JP2002327134A - Carbon black for tire tread rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon black capable of imparting high reinforcing effect and abrasion resistance without lowering the heat-generating characteristics of a compounded rubber and useful for a tire tread rubber. SOLUTION: The carbon black for tire tread rubber belongs to a hard region having a nitrogen-adsorption specific surface area (N2 SA) of 60-180 (m<2> /g) and a DBP absorption of 90-150 (cm<3> /100 g) and satisfies the relationships of formula (1): Vp>=0.00976×(DBP)+0.0006 and formula (2): Dmp>=-0.236×(N2 SA)+63.39, wherein Vp (cm<3> /g) is the void volume of aggregate measured by mercury intrusion method and Dmp (nm) is the mode diameter of the void of the aggregate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon black capable of imparting a high degree of reinforcement and abrasion resistance without impairing the exothermic characteristics of a compounded rubber, particularly a tire tread rubber used under severe running conditions. A carbon black suitable for use.

[0002]

2. Description of the Related Art The particle size, specific surface area, structure, etc. of rubber reinforcing performance of carbon black have conventionally been considered to be the dominant factors, and there are various varieties according to the characteristics of the rubber. When blending the rubber component with the rubber component, carbon black having a variety of characteristics suitable for the application member is selected and used.

For example, N110 (SAF) and N220 (ISAF) are used for rubber members which are used under severe running conditions such as a tire tread and require high wear resistance.
Hard carbon black having a small particle size, such as, for example, is applied. However, the abrasion resistance of the rubber composition can be improved as the particle diameter of the compounded carbon black is smaller and the specific surface area is larger, but on the other hand, other rubber physical properties, such as increased heat buildup, are disadvantageous. There is.

Therefore, in addition to the characteristic factors such as particle diameter, specific surface area, and structure which have been conventionally regarded as the basic characteristics of carbon black for rubber reinforcement, for example, the aggregation form of carbon black particles, the physicochemical Attempts have been actively made to improve the properties of carbon black compounded rubber by selectively improving micro physical properties such as properties.

[0005] For example, as a rubber composition Applicants having both a high degree of resilience and wear resistance, the nitrogen adsorption specific surface area (N ₂ SA) 58~139m ² / g, DBP absorption amount 90
150 cm ^3/100 g belong to the hard system region of the intergranular voids size Dp which is measured by mercury porosimetry (nm) is a relational expression [-0.
22 × (N ₂ SA) +60.8], a carbon black having a selective property not less than the value calculated by
A rubber composition (JP-A-3-50249) has been developed in which the rubber composition is blended in an amount of 30 to 100 parts by weight with respect to 0 part by weight.

Further, as a carbon black which imparts abrasion resistance and low heat build-up to a compounded rubber in a well-balanced manner, a nitrogen adsorption specific surface area (N ₂ SA) is 60 to 160 m ² / g, and a DBP absorption is 90 to 150 cm ^3. / 100g belongs to the hard system area, the aggregate void volume Vp (cm ³ / g) satisfies the requirement of the following formula (1), and the aggregate properties determined by the centrifugal sedimentation method are as follows:
A carbon black for a tire tread satisfying the requirement of the formula (2) (JP-A-3-121165) was developed and proposed. Vp ≧ 0.00976 × DBP−0.0358 (1) ΔDst / (0.601 × Dst + 4.02) ≦ 1.00 (2)

[0007]

However, in recent years, as the performance of automobiles has increased, the performance of the tire tread has also been required to have a high level of performance that can withstand more severe driving conditions.
There is a demand for the development of carbon black for tire tread rubber that can impart even higher reinforcement and wear resistance without impairing the heat generation characteristics of the compounded rubber.

In view of the above situation, the present inventors have conducted intensive studies, and as a result, in the furnace carbon black belonging to the hard system region, the aggregate void volume is relatively large with respect to a certain structure level. It was also confirmed that carbon black having a relatively large aggregate void diameter per fixed particle diameter can significantly improve the reinforcing property and abrasion resistance without impairing the heat generation characteristics of the compounded rubber.

The present invention has been developed on the basis of this finding, and its object is to provide carbon black which can impart a high degree of reinforcement and abrasion resistance without impairing the heat generation characteristics of the compounded rubber, especially It is an object of the present invention to provide a carbon black suitable for a tire tread rubber used under severe driving conditions.

[0010]

The carbon black for a tire tread rubber provided by the present invention for achieving the above object has a nitrogen adsorption specific surface area (N ₂ SA) of 60 to 18.
^{0 (m 2 / g),} DBP absorption belongs to the hard system region of 90~150 (cm ³ / 100g), aggregate void volume is measured by mercury porosimetry Vp (cm ³ / g) and aggregates voids Mode diameter Dmp
(nm) satisfies the relationship of the following equations (1) and (2), respectively. Vp ≧ 0.00976 × (DBP) +0.0006 (1) Dmp ≧ −0.236 × (N ₂ SA) +63.39 (2)

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Among the characteristic requirements of the carbon black for tire tread rubber of the present invention, the nitrogen adsorption specific surface area (N
₂ SA) is 60-180 (m ² / g) and DBP absorption is 90-15
Characteristics Range of 0 (cm ³ / 100g) are those with a furnace carbon black belonging to a hard system region of normal varieties, which is a prerequisite for providing a high degree of reinforcement and abrasion resistance to compounded rubber . That is, the nitrogen adsorption specific surface area (N ₂ S
A) is 60 (m ² / g) and less than the DBP absorption 90 (cm ^3/100
If the amount is less than g), the compounded rubber cannot have sufficient reinforcement and wear resistance as a tire tread. On the other hand, if the nitrogen adsorption specific surface area (N ₂ SA) exceeds 180 (m ² / g), the dispersion in the rubber component is deteriorated, so that the reinforcing property and abrasion resistance of the compounded rubber are reduced and the heat generation property is impaired. And DB
P absorption amount exceeds 150 (cm ³ / 100g) and leads to a decrease in the ice skid performance compounded rubber, more will be impaired workability becomes high viscosity of the rubber.

The present invention relates to the above-mentioned nitrogen adsorption specific surface area (N ₂ SA).
60-180 (m ² / g), DBP absorption 90-150 (c
targeting carbon black having characteristics of m ^3/100 g), further aggregated forms of carbon black particles, agglomerates void volume is measured by mercury porosimetry Vp (cm ³ / g) and aggregates void mode diameter Dmp ( nm) satisfy the following relations (1) and (2), respectively. Vp ≧ 0.00976 × (DBP) +0.0006 ... (1) Dmp ≧ -0.236 × (N 2 SA) +63.39 ... (2)

The aggregate form of carbon black particles is generally such that several to several tens of basic carbon black fine particles are fused and bonded in an irregular and complex chain to form aggregates. Are formed from aggregates (agglomerates) that are entangled with each other or adhere and re-aggregate. In the compounded rubber, the agglomerates are loosened and dispersed in the rubber in an aggregated state, and the form of the aggregate mainly affects the rubber properties.

The aggregate (aggregate) of the carbon black particles is related to the structure. In the present invention, the value of the aggregate void volume Vp (cm ³ / g) measured by the mercury intrusion method is defined as the difference between the DBP absorption amount and the aggregate void volume Vp (cm ³ / g). In relation, Vp ≧
It is necessary to satisfy the relationship of 0.00976 × (DBP) +0.0006.

Carbon black having a large aggregate void volume Vp essentially has an aggregate structure with a well-developed structure, and when compounded with rubber, has a large interaction with the rubber during the compounding process, thereby reinforcing the compounded rubber. It functions to improve wearability and wear resistance. The selective property of the aggregate void volume Vp that satisfies the relationship of the expression (1), which is one of the main constituent requirements of the present invention, indicates a specific aggregate structure of carbon black having a highly developed structure. It is characterized by a large anisotropy of the aggregated form compared to the conventional carbon black of the same kind.

Furthermore, in the context of the present invention the value is a nitrogen adsorption specific surface area of the aggregate gap mode diameter Dmp (nm) as measured by mercury porosimetry _{(N 2 SA), (2} ) expression of Dmp ≧ -0 .2
It is necessary to satisfy the relationship of 36 × (N ₂ SA) +63.39.

The carbon black having a large aggregate void mode diameter Dmp also has an aggregate structure in which the structure is essentially developed, and has a large interaction with the rubber during the compounding process when compounded with the rubber. It functions to improve reinforcement and wear resistance. The selective property relating to the aggregate void mode diameter Dmp that satisfies the relationship of the formula (2), which is another main constituent requirement of the present invention, is a specific aggregate structure of carbon black having a highly developed structure. Which is characterized by a larger anisotropy of the aggregated morphology than conventional carbon black of the same kind.

The volume and diameter of the void formed by the aggregate of carbon black particles are affected by the form, size, distribution and the like of the aggregate. In the present invention, the value of the aggregate void volume Vp is set to a value not less than the value of the relational expression of the expression (1) in relation to the DBP absorption amount indicating the size of the structure of the carbon black, and the value of the aggregate void mode diameter Dmp Is set to a value greater than or equal to the value of the relational expression of equation (2) in relation to the size of the primary particles of carbon black, that is, the nitrogen adsorption specific surface area (N ₂ SA).

This structure level (DBP absorption amount)
A relatively large aggregate void volume Vp for
The effect of the relatively large aggregate void mode diameter Dmp on the nitrogen adsorption specific surface area (N ₂ SA) can improve the reinforcing property and wear resistance of the compounded rubber, and the nitrogen adsorption specific surface area (N ₂ Acting synergistically with the amount of SA) and DBP absorption, it is possible to impart a high degree of reinforcement and wear resistance without impairing the heat generation characteristics of the compounded rubber.

These characteristic values are measured by the following methods. Nitrogen adsorption specific surface area (N ₂ SA); m ² / g ASTM D3037-78 “Standard Methods of Testing
Carbon Black SurfaceArea by Nitrogen Adsorption ”M
According to ethod B. The measured value of IRB # 5 by this method was 80.3 m ² / g. DBP absorption; cm ³ / 100g JIS K6217-97 due to "test method of basic performance of the carbon black for rubber".

Agglomerate void volume Vp; cm ³ / g A carbon black pellet having a particle size of 250 to 500 μm dried according to JIS K6221-85 “How to prepare a dried sample” is used as a sample and a mercury porosimeter (Pore Sizer, manufactured by Micromeritics Co., Ltd.). 9300) dedicated cell (3cm
³ ) Put 0.2 g of the sample in
Pressurize to 0 psi and inject mercury to measure the capacitance (pF). The capacitance is obtained by measuring the capacitance between mercury inside the cell and an electrode outside the cell, and calculating the amount of mercury injected from the change in the capacitance. In addition, the aggregate void diameter calculated from the following equation is 0.1.
The cumulative volume of the void diameter from 0006 to 7.2 μm is defined as Vp.

[0022] Where X1: capacitance at 25 psi (pF), X2: capacitance at 30,000 psi (pF), W: weight of carbon black sample (g), CF: constant determined by cell,

When the relationship between the value of the aggregate void mode diameter Dmp; nm Vp and the void diameter at each pressure is graphed, an inflection point of a portion showing the maximum frequency of the void diameter appears.
The air gap diameter at this inflection point, that is, the air gap diameter showing the maximum frequency is defined as Dmp.

The carbon black of the present invention having the above-mentioned properties can be mixed with natural rubber, styrene-butadiene rubber, polybutadiene rubber, isoprene rubber, butyl rubber, various synthetic rubbers which can be reinforced with conventional carbon black, or a mixture thereof. Rubber component 10 such as blended rubber
A rubber composition for a tire tread is prepared by blending the rubber composition in an amount of 35 to 200 parts by weight with respect to 0 part by weight. In addition,
When compounding with the rubber component, necessary components such as a usual vulcanizing agent, a vulcanization accelerator, an antioxidant, a vulcanization aid, a softener, and a plasticizer are appropriately compounded.

The carbon black having these characteristics is produced by the reactor shown in FIG. In FIG.
Reference numeral 1 denotes a generating unit. The generating unit 1 has a cylindrical combustion chamber 5 provided with a combustion air inlet 2 and a combustion burner 3 at a head thereof, and a feed oil injection nozzle 4. And a continuous pyrolysis pipe 7 having a small diameter. The pyrolysis pipe 7 is coaxially connected to a succeeding narrow reaction zone 8 and a wide reaction zone 9. A generator 1 ′ having the same shape as the generator 1 is installed as a separate system from the generator 1, and a pyrolysis conduit 7 ′ of the generator 1 ′ is connected tangentially to the preceding narrow-diameter reaction zone 8. I have. In this way, the intermediate gas flows of carbon black generated in the two series of generating units 1 and 1 'collide with each other in the former narrow-diameter reaction zone 8, and then the thermal decomposition reaction is terminated in the latter wide-diameter reaction zone 9. By doing so, carbon black is produced.

[0026]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples.

Examples 1 to 6 and Comparative Examples 1 to 7 Two series of generators 1 comprising a combustion chamber (inner diameter 400 mm, length 800 mm), a conical section length 200 mm, and a pyrolysis conduit (inner diameter 60 mm, length 500 mm) , 1 'and inner diameter 90mm, length 70
0 mm pre-stage narrow-diameter reaction zone, inner diameter 200 mm, length 200
The reaction furnace shown in FIG. 3 was installed in which a 0 mm rear-stage wide-diameter reaction zone was connected. The pyrolysis conduit 7 'is connected at a position 150 mm from the downstream end of the pre-narrow reaction zone, and a ring member 10 with a drawing ratio of 0.65 is provided at a position 50 mm from the downstream end of the pre-narrow reaction zone. Was.

This reaction furnace allows the specific gravity (15/4
° C) 1.0703, viscosity (engler 40/20 ° C) 2.1
0, benzene insoluble content 0.03%, correlation coefficient (BMCI) 14
0. Aromatic hydrocarbon oil having an initial boiling point of 103 ° C and specific gravity (15/4 ° C) 0.903 viscosity (CST 50 ° C) for fuel oil
1. A hydrocarbon oil having a residual carbon content of 5.4%, a sulfur content of 1.8% and a flash point of 96 ° C was used. Using this reactor, the feedstock oil and the fuel oil, the reaction conditions shown in Table 1 and Examples 1 to 6,
And carbon blacks of Comparative Examples 1 to 7 were produced.

[0029]

[Table 1]

The properties of these carbon blacks were measured and are shown in Table 2. Table 2 also shows the characteristics of commercially available carbon black as a reference example.

[0031]

[Table 2] Note: * 1 Carbon black for commercially available rubber Reference Example 1; ASTM code N110 (Tokai Carbon Co., Ltd., Seast 9) Reference Example 2; ASTM code N220 (Tokai Carbon Co., Ltd., Seast 6)

These carbon blacks were blended in a natural rubber at the blending ratio shown in Table 3, and the blend was vulcanized at a temperature of 145 ° C. for 40 minutes to prepare a rubber composition.

[0033]

[Table 3]

For each of the produced rubber compositions, the Lambourn abrasion (slip ratio: 24%), the loss factor (tan δ) and the tensile stress (300% modulus) were measured by the following methods. The results obtained are shown in Table 4. Indicated. The loss factor (tan
FIG. 1 shows the relationship between δ) and tensile stress (300% modulus), and FIG. 2 shows the relationship between the loss factor (tan δ) and the amount of wear (slip rate 24%).

Abrasion: The abrasion was measured using a Lambourn abrasion tester (mechanical slip mechanism) under the following conditions. Test piece: thickness 10 mm, outer diameter 44 mm Emery wheel: GC type, particle size # 80, hardness H Carborundum powder with addition: particle size # 80, addition amount about 9 g / min Relative slip ratio between emery wheel surface and test piece: 24% Test piece rotation speed: 535 rpm Test load: 4 kg

Loss coefficient (tan δ); Visco Elastic Spect
Using a romwter (manufactured by Iwamoto Seisakusho), the loss factor (tan δ) was measured under the following conditions. Test piece: thickness 2mm, length 30mm, width 5mm Frequency: 50Hz Dynamic strain rate: ± 1% Temperature: room temperature

Tensile stress (300% modulus); Test piece JIS using Toyo Seiki Seisakusho (Strograph AR)
No. 3, measured under the conditions of a tensile speed of 500 ± 25 mm / min.

[0038]

[Table 4]

From these results, it can be seen that the rubber compositions containing the carbon blacks of Examples 1 to 6 satisfying all the selective property requirements of the present invention have at least either the aggregate void volume Vp or the aggregate void mode diameter Dmp. Comparative Example 1 in which one of them does not satisfy the value of the relational formula
As compared with the rubber compositions of Nos. 1 to 7, the nitrogen absorption specific surface area (N ₂ SA) and the DBP absorption amount are at the same level, while maintaining the same loss coefficient (tan δ), the 300% modulus is higher,
It is recognized that the amount of wear is small.

That is, while Example 4 and Comparative Example 6 have the same level of nitrogen adsorption specific surface area (N ₂ SA) and DBP absorption amount, Comparative Example 6 has an aggregate void volume Vp of the formula (1) Does not satisfy the value of
When an δ was maintained at the same level (exothermic), the rubber composition of Example 4 was 30 times less than the rubber composition of Comparative Example 6.
It can be seen that the 0% modulus is high and the reinforcement is excellent, and the wear amount is low and the wear resistance is excellent.

The rubber compositions of Reference Examples 1 and 2 blended with commercially available carbon black have an aggregate void volume Vp and an aggregate void mode diameter Dmp of carbon black of:
Since they do not satisfy the relations of equations (1) and (2),
It can be seen that the modulus is lower by 300% than in the examples, is inferior in reinforcement, is large in the amount of wear, and is inferior in wear resistance.

[0042]

As described above, the carbon black of the present invention has a highly anisotropic aggregate structure with a highly developed structure, and has a high degree of reinforcement without impairing the heat build-up of the compounded rubber. And abrasion resistance can be imparted. Therefore, it is extremely useful as a carbon black for compounding a tire tread rubber used under severe running conditions.

[Brief description of the drawings]

FIG. 1 shows a loss factor (t) of a rubber composition according to an example and a comparative example.
It is a graph showing the relationship between anδ) and 300% modulus.

FIG. 2 shows a loss factor (t) of a rubber composition according to an example and a comparative example.
6 is a graph showing the relationship between anδ) and the amount of Lambourn wear (slip rate 24%).

FIG. 3 is a schematic side sectional view of a reactor used for producing the carbon black of the present invention.

[Explanation of symbols]

 1, 1 'generating section 2, 2' combustion air inlet 3, 3 'combustion burner 4, 4' feed oil injection nozzle 5, 5 'combustion chamber 6, 6' conical section 7, 7 'pyrolysis conduit 8, Front narrow reaction zone 9, Rear wide reaction zone 10, Ring member

Continued on the front page F term (reference) 4J002 AC011 AC031 AC061 AC081 BB181 DA036 4J037 AA02 DD01 DD06 DD07 DD17 FF18

Claims (1)

[Claims] 1. A nitrogen adsorption specific surface area (N ₂ SA) of 60 to 180.
(m ² / g), DBP absorption amount is 90~150 (cm ³ / 100g) Hard system belongs to the area, aggregate void volume is measured by mercury porosimetry Vp (cm ³ / g) and aggregates gap mode Diameter Dmp (n
m) satisfies the following expressions (1) and (2), respectively. Vp ≧ 0.00976 × (DBP) +0.0006 (1) Dmp ≧ −0.236 × (N ₂ SA) +63.39 (2)