JPH0625312B2 - Ferromagnetic carbon black and method of manufacturing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferromagnetic carbon black having electrical characteristics, particularly high magnetic performance, and a method for producing the same.

[Conventional technology]

Carbon black is widely used as a filler for reinforcing rubber in the fields of tires and various industrial rubber products, pigments such as printing inks and paints, coloring materials for resins and functional materials.

Since carbon black is made of carbonaceous material and has a certain degree of conductivity, it is also used as a conductive filler such as rubber or resin, but it does not originally have magnetic performance.
Therefore, if it is possible to impart magnetic performance to these carbon blacks, the magnetic black can be obtained based on the magnetic function in addition to the various functions such as the reinforcing property, coloring property, and conductivity unique to the carbon black in the compounded rubber or resin. It can be expected to be useful in the fields of electronic industry and mechanical industry such as pigments, inks, magnetic rubbers and magnetic resins.

There are various kinds of carbon black corresponding to the particle diameter, and generally, it has a chain structure in which spherical fine particles having an average particle diameter of 10 to 200 nm are fused and secondary aggregated. Moreover, the distribution of particle diameters is also wide with respect to the average particle diameter. Furthermore, the density of carbon black is about 1.8, which is very different from the density of metals.
Therefore, it is difficult to uniformly and highly microdisperse the carbon black and the magnetic metal fine powder by the secondary mixing method, and the carbon black is mixed with the matrix material such as rubber, resin, paint and ink. Also in the method in which the magnetic metal fine powder is added and mixed, it is difficult to stably and homogeneously disperse it because separation and the like occur in the mixing process. Furthermore, in a state where they are simply mechanically mixed and dispersed, a high degree of magnetic performance cannot be imparted because the magnetic metal powder is not fixed to carbon black.

As a magnetic carbon black, a carbon black pigment composition containing about 100 to 300,000 parts by weight of an element of Fe, Co, Ni or a mixture thereof per 1,000,000 parts by weight of carbon black and combined with carbon black has already been known. (Japanese Patent Publication No. 39-25277).
The production method of this product is in the reaction zone of carbon black.
A carbon black pigment composition is obtained by supplying an additive containing elements of Fe, Co, Ni and a mixture thereof.

[Problems to be solved by the invention]

However, in the above-mentioned prior art, no consideration has been given to the magnetic performance, the particle diameters of carbon black and magnetic fine particles, and their mutual relationship.

The present invention, as a result of pursuing the relationship between the particle size of carbon black and the particle size of magnetic particles and the magnetic properties, by setting the average particle size of the magnetic particles larger than the average particle size of carbon black The present invention has led to the development of the finding that the can be added.

[Means for solving problems]

That is, the ferromagnetic carbon black of the present invention is a magnetic carbon black in which magnetic fine particles are uniformly dispersed and fixed in carbon black, and the average particle size of the carbon black is 20 nm or less and the average particle size of the magnetic fine particles is 30 nm.
The above is characterized in that the magnetic fine particles are composed of at least one metal selected from Fe, Co, and Ni and a magnetic compound thereof.

Generally, carbon black completely burns a fuel such as light hydrocarbon oil or natural gas to form a high temperature combustion gas stream, and a hydrocarbon raw material is injected and introduced into the high temperature combustion gas stream to cause a thermal decomposition reaction. , Is manufactured by the method of converting to carbon black. The hydrocarbon raw material undergoes a rapid thermal decomposition reaction due to a high-temperature combustion gas flow, produces a nucleus by a complicated polycondensation reaction, and further, a chain structure is formed through primary particles due to the growth and aggregation of the nucleus.

The hydrocarbon raw material is injected and introduced into a high temperature combustion gas flow which is an oxidizing atmosphere, and when a part thereof is burned, it is rapidly pyrolyzed in a reducing atmosphere and converted into carbon black. At this time, when the metal compound is simultaneously injected and introduced, it is rapidly decomposed to form spherical fine particles of about 30 to 40 nm.

The magnetic fine particles are trapped and fixed between the chain-structured grains of carbon black, or partially fused and bonded to carbon black in the state of cementite or the like, or partially aggregated and integrated with the carbon black basic particles to form carbon black. It is uniformly dispersed and fixed in black in a stable state. The dispersion form of these magnetic fine particles is such that when the hydrocarbon raw material is thermally decomposed and the carbon black particle size is relatively large in the process of generating a nucleus by the polycondensation reaction and a process of producing a carbon black by the growth and aggregation of the nucleus. As the gas phase carbonization reaction, which is the basis of the growth of carbon black particles, progresses toward the inside of the carbon black particles, the product nuclei, which are the basic constituent elements of the carbon black particles, aggregate with the magnetic fine particles, which are the decomposition products of the metal compounds. The frequency of immobilization increases. On the other hand, in the case of carbon black having a relatively small particle size that is thermally decomposed in a higher temperature atmosphere, the magnetic fine particles have a strong tendency to be fused and bonded to the carbon black particles to be exposed and fixed.

The present invention, in the production process of this carbon black,
The average particle size of carbon black is set to be relatively small, and the average particle size of fine particles of a metal and its magnetic compound, which is a decomposition product of at least one metal compound selected from Fe, Co, and Ni, is relatively large. It is something to set. In this case, the average particle size of carbon black is set to 20 nm or less and the average particle size of magnetic fine particles is set to 30 nm or more to increase the frequency of magnetic fine particles fusion-bonded to carbon black particles and exposed and fixed. . As a result, carbon black is provided with a high degree of magnetic performance by the exposed magnetic fine particles.

In this case, if the size of the magnetic fine particles exceeds 1 μm, it may act as a contaminant in the composition. Therefore, it is desirable to control the maximum diameter to 0.5 μm or less and the average particle diameter to 70 nm or less.

This ferromagnetic carbon black can be manufactured using a normal carbon black reaction furnace.

That is, fuel and air are supplied to a wide-diameter combustion chamber provided in the furnace head to form a high-temperature combustion gas flow, and the high-temperature combustion gas flowing down a narrow-diameter reaction chamber coaxially connected to the wide-diameter combustion chamber. By injecting a hydrocarbon raw material into the stream and converting it into carbon black by a thermal decomposition reaction, then spraying water to the carbon black product gas stream flowing down the wide diameter reaction chamber continuing to the narrow diameter reaction chamber and cooling it. In a method for producing a carbon black in which a reaction is stopped, a hydrocarbon raw material and at least one metal compound selected from Fe, Co, and Ni are injected into a high temperature combustion gas flow having a flow velocity of 150 m / sec or more, and carbonization is performed. It is manufactured by adding and supplying oxygen gas from around the hydrogen source.

The hydrocarbon raw material is produced by injecting a narrow-diameter reaction chamber into a high-temperature combustion gas stream flowing at a high speed of 150 m / sec or more, thereby rapidly pyrolyzing it in a highly disturbed gas stream to produce carbon black particles. The diameter becomes smaller. Further, when oxygen gas is added and supplied from around the hydrocarbon raw material, combustion and thermal decomposition reaction are further promoted, and carbon black having a small particle size is produced. On the other hand, the magnetic fine particles generated by the thermal decomposition of the metal compound are relatively larger than the particle diameter of carbon black and are generated as particles having an average particle diameter of 30 to 40 nm because they are less affected by these thermal decomposition conditions.

As the metal compound, metallocene, which is an aromatic cyclic complex compound such as ferrocene, cobaltocene, and nickelocene, or a carbonyl complex compound is preferably used. This is because these compounds are easily decomposed by heat, and the change in particle size of decomposition products is smaller than that of carbon black. The metal compound is supplied to the narrow-diameter reaction chamber in a state of being dissolved or decomposed in the hydrocarbon raw material.

The chemical composition of the magnetic fine particles is, for example, when an iron compound is used, FeO, Fe ₃ O ₄ , γ-Fe ₂ O ₃ , α-Fe by X-ray diffraction.
It turns out that it consists of a composition such as. This composition can be adjusted by changing the pyrolysis conditions of the reactor. Further, if carbon black is produced by using an iron compound and a cobalt compound together as a metal compound, F
A carbon black in which fine particles of an e / Co alloy system are highly dispersed can be obtained, and more highly functional magnetism can be imparted.
In this way, the regulation control of magnetism is also possible.

As the hydrocarbon raw material, various aromatic hydrocarbons such as benzene, toluene, xylene and styrene, coal tar oil, bottom oil at the time of ethylene cracking and the like are used.

This ferromagnetic carbon black-containing gas stream is sprayed with water and cooled according to a conventional method, then separated and collected through an appropriate device such as a back filter.

[Action]

Based on the above structure, the ferromagnetic carbon black of the present invention is
Since the average particle size of magnetic fine particles that are metals such as Fe, Co, and Ni and their magnetic compounds is set to be relatively larger than the average particle size of carbon black, magnetic fine particles are fused to carbon black particles. The frequency of binding and exposure immobilization increases. Therefore, a high degree of magnetic performance can be imparted to the carbon black based on the strong magnetic action of the exposed and fixed magnetic fine particles.

〔Example〕

Cylindrical reaction zone in the combustion chamber where the air introduction duct, fuel burner and raw material injection nozzle were installed in the furnace head (narrow diameter reaction part: diameter 30 mm, length 200 mm, wide diameter reaction part: diameter 8
0 mm, length 1500 mm) is used in a series of reaction furnaces and Table I
Magnetic carbon black was manufactured under the conditions of. In addition,
The metal compound was introduced into the narrow-diameter reaction section (position of 50 mm upstream) in a state of being dissolved or solution-mixed with the hydrocarbon raw material, and oxygen gas was supplied from around the raw material injection nozzle.

Various properties of the various magnetic carbon blacks obtained by the above production method are shown in Table II in comparison with Run No. in Table I.

From the results of Table II, the magnetic carbon blacks of the present invention examples (Run Nos. 1 to 4) each had an average particle size of 20 as the constituent carbon black and magnetic fine particles.
It satisfies the requirements of not more than 30 nm and not less than 30 nm, and shows an extremely high level of magnetization characteristics. On the other hand, Comparative Examples (Run No. 5, 6) obtained under the manufacturing conditions in which oxygen gas was not supplied
The magnetic carbon black of No. 2 is significantly inferior to the magnetic properties of the invention examples in that the average particle diameter of the constituent carbon blacks is outside the requirements (20 nm or less) of the present invention.

In addition, Run No. 1 (invention example) and Run No. 5 (comparative example)
1 and 2 show the magnetization characteristic curve (BH hysteresis loop) of the above magnetic carbon, and FIGS. 3 and 4 show electron micrographs (magnification of 60,000) of the same sample. It can be seen from these figures that the magnetic carbon black of the present invention has higher magnetizing performance and better particle dispersibility than those of the comparative examples.

〔The invention's effect〕

The magnetic carbon black provided by the present invention exhibits a unique composite state in which magnetic fine particles are fusion-bonded to carbon black particles and exposed and fixed, and based on this property, in addition to the characteristics unique to carbon black, it is possible to obtain a high magnetic property. Performance is given. Therefore, it can be applied to various members such as electronic devices by dispersing and filling it in rubber, resin, ink, paint or the like.

[Brief description of drawings]

FIGS. 1 and 2 are magnetization characteristic curves (BH hysteresis loop) of magnetic carbon black. FIG. 1 is an example of the present invention (Run No. 1), and FIG. 2 is a comparative example (Run No. 5). belongs to. 3 and 4 are electron micrographs showing the particle structure of magnetic carbon black (magnification: 60,000 times).
FIG. 3 shows an example of the present invention (Run No. 1), and FIG. 4 shows a comparative example (Run No. 5).

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Claims (2)

[Claims] 1. A magnetic carbon black in which magnetic fine particles are homogeneously dispersed and fixed in carbon black, wherein the average particle size of carbon black is 20 nm or less, the average particle size of magnetic fine particles is 30 nm or more, and the magnetic property is magnetic. Fine particles are F
A ferromagnetic carbon black comprising at least one metal selected from e, Co and Ni and a magnetic compound thereof. 2. A high-temperature combustion gas flow is formed by supplying fuel and air to a wide-diameter combustion chamber provided in a furnace head, and flows down a narrow-diameter reaction chamber that is coaxially connected to the wide-diameter combustion chamber. A hydrocarbon raw material is injected into a high temperature combustion gas stream, converted into carbon black by a thermal decomposition reaction, and then water is sprayed onto a carbon black product gas stream flowing down a wide diameter reaction chamber continuing to a narrow diameter reaction chamber. In a method for producing carbon black in which the reaction is stopped by cooling, a hydrocarbon raw material and Fe, C
o, at least one metal compound selected from Ni
Magnetic particles are uniformly dispersed and fixed in carbon black characterized by being injected into a high-temperature combustion gas stream having a flow velocity of 50 m / sec or more and adding oxygen gas from the periphery of a hydrocarbon raw material. Carbon black having an average particle size of 20 nm or less, an average particle size of magnetic fine particles of 30 nm or more, and the magnetic fine particles of at least one metal selected from Fe, Co and Ni, and a magnetic compound thereof. A method for producing a ferromagnetic carbon black.