A kind of outdoor hydrolysis resistant polyester resin and its preparation method and application

Abstract

The invention relates to the technical field of polyester resins, and discloses an outdoor anti-hydrolysis polyester resin and a preparation method and application thereof. The outdoor anti-hydrolysis polyester resin comprises: 30-38 parts by weight of polyol, 48-50 parts by weight of dibasic acid, 20.5-28.5 parts by weight of acidolysis agent, and 0.1-0.12 parts by weight of onium salt curing accelerator; the invention uses 2-butyl-2-ethyl-1,3-propylene glycol as a polyol, introduces an alkyl side chain into a polyester molecule, generates steric hindrance and shielding effects, makes it difficult for water molecules to attack adjacent lipid bonds, and improves the hydrolysis resistance of the polyester resin. 2,2'-[(2-hydroxy-3-phenoxypropyl) azadiyl] diethanol contains a thermally stable benzene ring structure, is cross-linked into a polyester molecular chain, can increase the glass transition temperature of the polyester resin, improve heat resistance, and improve the boiling water resistance of the resin coating.

Description

Technical Field

[0001] The invention relates to the technical field of polyester resins, in particular to an outdoor hydrolysis-resistant polyester resin and a preparation method and application thereof. Background Art

[0002] Powder coatings have the characteristics of no VOC emissions, environmental protection, energy saving, high construction efficiency and wide application range. They are widely used in spraying of metal substrates, etc. However, due to the wider and wider application occasions, some outdoor products, such as architectural aluminum profiles, transportation facilities, outdoor furniture and garden facilities, have higher and higher requirements on the water resistance and boiling resistance of the coating.

[0003] The water resistance of the coating is related to the curing degree of the coating and the selected resin matrix, curing agent, etc. Polyester resin is widely used in powder coatings, and its molecular structure, active functional groups, etc. play a key role in the water resistance of the coating. Patent CN113817149B discloses the use of dimethyl adipate, 1,8-naphthalene dicarboxylic anhydride, and tetramethylethylene glycol to prepare a functional hydrophobic intermediate polymer by ester exchange, and then polymerize it with dodecyl hydroxystearic acid, terephthalic acid, neopentyl glycol, and isophthalic acid to obtain a water-resistant polyester resin for powder coating. However, the raw materials and preparation methods of the functional hydrophobic intermediate polymer are relatively complicated. And compared with this patent, the polyester resin obtained by cross-linking polyols, polyacids, etc. with a polyhydroxy cross-linking agent has better heat resistance, water resistance and other properties. Summary of the invention

[0004] The invention solves the problem that the polyester resin has poor water resistance and other properties.

[0005] Technical solution: An outdoor hydrolysis-resistant polyester resin comprises: 30-38 parts by weight of polyol, 48-50 parts by weight of dibasic acid, 20.5-28.5 parts by weight of acidolysis agent, 0.5-0.6 parts by weight of esterification catalyst, 0.5-0.6 parts by weight of antioxidant, and 0.1-0.12 parts by weight of onium salt curing accelerator.

[0006] Preferably, the polyol is any one or a combination of neopentyl glycol and 2-butyl-2-ethyl-1,3-propanediol;

[0007] Preferably, the acidolysis agent includes any one or a combination of isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and 2,2'-[(2-hydroxy-3-phenoxypropyl)azepinediyl]diethanol.

[0008] Preferably, the dibasic acid includes terephthalic acid. The esterification catalyst includes monobutyltin oxide. The antioxidant is any one or a combination of hindered phenol antioxidants and phosphite antioxidants. The onium salt curing accelerator includes triphenylethylphosphonium bromide.

[0009] Preferably, the preparation method of the outdoor resistant hydrolysis polyester resin is as follows: add polyol, dibasic acid and esterification catalyst to the reaction kettle in sequence, introduce nitrogen, heat up while stirring, first keep the temperature at 160-180°C for 1-2h, then heat up to 235-250°C, keep the temperature for 12-14h, discharge the water generated by the esterification reaction, add acidolysis agent when the acid value reaches 5-20 mg KOH / g, react for 3-4h; when the acid value reaches 50-70 mg KOH / g, vacuumize and carry out polycondensation reaction for 1-3h; when the acid value reaches 30-48mg KOH / g, add onium salt curing accelerator and antioxidant, stir for 20-40 min, discharge, cool and crush to obtain the outdoor resistant hydrolysis polyester resin.

[0010] Preferably, the preparation method of the 2,2'-[(2-hydroxy-3-phenoxypropyl)azepine diyl] diethanol is: add a solvent, 100 parts by weight of phenyl glycidyl ether, and 70-77 parts by weight of diethanolamine to a reaction container, heat to 40-50°C, stir and react for 3-5 hours, rotary evaporate, and separate the crude product by silica gel column chromatography, using dichloromethane and methanol solution as eluents to obtain 2,2'-[(2-hydroxy-3-phenoxypropyl)azepine diyl] diethanol. The reaction formula is:

[0011]

[0012] Preferably, the solvent is methanol, ethanol or tetrahydrofuran.

[0013] Preferably, the outdoor anti-hydrolysis polyester resin is used in a powder coating, which includes 53-55 parts by weight of the outdoor anti-hydrolysis polyester resin, 4.5-6 parts by weight of triglycidyl isocyanurate curing agent, 1.2-1.6 parts by weight of a leveling agent, 0.8-1.2 parts by weight of a defoamer, 0.8-1 parts by weight of a matting agent, 18-22 parts by weight of a filler, and 16-20 parts by weight of a pigment, wherein the matting agent includes benzoin, the filler includes barium sulfate, and the pigment includes titanium dioxide.

[0014] (III) Technical effect: The present invention uses 2-butyl-2-ethyl-1,3-propanediol as a polyol to synthesize a polyester resin with a dibasic acid, etc., and introduces an alkyl side chain into the polyester molecule to produce a steric hindrance and shielding effect, making it difficult for water molecules to attack adjacent lipid bonds, thereby improving the hydrolysis resistance of the polyester resin.

[0015] The present invention adds 2,2'-[(2-hydroxy-3-phenoxypropyl) azadiyl] diethanol, which contains three hydroxyl groups and can undergo a cross-linking reaction, thereby increasing the cross-linking density of the polyester resin, reducing the mobility of the molecule, making the lipid bond more difficult to hydrolyze, and containing a thermally stable benzene ring structure, which is cross-linked into the polyester molecular chain, thereby increasing the glass transition temperature of the polyester resin, improving the heat resistance, and improving the boiling water resistance of the resin coating.

[0016] The invention improves the hydrolysis resistance of the polyester resin by controlling the acid value, which not only avoids the acid value being too low so that the epoxy groups of the TGIC part do not participate in the reaction and reduce the crosslinking density of the polyester resin, but also prevents the acid value from being too high so that the hydrophilic -COOH remains and catalyzes the hydrolysis of the lipid bond. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1

[0019] (1) Add 20 mL of ethanol solvent, 2 g of phenyl glycidyl ether, and 1.48 g of diethanolamine to a reaction container, raise the temperature to 50°C, stir and react for 3 h, and rotary evaporate. The crude product is separated by silica gel column chromatography using dichloromethane and methanol solution as eluents to obtain 2,2'-[(2-hydroxy-3-phenoxypropyl)azepinediyl]diethanol.

[0020] (2) 30 g of neopentyl glycol, 8 g of 2-butyl-2-ethyl-1,3-propanediol, 50 g of terephthalic acid, and 0.5 g of esterification catalyst monobutyltin oxide were added to the reaction kettle in sequence, nitrogen was introduced, and the temperature was raised while stirring. The reaction was first kept at 180°C for 1 hour, and then the temperature was raised to 240°C and kept for 12 hours. The water generated by the esterification reaction was discharged. When the acid value reached 10 mg KOH / g, an acidolysis agent composed of 15 g of isophthalic acid, 5 g of 1,4-cyclohexanedicarboxylic acid, and 0.5 g of 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol was added and the reaction was continued for 4 hours. When the acid value reached 50 mg KOH / g, the polycondensation reaction was carried out under vacuum for 1 hour. When the acid value reached 40 mg KOH / g, add 0.1g triphenylethylphosphonium bromide curing accelerator, 0.29g hindered phenol antioxidant 1076, 0.21g phosphite antioxidant 168, stir for 20 min, discharge, cool and crush to obtain outdoor hydrolysis resistant polyester resin.

[0021] Example 2

[0022] (1) Add 30 mL of methanol solvent, 2 g of phenyl glycidyl ether, and 1.4 g of diethanolamine to a reaction container, raise the temperature to 40°C, stir and react for 5 h, and rotary evaporate. The crude product is separated by silica gel column chromatography using dichloromethane and methanol solution as eluents to obtain 2,2'-[(2-hydroxy-3-phenoxypropyl)azepinediyl]diethanol.

[0023] (2) 30 g of neopentyl glycol, 8 g of 2-butyl-2-ethyl-1,3-propanediol, 50 g of terephthalic acid, and 0.6 g of esterification catalyst monobutyltin oxide were added to the reaction kettle in sequence, nitrogen was introduced, and the temperature was raised while stirring. The reaction was first kept at 170°C for 2 h, and then the temperature was raised to 235°C and kept for 14 h. The water generated by the esterification reaction was discharged. When the acid value reached 5 mg KOH / g, an acidolysis agent composed of 17 g of isophthalic acid, 5 g of 1,4-cyclohexanedicarboxylic acid, and 1.5 g of 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol was added and the reaction was continued for 3 h. When the acid value reached 60 mg KOH / g, the polycondensation reaction was carried out under vacuum for 1 h. When the acid value reached 48 mg KOH / g, add 0.1g triphenylethylphosphonium bromide curing accelerator, 0.37g hindered phenol antioxidant 1076, 0.23g phosphite antioxidant 168, stir for 40 min, discharge, cool and crush to obtain outdoor hydrolysis resistant polyester resin.

[0024] Example 3

[0025] (1) Add 30 mL of tetrahydrofuran solvent, 2 g of phenyl glycidyl ether, and 1.54 g of diethanolamine to a reaction container, raise the temperature to 40°C, stir and react for 4 h, and rotary evaporate. The crude product is separated by silica gel column chromatography using dichloromethane and methanol solution as eluents to obtain 2,2'-[(2-hydroxy-3-phenoxypropyl)azepinediyl]diethanol.

[0026] (2) 30 g of neopentyl glycol, 8 g of 2-butyl-2-ethyl-1,3-propanediol, 48 g of terephthalic acid, and 0.5 g of esterification catalyst monobutyltin oxide were added to the reaction kettle in sequence, nitrogen was introduced, and the temperature was raised while stirring. The reaction was first kept at 160°C for 2 h, and then the temperature was raised to 250°C and kept for 12 h. The water generated by the esterification reaction was discharged. When the acid value reached 20 mg KOH / g, an acidolysis agent composed of 21 g of isophthalic acid, 5 g of 1,4-cyclohexanedicarboxylic acid, and 2.5 g of 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol was added and the reaction was continued for 4 h. When the acid value reached 70 mg KOH / g, the polycondensation reaction was carried out under vacuum for 3 h. When the acid value reached 30 mg KOH / g, the reaction was continued. KOH / g, add 0.12g triphenylethylphosphonium bromide curing accelerator, 0.37g hindered phenol antioxidant 1076, 0.23g phosphite antioxidant 168, stir for 20 min, discharge, cool and crush to obtain outdoor hydrolysis resistant polyester resin.

[0027] Comparative Example 1: The main difference between this comparative example and Example 1 is that 2-butyl-2-ethyl-1,3-propanediol is not added.

[0028] (1) 38 g of neopentyl glycol, 50 g of terephthalic acid, and 0.5 g of monobutyltin oxide, an esterification catalyst, were added to a reaction kettle in sequence, nitrogen was introduced, and the temperature was raised while stirring. The reaction was first kept at 180° C. for 1 h, and then the temperature was raised to 240° C. and kept for 12 h. The water generated by the esterification reaction was discharged. When the acid value reached 10 mg KOH / g, an acidolysis agent consisting of 15 g of isophthalic acid, 5 g of 1,4-cyclohexanedicarboxylic acid, and 0.5 g of 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol (prepared according to the method of Example 1) was added and the reaction was continued for 4 h. When the acid value reached 50 mg KOH / g, the polycondensation reaction was carried out under vacuum for 1 h. When the acid value reached 40 mgKOH / g, add 0.1g triphenylethylphosphonium bromide curing accelerator, 0.29g hindered phenol antioxidant 1076, and 0.21g phosphite antioxidant 168, stir for 20 min, discharge, cool, and crush to obtain polyester resin.

[0029] Comparative Example 2: The difference between this comparative example and Example 1 is that 2,2,4-trimethyl-1,3-pentanediol is used instead of 2-butyl-2-ethyl-1,3-propanediol.

[0030] (1) 30 g of neopentyl glycol, 8 g of 2,2,4-trimethyl-1,3-pentanediol, 50 g of terephthalic acid, and 0.5 g of esterification catalyst monobutyltin oxide were added to a reaction kettle in sequence, nitrogen was introduced, and the temperature was raised while stirring. The reaction was first kept at 180° C. for 1 hour, and then the temperature was raised to 240° C. and kept for 12 hours. The water generated by the esterification reaction was discharged. When the acid value reached 10 mg KOH / g, an acidolysis agent consisting of 15 g of isophthalic acid, 5 g of 1,4-cyclohexanedicarboxylic acid, and 0.5 g of 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol (prepared according to the method of Example 1) was added and the reaction was continued for 4 hours. When the acid value reached 50 mg KOH / g, vacuum was evacuated for condensation reaction for 1 hour. When the acid value reached 40 mg KOH / g, add 0.1g triphenylethylphosphonium bromide curing accelerator, 0.29g hindered phenol antioxidant 1076, 0.21g phosphite antioxidant 168, stir for 20 min, discharge, cool and crush to obtain polyester resin.

[0031] Comparative Example 3: The main difference between this comparative example and Example 1 is that hydroxypivalic acid neopentyl glycol monoester is used instead of 2-butyl-2-ethyl-1,3-propanediol.

[0032] (1) 30 g of neopentyl glycol, 8 g of hydroxypivalic acid neopentyl glycol monoester, 50 g of terephthalic acid, and 0.5 g of esterification catalyst monobutyl tin oxide were added to a reaction kettle in sequence, nitrogen was introduced, and the temperature was raised while stirring. The reaction was first kept at 180° C. for 1 hour, and then the temperature was raised to 240° C. and kept for 12 hours. The water generated by the esterification reaction was discharged. When the acid value reached 10 mg KOH / g, an acidolysis agent consisting of 15 g of isophthalic acid, 5 g of 1,4-cyclohexanedicarboxylic acid, and 0.5 g of 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol (prepared according to the method of Example 1) was added and the reaction was continued for 4 hours. When the acid value reached 50 mg KOH / g, the polycondensation reaction was carried out under vacuum for 1 hour. When the acid value reached 40 mg KOH / g, add 0.1g triphenylethylphosphonium bromide curing accelerator, 0.29g hindered phenol antioxidant 1076, 0.21g phosphite antioxidant 168, stir for 20 min, discharge, cool and crush to obtain polyester resin.

[0033] Comparative Example 4: The main difference between this comparative example and Example 1 is that 2,2'-[(2-hydroxy-3-phenoxypropyl)azepinediyl]diethanol is used instead of trimethylolpropane.

[0034] (1) Add 30g of neopentyl glycol, 8g of 2-butyl-2-ethyl-1,3-propanediol, 50g of terephthalic acid, and 0.5g of esterification catalyst monobutyltin oxide to a reactor in sequence, introduce nitrogen, and heat while stirring. First, keep the temperature at 180°C for 1h, then heat to 240°C and keep the temperature for 12h. Discharge the water generated by the esterification reaction. When the acid value reaches 10 mg KOH / g, add an acidolysis agent consisting of 15g of isophthalic acid, 5g of 1,4-cyclohexanedicarboxylic acid, and 0.5g of trimethylolpropane. React for 4h. When the acid value reaches 50 mg KOH / g, evacuate the reactor for condensation reaction for 1h. When the acid value reaches 40 mg KOH / g, add 0.1g triphenylethylphosphonium bromide curing accelerator, 0.29g hindered phenol antioxidant 1076, 0.21g phosphite antioxidant 168, stir for 20min, discharge, cool and crush to obtain polyester resin.

[0035] Refer to GB / T 6743-2008 standard to test the acid value of polyester resin.

[0036] The viscosity of the polyester resin was tested using a viscometer with the temperature set at 200°C. After the temperature stabilized, a polyester resin sample was taken and placed in the center of the test table of the viscometer for viscosity measurement.

[0037] The polyester sample was tested by differential scanning calorimetry. 10 mg of polyester resin sample was weighed and placed on the stage. After setting the parameters in the program, DSC measurement was performed. The measurement temperature range was 25-100°C and the heating rate was 10°C / min.

[0038] Table 1

[0039] Acid value (mg KOH / g) Viscosity (mPa.s) Glass transition temperature (℃) Example 1 34.9 5594 70.4 Example 2 35.4 5621 74.1 Example 3 35.2 5649 73.5 Comparative Example 1 35.7 6173 71.2 Comparative Example 2 36.0 5795 70.6 Comparative Example 3 34.7 5610 69.0 Comparative Example 4 35.1 5526 64.8

[0040] After testing, the polyester resins prepared in each embodiment have moderate acid value and viscosity value. In addition, embodiments 1-3 and comparative examples 1-3 have higher glass transition temperatures, mainly because 2,2'-[(2-hydroxy-3-phenoxypropyl) azadiyl] diethanol contains a thermally stable benzene ring structure, which is cross-linked into the polyester molecular chain, thereby increasing the glass transition temperature of the polyester resin and improving the heat resistance.

[0041] Example 4: 530 g of outdoor hydrolysis-resistant polyester resin (prepared according to the method of Example 1), 12 g of leveling agent BYK-354, 8 g of defoaming agent Ruike RP-6403, 10 g of matting agent benzoin, 180 g of filler barium sulfate, and 200 g of pigment titanium dioxide were stirred and mixed, and then 45 g of triglycidyl isocyanurate curing agent was added to obtain a powder coating.

[0042] Example 5: 560 g of outdoor hydrolysis-resistant polyester resin (prepared according to the method of Example 1), 16 g of leveling agent BYK-354, 12 g of defoaming agent Ruike RP-6403, 8 g of matting agent benzoin, 220 g of filler barium sulfate, and 160 g of pigment titanium dioxide were stirred and mixed, and then 60 g of triglycidyl isocyanurate curing agent was added to obtain a powder coating.

[0043] Comparative Example 5: 530 g of polyester resin (prepared according to the method of Comparative Example 1), 12 g of leveling agent BYK-354, 8 g of defoaming agent Ruike RP-6403, 10 g of matting agent benzoin, 180 g of filler barium sulfate, and 200 g of pigment titanium dioxide were stirred and mixed, and then 45 g of triglycidyl isocyanurate curing agent was added to obtain a powder coating.

[0044] Comparative Example 6: 530 g of polyester resin (prepared according to the method of Comparative Example 2), 12 g of leveling agent BYK-354, 8 g of defoaming agent Ruike RP-6403, 10 g of matting agent benzoin, 180 g of filler barium sulfate, and 200 g of pigment titanium dioxide were stirred and mixed, and then 45 g of triglycidyl isocyanurate curing agent was added to obtain a powder coating.

[0045] Comparative Example 7: 530 g of polyester resin (prepared according to the method of Comparative Example 3), 12 g of leveling agent BYK-354, 8 g of defoaming agent Ruike RP-6403, 10 g of matting agent benzoin, 180 g of filler barium sulfate, and 200 g of pigment titanium dioxide were stirred and mixed, and then 45 g of triglycidyl isocyanurate curing agent was added to obtain a powder coating.

[0046] Comparative Example 8: 530 g of polyester resin (prepared according to the method of Comparative Example 4), 12 g of leveling agent BYK-354, 8 g of defoaming agent Ruike RP-6403, 10 g of matting agent benzoin, 180 g of filler barium sulfate, and 200 g of pigment titanium dioxide were stirred and mixed, and then 45 g of triglycidyl isocyanurate curing agent was added to obtain a powder coating.

[0047] The powder coating is extruded, sheeted, and crushed through a twin-screw extruder, then passed through a 200-mesh sieve, and then sprayed on the substrate by electrostatic spraying and cured at 200°C for 10 minutes. The boiling water immersion test is tested according to GB / T 1733-1993 standard, and the boiling water is boiled for 72-96 hours.

[0048] Table 2

[0049]

[0050] After the boiling test, the powder coatings of Examples 4 and 5 have better boiling and hydrolysis resistance. This is mainly because the polyester resin synthesized with 2-butyl-2-ethyl-1,3-propanediol as the polyol introduces the alkyl side chain into the polyester molecular chain, which can produce steric hindrance and shielding effects, making it difficult for water molecules to attack adjacent lipid bonds, thereby improving the hydrolysis resistance of the polyester resin. At the same time, 2,2'-[(2-hydroxy-3-phenoxypropyl) azadiyl] diethanol is added to introduce a thermally stable benzene ring structure, which improves the heat resistance of the polyester resin and is conducive to improving the boiling water resistance of the resin coating.

[0051] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An outdoor hydrolysis-resistant polyester resin, characterized in that: The outdoor hydrolysis-resistant polyester resin comprises: 30-38 parts by weight of polyol, 48-50 parts by weight of dibasic acid, 20.5-28.5 parts by weight of acidolysis agent, 0.5-0.6 parts by weight of esterification catalyst, 0.5-0.6 parts by weight of antioxidant, and 0.1-0.12 parts by weight of onium salt curing accelerator; The polyol is a combination of neopentyl glycol and 2-butyl-2-ethyl-1,3-propanediol; The acidolysis agent is a combination of isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and 2,2'-[(2-hydroxy-3-phenoxypropyl)azadiyl]diethanol; The preparation method of 2,2'-[(2-hydroxy-3-phenoxypropyl)azepine diyl]diethanol is as follows: add a solvent, phenyl glycidyl ether and diethanolamine into a reaction container, raise the temperature to 40-50°C, stir the reaction for 3-5h, rotary evaporate, and separate the crude product by silica gel column chromatography to obtain 2,2'-[(2-hydroxy-3-phenoxypropyl)azepine diyl]diethanol.

2. The outdoor hydrolysis-resistant polyester resin according to claim 1, characterized in that: The dibasic acid is terephthalic acid.

3. The outdoor hydrolysis-resistant polyester resin according to claim 1, characterized in that: The esterification catalyst is monobutyltin oxide, and the onium salt curing accelerator is triphenylethylphosphonium bromide.

4. The outdoor hydrolysis-resistant polyester resin according to claim 1, characterized in that: The antioxidant is any one or a combination of hindered phenol antioxidants and phosphite antioxidants.

5. The outdoor hydrolysis-resistant polyester resin according to claim 1, characterized in that: The solvent is methanol, ethanol or tetrahydrofuran.

6. The outdoor hydrolysis-resistant polyester resin according to claim 1, characterized in that: The amount of phenyl glycidyl ether used is 100 parts by weight, and the amount of diethanolamine used is 70-77 parts by weight.

7. A method for preparing an outdoor hydrolysis-resistant polyester resin according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: adding polyol, dibasic acid and esterification catalyst to a reaction kettle in sequence, introducing nitrogen, raising the temperature while stirring, firstly keeping the temperature at 160-180°C for 1-2h, then raising the temperature to 235-250°C, keeping the temperature for 12-14h, discharging water generated by the esterification reaction, adding an acidolysis agent when the acid value reaches 5-20 mg KOH / g, and reacting for 3-4h; when the acid value reaches 50-70 mg KOH / g, vacuumizing for condensation reaction for 1-3h; when the acid value reaches 30-48 mg KOH / g, adding an onium salt curing accelerator and an antioxidant, stirring for 20-40 min, discharging, cooling and crushing to obtain an outdoor anti-hydrolysis polyester resin.

8. Use of the outdoor hydrolysis resistant polyester resin according to any one of claims 1 to 6 or the outdoor hydrolysis resistant polyester resin prepared by the preparation method according to claim 7 in powder coatings, characterized in that: The powder coating comprises 53-55 parts by weight of outdoor hydrolysis-resistant polyester resin, 4.5-6 parts by weight of triglycidyl isocyanurate curing agent, 1.2-1.6 parts by weight of leveling agent, 0.8-1.2 parts by weight of defoaming agent, 0.8-1 parts by weight of matting agent, 18-22 parts by weight of filler and 16-20 parts by weight of pigment.

9. The use according to claim 8, characterized in that: The matting agent includes benzoin, the filler includes barium sulfate, and the pigment includes titanium dioxide.

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