A production process for controlling the true density of nano carbon black

Abstract

The present invention provides a production process for controlling the true density of nano carbon black. Through carboxylation modification of the surface of nano carbon black, surface carboxylated nano carbon black is prepared. Then, sodium silicate is deposited on its surface. The deposited sodium silicate on the surface reacts with the carboxyl groups to precipitate stable silica, which can block the internal pores of nano carbon black, so that when nano carbon black is applied in systems such as inks and rubbers, its true density can be reduced; while adsorbing a small amount of paraffin has an obvious effect on improving the stability of the true density of nano carbon black in water-based inks.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-carbon black modification, and more specifically, the present invention relates to a production process for controlling the true density of nano-carbon black. Background Art

[0002] Nano-carbon black has excellent coloring properties, weather resistance and chemical stability, and is rich in sources and low in price. It is an important reinforcing agent and coloring agent.

[0003] The density of nano-carbon black in the solid state is expressed as the bulk density or apparent density, generally in the range of 0.1 - 0.5 g / cm 3 ; when nano-carbon black is applied in systems such as inks and rubbers, due to reasons such as being infiltrated by the system, nano-carbon black exhibits a true density of about 1.8 g / cm 3 . This difference between the true density and the apparent density is mainly caused by the internal pores of nano-carbon black and the stacking voids of nano-carbon black.

[0004] The density of the rubber system is as low as about 0.9 g / cm 3 ; the density of the ink is closely related to the solvent used, generally in the range of 0.9 g / cm 3 - 1.2 g / cm 3 , and the density of the water-based ink is close to 1.0 g / cm 3 . Therefore, when nano-carbon black is applied in systems such as inks and rubbers, there is a large density difference between nano-carbon black and inks, rubbers, etc., making it prone to problems such as sedimentation. Summary of the Invention

[0005] The present invention provides a production process for controlling the true density of nano-carbon black. Through surface carboxylation modification of nano-carbon black, surface-carboxylated nano-carbon black is prepared, and then sodium silicate is deposited on its surface. The deposited sodium silicate on the surface reacts with the carboxyl groups to precipitate stable silicon oxide, which can block the internal pores of nano-carbon black, so that when nano-carbon black is applied in systems such as inks and rubbers, its true density is reduced; and adsorbing a small amount of paraffin has an obvious effect on improving the stability of the true density of nano-carbon black in water-based inks.

[0006] A production process for controlling the true density of nano-carbon black, the production process is specifically as follows:

[0007] (I) Surface carboxylation modification of nano-carbon black

[0008] (1) Disperse nano-carbon black in hydrogen peroxide with a mass fraction of 1% - 2% at 0.5 - 0.8 times the mass, heat to 60 - 70 °C, react for 30 - 50 min, and centrifuge to filter out the solid matter;

[0009] (2) Place the solid in a sealed reactor, heat it to 40 - 50 °C, start stirring, and then introduce pure ozone until the solid is completely dry to obtain surface - carboxylated nanocarbon black;

[0010] (II) Preparation of sodium silicate solution

[0011] (3) Take a certain amount of sodium silicate and dissolve it in hot water at 55 - 60 °C to make a saturated sodium silicate solution;

[0012] (III) Sealing nanocarbon black

[0013] (4) Disperse the surface - carboxylated nanocarbon black in a polar solvent with a mass 0.8 - 1.5 times that of the nanocarbon black, and cool it to 0 - 2 °C during dispersion to obtain a suspension;

[0014] (5) Slowly drop the suspension into the sodium silicate solution according to the volume ratio of suspension:sodium silicate solution of 1 - 2:1. Keep the sodium silicate solution warm, and finally filter out the solid, dry it to obtain sealed nanocarbon black.

[0015] Further, the particle size of the nanocarbon black is 50 - 200 nm.

[0016] Further, the modulus of the sodium silicate is 3.1 - 3.4.

[0017] Further, add paraffin with a mass of 0.1% - 0.5% of the solution mass to the saturated sodium silicate solution in step (3).

[0018] Further, the paraffin is paraffin No. 52 or paraffin No. 54.

[0019] Further, the polar solvent is methanol, ethanol or acetone.

[0020] The technical effects and advantages of the present invention:

[0021] 1. By surface - carboxylation modification of nanocarbon black, the present invention obtains surface - carboxylated nanocarbon black, and then deposits sodium silicate on its surface. The deposited sodium silicate reacts with the carboxyl group to precipitate stable silicon oxide, which can block the internal pores of the nanocarbon black. When the nanocarbon black is applied in systems such as inks and rubbers, its true density can be reduced;

[0022] 2. After adding a small amount of paraffin to the saturated sodium silicate solution, the stability of the true density of the nanocarbon black in water - based inks is significantly improved. Specific embodiments

[0023] Example 1

[0024] A production process for controlling the true density of nanocarbon black, and the specific production process is as follows:

[0025] (1) Carboxylation modification of nano carbon black surface

[0026] (1) Dispersed aqueous nano carbon black with a particle size of 100 nm in 0.6 times the mass of 1.2% hydrogen peroxide solution by mass, heated to 65 °C, reacted for 30 min, and the solid was filtered out by centrifugation;

[0027] (2) The solid was placed in a sealed reactor, heated to 40 °C, stirred, and then pure ozone was introduced until the solid was completely dried to obtain surface carboxylated nano carbon black;

[0028] (2) Preparation of sodium silicate solution

[0029] (3) A certain amount of sodium silicate with a modulus of 3.3 was dissolved in hot water at 60 °C, and then paraffin No. 54 accounting for 0.2% of the solution mass was added to make a saturated sodium silicate solution;

[0030] (3) Sealing nano carbon black

[0031] (4) The surface carboxylated nano carbon black was dispersed in 1.1 times the mass of ethanol, and cooled to 0 °C during dispersion to obtain a suspension;

[0032] (5) According to the volume ratio of suspension: sodium silicate solution of 1.5:1, the suspension was slowly added dropwise to the sodium silicate solution, and the sodium silicate solution was continuously kept warm. Finally, the solid was filtered out and dried to obtain sealed nano carbon black.

[0033] Comparative example 1

[0034] The nano carbon black with a particle size of 100 nm in Example 1 was used.

[0035] Comparative example 2

[0036] In step (3), paraffin was not added, and the other steps were the same as in Example 1.

[0037] In the laboratory, 500 g of sealed nano carbon black was produced according to the processes of Example 1 and Comparative example 2 respectively, and was tested and compared with the raw material nano carbon black (Comparative example 1) to test its true density and stability in water.

[0038] 1. Add 20 mL of water to a 50 mL graduated pipette with scale, then block the lower opening, add 20 g of the above carbon black from the upper opening, and then seal the upper opening. Then place it in an ultrasonic oscillator and shake for 30 min, and then read the volume to obtain the true density A. True density (g / cm 3 ) = 20 / increased volume (g / cm 3 )

[0039] 2. After standing for 1 month, observe again and read the volume to obtain the true density B.

[0040] Test <![CDATA[True density A (g / cm 3 )]]> <![CDATA[True density B (g / cm 3 )]]> Example 1 1.42 1.49 Comparative Example 1 1.75 1.83 Comparative Example 2 1.45 1.71

[0041] The above embodiments and comparative examples are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail through the above embodiments and comparative examples, those skilled in the art should understand that various changes can be made to it in terms of form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A production process for controlling the true density of nano carbon black, characterized in that: The specific production process is as follows: (I) Surface carboxylation modification of nano carbon black (1) Disperse nano carbon black in hydrogen peroxide solution with a mass fraction of 1%-2% and a mass 0.5-0.8 times that of nano carbon black, heat to 60-70 °C, react for 30-50 min, and centrifuge to filter out the solid matter; (2) Place the solid matter in a sealed reactor, heat to 40-50 °C, start stirring, and then introduce pure ozone until the solid matter is completely dried to obtain surface carboxylated nano carbon black; (II) Preparation of sodium silicate solution (3) Take a certain amount of sodium silicate, dissolve it in hot water at 55-60 °C, and add paraffin with a mass of 0.1%-0.5% of the solution mass to make a saturated sodium silicate solution; (III) Sealing nano carbon black (4) Disperse the surface carboxylated nano carbon black in a polar solvent with a mass 0.8-1.5 times that of nano carbon black, and cool to 0-2 °C during dispersion to obtain a suspension; (5) Slowly add the suspension to the sodium silicate solution according to the volume ratio of suspension:sodium silicate solution of 1-2:

1. Keep the sodium silicate solution warm, and finally filter out the solid matter and dry it to obtain sealed nano carbon black.

2. The production process for controlling the true density of nano carbon black according to claim 1, characterized in that: The particle size of the nano carbon black is 50-200 nm.

3. The production process for controlling the true density of nano carbon black according to claim 1, characterized in that: The modulus of the sodium silicate is 3.1-3.

4.

4. The production process for controlling the true density of nano carbon black according to claim 1, characterized in that: The paraffin is paraffin No. 52 or paraffin No.

54.

5. The production process for controlling the true density of nano carbon black according to claim 1, characterized in that: The polar solvent is methanol, ethanol or acetone.