Matt anti-aging coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a matt anti-aging coating and a preparation method thereof.The matt anti-aging coating is prepared from, by weight, 86-95 parts of waterborne polyurethane, 2-10 parts of silicon dioxide matting powder, 0.2-1.2 parts of modified polyether dispersing agent and the like; a side chain of the modified polyether dispersant contains a hydrophilic polyoxyethylene ether chain segment which can be used as a solvation chain, and also contains a sodium carboxylate group which can be used as an anchoring group to play a role in dispersing silicon dioxide, so that the dispersity and the stability of the coating are improved. And the tensile strength of the coating adhesive film is higher. The modified polyether dispersant contains 2-hydroxyl and benzophenone ultraviolet absorbing groups which are uniformly distributed in the aqueous emulsion and the cured adhesive film, so that the adhesive film shows excellent ultraviolet resistance, and meanwhile, the paint film is low in glossiness and shows a good matte effect.

Description

Technical Field

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

[0002] Matt paint has low gloss and unique matte properties, and is widely used in wall coating, furniture decoration materials, signs, etc. Matting agents such as silica matting powder, aluminum oxide, calcium carbonate, etc. are usually added to the paint to increase the surface roughness and diffusely reflect light on the surface, thereby achieving matte and matte effects.

[0003] The dispersibility of traditional silica matting powder in water-based coatings such as polyurethane is poor, and it is easy to agglomerate and flocculate, which seriously affects the stability, leveling and mechanical properties of the coating film, so it is necessary to add a dispersant. Chinese patent CN104946116B discloses that the polyurethane matte coating prepared with fumed silica matting powder, polyurethane-type polymer dispersant, micro-branched polyester polyol, polyisocyanate, etc. as raw materials has good self-repairing function, but the patent does not improve the anti-ultraviolet aging performance of polyurethane coatings. Adding anti-ultraviolet absorbers to the coating can improve the anti-ultraviolet aging performance of the coating film. Although the common 2-hydroxybenzophenone class has excellent ultraviolet absorption performance, it is not water-soluble, which is not conducive to its practical application in water-based coatings. Summary of the invention

[0004] The invention provides a matte aging-resistant coating and a preparation method thereof, and solves the problem that the polyurethane coating has no matte performance and poor anti-ultraviolet aging performance.

[0005] The technical solution of the present invention is: a matte aging-resistant coating, comprising 86-95 parts by weight of waterborne polyurethane, 2-10 parts by weight of silicon dioxide 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.

[0006] The preparation method of the matte aging-resistant coating 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, and obtaining the matte aging-resistant coating.

[0007] Preferably, the preparation method of the modified polyether dispersant is: (1) Add 102-108 parts by weight of diethylenetriamine to ethanol, dropwise add an aqueous solution containing 100 parts by weight of glutaraldehyde, stir for reaction, add 126-168 parts by weight of sodium carbonate and 600-1200 parts by weight of chloropolyethylene glycol monomethyl ether, stir for reaction, 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: .

[0008] (2) Add 100 parts by weight of polyether precursor and 6.4-9.6 parts by weight of sodium borohydride to ethanol, stir for reaction, and then 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: .

[0009] (3) Add 100 parts by weight of imino polyether dispersant precursor, 38-46 parts by weight of sodium carbonate, 8.2-13.8 parts by weight of sodium chloroacetate, 4.2-7.6 parts by weight of 2-hydroxy-4-chloroacetate-benzophenone (CAS registration number 21122-09-8, structural formula: ), after stirring the reaction, 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: .

[0010] Preferably, 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.

[0011] Preferably, the reaction temperature in (2) is 20-30° C. and the reaction time is 4-6 h.

[0012] Preferably, the reaction temperature in (3) is 45-60°C and the reaction time is 10-15h.

[0013] The beneficial technical effect of the present invention is as follows: the present invention uses diethylenetriamine, an aqueous solution of glutaraldehyde, chloropolyethylene 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 be used as a solvation chain, and also contains a sodium carboxylate group, which can be used as an anchoring group, interacting with the surface of the silica matting powder, and coating the surface of the silica, thereby playing a role in dispersing silica, so that the silica matting powder is evenly dispersed in the aqueous polyurethane emulsion, and is not easy to form a precipitate, thereby improving the dispersibility and stability of the coating. In addition, the more evenly the silica matting powder is dispersed, the better the mechanical properties of the coating film are, and the higher the tensile strength is.

[0014] The modified polyether dispersant of the present invention contains 2-hydroxyl and benzophenone ultraviolet absorption groups. Since the modified polyether dispersant contains hydrophilic sodium carboxylate and polyether molecular chains, the dispersant can be uniformly dispersed in the coating aqueous emulsion, so that the 2-hydroxyl and benzophenone structures can also be uniformly distributed in the aqueous emulsion and the cured adhesive film, so that the adhesive film exhibits excellent anti-ultraviolet performance, and after ultraviolet aging, the adhesive film still has high tensile strength and retention rate. At the same time, the paint film has low glossiness and presents a good matte effect. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0016] 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.

[0017] Chloropolyethylene glycol monomethyl ether was prepared according to the method of Hainan University's master's thesis "Synthesis, Characterization and Properties of Side-Chain Hyperbranched Polycarboxylic Acid Water-Reducing Agent".

[0018] Add 0.1 mol of polyethylene glycol monomethyl ether 500 ( ), 0.2 mol of dry potassium carbonate, heated to 43°C, added dropwise 100 mL of dichloromethane solution containing 36.5 mL of thionyl chloride, condensed and refluxed for 24 hours, cooled and filtered to remove carbonate, and the filtrate was concentrated under reduced pressure to obtain chloropolyethylene glycol monomethyl ether. The structural formula is .

[0019] Example 1 (1) Add 1.02 g of diethylenetriamine to 30 mL of ethanol, add dropwise 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 chloropolyethylene 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.

[0020] (2) Add 10 g of 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.

[0021] (3) Add 5 g of 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.

[0022] (4) 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 and stir to obtain a matte aging-resistant coating.

[0023] Example 2 (1) Add 1.08 g of diethylenetriamine to 40 mL of ethanol, add dropwise 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 chloropolyethylene 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.

[0024] (2) Add 10 g of 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.

[0025] (3) Add 5 g of imino polyether 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 a modified polyether dispersant.

[0026] (4) Add 913 g of waterborne polyurethane, 50 g of silica matting powder, 6 g of modified polyether dispersant, 10 g of defoamer TEGO-825, 3 g of leveling agent TEGO-2300, and 18 g of thickener into the container and stir to obtain a matte aging-resistant coating.

[0027] Example 3 (1) Add 1.02 g of diethylenetriamine to 40 mL of ethanol, add dropwise 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 chloropolyethylene 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 a polyether precursor.

[0028] (2) Add 10 g of 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 an imino polyether dispersant precursor.

[0029] (3) Add 5 g of imino polyether 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 a modified polyether dispersant.

[0030] (4) Add 889 g of waterborne polyurethane, 75 g of silica matting powder, 9 g of modified polyether dispersant, 6 g of defoamer TEGO-825, 8 g of leveling agent TEGO-2300, and 13 g of thickener into the container and stir to obtain a matte aging-resistant coating.

[0031] Example 4 (1) Add 860 g of waterborne polyurethane, 100 g of silica matting powder, 12 g of modified polyether dispersant (prepared in the same manner 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 to obtain a matte aging-resistant coating.

[0032] Comparative Example 1 (1) Add 950g of waterborne polyurethane, 20g of silica matting powder, 6g of defoaming agent TEGO-825, 5g of leveling agent TEGO-2300, and 17g of thickener into a container and stir to obtain a matte aging-resistant coating.

[0033] Comparative Example 2 (1) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of polyether precursor (prepared in the same manner 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 to obtain a matte aging-resistant coating.

[0034] Comparative Example 3 (1) Add 5 g of 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 a modified polyether dispersant.

[0035] (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 and stir to obtain a matte aging-resistant coating.

[0036] Comparative Example 4 (1) Add 5 g of imino polyether dispersant precursor (prepared in the same manner as in Example 1), 2 g of sodium carbonate, 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.

[0037] (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 and stir to obtain a matte aging-resistant coating.

[0038] Comparative Example 5 (1) Add 5 g of 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 a modified polyether dispersant, which is then mixed with 0.3 g of 2-hydroxybenzophenone (CAS registration number 117-99-7, structural formula: ) are stirred and blended to obtain a benzophenone-modified polyether dispersant blend.

[0039] (2) Add 950 g of waterborne polyurethane, 20 g of silica matting powder, 2 g of benzophenone-modified polyether dispersant blend, 6 g of defoamer TEGO-825, 5 g of leveling agent TEGO-2300, and 17 g of thickener into a container and stir to obtain a matte aging-resistant coating.

[0040] The coating was left at room temperature for 15 days and the dispersion of the coating was observed.

[0041] The paint was dried at 90°C for 8 hours to form a paint film, and the 60° specular glossiness was tested according to the GB / T 9754-2007 method.

[0042] Test the tensile strength of the cured coating film according to GB / T 528-2009 method. Test three times and take the average value.

[0043] The coating cured film was aged in a UV aging test chamber for 240 hours. The UV lamp had a neutral wavelength of 340nm and a power of 160W. Then the tensile strength after UV aging was tested. The test was repeated 3 times and the average value was taken.

[0044] The test results are shown in Table 1.

[0045] Table 1 Coating performance test

[0046] As shown in Table 1, compared with Comparative Example 1, the modified polyether dispersant is added to the polyurethane water-based coating of Examples 1-4, and its side chain contains a hydrophilic polyoxyethylene ether segment, which can be used as a solvation chain, and contains a sodium carboxylate group, which can be used as an anchoring group, interacting with the surface of the silica matting powder, playing a role in dispersing silica, so that the silica matting powder is evenly dispersed in the aqueous polyurethane water emulsion, and it is not easy to form a precipitate, 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, and the higher the tensile strength. At the same time, the modified polyether dispersant contains 2-hydroxyl 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-hydroxyl and benzophenone structures can also be evenly distributed in the water emulsion and the cured film, so that the film exhibits excellent anti-ultraviolet performance, and after ultraviolet aging, the film still has a high tensile strength and retention rate. However, as the amount of modified polyether dispersant increases, the silica matting powder is dispersed too evenly, the roughness of the paint film surface decreases, and the glossiness of the coating increases, resulting in a worse matte effect, which is not conducive to the matte effect.

[0047] The polyether precursor added in Comparative Example 2 does not contain sodium carboxylate anchoring groups, and cannot disperse 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-hydroxyl and benzophenone UV absorption groups. After UV aging, the tensile strength and retention rate of the film are very low, and the anti-UV aging performance is poor.

[0048] The modified polyether dispersant added in Comparative Example 3 contains sodium carboxylate anchoring groups, which can disperse the silica matting powder, is not easy to form sediment, and has high tensile strength of the coating film. However, it does not contain 2-hydroxyl and benzophenone UV absorption groups. After UV aging, the tensile strength and retention rate of the film are very low, and the anti-UV aging performance is poor.

[0049] The modified polyether dispersant of Comparative Example 4 does not contain a sodium carboxylate anchoring group and cannot disperse the silica matting powder, resulting in poor dispersibility of the silica matting powder, easy formation of sediments, and affecting the tensile strength of the film.

[0050] In Comparative Example 5, the modified polyether dispersant and 2-hydroxybenzophenone are blended, and the 2-hydroxybenzophenone structure is not introduced into the polyether dispersant. Due to the poor water solubility of 2-hydroxybenzophenone, the dispersibility in the aqueous 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.

[0051] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall 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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