Preparation method of waterproof antifouling epoxy resin coating

Abstract

The invention relates to the technical field of coatings, and discloses a preparation method of a waterproof antifouling epoxy resin coating, which comprises the following steps: shearing and dispersing a solvent, 100 parts by weight of epoxy resin, 40-52 parts by weight of modified phenolic resin, 0.8-1 part by weight of a dispersant and 30-50 parts by weight of a filler to obtain the waterproof antifouling epoxy resin coating. The modified phenolic resin contains an imidazole structure, can promote the curing reaction of the epoxy resin and improve the molecular chain crosslinking degree of the epoxy resin, and meanwhile, the modified phenolic resin contains a flexible alkyl long chain and can play a very good toughening role, so that the epoxy resin has very high elongation at break while maintaining high tensile strength, and the service life of the epoxy resin is prolonged. Good toughness is shown. Moreover, the hydrophobicity of a paint film can be improved, the water absorption rate is reduced, and the water-resistant time is prolonged, so that the paint film has better antifouling, waterproof, salt-fog-resistant and corrosion-resistant properties.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and specifically to a preparation method of a waterproof and anti-fouling epoxy resin coating. Background Art

[0002] Epoxy resin coatings have good anti-corrosion performance and are widely used in aspects such as mud tanks, sewage tanks, and the inner walls of storage tanks of offshore oil production platforms. Phenolic resin has high heat resistance, good dimensional stability, high mechanical strength, and contains active phenolic hydroxyl groups, which can undergo ring-opening cross-linking reactions with the epoxy groups of epoxy resin, so it can be used as a curing agent for epoxy resin.

[0003] When using phenolic resin as the curing agent for epoxy resin, usually curing accelerators such as imidazole, 2, 4, 6-tris(dimethylaminomethyl)phenol, and 2-ethyl-4-methylimidazole need to be added to promote the curing cross-linking reaction of epoxy resin. The patent with the publication number CN106117964B discloses a modified boron phenolic resin and its preparation method and application. Using boron phenolic resin, silicate ester, titanate, etc. as raw materials, the prepared modified boron phenolic resin can be used as a curing agent for functional coatings and epoxy resin to improve the thermal stability and flame retardancy of the product, but this modified boron phenolic resin does not improve the water resistance, waterproofness, toughness and other properties of epoxy resin. Summary of the Invention

[0004] Technical problem to be solved: Provide a preparation method of an epoxy resin coating with high toughness and good waterproof performance.

[0005] Technical solution: A preparation method of a waterproof and anti-fouling epoxy resin coating: Step A: Add phenol, alkylimidazole phenol monomer, and aqueous formaldehyde solution to a reaction vessel equipped with a condensing reflux tube, heat up to 90 - 95 °C, dropwise add concentrated hydrochloric acid with a concentration of 8 - 12 mol / L, stir and react for 18 - 24 h, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0006] Step B: Add a solvent, 100 parts by weight of epoxy resin, 40 - 52 parts by weight of modified phenolic resin, 0.8 - 1.5 parts by weight of defoamer, 0.8 - 1 part by weight of dispersant, and 30 - 50 parts by weight of filler to a container, and shear and disperse to obtain a waterproof and anti-fouling epoxy resin coating.

[0007] Further, the ratio of alkylimidazole phenol monomer, phenol, formaldehyde, and concentrated hydrochloric acid in Step A is (0.2 - 0.4) mol : (0.6 - 0.8) mol : (1.05 - 1.1) mol : (0.9 - 1.2) mL.

[0008] Further, the solvent in Step B is ethyl acetate, butyl acetate, or n-butanol.

[0009] Furthermore, the filler is any one or a combination of titanium dioxide, mica powder, and talc powder.

[0010] Furthermore, the preparation method of the alkylimidazole phenol monomer is as follows: Step (1): Add tetrahydrofuran, 4-imidazole formaldehyde, 1-chloroalkane, and sodium hydroxide in a molar ratio of 1 mol:(0.8 - 1) mol:(1 - 1.1) mol to a reaction vessel equipped with a condenser reflux tube. Heat the mixture to 50 - 60 °C, stir and react for 12 - 18 h, then perform vacuum distillation, water washing, and drying to obtain alkylimidazole formaldehyde. The reaction formula is as follows: .

[0011] Step (2): Add ethanol, alkylimidazole formaldehyde, and 4-aminophenol in a molar ratio of (1 - 1.1) mol:1 mol to the reaction vessel. Heat the mixture to 35 - 50 °C, stir and react for 6 - 12 h, then perform vacuum distillation, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain the alkylimidazole phenol monomer. The reaction formula is as follows: .

[0012] Furthermore, the structural formula of the 1-chloroalkane is Cl - C n H 2n+1 , where n is 10 - 18.

[0013] Technical effect: In the present invention, the alkylimidazole phenol monomer is used as a functional monomer, which undergoes a polycondensation reaction with phenol and formaldehyde to obtain a modified phenolic resin. Using this as a curing agent and compounding it with fillers such as epoxy resin, defoamer, and talc powder, a waterproof and antifouling epoxy resin coating is obtained. The modified phenolic resin contains an imidazole structure, which can promote the curing reaction of the epoxy resin and increase the crosslinking degree of the molecular chain of the epoxy resin. At the same time, the modified phenolic resin contains a flexible alkyl long chain, which can play a good toughening role, enabling the epoxy resin to have a high elongation at break while maintaining a high tensile strength, showing good toughness.

[0014] The modified phenolic resin of the present invention contains an alkyl long chain, has stronger hydrophobicity. When introduced into the epoxy resin matrix, it can improve the hydrophobicity of the paint film, reduce the water absorption rate, increase the water resistance time, and endow the paint film of the coating with better antifouling, waterproof, water resistance, and salt spray corrosion resistance. Specific embodiments

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0016] The epoxy resin of the present invention, model E44, is from Wuxi Jiunai Anticorrosive Material Co., Ltd. The dispersant, model TF-800, is from Beijing Qifei Technology Development Co., Ltd. The defoamer, model KS-508, is from Guangzhou Situyuan Chemical Industry Co., Ltd.

[0017] Example 1: Step (1): Add 80 mL of tetrahydrofuran, 30 mmol of 4-imidazolecarboxaldehyde, 30 mmol of 1-chlorodecane, and 33 mmol of sodium hydroxide into a reaction vessel equipped with a condensing reflux tube. Heat up to 50 °C and stir for 18 h. Then perform vacuum distillation, wash with water, and dry to obtain alkylimidazolecarboxaldehyde.

[0018] Step (2): Add 150 mL of ethanol, 33 mmol of alkylimidazolecarboxaldehyde, and 30 mmol of 4-aminophenol into the reaction vessel. Heat up to 40 °C and stir for 12 h. Then perform vacuum distillation, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain alkylimidazolephenol monomer.

[0019] Step (3): Add 70 mmol of phenol, 30 mmol of alkylimidazolephenol monomer, and an aqueous solution containing 110 mmol of formaldehyde into a reaction vessel equipped with a condensing reflux tube. Heat up to 90 °C, dropwise add 0.09 mL of concentrated hydrochloric acid with a concentration of 12 mol / L, stir for 24 h, cool down, filter, wash with water and ethanol, and dry to obtain modified phenolic resin.

[0020] Step (4): Add 120 mL of butyl acetate, 100 g of epoxy resin E44, 40 g of modified phenolic resin, 1.5 g of defoamer, 1 g of dispersant, and 42 g of talc powder into the container, and perform shear dispersion to obtain a waterproof and antifouling epoxy resin coating.

[0021] Example 2: Step (1): Add 100 mL of tetrahydrofuran, 30 mmol of 4-imidazolecarboxaldehyde, 24 mmol of 1-chlorooctadecane, and 33 mmol of sodium hydroxide into a reaction vessel equipped with a condensing reflux tube. Heat up to 60 °C and stir for 12 h. Then perform vacuum distillation, wash with water, and dry to obtain alkylimidazolecarboxaldehyde.

[0022] Step (2): Add 120 mL of ethanol, 30 mmol of alkylimidazolecarboxaldehyde, and 30 mmol of 4-aminophenol into the reaction vessel. Heat up to 35 °C and stir for 12 h. Then perform vacuum distillation, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain alkylimidazolephenol monomer.

[0023] Step (3): Add 80 mmol of phenol, 20 mmol of alkylimidazole phenol monomer, and an aqueous solution containing 105 mmol of formaldehyde into a reaction vessel equipped with a condensing reflux pipe. Heat the mixture to 90 °C, add dropwise 0.09 mL of concentrated hydrochloric acid with a concentration of 12 mol / L, stir and react for 24 h, cool, filter, wash with water and ethanol, and dry to obtain the modified phenolic resin.

[0024] Step (4): Add 150 mL of n-butanol, 100 g of epoxy resin E44, 44 g of modified phenolic resin, 0.8 g of defoamer, 0.8 g of dispersant, and 30 g of titanium dioxide into a container, and perform shear dispersion to obtain a waterproof and antifouling epoxy resin coating.

[0025] Example 3: Step (1): Add 80 mL of tetrahydrofuran, 30 mmol of 4-imidazole formaldehyde, 24 mmol of 1-chlorotetradecane, and 30 mmol of sodium hydroxide into a reaction vessel equipped with a condensing reflux pipe. Heat the mixture to 55 °C, stir and react for 18 h, perform vacuum distillation, wash with water, and dry to obtain alkylimidazole formaldehyde.

[0026] Step (2): Add 150 mL of ethanol, 33 mmol of alkylimidazole formaldehyde, and 30 mmol of 4-aminophenol into a reaction vessel. Heat the mixture to 50 °C, stir and react for 6 h, perform vacuum distillation, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain alkylimidazole phenol monomer.

[0027] Step (3): Add 60 mmol of phenol, 40 mmol of alkylimidazole phenol monomer, and an aqueous solution containing 110 mmol of formaldehyde into a reaction vessel equipped with a condensing reflux pipe. Heat the mixture to 95 °C, add dropwise 0.12 mL of concentrated hydrochloric acid with a concentration of 8 mol / L, stir and react for 18 h, cool, filter, wash with water and ethanol, and dry to obtain the modified phenolic resin.

[0028] Step (4): Add 150 mL of ethyl acetate, 100 g of epoxy resin E44, 48 g of modified phenolic resin, 1.2 g of defoamer, 1 g of dispersant, and 50 g of mica powder into a container, and perform shear dispersion to obtain a waterproof and antifouling epoxy resin coating.

[0029] Example 4: Step (1): Add 120 mL of butyl acetate, 100 g of epoxy resin E44, 52 g of modified phenolic resin (prepared in Example 1), 1.5 g of defoamer, 1 g of dispersant, and 42 g of talc powder into a container, and perform shear dispersion to obtain a waterproof and antifouling epoxy resin coating.

[0030] Comparative Example 1: Step (1): Add 100 mmol of phenol and an aqueous solution containing 110 mmol of formaldehyde into a reaction vessel equipped with a condensing reflux pipe. Heat the mixture to 90 °C, dropwise add 0.09 mL of concentrated hydrochloric acid with a concentration of 12 mol / L, stir and react for 24 h, cool, filter, wash with water and ethanol, and dry to obtain phenolic resin.

[0031] Step (2): Add 120 mL of butyl acetate, 100 g of epoxy resin E44, 40 g of phenolic resin, 1.5 g of defoamer, 1 g of dispersant, and 42 g of talc powder into a container, shear and disperse to obtain an epoxy resin coating.

[0032] Comparative Example 2: Step (1): Add 80 mL of tetrahydrofuran, 30 mmol of 4-imidazole formaldehyde, 30 mmol of 1-chloroethane, and 33 mmol of sodium hydroxide into a reaction vessel equipped with a condensing reflux pipe. Heat the mixture to 50 °C, stir and react for 18 h, carry out reduced pressure distillation, wash with water, and dry to obtain ethylimidazole formaldehyde. The structural formula is 。

[0033] Step (2): Add 150 mL of ethanol, 33 mmol of alkylimidazole formaldehyde, and 30 mmol of 4-aminophenol into the reaction vessel. Heat the mixture to 40 °C, stir and react for 12 h, carry out reduced pressure distillation, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain ethylimidazole phenol monomer. The structural formula is 。

[0034] Step (3): Add 70 mmol of phenol, 30 mmol of ethylimidazole phenol monomer, and an aqueous solution containing 110 mmol of formaldehyde into a reaction vessel equipped with a condensing reflux pipe. Heat the mixture to 90 °C, dropwise add 0.09 mL of concentrated hydrochloric acid with a concentration of 12 mol / L, stir and react for 24 h, cool, filter, wash with water and ethanol, and dry to obtain modified phenolic resin.

[0035] Step (4): Add 120 mL of butyl acetate, 100 g of epoxy resin E44, 40 g of modified phenolic resin, 1.5 g of defoamer, 1 g of dispersant, and 42 g of talc powder into a container, shear and disperse to obtain an epoxy resin coating.

[0036] Comparative Example 3: Step (1): Add 150 mL of ethanol, 33 mmol of decanal (CAS No. 112-31-2), and 30 mmol of 4-aminophenol into a reaction vessel. Heat the mixture to 40 °C, stir and react for 12 h, carry out reduced pressure distillation, wash with petroleum ether, and dry to obtain alkylphenol monomer. The structural formula is 。

[0037] Step (2), add 70mmol of alkylphenol monomer, 30mmol of alkylimidazolephenol monomer and an aqueous solution containing 110mmol of formaldehyde into a reaction vessel provided with a condenser reflux tube, heat to 90°C, dropwise add 0.09mL of 12mol / L concentrated hydrochloric acid, stir to react for 24h, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0038] Step (3), add 120 mL of butyl acetate, 100 g of epoxy resin E44, 40 g of modified phenolic resin, 1.5 g of defoamer, 1 g of dispersant, and 42 g of talcum powder into a container, shear and disperse, and obtain an epoxy resin coating.

[0039] The curing conditions of epoxy resin coating are first cured at 100℃ for 2h and then cured at 150℃ for 3h. The salt spray resistance of the paint film is tested according to GB / T1771-2007. The substrate is tinplate. The flexibility of the paint film is tested according to GB / T 1731-2020. The water resistance is tested according to GB / T 1733-1993.

[0040] The paint film was dried and weighed (m0), then immersed in water at room temperature for 120 hours, the paint film was taken out, the surface moisture was wiped off, and the weight was weighed (m), and the water absorption rate W was calculated. W = (m-m0) / m0×100%.

[0041] The epoxy resin coating was cast into the mold, first cured at 100°C for 3h, and then cured at 150°C for 4h. The tensile properties were tested according to GB / T2567-2021 method.

[0042] Table 1

[0043] Table 2

[0044] As shown in Table 1, in Comparative Example 1, phenolic resin is used as the curing agent of the epoxy resin coating. The coating has low salt spray resistance and water resistance, low water absorption, poor anti-corrosion and waterproof properties, low tensile strength and elongation at break, and poor flexibility.

[0045] The modified phenolic resin of Examples 1-4 contains an imidazole structure, which can promote the curing reaction of epoxy resin and improve the molecular chain crosslinking degree of epoxy resin. At the same time, the modified phenolic resin contains a flexible alkyl long chain, which can play a good toughening role, so that the epoxy resin has a high elongation at break while maintaining a high tensile strength, showing good toughness. In addition, the phenolic resin containing an alkyl long chain has stronger hydrophobicity, and when introduced into the epoxy resin matrix, the hydrophobicity of the paint film can be improved, the water absorption rate can be reduced, and the water resistance time can be increased, so that the paint film has better waterproof and water resistance and salt spray corrosion resistance.

[0046] The modified phenolic resin of Comparative Example 2 contains imidazole groups, which can promote the curing reaction of epoxy resin, increase the crosslinking degree of the molecular chain of epoxy resin, and is beneficial to improving the tensile strength of the paint film. However, the toughening effect is poor, and the elongation at break and flexibility of the paint film of the coating are poor. In addition, the water absorption rate is high and the water resistance time is low, and the water resistance and waterproof performance of the paint film are not good.

[0047] The modified phenolic resin of Comparative Example 3 contains long alkyl chains, and has a very good toughening effect, improving the elongation at break and flexibility of the coating, and increasing the water resistance time and reducing the water absorption rate, thus improving the water resistance and waterproof performance of the paint film. However, the tensile strength of the coating is low.

Claims

1. A method for preparing a waterproof and antifouling epoxy resin coating, characterized in that: The preparation method is as follows: Step A, add phenol and the structural formula alkyl imidazole phenol monomer, formaldehyde aqueous solution, after heating, concentrated hydrochloric acid is added dropwise, after reaction, cooling, filtering, washing with water and ethanol, and drying to obtain a modified phenolic resin; wherein n in the structural formula of the alkyl imidazole phenol monomer is 10-18; Step B, adding a solvent, 100 parts by weight of epoxy resin, 40-52 parts by weight of modified phenolic resin, 0.8-1.5 parts by weight of defoamer, 0.8-1 parts by weight of dispersant, and 30-50 parts by weight of filler into a container, shearing and dispersing, to obtain a waterproof and antifouling epoxy resin coating.

2. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 1, characterized in that: In the step A, the ratio of the alkyl imidazole phenol monomer, phenol, formaldehyde and concentrated hydrochloric acid is (0.2-0.4) mol: (0.6-0.8) mol: (1.05-1.1) mol: (0.9-1.2) mL.

3. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 1, characterized in that: The molar concentration of concentrated hydrochloric acid in step A is 8-12 mol / L.

4. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 1, characterized in that: The reaction temperature in step A is 90-95° C. and the reaction time is 18-24 hours.

5. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 1, characterized in that: The solvent in step B is ethyl acetate, butyl acetate or n-butanol.

6. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 1, characterized in that: The filler is any one or a combination of titanium dioxide, mica powder and talcum powder.

7. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 2, characterized in that: The preparation method of the alkyl imidazole phenol monomer is: Step (1), adding tetrahydrofuran, 4-imidazole carboxaldehyde, 1-chloroalkane and sodium hydroxide into a reaction vessel, heating to 50-60° C., stirring for reaction for 12-18 hours, distilling under reduced pressure, washing with water and drying to obtain alkylimidazole carboxaldehyde; Step (2), add ethanol, alkyl imidazole formaldehyde and 4-aminophenol into a reaction container, raise the temperature to 35-50° C., stir and react for 6-12 hours, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain an alkyl imidazole phenol monomer.

8. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 7, characterized in that: In the step (1), the ratio of 4-imidazolecarboxaldehyde, 1-chloroalkane and sodium hydroxide is 1 mol: (0.8-1) mol: (1-1.1) mol.

9. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 8, characterized in that: The structural formula of the 1-chloroalkane is Cl-C n H 2n+1 , n is 10-18.

10. The method for preparing the waterproof and antifouling epoxy resin coating according to claim 9, characterized in that: In the step (2), the ratio of alkyl imidazole carboxaldehyde to 4-aminophenol is (1-1.1) mol:1 mol.

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