JPS62129326A - Carbon black wet masterbatch - Google Patents

Abstract

PURPOSE:A masterbatch, consisting of a bale prepared by blending a styrene- butadiene copolymer with fine particulate carbon black and extender oil, having improved blending a processability and capable of giving a rubber composition for racing tires having good dispersibility. CONSTITUTION:A masterbatch, consisting of a bale prepared by blending (A) 100pts.wt., expressed in terms of solid, latex of a styrene-butadiene copolymer with >=30wt% combined styrene content, with (B) 80-150pts.wt. ultrafine particulate carbon black having >=150m<2>/g nitrogen specific surface area and >=100ml/100g DBP oil absorption and (C) 50-130pts.wt. extender oil having >=0.90 viscosity specific gravity constant (V.G.C.) and satisfying formulas I and II [W is the weight of the bale (g); V is the volume of the bale (l); beta is the amount of the component (B) blended in the bale (pts.wt.); r is the amount of the component (C) blended in the bale (pts.wt.); A is the specific gravity of the rubber latex; B is the specific gravity of the component (B); C is the specific gravity 15/4 deg.C of the component (C)].

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention is directed to a carbon black wet master bunch (hereinafter referred to as W-CBMB) capable of obtaining a rubber composition having excellent mixing processability and good carbon black dispersibility. related to).

[Prior art]

Traditionally, cap tread compounds for high-performance tires,
For cap tread compounds for competition tires, styrene-butadiene copolymer rubber (hereinafter referred to as SBR) with a styrene content of 30% by weight or more is generally used as a polymer, and a nitrogen specific surface area of 150 m''/g or more,
Contains more than 90 parts by weight of ultrafine carbon black with a DBP oil absorption of 100ml/100g or more,
Furthermore, due to the required characteristics of the compound, aromatic process oils, resins, etc. are also blended in large amounts in the same way as carbon black. However, such compounds have poor mixing processability compared to regular cap tread compounds;
Only mixtures with poor carbon black dispersion can be obtained. As a countermeasure to this problem, as shown in JP-A-58-1734 and JP-A-59-49247, W-CBMB, which is obtained by pre-mixing a rubber component, other compounding agents, and carbon black by a wet method, is used. It will be done. W-CBMB is generally made by adding a compounding agent such as carbon black to rubber latex in order to uniformly disperse carbon black into the rubber, mixing and coagulating it, and compressing this coagulate into a bale form. be. The bale is a lump of about 50 to 70 cm long x 30 to 40 cffi wide x 7 to 10 cffl high (Hale weight: 15
~50kg).

However, SB with a styrene content of 30% by weight or more
R is a rubber component, nitrogen specific surface area is 150 m27 g or more, and DBP oil absorption is 100 m j! W-CBMB, which is a mixture of ultrafine carbon black of /100 g or more, aromatic process oil, and high viscosity extension oil, has a mixing ratio of carbon black and oil that can be manufactured as W-CBMB due to the rubber components and the properties of carbon black. In this range, the disadvantage is that the W-CBMB has high rigidity.

For this purpose, W-CBM is prepared using a Banbury mixer or the like.
When mixing B and other compounding agents to produce a rubber composition for use as tire tread rubber, etc., (1) the strength limit of the machine is exceeded; (2) There are problems such as exceeding peak power.

Therefore, as a countermeasure, the amount of bonded styrene in the rubber component in W-CBMB is larger than that in normal SBR, and the viscosity decreases due to heat is large. A method is being taken.

However, such a method is not preferable in terms of energy saving and the like.

[Purpose of the invention]

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide W-CBMB with excellent mixing processability. This W-CBMB is particularly used as a rubber composition for cap treads for high-performance tires or competition tires.

[Structure of the invention]

Therefore, the present invention provides a nitrogen specific surface area of 150 m2 for 100 parts by weight of a styrene-butadiene copolymer rubber latex having a bound styrene content of 30% by weight or more as a solid content.
”/g or more and DBP oil absorption 100ml/10
0g or more ultrafine carbon plastic 80-150
Parts by weight, 50 to 130 parts by weight of an extender oil having a viscosity and specific gravity constant (V, G, C,) of 0.90 or more.
The gist of the present invention is a carbon black wet master hatch that satisfies the following formulas (1) and (2).

(W/V)/Sp, Gr≦0.85---(1)
BC W: Bale weight (kg) ■ = Bale volume (1) β: Carbon black content in the bale (parts by weight) γ:
Extender oil content in veil (parts by weight) A: Specific gravity based on rubber latex as a solid content B: Specific gravity of carbon black C: Specific gravity of extender oil (15/4°C) The structure of the present invention will be explained in detail below. do.

SB with a bound styrene content of 30% by weight or more used in the present invention
R latex is a latex obtained by emulsion polymerization or solution polymerization. In addition, nitrogen specific surface area 150m
”/g or more, and DBP oil absorption 100ml/1
00 g or more of ultrafine carbon black, for example,
Iodine adsorption amount 185 mg/g, DBP oil absorption amount 125 m shown in the example of JP-A No. 58-1734
l/100 g, tinting strength Tinttlh135 (IR
B No. 3 = 100) carbon black.

The W-CBMB of the present invention is prepared by adding 100 parts by weight of the SBR latex as a solid content and 80 parts by weight of the above carbon black.
A carbon black slurry obtained by dispersing ~150 parts by weight in water is added, and viscosity specific gravity constants (V, G,
C) It is obtained by blending 50 to 130 parts by weight of an extender oil of 0.90 or more, adding a coagulant to the resulting mixture, coagulating it, and drying this coagulated product, and having the formula above. (
1) and (2) are satisfied. In addition, in the above formula (1), 0.85 is used as the standard.
This is because the rigidity of the W-CBMB will increase if it exceeds . In the above formulas (11 and (2), 80≦β
≦150.50≦γ≦120.0.90≦A≦0.96
．． It is preferable that 1.78≦B≦1.85.0.90≦C≦1.05.

Examples and comparative examples are shown below.

Examples and Comparative Examples W-CBMB was produced by adding a coagulant to a mixture obtained by mixing the following raw materials (fat to fd), coagulating it, drying this coagulated product, and molding the obtained product. did.

(al SBR latex with a bound styrene content of 35% by weight.

(bl Carbon black slurry obtained by dispersing carbon black A in water.

(C) Carbon black slurry obtained by dispersing carbon black B in water.

(d+ Extender oil A.

In addition, the following numerical value was used regarding specific gravity.

■ Specific gravity based on solid content of SBR latex with bound styrene content of 35% by weight: 0.92°■ Specific gravity of carbon black: 1.82°■ Specific gravity of extender oil (15/4°C)
1.00° Also, regarding the blending amount, the solid content of SBR latex with a bound styrene content of 35% by weight is 100 parts by weight, and the above raw materials (carbon black, extender oil) are also shown in parts by weight.

Then, based on the above blending amount and specific gravity, the above formula (2)
Calculated using Therefore, in Example 1, formula (3)
Thus, Sp, Gr = 1, 158.

Next, the power peak height hl was determined as follows.

Usually, the purpose of using W-CBMB is (11) productivity to increase mixing efficiency and (2) quality and characteristics to maintain high dispersion of carbon black. Therefore,
Regardless of the purpose, the amount of carbon black and extender oil already blended into the W-CBMB is preferably close to that of the final rubber composition, and the amount of carbon black and extender oil already blended into the W-CBMB is preferably close to that of the final rubber composition. W-CBM
B will make up the majority of the final rubber composition.

Further, in the rubber composition using W-CBMB of the present invention, the filling rate is set relatively high and mixed.

Therefore, we decided to use a B-type Banbury mixer (manufactured by Kobe Steel, capacity 1).
．． 87 was used to cut the W-CBMB shown in Table 1 below so that the filling rate was 70%, and the rotor rotation speed was 4 Or.
p, m, casing and rotor are mixed at a temperature of 90°C, and the power peak height when W-CBMB is turned on is h.
1 was expressed as an index for each W-CBMB as shown in FIG. 1, with Example 1 being 100. Therefore, it can be seen from FIG. 1 that it is preferable that the smaller the value, the smaller the peak power. Moreover, regarding power consumption, the cumulative amount of power for 5 seconds from the time of power on is described.

(Margins below this page) Notes to Table 1: L1- 35% styrene content SBR latex
0.92 carbon black A (nitrogen specific surface area 163
0BP 116) 1.82 Carbon Black B
(Nitrogen specific surface area 200 DBP 126) 1.
82 Extension oil A (V, G, C, 0,96)
-1,00BC O,921,821,00 As can be seen from Comparative Example 1 and Example 1 in Table 1, the values of (W/V) /Sp and Gr were 0.88 despite the same formulation content. The power peak height hl of Comparative Example 1 is 100
Then, in Example 1 where the values of (W/V)/Sp and Gr are 0.75, (h) is 55, which significantly reduces the load on the Banbury mixer. Next, in Example 2, the first
As is clear from the table below, this is the case when carbon black with a larger nitrogen specific surface area is used, and in this case also (hl is 60, which is a smaller value than in Example 1). Example 3 is a case in which the blended amounts of carbon black and extender oil are further increased, and since the blended amount of carbon black is large, the W-CBMB has increased rigidity and the power peak height is higher than in Example 1. However, even in this case, the power peak height is significantly smaller than that of Comparative Example 1.Furthermore, in Example 4, compared to Example 3, the carbon black is carbon black A, but the extender oil A is The blended amount was reduced, and the power consumption for 5 seconds is equivalent to Example 3, but (W/V)/Sp,Gr = 0.68, which is small, so the power peak height hl is 50, (W/V)/Sp,Gr = 0.68. V)/S
It can be seen that reducing p and Gr is extremely effective in reducing the initial power peak height.

〔Effect of the invention〕

As explained above, according to the present invention, (W/V)/Sp
, by setting Gr≦0.85, the initial power peak height can be significantly reduced, and the power consumption for 5 seconds can also be reduced, so there are advantages such as (1) reduced burden on the mixer, (2) energy saving, etc. There is.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between power peak height and mixing time.

Claims (1)

[Scope of Claims] Based on 100 parts by weight of styrene-butadiene copolymer rubber latex having a bound styrene content of 30% by weight or more as a solid content, a nitrogen specific surface area of 150 m^2/g or more and D
80 to 150 parts by weight of ultrafine carbon black with a BP oil absorption of 100 ml/100 g or more, viscosity specific gravity constant (V.G.
．． C. ) A carbon black wet masterbatch comprising a veil containing 50 to 130 parts by weight of an extender oil of 0.90 or more, and satisfying the following formulas (1) and (2). (W/V)/Sp. Gr≦0.85 (1)
Sp. Gr=(100+β+γ)/(100/A+β/
B+γ/C)...(2) W: Bale weight (kg) V: Bale volume (l) β: Carbon black content in the veil (parts by weight) γ:
Extender oil content in veil (parts by weight) A: Specific gravity based on rubber latex as solid content B: Specific gravity of carbon black C: Specific gravity of extender oil (15/4°C)