JPH0232136A - Carbon black for blending of tire tread rubber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to carbon black for tire tread rubber, which can impart high wear resistance and relatively low heat build-up to a rubber component.

[Conventional technology]

Conventionally, the specific surface area (particle size) and struture of carbon blanks have been considered to be the dominant factors in the rubber reinforcement performance of carbon blanks, and there are various types of carbon blanks depending on their characteristics. When blending with the rubber component, carbon black with variety characteristics that match the application material is selected and used.For example, a high degree of abrasion resistance is required under harsh driving conditions, such as in tire treads. For rubber parts,
Hard carbon black such as Nll01N220 is used.

However, in recent years, as tire running has become more severe, the performance required of tire treads has also become more sophisticated, and it is particularly important to have both high wear resistance and low heat generation.

In general, the larger the specific surface area or stracture of carbon black, the higher the abrasion resistance, but on the other hand, the higher the heat generation property, and there is a trade-off between these two properties. Therefore, it is extremely difficult to simultaneously impart high abrasion resistance and low heat build-up to a rubber composition.

In order to solve this problem, various attempts have been made to apply carbon black having specific properties (Japanese Patent Publication No. 53-34149, Japanese Patent Application Laid-Open No. 63-112638, etc.).

[Problem to be solved by the invention]

However, the conventionally proposed rubber compositions containing carbon blanks with selective properties are still insufficient in maintaining wear resistance and heat generation properties at good levels.
Improvement of the layer is desired.

In order to solve the above-mentioned problems, as a result of repeated research from a different angle than the conventional technology, the present invention has developed a carbon blank having relatively large aggregate voids in an aggregate with a certain stracture level. This development was based on the knowledge that when blended with rubber, the anti-rubber performance (combination of high abrasion resistance and low heat build-up) can be effectively improved.

[Means to solve the problem]

That is, the carbon black for tire tread rubber provided by the present invention has a nitrogen adsorption specific surface area (NtSA
) Belongs to the bird type region with a force of 60 to 160 rrr/g and a DBP oil absorption of 90 to 150 m/100 g.
and the aggregate void volume Vp (at/g) is [0.0097
It is characterized by having selective characteristics that are greater than or equal to the value calculated by the formula 6 x DBP oil absorption - 0,03583.

Among the characteristics of carbon black, the nitrogen adsorption specific surface area (NSA) is in the particle range of 60 to 160 bo/g and the DBP oil absorption is in the range of 90 to 150 m/100 g. This is a prerequisite for imparting a high degree of abrasion resistance to compounded rubber. This nitrogen adsorption specific surface area (N.

SA) is less than 60rrf/g and DBP oil absorption is 9
If it exceeds ゜jd/100g, it will not be possible to provide high wear resistance that can be used as a tire tread.

In addition, if the nitrogen adsorption specific surface area (N less SA) exceeds 160 po/g, the dispersion into the rubber component will deteriorate, inhibiting the improvement of wear resistance, and at the same time causing an increase in heat generation. D
If the BP oil absorption exceeds 150af/100g, it is not preferable because the ice skid performance will deteriorate.

[0.00976X D B P oil absorption - 0,0358
) The aggregate void volume Vp (ml/g
) is a characteristic of the carbon black constituting the present invention, which exhibits a unique aggregate structure with highly developed struts, and is characterized by greater anisotropy than conventional carbon blacks of the same type. Can be attached. When the aggregate void volume Vp (m/g) is greater than or equal to the value calculated by the above formula, excellent wear resistance can be achieved while maintaining the same low heat build-up as the conventional carbon black formulation. It becomes possible to grant.

Each characteristic value of carbon black applied to the present invention is a value obtained by the following measuring method.

(1) Nitrogen adsorption specific surface area (N2SA) ASTM D 3037-78 “5 standard
Meth.

ds of Testing Carbon
Black 5surface Area by
Nitrogen Adsorptlon″Meth
According to ed B.

Nitrogen adsorption specific surface area (N
Wealth SA) is 80.3 bo/g.

(2) DBP oil absorption JIS K6221 (1975) rTesting method for carbon black for rubber” 6.1.2 The value obtained by oil absorption method A.

(3) Aggregate pore diameter IVp (af/g) Measure the aggregate pore diameter by injecting mercury into the carbon black sample using a mercury porosimeter, and obtain the aggregate pore diameter from 0.006 to 7.2μ using the following formula. Let the cumulative volume of the pore diameters be the aggregate pore volume Vp.

However, in the above formula, Xl is the indicated value at 25psi (P
F), X* is the end point indication value (PF), and CF is a constant determined by the cell. Note that the end point of X2 differs depending on the sample, but in the case of this measurement, when mercury is injected from the starting point of 25 psi, the indicated value decreases as the pressure increases, but when the pressure is further increased, the indicated value decreases. The end point is the value just before the pressure point where the indicated value shows a sudden increase.

Carbon black with these characteristics is produced by installing two generation sections each consisting of a combustion chamber equipped with a combustion burner and a feedstock oil injection nozzle at the head, and a thermal decomposition conduit connected to the combustion chamber, and a thermal decomposition section in the regeneration section. A method using an oil furnace with a Y-shaped structure in which conduits are convergently connected to a cylindrical main reaction zone, and carbon black intermediate gas streams generated in separate series are simultaneously introduced at high speed into the main reaction zone and collided with each other. Publication No. 62-10581).

At this time, the aggregate pore volume Vp can be adjusted by controlling the generation conditions of each series and the nitrogen adsorption specific surface area (N2S
A) and the DBP oil absorption amount are adjusted by controlling the combustion conditions in the furnace, the residence time of the produced carbon black flow in the furnace, etc.

The above-mentioned carbon black is blended into elastomers such as natural rubber, styrene-butadiene rubber, polybutadiene rubber, isoprene rubber, butyl rubber, and various synthetic rubbers and mixed rubbers that can be reinforced with other common carbon blacks, according to a conventional method. The blending ratio of carbon black is 1 rubber component
Rubber for tire treads is prepared by adding and kneading the necessary components such as vulcanizing agents, vulcanization accelerators, anti-aging agents, vulcanization aids, softeners, and plasticizers. Obtain a composition.

[For production]

Carbon black, which has a large aggregate void volume Vp, essentially has an aggregate structure with developed struts, and has the function of improving reinforcing properties when blended into rubber. 00976
When the characteristic requirements of the X D B P oil absorption amount - 0,0358) value or more are satisfied, the anisotropy of carbon black is significantly developed, and this action significantly improves the abrasion resistance of the rubber component. The prerequisite characteristics for this function are a nitrogen adsorption specific surface area (NO5A) of 60 to 160 bo/g and a DBP oil absorption of 9.
Working synergistically with the requirement of 0 to 150 d/100 g, the result is achieved that simultaneously imparts relatively low heat build-up and high abrasion resistance to the rubber component.

〔Example〕

Examples of the present invention will be described below in comparison with comparative examples.

(1) A combustion chamber (with an inner diameter of 400 mm
2 series of generation parts with 800 mm in length and 200 mm in conical part) and pyrolysis conduit (inner diameter 60 mm and 500 mm in length) are installed in the rear wide diameter section with an inner diameter of 200 mm and a length of 200 mm. Y is convergently connected at an intersection angle of 60° to the front side of the main reaction zone, which has a front narrow diameter section with an inner diameter of 90-1 and a length of 700 mm.
An oil furnace with a letter-shaped structure was installed. In the narrow diameter portion, a ring member with an aperture ratio of 0.65 was interposed 50 degrees downstream from the intersection.

Specific gravity (15/4°C) 1.0703, viscosity (
Engler-140/20℃) 2.10 Benzene insoluble content 0.03%, correlation coefficient (BMCI') 140,
An aromatic hydrocarbon oil with an initial boiling point of 103°C and a fuel oil with a specific gravity (154°C) of 0.903 and a viscosity (
CS750°C) 16. L charcoal bone 5.4%, sulfur content 1
．． 8% hydrocarbon oil with a flash point of 96°C was used.

Using the above reactor, raw material oil, and fuel oil, and applying the generation conditions shown in Table I, carbon black (3 types 1 [) having the characteristic range used in the present invention was manufactured. Nitrogen adsorption specific surface area (N2SA) of each carbon black
), DBP oil absorption, pore volume Vp and [0.
00976x D B P T & oil amount - 0,0358)
The relational expression values are shown in Table ■.

In addition, RunNa4 to 7 shown as comparative examples in Table 3
These are hard carbon blacks having a nitrogen adsorption specific surface area (NO5A) of 60 rrr/g or more manufactured by the conventional technique, and the aggregate pore volume Vp is outside the requirements of the present invention.

(3) Rubber compounding Next, the various carbon blacks listed in Table 1 were compounded with natural rubber at the compounding ratios shown in Table 2.

Table ■ Various rubber properties were measured for a rubber composition obtained by vulcanizing the formulation in Table ■ at a temperature of 145° C. for 40 minutes. The results are shown in Table 2 in correspondence with the blended carbon black Rur+Nn in Table 2.

The method and conditions for measuring the rubber properties were as follows.

(1) - Wear amount Measured using a Lambourn abrasion tester (II mechanical slip mechanism) under the following conditions.

Test piece: Thickness lO■, outer diameter 44mm Emery wheel: GC type, particle size 80, hard & H added carbon random powder: particle size 8o#, addition amount approx. 9g/min Relative slip ratio between emery wheel surface and test piece: 24 %
, 60% Test piece rotation speed: 535 rpm Test blue mold: 4 kg (2) tan δ Visco [1lastic Spectromet
er (manufactured by Harumoto Seisakusho) under the following conditions.

Test piece: Thickness: 2 mm, length: 30 mm, width: 5 mm Temperature: room temperature Frequency: 50 Hz Dynamic strain rate: ±1% (3) All other tests were conducted in accordance with JIS K6301r General Rubber Physical Test Method.

From the results in Table 2, it can be seen that the examples of the present invention maintain wear resistance per constant loss coefficient (tan δ) while maintaining the loss coefficient (tan δ), which is an index of heat generation, at the same level as the conventional comparative example of the same grade. It turns out that there is a significant improvement.

〔Effect of the invention〕

As described above, the carbon black according to the present invention has a highly anisotropic aggregate structure with highly developed stratch, and has high wear resistance and relatively low heat generation compared to compounded rubber. It is possible to impart both gender and gender at the same time. Therefore, it is useful to be blended into tread rubber for large tires such as trucks and buses used in harsh driving environments and to fully satisfy the required performance.

Patent applicant: Tokai Carbon Co., Ltd.

Claims (1)

[Claims] 1. Nitrogen adsorption specific surface area (N_2SA) is 60 to 160 m
^2/g, DBP oil absorption 90-150ml/100g
belongs to the Bird system region, and the aggregate pore volume Vp (ml
/g) is [0.00976 x DBP oil absorption - 0.035
8] Carbon black for tire tread rubber having selective properties greater than or equal to the value calculated by the formula.