JP3020193B2 - Carbon black for compounding functional parts rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to interior and exterior parts of automobiles such as weather strips, radiator hoses, door packings, window frame seal glass runs, protection moldings, pulley belts, cable covers, belt hose cables, ropes, mats and the like. Carbon black for compounding rubber for functional parts that can be added to rubber components other than tires, such as industrial rubber parts, to give a matte product skin with excellent productivity without lowering other rubber performance .

[0002]

2. Description of the Related Art Since functional parts rubber used for interior and exterior parts of automobiles is required to have a stable use performance over a long period of time, a study has been made to improve the settability (compression set) and fatigue resistance. Has been actively tried. Among the techniques for improving the rubber performance of this type, the mode diameter (Dst) measured by the centrifugal sedimentation method of agglomerates (DCF method) is a means to solve the colloidal characteristics of the carbon black to be compounded.
Is 150 nm or more, the mode diameter (Dst) and its half-value width (Δ
(Dst) ratio (ΔDst / Dst) is 1.05 or more, and the ratio (B / T) of coloring power (T) to blackness (B) is 1.2 or more. (Japanese Patent Laid-Open No. 3-14
No. 848), natural rubber or diene-based synthetic rubber 100
Nitrogen adsorption specific surface area (N ₂ SA) ≦ 60 m ² / g, D
BP oil absorption ≤100ml / 100g, 130nm≤Dst≤220
a rubber composition containing 20 to 100 parts by weight of carbon black having selective properties of nm and ΔDst / Dst ≦ 0.95 (Japanese Patent Laid-Open No. 4-18438);
Nitrogen adsorption specific surface area (N ₂ SA) ≦ 60 m ² / g, D
A rubber composition (JP-A-4-18439) containing 20 to 100 parts by weight of carbon black having selective characteristics of st ≧ 130 nm and ΔDst / Dst ≦ 0.95 has been developed by the present applicant and has already been proposed. Have been.

In recent years, with the diversification of paint colors on automobile bodies, there has been a demand for automobile interior and exterior parts rubber and the like to have a product skin (black gloss) that matches the body color. In addition to the rubber properties such as low compression set and aging resistance, there is an increasing demand for matte black rubber from the aspect of design. In general, it is effective to mix carbon black with high structure properties to the rubber component in order to obtain a black glossy product skin, and conversely, to obtain a low glossy product skin in order to obtain a dull product skin. Means of blending carbon black or blending a large amount of white filler such as calcium carbonate has been adopted.

[0004]

However, the compounding of carbon black having a low structure characteristic and the compounding of a large amount of a white filler cause poor dispersion when kneading with a rubber component, resulting in a decrease in material strength. It is not preferable as a means of measure. For this reason, a method of blending high-structure and low-structure carbon black is also known, but it is difficult to keep the blending ratio constant, and special equipment and complicated steps are required for homogeneous mixing. There are disadvantages.

[0005] In many cases, a rubber product of functional parts is manufactured by extruding a rubber kneaded product containing carbon black and then continuously vulcanizing the product, thereby improving the productivity in this series of steps. To do so, it is necessary to increase the speed of the vulcanization line simultaneously with the extrusion line. However, the vulcanization speed is affected by the characteristics of the carbon black to be compounded. Particularly when carbon black with a large particle diameter is compounded, insufficient vulcanization occurs even if the speed of the vulcanization line is increased, and the material strength decreases. Invite.

The present inventor has diversifiedly studied the carbon black characteristics required for obtaining a functional part rubber having a black matte product skin without impairing other mechanical rubber performances using a single carbon black. As a result, carbon black having a structure index (ratio of DBP oil absorption to compressed DBP oil absorption) within a certain range at a specific surface area of a soft system level satisfies the above-mentioned required rubber performance, and at the same time, high-frequency vulcanization. The fact that the vulcanization efficiency was improved in the stage was confirmed.

The present invention has been developed on the basis of the above-mentioned findings, and has as its object to reduce the black gloss without lowering the mechanical rubber properties such as mechanical strength and low settability. An object of the present invention is to provide a carbon black for compounding functional parts rubber, which has a glossiness of 3 and can improve vulcanization efficiency and contribute to an improvement in productivity.

[0008]

The carbon black for compounding a functional component rubber according to the present invention for achieving the above object has a nitrogen adsorption specific surface area (N ₂ SA) of 45 to 65 m ² / g and a DBP of
The ratio of oil absorption (D ₀₎ and the compression DBP absorption _{(D 1) (D 0 /} D 1) is 1.
10 to 1.20 and the DBP oil absorption (D
₀ ) satisfies the characteristic requirement of 60 to 80 ml / 100 g.

Furthermore, in addition to these constituent requirements, the ratio (ΔDst / Dst) of the half-width (ΔDst) of the distribution of equivalent Stokes diameters to the mode diameter (Dst) of the equivalent Stokes diameter distributions
Is less than 0.80 or / and coloring power (T) and blackness (B)
If the ratio (T / B) satisfies the characteristic item of 1.10 or more at the same time, the object of the present invention functions more suitably.

The values obtained by the following measuring methods are used for the respective characteristics of the carbon black having the above-described structure. Nitrogen adsorption specific surface area (N ₂ SA); ASTM D3037-88 “St
andard Test Method for Carbon Black-SurfaceArea by
According to Nitrogen Absorption "Method B. The measured value of IRB # 5 standard carbon black by this method is 8
0.3 m ² / g. DBP oil absorption (D ₀ ): According to JIS K6221-82 “Test method for carbon black for rubber”, section 6.1.2, oil absorption A method (mechanical method). Compressed DBP oil absorption (D ₁ ); ASTM D3493-85a “Stan
dard Test Method for Carbon Black- DibutylPhthalat
e Absorption Number of Compressed Sample ”.

Dst mode diameter (Dst) and half width (ΔDs)
t): A carbon black sample dried according to JIS K6221 (1982) 5 “How to make a dry sample” is mixed with a 20% by volume aqueous ethanol solution containing a small amount of a surfactant to obtain a dispersion having a carbon black concentration of 50 mg / l. A sample is prepared and sufficiently dispersed with ultrasonic waves to obtain a sample. disk·
Centrifuge (Joyes Lobel, UK)
The rotation speed is set to 00 rpm, 10 ml of a spin solution (2% by weight glycerin aqueous solution, 25 ° C.) is added, and 1 ml of a buffer solution (20% by volume ethanol aqueous solution, 25 ° C.) is injected. Then, a carbon black dispersion at a temperature of 25 ° C. was added.
After adding 5 ml with a syringe, centrifugal sedimentation was started, and at the same time, the recorder was operated and the distribution curve shown in FIG. 1 (horizontal axis: elapsed time after adding the carbon black dispersion with the syringe, vertical axis: carbon black) (Absorbance at a specific point that has changed due to centrifugal sedimentation). Each time T is read from the dispersion curve and substituted into the following equation (Equation 1) to calculate the Stokes equivalent diameter corresponding to each time.

[0012]

(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 carbon black dispersion injection point (4.56 cm), r ₂ is the radius to the absorbance measurement point (4.82 cm), and 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 of the maximum frequency in the distribution curve of Stokes equivalent diameter and absorbance obtained in this manner (FIG. 2) is defined as the Dst mode diameter (nm), and 50% of the maximum frequency.
ΔDst is the difference (half-width) between the Stokes equivalent diameters of the two large and small points at which the frequency is obtained. ASTM by this measurement method
Dst of D-24 Standard Reference Black C-3 (N234)
Is 80 nm and ΔDst is 60 nm.

Coloring power (T); ASTM D3265-88
“Standard Test Method for Carbon Black, TintStreng
th ". Blackness (B): Carbon black sample dried according to JIS K6221 (1982) 5" How to make a dried sample ".
After adding an appropriate amount of linseed oil to 500 g and thoroughly kneading with a Hoover maller, a thin film is prepared with a 0.0015 inch film applicator, and the reflectance is measured with dencyclone (manufactured by Weleh, USA). The display of the measured value is IRB # 2
An index when the reflectance of the reference carbon black is set to 100.

Among the characteristic requirements of the carbon black for compounding functional component rubber according to the present invention, when the nitrogen adsorption specific surface area (N ₂ SA) is in the range of 45 to 65 m ² / g, suitable mechanical properties are imparted to the compounded rubber. It is also a prerequisite for increasing productivity. When the nitrogen adsorption specific surface area (N ₂ SA) is less than 45 m ² / g, the compression set resistance of the compounded rubber is improved, but the process time during vulcanization is significantly delayed, impairing productivity and reducing mechanical strength performance. I do. On the other hand, if the nitrogen adsorption specific surface area (N ₂ SA) exceeds 65 m ² / g, the vulcanization rate is increased, but the dispersion in the rubber is deteriorated, and the compression set of the compounded rubber is significantly deteriorated.

DBP oil absorption (D ₀ ) and compressed DBP oil absorption (D ₁ )
The structure index, which is the ratio (D ₀ / D ₁ ) to 1.10
The reason for limiting to 1.20 is that it becomes an important characteristic factor for imparting a black matte product skin together with the range of DBP oil absorption (D ₀ ) described below without reducing productivity. . That is, when the ratio (D ₀ / D ₁ ) is less than 1.10, the granulated carbon black particles become hard, so that the dispersibility is reduced and the mechanical strength is reduced. On the other hand, when the ratio exceeds 1.20, although the dispersibility is improved and the mechanical strength is improved, the glossiness is increased and a product having no black gloss cannot be obtained. A particularly preferred range of the D ₀ / D ₁ ratio is a range of 1.11 to 1.17. When the DBP oil absorption (D ₀ ) constituting the D ₀ / D ₁ ratio is in the range of 60 to 80 ml / 100 g, it has good compounded rubber physical properties and low glossiness with suppressed black gloss. The product skin is obtained in the best balance.

In addition to the above carbon black selection characteristics,
Further, the aggregate distribution index, which is the ratio (ΔDst / Dst) of the half-width (ΔDst) of the aggregate Stokes equivalent diameter distribution to the mode diameter (Dst) of the aggregate Stokes equivalent diameter distribution, is 0.80.
When it is less than 1, as a result of promoting the carbon black network in the compounded rubber, the dielectric constant is improved together with the improvement of the mechanical strength, and it functions to increase the vulcanization rate during high frequency vulcanization. However, this ratio (ΔDst / Ds
When t) exceeds 0.80, formation of a network of carbon black in the compounded rubber is hindered, resulting in a decrease in mechanical strength, and further, a microwave vulcanization rate is slowed, which causes a loss of productivity. A preferred lower limit of the ΔDst / Dst ratio is
0.60.

Also, high blackness is required for interior and exterior rubber parts of automobiles and the like, but in order to effectively provide this rubber performance, coloring power (T) and blackness
It is preferable to select and use a carbon black characteristic that gives a ratio (T / B) of (B) of 1.10.

The carbon black of the present invention having the above characteristics is shown in FIGS. 3 (side sectional view), FIG. 4 (sectional view taken along line AA in FIG. 3) and FIG. 5 (sectional view taken along line BB in FIG. 3). like,
A combustion chamber 4 having a tangential air supply port 1 at the furnace head and a combustion burner 2 and a feed oil injection nozzle 3 mounted in the furnace axis direction, and a wide-diameter reaction through a coaxial drum-shaped narrow diameter portion 5. Part 6
A quench 7 and a quench 8 for water cooling are installed in two stages at two locations of the wide-diameter reaction section 6 and connected to a flue 9 at the end of the furnace. The raw material oil can be produced by a method in which the raw material oil is introduced in an atomized state into a high-temperature combustion gas stream formed by the oxidizing agent and flowing through the furnace.

More specifically, a high-aromatic heavy oil such as creosote oil, ethylene bottom oil or the like is used as a raw oil, and for example, a raw oil injection nozzle mounted at the center of the furnace head so as to be able to expand and contract in the axial direction of the furnace. 3 is used to atomize and inject at an appropriate position in the furnace as a fine particle stream sufficient to obtain a high degree of homogeneous mixing with the hot combustion gas injected from the surrounding combustion burner 2. At this time, the ratio between the total supply air amount and the total raw fuel oil introduction amount is controlled, and the combustion gas flow rate at the feed oil introduction position is reduced by 4%.
Conditions that are different from the conventional large particle carbon black production conditions (combustion gas flow rate: less than 40 m / sec, combustion combustion rate: 210% or more) such as maintaining the combustion combustion rate at 0 m / sec or more and the combustion rate at 210% or less. Set.

Further, the residence time of the carbon black product gas flow in the furnace is controlled in two stages, primary and secondary, and the residence time in the primary furnace (τ ₁ ; from the exit of the narrow diameter portion 5 to the former quench 7) and the secondary furnace The ratio (τ ₁ / τ ₂ ) of the internal residence time (τ ₂ ; from the exit of the narrow diameter portion 5 to the subsequent quench 8) is controlled to be 0.70 to 0.90. By this control, carbon black having a skeleton containing a relatively large amount of undeveloped crystallites is generated,
At the same time, a part of the reaction is stopped in a more uniform heat condensation polymerization process. After this generation stage, the structure index (D ₀ / D ₁ )
It is possible to produce carbon black that satisfies the characteristic requirements of the present invention, including adjustment of the carbon black.

The carbon black of the present invention is kneaded with a predetermined rubber component together with necessary components and subjected to a vulcanization treatment to obtain a desired functional component rubber product. As rubber components, styrene butadiene rubber, natural rubber, polybutadiene rubber,
Examples thereof include isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, and various other common synthetic rubbers and mixed rubbers that can be reinforced with carbon black. The amount of carbon black is 10 to 1 with respect to 100 parts by weight of the rubber component.
50 parts by weight, preferably 20 to 100 parts by weight,
It is kneaded with necessary components such as a vulcanizing agent, a vulcanization accelerator, an antioxidant, a softener, and a plasticizer, which are usually used, and continuously subjected to high-frequency vulcanization to produce a rubber product for a functional component.

[0024]

According to the carbon black characteristic requirements specified in the present invention, those having a nitrogen adsorption specific surface area (N ₂ SA) in the range of 45 to 65 m ² / g belong to soft carbon black, and reduce dispersibility and vulcanization characteristics. This is a prerequisite for imparting practical mechanical properties to the compounded rubber without using such properties, but it is not possible to obtain a black, matte product skin with this property alone. In addition to this, the carbon black DBP oil absorption (D ₀ ) and compression D
The structure index, which is the ratio (D ₀ / D ₁ ) of the BP oil absorption (D ₁ ), is in the range of 1.10 to 1.20, and the DBP oil absorption
When (D ₀ ) is in the range of 60 to 80 ml / 100 g, it is excellent in mechanical rubber properties such as mechanical strength and low sagging property, and at the same time gives well-balanced glossy product skin with suppressed black gloss. It is possible to do.

When the aggregate distribution index (ΔDst / Dst ratio) of carbon black is adjusted to less than 0.80 in addition to the above-mentioned limited characteristics, the networking effect of carbon black in the compounded rubber is promoted, and the mechanical properties of the rubber are improved. Not only does this result in an increase in the dielectric constant. The increase in the dielectric constant promotes the dielectric heat generation of the rubber compound by microwave per fixed exposure time during the high frequency vulcanization, and effectively functions to increase the vulcanization rate, thereby contributing to the improvement of productivity. Furthermore,
The blackness can be increased by setting the ratio (T / B) between the coloring power (T) and the blackness (B) to 1.10 or more.

The functions based on the above-described carbon black properties function comprehensively to provide a black, matte product skin while maintaining excellent mechanical properties such as excellent tensile strength, elongation and compression set. Rubber products can be manufactured with high productivity. Therefore, it is suitable as carbon black to be blended with functional component rubber, especially automotive interior / exterior component rubber.

[0027]

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

Examples 1 to 7 and Comparative Examples 1 to 12 A tangential air supply port 1 was mounted on the furnace head, and a feedstock injection nozzle 3 was provided at the center of the furnace shaft. A combustion chamber 4 (inner diameter 600 mm, length 800 mm) in which the downstream exit side converges gently, and a narrower portion 5 (inner diameter 50)
0 mm, length 200 mm), a wide-diameter reaction section 6 (900 mm inside diameter, 9000 mm long) in which a front quench 7 and a rear quench 8 are installed in two stages in the downstream area, and a bag filter at the downstream end A vertical flue 9 connected to the collection system of No. 1 was installed with a generator having the structure shown in FIG. The feed oil introduction point (nozzle injection hole) of the feed oil injection nozzle 3 was adjusted to be located at the narrow diameter portion 5.

Using the above-mentioned generator, carbon black was produced under the conditions shown in Tables 1 to 3. For feedstock, specific gravity (15/4 ° C) 1.073, viscosity (Engler 40/2
0 ° C) 2.10, toluene insoluble content 0.03%, correlation coefficient
(BMCI) 140, an aromatic hydrocarbon oil having an initial boiling point of 103 ° C., and a specific gravity (15/4 ° C.) 0.903 as a fuel oil,
A hydrocarbon oil having a viscosity (Cst / 50 ° C.) of 16.1, a residual carbon content of 5.4%, a sulfur content of 1.8%, and a flash point of 96 ° C. was used. Table 1
In 3, the combustion gas flow velocity refers to the combustion gas flow velocity at the feedstock introduction position, and the primary residence time (τ ₁ ) is the residence time of the generated carbon black-containing gas flow from the outlet of the narrow diameter section 5 to the former quench 7; The secondary residence time (τ ₂ ) is the residence time of the generated carbon black-containing gas stream from the outlet of the narrow diameter portion 5 to the subsequent quench 8.

Various properties of the carbon black produced under each generation condition are shown in Tables 1 to 3. In addition, carbon black which is out of any one of the characteristic requirements of the present invention is:
All are shown as comparative examples.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

Next, each of the carbon black samples shown in Tables 1 to 3 was compounded in the synthetic rubber at the compounding ratio shown in Table 4.

[0035]

[Table 4] [Table Notes] (1) "Esprene 501A" manufactured by Sumitomo Chemical Co., Ltd. (2) "PW-380" manufactured by Idemitsu Petrochemical Co., Ltd. (3) "Noxeller TT" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

Various rubber tests were carried out on the rubber compositions obtained by subjecting the compounds shown in Table 4 to high-frequency vulcanization at 150 ° C. for 40 minutes, and the measured results are shown in Tables 5 to 7. Further, in FIG. 6 a relationship graph between the [(TB × EB) × 10 ^4] value and blackness, Figure 7 the relationship graph of the [(TB × EB) × 10 ^4] value and the gloss [(TB × EB) × 10 ⁴ ] and the dielectric constant are shown in FIG. The measurement of the rubber properties was performed on the surface skin in accordance with ASTM D2230 B method, and all other rubber tests were performed according to JIS K630.
1 According to “Vulcanized rubber physical test method”. Among them, blackness (L ^* ) is measured using a color difference meter (CR-200) manufactured by Minolta Camera Co., Ltd.
A gloss meter manufactured by Co., Ltd. was used. The dielectric constant and loss factor, which are indicators of vulcanization characteristics, are determined by Yokogawa Hewlett-Packard
Co., Ltd., using Q meter, room temperature, frequency 20MHz
It measured on condition of.

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

As is clear from consideration of the results in Tables 5 to 7 and the corresponding graphs in FIGS. 6 to 8, the carbon blacks of the examples are more blended than the carbon blacks of the comparative examples which do not satisfy any of the characteristic requirements of the present invention. Excellent tensile strength, elongation and compression set equal to or better than rubber, good surface texture with relatively low blackness and gloss, and a high level of dielectric constant in a well-balanced manner Is admitted.

[0041]

As described above, according to the present invention, it is possible to provide a compounded rubber with a black gloss and a product surface having a low gloss without deteriorating mechanical properties, and to improve the vulcanization efficiency during high frequency vulcanization. It is possible to provide a carbon black that can be effectively improved. Therefore, various functions such as automotive interior / exterior parts such as weather strip, radiator hose, door packing, window frame seal glass run, protection molding, pulley belt, etc., industrial rubber parts such as cable covers, belt hose cables, ropes, mats, etc. It is extremely useful as carbon black for compounding rubber of parts.

[Brief description of the drawings]

FIG. 1 is a distribution curve showing changes in absorbance due to centrifugal sedimentation of carbon black and elapsed time from the addition of a carbon black dispersion at the time of measurement of Dst.

FIG. 2 is a distribution curve showing the relationship between Dst and absorbance obtained when measuring Dst.

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

FIG. 4 is a sectional view taken along line AA of FIG.

FIG. 5 is a sectional view taken along the line BB in FIG. 3;

FIG. 6 shows ((TB / EB) × 10) according to an example and a comparative example.
⁴ ] is a graph showing the relationship between the value and blackness.

FIG. 7 shows ((TB / EB) × 10) according to an example and a comparative example.
^-4 ] is a relationship graph between value and gloss.

FIG. 8 shows ((TB / EB) × 10) according to an example and a comparative example.
⁴ ] is a graph showing a relationship between a value and a dielectric constant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tangential air supply port 2 Combustion burner 3 Feed oil injection nozzle 4 Combustion chamber 5 Narrow diameter part 6 Wide diameter reaction part 7 Front quench 8 Rear quench 9 Flue

Claims (3)

(57) [Claims] 1. A nitrogen adsorption specific surface area (N ₂ SA) of 45 to 65 m ^2.
/ g, the ratio of the DBP oil absorption (D ₀ ) to the compressed DBP oil absorption (D ₁ ) (D ₀ /
D ₁ ) is in the range of 1.10 to 1.20 and the DB
A carbon black for compounding functional parts rubber, which satisfies the characteristic requirement of a P oil absorption (D ₀ ) of 60 to 80 ml / 100 g. 2. The mode diameter of the Stokes equivalent diameter distribution of the aggregate.
(Dst) half-width of Stokes equivalent diameter distribution
The carbon black for functional component rubber compounding according to claim 1, wherein the ratio (ΔDst / Dst) of (ΔDst) is less than 0.80. 3. The ratio (T / B) of tinting strength (T) to blackness (B) is:
The carbon black for compounding functional parts rubber according to claim 1 or 2, which is not less than 1.10.