JP3456759B2 - Furnace carbon black - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can impart high abrasion resistance and high impact resilience to a compounded rubber at the same time in a well-balanced manner, and is mainly used for automobile tires, industrial hoses, belts and the like, and particularly The present invention relates to a furnace carbon black suitable for a fuel-efficient tire tread.

[0002]

2. Description of the Related Art As rubber performance of a tire tread, it has been an important issue to impart high abrasion resistance and high impact resilience at the same time, but especially when it is targeted for fuel-saving tire tires. It is essential to satisfy both of these performances at a high level. Generally, in order to impart these rubber performances from the surface of the compounded carbon black, the particle size is as small as possible (the specific surface area is large) with respect to the increase in abrasion resistance, and the carbon black having a large structure is often used. It is effective to compound the rubber component in the compounding ratio, and conversely, to give high impact resilience,
It is said that it is effective to blend carbon black having a large particle size (small specific surface area) and a small structure in a rubber component in a small blending ratio. However, it is impossible to expect to simultaneously impart high abrasion resistance and impact resilience to the compounded rubber by simply combining the basic properties of carbon black having such a trade-off relationship.

Therefore, in addition to basic characteristics such as particle diameter, specific surface area, structure, etc., the distribution width of the aggregate, the true specific gravity,
The research and development of capturing the characteristic side of carbon black by a new evaluation scale such as the void volume of the aggregate or the intergranular void diameter, and controlling the selective properties of them in a certain range to impart the rubber performance is actively pursued. There is. The applicant has also systematically continued research on this relationship, and has already made the following development proposals. (1) Nitrogen adsorption specific surface area (N ₂ SA) 65 to 84 m ² / g, the ratio (N ₂ SA / IA) of the nitrogen adsorption specific surface area (N ₂ SA) to the iodine adsorption amount (IA) is 1.10 to 10. Carbon black having a function of 1.35 or more, which is constituted by an iodine adsorption amount, a compressed DBP oil absorption amount, a blackness (blackness) and an aggregate mode diameter, of a certain value or more (JP-A-63-225639). (2) Nitrogen adsorption specific surface area (N ₂ SA) is 60m ² / g or more, compressed DB
Carbon black with a P oil absorption of 112 ml / 100 g or more and a mode of aggregate mode diameter and the same distribution above a certain value.
−53978 publication). (3) Nitrogen adsorption specific surface area (N ₂ SA) is 75 to 105 m ² / g, compressed DBP oil absorption is 110 ml / 1/100 g or more, and the true specific gravity per constant specific surface area is smaller than that of known carbon black. And a large aggregate void diameter and a distribution width per aggregate mode diameter of a certain value or more (JP-A-1-201367). (4) Nitrogen adsorption specific surface area (N ₂ SA) is 60 to 160 m ² / g, DB
A carbon black having a P oil absorption of 90 to 150 ml / 100 g and having a void volume Vp (ml / g) of the aggregate per constant DBP oil absorption larger than that of known carbon black (JP-A-2-32136). . (5) Nitrogen adsorption specific surface area (N ₂ SA) is 58 to 139 m ² / g, DB
A rubber composition having a P oil absorption of 90 to 150 ml / 100 g and having a certain ratio of carbon black having a pore diameter Dp (nm) between aggregates per certain specific surface area larger than that of known carbon black ( (JP-A-3-50249)
.

[0004]

However, in recent years,
Due to the trend toward low fuel consumption, the quality requirements for rubber such as tires are becoming more and more stringent, and it is becoming impossible to achieve the required characteristics sufficiently with the quality of conventional technology.

The present inventors have taken a viewpoint different from that of the prior art, focusing on not only the conventional morphological physical properties but also the surface interaction between the rubber polymer and carbon black, and the abrasion resistance and repulsion of the compounded rubber. As a result of intensive studies on the correlation between elasticity and carbon black properties, the CTAB adsorption specific surface area and the ratio of this to the iodine adsorption amount, compressed DBP oil absorption amount, aggregate Stokes equivalent diameter distribution mode diameter (Dst) and its half value In a furnace carbon black having a width (ΔDst) ratio within a specific range, when the water content under a certain condition, which is considered to be an indirect factor of surface interaction, is below a certain level indicated by the function of the CTAB adsorption specific surface area. Is
It has been confirmed that it is possible to combine a high degree of wear resistance and impact resilience with compounded rubber.

The present invention was developed on the basis of the above findings, and is capable of imparting a high level of abrasion resistance and impact resilience to a compounded rubber at the same time in a well-balanced manner, and is particularly suitable for a fuel-saving tire tread rubber. The aim is to provide a new furnace carbon black.

[0007]

The furnace carbon black according to the present invention for attaining the above-mentioned object is CT
Absorption specific surface area (CTAB) is 60-140m ² / g, compression DB
P oil absorption (24M4DBP) is 90 to 125 ml / 100g, ratio of CTAB adsorption specific surface area to iodine adsorption (IA) (CTAB / IA) is 0.98 to 1.20, mode diameter of aggregate Stokes equivalent diameter distribution ( Dst) is 60 to 130 nm, the ratio (ΔDst / Dst) of the half-value width (ΔDst) of the aggregate Stokes equivalent diameter distribution to the mode diameter (Dst) is in the range of 0.65 to 0.90, and the water content ( The structural feature is that Wm) satisfies the relationship of the following formula (1) without being subjected to a secondary treatment such as heat treatment or graphitization treatment. Wm × 10 ⁴ ≦ 1.25 CTAB ² +55 CTAB (1) However, Wm is the temperature of the glycerin 50% by weight aqueous solution 20
The water content (% by weight) of carbon black after standing for 3 days in an atmosphere of 80 ° C. and 80% relative humidity is shown.

The characteristics of the carbon black according to the present invention are:
The following measurement method shall be used. CTAB adsorption specific surface area (hereinafter referred to as "CTAB"); A
STM D3765-80 "Standard Test Method for
Carbon Black-CTAB (CETYL TRIMETHYL AMMONIUM BROMID
E) Surface Area ". Compressed DBP oil absorption (hereinafter referred to as" 24M ₄ DBP "); AS
TM D3493-91 "Standard Test Method for C
arbon Black-Dibu-tyl Phthalate Absorption Number o
f Compressed Sample ". Iodine adsorption amount (hereinafter referred to as" IA "); JIS K622
1-82 "Testing method for carbon black for rubber" 6.
According to section 1.1.

Dst mode diameter (hereinafter referred to as "Dst") and half width (hereinafter referred to as "ΔDst"); JIS K6221 (1)
982) 5) Dry carbon black sample is mixed with 20% by volume aqueous ethanol solution containing a small amount of a surfactant based on “How to make a dry sample” and the carbon black concentration is 50 mg.
Make a dispersion liquid of / l and disperse it sufficiently with ultrasonic waves to make a sample. Disk centrifuge device (UK Jo
Yes Lobel Co., Ltd. is set at a rotation speed of 8000 rpm, 10 ml of spin solution (2 wt% glycerin aqueous solution, 25 ° C.) is added, and then 1 ml of buffer solution (20 vol% ethanol aqueous solution, 25 ° C.) is injected. Then, after adding 0.5 ml of the carbon black dispersion liquid at a temperature of 25 ° C. with a syringe, the centrifugal sedimentation was started, and at the same time, the recorder was operated and the distribution curve shown in FIG. 1 (horizontal axis: carbon black dispersion liquid with a syringe). Elapsed time after addition, vertical axis: absorbance at a specific point changed due to centrifugal sedimentation of carbon black) are prepared. Each time T is read from this dispersion curve and substituted into the following equation (Equation 1) to calculate the Stokes equivalent diameter corresponding to each time.

[0010]

[Equation 1]

In Equation 1, η is the viscosity of the spin liquid (0.935
cp), N is the disk rotation speed (8000), r ₁ is the radius of the injection point of the carbon black dispersion (4.56 cm), r ₂ is the radius to the absorbance measurement point (4.82 cm), ρ _CB is the density of the carbon black ( g / cm ^3), the [rho _l is the density of the spin fluid (1.00178g / cm ^3).

The Stokes equivalent diameter and the Stokes equivalent diameter of the maximum frequency in the distribution curve (FIG. 2) of the Stokes equivalent diameters thus obtained are defined as the Dst mode diameter (nm), and 50% of the maximum frequency is obtained.
Let ΔDst be the difference (half-value width) between the Stokes equivalent diameters of two large and small points at which the frequency is obtained. ASTM according to this measurement method
D-24 Standard Reference Black C-3 (N234) Dst
Is 80 nm and ΔDst is 60 nm.

Water content (hereinafter referred to as "Wm"); JIS
K6221-82 "Testing method for carbon black for rubber" 10 g of a carbon black sample, which has been dried and precisely weighed according to the method of 6.2.1, A, is left in a desiccator having a relative humidity of 80% for 3 days to absorb the moisture of the carbon black. Measure the quantity. Wm (% by weight) is [(relative humidity 80%
Of the carbon black after standing in a desiccator for 3 days-the initial carbon black weight after JIS drying) x 100 / the initial carbon black weight after JIS drying].

Among the characteristic items of carbon black constituting the present invention, CTAB 60 to 140 m ² / g, 24M4DBP9
0-125 ml / 100g, CTAB / IA ratio 0.98-1.
20, Dst 60 to 130 ml / 100 g, ΔDst / Dst ratio of 0.
The range of 65 to 0.90 is a prerequisite for imparting both high impact resilience and high abrasion resistance to the compounded rubber. If CTAB is less than 60 m ² / g, a high degree of abrasion resistance will not be imparted, and if it exceeds 140 m ² / g, a high degree of impact resilience will not be obtained. A more preferable CTAB range is 65 to 12
It is 5 m ² / g. If 24M4DBP is less than 90 ml / 100 g, the abrasion resistance is deteriorated, and if it exceeds 125 ml / 100 g, the viscosity of the compounded rubber is increased and the workability is remarkably lowered. More preferred
The range of 24M4DBP is 95-120 ml / 100g. C
If the TAB / IA ratio is less than 0.98, high impact resilience cannot be obtained, and if it exceeds 1.20, the viscosity of the compounded rubber increases and the processability is impaired. Further, when Dst is less than 60 nm, the impact resilience is not improved, and when it exceeds 130 nm, the wear resistance decreases. A more preferable range of Dst is 70 to 120 nm. Further, if the ΔDst / Dst ratio is less than 0.65, high impact resilience cannot be obtained. If it exceeds 0.90, the wear resistance decreases.

In order to achieve the object of the present invention, in addition to these prerequisites, Wm of carbon black which is not subjected to a secondary treatment such as heat treatment or graphitization treatment selectively satisfies the relation of the above formula (1). It is essential to have the characteristics.
That is, the value of Wm × 10 ⁴ is [1.25 CTAB ² +5
5 CTAB] value is exceeded, either the wear resistance or the impact resilience is insufficiently improved, and the required rubber properties cannot be achieved. Wm is the following
When the relationship of the expression (2) is satisfied, a better compatibility of both rubber performances is achieved. Wm × 10 ⁴ ≦ 1.25 CTAB + 40 CTAB (2)

The carbon black of the present invention is provided with two generation units, each of which comprises a combustion chamber having a combustion burner and a raw oil injection nozzle at its head, and a pyrolysis conduit continuous with the combustion chamber. Using a Y-shaped oil furnace in which a conduit is convergently assembled in a cylindrical main reaction zone,
It is produced by a method in which the 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 (JP-A-59-49267). At this time, oxygen was added to the combustion air introduced from the furnace head of each generation series so that the oxygen concentration in the total air was 23 to 26% by volume, and further after the reaction, the oxygen was added to the main reaction zone after the converging association. 10 to 30% by volume of the residual gas after separating the generated carbon black with a bag filter etc. with respect to the combustion gas flow rate in the furnace
The furnace carbon black of the present invention can be obtained by controlling the conditions of each generation series and the residence time of the produced carbon black stream in the furnace.

As a rubber component which can simultaneously impart a high level of wear resistance and impact resilience in good balance by blending the furnace carbon black of the present invention, styrene butadiene rubber, natural rubber, polybutadiene rubber, isoprene rubber, chloroprene Rubber, acrylonitrile-
Butadiene rubber, ethylene-propylene rubber, various other commonly used synthetic rubbers that can be reinforced with carbon black,
Examples thereof include mixed rubber. The amount of carbon black compounded is 10 to 150 per 100 parts by weight of the rubber component.
The rubber composition is set to a weight ratio, preferably 20 to 100 parts by weight, and kneaded together with necessary components such as a vulcanizing agent, a vulcanization accelerator, an antioxidant, a vulcanization aid, a softening agent and a plasticizer. To get

[0018]

[Operation] Generally, the water content (Wm) of carbon black is CT
It is known that the correlation with AB is strong, and that Wm tends to increase as CTAB increases. The present invention, from the viewpoint of surface interaction between carbon black and polymer molecules, pays attention to the amount of adsorbed water, which is considered to be one of the indirect factors, and when the furnace carbon black satisfying the above-mentioned characteristic requirements was compounded in the rubber. It has been completed by clarifying the fact that an elastomer having both high abrasion resistance and high impact resilience, which has been improved from the conventional one, can be obtained. The improved carbon black for fuel-efficient tires that the applicant has proposed so far has a strong surface interaction and tends to have a high water adsorption amount, but the furnace carbon black of the present invention has a surface with an excellent physical property function. Despite the high interaction, they differ in that the amount of water adsorbed per constant surface area is relatively small, and this unique physical property has the greatest feature. The reason why such physical properties contribute to both high levels of wear resistance and impact resilience has not yet been elucidated in detail, but the physical properties of the balance between wear resistance and heat generation are better than those of conventional carbon black. It was clearly demonstrated by the present invention that the relationship was improved.

Carbon black having a small Wm per constant CTAB can be obtained, for example, by subjecting carbon black to a secondary treatment such as heat treatment or graphitization treatment. In this case, heat treatment in an inert atmosphere is performed. It is presumed that the surface functional group is released, and the surface activity becomes low (ultimately the surface state of graphite), resulting in a low water content. Therefore, even if Wm becomes low, the surface activity is insufficient, and the reinforcing property for the rubber component is significantly reduced.

The furnace carbon black of the present invention having a small Wm in the state where no secondary treatment such as heat treatment or graphitization treatment is applied has a relative surface functional group (hydrophilicity) involved in water adsorption as compared with the conventional carbon black. Can be considered to be less. However, it is not clear if the amount of total surface functional groups (including hydrophobic surface functional groups) is similarly low. In general, the surface interaction of rubber polymers with carbon black is significantly affected by the polymer species, however, furnace carbon blacks that meet the Wm characteristic requirements of the present invention are superior to conventional modified carbon blacks for all types of polymers. Demonstrate a considerable degree of improvement. This is because the furnace carbon black of the present invention has many surface functional groups (types of hydrophobic functional groups) effective for surface interaction with polymer molecules, or surface functional groups not beneficial for surface interaction with polymer molecules. There are few (types of hydrophilic functional groups), and in combination with the characteristic requirements that this peculiar surface texture is a prerequisite, both the excellent abrasion resistance and impact resilience of the compounded rubber are positively affected, and as a result, both It is presumed that the action of simultaneously imparting the properties in a well-balanced manner is exhibited.

[0021]

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

Examples 1-7, Comparative Examples 1-6, Reference Examples 1-
4 Combustion chamber with inner diameter of 300mm and length of 400mm (including conical portion 150mm) with combustion burner and raw oil injection nozzle attached to the head through a wind box and inner diameter of 60mm, length of 85
Two series of generators equipped with 0 mm pyrolysis conduit, with an inner diameter of 15
0 mm, 4000 mm long front part wide diameter part and inner diameter 200 mm,
An oil-furnace furnace having a Y-shaped structure was installed in front of the main reaction zone in a converging manner at a crossing angle of 60 °, which was connected to a wide-diameter portion of the rear stage of 3000 mm in length. Using this reactor, a certain amount of oxygen is added or not added to the combustion air introduced from the heads of both generation series, and the main reaction zone after the convergent coupling (at the position of 150 to 300 mm from the coupling point) High temperature residual gas (200 ~
Furnace Khan Black was produced by applying variable conditions with or without introducing (300 ° C.) (Examples 1 to 7 and Comparative Examples 1 to 6).

The feed oil has a specific gravity of 1.073 and a viscosity (
Engler 40/20 ℃) 2.10, toluene insoluble matter 0.0
3%, correlation coefficient (BMCI) 140, aromatic hydrocarbon oil with an initial boiling point of 103 ° C is used, and fuel oil has a specific gravity (15/4
C.) 0.903, viscosity (Cst / 50.degree. C.) 16.1, residual carbon content 5.4%, sulfur content 1.8%, and a hydrocarbon oil with a flash point of 96.degree.

Tables 1 and 2 show the conditions of generation during manufacturing. In the generation conditions, the residence time in the furnace is the residence time of the produced carbon black producing gas up to the water cooling point. The characteristics of the respective furnace carbon blacks produced are shown in Table 3 (Examples) and Table 4 (Comparative Examples). Among the characteristics, Tint is the coloring power (%) when IRB ^# 3 is used as a reference sample. Table 5 shows, as a reference example, characteristics of a commercial product of carbon black according to ASTM grade. Further, in FIG. 3, CTAB and [W
m × 10 ⁴ / CTAB]. From this graph, it is found that the characteristics of the examples satisfying the requirements of the present invention have relatively smaller Wm per CTAB than the comparative examples.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

[Table 5]

Each of the furnace carbon blacks shown in Tables 3 to 5 was blended with the natural rubber (RSS # 1) in the blending ratio shown in Table 6, and the blend was vulcanized at a temperature of 145 ° C. for 40 minutes to give the rubber. A composition was made.

[0031]

[Table 6]

Various rubber properties were measured for each of the obtained rubber compositions, and the results are shown in Table 7 (Examples), Table 8 (Comparative Examples) and Table 9 (Reference Examples). In addition, in each measurement test, the loss coefficient and the amount of wear were measured by the following methods, and all others were based on JIS K6301 "Vulcanized rubber physical test method".

Loss coefficient (tan δ); Visco Elastic Sp
An ectrometer (manufactured by Iwamoto Manufacturing Co., Ltd.) was used for measurement under the following conditions. In addition, the displayed value is 100 in Reference Example 2 (N339).
Is the index, and a smaller index value indicates lower exothermicity. Test piece: thickness 2 mm, length 35 mm, width 5 mm Frequency: 50 Hz Temperature: 60 ° C. Dynamic strain rate: 1.2% Lambourn abrasion amount (LA); Lambourn abrasion tester (mechanical slip mechanism) The measurement was performed under the following conditions. The amount of wear resistance shown is an index when Reference Example 2 (N339) is set to 100, and the larger the index value, the higher the wear resistance. Test piece: thickness 10 mm, outer diameter 44 mm Emery wheel: GC type, grain size # 80, hardness H added carborundum powder: grain size # 80, addition amount 9 g / min. Relative slip ratio between emery wheel surface and test piece: 24
%, 60% Test piece rotation speed: 535 rpm Test load: 4 kg

FIG. 4 shows the relationship between impact resilience and wear resistance (LA24%) in Examples and Comparative Examples, and FIG. 5 shows the same relationship between impact resilience and wear resistance (LA60%). Fig. 6 shows a relationship diagram between the loss coefficient (tan δ) and wear resistance (LA24%) in Examples and Comparative Examples, and Fig. 7 shows a similar relationship diagram between the loss coefficient and wear resistance (LA60%).

[0035]

[Table 7]

[0036]

[Table 8]

[0037]

[Table 9]

As will be apparent from a consideration of Tables 7 to 9 and FIGS. 4 to 7, the rubber compositions containing the furnace carbon black satisfying the characteristic requirements of the present invention are CTAB and
Both the impact resilience and the abrasion resistance are relatively improved as compared with the carbon black compounded rubber of the comparative example in which 24M4DBP is at the same level, and it is recognized that these two properties are simultaneously imparted in good balance. In addition, although the reference examples 3 and 4 are within the characteristic range of the present invention with respect to Wm,
In all cases, CTAB / IA, which is an index of surface activity, is low, and DBP and 24M4DBP deviate from the requirements of the present invention, resulting in poor impact resilience and abrasion resistance.

[0039]

Industrial Applicability As described above, according to the present invention, it is possible to provide a furnace carbon black which can simultaneously have a high balance of abrasion resistance and impact resilience against a compounded rubber. Therefore, it is extremely useful as a rubber-reinforcing carbon black for industrial fuel hoses, belts, etc., which are used particularly under severe conditions, including tread rubbers for fuel-efficient tires of automobiles.

[Brief description of drawings]

FIG. 1 is a distribution curve showing the change in absorbance due to centrifugal sedimentation of carbon black and the time elapsed since the carbon black dispersion was added during the measurement of Dst.

FIG. 2 is a distribution curve showing the relationship between Dst and absorbance obtained during Dst measurement.

FIG. 3 shows CTAB and [Wm in Examples and Comparative Examples.
It is a graph showing the relationship with x10 ⁴ / CTAB].

FIG. 4 is a graph showing the relationship between impact resilience and wear resistance (LA24%) in Examples and Comparative Examples.

FIG. 5 is a graph showing the relationship between impact resilience and wear resistance (LA60%) in Examples and Comparative Examples.

FIG. 6 is a graph showing the relationship between loss coefficient and wear resistance (LA24%) in Examples and Comparative Examples.

FIG. 7 is a graph showing the relationship between loss coefficient and wear resistance (LA60%) in Examples and Comparative Examples.

Claims (4)

(57) [Claims] 1. A CTAB adsorption specific surface area (CTAB) of 60 to 1
40m ² / g, compressed DBP oil absorption (24M4DBP) is 90-125
ml / 100g, ratio of CTAB adsorption specific surface area to iodine adsorption amount (IA) (CTAB / IA) is 0.98 to 1.20, mode diameter of aggregate Stokes equivalent diameter distribution (Dst) is 60 to 130 nm, and the above mode The ratio (ΔDst / Dst) of the half-value width (ΔDst) of the aggregate Stokes equivalent diameter distribution to the diameter (Dst) is 0.65 to 0.9.
A furnace carbon black having a water content (Wm) in the range of 0 and satisfying the relationship of the following formula (1) without being subjected to a secondary treatment such as heat treatment or graphitization treatment. Wm × 10 ⁴ ≦ 1.25 CTAB ² +55 CTAB (1) However, Wm is the temperature of the glycerin 50% by weight aqueous solution 20
The water content (% by weight) of carbon black after standing for 3 days in an atmosphere of 80 ° C. and 80% relative humidity is shown. 2. The furnace carbon black according to claim 1, wherein the water content (Wm) satisfies the relationship of the following formula (2). Wm × 10 ⁴ ≦ 1.25 CTAB ² +40 CTAB ... (2) 3. A CTAB adsorption specific surface area (CTAB) of 65 to 1
The furnace carbon black according to claim 1 or 2, which is in a range of 25 m ² / g. 4. The compressed DBP oil absorption (24M4DBP) is 95-1.
The furnace carbon black according to claim 1, 2 or 3 in the range of 20 ml / 100 g.