JPH11130908A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. having excellent fuel-efficient property, wet characteristics, wear-resistance and rubber-burning resistance, by blending a diene rubber with a filler of a silica of a specified amt., a silane coupling agent, and a nonionic surfactant, each in a specified amt. SOLUTION: A compsn. comprises a blend of 100 pts.wt. of a diene rubber with 40-150 pts.wt. of a filler comprising a silica of 20-100 wt.%, pref. 30-100 wt.%, more pref. 50-100 wt.%, a silane coupling agent, pref. expressed by formula I and formula II, of 2 to less than 5 wt.% based on the blended silica amt., and a nonionic surfactant, pref. of a polyethylene glycol type or of a polyhydric alcohol type, of 2 to less than 10 wt.% based on the blended silica amt. In the formulae, Z is -Si(R<1> )2 R<2> , -SiR<1> (R<2> )2 or -Si(R<2> )3 ; R<1> is 1-4C alkyl, cyclohexyl or phenyl; R<2> is 1-8C alkoxy or 5-8C cycloalkoxy; R is 1-18C divalent hydrocarbyl and n is 2-8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition having excellent fuel efficiency (low rolling resistance), excellent wet performance such as grip performance on wet road surfaces, and excellent wear resistance, and also excellent rubber scorch resistance and fracture characteristics. About things.

[0002]

2. Description of the Related Art Conventionally, in a rubber composition for a tire, in particular, when silica is blended to achieve low fuel consumption (low rolling resistance), wet performance and abrasion resistance, a silane may be added to the rubber composition. Reinforcing properties are supplemented by adding a coupling agent.

In this case, the silane coupling agent must be chemically bonded to silanol groups on the silica surface during kneading. However, when kneading using an internal mixer such as a Banbury mixer, the reaction efficiency of the silane coupling agent is low, so a relatively large amount of 5 to 15% by weight of the silica is used. doing.

When a large amount of the silane coupling agent is blended, the amount of the silane coupling agent remaining unreacted also increases, and the rubber composition may be burned during kneading or the rubber composition may be destroyed after vulcanization. There is a problem that characteristics are deteriorated.

Accordingly, the present inventors have conducted intensive studies and as a result,
By compounding a nonionic surfactant, the amount of the silane coupling agent is minimized, and the silane coupling agent reacts completely to prevent rubber scorching during kneading and a rubber composition with excellent breaking characteristics I got something.

By the way, for example, Japanese Patent Application Laid-Open No. 8-53002
JP-A-8-73657 and JP-A-8-73657 disclose that a rubber composition containing silica is compounded with an activator to prevent delay in vulcanization and to aid dispersion of silica. The use of an activator different from the nonionic surfactant of the present invention and the use of a silane coupling agent has not been reduced, and the problem that the obtained rubber composition is inferior in rubber scorch resistance and breaking characteristics is solved. It has not been. Japanese Patent Application Laid-Open No. 9-111039 describes that a rubber composition containing silica is compounded with a nonionic surfactant for preventing static electricity.
Also in this technique, the amount of the silane coupling agent used is not reduced, and the rubber scoring resistance and the breaking properties of the obtained rubber composition are not improved.

[0007]

That is, an object of the present invention is to provide a rubber composition containing silica, which has a good balance of low fuel consumption (low rolling resistance), wet performance, abrasion resistance, and fracture characteristics. Another object of the present invention is to provide a rubber composition having excellent workability such as rubber burning resistance.

[0008]

According to the present invention, 40 to 150 parts by weight of a filler composed of 20 to 100% by weight of silica based on 100 parts by weight of a diene rubber, and 2 to 5% by weight of the silica compounding amount. % Of a silane coupling agent, and 2 to 10% by weight of a silica composition.

[0009] The silane coupling agent is

[0010]

Embedded image

(Where Z is -Si (R ¹ ) ₂ R ² , -Si
R ¹ (R ² ) ₂ or —Si (R ² ) ₃ (where R ¹ is an alkyl group having 1 to 4 carbon atoms, cyclohexyl group or phenyl group, and R ² is an alkoxy group having 1 to 8 carbon atoms or carbon number) 5-8 cycloalkoxy groups), and R is preferably a divalent hydrocarbon group having 1-18 carbon atoms, and n is an integer of 2-8.

The nonionic surfactant is preferably a polyethylene glycol type nonionic surfactant or a polyhydric alcohol type nonionic surfactant.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The diene rubber which can be used in the present invention may be any one which is generally used in the field of tires and the like. Representative examples of such diene rubbers include, for example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR) and the like, and these may be used alone or in any combination. Can be.

Next, silica is essential for the filler used in the present invention, but other fillers conventionally used in the field of, for example, tires such as carbon black may be used in combination.

There are no particular restrictions on the type and performance of silica and carbon black.

The amount of the filler in the present invention is 40 to 150 parts by weight based on 100 parts by weight of the diene rubber. This is because when the amount is less than 40 parts by weight, the wear resistance decreases, and when the amount exceeds 150 parts by weight, the workability decreases.

If the content of silica in the filler is less than 20% by weight, the rolling resistance increases, and the wet performance decreases. Therefore, in the present invention, the filler comprises 20 to 100% by weight of silica. The filler preferably contains 30 to 100% by weight of silica, more preferably 50 to 100% by weight of silica, from the viewpoint of satisfying both rolling resistance and wet performance.

The silane coupling agent used in the present invention may contain a sulfur atom from the viewpoint of binding to a rubber component.

[0019]

Embedded image

(Where Z is -Si (R ¹ ) ₂ R ² , -Si
R ¹ (R ² ) ₂ or —Si (R ² ) ₃ (where R ¹ is an alkyl group having 1 to 4 carbon atoms, cyclohexyl group or phenyl group, and R ² is an alkoxy group having 1 to 8 carbon atoms or carbon number) 5 to 8 cycloalkoxy groups), and R is preferably a divalent hydrocarbon group having 1 to 18 carbon atoms, and n is an integer of 2 to 8).

In the formula, Z is -Si (R ¹ ) ₂ R ² , -SiR ¹
(R ²⁾ ₂ or -Si (R ²⁾ are shown in _3, R ₁ is R ₂ methyl, ethyl, propyl, alkyl group having 1 to 4 carbon atoms such as butyl, cyclohexyl or phenyl
Is an alkoxy group having 1 to 8 carbon atoms such as methoxy, ethoxy and butoxy, or a cycloalkoxy group having 5 to 8 carbon atoms such as phenoxy and benzyloxy.

R is a divalent hydrocarbon group having 1 to 18 carbon atoms such as ethylene and propylene.

As the silane coupling agent represented by the formula (1), for example,

[0024]

Embedded image

And the like. Examples of commercially available products include Si69 (3,3'-bis (triethoxysilylpropyl) tetrasulfide) manufactured by Degussa.

The silane coupling agent represented by the formula (2) includes, for example,

[0027]

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And the like. Examples of commercially available products include TSL8380 manufactured by Toshiba Silicone Co., Ltd. and KBM803 (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

Among these, rubber scorch (scorch)
In view of this, it is preferable to use 3,3'-bis (triethoxysilylpropyl) tetrasulfide.

The amount of the silane coupling agent is as follows:
What is necessary is just 2 weight% or more and less than 5 weight% of the compounding quantity of the said silica. This is because if the amount is less than 2% by weight, the effect of dispersing the silica and the improvement of the wet performance by the silane coupling agent are insufficient, and if the amount is more than 5% by weight, the excess silane coupling agent is used. This causes the remaining rubber composition to deteriorate the processability and the breaking characteristics of the obtained rubber composition.

In the present invention, a nonionic surfactant is used from the viewpoint of compatibility between the rubber component and silica. The nonionic surfactant includes a polyethylene glycol type nonionic surfactant and a polyhydric alcohol type nonionic surfactant.

The polyethylene glycol type nonionic surfactant is a nonionic surfactant obtained by adding ethylene oxide as a hydrophilic group to a raw material of a hydrophobic group such as an alkylphenol or a higher fatty acid.

Examples of the polyethylene glycol type nonionic surfactant include higher alcohol ethylene oxide adducts such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene octyl phenyl ether, and polyoxyethylene nonyl phenyl ether. Fatty acid ethylene oxide adducts such as alkylphenol ethylene oxide adducts, polyethylene glycol monolaurate and polyethylene glycol monooleate, polyhydric alcohol fatty acid ester ethylene oxide adducts, polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether, etc. Higher alkylamine ethylene oxide adduct of polyoxyethylene coconut fatty acid monoeta Ruamaido, fatty acid amide ethylene oxide adducts, such as polyoxyethylene laurate monoethanol amide, fat ethylene oxide adducts, such as polyoxyethylene castor oil, polypropylene glycol ethylene oxide adducts and the like.

The polyhydric alcohol type nonionic surfactant is a nonionic surfactant obtained by bonding a hydrophobic group such as a higher fatty acid to a polyhydric alcohol such as glycerol or pentaerythritol. Examples of the polyhydric alcohol type nonionic surfactant include fatty acid esters of glycerol such as glycerol monostearate and glycerol monooleate, fatty acid esters of pentaerythritol such as pentaerythritol di-tallow fatty acid ester, and polyoxyethylene sorbitan monoester. Fatty acid esters of sorbitol and sorbitan such as laurate and polyoxyethylene sorbitan monostearate, fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines such as coconut fatty acid diethanolamide, and the like can be mentioned.

Of these, higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, and polyhydric alcohol fatty acid ester ethylene oxide adducts are preferred from the viewpoint of compatibility between the rubber component and silica.

The compounding amount of the nonionic surfactant in the present invention is 2% by weight or more and less than 10% by weight of the compounding amount of the silica. This is because if the amount is less than 2% by weight, the reactivity of the silane coupling agent, the dispersibility of silica, and the rolling resistance and wet performance of the obtained rubber composition are insufficiently improved. In such a case, the extraneous non-ionic surfactant causes the resulting rubber composition to have reduced fracture characteristics, abrasion resistance and durability. The compounding amount of the nonionic surfactant may be 2% by weight or more and less than 10% by weight of the compounding amount of the silica.

The rubber composition of the present invention contains, in addition to the above-mentioned components, a plasticizer, an antioxidant, a wax, a vulcanizing agent, a vulcanization accelerator and the like, which are used in ordinary rubber compositions. May be appropriately mixed within a range that does not impair the effect of the above.

Next, a method for producing the rubber composition of the present invention will be described. The rubber composition of the present invention is obtained by kneading the above components.

Conventionally, in a rubber composition containing silica, silica is agglomerated due to the presence of a silanol group on the silica surface to increase the viscosity of the rubber composition or to increase the polarity of the silanol group. Thus, a problem has been pointed out that vulcanization accelerators and the like are adsorbed on silica and vulcanization is delayed. The kneading temperature in the present invention is 150 to 170 ° C.
It is. In the present invention, the above problem is avoided by setting the kneading temperature within this range. When the temperature is lower than 150 ° C., the reaction between the silane coupling agent and silica becomes insufficient, and the rubber composition containing silica exhibits the characteristics such as the reduction of rolling resistance and the improvement of wet performance which the conventional rubber composition has. If the temperature is higher than 170 ° C., the crosslinking reaction proceeds in the rubber composition due to sulfur atoms contained in the silane coupling agent used in the present invention, and gelation (partial crosslinking) occurs, and the obtained rubber composition The rubber skin of the product is deteriorated, and the rubber physical properties of the rubber composition after vulcanization are reduced.
Further, the kneading temperature is preferably 150 to 170 ° C. from the viewpoint of the reaction between the silica and the silane coupling agent,
Furthermore, from the viewpoint of both the reaction and the burning of rubber,
Particularly preferred is 60 ° C.

The kneading time varies depending on the kneading machine to be used, but is preferably 2 to 20 minutes when the kneading temperature is 150 to 170 ° C. from the viewpoint of the reaction between the silica and the silane coupling agent. It is particularly preferable that the heating time is 2 to 10 minutes from the viewpoint of compatibility of rubber burning.

In the present invention, the rubber composition can be obtained using an internal mixer such as a Banbury mixer or a kneader.

Preferred combinations of the components of the rubber composition of the present invention and kneading conditions are shown below.

(Example) Diene rubber (styrene butadiene rubber) 100 parts by weight Filler 40 to 150 parts by weight Silica 8 to 150 parts by weight Carbon black 0 to 120 parts by weight Silane coupling agent 0.16 to 7.5 parts by weight (3,3′-bis (triethoxysilylpropyl) tetrasulfide) Nonionic surfactant 0.16 to 15 parts by weight (polyethylene glycol monolaurate, polyoxyethylene lauryl ether) Kneading temperature 150 to 170 ° C. Kneading time 2 ~ 20 minutes

Preferred combinations of the components of the rubber composition of the present invention and the kneading conditions are shown below.

Example 1 Diene rubber (SBR 1502) 100 parts by weight Filler 50 parts by weight Silica 50 parts by weight Carbon black 0 parts by weight Silane coupling agent (Si 69) 2 parts by weight Nonionic surfactant (Emanon 1112) 2 parts by weight Kneading temperature 150 to 170 ° C Kneading time 5 to 10 minutes (Example 2) Diene rubber (SBR 1502) 100 parts by weight Filler 60 parts by weight Silica 60 parts by weight Carbon black 60 parts by weight Silane coupling agent (Si 69) 2.4 parts by weight Nonionic surfactant (Emanon 1112) 4 parts by weight Kneading temperature 160 to 170 ° C. Kneading time 5 to 10 minutes (Example 3) 100 parts by weight of diene rubber (SBR 1502) 40 parts by weight of filler Silica 40 parts by weight Carbon black 0 parts by weight Silane coupling agent (Si 69) 15 parts by weight Nonionic surfactant (Emanon 1112) 2 parts by weight Kneading temperature 160-170 ° C Kneading time 5-10 minutes

The rubber composition of the present invention obtained as described above can be suitably used for, for example, treads and shoe soles of tires.

Hereinafter, the method for producing the rubber composition of the present invention will be described with reference to examples, but the present invention is not limited thereto.

[0048]

EXAMPLES In the examples of the present invention, the materials shown in Table 1 were used. In addition, diene rubber 1
1 part by weight of an antioxidant and vulcanization accelerator A per 100 parts by weight
One part by weight, 0.5 part by weight of a vulcanization accelerator B, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid and 1.5 parts by weight of sulfur were kneaded.

[0049]

[Table 1]

Examples 1-3 The components excluding sulfur at the kneading ratios shown in Table 2 were set to an initial set temperature of 100 ° C. using a BR type Banbury mixer.
After reaching 150 ° C., the mixture was kneaded for 5 minutes, sulfur was kneaded with an open roll, and then vulcanized at 175 ° C. for 15 minutes to obtain vulcanized rubber compositions 1 to 3 of the present invention.

Evaluation method The obtained vulcanized rubber composition was evaluated according to the following method. Table 2 shows the results. The following physical property values were evaluated based on Comparative Example 7.

Mooney test The Mooney viscosity and scorch time were measured according to JIS K6301. The lower the viscosity, the better the processability. The longer the scorch time, the better the workability. In the present invention, the Mooney viscosity ML (1 + 4) is 5
The scorch time may be 38 minutes or more.

Tensile test Elongation 100% and 3 according to JIS K 6301
00% tensile stresses M100 and M300 (MP
a), tensile strength _T B (MPa) and elongation at break E
_B (%) was measured. In the present invention, M100 is 2.
5MPa above, M300 is 9.6MPa or more, _{T B} is 2.5MPa or higher, _{E B} may be at 567% or more.

Viscoelasticity test Viscoelasticity spectrometer VES manufactured by Iwamoto Manufacturing Co., Ltd.
The loss coefficient (tan δ) was measured by setting the initial strain to 10%, the dynamic strain at a temperature of −10 ° C. to 0.5%, and the dynamic strain at a temperature of 70 ° C. to 2%. tan δ
(70 ° C.), the smaller the rolling resistance, the smaller the value of ta
The larger the value of nδ (−10 ° C.), the better the wet performance. In the present invention, tan δ (70 ° C.) is 0.17
It is sufficient that tan δ (−10 ° C.) is 0.24 or more.

Wear Test Using a Lambourn abrasion tester, the amount of wear was measured at a temperature of 20 ° C., a slip ratio of 20%, and a test time of 5 minutes. Then, the amount of wear in the case of Comparative Example 7 described later was set to 10
Assuming 0, the formula: (wear index) = (wear amount of rubber composition of Comparative Example 7) /
(Amount of wear of rubber composition to be measured) × 100 The larger the index, the better the wear resistance. In the present invention, the wear index may be 100 or more.

In the present invention, among the test items, tan δ (70 ° C.) to low fuel consumption, tan δ (−
Wet performance from 10 ° C.), the scorch time, resistance to rubber scorch resistance Mooney viscosity, T _B, it is possible to evaluate the fracture resistance from E _B and abrasion index.

Comparative Examples 1-2 Vulcanization was carried out in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to 0% by weight (Comparative Example 1) or 10% by weight (Comparative Example 2) of silica. The following comparative rubber compositions 1 and 2 were obtained and evaluated. Table 2 shows the results.

Example 4 Example 2 was repeated except that the type of the silane coupling agent was changed.
A vulcanized rubber composition 4 of the present invention was obtained in the same manner as described above, and was evaluated. Table 2 shows the results.

Example 5 A rubber composition 5 of the present invention after vulcanization was obtained and evaluated in the same manner as in Example 2 except that the type of the nonionic surfactant was changed. Table 2 shows the results.

Example 6 A rubber composition 6 of the present invention after vulcanization was obtained and evaluated in the same manner as in Example 2 except that the amount of the silane coupling agent was changed as shown in Table 2. . Table 2 shows the results.

[0061]

[Table 2]

According to Comparative Example 1, when the amount of the nonionic surfactant was less than 2% by weight of the amount of silica, tan
The value of δ (70 ° C.), that is, the rolling resistance increases,
It can be seen that the value of tan δ (−10 ° C.), that is, the wet performance is reduced. Further, it can be seen that the viscosity is high and the processability is poor.

Comparative Example 2 shows that when the amount of the nonionic surfactant is 10% by weight or more of the amount of the silica, the fracture characteristics, abrasion resistance and durability are reduced.

When the type of the silane coupling agent was changed (Example 4) and when the type of the nonionic surfactant was changed (Example 5), the breaking properties of the rubber composition of the present invention were also improved. It can be seen that the rubber scuff resistance is excellent.

Comparative Examples 3 to 5 Comparative rubber compositions 3 to 5 after vulcanization were obtained in the same manner as in Example 2 except that the amount of the silane coupling agent was changed as shown in Table 3, and the evaluation was performed. Done. Table 3 shows the results. Table 3 shows the results of Example 2 for comparison.

Examples 7 to 8 and Comparative Example 6 The same procedure as in Example 1 was carried out except that the mixing ratios shown in Table 3 were used, and the rubber compositions 7 to 8 of the present invention after vulcanization and the comparative compositions after vulcanization were used. Rubber compositions 6 to 7 were obtained and evaluated. Table 3 shows the results.

[0067]

[Table 3]

From Comparative Example 3, when the amount of the silane coupling agent is less than 2% by weight of the amount of silica, the viscosity is large and the processability is poor, and the rolling resistance (tan δ (70)
° C)) and wet performance (tan δ (-10
° C)) is low.

From Comparative Examples 4 and 5, it can be seen that when the amount of the silane coupling agent is 5% by weight or more of the amount of silica, the processability and the breaking characteristics are inferior.

From Example 7, it can be seen that the rubber composition of the present invention containing carbon black is also excellent in rubber burning resistance and breaking characteristics.

The rubber composition of Comparative Example 6 was used as a standard for evaluation of other rubber compositions.

Comparative Examples 9-13 Comparative rubber compositions 9-1 according to the compounding ratios shown in Table 4
3 and the same evaluation as in Example 1 was performed. Table 4 shows the results
Shown in

[0073]

[Table 4]

From Comparative Examples 8 and 9, it can be seen that when the amount of the filler is less than 40 parts by weight, the effect of the combined use of the nonionic surfactant is small.

From Comparative Examples 10 and 11, it can be seen that when the amount of the filler is large, when the amount of the filler exceeds 150 parts by weight, the effect of the combined use of the nonionic surfactant is not obtained.

From Comparative Examples 12 and 13, it can be seen that if the amount of silica is less than 20% by weight with respect to the amount of the filler, the combined use of the nonionic surfactant has no effect.

[0077]

According to the present invention, low rolling resistance, wet performance, abrasion resistance, and fracture characteristics are well-balanced and excellent.
Further, a rubber composition having excellent processability such as rubber burning resistance can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ikuyo Tamura 3-22-13-205 Kita-Aoki, Higashinada-ku, Kobe-shi, Hyogo (72) Inventor Noriko Yagi 5-11-16, Owada, Nishiyodogawa-ku, Osaka-shi

Claims (3)

[Claims] (1) 100 parts by weight of a diene rubber,
Filler consisting of 0 to 100% by weight of silica 40 to 150
A rubber composition comprising, by weight, a silane coupling agent in an amount of 2% by weight or more and less than 5% by weight based on the silica content, and a nonionic surfactant in an amount of 2% by weight or more and less than 10% by weight based on the silica content. 2. The method according to claim 1, wherein the silane coupling agent is (In the formula, Z is -Si (R ¹ ) ₂ R ² , -SiR ¹ (R ² ) ₂ or -Si (R ² ) ₃ (where R ¹ is an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group or A phenyl group, R ² is an alkoxy group having 1 to 8 carbon atoms or a cycloalkoxy group having 5 to 8 carbon atoms), R is a divalent hydrocarbon group having 1 to 18 carbon atoms, and n is an integer of 2 to 8) The rubber composition according to claim 1, which is indicated. 3. The rubber composition according to claim 1, wherein the nonionic surfactant is a polyethylene glycol type nonionic surfactant or a polyhydric alcohol type nonionic surfactant.