed from the measurement results of NMR and melting point.

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 minutes, more preferably 0.3 to 25 g / 10 minutes, and 0.5 to 20 g. / 10 minutes is more preferable. However, if the melting point is around 190 ° C or exceeds 190 ° C, measure at multiple temperatures above the melting point under a load of 2160 g, and plot the logarithm of the absolute temperature on the horizontal axis and the logarithm of MFR on the vertical axis in a semilogarithm graph. Expressed as a value extrapolated to 190 ° C.

Here, when the modified EVOH (A) is composed of a mixture of two or more different modified EVOH (A), the content, saponification degree, and MFR of the monomer units represented by a, b, and c are blended. The average value calculated from the mass ratio is used.

The method for producing the modified EVOH (A) is not particularly limited. For example, ethylene, a vinyl ester represented by the following formula (II), and a modified ethylene-vinyl ester copolymer represented by the following formula (IV) by radical polymerization of an unsaturated monomer represented by the following formula (III). After obtaining, there is a method of polymerizing it.

In formula (II), R ⁵ represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms. The alkyl group preferably has 1 to 4 carbon atoms. Examples of the vinyl ester represented by the formula (II) include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatic acid, vinyl caproate and the like. Vinyl acetate is particularly preferred from an economic point of view.

In formula (III), R ¹ , R ² , R ³ and R ⁴ are the same as in formula (I). R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 9 carbon atoms. The alkyl group preferably has 1 to 4 carbon atoms. Examples of the unsaturated monomer represented by the formula (III) include 2-methylene-1,3-propanediol diacetate, 2-methylene-1,3-propanediol dipropionate, and 2-methylene-1,3-. Examples thereof include propanediol dibutyrate. Of these, 2-methylene-1,3-propanediol diacetate is preferably used because it is easy to produce.

Wherein ^{(IV), R 1, R} 2, R 3, R 4, R 5, R 6, R 7, a, b and c are the same in formula (I) ~ (III). The modified ethylene-vinyl ester copolymer thus obtained is then saponified.

Further, instead of the unsaturated monomer represented by the formula (III), an unsaturated monomer represented by the following formula (V) may be copolymerized. In this case, the above formula is subjected to a saponification treatment. Only the unit derived from the unsaturated monomer represented by (II) will be saponified.

In formula (V), R ¹ , R ² , R ³ and R ⁴ are the same as in formula (I). Examples of the unsaturated monomer represented by the formula (V) include 2-methylene-1,3-propanediol.

Since the unsaturated monomer represented by the formulas (III) and (V) used in the present invention has a high copolymerization reactivity with the vinyl ester monomer, the copolymerization reaction easily proceeds. Therefore, the amount of modification and the degree of polymerization of the obtained modified ethylene-vinyl ester copolymer can be easily increased. Further, even if the polymerization reaction is stopped at a low polymerization rate, the amount of the unreacted unsaturated monomer remaining at the end of the polymerization is small, so that it is excellent in terms of environment and cost. In this respect, the unsaturated monomers represented by the formulas (III) and (V) have one carbon atom having a functional group at the allyl position, such as allyl glycidyl ether and 3,4-diacetoxy-1-butene. It is superior to other monomers that are only. Here, the unsaturated monomer represented by the formula (III) is more reactive than the unsaturated monomer represented by the formula (V).

A modified ethylene-vinyl ester copolymer is produced by copolymerizing ethylene, a vinyl ester represented by the formula (II), and an unsaturated monomer represented by the formula (III) or (V). The polymerization method may be any of batch polymerization, semi-batch polymerization, continuous polymerization and semi-continuous polymerization. Examples of the polymerization method include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method, and a bulk polymerization method or a solution in which the polymerization proceeds in a solvent such as no solvent or alcohol. A polymerization method is preferably used. When obtaining a modified ethylene-vinyl ester copolymer having a high degree of polymerization, the adoption of an emulsion polymerization method is one of the options.

The solvent used in the solution polymerization method is not particularly limited, but alcohol is preferably used, and for example, lower alcohols such as methanol, ethanol, and propanol are more preferably used. The amount of the solvent used in the polymerization reaction solution may be selected in consideration of the viscosity average degree of polymerization of the desired modified EVOH (A) and the chain transfer of the solvent, and the solvent contained in the reaction solution and all the monomers may be selected. The mass ratio (solvent / total monomer) of is selected from the range of 0.01 to 10, preferably from the range of 0.05 to 3.

The polymerization initiator used when copolymerizing ethylene, the vinyl ester represented by the formula (II), and the unsaturated monomer represented by the formula (III) or (V) is a known polymerization. Initiators, such as azo-based initiators, peroxide-based initiators, and redox-based initiators, are selected according to the polymerization method. Examples of the azo initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (4-methoxy-2,4). -Dimethylvaleronitrile). Examples of the peroxide-based initiator include percarbonate-based compounds such as diisopropylperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethylperoxydicarbonate; t-butylperoxyneodecanate, α. -Perester compounds such as cumylperoxyneodecanate and acetyl peroxide; acetylcyclohexylsulfonyl peroxides; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate and the like. Potassium persulfate, ammonium persulfate, hydrogen peroxide and the like may be used in combination with the initiator. The redox-based initiator is, for example, a polymerization initiator that is a combination of the above-mentioned peroxide-based initiator and a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, and longalit. The amount of the polymerization initiator used is not unconditionally determined because it differs depending on the polymerization catalyst, but it is adjusted according to the polymerization rate. The amount of the polymerization initiator used is preferably 0.01 to 0.2 mol%, more preferably 0.02 to 0.15 mol% with respect to the vinyl ester monomer. The polymerization temperature is not particularly limited, but is appropriately about room temperature to 150 ° C., preferably 40 ° C. or higher and lower than the boiling point of the solvent used.

When copolymerizing ethylene, the vinyl ester represented by the formula (II), and the unsaturated monomer represented by the formula (III) or (V), the effect of the present invention is not impaired. If so, it may be copolymerized in the presence of a chain transfer agent. Examples of the chain transfer agent 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 phosphite monohydrate. .. Of these, aldehydes and ketones are preferably used. The amount of the chain transfer agent added to the polymerization reaction solution is determined according to the chain transfer coefficient of the chain transfer agent and the degree of polymerization of the target modified ethylene-vinyl ester copolymer, but is generally determined by the vinyl ester monomer 100. 0.1 to 10 parts by mass is preferable with respect to parts by mass.

The modified ethylene-vinyl ester copolymer thus obtained can be saponified to obtain the modified EVOH (A). At this time, the vinyl ester unit in the copolymer is converted into the vinyl alcohol unit. In addition, the ester bond derived from the unsaturated monomer represented by the formula (III) is also hydrolyzed at the same time and converted into a 1,3-diol structure. In this way, different types of ester groups can be hydrolyzed at the same time by a single saponification reaction.

As a method for saponifying the modified ethylene-vinyl ester copolymer, a known method can be adopted. The saponification reaction is usually carried out in a solution of alcohol or hydrous alcohol. The alcohol preferably used at this time is a lower alcohol such as methanol or ethanol, and particularly preferably methanol. The alcohol or hydrous alcohol used in the saponification reaction may contain other solvents such as acetone, methyl acetate, ethyl acetate and benzene as long as it is 40% by mass or less by mass. The catalyst used for saponification is, for example, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methylate, or an acid catalyst such as mineral acid. The temperature at which saponification is carried out is not limited, but is preferably in the range of 20 to 120 ° C. When a gel-like product is precipitated as the saponification progresses, the product can be pulverized, washed and dried to obtain modified EVOH (A).

The modified EVOH (A) of the present invention contains ethylene, a vinyl ester represented by the above formula (II), and an unsaturated represented by the above formula (III) or (V) as long as the effects of the present invention are not impaired. It may contain structural units derived from other ethylenically unsaturated monomers that are copolymerizable with the monomer. Examples of such ethylenically unsaturated monomers include α-olefins such as propylene, n-butyl, isobutylene, and 1-hexene; allyl acid and salts thereof; and unsaturated monomers having an allyl ester group. Methacrylic acid and its salts; Unsaturated monomers having a methacrylic acid ester group; acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamide propanesulfonic acid and its salts, Acrylpropylpropyldimethylamine and its salts (eg, quaternary salts); methacrylicamide, N-methylmethacrylamide, N-ethylmethacrylicamide, methallylamide propanesulfonic acid and its salts, methacrylicamidepropyldimethylamine and its salts (eg, quaternary). Salt); methyl vinyl ether, 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-vinyloxy Vinyl ethers such as propane; vinyl cyanide such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl acetate, 2,3 -Allyl compounds such as allyloxypropane and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid and fumaric acid and salts or esters thereof; vinylsilane compounds such as vinyltrimethoxysilane; isopropenyl acetate and the like. Can be mentioned.

The content of the modified EVOH (A) in the resin composition of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. The content of modified EVOH (A) is 99% by mass or less, preferably 97% by mass or less. When the modified EVOH (A) is within the above range, a high barrier property can be maintained after stretching, and a uniform film after stretching and shrinking tends to be obtained.

The modified EVOH (A) may be used alone, or two or more modified EVOHs (A) having different ethylene unit contents, saponification degree, modification amount and the like may be used in combination.

<Resin (B)>
The resin (B) is a flexible resin containing at least one selected from the group consisting of acid-modified polyolefin-based resins and acid-modified elastomers. When the resin composition of the present invention contains the resin (B), good bending resistance can be achieved. The resin (B) used in the present invention is a resin other than EVOH, such as modified EVOH (A) and EVOH (C).

The acid-modified polyolefin-based resin is a modified olefin-based polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof to an olefin-based polymer by an addition reaction, a graft reaction, or the like. Examples of the unsaturated carboxylic acid or its anhydride include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like, but maleic anhydride is preferable. Specific acid-modified polyolefin-based resins include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymer, and maleic anhydride graft-modified ethylene-ethyl anhydride. One or a mixture of two or more selected from an acrylate copolymer, a maleic anhydride graft-modified ethylene-vinyl acetate copolymer, a maleic anhydride α-olefin copolymer polyethylene and the like can be mentioned as suitable. Of these, maleic anhydride graft-modified ethylene-propylene (block and random) copolymers, maleic anhydride graft-modified polyethylene, maleic anhydride α-olefin copolymer polyethylene, and maleic anhydride graft-modified ethylene-vinyl acetate copolymer are preferable. , Maleic anhydride graft-modified ethylene-propylene (block and random) copolymers and maleic anhydride graft-modified polyethylene are more preferred. A blend of the acid-modified polyolefin resin and an unmodified polyolefin resin compatible with the acid-modified polyolefin resin or another modified polyolefin resin may be used as the resin (B), but is particularly suitable for stretchability and gas barrier properties after stretching. From an excellent viewpoint, it is preferable that the resin (B) is composed of only an acid-modified polyolefin resin.

As the acid-modified elastomer, an acid-modified product such as a styrene-based elastomer, a polyurethane-based elastomer, a polyester-based elastomer, or a polyether-based elastomer can be used. Of these, acid-modified products of styrene-based elastomers are preferable. A blend of the acid-modified elastomer and an unmodified elastomer compatible with the acid-modified elastomer may be used as the resin (B), but the resin (B) is an acid from the viewpoint of particularly excellent stretchability and gas barrier property after stretching. It preferably consists of only a modified elastomer resin.

The resin (B) may contain an acid-modified polyolefin resin, an acid-modified elastomer, and a thermoplastic resin or thermoplastic elastomer other than EVOH. As the thermoplastic resin and the thermoplastic elastomer, an unmodified thermoplastic resin or an unmodified thermoplastic elastomer that has not been modified with a modifying group having a site capable of reacting with the modified EVOH (A) is preferable. Examples of such unmodified thermoplastic resin include polyolefin, nylon, polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, modified polyvinyl alcohol and the like. Examples of the polyolefin include polyethylene, polypropylene, poly1-butene, poly4-methyl-1-pentene, an ethylene-propylene copolymer, a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, and ethylene-vinyl. Examples thereof include ester copolymers and ethylene-acrylic acid ester copolymers. Examples of the nylon include nylon-6, nylon-66, nylon-6 / 66 copolymer and the like. Examples of the unmodified thermoplastic elastomer include styrene-based elastomers, polyurethane-based elastomers, polyester-based elastomers, and polyether-based elastomers.

The total content of the acid-modified polyolefin resin and the acid-modified elastomer in the resin (B) is preferably 15% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, and particularly preferably 50% by mass or more. , 100% by mass. When the total content of the acid-modified polyolefin resin and the acid-modified elastomer in the resin (B) is 15% by mass or more, high barrier properties can be maintained after stretching, and a uniform film tends to be obtained after stretching and shrinking. ..

The acid value of the resin (B) is preferably 15 mgKOH / g or less. When the acid value exceeds 15 mgKOH / g, the reaction point with the hydroxyl group in the modified EVOH (A) increases, a highly polymerized product is produced in the melt-kneading process, and the thermal stability tends to decrease. The acid value is more preferably 10 mgKOH / g or less, still more preferably 8 mgKOH / g or less. On the other hand, the acid value of the resin (B) is preferably 1 mgKOH / g or more. If the acid value is less than 1 mgKOH / g, the compatibility with the modified EVOH (A) is lowered, and sufficient bending resistance may not be obtained. The acid value is more preferably 2 mgKOH / g or more. The acid value of the resin (B) is measured according to JIS K 2501 using xylene as a solvent. When the resin (B) contains a thermoplastic resin other than the acid-modified polyolefin resin and the acid-modified elastomer, it means the acid value of the entire resin (B).

<Unmodified or epoxy-modified EVOH (C)>
The resin composition of the present invention may further contain unmodified or epoxy-modified EVOH (C) (hereinafter, may be abbreviated as "EVOH (C)"). When the resin composition of the present invention contains EVOH (C), it is possible to soften the film while maintaining a higher barrier property after stretching. As the EVOH (C), unmodified EVOH and epoxy-modified EVOH obtained by a known method can be used. As the epoxy-modified EVOH, for example, the epoxy-modified EVOH described in WO2003 / 072653 can be used.

The ethylene unit content of EVOH (C) is preferably 40 to 55 mol%. The saponification degree of EVOH (C) is preferably 95 mol% or more, more preferably 98 mol% or more. The MFR of EVOH (C) (at 190 ° C., under a load of 2160 g) is preferably 0.1 to 30 g / 10 minutes, more preferably 0.3 to 25 g / 10 minutes, and even more preferably 0.5 to 20 g / 10 minutes. The ethylene unit content, saponification degree and MFR of EVOH (C) are measured by the same method as that of modified EVOH (A).

When the resin composition of the present invention contains EVOH (C), EVOH (C) may be used alone or in combination of two or more.

<Mixing ratio>
The mass ratio [B / A] of the resin (B) to the modified EVOH (A) is 1/99 or more, preferably 4/96 or more, and more preferably 5/95 or more. If the mass ratio [B / A] is less than 1/99, the flexibility and bending resistance are lowered, and pinholes tend to occur at the time of bending. On the other hand, the mass ratio [B / A] is 30/70 or less, preferably 20/80 or less, more preferably 15/85 or less, and even more preferably 10/90 or less. When the mass ratio [B / A] exceeds 30/70, the gas barrier property after stretching tends to decrease.

When the resin composition of the present invention contains EVOH (C), the mass ratio [B / (A + C)] of the resin (B) to the total amount of modified EVOH (A) and EVOH (C) is preferably 1/99 or more. 4/96 or more is more preferable, and 5/95 or more is further preferable. The mass ratio [B / (A + C)] is preferably less than 30/70, more preferably 20/80 or less, further preferably 15/85 or less, and particularly preferably 10/90 or less. When the mass ratio [B / (A + C)] is in the above range, both good bending resistance and gas barrier property tend to be compatible.

When the resin composition of the present invention contains EVOH (C), the mass ratio [C / A] of EVOH (C) to modified EVOH (A) is preferably 1/99 or more, more preferably 3/97 or more, and 5 / 95 or more is more preferable, 7/93 or more is particularly preferable, and 10/90 or more is most preferable. The mass ratio [C / A] is preferably 40/60 or less, more preferably 30/70 or less, and even more preferably 20/80 or less. When the mass ratio [C / A] is in the above range, both good bending resistance and gas barrier property tend to be compatible.

<Other ingredients>
The resin composition of the present invention is, for example, a carboxylic acid compound, a phosphoric acid compound, a boron compound, a metal salt, a stabilizer, an antioxidant, an ultraviolet absorber, a plasticizer, as long as the effect of the present invention is not impaired. Contains components other than modified EVOH (A), resin (B) and EVOH (C) such as antistatic agents, lubricants, colorants, fillers, surfactants, desiccants, cross-linking agents, and reinforcing agents for various fibers. You may.

When the resin composition of the present invention contains a carboxylic acid compound, it tends to be difficult to color during melt molding. The carboxylic acid may be a monocarboxylic acid, a polyvalent carboxylic acid, or a combination thereof. Further, the carboxylic acid may be an ion, and the carboxylic acid ion may form a salt with a metal ion.

When the resin composition of the present invention contains a phosphoric acid compound, it tends to be difficult to color during melt molding. The phosphoric acid compound is not particularly limited, and various acids such as phosphoric acid and phosphorous acid and salts thereof can be used. The phosphate may be contained in any form of a first phosphate, a second phosphate, or a third phosphate, but the first phosphate is preferable. The cation species is also not particularly limited, but an alkali metal salt is preferable. Among these, sodium dihydrogen phosphate and potassium dihydrogen phosphate are preferable. When the resin composition of the present invention contains a phosphoric acid compound, the content of the phosphoric acid compound is preferably 5 to 200 ppm in terms of phosphoric acid root. When the content of the phosphoric acid compound is 5 ppm or more, the color resistance during melt molding tends to be good. On the other hand, when the content of the phosphoric acid compound is 200 ppm or less, the melt moldability tends to be good, and more preferably 160 ppm or less.

When the resin composition of the present invention contains a boron compound, it tends to be able to suppress torque fluctuations during heating and melting. The boron compound is not particularly limited, and examples thereof include boric acids, borate esters, borates, and boron hydrides. Specifically, examples of boric acids include orthoboric acid, metaboric acid, tetraboric acid and the like, examples of boric acid esters include triethyl borate, trimethyl borate and the like, and examples of borate salts include the above-mentioned various boric acids. Examples thereof include alkali metal salts of acids, alkaline earth metal salts, and boric acid. Among these compounds, orthoboric acid (hereinafter, may be simply referred to as boric acid) is preferable. When the resin composition of the present invention contains a boron compound, the content of the boron compound is preferably 20 to 2000 ppm in terms of boron element. When the content of the boron compound is 20 ppm or more, the torque fluctuation at the time of heating and melting tends to be suppressed, and more preferably 50 ppm or more. On the other hand, when the content of the boron compound is 2000 ppm or less, the moldability tends to be good, and more preferably 1000 ppm or less.

When the resin composition of the present invention contains an alkali metal salt, the interlayer adhesiveness between the resin composition layer of the present invention and another resin layer is good in a multilayer structure having a layer made of the resin composition of the present invention. It becomes a tendency to become. The cationic species of the alkali metal salt is not particularly limited, but a sodium salt or a potassium salt is preferable. The anionic species of the alkali metal salt is also not particularly limited. It can be added as a carboxylate, a carbonate, a hydrogen carbonate, a phosphate, a hydrogen phosphate, a borate, a hydroxide, or the like. When the resin composition of the present invention contains an alkali metal salt, the content of the alkali metal salt is preferably 10 to 500 ppm in terms of metal elements. The content of the alkali metal salt is more preferably 50 ppm or more. On the other hand, when the content of the alkali metal salt is 500 ppm or less, the melt stability tends to be good, and more preferably 300 ppm or less.

When the resin composition of the present invention contains an alkaline earth metal salt, deterioration of the resin and generation of deteriorated substances such as gel during repeated melt molding tend to be suppressed. The cationic species of the alkaline earth metal salt is not particularly limited, but a magnesium salt or a calcium salt is preferable. The anionic species of the alkaline earth metal salt is also not particularly limited. It can be added as a carboxylate, a carbonate, a hydrogen carbonate, a phosphate, a hydrogen phosphate, a borate, a hydroxide, or the like.

Stabilizers for improving melt stability, etc. include hydrotalcite compounds, hindered phenol-based, hindered amine-based heat stabilizers, metal salts of higher aliphatic carboxylic acids (for example, calcium stearate, magnesium stearate, etc.), etc. When the resin composition of the present invention contains a stabilizer, the content thereof is preferably 0.001 to 1% by mass.

Antioxidants include 2,5-di-t-butyl-hydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis- (6-t-butylphenol), 2,2. '-Methylene-bis- (4-methyl-6-t-butylphenol), octadecyl-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t-Butylphenol) and the like can be mentioned.

Examples of the ultraviolet absorber include ethylene-2-cyano-3', 3'-diphenylacrylate, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, and 2- (2'-hydroxy-3'-t. -Butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and the like can be mentioned.

Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, and phosphoric acid ester.

Examples of the antistatic agent include pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, carbowax and the like.

Examples of the lubricant include ethylene bisstearoamide and butyl stearate.

Examples of the colorant include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, red iron oxide and the like.

Examples of the filler include glass fiber, asbestos, ballast night, calcium silicate and the like.

<Manufacturing method of resin composition>
The method for producing the resin composition of the present invention is not particularly limited, but for example, by mixing or kneading the modified EVOH (A), the resin (B), and if necessary, EVOH (C) and other components under molten conditions. Can be manufactured. Mixing or kneading under melting conditions can be performed using a known mixing or kneading device such as a kneader ruder, extruder, mixing roll, Banbury mixer or the like. The temperature at the time of mixing or kneading may be appropriately adjusted according to the melting point of the modified EVOH (A) used, but is usually 160 ° C. or higher and 300 ° C. or lower.

<Film>
A film comprising a layer made of the resin composition of the present invention (hereinafter sometimes referred to as a "modified EVOH layer") is a preferred embodiment of the present invention. As a film molding method, any method such as extrusion molding, inflation molding, press molding, calendar molding and the like can be adopted. The thickness of the modified EVOH layer is usually 1 to 250 μm.

<Multilayer film>
The film of the present invention is a multilayer film including a layer made of a thermoplastic resin other than the modified EVOH (A) (hereinafter, may be referred to as "another thermoplastic resin layer") in addition to the modified EVOH layer. Is preferable. Examples of the thermoplastic resin used for the other thermoplastic resin layer in the multilayer film of the present invention include linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene and other polyethylenes, and ethylene-. Vinyl acetate copolymer, ionomer, ethylene-propylene (block or random) copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, polypropylene, propylene-α-olefin Polypropylenes such as copolymers, olefins such as polybutene and polypentene, or copolymers, or graft-modified with unsaturated carboxylic acids or esters thereof; polyesters; polyamides (including copolymerized polyamides); polyvinyl chlorides. Polyvinylidene chloride; acrylic resin; polystyrene; polyvinyl ester; polyester elastomer; polyurethane elastomer; chlorinated polystyrene; chlorinated polypropylene; aromatic polyketone or aliphatic polyketone, and polyalcohol obtained by reducing them; polyacetal; polycarbonate, etc. Can be mentioned. Among them, ethylene-vinyl acetate copolymer, ionomer, and polyethylene are preferably used from the viewpoint of excellent heat sealability and heat shrinkage, and polyamide is preferably used from the viewpoint of excellent mechanical strength such as puncture strength and pinhole resistance. It is preferably used.

As a configuration example of the multilayer film when polyolefin is used as the thermoplastic resin used for other thermoplastic resin layers, a polyethylene layer / adhesive resin layer / modified EVOH layer / adhesive resin layer / polyethylene layer, polypropylene layer / adhesive Layer / Modified EVOH layer / Adhesive layer / Polypropylene layer, Ionomer layer / Adhesive resin layer / Modified EVOH layer / Adhesive resin layer / Ionomer layer, Polyethylene-vinyl acetate copolymer layer / Adhesive resin layer / Modified EVOH layer / Adhesive resin layers / polyethylene-vinyl acetate copolymer layers and the like are preferable.

When polyamide is used as the thermoplastic resin used for the other thermoplastic resin layer, a configuration in which the polyamide layer and the modified EVOH layer are adjacent to each other is preferably used. With such a configuration, excellent gas barrier properties and puncture resistance can be obtained.

Assuming that the polyamide layer is N and the thermoplastic resin layer other than the modified EVOH and polyamide is T as the configuration when the polyamide layer and the modified EVOH layer are adjacent to each other, N / modified EVOH layer / T, T / N / Configurations such as modified EVOH layer / N / T, N / modified EVOH layer / N / T, and N / N / modified EVOH layer / N / T can be exemplified. N / Modified EVOH layer / Adhesive resin layer / Ethylene-vinyl acetate copolymer layer, Polyethylene layer / Adhesive resin layer / N / Modified EVOH layer / N / Adhesive resin layer / Polyethylene layer, N / Modified EVOH layer / Suitable configurations include N / adhesive resin layer / polyethylene layer, N / adhesive resin layer / N / modified EVOH layer / N / adhesive resin layer / polyethylene layer, and the like.

The multilayer film can be obtained by various manufacturing methods, and a coextrusion method, a dry laminating method, a sand laminating method, an extrusion laminating method, a coextrusion laminating method, a solution coating method, and the like can be adopted. Of these, in the coextrusion method, the resin composition containing the modified EVOH (A) and another thermoplastic resin are simultaneously extruded from an extruder, laminated in a molten state, and discharged in the form of a multilayer film from a die outlet. How to do it. When the film is formed by the coextrusion method, a method of laminating the modified EVOH layer and another thermoplastic resin layer with the adhesive resin layer interposed therebetween is preferable. As the adhesive resin, it is preferable to use a polyolefin having a carboxyl group, a carboxylic acid anhydride group or an epoxy group. Such an adhesive resin has both adhesiveness to a resin composition containing a modified EVOH (A) and adhesion to other thermoplastic resins containing no carboxyl group, carboxylic acid anhydride group or epoxy group. Are better.

Examples of the polyolefin containing a carboxyl group include polyolefins obtained by copolymerizing acrylic acid and methacrylic acid. At this time, as represented by ionomer, all or part of the carboxyl groups contained in the polyolefin may be present in the form of a metal salt. Examples of the polyolefin having a carboxylic acid anhydride group include polyolefins graft-modified with maleic anhydride and itaconic acid. Examples of the polyolefin containing an epoxy group include a polyolefin copolymerized with glycidyl methacrylate. Among these polyolefins having a carboxyl group, a carboxylic acid anhydride group, or an epoxy group, polyolefins modified with a carboxylic acid anhydride such as maleic anhydride, particularly polyethylene and polypropylene are preferable because they have excellent adhesiveness.

<Secondary processing>
The film including the layer made of the resin composition of the present invention is preferably subjected to secondary processing such as uniaxial stretching, biaxial stretching, stretch blow molding, thermoforming, and rolling. Of these, biaxial stretching is preferable. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. Examples of the stretching method include a tenter stretching method, a tubular stretching method, and a roll stretching method. The heat shrink film is a preferred embodiment of a film comprising the modified EVOH layer of the present invention. The heat-shrinkable film of the present invention is preferably stretched at a high magnification. Specifically, a heat-shrinkable film stretched to an area magnification of 7 times or more is particularly preferable. The stretching temperature is usually 50 to 130 ° C. Before the film is stretched, it may be crosslinked by irradiation or the like. From the viewpoint of further enhancing the heat shrinkage, it is preferable to cool the film immediately after stretching it.

The thickness of the modified EVOH layer in the multilayer film before stretching is preferably 3 to 250 μm, more preferably 10 to 100 μm. On the other hand, the thickness of the other thermoplastic resin layer is not particularly limited, and is appropriately selected in consideration of the required performance such as moisture permeability, heat resistance, heat sealability, transparency, and application. The thickness of the entire multilayer film before stretching is not particularly limited, but is usually 15 to 6000 μm.

<Heat shrink film>
It is preferable to use the multilayer film exhibiting heat shrinkability as the heat shrink film. The heat-shrinkable film of the present invention is excellent in adhesiveness, gas barrier property, stretchability and heat-shrinkability, and is also excellent in productivity. Therefore, it is suitably used as a material for various packaging containers such as food packaging containers, pharmaceutical packaging containers, industrial chemical packaging containers, and pesticide packaging containers.

The resin composition of the present invention can be suitably used as a material for various packaging containers such as food packaging containers, pharmaceutical packaging containers, industrial chemical packaging containers, and pesticide packaging containers, and can be particularly preferably used as heat-shrinkable packaging containers.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to this Example.

<Materials used in Examples and Comparative Examples>
・ Resin (B)
B-1: "Toughmer MP0610" (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified ethylene propylene elastomer, acid value 6.1 mg-KOH / g)
B-2: "Admer NF518" (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified polyethylene, acid value 1.4 mg-KOH / g)
B-3: "Tough Tech M1911" (manufactured by Asahi Kasei Corporation, maleic anhydride-modified hydrogenated styrene-butadiene elastomer, acid value 2.0 mg-KOH / g)
-Unmodified component of resin (B) B-4: "Toughmer P0280" (manufactured by Mitsui Chemicals, Inc., ethylene propylene elastomer)

・ EVOH (C) (manufactured by Kuraray Co., Ltd.)
C-2: "Eberle® E171" (EVOH, ethylene unit content 44 mol%, saponification degree 99.9 mol% or more, MFR (190 ° C., under 2160 g load) 1.7 g / 10 minutes)
C-3: "Eberle® H171" (EVOH, ethylene unit content 38 mol%, saponification degree 99.9 mol% or more, MFR (190 ° C., under 2160 g load) 1.7 g / 10 minutes)

<Synthesis example 1>
(1) Synthesis of Modified EVAc 100 kg of vinyl acetate (hereinafter referred to as VAac) and methanol (hereinafter referred to as MeOH) are placed in a 250 L pressure reaction tank equipped with a jacket, a stirrer, a nitrogen inlet, an ethylene inlet and an initiator addition port. (Sometimes referred to as) is charged with 10 kg and 2.9 kg of 2-methylene-1,3-propanediol diacetate (hereinafter referred to as MPDAc), the temperature is raised to 60 ° C., and then nitrogen bubbling is performed for 30 minutes in the reaction vessel. The inside was replaced with nitrogen. Next, ethylene was introduced so that the reaction vessel pressure (ethylene pressure) was 4.9 MPa. After adjusting the temperature in the reaction vessel to 60 ° C., 60 g of 2,2'-azobis (2,4-dimethylvaleronitrile) ("V-65" manufactured by Wako Pure Chemical Industries, Ltd.) was added as an initiator in a methanol solution. Was added and polymerization was initiated. During the polymerization, the ethylene pressure was maintained at 3.4 MPa and the polymerization temperature was maintained at 60 ° C. After 6 hours, when the polymerization rate of VAc reached 45%, the mixture was cooled to terminate the polymerization. After the reaction vessel was opened to deethylene, nitrogen gas was bubbled to completely deethylene. Then, after removing the unreacted VAc under reduced pressure, MeOH was added to a modified ethylene-vinyl acetate copolymer (sometimes referred to as modified EVAc in the present specification) into which a structural unit derived from MPDAc was introduced by copolymerization. It was added to make a 20 mass% MeOH solution.

(2) Kenning of Modified EVAc A 20% by mass MeOH solution of 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 was raised to 60 ° C. while blowing nitrogen into this solution, and 0.5 equivalent amount of sodium hydroxide was added as a 2N MeOH solution to the vinyl acetate unit in the modified EVAc. After the addition of the sodium hydroxide MeOH solution was completed, the saponification reaction was allowed to proceed by stirring for 2 hours while maintaining the in-system temperature at 60 ° C. After that, acetic acid was added to stop the saponification reaction. Then, ion-exchanged water was added while heating and stirring at 60 to 80 ° C., MeOH was distilled out of the reaction vessel, and modified EVOH was precipitated. The precipitated modified EVOH was collected and pulverized with a mixer. The obtained modified EVOH powder was put into a 1 g / L acetic acid aqueous solution (bath ratio 20: ratio of 20 L of aqueous solution to 1 kg of powder) and washed by stirring for 2 hours. This was deliquesed, further added to a 1 g / L acetic acid aqueous solution (bath ratio 20), and stirred and washed for 2 hours. The deflated product was put into ion-exchanged water (bath ratio 20), stirred and washed for 2 hours, and the operation of deflating the liquid was repeated 3 times for purification. Next, the crude EVOH was crudely dried by immersing it in 10 L of an aqueous solution containing 0.5 g / L of acetic acid and 0.1 g / L of sodium acetate with stirring for 4 hours, then removing the liquid, and drying this at 60 ° C. for 16 hours. Got

(3) Production of Modified EVOH Hydrous Pellet A crude dried product of modified EVOH, water, and MeOH obtained in (2) were charged in an 80 L stirring tank equipped with a jacket, a stirrer, and a reflux condenser, and the temperature was raised to 80 ° C. It was dissolved. This solution is extruded into a mixed solution of water / MeOH = 90/10 cooled to 5 ° C. through a tube having a diameter of 4 mm to precipitate in the form of strands, and the strands are cut into pellets with a strand cutter to obtain modified EVOH. Hydrous pellets were obtained. The water content of the obtained modified EVOH water-containing pellets was measured with a halogen moisture meter "HR73" manufactured by METTLER, and found to be 60% by mass.

(4) Production of Modified EVOH Pellet The hydrous pellet of modified EVOH obtained in (3) above was put into a 1 g / L acetic acid aqueous solution (bath ratio 20) and washed with stirring for 2 hours. This was deliquesed, further added to a 1 g / L acetic acid aqueous solution (bath ratio 20), and stirred and washed for 2 hours. After the liquid was removed, the acetic acid aqueous solution was updated and the same operation was performed. After washing with an aqueous acetic acid solution, the solution is poured into ion-exchanged water (bath ratio 20), stirred and washed for 2 hours, and the operation of removing the solution is repeated 3 times to purify the catalyst during the saponification reaction. Hydrous pellets of modified EVOH from which the residue was removed were obtained. The hydrous pellet is put into an aqueous solution (bath ratio 20) having a sodium acetate concentration of 0.5 g / L, an acetic acid concentration of 0.8 g / L, and a phosphoric acid concentration of 0.005 g / L, and is immersed for 4 hours with regular stirring. It was. This was deflated and dried at 80 ° C. for 3 hours and at 105 ° C. for 16 hours to obtain modified EVOH pellets.

(5) Content of each structural unit of modified EVOH and degree of saponification The content of ethylene units in the modified EVAc (a mol% in formula (IV)) and the content of structural units derived from vinyl acetate (formula (IV)). The content of structural units derived from MPDAc (c mol% in formula (IV)) was calculated by measuring ¹ H-NMR of modified EVAc before saponification.

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

Each peak in the spectrum is assigned as follows.
-0.6 to 1.0 ppm: Methylene proton (4H) in ethylene units at the terminal site
1.0 to 1.85 ppm: Methylene proton (4H) as an intermediate site ethylene unit, main chain site methylene proton (2H) as a structural unit derived from MPDAc, methylene proton as a vinyl acetate unit (2H)
1.85-2.1ppm: Methyl proton (6H), which is a structural unit derived from MPDAc, and methyl proton (3H), which is a vinyl acetate unit.
3.7-4.1 ppm: Side chain site methylene proton (4H) of the structural unit derived from MPDAc
4.4-5.3 ppm: Methine proton (1H) in vinyl acetate units

According to the above attribution, the integral value of 0.6 to 1.0 ppm is x, the integral value of 1.0 to 1.85 ppm is y, and the integral value of 3.7-4.1 ppm is z, 4.4-5. When the integral value of 3 ppm is 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 , Each is calculated according to the following formula.
a = (2x + 2y-z-4w) / (2x + 2y + z + 4w) x 100
b = 8w / (2x + 2y + z + 4w) x 100
c = 2z / (2x + 2y + z + 4w) x 100
As a result of calculation by the above method, the content of ethylene unit (a) is 38.0 mol%, the content of vinyl ester unit (b) is 60.5 mol%, and the content of structural unit derived from MPDAc (c) is. It 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 the saponification treatment.

(6) Degree of saponification of modified EVOH ¹ H-NMR measurement was similarly carried out for the modified EVOH after saponification. The crude dried product of the modified EVOH obtained in the above (2), tetramethylsilane as an internal standard material was dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetrafluoro acid (TFA) as an additive, 500 MHz The ¹ H -Measurement was performed at 80 ° C. using NMR (manufactured by Nippon Denshi Co., Ltd .: "GX-500"). The degree of saponification was calculated from the peak intensity ratio of methyl proton (1.85 to 2.1 ppm) in vinyl acetate unit and methine proton (3.15 to 4.15 ppm) in vinyl alcohol unit. The degree of saponification of the modified EVOH was 99.9 mol% or more.

(7) Sodium salt content and phosphoric acid compound content in the modified EVOH pellets 0.5 g of the modified EVOH pellets obtained in (4) above was placed in a Teflon® pressure vessel, and 5 mL of concentrated nitric acid was added thereto. In addition, it was decomposed at room temperature for 30 minutes. After 30 minutes, the lid was closed, and the mixture was decomposed by heating at 150 ° C. for 10 minutes and then at 180 ° C. for 5 minutes using a wet decomposition device (manufactured by Actac Co., Ltd .: “MWS-2”), and then cooled to room temperature. This treatment liquid was transferred to a 50 mL volumetric flask (manufactured by TPX) and measured with pure water. The contained metal of this solution was analyzed by an ICP emission spectroscopic analyzer (“OPTIMA4300DV” manufactured by PerkinElmer Co., Ltd.), and the contents of sodium element and phosphorus element were determined. The sodium salt content was 150 ppm in terms of sodium element, and the phosphate compound content was 10 ppm in terms of phosphate root.

(8) MFR of modified EVOH
For the modified EVOH pellet obtained in (4) above, the MFR was measured at a temperature of 190 ° C. and a load of 2160 g in accordance with JIS K 7210 (1999). The MFR was 1.8 g / 10 minutes.

<Synthesis Examples 2-6>
Modified EVOH pellets were produced and evaluated in the same manner as in Synthesis Example 1 except that the polymerization conditions were changed to those shown in Table 1. The results are shown in Table 1.

<Synthesis example 7>
Ethylene content 44 mol%, saponification degree 99.8%, intrinsic viscosity 0.096 L / g, MFR 5 g / 10 minutes (190 ° C, under 2160 g load) EVOH {acetic acid content 53 ppm, sodium content 1 ppm (metal element) (Conversion), potassium content 8 ppm (metal element conversion), phosphoric acid compound content 20 ppm (phosphoric acid root conversion value)}, 5 kg of pellets were placed in a polyethylene bag. Then, 27.44 g (0.125 mol) of zinc acetate dihydrate and 15 g (0.1 mol) of trifluoromethanesulfonic acid were dissolved in 500 g of water to prepare an aqueous solution, and the aqueous solution was added to EVOH in the bag. .. The EVOH to which the catalyst solution was added as described above was heated at 90 ° C. for 5 hours with the mouth of the bag closed while shaking occasionally, and the EVOH was impregnated with the catalyst solution. The obtained EVOH was vacuum dried at 90 ° C. to obtain a catalyst-containing EVOH.

10 parts by mass of the catalyst-containing EVOH, ethylene content 44 mol%, saponification degree 99.8%, MFR = 5 g / 10 minutes (190 ° C. under a load of 2160 g) EVOH {acetic acid content 53 ppm, sodium content 1 ppm ( TEM-35BS extruder manufactured by Toshiba Machine Co., Ltd. (37 mmφ) using a dry blend of 90 parts by weight of EVOH with a potassium content of 8 ppm (metal element equivalent) and a phosphoric acid compound content of 20 ppm (phosphoric acid root equivalent)}. , L / D = 52.5) was used to synthesize epoxy propane-modified EVOH. First, as shown in FIG. 1, a screw configuration, a vent, and a pressure inlet were installed. The barrel C1 was water-cooled, the barrels C2 to C3 were set to 200 ° C., the barrels C4 to C15 were set to 220 ° C., and the operation was performed at a screw rotation speed of 200 rpm. From the resin feed port of C1, the above EVOH containing a catalyst composed of a dry-blended mixture was fed at a ratio of 11 kg / hr, the vent 1 was depressurized to an internal pressure of 60 mmHg, and epoxy propane was supplied from the inlet 1 of C8. Feeded at a rate of 5 kg / hr (pressure at the time of feeding: 3.5 MPa). Vent 2 was depressurized to an internal pressure of 200 mmHg, unreacted epoxy propane was removed, and an 8.2 wt% aqueous solution of ethylenediaminetetraacetic acid trisodium trihydrate trihydrate was added at a rate of 0.14 kg / hr from the inlet 2 of C13. ..

Vent 3 was depressurized to an internal pressure of 20 mmHg to remove water to obtain epoxy-modified EVOH (C-1). The saponification degree of the epoxy-modified EVOH (C-1) was 99.8 mol%, the MFR was 5 g / 10 minutes (under a load of 190 ° C. and 2160 g), and the melting point was 109 ° C. The zinc ion content is 150 ppm (2.3 μmol / g), and the alkali metal salt content is 168 ppm (7.1 μmol / g) in terms of metal elements [sodium: 160 ppm (6.9 μmol / g), potassium: 8 ppm (0.2 μmol / g)], and the content of trifluoromethanesulfonate ion was 270 ppm (1.8 μmol / g). The content of alkali metal ions was 3.9 times (molar ratio) the content of trifluoromethanesulfonic acid ions.

<Evaluation method>
(A) Stretching test The 150 μm-thick single-layer film obtained in Examples and Comparative Examples is subjected to a biaxial stretching apparatus manufactured by Eto'o Co., Ltd., and simultaneous biaxial stretching is performed at 80 ° C. at a stretching ratio of 3 × 3 times. Obtained a heat-shrinkable film. The heat-shrinkable film obtained by stretching at a stretching ratio of 3 × 3 times was evaluated according to the following criteria.
Judgment: Criterion A: No uneven stretching or local uneven thickness was observed, and the appearance was good.
B: Uneven stretching or local uneven thickness occurred.
C: The film broke.

(B) Shrink test The heat-shrinkable film having a draw ratio of 3 × 3 obtained in (a) above was cut into 10 cm × 10 cm, immersed in hot water at 80 ° C. for 10 seconds, and the shrink ratio (%) was as follows. Calculated in.
Shrink rate (%) = {(S-s) / S} x 100
S: Area of film before shrink s: Area of film after shrink

(C) Flexibility test After adjusting the humidity of the 20 μm-thick single-layer film obtained in Examples and Comparative Examples under the conditions of 23 ° C./50% RH, a gelboflex tester manufactured by Rigaku Kogyo Co., Ltd. was used. It was used and the flexibility was measured. First, a 12-inch x 8-inch film was rolled up and fastened with a ring to form a cylinder with a diameter of 3.5 inches. According to ASTM F392, both ends are gripped with an initial grip spacing of 7 inches, a grip spacing of 1 inch at maximum flexion, a twist of 440 degrees at the first 3.5 inches of stroke, and then 2.5 inches straight and horizontal. A reciprocating motion consisting of repeated motions, which is an exercise, was performed at a speed of 40 times / minute. The pinhole after bending 500 times was evaluated.

(D) Measurement of Young's modulus A 150 μm-thick single-layer film obtained in Examples and Comparative Examples was subjected to humidity control for 3 days under the conditions of 23 ° C. and 50% RH as a sample, and according to ASTM D-638. Then, the Young's modulus in the MD direction (film extrusion direction) was measured by an autograph (“AGS-H” manufactured by Shimadzu Corporation) under the condition of a tensile speed of 5 mm / min, and used as an index of flexibility. The measurement was performed on each of 10 samples, and the average value was calculated.

(E) Appearance Evaluation after Shrinkage The multilayer heat-shrinkable films obtained in Examples and Comparative Examples were cut into 10 cm × 10 cm, immersed in hot water at 80 ° C. for 60 seconds, and the shrunk film was visually inspected as described below. Evaluated by criteria.
A: It shrank uniformly without causing delamination.
B: No delamination occurred, but it shrank unevenly.
C: Delamination occurred.

(F) Oxygen Permeation Rate Measurement The multilayer film obtained in Examples and Comparative Examples and the stretched multilayer film (heat shrink film) are humidity-controlled for 7 days at 20 ° C. and 65% RH, and then under the same conditions. The oxygen permeation rate was measured (“OX-TORAN MODEL 2/21” manufactured by Mocon).

<Example 1>
97 parts by mass of the modified EVOH pellet obtained in Synthesis Example 1 as the modified EVOH (A) and 3 parts by mass of the B-1 as the resin (B) are dry-blended and then melted by a twin-screw extruder. After kneading, pelletization was performed to prepare resin composition pellets. Using the obtained resin composition pellets, a single-layer film and a multilayer film were prepared under the following conditions.
(Single-layer film production conditions)
Made of single layer under the following conditions using a 20 mm extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. The film was formed to obtain a single-layer film.
(Extrusion conditions)
Cylinder temperature: Supply unit 175 ° C, compression unit 210 ° C, measuring unit 210 ° C
Die temperature: 210 ° C
Screw rotation speed: 40-100 rpm
Discharge rate: 0.4 to 1.5 kg / hour Pick-up roll temperature: 80 ° C
Pick-up roll speed: 0.8 to 3.2 m / min Film thickness: 20 to 150 μm

(Multilayer film production conditions)
A multilayer film [layer structure: EVA layer / adhesive resin layer / resin composition layer / adhesive resin layer / EVA layer, thickness (μm): 100/15/15/15/100] was prepared under the following conditions. ..
(Resin used)
EVA layer: "Evaflex EV340" (manufactured by Mitsui DuPont Polychemical Co., Ltd., polyethylene vinyl acetate resin)
Adhesive resin layer: "Admer VF500" (manufactured by Mitsui Chemicals, Inc., acid-modified polyethylene vinyl acetate resin)
Resin composition layer: Obtained resin composition pellets (coextrusion conditions)
Extrusion temperature of each resin: Supply part / compression part / measurement part / die = 170 ℃ / 210 ℃ / 210 ℃ / 210 ℃
Extruder for EVA: 32φ extruder GT-32-A type (manufactured by Plastic Engineering Laboratory Co., Ltd.)
Extruder for adhesive resin: 25φ extruder P25-18-AC type (manufactured by Osaka Seiki Kogyo Co., Ltd.)
Extruder for resin composition: 20φ extruder Lab machine ME type CO-EXT (manufactured by Toyo Seiki Co., Ltd.)
T-die: 300 mm width for 3 types and 5 layers (manufactured by Plastic Engineering Laboratory Co., Ltd.)
Cooling roll temperature: 50 ° C
Pick-up speed: 4m / min

Using the obtained multilayer film, preheating was performed at 80 ° C. for 30 seconds with a biaxial stretching apparatus manufactured by Eto'o Co., Ltd., and then simultaneous biaxial stretching was performed at a stretching ratio of 3 × 3 to obtain a heat-shrinkable film.

Using the obtained single-layer film, multilayer film, and heat-shrinkable film, evaluation was performed according to the above evaluation methods (a) to (f). The evaluation results are shown in Table 2.

<Examples 2 to 15, Comparative Examples 1 to 7>
Single-layer film, multilayer film and heat-shrinkable film in the same manner as in Example 1 except that the types and amounts of modified EVOH (A), resin (B) and EVOH (C) were changed as shown in Table 1. Was prepared and evaluated. The evaluation results are shown in Table 2.

When the content of c (the unit shown at the right end of the following formula (I)) is more than 0.5 mol% and 4 mol% or less (Examples 1 to 15), and when the content of c is small (Comparative Example 1). ), The delamination of the multilayer film after shrinking was improved. It is presumed that this is because c improves the adhesiveness between the resin composition of the present invention and the adhesive resin, and the hot water resistance is improved. As shown in Examples 3, 7 to 9, the higher the content of the acid-modified polyolefin resin or acid-modified elastomer in the resin (B), the better all the performances were. It is considered that the larger the content of the acid-modified polyolefin resin or the acid-modified elastomer, the finer the resin (B) is dispersed in EVOH, and the more uniformly the film is stretched. Therefore, it is considered that the continuous phase due to the resin (B) is not formed after stretching, and the deterioration of the barrier property is suppressed. It is considered that the ethylene unit content of unmodified or epoxy-modified EVOH (C) is preferably 40 mol% or more. By blending EVOH (C) having a high ethylene content as shown in Examples 10 and 11, the film was softened and the deterioration of oxygen barrier property after stretching was suppressed. It is presumed that this is because the compatibility of the resin (B) is enhanced and the resin (B) is finely dispersed in the EVOH.

Claims (11)

It is represented by the following formula (I), and the contents (mol%) of a, b and c with respect to all the monomer units satisfy the following formulas (1) to (3) and are defined by the following formula (4). It contains a modified ethylene-vinyl alcohol copolymer (A) having a saponification degree (DS) of 90 mol% or more and a resin (B), and the resin (B) is composed of an acid-modified polyolefin resin and an acid-modified elastomer. A resin composition containing at least one selected from the group and having a mass ratio [B / A] of the modified ethylene-vinyl alcohol copolymer (A) to the resin (B) of 1/99 to 30/70.

[In formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl group contains a hydroxyl group, an alkoxy group or a halogen atom. It may be. X, Y and Z each independently represent a hydrogen atom, a formyl group or an alkanoyl group having 2 to 10 carbon atoms. ]
18 ≤ a ≤ 55 (1)
0.5 <c ≦ 4 (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) The resin composition according to claim 1, wherein a is less than 40. The resin composition according to claim 1 or 2, wherein the total content of the acid-modified polyolefin resin and the acid-modified elastomer in the resin (B) is 15% by mass or more. The resin composition according to any one of claims 1 to 3, further comprising an unmodified or epoxy-modified ethylene-vinyl alcohol copolymer (C). The resin composition according to claim 4, wherein the ethylene-vinyl alcohol copolymer (C) has an ethylene unit content of 40 mol% or more. The mass ratio [B / (A + C)] of the resin (B) to the total mass of the modified ethylene-vinyl alcohol copolymer (A) and the ethylene-vinyl alcohol copolymer (C) is 1/99 or more and less than 30/70. The resin composition according to claim 4 or 5. Any of claims 4 to 6, wherein the mass ratio [C / A] of the ethylene-vinyl alcohol copolymer (C) to the modified ethylene-vinyl alcohol copolymer (A) is 5/95 to 40/60. The resin composition described. The resin composition according to any one of claims 1 to 7, wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms. The resin composition according to any one of claims 1 to 8, wherein X, Y and Z are independently hydrogen atoms or acetyl groups. A film comprising a layer made of the resin composition according to any one of claims 1 to 9. A heat-shrinkable film comprising a layer made of the resin composition according to any one of claims 1 to 9.

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