JP3438827B2 - Method for producing carbon black - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon black capable of imparting excellent conductivity to resins, rubbers, paints and the like.
And a method for producing the same . [0002] Acetylene black has been used as an electrolyte absorbent for manganese dry batteries because of its high liquid absorption performance. In addition, acetylene black is characterized by having less metal impurities and less grit than furnace black, so that high purity is required in conductive compound fields such as electronic material components, and for use in the inner semiconductive layer of CV cables. Used in the field. However, when carbon black such as acetylene black is blended with resin and / or rubber to increase the conductivity of the compound, acetylene black has a higher volume resistivity than furnace black. Because of its large size, a large amount of filling was required to provide the target conductivity. Also, acetylene black has a problem that the viscosity of the compound is increased due to the developed chain structure, and the flexibility and workability during kneading are greatly impaired. As a method for improving the conductivity-imparting ability of acetylene black, an average particle size of 25 obtained by incompletely burning acetylene gas with air preheated to 600 ° C.
Acetylene black of 0 to 300 ° (Japanese Patent Publication No. 62-32227) or a specific surface area of 130 to 100 ° C. obtained by incomplete combustion of acetylene gas with a mixed gas flow of an oxygen-containing gas and water vapor.
400m ² / g acetylene black (Japanese Patent Publication 4-71109
Publication). Since the specific surface area of these acetylene blacks is as high as 100 m ² / g or more, the volume resistivity of the compound manufactured using the same is improved as compared with the case of using the general acetylene black, but the viscosity of the compound is greatly increased. And the flexibility and workability during kneading are greatly impaired. [0005] Since what is generally referred to as highly conductive furnace black has a specific surface area of at least 200 m ² / g, its flexibility is impaired when it is used as a compound. Some conductive furnace blacks have a specific surface area of less than 100 m ² / g, but the conductivity-imparting ability of these carbon blacks is higher than that of acetylene black but not sufficient. Furnace black is obtained by incomplete combustion of a raw material oil, so that impurities and grit of the raw material oil are mixed, so that the application field is more limited than that of acetylene black. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a carbon black having a large conductivity-imparting ability .
Is to provide a fabrication method. That is, according to the present invention, an acetylene gas is supplied from an acetylene gas supply port (1) provided at the top of a vertical pyrolysis furnace as needed. An upper cooling gas supply slit pipe (2) for supplying a raw material obtained by mixing an inert gas, a hydrogen gas, and an unsaturated hydrocarbon, and for injecting the raw material in a downward direction provided in a pyrolysis region of the raw material. And a lower cooling gas supply slit tube (3) provided at a lower portion of the slit tube (2) and jetting upward, to obtain a total of 0.8 mol per mol of acetylene gas.
BET specific surface area of 90 to 20 m, characterized in that hydrogen gas of about 1.1 mol is fed so as to collide with each other and pyrolysis is performed while partially cooling the pyrolysis area of the raw material.
2 / g, the thickness of the graphite crystal layer (L
c) is 19 to 25 ° . Hereinafter, the present invention will be described in more detail. The carbon black produced in the present invention is
The conductivity-imparting ability is enhanced by reducing the size of the graphite crystal layer. There is a deep relationship between the graphite crystal layer of carbon black and the ability to impart conductivity, and the conductive mechanism of the compound is performed by moving the π electrons of the graphite crystal layer of carbon black between separated particles. Acetylene black is characterized by a large graphite crystal layer. In general, it has been said that the larger the graphite crystal layer, the higher the conductivity-imparting ability becomes.However, this is not always accurate, and when a current is applied to carbon black having a large graphite crystal layer, π electrons are trapped in the particles and become larger. It is clear from the fact that some furnace black having a smaller graphite crystal layer exhibits superior conductivity than acetylene black having a larger graphite crystal layer. The higher the specific surface area of carbon black, the higher the ability to impart conductivity to the compound. However, in this case, the viscosity of the compound increases drastically, and the flexibility and workability during kneading are greatly impaired. In order to eliminate the problem and obtain a carbon black having a high conductivity-imparting ability, it is necessary to reduce the specific surface area and the thickness (Lc) of the graphite crystal layer. Therefore, as a result of various studies, the present invention has found that BE
The carbon black has a T specific surface area of 90 to ²⁰ m ² / g and a graphite crystal layer thickness (Lc) of 19 to 25 ° measured by a sealer method. In the conventional conductive furnace black, the Lc is 18 ° or less and the thickness of the graphite crystal layer is small. Therefore, the conductive furnace black having a low specific surface area has a remarkably low conductivity-imparting ability. Further, there is a method of improving the graphite crystal layer by heat-treating conductive furnace black or thermal black at a high temperature.
0 ° or more, and never reached the range of Lc targeted by the present invention. In the present invention, the carbon black Lc
When the angle exceeds 25 °, the transfer of π electrons between particles is not performed well, and when the angle is less than 19 °, the resistance of the carbon black particles increases, and in any case, the ability to impart conductivity is reduced. The thickness (Lc) of the graphite crystal layer in the present invention is a value measured by a sealer method described later. On the other hand, if the specific surface area of carbon black exceeds 90 m ² / g, the viscosity of the compound increases, and the flexibility and workability are greatly impaired. The lower limit of the specific surface area was set to 20 m ² / g for reasons of production. Such a material must be used without lowering the thermal decomposition temperature extremely until it becomes difficult to sustain the decomposition reaction of acetylene gas. Since it cannot be manufactured, this is practically impossible. The method for producing carbon black of the present invention comprises:
It is as follows. That is, the process of producing acetylene black can be divided into a first step of forming particle nuclei, a second step of forming a chain-like structure by collision of particle nuclei, and a third step of forming a crystal layer. Since acetylene black has a high decomposition temperature of acetylene gas, a graphite crystal layer remarkably develops. If the overall decomposition temperature of the acetylene gas is lowered, the graphite crystal layer of acetylene black is lowered and the specific surface area is extremely lowered, and it becomes difficult to maintain the decomposition reaction. In order to lower the graphite crystal layer while maintaining the decomposition reaction of acetylene black, it is necessary to lower the temperature only in the portion where the third-stage reaction is performed. As a method for controlling the decomposition temperature of acetylene gas, there is Japanese Patent Publication No. 57-29498. In this method, a cooling gas is supplied to a pyrolysis region to control the furnace temperature to 1900 to 2400 ° C. to produce acetylene black having a high structure. Tokiko 57
The method of JP-A-29498 is intended to uniformly lower the decomposition temperature of acetylene gas, and it is necessary to feed a large amount of gas in order to reduce the graphite crystal layer using this method. Since the overall reaction temperature is lowered, the specific surface area of acetylene black is extremely reduced and the acetylene black is not decomposed, so that the carbon black targeted by the present invention cannot be produced. The present inventors have further studied the method of supplying the cooling gas in the thermal decomposition of acetylene gas. As a result, the cooling gas was introduced into the thermal decomposition region from two places, an upper part and a lower part, and from the lower part upward. The carbon black of the present invention can be produced by causing them to collide with each other by flowing downward from the upper part and efficiently cooling a part of the pyrolysis region without dispersing the cooling gas. That's what I found. Also, in this case,
It has been found that the graphite crystal layer of acetylene black can be made smaller without causing an extreme decrease in specific surface area by partially cooling the vicinity of about 600 mm away from the acetylene gas supply port. As the cooling gas used in the present invention, an inert gas such as nitrogen or argon is effective, but hydrogen gas is optimal for efficiently cooling a high-temperature hydrogen atmosphere in a pyrolysis furnace. The cooling gas supply position is in the pyrolysis region, and specifically, 450 to 550 m from the acetylene gas supply port 1.
It is desirable to be at a position separated by m and a position separated by 700 to 800 mm. In this case, the inlet of the slit pipe 2 for feeding the upper cooling gas is inclined downward by about 40 to 50 degrees, particularly about 45 degrees, and the inlet of the slit pipe 3 for feeding the lower cooling gas is upward. 40-50 towards
The inclination is about 45 degrees. At angles other than this angle, the cooling gas in the upper portion and the lower portion does not sufficiently collide with each other, so that partial cooling cannot be performed efficiently. The same applies to the case where the upper and lower cooling gas supply positions are provided in ranges other than the above. The amount of the cooling gas supplied is 0.8 to 0.8 to 1 mol of acetylene gas, including the upper and lower supply amounts.
Suitably, it is 1.1 mol. If the total cooling gas supply is small, the graphite crystal layer is not sufficiently reduced, and if the total cooling gas supply is large, the graphite crystal layer is too low and the conductivity-imparting ability is reduced. I do. As for the ratio of the upper cooling gas and the lower cooling gas to be supplied, upper cooling gas: lower cooling gas = 0.9: 1.1 to 1.1: 0.
The ratio is preferably set to 9, and if the ratio deviates significantly, the effect of the collision of the cooling gas is weakened and the temperature of the entire pyrolysis region is lowered. The specific surface area of acetylene black can be slightly adjusted by the amount of hydrogen gas supplied to the upper cooling gas and the lower cooling gas. However, an inert gas such as nitrogen or argon for controlling the reaction temperature or a hydrogen gas. Is preferably mixed with acetylene gas. Also, unsaturated hydrocarbons such as benzene, ethylene and butadiene can be mixed with the acetylene gas. The conductive composition is prepared by blending the carbon black produced in the present invention with a resin and / or rubber .
(Hereinafter, also referred to as “the conductive composition of the present invention”) . The carbon black produced by the present invention has a low specific surface area and excellent conductivity-imparting ability, so that it can be filled in a large amount, and becomes a highly conductive composition which does not impair the flexibility and workability of the compound. Conductive furnace black with a high specific surface area has excellent conductivity-imparting ability, but compound viscosity increases and high blending becomes difficult, and conductive furnace black and acetylene black with low specific surface area have high compoundability even if they are highly filled. The conductivity does not improve much. The mixing ratio of the carbon black produced in the present invention varies depending on the intended conductivity, but is 5 to 100 parts by weight with respect to 100 parts by weight of the resin and / or rubber.
Parts by weight are common. If the amount is less than 5 parts by weight, the resistance of the compound tends to vary, and if it exceeds 100 parts by weight, the flexibility and workability of the compound are impaired. The conductive composition of the present invention can be applied to cable semiconductors, conductive rubber, sheet heating elements, conductive adhesives, binders for conductive paints, antistatic sheets and the like. The resins used in the present invention include bisphenol type epoxy resin, phenol novolak type epoxy resin, alicyclic type epoxy resin, heterocyclic type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, and halogenated epoxy resin. Epoxy resin such as resin, polybenzimidazole, polybenzoxazole, polybenthiazole, polyoxadiazole, polypyrazole, polyquinoxaline, polyquinazolinedione, polybenzoxazinone, polyindrone,
Polyquinazolone, polyindoxyl, silicone resin, silicone-epoxy resin, phenol resin, melamine resin, urea resin, unsaturated polyester, polyaminobismaleimide, diallyl phthalate resin, fluororesin, T
PX resin (methylpentene polymer “trade name of Mitsui Petrochemical Company”), polyamide such as polyimide, polyamideimide, polyetherimide, 66-nylon and MXD-nylon, amorphous nylon, polyester such as polybutylene terephthalate and polyethylene terephthalate, Polyphenylene sulfide, modified polyphenylene ether, polyarylate, wholly aromatic polyester,
Polysulfone, liquid crystal polymer, polyetheretherketone, polyethersulfone, polycarbonate, maleimide-modified resin, ABS resin, AAS (acrylonitrile / acrylic rubber / styrene) resin, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin and the like. . The rubber used in the present invention is a rubber such as natural rubber, butyl rubber, acrylic rubber, ethylene propylene rubber, silicone rubber, polyester elastomer, polybutadiene and the like. The conductive composition of the present invention may further contain benzoguanamine, 2,4-dihydrazino-6-
Imidazole derivatives such as methylamino-S-triazine, 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, various amine complexes of boron fluoride, trisdimethylaminomethyl Reaction of phenol, 1,8-diazabicyclo (5,4,0) -undecene-7, tertiary amine compound such as benzyldimethylamine, dicyandiamide, bisphenol epoxy resin or cresol novolak epoxy resin with ammonia The resulting amino alcohol compound, a nitrogen-containing curing (acceleration) agent such as adipic hydrazide, phenol novolak,
Phenolic curing agents such as cresol novolac, acid anhydride curing agents such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride; triphenylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, and tolylphosphine , 1,2-bis (diphenylphosphino) ethane, bis (diphenylphosphino) methane, and other organic phosphine-based curing (acceleration) agents can also be contained. Further, the conductive composition of the present invention may contain a catalyst, a lubricant / release agent, a stabilizer, a light stabilizer, a coloring agent, a flame retardant, a coupling agent, etc., if necessary. it can. Examples of the catalyst include curing catalysts such as bis- (tributyltin) oxide, tin dioctenoate, antimony octoate, tin butyrate, lead monoxide, lead sulfide, and lead carbonate; polymerization catalysts such as platinum compounds; benzoyl peroxide; A vulcanizing agent such as dicumyl peroxide is used. As the lubricant / release agent, carnauba wax, montana wax, polyester oligomer, silicone oil, low molecular weight polyethylene, paraffin, metal salt of linear fatty acid, acid amide, ester and the like are used. Examples of the stabilizer include 2,6-di-tert-butyl-4-methylphenol, 1,3,5-tris (2-methyl-4-hydroxy-5-tert-butylphenol) butane, distearylthio Dipropionate, trinonylphenyl phosphite, tridecyl phosphite and the like are used. Examples of light stabilizers include 2,2'-dihydroxy-4-methoxybenzophenone, 2 (2'-hydroxy-5-methylphenyl) benzotriazole, 4-t
-Butylphenyl salicylate, ethyl-2-cyano-
3,3-diphenyl acrylate and the like are used. As a coloring agent, red iron oxide, carbon black and the like are used. As the flame retardant, antimony trioxide, antimony tetroxide, triphenylstibine, hydrated alumina,
Ferrocene, phosphazene, hexabromobenzene, tetrabromophthalic anhydride, tricresyl phosphate, tetrabromobisphenol A, brominated epoxy derivatives and the like are used. As coupling agents, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-
silane coupling agents such as β- (aminoethyl) -γ-aminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane,
Titanium-based coupling agents such as isopropyltriinstearoyl titanate, dicumylphenyloxyacetate titanate, bis (dioctylpyrophosphate) oxyacetate titanate, and isopropyltridecylbenzenesulfonyl titanate; aluminum-based coupling agents such as acetoalkoxyaluminum diisopropylate Are used. The present invention will be described below in more detail with reference to examples and comparative examples. The physical properties of carbon black were measured according to the following. (1) Specific surface area (m ² / g): BET1 by nitrogen adsorption
Point method (2) Graphite crystal layer thickness (Lc) (）): Calculated from the (002) diffraction line in the X-ray diffraction method using Cu-Kα ray according to the following Sealer's formula. Lc = (180 · K · λ) / (π · β · COS θ) K: Form factor (using 0.9) λ: X-ray wavelength (1.54 °) θ: (002) Diffraction line absorption band The angle β at which the maximum value is obtained: β: (002) The half-width in the diffraction line absorption band is indicated by an angle. (3) Preparation of the compound: 30 parts by weight of acetylene black and EVA resin (Nihon Unica) 100 parts by weight of a product name "NUC-3145") is kneaded with a kneading tester (trade name "Laboplastograph R-60" manufactured by Toyo Seiki Seisaku-sho, Ltd.) having an internal volume of 60 ml at a blade rotation speed of 60 rpm and a temperature of 120C for 10 minutes. did. This kneaded material is pressed under heating at 180 ° C. to form a 2 mm thick plate.
Was prepared. (4) Volume specific resistance (Ω-cm): The test sample was cut into a 2 × 20 × 70 mm rectangular parallelepiped, and the electric resistance was measured using a digital multimeter (trade name “TR- manufactured by Takeda Riken Co., Ltd.”).
6856 "). (5) Melt flow index (g / 10 minutes): A test sample was cut into a size of 2 × 5 × 5 mm, and heated at 200 ° C. with a melt flow indexer (trade name “melt indexer” manufactured by Takara Industries Co., Ltd.). Under 5kg weight 2
The weight of the compound per 10 minutes flowing from a nozzle of mm was measured. Example 1 The acetylene gas pyrolysis furnace used had a total length of 4.4 m.
It is a vertical furnace with an inner diameter of 0.4 m, in which the inner surface of a casing 5 is lined with a refractory brick 4. A slit tube having an inner diameter of 23 mm was provided as an acetylene supply port 1 at the top of the pyrolysis furnace, and an inner diameter 1 inclined 45 degrees downward at a position 450 mm away from the acetylene supply port 1.
Two 7 mm cooling gas feeding slit pipes 2 are provided. Further, at a position 750 mm away from the acetylene supply port 1, a cooling gas feeding slit pipe 3 having an inner diameter of 17 mm and having a 45-degree slope is directed upward. Were installed. An acetylene gas is supplied at a rate of 22 m ³ / h from the acetylene supply port 1 of the pyrolysis furnace to start the thermal decomposition of the acetylene gas, and the upper cooling gas supply slit pipe 2 and the lower cooling gas supply slit pipe 3 are provided. The thermal decomposition was continued while supplying hydrogen gas at a rate of 12 m ³ / h from each of the samples, and the generated carbon black was collected according to a conventional method. Table 1 shows the physical properties of the carbon black. Example 2 Carbon gas was supplied in the same manner as in Example 1 except that 9 m ³ / h of hydrogen gas was supplied from each of the upper cooling gas feeding slit pipe 2 and the lower cooling gas feeding slit pipe 3. Black was manufactured. Example 3 Carbon black was produced in the same manner as in Example 1 except that hydrogen gas 13 m ³ / h was mixed with acetylene gas 22 m ³ / h. Example 4 2 l / h of benzene was added to 22 m ³ / h of acetylene gas.
Was prepared in the same manner as in Example 1 except that was mixed. Comparative Example 1 Carbon black was produced in the same manner as in Example 1 except that the upper cooling gas supply slit tube 2 was provided at a position 400 mm from the acetylene gas supply port 1. Comparative Example 2 Carbon black was produced in the same manner as in Example 1 except that the lower cooling gas inlet slit tube 3 was provided at a position 850 mm from the acetylene gas supply port 1. Comparative Example 3 The feed angle of the upper cooling gas feed slit tube 2 was 30 degrees downward, and the feed angle of the lower cooling gas feed slit tube 3 was 30 degrees upward. Except for this, carbon black was produced in the same manner as in Example 1. Comparative Example 4 The feed angle of the upper cooling gas feed slit tube 2 was set to 60 degrees downward, and the feed angle of the lower cooling gas feed slit tube 3 was set to 60 degrees upward. Except for this, carbon black was produced in the same manner as in Example 1. Comparative Example 5 The amount of hydrogen gas supplied from the upper cooling gas supply slit pipe 2 and the lower cooling gas supply slit pipe 3 was 8 m ³ /
A carbon black was produced in the same manner as in Example 1 except that the value was changed to h. Comparative Example 6 The amount of hydrogen gas supplied from the upper cooling gas feeding slit pipe 2 and the lower cooling gas feeding slit pipe 3 was 14 m ³ respectively.
A carbon black was produced in the same manner as in Example 1 except that / h was set. Comparative Examples 7 to 8 Commercially available acetylene black [trade name of Denka Black 50% Press, manufactured by Denki Kagaku Kogyo KK (Comparative Example 7), CHE]
Table 1 shows the physical properties of VRON CHEMICAL COMPANY's trade name “Shawinigan Black 50% Press” (Comparative Example 8)]. Comparative Examples 9 to 10 Commercially available conductive furnace black [Cabot Cor]
Table 1 shows the physical properties of the trade name “Vulcan XC-72” (Comparative Example 9) and the trade name “# 3050” (Comparative Example 10) manufactured by Mitsubishi Kasei Kogyo. [Table 1] From Table 1, it can be seen that the carbon blacks of the present invention obtained in Examples 1 to 4 have a low Lc and therefore have a low volume resistivity of the compound and an excellent conductivity-imparting ability, and a high melt flow index. It can be seen that the compound has excellent flexibility and fluidity. On the other hand, the carbon blacks obtained by the methods of Comparative Examples 1 to 6 have a large Lc and therefore a high volume specific resistance of the compound, and are inferior in conductivity-imparting ability as compared with the examples. The commercially available acetylene blacks of Comparative Examples 7 and 8 have a large Lc, so that the compound has a high volume resistivity and is inferior in conductivity to the examples. The conductive furnace black of Comparative Example 9 was
Since Lc is small but the specific surface area is high, the volume resistivity of the compound is excellent, but the melt flow index is low, and the flexibility and fluidity of the compound are inferior to those of the examples. The conductive furnace black of Comparative Example 10 has a low Lc and therefore has a high volume resistivity of the compound, and is inferior in conductivity-imparting ability as compared with the examples. According to the present invention, excellent conductivity-imparting ability is obtained, and by blending it with a resin and / or rubber, the conductivity is significantly increased without impairing the flexibility and workability of the compound. Made of carbon black
A fabrication method is provided.

[Brief description of the drawings] FIG. 1 is a schematic plan view of a pyrolysis furnace. FIG. 2 is a partial schematic sectional view of FIG. [Explanation of symbols] 1 Acetylene gas supply port 2 Slit tube for sending upper cooling gas 3 Lower cooling gas inlet slit tube 4 refractory bricks 5 Casing

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-56768 (JP, A) JP-A-62-187769 (JP, A) JP-A-8-504868 (JP, A) Carbon Black Association, Carbon Black Handbook, Book Publishing Co., Ltd., May 25, 1972, 2nd edition, pp. 166 to 174, p. 385 to 390 (58) Fields investigated (Int. Cl. ⁷ , DB name) C09C 1/48 C08K 3/04 C08L 21/00 C08L 101/00

Claims (1)

(57) [Claims 1] An acetylene gas supply port (1) provided at the top of a vertical pyrolysis furnace supplies an acetylene gas with an inert gas, a hydrogen gas, A raw material mixed with a saturated hydrocarbon is supplied, and a slit pipe (2) for supplying an upper cooling gas, which is provided in a pyrolysis region portion of the raw material and is injected downward, and a slit pipe (2). Further, from the lower cooling gas supply slit pipe (3) provided at the lower part for injecting upward, a total of 0.8 to 1.1 moles of hydrogen gas with respect to 1 mole of acetylene gas collide with each other. Wherein the BET specific surface area is 9 mm.
0 to 20 m2 / g, graphite crystal layer measured by the sealer method
Of carbon black having a thickness (Lc) of 19 to 25 ° .