A scratch-resistant antibacterial matte black paint for plastic substrates, and a preparation method and application thereof

Abstract

This invention belongs to the field of coating technology, and relates to a scratch-resistant, antibacterial, matte black coating for use on plastic substrates, its preparation method, and its application. The coating comprises the following components by weight: 40-60 parts acrylic resin; 2-5 parts carbon black; 0-10 parts nano-modified lignin (not 0 parts); 1-10 parts nano-matte powder; 1-5 parts dispersant; 0.1-1 part leveling agent; 0.1-1 part anti-settling agent; and 5-30 parts solvent. Compared with existing technologies, this invention, by adding a small amount of nano-modified lignin to the formulation to prepare a matte black coating, when applied to the surface of plastic products, can effectively improve the scratch resistance of the paint film, provide highly effective antibacterial properties, and thus greatly extend the product's service life.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a scratch-resistant, antibacterial, matte black coating for use on plastic substrates, its preparation method, and its application. Background Technology

[0002] Plastics themselves have relatively limited color and texture options, and generally suffer from low hardness, susceptibility to scratches, and poor chemical resistance. Adding one or more layers of coating to the plastic surface can achieve a rich variety of colors, high / matte finishes, metallic textures, and unique tactile sensations, significantly increasing the product's added value. Simultaneously, the coating provides a robust protective layer, improving wear and scratch resistance, as well as antibacterial properties, extending the product's lifespan. This technology is widely used in laptops, home appliances, automotive interiors and exteriors, and medical devices.

[0003] Matte black paint is widely used in the industrial coatings field due to its unique low gloss and delicate texture. Traditional matte paints, especially those with a gloss level below 5°, have poor scratch resistance; even a slight scratch with a fingernail will leave a noticeable mark. Furthermore, the products used in these paints are often frequently touched by our hands, which inevitably leads to the accumulation of bacteria over time, and traditional matte black paints do not possess antibacterial properties. Summary of the Invention

[0004] In view of the shortcomings of existing matte black coatings, such as poor scratch resistance and poor antibacterial properties, this invention provides a scratch-resistant and antibacterial matte black coating for use on plastic substrates, as well as its preparation method and application.

[0005] The objective of this invention can be achieved through the following technical solutions: One objective of this invention is to provide a scratch-resistant, antibacterial, matte black coating for use on plastic substrates, comprising the following components in parts by weight: 40-60 parts of acrylic resin; 2-5 parts carbon black; 0-10 parts of nano-modified lignin, wherein 0 parts of nano-modified lignin are not included; 1-10 parts of nano matting powder; 1-5 parts dispersant; Leveling agent 0.1-1 part; Anti-settling agent 0.1-1 part; Solvent 5-30 parts.

[0006] Furthermore, the acrylic resin is a medium hydroxyl content, high TG point acrylic resin, preferably commercially available Hemings Chemical FS-2450F.

[0007] Furthermore, the carbon black is a high-pigment carbon black, selected from commercially available Evonik FW-200.

[0008] Furthermore, the preparation method of the nano-modified lignin is as follows: Take lignin, acetone and water, stir and mix, concentrate by rotary evaporation, cool and dry to obtain lignin colloidal spheres; disperse the lignin colloidal spheres in anhydrous ethanol, and disperse by ultrasonication to obtain lignin colloidal dispersion; Adjust the pH to acidic, add glutaraldehyde solution while stirring, and stop when dark brown powder precipitates. After the reaction is complete, centrifuge and wash the product multiple times, and dry to obtain nano-modified lignin.

[0009] Furthermore, the matting agent is nano-sized fumed silica with a particle size between 20-40nm, which provides the paint film with a silky, swan-like smooth feel, and is selected from commercially available Guangdong Slika FS-102.

[0010] Furthermore, the dispersant is a high molecular weight acrylic block copolymer, which improves pigment surface wetting and dispersion stability and enhances grinding efficiency, and is selected from commercially available EFKA-4310.

[0011] Furthermore, the leveling agent is a polyether-modified polydimethylsiloxane copolymer solution, which increases surface smoothness and scratch resistance by reducing the surface tension of the paint film, and is selected from commercially available BYK-306.

[0012] Furthermore, the anti-settling agent includes one of bentonite or fumed silica.

[0013] The second objective of this invention is a method for preparing a scratch-resistant, antibacterial, matte black coating for use on plastic substrates as described above, comprising the following steps: The dispersant and acrylic resin were added to the solvent and stirred at low speed for 10 minutes to obtain the first mixture; Carbon black, nano-modified lignin, and anti-settling agent are added to the first mixture under stirring, and the mixture is ground to a fineness of less than 10 μm to obtain the second mixture. Nano-matte powder and leveling agent are added to the second mixture under stirring. After dispersion and mixing, a scratch-resistant and antibacterial matte black coating is obtained.

[0014] The third objective of this invention is the application of a scratch-resistant, antibacterial, matte black coating as described above on plastic substrates, specifically for use on plastic substrates of consumer electronics, home appliances, automotive interior and exterior trim, and medical devices.

[0015] Compared with existing technologies, this invention creates a matte black coating by adding a small amount of nano-modified lignin to the formula. When applied to the surface of plastic products, it effectively improves the scratch resistance of the paint film, provides highly effective antibacterial properties, and thus greatly extends the product's service life. Lignin, as a renewable resource, not only meets green environmental protection requirements but is also inexpensive. After nano-modification, its rigid benzene ring structure effectively improves the hardness of the paint film, further enhancing scratch resistance. Simultaneously, it has an inhibitory effect on various microorganisms and fungi, exhibiting strong antibacterial properties. Furthermore, the large number of benzene rings and phenolic hydroxyl groups in the lignin molecular structure provide strong absorption and shielding against ultraviolet rays, effectively delaying coating aging without the need for additional aging aids. Detailed Implementation

[0016] The present invention will now be described in detail with reference to specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0017] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Unless otherwise specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0018] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0019] Example 1 I. This embodiment provides a scratch-resistant, antibacterial, matte black coating for plastic substrates, comprising the following components in parts by weight: The preparation method of modified nanocellulose is as follows: (1) Weigh 5g of enzymatically hydrolyzed lignin and place it in a container. Add 45g of acetone aqueous solution with a volume fraction of 70% and dissolve it completely. Stir at 500rpm for 1h, concentrate by rotary evaporation at 45℃, cool and dry to obtain lignin colloidal spheres. (2) Disperse the lignin colloidal spheres in 250 mL of anhydrous ethanol and sonicate for 30 min to obtain a lignin colloidal dispersion; (3) Place 50ml of lignin colloidal dispersion in a 250ml three-necked flask and turn on magnetic stirring to ensure uniform dispersion of the colloid; (4) Adjust the pH to about 3 with 0.1 mol / L dilute hydrochloric acid, and heat to 50°C. Add 50% glutaraldehyde solution dropwise while stirring. Stop adding when dark brown powder precipitates in the solution. Keep the temperature and continue the reaction for 12 hours. (5) The well-reacted mixture is centrifuged and washed with water more than 3 times, and then placed in a 40℃ oven to dry for 6 hours to obtain nano-modified lignin.

[0020] II. The preparation method of the scratch-resistant, antibacterial, matte black coating in this embodiment includes the following steps: (1) Add the dispersant and acrylic resin to the solvent and stir at a low speed of 400 rpm / min for 10 minutes to obtain the first mixture; (2) Add carbon black, nano-modified lignin and anti-settling agent to the first mixture under stirring, stir at 1000 rpm / min for 30 minutes, grind to a fineness of less than 10 μm on a grinder to obtain the second mixture; (3) Add nano matte powder and leveling agent to the second mixture under stirring, disperse at high speed of 1000 rpm / min for 30 minutes, and the fineness is less than 20 μm to obtain scratch-resistant and antibacterial matte black coating.

[0021] Performance test panel preparation: Scratch-resistant and antibacterial matte black paint is mixed evenly with Covestro Desmodur N3390 and butyl acetate at a mass ratio of 100:10:60, and then coated onto an ABS plastic substrate. It is then flash-dried at room temperature for 5-10 minutes. After baking at 80℃ for 1 hour, it is removed, cooled, and allowed to stand at room temperature for 7 days before performance testing.

[0022] The performance of the paint film obtained in this embodiment was tested, and the results are shown in Table 1 below: Table 1 Example 2 I. This embodiment provides a scratch-resistant, antibacterial, matte black coating for plastic substrates, comprising the following components in parts by weight: The preparation method of modified nanocellulose is as follows: (1) Weigh 5g of enzymatically hydrolyzed lignin and place it in a container. Add 45g of acetone aqueous solution with a volume fraction of 70% and dissolve it completely. Stir at 500rpm for 1h, concentrate by rotary evaporation at 45℃, cool and dry to obtain lignin colloidal spheres. (2) Disperse the lignin colloidal spheres in 250 mL of anhydrous ethanol and sonicate for 30 min to obtain a lignin colloidal dispersion; (3) Place 50ml of lignin colloidal dispersion in a 250ml three-necked flask and turn on magnetic stirring to ensure uniform dispersion of the colloid; (4) Adjust the pH to about 3 with 0.1 mol / L dilute hydrochloric acid, and heat to 50°C. Add 50% glutaraldehyde solution dropwise while stirring. Stop adding when dark brown powder precipitates in the solution. Keep the temperature and continue the reaction for 12 hours. (5) The well-reacted mixture is centrifuged and washed with water more than 3 times, and then placed in a 40℃ oven to dry for 6 hours to obtain nano-modified lignin.

[0023] II. The preparation method of the scratch-resistant, antibacterial, matte black coating in this embodiment includes the following steps: (1) Add the dispersant and acrylic resin to the solvent and stir at a low speed of 400 rpm / min for 10 minutes to obtain the first mixture; (2) Add carbon black, nano-modified lignin and anti-settling agent to the first mixture under stirring, stir at 1000 rpm / min for 30 minutes, grind to a fineness of less than 10 μm on a grinder to obtain the second mixture; (3) Add nano matte powder and leveling agent to the second mixture under stirring, disperse at high speed of 1000 rpm / min for 30 minutes, and the fineness is less than 20 μm to obtain scratch-resistant and antibacterial matte black coating.

[0024] Performance test panel preparation: Scratch-resistant and antibacterial matte black paint is mixed evenly with Covestro Desmodur N3390 and butyl acetate at a mass ratio of 100:10:60, and then coated onto an ABS plastic substrate. It is then flash-dried at room temperature for 5-10 minutes. After baking at 80℃ for 1 hour, it is removed, cooled, and allowed to stand at room temperature for 7 days before performance testing.

[0025] The performance of the paint film obtained in this embodiment was tested, and the results are shown in Table 2 below: Table 2 Comparative Example 1 I. This comparative example provides a scratch-resistant, antibacterial, matte black coating for a plastic substrate, comprising the following components in parts by weight: II. The preparation method of the scratch-resistant, antibacterial, matte black coating in this comparative example includes the following steps: (1) Add the dispersant and acrylic resin to the solvent and stir at a low speed of 400 rpm / min for 10 minutes to obtain the first mixture; (2) Add carbon black and anti-settling agent to the first mixture under stirring, stir at 1000 rpm / min for 30 minutes, and grind to a fineness of less than 10 μm to obtain the second mixture; (3) Add nano matte powder and leveling agent to the second mixture under stirring, disperse at high speed of 1000 rpm / min for 30 minutes, and the fineness is less than 20 μm to obtain matte black coating.

[0026] Performance test panel preparation: Mix matte black paint with Covestro Desmodur N3390 and butyl acetate at a mass ratio of 100:10:60, then coat the mixture onto an ABS plastic substrate and flash dry at room temperature for 5-10 minutes; after baking at 80℃ for 1 hour, remove and cool, and allow to stand at room temperature for 7 days before performance testing.

[0027] The coating film obtained in this embodiment was subjected to relevant performance tests, and the results are shown in Table 3 below: Table 3 A comparison of the coating formulations in Examples 1 and 2 with Comparative Example 1 clearly shows that Comparative Example 1 did not contain nano-modified lignin, while Example 1 contained 3 parts by weight of nano-modified lignin, and Example 2 contained 5 parts by weight. The only difference among the three formulations lies in this core bio-based functional component. After preparing films from the three formulations and completing standardized performance tests, the key properties of the coating films showed significant differences, and the test results were intuitive and statistically significant. Based on the measured data in Tables 1, 2, and 3, it can be seen that: Comparative Example 1, without nano-modified lignin, only achieved a wear resistance level of 3 and an antibacterial rate of less than 90%, failing to meet the national standard's mandatory requirements for scratch-resistant, antibacterial, and matte coatings; Example 1, with 3 parts by weight of nano-modified lignin, fully met the standards for scratch resistance, wear resistance, and antibacterial properties; and Example 2, with 5 parts by weight of nano-modified lignin, achieved optimal levels in wear resistance, antibacterial rate, and light aging resistance. The above results fully demonstrate that nano-modified lignin is the core functional component for improving the scratch resistance and antibacterial properties of the coating film. Its addition amount is positively correlated with the performance improvement. At the same time, it can also synergistically optimize the light aging resistance of the coating, delay the loss of gloss and discoloration of the coating, and further extend the service life of the coating.

[0028] In summary, the scratch-resistant, antibacterial, matte black coating provided by this invention can be applied in the automotive, consumer electronics, and medical equipment industries. The addition of nano-modified lignin significantly improves the scratch resistance and antibacterial properties of the coating film, further enhancing its protective properties. Simultaneously, this bio-based nanomaterial is a renewable resource, low in cost, and environmentally friendly.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A scratch-resistant, antibacterial, matte black coating for use on plastic substrates, characterized in that, The components include the following parts by weight: 40-60 parts of acrylic resin; 2-5 parts carbon black; 0-10 parts of nano-modified lignin, wherein 0 parts of nano-modified lignin are not included; 1-10 parts of nano matting powder; 1-5 parts dispersant; Leveling agent 0.1-1 part; Anti-settling agent 0.1-1 part; Solvent 5-30 parts.

2. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The acrylic resin mentioned is an acrylic resin with medium hydroxyl content and high TG point.

3. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The carbon black is a high-pigment carbon black, selected from commercially available Evonik FW-200.

4. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The preparation method of the aforementioned nano-modified lignin is as follows: Take lignin, acetone and water, stir and mix, concentrate by rotary evaporation, cool and dry to obtain lignin colloidal spheres; disperse the lignin colloidal spheres in anhydrous ethanol, and disperse by ultrasonication to obtain lignin colloidal dispersion; Adjust the pH to acidic, add glutaraldehyde solution while stirring, and stop when dark brown powder precipitates. After the reaction is complete, centrifuge and wash the product multiple times, and dry to obtain nano-modified lignin.

5. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The matting powder is nano-sized fumed silica with a particle size between 20-40 nm.

6. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The dispersant is a high molecular weight acrylic block copolymer.

7. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The leveling agent is a polyether-modified polydimethylsiloxane copolymer solution.

8. The scratch-resistant, antibacterial, matte black coating for use on plastic substrates according to claim 1, characterized in that, The anti-settling agent includes one of bentonite or fumed silica.

9. A method for preparing a scratch-resistant, antibacterial, matte black coating for use on a plastic substrate as described in any one of claims 1-8, characterized in that, Includes the following steps: The dispersant and acrylic resin were added to the solvent and stirred at low speed for 10 minutes to obtain the first mixture; Carbon black, nano-modified lignin, and anti-settling agent are added to the first mixture under stirring, and the mixture is ground to a fineness of less than 10 μm to obtain the second mixture. Nano-matte powder and leveling agent are added to the second mixture under stirring. After dispersion and mixing, a scratch-resistant and antibacterial matte black coating is obtained.

10. An application of a scratch-resistant, antibacterial, matte black coating as described in any one of claims 1-8 on a plastic substrate, characterized in that, It is used in plastic substrates for consumer electronics, home appliances, automotive interior and exterior trim, and medical devices.

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