CS232289B1 - Special soot - Google Patents

Abstract

The invention relates to special carbon blacks prepared from aqueous suspensions of carbon black microparticles by palletizing with hydrocarbon solvents and shaped into spherical granules, or prepared in the form of a powder. Due to their physical properties, special carbon blacks have extensive uses as an additive or filler for plastics, rubbers, paints, printing inks, etc., or as a sorption or filtration material, or as a catalyst for special oxidation reactions, or in the field of preparing new types of plastic substances suitable for products made of plastics and elastomers with antistatic treatment or for the preparation of non-metallic conductive materials. The addition of special carbon blacks achieves high quality of new plastics, rubbers and varnishes. The use of special carbon blacks in sorption, filtration and catalytic processes, especially in the field of wastewater treatment, achieves a high degree of purification of these waters.

Description

The invention relates to special carbon blacks prepared from aqueous suspensions of carbon black microparticles by pelletization with hydrocarbon solvents. Special carbon blacks formed into spheres of 0.1 to 5 mm in size, or in powder form, are used as an additive or filler in plastics, rubbers, paints, varnishes, etc., as a coloring agent or as an additive for modifying the conductivity properties of basic materials.

Aqueous suspensions of homogeneously dispersed carbon black microparticles are generally obtained by washing carbon black from gas streams formed by partial oxidation of carbon-containing raw materials, e.g. during gasification of petroleum and tar raw materials. The product of gasification of hydrocarbon fractions is producer gas, which is a raw material for the production of technical hydrogen and synthesis gas.

During partial oxidation of the gasified raw material, a part of it decomposes down to elemental carbon, which is carried away from the gasification space by the stream of produced gas. Due to the temperatures in the gasification space, the carbon formed is present in the form of soot, which is one of the types of so-called microcrystalline carbon. Soot microparticles are removed from the gas streams by washing with water under increased pressure. The resulting soot suspension in water is freed from soot by pelletizing it with the gasified raw material, and the isolated soot containing the gasified raw material is disposed of by incineration.

To adjust the conductivity properties of plastics and elastomers, acetylene carbon blacks are still mainly used, which are produced by thermal decomposition at temperatures around 800 ^° C. The decomposition of acetylene is strongly exothermic and the released heat maintains the course of pyrolysis without the addition of external heat. Acetylene carbon blacks have a mean particle diameter of 40 to 50 nm, a BET surface area in the range of 2-1 3-1 to 200 m .g , an oil number of 3 to 4 cm.g and a very low ash content of about 0.1%. To reduce the surface electrical resistance of plastic materials and rubbers to values below 1.10^ Ohms, 30 to 60 parts of carbon black per 100 parts of the base material must be added. However, this addition significantly worsens the mechanical properties of the new material compared to the original plastic.

As a coloring additive or filler for plastics, rubbers, etc., retort and channel carbon blacks, or even acetylene carbon blacks, are still mainly used. Oil retort carbon blacks are produced by burning aromatic fractions in retort furnaces. Oil retort carbon blacks have a mean particle diameter of 40 to 50 nm, a BET specific surface area of 80 to 150 m ² .g ^-1 and an oil number of 0.8 to 1.5 ml.g ^-1 . The ash content of these carbon blacks ranges from 0.1 to 1.0%, the residual oxygen content is 0.5 to 1.0% and the content of carcinogenic substances reaches up to 50 ppm in some types of carbon blacks.

Channel carbon black is produced by burning gaseous hydrocarbons, most often natural gas, in special furnaces with a steel insert, on which the resulting soot is collected. The soot collected on the insert is removed mechanically using scrapers. Channel carbon black has an average particle diameter in the range of 10 to 30 nm. The specific BET surface area ae ranges from 100

2-1 to 400 m .g , ash content in the range of 0.01 to 0.1 %, residual oxygen content in the range of 2.5 to 4 % and oil number ad 1.2 to 1.7 ml.g ^-1 . As a coloring additive for plastics, carbon black is used in an amount of 0.3 to 4 %; when carbon black is used as a filler for rubbers, the addition of carbon black ranges from 10 to 50 parts per 100 parts of raw material.

It has now been found and experimentally verified that by appropriately controlling the technological regime of partial oxidation of petroleum and tar raw materials, special carbon blacks are obtained that have a wide range of uses.

Special carbon blacks prepared from aqueous suspensions of carbon black particles by pelletization with hydrocarbon solvents, in particular from aqueous suspensions of carbon black formed during the gasification process of petroleum and tar raw materials in the presence of an oxygen-vapor mixture at temperatures of 1,350 to 1,430 °C and a pressure of 3 to 3.6 bar in the form of granules with a diameter of 0.1 to 5 mm, or in the form of dust, are characterized according to the invention in that the shaped carbon black granules and carbon black in the form of dust are formed from basic particles, the average size of which is in the range of 1 to 5 nm, while their porous structure is formed by free agglomeration of primary particles or secondary clusters with mechanical cohesion determined on the basis of the strength of the granules, which does not exceed 1.5 N per shaped particle, and an iodine number in the range of 800 to 1,500 mgJ.g ¹ and/or a specific surface determined by nitrogen adsorption in the range 800 to

2-1

250 m .g , a dibutyl phthalate absorption value determined on an absorptometer higher than 300 ml of dibutyl phthalate per 100 g of carbon black, an active specific surface determined by adsorption of cetyltrimethylammonium bromide in the range of 450 to 800 m .g , an ash content lower than 1.5 56, a moisture content lower than 1.2%, a residual hydrocarbon content determined by extraction of carbon disulfide lower than 0.7%, a sulfur content lower than 0.95 56, mechanical impurities determined as a residue on a 0.044 mm mesh in an amount of not more than 0.08% and a content of condensed aromatic hydrocarbons with carcinogenic effects below 1 ppm.

These special carbon blacks, characterized by the above physical properties, method of formation and preparation, have extensive use as an additive or filler for plastics, rubbers, paints, printing inks, etc. or as a sorption or filtration material, or as a catalyst for special oxidation reactions, or in the field of preparing new types of plastic substances suitable for products made of plastics and elastomers with antistatic treatment or for the preparation of non-metallic conductive materials.

When using the special carbon black according to the invention as a filler in the coloring of plastics, plastics with higher utility properties are obtained than when using conventional types of carbon black; in the field of rubber preparation, the use of carbon black according to the invention provides new types of highly tough rubbers. When using the special carbon black as an additive for the treatment of antistatic and conductive plastics, rubbers and varnishes, comparable electrical properties are achieved at a significantly lower dosage than with other types of carbon black, while the mechanical properties of a polymer with the addition of carbon black according to the invention are better than with a polymer with the addition of, for example, semiconducting acetylene carbon black. Conductive plastics can be prepared by adding the special carbon black according to the invention, while the addition of semiconducting acetylene carbon black does not achieve a specific internal plastic lower than 1 Ohm.cm.

The invention is further illustrated in the following examples.

Example.

The special carbon black according to the invention, which is characterized by a specific surface determined by 2-1 -1 nitrogen adsorption of 908 m .g , an iodine number of 964 mgJ.g ”, an active surface determined by ad2-1 sorption of cetyltrimethylammonium bromide of 615 m .g , a dibutyl phthalate absorption value determined on an absorptometer of 404 ml dibutyl phthalate/100 g and has a mineral ash-forming substance content of 0.65%, a sulfur content of 0.49 56, a moisture content of 0.32 56, a residual hydrocarbon content determined by extraction with carbon disulfide of 0.43% and a mechanical impurity content determined as a residue on a 0.044 mm mesh of 0.0043%, were added together with a stabilizer to high-density polyethylene. The mixture was processed and the obtained type of plastic with antistatic treatment was subjected to testing electrical and mechanical properties. The stabilizer content was constant and amounted to .0.2 56. The addition of carbon black was varied in the range of 6 to 12%. The original polymer is also shown in the table for comparison. The mean size of the basic particles was 2.65 nm and the carbon black was shaped into granules of 1 to 2 mm. The mean mechanical strength of the particles of the 1.6 to 2 mm fraction was 0.35 N per particle. Hydrocarbons with carcinogenic effects were not found in the carbon black.

T a b l e 1 k a 1

carbon black {% by weight) resistivity (Ohm.cm) tensile strength (MPa) ductility (56) 0 10 ¹⁶ 28 1,100 6 2.10 ⁷ 27.2 570 8 148.5 27.9 480 10 29.8 27.1 123 12 10.5 28.7 44

Example 2

The special carbon black according to the invention, characterized in Example 1, was used to prepare a semiconducting film made of plasticized PVC. The mechanical and electrical properties of the film are given in Table 2.

Table 2

Soot concentration (% by weight) properties 8 ,0 15 tensile strength (MPa) 12.6 12.2 11.1 elasticity (%) 423 381 299 hardness (°Sh) 83 86 91 surface electrical resistance (Ohm) 1,650 232 12.4

Example 3

The special carbon blacks according to the invention, characterized in Example 1, were added to a rubber mixture in order to prepare special conductive rubbers. The effect of the addition of the special carbon blacks on the quality of the material is shown in the following table:

Table 3

Carbon dioxide (part/100 parts rubber) strength limit (MPa) ductility (*) hardness of the material (°Sh) internal resistance ((Mim. cm) 0 7.8 63 10 ¹⁵ 5 13.6 860 69 10 ⁸ 8 18.2 960 68 10 ⁶ 10 15.5 850 70 3.10 ⁵ 15 16.7 820 75 260 20 14.2 740 79 224 25 ’3.8 600 83 182 30 12.9 400 86 141 40 5.3 - 87 8.1

Example 4

Special carbon blacks according to the invention, characterized by a specific surface area determined by 2-1-1 nitrogen adsorption of 1,087 a.g, an iodine number of 1,124 mgJ.g, a dibutyl phthalate absorption value determined on an absorptometer of 445 ml dibutyl phthalate/100 g, an active surface area determined by cetyltrimethylammonium bromide adsorption of 693 m^.g ^- ', having a sulfur content of 0.33%, a moisture content of 0.86% and a residual hydrocarbon content determined by CS ₂ extraction of 0.29%, an ash content of 0.67% and a residue on a 0.044 mm mesh, 0.0020%, were used to prepare conductive plasticized PVC plastics. The dependence of carbon black concentration on specific resistance is given in Table 4. Carbon black with an average particle size of 2.41 nm, shaped into granules of 0.7 to 3 mm in size, was used for the preparation, while the mechanical strength of particles of the 2.5 to 3 mm fraction did not exceed 1.12 N/particle. The content of hydrocarbons with carcinogenic effects was 0.01 ppm.

Table 4

Sase (» ha) 0 10 20 25 30 resistivity (Oha.cm) 10 ¹⁴ 3.1.10 ³ 74 1.8 0.5

Example 5

The special carbon black according to the invention, characterized in Example 4, was used for the preparation of an electrostatically conductive varnish intended for coating a PVC product. The dependence of the carbon black concentration on the surface resistance of the lat is given in the following table.

Table 5

Carbon black (% wt) 10 12 15 20 40 50 surface resistance (Ohm)

Example 6

2,1.10'

1: ^9.10-3

1:1.10· ³

250

The special carbon black according to the invention, characterized in Example 1, was used as a coloring additive to linear polyethylene in an amount of 2.4%. The mixture of stabilizing additives, linear polyethylene and coloring additive was homogenized to a melt, from which a black polymer granulate was prepared and used for products intended for contact with foodstuffs. For comparison, a granulate was prepared which contained as a coloring additive carbon black, characterized by a specific surface area of 184 m .g , an iodine number of 192 mgJ.g, a dibutyl phthalate absorption value of 132 ml dibutyl phthalate/100 g and had a moisture content of 1.1%, an ash content of 0.15% and a carcinogenic hydrocarbon content of 0.04 ppm. The evaluation of the stability of the polymer, which is carried out by measuring the induction period of thermooxidation, i.e. by measuring the length of the Sasov period until the start of oxygen adsorption at a given temperature, is given in Table S. 6. . The evaluation of the mechanical properties of the polymer was carried out by measuring the stress time of the produced sample of 5 test tubes for strength against internal overpressure at a temperature of 80 °C and a stress of 4.2 MPa, while from the sample of test tubes with carbon black according to the invention, the first tube burst after 470 hours of stress and the other tubes were undamaged after 1,290 hours of testing. In the comparative polymer, the first tube burst after .38 hours, the second after /3.0 hours and the third after 435 hours, when the test of mechanical properties was completed. The comparative polymer was prepared with the same content of stabilizing and coloring additives.

Table of induction period of thermooxidation

180 ⁵ C ,20 °C (min) (days)

Carbon black according to the invention 3.5 69

Comparative carbon black 226 56

Example 7

Styrene-butadiene rubber with added stabilizing and inhibiting additives was mixed with various types of carbon black and processed into a vulcanizate. The effect of the type of carbon black and its added amount on the conductivity and mechanical properties is shown in the following table.

Table 7

Type of soot soot concentration specific resistance tensile strength protainoet (part/100 parts rubber) (Ohm.cm) (MPa) (») special carbon black 5 1,3.10 ¹³ 9.1 600 according to the invention 10 9,2.10 ² 16.6 640 15 3,8.10 ² 21.7 650 25 2.5.10 ² 24.4 550

Table 7 continued

Type of soot carbon black concentration (parts/100 parts of rubber) resistivity (Ohm.cm) tensile strength (MPa) extensibility («) „ 13 acetylene 15 4,6.10 10, 1 540 soot 25 1,7.10 ¹³ 16.1 570 40 2,4.10 ⁶ 17.8 460 60 6.5.10 ² 21.2 390 conductive retort 15 8,2.10 ¹² 14.5 630 soot 25 5.5.10 ¹⁰ 22.3 680 40 1.5.10 ³ 24.0 640 60 2,6.10 ² 22.8 550 retort carbon black 60 5,6.10 ⁸ 21.7 300 Example 8 Linear polyethylene with addition the stabilizer was mixed with various types of soot and dust resin granulate for moldings with antistatic treatment. The influence of soot types and their concentration-

The effect on conductivity properties is given in Table 8.

Table 8 specific internal resistance (Ohm.cm)

Soot concentration («) special carbon black according to the invention acetylene carbon black conductive retort carbon black 0 2.10 ¹⁷ 6 680 - - 10 28.9 9.5.10 ¹⁶ 7.10 ¹⁶ 15 7.1 3.10 ¹⁶ 5.10 ⁵ 25 - 2.5.10 ³ 89

Example 9

Special carbon black according to the invention in the form of a powder with a grain size of 0.01 to 0.1 mm was used as a catalyst in the removal of HCN from wastewater. Waste water containing 156 mg HCN.l ^-1 was mixed with air and an aqueous suspension of carbon black, which was prepared by stirring the powder in water, and after a reaction time of 45 minutes, the HCN content in the wastewater was reduced to 2.5 mg.l ^-1 .

Example ,0

Special carbon black according to the invention, shaped into granules of 1 to 3 mm in size, was used as a sorption material in the purification of condensate contaminated with fuel oil. The inlet water contained 196 mg.l" ¹ of petroleum substances. In the purified water, after the passage of 2.9 m ³ of water per 1 kg of sorption material, the content of non-polar hydrocarbons was determined to be lower than 0.1 mg.1" ¹ and after the passage of another 2.5 m ³ of purified water/kg of sorption material, the content of non-polar hydrocarbons was lower than 1 mg.1 ¹ . The volumetric throughput of the sorption filter was 2.8 m ³ .m~ ³ .h" ¹ .

The efficiency of sorption purification using special carbon black according to the invention was compared with activated carbon with a surface area of 1,050 m .g , grain size of 1 mm using the same amount of contaminated water. The volumetric sieving was 3.2 m\m .h ^-1 and purified water with a content of 2.5 mg.l ^- ' of non-polar hydrocarbons was obtained after passing 1.5 m^ of purified water per 1 kg of activated carbon.

Claims (1)

SUBJECT OF THE INVENTION Special carbon black prepared from aqueous suspensions of carbon black particles by pelletizing with hydrocarbon solvents, in particular from aqueous suspensions of carbon black formed by the gasification process of petroleum and tar feedstocks in the presence of an oxygen-vapor mixture at temperatures of 1 350 ° C to 1 430 ° C and 3 to 3,6 MPa; in the form of granules with a diameter of 0.1 to 5 mm, possibly in the form of dust, characterized in that the shaped carbon black granules and the carbon black in the form of dust are formed from basic particles whose mean size is in the range 1 to 5 nm. formed by free agglomeration of primary particles or secondary agglomerates with mechanical cohesion determined on the basis of granule strength not exceeding 1.5 N per shaped particle, and an iodine value in the range of 800 to 1500 mgJ.ga/or 2-1 specific surface area determined by nitrogen adsorption in the range of 800 to 1 250 mg, with a dibutyl phthalate adsorption value determined on an absorptometer of greater than 300 ml of dibutyl phthalate per 100 g of carbon black, active surface area determined by adsorption of cetyltrimethyl ammonium bromide in the range 450 to 800 m ² .g ^-1 , ash content less than 1,5%, moisture content less than 1,2%, residual hydrocarbon content determined by extraction carbon disulfide of less than 0,7%, a sulfur content of less than 0,95%, of mechanical impurities determined as a residue on 0,044 mm sieves in an amount of not more than 0,08% containing condensed aromatic hydrocarbons with carcinogenic effects below 1 ppm.