JP4832783B2 - Gas barrier material composed of a novel ethylene-vinyl alcohol copolymer - Google Patents

Description

  The present invention relates to a novel ethylene-vinyl alcohol copolymer, and more particularly to an ethylene-vinyl alcohol copolymer having a fluorine-containing group at a terminal. The present invention also relates to a novel ethylene-vinyl alcohol copolymer resin composition, and more particularly to an ethylene-vinyl alcohol copolymer resin composition having improved gas barrier humidity dependency and water vapor barrier property.

  An ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is a thermoplastic resin having excellent gas barrier properties, and is widely used as various packaging materials such as films, sheets, and containers by taking advantage of the gas barrier properties. ing. However, since the gas barrier property is highly dependent on humidity, and particularly under high humidity, the gas barrier property is greatly reduced, so that there is a problem that the gas barrier property is insufficient depending on the contents to be packaged. Further, EVOH has a low barrier property against water vapor, and there is a problem that it cannot be used in applications requiring such performance.

  On the other hand, various methods have been proposed to improve the gas barrier property and water vapor barrier property of EVOH under high humidity. For example, copolymerizing a hydrophobic monomer with EVOH, mixing an inorganic layered compound or an inorganic oxide with EVOH, or introducing a hydrophobic functional group into EVOH.

  However, generally, when a hydrophobic monomer is copolymerized with EVOH, the water resistance is improved, but the barrier property tends to be lowered. In addition, when an inorganic layered compound or an inorganic oxide is mixed, the molding process becomes complicated and the moldability tends to decrease, so the molding conditions are limited, or the inorganic compound mixed in when recovered or discarded. There are problems such as needing attention.

  When a hydrophobic functional group is introduced at the end of EVOH, there is no problem as in the case of mixing an inorganic compound, and it is possible to suppress a decrease in barrier properties as compared with copolymerizing a hydrophobic monomer. As such a method, Patent Document 3 has an RS group at the end (where R is a hydrocarbon group having 4 to 30 carbon atoms, S represents a sulfur atom), an ethylene content of 20 to 60 mol%, and acetic acid. A saponified ethylene-vinyl acetate copolymer having a vinyl unit saponification degree of 80% or more and a number average polymerization degree of 10 to 1,000 is disclosed in Patent Document 4 as an RS group (where R is a carbon number of 1 to 18). Or an hydroxyl group-containing hydrocarbon group, S is a sulfur atom) and an EVOH resin composition comprising the same and conventional EVOH.

  However, in the modified EVOH of Patent Documents 3 and 4, the degree of modification that does not impair the original barrier property of EVOH is sufficient for the humidity dependency and the water vapor barrier property of the gas barrier property that are the objects of the present invention. There was no level.

  On the other hand, as an example of terminal modification of a polyvinyl alcohol-based resin, modified polyvinyl alcohol with a fluorine-containing group is known. For example, Patent Documents 1 and 2 describe a method for producing a polyvinyl ester polymer having a fluorine-containing group at the terminal and a polyvinyl alcohol polymer. However, this polyvinyl alcohol-based polymer is premised on use as an aqueous solution, and there is no description regarding gas barrier properties.

Japanese Patent Laid-Open No. 60-1208 JP-A-10-34844 JP-A-63-301206 JP-A-10-251345

  An object of the present invention is to provide a novel ethylene-vinyl alcohol copolymer and an ethylene-vinyl alcohol copolymer resin having excellent gas barrier properties, small humidity dependency of gas barrier properties, and excellent water vapor barrier properties It is to provide a composition.

As a result of intensive studies aimed at achieving the above-mentioned problems, the present inventors have found that by introducing a fluorine-containing group at the end of EVOH, gas barrier properties under high humidity and water vapor barrier properties are remarkably improved. The present invention has been completed. That is, the present invention is a gas barrier material comprising an ethylene-vinyl alcohol copolymer (B) having an ethylene content of 20 to 60 mol%, a saponification degree of 90 mol% or more, and having a fluorine-containing group at the terminal. Another invention of the present invention is an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more, and an ethylene-vinyl having a fluorine-containing group at the above-mentioned terminal. It is a gas barrier material which consists of an alcohol copolymer (B), and consists of an ethylene-vinyl alcohol copolymer resin composition whose (A) / (B) is 99 / 1-50 / 50 (weight ratio).

  The ethylene-vinyl alcohol copolymer having a fluorine-containing group at the terminal of the present invention (hereinafter sometimes referred to as the modified EVOH of the present invention) and the EVOH resin composition containing the copolymer have a small gas barrier humidity dependency. Therefore, when used as various packaging materials such as sheets, films, and containers, good barrier properties can be obtained regardless of the type of contents. Moreover, since it is excellent in water vapor | steam barrier property compared with conventional EVOH, the application to the use as which water vapor | steam barrier property was conventionally required which EVOH could not be used is possible.

  First, the novel ethylene-vinyl alcohol copolymer which is the first invention of the present invention will be described.

  The ethylene content of the modified EVOH of the present invention is 20 to 60 mol%, preferably 22 to 55 mol%, more preferably 24 to 50 mol%. An ethylene content of less than 20 mol% is not preferable because the thermal stability of EVOH is reduced. When the ethylene content exceeds 60 mol%, the gas barrier property is lowered, which is not preferable.

  The degree of saponification of the modified EVOH of the present invention is 90 mol% or more, preferably 95 mol% or more, more preferably 98 mol% or more, and further preferably 99 mol% or more. If the degree of saponification is less than 90 mol%, not only the gas barrier property is lowered but also the thermal stability of the modified EVOH is lowered, which is not preferable.

  The modified EVOH of the present invention must have a fluorine-containing group at the terminal. When EVOH has a fluorine-containing group at its terminal, excellent performances such as a gas barrier property that is the object of the present invention having a small humidity dependency and an excellent water vapor barrier property are exhibited. Below, the fluorine-containing group which terminal modification EVOH of the present invention has is explained.

  There are no particular restrictions on the fluorine-containing group, and various types are available from the viewpoints of the molecular weight, ethylene content, degree of saponification, required gas barrier properties and water vapor barrier properties, and ease of production of modified EVOH. Can be selected.

  Among such fluorine-containing groups, the main chain length is preferably 3 or more, more preferably 5 or more, from the viewpoint of maintaining gas barrier properties and water vapor barrier properties under high humidity. On the other hand, from the viewpoint of maintaining the gas barrier properties inherent to EVOH, the main chain length is preferably 30 or less, and more preferably 20 or less. The main chain length as used herein refers to the number of hydrogen and fluorine atoms contained in the fluorine-containing group in order from the atom connecting the ethylene unit or vinyl alcohol unit of the EVOH main chain along the bond chain. Points to the largest of

  Furthermore, in the present invention, when the fluorine-containing group contains fluorine, the gas barrier property and water vapor barrier property under high humidity are remarkably improved. From such a viewpoint, the proportion of fluorine atoms contained in the fluorine-containing group is preferably 30% by weight or more, and more preferably 50% by weight or more.

As such a fluorine-containing group, for example, the general formula (I)
R _f -X _m- (I)
(Where m is 0 or 1).

In the above general formula (I), R _f is a fluorinated alkyl group or alkyl ether group, and examples thereof include the general formula A- (CF ₂ ) _q-
(Wherein A represents a hydrogen atom, a fluorine atom, (CF ₃ ) ₂ CH— or (CF ₃ ) ₂ CF—, q represents an integer of 2 to 20), or formula _{(CF 3) 2 CF-O-} (CF 2) q -
(Wherein q represents an integer of 2 to 20)
Or the general formula _{(CF 3)} 2 CF-O- _{[CF (CF} 3) _-CF 2 -O] _t -CF _(CF 3) -
(Wherein, t represents an integer of 1 to 10).

Examples of _{R f, H- (CF 2)} 2 -, H- (CF 2) 4 -, H- (CF 2) 6 -, H- (CF 2) 8 -, F (CF 2) 2 _{-, F (CF 2) 3} -, F- (CF 2) 4 -, F- (CF 2) 5 -, F- (CF 2) 6 -, F- (CF 2) 7 -, F- (CF _{2) 8 -, F- (CF} 2) 9 -, F- (CF 2) 10 -, (CF 3) 2 CF- (CF 2) 2 -, (CF 3) 2 CF- (CF 2) 4 - , (CF ₃ ) ₂ CF— (CF ₂ ) ₆ —, (CF ₃ ) ₂ CF— (CF ₂ ) ₈ —, (CF ₃ ) ₂ CF—O— (CF ₂ ) ₂ —, (CF ₃ ) _{2 CF-O- (CF 2) 12} -, (CF 3) 2 CF - O- (CF 2) 13 -, (CF 3) 2 CH- (CF 2) 2 -, (CF 3) 2 CF O- _{[CF (CF} 3) _-CF 2 -O] ₃ -CF (CF ₃₎ -, and the like, but not limited thereto.

In the general formula (I), X is a general formula — (CH ₂ ) _n —.
(N is an integer from 1 to 5)
An alkylene group represented by
_{- (CH 2) p -O- (} CH 2) n -
An alkylene ether group represented by (p and n are each an integer of 1 to 5),
-CONH- _{(CH 2) n} -
An alkyleneamide group represented by (n is an integer of 1 to 5),
_{- (S) r - (CH} 2) p -Q- (CH 2) n -
(P and n are each an integer of 1 to 5, Q is a sulfur atom or an oxygen atom, r is 0 or 1 when Q is a sulfur atom, and 1 when Q is an oxygen atom) ,
^{_{- (CH 2) p -NR 1}} - (CH 2) n -
^{(R 1} is an alkyl group having 1 to 5 carbon atoms, p and n are each an integer of 1 to 5) alkyleneimino group represented by,
_{- (CH 2) p -COO- (} CH 2) n -
Or -COO- _{(CH 2) n} -
(P and n are each an integer of 1 to 5), or —CH ₂ —CR ² (OH) —CHR ³ —
Or —CH ₂ —CR ² (CHR ³ OH) —
A hydroxyl group-containing alkylene group represented by (R ² and R ³ are each a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) can be exemplified.

Examples of X include —CH ₂ —O— (CH ₂ ) ₃ —, — (CH ₂ ) ₂ —, — (CH ₂ ) ₄ —, —S— (CH ₂ ) ₂ —, — (CH ₂ ) ₂ -S- (CH ₂ ) _3- , -S- (CH ₂ ) ₂ -O- (CH ₂ ) _2- , -S- (CH ₂ ) ₂ -S- (CH ₂ ) _2- , -CONH _{- (CH 2) 2 -,} - (CH 2) 2 -COO- (CH 2) 3 -, - COO- (CH 2) 3 -, - CH 2 -CH (OH) -CH 2 -, - CH 2 -CH _(CH 2 OH) - but the like, not limited thereto.

Among these, H— (CF ₂ ) ₄ —CH ₂ O (CH ₂ ) ₃ —, H— (CF ₂ ) ₆ —, from the viewpoints described above and the viewpoint of ease of synthesis described below. _{CH 2 O (CH 2) 3} -, H- (CF 2) 8 -CH 2 O (CH 2) 3 -, F- (CF 2) 7 -CH 2 O (CH 2) 3 -, F- (CF _{2) 9 -CH 2 O (CH} 2) 3 -, F- (CF 2) 10 -CH 2 O (CH 2) 3 -, (CF 3) 2 CF (CF 2) 4 - (CH 2) 2 O (CH ₂ ) ₃ —, F— (CF ₂ ) ₉ —CONH— (CH ₂ ) ₂ — and the like are preferably used.

  It is not clear at this time whether such fluorine-containing groups, and further fluorine-containing groups satisfying certain conditions, are particularly effective in improving gas barrier properties and water vapor barrier properties under high humidity. The reason can be considered.

  When gas passes through a crystalline polymer such as EVOH, it is considered that gas molecules cannot pass through the EVOH crystal part, but pass through the amorphous part. On the other hand, theoretically, the gas permeation rate (P) is expressed by P = S × D by the diffusion rate (D) of gas molecules in the barrier material and the solubility (S) of the gas molecules in the barrier material. Regarding the phenomenon of gas permeating through EVOH, it is considered that the free volume generated as a result of molecular motion derived from the molecular structure of EVOH affects the diffusion rate, and the affinity between EVOH and gas molecules affects the solubility. From this, the phenomenon that the gas barrier property is highly dependent on humidity or has a low water vapor barrier property, which has been a problem with conventional EVOH, can be considered as follows.

  That is, EVOH has many hydrophilic hydroxyl groups in the molecule, and water (vapor) molecules have high solubility, so the water vapor transmission rate is large due to the influence of the solubility term (low water vapor barrier property). Become. In addition, since water molecules that have penetrated into EVOH under high humidity interact with hydroxyl groups contained in EVOH, the molecular motion of the amorphous part increases and free volume increases. Also for gas, the permeation rate increases (barrier property decreases). Therefore, in any case, the high hydrophilicity of the amorphous part of EVOH eventually causes these problems, and it is considered that these problems can be improved by reducing the hydrophilicity of the amorphous part. .

  As a method for reducing the hydrophilicity of the amorphous part of EVOH, a simple method includes copolymerizing EVOH as a third component with a comonomer having a hydrophobic functional group. However, it is possible to lower the hydrophilicity of the amorphous part by this method, but usually these comonomers are present in EVOH randomly, so that the crystallinity of EVOH itself is lowered, and as a result, the gas barrier property is dependent on humidity. Even if it can be made small, there is a problem in practical use because the level of the entire barrier property is lowered.

  In the crystal structure of EVOH, it is known that the terminal portion of EVOH is not taken into the crystal and exists in the amorphous part. Therefore, the present inventor has paid attention to this point and has studied to introduce a hydrophobic functional group at the end of EVOH. That is, when a hydrophobic functional group is introduced at the end of EVOH, these are present only in the amorphous part, so that the structure of the crystalline part of EVOH is not affected and the hydrophilicity of the amorphous part is reduced. Is possible. The hydrophobic functional group introduced at the terminal may be a simple alkyl group, aryl group, aralkyl group, etc. However, as shown later in Examples and Comparative Examples, these functional groups have insufficient hydrophobicity. Therefore, it is necessary to introduce a more hydrophobic fluorine-containing group.

  The modified EVOH of the present invention preferably has an intrinsic viscosity (η) of 0.014 to 0.072 L / g. Here, η is the following from the number of seconds dropped from a solution obtained by dissolving an ethylene-vinyl alcohol copolymer in a phenol / water = 85/15 (weight ratio) hydrous phenol solution at a measurement temperature of 30 ° C. with an Ostwald viscosity tube. This is a value calculated according to Equation 1.

η = (2 × (η _SP −ln η _r )) ^0.5 / C (L / g) (Formula 1)

{However, the symbols in Formula 1 represent the following:
η _SP = (t−t ₀ ) / t ₀
η _r = t / t ₀
C: EVOH concentration (g / L)
t ₀ : number of seconds (s) of blank (hydrous phenol) falling
t: EVOH solution falling seconds (s)}

  The range of η is more preferably 0.018 to 0.067 L / g, and further preferably 0.021 to 0.062 L / g. When η is less than 0.014 L / g, the molecular weight of the modified EVOH is small, and when treatment such as precipitation or washing is performed in the production process of the modified EVOH, the dissolution of the modified EVOH into these treatment solutions increases and the yield increases. May decrease. When η is greater than 0.072 L / g, the improvement effect of the present invention may rarely be reduced. Examples of a method for adjusting η to the above preferable range include a method for adjusting by changing reaction conditions (solvent ratio, reaction temperature, reaction rate, etc.) of the polymerization step in the method for producing modified EVOH described later. However, it is not limited to this.

  In the modified EVOH of the present invention, the fluorine-containing group content is preferably 0.1 to 40% by weight, more preferably 0.3 to 30% by weight, more preferably 0.5 to 25% in terms of fluorine atoms. More preferably, it is% by weight. When the content of fluorine-containing groups is less than 0.1% by weight in terms of fluorine atoms, the improvement effect of the present invention may be reduced. Moreover, when it exceeds 40 weight%, in the EVOH resin composition which is 2nd invention of this invention mentioned later, the compatibility of EVOH which has a fluorine-containing group at the terminal, and conventional EVOH may fall. As a method for adjusting the content of the fluorinated group to the above preferred range, simply changing the type of the fluorinated group can be mentioned. In addition, when polymerization is performed by a chain transfer reaction method in the modified EVOH production method described later, there is a method of changing conditions such as a solvent ratio, a reaction temperature, a polymerization rate, and an input amount of a mercaptan having a fluorine-containing group. Although it is mentioned, it is not restricted to these.

  The production method of EVOH having a fluorine-containing group at the terminal of the present invention is not particularly limited, and various methods can be exemplified. For example, mercaptan having a fluorine-containing group represented by the above general formula (I) ( In the presence of fluorine-containing mercaptan, radical copolymerization of monomers mainly composed of ethylene and a vinyl ester compound is carried out, and ethylene having a fluorine-containing group introduced at the terminal by a chain transfer reaction A method of producing a vinyl ester copolymer (hereinafter sometimes referred to as EVAc) and then saponifying it (chain transfer reaction method), and an ethylene-vinyl ester having a thioester group or a thiol group at the terminal A copolymer and an epoxy compound having a fluorine-containing group represented by formula (II) (hereinafter referred to as a fluorine-containing epoxy compound) The addition reaction of that), terminal ethylene were introduced fluorine-containing group - after obtaining the vinyl ester copolymer, a method (terminal reactive method of manufacturing by saponifying this) is preferred.

（式中、Ｒ^４及びＲ^５は、それぞれ水素原子又は炭素数１〜５のアルキル基を示し、Ｒ_ｆは上記と同じである）

(Wherein R ⁴ and R ⁵ each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R _f is the same as above)

First, the manufacturing method of EVOH which has a fluorine-containing group at the terminal by the chain transfer reaction method is demonstrated. Examples of the fluorine-containing mercaptans represented by the general formula (I) include compounds in which m is 1, that is, R _f —X—SH (R _f and X are as defined above). _{, H (CF 2) 2 CH} 2 O (CH 2) 3 SH, H (CF 2) 4 CH 2 O (CH 2) 3 SH, H (CF 2) 6 CH 2 O (CH 2) 3 SH, H (CF ₂ ) ₈ CH ₂ O (CH ₂ ) ₃ SH, F (CF ₂ ) ₃ CH ₂ O (CH ₂ ) ₃ SH, F (CF ₂ ) ₅ CH ₂ O (CH ₂ ) ₃ SH, F (CF _{2) 7 CH 2 O (CH} 2) 3 SH, F (CF 2) 9 CH 2 O (CH 2) 3 SH, F (CF 2) 10 (CH 2) 2 O (CH 2) 3 SH, (CF _{3) 2 CF- (CF 2)} 4 (CH 2) 2 O (CH 2) 3 SH, F (CF _{2) 6 CH 2 CH 2 SH} , F (CF 2) 7 CH 2 CH 2 SH, F (CF 2) 8 CH 2 CH 2 SH, F (CF 2) 9 CH 2 CH 2 SH, F (CF 2) ₁₀ CH ₂ CH ₂ SH, F (CF ₂ ) ₈ (CH ₂ ) ₄ SH, (CF ₃ ) ₂ CF— (CF ₂ ) ₆ CH ₂ CH ₂ SH, (CF ₃ ) ₂ CF—O— (CF ₂ ) ₂ CH ₂ CH ₂ SH, (CF ₃ ) ₂ CF—O— (CF ₂ ) ₁₂ CH ₂ CH ₂ SH, (CF ₃ ) ₂ CF—O— (CF ₂ ) ₁₃ —CH ₂ CH ₂ SH, F (CF ₂ ) ₈ CH ₂ CH ₂ N (CH ₃ ) — (CH ₂ ) ₃ SH, F (CF ₂ ) ₈ SCH ₂ CH ₂ SH, F (CF ₂ ) ₁₀ SCH ₂ CH ₂ SH, F (CF _{2 ) 8 CH 2 CH 2 S (} CH 2) 3 SH, F ( _{F 2) 8 SCH 2 CH 2} OCH 2 CH 2 SH, F (CF 2) 8 SCH 2 CH 2 SCH 2 CH 2 SH, F (CF 2) 3 CONHCH 2 CH 2 SH, F (CF 2) 7 CONHCH 2 _{CH 2 SH, F (CF 2} ) 9 CONHCH 2 CH 2 SH, (CF 3) 2 CF-O- (CF (CF 3) -CF 2 -O) 3 -CF (CF 3) -CONHCH 2 CH 2 SH However, it is not limited to these.

In addition, when m is 0, that is, examples of the compound represented by R _f -SH (R _f is the same as above), C ₂ F ₅ SH, C ₄ F ₉ SH, (CF ₃ ) ₂ such as CHCF ₂ SH, and the like. Furthermore, esters such as acetates and benzoates of these fluorine-containing mercaptans can also be used. Among the above-mentioned fluorine-containing mercaptans, particularly H (CF ₂ ) ₄ CH ₂ O (CH ₂ ) ₃ SH, H (CF ₂ ) ₆ CH ₂ O (CH ₂ ) ₃ SH, H (CF ₂ ) ₈ CH _{2 O (CH 2) 3 SH,} F (CF 2) 7 CH 2 O (CH 2) 3 SH, F (CF 2) 9 CH 2 O (CH 2) 3 SH, F (CF 2) 10 (CH 2) _{2 O (CH 2) 3 SH} , (CF 3) 2 CF- (CF 2) 4 (CH 2) 2 O (CH 2) 3 SH, F (CF 2) such as 9 CONHCH ₂ CH ₂ SH is preferred.

  Examples of vinyl ester compounds that can be copolymerized with ethylene include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl caprate, and lauryl. Examples include vinyl acid vinyl, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl pivalate. Among these, vinyl acetate is particularly preferable from the viewpoint of economy.

  Copolymerization of vinyl monomers mainly composed of ethylene and vinyl esters such as vinyl acetate in the presence of fluorine-containing mercaptans can be carried out in the presence of radical polymerization initiators in bulk polymerization, solution polymerization, Any method such as a combination method or an emulsion polymerization method can be used, but in the case of vinyl acetate, a solution polymerization method using methanol as a solvent is most advantageous industrially. There are no particular restrictions on the amount and method of addition of the fluorine-containing mercaptan present during the polymerization to the polymerization system, and it may be appropriately selected according to the physical properties of the target EVOH. As the polymerization method, any of batch, semi-continuous and continuous methods can be used.

  As radical polymerization initiators, 2,2′-azobis (isobutyronitrile), 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- (4-methyl-2) , 4-dimethylvaleronitrile), 2,2'-azobis- (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis- (2-cyclopropylpropionitrile), etc. And diisobutyryl peroxide, cumyl peroxyneodecanoate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, t-butylperoxyneodecanoate, dilauroyl peroxide, benzoyl peroxide And known initiators such as organic peroxide initiators such as t-butyl hydroperoxide. .

  Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of room temperature-150 degreeC is suitable. After polymerization for a predetermined time, unreacted ethylene and vinyl esters are removed by a usual method to obtain an ethylene-vinyl ester copolymer having a fluorine-containing group introduced at the terminal. Thus, by saponifying the ethylene-vinyl ester polymer having a fluorine-containing group introduced into the terminal obtained by the chain transfer reaction method according to a known method described later, the fluorine-containing group is added to the desired terminal. EVOH having is obtained.

  Next, the manufacturing method of EVOH which has a fluorine-containing group at the terminal by the terminal reaction method is demonstrated. Examples of the ethylene-vinyl ester copolymer having a thioester group at the terminal used in this terminal reaction method include thiocarboxylic acids such as thioacetic acid and thiobenzoic acid, 2-acetylthioethanethiol, 2-benzoylthioethanethiol, 10- Diethylthioacetate such as acetylthiodecanethiol, 10-benzoylthiodecanethiol, monobenzoate, etc. are used as chain transfer agents for radical copolymerization of monomers mainly composed of ethylene and vinyl esters, and thioester at one end It is obtained by introducing a group. Further, the ethylene-vinyl ester copolymer having a thiol group at the terminal can be derived from the ethylene-vinyl ester copolymer having a thioester group at one terminal.

On the other hand, the fluorine-containing epoxy compound represented by the general formula (II), for example, in the following general formula (III), _{R f} - _{is, F (CF 2) 2 -} , F (CF 2) 4 -, _{F (CF 2) 6 -,} F (CF 2) 8 -, F (CF 2) 10 -, (CF 3) 2 CF (CF 2) 2 -, (CF 3) 2 CF (CF 2) 4 -, _{(CF 3) 2 CF (CF} 2) 6 -, (CF 3) 2 CF (CF 2) 8 -, H (CF 2) 2 CH 2 O-, H (CF 2) 4 CH 2 O-, H ( Examples thereof include, but are not limited to, CF ₂ ) ₆ CH ₂ O—, H (CF ₂ ) ₈ CH ₂ O—, and the like.

  The reaction between the fluorine-containing epoxy compound and the ethylene-vinyl ester copolymer having a thioester group or thiol group at the end is solvent-free or ethylene- having a thioester group or thiol group at the end without dissolving the fluorine-containing epoxy compound. It is carried out in a solvent that dissolves or swells the vinyl ester copolymer. Examples of such solvents include alcohols such as methanol, ethanol, n-propyl alcohol, and n-butyl alcohol, aromatics such as benzene, toluene, and xylene, ethers such as tetrahydrofuran, dioxane, and diethyl ether, and n-hexane. And hydrocarbons such as water and the like. These may be used alone or in combination of two or more.

  The reaction conditions vary depending on the structure of the fluorine-containing epoxy compound or ethylene-vinyl ester copolymer used. Usually, when a solvent is used, the ethylene-vinyl ester copolymer concentration is 5 to 90% by weight. A range is preferred. Moreover, it is advantageous to select the use ratio of the fluorine-containing epoxy compound and the ethylene-vinyl ester copolymer so that the molar ratio of epoxy group / thioester group or thiol group is in the range of 1.0 to 5.0. is there. The reaction temperature is suitably about 0 to 250 ° C., and the reaction time is suitably about 0.1 to 20 hours.

  Here, it is important to react all the thioester groups or thiol groups contained in the ethylene-vinyl ester copolymer, and in the reaction with thiols, tertiary amines (for example, triethylamine, pyridine, triethanolamine, diethanolamine, ammonia, etc.) ), Phosphines (eg, tributylphosphine, triphenylphosphine, etc.), sodium hydroxide, tetraethylammonium hydroxide, sodium methylate, and other basic compounds, but quaternary ammonium such as tributylammonium chloride, tributylammonium bromide, etc. in the reaction with thioester Each salt is effective as a reaction catalyst. In order to prevent oxidation of thiol, the reaction system can be degassed or replaced with nitrogen, or an antioxidant or the like can be added.

  In this way, the ethylene-vinyl ester copolymer having a fluorine-containing group introduced at the terminal obtained by the terminal reaction method is saponified according to a known method to be described later, thereby having a fluorine-containing group at a desired terminal. EVOH is obtained.

  Next, saponification of an ethylene-vinyl ester copolymer having a fluorine-containing group at the terminal will be described. The ethylene-vinyl ester copolymer obtained by the chain transfer reaction method or the terminal reaction method is saponified by a conventional method. Usually, the ethylene-vinyl ester copolymer is converted into alcohol (1% by weight or less of water). Saponified in a dissolved state. Preferred examples of the alcohol used for the saponification reaction include lower alcohols such as methyl alcohol and ethyl alcohol, and methyl alcohol is particularly preferably used. The alcohol used for the saponification reaction may contain other solvents such as hexane, benzene, and tetrahydrofuran as long as the solubility of EVOH, which is an ethylene-vinyl ester copolymer or a saponification product, is not lowered.

  Usually, the saponification reaction uses, 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 amount of the catalyst used may be appropriately adjusted depending on the target degree of saponification, but it is desirable to use 0.005 or more, preferably 0.008 or more in terms of molar ratio to the vinyl ester unit. On the other hand, if the amount of the catalyst is excessively large, much effort is required to remove the residual catalyst from the EVOH. If the removal of the residual catalyst is insufficient, the EVOH is colored or the thermal stability is lowered. Since it is not preferable, the molar ratio is desirably 0.5 or less.

  Other saponification conditions may be adjusted as appropriate according to the saponification degree of EVOH having a fluorine-containing group at the target end and the physical properties of the ethylene-vinyl ester copolymer, but the reaction temperature ranges from 30 to 150 ° C. The reaction time is suitably from 10 minutes to 6 hours.

  As the saponification method, either a continuous method or a batch method can be used. When continuous saponification is performed, a tower-type saponification apparatus described in JP-A-60-141702, JP-A-2002-69123, or the like is preferably used.

  The EVOH having a fluorine-containing group at the terminal after saponification obtained in this manner usually contains a large amount of the catalyst residue used during saponification, and thus is dried after further washing. Conventionally, when a molded product is produced by melt-molding EVOH, additives such as various metal ions, acids, antioxidants, and lubricants are used for the purpose of improving the thermal stability of EVOH. In addition, for the purpose of improving the handling properties in the EVOH process, EVOH is often processed into various pellet shapes. With regard to these techniques relating to processing, washing, drying, and addition of additives, JP-A Nos. 53-120767, 53-9898, 2001-96529, 2001-98077, 2001-2001. 96606, JP 2001-96530, JP 64-66262, JP 10-67898, JP 2001-164059, WO 03/68847, JP 53-11958 and the like. Although disclosed, these techniques can be directly applied to EVOH having a fluorine-containing group at the terminal of the present invention.

  EVOH having a fluorine-containing group at the terminal of the present invention may be one obtained by copolymerizing other copolymerizable ethylenically unsaturated monomers within a range not impairing the effects of the present invention. Examples of the ethylenically unsaturated monomer include olefins such as propylene, 1-butene and isobutene; and unsaturated groups such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, (anhydrous) maleic acid, and (anhydrous) itaconic acid. Acids, salts thereof and mono- or dialkyl esters having 1 to 18 carbon atoms; acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms, N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid and salts thereof, acrylamidopropyldimethyl Acrylamides such as amines, acid salts thereof and quaternary salts thereof; methacrylamide, N-alkyl methacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamide propanesulfonic acid and salts thereof, methacryl Amidopropyldimethylamine, Methacrylamides such as acid salts and quaternary salts thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide and N-vinylacetamide; Vinyl cyanides such as acrylonitrile and methacrylonitrile; 18 vinyl ethers such as alkyl vinyl ether, hydroxyalkyl vinyl ether and alkoxyalkyl vinyl ether; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinyl silane; acetic acid Allyl, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid, Such as hydroxyalkyl group-containing α- olefins prime 1-20 thereof.

  Next, an ethylene-vinyl alcohol copolymer resin composition which is another invention of the present invention will be described.

  The EVOH resin composition of the present invention comprises an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more, and a fluorine-containing group at the terminal of the first invention of the present invention. It is an ethylene-vinyl alcohol copolymer resin composition comprising an ethylene-vinyl alcohol copolymer (B) having (A) / (B) of 99/1 to 50/50 (weight ratio). That is, by blending EVOH having a fluorine-containing group at the terminal of the present invention with conventional EVOH, the humidity dependency and water vapor barrier property of gas barrier properties, which are problems in conventional EVOH, are improved.

  The ethylene-vinyl alcohol copolymer (A) used in the EVOH resin composition of the present invention has an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more. As long as this is satisfied, any conventionally known EVOH can be used.

  The ethylene content of EVOH (A) is preferably 22 to 55 mol%, more preferably 24 to 50 mol%. When the ethylene content is less than 20 mol%, the thermal stability of EVOH is lowered, and when it is 60 mol% or more, the gas barrier property is lowered, which is not preferable.

  The saponification degree of EVOH (A) is preferably 95 mol% or more, more preferably 98 mol% or more, and further preferably 99 mol% or more. A saponification degree of less than 90 mol% is not preferable because not only the gas barrier property is lowered but also the thermal stability of EVOH is lowered.

  The ethylene-vinyl alcohol copolymer (B) having a fluorine-containing group at the terminal used in the EVOH resin composition of the present invention (hereinafter, sometimes referred to as modified EVOH (B)) is the first invention of the present invention. This is the same as EVOH having a fluorine-containing group at a certain end. The preferred range of η, ethylene content, degree of saponification, fluorine-containing group type and content (in terms of fluorine atoms) of the modified EVOH (B) is as described in the first invention of the present invention.

  The composition of EVOH (A) and modified EVOH (B) is 99/1 to 50/50 (weight ratio), preferably 98/2 to 60/40, more preferably 97/3 to 70/30. More preferably 96/4 to 75/25, and particularly preferably 95/5 to 80/20. When the ratio of EVOH (A) to modified EVOH (B) is 99/1 or more, the improvement effect of the present invention becomes small. Even if the ratio of EVOH (A) to modified EVOH (B) is made smaller than 50/50, the improvement effect of the present invention is hardly changed, so it is meaningless.

  The method for blending EVOH (A) and modified EVOH (B) is not particularly limited. A method of melt blending with an extruder or the like, a method of blending as a solution dissolved in an appropriate solvent, or a method of dry blending in a solid state. Any method may be used.

  In the EVOH resin composition of the present invention, the intrinsic viscosity (η) of EVOH (A) is more preferably 0.059 to 0.177 L / g in terms of mechanical properties of the molded product. The η range of EVOH (A) is more preferably 0.066 to 0.147 L / g, and still more preferably 0.073 to 0.127 L / g. When η is less than 0.059 L / g, the mechanical properties may be insufficient depending on the type and use of the molded product. There is no problem even if EVOH (A) having η larger than 0.177 L / g is used, but even if EVOH (A) having a larger η is used, the mechanical properties are not improved so much.

  Hereinafter, the uses of the modified EVOH and EVOH resin composition of the present invention (hereinafter simply referred to as “EVOH resin composition of the present invention”) will be described.

  The obtained EVOH resin composition of the present invention is molded into various molded products such as films, sheets, containers, pipes, fibers, etc. by melt molding. These molded products can be pulverized and molded again for reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers, and the like. As the melt molding method, extrusion molding, inflation extrusion, blow molding, melt spinning, injection molding and the like are possible. The melting temperature varies depending on the melting point of the copolymer, but is preferably about 150 to 270 ° C.

  The EVOH resin composition and the like of the present invention can be used as a molded product composed of only a single layer of the resin composition or the like of the present invention, but for the purpose of obtaining a molded product having the characteristics of various thermoplastic resins. A multilayer structure including at least one layer composed of the EVOH resin composition of the present invention is preferable. The layer structure of the multilayer structure is represented by E / T, T / E / T, E / Ad / T, where E is the EVOH resin composition of the present invention, Ad is the adhesive resin, and T is the thermoplastic resin. , T / Ad / E / Ad / T and the like, but are not limited thereto. Each of the layers shown here may be a single layer or may be a multilayer according to circumstances.

  The method for producing the multilayer structure shown above is not particularly limited. For example, a method of melt-extruding a thermoplastic resin on a molded article (film, sheet, etc.) comprising the EVOH resin composition of the present invention, and conversely, an EVOH resin composition of the present invention on a substrate such as a thermoplastic resin And other thermoplastic resins, a method of co-extrusion or co-injection of the thermoplastic resin and the EVOH resin composition of the present invention, and a molded product obtained from the EVOH resin composition of the present invention. And a method of laminating films and sheets of other substrates with known adhesives such as organic titanium compounds, isocyanate compounds, and polyester compounds. Of these, the method of co-extrusion or co-injection is preferred.

  The method of coextrusion molding of the EVOH resin composition and the like of the present invention and the thermoplastic resin is not particularly limited, and a multi-manifold merging method T-die method, a feed block merging method T-die method, an inflation method, etc. are exemplified as suitable ones. Is done. Further, the method of co-injection molding is not particularly limited, and a general method can be used.

  Examples of the thermoplastic resin used for laminating with the EVOH resin composition of the present invention include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene- Propylene copolymer, polypropylene, propylene-α-olefin copolymer (α-olefin having 4 to 20 carbon atoms), polybutene, polypentene and other olefins alone or copolymers thereof, polyesters such as polyethylene terephthalate, polyester elastomers, Polyamide resins such as nylon-6, nylon-6,6, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyurethane elastomers, polycarbonates, chlorinated polyethylene, chlorinated polypropylene, etc. I can get lost. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.

  When laminating the EVOH resin composition or the like of the present invention and a thermoplastic resin, an adhesive resin may be used. In this case, an adhesive resin made of a carboxylic acid-modified polyolefin is preferable. Here, the carboxylic acid-modified polyolefin is a modified olefinic polymer containing a carboxyl group obtained by chemically (for example, by addition reaction or graft reaction) bonding an ethylenically unsaturated carboxylic acid or its anhydride to an olefin polymer. Refers to coalescence. In addition, the olefin polymer is a polyethylene (low pressure, medium pressure, high pressure), a polyolefin such as linear low density polyethylene, polypropylene, boribten, or the like, a comonomer (vinyl ester, non-polymer) capable of copolymerizing the olefin and the olefin. Means a copolymer with a saturated carboxylic acid ester and the like, for example, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ethyl ester copolymer, and the like. Of these, linear low density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content 5-55 wt%), ethylene-acrylic acid ethyl ester copolymer (acrylic acid ethyl ester content 8-35 wt. %), Linear low density polyethylene and ethylene-vinyl acetate copolymers are particularly preferred. Examples of the ethylenically unsaturated carboxylic acid or its anhydride include ethylenically unsaturated monocarboxylic acid, its ester, ethylenically unsaturated dicarboxylic acid, its mono or diester, and its anhydride. Among these, ethylenically unsaturated dicarboxylic acid Anhydrides are preferred. Specific examples include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester. Acid is preferred.

  The addition amount or graft amount (degree of modification) of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer is 0.01 to 15% by weight, preferably 0.02 to 10% by weight, based on the olefin polymer. It is. The addition reaction and grafting reaction of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer can be obtained, for example, by radical polymerization in the presence of a solvent (such as xylene) or a catalyst (such as a peroxide). The melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g of the carboxylic acid-modified polyolefin thus obtained is preferably 0.2 to 30 g / 10 minutes, more preferably 0.5 to 10 g. / 10 minutes. These adhesive resins may be used alone or in combination of two or more.

By subjecting the coextruded multilayer structure or co-injection multilayer structure thus obtained to secondary processing, various molded articles (films, sheets, tubes, bottles, etc.) can be obtained. Examples include the following.
(1) A multilayer structure (sheet or film, etc.) is stretched uniaxially or biaxially, and a multilayer co-stretched sheet or film by heat treatment as required (2) A multilayer structure (sheet or film, etc.) is rolled Multi-layer rolled sheet or film by (3) Multi-layer structure (sheet or film, etc.) Multi-layer tray cup-shaped container by thermoforming such as vacuum forming, pressure forming, vacuum-pressure forming, etc. (4) Multi-layer structure (pipe) Etc.) bottles by stretch blow molding, etc., cup-like containers (5) bottle-like containers by biaxial stretch blow molding from multilayer structures (parison etc.)

  There is no restriction | limiting in particular in such a secondary processing method, The well-known secondary processing methods other than the above can also be employ | adopted. The coextruded multilayer structure or co-injection multilayer structure obtained in this way has excellent interlayer adhesion, good appearance, and odor generation is suppressed, so various food container materials such as packaging films It is preferably used as a material for deep-drawn containers, cup-shaped containers, bottles and the like.

  Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to this example. Hereinafter, “%” and “parts” are based on weight unless otherwise specified.

[Method for measuring ethylene content and saponification degree of EVOH]
1H-NMR measurement (manufactured by JEOL Ltd., superconducting nuclear magnetic resonance apparatus Lambda 500) was performed on a solution in which EVOH was dissolved at a concentration of 5 wt% using HFIP-d ₂ as a solvent, and from the peak area ratio of the obtained spectrum, the following was performed. The ethylene content and degree of saponification of EVOH were measured.
Ethylene content (mol%) = (3A + 4B-6C) / (3A + 4B + 6C) × 100
Degree of saponification (mol%) = 3C / (3C + D) × 100
A: Integrated value of peak of 1.2 to 2.0 ppm (derived from CH ₂ in polymer skeleton)
B: Integrated value of peak from 0.8 to 1.1 ppm (derived from CH ₃ at the polymer end)
C: Integrated value of peak at 3.5 to 4.5 ppm (derived from hydroxyl group of polymer side chain)
D: Integrated value of peak of 2.0 to 2.2 ppm (derived from residual acetic acid group CH ₃ )

[Measurement method of intrinsic viscosity (η) of EVOH]
Then, 0.20 g of EVOH was precisely weighed and dissolved in 40 mL of hydrous phenol containing phenol / water = 85/15 (weight ratio) at 60 ° C. and heated and stirred for 4 hours. The obtained EVOH solution was filtered through a glass filter, and the number of seconds dropped was measured at a measurement temperature of 30 ° C. using an Ostwald viscosity tube (a blank water-containing phenol having a drop time of about 90 seconds). Separately, with respect to the same hydrous phenol having EVOH dissolved as a blank, the falling seconds were measured under the same conditions, and the intrinsic viscosity (η) of EVOH was determined from these measured values according to the above-mentioned formula 1.

[Content of fluorine-containing group introduced into EVOH]
Exactly weighed 0.05 g of EVOH was burned by an oxygen flask combustion method, and the generated gas was absorbed in 50 mL of the following eluent to prepare a sample solution. About the created sample solution, fluoride ion was quantified by ion chromatography (IC 7000 manufactured by Yokogawa Analytical Systems), and the fluorine-containing group content in EVOH was determined in terms of fluorine atoms. The measurement conditions for ion chromatography are shown below.
Column: ICS-A23 manufactured by Yokogawa Analytical Systems
Column temperature: 40 ° C
Eluent: Mixed aqueous solution of Na ₂ CO ₃ 2.5 mM and NaHCO ₃ 1.0 mM Eluent flow rate: 1 mL / min.
Suppressor removal solution: H ₂ SO ₄ 15 mM aqueous solution Sample solution injection volume: 50 μL

[Method for evaluating the dependence of gas barrier properties on humidity]
Using EVOH solution in which EVOH was dissolved in m-cresol at a concentration of 15 to 25% by weight (adjusted appropriately by EVOH η), it was hand-coated on a 100 μm-thick PET film by a bar coating method. After drying, the film was peeled from the PET film to prepare an EVOH film having a thickness of about 20 μm. About the created film, MODERN CONTROLS INC. Oxygen permeability under conditions of 30 ° C., 65% RH and 30 ° C., 95% RH in accordance with the method described in JIS K7126 (isobaric method) using an oxygen permeability measuring device MOCONOX-TRAN10 / 50A type (OTR ⁶⁵ and OTR ⁹⁵ , respectively) were measured (where oxygen permeability was a value obtained by converting oxygen permeability measured at an arbitrary film thickness into oxygen permeability at a film thickness of 20 μm).

[Method of evaluating moisture permeability]
With respect to the EVOH film prepared by the same method as described above, the moisture permeability was measured according to the description of JIS Z0208 under the conditions of 40 ° C. and 90% RH, and the value obtained by converting the film thickness to 30 μm was calculated.

[Evaluation method of mechanical properties]
Autograph AGS-H manufactured by Shimadzu Corporation was used for a sample obtained by conditioning a EVOH film prepared by the same method as described above for 7 days in an atmosphere of 23 ° C. and 50% RH and cutting out a strip-shaped test piece having a width of 15 mm. Using the mold, the tensile strength at break was measured under conditions of a chuck interval of 50 mm and a tensile speed of 500 mm / min. The measurement was performed for each 10 samples, and the average value was obtained.

[Synthesis of fluorine-containing mercaptans]
Synthesis example 1
122 g of F- (CF ₂ ) _10- (CH) ₂ OH was dissolved in 100 ml of dimethyl sulfoxide, 22.4 g of sodium hydroxide was added, and then 33 g of allyl chloride was added dropwise over 2 hours while stirring at room temperature. After completion of the dropwise addition, the mixture was further stirred at room temperature for 5 hours, and then the filtrate obtained by filtering the precipitate was heated in a warm water bath to remove unreacted allyl chloride. Next, the filtrate was poured into a large amount of water, and F— (CF ₂ ) ₁₀ — (CH) ₂ OCH ₂ —CH═CH ₂ was separated by a separatory funnel. To the obtained F- (CF ₂ ) ₁₀ — (CH) ₂ OCH ₂ —CH═CH ₂ , 5 mg of benzoyl peroxide was added, and 25 g of thioacetic acid was added dropwise over 2 hours while stirring at room temperature to carry out the reaction. . After removing unreacted thioacetic acid from the reaction solution under reduced pressure, 100 mL of methanol and 10 g of sodium hydroxide were added, and the reaction was performed at 60 ° C. for 3 hours. The reaction solution after the reaction was cooled to room temperature, poured into a large amount of water, and then separated by a separatory funnel to obtain a crude product. This is purified by distillation under reduced pressure, as the fluorine-containing mercaptan _{F- (CF 2) 10 - (} CH 2) 2 O (CH 2) 3 was obtained -SH (F-1).

Synthesis example 2
In Synthesis Example 1, it was used as the raw material _{F- (CF 2) 10 - (} CH 2) instead of _{2 OH 122g, (CF 3)} 2 CF (CF 2) 4 - was used _(CH 2) 2 OH 89g Except for the above, fluorine group-containing mercaptan (CF ₃ ) ₂ CF (CF ₂ ) ₄ — (CH ₂ ) ₂ O (CH ₂ ) ₃ —SH (F-2) was synthesized in the same manner as in Synthesis Example 1.

Synthesis example 3
In Synthesis Example 1, Synthesis Example 1 was used except that 50 g of H— (CF ₂ ) ₄ —CH ₂ OH was used instead of 122 g of F— (CF ₂ ) ₁₀ — (CH ₂ ) ₂ OH used as a raw material. Similarly, fluorine group-containing mercaptan H— (CF ₂ ) ₄ —CH ₂ O (CH ₂ ) ₃ —SH (F-3) was synthesized.

[Example 1]
Synthesized in 1.47 kg of vinyl acetate, 1.04 kg of methanol and Synthesis Example 1 in a 5 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet, initiator addition port and delay (sequential addition) solution addition port Fluorine group-containing mercaptan (F-1) (1.93 g) was charged, the temperature was raised to 60 ° C., and the system was purged with nitrogen by nitrogen bubbling for 30 minutes. Next, ethylene was introduced and charged so that the reactor pressure was 3.1 MPa. A 2,3'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol as an initiator was adjusted to a concentration of 3.5 g / L, and nitrogen substitution was performed for bubbling with nitrogen gas. did. Further, a 20% concentration solution in which F-1 was dissolved in methanol was prepared as a delay solution, and nitrogen substitution was performed to perform bubbling with nitrogen gas. After adjusting the temperature inside the polymerization tank to 60 ° C., 16 ml of the initiator solution was injected to start polymerization. During the polymerization, ethylene was introduced to maintain the reaction vessel pressure at 3.1 MPa, the polymerization temperature at 60 ° C., AMV at 50 ml / hr using the above initiator solution, and F− using the above delay solution. Polymerization was carried out by continuously adding 1 while keeping the ratio of vinyl acetate and F-1 in the polymerization system constant. After 4.0 hours, when the polymerization rate reached 50%, the polymerization was stopped by cooling. At this time, the total amount of the F-1 delay solution added by the delay was 189 ml. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Subsequently, the unreacted vinyl acetate monomer was removed under reduced pressure to prepare a methanol solution of an ethylene-vinyl acetate copolymer having a fluorine-containing group derived from F-1 at the terminal. 20.2 g (molar ratio of vinyl acetate unit in EVAc) to 100 g of EVAc methanol solution adjusted to 50% by adding methanol to the obtained EVAc solution (50 g of EVAc in solution). MR) 0.2) alkaline solution (NaOH in 20% methanol) was added and stirred at 60 ° C. for 8 hours to saponify EVAc. After completion of the reaction, methanol and methyl acetate as a by-product were removed under reduced pressure, and further washed with tap water, then dried in a hot air dryer at 80 ° C. for 16 hours, and the ethylene-vinyl alcohol having a fluorine-containing group at the end was dried. A polymer (E-1) was obtained.

  The obtained E-1 was analyzed according to the above. As a result, the ethylene content was 32 mol%, the saponification degree was 99.9 mol%, the intrinsic viscosity was 0.0370 L / g, and the fluorine-containing group content was 3. 1%.

  Using a 20% concentration solution of E-1 dissolved in m-cresol, an EVOH film was prepared according to the above, and using this, the humidity dependency of the gas barrier property and the evaluation of the water vapor barrier property were performed according to the above. . The results are shown in Table 2.

[Examples 2 to 9]
Polymerization of EVAAc was carried out in the same manner as in Example 1 except that the conditions such as the type and amount of the fluorine-containing mercaptan used in the polymerization of EVAc, the composition of the feed, the reaction time, the polymerization rate, etc. were changed as shown in Table 1. Thereafter, saponification, purification and drying were carried out in the same manner as in Example 1 to obtain EVOH (E-2 to 9) having fluorine-containing groups at various terminals. The results of these analyzes are shown in Table 2. Next, with respect to these EVOHs, the humidity dependency of the gas barrier property and the water vapor barrier property were evaluated in the same manner as in Example 1 except that the concentration of the EVOH solution to be adjusted at the time of film formation was appropriately adjusted. These evaluation results are also shown in Table 2.

[Example 10]
A 5 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet, initiator addition port and delay solution addition port was charged with 1.47 kg of vinyl acetate, 1.04 kg of methanol and 0.64 g of thioacetic acid, and 60 ° C. The temperature in the system was replaced with nitrogen by nitrogen bubbling for 30 minutes. Next, ethylene was introduced and charged so that the reactor pressure was 3.1 MPa. A 3.5 g / L solution having AMV dissolved in methanol as an initiator was prepared, and nitrogen substitution was performed for bubbling with nitrogen gas. Further, a 4% concentration solution of thioacetic acid dissolved in methanol was prepared as a delay solution, and nitrogen substitution was performed to perform bubbling with nitrogen gas. After adjusting the temperature inside the polymerization tank to 60 ° C., 18 ml of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 3.1 MPa, the polymerization temperature at 60 ° C., AMV at 55 ml / hr using the above initiator solution, and thioacetic acid using the above delay solution. Was continuously added while maintaining the ratio of vinyl acetate and thioacetic acid in the polymerization system to be constant. After 4.0 hours, when the polymerization rate reached 50%, the polymerization was stopped by cooling. At this time, the total amount of the thioacetic acid delay solution added by the delay was 123 ml. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Subsequently, the unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of an ethylene-vinyl acetate copolymer having an acetylthio group at the terminal. Next, in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, 100 g of EVAc methanol solution (concentration 60%) having a thioester group at the terminal obtained above, 3-perfluorodecyl- After charging 3.1 g of 1,2-epoxypropane and 50 g of methanol and bubbling nitrogen gas for 15 minutes, 0.6 mL of a methanol solution of sodium hydroxide (concentration 20%) was added. After reacting at 40 ° C. for 2 hours with stirring, 24 mL of a 20% strength sodium hydroxide methanol solution was further added at the same temperature for saponification. EVAAc saponification was performed by stirring at 60 ° C. for 8 hours. After completion of the reaction, methanol and methyl acetate as a by-product were removed under reduced pressure, and further washed with tap water, then dried in a hot air dryer at 80 ° C. for 16 hours, and the ethylene-vinyl alcohol having a fluorine-containing group at the end was dried. A polymer (E-10) was obtained. The analysis results of E-10 are shown in Table 2. Next, in the same manner as in Example 1, evaluation of humidity dependency of the gas barrier property of E-10 was performed. The results are also shown in Table 2.

[Comparative Examples 1-5]
Various EVOHs (E-11 to 15) were used in the same manner as in Example 1 except that the conditions such as the type of mercaptan used in the polymerization of EVAc, the composition of the charge, the reaction time, and the polymerization rate were changed as shown in Table 1. Synthesis and physical properties were evaluated and analyzed according to the above. The analysis results and physical property evaluation results are also shown in Table 2.

[Comparative Example 6]
A 5 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet, initiator addition port and delay solution addition port was charged with 1.06 kg of vinyl acetate, 1.41 kg of methanol and 7.7 g of allyl glycidyl ether, After raising the temperature to 0 ° C., the system was purged with nitrogen by nitrogen bubbling for 30 minutes. Next, ethylene was introduced and charged so that the reactor pressure was 2.5 MPa. A 3.5 g / L solution having AMV dissolved in methanol as an initiator was prepared, and nitrogen substitution was performed for bubbling with nitrogen gas. After adjusting the polymerization tank internal temperature to 60 ° C., 30 ml of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 2.5 MPa and the polymerization temperature at 60 ° C., and polymerization was carried out by continuously adding AMV at 94 ml / hr using the above initiator solution. After 5.9 hours, when the polymerization rate reached 75%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Subsequently, the unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of an ethylene-vinyl acetate copolymer having an epoxy group in the side chain. Next, in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, 100 g of EVAc methanol solution (concentration 60%) having an epoxy group in the side chain obtained above, fluorine-containing mercaptan (F -1) After charging 3.0 g and 50 g of methanol and bubbling nitrogen gas for 15 minutes, 0.6 mL of a sodium hydroxide methanol solution (concentration 20%) was added. The mixture was reacted at 40 ° C. for 2 hours, then heated to 60 ° C., and further saponified by adding 24 mL of a 20% strength sodium hydroxide methanol solution. EVAAc saponification was performed by stirring at 60 ° C. for 8 hours. After completion of the reaction, methanol and by-product methyl acetate were removed under reduced pressure, and further washed with tap water, then dried in a hot air dryer at 80 ° C. for 16 hours and ethylene-vinyl alcohol having a fluorine-containing group in the side chain A copolymer (E-16) was obtained. The analysis results of E-16 are shown in Table 2. Next, in the same manner as in Example 1, evaluation of humidity dependency of the gas barrier property of E-10 was performed. The results are also shown in Table 2.

[Comparative Example 7-9]
The ethylene-vinyl alcohol copolymer was used in the same manner as in Example 1 except that no fluorine group-containing mercaptan was used during the polymerization of EVAc, and the conditions such as the feed composition, reaction time, and polymerization rate were changed as shown in Table 1. The union (E-17-19) was obtained. The analysis results of these EVOH and the evaluation results such as the humidity dependence of the gas barrier properties are also shown in Table 2.

[Example 11]
The modified EVOH (E-1) synthesized in Example 1 and EVOH (E-17) synthesized in Comparative Example 7 were dry blended at a ratio of E-1 / E-17 = 10/90 to obtain an EVOH resin composition. This resin composition was evaluated for the humidity dependency, water vapor barrier property, and mechanical properties of the gas barrier property described above. The results are shown in Table 3.

[Examples 12 to 16]
An EVOH resin composition was prepared in the same manner as in Example 11 except that the type of EVOH used for blending and the blend ratio were changed as shown in Table 3, and the gas barrier property was evaluated for humidity dependency. The results are also shown in Table 3.

[Comparative Examples 10 to 13]
An EVOH resin composition was prepared in the same manner as in Example 11 except that the type of EVOH used for blending and the blend ratio were changed as shown in Table 3, and the gas barrier property was evaluated for humidity dependency. The results are also shown in Table 3.

As is clear from the above Examples and Comparative Examples, the EVOH or EVOH resin composition that satisfies the requirements of the present invention exhibits the physical properties excellent in the humidity dependency of the gas barrier property and the water vapor barrier property.

Claims (8)

The ethylene content is 20 to 60 mol%, the saponification degree is 90 mol% or more, and the following general formula (I)
R _f -X _m- (I)
(However, _{R f H- (CF 2) 2} -, H- (CF 2) 4 -, H- (CF 2) 6 -, H- (CF 2) 8 -, F (CF 2) 2 -, _{F (CF 2) 3 -,} F- (CF 2) 4 -, F- (CF 2) 5 -, F- (CF 2) 6 -, F- (CF 2) 7 -, F- (CF 2) _{8 -, F- (CF 2)} 9 -, F- (CF 2) 10 -, (CF 3) 2 CF- (CF 2) 2 -, (CF 3) 2 CF- (CF 2) 4 -, ( _{CF 3) 2 CF- (CF 2} ) 6 -, (CF 3) 2 CF- (CF 2) 8 -, (CF 3) 2 CF-O- (CF 2) 2 -, (CF 3) 2 CF- _{O- (CF 2) 12 -,} (CF 3) 2 CF-O- (CF 2) 13 -, (CF 3) 2 CH- (CF 2) 2 -, (CF 3) 2 CF-O- [ CF (CF ₃ ) —CF ₂ —O] ₃ —CF (CF ₃ ) —, and X represents —CH ₂ —O— (CH ₂ ) ₃ —, — (CH ₂ ) ₂ —O— ( _{CH 2) 3 -, - (} CH 2) 2 -, - (CH 2) 4 -, - S- (CH 2) 2 -, - (CH 2) 2 -S- (CH 2) 3 -, - S _{- (CH 2) 2 -O- (} CH 2) 2 -, - S- (CH 2) 2 -S- (CH 2) 2 -, - CONH- (CH 2) 2 -, - (CH 2) 2 _{-COO- (CH 2) 3 -,} - COO- (CH 2) 3 -, - CH 2 -CH (OH) -CH 2 -, - CH 2 -CH (CH 2 OH) - represents one of, m is 0 or 1.)
A gas barrier material comprising an ethylene-vinyl alcohol copolymer having a fluorine-containing group represented by the formula: The gas barrier according to claim 1, wherein the main chain chain length of the fluorine-containing group of the ethylene-vinyl alcohol copolymer is 3 to 30, and the ratio of fluorine atoms in the fluorine-containing group is 30% by weight or more. Wood . The gas barrier material according to claim 1 or 2, wherein the intrinsic viscosity (η) of the ethylene-vinyl alcohol copolymer is 0.014 to 0.072 L / g. Here, η is the following from the number of seconds dropped from a solution obtained by dissolving an ethylene-vinyl alcohol copolymer in a phenol / water = 85/15 (weight ratio) hydrous phenol solution at a measurement temperature of 30 ° C. with an Ostwald viscosity tube. This is a value calculated according to Equation 1.

η = (2 × (η _SP −ln η _r )) ^0.5 / C (L / g) (Formula 1)
{However, the symbols in Formula 1 represent the following:
η _SP = (t−t ₀ ) / t ₀
η _r = t / t ₀
C: EVOH concentration (g / L)
t ₀ : number of seconds (s) of blank (hydrous phenol) falling
t: EVOH solution falling seconds (s)}
The gas barrier material according to any one of claims 1 to 3, wherein the fluorine-containing group content of the ethylene-vinyl alcohol copolymer is 0.1 to 40% by weight in terms of fluorine atoms. The gas barrier material according to any one of claims 1 to 4 , wherein the saponification degree of the ethylene-vinyl alcohol copolymer is 99 mol% or more. An ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more; an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more; )
R _f -X _m- (I)
(However, _{R f H- (CF 2) 2} -, H- (CF 2) 4 -, H- (CF 2) 6 -, H- (CF 2) 8 -, F (CF 2) 2 -, _{F (CF 2) 3 -,} F- (CF 2) 4 -, F- (CF 2) 5 -, F- (CF 2) 6 -, F- (CF 2) 7 -, F- (CF 2) _{8 -, F- (CF 2)} 9 -, F- (CF 2) 10 -, (CF 3) 2 CF- (CF 2) 2 -, (CF 3) 2 CF- (CF 2) 4 -, ( _{CF 3) 2 CF- (CF 2} ) 6 -, (CF 3) 2 CF- (CF 2) 8 -, (CF 3) 2 CF-O- (CF 2) 2 -, (CF 3) 2 CF- _{O- (CF 2) 12 -,} (CF 3) 2 CF-O- (CF 2) 13 -, (CF 3) 2 CH- (CF 2) 2 -, (CF 3) 2 CF-O- [ CF (CF ₃ ) —CF ₂ —O] ₃ —CF (CF ₃ ) —, and X represents —CH ₂ —O— (CH ₂ ) ₃ —, — (CH ₂ ) ₂ —O— ( _{CH 2) 3 -, - (} CH 2) 2 -, - (CH 2) 4 -, - S- (CH 2) 2 -, - (CH 2) 2 -S- (CH 2) 3 -, - S _{- (CH 2) 2 -O- (} CH 2) 2 -, - S- (CH 2) 2 -S- (CH 2) 2 -, - CONH- (CH 2) 2 -, - (CH 2) 2 _{-COO- (CH 2) 3 -,} - COO- (CH 2) 3 -, - CH 2 -CH (OH) -CH 2 -, - CH 2 -CH (CH 2 OH) - represents one of, m is 0 or 1.)
In ethylene having represented by fluorine-based - it from vinyl alcohol copolymer (B), and ethylene is (A) / (B) is 99 / 1-50 / 50 (weight ratio) - vinyl alcohol copolymerization A gas barrier material comprising a coalesced resin composition. The gas barrier material according to claim 6, wherein the intrinsic viscosity of the ethylene-vinyl alcohol copolymer (A) is 0.059 to 0.177 L / g. A packaging material comprising the gas barrier material according to any one of claims 1 to 7.