WO2020108263A1

WO2020108263A1 - Silicon-containing polyester resin used for high temperature-resistant powder coating

Info

Publication number: WO2020108263A1
Application number: PCT/CN2019/116152
Authority: WO
Inventors: 周韦明; 翟春海; 焦金牛
Original assignee: 安徽神剑新材料股份有限公司
Priority date: 2018-11-30
Filing date: 2019-11-07
Publication date: 2020-06-04
Also published as: CN109988491A

Abstract

A silicon-containing polyester resin used for a high temperature-resistant powder coating, comprising the following raw materials in weight percent: polyol: 34-44%wt; aromatic polyacid 43-58%wt; a branching agent: 0.0-2%wt; a raw material containing silicon: 3-12%; an acidolyzing agent: 0-5%wt; an esterification catalyst 0.03-0.15%wt; an alcoholyzing agent 0-3%; an antioxidant 0.01-2%wt; and a curing accelerator 0-1%wt. Further disclosed is a method for preparing the silicon-containing polyester resin. The resin has a number average molecular weight between 2500-5000 g/mol and a glass transition temperature (Tg) ≥54°C. After curing, a powder coating prepared by the resin has high gloss and excellent mechanical properties, and the light retention rate may reach greater than 50% at 280°C/2h, and the adhesion is higher than level 1.

Description

Silicone-containing polyester resin for high temperature resistant powder coating

Technical field

The invention relates to the technical field of coatings, in particular to a silicon-containing polyester resin for high temperature resistant powder coatings.

Background technique

As a green and environmentally friendly powder coating, powder coating is currently widely used in metal surface coating. At present, powder coatings are mainly based on epoxy resin, polyester resin, polyurethane and acrylic. The main chain is generally carbon-carbon or carbon-oxygen structure, which is limited by its molecular structure and its heat resistance is very poor, such as 280 ℃ Bake for 1h.

Compared with ordinary organic resins, silicone resins have excellent heat resistance due to the presence of silicon-oxygen bonds. For example, they can be used at 400°C for 3 hours and the gloss retention rate is greater than 50%. Therefore, the current powder coating industry often uses polyester resin and silicone resin as a co-agent to improve heat resistance. However, due to the poor compatibility of silicone resin and polyester resin, there is overflow phenomenon under the condition of direct co-agent, which has a great impact on the surface hardness, gloss, and adhesion of mechanical properties, which eventually leads to the coating film. Performance cannot be accepted by customers.

CN200810053803.8 discloses a silicone-modified polyester electronic packaging material, which mainly realizes that there is a silicon-oxygen bond in the resin main chain by means of alcoholysis of silicone resin and alcohol. There are a large number of tri- and tetra-substituted silicon atoms in the resin, which are also easy to self-polymerize after alcoholysis, so the production is not easy to control.

CN201110058635.3 discloses a heat-resistant hydroxy resin, the synthesis principle of which is also to use a silicone resin and a polyhydric alcohol to realize the main chain of the resin through alcoholysis. CN102838740A, CN103073711A, CN104987501A, CN104987501B, CN103131142A, CN102757727B, CN103980474A, CN105733417A disclose the preparation methods of silicone-containing polyester resins, which also use organosilicon intermediates and polyols to synthesize silicon-containing resins by alcoholysis to Realize the high temperature resistance of the substrate. Therefore, it also has the possibility of self-polymerization in the synthesis process and leads to production difficulties. CN105418905A and CN104829819A disclose the production process of silicon-containing polyester resin, which synthesizes silicon-containing mechanical resin by putting polyol, polyacid and organosilicon intermediate into the reaction kettle, which also has uncontrollability during the synthesis process. CN106220838A and CN106883399A also disclose the preparation method of silicone-modified polyester resin, which is mainly carried out in liquid or solvent, so the phenomenon of glue painting does not occur, and it is not suitable for the field of polyester resin for powder coating. CN108165169AE and CN108165144A disclose the synthesis of a silicone resin, which is mainly prepared by hydrolysis of a mixed solution of phenyltrichlorosilane equal to water and toluene, the presence of water and solvent leads to the production process requires the removal of the solvent The process is complicated. The monomers easily formed after hydrolysis of trichlorosilane and other monomers have three functionalities and are easy to self-polymerize, which makes the control difficult. Therefore, there is an urgent need for a preparation method of silicon-containing polyester resin for high-temperature resistant powder coatings that does not undergo self-polymerization in the production process, and the production process is simple and easy to control.

Summary of the invention

In order to solve the above problems, the present invention provides a silicon-containing polyester resin for high temperature resistant powder coatings, including polyols, aromatic polybasic acids, branching agents, silicon-containing raw materials, acidolysis agents, esterification catalysts, alcoholysis agents, and Oxygen agent is good and curing accelerator, and there is also a method for preparing the resin. The resin has a molecular weight of 2500-5000g/mol and a glass transition temperature (Tg) ≥ 54°C. The prepared powder coating is coated after curing With high gloss and excellent mechanical properties, the gloss retention rate at 280/2h can reach more than 50% and the adhesion is at least level 1, which solves the problems in the background technology. The object of the present invention is to provide a silicon-containing polyester resin for high-temperature resistant powder coatings, which includes the following weight percent raw materials: polyol: 34-44% wt; aromatic polybasic acid 43-58% wt; branching agent: 0.0 -2%wt; silicon-containing raw materials: 3-12%; acidolysis agent: 0-5%wt; esterification catalyst 0.03-0.15%wt; alcoholysis agent 0-3%; antioxidant 0.01-2%wt; Curing accelerator 0-1%wt. Further improvement is that the polyols are neopentyl glycol (NPG), ethylene glycol (EG), diethylene glycol (DEG), methyl propylene glycol (MPDI), ethyl butyl propylene glycol (BEPD) and cyclohexane One or more compositions in alkane dimethanol (CHDM).

A further improvement is that the branching agent is one or a mixture of trimethylolpropane (TMP) and trimethylolethane (TME).

A further improvement is that the aromatic polybasic acid is one or a mixture of phthalic acid (PTA) and isophthalic acid (IPA).

A further improvement is that the antioxidant is phosphite (tri[2.4-di-tert-butylphenyl] phosphite, antioxidant 626) and hindered phenolic antioxidant (tetra[β-(3,5 -Di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, antioxidant 1010) is synthesized by compounding, based on the total mass of the resin, its usage is 0.01-2%wt.

A further improvement is that the alcoholysis agent is one or a combination of neopentyl glycol or trimethylolpropane.

A further improvement is that the antioxidant is tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethylammonium chloride, triphenylethylphosphonium bromide, dibutyltin dilaurate One or more types, based on the total mass of the resin, its usage is 0.01-1%wt.

Further improvement is that the esterification catalyst is a tin catalyst, which is one or more of dibutyltin oxide, tributyltin oxide, dihydroxybutyltin chloride, stannous oxalate, monobutyltin oxide Based on the total mass of the resin, its usage is 0.03-0.15%wt.

Further improvement is that the acidolysis agent is one or more of isophthalic acid (IPA), adipic acid (ADA), 1,4-cyclohexanedicarboxylic acid (CHDA) and fumaric acid (FCC) the mix of.

A further improvement is that the resin is a bifunctional polyester resin of carboxyl terminated polyester resin or hydroxyl terminated polyester resin or both.

A further improvement is that the silicon-containing raw material of the resin is disubstituted silicone oil or dichlorosilane or disubstituted alkylsilane.

A further improvement is that the silicon-containing raw material of the resin is disubstituted silicone oil, which is dimethyl silicone oil or diethyl silicone oil or diphenyl silicone oil.

A further improvement is that the silicon-containing raw material of the resin is dichlorosilane, which is dimethyldichlorosilane or diethyldichlorosilane or diphenylsilane.

Further improvement lies in that the silicon-containing raw material of the resin is di-substituted alkyl silane or dimethyl dimethoxy silane or dimethyl diethoxy silane or diethyl dimethoxy silane or diethyl diethyl Oxysilane or diphenyldimethoxysilane or diphenyldiethoxysilane.

A further improvement is that the resin is a carboxyl-terminated polyester resin with an acid value range of 25-55 mgKOH/g; the resin is a hydroxyl-terminated polyester resin with a hydroxyl value range of 25-120 mgKOH/g; the resin is a bifunctional polyester resin The acid value range is 15-55mgKOH/g, and the hydroxyl value range is 15-55mgKOH/g.

A further improvement is that the resin is a carboxyl-terminated polyester resin, and its synthesis method is: the formula amount of polyol, branching agent and silicon-containing raw materials are put into a reaction kettle to be heated and melted, and then slowly heated to 195°C in a nitrogen atmosphere to No liquid production, then lower the temperature to 140-185°C and put the aromatic acid and an appropriate amount of catalyst into the reactor at the same time, slowly increase the temperature to 235-255°C in a nitrogen atmosphere and maintain it. After the system is clarified, sample to detect the acid value (AV) When it reaches 5-20mgKOH/g, add secondary acid hydrolysis agents IPA, ADA, CHDA, FCC, etc. and maintain the temperature at 235-250 ℃ for acid hydrolysis and end-blocking; when the acid value of the polyester is 35-70 ℃, the temperature will be reduced to 230- Condensation at 240 ℃ and vacuum (-0.1MPA) for a period of time, so that the acid value of the polyester reaches 25-55; then the temperature is reduced to 180-230 ℃, antioxidants and curing accelerators are added and maintained for 5-30min, then discharged.

A further improvement is that the resin is a hydroxyl-terminated polyester resin, and its synthesis method is: the formula amount of polyol, branching agent and silicon-containing raw materials are put into a reaction kettle to be heated and melted, and then slowly heated to 195°C in a nitrogen atmosphere Until no liquid production, then reduce the temperature to 140-185 ℃ and put the aromatic acid and the appropriate amount of catalyst into the reactor at the same time, slowly increase the temperature to 235-255 ℃ in a nitrogen atmosphere and maintain it. After the system is clarified, sample and test the acid value (AV ) When it reaches 5-20mgKOH/g, the temperature is reduced to 230-240°C and polycondensation is carried out in vacuum (-0.1MPA) for a period of time, so that the acid value of the polyester is less than 2; then the temperature is reduced to 180-230°C and antioxidants and curing accelerators are added And maintain 5-30min after discharge.

A further improvement is that the resin is a carboxyl-terminated and hydroxy-bifunctional polyester resin, and its synthesis method is: the formula amount of polyol, branching agent and silicon-containing raw materials are put into the reaction kettle to be heated and melted, and then slowly in a nitrogen atmosphere Raise the temperature to 195°C to no liquid production, then cool to 140-185°C and put the aromatic acid and the appropriate amount of catalyst into the reactor at the same time, slowly raise the temperature to 235-255°C in a nitrogen atmosphere and maintain it. After the system is clarified, take a sample test When the acid value (AV) reaches 5-20mgKOH/g, add secondary acid hydrolysis agents IPA, ADA, CHDA, FCC, etc. and maintain the temperature at 235-250 ℃ for acid hydrolysis and end-blocking; the acid value of the polyester is 30-70mgKOH/ At g, the temperature is reduced to 230-240°C and the polycondensation is carried out under vacuum (-0.1MPA) for a period of time, so that the acid value of the polyester reaches 25-55; then the temperature is reduced to 210-230°C, the alcoholysis agent is added and maintained for 20min, and then the temperature is reduced to 180- Antioxidant and curing accelerator were put in at 225°C and maintained for 5-30 minutes before discharging.

Further improvement lies in that the resin data molecular weight is in the range of 2500-5000g/mol, and the glass transition temperature Tg≥54°C.

A further improvement is that the resin has a glass transition temperature Tg>60°C.

Further improvement lies in: the resin is added with curing agent (triglycidyl isocyanurate (TGIC), hydroxyalkylamide (HAA) and blocked isocyanate), curing accelerator, pigment, filler, leveling agent and degassing agent High temperature resistant powder coating.

A further improvement is that the high-temperature resistant powder coating prepared by the resin is cured to obtain a coating with good gloss and good mechanical properties. The coating can achieve a gloss retention rate of more than 50% at 280/2h and an adhesion level of 1 or more.

The beneficial effects of the present invention: the resin raw material of the present invention uses polyol, aromatic polybasic acid, branching agent, silicon-containing raw material, acidolysis agent, esterification catalyst, alcoholysis agent, antioxidant and curing accelerator, and also There is a method for preparing the resin. The molecular weight of the resin is 2500-5000g/mol, and the glass transition temperature (Tg) ≥ 54°C. The prepared powder coating has high gloss and excellent mechanical properties after curing. The light retention rate of /2h can reach more than 50% and the adhesion is above grade 1.

detailed description

In order to deepen the understanding of the present invention, the present invention will be further described in detail in conjunction with the following examples, which are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention.

Example one:

The resin is a carboxyl-terminated polyester resin, and its synthesis method is: put the formula amount of polyol, branching agent and silicon-containing raw materials into a reaction kettle to heat and melt, and then slowly raise the temperature to 195°C in a nitrogen atmosphere to no liquid production. Subsequently, the temperature was lowered to 140°C and the aromatic acid and the appropriate amount of catalyst were simultaneously put into the reactor. The temperature was slowly raised to 235°C in a nitrogen atmosphere and maintained. After the system was clarified, the sample was taken and the acid value (AV) reached 5mgKOH/g. Acid hydrolysis agent IPA, ADA, CHDA, FCC, etc. and maintain the temperature at 235 ℃ for acid hydrolysis end capping; when the acid value of the polyester is 35-70 ℃, the temperature is reduced to 230 ℃ and vacuum (-0.1MPA) polycondensation for a period of time, so that The acid value of the polyester reaches 25; after that, the temperature is reduced to 180°C, and the antioxidant and curing accelerator are added and maintained for 5 minutes, and then discharged.

Example 2:

The resin is a hydroxyl-terminated polyester resin, and its synthesis method is as follows: the formulated amount of polyol, branching agent and silicon-containing raw materials are put into a reaction kettle to be heated and melted, and then slowly heated to 195°C in a nitrogen atmosphere to no liquid production Then, the temperature was lowered to 140°C and the aromatic acid and an appropriate amount of catalyst were simultaneously put into the reaction kettle. The temperature was slowly raised to 235°C and maintained in a nitrogen atmosphere. After the system was clarified, the temperature was reduced to 5mgKOH/g by sampling and detection. Polycondensation at 230°C and vacuum (-0.1MPA) for a period of time, so that the acid value of the polyester is 1; then the temperature is reduced to 180°C, antioxidants and curing accelerators are added and maintained for 5 minutes, and then discharged.

Example three:

The resin is a carboxyl-terminated polyester resin, and its synthesis method is: put the formula amount of polyol, branching agent and silicon-containing raw materials into a reaction kettle to heat and melt, and then slowly raise the temperature to 195°C in a nitrogen atmosphere to no liquid production. Subsequently, the temperature was lowered to 165°C and the aromatic acid and an appropriate amount of catalyst were simultaneously put into the reactor. The temperature was slowly raised to 245°C and maintained in a nitrogen atmosphere. After the system was clarified, the sample was taken and the acid value (AV) reached 12mgKOH/g. Acid hydrolysis agent IPA, ADA, CHDA, FCC, etc. and maintain the temperature at 242 ℃ for acid hydrolysis end capping; when the acid value of the polyester is 35-70 ℃, the temperature is reduced to 235 ℃ and vacuum (-0.1MPA) polycondensation for a period of time, so that The acid value of the polyester reaches 40; after that, the temperature is lowered to 200°C, and the antioxidant and curing accelerator are added and maintained for 18 minutes before discharging.

Example 4:

The resin is a hydroxyl-terminated polyester resin, and its synthesis method is as follows: the formulated amount of polyol, branching agent and silicon-containing raw materials are put into a reaction kettle to be heated and melted, and then slowly heated to 195°C in a nitrogen atmosphere to no liquid production Then, the temperature was lowered to 185°C and the aromatic acid and the appropriate amount of catalyst were simultaneously put into the reactor. The temperature was slowly raised to 255°C in a nitrogen atmosphere and maintained. After the system was clarified, a sample was taken and the acid value (AV) reached 20mgKOH/g. Condensation at 240℃ and vacuum (-0.1MPA) for a period of time, so that the acid value of the polyester is 1; then the temperature is lowered to 230℃ and the antioxidant and curing accelerator are added and maintained for 30min.

Example 5:

The resin is a carboxyl-terminated polyester resin, and its synthesis method is: put the formula amount of polyol, branching agent and silicon-containing raw materials into a reaction kettle to heat and melt, and then slowly raise the temperature to 195°C in a nitrogen atmosphere to no liquid production. Subsequently, the temperature was lowered to 185°C and the aromatic acid and an appropriate amount of catalyst were simultaneously put into the reactor. The temperature was slowly raised to 255°C in a nitrogen atmosphere and maintained. After the system was clarified, the sample was taken and the acid value (AV) reached 20mgKOH/g. Acid hydrolysis agent IPA, ADA, CHDA, FCC, etc. and maintain the temperature at 250 ℃ for acid hydrolysis and end-blocking; when the acid value of the polyester is 70 ℃, the temperature is reduced to 240 ℃ and vacuum (-0.1MPA) polycondensation for a period of time, making polyester The acid value reached 55; then the temperature was lowered to 230°C and the antioxidant and curing accelerator were added and maintained for 30 minutes before discharging.

Embodiment 6: The resin is a carboxyl-terminated and hydroxy-bifunctional polyester resin, and its synthesis method is: the formula amount of polyol, branching agent and silicon-containing raw materials are put into a reaction kettle to be heated and melted, and then slowly in a nitrogen atmosphere Raise the temperature to 195℃ to no liquid production, then lower the temperature to 160℃ and put the aromatic acid and the appropriate amount of catalyst into the reactor at the same time, slowly raise the temperature to 245℃ in the nitrogen atmosphere and maintain it. After the system is clarified, sample to detect the acid value (AV ) When it reaches 15mgKOH/g, add secondary acid hydrolysis agents IPA, ADA, CHDA, FCC, etc. and maintain the temperature at 242 ℃ for acid hydrolysis and end-blocking; when the acid value of the polyester is 50, lower the temperature to 235 ℃ and vacuum (-0.1MPA ) Polycondensation for a period of time, so that the acid value of the polyester reaches 35; then the temperature is reduced to 220 ℃ and the alcoholysis agent is added and maintained for 20 minutes, then the temperature is reduced to 200 ℃ and the antioxidant and curing accelerator are injected and maintained for 20 minutes.

Table 1 shows the polyester resin components, the control acid value and performance in the production process of each of Examples 1 to 6 (each unit is g)

Continued from the table above

Example 7: The performance of the saturated polyester resin synthesized in the above example can be reflected by the performance of the powder coating.

The saturated polyester resins synthesized in the above Examples 1-6 are respectively divided into curing agent (triglycidyl isocyanurate (TGIC), blocked isocyanate (B1530)), leveling agent, titanium dioxide, barium sulfate, benzoin Weigh with 701B etc. according to the ratio in Table 2 and mix well. Melt it with a screw extruder and extrude, tablet, crush and sieve to make a powder coating. Then the powder coating is sprayed on the surface of the metal plate after the surface phosphating treatment, and the various properties of the system are tested after curing under appropriate curing conditions, and then the cured coating is placed at 280 ℃/2h for over-baking, testing The heat resistance and adhesion are as follows.

Table 2. Composition and performance of powder coatings

It can be seen from Table 2 that the polyester resins of Examples 1-6 have excellent heat resistance after being prepared as a powder coating, and the gloss retention of the coating after over-baking at 280°C/2h> 50%, and the adhesion is level 1, showing excellent heat resistance.

The present invention can be described in other specific forms that do not violate the spirit or main features of the present invention. The above embodiments of the present invention can only be considered as descriptions of the invention rather than limitations, such as not being limited to the one-step preparation method of the carboxyl-terminated saturated polyester resin described in the present invention. A one-step preparation scheme is adopted, in which polyols, aromatic polybasic acids, fatty polybasic acids, branching agents, acidolysis agents, and esterification catalysts are uniformly mixed to prepare a saturated resin by esterification condensation reaction, and the invention can also be obtained. The polyester resin mentioned. Therefore, any slight modification and equivalent change modification made to the above embodiments according to the essential technology of the present invention belong to the scope of the technical solution of the present invention.

Claims

A silicon-containing polyester resin for high-temperature powder coatings, characterized in that it includes the following weight percent raw materials: polyol: 34-44%wt; aromatic polyacid 43-58%wt; branching agent: 0.0-2 %Wt; silicon-containing raw materials: 3-12%; acidolysis agent: 0-5%wt; esterification catalyst 0.03-0.15%wt; alcoholysis agent 0-3%; antioxidant 0.01-2%wt; curing promotion Agent 0-1%wt.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, wherein the polyol is neopentyl glycol (NPG), ethylene glycol (EG), diethylene glycol (DEG) ), one or more of methyl propylene glycol (MPDI), ethyl butyl propylene glycol (BEPD) and cyclohexane dimethanol (CHDM).
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, wherein the branching agent is trimethylolpropane (TMP) and trimethylolethane (TME). One or a mixture of the two.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, wherein the aromatic polybasic acid is one or both of phthalic acid (PTA) and isophthalic acid (IPA) Mixture.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, wherein the antioxidant is phosphite (tri [2.4-di-tert-butylphenyl] phosphite, resistant Oxygen agent 626) and hindered phenolic antioxidants (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, antioxidant 1010) were synthesized in a way based on The total mass of the resin is 0.01-2%wt.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, wherein the alcoholysis agent is one or a combination of neopentyl glycol or trimethylolpropane.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, wherein the antioxidant is tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethyl chloride Ammonium chloride, triphenylethylphosphonium bromide, one or more of dibutyltin dilaurate, based on the total mass of the resin, its usage is 0.01-1%wt.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, characterized in that the esterification catalyst is a tin catalyst, which is dibutyltin oxide, tributyltin oxide, dihydroxybutyrate One or more of tin tin chloride, stannous oxalate, and monobutyl tin oxide, based on the total mass of the resin, its usage is 0.03-0.15%wt.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, characterized in that the acidolysis agent is isophthalic acid (IPA), adipic acid (ADA), 1,4 cyclohexane A mixture of one or more of alkanedicarboxylic acid (CHDA) and fumaric acid (FCC).
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, characterized in that the resin is a bifunctional polyester resin of carboxyl-terminated polyester resin or hydroxyl-terminated polyester resin or both.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1 or 10, characterized in that the silicon-containing raw material of the resin is di-substituted silicone oil or dichlorosilane or di-substituted alkylsilane.
The silicon-containing polyester resin for high temperature powder coatings according to claim 11, characterized in that the silicon-containing raw material of the resin is di-substituted silicone oil, which is dimethyl silicone oil or diethyl silicone oil or diphenyl silicone oil .
The silicon-containing polyester resin for high temperature powder coatings according to claim 11, characterized in that the silicon-containing raw material of the resin is dichlorosilane, which is dimethyldichlorosilane or diethyldichlorosilane or dichlorosilane Phenylsilane.
The silicon-containing polyester resin for high-temperature powder coatings according to claim 11, characterized in that the silicon-containing raw material of the resin is di-substituted alkylsilane or dimethyldimethoxysilane or dimethyl Diethoxysilane or diethyldimethoxysilane or diethyldiethoxysilane or diphenyldimethoxysilane or diphenyldiethoxysilane.
The silicon-containing polyester resin for high temperature powder coatings according to claim 10, characterized in that: the resin is a carboxyl-terminated polyester resin with an acid value ranging from 25 to 55 mgKOH/g; the resin is a hydroxyl-terminated polyester The resin has a hydroxyl value range of 25-120 mgKOH/g; the resin is a bifunctional polyester resin with an acid value range of 15-55 mgKOH/g and a hydroxyl value range of 15-55 mgKOH/g.
The silicon-containing polyester resin for high temperature powder coatings according to claim 10 or 15, characterized in that: the resin is a carboxyl-terminated polyester resin, and its synthesis method is: the formula amount of polyol and branching agent Put the silicon-containing raw materials into the reactor for heating and melting, and then slowly raise the temperature to 195°C in a nitrogen atmosphere to no liquid production, and then cool to 140-185°C and put the aromatic acid and an appropriate amount of catalyst into the reactor at the same time. Slowly increase the temperature to 235-255 ℃ and maintain it. After the system is clarified, sample and test the acid value (AV) to reach 5-20mgKOH/g. Add secondary acidolysis agents IPA, ADA, CHDA and FCC, etc. and maintain the temperature at 235-250 ℃ Carry out acid hydrolysis and end-capping; when the acid value of the polyester is 35-70 ℃, cool down to 230-240 ℃ and vacuum (-0.1MPA) polycondensation for a period of time, so that the polyester acid value reaches 25-55; then cool to Antioxidant and curing accelerator are injected at 180-230°C and maintained for 5-30 minutes before discharging.
The silicon-containing polyester resin for high-temperature powder coatings according to claim 10 or 15, characterized in that the resin is a hydroxyl-terminated polyester resin, and its synthesis method is: combining the formulated amount of polyol and branching agent Put it into a reactor with silicon-containing raw materials for heating and melting, and then slowly raise the temperature to 195°C in a nitrogen atmosphere to no liquid production, and then lower the temperature to 140-185°C and put the aromatic acid and an appropriate amount of catalyst into the reactor at the same time. Slowly increase the temperature to 235-255°C in the atmosphere and maintain it. After the system is clarified, take a sample and measure the acid value (AV) to reach 5-20mgKOH/g. Reduce the temperature to 230-240°C and condense in vacuum (-0.1MPA) for a period of time The acid value of <2; then drop the temperature to 180-230 ℃, put antioxidant and curing accelerator and maintain it for 5-30min, then discharge.
The silicon-containing polyester resin for high temperature powder coatings according to claim 10 or 15, characterized in that the resin is a carboxyl-terminated and hydroxy-functional polyester resin, and its synthesis method is: the formula amount of polyol , Branching agent and silicon-containing raw materials are put into the reaction kettle for heating and melting, and then slowly heated to 195°C in a nitrogen atmosphere to no liquid production, and then cooled to 140-185°C and the aromatic acid and an appropriate amount of catalyst are simultaneously put into the reaction kettle In the nitrogen atmosphere, slowly raise the temperature to 235-255°C and maintain it. After the system is clarified, take a sample and test the acid value (AV) to reach 5-20mgKOH/g. Add the secondary acidolysis agents IPA, ADA, CHDA, FCC, etc. and maintain Carry out acid hydrolysis and capping at a temperature of 235-250℃; when the acid value of the polyester is 30-70mgKOH/g, the temperature is reduced to 230-240℃ and vacuum (-0.1MPA) polycondensation for a period of time, so that the acid value of the polyester reaches 25- 55; The temperature is then reduced to 210-230°C and the alcoholysis agent is added and maintained for 20min. The temperature is then reduced to 180-225°C and the antioxidant and curing accelerator are injected and maintained for 5-30min.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, characterized in that the resin data molecular weight is 2500-5000g/mol, and the glass transition temperature Tg ≥ 54°C.
The silicon-containing polyester resin for high temperature powder coatings according to claim 19, wherein the resin has a glass transition temperature Tg>60°C.
The silicon-containing polyester resin for high temperature powder coatings according to claim 1, characterized in that: the resin is added with a curing agent (triglycidyl isocyanurate (TGIC), hydroxyalkylamide (HAA) and blocking Type isocyanate), curing accelerator, pigment, filler, leveling agent and degassing agent are prepared into high temperature resistant powder coatings.
The silicon-containing polyester resin for high temperature resistant powder coatings according to claim 21, characterized in that: after curing the high temperature resistant powder coating prepared by the resin, a coating with good gloss and good mechanical properties is obtained, and the coating In 280/2h, the gloss retention rate can reach more than 50% and the adhesion is more than level 1.