Powder coating composition

Abstract

The present invention relates to a powder coating composition comprising an epoxy resin, a silicone resin, and a phenolic resin. It also relates to a coated substrate comprising a coating, wherein the coating is deposited from a powder coating composition comprising an epoxy resin, a silicone resin, and a phenolic resin.

Description

Technical Field

[0001] The present invention relates to the field of solid coatings, and particularly to a powder coating composition that is particularly suitable for substrates of new energy vehicles. Background Art

[0002] In recent years, new energy vehicles have developed rapidly, and the demand for coatings suitable for new energy vehicles in the market has also been continuously increasing. Compared with traditional vehicle coatings, new energy vehicle coatings have higher requirements for high temperature resistance, electrolyte resistance, and insulation to reduce the risk of spontaneous combustion of vehicles due to thermal runaway or battery problems.

[0003] Therefore, it is desirable to develop a powder coating composition with excellent high temperature resistance, electrolyte resistance, and electrical insulation properties, which is suitable for application on substrates of new energy vehicles, including vehicle exterior substrates, vehicle interiors, battery components, and so on. Summary of the Invention

[0004] In view of the above technical problems, the inventors of the present invention have conducted extensive research and developed a powder coating composition with excellent mechanical properties, especially in terms of high temperature resistance, electrolyte resistance, and electrical insulation properties, and thus is suitable for substrates of new energy vehicles.

[0005] In one aspect, the present invention provides a powder coating composition comprising an epoxy resin and a phenolic resin.

[0006] In another aspect, the present invention provides a coated substrate comprising a coating, wherein the coating is deposited from a powder coating composition comprising an epoxy resin and a phenolic resin. Detailed Description

[0007] Except as in the examples or otherwise expressly stated, all numerical values representing the amounts of components, reaction conditions, etc. used in the specification and claims should be understood to be subject to variation in all cases by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and claims are approximations that may vary depending upon the properties desired to be obtained by the present invention. At the very least, and not as a limitation on the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding techniques.

[0008] Although the broad numerical ranges and parameters set forth for the present invention are approximations, the numerical values set forth in the specific examples are recorded as accurately as possible. However, any numerical value inherently has a certain error, which is an inevitable result of the standard deviation in the corresponding measurement method.

[0009] In addition, it should be understood that any numerical range described herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the stated minimum value of 1 and the stated maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0010] In this application, unless otherwise expressly stated, the use of the singular includes the plural and the plural includes the singular. Further, in this application, unless otherwise expressly stated, the use of "or" means "and / or", even though in some instances "and / or" may be expressly used. Further, in this application, unless otherwise expressly stated, the use of "a" means "at least one". For example, "a" coating material, etc. refers to any one or more of such articles. And as will be recognized by those skilled in the art, the features of one embodiment may be used with other embodiments, even though not expressly stated herein.

[0011] As used herein, the term "powder coating composition" refers to a solid powder coating composition composed of components such as resin, curing agent, pigment, filler, and / or additive. The "powder" refers to a substance that is dry at room temperature (i.e., 20 to 30 °C) and atmospheric pressure and is in a fine, loose particulate state. Generally, the maximum size of individual particles in the powder coating composition does not exceed 200 μm, and the particle size can be obtained by sieving. Generally, based on the total weight of the powder coating composition, the maximum residual level of VOC (volatile organic compound) in the powder coating composition is not greater than 0.3 wt%. As described herein, the "VOC (volatile organic compound)" refers to any organic compound having a boiling point less than or equal to 250 °C (482 °F) measured at a standard atmospheric pressure of 101.3 kPa.

[0012] The powder coating composition according to the present invention can be thermally cured. As used herein, the term "curing" means that the components in the powder coating composition become "fixed", i.e., an irreversible crosslinked network is formed. In the powder coating composition of the present invention, the groups contained in the resin can react with the curing agent or other groups contained in the resin to form a crosslinked network. Suitably, the powder coating composition according to the present invention can be cured at 180 - 250 °C for 10 - 30 min. The said "curing" means sufficient curing, which means that after baking at the curing temperature for a certain time, such as 180 °C for 30 min (starting to count 10 min after the substrate surface temperature reaches 180 °C), the coating film formed by the powder coating composition has a MEK double rub value of more than 50 times, suitably more than 70 times. For example, when the powder coating composition does not contain silicone resin, the powder coating composition according to the present invention can be cured at 180 - 230 °C for 10 - 30 min, such as 180 °C for 30 min. For example, when the powder coating composition does not contain silicone resin, the powder coating composition according to the present invention can be cured at 230 - 250 °C for 10 - 30 min, such as 230 °C for 30 min.

[0013] The powder coating composition according to the present invention can have a gelling time at 200 °C of 90 - 600 s. The said "gelling time" means the time required for the powder coating composition to change from a molten state to a non-flowable state at a given temperature, i.e., 200 °C. In this article, the said "gelling time" can be measured according to the ISO8130-6 standard. This gelling time range enables the powder coating composition to have excellent application performance at high film thicknesses.

[0014] The coating formed by the powder coating composition according to the present invention can have a cured film thickness of at least 120 μm, suitably at least 150 μm, such as at least 200 μm. The said "cured film thickness" means the thickness of the coating formed by the powder coating composition after complete curing. However, the cured film thickness of conventional high-temperature resistant powder coatings is in the range of 40 - 60 μm, because too high a cured film thickness easily causes problems such as cracking, blistering and peeling of the coating film under high-temperature conditions. Therefore, the powder coating composition according to the present invention solves the problems of cracking, blistering and peeling of high cured film thicknesses through formulation design, enabling the cured film thickness to be increased several times, even reaching more than 200 μm.

[0015] The coating formed by the powder coating composition according to the present invention can have a cured film Tg of at least 100 °C, such as a cured film Tg of 100 - 120 °C. The specific test method is as described below. This cured film Tg range enables the coating formed by the powder coating composition to have a dense crosslinking density, improving the electrolyte resistance.

[0016] The cured coating formed from the powder coating composition according to the present invention has high temperature resistance. Herein, the high temperature resistance of the coating is evaluated by testing the weight loss of the cured coating formed from the powder coating composition under high temperature conditions (i.e., (weight before high temperature - weight after high temperature) / weight before high temperature). The weight loss value can be tested using a TGA instrument through the following steps: 1. Equilibrate at 50°C; 2. Heat up to 350°C at a heating rate of 10°C / min; 3. Keep at a constant temperature of 350°C for 30 min; 4. Read the data of the TGA instrument. The cured coating formed from the powder coating composition according to the present invention has a weight loss of less than 15 wt% after being heated at 350°C for 30 minutes. Suitably, the cured coating formed from the powder coating composition according to the present invention has a weight loss of less than 15 wt% after being heated at 360°C for 30 minutes, after being heated at 370°C for 30 minutes, and even after being heated at 380°C for 30 minutes.

[0017] The cured coating formed from the powder coating composition according to the present invention has electrical insulation properties and can still meet the electrical insulation withstand voltage requirements even after experiencing high temperature, electrolyte immersion, and aging. Herein, the electrical insulation performance of the coating is evaluated by performing a withstand voltage test on the cured coating formed from the powder coating composition after high temperature, electrolyte immersion, and double 85 aging. The specific test method is as described below. Suitably, the shear strength of the adhesive of the cured coating formed from the powder coating composition according to the present invention after 1000 h of double 85 aging test is at least 7 MPa, and the pull-off strength from the adhesive is at least 7 MPa, and the strength refers to the ASTM D1002 standard.

[0018] In one aspect, the powder coating composition according to the present invention comprises an epoxy resin and a phenolic resin. The epoxy groups in the epoxy resin can react with the phenolic hydroxyl groups in the phenolic resin. Suitably, the molar ratio of the epoxy groups in the epoxy resin to the phenolic hydroxyl groups in the phenolic resin can be 0.3 - 1.2:1. For example, the molar ratio of the epoxy groups in the epoxy resin to the phenolic hydroxyl groups in the phenolic resin can be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, or 1.1:1. Suitably, the weight ratio of the epoxy resin to the phenolic resin is 2 - 15:1.

[0019] The epoxy resin refers to a polymer containing more than two epoxy groups in the molecule. Suitably, the epoxy resin is solid at room temperature (e.g., 15 - 30 °C). Suitably, the epoxy resin may have an epoxy equivalent of 150 - 1000 g / eq, such as an epoxy equivalent of 600 - 1000 g / eq. The epoxy equivalent refers to the mass of the resin containing 1 mol of epoxy groups and can be determined by titration. Suitably, the softening point of the epoxy resin may be 65 - 120 °C. The softening point can be determined by the method of GB / T 12007.6 - 1989. For example, the softening point of the epoxy resin may be 70 °C, 80 °C, 90 °C, 100 °C, or 110 °C.

[0020] Based on the total weight of the powder coating composition, the epoxy resin may be at least 25 wt%, at least 30 wt%, at least 35 wt%, and / or at most 50 wt%, at most 45 wt%, at most 40 wt%. For example, based on the total weight of the powder coating composition, the epoxy resin may be 25 - 50 wt%, 30 - 45 wt%, 35 - 40 wt%, or within any range with the above values as endpoints.

[0021] The phenolic resin refers to a polymer obtained by condensation of raw materials containing phenols such as phenol and / or xylenol and aldehydes such as formaldehyde. Suitably, the phenolic resin may be obtained from raw materials containing phenol and formaldehyde. Suitably, the phenolic resin is solid at room temperature (e.g., 15 - 30 °C).

[0022] Suitably, the hydroxyl value of the phenolic resin may be 90 to 120 mg KOH / g. The hydroxyl value refers to the milligrams of potassium hydroxide (KOH) equivalent to the hydroxyl groups in 1 gram of the resin and can be determined by titration. For example, the hydroxyl value of the phenolic resin may be 100 mg KOH / g, or 110 mg KOH / g. Suitably, the softening point of the phenolic resin is 60 to 120 °C. The softening point can be determined by the method of GB / T 12007.6 - 1989. For example, the softening point of the phenolic resin is 70 °C, 80 °C, 90 °C, 100 °C, or 110 °C. Suitably, the Mw of the phenolic resin is 2500 to 5000. The Mw refers to the weight-average molecular weight and can be determined by gel permeation chromatography using appropriate standards such as polystyrene standards. For example, the Mw of the phenolic resin is 3000, 3500, 4000, or 4500.

[0023] Based on the total weight of the powder coating composition, the phenolic resin can be at least 1 wt%, at least 2 wt%, at least 3 wt%, and / or at most 10 wt%, at most 8 wt%, at most 5 wt%. For example, based on the total weight of the powder coating composition, the phenolic resin can be 1-10 wt%, 2-8 wt%, 3-5 wt%, or within any range with the above values as endpoints.

[0024] The powder coating composition according to the present invention may further include a silicone resin. The silicone resin refers to a thermosetting polysiloxane polymer having a highly cross-linked network structure. In the silicone resin, silicon-oxygen-silicon is the main chain, and silicon atoms are connected to organic groups. In the powder coating composition of the present invention, the addition of the silicone resin forms a silicon-O-phenyl structure in the coating, further improving the performance of the coating. Suitably, the weight ratio of the epoxy resin, the silicone resin, and the phenolic resin may be 3-10:1-12:1-6. Suitably, the epoxy resin, the silicone resin, and the phenolic resin may constitute 30-70 wt% of the total weight of the powder coating composition, for example 40-60 wt%. Suitably, the silicone resin is solid at room temperature (such as 15-30 °C). Suitably, the silicone resin contains hydroxyl groups.

[0025] Based on the total weight of the powder coating composition, the silicone resin can be at least 1 wt%, at least 5 wt%, at least 10 wt%, and / or at most 40 wt%, at most 30 wt%, at most 20 wt%. For example, based on the total weight of the powder coating composition, the silicone resin can be 1-40 wt%, 5-30 wt%, 10-20 wt%, or within any range with the above values as endpoints.

[0026] The powder coating composition according to the present invention may further include a curing agent. The curing agent can assist the cross-linking and curing of the above-mentioned epoxy resin, the above-mentioned phenolic resin, and optionally the above-mentioned silicone resin. Suitably, the curing agent may include a dicyandiamide-based curing agent and / or a phenolic curing agent. For example, the curing agent includes a phenolic curing agent. Suitably, the phenolic curing agent may have a phenolic hydroxyl equivalent of 200-300 g / eq. The phenolic hydroxyl equivalent refers to the mass of the curing agent containing 1 mol of phenolic hydroxyl groups and can be measured by titration. Suitably, the softening point of the phenolic curing agent may be 65-95 °C. The softening point can be measured by the method of GB / T 12007.6-1989. For example, the softening point of the phenolic curing agent may be 70 °C, 80 °C, or 90 °C. Based on the total weight of the powder coating composition, the curing agent can be 0-6 wt%.

[0027] The powder coating composition according to the present invention may further include pigments. The pigments can impart color and / or visual effects to the powder coating while improving the relevant mechanical properties of the powder coating. Suitably, the pigments may include inorganic pigments. For example, the inorganic pigments may include titanium dioxide, carbon black, copper chromite black, iron oxide red, and / or iron oxide yellow, etc. Based on the total weight of the powder coating composition, the pigments may be 3-20 wt%.

[0028] The powder coating composition according to the present invention may further include fillers. The fillers can be used to enhance the mechanical properties of the powder coating, such as abrasion resistance, corrosion resistance, stability, etc. Suitably, the fillers may include inorganic fillers. For example, the inorganic fillers may include mica, SiO2, glass fiber, anorthoclase, wollastonite, calcined kaolin, and / or barium sulfate. Based on the total weight of the powder coating composition, the inorganic fillers may be 20-60 wt%.

[0029] The powder coating composition according to the present invention may further include additives. Suitably, the additives include but are not limited to leveling agents, defoaming agents, adhesion improvers, flow aids, catalysts, antioxidants, antibacterial agents, flame retardants, etc. When in use, those skilled in the art can adjust the content of the additives according to actual needs. Generally, based on the total weight of the powder coating composition, the amount of each additive does not exceed 5 wt%.

[0030] The powder coating composition according to the present invention can be applied to a substrate by electrostatic spraying. Then, the powder coating composition according to the present invention can be cured at 180-250 °C for 10-30 min, such as 180 °C for 30 min, or 250 °C for 10 min. The coating formed by the powder coating composition according to the present invention can have a cured film thickness of at least 120 μm.

[0031] The powder coating composition according to the present invention can be applied to substrates such as metals and plastics. Suitably, the substrate is part of a new energy vehicle.

[0032] The powder coating composition according to the present invention can be applied to treated and / or coated substrates. The powder coating composition according to the present invention can be applied to untreated and / or uncoated substrates. The treatment may include pretreatment operations such as cleaning and sanding. Suitably, the substrate may include substrates of any shape.

[0033] In another aspect, the present invention provides a coated substrate including a coating, wherein the coating is deposited from a powder coating composition including an epoxy resin and a phenolic resin. Suitably, the powder coating composition further includes a silicone resin. For example, the powder coating composition is as described above.

[0034] Suitably, the coating has a cured film Tg of at least 100 °C. Suitably, the coating has a weight loss of less than 15 wt% after being heated at 350 °C for 30 minutes. Suitably, after 1000 h of double 85 aging test, the shear strength of the adhesive of the coating is at least 7 MPa, and the pull-out strength from the adhesive is at least 7 MPa, with the strength being referenced to ASTM D1002 standard.

[0035] Suitably, the substrate is part of a new energy vehicle.

[0036] Examples

[0037] The following examples are provided to further illustrate the present invention, but the present invention should not be considered limited to the details described in the examples. Unless otherwise specified, all parts and percentages in the following examples are by weight.

[0038] Examples 1 - 5

[0039] Prepare the powder coating composition according to the present invention using the components and contents listed in Table 1 below: After premixing each component in a premixer, melt and extrude it in an extruder at an extrusion temperature below 200 °C. The extruded material is cooled and pressed into sheet material on a cooling roll, crushed into small particle sheet material by a crusher on a pressing roll, and then ground into powder by a grinding machine, and sieved through a sieve to control the particle size suitable for construction (e.g., 35 - 45 μm) and fluidity.

[0040] Table 1. Powder coating compositions Ex1 - Ex5

[0041] / wt% Ex1 Ex2 Ex3 Ex4 Ex5 <![CDATA[Epoxy resin 1 > 40 40 42 36 30 <![CDATA[Phenolic resin 2 > 8 5 3 5 5 <![CDATA[Silicone resin 3 > 0 0 0 5 10 <![CDATA[Curing agent 4 > 2 5 5 4 5 <![CDATA[Black pigment 5 > 5 5 5 5 5 <![CDATA[Fiberglass 6 > 10 10 10 10 10 <![CDATA[Mica 7 > 5 5 5 5 5 <![CDATA[Wollastonite 8 > 22.85 22.85 22.85 22.85 22.85 <![CDATA[Leveling agent 9 > 1 1 1 1 1 <![CDATA[Defoamer 10 > 1 1 1 1 1 <![CDATA[Adhesion improver 11 > 5 5 5 5 5 <![CDATA[Flow aid 12 > 0.15 0.15 0.15 0.15 0.15 Total 100 100 100 100 100

[0042] 1. Solid at room temperature, epoxy equivalent 700 - 800 g / eq, softening point 90 - 98 °C;

[0043] 2. Solid at room temperature, phenolic resin is prepared from a raw material mixture containing phenol and formaldehyde, hydroxyl value 95 - 105 mg KOH / g, softening point 105 - 110 °C, Mw 3000 - 3500;

[0044] 3. Solid silicone resin containing hydroxyl groups;

[0045] 4. KD - 404J EPOXY RESIN;

[0046] 5. Shepherd Black 1;

[0047] 6. MICROGLAS 3082;

[0048] 7. Suzorite 325 (MICA);

[0049] 8. Nyad 400;

[0050] 9. PL-200;

[0051] 10. BENZOIN–MIWON;

[0052] 11. MA210 Adhesion Promoter; and

[0053] 12. AEROXIDE ALU C.

[0054] Comparative Examples 1-5

[0055] Prepare the powder coating compositions of the comparative examples using the components and contents listed in Table 2 below: After premixing each component well, melt and extrude it through an extruder. The extrusion temperature is below 200 °C. The extruded material is cooled and pressed into sheet materials on a cooling roll, crushed into small granular sheet materials by a crusher on a pressing roll, and then ground into powder by a grinding machine. The particle size (e.g., 35-45 μm) and fluidity suitable for construction are controlled by sieving through a sieve.

[0056] Table 2. Powder Coating Compositions CE1-CE5

[0057] / wt% CE1 CE2 CE3 CE4 CE5 <![CDATA[Epoxy resin 1 > 35 25 29 17 22 <![CDATA[Epoxy resin 2 > 0 0 0 5 5 <![CDATA[Phenolic resin 3 > 0 0 0 0 0 <![CDATA[Silicone resin 4 > 0 10 10 10 10 <![CDATA[Curing agent 5 > 15 15 11 18 13 <![CDATA[Black pigment 6 > 5 5 5 5 5 <![CDATA[Glass fiber 7 > 10 10 10 10 10 <![CDATA[mica 8 > 5 5 5 5 5 <![CDATA[Wollastonite 9 > 22.85 22.85 22.85 22.85 22.85 <![CDATA[Leveling agent 10 > 1 1 1 1 1 <![CDATA[Defoamer 11 > 1 1 1 1 1 <![CDATA[Adhesion improver 12 > 5 5 5 5 5 <![CDATA[Flow aid 13 > 0.15 0.15 0.15 0.15 0.15 Total 100 100 100 100 100

[0058] 1. Solid at room temperature, epoxy equivalent 700-800 g / eq, softening point 90-98 °C;

[0059] 2. Solid at room temperature, o-cresol novolac epoxy resin, epoxy equivalent 190-210 g / eq;

[0060] 3. Solid at room temperature, phenolic resin obtained by preparing from a raw material mixture containing phenol and formaldehyde, hydroxyl value 95-105 mg KOH / g, softening point 105-110 °C, Mw 3000-3500;

[0061] 4. Solid silicone resin containing hydroxyl groups;

[0062] 5. KD-404J EPOXY RESIN;

[0063] 6. Shepherd Black 1;

[0064] 7. MICROGLAS 3082;

[0065] 8. Suzorite 325 (MICA);

[0066] 9. Nyad 400;

[0067] 10. PL-200;

[0068] 11. BENZOIN–MIWON;

[0069] 12. MA210 Adhesion Promoter; and

[0070] 13. AEROXIDE ALU C.

[0071] Examples Ex1 to Ex5 and Comparative Examples CE1 to CE5 were electrostatically spray-coated on a substrate, which was 3003 aluminum plate with a size of 60 mm X 60 mm X 3 mm and pretreated by passivation treatment; then, the coating composition was cured under baking conditions, and the following performance tests were carried out on the cured coated substrate:

[0072] Gloss

[0073] According to the ISO 2813 standard, the surface gloss value of the coated substrate at a 60° angle was measured using a haze-gloss meter (Byk-Gardner).

[0074] Gel time

[0075] According to the ISO8130-6 standard, the gel time of the coating composition at 200 °C was measured.

[0076] Initial adhesion

[0077] According to the ASTM D3359 standard, the initial adhesion of the coated substrate was measured.

[0078] Tg of the cured film

[0079] The Tg of the cured film was measured using a TA differential thermal analyzer. The steps included: heating from room temperature to 100 °C at a heating rate of 20 °C / min; then holding at 100 °C for 5 min to eliminate the thermal history; cooling from 100 °C to room temperature at a cooling rate of 20 °C / min; heating from room temperature to 150 °C at a heating rate of 10 °C / min; and reading the values of the TA differential thermal analyzer.

[0080] High temperature resistance

[0081] The coated substrate was exposed to 350 °C * 30 min, 370 °C * 30 min, and 380 °C * 30 min, and then the appearance integrity of the coating film on the coated substrate was observed and the insulation of the coating film was tested.

[0082] Requirements:

[0083] 1. Coating film appearance: no bubbles, cracks, and peeling; and,

[0084] 2. The withstand voltage test meets AC 2600V for 60 seconds, and the leakage current does not exceed 1.0 mA.

[0085] Electrolyte resistance

[0086] Immerse the coated substrate in the electrolyte (including 30 - 40 wt% ethylene carbonate, 0 - 10 wt% propylene carbonate, 50 - 60 wt% ethyl methyl carbonate, 0 - 10 wt% dimethyl carbonate, 10 - 20 wt% lithium hexafluorophosphate) at room temperature (25 °C) for 7 days, and then test the insulation of the coating film.

[0087] Requirements:

[0088] 1. Coating film appearance: no bubbles, cracks, and peeling; and,

[0089] 2. The withstand voltage test meets AC 2600V for 60 seconds, and the leakage current does not exceed 1.0 mA.

[0090] Double 85 aging resistance test

[0091] In this article, the "double 85 aging resistance test" refers to placing the coating film at a temperature of 85 °C and a relative humidity of 85% for 1000 hours and then conducting performance tests to evaluate the aging resistance of the coating film. The specific test methods include:

[0092] 1. Place the coated substrate in a damp heat box at a temperature of 85 °C and a relative humidity of 85% for 1000 hours;

[0093] 2. Cover the surface of the coated substrate with conductive foam and test the insulation withstand voltage;

[0094] 3. Use the cross - cut method to test the adhesion;

[0095] 4. Apply structural adhesive on the coated substrate and test the shear pull - out strength according to the ASTM D1002 standard through a CMT4204 tensile machine.

[0096] Requirements:

[0097] 1. Coating film appearance: no blistering, cracking, peeling, and no serious discoloration;

[0098] 2. The withstand voltage test meets AC 2600V for 60 seconds, and the leakage current does not exceed 1.0 mA;

[0099] 3. Adhesion above 4B; and

[0100] 4. The shear strength with the structural adhesive is at least 7 MPa, and the pull - out strength is at least 7 MPa.

[0101] The test results of Examples Ex1 to Ex5 and Comparative Examples CE1 to CE5 are shown in Tables 3 and 4 below.

[0102] Table 3. Test Results of Examples Ex1 to Ex5

[0103]

[0104]

[0105] Table 4. Test Results of Comparative Examples CE1 to CE5

[0106]

[0107] As can be seen from the above, Examples Ex1 to Ex5 of the powder coating composition according to the present invention have high temperature resistance, electrolyte resistance, and can even pass the double 85 aging test; however, Comparative Examples CE1 to CE5 cannot satisfy the above properties simultaneously.

[0108] Although specific aspects of the present invention have been explained and described, it will be apparent to those skilled in the art that many other changes and modifications can be made without departing from the spirit and scope of the present invention. Accordingly, the appended claims are intended to cover all such changes and modifications that fall within the scope of the present invention.

Claims

1. A coated substrate comprising a coating, wherein the coating is deposited from a powder coating composition comprising an epoxy resin, a phenolic resin, a silicone resin, and an inorganic filler, wherein, The epoxy equivalent of the epoxy resin is 600 to 1000 g / eq and the softening point is 80 to 110 °C. The hydroxyl value of the phenolic resin is 90 to 110 mg KOH / g, the softening point is 100 to 120 °C, and the Mw is 3000 to 3500. The silicone resin contains hydroxyl groups. The inorganic filler includes mica, wollastonite, glass fiber, and / or SiO2. Wherein, the powder coating composition is cured at 230 - 250 °C, and the gelling time of the powder coating composition at 200 °C is 90 to 600 s. Wherein, the coating has a cured film thickness of at least 120 μm and a cured film Tg of at least 100 °C.

2. The coated substrate according to claim 1, wherein the weight loss of the coating after heating at 350 °C for 30 minutes is less than 15 wt%.

3. The coated substrate according to claim 1, wherein the shear strength of the coating with the adhesive is at least 7 MPa and the pull-out strength with the adhesive is at least 7 MPa after 1000 h of double 85 aging test, and the strength test refers to the ASTM D1002 standard.

4. The coated substrate according to claim 1, wherein the substrate is part of a new energy vehicle.

5. The coated substrate according to claim 1, wherein the coating contains a silicon-O-phenyl crosslinked structure.

6. The coated substrate according to claim 1, wherein the powder coating composition can be cured at 230 °C * 30 min.

7. The coated substrate according to claim 1, wherein the epoxy groups in the epoxy resin react with the phenolic hydroxyl groups in the phenolic resin.

8. The coated substrate according to claim 1, wherein the molar ratio of the epoxy groups in the epoxy resin to the phenolic hydroxyl groups in the phenolic resin is 0.3 - 1.2:

1.

9. The coated substrate according to claim 1, wherein the silicone resin content is 1 - 40 wt% of the total weight of the powder coating composition.

10. The coated substrate according to claim 1, wherein the epoxy resin, the silicone resin, and the phenolic resin constitute 30 - 70 wt% of the total weight of the powder coating composition.

11. The coated substrate according to claim 1, wherein the inorganic filler is 20 - 60 wt% of the total weight of the powder coating composition.

12. A powder coating composition comprising an epoxy resin, a phenolic resin, a silicone resin, and an inorganic filler, wherein, The epoxy equivalent of the epoxy resin is 600 to 1000 g / eq and the softening point is 80 to 110 °C. The hydroxyl value of the phenolic resin is 90 to 110 mg KOH / g, the softening point is 100 to 120 °C, and the Mw is 3000 to 3500. The silicone resin contains hydroxyl groups. The inorganic filler includes mica, wollastonite, glass fiber, and / or SiO2. Wherein, the powder coating composition is cured at 230 - 250 °C, and the gelling time of the powder coating composition at 200 °C is 90 to 600 s. Wherein, the powder coating composition forms a coating having a cured film thickness of at least 120 μm and a cured film Tg of at least 100 °C.

13. The powder coating composition according to claim 12, wherein epoxy groups in the epoxy resin react with phenolic hydroxyl groups in the phenolic resin.

14. The powder coating composition according to claim 12, wherein the molar ratio of epoxy groups in the epoxy resin to phenolic hydroxyl groups in the phenolic resin is 0.3 - 1.2:

1.

15. The powder coating composition according to claim 12, wherein the silicone resin content is 1 - 40 wt% of the total weight of the powder coating composition.

16. The powder coating composition according to claim 12, wherein the epoxy resin, the silicone resin and the phenolic resin constitute 30 - 70 wt% of the total weight of the powder coating composition.

17. The powder coating composition according to claim 12, wherein the powder coating composition forms a coating containing a silicon - O - phenyl cross - linked structure.

18. The powder coating composition according to claim 12, further comprising 20 - 60 wt% of an inorganic filler based on the total weight of the powder coating composition.

19. The powder coating composition according to claim 12, wherein the powder coating composition can be cured at 230 °C for 30 min.

20. The powder coating composition according to claim 12, wherein the weight loss of the cured coating formed from the powder coating composition is less than 15 wt% after heating at 350 °C for 30 minutes.

21. The powder coating composition according to claim 12, wherein the shear strength of the cured coating formed from the powder coating composition with glue is at least 7 MPa and the pull - out strength with glue is at least 7 MPa after 1000 h of double 85 aging test, and the strength test refers to ASTM D1002 standard.

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