JP2853986B2 - Rubber compounding agent and rubber composition using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compounding agent for rubber and a rubber composition using the same. More specifically, the present invention relates to a vulcanizable composition by specifying a compounding order of a polysiloxane and a silane coupling agent or powder. The present invention relates to a rubber compounding agent and a rubber composition which improve the vulcanization properties of a silica-containing rubber composition, particularly the properties such as modulus, abrasion resistance and balance of tan δ. Here, “silica” means wet silica,
Dry process silica, which has a nitrogen specific surface area of 50 to 400 m ² / g used for rubber, and “vulcanization” means vulcanization by peroxide in addition to ordinary vulcanization with sulfur. And the like.

[0002]

2. Description of the Related Art Rubber compositions comprising silica mixed with various rubbers are known, and are used, for example, as rubber compositions for tire treads having low heat generation and excellent wear resistance.
However, although the tire tread containing silica has low rolling resistance and good grip on wet roads, phenomena such as viscosity increase of unvulcanized compound, vulcanization delay, reduction of cohesion in the tire manufacturing process occur, There was a problem that productivity deteriorated. There have been various proposals for solving such a problem.

[0003]

From such a viewpoint, we have previously proposed a rubber composition containing a polysiloxane (filed on August 31, 1995, Japanese Patent Application No. Hei 7-22307).
9). The present inventors have studied to further improve the vulcanization properties of the rubber composition having such a composition.

[0004] Accordingly, the present invention provides a vulcanizable rubber composition containing silica, in particular, modulus, abrasion resistance and ta.
It is an object of the present invention to provide a rubber compound improving properties such as nδ balance and a silica-containing vulcanizable rubber composition using the same.

[0005]

According to the present invention, (A)
A polysiloxane having the following alkoxysilyl group (I) having a number average molecular weight of 200 to 300,000 and a silane coupling agent (B) were prepared by mixing (A) / (B) = 95/5 to 5 /
There is provided a rubber compounding agent comprising 95 parts. ≡Si-OR ¹ (I) (wherein, R ¹ is a substituted or unsubstituted 1 having 1 to 18 carbon atoms)
It is a monovalent hydrocarbon group or an organic group containing an ether bond. )

According to the present invention, the polysiloxane (A) is added to (C) at least one kind of powder by (A) /
(C) There is provided a rubber compounding agent impregnated at a ratio of 70/30 to 5/95.

[0007] According to the present invention, based on 100 parts by weight of the raw rubber, 5 to 100 parts by weight of silica and the compounding amount of the rubber compounding agent according to claim 1 are mixed with the total amount of the polysiloxane. 3. The rubber according to claim 2, wherein 5 to 100 parts by weight of silica, a silane coupling agent and 100 parts by weight of a rubber composition or raw rubber compounded in an amount of 0.2 to 30% by weight per product. The present invention provides a rubber composition comprising a compounding agent for use in an amount such that the compounding amount of the polysiloxane contained therein is 0.2 to 30% by weight based on the total composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the structure, operation and effect of the present invention will be described in detail. As described above, the tire tread containing silica has good vulcanization properties, but has a drawback that the workability in the unvulcanized state is poor. According to the findings of the present inventors, this is due to silanol groups (≡Si—OH) present on the silica surface, and a structure is formed in the rubber composition due to the cohesive force of the silanol groups to increase the viscosity. Or
An unvulcanized composition due to the phenomenon that vulcanization accelerators are adsorbed due to the polarity of the silanol group and vulcanization is delayed, or the cohesion of the mixture is reduced due to insufficient compatibility with the non-polar rubber. The workability of the steel is reduced. Further, a silane coupling agent is often used in combination with the silica-containing rubber composition to reinforce the rubber.However, a silanol group also exists in the inner cavity of the silica particles, and this is considered as a silane coupling agent. There is a problem that a large amount of the silane coupling agent must be blended because the reaction causes loss of the silane coupling agent and a reduction in 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.

On the other hand, when the polysiloxane (A) having the alkoxysilyl group of the formula (I) is blended into the rubber composition, the alkoxysilyl group (I) reacts with the silanol group to cover the surface of the silica particles. Therefore, it is necessary to solve all the problems of the prior art and effectively suppress the increase in viscosity caused by the cohesive force and polarity of silanol groups and the wasteful consumption of polar additives such as vulcanization accelerators and silane coupling agents. Can be. However, the silane coupling agent that enhances the reinforcing properties of silica and the polysiloxane that improves the processability of silica are both competitive reactions in which they react with silanol groups on the silica surface. I found out. That is, if the silica and the polysiloxane react first, the reinforcing property decreases, which is not preferable. Therefore, in the present invention, by preliminarily mixing the coupling agent and the polysiloxane and mixing them with the rubber,
Preventing only the polysiloxane from reacting first,
Alternatively, the reaction to silica can be delayed by impregnating a non-reactive filler (inert powder) such as carbon black or a powder such as silica with the polysiloxane in advance. A decrease in sulphate properties can be prevented.

The polysiloxane (A) containing an alkoxysilyl group (I) blended in the rubber composition according to the present invention has an alkoxysilyl group (I) that reacts with a silanol group, A size that covers the surface of the particles and exhibits a lubricating effect, that is, a number average molecular weight of 200 to 3
It must be a polymer (or oligomer) of 00,000, preferably 500-50,000. Therefore, in the polysiloxane (A) used in the present invention, the presence of the ≡Si—O—R ¹ group is essential, and this group may be present in any of the main chain, the side chain, and the terminal. Further, there may be a hydrogen group or another organic group. Such a polysiloxane is a known substance and can be generally produced, for example, as follows.

The polysiloxane (A) containing an alkoxysilyl group is synthesized by reacting a polysiloxane containing a Si--H group with an alcohol in the presence of a catalyst.

The following can be exemplified as the above-mentioned シ ロ キ サ ン Si-H group-containing polysiloxane.

[0013]

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As the alcohol, methanol, ethanol, propanol, butanol, pentanol,
In addition to heptanol, octanol, octadecanol, phenol, benzyl alcohol, alcohols having an oxygen atom such as ethylene glycol monomethyl ether and diethylene glycol monomethyl ether can be exemplified. Examples of the carboxylic acid include acetic acid, propionic acid, palmitic acid, stearic acid, and myristic acid.

Further, as the catalyst, chloroplatinic acid, platinum-ether complex, platinum-olefin complex, PdCl
₂ (PPh ₃ ) ₂ , RhCl ₂ (PPh ₃ ) ₂ tin octylate, zinc octylate, or acid or base catalyst can be used. It is synthesized by reacting the corresponding ≡Si—H group-containing polysiloxane with an alcohol or a carboxylic acid in the presence of a catalyst. As a method for introducing an organic group, ≡Si
It is easily introduced by reacting -H and an organic compound having a double bond using the above catalyst. As the compound having a double bond, styrene, α-methylstyrene,
Limonene, vinylcyclohexene and the like.

Another method is to synthesize the corresponding ≡Si—H group-containing polysiloxane with a double bond-containing alkoxysilane as shown below in the presence of the above-mentioned catalyst. it can.

[0017]

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As yet another method, the polysiloxane (A) used in the present invention can be synthesized by reacting a silanol-terminated polysiloxane with an alkoxysilane in the presence of a catalyst such as a divalent tin compound. it can. Examples of such a silanol-terminated polysiloxane include the following.

[0019]

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Examples of the alkoxysilane include the following alkoxysilanes, and further include silane coupling agents shown in Table I.

[0021]

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[0022]

[Table 1]

The polysiloxane (A) used in the present invention can be synthesized by reacting a polysiloxane having a reactive functional group on the side chain or terminal with the silane coupling agent shown in Table I above. Examples of the polysiloxane having a reactive functional group include an epoxy group, an amino group,
Those having a mercapto group, a carboxyl group or the like can be exemplified.

As described above, the end groups and side chains of the polysiloxane (A) used in the present invention are not particularly limited, and are determined by the type of raw materials used in the production.

The polysiloxane (A) used in the present invention is blended in an amount of 0.2 to 30% by weight, particularly preferably 1.0 to 10% by weight, based on the rubber composition. If the blending amount of the polysiloxane (A) is too small, the desired effect cannot be obtained. On the contrary, if the blending amount is too large, the substance which does not bind to silica may exude from the vulcanized product, which is not preferable.

The rubber compounded as a main component in the vulcanizable rubber composition according to the present invention may be any rubber conventionally compounded in various rubber compositions, for example, natural rubber (N
R), polyisoprene rubber (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), acrylonitrile-butadiene copolymer rubber (NBR), diene rubbers such as butyl rubber (IIR), and the like. Ethylene-propylene copolymer rubber (EPR, E
PDM) or the like can be used alone or as an arbitrary blend.

The silane coupling agent (B) used in the vulcanizable rubber composition of the present invention can be any silane coupling agent conventionally used in combination with a silica filler. The ones shown in Table I can be mentioned. Of these, bis- [3- (triethoxysilyl) -propyl] tetrasulfide is most preferred from the viewpoint of processability.

When the silane coupling agent (B) is blended with the vulcanizable rubber composition according to the present invention, the amount of the silane coupling agent (B) used can be reduced as compared with the prior art, and the abrasion resistance can be reduced. Can be further improved. The preferred amount of the silane coupling agent (B) used in the present invention is such that the ratio (weight ratio) of the polysiloxane (A) to the silane coupling agent (B) in the composition is 95/5 to 5/95, more preferably. 60/40 to 80/20. If the amount of the silane coupling agent (B) is too small, the desired effect cannot be obtained, and if it is too large, burning (scorch) in the mixing or extrusion step is liable to occur.

In the rubber composition of the second embodiment according to the present invention, at least one kind of powder (C) conventionally conventionally compounded in a rubber composition is mixed with the polysiloxane (A). Examples of the powder (C) include inert powders such as carbon black, talc, calcium carbonate, and stearic acid, and silica. Here, the inert powder refers to a powder having low reactivity with the polysiloxane (A) of the present invention. The amount of the inert powder (C) is (A) / (C)
70/30 to 5/95 by weight, more preferably 60/30
If the amount of the inert powder is too small in the ratio of / 40 to 30/70, the silica and the polysiloxane react too quickly, and the reinforcing property is reduced. Is not preferred because the surface treatment effect of the above is weakened. The method for impregnating the powder (C) with the polysiloxane (A) is not particularly limited, but any of mixers, kneaders, mills and the like which are usually used depending on the intended use can be used.

The silica compounded rubber composition according to the present invention is used in an amount of 5 to 1% for silica compounding rubber with respect to 100 parts by weight of the raw rubber.
00 parts by weight, preferably 5 to 80 parts by weight, and the above-mentioned compounding agent for rubber (that is, a pre-mixture of polysiloxane (A) and silane coupling agent (B) or powder (C)) in the total composition. The siloxane (A) is blended so that the blending amount is 0.2 to 30% by weight, preferably 1 to 10% by weight.
Further, two or more of these rubber compounding agents may be used in combination.

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, tires such as plasticizers, can be blended with various additives that are generally blended for other general rubber,
Such a composition can be kneaded and vulcanized in a conventional manner into a composition, which can be 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.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to standard examples, examples and comparative examples, but it goes without saying that the technical scope of the present invention is not limited to these examples.

The following commercially available products were used as the other components in the following standard examples, examples and comparative examples. Natural rubber: RSS # 1 SBR: Nipol NS116 (manufactured by Nippon Zeon) NP9528 (33.3% oil exhibition manufactured by Nippon Zeon) NP1730 (33.3% oil exhibition manufactured by Nippon Zeon) BR: NP1220 (manufactured by Nippon Zeon) Silica: Nipsil AQ (Nippon Silica) Silane coupling agent: Si69 (Dexa) (chemical name:
Bis- [3- (triethoxysilyl) -propyl] tetrasulfide) Polysiloxane: Polymethylethoxysiloxane Carbon Black 1: Seast KH (Tokai Carbon) Carbon Black 2: Seast 9M (Tokai Carbon)

Preparation of Polymethylethoxysiloxane
Polymethyl hydro diene siloxane 10 to granulation ethanol 75g and 1% chloroplatinic acid isopropyl solution 100μl
0 g (KF99, Shin-Etsu Chemical Co., Ltd.) was added dropwise at 70 ° C. for 1 hour, and after completion of the addition, the mixture was reacted at 80 ° C. for 8 hours to produce a polymethylethoxysiloxane having the following structural formula. Reaction rate 90
%.

[0035]

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Powdered sulfur: 5% oil-treated powdered sulfur Antioxidant 6C: N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine Vulcanization accelerator CZ: N-cyclohexyl-2- Benzothiazyl sulfenamide Vulcanization accelerator DPG: diphenylguanidine Zinc oxide: Zinc flower No. 3 Stearic acid: Industrial stearic acid

Preparation of Samples Among the components shown in Tables II, III and IV, the components to be blended in the first step were first mixed in a 1.8 liter closed mixer.
Kneading for ~ 5 minutes, mixing the ingredients of the second step into the masterbatch released when the temperature reaches 165 ± 5 ° C, kneading the vulcanization accelerator and sulfur with an 8-inch open roll, and preparing a rubber composition I got The obtained rubber composition is 15 × 15 ×
The target test piece (rubber sheet) was prepared by press vulcanization at 160 ° C. for 20 minutes in a 0.2 cm mold, and the vulcanization properties were evaluated.

The method for testing the vulcanizability of the composition obtained in each example is as follows. Vulcanization properties 1) 300% deformation stress, breaking strength, breaking elongation: JIS
Measured in accordance with K6251 (dumbbell-shaped No. 3 type) 2) tan δ (0 ° C. and 60 °): 20 Hz, visco-elastic device rheograph solid manufactured by Toyo Seiki Seisaku-sho, initial elongation 1
Measured at 0% dynamic strain 2% (sample width 5 mm, temperature 0/60 ° C.) 3) Abrasion resistance: Measured with a Lambourn-type tester, and the wear loss is indicated as an index. Abrasion resistance (index) = [(Standard Example 9 Weight loss / (sample weight loss)] × 100

Examples 1-2 and 4 (standard examples) and Examples 3 and
5 (Examples) These examples show the evaluation results of a polysiloxane / silane coupling agent mixture and a polysiloxane / carbon mixture in an NR / SBR system. The composition and evaluation results are as shown in Table II.

[0040]

[Table 2]

Examples 6-7 and 9 (standard) and Examples 8 and
10 (Examples) These examples show the polysiloxane / silane coupling agent mixture and polysiloxane /
3 shows the evaluation results of a carbon mixture. The formulations and results are as shown in Table II.

[0042]

[Table 3]

Examples 11 to 12 and 14, 16 (standard examples)
Examples 13, 15 and 17 (Examples) These examples show the evaluation of polysiloxane / silane coupling agent mixtures, polysiloxane / carbon mixtures and polysiloxane / silica mixtures in SBR systems.

[0044]

[Table 4]

[0045]

As described above, according to the present invention, Examples 1-2 and 4, Examples 6-7 and 9, and Examples 11-12 and 14 are used.
As shown in Examples 3, 5, 8, 9 and 13 and 15, a polysiloxane containing an alkoxysilyl group (I) was mixed with a silane coupling agent or an inert filler. By doing so, mixing can be performed without excessively reacting with the silanol groups on the silica surface by 1-step mixing, and each physical property (tensile, abrasion resistance, tan δ) is improved. However, the excellent tan δ balance in the present invention is indicated by a large tan δ gradient between 0 ° C. and 60 ° C.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/09 C08K 5/09 5/54 5/54 C08L 83/06 C08L 83/06 // (C08L 21/00 83:06 (56) References JP-A-6-248116 (JP, A) JP-A-62-48743 (JP, A) JP-A-57-172925 (JP, A) JP-A 9-111044 (JP, A) JP-A-8-302070 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 7/00-21 / 02,23 / 16,83 / 00-83/16 C08K 3 / 04,3 / 34,3 / 36,5 / 09,5 / 54

Claims (7)

(57) [Claims] (A) The following alkoxysilyl group (I) is
A polysiloxane having a number average molecular weight of 200 to 300,000 and a silane coupling agent (B)
(B) A compounding agent for rubber, comprising a ratio of from 95/5 to 5/95. ≡Si-OR ¹ (I) (R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms or an organic group containing an ether bond . ) 2. Polysiloxane (A) according to claim 1.
To (C) at least one inert powder (A) / (C)
= Compounding agent for rubber impregnated at a ratio of 70/30 to 5/95. 3. A powder comprising silica, carbon black, and tar.
Calcium, calcium carbonate, and stearic acid.
3. The rubber according to claim 2, which is at least one kind of inert powder.
For compounding agents. 4. The powder according to claim 2, wherein the powder is silica.
Combination agent for rubber. 5. Silica 5 based on 100 parts by weight of raw rubber
A rubber composition comprising the rubber compounding agent according to claim 1 in an amount of 0.2 to 30% by weight based on the total amount of the polysiloxane contained therein. Stuff. 6. Silica 5 based on 100 parts by weight of raw rubber
3 to 100 parts by weight, a silane coupling agent and
The compounding agent for rubber listed above is
The compounding amount is 0.2 to 30% by weight based on the total composition.
A rubber composition formulated in an amount. 7. The rubber composition according to claim 5 or 6,
Tire used for red.