A polyester resin powder coating with high adhesion and its preparation method

Abstract

The present invention discloses a high-adhesion polyester resin powder coating and a preparation method thereof, relating to the technical field of polyester resin powder coatings. The coating comprises the following raw materials: a thermosetting polyester resin, triglycidyl isocyanurate, blocked isocyanate, 2-hydroxyethyl methacrylate phosphate, zirconate, barium sulfate, sericite powder, fumed silica and polytetrafluoroethylene wax. Among them, the present invention adopts a double-curing system of triglycidyl isocyanurate and blocked isocyanate, which can quickly crosslink to form a rigid network. During the process of the coating forming a coating layer, the main body strength is enhanced first, and then the adhesion is enhanced through interfacial chemical bonds, solving the problem of interlayer peeling of traditional coatings. The high-adhesion polyester resin powder coating of the present invention can eliminate the pretreatment and has high adhesion, salt spray resistance and impact resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester resin powder coatings, and specifically relates to a high-adhesion polyester resin powder coating and a preparation method thereof. Background Art

[0002] Traditional polyester resin powder coatings are widely used in the field of metal coating, but their adhesion usually depends on the pretreatment of substrate phosphating, sandblasting or chromating, which not only increases the production cost but also involves environmental protection issues. In addition, conventional powder coatings have a low tolerance to slight oil stains or oxide layers, which easily leads to a decrease in coating adhesion, especially interface peeling is likely to occur in humid and hot or salt spray environments. In the prior art, although there are some powder coating solutions without pretreatment (such as using silane coupling agents or epoxy-modified resins), there are still the following problems: (1) Insufficient adhesion: Silane coupling agents are prone to hydrolysis and failure during high-temperature curing, resulting in poor long-term water resistance; (2) Poor process compatibility: Some solutions require curing at temperatures above 200°C, with high energy consumption and easy yellowing of the coating; (3) High cost: Using special resins such as fluorine-containing polyesters or nanomaterials such as graphene will significantly increase the raw material cost. Summary of the Invention

[0003] In order to overcome the above technical problems, the present invention provides a high-adhesion polyester resin powder coating and a preparation method thereof. The high-adhesion polyester resin powder coating of the present invention can be free of pretreatment and has high adhesion, salt spray resistance and impact resistance.

[0004] The present invention solves the above technical problems through the following technical solutions.

[0005] The present invention discloses a high-adhesion polyester resin powder coating, comprising the following raw materials: thermosetting polyester resin, triglycidyl isocyanurate (TGIC), blocked isocyanate, 2-hydroxyethyl methacrylate phosphate, zirconate, barium sulfate, sericite powder, fumed silica and polytetrafluoroethylene wax;

[0006] The thermosetting polyester resin comprises the following raw materials in parts by mass: 25-50 parts of PTA (terephthalic acid), 10-30 parts of IPA (isophthalic acid), 3-18 parts of NDA (2,6-naphthalenedicarboxylic acid), 3-12 parts of AA (adipic acid), 45-75 parts of NPG (neopentyl glycol), 8-25 parts of BEPD (2-butyl-2-ethyl-1,3-propanediol), 2-10 parts of TMP (trimethylolpropane), 1-6 parts of CTBN (carboxyl-terminated polybutadiene), 0.1-0.5 part of antioxidant and 0.005-0.1 part of catalyst;

[0007] The preparation method of the thermosetting polyester resin comprises the following steps: subjecting the raw materials of the thermosetting polyester resin except CTBN and antioxidant to esterification dehydration and polycondensation reaction; then adding CTBN for graft modification; adding antioxidant and discharging, and molding to obtain granular thermosetting polyester resin.

[0008] Among them, the present invention adopts a double-curing system of triglycidyl isocyanurate and blocked isocyanate, which can quickly crosslink to form a rigid network. During the process of the coating forming a coating layer, the main body strength is enhanced first, and then the adhesion is enhanced through interfacial chemical bonds, solving the problem of interlayer peeling of traditional coatings. In the phosphate-zirconate synergistic coupling system, 2-hydroxyethyl methacrylate phosphate avoids interfacial delamination through the dual effects of chemical chelation and physical anchoring (penetrating into the micropores of the substrate), and also endows the coating with excellent adhesion; the zirconate coupling agent forms zirconium-oxygen-metal bonds at the coating-metal interface, and the bond strength is much higher than that of hydrogen bonds, significantly improving the salt spray resistance. Sericite powder is oriented during the extrusion process to block the penetration of water vapor and ions, and polytetrafluoroethylene wax migrates to the surface of the coating during curing to form a hydrophobic layer. Fumed silica is a hydrophobic treatment agent.

[0009] Preferably, the high-adhesion polyester resin powder coating comprises the following raw materials in parts by mass: 45-60 parts of thermosetting polyester resin, 3.5-5.5 parts of triglycidyl isocyanurate, 1-2.5 parts of blocked isocyanate, 2-5 parts of 2-hydroxyethyl methacrylate phosphate, 0.5-2.0 parts of zirconate, 20-30 parts of barium sulfate, 5-12 parts of sericite powder, 0.5-1.2 parts of fumed silica and 1-2 parts of polytetrafluoroethylene wax;

[0010] More preferably, the high-adhesion polyester resin powder coating comprises the following raw materials in parts by mass: 48-52 parts of thermosetting polyester resin, 4.0-4.5 parts of triglycidyl isocyanurate, 1.3-1.7 parts of blocked isocyanate, 2.8-3.5 parts of 2-hydroxyethyl methacrylate phosphate, 1.0-1.5 parts of zirconate, 23-27 parts of barium sulfate, 7-9 parts of sericite powder, 0.7-0.9 parts of fumed silica and 1.3-1.7 parts of polytetrafluoroethylene wax.

[0011] The antioxidant is Irganox 1010 or Irganox 1330.

[0012] The catalyst is a conventional catalyst in the art and can be monobutyltin oxide.

[0013] Among them, AA can increase the chain segment ductility; the rigid naphthalene ring structure of NDA can improve the aging resistance and adhesion; TMP introduces a branched structure to enhance the crosslinking performance; BEPD is a branched alkyl structure to reduce the crystallinity and enhance the adhesion; CTBN is pre-reacted and grafted onto the polyester chain to improve the impact strength and metal adhesion.

[0014] Preferably, the thermosetting polyester resin comprises the following raw materials in parts by mass: 35-42 parts of PTA, 18-22 parts of IPA, 8-12 parts of NDA, 5-8 parts of AA, 55-65 parts of NPG, 12-18 parts of BEPD, 4-6 parts of TMP, 2-4 parts of CTBN, 0.1-0.3 part of antioxidant and 0.02-0.04 part of catalyst.

[0015] Further, the esterification dehydration is carried out by heating at a heating rate of 5-15 °C / min to 170-220 °C for dehydration until the amount of distilled water reaches more than 85% of the theoretical value; preferably, the esterification dehydration is carried out by heating at a heating rate of 8-10 °C / min to 180-190 °C for dehydration until the amount of distilled water reaches more than 90% of the theoretical value.

[0016] Further, the esterification dehydration needs to be carried out under nitrogen protection, and the flow rate of nitrogen is 3-5 L / min.

[0017] Further, the stirring speed of the esterification dehydration is 50-80 rpm.

[0018] Further, the temperature of the polycondensation reaction is 230-240 °C.

[0019] Further, the polycondensation reaction is carried out until the acid value reaches 8-14 mg KOH / g.

[0020] Further, the polycondensation reaction needs to maintain a vacuum degree of -0.095 to -0.09 MPa.

[0021] Further, the temperature of the graft modification is 230-240 °C.

[0022] Further, the graft modification is carried out until the acid value reaches 30-36 mg KOH / g.

[0023] Further, before discharging, the temperature needs to be reduced to 160-180 °C, and antioxidant is added and stirred for 15-30 min.

[0024] Further, the molding is carried out by using a granulator.

[0025] In some preferred embodiments, the acid value of the 2-hydroxyethyl methacrylate phosphate is 250-310 mgKOH / g.

[0026] In some preferred embodiments, the NCO content of the blocked isocyanate is 4-6%, for example 5.4%.

[0027] In some preferred embodiments, the viscosity of the blocked isocyanate is 500-800 mps, 600 mps.

[0028] In some preferred embodiments, the zirconate is tetrabutyl zirconate (CAS No.: 1071-76-7) or tetra(triethanolamine) zirconate (CAS No.: 101033-44-7).

[0029] In some preferred embodiments, the barium sulfate is precipitated barium sulfate.

[0030] In some preferred embodiments, the D98 of the barium sulfate is 2 - 5 μm.

[0031] In some preferred embodiments, the nitrogen adsorption specific surface area of the fumed silica is 110 - 150 m 2 / g.

[0032] In some preferred embodiments, the carbon content of the fumed silica is 0.5 - 4%.

[0033] In some preferred embodiments, the tapped density of the fumed silica is 40 - 60 g / L. In some preferred embodiments, the D50 of the polytetrafluoroethylene wax is 4 - 7 μm.

[0034] The preparation method of the aforementioned high - adhesion polyester resin powder coating comprises the following steps:

[0035] The raw materials for preparing the high - adhesion polyester resin powder coating are dry - mixed evenly and then melt - extruded, pressed into tablets, crushed, and sieved to obtain the high - adhesion polyester resin powder coating.

[0036] In some preferred embodiments, the dry - mixing evenly is carried out using a high - speed mixer.

[0037] In some preferred embodiments, the rotation speed of the dry - mixing evenly is 500 - 800 rpm, and the stirring time of the dry - mixing evenly is 3 - 8 min.

[0038] In some preferred embodiments, the melt - extrusion is carried out using a twin - screw extruder.

[0039] In some preferred embodiments, the temperature of the melt - extrusion is 85 - 90 °C in zone I, 100 - 105 °C in zone II, and 110 - 115 °C in zone III.

[0040] In some preferred embodiments, the screw rotation speed of the melt - extrusion is 300 - 400 rpm.

[0041] In some preferred embodiments, during the melt - extrusion process, vacuum degassing is required to - 0.05 - - 0.03 MPa.

[0042] In some preferred embodiments, after pressing into tablets, it is also necessary to cool with liquid nitrogen to - 40 - - 30 °C.

[0043] In some preferred embodiments, the sieving is such that D90 ≤ 40 μm.

[0044] The application method of the above-mentioned high-adhesion polyester resin powder coating: The high-adhesion polyester resin powder coating can be cured after electrostatic spraying.

[0045] The voltage of the electrostatic spraying is 50 - 70 kV.

[0046] The curing conditions are curing at 170 - 190 °C for 10 - 20 min; preferably, the curing is at 170 - 180 °C for 10 - 15 min.

[0047] On the basis of conforming to the common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] The high-adhesion polyester resin powder coating developed by the present invention has significant performance advantages. This coating does not require pretreatment of the metal substrate. Through the synergistic system of phosphate - zirconate (combining chemical chelation and physical anchoring) and the double-curing system (the synergistic effect of TGIC and blocked isocyanate), 0-level adhesion of the coating to the metal substrate can be achieved. The present invention also realizes the balance of flowability and hydrophobicity by optimizing the filler ratio and additives. The curing temperature can be as low as 180 °C, significantly reducing energy consumption. At the same time, all the raw materials used can be domesticated, making the cost much lower than that of imported products.

[0050] The thermosetting polyester resin adopts a system of three composite acids of PTA / IPA / NDA and three composite alcohols of NPG / BEPD / TMP, and is toughened by combining CTBN, making it have both high hardness (due to the rigid structure of the naphthalene ring), weather resistance, and impact resistance. In addition, by introducing a branched structure (TMP / BEPD), the crosslinking density and coating adhesion are further improved. Detailed Embodiments

[0051] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in combination with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0052] Unless otherwise defined, all the professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0053] The "range" disclosed by the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or exclude the end values, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present invention, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] If there is no special instruction, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0055] If there is no special instruction, all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0056] If there is no special instruction, all steps of the present invention can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0057] If there is no special instruction, the "including" and "comprising" mentioned in the present invention mean open-ended or can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can also mean only the components listed are included or comprised.

[0058] Unless otherwise specified, the term "or" is inclusive in the present invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or present) and B is false (or absent); A is false (or absent) while B is true (or present); or both A and B are true (or present).

[0059] The raw material information used in the following examples is as follows:

[0060] The blocked isocyanate was purchased from Guangzhou Wanjun Chemical's blocked isocyanate crosslinker C68, with an HDI content of 65%, an NCO content of 5.4%, and a viscosity of 600 mps at 25 °C;

[0061] 2-Hydroxyethyl methacrylate phosphate (CAS No.: 52628-03-2) was purchased from Guangzhou Chongjian Chemical's PM-2, with an acid value of 250 - 310 mgKOH / g;

[0062] Precipitated barium sulfate was purchased from Hongzhi New Materials' AB1000, with D98 = 2 μm and D50 = 1.0 μm.

[0063] Fumed silica was purchased from Huifu Electronics' hydrophobic HB-612, with a nitrogen adsorption specific surface area of 140 ± 20 m 2 / g, a carbon content of 0.7 - 1.3%, and a tapped density of 40 - 60 g / L;

[0064] Polytetrafluoroethylene powder was purchased from Nanjing Tianshi New Materials' PTFE-0107, with D50 = 5 - 7 μm;

[0065] Sericite powder was purchased from Anhui Gerui New Material Technology Co., Ltd.'s GA-1, with D50 = 16 μm and an oil absorption of 25 - 50 g / 100 g;

[0066] Including but not limited to the above raw material manufacturers and models.

[0067] Example 1

[0068] The high-adhesion polyester resin powder coating of this example is composed of the following raw materials in parts by mass: 50 parts of thermosetting polyester resin, 4.5 parts of triglycidyl isocyanurate, 1.5 parts of blocked isocyanate, 3.2 parts of 2-hydroxyethyl methacrylate phosphate, 1.3 parts of zirconate (tetrabutyl zirconate), 27 parts of barium sulfate, 7 parts of sericite powder, 0.9 part of fumed silica, and 1.3 parts of polytetrafluoroethylene wax.

[0069] The thermosetting polyester resin is composed of the following raw materials in parts by mass: 40 parts of PTA, 18 parts of IPA, 10 parts of NDA, 5 parts of AA, 55 parts of NPG, 18 parts of BEPD, 6 parts of TMP, 4 parts of CTBN, 0.2 part of antioxidant (Irganox 1010), and 0.05 part of catalyst (Fascat 4101);

[0070] Preparation method of the thermosetting polyester resin: Put the raw materials of the above thermosetting polyester resin except CTBN and antioxidant into a reaction kettle, heat up to 180°C at a heating rate of 10°C / min under nitrogen protection to dehydrate until the distillate water volume reaches 95% of the theoretical value to complete esterification dehydration, and the flow rate of nitrogen is 5 L / min; Heat to 230°C for polycondensation reaction, and maintain the vacuum degree to -0.095 MPa until the acid value reaches 10 mg KOH / g to end; Keep this temperature and add CTBN for graft modification until the acid value reaches 33.1 mg KOH / g; Cool down to 160°C, add antioxidant and stir for 20 min and then discharge, and granulate the melt by underwater pelletizing to obtain the thermosetting polyester resin with a softening point of 114.5°C, an acid value of 32.9 mg KOH / g, and a viscosity (200°C) of 3.1 Pa·s.

[0071] The preparation method of the high-adhesion polyester resin powder coating in this example is as follows:

[0072] Mix the raw materials for preparing the high-adhesion polyester resin powder coating evenly by dry mixing in a high-speed mixer at 600 rpm for 5 min; Melt and extrude with a twin-screw extruder, with zone I at 85°C, zone II at 105°C, zone III at 115°C, and the screw speed of 350 rpm. During the melt extrusion process, vacuum degassing is required to -0.05 MPa; After pressing into tablets, cool with liquid nitrogen to -40°C, and screen to D90 = 30 μm to obtain the high-adhesion polyester resin powder coating.

[0073] Example 2

[0074] The difference between this example and Example 1 lies in:

[0075] The high-adhesion polyester resin powder coating in this example is composed of the following raw materials in parts by mass: 48 parts of thermosetting polyester resin, 4.3 parts of triglycidyl isocyanurate, 1.7 parts of blocked isocyanate, 2.8 parts of 2-hydroxyethyl methacrylate phosphate, 1.0 part of zirconate (tetrakis(triethanolamine) zirconate), 23 parts of barium sulfate, 8 parts of sericite powder, 0.7 part of fumed silica, and 1.7 parts of polytetrafluoroethylene wax;

[0076] Other raw materials, steps, and parameters are the same as those in Example 1.

[0077] Example 3

[0078] The difference between this example and Example 1 lies in:

[0079] The high-adhesion polyester resin powder coating of this example is composed of the following raw materials in parts by mass: 52 parts of thermosetting polyester resin, 4.0 parts of triglycidyl isocyanurate, 1.3 parts of blocked isocyanate, 3.5 parts of 2-hydroxyethyl methacrylate phosphate, 1.5 parts of zirconate, 25 parts of barium sulfate, 9 parts of sericite powder, 0.8 part of fumed silica, and 1.5 parts of polytetrafluoroethylene wax;

[0080] Other raw materials, steps and parameters are the same as those in Example 1.

[0081] Example 4

[0082] The difference between this example and Example 1 lies in:

[0083] The high-adhesion polyester resin powder coating of this example is composed of the following raw materials in parts by mass: 50 parts of thermosetting polyester resin, 4.5 parts of triglycidyl isocyanurate, 1.7 parts of blocked isocyanate, 5.5 parts of 2-hydroxyethyl methacrylate phosphate, 1.0 part of zirconate, 18 parts of barium sulfate, 12 parts of sericite powder, 1.5 parts of fumed silica, and 1.5 parts of polytetrafluoroethylene wax;

[0084] Other raw materials, steps and parameters are the same as those in Example 1.

[0085] Example 5

[0086] The difference between this example and Example 1 lies in:

[0087] The thermosetting polyester resin is composed of the following raw materials in parts by mass: 35 parts of PTA, 20 parts of IPA, 12 parts of NDA, 8 parts of AA, 65 parts of NPG, 12 parts of BEPD, 4 parts of TMP, 0.2 part of antioxidant (Irganox 1330), 2 parts of CTBN, and 0.05 part of catalyst.

[0088] Other raw materials, steps and parameters are the same as those in Example 1.

[0089] Example 6

[0090] The difference between this example and Example 1 lies in:

[0091] The thermosetting polyester resin is composed of the following raw materials in parts by mass: 40 parts of PTA, 18 parts of IPA, 20 parts of NDA, 5 parts of AA, 40 parts of NPG, 25 parts of BEPD, 5 parts of TMP, 0.3 part of antioxidant, 3 parts of CTBN, and 0.02 part of catalyst;

[0092] Other raw materials, steps and parameters are the same as those in Example 1.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 lies in:

[0095] The high-adhesion polyester resin powder coating of this comparative example is composed of the following raw materials in parts by mass: 50 parts of thermosetting polyester resin, 4.3 parts of triglycidyl isocyanurate, 1.5 parts of blocked isocyanate, 1.2 parts of zirconate, 27 parts of barium sulfate, 7 parts of sericite powder, 0.8 part of fumed silica, and 0.7 part of polytetrafluoroethylene wax; it does not contain 2-hydroxyethyl methacrylate phosphate;

[0096] Other raw materials, steps, and parameters are the same as those in Example 1.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 lies in:

[0099] The high-adhesion polyester resin powder coating of this comparative example is composed of the following raw materials in parts by mass: 50 parts of thermosetting polyester resin, 4.3 parts of triglycidyl isocyanurate, 1.3 parts of blocked isocyanate, 3.1 parts of 2-hydroxyethyl methacrylate phosphate, 1.1 parts of zirconate, 26 parts of barium sulfate, 7.5 parts of sericite powder, and 1.3 parts of polytetrafluoroethylene wax; it does not contain fumed silica;

[0100] Other raw materials, steps, and parameters are the same as those in Example 1.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 1 lies in:

[0103] The high-adhesion polyester resin powder coating of this comparative example is composed of the following raw materials in parts by mass: 50 parts of thermosetting polyester resin, 4.5 parts of triglycidyl isocyanurate, 1.5 parts of blocked isocyanate, 3.0 parts of 2-hydroxyethyl methacrylate phosphate, 23 parts of barium sulfate, 7 parts of sericite powder, 0.7 part of fumed silica, and 1.6 parts of polytetrafluoroethylene wax; it does not contain zirconate;

[0104] Other raw materials, steps, and parameters are the same as those in Example 1.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 1 lies in:

[0107] This thermosetting polyester resin is composed of the following raw materials in parts by mass: 40 parts of PTA, 22 parts of IPA, 8 parts of AA, 50 parts of NPG, 15 parts of BEPD, 5 parts of TMP, 2 parts of CTBN, 0.3 part of antioxidant, and 0.3 part of catalyst; it does not contain NDA;

[0108] Other raw materials, steps, and parameters are the same as those in Example 1.

[0109] Application Example

[0110] The high-adhesion polyester resin powder coating was electrostatically sprayed onto the surface of tinplate with a thickness of 0.3 mm that was not phosphated or chromated using a voltage of 60 kV, and the coating thickness was 70 μm. Subsequently, the sprayed tinplate specimens were cured at 180 °C for 15 min to obtain specimens with a high-adhesion polyester resin coating. The performance of each specimen was tested according to the methods listed in Table 1.

[0111]

[0112] The test results are shown in Table 2;

[0113]

[0114] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods. The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polyester resin powder coating with high adhesion, characterized in that, It includes the following raw materials: thermosetting polyester resin, triglycidyl isocyanurate, blocked isocyanate, 2-hydroxyethyl methacrylate phosphate, zirconate, barium sulfate, sericite powder, fumed silica and polytetrafluoroethylene wax; The thermosetting polyester resin includes the following raw materials in parts by mass: 25-50 parts of PTA, 10-30 parts of IPA, 3-18 parts of NDA, 3-12 parts of AA, 45-75 parts of NPG, 8-25 parts of BEPD, 2-10 parts of TMP, 1-6 parts of CTBN, 0.1-0.5 part of antioxidant and 0.005-0.1 part of catalyst; The preparation method of the thermosetting polyester resin includes the following steps: subjecting the raw materials of the thermosetting polyester resin except CTBN and antioxidant to esterification dehydration and polycondensation reaction; then adding CTBN for graft modification; adding antioxidant and discharging, and molding to obtain granular thermosetting polyester resin.

2. The high-adhesion polyester resin powder coating according to claim 1, characterized in that, The high-adhesion polyester resin powder coating includes the following raw materials for preparation in parts by mass: 45-60 parts of thermosetting polyester resin, 3.5-5.5 parts of triglycidyl isocyanurate, 1-2.5 parts of blocked isocyanate, 2-5 parts of 2-hydroxyethyl methacrylate phosphate, 0.5-2.0 parts of zirconate, 20-30 parts of barium sulfate, 5-12 parts of sericite powder, 0.5-1.2 parts of fumed silica and 1-2 parts of polytetrafluoroethylene wax.

3. The high-adhesion polyester resin powder coating according to claim 1, characterized in that The thermosetting polyester resin includes the following raw materials in parts by mass: 35-42 parts of PTA, 18-22 parts of IPA, 8-12 parts of NDA, 5-8 parts of AA, 55-65 parts of NPG, 12-18 parts of BEPD, 4-6 parts of TMP, 2-4 parts of CTBN, 0.1-0.3 part of antioxidant and 0.02-0.04 part of catalyst.

4. The high-adhesion polyester resin powder coating according to claim 1, characterized in that Meet at least one of the following conditions ①-②: ① The esterification dehydration is carried out by heating to 170-220°C at a heating rate of 5-15°C / min for dehydration until the distillate water volume reaches more than 85% of the theoretical value; ② The esterification dehydration needs to be carried out under nitrogen protection, and the nitrogen flow rate is 3-5 L / min.

5. The high-adhesion polyester resin powder coating according to claim 1, wherein Meet at least one of the following conditions ①-②: ① The temperature of the polycondensation reaction is 230-240°C; ② The polycondensation reaction is carried out until the acid value is 8-14 mg KOH / g.

6. The high-adhesion polyester resin powder coating according to claim 1, wherein, Meet at least one of the following conditions ①-③: ① The temperature of the graft modification is 230-240°C; ② The graft modification is carried out until the acid value is 30-36 mg KOH / g; ③ Before discharging, the temperature needs to be reduced to 160-180°C, and antioxidant is added and stirred for 15-30 min.

7. The high-adhesion polyester resin powder coating according to claim 1, wherein Meet at least one of the following conditions ①-⑦: ① The acid value of the 2-hydroxyethyl methacrylate phosphate is 250-310 mgKOH / g; ② The NCO content of the blocked isocyanate is 4-6%; ③ The zirconate is tetrabutyl zirconate or zirconate tetra(triethanolamine); ④ The D50 of the sericite powder is 10-20 μm; ⑤ The D98 of the barium sulfate is 2-5 μm; ⑥ The D50 of the polytetrafluoroethylene wax is 4-7 μm; ⑦ The nitrogen adsorption specific surface area of the fumed silica is 110~150 m 2 / g.

8. The preparation method of the high-adhesion polyester resin powder coating according to any one of claims 1 to 7, characterized in that, It includes the following steps: The raw materials for preparing the high-adhesion polyester resin powder coating are dry-mixed evenly and then melt-extruded, tableted, pulverized, and sieved to obtain the high-adhesion polyester resin powder coating.

9. The preparation method of the high adhesion polyester resin powder coating according to claim 8, characterized in that, Meet at least one of the following conditions ①~④: ① The rotation speed of the dry mixing is 500~800 rpm; ② The stirring time of the dry mixing is 3~8 min; ③ The melt extrusion uses a twin-screw extruder; ④ The temperature of the melt extrusion is 85~90 °C in zone I, 100~105 °C in zone II, and 110~115 °C in zone III.

10. The preparation method of the high adhesion polyester resin powder coating according to claim 8, characterized in that, Meet at least one of the following conditions ①~②: ① After tableting, it is also necessary to cool with liquid nitrogen to -40~-30 °C; ② The sieving is carried out until D90≤40 μm.

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