JP6249718B2 - Rubber composition, tire member and tire using the same - Google Patents

Description

  The present invention relates to a rubber composition, a tire member composed of the rubber composition, and a tire including the tire member.

  In recent years, there has been an increasing demand for tires to improve wear resistance. Conventionally, as a means for improving the wear resistance of a tire, a tire including a tire member such as a tread made of a rubber composition containing a high-cis butadiene rubber (high-cis BR) as a rubber component is used. Are known. However, when high cis BR is contained, there is a problem that workability is lowered, filler dispersion is deteriorated, and rolling resistance characteristics (low fuel consumption) are deteriorated.

  Further, in the rubber composition constituting the tire, carbon black that can easily interact with the rubber component and has an excellent reinforcing effect has been used as a filler. From the viewpoint, white fillers such as silica are used instead of carbon black.

  However, white fillers such as silica have a lower affinity with natural rubber, butadiene rubber, styrene butadiene rubber, etc., which are widely used for tires, compared to carbon black, and wear resistance and mechanical strength (tensile strength and fracture) Often inferior in terms of elongation.

  As a method for solving this problem, it has been proposed to incorporate a silane coupling agent having reactivity with a white filler such as a rubber component and silica, but the reaction with the white filler is sufficiently advanced. However, the unreacted white filler remains in a poorly dispersed state and the desired performance is not exhibited.

  Here, in order to improve the dispersibility of the white filler, the processability of the rubber component is an important issue. As a method for improving processability, it is generally used that stearic acid is contained (see Non-Patent Document 1), but the improvement effect on a rubber component that is inferior in filler dispersibility such as Hicis BR is small, such as silica Even when the white filler is contained, a rubber composition capable of improving the wear resistance, processability and fuel efficiency in a well-balanced manner has not been obtained.

Satoshi Onuki, Journal of the Japan Rubber Association, 2009, Vol. 82, No. 2, “Rubber compounding and processing aids”, P50-55

  The present invention solves the above problems and can improve the wear resistance, processability and fuel efficiency in a well-balanced manner, a tire composition comprising the rubber composition, and a tire comprising the tire member The purpose is to provide.

  The present invention relates to a rubber component containing a butadiene rubber having a cis content of 90% by mass or more and a rubber composition containing hydroxystearic acid and / or a derivative thereof.

  The hydroxy stearic acid derivative is preferably a hydroxy stearic acid magnesium salt.

  The rubber composition preferably further contains silica.

  The present invention relates to a tire member composed of the rubber composition.

  Moreover, this invention relates to a tire provided with the said tire member.

  According to the present invention, a rubber component containing a predetermined butadiene rubber and a hydroxystearic acid and / or a derivative thereof can improve the wear resistance, processability and fuel efficiency in a well-balanced manner. There can be provided a composition, a tire member composed of the rubber composition, and a tire including the tire member.

  The rubber composition of the present invention is characterized by containing a rubber component containing a butadiene rubber having a cis content of 90% by mass or more, and hydroxystearic acid and / or a derivative thereof.

  The cis content of the high cis BR is 90% by mass or more, and is preferably 95% by mass or more, more preferably 97% by mass or more, and still more preferably 98% by mass or more from the viewpoint of improving wear resistance.

The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the high cis BR is preferably 10 or more, and more preferably 30 or more. When the Mooney viscosity is less than 10, the dispersibility of the filler tends to decrease. The Mooney viscosity is preferably 120 or less, and more preferably 80 or less. If the Mooney viscosity exceeds 120, rubber burn (discoloration) may occur during extrusion. In addition, the Mooney viscosity of the high cis BR in this specification is measured according to ISO 289 and JIS K6300.

  The molecular weight distribution (Mw / Mn) of high cis BR is preferably 1.5 or more, and more preferably 2.0 or more. When Mw / Mn is less than 1.5, workability may be deteriorated. The Mw / Mn of BR is preferably 5.0 or less, and more preferably 4.0 or less. When Mw / Mn exceeds 5.0, the wear resistance tends to deteriorate. In addition, Mn and Mw of high cis BR in this specification are measured using GPC, and are converted by standard polystyrene.

  The content of the high cis BR in the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more from the viewpoint of exhibiting necessary wear resistance. Moreover, 90 mass% or less is preferable from a viewpoint of workability, as for content of high cis BR, 70 mass% or less is more preferable, and 60 mass% or less is further more preferable.

  As the rubber component, in addition to the high cis BR, natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR) other than high cis BR, styrene butadiene rubber (SBR), styrene Examples include isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene propylene diene rubber (EPDM), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). These rubber components may be used alone or in combination of two or more. Among these, diene rubbers such as NR, ENR, BR other than the high cis BR, and SBR are preferable because the required performance can be easily secured in each member of the tire. Furthermore, SBR is more preferable because it improves processability and grip.

  The rubber component other than the high cis BR may be one in which the main chain and / or terminal of the rubber is modified with a modifying agent, and a part thereof is a polyfunctional type, for example, a modifying agent such as tin tetrachloride or silicon tetrachloride. It may have a branched structure when used. Moreover, what is necessary is just to select suitably rubber components other than the said high cis BR, and its compounding quantity according to an application member.

  The SBR is not particularly limited, and examples thereof include solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), and modified SBR (modified S-SBR, modified E-SBR). Examples of the modified SBR include SBR having a terminal and / or main chain modified, modified SBR coupled with tin, a silicon compound, or the like (condensate, one having a branched structure, or the like).

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. When the styrene content of SBR is less than 5% by mass, sufficient grip performance and rubber strength may not be obtained. The styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 30% by mass or less. When the styrene content of SBR exceeds 60% by mass, there is a possibility that excellent fuel efficiency cannot be obtained. Incidentally, styrene content of the SBR herein is calculated by H ¹ -NMR measurement.

The vinyl content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. When the vinyl content of SBR is less than 10% by mass, sufficient grip performance and rubber strength may not be obtained. The vinyl content is preferably 65% by mass or less, more preferably 60% by mass or less, and further preferably 30% by mass or less. When the vinyl content of SBR exceeds 65% by mass, there is a possibility that excellent fuel efficiency cannot be obtained. Note that the vinyl content of the SBR in the present specification indicates that the amount of vinyl butadiene part, is calculated by H ¹ -NMR measurement.

  A rubber composition containing a white filler such as silica generally has low dispersibility of the filler, and it is difficult to obtain desired performance. However, according to the present invention, by containing hydroxystearic acid and / or a metal salt thereof, the interaction between the silica and the rubber component is increased, the dispersibility of the white filler is improved, fuel efficiency and abrasion resistance are improved. These properties can be compatible with each other, and good workability can be obtained, and the balance between these performances can be improved synergistically.

  The hydroxystearic acid and / or derivative thereof is preferably dihydroxystearic acid and / or a derivative thereof because the dispersibility of silica is further promoted, and a 1,2-substituted product is more preferred. As the derivatives, esters, amides, and metal salts are preferable because silica dispersibility is further promoted, and metal salts are more preferable. Among metal salts, zinc salts, magnesium salts, aluminum salts, calcium salts, and sodium salts are more preferable, zinc salts, magnesium salts, and aluminum salts are particularly preferable, and magnesium salts are most preferable.

  The content of hydroxystearic acid and / or its derivative with respect to 100 parts by mass of the rubber component is preferably 0.5 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass. When content is less than 0.5 mass part, there exists a tendency for the effect by containing hydroxystearic acid and / or its derivative (s) not to be exhibited. Moreover, when content exceeds 20 mass parts, there exists a tendency for workability to deteriorate by a viscosity fall.

  The rubber composition of the present invention preferably contains silica as a white filler because it improves the fuel efficiency of the tire. Silica is not particularly limited, and silica prepared by a wet method or a dry method can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of silica by the BET method is preferably 50 m ² / g or more, and more preferably 100 m ² / g or more. When N ₂ SA is less than 50 m ² / g, the rubber strength tends to decrease. The N ₂ SA of the silica is preferably 250 meters ² / g or less, more preferably 210 m ² / g. When N ₂ SA exceeds 250 m ² / g, processability tends to deteriorate. The N ₂ SA of silica can be measured by a method based on ASTM D3037-81.

  The content with respect to 100 parts by mass of the rubber component in the case of containing silica is preferably 5 parts by mass or more and more preferably 10 parts by mass or more because good fuel efficiency is obtained and a reinforcing effect is obtained. Moreover, 200 mass parts or less are preferable from the reason of ensuring low fuel consumption and workability, 180 mass parts or less are more preferable, and 150 mass parts or less are more preferable.

  The white filler other than silica is not particularly limited, and examples thereof include calcium carbonate, aluminum hydroxide, clay, mica, alumina, talc, and the like, which can be appropriately contained as necessary.

  When the rubber composition of the present invention contains silica, it is preferable to further contain a silane coupling agent. When the silane coupling agent is contained, the content with respect to 100 parts by mass of silica is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and further preferably 2.5 parts by mass or more. When the content is less than 0.5 parts by mass, it may be difficult to disperse silica well. The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. When the content exceeds 20 parts by mass, the silica dispersion effect is difficult to improve, the cost tends to increase unnecessarily, and the scorch time tends to be short, and the workability during kneading and extrusion tends to deteriorate.

  As the silane coupling agent, any silane coupling agent conventionally used in combination with silica 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-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-G Methoxysilylethyl) 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-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetra Sulfide, 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 methacrylate monosulfide, 3-trimethoxysilyl Sulfide systems such as propyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-octanoylthio-1-propyltriethoxy Mercapto type such as silane, vinyl type such as vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-amino Amino compounds such as nopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ- Glycidoxy compounds such as glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, etc. Examples include nitro-based, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane. Examples of the product names include Si69, Si75, Si363 (manufactured by EVONIK-DEGUSSA), NXT, NXT-LV, NXTULV, NXT-Z (manufactured by Momentive). These silane coupling agents may be used alone or in combination of two or more.

  The rubber composition of the present invention preferably contains carbon black because a good reinforcing effect can be obtained and the effect of preventing whitening can be enhanced. Examples of carbon black include GPF, FEF, HAF, ISAF, and SAF, but are not particularly limited.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably ^{80~280m 2 / g, 100~250m 2 /} g is more preferable. When N ₂ SA is less than 80 m ² / g, sufficient wet grip performance tends to be difficult to obtain, and wear resistance tends to decrease. Further, when N ₂ SA exceeds 280 m ² / g, the dispersibility is inferior and the wear resistance tends to be lowered. The N ₂ SA of carbon black is determined by the A method of JIS K6217.

  The content with respect to 100 parts by mass of the rubber component in the case of containing carbon black is preferably 1 to 150 parts by mass and more preferably 3 to 100 parts by mass because the mechanical strength of the rubber can be secured.

  In addition to the above materials, the rubber composition of the present invention is generally used in the tire industry such as oil, stearic acid, wax, resin, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators. The various materials currently used can be contained suitably.

  As a method for producing the rubber composition of the present invention, a known method can be used. For example, the above components are kneaded using a rubber kneader such as an open roll or a Banbury mixer, and then vulcanized. Can be manufactured.

  The tire member of the present invention is a tire member composed of the rubber composition, and is a rubber composition having excellent balance of wear resistance, workability and fuel efficiency, and therefore tires such as under treads and cap treads. It is preferable to use for a member.

  The tire of the present invention is produced by a usual method using the rubber composition. That is, the rubber composition is extruded in accordance with the shape of each tire member at an unvulcanized stage, molded by a normal method on a tire molding machine, and bonded together with other tire members, and an unvulcanized tire Form. The unvulcanized tire can be heated and pressurized in a vulcanizer to obtain the tire of the present invention.

  The tire of the present invention can be suitably used as a tire for passenger cars, tires for trucks and buses, tires for two-wheeled vehicles, competition tires, etc., since it can improve the wear resistance, processability and fuel efficiency in a balanced manner. It is suitably used as a tire.

  The present invention will be specifically described 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.
SBR: HPR850 manufactured by JSR Corporation (S-SBR, styrene content 28% by mass, vinyl content 56% by mass)
BR: BR730 manufactured by JSR Corporation (cis content: 95% by mass, Mooney viscosity: 55, Mw / Mn: 2.4)
Silica: Ultrasil VN3 (N ₂ SA: 175 m ² / g) manufactured by EVONIK-DEGUSSA
Carbon black: Dia Black I (ISAF carbon, average particle size 23 nm, N ₂ SA: 115 m ² / g) manufactured by Mitsubishi Chemical Corporation
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA
Stearic acid: Stearic acid “paulownia” manufactured by NOF Corporation
Hydroxystearic acid: 12-hydroxystearic acid aluminum stearate manufactured by Nitto Kasei Kogyo Co., Ltd .: 12 -hydroxyhydroxystearic acid aluminum magnesium stearate manufactured by Nitto Kasei Kogyo Co., Ltd .: 12 manufactured by Nitto Kasei Kogyo Co., Ltd. -Magnesium hydroxy stearate Zinc hydroxy stearate: 12 manufactured by Nitto Kasei Kogyo Co., Ltd.-Zinc hydroxy stearate Zinc oxide: Zinc oxide 2 types manufactured by Mitsui Kinzoku Mining Co., Ltd .: Ouchi Shinsei Chemical Co., Ltd. Nocrack 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine)
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

  In accordance with the formulation of Tables 1 and 2, using a 1.7L Banbury mixer manufactured by Kobe Steel Co., Ltd., chemicals other than sulfur and a vulcanization accelerator were filled so that the filling rate would be 58%, and 80 rpm And kneaded until reaching 140 ° C. to obtain a kneaded product. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is molded into a predetermined size and press vulcanized at 150 ° C. for 20 minutes to obtain a vulcanized rubber composition. Further, a vulcanized rubber of about 2 mm × 130 mm × 130 mm is obtained. A slab sheet was prepared. The following evaluation was performed about the obtained unvulcanized rubber composition and vulcanized rubber slab sheet. The results are shown in Tables 1 and 2.

<Workability test>
Based on JIS K6300-1, the Mooney viscosity (ML _{1 + 4} ) of the unvulcanized rubber composition was measured at 130 ° C., and the processability index of Comparative Example 1 was set to 100, and the processability was expressed by the following formula. did. The larger the index, the better the processability when unvulcanized. It should be noted that the workability index is 103 or more as a performance target index, and a processability index of 110 or more indicates particularly excellent workability.
(Processability index) = (Mooney viscosity of Comparative Example 1) / (Mooney viscosity of each formulation) × 100

<Viscoelasticity test>
The loss tangent (tan δ) of the vulcanized rubber slab sheet was measured under the conditions of a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho Co., Ltd. . The rolling resistance index of Comparative Example 1 was taken as 100, and the rolling resistance was indicated by an index according to the following formula. The larger the index, the lower the rolling resistance and the better the fuel economy. The rolling resistance index is 105 or more as a performance target index, and a rolling resistance index of 110 or more indicates particularly excellent fuel efficiency.
(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

<Abrasion resistance test>
The amount of wear of the vulcanized rubber composition was measured under the conditions of room temperature, applied load of 1.0 kgf, and slip rate of 30% using a Lambourn type wear tester. The wear resistance index of Comparative Example 1 was taken as 100, and the wear resistance was displayed as an index according to the following formula. The larger the index, the better the wear resistance. The wear index is 100 or more, and a performance index of 102 or more is particularly excellent in wear resistance.
(Abrasion resistance index) = (Abrasion amount of Comparative Example 1) / (Abrasion amount of each formulation) × 100

<Balance evaluation>
The balance of performance was evaluated based on the evaluation results obtained by the workability test, the viscoelasticity test, and the wear resistance test. The evaluation results are indicated by symbols according to the following criteria.
◎: All evaluation results satisfy the performance target index ○: Two evaluation results satisfy the performance target index ×: Two or more evaluation results do not satisfy the performance target index

  From the results shown in Tables 1 and 2, the rubber composition containing a butadiene rubber having a cis content of 90% by mass or more and a rubber composition containing hydroxystearic acid and / or a derivative thereof can be used for wear resistance and processing. It can be seen that an excellent rubber composition can be obtained with a good balance between properties and fuel efficiency.

Claims (7)

A rubber composition containing a butadiene rubber having a cis content of 90% by mass or more and 10% by mass or more of the rubber component, and a metal salt of hydroxystearic acid ,
A rubber composition in which the metal salt is a zinc salt, a magnesium salt, a calcium salt, or a sodium salt . The rubber composition according to claim 1, wherein the metal salt is a magnesium salt . Furthermore, the rubber composition of Claim 1 or 2 containing a silica. Furthermore, the rubber composition of any one of Claims 1-3 containing a stearic acid. Furthermore, the rubber composition of any one of Claims 1-4 containing a hydroxy stearic acid. The tire member comprised with the rubber composition of any one of Claims 1-5 . A tire provided with the tire member according to claim 6 .