JP4076631B2 - Rubber composition - Google Patents

Description

【００５３】
表１より、特定の条件で２段階の混練を行なうことにより、ムーニー粘度がさがり、加工性がよくなるばかりか、耐摩耗性、ウェットスキッド性、転がり抵抗がよくなるということがわかる。
【００５４】
【発明の効果】
本発明によれば、シリカとシランカップリング剤との反応効率を高めることにより、低転がり抵抗性（低燃費性）およびウェット性能に優れたタイヤトレッド用ゴム組成物をうることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber composition for a tire tread.
[0002]
[Prior art]
Conventionally, carbon black has been used as a reinforcing material in rubber compositions for tires, but recently, silica has been added particularly according to market demands for wet performance, wear resistance and fuel efficiency. It has become. In this case, polyethylene glycol and a large amount of a silane coupling agent are blended in order to improve the dispersibility of silica and not to deteriorate the processability.
[0003]
However, the silane coupling agent needs to react with silica during processing of the rubber composition to be chemically bonded, and it is necessary to strictly control conditions such as temperature and the number of kneading times, resulting in poor productivity. There is.
[0004]
In order to efficiently react the silanol groups on the silica surface with the silane coupling agent, the amount of the silane coupling agent is considered to be several weight% of silica. When using a kneader, the reaction efficiency is inferior, so the amount of the silane coupling agent needs to be 5 to 15% by weight (preferably 8% by weight) of silica, and it remains unreacted in the rubber composition. There was a problem that the remaining silane coupling agent caused rubber burning during processing and deterioration of the destructive properties of the vulcanized rubber.
[0005]
Furthermore, when sulfur is contained in the silane coupling agent, if the kneading temperature is too high, a crosslinking reaction proceeds in the rubber composition, resulting in poor processability and poor physical properties of the rubber composition after vulcanization.
[0006]
[Problems to be solved by the invention]
In view of the above facts, the object of the present invention is to react a silica and a silane coupling agent by kneading the rubber composition comprising silica, a silane coupling agent and an n-alkylamine under specific conditions. The object is to obtain a rubber composition having improved efficiency and excellent processability and physical properties.
[0007]
[Means for Solving the Problems]
In the present invention, (a) a diene rubber, silica, a silane coupling agent, and an n-alkylamine having 3 to 18 carbon atoms are kneaded at a temperature of 120 ° C. or less to obtain a kneaded product, and then (b) After adding other additives except the vulcanizing agent, vulcanization auxiliary and vulcanization accelerator to the kneaded product, kneading while heating from the temperature in the step (a) to a temperature of 160 ° C. or higher. The present invention relates to a rubber composition to be obtained.
[0009]
The present invention further includes (a) a step of kneading a diene rubber, silica, a silane coupling agent, and an n-alkylamine having 3 to 18 carbon atoms at a temperature of 120 ° C. or lower to obtain a kneaded product, and ( b) A method for producing a rubber composition including a step of kneading at a temperature of 160 ° C. or higher after adding other additives excluding a vulcanizing agent, a vulcanizing aid and a vulcanization accelerator to the kneaded product. Related.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an improvement of a rubber composition comprising silica, a silane coupling agent and an n-alkylamine described in Japanese Patent Application No. 10-187295.
[0012]
The present invention has the greatest feature in that two-stage kneading is performed when obtaining a rubber composition. By performing this two-stage kneading, the reaction efficiency between silica and the silane coupling agent can be increased, and a rubber composition excellent in wet grip, low fuel consumption, and wear resistance can be obtained.
[0013]
First, in step (a), which is the first step, a diene rubber, silica, a silane coupling agent, and n-alkylamine are kneaded at a temperature of 120 ° C. or lower to obtain a kneaded product.
[0014]
The diene rubber used in the present invention is not particularly limited as long as it is conventionally used in the tire field. For example, natural rubber (NR), styrene butadiene rubber (SBR), isoprene rubber (IR), Examples include ethylene propylene diene rubber (EPDM), isoprene butadiene rubber (IBR), butadiene rubber (BR), and butyl rubber (IIR), and these may be used alone or in any combination as long as the effects of the present invention are not impaired. Can be used. Of these, NR, SBR, IR, and BR are preferably used from the viewpoint of rubber strength.
[0015]
Next, the silica used in the present invention is not particularly limited as long as it is conventionally used in the field of tires, but has a nitrogen adsorption specific surface area of 100 from the viewpoint of compatibility between reinforcement and silica dispersibility. ~300m preferably has a ² / g, further, from the viewpoint of the reinforcing property as a tire tread, as the nitrogen adsorption specific surface area of 100 to 250 m ² / g is particularly preferred.
[0016]
Examples of commercially available silicas include Nipsil VN3, Nipsil AQ manufactured by Nippon Silica Kogyo Co., Ltd., and Ultrasil VN3 manufactured by Degussa Japan.
[0017]
The blending amount of silica in the present invention may be 10 to 150 parts by weight with respect to 100 parts by weight of the diene rubber, but is preferably 20 to 90 parts by weight from the viewpoint of tire wear and grip. .
[0018]
Next, carbon rubber may be blended in the rubber composition of the present invention, and such carbon black is not particularly limited as long as it is conventionally used in the field of tires, but it is dispersible. To a nitrogen adsorption specific surface area of 30 to 200 m ² / g, and a compressed dibutyl phthalate (24M4DBP) oil absorption of 30 to 150 ml / 100 g is preferable. Further, in terms of reinforcement, the nitrogen adsorption specific surface area is Particularly preferred is 50 to 200 m ² / g and a 24M4DBP oil absorption of 50 to 150 ml / 100 g.
[0019]
The blending amount of carbon black in the present invention may be 0 to 150 parts by weight with respect to 100 parts by weight of the diene rubber, but is 20 to 90 parts by weight from the viewpoint of tire wear and grip. preferable.
[0020]
Next, the silane coupling agent compounded in the rubber composition of the present invention is not particularly limited as long as it is conventionally used in the field of tires. For example, bis (3-triethoxysilylpropyl) tetra Sulfide, bis (2-triethoxylylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyl Triethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyl Limethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilyl Propyl-N, N-dimethylcarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc. are mentioned, and these may be used alone or in any combination. It can be used in conjunction. Of these, bis (3-triethoxysilylpropyl) tetrasulfide is preferably used from the viewpoint of the coupling effect and cost.
[0021]
Here, about the compounding quantity of a silane coupling agent, it should just be 2-20 weight% of the compounding quantity of a silica from the point of a coupling effect, and it is 2-15 weight% from the point of workability. Further, it is particularly preferably 2 to 10% by weight from the viewpoint of preventing the deterioration of the fracture characteristics of the rubber composition after vulcanization.
[0022]
Next, in this invention, in order to improve the reaction efficiency of a silica and a silane coupling agent, n-alkylamine is mix | blended.
[0023]
The n-alkylamine used in the present invention may have 3 to 18 carbon atoms from the viewpoint that the catalytic effect is sufficiently exhibited, but is preferably 3 to 12, and more preferably 3 to 6. Is preferred.
[0024]
Specifically, n-propylamine (3 carbon atoms), n-butylamine (4 carbon atoms), n-pentylamine (5 carbon atoms), n-hexylamine (6 carbon atoms), n-heptylamine (carbon) 7), n-octylamine (carbon number 8), n-nonylamine (carbon number 9), n-decylamine (carbon number 10), n-undecylamine (carbon number 11), n-dodecyloctylamine (carbon) (Equation 12), n-tetradecylamine (carbon number 14), n-cetylamine (carbon number 16), n-octadecylamine (carbon number 18), and the like. These may be used alone or in any combination. it can. Especially, it is preferable to use n-butylamine, n-hexylamine, etc. (C3-C6) from the point that a catalyst effect is high.
[0025]
The amount of the n-alkylamine in the present invention is 0.2 to 10 parts by weight with respect to 100 parts by weight of the diene rubber from the viewpoint that the catalytic effect is sufficiently exhibited and the rubber is not burned. However, it is preferably 0.2 to 5 parts by weight from the viewpoint of maintaining workability, and more preferably 0.2 to 3 parts by weight from the viewpoint of economy.
[0026]
As the kneading conditions in the step (a), first, the temperature is 120 ° C. or less from the point of selectively reacting only silica and the silane coupling agent, but from the point of increasing the efficiency of the reaction, A temperature of 80 to 120 ° C. is preferable, and a temperature of 80 to 115 ° C. is particularly preferable from the viewpoint of allowing a selective reaction.
[0027]
The kneading time is not particularly limited as long as the above-described components are uniformly dispersed, but is preferably 2 to 8 minutes from the viewpoint of sufficiently performing the reaction (silica and silane coupling agent). Further, it is particularly preferably 3 to 8 minutes from the viewpoint of sufficiently dispersing silica.
[0028]
The kneading means in this case is not particularly limited as long as it is conventional, and for example, a closed kneader such as a Banbury mixer or a kneader, an open roll or the like may be used.
[0029]
Next, in the step (b) of the present invention, other additives excluding the vulcanizing agent and the vulcanization accelerator are added to the kneaded product, and then the temperature in the step (a) is increased to a temperature of 160 ° C. or higher. Knead while heating.
[0030]
Other additives excluding vulcanizing agents and vulcanization accelerators include fillers such as carbon black, talc and clay, softeners such as paraffinic, aromatic and naphthenic process oils, coumarone indene resins, Examples thereof include tackifiers such as rosin resins and cyclopentadiene resins, and antiaging agents.
[0031]
The amount of these additives can be appropriately selected by those skilled in the art within a range not impairing the effects of the present invention. In addition, what is necessary is just to use for the kneading | mixing of a process (b) as it is, the kneaded material obtained by the process (a), when these additives are not included.
[0032]
As the kneading conditions in the step (b), the kneading is preferably performed at a temperature of 160 ° C. or higher and a temperature of 160 to 180 ° C. from the viewpoint that processability can be maintained.
[0033]
The kneading time may be 2 to 8 minutes from the viewpoint of sufficiently raising the temperature, and is preferably 2 to 6 minutes from the viewpoint of good workability.
[0034]
Moreover, what is necessary is just to knead | mix using the means used at the process (a) also in the process (b). For example, the kneaded material kneaded in the step (a) may be once discharged from the kneader used in the step (a) and then transferred to another kneader and kneaded in the step (b). Further, the step (a) and the step (b) may be continuously performed in the same kneader without performing the discharging operation in the step (a).
[0035]
Thus, the rubber composition of the present invention can be obtained. In the rubber composition of the present invention, a vulcanizing agent such as sulfur and peroxide, vulcanized so that it can be vulcanized after step (b). Accelerators, vulcanization aids such as stearic acid and zinc oxide may be added (step (c)).
[0036]
In this case, the blending amounts of the vulcanizing agent, the vulcanization accelerator, and the vulcanizing auxiliary agent may be the same as in the past, and may be within a range not impairing the effects of the present invention. The kneading conditions may be the same as before. Furthermore, the vulcanization method and conditions may be the same as before.
[0037]
The rubber composition of the present invention after vulcanization obtained as described above can be suitably used for a tire tread.
[0038]
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
[0039]
【Example】
Examples 1-4
According to the blending ratio and kneading conditions shown in Table 1, first, a diene rubber, silica, silane coupling agent, and n-alkylamine were kneaded and discharged using a 1.7 liter hermetic Banbury mixer. (Step (a)), and then kneaded using the same 1.7 liter Banbury mixer (Step (b)) to obtain a rubber composition of the present invention.
[0040]
Next, 1.5 parts by weight of a vulcanizing agent (sulfur), a vulcanization auxiliary (3 parts by weight of zinc white and 2 parts by weight of stearic acid) and a vulcanization accelerator using an open roll are added to the rubber composition of the present invention. (1 part by weight of NS and 0.5 part by weight of PPG) were mixed to obtain an unvulcanized rubber composition. This unvulcanized rubber composition was vulcanized at 170 ° C. for 15 minutes to obtain a rubber composition 1 of the present invention after vulcanization.
[0041]
The diene rubber is SBR1502 manufactured by Sumitomo Chemical Co., Ltd., the silica is Ultrazil VN3 granule type manufactured by Degussa, the silane coupling agent is Si69 manufactured by Degussa, and the n-alkylamine is n-. Butylamine, n-hexylamine, n-cetylamine, and n-stearylamine were used.
[0042]
The following evaluation was performed about the obtained rubber composition.
[0043]
[Test method]
(1) Mooney viscosity: The rubber composition before vulcanization was measured according to JIS K6300.
[0044]
▲ 2 ▼ Tensile Test: For the rubber composition after vulcanization, in accordance with JIS K6301, to prepare a sample in the form of No. 3 dumbbell, subjected to tensile test at a pulling speed of 500mm / min, M100, M300, T B, E _B and H _s were measured.
[0045]
(3) Loss tangent (tan δ): Using a VES-FIII2 manufactured by Iwamoto Seisakusho, tan δ was measured at a frequency of 10 Hz at 0 ° C. (strain ± 0.25%) and 70 ° C. (strain ± 1%). . The larger the value of tan δ at 0 ° C, the better the wet performance, and the smaller the value of tan δ at 70 ° C, the better the rolling resistance.
[0046]
(4) Lambourne abrasion test: The volume loss of the rubber composition was calculated under the conditions of a temperature of 23 ° C., a load of 2 kg, a slip rate of 20%, a sandfall amount of 20 g / min, and a test time of 5 minutes. Assuming that the loss amount of Comparative Example 1 described later is 100, the following formula
(Abrasion index) = {(loss amount in Comparative Example 1) / (loss amount in Example)} × 100
More indexed and evaluated. The higher the index, the better the wear resistance.
[0047]
(5) Wet skid test: Measured according to ASTM E303-83 method using a portable skid tester manufactured by Stanley. The resulting value (index) is the following formula:
(Wet skid index) = {(Index in Example) / (Index in Comparative Example 1)} × 100
Was evaluated as an index. The larger the index, the better the wet skid performance.
[0048]
The results of the test are summarized in Table 1.
[0049]
Comparative Example 1
A comparative rubber composition 1 was obtained in the same manner as in Example 1, except that only the step (a) was kneaded under the conditions shown in Table 1, and the same test as in Example 1 was performed. The results are shown in Table 1.
[0050]
Comparative Example 2
A comparative rubber composition 2 was obtained in the same manner as in Example 1 except that the conditions in step (a) and step (b) were changed to those shown in Table 1, and the same test as in Example 1 was performed. The results are shown in Table 1.
[0051]
Comparative Example 3
A comparative rubber composition 3 was obtained in the same manner as in Comparative Example 2 except that n-eicosylamine was used in place of n-alkylamine, and the same test as in Example 1 was performed. The results are shown in Table 1.
[0052]
[Table 1]

[0053]
From Table 1, it can be seen that by performing two-stage kneading under specific conditions, the Mooney viscosity is reduced, the workability is improved, and the wear resistance, wet skid resistance, and rolling resistance are improved.
[0054]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the rubber composition for tire tread excellent in low rolling resistance (low fuel consumption property) and wet performance can be obtained by improving the reaction efficiency of a silica and a silane coupling agent.

Claims (2)

(A) a diene rubber, silica, a silane coupling agent, and an n-alkylamine having 3 to 18 carbon atoms are kneaded at a temperature of 120 ° C. or less to obtain a kneaded product, and then (b) a vulcanizing agent, A rubber composition obtained by adding other additives excluding a vulcanization auxiliary and a vulcanization accelerator to the kneaded product and kneading at a temperature of 160 ° C. or higher. (A) a step of kneading a diene rubber, silica, a silane coupling agent, and an n-alkylamine having 3 to 18 carbon atoms at a temperature of 120 ° C. or lower to obtain a kneaded product, and (b) a vulcanizing agent. A method for producing a rubber composition comprising a step of kneading at a temperature of 160 ° C. or higher after adding other additives excluding a vulcanization aid and a vulcanization accelerator to the kneaded product.