JP2001011245A - Rubber composition for tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition which can give a vulcanizate almost free from voids and pores by compounding a rubber component comprising a specified amount of a halogenated butyl rubber and a diene rubber with a specified amount of silica treated with a silane coupling agent. SOLUTION: This composition is prepared by compounding 100 pts.wt. rubber component comprising 5-75 pts.wt. at least one member selected from a halogenated butyl rubber and a halogenated isobutylene/p-methylstyrene copolymer and 25-95 pts.wt. diene rubber with 40-150 pts.wt. silica treated with a silane coupling agent. That is to say, when silica pretreated with a silane coupling by mixing is used, the alcohol formed when the coupling agent is reacted with the silica is evaporated and does not remain in the rubber composition. It is desirable that the silica treated with the silane coupling agent is a product obtained by heat-treating silica and an S-containing silica coupling agent (e.g. a compound of the formula).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rubber composition for a tread. More specifically, a rubber composition for a tread using a halogenated butyl rubber and a rubber containing one or more halides of an isobutylene / p-methylstyrene copolymer, silica as a filler, and a silane coupling agent is used. The present invention relates to a rubber composition which is hardly porous even when cured, and hardly generates voids and pores.

[0002]

2. Description of the Related Art It is known that wet performance is improved by using high styrene SBR, solution SBR, or the like as a rubber. However, this method is used because it becomes hard at low temperatures. Temperature range is limited.

As a method for remedying this drawback, there is known a method in which a halogenated butyl rubber or a halide of isobutylene / p-methylstyrene copolymer is used to increase the coefficient of friction when wet without becoming hard at low temperatures. I have.

[0004] For example, Japanese Patent Application Laid-Open No. 9-241426 discloses that a rubber component containing a halide of a copolymer of isomonoolefin and p-alkylstyrene contains carbon having a specific dibutyl phthalate oil absorption (DBP). It is described that a pneumatic tire using a rubber composition for a tire tread containing black can achieve both improvement in wet skid resistance and reduction in rolling resistance without lowering fracture resistance and wear resistance. Have been. JP-A-8-225683 discloses that a diene rubber and a halide of isobutylene / p-methylstyrene copolymer are used as a rubber component, carbon black is contained, and a peak temperature of a loss coefficient of a vulcanized product is-. It is described that the rolling resistance of a tire having a tread manufactured from a rubber composition of 15 ° C. or lower is low and the wet grip property is improved.

[0005] Further, a pneumatic tire having a tread formed by using a composition obtained by adding a heat-treated precipitated silica to a diene rubber may have good rolling resistance, wet skid characteristics and abrasion resistance. It is known that the compounding of silica is effective for the purpose of enhancing the wet performance (for example, Japanese Patent Application Laid-Open No.
157441, JP-A-9-156307).

Further, by using a halogenated butyl rubber or a halide of isobutylene / p-methylstyrene copolymer as a rubber and using silica as a filler, the wet performance can be dramatically improved without impairing the low-temperature characteristics. It is stated that it can be improved.

[0007] For example, Japanese Patent Application Laid-Open No. 9-324069 discloses that a rubber component containing a modified copolymer obtained by halogenating a copolymer comprising isomonoolefin and p-alkylstyrene is mixed with carbon as a reinforcing filler. It is described that a pneumatic tire using a rubber composition for a tire tread blended with black and / or silica can be manufactured and drastically improved wet performance without impairing low-temperature performance.

Japanese Patent Application Laid-Open No. Hei 7-304903 does not disclose the wet performance.
Butadiene copolymer rubber, cis 1,4-polyisoprene natural rubber and halogenated / isobutylene / p-methylstyrene copolymer are used as a skeletal rubber component, and in some cases, cis 1,4-polybutadiene rubber and styrene / butadiene copolymer A pneumatic rubber tire with a tread made from a rubber composition reinforced with silica, compounded with other additional rubber components such as coalesced rubber, has excellent static friction characteristics, and has a well-balanced rolling resistance and abrasion resistance. Has been described.

However, the prior art has a problem in that the alcohol produced, for example, ethanol when the silane coupling agent used with silica reacts with the silica, makes the produced tire porous. Particularly, halogenated butyl rubber or a halide of isobutylene / p-methylstyrene copolymer is excellent in air permeability resistance (impervious to air), so that the generated alcohol tends to remain in the rubber composition, and is used for a porous rubber. Prone.

[0010]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, mixing of silica and a silane coupling agent is generally performed in a rubber kneading step. In the case where both are mixed and reacted, the generated alcohol tends to remain in the rubber and easily become a porous rubber, but if silica and a silane coupling agent are mixed and pre-treated,
The generated alcohol evaporates, reaching the idea that the above problem can be solved, and completed the present invention.

That is, the present invention relates to a method for producing a mixture of at least one of halogenated butyl rubber and a halide of isobutylene / p-methylstyrene copolymer in an amount of 5 to 75 parts by weight (hereinafter referred to as "parts") with 25 to 95 parts of a diene rubber. Silica 40-15 treated with a silane coupling agent, based on 100 parts in total
2. The rubber composition according to claim 1, wherein the rubber composition for a tread containing 0 parts (claim 1) and the silica treated with a silane coupling agent have been previously heat-treated with silica and a silane coupling agent containing sulfur. (Claim 2).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber used in the rubber composition for a tread of the present invention comprises 5-75 parts of at least one halogenated butyl rubber and a halide of an isobutylene / p-methylstyrene copolymer, and a diene-based rubber. A total amount of rubber of 95 to 25 parts is 100 parts of rubber.

The halogenated butyl rubber and the halide of isobutylene / p-methylstyrene copolymer
The above species are used for imparting good air permeation resistance and low temperature properties and good wet performance.

The halogenated butyl rubber is not particularly limited as long as it is generally used for the production of a rubber composition for a tread, but usually has a halogen content of 1.1 to 1.3 wt. % (Hereinafter referred to as%), and brominated butyl rubber of 1.8 to 2.4%
It is preferably used in terms of high vulcanization rate. The Mooney viscosity (ML) of the halogenated butyl rubber
( _{1 + 8} (125 ° C.)) is preferably from 20 to 60 from the viewpoint of workability. Specific examples of preferable halogenated butyl rubber include, for example, JS manufactured by JSR Corporation.
R BROBOBUTYL2244 (trade name), Chlorobutyl 1066 (trade name) manufactured by Exxon Chemical Co., Ltd., Chlorobutyl 1068 (trade name) manufactured by Exxon Chemical Co., Ltd.
And so on.

The halide of the isobutylene / p-methylstyrene copolymer is not particularly limited as long as it is generally used in the production of a rubber composition for a tread, but a bromide is generally used and isobutylene units /
The p-methylstyrene unit is 90/10 to 98 by weight ratio.
/ 2, those having a bromine content of 0.5 to 5% are preferably used from the viewpoint of co-crosslinkability. Preferred isobutylene / p
Specific examples of the halide of a methylstyrene copolymer include, for example, EXXPRO manufactured by Exxon Chemical Co., Ltd.
90-10 (trade name) Mooney viscosity (ML _{1 + 8} 125
C is 45 ± 5), and EXXPRO 93-5.

The diene rubber used in the present invention can be used as long as it is used as a so-called diene rubber in a rubber composition for a tread, and is not particularly limited. Thousands to five millions are used. Specific examples of the diene rubber include, for example, natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NB)
R), chloroprene rubber (CR) and the like. These may be used alone or in combination of two or more. Among them, natural rubber and styrene-butadiene rubber are preferred from the viewpoint of mechanical strength, fatigue resistance and heat resistance.

At least one of the halogenated butyl rubber and the isobutylene / p-methylstyrene copolymer
The proportions of the halogenated butyl rubber and the diene rubber are 5 to 75 parts, more preferably 25 to 60 parts, and the diene rubber 25 to 95 parts so that the total amount is 100 parts. Parts, or even 40 to 75 parts.
If the proportion of the halogenated butyl rubber is too small, sufficient wet performance cannot be obtained, and if it is too large, the abrasion resistance is poor.

The silica treated with the silane coupling agent used in the present invention is used to improve the low rolling friction resistance, wet and dry grip properties, abrasion resistance and workability of the manufactured tire. Component.

The silica treated with the silane coupling agent means that the silica and the silane coupling agent are separately added to the halogenated butyl rubber and the diene rubber, and the silica is treated with the silane coupling agent during kneading. Means that silica previously treated with a silane coupling agent is used.

When treating silica with a silane coupling agent, the silane coupling agent is usually used in an amount of 1 to 10%, more preferably 1 to 8%, based on silica. When the use ratio of the silane coupling agent to the silica is too small, sufficient rubber reinforcing properties cannot be obtained, and when it is too large, the silane coupling agent is excessively used, which is uneconomical. It is.

After attaching the silane coupling agent to the silica, the silica and the silane coupling agent may be allowed to react with each other by allowing the silica to react with the silica. Is preferable from the viewpoint of processability.

Examples of the silica include dry silica (silicic anhydride) and wet silica (hydrous silicic acid). Among them, wet-process silica is preferred from the viewpoint of rubber reinforcement. Specific examples of the wet-process silica include Ultrasil VN3 (trade name) manufactured by Degussa, and Nip Seal VN3 AQ (trade name) manufactured by Nippon Silica Co., Ltd.

The silane coupling agent has a function of preferably chemically bonding to both silica and rubber, and preferably chemically bonding silica and rubber via itself.

As the silane coupling agent, conventional
Any silane used in combination with silica as filler
Coupling agents can be used. The silanka
Specific examples of the pulling agent include, for example, general formula (1): ZRS_n-RZ (1), General formula (2): ZR-SH (2), General formula (3): ZR-NH_Two (3), General formula (4): Z-CH = CH_Two (4) or general formula (5): ZR-Cl (5) (wherein, R is a hydrocarbon group having 1 to 18 carbon atoms, and n is 2 to 8)
Z is -Si (R¹)_Two(OR^Two), -SiR
¹(OR^Two)_Two, Or -Si (OR^Two)_Three(However, R ¹Is
An alkyl group having 1 to 4 carbon atoms, a cyclohexyl group or
Phenyl group, OR^TwoIs an alkoxy group having 1 to 8 carbon atoms or
A cycloalkoxy group having 5 to 8 carbon atoms).
Silane coupling agents.

In the above formula, Z is -Si (R
¹ ) ₂ (OR ² ), -SiR ¹ (OR ² ) ₂ or -Si (R
Are shown in ²⁾ _3, R ¹ is a methyl group, an ethyl group, a propyl group, an alkyl group having 1 to 4 carbon atoms such as butyl group, cyclohexyl group or a phenyl group, OR ² is a methoxy group, an ethoxy group, a butoxy And an aryloxy group or an aralkyloxy group having an aromatic ring having 5 to 8 carbon atoms, such as an alkoxy group having 1 to 8 carbon atoms or a phenoxy group, a benzyloxy group, or the like. R is a divalent hydrocarbon group having 1 to 18 carbon atoms such as an ethylene group and a propylene group.

Specific examples of the silane coupling agent represented by the general formula (1) include, for example,

[0027]

Embedded image

And the like. As a commercially available product,
An example is Si69 (3,3'-bis (triethoxysilylpropyl) tetrasulfide) manufactured by Degussa.

Specific examples of the silane coupling agent represented by the general formula (2) include, for example,

[0030]

Embedded image

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

Specific examples of the silane coupling agent represented by the general formula (3) include, for example,

[0033]

Embedded image

And the like. As a commercially available product,
An example is KBM903 (γ-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

Specific examples of the silane coupling agent represented by the general formula (4) include, for example,

[0036]

Embedded image

And the like. As a commercially available product,
An example is KBM1003 (vinyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

Specific examples of the silane coupling agent represented by the general formula (5) include, for example,

[0039]

Embedded image

And the like. Examples of commercially available products include KBM703 (γ-chloropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

Among the silane coupling agents, 3,3'-bis (triethoxysilylpropyl) tetrasulfide is preferable from the viewpoint of achieving both the effect of adding the silane coupling agent (scorch) and the cost.

In the rubber composition of the present invention, in addition to the above-mentioned components, for example, white fillers such as talc and clay other than the above-mentioned silica, fillers such as carbon black, paraffin-based, aroma-based and naphthene-based process oils Softeners, tackifiers such as coumarone indene resin, rosin resin, cyclopentadiene resin, vulcanizing agents such as sulfur and peroxide, vulcanization accelerators, vulcanization aids such as stearic acid and zinc oxide Components generally used in the manufacture of tires, such as an agent and an antioxidant, may be appropriately compounded as long as the effects of the present invention are not impaired. When these components are used, rubber component 1
For example, 20 to 200 parts for a filler excluding silica treated with the silane coupling agent, 10 to 200 parts for a softener, and 5 to 50 parts for a tackifier, based on 00 parts. Is preferred.

In the case of a vulcanizing agent, a vulcanization accelerator and a vulcanization aid, the total amount is preferably 4 to 15 parts with respect to 100 parts of the rubber component. Part is preferred.

The rubber composition of the present invention can be produced by a conventional method using a Banbury mixer, an open roll or the like. At this time, since a silane coupling agent and silica that have been pre-treated are used, no reaction occurs between the silane coupling agent and silica in the kneading step, and no alcohol is generated at this time.
Also in the case of a rubber composition using a halogenated butyl rubber, the amount of alcohol remaining in the composition is reduced. As a result, even when rubber is used, it is unlikely to be porous.

[0045]

EXAMPLES Hereinafter, the composition of the present invention will be specifically described based on examples, but the present invention is not limited thereto.

The raw materials and evaluation methods used in the examples and comparative examples are summarized below.

SBR: styrene-butadiene rubber, SBR 1502 manufactured by Sumitomo Chemical Co., Ltd. (styrene unit content: 23.5%) EXXPRO: bromide of isobutylene / p-methylstyrene copolymer, EXXPRO manufactured by Exxon 90-
10 Silica A: Silica, Ultrasil manufactured by Degussa
VN3 Silica B: Silica treated with a coupling agent, precoupled silica COUPSIL 8108 manufactured by Degussa (UI
Trasil VN3 heat-treated using 8% of Si69) Silane coupling agent: Si69 (chemical name: 3,3'-bis (triethoxysilylpropyl) tetrasulfide) manufactured by Degussa Aroma oil: Idemitsu Kosan ( Diana Process A
H40 Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Stearic acid manufactured by NOF Corporation Oxidized flower: Mitsui Kinzoku Mining Co., Ltd. Sulfur: powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator CZ: Noxeller CZ manufactured by Ouchi Shinko Chemical Co., Ltd. (chemical name: N-cyclohexyl-2-benzothiazolyl sulfene) Amide) Vulcanization accelerator DPG: Succinol D (chemical name: 1,3-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

(Degree of Porosity) The degree of porousness of the vulcanized tire was visually observed (length: 10 mm, width: 10 mm, thickness: 4 m)
m range) on a 5-point scale. 1: 10 or more pores with a bubble diameter of 1 mm or more 2: 1 or more and less than 10 pores with a bubble diameter of 1 mm or more 3: No porous with a diameter of 1 mm or more, and 10 or more porous with a bubble diameter of 0.1 mm or more 4: No porosity of 1 mm or more, 1 to less than 10 pores with a bubble diameter of 0.1 mm or more 5: Almost no porosity

Examples 1 and 2 and Comparative Example 1 A mixture of the components shown in Table 1 (excluding sulfur and the vulcanization accelerator) in the proportions shown in Table 1 was mixed using a BR type Banbury mixer to obtain a mixture. Kneaded at ~ 180 ° C for 3-5 minutes. To the resulting kneaded material, sulfur and a vulcanization accelerator were added at the ratios shown in Table 1, and 50
The composition kneaded at 10 ° C. for 10 minutes was press-vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized rubber, which was subjected to the evaluation. Table 1 shows the results.

[0050]

[Table 1]

From Table 1, it can be seen that, in Comparative Example 1 in which silica and a silane coupling agent were reacted in a rubber kneading step, a porous state was apt to occur in the vulcanization step, but in Example 1 in which precoupled silica was used, It turns out that it is hard to become porous.

It can be seen that even with the use of precoupled silica, Example 2 in which the amount of EXXPRO 90-10, which has excellent air permeation resistance, was increased, became more porous than in Example 1.

[0053]

The use of the composition of the present invention makes it less likely to become porous in the vulcanization step than conventional products, and a non-porous tire can be obtained.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shintaro Sugiyama 1-27-11 Aokicho, Toyota-shi, Aichi F-term (reference) 4J002 AC01X AC02X AC03X AC06X AC07X AC08X AC09X BB24W BC111 DJ016 FB096 FB116 FB146 FB156

Claims (2)

[Claims] 1. A silane cup based on 100 parts by weight of a total of at least 5 to 75 parts by weight of at least one kind of a halogenated butyl rubber and a halide of an isobutylene / p-methylstyrene copolymer and 25 to 95 parts by weight of a diene rubber. A rubber composition for a tread, comprising 40 to 150 parts by weight of silica treated with a ring agent. 2. The rubber composition according to claim 1, wherein the silica treated with the silane coupling agent is obtained by previously heat-treating silica and a silane coupling agent containing sulfur.