A wind turbine blade surface protective coating and a method for preparing the same

Abstract

The present application relates to the technical field of paint, in particular to a wind turbine blade surface protective paint and a preparation method thereof. The protective paint comprises component A, component B and component C; the raw material components of component A include polyaspartic ester resin, active diluent, stabilizer, coloring pigment, filler and additive; component B is a polyisocyanate curing agent; and component C is a hydroxyl-terminated polyethylene glycol. The surface protective paint provided by the present application plays a role in protecting the blade substrate, and has the characteristics of fast drying speed, high adhesion to the surface of glass fiber and carbon fiber reinforced composite material, good mechanical properties of the coating, good wear resistance, good weather resistance, and the like. Compared with ordinary polyurea gel coats using polyaspartic ester resin, the surface dry time after painting is greatly shortened, and the overall construction efficiency of blade painting is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a protective coating for the surface of wind turbine blades and its preparation method. Background Technology

[0002] As my country accelerates the implementation of carbon emission reduction measures, wind power, as one of the main clean energy sources, has experienced rapid development.

[0003] Wind turbines typically operate in locations with abundant wind resources, such as oceans, deserts, or high-altitude mountainous areas. These environments are usually extremely harsh; for example, oceans experience high winds and waves with frequent rainfall, while deserts are prone to sandstorms year-round. Furthermore, although the rated rotational speed of the wind turbine blades is not high, the tip linear velocity is very fast, sometimes exceeding 100 m / s. Operating in this environment around the clock, the blades run for an average of approximately 7000 hours per year, subjected to severe damage and erosion from sunlight, dust storms, heavy rain, and snow. The main body of the wind turbine blades is made of glass fiber and carbon fiber reinforced composite materials, which cannot withstand the damage and erosion caused by harsh natural environments and blade movement for extended periods. Therefore, high-performance protective coatings are needed to extend the maintenance cycle of the wind turbine blades and improve investment efficiency.

[0004] Currently, the gel coats used on wind turbine blades are mainly of two types: polyurethane and polyurea. Due to increasingly stringent environmental protection regulations, most are solvent-free or high-solids coatings. Chinese invention patent CN102585684A reports a polyurethane gel coat composition for conventionally sprayable wind turbine blades and its preparation method. It mainly uses a blend of low-viscosity, solvent-free, branched polyester polyol with an average functionality of 3 and a branched polyester polyol with an average functionality of 2.6. An aliphatic isocyanate trimer is used as a curing agent, dibutyltin dilaurate as a drying agent, and diethyl malonate as a retarder. The prepared polyurethane gel coat does not contain organic solvents and can be applied by spraying.

[0005] Polyaspartic acid ester resin possesses excellent mechanical properties and fast drying speed, and has been applied as a coating for wind turbine blades. Chinese invention patent application No. 102391771A reports the development of a wind turbine blade coating using polyaspartic acid ester resin and elastic resin-modified aliphatic isocyanate as the base material. This coating exhibits fast drying speed, a single-layer film thickness of up to 300 μm, high tensile strength and elongation at break, and outstanding wear and impact resistance. However, this coating is a solvent-based coating, containing a certain amount of volatile organic solvents.

[0006] Chinese invention patent CN106243981A discloses a coating for wind turbine blades with high resistance to wind and sand erosion. It achieves good elasticity through a compounding of polyaspartic resin and polyurethane resin. The polyurethane resin used contains two primary amine groups or two primary hydroxyl groups, providing good wear resistance and elasticity after curing. The polyurethane resin and solvent system together extend the pot life of the system. This coating is a solvent-based coating, containing a certain amount of volatile organic solvents.

[0007] Chinese invention patent CN106047112A reports an in-mold gel coat for wind turbine blades, which uses non-polyetheramine diamine compounds and polyetheramine diamine compounds as resins. It features short curing time and good weather resistance, and can directly replace blade coatings.

[0008] Although polyurea gelcoat based on polyaspartic acid ester resin is the most widely used, it also has inherent drawbacks: in inland provinces, winter temperatures are typically low and humidity is low. Factory indoor temperatures are approximately 10-15℃, and humidity is approximately 10-30%. Under these conditions, the surface drying time of polyurea gelcoat based on polyaspartic acid ester resin often extends from 1-2 hours in summer to 5-8 hours, delaying the subsequent processes of repairing pinholes with putty and sanding, thus severely impacting the overall construction efficiency of blade coating. None of the aforementioned patents address how to improve the drying speed of polyurea gelcoat in low-temperature, low-humidity winter environments. Summary of the Invention

[0009] To address the problems of existing technologies, specifically the slow drying speed of polyurea gel coats based on polyaspartic acid ester resin during winter in northern inland regions under low temperature and low humidity conditions, this invention provides a protective coating for the surface of wind turbine blades. The technical solution is as follows:

[0010] The protective coating for the surface of the wind turbine blade comprises component A, component B, and component C; the raw material components of component A include polyaspartic acid ester resin, reactive diluent, stabilizer, coloring pigment, filler, and additives; component B is a polyisocyanate curing agent; and component C is a reactive catalyst; wherein the reactive catalyst is hydroxyl-terminated polyethylene glycol.

[0011] In some embodiments, the additives include wetting and dispersing agents, defoamers, leveling agents, thixotropic agents, and dehydrating agents; by weight, component A includes 60-70 parts of polyaspartic ester resin, 1-9 parts of reactive diluent, 1-3 parts of stabilizer, 0.2-1 parts of wetting and dispersing agent, 0.5-2 parts of defoamer, 0.4-1 parts of leveling agent, 0.1-0.8 parts of thixotropic agent, 3-8 parts of dehydrating agent, 10-15 parts of coloring pigment, and 5-15 parts of filler.

[0012] In some embodiments, the mass ratio of component A, component B and component C is (100-105):(40-50):(2-6).

[0013] In some embodiments, the polyaspartic ester resin is a low-viscosity solvent-free polyaspartic ester resin with a secondary amino group, having a viscosity ≤400 cP and an NH (secondary amino) equivalent of 100–400 g / mol; the reactive diluent is 2-isopropyl-3-oxazolidineethanol; and the stabilizer is tetraisopropyldiphenylcarbodiimide.

[0014] In some embodiments, the reactive catalyst is low-viscosity, solvent-free, hydroxyl-terminated polyethylene glycol with a viscosity ≤50 cP and a hydroxyl equivalent of 50–200 g / mol; the polyisocyanate curing agent is one or more combinations of hexamethylene diisocyanate trimer, isophorone diisocyanate trimer, and dicyclohexylmethane diisocyanate trimer, all of which are free of organic solvents.

[0015] In some embodiments, the coloring pigment is one or more combinations of iron oxide red, iron oxide black, iron oxide yellow, and titanium dioxide; the filler is one or more combinations of wollastonite powder and quartz powder.

[0016] In some embodiments, the dehydrating agent is a molecular sieve dehydrating agent.

[0017] In some embodiments, the molecular sieve dehydrating agent is one or more combinations of potassium molecular sieve, sodium molecular sieve, and calcium molecular sieve, preferably a molecular sieve with a pore size of 0.3 nm and a powder fineness of not less than 325 mesh.

[0018] In some embodiments, the defoamer is one or a combination of two of defoamer Afcona 2722, defoamer 6800, and defoamer GA1890; the leveling agent is one or a combination of two of Eucalyptus leveling agent 384S and Eucalyptus leveling agent 493U; and the thixotropic agent is one or a combination of polyamide wax LV, polyamide wax Ultra, and liquid rheology modifier BYK410.

[0019] This invention also provides a method for preparing the protective coating on the surface of wind turbine blades as described above, wherein the preparation method of component A is as follows:

[0020] First, mix the polyaspartic acid ester resin, reactive diluent, and stabilizer evenly to obtain mixture M;

[0021] Add wetting and dispersing agent, defoamer and dehydrating agent to mixture M, then add filler and coloring pigment under high speed dispersion, grind to fineness less than 40 micrometers by sand milling, and finally add thixotropic agent and leveling agent under high speed dispersion to obtain component A;

[0022] Mix components A, B, and C evenly to obtain the protective coating for the surface of the wind turbine blades.

[0023] Based on the above, compared with the prior art, the wind turbine blade surface protective coating provided by the present invention has the following beneficial effects:

[0024] The protective coating for wind turbine blades provided by this invention serves to protect the blade substrate. This protective coating can be applied in inland winter environments with low temperatures and low humidity. It features fast drying speed, high adhesion to glass fiber and carbon fiber reinforced composite materials, and good mechanical properties, wear resistance, and weather resistance. Compared with ordinary polyurea gel coats using polyaspartic acid ester resin, the surface drying time after coating is greatly shortened, significantly improving the overall construction efficiency of blade coating.

[0025] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures and / or components pointed out in the description and claims. Detailed Implementation

[0026] To make the objectives, 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. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0028] This invention provides a method for preparing a protective coating for the surface of wind turbine blades, comprising the following steps:

[0029] The preparation method of component A is as follows:

[0030] (1) First, mix the polyaspartic acid ester resin, reactive diluent, and stabilizer evenly to obtain mixture M;

[0031] (2) Add wetting and dispersing agent, defoamer and dehydrating agent to mixture M, then add filler and coloring pigment under high speed dispersion, grind with sand mill to fineness less than 40 micrometers, and finally add thixotropic agent and leveling agent under high speed dispersion to obtain component A;

[0032] When using, mix components A and B thoroughly, then add component C and mix thoroughly to obtain the protective coating, which can then be applied.

[0033] The formulations of components A and B are as follows:

[0034] By weight, component A comprises 60-70 parts of polyaspartic ester resin, 1-9 parts of reactive diluent, 1-3 parts of stabilizer, 0.2-1 parts of wetting and dispersing agent, 0.5-2 parts of defoamer, 0.4-1 parts of leveling agent, 0.1-0.8 parts of thixotropic agent, 3-8 parts of dehydrating agent, 10-15 parts of coloring pigment, and 5-15 parts of filler. The mass ratio of component A, component B, and component C is (100-105):(40-50):(2-6).

[0035] The selected raw materials are:

[0036] The polyaspartic acid ester resin is a low-viscosity, solvent-free polyaspartic acid ester resin with a viscosity ≤400 cP and an NH equivalent of 100–400 g / mol. The reactive diluent is 2-isopropyl-3-oxazolidineethanol. The stabilizer is tetraisopropyldiphenylcarbodiimide. The dehydrating agent is a molecular sieve dehydrating agent, which may be selected from one or more combinations of potassium-type molecular sieves, sodium-type molecular sieves, and calcium-type molecular sieves. The coloring pigment is selected from one or more combinations of iron oxide red, iron oxide black, iron oxide yellow, and titanium dioxide. The filler is selected from one or more combinations of wollastonite powder and quartz powder.

[0037] The B component is a polyisocyanate curing agent; specifically, the polyisocyanate curing agent is one or more combinations of hexamethylene diisocyanate trimer without organic solvent, isophorone diisocyanate trimer without organic solvent, and dicyclohexylmethane diisocyanate trimer without organic solvent.

[0038] The C component is a reactive catalyst; wherein the reactive catalyst is hydroxyl-terminated polyethylene glycol, specifically a low-viscosity, solvent-free hydroxyl-terminated polyethylene glycol with a viscosity ≤50 cP and a hydroxyl equivalent of 50–200 g / mol.

[0039] The present invention also provides the following embodiments and comparative examples of formulations (unit: parts by weight), as shown in Tables 1-2 below:

[0040] Table 1

[0041]

[0042]

[0043] In Table 1, the specific selection of each raw material component in the above embodiments and comparative examples is as follows:

[0044] The selected polyaspartic acid ester resin is a low-viscosity solvent-free polyaspartic acid ester resin with a viscosity of 140 cP and an NH equivalent of 290 (except for Comparative Example 6).

[0045] The selected reactive diluent is 2-isopropyl-3-oxazolidineethanol;

[0046] The stabilizer selected is tetraisopropyldiphenylcarbodiimide.

[0047] The defoamer is Afcona 2722 and defoamer 6800, with a mass ratio of 2:1.

[0048] The leveling agent used is 384S;

[0049] The selected thixotropic agent is the liquid rheology modulator BYK410;

[0050] The selected molecular sieve dehydrating agent is 1503L;

[0051] The selected coloring pigment is titanium dioxide;

[0052] The fillers selected are wollastonite and quartz powder, with a mass ratio of 1:3.

[0053] The selected polyisocyanate curing agent is hexamethylene diisocyanate trimer without organic solvents;

[0054] The selected reactive catalyst is low-viscosity, solvent-free, hydroxyl-terminated polyethylene glycol with a viscosity of 25 cP and a hydroxyl equivalent of 100.

[0055] According to the formulations in Table 1-2, the above examples and comparative examples were prepared using the following methods to obtain component A:

[0056] The preparation method of component A is as follows:

[0057] (1) First, mix the polyaspartic acid ester resin, reactive diluent, and stabilizer evenly to obtain mixture M;

[0058] (2) Add wetting and dispersing agent, defoamer and dehydrating agent to mixture M, then add filler and coloring pigment under high speed dispersion, grind with sand mill to fineness less than 40 micrometers, and finally add thixotropic agent and leveling agent under high speed dispersion to obtain component A;

[0059] When using, mix components A and B thoroughly, then add component C and mix thoroughly to obtain the protective coating, which can then be applied.

[0060] The products obtained in the above embodiments and the products obtained in the comparative examples, after being mixed and used with components A, B, and C, underwent the following performance tests, and the test results are shown in Table 2 below:

[0061] Table 2 Performance Test Data

[0062]

[0063]

[0064] Note: In the table above, the surface drying time, actual drying time, and pot life were tested at an ambient temperature of 12.5℃ and a humidity of 20%. The pot life record node is the time it takes for the viscosity of the coating to increase to greater than 3000 cP after mixing.

[0065] The main performance indicators and testing methods of the protective coating for wind turbine blades provided by this invention are shown in Table 3 below:

[0066] Table 3

[0067]

[0068]

[0069] Analysis of the data results from the examples and comparative examples shows that:

[0070] The protective coating for wind turbine blades provided in this invention serves to protect the blade substrate. This protective coating can be applied in inland winter environments with low temperatures and low humidity. It features fast drying speed, high adhesion to glass fiber and carbon fiber reinforced composite materials, and good mechanical properties, wear resistance, and weather resistance. Compared with ordinary polyurea gel coats using polyaspartic acid ester resin, the surface drying time after coating is shortened from 5-8 hours to 2-4 hours, greatly reducing the overall construction efficiency of blade coating.

[0071] The only difference between Comparative Example 1 and Example 3 is that Comparative Example 1 did not contain hydroxyl-terminated polyethylene glycol; compared to the Example 3, when applied in a low temperature and low humidity environment, its drying speed was significantly reduced, and its adhesion and tensile strength were slightly decreased.

[0072] The only difference between Comparative Example 2 and Example 3 is that hydroxyl acrylic resin is used instead of hydroxyl-terminated polyethylene glycol. Compared with the Example, when applied in a low temperature and low humidity environment, the drying speed is significantly reduced, and its adhesion, tensile strength and abrasion resistance are slightly reduced.

[0073] The only difference between Comparative Example 3 and Example 3 is that the proportion of hydroxyl-terminated polyethylene glycol added is lower than that specified in this application; compared with the Example, when applied in an environment with low temperature and low humidity, the drying speed is significantly reduced, and the adhesion and tensile strength are slightly reduced.

[0074] The only difference between Comparative Example 4 and Example 3 is that the proportion of terminal hydroxyl polyethylene glycol added is higher than that specified in this application; compared with the Example, its adhesion is reduced and its pot life is significantly reduced to only 20 minutes.

[0075] The only difference between Comparative Example 5 and Example 3 is that the solvent-free polyaspartic acid ester resin used in Comparative Example 5 has a higher viscosity and a lower secondary amino equivalent; compared with the Example 3, its wear resistance and service life are significantly reduced.

[0076] The technical solution for the protective coating on the surface of wind turbine blades provided by this invention includes at least the following design concepts and beneficial effects:

[0077] 1. Design Concept

[0078] The surface protective coating provided by this invention uses low-viscosity polyaspartic acid ester resin as the main resin and aliphatic polyisocyanate as the curing agent. Low-viscosity, solvent-free hydroxyl-terminated polyethylene glycol (PEG) is used as the reactive catalyst component. The viscosity of the hydroxyl-terminated PEG is ≤50 cP, and the hydroxyl equivalent is 50-200 g / mol. The hydroxyl groups of the PEG catalyze the reaction between polyaspartic acid ester and polyisocyanate at low temperature and low humidity, accelerating the drying speed of the gel coat. Simultaneously, the hydroxyl groups of the PEG can also react with the polyisocyanate for curing without affecting the mechanical properties of the gel coat. The resulting winter-grade polyurea gel coat, applied in inland winter environments with low temperatures and low humidity, features fast drying speed, good adhesion to the blade surface, and good mechanical properties. Furthermore, the amount of the reactive catalyst component can be adjusted according to the ambient temperature and humidity, enabling application under different temperature and humidity conditions, demonstrating good adaptability to various application environments. Within the scope of this application, the lower the ambient temperature and humidity, the more reactive catalyst can be added to suit the environment, while maintaining good mechanical properties of the coating.

[0079] In summary, the surface protective coating of this invention uses low-viscosity polyaspartic acid ester resin as the main resin and aliphatic polyisocyanate as the curing agent; it also uses low-viscosity solvent-free hydroxyl-terminated polyethylene glycol as the reactive catalyst component. The hydroxyl groups of the hydroxyl-terminated polyethylene glycol catalyze the reaction between polyaspartic acid ester and polyisocyanate at low temperature and low humidity, thus accelerating the drying speed of the gel coat. Simultaneously, the hydroxyl groups of the hydroxyl-terminated polyethylene glycol can also react with the polyisocyanate for curing without affecting the mechanical properties of the gel coat.

[0080] 2. Beneficial effects

[0081] The protective coating for wind turbine blades provided by this invention serves to protect the blade substrate. The main material of wind turbine blades is a composite material reinforced with glass fiber and carbon fiber. To improve the blades' resistance to natural environments, their surfaces are typically coated with a protective coating consisting of gel coat and topcoat. This invention is a polyurea gel coat applied to the surface of wind turbine blades. This coating exhibits characteristics such as rapid drying speed, high adhesion to the surface of glass fiber and carbon fiber reinforced composite materials, good toughness, good wear resistance, and good weather resistance, even in the low-temperature and low-humidity winter environments of northern inland areas. Compared with ordinary polyurea gel coats using polyaspartic acid ester resin, the surface drying time after coating is shortened from 5-8 hours to 2-4 hours, greatly improving the overall construction efficiency of blade coating and resulting in significant economic and social benefits.

[0082] In addition, the coating of this invention is packaged in three components, and the amount of catalyst component can be adjusted according to the temperature and humidity of the construction environment, which has good adaptability to the construction environment.

[0083] It should be noted that:

[0084] In this article, “~” is used to represent the range of values, and the range of values ​​represented by this expression includes two endpoint values.

[0085] The specific parameters or commonly used reagents in the above embodiments are specific or preferred embodiments under the concept of this invention, and are not intended to limit it; those skilled in the art can make adaptive adjustments within the concept and protection scope of this invention. Furthermore, unless otherwise specified, the raw materials used can also be commercially available products in the art, or prepared by conventional methods in the art.

[0086] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0087] Although terms such as filler and polyaspartic acid ester resin are frequently used in this document, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention. The terms "first," "second," etc. (if present) in the description and claims of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A protective coating for the surface of wind turbine blades, characterized in that: It includes component A, component B, and component C; The raw material components of component A include polyaspartic acid ester resin, reactive diluent, stabilizer, coloring pigment, filler and additives; Component B is a polyisocyanate curing agent; Component C is a reactive catalyst; wherein, the reactive catalyst is hydroxyl-terminated polyethylene glycol; The additives include wetting and dispersing agents, defoamers, leveling agents, thixotropic agents, and dehydrating agents; By weight, component A comprises 60-70 parts of polyaspartic acid ester resin, 1-9 parts of reactive diluent, 1-3 parts of stabilizer, 0.2-1 parts of wetting and dispersing agent, 0.5-2 parts of defoamer, 0.4-1 parts of leveling agent, 0.1-0.8 parts of thixotropic agent, 3-8 parts of dehydrating agent, 10-15 parts of coloring pigment, and 5-15 parts of filler; The mass ratio of component A, component B and component C is (100-105):(40-50):(2-6). The reactive catalyst is a low-viscosity, solvent-free, hydroxyl-terminated polyethylene glycol with a viscosity ≤50 cP and a hydroxyl equivalent of 50–200 g / mol. The polyaspartic acid ester resin is a low-viscosity solvent-free polyaspartic acid ester resin with secondary amino groups, and its viscosity is ≤400 cP and NH equivalent is 100~400 g / mol. The active diluent is 2-isopropyl-3-oxazolidineethanol; The stabilizer is tetraisopropyldiphenylcarbodiimide.

2. The protective coating for wind turbine blades according to claim 1, characterized in that: The polyisocyanate curing agent is one or more combinations of hexamethylene diisocyanate trimer without organic solvent, isophorone diisocyanate trimer without organic solvent, and dicyclohexylmethane diisocyanate trimer without organic solvent.

3. The protective coating for wind turbine blades according to claim 1, characterized in that: The coloring pigment is one or more of iron oxide red, iron oxide black, iron oxide yellow, and titanium dioxide; The filler is one or more of wollastonite powder and quartz powder.

4. The protective coating for wind turbine blades according to claim 1, characterized in that: The dehydrating agent is a molecular sieve dehydrating agent.

5. The protective coating for wind turbine blades according to claim 4, characterized in that: The molecular sieve dehydrating agent is one or more of potassium molecular sieves, sodium molecular sieves, and calcium molecular sieves.

6. The protective coating for wind turbine blades according to claim 1, characterized in that: The defoamer is one or a combination of two of the following: defoamer Afcona 2722, defoamer 6800, and defoamer GA1890; The leveling agent is one or a combination of two of Eucalyptus leveling agent 384S and Eucalyptus leveling agent 493U. The thixotropic agent is one or a combination of polyamide wax LV, polyamide wax Ultra, and liquid rheology modifier BYK410.

7. A method for preparing a protective coating for the surface of a wind turbine blade as described in claim 1, characterized in that: The preparation method of component A is as follows: First, mix the polyaspartic acid ester resin, reactive diluent, and stabilizer evenly to obtain mixture M; Add wetting and dispersing agent, defoamer and dehydrating agent to mixture M, then add filler and coloring pigment under high speed dispersion, grind to fineness less than 40 micrometers by sand milling, and finally add thixotropic agent and leveling agent under high speed dispersion to obtain component A; Mix components A, B, and C evenly to obtain the protective coating for the surface of the wind turbine blades.

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