High-toughness mixed powder coating and preparation method thereof

Abstract

The invention discloses a high-toughness mixed powder coating and a preparation method thereof, and belongs to the technical field of powder coating production. The high-toughness mixed powder coating is prepared from the following raw materials in parts by mass: 55 parts of epoxy resin, 42 to 45 parts of hydroxyl polyester resin, 22 to 30 parts of core-shell acrylic copolymer, 5 parts of nano silicon dioxide, 20 parts of titanium dioxide, 1.0 to 1.2 parts of flatting agent and 1.4 to 1.5 parts of melamine cross-linking agent. Through the collaborative design of the core-shell acrylic copolymer flexibilizer and the customized hydroxyl polyester resin, the technical contradiction that high toughness, high surface quality and heat resistance of a traditional powder coating cannot be achieved at the same time is broken through at one stroke on the premise that components are not newly added, and the strict requirements of automobile chassis, outdoor electric boxes and other scenes for the comprehensive performance of the coating are met.

Description

Technical Field

[0001] The invention belongs to the technical field of powder coating production, and particularly relates to a high-toughness mixed powder coating and a preparation method thereof. Background Art

[0002] Powder coatings, as an environmentally friendly coating material, are widely used for metal surface protection and decoration. In recent years, with the increasing demand for lightweight vehicles, refined appearance of home appliances, and weather resistance of outdoor facilities, the mechanical properties of coatings (such as toughness and impact resistance) have become key performance indicators. However, existing powder coating systems are prone to cracking and flaking due to insufficient toughness when exposed to high and low temperature fluctuations, mechanical vibration, or long-term outdoor exposure, seriously affecting the product's service life.

[0003] Traditional polyester / epoxy hybrid powder coatings improve toughness by adding rubber elastomers (such as nitrile rubber), but such toughening agents can cause the following problems: ① poor compatibility with the resin matrix, increased surface roughness of the coating (Ra>1.5μm), affecting the appearance; ② decreased heat resistance, with a yellowing index ΔYI>3.0 after baking at 200°C; ③ during the curing process, the elastomer easily migrates to the coating interface, and the adhesion (cross-hatch method) drops from level 0 to level 2.

[0004] Applications such as automotive chassis components and outdoor high-voltage electrical boxes require coatings with high toughness (impact resistance ≥ 70 cm·kg), resistance to damp heat aging (no blistering after a 1000-hour salt spray test), and high adhesion (cross-hatch grade 0). Existing technologies struggle to achieve both. Simply increasing the amount of toughening agent or introducing new components can easily lead to phase separation, necessitating a performance breakthrough through component synergy and process optimization. Summary of the Invention

[0005] The object of the present invention is to provide a high-toughness mixed powder coating and a preparation method thereof, so as to improve the high toughness, moisture-heat aging resistance and high adhesion of the coating.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A high-toughness mixed powder coating comprises the following raw materials in parts by weight: 55 parts of epoxy resin; 42-45 parts of hydroxy polyester resin; 22-30 parts of core-shell acrylic copolymer; 5 parts of nano silicon dioxide; 20 parts of titanium dioxide; 1.0-1.2 parts of leveling agent; 1.4-1.5 parts of melamine crosslinking agent.

[0007] Furthermore, the hydroxy polyester resin includes the following raw materials in parts by weight: 35 parts of terephthalic acid; 15 parts of isophthalic acid; 8-10 parts of adipic acid; 4-5 parts of trimellitic anhydride; 25 parts of neopentyl glycol; 7-8 parts of trimethylolpropane; 0.3-0.5 parts of monobutyltin oxide.

[0008] Furthermore, the preparation method of the hydroxy polyester resin comprises the following steps: A1. Weigh the raw materials according to their mass, add terephthalic acid, isophthalic acid, adipic acid, neopentyl glycol, and trimethylolpropane into a reaction kettle, and heat to 180°C under nitrogen for esterification for 2-3 hours to obtain a mixture; A2. Add trimellitic anhydride and monobutyltin oxide to the mixture in A1. After completion, heat the reactor to 200-210° C. and stir at constant temperature to react until the acid value reaches 15±1 mg KOH / g. After completion, dehydrate under reduced pressure to an acid value of ≤5 mg KOH / g. After completion, cool and discharge the material to obtain a hydroxy polyester resin.

[0009] Furthermore, the core-shell acrylic copolymer comprises the following raw materials in parts by weight: 70 parts of butyl acrylate; 20 parts of methyl methacrylate; 8 parts of diacetone acrylamide; 30 parts of glycidyl methacrylate; 60 parts of styrene; 10 parts of acrylonitrile; 2 parts of sodium lauryl sulfate; 1 part of alkylphenol polyoxyethylene ether; 1 part potassium persulfate; 150 parts of deionized water.

[0010] Furthermore, the preparation method of the core-shell acrylic copolymer comprises the following steps: B1. Weigh each raw material in parts by mass, add 1.0 part of sodium lauryl sulfate, 0.5 parts of alkylphenol polyoxyethylene ether, butyl acrylate, methyl methacrylate, and diacetone acrylamide to 50 parts of deionized water, and emulsify at 1000 rpm for 15-20 minutes to obtain a core layer pre-emulsion; B2. Mix the remaining 100 parts of deionized water, 0.5 parts of sodium lauryl sulfate, and 0.4 parts of potassium persulfate, raise the temperature to 80-85° C. under nitrogen protection, add the core layer pre-emulsion dropwise within 2 hours, and keep the temperature for reaction for 2-3 hours to obtain the core layer emulsion; B3, mixing glycidyl methacrylate, styrene, acrylonitrile, 0.5 parts of sodium lauryl sulfate and 0.5 parts of alkylphenol polyoxyethylene ether, and emulsifying at 1000 rpm for 10 to 15 minutes to obtain a shell pre-emulsion; B4. Add the remaining 0.6 parts of potassium persulfate to the core layer emulsion, heat the system to 85-90° C., then dropwise add the shell layer pre-emulsion thereto, complete the dropwise addition within 2 hours, keep the reaction warm for 3-4 hours, and after completion, cool to 35-40° C. to obtain an emulsion, and then dropwise add 5% of the emulsion mass of calcium chloride to the emulsion for demulsification. After completion, filter and wash with water 3 times, and finally collect the solid component by suction filtration. The solid component is placed in a vacuum dryer at 60-80° C. for 24 hours to obtain a core-shell acrylic acid copolymer.

[0011] Furthermore, the preparation method of the high-toughness hybrid powder coating comprises the following steps: S1. Premixing: Weighing each raw material according to parts by mass, and then mixing the epoxy resin, hydroxy polyester resin, and core-shell acrylic copolymer in a high-speed mixer for 5 to 10 minutes to obtain a premix; S2, dispersion: adding nano-silica, titanium dioxide, leveling agent and melamine cross-linking agent to the premix in S1, and melt-extruded through a twin-screw extruder to obtain an extrudate; S3, crushing: the extrudate in S2 is crushed to a particle size of D by deep cooling with liquid nitrogen. 50 =40μm, after completion, a high-toughness hybrid powder coating is obtained.

[0012] Furthermore, the epoxy resin is of type E-12; the particle size of the nano-silicon dioxide is 30 nm; the titanium dioxide is of type R-706; the leveling agent is of type BYK-361N; and the melamine cross-linking agent is of type CYMEL 303LF.

[0013] Furthermore, the temperature settings of the twin-screw extruder are: 85-90°C in zone I and 105-110°C in zone II.

[0014] Beneficial effects of the present invention: This invention provides a high-toughness hybrid powder coating and its preparation method. By adding a self-made hydroxyl polyester resin and a core-shell acrylic copolymer, the coating significantly improves its toughness, surface smoothness, heat resistance, adhesion, and corrosion resistance after curing. A detailed analysis is as follows: 1. Improved coating toughness: (1) Comparison of core data: The impact resistance of Examples 5 to 6 reached 78 cm·kg and 80 cm·kg, respectively, far exceeding that of Comparative Example 1 (68 cm·kg) and Comparative Example 3 (30 cm·kg), and significantly higher than the industry demand threshold (≥70 cm·kg) in the background technology.

[0015] (2) Key factors analysis: a. Toughening Effect of Core-Shell Acrylic Copolymer: The impact resistance of Comparative Example 3 (without the core-shell copolymer) plummeted to 30 cm·kg, demonstrating that its core-shell structure (butyl acrylate / diacetone acrylamide as the soft core and epoxy groups as the hard shell) significantly enhances toughness through a stress-dispersing mechanism.

[0016] b. Synergistic effect of the homemade hydroxyl polyester resin: The impact resistance of Comparative Example 1 (replaced with commercially available polyester) dropped to 68 cm·kg, while that of Comparative Example 2 (completely removing the polyester) was only 32 cm·kg. This indicates that the combination of the flexible segment (adipic acid) and the heat-resistant monomer (trimellitic anhydride) in the homemade resin is the basis for maintaining high toughness.

[0017] 2. Both surface smoothness and heat resistance: (1) Optimized surface roughness: The Ra values of Examples 5-6 were only 0.72-0.75 μm, significantly lower than the Ra values of Comparative Example 1 (0.95 μm), Comparative Example 2 (1.85 μm), and the conventional toughening systems in the background art (>1.5 μm). Reason: The shell layer of the core-shell copolymers (Examples 3-4) contains glycidyl methacrylate (GMA), whose epoxy groups react with the resin matrix to enhance compatibility and avoid surface defects caused by elastomer migration.

[0018] (2) Breakthrough in Yellowing Resistance: After baking at 200°C, Examples 5-6 achieved a ΔYI of only 1.8-2.0, surpassing the ΔYI of Comparative Example 1 (2.5), Comparative Example 2 (4.5), and the prior art, which exhibited a ΔYI > 3.0. Key: The trimellitic anhydride in the self-produced polyester resin enhances heat resistance, while the core-shell structure inhibits molecular chain degradation at high temperatures.

[0019] 3. Synergistic enhancement of adhesion and corrosion resistance: (1) Adhesion Stability: The adhesion of Examples 5-6 was grade 0 (cross-hatch method), while that of Comparative Examples 2-3 deteriorated to grades 3 and 4, respectively. Mechanism: The epoxy groups (GMA) in the shell of the core-shell copolymer formed chemical bonds with the substrate, and the trimethylolpropane crosslinking monomer of the homemade polyester enhanced the interfacial bonding strength.

[0020] (2) Improved salt spray resistance: Example 6 achieved a salt spray resistance of 1480 hours (without blistering), a 45% increase over Comparative Example 1 (1020 hours) and far exceeding Comparative Example 3 (350 hours). Reason: Nano-silica (5 parts) was uniformly dispersed within the core-shell structure, forming a dense shielding layer; Furthermore, the hydrolysis stability of the ester bond of the self-made polyester was superior to that of the commercially available resin (compared to Comparative Example 1).

[0021] Conclusion: Through the collaborative design of a core-shell acrylic copolymer toughening agent and a customized hydroxyl polyester resin, the present invention overcomes the technical contradiction of traditional powder coatings that cannot achieve "high toughness, high surface quality, and heat resistance" at one stroke without adding new components, and meets the stringent requirements for comprehensive coating performance in scenarios such as automotive chassis and outdoor electrical boxes. DETAILED DESCRIPTION

[0022] Below in conjunction with the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is obvious that described embodiment is only a part of embodiment of the present invention, rather than whole embodiment. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the scope of protection of the present invention. Meanwhile, raw materials, reagents or devices used in the following examples, unless otherwise specified, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0023] Example 1

[0024] Preparation of hydroxy polyester resin: First, the hydroxy polyester resin includes the following raw materials in parts by weight: Terephthalic acid (industrial grade, purity ≥99%) 35 parts; Isophthalic acid (industrial grade, purity ≥98%) 15 parts; Adipic acid (soft segment, purity ≥99%) 8 parts; 4 parts of trimellitic anhydride (heat-resistant monomer, purity ≥98%); Neopentyl glycol (technical grade) 25 parts; Trimethylolpropane (crosslinking monomer) 7 parts; Monobutyltin oxide (catalyst) 0.3 parts.

[0025] Then, the preparation method of the hydroxy polyester resin comprises the following steps: A1. Weigh the raw materials according to the above parts by mass, add terephthalic acid, isophthalic acid, adipic acid, neopentyl glycol, and trimethylolpropane into a reaction kettle, and heat to 180° C. under nitrogen protection for esterification for 2 hours to obtain a mixture; A2. Trimellitic anhydride and catalyst monobutyl tin oxide were added to the mixture in A1. After completion, the reactor was heated to 200° C. and stirred at constant temperature to react until the acid value reached 15±1 mg KOH / g. After completion, the mixture was dehydrated under reduced pressure (-0.09 MPa) to an acid value of ≤5 mg KOH / g. After testing, the dehydration under reduced pressure in this embodiment was performed to an acid value of 5 mg KOH / g. After completion, the mixture was cooled and discharged to obtain a hydroxy polyester resin.

[0026] Example 2

[0027] Preparation of hydroxy polyester resin: First, the hydroxy polyester resin includes the following raw materials in parts by weight: Terephthalic acid (industrial grade, purity ≥99%) 35 parts; Isophthalic acid (industrial grade, purity ≥98%) 15 parts; Adipic acid (soft segment, purity ≥99%) 10 parts; 5 parts of trimellitic anhydride (heat-resistant monomer, purity ≥98%); Neopentyl glycol (technical grade) 25 parts; 8 parts of trimethylolpropane (crosslinking monomer); Monobutyltin oxide (catalyst) 0.5 parts.

[0028] Then, the preparation method of the hydroxy polyester resin comprises the following steps: A1. Weigh the raw materials according to the above parts by mass, add terephthalic acid, isophthalic acid, adipic acid, neopentyl glycol, and trimethylolpropane into a reaction kettle, and heat to 180° C. under nitrogen protection for esterification for 3 hours to obtain a mixture; A2. Trimellitic anhydride and catalyst monobutyl tin oxide were added to the mixture in A1. After completion, the reactor was heated to 210° C. and stirred at constant temperature until the acid value reached 15±1 mg KOH / g. After completion, the mixture was dehydrated under reduced pressure (-0.09 MPa) to an acid value of ≤5 mg KOH / g. After testing, the dehydration under reduced pressure in this embodiment was performed to an acid value of 4 mg KOH / g. After completion, the mixture was cooled and discharged to obtain a hydroxy polyester resin.

[0029] Example 3

[0030] Preparation of core-shell acrylic copolymer: First, the core-shell acrylic copolymer includes the following raw materials in parts by weight: Nuclear lamina monomers: 70 parts of butyl acrylate; 20 parts of methyl methacrylate; 8 parts of diacetone acrylamide; Shell monomer: 30 parts of glycidyl methacrylate; 60 parts of styrene; 10 parts of acrylonitrile; Emulsifier: 2 parts of sodium lauryl sulfate; 1 part of alkylphenol polyoxyethylene ether; Initiator: 1 part potassium persulfate; 150 parts of deionized water.

[0031] Then, the preparation method of the core-shell acrylic copolymer comprises the following steps: B1. Pre-emulsified core layer monomers: Weigh each raw material according to parts by mass, add 1.0 part of sodium lauryl sulfate (SDS), 0.5 parts of alkylphenol polyoxyethylene ether (OP-10), butyl acrylate (BA), methyl methacrylate (MMA) and diacetone acrylamide (DAAM) to 50 parts of deionized water, and emulsify at 1000 rpm for 15 minutes to obtain a core layer pre-emulsion; B2. Core layer polymerization: Mix the remaining 100 parts of deionized water, 0.5 parts of sodium dodecyl sulfate (SDS), and 0.4 parts of potassium persulfate (KPS), raise the temperature to 80°C under nitrogen protection, add the core layer pre-emulsion dropwise (add it within 2 hours), and keep the temperature to react for 2 hours to obtain the core layer emulsion; B3, pre-emulsified shell monomer: glycidyl methacrylate (GMA), styrene (St), acrylonitrile (AN), 0.5 parts of sodium lauryl sulfate (SDS) and 0.5 parts of alkylphenol polyoxyethylene ether (OP-10) were mixed and emulsified at 1000 rpm for 10 minutes to obtain a shell pre-emulsion; B4. Shell coating: add the remaining 0.6 parts of potassium persulfate (KPS) to the core layer emulsion, heat the system to 85°C, and then drop the shell layer pre-emulsion (dropping is completed in 2 hours), keep the reaction warm for 3 hours, and after completion, cool to 35°C to obtain an emulsion, and then add 5% of the emulsion mass of calcium chloride to the emulsion for demulsification. After completion, filter and wash with water three times, and finally collect the solid component by suction filtration. The solid component is placed at 60°C and vacuum dried for 24 hours to obtain a white powder core-shell acrylic copolymer.

[0032] Example 4

[0033] Preparation of core-shell acrylic copolymer: First, the core-shell acrylic copolymer includes the following raw materials in parts by weight: Nuclear lamina monomers: 70 parts of butyl acrylate; 20 parts of methyl methacrylate; 8 parts of diacetone acrylamide; Shell monomer: 30 parts of glycidyl methacrylate; 60 parts of styrene; 10 parts of acrylonitrile; Emulsifier: 2 parts of sodium lauryl sulfate; 1 part of alkylphenol polyoxyethylene ether; Initiator: 1 part potassium persulfate; 150 parts of deionized water.

[0034] Then, the preparation method of the core-shell acrylic copolymer comprises the following steps: B1. Pre-emulsified core layer monomer: Weigh each raw material according to parts by mass, add 1.0 part of sodium lauryl sulfate (SDS), 0.5 parts of alkylphenol polyoxyethylene ether (OP-10), butyl acrylate (BA), methyl methacrylate (MMA) and diacetone acrylamide (DAAM) to 50 parts of deionized water, and emulsify at 1000 rpm for 20 min to obtain a core layer pre-emulsion; B2. Core layer polymerization: Mix the remaining 100 parts of deionized water, 0.5 parts of sodium dodecyl sulfate (SDS), and 0.4 parts of potassium persulfate (KPS), raise the temperature to 85°C under nitrogen protection, add the core layer pre-emulsion dropwise (add it within 2 hours), and keep the temperature to react for 3 hours to obtain the core layer emulsion; B3, pre-emulsified shell monomer: glycidyl methacrylate (GMA), styrene (St), acrylonitrile (AN), 0.5 parts of sodium lauryl sulfate (SDS) and 0.5 parts of alkylphenol polyoxyethylene ether (OP-10) were mixed and emulsified at 1000 rpm for 15 minutes to obtain a shell pre-emulsion; B4. Shell coating: The remaining 0.6 parts of potassium persulfate (KPS) was added to the core layer emulsion, the system was heated to 90°C, and the shell layer pre-emulsion was added dropwise (dropped over 2 hours), and the reaction was kept warm for 4 hours. After completion, the reaction was cooled to 40°C to obtain an emulsion, and 5% of the mass of the emulsion was added dropwise to the emulsion for demulsification. After completion, the emulsion was filtered and washed with water three times. Finally, the solid component was collected by suction filtration and dried in vacuo at 80°C for 24 hours to obtain a core-shell acrylic copolymer as a white powder.

[0035] Example 5

[0036] Preparation of high-toughness hybrid powder coatings: First, the high-toughness hybrid powder coating includes the following raw materials in parts by weight: 55 parts of epoxy resin; 42 parts of the hydroxy polyester resin prepared in Example 1; 22 parts of the core-shell acrylic copolymer prepared in Example 3; 5 parts of nano silicon dioxide; 20 parts of titanium dioxide; 1.0 part of leveling agent; 1.4 parts of melamine crosslinking agent.

[0037] Then, the preparation method of the high-toughness hybrid powder coating comprises the following steps: S1. Premixing: Weigh each raw material according to parts by mass, then mix the epoxy resin (E-12, epoxy equivalent 450-500), the hydroxy polyester resin prepared in Example 1, and the core-shell acrylic copolymer prepared in Example 3 in a high-speed mixer (speed 2000 rpm) for 5 minutes to obtain a premix; S2, dispersion: nano-silica (particle size 30 nm), titanium dioxide (R-706, rutile type), leveling agent (BYK-361N) and melamine cross-linking agent (CYMEL 303LF) were added to the premix in S1, and melt-extruded through a twin-screw extruder (zone I 85°C, zone II 105°C) to obtain an extrudate; S3, crushing: the extrudate in S2 is crushed to a particle size of D by deep cooling with liquid nitrogen. 50 =40μm, after completion, a high-toughness hybrid powder coating is obtained.

[0038] Example 6

[0039] Preparation of high-toughness hybrid powder coatings: First, the high-toughness hybrid powder coating includes the following raw materials in parts by weight: 55 parts of epoxy resin; 45 parts of the hydroxy polyester resin prepared in Example 2; 30 parts of the core-shell acrylic copolymer prepared in Example 4; 5 parts of nano silicon dioxide; 20 parts of titanium dioxide; 1.2 parts of leveling agent; 1.5 parts of melamine crosslinking agent.

[0040] Then, the preparation method of the high-toughness hybrid powder coating comprises the following steps: S1, premixing: weighing each raw material according to mass parts, and then mixing epoxy resin (E-12, epoxy equivalent 450-500), hydroxy polyester resin prepared in Example 2, and core-shell acrylic copolymer prepared in Example 4 in a high-speed mixer (speed 2000 rpm) for 10 minutes to obtain a premix; S2, dispersion: nano-silica (particle size 30 nm), titanium dioxide (R-706, rutile type), leveling agent (BYK-361N) and melamine cross-linking agent (CYMEL 303LF) were added to the premix in S1, and melt-extruded through a twin-screw extruder (90°C in zone I and 110°C in zone II) to obtain an extrudate; S3, crushing: the extrudate in S2 is crushed to a particle size of D by deep cooling with liquid nitrogen. 50 =40μm, after completion, a high-toughness hybrid powder coating is obtained.

[0041] Comparative Example 1 Comparative Example 1 is the control group of Example 6, except that the hydroxy polyester resin prepared in Example 2 of the raw material in Example 6 is replaced by a commercially available polyester resin (model SJ4ET, purchased from Anhui Shenjian New Materials Co., Ltd.), and the remaining raw materials, raw material amounts and preparation steps remain the same as in Example 6, and finally a high-toughness hybrid powder coating is obtained.

[0042] Comparative Example 2 Comparative Example 2 is the control group of Example 6. The hydroxy polyester resin prepared in Example 2 of the raw material in Example 6 is removed, and the remaining raw materials, raw material amounts and preparation steps are kept consistent with those in Example 6, and finally a high-toughness hybrid powder coating is obtained.

[0043] Comparative Example 3 Comparative Example 3 is the control group of Example 6. The core-shell acrylic copolymer prepared in Example 4 is removed from the raw materials in Example 6, and the remaining raw materials, raw material amounts and preparation steps are kept consistent with those in Example 6, and finally a high-toughness hybrid powder coating is obtained.

[0044] Test Example 1 The performance test of the high-toughness hybrid powder coating prepared in Examples 5 to 6 and Comparative Examples 1 to 3 was carried out. The high-toughness hybrid powder coating was electrostatically sprayed onto the surface of the phosphated steel plate and cured in a step-cured manner at 130°C / 15min+180°C / 10min to form a test sample. The performance test process of the test sample is as follows, and the test results are shown in Table 1: (1) Impact resistance (GB / T 1732-1993): A 1 kg falling ball impacts the back of the coating, and the maximum height (cm·kg) without cracking is recorded; (2) Adhesion (GB / T 9286-1998): Cross-hatch method (1 mm × 1 mm), observe the degree of peeling after the tape is torn off (0 is the best); (3) Surface roughness Ra (GB / T 3505-2009): measured by surface profilometer; (4) Salt spray resistance (GB / T 1771-2007): Spray a 5% volume fraction of NaCl solution and record the coating blistering time (h); (5) Yellowing resistance: Bake at 200℃ for 30min and measure the color difference ΔYI (compared with a standard white board).

[0045] Table 1 Test results project Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Impact resistance (cm·kg) 78 80 68 32 30 Adhesion (cross-hatch method) Level 0 Level 0 Level 0 Level 3 Level 4 Surface roughness Ra (μm) 0.75 0.72 0.95 1.85 2.10 Salt spray resistance time (h) 1450 1480 1020 480 350 ΔYI after baking at 200℃ 2.0 1.8 2.5 4.5 5.0 It should be noted that, in this document, terms such as "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high toughness hybrid powder coating, characterized in that: Including the following raw materials by weight: 55 parts of epoxy resin; 42-45 parts of hydroxy polyester resin; 22-30 parts of core-shell acrylic copolymer; 5 parts of nano silicon dioxide; 20 parts of titanium dioxide; 1.0-1.2 parts of leveling agent; 1.4-1.5 parts of melamine crosslinking agent.

2. A high toughness hybrid powder coating according to claim 1, characterized in that: Including the following raw materials by weight: 55 parts of epoxy resin; 42-45 parts of hydroxy polyester resin; 22-30 parts of core-shell acrylic copolymer; 5 parts of nano silicon dioxide; 20 parts of titanium dioxide; 1.0-1.2 parts of leveling agent; 1.4-1.5 parts of melamine crosslinking agent.

3. A high toughness hybrid powder coating according to claim 2, characterized in that: The preparation method of the hydroxy polyester resin comprises the following steps: A1. Weigh the raw materials according to their mass, add terephthalic acid, isophthalic acid, adipic acid, neopentyl glycol, and trimethylolpropane into a reaction kettle, and heat to 180°C under nitrogen for esterification for 2-3 hours to obtain a mixture; A2. Add trimellitic anhydride and monobutyltin oxide to the mixture in A1. After completion, heat the reactor to 200-210° C. and stir at constant temperature to react until the acid value reaches 15±1 mg KOH / g. After completion, dehydrate under reduced pressure to an acid value of ≤5 mg KOH / g. After completion, cool and discharge the material to obtain a hydroxy polyester resin.

4. The high-toughness hybrid powder coating according to claim 1, characterized in that: The core-shell acrylic copolymer comprises the following raw materials in parts by weight: 70 parts of butyl acrylate; 20 parts of methyl methacrylate; 8 parts of diacetone acrylamide; 30 parts of glycidyl methacrylate; 60 parts of styrene; 10 parts of acrylonitrile; 2 parts of sodium lauryl sulfate; 1 part of alkylphenol polyoxyethylene ether; 1 part potassium persulfate; 150 parts of deionized water.

5. A high toughness hybrid powder coating according to claim 4, characterized in that: The preparation method of the core-shell acrylic copolymer comprises the following steps: B1. Weigh each raw material in parts by mass, add 1.0 part of sodium lauryl sulfate, 0.5 parts of alkylphenol polyoxyethylene ether, butyl acrylate, methyl methacrylate, and diacetone acrylamide to 50 parts of deionized water, and emulsify at 1000 rpm for 15-20 minutes to obtain a core layer pre-emulsion; B2. Mix the remaining 100 parts of deionized water, 0.5 parts of sodium lauryl sulfate, and 0.4 parts of potassium persulfate, raise the temperature to 80-85° C. under nitrogen protection, add the core layer pre-emulsion dropwise within 2 hours, and keep the temperature for reaction for 2-3 hours to obtain the core layer emulsion; B3, mixing glycidyl methacrylate, styrene, acrylonitrile, 0.5 parts of sodium lauryl sulfate and 0.5 parts of alkylphenol polyoxyethylene ether, and emulsifying at 1000 rpm for 10 to 15 minutes to obtain a shell pre-emulsion; B4. Add the remaining 0.6 parts of potassium persulfate to the core layer emulsion, heat the system to 85-90° C., then dropwise add the shell layer pre-emulsion thereto, complete the dropwise addition within 2 hours, keep the reaction warm for 3-4 hours, and after completion, cool to 35-40° C. to obtain an emulsion, and then dropwise add 5% of the emulsion mass of calcium chloride to the emulsion for demulsification. After completion, filter and wash with water 3 times, and finally collect the solid component by suction filtration. The solid component is placed in a vacuum dryer at 60-80° C. for 24 hours to obtain a core-shell acrylic acid copolymer.

6. A method for preparing a high-toughness hybrid powder coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Premixing: Weighing each raw material according to parts by mass, and then mixing the epoxy resin, hydroxy polyester resin, and core-shell acrylic copolymer in a high-speed mixer for 5 to 10 minutes to obtain a premix; S2, dispersion: adding nano-silica, titanium dioxide, leveling agent and melamine cross-linking agent to the premix in S1, and melt-extruded through a twin-screw extruder to obtain an extrudate; S3, crushing: the extrudate in S2 is cryogenically crushed by liquid nitrogen to a particle size of D50 = 40 μm. After completion, a high-toughness mixed powder coating is obtained.

7. The method for preparing a high-toughness hybrid powder coating according to claim 6, characterized in that: The epoxy resin is of type E-12; the particle size of the nano-silicon dioxide is 30 nm; the titanium dioxide is of type R-706; the leveling agent is of type BYK-361N; and the melamine cross-linking agent is of type CYMEL 303LF.

8. The method for preparing a high-toughness hybrid powder coating according to claim 6, characterized in that: The temperature settings of the twin-screw extruder are: 85-90°C in zone I and 105-110°C in zone II.