A process for modifying hydrophobic carbon black into waterborne self-dispersible carbon black

Abstract

The present invention discloses a process for modifying hydrophobic carbon black into waterborne self-dispersible carbon black. By dispersing hydrophobic nano-carbon black in an alcohol-soluble urea solution and then subjecting it to spray high-temperature treatment, waterborne self-dispersible carbon black is obtained: an acidic environment for coupling with a waterborne coupling agent is formed by isocyanic acid obtained from the deamination of urea at high temperature, and after the biuret obtained from the condensation reaction of urea at high temperature is coupled with the hydrophobic nano-carbon black, excellent waterborne self-dispersible performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of nano carbon black modification. More specifically, the present invention relates to a process method for modifying hydrophobic carbon black into waterborne self-dispersible 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, making it one of the important colorants.

[0003] In the prior art, nano carbon black is widely used in fields such as rubber, plastics, inks, coatings, etc. To meet the usage requirements, nano carbon black can be classified into varieties such as waterborne nano carbon black and hydrophobic nano carbon black. Among them, the vast majority of nano carbon black belongs to hydrophobic nano carbon black, while there is a wide demand for waterborne nano carbon black in fields such as inks and coatings.

[0004] However, waterborne nano carbon black and hydrophobic nano carbon black generally cannot be mixed or used interchangeably. When nano carbon black is used in products such as environmentally friendly waterborne inks and waterborne coatings, hydrophilic nano carbon black needs to be admixed, otherwise it will lead to a mismatch between nano carbon black and the hydrophilic matrix material system of inks and coatings, resulting in difficulties in dispersing nano carbon black, serious agglomeration, sedimentation, etc.

[0005] Therefore, in these fields, there is an objective practical need to modify hydrophobic nano carbon black into waterborne nano carbon black. Summary of the Invention

[0006] The present invention provides a process method for modifying hydrophobic carbon black into waterborne self-dispersible carbon black. By dispersing hydrophobic nano carbon black in an alcohol-soluble urea solution and then subjecting it to spray high-temperature treatment, waterborne self-dispersible carbon black is obtained.

[0007] A process method for modifying hydrophobic carbon black into waterborne self-dispersible carbon black is as follows:

[0008] (1) Preparation of alcohol-soluble urea solution: Take a certain amount of ethanol, then add a waterborne coupling agent accounting for 1%-2% of the mass of ethanol, and at the same time add urea accounting for 3%-5% of the mass of ethanol, and disperse evenly to obtain an alcohol-soluble urea solution;

[0009] (2) Mix according to the mass ratio of hydrophobic nano carbon black: alcohol-soluble urea solution of 1:2-3, and after dispersing evenly, obtain material A;

[0010] (3) Dry material A by spray drying, and control the temperature of spray drying at 170°C - 180°C to obtain waterborne self-dispersible nano carbon black.

[0011] Furthermore, the volume fraction of the ethanol is 40%-60%.

[0012] Further, the aqueous coupling agent is an aqueous silane coupling agent or an aqueous titanate coupling agent.

[0013] The aqueous silane coupling agent is one or more of KH-460, KH-550, and KH-560.

[0014] The aqueous titanate coupling agent is QX-311W or QX-200S.

[0015] Further, the particle size of the hydrophobic nano carbon black is 20 nm - 100 nm.

[0016] Technical effects and advantages of the present invention:

[0017] 1. In the present invention, hydrophobic nano carbon black is dispersed in an alcohol-soluble urea solution, and then aqueous self-dispersible carbon black is prepared through spray high-temperature treatment: an acidic environment coupled by an aqueous coupling agent is formed by the isocyanic acid obtained by the deamination of urea at high temperature, and after the biuret obtained by the condensation reaction of urea at high temperature is coupled with the hydrophobic nano carbon black, excellent aqueous self-dispersibility is obtained;

[0018] 2. The present invention can modify and transform the remaining hydrophobic nano carbon black in production and the useless hydrophobic nano carbon black caused by the adjustment of the product system into aqueous self-dispersible nano carbon black, improving the material utilization rate and preventing waste. Specific embodiments

[0019] Example 1

[0020] A process for modifying hydrophobic carbon black into aqueous self-dispersible carbon black, and the process is as follows:

[0021] (1) Preparation of the alcohol-soluble urea solution: Take a certain amount of ethanol with a volume fraction of 50%, then add 1.5% by mass of the aqueous silane coupling agent KH-560 based on the mass of ethanol, and at the same time add 4% by mass of urea based on the mass of ethanol, and disperse evenly to obtain the alcohol-soluble urea solution;

[0022] (2) Mix according to the ratio of 40 nm hydrophobic nano carbon black: alcohol-soluble urea solution mass ratio of 1:2.2, and after dispersing evenly, obtain material A;

[0023] (3) Dry material A by spray drying, and control the temperature of spray drying at 175 °C to obtain aqueous self-dispersible nano carbon black.

[0024] Comparative Example 1

[0025] The unmodified 40 nm hydrophobic nano carbon black used in Example 1.

[0026] Comparative Example 2

[0027] The temperature of spray drying was controlled at 166 °C, and the remaining processes were the same as those in Example 1.

[0028] Comparative Example 3

[0029] The temperature of spray drying was controlled at 190 °C, and the remaining processes were the same as those in Example 1.

[0030] Comparative Example 4

[0031] An equal mass of 1% hydrogen peroxide solution was used to replace the alcohol-soluble urea solution, and surface-oxidized modified carbon black was prepared by the processes of steps (2) and (3) in Example 1.

[0032] A waterborne varnish was prepared with Corning 709Y waterborne thermosetting acrylic resin. 5% by mass of the carbon black prepared in the above examples and comparative examples was added to the above varnish. After being treated by the same sanding process, it was stored in an environment at 60 °C, and the stability time of the system was observed. The end point was when stratification occurred on the upper layer of the system, and the appearance was also observed.

[0033] Test System stability time (days) Appearance Example 1 >20 Uniform and stable Comparative Example 1 2 Sedimentation and agglomeration Comparative Example 2 2 Sedimentation and agglomeration Comparative Example 3 8 Sedimentation but no agglomeration Comparative Example 4 5 Sedimentation but no agglomeration

[0034] At the same time, conventional 40-nm waterborne nano-carbon black was tested in the above waterborne varnish. Its stability time was 7 days, and the waterborne nano-carbon black settled but did not agglomerate. The stability time of Example 1 exceeded 20 days, and there was no stratification on the upper layer on the 20th day.

[0035] Through the modification of the present invention, hydrophobic nano-carbon black can be transformed into waterborne self-dispersible carbon black, and its dispersion stability exceeds that of general waterborne nano-carbon black; while by oxidizing hydrophobic nano-carbon black with an oxidant to hydroxylate its surface, its dispersion stability is weaker than that of general waterborne nano-carbon black.

[0036] The above examples and comparative examples are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail through the above examples and comparative examples, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A process for modifying hydrophobic carbon black into waterborne self-dispersible carbon black, characterized in that: The specific process method is as follows: (1) Preparation of the alcohol-soluble urea solution: Take a certain amount of ethanol, then add a water-based coupling agent accounting for 1%-2% of the mass of ethanol, and at the same time add urea accounting for 3%-5% of the mass of ethanol, and disperse evenly to obtain the alcohol-soluble urea solution; The water-based coupling agent is a water-based silane coupling agent or a water-based titanate coupling agent. The water-based silane coupling agent is one or more of KH-460, KH-550, and KH-560. The water-based titanate coupling agent is QX-311W or QX-200S; (2) Mix in a ratio of hydrophobic nanocarbon black: alcohol-soluble urea solution mass ratio of 1:2-3, and after dispersing evenly, obtain material A; (3) Dry material A by spray drying, and control the temperature of spray drying at 170°C-180°C to obtain water-based self-dispersible nanocarbon black.

2. The process method for modifying hydrophobic carbon black into waterborne self-dispersible carbon black according to claim 1, characterized in that: The volume fraction of the ethanol is 40%-60%.

3. The process method for modifying hydrophobic carbon black into water-based self-dispersible carbon black according to claim 1 or 2, characterized in that: The particle size of the hydrophobic nanocarbon black is 20nm-100nm.