High-gloss high-water-resistance waterborne acrylic polyurethane finish paint and preparation method thereof

Abstract

The invention discloses a high-gloss high-water-resistance waterborne acrylic polyurethane finish paint and a preparation method thereof, and belongs to the field of protective decorative coatings. The water-based acrylic polyurethane finish paint comprises a hydroxyl acrylic dispersion, an amine neutralizer, a coalescing agent, a graphene dispersion liquid, a dispersing agent, carbon black, precipitated barium sulphate, sericite, a defoaming agent, a flatting agent, a base material wetting agent, a rheological agent, deionized water, an isocyanate curing agent, propylene glycol diacetate and an organic silicon coupling agent. The water-based acrylic polyurethane finish paint prepared by the invention has high gloss, excellent water resistance, impact resistance, hardness and artificial aging resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of protective decorative coatings, and in particular relates to a high-gloss and high-water-resistant water-based acrylic polyurethane topcoat and a preparation method thereof. Background Art

[0002] Railway passenger cars, buses, and sanitation vehicles are often parked for a long time in a high temperature and high humidity environment during use. In particular, sanitation vehicles may have water-containing substances in the carriage for a long time, which can easily cause the paint film of the box to bubble and bulge easily during use, and the box substrate is corroded, thereby shortening the service life of the vehicle. This requires the paint used to have high water resistance. Existing water-based topcoats have good resistance to artificial aging and decorative properties, but due to the presence of more hydrophilic groups in the dispersant, curing agent and dispersion in the formula, the water resistance of the paint film is generally poor, and there is little exploration in the prior art on how to improve the water resistance of the topcoat. The present invention has good water resistance, high hardness, good toughness, and good weather resistance. It is an invention that can protect the surface coating of the coated object from being destroyed in a high temperature and high humidity environment, prevent the base material from being corroded, and can also give the surface of the coated object a good gloss and paint film appearance.

[0003] Existing protective decorative coatings mainly include water-based acrylic topcoat, water-based alkyd topcoat, water-based fluorocarbon topcoat, water-based amino acrylic topcoat, and water-based acrylic polyurethane topcoat. These coatings cannot meet the requirements of resistance to water at 40°C for more than 30 days under high gloss conditions. Therefore, the development of a high-gloss, highly water-resistant water-based acrylic polyurethane topcoat is an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of poor water resistance of water-based acrylic polyurethane topcoat, and to provide a high-gloss and high-water-resistant water-based acrylic polyurethane topcoat and a preparation method thereof. The water-based acrylic polyurethane topcoat prepared by the present invention has high gloss, excellent water resistance, impact resistance, excellent hardness and resistance to artificial aging.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: The present invention provides a high-gloss and high-water-resistant water-based acrylic polyurethane topcoat, comprising a component A and a component B, wherein the mass ratio of the component A to the component B is 100:(20-30); The component A comprises: 45-65 parts of hydroxy acrylic acid dispersion, 0.2-0.5 parts of amine neutralizer, 5-8 parts of film-forming aid, 3-6 parts of graphene dispersion, 3-6 parts of dispersant, 1-3 parts of carbon black, 5-12 parts of precipitated barium sulfate, 2-5 parts of sericite, 0.3-0.6 parts of defoamer, 0.1-0.4 parts of leveling agent, 0.2-0.4 parts of substrate wetting agent, 0.2-0.5 parts of rheological aid and 8-13 parts of deionized water; The B component includes: 15-26 parts of isocyanate curing agent, 5-8 parts of propylene glycol diacetate, and 0.7-1.2 parts of silicone coupling agent.

[0006] In the hydroxylated acrylic dispersion, the mass content of hydroxyl groups is 3.9-4.2%.

[0007] In the graphene dispersion, the mass fraction of graphene is 2.5-5.5%.

[0008] The film-forming aid is at least one of dipropylene glycol butyl ether, propylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether acetate, and ethylene glycol monobutyl ether.

[0009] The isocyanate curing agent is sulfonate-modified hexamethylene diisocyanate.

[0010] The organic silicon coupling agent is an organic silicon oligomer containing epoxy functional groups; and the amine neutralizing agent is N~N-dimethylethanolamine.

[0011] The leveling agent is an acrylic polymer; the substrate wetting agent is an organic silicon polymer containing a gemini structure; and the dispersant is an aqueous solution of a polyether-modified styrene maleic anhydride copolymer containing a pigment affinity group.

[0012] The defoamer includes an organosilicon defoamer and a mineral polymer defoamer. The organosilicon defoamer is used in the slurry grinding stage; the mineral polymer defoamer is used in the paint mixing stage of component A.

[0013] The rheological additive is an associative polyurethane rheological additive, and the rheological additive includes a low shear rheological additive and a high shear rheological additive, and the mass ratio of the low shear rheological additive to the high shear rheological additive is (1~2):1.

[0014] The present invention also provides a method for preparing a high-gloss and high-water-resistant water-based acrylic polyurethane topcoat, comprising: Weigh each component according to the mass ratio of the high-gloss and high-water-resistant water-based acrylic polyurethane topcoat according to claim 1; Under stirring, deionized water, silicone defoamer, dispersant and graphene are added according to the formula amount and mixed evenly, and stirred until there is no dry powder, and then ground until the fineness is less than 5 microns to obtain a graphene dispersion; Under stirring, add deionized water, defoamer, dispersant, carbon black, sericite and precipitated barium sulfate according to the formula amount, mix evenly, and stir until there is no dry powder, then grind until the fineness is less than 15µm to obtain filler slurry; Under stirring, add hydroxy acrylic acid dispersion, amine neutralizer, film-forming aid, filler slurry, graphene dispersion, leveling agent, mineral polymer defoamer and substrate wetting agent according to the formula amount and mix evenly, then add rheological additive until the KU value is 90, and continue stirring until the mixture is evenly mixed; after stirring, filter to obtain component A for use; Under stirring, add propylene glycol diacetate, isocyanate curing agent and silicone coupling agent according to the formula amount, and continue stirring until the mixture is evenly mixed; after stirring, filter to obtain component B for use; When using, mix component A and component B evenly according to the mass ratio.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The high-gloss and high-water-resistant water-based acrylic polyurethane topcoat provided by the present invention is prepared into a graphene dispersion with good storage stability by selecting redox graphene with a two-dimensional sheet structure, and is matched with an acrylic dispersion with a high hydroxyl value content as component A. The addition of sericite in component A can effectively improve the gloss and flatness of the paint film; the tiny gaps between the sericite sheets can also play a certain buffering role, enhance the impact resistance and hardness of the coating, so that the topcoat has excellent mechanical properties while maintaining high gloss. Component A and hexamethylene diisocyanate modified by a special coupling agent as component B undergo a cross-linking reaction. The organosilicon oligomer containing epoxy functional groups in the special coupling agent associates with an isocyanate curing agent at one end, and the other end cross-links with polar groups such as ~OH on the surface of the coated object to improve the compactness of the paint film and the adhesion to the substrate, thereby improving the 40°C water resistance of the high-gloss and high-water-resistant water-based acrylic polyurethane topcoat, and the paint film has good impact resistance and artificial aging resistance. The product prepared by the present invention has a gloss of 87° at an angle of 20° and a gloss of 93.5° at an angle of 60°. The product has high gloss and can withstand 40°C water for 30 days, and the paint film remains intact without bubbling, stickiness or wrinkling. The good resistance to artificial aging also ensures that the topcoat can maintain its original gloss and mechanical strength under long-term outdoor exposure, thereby extending the service life of the coating.

[0016] Furthermore, the limited hydroxyl content can ensure sufficient reactivity between component A and component B, thereby ensuring the full cross-linking reaction, which not only improves the hardness and adhesion of the paint film, but also enhances the water resistance and weather resistance of the coating.

[0017] Furthermore, the graphene mass fraction ensures good dispersion of graphene in the coating, improving the durability and protection of the topcoat.

[0018] Furthermore, sulfonate-modified hexamethylene diisocyanate is used as a curing agent, which has strong reactivity and cross-linking properties and can react with the hydroxyl groups in the hydroxyl acrylic dispersion to form a cross-linking structure, thereby improving the chemical resistance, water resistance and aging resistance of the coating film. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown here can be arranged and designed by various different configurations. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0020] The present invention provides a high-gloss and high-water-resistant water-based acrylic polyurethane topcoat, comprising a component A and a component B, wherein the mass ratio of the component A to the component B is 100:(20-30); The component A comprises the following components in parts by weight: 45-65 parts of hydroxy acrylic dispersion, 0.2-0.5 parts of amine neutralizer, 5-8 parts of film-forming aid, 3-6 parts of graphene dispersion, 3-6 parts of dispersant, 1-3 parts of carbon black, 5-12 parts of precipitated barium sulfate, 2-5 parts of sericite, 0.3-0.6 parts of defoamer, 0.1-0.4 parts of leveling agent, 0.2-0.4 parts of substrate wetting agent, 0.2-0.5 parts of rheological aid, and 8-13 parts of deionized water; The B component includes the following components by mass: 15-26 parts of isocyanate curing agent, 5-8 parts of propylene glycol diacetate, and 0.7-1.2 parts of silicone coupling agent; In an embodiment of the present invention, the mass content of hydroxyl groups in the hydroxylated acrylic dispersion is 3.9-4.2%. In some embodiments, the hydroxylated acrylic dispersion is Antkote 2042 of Wanhua Chemical.

[0021] In the embodiment of the present invention, since the graphene type and dispersant used in the formula of the graphene dispersion will greatly affect the water resistance of the paint film, the graphene in the graphene dispersion is 806H / 003 of the Huazhou Branch of Shaanxi Coal Research Institute, which is an oxidized-reduced graphene with a large specific surface area and good dispersibility, and can block / prolong the bubbling and wrinkling caused by water passing through the coating. When the dispersant is BYK~2013, the obtained product has better water resistance. The mass fraction of the graphene dispersion is 2.5~5.5%. In an embodiment of the present invention, the amine neutralizer is N~N-dimethylethanolamine.

[0022] In an embodiment of the present invention, the film-forming aid is at least one of dipropylene glycol butyl ether, propylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether acetate, and ethylene glycol monobutyl ether; in some embodiments, the film-forming aid is a mixture of slow-drying diethylene glycol butyl ether acetate and fast-drying propylene glycol butyl ether, and the mass ratio of diethylene glycol butyl ether acetate:propylene glycol butyl ether is (1~1.5):1.

[0023] In an embodiment of the present invention, the defoaming agent is a silicone defoamer and a mineral polymer defoamer. In the water slurry grinding stage, a silicone defoamer with poor compatibility and strong defoaming property is selected, and in the paint mixing stage, a mineral polymer defoamer with good compatibility, poor defoaming property and insensitivity to pH is selected.

[0024] In an embodiment of the present invention, the dispersant is an aqueous solution of a polyether-modified styrene maleic anhydride copolymer containing a pigment affinity group, and 98.5% solid content has little effect on water resistance. In some embodiments, the dispersant is BYK~2013, which can significantly reduce the viscosity of the graphene dispersion and carbon black + filler slurry, and at the same time has a great improvement on the water resistance of the paint film.

[0025] In an embodiment of the present invention, the carbon black is Orilon medium-high pigment 45 carbon black; In an embodiment of the present invention, the precipitated barium sulfate is a precipitated barium sulfate with high purity and low oil absorption; In an embodiment of the present invention, the substrate wetting agent is a silicone polymer containing a twin structure; in some embodiments, the substrate wetting agent is Digo 4100, which can not only strongly reduce the surface tension of the paint liquid and improve the leveling of the paint film, but also is not easy to stabilize bubbles, and the paint film has no bubbles and has a high film thickness.

[0026] In an embodiment of the present invention, the leveling agent is an acrylic polymer. In some embodiments, the leveling agent is BYK~3455. Different types of leveling agents provide a certain leveling property during use and also bring about the side effect of stabilizing foam. Among them, the silicone leveling agent can strongly reduce the surface tension of the paint film, which will make the paint film level quickly but is relatively easy to stabilize foam. The acrylic BYK~3455 leveling agent has good leveling property and is not easy to stabilize foam.

[0027] In an embodiment of the present invention, the rheological additive is an associative polyurethane rheological additive, the rheological additive is a mixture of low shear and high shear, and the mass ratio of low shear rheological additive to high shear rheological additive is (1~2):1. In some embodiments, the rheological additive is a combination of high shear RM~2020 and low shear 105A; the high shear RM~2020 rheological additive does not contribute much to improving the anti-sagging property of the paint film and increasing the viscosity of the paint liquid, but it will significantly reduce the product of paint liquid splashing, thereby improving the construction environment and improving the use efficiency of the topcoat. The low shear 105A rheological additive has an excellent thickening effect, providing better paint film anti-sagging and paint liquid anti-settling properties.

[0028] In an embodiment of the present invention, the isocyanate curing agent is sulfonate-modified hexamethylene diisocyanate; the isocyanate curing agent is Aquolin269 hexamethylene diisocyanate with good water resistance produced by Wanhua Chemical.

[0029] The organosilicon coupling agent is an organosilicon oligomer containing epoxy functional groups.

[0030] The present invention also provides a method for preparing the high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, which specifically includes the preparation of a graphene dispersion, and the preparation of component A and component B.

[0031] Weigh each component according to the mass ratio of the above-mentioned high-gloss and high-water-resistant water-based acrylic polyurethane topcoat; Preparation of graphene dispersion: Add the formulated amount of deionized water to a clean cylinder, add ⅓ of the formulated amount of silicone defoamer, ⅓ of the dispersant, and graphene in sequence at a speed of 700-800 rpm, stir at a high speed of 2000-2500 rpm for 20-30 minutes until there is no dry powder, and then grind in a three-roll mill until the fineness is less than 5 microns to obtain a graphene dispersion; Preparation of filler slurry: Preparation of filler slurry: add the formulated amount of deionized water into a clean cylinder, start stirring, add ⅔ of the silicone defoamer, ⅔ of the dispersant, carbon black, precipitated barium sulfate and sericite in sequence at a speed of 700-800 rpm, disperse at a high speed of 1000-1100 rpm for 30-40 minutes, stir evenly until there is no dry powder, and set aside; Grinding of filler slurry: Grind the prepared slurry with a sand mill at high speed until it is below 15µm to obtain filler slurry. Place the filler slurry in a clean container and rinse the grinding equipment with clean water until the outlet water is clear and colorless. Preparation of component A: Paint mixing: Add the formulated amount of hydroxy acrylic dispersion into a clean paint mixing kettle, add the formulated amount of amine neutralizer, film-forming aid, ground filler slurry, ground graphene dispersion, leveling agent, mineral polymer defoamer, substrate wetting agent in sequence at a speed of 1200-1400 rpm and stir for 30-40 minutes, then add the rheological additive at a speed of 900-1000 rpm until the KU value is 90, and then stir for 30-40 minutes; Packaging: Filter the prepared paint liquid through 100-mesh silk to obtain component A, put the obtained component A into a packaging barrel and seal it.

[0032] Preparation of component B: Add propylene glycol diacetate to a clean container, add the formulated amount of isocyanate curing agent and silicone coupling agent in sequence at a speed of 700-800 rpm, then stir for 10-20 minutes, filter with 100-mesh silk and set aside.

[0033] When using, mix component A and component B according to the mass ratio.

[0034] In the following examples, unless otherwise specified, all materials used can be obtained through common channels; and the test methods adopted are conventional methods in the art.

[0035] Example 1 A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, comprising the components shown in Table 1: Table 1

[0036] Component A and component B are prepared according to the components in Table 3 and the preparation method provided by the present invention. When used, component A and component B are mixed in a mass ratio of 100:30.

[0037] Example 2 A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, comprising the components shown in Table 2: Table 2

[0038] Component A and component B are prepared according to the components in Table 2 and the preparation method provided by the present invention. When used, component A and component B are mixed in a mass ratio of 100:30.

[0039] Example 3 A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, comprising the components shown in Table 3: Table 3

[0040] Component A and component B are prepared according to the components in Table 1 and the preparation method provided by the present invention. When used, component A and component B are mixed in a mass ratio of 100:25.

[0041] Example 4 A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, comprising the components shown in Table 4: Table 4

[0042] Component A and component B were prepared according to the components in Table 4 and the preparation method provided by the present invention. When used, component A and component B were mixed in a mass ratio of 100:30.

[0043] The high gloss and high water resistance water-based acrylic polyurethane topcoat prepared in Examples 1 to 4 was subjected to performance tests, and the product performance indicators and test results are as follows: Performance test conditions: The coatings for testing appearance, adhesion, pencil hardness, flexibility and impact resistance were prepared on tinplate (120mm×50mm×0.3~0.5mm), gloss was prepared on glass (120mm×90mm×2~3mm), polishability was prepared on ordinary low-carbon steel (70mm×150mm×1mm), water resistance, acid resistance, alkali resistance and artificial aging resistance were prepared on steel (150mm×75mm×0.8~1mm), mechanical properties were tested with a coating thickness of 23±3µm, gloss was tested with a coating thickness of 45±5µm, and resistance was tested with a coating thickness of 55±10µm. The prepared samples were tested after 7 days of curing.

[0044] Table 1 Test results of paint film performance indicators of Examples 1 to 4

[0045] After performance testing, the water-based acrylic polyurethane topcoat coatings prepared in Examples 1 to 4 have no obvious defects in appearance. The paint film of Example 4 has a gloss of 87° at a 20° angle and a gloss of 93.5° at a 60° angle, and has high gloss. The paint film has excellent hardness and impact resistance, and the water resistance (40°C) paint film remains intact for 30 days. It has excellent test results in terms of acid and alkali resistance, wear resistance, and weather resistance.

[0046] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art can still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, characterized in that: It comprises component A and component B, wherein the mass ratio of component A to component B is 100:(20-30); The component A comprises: 45-65 parts of hydroxy acrylic acid dispersion, 0.2-0.5 parts of amine neutralizer, 5-8 parts of film-forming aid, 3-6 parts of graphene dispersion, 3-6 parts of dispersant, 1-3 parts of carbon black, 5-12 parts of precipitated barium sulfate, 2-5 parts of sericite, 0.3-0.6 parts of defoamer, 0.1-0.4 parts of leveling agent, 0.2-0.4 parts of substrate wetting agent, 0.2-0.5 parts of rheological aid and 8-13 parts of deionized water; The B component includes: 15-26 parts of isocyanate curing agent, 5-8 parts of propylene glycol diacetate, and 0.7-1.2 parts of silicone coupling agent.

2. A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: In the hydroxylated acrylic dispersion, the mass content of hydroxyl groups is 3.9-4.2%.

3. A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: In the graphene dispersion, the mass fraction of graphene is 2.5-5.5%.

4. A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The film-forming aid is at least one of dipropylene glycol butyl ether, propylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether acetate, and ethylene glycol monobutyl ether.

5. The high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The isocyanate curing agent is sulfonate-modified hexamethylene diisocyanate.

6. A high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The organic silicon coupling agent is an organic silicon oligomer containing epoxy functional groups; and the amine neutralizing agent is N~N-dimethylethanolamine.

7. The high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The leveling agent is an acrylic polymer; the substrate wetting agent is an organic silicon polymer containing a gemini structure; and the dispersant is an aqueous solution of a polyether-modified styrene maleic anhydride copolymer containing a pigment affinity group.

8. The high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The defoamer includes an organosilicon defoamer and a mineral polymer defoamer. The organosilicon defoamer is used in the slurry grinding stage; the mineral polymer defoamer is used in the paint mixing stage of component A.

9. The high-gloss and highly water-resistant water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The rheological additive is an associative polyurethane rheological additive, and the rheological additive includes a low shear rheological additive and a high shear rheological additive, and the mass ratio of the low shear rheological additive to the high shear rheological additive is (1~2):

1.

10. A method for preparing a high-gloss and highly water-resistant water-based acrylic polyurethane topcoat, characterized in that: include: Weigh each component according to the mass ratio of the high-gloss and high-water-resistant water-based acrylic polyurethane topcoat according to claim 1; Under stirring, deionized water, silicone defoamer, dispersant and graphene are added according to the formula amount and mixed evenly, and stirred until there is no dry powder, and then ground until the fineness is less than 5 microns to obtain a graphene dispersion; Under stirring, add deionized water, defoamer, dispersant, carbon black, sericite and precipitated barium sulfate according to the formula amount, mix evenly, and stir until there is no dry powder, then grind until the fineness is less than 15µm to obtain filler slurry; Under stirring, add hydroxy acrylic acid dispersion, amine neutralizer, film-forming aid, filler slurry, graphene dispersion, leveling agent, mineral polymer defoamer and substrate wetting agent according to the formula amount and mix evenly, then add rheological additive until the KU value is 90, and continue stirring until the mixture is evenly mixed; after stirring, filter to obtain component A for use; Under stirring, add propylene glycol diacetate, isocyanate curing agent and silicone coupling agent according to the formula amount, and continue stirring until the mixture is evenly mixed; after stirring, filter to obtain component B for use; When using, mix component A and component B evenly according to the mass ratio.

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