JP2002265676A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which can improve a rolling resistance characteristic and a wet grip performance without deteriorating processability and abrasion resistance. SOLUTION: This rubber composition comprises 100 pts.wt. of a dienic rubber, 5 to 100 pts.wt. of silica, and further a silane coupling agent and a polyoxyalkylene glycol compound having an alkoxyl group at the terminal in amounts of 1 to 20 wt.% and 1 to 25 wt.%, respectively based on the weight of the silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low heat generating property (rolling resistance characteristic) without lowering workability and wear resistance.
The present invention relates to a rubber composition capable of improving wet grip performance.

[0002]

2. Description of the Related Art In recent years, the characteristics required for automobile tires are various, such as low fuel consumption, driving stability, wear resistance, and riding comfort. Various improvements have been made to improve these performances. . Among these performances, the grip performance and the rolling resistance characteristics of the tire are all characteristics relating to the hysteresis loss of the rubber. Generally, when the hysteresis loss is increased, the grip force is increased and the braking performance is improved, but the rolling resistance is increased and the fuel efficiency is increased. As described above, the grip performance and the rolling resistance characteristic have an opposite relationship.

[0003] Various rubber compositions for tires have been proposed in order to satisfy both properties at the same time. For example, in a rubber composition for a tire, particularly, since a polymer and carbon black greatly affect both properties, when a styrene-butadiene copolymer is used as a polymer, the content of bound styrene, 1,2- By appropriately selecting the bound butadiene unit content, both the rolling resistance characteristics and the grip performance are improved. On the other hand, with respect to carbon black, a type of carbon black in which the activity of the carbon black particle surface is improved has been developed and has been effective.

[0004] Further, many methods using silica and a silane coupling agent for the purpose of reducing heat generation have been reported. The silane coupling agent binds to the silanol groups on the silica surface to prevent aggregation of the silica and improve processability, while at the same time reducing the rolling resistance by chemically bonding the silica and polymer to the silane coupling agent. It is believed that. However, there is a problem that a reduction in wear resistance cannot be avoided even by using a silane coupling agent.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to improve rolling resistance and wet grip performance without deteriorating workability and wear resistance.

[0006]

As a result of intensive studies to improve the above-mentioned problems, the use of a polyoxyalkylene glycol compound having an alkoxysilyl group at the terminal enables the processability and abrasion resistance to be reduced. A method was developed to satisfy rolling resistance characteristics and wet grip performance.

[0007] That is, the present invention relates to 100 parts by weight of natural rubber and / or diene-based synthetic rubber, and silica 5
-100 parts by weight, and based on the weight of silica,
The present invention relates to a rubber composition containing 1 to 20% by weight of a silane coupling agent and 1 to 25% by weight of a polyoxyalkylene glycol compound represented by the following general formula (1) or (2).

[0008]

Embedded image

(Wherein, R ¹ is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group, which may be the same or different from each other. R ² is a methylene group, ethylene R ³ is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group having 1 to 22 carbon atoms, and may be the same or different from each other. Or an aryl group. M is an integer of 1 to 9, and n is an integer of 100 or less.)

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0011] The rubber composition of the present invention comprises:
Contains natural rubber (NR) and / or diene-based synthetic rubber. Examples of the diene-based synthetic rubber include styrene-butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), butyl rubber (IIR), and acrylonitrile- Butadiene rubber (NBR) and the like. The rubber composition of the present invention,
As the rubber component, one or more NR and / or diene-based synthetic rubbers can be included.

Next, the rubber composition of the present invention contains silica. The compounding amount of silica is 5 to 100 parts by weight, preferably 10 to 85 parts by weight, based on 100 parts by weight of the rubber component. If the amount of silica is less than 5 parts by weight, the reinforcing effect is small, and if it exceeds 100 parts by weight, workability is reduced.
From the viewpoint of low heat generation and workability, the amount of silica is more preferably 20 to 65 parts by weight.

[0013] Nitrogen adsorption specific surface area of silica (N ₂ SA)
Is from 100 to 300 m ² / g, and further from 120 to 280
It is preferably m ² / g. N ₂ SA is 100 m ² /
If it is less than g, the reinforcing effect is small, and if it exceeds 300 m ² / g, the dispersibility decreases, and the heat generation of the rubber composition increases.

[0014] The rubber composition of the present invention contains a silane coupling agent for strengthening the bond between the filler and the rubber component and improving the abrasion resistance. As a silane coupling agent,
Any silane coupling agent conventionally used in combination with a silica filler can be suitably used. In particular,
Silane coupling agents such as sulfide, mercapto, vinyl, amino, glycidoxy, nitro, and chloro can be used.

Examples of the sulfide-based silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (3-trimethoxysilylpropyl) tetrasulfide. (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3- Trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxy Silylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzothiazole Examples thereof include tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide.

The mercapto-based silane coupling agent includes 3-mercaptopropyltrimethoxysilane, 3
-Mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and the like.

Examples of the vinyl silane coupling agent include vinyl triethoxy silane and vinyl trimethoxy silane.

Examples of the amino-based silane coupling agent include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, and 3- (2-aminoethyl ) Aminopropyltrimethoxysilane and the like.

As glycidoxy silane coupling agents, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, γ-
Glycidoxypropylmethyldimethoxysilane and the like can be mentioned.

Examples of the nitro silane coupling agent include 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.

Examples of the chloro-based silane coupling agent include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane.

Among these, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, and 3-mercaptopropyltrimethoxysilane are preferred in terms of both the effect of adding the coupling agent and the cost. Etc. are preferably used. The silane coupling agent may be used alone or in combination of two or more.

The amount of the silane coupling agent is as follows:
The amount is preferably 1 to 20% by weight based on the weight of the silica. If the amount of the silane coupling agent is less than 1% by weight, the effect of adding the silane coupling agent is not sufficient. If the amount is more than 20% by weight, the coupling effect is not obtained despite the increase in cost, and the reinforcing property, It is not preferable because abrasion resistance is reduced. From the viewpoint of the dispersing effect and the coupling effect, the amount of the silane coupling agent is preferably 2 to 15% by weight.

The polyoxyalkylene glycol compound used in the present invention has an alkoxysilyl group at a terminal and is represented by the following general formula (1) or (2). Since the polyoxyalkylene glycol compound used in the present invention has an alkoxysilyl group at the terminal, it reacts with a silanol group on the silica surface and can prevent aggregation of silica. Also, by having an oxyalkylene chain,
It adsorbs to silica, carbon black and other fillers, prevents aggregation of the fillers, and increases the interaction between the rubber and the fillers and fillers.

[0025]

Embedded image

In equations (1) and (2), R
¹ is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group, all of which may be the same or different from each other. R ¹ is particularly preferably an alkyl group having 1 to 3 carbon atoms, since it easily interacts with silica.

R ² is a methylene group, an ethylene group, a propylene group or a tetramethylene group, all of which may be the same or different. R ³ has 1 to 1 carbon atoms
22 straight-chain or branched saturated or unsaturated aliphatic hydrocarbon groups or aryl groups.

M is an integer of 1 to 9, preferably 2 to 6. n is an integer of 100 or less, preferably 6 to 95. When n exceeds 100, the dispersing effect becomes insufficient,
If it is less than 6, the volatility of the polyoxyalkylene glycol compound is high, and the workability is reduced.

The polyoxyalkylene glycol compound represented by the formula (1) is, for example, a polyoxyalkylene glycol and an isocyanate compound ((R ¹ O) ₃ —Si— (CH ₂ ) corresponding to OR ¹ in the formula (1). _m- N = C =
O) to produce the compound.

The polyoxyalkylene glycol compound represented by the formula (2) is, for example, a polyoxyalkyl ether and an isocyanate compound ((R ₁ O) ₃ —Si— (CH ₂ ) corresponding to OR ¹ in the formula ( ₂ ). _m- N = C = O)
Can be produced by reacting

The amount of the polyoxyalkylene glycol compound is 1 to 25% by weight based on the weight of the silica. If the compounding amount of the polyoxyalkylene glycol compound is less than 1% by weight, the effect of adding the polyoxyalkylene glycol compound is not sufficient, and if it exceeds 25% by weight, a low heat-generating effect cannot be obtained despite the increase in cost. . From the viewpoint of low heat generation, the compounding amount of the polyoxyalkylene glycol compound is more preferably 2 to 20% by weight.

In the rubber composition of the present invention, carbon black or the like can be used as a filler in addition to the silica.
The compounding amount of carbon black contained in the rubber composition of the present invention is preferably 80 parts by weight or less based on 100 parts by weight of the rubber component. If the amount of the carbon black exceeds 80 parts by weight, the heat generation tends to increase. The amount of carbon black is more preferably 25 to 60 parts by weight from the viewpoint of reinforcing properties and low heat generation.

Examples of the carbon black that can be used in the present invention include, but are not particularly limited to, HAF, ISAF, and SAF.

The rubber composition of the present invention may further contain a softening agent, an antioxidant, a vulcanizing agent, if necessary, in addition to the rubber component, silica, silane coupling agent, and polyoxyalkylene glycol compound. Compounding agents used in the ordinary rubber industry, such as vulcanization accelerators and vulcanization accelerators, can be appropriately compounded.

The rubber composition of the present invention is excellent in processability, abrasion resistance, rolling resistance and wet grip performance, and is suitable for tire members such as tire treads, carcass, belts, sidewalls, bead portions, vibration damping, etc. It can be suitably used for rubber, belts, hoses, and various other industrial rubbers.

[0036]

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

Examples 1-4 and Comparative Examples 1-2 <Description of Various Chemicals> Diene-based synthetic rubber: SBR manufactured by JSR Corporation
1502 (styrene-butadiene copolymer, styrene unit content: 23.5% by weight, 1,2-bonded butadiene unit content: 18% by weight) Silica: Ultrasil VN3 (N ₂ S, manufactured by Degussa)
A: 210 m ² / g) Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa Antioxidant: Nocrack 6 manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) Stearic acid: Stearic acid manufactured by NOF Corporation Zinc oxide: Zinc flower No. 1 manufactured by Mitsui Kinzoku Kogyo Sulfur: powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator TBBS: Noxeller NS (Ouchi Shinko Chemical Industry Co., Ltd.) (N-tert-butyl-2-benzothiazylsulfenamide) Vulcanization accelerator DPG : Noxeller D (Ouchi Shinko Chemical Industry Co., Ltd.) (N, N'-diphenylguanidine) Polyoxyalkylene glycol compound: Examples 1-4
In the general formula (1), R ¹ , R ² , m,
A compound having n or a compound having R ¹ , R ² , R ³ , m, and n shown in Table 1 in the general formula (2) was used. In Comparative Example 2, polyethylene glycol having a number average molecular weight of 400 (PEG400 manufactured by Sanyo Chemical Industries, Ltd.) was used.

[0038]

[Table 1]

<Production Method of Polyoxyalkylene Glycol Compound> (Compound) In 2-butanone, 50 g of polyethylene glycol having a number average molecular weight of 600 and 41.2 g of 3-isocyanatopropyltriethoxysilane were reacted at 60 ° C. for 3 hours. A compound was obtained.

(Compound) In 2-butanone, 50 g of polyethylene glycol having a number average molecular weight of 1,000 and 24.7 g of 3-isocyanatopropyltriethoxysilane were reacted at 60 ° C. for 3 hours to obtain a compound.

(Compound) In 2-butanone, 50 g of UNIOX M-400 (manufactured by NOF Corporation) and 60 g of 3-isocyanatopropyltriethoxysilane were added at 60 ° C.
For 3 hours to obtain a compound.

<Compounding Formula> According to the compounding formula shown in Table 2, the mixture was kneaded and compounded to obtain various test rubber compositions. These compounds were press-vulcanized at 170 ° C. for 20 minutes to obtain vulcanized products, which were tested for the following properties.

[0043]

[Table 2]

<Test Method> (Workability) Measured at 130 ° C. according to the Mooney viscosity measurement method specified in JIS K6300. The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 1 was set to 100 and expressed as an index by the following formula (Mooney viscosity index). The larger the index, the lower the Mooney viscosity and the better the processability. (Mooney viscosity index) = (ML _{1 + 4} of Comparative Example 1) ÷ (ML _{1 + 4 of} each formulation) × 100

(Abrasion Test) Lambourn Abrasion Tester A wear test was performed using a Lambourn abrasion tester.
At that time, the measurement conditions were as follows: temperature 20 ° C., slip rate 20%,
The test time was 5 minutes. The volume loss of each compound was calculated, and the loss amount in Comparative Example 1 was set to 100, and the index was expressed by the following formula (wear index). The larger the index, the better the wear resistance. (Abrasion index) = (Loss of Comparative Example 1) ÷ (Loss of each compound) × 100

(Rolling resistance index) Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho), a temperature of 7
The measurement was performed under the conditions of 0 ° C., an initial strain of 10%, and a dynamic strain of 2%. The loss tangent (tan δ) of each compound was measured, and the tan δ of Comparative Example 1 was set to 100, and was expressed as an index by the following formula. The higher the index, the better the rolling resistance characteristics. (Rolling resistance index) = (tan δ of Comparative Example 1) ÷ (tan δ of each formulation) × 100

(Wet skid test) ASTM E3 using a portable squid tester manufactured by Stanley
It was measured according to the method of 03-83, and was indicated as an index by the following formula. The higher the index, the better the wet skid performance. (Wet skid index) = (numerical value of each formulation) / (numerical value of comparative example 1) × 100

<Test Results> The results are shown in Table 3. Examples 1 to 4 in which a specific polyalkylene glycol compound was blended
As compared with Comparative Example 2 in which polyethylene glycol was blended, rolling resistance characteristics and wet skid performance could be improved without lowering workability and abrasion resistance.

[0049]

[Table 3]

[0050]

According to the rubber composition of the present invention, rolling resistance characteristics and wet grip performance can be improved without lowering workability and wear resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 71:02) (C08L 7/00 (C08L 7/00 71:02) 71:02) C08K 5/54

Claims (1)

[Claims] 1 to 100 parts by weight of a natural rubber and / or a diene-based synthetic rubber, containing 5 to 100 parts by weight of silica, 1 to 20% by weight of a silane coupling agent based on the weight of silica, and Equation (1) or (2)
Polyoxyalkylene glycol compound 1 represented by
A rubber composition containing ２５25% by weight. Embedded image (Wherein, R ¹ is an alkyl group having 1 to 6 carbon atoms, or
A cycloalkyl group, which may be the same or different from each other. R ² is a methylene group, an ethylene group, a propylene group or a tetramethylene group, all of which may be the same or different from each other. R ³ is
It is a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 1 to 22 carbon atoms, or an aryl group. m
Is an integer of 1 to 9, and n is an integer of 100 or less. )