Anti-ultraviolet epoxy resin coating and preparation method thereof

Abstract

The invention discloses an anti-ultraviolet epoxy resin coating and a preparation method thereof, and belongs to the technical field of epoxy resin coatings. Comprising a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 80-90 parts of bisphenol A epoxy resin, 5-8 parts of a reactive diluent, 10-15 parts of modified titanium dioxide, 2-6 parts of an anti-ultraviolet agent, 0.2-0.5 part of a defoaming agent and 0.2-0.5 part of a flatting agent. And the component B is a curing agent. The modified titanium dioxide and the self-made anti-ultraviolet agent are introduced, and the modified titanium dioxide and the self-made anti-ultraviolet agent can achieve a synergistic effect, so that the anti-ultraviolet performance of the coating is remarkably improved; wherein the modified titanium dioxide has better compatibility with an epoxy resin matrix, the dispersion is more uniform, and the problem that traditional inorganic nanoparticles are easy to agglomerate is avoided; in conclusion, the prepared coating has stable and efficient anti-ultraviolet performance and has important application value in the field of epoxy resin coatings.

Description

Technical Field

[0002] This invention belongs to the field of epoxy resin coating technology, specifically, it relates to an anti-ultraviolet epoxy resin coating and its preparation method. Background Technology

[0003] In the coatings industry, epoxy resins have long been widely used in many key areas such as metal protection, automotive primers, industrial flooring, electronic packaging, and aerospace due to their excellent adhesion, mechanical strength, chemical corrosion resistance, and good insulation properties. However, traditional epoxy resin coatings also have some inherent defects, one of the most prominent being their poor weather resistance, especially their insufficient resistance to ultraviolet rays from sunlight. The aromatic ether and ester functional groups in the epoxy resin molecule are extremely sensitive to ultraviolet light, and are prone to photo-oxidative degradation under long-term outdoor sunlight exposure. This leads to phenomena such as chalking, loss of gloss, discoloration, embrittlement, and even peeling of the coating, which not only seriously affects the appearance and decorative properties of the material but also greatly weakens its inherent protective function and service life. This limitation restricts the application of epoxy resins in high-standard outdoor protection scenarios, such as bridge steel structures exposed to strong sunlight for extended periods, outdoor wind power equipment, ship superstructures, and certain special occasions with extreme requirements for coating durability.

[0004] To improve the UV resistance of epoxy resins, the industry has conducted extensive research and technological exploration. Conventional modification methods mainly involve physical blending with inorganic UV-blocking agents. Physical blending is relatively simple, and commonly used additives include nano-titanium dioxide and nano-zinc oxide. These additives, by reflecting, scattering, or absorbing UV rays, can delay the damage of UV rays to the resin matrix to some extent. However, this method also has significant drawbacks: inorganic nanoparticles are prone to agglomeration in the resin matrix, making uniform dispersion difficult, which affects the transparency and mechanical properties of the coating and may create stress concentration points. Therefore, it is urgent to solve these problems to meet the higher demands of the epoxy resin coating industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an anti-ultraviolet epoxy resin coating and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions: An anti-ultraviolet epoxy resin coating, comprising component A and component B.

[0007] As a further technical solution, component A comprises the following raw materials in parts by weight: 80-90 parts bisphenol A epoxy resin, 5-8 parts reactive diluent, 10-15 parts modified titanium dioxide, 2-6 parts UV stabilizer, 0.2-0.5 parts defoamer and 0.2-0.5 parts leveling agent.

[0008] As a further technical solution, component B is a curing agent.

[0009] As a further technical solution, the weight ratio of component A to component B is 100:35.

[0010] As a further technical solution, the active diluent is benzyl glycidyl ether.

[0011] As a further technical solution, the defoamer is an organosilicon defoamer.

[0012] As a further technical solution, the leveling agent is an acrylate leveling agent.

[0013] As a further technical solution, the modified titanium dioxide is prepared through the following steps: A1. Add nano titanium dioxide to a flask, then add hydrogen peroxide dropwise. After stirring and mixing evenly, heat to 50-70℃ and keep the temperature for 4-6 hours. After the reaction is complete, filter and dry to obtain hydroxylated titanium dioxide. A2. The hydroxylated titanium dioxide obtained in step A1 is mixed with acetone and silane coupling agent KH-550, heated to 70-80℃, and reacted for 4-6 hours. After the reaction is complete, the mixture is filtered and vacuum dried to obtain modified titanium dioxide.

[0014] As a further technical solution, the raw materials are as follows by weight: 10-20 parts nano titanium dioxide, 25-35 parts hydrogen peroxide, 50-60 parts acetone, and 2-4 parts silane coupling agent KH-550.

[0015] Nano titanium dioxide possesses excellent UV resistance. Through modification, it exhibits better compatibility with epoxy resins and is more easily dispersed in the matrix compared to ordinary nano titanium dioxide, allowing its performance to be fully realized and significantly enhancing the UV resistance of the matrix.

[0016] As a further technical solution, the UV stabilizer is prepared through the following steps: B1. In a three-necked flask, first add 2,2',4,4'-tetrahydroxybenzophenone, 3-chloropropylamine, and toluene. After stirring and mixing thoroughly, purge the air from the apparatus with nitrogen. Then, use a constant-pressure dropping funnel to add sodium hydroxide solution (12% by mass) dropwise to the three-necked flask. Heat the apparatus until the temperature reaches 70-75°C, maintain this temperature, and stir the reaction for 4-5 hours. After the reaction is complete, cool to room temperature, separate the aqueous phase, wash the organic phase with dilute hydrochloric acid until neutral, dry with anhydrous sodium sulfate, remove toluene by vacuum evaporation, recrystallize with ethanol-water, and dry under vacuum at 60-80°C to obtain the primary product. B2. In a three-necked flask, first add the primary product, benzothiazole-2-carboxaldehyde, and toluene. Stir and mix thoroughly, then purge the air from the apparatus with nitrogen. Subsequently, heat to 80-85°C and stir continuously for 10 hours until the reaction is complete. Cool to room temperature, filter and collect the solid, wash with cold toluene, recrystallize with hot ethanol, and dry under vacuum at 50-60°C to obtain the UV stabilizer.

[0017] As a further technical solution, in step B1, the ratio of the amounts of 2,2',4,4'-tetrahydroxybenzophenone, 3-chloropropylamine, and sodium hydroxide solution is 25.9-27.1 g: 18.6 g: 30 mL.

[0018] As a further technical solution, the ratio of the initial product to benzothiazole-2-carboxaldehyde in step B2 is 36.0g:33.7-35.4g.

[0019] The reaction formula for preparing the UV protectant in this invention is as follows:

[0020] In this invention, to obtain the UV-resistant agent in the above reaction formula, it is necessary to strictly control the amount of each step. In step B1, 2,2',4,4'-tetrahydroxybenzophenone and 3-chloropropylamine undergo a nucleophilic substitution reaction under the catalysis of sodium hydroxide. The molar ratio of the two is controlled to be close to 1:2, and the former is in excess. In step B2, the initial product undergoes a condensation reaction with benzothiazole-2-carboxaldehyde to generate a Schiff base product. The molar ratio of the two is controlled to be close to 1:2, and the latter is in excess, to reduce the production of side reactions and finally obtain the UV-resistant agent.

[0021] The UV stabilizer prepared by this invention, as can be seen from the structure of the above reaction formula, possesses a benzophenone structure. Benzophenone can absorb ultraviolet light and convert it into harmless heat energy, thereby protecting materials from UV damage. Furthermore, the UV stabilizer molecule also contains a benzothiazole structure. Due to its special nitrogen- and sulfur-containing heterocyclic structure, this structure can play a certain curing role in epoxy resin systems, not only promoting epoxy resin curing but also significantly enhancing the migration resistance of the UV stabilizer. Compared with traditional small-molecule UV stabilizers, its stability is greater.

[0022] This invention also provides a method for preparing an anti-ultraviolet epoxy resin coating, comprising the following steps: C1. In a mixing tank, add bisphenol A epoxy resin and reactive diluent, start low-speed stirring, then add defoamer and leveling agent in sequence, continue stirring for 10-15 minutes, then add modified titanium dioxide and increase the stirring speed to high speed for 30-40 minutes to ensure that the raw materials are completely and evenly dispersed to obtain a mixture. C2. Transfer the mixture to a three-roll mill for grinding and dispersion. Transfer the ground slurry back to the mixing tank, resume low-speed stirring, add UV stabilizer, and continue stirring for 20-30 minutes to ensure all components are mixed evenly. Filter with a screen to obtain component A. C3. When using, mix component A and component B to obtain an anti-UV epoxy resin coating.

[0023] As a further technical solution, the rotation speed of the low-speed stirring is 400-500 r / min.

[0024] As a further technical solution, the high-speed stirring speed is 1000-1200 r / min.

[0025] As a further technical solution, the mesh size of the filter screen is 100-200 mesh.

[0026] The beneficial effects of this invention are: Advantage 1: By introducing modified titanium dioxide and self-made anti-UV agent, the two can play a synergistic role, which significantly improves the coating's ability to absorb, reflect and scatter ultraviolet rays, effectively delays the photo-oxidative degradation of epoxy resin, and prevents problems such as coating chalking, discoloration and embrittlement. Advantage 2: The modified titanium dioxide has better compatibility with the epoxy resin matrix and is more uniformly dispersed, avoiding the problem of easy agglomeration of traditional inorganic nanoparticles, and improving the transparency and mechanical properties of the coating. Advantage 3: The UV stabilizer also contains a benzothiazole structure, which can participate in the curing reaction in the epoxy resin system, enhance the crosslinking density and migration resistance of the coating, and improve long-term stability; Advantage 4: The preparation method of this invention is simple to operate and easy to industrialize; In summary, the coating prepared by this invention has stable and efficient UV protection properties and is easy to industrialize, thus possessing significant application value in the field of epoxy resin coatings. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 Preparation of modified titanium dioxide: A1. Add 10 parts of nano titanium dioxide to a flask, then add 25 parts of hydrogen peroxide dropwise. After stirring and mixing evenly, heat to 50°C and keep the temperature for 4 hours. After the reaction is complete, filter and dry to obtain hydroxylated titanium dioxide. A2. The hydroxylated titanium dioxide obtained in step A1 is mixed with 50 parts of acetone and 2 parts of silane coupling agent KH-550, heated to 70°C, and reacted for 4 hours. After the reaction is complete, the mixture is filtered and dried under vacuum to obtain modified titanium dioxide.

[0029] Example 2 Preparation of modified titanium dioxide: A1. Add 20 parts of nano titanium dioxide to a flask, then add 35 parts of hydrogen peroxide dropwise. After stirring and mixing evenly, heat to 70°C and keep the temperature for 6 hours. After the reaction is complete, filter and dry to obtain hydroxylated titanium dioxide. A2. The hydroxylated titanium dioxide obtained in step A1 was mixed with 60 parts of acetone and 4 parts of silane coupling agent KH-550, heated to 80°C, and reacted for 6 hours. After the reaction was completed, the mixture was filtered and dried under vacuum to obtain modified titanium dioxide.

[0030] Example 3 Preparation of UV protectants: B1. In a three-necked flask, first add 25.9 g of 2,2',4,4'-tetrahydroxybenzophenone, 18.6 g of 3-chloropropylamine, and 100 mL of toluene. After stirring and mixing thoroughly, purge the air from the apparatus with nitrogen. Then, using a constant pressure dropping funnel, add 30 mL of sodium hydroxide solution (12% by mass) dropwise to the three-necked flask. Heat the apparatus until the temperature reaches 70 °C, maintain this temperature, and stir the reaction for 4 hours. After the reaction is complete, cool to room temperature, separate the aqueous phase, wash the organic phase with dilute hydrochloric acid until neutral, dry with anhydrous sodium sulfate, remove toluene by vacuum evaporation, recrystallize with ethanol-water, and dry under vacuum at 60-80 °C to obtain the primary product. B2. In a three-necked flask, first add 36.0 g of the initial product, 33.7 g of benzothiazole-2-carboxaldehyde and 120 mL of toluene. After stirring and mixing evenly, nitrogen gas is introduced to purge the air from the apparatus. Then, heat it to 80 °C and stir continuously for 10 h until the reaction is complete. Cool to room temperature, filter and collect the solid, wash with cold toluene, recrystallize with hot ethanol, and dry under vacuum at 50 °C to obtain the UV stabilizer. A method for preparing an anti-ultraviolet epoxy resin coating includes the following steps: C1. In a mixing tank, add 80 parts of bisphenol A epoxy resin E-51 and 5 parts of benzyl glycidyl ether, and stir at a low speed of 400-500 r / min. Then add 0.2 parts of defoamer (BYK-022) and 0.2 parts of leveling agent (BYK-358) in sequence. After stirring for 10 min, add 10 parts of modified titanium dioxide prepared in Example 1, and increase the stirring speed to 1000 r / min for 30 min to ensure that the raw materials are completely and evenly dispersed to obtain a mixture. C2. Transfer the mixture to a three-roll mill for grinding and dispersion. Transfer the ground slurry back to the mixing tank and stir at a low speed of 400 r / min. Add 2 parts of UV stabilizer and continue stirring for 20 min to ensure that all components are mixed evenly. Filter with a 100-mesh filter to obtain component A. C3. When using, mix component A and component B at a weight ratio of 100:35 to obtain an anti-UV epoxy resin coating.

[0031] Example 4 Preparation of UV protectants: B1. In a three-necked flask, first add 27.1g of 2,2',4,4'-tetrahydroxybenzophenone, 18.6g of 3-chloropropylamine, and 100mL of toluene. After stirring and mixing thoroughly, purge the air from the apparatus with nitrogen. Then, using a constant pressure dropping funnel, add 30mL of sodium hydroxide solution (12% by mass) dropwise to the three-necked flask. Heat the apparatus until the temperature reaches 75°C, maintain this temperature, and stir the reaction for 5 hours. After the reaction is complete, cool to room temperature, separate the aqueous phase, wash the organic phase with dilute hydrochloric acid until neutral, dry with anhydrous sodium sulfate, remove toluene by vacuum evaporation, recrystallize with ethanol-water, and dry under vacuum at 60-80°C to obtain the primary product. B2. In a three-necked flask, first add 36.0 g of the initial product, 35.4 g of benzothiazole-2-carboxaldehyde and 120 mL of toluene. After stirring and mixing evenly, nitrogen gas is introduced to purge the air from the apparatus. Then, heat it to 85 °C and stir continuously for 10 h until the reaction is complete. Cool to room temperature, filter and collect the solid, wash with cold toluene, recrystallize with hot ethanol, and dry under vacuum at 60 °C to obtain the UV stabilizer. A method for preparing an anti-ultraviolet epoxy resin coating includes the following steps: C1. In a mixing tank, add 85 parts of bisphenol A epoxy resin E-51 and 6.5 parts of benzyl glycidyl ether, and stir at a low speed of 400 r / min. Then add 0.2 parts of defoamer (BYK-022) and 0.2 parts of leveling agent (BYK-358) in sequence. After stirring for 10 min, add 10 parts of modified titanium dioxide prepared in Example 2, and increase the stirring speed to 1000 r / min for 30 min to ensure that the raw materials are completely and evenly dispersed to obtain a mixture. C2. Transfer the mixture to a three-roll mill for grinding and dispersion. Transfer the ground slurry back to the mixing tank and stir at a low speed of 400 r / min. Add 4 parts of UV stabilizer and continue stirring for 25 min to ensure that all components are mixed evenly. Filter with a 200 mesh screen to obtain component A. C3. When using, mix component A and component B at a weight ratio of 100:35 to obtain an anti-UV epoxy resin coating.

[0032] Example 5 The only difference between this embodiment and Embodiment 4 is that, in this embodiment, a method for preparing an anti-UV epoxy resin coating includes the following steps: C1. In a mixing tank, add 90 parts of bisphenol A epoxy resin E-51 and 8 parts of benzyl glycidyl ether, and stir at a low speed of 500 r / min. Then add 0.5 parts of defoamer (BYK-022) and 0.5 parts of leveling agent (BYK-358) in sequence. After stirring for 15 min, add 15 parts of modified titanium dioxide prepared in Example 2, and increase the stirring speed to 1200 r / min for 30-40 min to ensure that the raw materials are completely and evenly dispersed to obtain a mixture. C2. Transfer the mixture to a three-roll mill for grinding and dispersion. Transfer the ground slurry back to the mixing tank and stir at a low speed of 500 r / min. Add 6 parts of UV stabilizer and continue stirring for 30 min to ensure that all components are mixed evenly. Filter with a 200-mesh filter to obtain component A. C3. When using, mix component A and component B at a weight ratio of 100:35 to obtain an anti-UV epoxy resin coating.

[0033] Comparative Example 1 The only difference between this comparative example and Example 5 is that in this comparative example, an equal amount of UV absorber BP-2 was used to replace the UV stabilizer to prepare the coating.

[0034] Comparative Example 2 The only difference between this comparative example and Example 5 is that in this comparative example, an equal amount of nano-titanium dioxide was used to replace the modified titanium dioxide to prepare the coating.

[0035] The following performance tests were conducted on Examples 3, 4, and 5, and Comparative Examples 1 and 2: The appearance of the samples after aging was determined and the powdering grade was evaluated according to the GB / T 1865-2009 standard. The color difference of the samples after aging was determined according to GB / T 1766-2008 standard. After Examples 3, 4, and 5 and Comparative Example 1 were left to stand at room temperature for 365 days, the pulverization level was evaluated according to the GB / T 1865-2009 standard. The results of the performance tests are shown in Table 1: Table 1

[0036] As can be seen from the table above, the coating prepared in the embodiments of the present invention has stable and efficient UV protection properties, and has important application value in the field of epoxy resin coatings.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A UV-resistant epoxy resin coating, characterized in that, It includes component A and component B; wherein component A comprises the following raw materials in parts by weight: 80-90 parts bisphenol A epoxy resin, 5-8 parts reactive diluent, 10-15 parts modified titanium dioxide, 2-6 parts UV stabilizer, 0.2-0.5 parts defoamer and 0.2-0.5 parts leveling agent; and component B is a curing agent.

2. The UV-resistant epoxy resin coating according to claim 1, characterized in that, The modified titanium dioxide is prepared by the following steps: A1. Add nano titanium dioxide to a flask, then add hydrogen peroxide dropwise. After stirring and mixing evenly, heat to 50-70℃ and keep the temperature for 4-6 hours. Once the reaction is complete, hydroxylated titanium dioxide is obtained. A2. The hydroxylated titanium dioxide obtained in step A1 is mixed with acetone and silane coupling agent KH-550, and then heated to 70-80℃ and reacted for 4-6 hours. The reaction is completed, and modified titanium dioxide is obtained.

3. The UV-resistant epoxy resin coating according to claim 2, characterized in that, The raw materials are as follows by weight: 10-20 parts nano titanium dioxide, 25-35 parts hydrogen peroxide, 50-60 parts acetone, and 2-4 parts silane coupling agent KH-550.

4. The UV-resistant epoxy resin coating according to claim 1, characterized in that, The UV stabilizer is prepared by the following steps: B1. In a flask, first add 2,2',4,4'-tetrahydroxybenzophenone, 3-chloropropylamine and toluene, stir, then purge with nitrogen gas, add sodium hydroxide solution dropwise, and react at 70-75℃ for 4-5 hours. The reaction is complete, and the initial product is obtained. B2. In a flask, first add the initial product, benzothiazole-2-carboxaldehyde and toluene, stir, then introduce nitrogen gas, and react at 80-85℃ for 10 hours. Once the reaction is complete, the UV stabilizer is obtained.

5. The UV-resistant epoxy resin coating according to claim 4, characterized in that, In step B1, the ratio of 2,2',4,4'-tetrahydroxybenzophenone, 3-chloropropylamine, and sodium hydroxide solution is 25.9-27.1 g: 18.6 g: 30 mL.

6. The UV-resistant epoxy resin coating according to claim 4, characterized in that, In step B2, the ratio of the initial product to benzothiazole-2-carboxaldehyde is 36.0 g: 33.7-35.4 g.

7. The UV-resistant epoxy resin coating according to claim 1, characterized in that, The weight ratio of component A to component B is 100:

35.

8. The UV-resistant epoxy resin coating according to claim 1, characterized in that, The active diluent is benzyl glycidyl ether.

9. The UV-resistant epoxy resin coating according to claim 1, characterized in that, The defoamer is an organosilicon defoamer.

10. A method for preparing an anti-ultraviolet epoxy resin coating, used to prepare the anti-ultraviolet epoxy resin coating according to any one of claims 1-9, characterized in that, Includes the following steps: C1. In a mixing tank, add bisphenol A epoxy resin and reactive diluent, start low-speed stirring, then add defoamer and leveling agent in sequence, continue stirring for 10-15 minutes, then add modified titanium dioxide, stir at high speed for 30-40 minutes to obtain a mixture. C2. After grinding and dispersing the mixture, add the UV stabilizer while stirring at low speed, continue stirring for 20-30 minutes, filter with a filter screen to obtain component A; C3. When using, mix component A and component B to obtain an anti-UV epoxy resin coating.

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