JP2647442B2 - Gas barrier multilayer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a laminated multilayer body in which gas barrier properties are hardly reduced even under extremely severe bending fatigue. Specifically, a thin layer of a saponified ethylene-vinyl acetate copolymer resin (hereinafter referred to as EVOH), which has excellent gas barrier properties against oxygen and carbon dioxide gas, is an essential constituent layer, and at least one of the layers has a specific structure. The present invention relates to a multilayer body in which a surface layer is laminated via an agent layer. More specifically, the present invention provides a laminated multilayer body that can maintain gas barrier properties even against extremely severe bending fatigue that a packaging material undergoes during transportation and handling, and that is effective for preventing deterioration of an object to be packaged.

(Prior art) The function of laminated packaging materials is basically
That is, it is required to prevent deterioration, and therefore, the packaging material is required to have particularly high vibration strength during transportation and to have bending fatigue resistance. When used as an inner container of a so-called bag-in-box-a container combining a thin-walled inner container of a foldable plastic and an outer cardboard box having stackability, portability, and printability, the above-mentioned advanced properties are required. Is done. The packaging material is used by laminating various plastic films utilizing the properties of the respective materials. For example, the most common combination is a combination of a base film for maintaining mechanical strength and a heat sealable material. The material is selected according to the request of the packaged item. In particular, in the gas barrier properties such as oxygen of the base film,
For unsatisfactory applications, a barrier layer having a higher gas barrier property is provided on the base material layer, and a heat-sealable material is formed by using the barrier layer as an intermediate layer and a thermoplastic resin layer as at least one outer layer. A lamination method is employed. For example, the material of the inner container of the conventional bag-in-box is basically made of heat-sealable polyethylene, especially soft polyethylene, because there is always a heat-sealed part, but it must be foldable, which is a feature of the bag-in-box. Since the contents are liquid, physical strength is required, especially as mentioned above, especially transport vibration strength and bending fatigue resistance, and this is combined with good stress crack resistance. And ethylene-vinyl acetate copolymer resin are more preferably used. In the case where gas barrier properties such as oxygen are required in accordance with the sophistication of required performance, the inner container that combines nylon film, Saran coated nylon film, aluminum-deposited nylon film, aluminum-deposited polyester film, etc. is put into practical use. Is starting to be. In order to provide high gas barrier properties, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride,
An aluminum foil, a vapor-deposited film of metal or the like is used.
However, although they are excellent in gas barrier properties, they generally have low mechanical strength and are not particularly resistant to bending fatigue. Therefore, it is used by being laminated between a base layer having excellent mechanical strength and a heat-sealable material. However, when used as a component of a bag-in-box inner container, for example, a pinhole is generated in the component. Even at the stage where no pinholes are formed in the constituent material, the barrier property is deteriorated due to cracks and pinholes generated in the barrier layer used as an essential constituent layer. On the other hand, excellent gas barrier properties cannot be maintained, and no practically satisfactory one has been found. The behavior of a laminated packaging material having a barrier layer made of a layer mainly composed of polyvinylidene chloride resin, a vapor-deposited resin layer of aluminum foil, metal or the like is shown in, for example, JP-A-55-7747. That is, the actual use of the packaging material, the transportation of the packaged package, the gas barrier properties after handling is not always satisfactory, and the most necessary practical preservation after primary distribution is often betrayed. , Due to damage to the barrier layer.

JP-A-50-86579 discloses a polyolefin resin layer and an EVOH layer, and at least one of the layers comprises ethylene-
It describes a package in which an acrylate copolymer is added and both layers are firmly adhered to each other.
No. 162 describes a laminate in which a polyethylene layer or an ethylene-vinyl acetate copolymer layer is laminated on a layer in which an ethylene-vinyl acetate copolymer is mixed with EVOH, and the two are firmly adhered to each other.

Furthermore, Japanese Patent Application Laid-Open No. 60-161146 describes that by providing a linear low-density polyethylene layer on both sides of an EVOH layer, a packaging material having excellent bending fatigue resistance can be obtained.

(Problems to be Solved by the Invention) While EVOH film has the above-mentioned excellent characteristics,
Compared to films of thermoplastic resins such as polyethylene, polypropylene, nylon, and thermoplastic polyester, it has a major drawback of being extremely poor in bending fatigue resistance.
Laminated with the resin layer resistant to bending fatigue, as an essential constituent layer
In a multilayered multilayer body using an EVOH resin layer, the bending fatigue resistance of the packaging material is significantly lower than the bending fatigue resistance of the thermoplastic resin strong in bending fatigue, and the bending fatigue resistance is smaller. Pinholes occur in the laminated packaging.

The present inventors have improved the bending fatigue resistance of the multilayer multilayer body including the EVOH layer without deteriorating its excellent gas barrier properties, and developed a flexible multilayer multilayer body having excellent bending fatigue resistance and gas barrier properties. The present inventors have made intensive studies to complete the present invention.

(Means for Solving the Problems) That is, the present invention provides an ethylene component content of 20 to 55 mol%,
In a multilayer body composed of a layer of a saponified ethylene-vinyl acetate copolymer having a degree of saponification of 90% or more and a layer of a resin, an adhesive mainly comprising a polymer containing a structural unit represented by the following formula (I) as an intermediate layer: It is a gas barrier multilayer body characterized by interposing an agent.

−OCH ₂ CH (CH ₃ ) (CH ₂ ) ₆ O− (I) The evaluation of flex fatigue resistance of various materials or laminated materials composed of various materials is performed using a so-called gel boflex tester. Can be determined from data such as the dependence of the decrease in gas barrier property on the number of bendings and the number of bendings before pinholes occur. The present inventors have investigated the number of bending times using a gel boflex tester for a single film of various thermoplastic resins, a laminated film having a multilayer structure composed of various resins, particularly for a laminated film in which an adhesive used between the respective layers is different. The relationship between the number of pinholes generated, the number of bends that lead to the occurrence of pinholes, and, for a multilayer laminate, the relationship between the number of bends and the barrier properties (for example, the amount of oxygen permeation) in the process leading to the occurrence of pinholes is varied. As a result of measuring over
I found some facts. That is, (1) the EVOH resin films have extremely poor bending fatigue resistance, which is far below the level of transport vibration strength that can withstand practical use;
(2) Conventionally used films of each resin such as high-pressure method low-density polyethylene, low-pressure method high-density polyethylene, nylon, polypropylene, thermoplastic polyester and the like have a lower bending fatigue resistance than the EVOH resin film. Although the flexural fatigue resistance of the laminated film obtained by laminating the resin film with EVOH as an intermediate layer is not clear, although it is remarkably excellent, a remarkable decrease due to the presence of the EVOH layer, that is, the resin The remarkable decrease is seen compared to the excellent bending fatigue resistance of the single film,
(3) Even more surprisingly, there is almost no decrease in gas barrier property until the occurrence of pinholes in the laminate having the EVOH layer as an intermediate layer. Layer, both surface layers are provided via an adhesive, but the laminate laminated using a polyurethane-based adhesive having a specific structural unit has remarkable bending fatigue resistance developed when EVOH is used as an intermediate layer. The decrease was alleviated, and it was recognized that the bending fatigue resistance of the laminate was significantly improved. That is, the present invention has found out that the specific adhesive is very strongly related to the bending fatigue resistance of the EVOH layer.

(Detailed Description of the Invention) The present invention has an ethylene content of 20 to 55 mol% and a degree of saponification.
In a multilayer body comprising a layer of a saponified ethylene-vinyl acetate copolymer of 90% or more and a layer of a resin, an adhesive mainly comprising a polymer containing a structural unit represented by the following formula (I) as an intermediate layer: A gas barrier multilayer body characterized by interposing

—OCH ₂ CH (CH ₃ ) (CH ₂ ) ₆ O— (I) Examples of the polymer containing a structural unit represented by the above formula (I) in a molecule used in the present invention include polyester-based polymers,
Polyester polyurethane, polycarbonate and the like are often used. Among them, polyester-based, polyester-polyurethane-based, and further, polyester-polyurethane-based are often used more preferably.

In the case where the polymer is polyester, if dicarboxylic acid and 2-methyl-1,8-octyldiol alone are required, they may be copolymerized with other polyfunctional polyols or polycarboxylic acids. And polyester polyols obtained by the above method. The copolymerizable monomer diol is not particularly limited. For example, ethylene glycol,
Linear diols such as 4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, propylene glycol,
Branched diols such as -methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, diethylene glycol, and trimethylolpropane, glycerin, pentaerythritol and any mixture thereof as a minor component. Is used.
Among them, 1,6-hexanediol, 1,9-nonanediol,
1,10-decanediol, 1,12-dodecanediol, 3-
The carbon chain length of methyl-1,5-pentanediol or the like is 5 to 12
Is frequently used. Furthermore, the coatability, adhesiveness, water resistance and durability of the adhesive from which 1,9-nondiol was obtained,
It is often used especially in terms of bending fatigue resistance and the like. When copolymerized, the content of 2-methyl-1,8-octanediol is not particularly limited, but is usually 10% or more, especially 25% or more. 1,9−
For nonanediol, the mixing ratio of 2-methyl-1,8-octanediol and 1,9-nonanediol is 5/95 to 9
The case of 0/10, and more preferably 70/30, is often used preferably from the viewpoints of the coating properties, adhesion, water resistance, durability and the like of the obtained adhesive. The dicarboxylic acid used for the condensation polymerization is not particularly limited, but, for example, succinic acid, glutaric acid,
Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, phthalic acid,
Aromatic dicarboxylic acids such as 5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid, or lower fatty acid esters thereof, and arbitrary mixtures thereof are used. Further, as a small component, aconitic acid, pyromellitic acid, trimellitic acid and the like can be used. Above all, dicarboxylic acid such as adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, or lower fatty acid esters thereof are obtained. Coating properties, adhesiveness, water resistance, durability, bending fatigue resistance, etc. In many cases, it is suitably used from the viewpoint of.

The method for producing the polyester polyol is not particularly limited, and a known polyester polymerization means can be applied. For example, a diol and a dicarboxylic acid monomer or a lower fatty acid ester thereof alone or in a mixed composition are charged in a desired composition and subjected to esterification and / or transesterification at 150 to 250 ° C. in the presence of an esterification and / or transesterification catalyst, The reaction intermediate thus obtained can be produced by further polymerizing it at 200 to 300 ° C. under high vacuum. Although the number average molecular weight is not particularly limited, it is usually 500 to 50,000, especially 900 to 20,000 in many cases.

When the polymer is a polyester polyurethane, the polyester polyol may have the same composition as the polyester polyol described above. Although there is no particular limitation on its molecular weight, it is usually a number average molecular weight of 500 to 5000
It is often used between 00 and 2000. The diisocyanate is not particularly limited, and includes known aliphatic, alicyclic, and aromatic diisocyanates containing two isocyanate groups in a molecule. Among them, 4,4'-diphenylmethane diisocyanate (MDI ), P-phenylene diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and the like, and 4,4'-diphenyl When methane diisocyanate, toluylene diisocyanate, isophorone diisocyanate or any mixture thereof is used, the obtained adhesive is suitably used from the viewpoints of coatability, adhesion, water resistance, durability, bending fatigue resistance and the like. Often used If necessary, it can be used by mixing with a polyfunctional polyisocyanate. As the polyfunctional polyisocyanate, a compound having three or more isocyanate groups in the molecule, for example, all of the hydroxyl groups such as trimethylolpropane, glycerin and pentaerythritol can be converted to urethane with toluylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc. Compounds which have been polyfunctionalized by condensation reaction of crude MDI, crude MDI, diisocyanate compound and water, and compounds which have been trimerized by thermal reaction of diisocyanate.

The production of polyester polyurethane is not particularly limited,
The method used for the usual urethane-forming reaction can be applied.
That is, if necessary, the polyester polyol and the diisocyanate can be added or reacted simultaneously or sequentially with the polyfunctional polyisocyanate mixture. For example, a polyester polyol having a number average molecular weight of 400 to 5,000 and, if necessary, a low molecular compound having two or more active hydrogens such as a hydroxyl group and an amino group are mixed or sequentially added, and an isocyanate group based on the number of active hydrogen atoms of these compounds is added. Ratio (NCO / OH)
Is obtained by reacting at a ratio of 1 or less. Examples of the low molecular weight compound having two or more active hydrogens such as a hydroxyl group and an amino group include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol,
Linear diols such as 10-decanediol and 1,12-dodecanediol, branched diols such as propylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol Is diethylene glycol or the like and any mixture thereof,
Examples include trimethylolpropane, glycerin, pentaerythritol and the like, as well as ethylenediamine, isophoronediamine, piperazine and hexamethylenediamine.
The above reaction may be carried out in the presence of an organic solvent inert to isocyanate groups. If desired, conventional urethanization catalysts may be used. As such, for example, amines such as triethylamine, triethylenediamine, morpholin, diazabicycloundecene and salts thereof, dibutyltin dilaurate, trimethyltin hydroxide, stannic chloride, potassium oleate, stannasoctoate, etc. Among them, there are metal salts. Among them, amines such as diazabicycloundecene and salts thereof, and dibutyltin dilaurate are often used well in terms of adhesiveness, workability, durability and the like. The compounding amount varies depending on the type of the catalyst used, the isocyanate compound, the composition of the polyester polyol, the required performance of the multilayer body, etc., but it is 0.5 to 5000 per adhesive solid, especially 1 to 500 ppm.
Often used in When the production process is performed in the presence of an organic solvent, the final solid content is often 10 to 90% by weight, and more often 15 to 70% by weight. There is no particular limitation on the viscosity of the polyurethane polyol obtained in this manner, but the concentration measured at 30 ° C. in terms of the manufacturing processability of the laminated structure, the adhesive strength of the obtained laminated structure, durability and the like. A viscosity of 30% by weight is often used at 10 to 40,000 centipoise (cps), especially 20 to 20,000 cps.

The polymer thus obtained can be used as an adhesive in the presence or absence of a solvent, but can be used as a mixture with a polyfunctional polyisocyanate. In that case, the polymer is often a polyester polyol or a polyurethane polyol having a hydroxyl group at a terminal.

Compounds having three or more isocyanate groups in the molecule as a polyfunctional polyisocyanate, for example, trimethylolpropane, glycerin, all hydroxyl groups such as pentaerythritol toluylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate,
Compounds which are urethanized with isophorone diisocyanate, crude MDI, compounds which are polyfunctionalized by condensation reaction of diisocyanate compound and water, and compounds which are trimerized by thermal reaction of diisocyanate, among which trimethylolpropane , Glycerin,
A compound in which all of the hydroxyl groups such as pentaerythritol are urethanized with toluylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate or the like is preferably used. The use of the above diisocyanate as a mixture with a compound having three or more isocyanate groups in the molecule may be used.

The compounding amount of the polyfunctional polyisocyanate is not particularly limited. Depending on the characteristic value of the polymer and the required performance of the adhesive, the compound can be used alone without compounding. In many cases, the heat treatment is favorable in terms of heat resistance and durability (bending fatigue resistance, water resistance, moisture and heat resistance, weather resistance). The compounding amount varies depending on the characteristic value of the polymer and the required performance of the adhesive, but it is often used in 1 to 30 parts by weight of 0.5 to 60 parts by weight per 100 parts by weight of the polymer.

The adhesive used in the present invention can be used as it is in the presence of a solvent if necessary, but applying a known compounding formulation used for a general polyurethane-based adhesive does not impair the object of the present invention. There is no problem in the range. Examples of such formulation include addition or grafting of a phosphorus compound, addition of an epoxy compound, addition of a silane coupling agent, an antioxidant, an ultraviolet absorber, a pigment, a dye, an inorganic filler, and the like. Although there is no particular limitation on the solvent, ethyl acetate, toluene, methyl ethyl ketone, DMF, methyl isobutyl ketone, acetone, tetrahydrofuran, halogenated hydrocarbons, or a mixture thereof is often used.

The thickness of the adhesive layer is related to the bending fatigue resistance of the multilayer body of the present invention, and the thickness of the flexible adhesive is large to prevent the propagation of the influence of the highly rigid EVOH. Contrary to what is expected to be more advantageous, the flex fatigue resistance tends to decrease with increasing layer thickness. In order to make the effects of the present invention more remarkable, the thickness of the layer is preferably 15 μm or less, more preferably 10 μm or less. Also, if the thickness of the adhesive is too thin, the technical difficulty of providing the layer with a uniform thickness without a break increases, so 0.5 μm or more, more preferably 1.0 μm
That is all.

The multilayer body of the present invention must not cause delamination at least during the bending fatigue test using the gel boflex tester.However, the adhesive of the present invention is used for EVOH and various polyolefin resins such as polyethylene and polypropylene. Has excellent adhesion to thermoplastic resins such as ethylene-vinyl acetate copolymer resin, polyamide resins such as various nylons, and various thermoplastic polyester resins, withstands extremely severe bending fatigue, and does not cause any delamination. In addition, the above-mentioned improvement effect is remarkably exhibited.

The EVOH resin used in the present invention has an ethylene content of 20 to 55.
Molar%, more preferably 25 to 50 mole%, and a saponification degree of 90% or more are suitably used. Ethylene content is 20 mol%
In the following, not only the moldability is reduced, but also it seems that this is related to the increase in the rigidity of the EVOH, but the effect of the present invention is diminished, and the rigidity decreases when the ethylene content exceeds 55 mol%. However, the most characteristic gas barrier property of the resin, such as oxygen, is lowered, which is unsatisfactory. The EVOH
The resin has an ethylene content in the range of 20-55 mol% 2
The effects of the present invention can be enjoyed as long as blends of the resins having different or different ethylene contents are within a range showing compatibility. The saponification degree of the resin is preferably 90% or more, and if it is less than 90%, the barrier property is undesirably reduced. ASTMD-1238 of this EVOH
The melt index (MI) measured at 190 ° C by
It is 0.1 to 25 g / 10 minutes, preferably 0.3 to 20 g / 10 minutes. In addition, EVOH treated with a boron compound such as boric acid, a third component such as a silicon-containing olefinically unsaturated monomer, α-olefin, N-vinylpyrrolidone are copolymerized with ethylene and vinyl acetate and saponified. The effect of the present invention can be enjoyed with modified EVOH as long as it has a degree of modification within a range that can be melt-molded and does not impair barrier properties.

The dependence of the EVOH layer thickness on the improvement effect in the construction of the laminated material of the present invention is extremely remarkable. If the thickness of the EVOH layer exceeds 40 μm, the effect of the improvement is undesirably diminished.
In order to fully enjoy the effects of the present invention, the thickness of the EVOH layer must be
40 μm or less is preferable, and 30 μm or less is more preferable. From the standpoint of the effect of the improvement alone, a size of 20 μm or less is particularly preferable. On the other hand, when there is a higher requirement for the gas barrier property of oxygen or the like, the requirement often cannot be satisfied with a thickness of the intermediate layer of 20 μm or less. An even more preferred embodiment of the present invention that satisfies higher requirements with respect to flex fatigue resistance and the barrier properties is that the thickness of the EVOH layer is less than 20%.
μ or less, preferably 15 μ or less, more preferably 10 μ or less, and two or more EVOH layers are provided in accordance with the degree of a high demand for the barrier property. However, when the EVOH layer is K and the adhesive resin layer is T, it means that it has a composite structure of K / T / K, K / T / K / T / K, etc. Includes

From the viewpoint of bending fatigue resistance, it is preferable that the thickness of the EVOH layer is as small as possible, but the difficulty from the viewpoint of the molding technique increases accordingly. Practically, 2 μm or more is preferable, and 5 μm or more is more preferable from this point of view with relatively little difficulty. Below 2μ, pinholes often occur
It occurs in the EVOH layer, and the yield of non-defective products decreases. In providing the plurality of barrier layers, the same EVOH of the ethylene-containing layer may be used for all of the layers, and when the relative humidity inside the container or the like is higher than the relative humidity outside the container, for example, When the packaged product is an aqueous mixture such as wine
In relation to the humidity dependence of the barrier property of EVOH, the positional relationship of each layer of the plurality of barrier layers is such that an EVOH layer having a smaller ethylene content is disposed outside and a larger ethylene content is provided.
It is more preferable to arrange the EVOH layer inside, and when the relationship of the relative humidity is reversed, it is preferable that the positional relationship of the EVOH layer is arranged reversely. Can be selected. In this case, it is preferable that at least two of the barrier layers are made of EVOH having a different ethylene content of 5 mol% or more in order to obtain the effect of the above configuration.

There is no particular limitation on the resin constituting the resin layer of the multilayer body. For example, polyolefin (polyethylene, polypropylene), polystyrene, ethylene-vinyl acetate copolymer or a saponified product thereof, vinyl chloride resin, saturated polyester resin (polyethylene terephthalate, polybutylene) Thermoplastic resins such as terephthalate), polyamide, polyurethane, and polycarbonate, and thermosetting resins such as phenolic resin, melamine resin, urea resin, and unsaturated polyester resin are used. Among them, polyolefin (polyethylene, polypropylene), vinyl chloride Resins, saturated polyester resins (polyethylene terephthalate, polybutylene terephthalate) and the like are preferably used. Further, polyamide is preferably used.

Further, it is desirable that at least one of the outermost layers of the multilayer body is a heat-sealable thermoplastic resin. As the heat sealable thermoplastic resin, linear low density polyethylene is the best. When this linear low-density polyethylene is used in at least one of the surface layers, particularly when both are used, the effect of the improvement by using the adhesive of the present invention is more remarkable. Here, the linear low-density polyethylene is a linear low-density polyethylene having substantially no long-chain branch. In general, a quantitative measure of the number of long chain branches, G =
[Η] b / [η] l ([η] b is the intrinsic viscosity of branched polyethylene, [η] l is the intrinsic viscosity of linear polyethylene having the same molecular weight as the branched polyethylene) is almost 1 (generally,
The density is 0.910 to 0.945 (the G value of a conventional ordinary high-pressure low-density polyethylene is 0.1 to 0.6). The method for producing the linear low-density polyethylene is not particularly limited.
For example, a typical production method has a pressure of 7 to 45 kg / cm ² (in the case of high-pressure low-density polyethylene, it is usually 2000 to 3000 kg / c).
m ² ) at a temperature of 75 to 100 ° C. (120 to 250 ° C. for high-pressure low-density polyethylene) using a chromium catalyst or a Ziegler catalyst to have 3 or more, preferably 4 or more, more preferably 5 to 5 carbon atoms. 10 alpha-olefins such as propylene, butene-1, methylpentene-1, hexene-1,
Α-olefin such as octene-1 as a copolymer component,
There is a method of copolymerizing ethylene. Although the copolymerization ratio varies depending on the kind of the α-olefin, it is often 7 mol% or less. As the polymerization method, a solution method liquid phase method, a slurry method liquid phase method, a fluidized bed gas phase method, a stirred bed gas phase method and the like are used.

As described above, the effects of the present invention, the carbon number of the α-olefin and the heat of fusion of the linear low-density polyethylene by thermal analysis with a differential scanning calorimeter are further closely related to the Young's modulus as described above. More specifically, it is as follows. Although linear low-density polyethylene is suitably used in the present invention, the heat of fusion is 25 cal / g or less, preferably 25 to 5 ca.
l / g or a Young's modulus at 20 ° C of 22 kg / mm ²
Hereinafter, preferably 22 to 3 kg / mm ² , more preferably 22 to 5
The effect of the present invention is more remarkable for the polyethylene having a weight of kg / mm ² , especially when both are in the above-mentioned region. Those having the heat of fusion and Young's modulus in the above range slightly vary depending on the polymerization method and polymerization conditions, but generally speaking, the content of the α-olefin as a copolymer component is about 2 mol% or more, preferably It is often obtained in the range of about 2 to 7 mol%. For the linear low-density polyethylene whose copolymer component is butene-1, when the heat of fusion is 15 cal / g or more, or the Young's modulus at 20 ° C. is 12 kg / mm ² or less, the effect of the present invention is The effect is more remarkable, and the effect can be most remarkably enjoyed particularly when both are in the region. The low-density polyethylene having the heat of fusion and Young's modulus in the above-mentioned range is generally obtained in a range where the content of butene-1 is about 4 mol% or more. If the content is too high, the other physical properties of the polyethylene become unsatisfactory, which is not preferable. The content is desirably at most several mol%, for example, 7 mol%.
The effect of the present invention can be enjoyed with the linear low-density polyethylene having the heat of fusion and / or the Young's modulus in the specific region as described above. Particularly, α-olefin having 5 or more carbon atoms, for example, 5 to 10 carbon atoms. The effect can be more remarkably enjoyed for the polyethylene containing as a copolymer component. In this case, for the same reason as described above, the content of the α-olefin is 2 to 7 mol%, more specifically, 2 to 6 mol%.
Preferably, the heat of fusion is related to the α-olefin content and the like as described above, and particularly, the heat of fusion is 25 to 5 c
is preferably al / g, also Young's modulus is 22 kg / mm ² or less, preferably 22~3kg / mm ^2, more preferably 22~5kg
a / mm ^2. Among the olefins, the effects of the present invention are more remarkable, and 4-methyl-1 which can be easily obtained industrially
-A linear low-density polyethylene having pentene as a copolymer component is one of the most preferred ones.

Another heat sealable thermoplastic resin used for the surface layer of the present invention is an ethylene-vinyl acetate copolymer. In particular, the copolymer having a vinyl acetate content of at least 7% by weight can more remarkably enjoy the effects of the present invention. If the content is too large, the resin surface becomes sticky, which is not preferable, and is preferably 12% by weight or less. When the packing material such as a packaging container comprising the laminated material of the present invention is an aqueous mixture or a water-containing food, the copolymer is used as an outer surface layer in relation to the moisture permeability of both the inner and outer surface layers, and the linear An embodiment in which the low-density polyethylene is used as the inner surface layer is one of the preferable constitutions of the laminated packaging material because the EVOH layer disposed as the intermediate layer can keep the steady moisture at a lower level. Further, in the case of the packing filling, when further excellent bending fatigue resistance is required, the copolymer having a higher moisture permeability than the polyethylene is applied to the inner and outer surface layers within a limit satisfying the requirement of the barrier property. The thickness of the inner and outer surface layers to be used is selected so as to satisfy the condition for the moisture permeability, and the structure is such that the steady-state moisture of the EVOH layer is maintained in a suitable region, so that it can be suitably used. Other heat-sealable thermoplastic resins (at least on one side) include high-pressure low-density polyethylene, low-pressure high-density polyethylene, polyolefin resins such as polypropylene, polyamide resins such as various nylons, and polyester resins. Examples of the resin which is difficult to heat seal for use in the surface layer include stretched resins such as biaxially stretched polypropylene and nylon.

Although the melt viscosity of the resin used for the surface layer can be appropriately selected, the MI of the surface layer measured at 19 ° C. according to ASTM-D-1238 is 0.1 to 20 g / 10 min, preferably 0.2 to 10 g / 10 min.

These resins may be formed in advance into a film shape, a cylindrical shape, or the like, but in this case, they may be stretched uniaxially or biaxially or may not be stretched. Further, secondary processing such as corona processing and plasma processing may be performed. The thickness of the resin layer is not particularly limited, but is usually 10 μm to 2 mm, and more often 15 μm to 200 μm.

In bonding, the adherends formed in advance can be joined to each other by a method such as wet lamination, dry lamination, or hot melt lamination using the above-mentioned adhesive to form a multilayer structure. Further, a method such as a so-called calendering method or an extruder laminating method for extruding a thermoplastic resin such as polyvinyl chloride on a metal foil layer to which the above-mentioned adhesive has been applied in advance can be applied.

Assuming that the layer of the saponified ethylene-vinyl acetate copolymer used in the present invention is (A), the layer of the resin is (B), and the adhesive layer used in the present invention is (C), the present invention will be described. The resulting multilayer body is represented by (A) / (C) / (B). However,
When (A) or (B) is the same type or another type of layer as (D), and (C) is the same type or another type of adhesive layer as (E), for example, (D) / (E) ) / (A) / (C) / B), (D) / (E) / (A) / (C) / (B) / (E) /
(D), (A) / (C) / (B) / (E) / (D), or the (D) layer may have a multilayer structure. Examples of the material forming such a layer include polyolefin (polyethylene, polypropylene), polystyrene, ethylene-vinyl acetate copolymer or a saponified product thereof, plasticized or hard vinyl chloride, polyester (polyethylene terephthalate, polybutylene terephthalate), Polyamide, thermoplastic resin such as polyurethane, phenol resin, melamine resin, thermosetting resin such as urea resin, natural rubber, polyisoprene, ethylene propylene diene terpolymer, synthetic rubber such as styrene-butadiene, aluminum, copper, iron, Examples include metals such as stainless steel, fiber structures such as woven fabric, knitted fabric, and nonwoven fabric, wood, and glass.

The gas-barrier multilayer body obtained in this way has extremely excellent normal adhesion, low temperature resistance, and durability (water resistance, heat resistance, content resistance, flex fatigue resistance, etc.). It is extremely useful in practical applications, such as the interior of bag-in-boxes, the food packaging field requiring retort food and boil sterilization, the coating of underground power cables, wrap tape, electromagnetic wave shielding plates, flexible prints, and automobile moldings.

(Example) Example 1 60 mol% of 2-methyl-1,8-octanediol and 40 mol% of 1,9-nonanediol are contained as diol components, adipic acid is 50 mol% as a dicarboxylic acid component, and isophthalic acid is contained. Contains 50 mol% of acid and has a number average molecular weight of 1800
1800 parts by weight of polyester diol (DO-1), 42 parts by weight of trimethylpropane, 252 parts by weight of isophorone diisocyanate and 2 parts of ethyl acetate dried as a solvent.
088 parts by weight are charged and dissolved in a reactor under a stream of nitrogen.
0.04 parts by weight of iron acetylacetonate was added as a catalyst, and the reaction was completed under reflux of the solvent. A predetermined amount of ethyl acetate was added and diluted to a solid concentration of 30% (A-1).
The viscosity was measured at a temperature of 30 ° C. and found to be 50 centipoise. Takenate A-50 was used as a polyfunctional polyisocyanate (curing agent) with respect to 100 parts by weight of the polymer solution A-1.
7.5 parts by weight (trademark: Takeda Pharmaceutical) were blended to prepare an adhesive solution (AB-1).

The above adhesive solution (A) was added to a corona-treated unstretched linear low-density polyethylene film having a thickness of 40 µm (LLDPE: containing 3.2 mol% of 4-methyl-1-pentene as a copolymer component).
B-1) was applied as a solid to 3.5 g / m ^2, and the solvent was volatilized with hot air at 45 ° C., and then a laminator was used. , Saponification degree
A 99.5% unstretched ethylene-vinyl acetate saponified layer is bonded, and then an adhesive solution (AB-1) is applied to a 12 μm thick polyethylene terephthalate in the same manner so that the solid content becomes 3.5 g / m ^2. Combine and continue curing at 40 ° C. After 20 days, test specimens are cut out and gelbo flex tester GELB
Using an O Flex Tester (specified in US Military Standard MIL-B-131 “Flexible Moisture-Proof Barrier Material”), a bending fatigue resistance test was performed as follows. The bending fatigue resistance was evaluated based on the number of bendings before the occurrence of pinholes. The occurrence of pinholes was observed at the number of flexing of 240 times, indicating good performance.

Comparative Example 1 Instead of DO-1, 60 mol% of 1,6-hexanediol and 40 mol% of neopentyl glycol were used as diol components.
Example 1 except that a polyester diol containing 50 mol% of adipic acid and 50 mol% of isophthalic acid as a dicarboxylic acid component and having a number average molecular weight of 1800 was used.
A laminate film was prepared in the same manner as described above, and then the performance was evaluated in the same manner. The occurrence of pinholes was observed at the number of bending of 110 times, the bending fatigue resistance was insufficient, and the effect of the present invention is clear.

Example 2 Using the adhesive solution (AB-1) obtained in Example 1 above, an ethylene content of 32 μm in a thickness of 15 μm and a saponification degree of 99.5 were used.
% Biaxially stretched ethylene-vinyl acetate saponified layer and thickness 20%
μ unstretched polypropylene layer and 4.1 g / m in adhesive solids
After coating the ² become as bonding, KoTsuta the evaluation of bending fatigue resistance in the same manner as in Example 1. Pinholes were observed at the number of flexing of 250 times, showing good performance.

Comparative Example 2 Instead of DO-1, the diol component contained 50 mol% of ethylene glycol and 50 mol% of diethylene glycol, the dicarboxylic acid component contained 50 mol% of adipic acid, 50 mol% of isophthalic acid, and a number average Molecular weight 1800
An adhesive was obtained in the same manner as in Example 1 except that the polyester diol was used. Next, a laminate film was prepared in the same manner as in Example 2, and then the performance was evaluated in the same manner. The occurrence of pinholes was observed at the number of bending of 130 times,
The bending fatigue resistance is insufficient, and the effect of the present invention is clear.

Example 3 50 mol% of 2-methyl-1,8-octanediol and 50 mol% of 1,9-nonanediol were contained as diol components, and 50 mol% of sebacic acid and 50 mol of isophthalic acid were contained as dicarboxylic acid components. % And a number average molecular weight of 1200
Of polyester diol (DO-2), 189 parts by weight of isophorone diisocyanate and 1389 parts by weight of dry ethyl acetate as a solvent are introduced into a reactor under a stream of nitrogen gas and dissolved. 0.03 parts by weight of iron acetylacetonate is added as a catalyst, and the reaction is completed under reflux of the solvent. Then, a predetermined amount of ethyl acetate was added, and the solid content concentration was 30.
% (A-2), and the viscosity was measured at a temperature of 30 ° C. and found to be 62 centipoise.

10 parts by weight of Takenate A-50 was mixed as a curing agent with 1200 parts by weight of the main agent (A-2) to prepare an adhesive solution (AB-2).

Using the solution, the adhesive solution (AB-2) was added to a corona-treated 25 μm-thick unstretched ethylene-vinyl acetate copolymer film (EVA: containing 8 mol% of vinyl acetate as a copolymer component). Apply at a solid content of 3.2 g / m ² at 45 ° C
After evaporating the solvent with warm air, a laminator was used to bond an unstretched ethylene-vinyl acetate saponified layer having a thickness of 15 μm and an ethylene content of 45 mol% and a saponification degree of 99.5% at a roll temperature of 65 ° C. In the same way as for 12μ nylon, glue is applied after applying so that the adhesive becomes 3.5 g / m ² in solid content,
The bending fatigue resistance was evaluated in the same manner as in Example 1. Pinholes were observed at 350 flexes, indicating good performance.

Comparative Example 3 A multilayer body was obtained in the same manner as in Example 3 except that the adhesive obtained in Comparative Example 2 was used instead of the adhesive solution (AB-2). Subsequently, performance evaluation was performed in the same manner as in Example 3. Pinholes were generated at the number of bending of 150 times, the bending fatigue resistance was insufficient, and the effect of the present invention is clear.

Claims (9)

(57) [Claims] 1. A multilayer body comprising a layer of a saponified ethylene-vinyl acetate copolymer having an ethylene component content of 20 to 55 mol% and a degree of saponification of 90% or more and a resin layer, the following intermediate layer (I): A gas-barrier multilayer body comprising an adhesive mainly composed of a polymer containing a structural unit represented by the formula. —OCH ₂ CH (CH ₃ ) (CH ₂ ) ₆ O− (I) 2. The method according to claim 1, wherein the resin is a polyolefin.
The gas-barrier multilayer body according to item 1. 3. The gas-barrier multilayer body according to claim 1, wherein the polymer is a polyester polyurethane polyol. 4. The gas-barrier multilayer body according to claim 3, wherein the intermediate layer comprises a polymer which is a polyester polyurethane polyol and a polyfunctional polyisocyanate. 5. A gas-blocking multilayer body according to claim 1, wherein the resin layer of the gas-blocking multilayer body is made of a heat-sealable thermoplastic resin. A gas-blocking multilayer body further comprising a heat-sealable thermoplastic resin layer on at least one of the surfaces of the multilayer body. 6. The gas barrier multilayer according to claim 5, wherein the heat-sealable thermoplastic resin is an ethylene-vinyl acetate copolymer containing a vinyl acetate component in an amount of 7% by weight or more. 7. A multilayer packaging material in which a filler is packaged in a multilayer packaging material comprising the gas barrier multilayer according to any one of claims (1) to (6). 8. The multilayer packaging material according to claim 7, wherein the packaging filling of the multilayer packaging material is an aqueous mixture or a water-containing material, and the multilayer packaging material comprising the multilayer body is in the form of a packaging container. 9. The packaging material according to claim 8, wherein said packaging material is a component of a bag-in-box inner container.