Halogen-free high-gloss black pigment and preparation method thereof

Abstract

The present invention relates to the field of pigments, and more specifically to a halogen-free, high-gloss black pigment and a preparation method thereof. The preparation method comprises the following steps: Step 1, preparing activated cobalt oxide; Step 2, preparing thiolated cobalt oxide; Step 3, preparing surface-modified cobalt oxide; and Step 4, preparing a halogen-free, high-gloss black pigment. The black pigment prepared by the present invention combines the advantages of inorganic and organic pigments, and has better dispersibility and brightness than conventional inorganic pigments. Compared with conventional organic pigments, it not only does not contain halogens but also has stronger light resistance.

Description

Technical Field

[0001] The present invention relates to the field of pigments, and in particular to a halogen-free high-gloss black pigment and a preparation method thereof. Background Art

[0002] With the development of society, people pay more and more attention to the decoration of buildings. Homes, offices and entertainment places are decorated with a large number of architectural decorative paints, wallpapers and decorative panels to reflect their style. Various colors of ink are printed on the wallpaper to form decorative wallpaper.

[0003] During the ink production process, pigments significantly impact not only the ink's appearance but also its printing quality. Commonly used pigments in inks include inorganic and organic pigments. Inorganic pigments are relatively simple to produce, inexpensive, and offer good mechanical strength and hiding power. However, they also suffer from issues such as a dark, less vibrant color, poor dispersibility, and an incomplete color spectrum. Organic pigments, on the other hand, offer not only good dispersibility but also vibrant colors and a wide variety of varieties, allowing for the production of a wide variety of colors. However, organic pigments are more susceptible to fading or discoloration when exposed to harsh conditions for a long time. Therefore, organic pigments often contain certain halogens. The addition of halogens can act as antioxidants, improve light stability, and reduce the risk of aging.

[0004] While the addition of halogens to pigments used in inks can improve ink performance, it can also create environmental issues. For example, the combustion process produces harmful halogenated substances, which pollute and harm the environment. Therefore, the development and use of pigments that do not contain halogen elements will become a trend in the future pigment market. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a halogen-free high-gloss black pigment and a preparation method thereof.

[0006] The purpose of the present invention is achieved by adopting the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a halogen-free high-gloss black pigment, comprising the following steps:

[0008] Step 1: Surface activation treatment of cobalt oxide particles in an alkaline solution to obtain activated cobalt oxide;

[0009] Step 2: treating the activated cobalt oxide with a coupling agent KH-580 to obtain thiolated cobalt oxide;

[0010] Step 3: Mixing mercaptolated cobalt oxide and 4-vinylaniline in a solvent and reacting them under the action of a photoinitiator to obtain surface-modified cobalt oxide;

[0011] In the fourth step, the surface-modified cobalt oxide and bisphenol A diglycidyl ether are mixed in anhydrous ethanol and subjected to a temperature-raising reaction treatment to obtain a halogen-free high-gloss black pigment.

[0012] Preferably, in the first step, the purity of the cobalt oxide particles is higher than 99%, and the particle size is 10±2 μm.

[0013] Preferably, in the first step, the surface activation treatment process includes:

[0014] The cobalt oxide particles are immersed in a sodium hydroxide solution and stirred at room temperature for 2-6 hours at a stirring speed of 200-300 r / min. After the stirring is completed, the precipitate is centrifuged and washed with water until the washing liquid is neutral. After drying, activated cobalt oxide is obtained.

[0015] Preferably, in the surface activation treatment process in step 1, the mass fraction of sodium hydroxide is 10%-20%, and the mass volume ratio of cobalt oxide particles to sodium hydroxide solution is 1g:(10-20)mL.

[0016] Preferably, in the second step, the preparation process of mercaptolated cobalt oxide includes:

[0017] Dissolve the coupling agent KH-580 in ethanol, add the activated cobalt oxide, mix evenly with ultrasound, and then reflux at 65-75°C for 6-12 hours. After the reflux is completed, centrifuge to obtain the precipitate, wash it with water three times, and vacuum dry it to obtain thiolated cobalt oxide.

[0018] Preferably, in the second step, the mass volume ratio of the activated cobalt oxide, coupling agent KH-580 and ethanol is 1 g: (0.1-0.5) g: (10-20) mL.

[0019] Preferably, in the third step, the preparation process of the surface-modified cobalt oxide includes:

[0020] The thiolated cobalt oxide and N-methylpyrrolidone are mixed, ultrasonically dispersed at room temperature, 4-vinylaniline is added, and a photoinitiator is added at the same time. The mixture is stirred under ultraviolet light for 0.8-1.6 hours. After the reaction is completed, the precipitate is collected by centrifugation, washed three times with alcohol, and then dried to obtain surface-modified cobalt oxide.

[0021] Preferably, in the third step, the mass volume ratio of mercaptolated cobalt oxide, 4-vinylaniline and N-methylpyrrolidone is 1 g: (0.23-0.46) g: (15-25) mL.

[0022] Preferably, in step 3, the photoinitiator is one of benzoin methyl ether (BME), benzoin ethyl ether (BEE), and benzoin butyl ether (BBE), and the amount of the photoinitiator added is 3% to 9% of the mass of 4-vinylaniline.

[0023] Preferably, in step 3, the intensity of the ultraviolet light is 200-300 mW / cm 2 , the wavelength is 200-400nm, preferably 365nm.

[0024] Preferably, in the fourth step, the temperature-raising reaction treatment process includes:

[0025] The surface-modified cobalt oxide and anhydrous ethanol are mixed and ultrasonically dispersed uniformly. The temperature is raised to 70-80°C under the condition of a reflux condenser. Bisphenol A diglycidyl ether (BADGE) is added dropwise. After the addition is completed, the mixture is kept warm and stirred for 2-3 hours. The precipitate is collected by centrifugation, vacuum-dried, and ground through a 200-mesh sieve to obtain a halogen-free high-gloss black pigment.

[0026] Preferably, in the fourth step, the mass volume ratio of the surface-modified cobalt oxide, bisphenol A diglycidyl ether and anhydrous ethanol is 1 g: (0.57-1.14) g: (15-25) mL.

[0027] In a second aspect, the present invention provides a halogen-free high-gloss black pigment prepared by the above-mentioned preparation method.

[0028] The beneficial effects of the present invention are:

[0029] 1. The black pigment prepared by the present invention combines the advantages of inorganic and organic pigments. Compared with conventional inorganic pigments, it has better dispersibility and brightness. Compared with conventional organic pigments, it not only does not contain halogen, but also has stronger light resistance.

[0030] 2. The present invention uses black-gray hexagonal cobalt oxide powder as a basic raw material, activates and thiol-modifies its surface in sequence to obtain thiol-modified cobalt oxide; then uses 4-vinylaniline to participate in the reaction to obtain cobalt oxide particles containing aniline groups on the surface; then, it undergoes an epoxy-amino combination reaction with bisphenol A diglycidyl ether to finally obtain the desired black pigment.

[0031] 3. During the preparation of surface-modified cobalt oxide, a thiol-alkenyl click chemistry reaction between the thiolated cobalt oxide and 4-vinylaniline occurs, anchoring aniline groups to the surface of the cobalt oxide and simultaneously introducing thioether groups. In a subsequent step, the aniline groups cross-link with the epoxy groups in bisphenol A diglycidyl ether, further introducing bisphenol A groups. Subsequent testing revealed that the black pigment prepared by this invention exhibits excellent dispersibility, brightness, and light resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0033] Figure 1 is a SEM schematic diagram of the halogen-free high-gloss black pigment prepared in Example 1 of the present invention;

[0034] Figure 2 Schematic diagrams of the black pigments of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention; wherein, (a) Example 1, (b) Comparative Example 1, and (c) Comparative Example 2. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the present invention.

[0036] In order to better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0037] The present invention will be further described below with reference to the following examples.

[0038] Example 1

[0039] A halogen-free high-gloss black pigment, the preparation method of which comprises the following steps:

[0040] In the first step, cobalt oxide (CoO) particles with a purity greater than 99% and a particle size of 10±2 μm were immersed in a 15 wt% sodium hydroxide solution at a mass volume ratio of 1 g of cobalt oxide particles to the sodium hydroxide solution of 15 mL. The mixture was stirred at room temperature for 4 hours at a stirring speed of 250 rpm. After stirring, the precipitate was centrifuged and washed with water until the washing solution was neutral. The precipitate was then vacuum dried to obtain activated cobalt oxide.

[0041] Step 2: Dissolve the coupling agent KH-580 in ethanol, add the activated cobalt oxide, and mix them in a mass-to-volume ratio of 1 g:0.3 g:15 mL of the activated cobalt oxide, coupling agent KH-580, and ethanol. Ultrasonication is then performed to homogenize the mixture, followed by refluxing at 70° C. for 9 h. After the reflux, the precipitate is collected by centrifugation, washed three times with water, and dried in vacuo to obtain the thiolated cobalt oxide.

[0042] In the third step, the mercapto-cobalt oxide and N-methyl pyrrolidone were mixed and ultrasonically dispersed at room temperature. Then, 4-vinyl aniline was added. The mass volume ratio of mercapto-cobalt oxide, 4-vinyl aniline and N-methyl pyrrolidone was 1 g:0.34 g:20 mL. At the same time, a photoinitiator, benzoin ethyl ether (BEE), was added in an amount of 6% of the mass of 4-vinyl aniline. Then, the photoinitiator was irradiated at a wavelength of 365 nm and an intensity of 250 mW / cm 2 The mixture was stirred under ultraviolet light for 1.2 hours. After the reaction was completed, the precipitate was collected by centrifugation, washed three times with alcohol, and then dried to obtain surface-modified cobalt oxide.

[0043] In the fourth step, the surface-modified cobalt oxide and anhydrous ethanol are mixed and uniformly dispersed by ultrasonication. The temperature is raised to 75°C under the condition of a reflux condenser, and bisphenol A diglycidyl ether (BADGE) is added dropwise. The mass volume ratio of surface-modified cobalt oxide, bisphenol A diglycidyl ether and anhydrous ethanol is 1g:0.86g:20mL. After the addition is completed, the mixture is kept warm and stirred for 2.5 hours, and the precipitate is collected by centrifugation, dried in vacuum, and ground through a 200-mesh sieve to obtain a halogen-free high-gloss black pigment.

[0044] Example 2

[0045] A halogen-free high-gloss black pigment, the preparation method of which comprises the following steps:

[0046] In the first step, cobalt oxide particles with a purity greater than 99% and a particle size of 10±2 μm were immersed in a 10 wt% sodium hydroxide solution at a mass volume ratio of 1 g of cobalt oxide particles to the sodium hydroxide solution of 10 mL. The mixture was stirred at room temperature for 2 hours at a stirring speed of 200 rpm. After stirring, the precipitate was centrifuged and washed with water until the washing solution was neutral. After drying, the activated cobalt oxide was obtained.

[0047] Step 2: Dissolve the coupling agent KH-580 in ethanol, add the activated cobalt oxide, and mix them in a mass-to-volume ratio of 1 g:0.1 g:10 mL of the activated cobalt oxide, coupling agent KH-580, and ethanol. Ultrasonication is then performed to homogenize the mixture, followed by refluxing at 65° C. for 6 h. After the reflux, the precipitate is collected by centrifugation, washed three times with water, and dried in vacuo to obtain the thiolated cobalt oxide.

[0048] Step 3: The mercapto-cobalt oxide and N-methyl pyrrolidone were mixed and ultrasonically dispersed at room temperature. 4-vinyl aniline was then added. The mass volume ratio of mercapto-cobalt oxide, 4-vinyl aniline and N-methyl pyrrolidone was 1 g:0.23 g:15 mL. At the same time, benzoin methyl ether (BME), a photoinitiator, was added in an amount of 3% of the mass of 4-vinyl aniline. The photoinitiator was then irradiated at a wavelength of 365 nm and an intensity of 200 mW / cm 2 The mixture was stirred under ultraviolet light for 0.8 h. After the reaction was completed, the precipitate was collected by centrifugation, washed three times with alcohol, and then dried to obtain surface-modified cobalt oxide.

[0049] In the fourth step, the surface-modified cobalt oxide and anhydrous ethanol are mixed and uniformly dispersed by ultrasonication. The temperature is raised to 70°C under the condition of a reflux condenser, and bisphenol A diglycidyl ether (BADGE) is added dropwise. The mass volume ratio of the surface-modified cobalt oxide, bisphenol A diglycidyl ether and anhydrous ethanol is 1g:0.57g:15mL. After the addition is completed, the mixture is kept warm and stirred for 2 hours, and the precipitate is collected by centrifugation, dried in vacuum, and ground through a 200-mesh sieve to obtain a halogen-free high-gloss black pigment.

[0050] Example 3

[0051] A halogen-free high-gloss black pigment, the preparation method of which comprises the following steps:

[0052] In the first step, cobalt oxide particles with a purity greater than 99% and a particle size of 10±2 μm are immersed in a 20 wt% sodium hydroxide solution at a mass volume ratio of 1 g of cobalt oxide particles to the sodium hydroxide solution of 20 mL. The mixture is stirred at room temperature for 6 hours at a stirring speed of 300 rpm. After stirring, the precipitate is centrifuged and washed with water until the washing solution is neutral. After drying, the activated cobalt oxide is obtained.

[0053] Step 2: Dissolve the coupling agent KH-580 in ethanol, add the activated cobalt oxide, and mix them in a mass-to-volume ratio of 1 g:0.5 g:20 mL of the activated cobalt oxide, coupling agent KH-580, and ethanol. Ultrasonication is then performed to homogenize the mixture, followed by refluxing at 75° C. for 12 h. After the reflux, the precipitate is collected by centrifugation, washed three times with water, and dried in vacuo to obtain the thiolated cobalt oxide.

[0054] Step 3: The mercapto-cobalt oxide and N-methyl pyrrolidone were mixed and ultrasonically dispersed at room temperature. 4-vinyl aniline was then added. The mass volume ratio of mercapto-cobalt oxide, 4-vinyl aniline and N-methyl pyrrolidone was 1 g:0.46 g:25 mL. At the same time, a photoinitiator, benzoin butyl ether (BBE), was added in an amount of 9% of the mass of 4-vinyl aniline. The photoinitiator was then irradiated at a wavelength of 365 nm and an intensity of 300 mW / cm 2 The mixture was stirred under ultraviolet light for 1.6 hours. After the reaction was completed, the precipitate was collected by centrifugation, washed three times with alcohol, and then dried to obtain surface-modified cobalt oxide.

[0055] In the fourth step, the surface-modified cobalt oxide and anhydrous ethanol are mixed and uniformly dispersed by ultrasonication. The temperature is raised to 80°C under the condition of a reflux condenser, and bisphenol A diglycidyl ether (BADGE) is added dropwise. The mass volume ratio of the surface-modified cobalt oxide, bisphenol A diglycidyl ether and anhydrous ethanol is 1g:1.14g:25mL. After the addition is completed, the mixture is kept warm and stirred for 3 hours, and the precipitate is collected by centrifugation, dried in vacuum, and ground through a 200-mesh sieve to obtain a halogen-free high-gloss black pigment.

[0056] Comparative Example 1

[0057] A black pigment is selected from the commercially available inorganic pigment cobalt black (Pigment Black 27).

[0058] Comparative Example 2

[0059] A black pigment is selected from the organic pigment aniline black PBK1 sold on the market.

[0060] Experimental testing

[0061] The performance of the black pigments of Example 1 and Comparative Examples 1-2 is compared. The results are shown in Table 1. The chromaticity in Table 1 is measured by a colorimeter to obtain its L * a * b * value; among them, L * The value represents the brightness of the material, the higher the value, the brighter it is; a * The value represents the red-green deviation, b * The color difference ΔE in Table 1 represents the change in color before and after 168 hours of exposure to an arc lamp, which is used to determine the light resistance of the pigment. The test is based on the ASTM D4303-03 standard and the calculation formula is ΔE = [(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ]1 / 2, the smaller the color difference value △E, the better the light fastness performance.

[0062] Table 1 Performance of different black pigments

[0063]

[0064] It can be seen from Table 1 that the black pigment prepared in Example 1 of the present invention not only does not contain halogen, but also has relatively high brightness and good light resistance.

[0065] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a halogen-free high-gloss black pigment, characterized in that: The following steps are involved: Step 1: Surface activation treatment of cobalt oxide particles in an alkaline solution to obtain activated cobalt oxide; Step 2: The activated cobalt oxide is treated with coupling agent KH-580 to obtain thiolated cobalt oxide; Step 3: Mixing mercapto-cobalt oxide and 4-vinylaniline in a solvent and reacting them under the action of a photoinitiator to obtain surface-modified cobalt oxide; Step 4: mixing the surface-modified cobalt oxide and bisphenol A diglycidyl ether in anhydrous ethanol and subjecting them to a temperature-raising reaction to obtain a halogen-free high-gloss black pigment; In the first step, the surface activation process includes: The cobalt oxide particles are immersed in a sodium hydroxide solution and stirred at room temperature for 2-6 hours at a stirring speed of 200-300 r / min. After the stirring is completed, the precipitate is centrifuged and washed with water until the washing liquid is neutral. After drying, activated cobalt oxide is obtained.

2. The method for preparing a halogen-free high-gloss black pigment according to claim 1, characterized in that: In the surface activation treatment process in step 1, the mass fraction of sodium hydroxide is 10%-20%, and the mass volume ratio of cobalt oxide particles to sodium hydroxide solution is 1g:(10-20)mL.

3. The method for preparing a halogen-free high-gloss black pigment according to claim 1, characterized in that: In the second step, the preparation process of mercaptolated cobalt oxide includes: Dissolve the coupling agent KH-580 in ethanol, add the activated cobalt oxide, mix evenly with ultrasound, and then reflux at 65-75°C for 6-12 hours. After the reflux is completed, centrifuge to obtain the precipitate, wash it with water three times, and vacuum dry it to obtain thiolated cobalt oxide.

4. The method for preparing a halogen-free high-gloss black pigment according to claim 3, characterized in that: In the second step, the mass volume ratio of the activated cobalt oxide, coupling agent KH-580 and ethanol is 1 g: (0.1-0.5) g: (10-20) mL.

5. The method for preparing a halogen-free high-gloss black pigment according to claim 1, characterized in that: In the third step, the preparation process of surface-modified cobalt oxide includes: The thiolated cobalt oxide and N-methylpyrrolidone are mixed, ultrasonically dispersed at room temperature, 4-vinylaniline is added, and a photoinitiator is added at the same time. The mixture is stirred under ultraviolet light for 0.8-1.6 hours. After the reaction is completed, the precipitate is collected by centrifugation, washed three times with alcohol, and then dried to obtain surface-modified cobalt oxide.

6. The method for preparing a halogen-free high-gloss black pigment according to claim 5, characterized in that: In the third step, the mass volume ratio of mercaptolated cobalt oxide, 4-vinylaniline and N-methylpyrrolidone is 1 g: (0.23-0.46) g: (15-25) mL.

7. The method for preparing a halogen-free high-gloss black pigment according to claim 1, characterized in that: In the fourth step, the process of temperature-raising reaction treatment includes: The surface-modified cobalt oxide and anhydrous ethanol are mixed and uniformly dispersed by ultrasonication. The temperature is raised to 70-80°C under the condition of a reflux condenser. Bisphenol A diglycidyl ether is added dropwise. After the addition is completed, the mixture is kept warm and stirred for 2-3 hours. The precipitate is collected by centrifugation, vacuum-dried, and ground through a 200-mesh sieve to obtain a halogen-free high-gloss black pigment.

8. The method for preparing a halogen-free high-gloss black pigment according to claim 7, characterized in that: In the fourth step, the mass volume ratio of the surface-modified cobalt oxide, bisphenol A diglycidyl ether and anhydrous ethanol is 1 g: (0.57-1.14) g: (15-25) mL.

9. A halogen-free high-gloss black pigment, characterized in that: The preparation method according to claim 1 is used for preparation.

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