Water-based zero-VOC (volatile organic compound) coating as well as preparation method and application thereof

Abstract

The invention relates to a water-based zero-VOC (volatile organic compound) coating as well as a preparation method and application thereof. The water-based zero-VOC coating is prepared from a component A and a component B, wherein the mass ratio of the component A to the component B is (11: 1)-(12: 1); wherein the component A is prepared from the following components in parts by mass: 27 to 35 parts of low-hydroxyl acrylate dispersoid, 27 to 35 parts of polyurethane dispersoid, 1 to 2 parts of wetting dispersant, 0.1 to 0.3 part of defoaming agent, 17 to 27 parts of pigment filler, 0.05 to 0.2 part of color paste and 1 to 4 parts of delustering agent; the water-based ink comprises the following components in parts by weight: 30-50 parts of water-based ink, 0.3-1 part of a substrate wetting agent, 0.3-1 part of an ultraviolet light absorber, 0.3-1 part of a light stabilizer, 0.1-0.4 part of a thickening agent and 3-12 parts of deionized water. And the component B is a hexamethylene diisocyanate curing agent. No solvent is added into the coating, the VOC content is zero, and harmful substances such as heavy metal, benzene and formaldehyde are not contained.

Description

Technical Field

[0001] This application relates to the field of coating technology, and more particularly to a water-based zero-VOC coating, its preparation method, and its application. Background Technology

[0002] Wind power, as a green new energy source, has seen rapid application and development in the early 21st century. Wind turbine blades, as a crucial component of wind turbines, primarily capture wind energy to drive the generator set for power generation. Currently, most wind turbine blades are made of composite materials such as glass fiber reinforced epoxy resin or unsaturated polyester. When operating at high speeds, the linear velocity at the blade tip can reach 80 m / s, equivalent to the top speed of an F1 race car. Furthermore, they are affected by the environment: atmospheric corrosion, ultraviolet radiation, heavy rain, and dust storms. In cold regions, ice and snow can also accumulate, increasing the blade's mass and affecting power generation efficiency. Unprotected blades exposed to these harsh conditions may break in severe cases. This necessitates coatings with excellent weather resistance, salt spray resistance, chemical resistance, adhesion, a certain degree of deformation capacity, and resistance to mechanical fatigue failure. The function of the wind turbine blade topcoat coating is to protect the substrate from wear during operation and corrosion from ultraviolet radiation, windblown sand, and rainwater, fulfilling its primary protective function. However, existing water-based topcoats for wind turbine blades have the following limitations: high VOC content, low elongation, poor chemical corrosion resistance, and poor weather resistance, which cannot meet the needs of harsh environments such as land and sea in China.

[0003] Therefore, there is a need for an improved water-based zero-VOC coating for wind turbine blades and its preparation method. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0005] In one aspect, this application provides a water-based zero-VOC coating, wherein the raw materials of the water-based zero-VOC coating are composed of component A and component B, and the mass ratio of component A to component B is 11:1-12:1; wherein: Component A, by weight, comprises 27-35 parts of low-hydroxyl acrylate dispersion, 27-35 parts of polyurethane dispersion, 1-2 parts of wetting and dispersing agent, 0.1-0.3 parts of defoamer, 17-27 parts of pigments and fillers, 0.05-0.2 parts of color paste, 1-4 parts of matting agent, 0.3-1 parts of substrate wetting agent, 0.3-1 parts of ultraviolet absorber, 0.3-1 parts of light stabilizer, 0.1-0.4 parts of thickener, and 3-12 parts of deionized water; Component B is an aqueous hexamethylene diisocyanate curing agent.

[0006] In an exemplary embodiment, the low-hydroxyl acrylate dispersion has a solid content of 38-42 wt% and a hydroxyl content of 1.5%-1.8%.

[0007] In one exemplary embodiment, the polyurethane dispersion has a solid content of 50-54 wt% and a hydroxyl value of 62.7.

[0008] In one exemplary embodiment, the low-hydroxy acrylate dispersion is a self-crosslinking hydroxy acrylate dispersion.

[0009] In one exemplary embodiment, the polyurethane dispersion is a polycarbonate-type polyurethane dispersion.

[0010] In one exemplary embodiment, the polyurethane dispersion is an aliphatic hydroxyl-functionalized polycarbonate type polyurethane dispersion. For example, Houxian® 5757, purchased from Guangdong Huaguoshan Environmental Protection Technology Co., Ltd., is a milky white liquid with an OH content of 1.9% and a solid content of 52 ± 2 wt%.

[0011] In an exemplary embodiment, the low-hydroxy acrylate dispersion is a self-crosslinking hydroxy acrylate dispersion, such as Houxian®2046 purchased from Guangdong Huaguoshan Environmental Protection Technology Co., Ltd., which is a milky white semi-permeable emulsion with an OH content of 1.5% and a solid content of 40±1 wt%.

[0012] In one exemplary embodiment, the hexamethylene diisocyanate (HDI) curing agent may be Wanhua's Aquolin 269A.

[0013] In one exemplary embodiment, the wetting and dispersing agent is an aqueous dispersant.

[0014] In an exemplary embodiment, the defoamer is one or more of mineral oils, organosilicones, and polyethers.

[0015] In one exemplary embodiment, the pigment / filler is titanium dioxide.

[0016] In an exemplary embodiment, the matting agent is an aqueous matting powder.

[0017] In one exemplary embodiment, the substrate wetting agent is an aqueous substrate wetting agent.

[0018] In one exemplary embodiment, the ultraviolet absorber is a benzotriazole ultraviolet absorber.

[0019] In one exemplary embodiment, the light stabilizer is a hindered amine light stabilizer.

[0020] In one exemplary embodiment, the thickener is a nonionic associative thickener.

[0021] In one exemplary embodiment, the pigment / filler is rutile titanium dioxide.

[0022] In one exemplary embodiment, the titanium dioxide is a highly weather-resistant rutile titanium dioxide.

[0023] In one exemplary embodiment, the substrate wetting agent is an organosilicon twin structure surfactant.

[0024] In another aspect, a method for preparing the above-mentioned waterborne zero-VOC coating is provided, comprising the following steps: 1) Preparation of component A: a. According to the raw material ratio, add wetting and dispersing agent, defoamer, pigments and fillers to deionized water under stirring, mix and grind to obtain pigment slurry for later use; b. According to the raw material ratio, the polyurethane dispersion, low hydroxyl acrylate dispersion, pigment paste, substrate wetting agent, matting agent, ultraviolet absorber, light stabilizer, color paste and thickener are mixed and stirred evenly, and then filtered to obtain component A. 2) Preparation of component B: The cured agent, when filtered, becomes component B; 3) Mix component A and component B according to the mass ratio and stir until homogeneous to obtain the water-based zero-VOC coating.

[0025] In an exemplary embodiment, the preparation of component A includes... a. According to the raw material ratio, add deionized water to the first container, and add the wetting and dispersing agent and the defoamer while stirring. After stirring evenly, add the pigments and fillers and continue stirring evenly. Then grind to obtain the pigment and filler slurry for later use. The fineness of the pigment and filler slurry is ≤20μm. b. According to the raw material ratio, add the polyurethane dispersion and the low-hydroxy acrylate dispersion to the second container, mix and stir evenly; then add the pigment paste, the substrate wetting agent, the matting agent, the ultraviolet absorber, the light stabilizer, the color paste and the thickener while stirring, stir evenly, filter and package to obtain component A.

[0026] In another aspect, an application is provided for the above-described waterborne zero-VOC coating or the waterborne zero-VOC coating prepared according to the above method in high-toughness, high-weather-resistant products, wherein the products are wind turbine blades or housings; the waterborne zero-VOC coating can be used as a primer or topcoat.

[0027] In another aspect, a coating is provided formed from the above-described waterborne zero-VOC coating or a waterborne zero-VOC coating prepared according to the above method, wherein the coating is formed by applying the waterborne zero-VOC coating onto a substrate and curing it; wherein the substrate is a wind turbine blade or a casing.

[0028] The water-based zero-VOC coating of this application is a water-based system that does not contain any solvents. It has zero VOC content and does not contain harmful substances such as heavy metals, benzene, and formaldehyde, thus reducing environmental pollution and making it easy to apply.

[0029] The waterborne zero-VOC coating of this application uses a specific polyurethane dispersion and a low-hydroxyl acrylate dispersion. The low-hydroxyl acrylate dispersion has the advantages of fast drying, good gloss and color retention, and good gloss, hardness, adhesion and weather resistance. Its disadvantages are high minimum film-forming temperature, poor film-forming properties and flexibility, poor water and solvent resistance, and hot tack and cold brittleness. The molecular structure of the polyurethane dispersion is a segmental structure composed of hard and soft segments. This molecular structure determines its properties of being both hard and flexible. Its microscopic two-phase structure gives it excellent low-temperature film-forming properties, flexibility and leveling properties, and good heat resistance and tack resistance, but it is lacking in drying properties and gloss retention. By mixing polyurethane dispersion and low-hydroxy acrylate dispersion in a certain proportion, and combining self-crosslinking and curing crosslinking, the indispensable role of each resin is brought into play, forming a network coating film. This can make up for the deficiencies of polyurethane dispersion and low-hydroxy acrylate dispersion. The prepared coating does not require the addition of film-forming aids, has excellent leveling properties, and also has high elasticity, weather resistance, salt spray resistance, abrasion resistance, chemical resistance, and excellent mechanical properties. It also dries very quickly.

[0030] The curing agent used in the waterborne zero-VOC coating of this application is a waterborne curing agent. The waterborne curing agent has a certain degree of hydrophilicity and can be well dispersed in the waterborne system under low-speed stirring. It can be uniformly crosslinked and cured with polyurethane dispersion and low-hydroxyl acrylate dispersion to ensure the performance of the coating and good film leveling.

[0031] The water-based zero-VOC coating of this application does not require the use of film-forming substances. Instead, it only requires the compounding of two resins as film-forming substances, along with curing agents, pigments, fillers, ultraviolet absorbers, light stabilizers, etc., which makes the coating highly weather-resistant (UVB-313) up to 2000h, and the paint film does not bubble, peel, or chalk.

[0032] The substrate wetting agent described in this application is an organosilicon twin structure surfactant, which greatly reduces the surface tension of the system, provides excellent wetting and leveling capabilities, and enables the paint film to be evenly distributed on the substrate surface, thereby improving the leveling and adhesion of the paint film.

[0033] The coating applied in this application can be applied by spraying, brushing, or roller coating processes, and has good anti-sagging properties.

[0034] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application may be realized and obtained by means of the methods described in the description. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application are described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0036] The present invention will be further described in detail below with reference to specific examples, but these examples should not be construed as limiting the present invention.

[0037] Unless otherwise specified, all materials used in the following examples and comparative examples are commercially available.

[0038] Example In Examples 1 to 3, the formulations of components A and B of the waterborne zero-VOC coatings are shown in Table 1 below.

[0039] Table 1 In the formulations of Examples 1 to 3, the polyurethane dispersion and the low-hydroxyl acrylate dispersion were Houxian® 5757 and Houxian® 2046, respectively; the curing agent was Wanhua's Aquolin 269A; the pigment and filler titanium dioxide was Chemours rutile titanium dioxide R706; the light stabilizer was BASF 292; the ultraviolet absorber was BASF 1130; the wetting and dispersing agent was BYK's DISPERBYK-190; the defoamer was BASF Foamstar ST2410; the color paste was Shimin SIP3070 black paste; the matting agent was Lingwei Technology's TSA-260 N; the substrate wetting agent was TEGO® Twin 4100; and the thickener was Rohm and Haas RM-8W.

[0040] In the formulations of Examples 1 to 3 of this application, no film-forming aids are added, but the paint film has good leveling properties and possesses elasticity, weather resistance, salt spray resistance, abrasion resistance, chemical resistance, and excellent mechanical properties.

[0041] The preparation methods of water-based zero-VOC coatings in Examples 1 to 3 are as follows: 1) Preparation of component A: a. According to the raw material ratio, add the prescribed amount of deionized water to the mixing bowl, and add the wetting and dispersing agent and defoamer while stirring. After stirring evenly, slowly add the pigments and fillers to the mixing bowl and continue stirring evenly. Then put it into a sand mill for grinding to obtain the pigment and filler slurry for later use. The fineness of the pigment and filler slurry should be ≤20μm. b. According to the raw material ratio, add polyurethane dispersion and low hydroxyl acrylate dispersion to the paint mixing basin, mix and stir evenly; then, while stirring, slowly add pigment paste, substrate wetting agent, matting agent, ultraviolet absorber, light stabilizer, color paste and thickener to the paint mixing basin, stir evenly and filter to obtain component A.

[0042] 2) Preparation of component B: The cured agent, when filtered, becomes component B; 3) Mix component A and component B according to the mass ratio and stir evenly to obtain water-based zero VOC coating.

[0043] The performance of the water-based zero-VOC coatings prepared in Examples 1 to 3 was tested, and the test results are shown in Table 2 below.

[0044] Table 2 As shown in Table 2, the coatings prepared in Examples 1 to 3 all met or exceeded the performance requirements of wind turbine blade coatings when tested according to international standards.

[0045] As shown in Table 2, the coatings prepared in Examples 1 to 3 have an artificial aging resistance (UVB313) of 2000h, no bubbling or chalking, and a gloss retention rate of over 80%.

[0046] According to Table 2, from Example 1 to Example 3, in terms of drying rate: Example 1 was surface-dried for 20 minutes and fully dried for 3 hours; Example 2 was surface-dried for 15 minutes and fully dried for 2.5 hours; Example 3 was surface-dried for 25 minutes and fully dried for 4 hours. Example 2 dried the fastest, and Example 3 dried the slowest. In terms of elongation at break: Example 1 was 41%, Example 2 was 30%, and Example 3 was 43%. Example 3 had the highest elongation at break; Example 1 had the best overall performance.

[0047] Comparative Example This application also provides comparative examples 1 to 4, the formulations of which are shown in Table 3 below.

[0048] Table 3 In Comparative Example 1: The polyurethane dispersion and the low-hydroxyl acrylate dispersion are Houxian®5757 and Houxian®2046, respectively. The wetting and dispersing agent is DISPERBYK-190; The defoamer is TEGO 901W; The pigment and filler is Chemours rutile titanium dioxide R706; The colorant used is Shih Ming's SIP3070 black pigment; The film-forming aid is Eastman Chemical Company of the United States; The matting agent is TSA260 from Lingwei Technology Co., Ltd.; The substrate wetting agent is TEGO4100; The ultraviolet absorber is BASF 1130; The light stabilizer is BASF292; The thickener is Rohm and Haas's RM-8W; The curing agent HDI trimer is Wanhua's Aquolin 269A.

[0049] In Comparative Example 2: The polyurethane dispersion and the low-hydroxyl acrylate dispersion are Houxian®5757 and Houxian®2046, respectively. The wetting and dispersing agent is DISPERBYK-190; The defoamer is TEGO 901W; The pigment and filler is Chemours rutile titanium dioxide R706; The colorant used is Shih Ming's SIP3070 black pigment; The film-forming aid is Dow's DB; The matting agent is TSA260 from Lingwei Technology Co., Ltd.; The substrate wetting agent is TEGO4100; The ultraviolet absorber is BASF 1130; The light stabilizer is BASF292; The thickener is Rohm and Haas's RM-8W; The curing agent HDI trimer is Wanhua's Aquolin 269A.

[0050] In Comparative Example 3: The polyurethane dispersion and the low-hydroxyl acrylate dispersion are Houxian®5757 and Houxian®2046, respectively. The wetting and dispersing agent is DISPERBYK-190; The defoamer is TEGO 901W; The pigment and filler is Chemours rutile titanium dioxide R706; The colorant used is Shih Ming's SIP3070 black pigment; The film-forming aid is Dow's DPNB; The matting agent is TSA260 from Lingwei Technology Co., Ltd.; The substrate wetting agent is TEGO4100; The ultraviolet absorber is BASF 1130; The light stabilizer is BASF292; The thickener is Rohm and Haas's RM-8W; The curing agent HDI trimer is Wanhua's Aquolin 269A.

[0051] In Comparative Example 4: The polyurethane dispersion and the low-hydroxyl acrylate dispersion are Wanhua's Crysol® 6526 and Shiquanxing's 2218, respectively. The wetting and dispersing agent is DISPERBYK-190; The defoamer is TEGO 901W; The pigment and filler is Chemours rutile titanium dioxide R706; The colorant used is Shih Ming's SIP3070 black pigment; The film-forming aid is Dow's ethylene glycol butyl ether; The matting agent is TSA260 from Lingwei Technology Co., Ltd.; The substrate wetting agent is TEGO4100; The ultraviolet absorber is BASF 1130; The light stabilizer is BASF292; The thickener is Rohm and Haas's RM-8W; The curing agent HDI trimer is TPA100 from Asahi Kasei Corporation of Japan.

[0052] The performance of the coatings prepared in Comparative Examples 1 to 4 was tested, and the test results are shown in Table 4.

[0053] Table 4 As can be seen from Comparative Examples 1 to 3, compared with Example 1, both surface drying and actual drying are slower. This is because alcohol ester twelve, DB, and DPNB are all high-boiling-point solvents and evaporate slowly. In terms of the appearance, mechanical properties, and durability of the paint film, there is basically no difference from Example 1. The formulation of Example 1 achieved zero VOC.

[0054] In Comparative Example 4, the polyurethane dispersion and the low-hydroxy acrylate dispersion were Wanhua's T6526 and Shiquanxing's 2218, respectively, and the curing agent was Asahi Kasei Corporation's solvent-based curing agent TPA100; while in this application, the polyurethane dispersion and the low-hydroxy acrylate dispersion were Huaguoshan Houxian® 5757 and Houxian® 2046, respectively, and the curing agent was Wanhua's water-based curing agent Aquolin 269A.

[0055] As can be seen from Table 4, the elongation at break of the coating prepared in Comparative Example 4 is 10.2%, which does not meet the standard of elongation greater than 30%. On the contrary, the elongation at break of Example 1 of this application is 41%, which is much greater than the elongation at break of the coating prepared in Comparative Example 4.

[0056] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A water-based zero-VOC coating, characterized in that, The raw materials of the water-based zero-VOC coating consist of component A and component B, wherein the mass ratio of component A to component B is 11:1-12:1; wherein: Component A, by weight, comprises 27-35 parts of low-hydroxyl acrylate dispersion, 27-35 parts of polyurethane dispersion, 1-2 parts of wetting and dispersing agent, 0.1-0.3 parts of defoamer, 17-27 parts of pigments and fillers, 0.05-0.2 parts of color paste, 1-4 parts of matting agent, 0.3-1 parts of substrate wetting agent, 0.3-1 parts of ultraviolet absorber, 0.3-1 parts of light stabilizer, 0.1-0.4 parts of thickener, and 3-12 parts of deionized water; Component B is an aqueous hexamethylene diisocyanate curing agent.

2. The water-based zero-VOC coating according to claim 1, wherein, The low-hydroxyl acrylate dispersion has a solid content of 38-42 wt% and a hydroxyl content of 1.5%-1.8%; and / or, The polyurethane dispersion has a solid content of 50-54 wt% and a hydroxyl value of 62.

7.

3. The water-based zero-VOC coating according to claim 1, wherein, The low-hydroxy acrylate dispersion is a self-crosslinking hydroxy acrylate dispersion; and / or, The polyurethane dispersion is a polycarbonate-type polyurethane dispersion.

4. The water-based zero-VOC coating according to claim 3, wherein, The polyurethane dispersion is an aliphatic hydroxyl-functionalized polycarbonate type polyurethane dispersion.

5. The water-based zero-VOC coating according to any one of claims 1-4, wherein, The wetting and dispersing agent is an aqueous dispersant; The defoamer is one or more of mineral oils, organosilicon compounds, and polyethers; The pigment and filler are titanium dioxide; The matting agent is a water-based matting powder; The substrate wetting agent is an aqueous substrate wetting agent; The ultraviolet absorber is a benzotriazole ultraviolet absorber; The light stabilizer is a hindered amine light stabilizer; The thickener is a nonionic associative thickener.

6. The water-based zero-VOC coating according to any one of claims 1-4, wherein, The pigment and filler are rutile titanium dioxide; The titanium dioxide is a highly weather-resistant rutile titanium dioxide; The substrate wetting agent is an organosilicon twin structure surfactant.

7. A method for preparing a water-based zero-VOC coating according to any one of claims 1-6, characterized in that, The method includes the following steps: 1) Preparation of component A: a. According to the raw material ratio, add wetting and dispersing agent, defoamer, pigments and fillers to deionized water under stirring, mix and grind to obtain pigment slurry for later use; b. According to the raw material ratio, the polyurethane dispersion, low hydroxyl acrylate dispersion, pigment paste, substrate wetting agent, matting agent, ultraviolet absorber, light stabilizer, color paste and thickener are mixed and stirred evenly, and then filtered to obtain component A. 2) Preparation of component B: The cured agent, when filtered, becomes component B; 3) Mix component A and component B according to the mass ratio and stir until homogeneous to obtain the water-based zero-VOC coating.

8. The method according to claim 7, wherein, The preparation of component A includes: a. According to the raw material ratio, add deionized water to the first container, and add the wetting and dispersing agent and the defoamer while stirring. After stirring evenly, add the pigments and fillers and continue stirring evenly. Then grind to obtain the pigment and filler slurry for later use. The fineness of the pigment and filler slurry is ≤20μm. b. According to the raw material ratio, add the polyurethane dispersion and the low-hydroxy acrylate dispersion to the second container, mix and stir evenly; then add the pigment paste, the substrate wetting agent, the matting agent, the ultraviolet absorber, the light stabilizer, the color paste and the thickener while stirring, stir evenly, filter and package to obtain component A.

9. The application of the waterborne zero-VOC coating according to any one of claims 1-6 or the waterborne zero-VOC coating prepared according to the method of claim 7 or 8 in high-toughness, high-weather-resistant products, characterized in that, The product is a wind turbine blade or casing; the water-based zero-VOC coating is used as a primer or topcoat.

10. A coating formed from a waterborne zero-VOC coating according to any one of claims 1-6 or a waterborne zero-VOC coating prepared according to the method of claim 7 or 8, characterized in that, The coating is formed by applying the water-based zero-VOC coating to the substrate and then curing it. The substrate is a wind turbine blade or casing.

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