JP7059202B2 - Crosslinkable resin compositions and crosslinked products, their production methods, and multilayer structures. - Google Patents

Description

The present invention relates to resin compositions and crosslinked products, methods for producing them, and multilayer structures.

Ethylene-vinyl alcohol copolymer (hereinafter, also simply referred to as "EVOH") has a very small oxygen permeation amount as compared with other plastics and has good melt moldability. Widely used as a packaging material. However, when the packaging material using EVOH is retort-treated or used for a long time under high temperature and high humidity conditions, whitening or deformation may occur or the barrier property may be deteriorated. Was required to improve. Further, when EVOH is used for industrial pipe applications, improvement in heat-resistant solvent resistance has been required.

As a measure for improving heat-resistant water-resistant water-resistant solvent-resistant properties, various techniques have been proposed in which EVOH is crosslinked by using an active energy ray such as an electron beam. For example, Patent Document 1 discloses a method in which triallyl cyanurate or triallyl isocyanurate is used as a cross-linking agent, and these are melt-kneaded with EVOH and then irradiated with an electron beam for cross-linking.

Further, Patent Document 2 discloses a method of adding a compound having two or more allyl ether groups to EVOH and irradiating it with an electron beam to crosslink it.

Further, in Patent Document 3, EVOH is modified with an epoxy compound having a double bond and an epoxy compound having no double bond, and at least a part of the obtained modified EVOH is crosslinked by irradiating with an electron beam. The method is disclosed.

Further, Patent Document 4 discloses a method of adding an amide compound having a plurality of double bonds to EVOH and irradiating it with an electron beam to crosslink it.

Japanese Patent Application Laid-Open No. 62-252409 Japanese Unexamined Patent Publication No. 9-234833 International Publication No. 2007/123108 International Publication No. 2011/111802

However, the multilayer film obtained by laminating the film using the crosslinked product obtained in Patent Document 1 or Patent Document 2 may have insufficient interlayer adhesiveness, and there is room for improvement in heat resistance water resistance and heat resistance solvent resistance. there were. The crosslinked product of Patent Document 3 requires a special extruder to denature EVOH, and has a problem of lacking versatility. Patent Document 4 describes that bleed-out can be effectively suppressed by giving a specific polar group to the cross-linking agent and bringing the SP value close to the SP value of EVOH. Since bleed-out of the cross-linking agent is not sufficiently suppressed depending on the type of EVOH used, there is a concern about hygiene problems when it is used as a packaging material.

The present invention has been made based on the above circumstances, and an object thereof is a resin composition capable of forming a crosslinked product having excellent heat-resistant water-resistant property, heat-resistant solvent property, and interlayer adhesion when formed into a multilayer structure. Is provided without limitation on the type of EVOH used.

The present inventors have found that a crosslinkable compound having a specific chemical structure such as the type and symmetry of a functional group has a particularly high crosslinking effect on EVOH and improves heat resistant water and heat resistant solvent resistance. In addition, the present inventors consider that the factors that cause the crosslinkable compound to bleed out are not only the chemical interaction between EVOH and the crosslinker, but also the physical state and molecular weight (molecular size) of the crosslinker. And came to the present invention. The inventions made to solve the above problems are as follows.

(1) A resin composition containing 0.4 to 10 parts by mass of the cross-linking agent (B) with respect to 100 parts by mass of the ethylene-vinyl alcohol copolymer (A), and the cross-linking agent (B) is 3 or more. A resin composition which is a triazine derivative having a polymerizable group and having a melting point of more than 40 ° C.;
(2) The cross-linking agent (B) contains at least one selected from the group consisting of a polymer of triallyl cyanurate, a polymer of triallyl isocyanurate, a polymer of trimetalyl isocyanurate and a polymer of trimetalyl isocyanurate. The resin composition according to 1);
(3) The resin composition according to (1) or (2) above, wherein the cross-linking agent (B) is trimetalyl isocyanurate.
(4) The above (1) further contains 0.05 to 10 parts by mass of a hindered phenolic compound (C) having an ester bond or an amide bond with respect to 100 parts by mass of the ethylene-vinyl alcohol copolymer (A). The resin composition according to any one of (3);
(5) The resin composition according to (4) above, wherein the hindered phenolic compound (C) has an amide bond;
(6) The resin composition according to any one of (1) to (5) above, which is used for active energy ray cross-linking;
(7) A crosslinked product obtained from the resin composition according to any one of (1) to (6) above;
(8) A film made of the crosslinked product according to (7) above;
(9) A multilayer structure having a layer made of the crosslinked product according to (7) above;
(10) A retort container having the multilayer structure according to (9) above;
(11) A pipe having the multilayer structure according to (9) above;
(12) A copolymerization step of copolymerizing ethylene and a vinyl ester to obtain an ethylene-vinyl ester copolymer, and saponifying the ethylene-vinyl ester copolymer to obtain an ethylene-vinyl alcohol copolymer (A). The resin according to any one of (1) to (6) above, which comprises a saponification step and a mixing step of mixing the ethylene-vinyl alcohol copolymer (A) and the cross-linking agent (B) to obtain a mixture. Method for producing the composition;
(13) A copolymerization step of copolymerizing ethylene and vinyl ester to obtain an ethylene-vinyl ester copolymer, and cross-linking the ethylene-vinyl ester copolymer to obtain an ethylene-vinyl alcohol copolymer (A). A saponification step, a mixing step of mixing the ethylene-vinyl alcohol copolymer (A) and the cross-linking agent (B) to obtain a mixture, and a cross-linking step of irradiating the mixture obtained in the mixing step with active energy rays. The method for producing a crosslinked product according to (7) above, which comprises.

The resin composition of the present invention can form a crosslinked product having excellent heat-resistant water-resistant and heat-resistant solvent properties. Further, the multilayer structure using the crosslinked product is excellent in interlayer adhesiveness.

<Resin composition>
The resin composition of the present invention contains EVOH (A) and a cross-linking agent (B). In the resin composition, since the cross-linking agent (B) uses a triazine derivative having 3 or more polymerizable groups and having a melting point of more than 40 ° C., the cross-linking reaction proceeds stably and sufficiently, and the cross-linking agent (B). ) Can suppress bleed-out, and can provide a crosslinked product having excellent heat-resistant water-resistant, heat-resistant solvent resistance and interlayer adhesion and high safety. Hereinafter, each component will be described.

<EVOH (A)>
EVOH (A) is the main component of the resin composition of the present invention. Here, EVOH (A) is a copolymer having an ethylene unit and a vinyl alcohol unit as the main structural unit.

The lower limit of the ethylene unit content of EVOH (A) (the ratio of the number of ethylene units to the total number of monomer units in EVOH (A)) is preferably 20 mol%, more preferably 22 mol%, still more preferably 24 mol%. .. On the other hand, the upper limit of the ethylene unit content of EVOH is preferably 60 mol%, more preferably 55 mol%, still more preferably 50 mol%. When the ethylene unit content of EVOH (A) is 20 mol% or more, the crosslinked product has excellent oxygen barrier properties and melt moldability under high humidity. Further, when the ethylene unit content of EVOH (A) is 60 mol% or less, the oxygen barrier property is excellent.

The lower limit of the saponification degree of EVOH (A) (the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in EVOH (A)) is preferably 80 mol%, more preferably 95 mol%, and more preferably 99 mol%. Is even more preferable. On the other hand, the upper limit of the saponification degree of EVOH (A) is preferably 100 mol%, more preferably 99.99 mol%.

When EVOH (A) is composed of a mixture of two or more types of EVOH having different ethylene unit contents, the average value calculated from the mixed mass ratio is taken as the ethylene unit content. In this case, the difference in ethylene unit content between EVOHs having the farthest ethylene unit contents is preferably 30 mol% or less. The difference in ethylene unit content is more preferably 20 mol% or less, further preferably 15 mol% or less. Similarly, when EVOH (A) is composed of a mixture of two or more types of EVOH having different saponification degrees, the average value calculated from the mixed mass ratio is taken as the saponification degree of the mixture. In this case, the difference in saponification degree is preferably 7% or less, more preferably 5% or less. When a crosslinked product obtained from a resin composition containing EVOH (A) is molded into a multi-layer structure, it is desired that the multi-layer structure has a well-balanced thermal moldability and oxygen barrier property at a higher level. In this case, EVOH having an ethylene unit content of 24 mol% or more and 34 mol% or less and a saponification degree of 99% or more and an ethylene unit content of 34 mol% or more and 50 mol% or less and a saponification degree of 99 % Or more of EVOH is preferably mixed so as to have a blending mass ratio of 60/40 to 90/10 and used as EVOH (A).

The ethylene unit content and saponification degree of EVOH (A) can be determined by a nuclear magnetic resonance (NMR) method.

The lower limit of the melt flow rate of EVOH (A) (based on JIS K 7210, measured value at a temperature of 210 ° C. and a load of 2160 g) is preferably 0.1 g / 10 minutes, more preferably 0.5 g / 10 minutes. 1 g / 10 minutes is more preferable, and 3 g / 10 minutes is particularly preferable. On the other hand, the upper limit of the melt flow rate of EVOH (A) is preferably 200 g / 10 minutes, more preferably 50 g / 10 minutes, further preferably 30 g / 10 minutes, particularly preferably 15 g / 10 minutes, and 10 g / 10 minutes. Is the most preferable. By setting the melt flow rate of EVOH (A) to a value in the above range, the melt-kneadability and melt-moldability of the obtained resin composition are improved.

EVOH (A) may also contain a small amount of units of other monomers other than the ethylene unit and the vinyl alcohol unit as the copolymerization unit, as long as the object of the present invention is not impaired. Examples of such a monomer include α-olefins such as propylene, 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene and 1-octene; itaconic acid, methacrylic acid, acrylic acid and maleine. Unsaturated carboxylic acids such as acids, salts thereof, partial or complete esters thereof, nitriles thereof, amides thereof, anhydrides thereof; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxyethoxy) silane, γ-methacryloxy Vinyl silane compounds such as propyltrimethoxysilane; unsaturated sulfonic acid or a salt thereof; unsaturated thiols; vinylpyrrolidones and the like can be mentioned.

Among the above other monomers, when EVOH (A) contains 0.0002 mol% or more and 0.2 mol% or less of a vinylsilane compound as a copolymerization component, the resin composition of the present invention containing EVOH (A) can be obtained. When a multilayer structure is obtained by coextrusion molding or co-injection molding together with a polymer to be a base material (for example, polyester), the consistency of melt viscosity with the polymer to be a base material can be improved. , A homogeneous molded product can be produced. As the vinylsilane compound, vinyltrimethoxysilane, vinyltriethoxysilane and the like are preferably used.

Further, in order to impart flexibility to EVOH (A), it is also preferable to modify EVOH by a conventionally known method. In this case, the oxygen permeation rate of EVOH (A) can be adjusted by adjusting the structure and amount of the cross-linking agent (B) described later and the method for producing EVOH.

<Crosslinking agent (B)>
The cross-linking agent (B) is a triazine derivative having 3 or more polymerizable groups and having a melting point of more than 40 ° C. Since the melting point of the cross-linking agent (B) exceeds 40 ° C., it becomes a solid under the temperature conditions that can be usually used as a packaging material, and bleed-out can be prevented. Further, since the cross-linking agent (B) has 3 or more polymerizable groups, a cross-linked product can be efficiently produced by irradiation with an active energy ray such as an electron beam. The crosslinked product thus obtained is hygienic, has excellent heat-resistant water-resistant and heat-resistant solvent properties, and is also excellent in interlayer adhesion when formed into a multilayer structure. In the present invention, when the cross-linking agent (B) does not show a clear melting point, the softening temperature can be used instead of the melting point, and those having a softening temperature exceeding 40 ° C. are also used as the cross-linking agent (B). Can be done. Further, those which do not show melting or softening in the region above 40 ° C. can also be used as the cross-linking agent (B).

As described above, the melting point of the cross-linking agent (B) exceeds 40 ° C. For the purpose of further suppressing bleed-out, the melting point or softening temperature of the cross-linking agent (B) is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and even more preferably 70 ° C. or higher. Further, for the purpose of facilitating mixing with EVOH, the melting point or softening temperature of the cross-linking agent (B) is preferably 200 ° C. or lower, more preferably 150 ° C. or lower, and 120 ° C. or lower. Is even more preferable. The boiling point and the thermal decomposition temperature of the cross-linking agent (B) are preferably 200 ° C. or higher, more preferably 240 ° C. or higher, and even more preferably 260 ° C. or higher. When the boiling point and the thermal decomposition temperature are high, the loss of the compound during melt kneading and melt molding is suppressed, and it becomes easy to obtain a sufficient crosslinking effect.

The polymerizable group of the cross-linking agent (B) is not limited as long as it can cause a cross-linking reaction with EVOH (A), and examples thereof include unsaturated hydrocarbon groups, carboxyl groups, epoxy groups, and isocyanate groups. Among these, unsaturated hydrocarbon groups are preferable because they can be easily crosslinked by active energy rays.

The unsaturated hydrocarbon group is not limited as long as it is a group having at least one of an ethylenically unsaturated bond and an acetylene unsaturated bond. Examples include a group, an alkynyl group, an alkadynyl group, and an alkatolynyl group. The unsaturated hydrocarbon group usually has 2 to 12 carbon atoms, preferably 2 to 10, more preferably 2 to 8, and even more preferably 3 to 8.

Examples of the alkenyl group include a linear alkenyl group such as a vinyl group, a propenyl group (allyl group), a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group and a decenyl group, and a 2-propenyl group. , 1-Methylpropenyl group, 2-methylpropenyl group and other branched chain alkenyl groups, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group and other cyclic alkenyl groups and the like.

Examples of the alkazienyl group include a linear alkazienyl group such as a pentadienyl group, a hexadienyl group, a heptadienyl group and an octadienyl group, a branched chain alkazienyl group such as a 1-methylpentadienyl group and a 2-methylpentadienyl group, and the like. Can be mentioned.

Examples of the alkatolynyl group include a linear alkatolynyl group such as a hexatrienyl group, a heptatrienyl group and an octatrienyl group, a branch of a 1-methylhexatrienyl group and a 2-methylhexatorienyl group. Examples thereof include a chain-like alcatrienyl group.

Examples of the arylalkenyl group include a phenylvinyl group and a phenylpropenyl group.

Examples of the alkynyl group include a linear alkynyl group such as a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptynyl group and an octynyl group, and a branched chain alkynyl group such as a 1-methylpropynyl group and a 2-methylbutynyl group. And so on.

Examples of the alkaziynyl group include a linear alkaziinyl group such as a pentadiynyl group, a hexadiynyl group, a heptadiynyl group and an octadiynyl group, and a branched chain alkaziyl group such as a 1-methylpentadiynyl group and a 2-methylhexadiynyl group. Nyl group is mentioned.

Examples of the alkatolynyl group include a linear alkatolynyl group such as a hexatriinyl group, a heptatriinyl group and an octatriinyl group, a branch of a 1-methylheptatriinyl group and a 2-methyloctatriinyl group. Examples thereof include a chain alkatriinyl group.

Among the above-mentioned polymerizable groups, a vinyl group or an alkenyl group having 3 to 8 carbon atoms or an alkazienyl group is preferable, a vinyl group or an alkenyl group having 3 to 6 carbon atoms is more preferable, and a vinyl group or an alkenyl group having 3 to 5 carbon atoms is more preferable. Groups are even more preferred. By using the polymerizable group of the cross-linking agent (B) as these specific groups, the cross-linking reaction with EVOH (A) can proceed smoothly and sufficiently. Further, in order to obtain a sufficient cross-linking effect, the cross-linking agent (B) needs to have 3 or more polymerizable groups. When the number of polymerizable groups is 2 or less, there is a problem that the heat-resistant water or heat-resistant solvent is insufficient, or the electron beam irradiation amount needs to be increased in order to obtain sufficient heat-resistant water or heat-resistant solvent. It may adversely affect the appearance and mechanical properties of industrial pipes.

A part or all of the hydrogen atom of the unsaturated hydrocarbon group may be substituted with a substituent containing a heteroatom. The hetero atom in this case may be an atom other than a carbon atom and a hydrogen atom, and examples thereof include a halogen atom, an oxygen atom, a sulfur atom, and a nitrogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like. Specific examples of the substituent containing the hetero atom include an alkoxy group, a halogen atom, a hydroxyl group, an oxygen atom (= O), a cyano group and the like. As the alkoxy group, an alkoxy group having 1 to 5 carbon atoms is preferable, a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group and a tert-butoxy group are preferable, and a methoxy group and an ethoxy group are preferable. Is more preferable.

The cross-linking agent (B) needs to be a triazine derivative. Since the cross-linking agent (B) has a thermally stable triazine structure, the heat resistance of the cross-linking agent (B) is significantly improved, and decomposition of the cross-linking agent (B) during melt kneading and melt molding is prevented. And the cross-linking level in the obtained cross-linked product can be made sufficient. The triazine basic skeleton includes three types, 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine, but from the viewpoint of thermal stability and positional symmetry of the cross-linking site. Is more preferably 1,3,5-triazine as the basic skeleton.

The cross-linking agent (B) preferably has the same number of carbonyl groups as the polymerizable group. The type of the carbonyl group is not particularly limited, and examples thereof include partial structures such as aldehydes, ketones, carboxylic acids, esters, amides, and enones. The carbonyl group has the effect of improving the compatibility between EVOH (A) and the cross-linking agent (B), the cross-linking reaction between the two can proceed smoothly and sufficiently, and bleed-out can be suppressed. The position of the carbonyl group in the cross-linking agent (B) is not particularly limited, but the triazine skeleton can be used from the viewpoint of improving the thermal stability of the cross-linking agent (B) and at the same time effectively improving the compatibility with EVOH (A). It is preferably included, for example, 1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trion structure.

Specific structures of the cross-linking agent (B) include, for example, a polymer of triallyl cyanurate, a polymer of triallyl isocyanurate, a polymer of trimetalyl isocyanurate and a polymer of trimetalyl isocyanurate. These cross-linking agents are thermally stable and have good cross-linking reaction efficiency with active energy rays and the like. It is also easy to obtain and economically excellent. Among these, trimetalyl isocyanurate is preferable because it is particularly excellent in cross-linking reaction efficiency, heat-resistant solvent resistance, and appearance of the obtained cross-linked product.

Triallyl cyanurates and triallyl isocyanurates have a melting point of 40 ° C. or lower and are liquid at 40 ° C., but can be made solid at 40 ° C. by oligomerizing or polymerizing them. Examples of the method for achieving these oligomerizations and polymerizations include a method of heat-treating in the presence of oxygen at an appropriate temperature (for example, 50 to 120 ° C.) for an appropriate period (for example, about 1 hour to 24 hours), and an organic radical. Examples thereof include a radical polymerization initiator such as an oxide and a method using ultraviolet rays. As these oligomers and polymers, those having a molecular weight of about 500 to 100,000, preferably about 2,000 to 50,000, are used, and commercially available products having such a molecular weight range can be used as they are. As long as the cross-linking agent (B) is substantially solid in the region above 40 ° C., it is the present invention that monomers such as triallyl cyanurate and triallyl isocyanurate having a melting point of 40 ° C. or lower are mixed. Although it is one aspect, uneven whitening can be further reduced by reducing the amount of monomers present as a liquid at 40 ° C.

The amount of the cross-linking agent (B) used in the resin composition of the present invention may be determined according to the degree of cross-linking required for the cross-linked product, but the lower limit thereof is 0.4 mass by mass with respect to 100 parts by mass of EVOH (A). It is necessary to have parts, 0.6 parts by mass is preferable, and 0.8 parts by mass is more preferable. The upper limit needs to be 10 parts by mass with respect to 100 parts by mass of EVOH (A), preferably 8 parts by mass, and more preferably 6 parts by mass. By setting the amount of the cross-linking agent (B) to be within the above range, the cross-linking of EVOH (A) can be sufficiently promoted, and a cross-linked product having excellent heat-resistant water-resistant, heat-resistant solvent resistance and interlayer adhesion can be obtained. can. In addition, when the crosslinked product is made into a film for retort or the like, the gas barrier property before and after the retort is excellent. If the amount of the cross-linking agent (B) used is larger than the above range, the interlayer adhesiveness may be deteriorated, or appearance defects such as gels, bumps and uneven whitening may occur.

<Hindered phenolic compound (C)>
The resin composition of the present invention may contain a hindered phenolic compound (C), if necessary. The hindered phenolic compound (C) has an ester bond or an amide bond. By containing the hindered phenolic compound (C) having an ester bond or an amide bond, the effect of stabilizing the viscosity with respect to EVOH (A) and the effect of preventing the generation of gel-like lumps during melt kneading and melt molding are excellent. become. Here, the hindered phenolic compound (C) is an organic compound containing at least one phenol group, and the aromatic moiety thereof is at least one directly adjacent to a carbon having a phenolic hydroxyl group as a substituent. Means an organic compound that is substituted at one position, preferably both positions. The substituent adjacent to the hydroxyl group is an alkyl radical appropriately selected from an alkyl group having 1 to 10 carbon atoms, preferably a tertiary butyl group.

The melting point of the hindered phenolic compound (C) is preferably 40 ° C. or higher. For the purpose of suppressing bleed-out, the melting point or softening temperature of the hindered phenolic compound (C) is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 70 ° C. or higher. For the same reason, the molecular weight of hindered phenol is preferably 200 or more, more preferably 400 or more, still more preferably 600 or more. Further, for the purpose of facilitating mixing with EVOH (A), the melting point or softening temperature of the hindered phenol compound (C) is preferably 200 ° C. or lower, more preferably 190 ° C. or lower, still more preferably 180 ° C. or lower. ..

The hindered phenolic compound (C) preferably has an amide bond. Since the hindered phenolic compound (C) has an amide bond, the effect of stabilizing the viscosity with respect to EVOH (A) and the effect of preventing the generation of gel-like lumps during melt kneading and melt molding are particularly excellent.

Specific structures of the hindered phenolic compound (C) include, for example,
-Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] marketed as Irganox 1010 from BASF.
Stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate marketed as Irganox 1076 ・ 2,2'-thiodiethylbis [3- (3,5-di-thiodiethylbis) marketed as Irganox 1035 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
-Commercially available as Irganox 1135 3- (3,5-di-)
1514280176025_0
-4-Hydroxyphenyl)
1514280176025_1
Ethylene bis (oxyethylene) commercially available as octadecyl ilganox 245 bis (3-tert-butyl-4-hydroxy-5-methylbenzenepropanoic acid)
1,6-Hexanediol bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] marketed as Irganox 259]
N, N'-hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanamide] commercially available as Irganox 1098]
Among these, N, N'-hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl), which is commercially available as Irganox 1098 because it has an amide bond. Propanamide] is preferred.

The amount of the hindered phenolic compound (C) used in the resin composition of the present invention may be determined according to the conditions at the time of melt kneading and melt molding, and the lower limit thereof is with respect to 100 parts by mass of EVOH (A). 0.05 parts by mass is preferable, 0.2 parts by mass is more preferable, and 0.4 parts by mass is further preferable. The upper limit is preferably 10 parts by mass, more preferably 5 parts by mass, and even more preferably 3 parts by mass with respect to 100 parts by mass of EVOH (A). By setting the amount of the hindered phenol compound (C) to be in the above range, it is possible to prevent excessive cross-linking due to the cross-linking agent (B) during melt kneading and melt molding, and to maintain a stable viscosity for a long period of time. Can be maintained. Further, since it is possible to prevent the generation of gel-like lumps during melt kneading and melt molding, it is possible to produce a crosslinked product having an excellent appearance.

<Other ingredients>
The resin composition of the present invention may contain other components as long as the effects of the present invention are not impaired. Examples of other components include boron compounds, alkali metal salts, phosphoric acid compounds, substances that can be oxidized, other polymers, oxidation accelerators, and other additives.

<Boron compound>
When a boron compound is added to the resin composition of the present invention, it is effective in that the melt viscosity of EVOH is improved and a homogeneous coextruded or co-injected molded product can be obtained. Examples of the boron compound include boric acids, borate esters, borates, and boron hydrides. Specifically, examples of boric acids include orthoboric acid (hereinafter, also simply referred to as "boric acid"), metaboric acid, tetraboric acid and the like, and examples of boric acid esters include triethyl borate, trimethyl borate and the like. Examples of the borate include alkali metal salts of the above-mentioned various boric acids, alkaline earth metal salts, boric acid and the like. Among these compounds, orthoboric acid is preferable.

When a boron compound is added, the content in the composition is preferably 20 to 2000 ppm, more preferably 50 to 1500 ppm in terms of elemental boron. Within this range, it is possible to obtain EVOH in which torque fluctuation during heating and melting is suppressed. If it is less than 20 ppm, such an effect is small, while if it exceeds 2000 ppm, gelation is likely to occur and moldability may be poor.

<Alkali metal salt>
The resin composition of the present invention preferably contains an alkali metal salt in an alkali metal element equivalent of 5 to 5000 ppm, more preferably 20 to 1000 ppm, still more preferably 30 to 500 ppm. By containing the alkali metal salt in the above range, the interlayer adhesiveness and compatibility can be improved. Examples of the alkali metal include lithium, sodium, potassium and the like, and examples of the alkali metal salt include an aliphatic carboxylate of an alkali metal, an aromatic carboxylate, a phosphate, a metal complex and the like. For example, sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salts of ethylenediamine tetraacetic acid and the like can be mentioned, and among these, sodium acetate, potassium acetate and sodium phosphate are preferable.

<Phosphoric acid compound>
The resin composition of the present invention preferably contains a phosphoric acid compound at 1 to 500 ppm in terms of phosphoric acid root, more preferably 5 to 300 ppm, still more preferably 10 to 200 ppm. By blending the phosphoric acid compound in the above range, the thermal stability of EVOH can be improved. In particular, it is possible to suppress the generation and coloring of gel-like lumps during long-term melt molding.

The type of the phosphoric acid compound added to the resin composition of the present invention is not particularly limited, and for example, various acids such as phosphoric acid and phosphorous acid and salts thereof can be used. The phosphate may be in the form of a first phosphate, a second phosphate, or a third phosphate. The cation species of the phosphate is not particularly limited, but it is preferable that the cation species is an alkali metal or an alkaline earth metal. Above all, it is preferable to add the phosphorus compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate.

<Other additives>
The resin composition of the present invention may contain various additives as long as the effects of the present invention are not impaired. Examples of such additives include plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, UV absorbers, antistatic agents, lubricants, colorants, fillers, desiccants, fillers, etc. Examples thereof include pigments, dyes, processing aids, flame retardants, antifogging agents, antioxidants other than compound (C), and the like.

<Manufacturing method of resin composition>
The method for producing a resin composition of the present invention is a copolymerization step of copolymerizing ethylene and vinyl ester to obtain an ethylene-vinyl ester copolymer, and saponifying the ethylene-vinyl ester copolymer to make EVOH (A). Includes a saponification step of obtaining a mixture and a mixing step of mixing EVOH (A) and a cross-linking agent (B) to obtain a mixture.

In the copolymerization step, in addition to the step of copolymerizing ethylene and vinyl ester, a polymerization inhibitor is added as necessary, and then unreacted ethylene and unreacted vinyl ester are removed to remove ethylene-vinyl ester copolymer weight. Includes the step of obtaining a coalesced solution. Examples of the copolymerization method of ethylene and vinyl ester include known methods such as solution polymerization, suspension polymerization, emulsion polymerization and bulk polymerization.

Vinyl acetate is mentioned as a typical vinyl ester used for polymerization, but other aliphatic vinyl esters such as vinyl propionate and vinyl pivalate can also be used. In addition, a small amount of copolymerizable monomers can be copolymerized.

The polymerization temperature is preferably 20 to 90 ° C, more preferably 40 to 70 ° C. The polymerization time is preferably 2 to 15 hours, more preferably 3 to 11 hours. The polymerization rate is preferably 10 to 90%, more preferably 30 to 80% with respect to the charged vinyl ester. The resin content in the solution after the polymerization is preferably 5 to 85% by mass, more preferably 20 to 70% by mass.

In the saponification step, an alkaline catalyst is added to the ethylene-vinyl ester copolymer solution to saponify the copolymer in the solution. The saponification method can be either continuous or batch. Examples of the alkali catalyst include sodium hydroxide, potassium hydroxide, and alkali metal alcoholate.

In the mixing step, it is preferable to add EVOH (A), a cross-linking agent (B), and if necessary, a hindered phenolic compound (C), and then melt-knead. At this time, it can be carried out by using a known mixing device or kneading device such as a kneader ruder, an extruder, a mixing roll, and a Banbury mixer. The temperature at the time of melt-kneading is usually 110 to 300 ° C. The hindered phenolic compound (C) may be contained in EVOH (A) or a cross-linking agent (B) in advance.

<Manufacturing method of crosslinked product>
In the mixture, EVOH (A) is cross-linked by the cross-linking agent (B) by applying energy from the outside (cross-linking step). This cross-linking is preferably carried out by irradiating or heating at least one active energy ray selected from the group consisting of electron beams, X-rays, γ-rays, ultraviolet rays and visible rays. Among these, when irradiating with active energy rays, cross-linking can be performed only by irradiating with active energy rays, so that a special extruder or the like is not required, and a cross-linked product can be manufactured easily and at low cost. be able to. Among the active energy rays, it is preferable to carry out cross-linking with the above-mentioned electron beam from the viewpoint of cross-linking speed and cross-linking efficiency. This makes it possible to efficiently produce a crosslinked product having low bleed-out property, good heat resistance and water resistance, heat resistance solvent property, and interlayer adhesion.

When electron beam, X-ray or γ-ray is used, the absorbed dose is preferably 1 kGy or more, more preferably 1 kGy to 1 MGy, further preferably 5 kGy to 500 kGy, and particularly preferably 10 kGy to 200 kGy. If the absorbed dose is less than 1 kHz, the degree of cross-linking does not improve, and the desired performance such as heat resistant water and heat resistant solvent may not be obtained. Further, when the absorbed dose is larger than 1 MGy, decomposition of EVOH or the like may occur, and problems such as deterioration of mechanical strength and coloring when the crosslinked product is made into a film may occur.

When light irradiation is used, the irradiation time is affected by the thickness of the crosslinked product, the type of light source, and other conditions, but high-pressure mercury lamps, low-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, LEDs, etc. are used. It may be as long as several minutes, usually within one minute, and in some cases less than one second.

The cross-linking step of the resin composition of the present invention may be determined according to the properties of the target molded product, and may be before or after molding. In particular, considering the degree of freedom in molding the resin composition, it is preferable to carry out cross-linking after molding.

<Molding method for crosslinked products>
In molding the resin composition of the present invention, various molded products such as films, sheets, containers and other packaging materials can be molded by appropriately adopting a molding method. At this time, the resin composition may be once pelletized and then subjected to molding, or each component of the resin composition may be dry-blended and subjected to direct molding.

As the molding method and the molded product, for example, it can be molded into a film, a sheet, a pipe or the like by melt extrusion molding, into a container shape by injection molding, or into a hollow container such as a bottle by hollow molding. Examples of hollow molding include extrusion hollow molding in which a parison is formed by extrusion molding and then blown to form the preform, and injection hollow molding in which a preform is formed by injection molding and then blown to form the preform. can. Of these, as the packaging material for retort pouches, a method of forming a packaging material such as a multilayer film by melt extrusion molding and a method of thermoforming a multilayer sheet formed by melt extrusion molding into a container-shaped packaging material are preferable. Further, depending on the application, a method of forming a parison by extrusion molding and blow molding the parison to form a relatively flexible multi-layer container-shaped packaging material is also preferable.

<Multi-layer structure>
The crosslinked product has a wide range of uses. For example, extruded products, films or sheets (especially stretched films or heat shrink films), heat molded products, wallpaper or veneer, pipes or hoses, profiled products, extruded blow molded products, injection molded products, flexible packaging materials, containers. (Especially a retort container) and the like are exemplified as suitable ones. When the molded product is a multi-layer structure, co-extruded film or co-extruded sheet, heat-shrinkable film, container (especially co-extruded blow molded container, co-injection molded container, retort container), pipe (especially fuel pipe or hot water circulation). Pipes), hoses (particularly fuel hoses) and the like are preferred.

The multilayer structure is obtained by laminating a layer of a crosslinked product obtained by the above molding and another layer.

As the layer structure of the multilayer structure, when the layer made of a polymer other than the resin composition of the present invention is the x layer, the resin composition layer of the present invention is the y layer, and the adhesive polymer layer is the z layer, x / y, x / y / x, x / z / y, x / z / y / z / x, x / y / x / y / x, x / z / y / z / x / z / y / z / X and the like are exemplified. When a plurality of x layers are provided, the types may be the same or different. Further, a layer using a recovered polymer made of scrap such as trim generated during molding may be separately provided, or the recovered polymer may be blended with a layer made of another polymer. The thickness composition of each layer of the multilayer structure is not particularly limited, but the thickness ratio of the y layer to the total layer thickness is preferably 2 to 20% from the viewpoint of moldability and cost.

As the polymer used for the x-layer, a thermoplastic polymer is preferable from the viewpoint of processability and the like. Examples of such thermoplastic polymers include the following polymers.
-Polymer, polypropylene, ethylene-propylene copolymer, ethylene or propylene copolymer (polymer of ethylene or propylene and at least one of the following monomers: 1-butene, isobutene, 4-methyl-1- Α-olefins such as penten, 1-hexene and 1-octene; unsaturated carboxylic acids such as itaconic acid, methacrylic acid, acrylic acid and maleic anhydride, salts thereof, partial or complete esters thereof, nitriles thereof, amides thereof, and amides thereof. Anhydrous: Carboxylic acid vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, vinyl dodecanoate, vinyl stearate, vinyl arachidonate; vinyl silanes such as vinyl trimethoxysilane Compounds; unsaturated sulfonic acids or salts thereof; alkylthiols; vinylpyrrolidones, etc.);
-Polyolefins such as poly4-methyl-1-pentene and poly1-butene;
-Polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate;
-Polyamides such as polyε-caprolactam, polyhexamethylene adipamide, polymethoxylylen adipamide;
-Polyvinylidene chloride, polyvinyl chloride, polystyrene, polyacrylonitrile, polycarbonate, polyacrylate, etc.
The thermoplastic polymer layer may be unstretched, or may be uniaxially or biaxially stretched or rolled. Among these polymers, when used in a retort container, it is preferable that the outer layer side of the package when food or the like is packaged is polyamide, polyester, or polypropylene. The inner layer side is preferably polypropylene. Further, when it is used for an industrial pipe having a y layer as an intermediate layer, it is preferable that both the inner layer side and the outer layer side are polyethylene or polypropylene.

Among these thermoplastic polymers, polyolefin is preferable in terms of moisture resistance, mechanical properties, economy, heat sealability, etc., and polyamide and polyester are preferable in terms of mechanical properties, heat resistance, and the like.

On the other hand, the adhesive polymer used for the z layer may be any adhesive polymer capable of adhering between the layers, and is a polyurethane-based or polyester-based one-component or two-component curable adhesive, or a carboxylic acid-modified polyolefin polymer. Etc. are preferable. The carboxylic acid-modified polyolefin polymer is an olefin-based polymer or copolymer containing an unsaturated carboxylic acid or an anhydride thereof (maleic anhydride, etc.) as a copolymer; or an unsaturated carboxylic acid or an anhydride thereof in an olefin-based weight. It is a graft copolymer obtained by grafting on a coalescence or a copolymer.

When a multilayer structure is produced by a co-injection molding method, a co-extrusion molding method, or the like, a carboxylic acid-modified polyolefin polymer is more preferable. In particular, when the x layer is a polyolefin polymer, the adhesiveness with the y layer is good. Examples of the polyolefin polymer constituting such a carboxylic acid-modified polyolefin polymer include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (VLDPE); polypropylene; copolymerization. Polypropylene; ethylene-vinyl acetate copolymer; ethylene- (meth) acrylic acid ester (methyl ester or ethyl ester) copolymer and the like can be mentioned. On the other hand, when a multilayer structure is produced by the dry laminating method, a polyurethane-based two-component curable adhesive is more preferable. In this case, since various polymers can be used for the x layer, the function of the multilayer structure can be further enhanced.

Examples of the method for obtaining the multilayer structure of the present invention include an extrusion laminating method, a dry laminating method, a co-injection molding method, a co-extrusion molding method and the like. Examples of the co-extrusion molding method include a co-extrusion laminating method, a co-extrusion sheet molding method, a co-extrusion pipe molding method, a co-extrusion tube molding method, a co-extrusion inflation molding method, a co-extrusion blow molding method and the like.

The sheet, film, parison, etc. of the multilayer structure of the present invention thus obtained are reheated at a temperature equal to or lower than the melting point of the contained polymer, and are subjected to a thermoforming method such as draw molding, a roll stretching method, and a pantograph. It is also possible to obtain a stretched molded product by uniaxially or biaxially stretching by a formula stretching method, an inflation stretching method, a blow molding method or the like.

The multilayer structure of the present invention can be applied to various uses, for example, it can be used for the uses exemplified in the above-mentioned crosslinked product. Above all, it is preferable to use it for a retort container or a pipe in order to take advantage of the low bleed-out property of the cross-linking agent of the multilayer structure, good heat resistance and water resistance, heat resistant solvent property and interlayer adhesion. It can also be suitably applied as a container for chemically active chemicals and pesticides. Hereinafter, an embodiment in which the multilayer structure of the present invention is used as a retort container will be described.

By using the multi-layer structure of the present invention, it is possible to obtain a flexible retort container made of a thin multi-layer structure having a total thickness of all layers (hereinafter, also simply referred to as “total layer thickness”) of 300 μm or less. can. Usually, such a flexible retort container is processed into a pouch or the like. This container is excellent in oxygen barrier property, heat resistance and water resistance, and easy to manufacture, and is therefore useful for packaging products that are highly sensitive to oxygen and easily deteriorate.

From the viewpoint of maintaining flexibility, the upper limit of the total layer thickness of such a multilayer film is preferably 300 μm, more preferably 250 μm, and even more preferably 200 μm. On the other hand, considering the mechanical properties of the container, the lower limit of the total layer thickness is preferably 10 μm, more preferably 20 μm, and even more preferably 30 μm.

The retort container made of a multilayer film having a total layer thickness of 300 μm or less can be obtained, for example, by laminating a layer made of the resin composition of the present invention and a thermoplastic resin layer by a method such as dry laminating or coextrusion laminating. It can be manufactured from a multilayer film.

In the case of producing from a multilayer film obtained by dry laminating, a non-stretched film, a uniaxially stretched film, a biaxially stretched film, a rolled film and the like can be used as the multilayer film. Among these, biaxially stretched polypropylene film, biaxially stretched polyester film, and biaxially stretched polyamide film are preferable from the viewpoint of mechanical strength and heat resistance. When a non-stretched film or a uniaxially stretched film is used, the multilayer film is reheated after laminating and uniaxially or biaxially stretched by a thermoforming method such as draw forming, a roll stretching method, a pantograph stretching method, an inflation stretching method, or the like. Thereby, a stretched multilayer film can also be obtained.

In order to seal the obtained retort container, it is also preferable to provide a layer made of a heat-sealable resin on the surface of at least one of the outermost layers in the manufacturing stage of the multilayer film. Examples of such a resin include polyolefins such as polyethylene and polypropylene.

The retort container thus obtained is excellent in safety, flexible and convenient, and has excellent oxygen barrier properties, and is therefore useful for packaging contents that are easily deteriorated by the presence of oxygen, especially foods, pet foods, pharmaceuticals, and the like. ..

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. Here, the quantitative relationship is based on mass unless otherwise specified. Each measurement / evaluation in Examples and Comparative Examples was performed as follows.

(1) Gel fraction The pellets of the resin composition obtained in the following examples and comparative examples are passed through a 20 mmφ uniaxial extruder (210 ° C.) and melt-extruded from a coated hanger die to obtain a single layer having a thickness of 20 μm. I got a film. The obtained single-layer film was introduced into an electron beam irradiation device and irradiated with an electron beam at an acceleration voltage of 250 kV for cross-linking to obtain an irradiated single-layer film. Next, the obtained irradiated single-layer film was cut out in a 20 cm square. 1 part by mass of the irradiated single layer film is immersed in 100 parts by mass of a mixed solvent of water (15% by mass) and phenol (85% by mass), heated and dissolved at 60 ° C. for 12 hours, filtered, and the filtrate is evaporated to dryness. The solid content residue (%) was calculated by solidification, and this was used as the gel content.

(2) Heat-resistant water (evaluation of single-layer film)
The irradiated single-layer film obtained in the same manner as in (1) above was cut into 10 cm squares, sealed in a 12 cm square pouch with 100 ml of water, and retort-treated at 135 ° C. for 60 minutes, and the appearance of the film was visually observed. .. The appearance of the film at that time was evaluated according to the following criteria.
A: Overall, the film did not dissolve.
B: Part of the film was dissolved.
C: The film was melted as a whole and did not retain its original shape.

(3) Heat-resistant water-based (evaluation of multilayer film)
Takelac A-520 and Takenate manufactured by Mitsui Chemicals, Inc. on both sides of a single-layer film (before electron beam irradiation) obtained by forming a stretched polyamide film (ON) and a non-stretched polypropylene film (CPP) in the same manner as in (1) above. By laminating via a polyurethane-based two-component curable adhesive (Ad) made of A-50, a multilayer film ((outer layer) ON 15 μm / Ad / EVOH layer (single layer film) 20 μm / Ad / CPP 50 μm) (Inner layer)) was obtained. The obtained multilayer film was introduced into an electron beam irradiator and irradiated with an electron beam at an acceleration voltage of 250 kV for cross-linking to obtain an irradiated multilayer film. Using the obtained irradiation multilayer film, a 10 cm square pouch was prepared, 80 ml of water was poured into the pouch, and the pouch was visually observed after being retorted at 135 ° C. for 60 minutes. The appearance of the pouch at that time was evaluated according to the following criteria.
A: No peeling between the EVOH layer and the inner and outer layers was confirmed, and the transparency of the EVOH layer was maintained.
B: Peeling was observed between the EVOH layer and a part of the inner and outer layers, or slight whitening was observed in the EVOH layer.
C: Peeling was observed in most of the EVOH layer and the inner and outer layers, or remarkable whitening was observed in the EVOH layer.

(4) Heat-resistant solvent resistance 1 ml of glycerol was dropped onto the irradiated single-layer film obtained in the same manner as in (1) above, the film was folded to sandwich the glycerol, and a load of 1 kg was applied thereto. In this state, heat treatment was performed at 100 ° C. for 30 minutes. After cooling to room temperature, the degree of stickiness and appearance (whitening or uneven whitening) of the film were visually observed. The degree of stickiness and appearance of the film at that time were evaluated according to the following criteria.
A: No stalemate or change in appearance was observed.
B: Slight stalemate and change in appearance were observed.
C: Slight stalemate and change in appearance were observed.

(5) OTR (oxygen permeation rate; before retort)
Using the irradiation multilayer film obtained in the same manner as in (3) above, OTR was measured under the following conditions.
Conditions: 20 ° C, (outside) 65% RH / (inside) 100% RH

(6) OTR (oxygen permeation rate; after retort)
An irradiation multilayer film obtained in the same manner as in (3) above was used to prepare a pouch, water was poured into the pouch, and the OTR was retorted at 135 ° C. for 60 minutes, and then the OTR was measured under the following conditions.
Conditions: 20 ° C, (outside) 65% RH / (inside) 100% RH, 1 day after retort

(7) Laminate Adhesiveness The irradiated single-layer film obtained in the same manner as in (1) above is stored at 40 ° C. and 90% RH for 3 months, and then a polyurethane-based two-component curable adhesive is used. It was laminated with a CPP film (50 μm). After aging this at 40 ° C. for 2 days, the adhesiveness was evaluated.
A: Adhesiveness is good, and it does not peel off even if force is applied.
B: Adhesive is good, but it may peel off when force is applied.
C: No peeling is seen in normal use, but peeling occurs when force is applied.

(8) Appearance characteristics The appearance characteristics are evaluated by visually confirming the amount of gel and lumps generated and the uneven whitening of the irradiated single-layer film obtained in the same manner as in (1) above, and evaluating them according to the following criteria A to D. It was used as an index. Criterion C is a border level that can withstand actual use.
A: Almost no gel, lumps and uneven whitening B: Slight gel, lumps and uneven whitening C: Slightly gel, lumps and uneven whitening D: Significant gel, lumps and uneven whitening

The ethylene-vinyl alcohol copolymer (A), the cross-linking agent (B) and the hindered phenolic compound (C) used in each example are shown below.
<Ethylene-vinyl alcohol copolymer (A)>
(EVOH-1) Ethylene unit content: 27 mol%, saponification degree: 99.8%
(EVOH-2) Ethylene unit content: 44 mol%, saponification degree: 99.8%

<Crosslinking agent (B)>
(Crosslinking agent 1) Tyke prepolymer manufactured by Nihon Kasei Co., Ltd. Triallyl isocyanurate polymer: Pyrolysis started at 200 ° C without melting or softening.
(Crosslinking agent 2) Trimetharyl isocyanurate: Melting point 84 ° C.
(Crosslinking agent 3) Triallyl cyanurate: Melting point 27 ° C.
(Crosslinking agent 4) Triallyl isocyanurate: Melting point 25 ° C.
(Crosslinking agent 5) Trimethylolpropane Trimethacrylate (crosslinking agent other than triazine derivative): Melting point -14 ° C.
(Crosslinking agent 6) Pentaerythritol triallyl ether (crosslinking agent other than triazine derivative): melting point of about -20 ° C.

<Hindered phenolic compound (C)>
(Hinderd Phenol Compound 1) BASF's Irganox 1010 Pentaerythritol Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
(Hindered Phenol Compound 2) BASF's Irganox 1098 N, N'-hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanamide]

(Examples 1 to 10 and Comparative Examples 1 to 8)
A pellet of a crosslinkable resin composition was prepared by melt-kneading the above-mentioned EVOH, a cross-linking agent and a hindered phenol-based compound at 210 ° C. using a 25 mmφ twin-screw extruder at the ratios shown in Table 1. The irradiation dose of the electron beam in each measurement / evaluation is 10 kGy in Example 9, no irradiation in Comparative Example 1, and 100 kGy in the other Examples and Comparative Examples. The evaluation results are shown in Table 2.

As is clear from the results in Table 2, in each film obtained by using the resin composition of the example, the gel fraction was high and the cross-linking proceeded sufficiently. As a result, each film of the example was excellent in heat-resistant water-resistant and heat-resistant solvent resistance, had a low OTR value, and maintained good interlayer adhesiveness. On the other hand, the film obtained by using the resin composition of the comparative example was inferior in any of heat-resistant water-resistant, heat-resistant solvent resistance, OTR, interlayer adhesiveness, and appearance characteristics. Further, in the examples in which the hindered phenolic compound was appropriately added, the viscosity at the time of melt kneading and melt molding was stable, and the appearance of the obtained crosslinked product was also good. In particular, in the examples using the hindered phenolic compound having an amide bond, the appearance characteristics of the obtained crosslinked product were excellent.

The resin composition of the present invention can sufficiently suppress the bleed-out of the cross-linking agent from the cross-linked product, and can realize a cross-linked product having excellent heat-resistant water-resistant, heat-resistant solvent resistance and interlayer adhesion and being hygienic. , Food packaging materials and other packaging materials and industrial pipes can be suitably used. Further, since the EVOH (A) used is not particularly limited, it is possible to form various crosslinked products.

Claims (11)

A resin composition containing 0.4 to 10 parts by mass of the cross-linking agent (B) with respect to 100 parts by mass of the ethylene-vinyl alcohol copolymer (A), wherein the cross-linking agent (B) is trimetalyl isocyanurate . Resin composition. The resin composition according to claim 1, further comprising 0.05 to 10 parts by mass of the hindered phenolic compound (C) having an ester bond or an amide bond with respect to 100 parts by mass of the ethylene-vinyl alcohol copolymer (A). thing. The resin composition according to claim 2 , wherein the hindered phenolic compound (C) has an amide bond. The resin composition according to any one of claims 1 to 3 , which is used for active energy ray cross-linking. A crosslinked product obtained from the resin composition according to any one of claims 1 to 4 . A film made of the crosslinked product according to claim 5 . A multilayer structure having a layer made of the crosslinked product according to claim 5 . The retort container having the multilayer structure according to claim 7 . The pipe having the multilayer structure according to claim 7 . Copolymerization step of copolymerizing ethylene and vinyl ester to obtain an ethylene-vinyl ester copolymer,
A saponification step of saponifying the ethylene-vinyl ester copolymer to obtain an ethylene-vinyl alcohol copolymer (A), and a mixture of the ethylene-vinyl alcohol copolymer (A) and a cross-linking agent (B). Including the mixing step to obtain,
The method for producing a resin composition according to any one of claims 1 to 4 . Copolymerization step of copolymerizing ethylene and vinyl ester to obtain an ethylene-vinyl ester copolymer,
A saponification step of saponifying the ethylene-vinyl ester copolymer to obtain an ethylene-vinyl alcohol copolymer (A).
A claim comprising a mixing step of mixing an ethylene-vinyl alcohol copolymer (A) and a crosslinking agent (B) to obtain a mixture, and a crosslinking step of irradiating the mixture obtained in the mixing step with active energy rays. Item 5. The method for producing a crosslinked product according to Item 5.