JPS62192468A - Furnace black for tire carcass - Google Patents

Abstract

PURPOSE:To provide the titled furnace black which has excellent tensile strength and elongation, gives a rubber compsn. capable of inhibiting heat buildup, has specified selective characteristics and can reduce ply loosening, by thermally decomposing a raw hydrocarbon oil while controlling a reaction temp., a reaction time, etc. CONSTITUTION:A raw hydrocarbon oil is injected into a high-temperature turbulent gas stream of combustion gas formed by burning fuel oil and thermally decomposed while controlling a reaction temp., a reaction time, etc. At the same time, the decomposition products are subjected to complicated polycondensation reactions to obtain the titled furnace black which belongs to a hard region where a nitrogen adsorption surface area (N2SA) is not lower than 60m<2>/g and a DBP absorption is 60-90ml/100g, and has a true specific gravity of not higher than a value calculated from formula I and selective characteristics wherein the stokes' mode size of its agglomerate is not larger than a value calculated from formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a furnace black for a tire carcass having a novel characteristic that is blended with a rubber component to reduce blithe looseness as a rubber composition for a tire carcass ply. J There are various types of furnace blacks used for rubber reinforcement, depending on their characteristics, and they are usually classified based on characteristics such as average particle size, specific surface area, and stracture.The characteristics of these furnace black varieties are as follows: Since it is an important factor that determines various performances of the rubber composition to be blended, it is appropriately selected and used depending on the intended use.

For example, the tire carcass has the function of withstanding the load, impact, and air pressure that the tire receives.
High tensile strength is required and l5AF is generally used in this application field.
-LS (N-219) and HAF-LS (N-3'26)
Varieties such as:

In recent years, there has been a strong demand for high-speed durability for truck and bus tires, and as tire structures have become more radial, cords with high elastic modulus such as polyester and steel are being used for carcass cords. therefore,
Cracks in the rubber part of the carcass ply occur due to expansion and contraction between the cords during driving and shear strain in the cord direction when touching the ground.
Breakage is likely to occur, and a so-called ply loose phenomenon occurs. Generally, in order to reduce this ply looseness, it is important to prevent thermal aging of the rubber due to heat generated during running, and to reduce fatigue deterioration due to repeated strain during running.

"Problems to be Solved by the Invention" Furnace blacks with large particle diameters and small specific surface areas are generally used to impart low heat generation properties to rubber compositions, but these blacks have low reinforcing properties. Therefore, the breaking strength is impaired, and the carcass cord and the rubber may peel off, making it impossible to maintain durability.

The present invention eliminates these drawbacks and provides a furnace black for a tire carcass that has new characteristics that maintains high breaking strength and elongation as a rubber composition and provides low heat build-up.

"Means for solving the problem" That is, the present invention has a nitrogen adsorption specific surface area (N2SA) of 6
0m2/g or more, DBP oil absorption 60-90xQ/10
It belongs to the hard type area of 0g, and the true specific gravity value is {1.8379
0,0006x(NtSA)), and the Stokes mode diameter Dst of the aggregate is {
0.286X (DBP) - 0,621X (N2SA) +
This is a furnace black for a tire carcass, which has a structural feature of having a selective characteristic equal to or less than a value calculated from the formula I14.4).

The true specific gravity value of furnace black can be understood as a different characteristic element different from particle size and stracture.

Furnace black is produced through a thermal decomposition reaction by injecting raw hydrocarbon oil into a high-temperature turbulent air stream of combustion gas formed by burning fuel oil.The raw hydrocarbon oil undergoes a complex polycondensation reaction to become carbon black. Transform. In this production process, the true specific gravity value of furnace black can be considered as a parameter indicating the degree of formation of carbon microcrystalline structure inside each particle constituting the furnace black. For example, furnace black with a low true specific gravity value has a carbon It is thought that the formation of a microcrystalline structure is insufficient, more hydrocarbon properties remain, and the constituent particle surfaces are rich in chemically active radicals. Therefore, this true specific gravity value has a close relationship with the production reaction temperature, production reaction time, etc. in the production process of furnace black, and as a result, it has a correlation with the specific surface area or particle size of the furnace black. In the present invention, the true specific gravity value is {1.83
79-0,0006x (N, 5A)) By setting the value to be less than or equal to the value calculated from the formula, it becomes possible to provide a unique surface texture with high surface activity.

Next, the Stokes mode diameter Dst of the aggregate is a parameter that indicates the properties of the aggregate in which furnace black particles are firmly fused and bonded, and is a parameter that indicates the properties of the aggregate, such as the production reaction temperature and the degree of disturbance of combustion gas in the furnace black production process. Closely related to conditions. As a result, the Stokes mode diameter Dst of the aggregate is correlated with the stracture and specific surface area, and the inventors found that f15st is {0.28
6X (DBP) - 0,621X (N2SA) + 11
It was confirmed that when the value was lower than the value calculated from the formula 4.4), the reinforcing properties of the rubber composition were significantly improved. This is characterized by the relatively small size of the aggregates corresponding to the size of the strafture and specific surface area.

By specifying the true specific gravity value and the size of the aggregates of the furnace black as described above, the interfacial reaction with the rubber component is promoted, thereby reducing heat generation and improving reinforcing properties of the rubber composition.

For each characteristic value of the furnace black applied to the present invention, values determined by the following measurement method are used.

(1) Nitrogen adsorption specific surface area (N2SA) ASTM D3037-78 “Standard M
methods ofTesting Carbon B
1ack - S urrace Area byN
itrogen Adsorption”Method
According to B.

In addition, the value of lB#5 measured by this method is 80.311
It was ffi/9.

(2) True specific gravity: 650 ±
After performing a deaeration treatment at a temperature of 25° C. for 5 minutes, the measurement is performed in accordance with method B published in “Industrial Chemistry Magazine” Vol. 66, No. 12 (+963), page 1758.

That is, an appropriate amount of the degassed sample is weighed into a pycnometer, immersed in a small amount of benzene, and then degassed under reduced pressure of 2 to 5 yHg until no bubbles are observed.

Next, fill the vicinometer with benzene to 25±o
, kept in a constant temperature water bath for 30 minutes, and then weighed. The true specific gravity value is calculated by the following formula.

However, A is the mass of the pycnometer, C is the mass of the pycnometer+benzene, D is the mass of the pycnometer plus the carbon black sample, E is the mass of the pycnometer plus the carbon black sample plus benzene, and dt5 is the specific gravity of benzene.

The value of IRB #4 measured by this method was 1.7780.

(3) Stokes mode diameter of aggregate IDstJIS K
6221 (1975) Section 6.2.1 A carbon black sample, which was precisely weighed after drying according to method 8, was mixed with a 20% aqueous ethanol solution containing a small amount of surfactant to prepare a dispersion with a carbon blank concentration of 50 m9/Q. created and sufficiently dispersed using ultrasound.

Disk centrifugation device (UK J oyesL
(manufactured by oeb1) was set at a rotation speed of 800 rpm,
Spin liquid (2% glycerin aqueous solution) for 10-20 m (1
After adding within the range of 1i12 buffer solution (ethanol aqueous solution) is injected. Then sample solution 0.5-1,
OxQ is added with a syringe to start centrifugal sedimentation, and at the same time the recorder is activated to optically create an aggregate distribution curve.

DsL reads the Stokes equivalent diameter (Iμ) of the maximum frequency (maximum absorbance) in the aggregate distribution curve.

Furnace black having these characteristics can be produced by appropriately setting and controlling the thermal decomposition reaction conditions using a normal oil furnace reactor.

For example, production reaction temperature, production reaction time, combustion gas flow rate,
It can be obtained by adjusting various conditions such as atomization of the raw material oil. In particular, to reduce the true specific gravity value, shorten the carbonization time after the production reaction, and to reduce the Stokes mode diameter of the aggregates, apply conditions such as raising the production reaction temperature and increasing the combustion gas flow rate. It is effective to do so.

Furnace black having the above characteristics is mixed with natural rubber or various synthetic rubbers together with other rubber compounding agents by a conventional method.

In this case, it is desirable to mix and knead the furnace black in a proportion of 25 to 150 parts by weight, particularly 35 to 100 parts by weight, per 100 parts by weight of the rubber component.

"Function" The present invention maintains the true specific gravity value relatively lower than the value corresponding to the nitrogen adsorption specific surface area, thereby increasing the chemical activity of the furnace black surface and increasing the affinity with the rubber component. As a result, the heat generation of the rubber composition can be reduced.

Furthermore, reinforcing properties can be improved by setting the Stokes mode diameter of the aggregate to be relatively lower than the level corresponding to the structure and specific surface area.

"Example" A combustion chamber (
A narrow-diameter reaction chamber (diameter L50yx, length 100Q) coaxially connected to the combustion chamber (diameter 800cm, length 600xi)
Methods such as adding and introducing feedstock oil, fuel oil, air supply amount, and oxygen gas using a normal oil furnace consisting of a wide reaction chamber (diameter 400 ix) following a narrow-diameter reaction chamber and a narrow-diameter reaction chamber. Various furnace black samples were manufactured using this method.

Specific gravity (15/4°C) 1.073, viscosity (
Engler-40/20°C) 2.10, toluene insoluble content 0.03%, correlation coefficient (BMCI) I 40, and fuel oil with specific gravity (15/4°C) 0,
903, viscosity (CsL150°C) +6.1, remaining components 5.
A 4% hydrocarbon oil with a flash point of 96°C was used.

Carbon black was produced using the above oil furnace, raw material oil, and fuel oil, and the production conditions and characteristics of each carbon black sample are compared and shown in Table 1.

Next, these carbon black samples were blended with natural rubber in the proportions shown in Table 2.

Various rubber properties of the rubber composition obtained by vulcanizing this compound at a temperature of 145° C. for 40 minutes were measured, and the results are shown in Table 3 in comparison with sample No. of Table 1.

Table 3 Among the above rubber properties, tan δ is determined by Vtsco E 1astic Spectrom manufactured by Script Seisakusho.
Measurement was performed using eter under the following conditions.

Test piece: Thickness 2y, length 30IIIj11 medium 5RR
1 frequency + 501-tz Dynamic strain rate: ±1% All other rubber properties are based on JISK6301
rGeneral Rubber Test Method.

From the results in Table 3, sample N that satisfies the characteristic requirements of the present invention
o, 1 to 3 have better balance in overall characteristic values such as strength, elongation, and tan δ, which is an index of heat generation, compared to comparative and reference examples, so they are superior in terms of heat generation and breaking energy. It turns out that

"Effects of the Invention" As is clear from the above explanation, the rubber composition containing furnace black having the selective properties regulated by the present invention suppresses heat generation to a low level while maintaining high tensile strength and elongation. This can greatly contribute to reducing ply looseness when used in tire carcass plies.

Claims (1)

[Claims] 1.Nitrogen adsorption specific surface area (N_2SA) is 60m^2/g
As mentioned above, the DBP oil absorption belongs to the hard type area of 60 to 90ml/100g, and the true specific gravity value is {1.8379-0.00
06×(N_2SA)}, and the Stokes mode diameter Dst of the aggregate is {0.2
86×(DBP)−0.621×(N_2SA)+11
Furnace black for tire carcass having selective properties equal to or less than the value calculated from formula 4.4.