A water-based paint and a method for preparing the same

Abstract

This invention discloses a water-based paint and its preparation method. The water-based paint consists of two components, A and B. Component A is mainly composed of 32-45 parts of solvent-based hydroxyl acrylic resin as the film-forming agent, compounded with a drier, castor oil polyoxyethylene ether, acetylsalicylic acid glycol and mineral oil-based compound defoamer, reinforcing filler, anionic leveling agent, regulator, and deionized water. Component B includes an isocyanate compound. The mass ratio of components A to B is 100:15-25. In the preparation process, the resin, drier, and emulsifier are first mixed at low speed, followed by stepwise water addition for phase inversion and gradient stirring. The additives are added sequentially to obtain component A, and then the isocyanate is dissolved to obtain component B. This invention uses water as the main solvent, has a low VOC content, and uses castor oil polyoxyethylene ether to both emulsify and form films. The components are synergistically adapted, and the paint film is free of pinholes and craters. It has excellent hardness, resistance to media, and mechanical properties, which solves the problems of poor performance and many coating defects of existing water-based wood coatings. It is also convenient to apply and has a lower cost.

Description

Technical Field

[0001] This invention relates to the field of coatings, and in particular to a water-based paint and its preparation method. Background Technology

[0002] In the traditional industrial coatings industry, oil-based coatings have long held a dominant position in application, especially in the wood products industry, due to their good physical properties, excellent surface effects, good application tolerance, and simple preparation and coating equipment. However, these coatings have a high content of volatile organic compounds (VOCs), which can lead to air pollution. With increasing attention to environmental protection, the coatings industry is moving towards environmentally friendly and low-emission directions. Therefore, the development of low-VOC water-based wood coatings has become an important direction for industry development.

[0003] Most commercially available water-based wood coatings are made by further processing acrylic emulsions or acrylic secondary dispersion emulsions. Compared with traditional oil-based wood coatings, they have disadvantages such as complex production processes, high prices, high requirements for construction environment and drying conditions, low solids content, poor filling of deep wood pores, poor film hardness, poor water resistance, and poor resistance to humid heat.

[0004] To address the performance and cost issues of waterborne wood coatings, new technological approaches are urgently needed for improvement. Solvent-based hydroxyl acrylic resins have long been preferred film-forming materials for paints. The hydroxyl groups on their resin chains can undergo cross-linking reactions with compounds containing isocyanate (-NCO) functional groups to form films with excellent physical properties such as weather resistance, high transparency, light color, good gloss and color retention, high hardness, and good chemical resistance. Although these resins contain hydroxyl groups, their overall hydrophilicity is very poor, making them difficult to use directly as film-forming materials for waterborne paints. Based on these characteristics, we attempted to directly emulsify and disperse hydroxyl acrylic resins by adding suitable emulsifiers to prepare waterborne coatings.

[0005] However, numerous experimental studies have found that most emulsifiers cause defects in the paint film when used for emulsifying hydroxyl acrylic resins. Typical problems include: wet film cratering, resulting in poor leveling; difficulty in degassing the wet film, causing air bubbles to fail to escape after drying, resulting in numerous pinhole-like defects in the dry film; residual hydrophilic groups in the paint film leading to poor water resistance; and emulsifier residue causing a decrease in hardness.

[0006] In view of this, the present invention proposes a water-based paint and its preparation method to solve the above problems. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the first objective of this invention is to provide a low-cost, high-performance water-based paint with low volatile organic compounds, which is environmentally friendly and has a uniform, high hardness, excellent water resistance, damp heat resistance and liquid resistance after curing.

[0008] To achieve the above objectives, the present invention provides a water-based paint comprising component A and component B, wherein the mass ratio of component A to component B is 100:15~25; component A comprises the following raw materials in parts by mass: 32-45 parts solvent-based hydroxyl acrylic resin, 0-0.04 parts drier, 1.8-2.5 parts castor oil polyoxyethylene ether, 0.5-1.5 parts defoamer, 0-40 parts reinforcing filler, 0.02-0.05 parts anionic leveling agent, 0-0.9 parts regulator, and 40-55 parts deionized water; component B comprises an isocyanate compound.

[0009] Preferably, the defoamer includes acetylenic diol defoamers and / or mineral oil-based defoamers.

[0010] Preferably, the mass ratio of the acetylenic diol defoamer to the mineral oil-based defoamer is 1-1.6:0.6-1.2.

[0011] Preferably, the solvent-based hydroxyl acrylic resin has a solid content of 60% to 80%, the hydroxyl content in the solid is 2% to 5%, and the hydroxyl acrylic resin is a low-grade ester.

[0012] Preferably, the regulator includes a pH adjuster and a thickener.

[0013] Preferably, the thickener is a polyurethane associative thickener, and the pH adjuster is 2-amino-2-methyl-1-propanol.

[0014] Preferably, the drying agent comprises an organotin compound and / or an organobismuth compound.

[0015] Preferably, the reinforcing filler includes one or more of glass powder, silica micro powder, and barium sulfate, or one or two of calcium carbonate and titanium dioxide.

[0016] Preferably, component B comprises the following raw materials in parts by weight: 70-100 parts isocyanate compound, 0-20 parts propylene glycol methyl ether acetate, wherein the isocyanate compound comprises diisocyanate and / or polyisocyanate, and the NCO content of the isocyanate compound is 20%-22%.

[0017] In view of the shortcomings of the prior art, the second objective of the present invention is to provide a preparation method capable of preparing the above-mentioned water-based paint.

[0018] A method for preparing a water-based paint includes the following steps:

[0019] (1) Add solvent-based hydroxyl acrylic resin, drying agent and castor oil polyoxyethylene ether to the dispersion tank in sequence and stir at low speed until uniform;

[0020] (2) Slowly add some deionized water while stirring.

[0021] (3) Slowly add pH adjuster, then add defoamer, reinforcing filler, anionic leveling agent, remaining deionized water and thickener in sequence, while stirring, and finally obtain water-based paint.

[0022] (4) Add propylene glycol methyl ether acetate to another dispersion tank, and then slowly add the isocyanate compound to the dispersion tank while stirring. Finally, the B component of the water-based paint is obtained.

[0023] Preferably, the stirring speed in steps (2) and (3) is greater than that in step (1), and the mass ratio of deionized water added in steps (2) and (3) is 1:1.4~2.5.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. Component A of this invention uses deionized water as the main solvent to disperse other substances in the waterborne paint, significantly reducing VOC emissions and lowering product costs. Simultaneously, the addition of castor oil polyoxyethylene ether as an emulsifier not only emulsifies the hydroxyl acrylic resin and its components with deionized water to form a uniform and stable coating system, improving the workability of the waterborne paint and facilitating the storage of component A, but also, because castor oil polyoxyethylene ether itself contains hydroxyl groups, it can react with isocyanate compounds to form a film, avoiding poor liquid resistance caused by emulsifier residue.

[0026] 2. The castor oil polyoxyethylene ether in component A is compounded with acetylsadiol defoamer and mineral oil-based defoamer, mainly to eliminate the foam generated by the addition of castor oil polyoxyethylene ether and the air bubbles generated during paint mixing and spraying.

[0027] 3. The water-based paint of the present invention uses hydroxyl acrylic resin with medium to high hydroxyl value as the main film-forming material, which ensures that there is a suitable ratio of hydroxyl groups to react with isocyanate compounds to form a film, and at the same time, it is combined with reinforcing fillers and other raw materials to form a paint film with good mechanical properties and weather resistance. Detailed Implementation

[0028] The following examples further illustrate the features and other related characteristics of the present invention in detail, to facilitate understanding by those skilled in the art:

[0029] An embodiment of the present invention provides a water-based paint, comprising component A and component B, wherein the mass ratio of component A to component B is 100:15~25. Component A comprises the following raw materials in parts by mass: 32-45 parts solvent-based hydroxyl acrylic resin, 0-0.04 parts drier, 1.8-2.5 parts castor oil polyoxyethylene ether, 0.5-1.5 parts defoamer, 0-40 parts filler, 0.02-0.05 parts anionic leveling agent, 0-0.9 parts regulator, and 40-55 parts deionized water; component B comprises an isocyanate compound.

[0030] Castor oil polyoxyethylene ether has a long-chain hydrocarbon structure derived from castor oil, with an HLB value of 14-16. It exhibits good compatibility with the oily hydroxyl acrylic resin and lower ester solvents used in this invention. Furthermore, the ether structure of the polyoxyethylene ether allows it to form hydrogen bonds with deionized water in the paint, demonstrating excellent hydrophilicity. Based on this amphiphilic molecular structure, the oily hydroxyl acrylic resin is uniformly dispersed in the aqueous medium to form a stable aqueous emulsion. This ensures that component A does not separate or precipitate during storage, and that the paint remains uniformly dispersed during application, laying the foundation for uniform film formation.

[0031] In some embodiments, the solvent-based hydroxyl acrylic resin has a solid content of 60% to 80%, and the hydroxyl content in the solid is 2% to 5%. This provides a suitable functional group ratio for the crosslinking reaction between the resin and the isocyanate compound, ensuring that the crosslinking reaction proceeds fully while avoiding the imbalance of paint film performance caused by excessive hydroxyl groups. This is the core structural basis for the excellent mechanical properties and weather resistance of the paint film. Simultaneously, the hydroxyl acrylic resin does not contain benzene rings, avoiding yellowing of the paint film caused by benzene ring oxidation.

[0032] The solvent is a lower ester, which may be one or a mixture of several of butyl acetate, butyl propionate, butyl acrylate, and methyl methacrylate. It has a similar chemical structure to hydroxyl acrylic resin and can disperse hydroxyl acrylic resin.

[0033] Because castor oil polyoxyethylene ether is a nonionic surfactant, it can generate foam, affecting the appearance of the cured paint film. Therefore, to suppress foam in water-based paints, defoamers are also formulated. To avoid affecting the compatibility of the various components of the water-based paint and to ensure defoaming effectiveness, in some embodiments, the defoamer includes acetylenic glycol defoamers and mineral oil-based defoamers. Acrylylene glycol defoamers are miscible with hydroxyl acrylic resin and water, promoting the migration and collapse of bubbles from the interior of the coating to the surface. Mineral oil-based defoamers have good compatibility with hydroxyl acrylic resin and high defoaming efficiency; the combination of the two achieves good defoaming and foam-suppressing effects.

[0034] In some embodiments, the regulator includes a pH adjuster and a thickener.

[0035] In some embodiments, the thickener is a polyurethane associative thickener, whose molecular structure contains hydrophobic and hydrophilic segments. It can form a reversible network structure with waterborne hydroxy acrylic emulsion and surfactants in the system through hydrophobic association, and has the characteristics of high thickening efficiency, good viscosity stability and not easily affected by pH.

[0036] The pH adjuster is 2-amino-2-methyl-1-propanol, which is an organic alcohol amine pH adjuster. It has the advantages of mildly adjusting the pH of the system, low volatility, low odor, and strong stability. It can stabilize the water-based paint system in a weakly alkaline range, neutralize acidic substances in the system, and improve the storage stability of hydroxy acrylic emulsion.

[0037] In some embodiments, the drying agent includes organotin compounds and / or organobismuth compounds to accelerate the crosslinking reaction between the hydroxy acrylic resin and the isocyanate compound in component B.

[0038] In some embodiments, the reinforcing filler of the transparent water-based paint includes one or more of glass powder, silica micro powder, and barium sulfate, and the mass ratio between the solvent-based hydroxyl acrylic resin and the reinforcing filler is 10-20:0-1, which increases the scratch resistance and filling properties of the paint film without affecting the transparency of the water-based paint.

[0039] In some embodiments, the reinforcing filler of the white water-based paint includes one or both of calcium carbonate and titanium dioxide. The mass ratio of the solvent-based hydroxyl acrylic resin to the pigments and fillers is 2-4:1-2, which increases the scratch resistance and filling properties of the paint film, while also providing hiding power for the water-based paint.

[0040] In some embodiments, component B comprises the following raw materials in parts by weight: 80-100 parts isocyanate compound and 0-20 parts propylene glycol methyl ether acetate. The NCO content is 20%-22%. The active isocyanate groups (-NCO) can efficiently undergo a cross-linking reaction with the hydroxyl groups (-OH) of the hydroxyl acrylic resin in component A to form a three-dimensional network structure, making the paint film dense and firm. Propylene glycol methyl ether acetate is well miscible with the isocyanate compound and can disperse the isocyanate compound.

[0041] In some embodiments, the isocyanate compound includes diisocyanates and / or polyisocyanates, such as polymethyl diisocyanate, isophorone diisocyanate (IPDI), and HDI trimer.

[0042] The essence of wet film pinholes is that when the paint spreads on the substrate surface, uneven surface tension causes the paint to shrink towards areas of low surface tension, forming sunken, pore-like defects. Leveling agents can effectively reduce the surface tension of water-based paints, preventing excessive local surface tension differences that lead to wet film pinholes.

[0043] In some embodiments, the anionic leveling agent may be OT-75PG, EDAPLAN® LA452 (Germany), ANJEKA7358A (Germany), or CFMOTO FS-63 (USA). Anionic leveling agents have good compatibility with water-based phases and high leveling efficiency, further reducing defects such as sagging, orange peel, and pinholes that occur during the application of water-based paints.

[0044] An embodiment of the present invention provides a method for preparing a water-based paint, comprising the following steps:

[0045] (1) Add solvent-based hydroxyl acrylic resin, drier, and castor oil polyoxyethylene ether to the dispersion tank and stir at low speed until homogeneous. The solvent-based hydroxyl acrylic resin, drier, and castor oil polyoxyethylene ether have good compatibility. Mix the three first, and keep stirring at low speed during the mixing process. Since castor oil polyoxyethylene ether itself is prone to foaming, low-speed stirring can reduce foam generation and lay the foundation for the subsequent defoamer to play its role.

[0046] (2) Slowly add some deionized water while stirring. This is the stage where the solvent-based resin transitions to the aqueous system. The stirring speed in step (2) is greater than that in step (1) to promote uniform dispersion of the aqueous phase and achieve phase transition stability of the system.

[0047] (3) Slowly add pH adjuster, then add defoamer, filler, anionic leveling agent, remaining deionized water and thickener in sequence, while stirring, and finally obtain water-based paint.

[0048] In some embodiments, the stirring speed in steps (2) and (3) is greater than that in step (1); the stirring speed in step (1) can be 200~500 r / min, and the stirring speed in steps (2) and (3) can be 500~1000 r / min.

[0049] The mass ratio of deionized water added in steps (2) and (3) is 1:1.4~2.5.

[0050] The deionized water added in step (2) serves as the initiating aqueous phase for phase inversion. It can gradually form a stable pre-emulsion with the solvent-based hydroxyl acrylic resin and castor oil polyoxyethylene ether under high-speed stirring, avoiding water-oil separation and phase inversion failure caused by adding a large amount of deionized water at once. This proportion of aqueous phase ensures a gentle and orderly phase inversion process, allowing the resin to be fully dispersed in the aqueous phase and forming a uniform emulsion system, providing a stable carrier for the subsequent addition of other components.

[0051] (4) Add propylene glycol methyl ether acetate to another dispersion tank, and then slowly add the isocyanate compound to the dispersion tank while stirring. Finally, the B component of the water-based paint is obtained.

[0052] Existing technologies, such as Chinese Patent Publication No. CN108864916A, disclose a high-hardness, wear-resistant water-based paint that uses a water-based hydroxyl acrylic emulsion as the base. However, the preparation process of existing acrylic resin emulsions is generally complex, resulting in high prices. Acrylic resin emulsions can be prepared by monomer polymerization. Monomer polymerization involves adding an emulsifier to water, slowly pouring a monomer mixture into it while stirring, and then stirring at high speed to prepare a pre-emulsion. Next, water and a buffer are added to a reaction vessel, the temperature is raised, and a small amount of pre-emulsion is added to react with an initiator to form latex seed particles. Then, the remaining pre-emulsion and initiator are added dropwise at a uniform rate, the polymerization reaction is carried out, the pH value is adjusted, and the mixture is filtered to obtain the acrylic emulsion. For example, Chinese Patent Publication No. CN112812212B discloses a hydroxyl acrylic resin emulsion and its preparation method, which is similar to the operation described above.

[0053] Compared to existing technologies, this invention uses a combination of oil-based hydroxyl acrylic resin and castor oil polyoxyethylene ether emulsifier to produce water-based paint. By optimizing the order of addition and simple stirring, a water-based paint with hydroxyl acrylic resin as the base can be obtained. The preparation method is relatively simple and the cost is low.

[0054] Example 1

[0055] Example 1 of the present invention provides a water-based paint, the preparation method of which includes the following steps:

[0056] (1) Add solvent-based hydroxy acrylic resin, drying agent and castor oil polyoxyethylene ether to the dispersion tank and stir for 10 minutes at a speed of 500 r / min.

[0057] (2) Slowly add deionized water 1 over 5 to 10 minutes, stirring at 800 r / min during the process, and then stir for another 10 minutes after adding the water.

[0058] (3) Slowly add the pH adjuster, then add the defoamer in sequence, and continue stirring for 20 minutes after adding all the defoamer. Then add the filler and stir at 1000 r / min for 10 to 40 minutes. The more filler there is, the longer the stirring time should be.

[0059] (4) Add half of the deionized water 2, stir at 800 r / min for 5 minutes, then add half of the thickener and continue stirring for 5 minutes, then add the anionic leveling agent and continue stirring for 15 minutes.

[0060] (5) Add the other half of the deionized water 2, stir at 600 r / min for 5 min, and finally add the remaining thickener to adjust the viscosity and stir for 5 min to obtain component A.

[0061] (6) Add propylene glycol methyl ether acetate to another dispersion tank, and then slowly add polymethyl diisocyanate to the dispersion tank while stirring. Finally, the B component of the water-based paint is obtained.

[0062] Examples 2-5 and Comparative Example 1 were prepared by modifying the raw material formulation according to Table 1 and following the preparation method of Example 1, yielding water-based paint components A and B of Examples 2-5 and Comparative Example 1. All raw material quantities in Table 1 are parts by mass. The anionic leveling agent was Kombu FS-63, and the organotin compound was dibutyltin dilaurate. The solvent-based hydroxyl acrylic resin contained 70% solids and 30% butyl acetate, with a hydroxyl content of 3% in the solids. The polymethyl diisocyanate was Costron 2655.

[0063] Comparative Example 1 is a water-based wood varnish prepared from a commercially available hydroxyl acrylic emulsion, obtained through the following steps:

[0064] (1) Add 80 parts of commercially available hydroxyl acrylic emulsion (40% solid content, 2.2% hydroxyl content) to a clean dispersion tank, then add 0.2 parts of defoamer and 0.5 parts of dispersant in sequence. Turn on the stirring device, control the speed to 800 r / min, and stir continuously for 10 minutes to ensure that the raw materials are initially mixed evenly and there is no obvious agglomeration or stratification.

[0065] (2) Reduce the stirring speed to 500 r / min, and slowly add 0.2 parts of pH adjuster (AMP-95) while stirring until the mixture is uniform.

[0066] (3) Increase the stirring speed to 1000r / min, and slowly add 3 parts of talc powder while stirring. Control the feeding speed to avoid dust flying and local clumping. After the feeding is completed, keep stirring at 1000r / min for 10-20 minutes to ensure that the talc powder is completely dispersed and uniform, and the system has no particle feel.

[0067] (4) Adjust the stirring speed back to 500 r / min, and slowly add 4 parts of film-forming aid 1 (DPNB and deionized water are mixed at a mass ratio of 1:1) while stirring. Add the materials at a uniform speed to ensure that the aid is fully dispersed. After the addition is completed, keep the stirring speed at 500 r / min until the system is uniform.

[0068] (5) Maintain a stirring speed of 500 r / min, and slowly add 4 parts of film-forming aid 2 (dipropylene glycol methyl ether and deionized water mixed at a mass ratio of 1:1) while stirring. After the addition is completed, continue stirring at a speed of 500 r / min until the system is uniform.

[0069] (6) Slowly add 2 parts of propylene glycol methyl ether. After the additive is completely added, continue stirring until the system is homogeneous.

[0070] (7) Increase the stirring speed to 800 r / min, add 0.5 parts of associative polyurethane thickener, and stir until the viscosity of the system is initially stable; then add 0.3 parts of leveling agent, and continue to stir evenly at 800 r / min to optimize the leveling performance of the paint.

[0071] (8) Maintain a stirring speed of 800 r / min, add 5.2 parts of deionized water while stirring, stir until the system is uniform, and adjust the basic consistency and application viscosity of the paint.

[0072] (9) Maintain a stirring speed of 800 r / min. Add 0-0.1 parts of associative polyurethane thickener according to the actual viscosity of the system. Observe the viscosity change while adding. After reaching the target viscosity, continue stirring for 5 minutes to ensure uniform thickening and system stability, and finally obtain the A component main paint.

[0073] (10) Take another clean dispersion tank, add 20 parts of propylene glycol methyl ether acetate (PMA), turn on low speed stirring, and then slowly add 80 parts of polyhexamethylene diisocyanate (NCO content 21%) curing agent into the dispersion tank. Keep the stirring gentle throughout the process to avoid the generation of bubbles. After the curing agent is completely added, stir evenly to obtain component B curing agent, and seal for later use.

[0074] Table 1 shows the water-based paint formulations for Examples 1-5.

[0075] project Example 1 Example 2 Example 3 Example 4 Example 5 Solvent-based hydroxyl acrylic resin 35 40 32 35 35 Organotin compounds 0.02 0.03 0.02 0.02 0.02 Castor oil polyoxyethylene ether 1.8 2.5 1.8 2 2 Deionized water 1 25 25 25 25 25 2-Amino-2-methyl-1-propanol 0.2 0.2 0.2 0.2 0.2 Alkyne diol defoamers 0.5 0.6 0.5 0.7 0 Mineral oil-based defoamers 0.2 0.25 0.2 0 0.3 glass powder 2 1 4 5 6 Silica micro powder 1 1 1 0 0 Anionic leveling agent 0.08 0.08 0.09 0.08 0.08 Associative polyurethane thickeners 0.7 0.6 0.7 0.8 0.8 Deionized water 2 31.82 36 40 31.82 31.82 Polymethyl diisocyanate 80 80 80 80 80 PMA 20 20 20 20 20

[0076] Apply the water-based paints from Examples 1-5 to the rubberwood board according to the following steps:

[0077] Step 1: Mix components A, B, and water in a mass ratio of 100:20:45. Apply the prepared paint evenly to the rubber board and let it dry for 24 hours in an environment with a temperature of 30℃, relative humidity of less than 50%, and slight air flow. Sand it smooth with 320-grit sandpaper.

[0078] Step 2: Mix component A, component B, and water in a mass ratio of 100:20:40, and spray the prepared paint solution evenly onto the board again. Allow it to dry for 24 hours in an environment with a temperature of 30℃, relative humidity of less than 50%, and slight airflow. Then, sand it smooth with 320-grit sandpaper.

[0079] Step 3: Mix component A, component B, and water in a mass ratio of 100:20:40, and spray the prepared paint solution evenly onto the board again. Allow it to dry for 24 hours in an environment with a temperature of 30℃, relative humidity of less than 50%, and slight airflow.

[0080] The application steps for the water-based paint in Comparative Example 1 are the same as those in Examples 1-5, but the mixing ratio of Comparative Example 1 is: Paint A: Hardener B: Water = 100:15:15.

[0081] During the coating process, observe whether pinholes or uneven coating occur.

[0082] After coating, the paint film was cured for seven days at a temperature of 25 degrees Celsius and a humidity of 30%-60% according to the GB / T3324 standard "General Technical Conditions for Wooden Furniture".

[0083] Table 2 shows the test results of Examples 1-5 and Comparative Example 1.

[0084] Example Test Items Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 hardness H H H+ H+ H+ B Water resistance Level 1 Level 1 Level 1 Level 1 Level 1 Level 2 Acid resistance (10% acetic acid aqueous solution) Level 1 Level 1 Level 1 Level 1 Level 1 Level 2 Alkali resistance (10% sodium carbonate aqueous solution) Level 1 Level 1 Level 1 Level 1 Level 1 Level 3 Alcohol resistance (48% aqueous alcohol solution) Level 1 Level 1 Level 1 Level 1 Level 1 Level 3 Moist heat resistance Level 1 Level 1 Level 1 Level 1 Level 1 Level 3 Dry heat resistance Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Adhesion Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Resistance to cold and heat temperature differences qualified qualified qualified qualified qualified qualified Impact resistance Level 2 Level 2 Level 3 Level 3 Level 3 Level 2 Coating status Smooth, bubble-free, and free of shrinkage pores Smooth, bubble-free, and free of shrinkage pores Smooth, bubble-free, and free of shrinkage pores A few small bubbles, no shrinkage pores Very few small bubbles, no shrinkage pores Smooth, bubble-free, and free of shrinkage pores

[0085] (1) The test results of Examples 1-5 show that the water-based paint prepared by the present invention has excellent physical and mechanical properties and liquid resistance after coating. There are no obvious defects in the coating process, and the overall performance is excellent. The present invention uses solvent-based hydroxyl acrylic resin as the main film-forming agent of water-based paint, so that the hardness and resistance of the paint film are close to those of oil-based paint, and the performance is excellent. However, since solvent-based hydroxyl acrylic resin is difficult to disperse in the aqueous phase to form water-based paint, the present invention specifically uses castor oil polyoxyethylene ether as an emulsifier. The ester group of castor oil polyoxyethylene ether makes it well miscible with hydroxyl acrylic resin, which also contains ester group. The long hydrocarbon chain of castor oil polyoxyethylene ether is close to hydroxyl acrylic resin, and the polyoxyethylene segments of castor oil polyoxyethylene ether are all hydrophilic. Under the emulsification of castor oil polyoxyethylene ether, the hydroxyl acrylic resin is stably dispersed in the aqueous phase, which ensures the uniformity of the system. Furthermore, the hydroxyl groups contained in castor oil polyoxyethylene ether can crosslink with polyhexamethylene diisocyanate to form a film, which has little impact on the liquid resistance of the paint film, making the liquid resistance of the water-based paint close to that of the solvent-based paint.

[0086] Alkyne glycol defoamers can rapidly migrate to the gas-liquid interface of foam, spreading instantly upon the formation of a new interface, reducing dynamic tension, and thus promoting bubble migration and breakage. Mineral oil-based defoamers penetrate the foam liquid film in the form of immiscible oil droplets, physically spreading to displace foam-stabilizing components, enhancing the suppression of thick-walled and large bubbles, and achieving long-lasting foam suppression. The two defoamers have complementary mechanisms of action and synergistic interfacial behavior, with no significant antagonistic effects. In water-based hydroxy acrylic systems, they can simultaneously improve microbubbles, large bubbles, and foaming issues during application, with a comprehensive defoaming effect superior to single-component defoamers. Moreover, alkynyl glycol defoamers and mineral oil-based defoamers exhibit excellent compatibility with the system, avoiding film defects caused by defoamers.

[0087] Solvent-based hydroxyl acrylic resin, as the main film-forming agent, forms a dense three-dimensional cross-linked network structure with polyhexamethylene diisocyanate. Combined with reinforcing fillers such as glass powder and silica micropowder, this further enhances the hardness and abrasion resistance of the paint film. Anionic leveling agents further optimize the leveling properties of the paint film. When the amount of reinforcing filler in water-based paints increases, it is necessary to fine-tune the amounts of solvent-based hydroxyl acrylic resin, deionized water, and other substances to achieve a good synergistic effect.

[0088] (2) Comparative Example 2, as a water-based wood varnish made from commercially available hydroxy acrylic emulsion, further highlights the performance advantages of the water-based paint of the present invention in terms of test results: Although commercially available emulsion paint performs well in some indicators, it is far inferior to the water-based paint of Examples 1 to 5 of the present invention in terms of film hardness, alkali resistance, alcohol resistance and damp heat resistance.

[0089] (3) In addition, the inventors tried using other alkyl polyoxyethylene ethers, allyl polyoxyethylene ether ammonium, fatty alcohol polyoxyethylene ethers, isomeric alcohol polyoxyethylene ethers, hydrogenated castor oil polyoxyethylene ethers, and Tween series emulsifiers. Alkyl polyoxyethylene ether emulsifiers react too quickly with the curing agent, failing to meet the reaction rhythm required by the process and affecting the stability of the water-based paint system. Allyl polyoxyethylene ether ammonium emulsifiers lead to incomplete curing reaction, leaving unreacted components, resulting in a decrease in paint performance and failure to achieve the expected curing effect. Fatty alcohol polyoxyethylene ethers and isomeric alcohol polyoxyethylene ether emulsifiers have a generally poor emulsifying effect on this system, affecting the film quality of the water-based paint. Tween series emulsifiers: easily generate obvious bubbles during use, and the bubbles are difficult to eliminate, resulting in pores and defects on the surface after film formation.

[0090] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A water-based paint, characterized in that, The product comprises component A and component B, wherein the mass ratio of component A to component B is 100:15~25; component A comprises the following raw materials in parts by mass: 32-45 parts solvent-based hydroxyl acrylic resin, 0-0.04 parts drying agent, 1.8-2.5 parts castor oil polyoxyethylene ether, 0.5-1.5 parts defoamer, 0-40 parts reinforcing filler, 0.02-0.05 parts anionic leveling agent, 0-0.9 parts regulator, and 40-55 parts deionized water; component B comprises isocyanate compounds.

2. The water-based paint according to claim 1, characterized in that, The defoamer includes acetylenic diol defoamers and / or mineral oil-based defoamers.

3. The water-based paint according to claim 1, characterized in that, The solvent-based hydroxyl acrylic resin has a solid content of 60% to 80%, and the hydroxyl content in the solid is 2% to 5%. The solvent in the solvent-based hydroxyl acrylic resin is a lower ester.

4. The water-based paint according to claim 1, characterized in that, The regulators include pH adjusters and thickeners.

5. The water-based paint according to claim 4, characterized in that, The thickener is a polyurethane associative thickener, and the pH adjuster is 2-amino-2-methyl-1-propanol.

6. The water-based paint according to claim 1, characterized in that, The drying agent includes organotin compounds and / or organobismuth compounds.

7. The water-based paint according to claim 1, characterized in that, The reinforcing filler includes one or more of glass powder, silica micro powder, and barium sulfate, or one or two of calcium carbonate and titanium dioxide.

8. The water-based paint according to claim 1, characterized in that, Component B comprises the following raw materials in parts by weight: 70-100 parts isocyanate compound and 0-20 parts propylene glycol methyl ether acetate, wherein the isocyanate compound includes diisocyanate and / or polyisocyanate, and the NCO content of the isocyanate compound is 20%-22%.

9. A method for preparing a water-based paint as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Add solvent-based hydroxyl acrylic resin, drying agent and castor oil polyoxyethylene ether to the dispersion tank in sequence and stir at low speed until uniform; (2) Slowly add some deionized water while stirring. (3) Slowly add pH adjuster, then add defoamer, reinforcing filler, anionic leveling agent, remaining deionized water and thickener in sequence, while stirring, and finally obtain component A of water-based paint; (4) Add propylene glycol methyl ether acetate to another dispersion tank, and then slowly add the isocyanate compound to the dispersion tank while stirring. Finally, the B component of the water-based paint is obtained.

10. The method for preparing a water-based paint according to claim 9, characterized in that, The stirring speed in steps (2) and (3) is greater than that in step (1); the mass ratio of deionized water added in steps (2) and (3) is 1:1.4~2.5.