Environment-friendly coating and spraying method thereof

Abstract

The invention discloses an environment-friendly coating and a spraying method thereof.The environment-friendly coating is prepared from, by weight, bio-based resin and filler, the filler comprises organic filler and inorganic filler, the mass ratio of the organic filler to the inorganic filler is 9: 1-1: 9, the melt level fluidity of the environment-friendly coating can be improved, and the environment-friendly coating can easily form a film; and the comprehensive properties such as appearance, gloss, impact strength and pencil hardness of the coating are excellent. The filler is a composite filler formed by matching biomass lignin, cellulose and an inorganic filler, so that the mechanical strength, the processability, the surface tension and the permeability of a coating film can be improved, the adhesive force of the coating can be improved, the dispersion of other fillers in the coating can be assisted, and the stability of a medium can be protected; meanwhile, by using the filler disclosed by the invention, the resin consumption can be reduced, the production cost is reduced, cracks are prevented, ultraviolet rays and moisture are prevented from permeating, and the service life of a paint film is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to an environmentally friendly coating and a spraying method thereof. Background Art

[0002] Powder coating refers to 100% solid powder coating without solvent. It exists in the form of fine powder and has the characteristics of being solvent-free, pollution-free, recyclable, environmentally friendly, energy and resource-saving, labor-reducing and high mechanical strength of the coating film. Powder coating has a large production and sales volume and a wide range of applications. It is widely used in surface coatings of household appliances, high-voltage motors, electronic devices, lighting fixtures, furniture, etc.

[0003] At present, powder coatings generally have the following defects and deficiencies: long curing time, poor adhesion to the substrate after film formation, and large volume shrinkage. Especially when applied to the surface of various metal objects, the coating is required to have good protective and decorative properties. Since the thermal conductivity of metal objects is often high, the coating is prone to blistering and falling off after heating, cracks are prone to appear on the coating surface, and ultraviolet rays and moisture can easily penetrate the coating, resulting in a short service life of the coating. The comprehensive properties of the coating, such as appearance, gloss, impact strength and pencil hardness, are difficult to meet the use requirements. Summary of the invention

[0004] In view of the problems pointed out in the background technology, the purpose of the present invention is to provide an environmentally friendly coating and a spraying method thereof.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: The present invention provides an environmentally friendly coating, which is made of the following raw materials in parts by weight: a bio-based resin, whose parts by weight are greater than or equal to 20 parts and whose parts by weight are less than or equal to 70 parts; a filler, whose parts by weight are greater than or equal to 10 parts and whose parts by weight are less than or equal to 40 parts; the filler comprises an organic filler and an inorganic filler, and the mass ratio of the organic filler to the inorganic filler is greater than or equal to 1 / 9, and the mass ratio of the organic filler to the inorganic filler is less than or equal to 9; the organic filler comprises at least one of lignin-based carbon fiber, microcrystalline cellulose and a cellulose derivative.

[0006] In some embodiments of the present application, the bio-based resin is prepared from biomaterials, and the biomaterials include bio-based epoxy resins based on plant phenols, and derivatives based on cellulose, starch, and chitin.

[0007] In some embodiments of the present application, the bio-based epoxy resin includes a monophenolic epoxy resin and / or a polyphenolic epoxy resin.

[0008] In some embodiments of the present application, the derivatives based on cellulose, starch and chitosan include cellulose aliphatic polyester and / or chitosan aliphatic polyester.

[0009] In some embodiments of the present application, the inorganic filler includes titanium dioxide, silicon powder and / or barium sulfate.

[0010] In some embodiments of the present application, the environmentally friendly coating includes a leveling agent, the weight of which is Greater than or equal to 0.1 parts, and less than or equal to 3 parts by weight.

[0011] In some embodiments of the present application, the leveling agent includes an acrylic leveling agent and / or a polyether leveling agent.

[0012] In some embodiments of the present application, the environmentally friendly coating includes a curing agent, the weight parts of which are Greater than or equal to 0.5 parts, and less than or equal to 15 parts by weight.

[0013] In some embodiments of the present application, the curing agent includes aliphatic amines, aromatic amines, polyamines and / or acid anhydrides.

[0014] The present application also provides a method for spraying the environmentally friendly coating, which comprises: (1) Pre-treat the substrate to be sprayed, and remove pollutants such as oil, slight oxidation and dust from the substrate through a spray system; spray the passivation liquid on the cleaned substrate surface to form a passivation film on the substrate surface; (2) Drying the substrate so that the substrate is preheated to 100°C-220°C; (3) spraying the environmentally friendly coating onto the passivation film of the substrate using an electrostatic spraying process to obtain a powder coating; (4) The substrate with the powder coating in step (3) is placed in a drying furnace at 100-220°C. The coating is melted, solidified and leveled after high-temperature baking to obtain a substrate with a powder coating on the surface.

[0015] In some embodiments of the present application, the step (1), the passivation solution includes chromium Passivation liquid and / or non-cyanide complexing agent; in the step (3), the voltage of electrostatic spraying is greater than or equal to 20KV, and the voltage is less than or equal to 100 KV; the current is greater than or equal to 3uA, and the current is less than or equal to 95uA; the powder output is greater than or equal to 15g / min, and the powder output is less than or equal to 95g / min.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are: the present invention provides an environmentally friendly coating and a spraying method thereof, the environmentally friendly coating comprising the following raw materials in parts by weight: a bio-based resin, wherein the weight portion is greater than or equal to 20 parts and the weight portion is less than or equal to 70 parts; a filler, wherein the weight portion is greater than or equal to 10 parts and the weight portion is less than or equal to 40 parts; the filler comprises an organic filler and an inorganic filler, and the mass ratio of the organic filler to the inorganic filler is 1:9-9:1; the organic filler comprises at least one of lignin-based carbon fiber, microcrystalline cellulose and a cellulose derivative.

[0017] Compared with traditional coating materials, the coating prepared from bio-based resin in the present invention can reduce pollution to the environment and potential harm to health, reduce carbon emissions, and is conducive to the realization of carbon neutrality goals.

[0018] The fillers include organic fillers and inorganic fillers, and the mass ratio of the organic fillers to the inorganic fillers is 9:1-1:9; the filler ratio within this range can improve the melt level fluidity of the environmentally friendly coating, making the environmentally friendly coating easy to form a film; in addition, it can also make the coating have excellent comprehensive properties such as appearance, gloss, impact strength and pencil hardness.

[0019] The filler of the present invention is a composite filler composed of biomass lignin, cellulose and inorganic fillers, which can not only improve the mechanical strength, processing performance, surface tension and permeability of the coating film, so that it can better adhere to the surface of the substrate, thereby improving the adhesion of the coating, but also assist other fillers in dispersing in the coating and play a protective role in the stability of the medium; at the same time, the use of the filler of the present invention can reduce the amount of resin used, reduce production costs, prevent cracks, prevent ultraviolet rays and moisture from penetrating, and extend the service life of the paint film.

[0020] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the preparation process of the environmentally friendly coating of the present invention.

[0022] Figure 2 The present invention is a process flow chart of coating electrostatic spraying molding. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0026] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0029] The environmentally friendly coating of the present invention is made of the following raw materials: bio-based resin and filler, the filler includes organic filler and inorganic filler, the organic filler includes biomass filler, for example, the biomass filler can be at least one of lignin-based carbon fiber, microcrystalline cellulose and cellulose derivatives.

[0030] If the bio-based resin content S1 is too small, the film-forming performance of the environmentally friendly coating is poor, and it is not easy to form a uniform and stable film. At the same time, if the bio-based resin content S1 is too small, the structure and performance of the bio-based resin are not easy to appear in the system, and the mechanical properties of the environmentally friendly coating cannot be guaranteed. Therefore, the content S1 of the bio-based resin is greater than or equal to the first parameter value. For example, the first parameter value can be 20 parts. When considering the selection of a suitable specific parameter in the specific design, no specific restrictions are made here.

[0031] If the bio-based resin content S1 is too large, the curing time of the coating will be longer, the curing effect will be worse, and the mechanical properties will be reduced. At the same time, if the bio-based resin content S1 is too large, the cost will increase. Therefore, the bio-based resin content S1 is less than or equal to the second parameter value. For example, the second parameter value can be 70 parts. When designing specifically, consider selecting a suitable specific parameter, and no specific restrictions are made here.

[0032] Therefore, the present invention can optimize the bio-based resin content S1 so that the bio-based resin content S1 can be greater than or equal to 20 parts, and S1 can be less than or equal to 70 parts.

[0033] Preferably, the bio-based resin content S1 can be greater than or equal to 20 parts, and S1 can be less than or equal to 35 parts; within this range, the environmentally friendly coating can have good processing performance and strong adhesion, and at the same time can accelerate the curing rate of the environmentally friendly coating, which is conducive to the rapid film formation of the environmentally friendly coating.

[0034] Alternatively, the bio-based resin content S1 can be greater than or equal to 35 parts, and S1 can be less than or equal to 50 parts; within this range, the coating can have good film-forming properties, excellent coating properties, and good coating dispersibility and leveling properties.

[0035] Alternatively, the bio-based resin content S1 can be greater than or equal to 50 parts, and S1 can be less than or equal to 70 parts; within this range, the environmentally friendly coating has good toughness, stable performance, and excellent corrosion resistance, wear resistance, impact resistance and tear resistance.

[0036] The bio-based resin is prepared by a derivatization reaction of biomaterials, wherein the biomaterials include cellulose, lignin, starch and / or chitin. For example, the biomaterials include bio-based epoxy resins based on plant phenols, and derivatives based on cellulose, starch and chitin.

[0037] Biomaterials use renewable substances as raw materials, are abundant in source and are renewable resources. At the same time, cellulose, lignin, starch and / or chitin can be extracted from non-food straw and shells. They have low preparation costs, are environmentally friendly and degradable, and have excellent performance and controllable structure.

[0038] The raw materials of bio-based resins are widely available and easy to extract. In addition, bio-based resins are natural polymers with strong sustainability, which can minimize the cost of coatings. Compared with traditional coating materials, the coatings prepared from bio-based resins in the present invention can reduce pollution to the environment and potential harm to health, reduce carbon emissions, and are conducive to the realization of carbon neutrality goals.

[0039] Fillers include organic fillers and inorganic fillers. The filler content directly affects the mechanical properties of environmentally friendly coatings. The appropriate addition of fillers will affect the flexibility of the resin, improve the dispersibility and fluidity of environmentally friendly coatings, and improve the mechanical properties of environmentally friendly coatings.

[0040] If the filler content S2 is smaller, the dispersibility and fluidity of the environmentally friendly coating will be worse; therefore, the filler content S2 is greater than or equal to the first parameter value. For example, the first parameter value can be 10 parts. When designing specifically, consider selecting a suitable specific parameter, and no specific limitation is made here.

[0041] If the filler content S2 is larger, the environmentally friendly coating becomes more brittle and more prone to cracking. Therefore, the filler content S2 is made less than or equal to the second parameter value. For example, the second parameter value may be 40 parts. When designing specifically, a suitable specific parameter may be considered and is not specifically limited here.

[0042] The present invention can optimize the filler content S2 so that the filler content S2 is greater than or equal to 10 parts and less than or equal to 40 parts.

[0043] Preferably, the filler content S2 may be greater than or equal to 10 parts, and S2 may be less than or equal to 20 parts; within this range, the flexibility of the resin can be improved, and thus its dispersibility and fluidity can be improved, and the coating can have excellent mechanical properties and be less likely to crack.

[0044] Alternatively, the filler content S2 can be greater than or equal to 20 parts, and S2 can be less than or equal to 30 parts; within this range, the flexibility of the resin can be improved, and then its dispersibility and fluidity can be improved, and the coating can have excellent mechanical properties and is not easy to crack.

[0045] Alternatively, the filler content S2 can be greater than or equal to 30 parts, and S2 can be less than or equal to 40 parts; within this range, the melt level fluidity, coating film appearance, gloss and pencil hardness of the environmentally friendly coating can be effectively improved.

[0046] Different filler types and proportions have significantly different effects on the curing time and melt level fluidity of environmentally friendly coatings; and there are particularly significant differences in their effects on the appearance, gloss, impact strength and pencil hardness of the coating.

[0047] The fillers include organic fillers and inorganic fillers, and the mass ratio of the organic fillers to the inorganic fillers is 9:1-1:9; the filler ratio within this range can improve the melt level fluidity of the environmentally friendly coating, making the environmentally friendly coating easy to form a film; in addition, it can also make the coating have excellent comprehensive properties such as appearance, gloss, impact strength and pencil hardness.

[0048] The organic filler includes biomass lignin, for example, it can be at least one of lignin-based carbon fiber, microcrystalline cellulose and cellulose derivatives. Lignin and cellulose are abundant and advanced carbon-based structural or functional material matrices in nature. Due to the complexity and diversity of their functional groups, they have good mechanical properties, physical and chemical properties, biodegradability and antioxidant properties, as well as excellent thermal stability.

[0049] The inorganic filler may include titanium dioxide, silica powder and / or barium sulfate.

[0050] The filler of the present invention is a composite filler composed of biomass lignin, cellulose and inorganic fillers, which can not only improve the mechanical strength, processing performance, surface tension and permeability of the coating film, so that it can better adhere to the surface of the substrate, thereby improving the adhesion of the coating, but also assist other fillers in dispersing in the coating and play a protective role in the stability of the medium; at the same time, the use of the filler of the present invention can reduce the amount of resin used, reduce production costs, prevent cracks, prevent ultraviolet rays and moisture from penetrating, and extend the service life of the paint film.

[0051] Lignin and cellulose, due to their benzene ring and pentose ring structures, can increase the viscosity of the coating to the required level, improve the fluidity and stability of the coating, improve the compatibility of the coating with other additives, and at the same time give the coating good construction performance and facilitate rapid film formation of the coating. Fillers can also participate in film formation and improve the performance of other additives.

[0052] The environmentally friendly coating of the present invention also includes a leveling agent, and the present invention uses acrylate and polyether leveling agents.

[0053] Leveling agents can help the paint form a flat, smooth and uniform coating during the drying and film-forming process. They mainly reduce the softening point of the system, improve the surface tension between the paint and the substrate, make the paint and the substrate have optimal wettability, promote the fluidity of the paint film, and improve the smoothness, anti-scratch and anti-adhesion properties of the coating.

[0054] If the weight of the leveling agent S3 is too small, it can only slightly reduce the surface tension of the coating, and cannot balance the surface tension difference of the paint film. Therefore, the weight of the leveling agent S3 is greater than or equal to the first parameter value. For example, the first parameter value can be 0.1 parts. When designing specifically, consider selecting a suitable specific parameter, and no specific limitation is made here.

[0055] If the weight of the leveling agent S3 is too large, the content is too much, the coating migrates quickly on the surface of the substrate, the wettability of the substrate is poor, and the system compatibility is poor. Therefore, the weight of the leveling agent S3 is less than or equal to the second parameter value. For example, the second parameter value can be 5 parts. When designing specifically, consider selecting a suitable specific parameter, and no specific limitation is made here.

[0056] The present invention can optimize the weight portion S3 of the leveling agent so that S3 is greater than or equal to 0.1 parts and less than or equal to 5 parts.

[0057] Preferably, the weight portion S3 of the leveling agent can be greater than or equal to 0.1 parts, and S3 can be less than or equal to 2 parts; within this range, the leveling agent can effectively reduce the surface tension between the coating and the substrate, so that the coating and the substrate have optimal wettability, promote the fluidity of the paint film, improve the smoothness, scratch resistance and adhesion resistance of the coating, and can effectively prevent the coating from migrating too fast on the surface of the substrate.

[0058] Alternatively, the weight proportion of the leveling agent S3 may be greater than or equal to 2 parts, and S3 may be less than or equal to 3 parts; within this range, the leveling agent can effectively reduce the surface tension between the coating and the substrate, so that the coating and the substrate have optimal wettability, promote the fluidity of the paint film, improve the smoothness, scratch resistance and adhesion resistance of the coating, and can effectively prevent the coating from migrating too quickly on the surface of the substrate.

[0059] Alternatively, the weight proportion of the leveling agent S3 may be greater than or equal to 3 parts, and S3 may be less than or equal to 5 parts; within this range, the leveling agent can effectively reduce the surface tension between the coating and the substrate, so that the coating and the substrate have optimal wettability, promote the fluidity of the paint film, improve the smoothness, scratch resistance and adhesion resistance of the coating, and can effectively prevent the coating from migrating too quickly on the surface of the substrate.

[0060] The curing agent of the present invention includes aliphatic amines, aromatic amines, polyamines and / or acid anhydrides.

[0061] During the thermal curing reaction, the active groups in the coating react with the curing agent to form a cross-linked structure, thereby allowing the coating to cure.

[0062] Curing agent is an indispensable component of epoxy / polyester powder coating. It chemically reacts with specific functional groups in epoxy resin to cross-link epoxy / polyester resin molecules to form a cross-linked structure, thus giving the coating excellent performance. The content of curing agent directly determines the degree and speed of the reaction, which in turn affects the final performance of the coating.

[0063] 1. As the curing agent content increases, the cross-linking density inside the coating increases, and the hardness of the coating usually increases accordingly, which helps to enhance the chemical corrosion resistance of the coating. Excessive curing agent content may cause other side effects, such as reducing the impact resistance of the coating and making the coating brittle.

[0064] 2. When the curing agent content is moderate, the coating can maintain good flexibility to adapt to the deformation of the substrate. Too high or too low a curing agent content may affect the flexibility of the coating. Too high a curing agent content will make the coating too brittle, while too low a curing agent content may cause the coating to be incompletely cured, affecting the mechanical properties.

[0065] 3. An appropriate amount of curing agent helps to form a dense coating structure and improve the adhesion between the coating and the substrate. Too high or too low a curing agent content may lead to a decrease in coating adhesion.

[0066] 4. The curing agent content will also affect the appearance quality of the coating. An appropriate amount of curing agent can ensure that the coating surface is smooth and has high gloss. However, too low a curing agent content may lead to incomplete curing of the coating, resulting in problems such as rough surface and poor gloss; while too high a curing agent content may cause surface defects of the coating, such as pinholes and bubbles.

[0067] Generally speaking, the curing agent content should be controlled within a certain range to ensure that the coating has optimal hardness, flexibility, adhesion, chemical resistance and appearance quality.

[0068] If the weight of the curing agent S4 is too small, the coating will not be completely cured, affecting the mechanical properties of the coating, and the coating will have problems such as surface roughness and poor gloss. Therefore, the weight of the curing agent S4 is greater than or equal to the first parameter value. For example, the first parameter value can be 0.05 parts. When designing specifically, consider selecting a suitable specific parameter, and no specific limitation is made here.

[0069] If the weight of the curing agent S4 is too large, the impact resistance of the coating will be reduced, making the coating brittle; it may also cause surface defects of the coating, such as pinholes, bubbles, etc. Therefore, the weight of the curing agent S4 is less than or equal to the second parameter value. For example, the second parameter value can be 0.5 parts. When designing specifically, consider selecting a suitable specific parameter, and no specific limitation is made here.

[0070] Preferably, the weight portion S4 of the curing agent can be greater than or equal to 0.05 parts, and S2 can be less than or equal to 0.1 parts; within this range, the coating can have optimal hardness, flexibility, adhesion, chemical resistance and appearance quality.

[0071] Alternatively, the weight portion S4 of the curing agent can be greater than or equal to 0.1 parts, and S2 can be less than or equal to 0.35 parts; within this range, the coating can have optimal hardness, flexibility, adhesion, chemical resistance and appearance quality.

[0072] Alternatively, the weight portion S4 of the curing agent can be greater than or equal to 0.35 parts, and S2 can be less than or equal to 0.5 parts; within this range, it can effectively ensure that the coating has optimal hardness, flexibility, adhesion, chemical resistance and appearance quality.

[0073] The spraying method of the environmentally friendly coating of the present invention comprises: (1) Pretreatment: Spray the substrate surface through a spray system to remove oil, slight oxidation, dust and other pollutants on the substrate surface to provide a good base suitable for spraying; spray the passivation liquid on the cleaned substrate surface to form a uniform passivation film on the substrate surface to enhance the adhesion of the coating to the substrate surface.

[0074] The nozzles of the spray system can be V-shaped, cross-shaped, fan-shaped, spherical, spiral or polygonal, which can achieve fully uniform spraying on the surface of the substrate.

[0075] The passivation solution may include chromium passivation solution and / or non-cyanide complexing agent; the passivation solution of the present application has little harm to human body and environment and meets environmental protection requirements; it has efficient complexing ability, and the film formed by chromium passivation has good heat resistance; the production cost is low; the film layer has bright color, dense structure and strong corrosion resistance.

[0076] (2) Drying: Preheat the substrate to 100°C-220°C to dry the moisture on the surface of the substrate; (3) Electrostatic spraying: The environmentally friendly coating of the present invention is sprayed onto the passivation film of the substrate by an electrostatic spraying process, wherein the particle size of the environmentally friendly coating is 20-80 μm, to obtain a substrate with the coating attached; The particle size of powder coating has a direct impact on its fluidity. Powder with moderate particle size can flow smoothly during spraying, which is conducive to the uniform distribution of coating and can form a flat and smooth coating surface with good aesthetics. However, powder with too large or too small particle size may affect its fluidity, resulting in uneven spraying, uneven and rough coating, etc.

[0077] Powder coatings with moderate particle sizes have a higher powder coating rate, which can ensure the thickness and quality of the coating. However, powder coatings with too small or too large particle sizes may reduce the powder coating rate and affect the coating quality.

[0078] Powder coatings with too small particle size are prone to moisture absorption and agglomeration, which will affect the use effect. Powder coatings with moderate particle size have better stability and are conducive to long-term storage and use. Powder coatings with too large or too small particle size may cause problems such as unevenness and roughness on the coating surface, and will also increase recycling costs.

[0079] The particle size of the environmentally friendly coating of the present application is 20-80 μm. The powder coating within this range has good fluidity and chargeability during electrostatic spraying, which can ensure uniform coating coverage and a high powder coating rate.

[0080] The voltage of electrostatic spraying is greater than or equal to 20KV, and the voltage is less than or equal to 100 KV; the current is greater than or equal to 3uA, and the current is less than or equal to 95uA.

[0081] The powder yield directly affects the curing effect, coating thickness and appearance quality of the coating: if the powder yield is too high or too low, it may affect its fluidity, resulting in uneven spraying, uneven and rough coating, etc.

[0082] A moderate powder yield can make the paint have good fluidity and uniform spraying, which is conducive to the uniform distribution of the paint, and can form a flat and smooth coating surface with good aesthetics, and can ensure the thickness and quality of the coating.

[0083] The powder output of the present application is greater than or equal to 15g / min, and the powder output is less than or equal to 95g / min, which can make the coating have good fluidity and uniform spraying, which is conducive to the uniform distribution of the coating, and can form a flat and smooth coating surface with good aesthetics, and can ensure the thickness and quality of the coating.

[0084] The electrostatic spraying process of the present application can accurately identify the shape and position of the workpiece, and can accurately position the spray gun to the position where spraying is required even if the workpiece is deflected; at the same time, it can automatically sense the sprayed workpiece and make spray path planning, with high spraying efficiency and no dead angles.

[0085] (4) The substrate with the coating in step (3) is placed in a drying furnace at 100-220°C. The coating is melted, solidified and leveled after high-temperature baking to obtain a substrate with a powder coating on the surface.

[0086] Example 1

[0087] The environmentally friendly coating of this embodiment is made of the following raw materials in parts by weight: The bio-based resin is a monophenolic epoxy resin and a cellulose polyester, and the weight parts thereof are 64 parts; The weight proportion of filler is 30.65 parts; including hydroxyethyl cellulose and titanium dioxide, with a mass ratio of 2:5; The leveling agent is isooctyl acrylate, and its weight portion is 1.5 parts; The curing agent is aromatic diamine, and its weight portion is 0.3 parts.

[0088] Other additives include matting agents, pigments, etc., and their weight parts are 3.55 parts.

[0089] According to the instructions attached Figure 1 The process shown is used to prepare environmentally friendly coatings.

[0090] The performance of the environmentally friendly coating prepared in Example 1 was characterized, and the results are shown in Table 1. It is proved that the coating has high mechanical strength, good adhesion and good fluidity.

[0091] Table 1

[0092] Example 2

[0093] The spraying method of the environmentally friendly coating of this embodiment includes: (1) Pretreatment: Spray the substrate surface with a spray system to remove the Oil, slight oxidation and dust and other pollutants are removed to provide a good base suitable for spraying; the passivation liquid is sprayed on the cleaned substrate surface to form a uniform passivation film on the substrate surface to enhance the adhesion of the coating to the substrate surface. The passivation liquid can be a trivalent chromium passivator or a cyanide-free alkaline copper plating complexing agent.

[0094] (2) Drying: Preheat the substrate to 200°C to dry the moisture on the surface of the substrate; (3) Electrostatic spraying: The environmentally friendly coating of the present invention is sprayed onto the passivation film of the substrate by an electrostatic spraying process, wherein the particle size of the coating is 35 μm, to obtain a substrate with the coating attached; The voltage of electrostatic spraying is 75KV; the current is 20-90uA; the powder output is 90g / min.

[0095] (4) The substrate with the coating in step (3) is placed in a 200° C. drying furnace. The coating is melted, solidified and leveled through high-temperature baking to obtain a substrate with a powder coating on the surface.

[0096] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0097] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An environmentally friendly coating, characterized in that: The environmentally friendly coating is made of the following raw materials in parts by weight: Bio-based resin, its weight part is greater than or equal to 20 parts, its weight part is less than or equal to 70 parts; filler, its weight part is greater than or equal to 10 parts, its weight part is less than or equal to 40 parts; The filler comprises an organic filler and an inorganic filler, the mass ratio of the organic filler to the inorganic filler is greater than or equal to 1 / 9, and the mass ratio of the organic filler to the inorganic filler is less than or equal to 9; The organic filler includes at least one of lignin-based carbon fibers, microcrystalline cellulose, and cellulose derivatives.

2. The environmentally friendly coating according to claim 1, characterized in that: The bio-based resin is prepared from biomaterials. The biomaterials include bio-based epoxy resins using plant phenol as raw materials, and derivatives using cellulose, starch and chitin as base materials.

3. The environmentally friendly coating according to claim 2, characterized in that: The bio-based epoxy resin includes a monophenol type epoxy resin and / or a polyphenol type epoxy resin.

4. The environmentally friendly coating according to claim 2, characterized in that: The derivatives based on cellulose, starch and chitosan include cellulose aliphatic polyester and / or chitosan aliphatic polyester.

5. The environmentally friendly coating according to claim 1, characterized in that: The inorganic filler includes at least one of titanium dioxide, silicon powder and barium sulfate.

6. The environmentally friendly coating according to claim 1, characterized in that: The environmentally friendly coating comprises a leveling agent, wherein the weight portion of the leveling agent is greater than or equal to 0.1 parts, and the weight portion of the leveling agent is less than or equal to 3 parts.

7. The environmentally friendly coating according to claim 6, characterized in that: The leveling agent includes an acrylic leveling agent and / or a polyether leveling agent.

8. The environmentally friendly coating according to claim 1, characterized in that: The environmentally friendly coating includes a curing agent, the weight portion of the curing agent is greater than or equal to 0.5 parts, and the weight portion of the curing agent is less than or equal to 15 parts; The curing agent includes at least one of aliphatic amines, aromatic amines, polyamines and acid anhydrides.

9. The method for spraying an environmentally friendly coating according to any one of claims 1 to 8, characterized in that: The spraying method of the environmentally friendly coating comprises the following steps: (1) Pre-treat the substrate to be sprayed, and remove pollutants such as oil, slight oxidation and dust on the surface of the substrate through a spray system; spray the passivation liquid on the cleaned substrate surface to form a passivation film on the substrate surface; (2) Drying the substrate so that the substrate is preheated to 100°C-220°C; (3) spraying the environmentally friendly coating onto the passivation film of the substrate using an electrostatic spraying process to obtain a powder coating; (4) The substrate with the powder coating in step (3) is placed in a drying furnace at 100-220°C. The coating is melted, solidified and leveled after high-temperature baking to obtain a substrate with a powder coating on the surface.

10. The method for spraying environmentally friendly coating according to claim 9, characterized in that: In the step (1), the passivation solution comprises a chromium passivation solution and / or a non-cyanide complexing agent; In step (3), the voltage of electrostatic spraying is greater than or equal to 20KV, and the voltage of electrostatic spraying is less than The voltage is greater than or equal to 100 KV; the current of electrostatic spraying is greater than or equal to 3uA, the current of electrostatic spraying is less than or equal to 95uA; the powder output is greater than or equal to 15g / min, the powder output is less than or equal to 95g / min.

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