Preparation method of waterproof and antifouling epoxy resin coating

Abstract

The present invention relates to the field of coating technology, and discloses a preparation method of a waterproof and antifouling epoxy resin coating, by solvent, 100 parts by weight of epoxy resin, 40 52 parts by weight of modified phenolic resin, 0.8 1 parts by weight of dispersant, 30 50 parts by weight of filler, shear dispersion, obtain waterproof and antifouling epoxy resin coating. The modified phenolic resin of the present invention contains imidazole structure, can promote the curing reaction of epoxy resin, improve the molecular chain crosslinking degree of epoxy resin, while the modified phenolic resin contains flexible alkyl long chain, can play a good toughening effect, make epoxy resin when maintaining high tensile strength, also have very high elongation at break, show good toughness. And can improve the hydrophobicity of coating film, reduce water absorption, improve water-resistant time, make coating film have better antifouling, waterproof water resistance and salt spray corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a method for preparing a waterproof and antifouling epoxy resin coating. Background Art

[0002] Epoxy resin coatings have excellent corrosion resistance and are widely used in mud tanks, sewage tanks, and storage tank linings on offshore oil platforms. Phenolic resins offer high heat resistance, excellent dimensional stability, and high mechanical strength. They also contain reactive phenolic hydroxyl groups that react with the epoxy groups of epoxy resins through a ring-opening crosslinking reaction, making them suitable as curing agents for epoxy resins.

[0003] When using phenolic resin as an epoxy resin curing agent, it is usually necessary to add a curing accelerator such as imidazole, 2,4,6-tris(dimethylaminomethyl)phenol, or 2-ethyl-4-methylimidazole to promote the curing and crosslinking reaction of the epoxy resin. Patent publication number CN106117964B discloses a modified boron phenolic resin and its preparation method and application. The modified boron phenolic resin prepared using boron phenolic resin, silicate, titanate, etc. as raw materials can be used as a curing agent for functional coatings and epoxy resins, improving the thermal stability and flame retardancy of the products. However, the modified boron phenolic resin does not improve the water resistance, waterproofness, toughness, and other properties of the epoxy resin. Summary of the Invention

[0004] Technical problem to be solved: Provides a method for preparing an epoxy resin coating with high toughness and good waterproof performance.

[0005] Technical solution: A method for preparing a waterproof and antifouling epoxy resin coating:

[0006] Step A: Add phenol, alkylimidazole phenol monomer, and formaldehyde aqueous solution to a reaction vessel equipped with a condenser reflux tube, heat to 90-95° C., dropwise add concentrated hydrochloric acid with a concentration of 8-12 mol / L, stir and react for 18-24 hours, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0007] 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.

[0008] Furthermore, in step A, the ratio of 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.

[0009] Furthermore, the solvent in step B is ethyl acetate, butyl acetate or n-butanol.

[0010] Furthermore, the filler is any one or a combination of titanium dioxide, mica powder, and talc powder.

[0011] Furthermore, the preparation method of the alkyl imidazole phenol monomer is:

[0012] Step (1) adds tetrahydrofuran, 4-imidazolecarboxaldehyde, 1-chloroalkane, and sodium hydroxide in a ratio of 1 mol: (0.8-1) mol: (1-1.1) mol to a reaction vessel equipped with a condenser reflux tube, raises the temperature to 50-60°C, stirs and reacts for 12-18 hours, distills under reduced pressure, washes with water, and dries to obtain alkylimidazolecarboxaldehyde. The reaction formula is as follows:

[0013] .

[0014] Step (2): Add ethanol, alkylimidazole formaldehyde in a ratio of (1-1.1) mol:1 mol, and 4-aminophenol to a reaction vessel, 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 alkylimidazole phenol monomer. The reaction formula is as follows:

[0015] .

[0016] Furthermore, the structural formula of 1-chloroalkane is Cl-C n H 2n+1 , n is 10-18.

[0017] Technical Effect: The present invention uses an alkyl imidazole phenol monomer as a functional monomer to undergo a polycondensation reaction with phenol and formaldehyde to obtain a modified phenolic resin. This modified phenolic resin is used as a curing agent and compounded with epoxy resin, a defoaming agent, talc and other fillers to obtain a waterproof and antifouling epoxy resin coating. The modified phenolic resin contains an imidazole structure, which can promote the curing reaction of the epoxy resin and increase the cross-linking degree of the epoxy resin's molecular chain. At the same time, the modified phenolic resin contains flexible long alkyl chains, which can play a good toughening role, allowing the epoxy resin to have a high elongation at break while maintaining high tensile strength, showing excellent toughness.

[0018] The modified phenolic resin of the present invention contains long alkyl chains and has stronger hydrophobicity. When introduced into the epoxy resin matrix, it can improve the hydrophobicity of the paint film, reduce the water absorption rate, and increase the water resistance time, so that the paint film has better anti-fouling, water resistance and salt spray resistance. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be described clearly and completely below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0020] The epoxy resin of the present invention, model E44, is from Wuxi Jiunai Anticorrosion Materials 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 Co., Ltd.

[0021] Example 1:

[0022] Step (1): add 80 mL of tetrahydrofuran, 30 mmol of 4-imidazolecarboxaldehyde, 30 mmol of 1-chlorodecane, and 33 mmol of sodium hydroxide to a reaction vessel equipped with a condenser reflux tube, heat to 50° C., stir and react for 18 h, distill under reduced pressure, wash with water, and dry to obtain alkylimidazolecarboxaldehyde.

[0023] Step (2): add 150 mL of ethanol, 33 mmol of alkyl imidazole formaldehyde, and 30 mmol of 4-aminophenol to a reaction vessel, raise the temperature to 40° C., stir and react for 12 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain an alkyl imidazole phenol monomer.

[0024] Step (3), add 70mmol of phenol, 30mmol of alkylimidazole phenol monomer, and an aqueous solution containing 110mmol of formaldehyde to a reaction vessel equipped with a condenser reflux tube, heat to 90°C, dropwise add 0.09mL of 12mol / L concentrated hydrochloric acid, stir and react for 24h, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0025] 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 into a container, and shear and disperse to obtain a waterproof and antifouling epoxy resin coating.

[0026] Example 2:

[0027] Step (1): add 100 mL of tetrahydrofuran, 30 mmol of 4-imidazolecarboxaldehyde, 24 mmol of 1-chlorooctadecane, and 33 mmol of sodium hydroxide to a reaction vessel equipped with a condenser reflux tube, heat to 60° C., stir and react for 12 h, distill under reduced pressure, wash with water, and dry to obtain alkylimidazolecarboxaldehyde.

[0028] Step (2): add 120 mL of ethanol, 30 mmol of alkylimidazole formaldehyde, and 30 mmol of 4-aminophenol to a reaction vessel, raise the temperature to 35° C., stir and react for 12 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain an alkylimidazole phenol monomer.

[0029] Step (3): add 80 mmol of phenol, 20 mmol of alkyl imidazole phenol monomer, and an aqueous solution containing 105 mmol of formaldehyde to a reaction vessel equipped with a condenser reflux tube, heat to 90° C., dropwise add 0.09 mL of 12 mol / L concentrated hydrochloric acid, stir and react for 24 hours, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0030] Step (4): add 150 mL of n-butanol, 100 g of epoxy resin E44, 44 g of modified phenolic resin, 0.8 g of defoaming agent, 0.8 g of dispersant, and 30 g of titanium dioxide into a container, and shear and disperse to obtain a waterproof and antifouling epoxy resin coating.

[0031] Example 3:

[0032] Step (1): add 80 mL of tetrahydrofuran, 30 mmol of 4-imidazolecarboxaldehyde, 24 mmol of 1-chlorotetradecane, and 30 mmol of sodium hydroxide to a reaction vessel equipped with a condenser reflux tube, heat to 55° C., stir and react for 18 h, distill under reduced pressure, wash with water, and dry to obtain alkylimidazolecarboxaldehyde.

[0033] Step (2): add 150 mL of ethanol, 33 mmol of alkyl imidazole formaldehyde, and 30 mmol of 4-aminophenol to a reaction vessel, heat to 50° C., stir and react for 6 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain an alkyl imidazole phenol monomer.

[0034] Step (3): add 60 mmol of phenol, 40 mmol of alkyl imidazole phenol monomer, and an aqueous solution containing 110 mmol of formaldehyde to a reaction vessel equipped with a condenser reflux tube, heat to 95° C., dropwise add 0.12 mL of 8 mol / L concentrated hydrochloric acid, stir and react for 18 h, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0035] Step (4): add 150 mL of ethyl acetate, 100 g of epoxy resin E44, 48 g of modified phenolic resin, 1.2 g of defoaming agent, 1 g of dispersant, and 50 g of mica powder into a container, shear and disperse, and obtain a waterproof and antifouling epoxy resin coating.

[0036] Example 4:

[0037] 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 into a container, and shear and disperse to obtain a waterproof and antifouling epoxy resin coating.

[0038] Comparative Example 1:

[0039] Step (1): add 100 mmol of phenol and an aqueous solution containing 110 mmol of formaldehyde to a reaction vessel equipped with a condenser reflux tube, heat to 90° C., dropwise add 0.09 mL of 12 mol / L concentrated hydrochloric acid, stir and react for 24 hours, cool, filter, wash with water and ethanol, and dry to obtain a phenolic resin.

[0040] 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 into a container, and shear and disperse to obtain an epoxy resin coating.

[0041] Comparative Example 2:

[0042] Step (1) Add 80mL of tetrahydrofuran, 30mmol of 4-imidazolecarboxaldehyde, 30mmol of 1-chloroethane, and 33mmol of sodium hydroxide to a reaction vessel equipped with a condenser reflux tube, heat to 50°C, stir and react for 18h, distill under reduced pressure, wash with water, and dry to obtain ethylimidazolecarboxaldehyde. The structural formula is .

[0043] Step (2): Add 150 mL of ethanol, 33 mmol of alkyl imidazole formaldehyde, and 30 mmol of 4-aminophenol to the reaction vessel, heat to 40°C, stir and react for 12 hours, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain ethyl imidazole phenol monomer. The structural formula is .

[0044] Step (3), add 70mmol of phenol, 30mmol of ethylimidazole phenol monomer, and an aqueous solution containing 110mmol of formaldehyde to a reaction vessel equipped with a condenser reflux tube, heat to 90°C, dropwise add 0.09mL of 12mol / L concentrated hydrochloric acid, stir and react for 24h, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0045] 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 into a container, shear and disperse, and obtain an epoxy resin coating.

[0046] Comparative Example 3:

[0047] Step (1) Add 150 mL of ethanol, 33 mmol of decanal (CAS No. 112-31-2), and 30 mmol of 4-aminophenol to the reaction vessel, heat to 40°C, stir and react for 12 hours, distill under reduced pressure, wash with petroleum ether, and dry to obtain an alkylphenol monomer. The structural formula is .

[0048] Step (2): add 70 mmol of alkylphenol monomer, 30 mmol of alkylimidazolephenol monomer, and an aqueous solution containing 110 mmol of formaldehyde to a reaction vessel equipped with a condenser reflux tube, heat to 90° C., dropwise add 0.09 mL of 12 mol / L concentrated hydrochloric acid, stir and react for 24 hours, cool, filter, wash with water and ethanol, and dry to obtain a modified phenolic resin.

[0049] 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 talc into a container, and shear and disperse to obtain an epoxy resin coating.

[0050] The epoxy resin coating was cured at 100°C for 2 hours, followed by 150°C for 3 hours. The salt spray resistance of the paint film was tested according to GB / T 1771-2007. The substrate was tinplate. The flexibility of the paint film was tested according to GB / T 1731-2020. Water resistance was tested according to GB / T 1733-1993.

[0051] The paint film was dried and weighed (m0), then immersed in water at room temperature for 120 hours. The paint film was removed, the surface moisture was wiped off, and the film was weighed (m). The water absorption W was calculated as W = (m-m0) / m0×100%.

[0052] The epoxy resin coating was cast into the mold and cured at 100°C for 3 hours and then at 150°C for 4 hours. The tensile properties were tested according to GB / T2567-2021.

[0053] Table 1

[0054]

[0055] Table 2

[0056]

[0057] As shown in Table 1, Comparative Example 1 uses phenolic resin as the curing agent for the epoxy resin coating. The coating has low salt spray resistance and water resistance, low water absorption, poor corrosion and waterproof performance, low tensile strength and elongation at break, and poor flexibility.

[0058] The modified phenolic resins of Examples 1-4 contain an imidazole structure, which can promote the curing reaction of the epoxy resin and increase the molecular chain crosslinking degree of the epoxy resin. Furthermore, the modified phenolic resins contain flexible long alkyl chains, which can effectively enhance toughness, allowing the epoxy resin to have a high elongation at break while maintaining high tensile strength, demonstrating excellent toughness. Furthermore, the phenolic resins containing long alkyl chains have stronger hydrophobicity. When introduced into the epoxy resin matrix, they can improve the hydrophobicity of the paint film, reduce water absorption, and increase water resistance, resulting in a paint film with improved water resistance, salt spray resistance, and corrosion resistance.

[0059] The modified phenolic resin of Comparative Example 2 contains imidazole groups, which can promote the curing reaction of the epoxy resin and increase the molecular chain crosslinking degree of the epoxy resin, which is beneficial for 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 are poor. In addition, the water absorption rate is high, the water resistance time is short, and the water resistance and waterproofing properties of the paint film are poor.

[0060] The modified phenolic resin of Comparative Example 3 contains long alkyl chains, which has a good toughening effect, improves the elongation at break and flexibility of the coating, increases the water resistance time, reduces the water absorption rate, and improves the water resistance and waterproof performance of the paint film, but 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 to the reaction vessel. 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, wherein: In step A, the ratio of alkylimidazole 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, wherein: 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, wherein: 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, wherein: 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 talc 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 to a reaction vessel, heating to 50-60° C., stirring and reacting for 12-18 hours, distilling under reduced pressure, washing with water, and drying to obtain alkylimidazole carboxaldehyde; Step (2): add ethanol, alkylimidazole formaldehyde and 4-aminophenol to a reaction vessel, 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 alkylimidazole 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 alkylimidazole formaldehyde to 4-aminophenol is (1-1.1) mol:1 mol.

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