JP2003192941A - Soft-type furnace carbon black - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon black which can solve such problems as a reduction in dispersibility and the deterioration of reinforcing properties and extrudability, tending to occur with conventional soft-type carbon blacks blended in large amounts, even when the carbon black is blended in an amount more than those before with a polymeric material, particularly a rubber compound, and which can maintain a high resistance even when blended in a large amount. <P>SOLUTION: This soft-type furnace carbon black is characterized in that it comprises a furnace carbon black having an iodine adsorption (IA) of 15 mg/g or grater and below 25 mg/g, and a dibutyl phthalate absorption (DBPA) of 100 ml/100 g or greater and below 150 ml/100 g, wherein the characteristics of Stokes' diameter (Dst) of the aggregate, determined by the centrifugal sedimentation analysis, satisfy the formulas: D<SB>3</SB>Q-DQ≥120 (nm) and D<SB>2</SB>Q/ Dmax≥1.120 (wherein DQ is the Dst corresponding to 25% of the whole; D<SB>2</SB>Q is the Dst corresponding to 50% of the whole; D<SB>3</SB>Q is the Dst corresponding to 75% of the whole; and Dmax is the Dst of maximum frequency). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is excellent in dispersibility and processing characteristics while maintaining mechanical properties when compounded with a polymer material, especially rubber, and is superior to conventional carbon black even when compounded in a large amount. The present invention relates to a soft type furnace carbon black having electric resistance.

[0002]

2. Description of the Related Art Carbon blacks are classified according to the properties of rubbers, which are their main uses, that is, processability and reinforcing properties. As main soft carbon blacks, semi-reinforcing furnace carbon blacks (Semi Reinfo) are used.
rcing Furnace-SRF), general-purpose furnace carbon black (General Purpose)
Furnace-GPF), good extrusion carbon black (Fast Extracting Fur)
nace-FEF). The expression "soft type" is derived from the fact that a soft rubber composition is provided at the time of compounding the rubber, and has good workability, low heat generation,
It has properties such that it can be blended in a large amount, and is used as a filler for rubbers such as tire carcass, tubes, belts, sealing materials, weather strips, and plastics. It is well known that basic characteristics of carbon black include a surface area evaluated by iodine adsorption amount, nitrogen adsorption specific surface area and the like and a higher-order structure (structure) due to the connection of carbon black particles.

As described above, as the physicochemical properties of carbon black, the particle size and the structure are typical. However, it is becoming difficult to control the desired rubber properties with these two properties. , It has already been clarified that the size of the most frequent value in the aggregate distribution of the minimum variance unit and the width of the distribution width have a great influence on the physical properties of the final rubber. A drawback of the soft carbon black is that when it is blended in a large amount, the carbon black and the process oil agglomerate and it is difficult to uniformly disperse them in the matrix. In addition, sponge products containing carbon black and rubber products having a low hardness have low extrusion processability, which causes a problem in workability. Japanese Patent No. 2506951 describes a soft type furnace carbon black which is excellent in dispersibility when blended in a large amount, imparts impact resilience and reinforcing properties, and can significantly improve extrusion processability. However, when a demand has been made for a compounded rubber in which the content of the soft carbon black is higher, a new problem was faced in that the above-mentioned various effects were hardly exhibited or disappeared.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a soft carbon black described in the above patent publication when a large amount of carbon black is blended into a polymer material, especially a rubber blend, as compared with the conventional case. It is an object of the present invention to provide a carbon black capable of eliminating the deterioration of dispersibility and the deterioration of reinforcing property and extrusion processability that have occurred, and maintaining high resistance even at a high compounding ratio.

[0005]

As a result of intensive studies, the present inventors have found that the iodine adsorption amount (IA) is 15 to 25 mg /
g, dibutyl phthalate absorption (DBPA) is 100 to
While following the basic characteristics of the above-mentioned patent, which have the basic characteristics of relatively low surface area of 150 ml / 100 g and high structure, in addition to the aggregate characteristics and coloring power evaluated by centrifugal sedimentation analysis, the present invention It has been completed. The first aspect of the present invention is that the iodine adsorption amount (IA) is 15 (mg / g) or more and less than 25 (mg / g), dibutyl phthalate (DBP) absorption amount (DBPA).
Is 100 (ml / 100g) or more, 150 (ml / 10
In the furnace carbon black having a characteristic of less than 0 g), the characteristic of the Stokes diameter (Dst) of the aggregate measured by centrifugal sedimentation analysis is represented by the formula (a) D _3Q −D _Q ≧ 120 (nm), and D _2Q /Dmax≧1.120 (In the formula, D _Q is equivalent to 25% of the total Dst, D
_2Q corresponds to 50% of the total Dst, D _3Q corresponds to 75% of the total Dst, and Dmax is the most frequent Ds.
indicates t. ) Is a soft type furnace carbon black. The second aspect of the present invention is that the iodine adsorption amount (IA) is 15 (mg / g) or more and 25 (mg / g).
g), dibutyl phthalate (DBP) absorption (DB
PA) 100 (ml / 100g) or more, 150 (ml)
In the furnace carbon black having a characteristic of less than 100 g / 100 g), the characteristic of the Stokes diameter (Dst) of the aggregate measured by centrifugal sedimentation analysis is represented by the formula (a) D _3Q −D _Q ≧ 120 (nm), and D _2Q /Dmax≧1.120 (In the formula, D _Q is equivalent to 25% of the total Dst, D
_2Q corresponds to 50% of the total Dst, D _3Q corresponds to 75% of the total Dst, and Dmax is the most frequent Ds.
indicates t. ) And the specific coloring power (%) is represented by the formula (b): Specific coloring power (%) ≦ (IA) (mg / g) +27. A third aspect of the present invention is the furnace carbon black according to claim 1 or 2, wherein the iodine adsorption amount (IA) is 17 (mg / g) or more and 23 (mg / g).
Less, dibutyl phthalate (DBP) absorption (DBP
A) is 105 (ml / 100g) or more, 135 (ml /
3. A soft furnace carbon black according to claim 1 or 2, characterized in that it has properties of less than 100 g).

In the present invention, the iodine adsorption amount (IA) is set in the range of 15 to 25 mg / g, and the iodine adsorption amount (I
When A) is less than 15 mg / g, mechanical properties such as tensile strength are unsatisfactory, and when it exceeds 25 mg / g, the viscosity of the compound is increased in a large amount of compounding, resulting in dispersibility and extrusion properties. Has the drawback of decreasing. Particularly, the iodine adsorption amount (IA) is preferably in the range of 17 to 23 mg / g.

In the present invention, dibutyl phthalate (D
BP) absorption (DBPA) is 100-150 ml / 10
The range is 0 g, but when it is less than 100 ml / 100 g, the properties relating to processability such as a decrease in dispersibility and an increase in die swell are deteriorated, and 150 ml / 1
If it exceeds 00 g, there is a drawback that the viscosity of the rubber composition is likely to increase. Especially, dibutyl phthalate (DBP) absorption (DBPA) is 105-135m
A range of 1/100 g is preferred. In the aggregate mode diameter by centrifugal sedimentation analysis, D in the above formula (a)
The fact that the value of _{3Q- DQ} is larger than 120 (nm) means that the aggregate size distribution of the carbon black of the present invention is wider than that of the conventional carbon black, and D _2Q
/Dmax≧1.120, the value of the ratio of the cumulative halving value of the aggregate size value and the most frequent value is as high as 1.120 or more, and the ratio of the large aggregate is larger than that of the conventional carbon black. Means more. The characteristics related to these aggregates effectively contribute to the fact that the carbon black of the present invention can be easily dispersed in the polymer matrix more easily than the conventional carbon black, and the carbon black is uniformly dispersed in the matrix. It is presumed that the electrical resistance of the compound is increased by the inclusion of the polymer matrix between the aggregates. When the specific tinting strength (%) is larger than the value calculated by the formula (b) relative tinting strength (%) ≦ (IA) (mg / g) +27, carbon is mixed in a large amount in the rubber matrix. The black and process oil form agglomerates that make uniform dispersion in the rubber matrix difficult. Further, since the extrusion characteristics and compression set characteristics of the compounded rubber composition are deteriorated, it is necessary to have a specific tinting strength smaller than the calculated values.

[Measurement of Each Property] The physicochemical properties of the carbon black in the present invention are measured as follows. (1) Iodine adsorption amount (IA) JIS K 6217 (1997) 6. The amount of iodine adsorbed per unit weight (mg / g) is measured. (2) DBP absorption amount (DBPA) DB measured per the method described in JIS K 6217 (1997) 9.2A method and absorbed per 100 g
It is displayed by the volume of P (ml / 100 g). (3) DBP absorption of compressed sample (24M4DBP) JIS K 6217 (1997) 10. It is measured by the method described in 1. and is expressed as the volume of DBP absorbed per 100 g (ml / 100 g). In addition, 24M4
The sample used for DBP measurement is 165MP before measurement.
a (24000 psi), four times of compression and disentanglement are performed, and the DBP absorption of the sample after this treatment is measured. (4) Specific coloring power (tinting) JIS K 6217 (1997) 11. It is measured by the method described in 1) and displayed as an index (%) with respect to the standard carbon black for colorimetric test.

(5) Analysis of carbon black aggregate characteristics by centrifugal sedimentation analysis Measuring device: High-speed disc centrifugal ultrafine particle size analyzer (measuring device names: BI-DCP, BROOKHAVEN
Analytical measurement method by INSTRUMENTS CORPORATION) 10 mg of carbon black is weighed and put in a 100 ml beaker, and 0.1 ml of the surfactant Nonidet P-40.
(Manufactured by Nakarai Tisque Co., Ltd.) is added. After thoroughly kneading the carbon black and the surfactant into a paste,
50 ml of a 20% by volume ethanol aqueous solution was added, and an ultrasonic homogenizer manufactured by Nippon Seiki Co., Ltd. (US-1
Sonicate for 3 minutes at 50 T) to completely disperse. Disk rotation speed is 4000 rpm and 15 ml
Ion-exchanged water (spin solution) is injected into the disk. Further, 1 ml of 20% by volume ethanol (buffer solution) is injected into the disc. After 1 minute, 0.5 ml of the above carbon black dispersion was injected into the disk to start the measurement, and the Stokes equivalent diameter Dst of the aggregate corresponding to each time t was calculated from the following formula (1) from the distribution curve of elapsed time and absorbance. Calculate by

[Equation 1] In the formula (1), η is the viscosity of the solvent (mPa · s) ω is the disk rotation speed (rpm) Δρ is the density difference between the carbon black particles and the solvent (g / c)
m ³ ) Ri is the radius (cm) of the carbon black dispersion liquid injection point, Rd is the radius (cm) to the absorbance measurement point, and t is the time (minutes).

[Characteristic Evaluation of Aggregate Stokes Equivalent Diameter] FIG. 1 is a graph showing changes in elapsed time and absorbance during Dst measurement. FIG. 2 is a graph showing the frequency distribution of Stokes equivalent diameters obtained as a function of elapsed time. The solid curve indicates the frequency distribution of the Stokes equivalent diameter (most frequent value = 1.0). The curve by the broken line is a cumulative frequency curve (overall = 1.0). The time-absorbance shown in FIG. 1 is converted into FIG. 2 showing the Dst-absorbance relationship using the equation (1). In FIG. 2, a cumulative frequency curve with respect to Dst is drawn from the absorbance (frequency), Dst corresponding to 25% of the whole is D _Q , and Dst corresponding to 50% is D _{2 Q.}
Dst corresponding to (one of the indexes for judging the size of the aggregate size distribution) and 75% is defined as D _3Q . In the histogram of Stokes equivalent diameter of the aggregate obtained by the above measurement operation, the highest frequency (actually, the maximum absorbance because optical measurement is performed)
The Stokes-equivalent diameter that gives ## EQU1 ## is called Dmax, and is a standard showing another average size of the carbon black aggregate. Furthermore, Ds having a frequency value that is half the most frequent value
The difference between t (there are two) is defined as ΔDst.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Manufacturing Example JP-B-54-38068 (Applicant: Asahi Carbon)
Of the oil furnace 1 (diameter 1000 mm) shown in FIG. 3 having the same structure as that of the furnace described in 1 above, the raw oil spray nozzle 4 is inserted into the furnace from the central axis direction of the furnace head, and a pair of upper and lower is installed in the tangential direction of the furnace. To the first air holes A, A ', the second air holes B, B'and the holes A, A'provided in
Was installed, and the amount of introduced air from each air hole, the amount of auxiliary raw material introduced, and the amount of feedstock oil supplied were changed to produce soft furnace carbon blacks having different physicochemical characteristic values. For the control of DBPA, ordinary regulators were used appropriately. The properties of the feedstock oil are as shown in Table 1.

[0013]

[Table 1] Further, C heavy oil was used as an auxiliary raw material. The production conditions of carbon black are shown in Table 2 as an example and in Table 3 as a comparative example.

[0014]

[Table 2]

[0015]

[Table 3]

The physicochemical properties of the SRF grade carbon black obtained under the production conditions shown in Tables 2 and 3 are shown in Table 4 (Examples) and Table 5 (Comparative Examples).

[0017]

[Table 4]

[0018]

[Table 5] Manufacturing example No. Nos. 1 to 4 are soft carbon blacks according to the present invention. 5 to 11 are examples of carbon blacks out of conformity with any of the characteristic requirements of the present invention.

[Rubber compounding characteristics] The rubber vulcanizates obtained by vulcanizing the carbon blacks shown in Tables 4 and 5 in a rubber composition at a ratio shown in Table 6 and vulcanizing at 150 ° C. for 30 minutes are various. The properties were measured. The results are summarized in Tables 7 and 8.

[0020]

[Table 6] * 1 Product name: Nox Cellar M [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] * 2 Product name: Nox Cellar TT [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] * 3 Product name: Nox Cellar TRA [Ouchi Shinko Chemical Industry ( Co., Ltd.] * 4 Product name: Nox Cellar BZ [Ouchi Shinko Chemical Industry Co., Ltd.]

[0021]

[Table 7]

[0022]

[Table 8]

From the results of the rubber properties of Tables 7 and 8 in which the carbon blacks of the above-mentioned Examples and Comparative Examples were blended with EPDM, the effect of the carbon black of the present invention is shown by the dispersity, extrusion property, compression set, tensile property and volume. It will be described with the characteristic of resistivity. The above characteristics were measured as follows. Mooney viscosity: Measured by the method described in JIS K6300: 1994 “Unvulcanized rubber physical test method”, item 6. -Dispersion degree ... The vulcanized rubber was cut with a razor, and the cut surface was photographed at a magnification of about 30 times.
ld, 151, No. 3, page 41 (1964), the quality of the dispersion is judged by comparison with the aiming dispersion photograph (10 is the best). If it is determined to be in the middle, 0.
Add 5 (eg, the middle of 8 and 9 is labeled 8.5).・ Extrusion characteristics: Using a 50 mmφ rubber extrusion tester (manufactured by Futaba Manufacturing Co., Ltd.), a Garvey die (ASTM D2230)
Extruding unvulcanized rubber from (1) to measure the following properties. 1) Extrusion speed: Displayed as the length of rubber extruded per minute (cm / min). The larger the value, the better the processability. 2) Die swell (DS) ... Represents how much unvulcanized rubber that has passed through the die is swollen after being extruded. The smaller the value, the better the workability. D. S. = (S−S ₀ ) × 100 / S ₀ (%) (In the formula, S ₀ is the die area, and S is the sample area after extrusion.) Hardness ... JIS K6253: 1997 “Vulcanized rubber and heat The hardness of plastic rubber is measured by the method described in "5. -Volume resistivity ... Measured according to the method described in JIS K6911: 95 "General Test Method for Thermosetting Plastics" and "5.13 Resistivity". (I) No. 1 in which IA and DBPA are almost equal regarding the degree of dispersion. 1 and No. 5,
No. 2 and No. 6, No. 3 and No. 7 and No.
4 and No. Comparing No. 8 with each other, it can be seen that the dispersibility of the compound containing the carbon black of the present invention is higher by 1 point or more in any case, and the characteristics are improved. It is presumed that this is because the large aggregate occupies a large proportion as compared with the conventional carbon black and the property of high DBPA is combined, so that the aggregate is easily dispersed in the polymer matrix. (Ii) Extrusion characteristics When comparing the extrusion characteristics of each rubber compound in the same manner as in (i) above, the carbon black compound of the present invention has an improved extrusion speed per unit time. It is clear that the die swell numbers are also declining. (Iii) Compression set Similarly, when the compression set characteristics are compared by comparing the examples and the comparative examples as in the above (i), the carbon black of the present invention shows a numerical value several points lower than any of the comparative examples. , You can see that it has been improved. (Iv) Volume resistivity Generally, in order to obtain a rubber composition having a high resistivity, it is desirable to use a carbon black having a large particle size and a low structure, but when such a carbon black is used, it is processed. Property, and as a result, the reinforcing property also decreases. The carbon black of the present invention has specificity in the shape of DBPA and aggregate distribution, so that even when a large amount is blended, it is uniformly dispersed in the matrix, thereby obtaining a rubber composition having high resistivity. can do. From the comparison between Table 7 and Table 8, it is understood that the carbon black of the present invention has high resistivity but maintains mechanical properties such as tensile strength.

[0024]

As described above, the carbon black of the present invention has a lower Mooney viscosity than the conventional soft carbon black, and can exhibit good compression set characteristics. Utilizing this property, it is useful as a filling and reinforcing agent for functional parts such as sponge extruded products and low hardness rubber products which are difficult to extrude, anti-vibration rubber products and packing members.

[Brief description of drawings]

FIG. 1 is a graph showing a change in elapsed time and absorbance during Dst measurement.

FIG. 2 is a graph showing a frequency distribution of Stokes equivalent diameters obtained as a function of elapsed time. The solid curve is
The frequency distribution of the Stokes equivalent diameter is shown (most frequent value = 1.
0). The curve by the broken line is the cumulative frequency curve (overall = 1.
0).

FIG. 3 shows an example of a production furnace suitable for producing the carbon black of the present invention. (A) is a vertical sectional front view showing an example of a manufacturing furnace suitable for manufacturing the carbon black of the present invention. FIG. 3B is a sectional view taken along the line D-D in FIG.

[Explanation of symbols]

1 Oil furnace 2 combustion zone 3 reaction zone 4 Material oil spray nozzle 5 Auxiliary raw material introduction device 6 air ducts 7 air ducts A first air hole A'first air hole B second air hole B'second air hole

Claims (3)

[Claims] 1. The iodine adsorption amount (IA) is 15 (mg /
g) or more and less than 25 (mg / g), dibutyl phthalate (DBP) absorption (DBPA) is 100 (ml / 100)
Stokes diameter (Ds) of the aggregate measured by centrifugal sedimentation analysis in a furnace carbon black having characteristics of not less than g) and less than 150 (ml / 100g)
The characteristic of t) is equation (a) D _3Q −D _Q ≧ 120 (nm) and D _{2Q /} Dmax ≧ 1.120 (wherein, D _Q corresponds to 25% of the total Dst, D
_2Q corresponds to 50% of the total Dst, D _3Q corresponds to 75% of the total Dst, and Dmax is the most frequent Ds.
indicates t. ) Is a soft type furnace carbon black. 2. The iodine adsorption amount (IA) is 15 (mg /
g) or more and less than 25 (mg / g), dibutyl phthalate (DBP) absorption (DBPA) is 100 (ml / 100)
Stokes diameter (Ds) of the aggregate measured by centrifugal sedimentation analysis in a furnace carbon black having characteristics of not less than g) and less than 150 (ml / 100g)
The characteristic of t) is equation (a) D _3Q −D _Q ≧ 120 (nm) and D _{2Q /} Dmax ≧ 1.120 (wherein, D _Q corresponds to 25% of the total Dst, D
_2Q corresponds to 50% of the total Dst, D _3Q corresponds to 75% of the total Dst, and Dmax is the most frequent Ds.
indicates t. ) And the specific coloring power (%) is represented by the formula (b): Specific coloring power (%) ≦ (IA) (mg / g) +27. 3. The furnace carbon black according to claim 1 or 2, wherein an iodine adsorption amount (IA) is 17
(Mg / g) or more and less than 23 (mg / g), dibutyl phthalate (DBP) absorption (DBPA) is 105 (ml)
/ 100 g) or more and less than 135 (ml / 100 g), The soft type furnace carbon black according to claim 1 or 2, characterized in that