JP2006213791A - Zinc flower-containing wet masterbatch, method for producing the same, and rubber composition and tire each using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber masterbatch having heat resistance, reinforcing properties, and abrasion resistance improved by improving the dispersibility of zinc flower in a rubber, to provide a method for producing the same, and to provide a rubber composition and a tire each using the same. <P>SOLUTION: What is provided is a method for producing a wet masterbatch which is a method for producing a zinc flower-containing wet masterbatch and comprises preparing slurry by previously dispersing a specified filler and zinc flower in a solution by means of a high-shear mixer, mixing the slurry with a rubber solution to coagulate the rubber; a rubber composition obtained by using the masterbatch; and a tire using the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a zinc white-containing wet masterbatch, and more particularly to a zinc white-containing wet masterbatch with improved reinforcement and wear resistance, a method for producing the same, and a rubber composition and a tire using the same.

Usually, in the rubber industry, zinc white is used as a vulcanization accelerating aid and indispensable for blending diene rubbers. This zinc flower usually has a primary particle size of 1 μm or less and is blended together with other compounding agents using a closed mixer such as a Banbury mixer or a kneader or an open roll, but the specific gravity of zinc flower is about 5 Since it is heavy and has high cohesiveness, it is difficult to obtain good dispersion in the rubber, and many agglomerates of several tens of μm are observed.
On the other hand, it is generally known that a wet masterbatch has good dispersibility of the filler and that excellent rubber properties can be obtained (Patent Documents 1 to 3). In these patent documents, it is described that a general rubber compounding agent can be added to the slurry solution used in the production of the wet masterbatch, but the dispersion method is not particularly described.

Japanese Patent Publication No.54-10576 Japanese Patent Publication No.51-43851 Japanese Patent Publication No.36-22729

  Under such circumstances, the present invention provides a rubber masterbatch having improved dispersibility of zinc white in rubber, improved reinforcement (breaking strength) and wear resistance, a method for producing the same, and a rubber composition using the same The object is to provide goods and tires.

As a result of diligent research, the present inventors have found that it is effective to disperse zinc white together with a predetermined filler using a high shear mixer in the slurry solution preparation process, and to mix this slurry solution with a rubber solution. The headline and the present invention were completed.
That is, the present invention has the following configuration.

1. A method for producing a wet masterbatch containing zinc white,
(A) (a) zinc white and (b) carbon black, silica, or general formula (I)
nM ₁ · xSiO _y · zH ₂ O (I)
[Wherein, M ₁ is selected from the group consisting of metals selected from aluminum, magnesium, titanium, calcium and zirconium, oxides or hydroxides of these metals, hydrates thereof, and carbonates of the metals. N, x, y and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10.] After preparing a slurry solution by simultaneously dispersing at least one filler with a high shear mixer,
(B) A method for producing a wet masterbatch, wherein the slurry solution and the rubber solution are mixed and solidified.
2. As the characteristics of the slurry solution, (i) the particle size distribution of the filler in the 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 masterbatch according to 1 above, wherein the 24M4DBP oil absorption amount of the filler recovered by drying from the slurry solution is maintained at 93% or more of the 24M4DBP oil absorption amount before being dispersed in the solution.
3. 3. The method for producing a wet masterbatch according to 1 or 2, wherein the rubber solution is natural rubber latex or synthetic rubber latex.
4). The manufacturing method of the wet masterbatch in any one of said 1-3 whose slurry solution is an aqueous dispersion solution.
5. 5. The method for producing a wet masterbatch according to any one of 1 to 4, wherein drying is performed while applying a mechanical shearing force in the step of drying the wet masterbatch after solidification.
6). 6. The method for producing a wet masterbatch according to 5 above, wherein drying is performed using a continuous kneader.
7). 7. The method for producing a wet masterbatch according to 6 above, wherein the continuous kneader is a multi-screw kneading extruder.
8). The wet masterbatch manufactured by the method in any one of said 1-7.
9. 9. A rubber composition using the wet masterbatch described in 8 above.
10. A tire using the rubber composition as described in 9 above.

  According to the present invention, it is possible to improve rubber reinforcement (breaking strength) and wear resistance by producing a master batch using a slurry in which zinc white is dispersed together with a predetermined filler by a high shear mixer. .

In the present invention, the wet masterbatch is manufactured by mixing a slurry solution containing zinc white and a predetermined filler and a rubber solution.
In the slurry solution preparation step (step A), the filler dispersed in the solution is carbon black, silica, and general formula (I).
nM ₁ · xSiO _y · zH ₂ O (I)
[Wherein M ₁ , n, x, y, and z are described above] is at least one selected from the group consisting of inorganic fillers.
Here, as carbon black, those usually used in the rubber industry can be used. For example, various grades of carbon black such as SAF, HAF, ISAF, FEF, and GPF can be used alone or in combination.
Silica is not particularly limited, but wet silica, dry silica, and colloidal silica are preferable.

Specific examples of the inorganic filler represented by the general formula (I) include alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina, and alumina monohydrate (Al ₂ O such as boehmite and diaspore). ₃ · H ₂ O), Gibbsite, Bayerite, etc. Aluminum hydroxide [Al (OH) ₃ ], Aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], Magnesium hydroxide [Mg (OH) ₂ ], Magnesium oxide ( MgO), magnesium carbonate (MgCO _3), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), titanium white (TiO _2), titanium black (TiO _2n-1), calcium oxide (CaO), calcium hydroxide [Ca (OH) _2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2 O 3 · 2SiO 2} ), Kao Down _{(Al 2 O 3 · 2SiO 2} · 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ · 3SiO ₄ · 5H ₂ O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate (Ca ₂ · SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O], carbonic acid zirconium _{[Zr (CO 3) 2]} , crystalline aluminosilicate containing hydrogen, alkali metal or alkaline earth metal which corrects a charge as various zeolites There can be used. The inorganic filler represented by the general formula (I), those of at least one of M ₁ is selected from aluminum metal, oxide or hydroxide of aluminum, carbonate of their hydrates and aluminum, Is preferred.

In preparing the slurry solution in the present invention, it is necessary to mix the above-mentioned predetermined filler together with zinc white in a dispersion solution and disperse using a high shear mixer.
Here, the high shear mixer is a high shear mixer including a rotor and a stator portion, and a rotor rotating at a high speed and a fixed stator are installed with a narrow clearance, and a high shear rate is generated by the rotation of the rotor.
High shear means that the shear rate is 2000 / s or more, preferably 4000 / s or more. Examples of commercially available high shear mixers include a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd., a colloid mill manufactured by PUC, a Cavitron manufactured by Cavitron, and a high shear mixer manufactured by Silverson UK.

As described above, the characteristics of the slurry solution obtained using the high shear mixer are as follows: (i) The particle size distribution of the filler in the slurry solution is a volume average particle size (mv) of 25 μm or less and 90 volume% particles. It is preferable that the diameter (D90) is 30 μm or less, and (ii) the 24M4DBP oil absorption amount of the filler recovered by drying from the slurry solution is 93% or more of the 24M4DBP oil absorption amount before being dispersed in the solution. . 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, if an excessive shearing force is applied to the slurry in order to reduce the particle size, the structure of the filler may be destroyed and the reinforcing property may be lowered. It is desirable 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.
In the slurry solution, the concentration of the filler is preferably 1 to 15% by mass, and particularly preferably in the range of 2 to 10% by mass. When the concentration of the filler is less than 1% by mass, the required slurry volume becomes too large, and when it is 15% by mass or more, the viscosity of the slurry solution becomes too high, causing problems in operation. The slurry solution is preferably an aqueous dispersion solution.

  Moreover, it is preferable that the density | concentration of zinc white is 0.1-2 mass% in a slurry solution. If it is less than 0.1% by mass, the effect of improving the physical properties is not sufficient, and if it exceeds 2% by mass, the uniformity of zinc white concentration in the slurry solution may not be maintained.

Next, in step (B), the rubber solution mixed with the slurry solution includes natural or synthetic rubber latex, and also includes an organic solvent solution of synthetic rubber by solution polymerization. Of these, natural or synthetic rubber latex is preferred.
As the natural rubber latex, any of field latex, ammonia-treated latex, centrifugal concentrated latex, deproteinized latex treated with a surfactant or 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 are mixed by, for example, putting the slurry solution in a homomixer and dropping the latex while stirring, or conversely dropping the slurry solution while stirring the latex. There is a way to do it. Also, a method of mixing a slurry flow having a constant flow rate and a latex flow under conditions of vigorous hydraulic stirring can be used.

  The wet masterbatch is solidified by using a solidifying agent such as formic acid or sulfuric acid or a salt such as sodium 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 wet 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 the filler, a mechanical shearing force is applied. It is preferable to perform drying.
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 wet master batch obtained by the above method. To the rubber composition, various chemicals usually used in the rubber industry such as a vulcanizing agent, a vulcanization accelerator, an antiaging agent, an anti-scorching agent, and stearic acid may be added within a range not impairing the object of the present invention. Can do.
Moreover, in this rubber composition, it is preferable that the rubber component in the said wet masterbatch is 30 mass% or more with respect to the whole rubber component. Examples of other rubber components used in addition to the wet masterbatch 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 a tire rubber, and can be applied to all tire members such as tread rubber, side rubber, ply coating rubber, bead filler rubber, belt coating rubber, and the like.

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 filler 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 re-aggregation of the filler, measurement was performed immediately after dispersion.
(2) 24M4DBP oil absorption of the filler Measured according to ISO 6894.

(3) Fracture strength test Based on JIS K6251-1993, the tensile strength when measured at 23 degreeC was calculated | required. The greater the value, the higher the reinforcement.
(4) Lambourn Abrasion Resistance Test Using a Lambourn 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.

<Manufacture of wet masterbatch and preparation of rubber composition>
Example 1
As the preparation of the slurry solution, carbon black (N110) and zinc white were put in water at a ratio of 5% by mass and 0.3% by mass, respectively, and finely dispersed with a high shear mixer manufactured by Silverson Co., to prepare a slurry solution. . The particle size distribution of the carbon black in the slurry obtained here was a center particle size mv = 13.1 μm and D90 (90% particle size) = 18.3 μm.
Next, 3 kg of the slurry solution and 3 kg of natural rubber concentrated latex diluted to 10% by mass were mixed with stirring, solidified by controlling to pH 4.5 with formic acid, washed, and then washed with a twin-screw extruder ((stock ) Drying was performed with Kobe Steel KTX30) to obtain a wet masterbatch A.
In the wet master batch A, the amount of carbon black per 100 parts by mass of rubber was 50 parts by mass, and the amount of zinc white was 3 parts by mass.
The obtained wet masterbatch was blended according to the formulation shown in Table 1 using a Banbury mixer and vulcanized at 150 ° C. for 30 minutes to obtain a rubber composition (a).

Comparative Example 1
A rubber composition (b) was obtained by blending according to the formulation shown in Table 1 using a Banbury mixer and vulcanizing at 150 ° C. for 30 minutes.
Comparative Example 2
As a preparation of the slurry solution, a slurry solution was prepared in the same manner as in Example 1 except that it was prepared without adding zinc white.
Next, 3 kg of the slurry solution and 3 kg of natural rubber concentrated latex diluted to 10% by mass were mixed, and wet masterbatch B was prepared in the same manner as in Example 1.
In the wet master batch B, the carbon black per 100 parts by mass of rubber was 50 parts by mass.
The obtained wet masterbatch was blended according to the formulation shown in Table 1 using a Banbury mixer, and vulcanized at 150 ° C. for 30 minutes to obtain a rubber composition (c).

<Evaluation of rubber composition>
Further, the vulcanized rubber compositions (a) to (c) obtained above were measured for fracture strength and Lambourne abrasion resistance. The results are shown in Table 1.

(note)
Anti-aging agent 6C: N- (1,3-dimethylbutyl) -N`-phenyl-p-phenylenediamine vulcanization accelerator NS: Nt-butyl-2-benzothiazylsulfenamide

  According to the above results, although Comparative Example 2 using a wet masterbatch that does not contain zinc white is improved in breaking strength and wear resistance compared to Comparative Example 1 using ordinary dry blending, its effect is In contrast, Example 1 according to the present invention shows a significant improvement in fracture strength and wear resistance.

The use of a rubber masterbatch having improved dispersibility of zinc white in rubber and improved reinforcement (breaking strength) and wear resistance is particularly useful for applications such as tires.

Claims (10)

A method for producing a wet masterbatch containing zinc white,
(A) (a) zinc white and (b) carbon black, silica, or general formula (I)
nM ₁ · xSiO _y · zH ₂ O (I)
[Wherein M ₁ comprises a metal selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, an oxide or hydroxide of these metals, a hydrate thereof, and a carbonate of the metal. At least one selected from the group, and n, x, y and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10]. After preparing the slurry solution by simultaneously dispersing at least one filler of the filler using a high shear mixer,
(B) A method for producing a zinc white-containing wet masterbatch, wherein the slurry solution and the rubber solution are mixed and solidified. As the characteristics of the slurry solution, (i) the particle size distribution of the filler in the 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 masterbatch according to claim 1, wherein the 24M4DBP oil absorption amount of the filler recovered by drying from the slurry solution is maintained at 93% or more of the 24M4DBP oil absorption amount before being dispersed in the solution. The method for producing a wet masterbatch according to claim 1 or 2, wherein the rubber solution is natural rubber latex or synthetic rubber latex. The method for producing a wet masterbatch according to any one of claims 1 to 3, wherein the slurry solution is an aqueous dispersion solution. The method for producing a wet masterbatch according to any one of claims 1 to 4, wherein drying is performed while applying a mechanical shearing force in the step of drying the wet masterbatch after solidification. The manufacturing method of the wet masterbatch of Claim 5 which performs drying using a continuous kneader. The method for producing a wet masterbatch according to claim 6, wherein the continuous kneader is a multi-screw kneading extruder. The wet masterbatch manufactured by the method in any one of Claims 1-7. A rubber composition using the wet masterbatch according to claim 8. A tire using the rubber composition according to claim 9.