JPS60240768A - Production of electrically conductive carbon black - Google Patents

Abstract

PURPOSE:To form the titled carbon black suitable for use as an additive for resins, rubber, etc., by adding an aq. soln. of a copper compd. to a carbon black forming zone in the production of carbon black by the thermal cracking of hydrocarbon. CONSTITUTION:A raw hydrocarbon oil is ejected into a high-temperature stream of comsution gas formed by completely burning combustion air and fuel oil introduced through the top of a reaction furnace into the furnace, whereby the oil is thermally decomposed by imcomplete combustion to convert it into carbon black. The reaction mixture is quenched to stop the reaction and the formed carbon black is collected. In this process, an aq. soln. of a copper or silver compd. (e.g. copper sulfate or silver nitrate) is added to the carbon black forming zone. The compd. is uniformly captured by carbon black and at the same time the compd. is reduced to metal by a reducing gas, thus forming highly electrically conductive carbon black contg. microscopic copper or silver uniformly dispersed therein.

Description

[Detailed Description of the Invention] [Subject of the Invention] The present invention provides a method for achieving high electrical conductivity without reducing mechanical strength or processability such as kneading and moldability when blended with a resin or rubber component. The present invention relates to a method for producing conductive carbon black.

[Background of the invention]

As a filler for conductive resin compositions and rubber compositions,
Carbon black has been used for a long time, and various types have been developed.

In general, conductive carbon black is required to have a small particle size, large surface area (porosity), and large stracture, but unless a large amount of carbon black is blended into the resin or rubber component, conductivity cannot be imparted. Not enough effect.

For example, in applications where the volume resistivity is 2 Ω·a or less, it is necessary to incorporate more than a few parts by weight of carbon black. However, compositions containing such multi-lobed carbon black have a major disadvantage in that mechanical strength, wire crosstalk, processability such as moldability are significantly reduced.

Furthermore, in recent years, carbon black has been developed in which by-product carbon is heat-treated to give it a high degree of electrical conductivity, but it is extremely expensive and has the disadvantage that it is limited to special uses. Moreover, since the conductivity of this heat-treated by-product carbon itself is inferior to that of metal, there is a basic problem that it must be mixed in large quantities in order to impart a high degree of conductivity.

Therefore, metal powders such as silver and nickel are used as fillers for resin compositions and rubber compositions that require high conductivity.

Although these metal powders exhibit superior conductivity compared to carbon black, they are expensive, have a large specific gravity and are difficult to obtain a homogeneously dispersed composition, and have poor processability and mechanical strength. There are disadvantages such as a significant decrease in

[Structure of the invention]

When the present invention is blended into resin or rubber components, it is possible to impart high conductivity with a relatively small amount, and there is little loss of processability such as mechanical strength, wire crosstalk, and moldability. The object of the present invention is to provide a method for producing conductive carbon black having excellent conductivity at low cost.

That is, the structure of the present invention is a method for producing carbon black in which a hydrocarbon feedstock oil is injected into a high-temperature combustion gas stream to cause a thermal decomposition reaction to be converted into carbon black. It is characterized by adding an aqueous solution of a copper compound and/or a silver compound.

In general, carbon black is produced by introducing fuel oil and combustion air from the head of a reactor, and injecting hydrocarbon feedstock into the high-temperature combustion gas stream formed by complete combustion, causing incomplete combustion. It is produced by causing a decomposition reaction to convert it into carbon black, then rapidly cooling the carbon black-forming hot gas stream to stop the reaction, and then collecting it with a suitable collection device.

Therefore, when carbon black is produced by a thermal decomposition reaction, a portion of the hydrogen in the hydrocarbon feedstock is decomposed into hydrogen gas and is present together with a large amount of nitrogen gas in the carbon black production gas. Further, the carbon black produced gas also contains carbon monoxide gas produced by incomplete combustion of the hydrocarbon feedstock oil, and has a highly reducing mixed gas composition as a whole.

During the production of the above carbon black, the copper compound and/or silver compound added to the carbon black production zone of the reactor are immediately thermally decomposed by the high temperature combustion gas to produce oxides, which pass through the reactor together with the high temperature combustion gas into fine particles. It flows down as a stream of mist droplets. In order to easily adjust the amount of the copper compound and silver compound added, it is desirable to add them as an aqueous solution, and for example, water-soluble salts such as copper sulfate, copper nitrate, copper chloride, and silver nitrate are used.

This mist flow of copper and complex oxides is fixed and homogeneously dispersed in the produced carbon black when the hydrocarbon feedstock oil is thermally decomposed and converted into carbon black, and continues to exist in the carbon black produced gas. It is reduced to metallic copper and silver by reducing hydrogen gas and carbon oxide gas.

In the carbon black produced in this manner, metallic copper and silver are uniformly dispersed and fixed in a microscopic state, and the carbon black is collected under a reducing atmosphere.

〔Effect of the invention〕

According to the present invention, since highly conductive metals such as copper and silver are uniformly dispersed in the carbon black in a microscopic state,
Carbon black with significantly improved conductive performance can be produced.

Therefore, when blended into resin or rubber components, it is possible to impart a high degree of conductivity with a relatively small amount, which prevents a decrease in mechanical strength and processability such as wire crosstalk and moldability. can.

Furthermore, conductive carbon black can be produced easily by using a normal reactor and adjusting the generation conditions as appropriate, and there is no need to particularly increase the surface area or struttle, so conductive carbon black can be produced at low cost.

[Embodiments of the invention]

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

Example 1 A copper sulfate aqueous solution (concentration o, 5%) was added to the carbon black production zone of reactor 9 for carbon black production, and production conditions were set appropriately to produce carbon blacks with different nitrogen adsorption specific surface areas and DBP oil absorption amounts. Manufactured. The amount of the copper sulfate aqueous solution added was determined so that the ratio of copper dispersed and fixed in the carbon black was a predetermined ratio, and various furnace carbon blacks having different copper contents were manufactured. Typical characteristics of the obtained furnace carb/black are shown in Table 1.

Table 1 These carbon blacks were mixed with high-density polyethylene (Mitsui Petrochemical Co., Ltd. "Hi-Zex 21") under the following mixing conditions.
00JPJ) It was blended at a ratio of 25 parts by weight to 1 o o overlapping parts.

Mixing device; Labo Plast Mill (Toyo Seiki Seisaku rupture 28-
125 type) Temperature: 170°C Patch capacity: 48CC/batch Mixing time - After adding carbon black 10 axioms After filling a predetermined amount of high density polyethylene and carbon black into the chamber, mix it at 170°C for 10 minutes and press. A thin plate molded product with a thickness of 1.5 ml was obtained by molding. A sample measuring 15 Qu in length, 20 U in width and 1.5 Cu in thickness was punched out from this molded product, and the volume resistivity was measured by the method of 8R work 82501, and then the tensile strength of the sample was measured. The measurement results are shown in Table 2 in comparison with a comparative example without the addition of copper sulfate aqueous solution, conductive furnace carbon black, and acetylene black.

The results in Table 2 show that the conductive carbon black of the present invention, in which metallic copper is microdispersed and immobilized in carbon black, can provide high conductivity with a small blending ratio. Further, due to such a small blending ratio, the decrease in mechanical strength can be ignored, and it is possible to have physical properties that harmonize conductivity and mechanical strength.

In addition, Run! '! Run t4h 1 and N14 on x 7 and ff1lo carbon black respectively
After adding fine powder of metallic copper of 44μ or less to carbon black and thoroughly mixing it so as to have the same mixing behavior as in Example 1, it was blended with high-density polyethylene in the same manner as in Example 1, and the volume resistivity was measured. The results were 17 and lOΩ・
It was α. That is, it is difficult to impart the high degree of conductivity shown in the present invention by simply mechanically mixing and dispersing fine powder of metallic steel in carbon black.

Example 2 35 parts by weight of carbon black and 10 parts by weight of high density polyethylene
Table 3 shows the results of measuring volume resistivity and tensile strength after blending in the same manner as in Example 1 except that 0 part by weight was blended.

From the results in Table 5, it is clear that when a large amount of the conductive carbon black of the present invention is blended, the conductivity is significantly improved. However, a decrease in mechanical strength and processability is observed with a high blending ratio.

Note that silver nitrate aqueous solution (i11 degrees 0
．． 2%) using the same method as in Example 1, the results showed the same tendency as the effect of the previous example, and it was confirmed that the conductivity imparting effect was further improved.

As is clear from the above examples, the conductive carbon black of the present invention can provide a high degree of conductivity with a small amount of compounding, and as a result, the decrease in mechanical strength can be significantly reduced. It has the advantage that the black can be easily dispersed and deterioration of workability such as wire crosstalk and moldability can be prevented.

Patent applicant: Tokai Carbon Co., Ltd. Agent: Patent Attorney Masaya Takahata

Claims (1)

[Claims] In a carbon black production method in which hydrocarbon feedstock oil is injected into a high-temperature combustion gas stream to cause a thermal decomposition reaction and to be converted into carbon black, a water-soluble copper compound and/or silver compound is added to the carbon black production zone. A method for producing conductive carbon black, which comprises adding an aqueous solution.