Modified epoxy resins and methods for their preparation

Abstract

The present disclosure provides a modified epoxy resin and a preparation method thereof. The raw materials of the modified epoxy resin include an epoxy resin, a curing agent amine compound, a low-molecular monooxy compound and a polyurea polymer. The preparation method of the modified epoxy resin comprises the following steps: reacting a bifunctional amine compound with a bifunctional isocyanate compound in an organic solvent to obtain a polyurea polymer; adding a low-molecular monooxy compound into an epoxy resin and stirring, then adding a curing agent amine compound and the polyurea polymer and stirring, coating on a surface of a substrate after removing bubbles in the system under vacuum negative pressure, to obtain a modified epoxy resin coating.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of coatings, in particular to the field of material modification, and more particularly to modified epoxy resin and a method for preparing the same. BACKGROUND

[0002] Chemical, electrochemical reactions and physical dissolution of metal materials in marine environment will greatly shorten the service life of marine engineering equipment. At present, in order to solve the corrosion problem of marine engineering equipment, researchers have proposed a number of targeted solutions, among which anticorrosion coating is the most effective and commonly used protection strategy.

[0003] Epoxy-based anticorrosion coating is favored by researchers due to its high adhesion, low shrinkage and excellent resistance to chemical solvents. However, due to the benzene ring structure rich in epoxy resin, the high adhesion of epoxy resin also leads to excessive rigidity; in actual application, microcracks are easily produced under external force impact, leading to pitting corrosion on the surface of steel, greatly reducing the service life of anticorrosion coating and seriously endangering the safe operation of marine engineering equipment.

[0004] At present, the repair work of damaged coating material is mostly carried out by manual method, which is time-consuming and laborious. Therefore, it is urgent for researchers to develop an anticorrosion coating with long service life, excellent corrosion resistance and self-repairing function. SUMMARY

[0005] In order to solve the problems in the background art, the present disclosure provides a modified epoxy resin and a method for preparing the same. The raw materials of the modified epoxy resin include epoxy resin and curing agent amine compound, and also include low molecular monooxy compound and polyurea polymer.

[0006] In some embodiments, the low molecular monooxy compound includes at least one of n-butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether and 5-ethylhexyl glycidyl ether.

[0007] In some embodiments, the polyurea polymer includes a compound prepared by reacting a bifunctional amine compound with a bifunctional isocyanate compound in an organic solvent.

[0008] In some embodiments, the bifunctional amine compound includes at least one of polyamide, polyether amine, isophorone diamine and diethylene triamine.

[0009] In some embodiments, the bifunctional isocyanate compound includes at least one of isophorone diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate and hexamethylene diisocyanate.

[0010] The preparation method of the modified epoxy resin comprises the following steps: S1: reacting a bifunctional amine compound with a bifunctional isocyanate compound in an organic solvent to obtain a polyurea polymer; S2: adding a low-molecular monooxy compound to an epoxy resin and stirring, then adding a curing agent amine compound and the polyurea polymer and stirring, coating on a substrate surface after removing bubbles in the system under vacuum negative pressure to obtain a modified epoxy resin coating.

[0011] In some embodiments, the reaction temperature of step S1 is 10-120 DEG C, and the reaction time is 2-24 h.

[0012] In some embodiments, in step S1, the molar ratio of the bifunctional amine compound to the bifunctional isocyanate compound is (1-10):(0.1-10).

[0013] In some embodiments, in step S2, the mass ratio of the epoxy resin, the low-molecular monooxy compound, the polyurea polymer and the curing agent amine compound is (0.1-30):(0.1-30):(0.01-10):(0.01-10).

[0014] In some embodiments, step S1 is: dissolving a bifunctional amine compound in an organic solvent to form an organic solution, introducing nitrogen to remove air in the device, and then placing in an ice water bath; adding a bifunctional isocyanate compound to the organic solution under constant pressure to obtain a polyurea polymer.

[0015] The epoxy resin composite provided by the present disclosure can increase the impact resistance of the coating and provide self-repairing function for the coating, greatly prolonging the service life of the corrosion-resistant coating. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The infrared spectrum of each epoxy coating in Examples 1-7.

[0017] Figure 2 The adhesion of each epoxy coating in Examples 1-7.

[0018] Figure 3 The impact resistance of each epoxy coating in Examples 1-7.

[0019] Figure 4 The open circuit potential of each epoxy coating in Examples 1-7.

[0020] Figure 5 The impedance at 0.01 Hz of each epoxy coating in Examples 1-7. DETAILED DESCRIPTION

[0021] It should be understood that the disclosed embodiments are only examples of the disclosure and the disclosure can be implemented in various forms, therefore, the specific details of the disclosure should not be interpreted as limiting, but only as a basis for teaching those skilled in the art to implement the disclosure in various ways. In the description of the disclosure, the terms not explicitly stated and professional terms are common knowledge of those skilled in the art, and the methods not explicitly stated are conventional methods known to those skilled in the art.

[0022] The endpoints of the ranges and any values disclosed in the present disclosure are not limited to the precise values stated. The ranges or values should be construed to be roughly about the ranges or values disclosed, and the endpoints between ranges of values, the endpoints of ranges of values and individual values between ranges of values, and individual values can be combined with each other to form one or more new ranges of values, which should be considered to be specifically disclosed herein.

[0023] [Modified epoxy resin]

[0024] The modified epoxy resin provided by the disclosure reduces the crosslinking density of the epoxy coating by adding a low molecular monooxy compound to achieve self-repairing performance; and adds a polyurea polymer to increase the soft segment and improve the toughness of the epoxy coating; and the polyurea polymer is rich in hydrogen bonds, and the supramolecular force is also helpful to improve the self-repairing performance of the epoxy coating.

[0025] The modified epoxy resin provided by the disclosure, which raw materials include epoxy resin and curing agent amine compound, is characterized in that it further includes a low molecular monooxy compound and a polyurea polymer.

[0026] In some embodiments, the epoxy resin includes at least one of E51, E44, E20, and E12. In some embodiments, the curing agent amine compound includes at least one of polyamide, polyether amine, isophorone diamine, and diethylene triamine.

[0027] In some embodiments, the low molecular monooxy compound includes at least one of n-butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, and 5-ethylhexyl glycidyl ether.

[0028] In some embodiments, the mass ratio of the epoxy resin to the low molecular monooxy compound is (1-20):(0.1-10).

[0029] In some embodiments, the polyurea polymer comprises a compound prepared by reacting a bifunctional amine compound with a bifunctional isocyanate compound in an organic solvent. In some embodiments, the bifunctional amine compound comprises at least one of a polyamide, a polyetheramine, isophorone diamine, diethylenetriamine. In some embodiments, the bifunctional isocyanate compound comprises at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate. In some embodiments, the molar ratio of the bifunctional amine compound to the bifunctional isocyanate compound is (1-10):(0.1-10). In some embodiments, the mass ratio of the epoxy resin, the low molecular monooxy compound, the polyurea polymer, and the curing agent amine compound is (0.1-30):(0.1-30):(0.01-10):(0.01-10).

[0030] In some embodiments, the organic solvent comprises at least one of dichloromethane, trichloromethane, N,N-dimethylformamide, acetone, tetrahydrofuran.

[0031] [Method for preparing modified epoxy resin]

[0032] The method for preparing a modified epoxy resin provided by the present disclosure comprises the steps of: S1: reacting a bifunctional amine compound with a bifunctional isocyanate compound in an organic solvent to prepare a polyurea polymer; S2: adding a low molecular monooxy compound to an epoxy resin and stirring, then adding a curing agent amine compound and the polyurea polymer and stirring, removing bubbles in the system under vacuum negative pressure, and coating on the surface of a substrate to obtain a modified epoxy resin coating.

[0033] [For S1]

[0034] In some embodiments, the bifunctional amine compound comprises at least one of a polyamide, a polyetheramine, isophorone diamine, diethylenetriamine. In some embodiments, the bifunctional isocyanate compound comprises at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate. In some embodiments, the molar ratio of the bifunctional amine compound to the bifunctional isocyanate compound is (1-10):(0.1-10).

[0035] In some embodiments, the organic solvent comprises at least one of dichloromethane, trichloromethane, N,N-dimethylformamide, acetone, tetrahydrofuran.

[0036] In some embodiments, the reaction temperature in S1 is 10-120°C, and the reaction time is 2-24h.

[0037] In some embodiments, the step S1 is: dissolving the bifunctional amine compound in an organic solvent to form an organic solution, purging nitrogen to remove air in the device, and then placing in an ice water bath; adding the bifunctional isocyanate compound into the organic solution at a constant pressure to react, to obtain the polyurea polymer. In some embodiments, the constant pressure dropping is implemented by using a constant pressure dropping funnel. In some embodiments, the nitrogen purging time is 15 min to 30 min. In some embodiments, the reaction time is 15 h to 25 h.

[0038] [for S2]

[0039] In some embodiments, the epoxy resin comprises at least one of E51, E44, E20, E12.

[0040] In some embodiments, the curing agent amine compound comprises at least one of polyamide, polyether amine, isophorone diamine, diethylene triamine.

[0041] In some embodiments, the low molecular monooxy compound comprises at least one of n-butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, 5-ethyl hexyl glycidyl ether.

[0042] In some embodiments, the mass ratio of the epoxy resin to the low molecular monooxy compound is (1-20):(0.1-10).

[0043] In some embodiments, the mass ratio of the epoxy resin, the low molecular monooxy compound, the polyurea polymer, and the curing agent amine compound is (0.1-30):(0.1-30):(0.01-10):(0.01-10).

[0044] In some embodiments, the substrate comprises at least one of a metal substrate, a glass substrate, a ceramic substrate, an enamel substrate, a polymer substrate, and a composite substrate formed by the above substrates. In some embodiments, the metal substrate comprises carbon steel.

[0045] [Embodiments]

[0046] The present disclosure is further illustrated by the following examples. In the following examples and comparative examples, the reagents, materials and instruments used are commercially available or prepared by methods known in the art, unless otherwise specified.

[0047] Example 1

[0048] Take 10 g of epoxy E51 in a 100 mL beaker, add 10 g of n-butyl glycidyl ether; stir for 5 min; add 5 g of polyether amine, stir for 5 min; vacuum negative pressure for 1 h, remove bubbles, spin coating on the surface of Q235 carbon steel, to obtain self-repairing epoxy coating 1.

[0049] Example 2

[0050] Take 25 g of epoxy E20 in a 50 mL beaker, add 10 g of n-butyl glycidyl ether; stir for 5 min; add 5 g of polyether amine, stir for 5 min; vacuum negative pressure for 1 h, remove bubbles, spin coating on the surface of Q235 carbon steel, to obtain self-repairing epoxy coating 2.

[0051] Example 3

[0052] Take 40 g of epoxy E12 in a 50 mL beaker, add 10 g of n-butyl glycidyl ether; stir for 5 min; add 5 g of polyether amine, stir for 5 min; vacuum negative pressure for 1 h, remove bubbles, spin coating on the surface of Q235 carbon steel, to obtain self-repairing epoxy coating 3.

[0053] Example 4

[0054] Step 1: Take 80 g of polyether amine dissolved in 60 mL of anhydrous chloroform solution in a 250 mL three-necked flask, place 4.44 g of isophorone diisocyanate in a constant pressure burette, keep the air tightness of the reaction device, and introduce nitrogen for 20 min to remove air in the device; place the whole device in an ice water bath for 18 h; prepare polyurea polymer PI.

[0055] Step 2: Take 25 g of epoxy E20 in a 50 mL beaker, add 10 g of n-butyl glycidyl ether; stir for 5 min; add 5 g of polyether amine and 5 g of polyurea polymer PI, stir for 5 min; vacuum negative pressure for 1 h, remove bubbles, spin coating on the surface of Q235 carbon steel, to obtain self-repairing toughened epoxy coating 1.

[0056] Example 5

[0057] Step 1: Take 80 g of polyether amine dissolved in 60 mL of anhydrous chloroform solution in a 250 mL three-necked flask, place 4.44 g of isophorone diisocyanate in a constant pressure burette, keep the air tightness of the reaction device, and introduce nitrogen for 20 min to remove air in the device; place the whole device in an ice water bath for 18 h; prepare polyurea polymer PI.

[0058] Step 2: Take 25 g of epoxy E20 in a 50 mL beaker, add 10 g of n-butyl glycidyl ether; stir for 5 min; add 5 g of polyether amine and 10 g of polyurea polymer PI, stir for 5 min; vacuum negative pressure for 1 h, remove bubbles, spin coating on the surface of Q235 carbon steel, to obtain self-repairing toughened epoxy coating 2.

[0059] Example 6

[0060] Step 1: 80 g of polyether amine was dissolved in 60 mL of anhydrous chloroform solution in a 250 mL three-necked flask, 4.44 g of isophorone diisocyanate was placed in a constant pressure burette, the air-tightness of the reaction device was maintained, and nitrogen was introduced for 20 min to remove the air in the device; the whole device was placed in an ice water bath for 18 h; and a polyurea polymer PI was prepared.

[0061] Step 2: 25 g of epoxy E20 was weighed in a 50 mL beaker, 10 g of n-butyl glycidyl ether was added; stirred for 5 min; 5 g of polyether amine and 15 g of polyurea polymer PI were added, and stirred for 5 min; vacuum negative pressure for 1 h to remove bubbles, and spin-coated on the surface of Q235 carbon steel to obtain a self-repairing toughened epoxy coating 3.

[0062] Example 7

[0063] Step 1: 80 g of polyether amine was dissolved in 60 mL of anhydrous chloroform solution in a 250 mL three-necked flask, 4.44 g of isophorone diisocyanate was placed in a constant pressure burette, the air-tightness of the reaction device was maintained, and nitrogen was introduced for 20 min to remove the air in the device; the whole device was placed in an ice water bath for 18 h; and a polyurea polymer PI was prepared.

[0064] Step 2: 25 g of epoxy E20 was weighed in a 50 mL beaker, 10 g of n-butyl glycidyl ether was added; stirred for 5 min; 5 g of polyether amine and 15 g of polyurea polymer PI were added, and stirred for 5 min; vacuum negative pressure for 1 h to remove bubbles, and spin-coated on the surface of Q235 carbon steel to obtain a self-repairing toughened epoxy coating 3.

[0065] The substance parameters involved in Examples 1-7 are shown in Table 1. For ease of illustration, symbols are used in Table 1 to represent specific substances:

[0066] A: E51

[0067] B: E20

[0068] C: E12

[0069] D: n-butyl glycidyl ether

[0070] E: polyether amine

[0071] F: polyurea polymer PI

[0072] The self-repairing epoxy coatings 1-3 and the self-repairing toughened epoxy coatings 1-4 in Examples 1-7 were respectively subjected to infrared, adhesion, impact resistance, open circuit potential and electrochemical impedance spectroscopy tests, and the test results are shown in Table 2 and Table 3. Figure 1 -5.

[0073] Table 1. Parameters of the substances in Examples 1-7

[0074] Example number A / g B / g C / g D / g E / g F / g Example 1 10 - - 10 5 - Example 2 - 25 - 10 5 - Example 3 - - 40 10 5 - Example 4 - 25 - 10 5 5 Example 5 - 25 - 10 5 10 Example 6 - 25 - 10 5 15 Example 7 - 25 - 10 5 20

[0075] Note: "-" means not added.

[0076] In Figure 1 , seven groups of modified samples all appeared characteristic absorption peaks at 1100 cm -1 , which was caused by the stretching vibration of C-O bond in polyether amine; the characteristic absorption peaks of the seven groups of samples appeared at 1600 cm -1 , 1580 cm -1 , 1500 cm -1 and 1460 cm -1 had different intensities, which was caused by the stretching vibration of benzene ring in epoxy resin; at the same time, a wide and strong characteristic absorption peak was observed at 3200-3450 cm -1 for the seven groups of modified samples, which corresponded to the stretching vibration peak of -OH bond formed after the curing agent attacked the oxygen ring of epoxy resin through amino nucleophilic, which could prove the success of ring-opening addition polymerization; in addition, the characteristic peak of C-N bond could be observed at 1236 cm -1 , which also proved the successful preparation of the target product.

[0077] In Figure 2 , for the left graph, the adhesion of Example 1 was relatively weak, which was 6.19±0.46 MPa; the adhesion of Example 2 reached 9.32±0.69 MPa; and the adhesion of Example 3 was the lowest, which was only 5.98±0.45 MPa. For the right graph, after adding polyurea, the adhesion of modified epoxy resin gradually increased with the increasing content of polyurea, and the adhesion of Examples 4, 5, 6 and 7 was 10.53±0.51 MPa, 10.72±0.41 MPa, 10.82±0.68 MPa and 11.15±0.25 MPa, respectively.

[0078] In Figure 3 the left graph, with the increasing of benzene ring structure in epoxy resin, the rigidity was improved, which led to the decreasing trend of impact resistance. The impact resistance of Example 1 was the highest, which reached 90 Kg·cm, while the impact resistance of Example 2 decreased to 70 Kg·cm, and the impact resistance of Example 3 was the lowest, which was only 20 Kg·cm. In Figure 3 the right graph, with the increasing of polyurea content, the impact resistance of epoxy resin gradually increased, and the impact resistance of Examples 4, 5, 6 and 7 was 90 Kg·cm, 100 Kg·cm, 100 Kg·cm and 100 Kg·cm, respectively.

[0079] InFigure 4 , Figure 5 In the above examples, the open circuit potential and low frequency impedance (|Z| of the seven modified epoxy resin samples immersed in 3.5wt.% NaCl solution were measured. 0.01Hz The intact coating has high open circuit potential and low frequency impedance; after scratching, the open circuit potential and low frequency impedance decrease sharply; by observing whether the open circuit potential and low frequency impedance are restored after repair treatment, it can be judged whether it has self-repairing performance. The modified epoxy resins of Examples 1-3 achieve self-repairing effect by reducing crosslinking density and improving chain segment movement ability; but the mechanical properties are weak. Examples 4-7 improve the mechanical strength of the self-repairing epoxy resin by adding polyurea; the addition of polyurea will react with epoxy groups to increase the crosslinking density, and the self-repairing performance will decrease; however, the hydrogen bonds between polyurea promote the self-repairing performance, so the self-repairing performance of Examples 5-6 is low, but when the polyurea addition amount reaches a certain degree, the self-repairing effect will be improved. Figure 4 , Figure 5 The results of Examples 2, 3, 4 and 7 show that in the above examples, Examples 2, 3, 4 and 7 have good self-repairing performance.

[0080] In summary, the modified epoxy resin coating provided by the present disclosure reduces the crosslinking density of the coating by adding a low molecular monooxy compound, achieves self-repairing performance; the addition of polyurea polymer increases the soft segment and improves the toughness of the epoxy coating; and the polyurea polymer is rich in hydrogen bonds, and the supramolecular force is helpful to improve the self-repairing performance of the epoxy coating.

[0081] The above description is only an example of the present disclosure, and does not limit the present disclosure in any form. Although the present disclosure discloses the above as a preferred embodiment, it is not intended to limit the present disclosure, and any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present disclosure, which are equivalent to equivalent embodiments, and are within the scope of the technical solution of the present disclosure.

Claims

1. A modified epoxy resin, the raw materials of which include epoxy resin and curing agent amine compound, characterized in that, It also includes low-molecular-weight monoepoxy compounds and polyurea polymers; The mass ratio of the epoxy resin, the low molecular weight monoepoxy compound, the curing agent amine compound, and the polyurea polymer is 25:10:5:(0.01~5) or 25:10:5:

20. The epoxy resin is epoxy E20; the low molecular weight monoepoxy compound includes at least one of n-butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, and 5-ethylhexyl glycidyl ether. The polyurea polymer includes compounds prepared by reacting a difunctional amine compound with a difunctional isocyanate compound in an organic solvent; The bifunctional amine compound includes at least one of polyamide, polyetheramine, isoflavone diamine, and diethylenetriamine; The bifunctional isocyanate compound includes at least one of isoflavone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

2. A method for preparing the modified epoxy resin as described in claim 1, characterized in that, Including the following steps: S1: A polyurea polymer is prepared by reacting a difunctional amine compound with a difunctional isocyanate compound in an organic solvent. S2: Add a low molecular weight monoepoxy compound to the epoxy resin and stir. Then add the curing agent amine compound and the polyurea polymer and stir. After removing the air bubbles in the system under vacuum negative pressure, coat it onto the substrate surface to obtain a modified epoxy resin coating.

3. The method for preparing the modified epoxy resin according to claim 2, characterized in that, The reaction temperature in step S1 is 10~120℃, and the reaction time is 2~24h.

4. The method for preparing the modified epoxy resin according to claim 2, characterized in that, In step S1, the molar ratio of the difunctional amine compound to the difunctional isocyanate compound is (1~10):(0.1~10).

5. The method for preparing the modified epoxy resin according to claim 2, characterized in that, Step S1 is as follows: dissolve the bifunctional amine compound in an organic solvent to form an organic solution, pass nitrogen gas through the device to remove air, and then place it in an ice-water bath; add the bifunctional isocyanate compound dropwise into the organic solution at constant pressure to react and obtain a polyurea polymer.

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