Hyperbranched epoxy resin with improved epoxy coating protection performance and preparation method thereof

Abstract

The invention discloses hyperbranched epoxy resin with improved protection performance of an epoxy coating, which is prepared by the following steps: (1) by taking an allyl-terminated acrylate compound as a core and 1, 4-pentadiene-3-alcohol as a chain extender, carrying out chain extension under the conditions of a catalyst, heating and argon protection to prepare hyperbranched polyester ether; and (2) dissolving the hyperbranched polyester ether, an initiator and a chain growth control agent in xylene, and under the conditions of heating and nitrogen protection, terminating with allyl glycidyl ether to prepare the hyperbranched epoxy resin. The hyperbranched epoxy resin prepared through Michael addition polymerization reaction has the characteristics of less molecular winding, low viscosity and high solubility, and can be used as epoxy coating matrix resin to accelerate the low-temperature curing speed of a coating, enhance the adhesive force, water resistance and salt spray resistance, and improve the overall protection performance of the epoxy coating in a severe environment.

Description

Technical Field

[0001] This invention belongs to the field of resin synthesis technology, specifically relating to a hyperbranched epoxy resin with improved protective performance of epoxy coating and its preparation method. Background Technology

[0002] Epoxy coatings are widely used in metal corrosion protection, building protection, and electronic packaging due to their excellent adhesion, chemical stability, and mechanical properties. However, traditional linear epoxy resins still have significant shortcomings in practical applications: their regular molecular chain structure and high crosslinking density lead to the formation of rigid networks within the coating. When subjected to external impacts or temperature changes, stress concentration can easily cause microcracks, thereby compromising the integrity of the coating. Meanwhile, the coating formed after linear epoxy resin curing has limited density. Corrosive media such as water molecules, oxygen, and chloride ions can easily penetrate to the substrate surface through the pores or defects in the coating, causing metal corrosion or substrate aging and severely shortening the protective life of the coating. Especially in highly corrosive environments such as marine and chemical industries, traditional epoxy coatings often fail to meet long-term protection requirements and are prone to failure phenomena such as blistering and peeling. Therefore, developing a novel epoxy resin with excellent performance that can significantly improve the protective properties of epoxy coatings has become an important problem that urgently needs to be solved in the field of resin synthesis. Summary of the Invention

[0003] To address the performance issues of linear epoxy coatings, the present invention aims to provide a method for preparing a hyperbranched epoxy resin that enhances the protective performance of epoxy coatings. Epoxy coatings prepared using the resin provided by this invention exhibit rapid low-temperature curing, strong water and salt spray resistance, and provide long-term protection to the substrate in harsh environments.

[0004] To achieve the above-mentioned objective, the present invention provides a method for preparing a hyperbranched epoxy resin with improved protective performance of epoxy coating, comprising the following steps: (1) The terminal allyl acrylate compound and 1,4-pentadien-3-ol are reacted under argon protection, catalysis of phosphazene base catalyst and temperature of 10-40℃ for 1-3h. Then dilute hydrochloric acid is added to terminate the reaction. After the reaction is terminated, sodium hydroxide is added to neutralize the added dilute hydrochloric acid. Then water is added for washing. After washing, the organic phase and inorganic phase are separated. The organic phase is dried to remove residual water, and then hyperbranched polyester ether is obtained. The mass concentration of dilute hydrochloric acid is generally 0.5mol / L-1mol / L. The separation of organic phase and inorganic phase can be achieved by membrane filtration. The reaction temperature is preferably 15℃-30℃, and more preferably 20℃-25℃.

[0005] (2) The hyperbranched polyester ether, initiator, chain growth control agent, and solvent are mixed. Under nitrogen protection at a temperature of 75℃~95℃, the mixture of allyl glycidyl ether and solvent is slowly added dropwise. After the addition is complete, the reaction continues for 2-4 hours under nitrogen protection at 75℃~95℃. After the reaction is complete, the solvent is removed to obtain the hyperbranched epoxy resin. Mixing the hyperbranched polyester ether, initiator, chain growth control agent, and solvent is to ensure good fluidity of the reaction system, facilitating complete reaction. The amount of solvent used in this step is generally 20%-50% of the mass of the hyperbranched polyester ether. Preparing the mixture of allyl glycidyl ether and solvent is also to ensure good fluidity of the allyl glycidyl ether, facilitating the dropwise addition operation. The amount of solvent used is generally 10%-40% of the mass of the allyl glycidyl ether. The slow dropwise addition time is generally 20-30 minutes. The preferred reaction temperature is 80℃-85℃.

[0006] The terminal allyl acrylate compound is pentaerythritol tetraacrylate or pentaerythritol tetramethacrylate.

[0007] The mass ratio of the terminal allyl acrylate compound to 1,4-pentadien-3-ol is 1:2.8-1:3.2, preferably 1:2.8-1:3.0; the amount of phosphazene base catalyst is 0.5%-1.5% of the total mass of the terminal allyl acrylate compound and 1,4-pentadien-3-ol, preferably 0.8%-1.2%.

[0008] The phosphazene alkaline catalyst is any one or a mixture of two or more of t-BuP1, t-BuP2, and t-BuP4 in any mass ratio. Further preferred are t-BuP1 or t-BuP2, and even more preferred are t-BuP2.

[0009] The initiator is one or a mixture of two of azobisisobutyronitrile and azobisisoheptanenitrile in any mass ratio.

[0010] The chain growth control agent is alpha-methylstyrene dimer.

[0011] The mass ratio of allyl glycidyl ether to hyperbranched polyester ether is 1:1.4-1:1.6, preferably 1:1.4-1:1.5; the amount of initiator is 0.2%-2% of the total mass of allyl glycidyl ether and hyperbranched polyester ether, preferably 0.4%-1.2%; the amount of chain growth control agent is 0.3%-1.2% of the total mass of allyl glycidyl ether and hyperbranched polyester ether, preferably 0.5%-1.0%.

[0012] The solvent mentioned in step (2) is one or a mixture of two or more of toluene, xylene, propylene glycol methyl ether, and butyl acetate in any proportion.

[0013] The beneficial effects of this invention are as follows: Through Michael addition polymerization, hydroxyl and allyl groups react rapidly at a lower temperature, resulting in an ether bond structure that enhances the flexibility and stability of the molecular chain, alleviates the coating brittleness problem caused by excessive cross-linking, improves the coating's resistance to external impacts and temperature changes, and reduces the generation of microcracks. AB X The structural characteristics of monomer synthesis and the absence of cross-linking and branching growth during the reaction process result in a high retention of epoxy functional groups at the molecular ends. The three-dimensional spherical topology, low-segment regularity, and terminal group repulsion work together to minimize chain entanglement. The high functionality and minimal molecular entanglement of the spherical structure enable hyperbranched epoxy coatings to cure rapidly at low temperatures, producing a dense, strong, and highly resistant coating with excellent water and salt spray resistance. This enhances the coating's ability to resist the penetration of corrosive media, providing long-term protection for the substrate in harsh environments. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention. Example 1

[0015] Hyperbranched epoxy resin with improved protective performance of epoxy coatings is prepared by the following steps: (1) 347g of pentaerythritol tetraacrylate and 1008g of 1,4-pentadien-3-ol were added to the reactor. After argon gas protection, 10.9g of t-BuP2 catalyst was added. After reacting at 20°C for 2h, 360g of 0.5mol / L dilute hydrochloric acid was added to terminate the reaction. After the reaction was terminated, sodium hydroxide was added to neutralize the added dilute hydrochloric acid. Then water was added for washing. After washing, the organic phase and inorganic phase were separated. After drying the organic phase to remove residual water, hyperbranched polyester ether was obtained. (2) Mix 1000g of hyperbranched polyester ether, 8.5g each of initiators azobisisobutyronitrile and azobisisoheptanenitrile, 17g of chain growth control agent alpha-methylstyrene dimer, and 400g of xylene in a beaker and add them to the reactor. Mix 700g of allyl glycidyl ether and 210g of xylene evenly and place them in a constant pressure dropping funnel. Add them slowly to the reactor at 80℃ under nitrogen protection for 30 minutes. After the addition is complete, continue the reaction at 80℃ under nitrogen protection for 3 hours. After the reaction is complete, remove the solvent by distillation to obtain hyperbranched epoxy resin. Example 2

[0016] Hyperbranched epoxy resin with improved protective performance of epoxy coatings is prepared by the following steps: (1) 315g of pentaerythritol tetramethacrylate and 1008g of 1,4-pentadien-3-ol were added to the reactor. After argon gas protection, 10.6g of t-BuP2 catalyst was added. After reacting at 20°C for 2h, 350g of dilute hydrochloric acid with a concentration of 0.5mol / L was added to terminate the reaction. After the reaction was terminated, sodium hydroxide was added to neutralize the added dilute hydrochloric acid. Then water was added for washing. After washing, the organic phase and inorganic phase were separated. After drying the organic phase to remove residual water, hyperbranched polyester ether was obtained. (2) 1000g of hyperbranched polyester ether, 6.7g each of initiators azobisisobutyronitrile and azobisisoheptanenitrile, 16.6g of chain growth control agent alpha-methylstyrene dimer, and 400g of xylene were mixed in a beaker and then added to the reactor. 666g of allyl glycidyl ether and 200g of xylene were mixed evenly and placed in a constant pressure dropping funnel. The mixture was slowly added to the reactor at 80°C under nitrogen protection for 30 minutes. After the addition was completed, the reaction was continued at 80°C under nitrogen protection for 3 hours. After the reaction was completed, the solvent was removed by distillation to obtain hyperbranched epoxy resin. Example 3

[0017] Hyperbranched epoxy resin with improved protective performance of epoxy coatings is prepared by the following steps: (1) 325g of pentaerythritol tetramethacrylate and 1008g of 1,4-pentadien-3-ol were added to the reactor. After argon gas protection, 10.6g of t-BuP1 catalyst was added. After reacting at 20°C for 2h, 360g of 0.5mol / L dilute hydrochloric acid was added to terminate the reaction. After the reaction was terminated, sodium hydroxide was added to neutralize the added dilute hydrochloric acid. Then water was added for washing. After washing, the organic phase and inorganic phase were separated. After drying the organic phase to remove residual water, hyperbranched polyester ether was obtained. (2) Mix 1000g of hyperbranched polyester ether, 8.1g each of initiators azobisisobutyronitrile and azobisisoheptanenitrile, 16.2g of chain growth control agent alpha-methylstyrene dimer, and 500g of propylene glycol methyl ether in a beaker and add them to the reactor. Mix 625g of allyl glycidyl ether and 188g of propylene glycol methyl ether evenly and place them in a constant pressure dropping funnel. Slowly add them to the reactor at 80℃ under nitrogen protection for 30 minutes. After the addition is complete, continue the reaction at 80℃ under nitrogen protection for 3 hours. After the reaction is complete, remove the solvent by distillation to obtain hyperbranched epoxy resin. Example 4

[0018] Hyperbranched epoxy resin with improved protective performance of epoxy coatings is prepared by the following steps: (1) 336g of pentaerythritol tetraacrylate and 1008g of 1,4-pentadien-3-ol were added to the reactor. After argon gas protection, 10.8g of t-BuP2 catalyst was added. After reacting at 20°C for 2h, 360g of 0.5mol / L dilute hydrochloric acid was added to terminate the reaction. After the reaction was terminated, sodium hydroxide was added to neutralize the added dilute hydrochloric acid. Then water was added for washing. After washing, the organic phase and inorganic phase were separated. After drying the organic phase to remove residual water, hyperbranched polyester ether was obtained. (2) Mix 1000g of hyperbranched polyester ether, 8g each of initiators azobisisobutyronitrile and azobisisoheptanenitrile, 16.6g of chain growth control agent alpha-methylstyrene dimer, and 400g of propylene glycol methyl ether in a beaker and add them to the reactor. Mix 666g of allyl glycidyl ether with 200g of propylene glycol methyl ether and place it in a constant pressure dropping funnel. Add it slowly to the reactor at 90℃ under nitrogen protection for 30 minutes. After the addition is completed, continue the reaction at 90℃ under nitrogen protection for 3 hours. After the reaction is completed, remove the solvent by distillation to obtain hyperbranched epoxy resin. Comparative Example 1

[0019] The difference between Comparative Example 1 and Example 1 is that the allyl acrylate compound used in Comparative Example 1 is pentaerythritol triacrylate, while the rest is the same as in Example 1. Comparative Example 2

[0020] The difference between Comparative Example 2 and Example 1 is that the reaction temperature of pentaerythritol tetraacrylate and 1,4-pentadien-3-ol in Comparative Example 2 is 50°C, while the rest is the same as in Example 1.

[0021] The hyperbranched epoxy resins prepared in Examples 1 and 4 have the following molecular structural formulas: ; In the formula, the molecular structural formula of R is: .

[0022] The hyperbranched epoxy resins prepared in Examples 2 and 3 have the following molecular structural formulas: ; In the formula, the molecular structural formula of R is: .

[0023] The resins prepared in Examples 1-4 and Comparative Examples 1-2 were used as the main resins, and coatings were prepared according to the following weight ratio formulations and tested. The test results are shown in Table 1: Component A: 50 parts of main resin, 20 parts of titanium dioxide, 20 parts of xylene, and 10 parts of n-butanol; Component B: 50 parts of Tri-wood Polyamide 650 curing agent.

[0024] Component A and component B are used together at a mass ratio of 2:1.

[0025]

[0026] As can be seen from the test results table above, the hyperbranched epoxy resin prepared by this invention has good compatibility with conventional curing agents, and the prepared coating has excellent water resistance and salt spray resistance, high adhesion, good flexibility, and can provide long-term protection for the substrate.

[0027] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a hyperbranched epoxy resin with improved protective performance of epoxy coating, characterized in that: Includes the following steps: (1) Let the terminal allyl acrylate compound and 1,4-pentadien-3-ol react under argon protection, catalysis of phosphazene base catalyst and temperature of 10~40℃ for 1h~3h. Then add dilute hydrochloric acid to terminate the reaction. After the reaction is terminated, add sodium hydroxide to neutralize the added dilute hydrochloric acid. Then add water to wash. After washing, separate the organic phase and the inorganic phase. After drying the organic phase to remove residual water, the hyperbranched polyester ether is obtained. (2) Mix hyperbranched polyester ether, initiator, chain growth control agent and solvent, and slowly add allyl glycidyl ether and solvent mixture dropwise at 75℃~95℃ under nitrogen protection. After the addition is completed, continue the reaction at 75℃~95℃ under nitrogen protection for 2-4 hours. After the reaction is completed, remove the solvent to obtain hyperbranched epoxy resin.

2. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The terminal allyl acrylate compound is pentaerythritol tetraacrylate or pentaerythritol tetramethacrylate.

3. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The mass ratio of the terminal allyl acrylate compound to 1,4-pentadien-3-ol is 1:2.8-3.2; the amount of phosphazene base catalyst used is 0.5%-1.5% of the total mass of the terminal allyl acrylate compound and 1,4-pentadien-3-ol.

4. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The phosphazene alkaline catalyst is any one or a mixture of two or more of t-BuP1, t-BuP2 and t-BuP4 in any mass ratio.

5. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The initiator is one or a mixture of two of azobisisobutyronitrile and azobisisoheptanenitrile in any mass ratio.

6. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The chain growth control agent is alpha-methylstyrene dimer.

7. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The mass ratio of the terminal allyl glycidyl ether to the hyperbranched polyester ether is 1:1.4-1.6; the amount of the initiator is 0.2%-2% of the total mass of the allyl glycidyl ether and the hyperbranched polyester ether; and the amount of the chain growth control agent is 0.3%-1.2% of the total mass of the allyl glycidyl ether and the hyperbranched polyester ether.

8. The method for preparing the hyperbranched epoxy resin with improved protective performance of epoxy coating as described in claim 1, characterized in that: The solvent mentioned in step (2) is one or more of toluene, xylene, propylene glycol methyl ether, and butyl acetate in any mass ratio.

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