An environmentally friendly composite high-gloss powder coating and its preparation method

Abstract

This invention discloses an environmentally friendly composite high-gloss powder coating and its preparation method, relating to the field of coating technology. It comprises the following components: silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent. The powder coating prepared by this invention is a novel, solvent-free, 100% solid powder coating. This powder coating possesses multiple characteristics, including being solvent-free, environmentally friendly, pollution-free, recyclable, energy and resource-saving, and exhibiting high mechanical strength of the coating film. It has a wide range of applications and is suitable for use in various fields.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically an environmentally friendly composite high-gloss powder coating and its preparation method. Background Technology

[0002] Powder coatings are solid powdered synthetic resin coatings composed of solid resin, fillers, and additives. Unlike ordinary solvent-based and water-based coatings, their dispersion medium is air, not solvent or water. They feature solvent-free production, 100% film formation, and low energy consumption. Powder coatings are broadly classified into thermoplastic and thermosetting types. Thermoplastic powder coatings have poorer film appearance (gloss and leveling) and weaker adhesion to metals, thus limiting their application in many fields. Thermosetting powder coatings use thermosetting synthetic resins as the film-forming substance. During the drying process, the resin first melts, then undergoes chemical cross-linking and solidifies into a smooth and hard film. The resulting film appearance, various mechanical properties, and corrosion resistance meet the requirements of multiple fields.

[0003] Polyester powder coatings, as an important type of powder coating, have good weather resistance and climate stability, as well as good adhesion and good bonding strength with a variety of substrates.

[0004] However, powder coatings with polyester resin as the main film-forming substance have relatively poor impact resistance and significantly lower gloss due to the insufficient bond energy of C-O and C-C bonds.

[0005] Based on this, an environmentally friendly composite high-gloss powder coating and its preparation method are provided to solve the existing technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide an environmentally friendly composite high-gloss powder coating and its preparation method, so as to overcome the shortcomings of the prior art.

[0007] The technical solution adopted in this invention is as follows:

[0008] An environmentally friendly composite high-gloss powder coating is made of the following components by weight: 90-98 parts of silicon-carbon modified polyester resin, 5-9 parts of curing agent, 5-8 parts of diatomaceous earth, 0.5-0.8 parts of additives, 18-23 parts of composite filler, 0.5-0.8 parts of antioxidant, 1-2 parts of tributyl citrate, 1.5-3 parts of calcium stearate, 0.5-1 part of benzoin, and 1-2 parts of leveling agent.

[0009] As a further technical solution: the method for preparing the auxiliary agent is as follows:

[0010] (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65℃, keep it at the temperature, stir and mix at 150r / min for 15min to obtain the base liquid;

[0011] (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution;

[0012] (3) The initiator solution prepared in step (2) is added dropwise to the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

[0013] As a further technical solution: the organic solvent is xylene;

[0014] The mass ratio of xylene to methyl methacrylate is 35:5-8;

[0015] The initiator is benzoyl peroxide;

[0016] The initiator solution has a mass fraction of 3.25%.

[0017] The mass ratio of the initiator solution to the base liquid is 1:6-8.

[0018] As a further technical solution: the method for preparing the silicon-carbon modified polyester resin is as follows:

[0019] Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor at a molar ratio of 3:1-2. The mixture was then heated to 50°C and stirred for 30 minutes. Graphene was then added, and the system was evacuated to 0.5 Pa and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added. The temperature was adjusted to 80°C and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier.

[0020] The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

[0021] As a further technical solution: the mass ratio of the octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:1-3:2:0.5:1.

[0022] As a further technical solution: the catalyst is potassium persulfate;

[0023] The coupling agent is a titanate coupling agent.

[0024] As a further technical solution: the mass ratio of the modifier to the polyester resin is 3-5:40-45.

[0025] As a further technical solution: the curing agent is curing agent T105;

[0026] The leveling agent is polyacrylate;

[0027] The antioxidant is 1010.

[0028] As a further technical solution: the composite filler is titanium dioxide, calcium titanate, and zeolite powder;

[0029] The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:1.

[0030] A method for preparing an environmentally friendly composite high-gloss powder coating includes the following steps:

[0031] S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained.

[0032] The mixing speed is 550 r / min;

[0033] S2. Add the above mixture to a twin-screw extruder and melt-extrude it;

[0034] S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating.

[0035] Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.

[0036] Beneficial effects:

[0037] The powder coating prepared by this invention is a novel solvent-free, 100% solid powder coating. This powder coating possesses numerous advantages, including being solvent-free, environmentally friendly, pollution-free, recyclable, energy and resource-saving, and exhibiting high mechanical strength. It has a wide range of applications and is suitable for use in various fields.

[0038] This invention modifies polyester resin, effectively reducing the overall melt viscosity of the resin, thereby greatly improving the impact and leveling properties of the powder coating, as well as significantly enhancing the temperature resistance of the coating. The powder coating prepared by this invention can be used for a long time at 350°C, greatly expanding the application of powder coatings in high-temperature fields.

[0039] Due to the special modification of polyester resin in this invention, mainly the introduction of silicon and carbon, the problem of powder coatings easily agglomerating under high-temperature environments can be effectively avoided, thus ensuring the normal spraying of powder coatings and improving the convenience of spraying. Furthermore, the powder coating prepared by this invention exhibits good leveling and appearance after curing, effectively forming a high-leveling decorative effect and significantly improving the quality of the coating.

[0040] The introduction of conventional leveling agents improves the leveling performance of coatings to some extent, but it is still difficult to achieve a high degree of leveling in the prepared coating. Therefore, this invention introduces a variety of active groups by modifying polyester resin, and in combination with the use of leveling agents, it can further improve the leveling performance of the coating. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] An environmentally friendly composite high-gloss powder coating is made of the following components by weight: 90 parts of silicon-carbon modified polyester resin, 5 parts of curing agent, 5 parts of diatomaceous earth, 0.5 parts of additives, 18 parts of composite filler, 0.5 parts of antioxidant, 1 part of tributyl citrate, 1.5 parts of calcium stearate, 0.5 parts of benzoin, and 1 part of leveling agent.

[0044] The preparation method of the auxiliary agent is as follows:

[0045] (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65℃, keep it at the temperature, stir and mix at 150r / min for 15min to obtain the base liquid;

[0046] (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution;

[0047] (3) The initiator solution prepared in step (2) is added dropwise to the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

[0048] The organic solvent is xylene;

[0049] The mass ratio of xylene to methyl methacrylate is 35:5.

[0050] The initiator is benzoyl peroxide;

[0051] The initiator solution has a mass fraction of 3.25%.

[0052] The initiator solution and base liquid are mixed in a mass ratio of 1:6.

[0053] The preparation method of silicon-carbon modified polyester resin is as follows:

[0054] Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor in a 3:1 molar ratio, then heated to 50°C and stirred for 30 min. Graphene was then added, the system was evacuated to 0.5 Pa, and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added, the temperature was adjusted to 80°C, and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier.

[0055] The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

[0056] The mass ratio of octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:1:2:0.5:1.

[0057] The catalyst is potassium persulfate.

[0058] The coupling agent is a titanate coupling agent.

[0059] The mass ratio of the modifier to the polyester resin is 3:40.

[0060] The curing agent is curing agent T105;

[0061] The leveling agent is polyacrylate;

[0062] The antioxidant is 1010.

[0063] The composite filler is composed of titanium dioxide, calcium titanate, and zeolite powder;

[0064] The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:1.

[0065] A method for preparing an environmentally friendly composite high-gloss powder coating includes the following steps:

[0066] S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained.

[0067] The mixing speed is 550 r / min;

[0068] S2. Add the above mixture to a twin-screw extruder and melt-extrude it;

[0069] S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating.

[0070] Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.

[0071] Example 2

[0072] An environmentally friendly composite high-gloss powder coating is made of the following components by weight: 92 parts of silicon-carbon modified polyester resin, 6 parts of curing agent, 7 parts of diatomaceous earth, 0.55 parts of additives, 20 parts of composite filler, 0.6 parts of antioxidant, 1.5 parts of tributyl citrate, 1.8 parts of calcium stearate, 0.7 parts of benzoin, and 1.2 parts of leveling agent.

[0073] The preparation method of the auxiliary agent is as follows:

[0074] (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65℃, keep it at the temperature, stir and mix at 150r / min for 15min to obtain the base liquid;

[0075] (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution;

[0076] (3) The initiator solution prepared in step (2) is added dropwise to the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

[0077] The organic solvent is xylene;

[0078] The mass ratio of xylene to methyl methacrylate is 35:6;

[0079] The initiator is benzoyl peroxide;

[0080] The initiator solution has a mass fraction of 3.25%.

[0081] The initiator solution and base liquid are mixed in a mass ratio of 1:7.

[0082] The preparation method of silicon-carbon modified polyester resin is as follows:

[0083] Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor at a molar ratio of 3:1.5. The mixture was then heated to 50°C and stirred for 30 minutes. Graphene was then added, and the system was evacuated to 0.5 Pa and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added. The temperature was adjusted to 80°C and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier.

[0084] The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

[0085] The mass ratio of octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:2:2:0.5:1.

[0086] The catalyst is potassium persulfate.

[0087] The coupling agent is a titanate coupling agent.

[0088] The mass ratio of modifier to polyester resin is 3.5:42.

[0089] The curing agent is curing agent T105;

[0090] The leveling agent is polyacrylate;

[0091] The antioxidant is 1010.

[0092] The composite filler is composed of titanium dioxide, calcium titanate, and zeolite powder;

[0093] The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:1.

[0094] A method for preparing an environmentally friendly composite high-gloss powder coating includes the following steps:

[0095] S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained.

[0096] The mixing speed is 550 r / min;

[0097] S2. Add the above mixture to a twin-screw extruder and melt-extrude it;

[0098] S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating.

[0099] Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.

[0100] Example 3

[0101] An environmentally friendly composite high-gloss powder coating is made of the following components by weight: 95 parts of silicon-carbon modified polyester resin, 7 parts of curing agent, 6 parts of diatomaceous earth, 0.6 parts of additives, 21 parts of composite filler, 0.6 parts of antioxidant, 1.6 parts of tributyl citrate, 2 parts of calcium stearate, 0.8 parts of benzoin, and 1.5 parts of leveling agent.

[0102] The preparation method of the auxiliary agent is as follows:

[0103] (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65℃, keep it at the temperature, stir and mix at 150r / min for 15min to obtain the base liquid;

[0104] (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution;

[0105] (3) The initiator solution prepared in step (2) is added dropwise to the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

[0106] The organic solvent is xylene;

[0107] The mass ratio of xylene to methyl methacrylate is 35:6;

[0108] The initiator is benzoyl peroxide;

[0109] The initiator solution has a mass fraction of 3.25%.

[0110] The initiator solution and base liquid are mixed in a mass ratio of 1:7.

[0111] The preparation method of silicon-carbon modified polyester resin is as follows:

[0112] Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor at a molar ratio of 3:1.5. The mixture was then heated to 50°C and stirred for 30 minutes. Graphene was then added, and the system was evacuated to 0.5 Pa and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added. The temperature was adjusted to 80°C and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier.

[0113] The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

[0114] The mass ratio of octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:2:2:0.5:1.

[0115] The catalyst is potassium persulfate.

[0116] The coupling agent is a titanate coupling agent.

[0117] The mass ratio of the modifier to the polyester resin is 4:43.

[0118] The curing agent is curing agent T105;

[0119] The leveling agent is polyacrylate;

[0120] The antioxidant is 1010.

[0121] The composite filler is composed of titanium dioxide, calcium titanate, and zeolite powder;

[0122] The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:1.

[0123] A method for preparing an environmentally friendly composite high-gloss powder coating includes the following steps:

[0124] S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained.

[0125] The mixing speed is 550 r / min;

[0126] S2. Add the above mixture to a twin-screw extruder and melt-extrude it;

[0127] S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating.

[0128] Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.

[0129] Example 4

[0130] An environmentally friendly composite high-gloss powder coating is made of the following components by weight: 96 parts of silicon-carbon modified polyester resin, 8 parts of curing agent, 7 parts of diatomaceous earth, 0.6 parts of additives, 21 parts of composite filler, 0.7 parts of antioxidant, 1.5 parts of tributyl citrate, 2 parts of calcium stearate, 0.8 parts of benzoin, and 1.4 parts of leveling agent.

[0131] The preparation method of the auxiliary agent is as follows:

[0132] (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65℃, keep it at the temperature, stir and mix at 150r / min for 15min to obtain the base liquid;

[0133] (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution;

[0134] (3) The initiator solution prepared in step (2) is added dropwise to the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

[0135] The organic solvent is xylene;

[0136] The mass ratio of xylene to methyl methacrylate is 35:7.

[0137] The initiator is benzoyl peroxide;

[0138] The initiator solution has a mass fraction of 3.25%.

[0139] The initiator solution and base liquid are mixed in a mass ratio of 1:6.

[0140] The preparation method of silicon-carbon modified polyester resin is as follows:

[0141] Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor in a 3:1 molar ratio, then heated to 50°C and stirred for 30 min. Graphene was then added, the system was evacuated to 0.5 Pa, and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added, the temperature was adjusted to 80°C, and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier.

[0142] The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

[0143] The mass ratio of octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:2:2:0.5:1.

[0144] The catalyst is potassium persulfate.

[0145] The coupling agent is a titanate coupling agent.

[0146] The mass ratio of the modifier to the polyester resin is 4:42.

[0147] The curing agent is curing agent T105;

[0148] The leveling agent is polyacrylate;

[0149] The antioxidant is 1010.

[0150] The composite filler is composed of titanium dioxide, calcium titanate, and zeolite powder;

[0151] The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:1.

[0152] A method for preparing an environmentally friendly composite high-gloss powder coating includes the following steps:

[0153] S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained.

[0154] The mixing speed is 550 r / min;

[0155] S2. Add the above mixture to a twin-screw extruder and melt-extrude it;

[0156] S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating.

[0157] Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.

[0158] Example 5

[0159] An environmentally friendly composite high-gloss powder coating is made of the following components by weight: 98 parts of silicon-carbon modified polyester resin, 9 parts of curing agent, 8 parts of diatomaceous earth, 0.8 parts of additives, 23 parts of composite filler, 0.8 parts of antioxidant, 2 parts of tributyl citrate, 3 parts of calcium stearate, 1 part of benzoin, and 2 parts of leveling agent.

[0160] The preparation method of the auxiliary agent is as follows:

[0161] (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65℃, keep it at the temperature, stir and mix at 150r / min for 15min to obtain the base liquid;

[0162] (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution;

[0163] (3) The initiator solution prepared in step (2) is added dropwise to the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

[0164] The organic solvent is xylene;

[0165] The mass ratio of xylene to methyl methacrylate is 35:8.

[0166] The initiator is benzoyl peroxide;

[0167] The initiator solution has a mass fraction of 3.25%.

[0168] The initiator solution and base liquid are mixed in a mass ratio of 1:8.

[0169] The preparation method of silicon-carbon modified polyester resin is as follows:

[0170] Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor in a 3:2 molar ratio, then heated to 50°C and stirred for 30 min. Graphene was then added, the system was evacuated to 0.5 Pa, and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added, the temperature was adjusted to 80°C, and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier.

[0171] The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

[0172] The mass ratio of octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:3:2:0.5:1.

[0173] The catalyst is potassium persulfate.

[0174] The coupling agent is a titanate coupling agent.

[0175] The mass ratio of the modifier to the polyester resin is 5:45.

[0176] The curing agent is curing agent T105;

[0177] The leveling agent is polyacrylate;

[0178] The antioxidant is 1010.

[0179] The composite filler is composed of titanium dioxide, calcium titanate, and zeolite powder;

[0180] The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:1.

[0181] A method for preparing an environmentally friendly composite high-gloss powder coating includes the following steps:

[0182] S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained.

[0183] The mixing speed is 550 r / min;

[0184] S2. Add the above mixture to a twin-screw extruder and melt-extrude it;

[0185] S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating.

[0186] Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.

[0187] Comparative Example 1:

[0188] The difference from Example 1 is that no additives are added, but the rest of the technical solutions remain the same.

[0189] Comparative Example 2:

[0190] The difference from Example 1 is that the silicon-carbon modified polyester resin is replaced with unmodified polyester resin, while the rest of the technical solutions remain the same.

[0191] test:

[0192] Test methods

[0193] The coatings from the examples and comparative examples were sprayed onto the surface of glass plates (10 samples per group, the final result being the average value), with a thickness difference not exceeding 0.05 mm. After curing under the same conditions, the gloss of the coatings was measured according to ISO 2813.

[0194] Table 1

[0195] Example 1 81 Example 2 84 Example 3 86 Example 4 79 Example 5 81 Comparative Example 1 51

[0196] As can be seen from Table 1, the powder coating prepared by the present invention has a high gloss after curing.

[0197] The gelation time of powder coatings shall be tested in accordance with HG / T2006—2006, and the test temperature shall be 180℃.

[0198] Table 2

[0199] Example 1 568 Example 2 549 Example 3 553 Example 4 557 Example 5 552 Comparative Example 2 367

[0200] As can be seen from Table 2, the gelation time of the powder coating prepared by the present invention is longer than that of the comparative example. This gelation time is moderate and is more conducive to the coating obtaining good leveling and curing degree.

[0201] Impact resistance performance was tested according to GB / T1732—1993:

[0202] Table 3

[0203] Example 1 Positive and negative microcracks Example 2 Positive and negative microcracks Example 3 Positive and negative microcracks Example 4 Positive and negative microcracks Example 5 Positive and negative microcracks Comparative Example 2 Front and back fall off

[0204] As can be seen from Table 3, the coating formed by the coating of the present invention has high impact resistance.

[0205] The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall be within the protection scope of the present invention as long as they do not exceed the spirit covered by the specification.

Claims

1. An environmentally friendly composite high-gloss powder coating, characterized in that, It is made of the following components by weight: 90-98 parts of silicon-carbon modified polyester resin, 5-9 parts of curing agent, 5-8 parts of diatomaceous earth, 0.5-0.8 parts of additives, 18-23 parts of composite filler, 0.5-0.8 parts of antioxidant, 1-2 parts of tributyl citrate, 1.5-3 parts of calcium stearate, 0.5-1 part of benzoin, and 1-2 parts of leveling agent; The method for preparing the silicon-carbon modified polyester resin is as follows: Octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane were added to the reactor at a molar ratio of 3:1-2. The mixture was then heated to 50°C and stirred for 30 minutes. Graphene was then added, and the system was evacuated to 0.5 Pa and stirred for 2 hours. Maleic anhydride, catalyst, and coupling agent were then added. The temperature was adjusted to 80°C and stirred for 4 hours. The mixture was then cooled, discharged, and dried to obtain the modifier. The modifier and polyester resin obtained above were added to a twin-screw extruder for melt extrusion and granulation to obtain silicon-carbon modified polyester resin.

2. The environmentally friendly composite high-gloss powder coating according to claim 1, characterized in that: The preparation method of the auxiliary agent is as follows: (1) First, add methyl methacrylate to the reactor, then add organic solvent to the reactor, adjust the temperature to 65°C, keep it warm, and stir and mix at 150 r / min for 15 min to obtain the base liquid; (2) Add the initiator to the same organic solvent as in step (1), and stir and mix evenly at 150 r / min at room temperature to obtain an initiator solution; (3) The initiator solution prepared in step (2) is added dropwise into the reaction vessel in step (1), and then the reaction is carried out at 70°C with stirring for 1.5 hours. First, a portion of the organic solvent is removed by atmospheric distillation, and then the remaining organic solvent is removed by vacuum distillation. Finally, the mixture is pulverized and then passed through a 350-mesh sieve to obtain the auxiliary agent.

3. The environmentally friendly composite high-gloss powder coating according to claim 2, characterized in that: The organic solvent is xylene; The mass ratio of xylene to methyl methacrylate is 35:5-8; The initiator is benzoyl peroxide; The initiator solution has a mass fraction of 3.25%. The mass ratio of the initiator solution to the base liquid is 1:6-8.

4. The environmentally friendly composite high-gloss powder coating according to claim 1, characterized in that: The mass ratio of the octamethylcyclotetrasiloxane, graphene, maleic anhydride, catalyst, and coupling agent is 10:1-3:2:0.5:

1.

5. The environmentally friendly composite high-gloss powder coating according to claim 4, characterized in that: The catalyst is potassium persulfate; The coupling agent is a titanate coupling agent.

6. The environmentally friendly composite high-gloss powder coating according to claim 5, characterized in that: The mass ratio of the modifier to the polyester resin is 3-5:40-45.

7. The environmentally friendly composite high-gloss powder coating according to claim 1, characterized in that: The curing agent is curing agent T105; The leveling agent is polyacrylate; The antioxidant is 1010.

8. The environmentally friendly composite high-gloss powder coating according to claim 1, characterized in that: The composite filler is titanium dioxide, calcium titanate, and zeolite powder; The mass ratio of titanium dioxide, calcium titanate, and zeolite powder is 3:15:

1.

9. The method for preparing an environmentally friendly composite high-gloss powder coating according to claim 1, characterized in that, Includes the following steps: S1. First, add silicon-carbon modified polyester resin, curing agent, diatomaceous earth, additives, composite filler, antioxidant, tributyl citrate, calcium stearate, benzoin, and leveling agent to the mixer and mix for 15 minutes. Then, heat the mixture to 120°C under negative pressure and continue mixing for 20 minutes until a mixture is obtained. The mixing speed is 550 r / min; S2. Add the above mixture to a twin-screw extruder and melt-extrude it; S3. After being melt-extruded by a twin-screw extruder, the material is conveyed to a tablet press for tableting to obtain a sheet. The sheet is then crushed, sieved, and packaged to obtain an environmentally friendly composite high-gloss powder coating. Among them, the environmentally friendly composite high-gloss powder coating has an average particle size of 40μm.