JP2002121327A - Tread rubber composition and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silica-containing rubber composition having at a once excellent wetting ability and rolling resistance, and having improved kneading processability. SOLUTION: This rubber composition for use in treads comprises 100 pts.wt. of a diene rubber, 30-90 pts.wt. of silica as a filler, a silane coupling agent, 2-20 pts.wt. of a polyethylene glycol, sulfur and a vulcanization accelerator. The manufacturing method comprises step 1: kneading the diene rubber, the silica and the silane coupling agent at 130-140 deg.C, step 2: adding the polyethylene glycol at 150-170 deg.C for further kneading, and step 3: adding the sulfur and vulcanization accelerator for further kneading.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition for a tread and a method for producing the same, and more particularly to a rubber composition for a tread excellent in processability, wet performance and rolling resistance, and a method for producing the same.

[0002]

2. Description of the Related Art To improve the wet performance (grip and braking distance in steering stability) of a tire, generally,
A method of using silica as a filler in a tread rubber composition and a method of increasing hysteresis at a low temperature are known.

[0003] One effective technique for increasing hysteresis at low temperatures is to use a rubber composition having a high glass transition temperature. However, a rubber composition having a high glass transition temperature can improve the wet performance, but at the same time, has a problem that the hysteresis at a high temperature increases to increase the rolling resistance, and the abrasion resistance tends to decrease. To solve this problem, Japanese Patent Laid-Open No.
No. 79667 describes a method of using styrene / isoprene / butadiene rubber (SIBR) in a rubber composition. According to this method, rolling resistance, wet traction and abrasion resistance can be slightly improved, but it is difficult to achieve both wet performance and rolling resistance in a high dimension, and there is no mention of workability. .

[0004] When silica is used, if the temperature becomes high during kneading, the silica will agglomerate and the viscosity will increase, and the kneaded dough will suffer from poor workability. In the rubber composition filled with silica as described above, it is a trade-off between high-dimensional compatibility between wet performance and rolling resistance including processability, but from the viewpoint of ensuring safety and improving the environment during automobile driving in rainy weather. Therefore, a quick improvement method is required.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a silica-containing rubber composition that achieves both high wet performance and high rolling resistance while improving the processability during kneading.

[0006]

According to the present invention, silica is used as a filler in an amount of 30 to 90 parts by weight based on 100 parts by weight of a diene rubber.
1 part by weight, a silane coupling agent, 2 to 20 parts by weight of polyethylene glycol, a method for producing a rubber composition for a tread containing sulfur and a vulcanization accelerator, wherein a diene rubber, silica and a silane coupling agent are added in an amount of 130 to 14
Step 1: kneading at 0 ° C.
The present invention relates to a production method comprising a step 2 of kneading at 0 to 170 ° C. and a step 3 of kneading sulfur and a vulcanization accelerator.

The number average molecular weight of the polyethylene glycol is preferably from 200 to 6000.

Further, the present invention relates to a rubber composition for a tread obtained by the above-mentioned production method.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber composition of the present invention contains a diene rubber as a rubber component.

As the diene rubber, for example, styrene / isoprene / butadiene rubber (SIBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), 1,4-added isoprene rubber (IR), ethylene-propylene- Examples include diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and natural rubber (NR).

In the rubber composition of the present invention, the diene rubber 1
30 to 90 parts by weight, preferably 40 to 80 parts by weight, of silica is blended as a filler with respect to 00 parts by weight. If the amount of silica is less than 30 parts by weight, the effect of adding silica, that is, the effect in terms of wet performance and rolling resistance is not seen, and if it exceeds 90 parts by weight, the dispersion of silica itself becomes poor, resulting in wear and the like. The performance of is reduced.

The nitrogen adsorption specific surface area (N ₂ S) of the silica
A) is preferably from 50 to 300 m ² / g. N ₂ SA is 50
When the silica is less than m ² / g, the dispersibility improving effect and the reinforcing effect tend to be small, and when the silica exceeds 300 m ² / g, the dispersibility is poor and the heat generation of the tire tends to increase.

The silica is not particularly limited, but dry silica (anhydrous silicic acid), wet silica (hydrous silicic acid) and the like can be used, and the wet silica is preferably used. Particularly suitable wet-process silicas include, for example, Ultrasil VN manufactured by Degussa.
3 (trade name) and Nip Seal VN3 AQ (trade name) manufactured by Nippon Silica Industry Co., Ltd.

The rubber composition of the present invention further contains a silane coupling agent. As a silane coupling agent,
There is no particular limitation as long as it is conventionally used in the field of tires. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-
Trimethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylpropyl) tetrasulfide, 3-mercaptopropyltriethoxysilane, 2-
Mercaptoethyltrimethoxysilane and the like,
These can be used alone or in any combination. Among them, bis (3-triethoxysilylpropyl) tetrasulfide and 3-mercaptopropyltriethoxysilane are preferably used from the viewpoint of the reinforcing effect of the silane coupling agent and processability, and further from the viewpoint of processability. It is particularly preferable to use bis (3-triethoxysilylpropyl) tetrasulfide.

[0015] The amount of the silane coupling agent is from 2 to 2 of silica in order to sufficiently perform the coupling.
The content is preferably 20% by weight, and more preferably 4 to 15% by weight from the viewpoint of preventing a reduction in workability.

The rubber composition of the present invention comprises a diene rubber 10
0 parts by weight of polyethylene glycol (PEG) 2
-30 parts by weight, preferably 3-10 parts by weight.
If the amount of PEG is less than 2 parts by weight, a decrease in viscosity cannot be expected, and if it exceeds 30 parts by weight, the scorch time becomes short.

The number average molecular weight of the PEG is 200 to 6
000 is preferred. If the number average molecular weight of PEG is less than 200, the abrasion resistance tends to decrease,
If it exceeds 00, a reduction in the rolling resistance tends to be unable to be expected.

The rubber composition of the present invention comprises a diene rubber 10
Sulfur is preferably used as a vulcanizing agent in an amount of 0.5 part by weight.
To 3.0 parts by weight, more preferably 1.0 to 2.0 parts by weight. If the amount of sulfur is less than 0.5 parts by weight, the vulcanization rate tends to be low and the vulcanization tends to be insufficient. If the amount exceeds 3.0 parts by weight, the vulcanization rate tends to be high and the tendency to scorch. is there.

In the rubber composition of the present invention, a guanidine-based rubber composition
A vulcanization accelerator such as an aldehyde-amine type, aldehyde-ammonia type, thiazole type, sulfenamide type, thiourea type, thiuram type, dithiocarbamate type or xandate type compound is blended. These can be used alone or 2
More than one species can be used in combination. The compounding amount of the vulcanization accelerator is preferably 1.0 to 4.0 parts by weight, more preferably 1.5 to 3.0 parts by weight. If the compounding amount of the vulcanization accelerator is less than 1.0 part by weight, the vulcanization rate tends to be low, and vulcanization tends to be insufficient. There is.

The rubber composition of the present invention may further comprise, as other compounding agents, a softening agent such as a paraffinic, aroma-based, or naphthenic-based process oil; An agent; a vulcanization aid such as stearic acid and zinc oxide; an antioxidant, and the like can be appropriately compounded as needed within a range not to impair the effects of the present invention.

The rubber composition of the present invention is kneaded through three steps.

In step 1, the diene rubber, silica and silane coupling agent are kneaded. The kneading temperature in step 1 is a usual kneading temperature of 130 to 140 ° C.
It can be.

In step 2, the above-mentioned PEG and a compounding agent appropriately compounded as necessary are kneaded. Step 2
The kneading temperature is preferably 150 to 170 ° C. If it is lower than 150 ° C., there is no difference from the conventional results, and there is no effect of reducing the viscosity. If it is higher than 170 ° C., the viscosity increases, and the kneaded dough becomes bad.

In step 3, the sulfur and the vulcanization accelerator are further kneaded. The kneading temperature in step 3 is 80 to 1
Preferably it is 10 ° C. If the kneading temperature in step 3 is lower than 80 ° C, the chemicals tend to be poorly dispersed and vulcanization tends to be insufficient. If the kneading temperature exceeds 110 ° C, vulcanization starts and scorching tends to occur.

The unvulcanized rubber thus obtained is preferably at 150 to 190 ° C., more preferably at 160 to 190 ° C.
It can be vulcanized at 180 ° C. to obtain a vulcanized rubber.

The rubber composition of the present invention can be used as a tire tread. The tire is manufactured by a usual method. That is, the unvulcanized tire is formed by extruding a tread member in an unvulcanized stage, and pasting and molding the same on a tire molding machine by an ordinary method. The unvulcanized tire is heated and pressed in a vulcanizer to obtain a tire. The tire thus obtained is excellent in wet performance, rolling resistance, and the like.

[0027]

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

Examples 1 to 3 and Comparative Examples 1 to 7 (Reagent) E-SBR: Nippol 9520 manufactured by Zeon Corporation
(Oil extension: 37.5 parts by weight with respect to 100 parts by weight of a rubber component having a styrene unit amount of 35% by weight) BR: BR150B (Hicis B) manufactured by Ube Industries, Ltd.
R: cis 1,4-butadiene unit amount 98% by weight) Silica: Ultrasil VN3 manufactured by Degussa (BET specific surface area: 175 m ² / g, DBP oil absorption: 210 ml / 1)
00g) PEG 600: Polyethylene glycol manufactured by NOF Corporation (number average molecular weight: 600) Sulfur: powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator: TBBS (compound name N) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. -Tert-butyl-2-benzothiazolyl-
Sulfenamide)

(Preparation of Test Sample) According to the composition shown in Table 1, kneading was performed in three steps. That is, in step 1, E-SBR, BR and silica
And kneaded. In step 2, PEG was further added to Examples 1 to 3 and Comparative Examples 4 to 7 and kneaded at the temperatures shown in Table 1. In step 3, sulfur and a vulcanization accelerator were further blended and kneaded at 100 ° C.

(Test method) (Mooney viscosity and scorch time) JIS K63
According to No. 01, Mooney viscosity and scorch time were measured at 130 ° C. using MV202 manufactured by Shimadzu Corporation. The lower the value of the Mooney viscosity, the better the workability. If the scorch time is less than 10 minutes, rubber scorch will occur, which is not preferable.

(Measurement of Viscoelasticity) Using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., at a temperature of 70 ° C. and an initial strain of 10
%, Dynamic strain ± 1%, and frequency 10 Hz, the loss tangent (tan δ) was measured. The smaller the tan δ, the more advantageous the rolling resistance.

(Abrasion Resistance) The measurement was performed using a Lambourn abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd. under the conditions of a load of 2.0 kg, a slip ratio of 60%, and a measurement time of 2 minutes.

The volume loss was calculated from the change in weight, and an index (Lambourn abrasion index) was indicated with the case of Comparative Example 4 taken as 100. The larger the index, the better the wear resistance performance.

(Wet performance) Size 205 / 65R5
Tires are manufactured in a conventional manner, and the maximum friction coefficient (μ _MAX ) when a brake is applied at a speed of 64 km / h on a test course on an asphalt road surface where water is sprayed is measured using a traction test vehicle equipped with the tires. Then, an index (wet performance index) is indicated by setting the case of Comparative Example 4 to 100. The higher the index, the better the wet performance.

The results are shown in Table 1.

[0036]

[Table 1]

[0037]

According to the present invention, by blending PEG and kneading at a high temperature, a silica blend which can achieve both wet performance and rolling resistance, which are characteristics of silica, at a high level without impairing processability. A tread rubber composition can be obtained.

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Claims (3)

[Claims] 1. A rubber for a tread in which 30 to 90 parts by weight of silica, a silane coupling agent, 2 to 20 parts by weight of polyethylene glycol, sulfur and a vulcanization accelerator are blended with respect to 100 parts by weight of a diene rubber. A method for producing a composition, comprising: a step 1 of kneading a diene rubber, silica and a silane coupling agent at 130 to 140 ° C, a step 2 of kneading polyethylene glycol at 150 to 170 ° C, and sulfur and a vulcanization accelerator. A kneading process. 2. The method for producing a rubber composition for a tread according to claim 1, wherein the number average molecular weight of the polyethylene glycol is from 200 to 6000. 3. A rubber composition for a tread obtained by the production method according to claim 1.