JPH0637594B2 - Carbon black with a wide distribution of aggregates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention supports reinforcement in a field requiring a high degree of reinforcement and low heat generation as a rubber member for functional parts such as tire carcass and anti-vibration rubber. However, it relates to carbon black that provides low heat buildup.

[Conventional technology]

There are various varieties of carbon black for rubber reinforcement depending on the properties of the rubber, and these varieties of properties 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 rubber members of functional parts such as tire carcass and anti-vibration rubber that require 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.

On the other hand, the use of carbon black having such a large particle size and a small specific surface area reduces the reinforcing property of the compounded rubber composition.

[Problems to be solved by the invention]

Therefore, if carbon black having a large particle size and a small specific surface area can be used and a high degree of reinforcement can be imparted to the compounded rubber composition, rubber for functional parts such as tire carcass and anti-vibration rubber can be obtained. It becomes ideal as a member.

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,
Aggregate Stokes carbon black having a small diameter (Japanese Patent Application Laid-Open No. 59-86461, Japanese Patent Application No. 61-33918).
No.), and carbon black (Japanese Patent Laid-Open No. 59-184231) in which the width of the aggregate Stokes equivalent diameter distribution is broadened. Generally, when the aggregate Stokes equivalent diameter becomes smaller, the distribution width also narrows. In the region where the nitrogen adsorption specific surface area (N ₂ SA) was 65 to 84 m ² / g, it was still difficult to achieve both high degree of reinforcement and low heat buildup.

As a result of continuous efforts to solve the problem, the present invention has a value for performing Stokes equivalent diameter distribution of aggregates on carbon black having such a specific surface area as Dst and Δ ▲.
▼, as well as iodine adsorption (IA), specific coloring power (Tin
Elucidating the fact that setting the b value defined by the equation in which t) is a variable within a specific range gives a compounded rubber composition a low heat buildup property while maintaining a high degree of reinforcement. , Which led to the development.

[Means for solving problems]

That is, the carbon black provided by the present invention has a nitrogen adsorption specific surface area (N ₂ SA) of 65 to 84 m ² / g,
The DBP oil absorption (DBP) belongs to the hard region of 90 to 115 ml / 100 g, ▲ ▼ in the aggregate Stokes equivalent diameter distribution showing a single peak is in the range of 88 to 102 nm, and ΔDst is in the range of 102 to 124 nm, and the following ( The carbon black whose b value defined by the formula (1) satisfies the relation of the following formula (2).

b = 0.67 × [ΔDst (nm)] ² / [▲ ▼ (nm)] × Tint (%)] / [IA (mg / g)] (1) 200 ≧ b ≧ 1.15 × [N ₂ SA] +30 (2) where IA is the iodine adsorption amount, Tint is the specific coloring power, ▲ ▼ is the maximum frequency of Stokes equivalent diameter in the aggregate Stokes equivalent diameter distribution by the centrifugal sedimentation method, ΔD
st indicates the difference between the Stokes equivalent diameters of two points, large and small, at which 50% of the maximum frequency in the distribution is obtained.

Generally, the low heat buildup required for rubber members of functional parts such as tire carcass and anti-vibration rubber has a nitrogen adsorption specific surface area (N
₂ SA) 85m ² / g or more, DBP oil absorption (DBP) 116
Not available above ml / 100g. On the other hand, nitrogen adsorption specific surface area (N ₂ SA) 64 m ² / g or less, DBP oil absorption (DBP) 8
If it is less than 9 ml / 100 g, sufficient reinforcement cannot be obtained.

Further, in the conventional technology, the nitrogen adsorption specific surface area (N ₂ SA)
65-84 m ² / g, DBP oil absorption (DBP) 90-115
Even with ml / 100g, it is not possible to obtain the required low heat buildup and reinforcement.

It is known that the exothermicity can be lowered by widening the width of the aggregate distribution, but generally, the Stokes equivalent diameter also increases accordingly, and the reinforcing property largely decreases.

In the present invention, the width of the aggregate Stokes equivalent diameter distribution is widened to lower the heat generation property, and the Stokes equivalent diameter is relatively reduced to increase the proportion of the fine aggregates, thereby reducing the reinforcing property. It is preventing. Due to the increase in the proportion of micro-aggregates, the specific coloring power becomes higher than that of the conventional carbon black having the same level of iodine adsorption.

The b value is an index for achieving both high degree of reinforcement and low heat buildup,
When it is smaller than 1.15 × [N ₂ SA] +30, the heat generation property does not decrease to the required level, and when it is 200 or more, the reinforcing property becomes insufficient.

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

(1) a nitrogen adsorption specific surface area _{(N 2 SA) ASTM D3037-86 "} Standard Test Method f
or Carbon Black-Surface Area by Nitrogen Adsoptio
n According to Method B.

The nitrogen adsorption specific surface area of IRB # 5 by this measuring method is 8
It will be 0.3 m ² / g.

(2) Iodine adsorption amount (IA) According to JIS K6221-82 "Testing method for carbon black for rubber", section 6.1.1.

(3) DBP oil absorption (DBP) According to JIS K6221-82 "Testing method for carbon black for rubber", section 6.1.2, oil absorption A method (mechanical method).

(4) Specific tinting strength (Tint) In accordance with JIS K6221-82 "Testing method for carbon black for rubber", section 6.1.3, a comparative sample was tested with IRB # 3.
And

(5) Value representing the Stokes equivalent diameter distribution of aggregate by centrifugal sedimentation method (▲ ▼, ΔDst) JIS K6221 (1982) 5 A method of preparing a dry sample contains a small amount of a dry carbon black sample containing a surfactant. A 20 vol% ethanol aqueous solution is mixed to prepare a dispersion having a carbon black concentration of 50 mg / l, which is sufficiently dispersed by ultrasonic waves to obtain a sample. A disk centrifuge device (manufactured by Joyes Loebl, UK) was set at a rotation speed of 8000 rpm, 10 ml of a spin solution (2 wt% glycerin aqueous solution at a temperature of 25 ° C) was added, and then 1 ml of a buffer solution (20 vol% ethanol at a temperature of 25 ° C). Water solution). Next, carbon black dispersion 0.5 at a temperature of 25 ° C.
ml is added with a syringe to start centrifugal sedimentation, and at the same time, a recorder is operated to optically generate a distribution curve of aggregate Stokes equivalent diameter. The maximum frequency of Stokes equivalent diameter in the obtained distribution curve is ▲ ▼ (nm), and the maximum frequency is 5
Let ΔDst (nm) be the difference between the Stokes equivalent diameters of two points, large and small, at which 0% frequency is obtained.

ASTM D-24 Standard ref by this measurement method
erence Black C-3 N234 ▲ ▼ is 80n
m and ΔDst are 60 nm.

The carbon black of the present invention is provided with two generation units, each of which is composed of a combustion chamber having a combustion burner and a raw oil injection nozzle mounted on its head, and a pyrolysis conduit continuous with the combustion chamber. Using a Y-shaped oil-feeness black generation furnace in which carbon is convergingly coupled to a cylindrical main reaction zone, carbon black intermediate product gas streams generated in different series are simultaneously introduced into the main reaction zone at high speed to cause mutual collision. It is produced by the method (JP-A-59-49267). At this time, as generation conditions in each generation unit, the total air supply both, the fuel oil supply both, the fuel oil burning rate and the feed oil supply amount of the second generation series are set higher than those of the first generation series, and the feed oil is The retention time in the furnace of the produced carbon black flow from the injection position to the water cooling point at which the reaction was stopped was 10.4 to 15.
A carbon black having the characteristics of the present invention can be obtained by controlling within a range of 7 ms.

[Action]

In general, carbon black has a low specific surface area, a low structure, and a low heat buildup.
As the width of the aggregate Stokes equivalent diameter is increased, the reinforcing property decreases.

However, as in the present invention, for carbon blacks having the same level of specific surface area and structure, by reducing the width of the aggregate Stokes equivalent diameter distribution, the heat generation property is lowered and the Stokes equivalent diameter is made relatively small. ,
By increasing the proportion of micro-aggregates, a decrease in reinforcement is prevented.

〔Example〕

An internal diameter of 400 nm and a length of 800 mm with a combustion burner and a raw oil injection nozzle mounted on the head via a wind box.
Combustion chamber (of which 200 mm conical part) and inner diameter 80 m
a first generation part having a pyrolysis conduit of m and 700 mm in length;
Similarly, two generations of a combustion chamber equipped with a combustion burner and a raw oil injection nozzle and having an inner diameter of 650 mm and a length of 800 mm (of which 200 mm is a conical portion) and a second generation section having a pyrolysis conduit having an inner diameter of 110 mm and a length of 1000 mm are generated. The inner diameter of 300 mm and the length of 4000 mm in the latter part of the wide diameter part, and the inner diameter of 13
On the front surface of the main reaction zone, which was continuously connected to the front stage narrow-diameter portion having a length of 5 mm and a length of 850 mm, a Y-shaped structure oil fornel black generating furnace was installed, which was converged at an intersection angle of 60 °.

The stock oil has a specific gravity (15/4 ° C.) of 1.0703, an Engler viscosity (40/20 ° C.) of 2.10, a benzene insoluble content of 0.03%, a correlation coefficient (BMCI) of 140, and an initial boiling point of 1.
Aromatic hydrocarbon oil at 03 ° C., and as fuel oil, specific gravity (15/4 ° C.) 0.903, kinematic viscosity (50 ° C.) 16.
1 cSt, residual coal content 5.4%, sulfur content 1.8%, flash point 96
A hydrocarbon oil at ℃ was used.

Four types of carbon black of the present invention were produced by applying the generation conditions shown in Table I using the above-mentioned generation furnace, raw oil and fuel oil.

Table II shows the characteristics such as the nitrogen adsorption specific surface area (N ₂ SA) of each carbon black produced, and the b value and 1.15 ×.
It showed a value of _[N 2 SA] +30.

The Run Nos. 5 to 8 shown as comparative examples in Table II
Is a nitrogen adsorption specific surface area (N ₂ SA) and a DBP oil absorption amount (DBP) of the same level as those of the examples manufactured by the prior art.
It is a carbon black having.

Next, the various carbon blacks in Table II were blended with the natural rubber in the blending ratios shown in Table III.

Various rubber properties were measured on the rubber composition obtained by vulcanizing the compound of Table III at a temperature of 145 ° C. for 30 minutes. The results are shown in Table IV in correspondence with the carbon black Nos. In Table II.

The measuring method and the measuring condition of the rubber property are as follows.

(1) Loss coefficient (tan δ) The loss coefficient was measured using a Visco elastic spectrometer (manufactured by Iwamoto Seisakusho) under the following conditions.

Test piece Length 30mm, width 5mm, thickness 2mm Temperature 25 ° C Frequency 50Hz Dynamic strain rate ε ± 1% (2) Wear amount Using a Lambourn wear tester (mechanical slip mechanism),
The measurement was performed under the following conditions.

Specimen outer diameter 44 mm, thickness 10 mm Emery wheel GC type, grain size # 80, hardness H Relative slip ratio between emery wheel surface and specimen 24%, 60% Specimen rotation speed 535 rpm Test load 4 kg Added carborundum powder grain size # 80, addition amount 9 g / min (3) Others According to JIS K6301-75 "Vulcanized rubber physical test method".

Considering the results of Table IV together with the properties of Table II, the carbon blacks of the Examples are comparative examples in which the nitrogen adsorption specific surface area and DBP oil absorption amount, and the hardness, tensile properties, and abrasion resistance values are at the same level. The loss factor (tan δ) is smaller than
It also has high anti-repulsive elasticity and maintains a high degree of reinforcement,
It shows that low heat buildup is imparted.

On the other hand, in Comparative Example 5 in which the b value exceeds 200, the loss coefficient (tan δ) is low, but the tensile strength is significantly reduced and the wear resistance is also reduced. Also, the b value is 1.1.
In Comparative Examples 6 to 8 in which the value is less than 5 × [N ₂ SA] +30, the loss coefficient (tan δ) is high and low heat generation cannot be imparted.

〔The invention's effect〕

The carbon black provided by the present invention has a rubber composition obtained by blending the same with a combination of a high degree of reinforcement and low heat build-up, which have hitherto been considered to be difficult to achieve as anti-reverse properties. Performance is also maintained at a high level.
Therefore, it is useful as a rubber member for functional parts such as tire carcass and anti-vibration rubber.

Claims (1)

[Claims] 1. A nitrogen adsorption specific surface area (N ₂ SA) of 65 to 8
4m ² / g, DBP oil absorption (DBP) 90 ~ 115ml / 100
Aggregate that belongs to the hard system region of g and shows a single peak ▲ ▼ in the Stokes equivalent diameter distribution is 88 to 102n
m and ΔDst are in the range of 102 to 124 nm, and
Carbon black whose b value defined by the formula (1) satisfies the relation of the following formula (2). b = 0.67 × [ΔDst (nm)] ² / [▲ ▼ (nm)] × Tint (%)] / [IA (mg / g)] (1) 200 ≧ b ≧ 1.15 × [ N ₂ SA] +30 (2) where IA is the iodine adsorption amount, Tint is the specific coloring power, and ▲ ▼ is the Stokes equivalent diameter of the maximum frequency in the aggregate Stokes equivalent diameter distribution by the centrifugal sedimentation method. , ΔDst
Indicates the difference between the Stokes equivalent diameters of two points, large and small, at which 50% of the maximum frequency in the distribution is obtained.