Self-repairing anticorrosive composite epoxy resin coating material, preparation method and application thereof

Abstract

The application discloses a self-repairing anticorrosive composite epoxy resin coating as well as a preparation method and application thereof. The composite epoxy resin coating is prepared from raw materials including grafted-lignin graphene oxide and double-bond-terminated epoxy resin. The grafted-lignin graphene oxide is prepared from double-bonded lignin and graphene oxide. The composite coating prepared from the composite epoxy resin coating not only has good anticorrosive performance, but also has excellent self-repairing performance, thereby being beneficial to prolonging the service life of metal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paint, in particular to a self-repairing anticorrosive composite epoxy resin paint, a preparation method and application thereof. BACKGROUND

[0002] At present, although modified nano fillers represented by graphene and carbon nanotubes can improve the anticorrosive performance of resin coating through physical shielding and corrosion inhibition effect, the poor dispersibility and interface compatibility of the fillers in the resin matrix are still technical bottlenecks. The agglomeration effect easily forms microdefects and weakens the interface bonding strength, resulting in discontinuous anticorrosive network. For the research and development of self-repairing anticorrosive composite epoxy resin paint, the existing technology mostly uses petroleum-based modifiers (such as silane coupling agent, polymer coating agent) to improve the dispersibility of fillers, but the interface matching of such hydrophobic modifiers with polar resins is insufficient, and phase separation is easily induced during the curing process, making it difficult to build a stable self-repairing microcapsule delivery system. In contrast, biomass-derived materials (such as lignin, chitosan) are rich in active groups such as hydroxyl and amino groups, which can be modified by green chemistry to endow nano fillers with excellent dispersibility and interface reactivity. At the same time, the multi-level structure can synergistically enhance the self-repairing ability and corrosion medium barrier performance of the coating, providing a new idea for the development of environmentally friendly high-performance anticorrosive coatings and meeting the demand for the use of renewable resources. Therefore, using renewable and abundant biomass materials to modify nano fillers is a feasible strategy to solve the above problems. SUMMARY

[0003] The present application aims to at least solve one of the above-mentioned technical problems in the prior art. To this end, the object of the present application is to provide a self-repairing anticorrosive composite epoxy resin paint, a preparation method and application thereof.

[0004] In order to achieve the above-mentioned object, the technical solution adopted by the present application is as follows:

[0005] In a first aspect of the present application, a composite epoxy resin paint is provided, which is prepared from raw materials including grafted lignin graphene oxide and double-bond terminated epoxy resin; the grafted lignin graphene oxide is prepared from double-bonded lignin and graphene oxide.

[0006] In the present application, during the process of forming grafted lignin graphene oxide from double-bonded lignin and graphene oxide, the double-bonded lignin acts as an intercalating agent, increasing the spacing between graphene oxides and improving their dispersibility and interface interaction; the grafted lignin graphene oxide and the double-bond terminated epoxy resin undergo free radical polymerization, thereby forming a paint and endowing the paint with self-repairing anticorrosive performance.

[0007] In some embodiments of the present application, in the grafted lignin graphene oxide, the lignin is grafted on the graphene oxide through a six-membered ring alkenyl group.

[0008] In some embodiments of the present application, the graphene oxide grafted with lignin accounts for 0.01wt% to 10wt% in the composite epoxy coating, such as 0.1wt% to 8.0wt%, 0.5wt% to 7.0wt%, 1wt% to 5.0wt%, etc.

[0009] In some embodiments of the present application, the mass ratio of the double-bonded lignin to the graphene oxide is (0.1-10):(0.1-50), such as (1-10):(1-50), 1:3-10, 1:4-8, 1:4-6, etc.

[0010] In some embodiments of the present application, the double-bonded lignin is provided with double bonds by a double-bond monomer, which includes at least one of allyl bromide, allyl iodide, 6-bromo-1-hexene, allyl ether, 10-undecenol.

[0011] In some embodiments of the present application, the double-bonded lignin is prepared from a double-bond monomer and lignin.

[0012] In some embodiments of the present application, the graphene oxide further includes pyridyl-containing graphene oxide. In the present application, the pyridyl groups on the pyridyl-containing graphene oxide can form chelates with metal ions. When the coating is applied to the metal corrosion interface, the pyridyl groups can form chelates with iron ions to cover the metal corrosion area, thereby isolating the corrosion medium from the metal and improving the corrosion performance of the coating.

[0013] In some embodiments of the present application, the pyridyl-containing graphene oxide is prepared from a pyridyl monomer and graphene oxide.

[0014] In some embodiments of the present application, the pyridyl monomer includes at least one of 4'-(4-chlorophenyl)-2,2':6',2"-terpyridine, 4'-bromo-2,2':6',2"-terpyridine, 4'-(4-fluorophenyl)-2,2':6',2"-terpyridine, 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, 6,6"-dibromo-2,2':6',2"-terpyridine, 4'-(4-aminophenyl)-2,2':6',2-terpyridine.

[0015] In some embodiments of the present application, the double-bond terminated epoxy resin is prepared from an epoxy resin, an amino monomer, and an acrylic monomer.

[0016] In some embodiments of the present application, the mass ratio of the epoxy resin, the amino monomer and the acrylic monomer is (1-150):(0.1-50):(1-100), such as (10-100):(0.5-10):(6-30), (30-80):(1-5):(10-25), etc.

[0017] In some embodiments of the present application, the epoxy resin comprises at least one of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a polyphenol type glycidyl ether epoxy resin, a glycidyl ether type epoxy resin, a heterocyclic type epoxy resin.

[0018] In some embodiments of the present application, the epoxy resin comprises at least one of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a polyphenol type glycidyl ether epoxy resin, a glycidyl ether type epoxy resin, a heterocyclic type epoxy resin.

[0019] In some embodiments of the present application, the amino monomer comprises at least one of 3-butoxypropylamine, ethylenediamine, aniline, acrylamide, 2-aminopurine, glucosamine.

[0020] In some embodiments of the present application, the acrylic monomer comprises at least one of acrylic acid, methacrylic acid, 2-fluoroacrylic acid, 2-propylacrylic acid.

[0021] In a second aspect of the present application, a preparation method of the composite epoxy resin coating is provided, comprising the following steps:

[0022] The grafted lignin graphene oxide, the double bond terminated epoxy resin and the styrene are subjected to a polymerization reaction to obtain the composite epoxy resin coating.

[0023] In the present application, the styrene solvent is used to participate in the free radical polymerization reaction, which effectively avoids the volatilization of the solvent and has environmental protection.

[0024] In some embodiments of the present application, the mass ratio of the styrene and the double bond terminated epoxy resin is 1:19-7:3.

[0025] In some embodiments of the present application, the polymerization reaction is carried out under the action of an auxiliary agent; the mass ratio of the auxiliary agent and the double bond terminated epoxy resin is 1:(1-10).

[0026] In some embodiments of the present application, the auxiliary agent comprises at least two of cobalt naphthenate, 2-butanone peroxide, 2,2,6,6-tetramethyl-1-piperidinyloxy, azobisisobutyronitrile, dibenzoyl peroxide, dicumyl peroxide.

[0027] In some embodiments of the present application, the preparation method of the composite epoxy resin coating comprises the following steps: dissolving the double bond terminated epoxy resin into styrene, then adding the grafted lignin graphene oxide, and ultrasonic dispersing for 10-40 min; then adding the additives, and ultrasonic dispersing for 1-120 min, and performing polymerization reaction to obtain the composite epoxy resin coating; preferably, the ultrasonic frequency of the ultrasonic dispersing is 50-500 Hz.

[0028] In some embodiments of the present application, the preparation method of the grafted lignin graphene oxide comprises the following steps: ultrasonic dispersing the graphene oxide, the double bond lignin and the polymerization inhibitor in a solvent, and performing heating reaction to obtain the grafted lignin graphene oxide. In the present application, Diels-Alder Reaction occurs between the double bond on the double bond lignin and the conjugated double bond on the graphene oxide, so that the lignin is grafted on the graphene oxide.

[0029] In some embodiments of the present application, the ultrasonic frequency of the ultrasonic dispersing is 50-500 Hz; and the ultrasonic dispersing time is 10-60 min.

[0030] In some embodiments of the present application, the heating reaction is performed in a high-pressure reaction kettle; the reaction temperature of the heating reaction is 80-200 ℃; and the reaction time of the heating reaction is 2-36 h.

[0031] In some embodiments of the present application, the mass ratio of the graphene oxide to the solvent is (0.1-50):(10-120); and the solvent comprises at least one of N-methyl pyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, chloroform, dimethyl sulfoxide and toluene.

[0032] In some embodiments of the present application, the preparation method of the grafted lignin graphene oxide further comprises a purification treatment on the reaction product; the specific operation of the purification treatment comprises centrifuging, washing and drying the reaction product; the washing is performed by using a second solvent; and the second solvent comprises at least one of water, anhydrous ethanol, hexane, toluene, tetrahydrofuran and methanol.

[0033] In some embodiments of the present application, the preparation method of the double bond terminated epoxy resin comprises the following steps: performing ring-opening reaction of the epoxy resin and an amino monomer, adding a polymerization inhibitor and a phase transfer catalyst, then adding an acrylic monomer to perform end-capping reaction, and obtaining the double bond terminated epoxy resin.

[0034] In some embodiments of the present application, the ring-opening reaction is performed at 60-150 ℃ and 80-200 ℃ respectively for 1-18 h.

[0035] In some embodiments of the present application, the reaction system is cooled to 10-80°C before adding the polymerization inhibitor and the phase transfer catalyst.

[0036] In some embodiments of the present application, the reaction system is heated to 80-180°C before adding the acrylic monomer.

[0037] In some embodiments of the present application, the reaction temperature of the end-capping reaction is 90-200°C; and the induction time of the end-capping reaction is 1-24h.

[0038] In a third aspect of the present application, a coating layer is provided, which is prepared by curing the composite epoxy resin coating.

[0039] In some embodiments of the present application, the curing temperature is 80-200°C; and the curing time is 1-10h, such as 1-5h.

[0040] In a fourth aspect of the present application, the composite epoxy resin coating or the coating layer is provided for use in corrosion prevention of metal products.

[0041] In some embodiments of the present application, the metal products include any one of marine engineering equipment, ships, oil and chemical transportation pipelines, and building materials.

[0042] The present application has the following advantages:

[0043] (1) The lignin used in the present application is derived from artificial forests or paper pulp, which realizes the purpose of turning waste into treasure. In addition, the lignin grafted onto the nanofiller acts as an intercalating agent to improve the dispersion of the nanofiller in the resin and the interfacial interaction, and the lignin can form a chelate with metal ions to improve the corrosion resistance of the coating. Most importantly, the use of lignin reduces the amount of petroleum-based products, promoting the development of the corrosion-resistant coating field towards green and sustainable direction.

[0044] (2) The epoxy resin, ammonia monomer and acrylic monomer used in the present application are low in price and simple in preparation method, and the synthesized double-bond-terminated epoxy resin has good corrosion resistance and is convenient for industrial production.

[0045] (3) The composite coating prepared in the present application not only has good corrosion resistance, but also has excellent self-repairing performance, which is beneficial to prolong the service life of the metal.

[0046] (4) The lignin grafted graphene oxide / oxidized graphene containing pyridyl group (GO / TGO), double-bond-terminated epoxy resin and composite coating prepared in the present application have relatively simple reaction conditions and are easy to operate.

[0047] (5) The styrene solvent participates in the free radical polymerization reaction in the preparation process of the composite coating of the present application, effectively avoiding the volatilization of the solvent, protecting the environment, reducing the harm to the construction personnel, and having the green environmental protection characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 The reaction route map for preparing the double bond-terminated epoxy resin of the present application.

[0049] Figure 2 The reaction route map for preparing the composite coating of the present application.

[0050] Figure 3 The infrared structure of the double bond-terminated epoxy resin of the present application.

[0051] Figure 4 The Bode diagram of the coating (ABE) prepared from the double bond-terminated epoxy resin of the present application.

[0052] Figure 5 The Bode result of the lignin-grafted GO composite coating (LGO-ABE) of the present application.

[0053] Figure 6 The Bode result of the lignin-grafted TGO composite coating (LTGO-ABE) of the present application.

[0054] Figure 7 The morphology diagram of the scratch ABE coating of the present application.

[0055] Figure 8 The morphology diagram of the scratch LGO-ABE composite coating of the present application.

[0056] Figure 9 The morphology diagram of the scratch LTGO-ABE composite coating of the present application. DETAILED DESCRIPTION

[0057] The content of the present application is further illustrated in detail through specific examples. The raw materials, reagents or devices used in the examples and comparative examples can be obtained from the conventional commercial channels or can be obtained by the prior art methods, unless otherwise specified. Unless otherwise specified, the test or test method is the conventional method in the art.

[0058] In the following examples or comparative examples, the preparation method of double-bonded lignin refers to Chang-An Xu et al. Mimosainspired intelligent anti-corrosive composite coating by incorporating lignin and pyridine derivatives grafted graphene oxide. Chemical Engineering Journal. 2024, 483, 149316 (DOI: 10.1016 / j.cej.2024.149316)

[0059] In the following examples or comparative examples, the preparation method of lignin-grafted GO / TGO is as follows: 0.1 g of GO / TGO, 0.02 g of double-bonded lignin and 0.00048 g of polymerization inhibitor are added into 50 g of N-methylpyrrolidone solvent, and ultrasonic dispersion is performed for 30 min, then the mixture is transferred into a high-pressure reactor, and reaction is performed at 100°C for 6 h. After centrifugation, the mixture is rinsed with anhydrous ethanol. Finally, the mixture is dried in an oven overnight to obtain lignin-grafted GO / TGO. The material obtained by reacting lignin and GO is marked as LGO, and the material obtained by reacting lignin and TGO is marked as LTGO.

[0060] Figure 1 A reaction route diagram of double-bond-terminated epoxy resin is shown, and in the following examples and comparative examples, the preparation method of double-bond-terminated epoxy resin is as follows: 60 g of epoxy resin and 3.275 g of 3-butoxypropylamine are added into a flask, and heating is performed at 100°C and 150°C for 2 h. Then the system temperature is reduced to room temperature, 0.01574 g of polymerization inhibitor and 0.3935 g of benzyltriethylammonium chloride are added. After heating to 90°C, 15.43 g of acrylic acid is slowly added into the flask, and reaction is performed at 110°C under nitrogen atmosphere for 3 h. Finally, after reducing the system temperature to 70°C, 33.73 g of styrene is added and stirred for 15 min to obtain a double-bond-terminated epoxy resin solution.

[0061] Example 1

[0062] In this example, a composite epoxy resin coating is prepared, Figure 2 A reaction route diagram of the coating is shown, and the specific process is as follows:

[0063] A solution of 3.0 g of double bond terminated epoxy resin, 0.003 g of LGO was added to a glass bottle and sonicated, followed by the addition of 0.009 g of cobalt naphthenate and 0.03 g of 2-butanone peroxide and sonicated further. This was then spread onto stainless steel 304 using an applicator and left at room temperature overnight before being cured at 100°C, 120°C and 160°C for 3h, 4h and 2h respectively. The resulting coating was labelled LGO-ABE.

[0064] Example 2

[0065] A composite epoxy coating was prepared according to the following procedure:

[0066] A solution of 3.0 g of double bond terminated epoxy resin, 0.003 g of LGO was added to a glass bottle and sonicated, followed by the addition of 0.009 g of cobalt naphthenate and 0.03 g of 2-butanone peroxide and sonicated further. This was then spread onto stainless steel 304 using an applicator and left at room temperature overnight before being cured at 100°C, 120°C and 160°C for 3h, 4h and 2h respectively. The resulting coating was labelled LGO-ABE.

[0067] Comparative Example 1

[0068] A composite epoxy coating was prepared according to the following procedure:

[0069] A solution of 3.0 g of double bond terminated epoxy resin, 0.003 g of LGO was added to a glass bottle and sonicated, followed by the addition of 0.009 g of cobalt naphthenate and 0.03 g of 2-butanone peroxide and sonicated further. This was then spread onto stainless steel 304 using an applicator and left at room temperature overnight before being cured at 100°C, 120°C and 160°C for 3h, 4h and 2h respectively. The resulting coating was labelled LGO-ABE.

[0070] Test Example

[0071] The coatings prepared in the examples and comparative examples were characterised according to the following procedure:

[0072] Test Methods:

[0073] (1) Chemical structure characterisation

[0074] Test Method: The functional groups of the samples were characterised by Fourier transform infrared spectroscopy (FTIR, Nicolet iS10, Germany). The wavelength range tested was 4000-500 cm -1 , with 32 scans.

[0075] (2) Electrochemical testing

[0076] Test method: Electrochemical test data of the coating was obtained by using electrochemical workstation (CHI-660E). During the test, the corrosive medium was 3.5wt% saline, Ag / AgCl electrode was used as reference electrode, and platinum plate was used as counter electrode.

[0077] (3) Self-repairing performance test

[0078] Test method: A sharp scalpel was used to draw a scratch on the surface of the coating, and then it was immersed in saline for 3 days. The morphology of the scratch was observed by scanning electron microscope.

[0079] Test results:

[0080] The performance test results of the coating prepared from the composite coating prepared in Examples 1-2 and Comparative Example 1 are shown in Table 1.

[0081] Table 1

[0082] / Example 1 Example 2 Comparative Example 1 Impedance modulus of coating (Ωcm 2 )]]> 4.79 x 10 7 ]] 6.76 x 10 8 ]] 1.17 x 10 9 ]]

[0083] Figure 3 The infrared structure diagram of the double bond-terminated epoxy resin.

[0084] Figures 4 to 6 Corresponding to the Bode results of Comparative Example 1, Example 1, and Example 2 coatings, respectively; Figures 7 to 9 Corresponding to the morphology of the scratch after immersion of Comparative Example 1, Example 1, and Example 2 coatings, respectively.

[0085] It can be found from Figure 2 that the intermediate product B-E44 and the final product AB-E44 both retain the main characteristic peaks of the raw material epoxy resin E44. For B-E44, the hydroxyl peak is reduced from 3493 cm -1 to 3440 cm -1 , which is due to the reaction of amino and epoxy groups to generate more hydroxyl groups, resulting in the enhancement of intermolecular hydrogen bonding of B-E44. At the same time, the epoxy group peak of B-E44 at 915 cm -1 is reduced, and a C-N characteristic peak is detected at 1461 cm -1 . For AB-E44, the epoxy characteristic peak disappears, and with the further increase of the number of hydroxyl groups, the hydroxyl peak decreases to 3430 cm -1 . It is worth noting that the ester group and double bond of AB-E44 are located at 1725 cm -1 and 1634 cm -1 , respectively, which indicates that the double bond-terminated epoxy resin has been successfully prepared.

[0086] It can be found from Figure 4 , Figure 5 , Figure 6As can be seen from Table 1, the coatings have similar impedance values at the beginning of the immersion, and the modulus of the coatings decreases after the coatings are immersed in the salt water for 120 days, which indicates that the corrosion resistance of the coatings is time-dependent, and the corrosion resistance of the coatings deteriorates with the extension of time. The modulus of the control coating decreases to 4.79 x 10 7 Ωcm 2 , and the corrosion resistance of the coating is the worst. After the introduction of the LGO and LTGO reinforcing fillers into the coating, the corrosion resistance of the coating is effectively improved, and the modulus of the coatings LGO-ABE and LTGO-ABE is 6.76 x 10 8 Ωcm 2 and 1.17 x 10 9 Ωcm 2 , which is higher than the control coating by more than one and two orders of magnitude, and the corrosion resistance of the LTGO-ABE coating is the best.

[0087] As can be seen from Figure 7 , Figure 8 and Figure 9 , a large amount of loose corrosion products is found at the scratch of the scratch coating ABE after the coating is immersed in the salt water for 3 days, which indicates that the coating does not have self-repairing performance. The corrosion products at the scratch of the coatings LGO-ABE and LTGO-ABE are less, and a relatively dense protective layer is formed at the scratch of the LTGO-ABE, which is the result of the product formed by the chelation of the lignin and pyridine groups and metal ions covering the scratch. It is found by comparison that the coating LTGO-ABE has excellent self-repairing corrosion resistance.

[0088] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be included in the protection scope of the present application.

Claims

1. A composite epoxy coating characterized by: The composite epoxy resin coating is prepared from raw materials including grafted lignin graphene oxide and double bond terminated epoxy resin; the grafted lignin graphene oxide is prepared from double bond lignin and graphene oxide; in the grafted lignin graphene oxide, the lignin is grafted on the graphene oxide through a six-membered ring alkenyl group; the graphene oxide further includes pyridyl-containing graphene oxide; the double bond terminated epoxy resin is prepared from epoxy resin, amino monomer and acrylic monomer; in the composite epoxy resin coating, the grafted lignin graphene oxide accounts for 0.01wt%-10wt%; the mass ratio of the double bond lignin to the graphene oxide is (0.1-10):(0.1-50).

2. The composite epoxy coating of claim 1, wherein: The double bond lignin is prepared from double bond monomer and lignin; the double bond monomer includes at least one of allyl bromide, allyl iodide, 6-bromo-1-hexene, allyl ether and 10-undecenol.

3. The composite epoxy coating of claim 1, wherein: The pyridyl-containing graphene oxide is prepared from pyridyl monomer and graphene oxide; the pyridyl monomer includes at least one of 4'-(4-chlorophenyl)-2,2':6',2"-terpyridine, 4'-bromo-2,2':6',2"-terpyridine, 4'-(4-fluorophenyl)-2,2':6',2"-terpyridine, 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, 6,6"-dibromo-2,2':6',2"-terpyridine and 4'-(4-aminophenyl)-2,2':6',2-terpyridine.

4. The composite epoxy coating of claim 1, wherein: The composite epoxy resin coating satisfies at least one of the following conditions: (I) the mass ratio of the epoxy resin, the amino monomer and the acrylic monomer is (1-150):(0.1-50):(1-100); (II) the epoxy resin includes an epoxy group terminated by an epoxy group; (III) the epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether type epoxy resin and heterocyclic type epoxy resin; (IV) the amino monomer includes at least one of 3-butoxypropylamine, ethylenediamine, aniline, acrylamide, 2-aminopurine and glucosamine; (V) the acrylic monomer includes at least one of acrylic acid, methacrylic acid, 2-fluoroacrylic acid and 2-propylacrylic acid.

5. The composite epoxy coating of claim 1, wherein: The structural formula of the double bond-terminated epoxy resin is: ; wherein R is .

6. A process for the preparation of a composite epoxy coating according to any one of claims 1 to 5, characterized in that: The following steps are included: polymerizing the grafted lignin graphene oxide, the double bond terminated epoxy resin and styrene to prepare the composite epoxy resin coating.

7. A coating layer prepared from curing the composite epoxy resin coating according to any one of claims 1-5.

8. Application of the composite epoxy resin coating according to any one of claims 1-5 or the coating layer according to claim 7 in corrosion protection of metal products.

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