JP2002220491A - Production method of rubber composition for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a rubber composition, excellent in wetness resistance and abrasion resistance, and having no over curing after vulcanizing. SOLUTION: The production method of the rubber composition comprises the following steps (1)-(3). (1) A rubber component which is composed of a diene-based rubber having Tg of -40 deg.C or below and a diene-based copolymer rubber having a specific stylene-content and vinyl-content, a filler component which is composed of silica having a specific N2 SA and a carbon black having the specific N2 SA, a silane coupling agent which is composed of a specific alcoxysilane compound, and a polysiloxane having a specific number-average molecular weight, are mechanically mixed, and (2) sulfur and other additives excepting a vulcanizing promoter are blended with a mixture obtained by the step (1), to be heated and mixed, and further, (3) sulfur, N-cyclohexyl-2- benzothiazolsulpheneamide and/or N-t-butyl-2-benzothiazolsulpheneamide and tetrabenzylthiuram sulfide are mixed with the mixture obtained by the step (2) 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. The present invention relates to a method for producing a rubber composition for tires in a three-step process of mixing a flower, stearic acid and other additives except for a vulcanization system, and further mixing a vulcanization system containing tetrabenzylthiuram disulfide in a third step. The rubber composition obtained by such a method produces a tire excellent in performance such as wet resistance and abrasion resistance when used as a tire cap tread rubber without causing vulcanization burn during compounding. be able to.

[0002]

2. Description of the Related Art It has been practiced to incorporate silica and a silane coupling agent into a rubber composition to lower rolling resistance and improve wet performance, but in this case, vulcanization burn occurs during mixing. There was a problem of doing. 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.

Japanese Patent Application Laid-Open No. Hei 10-182847 discloses a sulfur-curable rubber composition using a silica coupling agent in the form of an organosilane disulfide / trisulfide. This composition is effective in preventing vulcanization and burning during vulcanization, but has the problem of slow vulcanization. Further, Japanese Unexamined Patent Publication No. Hei 9-111044 discloses a rubber composition for a vulcanizable tire tread containing silica, which has a problem that it is sensitive to temperature and may cause burning during vulcanization.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to increase the vulcanization rate and the reaction rate of a silane coupling agent without causing vulcanization burn, and to provide a grip force (wet resistance) on a wet road. ) And to provide a method for producing a rubber composition for tires having excellent wear resistance.

[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 having an (Tg) of -40 ° C or lower and aromatic vinylation
At least selected from the group consisting of copolymer rubbers with compounds
15-70 parts by weight of rubber and (ii) glass transition temperature
(Tg) is more than −40 ° C., and the styrene content is 20 to 60.
Conjugated die having a vinyl content of 13 to 75% by weight
Copolymer rubber of ethylene and aromatic vinyl compound
(B) (i) nitrogen
Adsorption specific surface area (N_Two SA) is 100-300m^Two / G
10 to 110 parts by weight of silica, and (ii) specific surface area for nitrogen adsorption
(N_Two SA) is 70-200m ^Two / G of carbon black
Filler component 4 consisting of 10 parts by weight to 110 parts by weight
0 to 120 parts by weight, (c) 2 to 15 parts by weight based on the weight of silica
Formula in weight%: (RO)_Three Si (CH_Two )_Three -Sx- (CH_Two )_Three Si
(OC_Two H_Five )_Three (In the formula, x is 2 at 75% or more, and the average x is 2 to 2.4.
A) an alkoxysilane compound containing a sulfur bond
(D) 2 to 15% by weight based on the weight of silica 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
00 polysiloxane, and then mechanically mixing
(2) An additive other than sulfur and a vulcanization accelerator to be mixed in the following step (3) is added to the mixture obtained in the step (1), and the mixture is mixed at a temperature of 150 to 180 ° C. for 30 seconds to 5 seconds. For 3 minutes and then (3) the mixture obtained in step (2) is added to (i) sulfur, (ii) N-cyclohexyl-2-benzothiazolesulfenamide and / or Nt-butyl-
A method for producing a rubber composition for a tire, comprising mixing 2-benzothiazolesulfenamide and (iii) tetrabenzylthiuram disulfide at a temperature not higher than the vulcanization temperature 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. Promoted with the agent tetrabenzylthiuram disulfide, and further reacting the coupling agent at a higher temperature, while simultaneously mixing zinc white and stearic acid separately,
The reaction between these additives and the coupling agent was suppressed, and the reaction of the original coupling agent was successfully promoted. According to the present invention, furthermore, the reaction between silica and the coupling agent is promoted, and the heat generation during mixing is suppressed in order to suppress the vulcanization burn, so that the vulcanization burn during compounding can be prevented.

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 −40 ° C. or lower, preferably −
15 to 70 selected from a conjugated diene (for example, butadiene rubber or natural rubber) and an aromatic vinyl compound (for example, styrene and butadiene) copolymer at 40 to -120 ° C.
Parts by weight, preferably 20 to 50 parts by weight, and (ii) Tg is-
More than 40 ° C, preferably -35 to 0 ° C, styrene content of 2
A copolymer rubber of a conjugated diene and an aromatic vinyl compound having a vinyl content of 0 to 60% by weight, preferably 35 to 45% by weight and a vinyl content of 13 to 75% by weight, preferably 13 to 50% by weight.
-85 parts by weight, preferably 50-80 parts by weight, the total amount of which is 100 parts by weight. When the Tg of the conjugated diene-aromatic vinyl compound copolymer rubber of the rubber components (a) and (i) is higher than −40 ° C., the temperature dependence of physical properties increases and the material becomes sensitive to changes in the use environment. And the Tg of the conjugated diene-aromatic vinyl compound copolymer rubber of the rubber components (a) and (ii) is less than -40 ° C,
It is not preferable because the grip force is reduced. In the present invention, the two-component copolymer rubbers (i) and (i)
In addition to i), other rubbers (for example, NR, BR, SBR) can be included.

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 90 parts by weight.
In the present invention, silica 10 to 10 as a filler component
0 parts by weight, preferably 15 to 60 parts by weight, and 10 to 110 parts by weight, preferably 20 to 90 parts by weight of carbon black are blended. If the amount of the filler component is too small, the gripping force is reduced, 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).
0~200m ² / g, preferably 120~200m ² /
As long as it is g, carbon black conventionally used in rubber compositions for tires can be used. If the N ₂ SA is less than 70 m ² / g, the reinforcing effect is small, which is not preferable. On the other hand, if it exceeds 200 m ² / g, the surface activity is too high and processing is difficult, which is not preferable.

In the silane coupling agent of the above formula comprising an alkoxysilane compound containing a sulfur bond used in the present invention, at least 75% of x in the formula is 2 and the average value is 2 to 2.
It is important that the number be 4, preferably 4 to 12. If the average value exceeds 2.4, the number of -S-S-S bonds increases, so that the dissociation of S tends to occur, which is not preferable because it causes vulcanization burn. A typical example of such a silane coupling agent is, for example, Si75 (Degres).
commercially available as sa).

The silane coupling agent used in the present invention is used in an amount of 2 to 15% by weight, preferably 4 to 12% by weight based on the weight of silica. If the amount is too small, the reinforcing effect of silica is small and the physical properties deteriorate, which is not preferable. On the contrary, if it is too large, it causes vulcanization and burning, 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 reinforcing effect of the silica is small and the physical properties are deteriorated, 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 method for producing a rubber composition for a tire according to the present invention, the above-mentioned components are firstly added in the first step, preferably at a temperature of 150 to 180 ° C. (more preferably 155 to 16 ° C.).
(0 ° C.) for preferably 30 seconds to 5 minutes (more preferably 1.5 to 2.5 minutes) mechanically, for example using a closed mixer. If the mixing temperature and the mixing time are insufficient, the reaction between the silica and the silane coupling agent is not sufficiently completed, which is not preferable.

The above carbon black need not always be added and mixed in the first mixing step, but a part thereof (for example, 10 to 100% by weight of the total amount) may be added and mixed in the next second mixing step. .

According to the present invention, a vulcanizing agent and a vulcanization accelerator added to the mixture obtained in the first mixing step in the following third mixing step, such as zinc oxide, stearic acid, a wax, and an antioxidant. Additives other than the vulcanizing system, such as 15
0 to 180 ° C, preferably 135 to 145 ° C at 3
Mix mechanically for 0 seconds to 5 minutes, preferably 1.5 to 2.5 minutes. If the mixing conditions are excessively relaxed, the dispersion of the filler becomes poor, which is not preferable.

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 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 3% by weight based on the weight of the rubber containing no vulcanizing agent, and the amount of tetrabenzylthiuram disulfide used is preferably 0% based on the weight of the rubber containing no vulcanizing agent. 0.5 to 3 parts by weight. If the amount is too small, the vulcanization rate will be low, which is not preferable.

As described above, according to the present invention, the reaction between the coupling agent and zinc oxide or stearic acid is suppressed to promote the reaction of the coupling agent with silica, and the use of the vulcanization accelerator TBzTD. This significantly promotes 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 Comparative Examples 1-4 and Examples 1-5 In the formulations shown in Table I, each component of 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 15 × 15 × 0.2
A target test piece (rubber sheet) was prepared by press vulcanization at 160 ° C. for 20 minutes in a mold having a diameter of 1 cm, 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 Using the viscoelastic spectrometer of Seiki, initial strain 10%, dynamic strain 2%
Was measured under the following measurement conditions. 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 wear resistance.

[0039]

[Table 1]

[0040]

[Table 2]

Footnotes in Table I * 1: SBR NIPOL 9529 manufactured by Zeon Corporation of Japan
(Tg = -21 ° C) * 2: SBR NIPOL 1712 manufactured by Zeon Corporation
(Tg = -50 ° C) * 3: SBR VSL 5025 manufactured by BAYER (Tg
* -19: SBR T.A. manufactured by Asahi Kasei. 4350 (Tg = -24
° C) * 5: SBR T. made by Asahi Kasei. 1524 (Tg = −74
° C) * 6: Natural rubber (TSR) * 7: Nippon Zeon polybutadiene rubber Hicis B
R * 8: Rhodia silica (Z1165MP) (N
₂ SA = 165 m ² / g) * 9: Carbon black made by Tokai Carbon (Seast 9
M) (N ₂ SA = 150 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 (Seam 9M) manufactured by Tokai Carbon (N ₂ SA = 150 m ² / g) * 15: Zinc oxide manufactured by Seido Chemical * 16: Industrial stearin manufactured by NOF Corporation Acid * 17: Flexis anti-aging agent S-13 * 18: Nippon Seiro wax Orisoace * 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, Example 1
When the blending system of Comparative Example 1 was compared with Comparative Examples 1 to 4 which are other blending systems, a remarkable improvement in abrasion was observed at a specific mixing temperature, and as shown in Examples 2 to 5, the polymer was changed. However, high wear resistance and high 0 ° C. tan δ
It was confirmed that the wet resistance was improved.

[0045]

As described above, according to the present invention, by performing three-stage mixing, vulcanization burn and viscosity during mixing can be suppressed.
The grip force on the wet surface is increased (improved wet resistance), and the wear resistance can be improved.

──────────────────────────────────────────────────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 AC53 AC92 AE01 AE03 AE08 FA01 FB06 FB07 4F201 AA46 AH20 AP05 AP10 AR06 AR11 BA01 BC01 BC03 BC12 BC15 BD08 BK74 4J002 AC01W AC03 BC05X CP033 DA037 DA049 DJ016 EV169 EV329 EX088 FA096 FA097 FD149 GN01

Claims (2)

[Claims] 1. (1) (a) (i) natural rubber (NR), poly
Isoprene rubber (IR), polybutadiene rubber (BR)
And a conjugated die having a glass transition temperature (Tg) of -40 ° C or lower.
The group consisting of copolymer rubbers of ethylene and aromatic vinyl compounds?
15 to 70 parts by weight of at least one rubber selected from
(Ii) The glass transition temperature (Tg) exceeds −40 ° C.
Content is 20 to 60% by weight, and vinyl content is 13 to
75% by weight of conjugated diene and aromatic vinyl compound
100-weight rubber component consisting of 30 to 85 parts by weight of united 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 a filler component, (c) 2 to 15% by weight based on the weight of silica: Formula (RO)_Three Si (CH_Two )_Three -Sx- (CH_Two )_Three Si
(OC_Two H_Five )_Three (In the formula, x is 2 at 75% or more, and the average x is 2 to 2.4.
A) an alkoxysilane compound containing a sulfur bond
(D) 2 to 15% 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
(2) mechanically mixing the polysiloxane with the mixture obtained in step (1);
Contains other additives other than sulfur and vulcanization accelerator mixed in
And mix at a temperature of 150 to 180 ° C for 30 seconds to 5 minutes
And (3) adding (i) sulfur, (i) to the mixture obtained in step (2).
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. 2. The method according to claim 1, wherein the mechanical mixing in the step (1) is carried out at 145 to 145.
The method according to claim 1, which is performed at a temperature of 160C for 30 seconds to 5 minutes.