Waterborne polyurethane coating as well as preparation method and application thereof

Abstract

The invention discloses a waterborne polyurethane coating and a preparation method and application thereof, and belongs to the technical field of coatings, the waterborne polyurethane coating is characterized in that the waterborne polyurethane coating comprises a main agent and a curing agent, the weight ratio of the main agent to the curing agent is (4-8): 1, and the main agent, the curing agent and the main agent are mixed to form the waterborne polyurethane coating. Comprising the following raw materials in parts by weight: 50-60 parts of a water-based hydroxy acrylic dispersion, 0.5-1 part of a wetting leveling agent, 0.5-1 part of a surfactant, 1-5 parts of a coalescing agent, 0.1-2 parts of a thickening agent and 24-40 parts of deionized water. The waterborne polyurethane coating obtained by the invention can have good adhesive force on composite materials such as carbon fibers and glass fibers.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a water-based polyurethane coating, a preparation method and application thereof. BACKGROUND

[0002] With the continuous progress of global technology, the field of composite materials has made significant development. From carbon fiber reinforced unmanned aerial vehicle wings to lightweight structures made of glass fiber, the innovation of composite materials continues to inject momentum into the growth of the low-altitude economy. The close relationship between low-altitude economy and composite materials is fully reflected in technological progress and industrial upgrading. Especially in the context of the gradual relaxation of global policies in the low-altitude field and the continuous emergence of new materials and processes, the application of composite materials in low-altitude aircraft has ushered in unprecedented opportunities. The widespread application of composite materials in many fields not only promotes the development of related industries, but also provides new ways to solve problems that traditional materials cannot handle.

[0003] In solving the problem of carbon fiber protection and other related issues, there are already some coatings for carbon fiber on the market. These coatings can to some extent play a protective role on carbon fiber. Common methods include using some traditional coating formulas to form a protective film on the surface of carbon fiber. These coatings may be based on different chemicals and applied to the surface of carbon fiber by spraying, brushing and other methods. In addition, some coatings also add some special additives in order to improve the performance of the coating. However, these methods are attempts within the existing technical framework.

[0004] The existing coatings for carbon fiber have many defects. On the one hand, the existing coatings may not provide an ideal appearance effect, such as poor color uniformity, gloss and coating flatness, which may affect the overall visual appeal. On the other hand, the adhesion strength between the surface of carbon fiber and the coating may be insufficient, causing the coating to easily peel off or blister, affecting the durability and safety of the structure. Moreover, the current coatings have poor environmental resistance and show performance degradation after a certain period of water and salt spray resistance testing, which can easily lead to corrosion and damage of the structure after long-term use. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a water-based polyurethane coating, a preparation method and application thereof. The water-based polyurethane coating obtained by the present application can have good adhesion on composite materials such as carbon fiber and glass fiber.

[0006] The second aspect of the present application is to provide a water-based polyurethane coating, which adopts the following technical solution: An aqueous polyurethane coating, the polyurethane coating comprising a main agent and a curing agent, the weight ratio of the main agent to the curing agent being (4-8):1, the main agent comprising the following raw materials in parts by weight: 50-60 parts of an aqueous hydroxyl acrylic dispersion, 0.5-1 part of a wetting leveling agent, 0.5-1 part of a surfactant, 1-5 parts of a film forming aid, 0.1-2 parts of a thickening agent, and 24-40 parts of deionized water.

[0007] By adopting the above technical scheme, the cooperation between the aqueous hydroxyl acrylic dispersion and the wetting leveling agent, the surfactant, and the film forming aid can enhance the contact area of the coating with the surface of materials such as carbon fiber, glass fiber, and stainless steel, has good film forming property and chemical stability, promotes the close combination between the coating and the substrate, and the film forming aid helps the coating to form a uniform and dense film layer during the drying process, thereby effectively improving the adhesion between the film layer and the substrate; the thickening agent can adjust the rheological property of the coating, so that the coating is better attached to the surface of the material, prevents the coating from flowing or dripping during the construction process, and ensures the integrity and uniformity of the film layer.

[0008] In the present application, the curing ratio of the main agent to the curing agent is (4-8):1, especially in the range of 4-6:1, which can ensure complete reaction, fast curing speed, and optimal material performance after curing, and this ratio range can ensure the activity of the reaction, the viscosity of the material, and the physical and chemical properties of the final product.

[0009] Preferably, the aqueous hydroxyl acrylic dispersion is composed of HDT 12 and HDT 16 in a weight ratio of 1:(1-5).

[0010] By adopting the above technical scheme, the aqueous hydroxyl acrylic dispersion is composed of HDT 12 and HDT 16 in a weight ratio of 1:(1-5), which can form a good synergistic effect between the two components, so that the coating has better compatibility and affinity with the surface of materials such as carbon fiber. When the coating is applied to the surface of the material, HDT 12 and HDT 16 can more closely combine with the molecules on the surface of the material, enhancing the intermolecular interaction force, thereby making the adhesion of the coating to the surface of the material better, effectively avoiding the peeling or blistering of the coating, and improving the durability and safety of the structure.

[0011] If the aqueous hydroxyl acrylic dispersion only adopts HDT 12, the coating is too soft and has poor protective effect, and if it only adopts HDT 16, the coating is too hard and has weak impact resistance, and is also prone to cracking, cracking, or peeling, therefore, HDT 12 is used in cooperation with When HDT 16 is used in cooperation with HDT 12, not only can the adhesion of the paint be effectively improved, but also the water resistance and salt mist resistance of the coating can be guaranteed.

[0012] Preferably, the wetting and leveling agent is an organic silicon surface active leveling agent, preferably BYK-346, which has good substrate wetting ability, effectively reduces the surface tension of the paint, does not produce foam stabilization, does not increase the surface smoothness, and does not damage the re-coatability.

[0013] Preferably, the surfactant is an organic silicon super-spreading surfactant, preferably Miti Silwet L-77, which can promote target wetting through pore penetration to obtain excellent performance in final application and improve the adhesion of the coating.

[0014] Preferably, the film-forming aid is composed of diethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:(1.5-2.5).

[0015] By using the above technical solution, using a film-forming aid composed of diethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:(1.5-2.5), the water-based polyurethane paint can slowly volatilize the solvent during the film-forming process, thereby forming a uniform, dense and continuous coating, improving the gloss and flatness of the coating, and improving the appearance effect of the paint; at the same time, it helps to enhance the adhesion strength of the paint to the surface of carbon fiber, so that the coating is not easy to peel off or blister, and the durability and safety of the structure are improved; it also improves the environmental resistance of the paint, so that it performs better in water resistance and salt mist resistance tests, and reduces the corrosion and damage of the structure after long-term use.

[0016] Preferably, the thickening agent is an associated polyurethane thickening agent.

[0017] Preferably, the curing agent is a compounded curing agent, which is mixed by isocyanate trimer and propylene glycol methyl ether acetate in a weight ratio of 1.5:1.

[0018] By using the above technical solution, the compounded curing agent can cause the paint to undergo cross-linking and curing reaction, forming a firm three-dimensional network structure, further enhancing the adhesion of the paint to the surface of carbon fiber, glass fiber and stainless steel material, thereby improving the adhesion of the water-based polyurethane paint on these materials.

[0019] The complex curing agent is mixed by isocyanate trimer and propylene glycol methyl ether acetate according to a weight ratio of 1.5:1, can make the water-based polyurethane coating have better curing effect, improve the bonding strength between the carbon fiber surface and the coating, avoid coating peeling or blistering, improve the durability and safety of the structure; meanwhile, the environmental resistance of the coating can also be improved, and the coating can still maintain good performance after long-time water resistance and salt mist resistance test, prevent corrosion and damage of the structure after long-term use, and help to improve the appearance effect of the coating, make the color more uniform, gloss better, and coating more flat.

[0020] The second aspect of the present application is to provide a preparation method of the water-based polyurethane coating as described above, comprising the following steps: S1, adding a wetting and leveling agent, a surfactant, a film-forming aid, a thickening agent, and deionized water in sequence to the water-based hydroxyl acrylic dispersion, and stirring and mixing uniformly to obtain component A; S2, mixing the components in the complex curing agent to obtain component B; S3, mixing component A and component B to obtain the water-based polyurethane coating.

[0021] The third aspect of the present application is to provide an application of the water-based polyurethane coating as described above, and the water-based polyurethane coating is used for surface protection of carbon fiber materials, glass fiber materials, and stainless steel materials.

[0022] In summary, the present application has the following beneficial effects: The present application can obtain a coating with good adhesion, water resistance, salt mist resistance, self-drying, environmental protection, and convenient construction on carbon fiber, glass fiber, and stainless steel materials by selecting appropriate water-based hydroxyl acrylic dispersion, organic silicon super-spreading surfactant, and synergistic matching of the complex curing agent. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in combination with examples. All reagents not specified by the manufacturer are conventional reagent products that can be obtained by purchase in the market.

[0024] Example 1 A water-based polyurethane coating includes component A and component B, and the weight ratio of component A and component B is 4:1, wherein component A includes the following raw materials: The water-based hydroxyl acrylic dispersion is 55 kg, the wetting and leveling agent BYK-346 is 0.5 kg, the organic silicon super-spreading surfactant is 1 kg, the film-forming aid is 3 kg, the thickening agent Borchi Gel 0620 is 1 kg, and the deionized water is 30 kg, wherein the water-based hydroxyl acrylic dispersion is mixed by HDT 12 and HDT 12 according to a weight ratio of 1:1. HDT 12 and HDT 16 consists of, HDT 12 and HDT 16 are both purchased from Huntsman Corporation; The film forming aid is composed of diethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:2; The B component includes the following raw materials in weight percentage: isocyanate curing agent N3900 is 60%, propylene glycol methyl ether acetate is 40%; The preparation method of the water-based polyurethane coating includes the following steps: S1, to the water-based hydroxyl acrylic dispersion, add wetting and leveling agent BYK-346 while stirring, stir at a rate of 200 r / min for 10 min, then add diethylene glycol butyl ether and dipropylene glycol butyl ether, stir at a rate of 200 r / min for 10 min, add silicone-based super spreading surfactant Migu Silwet L-77 thickening agent, stir at a rate of 200 r / min for 20 min, add thickening agent Borchi Gel 0620, stir at a rate of 300 r / min for 30 min, and finally add deionized water, stir at a rate of 200 r / min for 10 min to mix evenly to obtain the A component; S2, mix isocyanate curing agent N3900 and propylene glycol methyl ether acetate to obtain the B component; When used, the A component and the B component are mixed in a curing ratio of 4:1.

[0025] Example 2 A water-based polyurethane coating includes an A component and a B component, and the weight ratio of the A component to the B component is 5:1, wherein the A component includes the following raw materials: Water-based hydroxyl acrylic dispersion 50 kg, wetting and leveling agent BYK-346 0.8 kg, silicone-based super spreading surfactant Migu Silwet L-77 0.8 kg, film forming aid 1 kg, thickening agent Borchi Gel 0620 0.1 kg, and deionized water 25 kg, wherein the water-based hydroxyl acrylic dispersion is composed of HDT 12 and HDT16 consists of, HDT 12 and HDT 16 are both purchased from Huntsman Corporation; The film forming aid is composed of diethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:1.5; The B component includes the following raw materials in weight percentage: isocyanate curing agent N3900 is 60%, propylene glycol methyl ether acetate is 40%; The preparation method of the water-based polyurethane coating includes the following steps: S1, to the water-based hydroxyl acrylic dispersion, wetting and leveling agent BYK-346 is added while stirring, stirring at a rate of 200 r / min for 10 min, then diethylene glycol butyl ether and dipropylene glycol butyl ether are added, stirring at a rate of 200 r / min for 10 min, silicone-based super-spreading surfactant Silwet L-77 thickening agent is added, stirring at a rate of 200 r / min for 20 min, thickening agent Borchi Gel 0620 is added, stirring at a rate of 300 r / min for 30 min, finally deionized water is added, stirring at a rate of 200 r / min for 10 min, and stirring until uniform to obtain component A; S2, isocyanate curing agent N3900 and propylene glycol methyl ether acetate are mixed to obtain component B; When used, components A and B are mixed in a curing ratio of 5:1.

[0026] Example 3 A water-based polyurethane coating includes component A and component B, and the weight ratio of component A to component B is 8:1, wherein component A includes the following raw materials: Water-based hydroxyl acrylic dispersion 60 kg, wetting and leveling agent BYK-346 1 kg, silicone-based super-spreading surfactant Silwet L-77 0.5 kg, film-forming aid 5 kg, thickening agent Borchi Gel 0620 2 kg, and deionized water 40 kg, wherein the water-based hydroxyl acrylic dispersion is composed of HDT 12 and HDT 16, HDT 12 and HDT 16 are all purchased from Xitama Company; The film-forming aid is composed of diethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:2.5; Component B includes the following raw materials in the following weight percentages: isocyanate curing agent N3900 60%, propylene glycol methyl ether acetate 40%; A method for preparing a water-based polyurethane coating includes the following steps: S1, to the water-based hydroxyl acrylic dispersion, wetting and leveling agent BYK-346 is added while stirring, stirring at a rate of 200 r / min for 10 min, then diethylene glycol butyl ether and dipropylene glycol butyl ether are added, stirring at a rate of 200 r / min for 10 min, silicone-based super-spreading surfactant Silwet L-77 thickening agent is added, stirring at a rate of 200 r / min for 20 min, thickening agent Borchi Gel 0620 is added, stirring at a rate of 300 r / min for 30 min, finally deionized water is added, stirring at a rate of 200 r / min for 10 min, and stirring until uniform to obtain component A; S2, mixing isocyanate curing agent N3900 and propylene glycol methyl ether acetate to obtain component B; In use, component A and component B are mixed in a curing ratio of 8:1.

[0027] Comparative Example 1 A water-based polyurethane coating, which is different from Example 1 in that the water-based hydroxyl acrylic dispersion is EMS9300 of Holram Paint, and the others are the same as Example 1.

[0028] Comparative Example 2 A water-based polyurethane coating, which is different from Example 1 in that the water-based hydroxyl acrylic dispersion is only HDT 12 of Xitama, and the others are the same as Example 1. HDT 12, and the others are the same as Example 1.

[0029] Comparative Example 3 A water-based polyurethane coating, which is different from Example 1 in that the water-based hydroxyl acrylic dispersion is only HDT 16 of Xitama, and the others are the same as Example 1. HDT 16, and the others are the same as Example 1.

[0030] Performance Test The water-based polyurethane coatings obtained in the above examples and comparative examples are respectively coated on the surface of the material to form a paint film, and after self-drying for 7 days, the adhesion, water resistance, salt spray resistance and ultraviolet aging experiments are carried out, and the test results are shown in Table 1.

[0031] Among them, the adhesion test is tested according to the relevant provisions in GBT9286-1998 "Paint and Varnish Film Scratch Test", and the water-based polyurethane coating is respectively coated on the surface of carbon fiber, glass fiber and stainless steel to test the adhesion, and 0 level is the best, and 5 level is the worst; The water resistance test is tested according to the relevant provisions in GB9274-1988 "Determination of Liquid Medium Resistance of Paint and Varnish", and the test condition is tested in water at 40℃ for 240h; The neutral salt spray test is tested according to the relevant provisions in GBT1771-2007 "Determination of Neutral Salt Spray Resistance of Paint and Varnish", and the test time is 300h; The ultraviolet aging experiment is tested according to the relevant provisions in GBT1865-2009 "Artificial Climate Aging and Artificial Radiation Exposure Filtered Xenon Arc Radiation of Paint and Varnish", and the test time is 2000h, wherein 0 level is no powder phenomenon, 1 level is slight powdering (a small amount of white powder appears on the surface), 2 level is obvious powdering (more white powder appears on the surface), 3 level is serious powdering (a large amount of white powder falls off from the surface), and 4 level is complete powdering (the coating completely falls off).

[0032] The waterborne polyurethane coating obtained by the embodiments of the present application has basically the same results of water resistance, neutral salt spray test and ultraviolet aging test on the surface of carbon fiber, glass fiber and stainless steel, so the results of water resistance, neutral salt spray test and outdoor aging test in Table 1 are exemplified by the results of coating on the surface of stainless steel, and the test results of the surface of stainless steel in Comparative Example 1 are exemplified.

[0033] Table 1: Test results of waterborne polyurethane coating performance In Comparative Examples 2 and 3, since the single waterborne hydroxyl acrylic dispersion HDT 12 or HDT 16 is used while other formulations remain unchanged, the coating obtained by the former is too soft, and the coating obtained by the latter is too hard, so that film formation is impossible, and therefore the adhesion, water resistance, salt spray resistance and ultraviolet aging resistance cannot be tested, which further illustrates that the cooperation of the waterborne hydroxyl acrylic dispersion HDT 12 and HDT 16 is the basis for ensuring that the waterborne polyurethane coating has good adhesion and water and salt spray resistance.

[0034] In Examples 1-3, by adjusting the content of each raw material in the main agent and the ratio of the waterborne hydroxyl acrylic dispersion HDT 12 and HDT 16, and the ratio of diethylene glycol butyl ether and dipropylene glycol butyl ether in the film forming aid, the waterborne polyurethane coatings of Examples 1-3 obtained have excellent adhesion on the surface of carbon fiber, glass fiber and stainless steel, and the adhesion is all 0 grade, which illustrates that the waterborne polyurethane coating obtained by the present application can be closely combined with the surface of carbon fiber, glass fiber and stainless steel.

[0035] Moreover, after the waterborne polyurethane coatings obtained by Examples 1-3 are tested in water at 40℃ for 240 hours, the board surface is free of blistering and water whitening, which illustrates that the waterborne polyurethane coatings obtained by Examples 1-3 have good water resistance.

[0036] The salt spray resistance of the waterborne polyurethane coating obtained in Example 1-2 is 1mm of rust width, no bubbles, and the ultraviolet aging resistance is level 2, indicating that the overall formula of the waterborne polyurethane coating obtained in Example 1-2 has good salt spray resistance and ultraviolet aging resistance. The salt spray resistance and ultraviolet aging resistance of the waterborne polyurethane coating obtained in Example 3 are lower than those of Example 1-2, the main reason is that the curing ratio of the main agent and the curing agent in Example 3 is 8:1, the reduction of the content of the curing agent makes the curing reaction not complete enough, and the crosslinking density is insufficient, thereby affecting the salt spray resistance and ultraviolet aging resistance of the coating. It is also further indicated that when the curing ratio is <8:1, the waterborne polyurethane coating has good salt spray resistance and ultraviolet aging resistance.

[0037] Compared with Example 1, when the waterborne hydroxyl acrylic dispersion is EMS9300 of Haolisen Coatings, the adhesion of the waterborne polyurethane coating obtained in Comparative Example 1 on carbon fiber is level 5, on glass fiber is level 3, and on stainless steel is level 2, indicating that the adhesion of the waterborne polyurethane coating obtained in Comparative Example 1 on carbon fiber, glass fiber and stainless steel surface is significantly lower than that of Example 1, especially the adhesion on carbon fiber is worse. In addition, the water resistance and salt spray resistance of the waterborne polyurethane coating obtained in Comparative Example 1 are lower than those of Example 1, and the ultraviolet aging resistance is basically the same as that of Example 1, which further indicates that when the waterborne hydroxyl acrylic dispersion is composed of HDT 12 and HDT 16, the water resistance and salt spray resistance of the waterborne polyurethane coating can be effectively improved.

[0038] The examples of the specific embodiment are the preferred embodiments of the present application, but do not limit the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. An aqueous polyurethane coating, characterized by: The polyurethane coating comprises a main agent and a curing agent, the weight ratio of the main agent to the curing agent is (4-8):1, the main agent comprises the following raw materials in parts by weight: 50-60 parts of water-based hydroxyl acrylic dispersion, 0.5-1 part of wetting leveling agent, 0.5-1 part of surfactant, 1-5 parts of film forming aid, 0.1-2 parts of thickening agent, and 24-40 parts of deionized water.

2. The waterborne polyurethane coating according to claim 1, characterized in that: The aqueous hydroxyl acrylic dispersion is by PLIOTEC ® HDT 12 with PLIOTEC ® HDT 16 is composed of 1: (1-5) by weight.

3. The waterborne polyurethane coating of claim 1, wherein: The wetting leveling agent is a silicone surfactant leveling agent.

4. The waterborne polyurethane coating of claim 1, wherein: The surfactant is a silicone super spreading surfactant.

5. The waterborne polyurethane coating of claim 1, wherein: The film forming aid is composed of diethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:(1.5-2.5).

6. The waterborne polyurethane coating of claim 1, wherein: The thickening agent is an associated polyurethane thickening agent.

7. The waterborne polyurethane coating of claim 1, wherein: The curing agent is a compounded curing agent, which is obtained by mixing isocyanate trimer and propylene glycol methyl ether acetate in a weight ratio of 1.5:

1.

8. A process for the preparation of an aqueous polyurethane coating as claimed in any of claims 1 to 7, characterized in that The method comprises the following steps: S1, adding the wetting leveling agent, the surfactant, the film forming aid, the thickening agent and the deionized water into the water-based hydroxyl acrylic dispersion in sequence, and stirring and mixing to obtain an A component; S2, mixing the components in the curing agent to obtain a B component; S3, mixing the A component and the B component to obtain the water-based polyurethane coating.

9. Use of an aqueous polyurethane coating as claimed in any of claims 1 to 7, characterized in that: The water-based polyurethane coating is used for surface protection of carbon fiber material, glass fiber material and stainless steel material.

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