JP2002220492A - Production method of rubber composition for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire excellent in wettability resistance and abrasion resistance. SOLUTION: The production method of the rubber composition for the tire comprises the following three steps. In the first mixing step, a copolymer component, a filler component composed of silica and a carbon black, a silane coupling agent composed of an alkoxysilane compound having a sulfur bond, and a specific polysiloxane compound are mechanically mixed at 145-160 deg.C for 30 sec.-5 min., and in the second mixing step, a zinc white, stearic acid, wax, an antioxidant and the like are mixed with a mixture obtained by the first step, at 145-160 deg.C for 30 sec.-5 min., and in the second mixing step, a zinc white, stearic acid, wax, an antioxidant and the like are mixed with a mixture obtained by the first step, at 145-160 deg.C for 30 sec.-5 min., and further in the third mixing step, sulfur and a specific vulcanizing promoter are mixed with the mixture obtained by the second step, at a temperature below vulcanizing temperature to form the rubber composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rubber composition for a tire, and more particularly, to a method in which rubber, silica, carbon black and a coupling agent are mixed in a first step and then zinc is added in a second step. A rubber composition for tires is manufactured in a three-step process in which Hua, stearic acid and other additives other than the vulcanization system are mixed, and a vulcanization system containing tetrabenzylthiuram disulfide (TBzTD) is further mixed in the third step. About the method. When the rubber composition obtained by such a method is used as a tire cap tread compound, a tire excellent in performance such as wet resistance and abrasion resistance can be manufactured.

[0002]

2. Description of the Related Art It has been attempted to reduce the fuel consumption of a cap tread compound by mixing silica and a silane coupling agent into a rubber composition. In this case, however, the reaction between silica and the silane coupling agent is carried out. There is a problem in that the temperature is reduced to a temperature at which the sulfur bond in the silane coupling agent is not broken. Several proposals have been made to solve this problem.

[0003] For example, JP-A-11-269305 discloses that a rubber polymer is mixed with silica, carbon black, a rubber softener and a silane coupling agent. It describes that a rubber composition having excellent wet resistance and abrasion resistance can be obtained by mixing at a temperature of ° C. However, in this method, it takes time to mix the components, and the reaction of the silane coupling agent is insufficient, so that further improvement is required.

[0004] Japanese Patent Application Laid-Open No. 8-59898 discloses that 95 to 1
A rubber composition containing tetrabenzylthiuram disulfide or zinc dibenzyldithiocarbamate for low-temperature vulcanization at 40 ° C. and a method for vulcanizing the same are described.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to increase the vulcanization rate and the reaction rate of a silane coupling agent, to increase the grip force (wet resistance) on wet roads, and to improve the abrasion resistance. An object of the present invention is to provide a method for producing an excellent rubber composition for a tire.

[0006]

According to the present invention, (1)
(a) (i) Natural rubber (NR), polyisoprene rubber (I)
R), polybutadiene rubber (BR) and glass transition temperature
Conjugated diene and aromatic vinyl having a degree (Tg) of less than -40 ° C
Selected from the group consisting of copolymer rubbers with compounds
15-70 parts by weight of a rubber and (ii) glass transition temperature
Degree (Tg) is -40 ° C or more, and the styrene content is 20 to
60% by weight, conjugate with vinyl content of 13-75% by weight
Copolymer rubber of diene and aromatic vinyl compound
100 parts by weight of a rubber component consisting of 5 parts by weight, (b) (i)
Nitrogen adsorption specific surface area (N_Two SA) is 100-300m^Two /
g of silica and 10 to 110 parts by weight, and (ii) nitrogen adsorption ratio table
Area (N_Two SA) is 50-200m ^Two / G of carbon fiber
A filler composition comprising 10 parts by weight to 110 parts by weight of a rack
40 to 120 parts by weight, (c) 2 to the silica weight
Alkoxysilane compounds containing 15% by weight of sulfur bonds
Silane coupling agent consisting of (d) silica weight
1 to 10% by weight of the formula I:

Embedded image (Wherein R ¹ independently represents a methyl group, an ethyl group or a phenyl group, R ² independently represents a hydrogen or an organic group, m is 0 or an odd number of 1 or more, and n is an integer of 1 or more. ) Having a number average molecular weight of from 200 to 100,0
The polysiloxane of Example 1 was mechanically mixed at a temperature of 145 ° C to 160 ° C for 30 seconds to 5 minutes, and then (2) zinc oxide, stearic acid, wax, aging An additive other than the sulfur and the vulcanization accelerator to be mixed in the following step (3) is added to the mixture.
Mix at a temperature of 60 ° C. for 30 seconds to 5 minutes, and further (3) add the mixture obtained in step (2) to (i) sulfur, (i
i) N-cyclohexyl-2-benzothiazolesulfenamide and / or Nt-butyl-2-benzothiazolesulfenamide and (iii) tetrabenzylthiuram disulfide are mixed at a temperature lower than the vulcanization temperature. A method for producing a rubber composition for a tire is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted research to achieve the above object. As a result, the compounding system of silica / carbon black and a coupling agent is slow in vulcanization of silica. Promotes the reaction with the coupling agent TBzTD and further reacts the coupling agent at a high temperature, and simultaneously mixes zinc white and stearic acid to suppress the reaction between these additives and the coupling agent, thereby reducing the original coupling agent. Was successful in promoting the reaction.

The rubber component (a) used in the rubber composition for a tire according to the present invention includes (i) general natural rubber (NR) and polyisoprene rubber (IR) conventionally used in a rubber composition for a tire. ), Various polybutadiene rubbers (BR)
And a glass transition temperature Tg of less than −40 ° C., preferably a conjugated diene (eg, butadiene or isoprene) and an aromatic vinyl compound (eg, styrene, methylstyrene)
15 to 70 parts by weight, preferably 30 to 50 parts by weight, and (ii) a Tg of -40 ° C or higher, preferably -35 to -20 ° C, and a styrene content of 20 to 60.
Weight, preferably 35-45% by weight and a vinyl content of 13
Of a conjugated diene and an aromatic vinyl compound in an amount of 30 to 85 parts by weight, preferably 40 to 70 parts by weight, and the total amount is 100 parts by weight. It is. The rubber component (a) (i)
Tg of conjugated diene-aromatic vinyl compound copolymer rubber
Is higher than −40 ° C., the rubber becomes too hard and the wet performance is low, which is not preferable. In addition, the Tg of the conjugated diene-aromatic vinyl compound copolymer rubber of the rubber component (a) (ii) is −
If the temperature is lower than 40 ° C., the gripping force is low, which is not preferable. In the present invention, in addition to the two-component copolymer rubbers (i) and (ii), other rubbers (for example, NR, B
R, SBR).

The filler component to be added to the rubber composition for a tire according to the present invention is 40 to 40 parts by weight based on 100 parts by weight of rubber.
120 parts by weight, preferably 50 to 95 parts by weight.
In the present invention, silica 10 to 10 as a filler component
0 parts by weight, preferably 20 to 65 parts by weight, and 10 to 110 parts by weight, preferably 25 to 95 parts by weight of carbon black are blended. If the amount of the filler component is too small, the wear is poor, which is not preferable. On the contrary, if the amount is too large, the wet grip is too low, which is not preferable.

The silica used in the present invention is N ₂ SA
(Measured according to JIS K 6221) 100 to 30
0 m ² / g, can be preferably used any of silica to be blended in the rubber composition for tires conventionally if 120~200m ² / g. This N ₂ SA is 100 m ² /
If it is less than g, the reinforcing effect is small and thus it is not preferable.
If it exceeds 00 m ² / g, the surface activity is too high and processing is difficult, which is not preferable.

The carbon black used in the present invention is N ₂ SA (measured according to JIS K 6221).
0 to 200 m ² / g, preferably 80 to 160 m ² / g
If so, carbon black generally used conventionally in rubber compositions for tires can be used. If the N ₂ SA is less than 50 m ² / g, the reinforcing effect is small, which is not preferable. If it exceeds 200 m ² / g, the surface activity is too high, which is not preferable.

Examples of the silane coupling agent comprising an alkoxysilane compound containing a sulfur bond used in the present invention include the following. That is,
Bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3- Mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-
Mercaptoethyltriethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane,
3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-
Dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide , 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, and the like.From the viewpoint of achieving both the effect of adding a coupling agent and the cost, Bis (3-triethoxysilylpropyl) tetrasulfide and the like are preferred.

The coupling agent comprising an alkoxysilane compound containing a sulfur bond used in the present invention is 2 to 15% by weight, preferably 4 to 12% by weight based on the weight of silica.
use. If the amount is too small, the effect of the coupling agent is small, which is not preferable. On the contrary, if it is too large, the coupling effect is small, although the cost is increased, which is not preferable.

The polysiloxane having a number average molecular weight of 200 to 100,000, preferably 500 to 75,000 represented by the formula (I) used in the present invention is 2 to 15% by weight, preferably 4 to 5% by weight based on the weight of silica. Used at ~ 12% by weight. If the amount is too small, the effect of the polysiloxane is small, which is not preferable. On the contrary, if it is too large, the plasticizing effect is increased, which is not preferable.

The polysiloxane of the formula (I) used in the present invention is synthesized by reacting an Si—H group-containing polysiloxane with an alcohol or a carboxylic acid in the presence of a catalyst.

The following can be exemplified as the above-mentioned ≡Si-H group-containing polysiloxane.

[0017]

Embedded image

The alcohol includes 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 an 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 with an organic compound having a double bond using the above catalyst. Examples of the compound having a double bond include styrene, α-methylstyrene, limonene, and vinylcyclohexene.

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

[0021]

Embedded image

As still 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.

[0023]

Embedded image

Examples of the alkoxysilane include those having the following structural formulas.

[0025]

Embedded image

Examples of the alkoxysilane include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-amino Ethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3
-Glycidoxypropylmethyldimethoxysilane, 2-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3
-Aminopropyltrimethoxysilane and bis- [3-
Silane coupling agents such as (triethoxysilyl) -propyl] tetrasulfide.

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

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 amount is too small, the desired effect cannot be obtained, while if it is too large, the substance which does not bind to silica may exude from the vulcanized product, which is not preferable.

According to the process for producing a rubber composition for a tire according to the present invention, first, in the first step, the above-mentioned components are used in an amount of 145 to 16
30 seconds at a temperature of 0 ° C. (preferably 140 to 155 ° C.)
Mix mechanically for 5 minutes (preferably 1 to 3 minutes), for example using a closed mixer. If the mixing temperature and time are insufficient, the reaction of the silane coupling agent becomes insufficient, which is not preferable. If the mixing temperature and time are excessive, the coupling agent is decomposed and reacts with the rubber.

It is not always necessary to add and mix the above-mentioned carbon black to the whole amount in the first mixing step, and even if a part (for example, 20 to 80% by weight of the whole amount) is added and mixed in the next second mixing step. Good.

According to the present invention, additives other than the vulcanization system such as zinc white, stearic acid, wax, antioxidant and oil are added to the mixture obtained in the first mixing step.
0 ° C., preferably at a temperature of 145 to 155 ° C. for 30 seconds to 5
Mix mechanically for minutes, preferably 2-3 minutes. If the mixing conditions are excessively relaxed, the dispersion of carbon, zinc white, etc. becomes poor, which is not preferable. Conversely, if the mixing conditions are too severe, rubber is burned due to heat generation.

According to the present invention, the mixture obtained in the second mixing step is mixed with the vulcanization system at a temperature lower than the vulcanization temperature, preferably at 90 to 110 ° C., depending on the vulcanization system used. As the vulcanization system, in addition to sulfur generally used, (a) N
-Cyclohexyl-2-benzothiazole and / or N
-T-butyl-2-benzothiazolesulfenamide and (b) tetrabenzylthiuram disulfide (TBz
TD) can be mixed to produce a desired rubber composition for a tire. The compounding amount of the vulcanization accelerator can be a general amount conventionally used widely, for example, N-
Cyclohexyl-2-benzothiazole and / or Nt
-Butyl-2-benzothiazolesulfenamide is preferably used in an amount of 0.5 to 2.5% by weight based on the weight of the polymer, and the amount of TBzTD used is 0.5 to 3.5% based on the weight of the polymer. Parts by weight. If the amount is too small, the effect of accelerating the reaction is small, which is not preferable. On the contrary, if it is too large, the effect of accelerating is large, and the rubber is burnt.

As described above, according to the present invention, zinc white and stearic acid suppress the reaction between silica and the silane coupling agent to weaken the effect of the coupling agent. The use of the agent TBzTD significantly accelerates the silica-based vulcanization reaction.

[0035]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples.

Preparation of Samples of Comparative Examples 1 to 5 and Examples 1 to 5 In the formulations shown in Table I, each component in the first-stage mixing step was mixed and discharged in a 1.8-liter closed mixer under the conditions shown in Table I. As a result, a first-stage mixture was obtained. The components of the second-stage mixing step in Table I were blended with this first-stage mixture and mixed in the second-stage mixture under the conditions shown in Table I. The rubber composition was obtained by mixing. The obtained rubber composition was placed in a 15 × 15 × 0.2 cm mold at 160 ° C. for 2 hours.
Test specimen (rubber sheet) after press vulcanization for 0 minutes
Was prepared, and the following physical properties were evaluated. The results are shown in Table I.

The test methods for evaluating the physical properties of the compositions obtained in the respective examples are as follows. Physical property evaluation test method 1) Vulcanization time T90 (min): Measured at 160 ° C according to JIS K6301. The smaller the value, the shorter the vulcanization time. 2) 300% modulus M300 (MPa): JIS K
3) Breaking strength (MPa): Measured according to JIS K 6251 4) Breaking elongation (%): Measured according to JIS K 6251 5) Tan δ (0 ° C. and 60 ° C.): Toyo The measurement was performed using a viscoelastic spectrometer of Seiki under the measurement conditions of initial strain 10% and dynamic strain 2%. 6) Lambourn abrasion (index): Measured at a temperature of 20 ° C. using a Lambourn abrasion tester. The volume loss of each formulation was calculated, and the loss amount of Comparative Example 1 was set to 100. The larger the number, the smaller the loss and the better the abrasion.

[0038]

[Table 1]

[0039]

[Table 2]

Footnotes in Table I * 1: SBR NIPOL 9529 manufactured by Zeon Corporation
(Tg = -21 ° C) * 2: SBR NIPOL 1712 manufactured by Zeon Corporation
(Tg = −50 ° C.) * 3: Bayer SBR VSL 5025 (Tg =
-19 ° C) * 4: Asahi Kasei SBR Toughden 4350 (Tg =-
* 5: SBR Toughden 1524 manufactured by Asahi Kasei (Tg =-
74 ° C) * 6: Natural rubber (SIR-20) * 7: Polybutadiene rubber, Hicis B, manufactured by Zeon Corporation
R * 8: Rhodia silica (Z1165MP) (N ₂
SA = 165 m ² / g) * 9: Tokai Carbon carbon black (Seast 9)
M) (N ₂ SA = 152 m ² / g) * 10: Aromatic oil manufactured by Showa Shell Sekiyu * 11: Silane coupling agent Si69 manufactured by Degussa * 12: KI-90E manufactured by Nippon Unicar

* 13: First-stage mixture * 14: Carbon black (SEAST 9M) manufactured by Tokai Carbon (N ₂ SA = 152 m ² / g) * 15: Zinc oxide manufactured by Shodo Chemical * 16: Industrial stearin manufactured by NOF Corporation Acid * 17: Antiaging agent S-13 manufactured by Sumitomo Chemical * 18: Wax manufactured by Nippon Seiro * 19: Second stage mixture

* 20: Vulcanization accelerator CBS manufactured by Flexis * 21: Vulcanization accelerator TBzTD manufactured by Flexis * 22: Sulfur manufactured by Tsurumi Chemical

As is clear from the results in Table I, when the blending system of Example 1 was compared with the other blending systems, Comparative Examples 1 to 5, remarkable improvements in workability and wear resistance were observed. Also, as shown in Examples 2 to 5, it was confirmed that even if the polymer was changed, there was an effect, and even if carbon was introduced first, the wear resistance was excellent, and it was recognized that there was no problem in workability. Was done.

[0044]

As described above, according to the present invention, by performing the three-stage mixing, the grip force on the wet surface is increased (improved wet resistance), and the abrasion resistance is improved. And increase in viscosity can be suppressed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/00 C08K 5/00 7/22 7/22 C08L 9/06 C08L 9/06 // (C08L 21 / 00 (C08L 21/00 83:04) 83:04) (C08L 9/06 (C08L 9/06 83:04) 83:04) B29K 7:00 B29K 7:00 9:00 9:00 9:06 9:06 105: 16 105: 16 F term (reference) 4F070 AA05 AA06 AA08 AC04 AC05 AC23 AC50 AC52 AC92 AE01 AE03 AE08 FA01 FB06 FB07 4F201 AA46 AH20 AP05 AP10 AR06 AR11 BA01 BC01 BC03 BC12 BC15 BK74 4J002 AC01W AC03W AC03W CP033 DA037 DA049 DE108 DJ016 EF058 EV169 EV329 EX000 FA096 FA097 FD038 FD149 GN01

Claims (1)

[Claims] 1. (1) (a) (i) natural rubber (NR), poly
Isoprene rubber (IR), polybutadiene rubber (BR)
And a conjugated diene having a glass transition temperature (Tg) of less than -40 ° C.
Group consisting of copolymer rubbers of ene and aromatic vinyl compound
15 to 70 parts by weight of at least one kind of rubber selected from
(Ii) a glass transition temperature (Tg) of -40 ° C. or higher,
When the len content is 20 to 60% by weight and the vinyl content is 13
To 75% by weight of a conjugated diene and an aromatic vinyl compound.
Rubber component 100 comprising 30 to 85 parts by weight of polymer rubber
(B) (i) Nitrogen adsorption specific surface area (N_Two SA) is 100-3
00m^Two / G silica at 10 to 110 parts by weight,
Element adsorption specific surface area (N_Two SA) is 70-200m ^Two / G
Consists of 10 parts by weight to 110 parts by weight of carbon black
40 to 120 parts by weight of filler component, (c) 2 to 15% by weight of sulfur bond based on the weight of silica
Coupling composed of alkoxysilane compounds containing
(D) 1 to 10% by weight based on the weight of silica of the formula I:(Where R¹ Is independently methyl, ethyl or phenyl
A group represented by R^Two Independently represents hydrogen or an organic group;^Three Is
Independently represents an alkyl group or an acyl group, and m is 0 or 1 or more.
Is an integer above, and n is an integer of 1 or more)
Having a number average molecular weight of 200 to 100,000
Polysiloxane at a temperature of 145 ° C to 160 ° C for 30 seconds
Mix mechanically for 5 minutes, and then (2) add zinc white and stearate to the mixture obtained in step (1).
Acid, wax, antioxidant and mixed in the following step (3)
Combining other additives other than sulfur and vulcanization accelerator
Mix at a temperature of 145 to 160 ° C for 30 seconds to 5 minutes.
Then, (3) the mixture obtained in step (2) is added with (i) sulfur, (i
i) N-cyclohexyl-2-benzothiazole sulf
Enamide and / or Nt-butyl-2-benzothia
Solsulfenamide and (iii) tetrabenzylthio
Mix uram disulfide at a temperature below the vulcanization temperature.
And a method for producing a rubber composition for a tire.