CN116284684B - High-gloss high-temperature-resistant epoxy resin for powder coating and preparation method thereof - Google Patents
High-gloss high-temperature-resistant epoxy resin for powder coating and preparation method thereofInfo
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- CN116284684B CN116284684B CN202310059193.7A CN202310059193A CN116284684B CN 116284684 B CN116284684 B CN 116284684B CN 202310059193 A CN202310059193 A CN 202310059193A CN 116284684 B CN116284684 B CN 116284684B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/02—Polycondensates containing more than one epoxy group per molecule
- C08G59/04—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/02—Polycondensates containing more than one epoxy group per molecule
- C08G59/022—Polycondensates containing more than one epoxy group per molecule characterised by the preparation process or apparatus used
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/42—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
- C08G59/4215—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof cycloaliphatic
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- C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
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- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/03—Powdery paints
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/18—Fireproof paints including high temperature resistant paints
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Abstract
The invention relates to an epoxy resin for a high-gloss and high-temperature-resistant powder coating, which is prepared by using 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid, epichlorohydrin, sodium hydroxide, hydrogenated bisphenol A, a catalyst and the like as main raw materials through reaction, wherein the finally prepared epoxy resin chain segments mainly comprise cyanuric acid rings and hydrogenated bisphenol A chain segments with excellent high-temperature resistance, the obtained epoxy resin has excellent high-temperature resistance, and the cyclohexanecarboxylic acid ester specially introduced into the chain segment structure has excellent high-temperature resistance on one hand, and more importantly, has the functions of assisting the lubrication and leveling of the epoxy resin chain segments and improving gloss in the curing film forming process, and the obtained coating film has excellent high-temperature resistance, leveling and gloss after being cured at low temperature by an anhydride curing agent.
Description
Technical Field
The invention belongs to the technical field of chemical products, and particularly relates to an epoxy resin for high-gloss and high-temperature-resistant powder coating and a preparation method thereof.
Background
With the increase of paint powder conversion speed, powder coatings have become one of the most common metal surface coating coatings due to their unique environmental protection characteristics. Epoxy powder coatings are widely used because of their excellent adhesion and other properties. In the related special fields, such as the coating aspect of high-temperature metal surfaces of a gas furnace, a heater and the like, the traditional E-12 epoxy resin is insufficient in high-temperature resistance due to the self common bisphenol A structure, the coating film is easy to yellow and crack and even fall off, the requirement of high-temperature resistance (250/48 h) is difficult to meet, and although part of research adopts special raw materials and processes to prepare a high-temperature-resistant coating film product, the cost is too high on one hand, and on the other hand, the gloss of the coating film is insufficient due to the excessively hard chain segments of the epoxy resin, so that the high-gloss coating film of more than 95% is difficult to achieve. How to obtain a special epoxy resin product with high temperature resistance and excellent coating film gloss is a difficult problem to be solved in industry.
Aiming at the problems of high temperature resistant epoxy powder coating, the invention mainly uses 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid, epichlorohydrin, sodium hydroxide, hydrogenated bisphenol A, catalyst and the like as main raw materials to react, the prepared epoxy resin chain segments are mainly cyanuric acid and hydrogenated bisphenol A chain segments with excellent high temperature resistance, the finally obtained epoxy resin has excellent high temperature resistance, and the cyclohexanecarboxylate specially introduced in the chain segment structure has excellent high temperature resistance on one hand, and more importantly, has the functions of assisting the lubrication, leveling and gloss improvement of the epoxy resin chain segments in the curing film forming process, and the obtained coating film has excellent high temperature resistance, leveling and gloss after the epoxy resin and the anhydride curing agent are cured, and the whole preparation does not need expensive raw materials and special processes, thereby having lower cost and better market prospect.
Disclosure of Invention
The invention relates to an epoxy resin for high-gloss and high-temperature-resistant powder coating, which is prepared by using raw materials including 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid, epichlorohydrin, sodium hydroxide, hydrogenated bisphenol A and a catalyst through reaction.
An epoxy resin for high-gloss and high-temperature-resistant powder coating, which comprises the following raw materials in parts by mole:
In addition, the composition also comprises a catalyst 1, a catalyst 2 and a catalyst 3.
Further, the catalyst 1 is p-toluenesulfonic acid, the dosage is 0.4-0.8% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, the catalyst 2 is boron trifluoride diethyl ether, the dosage is 0.8-1.2% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, and the catalyst 3 is ethyl triphenylphosphine bromide, the dosage is 0.1-0.15% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid.
A preparation method of high-gloss and high-temperature-resistant epoxy resin for powder coating comprises the following steps:
A. adding 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid and a catalyst 1 in a formula amount into a reaction kettle, starting stirring, and heating to 135-140 ℃ for reflux water diversion esterification reaction;
B. Sampling and detecting the acid value of the reaction mixture, and when the acid value of the system mixture reaches below 1mgKOH/g, indicating that the cyclohexanecarboxylic acid is basically esterified, starting a vacuum system at the moment, and continuously carrying out reduced pressure reaction at 135-140 ℃ to remove the xylene solvent in the system;
C. When the xylene content of the system mixture is lower than 2%, removing the vacuum system to obtain an esterified intermediate 1, cooling to 70-75 ℃, adding the epoxy chloropropane with the formula amount to enable the epoxy chloropropane to be fully dissolved into one phase, adding the catalyst 2 with the formula amount, and continuing to perform full ring-opening reaction at 70-75 ℃;
D. Sampling and carrying out liquid chromatography detection, when the content of the esterified intermediate 1 is lower than 1%, indicating that the esterification intermediate is basically subjected to ring-opening reaction with epoxy chloropropane, then cooling to 35-40 ℃, adding sodium hydroxide with the formula amount for ring-closing reaction, and continuing to carry out heat preservation reaction after the addition is finished;
E. Detecting the change of the pH value in the system, when the pH value does not change obviously within 30min, carrying out suction filtration on the material to remove byproduct solid sodium chloride to obtain an organic phase containing epichlorohydrin, washing with water to remove impurities, layering to remove water phase to obtain a washed organic phase, and then starting a vacuum system, and gradually heating to 75-80 ℃ under negative pressure to remove residual water and epichlorohydrin in the organic phase;
F. and when the volatile matter content is less than 1%, removing the vacuum system to obtain a cyclized intermediate 2, adding the hydrogenated bisphenol A with the formula amount, heating to 100-105 ℃, uniformly stirring, adding the catalyst 3 with the formula amount, uniformly stirring, gradually heating to 155-160 ℃, sampling and detecting the epoxy equivalent and the softening point, stopping the reaction when the epoxy equivalent reaches 920-980g/mol and the softening point reaches 80-86 ℃, discharging at high temperature, and performing aftertreatment to obtain the epoxy resin for the high-gloss high-temperature-resistant powder coating.
Further, in steps A and B, the reaction temperature is preferably 138 to 140 ℃.
Further, in the step B, the vacuum degree is controlled to be-0.095 to-0.097 Mpa.
In the step D, the sodium hydroxide with the formula amount is added for ring closure reaction for 5 to 7 times after the temperature is reduced, the interval is 8 to 12 minutes each time, and the heat preservation reaction is continued after the addition is finished.
In the step E, the pH value is not obviously changed within 30min, namely, the change value is less than or equal to 0.1, the water washing and impurity removal comprises the steps of washing for 2 times by using 1/2 mass of epichlorohydrin to remove impurities respectively, and layering to remove the water phase, so as to obtain a water-washed organic phase, and the negative pressure of a vacuum system is kept between-0.098 and-0.099 Mpa.
Further, in the step F, the temperature is gradually increased to 155-160 ℃ at a temperature increasing speed of 10-12 ℃ per hour, and the post-treatment comprises cooling the resin by a steel belt with condensed water, and then crushing and granulating.
The invention also relates to the application of the epoxy resin for the high-gloss and high-temperature-resistant powder coating or the epoxy resin for the high-gloss and high-temperature-resistant powder coating obtained by the preparation method in the powder coating, which is obtained by spraying the powder coating on a substrate by adopting an electrostatic spray gun and curing.
For example, the preparation method of the high-gloss and high-temperature-resistant epoxy resin for the powder coating comprises the following steps:
A. Adding 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid and a catalyst 1 in a formula amount into a reaction kettle, starting stirring, and heating to 138-140 ℃ for reflux water diversion esterification reaction;
B. Sampling and detecting the acid value of the reaction mixture, when the acid value of the system mixture reaches below 1mgKOH/g, indicating that the cyclohexanecarboxylic acid is basically esterified, starting a vacuum system at the moment, controlling the vacuum degree to be between-0.095 and-0.097 Mpa, and continuously carrying out reduced pressure at 138-140 ℃ to remove the xylene solvent in the system;
C. When the xylene content of the system mixture is lower than 2%, removing the vacuum system to obtain an esterified intermediate 1, cooling to 70-75 ℃, adding the epoxy chloropropane with the formula amount to enable the epoxy chloropropane to be fully dissolved into one phase, and adding the catalyst 2 with the formula amount to continuously perform full ring-opening reaction at 70-75 ℃;
D. Sampling and carrying out liquid chromatography detection, when the content of the esterified intermediate 1 is lower than 1%, indicating that the esterification intermediate is basically subjected to ring-opening reaction with epoxy chloropropane, then cooling to 35-40 ℃, adding sodium hydroxide with the formula amount for ring-closing reaction for 5-7 times, keeping the temperature for reaction after the addition is finished for 8-12min each time;
E. Detecting the change of the pH value in the system, when the pH value is not obviously changed within 30min (the change value is less than or equal to 0.1), indicating that the ring-closure reaction is finished, carrying out suction filtration on the materials to remove byproduct solid sodium chloride to obtain an organic phase containing epichlorohydrin, washing with 1/2 mass of epichlorohydrin for 2 times to remove impurities respectively, and removing the water phase by layering to obtain a washed organic phase, then starting a vacuum system, and gradually heating to 75-80 ℃ under negative pressure (keeping-0.098 to-0.099 Mpa) to remove residual water and epichlorohydrin in the organic phase;
F. and when the volatile matter content is less than 1%, removing the vacuum system to obtain a cyclized intermediate 2, adding the hydrogenated bisphenol A with the formula amount, heating to 100-105 ℃, uniformly stirring, adding the catalyst 3 with the formula amount, uniformly stirring, gradually heating to 155-160 ℃ at the heating rate of 10-12 ℃ per hour, sampling, detecting the epoxy equivalent and the softening point, stopping the reaction when the epoxy equivalent reaches 920-980g/mol and the softening point reaches 80-86 ℃, discharging at a high temperature, cooling the resin by using a steel belt with condensed water, crushing and granulating, and obtaining the epoxy resin for the high-gloss and high-temperature-resistant powder coating.
Wherein, structure of esterification intermediate 1:
cyclizing the structure of intermediate 2:
The obtained epoxy resin is colorless or pale yellow transparent particles, the epoxy equivalent is 920-980g/mol, and the softening point is 80-86 ℃.
The formula of the epoxy powder coating can be obtained from the prepared filling auxiliary agents such as epoxy resin, 1,2, 4-cyclohexane trimethyl anhydride, barium sulfate, titanium pigment and the like, and the powder coating is sprayed on a tinplate substrate subjected to surface treatment by adopting an electrostatic spray gun and is cured to obtain the coating.
The invention has the beneficial effects that:
The invention mainly uses 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid, epichlorohydrin, sodium hydroxide, hydrogenated bisphenol A, catalyst and the like as main raw materials to react, the prepared epoxy resin chain segments are mainly cyanuric acid and hydrogenated bisphenol A chain segments with excellent high temperature resistance, the finally prepared epoxy resin has excellent high temperature resistance, the cyclohexanecarboxylate specially introduced into the chain segment structure has excellent high temperature resistance on one hand, and more importantly, the epoxy resin chain segments have the functions of lubricating, leveling assisting and improving gloss in the curing film forming process, and finally, the obtained coating film has excellent high temperature resistance, leveling and gloss after the epoxy resin and the anhydride curing agent are cured, and the whole preparation does not need expensive raw materials and special processes, so the cost is lower, and the coating film has better market prospect.
Detailed Description
For the purposes of promoting an understanding of the invention, reference will now be made in detail to various exemplary embodiments of the invention, which should not be considered as limiting the invention in any way, but rather as describing in more detail certain aspects, features and embodiments of the invention.
The raw materials are all commercial common industrial grade raw materials.
Example 1
An epoxy resin for high-gloss and high-temperature-resistant powder coating, which comprises the following raw materials in parts by mole:
the catalyst 1 is p-toluenesulfonic acid, the dosage is 0.6% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, the catalyst 2 is boron trifluoride diethyl ether, the dosage is 1% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, and the catalyst 3 is ethyl triphenylphosphine bromide, the dosage is 0.12% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid.
The preparation method of the epoxy resin for the high-gloss and high-temperature-resistant powder coating comprises the following steps:
A. Adding 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid and a catalyst 1 in a formula amount into a reaction kettle, starting stirring, and heating to 140 ℃ for reflux water diversion esterification reaction;
B. Sampling and detecting the acid value of the reaction mixture, when the acid value of the system mixture reaches below 1mgKOH/g, indicating that the cyclohexanecarboxylic acid is basically esterified, starting a vacuum system at the moment, controlling the vacuum degree to be-0.097 Mpa, and continuously carrying out reduced pressure at 140 ℃ to remove the xylene solvent in the system;
C. When the xylene content of the system mixture is lower than 2%, removing the vacuum system to obtain an esterified intermediate 1, cooling to 75 ℃, adding the epoxy chloropropane with the formula amount to enable the esterified intermediate and the epoxy chloropropane to be fully dissolved into one phase, and adding the catalyst 2 with the formula amount to continuously perform full ring-opening reaction at 75 ℃;
D. Sampling and carrying out liquid chromatography detection, when the content of the esterified intermediate 1 is lower than 1%, indicating that the esterification intermediate is basically subjected to ring-opening reaction with epoxy chloropropane, then cooling to 40 ℃, adding sodium hydroxide with the formula amount for ring-closing reaction for 7 times, and keeping the temperature for reaction after the addition is finished for 10min each time;
E. Detecting the change of the pH value in the system, when the pH value is not obviously changed within 30min (the change value is less than or equal to 0.1), indicating that the ring-closure reaction is finished, carrying out suction filtration on the materials to obtain solid sodium chloride as a byproduct, obtaining an organic phase containing epichlorohydrin, washing with 1/2 mass of epichlorohydrin for 2 times to remove impurities respectively, and removing the water phase by layering to obtain a washed organic phase, then starting a vacuum system, and gradually heating to 80 ℃ under negative pressure (keeping-0.098 Mpa) to remove residual water and epichlorohydrin in the organic phase;
F. And when the volatile matter content is less than 1%, removing the vacuum system to obtain a cyclized intermediate 2, adding the hydrogenated bisphenol A with the formula amount, heating to 105 ℃, stirring uniformly, adding the catalyst 3 with the formula amount, stirring uniformly, gradually heating to 160 ℃ at the heating rate of 12 ℃ per hour, sampling and detecting the epoxy equivalent and the softening point, stopping the reaction when the epoxy equivalent and the softening point reach the expected values, discharging at a high temperature, cooling the resin by using a steel belt with condensed water, crushing and granulating, and obtaining the high-gloss high-temperature-resistant epoxy resin for the powder coating.
The epoxy resin obtained was pale yellow transparent particles in appearance, the epoxy equivalent was 930/mol, and the softening point was 81 ℃.
Example 2
An epoxy resin for high-gloss and high-temperature-resistant powder coating, which comprises the following raw materials in parts by mole:
catalyst 1 was p-toluenesulfonic acid in an amount of 0.8% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, catalyst 2 was boron trifluoride diethyl ether in an amount of 1.2% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, and catalyst 3 was ethyltriphenylphosphine bromide in an amount of 0.15% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid.
The preparation method is the same as in example 1.
The epoxy resin obtained was pale yellow transparent particles in appearance, the epoxy equivalent was 974g/mol, and the softening point was 85 ℃.
Example 3
An epoxy resin for high-gloss and high-temperature-resistant powder coating, which comprises the following raw materials in parts by mole:
catalyst 1 was p-toluenesulfonic acid in an amount of 0.4% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, catalyst 2 was boron trifluoride diethyl ether in an amount of 0.8% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, and catalyst 3 was ethyltriphenylphosphine bromide in an amount of 0.1% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid.
The preparation method is the same as in example 1.
The epoxy resin obtained was pale yellow transparent particles in appearance, the epoxy equivalent was 961g/mol, and the softening point was 84 ℃.
Example 4
An epoxy resin for high-gloss and high-temperature-resistant powder coating, which comprises the following raw materials in parts by mole:
catalyst 1 was p-toluenesulfonic acid in an amount of 0.8% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, catalyst 2 was boron trifluoride diethyl ether in an amount of 1.2% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, and catalyst 3 was ethyltriphenylphosphine bromide in an amount of 0.15% by mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid.
The preparation method is the same as in example 1.
The epoxy resin obtained was colorless or pale yellow transparent particles in appearance, had an epoxy equivalent of 947g/mol and a softening point of 83 ℃.
Comparative example 1
As comparative example 1, the epoxy resin of example 1 was replaced with a conventional commercially available E-12 epoxy resin.
Available from Huangshan five-ring technologies Inc., epoxy equivalent 842g/mol, softening point 93 ℃.
The amount of the curing agent 1,2, 4-cyclohexane trimethanhydride was increased from 40g to 43g.
Comparative example 2
Other than comparative example 1, the curing conditions were merely changed to 180℃per 15min.
Application example
The formulation of the epoxy powder coating is generally as follows in parts by weight:
The preparation of the powder coating comprises the steps of uniformly mixing all materials according to the formula of the powder coating, carrying out high-temperature melt extrusion (the temperature of a screw is controlled at 125-135 ℃) by a double-screw extruder, tabletting, crushing, and crushing and sieving the tablets to obtain the powder coating (160-180 meshes). The powder coating is sprayed on the tinplate base material after surface treatment by adopting an electrostatic spray gun, and is solidified at 155 ℃ per 20min, so that the coating layer is obtained, and the film thickness is 80-90 mu m.
Performance comparison:
Coating index detection is carried out according to GB/T21776-2008 'powder coating and coating detection standard guide', and leveling grade is carried out according to JB-T3998-1999 'coating leveling coating and scraping determination method'.
The coating properties obtained from the powder coatings of the above examples and comparative examples are shown in table 1 below.
TABLE 1 film coating Properties
As can be seen from the comparison of examples 1-4 and comparative examples 1-2 in Table 1, the product of the invention adopts a special cyanuric acid ring as the main chain segment of the epoxy resin, the lubricating capability of the chain segment of the product is realized by the ester group on the structure, the gloss and the leveling grade of the coating are improved, the high temperature resistant powder coating is obtained under the condition of realizing low temperature curing (155 ℃ per 20 min), the appearance of the coating is smooth and smooth, the gloss is very high and is basically over 95 percent, the leveling grade is over 7, and the coating has excellent high temperature resistance, particularly has almost no obvious change after 250 ℃ per 50h, and has excellent comprehensive performance.
The conventional E-12 epoxy resin and 1,2, 4-cyclohexane trimellitic anhydride cured coating film adopted in comparative examples 1-2 cannot be sufficiently cured at 155 ℃ per 20min, so that the coating film is poor, and the normal high-temperature curing condition (180 ℃ per 15 min) adopted in comparative example 2 can be sufficiently cured, but the apparent, gloss and leveling properties of the coating film are generally poor, the high-temperature resistance is obviously inferior to that of the product of the invention, the yellowing of the coating film is obvious after 250 ℃ per 50h, and very slight cracks begin to appear.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
Claims (7)
1. An epoxy resin for high-gloss and high-temperature-resistant powder coating is characterized in that the epoxy resin is prepared by using raw materials including 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid, epichlorohydrin, sodium hydroxide, hydrogenated bisphenol A and a catalyst through reaction;
The raw materials comprise the following components in parts by mole:
In addition, the catalyst comprises a catalyst 1, a catalyst 2 and a catalyst 3, wherein the catalyst 1 is p-toluenesulfonic acid, the dosage of the catalyst is 0.4-0.8% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, the catalyst 2 is boron trifluoride diethyl ether, the dosage of the catalyst is 0.8-1.2% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid, and the catalyst 3 is ethyl triphenylphosphine bromide, and the dosage of the catalyst is 0.1-0.15% of the mass of 1,3, 5-tris (2-hydroxyethyl) cyanuric acid;
The preparation method of the epoxy resin comprises the following steps:
A. adding 1,3, 5-tri (2-hydroxyethyl) cyanuric acid, dimethylbenzene, cyclohexanecarboxylic acid and a catalyst 1 in a formula amount into a reaction kettle, starting stirring, and heating to 135-140 ℃ for reflux water diversion esterification reaction;
B. Sampling and detecting the acid value of the reaction mixture, starting a vacuum system when the acid value of the system mixture is less than 1mgKOH/g, and continuously carrying out reduced pressure reaction at 135-140 ℃ to remove the xylene solvent in the system;
C. When the xylene content of the system mixture is lower than 2%, removing the vacuum system to obtain an esterified intermediate 1, cooling to 70-75 ℃, adding the epoxy chloropropane with the formula amount to enable the epoxy chloropropane and the epoxy chloropropane to be fully dissolved into one phase, adding the catalyst 2 with the formula amount, and continuing to perform ring-opening reaction at 70-75 ℃;
D. Sampling and carrying out liquid chromatography detection, cooling to 35-40 ℃ when the content of the esterified intermediate 1 is lower than 1%, adding sodium hydroxide with the formula amount for ring closure reaction, and continuing to carry out heat preservation reaction after the addition is finished;
E. Detecting the change of the pH value in the system, when the pH value does not change obviously within 30min, carrying out suction filtration on the material to remove byproducts to obtain an organic phase containing epoxy chloropropane, washing with water to remove impurities, and layering to remove water phase to obtain a washed organic phase;
F. and when the volatile matter content is less than 1%, removing the vacuum system to obtain a cyclized intermediate 2, adding the hydrogenated bisphenol A with the formula amount, heating to 100-105 ℃, uniformly stirring, adding the catalyst 3 with the formula amount, uniformly stirring, gradually heating to 155-160 ℃, sampling and detecting the epoxy equivalent and the softening point, stopping the reaction when the epoxy equivalent reaches 920-980g/mol and the softening point reaches 80-86 ℃, discharging at high temperature, and performing aftertreatment to obtain the epoxy resin for the high-gloss high-temperature-resistant powder coating.
2. An epoxy resin for high gloss and high temperature resistant powder coating as defined in claim 1, wherein in steps a and B, the reaction temperature is 138-140 ℃.
3. The epoxy resin for high gloss and high temperature resistant powder coating according to claim 1, wherein in step B, the vacuum degree is controlled to-0.095 to-0.097 Mpa.
4. The epoxy resin for high-gloss and high-temperature-resistant powder coating according to claim 1, wherein in the step D, the temperature is reduced, the formula amount of sodium hydroxide is added for 5-7 times for ring closure reaction, each time for 8-12min, and the heat preservation reaction is continued after the addition is completed.
5. The epoxy resin for high-gloss and high-temperature-resistant powder coating according to claim 1, wherein in the step E, the pH value is not changed obviously within 30min and is not more than 0.1, the water washing and impurity removal comprises the steps of washing for 2 times by using 1/2 mass of epichlorohydrin to remove impurities respectively, and removing the water phase in a layering manner to obtain a water-washed organic phase, and the negative pressure of a vacuum system is kept between-0.098 and-0.099 Mpa.
6. An epoxy resin for high gloss and high temperature resistant powder coating as defined in claim 1, further characterized in that in step F, the temperature is gradually raised to 155-160 ℃ at a temperature raising rate of 10-12 ℃ per hour, the post-treatment comprises cooling the resin with a steel belt with condensed water, and then crushing and granulating.
7. The use of the epoxy resin for high gloss and high temperature resistant powder coating according to any one of claims 1 to 6 in powder coating, wherein the powder coating is sprayed on a substrate by an electrostatic spray gun and cured to obtain the coating.
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| CN110818883A (en) * | 2019-11-18 | 2020-02-21 | 黄山学院 | Epoxy resin for high gloss self-curing powder coating and preparation method of double kettle |
| CN112048057A (en) * | 2020-09-11 | 2020-12-08 | 安徽鑫友高分子新材料科技有限公司 | Epoxy resin, application and high-leveling ultralow-temperature curing type pure powder coating |
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| CN112375210B (en) * | 2020-11-04 | 2022-11-25 | 黄山新佳精细材料有限公司 | Phenol curing agent for high-temperature-resistant and high-hardness epoxy resin powder coating and preparation method thereof |
| CN112390930A (en) * | 2020-11-04 | 2021-02-23 | 黄山新佳精细材料有限公司 | Epoxy resin with excellent wear resistance and high and low temperature resistance for powder coating and preparation method thereof |
| CN113501934B (en) * | 2021-07-28 | 2023-06-30 | 黄山市源润新材料科技有限公司 | Epoxy resin for self-leveling low-temperature curing powder coating and preparation method thereof |
| CN113831505B (en) * | 2021-11-02 | 2024-02-06 | 黄山新佳精细材料有限公司 | High-gloss self-curing epoxy resin and preparation method and application thereof |
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| CN110818883A (en) * | 2019-11-18 | 2020-02-21 | 黄山学院 | Epoxy resin for high gloss self-curing powder coating and preparation method of double kettle |
| CN112048057A (en) * | 2020-09-11 | 2020-12-08 | 安徽鑫友高分子新材料科技有限公司 | Epoxy resin, application and high-leveling ultralow-temperature curing type pure powder coating |
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