JP2016108377A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition capable of enhancing processability, hardness and low fuel consumption performance and a pneumatic tire using the same.SOLUTION: There is provided a rubber composition by blending 100 pts.ass of a diene rubber, 0.5 to 20 pts.mass of a styrenated phenol compound mainly containing distyrenated phenol or tristyrenated phenol and 30 to 180 pts.mass of silica with average Tg of the diene rubber of -60°C to -20°C as well as blending a sulfur-containing silane coupling agent of 2 to 20 mass% based on silica. (A)(B)(C)(D)(R1)SiO, where A is a bivalent organic group containing a sulfide group, B is a C5 to 10 monovalent hydrocarbon group, C is a hydrolyzable group, D is an organic group containing a mercapto group, R1 is a C1 to 4 monovalent hydrocarbon group and 0<2a+b+c+d+e<4.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition and a pneumatic tire using the same, and more particularly to a rubber composition capable of improving processability, hardness and low fuel consumption performance and a pneumatic tire using the same. It is.

In general, a rubber composition for a tire is blended with a softening agent such as TDAE (Treated Distillate Aromatic Extract) in order to improve processability. However, when such a softening agent is blended, the hardness decreases, so that a large amount cannot be blended.
Further, if the amount of reinforcing filler such as carbon black is increased in order to suppress the decrease in hardness, the low fuel consumption performance of the tire is deteriorated. As described above, it has been considered difficult in the industry to improve the workability, hardness and fuel efficiency at the same time.

  Patent Document 1 listed below discloses a technique in which a rubber material is mixed with a deterioration inhibitor selected from methylene bis (alkyl sulfide) having a specific structure and a phenolic antioxidant. However, Patent Document 1 does not disclose or suggest the styrenated phenol compound of the present invention described below. In addition, there is no disclosure of a technical idea for simultaneously improving workability, hardness and fuel efficiency using a specific styrenated phenol compound.

Japanese Patent Publication No. 8-26178

  Accordingly, an object of the present invention is to provide a rubber composition capable of improving all of processability, hardness and fuel efficiency and a pneumatic tire using the same.

As a result of intensive studies, the present inventors have found that the above problem can be solved by blending a specific amount of a styrenated phenol compound, silica, and a specific silane coupling agent with a specific amount in a diene rubber. The present invention has been completed.
That is, the present invention is as follows.

1. For 100 parts by mass of diene rubber, 0.5-20 parts by mass of styrenated phenol compound mainly composed of distyrenated phenol or tristyrenated phenol and 30-180 parts by mass of silica are blended,
The average glass transition temperature (Tg) of the diene rubber is −60 ° C. to −20 ° C., and the sulfur-containing silane coupling agent represented by the following formula (1) is 2 to 20% by mass with respect to the silica. A rubber composition characterized by being compounded.
(A) _a (B) _b (C) _c (D) _d (R1) _e SiO _{(4-2a-bcde) / 2} (1)
(In the formula (1), A is a divalent organic group containing a sulfide group, B is a monovalent hydrocarbon group having 5 to 10 carbon atoms, C is a hydrolyzable group, and D is an organic containing a mercapto group. Group R1 represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, 0 ≦ a <1, 0 <b <1, 0 <c <3, 0 ≦ d <1, 0 ≦ e <2, and 0 <2a + b + c + d + e <4 is satisfied)
2. A pneumatic tire using the rubber composition described in 1 above.

  According to the present invention, since the specific styrenated phenol compound, silica, and the specific silane coupling agent are blended with the diene rubber in specific amounts, the workability, hardness, and fuel efficiency can all be improved. A rubber composition and a pneumatic tire using the rubber composition can be provided.

  Hereinafter, the present invention will be described in more detail.

(Diene rubber)
As the diene rubber used in the present invention, any diene rubber that can be blended in the rubber composition can be used, for example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR). Styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), ethylene-propylene-diene terpolymer (EPDM), and the like. These may be used alone or in combination of two or more. The molecular weight and microstructure are not particularly limited, and may be terminally modified with an amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl group or the like, or may be epoxidized.
The diene rubber used in the present invention needs to have an average glass transition temperature (average Tg) of −60 to −20 ° C. When the average Tg is less than −60 ° C., the hardness decreases. Conversely, if it exceeds -20 ° C, the wear resistance deteriorates. The average Tg is an average value of the glass transition temperature, and can be calculated as an average value from the glass transition temperature of each diene rubber and the blending ratio of each diene rubber.

(Styrenated phenol compound)
The styrenated phenol compound can be represented by the following formula.

  The styrenated phenol compound used in the present invention is mainly composed of distyrenated phenol in which n is 2 or tristyrenated phenol in which n is 3. The styrenated phenol compound used in the present invention can be produced by a known production method, and is also commercially available. Examples of commercially available products include SP-24 (distyrenated) manufactured by Sanko Co., Ltd. And phenol (mainly phenol), TSP (mainly tristyrenated phenol), and the like.

  Generally produced styrenated phenol compounds are monostyrenated phenols in which 1 mole of styrene is added to 1 mole of phenol (where n = 1); 2 moles of styrene are added to 1 mole of phenol. This is a mixture of distyrenated phenol (in the above formula, n = 2); tristyrenated phenol in which 3 mol of styrene is added to 1 mol of phenol (in the above formula, n = 3); and other components. In the present invention, among these styrenated phenol compounds, distyrenated phenol and tristyrenated phenol are used as main components. Since the styrenated phenol compound produced as described above is mainly a mixture of mono-, di-, and tri-isomers, the styrenated phenol compound used in the present invention can have some mono-isomers. Therefore, in the present invention, “having distyrenated phenol or tristyrenated phenol as a main component” means that distyrenated phenol or tristyrenated phenol is 50 mol% or more, preferably 60 mol% or more, more preferably It means that it occupies 65 mol% or more, and monostyrenated phenol and other components (for example, a styrenated phenol compound of a tetra-form or more) may be contained as other components.

  The styrene moiety in the above formula may be a styrene derivative. For example, α-methylstyrene, o-methylstyrene, 1,3-dimethylstyrene and the like can be mentioned.

(silica)
As the silica used in the present invention, any silica conventionally known to be used in rubber compositions such as dry silica, wet silica, colloidal silica and precipitated silica is used alone or in combination of two or more. it can.
In the present invention, from the viewpoint of the effect of the present invention is further improved, CTAB specific surface area of the silica (JIS K6217-3) is preferably from 70~240m ² / g, is 80~240m ² / g Is more preferable.

(Sulfur-containing silane coupling agent)
The sulfur-containing silane coupling agent used in the present invention is represented by the following formula (1).

(A) _a (B) _b (C) _c (D) _d (R1) _e SiO _{(4-2a-bcde) / 2} (1)

(In the formula (1), A is a divalent organic group containing a sulfide group, B is a monovalent hydrocarbon group having 5 to 10 carbon atoms, C is a hydrolyzable group, and D is an organic containing a mercapto group. Group R1 represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, 0 ≦ a <1, 0 <b <1, 0 <c <3, 0 ≦ d <1, 0 ≦ e <2, and 0 <2a + b + c + d + e <4 is satisfied)

  A sulfur-containing silane coupling agent (polysiloxane) represented by the formula (1) and a method for producing the same are disclosed in, for example, International Publication WO 2014/002750 pamphlet.

In the above formula (1), A represents a divalent organic group containing a sulfide group. Especially, it is preferable that it is group represented by following formula (12).
^{_{* - (CH 2) n -S}} x - (CH 2) n - * (12)
In said formula (12), n represents the integer of 1-10, and it is preferable that it is an integer of 2-4 especially.
In said formula (12), x represents the integer of 1-6, and it is preferable that it is an integer of 2-4 especially.
In the above formula (12), * indicates a bonding position.
Specific examples of the group represented by the formula (12), for ^{_{example, * -CH 2 -S 2 -CH 2}} - *, * -C 2 H 4 -S 2 -C 2 H 4 - *, * - _{C 3 H 6 -S 2 -C 3} H 6 - *, * -C 4 H 8 -S 2 -C 4 H 8 - *, * -CH 2 -S 4 -CH 2 - *, * -C 2 H _{4 -S 4 -C 2 H 4 -} *, * -C 3 H 6 -S 4 -C 3 H 6 - *, * -C 4 H 8 -S 4 -C 4 H 8 - * , and the like.

  In said formula (1), B represents a C1-C20 monovalent hydrocarbon group, As a specific example, a hexyl group, an octyl group, a decyl group etc. are mentioned, for example. B is preferably a monovalent hydrocarbon group having 5 to 10 carbon atoms.

In the above formula (1), C represents a hydrolyzable group, and specific examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, an alkenyloxy group, and the like. Especially, it is preferable that it is group represented by following formula (13).
^* -OR ² (13)
In the above formula (13), R ² is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group (aryl alkyl group) or an alkenyl group having 2 to 10 carbon atoms having from 6 to 10 carbon atoms In particular, an alkyl group having 1 to 5 carbon atoms is preferable. Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group, and an octadecyl group. Specific examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a tolyl group. Specific examples of the aralkyl group having 6 to 10 carbon atoms include a benzyl group and a phenylethyl group. Specific examples of the alkenyl group having 2 to 10 carbon atoms include a vinyl group, a propenyl group, and a pentenyl group.
In the above formula (13), * indicates a bonding position.

In said formula (1), D represents the organic group containing a mercapto group. Especially, it is preferable that it is group represented by following formula (14).
^{_{* - (CH 2) m -SH}} (14)
In said formula (14), m represents the integer of 1-10, and it is preferable that it is an integer of 1-5 especially.
In the above formula (14), * indicates a bonding position.
Specific examples of the group represented by the formula _{^{(14), * -CH 2 SH}} , * -C 2 H 4 SH, * -C 3 H 6 SH, * -C 4 H 8 SH, * -C 5 ^{_{H 10 SH, * -C 6 H}} 12 SH, * -C 7 H 14 SH, * -C 8 H 16 SH, * -C 9 H 18 SH, include * -C ₁₀ H ₂₀ SH.

  In said formula (1), R1 represents a C1-C4 monovalent hydrocarbon group.

  In the above formula (1), 0 ≦ a <1, 0 <b <1, 0 <c <3, 0 ≦ d <1, 0 ≦ e <2, and 0 <2a + b + c + d + e <4 are satisfied.

In the above formula (1), a is preferably 0 <a ≦ 0.50 because the effect of the present invention is improved.
In the above formula (1), b is preferably 0 <b and more preferably 0.10 ≦ b ≦ 0.89 because the effect of the present invention is improved.
In the above formula (1), c is preferably 1.2 ≦ c ≦ 2.0 because the effect of the present invention is improved.
In the above formula (1), d is preferably 0.1 ≦ d ≦ 0.8 because the effect of the present invention is improved.

The weight average molecular weight of the polysiloxane is preferably 500 to 2300, more preferably 600 to 1500, because the effect of the present invention is improved. The molecular weight of the polysiloxane in the present invention is determined in terms of polystyrene by gel permeation chromatography (GPC) using toluene as a solvent.
The mercapto equivalent of the polysiloxane in acetic acid / potassium iodide / potassium iodate addition-sodium thiosulfate solution titration is preferably 550 to 700 g / mol, and preferably 600 to 650 g from the viewpoint of excellent vulcanization reactivity. More preferably, it is / mol.

  The polysiloxane preferably has 2 to 50 siloxane units (—Si—O—) because the effect of the present invention is improved.

  In the skeleton of the polysiloxane, there are no metals other than silicon atoms (for example, Sn, Ti, Al).

  The manufacturing method of the said polysiloxane is well-known, For example, it can manufacture according to the method disclosed by international publication WO2014 / 002750 pamphlet.

(Rubber composition ratio)
In the rubber composition of the present invention, 0.5 to 20 parts by mass of a styrenated phenol compound mainly composed of distyrenated phenol or tristyrenated phenol and 30 to 180 parts by mass of silica with respect to 100 parts by mass of a diene rubber. The sulfur-containing silane coupling agent represented by the formula (1) is blended in an amount of 2 to 20% by mass with respect to the silica.
When the blending amount of the styrenated phenol compound is less than 1.0 part by mass, the blending amount is too small to achieve the effects of the present invention. Conversely, when it exceeds 20 mass parts, hardness will fall.
When the compounding amount of silica is less than 30 parts by mass, low fuel consumption performance cannot be obtained. On the other hand, when it exceeds 180 parts by mass, workability deteriorates.
When the compounding amount of the sulfur-containing silane coupling agent is less than 2% by mass with respect to the silica, the compounding amount is too small to achieve the effects of the present invention. Conversely, when it exceeds 20 mass%, scorch property will deteriorate.

More preferably, the blending amount of the styrenated phenol compound is 1 to 20 parts by weight with respect to 100 parts by weight of the diene rubber, and a particularly preferred blending amount of the styrenated phenol compound is with respect to 100 parts by weight of the diene rubber. 2 to 15 parts by mass.
A more preferable blending amount of the silica is 30 to 160 parts by mass with respect to 100 parts by mass of the diene rubber.
A more preferable amount of the sulfur-containing silane coupling agent is 2 to 18% by mass with respect to the silica.

(Other ingredients)
In the rubber composition of the present invention, in addition to the above-described components, a vulcanization or crosslinking agent; a vulcanization or crosslinking accelerator; various fillers such as zinc oxide, carbon black, clay, talc, calcium carbonate; Various additives generally blended in rubber compositions such as plasticizers can be blended, and these additives are kneaded by a general method to form a composition for vulcanization or crosslinking. Can be used. The blending amounts of these additives can be set to conventional general blending amounts as long as the object of the present invention is not violated.

  The rubber composition of the present invention is suitable for producing a pneumatic tire in accordance with a conventional method for producing a pneumatic tire, and is preferably applied to a tread, particularly a cap tread.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Standard example, Examples 1-2 and Comparative Examples 1-4
Sample Preparation In the formulation (parts by mass) shown in Table 1, the components except the vulcanization accelerator and sulfur were kneaded for 5 minutes with a 1.7 liter closed Banbury mixer, and then added with the vulcanization accelerator and sulfur. The rubber composition was obtained by kneading. Next, the obtained rubber composition was press vulcanized in a predetermined mold at 160 ° C. for 20 minutes to obtain a vulcanized rubber test piece, and an unvulcanized rubber composition and vulcanized rubber were tested by the following test method The physical properties of the test piece were measured.

Mooney viscosity: The viscosity of an unvulcanized rubber composition at 100 ° C. was measured according to JIS K6300. The results are shown as an index with the value of the standard example being 100. The smaller the index, the lower the viscosity and the better the workability.
Hardness (20 ° C.): Measured at 20 ° C. based on JIS K6253. The results are shown as an index with the value of the standard example being 100. The larger the index, the higher the hardness.
Low fuel consumption performance: Using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho, tan δ (60 ° C.) was measured under the conditions of a tensile deformation strain rate of 10 ± 2%, a frequency of 20 Hz, and a temperature of 60 ° C. The results are shown as an index with the value of the standard example being 100. The smaller the index, the lower the fuel consumption performance.
The results are shown in Table 1.

* 1: SBR (E581, manufactured by Asahi Kasei Co., Ltd., styrene content = 37 mass%, vinyl content = 42 mass%, glass transition temperature (Tg) = − 27 ° C., oil expansion amount = 37.5 mass relative to 100 mass parts of SBR (Table 1 shows actual SBR amount))
* 2: BR (Nipol BR1220 manufactured by Nippon Zeon Co., Ltd., Tg = −105 ° C.)
* 3: Carbon black (N339 manufactured by Cabot Japan Co., Ltd.)
* 4: Silica (ZEOSIL 1165MP manufactured by Rhodia, CTAB specific surface area = 159 m ² / g)
* 5: Styrenated phenol compound-1 (SP-F manufactured by Sanko Co., Ltd. Monostyrenated phenol 65 mol% or more, distyrenated phenol 32 mol% or less, tristyrenated phenol 1 mol% or less)
* 6: Styrenated phenol compound-2 (SP-24 manufactured by Sanko Co., Ltd. Monostyrenated phenol 0 mol%, distyrenated phenol 60 mol% or more, tristyrenated phenol 40 mol% or less)
* 7: Styrenated phenol compound-3 (TSP manufactured by Sanko Co., Ltd. Monostyrenated phenol 0 mol%, distyrenated phenol 30 mol% or less, tristyrenated phenol 65 mol% or more)
* 8: Silane coupling agent-1 (Si363 manufactured by Evonik Degussa Co., Ltd. Chemical formula = C ₁₃ H ₂₇ O (CH ₂ CH ₂ O) ₅ ] ₂ (CH ₂ CH ₂ O) Si (CH ₂ ) ₃ SH))
* 9: Silane coupling agent-2 (a compound satisfying the above formula (1) synthesized according to Synthesis Example 1 of International Publication WO2014 / 002750 pamphlet. Composition formula = (— C ₃ H ₆ —S ₄ —C ₃ H) _{6 -) 0.083 (-C 8 H} 17) 0.667 (-OC 2 H 5) 1.50 (-C 3 H 6 SH) 0.167 SiO 0.75, average molecular weight = 860)
* 10: Stearic acid (bead stearic acid YR manufactured by NOF Corporation)
* 11: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 12: Anti-aging agent (6PPD manufactured by Flexis)
* 13: Process oil (Extract No. 4 S manufactured by Showa Shell Sekiyu KK)
* 14: Vulcanization accelerator-1 (Noxeller CZ-G manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 15: Vulcanization accelerator-2 (Perkacit DPG manufactured by Flexis)
* 16: Sulfur (Tsurumi Chemical Co., Ltd. Jinhua Indian Oil Fine Powdered Sulfur, Sulfur content = 95.24% by mass)

As is clear from the results of Table 1 above, the rubber compositions obtained in Examples 1 and 2 have a specific amount of a specific styrenated phenol compound, silica and a specific silane coupling agent with respect to the diene rubber. Therefore, it can be seen that the processability, hardness and fuel efficiency are all improved compared to the conventional typical standard.
On the other hand, since the comparative example 1 uses the styrenated phenol compound which has monostyrenated phenol as a main component, hardness fell.
In Comparative Example 2, since the amount of silica was less than the lower limit specified in the present invention, low fuel consumption performance could not be obtained.
In Comparative Example 3, since the average Tg of the diene rubber was less than the lower limit specified in the present invention, the hardness decreased.
In Comparative Example 4, the hardness decreased because the blending amount of the styrenated phenol compound exceeded the upper limit defined in the present invention.

Claims (2)

For 100 parts by mass of diene rubber, 0.5-20 parts by mass of styrenated phenol compound mainly composed of distyrenated phenol or tristyrenated phenol and 30-180 parts by mass of silica are blended,
The average glass transition temperature (Tg) of the diene rubber is −60 ° C. to −20 ° C., and the sulfur-containing silane coupling agent represented by the following formula (1) is 2 to 20% by mass with respect to the silica. A rubber composition characterized by being compounded.
(A) _a (B) _b (C) _c (D) _d (R1) _e SiO _{(4-2a-bcde) / 2} (1)
(In the formula (1), A is a divalent organic group containing a sulfide group, B is a monovalent hydrocarbon group having 5 to 10 carbon atoms, C is a hydrolyzable group, and D is an organic containing a mercapto group. Group R1 represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, 0 ≦ a <1, 0 <b <1, 0 <c <3, 0 ≦ d <1, 0 ≦ e <2, and 0 <2a + b + c + d + e <4 is satisfied)   A pneumatic tire using the rubber composition according to claim 1.