JP5321751B2 - Rubber composition for tire, pneumatic tire, and method for producing rubber composition for tire - Google Patents

Description

  The present invention relates to a tire rubber composition, a pneumatic tire, and a method for producing a tire rubber composition.

  Pneumatic tires are required to be products that are friendly to the global environment, and are particularly required to have excellent fuel efficiency. At the same time, the basic characteristics of the tire, such as grip performance represented by acceleration performance and braking performance, and wear resistance that affects tire life, must be equal to or higher than those of conventional tires.

  However, low rolling resistance and grip performance are contradictory properties, and it is generally difficult to achieve both at a high level. Furthermore, when trying to optimize both low rolling resistance and grip performance, wear resistance is reduced. There was a problem of getting worse.

  Patent Document 1 proposes to improve wear resistance and grip performance by a rubber composition containing solution-polymerized styrene butadiene rubber, polybutadiene rubber, resin, carbon black and silica having specific structural characteristics. However, this rubber composition has an insufficient effect of reducing rolling resistance, and further improvement is required for wear resistance and grip performance, and there is room for improvement.

JP 2006-249403 A

  An object of the present invention is to provide a rubber composition for a tire, a pneumatic tire, and a method for producing a tire rubber composition, in which low rolling resistance, grip performance and wear resistance are improved to a conventional level or higher. It is in.

The rubber composition for a tire of the present invention that achieves the above object comprises 100 parts by weight of a diene rubber containing 70 to 95% by weight of a solution-polymerized styrene butadiene rubber and 5 to 20% by weight of a butadiene rubber, and 1 to 1 of an aromatic modified terpene resin. A rubber composition containing 20 parts by weight and 45 to 100 parts by weight of silica having a BET specific surface area of 100 to 200 m ² / g,
The aromatic compound constituting the aromatic modified terpene resin is at least one selected from styrene, α-methylstyrene, vinyltoluene,
The solution-polymerized styrene-butadiene rubber has a styrene unit content (S) of 35 to 45% by weight, a vinyl unit content (V) of 35% by weight or more, the styrene unit content (S) and a vinyl unit content (V ) Ratio (V / S) is 0.75 or more and 2.00 or less,
The rubber composition has a ratio of tan δ at 0 ° C. to tan δ at 60 ° C. (tan δ (0 ° C.) / Tan δ (60 ° C.)) of 2.50 to 2.78 .
The pneumatic tire of the present invention includes a tread portion made of the tire rubber composition.
The method for producing the tire rubber composition of the present invention comprises:
100 parts by weight of a diene rubber containing 70 to 95% by weight of solution-polymerized styrene butadiene rubber and 5 to 20% by weight of butadiene rubber, 1 to 20 parts by weight of an aromatic modified terpene resin, and a BET specific surface area of 100 to 200 m ² / g. A step of preparing 45 to 100 parts by weight of silica,
A step of kneading the diene rubber, the aromatic modified terpene resin, and the silica at 149 to 160 ° C. except for a vulcanizing compound containing sulfur and a vulcanization accelerator . A manufacturing method comprising:
The aromatic compound constituting the aromatic modified terpene resin is at least one selected from styrene, α-methylstyrene, vinyltoluene,
The solution-polymerized styrene butadiene rubber has a styrene unit content (S) of 35 to 45% by weight, a vinyl unit content (V) of 35% by weight or more, and a vinyl unit content (V) relative to the styrene unit content (S). ) Ratio (V / S) is 0.75 or more and 2.00 or less,
The rubber composition has a ratio of tan δ at 0 ° C. to tan δ at 60 ° C. (tan δ (0 ° C.) / Tan δ (60 ° C.)) of 2.50 to 2.78 .

  When used in tires, the rubber composition for tires of the present invention can improve the low rolling resistance, grip performance and wear resistance to the conventional level or more.

  The pneumatic tire using the rubber composition for tires of the present invention can improve the low rolling resistance, grip performance and wear resistance from the conventional level.

  In the rubber composition for tires of the present invention, the rubber component is composed of a diene rubber, 70 to 95% by weight of solution-polymerized styrene butadiene rubber (hereinafter referred to as “S-SBR”), and 5 to 20% by weight of butadiene rubber. % Must be contained. The diene rubber may contain other diene rubbers other than S-SBR and butadiene rubber. Examples of other diene rubbers include natural rubber, isoprene rubber, emulsion-polymerized styrene butadiene rubber, butyl rubber, and propylene-ethylene-diene rubber. Of these, natural rubber and isoprene rubber are preferable. The blending amount of the other diene rubber is 0 to 25% by weight, preferably 0 to 20% by weight, in 100% by weight of the diene rubber.

  The content of S-SBR is 70 to 95% by weight, preferably 72 to 95% by weight, and more preferably 75 to 80% by weight in 100% by weight of the diene rubber. When the content of S-SBR is less than 70% by weight, the effect of improving grip performance is not sufficient. Moreover, when content of S-SBR exceeds 95 weight%, abrasion resistance will deteriorate.

  In the rubber composition of the present invention, S-SBR has a styrene unit content of 35 to 45% by weight, preferably 35 to 44% by weight, and more preferably 40 to 41% by weight. When the styrene unit content of S-SBR is less than 35% by weight, grip performance is not improved to a sufficient level. On the other hand, if the styrene unit content of S-SBR exceeds 45% by weight, the mixing processability is deteriorated. In addition, styrene unit content of S-SBR shall be measured by infrared spectroscopy (Hampton method).

  The vinyl unit content of S-SBR is 35% by weight or more, preferably 36 to 80% by weight, more preferably 38 to 71% by weight. When the vinyl unit content of S-SBR is less than 35% by weight, the dispersibility of silica is deteriorated, resulting in deterioration of wear resistance. The lower limit of the vinyl unit content is determined so that the ratio (V / S) described later is 0.75 to 2.0. The vinyl unit content of S-SBR is measured by infrared spectroscopic analysis (Hampton method).

  In the present invention, the ratio (V / S) of styrene unit content (S) and vinyl unit content (V) of S-SBR is 0.75 to 2.00, preferably 0.77 to 2.00, Preferably it is 0.93-1.00. When the ratio (V / S) is less than 0.75, good grip performance cannot be obtained. On the other hand, if the ratio (V / S) exceeds 2.00, the rubber's fracture property (particularly, elongation at break) deteriorates, and wear resistance deteriorates.

  The rubber composition of the present invention contains 5 to 20% by weight, preferably 7 to 20% by weight, more preferably 10 to 20% by weight of butadiene rubber in 100% by weight of the diene rubber. When the content of butadiene rubber is less than 5% by weight, the wear resistance is deteriorated. If the content of butadiene rubber exceeds 20% by weight, it is difficult to improve grip performance.

  In the present invention, the balance between low rolling resistance and grip performance can be improved by blending the aromatic modified terpene resin. The aromatic modified terpene resin is obtained by copolymerizing a terpene and an aromatic compound. The aromatic compound is at least one selected from styrene, α-methylstyrene, and vinyl toluene. Examples of terpenes include α-pinene, β-pinene, dipentene, limonene, camphene and the like. Commercially available products such as YS resin TO-125, TO-115, TO-105, TO-105, TO-85 and TR-105 manufactured by Yasuhara Chemical Co., Ltd. can be used as the aromatic modified terpene resin.

  The compounding amount of the aromatic modified terpene resin is 1 to 20 parts by weight, preferably 1 to 18 parts by weight, more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the diene rubber. When the blending amount of the aromatic modified terpene resin is less than 1 part by weight, the balance between low rolling resistance and grip performance cannot be sufficiently increased. Moreover, when the compounding quantity of aromatic modified terpene resin exceeds 20 weight part, rolling resistance will deteriorate on the contrary. In addition, wear resistance is reduced.

The rubber composition for tires of the present invention is blended with silica having specific particle properties. By blending silica, the exothermic property of the rubber composition is suppressed, rolling resistance when used in a tire is reduced, and wet grip performance is improved. BET specific surface area of silica is 100 to 200 m ² / g, preferably in 110~200m ² / g. When the BET specific surface area of silica is less than 100 m ² / g, the rubber composition is insufficiently reinforced and wear resistance is insufficient, and grip performance is also deteriorated. On the other hand, when the BET specific surface area of silica exceeds 200 m ² / g, the dispersibility of the silica with respect to the diene rubber decreases, so that the wear resistance deteriorates and the rolling resistance increases. In addition, the BET specific surface area of a silica is calculated | required based on ASTMD1993-03.

  In the present invention, the amount of silica is 45 to 100 parts by weight, preferably 50 to 100 parts by weight, per 100 parts by weight of the diene rubber. If the blending amount of silica is less than 45 parts by weight, the effect of improving grip performance cannot be obtained sufficiently. When the amount of silica exceeds 100 parts by weight, the rubber viscosity increases and the silica dispersion deteriorates, so that the wear resistance deteriorates.

  The silica used by this invention should just be a silica which has the characteristic mentioned above, and can use a commercially available thing suitably. Moreover, you may manufacture by the normal method so that it may have the characteristic mentioned above. As the type of silica, for example, wet method silica, dry method silica, or surface-treated silica can be used.

  In the rubber composition of the present invention, it is preferable to blend a silane coupling agent together with silica, so that the dispersibility of silica can be improved and the reinforcement to the diene rubber can be further enhanced. The silane coupling agent is preferably added in an amount of 3 to 15% by weight, more preferably 5 to 12% by weight, based on the amount of silica. When the silane coupling agent is less than 3% by weight of the silica weight, the effect of improving the dispersibility of silica cannot be sufficiently obtained. On the other hand, when the silane coupling agent exceeds 15% by weight, the silane coupling agents are condensed with each other, and a desired effect cannot be obtained.

  Although it does not restrict | limit especially as a silane coupling agent, A sulfur containing silane coupling agent is preferable, for example, bis- (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide. , 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, and the like.

  The rubber composition for tires of the present invention can increase the strength of rubber by blending other fillers than silica. Examples of other fillers include carbon black, clay, mica, talc, calcium carbonate, aluminum hydroxide, and aluminum oxide. Of these, carbon black is preferred. By blending carbon black, the rubber hardness can be increased to ensure grip performance, and the wear resistance of the rubber composition can be improved.

  In the tire rubber composition of the present invention, the ratio of tan δ at 0 ° C. to tan δ at 60 ° C. (tan δ (0 ° C.) / Tan δ (60 ° C.)) is 2.50 or more, preferably 2.51 or more. is necessary. If the ratio (tan δ (0 ° C.) / Tan δ (60 ° C.)) is less than 2.50, the balance of the three performances of low rolling resistance, grip performance and wear resistance cannot be improved. Note that the ratio (tan δ (0 ° C.) / Tan δ (60 ° C.)) is never infinitely large because tan δ (60 ° C.) never becomes 0. For example, the ratio (tan δ (0 ° C.) / Tan δ (60 ° C.)) exceeds 20 even if the virtual rubber is tan δ (0 ° C.) = 1.00 and tan δ (60 ° C.) = 0.05. There is no. For a rubber composition having a ratio (tan δ (0 ° C.) / Tan δ (60 ° C.)) of 2.50 or more, adjust the particle size and blending amount of silica, or adjust the kneading conditions of the rubber composition. Can also be manufactured. As the kneading conditions of the rubber composition, after kneading at a relatively high temperature when kneading the rubber composition excluding vulcanizing compounding agents such as sulfur and vulcanization accelerator from the final composition, and after cooling A kneading / mixing method in which a vulcanizing compounding agent is added and mixed may be mentioned. The temperature when kneading the rubber composition excluding the vulcanizing compounding agent is preferably 149 to 160 ° C, more preferably 150 to 160 ° C.

  In addition to the fillers described above, tire rubber compositions generally used for tire rubber compositions such as vulcanization or crosslinking agents, vulcanization accelerators, anti-aging agents, plasticizers, processing aids, etc. These additives can be blended, and such additives can be kneaded by a general method, blended into a rubber composition, and used for vulcanization or crosslinking. As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used. Such a rubber composition can be produced by mixing each of the above components using a known rubber kneading machine, for example, a Banbury mixer, a kneader, a roll or the like.

  The rubber composition for tires of the present invention can be suitably used as a tread rubber for pneumatic tires, particularly pneumatic tires. A pneumatic tire using this rubber composition has a low rolling resistance and an excellent fuel economy performance, an excellent wear resistance and a long tire life, and an excellent grip performance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  Using the compounding agents shown in Table 4 as a common compounding, 25 types of tire rubber compositions (Examples 1 to 11, Comparative Examples 1 to 5 and 8 to 16) having the compositions shown in Tables 1 to 3 were added to sulfur, The other common ingredients except the sulfur accelerator are kneaded for 5 minutes with a 1.8 L closed mixer, air-cooled to the master batch released at 150 ° C, sulfur and vulcanization accelerator are added and kneaded with an open roll. It was prepared by doing. In addition, the rubber compositions for tires of Comparative Examples 6 and 7 were prepared by kneading the components excluding sulfur and vulcanization accelerator for 5 minutes with a 1.8 L closed mixer and releasing them at a temperature of 140 ° C. , Sulfur and a vulcanization accelerator were added and kneaded with an open roll.

  In Tables 1 to 3, since S-SBR1 to 4 and E-SBR contain 37.5 parts by weight of oil-extended oil, each of the amounts excluding oil-extended oil as well as the actual amount in the column of amount The SBR net compounding amount is shown in parentheses. Moreover, the quantity of the compounding agent described in Table 4 was shown in the weight part with respect to 100 weight part (net rubber amount) of the diene rubber described in Tables 1-3.

  The 27 types of tire rubber compositions (Examples 1 to 11 and Comparative Examples 1 to 16) thus obtained were press vulcanized at 160 ° C. for 20 minutes in a mold having a predetermined shape to produce a vulcanized rubber sample. Then, tan δ (0 ° C.) and tan δ (60 ° C.) and wear resistance were measured by the method described below.

(Grip performance: tan δ (0 ° C.), low rolling resistance: tan δ (60 ° C.))
Using the viscoelasticity spectrometer made by Toyo Seiki Seisakusho, tan δ (0 ° C.) and tan δ (60 ° C.) of the obtained vulcanized rubber sample were subjected to the conditions of initial strain 10%, amplitude ± 2%, and frequency 20 Hz. The temperature was measured at 0 ° C. and 60 ° C. The obtained results are shown in the columns of “Grip performance” and “Rolling resistance” in Tables 1 to 3 with the index of Comparative Example 1 being 100. As the index of grip performance is larger, tan δ (0 ° C.) is larger, which means that grip performance is superior. Also, the smaller the rolling resistance index, the smaller the tan δ (60 ° C.), the lower the heat generation, the lower the rolling resistance when made into a tire, and the better the fuel efficiency. The ratio of tan δ (0 ° C.) to tan δ (60 ° C.) (tan δ (0 ° C.) / Tan δ (60 ° C.)) is shown in the column of “0 ° C. tan δ / 60 ° C. tan δ” in Tables 1-3.

(Abrasion resistance)
The amount of wear of the obtained test piece was measured in accordance with JIS K6264-2 using a Lambourne abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) at a temperature of 20 ° C., a load of 15 N, a slip rate of 50%, and a time of 10 minutes. Was measured. The obtained results are shown in the column of “Abrasion resistance” in Tables 1 to 3 as an index where the reciprocal of the value of Comparative Example 1 is 100. The larger the index, the smaller the amount of wear and the better the wear resistance.

In addition, the kind of raw material used in Tables 1-3 is shown below.
S-SBR1: Solution-polymerized styrene butadiene rubber, Toughden 1834 manufactured by Asahi Kasei Chemicals Co., Ltd., styrene unit content (S) 19% by weight, vinyl unit content (V) 10% by weight, ratio (V / S) 0 .53, Oil-extended product containing 37.5 parts by weight of oil with respect to 100 parts by weight of rubber component. S-SBR2: Solution-polymerized styrene butadiene rubber, HP755B manufactured by JSR, 41% by weight of styrene unit content (S), vinyl Oil-extended product containing unit content (V) of 41% by weight, ratio (V / S) of 1.00, and 37.5 parts by weight of oil to 100 parts by weight of rubber component. S-SBR3: solution polymerized styrene butadiene rubber , LANXESS BUNA VSL 2438-2 HM, styrene unit content (S) 41 wt%, vinyl unit content (V) 38 wt%, ratio (V / S) 0. 3. Oil-extended product containing 37.5 parts by weight of oil with respect to 100 parts by weight of rubber component. S-SBR4: Solution-polymerized styrene butadiene rubber, Nipol NS460 manufactured by Nippon Zeon Co., Ltd., 27 weight of styrene unit content (S) %, Vinyl unit content (V) is 71% by weight, ratio (V / S) is 2.63, and the oil component contains 37.5 parts by weight of oil with respect to 100 parts by weight of the rubber component. Styrene butadiene rubber, Nipol 1739 manufactured by Nippon Zeon Co., Ltd., styrene unit content (S) 40% by weight, vinyl unit content (V) 13% by weight, ratio (V / S) 0.33, rubber component 100% Oil containing 37.5 parts by weight of oil with respect to parts. BR: Butadiene rubber, Nipol BR1220 manufactured by Nippon Zeon Co., Ltd.
・ NR: Natural rubber, SIR20 manufactured by KIRANA SAPTA
・ Carbon black: Toast carbon company's seast 7HM
Silica 1: ULTRASIL VN3GR manufactured by Evonik Degussa, BET specific surface area of 171 m ² / g
Silica 2: Zeosil 215GR manufactured by Rhodia, BET specific surface area is 220 m ² / g
Silica 3: Zeosil 1115MP manufactured by Rhodia, BET specific surface area of 95 m ² / g
Coupling agent: Sulfur-containing silane coupling agent, Si69 manufactured by Evonik Degussa
Terpene resin 1: aromatic modified (styrene modified) terpene resin, YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd.
-Terpene resin 2: Unmodified terpene resin, YS resin PX200 manufactured by Yasuhara Chemical Co., Ltd.
Terpene resin 3: Phenol-modified terpene resin, YS Polystar T-130 manufactured by Yasuhara Chemical
Aroma oil: Showa Shell Sekiyu Extract No. 4 S

The types of raw materials used in Table 4 are shown below.
・ Zinc oxide: 3 types of zinc oxide manufactured by Shodo Chemical Co., Ltd. ・ Stearic acid: Beads stearic acid YR manufactured by NOF Corporation
Anti-aging agent: Santoflex 6PPD manufactured by Flexis
・ Wax: Sunnock made by Ouchi Shinsei Chemical Co., Ltd. ・ Sulfur: Fine powder sulfur with Jinhua seal oil made by Tsurumi Chemical Co., Ltd. ・ Vulcanization accelerator: CBS vulcanization accelerator, Noxeller CZ-G made by Ouchi Shinsei Chemical Co., Ltd.

  As apparent from Tables 1 to 3, the rubber compositions for tires of Examples 1 to 12 maintain and improve the grip performance (tan δ at 0 ° C.), the low rolling resistance (tan δ at 60 ° C.), and the wear resistance. It was confirmed.

In the rubber composition of Comparative Example 2, since the amount of silica 1 is less than 45 parts by weight, the effect of improving the grip performance cannot be sufficiently obtained. In the rubber composition of Comparative Example 3, since the blending amount of the terpene resin 1 is less than 1 part by weight, the balance between the low rolling resistance and the grip performance cannot be sufficiently increased. In the rubber composition of Comparative Example 4, since the blending amount of butadiene rubber exceeds 20% by weight, it is difficult to improve grip performance.
The rubber compositions of Comparative Examples 6 and 7 have 0 ° C. tan δ / 60 ° C. tan δ of less than 2.50 depending on the kneading conditions, and therefore improved by balancing the three performances of low rolling resistance, grip performance, and wear resistance. Can not do it.

  As is apparent from Table 3, the rubber composition of Comparative Example 8 cannot improve rolling resistance and wear resistance because E-SBR is blended in place of S-SBR. Since the rubber composition of Comparative Example 9 has an S-SBR4 ratio (V / S) exceeding 2.00, the wear resistance is deteriorated.

The rubber composition of Comparative Example 10 cannot improve the grip performance because the amount of S-SBR2 is less than 70 parts by weight. In the rubber composition of Comparative Example 11, since the BET specific surface area of silica 3 is less than 100, the wear resistance is insufficient and the grip performance is also lowered. In the rubber composition of Comparative Example 12, since the BET specific surface area of silica 2 exceeds 200 m ² / g, the rolling resistance is deteriorated.

  Since the rubber composition of Comparative Example 13 was blended with terpene resin 2 (unmodified terpene resin) instead of terpene resin 1 (aromatic modified terpene resin), the grip performance could not be improved and the wear resistance was also improved. Getting worse. Although the rubber composition of Comparative Example 14 was blended with terpene resin 3 (phenol-modified terpene resin) instead of terpene resin 1 (aromatic-modified terpene resin), the grip performance was greatly improved, but rolling resistance and abrasion resistance were improved. Gets worse.

  In the rubber composition of Comparative Example 15, since the blending amount of the terpene resin 1 exceeds 20 parts by weight, the rolling resistance is deteriorated. Also, the wear resistance cannot be improved. In the rubber composition of Comparative Example 16, since the compounding amount of silica 1 exceeds 100 parts by weight, the wear resistance is deteriorated.

Claims (4)

100 parts by weight of a diene rubber containing 70 to 95% by weight of solution-polymerized styrene butadiene rubber and 5 to 20% by weight of butadiene rubber, 1 to 20 parts by weight of an aromatic modified terpene resin, and a BET specific surface area of 100 to 200 m ² / g. A rubber composition containing 45 to 100 parts by weight of silica,
The aromatic compound constituting the aromatic modified terpene resin is at least one selected from styrene, α-methylstyrene, vinyltoluene,
The solution-polymerized styrene butadiene rubber has a styrene unit content (S) of 35 to 45% by weight, a vinyl unit content (V) of 35% by weight or more, and a vinyl unit content (V) relative to the styrene unit content (S). ) Ratio (V / S) is 0.75 or more and 2.00 or less,
A rubber composition for tires, wherein a ratio of tan δ at 0 ° C. to tan δ at 60 ° C. (tan δ (0 ° C.) / Tan δ (60 ° C.)) of the rubber composition is 2.50 to 2.78 .   A pneumatic tire provided with a tread portion comprising the rubber composition for a tire according to claim 1. 100 parts by weight of a diene rubber containing 70 to 95% by weight of solution-polymerized styrene butadiene rubber and 5 to 20% by weight of butadiene rubber, 1 to 20 parts by weight of an aromatic modified terpene resin, and a BET specific surface area of 100 to 200 m ² / g. A step of preparing 45 to 100 parts by weight of silica,
A step of kneading the diene rubber, the aromatic modified terpene resin, and the silica at 149 to 160 ° C. except for a vulcanizing compound containing sulfur and a vulcanization accelerator . A manufacturing method comprising:
The aromatic compound constituting the aromatic modified terpene resin is at least one selected from styrene, α-methylstyrene, vinyltoluene,
The solution-polymerized styrene butadiene rubber has a styrene unit content (S) of 35 to 45% by weight, a vinyl unit content (V) of 35% by weight or more, and a vinyl unit content (V) relative to the styrene unit content (S). ) Ratio (V / S) is 0.75 or more and 2.00 or less,
A ratio of tan δ at 0 ° C. to tan δ at 60 ° C. (tan δ (0 ° C.) / Tan δ (60 ° C.)) of the rubber composition is from 2.50 to 2.78 . Manufacturing method.   The manufacturing method of the rubber composition for tires of Claim 3 which further includes the process of cooling the kneaded material obtained by the said kneading | mixing after the said kneading | mixing process and adding the said vulcanization | cure type compounding agent after cooling.