JP2012250577A - Multilayer structure, inner liner for pneumatic tire, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light weighted multilayer structure which has gas barrier property and the crack resistance property, and to provide an inner liner for a pneumatic tire, which uses the multilayer structure, and the pneumatic tire equipped with the inner liner.SOLUTION: In the multilayer structure 1 with seven or more layers alternately stacked in total including a resin composition layer 2 of a thickness of 0.001 to 10 μm, and an elastomer layer 3 of a thickness of 0.001 to 10 μm, at least one layer 2' in the resin composition layers 2 includes a filler 4.

Description

  The present invention relates to a multilayer structure, a pneumatic tire inner liner using the multilayer structure, and a pneumatic tire including the inner liner, and in particular, a multilayer that can achieve both gas barrier properties and crack resistance and is reduced in weight. It relates to a structure.

  Conventionally, a rubber composition mainly composed of butyl rubber, halogenated butyl rubber or the like is used for an inner liner disposed as an air resin composition layer on the inner surface of the tire in order to maintain the internal pressure of the tire. However, these rubber compositions containing butyl rubber as the main raw material have low air barrier properties, and therefore when the rubber composition is used for an inner liner, the thickness of the inner liner has to be about 1 mm. In that case, the mass ratio of the inner liner to the tire is about 5%, which is an obstacle in terms of improving the fuel efficiency of the automobile.

  On the other hand, resins including ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) are known to have excellent gas barrier properties. Since the EVOH has an air permeability of 1/100 or less of the above butyl rubber composition for an inner liner, even if the thickness is 100 μm or less, the internal pressure retention of the tire can be greatly improved. Therefore, when EVOH is used as an inner liner, it can be used even with a thickness of 100 μm or less, and therefore, it is difficult to break due to bending deformation at the time of tire rolling, and cracks are also difficult to occur. Therefore, it can be said that it is effective to use EVOH for the inner liner of the tire in order to improve the internal pressure retention of the pneumatic tire. For example, Patent Literature 1 discloses a pneumatic tire including an inner liner made of EVOH.

  However, when normal EVOH is used as an inner liner, the effect of improving the internal pressure retention of the tire is great, but normal EVOH has a significantly higher elastic modulus than rubber normally used for tires, so when bent, Breaking or cracking may occur due to deformation. Therefore, when the inner liner made of EVOH is used, the internal pressure retention before using the tire is greatly improved, but the internal pressure retention is lower than that before using the tire after being subjected to bending deformation during rolling of the tire. There was something to do.

JP-A-6-40207

  Then, the objective of this invention is providing the multilayer structure by which weight reduction was achieved, having excellent gas-barrier property and crack resistance by optimizing the resin composition layer. Another object of the present invention is to provide an inner liner for a pneumatic tire using such a multilayer structure and a pneumatic tire including the inner liner.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have a resin composition layer containing a gas barrier resin and an average thickness of 0.001 to 10 μm, and an elastomer composition containing an elastomer material. It is possible to realize a high gas barrier property while reducing the weight of the multilayer structure by alternately laminating a total of 7 or more layers of elastomer layers having an average thickness of 0.001 to 40 μm. Furthermore, it has been found that high crack resistance can be realized by including a filler in at least one of the resin composition layers, and the present invention has been completed.

  That is, the multilayer structure of the present invention is a multilayer structure in which a resin composition layer and an elastomer layer are alternately laminated in total seven or more layers, and the resin composition layer has an average thickness of one layer. The elastomer layer has an average thickness of 0.001 to 40 μm, and at least one of the resin composition layers includes a filler.

The filler is preferably an inorganic filler, and the inorganic filler is more preferably a layered or plate-like compound or carbon black.
The layered or plate-like compound is more preferably a composite of hydrous silica and alumina.

In a preferred example of the multilayer structure of the present invention, the oxygen permeation coefficient at 20 ° C. and 65 RH% of the elastomer contained in the elastomer layer is 3.0 × 10 ^{−11 to} 3.0 × 10 ⁻⁹ cm ³ · cm ² / cm ² · The oxygen permeability coefficient at 20 ° C. and 65 RH% of the barrier resin contained in the resin composition layer is 8.0 × 10 ⁻¹² cm ³ · cm ² · sec · cmHg or less.

  An inner liner for a pneumatic tire according to the present invention is characterized by using the multilayer structure described above, and further, the pneumatic tire according to the present invention is provided with the inner liner.

  According to the present invention, it is possible to provide a multilayer structure having a light weight while having excellent gas barrier properties and crack resistance. Moreover, an inner liner for a pneumatic tire using such a multilayer structure and a pneumatic tire including the inner liner can be provided.

It is sectional drawing of an example of the multilayer structure of this invention. It is a fragmentary sectional view of an example of the pneumatic tire of the present invention. It is sectional drawing which expanded and showed a part of resin composition layer which comprises the multilayer structure of this invention.

(Multilayer structure)
Hereinafter, the multilayer structure of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an example of the multilayer structure of the present invention.
The multilayer structure 1 of the present invention, as shown in FIG. 1, requires that the resin composition layer 2 and the elastomer layer 3 are alternately laminated in a total of 7 or more layers,
The resin composition layer 2 has a single layer average thickness of 0.001 to 10 μm, the elastomer layer 3 has a single layer average thickness of 0.001 to 40 μm, and at least one layer 2 ′ of the resin composition layer 2 ′. Is characterized by containing a filler

  By stacking the resin composition layers 2 alternately in total of 7 or more layers, the high gas barrier property of the multilayer structure 1 can be realized. Moreover, although the air permeation suppression force is high, since the elastic modulus is high and the flexibility is poor, the thickness of the resin composition layer 2 that has conventionally been the origin of cracks is as thin as 0.001 to 10 μm. By doing so, the effect of toughening can be obtained, and the resin composition layer 2 'of at least one layer contains the filler 4, so that the substantial thickness of the resin in the resin composition layer 2' can be reduced. Since it becomes thinner (apparently thinner), the effect of further toughening can be obtained, and the crack resistance of the multilayer structure 1 can be improved. Moreover, when an inorganic filler is added, the air permeation suppression force can be further improved.

  The total number of layers of the barrier resin composition layer 2 is not particularly limited as long as it is 7 layers or more, but is preferably 11 layers or more and more preferably 15 layers or more from the viewpoint of realizing higher gas barrier properties. More preferably it is.

  For example, polystyrene is mentioned as an example of a material used for a conventional resin composition layer. Polystyrene is known as a brittle material, and the layer made of polystyrene is broken by about 1.5% elongation at room temperature. There is a risk that. However, in “Polymer, 1993, vol. 34 (10), 2148-2154”, a layer made of a ductile material and a layer made of polystyrene are laminated, and the thickness of each layer made of polystyrene is 1 μm or less. Thus, it has been reported that a layer made of polystyrene is modified from brittle to ductile. That is, it is considered that even a layer made of a brittle material such as polystyrene can be modified to toughness by making the layer very thin. The present inventors have paid attention to such a concept and have found a multilayer structure capable of achieving both excellent gas barrier properties and crack resistance.

  In the multilayer structure of the present invention, as shown in FIG. 1, the thicknesses U1, U2, U3... Un of the elastomer layer 3 are all in the range of 0.001 to 40 μm. Further, the thicknesses V1, V2, V3... Vn of the resin composition layer 2 are all in the range of 0.001 to 10 μm. By making the thicknesses U and V of the respective layers 3 and 4 within the above ranges, the crack resistance can be improved by toughening, and the number of layers constituting the multilayer structure can be increased. Can improve the gas barrier property and crack resistance of the multilayer structure as compared with the multilayer structure having the same number of layers but a small number of layers.

  Moreover, as shown in FIG. 1, the thickness T of the multilayer structure 1 of the present invention is preferably in the range of 0.1 to 1000 μm, more preferably in the range of 0.5 to 750 μm, and still more preferably in the range of 1 to 500 μm. If the thickness of the multilayer structure is within the above range, it is suitable as an inner liner for a pneumatic tire, and coupled with limiting the average thickness of one layer of the resin composition layer and the elastomer layer, Cracking properties and the like can be further improved.

  Moreover, it is preferable that the multilayer structure 1 of this invention is bridge | crosslinked by irradiation of an active energy ray. By cross-linking the multilayer structure 1 by irradiation with active energy rays, the affinity between the stacked layers 2 and 3 can be improved and high adhesiveness can be expressed. As a result, the interlayer adhesion of the multi-layer structure 1 body, and thus the gas barrier property and crack resistance can be remarkably improved. The active energy rays mean those having energy quanta among electromagnetic waves or charged particle beams, and specific examples include ultraviolet rays, γ rays, electron beams, etc. Among these, improvement of interlayer adhesion From the viewpoint of effects, an electron beam is preferable. When irradiating an electron beam as an active energy ray, the electron beam source is, for example, a Cockroft Walton type, a bandegraft type, a resonant transformer type, an insulated core transformer type, or a linear type, a dynamitron type, a high frequency type, etc. Various electron beam accelerators can be used, the acceleration voltage is usually 100 to 500 kV, and the irradiation dose is usually in the range of 5 to 600 kGy. Moreover, when using an ultraviolet-ray as an active energy ray, what contains the ultraviolet-ray with a wavelength of 190-380 nm is good to irradiate. There is no restriction | limiting in particular as an ultraviolet-ray source, For example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a carbon arc lamp etc. are used.

(Resin composition layer)
The resin composition layer constituting the multilayer structure of the present invention is a layer for imparting gas barrier properties to the multilayer structure, and is a layer composed of a resin or a layer composed of a resin composition in which the resin exists as a matrix. . The matrix means a continuous phase.

The oxygen permeability of the resin composition layer at 20 ° C. and 65% RH is preferably 8.0 × 10 ⁻¹² cm ³ / cm ² · sec · cmHg or less, and 1.0 × 10 ⁻¹² cm ³ / cm ² More preferably, it is not more than sec · cmHg, more preferably not more than 5.0 × 10 ⁻¹³ cm ³ / cm ² · sec · cmHg. When the oxygen permeability at 20 ° C. and 65% RH exceeds 8.0 × 10 ⁻¹² cm ³ / cm ² · sec · cmHg, the resin composition layer must be thickened to increase the internal pressure retention of the tire. Therefore, the weight of the inner liner cannot be sufficiently reduced.

O Gas barrier resin Since the resin composition layer is a layer for imparting gas barrier properties to the multilayer structure as described above, it contains a gas barrier resin. Here, the gas barrier resin is a resin that exhibits a certain gas barrier effect by being contained in the layer.

  The gas barrier resin is not particularly limited as long as the resin composition layer to be formed has a good air permeation suppressing force and an appropriate mechanical strength. -Vinyl alcohol copolymer resin (EVOH), modified ethylene-vinyl alcohol copolymer resin (modified EVOH), polyamide resin (PA), polyvinyl alcohol resin (PVA), polyvinylidene chloride resin (PVDC), polyethylene terephthalate (PET) And polyacrylonitrile. Among these, polyvinyl alcohol resin, polyamide resin, ethylene-vinyl alcohol copolymer resin and modified ethylene-vinyl alcohol copolymer resin are preferable. Since these resins have a low elastic modulus, the elastic modulus of the resin composition layer can be reduced and a toughness effect can be obtained. As a result, durability such as crack resistance can be improved. In addition, about the said resin, it may be used individually by 1 type and may be used in combination of 2 or more type.

  The polyamide resin (PA) is a general term for polymer compounds having an amide bond formed by a reaction between an acid and an amine, and has good mechanical properties and is resistant to tension, compression, bending, and impact.

  Specific examples of the polyamide resin include aliphatic polyamide homopolymers such as nylon 6, nylon-11, nylon-12, nylon-6,6, nylon 6-10, and the like; nylon-6 / 12, nylon 6/6, Aliphatic polyamide copolymers such as 6; polymetaxylene adipamide (MX nylon), nylon MXD6, aromatic polyamide and the like. Among these, nylon-6 and nylon 6,6 are public.

  The vinylidene chloride resin may be polyvinylidene chloride, but usually a vinylidene chloride copolymer can be used publicly. A vinylidene chloride copolymer is a copolymer of vinylidene chloride and a copolymerizable monomer. Examples of such copolymeric monomers include vinyl halide (vinyl chloride), carboxylic acid vinyl ester ( Examples thereof include vinyl acetate) and (meth) acrylic acid esters (for example, methyl (meth) acrylate, butyl (meth) acrylate, etc.).

  Examples of the polyester resins include aliphatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, directional polyesters such as polybutylene naphthalate, and copolymer polyesters such as polybutylene terephthalate / polytetramethylene glycol copolymer. Etc. are exemplified.

  The ethylene-vinyl alcohol copolymer resin preferably has an ethylene content of 3 to 70 mol%, from 10 to 60 mol, from the viewpoint of improving gas barrier properties, melt moldability and interlayer adhesion of the multilayer structure. % Is more preferable, 20 to 55 mol% is more preferable, and 25 to 50 mol% is particularly preferable. If the ethylene content exceeds 70 mol%, the gas barrier properties of the multilayer structure may be reduced.

  The ethylene-vinyl alcohol copolymer resin preferably has a saponification degree of 80% or more, more preferably 90% or more from the viewpoint of improving gas barrier properties, moisture resistance and interlayer adhesion of the multilayer structure. Preferably, it is more preferably 95% or more, and particularly preferably 99% or more. On the other hand, the saponification degree of the ethylene-vinyl alcohol copolymer resin is preferably 99.99% or less. If the saponification degree of EVOH is less than 80%, the melt moldability, gas barrier properties, coloration resistance and moisture resistance of the multilayer structure may be lowered.

  The ethylene-vinyl alcohol copolymer resin has a melt flow rate (MFR) of 0.1 to 30 g / 10 min at 190 ° C. and a load of 21.18 N from the viewpoint of obtaining gas barrier properties, flex resistance and fatigue resistance. Preferably, it is 0.3-25 g / 10min.

The ethylene-vinyl alcohol copolymer resin has a content G (mol%) of 1,2-glycol bond structural units of the following formula:
G ≦ 1.58−0.0244 × E
[Wherein, G is the content (mol%) of 1,2-glycol bond structural unit, E is the ethylene unit content (mol%) in EVOH, where E ≦ 64) And the intrinsic viscosity is preferably in the range of 0.05 to 0.2 L / g. By using such EVOH, the resulting multilayer structure is less dependent on the humidity of the gas barrier property, has good transparency and gloss, and can be easily laminated on a layer made of another resin. The content of the 1,2-glycol-bonded structural unit was determined by changing the EVOH sample to a dimethyl sulfoxide solution according to the method described in “S. Aniya et al., Analytical Science Vol. 1, 91 (1985)”. It can be measured by nuclear magnetic resonance at 90 ° C.

  The modified ethylene-vinyl alcohol copolymer resin has one or more kinds of other repeating units (hereinafter also referred to as structural units), for example, repeating units derived from these units, in addition to ethylene units and vinyl alcohol units. It is a polymer. The preferred ethylene content, degree of saponification, melt flow rate (MFR), content of 1,2-glycol bond structural unit and intrinsic viscosity of the modified EVOH are the same as those of the above-mentioned EVOH.

上記式（Ｉ）中、Ｒ^１、Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、炭素数１〜１０の脂肪族炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１０の芳香族炭化水素基又は水酸基を表す。また、Ｒ^１、Ｒ^２及びＲ^３のうちの一対が結合していてもよい（但し、Ｒ^１、Ｒ^２及びＲ^３のうちの一対が共に水素原子の場合は除く）。また、前記炭素数１〜１０の脂肪族炭化水素基、炭素数３〜１０の脂環式炭化水素基又は炭素数６〜１０の芳香族炭化水素基は、水酸基、カルボキシ基又はハロゲン原子を有していてもよい。一方、上記式（ＩＩ）中、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^７は、それぞれ独立して、水素原子、炭素数１〜１０の脂肪族炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１０の芳香族炭化水素基又は水酸基を表す。また、Ｒ^４とＲ^５又はＲ^６とＲ^７は結合していてもよい（但し、Ｒ^４とＲ^５又はＲ^６とＲ^７が共に水素原子の場合は除く）。また、前記炭素数１〜１０の脂肪族炭化水素基、炭素数３〜１０の脂環式炭化水素基又は炭素数６〜１０の芳香族炭化水素基は、水酸基、アルコキシ基、カルボキシ基又はハロゲン原子を有していてもよい。 The modified EVOH preferably has, for example, at least one structural unit selected from the structural units (I) and (II) shown below, and the structural unit is 0.5 to 30 mol% based on the total structural units. More preferably, it is contained in a proportion. Such a modified EVOH can improve the flexibility and processing characteristics of the resin or resin composition, and the interlayer adhesion, stretchability, and thermoformability of the multilayer structure.

In the above formula (I), R ¹ , R ² and R ³ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, An aromatic hydrocarbon group or a hydroxyl group having 6 to 10 carbon atoms is represented. In addition, a pair of R ¹ , R ² and R ³ may be bonded (except when a pair of R ¹ , R ² and R ³ are both hydrogen atoms). In addition, the aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms, or the aromatic hydrocarbon group having 6 to 10 carbon atoms has a hydroxyl group, a carboxy group, or a halogen atom. You may do it. On the other hand, in said formula (II), R < ⁴ >, R < ⁵ >, R < ⁶ > and R <^7> are respectively independently a hydrogen atom, a C1-C10 aliphatic hydrocarbon group, and a C3-C10 alicyclic ring. A formula hydrocarbon group, a C6-C10 aromatic hydrocarbon group, or a hydroxyl group is represented. R ⁴ and R ⁵ or R ⁶ and R ⁷ may be bonded to each other (except when R ⁴ and R ⁵ or R ⁶ and R ⁷ are both hydrogen atoms). In addition, the aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms, or the aromatic hydrocarbon group having 6 to 10 carbon atoms is a hydroxyl group, an alkoxy group, a carboxy group, or a halogen atom. You may have an atom.

  In the modified EVOH, the lower limit of the content of the structural unit (I) and / or (II) with respect to all the structural units is preferably 0.5 mol%, more preferably 1 mol%, and further preferably 1.5 mol%. preferable. On the other hand, in the modified EVOH, the upper limit of the content of the structural unit (I) and / or (II) with respect to all the structural units is preferably 30 mol%, more preferably 15 mol%, still more preferably 10 mol%. By containing the structural units (I) and / or (II) in the specified ratio, flexibility and processing characteristics of the resin or resin composition, interlayer adhesion, stretchability, and thermoformability of the multilayer structure Can be improved.

  In the structural units (I) and (II), examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include an alkyl group and an alkenyl group, and examples of the alicyclic hydrocarbon group having 3 to 10 carbon atoms include cyclohexane. An alkyl group, a cycloalkenyl group, etc. are mentioned, A phenyl group etc. are mentioned as a C6-C10 aromatic hydrocarbon group.

In the structural unit (I), R ¹ , R ² and R ³ are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a hydroxyl group, a hydroxymethyl group or a hydroxyethyl group. More preferably, they are each independently a hydrogen atom, a methyl group, a hydroxyl group or a hydroxymethyl group. With such R ¹ , R ² and R ³ , the stretchability and thermoformability of the multilayer structure can be further improved.

  The method for incorporating the structural unit (I) in EVOH is not particularly limited. For example, in the copolymerization of ethylene and vinyl ester, a monomer further derived into the structural unit (I). And the like. Examples of the monomer derived from the structural unit (I) include alkene such as propylene, butylene, pentene, hexene; 3-hydroxy-1-propene, 3-acyloxy-1-propene, 3-acyloxy-1 -Butene, 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-hydroxy-1-butene, 4-acyloxy-3-hydroxy-1-butene, 3-acyloxy-4 -Methyl-1-butene, 4-acyloxy-2-methyl-1-butene, 4-acyloxy-3-methyl-1-butene, 3,4-diacyloxy-2-methyl-1-butene, 4-hydroxy-1 -Pentene, 5-hydroxy-1-pentene, 4,5-dihydroxy-1-pentene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, , 5-diacyloxy-1-pentene, 4-hydroxy-3-methyl-1-pentene, 5-hydroxy-3-methyl-1-pentene, 4,5-dihydroxy-3-methyl-1-pentene, 5,6 -Dihydroxy-1-hexene, 4-hydroxy-1-hexene, 5-hydroxy-1-hexene, 6-hydroxy-1-hexene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy Alkenes having a hydroxyl group or an ester group such as -1-hexene and 5,6-diacyloxy-1-hexene are exemplified. Among these, from the viewpoint of copolymerization reactivity and gas barrier properties of the resulting multilayer structure, propylene, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, and 3 1,4-diacetoxy-1-butene is preferred. Specifically, propylene, 3-acetoxy-1-propene, 3-acetoxy-1-butene, 4-acetoxy-1-butene, and 3,4-diacetoxy-1-butene are more preferable, and 3,4-diacetoxy- 1-butene is particularly preferred. In addition, when using the alkene which has ester, it is induced | guided | derived to the said structural unit (I) in the case of saponification reaction.

In the structural unit (II), R ⁴ and R ⁵ are preferably both hydrogen atoms. In particular, it is more preferable that R ⁴ and R ⁵ are both hydrogen atoms, one of the R ⁶ and R ⁷ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and the other is a hydrogen atom. The aliphatic hydrocarbon group in the structural unit (II) is preferably an alkyl group or an alkenyl group. Further, from the viewpoint of particularly emphasizing the gas barrier property of the multilayer structure, it is preferable that one of R ⁶ and R ⁷ is a methyl group or an ethyl group, and the other is a hydrogen atom. Furthermore, it is also preferable that one of R ⁶ and R ⁷ is a substituent represented by (CH ₂ ) _h OH (where h is an integer of 1 to 8) and the other is a hydrogen atom. In the substituent represented by (CH ₂ ) _h OH, h is preferably an integer of 1 to 4, more preferably 1 or 2, and particularly preferably 1.

上記式（ＩＩＩ）〜（ＩＸ）中、Ｒ^８、Ｒ^９、Ｒ^１０、Ｒ^１１及びＲ^１２は、水素原子、炭素数１〜１０の脂肪族炭化水素基（アルキル基又はアルケニル基等）、炭素数３〜１０の脂環式炭化水素基（シクロアルキル基又はシクロアルケニル基等）又は炭素数６〜１０の芳香族炭化水素基（フェニル基等）を表す。なお、Ｒ^８及びＲ^９又はＲ^１１及びＲ^１２は、同一であってもよく、異なっていてもよい。また、ｉ、ｊ、ｋ、ｐ及びｑは、１〜８の整数を表す。 In addition, the method of incorporating the structural unit (II) in EVOH is not particularly limited, and examples thereof include a method of reacting a monovalent epoxy compound with EVOH obtained by a saponification reaction. Preferred examples of the monovalent epoxy compound include compounds represented by the following formulas (III) to (IX).

In the above formulas (III) to (IX), R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms (such as an alkyl group or an alkenyl group), An alicyclic hydrocarbon group having 3 to 10 carbon atoms (such as a cycloalkyl group or a cycloalkenyl group) or an aromatic hydrocarbon group having 6 to 10 carbon atoms (such as a phenyl group) is represented. R ⁸ and R ⁹ or R ¹¹ and R ¹² may be the same or different. Moreover, i, j, k, p, and q represent the integer of 1-8.

  Examples of the monovalent epoxy compound represented by the formula (III) include epoxy ethane (ethylene oxide), epoxy propane, 1,2-epoxybutane, 2,3-epoxybutane, and 3-methyl-1,2- Epoxybutane, 1,2-epoxypentane, 2,3-epoxypentane, 3-methyl-1,2-epoxypentane, 4-methyl-1,2-epoxypentane, 4-methyl-2,3-epoxypentane, 3-ethyl-1,2-epoxypentane, 1,2-epoxyhexane, 2,3-epoxyhexane, 3,4-epoxyhexane, 3-methyl-1,2-epoxyhexane, 4-methyl-1,2 -Epoxyhexane, 5-methyl-1,2-epoxyhexane, 3-ethyl-1,2-epoxyhexane, 3-propyl-1,2-epoxy Xanthone, 4-ethyl-1,2-epoxyhexane, 5-methyl-1,2-epoxyhexane, 4-methyl-2,3-epoxyhexane, 4-ethyl-2,3-epoxyhexane, 2-methyl- 3,4-epoxyhexane, 2,5-dimethyl-3,4-epoxyhexane, 3-methyl-1,2-epoxyheptane, 4-methyl-1,2-epoxyhexane, 5-methyl-1,2- Epoxyheptane, 6-methyl-1,2-epoxyheptane, 3-ethyl-1,2-epoxyheptane, 3-propyl-1,2-epoxyheptane, 3-butyl-1,2-epoxyheptane, 4-ethyl -1,2-epoxyheptane, 4-propyl-1,2-epoxyheptane, 6-ethyl-1,2-epoxyheptane, 4-methyl-2,3-epoxyheptane, -Ethyl-2,3-epoxyheptane, 4-propyl-2,3-epoxyheptane, 2-methyl-3,4-epoxyheptane, 5-methyl-3,4-epoxyheptane, 5-ethyl-3,4 -Epoxyheptane, 2,5-dimethyl-3,4-epoxyheptane, 2-methyl-5-ethyl-3,4-epoxyheptane, 1,2-epoxyheptane, 2,3-epoxyheptane, 3,4- Epoxyheptane, 1,2-epoxyoctane, 2,3-epoxyoctane, 3,4-epoxyoctane, 4,5-epoxyoctane, 1,2-epoxynonane, 2,3-epoxynonane, 3,4-epoxy Nonane, 4,5-epoxynonane, 1,2-epoxydecane, 2,3-epoxydecane, 3,4-epoxydecane, 4,5-epoxydecane, 5,6- Epoxy decane, 1,2-epoxy undecane, 2,3-epoxy undecane, 3,4-epoxy undecane, 4,5-epoxy undecane, 5,6-epoxy undecane, 1,2-epoxy undecane, 2,3-epoxy Dodecane, 3,4-epoxydodecane, 4,5-epoxydodecane, 5,6-epoxydodecane, 6,7-epoxydodecane, epoxyethylbenzene, 1-phenyl-1,2-propane, 3-phenyl-1,2, -Epoxypropane, 1-phenyl-1,2-epoxybutane, 3-phenyl-1,2-epoxypentane, 4-phenyl-1,2-epoxypentane, 5-phenyl-1,2-epoxypentane, 1- Phenyl-1,2-epoxyhexane, 3-phenyl-1,2-epoxyhexane, 4-phenyl-1,2, Epoxyhexane, 5-phenyl-1,2-epoxy hexane, 6-phenyl-1,2-epoxy hexane, and the like.

  Examples of the monovalent epoxy compound represented by the above formula (IV) include methyl glycidyl ether, ethyl glycidyl ether, n-propyl glycidyl ether, isopropyl glycidyl ether, n-butyl glycidyl ether, isobutyl glycidyl ether, tert-butyl glycidyl. Ether, 1,2-epoxy-3-pentyloxypropane, 1,2-epoxy-3-hexyloxypropane, 1,2-epoxy-3-heptyloxypropane, 1,2-epoxy-4-phenoxybutane, , 2-epoxy-4-benzyloxybutane, 1,2-epoxy-5-methoxypentane, 1,2-epoxy-5-ethoxypentane, 1,2-epoxy-5-propoxypentane, 1,2-epoxy- 5-butoxypentane, 1,2-d Xyl-5-pentyloxypentane, 1,2-epoxy-5-hexyloxypentane, 1,2-epoxy-5-phenoxypentane, 1,2-epoxy-6-methoxyhexane, 1,2-epoxy-6 Ethoxyhexane, 1,2-epoxy-6-propoxyhexane, 1,2-epoxy-6-butoxyhexane, 1,2-epoxy-6-heptyloxyhexane, 1,2-epoxy-7-methoxyheptane, 1, 2-epoxy-7-ethoxyheptane, 1,2-epoxy-7-propoxyheptane, 1,2-epoxy-7-butoxyheptane, 1,2-epoxy-8-methoxyoctane, 1,2-epoxy-8- Ethoxyoctane, 1,2-epoxy-8-butoxyoctane, glycidol, 3,4-epoxy-1-butanol, 4, -Epoxy-1-pentanol, 5,6-epoxy-1-hexanol, 6,7-epoxy-1-heptanol, 7,8-epoxy-1-octanol, 8,9-epoxy-1-nonanol, 9, Examples include 10-epoxy-1-decanol, 10,11-epoxy-1-undecanol, and the like.

  Examples of the monovalent epoxy compound represented by the above formula (V) include ethylene glycol monoglycidyl ether, propanediol monoglycidyl ether, butanediol monoglycidyl ether, pentanediol monoglycidyl ether, hexanediol monoglycidyl ether, heptanediol. Examples thereof include monoglycidyl ether and octanediol monoglycidyl ether.

  Examples of the monovalent epoxy compound represented by the formula (VI) include 3- (2,3-epoxy) propoxy-1-propene, 4- (2,3-epoxy) propoxy-1-butene, 5- (2,3-epoxy) propoxy-1-pentene, 6- (2,3-epoxy) propoxy-1-hexene, 7- (2,3-epoxy) propoxy-1-heptene, 8- (2,3- Epoxy) propoxy-1-octene and the like.

  Examples of the monovalent epoxy compound represented by the formula (VII) include 3,4-epoxy-2-butanol, 2,3-epoxy-1-butanol, 3,4-epoxy-2-pentanol, 2 , 3-epoxy-1-pentanol, 1,2-epoxy-3-pentanol, 2,3-epoxy-4-methyl-1-pentanol, 2,3-epoxy-4,4-dimethyl-1- Pentanol, 2,3-epoxy-1-hexanol, 3,4-epoxy-2-hexanol, 4,5-epoxy-3-hexanol, 1,2-epoxy-3-hexanol, 2,3-epoxy-4 , 4-Dimethyl-1-hexanol, 2,3-epoxy-4,4-diethyl-1-hexanol, 2,3-epoxy-4-methyl-4-ethyl-1-hexanol, 3,4-epoxy -5-methyl-2-hexanol, 3,4-epoxy-5,5-dimethyl-2-hexanol, 3,4-epoxy-2-heptanol, 2,3-epoxy-1-heptanol, 4,5-epoxy -3-heptanol, 2,3-epoxy-4-heptanol, 1,2-epoxy-3-heptanol, 2,3-epoxy-1-octanol, 3,4-epoxy-2-octanol, 4,5-epoxy -3-octanol, 5,6-epoxy-4-octanol, 2,3-epoxy-4-octanol, 1,2-epoxy-3-octanol, 2,3-epoxy-1-nonanol, 3,4-epoxy 2-nonanol, 4,5-epoxy-3-nonanol, 5,6-epoxy-4-nonanol, 3,4-epoxy-5-nonanol, 2,3-epoxy Si-4-nonanol, 1,2-epoxy-3-nonanol, 2,3-epoxy-1-decanol, 3,4-epoxy-2-decanol, 4,5-epoxy-3-decanol, 5,6- Examples include epoxy-4-decanol, 6,7-epoxy-5-decanol, 3,4-epoxy-5-decanol, 2,3-epoxy-4-decanol, 1,2-epoxy-3-decanol and the like.

  Examples of the monovalent epoxy compound represented by the above formula (VIII) include 1,2-epoxycyclopentane, 1,2-epoxycyclohexane, 1,2-epoxycycloheptane, 1,2-epoxycyclooctane, , 2-epoxycyclononane, 1,2-epoxycyclodecane, 1,2-epoxycycloundecane, 1,2-epoxycyclododecane and the like.

  Examples of the monovalent epoxy compound represented by the above formula (IX) include 3,4-epoxycyclopentene, 3,4-epoxycyclohexene, 3,4-epoxycycloheptene, 3,4-epoxycyclooctene, 3 , 4-epoxycyclononene, 1,2-epoxycyclodecene, 1,2-epoxycycloundecene, 1,2-epoxycyclododecene, and the like.

  Among the monovalent epoxy compounds, epoxy compounds having 2 to 8 carbon atoms are preferable. In particular, from the viewpoint of easy handling of the compound and reactivity with respect to EVOH, the carbon number of the monovalent epoxy compound is more preferably 2 to 6, and further preferably 2 to 4. The monovalent epoxy compound is particularly preferably a compound represented by the formula (III) or (IV) among the compounds represented by these formulas. Specifically, 1,2-epoxybutane, 2,3-epoxybutane, epoxypropane, epoxyethane, and glycidol are preferable from the viewpoint of reactivity to EVOH and gas barrier properties of the resulting multilayer structure. Propane and glycidol are particularly preferred.

  In the present invention, the ethylene-vinyl alcohol copolymer resin is obtained, for example, by polymerizing ethylene and a vinyl ester to obtain an ethylene-vinyl ester copolymer resin, and saponifying the ethylene-vinyl ester copolymer resin. . The modified ethylene-vinyl alcohol copolymer resin is, as described above, (1) in the polymerization of ethylene and vinyl ester, further copolymerizing monomers derived from the structural unit (I), (2) It is obtained by reacting a monovalent epoxy compound with EVOH obtained by a saponification reaction. Here, the polymerization method of the ethylene-vinyl alcohol copolymer resin and the modified ethylene-vinyl alcohol copolymer resin is not particularly limited, and for example, any of solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization may be used. Moreover, any of a continuous type and a batch type may be sufficient.

  Examples of vinyl esters that can be used for the polymerization include vinyl fatty acid such as vinyl acetate, vinyl propionate, and vinyl pivalate.

  Moreover, when manufacturing modified | denatured ethylene-vinyl alcohol copolymer resin, the monomer which can be copolymerized with these monomers other than ethylene and vinyl ester may be used preferably in a small amount. This copolymerizable monomer includes, in addition to the monomer derived from the above structural unit (I), other alkenes such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, and itaconic acid. Saturated carboxylic acid or its anhydride, salt, monoalkyl ester or dialkyl ester, etc .; Nitriles such as acrylonitrile and methacrylonitrile; Amides such as acrylamide and methacrylamide; Olefins such as vinyl sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid Sulfonic acid or a salt thereof; alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride and the like. Moreover, a vinyl silane compound can also be used as a monomer, and the amount of the vinyl silane compound introduced into the copolymer resin is preferably 0.0002 mol% or more and 0.2 mol% or less. Examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, γ-methacryloyloxypropylmethoxysilane, and the like. Among these vinylsilane compounds, vinyltrimethoxysilane and vinyltriethoxysilane are preferable.

  The solvent that can be used for the polymerization is not particularly limited as long as it is an organic solvent that can dissolve ethylene, vinyl ester, and ethylene-vinyl ester copolymer resin. Specific examples include alcohols such as methanol, ethanol, propanol, n-butanol and tert-butanol; dimethyl sulfoxide and the like. Among these, methanol is particularly preferable because removal and separation after the reaction is easy.

  Examples of the initiator that can be used for the polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis- (2,4-dimethylvaleronitrile), and 2,2′-azobis- (4-methoxy). -2,4-dimethylvaleronitrile), 2,2'-azobis- (2-cyclopropylpropionitrile) and other azonitrile initiators; isobutyryl peroxide, cumylperoxyneodecanoate, diisopropylperoxycarbonate And organic peroxide initiators such as di-n-propyl peroxydicarbonate, t-butylperoxyneodecanoate, lauroyl peroxide, benzoyl peroxide, and t-butyl hydroperoxide.

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

  After polymerization for a predetermined time or after reaching a predetermined polymerization rate, a polymerization inhibitor is added to the obtained copolymer resin solution as necessary, and unreacted ethylene gas is removed by evaporation. Remove. As a method for removing unreacted vinyl ester, for example, a copolymer resin solution is continuously supplied from the upper part of the tower packed with Raschig rings at a constant rate, and an organic solvent vapor such as methanol is blown from the lower part of the tower, A method of distilling a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester from the top and taking out a copolymer resin solution from which unreacted vinyl ester has been removed from the bottom of the column is employed.

  Next, an alkali catalyst is added to the copolymer resin solution to saponify the copolymer resin present in the solution. The saponification method can be either a continuous type or a batch type. Examples of the alkali catalyst include sodium hydroxide, potassium hydroxide, alkali metal alcoholate, and the like. The saponification conditions are, for example, in the case of batch type, the concentration of the alkali catalyst in the copolymer resin solution is about 10 to 50% by mass, the reaction temperature is about 30 to 65 ° C., and the amount of catalyst used is vinyl ester structural unit 1 It is preferable that about 0.02 to 1.0 mole per mole and saponification time is about 1 to 6 hours.

  The (modified) EVOH after the saponification reaction contains an alkali catalyst, by-product salts such as sodium acetate and potassium acetate, and other impurities. Therefore, it is preferable to remove these by neutralization and washing as necessary. . Here, when the (modified) EVOH after the saponification reaction is washed with water containing almost no metal ions such as ion-exchanged water, chloride ions, etc., part of sodium acetate, potassium acetate, etc. may remain. .

Filler As shown in FIG. 1, at least one layer 2 ′ of the resin composition layer 2 forming the multilayer structure of the present invention needs to contain a filler 4. Since the amount of the resin constituting the resin composition layer is reduced by including the filler 4 ', the resin composition layer can be substantially thinned (apparently thinned), resulting in higher toughness. The effect is obtained, and the durability of the multilayer structure 1 can be improved by the reinforcing action of the filler 4. Moreover, it is preferable that the resin composition layer containing the said filler in the said multilayer structure exists in three or more layers from the point which obtains the durability of the more excellent multilayer structure 1. FIG.

  Further, the content of the filler is 2 to 50 parts by mass with respect to 100 parts by mass of the gas barrier resin contained in the resin composition layer, from the viewpoint of obtaining durability of the multilayer structure. A range is preferable. When the content of the filler is less than 2 parts by mass, there is a risk that sufficient reinforcing action cannot be obtained and the durability of the desired multilayer structure may not be obtained, while the content exceeds 50 parts by mass. There is a risk that sufficient extrusion stability cannot be obtained.

  In addition, the filler is preferably an inorganic filler from the viewpoint that a good toughness effect can be obtained, the excellent durability point of the multilayer structure can be realized, and sufficient oxygen permeation suppressing power can be improved. .

  It is preferable to contain silica as a filler that can provide a good toughness effect and a reinforcing effect. From the viewpoint of the effect of toughening, as the type of silica, the average primary particle diameter determined from a transmission electron microscope (TEM) is 30 to 120 nm, preferably 40 to 100 nm.

  From the viewpoint of obtaining a good reinforcing action, it is preferable to contain carbon black as the filler. Examples of the carbon black include N660, N772, N762, N754, and the like. Carbon black having the following colloidal characteristics is more preferable. That is, the iodine adsorption amount (IA) is preferably 40 mg / g or less, and more preferably about 35 to 20 mg / g. The dibutyl phthalate oil absorption (DBP) is preferably 100 ml / 100 g or less, more preferably about 70 to 30 ml / 100 g. Here, IA of the colloidal characteristic is a value measured according to ASTM D1510-95, and DBP is a value measured according to ASTM D2414-97.

  Moreover, it is preferable that the said filler contains a layered or plate-shaped compound from the point of improving gas barrier property, bending resistance, and workability. The compound is not particularly limited as long as the shape thereof is flat (layered or plate-shaped), and can be appropriately selected according to the purpose. Specific examples of the compound include mica, clay, silica, alumina, and composites thereof. Among these, at least one selected from kaolin clay or a composite of hydrous silica and alumina is preferable. These compounds may be used alone or in combination of two or more, and commercially available products can be used as appropriate. Furthermore, the aspect ratio of the compound is preferably 3 or more and less than 30, and more preferably in the range of 8-20. Here, the aspect ratio means the ratio of the major axis to the thickness of the layered or plate-like compound.

  The particle size of the filler is preferably in the range of 0.2 to 8 μm. If the particle size is less than 0.2, because the particle size of the filler is too small, a sufficient toughness effect cannot be obtained, whereas, if the particle size exceeds 8 μm, the particle size is too large, This is because it may exist beyond the resin composition layer and may become a starting point of cracks. The particle diameter of the filler means the largest diameter among the fillers blended in the resin composition.

In addition, as shown in FIG. 3, the fillers contained in the resin composition layer have all the distances W of each other being 1 μm or less, and all the distances L from the boundary surface of the resin composition layer. Is preferably 1 μm or less. That is, it is preferable that the maximum values Wmax and Lmax of W and L are 1 μm or less. This is because the toughness effect due to the apparent thinning of the resin composition layer 2 ′ can be further enhanced.
Here, the maximum value Lmax of the distance L from the boundary surface of the resin composition layer and the maximum value Wmax of the distance W between the fillers are observed by cutting the multilayer structure as shown in FIG. The distances L1 to L5 from the periphery of the filler cross section to the resin composition layer interface or the distance W1 to W6 from the filler cross section in the vicinity are calculated for each filler, and the respective maximum values are calculated. Lmax and Wmax were obtained.

-Other compounding component You may mix | blend a radical crosslinking agent with the resin composition used for the said resin composition layer, and the elastomer used for an elastomer layer. When the resin composition contains a radical crosslinking agent, the crosslinking effect during irradiation with active energy rays can be enhanced, and the interlayer adhesion of the multilayer structure can be further improved. Moreover, it is also possible to reduce the irradiation amount of an active energy ray compared with the case where a radical crosslinking agent does not exist in a resin composition. The content of the radical crosslinking agent in the resin composition is preferably from 0.01 to 10% by mass, more preferably from 0.05 to 9% by mass, from the viewpoint of a balance between the crosslinking effect and economy, and 0.1 to 8%. More preferred is mass%. Examples of the radical crosslinking agent include trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, diethylene glycol diacrylate, neophenylene glycol diacrylate, and the like. In addition, these radical crosslinking agents may be used individually by 1 type, and may be used in combination of 2 or more type.

  You may mix | blend the 1 type or multiple types of compound chosen from a phosphoric acid compound, a carboxylic acid, and a boron compound with the resin composition used for the said resin composition layer.

  Specifically, the thermal stability at the time of melt molding of the multilayer structure can be improved by containing a phosphoric acid compound in the resin composition. It does not specifically limit as a phosphoric acid compound, For example, various acids, such as phosphoric acid and phosphorous acid, its salt, etc. are mentioned. The phosphate may be contained in any form of, for example, a first phosphate, a second phosphate, and a third phosphate, and the counter cation species is not particularly limited. Alkaline earth metal ions are preferred. In particular, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium hydrogen phosphate, or potassium hydrogen phosphate is preferred because of its high thermal stability improving effect.

  The lower limit of the phosphoric acid compound content (the phosphoric acid compound equivalent content of the phosphoric acid compound in the dry resin composition) is preferably 1 mass ppm, more preferably 10 mass ppm, and even more preferably 30 mass ppm. On the other hand, the upper limit of the content of the phosphoric acid compound is preferably 10,000 ppm by mass, more preferably 1,000 ppm by mass, and even more preferably 300 ppm by mass. If the content of the phosphoric acid compound is less than 1 ppm by mass, coloring during melt molding may become severe. In particular, since the tendency is remarkable when the heat histories are accumulated, a molded product obtained by molding the resin composition pellet may be poor in recoverability. On the other hand, if the content of the phosphoric acid compound exceeds 10,000 ppm by mass, there is a risk that gels and blisters during molding are likely to occur.

  Moreover, by containing carboxylic acid in a resin composition, the effect of controlling the pH of a resin composition, preventing gelation, and improving thermal stability is acquired. As the carboxylic acid, those having a pKa at 25 ° C. of 3.5 or more are preferable. When a carboxylic acid such as oxalic acid, succinic acid, benzoic acid, or citric acid having a pKa of less than 3.5 at 25 ° C. is contained, it becomes difficult to control the pH of the resin composition, and coloring resistance and interlayer adhesion are sufficient. May not be obtained. As such carboxylic acid, acetic acid or lactic acid is particularly preferable from the viewpoint of cost and the like.

  As a minimum of content of carboxylic acid (content of carboxylic acid in a dry resin composition), 1 mass ppm is preferred, 10 mass ppm is more preferred, and 50 mass ppm is still more preferred. On the other hand, the upper limit of the carboxylic acid content is preferably 10,000 ppm by mass, more preferably 1,000 ppm by mass, and even more preferably 500 ppm by mass. If the carboxylic acid content is less than 1 ppm by mass, coloring may occur during melt molding. On the other hand, if the content of carboxylic acid exceeds 10,000 ppm by mass, the interlayer adhesion may be insufficient.

Furthermore, the heat stability improvement effect is acquired by containing a boron compound in a resin composition. Specifically, for example, when a boron compound is added to a resin such as (modified) EVOH, a chelate compound is considered to be generated between (modified) EVOH and the boron compound, and by using such (modified) EVOH, It is possible to improve thermal stability and improve mechanical properties over normal (modified) EVOH. The boron compound is not particularly limited, and examples thereof include boric acids, boric acid esters, borates, and hydrogenated boric acids. Specifically, examples of boric acids include orthoboric acid (H ₃ BO ₃ ), 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, alkaline earth metal salts, and borax of the various boric acids. Of these, orthoboric acid is preferred.

  The lower limit of the boron compound content (the boron-converted content of the boron compound in the dry resin composition) is preferably 1 mass ppm, more preferably 10 mass ppm, and even more preferably 50 mass ppm. On the other hand, the upper limit of the boron compound content is preferably 2,000 ppm by mass, more preferably 1,000 ppm by mass, and even more preferably 500 ppm by mass. If the boron compound content is less than 1 ppm by mass, the effect of improving the thermal stability by adding the boron compound may not be obtained. On the other hand, if the content of the boron compound exceeds 2,000 mass ppm, gelation tends to occur, which may result in molding failure.

  The method for containing the phosphoric acid compound, carboxylic acid or boron compound in the resin composition is not particularly limited. For example, a method of adding and kneading the resin composition to the resin composition when preparing a pellet or the like of the resin composition. Is preferably employed. The method of adding to the resin composition is not particularly limited, but the method of adding as a dry powder, the method of adding in a paste impregnated with a solvent, the method of adding in a suspended state in a liquid, or dissolving in a solvent. The method of adding as a solution can be illustrated. Among these, from the viewpoint of homogeneous dispersion, a method of dissolving in a solvent and adding as a solution is preferable. The solvent used in these methods is not particularly limited, but water is preferably used from the viewpoints of solubility of the additive, cost merit, ease of handling, completeness of work environment, and the like. At the time of these additions, a metal salt, other additives, etc., which will be described later, can be added simultaneously.

  In addition, as another method of containing a phosphoric acid compound, a carboxylic acid or a boron compound, a method of immersing pellets or strands of a resin composition obtained by an extruder or the like in a solution in which those substances are dissolved in a solvent Is preferable in that the substance can be uniformly dispersed. Also in this method, water is preferably used as the solvent for the same reason. By dissolving a metal salt described later in this solution, the metal salt can be contained simultaneously with the phosphoric acid compound and the like.

  In the resin composition used for the resin composition layer, a compound having a conjugated double bond having a molecular weight of 1,000 or less may be blended. By containing such a compound, the hue of the resin composition is improved, and a multilayer structure having a good appearance can be produced. Examples of such a compound include a conjugated diene compound having a structure in which two carbon-carbon double bonds and three carbon-carbon single bonds are alternately connected, three carbon-carbon double bonds, and four carbon-carbon double bonds. Conjugated triene compound having a structure in which carbon-carbon single bonds are alternately connected (preferably 2,4,6-octatriene), 4 or more carbon-carbon double bonds and 5 or more carbon-carbon single bonds And conjugated polyene compounds having a structure in which and are alternately connected. In addition, the compound having a conjugated double bond may include a plurality of conjugated double bonds independently in one molecule, for example, a compound having three conjugated trienes in the same molecule such as tung oil. .

  Examples of the compound having a conjugated double bond include a carboxy group and a salt thereof, a hydroxyl group, an ester group, a carbonyl group, an ether group, an amino group, an imino group, an amide group, a cyano group, a diazo group, a nitro group, a sulfone group, and a sulfoxide. It may have various functional groups other than conjugated double bonds such as a group, sulfide group, thiol group, sulfonic acid group and salt thereof, phosphoric acid group and salt thereof, phenyl group, halogen atom and triple bond. Such a functional group may be directly bonded to the carbon atom in the conjugated double bond, or may be bonded to a position away from the conjugated double bond. Further, the multiple bond in the functional group may be in a position capable of conjugating with a conjugated double bond. For example, 1-phenylbutadiene having a phenyl group, sorbic acid having a carboxy group, etc. Included in compounds with heavy bonds.

  Specific examples of the compound having a conjugated double bond include, for example, 2,4-diphenyl-4-methyl-1-pentene, 1,3-diphenyl-1-butene, and 2,3-dimethyl-1,3-butadiene. 4-methyl-1,3-pentadiene, 1-phenyl-1,3-butadiene, sorbic acid, myrcene and the like.

  The conjugated double bond in the compound having a conjugated double bond is not only an aliphatic conjugated double bond such as 2,3-dimethyl-1,3-butadiene and sorbic acid, but also 2,4-diphenyl. Aliphatic and aromatic conjugated double bonds such as -4-methyl-1-pentene and 1,3-diphenyl-1-butene are also included. However, from the viewpoint of obtaining a multilayer structure having a more excellent appearance, a compound containing a conjugated double bond between aliphatic groups is preferable, and a conjugated double bond having a polar group such as a carboxy group and a salt thereof or a hydroxyl group is included. Also preferred are compounds. Further, a compound having a polar group and containing an aliphatic conjugated double bond is particularly preferable.

  The molecular weight of the compound having a conjugated double bond is preferably 1,000 or less. When the molecular weight exceeds 1,000, the surface smoothness and extrusion stability of the multilayer structure may be deteriorated.

  The lower limit of the content of the compound having a conjugated double bond having a molecular weight of 1,000 or less in the resin composition is preferably 0.1 mass ppm from the viewpoint of improving the effect exhibited by the addition of the compound, and 1 mass ppm. Is more preferable, 3 mass ppm is more preferable, and 5 mass ppm is particularly preferable. On the other hand, the upper limit of the content of such a compound is preferably 3,000 ppm by mass, more preferably 2,000 ppm by mass, further preferably 1,500 ppm by mass, and 1,000 ppm by mass from the viewpoint of improving the effect exhibited by the addition of the compound. Is particularly preferred.

  The method for adding the compound having a conjugated double bond to the resin composition is not particularly limited, but when the resin is (modified) EVOH, the compound after polymerization and before saponification is added. The method of adding is preferable in terms of improving surface smoothness and extrusion stability. The reason for this is not necessarily clear, but it is considered that the compound having a conjugated double bond has an action to prevent alteration of (modified) EVOH before saponification and / or during the saponification reaction.

  In addition to the resin, radical crosslinking agent, phosphoric acid compound, carboxylic acid, boron compound, compound having a conjugated double bond, the resin composition used for the resin composition layer includes a metal salt, a heat stabilizer, A wide variety of additives such as ultraviolet absorbers, antioxidants, colorants, fillers and the like can be appropriately selected and blended within a range that does not impair the object of the present invention. The content of additives other than the resin in the resin composition is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 10% by mass or less.

The resin composition in the resin composition layer has a melt viscosity (η _1A ) of 1 × 10 ² Pa · s to 1 × 10 ⁴ Pa · s at a temperature of 210 ° C. and a shear rate of 10 / second, a temperature The melt viscosity (η _2A ) at 210 ° C. and a shear rate of 1,000 / sec is 1 × 10 ¹ Pa · s to 1 × 10 ³ Pa · s, and the melt viscosity ratio (η _2A / η _1A ) Preferably satisfies the following formula (1A).
−0.8 ≦ (1/2) log ₁₀ (η _2A / η _1A ) ≦ −0.1 (1A)

If the melt viscosity (η _1A ) is less than 1 × 10 ² Pa · s, neck-in and film shaking will become significant during extrusion film formation by melt coextrusion lamination or melt extrusion, and the resulting multilayer structure and resin before lamination There is a possibility that the thickness unevenness and the reduction of the width of the composition layer become large, and it becomes impossible to obtain a multilayer structure having a uniform and intended size. On the other hand, when the melt viscosity (η _1A ) exceeds 1 × 10 ⁴ Pa · s, film breakage is likely to occur especially when performing melt coextrusion lamination or melt extrusion molding under high-speed take-up conditions exceeding 100 m / min. Thus, the high-speed film forming property is remarkably impaired, and die swell is likely to occur, which may make it difficult to obtain a thin multilayer structure or a resin composition layer before lamination.

Also, if the melt viscosity (η _2A ) is less than 1 × 10 ¹ Pa ·, neck-in and film shaking become significant during extrusion film formation by melt coextrusion lamination or melt extrusion, and the resulting multilayer structure or laminate There is a possibility that the thickness variation and the width reduction of the resin composition layer before the increase will be large. On the other hand, if the melt viscosity (η _2A ) exceeds 1 × 10 ³ Pa · s, the torque applied to the extruder becomes too high, and extrusion spots and weld lines may easily occur.

When the value of (1/2) log ₁₀ (η _2A / η _1A ) calculated from the melt viscosity ratio (η _2A / η _1A ) is smaller than −0.8, extrusion film formation by melt coextrusion lamination or melt extrusion Sometimes film breakage is likely to occur, and high-speed film-formability may be impaired. On the other hand, if the value of (1/2) log ₁₀ (η _2A / η _1A ) exceeds −0.1, neck-in or film swaying occurs during film formation by melt coextrusion lamination or melt extrusion, resulting in a multilayer structure obtained There is a risk that unevenness of thickness or reduction of width occurs in the body or the resin composition layer before lamination. From this point of view, the value of (1/2) log ₁₀ (η _2A / η _1A ) is more preferably −0.6 or more, and more preferably −0.2 or less. In addition, the value of (1/2) log ₁₀ (η _2A / η _1A ) in the above formula is the melt viscosity (η _1A ) and the melt in the logarithmic logarithmic graph with the melt viscosity as the vertical axis and the shear rate as the horizontal axis. It is determined as the slope of a straight line connecting two points of viscosity (η _2A ).

The resin composition in the resin composition layer has a viscosity behavior stability (M ₁₀₀ / M ₂₀ , where M _{20) in} relation to the melt kneading time and torque at at least one point at a temperature 10 to 80 ° C. higher than the melting point of the resin. it is preferred that the torque after 20 minutes from the start kneading, M ₁₀₀ is a range value of 0.5 to 1.5 of the representative of the torque after 100 minutes from the start kneading). The viscosity behavior stability value closer to 1 indicates that the viscosity change is smaller and the thermal stability (long run property) is better.

  The multilayer structure of the present invention preferably contains a metal salt in at least one of the layers constituting the resin composition layer. In this case, the interlayer adhesion of the multilayer structure can be greatly improved, and the multilayer structure has excellent durability. The reason why the interlayer adhesion can be improved by the inclusion of the metal salt is not necessarily clear, but it is considered that, for example, the bond generation reaction occurring between the resin composition layers is accelerated by the presence of the metal salt.

  The metal salt is not particularly limited, but an alkali metal salt, an alkaline earth metal salt, or a transition metal salt belonging to the fourth period of the periodic table is preferable from the viewpoint of further improving interlayer adhesion. Among these, alkali metal salts or alkaline earth metal salts are more preferable, and alkali metal salts are particularly preferable.

  The alkali metal salt is not particularly limited, and examples thereof include aliphatic carboxylates such as lithium, sodium, and potassium, aromatic carboxylates, phosphates, and metal complexes. Specific examples of the alkali metal salt include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and the like. Among these, sodium acetate, potassium acetate, and sodium phosphate are particularly preferable because they are easily available.

  Although it does not specifically limit as said alkaline-earth metal salt, For example, acetate, such as magnesium, calcium, barium, beryllium, or phosphate is mentioned. Among these, magnesium or calcium acetate or phosphate is particularly preferable because it is easily available. When such an alkaline earth metal salt is contained, there is an advantage that the amount of heat-degraded resin adhering to the die of the molding machine during melt molding can be reduced.

  The metal salt of the transition metal belonging to the fourth period of the periodic table is not particularly limited, but for example, carboxylates and phosphates such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc And acetylacetonate salts.

  The lower limit of the content of the metal salt (content in terms of metal element in the multilayer structure) is preferably 1 mass ppm, more preferably 5 mass ppm, further preferably 10 mass ppm, and particularly preferably 20 mass ppm. . On the other hand, the upper limit of the content of the metal salt is preferably 10,000 ppm by mass, more preferably 5,000 ppm by mass, further preferably 1,000 ppm by mass, and particularly preferably 500 ppm by mass. If the content of the metal salt is less than 1 mass ppm, the effect of improving interlayer adhesion may be reduced. On the other hand, when the content of the metal salt exceeds 10,000 ppm by mass, the appearance of the multilayer structure may be deteriorated.

  The method for containing the metal salt in the resin composition forming the resin composition layer or the elastomer composition forming the elastomer layer is not particularly limited, and the phosphoric acid compound in the resin composition as described above A method similar to the method containing the above can be adopted.

  In the multilayer structure of the present invention, the peel resistance between different resin composition layers is preferably 20 N / 25 mm or more, more preferably 25 N / 25 mm or more, and further preferably 30 N / from the viewpoint of interlayer adhesion. It is 25mm or more. Here, the peel resistance is a value measured by a T-type peel test in accordance with JIS K 6854 under an atmosphere of 23 ° C. and 50% RH and a tensile speed of 50 mm / min.

(Manufacturing method of multilayer structure)
The method for producing the multilayer structure of the present invention is not particularly limited as long as the resin composition layer and the elastomer layer can be laminated and adhered satisfactorily. For example, co-extrusion, lamination, coating, bonding And known methods such as adhesion. Among them, as a method for producing a multilayer structure of the present invention, a plurality of resin compositions and elastomers are prepared, and a multilayer structure having a resin composition layer is produced by a multilayer coextrusion method using these compositions. The method is preferred. This is because productivity is high and interlayer adhesion is excellent.

  In the multilayer coextrusion method, the resin or resin composition forming the resin composition layer is heated and melted and supplied from different extruders and pumps to the extrusion dies through the respective flow paths, and from the extrusion dies to the multilayers. The multilayer structure of the present invention is formed by laminating and bonding after being extruded. As this extrusion die, for example, a multi-manifold die, a field block, a static mixer or the like can be used.

  In the multilayer structure of the present invention, a support layer for supporting the laminate may be laminated on both sides or one side of the laminate composed of the resin composition layer. The support layer is not particularly limited, and for example, a synthetic resin layer that is usually used as a support layer can be used. In addition, it does not specifically limit as a lamination | stacking method to the resin composition layer or elastomer layer of a support layer, For example, the adhesion method by an adhesive agent, the extrusion lamination method, etc. are mentioned.

(Inner liner)
Next, the inner liner for a pneumatic tire of the present invention and the pneumatic tire of the present invention will be described in detail with reference to the drawings. The inner liner for a pneumatic tire according to the present invention is characterized by using the multilayer structure described above, and the pneumatic tire according to the present invention is provided with the inner liner.
FIG. 2 is a partial cross-sectional view of an example of the pneumatic tire of the present invention. The tire shown in FIG. 2 has a pair of bead portions 7 and a pair of sidewall portions 8, and a tread portion 9 connected to both sidewall portions 8, and extends in a toroid shape between the pair of bead portions 7. A carcass 10 that reinforces each of these parts 7, 8, and 9, and a belt 11 formed of two belt layers disposed on the outer side in the tire radial direction of the crown part of the carcass 10. An inner liner 12 is disposed on the inner surface of the tire.

  In the illustrated example of the tire, the carcass 10 includes a main body portion extending in a toroidal shape between a pair of bead cores 13 embedded in the bead portion 7, and around each bead core 13 from the inner side to the outer side in the tire width direction. In the tire of the present invention, the number of plies and the structure of the carcass 10 are not limited to this.

  In the illustrated tire, the belt 11 includes two belt layers. However, in the tire of the present invention, the number of belt layers constituting the belt 11 is not limited thereto. Here, the belt layer is usually composed of a rubberized layer of a cord extending obliquely with respect to the tire equatorial plane. In the two belt layers, the cords constituting the belt layer intersect with each other with the equator plane interposed therebetween. Thus, the belt 11 is configured by being laminated. Further, the tire of the illustrated example includes a belt reinforcing layer 14 disposed so as to cover the entire belt 11 outside the belt 11 in the tire radial direction. However, the tire of the present invention includes the belt reinforcing layer 14. The belt reinforcing layer having another structure may be provided. Here, the belt reinforcing layer 14 is usually composed of a rubberized layer of cords arranged substantially parallel to the tire circumferential direction.

(Pneumatic tire)
The pneumatic tire of the present invention can be manufactured by applying the above-described multilayer structure to the inner liner 12 and using a conventional method. In the pneumatic tire of the present invention, as the gas filled in the tire, normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Synthesis Example 1: EVOH)
In a polymerization tank having a cooling device and a stirrer, 20000 parts by mass of vinyl acetate, 1020 parts by mass of methanol, and 3.5 parts by mass of 2,2′-azobis- (4-methoxy-2,4-dimethylvaleronitrile) as a polymerization initiator After purging with nitrogen and stirring, ethylene was introduced, the internal temperature was adjusted to 60 ° C., the ethylene pressure was controlled to 5.9 MPa, the temperature and pressure were maintained for 4 hours, and polymerization was performed while stirring. Next, 10 parts by mass of sorbic acid (SA) (0.0005% by mass relative to the charged vinyl acetate) was dissolved in methanol to prepare a methanol solution of 1.5% by mass of sorbic acid, and this was added. The polymerization rate was 30% based on the charged vinyl acetate. The copolymerization reaction solution obtained after the polymerization is supplied to a tower packed with Raschig rings, and unreacted vinyl acetate is removed from the top of the tower by introducing methanol vapor from the bottom of the tower, and then 40% by mass of methanol of the copolymer. A solution was obtained. The copolymer had an ethylene unit content of 44 mol% and a vinyl acetate unit content of 56 mol%.

  The methanol solution of the copolymer thus obtained was introduced into a saponification reactor, and then a sodium hydroxide / methanol solution (85 g / L) was added so as to be 0.5 equivalent to the vinyl acetate component in the copolymer. Further, methanol was added to adjust the copolymer concentration in the solution to 15% by mass. The temperature in the reactor was raised to 60 ° C., and the reaction was carried out for 5 hours while blowing nitrogen gas into the reactor. Thereafter, the reaction solution was neutralized with acetic acid to stop the reaction, and the contents were taken out from the reactor and allowed to stand at room temperature. As a result, particulate EVOH was precipitated. The precipitated particles were drained with a centrifuge, and an operation of adding a large amount of water to drain the liquid was repeated to obtain EVOH having a saponification degree of 99.5%.

  The obtained EVOH was treated at a bath ratio of 20 with an aqueous solution containing acetic acid, phosphoric acid and orthoboric acid (OBA) (dissolving 0.3 g of acetic acid, 0.06 g of phosphoric acid and 0.35 g of orthoboric acid in 1 L of an aqueous solution), and after drying. And pelletized with an extruder to obtain EVOH pellets. The MFR of the EVOH pellets was 4.6 g / 10 min (190 ° C., 21.18 N load). Further, the acetic acid content of the pellet was 90 mass ppm, the phosphoric acid compound content was 43 mass ppm in terms of phosphate radical, and the boron compound content was 260 mass ppm in terms of boron.

(Synthesis Example 2: Modified EVOH)
In a pressurized reaction layer, 2 parts by weight of an ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% and a saponification degree of 99.9% and 8 parts by weight of N-methyl-2-pyrrolidone were charged and stirred at 120 ° C. for 2 hours. By doing so, the ethylene-vinyl alcohol copolymer was completely dissolved.
To this was added 0.4 part by weight of epoxypropane as an epoxy compound, and then heated at 160 ° C. for 4 hours.
After the heating, it was precipitated in 100 parts by weight of distilled water, and N-methyl-2-pyrrolidone and unreacted epoxypropane were sufficiently washed with a large amount of distilled water to obtain a modified ethylene-vinyl alcohol copolymer.
Further, the obtained modified ethylene-vinyl alcohol copolymer was finely divided to a particle size of about 2 mm with a pulverizer, and then sufficiently washed with a large amount of distilled water again.
The washed particles were vacuum-dried at room temperature for 8 hours, and then melted at 200 ° C. using a twin-screw extruder and pelletized.

(Samples 1 to 18 of Examples and Comparative Examples)
After preparing the resin composition for forming the resin composition layer shown in Table 1, and making the resin composition contain the filler in the content shown in Table 1, it was laminated in the number of layers shown in Table 1. In order to form a multilayer structure, a 210 ° C. melt was supplied from the co-extruder to the feed block, and the melt was extruded and merged from the feed block to produce a multilayer structure. The melt is changed from the feed block so that the thickness of each layer of the multilayer structure becomes uniform by changing the flow path of each layer in the feed block so that it gradually becomes thicker from the surface side toward the center side. It was pushed out.
Moreover, the shape of the slit was designed so that the layer thicknesses of the adjacent resin composition layers were substantially the same. The multilayer structure thus obtained was rapidly cooled and solidified on a casting drum which was kept at a surface temperature of 25 ° C. and electrostatically applied. The cast film obtained by rapid cooling and solidification was pressure-bonded onto a release paper and wound up. In addition, the flow path shape and the total discharge amount were set so that the time from when the melts were merged to when rapidly solidified on the casting drum was about 4 minutes.
In this example, all the resin composition layers include a filler.

  The cast film obtained as described above is subjected to cross-sectional observation with DIGITAL MICROSCOPE VHX-900 (manufactured by KEYENCE) or electron microscope VE-8800 (manufactured by KEYENCE), and the average thickness of the resin composition layer / multilayer structure The thickness, the distance from the periphery of the filler to the resin composition layer / elastomer layer interface, and the distance from the periphery of the filler to the periphery of the nearby filler were determined. The results are shown in Table 1.

  Next, for this cast film, an electron beam accelerator [Nisshin High Voltage Co., Ltd., Curetron EB200-100] was used, and each sample was irradiated with an electron beam having an irradiation dose shown in Table 1 at an acceleration voltage of 200 kV. Irradiation gave a cross-linked multilayer film.

  Next, for the multilayer film sample prepared as described above, gas barrier properties, crack resistance, peeling resistance in the film layer, presence or absence of cracks after a low-temperature drum running test, and internal pressure retention were evaluated by the following methods. did. The results are shown in Table 1.

(1) Gas barrier property The film was conditioned at 20 ° C. and 65% RH for 5 days. Using the obtained two humidity-adjusted films, the oxygen transmission coefficient was measured under the conditions of 20 ° C. and 65% RH using GTR-30X manufactured by GTR Tech, and the average value was obtained.
In the table, the average value of the sample 1 of the comparative example is shown as an index, and the lower the index value, the better the gas barrier property.

(2) Crack resistance
50 sheets of the above-mentioned films cut to 21cm x 30cm were prepared, and each cut film was conditioned at 0 ° C for 7 days, and then used in accordance with ASTM F392-74, using a gelbo flex tester manufactured by Rigaku Corporation. Bending 50, 75, 100, 125, 150, 175, 200, 225, 250, 300, 400, 500, 600, 700, 800, 1000 And bent 1500 times, the number of pinholes was measured. In each bending number, the measurement was performed 5 times, and the average value was defined as the number of pinholes. Taking the number of bends (P) on the horizontal axis and the number of pinholes (N) on the vertical axis, plotting the above measurement results, finding the number of bends (Np1) when the number of pinholes is one by extrapolation, and using significant figures Two digits were used. However, for a film in which pinholes were not observed after 1500 bends, the number of bends was increased every 500 times, and the number of bends in which pinholes were seen was defined as Np1.
About evaluation, it shows by an index value when the number of times of bending of comparative example 1 is set to 100, and it shows that the number of times of bending is larger and the crack resistance is higher as the numerical value is larger.

(3) Presence or absence of crack after low temperature drum running test Using the above film as an inner liner, a pneumatic tire (195 / 65R15) having a structure shown in FIG. Next, the tire was pushed at a pressure of 6 kN on a rotating drum corresponding to a speed of 80 km / h at an air pressure of 140 kPa in an atmosphere of −30 ° C. for 10,000 km. The appearance of the inner liner of the tire after running the drum was visually observed to evaluate the presence or absence of cracks.

(4) Internal Pressure Retention Property The tire was run for 10,000 km in an atmosphere of −30 ° C. with an air pressure of 140 kPa on a rotating drum corresponding to a speed of 80 km / h with a load of 6 kN. Then, after running the tire (test tire) on a 6JJ × 15 rim, the inner pressure was set to 240 kPa and left for 3 months. Measure the internal pressure after 3 months and use the following formula:
Internal pressure retention = ((240−b) / (240−a)) × 100
The internal pressure retention was evaluated using [wherein, a is the internal pressure (kPa) after 3 months of the test tire and b is the internal pressure (kPa) after 3 months of the test tire of Sample 1 of the comparative example].
In the table, the value of Sample 1 of the comparative example was set to 100, and other values were indexed. The larger the index value, the better the internal pressure retention.

* 1 J. M.M. Made by Huber, Polyfil DL (aspect ratio 8).
* 2 Nisseki Calcium Co., Ltd., Crown Cray-S.
* 3 ZEOSIL 125GR, manufactured by Rhodia.
* 4 Kuraray Co., Ltd., Clamiron 3190.
* 5 UBESTA XPA manufactured by Ube Industries, Ltd.
* 6 Toray Industries, Inc., CM1061.
* 7 Iran Petrochemical, PARS.
* 8 Saran manufactured by Asahi Dow Corporation.

  From the results of Tables 1 and 2, it can be seen that the multilayer structures of the examples can achieve both gas barrier properties and crack resistance compared to the multilayer structures of the comparative examples. In addition, the multilayer structures of the examples are excellent in durability at low temperatures. Furthermore, since the thickness of the resin composition layer is thin, it can be seen that it contributes to weight reduction of the tire.

  According to the present invention, it is possible to provide a multilayer structure having a light weight while having excellent gas barrier properties and crack resistance. Moreover, it becomes possible to provide an inner liner for a pneumatic tire using such a multilayer structure and a pneumatic tire including the inner liner. Thereby, it is industrially useful in that a pneumatic tire having higher gas barrier properties and lower fuel consumption can be obtained as compared with the conventional one.

DESCRIPTION OF SYMBOLS 1 Multilayer structure 2 Resin composition layer 3 Elastomer layer 4 Filler 7 Bead part 8 Side wall part 9 Tread part 10 Carcass 11 Belt 12 Inner liner 13 Bead core

Claims (9)

A multilayer structure in which a resin composition layer and an elastomer layer are alternately laminated in a total of 7 or more layers,
The resin composition layer has a single layer average thickness of 0.001 to 10 μm, the elastomer layer has a single layer average thickness of 0.001 to 40 μm,
At least 1 layer of the said resin composition layers contains a filler, The multilayer structure characterized by the above-mentioned.   The filler contained in the resin composition layer has a distance between the circumferences of the fillers of 1 μm or less, and a distance from the periphery of the important material to the boundary surface of the resin composition layer is 1 μm or less. The multilayer structure according to claim 1.   The multilayer structure according to claim 1, wherein the filler is an inorganic filler.   The multilayer structure according to claim 3, wherein the layered or plate-like compound is a composite of hydrous silica and alumina.   The multilayer structure according to claim 2, wherein the inorganic filler is a layered or plate-like compound, or silica or carbon black.   The multilayer structure according to claim 1, wherein the resin composition layer includes a gas barrier resin. 7. The multilayer structure according to claim 6, wherein the resin composition layer has an oxygen permeability at 20 ° C. and 65 RH% of 8.0 × 10 ⁻¹² cm ³ · cm ² · sec · cmHg or less. body.   The inner liner for pneumatic tires using the multilayer structure in any one of Claims 1-7.   A pneumatic tire comprising the inner liner for a pneumatic tire according to claim 8.

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