JPH11263882A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition having a balanced, high rolling resistance, wet performance and wear resistance. SOLUTION: This composition is obtained by (a) mixing a vulcanizable polymer, silica and at least one of silane coupling agents of formula I: Z-R-Sn -R-Z, formula II: Z-R-S-H, formula III: Z-R-NH2 , formula IV Z-CH=CH2 or formula V: Z-R-Cl [wherein R is a divalent hydrocarbon group with a carbon number of 1 to 18; n is an integer of 2 to 8; and Z is -Si(R<1> )2 R<2> , -SiR<1> (R<2> ), or -Si(R<2> )3 (wherein R<1> is a 1-4C alkyl group, a cyclohexyl group or a phenyl group; and R<1> is a 1-8C alkoxy group or a 5-8C cycloalkoxy group)] at a temperature lower than 130 deg.C for from 30 sec to 30 min, (b) mixing them at 130 to 180 deg.C for 1 to 20 min and (c) adding a vulcanizing agent and a vulcanization accelerator and mixing them at a vulcanization temperature or lower for 1 to 20 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition containing silica.

[0002]

2. Description of the Related Art Conventionally, particularly in the field of tires, silica has been used in place of carbon black as a reinforcing material to meet market demands for wear resistance and low fuel consumption. For the above and performance reasons, a silane coupling agent is also compounded. In this case, since the rubber composition after vulcanization is cured, the silane coupling agent and silica need to react during processing.

[0003] Thus, for example, diethylene glycol and fatty acids (Rubber Industry Handbook (Fourth Edition)), metal salts of carboxylic acids (Tire Technology International (Tire Technology International))
Technology International), 1995), dithiopropionic acid (JP-A-9-176381), modified silicone oil (JP-A-9-111444), calcium carbonate (JP-A-9-150606), inorganic filler ( International Patent Application No. 95-31888 pamphlet, Japanese Patent Application Laid-Open No. 8-59894), a method of adding sodium thiosulfate (Japanese Patent Application Laid-Open No. 9-118784), etc. Method (JP-A-6-248116)
And so on. However, in these techniques, the problem of scorch due to the use of the adjuvant,
There is a problem in performance such as insufficient improvement in strength, and there is a problem in that the solution is not sufficiently solved for practical use.

Accordingly, for example, Japanese Patent No. 2635882, Japanese Patent Application Laid-Open No. 8-259735, and Japanese Patent Application Laid-Open No. 8-259
No. 736 and JP-A-8-259739 disclose methods of performing kneading in two stages. However, according to these methods, mixing and reaction are performed simultaneously, so that it is difficult to achieve the above-mentioned performance at the same time. There is a problem that compatibility between workability and silica performance (rolling resistance, wet performance) is insufficient.

[0005]

In view of the above facts, it is an object of the present invention to provide a rubber composition having a good balance between rolling performance, wet performance and abrasion resistance in which a silane coupling agent and silica react efficiently. To provide things.

[0006]

The present invention relates to (a) a vulcanizable polymer, silica and a compound of the formula (1): Z—R—S _n —R—Z;
H, Formula (3) Z-R-NH ₂ , Formula (4) Z-CH = CH
₂ and the formula (5) ZR-Cl (in the formulas (1) to (5),
R is a divalent hydrocarbon group having 1 to 18 carbon atoms, n represents 2-8 integer, Z is ^{_{-Si (R 1) 2 R 2}} , -SiR 1 (R 2)
₂ or -Si (R ² ) ₃ (where R ¹ has 1 to ¹ carbon atoms)
4 alkyl groups, cyclohexyl groups or phenyl groups, and R ² is an alkoxy group having 1 to 8 carbon atoms or a cycloalkoxy group having 5 to 8 carbon atoms). After mixing at a temperature lower than 130 ° C. for 30 seconds to 30 minutes, (b) 130
At 180 ° C. for 1 to 20 minutes, and then (c) adding a vulcanizing agent and a vulcanization accelerator, and
It relates to a rubber composition obtained by mixing for 20 minutes.

In this case, it is preferable that after the mixing in the step (a), the temperature of the rubber mixture is cooled to 100 ° C. or less, and then the mixing in the step (b) is performed.

The rubber composition preferably has a ratio of tensile strength M300 after vulcanization to M100 of 4 or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present invention comprises three stages of mixing steps (a) to (c). First, as step (a), a vulcanizable polymer, silica and a compound of the formula (1) _{: Z-R-S n -R} -Z, wherein (2) Z-R-S
H, Formula (3) Z-R-NH ₂ , Formula (4) Z-CH = CH
₂ and the formula (5) ZR-Cl (in the formulas (1) to (5),
R is a divalent hydrocarbon group having 1 to 18 carbon atoms, n represents 2-8 integer, Z is ^{_{-Si (R 1) 2 R 2}} , -SiR 1 (R 2)
₂ or -Si (R ² ) ₃ (where R ¹ has 1 to ¹ carbon atoms)
4 alkyl groups, cyclohexyl groups or phenyl groups, and R ² is an alkoxy group having 1 to 8 carbon atoms or a cycloalkoxy group having 5 to 8 carbon atoms). Mix for 30 seconds to 30 minutes at a temperature less than 130C. This mixing step (a) is mainly performed to sufficiently mix the polymer, silica, and the silane coupling agent.

The vulcanizable polymer is not particularly limited as long as it is conventionally used in rubber compositions and can be vulcanized. For example, styrene butadiene rubber (SBR), natural rubber (NR) , Isoprene rubber (I
R), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), bromide of p-methylstyrene / isobutylene copolymer, and the like. These can be used alone or in any combination.

The silica used in the present invention is not particularly limited as long as it has been conventionally used in the field of rubber compositions. However, it imparts a reinforcing effect, does not deteriorate dispersibility, and generates heat. From the viewpoint of suppressing the nitrogen content, the nitrogen adsorption specific surface area is preferably from 100 to 300 m ² / g.
Particularly preferred is 50 m ² / g.

The amount of the silica in the present invention may be 10 to 150 parts by weight based on 100 parts by weight of the polymer.

[0013] As the silane coupling agent used in the present invention is then in terms of reinforcing property and workability, the formula (1): Z-R- S n -R-Z, wherein (2) Z-R-S
H, Formula (3) Z-R-NH ₂ , Formula (4) Z-CH = CH
₂ and formula (5) ZR-Cl (formulas (1) to (5)
Wherein R is a divalent hydrocarbon group having 1 to 18 carbon atoms, and n is 2 to 2
8, 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, cyclohexyl group or phenyl group, and R ² is an alkoxy group having 1 to 8 carbon atoms or 5 to 8 carbon atoms) Or a silane coupling agent represented by formula (1), which is a cycloalkoxy group).

Examples of the silane coupling agent represented by the formula (1) include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (2-triethoxysilylpropyl). ) Tetrasulfide and the like.

Examples of the silane coupling agent represented by the formula (2) include 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane. Is raised.

Examples of the silane coupling agent represented by the formula (3) include N-β (aminoethyl) -γ-aminopropyltrimethoxysilane and N-β (aminoethyl)
-Γ-aminopropylmethyldimethoxysilane and the like.

Examples of the silane coupling agent represented by the formula (4) include vinyl tris (β-methoxyethoxy silane), vinyl triethoxy silane, and vinyl trimethoxy silane.

The silane coupling agent represented by the formula (5) includes, for example, vinylitrichlorosilane.

Of these, bis (3-triethoxysilylpropyl) tetrasulfide is preferably used from the viewpoints of reinforcement and processability.

The compounding amount of the silane coupling agent may be 2 to 20% by weight of the silica.

In the present invention, the above components are first mixed in step (a). As the mixing means at this time, a conventional mechanical mixing means such as a Banbury mixer or a kneader can be used.

The mixing temperature in the step (a) is preferably lower than 130 ° C. so that the viscosity of the rubber composition during mixing is not lowered and sufficient dispersion of the filler is not hindered. From the viewpoint of not increasing the viscosity, the temperature is particularly preferably from 80 to 120 ° C.

The mixing time in the step (a) may be from 30 seconds to 30 minutes from the viewpoint of dispersibility, and further from 30 seconds to 20 minutes from the viewpoint of dispersibility and cost (step). It is preferred that

Next, in the present invention, the rubber mixture obtained in the step (a) is further mixed in the step (b). This mixing step (b) is performed for chemically bonding the silica and the silane coupling agent.

Here, the rubber mixture obtained in the step (a) is obtained from the viewpoint of processability (does not increase the viscosity).
It is preferable that the mixture is cooled to 100 ° C. or lower, preferably about room temperature, by leaving it to cool or water, and then subjected to the mixing in the step (b).

The mixing temperature in the step (b) is set at 13 in view of the reaction between silica and the silane coupling agent.
It is sufficient that the temperature is 0 to 180 ° C., but the property of silica is sufficiently exhibited to prevent gelation caused by promotion of a crosslinking reaction by sulfur atoms that can be contained in a silane coupling agent, and to prevent deterioration of rubber skin accompanying the gelation. From the point, 145-1
Particularly preferred is 65 ° C.

The mixing time is preferably from 1 to 20 minutes from the viewpoint that the reaction is sufficiently performed, and from 1 to 1 from the viewpoint that the viscosity is not increased.
It is particularly preferred that the time is 0 minutes.

The mixing means in the step (b) may be the same as that used in the step (a).

Finally, in the present invention, in step (c), a vulcanizing agent and a vulcanization accelerator (vulcanizing system) are added to the rubber mixture obtained in step (b) and mixed. This mixing step (c) is mainly performed to uniformly disperse the vulcanizing agent and the vulcanization accelerator in the rubber composition so that the obtained rubber composition is cured uniformly when vulcanized. The vulcanizing agent is added to the polymer in an amount of 100 parts by weight.
5 to 3 parts by weight and the vulcanization accelerator may be 0.5 to 5 parts by weight.

The mixing means at this time may be any as long as it can disperse the vulcanizing agent, and examples thereof include an open roll, a Banbury mixer, and a kneader.

The mixing temperature in the mixing step (c) may be a temperature equal to or lower than the vulcanization temperature in view of the dispersibility of the vulcanizing agent and the prevention of rubber burning. The temperature below the vulcanization temperature varies depending on the type and size of the product, but usually may be 80 to 120 ° C.

The mixing time is preferably from 1 to 20 minutes from the viewpoint of dispersibility, and more preferably from 1 to 10 minutes from the viewpoint of preventing burning of the rubber.

In the rubber composition of the present invention, in addition to the above-mentioned components, for example, a white filler such as talc and clay, a filler such as carbon black, a paraffin-based filler,
Softeners such as aroma and naphthenic process oils,
Coumarone indene resin, rosin-based resin, tackifier such as cyclopentadiene-based resin, vulcanization aid such as stearic acid, zinc oxide, antioxidant, etc., as long as the effects of the present invention are not impaired, Can be appropriately blended. For example, when a softener is used, the amount may be 0 to 250 parts by weight based on 100 parts by weight of the polymer.
However, when these components are blended, step (a)
Any of the steps (a) to (c) may be used, but it is preferable to mix them in the step (b) from the viewpoint of the dispersibility of the silica and the silane coupling agent.

As described above, the rubber composition of the present invention is obtained through steps (a) to (c). Among the obtained rubber compositions, from the point that the reaction between silica and the silane coupling agent proceeds efficiently, the tensile strength M30 after vulcanization is obtained.
It is preferred that the ratio of 0 to M100 (M300 / M100) is 4 or more. That is, the more efficiently the reaction between the silica and the silane coupling agent proceeds, the more M300
/ M100 increases. Although there is no particular upper limit, it is usually about 6. In addition, the tensile strength referred to in the present invention means a value measured in accordance with JIS K6301.

The rubber composition of the present invention can be applied to, for example, a tread or a shoe bottom of a tire from the viewpoint of improving rolling resistance, wet performance and abrasion resistance.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0037]

EXAMPLES First, Table 1 shows the components used in the examples and the amounts thereof.

Examples 1 to 4 Each step (a) of the present invention was carried out according to the mixing ratio shown in Table 1.
The rubber compositions 1 to 4 were obtained by the method of the present invention under the conditions shown in Table 2 with the conditions (c) to (c). In steps (a) and (b), a BR type Banbury mixer was used, and in step (c), an open roll was used. Step (a)
The resulting rubber mixture was allowed to cool to room temperature and then subjected to step (b).

Then, the obtained rubber compositions 1 to 4 were mixed with 17
Vulcanized products 1 to 4 were obtained by press vulcanization at 0 ° C for 20 minutes, and evaluated by the following test methods. Table 2 shows the results.

[Test Method] Mooney test, tensile test and hardness test: JIS
According to K6301, Mooney viscosity, M100, M3
00, T _B, was measured E _B and hardness. If the Mooney viscosity is 100 or less, the processability is not inferior. Also, M30
The larger the value of 0 / M100, the more the reaction between the silica and the silane coupling agent proceeds, which is preferable.

Viscoelasticity test: E ^* and tan δ using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho under the conditions of a temperature of 70 ° C., a dynamic strain of 2% and an initial strain of 10%.
Was measured, and the rolling resistance characteristics were evaluated. The lower the tan δ, the better.

Toluene swelling degree: The vulcanized product was immersed in toluene at 20 ° C. for 48 hours, and the volume change before and after immersion was examined.
The degree of toluene swelling was determined according to the formula: toluene swelling degree (%) = (volume after swelling / volume before swelling) × 100.

Abrasion test: Using a Lambourn abrasion tester, temperature 23 ° C., slip rate 20%, test time 5 minutes,
Load weight 2kg. The amount of loss was calculated by volume under the condition of the amount of falling sand of 20 g / min.
Abrasion index = (Loss of Comparative Example 1 / Loss of each Example) ×
The wear index was determined according to 100.

Wet skid test: Using a portable skid tester manufactured by Stanley, ASTM E-
The wet skid index was determined by the formula: wet skid index = (index of each example / index of comparative example 1) × 100 according to the method of 303-83. The higher the wet skid index, the better the wet performance.

Workability: After the step (a), the workability was evaluated as ○, Δ and × from the united rubber mixture a when the rubber mixture a was discharged from the banbury. If the unity of the rubber is good and there is no difficulty in the subsequent roll work, ○, if the unity of the rubber is slightly inferior and there is some difficulty in the subsequent roll work, △, the rubber will be discharged in a rough state. When the roll work was extremely difficult, it was marked as x.

Comparative Examples 1 and 2 Comparative rubber compositions 1 and 2 were prepared in the same manner as in Example 1 except that step (b) was not performed and the conditions shown in Table 2 were used.
Was manufactured and the same test as in the example was performed. Table 2 shows the results
Shown in

Comparative Examples 3 to 9 Comparative rubber compositions 3 to 9 were produced in the same manner as in Example 1 except that the conditions shown in Table 2 were used, and the same tests as those in Examples were performed. Table 2 shows the results.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

According to the present invention, a silane coupling agent and silica react efficiently, and a rubber composition having excellent rolling resistance, wet performance and abrasion resistance can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/54 C08K 5/54 (72) Inventor Ikuyo Tamura 3-22-13-205 (72) Inventor Noriko Yagi 5-11-16 Owada, Nishiyodogawa-ku, Osaka-shi

Claims (3)

[Claims] (A) vulcanizable polymer, silica and formula (1): Z—R—S _n —R—Z, formula (2) Z—R—S
H, Formula (3) Z-R-NH ₂ , Formula (4) Z-CH = CH
₂ and the formula (5) ZR-Cl (in the formulas (1) to (5),
R is a divalent hydrocarbon group having 1 to 18 carbon atoms, n represents 2-8 integer, Z is ^{_{-Si (R 1) 2 R 2}} , -SiR 1 (R 2)
₂ or -Si (R ² ) ₃ (where R ¹ has 1 to ¹ carbon atoms)
4 alkyl group, cyclohexyl group or phenyl group, and R ² is an alkoxy group having 1 to 8 carbon atoms or a cycloalkoxy group having 5 to 8 carbon atoms). After mixing at a temperature lower than 130 ° C. for 30 seconds to 30 minutes, (b) 130
At 180 ° C. for 1 to 20 minutes, and then (c) adding a vulcanizing agent and a vulcanization accelerator, and
A rubber composition obtained by mixing for 20 minutes. 2. The rubber composition according to claim 1, wherein after the mixing in the step (a), the temperature of the rubber mixture is cooled to 100 ° C. or less, and then the mixing in the step (b) is performed. 3. The rubber composition according to claim 1, wherein the ratio of the tensile strength M300 after vulcanization to M100 is 4 or more.