JP2001192454A - Organopolysiloxane, compounding agent for rubber, rubber composition containing the agent and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organopolysiloxane having improved dispersibility of silica, effective for improving various physical properties of a rubber composition and suitable for a rubber composition for tire tread. SOLUTION: The objective organopolysiloxane has a number-average molecular weight of 600-300,000 and contains a structural unit expressed by general formula R1-SiZ13 (R1 is a 1-18C substituted or non-substituted hydrocarbon group; Z1 is a group selected from OX group and siloxane residue; and at least one of the Z1 group is siloxane residue) and a structural unit expressed by general formula Z2p(CH3)(3-p)Si-R2-Sm-R2-Si-(CH3)(3-p)Z2p (R2 is a 1-10C bivalent hydrocarbon group; Z2 is a group selected from OX group and siloxane residue; at least one of the Z2 groups is siloxane residue; X is hydrogen atom or a univalent hydrocarbon group; (p) is 2 or 3; (m) is 1-10; and at least one of Z1 and Z2 is an alkoxy group) in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel organopolysiloxane, a compounding agent for rubber containing the same, a rubber composition and a tire using the same, and more particularly, to an organopolysiloxane containing a sulfide group and an alkoxy group in the molecule. Polysiloxane, a compounding agent for rubber containing the same, and vulcanizability of a vulcanizable silica compounded rubber composition by compounding the rubber compound, particularly modulus, abrasion resistance and t
The present invention relates to a rubber composition and a tire capable of improving physical properties such as an δ balance.

[0002]

2. Description of the Related Art Rubber compositions comprising silica mixed with various unvulcanized rubbers are known. For example, rubber compositions for tire treads having low heat generation and excellent abrasion resistance are known. Has been used as However, although the tire tread containing silica has good grip on wet roads, there is a problem in that before vulcanization, the viscosity of the unvulcanized compound increases and the productivity deteriorates. In particular, when silica and carbon are simply mixed at the same time, sufficient contact and reaction occur between carbon and rubber,
Although sufficient mixing was promoted, the rubber and silica were not sufficient, causing poor dispersion of the silica and failing to make full use of the characteristics of the silica.

There have been various proposals for solving such a problem, but none of them is practically satisfactory. For example, a method has been proposed in which diethylene glycol or a fatty acid is added to a rubber composition, a metal carboxylate is added, or silica is previously treated with silicone oil (see, for example, JP-A-6-248116). However, none of these methods are practically sufficient.

[0004] Further, there is no method other than taking measures such as increasing the number of times of mixing to prevent burning and a reduction in cohesion at the time of mixing. In addition, when carbon and silica are mixed, they are separately mixed. In reality, the mixing time or the number of times of mixing is increased. Again, this issue
A compound obtained by alkoxylating a linear or cyclic polysiloxane containing a SiH group is added (for example, see JP-A-9-19-1).
A method has been proposed, but the use of this compound is not yet satisfactory, and furthermore, it has no reactive group with rubber in the molecule. Another problem is that the polysiloxane component bleeds out.

Accordingly, the present invention can be used as a rubber compounding agent without substantially impairing the properties of the silica-containing vulcanizable rubber composition, for example, properties such as low heat build-up and abrasion resistance. Novel organopolysiloxane which improves the processability of unvulcanized rubber composition and does not cause the compound to bleed out on the surface, compounding agent for rubber containing the same, rubber composition using the same, and rubber An object is to provide a tire using the composition for a tread.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, have reached the present invention.

That is, as described above, the vulcanization properties of a tire tread containing silica are good, but the rubber composition containing silica has a drawback that the processability when unvulcanized is inferior. This is due to the silanol groups present on the silica surface, and the cohesive force of the silanol groups causes the structure to be formed in the rubber composition and the viscosity to increase. It is estimated that it will decrease.

Further, a silane coupling agent is often used in combination with the silica-containing rubber composition to reinforce the rubber. However, the silanol group in the lumen of the silica particles reacts with the silane coupling agent. Therefore, there is a problem that a large amount of the silane coupling agent must be added to the silane coupling agent to reduce the reinforcing effect. As in the prior art, when a polar substance such as diethylene glycol is added thereto, the phenomenon that a polar compounding agent such as a vulcanization accelerator is adsorbed can be prevented to some extent, but cannot be completely prevented, and a silane coupling agent or the like cannot be prevented. Neither was it possible to prevent substances that chemically bond with the silica particles from binding to the lumen.

[0009] In contrast, the present inventors have the following general formula _{^{(1) R 1 -SiZ 1 3}} (1) ( wherein, R ¹ is hydrocarbon of monovalent substituted or unsubstituted C1-18 Represents a hydrogen group, Z ¹ is selected from an OX group or a siloxane residue, and at least one is a siloxane residue.
X represents a hydrogen atom or a monovalent hydrocarbon group. ) And the following general formula (2): Z ² _p (CH ₃ ) _(3-p) Si—R ² —S _m —R ² —Si (CH ₃ ) _(3-p) Z ² _p (2) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, Z ² is selected from an OX group or a siloxane residue, and at least one is a siloxane residue. X is Hydrogen atom or 1
And p represents 2 or 3, and m represents 1 to 10. However, at least one of Z ¹ and Z ² is an alkoxy group. A rubber composition comprising an organopolysiloxane (A) having a sulfide group and an alkoxy group in the molecule having a structural unit represented by the formula (I) in the molecule and having a number average molecular weight of 600 to 300,000. When compounded inside, the alkoxy group reacts with the silanol group and covers the surface of the silica particles, so solving the problems of the prior art,
It is possible to effectively suppress an increase in viscosity caused by the cohesive force and polarity of the silanol group and wasteful consumption of polar additives such as a vulcanization accelerator. The organopolysiloxane (A) of the present invention has a structure in which the alkoxy groups in the molecule are bonded in a network after the reaction with the silica, so that the hydrocarbon groups are well-aligned on the silica surface, and the conventionally known alkoxy group-containing Dispersion improvement effect is higher than organopolysiloxane,
In addition, since the compound has a sulfide group in the molecule, this compound also reacts with rubber, does not bleed out to the rubber surface unlike the conventionally known organopolysiloxane containing alkoxy group, and can further improve the physical properties of rubber. And found that the present invention was achieved.

Accordingly, the present invention is represented by the following general formula _{^{(1) R 1 -SiZ 1 3}} (1) ( wherein, R ¹ represents a monovalent hydrocarbon group substituted or unsubstituted 1 to 18 carbon atoms , Z ¹ are selected from an OX group or a siloxane residue, and at least one is a siloxane residue.
X represents a hydrogen atom or a monovalent hydrocarbon group. ) And the following general formula (2): Z ² _p (CH ₃ ) _(3-p) Si—R ² —S _m —R ² —Si (CH ₃ ) _(3-p) Z ² _p (2) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, Z ² is selected from an OX group or a siloxane residue, and at least one is a siloxane residue. X is Hydrogen atom or 1
And p represents 2 or 3, and m represents 1 to 10. However, at least one of Z ¹ and Z ² is an alkoxy group. A) an organopolysiloxane having a sulfide group and an alkoxy group in the molecule having a structural unit represented by the following formula in the molecule and having a number average molecular weight of 600 to 300,000, and the organopolysiloxane (A). A rubber compounding agent is provided.

In this case, it is composed of the above-mentioned organopolysiloxane (A) and at least one kind of inert powder (B),
A rubber compounding agent having a weight ratio of (A) / (B) = 70/30 to 5/95 can be obtained. In addition, the present invention relates to 100 parts by weight of raw rubber,
0 parts by weight and the compounding amount of the organopolysiloxane (A) containing the above compounding agent for rubber is 0.2 parts by weight based on the total composition.
A rubber composition blended in an amount of up to 30% by weight, and a tire using the rubber composition for a tread.

Hereinafter, the present invention will be described in more detail.
The organopolysiloxane of the present invention is represented by the following general formula _{^{(1) R 1 -SiZ 1 3}} (1) ( wherein, R ¹ represents a monovalent hydrocarbon group substituted or unsubstituted 1 to 18 carbon atoms, Z ¹ is selected from an OX group or a siloxane residue, and at least one is a siloxane residue.
X represents a hydrogen atom or a monovalent hydrocarbon group. ) And the following general formula (2): Z ² _p (CH ₃ ) _(3-p) Si—R ² —S _m —R ² —Si (CH ₃ ) _(3-p) Z ² _p (2) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, Z ² is selected from an OX group or a siloxane residue, and at least one is a siloxane residue. X is Hydrogen atom or 1
And p represents 2 or 3, and m represents 1 to 10. However, at least one of Z ¹ and Z ² is an alkoxy group. ) Having a sulfide group and an alkoxy group in the molecule having a number average molecular weight of 600 to 300,000.

In the above formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and is a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, tert-butyl group, hexyl group, cyclohexyl group, octyl group, alkyl group such as decyl group, vinyl group, allyl group, propenyl group, butenyl group, alkenyl group such as hexenyl group, phenyl group, xylyl group, tolyl group, etc. Aryl group, benzyl group, phenylethyl group,
Unsubstituted monovalent hydrocarbon groups such as aralkyl groups such as phenylpropyl group, and part or all of hydrogen atoms of these monovalent hydrocarbon groups are halogen atoms such as chlorine, bromine and fluorine, (meth) acryl group, Meth) acryloxy group, amino group,
Substituted monovalent carbon such as a group substituted with a functional group such as an alkylamino group, a glycidyl group, a glycidoxy group, a mercapto group, a ureido group, an isocyanate group, or a group in which a hetero atom such as O, NH, NCH ₃ or S is interposed. Hydrogen group, for example, chloropropyl group, (meth) acryloxypropyl group,
Aminopropyl group, aminoethylaminopropyl group, glycidoxypropyl group, mercaptopropyl group, ureidopropyl group, isocyanatepropyl group, and the like. Among these, from the viewpoint of cost and reactivity, methyl, ethyl, propyl Groups are preferred.

Z ¹ is an OX group or a siloxane residue, and X is a hydrogen atom or a monovalent hydrocarbon group. In this case, the monovalent hydrocarbon group has 1 to 8 carbon atoms, especially 1 to 8 carbon atoms.
4 are preferable, and examples thereof include an alkyl group, an alkenyl group, an aryl group, and an aralkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group, a hexyl group, a cyclohexyl group, and a phenyl group. .
The siloxane residue is bonded to an adjacent silicon atom via an oxygen atom, and is represented by -O-Si≡. However, since the oxygen atom is shared with the adjacent silicon atom,
It can be expressed as _1/2 . Examples of Z ¹ include an OH group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a siloxane residue and the like.

In this case, it is necessary that at least one of Z ¹ is a siloxane residue. Also, Z ¹
It is preferable that at least one is an OX group, particularly an alkoxy group. As the alkoxy group, a methoxy group and an ethoxy group, which are advantageous in terms of reactivity and cost, are preferable, and an ethoxy group is more preferable in view of safety of generated alcohol.

R ² has 1 to 10 carbon atoms, especially 3 to 6 carbon atoms.
Represents a divalent hydrocarbon group, such as an alkylene group, an arylene group, a group to which these are bonded, and examples thereof include a methylene group, an ethylene group, a propylene group, an isobutylene group, a hexylene group, and a decylene group. Among them, a propylene group is preferred from the viewpoint of cost.

Z ² is an OX group or a siloxane residue,
It can be exemplified the same ones as exemplified for Z ^1. Also in this case, at least one of Z ² needs to be a siloxane residue. Also, at least one
One is preferably an OX group, particularly an alkoxy group.
At least one of Z ¹ and Z ² needs to be an alkoxy group. Without the alkoxy group, the effect of reinforcing the rubber cannot be sufficiently obtained.

P represents 2 or 3, and p is preferably 3 from the viewpoint of reactivity with silica. m represents 1 to 10, m is preferably 2 to 8 from the viewpoint of reactivity with rubber, and more preferably 2 to 4 for the purpose of preventing burning of the rubber during kneading. These sulfide components are generally a mixture of sulfides, and preferably have an average composition of m = 2 to 4.

The organopolysiloxane (A) of the present invention has at least one alkoxy group for reacting with a silanol group on the silica surface. This group may be on any of the main chain, side chain and terminal. Furthermore, it is important to contain a sulfide group in the molecule, and by having this sulfide group, a reaction with rubber occurs at the time of vulcanization, which is effective in improving physical properties, and this polysiloxane bleeds out of the rubber. To prevent them from getting lost.

The organopolysiloxane (A) of the present invention
Is represented by the following formulas (5) to
_{^{(7) SiZ 1 4 (5}} ) R 1 -Si (CH 3) Z 1 2 (6) R 1 -Si (CH 3) 2 Z 1 (7) ( wherein, R ^1, Z ¹ is as defined above And at least one is a siloxane residue.) May be included.

When the above formula (6) is included as another structural unit, the stability of the compound is reduced. Therefore, the content is preferably 30 mol% or less in terms of Si.
When formula (7) or (8) is included as another structural unit, the content is preferably 30 mol% or less in terms of Si from the viewpoint of reactivity with silica.

The method for producing the alkoxy group-containing organopolysiloxane having a sulfide group in the molecule can be carried out by a conventionally known method. For example, it can be generally produced as follows.

(A) Formula (1a) R ¹ —SiZ ³ ₃ (1a) (wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms, and Z ³ represents OX X represents a hydrogen atom or a monovalent hydrocarbon group.)
In indicated the organosilane or organopolysiloxane with the formula having the structural unit _{(3) (XO) p (} CH 3) (3-p) Si-R 2 -S m -R 2 -Si (CH 3) (3- _p) (OX) _p (3) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, X represents a hydrogen atom or a monovalent hydrocarbon group, and p represents 2
Or 3, m shows 1-10. However, at least one of Z ³ and OX is an alkoxy group. A) reacting with a sulfide group-containing silicon compound in the presence of a catalyst.

(B) Formula (1a) R ¹ —SiZ ³ ₃ (1a) (wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms, and Z ³ represents OX X represents a hydrogen atom or a monovalent hydrocarbon group.)
In organosilane or organopolysiloxane with formula (4) having a structural unit represented _{(XO) p (CH 3)} (3-p) Si-R 2 -Y (4) ( wherein, R ² is C 1 -C X represents a hydrogen atom or a monovalent hydrocarbon group, Y represents a halogen, p represents 2 or 3. However, at least one of Z ³ and OX is an alkoxy group. ) In the presence of a catalyst, and then reacting with an alkali polysulfide compound.

(C) Formula (1b) R ¹ —Si (Z ⁴ ) ₃ (1b) wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms; ⁴ is a halogen group such as a chlorine atom,
OX group or siloxane residue, X represents a hydrogen atom or a monovalent hydrocarbon group. ) Organosilane or organopolysiloxane with the formula having the structural unit represented by _{(3) (XO) p (} CH 3) (3-p) Si-R 2 -S m -R 2 -Si (CH 3) (3 _-p) (OX) _p (3) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, X represents a hydrogen atom or a monovalent hydrocarbon group, and p represents 2
Or 3, m shows 1-10. However, at least one of Z ³ and OX is an alkoxy group. A) a method of co-hydrolyzing the sulfide group-containing silicon compound and the other hydrolyzable group-containing organic silicon compound shown in (1), or pre-hydrolyzing the organic silicon compound, followed by a co-condensation reaction.

(D) Formula (1a) R ¹ —SiZ ³ ₃ (1a) (wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms, and Z ³ represents OX X represents a hydrogen atom or a monovalent hydrocarbon group.)
In organosilane or organopolysiloxane with formula (4) having a structural unit represented _{(XO) p (CH 3)} (3-p) Si-R 2 -Y (4) ( wherein, R ² is C 1 -C X represents a hydrogen atom or a monovalent hydrocarbon group, Y represents a halogen, p represents 2 or 3. However, at least one of Z ³ and OX is an alkoxy group. The co-hydrolysis of the haloalkyl group-containing silicon compound represented by the formula) and other hydrolyzable group-containing organic silicon compounds, or the above-mentioned organic silicon compound is preliminarily hydrolyzed, followed by a co-condensation reaction,
A method of reacting with an alkali polysulfide compound.

Further, it can be produced by reacting an organopolysiloxane containing a SiH group and a sulfide group with an alcohol, followed by a dehydrogenation reaction.
It can also be obtained by performing a dehydrogenation reaction between an H group-containing halogenoalkylpolysiloxane and an alcohol, and then reacting with an alkali polysulfide compound.

Here, in the above method (a), a catalyst for reacting an organosilane or organopolysiloxane having a structural unit represented by the formula (1) with a sulfide group-containing silicon compound represented by the formula (3) Alkali metal compounds such as potassium hydroxide, sodium hydroxide, sodium methylate, sodium ethylate, potassium siliconate, and phosphorus siliconate; and alkali catalysts such as amine compounds such as diazabicycloundecene. And acid catalysts such as hydrochloric acid, sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, trifluoromethanesulfonic acid, paratoluenesulfonic acid, and sulfonic acid type ion exchange resin. Among them, sulfuric acid, trifluoromethanesulfone, Acid catalysts such as acids and sulfonic acid type ion exchange resins are preferred. The amount of the catalyst is arbitrary, but is 0.0001 to 5.0 of the total amount.
% By weight is preferred. Further, the reaction temperature is not particularly limited, but may be performed at about 0 to 150 ° C., and particularly preferably 20 to 150 ° C.
About 80 ° C. is preferable. The reaction time is not particularly limited, but may be about 30 minutes to 20 hours, and particularly preferably about 3 to 15 hours. Use of a solvent in this reaction is optional, and aliphatic hydrocarbons such as hexane, heptane and octane; aromatic hydrocarbons such as benzene, toluene and xylene; alcohols such as methanol and ethanol; methoxyethanol and ethoxyethanol And ethers such as dimethoxyethanol, diethoxyethanol, methoxymethanol acetate, ethoxyethanol acetate, tetrahydrofuran and dioxane; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; and amides such as dimethylformamide. When an acid catalyst is used, it is preferable to deactivate the catalyst by performing a neutralization treatment after completion of the reaction. In this case, potassium hydroxide, sodium hydroxide, sodium hydroxide and the like are used as neutralizing agents. Alkali metal compounds such as methylate, sodium ethylate, potassium siliconate and phosphorus siliconate, amine compounds such as diazabicycloundecene, and alkali compounds such as sodium hydrogen carbonate and magnesium oxide can be used.

The reaction ratio between the compound containing the structural unit represented by the formula (1) and the sulfide group-containing silicon compound represented by the formula (3) is arbitrary, but the structural unit represented by the formula (1) is not limited. And the weight ratio of the compound containing the sulfide group / silicon compound represented by the formula (3) may be 5 to 95/95 to 5, more preferably 30 to 80/80 to 30.

Examples of the compound represented by the formula (1) include methyltriethoxysilane hydrolytic condensation oligomer, methyltrimethoxysilane hydrolytic condensation oligomer, methyltriethoxysilane and dimethyldiethoxysilane cohydrolytic condensation. Oligomers, methyltrimethoxysilane and dimethyldimethoxysilane cohydrolytic condensation oligomer, trimethylmethoxysilane, methyltrimethoxysilane and dimethyldimethoxysilane cohydrolysis condensation oligomer, and the like.

Examples of the compound represented by the formula (3) include:
Bis- [3- (triethoxysilyl) -propyl] tetrasulfide, bis- [3- (triethoxysilyl)-
Propyl] disulfide, bis- [3- (triethoxysilyl) -propyl] trisulfide, and a mixed composition thereof.

In the above method (c), the formula (1)
b) co-hydrolysis of an organosilane or an organopolysiloxane having a structural unit represented by the formula (3) with a sulfide group-containing silicon compound represented by the formula (3) and another hydrolyzable group-containing organic silicon compound; After hydrolysis of the compound in advance, as a catalyst for co-condensation reaction,
Tin compounds such as dibutyltin dilaurate, titanium compounds such as tetrabutyl titanate, acids such as acetic acid, oxalic acid, hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid and trifluoromethanesulfonic acid, sodium hydroxide, potassium hydroxide, diaza Examples thereof include an alkali catalyst such as bicycloundecene and a solid catalyst such as an ion exchange resin. The amount of the catalyst is arbitrary, but is preferably about 0.0001 to 5.0% by weight of the total amount.

Examples of other hydrolyzable group-containing organosilicon compounds include dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, propylmethyldimethoxysilane, propylmethyldiethoxysilane, haloalkylmethyl Dimethoxysilane and the like, and hydrolysates thereof,
The condensate etc. are illustrated. Considering the stability of the system and the reactivity with silica, the amount of these other hydrolyzable group-containing organosilicon compounds is also 50 mol% of the whole.
The following is preferred. Use of a solvent in the hydrolysis reaction is optional, and aliphatic hydrocarbons such as hexane, heptane and octane; aromatic hydrocarbons such as benzene, toluene and xylene; alcohols such as methanol and ethanol; methoxyethanol; Ethoxyethanol, dimethoxyethanol, diethoxyethanol, methoxymethanol acetate, ethoxyethanol acetate, ethers such as tetrahydrofuran and dioxane, acetone, ketones such as methyl ethyl ketone, esters such as ethyl acetate,
Amides such as dimethylformamide are exemplified. At this time, the amount of water to be added may be at least 1 mol of water per molecule, and may be added by diluting with a solvent at that time, and the solvent may be alcohol such as methanol or ethanol. And ethers such as methoxyethanol and tetrahydrofuran.

The organopolysiloxane (A) having a sulfide group and an alkoxy group in the molecule of the present invention is useful as a compounding agent for rubber, and the compounding agent for rubber of the present invention uses this organopolysiloxane (A). Including. By compounding the compounding agent for rubber of the present invention into the vulcanizable rubber composition, the abrasion resistance can be further improved as compared with the related art. In this case, the compounding agent for rubber of the present invention is particularly effective for the vulcanizable rubber composition containing silica.

The above-mentioned organopolysiloxane (A) may be used alone in the rubber composition as a compounding agent for rubber, but comprises the organopolysiloxane (A) and at least one kind of inert powder (B). A compounding agent for rubber can also be compounded. Here, the inert powder means a powder having low reactivity with the organopolysiloxane (A) having a branched structure of the present invention. In this case, the inert powder (B) and the organopolysiloxane (A) may be a mixture of the inert powder and the organopolysiloxane, a mixture of the inert powder impregnated with the organopolysiloxane, and a mixture of the inert powder. Any surface treated with an organopolysiloxane may be used, but preferably, an inert powder impregnated with an organopolysiloxane.

Examples of the inert powder (B) include carbon black, talc, calcium carbonate, stearic acid, silica, aluminum hydroxide, clay and the like. The amount of the inert powder (B) is (A) /
The weight ratio of (B) is from 70/30 to 5/95, more preferably from 60/40 to 30/70. If the amount of the inert powder is too small, silica and silica mixed in the rubber composition are used. If the organopolysiloxane (A) reacts too quickly, the reinforcing property may be reduced, and if it is too large, the surface treatment effect of the organopolysiloxane (A) on the silica may be weakened.

When the compounding agent for rubber of the present invention is compounded in a vulcanizable rubber composition, the polysiloxane (A) having a sulfide group and an alkoxy group in the molecule is preferably 0.2 to 0.2 parts by mass of the rubber composition. It is recommended that the content be 30% by weight, especially 1.0 to 20% by weight. If the compounding amount of the polysiloxane (A) having a sulfide group and an alkoxy group in the molecule is too small, the desired effect may not be obtained.

Here, the rubber component blended as a main component in the vulcanizable rubber composition according to the present invention is any rubber conventionally blended generally in various rubber compositions, for example, natural rubber (NR) Diene rubbers such as polyisoprene rubber (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), acrylonitrile-butadiene copolymer rubber (NBR), and butyl rubber (IIR); Propylene copolymer rubber (F
PR, EPDM) and the like can be used alone or as an arbitrary blend.

In the vulcanizable rubber composition of the present invention, the polysiloxane (A) having a sulfide group and an alkoxy group of the present invention can substitute for a silane coupling agent. The addition of the coupling agent is optional, and any silane coupling agent conventionally used in combination with the silica filler may be added. Typical examples thereof are vinyltrimethoxysilane, vinyltriethoxysilane, γ- Glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, β-
Aminoethyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-
Mercaptopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, bis- [3- (triethoxysilyl) -propyl] tetrasulfide, bis- [3- (triethoxysilyl) -propyl] disulfide, bis- [3 -(Triethoxysilyl) -propyl] trisulfide and the like. Among these, bis- [3- (triethoxysilyl) -propyl] tetrasulfide, bis- [3- (triethoxysilyl) -propyl] disulfide, bis- [3- (triethoxysilyl) -propyl] trisulfide Sulfides and the like and mixtures thereof are most preferred from the viewpoint of further improving processability.

In the rubber composition according to the present invention, 5 to 100 parts by weight, particularly 5 to 80 parts by weight, of silica for compounding rubber is preferably mixed with 100 parts by weight of the raw rubber (rubber component). (I.e., a polysiloxane having a sulfide group and an alkoxy group in the molecule (A) or a premix thereof with an inert powder (B)) in the molecule of the entire composition. Is blended so that the blending amount of the polysiloxane (A) having the following formula is 0.2 to 30% by weight, particularly preferably 1 to 10% by weight. In addition, you may use these rubber compounding agents in mixture of 2 or more types.

In the rubber composition according to the present invention, in addition to the above essential components, carbon black, a vulcanizing or crosslinking agent,
Vulcanization or crosslinking accelerators, various oils, anti-aging agents, fillers, for tires such as plasticizers, it is possible to compound various additives that are generally compounded for general rubber, such a compound, The composition can be kneaded and vulcanized by a general method and used for vulcanization or crosslinking. The compounding amounts of these additives can also be conventional general compounding amounts as long as they do not contradict the object of the present invention.

Although the rubber composition of the present invention is effectively used for various uses, it is particularly preferable to use it for a tire tread.

[0043]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The following commercially available products were used as the other ingredients used in the following examples and comparative examples. Natural rubber: RSS # 1 SBR: Nipol NS116 (Nippon Zeon) BR: NP1220 (Nippon Zeon) Silica: Nipsil AQ (Nippon Silica) Silane coupling agent: KBE-846 (Shin-Etsu Chemical Co., Ltd.) bis- [3 -(Triethoxysilyl) -propyl]
Tetrasulfide carbon black: Seast KH (manufactured by Tokai Carbon) Powder sulfur: 5% oil-treated powder sulfur Antioxidant 6C: N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine Vulcanization acceleration Agent CZ: N-cyclohexyl-2-benzothiazylsulfenamide Zinc oxide: Zinc flower No. 3 Stearic acid: Industrial stearic acid

[Synthesis Example 1] An alkoxy group-containing organopolysiloxane having a sulfide group in the molecule (1) A methyltrimethyl compound having an average molecular weight of 1,000 was placed in a 1-liter separable flask equipped with a stirrer, a cooler, and a thermometer. 100 g of ethoxysilane hydrolysis-condensation oligomer, bis- [3
-(Triethoxysilyl) -propyl] tetrasulfide (100 g) was charged, and at 50 to 60 ° C, 0.3 g of trifluoromethanesulfonic acid was slowly added with stirring. Thereafter, stirring was continued at 60 ° C. for 8 hours. Then 20%
0.7 g of sodium ethylate was added to neutralize and deactivate the catalyst. Thereafter, volatile components were removed at 80 ° C. and 20 mmHg. When the obtained product was purified by filtration, the obtained compound was 180 g. Its average molecular weight measured by GPC was 1,8 in terms of polystyrene.
00.

GPC chart before reaction and GPC after reaction
The chart is shown in FIG. 1 and FIG. In this GPC analysis, since the analysis was carried out with a RI solvent using a THF solvent, no methyltriethoxysilane hydrolyzed condensation oligomer was detected, and bis- [3- (triethoxysilyl)-
[Propyl] tetrasulfide alone. On the other hand, after the reaction, the amount of bis- [3- (triethoxysilyl) -propyl] tetrasulfide component decreased, and it was found that a polymer component having a sulfide group introduced on the polymer side was detected. It can be confirmed that it is incorporated in the chain.

[Synthesis Example 2] An alkoxy group-containing organopolysiloxane having a sulfide group in the molecule (2) In Synthesis Example 1, bis- [3- (triethoxysilyl) -propyl] tetrasulfide was replaced with bis-
[3- (Triethoxysilyl) -propyl] trisulfide was used in the same manner except that 100 g was used.
A compound having a molecular weight of 1,700 was obtained.

Synthesis Example 3 Organopolysiloxane containing an alkoxy group having a sulfide group in the molecule (3) In Synthesis Example 1, methyltrimethoxysilane having a molecular weight of 1,500 was used instead of the methyltriethoxysilane hydrolysis-condensation oligomer. And dimethyldimethoxysilane co-hydrolyzed condensation oligomer.
A compound having a PC molecular weight of 2,500 was obtained.

[Synthesis Example 4] An alkoxy group-containing organopolysiloxane having a sulfide group in the molecule (4) In Synthesis Example 1, methyltriethoxysilane having a molecular weight of 15,000 was used instead of the methyltriethoxysilane hydrolytic condensation oligomer. The same operation was carried out except that the hydrolysis-condensation oligomer was used. Since this product had a high viscosity and could not be purified by filtration, the product concentrated under reduced pressure was directly subjected to GPC analysis. As a result, a compound having a GPC molecular weight of 18,000 was obtained.

[Synthesis Example 5] For comparison, a compound having the following structure was synthesized by reacting methyl hydrogen polysiloxane with ethanol.

[0051]

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Examples 1 to 6, Comparative Examples 1 and 2 The components shown in Table 1 were kneaded with a closed mixer, and a vulcanization accelerator and sulfur were kneaded with an open roll to obtain a rubber composition. .
The obtained rubber composition was press-vulcanized in a mold of 15 × 15 × 0.2 cm at 160 ° C. for 20 minutes to prepare a target test piece (rubber sheet), and the vulcanization properties were evaluated. The method for testing the vulcanizability of the composition obtained in each example is as follows. Table 1 shows the results.

[0053] unvulcanized physical properties Mooney viscosity was measured at 100 ° C. Based on JIS K6300. Vulcanization rate: 9 at 160 ° C based on JIS K6300
The time to reach 5% vulcanization was measured. Scorch time: The time required for the viscosity to increase by 5 points at 125 ° C. was measured based on JIS K6300. Vulcanized physical carbon / silica dispersion state: The vulcanized rubber was cut with a sharp blade, and the surface was visually observed and evaluated. ○: Almost no poorly dispersed lumps of carbon and silica
Evenly distributed. C: Some poorly dispersed masses of carbon and silica are scattered, but others are dispersed to some extent. C: Powder-like things can be seen from the cut surface, and countless defective lumps of carbon and silica are found. 300% deformation stress, breaking strength, breaking elongation: JIS K6
251 (dumbbell-shaped No. 3 type). tan δ: Measured with a viscoelastic device rheograph solid manufactured by Toyo Seiki Seisakusho at 20 Hz, initial elongation 10%, dynamic strain 2% (sample width 5 mm, temperature 0 ° C. and 60 ° C.). Abrasion resistance: Measured with a Lambourn-type testing machine, and the loss on abrasion was indicated by an index. Abrasion resistance (index) = [(weight loss in reference test piece) / (weight loss in each test piece)] × 100 Oil component bleed-out: The surface of the vulcanized rubber was visually observed and evaluated. …: No oil bleed. ×: Bleeding of oil is observed.

[0054]

[Table 1]

[0055]

According to the present invention, when the organopolysiloxane having a sulfide group and an alkoxy group is compounded in a silica compounded rubber composition as a compounding agent for rubber, the compound can be prepared without compounding a silane coupling agent as a compounding component. Alternatively, even when compounded, the dispersibility of silica is improved, and the physical properties (tensile, wear resistance, tan δ) of the rubber composition are improved,
It is suitable for rubber compositions for tire treads, and further, compared to conventionally known alkoxy group-containing organopolysiloxanes, there is no oil bleed out,
It is suitable for a rubber composition for a tire tread.

[Brief description of the drawings]

FIG. 1 is a GPC chart before a reaction in Synthesis Example 1.

FIG. 2 is a GPC chart after the reaction of Synthesis Example 1.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08L 83/06 C08L 83/06 83/14 83/14 (72) Inventor Akira Yamamoto Matsuida-machi, Usui-gun, Gunma Prefecture No. 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory F-term (reference) 4J002 AC011 AC031 AC061 AC081 BB151 BB181 CP102 DA036 DE146 DE236 DJ016 DJ036 DJ046 EF056 GN01 4J035 BA04 BA14 CA01K CA01N CA051 CA061 CA26K CA26LA04

Claims (7)

[Claims] 1. A following general formula _{^{(1) R 1 -SiZ 1 3}} (1) ( wherein, R ¹ represents a monovalent hydrocarbon group substituted or unsubstituted 1 to 18 carbon atoms, Z ¹ is It is selected from an OX group or a siloxane residue, at least one of which is a siloxane residue.
X represents a hydrogen atom or a monovalent hydrocarbon group. ) And the following general formula (2): Z ² _p (CH ₃ ) _(3-p) Si—R ² —S _m —R ² —Si (CH ₃ ) _(3-p) Z ² _p (2) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, Z ² is selected from an OX group or a siloxane residue, and at least one is a siloxane residue. X is Hydrogen atom or 1
And p represents 2 or 3, and m represents 1 to 10. However, at least one of Z ¹ and Z ² is an alkoxy group. An organopolysiloxane having a structural unit represented by the formula (1) in the molecule and having a sulfide group and an alkoxy group in the molecule having a number average molecular weight of 600 to 300,000. 2. The following general formula (1a): R ¹ —SiZ ³ ₃ (1a) (wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms, and Z ³ represents An OX group or a siloxane residue, and X represents a hydrogen atom or a monovalent hydrocarbon group.)
Organosilane or organopolysiloxane with the following formula having a structural unit represented in _{(3) (XO) p (} CH 3) (3-p) Si-R 2 -S m -R 2 -Si (CH 3) ( _3-p) (OX) _p (3) (wherein, R ² represents a divalent hydrocarbon group having 1 to 10 carbon atoms, X represents a hydrogen atom or a monovalent hydrocarbon group, and p represents 2
Or 3, m shows 1-10. However, at least one of Z ³ and OX groups is an alkoxy group. The organopolysiloxane according to claim 1, which is obtained by reacting a sulfide group-containing silicon compound represented by the formula) in the presence of a catalyst. 3. The organopolysiloxane according to claim 2, wherein sulfuric acid, trifluoromethanesulfonic acid or a sulfonic acid group-containing ion exchange resin is used as the catalyst. 4. A compounding agent for rubber comprising the organopolysiloxane (A) according to claim 1. 5. An organopolysiloxane (A) according to any one of claims 1 to 3 and at least one inert powder (B), wherein the weight ratio is (A) / (B) =
A compounding agent for rubber having a ratio of 70/30 to 5/95. 6. Silica 5 based on 100 parts by weight of raw rubber
The rubber compounding agent according to claim 4 or 5 and the compounding amount of the organopolysiloxane (A) contained therein in an amount of 0.2 to 30% by weight based on the total composition. A rubber composition that is compounded. 7. A tire using the rubber composition according to claim 6 for a tread.