JPH10237223A - Rubber composition and vulcanized rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. which is excellent in rolling resistance, electrical conductivity, and external appearance by compounding a diene rubber with a surface-treated silica which is prepd. by causing silica to carry a mixture prepd. by mixing a mixture comprising diester compds. derived from adipic or phthalic acid with a compd. contg. an alkali or alkaline earth metal salt. SOLUTION: An example of the diene rubber (A) is a styrene-butadiene copolymer rubber. The diester compd. (B) is represented by formula I or II (wherein Y is a 2-22C carboxylic acid residue; R1 is H or 1-15C alkyl; R2 and R3 are each 1-15C alkyl or alkenyl; R4 is H or methyl; Z is 2-4C alkylene; J is 1-30; K is 1-4; and (p) is 2-20). An example of the metal-salt-contg. compd. (C) is LiClO4 . Pref., silica used has a DBA adsorption of 100-400mmol/kg, a BET specific surface area of 50-300m<2> /g, and a pH of 5-12. The compounding ratio by wt. of (B+C)/A and (B+C)/D are (5/100)-(500/100) and (60/40)-(5-95), respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition and a vulcanized rubber composition. More specifically, the present invention relates to a rubber composition containing a diene rubber as a rubber component, which has excellent rolling resistance, excellent electrical conductivity due to low electric resistance, and can suppress the occurrence of bleed. The present invention relates to a rubber composition and a vulcanized rubber composition having excellent appearance.

[0002]

2. Description of the Related Art Styrene-butadiene copolymer rubber (S
Diene rubbers represented by BR) are widely used as rubbers for automobile tire treads because of their excellent mechanical properties and abrasion resistance. One of the important conditions required for rubber for an automobile tire tread is that the rolling resistance is low. This is achieved by keeping rolling resistance low
This is because fuel economy performance can be improved. As a technique for keeping the rolling resistance of tire rubber low, a method of blending silica is known. However, according to this method, although the rolling resistance is improved, there is a problem that the electrical resistance value of the rubber increases. If the electrical resistance of the rubber is high, static electricity will accumulate during driving, causing the danger of sparks and causing malfunctions of radio systems such as car radios and car navigation, causing various inconveniences. is there.

[0003]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a rubber composition containing a diene rubber as a rubber component, which has excellent rolling resistance and electric resistance. An object of the present invention is to provide a rubber composition and a vulcanized rubber composition which are excellent in conductivity because they are low and can suppress generation of bleed and thus have excellent appearance.

[0004]

That is, one aspect of the present invention relates to a rubber composition containing the following components (A) and (B). (A): a diene rubber (B): a mixture of a compound represented by the following general formula (1) and / or a compound represented by the following general formula (2):
Surface-treated silica obtained by supporting a compound obtained by compounding an alkali metal salt-containing compound and / or an alkaline earth metal salt-containing compound on silica (In the formula (1), Y is a group having 2 to 2 carbon atoms which may have a substituent.
2 represents an aliphatic, alicyclic or aromatic carboxylic acid residue or a carboxylic acid residue of an epoxycyclohexane ring,
R ₁ represents a hydrogen atom or a linear or branched alkyl group having 1 to 15 carbon atoms; Z represents an alkylene group having 2 to 4 carbon atoms; J represents a number of 1 to 30; Represents an integer. In the formula (2), R ₂ and R ₃ represent an alkyl group or an alkenyl group having 1 to 15 carbon atoms, R ₄ represents a hydrogen atom or a methyl group, and p represents an integer of 2 to 20. )

[0005] Another aspect of the present invention relates to a vulcanized rubber composition obtained by vulcanizing the above rubber composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The component (A) of the present invention is a diene rubber.

Examples of the diene rubber include natural rubber, polybutadiene rubber, polyisoprene rubber, butadiene-isoprene copolymer rubber, and styrene-butadiene copolymer rubber.

When used for an automobile tire tread rubber, a styrene-butadiene copolymer rubber is preferred from the viewpoint of mechanical properties and abrasion resistance.
That is, from the viewpoint of fuel economy, a styrene-butadiene copolymer rubber obtained by a solution polymerization method is preferable.

[0009] In addition to the rubber component (A) of the present invention, various synthetic rubbers can be blended.

The component (B) of the present invention has the general formula (1)
A compound obtained by mixing an alkali metal salt-containing compound and / or an alkaline earth metal salt-containing compound with a compound represented by the formula Is a surface-treated silica obtained by being supported on a silica gel.

A preferred specific example of the compound represented by the general formula (1) is bis [2- (2-butoxyethoxy)
Ethyl] adipate, bis (2-butoxyethyl) phthalate, diester compounds derived from polyethylene glycol having a molecular weight of 100 to 2,000 and adipic acid, and diester compounds derived from polyethylene glycol having a molecular weight of 100 to 2,000 and phthalic acid. it can. The molecular weight of the polyethylene glycol is preferably in the range of 100 to 2,000.

Preferred examples of the compound represented by the general formula (2) include triethylene glycol dioctoate, tetraethylene glycol dioctoate, heptaethylene glycol dioctoate, and triethylene glycol di-2-ethyl. Butyrate and tetraethylene glycol-di-2-ethylhexoate.

A mixture of the compound represented by the general formula (1) and / or the compound represented by the general formula (2) may contain a compound represented by the following general formula (3). .

[0014]

(In the formula (3), L and M each represent 1 or 2, N and O each represent an integer of 1 to 3, and X has 2 to 4 carbon atoms.
And R ₅ and R ₆ each represent a linear or branched alkyl group having 1 to 8 carbon atoms. )

A preferred specific example of the compound represented by the general formula (3) is bis [2- (2-butoxyethoxy)
[Ethyl] thiodipropionate and bis (2-butoxyethyl) thiodipropionate.

As the cation site of the alkali metal salt or alkaline earth metal salt of the component (B), Li, Na, K,
Mg, Ba, Ca, etc. can be mentioned, and Cl, Br, I, BF ₄ , PF ₄ , Cl
O ₄ , NO ₃ , CO _{3 and the} like can be mentioned.

Examples of the compound containing an alkali metal salt or the compound containing an alkaline earth metal salt include LiClO ₄ , Ba (C
lO ₄ ) ₂ , LiI and MgCO ₃ are preferred.

An alkali metal salt-containing compound and / or an alkaline earth metal salt-containing compound are added to a mixture of the compound represented by the general formula (1) and / or the compound represented by the general formula (2). In this case, the compounding ratio is the total of the alkali metal salt-containing compound and the alkaline earth metal salt-containing compound per 100 parts by weight of the total weight of the compound represented by the general formula (1) and the compound represented by the general formula (2) Amount 0.01-3
0 parts by weight, more preferably 0.1 to
20 parts by weight. When the total amount of the alkali metal salt-containing compound and the alkaline earth metal salt-containing compound is too small, the electric resistance does not sufficiently decrease, and the antistatic effect may be poor. The effect of lowering the electric resistance value with respect to the additional amount of the metal salt-containing compound and the alkaline earth metal salt-containing compound may level off and become uneconomical.

In order to obtain the compound in the component (B), the alkali metal salt-containing compound is added to the mixture of the compound represented by the general formula (1) and / or the compound represented by the general formula (2). And / or an alkaline earth metal salt-containing compound may be blended.

The weight ratio of the blend / silica in the component (B) is preferably from 60/40 to 5/95, and more preferably from 55/45 to 10/90. If the ratio is too small, the conductivity may be insufficient.If the ratio is too large, the compound cannot be supported on the surface of silica, and the compound bleeds on the surface of the obtained vulcanized rubber. May be.

The silica used in the present invention is not particularly limited, but has a DBA (dibutylamine) adsorption amount of 10
0 to 400 mmol / kg and a BET specific surface area of 5
Powdered silica having a pH of 0 to 300 m ² / g and a pH of 5 to 12 is preferred.

As a method for obtaining the surface-treated silica as the component (B) of the present invention, for example, the above-mentioned compound is added to silica as a carrier using a Henschel mixer, a tumbling drum, a super mixer, a ball mill, an atomizer or the like. What is necessary is just to carry.

In the rubber composition of the present invention, the content of the component (B) per 100 parts by weight of the component (A) is from 10 to 5%.
00 parts by weight, more preferably 10 parts by weight.
４００400 parts by weight. If the amount of the component (B) is too small, the conductivity may be insufficient. On the other hand, if the amount of the component (B) is too large, the compound viscosity may increase and the processability may be poor. When various synthetic rubbers other than the component (A) are used, the amount of the component (A) is based on the total amount including the amounts of the various synthetic rubbers.

The rubber composition of the present invention preferably contains 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, of the silane coupling agent (C) per 100 parts by weight of the component (A). is there. If the amount of the component (C) is too small, the processability and the mechanical strength of the vulcanizate deteriorate, and if the amount of the component (C) is too large, the production cost increases.

Specific examples of component (C) include bis- (trimethoxysilylmethyl) disulfide, bis- (2-trimethoxysilylethyl) disulfide, and bis- (2-
Trimethoxysilylethyl) tetrasulfide, bis-
(2-trimethoxysilylethyl) pentasulfide,
Bis- (2-trimethoxysilylethyl) octasulfide, bis- (3-trimethoxysilylpropyl) disulfide, bis- (3-trimethoxysilylpropyl)
Trisulfide, bis- (3-trimethoxysilylpropyl) tetrasulfide, bis- (3-trimethoxysilylpropyl) pentasulfide, bis- (3-trimethoxysilylpropyl) octasulfide, bis- (4
-Trimethoxysilylbutyl) tetrasulfide, 1-
Mercapto-2-trimethoxysilylethane, 1-mercapto-3-trimethoxysilylpropane, 1-mercapto-4-trimethoxysilylbutane, 1,2-epoxy-3-trimethoxysilylpropane, 1,2-epoxy- 4-trimethoxysilylbutane, 3-trimethoxysilyl-1-propene, 4-trimethoxysilyl-1-
Butene, 1-dimethylamino-3-trimethoxysilylpropane, 1-dimethylamino-4-trimethoxysilylbutane, vinyltrimethoxysilane, vinyl-tris (2-methoxyethoxy) silane, γ-methacryloxypropyl-trimethoxy Examples include silane, γ-mercaptopropyl-trimethoxysilane, γ-aminopropyl-trimethoxysilane, and compounds in which the methoxy group of the above compound is substituted with an ethoxy group.

Among them, particularly preferred are bis- (3-triethoxysilylpropyl) trisulfide, bis- (3-triethoxysilylpropyl) tetrasulfide, bis- (3-triethoxysilylpropyl) pentasulfide and γ-mercaptopropyl-trimethoxysilane.

The most important feature of the present invention is that the component (B) is used. Without using the present invention, when only silica is used, the electric resistance cannot be sufficiently reduced. When the compound of the present invention is used without being supported on silica, bleeding occurs and the appearance of the vulcanized rubber product is inferior.

The method for obtaining the rubber composition of the present invention includes:
For example, the following method can be used. That is, the components (A) and (B) of the present invention, and if necessary, reinforcing materials such as silica and carbon black, softeners such as process oil, activators such as stearic acid, and additives such as zinc oxide. A compound is obtained by kneading a sulfur promoting accelerator, various silane coupling agents, and the like using a Banbury mixer, a kneader, or the like. Next, a vulcanizing agent, a vulcanization accelerator and the like are kneaded with the compound using an open roll, a kneader or the like to obtain a rubber composition before vulcanization. Here, sulfur and various organic peroxides are used as the vulcanizing agent. The rubber composition before vulcanization is vulcanized under normal conditions to become a vulcanized rubber composition.

The rubber composition and the vulcanized rubber composition of the present invention have the above-mentioned characteristics and can be optimally used particularly for an automobile tire tread. It can also be widely used in the field of parts, electric parts, etc., such as rolls, belts, electric parts sealing materials, antistatic mats, conductive sheets and the like.

[0031]

Next, the present invention will be described by way of examples.

Examples 1 to 5 and Comparative Example 1 Styrene obtained by a solution polymerization method as component (A)
Butadiene copolymer rubber (styrene unit / vinyl unit =
(29/49 wt% /%) 100 parts by weight of the components shown in Table 1 and 6.4 parts by weight of component (C) silane coupling agent Si69 (manufactured by Degussa) as a common formulation;
6.4 parts by weight of carbon black, 1.5 parts by weight of Sunnock N (Antiaging agent manufactured by Ouchi Shinko Chemical Co., Ltd.), Antigen 3C
(Anti-aging agent manufactured by Sumitomo Chemical Co., Ltd.) 1.5 parts by weight, 2 parts by weight of zinc white and 2 parts by weight of stearic acid were kneaded using a Banbury mixer to obtain a compound.
Next, 1 part by weight of Succinol CZ (vulcanization accelerator manufactured by Sumitomo Chemical Co., Ltd.), 1 part by weight of Succinol D (vulcanization accelerator manufactured by Sumitomo Chemical Co., Ltd.) and 1.4 parts by weight of sulfur are added and kneaded to the compound. Thus, a rubber composition was obtained. The obtained rubber composition was press-vulcanized under the conditions of 160 ° C. × 45 minutes to obtain a vulcanized rubber composition. The vulcanized rubber composition was evaluated according to the following method. The results are shown in Tables 1 and 2.

Evaluation Items and Evaluation Methods (1) Tensile properties: JIS K
It was evaluated according to 6251. A dumbbell-shaped No. 3 test piece was used. (2) Tear strength: Evaluated according to JIS K6252. The test piece used was an angle-type sample without cutting. (3) Abrasion resistance (abrasion loss amount): Measured according to JIS K6264 using an Akron abrasion tester. (4) Rolling resistance (tan δ) index: Measured using a rheograph solid L1R manufactured by Toyo Seiki Co., Ltd. under the conditions of a frequency of 10 Hz, an initial strain of 10%, an amplitude of ± 0.25%, and a heating rate of 2 ° C./min. Thus, a tan δ temperature dispersion curve was obtained, and a tan δ value at 60 ° C. was determined from this curve. Next, the tan δ values of the examples and the comparative examples were represented by indices with the comparative example 1 being 100. The smaller the index, the lower the rolling resistance. (5) Electric resistance: JIS K for vulcanized rubber composition
The volume resistivity was measured at an applied voltage of 500 V by a method based on 6911. (6) Surface bleed: The vulcanized rubber sheet was allowed to stand at room temperature for one week, and the presence or absence of bleed on the surface was visually observed, and evaluated by （(good: no bleed) and × (poor: bleed).

The following can be understood from the results. Examples satisfying the conditions of the present invention have sufficiently low electric resistance. On the other hand, Comparative Example 1 using only silica without using the component (B) of the present invention has a high electric resistance value.

[0035]

[Table 1] --------------------------------------------------------------------------- Example 1 2 3 4 Formulation * 1 wt * * * * * * * * * * * * * * * *--------------------------------------------------------------- (B1) 0 40.4 0 60.6 (B2) 67.3 0 101.3 0 (B3) 0 0 0 0 Silica 21.2 48.4 0 37.9 Oil 40.0 40.0 40.0 40.0 Evaluation results Tensile properties M300 kgf / cm ² 138 128 122 122 Tb kgf / cm ² 258 249 241 241 Eb% 500 520 520 520 Hs JIS-A 70 69 72 71 Tear strength kgf / cm 59 58 59 56 Wear resistance Loss mg / 1000 times 306 327 333 360 Rolling resistance index 101 104 107 105 Volume specific electricity Resistance voltage (500V) Ωcm 1.8 × 10 ¹¹ 1.1 × 10 ¹¹ 2.9 × 10 ¹⁰ 2.9 × 10 ¹⁰ Surface bleed ○ ○ ○ ○ −−−−−−−−−−−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−

[0036]

Table 2-------------------------------------------------------------------------------------------Example ) 0 0 (B3) 98.5 0 Silica 0 78.4 Oil 40.0 50.0 Evaluation results Tensile properties M300 kgf / cm ² 153 120 Tb kgf / cm ² 239 245 Eb% 470 510 Hs JIS-A 73 68 Tear strength kgf / cm 55 56 Resistance Abrasion loss mg / 1000 times 391 283 Rolling resistance index 83 100 Volume specific electric resistance Voltage (500V) Ω ・ cm 1.6 × 10 ⁹ 2.1 × 10 ¹⁴ Surface bleed ○ ○ −−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−

* 1 Formulation (B1): bis [2- (2-butoxyethoxy) ethyl] adipate which is a compound represented by the general formula (1) and bis which is a compound represented by the general formula (3) [2- (2
-Butoxyethoxy) ethyl] thiodipropionate (compound represented by general formula (1) / general formula (3)
(Weight ratio of the compound represented by the formula: 100/2), a surface-treated silica obtained by supporting a compound obtained by mixing LiClO ₄ being an alkali metal salt-containing compound on powdered silica (formulation (B2): Bis [2- (2-butoxyethoxy) ethyl] adipate, which is a compound represented by the general formula (1), and a compound represented by the general formula (3) The compound bis [2- (2
-Butoxyethoxy) ethyl] thiodipropionate (compound represented by general formula (1) / general formula (3)
Surface-treated silica obtained by supporting a compound obtained by mixing LiClO ₄ that is an alkali metal salt-containing compound with respect to the weight ratio of the compound represented by (B3): an alkali metal salt-containing compound with respect to a diester compound derived from polyethylene glycol having a molecular weight of 600, which is a compound represented by the general formula (1), and adipic acid. Surface-treated silica obtained by supporting a blend obtained by blending LiClO ₄ which is a silica powder (weight ratio of blend / silica = 15/85). Silica: Ultrasil VN3G (manufactured by United Silica)・ Oil: X-140 (manufactured by Kyodo Sekiyu)

[0038]

As described above, according to the present invention, a rubber composition containing a diene rubber as a rubber component, having excellent rolling resistance, low electric resistance, excellent conductivity, and excellent bleeding Since the generation can be suppressed, a rubber composition and a vulcanized rubber composition having excellent appearance can be provided.

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification code FI C09C 1/60 C09C 1/60 (72) Inventor Yoshito Hirano 2-10-6 Miyanishi, Harima-cho, Kako-gun, Hyogo Sansan Kako Co., Ltd. In company

Claims (11)

[Claims] 1. A rubber composition containing the following components (A) and (B). (A): a diene rubber (B): a mixture of a compound represented by the following general formula (1) and / or a compound represented by the following general formula (2):
Surface-treated silica obtained by supporting a compound obtained by compounding an alkali metal salt-containing compound and / or an alkaline earth metal salt-containing compound on silica (In the formula (1), Y is a group having 2 to 2 carbon atoms which may have a substituent.
2 represents an aliphatic, alicyclic or aromatic carboxylic acid residue or a carboxylic acid residue of an epoxycyclohexane ring,
R ₁ represents a hydrogen atom or a linear or branched alkyl group having 1 to 15 carbon atoms; Z represents an alkylene group having 2 to 4 carbon atoms; J represents a number of 1 to 30; Represents an integer. In the formula (2), R ₂ and R ₃ represent an alkyl group or an alkenyl group having 1 to 15 carbon atoms, R ₄ represents a hydrogen atom or a methyl group, and p represents an integer of 2 to 20. ) 2. The rubber composition according to claim 1, wherein the component (A) is a diene rubber obtained by a solution polymerization method. 3. The rubber composition according to claim 1, wherein the compound represented by the general formula (1) is bis [2- (2-butoxyethoxy) ethyl] adipate or bis (2-butoxyethyl) phthalate. 4. The compound represented by the general formula (1) is a diester compound derived from polyethylene glycol having a molecular weight of 100 to 2,000 and adipic acid, or having a molecular weight of 10
The rubber composition according to claim 1, which is a diester compound derived from 0 to 2000 polyethylene glycol and phthalic acid. 5. The rubber composition according to claim 1, wherein the compound represented by the general formula (2) is triethylene glycol dioctoate, tetraethylene glycol dioctoate, or heptaethylene glycol dioctoate. 6. The cation site of the alkali metal salt or alkaline earth metal salt of the component (B) is Li, Na, K, Mg,
Ba or Ca, wherein the anion site is Cl, Br, I,
_{BF 4, PF 4, ClO 4} , NO 3 or CO ₃ in a claim 1 rubber composition. 7. The method according to claim 1, wherein the compound containing an alkali metal salt or the compound containing an alkaline earth metal salt is LiClO ₄ , Ba (ClO
₄ ) The rubber composition according to claim 1, which is ₂ , LiI or MgCO ₃ . 8. The rubber composition according to claim 1, wherein the weight ratio of the compound / silica in the component (B) is from 60/40 to 5/95. 9. (B) per 100 parts by weight of (A) component
The rubber composition according to claim 1, wherein the content of the component is 10 to 500 parts by weight. 10. A vulcanized rubber composition obtained by vulcanizing the rubber composition according to claim 1. 11. The vulcanized rubber composition according to claim 10, which is used for an automobile tire tread.