JP2008031427A - Rubber composition and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition excellent in processability, low fuel consumption, complex modulus and durability, and tires prepared by using the same. <P>SOLUTION: The rubber composition comprises 2 to 2.9 parts by weight of (B) sulfur, 0.6 to 10 parts by weight of (C) at least one compound selected from the group consisting of a cresol resin, a resorcin condensate and a modified resorcin condensate, and 10 to 55 parts by weight of (D) carbon black and/or silica, based on 100 parts by weight of (A) a rubber component that contains a natural rubber and/or isoprene rubber and further contains at least two kinds of synthetic rubbers selected from the group consisting of a butadiene rubber, modified butadiene rubber, styrene-butadiene rubber and modified styrene-butadiene rubber. The tire using the rubber composition is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire using the rubber composition.

  In recent years, tires are increasingly required to improve steering stability such as braking performance particularly during high-speed driving and riding comfort performance.

As a method for improving steering stability in a rubber composition for covering a fiber cord, a method for improving a complex elastic modulus (E ^* ) and improving rigidity is known. Specifically, a method of blending a phenol resin is known. However, there is a problem that the rolling resistance (tan δ) of the rubber composition increases.

Methods for improving E ^* and reducing tan δ include resorcin condensates and modified resorcin condensates, hexamethylol melamine pentamethyl ether (HMMPME) partial condensate and hexamethoxymethylol melamine (HMMM) partial condensate. The method of cross-linking with is generally known. However, in that case, during the production process of the rubber composition, crosslinking starts at the time of the sheet or topping process, and the rubber viscosity increases, so that the workability deteriorates.

In addition, as a technique for improving E ^* and reducing tan δ, a technique for highly blending sulfur and a technique for blending a vulcanization accelerator at high levels are also known. However, a natural effect becomes remarkable at the time of driving | running | working and durability will deteriorate.

  Furthermore, in recent years, fuel-efficient tires with excellent fuel efficiency have been demanded, and techniques for improving fuel efficiency by improving treads and sidewalls have been actively developed.

  However, as fuel efficiency of large-sized members such as treads and sidewalls progresses, as a result, the contribution rate of cord topping rubber to fuel efficiency increases.

  It has become clear that reducing tan δ is effective for reducing the fuel consumption of cord topping rubber by FEM analysis, etc., but there is an effective technique for reducing tan δ in cord topping rubber do not do.

  As a method for reducing tan δ, there are a method for reducing the blending amount of carbon black, a method for increasing the blending amount of oil, and the like. However, if the blending amount of carbon black is reduced, the breaking characteristics will be lowered, and if the blending amount of oil is increased, not only the breaking characteristics will be degraded, but also adjacent members such as sidewalls, inner liners, cushion rubbers, etc. The oil moves and the durability deteriorates.

  Patent Document 1 discloses a rubber composition that contains a compound capable of donating a methylene group and a resorcin resin and is suitably used for a breaker edge portion. However, since the rubber component contains only natural rubber and / or isoprene rubber and is high sulfur (4 to 6 parts by weight), it causes a decrease in physical properties due to reversion during high temperature vulcanization. There is still room for improvement.

JP 2004-217817 A

  The present invention provides a rubber composition having sufficient hardness, excellent workability and roll workability, low exothermic property, elongation at break, complex elastic modulus and durability, and a tire using the same. With the goal.

  The present invention contains (A) natural rubber and / or isoprene rubber, and further contains at least two synthetic rubbers selected from the group consisting of butadiene rubber, modified butadiene rubber, styrene butadiene rubber and modified styrene butadiene rubber. At least one compound selected from the group consisting of (B) 2 to 2.9 parts by weight of sulfur, (C) a cresol resin, a resorcin condensate and a modified resorcin condensate with respect to 100 parts by weight of the rubber component. The present invention relates to a rubber composition containing 6 to 10 parts by weight and (D) 10 to 55 parts by weight of carbon black and / or silica.

  The rubber composition further preferably contains 0.1 to 3 parts by weight of (E) hexamethylenetetramine with respect to 100 parts by weight of the rubber component (A).

  The rubber composition further contains 0.5 to 3 of (F) a partial condensate of hexamethylol melamine pentamethyl ether or a partial condensate of hexamethoxymethylol melamine with respect to 100 parts by weight of the rubber component (A). It is preferable to contain by weight.

  The rubber composition preferably contains a modified butadiene rubber or a modified styrene butadiene rubber as a synthetic rubber.

  The rubber composition preferably contains a modified butadiene rubber and a modified styrene butadiene rubber as synthetic rubber.

  The rubber component (A) of the rubber composition preferably contains 40-80% by weight of natural rubber and / or isoprene rubber and 10-30% by weight of modified butadiene rubber.

  The rubber composition of the present invention is preferably used as a carcass or a belt by covering a fiber cord.

  The present invention also relates to a tire using the rubber composition.

  According to the present invention, at least one compound (C) selected from the group consisting of a predetermined rubber component (A), sulfur (B), cresol resin, resorcin condensate and modified resorcin condensate and carbon black and / or By containing a predetermined amount of silica (D), sufficient hardness can be obtained, rubber properties excellent in workability, roll workability, low fuel consumption, elongation at break, complex elastic modulus and durability, and A tire using the tire can be provided.

  The rubber composition of the present invention comprises (A) a rubber component, (B) sulfur, (C) a cresol resin, a resorcin condensate and a modified resorcin condensate, and (D) carbon black. And / or silica.

  The rubber component (A) includes natural rubber (NR) and / or isoprene rubber (IR), butadiene rubber (BR), modified butadiene rubber (modified BR), styrene butadiene rubber (SBR) and modified styrene butadiene rubber (modified). At least two synthetic rubbers selected from the group consisting of SBR).

  The NR is not particularly limited, and those usually used in the rubber industry can be used. Specific examples include RSS # 3 and TSR20. Also, IR is not particularly limited, and those conventionally used in the tire industry can be used.

  The content of NR and / or IR in the rubber component (A) is preferably 40% by weight or more, and more preferably 50% by weight or more. When the content of NR and / or IR is less than 40% by weight, the elongation at break in the tensile test is lowered, and the rubber composition tends to break when it comes into contact with road surface irregularities and foreign matter during running. . The content of NR and / or IR in the rubber component (A) is preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 75% by weight or less. If the content of NR and / or IR exceeds 90% by weight, reversion will occur during high temperature vulcanization, or weakening of the polymer structure will occur, such as transition of the 100% cis structure to the trans structure. Rubber properties such as elongation tend to decrease.

  There is no restriction | limiting in particular as BR, BR (High cis BR) of high cis content, such as BR130B and BR150B made from Ube Industries, Ltd., can be used conveniently. In view of excellent crack growth resistance, the BR content in the rubber component (A) is preferably 10% by weight or more, and more preferably 15% by weight or more. In addition, the content of BR in the rubber component (A) is 50% by weight or less in that the elongation at break is excellent and the crack growth resistance is saturated and does not improve even if blended more than that. Preferably, it is 40% by weight or less.

  As the modified BR, one obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further having a modified BR molecule terminally bonded by a tin-carbon bond is preferable. .

  Examples of the lithium initiator include lithium compounds such as alkyl lithium, aryl lithium, vinyl lithium, organic tin lithium, and organic nitrogen lithium compounds, and lithium metal. By using the lithium initiator as a modified BR initiator, a modified BR having a high vinyl content and a low cis content can be produced.

  Tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyldibutyltin, triphenyltin ethoxide, diphenyldimethyltin, ditolyltin chloride, diphenyltin dioctano Ate, divinyldiethyltin, tetrabenzyltin, dibutyltin distearate, tetraallyltin, p-tributyltin styrene, etc. These tin compounds may be used alone or in combination of two or more. Good.

  The content of tin atoms in the modified BR is preferably 50 ppm or more, and more preferably 60 ppm or more. If the tin atom content is less than 50 ppm, the effect of promoting the dispersion of carbon black in the modified BR is small, and tan δ tends to increase. The tin atom content is preferably 3000 ppm or less, more preferably 2500 ppm or less, and even more preferably 250 ppm or less. When the content of tin atoms exceeds 3000 ppm, the kneaded product is not well-organized and the edges are not aligned, so that the extrudability of the kneaded product tends to deteriorate.

  The molecular weight distribution (Mw / Mn) of the modified BR is preferably 2 or less, and more preferably 1.5 or less. If the Mw / Mn of the modified BR exceeds 2, the dispersibility of the carbon black tends to deteriorate and tan δ tends to increase. The vinyl bond amount of the modified BR is preferably 5% by weight or more, and more preferably 7% by weight or more. If the amount of vinyl bonds in the modified BR is less than 5% by weight, it tends to be difficult to polymerize (produce) the modified BR. Further, the vinyl bond amount of the modified BR is preferably 50% by weight or less, and more preferably 20% by weight or less. When the vinyl bond content of the modified BR exceeds 50% by weight, the dispersibility of carbon black tends to deteriorate and the tensile strength tends to decrease.

  The content of the modified BR in the rubber component (A) is preferably 10% by weight or more, and more preferably 15% by weight or more. When the content of the modified BR is less than 10% by weight, sufficient crack growth resistance tends not to be obtained. Further, the content of the modified BR in the rubber component (A) is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 30% by weight or less. If the content of the modified BR exceeds 50% by weight, even if the content of the modified BR is increased, the crack growth resistance is saturated and does not improve, and the elongation at break tends to decrease.

  Examples of the modified BR that satisfies the above conditions include BR1250H manufactured by Nippon Zeon Co., Ltd.

  There is no restriction | limiting in particular as SBR, Emulsion polymerization SBR (E-SBR) or solution polymerization SBR (S-SBR) can be used.

  The content of SBR in the rubber component (A) is preferably 10% by weight or more, and more preferably 15% by weight or more. If the SBR content is less than 10% by weight, the effect of suppressing reversion tends to be insufficient. Further, the content of SBR in the rubber component (A) is preferably 50% by weight or less, and more preferably 40% by weight or less. When the SBR content exceeds 50% by weight, the breaking strength tends to decrease.

  The modified SBR preferably has a small amount of bound styrene, such as HPR340 manufactured by JSR Corporation.

  The bound styrene content of the modified SBR is preferably 5% by weight or more, and more preferably 7% by weight or more, from the viewpoint of excellent reversion properties in rubber blending. The amount of bound styrene of the modified SBR is preferably 30% by weight or less, more preferably 20% by weight or less, from the viewpoint of excellent low heat build-up.

  Examples of the modified SBR include emulsion polymerization modified SBR (modified E-SBR) and solution polymerization modified SBR (modified S-SBR). However, by enhancing the bond between silica and the polymer chain and reducing tan δ, low fuel consumption can be achieved. Modified S-SBR is preferred because it can be improved.

  As the modified SBR, those coupled with tin or silicon are preferably used. As a coupling method of the modified SBR, for example, an alkali metal (such as Li) or an alkaline earth metal (such as Mg) at the molecular chain end of the modified SBR is reacted with tin halide or silicon halide according to a conventional method. Methods.

  The modified SBR is a (co) polymer obtained by (co) polymerizing a conjugated diolefin alone or a conjugated diolefin and an aromatic vinyl compound, and has a primary amino group or an alkoxysilyl group. preferable.

  The primary amino group may be bonded to any of the polymerization initiation terminal, the polymerization termination terminal, the polymer main chain, and the side chain, but it can suppress the energy loss from the polymer terminal and improve the hysteresis loss characteristics. From this point, it is preferably introduced at the polymerization initiation terminal or the polymerization termination terminal.

  The weight average molecular weight (Mw) of the modified SBR is preferably 1,000,000 or more, more preferably 1,200,000 or more, from the viewpoint that sufficient breaking characteristics can be obtained. The Mw of the modified SBR is preferably 2 million or less and more preferably 1.8 million or less from the viewpoint that the viscosity of the rubber can be adjusted to facilitate kneading.

  The content of the modified SBR in the rubber component (A) is preferably 10% by weight or more, and more preferably 15% by weight or more. When the content of the modified SBR is less than 10% by weight, the reversion property is inferior and tan δ tends to deteriorate. Further, the content of the modified SBR in the rubber component (A) is preferably 40% by weight or less, and more preferably 35% by weight or less. When the content of the modified SBR exceeds 40% by weight, the breaking strength tends to decrease.

  Of the synthetic rubbers selected from the group consisting of BR, modified BR, SBR, and modified SBR, when SBR is contained, reversion is difficult to occur and the hardness can be maintained. Excellent in properties. In addition, when modified BR is contained, the interaction with carbon black is excellent, and the bond between carbon black and polymer chain can be strengthened, and the modified SBR has an excellent interaction with silica and strengthens the bond between silica and polymer chain Can do. The present invention contains at least two kinds of synthetic rubbers selected from the group consisting of BR, modified BR, SBR and modified SBR as the rubber component (A). When carbon black or silica is included, the fuel efficiency is reduced. From the viewpoint that the breaking strength may be improved, it is preferable to contain modified BR or modified SBR, and it is preferable to contain both modified BR and modified SBR.

  In addition to the NR, IR, BR, modified BR, SBR, and modified SBR, the rubber component (A) includes acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and ethylene propylene conventionally used in the tire industry. Other rubber components such as diene rubber (EPDM) and styrene isoprene butadiene rubber (SIBR) can also be used.

  The content of the other rubber component in the rubber component (A) is preferably 20% by weight or less, and more preferably 15% by weight or less from the viewpoint of maintaining crack growth and processability and being excellent in deterioration. In addition, it is not necessary to contain other rubber components.

As sulfur (B), sulfur generally used at the time of vulcanization in the rubber industry can be used, but insoluble sulfur is particularly preferable. Here, the insoluble sulfur refers to sulfur obtained by heating and quenching natural sulfur S ₈ to increase the molecular weight so that S _x (x = 100,000 to 300,000) is obtained. By using insoluble sulfur, blooming that normally occurs when sulfur is used as a rubber vulcanizing agent can be prevented.

  The content of sulfur (B) is 2 parts by weight or more, preferably 2.4 parts by weight or more with respect to 100 parts by weight of the rubber component (A). When the content of sulfur (B) is less than 2 parts by weight, sufficient sulfur is not supplied to the adhesive layer with the carcass fiber cord, resulting in poor adhesion. Further, the content of sulfur (B) is 2.9 parts by weight or less, preferably 2.8 parts by weight or less with respect to 100 parts by weight of the rubber component (A). When the sulfur content exceeds 2.9 parts by weight, the density of sulfur cross-linking increases, and the breaking characteristics such as breaking resistance and elongation at break, particularly the breaking characteristics after thermal oxidative degradation decrease.

  The rubber composition of the present invention contains one or more compounds (C) selected from the group consisting of a cresol resin, a resorcin condensate and a modified resorcin condensate (hereinafter referred to as compound (C)).

  The cresol resin has a chemical softening point of around 100 ° C. (92 to 107 ° C.), so it is solid at room temperature, but is easy to disperse because it is liquid when kneaded with rubber, and further, hexamethylenetetramine used in the present invention. It is most preferable to use a metacresol resin represented by the following chemical formula because the reaction start temperature with (HMT) is appropriate at around 130 ° C. and at a tire vulcanization temperature (145 to 190 ° C.) or less.

  N in the formula is preferably 1 or more, and more preferably 2 or more. Further, n in the formula is preferably 5 or less.

  Examples of such a cresol resin include SUMICANOL 610 manufactured by Sumitomo Chemical Co., Ltd.

  The resorcin condensate refers to a compound represented by the following chemical formula.

  The modified resorcin condensate is a condensate having a terminal resorcin and a repeating unit having resorcin or alkylphenol as shown in the following chemical formula.

  N in Chemical Formula 2 and Chemical Formula 3 is an integer. n is preferably 2 to 5 from the viewpoint of good dispersibility in rubber.

  R in Chemical Formula 3 is an alkyl group, and the number of carbon atoms is preferably 9 or less, more preferably 8 or less. Specific examples of the alkyl group represented by R in Chemical Formula 3 include a methyl group, an ethyl group, and an octyl group. The modified resorcin condensate may be a mixture of resorcin and alkylphenol as a repeating unit.

  Examples of the modified resorcin condensate include resorcin / alkylphenol / formalin copolymer (such as Sumikanol 620 manufactured by Sumitomo Chemical Co., Ltd.), resorcin / formalin reaction product penacolite resin (such as 1319S manufactured by India Spec). It is done.

  The content of the compound (C) is 0.6 parts by weight or more, preferably 1 part by weight or more, more preferably 3 parts by weight or more with respect to 100 parts by weight of the rubber component (A). If the amount is less than 0.6 parts by weight, sufficient hardness cannot be obtained. The content of the compound (C) is 10 parts by weight or less, preferably 8 parts by weight or less with respect to 100 parts by weight of the rubber component (A). When the content of the compound (C) exceeds 10 parts by weight, the hardness becomes too high, and the crack growth resistance and elongation at break decrease.

  Carbon black and / or silica (D) is not particularly limited, and grades of carbon black and silica such as SAF, ISAF, HAF, and FEF conventionally used in the tire industry can be used.

  The content of carbon black and / or silica (D) is 10 parts by weight or more, preferably 25 parts by weight or more with respect to 100 parts by weight of the rubber component (A). If the content of carbon black and / or silica (D) is less than 10 parts by weight, the hardness and breaking strength tend to be insufficient. The content of carbon black and / or silica (D) is 55 parts by weight or less, preferably 50 parts by weight or less with respect to 100 parts by weight of the rubber component (A). When the content of carbon black and / or silica (D) exceeds 55 parts by weight, the exothermic property tends to increase.

  When silica is used, it is preferable to use a silane coupling agent in combination.

  The silane coupling agent is not particularly limited, and any silane coupling agent that has been conventionally blended with silica in a rubber composition in the tire industry can be used. Specifically, bis (3-triethoxysilyl) can be used. Propyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) Tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide Bis (3-trimethoxysilyl Propyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, 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-trimethoxysilyl Propyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl Sulfide type such as methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, etc. Mercapto, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl, 3-aminopropyltriethoxysilane, 3-aminopropyltrimeth Amino, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyl, such as silane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane Glycidoxy type such as trimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3 -Chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, and other chloro-based ones. These silane coupling agents can be used alone. 2 or more types It may be used in combination. Of these, bis- (3-triethoxysilylpropyl) -tetrasulfide, bis (3-triethoxysilylpropyl) disulfide and the like are preferably used.

  When the silane coupling agent is blended, the content of the silane coupling agent is preferably 6 parts by weight or more and more preferably 8 parts by weight or more with respect to 100 parts by weight of silica from the viewpoint of excellent processability and heat build-up. The content of the silane coupling agent is such that if the silane coupling agent is added excessively, the excess coupling agent releases sulfur and excessively crosslinks the rubber, so that the breaking strength is reduced and the cost is increased. In this respect, 12 parts by weight or less is preferable and 10 parts by weight or less is more preferable with respect to 100 parts by weight of silica.

  In the present invention, when the crosslinking starts during the processing of the sheet or topping, the rubber viscosity increases and the processability decreases. Therefore, in the present invention, hexamethylenetetramine (HMT) (E) that does not decompose at the processing temperature (90 to 140 ° C.) ) Is preferably contained.

  The content of hexamethylenetetramine (HMT) (E) is preferably 0.1 parts by weight or more and more preferably 0.5 parts by weight or more with respect to 100 parts by weight of the rubber component (A). When the content of hexamethylenetetramine (HMT) (E) is less than 0.1 part by weight, there is a tendency that sufficient crosslinking of the compound (C) and thus the hardness of the rubber composition cannot be obtained. Further, the content of hexamethylenetetramine (HMT) (E) is preferably 3 parts by weight or less, and more preferably 2.5 parts by weight or less with respect to 100 parts by weight of the rubber component (A). When the content of hexamethylenetetramine (HMT) (E) exceeds 3 parts by weight, ammonia generated during thermal decomposition destroys the adhesive layer between the cord and the rubber, resulting in a decrease in rubber attachment.

  In the present invention, when hexamethylenetetramine (HMT) is decomposed into formalin and ammonia, ammonia can be rendered harmless and the cord adhesion can be improved. Therefore, a partial condensate of hexamethylolmelamine pentamethyl ether (HMMPME) You may contain the partial condensate (F) (henceforth a compound (F)) of a methoxymethylol melamine (HMMM).

  The partial condensate of HMMPME means what is represented by the following chemical formula.

(In the formula, n is an integer, and n is usually 1 to 3)
The partial condensate of HMMM means what is represented by the following chemical formula.

(In the formula, n is an integer, and n is usually 1 to 3.)

  The content of the compound (F) is preferably 0.5 parts by weight or more and more preferably 0.7 parts by weight or more with respect to 100 parts by weight of the rubber component (A). When the content of the compound (F) is less than 0.5 parts by weight, sufficient hardness tends not to be obtained. Further, the content of the compound (F) is preferably 3 parts by weight or less, and more preferably 2 parts by weight or less with respect to 100 parts by weight of the rubber component (A). When the content of the compound (F) exceeds 3 parts by weight, crosslinking starts during rubber kneading or sheet processing, and the viscosity of the compounded rubber tends to increase.

  The rubber composition of the present invention can contain reinforcing fillers other than carbon black and silica such as calcium carbonate, aluminum hydroxide, clay, talc, and alumina. These reinforcing fillers may be blended alone or in combination of two or more.

  The content of the reinforcing filler other than carbon black and silica is preferably 5 parts by weight or more and more preferably 7 parts by weight or more with respect to 100 parts by weight of the rubber component (A). If the content of the reinforcing filler is less than 5 parts by weight, the breaking strength tends not to be improved. Further, the content of the reinforcing filler other than carbon black and silica is preferably 50 parts by weight or less, more preferably 40 parts by weight or less with respect to 100 parts by weight of the rubber component (A). When the content of the reinforcing filler exceeds 50 parts by weight, the hardness becomes too high and the elongation at break tends to decrease.

  The rubber composition of the present invention comprises the rubber component (A), sulfur (B), compound (C), carbon black and / or silica (D), hexamethylenetetramine (HMT) (E), compound (F), In addition to the reinforcing filler, compounding agents usually used in the rubber industry, for example, aroma oil, various anti-aging agents, zinc oxide, stearic acid, various vulcanization accelerators and the like can be appropriately mixed.

  The rubber composition of the present invention can be used for various members such as a carcass, a belt, a bead apex, a clinch apex, a band, and the like. It is preferably used as a carcass or a belt because it has excellent growth properties. When the rubber composition of the present invention is used as a carcass or a belt, a fiber cord is coated with the rubber composition to form a carcass or a belt, and then bonded to another tire member to form an unvulcanized tire, By vulcanization, a tire can be manufactured.

  The fiber cord refers to a fiber cord that is coated with the rubber composition of the present invention when the rubber composition of the present invention is used as a carcass or a belt. Specifically, it is obtained from raw materials such as polyester, nylon, rayon, polyethylene terephthalate, and aramid. Among them, polyester and aramid are preferable as the raw material for the fiber cord because of excellent thermal stability and low cost.

  The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Natural rubber (NR): RSS # 3
Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd.
Modified butadiene rubber (modified BR): Nipol BR1250H manufactured by Nippon Zeon Co., Ltd. (lithium initiator: lithium, tin atom content: 250 ppm, Mw / Mn: 1.5, vinyl bond content: 10-13 wt%)
Styrene butadiene rubber (SBR): Nipol 1502 manufactured by Nippon Zeon Co., Ltd.
Modified styrene butadiene rubber (modified SBR): HPR340 manufactured by JSR Corporation (modified S-SBR, amount of bonded styrene: 10% by weight, coupled with alkoxyl silane, introduced at the end)
Insoluble sulfur: Kristex HSOT 20 (insoluble sulfur containing 80% sulfur and 20% oil) by Flexis
Metacresol resin: Sumikanol 610 manufactured by Sumitomo Chemical Co., Ltd. (n = 16 to 17 in chemical formula 1)
Modified resorcin resin: Sumikanol 620 (resorcin / alkylphenol condensate) manufactured by Sumitomo Chemical Co., Ltd.

(In the formula, R is a methyl group, an octyl group or a hydroxyl group, and these may be present together.)
Carbon Black 1: Show Black N326 manufactured by Cabot Japan
Carbon Black 2: Show Black N330 manufactured by Cabot Japan
Hexamethylenetetramine (HMT): Noxeller H manufactured by Ouchi Shinsei Chemical Co., Ltd.
Partial condensate of hexamethoxymethylol melamine pentamethyl ether (HMMPME): effective resin content of Sumikanol 507A (mixture of about 65% of a substance having a methylene group and silica and oil) manufactured by Sumitomo Chemical Co., Ltd. (formula (4):

(In the formula, n is an integer of 1 to 3)
Silica: 115Gr made by Rhodia
Aroma oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: NOCRACK 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Zinc oxide: Silver candy R made by Toho Zinc Co., Ltd.
Stearic acid: Koji vulcanization accelerator manufactured by NOF Corporation: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfanamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
N-cyclohexylthio-phthalimide (CTP): Retarder CTP manufactured by Ouchi Shinsei Chemical Co., Ltd.

Examples 1-14 and Comparative Examples 1-11
In accordance with the formulation shown in Table 1, various chemicals except insoluble sulfur and a vulcanization accelerator (HMT, a partial condensate of HMMPME and CTP, which are also blended) were kneaded with a Banbury mixer. To the obtained kneaded product, insoluble sulfur and a vulcanization accelerator (added when HMT, HMMPME partial condensate and CTP are added) are kneaded with an open roll, and an unvulcanized rubber composition Got. The vulcanized rubber compositions of Examples 1 to 14 and Comparative Examples 1 to 11 were obtained by press vulcanizing the unvulcanized rubber composition at 170 ° C. for 12 minutes.

(Mooney viscosity)
A test piece of a predetermined size was prepared from the unvulcanized rubber composition, and it was used for 1 minute using a Mooney viscosity tester manufactured by Shimadzu Corporation according to JIS K 6300 “Testing method for unvulcanized rubber”. The Mooney viscosity (ML _{1 + 4} ) of the unvulcanized rubber composition was measured when 4 minutes passed by rotating the small rotor under the temperature condition of 130 ° C. heated by the preheating. In addition, it shows that it is excellent in workability, so that Mooney viscosity is small.

(Viscoelasticity test)
Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., the complex elastic modulus E ^* and loss tangent tan δ of the vulcanized rubber composition at 70 ° C. under conditions of initial strain of 10%, dynamic strain of 2% and frequency of 10 Hz. Was measured. In addition, it shows that rigidity is high and it is excellent in steering stability, so that E ^* is large, and it shows that it is excellent in low heat generation property so that tan-delta is small.

(Tensile test)
In accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber-Determination of Tensile Properties”, a tensile test was conducted using a No. 3 dumbbell-shaped test piece made of the vulcanized rubber composition, and each test piece was broken. The time elongation E _B (%) was measured. Moreover, about the vulcanized rubber composition of Examples 1-6 and Comparative Examples 1-6, about the test piece after carrying out thermal oxidation degradation for 48 hours on the conditions of the temperature of 100 degreeC using a thermal oven, The elongation at break E _B (%) was measured. In addition, it shows that it is excellent, so that EB is large.

(Adhesion test)
Fiber cord (resin resin film formed by dip treatment) by dipping polyester fiber (raw material: terephthalic acid and ethylene glycol) manufactured by Teijin Limited into resorcin and formaldehyde mixture liquid composition of unvulcanized rubber After forming an unvulcanized carcass by coating with an object, the carcass was produced by vulcanization at 170 ° C. for 12 minutes.

An adhesion test was performed using the obtained carcass, and the peel resistance between the carcass and the fiber cord measured by a tensile tester (manufactured by Instron) was measured. And the adhesive index of the comparative example 1 was set to 100, and the peeling resistance of each mixing | blending was displayed as an index | exponent with the following formula.
(Adhesiveness index) = (Peel resistance of each formulation) / (Peel resistance of Comparative Example 1) × 100

(Roll workability)
In the kneading step in the open roll, the winding of the unvulcanized rubber composition with respect to the roll was visually evaluated, the roll workability index of Comparative Example 7 was set to 100, and the roll workability of each formulation was displayed as an index. . In addition, it shows that kneading | mixing in an open roll progresses to lubrication and it is excellent in workability, so that a roll workability | operativity index is large.

(Rubber hardness)
It was measured with a type A durometer according to JIS K 6253 “Method for testing hardness of vulcanized rubber and thermoplastic rubber”.

(High load durability drum test)
Fiber cord (Teijin's polyester (raw materials: terephthalic acid and ethylene glycol) is coated with the unvulcanized rubber composition to form an unvulcanized carcass, which is then bonded to other tire members and unvulcanized. A vulcanized tire was molded and vulcanized at 170 ° C. for 12 minutes to produce a commercial vehicle truck tire (tire size: 225 / 70R16 117/115).

Under the condition of 230% load of the maximum load (maximum internal pressure condition) of the JIS standard, the tire was run at a speed of 20 km / h, and the travel distance until the bead or tread was swollen was measured. The load durability index was set to 100, and the travel distance of each formulation was indicated by an index according to the following calculation formula. In addition, it shows that durability of a bead part or a tread part is excellent and it is favorable, so that a high load durability index is large.
(High load durability index) = (travel distance of each formulation) / (travel distance of Comparative Example 7) × 100

  The evaluation results are shown in Tables 1 and 2.

Claims (8)

(A) A rubber component containing natural rubber and / or isoprene rubber, and further containing at least two kinds of synthetic rubbers selected from the group consisting of butadiene rubber, modified butadiene rubber, styrene butadiene rubber and modified styrene butadiene rubber Against
(B) 2 to 2.9 parts by weight of sulfur,
(C) 0.6 to 10 parts by weight of at least one compound selected from the group consisting of cresol resin, resorcin condensate and modified resorcin condensate, and (D) 10 to 55 parts by weight of carbon black and / or silica. Containing rubber composition. The rubber composition according to claim 1, further comprising 0.1 to 3 parts by weight of (E) hexamethylenetetramine with respect to 100 parts by weight of the rubber component (A). Furthermore, 0.5 to 3 parts by weight or less of (F) a partial condensate of hexamethylol melamine pentamethyl ether or a partial condensate of hexamethoxymethylol melamine is contained per 100 parts by weight of the rubber component (A). Or the rubber composition of 2. The rubber composition according to any one of claims 1 to 3, wherein the rubber component (A) contains a modified butadiene rubber or a modified styrene butadiene rubber as a synthetic rubber. The rubber composition according to any one of claims 1 to 3, wherein the rubber component (A) contains a modified butadiene rubber and a modified styrene butadiene rubber as a synthetic rubber. The rubber composition according to any one of claims 1 to 5, wherein the rubber component (A) contains 40 to 80% by weight of natural rubber and / or isoprene rubber and 10 to 30% by weight of modified butadiene rubber. The rubber composition according to any one of claims 1 to 6, which is used as a carcass or a belt by covering a fiber cord. A tire using the rubber composition according to claim 1.