JP2019104780A - Rubber composition, inner liner rubber, and tire - Google Patents

Abstract

To provide a rubber composition capable of producing a vulcanized rubber excellent in gas barrier properties and low-temperature durability, and to provide an inner liner rubber and a tire excellent in gas barrier properties and low-temperature durability.SOLUTION: The rubber composition contains a rubber component, a reinforcing filler, and a hydrogenated resin. The rubber component contains 80 mass% or more of a modified or unmodified butyl rubber. The hydrogenated resin has a glass transition temperature of 50°C or higher and lower than 65°C. The content of the hydrogenated resin is 1 pt.mass or more and 20 pts.mass or less based on 100 pts.mass of the rubber component. The rubber composition has a breaking elongation at -40°C of 330% or more as vulcanized rubber characteristics.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition, an inner liner rubber, and a tire.

  In order to maintain the air pressure of the tire for a long time, the inner liner of the tire is required to have air permeation resistance, and is also required to have crack resistance which does not cause cracks (cracks) even under repeated bending deformation. Heretofore, butyl-based rubbers which are excellent in air permeability among various rubbers have been used for the inner liner. On the other hand, functional resin films have been developed in recent years, and many resin films are more excellent in gas barrier properties than butyl rubber.

For example, in Patent Document 1, sufficient dispersibility can be obtained by using butyl-based rubber as a rubber component and combining clay and carbon black having an average aspect ratio of less than 3 to 30 at a specific ratio as a filler thereof. A rubber composition for an inner liner is disclosed, in which low air retention, flex resistance and low temperature property are realized throughout the rubber composition.
Patent Document 2 discloses a rubber composition for an inner liner comprising a blend rubber of a butyl rubber and a diene rubber as a rubber component, and by causing different specific fillers to be unevenly distributed to each rubber, the crack resistance at low temperature and Achieving both air tightness.
Further, Patent Document 3 discloses, as a composition that can be used as a raw material of a tire, an elastomer composition comprising a C4-C7 monoolefin elastomer, a hydrocarbon polymer additive, and a clay, in gas barrier properties. It is shown that it is excellent.

JP 2002-88206 A Japanese Patent Application Laid-Open No. 9-316256 JP, 2010-43257, A

Generally, the inner liner of a tire is required to have both good gas barrier properties and low temperature durability, and the above-mentioned prior art also has a relatively good balance of physical properties. However, in recent years, physical property balance at a higher level has been required, and an inner liner having improved gas barrier properties and low temperature durability more than ever is required.
An object of the present invention is to provide a rubber composition capable of producing a vulcanized rubber excellent in gas barrier properties and low temperature durability, and an inner liner rubber and tire excellent in gas barrier properties and low temperature durability.

<1> A rubber composition comprising a rubber component, a reinforcing filler, and a hydrogenated resin, wherein the rubber component contains 80% by mass or more of modified or unmodified butyl rubber, and the glass of the hydrogenated resin The transition temperature is 50 ° C. or more and less than 65 ° C., the content of the hydrogenated resin is 1 part by mass or more and less than 20 parts by mass with respect to 100 parts by mass of the rubber component, and the fracture at −40 ° C. as a vulcanized rubber characteristic It is a rubber composition whose elongation is 330% or more.

<2> The rubber composition according to <1>, wherein the hydrogenated resin is a hydrogenated dicyclopentadiene resin.
<3> The rubber composition according to <1> or <2>, wherein the reinforcing filler is carbon black.
<4> The rubber composition according to any one of <1> to <3>, in which the content of the reinforcing filler is 15 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

It is an inner liner rubber using the rubber composition as described in any one of <5><1>-<4>.
<6> A tire using the inner liner rubber according to <5>.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can manufacture the vulcanized rubber which is excellent in gas barrier property and low temperature durability, and the inner liner rubber and tire which are excellent in gas barrier property and low temperature durability can be provided.

<Rubber composition>
The rubber composition of the present invention is a rubber composition containing a rubber component, a reinforcing filler, and a hydrogenated resin, wherein the rubber component contains 80% by mass or more of modified or unmodified butyl rubber, The glass transition temperature of the hydrogenated resin is 50 ° C. or more and less than 65 ° C., and the content of the hydrogenated resin is 1 part by mass or more and less than 20 parts by mass with respect to 100 parts by mass of the rubber component. It is a rubber composition whose breaking elongation at -40 ° C is 330% or more.
The rubber composition of the present invention contains a hydrogenated resin having a glass transition temperature of 50 ° C. or more and less than 65 ° C. The hydrogenated resin has a reduced amount of double bonds in the molecular chain as compared to the non-hydrogenated resin, and the reaction with other molecular chains is less likely to occur. Therefore, it is considered that the low temperature durability of a vulcanized rubber such as an inner liner rubber obtained from the rubber composition is improved. Further, the hydrogenated resin used in the rubber composition of the present invention has a good affinity to butyl rubber, and it is considered that the gas barrier properties of the vulcanized rubber obtained from the rubber composition also become good.
Hereinafter, the rubber composition of the present invention will be described in detail.

[Rubber component]
The rubber composition of the present invention contains a rubber component.
The rubber component contained in the rubber composition of the present invention contains 80% by mass or more of modified or unmodified butyl rubber. When the content of the modified or unmodified butyl rubber in the rubber component is less than 80% by mass, the gas barrier properties of the vulcanized rubber obtained from the rubber composition tend to be lowered. The content of the modified or unmodified butyl rubber in the rubber component is preferably 90% by mass or more, more preferably 95% by mass or more, and 100% by mass from the viewpoint of improving the gas barrier properties. It is also good.
Examples of the modified butyl rubber include chlorinated butyl rubber, brominated butyl rubber, and halogenated butyl rubber such as rubber obtained by further modifying the chlorinated butyl rubber and brominated butyl rubber.
Commercially available modified butyl rubber may be used. For example, as chlorinated butyl rubber, "Enjay Butyl HT10-66" manufactured by Enjay Chemical Co., Ltd. may be mentioned, and as brominated butyl rubber, "bromobutyl 2255", "bromobutyl 2222" manufactured by Exxon may be mentioned.
The butyl rubber may be used alone or in combination of two or more.

The rubber component contained in the rubber composition of the present invention may contain rubber other than modified or unmodified butyl rubber. Examples of rubber other than modified or unmodified butyl rubber include diene rubber such as natural rubber (NR) and synthetic diene rubber.
Specific examples of synthetic diene rubbers include polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), butadiene-isoprene copolymer rubber (BIR), and styrene-isoprene copolymer. Polymer rubber (SIR), styrene-butadiene-isoprene copolymer rubber (SBIR), etc. may be mentioned. The diene rubber may be used alone or in combination of two or more.

[Hydrogenated resin]
The rubber composition of the present invention contains a hydrogenated resin having a glass transition temperature of 50 ° C. or more and less than 65 ° C. Thereby, the gas barrier properties and low temperature durability of vulcanized rubber such as inner liner rubber obtained from the rubber composition can be improved. In the present invention, the hydrogenated resin is a resin obtained by hydrogenating double bonds of the resin, and may be a completely hydrogenated resin or a partially hydrogenated resin.

  The hydrogenated resin used in the rubber composition of the present invention is not particularly limited as long as it has a glass transition temperature of 50 ° C. or more and less than 65 ° C., but is preferably a resin obtained by hydrogenating a petroleum resin or a natural resin. Petroleum resins used as raw materials for hydrogenated resins are, for example, decomposed oil residues containing unsaturated hydrocarbons such as olefins and diolefins by-produced together with petrochemical basic materials such as ethylene and propylene by thermal decomposition of naphtha of the petrochemical industry. The mixture is obtained by polymerizing the mixture as it is with a Friedel-Crafts-type catalyst. This petroleum resin is obtained by (co) polymerizing an aliphatic petroleum resin obtained by (co) polymerizing a C5 fraction obtained by pyrolysis of naphtha, and a C9 fraction obtained by pyrolysis of naphtha. Aromatic petroleum resin, copolymerized petroleum resin obtained by copolymerizing the above-mentioned C5 fraction and C9 fraction, dicyclopentadiene system manufactured mainly from high purity dicyclopentadiene obtained by dimerizing cyclopentadiene Alicyclic compound-based petroleum resins such as resins, styrene, substituted styrene, styrene-based resins such as copolymers of styrene and other monomers, and the like can be mentioned.

Moreover, as a natural resin used as the raw material of a hydrogenated resin, terpene resin, such as alpha-pinene type | system | group, (beta) -pinene type | system | group, dipentene type | system | group;
The hydrogenated resin used in the rubber composition of the present invention has a good affinity to butyl rubber, and from the viewpoint of improving the gas barrier properties and low temperature durability of the vulcanized rubber obtained from the rubber composition, a hydrogenated alicyclic compound Preferred are petroleum resins, and among them, hydrogenated dicyclopentadiene resins (hydrogenated DCPD resins) are more preferable. A hydrogenated resin may be used individually by 1 type, and may be used in combination of 2 or more type.

Specifically, examples of the hydrogenated dicyclopentadiene resin include "SU 120", "SU 210", and "SU 400" manufactured by KOLON, and "Oppera PR 140" manufactured by Exxon.
As hydrogenated resin other than hydrogenated dicyclopentadiene type resin, "hydrogenated C9 ARCON P100" of Arakawa Chemical Industries, Ltd., etc. are mentioned.

The glass transition temperature of the hydrogenated resin used for the rubber composition of the present invention is 50 ° C. or more and less than 65 ° C. Outside the range, the low temperature durability of the vulcanized rubber obtained from the rubber composition tends to be deteriorated. The glass transition temperature of the hydrogenated resin is preferably 50 to 62 ° C., and more preferably 50 to 60 ° C., from the viewpoint of making both the low temperature durability and the gas barrier property of the vulcanized rubber excellent.
The glass transition temperature of the resin can be measured by differential scanning calorimetry (DSC) according to JIS K 7121 (2012). In DSC measurement, for example, a temperature (Tg + 30 ° C) higher than the glass transition temperature of the resin at 20 ° C / min after holding for 10 minutes near a temperature (Tg-50 ° C) lower than the glass transition temperature of the resin The temperature should be raised to the vicinity).

The content of the hydrogenated resin in the rubber composition is 1 part by mass or more and less than 20 parts by mass with respect to 100 parts by mass of the rubber component. If the content of the hydrogenated resin is less than 1 part by mass with respect to 100 parts by mass of the rubber component, the gas barrier properties of the vulcanized rubber tend to deteriorate, and if it is 20 parts by mass or more, the low temperature durability of the vulcanized rubber It tends to get worse.
From the viewpoint of improving gas barrier properties and low temperature durability, the content of the hydrogenated resin is preferably 3 parts by mass or more and 18 parts by mass or less, and 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the rubber component. It is more preferable that

[Reinforcing filler]
The rubber composition of the present invention contains a reinforcing filler. Examples of the reinforcing filler include carbon black, silica, alumina, zirconia and the like. From the viewpoint of improving the gas barrier properties and low temperature durability of the vulcanized rubber obtained from the rubber composition, as the reinforcing filler, carbon black or silica is preferable, and carbon black is more preferable. As the reinforcing filler, one kind may be used alone, or two or more kinds may be used in combination.
There is no restriction | limiting in particular as carbon black, For example, SRF, GPF, FEF, HAF, ISAF, SAF etc. can be used.
The silica is not particularly limited, and any commercially available silica can be used, and wet silica, dry silica, colloidal silica and the like can be used.

The content of the reinforcing filler in the rubber composition of the present invention is preferably 15 to 80 parts by mass, and more preferably 20 to 50 parts by mass with respect to 100 parts by mass of the rubber component.
By making the content of the reinforcing filler of the rubber composition within such a range, the gas barrier properties and low temperature durability of vulcanized rubber such as inner liner rubber obtained from the rubber composition are further improved. Can.

[Layered or plate-like mineral]
The rubber composition of the present invention preferably contains a layered or plate-like mineral.
When the rubber composition contains such a mineral, the gas barrier properties of a vulcanized rubber such as an inner liner rubber obtained from the rubber composition can be improved. The aspect ratio of the layered or plate-like mineral is preferably 3 to 30 from the viewpoint of improving the gas barrier properties.
Although the kind in particular of a mineral is not restrict | limited, From a viewpoint of improving gas barrier property, it is preferable that it is an inorganic clay mineral. The inorganic clay mineral may be a natural product or a synthetic product, and examples thereof include kaolin clay, clay, mica, feldspar, silica, and a hydrous composite of alumina, and the like. These may be used alone or in combination of two or more.
Among these, kaolinic clay and sericitic clay are preferable from the viewpoint of gas barrier properties.
It is preferable that it is 10-50 mass parts with respect to 100 mass parts of rubber components, and, as for content of the said mineral of a rubber composition, it is more preferable that it is 20-40 mass parts.

[Vulcanizing agent]
The rubber composition of the present invention preferably contains a vulcanizing agent.
The vulcanizing agent is not particularly limited, and usually, sulfur is used, and for example, powder sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur and the like can be mentioned.
The content of the vulcanizing agent is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. When the content is 0.1 parts by mass or more, vulcanization can be sufficiently advanced, and when the content is 10 parts by mass or less, aging resistance of vulcanized rubber such as inner liner rubber is suppressed. be able to.
The content of the vulcanizing agent in the rubber composition is more preferably 0.2 to 5 parts by mass and still more preferably 0.4 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

[Vulcanization accelerator]
The rubber composition also preferably contains a vulcanization accelerator in order to accelerate the vulcanization of the rubber component.
Examples of vulcanization accelerators include sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, xanthogenate-based vulcanization accelerators, thiuram-based vulcanization accelerators, and the like. Be These vulcanization accelerators may be used alone or in combination of two or more.
The content of the vulcanization accelerator in the rubber composition is preferably 0.1 to 10 parts by mass and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

  The rubber composition of the present invention may contain, in addition to the above-mentioned components, compounding agents which are blended and used in a usual rubber composition. For example, silane coupling agents, vulcanization accelerators, vulcanization retarders, softeners such as various process oils, zinc flower, stearic acid, waxes, anti-aging agents, compatibilizers, workability improvers, lubricants, Commonly used various compounding agents such as tackifiers, UV absorbers, dispersants, homogenizing agents and the like can be mentioned.

  When the rubber composition is obtained, there is no particular limitation on the method of blending the above components, and all the component materials may be blended at one time and kneaded, or the components may be blended in two or three stages. Kneading may be performed. In addition, kneaders, such as a roll, an internal mixer, and a Banbury rotor, can be used in the case of kneading | mixing. Further, when forming into a sheet shape, a band shape or the like, a known forming machine such as an extrusion molding machine or a press machine may be used.

[Vulcanized rubber properties]
The vulcanized rubber of the rubber composition obtained as described above is excellent in low-temperature durability, and specifically, has vulcanized rubber properties such that the elongation at break at −40 ° C. is 330% or more. Therefore, the rubber composition of the present invention is suitable for a tire rubber member which is subjected to repeated bending deformation such as inner liner rubber, sidewall rubber and the like. The breaking elongation of the vulcanized rubber of the rubber composition is preferably 350% or more, more preferably 370% or more.
In addition, the elongation at break (Eb; Elongation at break) of a vulcanized rubber can be measured by the method as described in an Example.

The vulcanized rubber of the rubber composition of the present invention has a stress at 50% elongation in a stress-strain curve measured at -40 ° C. by a tensile tester, at 100% elongation at which the stress at 50% elongation is measured under the same conditions. Preferably, it is greater than the stress. When the vulcanized rubber of the rubber composition satisfies the above requirements, the gas barrier properties and the low temperature durability can be improved.
The (stress at 35% elongation) / (stress at 75% elongation) of the vulcanized rubber of the rubber composition of the present invention is preferably 1.2 or more, more preferably 1.25 or more More preferably, it is 1.3 or more. Further, (stress at 35% elongation)-(stress at 75% elongation) is preferably 1.5 MPa or more, more preferably 1.9 MPa or more, and further preferably 4.0 MPa or more preferable.
The stress at 35% elongation and the stress at 75% elongation can be controlled by appropriately adjusting the type, amount, etc. of the hydrogenated resin.
The stress-strain curve of the vulcanized rubber can be obtained by the method described in the examples.

<Inner liner rubber, tire>
The tire of the present invention is manufactured by the usual method using the rubber composition of the present invention at the inner liner portion. That is, the rubber composition of the present invention obtained by blending the various components as described above is processed as an inner liner member in an unvulcanized state, and the inner liner rubber of the tire is manufactured by the conventional manufacturing process. As molding and processing. The inner liner rubber can be formed as a laminate of an inner liner layer and a carcass adjacent layer (laminate for an inner liner), and the rubber composition of the present invention is suitable as an inner liner rubber constituting the inner liner layer is there. Vulcanization of the inner liner layer is carried out at a vulcanization temperature of 130 ° C. or more after being molded into a tire.
The method of manufacturing a tire according to the present invention includes the steps of: laminating a different tire member on the laminate for an inner liner of the tire; and molding the green tire, and vulcanizing the green tire. Is preferred.
The inner liner rubber of the present invention has excellent gas barrier properties and low temperature durability, so the thickness of the inner liner layer can be made thinner than in the prior art.

<Examples 1 to 4, Comparative Examples 1 to 6, Reference Examples 1 to 3>
[Preparation of rubber composition]
Each component was kneaded according to the composition shown in the following Tables 1 and 2 to prepare a rubber composition.
The details of each component shown in Tables 1 and 2 are as follows.

(1) Rubber component Brominated butyl rubber: Exxon company, "bromobutyl 2255"
(2) Reinforcing filler Filler (CB): carbon black, manufactured by CABOT, “STERLING V” company [nitrogen adsorption specific surface area (N ₂ SA) = 30 m ² / g]

(3) Minerals: clay, manufactured by BASF, "ASP NC X-1"
(4) Oil: Made by JX, "Super oil Y22"
(5) Stearic acid: manufactured by NOF Corporation, "Sealed stearic acid"
(6) Zinc flower: manufactured by Hakusui Tech, "Zinc flower"
(7) Vulcanization accelerator: di-2-benzothiazolyl disulfide, manufactured by UNYROYAL, "NAUGEX MBTS"
(8) Sulfur: "HK200-5" manufactured by Tsurumi Chemical Co., Ltd.

(9) Resin DCPD resin 1: manufactured by JXTG Energy Co., Ltd., "Niseki Neo Resin B-140" (Tg = 72 ° C)
DCPD resin 2: Nippon Zeon Co., Ltd. “Quintone 1920” (Tg = 65 ° C.)
Hydrogenated DCPD resin 1: manufactured by KOLON "SU 120" (Tg = 64 ° C)
Hydrogenated DCPD resin 2: manufactured by KOLON "SU100S" (Tg = 49.8 ° C)
Hydrogenated DCPD resin 3: manufactured by KOLON "SU210" (Tg = 58.6 ° C)
Hydrogenated DCPD resin 4: manufactured by KOLON "SU 400" (Tg = 51.3 ° C)
Hydrogenated DCPD resin 5: manufactured by KOLON "SU 430" (Tg = 75.6 ° C)

[Manufacture of tire]
It was set as the rubber composition for inner liners using each rubber composition of an Example and a comparative example.
The rubber composition for the inner liner is wound on a molding drum, the carcass is pasted thereon, further, other tire members are pasted, a green tire is molded, and the green tire is vulcanized, Size: A LSR 195 / 85R16 pneumatic tire was produced.

[Evaluation]
The gas barrier properties and low temperature durability of the vulcanized rubber and the tire were evaluated as follows.
The low temperature durability was evaluated by conducting the elongation at break of the vulcanized rubber at -40 ° C and the low temperature drum test of the tire. Furthermore, low temperature stress-strain characteristics of the vulcanized rubber were also evaluated.
The vulcanized rubber test pieces used for the evaluation of the gas barrier properties and the elongation at break were obtained by calendering each rubber composition of Examples and Comparative Examples under the conditions of 145 ° C. and 45 minutes. Obtained by vulcanization. The thickness of the vulcanized rubber test piece was 1 mm.

1. Stress at low temperature (evaluation of strain characteristics) and elongation at break: A sheet of 2 mm-thick vulcanized rubber is processed into a ring and cooled to -40 ° C, and a sample is pulled at a speed of 100 mm / min at -40 ° C. The stress until failure was measured to obtain a stress-strain curve. The stress at 35% elongation and the stress at 75% elongation were determined from the obtained stress-strain curve. In the case where the sample is broken immediately after the sample is pulled, for example, the sample is broken before reaching 35% elongation and before reaching 75% elongation, the evaluation result column is indicated as "-".
Furthermore, the elongation at break was determined. Elongation at break was obtained by measuring the length of the sample when the sample broke and as a length relative to the length before pulling (100%).

2. Gas barrier property The air permeation ratio of the vulcanized rubber test piece was measured at 60 ° C. using an air permeation tester M-C1 (manufactured by Toyo Seiki Co., Ltd.). Assuming that the air permeability of Reference Example 1 is 100, the air permeability (JIS K 6275-1 (2009)) is indicated by an index. The smaller the index, the smaller the air permeability, and the better the gas barrier properties.

3. Low temperature drum test The internal pressure at room temperature of the tire manufactured as described above was 550 kPa, and it was made to travel 1,000 km by pressing with a load of 1120 kgf on a rotating drum corresponding to a speed of 50 km / h in an atmosphere of -45 ° C. . The appearance of the inner liner of the tire after running on a drum was visually observed to evaluate the presence or absence of a crack.

  From Tables 1 and 2, the rubber compositions of Comparative Examples 1, 3 and 6 using a non-hydrogenated resin; Comparative Examples 2 and 5 using a hydrogenated resin having a glass transition temperature not higher than 50 ° C and lower than 65 ° C. Rubber composition; and the rubber composition of Comparative Example 4 having a content exceeding 20 parts by mass with respect to 100 parts by mass of the rubber component, even if a hydrogenated resin whose glass transition temperature is not 50 ° C. or more and less than 65 ° C. is used It was confirmed that the obtained vulcanized rubber had a breaking elongation of less than 330% and a small breaking elongation. Moreover, as for the tire obtained from the rubber composition of Comparative Examples 1-6, the crack was confirmed after the low temperature drum test. From the above results, it was found that the vulcanized rubber and tire obtained from the rubber compositions of Comparative Examples 1 to 6 were inferior in low temperature durability.

  The vulcanized rubber and tire obtained from the rubber compositions of Reference Examples 1 to 3 which do not contain a resin have a gas barrier index of more than 80, and no gas barrier property is obtained or cracks are confirmed after a low temperature drum test. It was found that it was difficult to make both the gas barrier property and the low temperature durability both excellent in the rubber compositions of Reference Examples 1 to 3.

  On the other hand, the vulcanized rubber and tire obtained from the rubber composition of the example containing 1 to 20 parts by mass of a hydrogenated resin having a glass transition temperature of 50 ° C. or more and less than 65 ° C. have a gas barrier index of 80 or less And while the breaking elongation exceeded 330%, the crack was not confirmed after the low temperature drum test, and it turned out that it is excellent in both gas barrier property and low temperature endurance.

Claims (6)

Rubber component,
Reinforcing filler,
A rubber composition containing a hydrogenated resin,
The rubber component contains 80% by mass or more of modified or unmodified butyl rubber,
The glass transition temperature of the hydrogenated resin is 50 ° C. or more and less than 65 ° C.,
The content of the hydrogenated resin is 1 part by mass or more and less than 20 parts by mass with respect to 100 parts by mass of the rubber component,
The rubber composition whose breaking elongation at -40 degreeC is 330% or more as a vulcanized rubber characteristic.   The rubber composition according to claim 1, wherein the hydrogenated resin is a hydrogenated dicyclopentadiene resin.   The rubber composition according to claim 1, wherein the reinforcing filler is carbon black.   The rubber composition according to any one of claims 1 to 3, wherein the content of the reinforcing filler is 15 to 80 parts by mass with respect to 100 parts by mass of the rubber component.   An inner liner rubber using the rubber composition according to any one of claims 1 to 4.   A tire using the inner liner rubber according to claim 5.