Water-based paint for surfaces of multiple materials as well as preparation method and application of water-based paint

Abstract

The invention relates to the technical field of water-based paint, in particular to water-based paint for surfaces of multiple materials and a preparation method of the water-based paint for the surfaces of the multiple materials. 4-10 parts of a coalescing agent; 0.2 to 0.5 part of a defoaming agent; 0.3 to 0.8 part of a leveling agent; 3-5 parts of a wax emulsion; 0.2 to 0.5 part of a wetting agent; 0.5 to 2 parts of a thickening agent; 2 to 4 parts of polyvinyl butyral; 1-3 parts of polyethylene glycol monomethyl ether; 0.5 to 2 parts of polyvinyl pyrrolidone; the pure acrylic emulsion is selected as a main film forming substance, carboxyl, hydroxyl and other functional groups on a molecular chain of the pure acrylic emulsion can provide abundant reaction sites, polyvinyl butyral is introduced, an aldehyde group in a molecular structure of the polyvinyl butyral can form a hydrogen bond with the surface of a base material, and meanwhile, an interpenetrating network is formed with the main emulsion through a unique chain segment structure of the polyvinyl butyral; through introduction of polyethylene glycol monomethyl ether, a flexible chain segment improves the leveling property of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of water-based coatings, and in particular to a water-based coating for multi-material surfaces and a preparation method thereof. Background Art

[0002] With the improvement of environmental awareness and the increasingly stringent environmental regulations in various countries, water-based paints are gradually replacing traditional solvent-based paints with their advantages of low VOC emissions and environmental friendliness. However, existing water-based paints still have many technical difficulties in terms of multi-material applicability, comprehensive performance and long-term protection.

[0003] In the prior art, common water-based coatings mainly use a single emulsion system, such as acrylic emulsion, styrene acrylic emulsion, etc. Although such systems have certain film-forming properties, due to the single molecular structure and the lack of an effective cross-linking network, the key properties of the coating, such as mechanical strength, weather resistance and adhesion, are difficult to meet the actual application requirements. In particular, on the surfaces of different substrates, due to the differences in the interface bonding mechanism, problems such as insufficient adhesion, easy cracking, and poor weather resistance often occur.

[0004] Furthermore, some technical solutions improve the performance of coatings by adding crosslinking agents, but excessive crosslinking often makes the coating too rigid and loses the necessary toughness and ductility. Another solution uses silicone modification to improve the weather resistance of the coating, but the cost is high and compatibility issues are prone to occur. In addition, the additive system in the existing formula is often relatively simple, lacks systematic collaborative design, and cannot achieve synergistic enhancement of multiple functions.

[0005] The inventors of the present invention have conducted in-depth research and found that the improvement of coating performance cannot rely solely on the modification of a single component, but requires the construction of a multiple synergistic network structure at the molecular level. By carefully designing the formula composition and cleverly utilizing the physical and chemical interactions between the components, a new water-based coating system with excellent comprehensive performance can be constructed. Summary of the invention

[0006] The invention provides a water-based coating for multi-material surfaces and a preparation method thereof, so as to solve the deficiencies of the prior art.

[0007] The water-based coating for multi-material surface of the present invention comprises the following components in parts by mass:

[0008] Acrylic emulsion 60-80 parts;

[0009] 4-10 parts of film-forming aid;

[0010] Defoaming agent 0.2-0.5 parts;

[0011] Leveling agent 0.3-0.8 parts;

[0012] 3-5 parts wax emulsion;

[0013] Wetting agent 0.2-0.5 parts;

[0014] Thickener 0.5-2 parts;

[0015] 2-4 parts of polyvinyl butyral;

[0016] 1-3 parts of polyethylene glycol monomethyl ether;

[0017] Polyvinyl pyrrolidone 0.5-2 parts;

[0018] Add water to 100 parts.

[0019] Specifically, the acrylic emulsion is a pure acrylic emulsion with a solid content of 45-50wt%, a pH value of 8-9, and a viscosity of 200S-400S; the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate with a solid content of 30-35wt%, a pH value of 7-8, and a viscosity of 20-30mPa·s; the defoamer is a polyether-modified polysiloxane defoamer with a solid content of 20-40wt%; the leveling agent is an acrylic leveling agent with a solid content of 50-55wt%, pH value of 7-8, and a viscosity of 20-30mPa·s. The H value is 8-9, and the viscosity is 50-80mPa·s; the wax emulsion is a natural plant wax emulsion, the wax solid content is 28-33wt%, the pH value is 7-8, and the viscosity is 600-700mPa·s; the wetting agent is a polyether-modified organic silicone wetting agent, the solid content is 10-15wt%, the pH value is 8-9, and the viscosity is 20-30mPa·s; the thickener is a polyurethane thickener, the solid content is 20-27wt%, the pH value is 5-7, and the viscosity is 20-40Pa·s.

[0020] Specifically, the solid content of the polyvinyl butyral is 40-45wt%, and the pH value is 6-7; the molecular weight of the polyethylene glycol monomethyl ether is 2000-4000, and the purity is not less than 98%; the K value of the polyvinyl pyrrolidone is 30-35, and the pH value is 5-7.

[0021] The preparation method of the water-based coating comprises the following steps:

[0022] (1) taking the raw materials of each component according to the weight ratio for use;

[0023] (2) Add solvent water into the main tank, add thickener while stirring, and after uniform dispersion, heat to 30-35° C. while stirring, and then maintain a constant temperature until the thickener is completely swollen to obtain a thickener aqueous solution;

[0024] (3) Install a vacuum device on the vacuum degassing tank, connect the main tank and the vacuum degassing tank through a pipeline, and turn on the vacuum pump;

[0025] (4) Add the acrylic emulsion into the main tank, start the low-speed mixer, and then add the thickener aqueous solution into the main tank and disperse evenly;

[0026] (5) starting a high-speed stirrer, adding a film-forming aid, a defoaming agent, a leveling agent, a wax emulsion, a wetting agent, polyvinyl butyral, polyethylene glycol monomethyl ether and polyvinyl pyrrolidone in sequence, and mixing them evenly;

[0027] (6) Stop the air compressor and turn off the vacuum pump, grind and disperse the materials in the main tank, filter them, and cool them to room temperature.

[0028] Specifically, in step (2), the stirring speed is 800-1000 rpm and the stirring time is 20-30 min.

[0029] Specifically, in step (4), the rotation speed of the low-speed stirrer is 300-500 rpm.

[0030] Specifically, in step (5), the rotation speed of the high-speed stirrer is 1200-1500 rpm, and the stirring time is 40-50 min.

[0031] Specifically, in step (3), the vacuum degree is -0.05 to -0.08 MPa.

[0032] Specifically, in step (6), a 100-mesh sieve is used for filtration, and the filtrate is allowed to stand for 2-4 hours after filtration.

[0033] The water-based paint is used for surface coating of one or more materials selected from metal, plastic, wood, leather, stone and composite materials.

[0034] The technical solution of the present invention achieves the above-mentioned objectives through the following innovative designs: First, pure acrylic emulsion is selected as the main film-forming substance, and functional groups such as carboxyl and hydroxyl groups on its molecular chain can provide abundant reaction sites. Secondly, polyvinyl butyral is introduced, and the aldehyde group in its molecular structure can form hydrogen bonds with the surface of the substrate, and at the same time, an interpenetrating network is formed with the main emulsion through its unique segment structure. Thirdly, through the introduction of polyethylene glycol monomethyl ether, its flexible segment not only improves the leveling property of the system, but also provides a dynamic and reversible hydrogen bonding effect at the molecular level, giving the coating a certain self-healing ability.

[0035] In particular, the present invention has made innovative breakthroughs in the design of the additive system. By adding polyvinyl pyrrolidone, the pyrrolidone ring in its molecule forms multiple hydrogen bonds with other components, which significantly improves the stability of the system and the water resistance of the coating. At the same time, the dosage of various functional additives is precisely controlled to ensure the maximization of the synergistic effect between them.

[0036] Beneficial effects of the present invention:

[0037] 1. Excellent multi-substrate applicability is achieved, and the coating shows excellent adhesion on different substrates such as metal, plastic, and wood (cross-cut test level 1);

[0038] 2. Through multiple synergistic molecular network designs, the coating exhibits excellent mechanical properties, with an impact strength of 48cm while maintaining good toughness;

[0039] 3. Excellent weather resistance and water resistance. After 1000h of xenon lamp accelerated aging, the performance retention rate reaches more than 90%, far exceeding the existing technical level;

[0040] 4. An unexpected self-healing effect was discovered, which provides a new technical path for long-term protection of coatings;

[0041] 5. The production process is simple and controllable, the cost is moderate, and it has good prospects for industrial application.

[0042] In summary, the present invention has successfully solved many technical problems in the field of water-based coatings through innovative molecular design and process optimization, achieved excellent comprehensive performance, and has important theoretical and practical value. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The core innovation of the water-based coating for multi-material surface of the present invention lies in its unique formula combination: acrylic emulsion (60-80 parts) is used as the main film-forming substance, and styrene acrylic emulsion or pure acrylic emulsion is selected, which has excellent weather resistance and adhesion, solid content of 45-50wt%, ensuring good film-forming performance, weak alkaline environment with pH value of 8-9 is conducive to system stability, and the viscosity range of 200S-400S ensures the construction performance of the coating. The film-forming aid (4-10 parts) is selected from 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, the ester group in its molecular structure provides a good plasticizing effect, the solid content is 30-35wt%, balancing the film-forming performance and VOC content, and the low viscosity of 20-30mPa·s is conducive to uniform dispersion. The defoamer (0.2-0.5 parts) adopts a polyether-modified polysiloxane structure, which is cleverly designed. The polyether segment provides compatibility with the water phase, and the siloxane skeleton gives an excellent defoaming effect. The solid content of 20-40wt% ensures the economical use. The leveling agent (0.3-0.8 parts) uses water-based polyacrylate, a high solid content of 50-55wt%, a pH value of 8-9 to match the system, and a viscosity of 50-80mPa·s to ensure a good leveling effect. The wax emulsion (3-5 parts) adopts nano-grade natural plant wax, 28-33wt% wax solid content, and a viscosity range of 600-700mPa·s, providing wear resistance and hand feel. The wetting agent (0.2-0.5 parts) adopts a polyether-modified organic siloxane structure, a low solid content of 10-15wt%, excellent interfacial activity, and improves the wettability of the substrate. Thickener (0.5-2 parts) uses ASE-60 associative polyurethane, 20-27wt% solid content, moderate pH value 5-7, high viscosity (20-40Pa·s) to provide good thickening effect. Polyvinyl butyral (2-4 parts) provides excellent substrate adhesion, forms an interpenetrating network structure with acrylic emulsion, enhances the toughness and impact resistance of the coating, solid content 40-45wt%, pH value 6-7; Polyethylene glycol monomethyl ether (1-3 parts) improves the leveling performance of the coating, improves the compatibility of the film-forming material, and enhances the flexibility of the coating, molecular weight 2000-4000, purity ≥98%; Polyvinyl pyrrolidone (0.5-2 parts) improves system stability, improves wetting and dispersion effects, and enhances the water resistance of the coating, K value 30-35, pH value 5-7. The aldehyde group of PVB forms hydrogen bonds with the substrate, and PVP provides additional polar groups, and the multiple components work together to improve adhesion; PEG acts as a plasticizer to improve film formation, and PVB provides network crosslinking points to form a uniform and dense coating; PVB provides mechanical strength, PEG provides flexibility, and PVP provides stability. UV resistance is improved by 30%, salt spray resistance is improved by 40%, and anti-aging performance is significantly improved; impact strength is increased by 50%, adhesion is increased by 35%, and flexibility is significantly improved; leveling is improved, stability is enhanced, and applicability is expanded.

[0045] The innovation of the preparation process is reflected in the thickener pre-swelling step, which controls the temperature at 30-35°C to ensure sufficient swelling and improve the stability of the system; the vacuum degassing process reduces bubble defects, improves film quality, and improves appearance performance; the step-by-step addition sequence, adds the main components under low-speed stirring conditions, and supplements functional additives under high-speed stirring to ensure uniform dispersion.

[0046] The coating exhibits excellent comprehensive performance: weather resistance includes light resistance, water resistance, alkali resistance, acid resistance, salt resistance up to level 7-8, aging resistance up to level 6-7, and salt spray resistance up to level 9-10; mechanical properties include wear resistance 2-3, hardness up to 2-3H, and flexibility 4-5; optical properties include transparency ≥60%, gloss 93-98 degrees, and yellowing resistance 2-3; adhesion includes cross-cutting test up to level 1, applicable to a variety of substrates, and strong interface bonding. Technical innovations include multi-component synergistic effect, precise ratio of each component, complementary functions, and synergistic performance improvement; process innovation, precise temperature control, vacuum degassing, and step-by-step feeding; broad-spectrum applicability, applicable to a variety of substrates, a variety of coating effects, and flexible construction methods. The coating has significant industrial application value: environmentally friendly water-based system, excellent performance indicators, a wide range of applications, and simple and feasible processes. This invention has achieved excellent comprehensive performance through carefully designed formula composition and process, and has important practical value and innovative significance.

[0047] Example 1: A water-based coating for multi-material surfaces and a preparation method thereof

[0048] The water-based coating of this embodiment comprises the following components by mass: 60 parts of pure acrylic emulsion, 4 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 0.2 parts of polyether-modified polysiloxane defoamer, 0.3 parts of acrylic leveling agent, 3 parts of natural plant wax emulsion, 0.2 parts of polyether-modified organosiloxane wetting agent, 0.5 parts of polyurethane thickener, 2 parts of polyvinyl butyral, 1 part of polyethylene glycol monomethyl ether, 0.5 parts of polyvinyl pyrrolidone, and water is added to 100 parts.

[0049] Among them, the solid content of the pure acrylic emulsion used is 45wt%, the pH value is 8, and the viscosity is 200S; the solid content of the film-forming aid is 30wt%, the pH value is 7, and the viscosity is 20mPa·s; the solid content of the defoamer is 20wt%; the solid content of the leveling agent is 50wt%, the pH value is 8, and the viscosity is 50mPa·s; the solid content of the wax emulsion is 28wt%, the pH value is 7, and the viscosity is 600mPa·s; the solid content of the wetting agent is 10wt%, the pH value is 8, and the viscosity is 20mPa·s; the solid content of the thickener is 20wt%, the pH value is 5, and the viscosity is 20Pa·s; the solid content of polyvinyl butyral is 40wt%, and the pH value is 6; the molecular weight of polyethylene glycol monomethyl ether is 2000, and the purity is 98%; the K value of polyvinyl pyrrolidone is 30, and the pH value is 5.

[0050] The preparation method comprises the following steps:

[0051] First, weigh each component accurately according to the above proportions;

[0052] Secondly, add water to the main tank, add thickener at a stirring speed of 800 rpm, stir for 20 minutes until it is evenly dispersed, and at the same time raise the temperature to 30°C and maintain a constant temperature until the thickener is fully swollen;

[0053] Then, install a vacuum device on the vacuum degassing tank, set the vacuum degree to -0.05MPa, connect the main tank with the degassing tank, and start the vacuum pump;

[0054] Next, add pure acrylic emulsion into the main tank, stir at 300 rpm, and add the swollen thickener aqueous solution, stirring until uniform;

[0055] Then adjust the stirring speed to 1200 rpm, add film-forming aid, defoamer, leveling agent, wax emulsion, wetting agent, polyvinyl butyral, polyethylene glycol monomethyl ether and polyvinyl pyrrolidone in sequence, and stir for 40 minutes until the mixture is evenly mixed;

[0056] Finally, stop the vacuum pump, filter the material through a 100-mesh sieve, and let it stand for 2 hours to obtain the finished product.

[0057] Example 2: A water-based coating for multi-material surfaces and a preparation method thereof

[0058] The water-based coating of this embodiment comprises the following components by mass: 70 parts of pure acrylic emulsion, 7 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 0.35 parts of polyether-modified polysiloxane defoamer, 0.5 parts of acrylic leveling agent, 4 parts of natural plant wax emulsion, 0.35 parts of polyether-modified organosiloxane wetting agent, 1.2 parts of polyurethane thickener, 3 parts of polyvinyl butyral, 2 parts of polyethylene glycol monomethyl ether, 1.2 parts of polyvinyl pyrrolidone, and water is added to 100 parts.

[0059] Among them, the solid content of the pure acrylic emulsion used is 47.5wt%, the pH value is 8.5, and the viscosity is 300S; the solid content of the film-forming aid is 32.5wt%, the pH value is 7.5, and the viscosity is 25mPa·s; the solid content of the defoamer is 30wt%; the solid content of the leveling agent is 52.5wt%, the pH value is 8.5, and the viscosity is 65mPa·s; the solid content of the wax emulsion is 30.5wt%, the pH value is 7.5, and the viscosity is 650mPa·s; the solid content of the wetting agent is 12.5wt%, the pH value is 8.5, and the viscosity is 25mPa·s; the solid content of the thickener is 23.5wt%, the pH value is 6, and the viscosity is 30Pa·s; the solid content of polyvinyl butyral is 42.5wt%, and the pH value is 6.5; the molecular weight of polyethylene glycol monomethyl ether is 3000, and the purity is 98.5%; the K value of polyvinyl pyrrolidone is 32.5, and the pH value is 6.

[0060] The preparation method comprises the following steps:

[0061] First, weigh each component accurately according to the above proportions;

[0062] Secondly, add water to the main tank, add thickener at a stirring speed of 900 rpm, stir for 25 minutes until it is evenly dispersed, and at the same time raise the temperature to 32.5°C and maintain a constant temperature until the thickener is fully swollen;

[0063] Then, install a vacuum device on the vacuum degassing tank, set the vacuum degree to -0.065MPa, connect the main tank with the degassing tank, and start the vacuum pump;

[0064] Next, add pure acrylic emulsion into the main tank, stir at 400 rpm, and add the swollen thickener aqueous solution, stirring until uniform;

[0065] Then adjust the stirring speed to 1350 rpm, add film-forming aid, defoamer, leveling agent, wax emulsion, wetting agent, polyvinyl butyral, polyethylene glycol monomethyl ether and polyvinyl pyrrolidone in sequence, and stir for 45 minutes until the mixture is evenly mixed;

[0066] Finally, stop the vacuum pump, filter the material through a 100-mesh sieve, and let it stand for 3 hours to obtain the finished product.

[0067] Example 3: A water-based coating for multi-material surfaces and a preparation method thereof

[0068] The water-based coating of this embodiment comprises the following components by mass: 80 parts of pure acrylic emulsion, 10 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 0.5 parts of polyether-modified polysiloxane defoamer, 0.8 parts of acrylic leveling agent, 5 parts of natural plant wax emulsion, 0.5 parts of polyether-modified organosiloxane wetting agent, 2 parts of polyurethane thickener, 4 parts of polyvinyl butyral, 3 parts of polyethylene glycol monomethyl ether, 2 parts of polyvinyl pyrrolidone, and water is added to 100 parts.

[0069] Among them, the solid content of the pure acrylic emulsion used is 50wt%, the pH value is 9, and the viscosity is 400S; the solid content of the film-forming aid is 35wt%, the pH value is 8, and the viscosity is 30mPa·s; the solid content of the defoamer is 40wt%; the solid content of the leveling agent is 55wt%, the pH value is 9, and the viscosity is 80mPa·s; the solid content of the wax emulsion is 33wt%, the pH value is 8, and the viscosity is 700mPa·s; the solid content of the wetting agent is 15wt%, the pH value is 9, and the viscosity is 30mPa·s; the solid content of the thickener is 27wt%, the pH value is 7, and the viscosity is 40Pa·s; the solid content of polyvinyl butyral is 45wt%, and the pH value is 7; the molecular weight of polyethylene glycol monomethyl ether is 4000, and the purity is 99%; the K value of polyvinyl pyrrolidone is 35, and the pH value is 7.

[0070] The preparation method comprises the following steps:

[0071] First, weigh each component accurately according to the above proportions;

[0072] Secondly, add water to the main tank, add thickener at a stirring speed of 1000 rpm, stir for 30 minutes until it is evenly dispersed, and at the same time raise the temperature to 35°C and maintain a constant temperature until the thickener is fully swollen;

[0073] Then, install a vacuum device on the vacuum degassing tank, set the vacuum degree to -0.08MPa, connect the main tank with the degassing tank, and start the vacuum pump;

[0074] Next, add pure acrylic emulsion into the main tank, stir at 500 rpm, and add the swollen thickener aqueous solution, stirring until uniform;

[0075] Then adjust the stirring speed to 1500 rpm, add film-forming aid, defoamer, leveling agent, wax emulsion, wetting agent, polyvinyl butyral, polyethylene glycol monomethyl ether and polyvinyl pyrrolidone in sequence, and stir for 50 minutes until the mixture is evenly mixed;

[0076] Finally, stop the vacuum pump, filter the material through a 100-mesh sieve, and let it stand for 4 hours to obtain the finished product.

[0077] Example 4: A water-based coating for multi-material surfaces and a preparation method thereof

[0078] The water-based coating of this embodiment comprises the following components by mass: 75 parts of pure acrylic emulsion, 8 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 0.4 parts of polyether-modified polysiloxane defoamer, 0.6 parts of acrylic leveling agent, 4.5 parts of natural plant wax emulsion, 0.4 parts of polyether-modified organosiloxane wetting agent, 1.5 parts of polyurethane thickener, 3.5 parts of polyvinyl butyral, 2.5 parts of polyethylene glycol monomethyl ether, 1.5 parts of polyvinyl pyrrolidone, and water is added to 100 parts.

[0079] Among them, the solid content of the pure acrylic emulsion used is 48wt%, the pH value is 8.8, and the viscosity is 350S; the solid content of the film-forming aid is 33wt%, the pH value is 7.8, and the viscosity is 28mPa·s; the solid content of the defoamer is 35wt%; the solid content of the leveling agent is 53wt%, the pH value is 8.8, and the viscosity is 70mPa·s; the solid content of the wax emulsion is 31wt%, the pH value is 7.8, and the viscosity is 650mPa·s; the solid content of the wetting agent is 13wt%, the pH value is 8.8, and the viscosity is 28mPa·s; the solid content of the thickener is 25wt%, the pH value is 6.5, and the viscosity is 35Pa·s; the solid content of polyvinyl butyral is 43wt%, and the pH value is 6.8; the molecular weight of polyethylene glycol monomethyl ether is 3500, and the purity is 98.8%; the K value of polyvinyl pyrrolidone is 33, and the pH value is 6.5.

[0080] The preparation method comprises the following steps:

[0081] First, weigh each component accurately according to the above proportions;

[0082] Secondly, add water to the main tank, add thickener at a stirring speed of 950 rpm, stir for 28 minutes until it is evenly dispersed, and at the same time raise the temperature to 33°C and maintain a constant temperature until the thickener is fully swollen;

[0083] Then, install a vacuum device on the vacuum degassing tank, set the vacuum degree to -0.07MPa, connect the main tank with the degassing tank, and start the vacuum pump;

[0084] Next, add pure acrylic emulsion into the main tank, stir at 450 rpm, and add the swollen thickener aqueous solution, stirring until uniform;

[0085] Then adjust the stirring speed to 1400 rpm, add film-forming aid, defoamer, leveling agent, wax emulsion, wetting agent, polyvinyl butyral, polyethylene glycol monomethyl ether and polyvinyl pyrrolidone in sequence, and stir for 48 minutes until the mixture is evenly mixed;

[0086] Finally, stop the vacuum pump, filter the material through a 100-mesh sieve, and let it stand for 3.5 hours to obtain the finished product.

[0087] Preferably, the components in this embodiment form a good synergistic effect through precise proportioning and strictly controlled preparation process. Among them, pure acrylic emulsion, as the main film-forming substance, forms an interpenetrating network structure with polyvinyl butyral, which significantly improves the mechanical strength of the coating; the alcohol ether structure of the film-forming aid effectively improves the film-forming performance; the addition of polyethylene glycol monomethyl ether optimizes the leveling performance and provides a moderate plasticizing effect; polyvinyl pyrrolidone improves the system stability and water resistance of the coating through its unique molecular structure.

[0088] Each example embodies the synergistic effect between components and the precise control of process parameters, ensuring the best performance of the coating. The experimental results show that the water-based coating prepared by the above formula and process has excellent adhesion, weather resistance, mechanical strength and construction performance, and can be widely used in surface coating of various substrates.

[0089] Comparative Example 1: A water-based coating for multi-material surfaces and a preparation method thereof

[0090] (Corresponding to Example 1, verifying the synergistic effect of polyvinyl butyral)

[0091] The composition of this comparative example is substantially the same as that of Example 1, except that no polyvinyl butyral is added, and other components and process parameters remain unchanged. The preparation method is the same as that of Example 1, but the step of adding polyvinyl butyral is skipped.

[0092] Preferably, by comparison with Example 1, it is found that the adhesion of the coating is significantly reduced by 45% and the impact strength is reduced by 38% after the absence of polyvinyl butyral. This is because polyvinyl butyral can form an interpenetrating network structure with the acrylic emulsion, and its aldehyde group forms a hydrogen bond with the substrate, thereby providing additional interface bonding force. This result verifies the important synergistic effect of polyvinyl butyral in the present invention.

[0093] Comparative Example 2: A water-based coating for multi-material surfaces and a preparation method thereof

[0094] (Corresponding to Example 2, verifying the effect of polyethylene glycol monomethyl ether)

[0095] In this comparative example, the amount of polyethylene glycol monomethyl ether is increased from 2 parts to 5 parts, which is beyond the scope of the present invention. Other components and process parameters are the same as those in Example 2.

[0096] Further, the experimental results show that excessive polyethylene glycol monomethyl ether causes the water resistance of the coating to decrease by 35% and the surface hardness to decrease by 28%. This shows that the amount of polyethylene glycol monomethyl ether needs to be strictly controlled within the scope of the present invention to achieve the best synergistic effect with other components. Excessive addition will destroy the cross-linked network structure of the coating and affect the overall performance.

[0097] Comparative Example 3: A water-based coating for multi-material surfaces and a preparation method thereof

[0098] (Corresponding to Example 3, verifying the importance of process parameters)

[0099] This comparative example adopts the formulation of Example 3, but the stirring speed is uniformly reduced to 500 rpm, the stirring time is shortened to 15 min, and other process parameters remain unchanged.

[0100] Preferably, the test results show that improper process parameters lead to uneven dispersion of components, obvious stratification of the coating, a 42% decrease in adhesion, and a 33% decrease in weather resistance. This verifies the scientific nature and necessity of the process parameters of the present invention, and that appropriate stirring speed and time are the key to ensuring full interaction of the components.

[0101] Comparative Example 4: A water-based coating for multi-material surfaces and a preparation method thereof

[0102] (Corresponding to Example 4, verifying the effect of polyvinyl pyrrolidone)

[0103] In this comparative example, no polyvinyl pyrrolidone is added, and other components and process parameters are consistent with those in Example 4.

[0104] Furthermore, the experiment found that without polyvinyl pyrrolidone, the storage stability of the coating was significantly reduced, and obvious stratification occurred after 3 months; at the same time, the water resistance of the coating was reduced by 40%. This fully demonstrates that polyvinyl pyrrolidone, through its unique molecular structure, plays an irreplaceable synergistic role in providing system stability and improving the water resistance of the coating.

[0105] Comparative Example 5: A water-based coating for multi-material surfaces and a preparation method thereof

[0106] (Corresponding to Example 1, verifying the importance of group allocation ratio)

[0107] In this comparative example, the amount of acrylic emulsion is reduced to 40 parts, while the amount of film-forming aid is increased to 15 parts. Other components and process parameters are the same as those in Example 1.

[0108] Preferably, the test results show that after changing the key component ratio, the film-forming performance of the coating is significantly deteriorated, cracking occurs, and the adhesion is reduced by 55%. This verifies the scientific nature of the ratio of each component in the formula of the present invention. Only within the appropriate ratio range can the best synergistic effect be achieved.

[0109] Comparative Example 6: A water-based coating for multi-material surfaces and a preparation method thereof

[0110] (Corresponding to Example 2, verifying the necessity of vacuum degassing process)

[0111] This comparative example adopts the formulation of Example 2, but omits the vacuum degassing process and directly performs stirring and mixing at normal pressure.

[0112] Furthermore, the experimental results show that there are a large number of bubble defects in the coating, which affects the appearance quality and reduces the mechanical properties by 38%, which proves the importance of the vacuum degassing process in the present invention for obtaining high-quality coatings.

[0113] Through the systematic study of the above six comparative examples, the innovation and scientificity of the present invention in terms of formula composition, component ratio and process parameters are fully verified. Experimental data show that only under the conditions specified in the present invention can the components exert the best synergistic effect and obtain a water-based coating product with excellent performance. These results provide sufficient experimental support for the creativity of the present invention.

[0114] Based on the technical features and innovations of the present invention, the following system performance test scheme is designed:

[0115] Test item 1: coating comprehensive performance test

[0116] Test conditions and methods:

[0117] All samples were prepared and tested under a standard environment with a temperature of 23±2℃ and a relative humidity of 50±5%. The coating was sprayed on aluminum plates, stainless steel plates, PVC plates and wooden plates, and the dry film thickness was controlled at 40±2μm. The tests were carried out according to the following standards:

[0118] Preferably, the weather resistance test is performed using a xenon lamp aging tester according to GB / T1879-2000 standard, and the test conditions are: irradiance 0.55W / m 2 nm, blackboard temperature 65±3℃, relative humidity 50±5%, spraying 18min / cycle, interval 102min, total test time 1000h.

[0119] Furthermore, the adhesion test was conducted by the cross-cut method according to GB / T9286-1998 standard, using a QFH-A paint film adhesion tester, with a cross-cut spacing of 2 mm, and the average value was taken from 5 test points.

[0120] In addition, the water resistance test was carried out according to GB / T1733-1993 standard, and the coating was rated after being immersed in deionized water at 23±2℃ for 168h.

[0121] Mechanical performance tests include:

[0122] 1. Impact resistance: GB / T1732-1993, using QCJ drop ball impact tester, weight 1kg, maximum drop distance 50cm;

[0123] 2. Wear resistance: GB / T1768-2008, using CS-10 grinding wheel, load 500g, test 500 revolutions;

[0124] 3. Pencil hardness: GB / T6739-2006.

[0125] The test results of the embodiments and comparative examples of the present invention are shown in the following table:

[0126] The test results of the basic properties of the coating are shown in Table 1:

[0127]

[0128]

[0129] Table 1

[0130] Test Item 2: Coating Structure Characterization

[0131] The cross-sectional morphology of the coating was observed by scanning electron microscopy (SEM), using Thermo Fisher Helios G4 CX, accelerating voltage 5 kV. The molecular structure was analyzed by Fourier transform infrared spectroscopy (FTIR), using Bruker VERTEX 70, resolution 4 cm-1, scanning times 32 times.

[0132] Preferably, the SEM results of Example 2 show that the coating presents a uniform and dense network structure, and no obvious phase separation phenomenon is observed. However, in Comparative Example 1, due to the lack of polyvinyl butyral, obvious discontinuous areas and microcracks appear.

[0133] Furthermore, FTIR analysis confirmed the expected chemical bonding between the components. In Example 2, a strong ester characteristic peak appeared at 1735 cm-1, and obvious hydrogen bonding was observed in the 3300-3500 cm-1 region.

[0134] The coating storage stability test results are shown in Table 2:

[0135] Sample No. 3-month stability 6-month stability Example 1 No stratification and settlement Slightly delaminated Example 2 No stratification and settlement No stratification and settlement Example 3 No stratification and settlement No stratification and settlement Example 4 No stratification and settlement Slight delamination Comparative Example 1 Slightly delaminated Obvious stratification Comparative Example 2 Obvious stratification Severe stratification Comparative Example 3 Slight delamination Obvious stratification Comparative Example 4 Obvious stratification Severe stratification Comparative Example 5 Obvious stratification Severe stratification Comparative Example 6 Slightly delaminated Obvious stratification

[0136] Table 2

[0137] Based on the above test results, the present invention has the following unexpected technical effects:

[0138] 1. Excellent interface bonding mechanism: The interpenetrating network structure formed by polyvinyl butyral and acrylic emulsion in the present invention not only provides physical crosslinking points, but its aldehyde groups can also form chemical bonds with the substrate surface, which explains the excellent adhesion (level 1) of Examples 1-4. This multiple bonding mechanism is unforeseeable in the prior art.

[0139] 2. Special self-healing effect: The introduction of polyethylene glycol monomethyl ether not only provides leveling properties, but its flexible chain segments also give the coating a certain self-healing ability. When the coating is slightly damaged, the molecular chains can rearrange themselves through thermal motion to repair microscopic defects. This discovery provides new ideas for the long-term protection of the coating.

[0140] 3. Synergistic effect: A complex physical and chemical network structure is formed between the components, which not only provides excellent mechanical properties, but also gives the coating good weather resistance and water resistance. This multiple synergistic effect cannot be achieved by a single component or simple combination.

[0141] In summary, Example 2 exhibits the best comprehensive performance and can be used as the best implementation scheme of the present invention. The test results fully demonstrate the innovation of the present invention in formulation design and process control, achieve the expected technical effects, and discover some unexpected excellent performances.

[0142] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A water-based coating for a multi-material surface, characterized in that: In parts by mass, it includes the following components: Acrylic emulsion 60-80 parts; 4-10 parts of film-forming aid; Defoaming agent 0.2-0.5 parts; Leveling agent 0.3-0.8 parts; 3-5 parts wax emulsion; Wetting agent 0.2-0.5 parts; Thickener 0.5-2 parts; 2-4 parts of polyvinyl butyral; 1-3 parts of polyethylene glycol monomethyl ether; Polyvinyl pyrrolidone 0.5-2 parts; Add water to 100 parts.

2. The water-based paint according to claim 1, characterized in that: The acrylic emulsion is a pure acrylic emulsion with a solid content of 45-50wt%, a pH value of 8-9, and a viscosity of 200S-400S; the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate with a solid content of 30-35wt%, a pH value of 7-8, and a viscosity of 20-30mPa·s; the defoamer is a polyether-modified polysiloxane defoamer with a solid content of 20-40wt%; the leveling agent is an acrylic leveling agent with a solid content of 50-55wt%, a pH value of 8-9, and a viscosity of 50-80 mPa·s; the wax emulsion is a natural plant wax emulsion, with a wax solid content of 28-33wt%, a pH value of 7-8, and a viscosity of 600-700 mPa·s; the wetting agent is a polyether-modified organic siloxane wetting agent, with a solid content of 10-15wt%, a pH value of 8-9, and a viscosity of 20-30 mPa·s; the thickener is a polyurethane thickener, with a solid content of 20-27wt%, a pH value of 5-7, and a viscosity of 20-40 Pa·s.

3. The water-based paint according to claim 2, characterized in that: The solid content of the polyvinyl butyral is 40-45wt%, and the pH value is 6-7; the molecular weight of the polyethylene glycol monomethyl ether is 2000-4000, and the purity is not less than 98%; the K value of the polyvinyl pyrrolidone is 30-35, and the pH value is 5-7.

4. The method for preparing a water-based coating according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) taking the raw materials of each component according to the weight ratio for use; (2) Add solvent water into the main tank, add thickener while stirring, and after uniform dispersion, heat to 30-35° C. while stirring, and then maintain a constant temperature until the thickener is completely swollen to obtain a thickener aqueous solution; (3) Install a vacuum device on the vacuum degassing tank, connect the main tank and the vacuum degassing tank through a pipeline, and turn on the vacuum pump; (4) Add the acrylic emulsion into the main tank, start the low-speed mixer, and then add the thickener aqueous solution into the main tank and disperse evenly; (5) starting a high-speed stirrer, adding a film-forming aid, a defoaming agent, a leveling agent, a wax emulsion, a wetting agent, polyvinyl butyral, polyethylene glycol monomethyl ether and polyvinyl pyrrolidone in sequence, and mixing them evenly; (6) Stop the air compressor and turn off the vacuum pump, grind and disperse the materials in the main tank, filter them, and cool them to room temperature.

5. The preparation method according to claim 4, characterized in that: In the step (2), the stirring speed is 800-1000 rpm and the stirring time is 20-30 min.

6. The preparation method according to claim 4, characterized in that: In the step (4), the rotation speed of the low-speed stirrer is 300-500 rpm.

7. The preparation method according to claim 4, characterized in that: In the step (5), the rotation speed of the high-speed stirrer is 1200-1500 rpm, and the stirring time is 40-50 min.

8. The preparation method according to claim 4, characterized in that: In the step (3), the vacuum degree is -0.05 to -0.08 MPa.

9. The preparation method according to claim 4, characterized in that: In the step (6), a 100-mesh screen is used for filtration, and the product is allowed to stand for 2-4 hours after filtration.

10. The use of the water-based paint according to any one of claims 1 to 3, characterized in that: The water-based paint is used for surface coating of one or more materials selected from metal, plastic, wood, leather, stone and composite materials.

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