A method for producing a powder coating using ultrasonic bonding technology

Abstract

The application provides a method for preparing a powder coating by using an ultrasonic bonding technology, and belongs to the field of powder coating preparation.The method comprises the following steps: mixing to-be-bonded powder particles with a resin powder coating matrix, applying ultrasonic vibration after compression, transmitting ultrasonic energy to the powder particles, making the powder particles vibrate at a high frequency, generating instantaneous high temperature through particle friction, and causing the particles to be bonded; through optimization of ultrasonic process parameters, the to-be-bonded powder particles are bonded in a short time, the prepared powder coating has high dispersity, and the preparation method does not need high-temperature heating, has low energy consumption, and is high in efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of powder coating preparation, more particularly, to a method for preparing powder coating by using ultrasonic bonding technology. BACKGROUND

[0002] As a new type of solvent-free, 100% solid powder coating, powder coating has been widely used in industrial fields in recent years. Its advantages are very obvious. It does not need to use various organic solvents in production and use, avoiding environmental pollution and health hazards caused by traditional coatings. In addition, the utilization efficiency of powder coating is also very high, and the sprayed powder coating can be recycled and reused, with a utilization rate of 99%.

[0003] The key step of powder coating preparation is to uniformly disperse and combine pigments, fillers and additives into the matrix resin. This key step not only determines the uniformity and sprayability of the powder coating, but also directly affects the quality and performance of the final coating. In practical application, efficient and stable preparation method is crucial to improve the decorative, weather resistance and functionality of the coating. However, the existing preparation method still has certain limitations, for example, the melt extrusion method may cause discoloration or performance degradation of heat-sensitive pigments and additives, the dry mixing method may cause uneven dispersion of small particle size particles due to lack of effective bonding, affecting the quality of the coating, and the thermal bonding method may affect the stability and color development effect of pigments due to temperature control challenges.

[0004] The prior art CN_107474698 A discloses a kind of anticorrosion heat-dissipation powder coating and preparation method thereof, comprising the following steps: mixing, ultrasonic, melting, cooling, tabletting, powder grinding and sieving. The powder coating of the application not only prolongs the anticorrosion performance, but also has good heat dissipation performance and ultra-high dispersibility. However, in order to ensure the high dispersibility of the powder coating, dispersing agents and anti-settling agents need to be added during the mixing process, and the dispersing time is long. The dispersion process needs to be heated (50-65℃). After mixing, ultrasonic mixing is needed, and the frequency, power and other conditions of the ultrasonic need to be controlled. The ultrasonic time is long (30min). In addition, the temperature needs to be controlled during the melting process, which further increases the operation difficulty and energy consumption. Therefore, there is an urgent need for a powder coating preparation method with high dispersibility, high efficiency and low energy consumption. SUMMARY

[0005] The technical problem to be solved by the present application is that the existing powder coating preparation method cannot balance the dispersibility and preparation efficiency of the powder coating. The present application provides a method for preparing powder coating by using ultrasonic bonding technology. The present application uses the high-frequency vibration of ultrasonic energy to make the powder particles quickly and uniformly bond together in a short time, forming a uniform and dense powder coating with high dispersibility, high efficiency, low energy consumption and environmental protection.

[0006] The above object of the present application is achieved by the following technical solution: A method for preparing powder coating by using ultrasonic bonding technology, comprising the following steps: Step one: dispersing the to-be-bonded powder particles in the resin powder coating matrix to obtain a mixed powder; Step two: compressing the mixed powder; Step three: applying ultrasonic to the product obtained after step two and then cooling; the frequency of the ultrasonic is 10-70 kHz, the power of the ultrasonic is 200-4200 W, and the time of the ultrasonic is 0.1-30 s, Step four: crushing the product obtained after step three, and then sieving to obtain the powder coating.

[0007] Specifically, the median particle size of the to-be-bonded powder particles is 0.01-500 μm, and the median particle size of the resin powder coating matrix is 1-500 μm; preferably, the median particle size of the to-be-bonded powder particles is 1-300 μm, and the median particle size of the resin powder coating matrix is 10-500 μm.

[0008] Specifically, the to-be-bonded powder particles are selected from one or more of resin, pigment, filler, and additive; the resin is selected from any one of epoxy-polyester, polyester resin, epoxy resin, phenolic resin, polyurethane, fluorocarbon resin, polyethylene, polypropylene, acrylic resin, polyvinyl chloride, chlorinated polyether, polyphenylene sulfide, polyamide, polyethylene oxide, and cellulose resin; the pigment is selected from any one of organic pigment, inorganic pigment, or fluorescent pigment; the filler is selected from any one of metal oxide, hydroxide, or inorganic salt; and the additive is selected from any one of curing agent, degassing agent, matting agent, gloss agent, and leveling agent.

[0009] More specifically, the organic pigment is selected from any one of azo pigment, lake pigment, phthalocyanine blue pigment, quinacridone pigment, dioxazine pigment, orange pigment, or perylene red pigment; the inorganic pigment is selected from any one of metal powder aluminum powder, azurite pigment, mica powder, iron oxide green, iron oxide orange, or mineral pigment; and the fluorescent pigment is selected from any one of strontium aluminate, zinc sulfide, or calcium sulfide.

[0010] More specifically, the metal oxide is selected from any one of calcium oxide, aluminum oxide, magnesium oxide, barium oxide, iron oxide, or copper oxide; the hydroxide is selected from any one of sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, or strontium hydroxide; and the inorganic salt is selected from any one of metal salt or non-metal salt.

[0011] Specifically, the weight of the to-be-bonded powder particles accounts for 5-90% of the total weight of the to-be-bonded powder particles and the resin powder coating matrix.

[0012] Specifically, the resin powder coating matrix is selected from one or more of epoxy-polyester, polyester resin, epoxy resin, phenolic resin, polyurethane, polyimide, urea-formaldehyde resin, melamine-formaldehyde, PE-polyethylene, PP-polypropylene, PVC-polyvinyl chloride, PS-polystyrene, PA-polyamide, POM-polyoxymethylene, PC-polycarbonate, polyphenylene ether, polysulfone, rubber, acrylic resin, polyamide, polyester-TGIC.

[0013] Specifically, the resin powder coating matrix accounts for 10-98% of the total weight of the powder particles to be bonded and the resin powder coating matrix.

[0014] Specifically, the specific steps of the dispersion in step one are: mixing the powder particles to be bonded and the resin powder coating matrix, the mixing device is selected from any one of a mortar, an air flow crusher, a fluidized bed, an impeller stirrer, a ball mill or a rotary drum, and the mixing time is 10s-86400s; preferably, the mixing time is 30s-86400s.

[0015] Specifically, the compressed atmosphere in step two is selected from any one of air atmosphere, argon atmosphere, hydrogen atmosphere.

[0016] Specifically, the compression pressure in step two is 0.1-45MPa.

[0017] Specifically, the compression time in step two is 0.1-300s, preferably 0.1-60s, and specifically can be 0.1s, 0.5s, 0.6s, 1s, 5s, 15s, 30s, 45s, 60s.

[0018] Specifically, the frequency of the ultrasound in step three is 10kHz-70kHz, and specifically can be 10kHz, 15kHz, 20kHz, 25kHz, 30kHz, 40kHz, 50kHz, 60kHz, 70kHz, and preferably 15kHz.

[0019] Specifically, the power of the ultrasound in step three is 200-4200W, preferably 500-1500W, and specifically 500W, 650W, 780W, 800W, 850W, 900W, 950W, 1000W, 1080W, 1100W, 1150W, 1240W, 1400W, 1500W.

[0020] Specifically, the time of the ultrasonic in step three is 0.1-30s, preferably 0.1-10s, and specifically 0.1s, 0.5s, 0.7s, 1s, 1.1s, 1.2s, 1.4s, 1.5s, 2s, 2.4s, 3s, 3.4s, 8.8s, 10s.

[0021] Specifically, the time of the cooling in step three is 1-600s, preferably 1-300s, and specifically 8s, 10s, 12s, 13s, 16s, 20s, 22s, 30s, 50s, 60s, 180s, 300s.

[0022] Specifically, the ultrasonic device in step three is an ultrasonic bonding device, which comprises an ultrasonic vibration head or transducer for uniform vibration, and the material of the ultrasonic vibration head or transducer is one or more of aluminum alloy, hard alloy, tool steel, and ceramic material.

[0023] More specifically, the ultrasonic bonding device comprises a workbench for placing the to-be-bonded object, and the shape of the workbench is selected from one or more of a circle, a square, and a special shape; the special shape is selected from any one of a triangle, a heart shape, or a polygon.

[0024] More specifically, the type of the ultrasonic bonding device is selected from any one of a single fixed type, a handheld type, or a continuous operation type; when the type of the ultrasonic bonding device is the single fixed type or the handheld type, the area of the workbench of the ultrasonic bonding device is 0.01-10m 2 ; when the type of the ultrasonic bonding device is the continuous operation type, the width of the workbench of the ultrasonic bonding device is 0.01-10m.

[0025] Preferably, the mesh size of the sieve in step four is 50-500 mesh, and specifically 50 mesh, 150 mesh, 100 mesh, 200 mesh, 300 mesh, 400 mesh, or 500 mesh.

[0026] The application also protects the use of the above-mentioned method for preparing powder coatings by ultrasonic bonding technology in the field of powder coating or particle homogenization technology.

[0027] Compared with the prior art, the application has the following beneficial effects: The application provides a method for preparing a powder coating by using an ultrasonic bonding technology, and the application transmits ultrasonic energy to powder particles, so that the powder particles generate high-frequency vibration under the action of the ultrasonic energy, instantaneous high temperature is generated through friction between the particles and the particles, the resin component on the surface of the coating particles is melted and sticky under the high temperature, and then the resin component is bonded with other powder particles, so that the powder particles are bonded in a short time, high-temperature heating is not needed, energy consumption is low, energy saving and environmental protection are achieved, the bonding efficiency is high, the effect is good, the high-frequency vibration of the ultrasonic energy can quickly and uniformly bond the powder particles together, the color difference of the embodiments is less than 2 (color difference value ΔE = 2, the smaller the color difference is, the better the bonding effect is), the required time is short, and the preparation efficiency is high. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The plate surface diagram of the samples of examples 1-3 and comparative examples 1-3.

[0029] Figure 2 The plate surface diagram of the samples of examples 1, 4, 5 and comparative examples 1, 4, 5.

[0030] Figure 3 The plate surface diagram of the samples of examples 5 and comparative examples 5, 7.

[0031] Figure 4 The plate surface diagram of the samples of examples 6 and comparative example 6.

[0032] Figure 5 The microscope diagram of examples 1 and comparative example 1 under 10 times magnification.

[0033] Figures 6-8 The schematic diagram of the ultrasonic operation mode of the ultrasonic workbench used in the examples in cooperation with the welding head in a vertical type, a roller type and a rolling type.

[0034] Figure 9 The schematic diagram of the ultrasonic bonding device used in the application, wherein 1 is an air pressure gauge and a pressure regulating valve; 2 is a welding head; 3 is a cylinder lowering speed adjusting valve; 4 is a lifting hand wheel; 5 is a horizontal adjusting screw and a fine adjusting screw; 6 is a machine body fixing handle; 7 is a start switch and an emergency stop button; 8 is an air cleaner; 9 is an ultrasonic generator; and 10 is a workbench. DETAILED DESCRIPTION

[0035] The application will be further described in combination with the specific embodiments, but the embodiments do not limit the application in any form. Unless otherwise specified, the raw materials used in the embodiments of the application are conventional purchased raw materials.

[0036] Example 1 An iron oxide green-epoxy-polyester hybrid powder coating is prepared by the following preparation method: (1) Take 38 g of epoxy-polyester powder coating particles (as base powder, with a median particle size of about 38 pm) and 2 g of green iron oxide particles (with a median particle size of about 10 pm), mix them in a mortar for 5 min, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 30 s at a pressure of 10 MPa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 900 W, and ultrasonically treat the mixed powder for 1 s, with a cooling process of 10 s; (3) Take out the treated powder to obtain a green iron oxide-epoxy-polyester hybrid powder coating with uniform bonding; (4) Crush the bonded hybrid powder coating, then sieve it using a 400-mesh sieve, and electrostatically spray the sieved powder.

[0037] Example 2 A green iron oxide-polyester-TGIC hybrid powder coating is prepared by the following preparation method: (1) Take 40 g of polyester-TGIC powder coating particles (as base powder, with a median particle size of about 52 pm) and 10 g of green iron oxide particles (with a median particle size of about 10 pm), mix them in a mortar for 5 min, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 30 s at a pressure of 10 MPa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 1500 W, and ultrasonically treat the mixed powder for 1.5 s, with a cooling process of 30 s; (3) Take out the treated powder to obtain a green iron oxide-polyester-TGIC hybrid powder coating with uniform bonding; (4) Crush the bonded hybrid powder coating, then sieve it using a 400-mesh sieve, and electrostatically spray the sieved powder.

[0038] Example 3 A green iron oxide-epoxy resin hybrid powder coating is prepared by the following preparation method: (1) Take 47.5 g of epoxy resin powder coating particles (as base powder, with a median particle size of about 74 pm) and 2.5 g of green iron oxide particles (with a median particle size of about 10 pm), mix them in a mortar for 5 min, and then place them in an ultrasonic bonding device; (3) Take out the treated powder to obtain a green iron oxide-epoxy resin mixed powder coating with uniform bonding; (4) Crush the mixed powder coating with uniform bonding, then sieve it through a 400-mesh screen, and electrostatically spray the sieved powder.

[0039] Example 4 A mineral azurite-epoxy-polyester mixed powder coating is prepared by the following preparation method: (1) Take 9 g of epoxy-polyester powder coating particles (as a base powder, with a median particle size of about 38 µm) and 1 g of azurite pigment (with a median particle size of about 15 µm), mix them in an air jet mill for 10 min, and then place them in an ultrasonic bonding device; (2) Under the protection of an argon atmosphere, slightly compress the mixed powder for 45 s at a pressure of 15 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 1000 W, and ultrasonically treat the mixed powder for 0.7 s, and cool for 12 s; (3) Take out the treated powder to obtain an azurite-epoxy-polyester mixed powder coating with uniform bonding; (4) Crush the mixed powder coating with uniform bonding, then sieve it through a 300-mesh screen, and electrostatically spray the sieved powder.

[0040] Example 5 An iron oxide orange-epoxy-polyester mixed powder coating is prepared by the following preparation method: (1) Take 7 g of epoxy-polyester powder coating particles (as a base powder, with a median particle size of about 38 µm) and 3 g of iron oxide orange pigment (with a median particle size of about 20 µm), mix them in a mortar for 10 min, and then place them in an ultrasonic bonding device; (2) Under the protection of an air atmosphere, slightly compress the mixed powder for 15 s at a pressure of 10 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 1400 W, and ultrasonically treat the mixed powder for 2 s, and cool for 10 s; (3) Take out the treated powder to obtain an iron oxide orange-epoxy-polyester mixed powder coating with uniform bonding; (4) Crush the mixed powder coating with uniform bonding, then sieve it through a 200-mesh screen, and electrostatically spray the sieved powder.

[0041] Example 6 A mica powder-epoxy-polyester mixed powder coating is prepared by the following preparation method: (1) Take 24.5 g of epoxy-polyester powder coating particles (as base powder, with a median particle size of about 38 µm) and 0.5 g of mica powder (with a median particle size of about 6 µm), mix them in a fluidized bed for 30 s, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of a hydrogen atmosphere for 60 s at a pressure of 20 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 950 W, and ultrasonically treat the mixed powder for 1.2 s, and then cool for 20 s; (3) Take out the treated powder to obtain a uniformly bonded mica powder-epoxy-polyester hybrid powder coating; (4) Crush the bonded hybrid powder coating, then sieve it using a 500-mesh sieve, and then electrostatically spray the sieved powder.

[0042] Example 7 An acrylic resin-epoxy-polyester hybrid powder coating was prepared by the following preparation method: (1) Take 30 g of epoxy-polyester powder coating particles (as base powder, with a median particle size of about 100 µm) and 30 g of acrylic resin (with a median particle size of about 36 µm), mix them in a mortar for 5 min, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 5 s at a pressure of 10 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 800 W, and ultrasonically treat the mixed powder for 1.5 s, and then cool for 22 s; (3) Take out the treated powder to obtain a uniformly bonded acrylic resin-epoxy-polyester hybrid powder coating; (4) Crush the bonded hybrid powder coating, then sieve it using a 400-mesh sieve, and then electrostatically spray the sieved powder.

[0043] Example 8 A long-afterglow strontium aluminate-acrylic resin hybrid powder coating was prepared by the following preparation method: (1) Take 9 g of acrylic resin powder coating particles (as base powder, with a median particle size of about 200 µm) and 1 g of long-afterglow strontium aluminate (with a median particle size of about 60 µm), mix them in an impeller stirrer for 30 s, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of a hydrogen atmosphere for 0.6 s at a pressure of 8 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 1000 W, and ultrasonically treat the mixed powder for 0.5 s, and then cool for 8 s; (3) Take out the treated powder to obtain a long afterglow strontium aluminate-acrylic resin hybrid powder coating with uniform bonding; (4) Crush the bonded hybrid powder coating, then sieve it using a 100-mesh screen, and electrostatically spray the sieved powder.

[0044] Example 9 A lithium hydroxide-acrylic resin hybrid powder coating is prepared by the following preparation method: (1) Take 19 g of acrylic resin powder coating particles (as a base powder, with a median particle size of about 80 µm) and 1 g of lithium hydroxide (with a median particle size of about 38 µm), mix them in a ball mill for 1 h, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 0.1 s at a pressure of 5 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 850 W, and ultrasonically treat the mixed powder for 0.1 s, with a cooling treatment of 12 s; (3) Take out the treated powder to obtain a lithium hydroxide-acrylic resin hybrid powder coating with uniform bonding; (4) Crush the bonded hybrid powder coating, then sieve it using a 200-mesh screen, and electrostatically spray the sieved powder.

[0045] Example 10 A sodium chloride-polyamide resin hybrid powder coating is prepared by the following preparation method: (1) Take 22 g of polyamide resin powder coating particles (as a base powder, with a median particle size of about 120 µm) and 3 g of sodium chloride (with a median particle size of about 60 µm), mix them in an impeller stirrer for 20 min, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 60 s at a pressure of 45 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 1150 W, and ultrasonically treat the mixed powder for 1.1 s, with a cooling treatment of 16 s; (3) Take out the treated powder to obtain a sodium chloride-polyamide resin hybrid powder coating with uniform bonding; (4) Crush the bonded hybrid powder coating, then sieve it using a 300-mesh screen, and electrostatically spray the sieved powder.

[0046] Example 11 A phthalocyanine blue pigment-epoxy resin hybrid powder coating is prepared by the following preparation method: (1) 18 g of epoxy resin powder coating particles (as base powder, median particle size about 85 pm) and 2 g of phthalocyanine blue pigment (median particle size about 40 pm) were weighed and mixed in a drum for 2 min, and then placed in an ultrasonic bonding device; (2) The mixed powder was slightly compressed under the protection of air atmosphere for 5 s at a pressure of 25 MPa; the ultrasonic bonding device was started, the ultrasonic frequency was set to 15 kHz, the power was set to 780 W, and the mixed powder was ultrasonically treated for 1.4 s, and cooled for 10 s; (3) The treated powder was taken out to obtain a phthalocyanine blue pigment-epoxy resin mixed powder coating with uniform bonding; (4) The bonded mixed powder coating was crushed, then sieved using a 50 mesh sieve, and the sieved powder was electrostatically sprayed.

[0047] Example 12 A phthalocyanine blue pigment-urea-formaldehyde resin mixed powder coating was prepared by the following preparation method: (1) 18 g of urea-formaldehyde resin powder coating particles (as base powder, median particle size about 68 pm) and 2 g of phthalocyanine blue pigment (median particle size about 40 pm) were weighed and mixed in a mortar for 30 min, and then placed in an ultrasonic bonding device; (2) The mixed powder was slightly compressed under the protection of air atmosphere for 0.1 s at a pressure of 0.1 MPa; the ultrasonic bonding device was started, the ultrasonic frequency was set to 15 kHz, the power was set to 500 W, and the mixed powder was ultrasonically treated for 1 s, and cooled for 13 s; (3) The treated powder was taken out to obtain a phthalocyanine blue pigment-urea-formaldehyde resin mixed powder coating with uniform bonding; (4) The bonded mixed powder coating was crushed, then sieved using a 150 mesh sieve, and the sieved powder was electrostatically sprayed.

[0048] Example 13 A phthalocyanine blue pigment-polyamide resin mixed powder coating was prepared by the following preparation method: (1) 118 g of polyamide resin powder coating particles (as base powder, median particle size about 60 pm) and 42 g of phthalocyanine blue pigment (median particle size about 40 pm) were weighed and mixed in a mortar for 30 min, and then placed in an ultrasonic bonding device; (2) The mixed powder was slightly compressed under the protection of air atmosphere for 1 s at a pressure of 1 MPa; the ultrasonic bonding device was started, the ultrasonic frequency was set to 15 kHz, the power was set to 1240 W, and the mixed powder was ultrasonically treated for 2.4 s, and cooled for 180 s; (3) Take out the treated powder to obtain a phthalocyanine blue pigment-polyamide resin mixed powder coating with uniform bonding; (4) Crush the mixed powder coating with uniform bonding, then sieve it through a 400-mesh screen, and electrostatically spray the sieved powder.

[0049] Example 14 A copper oxide-polyamide resin mixed powder coating is prepared by the following preparation method: (1) Take 27 g of polyamide resin powder coating particles (as a base powder, with a median particle size of about 10 µm) and 3 g of copper oxide (with a median particle size of about 1 µm), mix them in a mortar for 10 min, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 0.6 s at a pressure of 12 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 1080 W, and ultrasonically treat the mixed powder for 3 s, with a cooling treatment for 30 s; (3) Take out the treated powder to obtain a copper oxide-polyamide resin mixed powder coating with uniform bonding; (4) Crush the mixed powder coating with uniform bonding, then sieve it through a 500-mesh screen, and electrostatically spray the sieved powder.

[0050] Example 15 A polyethylene-epoxy resin mixed powder coating is prepared by the following preparation method: (1) Take 25 g of epoxy resin powder coating particles (as a base powder, with a median particle size of about 85 µm) and 15 g of polyethylene (with a median particle size of about 40 µm), mix them in a impeller mixer for 5 min, and then place them in an ultrasonic bonding device; (2) Slightly compress the mixed powder under the protection of an air atmosphere for 15 s at a pressure of 16 Mpa; start the ultrasonic bonding device, set the ultrasonic frequency to 15 kHz and the power to 650 W, and ultrasonically treat the mixed powder for 3.4 s, with a cooling treatment for 30 s; (3) Take out the treated powder to obtain a polyethylene-epoxy resin mixed powder coating with uniform bonding; (4) Crush the mixed powder coating with uniform bonding, then sieve it through a 300-mesh screen, and electrostatically spray the sieved powder.

[0051] Example 16 A calcium carbonate-epoxy resin mixed powder coating is prepared by the following preparation method: (1) 37 g of epoxy resin powder coating particles (as a base powder, with a median particle size of about 500 pm) and 3 g of calcium carbonate (with a median particle size of about 300 pm) were weighed out, mixed in a ball mill for 24 h, and then placed in an ultrasonic bonding device; (2) The mixed powder was lightly compressed for 15 s under the protection of an air atmosphere, at a pressure of 20 MPa; the ultrasonic bonding device was started, the ultrasonic frequency was set to 15 kHz, the power was set to 1500 W, and the mixed powder was subjected to ultrasonication for 10 s, with a cooling process of 300 s; (3) The treated powder was removed, and a uniformly bonded calcium carbonate-epoxy resin hybrid powder coating was obtained; (4) The bonded hybrid powder coating was crushed, then sieved using a 100-mesh sieve, and the sieved powder was electrostatically sprayed.

[0052] Example 17 A polyethylene oxide-acrylic resin hybrid powder coating was prepared by the following preparation method: (1) 2 g of acrylic resin powder coating particles (as a base powder, with a median particle size of about 400 pm) and 18 g of polyethylene oxide (with a median particle size of about 150 pm) were weighed out, mixed in a ball mill for 12 h, and then placed in an ultrasonic bonding device; (2) The mixed powder was lightly compressed for 0.5 s under the protection of an air atmosphere, at a pressure of 5 MPa; the ultrasonic bonding device was started, the ultrasonic frequency was set to 15 kHz, the power was set to 1400 W, and the mixed powder was subjected to ultrasonication for 8.8 s, with a cooling process of 60 s; (3) The treated powder was removed, and a uniformly bonded polyethylene oxide-acrylic resin hybrid powder coating was obtained; (4) The bonded hybrid powder coating was crushed, then sieved using a 500-mesh sieve, and the sieved powder was electrostatically sprayed.

[0053] Comparative Example 1 An iron oxide green-epoxy-polyester hybrid powder coating was prepared by the following preparation method: 19 g of epoxy-polyester powder coating particles (as a base powder, with a median particle size of about 38 pm) and 1 g of iron oxide green particles (with a median particle size of about 10 pm) were weighed out, mixed in a mortar for 5 min, and electrostatically sprayed, and a coating film was obtained after curing.

[0054] Comparative Example 2 A green iron oxide-polyester-TGIC hybrid powder paint is prepared by the following preparation method: 4 g of polyester-TGIC powder paint particles (as a base powder, with a median particle size of about 52 µm) and 1 g of green iron oxide particles (with a median particle size of about 10 µm) are weighed out, mixed in a mortar for 5 min, electrostatically sprayed, and the coating film obtained after curing.

[0055] Comparative Example 3 A green iron oxide-epoxy hybrid powder paint is prepared by the following preparation method: 19 g of epoxy powder paint particles (as a base powder, with a median particle size of about 74 µm) and 1 g of green iron oxide particles (with a median particle size of about 10 µm) are weighed out, mixed in a mortar for 5 min, electrostatically sprayed, and the coating film obtained after curing.

[0056] Comparative Example 4 A mineral azurite-epoxy-polyester hybrid powder paint is prepared by the following preparation method: 9 g of epoxy-polyester powder paint particles (as a base powder, with a median particle size of about 38 µm) and 1 g of azurite pigment (with a median particle size of about 15 µm) are weighed out, mixed in an air jet mill for 10 min, electrostatically sprayed, and the coating film obtained after curing.

[0057] Comparative Example 5 An orange-red-epoxy-polyester hybrid powder paint is prepared by the following preparation method: 7 g of epoxy-polyester powder paint particles (as a base powder, with a median particle size of about 38 µm) and 3 g of orange-red pigment (with a median particle size of about 20 µm) are weighed out, mixed in a mortar for 10 min, electrostatically sprayed, and the coating film obtained after curing.

[0058] Comparative Example 6 A mica powder-epoxy-polyester hybrid powder paint is prepared by the following preparation method: 24.5 g of epoxy-polyester powder paint particles (as a base powder, with a median particle size of about 38 µm) and 0.5 g of mica powder (with a median particle size of about 6 µm) are weighed out, mixed in a fluidized bed for 30 s, electrostatically sprayed, and the coating film obtained after curing.

[0059] Comparative Example 7 A pressure-bonded green iron oxide-epoxy-polyester hybrid powder paint is prepared by the following preparation method: 7 g of epoxy-polyester powder paint particles (as a base powder, with a median particle size of about 38 µm) and 3 g of green iron oxide pigment (with a median particle size of about 20 µm) are weighed out, mixed in a mortar for 10 min, pressure-bonded for 2 min, demolded for 1 min after the bonding is complete, removed, and pulverized, then sieved using a 200-mesh sieve, and the sieved powder is electrostatically sprayed, and the coating film obtained after curing.

[0060] Comparative Example 8 An acrylic resin-epoxy-polyester hybrid powder coating was prepared by the following preparation method: 15 g of epoxy-polyester powder coating particles (as a base powder, median particle diameter of about 100 µm) and 15 g of acrylic resin (median particle diameter of about 36 µm) were weighed out, mixed in a mortar for 5 min, electrostatically sprayed, and a coating film was obtained after curing.

[0061] Comparative Example 9 A long-persistence strontium aluminate-acrylic resin hybrid powder coating was prepared by the following preparation method: 9 g of acrylic resin powder coating particles (as a base powder, median particle diameter of about 200 µm) and 1 g of long-persistence strontium aluminate (median particle diameter of about 60 µm) were weighed out, mixed in a propeller stirrer for 30 s, electrostatically sprayed, and a coating film was obtained after curing.

[0062] Comparative Example 10 A lithium hydroxide-acrylic resin hybrid powder coating was prepared by the following preparation method: 19 g of acrylic resin powder coating particles (as a base powder, median particle diameter of about 80 µm) and 1 g of lithium hydroxide (median particle diameter of about 38 µm) were weighed out, mixed in a ball mill for 1 h, electrostatically sprayed, and a coating film was obtained after curing.

[0063] Comparative Example 11 A sodium chloride-polyamide resin hybrid powder coating was prepared by the following preparation method: 22 g of polyamide resin powder coating particles (as a base powder, median particle diameter of about 120 µm) and 3 g of sodium chloride (median particle diameter of about 60 µm) were weighed out, mixed in a propeller stirrer for 20 min, electrostatically sprayed, and a coating film was obtained after curing.

[0064] Comparative Example 12 A phthalocyanine blue pigment-epoxy resin hybrid powder coating was prepared by the following preparation method: 18 g of epoxy resin powder coating particles (as a base powder, median particle diameter of about 85 µm) and 2 g of phthalocyanine blue pigment (median particle diameter of about 40 µm) were weighed out, mixed in a drum for 2 min, electrostatically sprayed, and a coating film was obtained after curing.

[0065] Comparative Example 13 A phthalocyanine blue pigment-urea-formaldehyde resin hybrid powder coating was prepared by the following preparation method: 18 g of urea-formaldehyde resin powder coating particles (as a base powder, median particle diameter of about 68 µm) and 2 g of phthalocyanine blue pigment (median particle diameter of about 40 µm) were weighed out, mixed in a mortar for 30 min, electrostatically sprayed, and a coating film was obtained after curing.

[0066] Comparative Example 14 A phthalocyanine blue pigment-polyamide resin hybrid powder paint is prepared by the following preparation method: 29.5 g of polyamide resin powder paint particles (as a base powder, median particle diameter of about 60 µm) and 10.5 g of phthalocyanine blue pigment (median particle diameter of about 40 µm) are weighed out, mixed in a mortar for 30 min, electrostatically sprayed, and a coating film is obtained after curing.

[0067] Comparative Example 15 A copper oxide-polyamide resin hybrid powder paint is prepared by the following preparation method: 27 g of polyamide resin powder paint particles (as a base powder, median particle diameter of about 10 µm) and 3 g of copper oxide (median particle diameter of about 1 µm) are weighed out, mixed in a mortar for 10 min, electrostatically sprayed, and a coating film is obtained after curing.

[0068] Comparative Example 16 A polyethylene-epoxy resin hybrid powder paint is prepared by the following preparation method: 25 g of epoxy resin powder paint particles (as a base powder, median particle diameter of about 85 µm) and 15 g of polyethylene (median particle diameter of about 40 µm) are weighed out, mixed in a propeller stirrer for 5 min, electrostatically sprayed, and a coating film is obtained after curing.

[0069] Comparative Example 17 A calcium carbonate-epoxy resin hybrid powder paint is prepared by the following preparation method: 37 g of epoxy resin powder paint particles (as a base powder, median particle diameter of about 500 µm) and 3 g of calcium carbonate (median particle diameter of about 300 µm) are weighed out, mixed in a ball mill for 24 h, electrostatically sprayed, and a coating film is obtained after curing.

[0070] Comparative Example 18 A polyethylene oxide-acrylic resin hybrid powder paint is prepared by the following preparation method: 2 g of acrylic resin powder paint particles (as a base powder, median particle diameter of about 400 µm) and 18 g of polyethylene oxide (median particle diameter of about 150 µm) are weighed out, mixed in a ball mill for 12 h, electrostatically sprayed, and a coating film is obtained after curing.

[0071] Result detection The mixed powder coating prepared from Examples 1-17 and Comparative Examples 1-18 was sprayed on an aluminum plate (1060) by electrostatic spraying method at a voltage of 55 kV, cured at 200 DEG C for 10 min, and three parallel experiments were performed. Eight points were randomly selected for color difference test in each experiment, the first point was compared with the rest of the points in terms of color difference. Color difference refers to the difference in color perception between two samples, which includes three aspects of lightness difference, chroma difference and hue difference. Color difference value refers to the difference value of two colors calculated by color difference formula after measurement by a colorimeter. The difference between colors is represented by DE or delta E. The standard value of color difference is set as delta E = 2. The smaller the color difference, the more uniform the color distribution, and the better the bonding effect.

[0072] The mixed powder coating prepared from Example 5 and Comparative Example 7 was subjected to roughness test under the condition that the film thickness difference was controlled within ±5 microns.

[0073] From the analysis results, the color difference delta E = 2. The smaller the color difference, the more uniform the color distribution, and the better the bonding effect. As shown in Table 1, the color difference of Examples 1-17 is less than 2, while as shown in Table 2, the color difference of Comparative Examples 1-6 and 8-18 is greater than 2. Therefore, the ultrasonic vibration makes the molecular chains in the particles intertangle and interweave, and finally realizes the rapid and uniform bonding of the powder particles. As shown in Tables 1-4, the ultrasonic bonding of Example 5 and the pressure bonding of Comparative Example 7 are compared. The color difference value and roughness are both small under the condition that the film thickness is similar. Therefore, ultrasonic bonding can achieve the same effect as pressure bonding, and the time is shorter and the efficiency is higher. Figures 1-4 The sample plate surface graph can also be observed. It can be seen that the color of the coating sprayed after simple mixing is not uniform, while the color of the coating after bonding is more uniform. Figure 5 It can be seen that the plate surface of Comparative Example 1 is not uniform, and there is color deposition. Example 1 is relatively better, which shows that the bonding effect of the bonding method of the present application is excellent.

[0074] Table 1 Color difference data of Examples 1-17

[0075] Table 2 Color difference data of Comparative Examples 1-18

[0076] The above examples do not limit the equipment parameters and operating parameters of the present application, which are further described as follows: In the examples of the present application, a drum or a stirrer is used to move the powder, and other forms can also be used to move the powder. The size of the ultrasonic bonding device in the examples of the present application can be varied. The ultrasonic bonding frequency and time in the present application can be adjusted according to the glass transition temperature of the powder coating base powder and various resins.

[0077] Table 3 Example 5 and Comparative Example 7 film thickness data

[0078] Table 4 Example 5 and Comparative Example 7 roughness data

[0079] Obviously, the above-mentioned embodiments of the present application are only examples for clearly explaining the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to enumerate all the embodiments. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method for producing a powder coating by means of ultrasonic bonding technology, characterized in that The method comprises the following steps: Step one: dispersing the to-be-bonded powder particles in a resin powder coating matrix to obtain a mixed powder; Step two: compressing the mixed powder; Step three: applying ultrasonic waves to the product obtained in step two and then cooling it; the frequency of the ultrasonic waves is 10-70 kHz, the power of the ultrasonic waves is 200-4200 W, and the time of the ultrasonic waves is 0.1-30 s; Step four: crushing the product obtained in step three and sieving it to obtain a powder coating.

2. The method for producing a powder paint using an ultrasonic bonding technique according to claim 1, wherein The to-be-bonded powder particles in step one have a median particle size of 0.01-500 µm, and the resin powder coating matrix has a median particle size of 1-500 µm.

3. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The to-be-bonded powder particles are selected from one or more of resins, pigments, fillers, and additives; preferably, the resins are selected from any one of epoxy-polyester, polyester resin, epoxy resin, phenolic resin, polyurethane, fluorocarbon resin, polyethylene, polypropylene, acrylic resin, polyvinyl chloride, chlorinated polyether, polyphenylene sulfide, polyamide, polyethylene oxide, and cellulose resin; the pigments are selected from any one of organic pigments, inorganic pigments, or fluorescent pigments; the fillers are selected from any one of metal oxides, hydroxides, or inorganic salts; and the additives are selected from any one of curing agents, degassing agents, matting agents, gloss enhancers, and leveling agents.

4. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The resin powder coating matrix in step one is selected from one or more of epoxy-polyester, polyester resin, epoxy resin, phenolic resin, polyurethane, polyimide, urea-formaldehyde resin, melamine-formaldehyde, PE-polyethylene, PP-polypropylene, PVC-polyvinyl chloride, PS-polystyrene, PA-polyamide, POM-polyoxymethylene, PC-polycarbonate, polyphenylene ether, polysulfone, rubber, acrylic resin, polyamide, and polyester-TGIC.

5. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The dispersion in step one is specifically carried out by mixing the to-be-bonded powder particles and the resin powder coating matrix, and the mixing device is selected from any one of a mortar, an air flow crusher, a fluidized bed, an impeller stirrer, a ball mill, or a rotary drum; the mixing time is 10 s-86400 s.

6. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The weight of the to-be-bonded powder particles accounts for 5-90% of the total weight of the to-be-bonded powder particles and the resin powder coating matrix.

7. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The weight of the resin powder coating matrix accounts for 10-98% of the total weight of the to-be-bonded powder particles and the resin powder coating matrix.

8. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The compression in step two is carried out at a pressure of 0.1-45 MPa for 0.1-300 s; and the cooling in step three is carried out for 1-600 s.

9. The method of claim 1, wherein the ultrasonic bonding technique is performed at a frequency of 20 kHz to 40 kHz. The sieving in step four is carried out using a sieve mesh of 50-500 mesh.

10. Use of the method for preparing a powder coating by ultrasonic bonding technology according to any one of claims 1-9 in powder coating preparation or particle homogenization.

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