JP2009001680A - Rubber composition for breaker and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for breakers, which can reduce the usage of raw materials originated from petroleum resources and simultaneously enables both the maintenance of characteristics and the improvement of processability required for rubber compositions for breakers, such as durability and steel adhesiveness, and to provide a pneumatic tire having a breaker using the rubber composition and having improved travel safety. <P>SOLUTION: This rubber composition for the breakers comprises a rubber component, and 20 to 60 pts.mass of silica and 0.5 to 15 pts.mass of at least one of a terpene-based resin and a rosin-based resin relative to 100 pts.mass of the rubber composition, wherein the rubber component contains 30 to 100 mass% of a natural rubber component comprising at least one of natural rubber and a modified natural rubber, and the pneumatic tire has a breaker using the rubber composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition for a breaker and a pneumatic tire provided with a breaker using the rubber composition.

  In recent years, methods for reducing the amount of raw materials derived from petroleum resources have been studied in various technical fields due to increasing interest in environmental problems. Currently, commercially available tires are composed of raw materials in which more than half of the total weight is petroleum resources. For example, a general tire for a passenger car contains about 20% by mass of synthetic rubber, about 20% by mass of carbon black, a softener, a synthetic fiber, and the like, so that about 50% by mass or more of the entire tire is derived from raw materials of petroleum resources. It is configured. The rubber composition for tires is mixed with a tackifier for the purpose of improving the tackiness and improving the workability by reducing the viscosity. As the tackifier, a C5 resin, a C9 series can be used. Resins derived from petroleum resources such as resins and phenolic resins are generally used. Accordingly, it is desired to develop a rubber for tires using a raw material derived from a natural resource that satisfies the same or more required characteristics as when using a raw material derived from a petroleum resource.

  Here, 100 to 150 parts by weight of a terpene resin is blended with 100 parts by weight of a diene rubber for the purpose of providing a tread rubber composition that satisfies industrial workability and has excellent grip properties. A tread rubber composition is known. In addition, it contains 50 parts by weight or more of natural rubber or polyisoprene rubber among diene rubber components, and contains 1 to 50 parts by weight of a terpene resin having a specific kinematic viscosity. There is also known a technique capable of providing a rubber composition for a tire with a small amount of addition. Further, for the same purpose, a phenol-modified terpene having a specific softening point, hydroxyl value and kinematic viscosity, including a reinforcing filler containing 50 parts by weight or more of natural rubber and 60% by weight or more of silica among diene rubber components. A rubber composition for a tire tread obtained by blending 0.5 to 15 parts by weight of a resin is also known. However, these rubber compositions contain a large amount of natural resource materials without blending petroleum-based resins, and reduce the burden on the environment, but the rubber compositions for breakers and the performance required for them Is not considered at all, and the workability is not sufficient.

  JP-A-11-11106 (Patent Document 1) describes that 1 to 10 parts by weight of a tackifier is added to 100 parts by weight of a rubber component comprising a diene rubber and a bromide of an isobutylene / p-methylstyrene copolymer. A tubeless tire without an inner liner using a rubber composition for containing a case cord covering rubber layer is disclosed, and examples of the tackifier include terpene resins and rosin derivatives. According to Patent Document 1, it is described that the adhesiveness with other tire members is excellent by using such a rubber composition.

  JP 2004-2584 A (Patent Document 2) discloses a rubber composition for a tire in which 40 to 500 parts by weight of a filler and 15 parts by weight or more of a resin are blended with 100 parts by weight of a rubber component. Examples of the resin include terpene resins and rosin resins. According to Patent Document 2, it is described that, by using such a composition, both wet grip performance and wear resistance can be achieved using the tread portion.

  Furthermore, Japanese Patent Application Laid-Open No. 2006-63093 (Patent Document 3) discloses a resin and white filler of 8 parts by weight or more with respect to 100 parts by weight of a rubber component containing 80% by weight or more of natural rubber and / or epoxidized natural rubber. A rubber composition for a tread containing a filler composed of 80% by weight or more is disclosed, and examples of the resin include terpene resins, aromatic modified terpene resins, and rosin resins. According to Patent Document 3, it is disclosed that the content of non-petroleum resources can be increased and the conventional performance can be maintained equally.

However, none of the inventions disclosed in Patent Documents 1 to 3 considers the breaker rubber composition and the performance required for it, and it is difficult to say that the processability is sufficient.
Japanese Patent Laid-Open No. 11-11106 JP 2004-2584 A JP 2006-63093 A

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to provide a rubber for a breaker such as durability and steel adhesion while reducing the amount of a raw material derived from petroleum resources. It is to provide a rubber composition for a breaker capable of maintaining both desired properties of the composition and improving processability, and a pneumatic tire having improved running safety by including a breaker using the rubber composition. .

  The rubber composition for a breaker of the present invention comprises at least one of a rubber component, 20 to 60 parts by mass of silica, 0.5 to 15 parts by mass of a terpene resin and a rosin resin with respect to 100 parts by mass of the rubber component. The rubber component contains any one of natural rubber components consisting of at least one of natural rubber and modified natural rubber within a range of 30 to 100% by mass.

  The modified natural rubber used in the rubber composition for a breaker of the present invention is preferably an epoxidized natural rubber.

  The rubber component in the rubber composition for a breaker of the present invention is preferably composed of a natural rubber component.

  The present invention further provides a pneumatic tire provided with a breaker composed of the rubber composition of the present invention described above and a tire cord embedded in the rubber composition.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the usage-amount of the raw material derived from petroleum resources, the maintenance of the characteristic desired for the rubber composition for circuit breakers, such as durability and steel adhesiveness, and improvement of workability are possible. By providing a rubber composition for a breaker and a breaker using the same, a pneumatic tire with improved running safety can be provided.

  The rubber composition for a breaker of the present invention comprises at least one of a rubber component, 20 to 60 parts by mass of silica, 0.5 to 15 parts by mass of a terpene resin and a rosin resin with respect to 100 parts by mass of the rubber component. Contains either. The rubber component used in the present invention is a natural rubber component (hereinafter also simply referred to as “natural rubber component”) composed of at least one of natural rubber (NR) and modified natural rubber within a range of 30 to 100% by mass. Contains.

<Rubber component>
In the rubber composition for a breaker of the present invention, the rubber component contains a natural rubber component composed of at least one of natural rubber and modified natural rubber (ENR). That is, the natural rubber component in the present invention may be composed only of natural rubber, may be composed only of modified natural rubber, or may include both.

  The natural rubber used in the present invention includes any rubber as long as it is known as natural rubber, and the place of origin is not limited. Such natural rubber mainly contains cis 1,4 polyisoprene, but can also contain trans 1,4 polyisoprene according to required characteristics. Therefore, the natural rubber includes natural rubber mainly containing trans 1,4 isoprene, such as balata, which is a kind of rubber from the South American Acatecaceae family, in addition to natural rubber mainly containing cis 1,4 polyisoprene. It is. The natural rubber component in the present invention may contain one or more of such natural rubbers (that is, one component or two or more components). As such natural rubber, for example, natural rubber of grades such as RSS # 3 and TSR can be suitably used.

  The modified natural rubber used in the present invention refers to a product obtained by modifying or purifying the above-described natural rubber, and examples thereof include epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), and hydrogenated natural rubber. The natural rubber component in the present invention may contain one or more of such modified natural rubbers. Among the above, the natural rubber component in the present invention preferably contains epoxidized natural rubber as the modified natural rubber.

  Epoxidized natural rubber is a kind of modified natural rubber in which unsaturated double bonds of natural rubber are epoxidized, and molecular cohesion is increased by epoxy groups that are polar groups. Therefore, the glass transition temperature (Tg) is higher than that of natural rubber, and the mechanical strength, wear resistance, and air permeation resistance are excellent. Examples of such epoxidized natural rubber include commercially available products such as ENR25 (manufactured by Clamp-Lance Gully) (epoxidation rate: 25%), ENR 50 (made by Clamp-Lance Gully) (epoxidation rate: 50%), and the like. You may use what was used and what epoxidized natural rubber may be used. The method for epoxidizing natural rubber is not particularly limited, and examples thereof include a chlorohydrin method, a direct oxidation method, a hydrogen peroxide method, an alkyl hydroperoxide method, and a peracid method. Examples of the peracid method include a method of reacting an organic peracid such as peracetic acid or performic acid as an epoxidizing agent with an emulsion of natural rubber.

  The epoxidation rate of the epoxidized natural rubber (ENR) is preferably 10 mol% or more, and more preferably 25 mol% or more. Here, the epoxidation rate is the ratio of the number of epoxidized to the total number of double bonds in natural rubber before epoxidation ((number of epoxidized double bonds) / (two before epoxidation). The number of double bonds)), and is determined by titration analysis, nuclear magnetic resonance (NMR) analysis, or the like. When the epoxidation rate of the epoxidized natural rubber (ENR) is less than 10 mol%, the processability tends to be low because the glass transition temperature of the epoxidized natural rubber (ENR) is low. The epoxidation rate of the epoxidized natural rubber (ENR) is preferably 70 mol% or less, and more preferably 50 mol% or less. When the epoxidation rate of the epoxidized natural rubber (ENR) exceeds 70 mol%, the hardness is excessively increased, and the desired characteristics such as fatigue resistance in a pneumatic tire including a breaker using the breaker rubber composition Tends to be difficult to obtain.

  More typical examples of the epoxidized natural rubber (ENR) include an epoxidized natural rubber having an epoxidation rate of 25 mol% and an epoxidized natural rubber having an epoxidation rate of 50 mol%.

  In the present invention, the content of the natural rubber component in the rubber component is preferably 30% by mass or more. This is because if the content of the natural rubber component in the rubber component is less than 30% by mass, the effect of reducing the amount of raw material derived from petroleum resources tends to be insufficient. The content of the natural rubber component in the rubber component is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the natural rubber component in the rubber component is preferably 100% by mass (that is, the rubber component is made of a natural rubber component) in that the effect of reducing the amount of raw material derived from petroleum resources is good. For example, the content of the natural rubber component in the rubber component may be 90% by mass or less, further 70% by mass or less, and rubber other than the natural rubber component may be blended as the balance in the rubber component.

  Further, the rubber component may contain a petroleum resource-derived rubber as long as the effects of the present invention are not impaired. Examples of rubbers derived from petroleum resources include styrene butadiene rubber (SBR), butadiene rubber (BR), styrene isoprene copolymer rubber, isoprene rubber (IR), butyl rubber (IIR), chloroprene rubber (CR), and acrylonitrile butadiene rubber. Examples thereof include (NBR), halogenated butyl rubber (X-IIR), and halides of copolymers of isobutylene and p-methylstyrene. Among these, SBR, BR, and IR are preferable because a pneumatic tire including a breaker using the breaker rubber composition can impart desired characteristics such as heat generation.

  When the rubber component contains natural rubber, the content of the natural rubber in the rubber component is preferably 70% by mass or more, and more preferably 90% by mass or more. When the content of the natural rubber in the rubber component is less than 70% by mass, the mechanical strength of the breaker rubber composition tends to be low. In the present invention, the rubber component may consist only of natural rubber.

  When the rubber component contains epoxidized natural rubber as the modified natural rubber, the content of the epoxidized natural rubber in the rubber component is preferably 5% by mass or more, and more preferably 10% by mass or more. When the content of the epoxidized natural rubber in the rubber component is less than 5% by mass, the effect of improving the wear resistance tends to be low. Moreover, it is preferable that the content rate of the epoxidized natural rubber in a rubber component is 50 mass% or less, and it is more preferable that it is 30 mass% or less. When the content of the epoxidized natural rubber in the rubber component exceeds 50% by mass, the rubber hardness tends to be too high, so that the mechanical strength of the breaker rubber composition tends to be low.

  When rubber containing both natural rubber and epoxidized natural rubber is used as the rubber component, the mass ratio of natural rubber to epoxidized natural rubber (mass of natural rubber / mass of epoxidized natural rubber) is It is preferably 5 or more, more preferably 10 or more, and further preferably 15 or more. When the above mass ratio (mass of natural rubber / mass of epoxidized natural rubber) is 5 or more, particularly 10 or more, and further 15 or more, the fatigue resistance is improved in this order. The trend becomes larger.

  When a rubber containing both natural rubber and epoxidized natural rubber is used as the rubber component, the above mass ratio (mass of natural rubber / mass of epoxidized natural rubber) may be 100 or less. Preferably, it is 30 or less, more preferably 20 or less. When the above mass ratio (mass of natural rubber / mass of epoxidized natural rubber) is 100 or less, particularly 30 or less, and further 30 or less, the workability tends to improve in this order. Becomes larger.

  When the rubber component contains deproteinized natural rubber as the modified natural rubber, the content of the deproteinized natural rubber in the rubber component is preferably 10% by mass or more, and more preferably 30% by mass or more. . When the content of the deproteinized natural rubber in the rubber component is less than 10% by mass, the water-resistant adhesion tends to decrease. The content of the deproteinized natural rubber in the rubber component is preferably 70% by mass or less, and more preferably 50% by mass or less. If the content of the deproteinized natural rubber in the rubber component exceeds 70% by mass, the cost tends to increase.

<Silica>
The rubber composition for a breaker of the present invention contains silica in addition to the rubber component described above. Silica functions as a reinforcing filler. By adding silica, the tensile strength of the breaker rubber composition can be improved. In addition, since silica is derived from non-petroleum resources, the amount of raw material derived from petroleum resources in the rubber composition is reduced compared to the case where a reinforcing agent derived from petroleum resources such as carbon black is blended as a main reinforcing agent. Can be reduced.

  The rubber composition for a breaker of the present invention contains 20 to 60 parts by mass of silica with respect to 100 parts by mass of the rubber component described above. When the silica content is less than 20 parts by mass with respect to 100 parts by mass of the rubber component, no improvement in tensile strength can be expected, and when the silica content exceeds 60 parts by mass with respect to 100 parts by mass of the rubber component This is because the fatigue resistance is reduced. The content of silica is preferably within a range of 20 to 60 parts by mass, and more preferably within a range of 30 to 50 parts by mass with respect to 100 parts by mass of the rubber component.

In the breaker rubber composition of the present invention, it is preferable that a BET specific surface area used 50 m ² / g or more silica, BET specific surface area is more preferably used 100 m ² / g or more silica. This is because when a silica having a BET specific surface area of less than 50 m ² / g is used, a breaker having sufficient hardness tends not to be obtained. Further, BET specific surface area of silica is preferably 250 meters ² / g or less, and more preferably less 210 m ² / g. This is because when silica having a BET specific surface area of more than 250 m ² / g is used, the processability of rubber tends to decrease. In addition, the BET specific surface area of the silica mentioned above can be measured by the method based on ASTM-D-4820-93, for example.

Silica may be prepared by a wet method or may be prepared by a dry method. Moreover, as a preferable commercial item, Ultrasil VN2 (made by Degussa) (BET specific surface area: 125 m < ² > / g), Ultrazil VN3 (made by Degussa) (BET specific surface area: 210 m < ² > / g) etc. can be illustrated, for example.

<Terpene resin, rosin resin>
The rubber composition for a breaker of the present invention contains at least one of a terpene resin and a rosin resin. Among these, it is particularly preferable to contain a terpene resin. In addition, you may contain multiple types of terpene resin and rosin resin.

Here, the term “terpene-based resin” as used herein refers to a resin that is polymerized with a terpene compound contained in a plant essential oil generally obtained from plant leaves, trees, roots and the like as a main monomer. The terpene compound is generally a polymer of isoprene (C ₅ H ₈ ), and terpenes classified into monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂ ), etc. A compound having a basic skeleton, such as α-pinene, β-pinene, dipentene, limonene, myrcene, allocymene, ocimene, α-ferrandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1, Examples include 4-cineole, α-terpineol, β-terpineol, γ-terpineol, camphene, tricyclene, sabinene, paramentadienes, and carenes.

  The terpene resin in the present invention includes, as a raw material, terpene compounds other than terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, β-pinene / limonene resin. And an aromatic modified terpene resin using terpene compound and aromatic compound, terpene phenol resin using terpene compound and phenol compound as raw materials, and hydrogenated terpene resin obtained by hydrogenating terpene resin. Here, as an aromatic compound used as the raw material of the aromatic terpene resin in the present invention, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene and the like can be mentioned, and a phenolic compound used as a raw material for the terpene phenol resin. Examples thereof include phenol, bisphenol A, cresol, and xylenol.

  As such a terpene resin, commercially available products such as PX300N (manufactured by Yasuhara Chemical Co., Ltd.) can be suitably used.

  In addition, the “rosin resin” in the present specification is a resin acid such as abietic acid, neoabietic acid, parastrinic acid, levopimaric acid, pimaric acid, isopimaric acid, and dehydroabietic acid obtained by processing pine resin. In addition to natural rosin resin (polymerized rosin) such as gum rosin, wood rosin, tall oil rosin, etc., hydrogenated rosin resin, maleic acid modified rosin resin, modified rosin resin such as rosin modified phenolic resin, rosin glycerin ester Rosin esters such as, disproportionated rosin resins obtained by disproportionating rosin resins, and the like are also included.

  As such a rosin resin, for example, a commercially available product such as tall oil rosin TP90B (manufactured by Harima Chemicals Co., Ltd.) can be suitably used.

  The rubber composition for a breaker of the present invention contains 0.5 to 15 parts by mass of at least one of the above-described terpene resin and rosin resin (particularly terpene resin) with respect to 100 parts by mass of the rubber component. To do. When the content of at least one of the terpene resin and the rosin resin is less than 0.5 parts by mass with respect to 100 parts by mass of the rubber component, no improvement in workability is observed. This is because, when the content of at least one of the resin and the rosin resin exceeds 15 parts by mass with respect to 100 parts by mass of the rubber component, the fracture physical properties are lowered. The rubber composition for a breaker of the present invention preferably contains 0.5 to 15 parts by mass of at least one of the above-mentioned terpene resin and rosin resin with respect to 100 parts by mass of the rubber component, and 1 to 5 parts by mass. It is more preferable to contain part.

<Silane coupling agent>
The rubber composition for a breaker of the present invention contains silica as described above, and it is preferable to blend a silane coupling agent together with this silica. As the silane coupling agent, a conventionally known silane coupling agent can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4- Triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxy Silylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) ) Resulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3 -Trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxy Ethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthio Rubamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc. Sulfide type; mercapto type such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyltriethoxysilane, vinyltrimethoxysilane, etc. Vinyl-based; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxy Amino series such as silane, 3- (2-aminoethyl) aminopropyltrimethoxysilane; γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane , Glycidoxy type such as γ-glycidoxypropylmethyldimethoxysilane; nitro type such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane; 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane , Chloro-based compounds such as 2-chloroethyltrimethoxysilane and 2-chloroethyltriethoxysilane; These silane coupling agents may be used alone or in combination of two or more.

  Among the above, Si69 (made by Degussa) (bis (3-triethoxysilylpropyl) tetrasulfide), Si266 (made by Degussa) (bis (3-triethoxysilylpropyl) disulfide because of good processability Etc.) are preferably used.

  When the silane coupling agent is further contained, the content is not particularly limited, but is preferably 10 parts by mass or more with respect to 100 parts by mass of silica.

<Carbon black>
The rubber composition for a breaker of the present invention preferably further contains carbon black as a reinforcing agent as long as the effects of the present invention are not impaired. By blending carbon black, good mechanical strength is imparted to the rubber composition for breakers. However, since carbon black is generally derived from petroleum resources, in order to reduce the amount of raw materials derived from petroleum resources, The blending amount of carbon black is preferably 5 parts by mass or less, further 3 parts by mass or less, and further 1 part by mass or less with respect to 100 parts by mass of the rubber component. On the other hand, it is preferable that the blending amount of the carbon black is 10 parts by mass or more with respect to 100 parts by mass of the rubber component in that the effect of improving the mechanical strength by blending the carbon black is favorable. More preferably.

  As a preferable commercial product of carbon black, for example, Show Black N220 (manufactured by Cabonet Japan Co., Ltd.) can be exemplified.

<Other ingredients>
In addition to the above-described components, the rubber composition for breakers of the present invention includes other compounding agents conventionally used in the rubber industry, such as vulcanizing agents, stearic acid, vulcanization accelerators, vulcanization accelerators, oils. Curing resin, wax, anti-aging agent, etc. may be blended.

  As the vulcanizing agent, an organic peroxide or a sulfur-based vulcanizing agent can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, and di-t-butyl peroxide. , T-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoyl) Peroxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 or 1,3-bis (t-butylperoxypropyl) benzene, di-t-butylperoxy- Diisopropylbenzene, t-butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1-di t- butyl peroxy-3,3,5-trimethyl siloxane, and the like can be used n- butyl-4,4-di -t- butyl peroxy valerate. Of these, dicumyl peroxide, t-butylperoxybenzene and di-t-butylperoxy-diisopropylbenzene are preferred. Moreover, as a sulfur type vulcanizing agent, sulfur, morpholine disulfide, etc. can be used, for example. Of these, sulfur is preferred. These vulcanizing agents may be used alone or in combination of two or more.

  Vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Those containing at least one of them can be used. Examples of the sulfenamide system include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), DCBS (N, N′-dicyclohexyl-2-benzothiazolylsulfenamide), TBBS (N-tert-butyl). -2-benzothiazylsulfenamide), N, N-dicyclohexyl-2-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N, N-diisopropyl-2-benzothiazole A sulfenamide-based compound such as sulfenamide can be used. Examples of the thiazole type include MBT (2-mercaptobenzothiazole), MBTS (dibenzothiazyl disulfide), sodium salt of 2-mercaptobenzothiazole, zinc salt, copper salt, cyclohexylamine salt, 2- (2,4-dinitro). Thiazole compounds such as phenyl) mercaptobenzothiazole and 2- (2,6-diethyl-4-morpholinothio) benzothiazole can be used. Examples of thiurams include TMTD (tetramethylthiuram disulfide), tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram monosulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide. Further, thiuram compounds such as tetrabutylthiuram disulfide and pentamethylenethiuram tetrasulfide can be used. As the thiourea series, for example, thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, diortolylthiourea and the like can be used. Examples of guanidine-based compounds include guanidine-based compounds such as diphenylguanidine, diortolylguanidine, triphenylguanidine, orthotolylbiguanide, and diphenylguanidine phthalate. Examples of dithiocarbamate include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, zinc dipropyldithiocarbamate , Complex salt of zinc pentamethylenedithiocarbamate and piperidine, zinc hexadecyl (or octadecyl) isopropyldithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, piperidine pentamethylenedithiocarbamate, selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, diamyl Such as cadmium dithiocarbamate And the like can be used thiocarbamate compound. As the aldehyde-amine system or aldehyde-ammonia system, for example, an aldehyde-amine system or aldehyde-ammonia system compound such as acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reaction product, etc. is used. can do. As the imidazoline-based compound, for example, an imidazoline-based compound such as 2-mercaptoimidazoline can be used. As the xanthate type, for example, a xanthate type compound such as zinc dibutylxanthate can be used. These vulcanization accelerators may be used alone or in combination of two or more.

As the vulcanization acceleration aid, for example, zinc oxide, stearic acid and the like can be used.
As the anti-aging agent, amine-based, phenol-based, imidazole-based, carbamic acid metal salts, and the like can be appropriately selected and used.

  The rubber composition for a breaker of the present invention may contain a stearic acid metal salt. Examples of metal stearates include magnesium stearate, magnesium 12-hydroxystearate, calcium stearate, calcium 12-hydroxystearate, barium stearate, barium 12-hydroxystearate, zinc stearate, zinc 12-hydroxystearate, and the like. Can be mentioned. Among the metal stearates, alkaline earth metal salts of stearic acid are preferable from the viewpoint of heat resistance improvement effect and compatibility with epoxidized natural rubber, and calcium stearate, 12-hydroxycalcium stearate, barium stearate, 12- More preferred is barium hydroxystearate.

  Examples of the oil include process oil, vegetable oil and fat, or a mixture thereof. Examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil. Vegetable oils include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, pineapple, tall oil, corn oil, rice bran oil, bean flower oil, sesame oil, olive oil, Examples include sunflower oil, palm kernel oil, cocoon oil, jojoba oil, macadamia nut oil, safflower oil, tung oil, and the like.

  The rubber composition for a breaker according to the present invention is capable of both maintaining the properties desired for the rubber composition for a breaker such as durability and improving the workability while reducing the amount of a raw material derived from petroleum resources. It has become. Here, the improved “workability” was measured using a Picuma Tack Tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with the provisions of JIS-T 9233 (details such as measurement conditions will be described later). ) It means that the tackiness index calculated by the following formula from the adhesive strength of the unvulcanized rubber composition is 105 or more (more preferably 110 or more).

・ Adhesive index = (Adhesive strength of rubber composition of the present invention / Adhesive strength of reference compounded rubber composition) × 100
In addition, the reference | standard mixing | blending rubber composition in the said calculation formula points out the rubber composition mix | blended with the same composition as the rubber composition of this invention except not containing a terpene resin and a rosin resin.

  The present invention also provides a pneumatic tire provided with a breaker composed of the rubber composition for a breaker of the present invention as described above and a tire cord embedded in the rubber composition. Here, FIG. 1 is a schematic sectional view showing an example of the pneumatic tire of the present invention. The pneumatic tire 1 includes a tread portion 2, a pair of sidewall portions 3 extending inward in the tire radial direction from both ends of the tread portion 2, and a bead portion 4 positioned at an inner end of each sidewall portion 3. Prepare. In addition, a carcass 6 is bridged between the bead portions 4 and 4, and a breaker (belt layer) 7 that reinforces the tread portion 2 with a tagging effect is disposed outside the carcass 6 and in the tread portion 2. The

  The carcass 6 is formed of one or more carcass plies 6a in which the carcass cord is arranged at an angle of, for example, 70 to 90 ° with respect to the tire equator CO. The carcass ply 6a extends from the tread portion 2 to the sidewall portion. 3, the periphery of the bead core 5 of the bead portion 4 is folded back and locked from the inner side to the outer side in the tire axial direction.

  The breaker 7 comprises two or more belt plies 7a in which tire cords (belt cords) are arranged at an angle of, for example, 40 ° or less with respect to the tire equator CO, and each belt cord crosses between the plies. Are placed in a different way. If necessary, a band layer (not shown) for preventing lifting at both ends of the breaker 7 may be provided at least outside the breaker 7. At this time, the band layer is made of a low modulus organic fiber cord. The tire is formed by a continuous ply spirally wound substantially parallel to the tire equator CO.

  Further, a bead apex rubber 8 extending radially outward from the bead core 5 is disposed in the bead portion 4, and an inner liner rubber 9 forming a tire lumen surface is adjacent to the inside of the carcass 6. The outside of the carcass 6 is protected by clinch rubber 4G and sidewall rubber 3G. The rubber composition for a breaker of the present invention is used for the breaker (belt layer) 7.

  FIG. 1 illustrates a pneumatic tire for a passenger car, but the present invention is not limited to this, and is used for various vehicles such as a passenger car, a truck, a bus, and a heavy vehicle. Provided pneumatic tires.

  The pneumatic tire of the present invention is produced by a conventionally known method using the rubber composition for a breaker of the present invention. That is, a rubber composition for a breaker containing the above-described essential components and other compounding agents blended as necessary is kneaded and extruded in accordance with the shape of the tire breaker at an unvulcanized stage, This is stuck on the upper and lower sides of the tire cord and buried to produce a breaker, and then molded together with other members of the tire by a normal method on a tire molding machine to form an unvulcanized tire. The tire of the present invention can be obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

  The breaker in the tire of the present invention is not particularly limited as long as it uses the above-described rubber composition for a breaker of the present invention, and any conventionally known appropriate material can be used as a tire cord. It is.

  In the pneumatic tire of the present invention, the content ratio of components derived from petroleum resources in the breaker rubber is further reduced, sufficient consideration is given to resource saving and environmental protection, and good physical characteristics are maintained and processability is improved. Since the rubber composition that is compatible with the improvement of the above is used, it is an “eco-tyre” that is friendly to the global environment, has improved processability, and has desired properties such as durability and steel adhesion.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

<Example 1 and Comparative Examples 1 and 2>
In accordance with the formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel Co., Ltd., the components other than sulfur and vulcanization accelerator were filled so that the filling rate would be 58%, and the rotational speed was 80 rpm. And kneading for 3 minutes until reaching 140 ° C. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded material in the amounts shown in Table 1, and then kneaded for 5 minutes at 80 ° C. using an open roll. Example 1 and Comparative Examples 1 and 2 Thus, an unvulcanized rubber composition blended according to the above was obtained.

The details of various blending components used in Examples and Comparative Examples are as follows.
(1) Natural rubber (NR): RSS # 3 (manufactured by Tech Behang)
(2) Carbon black: Show black N220 (manufactured by Cabot Japan)
(3) Silica: Ultrazil VN3 (Degussa)
(4) Silane coupling agent: Si69 (Degussa)
(5) Wax: Sunnock wax (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
(6) Resin (1): Petroleum resin (Marcaretz T100AS (manufactured by Maruzen Petrochemical Co., Ltd.))
(7) Resin (2): Terpene resin (PX300N (manufactured by Yasuhara Chemical Co., Ltd.))
(8) Anti-aging agent: Santoflex 6PPD (manufactured by Flexis)
(9) Stearic acid: Paulownia (Nippon Yushi Co., Ltd.)
(10) Zinc oxide: Zinc flower (Mitsui Metal Mining Co., Ltd.)
(11) Sulfur: Powdered sulfur (manufactured by Tsurumi Chemical Co., Ltd.)
(12) Vulcanization accelerator: Noxeller DZ-G (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
The following tests were conducted on the unvulcanized rubber compositions obtained in the examples and comparative examples. Table 1 also shows the test results.

(Adhesion test)
In accordance with the provisions of JIS-T 9233, using a Pikuma tack tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), measurement temperature 23 ° C., load 4.9 N, standing time 10 seconds, peeling speed 30 mm / min. Under the conditions, the adhesive strength [N] of the unvulcanized rubber composition was measured. Furthermore, the adhesive index of the rubber composition of Comparative Example 1 as a reference compounded rubber composition was set to 100, and the adhesive strength was displayed as an index according to the following calculation formula. The greater the tack index, the greater the adhesive strength and the better.

・ Adhesiveness index = (adhesive strength of each example, comparative example / adhesive strength of reference blend) × 100
It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic sectional drawing which shows an example of the pneumatic tire of this invention.

Explanation of symbols

  1 tire, 2 tread part, 3 side wall part, 3G side wall rubber, 4 bead part, 5 bead core, 6 carcass, 6a carcass ply, 7 breaker (belt layer), 8 bead apex rubber, 9 inner liner rubber.

Claims (4)

Including at least one of a rubber component and 20 to 60 parts by mass of silica, 0.5 to 15 parts by mass of a terpene resin and a rosin resin with respect to 100 parts by mass of the rubber component;
A rubber composition for a breaker, wherein the rubber component contains a natural rubber component composed of at least one of natural rubber and modified natural rubber within a range of 30 to 100% by mass.   The rubber composition for a breaker according to claim 1, wherein the modified natural rubber is an epoxidized natural rubber.   The rubber composition for a breaker according to claim 1 or 2, wherein the rubber component comprises the natural rubber component.   A pneumatic tire provided with the breaker comprised from the rubber composition in any one of Claims 1-3, and the cord for tires embed | buried under the said rubber composition.

Images