A matte anti-aging coating and its preparation method

Abstract

The present invention relates to the technical field of coatings, and discloses a matte anti-aging coating and a preparation method thereof. The matte anti-aging coating of the present invention comprises 86-95 parts by weight of waterborne polyurethane, 2-10 parts by weight of silica matting powder, 0.2-1.2 parts by weight of modified polyether dispersant, etc.; the side chain of the modified polyether dispersant contains a hydrophilic polyoxyethylene ether chain segment, which can serve as a solvation chain, and at the same time contains a sodium carboxylate group, which can serve as an anchoring group, playing a role in dispersing silica, improving the dispersibility and stability of the coating. And the tensile strength of the coating film is higher. The modified polyether dispersant contains 2-hydroxy and benzophenone ultraviolet absorption groups, which are uniformly distributed in the water emulsion and the cured film, enabling the film to exhibit excellent ultraviolet resistance, and at the same time the gloss of the paint film is low, presenting a good matte effect.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and specifically to a matte anti-aging coating and a preparation method thereof. Background Art

[0002] Matte coatings have low gloss and exhibit unique matte properties, and are widely used in wall painting, furniture decoration materials, markers, etc. Usually, a matting agent is added to the coating, such as silica matting powder, alumina, calcium carbonate, etc. By increasing the surface roughness, light is diffusely reflected on the surface, thereby achieving a matting and matte effect.

[0003] Traditional silica matting powder has poor dispersibility in waterborne coatings such as polyurethane, and is prone to agglomeration and flocculation phenomena, seriously affecting the stability, leveling property of the coating and the mechanical properties of the paint film. Therefore, a dispersant needs to be added. Chinese Patent CN104946116B discloses that a polyurethane matte coating prepared from fumed silica matting powder, polyurethane-based polymer dispersant, micro-branched polyester polyol, polyisocyanate, etc. has good self-healing function, but this patent does not improve the anti-ultraviolet aging and other properties of polyurethane coatings. Adding an anti-ultraviolet absorber to the coating can improve the anti-ultraviolet aging performance of the paint film of the coating. Although common 2-hydroxybenzophenone has excellent ultraviolet absorption performance, its water solubility is poor, which is not conducive to its practical application in waterborne coatings. Summary of the Invention

[0004] The present invention provides a matte anti-aging coating and a preparation method thereof, and solves the problems that polyurethane coatings do not have matte properties and have poor anti-ultraviolet aging performance.

[0005] The technical solution of the present invention is: a matte anti-aging coating, comprising 86-95 parts by weight of waterborne polyurethane, 2-10 parts by weight of silica matting powder, 0.2-1.2 parts by weight of modified polyether dispersant, 0.6-1 part by weight of defoamer, 0.3-0.8 part by weight of leveling agent, and 1.3-1.8 parts by weight of thickener.

[0006] The preparation method of the matte anti-aging coating is: adding waterborne polyurethane, silica matting powder, modified polyether dispersant, defoamer, leveling agent, and thickener into a container, and stirring and mixing evenly to obtain the matte anti-aging coating.

[0007] Preferably, the preparation method of the modified polyether dispersant is:

[0008] (1) Add 102 - 108 parts by weight of diethylenetriamine to ethanol, dropwise add an aqueous solution containing 100 parts by weight of glutaraldehyde, after stirring and reacting, add 126 - 168 parts by weight of sodium carbonate and 600 - 1200 parts by weight of chlorinated polyethylene glycol monomethyl ether. After stirring and reacting, concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain a polyether precursor. The reaction formula is as follows:

[0009] .

[0010] (2) Add 100 parts by weight of the polyether precursor and 6.4 - 9.6 parts by weight of sodium borohydride to ethanol. After stirring and reacting, concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain an imino polyether dispersant precursor. The reaction formula is as follows:

[0011] .

[0012] (3) Add 100 parts by weight of the imino polyether dispersant precursor, 38 - 46 parts by weight of sodium carbonate, 8.2 - 13.8 parts by weight of sodium chloroacetate, and 4.2 - 7.6 parts by weight of 2 - hydroxy - 4 - chloroacetate - benzophenone (CAS registration number: 21122 - 09 - 8, structural formula is ) to water. After stirring and reacting, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain a modified polyether dispersant. The reaction formula is as follows:

[0013] .

[0014] Preferably, in (1), the temperature of the first reaction is 50 - 65 °C, and the reaction time is 4 - 10 h; the temperature of the second reaction is 40 - 60 °C, and the reaction time is 10 - 18 h.

[0015] Preferably, in (2), the reaction temperature is 20 - 30 °C, and the reaction time is 4 - 6 h.

[0016] Preferably, in (3), the reaction temperature is 45 - 60 °C, and the reaction time is 10 - 15 h.

[0017] The beneficial technical effects of the present invention are as follows: The present invention uses diethylenetriamine, an aqueous solution of glutaraldehyde, chlorinated polyethylene glycol monomethyl ether, sodium chloroacetate, and 2-hydroxy-4-chloroacetate benzophenone as reactants to prepare a modified polyether dispersant. Its side chain contains a hydrophilic polyoxyethylene ether segment, which can serve as a solvation chain, and at the same time contains a carboxylate group, which can serve as an anchoring group, interact with the surface of the silica matting powder, coat the surface of the silica, and thus play a role in dispersing the silica, making the silica matting powder evenly dispersed in the aqueous polyurethane water emulsion, not easily forming precipitates, and improving the dispersibility and stability of the coating. Moreover, the more evenly the silica matting powder is dispersed, the better the mechanical properties of the coating film and the higher the tensile strength.

[0018] The modified polyether dispersant of the present invention contains 2-hydroxy and benzophenone ultraviolet absorption groups. Since the modified polyether dispersant contains hydrophilic carboxylate and polyether molecular chains, the dispersant can be evenly dispersed in the coating water emulsion, so that the 2-hydroxy and benzophenone structures can also be evenly distributed in the water emulsion and the cured film, making the film exhibit excellent ultraviolet resistance. After ultraviolet aging, the film still has a high tensile strength and retention rate. At the same time, the gloss of the paint film is low, showing a good matte effect. Specific embodiments

[0019] The following further illustrates the present invention with specific examples, but the protection scope of the present invention is not limited thereto.

[0020] The following waterborne polyurethane, model HBHK-1007, water emulsion, solid content 50%, Guangzhou Black Panther Waterproof Building Materials Co., Ltd. Silica matting powder, model OK520, average particle size 6.5um, Guangzhou Yinuo Chemical Technology Co., Ltd. Thickener, model SN-THCKENER 612, Guangzhou Chengzhenhao Trading Co., Ltd.

[0021] According to the method of the master's thesis of Hainan University, "Synthesis, Characterization and Properties of Side Chain Hyperbranched Polycarboxylate Water Reducing Agents", chlorinated polyethylene glycol monomethyl ether was prepared.

[0022] Add 0.1 mol of polyethylene glycol monomethyl ether 500 ( ) and 0.2 mol of dry potassium carbonate to 100 mL of dichloromethane, heat to 43 °C, dropwise add 100 mL of a dichloromethane solution containing 36.5 mL of thionyl chloride, carry out a condensation reflux reaction for 24 h, filter by suction to remove carbonates after cooling, and concentrate the filtrate under reduced pressure to obtain chlorinated polyethylene glycol monomethyl ether. The structural formula is .

[0023] Example 1

[0024] (1) Add 1.02 g of diethylenetriamine to 30 mL of ethanol, dropwise add 2 mL of an aqueous solution containing 1 g of glutaraldehyde, stir and react at 60 °C for 6 h, add 1.45 g of sodium carbonate and 6 g of chloro-polyethylene glycol monomethyl ether, stir and react at 60 °C for 10 h, concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure and dry to obtain a polyether precursor.

[0025] (2) Add 10 g of the polyether precursor and 0.78 g of sodium borohydride to 120 mL of ethanol, stir and react at 20 °C for 6 h, concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure and dry to obtain an imino-polyether dispersant precursor.

[0026] (3) Add 5 g of the imino-polyether dispersant precursor, 2 g of sodium carbonate, 0.56 g of sodium chloroacetate and 0.3 g of 2-hydroxy-4-chloroacetate benzophenone to 120 mL of water, stir and react at 60 °C for 10 h, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure and dry to obtain a modified polyether dispersant.

[0027] (4) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of the modified polyether dispersant, 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300 and 17 g of thickener to a container, stir and mix evenly to obtain a matte anti-aging coating.

[0028] Example 2

[0029] (1) Add 1.08 g of diethylenetriamine to 40 mL of ethanol, dropwise add 2 mL of an aqueous solution containing 1 g of glutaraldehyde, stir and react at 50 °C for 10 h, add 1.68 g of sodium carbonate and 12 g of chloro-polyethylene glycol monomethyl ether, stir and react at 40 °C for 18 h, concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure and dry to obtain a polyether precursor.

[0030] (2) Add 10 g of the polyether precursor and 0.96 g of sodium borohydride to 150 mL of ethanol, stir and react at 30 °C for 4 h, concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure and dry to obtain an imino-polyether dispersant precursor.

[0031] (3) Add 5 g of the polyether imide dispersant precursor, 1.9 g of sodium carbonate, 0.69 g of sodium chloroacetate, and 0.21 g of 2-hydroxy-4-chloroacetate benzophenone to 100 mL of water. Stir and react at 45 °C for 15 h. Add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain the modified polyether dispersant.

[0032] (4) Add 913 g of waterborne polyurethane, 50 g of silica matting powder, 6 g of the modified polyether dispersant, 10 g of defoamer TEGO-825, 3 g of leveling agent TEGO-2300, and 18 g of thickener to a container, and stir and mix evenly to obtain the matte anti-aging coating.

[0033] Example 3

[0034] (1) Add 1.02 g of diethylenetriamine to 40 mL of ethanol, dropwise add 2 mL of an aqueous solution containing 1 g of glutaraldehyde, stir and react at 65 °C for 4 h. Add 1.26 g of sodium carbonate and 12 g of chlorinated polyethylene glycol monomethyl ether, stir and react at 50 °C for 18 h. Concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain the polyether precursor.

[0035] (2) Add 10 g of the polyether precursor and 0.64 g of sodium borohydride to 100 mL of ethanol, stir and react at 20 °C for 6 h. Concentrate under reduced pressure to remove ethanol, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain the polyether imide dispersant precursor.

[0036] (3) Add 5 g of the polyether imide dispersant precursor, 2.3 g of sodium carbonate, 0.41 g of sodium chloroacetate, and 0.38 g of 2-hydroxy-4-chloroacetate benzophenone to 150 mL of water. Stir and react at 55 °C for 10 h. Add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain the modified polyether dispersant.

[0037] (4) Add 889 g of waterborne polyurethane, 75 g of silica matting powder, 9 g of the modified polyether dispersant, 6 g of defoamer TEGO-825, 8 g of leveling agent TEGO-2300, and 13 g of thickener to a container, and stir and mix evenly to obtain the matte anti-aging coating.

[0038] Example 4

[0039] (1) Add 860 g of waterborne polyurethane, 100 g of silica matting powder, 12 g of modified polyether dispersant (prepared in the same way as in Example 1), 7 g of defoamer TEGO-825, 8 g of leveling agent TEGO-2300, and 13 g of thickener into a container, stir and mix evenly to obtain a matte anti-aging coating.

[0040] Comparative Example 1

[0041] (1) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300, and 17 g of thickener into a container, stir and mix evenly to obtain a matte anti-aging coating.

[0042] Comparative Example 2

[0043] (1) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of polyether precursor (prepared in the same way as in Example 1), 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300, and 17 g of thickener into a container, stir and mix evenly to obtain a matte anti-aging coating.

[0044] Comparative Example 3

[0045] (1) Add 5 g of imino polyether dispersant precursor (prepared in the same way as in Example 1), 2 g of sodium carbonate, and 0.56 g of sodium chloroacetate into 120 mL of water, stir and react at 60 °C for 10 h, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain a modified polyether dispersant.

[0046] (2) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of modified polyether dispersant, 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300, and 17 g of thickener into a container, stir and mix evenly to obtain a matte anti-aging coating.

[0047] Comparative Example 4

[0048] (1) Add 5 g of imino polyether dispersant precursor (prepared in the same way as in Example 1), 2 g of sodium carbonate, and 0.3 g of 2-hydroxy-4-chloroacetate benzophenone into 120 mL of water, stir and react at 60 °C for 10 h, add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain a modified polyether dispersant.

[0049] (2) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of modified polyether dispersant, 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300, and 17 g of thickener into a container, stir and mix evenly to obtain a matte anti-aging coating.

[0050] Comparative Example 5

[0051] (1) Add 5 g of the imino polyether dispersant precursor (prepared in the same manner as in Example 1), 2 g of sodium carbonate, and 0.56 g of sodium chloroacetate to 120 mL of water. Stir and react at 60 °C for 10 h. Add saturated sodium chloride solution, extract with dichloromethane, collect the dichloromethane organic phase, concentrate under reduced pressure, and dry to obtain the modified polyether dispersant. Then, stir and blend it with 0.3 g of 2-hydroxybenzophenone (CAS Registry Number 117-99-7, with the structural formula ) to obtain a benzophenone-modified polyether dispersant blend.

[0052] (2) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of the benzophenone-modified polyether dispersant blend, 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300, and 17 g of thickener to a container, and stir and mix evenly to obtain a matte anti-aging coating.

[0053] Leave the coating at room temperature for 15 days and observe the dispersion of the coating.

[0054] Dry the coating at 90 °C for 8 h to form a paint film, and test the 60° specular gloss according to the method of GB / T 9754-2007.

[0055] Test the tensile strength of the cured coating film according to the method of GB / T 528-2009. Test 3 times and take the average value.

[0056] Place the cured coating film in an ultraviolet aging test chamber for ultraviolet light aging for 240 h. The neutral wavelength of the ultraviolet lamp is 340 nm and the power is 160 W. Then, test the tensile strength after ultraviolet light aging. Test 3 times and take the average value.

[0057] The test results are shown in Table 1.

[0058] Table 1 Coating Performance Test

[0059]

[0060] As can be seen from Table 1, compared with Comparative Example 1, a modified polyether dispersant is added to the polyurethane waterborne coatings in Examples 1-4. Its side chain contains a hydrophilic polyoxyethylene ether segment, which can serve as a solvation chain, and at the same time contains a sodium carboxylate group, which can serve as an anchoring group. It interacts with the surface of the silica matting powder, plays a role in dispersing the silica, and makes the silica matting powder evenly dispersed in the aqueous polyurethane emulsion, and is not easy to form precipitates, thereby improving the dispersibility and stability of the coating. And the more evenly the silica matting powder is dispersed, the better the mechanical properties of the coating film, with high tensile strength. At the same time, the modified polyether dispersant contains 2-hydroxy and benzophenone ultraviolet absorption groups. Since the modified polyether dispersant contains hydrophilic sodium carboxylate and polyether molecular chains, the dispersant can be evenly dispersed in the coating water emulsion, so that the 2-hydroxy and benzophenone structures can also be evenly distributed in the water emulsion and the cured film, making the film exhibit excellent anti-ultraviolet performance. After ultraviolet aging, the film still has a high tensile strength and retention rate. However, as the dosage of the modified polyether dispersant increases, the silica matting powder is dispersed too evenly, the roughness of the paint film surface decreases, and the gloss of the coating becomes larger, resulting in a poor matting effect and being not conducive to the matte effect.

[0061] The polyether precursor added in Comparative Example 2 does not contain a sodium carboxylate anchoring group and cannot play a role in dispersing the silica matting powder, resulting in poor dispersibility of the silica matting powder, easy formation of sediment, and affecting the tensile strength of the film. At the same time, the polyether precursor does not contain 2-hydroxy and benzophenone ultraviolet absorption groups. After ultraviolet aging, the tensile strength and retention rate of the film are very low, and the anti-ultraviolet aging performance is poor.

[0062] The modified polyether dispersant added in Comparative Example 3 contains a sodium carboxylate anchoring group, can play a role in dispersing the silica matting powder, is not easy to form sediment, and the tensile strength of the coating film is high, but does not contain 2-hydroxy and benzophenone ultraviolet absorption groups. After ultraviolet aging, the tensile strength and retention rate of the film are very low, and the anti-ultraviolet aging performance is poor.

[0063] The modified polyether dispersant in Comparative Example 4 does not contain a sodium carboxylate anchoring group and cannot play a role in dispersing the silica matting powder, resulting in poor dispersibility of the silica matting powder, easy formation of sediment, and affecting the tensile strength of the film.

[0064] In Comparative Example 5, the modified polyether dispersant and 2-hydroxybenzophenone were blended, and the 2-hydroxybenzophenone structure was not introduced into the polyether dispersant. Due to the poor water solubility of 2-hydroxybenzophenone, its dispersibility in the water emulsion is poor, which is not conducive to improving the anti-ultraviolet aging performance of the coating. After ultraviolet aging, the tensile strength and retention rate of the film are low.

[0065] The present invention is not limited to the above embodiments. Without departing from the essence of the present invention, any variations, improvements, and substitutions that can be conceived by those skilled in the art fall within the scope of the present invention.

Claims

1. A matte aging-resistant coating, characterized in that: The matte aging-resistant coating comprises 86-95 parts by weight of waterborne polyurethane, 2-10 parts by weight of silica matting powder, 0.2-1.2 parts by weight of modified polyether dispersant, 0.6-1 parts by weight of defoamer, 0.3-0.8 parts by weight of leveling agent and 1.3-1.8 parts by weight of thickener; The preparation method of the modified polyether dispersant is: (1) Add diethylenetriamine to ethanol, add dropwise an aqueous solution of glutaraldehyde, stir to react, add sodium carbonate and chloropolyethylene glycol monomethyl ether, stir to react, concentrate under reduced pressure, extract and dry to obtain a polyether precursor; (2) Adding a polyether precursor and sodium borohydride to ethanol, stirring the mixture for reaction, concentrating the mixture under reduced pressure, extracting the mixture, and drying the mixture to obtain an imino polyether dispersant precursor; (3) Add an imino polyether dispersant precursor, sodium carbonate, sodium chloroacetate, and 2-hydroxy-4-chloroacetate-benzophenone into water, stir to react, extract, and dry to obtain a modified polyether dispersant.

2. The matte aging-resistant coating according to claim 1, characterized in that: The amount of glutaraldehyde used in (1) is 100 parts by weight, diethylenetriamine is 102-108 parts by weight, sodium carbonate is 126-168 parts by weight, and chloropolyethylene glycol monomethyl ether is 600-1200 parts by weight.

3. The matte aging-resistant coating according to claim 1, characterized in that: The temperature of the first reaction in (1) is 50-65°C, and the reaction time is 4-10 hours; the temperature of the second reaction is 40-60°C, and the reaction time is 10-18 hours.

4. The matte aging-resistant paint according to claim 1, characterized in that: In the above (2), the amount of the polyether precursor is 100 parts by weight, and the amount of sodium borohydride is 6.4-9.6 parts by weight.

5. The matte aging-resistant paint according to claim 1, characterized in that: The reaction temperature in (2) is 20-30°C and the reaction time is 4-6h.

6. The matte aging-resistant paint according to claim 1, characterized in that: The amount of the imino polyether dispersant precursor in (3) is 100 parts by weight, sodium carbonate is 38-46 parts by weight, sodium chloroacetate is 8.2-13.8 parts by weight, and 2-hydroxy-4-chloroacetate-benzophenone is 4.2-7.6 parts by weight.

7. The matte aging-resistant paint according to claim 1, characterized in that: The reaction temperature in (3) is 45-60°C and the reaction time is 10-15h.

8. A method for preparing the matte aging-resistant coating according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: adding waterborne polyurethane, silicon dioxide matting powder, modified polyether dispersant, defoamer, leveling agent and thickener into a container, stirring and mixing the mixture to obtain a matte aging-resistant coating.

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