JP2011105046A - Inner liner for pneumatic tire, method of manufacturing the same and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an inner liner for a pneumatic tire including a layer composed of a resin composition of uniformly dispersing a viscoelastic body, the inner liner manufactured by this manufacturing method and the pneumatic tire using this inner liner. <P>SOLUTION: This manufacturing method of the inner liner for the pneumatic tire includes a process of preparing the viscoelastic body by blending a multipoint modified viscoelastic body of introducing a plurality of functional groups reacting with a hydroxyl group and at least one of a partially modified viscoelastic body and an unmodified viscoelastic body of introducing a functional group reacting with a hydroxyl group by one or less into one molecule chain, a process of preparing the resin composition by dispersing the prepared viscoelastic body in a matrix composed of an ethylene-vinyl alcohol copolymer or a modified ethylene-vinyl alcohol copolymer and a process of forming the layer composed of the prepared resin composition. The inner liner is manufactured by this manufacturing method, and the pneumatic tire uses this inner liner. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an inner liner for a pneumatic tire, which can produce an inner liner having high productivity and gas barrier properties at low cost. The present invention also relates to an inner liner for a pneumatic tire manufactured using the manufacturing method and a pneumatic tire using the inner liner.

  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 barrier layer on the tire inner surface in order to maintain the internal pressure of the tire. However, these rubber compositions using butyl rubber as the main raw material have low air barrier properties, so when such a rubber composition is used for the inner liner, the thickness of the inner liner has to be about 1 mm. For this reason, the weight of the inner liner in the tire is about 5%, which is an obstacle to reducing the weight of the tire and improving the fuel efficiency of the automobile.

  On the other hand, an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as “EVOH”) is known to have excellent gas barrier properties. The EVOH has an air permeation amount that is 1/100 or less of the above butyl rubber composition for inner liners. Therefore, when used for an inner liner, the EVOH significantly increases the internal pressure retention of a tire even with a thickness of 100 μm or less. In addition to being able to improve, it is possible to reduce the weight of the tire.

  There are many resins that have a lower air permeability than the butyl rubber, but if the air permeability is about one-tenth that of a butyl inner liner, the internal pressure retention effect can be improved unless the thickness exceeds 100 μm. small. On the other hand, when the thickness exceeds 100 μm, the effect of reducing the weight of the tire is small, and the inner liner is broken or cracked in the inner liner due to deformation at the time of bending of the tire, so that the barrier property is maintained. It becomes difficult.

  On the other hand, when the EVOH is used, the inner liner is difficult to break due to bending deformation at the time of rolling of the tire, cracks are hardly generated, and the inner liner can be made to have a thickness of 100 μm or less. 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, Japanese Unexamined Patent Publication No. 6-40207 (Patent Document 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, In some cases, the material may break or crack. 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. As means for solving this problem, Japanese Patent Application Laid-Open No. 2002-52904 (Patent Document 2) describes an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 70 mol% and a saponification degree of 85% or more of 60 to 99 wt. And a resin composition comprising 1 to 40% by weight of a hydrophobic plasticizer is disclosed in an inner liner.

  Furthermore, JP 2004-176048 A (Patent Document 3) reacts 1 to 50 parts by weight of an epoxy compound with 100 parts by weight of an ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 50 mol%. A technique of using the obtained modified ethylene-vinyl alcohol copolymer for an inner liner is disclosed, and the inner liner has a gas barrier property while maintaining a gas barrier property as compared with a conventional inner liner for EVOH. It has a high degree of bending resistance.

  Furthermore, International Publication No. 2008/013152 (Patent Document 4) discloses Young's modulus at 23 ° C. in a matrix composed of a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene-vinyl alcohol copolymer. Discloses an inner liner for a pneumatic tire including at least a layer made of a resin composition in which a soft resin smaller than a modified ethylene-vinyl alcohol copolymer is dispersed. And in patent document 4, in order for a flexible resin to disperse | distribute uniformly in a modified ethylene-vinyl alcohol copolymer, it is preferable that the flexible resin has a functional group which reacts with a hydroxyl group.

JP-A-6-40207 JP 2002-52904 A JP 2004-176048 A International Publication No. 2008/013152

  However, in the technique described in International Publication No. 2008/013152, when the flexible resin has a large number of functional groups that react with hydroxyl groups, the flexible resin and the modified ethylene-vinyl alcohol copolymer gel, May not be uniformly dispersed in the modified ethylene-vinyl alcohol copolymer.

  Therefore, it is possible to improve the dispersibility of the viscoelastic body in the resin composition with respect to the inner liner including a layer made of a resin composition in which a viscoelastic body (soft resin) having a large number of functional groups that react with hydroxyl groups is dispersed. There has been a demand for a method for producing an inner liner for a pneumatic tire. Moreover, the inner liner manufactured with this manufacturing method and the pneumatic tire using this inner liner were also calculated | required.

  An object of the present invention is to advantageously solve the above-mentioned problems, and an inner liner for a pneumatic tire according to the present invention includes an ethylene-vinyl alcohol copolymer (A) or an ethylene-vinyl alcohol copolymer ( From the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B) in a matrix comprising the modified ethylene-vinyl alcohol copolymer (B) obtained by reacting A) An inner liner including at least a layer made of a resin composition (D) in which a viscoelastic body (C) having a low Young's modulus at 0 ° C. is dispersed, wherein the viscoelastic body (C) has a functional group that reacts with a hydroxyl group. Multiple modified viscoelastic bodies (E) introduced multiple times and partially modified viscoelastic bodies (F) in which one or less functional groups that react with hydroxyl groups are introduced in one molecular chain And characterized in that it comprises at least one native viscoelastic body (G). Thus, as a viscoelastic body (C), if a multipoint modified viscoelastic body (E) and at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G) are blended, Multi-point modified viscoelastic body (E) and ethylene-vinyl alcohol copolymer weight while ensuring reinforcement by interfacial reaction between viscoelastic body (C) and ethylene-vinyl alcohol copolymer (A) or modified EVOH (B) Gelation with the union (A) or the modified EVOH (B) can be prevented, and the dispersibility of the viscoelastic body (C) in the matrix can be improved. Therefore, an inner liner having high processability, productivity, barrier properties, and crack resistance can be provided.

  In addition, the method for producing an inner liner for a pneumatic tire according to the present invention comprises a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene-vinyl alcohol copolymer (A) or an ethylene-vinyl alcohol copolymer (A). A viscoelastic body (C) having a lower Young's modulus at 23 ° C. than that of the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B) is dispersed in a matrix composed of the combination (B). A multi-point modified viscoelastic body (E) in which a plurality of functional groups that react with hydroxyl groups are introduced, and a functional group that reacts with hydroxyl groups, and a method for producing an inner liner comprising at least a layer comprising the resin composition (D) Is blended with at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G) in which 1 or less is introduced into one molecular chain. The step of preparing the viscoelastic body (C) and the prepared viscoelastic body (C) in a matrix comprising the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B). It includes a step of preparing the resin composition (D) by dispersing and a step of forming a layer comprising the prepared resin composition (D). Thus, the viscoelastic body (C) obtained by previously blending the multipoint modified viscoelastic body (E) with at least one of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) in the matrix. The multi-point modified viscoelastic body (E) and the multi-point modified viscoelastic body (E) are obtained while ensuring reinforcement by interfacial reaction between the viscoelastic body (C) and the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B). Gelation with the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B) can be prevented, and the dispersibility of the viscoelastic body (C) in the matrix can be improved. Therefore, an inner liner having high processability, productivity, barrier properties and crack resistance can be produced.

  Here, in the manufacturing method of the inner liner for pneumatic tires of the present invention, the blending amount of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) in the viscoelastic body (C). Is preferably 20 to 99% by mass. The total (F + G) of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) in the viscoelastic body (C) is 20% by mass or more, that is, a large amount in the viscoelastic body (C). If the amount (E / C) of the point-modified viscoelastic body (E) is 80% by mass or less, the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B) and the multi-point modified viscoelastic body (E) This is because the gelation can be prevented more reliably. Further, the total (F + G) of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) in the viscoelastic body (C) is 99% by mass or less, that is, in the viscoelastic body (C). If the amount (E / C) of the multipoint modified viscoelastic body (E) is 1% by mass or more, the viscoelastic body (C) and the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B) This is because sufficient reinforcement by the interfacial reaction can be ensured.

  In the method for producing an inner liner for a pneumatic tire of the present invention, the amount of the unmodified viscoelastic body (G) in the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G). (G / F + G) is preferably 10 to 95% by mass. If the unmodified viscoelastic body (G) is 10% by mass or more, gelation of the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B) and the viscoelastic body (C) is more reliably prevented. Because it can. If the unmodified viscoelastic body (G) is 95% by mass or less, the interfacial reaction between the viscoelastic body (C) and the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B) proceeds, and the interface This is because the reinforcing property is increased.

  Furthermore, in the manufacturing method of the inner liner for pneumatic tires of the present invention, the viscoelastic body (C) is prepared by the multipoint modified viscoelastic body (E) and the partially modified viscoelastic body (F). It is preferable to carry out melt kneading with at least one of the unmodified viscoelastic body (G). By melt-kneading, the multi-point modified viscoelastic body (E) can be effectively diluted, and gelation is prevented during kneading with the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B). Because it can.

  Moreover, in the manufacturing method of the inner liner for pneumatic tires of this invention, the said viscoelastic body (C) is prepared by the said multipoint modified viscoelastic body (E) and the said partially modified viscoelastic body (F). It is preferable to carry out by dissolving and mixing at least one of the unmodified viscoelastic body (G) in a solvent and then removing the solvent. By removing the solvent after dissolution and mixing, it is possible to blend uniformly and to prevent gelation when kneaded with the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B). .

  And the inner liner for pneumatic tires of this invention was manufactured using the manufacturing method in any one of said. Thus, if an inner liner is manufactured using the manufacturing method mentioned above, an inner liner with high productivity, barrier property, and crack resistance can be obtained.

  The pneumatic tire of the present invention is characterized by using the above inner liner for a pneumatic tire. Thus, if the said inner liner is used, the lightweight pneumatic tire with the high internal pressure retention property of the tire at the time of a new article and after driving | running | working can be obtained at low cost.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the inner liner for pneumatic tires which can improve the dispersibility of the viscoelastic body in a resin composition, and can manufacture an inner liner with high productivity, barrier property, and crack resistance. Can be provided. In addition, according to the present invention, it is possible to provide an inner liner for a pneumatic tire having high productivity, barrier properties and crack resistance, and a lightweight pneumatic tire having a high internal pressure retaining property of a tire when new and after running. it can.

It is a fragmentary sectional view of an example of the pneumatic tire of the present invention. It is an expanded partial sectional view of other examples of the pneumatic tire of the present invention. It is an expanded partial sectional view of another example of the pneumatic tire of the present invention. It is a fragmentary sectional view of the other example of the pneumatic tire of the present invention.

<Inner liner for pneumatic tires>
Below, the inner liner for pneumatic tires of the present invention will be explained in detail. The inner liner for a pneumatic tire of the present invention comprises an ethylene-vinyl alcohol copolymer (A) or a modified ethylene-vinyl alcohol copolymer (B) obtained by reacting an ethylene-vinyl alcohol copolymer (A). A resin composition in which a viscoelastic body (C) having a Young's modulus at 23 ° C. lower than that of the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B) is dispersed in the matrix. A multi-point modified viscoelastic body (E) in which a plurality of functional groups that react with hydroxyl groups are introduced as a viscoelastic body (C), and a functional group that reacts with hydroxyl groups. And at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G), wherein one or less is introduced into one molecular chain. . Specifically, for example, the viscoelastic body (C) includes a multipoint modified viscoelastic body (E) in which a plurality of functional groups that react with a hydroxyl group are introduced into one molecular chain, and a functional group that reacts with a hydroxyl group. It can be prepared by blending at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G) introduced in the chain by 1 or less. Thus, the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B) obtained by reacting the ethylene-vinyl alcohol copolymer (A) in the resin containing the ethylene-vinyl alcohol copolymer (A). A resin composition (D) in which a viscoelastic body (C) having a lower Young's modulus at 23 ° C. than the vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B) is dispersed is used for the inner liner. Thus, it is possible to provide an inner liner that is excellent in gas barrier properties and flex resistance, and can reduce the weight of the tire while improving the internal pressure retention of the tire when new and after running. If the multi-point modified viscoelastic body (E) and at least one of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) are previously blended and then dispersed in the matrix, Multipoint modified viscoelastic body (E) and ethylene-vinyl alcohol copolymer while ensuring reinforcement by interfacial reaction between elastic body (C) and ethylene-vinyl alcohol copolymer (A) or modified EVOH (B) Gelling with (A) or modified EVOH (B) can be prevented, and the dispersibility of the viscoelastic body (C) in the matrix can be improved.

  Here, for example, the modified ethylene-vinyl alcohol copolymer (B) obtained by reacting the ethylene-vinyl alcohol copolymer (A) with an epoxy compound has a lower elastic modulus than that of ordinary EVOH. Moreover, an elastic modulus can further be reduced by disperse | distributing a viscoelastic body (C). Therefore, the resin composition (D) in which the viscoelastic body (C) is dispersed in the matrix composed of the modified ethylene-vinyl alcohol copolymer (B) has a greatly reduced elastic modulus. The inner liner using the composition (D) has high rupture resistance at the time of bending and hardly generates cracks.

(Ethylene-vinyl alcohol copolymer)
The ethylene-vinyl alcohol copolymer (A) preferably has an ethylene content of 25 to 50 mol%, more preferably 30 to 48 mol%, and further preferably 35 to 45 mol%. preferable. If the ethylene content is less than 25 mol%, the bending resistance, fatigue resistance and melt moldability may be deteriorated. On the other hand, if it exceeds 50 mol%, the gas barrier properties may not be sufficiently secured. The ethylene-vinyl alcohol copolymer (A) preferably has a saponification degree of 90% or more, more preferably 95% or more, and even more preferably 99% or more. If the degree of saponification is less than 90%, gas barrier properties and thermal stability during molding may be insufficient. Furthermore, the ethylene-vinyl alcohol copolymer (A) preferably has a melt flow rate (MFR) of 190 to 30 ° C. and 0.1 to 30 g / 10 min under a load of 2160 g, and 0.3 to 25 g / 10. More preferably, it is minutes.

(Modified ethylene-vinyl alcohol copolymer)
In the present invention, the production method of the modified ethylene-vinyl alcohol copolymer (B) is not particularly limited, but a production method in which the ethylene-vinyl alcohol copolymer (A) and an epoxy compound are reacted in a solution is preferable. It is mentioned in. More specifically, a modified ethylene-vinyl alcohol copolymer is prepared by adding an epoxy compound to the ethylene-vinyl alcohol copolymer (A) solution in the presence of an acid catalyst or an alkali catalyst, preferably in the presence of an acid catalyst, and reacting. A coalescence (B) can be manufactured. Examples of the reaction solvent include aprotic polar solvents such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Examples of the acid catalyst include p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, and boron trifluoride. Examples of the alkali catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, Examples include sodium methoxide. The catalyst amount is preferably in the range of 0.0001 to 10 parts by mass with respect to 100 parts by mass of the ethylene-vinyl alcohol copolymer (A).

  As said epoxy compound, a monovalent | monohydric epoxy compound is preferable. The epoxy compound having a valence of 2 or more may undergo a crosslinking reaction with the ethylene-vinyl alcohol copolymer (A) to generate gels, blisters, and the like, thereby reducing the quality of the inner liner. Note that glycidol and epoxypropane are particularly preferable among the monovalent epoxy compounds from the viewpoints of ease of production of the modified ethylene-vinyl alcohol copolymer (B), gas barrier properties, flex resistance, and fatigue resistance. Moreover, it is preferable that the said epoxy compound is made to react 1-50 mass parts with respect to 100 mass parts of ethylene-vinyl alcohol copolymer (A), It is still more preferable to react 2-40 mass parts, It is more preferable to react 35 parts by mass.

  The modified ethylene-vinyl alcohol copolymer (B) has a melt flow rate (MFR) of 190 ° C. and 0.130 g / 10 under a load of 2160 g from the viewpoint of obtaining gas barrier properties, flex resistance and fatigue resistance. Minute, preferably 0.3 to 25 g / 10 minutes, and more preferably 0.5 to 20 g / 10 minutes.

(Viscoelastic body)
The viscoelastic body (C) dispersed in the matrix comprising the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B) has a Young's modulus at 23 ° C. of the ethylene-vinyl alcohol copolymer. It is preferably smaller than the polymer (A) or the modified ethylene-vinyl alcohol copolymer (B), more preferably 500 MPa or less. When the Young's modulus at 23 ° C. of the viscoelastic body (C) is smaller than the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B), the elastic modulus of the resin composition (D) is increased. As a result, the bending resistance of the inner liner can be improved.

  Here, in the present invention, the viscoelastic body (C) includes a multipoint modified viscoelastic body (E) in which a plurality of functional groups that react with a hydroxyl group are introduced into one molecular chain, and a functional group that reacts with a hydroxyl group. It consists of at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G) introduced into the chain by 1 or less. Since ethylene-vinyl alcohol copolymer or modified ethylene-vinyl alcohol copolymer has polarity, a resin having a functional group that reacts with a hydroxyl group is easier to disperse in the matrix, but it consists only of a multi-point modified viscoelastic material. Since the viscoelastic body gels with the ethylene-vinyl alcohol copolymer or the modified ethylene-vinyl alcohol copolymer and the dispersibility may be adversely affected, in the present invention, the multipoint modified viscoelastic body (E) and It is preferable to use a viscoelastic body (C) obtained by blending at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G). Examples of the functional group that reacts with a hydroxyl group include a maleic anhydride group, a hydroxyl group, a carboxyl group, an amino group, an isocyanate group, and an alkoxysilane group.

  As the multipoint modified viscoelastic body (E), a resin having two or more functional groups that react with a hydroxyl group in a molecule, specifically, maleic anhydride-modified hydrogenated styrene-ethylene / butadiene-styrene block copolymer Examples of the polymer include maleic anhydride-modified ultra-low density polyethylene.

［式中、Ｒは炭素数が１〜２０の直鎖または環状の炭化水素基である。］ The partially modified viscoelastic body (F) includes a resin having one functional group that reacts with a hydroxyl group in one molecule, specifically, hydrogenated styrene-ethylene-butadiene-modified at one end with maleic anhydride. Examples thereof include a styrene block copolymer, a terminal-modified styrene-ethylene / butylene-styrene block copolymer (terminal-modified SEBS), a partially-modified styrene-ethylene / butylene-ethylene block copolymer (terminal-modified SEBC), and the like. Further, as partially modified viscoelastic bodies (F), butadiene polymers having an amine, (thio) epoxy, (thio) isocyanate, alkoxysilyl, carboxyl, or silanol functional group or hydroxyl group, styrene -Butadiene copolymer, isoprene polymer, isobutylene-isoprene copolymer, styrene-butadiene-styrene copolymer, styrene-isoprene copolymer, or hydrogenated products thereof (hydrogenated BR, hydrogenated SBR, SEBS, SEPS) , SEBC, etc.). More specifically, it is modified by the method described in “ENDION POLYMERZATION” (HENRY L. HSIEH, Roderic P. QUIRK) in addition to terminal-modified SBR (JSR Technical Review, No. 114/2007) and its hydrogenated product. Examples thereof include modified BR, modified SBR and hydrogenated products thereof. Here, the partially modified viscoelastic body (F) may have a functional group at the end of the molecular chain, or may have a functional group at a portion other than the end. In addition, the following can be used when modifying parts other than the terminal.

[Wherein, R represents a linear or cyclic hydrocarbon group having 1 to 20 carbon atoms. ]

  As the unmodified viscoelastic body (G), a resin having no functional group that reacts with a hydroxyl group, specifically, a hydrogenated styrene-ethylene-butadiene-styrene block copolymer, ultra-low density polyethylene, butadiene rubber ( BR), styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), natural rubber (NR), isoprene rubber (IR), butyl rubber (IIR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), halogenated Butyl rubber (X-IIR), hydrogenated butadiene rubber (hydrogenated BR), hydrogenated styrene butadiene rubber (hydrogenated SBR), hydrogenated isoprene rubber (hydrogenated IR), polystyrene-polyisobutylene-polystyrene block copolymer (SIBS) ) And the like.

  The viscoelastic body (C) is obtained by biaxial extrusion of the multipoint modified viscoelastic body (E) and at least one of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G). It can be prepared by melt-kneading using a machine or a Banbury mixer. In addition, the viscoelastic body (C) comprises the above-described multipoint modified viscoelastic body (E) and at least one of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G), THF, xylene, It can also be prepared by dissolving in a solvent such as toluene or cyclohexane and then removing the solvent by means such as drying. The multipoint modified viscoelastic body (E), the partially modified viscoelastic body (F), and the unmodified viscoelastic body (G) are desirably compatible with each other so as not to cause macrophase separation.

  Here, from the viewpoint of preventing gelation while ensuring sufficient reinforcement by an interfacial reaction between the viscoelastic body (C) and the ethylene-vinyl alcohol copolymer (A) or the modified EVOH (B). The blending amount (F + G / C) of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) in (C) is preferably 20 to 99% by mass and 25 to 95% by mass. More preferably.

  Further, from the viewpoint of promoting the interfacial reaction with the modified EVOH to increase the interface reinforcing effect, the unmodified viscoelastic body (G) with respect to the total of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G). The amount (G / F + G) is preferably 10 to 95% by mass.

  In addition, it is preferable that the content rate of the viscoelastic body (C) in a resin composition (D) is the range of 10-70 mass%. When the content of the viscoelastic body (C) is less than 10% by mass, the effect of improving the bending resistance is small. On the other hand, when it exceeds 70% by mass, the gas barrier property of the inner liner may be lowered.

(Resin composition)
The resin composition (D) is obtained by using an ethylene-vinyl alcohol copolymer (A) or a modified ethylene-vinyl alcohol copolymer (B) and a viscoelastic body (C) using a twin screw extruder, a Banbury mixer, or the like. It can be prepared by kneading. The resin composition (D) is preferably in the form of a film when the inner liner is produced, and the layer made of the resin composition (D) is formed by melt molding, preferably extrusion molding such as T-die method or inflation method. Therefore, it is preferably formed into a film or sheet at a melting temperature of 150 to 270 ° C. and used as an inner liner.

  Here, the layer made of the resin composition (D) is preferably crosslinked. When the layer made of the resin composition (D) is not crosslinked, the inner liner is remarkably deformed and becomes non-uniform in the tire vulcanization process, and the gas barrier properties, flex resistance, and fatigue resistance of the inner liner are deteriorated. There is. Here, as a crosslinking method, a method of irradiating energy rays is preferable. Examples of the energy rays include ionizing radiation such as ultraviolet rays, electron beams, X-rays, α rays, γ rays, and among these, electron beams are used. Particularly preferred. The electron beam irradiation is preferably performed after the resin composition (D) is processed into a molded body such as a film or a sheet. Here, the dose of the electron beam is preferably in the range of 60 Mrad or less, and more preferably in the range of 1 to 50 Mrad. When the electron beam dose is less than 1 Mrad, crosslinking is difficult to proceed. On the other hand, when it exceeds 60 Mrad, the molded body is deteriorated, and the layer made of the resin composition (D) becomes hard and easily cracked.

  The resin composition (D) preferably has a Young's modulus at −20 ° C. of 1500 MPa or less. When the Young's modulus at −20 ° C. is 1500 MPa or less, durability when used in a cold district can be improved.

Furthermore, the layer made of the resin composition (D) preferably has an oxygen transmission rate of 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less at 20 ° C. and 65% RH, 1.0 × 10 ⁻¹² cm ³ · cm ² · sec · cmHg or less is more preferable, and 5.0 × 10 ⁻¹³ cm ³ · cm / cm ² · sec · cmHg or less is even more preferable. preferable. When the oxygen permeation amount at 20 ° C. and 65% RH exceeds 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg, a resin is used to increase the internal pressure retention of the tire when used as an inner liner. The layer made of the composition (D) must be thick, and the weight of the tire cannot be reduced sufficiently.

  Further, the thickness of the layer made of the resin composition (D) is preferably 100 μm or less, more preferably the lower limit is 0.1 μm or more, and further preferably in the range of 1 to 80 μm. More preferably, it is in the range of ˜60 μm. When the thickness of the layer made of the resin composition (D) exceeds 100 μm, when used as an inner liner, the effect of reducing the weight becomes smaller than that of a conventional butyl rubber-based inner liner, and the bending resistance and fatigue resistance are also reduced. It is easy to break and crack due to bending deformation at the time of rolling the tire. In addition, since the cracks are easily extended, the internal pressure retention of the tire may be reduced as compared with that before use. On the other hand, if it is less than 0.1 μm, the gas barrier property is insufficient, and the tire internal pressure retention property may not be sufficiently secured.

  The inner liner for a pneumatic tire of the present invention preferably further comprises one or more auxiliary layers made of an elastomer adjacent to the layer made of the resin composition (D). Here, since the auxiliary layer uses an elastomer, it has high adhesion to the hydroxyl group of the modified ethylene-vinyl alcohol copolymer (B) and is difficult to peel from the layer made of the resin composition (D). Therefore, even if a rupture / crack occurs in the layer made of the resin composition (D), it is difficult for the crack to extend. Therefore, the adverse effect such as a large rupture and crack is suppressed, and the internal pressure retention of the tire is sufficiently maintained. Can do. Further, the inner liner for a pneumatic tire of the present invention has one or more adhesive layers at least at one place between the layer made of the resin composition (D) and the auxiliary layer and between the auxiliary layers adjacent to each other. It can also be provided. Examples of the adhesive used for the adhesive layer include a chlorinated rubber / isocyanate-based adhesive, metal lock and the like.

  The inner liner for a pneumatic tire of the present invention is formed as a laminate when it includes an auxiliary layer and, if necessary, an adhesive layer in addition to the layer made of the resin composition (D). Here, as a method for producing a laminate, for example, a method of laminating a layer composed of the resin composition (D) and another layer by coextrusion, a layer composed of the resin composition (D) and an auxiliary layer A method of bonding using an adhesive layer as needed, and a method of bonding a layer made of the resin composition (D) and an auxiliary layer on a drum using an adhesive layer if necessary, etc. Is mentioned.

Here, the auxiliary layer preferably has an oxygen permeation amount of 3.0 × 10 ⁻⁹ cm ³ · cm / cm ² · sec · cmHg or less at 20 ° C. and 65% RH, and preferably 1.0 × 10 ^−. More preferably, it is ⁹ cm ³ · cm / cm ² · sec · cmHg or less. When the oxygen permeation amount at 20 ° C. and 65% RH is not more than 3.0 × 10 ⁻⁹ cm ³ · cm / cm ² · sec · cmHg, the effect of reinforcing the gas barrier property is sufficiently exerted, and the inner pressure retaining property of the tire is maintained. Can be maintained at a high level.

  And as an elastomer used for an auxiliary | assistant layer, a butyl rubber, halogenated butyl rubber, a diene-type elastomer, and a thermoplastic urethane-type elastomer can be mentioned suitably. Here, from the viewpoint of gas barrier properties, butyl rubber and halogenated butyl rubber are preferable, and halogenated butyl rubber is more preferable. Also, butyl rubber and diene-based elastomers are preferable for suppressing the extension of cracks when cracks occur in the layer made of the resin composition (D). Furthermore, a thermoplastic urethane-based elastomer is preferable in order to suppress the generation and extension of cracks while reducing the thickness of the auxiliary layer. In addition, the auxiliary layer can be laminated, and it is particularly preferable to multilayer the auxiliary layer made of an elastomer having various characteristics. In addition, these elastomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  Specific examples of the diene elastomer include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), and chloroprene. Examples thereof include rubber (CR), and among these, natural rubber and butadiene rubber are preferable. These diene elastomers may be used alone or in combination of two or more.

  The thermoplastic urethane-based elastomer is obtained by a reaction of a polyol, an isocyanate compound, and a short chain diol. A polyol and a short chain diol form a linear polyurethane by an addition reaction with an isocyanate compound. Here, the polyol becomes a flexible part in the thermoplastic urethane elastomer, and the isocyanate compound and the short chain diol become a hard part. Note that the properties of thermoplastic urethane elastomers can be changed over a wide range by changing the type, blending amount, polymerization conditions, and the like of raw materials.

  The total thickness of the auxiliary layers is preferably in the range of 50 to 2000 μm, more preferably in the range of 100 to 1000 μm, and still more preferably in the range of 300 to 800 μm. When the total thickness of the auxiliary layers is less than 50 μm, the reinforcing effect is not sufficiently exerted, and it becomes difficult to suppress adverse effects when the layer made of the resin composition (D) breaks or cracks. The internal pressure retention may not be sufficiently maintained. On the other hand, when the total thickness of the auxiliary layers exceeds 2000 μm, the effect of reducing the weight of the tire is reduced.

  The auxiliary layer preferably has a tensile stress at 300% elongation of 10 MPa or less, more preferably 8 MPa or less, and even more preferably 7 MPa or less. When the tensile stress exceeds 10 MPa, the bending resistance and fatigue resistance may be reduced when the auxiliary layer is used for the inner liner.

<Pneumatic tire>
The pneumatic tire of the present invention is characterized in that the tire inner liner described above is used on the inner surface of the tire inside the carcass.

  Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view of one embodiment of the pneumatic tire of the present invention. The tire shown in FIG. 1 has a pair of bead portions 1, a pair of sidewall portions 2, and a tread portion 3 connected to both sidewall portions 2, and extends in a toroid shape between the pair of bead portions 1. A carcass 4 that reinforces each of these parts 1, 2, and 3, and a belt 5 composed of two belt layers disposed on the outer side in the tire radial direction of the crown part of the carcass 4; An inner liner 6 is disposed on the inner surface of the tire.

  In the illustrated example of the tire, the carcass 4 has a main body portion extending in a toroidal shape between a pair of bead cores 7 embedded in the bead portion 1, and around each bead core 7 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 4 are not limited to this.

  In the illustrated tire, the belt 5 includes two belt layers. However, in the tire of the present invention, the number of belt layers constituting the belt 5 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 5 is configured by being laminated. Further, the tire of the illustrated example includes a belt reinforcing layer 8 disposed so as to cover the entire belt 5 outside the belt 5 in the tire radial direction, but the tire of the present invention includes the belt reinforcing layer 8. The belt reinforcing layer having another structure may be provided. Here, the belt reinforcing layer 8 is usually composed of a rubberized layer of cords arranged substantially parallel to the tire circumferential direction. Furthermore, the pneumatic tire of the present invention can further include a known tire member such as a bead filler or a rim guard as necessary.

  In the illustrated tire, the inner liner 6 has only one layer made of the resin composition (D), but the tire of the present invention improves the bending resistance of the layer made of the resin composition (D). Therefore, it is possible to have one or more auxiliary layers as shown in FIGS.

  2 and 3 are enlarged partial cross-sectional views of another example of the tire of the present invention corresponding to the portion II surrounded by the frame in FIG. 2 replaces the inner liner 6 shown in FIG. 1 with a layer 9 made of the resin composition (D) and two layers disposed adjacent to the layer 9 made of the resin composition (D). Provided with an inner liner 13 comprising an auxiliary layer 10, 11 and an adhesive layer 12 disposed outside the auxiliary layer 11. Further, the tire shown in FIG. 3 includes an inner liner 15 having an auxiliary layer 14 on the outside of the adhesive layer 12 shown in FIG. Here, although the tire shown in FIG.2 and FIG.3 equips the outer side of the auxiliary | assistant layer 11 with one adhesive layer 12, the tire of this invention does not need to have the adhesive layer 12, and other layers. One or more adhesive layers may be provided between the two layers. In the tire of the present invention, the number of auxiliary layers constituting the inner liner is not limited to this.

  Furthermore, in the tire according to the present invention, as shown in FIG. 4, the auxiliary layer has a portion corresponding to a width of at least 30 mm in the region from the belt end to the bead portion (for example, a portion indicated by c in FIG. 4). The total thickness of the auxiliary layers is 0.2 mm or more thicker than the total thickness of the auxiliary layer portions (portions indicated by a in FIG. 4) corresponding to the region where the belt 5 exists. preferable. This is an area from the bead part to the belt end part where the distortion is most severe and the crack is likely to occur. In order to improve the durability of such an area, it is effective to increase the thickness of the auxiliary layer in the specific area. Because it is the target. Further, the portion corresponding to the width of at least 30 mm may be any region indicated by b in FIG.

  The tire of the present invention can be produced by a conventional method by applying the above-described resin composition (D) to the inner liner and, if necessary, an auxiliary layer and an adhesive layer. In the tire of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, an inert gas such as nitrogen, or the like can be used.

  As long as the tire of the present invention includes the inner liner for a tire of the present invention having the above-described configuration, the other structures are not particularly limited, and can take various forms. The tire of the present invention can be suitably applied to passenger car tires, large tires, off-the-road tires, automobile tires, motorcycle tires, aircraft tires, agricultural tires, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail using an Example, this invention is not limited to these Examples at all.

(Synthesis of modified ethylene-vinyl alcohol copolymer)
2 parts by mass of an ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% and a saponification degree of 99.9% (190 ° C., MFR under 2160 g load: 5.5 g / 10 min) and N -8 parts by mass of methyl-2-pyrrolidone was added and heated and stirred at 120 ° C for 2 hours to completely dissolve the ethylene-vinyl alcohol copolymer. To this was added 0.4 part by mass of epoxypropane as an epoxy compound, and then heated at 160 ° C. for 4 hours. After completion of the heating, it was precipitated in 100 parts by mass 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. Furthermore, the obtained modified ethylene-vinyl alcohol copolymer was fined 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 to be pelletized. In addition, as a result of measuring the Young's modulus at 23 degreeC of the obtained modified ethylene-vinyl alcohol copolymer by the following method, it was 1300 MPa.

(Measurement method of Young's modulus)
Using a twin screw extruder manufactured by Toyo Seiki Co., Ltd., a film was formed under the following extrusion conditions to produce a single layer film having a thickness of 20 μm. Next, using this film, a strip-shaped test piece having a width of 15 mm was prepared and left in a temperature-controlled room at 23 ° C. and 50% RH for one week, and then autograph [AG-A500 manufactured by Shimadzu Corporation]. Type] was used to measure an SS curve (stress-strain curve) at 23 ° C. and 50% RH under conditions of a chuck interval of 50 mm and a tensile speed of 50 mm / min, and the Young's modulus from the initial slope of the SS curve. Asked.

Screw: 20 mmφ, full flight cylinder, die temperature setting: C1 / C2 / C3 / die = 200/200/200/200 (° C.)

The ethylene content and saponification degree of the ethylene-vinyl alcohol copolymer were measured by ¹ H-NMR using deuterated dimethyl sulfoxide as a solvent [using “JNM-GX-500 type” manufactured by JEOL Ltd.] This is a value calculated from the spectrum obtained in (1). Also, the melt flow rate (MFR) of the ethylene-vinyl alcohol copolymer was such that a sample was filled into a cylinder having an inner diameter of 9.55 mm and a length of 162 mm of a melt indexer L244 [manufactured by Takara Kogyo Co., Ltd.] After melting, an even load was applied using a plunger having a weight of 2160 g and a diameter of 9.48 mm, and the amount of resin extruded per unit time (g / g) from a 2.1 mm diameter orifice provided in the center of the cylinder. 10 minutes). However, when the melting point of the ethylene-vinyl alcohol copolymer is around 190 ° C. or exceeds 190 ° C., it is measured at a plurality of temperatures above the melting point under a load of 2160 g. Was plotted on the vertical axis, and the value calculated by extrapolating to 190 ° C. was taken as the melt flow rate (MFR).

Example 1
JSR Dynalon 4630P (modified olefin) as partially modified viscoelastic body (F), JSR Dynalon 8630P (modified olefin) as partially modified viscoelastic body (F), and multi-point modified viscoelastic body (E Asahi Kasei Tuftec M1943 (maleic anhydride-modified styrene ethylene butylene styrene copolymer) was kneaded using a Banbury mixer to prepare a viscoelastic body. And the Young's modulus of the viscoelastic body was measured by the same method as modified EVOH. Thereafter, the obtained viscoelastic body and the produced modified ethylene-vinyl alcohol copolymer were kneaded with a twin screw extruder to prepare a resin composition. Here, the modified ethylene-vinyl alcohol copolymer, Dynalon 4630P, Dynalon 8630P, and Tuftec M1943 were mixed so that the mass ratio was 40: 28: 28: 4.
And using the obtained resin composition, the resin film 1 (thickness 50 micrometers) was formed with T-die, MI of the obtained resin composition was measured, and the extrudability was evaluated. Moreover, the melt flow rate (MFR) of the resin composition was measured by the following method. The results are shown in Table 1.
Furthermore, the structure shown in FIG. 1 is obtained by using a resin film 1 irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd. as an inner liner. Then, a pneumatic tire for passenger cars having a size of 195 / 65R15 was produced according to a conventional method. And the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 1.

(Extrudability)
MFR (MI) was measured by the following method, and MI was 0.3 or more, “◯”, and less than 0.1 (what the occurrence of melt fracture can be visually confirmed) was “Δ”.

(Melt flow rate)
Samples were filled into a cylinder with an inner diameter of 9.55 mm and a length of 162 mm of Melt Indexer L244 (Takara Industry Co., Ltd.), melted at 210 ° C., and then using a plunger with a weight of 2160 g and a diameter of 9.48 mm. A load was applied evenly, and the amount was calculated from the amount of resin (g / 10 minutes) extruded per unit time from an orifice having a diameter of 2.1 mm provided in the center of the cylinder. However, when the melting point of the resin composition is around 210 ° C. or exceeds 210 ° C., measurement is performed under a load of 2160 g at a plurality of temperatures equal to or higher than the melting point. The value plotted on the axis and extrapolated to 210 ° C. was taken as the melt flow rate (MFR).

(Oxygen permeability coefficient)
The produced inner liner was conditioned at 20 ° C. and 65% RH for 5 days. In accordance with JIS K7126 (isobaric method) using the MOCON OX-TRAN 2/20 type manufactured by Modern Control Co., Ltd. under the conditions of 20 ° C. and 65% RH using the two inner liners that have been humidity-controlled. The oxygen transmission coefficient was measured and the average value was obtained.

(Internal pressure retention)
The internal pressure retention property is the same as that of the tire produced by pressing the above-prepared tire on a rotating drum corresponding to a speed of 80 km / h at an air pressure of 140 kPa with a load of 6 kmN in an atmosphere of −30 ° C. for 10,000 km. After mounting these tires on a 6JJ × 15 rim, the internal pressure was 240 kPa, the internal pressure after 3 months was measured, and the following formula:
Internal pressure retention = ((240−b) / (240−a)) × 100
[Wherein, a is the internal pressure after 3 months of the test tire, and b is the internal pressure after 3 months of the non-running tire described in Comparative Example 1]. In addition, the value after running in Comparative Example 1 was set to 100, and other values were evaluated as indexes.

(Example 2)
Using the resin composition prepared in Example 1 and thermoplastic polyurethane (TPU) [Kuraray Co., Ltd. Kuramylon 3190], using a two-type three-layer coextrusion apparatus, a resin film under the following coextrusion molding conditions: 2 (TPU layer / resin composition layer / TPU layer, thickness: 20 μm / 20 μm / 20 μm) was prepared, and coextrusion was evaluated at that time.
Furthermore, the resin film 2 was irradiated with an electron beam at 300 kGy using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 1.

Extrusion temperature of each resin: C1 / C2 / C3 / die = 170/170/200/200 ° C.
Extruder specifications for each resin:
Thermoplastic polyurethane: 25mmφ extruder P25-18AC [Osaka Seiki Machine Co., Ltd.]
Resin composition: 20 mmφ extruder lab machine ME type CO-EXT [manufactured by Toyo Seiki Co., Ltd.]
T-die specification: 500mm width, 2 types, 3 layers [Plastic Engineering Laboratory Co., Ltd.]
Cooling roll temperature: 50 ° C
Pickup speed: 4m / min

(Example 3)
Asahi Kasei Corporation Tuftec H1052 (unmodified styrene ethylene butylene styrene copolymer) as unmodified viscoelastic body (G) and Asahi Kasei Tuftec M1943 (maleic anhydride modified styrene as multi-point modified viscoelastic body (E) Ethylene butylene styrene copolymer) was kneaded using a biaxial kneader to prepare a viscoelastic body. And the Young's modulus of the viscoelastic body was measured by the same method as modified EVOH. Thereafter, the obtained viscoelastic body and the produced modified ethylene-vinyl alcohol copolymer were kneaded with a twin screw extruder to prepare a resin composition. Here, the modified ethylene-vinyl alcohol copolymer, Tuftec H1052, and Tuftec M1943 were mixed so that the mass ratio was 40:50:10.
And the resin film 3 (50 micrometers in thickness) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 1.
Furthermore, the resin film 3 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 1.

Example 4
Using a Banbury mixer, IR2200 manufactured by Nippon Zeon Co., Ltd. as an unmodified viscoelastic material and E-NR25 (epoxy modified natural rubber) manufactured by Mu-ang Mai Guthrie Public Company Limited as a multi-point modified viscoelastic material The mixture was kneaded to prepare a viscoelastic body. And the Young's modulus of the viscoelastic body was measured by the same method as modified EVOH. Thereafter, the obtained viscoelastic body and the produced modified ethylene-vinyl alcohol copolymer were kneaded with a twin screw extruder to prepare a resin composition. Here, the modified ethylene-vinyl alcohol copolymer, IR2200, and E-NR25 were mixed so that the mass ratio was 40:50:10.
And the resin film 4 (50 micrometers in thickness) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 1.
Furthermore, the resin film 4 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Curetron EBC200-100 for production” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 1.

(Example 5)
IR2200 manufactured by Nippon Zeon Co., Ltd. as an unmodified viscoelastic material, and modified Liq. IR (LIR403) was kneaded using a Banbury mixer to prepare a viscoelastic body. And the Young's modulus of the viscoelastic body was measured by the same method as modified EVOH. Thereafter, the obtained viscoelastic body and the produced modified ethylene-vinyl alcohol copolymer were kneaded with a twin screw extruder to prepare a resin composition. Here, the modified ethylene-vinyl alcohol copolymer, IR2200, and LIR403 were mixed so that the mass ratio was 40:50:10.
And the resin film 5 (50 micrometers in thickness) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 1.
Further, the resin film 5 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Curetron EBC200-100 for production” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 1.

(Example 6)
JSR BR (BR01) as an unmodified viscoelastic body and Ricon modified Liq. BR (130MA8) was kneaded using a Banbury mixer to prepare a viscoelastic body. And the Young's modulus of the viscoelastic body was measured by the same method as modified EVOH. Thereafter, the obtained viscoelastic body and the produced modified ethylene-vinyl alcohol copolymer were kneaded with a twin screw extruder to prepare a resin composition. Here, modified ethylene-vinyl alcohol copolymer, BR, modified Liq. It mixed so that mass ratio might be 40:50:10 with BR.
And the resin film 6 (50 micrometers in thickness) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 2.
Furthermore, the resin film 6 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 2.

(Example 7)
JSR BR (BR01) as an unmodified viscoelastic body and Daicel Epolide PB2600 (epoxy modified BR) as a multipoint modified viscoelastic body were kneaded using a Banbury mixer to prepare a viscoelastic body. And the Young's modulus of the viscoelastic body was measured by the same method as modified EVOH. Thereafter, the obtained viscoelastic body and the produced modified ethylene-vinyl alcohol copolymer were kneaded with a twin screw extruder to prepare a resin composition. Here, the modified ethylene-vinyl alcohol copolymer, BR, and epolide PB2600 were mixed so that the mass ratio was 40:50:10.
And the resin film 7 (thickness 50 micrometers) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 2.
Furthermore, the resin film 7 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 2.

(Comparative Example 1)
The modified ethylene-vinyl alcohol copolymer produced above was kneaded with Asahi Kasei's Tuftec M1943 (maleic anhydride-modified styrene ethylene butylene styrene copolymer) as a multipoint modified viscoelastic body (E) with a twin screw extruder. A resin composition was prepared. Here, the modified ethylene-vinyl alcohol copolymer and Tuftec M1943 were mixed so that the mass ratio was 40:60.
And the resin film 8 was formed with T-die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. The results are shown in Table 1. In addition, although it tried to measure the melt flow rate (MFR) of a resin composition by the method similar to Example 1, extrusion was difficult and could not be measured.
Furthermore, the resin film 8 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 1.

(Example 8)
Without adjusting the viscoelastic body before kneading with the modified EVOH, JSR Dynalon 4630P (modified olefin) as a partially modified viscoelastic body (F) and JSR manufactured as a partially modified viscoelastic body (F) Dynalon 8630P (modified olefin), Asahi Kasei's Tuftec M1943 (maleic anhydride-modified styrene ethylene butylene styrene copolymer) as the multipoint modified viscoelastic body (E), and the modified ethylene-vinyl alcohol copolymer produced above Were kneaded at the same time to prepare a resin composition.
And the resin film 9 (thickness 50 micrometers) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 2.
Furthermore, the resin film 9 was irradiated with an electron beam at 200 kGy by using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 2.

Example 9
In place of the modified EVOH, an unmodified ethylene-vinyl alcohol copolymer (an ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% and a saponification degree of 99.9%, Young's modulus (23 ° C.): 3500 MPa) was used. A resin composition was prepared in the same manner as Example 1 except for the above.
And the resin film 10 (50 micrometers in thickness) was formed with T die using the obtained resin composition. MI of the obtained resin composition was measured and the extrudability was evaluated. Further, the melt flow rate (MFR) of the resin composition was measured in the same manner as in Example 1. The results are shown in Table 2.
Furthermore, the resin film 10 was irradiated with an electron beam at 200 kGy using an electron beam irradiation apparatus “Curetron EBC200-100 for production” manufactured by Nissin High Voltage Co., Ltd., and used as an inner liner. A pneumatic tire for passenger cars was produced according to a conventional method, and the oxygen permeability coefficient of the inner liner and the internal pressure retention of the tire were evaluated. The results are shown in Table 2.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass 5 Belt 6 Inner liner 7 Bead core 8 Belt reinforcement layer 9 Layer which consists of resin composition (D) 10 Auxiliary layer 11 Auxiliary layer 12 Adhesive layer 13 Inner liner 14 Auxiliary layer 15 Inner liner a Area where the belt 5 exists b Area from the bead portion to the belt end c Example of a portion corresponding to a width of at least 30 mm in the area from the belt end to the bead portion

Claims (8)

The ethylene-vinyl alcohol copolymer (A) or a modified ethylene-vinyl alcohol copolymer (B) obtained by reacting the ethylene-vinyl alcohol copolymer (A) is mixed with the ethylene-vinyl alcohol copolymer. An inner liner comprising at least a layer made of a resin composition (D) in which a viscoelastic body (C) having a lower Young's modulus at 23 ° C. than that of a polymer (A) or a modified ethylene-vinyl alcohol copolymer (B) is dispersed. There,
As the viscoelastic body (C), a multipoint modified viscoelastic body (E) in which a plurality of functional groups that react with hydroxyl groups are introduced, and one or less functional groups that react with hydroxyl groups are introduced in one molecular chain, An inner liner for a pneumatic tire comprising at least one of a partially modified viscoelastic body (F) and an unmodified viscoelastic body (G). The ethylene-vinyl alcohol copolymer (A) or a modified ethylene-vinyl alcohol copolymer (B) obtained by reacting the ethylene-vinyl alcohol copolymer (A) is mixed with the ethylene-vinyl alcohol copolymer. An inner liner comprising at least a layer comprising a resin composition (D) in which a viscoelastic body (C) having a lower Young's modulus at 23 ° C. than that of a polymer (A) or a modified ethylene-vinyl alcohol copolymer (B) is dispersed. A manufacturing method comprising:
A multi-point modified viscoelastic body (E) in which a plurality of functional groups that react with hydroxyl groups are introduced, a partially modified viscoelastic body (F) in which one or less functional groups that react with hydroxyl groups are introduced into one molecular chain, and Blending at least one of the unmodified viscoelastic body (G) to prepare the viscoelastic body (C);
The resin composition (D) is prepared by dispersing the prepared viscoelastic body (C) in a matrix comprising the ethylene-vinyl alcohol copolymer (A) or the modified ethylene-vinyl alcohol copolymer (B). And a process of
Forming a layer comprising the prepared resin composition (D);
The manufacturing method of the inner liner for pneumatic tires characterized by including these.   The total amount of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) in the viscoelastic body (C) is 20 to 99% by mass. The manufacturing method of the inner liner for pneumatic tires of 2.   The amount of the unmodified viscoelastic body (G) in the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) is 10 to 95% by mass. Or the manufacturing method of the inner liner for pneumatic tires of 3.   The viscoelastic body (C) is prepared by melt-kneading the multipoint modified viscoelastic body (E) and at least one of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G). The method for producing an inner liner for a pneumatic tire according to claim 2, wherein the method is performed.   The viscoelastic body (C) is prepared using the multipoint modified viscoelastic body (E) and at least one of the partially modified viscoelastic body (F) and the unmodified viscoelastic body (G) as a solvent. The method for producing an inner liner for a pneumatic tire according to claim 2, wherein the solvent is removed after dissolution and mixing.   The inner liner for pneumatic tires manufactured using the manufacturing method in any one of Claims 2-6.   A pneumatic tire using the inner liner for a pneumatic tire according to claim 1 or 7.

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