CN114316233A - Polyester resin with excellent ozone oxidation resistance and high and low temperature performance and preparation method thereof - Google Patents
Polyester resin with excellent ozone oxidation resistance and high and low temperature performance and preparation method thereof Download PDFInfo
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Abstract
The invention relates to the technical field of powder coatings, in particular to a polyester resin for powder with excellent ozone oxidation resistance and high and low temperature performance and a preparation method thereof, wherein the polyester resin is obtained by polymerizing bisphenol A, 4' -dichlorodiphenyl sulfone, N-dimethylformamide, adipic acid, isophthalic acid, neopentyl glycol, thionyl chloride, 1, 4-cyclohexanedicarboxylic acid and the like which are used as main raw materials. Firstly, bisphenol A and 4, 4' -dichlorodiphenyl sulfone are polymerized to obtain bisphenol A terminated micromolecule polysulfone, and then the micromolecule polysulfone is polymerized to obtain the polyester resin. The polyester resin molecule contains block micromolecule polysulfone chain segments, 1, 4-cyclohexanedicarboxylic acid and the like, is finally used in powder coating of TGIC curing system, and can obtain a coating film with excellent ozone oxidation resistance and high and low temperature performance.
Description
Technical Field
The invention belongs to the technical field of powder coatings, and particularly relates to a polyester resin with excellent ozone oxidation resistance and high and low temperature performance, a preparation method thereof, and application thereof in preparing powder coatings.
Background
Different from oil paint and water paint, the powder paint is solid powder without organic solvent, and is a novel environment-friendly paint which is uniformly coated on the surface of a workpiece by taking air as a dispersing medium instead of solvent or water as the dispersing medium during coating and forms a coating film with special application after heating. The powder coating has good protective performance and decorative performance, but the powder coating is widely applied in the current traditional coating industry, such as the coating of guardrails of highways, air-conditioning outdoor units, indoor metal tables and chairs and the like, along with the increasing popularization range, some special chemical equipment is also coated by the powder coating, such as ozone generating equipment, outdoor oxidation resistance testing equipment, power generation piles and supporting columns for wind power generator solar power generation on Gobi deserts and the like, the special equipment has higher requirement on oxidation resistance, and the wind power generation is in special outdoor areas throughout the year, besides oxidation, the difference of high and low temperature in all seasons is huge, for example, the temperature difference of all seasons on Gobi deserts reaches about 80 ℃, and a special powder coating is required to be capable of achieving oxidation resistance and simultaneously have excellent high and low temperature resistance. Because the polyester resin used by the common polyester powder coating is mostly polymerized by common terephthalic acid, adipic acid, diethylene glycol, ethylene glycol and the like, the finally formed coating film has defects in both durable oxidation resistance and high and low temperature performance, and cannot meet the application requirements of the special fields.
Aiming at the problems, the invention provides a novel polyester resin system, wherein the polyester resin molecular system contains a segmented micromolecular polysulfone chain segment, 1, 4-cyclohexanedicarboxylic acid and the like, is finally used in powder coating of a TGIC curing system, can obtain a coating film with excellent ozone oxidation resistance and high and low temperature performance, and can meet the application requirements of the powder coating with other conventional performances.
Disclosure of Invention
The present invention provides a polyester resin system obtained by polymerization using bisphenol a, 4' -dichlorodiphenylsulfone, N-Dimethylformamide (DMF), adipic acid, isophthalic acid, neopentyl glycol, thionyl chloride, 1, 4-cyclohexanedicarboxylic acid, etc. as main raw materials. Firstly, bisphenol A, 4' -dichlorodiphenyl sulfone and the like are polymerized to obtain bisphenol A terminated micromolecule polysulfone, and then the bisphenol A terminated micromolecule polysulfone is polymerized to obtain the polyester resin. The polyester resin molecule contains a segmented micromolecule polysulfone chain segment, 1, 4-cyclohexanedicarboxylic acid and the like, is finally used in powder coating of a TGIC curing system, can obtain a coating film with excellent ozone oxidation resistance and high and low temperature performance, and the cured coating film has good appearance, luster and boiling water resistance, good impact resistance, wear resistance and the like and excellent comprehensive performance.
The polyester resin for powder with good ozone oxidation resistance and high and low temperature performance is characterized by comprising the following main raw materials in a molar ratio:
the auxiliary materials comprise sodium hydroxide aqueous solution, a catalyst, an antioxidant and hydrochloric acid.
Preferably, the polymerization reaction system comprises a catalyst of monobutyl tin oxide, and the amount of the catalyst is 0.08-0.2% of the total molar amount of the main raw materials;
preferably, the polymerization reaction system comprises an antioxidant 1010 (pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) ] which is used in an amount of 0.2-0.5% of the total molar amount of the main raw materials.
Preferably, the raw material also comprises 30-40% of sodium hydroxide aqueous solution by mass fraction; the dosage of the sodium hydroxide is 2.05-2.1:1 of the molar ratio of the bisphenol A;
preferably, the raw materials also comprise 28-31% of hydrochloric acid aqueous solution in percentage by mass;
preferably, the molar amount of bisphenol A is 1.1 to 1.2 times that of 4, 4' -dichlorodiphenyl sulfone.
A method for preparing the above polyester resin, comprising the steps of:
A. adding the adipic acid with the formula amount into a reactor 1, then dropwise adding thionyl chloride for stirring, carrying out reflux reaction after dropwise adding is finished, decompressing and removing excessive thionyl chloride after a system forms a transparent homogeneous phase to obtain adipoyl chloride, and storing for later use;
B. adding a sodium hydroxide aqueous solution with a formula amount into a reactor 2, stirring and adding bisphenol A in batches (preferably 4-6 batches) for full reaction; after the bisphenol A is completely added, carrying out heat preservation reaction at the temperature of 50-60 ℃;
C. sampling and detecting the amount of free bisphenol A by using a liquid phase, stopping the reaction when the content of the free bisphenol A is lower than 0.5 percent, starting vacuum (preferably, the vacuum degree is controlled between-0.097 Mpa and-0.099 Mpa), heating to 80-85 ℃, and removing water in a reaction system under reduced pressure;
D. when the water content in the system is lower than 1 percent, adding DMF and 4, 4' -dichlorodiphenyl sulfone according to the formula ratio, uniformly mixing, heating to 140-145 ℃, and carrying out heat preservation reaction;
E. detecting by liquid chromatography, stopping reaction when the content of free 4, 4' -dichlorodiphenyl sulfone is lower than 1%, cooling to room temperature, adding hydrochloric acid solution to adjust the pH value to 6-6.5, and fully stirring to convert the end group into phenolic hydroxyl; then carrying out suction filtration at room temperature, and removing generated sodium chloride to obtain DMF filtrate containing micromolecule polysulfone;
F. adding the filtrate into a polyester synthesis reactor 3, heating to 130-135 ℃, carrying out full dehydration treatment (preferably, the water content in the reaction system is lower than 0.5%), cooling to 40-50 ℃, adding a catalyst of monobutyl tin oxide according to the formula amount, uniformly stirring, dropwise adding adipoyl chloride generated in the reactor 1, and continuing to carry out heat preservation chain extension reaction after dropwise adding is finished;
G. sampling and testing a hydroxyl value, adding isophthalic acid and neopentyl glycol in a formula amount when the hydroxyl value is lower than 2mgKOH/g, gradually heating to 210-220 ℃ for carrying out heat preservation polymerization reaction (preferably at a heating rate of 15-18 ℃/h), and simultaneously removing a DMF solvent in the heating process;
H. when the acid value is reduced to 10mgKOH/g, adding 1, 4-cyclohexanedicarboxylic acid with the formula amount to carry out end-capping reaction, gradually heating to 230 +/-5 ℃ (preferably the heating rate of 5-7 ℃/h), and carrying out heat preservation reaction;
I. and adding antioxidant 1010 in a formula amount when the acid value of the polymer reaches 30-37mgKOH/g, uniformly mixing, cooling, discharging, cooling the polyester resin, and crushing and granulating to obtain the polyester resin.
The polyester resin finally obtained is light yellow transparent particles, the acid value is 30-37mgKOH/g, the softening point: 120 ℃ and 130 ℃.
The invention also relates to the use of the above polyester resin for TGIC cured polyester powder coatings.
The technical effects of the invention are as follows: the product of the invention has the advantages that through the synergy of all components, especially the introduction of special micromolecule polysulfone chain segments (bisphenol A terminated micromolecule polysulfone is obtained by polymerizing bisphenol A and 4, 4' -dichlorodiphenyl sulfone), the obtained polyester resin and TGIC cured coating film has good appearance, luster and boiling water boiling resistance, and common impact resistance, especially low temperature resistance and impact resistance, the impact resistance of the coating film can still smoothly pass through after 40 ℃/4h, the coating film has almost no change in high temperature conditions such as 180 ℃/128h for a long time, the lasting high temperature resistance is good, meanwhile, the wear resistance can reach about 4.21L/mum, the performance is good, and the comprehensive performance is good.
Detailed Description
The present invention will be further described with reference to specific examples so that those skilled in the art may better understand the present invention, but the present invention is not limited thereto.
Example 1
The polyester resin for powder has good ozone oxidation resistance and high and low temperature performance, and the polyester resin comprises the following raw materials:
the polymerization reaction system further comprises a catalyst of monobutyl tin oxide, and the using amount of the monobutyl tin oxide is 0.1 percent of the total molar amount of the raw materials; antioxidant 1010 (pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) ] in an amount of 0.2% based on the total molar amount of the above raw materials.
The raw material also comprises a sodium hydroxide aqueous solution with the mass fraction of 35%; the molar ratio of the sodium hydroxide to the bisphenol A is 2: 1;
the raw material also comprises a hydrochloric acid aqueous solution with the mass fraction of 30%.
A process for preparing a polyester resin comprising the steps of:
A. adding adipic acid with the formula amount into a reactor 1, then dropwise adding thionyl chloride, starting stirring, after dropwise adding within 1h, performing reflux reaction for 3h at the boiling point of the thionyl chloride, after the system completely forms a transparent homogeneous phase, removing excessive thionyl chloride under reduced pressure to obtain adipoyl chloride, and sealing and storing for later use;
B. adding a sodium hydroxide aqueous solution with a formula amount into a reactor 2, starting stirring, and then adding bisphenol A in 6 batches for full neutralization reaction at an interval of 30 min; after the bisphenol A is completely added, carrying out heat preservation reaction at 60 ℃;
C. sampling and detecting the amount of free bisphenol A by using a liquid phase, stopping reaction when the content of the free bisphenol A is lower than 0.5 percent, starting vacuum, controlling the vacuum degree at-0.097 Mpa, heating to 85 ℃, and removing water in a reaction system under reduced pressure;
D. when the water content in the system is lower than 1%, adding DMF and 4, 4' -dichlorodiphenyl sulfone according to the formula ratio, uniformly mixing, heating to 145 ℃, and carrying out heat preservation reaction;
E. detecting by liquid chromatography, stopping reaction when the content of free 4, 4' -dichlorodiphenyl sulfone is lower than 1%, cooling to room temperature, adding hydrochloric acid solution to adjust the pH value to 6.5, and fully stirring for 1h to convert the sodium phenolate at the end group into phenolic hydroxyl; then carrying out suction filtration at room temperature to remove the generated sodium chloride, and obtaining DMF filtrate containing micromolecule polysulfone;
F. adding the filtrate into a polyester synthesis reactor 3, heating to 135 ℃, carrying out full dehydration treatment, cooling to 50 ℃ when the water content in a reaction system is lower than 0.5%, adding a catalyst of monobutyl tin oxide in a formula amount, uniformly stirring, dropwise adding adipoyl chloride generated in the reaction step 1, finishing the addition within 2 hours, and then continuing to carry out heat preservation chain extension reaction;
G. sampling and testing a hydroxyl value, when the hydroxyl value is lower than 2mgKOH/g, indicating that the phenolic hydroxyl group basically finishes reacting, adding m-phthalic acid and neopentyl glycol according to the formula amount, gradually heating to 220 ℃ at a heating rate of 15 ℃/h for carrying out heat preservation polymerization reaction, and simultaneously removing a DMF solvent in the heating process;
H. when the acid value is reduced to 10mgKOH/g, adding 1, 4-cyclohexanedicarboxylic acid with the formula amount to carry out end capping reaction, gradually heating to 230 ℃ at the heating rate of 5 ℃/h, and carrying out heat preservation reaction;
I. adding antioxidant 1010 in a formula amount when the acid value of the polymer reaches 35mgKOH/g, uniformly mixing, cooling to about 200 ℃, discharging at high temperature while the mixture is hot, cooling the polyester resin by using a steel belt with condensed water, and crushing and granulating to obtain the polyester resin.
The polyester resin prepared in this example was determined to be light yellow transparent particles, having an acid value of 34mgKOH/g, a softening point: 123 ℃ is adopted.
Example 2
The polyester resin for powder has good ozone oxidation resistance and high and low temperature performance, and the polyester resin comprises the following raw materials:
the polymerization reaction system further comprises a catalyst of monobutyl tin oxide, and the using amount of the monobutyl tin oxide is 0.1 percent of the total molar amount of the raw materials; antioxidant 1010 (pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) ] in an amount of 0.2% based on the total molar amount of the above raw materials.
The raw material also comprises a sodium hydroxide aqueous solution with the mass fraction of 40%; the molar ratio of the sodium hydroxide to the bisphenol A is 2: 1;
the raw material also comprises a hydrochloric acid aqueous solution with the mass fraction of 28%.
A process for preparing a polyester resin comprising the steps of:
A. adding adipic acid with the formula amount into a reactor 1, then dropwise adding thionyl chloride, starting stirring, after dropwise adding within 1h, performing reflux reaction for 3h at the boiling point of the thionyl chloride, after the system completely forms a transparent homogeneous phase, removing excessive thionyl chloride under reduced pressure to obtain adipoyl chloride, and sealing and storing for later use;
B. adding a sodium hydroxide aqueous solution with a formula amount into a reactor 2, starting stirring, and then adding bisphenol A in 6 batches for full neutralization reaction at an interval of 30 min; after the bisphenol A is completely added, carrying out heat preservation reaction at 55 ℃;
C. sampling and detecting the amount of free bisphenol A by using a liquid phase, stopping reaction when the content of the free bisphenol A is lower than 0.5%, starting vacuum, controlling the vacuum degree to be 0.099Mpa, heating to 80 ℃, and removing water in a reaction system under reduced pressure;
D. when the water content in the system is lower than 1%, adding DMF and 4, 4' -dichlorodiphenyl sulfone according to the formula ratio, uniformly mixing, heating to 140 ℃, and carrying out heat preservation reaction;
E. detecting by liquid chromatography, stopping reaction when the content of free 4, 4' -dichlorodiphenyl sulfone is lower than 1%, cooling to room temperature, adding hydrochloric acid solution to adjust the pH value to 6, and fully stirring for 1h to convert the sodium phenolate at the end group into phenolic hydroxyl; then carrying out suction filtration at room temperature to remove the generated sodium chloride, and obtaining DMF filtrate containing micromolecule polysulfone;
F. adding the filtrate into a polyester synthesis reactor 3, heating to 132 ℃, carrying out full dehydration treatment, cooling to 40 ℃ when the water content in a reaction system is lower than 0.5%, adding a catalyst of monobutyl tin oxide in a formula amount, uniformly stirring, dropwise adding adipoyl chloride generated in the reaction step 1, finishing the addition within 2 hours, and then continuing to carry out heat preservation chain extension reaction;
G. sampling and testing a hydroxyl value, when the hydroxyl value is lower than 2mgKOH/g, indicating that the phenolic hydroxyl group basically finishes reacting, adding m-phthalic acid and neopentyl glycol according to the formula amount, gradually heating to 220 ℃ at a heating rate of 18 ℃/h for carrying out heat preservation polymerization reaction, and simultaneously removing a DMF solvent in the heating process;
H. when the acid value is reduced to 10mgKOH/g, adding 1, 4-cyclohexanedicarboxylic acid with the formula amount to carry out end capping reaction, gradually heating to 230 ℃ at the heating rate of 6 ℃/h, and carrying out heat preservation reaction;
I. adding antioxidant 1010 in a formula amount when the acid value of the polymer reaches 35mgKOH/g, uniformly mixing, cooling to about 200 ℃, discharging at high temperature while the mixture is hot, cooling the polyester resin by using a steel belt with condensed water, and crushing and granulating to obtain the polyester resin.
The polyester resin prepared in this example was determined to be light yellow transparent particles, having an acid value of 35mgKOH/g, a softening point: 125 ℃.
Example 3
The polyester resin for powder has good ozone oxidation resistance and high and low temperature performance, and the polyester resin comprises the following raw materials:
the polymerization reaction system further comprises a catalyst of monobutyl tin oxide, and the using amount of the monobutyl tin oxide is 0.1 percent of the total molar amount of the raw materials; antioxidant 1010 (pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) ] in an amount of 0.2% based on the total molar amount of the above raw materials.
The raw material also comprises a sodium hydroxide aqueous solution with the mass fraction of 30%; the molar ratio of the sodium hydroxide to the bisphenol A is 2: 1;
the raw materials also comprise a hydrochloric acid aqueous solution with the mass fraction of 31%.
A process for preparing a polyester resin comprising the steps of:
A. adding adipic acid with the formula amount into a reactor 1, then dropwise adding thionyl chloride, starting stirring, after dropwise adding within 1h, performing reflux reaction for 2h at the boiling point of the thionyl chloride, after the system completely forms a transparent homogeneous phase, removing excessive thionyl chloride under reduced pressure to obtain adipoyl chloride, and sealing and storing for later use;
B. adding a sodium hydroxide aqueous solution with a formula amount into a reactor 2, starting stirring, and then adding bisphenol A in 6 batches for full neutralization reaction at an interval of 30 min; after the bisphenol A is completely added, carrying out heat preservation reaction at 50 ℃;
C. sampling and detecting the amount of free bisphenol A by using a liquid phase, stopping reaction when the content of the free bisphenol A is lower than 0.5 percent, starting vacuum, controlling the vacuum degree at-0.099 Mpa, heating to 85 ℃, and removing water in a reaction system under reduced pressure;
D. when the water content in the system is lower than 1%, adding DMF and 4, 4' -dichlorodiphenyl sulfone according to the formula ratio, uniformly mixing, heating to 142 ℃, and carrying out heat preservation reaction;
E. detecting by liquid chromatography, stopping reaction when the content of free 4, 4' -dichlorodiphenyl sulfone is lower than 1%, cooling to room temperature, adding hydrochloric acid solution to adjust the pH value to 6.5, and fully stirring for 1h to convert the sodium phenolate at the end group into phenolic hydroxyl; then carrying out suction filtration at room temperature to remove the generated sodium chloride, and obtaining DMF filtrate containing micromolecule polysulfone;
F. adding the filtrate into a polyester synthesis reactor 3, heating to 135 ℃, carrying out full dehydration treatment, cooling to 40 ℃ when the water content in a reaction system is lower than 0.5%, adding a catalyst of monobutyl tin oxide in a formula amount, uniformly stirring, dropwise adding adipoyl chloride generated in the reaction step 1, finishing the addition within 2 hours, and then continuing to carry out heat preservation chain extension reaction;
G. sampling and testing a hydroxyl value, when the hydroxyl value is lower than 2mgKOH/g, indicating that the phenolic hydroxyl group basically finishes reacting, adding m-phthalic acid and neopentyl glycol according to the formula amount, gradually heating to 220 ℃ at a heating rate of 15 ℃/h for carrying out heat preservation polymerization reaction, and simultaneously removing a DMF solvent in the heating process;
H. when the acid value is reduced to 10mgKOH/g, adding 1, 4-cyclohexanedicarboxylic acid with the formula amount to carry out end capping reaction, gradually heating to 230 ℃ at the heating rate of 5 ℃/h, and carrying out heat preservation reaction;
I. adding antioxidant 1010 in a formula amount when the acid value of the polymer reaches 35mgKOH/g, uniformly mixing, cooling to about 200 ℃, discharging at high temperature while the mixture is hot, cooling the polyester resin by using a steel belt with condensed water, and crushing and granulating to obtain the polyester resin.
The polyester resin prepared in this example was determined to be light yellow transparent particles, having an acid value of 36mgKOH/g, a softening point: 125 ℃.
Example 4
The polyester resin for powder has good ozone oxidation resistance and high and low temperature performance, and the polyester resin comprises the following raw materials:
the polymerization reaction system further comprises a catalyst of monobutyl tin oxide, and the using amount of the monobutyl tin oxide is 0.1 percent of the total molar amount of the raw materials; antioxidant 1010 (pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) ] in an amount of 0.2% based on the total molar amount of the above raw materials.
The raw material also comprises a sodium hydroxide aqueous solution with the mass fraction of 30%; the molar ratio of the sodium hydroxide to the bisphenol A is 2: 1;
the raw material also comprises a hydrochloric acid aqueous solution with the mass fraction of 30%.
A process for preparing a polyester resin comprising the steps of:
A. adding adipic acid with the formula amount into a reactor 1, then dropwise adding thionyl chloride, starting stirring, after dropwise adding within 1h, performing reflux reaction for 2h at the boiling point of the thionyl chloride, after the system completely forms a transparent homogeneous phase, removing excessive thionyl chloride under reduced pressure to obtain adipoyl chloride, and sealing and storing for later use;
B. adding a sodium hydroxide aqueous solution with a formula amount into a reactor 2, starting stirring, and then adding bisphenol A in 6 batches for full neutralization reaction at an interval of 30 min; after the bisphenol A is completely added, carrying out heat preservation reaction at 50 ℃;
C. sampling and detecting the amount of free bisphenol A by using a liquid phase, stopping reaction when the content of the free bisphenol A is lower than 0.5 percent, starting vacuum, controlling the vacuum degree at-0.097 Mpa, heating to 85 ℃, and removing water in a reaction system under reduced pressure;
D. when the water content in the system is lower than 1%, adding DMF and 4, 4' -dichlorodiphenyl sulfone according to the formula ratio, uniformly mixing, heating to 142 ℃, and carrying out heat preservation reaction;
E. detecting by liquid chromatography, stopping reaction when the content of free 4, 4' -dichlorodiphenyl sulfone is lower than 1%, cooling to room temperature, adding hydrochloric acid solution to adjust the pH value to 6.5, and fully stirring for 1h to convert the sodium phenolate at the end group into phenolic hydroxyl; then carrying out suction filtration at room temperature to remove the generated sodium chloride, and obtaining DMF filtrate containing micromolecule polysulfone;
F. adding the filtrate into a polyester synthesis reactor 3, heating to 135 ℃, carrying out full dehydration treatment, cooling to 45 ℃ when the water content in a reaction system is lower than 0.5%, adding a catalyst of monobutyl tin oxide in a formula amount, uniformly stirring, dropwise adding adipoyl chloride generated in the reaction step 1, finishing the addition within 2 hours, and then continuing to carry out heat preservation chain extension reaction;
G. sampling and testing a hydroxyl value, when the hydroxyl value is lower than 2mgKOH/g, indicating that the phenolic hydroxyl group basically finishes reacting, adding m-phthalic acid and neopentyl glycol according to the formula amount, gradually heating to 215 ℃ at the heating rate of 16 ℃/h for carrying out heat preservation polymerization reaction, and simultaneously removing a DMF solvent in the heating process;
H. when the acid value is reduced to 10mgKOH/g, adding 1, 4-cyclohexanedicarboxylic acid with the formula amount to carry out end capping reaction, gradually heating to 230 ℃ at the heating rate of 6 ℃/h, and carrying out heat preservation reaction;
I. adding antioxidant 1010 in a formula amount when the acid value of the polymer reaches 35mgKOH/g, uniformly mixing, cooling to about 200 ℃, discharging at high temperature while the mixture is hot, cooling the polyester resin by using a steel belt with condensed water, and crushing and granulating to obtain the polyester resin.
The polyester resin prepared in this example was determined to be light yellow transparent particles, having an acid value of 36mgKOH/g, a softening point: 127 ℃.
Comparative example 1: polyester resin for commercial ordinary TGIC curing system, acid value: 32mgKOH/g, softening point 115 ℃, model GH-2200, available from Zhejiang Guanghua New materials GmbH.
Application performance test comparison:
the formulation of TGIC system curable polyester powder coating formulations for polyester resins of the invention is generally as follows in parts by weight (wherein the polyester resins are obtained from the above examples and comparative examples, respectively):
preparing a coating layer: and uniformly mixing the materials according to the formula requirements of the TGIC system powder coating, extruding, tabletting and crushing the materials by using a double-screw extruder, and then crushing and sieving the tablets to prepare the powder coating. The powder coating is sprayed on the galvanized iron substrate after surface treatment by an electrostatic spray gun, the film thickness is about 80 mu m, and then the powder coating is baked and cured at 200 ℃/10min to obtain the coating.
The detection of the coating index is based on GB/T21776 2008 'Standard guide for powder coating and coating detection'; the wear resistance test is carried out according to GB/T23988-; the ozone oxidation resistance is tested for 144h according to the experimental condition step of 7 in the GB/T24134-2009 standard, and the surface change is observed. The low-temperature resistance passes the low-temperature impact performance test, the sample plates are respectively placed into refrigerators at-25 ℃ and-35 ℃ for full cooling for 4h, then are taken out and placed in a room-temperature environment, the impact test is completed within 1min, and the impact resistance of the coating is observed;
TABLE 1 results of basic Performance test of examples and comparative examples
Table 2 results of other functional tests of examples and comparative examples
As can be seen from the test results of examples 1-4 and comparative example 1 in tables 1 and 2, the product of the invention has the advantages that through the synergy of all the components, especially the introduction of special micromolecule polysulfone chain segments, the obtained polyester resin and TGIC cured coating film has better appearance, gloss and boiling water boiling resistance, but has excellent common impact resistance, especially low temperature resistance and impact resistance, the impact resistance of the coating film can still smoothly pass through after 40 ℃/4h, the coating film has almost no change in high temperature conditions such as 180 ℃/128h for a long time, the lasting high temperature resistance is excellent, the abrasion resistance can reach about 4.21L/mum, the performance is better, and the comprehensive performance is excellent.
The coating film obtained by curing the common polyester resin and the TGIC adopted in the comparative example 1 has good appearance, luster and boiling resistance, but has obvious cracking phenomenon in low-temperature impact, obvious yellowing phenomenon in long-time high-temperature resistance test and cracks on the surface, which indicates that the common polyester resin has insufficient high-temperature and low-temperature resistance, the coating film has no outstanding wear resistance and is easy to wear on the surface in the using process.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (10)
1. The polyester resin is obtained by using bisphenol A, 4' -dichlorodiphenyl sulfone, N-Dimethylformamide (DMF), adipic acid, isophthalic acid, neopentyl glycol, thionyl chloride and 1, 4-cyclohexanedicarboxylic acid as main raw materials for reaction.
2. The polyester resin according to claim 1, wherein the polyester resin comprises the following main raw materials:
the auxiliary materials comprise sodium hydroxide aqueous solution, a catalyst, an antioxidant and hydrochloric acid.
3. The polyester resin according to claim 2, wherein the molar amount of bisphenol A is 1.1 to 1.2 times that of 4, 4' -dichlorodiphenyl sulfone.
4. The polyester resin according to claim 2, wherein the raw material is a 30-40% by mass aqueous solution of sodium hydroxide; the molar ratio of the sodium hydroxide to the bisphenol A is 2.05-2.1: 1.
5. The polyester resin according to claim 2, wherein the catalyst is monobutyltin oxide and is used in an amount of 0.08 to 0.2% based on the total molar amount of the raw materials.
6. The polyester resin according to claim 2, wherein the amount of the antioxidant is 0.2 to 0.5% based on the total molar amount of the raw materials.
7. A process for preparing the polyester resin of claims 1-6, comprising the steps of:
A. adding the adipic acid with the formula amount into a reactor 1, then dropwise adding thionyl chloride for stirring, carrying out reflux reaction after dropwise adding is finished, decompressing and removing excessive thionyl chloride after a system forms a transparent homogeneous phase to obtain adipoyl chloride, and storing for later use;
B. adding a sodium hydroxide aqueous solution with a formula amount into a reactor 2, stirring, and adding bisphenol A in batches for full reaction; after the bisphenol A is completely added, carrying out heat preservation reaction at the temperature of 50-60 ℃;
C. sampling and detecting the amount of free bisphenol A by using a liquid phase, stopping reaction when the amount of the free bisphenol A is less than 0.5 percent, starting vacuum, heating to 80-85 ℃, and removing water in a reaction system under reduced pressure;
D. when the water content in the system is lower than 1 percent, adding DMF and 4, 4' -dichlorodiphenyl sulfone according to the formula ratio, uniformly mixing, heating to 140-145 ℃, and carrying out heat preservation reaction;
E. detecting by liquid chromatography, stopping reaction when the content of free 4, 4' -dichlorodiphenyl sulfone is lower than 1%, cooling to room temperature, adding hydrochloric acid solution to adjust the pH value to 6-6.5, and fully stirring to convert the end group into phenolic hydroxyl; then carrying out suction filtration at room temperature, and removing generated sodium chloride to obtain DMF filtrate containing micromolecule polysulfone;
F. adding the filtrate into a polyester synthesis reactor 3, heating to 130-;
G. sampling and testing a hydroxyl value, adding isophthalic acid and neopentyl glycol according to the formula amount when the hydroxyl value is lower than 2mgKOH/g, gradually heating to 210-220 ℃ for carrying out heat preservation polymerization reaction, and removing a DMF solvent in the heating process;
H. when the acid value is reduced to 10mgKOH/g, adding 1, 4-cyclohexanedicarboxylic acid with the formula amount for end capping reaction, gradually heating to 230 +/-5 ℃, and preserving heat for reaction;
I. and when the acid value of the polymer reaches 30-37mgKOH/g, adding the antioxidant in a formula amount, uniformly mixing, cooling, discharging, cooling, crushing and granulating to obtain the polyester resin.
8. The method for preparing polyester resin according to claim 7, wherein the step G is preferably a temperature rising rate of 15-18 ℃/h; the temperature rise rate of 5-7 ℃/H is preferred in the step H.
9. The method for preparing polyester resin according to claim 7, wherein the degree of vacuum in step C is preferably controlled to be between-0.097 MPa and-0.099 MPa; the dehydration treatment in step F is preferably carried out with the water content in the reaction system being less than 0.5%.
10. Use of the polyester resin of any of claims 1 to 6 or the process for the preparation of the polyester resin of claims 7 to 9 for TGIC cured polyester powder coatings.
Priority Applications (1)
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