A TMA-free indoor matte polyester resin and preparation method thereof

Abstract

The invention belongs to the field of polyester resin preparation, and specifically relates to a TMA-free indoor matte polyester resin and a preparation method thereof. The invention adopts 1,3,5-cyclohexanetriac acid with a low toxicity of a ring structure to replace the old toxic and carcinogenic TMA, thereby reducing the toxicity of the prepared resin, and at the same time, the polyester resin, the polyurethane resin, the epoxy resin and the modified filler are uniformly mixed according to the formula amount to obtain the TMA-free indoor matte polyester resin. The TMA-free indoor matte polyester resin of the invention can effectively improve the wear resistance, mechanical properties, corrosion resistance and other properties of the prepared resin coating.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester resins, and in particular relates to a TMA-free indoor matte polyester resin and a preparation method thereof. Background Art

[0002] With the continuous improvement of production level and human material level, the product categories of powder coating market are becoming more and more abundant. With the expansion of coating market, the market demand for product diversity is increasing, including the appearance gloss of products. People's requirements for the gloss of coatings in different occasions are no longer the same, and they are no longer satisfied with single high-gloss and bright-color coatings. Usually, the gloss of coatings for outdoor machinery, car shells, etc. on the market is high, while indoor products (especially those living or working for a long time) want coatings with lower gloss.

[0003] In the thermosetting powder coating market, the existing indoor matte powder coating has certain requirements for the matte property of the coating. Considering the product cost, the polyester resin used for indoor matte powder coating is mainly polyester / epoxy system. As the main matrix material of the matte powder coating film-forming material, the polyester resin plays a decisive role in the matte property of the coating. Trimellitic anhydride (TMA) is a chemical substance commonly used in polyester resins for matte powder coatings. The trimellitic anhydride (TMA) molecule contains benzene rings, carboxylic acid and anhydride structures at the same time, which can increase the glass transition temperature (Tg), crosslinking density, viscosity and acid value of polyester resins. Therefore, it is used as an acidolysis agent for indoor polyester resins. However, the benzene ring anhydride structure in TMA is irritating, and direct contact can easily cause symptoms such as eye damage, mucous membrane irritation, and respiratory allergies, and has a certain risk of carcinogenesis.

[0004] Therefore, in order to meet people's demand for matte and environmental protection of indoor coatings, there is an urgent need for a TMA-free indoor matte polyester resin and a preparation method thereof. Summary of the invention

[0005] The object of the present invention is to provide a TMA-free indoor matte polyester resin and a preparation method thereof.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a TMA-free indoor matte polyester resin comprises the following steps:

[0008] (1) Preparation of carboxyl-terminated polyester resin: 25-30 parts of diol, 1-3 parts of triol and 1-4 parts of trimethylolpropane are added into a reaction kettle, heated and stirred; then 60-70 parts of terephthalic acid and an esterification catalyst are added, and the temperature is slowly raised to 240°C; the esterification reaction takes about 48 hours, and after the esterification water generated by the reaction is completely discharged, the temperature is lowered to 220°C in the kettle, and 1,3,5-cyclohexanetricarboxylic acid and an auxiliary agent are added, and the temperature is raised to 240°C in the kettle, and the temperature is kept until the acid value reaches 60-70 mgKOH / g, and then the reaction kettle is vacuumed for 1-2 hours to remove side reactions, residual monomers and impurities generated in the reaction, and after vacuuming to an acid value of 50-60 mgKOH / g, the discharged material is left to cool to obtain a carboxyl-terminated polyester resin;

[0009] (2) Preparation of polyurethane resin: by weight, 40-45 parts of polyester polyol, 26-29 parts of hexamethylene diisocyanate, 6-9 parts of triethylenediamine and 20-25 parts of hydroxyl-terminated methyl vinyl silicone oil are mixed, heated to 100-110° C., reacted for 3-4 hours, cooled to room temperature, added with 6-8 parts of N-methyldiethanolamine, heated to 80-85° C., reacted for 3-5 hours, cooled to 30-35° C., neutralized with glacial acetic acid to a pH of 6-6.2, added with 48-50 parts of acetone to dilute, and acetone removed by vacuum to obtain polyurethane resin;

[0010] (3) Preparation of modified filler: The preparation method of the modified filler comprises the following steps:

[0011] S1: mixing silicon dioxide, boron carbide and aluminum oxide to obtain a mixed filler;

[0012] S2: Mix a mixed filler, hexadecyltrimethylammonium bromide, water and sodium chloride in a weight ratio of 10: (4-5): (15-18): (0.1-0.2), adjust the pH value of the system to 8.2-8.5, and ball mill the mixture in a ball mill at a speed of 400-450 r / min for 3-4 h, wash, filter and vacuum dry to obtain a pre-modified filler;

[0013] S3: Mix the pre-modified filler in a weight ratio of 5: (25-30): (1.5-2), 60-65% by mass ethanol aqueous solution and polyvinyl alcohol, and ball mill them in a ball mill at a speed of 300-350 r / min for 5-6 hours, wash, filter and dry to obtain a modified filler;

[0014] (4) The carboxyl-terminated polyester resin, 18-23 parts of polyurethane resin, 32-37 parts of epoxy resin and 8-12 parts of modified filler are mixed uniformly according to the formula amount to obtain a TMA-free indoor matte polyester resin.

[0015] Furthermore, the polyester polyol comprises polyester polyol I, polyester polyol II and polyester polyol III in a weight ratio of 1: (1.4-1.6): (0.5-0.7); the number average molecular weight of polyester polyol I is 600, and the hydroxyl value is 185-205 mgKOH / g; the number average molecular weight of polyester polyol II is 2000, and the hydroxyl value is 53-59 mgKOH / g; the number average molecular weight of polyester polyol III is 4000, and the hydroxyl value is 26-30 mgKOH / g.

[0016] The invention uses hydroxyl-terminated methyl vinyl silicone oil to modify the polyurethane resin, thereby improving the adhesion of the TMA-free indoor matte polyester resin; the invention introduces hydroxyl-terminated methyl vinyl silicone oil to improve the compatibility between the polyurethane resin and the polyester resin, reduce interface defects, and improve adhesion.

[0017] Further, silicon dioxide, boron carbide and aluminum oxide are mixed in a weight ratio of 1: (1.4-1.6): (0.2-0.5) to obtain a mixed filler.

[0018] Furthermore, the average particle size of silicon dioxide is 10 nm and the average specific surface area is 380 m 2 / g; the average particle size of boron carbide is 50nm, and the specific surface area is 30-50m 2 / g; the average particle size of alumina is 30nm, and the specific surface area is 10-20m 2 / g.

[0019] The present invention can improve the impact resistance of TMA-free indoor matte polyester resin by modifying three specific fillers. The interface compatibility between the filler and the polyester resin can be improved by surface modification treatment; the modified filler can be better dispersed in the resin matrix, reduce agglomeration, and form a uniform dispersion system; the combination of the three modified fillers can produce a multi-component synergistic effect, and the respective advantages can complement each other to form more optimized material properties; through reasonable selection and proportioning, appropriate hard segments and soft segments can be introduced into the material to balance rigidity and flexibility, thereby improving impact resistance.

[0020] Furthermore, the epoxy resin is a compound of epoxy resin I, epoxy resin II and epoxy resin III in a mass ratio of (1.5-1.7):1:(0.2-0.4), the epoxy equivalent of epoxy resin I is 184-194 g / Eq; the epoxy equivalent of epoxy resin II is 167-175 g / Eq, and the epoxy equivalent of epoxy resin III is 400-455 g / Eq.

[0021] During daily use and maintenance of automobiles, solvents are often needed to clean stains, grease and marks on the surface. A coating with good acetone wiping resistance can ensure that it will not be eroded or damaged by solvents during the cleaning process. The present invention can improve the acetone wiping resistance of indoor matte polyester resins without TMA by adding compounded epoxy resins. Epoxy resins have multiple epoxy groups (-COC-), which can undergo cross-linking reactions with carboxyl groups (-COOH) in polyester resins and hydroxyl groups (-OH) or isocyanate groups (-NCO) in polyurethane resins to form a more compact network structure. By selecting three epoxy resins with different epoxy equivalents, regions with different cross-linking densities can be formed in the material, thereby optimizing the overall cross-linking structure. Resins with high epoxy equivalents can provide more cross-linking points, while resins with low epoxy equivalents can provide more flexible segments. Through multiple mechanisms such as enhancing cross-linking density, improving interface compatibility, improving chemical stability, optimizing microstructure and enhancing mechanical properties, the overall performance and acetone wiping resistance of the material are improved.

[0022] Further, the diol includes 12-16 parts of ethylene glycol, 4-9 parts of diethylene glycol and 23-26 parts of neopentyl glycol.

[0023] Furthermore, the triol is trimethylolpropane.

[0024] Furthermore, the esterification catalyst is stannous oxalate.

[0025] Furthermore, the auxiliary agent is the antioxidant auxiliary agent triphenyl phosphite.

[0026] The invention also provides a TMA-free indoor matte polyester resin prepared by the preparation method.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0028] 1. The present invention provides a method for preparing an indoor matte resin that does not contain trimellitic anhydride (TMA) and is used in the solid powder coating industry. By using 1,3,5-cyclohexanetriic acid with a ring structure and low toxicity to replace the old toxic and carcinogenic TMA, the toxicity of the prepared resin is reduced, and the wear resistance, mechanical properties and corrosion resistance of the prepared resin coating are effectively improved.

[0029] 2. The present invention can improve the adhesion of TMA-free indoor matte polyester resin by modifying the polyurethane resin with hydroxyl-terminated methyl vinyl silicone oil.

[0030] 3. The present invention can improve the impact resistance of TMA-free indoor matte polyester resin by modifying three specific fillers.

[0031] 4. The present invention can improve the acetone wiping resistance of the TMA-free indoor matte polyester resin by adding a compounded epoxy resin. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Examples 1-3 and Comparative Examples 1-6

[0034] According to the formula in Table 1, a TMA-free indoor matte polyester resin was prepared.

[0035] The preparation method of the TMA-free indoor matte polyester resin comprises the following steps:

[0036] (1) Add diol, triol and trimethylolpropane in the formula (Table 1) into a reactor, heat to 110°C, and slowly raise the temperature to 240°C; the esterification reaction takes about 48 hours. After the esterification water produced by the reaction is completely discharged, cool down to 220°C in the reactor, add 1,3,5-cyclohexanetricarboxylic acid and auxiliary agents, raise the temperature to 240°C in the reactor, and keep the temperature until the acid value reaches 60-70 mgKOH / g. Then, vacuumize the reactor for 1-2 hours to remove the side reactions, residual monomers and impurities produced in the reaction. After vacuumizing to an acid value of 50-60 mgKOH / g, the discharged material is left to cool to obtain a carboxyl-terminated polyester resin.

[0037] (2) Preparation of polyurethane resin: 42 parts of polyester polyol, 27 parts of hexamethylene diisocyanate, 7 parts of triethylenediamine and 22 parts of hydroxyl-terminated methyl vinyl silicone oil were mixed by weight, heated to 105°C, reacted for 3.5 hours, cooled to room temperature, added with 7 parts of N-methyldiethanolamine, heated to 82°C, reacted for 4 hours, cooled to 32°C, neutralized with glacial acetic acid to a pH of 6.1, added with 49 parts of acetone to dilute, and acetone was removed by vacuum to obtain polyurethane resin;

[0038] The polyester polyols include polyester polyol I, polyester polyol II, and polyester polyol III in a weight ratio of 1:1.5:0.6; the number average molecular weight of polyester polyol I is 600, and the hydroxyl value is 185-205 mgKOH / g; the number average molecular weight of polyester polyol II is 2000, and the hydroxyl value is 53-59 mgKOH / g; the number average molecular weight of polyester polyol III is 4000, and the hydroxyl value is 26-30 mgKOH / g. All of them are purchased from Green Union (Jining) Chemical Technology Co., Ltd.

[0039] Hydroxyl terminated methyl vinyl silicone oil was purchased from Anhui Mingyi Silicon Industry Co., Ltd. Model: Hydroxyl terminated methyl vinyl silicone oil MY 1203V.

[0040] (3) Preparation of modified filler: The preparation method of the modified filler comprises the following steps:

[0041] S1: mixing silicon dioxide, boron carbide and aluminum oxide in a weight ratio of 1:1.5:0.4 to obtain a mixed filler;

[0042] S2: Mix a mixed filler, hexadecyltrimethylammonium bromide, water and sodium chloride in a weight ratio of 10:4.5:16:0.15, adjust the pH value of the system to 8.3, and ball mill for 3.5 hours at a speed of 420 r / min in a ball mill, wash, filter, and vacuum dry to obtain a pre-modified filler;

[0043] S3: The pre-modified filler in a weight ratio of 5:27:1.7, 62% by mass ethanol aqueous solution and polyvinyl alcohol (Henan Wanshan New Material Technology Co., Ltd., brand 27859) were mixed, and the mixture was ball-milled in a ball mill at a speed of 320 r / min for 5.5 h, and then washed, filtered and dried to obtain a modified filler.

[0044] The average particle size of silica is 10 nm and the average specific surface area is 380 m 2 / g, Jinlei Technology, JL-SiO2-N10; the average particle size of boron carbide is 50nm, and the specific surface area is 30-50m 2 / g, Jiangzhiti Nano-Micro New Materials Co., Ltd., ZT-BC60; the average particle size of alumina is 30nm, and the specific surface area is 10-20m 2 / g; Jiangzhiti Nano-Micro New Materials Co., Ltd., ZT-L30G.

[0045] (4) The polyester resin prepared according to step (1) and the raw material dosage recorded in the formula in Table 1 are uniformly mixed with the prepared polyurethane resin, epoxy resin and modified filler according to the formula dosage; the epoxy resin is a composite of epoxy resin I, epoxy resin II and epoxy resin III in a mass ratio of 1.6:1:0.3; the epoxy equivalent of epoxy resin I is 184-194 g / Eq (product brand: Jiangsu Sanmu Group, model: SM 828); the epoxy equivalent of epoxy resin II is 167-175 g / Eq (product brand: Huntsman, model Araldite® GY289), and the epoxy equivalent of epoxy resin III is 400-455 g / Eq (product brand: Huntsman, model Araldite® GY298), to obtain a TMA-free indoor matte polyester resin.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 3 is that the amounts of the polyurethane resin, the epoxy resin and the modified filler are different.

[0048] Comparative Example 2

[0049] The difference between this comparative example and Example 3 is that no hydroxyl-terminated methyl vinyl silicone oil is added in the preparation of the polyurethane resin.

[0050] Preparation of polyurethane resin: By weight, 42 parts of polyester polyol, 27 parts of hexamethylene diisocyanate and 7 parts of triethylenediamine were mixed, heated to 105°C, reacted for 3.5 hours, cooled to room temperature, 7 parts of N-methyldiethanolamine were added, heated to 82°C, reacted for 4 hours, cooled to 32°C, glacial acetic acid was added to neutralize to pH 6.1, 49 parts of acetone were added to dilute, and the acetone was removed by vacuum to obtain a polyurethane resin.

[0051] Comparative Example 3

[0052] The difference between this comparative example and Example 3 is that the epoxy resin is a compound of epoxy resin I, epoxy resin II and epoxy resin III in a mass ratio of 1:1:1, and the epoxy equivalent of epoxy resin I is 184-194 g / Eq (product brand: Jiangsu Sanmu Group, model: SM 828); the epoxy equivalent of epoxy resin II is 167-175 g / Eq (product brand: Huntsman, model Araldite® GY289), and the epoxy equivalent of epoxy resin III is 400-455 g / Eq (product brand: Huntsman, model Araldite® GY298).

[0053] Comparative Example 4

[0054] The difference between this comparative example and Example 3 is that the polyester polyol includes polyester polyol I, polyester polyol II, and polyester polyol III in a weight ratio of 1:1:1; the number average molecular weight of polyester polyol I is 600, and the hydroxyl value is 185-205 mgKOH / g; the number average molecular weight of polyester polyol II is 2000, and the hydroxyl value is 53-59 mgKOH / g; the number average molecular weight of polyester polyol III is 4000, and the hydroxyl value is 26-30 mgKOH / g. All are purchased from Green Union (Jining) Chemical Technology Co., Ltd.

[0055] Comparative Example 5

[0056] The difference between this comparative example and Example 3 is that silicon dioxide, boron carbide and aluminum oxide are mixed in a weight ratio of 1:1:1 to obtain a mixed filler.

[0057] Comparative Example 6

[0058] The difference between this comparative example and Example 3 is:

[0059] The average particle size of silica is 20nm and the average specific surface area is 240m 2 / g, Jinlei Technology, JL-SiO2-N20; the average particle size of boron carbide is 100nm, and the specific surface area is 20-30m 2 / g, Jiangzhiti Nano-Micro New Materials Co., Ltd., ZT-BC100; the average particle size of alumina is 50nm, and the specific surface area is 20-30m 2 / g. Jiangzhiti Nano-Micro New Materials Co., Ltd., ZT-TTGY.

[0060] Table 1 Indoor matte polyester resin formula without TMA (parts by weight)

[0061]

[0062] Performance Test:

[0063] 1. The performance of the TMA-free indoor matte polyester resin prepared in Examples 1-3 was tested. The results are shown in Table 2.

[0064] Table 2 Performance indexes of indoor matte polyester resin without TMA

[0065]

[0066] The performance indicators of the TMA-free indoor matte polyester resin mainly include acid value, viscosity and glass transition temperature (Tg). The acid value of the present invention is determined by KOH titration; the viscosity is determined by a viscometer (CAP1000 + Brookfield / VSA), and the test temperature is 200°C; Tg is determined by a differential scanning calorimeter (DSC200F3 German Netzsch), and the heating rate is 10°C / min. As shown in Table 2, the acid value of the TMA-free indoor matte polyester resin of Examples 1-3 is within the range of 50-60 mgKOH / g, the viscosity is between 1800-3000 mPa.s, and the Tg value is within the range of 50-60°C.

[0067] As shown in the above table, the acid values ​​of the TMA-free indoor matte polyester resins of Examples 1-3 are all between 50-60 mgKOH / g, the viscosities are all greater than 2000 mPa·s, and all have relatively high Tg (greater than 50°C). Moreover, as the content of 1,3,5-cyclohexanetricarboxylic acid in the resin formula decreases, the viscosity and glass transition temperature of the prepared resin decrease to a certain extent, further verifying the role of 1,3,5-cyclohexanetricarboxylic acid in the resin.

[0068] Acid value is one of the important factors affecting the matting ability of polyester. The higher the acid value of the TMA-free indoor matting polyester resin, the higher the density of the network cross-linked structure in the curing system. This network structure will hinder the rapid diffusion of other additives in the formula in the resin matrix, including the matting agent, thereby affecting its destructive effect on the flatness of the coating, and ultimately affecting the matting performance of the powder coating. The acid value of the TMA-free indoor matting polyester resin of the present invention is mainly between 50-60 mgKOH / g, which is similar to the acid value range of commercially available matting resins and has a suitable acid value.

[0069] Among the several important parameters for characterizing polyester resins for powder coatings, resin viscosity is one of the key parameters. The size of the resin viscosity directly affects the appearance smoothness of the powder coating. Relevant data show that when preparing indoor matte mixed powder coatings, the size of the viscosity will also affect the matte performance of the powder coating. The viscosity of the commonly used matte polyester resin is in the range of 1800mPa·s-3000mPa·s, and the matte gloss of the corresponding powder coating increases with the increase of viscosity. The reason is that the lower the resin viscosity, the more conducive it is to the dispersion of pigments, fillers and additives in the resin matrix. As shown in Table 2, with the increase of the content of 1,3,5-cyclohexanetricarboxylic acid in the resin, the viscosity of the synthetic polyester resin also shows an increasing trend, and all synthetic resins have a suitable viscosity. Although reducing the viscosity of the resin is conducive to improving the matte performance of the powder, low viscosity will also be accompanied by a negative effect, that is, the Tg of the resin is low. In order to take into account the storage stability of the powder coating and prevent the powder coating from agglomerating due to high temperature during storage, certain requirements must be placed on the Tg of the synthetic resin. The synthetic resins prepared by the present invention all have relatively high Tg (all greater than 52° C.), and 1,3,5-cyclohexanetriolic acid has a certain positive effect on improving the Tg of the resin.

[0070] 2. Powder coatings were prepared using the TMA-free indoor matte polyester resins prepared in Examples 1-3 and Comparative Examples 1-6, and the formula is shown in Table 3. Leveling agent (analytical grade) and benzoin (analytical grade) were purchased from Anhui Jiayue Surface Technology Co., Ltd.; matte barium sulfate and titanium dioxide 996 were purchased from Shanghai Haocen Chemical Co., Ltd.; physical matte agent SA2065K was purchased from Lu'an Jietongda New Materials Co., Ltd.

[0071] Table 3 Preparation formula of powder coating (parts by weight)

[0072]

[0073] All raw materials of powder coating were premixed, extruded, sheeted and crushed by a twin-screw extruder, and then the sheet was crushed and passed through a 200-mesh sieve, and then sprayed on an aluminum plate by electrostatic spraying, cured at 200°C for 10 minutes, and then the performance test was carried out. The formula of the powder coating is shown in Table 3. The gloss of the present invention is measured by a gloss meter (BYGardnerGmbH, Germany, 60°), and the impact resistance is measured according to GB / T1732-2020; the leveling property of the coating of the present invention is measured according to the national standard GB / T1750-1979 coating leveling property measurement method; the adhesion of the coating is measured according to the national standard GB / T9286-2021 color paint and varnish cross-cutting test; the surface of the coating is detected according to the national standard GB / T 27808-2011 thermosetting powder coating with saturated polyester resin method; the gel time of the coating is measured according to the method described in the national standard GB / T16995-1997; the pencil hardness of the coating is measured according to the method described in the national standard GB / T6739-2022 color paint and varnish pencil method for measuring the hardness of the paint film; the acetone resistance of the coating is measured by the GB / T 23989-2009 coating solvent resistance wiping measurement method, with a total of 25 reciprocating wiping times.

[0074] The results are shown in Table 4.

[0075] Table 4 Performance indexes of various synthetic resin coatings

[0076]

[0077] It can be seen from the above table that different contents of 1,3,5-cyclohexanetricarboxylic acid in the prepared powder coating have a certain influence on the gelation time. This is because 1,3,5-cyclohexanetricarboxylic acid can react to form a network structure, promote the gelation of the coating, and make the required gelation time relatively low. It can be seen from Table 4 that the coatings of Examples 1-3 have certain matting properties; the coating leveling can reach level 5 or 6, and the leveling is good; the chemical resistance is good; the adhesion is all level 0; the prepared films can pass 50Kg.cm front and back impacts, and the impact resistance is good; the coating of Example 1 has a slightly heavier orange peel appearance, and the coatings of Examples 2 and 3 are slightly orange peel. This is because the presence of the matting agent will make the coating surface uneven, increase the scattering of light and reduce reflection, thereby reducing the gloss of the coating, but will destroy the smoothness and continuity of the coating surface to a certain extent, and the network structure formed by 1,3,5-cyclohexanetriac acid in the resin will hinder the uniform dispersion of the matting agent to a certain extent, reduce the gloss of the coating, and further affect the smoothness and continuity of the coating surface. As shown in the leveling property in Table 4, the leveling property of Example 1 is worse than that of Examples 2 and 3 due to the increase in the content of 1,3,5-cyclohexanetriac acid.

[0078] In Comparative Example 1, the proportions of polyurethane resin, epoxy resin and modified filler are different, and the comprehensive performance of the coating powder is reduced. In Comparative Example 2, hydroxyl-terminated methyl vinyl silicone oil is not used to modify the polyurethane resin. In Comparative Example 4, the polyester polyol ratio is different, and the adhesion of the coating powder is reduced. In Comparative Example 3, the epoxy resin ratio is different, and the acetone wiping resistance of the coating powder is reduced. The composition of the filler in Comparative Example 5 is different and the filler parameters in Comparative Example 6 are different, and the impact resistance of the powder coating is reduced. The above experimental results further prove the importance of the technical solution defined in the present invention for its technical effect.

[0079] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a TMA-free indoor matte polyester resin, characterized in that: The method comprises the following steps: (1) preparing a carboxyl-terminated polyester resin: putting a diol, a triol and trimethylolpropane into a reaction kettle and starting stirring; adding terephthalic acid and an esterification catalyst, slowly heating the temperature to 220-240°C; adding 1,3,5-cyclohexanetricarboxylic acid and an auxiliary agent, reacting until the acid value reaches 50-60 mgKOH / g, and letting the discharged material stand and cool to obtain the obtained product; (2) preparing a polyurethane resin: mixing 40-45 parts of polyester polyol, 26-29 parts of hexamethylene diisocyanate, 6-9 parts of triethylenediamine and 20-25 parts of hydroxyl-terminated methyl vinyl silicone oil by weight, heating the mixture to 100-110°C, reacting the mixture for 3-4 hours, cooling the mixture to room temperature, adding 6-8 parts of N-methyldiethanolamine, heating the mixture to 80-85°C, reacting the mixture for 3-5 hours, cooling the mixture to 30-35°C, and adding glacial acetic acid to neutralize the mixture to a pH of 1. 6-6.2, add 48-50 parts of acetone to dilute, and remove the acetone in vacuo to obtain; (3) evenly mix the carboxyl-terminated polyester resin, polyurethane resin, epoxy resin and modified filler to obtain a TMA-free indoor matte polyester resin; The modified filler preparation method comprises: S1: Mix silicon dioxide, boron carbide and aluminum oxide to obtain a mixed filler; S2: Mix a mixed filler in a weight ratio of 10: (4-5): (15-18): (0.1-0.2), hexadecyltrimethylammonium bromide, water and sodium chloride, adjust the pH to 8.2-8.5, and ball mill in a ball mill at a speed of 400-450r / min for 3-4h, wash, filter, and vacuum dry to obtain a pre-modified filler; S3: Mix a pre-modified filler in a weight ratio of 5: (25-30): (1.5-2), a 60-65wt% ethanol aqueous solution and polyvinyl alcohol, and ball mill in a ball mill at a speed of 300-350r / min for 5-6h, wash, filter, and dry to obtain a modified filler; The polyester polyol comprises polyester polyol I, polyester polyol II and polyester polyol III in a weight ratio of 1: (1.4-1.6): (0.5-0.7); the number average molecular weight of polyester polyol I is 600, and the hydroxyl value is 185-205 mgKOH / g; the number average molecular weight of polyester polyol II is 2000, and the hydroxyl value is 53-59 mgKOH / g; the number average molecular weight of polyester polyol III is 4000, and the hydroxyl value is 26-30 mgKOH / g; The mixed filler is obtained by mixing silicon dioxide, boron carbide and aluminum oxide in a weight ratio of 1: (1.4-1.6): (0.2-0.5); the average particle size of silicon dioxide is 10 nm and the average specific surface area is 380 m 2 / g; the average particle size of boron carbide is 50nm, and the specific surface area is 30-50m 2 / g; the average particle size of alumina is 30nm, and the specific surface area is 10-20m 2 / g; The epoxy resin is a compound of epoxy resin I, epoxy resin II and epoxy resin III in a mass ratio of (1.5-1.7):1:(0.2-0.4), the epoxy equivalent of epoxy resin I is 184-194 g / Eq; the epoxy equivalent of epoxy resin II is 167-175 g / Eq, and the epoxy equivalent of epoxy resin III is 400-455 g / Eq.

2. The method for preparing the TMA-free indoor matte polyester resin according to claim 1, characterized in that: In step (1), the steps of preparing the carboxyl-terminated polyester resin are as follows: 25-30 parts of diol, 1-3 parts of triol and 1-4 parts of trimethylolpropane are added into a reaction kettle, heated and stirred; 60-70 parts of terephthalic acid and an esterification catalyst are added, and the temperature is slowly raised to 240°C; the esterification reaction takes 48 hours, and after the esterification water generated by the reaction is completely discharged, the temperature is lowered to 220°C in the kettle, and 1,3,5-cyclohexanetricarboxylic acid and an auxiliary agent are added, the temperature is raised to 240°C in the kettle, and the temperature is kept at 60-70 mgKOH / g to an acid value, and then the reaction kettle is vacuumed for 1-2 hours to remove side reactions, residual monomers and impurities generated in the reaction, and after vacuuming to an acid value of 50-60 mgKOH / g, the discharged material is allowed to stand and cool to obtain the carboxyl-terminated polyester resin.

3. The method for preparing the TMA-free indoor matte polyester resin according to claim 1, characterized in that: The carboxyl-terminated polyester resin, 18-23 parts of polyurethane resin, 32-37 parts of epoxy resin and 8-12 parts of modified filler are uniformly mixed according to the formula amount to obtain a TMA-free indoor matte polyester resin.

4. The method for preparing the TMA-free indoor matte polyester resin according to claim 1, characterized in that: The diol comprises 12-16 parts of ethylene glycol, 4-9 parts of diethylene glycol and 23-26 parts of neopentyl glycol; the triol is trimethylolpropane; the esterification catalyst is stannous oxalate; and the auxiliary agent is triphenyl phosphite.

5. A TMA-free indoor matte polyester resin prepared according to the preparation method according to any one of claims 1 to 4.

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