JPH07752B2 - Carbon black for compounding functional parts rubber - Google Patents

Description

TECHNICAL FIELD The present invention relates to carbon black which is blended with a rubber member for functional parts such as a tire carcass or a vibration-proof rubber to give a high degree of reinforcement and low heat buildup.

[Conventional technology]

There are various varieties of carbon black for rubber reinforcement depending on the characteristics of the rubber, and these varieties characteristics are the main factors that determine the various performances of the composition compounded in the rubber. For this reason, when compounding rubber, a means for selecting and using carbon black having a variety of characteristics suitable for the intended use of the member is commonly used.

For example, for a rubber member for functional parts such as tire carcass or anti-vibration rubber that requires low heat generation, it is effective to use carbon black having a large particle size and a small specific surface area or a carbon black having a low structure. It is said that.

However, when carbon black having such a large particle size and a small specific surface area is used, there is a tendency to decrease the reinforcing property of the compounded rubber composition.

Therefore, if it is possible to impart a high degree of reinforcement to the compounded rubber composition while using carbon black having a large particle size and a small specific surface area, it is ideal as a rubber member for functional parts such as tire carcass and anti-vibration rubber. It will be

The Applicant has tried to make the above anti-rubber performance compatible from the viewpoint of the characteristics of carbon black, and as a result,
Carbon black for tire carcass in which the true specific gravity value is made relatively small and the aggregate Stokes mode diameter (st) is kept lower than the values corresponding to the N ₂ SA specific surface area and DBP oil absorption (JP-A-62-192468). Gazette), carbon black (Japanese Patent Application No. 62-157518) having a wide range of aggregate distribution at the same level of specific surface area and structure.

[Problems to be Solved by the Invention]

However, in the carbon black according to the above prior art, the nitrogen adsorption specific surface area (N ₂
The lower limit of (SA) is set to 60 m ² / g and 65 m ² / g, which is a prerequisite, which causes a problem of low heat generation and production restrictions.

The present invention provides a carbon black for compounding a functional component rubber capable of maintaining a low heat generation property and a high degree of reinforcing performance even if the lower limit of the nitrogen adsorption specific surface area (N ₂ SA) is reduced to about 50 m ² / g. Is.

[Means for Solving the Problems]

That is, the carbon black for compounding a functional component rubber according to the present invention has a CTAB in the range of 50 to 75 m ² / g and a DBP in the range of 105 ml / 100 g or more, and the selective characteristics of the following formulas (1) and (2). It is characterized by including.

However, in the above formula, CTAB is CTAB specific surface area (m ² / g), DB
P is DBP oil absorption (ml / 100g), N ₂ SA is nitrogen adsorption specific surface area (m
² / g), IA is the iodine adsorption amount (mg / g), (△ Dst / st) is the aggregate distribution index, of which △ Dst is the maximum frequency of Stokes in the aggregate Stokes equivalent diameter distribution by the centrifugal sedimentation method. Equivalent diameter (nm), st is the maximum frequency in the distribution
Difference in Stokes equivalent diameter of two points, large and small, that can obtain 50% frequency
Tint shall mean the relative coloring power (%).

For each of the above-mentioned characteristics of carbon black, the value obtained by the following measuring method is used.

(1) CTAB ASTM D3765-80 “Standard Test Method for Carbon B
lack-CTAB (CETYLTRIMETHYL AMMONIUM BROMIDE) Surfac
e Area ".

(2) DBP oil absorption amount JIS K6221 (1975) “Testing method for carbon black for rubber”, 6.1.2, Oil absorption amount A method.

(3) Nitrogen adsorption specific surface area (N ₂ SA) ASTM D3037-86 “Standard Test Method for Carbon B
lack-Surface Area by Nitrogen Adsorption "Method
According to B.

(4) IA JIS K6221-82 "Testing method for carbon black for rubber" 6 ・
According to Section 1.1.

(5) st, △ Dst Dry carbon black sample containing a small amount of surfactant 20
Carbon black concentration by mixing with 50% ethanol aqueous solution
Make a dispersion liquid of mg /, and disperse it sufficiently by ultrasonic wave to make a sample. Set the disk centrifuge (Joyes Lobel, UK) at a rotation speed of 8000 rpm, add 10 ml of spin solution (2% glycerin aqueous solution), and then add 1 m.
Inject l of buffer solution (aqueous ethanol solution). Then, 0.5 ml of the sample is added with a syringe to start centrifugal sedimentation, and at the same time, the recorder is operated to optically generate a distribution curve of the aggregate Stokes equivalent diameter. The Stokes 'equivalent diameter of the maximum frequency in the obtained distribution curve is st (nm), and the difference between the Stokes' equivalent diameters of two large and small points at which a frequency of 50% of the maximum frequency is obtained is ΔDst (nm). ASTM D according to this measurement method
-24 Standard Reference Black C-3 N-234
st is 80 nm and ΔDst is 60 nm.

(6) Tint JIS K6221-82 "Testing method for carbon black for rubber" 6
IRB # 3 is used for the comparison sample using the items 1 and 3.

Among the above characteristics of carbon black, CTAB50-75m ²
/ g, DBP 105ml / 100g or more area is a prerequisite for giving low heat buildup and high reinforcement to compounded rubber.
Is less than 50 m ² / g and DBP is less than 105 ml / 100 g, it is not possible to provide the reinforcing performance required for functional component rubber,
Further, when CTAB exceeds 75 m ² / g, the exothermic property is remarkably increased.

The requirement of the N ₂ SA / IA ratio shown in the formula (1) is related to the surface activity of carbon black. If this ratio is not less than 1.10, the property of high surface activity required for low heat generation can be obtained. Can't get

The selection characteristic of the aggregate distribution index (ΔDst / st) according to the equation (3) is a parameter that captures the relationship between the aggregate distribution and the specific surface area and the coloring power, and is (CTAB) × (Tin
It is characterized by the fact that the value of the aggregate distribution index (ΔDst / st) corresponding to t) is lower than that of the conventional carbon black. Then, when the requirement of the expression (2) is satisfied, the tensile product of the compounded rubber is improved, and at the same time, the resistance to crack growth is effectively improved.

Carbon black having the above characteristics, a combustion chamber having a combustion burner and a feedstock oil injection nozzle inserted in the furnace head in the connecting direction air supply port and in the furnace axial direction, and a plurality of stages of narrow diameters connected thereto, It can be manufactured by using an oil furnace having a structure having a wide-diameter reaction chamber and controlling various conditions such as a reaction temperature for reaction, a reaction time, a combustion gas flow rate, and a reaction residence time.

Carbon black of the present invention, according to a conventional method, natural rubber,
It is blended with elastomers such as styrene-butadiene rubber, polybutadiene, isoprene rubber, butyl rubber, various synthetic rubbers that can be reinforced with commonly used carbon black, and mixed rubbers. The compounding ratio of carbon black is the rubber component
25 to 150 parts by weight with respect to 100 parts by weight, and kneaded with necessary components such as a vulcanizing agent, a vulcanization accelerator, an antiaging agent, a vulcanization aid, a softening agent, and a plasticizer, and rubber for functional parts. Obtain the composition.

[Work]

The carbon black of the present invention is imparted with a property of high surface activity that brings about low heat generation to the compounded rubber by satisfying the requirement of the formula (1), and also has a tensile product and a tensile product by satisfying the requirement of the formula (2). Aggregate properties are provided that increase resistance to crack growth. The action of these selective properties acts synergistically with the suppression of heat buildup and the reinforcement maintaining function in the range of CTAB and DBP, which are prerequisites, and the N ₂ SA specific surface area is low even at the level of 50 m ² / g. The effect of simultaneously providing heat generation property and relatively high reinforcing property is exhibited.

〔Example〕

 Hereinafter, examples of the present invention will be described in comparison with comparative examples.

Examples 1 to 3 and Comparative Examples 1 to 4 A combustion chamber (diameter 400 mm, length 500 mm) having a tangential air supply port, a combustion burner inserted in the furnace axial direction, and a raw oil injection nozzle was installed in the furnace head. And a narrow-diameter reaction chamber (first stage: diameter 170 mm, length 500 mm, second stage: diameter 150 mm, length 1000 mm) that is coaxially connected to the combustion chamber, and a wide-diameter reaction chamber (diameter 500 mm) that follows. Carbon black was produced by changing the generation conditions using the above-mentioned oil furnace.

Specific gravity (15/4 ℃) 1.073, viscosity (Engla 40/20 ℃) 2.10, toluene insoluble content 0.03%, correlation coefficient (B
MCI) 140, aromatic hydrocarbon oil with an initial boiling point of 103 ° C, and specific gravity (15/4 ° C) 0.903 for fuel oil, viscosity (CST50 ° C) 16.
1. Hydrocarbon oil with residual coal content of 5.4%, sulfur content of 1.8% and flash point of 96 ℃ was used.

The generation conditions are shown in Table I, and the characteristics of the carbon black of the present invention obtained in Table II are shown in comparison with Example No., respectively. It should be noted that Comparative Examples 1 to 4 in Table II show conventional types of carbon black that deviate from the characteristic requirements of the present invention.

Next, these carbon black samples were blended with natural rubber in the blending ratio shown in Table III.

Various rubber characteristics of the rubber composition obtained by vulcanizing the compound of Table III at a temperature of 145 ° C. were measured, and the result is shown in Table IV.

The loss coefficient (tan δ) among various rubber characteristics was measured under the following conditions using a Visco-Elastic Tech Spectrometer (manufactured by Iwamoto Seisakusho).

Test piece: length 35 mm, width 5 mm, thickness 2 mm Frequency: 50 Hz Temperature: 25 ° C Dynamic strain rate ε: ± 1.2% All other rubber properties were measured by JIS K6301 "General rubber test method".

From the results in Table IV, the rubber compounding properties according to the examples of the present invention are carbon black compounding examples of conventional properties (comparative examples) in which the loss factor (tan δ) as an index of exothermicity is at the same N ₂ SA level.
It can be seen that the tensile strength, tensile product (product of tensile strength and elongation), and flexural crack growth are improved. In particular, it is a remarkable effect that Example 1 having N ₂ SA of 53 m ² / g has both good low heat generation property and reinforcing property.

〔The invention's effect〕

As described above, the carbon black provided by the present invention can have both a low exothermic property and a high degree of reinforcing property in the particle characteristics with N ₂ SA50m ² / g being the lower limit, which has been conventionally difficult. It is possible to maintain other rubber performance at a high level. Therefore, the performance required for compounding functional component rubber such as tire carcass or anti-vibration rubber is satisfied.

Claims (1)

[Claims] 1. A carbon black for compounding a functional component rubber, which has a CTAB in the range of 50 to 75 m ² / g and a DBP in the range of 105 ml / 100 g or more and has the selective characteristics of the following formulas (1) and (2). However, in the above formula, CTAB is CTAB specific surface area (m ² / g), DB
P is DBP oil absorption (ml / 100g), N ₂ SA is nitrogen adsorption specific surface area (m
² / g), IA is the iodine adsorption amount (mg / g), (△ Dst / st) is the aggregate distribution index, of which △ Dst is the maximum frequency of Stokes in the aggregate Stokes equivalent diameter distribution by the centrifugal sedimentation method. Equivalent diameter (nm), st is the maximum frequency in the distribution
Difference in Stokes equivalent diameter of two points, large and small, that can obtain 50% frequency
Tint shall mean the relative coloring power (%).