Environment-friendly alkali swelling thickening agent for coating and preparation method of environment-friendly alkali swelling thickening agent

Abstract

The invention relates to the technical field of water-based coatings, in particular to an environment-friendly alkali swelling thickener for a coating and a preparation method of the environment-friendly alkali swelling thickener. The environment-friendly alkali swelling thickening agent for the coating is prepared from the following raw materials in percentage by mass: 15 to 25 percent of acrylate monomer, 5 to 10 percent of bio-based methacrylate monomer, 1 to 5 percent of fluorine-containing methacrylate monomer, 1 to 5 percent of emulsifier, 0.5 to 2 percent of bio-enzyme and the balance of deionized water, the thickening agent disclosed by the invention not only is environment-friendly and has good thickening and anti-settling properties, but also can improve the water resistance, post-thickening property and glossiness of the water-based paint.

Description

Technical Field

[0001] The present invention relates to the technical field of water-based coatings, and more specifically to an environmentally friendly alkali swelling thickener for coatings and a preparation method thereof. Background Art

[0002] Water-based paints are widely used in architectural and industrial coatings due to their environmental friendliness and low volatility. For water-based environmentally friendly paints, the viscosity of the paint is a very important indicator, which not only reflects the quality stability of the paint, but also affects the construction performance of the paint and the comprehensive performance of the coating film.

[0003] In the preparation process of water-based coatings, functional additives with certain functions are usually added to increase the application range of the coatings. However, the addition of functional additives often leads to a decrease in the viscosity of water-based coatings. In order to adjust the viscosity of water-based coatings, thickeners are usually added. When a suitable thickener is added to water-based coatings, not only will the viscosity increase, but the leveling rheology and thixotropy of the system will also be significantly improved.

[0004] As people's environmental awareness continues to improve, the requirements for thickeners are getting higher and higher. Bio-based thickeners, such as cellulose, are a good choice, but they may affect the transparency of water-based coatings. In addition, cellulose thickeners have poor viscosity stability under different temperature and pH conditions and are easily affected by environmental factors and lose their thickening effect.

[0005] A Chinese patent with publication number CN114507322A discloses a method for preparing an environmentally friendly light-responsive microgel polymer thickener. The method comprises the following steps: dissolving polyvinyl pyrrolidone PVP and vinyl pyrrolidone NVP in a solvent, adding the mixture to a reaction vessel, successively adding N-isopropyl acrylamide NIPAA and N,N'-methylenebisacrylamide MBA, passing nitrogen to deoxygenate after the mixture is completely dissolved, heating the mixture, adding an initiator ammonium persulfate APS, stirring the mixture evenly, and performing a prepolymerization reaction; after the prepolymerization reaction, the system gradually changes from light blue to milky white, and the mixture is reacted at a constant temperature of 40 to 90° C. for 2 to 6 hours; lowering the temperature to room temperature, adding dibutyltin diacetate, and irradiating the mixture under ultraviolet radiation to obtain an environmentally friendly light-responsive microgel polymer thickener. The environmentally friendly photoresponsive microgel polymer thickener produced by this technical solution can significantly increase the viscosity of the product. The preparation process is environmentally friendly, the reaction scale is controllable, the obtained product has a narrow molecular weight, and has a good thickening effect. However, the dibutyltin diacetate used in this technical solution is an organic tin compound and may pose potential risks to the environment and human health.

[0006] The Chinese patent with publication number CN108976354A discloses an environmentally friendly associative polyurethane composite thickener and its preparation method. During the preparation, polyether polyol, diisocyanate, dihydroxycarboxylic acid, chain extender and hydroxyl-containing end-capping agent are first used to react to obtain polyurethane prepolymer; then organic amine is added to neutralize and form salt, and then silane coupling agent, deionized water and diamine are added in sequence to react to obtain organosilicon-modified polyurethane; then the organosilicon-modified polyurethane is added to deionized water, sodium lauryl sulfate, acrylate monomer and molecular weight regulator are added to obtain pre-emulsion; deionized water is added to the pre-emulsion, heated to 60-65°C, ammonium persulfate is slowly added dropwise while stirring, and after the addition is completed, the temperature is raised to 78-86°C, kept warm for 0.5-1h, and then cooled and filtered. The composite thickener prepared by this technical solution combines anti-settling and thickening, and has good stability, but polyurethane thickeners may cause yellowing of the coating film. Summary of the invention

[0007] The present invention aims to provide an environmentally friendly alkali swelling thickener for coatings and a preparation method thereof. The thickener of the present invention is not only environmentally friendly and has good thickening and anti-settling properties, but also can improve the water resistance, post-thickening and gloss of water-based coatings.

[0008] The first aspect of the present invention provides an environmentally friendly alkali swelling thickener for coatings, which comprises the following raw materials by mass percentage: 15-25% of acrylate monomer, 5-10% of bio-based methacrylate monomer, 1-5% of fluorine-containing methacrylate monomer, 1-5% of emulsifier, 0.5-2% of biological enzyme and the balance of deionized water; The fluorine-containing methacrylate monomer includes hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate; the mass ratio of hexafluorobutyl methacrylate to dodecafluoroheptyl methacrylate is 0.5-1.5:1-1.5; The biological enzyme comprises a mixture of Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B, wherein the mass ratio of the Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B is 2-3:4-6:1.

[0009] Preferably, the mass ratio of hexafluorobutyl methacrylate to dodecafluoroheptyl methacrylate is 1:1.2; Preferably, the mass ratio of the Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B is 2:5:1.

[0010] The inventors accidentally discovered during the experiment that when a fluorinated methacrylate monomer is introduced into a thickener, the surface energy of the thickener is reduced, thereby improving the hydrophobicity of the water-based coating. However, the fluorinated methacrylate monomer is enriched on the air surface, which leads to poor leveling of the water-based coating and affects the gloss of the water-based coating. When hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate are introduced in a mass ratio of 0.5-1.5:1-1.5 into the system of the present invention, in combination with acrylate monomers and bio-based methacrylate monomers, the obtained alkali-swellable thickener can be used in water-based coatings to enable the water-based coatings to have good leveling properties, thereby avoiding a reduction in the gloss of the water-based coatings.

[0011] Preferably, the acrylate monomers include tridecyl acrylate and hexadecyl acrylate; the mass ratio of tridecyl acrylate to hexadecyl acrylate is 4-6:1; preferably 5:1.

[0012] Preferably, the bio-based methacrylate includes heptadecanyl methacrylate and isobornyl methacrylate; the mass ratio of heptadecanyl methacrylate to isobornyl methacrylate is 2:1-3, preferably 2:2.

[0013] The inventors have found that when the biological enzyme is a mixture of Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B, it can synergistically initiate the polymerization reaction of monomers in the system, improve the thickening property of the alkali-swellable thickener, and the obtained alkali-swellable thickener can be used in water-based coatings to reduce the post-thickening of the water-based coating to a certain extent. The inventors speculate that it is because the biological enzyme of the present invention can maintain the balance of components in the water-based coating, which helps to maintain the uniform dispersion of solid particles or dissolved substances in the water-based coating, thereby avoiding the post-thickening of the water-based coating.

[0014] The inventors also found that the addition of biological enzymes less than 0.5% or more than 2% will lead to a decrease in the thickening effect of the alkali swelling thickener. The inventors speculate that this is because when the content of the biological enzyme is low, some monomers cannot react completely, but when the content of the biological enzyme is too high, the relative molecular mass of the alkali swelling thickener may be reduced, or the biological enzyme may be inactivated or degraded due to the excessive content of the biological enzyme. It is also possible that the reaction is more intense due to the excessive content of the biological enzyme, and the segment distribution of the formed alkali swelling thickener is more complex, which reduces its thickening effect.

[0015] Preferably, the emulsifier comprises fatty alcohol ethoxylated polypropylene ether copolymer and / or a nonionic reactive emulsifier free of nonylphenol.

[0016] Preferably, the emulsifier is a combination of fatty alcohol ethoxylated polypropylene ether copolymer and a non-ionic reactive emulsifier free of nonylphenol, and the mass ratio of the fatty alcohol ethoxylated polypropylene ether copolymer and the non-ionic reactive emulsifier free of nonylphenol is (2-4):1.

[0017] Preferably, the EO additional mole number of the nonionic reactive emulsifier is 20-40, preferably 30.

[0018] The inventor unexpectedly discovered that when the EO additional mole number of the non-ionic reactive emulsifier is 20-40, preferably 30, it can not only improve the anti-settling effect of the alkali swelling thickener, but also improve the water resistance of the water-based coating when applied to the water-based coating. The inventor speculates that on the one hand, the non-ionic reactive emulsifier under this condition can be staggered with the fatty alcohol ethoxy polypropylene ether copolymer to be coated on the surface of the alkali swelling thickener structure. The alkali swelling thickener is used in the water-based coating and can more easily interact with the components in the water-based coating to avoid the sedimentation of the water-based coating. On the other hand, the non-ionic reactive emulsifier under this condition is more likely to be grafted with the fluorine-containing methacrylate monomer in the system under the action of the biological enzyme of the present invention, changing the structure of the alkali swelling thickener, improving the hydrophobicity of the alkali swelling thickener, and then improving the water resistance of the water-based coating.

[0019] The second aspect of the present invention provides a method for preparing an environmentally friendly alkali swelling thickener for coatings, comprising the following steps: S1. Mix half of the emulsifier, half of the biological enzyme and half of the deionized water, and then add the bio-based methacrylate monomer and the acrylic acid monomer to obtain a pre-emulsion; S2. Evenly mix the remaining emulsifier, biological enzyme and deionized water, heat to 30-40°C, add half of the pre-emulsion, and keep warm for 30-50 minutes to obtain the seed emulsion; S3. Add the remaining pre-emulsified liquid dropwise to the seed emulsion, control the adding time to be 2-3 hours, and keep warm at 30-40° C. for 1-2 hours after the adding is completed to obtain the alkali swelling thickener.

[0020] Beneficial Effects

[0021] 1. When hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate are introduced in a mass ratio of 0.5-1.5:1-1.5 in the present invention, and the obtained alkali swelling thickener is used in water-based coatings in combination with acrylate monomers and bio-based methacrylate monomers, the water-based coatings can have good leveling properties and avoid the reduction of the gloss of the water-based coatings.

[0022] 2. When the biological enzyme of the present invention is a mixture of Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B, it can synergistically initiate the polymerization reaction of monomers in the system, improve the thickening property of the alkali-swellable thickener, and the obtained alkali-swellable thickener can reduce the post-thickening of the water-based coating to a certain extent after being used in the water-based coating.

[0023] 3. The present invention adopts a specific amount of added biological enzyme to avoid the decrease of the thickening effect of the alkali swelling thickener.

[0024] 4. In the present invention, when the EO addition molar number of the nonionic reactive emulsifier is 20-40, preferably 30, it can not only improve the anti-settling effect of the alkali swelling thickener, but also improve the water resistance of the water-based coating when used in the water-based coating. DETAILED DESCRIPTION

[0025] In order to better explain the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the examples in the embodiments of the present invention. The embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other implementation methods obtained by those skilled in the art without making creative work are within the scope of protection of the present invention. The experimental methods in the following embodiments, unless otherwise specified, are conventional methods, and the materials, reagents, etc. used in the following embodiments, unless otherwise specified, can be obtained from commercial channels.

[0026] Raw materials used in the embodiments of the present invention: Hexafluorobutyl methacrylate CAS number: 36405-47-7; Dodecafluoroheptyl methacrylate CAS number: 2261-99-6; Pseudomonas cepacia lipase was purchased from Hangzhou Chuangke Biotechnology Co., Ltd.; Superoxide dismutase was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; Candida antarctica lipase B was purchased from Guangzhou Weber Technology Co., Ltd.; Tridecyl acrylate CAS number: 3076-04-8; Hexadecyl acrylate CAS number: 13402-02-3; Heptadecyl methacrylate was purchased from Evonik, model: Terra C17,4-MA; Isobornyl methacrylate was purchased from Evonik, model: Terra IBOMA; Fatty alcohol ethoxylated polypropylene ether copolymer was purchased from Hai'an Petrochemical Plant, Jiangsu Province, model: MOA-9.

[0027] Example 1

[0028] An environmentally friendly alkali swelling thickener for coatings, comprising the following raw materials by mass percentage: 20% acrylate monomer, 8% bio-based methacrylate monomer, 3% fluorine-containing methacrylate monomer, 3% emulsifier, 1% biological enzyme and the balance deionized water; The fluorine-containing methacrylate monomer includes hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate; the mass ratio of hexafluorobutyl methacrylate to dodecafluoroheptyl methacrylate is 1:1.2; The biological enzyme comprises a mixture of Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B, wherein the mass ratio of the Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B is 2:5:1.

[0029] The acrylic acid ester monomer comprises tridecyl acrylate and hexadecyl acrylate; the mass ratio of tridecyl acrylate to hexadecyl acrylate is 5:1; The bio-based methacrylate includes heptadecanyl methacrylate and isobornyl methacrylate; the mass ratio of heptadecanyl methacrylate to isobornyl methacrylate is 2:2.

[0030] The emulsifier is a combination of a fatty alcohol ethoxylated polypropylene ether copolymer and a non-ionic reactive emulsifier free of nonylphenol, and the mass ratio of the fatty alcohol ethoxylated polypropylene ether copolymer to the non-ionic reactive emulsifier free of nonylphenol is 3:1.

[0031] The nonionic reactive emulsifier has an EO addition mole number of 30 and is purchased from Nanjing Qinghai Trading Co., Ltd., model: ER-30.

[0032] A method for preparing an environmentally friendly alkali swelling thickener for coatings comprises the following steps: S1. Mix half of the emulsifier, half of the biological enzyme and half of the deionized water, and then add the bio-based methacrylate monomer and the acrylic acid monomer to obtain a pre-emulsion; S2, mix the remaining emulsifier, biological enzyme and deionized water evenly, heat to 35°C, add half of the pre-emulsion, and keep warm for 40 minutes to obtain the seed emulsion; S3. Add the remaining pre-emulsified liquid dropwise to the seed emulsion, control the dropping time to be 2 hours, and keep warm at 35° C. for 2 hours after the dropping is completed to obtain the alkali swelling thickener.

[0033] Example 2

[0034] The difference from Example 1 is that the environmentally friendly alkali swelling thickener for coating includes the following raw materials, by mass percentage: 15% acrylate monomer, 5% bio-based methacrylate monomer, 1% fluorine-containing methacrylate monomer, 1% emulsifier, 0.5% biological enzyme and the balance deionized water; the rest are the same.

[0035] Example 3

[0036] The difference from Example 1 is that the environmentally friendly alkali swelling thickener for coating includes the following raw materials, by mass percentage: 25% acrylate monomer, 10% bio-based methacrylate monomer, 5% fluorine-containing methacrylate monomer, 5% emulsifier, 2% biological enzyme and the balance deionized water; the rest are the same.

[0037] Comparative Example 1 The difference from Example 1 is that the fluorine-containing methacrylate monomer is hexafluorobutyl methacrylate, and the rest are the same.

[0038] Comparative Example 2 The difference from Example 1 is that the fluorine-containing methacrylate monomer is dodecafluoroheptyl methacrylate, and the rest is the same.

[0039] Comparative Example 3 The difference from Example 1 is that the mass ratio of hexafluorobutyl methacrylate to dodecafluoroheptyl methacrylate is 2:0.5, and the rest are the same.

[0040] Comparative Example 4 The difference from Example 1 is that the Pseudomonas cepacia lipase is replaced with superoxide dismutase of equal mass, and the rest is the same.

[0041] Comparative Example 5 The difference from Example 1 is that superoxide dismutase is replaced by horseradish peroxidase of equal mass purchased from Sangon Biotech (Shanghai) Co., Ltd.; the rest are the same.

[0042] Comparative Example 6 The difference from Example 1 is that the antarctic Candida lipase B is replaced by Pseudomonas cepacia lipase of the same mass, and the rest is the same.

[0043] Comparative Example 7 The difference from Example 1 is that the biological enzyme is 0.3%, and the rest is the same.

[0044] Comparative Example 8 The difference from Example 1 is that the biological enzyme is 2.5%, and the rest is the same.

[0045] Comparative Example 9 The difference from Example 1 is that the EO additional mole number of the non-ionic reactive emulsifier is 10, purchased from Nanjing Qinghai Trading Co., Ltd., model: ER-10, and the rest are the same.

[0046] Test Case The alkali swelling thickeners of Examples 1-3 and Comparative Examples 1-9 were applied to water-based coatings. The formula of the water-based coatings was based on the Chinese patent publication number CN 117510743 A: acrylic resin RA1260 and polyurethane resin RU2301 of Sichuan Dawei Technology Co., Ltd. were compounded in a mass ratio of 2:1, and then the pH of the mixed resin was adjusted to 8.0 with ammonia water, and 0.5% (relative to the total mass of the mixed resin) of the alkali swelling thickeners of the embodiments of the present invention and the comparative examples were slowly added under stirring at about 200 rpm.

[0047] The following tests were performed on the water-based coatings containing the alkali-swellable thickeners of Examples 1-3 and Comparative Examples 1-9 of the present invention: 1. Anti-settling performance: Place it in a 25℃ environment for 30 days and observe whether stratification occurs. If so, it is considered unqualified. The results are shown in Table 1.

[0048] 2. Thickening performance: The viscosity was measured at 25°C and 3#60rpm using a viscometer. The results are shown in Table 1.

[0049] 3. Post-thickening performance: After being placed in an environment of 25°C for 30 days, calculate the change in viscosity at 3#60rpm.

[0050] 4. Glossiness and water resistance: tested in accordance with GB / T 23999-2009. The results are shown in Table 1.

[0051] Table 1 Performance test results of water-based coatings containing alkali-swellable thickeners of Examples 1-3 and Comparative Examples 1-9

[0052] It can be seen from Table 1 that the water-based coatings containing the alkali-swellable thickeners of Examples 1-3 have no stratification phenomenon, have a higher viscosity, can avoid post-thickening of the water-based coating, and improve the gloss and water resistance of the water-based coating.

[0053] The alkali-swellable thickener of Comparative Example 1 contains only hexafluorobutyl methacrylate, the alkali-swellable thickener of Comparative Example 2 contains only dodecafluoroheptyl methacrylate, and the alkali-swellable thickener of Comparative Example 3 contains hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate in a mass ratio not within the range of 0.5-1.5:1-1.5, resulting in significantly deteriorated gloss and water resistance of the water-based coatings containing the alkali-swellable thickeners of Comparative Examples 1-3.

[0054] Since the alkali swelling thickener of Comparative Example 4 replaces the Pseudomonas cepacia lipase with an equal mass of superoxide dismutase, the superoxide dismutase of Comparative Example 5 replaces the horseradish peroxidase of an equal mass, and the Antarctic Candida lipase B of Comparative Example 6 replaces the Pseudomonas cepacia lipase with an equal mass of Pseudomonas cepacia lipase, the component balance of the water-based coating cannot be maintained, thereby causing the stability, viscosity and post-thickening performance of the water-based coating containing the alkali swelling thickeners of Comparative Examples 4-6 to be significantly deteriorated.

[0055] Since the amount of biological enzyme added in the alkali swelling thickener of Comparative Examples 7-8 is not in the range of 0.2-5%, the stability, viscosity and post-thickening performance of the water-based coating containing the alkali swelling thickener of Comparative Examples 7-8 are significantly deteriorated. In particular, the water resistance of the water-based coating containing the alkali swelling thickener of Comparative Example 7 is significantly deteriorated.

[0056] In Comparative Example 9, since the EO addition molar number of the nonionic reactive emulsifier is less than 20, the stability of the water-based coating containing the alkali-swellable thickener of Comparative Example 7-8 is significantly reduced, and the water resistance of the water-based coating is significantly deteriorated.

[0057] The above description is only a specific embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent transformation made by the present invention, or directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the present invention.

Claims

1. An environmentally friendly alkali swelling thickener for coatings, characterized in that: The raw materials include, by mass percentage, 15-25% of acrylate monomer, 5-10% of bio-based methacrylate monomer, 1-5% of fluorine-containing methacrylate monomer, 1-5% of emulsifier, 0.5-2% of biological enzyme and the balance of deionized water; The fluorine-containing methacrylate monomer includes hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate; the mass ratio of hexafluorobutyl methacrylate to dodecafluoroheptyl methacrylate is 0.5-1.5:1-1.5; The biological enzyme comprises a mixture of Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B, wherein the mass ratio of the Pseudomonas cepacia lipase, superoxide dismutase and Candida antarctica lipase B is 2-3:4-6:

1.

2. The environmentally friendly alkali swelling thickener for coatings according to claim 1, characterized in that: The acrylate monomers include tridecyl acrylate and hexadecyl acrylate.

3. The environmentally friendly alkali swelling thickener for coatings according to claim 2, characterized in that: The mass ratio of tridecyl acrylate to hexadecyl acrylate is 4-6:

1.

4. The environmentally friendly alkali swelling thickener for coatings according to claim 3, characterized in that: The bio-based methacrylates include heptadecyl methacrylate and isobornyl methacrylate.

5. The environmentally friendly alkali swelling thickener for coatings according to claim 4, characterized in that: The mass ratio of heptadecyl methacrylate to isobornyl methacrylate is 2:1-3.

6. The environmentally friendly alkali swelling thickener for coatings according to claim 1, characterized in that: The emulsifier includes fatty alcohol ethoxylated polypropylene ether copolymer and / or a nonionic reactive emulsifier free of nonylphenol.

7. The environmentally friendly alkali swelling thickener for coatings according to claim 6, characterized in that: The emulsifier is a combination of a fatty alcohol ethoxylated polypropylene ether copolymer and a non-ionic reactive emulsifier free of nonylphenol, and the mass ratio of the fatty alcohol ethoxylated polypropylene ether copolymer to the non-ionic reactive emulsifier free of nonylphenol is (2-4):

1.

8. The environmentally friendly alkali swelling thickener for coatings according to claim 7, characterized in that: The EO additional mole number of the nonionic reactive emulsifier is 20-40.

9. The environmentally friendly alkali swelling thickener for coatings according to claim 8, characterized in that: The EO additional mole number of the nonionic reactive emulsifier is 30.

10. A method for preparing the environmentally friendly alkali swelling thickener for coatings according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Mix half of the emulsifier, half of the biological enzyme and half of the deionized water, and then add the bio-based methacrylate monomer and the acrylic acid monomer to obtain a pre-emulsion; S2. Evenly mix the remaining emulsifier, biological enzyme and deionized water, heat to 30-40°C, add half of the pre-emulsion, and keep warm for 30-50 minutes to obtain the seed emulsion; S3. Add the remaining pre-emulsified liquid dropwise to the seed emulsion, control the adding time to be 2-3 hours, and keep warm at 30-40° C. for 1-2 hours after the adding is completed to obtain the alkali swelling thickener.

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