JPH06867B2 - Highly reinforced farnes car bomb rack for rubber - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a novel carbon black produced by an oil furnace method, and more specifically, it imparts a high degree of abrasion resistance to a compounded rubber composition, The present invention relates to a SAF grade carbon black which gives a rubber composition having improved characteristics and processing characteristics.

(b) Conventional Technology and Problems SAF (Super Abrasion Furnace) carbon black imparts a high degree of wear resistance when compounded with rubber and is mainly used for tire treads.

In recent years, the radialization of tires has progressed, and along with this, there has been a demand for a rubber composition for a tread having improved wear resistance. Especially for heavy-duty truck and bus tires, abrasion resistance on the tread surface is desired, and ISAF (Intermediate SA
There is a tendency to shift from F ... quasi-super abrasion resistance grade carbon black to SAF grade carbon black.

However, a carbon black having a high surface area such as a SAF class carbon black has a small particle size, which deteriorates the dispersibility in rubber, and generally the wear resistance improves as the particle size decreases. There is a problem that the effect is not expressed.

To solve this problem, non-uniform mixing of carbon black in a polymer blend, two-stage mixing, use of a master batch, etc. have been proposed, but it is difficult to say that they have been completely solved.

Further, in a high surface area carbon black compounded rubber composition, there is a tendency that heat generation due to hysteresis loss increases.

(c) Object of the invention The object of the present invention is to eliminate the above-mentioned drawbacks and to impart even higher wear resistance than a normal SAF-class carbon black compounded rubber composition, and also to have exothermic properties and impact resilience. Provided is a high reinforcing furnaceness carbon black that provides an improved rubber composition.

(d) Structure of the invention The basic characteristics of carbon black are surface area (particle diameter) and particle connection (structure), and wear resistance increases as surface area increases (particle diameter decreases).
When the reinforcement is improved and the structure is increased, the wear resistance is also improved (especially when the severity is high). However, when the wear resistance and the reinforcement are improved,
It is also known that hysteresis characteristics such as reduction of impact resilience and increase of heat generation are reduced.

In a rubber composition, attempts have been made to solve this contradictory matter with a carbon black having the largest compounding amount, and one of the present inventors has found that the size distribution index of the aggregate, which is the minimum dispersion unit of the carbon black, solves this. And found that it was a means to
-208369 bulletin, applicant: Asahi Carbon Co., Ltd. However, in the present invention, the surface area range is 105 to 1 in terms of iodine adsorption amount.
It is limited to 30 mg / g, and because the aggregate size distribution index s is on the wider side, in the SAF class carbon black with N ₂ SA exceeding 130 m ² / g, a normal SAF class carbon compound rubber composition is used. It has a drawback that it is difficult to impart more abrasion resistance.

The present invention provides, in addition to the aggregate size distribution, the ratio (D ₄ ) of the weight average diameter (D ₄ ) to the arithmetic average diameter (D ₁ ) calculated from the particle diameter of carbon black photographed directly by electron microscopy.
/ D ₁ ) is in the specific range on the smaller side, and more preferably, if the difference between the value of D _{1 and} the value calculated from the formula is small in addition to the above characteristics, the aggregate size distribution It has been completed by finding that the characteristics of impact resilience and heat generation are not deteriorated even if the index is moved to the smaller side, and that abrasion resistance and hysteresis are compatible even if the surface area range is increased.

That, 160 m less than ² / g over the N ₂ SA is 130m ² / g, DBPA
Is 1.10 ml / g to 1.50 ml / g and Tint is 121 or more in the furnace carbon black, and the aggregate size distribution index s is 0.11 to 0.15, and the arithmetic mean diameter D calculated from the particle diameter by the electron microscopy method. the ratio of the weight average D ₄ for _1, in which D ₄ / D ₁ to provide a rubber high reinforcing furnace carbon black in the range of 1.20 to 1.45.

In addition to satisfying each of the above characteristics, the arithmetic mean value
By making the standard deviation of D ₁ 4-6.5 nm and adding the characteristic that the difference between D ₁ and Dc calculated by the following equation (1) is 2 or less, the effect of the present invention is more remarkably expressed. be able to.

If the N ₂ SA is less than 130m ² / g are no longer able to maintain the wear resistance possessed by ordinary SAF grade carbon, 160 m conversely ² /
Since it is difficult to be controlled within the scope of the present invention an aggregate or particle size to improve the hysteresis characteristics when exceeding g, should be limited to the range of less than 160 m ² / g exceed 130m ² / g There is.

When DBPA is less than 1.10 ml / g, there is a problem in terms of abrasion resistance and dispersibility, and when it is more than 1.50 ml / g, the processability of the rubber composition is reduced. Is 1.10
It should be in the range of ml / g to 1.50 ml / g.

If Tint is less than 121, the wear resistance of the SAF carbon black cannot be maintained, so Tint needs to be 121 or more.

The aggregate size distribution index (s) is a measure of the distribution width of a relatively large aggregate size, as will be described later, but if it exceeds 0.15, it should be better than the wear resistance of ordinary SAF carbon black. Is not preferable, and when it is less than 0.11, it is not desirable because the impact resilience is lowered and the hysteresis characteristics such as increase in heat generation are lowered. Therefore, the aggregate size distribution index s is limited to the range of 0.11 to 0.15.

Furthermore, the ratio of the weight average diameter D ₄ to the arithmetic average diameter D ₁ , D ₄
When / D ₁ exceeds 1.45, the wear resistance tends to decrease, and when it is less than 1.20, the hysteresis characteristic decreases, so it is necessary to set the range to 1.20 to 1.45.

The ratio of D ₄ for D _1, D ₄ / D ₁ indicates that the number of particles having a diameter larger than D ₁ is small, there are no large particles out.

More preferably, the standard deviation of D ₁ is in the range of 4.0 to 6.5 nm and the particle size distribution is sharp.

These requirements on D ₁ tend to be larger than those of ordinary SAF class blacks, and since the distribution is sharp, it is considered that the effect that the hysteresis characteristics can be improved while improving the wear resistance can be expressed. Be done.

Further, the carbon black having N ₂ SA, DBPA and Tint values specified in the present invention is in good agreement with Dc calculated by the above formula (1), and also in the carbon black of the present invention (Dc
-D ₁₎ is 2 or less, but is close to the calculated values, the aforementioned D ₄
There is a difference in the value of / D _{1 from} the conventional carbon black. A carbon black whose measured value exceeds 2 than the value calculated by the equation (1), that is, (Dc-D ₁ ) exceeds 2, tends to be deteriorated in impact resilience and heat generation characteristics, which is not desirable.

The carbon black of the present invention has a feature that D ₁ is on the large side, and further desirable requirements (Dc-D ₁ ) is small, and its distribution is sharp, so that the impact resilience while maintaining the reinforcing property, It is assumed that the heat generation characteristics are improved.

Each characteristic of the carbon black according to the present invention is measured as follows.

DBP oil absorption (DBPA): According to JIS K 6221-1982 A method.

Nitrogen adsorption specific surface area (N ₂ SA): According to ASTM D 3037-84 B method.

Coloring power (Tint): According to JIS K 6221-1982 A method.

Carbon black aggregate size (Carbon
Black Aggregate Size Analysis Method Equipment Used Disk Centrifuge Equipment (Joyce, UK)
(Loebl Co., Ltd.) Measurement method 0.05 to 0.1% of carbon black is added to a 30% aqueous methanol solution to which a small amount of a surfactant is added, and ultrasonic treatment is performed to completely disperse the carbon black. The rotation speed of the rotating disk with 15 to 20 ml of distilled water settling solution (spin solution) is 8000.
Set to rpm and add 0.02-0.03 ml of the above dispersion. At the same time as the dispersion was added, the recorder was activated to optically measure the amount of carbon black aggregate passing through a fixed point near the outer circumference of the rotating disk by sedimentation and record that amount as a histogram against time. To do.

Settling time can be calculated by the following two equations (General type of Stokes equation)
Convert to Stokes equivalent diameter to obtain a histogram of the Stokes equivalent diameter of the carbon black aggregate and its frequency.

In the equation (2), d is the Stokes equivalent diameter of the carbon black aggregate passing through the optical measuring point of the rotating disk at the time t after the start of sedimentation.

The constant K is the difference in spin liquid amount, viscosity, and density of carbon black at the time of measurement (true density of carbon black is 1.86 g /
ml)), and determined by the number of rotations. For example, when 17.5 ml of distilled water is used as the spin liquid and the measurement temperature is 20 ° C. and the disk rotation speed is 8000 rpm, the K value is 280.5, d is expressed in nm, and t is expressed in minutes.

Definition of s Stokes of the aggregate obtained by the above measurement operation
In the histogram of equivalent diameters, the Stokes equivalent diameter that gives the highest frequency (the maximum absorbance in actual measurement) is called Dst, and is a measure of the average size of the carbon black aggregate.

Also, in the histogram, 1/2 of the frequency indicated by Dst
And the Stokes equivalent diameter that is greater than Dst.
When D ^L ₅₀ ▼, the aggregate size distribution index is
It is defined by the following equation (3).

S = 084932 × log (▲ D ^L ₅₀ ▼ / Ds +) (3) This s value is a measure of the distribution width of a relatively large aggregate size.

Definition of D ₁ and D ₄ by electron microscopy Add 0.2 mg of carbon black to 1 ml of chloroform,
Disperse in ultrasonic cleaner for 5 minutes. This dispersion sample was fixed on a carbon support film and directly magnified by 20,000 with an electron microscope.
2,000 times, the final magnification is 150,000 times, the diameter of 2000 or more carbon black particles is randomly measured from the obtained photograph, and D ₁ and D ₄ are calculated from the histogram created by dividing into 48 categories. .

Assuming that the diameter of the i-th histogram is di and the number is ni, the arithmetic mean diameter D ₁ and the weight mean diameter D ₄ are
It is calculated by equations (4) and (5).

Calculation of D ₁ by Calculation The calculation D ₁ (Dc) used in the present invention is calculated by the above equation (1).

This equation (1) is written in Rubber Age, November 1973 issue, page 29 to page A.
shland Chemicals, Carbon Blackboard column 32 NLS
It was published by mith and was obtained from the regression equation of carbon black characteristics and D ₁ by electron microscopy.

The production examples of the carbon black of the present invention are shown below.

Production Example A carbon black of the present invention was produced using the apparatus shown in FIGS. 1, 2 and 3.

Cylindrical combustion gas filling chamber 2 (inner diameter 400mmφ, length 280m
m), two first air inlets 7 and 7 ′ (inner diameter 80 mmφ) having a central axis at a tangential position provided in the first half of the combustion gas filling chamber 2, and the first inlet. Are independent six radial second natural gas inlets 8, 8 ',
9,9 ', 10,10' (inner diameter 20 mmφ), a bench lily portion 3 having a narrowest inner diameter 80 mmφ and a length 150 mmφ connected to the combustion gas filling chamber, and 50 mm and 150 mm downstream from the outlet end of the bench lily portion 3. And four parallel and tangential directions each passing through the upper and lower ends of the same cross section provided so as to be introduced in the forward direction (tangent) or the reverse direction (reverse tangent) with respect to the turning direction of the first introduction port. Sets of third air and / or natural gas inlets 12, 12 ', 12 ", 1 with
2 ′ ″ and 13, 13 ′, 13 ″, 13 ″ ′ (inner diameter 30mm
φ) is installed in the reaction chamber 4, and a plurality of cooling water injection spray devices a to g are installed in the space on the downstream side of the third introduction port for continuing reaction and cooling chamber 5 (inner diameter 120 mmφ, length 3000 mm). )
And a flue 6 connected to the rear end of the cooling chamber for continuing the reaction, the carbon black reactor 1 entirely covered with a refractory is used, and air from the first and second inlets and The specific surface area, structure, aggregate size distribution index (s), D ₄ / D ₁ and D can be adjusted by adjusting the natural gas supply conditions, the gas body supply conditions from the third inlet, and the swirling direction. SAF class furnace carbon blacks with different standard deviations of ₁ were manufactured.

In the narrowest part of the bench lily, pass through the same space 2
The individual feedstock inlets 11 and 11 'were provided, and the feedstock injection device was installed at this inlet to introduce the feedstock.

As the raw material hydrocarbon, one having the properties and composition shown in Table 1 was used.

Table 2 shows the production conditions and the physicochemical properties of the produced carbon black.

Ruu Nos. 1 to 6 and 9 in Table 2 are carbon blacks according to the present invention and satisfy all the requirements.

Ruu No. 7 is an example in which the ratio of D ₄ / D ₁ and the standard requirement of D ₁ , which is a desirable requirement, are deviated, and Ruu No. 8 is an example in which s is deviated to the larger side. Also, Ruu Nos. 1, 5 and 9 are another desirable requirement, calculation D ₁ and actual measurement.
This is an example in which the difference from D ₁ is large, and Ruu No. 10 is an example in which s deviates toward the smaller side.

Performance Evaluation Test In order to evaluate the performance of the carbon black shown in Table-2, the rubber composition was adjusted with the compounding ratio shown in Table-3,
It was subjected to various tests.

The performance of each rubber composition was measured and evaluated under the following rubber characteristic test conditions.

Rubber property test conditions Vulcanization condition of compound: 145 ° C, 30 minutes Abrasion resistance test: Measured with a Lambourn abrasion tester at a slip rate of 25%, and the abrasion resistance is calculated by the following formula.

Abrasion resistance index = (S / T) × 100 (%) where S: volume loss of IRBNO.5 test piece at 25% slip ratio.

T: Volume loss at 25% slip rate of the supplied test piece.

Anti-repulsion elasticity test: BS (British Standard) 903: Part A 8: 1963 A using resilience tester
Measure according to the method.

Other rubber properties: JIS K 6300-1974 and JIS
Measure according to K 6301-1975.

For the rubber properties of each carbon black, see Table-
It is summarized in Table 4.

(e) Effect From the results of Table-4 in which the carbon blacks of Examples and Comparative Examples having the colloidal properties shown in Table-2 are blended with natural rubber, the results of Table-4 show the effects of the carbon black of the present invention on abrasion resistance and impact resilience. Also, the characteristics of heat generation will be compared and described.

i) Wear resistance Ruu No. 4 and R, which are almost the same combination of N ₂ SA and DBPA
In uuNo.7, RuuNo.7 has a standard deviation of D ₄ / D ₁ and D ₁ (there is almost a positive correlation between these two characteristics), which is outside the requirement of the present invention. The wear resistance index is greatly reduced. Despite this, Ruu
The impact resilience and heat generation of No. 4 are almost the same as those of Ruu No. 7, and the effect of the present invention is clear.

In addition, comparing Ruu No.3 and Ruu No.8, they have almost the same colloidal. However, since Ruu No.8 deviates from the requirement to the side where s is large, the wear resistance (some ) There is a decline.

ii) Rebound resilience and heat generation Ruu No.10 is an example in which s deviates from the requirements of the present invention to the smaller side, and in terms of wear resistance, it is equivalent to Ruu No. 2 and No. 5 having a larger surface area than Ruu No. However, it is unsuitable because it has a larger value in heat generation than these values.

Ruu Nos. 1 and 9 are examples in which the measured D ₁ value is smaller than 2 by less than the calculated D ₁ (Dc), but Ruu No. 9 is R
Compared to uu No. 1, N ₂ SA is large and s is small, so there is some improvement in wear resistance, but there is a decrease in properties in impact resilience and heat generation, so (Dc-D ₁ ) is smaller. Is preferable, and more preferably 2 or less.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an apparatus suitable for manufacturing the carbon black of the present invention shown in FIG. 1. 2 is a cross-sectional explanatory view taken along the line AA of FIG. 1, and FIG. 3 is a cross-sectional explanatory view taken along the line BB of FIG. 1 ... Carbon black manufacturing device 2 ... Combustion gas filling chamber 3 ... Venturi section 4 ... Reaction chamber 5 ... Reaction continuation and cooling chamber 6 ... Flue 7, 7 '... Air inlet 8, 8', 9, 9 ', 10, 10 '... Fuel fluid inlet 11, 11' ... Raw oil inlet 12-12 '", 13-13"' ... Inlet a-g ... Cooling water press-in sprayer inlet

Claims (3)

[Claims] 1. A nitrogen adsorption specific surface area (N ₂ SA) 160 m ² / less g exceed 130m ² / g, DBP oil absorption (DBPA) is 1.10
In a furnace carbon black having a characteristic of 1.50 ml / g and a specific tinting strength (Tint) of 121 or more, the aggregate size distribution index (s) is 0.11 to 0.15, and the arithmetic calculated from the particle diameter by electron microscopy. A highly reinforced furnace carbon black for rubber having a ratio (D ₄ / D ₁ ) of the weight average diameter (D ₄ ) to the average diameter (D ₁ ) in the range of 1.20 to 1.45. 2. The highly reinforced furnace carbon black for rubber according to claim ₁ , wherein the standard deviation of D ₁ is 4 to 6.5 nm. Wherein the D ₁ and the following difference (Dc-D ₁₎ rubber for high reinforcing Sulfur Ness carbon black according paragraph 1 claims is 2 or less and calculated Dc in calculations.