Waterborne acrylic coating and preparation method thereof
By preparing waterproof modifiers containing specific functional groups and combining with other additives, the problem of insufficient water resistance and UV resistance of aqueous acrylic coatings is solved, and efficient waterproofing and UV resistance is achieved, which is suitable for long-term use of building surfaces.
Patent Information
- Application Number
- CN202510535519.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-27
- Publication Date
- 2025-06-24
Smart Images
Figure BDA0005377873450000031 
Figure BDA0005377873450000032 
Figure BDA0005377873450000081
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of acrylic coatings, and specifically, relates to an aqueous acrylic coating and a preparation method thereof. Background Art
[0002] Acrylic resin coatings are thermoplastic or thermosetting resin coatings prepared from acrylic resins obtained by copolymerizing (meth)acrylate and styrene as the main components with other acrylate esters. With the increasing global awareness of environmental protection and the strict restrictions on the emissions of volatile organic compounds (VOCs) by governments of various countries, traditional solvent-based coatings have been gradually phased out by the market due to their high VOC content. Aqueous acrylic coatings, with their low VOC emissions, excellent weather resistance, good adhesion and construction performance, are widely used in the construction field due to their excellent properties. However, although aqueous acrylic coatings have significant advantages in terms of environmental protection, the optimization of their performance and technological improvement are still the focus of current research.
[0003] The ester groups contained in acrylic resin molecules make the formed coating have certain water permeability. Especially when exposed to sunlight, wind, rain and acidic substances, the ester groups are prone to hydrolysis reactions, resulting in a decline in the film performance. Therefore, the water resistance of acrylic resins is poor. From the perspective of building waterproofing requirements, buildings will inevitably be affected by rainwater penetration, groundwater erosion and moisture diffusion during long-term use. Due to the poor water resistance of acrylic resins, this will not only lead to the deterioration of the wall structure, but also may cause problems such as mold growth and wall peeling, seriously affecting the service life and aesthetics of the building. Moreover, most of them are exposed to sunlight for a long time and affected by ultraviolet rays, which will lead to a decline in the performance of the surface coating. To sum up, there is an urgent need to invent an aqueous acrylic waterproof coating with anti-ultraviolet performance to meet the higher requirements in the technical field of acrylic coatings. Summary of the Invention
[0004] The purpose of the present invention is to overcome the defects of the prior art and provide an aqueous acrylic coating and a preparation method thereof.
[0005] The purpose of the present invention can be achieved by the following technical solutions:
[0006] A preparation method of an aqueous acrylic coating includes the following steps:
[0007] Step 1: Mix an emulsifier and deionized water in a reaction kettle. After stirring evenly, methyl methacrylate, butyl acrylate and methacrylic acid are added in sequence, and a pre-emulsion is obtained under high-speed stirring;
[0008] Step 2: Continue to add an initiator and a waterproof modifier to the reaction kettle, stir and react at 70 - 80 °C for 2 - 3 h. After the reaction is completed, add an antifoaming agent and continue to stir for 30 min to obtain a waterborne acrylic coating.
[0009] Further, the raw materials are as follows by weight parts: 5 - 8 parts of emulsifier, 100 - 120 parts of deionized water, 22 - 36 parts of methyl methacrylate, 19 - 27 parts of butyl acrylate, 16 - 26 parts of methacrylic acid, 0.2 - 0.4 parts of initiator, 4 - 12 parts of waterproof modifier, 0.5 - 1.1 parts of antifoaming agent.
[0010] Further, the rotation speed of the high - speed stirring is 1000 - 1200 r / min and the time is 30 min.
[0011] Further, the emulsifier is one of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate.
[0012] Further, the initiator is one of benzoyl peroxide, ammonium persulfate and di - tert - butyl peroxide.
[0013] Further, the waterproof modifier is prepared through the following steps:
[0014] Step 1: Weigh methacrylic acid and 1,3 - bis(aminopropyl)tetramethyldisiloxane as reaction raw materials, and add them together with N,N - dimethylformamide into a three - necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing evenly, add diisopropylcarbodiimide as a dehydrating agent to the system. Place the reaction device in a 50 °C constant temperature water bath and continuously react for 3 h. After the reaction is completed, filter, remove the solvent by vacuum distillation, wash the product with anhydrous ethanol multiple times, and finally obtain the target product 1 through vacuum drying.
[0015] The reaction principle of Step 1 is as follows: Under the catalysis of diisopropylcarbodiimide, the amino group in the molecule of 1,3 - bis(aminopropyl)tetramethyldisiloxane reacts with the carboxyl group on methacrylic acid to undergo an amidation reaction. By adjusting the molar ratio of the two to be close to 1:1 (1,3 - bis(aminopropyl)tetramethyldisiloxane is slightly in excess), it can ensure that only one amino group in the molecule of 1,3 - bis(aminopropyl)tetramethyldisiloxane undergoes an amidation reaction. The reaction formula is as follows:
[0016]
[0017] Step 2: Weigh 2-aminobenzotriazole and trimesic acid as reaction raw materials, add them together with N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing, add N,N'-diisopropylcarbodiimide to the system. Place the reaction device in a constant temperature water bath at 60 °C and react continuously for 5 h. After the reaction is completed, filter, remove part of the solvent by reduced pressure distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 5:2). Rotate and evaporate to remove the eluent to obtain the target product 2;
[0018] The reaction principle of Step 2 is as follows: Under the catalysis of N,N'-diisopropylcarbodiimide, the amino group in the 2-aminobenzotriazole molecule reacts with the carboxyl group on the trimesic acid to undergo an amidation reaction. By adjusting the molar ratio of the two to be close to 2:1 (trimesic acid is slightly in excess), only two carboxyl groups in the trimesic acid molecule undergo an amidation reaction; the reaction formula is as follows:
[0019]
[0020] Step 3: Weigh the target product 1 and the target product 2 as reaction raw materials, add them together with N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing, add dicyclohexylcarbodiimide to the system. Place the reaction device in a constant temperature water bath at 65 °C and react continuously for 6 h. After the reaction is completed, filter, remove part of the solvent by reduced pressure distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 5:1). Rotate and evaporate to remove the eluent to obtain the waterproof modifier;
[0021] The reaction principle of Step 3 is as follows: Under the catalysis of dicyclohexylcarbodiimide, the amino group in the target product 1 reacts with the carboxyl group on the target product 2 to undergo an amidation reaction.
[0022] Furthermore, in Step 1, the dosage ratio of methacrylic acid, 1,3-bis(aminopropyl)tetramethyldisiloxane, N,N-dimethylformamide, and N,N'-diisopropylcarbodiimide is 8.6 g:25.1 g:100 mL:12.6 g.
[0023] Furthermore, in Step 2, the dosage ratio of 2-aminobenzotriazole, trimesic acid, N,N-dimethylformamide, and N,N'-diisopropylcarbodiimide is 26.8 g:26.3 g:150 mL:25.2 g.
[0024] Furthermore, in Step 3, the dosage ratio of the target product 1, the target product 2, N,N-dimethylformamide, and dicyclohexylcarbodiimide is 31.6 g:44.2 g:150 mL:20.6 g.
[0025] A waterproof modifier is prepared through a three-step amidation reaction. The preparation principle is simple. One end of the obtained waterproof modifier molecule contains an unsaturated carbon-carbon double bond, which can participate in the polymerization reaction under the action of an initiator, improving the migration resistance of the small-molecule waterproof modifier. In addition, the waterproof modifier molecule also contains a benzene ring and a silicon-oxygen bond. The benzene ring can improve the waterproof performance of the matrix to a certain extent. The silicon atom in the silicon-oxygen bond has a relatively low electronegativity, and the bond formed with the oxygen atom has a weak polarity and is not easily interacted with water (strong polarity). Moreover, the silicon-oxygen bond has a relatively long bond length and high molecular chain flexibility, and can spontaneously arrange into a hydrophobic surface, reducing water molecule adsorption and further improving the waterproof performance of the matrix. Finally, the obtained waterproof modifier molecule also contains two benzotriazole groups. As an efficient ultraviolet absorber, it can effectively absorb ultraviolet energy and convert it into heat energy through a specific chemical structure and photophysical mechanism, thereby protecting the matrix from damage by ultraviolet radiation and improving the ultraviolet resistance of the matrix.
[0026] Advantages of the present invention:
[0027] 1. The coating uses water as a dispersion medium, significantly reducing the emission of volatile organic compounds and meeting environmental protection requirements;
[0028] 2. The preparation of the waterproof modifier is completed through a three-step amidation reaction. The reaction conditions are mild, the principle is clear, and it is easy to industrialize;
[0029] 3. The obtained waterproof modifier molecule contains multiple functional groups, which can greatly improve the waterproof performance and ultraviolet resistance of the coating, and the performance is stable;
[0030] 4. The coating is particularly suitable for building surfaces that are long-term exposed to the outdoors or in humid environments, and can effectively prevent problems such as wall deterioration and wall peeling;
[0031] Therefore, the coating prepared by the present invention has stable and efficient waterproof performance and ultraviolet resistance, and is environmentally friendly, and has important application value in the field of acrylic coating technology. Specific embodiments
[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0033] Example 1
[0034] Prepare a waterproof modifier:
[0035] Step 1: Weigh 8.6 g of methacrylic acid and 25.1 g of 1,3-bis(aminopropyl)tetramethyldisiloxane as reaction raw materials, and add them together with 100 mL of N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing evenly, add 12.6 g of diisopropylcarbodiimide as a dehydrating agent to the system. Place the reaction device in a constant temperature water bath at 50 °C and react continuously for 3 h. After the reaction is completed, filter, remove the solvent by vacuum distillation, wash the product with absolute ethanol multiple times, and finally obtain the target product 1 through vacuum drying;
[0036] Step 2: Weigh 26.8 g of 2-aminobenzotriazole and 26.3 g of trimesic acid as reaction raw materials, and add them together with 150 mL of N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing, add 25.2 g of diisopropylcarbodiimide to the system. Place the reaction device in a constant temperature water bath at 60 °C and react continuously for 5 h. After the reaction is completed, filter, remove part of the solvent by vacuum distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 5:2). Rotate and evaporate to remove the eluent to obtain the target product 2;
[0037] Step 3: Weigh 31.6 g of target product 1 and 44.2 g of target product 2 as reaction raw materials, and add them together with 150 mL of N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing, add 20.6 g of dicyclohexylcarbodiimide to the system. Place the reaction device in a constant temperature water bath at 65 °C and react continuously for 6 h. After the reaction is completed, filter, remove part of the solvent by vacuum distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 5:1). Rotate and evaporate to remove the eluent to obtain the waterproof modifier.
[0038] Example 2
[0039] Preparation of waterproof modifier:
[0040] Step 1: Weigh 17.2 g of methacrylic acid and 50.2 g of 1,3-bis(aminopropyl)tetramethyldisiloxane as reaction raw materials, and add them together with 200 mL of N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing evenly, add 25.2 g of diisopropylcarbodiimide as a dehydrating agent to the system. Place the reaction device in a constant temperature water bath at 50 °C and react continuously for 3 h. After the reaction is completed, filter, remove the solvent by vacuum distillation, wash the product with absolute ethanol multiple times, and finally obtain the target product 1 through vacuum drying;
[0041] Step 2: Weigh 53.6 g of 2-aminobenzotriazole and 52.6 g of benzene-1,3,5-tricarboxylic acid as reaction raw materials, and add them together with 300 mL of N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing, add 50.4 g of diisopropylcarbodiimide to the system. Place the reaction device in a constant temperature water bath at 60 °C and react continuously for 5 h. After the reaction is completed, filter, remove part of the solvent by vacuum distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 5:2). Rotate and evaporate to remove the eluent to obtain the target product 2;
[0042] Step 3: Weigh 63.2 g of target product 1 and 88.4 g of target product 2 as reaction raw materials, and add them together with 300 mL of N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. After stirring and mixing, add 41.2 g of dicyclohexylcarbodiimide to the system. Place the reaction device in a constant temperature water bath at 65 °C and react continuously for 6 h. After the reaction is completed, filter, remove part of the solvent by vacuum distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 5:1). Rotate and evaporate to remove the eluent to obtain the waterproof modifier.
[0043] Example 3
[0044] Step 1: Mix 5 g of sodium dodecyl sulfate with 100 g of deionized water in a reaction kettle. After stirring evenly, add 22 g of methyl methacrylate, 19 g of butyl acrylate and 16 g of methacrylic acid in sequence. Stir at a high speed of 1000 r / min for 30 min to obtain a pre-emulsion;
[0045] Step 2: Continue to add 0.2 g of ammonium persulfate and 4 g of the waterproof modifier prepared in Example 1 to the reaction kettle, stir and react at 70 °C for 2 h. After the reaction is completed, add 0.5 g of silicone defoamer (BYK-028), and continue to stir for 30 min to obtain a waterborne acrylic coating.
[0046] Example 4
[0047] Step 1: Mix 7 g of sodium dodecylbenzenesulfonate with 110 g of deionized water in a reaction kettle. After stirring evenly, add 29 g of methyl methacrylate, 23 g of butyl acrylate and 21 g of methacrylic acid in sequence. Stir at a high speed of 1100 r / min for 30 min to obtain a pre-emulsion;
[0048] Step 2: Continue to add 0.3 g of benzoyl peroxide and 8 g of the waterproof modifier prepared in Example 2 to the reaction kettle, stir and react at 80 °C for 3 h. After the reaction is completed, add 0.8 g of silicone defoamer (BYK-028), and continue to stir for 30 min to obtain a waterborne acrylic coating.
[0049] Example 5
[0050] Step 1: In a reaction kettle, 8 g of sodium dodecylbenzenesulfonate is mixed with 120 g of deionized water. After stirring evenly, 36 g of methyl methacrylate, 27 g of butyl acrylate, and 26 g of methacrylic acid are added in sequence. At a rotation speed of 1200 r / min, high-speed stirring is carried out for 30 min to obtain a pre-emulsion.
[0051] Step 2: Continue to add 0.4 g of di-tert-butyl peroxide and 12 g of the waterproof modifier prepared in Example 2 to the reaction kettle. Stir and react at 80 °C for 3 h. After the reaction is completed, 1.1 g of silicone defoamer (BYK-028) is added, and stirring is continued for 30 min to obtain a waterborne acrylic coating.
[0052] Comparative Example 1
[0053] During the preparation process of Example 5, only the waterproof modifier is replaced with an equal amount of commercially available silicone waterproof agent, and the other conditions remain unchanged to prepare a coating.
[0054] Comparative Example 2
[0055] Use a commercially available waterborne acrylic coating.
[0056] Perform the following performance tests on Examples 3, 4, 5 and Comparative Examples 1 and 2:
[0057] The adhesion is measured according to the national standard GB / T 1720 Determination Method for Adhesion of Paint Films;
[0058] The water resistance of the applied sample is measured according to the national standard GB / T 1733-1993 Determination Method for Water Resistance of Paint Films;
[0059] The ultraviolet resistance is measured according to the national standard GB / T 1865-2009 and rated according to the GB / T 1766 standard;
[0060] Examples 3, 4, 5 and Comparative Example 1 are left standing in a light-shielded environment for 300 days, and the water resistance (GB / T 1733-1993) is measured;
[0061] The measurement results are shown in the following table:
[0062]
[0063] As can be seen from the above table, the coatings prepared in the examples of the present invention have higher waterproof performance and ultraviolet resistance than the comparative examples, and the performance is stable, which has important application value in the technical field of acrylic coatings.
[0064] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.
[0065] The above content is only an example and illustration of the present invention. Those skilled in the art to which the present technology pertains may make various modifications or supplements to the described specific embodiments or use similar ways for substitution, all of which should fall within the protection scope of the present invention.
Claims
1. A method for preparing a water-based acrylic paint, characterized in that: The following steps are involved: Step 1: In a reaction kettle, an emulsifier and deionized water are mixed, and after stirring evenly, methyl methacrylate, butyl acrylate and methacrylic acid are added in sequence, and a pre-emulsion is obtained under high-speed stirring; Step 2: Continue to add the initiator and the waterproof modifier into the reactor, stir to react, add the defoamer, continue to stir, and obtain the water-based acrylic paint.
2. The method for preparing a water-based acrylic paint according to claim 1, characterized in that: The waterproof modifier is prepared by the following steps: Step 1, methacrylic acid, 1,3-bis(aminopropyl)tetramethyldisiloxane and N,N-dimethylformamide were added into a flask, stirred and mixed, and then diisopropylcarbodiimide was added, and the mixture was reacted at 50° C. for 3 h. The reaction was completed to obtain the target product 1; Step 2, add 2-aminobenzotriazole, trimesic acid and N,N-dimethylformamide into a flask, stir and mix, then add diisopropylcarbodiimide, react at 60° C. for 5 h, and the reaction is completed to obtain the target product 2; Step 3: Add the target product 1, the target product 2 and N,N-dimethylformamide into a flask, stir and mix, then add dicyclohexylcarbodiimide, and react at 65° C. for 6 hours. The reaction is completed to obtain a waterproof modifier.
3. The method for preparing a water-based acrylic paint according to claim 2, characterized in that: In step 1, the ratio of methacrylic acid, 1,3-bis(aminopropyl)tetramethyldisiloxane, N,N-dimethylformamide, and diisopropylcarbodiimide is 8.6 g:25.1 g:100 mL:12.6 g.
4. The method for preparing a water-based acrylic paint according to claim 2, characterized in that: In step 2, the ratio of 2-aminobenzotriazole, trimesic acid, N,N-dimethylformamide and diisopropylcarbodiimide is 26.8 g:26.3 g:150 mL:25.2 g.
5. The method for preparing a water-based acrylic paint according to claim 2, characterized in that: In step 3, the ratio of the amount of target product 1, target product 2, N,N-dimethylformamide and dicyclohexylcarbodiimide used is 31.6 g:44.2 g:150 mL:20.6 g.
6. The method for preparing a water-based acrylic paint according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 5-8 parts of emulsifier, 100-120 parts of deionized water, 22-36 parts of methyl methacrylate, 19-27 parts of butyl acrylate, 16-26 parts of methacrylic acid, 0.2-0.4 parts of initiator, 4-12 parts of waterproof modifier, and 0.5-1.1 parts of defoamer.
7. The method for preparing a water-based acrylic paint according to claim 1, characterized in that: The high-speed stirring has a rotation speed of 1000-1200 r / min and a time of 30 min.
8. The method for preparing a water-based acrylic paint according to claim 1, characterized in that: The emulsifier is one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.
9. The method for preparing a water-based acrylic paint according to claim 1, characterized in that: The initiator is one of benzoyl peroxide, ammonium persulfate and di-tert-butyl peroxide.
10. A water-based acrylic paint, characterized in that: Prepared according to the method according to any one of claims 1 to 9.