JPS6042439A - Rubber composition - Google Patents

Abstract

PURPOSE:An automotive tire rubber composition excellent in reinforcing properties (tesnsile strength and modulus) and dynamic properties (low heat build-up and high resilience), prepared by compounding a rubber component with furnace carbon black having specified properties. CONSTITUTION:Use is made of furnace carbon black having the following properties: electron microscopic average particle diameter (dn) >=31mmu, iodine adsorption of 25-60mg/g, DBP absorption of 90-150ml/100g, Dst mode diameter (mmu) <= a value determined from the equation, and LAC340 (a measure of surface activity) >=120. Namely, 100pts.wt. rubber component (e.g., natural rubber, styrene/butadiene rubber, or polybutadiene rubber) is compound with 25- 250pts.wt. above carbon black. This rubber composition is excellent in reinforcing properties and dynamic properties and can be molded by using carbon black having an iodine adsorption of a wide tolerable range.

Description

[Detailed Description of the Invention] In recent years, rubber materials such as those used in automobile tires have been required to have a high level of reinforcing performance (tensile strength, modulus, etc.) and dynamic performance (low light/thermal resistance, high rebound resilience, etc.). There is an increasing demand for simultaneous provision of these properties, but since these two properties are essentially contradictory, it is difficult to satisfy this demand from the viewpoint of rubber components.

The applicant investigated the characteristics of Cargin black, which is the main compounding material for rubber compositions, and determined the average diameter (
an) 31 mμ or more, iodine adsorption amount 40 to 60 tq
/l, DBP oil absorption in the characteristic range of 90~150m17100f, Dl
lt-T--Diameter Cmp>(2,65((lN+0.
64 (DBP)-27, 56) A rubber composition that meets the above requirements by blending carbon black with selective properties that are less than the value obtained from the formula 25 to 250 parts by weight based on the rubber component. The item has already been patented in 1986-196.
No. 022 (hereinafter referred to as "prior application technology") was developed and provided. This prerequisite particle property is FEF or Sake MA.
It belongs to the F-class soft system area, and while it imparts suitable dynamic performance to compounded rubber, it is also in the characteristic range that causes a reduction in reinforcing property.In the prior art, this reduction in reinforcing property was The Dgt mode diameter of the black aggregate is (2,
65 (an) + 0.64 (DBP) - 27,56) or less, it was successfully compensated for effectively. However, the rubber composition of the prior art is
In addition to causing a slight regression in dynamic performance, it is necessary to limit the lower limit of the particle surface area to an iodine adsorption amount of 40 ny/l, which is a practical difficulty that limits the degree to which dynamic performance is imparted. was there.

The present invention improves the drawbacks of the prior art by maintaining the LAC340 value, which indicates surface activity, as a new carbon black characteristic factor, to a certain level or higher. That is, the present invention provides a rubber composition that has both reinforcing performance equivalent to that of the prior art and higher dynamic performance.
31fiμ or more, iodine adsorption amount 25~60~/f%DB
In furnace carbon black in the characteristic range of P oil absorption 90 to 15 (tffll/100f), the Dst mode diameter (mμ) is (2,65(an) + 0.64
(DBP) −27,56) Carbon black with selection/fishing properties that is less than the value calculated from the formula and has an LAC34Q measurement value of 120 or more relative to the rubber component.
It is characterized by being blended in a proportion of 250 parts by weight.

Among the characteristic items used in the present invention, the electron microscope average particle diameter (an), iodine adsorption amount, DBP oil absorption amount, and DIl
Each part of the lt mode diameter is determined by the following measurement method as in the prior art.

(1) Electron microscopy average particle diameter (an) carbon black sample was cleaned using an ultrasonic cleaner at a frequency of 28 KHz.
After dispersing in chloroform for 0 minutes, the dispersed sample is fixed on a carbon support membrane [Details are described, for example, in "Illustrated explanation of powder physical properties" (Powder Engineering Research Gold Line), page 68 (C) "Water surface membrane method" ].

This was photographed directly with an electron microscope at a magnification of 20,000x and a total magnification of 80,000~too, 000x, and 1. The arithmetic mean diameter (dn) is calculated from a histogram created by measuring the diameters of nine carbon black particles of OO or more and dividing them into 3 mμ increments.

(2) Iodine adsorption amount J Engineering S K6221 (1975) Test method for carbon blank for rubber J According to the method described in Section 6.1.1.

(3) According to DBP Oil Absorption Keiji Kogyo S K6221 (1975) r Test Method J of Carbon Black for Rubber Section 6.1.2, Oil Absorption A Method.

(4) Dst mode diameter J Engineering S K6221 (1975) 6.2.1 A carbon black specimen, which was precisely weighed and collected based on method B, was added to a 20% aqueous ethanol solution containing a small amount of surfactant (dispersion medium). Mix with carbon black concentration 100JIF/
A dispersion liquid of 1 is prepared and sufficiently dispersed using ultrasonic waves to prepare a sample. Disk centrifuge installation! (UK, To
yes LOeb1 company! R) at a rotation speed of 6.000 rpm, and 1.
After adding within the range of 0 to 20 ml, 1+nQ of buffer solution (ethanol aqueous solution) is injected. Next, a sample solution of 0.5-I and Orni is added using a syringe to start centrifugal sedimentation, and at the same time a recording needle is activated to optically separate and record aggregates to create a distribution curve. The Dot mode diameter is defined as the Stokes equivalent diameter (mμ) of the most frequent occurrence (maximum absorbance) in the aggregate distribution curve.

LAC34Q, a new characteristic element, is a scale that seems to be related to the surface activity of carbon black particles.
TM D3392-79 '5 standard Rec
om-mended Practice for Ca
rbon Black1! ! xtractables
-Light -absorption Charac
-Measure in accordance with teristics. That is, a predetermined amount of sample carbon black pellets was pulverized, dried, and shaken for 1 minute in 5ocrtt of dichlorobenzene, and then the carbon black was separated by p-percentage to obtain 34Qm of the solution.
Measure absorbance at μ wavelength.

Calculated from LAC44QAC44Q measurement values.

LAC340=AX to'/(axb) In the above formula, A is the solution absorbance at a wavelength of 540 mμ, b is the measurement cell optical path length (to), and d is the carbon black sample concentration (Kf/m').
).

LAC34 added to applied carbon black of the present invention
The selective property with a Q measurement value of 120 or more contributes to the KTj effect of increasing both reinforcement and dynamic performance of the compounded rubber due to its unique effect based on its high surface activity, and it eliminates the dynamic performance regression phenomenon in the prior art. It serves the function of sufficiently supplementing the reinforcement performance and maintaining the reinforcing performance at a high level. Therefore, it is possible to expand the lower limit of the prime quantity to 25 q/li, which is equivalent to G PF (N660) class carbon black, so that it becomes a prerequisite characteristic, and dynamic performance can be improved from this aspect as well.

Carbon black having the characteristic requirements of the present invention has a combustion chamber equipped with a tangential air supply port in the furnace head, a combustion burner inserted in the axial direction of the furnace, and a convergent nozzle with a raw oil injection nozzle on the downstream side. It is produced in an oil furnace having a structure in which the reaction zone is converged and connected in a relatively short narrow diameter section, and the reaction zone is formed into a tapered shape that gradually widens from the narrow diameter section. Raw material oil such as creosote oil or ethylene bottom oil is ejected into high-temperature combustion gas flowing at high speed through a narrow diameter portion through a raw material oil injection nozzle. At this time, by controlling conditions such as the supply ratio of the total amount of air supplied to the total amount of raw material oil and fuel oil, the combustion rate of fuel oil, the initial jetting speed of raw material oil, and the flow rate of combustion gas, the prerequisite electron microscope average Particle diameter (dn) 3'1 mμ or more, iodine number 25-60q
/f and DBP/oil absorption 90-150mff1/1
oor's rough physical properties are partially imparted by spraying a small amount of water onto this hill or one part of the expanding taper of the reaction zone, and setting the residence time of the produced gas to this position in the range of 30 to 50 milliseconds. [2.65 (an) +
0.64(DBP)-27,56] D6t less than the calculated value
Characteristics of mode diameter and LAC54Q measurement value of 120 or more are given.

The carbon black having this characteristic is blended into 11 components each of natural rubber, styrene-butadiene rubber, polybutadiene rubber, isopre/rubber, and butyl rubber nat by a conventional method. The blending ratio of carbon blank is 25 to 250 parts by weight, preferably 40 to 80 parts by weight, per 100 parts by weight of the rubber component.
It is added and kneaded together with necessary components such as commonly used vulcanizing agents, vulcanization accelerators, anti-aging agents, vulcanization aids, softeners, plasticizers, etc. in parts by weight. During compounding, the Mooney viscosity of the composition is always kept low, and kneading and extrusion processes such as cross-crossing, extrusion, and molding proceed extremely smoothly.

The rubber composition of the present invention thus obtained has both reinforcing performance and dynamic performance that are relatively superior to those of the prior art. Moreover, since the range of prime number loading can be expanded in the applicable carbon plan 2 compared to the prior art, there is an advantage that the target rubber applications can be expanded.

Hereinafter, the present invention will be explained based on examples.

Example: The combustion chamber (inner diameter 700mm, length 1000mm) in which the downstream outlet portion converges has an inner diameter of 1501111mm. It has a cylindrical shape lined with refractory bricks that is continuous with a tapered reaction zone (length 9000111) that gradually expands through short and long narrow diameter parts of 200U in length, and has a tangential air supply port in the furnace head. A wind box equipped with a wind box, a quench nozzle was installed in the downstream region of the reaction chamber, and a combustion burner and feedstock oil atomization injection nozzle were inserted from the furnace head along the furnace axis direction. Furthermore, a water spray nozzle was inserted and installed in one part of the reaction zone where the reaction area was widened and expanded. The raw material oil atomization injection nozzle was installed so that the tip portion was located at the entrance of the narrow diameter section, and the water spray nozzle was installed at a position 1100 mm downstream from the narrow diameter section outlet.

Carbon black was produced using the above reactor and applying the generation conditions shown in Table IIC.

Fuel oil has a specific gravity (15/4℃) of 0.903 and a viscosity (C
0T50℃)16.1. Remaining coal content 5.4%, sulfur content 1.8
%, a hydrocarbon with a flash point of 96°C was used, and the feedstock oil had a specific gravity (
1574℃) 1.0703, viscosity (Engler 140
A highly aromatic hydrocarbon oil having the following properties: QC)2, 1O, benzene insoluble content 0.03%, correlation coefficient (BMC Engineering) 140, and initial boiling point 103°C was used.

(Note) *Residence time of generated carbon black-containing gas to water cooling point.

** Residence time of the produced carbon black-containing gas to the reaction section water sg point.

*** Ratio of water cooling point to water volume (@.

The table shows the characteristics of each manufactured carbon black in comparison with the characteristics of commercially available GPF (H660) and FF1F (N550) class soft carbon blacks, and each type (conventional example) of engineered RBΦ5 standard carbon black. .

Among the production lots, Runs N114 to 6 did not meet the selective characteristic requirements of the present invention (comparative examples).

The various carbon black samples shown in Table H were blended with natural rubber components and synthetic rubber components at the blending ratios shown in Table 1.

Table 1 Various rubber properties were measured for a rubber composition obtained by vulcanizing the surface layer compound at a temperature of 145°C. Table 1 shows the results.
The results are shown in Table IVK in correspondence with the blended carbon black samples (Run%).

Among the rubber properties, the degree of heat generation was measured using a Guttrich flexometer according to ASTM D623-67A method.

For other rubber properties, all JlSK6301
Compliant with "General Rubber Test Method" K.

From the results in Table N, it can be seen that the rubber composition according to the present invention (Run I
V&lL1~3) is the conventional type PKF (N550)
The dynamic performance of the grade carbon black compound rubber (
High reinforcement performance (tensile strength, 300% modulus) that exceeds the same FIP compound rubber while having low heat build-up and high impact resilience)
It is permitted to show the following.

Among the targets, Run 1 has a remarkable improvement effect on dynamic performance.
I & 11 is FJC despite the fact that K has a low iodine amount of carbon black, which is a basic characteristic, at 29 capes/f.
It has reinforcing performance similar to F-compound rubber, which is a major feature that cannot be obtained with the prior art.

In contrast to the above-mentioned examples of the present invention, in all of the comparative examples, the selective characteristics (Dst mode diameter, LAcHo) of the applied carbon black are out of the requirements of the present invention, so that relatively no improvement in dynamic performance was obtained.

Patent applicant: Tokai Carbon Co., Ltd. Agent: Patent Attorney Masaya Takahata

Claims (1)

[Claims] Electron microscope average particle diameter (an) 51 mμ or more, iodine adsorption amount 25-60q/f% DBP oil absorption amount 9'0-15
In furnace carbon black in the characteristic range of 0mff1/100f, Det% - diameter (mp) is (
2,65 (dn) + 0.64 (DBP) - 27, u6]
A rubber composition comprising 25 to 250 parts by weight of carbon black with respect to a rubber component, which has a selective characteristic of having a LAC54Q measurement value of 120 or more, which is less than or equal to the value calculated from the formula.