JP4726507B2 - Rubber masterbatch and production method thereof, and rubber composition and tire using the same - Google Patents

Description

  The present invention relates to a rubber masterbatch, and more particularly, a silica / rubber masterbatch comprising a specific surface-treated silica and having excellent wear resistance and high storage modulus, a method for producing the same, a rubber composition using the same, and Regarding tires.

In general, it is known that silica has a surface covered with hydrophilic silanol groups and has poor dispersibility in rubber due to aggregation due to hydrogen bonding. For this reason, as a method for improving dispersibility, wet master batches using silica have been conventionally known (Patent Document 1, Patent Document 2, etc.).
Further, a technique for improving dispersibility by treating a silica surface with a silane coupling agent or the like to make it hydrophobic is known and widely used in the rubber industry. For example, Patent Document 3 discloses a master batch by adding silica treated with a silane coupling agent having a specific structure to a polymer latex. Patent Document 4 discloses a rubber wet masterbatch containing silica and carbon black hydrophobized with a silane coupling agent. Patent Document 5 discloses a solution polymerization SBR masterbatch containing silica that has been submerged with a silane coupling agent.

However, the silica treated with the silane coupling agent by the above technique generates an alcohol by condensation during the treatment or in the subsequent process, and has a safety problem. In addition, the storage elastic modulus (E ′) was lowered and there was a problem in rubber physical properties.
Further, Patent Document 6 discloses a filler-containing rubber powder produced through a process of suspending polysiloxane using a surfactant and treating it with a silica slurry. However, in this case, although the dispersibility of the filler is improved, since the silica surface and the polysiloxane do not react, it is not possible to expect improvement in rubber properties such as wear resistance.

JP-A-53-81546 WO2002 / 020655 publication Japanese Patent Laid-Open No. 10-231331 JP 2000-1547 A Japanese translation of PCT publication No. 2002-5155158 JP 2003-160668 A

  Under such circumstances, the present invention improves the affinity between rubber molecules and silica, and has a silica / rubber masterbatch having excellent wear resistance and high storage elastic modulus (E`), a method for producing the same, and a method for producing the same. The object is to provide a rubber composition and a tire used.

As a result of intensive studies, the present inventors have found that it is effective to produce a rubber masterbatch using silica surface-treated with a specific polysiloxane, and have completed the present invention.
That is, the present invention has the following configuration.
1. (A) The following general formula (I)

[Wherein, X is any one selected from the group consisting of hydrogen, phenyl group, amino group, mercapto group and alkyl group, and 0 ≦ m ≦ 1000 and 0 ≦ n ≦ 1000. ]
Silica whose surface was treated at a temperature of 100 ° C. or higher using 0.5 to 7% by mass of the compound represented by
(B) The manufacturing method of the rubber masterbatch characterized by mixing the said slurry solution and a rubber solution.
2. As the characteristics of the slurry solution, (i) the particle size distribution of silica in the water-dispersed slurry solution has a volume average particle size (mv) of 25 μm or less, a 90 volume% particle size (D90) of 30 μm or less, and (Ii) The method for producing a rubber masterbatch according to 1 above, wherein the 24M4DBP oil absorption amount of silica recovered by drying from the water-dispersed slurry solution is maintained at 93% or more of the 24M4DBP oil absorption amount before being dispersed in water.
3. The method for producing a rubber masterbatch according to claim 1 or 2, wherein the rubber solution is natural rubber latex and / or synthetic rubber latex.
4. The method for producing a rubber master batch according to 1 to 3, wherein the silica is any one of wet silica, dry silica, and colloidal silica.
5. The method for producing a rubber master batch according to any one of 1 to 4, wherein drying is performed while applying a mechanical shearing force in the step of drying the rubber master batch after coagulation.
6. The method for producing a rubber master batch according to 5 above, wherein drying is performed using a continuous kneader.
7. The method for producing a rubber master batch according to 6 above, wherein the continuous kneader is a double-screw kneading extruder.
8). The rubber masterbatch manufactured by the method in any one of said 1-7.
9. 9. A rubber composition using the rubber master batch according to 8 above.
10. The rubber composition as described in 9 above, further comprising a silane coupling agent.
11. A tire using the rubber composition as described in 10 above.

  According to the present invention, in the production of a rubber masterbatch, silica treated with a specific compound is used in a slurry solution, so that the wettability between silica and rubber molecules is remarkably improved, and the wear resistance and storage elastic modulus of rubber. And can be greatly improved.

In the present invention, silica that has been surface-treated with a specific polysiloxane compound under a certain heat treatment condition is used as the filler of the slurry.
As this specific polysiloxane compound, the following general formula (I)

It is necessary to be a compound represented by Although there is no restriction | limiting in particular as silica, Any of wet silica, dry silica, and colloidal silica is preferable.
In the general formula (I), X is any one selected from hydrogen, a phenyl group, an amino group, an alkyl group, and a mercapto group. The alkyl group preferably has 2 to 20 carbon atoms. m is 0 ≦ m ≦ 1000, preferably 2 ≦ m ≦ 500. n is 0 ≦ n ≦ 1000, preferably 0 ≦ n ≦ 500.
In the general formula (I), the repeating structure of m and the repeating structure of n may be block, random, or alternating. If there is no problem in fluidity, a branched structure may be used.

The surface-treated silica is not particularly limited, but any of wet silica, dry silica, and colloidal silica is preferable. When surface-treating silica, the compound represented by the general formula (I) needs to be in the range of 0.5 to 7% by mass of the amount of silica. If the amount is less than 0.5% by mass, a sufficient surface treatment effect cannot be obtained. If the amount exceeds 7% by mass, the storage elastic modulus tends to decrease and the production of the slurry becomes difficult.
Furthermore, in the present invention, the surface treatment of silica with the compound represented by the general formula (I) requires a heat treatment at 100 ° C. or higher. Specifically, the surface treatment of silica is preferably performed at 150 ° C. or more, more preferably 250 after mixing the polysiloxane compound (silicone oil and modified silicone oil) represented by the general formula (I) using a Henschel mixer or the like. It can be obtained by heat treatment at a temperature of ˜350 ° C. Furthermore, a catalyst such as KOH, (CH ₃ ) NOH, (n—C ₄ H ₉ ) ₄ POH, sulfuric acid, hydrochloric acid, or the like may be used during this heat treatment.
In this way, the silicone oil molecules are cleaved by the heat treatment and chemically bonded to the silica, so that the wettability with the rubber molecules is dramatically improved, and the high wear resistance and the storage elastic modulus (E ′) are increased. can get.

    In the present invention, in the step (A), the surface-treated silica is dispersed in water to produce a slurry solution. The manufacturing method can be performed using a known method and is not particularly limited. A rotor / stator type high shear mixer, high-pressure homogenizer, ultrasonic homogenizer, colloid mill, or the like may be used. For example, it can be prepared by putting water and the surface-treated silica in a colloid mill and stirring at high speed.

The properties of the slurry solution thus obtained are as follows: (i) The particle size distribution of the filler in the water-dispersed slurry solution has a volume average particle size (mv) of 25 μm or less and a 90 volume% particle size (D90). It is preferably 30 μm or less, and (ii) the 24M4DBP oil absorption amount of the filler dried and recovered from the water-dispersed slurry solution is adjusted to maintain 93% or more of the 24M4DBP oil absorption amount before being dispersed in water. . Here, the 24M4DBP oil absorption is a value measured according to ISO 6894.
More preferably, the volume average particle diameter (mv) is 20 μm or less, and the 90 volume% particle diameter (D90) is 25 μm or less. If the particle size is too large, the filler dispersion in the rubber may be deteriorated, and the reinforcement and wear resistance may be deteriorated.

On the other hand, when an excessive shearing force is applied to the slurry in order to reduce the particle size, the structure of the filler tends to be destroyed and the reinforcing property tends to be lowered. It is preferable that the 24M4DBP oil absorption amount of the filler recovered by drying from the slurry solution is 93% or more of the 24MDBP oil absorption amount of the filler before being charged into the slurry. More preferably, it is 96% or more.
The concentration of the silica in the slurry solution is preferably 1 to 15% by mass, and more preferably 2 to 10% by mass. If it is less than 1% by mass, the required slurry volume becomes too large, and if it is 15% by mass or more, the viscosity of the slurry solution becomes too high, causing problems in operation.

Next, in the step (B), the rubber solution mixed with the slurry solution includes natural rubber latex and / or synthetic rubber latex, and also includes an organic solvent solution of synthetic rubber by solution polymerization. Of these, natural rubber latex and / or synthetic rubber latex are preferred.
As the natural rubber latex, any of field latex, ammonia-treated latex, centrifugal concentrated latex, deproteinized latex treated with an enzyme, and a combination of the above-mentioned ones can be used.
Examples of the synthetic rubber latex include latexes such as styrene-butadiene polymer rubber, nitrile rubber, and polychloroprene rubber.

The slurry solution and the rubber solution can be mixed, for example, by placing the slurry solution in a homomixer and stirring the rubber solution (for example, latex, the same applies hereinafter) while stirring the rubber solution. However, there is a method of dropping the slurry solution. Also, a method of mixing a slurry flow having a constant flow rate ratio and a rubber solution flow under conditions of vigorous hydraulic stirring can be used.
As a method for coagulating the master batch, it is carried out using a coagulant such as formic acid and sulfuric acid, and a salt such as sodium chloride and aluminum chloride as usual. In the present invention, coagulation may be achieved by mixing natural rubber latex and the slurry without adding a coagulant.

  Drying is usually performed as the final step of master batch production. In the present invention, a normal dryer such as a vacuum dryer, an air dryer, a drum dryer, or a band dryer can be used. In order to further improve the dispersibility of silica, drying is performed while applying mechanical shearing force. Is preferably performed. Thereby, in the case of rubber | gum, workability, reinforcement, etc. can be improved more. Although this drying can be performed using a general kneader, it is preferable to use a continuous kneader from the viewpoint of industrial productivity. Furthermore, it is more preferable to use a multi-screw kneading extruder that rotates in the same direction or in different directions.

The rubber composition of the present invention is obtained by blending the master batch obtained by the above method.
It is preferable that a silane coupling agent is further added to the rubber composition. Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, and bis (2-triethoxy). Silylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyl Trimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthioca Vamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzoyl tetrasulfide, 3-triethoxy Silylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetra Sulfide, dimethoxymethylsilylpropylbenzothiazolyl tetrasulfide, and the like. Among these, bis (( - triethoxysilylpropyl) polysulfide and 3-trimethoxysilylpropyl benzothiazyl tetrasulfide are preferable. These silane coupling agents may be used individually by 1 type, and may be used in combination of 2 or more types.

Various chemicals usually used in the rubber industry such as a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, an anti-scorching agent, and stearic acid are added to the rubber composition as long as the object of the present invention is not impaired. Can do.
Moreover, in this rubber composition, it is preferable that the rubber component in the said masterbatch is 30 mass% or more with respect to the whole rubber component. Examples of other rubber components used in addition to the master batch include ordinary natural rubber and diene synthetic rubber. Examples of the diene synthetic rubber include styrene-butadiene copolymer (SBR) and polybutadiene (BR). ), Polyisoprene (IR), butyl rubber (IIR), ethylene-propylene copolymer, and mixtures thereof.

  The rubber composition of the present invention can be used not only for tire applications but also for applications such as anti-vibration rubber, belts, hoses and other industrial products. In particular, it is suitably used as tire rubber, and can be applied to all tire members such as tread rubber, side rubber, ply coating rubber, bead filler rubber, and belt coating rubber.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
Various measurements in each example and comparative example were performed as follows.
(1) Measurement of particle size distribution of silica in slurry solution (volume average particle diameter (mv), 90 volume% particle diameter (D90))
A laser diffraction particle size distribution meter (MICROTRAC FRA type) was used, and measurement was performed using an aqueous solvent (refractive index: 1.33). A particle refractive index of 1.57 was used for all measurements. Further, in order to prevent reaggregation of silica, measurement was performed immediately after dispersion.
(2) 24M4DBP oil absorption of silica Measured according to ISO 6894.
(3) Abrasion resistance Using a Ramborn type abrasion tester, the amount of wear was measured at a slip rate of 40% at room temperature, and the reciprocal thereof was expressed as an index with the rubber composition of Comparative Example 1 as 100. The larger the value, the less the weight loss and the better the wear resistance.
(4) Storage elastic modulus (E ')
Measurement was performed at 60 ° C. and 52 Hz with an amplitude of 1% using a Toyo Seiki Rheograph Solid.

<Manufacture of master batch>
Example 1
(A) Silica Surface Treatment and Preparation of Slurry Solution 3% by mass of polydimethylsiloxane having a polymerization degree of 50 is added to wet silica (nipseal VN3) with respect to silica, and vigorously stirred at 270 ° C. for 30 minutes using a Henschel mixer. A surface-treated silica was obtained.
Water was added so that the above-mentioned surface-treated silica became a 5% by mass slurry, and treated at 8000 rpm for 30 minutes using a colloid mill (rotor diameter 50 mm) to obtain a uniform slurry.
(B) Production of rubber masterbatch Commercially available natural rubber concentrated latex (concentration 60% by mass, ammonia concentration 0.7% by mass) was diluted so that the rubber concentration was 20% by mass, and the above slurry was stirred while stirring 2000 g. 4000 g was added and formic acid was added until the pH reached 4.5 to obtain a solidified rubber.
The coagulated rubber was dehydrated until the water content was about 30%, and then dried with a twin screw extruder to obtain a rubber master batch C having 50 parts of treated silica.

Example 2
A rubber masterbatch D was obtained in the same manner as in Example 1 except that polydimethylsiloxane was used in the general formula, where X is hydrogen, m = 140, and n = 60. .
Comparative Example 1
A rubber master batch A was obtained in the same manner as in Example 1 except that untreated silica was used.
Comparative Example 2
In Example 1, rubber masterbatch B was obtained in the same manner as in Example 1 except that the amount of polysiloxane with respect to silica was changed to “10% by mass” instead of “3% by mass”.

<Evaluation of rubber composition>
Comparative Example 3
Silica VN3 powder was blended by ordinary dry blending. That is, after blending according to the blending shown in Table 1 with a Banbury mixer, vulcanization was performed at 150 ° C. for 30 minutes to obtain a rubber composition. About this thing, abrasion resistance and storage elastic modulus (E ') were measured. The results are shown in Table 1.
Examples 3 and 4 and Comparative Examples 3 to 5
The silica / rubber master batches A to D obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were blended according to the formulation shown in Table 1 with a Banbury mixer, and vulcanized at 150 ° C. for 30 minutes for a rubber composition. Were measured for wear resistance and storage modulus (E ′). The results are shown in Table 1.

(note)
Silica VN3: Toso Silica Co., Ltd. Silane coupling agent Si69: Degussa anti-aging agent 6C: N- (1,3-dimethylbutyl) -N`-phenyl-p-phenylenediamine vulcanization accelerator DPG : Diphenylguanidine vulcanization accelerator NS: Nt-butyl-2-benzothiazylsulfenamide

  According to said result, in Example 3, 4 using the silica containing rubber masterbatch in this invention, the outstanding improvement of the abrasion resistance and the storage elastic modulus (E ') increase is seen. On the other hand, in Comparative Example 4 using a master batch of untreated silica and in Comparative Example 5 in which polysiloxane was added in excess of 7% by mass in Example 1, the storage elastic modulus E ′ was greatly reduced. .

The use of a rubber masterbatch that increases the affinity of silica for rubber and has excellent wear resistance and high storage modulus (E ′) is particularly useful for applications such as tires.

Claims (11)

(A) The following general formula (I)

[Wherein, X is any one selected from the group consisting of hydrogen, phenyl group, amino group, mercapto group and alkyl group, and 0 ≦ m ≦ 1000 and 0 ≦ n ≦ 1000. ]
Silica surface-treated at a temperature of 100 ° C. or higher using 0.5 to 7% by mass of the compound represented by formula (1) is dispersed in water to form a slurry solution,
(B) The manufacturing method of the rubber masterbatch characterized by mixing the said slurry solution and a rubber solution.   As the characteristics of the slurry solution, (i) the particle size distribution of silica in the water-dispersed slurry solution has a volume average particle size (mv) of 25 μm or less, a 90 volume% particle size (D90) of 30 μm or less, and (ii 2. The method for producing a rubber masterbatch according to claim 1, wherein the 24M4DBP oil absorption amount of silica dried and recovered from the aqueous dispersion slurry solution is maintained at 93% or more of the 24M4DBP oil absorption amount before being dispersed in water. The method for producing a rubber masterbatch according to claim 1 or 2, wherein the rubber solution is natural rubber latex and / or synthetic rubber latex.   The method for producing a rubber masterbatch according to claims 1 to 3, wherein the silica is any one of wet silica, dry silica, and colloidal silica.   The method for producing a rubber masterbatch according to any one of claims 1 to 4, wherein drying is performed while applying mechanical shearing force in the step of drying the rubber masterbatch after coagulation.   The manufacturing method of the rubber masterbatch of Claim 5 which performs drying using a continuous kneader.   The method for producing a rubber masterbatch according to claim 6, wherein the continuous kneader is a double-screw kneading extruder.   The rubber masterbatch manufactured by the method in any one of Claims 1-7.   A rubber composition using the rubber master batch according to claim 8.   Furthermore, the rubber composition of Claim 9 containing a silane coupling agent. A tire using the rubber composition according to claim 10.