Outdoor weather-resistant scratch-resistant high-hardness powder coating as well as preparation method and application thereof

Abstract

The invention provides an outdoor weather-resistant scratch-resistant high-hardness powder coating as well as a preparation method and application thereof. The super-weather-resistant coating comprises the following raw materials: 54-65% of super-weather-resistant polyester resin, 4.0-4.8% of a curing agent, 0.7-1.2% of a leveling agent, 0.5-0.7% of a wetting accelerant, 0.3-0.6% of a wear-resistant additive, 5-15% of an inert filler, 5-25% of an active composite molten filler, 5-15% of titanium dioxide and 0-0.5% of a pigment. The active composite molten filler is a mixture composed of feldspar powder, glass fibers and silane coupling agent modified wollastonite according to the mass ratio of (2-4): (3-4): (2-4), and the length-diameter ratio of the glass fibers is any one or more of 7: 1, 13: 1 and 15: 1. The weather resistance, the friction resistance and the hardness of the powder coating are greatly improved, and the powder coating is particularly suitable for being sprayed on outdoor furniture and outdoor equipment, such as park benches and fitness equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of powder coatings, in particular to a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, and a preparation method and application thereof. Background Art

[0002] Powder coatings are synthetic resin coatings in a solid powder form, composed of solid resins, pigments, fillers, and additives. Unlike conventional solvent-based and water-based coatings, powder coatings use air as their dispersion medium, rather than solvent and water. Therefore, powder coatings are solvent-free, have 100% film-forming properties, and consume very little energy.

[0003] Outdoor furniture and equipment, such as park benches and outdoor fitness equipment, are increasingly used. These items are exposed to the elements, including UV rays, moisture, and chemicals, and are susceptible to degradation, including gloss loss, discoloration, chalking, blistering, and peeling, which shortens their service life. Furthermore, due to the uncertainties of the outdoor environment, these items are susceptible to bumps and scratches, leading to surface damage. Therefore, there is a need for a weather-resistant, scratch-resistant, and high-hardness powder coating suitable for outdoor use.

[0004] Some weather-resistant, scratch-resistant, and high-hardness powder coatings have emerged in the prior art. For example, Chinese patent CN111073470A, published on April 28, 2020, discloses a friction-resistant, anti-fading powder coating specifically for bicycles. The components and weight proportions of this friction-resistant, anti-fading powder coating for bicycles are: 63-69 parts polyester resin, 4.2-5.1 parts TGIC, 14-23 parts filler, 1-10 parts rutile titanium dioxide, 2-15 parts homemade colorant, and 3.1-3.9 parts additive, which is a mixture of a leveling agent, a degassing agent, and a UV absorber. This powder coating forms a coating on the surface of a bicycle with good leveling and high gloss. It also has significantly improved wear resistance compared to ordinary powder coatings, does not fade when wiped, and has excellent decorative and protective properties, providing decorative and protective properties for bicycles. However, due to the unreasonable formula design, the artificial aging resistance of this friction-resistant and anti-fading powder coating is only 1000 hours, and it cannot withstand the erosion of ultraviolet rays, water vapor and chemical media for a long time; moreover, the scratch resistance of this friction-resistant and anti-fading powder coating is low, which cannot meet the powder coating requirements of outdoor furniture and outdoor equipment such as park benches and fitness equipment. Summary of the Invention

[0005] The purpose of the present invention is to provide a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, a preparation method and application thereof, aiming to solve the problem that the weather-resistant and scratch-resistant powder coatings in the prior art have insufficient weather resistance and low scratch resistance due to unreasonable formula design and cannot meet the powder coating requirements of outdoor furniture and equipment such as park benches and fitness equipment.

[0006] In order to solve the above technical problems, the technical solution of the present invention is achieved as follows:

[0007] In one aspect, the present invention provides a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, comprising the following raw materials in percentage by weight: 54-65% super weather-resistant polyester resin, 4.0-4.8% curing agent, 0.7-1.2% leveling agent, 0.5-0.7% wetting promoter, 0.3-0.6% wear-resistant additive, 5-15% inert filler, 5-25% active composite melt filler, 5-15% titanium dioxide, and 0-0.5% pigment; the active composite melt filler is a mixture of feldspar powder, glass fiber, and silane coupling agent-modified wollastonite in a mass ratio of 2-4:3-4:2-4, and the aspect ratio of the glass fiber is any one or more of 7:1, 13:1, and 15:1.

[0008] The present invention's weather-resistant, scratch-resistant, high-hardness outdoor powder coating is primarily based on a super-weather-resistant polyester resin, which exhibits excellent weather resistance, good chemical resistance, superior mechanical properties, and high decorative properties. This resin undergoes a curing and cross-linking reaction with a curing agent. Through the combined action of an active composite melt-forming filler, a wear-resistant additive, a leveling agent, a wetting promoter, an inert filler, titanium dioxide, and a pigment, a well-leveled, dense cured coating film is formed. The active composite melt-forming filler, composed of feldspar powder, glass fiber, and silane-coupling-agent-modified wollastonite, fully and evenly fills the three-dimensional network formed by the super-weather-resistant polyester resin and curing agent during the curing and cross-linking reaction. The spherical feldspar powder, embedded in the relatively large spaces, acts as a framework, enhancing the coating's hardness and acid and alkali resistance. The flaky silane-coupling agent-modified wollastonite, embedded in the relatively flat spaces, acts as a bridge, effectively improving the inorganic-organic interface within the coating and strengthening the bond between the inert filler and the super-weather-resistant polyester resin. Fine, needle-shaped glass fibers, inserted into the elongated gaps, act as bridges, enhancing the coating's hardness and scratch resistance while also imparting flexibility. The three components of this active composite melt filler complement and reinforce each other, effectively filling the three-dimensional network formed by the super-weather-resistant polyester resin and curing agent. This effective filling significantly improves the coating's weather resistance, friction resistance, and hardness. Furthermore, during the curing and crosslinking reaction, the wear-resistant additive melts and migrates to the coating's surface, reducing surface friction and further enhancing its friction resistance.

[0009] The weather-resistant and scratch-resistant high-hardness powder coating for outdoor use of the present invention, under the synergistic effect of a super-weather-resistant polyester resin, a curing agent, an active composite melt filler, a wear-resistant additive, a leveling agent, a wetting promoter, an inert filler, titanium dioxide, and a pigment, avoids potential weak spots in the resulting coating film and can effectively resist long-term erosion by ultraviolet rays, water vapor, chemical media, and the like in the external environment. It has a pencil hardness of 5H and can withstand direct and reverse impacts of 50 cm·kg. Under ultraviolet accelerated aging conditions, it achieves a gloss loss level of 1 and a discoloration level of 0 after 3000 hours. Therefore, the weather resistance, friction resistance, and hardness of the powder coating are greatly improved, meeting the long-term protection and aesthetic requirements of outdoor furniture and outdoor equipment, and extending the service life of outdoor furniture and equipment such as park benches and fitness equipment.

[0010] As a preferred embodiment, the outdoor weather-resistant, scratch-resistant, high-hardness powder coating has an average particle size of 36-42 μm. The outdoor weather-resistant, scratch-resistant, high-hardness powder coating of the present invention exists in a fine powder state and is electrostatically sprayed onto the surfaces of outdoor furniture and equipment such as park benches and fitness equipment. It is then heated, undergoing melting, chemical crosslinking, and curing, forming a well-leveled, dense cured coating film.

[0011] In a preferred embodiment, the wear-resistant additive is a white powder of micronized polytetrafluoroethylene-modified polyethylene wax, having a melting point between 130°C and 150°C and a purity of no less than 99%. The wear-resistant additive of the present invention has a low melting point and migrates to the surface of the coating during the powder coating's melting and curing process, thereby reducing the coating's surface friction and effectively improving the coating's scratch resistance.

[0012] As a preferred embodiment, the super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin having an acid value of 30-36 mgKOH / g and a glass transition temperature of 63-70°C. This super-weather-resistant polyester resin has a relatively moderate acid value, high and easy-to-control reactivity, a fast curing speed, and a stable cross-linked structure. The resulting coating film has improved gloss and color uniformity, as well as water resistance and chemical resistance. It can resist erosion by ultraviolet rays, water vapor, and the like in external high-temperature environments and has excellent weather resistance. In addition, this super-weather-resistant polyester resin also has a high glass transition temperature. The resulting coating film is hard, soft, and elastic, resistant to scratches and wear, and can adapt to a certain degree of deformation and stretching. It can also resist erosion by ultraviolet rays and thermal stress in external high-temperature environments, has excellent weather resistance, and is highly reliable during long-term outdoor use.

[0013] As a preferred embodiment, the curing agent is triglycidyl isocyanurate with an epoxy value of 0.93-0.98 mol / 100g. The curing agent of the present invention closely cooperates with the super-weather-resistant polyester resin. The carboxyl groups in the super-weather-resistant polyester resin and the epoxy groups in the curing agent undergo a sufficient and rapid ring-opening addition reaction, which accelerates the curing reaction speed, forms more cross-linking points, increases the cross-linking density, and makes the three-dimensional network structure more stable. This improves the hardness, weather resistance, and scratch resistance of the resulting coating film, and prevents powdering, gloss loss, and shedding under long-term erosion by the external environment.

[0014] As a preferred embodiment, the leveling agent is a silica-adsorbed acrylate copolymer. This leveling agent effectively promotes the fluidity of powder coatings during melting, thereby effectively preventing the formation of orange peel and shrinkage craters. It also improves the smoothness and glossiness of the coating, resulting in a more decorative effect. It also enhances the adhesion of the coating, making it less likely to fall off or peel during use. The silica-adsorbed acrylate copolymer leveling agent of the present invention exhibits excellent stability and unique surface properties. Furthermore, the synergistic effect between silica and the acrylate copolymer results in strong adsorption capacity, further improving the overall performance of the coating.

[0015] As a preferred embodiment, the wetting promoter is polymethacrylate. On the one hand, the wetting promoter works closely with the leveling agent to reduce the surface tension of the powder coating in the molten state, improving the anti-pollution performance of the coating, avoiding the formation of craters or pinholes, and improving the integrity, decorativeness, and protective properties of the coating. On the other hand, it works closely with the pigment to uniformly disperse the pigment in the powder coating, improving the color uniformity and appearance quality of the coating. At the same time, it can also promote the curing reaction, helping to improve the weather resistance, chemical resistance, friction resistance, and hardness of the coating. The polymethacrylate wetting promoter of the present invention has excellent wetting properties, good compatibility, and stable chemical properties, further improving the overall performance of the coating.

[0016] As a preferred embodiment, the filler is any one or more of barium sulfate, calcium carbonate, and silicon powder. The filler of the present invention includes but is not limited to barium sulfate, calcium carbonate, or silicon powder, and barium sulfate is preferably used. It can fill the coating skeleton, improve the mechanical properties of the coating, and make the coating surface smooth and clean.

[0017] As a preferred embodiment, the titanium dioxide is rutile titanium dioxide. The rutile titanium dioxide of the present invention provides excellent hiding power for the coating film and also has good weather resistance, thereby improving the overall performance of the coating film.

[0018] As a preferred embodiment, the pigment is any one or more of carbon black pigment, iron red pigment, and iron yellow pigment. The carbon black pigment, iron red pigment, and iron yellow pigment of the present invention are easy to produce, widely used, have strong tinting power, and have good weather resistance.

[0019] In another aspect, the present invention provides a method for preparing a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, comprising the following steps: 1) weighing a super-weather-resistant polyester resin, a curing agent, a leveling agent, a wetting promoter, a wear-resistant additive, an inert filler, an active composite melt filler, titanium dioxide, and a pigment, mixing and stirring to obtain a mixture; 2) placing the mixture obtained in step 1) in a twin-screw extruder, melting, mixing, and extruding the mixture; the temperature of zone 1 of the twin-screw extruder is 95-105°C, the temperature of zone 2 is 105-115°C, and the temperature of zone 3 is 115-125°C to obtain a sheet; 3) cooling, crushing, and grinding the sheet obtained in step 2) to obtain a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use.

[0020] The preparation method of the weather-resistant, scratch-resistant, high-hardness outdoor powder coating of the present invention is to first mix the raw materials evenly, then place them in a twin-screw extruder for melting, mixing, extrusion, cooling, crushing and grinding. This preparation method is simple to operate, has mild conditions, has low requirements on equipment performance, is easy to achieve industrial continuous production, and has high production efficiency.

[0021] As a preferred embodiment, in step 1), stirring is performed in a mixer for 5-8 minutes; and in step 3), grinding is performed in a grinder with a primary mill speed of 40-45 Hz and a secondary mill speed of 25-35 Hz. Stirring in a mixer is simple, uniform, and easy to control. Furthermore, grinding in a grinder allows for control of the primary and secondary mill speeds to adjust the particle size after grinding, resulting in convenient control and excellent grinding results.

[0022] In yet another aspect, the present invention provides an application of an outdoor weather-resistant, scratch-resistant, high-hardness powder coating, wherein the outdoor weather-resistant, scratch-resistant, high-hardness powder coating is used on outdoor furniture and / or outdoor fitness equipment.

[0023] The outdoor weather-resistant, scratch-resistant, high-hardness powder coating of the present invention is particularly suitable for spraying on outdoor furniture and outdoor equipment, such as park benches and fitness equipment. When the outdoor furniture and outdoor equipment are exposed to the outdoor wind and sun for a long time, they are not easily affected by the external environment or bumped and damaged, resulting in bruises, scratches or scrapes. They can also effectively resist long-term erosion by ultraviolet rays, water vapor, chemical media, etc. in the external environment, and can remain discolored, powdered, blistered, peeled, and glossy for a long time, fully ensuring the long-term protection and aesthetics of the outdoor furniture and outdoor equipment.

[0024] Compared with the prior art, the present invention has the following beneficial effects: the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention, under the synergistic effect of super-weather-resistant polyester resin, curing agent, active composite melt filler, wear-resistant additive, leveling agent, wetting promoter, inert filler, titanium dioxide and pigment, the obtained coating film avoids potential weak spots and can effectively resist long-term erosion by ultraviolet rays, water vapor, chemical media and the like in the external environment, has a pencil hardness of 5H, can withstand 50cm·kg positive and negative impacts, and reaches a gloss loss level of 1 and a color change level of 0 after 3000h under ultraviolet accelerated aging conditions, thereby greatly improving the powder coating. The weather resistance, friction resistance, and hardness of the powder coating make it particularly suitable for spraying onto outdoor furniture and equipment, such as park benches and fitness equipment. The outdoor furniture and equipment using this weather-resistant, scratch-resistant, high-hardness powder coating are not easily affected by the external environment or bumps and bruises, scratches, or scratches when exposed to wind and sun for a long time. The coating remains colorless, powdery, blistering, peeling, and gloss-free for a long time, fully ensuring the long-term protection and aesthetics of the outdoor furniture and equipment, and extending the service life of outdoor furniture and equipment such as park benches and fitness equipment. The method for preparing the weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use of the present invention is simple to operate, requires mild conditions, has low equipment performance requirements, facilitates industrialized continuous production, and has high production efficiency. DETAILED DESCRIPTION

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] The invention discloses a weather-resistant, scratch-resistant, and high-hardness powder coating for outdoor use, comprising the following raw materials in percentage by weight: 54-65% of a super-weather-resistant polyester resin, 4.0-4.8% of a curing agent, 0.7-1.2% of a leveling agent, 0.5-0.7% of a wetting promoter, 0.3-0.6% of a wear-resistant additive, 5-15% of an inert filler, 5-25% of an active composite melt filler, 5-15% of titanium dioxide, and 0-0.5% of a pigment. The active composite melt filler is a mixture of feldspar powder, glass fiber, and wollastonite modified with a silane coupling agent in a mass ratio of 2-4:3-4:2-4, and the aspect ratio of the glass fiber is any one or more of 7:1, 13:1, and 15:1.

[0027] Preferably, the average particle size of the outdoor weather-resistant, scratch-resistant and high-hardness powder coating is 36-42 μm.

[0028] Preferably, the wear-resistant additive is a white powder of micronized polytetrafluoroethylene-modified polyethylene wax, the melting point of the wear-resistant additive is between 130-150° C., and the purity of the wear-resistant additive is not less than 99%.

[0029] Preferably, the super weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin having an acid value of 30-36 mgKOH / g and a glass transition temperature of 63-70°C.

[0030] Preferably, the curing agent is triglycidyl isocyanurate with an epoxy value of 0.93-0.98 mol / 100g.

[0031] Preferably, the leveling agent is a silica-adsorbed acrylate copolymer.

[0032] Preferably, the wetting promoter is polymethacrylate.

[0033] Preferably, the filler is any one or more of barium sulfate, calcium carbonate, and silicon powder.

[0034] Preferably, the titanium dioxide is rutile titanium dioxide.

[0035] Preferably, the pigment is any one or more of carbon black pigment, iron red pigment, and iron yellow pigment.

[0036] The present invention provides a method for preparing a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, comprising the following steps:

[0037] 1) weighing a super weather-resistant polyester resin, a curing agent, a leveling agent, a wetting promoter, a wear-resistant additive, an inert filler, an active composite melt filler, titanium dioxide and a pigment, mixing and stirring to obtain a mixed material;

[0038] 2) placing the mixture obtained in step 1) in a twin-screw extruder, melting, mixing, and extruding, wherein the temperature of the first zone of the twin-screw extruder is 95-105° C., the temperature of the second zone is 105-115° C., and the temperature of the third zone is 115-125° C., to obtain a sheet;

[0039] 3) Cooling, crushing, and grinding the sheet obtained in step 2) to obtain a weather-resistant, scratch-resistant, and high-hardness powder coating for outdoor use.

[0040] Preferably, in step 1), stirring is performed in a mixer for 5-8 min; in step 3), grinding is performed in a grinder with a main grinding speed of 40-45 Hz and a secondary grinding speed of 25-35 Hz.

[0041] The invention discloses an application of an outdoor weather-resistant, scratch-resistant, high-hardness powder coating, wherein the outdoor weather-resistant, scratch-resistant, high-hardness powder coating is used on outdoor furniture and / or outdoor fitness equipment.

[0042] Example 1

[0043] The present invention provides a method for preparing a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, comprising the following steps:

[0044] 1) Weigh the following raw materials in parts by weight:

[0045] 54Kg of super-weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting accelerator, 0.3Kg of wear-resistant additive, 10Kg of inert filler, 25Kg of active composite melt filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0046] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 36 mgKOH / g and a glass transition temperature of 63°C; the curing agent is triglycidyl isocyanurate with an epoxy value of 0.98 eq / 100g; the leveling agent is a silica-adsorbed acrylate copolymer; the wetting promoter is polymethacrylate; the wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder with a melting point between 130-150°C and a purity of not less than 99%; the inert filler is barium sulfate; the active composite melt-forming filler is a mixture of feldspar powder, glass fiber, and silane coupling agent-modified wollastonite in a mass ratio of 2:3:2, and the aspect ratio of the glass fiber is 7:1; the titanium dioxide is rutile titanium dioxide; and the pigment is carbon black pigment.

[0047] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0048] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0049] 4) The sheet was cooled and crushed, and then ground in a mill with the main mill rotating at 40 Hz and the auxiliary mill rotating at 25 Hz to obtain a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use with an average particle size of 42 μm.

[0050] Example 2

[0051] The present invention provides a method for preparing a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, comprising the following steps:

[0052] 1) Weigh the following raw materials in parts by weight:

[0053] 55.5Kg of super-weather-resistant polyester resin, 4.5Kg of curing agent, 1.0Kg of leveling agent, 0.6Kg of wetting promoter, 0.4Kg of wear-resistant additive, 5Kg of inert filler, 18Kg of active composite melt filler, 15Kg of titanium dioxide, a total of 100Kg;

[0054] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 33 mgKOH / g and a glass transition temperature of 65°C. The curing agent is triglycidyl isocyanurate with an epoxy value of 0.95 eq / 100g. The leveling agent is a silica-adsorbed acrylate copolymer. The wetting promoter is polymethacrylate. The wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder with a melting point between 130-150°C and a purity of not less than 99%. The inert filler is calcium carbonate. The active composite melt-forming filler is a mixture of feldspar powder, glass fiber, and silane coupling agent-modified wollastonite in a mass ratio of 1:2:1, and the aspect ratio of the glass fiber is 13:1. The titanium dioxide is rutile titanium dioxide.

[0055] 2) Place the above raw materials in a mixer, mix and stir for 7 minutes to obtain a uniform mixture;

[0056] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, the temperature of the twin-screw extruder zone 1 is 100° C., the temperature of the second zone is 110° C., and the temperature of the third zone is 120° C. to obtain a sheet;

[0057] 4) The sheet was cooled and crushed, and then ground in a mill with the main mill rotating at 45 Hz and the auxiliary mill rotating at 35 Hz to obtain a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use with an average particle size of 36 μm.

[0058] Example 3

[0059] The present invention provides a method for preparing a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, comprising the following steps:

[0060] 1) Weigh the following raw materials in parts by weight:

[0061] 65Kg of super-weather-resistant polyester resin, 4.8Kg of curing agent, 1.2Kg of leveling agent, 0.7Kg of wetting accelerator, 0.6Kg of wear-resistant additive, 15Kg of inert filler, 5Kg of active composite melt filler, 7.5Kg of titanium dioxide, 0.2Kg of pigment, a total of 100Kg;

[0062] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 30 mgKOH / g and a glass transition temperature of 70°C. The curing agent is triglycidyl isocyanurate with an epoxy value of 0.93 eq / 100g. The leveling agent is a silica-adsorbed acrylate copolymer. The wetting promoter is polymethacrylate. The wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder with a melting point between 130-150°C and a purity of not less than 99%. The inert filler is silica powder. The active composite melt filler is a mixture of feldspar powder, glass fiber, and silane coupling agent-modified wollastonite in a mass ratio of 1:2:2, and the aspect ratio of the glass fiber is 15:1. The titanium dioxide is rutile titanium dioxide, and the pigment is iron red pigment.

[0063] 2) Place the above raw materials in a mixer, mix and stir for 8 minutes to obtain a uniform mixture;

[0064] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, the temperature of the twin-screw extruder zone 1 is 105° C., the temperature of the second zone is 115° C., and the temperature of the third zone is 125° C. to obtain a sheet;

[0065] 4) The sheet was cooled and crushed, and then ground in a mill with the main mill rotating at 43 Hz and the auxiliary mill rotating at 30 Hz to obtain a weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use with an average particle size of 39 μm.

[0066] Comparative Example 1

[0067] On the basis of Example 1, the active composite melt filler is not used, and other conditions are the same, namely:

[0068] 1) Weigh the following raw materials in parts by weight:

[0069] 54Kg of super weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting promoter, 0.3Kg of wear-resistant additive, 35Kg of inert filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0070] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 36 mgKOH / g and a glass transition temperature of 63°C. The curing agent is triglycidyl isocyanurate with an epoxy value of 0.98 eq / 100g. The leveling agent is a silica-adsorbed acrylate copolymer. The wetting promoter is polymethacrylate. The wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder with a melting point between 130°C and 150°C and a purity of not less than 99%. The inert filler is barium sulfate. The titanium dioxide is rutile titanium dioxide. The pigment is carbon black pigment.

[0071] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0072] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0073] 4) The above-mentioned sheet was cooled and crushed, and then placed in a grinding mill for grinding. The main grinding speed was 40 Hz and the auxiliary grinding speed was 25 Hz to obtain a powder coating with an average particle size of 42 μm, which was recorded as control sample 1.

[0074] Comparative Example 2

[0075] On the basis of Example 1, the composite molten filler is a mixture of feldspar powder and glass fiber, and other conditions are the same, namely:

[0076] 1) Weigh the following raw materials in parts by weight:

[0077] 54Kg of super-weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting accelerator, 0.3Kg of wear-resistant additive, 10Kg of inert filler, 25Kg of composite melt filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0078] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin having an acid value of 36 mgKOH / g and a glass transition temperature of 63°C; the curing agent is triglycidyl isocyanurate having an epoxy value of 0.98 eq / 100g; the leveling agent is a silica-adsorbed acrylate copolymer; the wetting promoter is polymethacrylate; the wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder having a melting point between 130°C and 150°C and a purity of not less than 99%; the inert filler is barium sulfate; the composite molten filler is a mixture of feldspar powder and glass fiber in a mass ratio of 2:3, and the aspect ratio of the glass fiber is 7:1; the titanium dioxide is rutile titanium dioxide; and the pigment is carbon black pigment.

[0079] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0080] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0081] 4) The above-mentioned sheet was cooled and crushed, and then placed in a grinding mill for grinding. The main grinding speed was 40 Hz and the auxiliary grinding speed was 25 Hz to obtain a powder coating with an average particle size of 42 μm, which was recorded as control sample 2.

[0082] Comparative Example 3

[0083] On the basis of Example 1, the composite molten filler is a mixture of feldspar powder and wollastonite modified with a silane coupling agent, and other conditions are the same, namely:

[0084] 1) Weigh the following raw materials in parts by weight:

[0085] 54Kg of super-weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting accelerator, 0.3Kg of wear-resistant additive, 10Kg of inert filler, 25Kg of composite melt filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0086] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 36 mgKOH / g and a glass transition temperature of 63°C. The curing agent is triglycidyl isocyanurate with an epoxy value of 0.98 eq / 100g. The leveling agent is a silica-adsorbed acrylate copolymer. The wetting promoter is polymethacrylate. The wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder with a melting point between 130°C and 150°C and a purity of not less than 99%. The inert filler is barium sulfate. The composite molten filler is a mixture of feldspar powder and silane coupling agent-modified wollastonite in a mass ratio of 1:1. The titanium dioxide is rutile titanium dioxide, and the pigment is carbon black.

[0087] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0088] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0089] 4) The above-mentioned sheet was cooled and crushed, and then placed in a grinding mill for grinding. The main grinding speed was 40 Hz and the auxiliary grinding speed was 25 Hz to obtain a powder coating with an average particle size of 42 μm, which was recorded as control sample 3.

[0090] Comparative Example 4

[0091] On the basis of Example 1, the composite molten filler is a mixture of glass fiber and wollastonite modified with a silane coupling agent, and other conditions are the same, namely:

[0092] 1) Weigh the following raw materials in parts by weight:

[0093] 54Kg of super-weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting accelerator, 0.3Kg of wear-resistant additive, 10Kg of inert filler, 25Kg of composite melt filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0094] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 36 mgKOH / g and a glass transition temperature of 63°C; the curing agent is triglycidyl isocyanurate with an epoxy value of 0.98 eq / 100g; the leveling agent is a silica-adsorbed acrylate copolymer; the wetting promoter is polymethacrylate; the wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder with a melting point between 130°C and 150°C and a purity of not less than 99%; the inert filler is barium sulfate; the composite molten filler is a mixture of glass fiber and silane coupling agent-modified wollastonite in a mass ratio of 3:2, and the aspect ratio of the glass fiber is 7:1; the titanium dioxide is rutile titanium dioxide; and the pigment is carbon black pigment.

[0095] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0096] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0097] 4) The above-mentioned sheet was cooled, crushed, and placed in a grinding mill for grinding. The main grinding speed was 40 Hz and the auxiliary grinding speed was 25 Hz to obtain a powder coating with an average particle size of 42 μm, which was recorded as control sample 4.

[0098] Comparative Example 5

[0099] On the basis of Example 1, the ratios of feldspar powder, glass fiber and wollastonite modified by silane coupling agent in the composite molten filler are different, and other conditions are the same, namely:

[0100] 1) Weigh the following raw materials in parts by weight:

[0101] 54Kg of super-weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting accelerator, 0.3Kg of wear-resistant additive, 10Kg of inert filler, 25Kg of composite melt filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0102] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin having an acid value of 36 mgKOH / g and a glass transition temperature of 63°C; the curing agent is triglycidyl isocyanurate having an epoxy value of 0.98 eq / 100g; the leveling agent is a silica-adsorbed acrylate copolymer; the wetting promoter is polymethacrylate; the wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder having a melting point between 130°C and 150°C and a purity of not less than 99%; the inert filler is barium sulfate; the composite molten filler is a mixture of feldspar powder, glass fiber, and silane coupling agent-modified wollastonite in a mass ratio of 1:2:6, and the aspect ratio of the glass fiber is 7:1; the titanium dioxide is rutile titanium dioxide; and the pigment is carbon black pigment.

[0103] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0104] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0105] 4) The above-mentioned sheet was cooled and crushed, and then placed in a grinding mill for grinding. The main grinding speed was 40 Hz and the auxiliary grinding speed was 25 Hz to obtain a powder coating with an average particle size of 42 μm, namely, control sample 5.

[0106] Comparative Example 6

[0107] On the basis of Example 1, the aspect ratio of the glass fiber in the composite melt filler is different, and other conditions are the same, that is:

[0108] 1) Weigh the following raw materials in parts by weight:

[0109] 54Kg of super-weather-resistant polyester resin, 4.0Kg of curing agent, 0.7Kg of leveling agent, 0.5Kg of wetting accelerator, 0.3Kg of wear-resistant additive, 10Kg of inert filler, 25Kg of composite melt filler, 5Kg of titanium dioxide, 0.5Kg of pigment, a total of 100Kg;

[0110] The super-weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin having an acid value of 36 mgKOH / g and a glass transition temperature of 63°C; the curing agent is triglycidyl isocyanurate having an epoxy value of 0.98 eq / 100g; the leveling agent is a silica-adsorbed acrylate copolymer; the wetting promoter is polymethacrylate; the wear-resistant additive is a micronized polytetrafluoroethylene-modified polyethylene wax white powder having a melting point between 130°C and 150°C and a purity of not less than 99%; the inert filler is barium sulfate; the composite molten filler is a mixture of feldspar powder, glass fiber, and silane coupling agent-modified wollastonite in a mass ratio of 2:3:2, and the aspect ratio of the glass fiber is 17:1; the titanium dioxide is rutile titanium dioxide; and the pigment is carbon black pigment.

[0111] 2) Place the above raw materials in a mixer, mix and stir for 5 minutes to obtain a uniform mixture;

[0112] 3) placing the above-mentioned mixed material in a twin-screw extruder, melting, mixing, and extruding, with the temperature of the first zone of the twin-screw extruder being 95° C., the temperature of the second zone being 105° C., and the temperature of the third zone being 115° C., to obtain a sheet;

[0113] 4) The above-mentioned sheet was cooled, crushed, and placed in a grinding mill for grinding. The main grinding speed was 40 Hz and the auxiliary grinding speed was 25 Hz to obtain a powder coating with an average particle size of 42 μm, namely, control sample 6.

[0114] Three outdoor weather-resistant, scratch-resistant, high-hardness powder coatings obtained from Examples 1 to 3 of the present invention, as well as control samples 1 to 6 obtained from Comparative Examples 1 to 6, and commercially available general-purpose ordinary powder coatings were sprayed onto galvanized sheets using an electrostatic spray gun with the same spraying process parameters, i.e., at an electrostatic spray gun voltage of 60 kV. Each was then cured in an oven at 200°C for 15 minutes to obtain a complete coating film. The appearance of the resulting coating film was then observed, and corresponding performance tests were performed. The test items included 60° gloss, impact resistance, pencil hardness, and ultraviolet accelerated (QUVA) aging tests. The experimental results are listed in Table 1.

[0115] Among them, the 60° gloss is tested according to the method specified in GBT 9754-2007 Paints and varnishes - 60° mirror gloss of paint films without metallic pigments. A 60° gloss meter is used to read 6 numbers at different parts or directions of the coating surface, and then the average value is taken; the impact resistance is tested according to GBT 1732-1993 Determination of impact resistance of paint films, and the forward impact performance and backlash performance of the coating are tested respectively; the pencil hardness is tested according to the method specified in GBT 6739-2006 Paints and varnishes - Pencil method for determination of paint film hardness. A pencil is pressed downward at a 45° angle on the coating surface under a load of 750g, and pushed at a speed of 0.5-1mm / s for a distance of at least 7mm. The pencil hardness of the coating is expressed as the hardest pencil hardness that does not cause scratches of 3mm or more on the coating; the UV accelerated aging test is tested according to GBT 14522-2008 Test method for artificial weathering of plastics, coatings, and rubber materials for mechanical industrial products. Tests were conducted using fluorescent UV lamps. The test conditions used exposure cycle type 1, which uses a UVA-340nm light source with an irradiance of 0.89W / m 2 , drying at 60℃ for 8h, condensing at 50℃ for 4h, and the results were evaluated using the rating method for aging of paints and varnishes in GBT 1766-2008.

[0116] Table 1 Performance test results of different powder coatings

[0117]

[0118] As can be seen from Table 1, the appearance of the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention after spraying is smooth and flat, and has the same appearance as the commercially available general powder coating; the appearance of the coating of control sample 1, control sample 2, control sample 3, control sample 4, and control sample 5 after spraying is also smooth and flat, and has the same appearance as the commercially available general powder coating; however, control sample 6 has a coarse glass fiber powder due to the excessively large aspect ratio of the glass fiber, and there is residue on the coating surface after spraying.

[0119] As shown in Table 1, the 60° gloss of the sprayed outdoor weather-resistant, scratch-resistant, high-hardness powder coating of the present invention is 72-75°. This is substantially consistent with the 60° gloss of the sprayed coatings of Control Samples 2, 3, 4, 5, and 6. However, the 60° gloss of Control Sample 1 is 86° after spraying, and the gloss of a commercially available general-purpose powder coating is 87° after spraying. Therefore, the 60° gloss of the sprayed outdoor weather-resistant, scratch-resistant, high-hardness powder coating of the present invention is reduced due to the use of an active composite melt-filler.

[0120] It can also be seen from Table 1 that the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention passes both the forward and reverse impacts of 50 cm·Kg after spraying; this is consistent with the forward and reverse impact performance of the coating after spraying of control samples 1, 2, 4, 6 and commercially available general-purpose ordinary powder coatings; however, control samples 3 and 5 do not contain glass fiber in the composite molten filler or the proportion of glass fiber is low, resulting in the forward and reverse impact performance of the coating after spraying passing the forward impact but failing the reverse impact.

[0121] Table 1 also shows that the pencil hardness of the coating films of the present invention's outdoor weather-resistant, scratch-resistant, high-hardness powder coatings after spraying all reached 5H. However, the pencil hardnesses of the coating films of Control Samples 1, 2, 3, 4, 5, and 6 after spraying were 2H, 4H, 3H, 4H, 3H, and 4H, respectively. Furthermore, the pencil hardness of the coating films of commercially available general-purpose powder coatings after spraying was only 1H. Therefore, the coating films of the present invention's outdoor weather-resistant, scratch-resistant, high-hardness powder coatings after spraying exhibited higher pencil hardness and excellent scratch resistance.

[0122] It can be seen from Table 1 that the coating film of the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention after spraying can reach a gloss loss level of 1 and a color change level of 0 after 3000 hours under QUVA aging conditions, and has very excellent weather resistance; however, the coating films of control samples 1, 4, 5 and 6 after spraying can reach a gloss loss level of 1 after 3000 hours under QUVA aging conditions, but their color change level is reduced to 1; the coating film of control sample 2 after spraying has a gloss loss level of 1 and a color change level of 2 after 3000 hours under QUVA aging conditions; the coating film of control sample 3 after spraying has a gloss loss level of 2 and a color change level of 1 after 3000 hours under QUVA aging conditions; and the coating film of commercially available general-purpose ordinary powder coating after spraying has reached a gloss loss level of 5 and a color change level of 5 after 1000 hours under QUVA aging conditions. Therefore, after the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention is sprayed, the weather resistance of the coating film is significantly improved, and it has super weather resistance.

[0123] Therefore, compared with the prior art, the present invention has the following beneficial effects: the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention, under the synergistic effect of super-weather-resistant polyester resin, curing agent, active composite melt filler, wear-resistant additive, leveling agent, wetting promoter, inert filler, titanium dioxide and pigment, the resulting coating avoids potential weak spots and can effectively resist long-term erosion by ultraviolet rays, water vapor, chemical media and the like in the external environment, has a pencil hardness of 5H, can withstand 50cm·kg positive and negative impacts, and reaches a gloss loss level of 1 and a discoloration level of 0 for 3000h under ultraviolet accelerated aging conditions, thereby greatly improving the The powder coating has excellent weather resistance, friction resistance and hardness, and is particularly suitable for spraying on outdoor furniture and outdoor equipment, such as park benches and fitness equipment. When the outdoor furniture and outdoor equipment are exposed to the wind and sun for a long time, they are not easily affected by the external environment or bumped and bruised, scratched or scratched. They can remain discolored, powdered, blistered, peeled or glossy for a long time, fully ensuring the long-term protection and aesthetics of the outdoor furniture and outdoor equipment, and extending the service life of outdoor furniture and equipment such as park benches and fitness equipment. The preparation method of the outdoor weather-resistant and scratch-resistant high-hardness powder coating of the present invention is simple to operate, mild in conditions, has low requirements on equipment performance, is easy to achieve industrial continuous production, and has high production efficiency.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use, characterized in that: The raw materials include the following weight percentages: Super weather-resistant polyester resin 54-65%, curing agent 4.0-4.8%, leveling agent 0.7-1.2%, wetting promoter 0.5-0.7%, wear-resistant additive 0.3-0.6%, inert filler 5-15%, active composite melt filler 5-25%, titanium dioxide 5-15%, pigment 0-0.5%; The active composite melt filler is a mixture of feldspar powder, glass fiber, and wollastonite modified by a silane coupling agent in a mass ratio of 2-4:3-4:2-4. The aspect ratio of the glass fiber is any one or more of 7:1, 13:1, and 15:

1.

2. The outdoor weather-resistant and scratch-resistant high-hardness powder coating according to claim 1, characterized in that: The average particle size of the outdoor weather-resistant, scratch-resistant and high-hardness powder coating is 36-42 μm.

3. The outdoor weather-resistant and scratch-resistant high-hardness powder coating according to claim 1 or 2, characterized in that: The wear-resistant additive is a white powder of micronized polytetrafluoroethylene-modified polyethylene wax. The melting point of the wear-resistant additive is between 130-150° C., and the purity of the wear-resistant additive is not less than 99%.

4. The outdoor weather-resistant and scratch-resistant high-hardness powder coating according to claim 1 or 2, characterized in that: The super weather-resistant polyester resin is a carboxyl-terminated saturated polyester resin with an acid value of 30-36 mgKOH / g and a glass transition temperature of 63-70°C.

5. The weather-resistant, scratch-resistant, high-hardness outdoor powder coating according to claim 1 or 2, characterized in that: The curing agent is triglycidyl isocyanurate with an epoxy value of 0.93-0.98 mol / 100g.

6. The outdoor weather-resistant and scratch-resistant high-hardness powder coating according to claim 1 or 2, characterized in that: The leveling agent is a silica-adsorbed acrylate copolymer; preferably, the wetting promoter is polymethacrylate.

7. The outdoor weather-resistant and scratch-resistant high-hardness powder coating according to claim 1 or 2, characterized in that: The filler is any one or more of barium sulfate, calcium carbonate, and silicon micropowder; preferably, the titanium dioxide is rutile titanium dioxide; preferably, the pigment is any one or more of carbon black pigment, iron red pigment, and iron yellow pigment.

8. A method for preparing the outdoor weather-resistant, scratch-resistant, high-hardness powder coating according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) weighing a super weather-resistant polyester resin, a curing agent, a leveling agent, a wetting promoter, a wear-resistant additive, an inert filler, an active composite melt filler, titanium dioxide and a pigment, mixing and stirring to obtain a mixed material; 2) placing the mixture obtained in step 1) in a twin-screw extruder, melting, mixing, and extruding, wherein the temperature of the first zone of the twin-screw extruder is 95-105° C., the temperature of the second zone is 105-115° C., and the temperature of the third zone is 115-125° C., to obtain a sheet; 3) Cooling, crushing, and grinding the sheet obtained in step 2) to obtain a weather-resistant, scratch-resistant, and high-hardness powder coating for outdoor use.

9. The method for preparing the weather-resistant, scratch-resistant, high-hardness powder coating for outdoor use according to claim 8, characterized in that: In the step 1), stirring is performed in a mixer for 5-8 minutes; in the step 3), grinding is performed in a grinder with a main grinding speed of 40-45 Hz and a secondary grinding speed of 25-35 Hz.

10. Use of the outdoor weather-resistant, scratch-resistant, high-hardness powder coating according to any one of claims 1 to 7, characterized in that: The outdoor weather-resistant, scratch-resistant and high-hardness powder coating is used on outdoor furniture and / or outdoor fitness equipment.

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