Anticorrosive polyurethane coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of anticorrosive coatings, and particularly relates to an anticorrosive polyurethane coating as well as a preparation method and application thereof. The anticorrosive polyurethane coating comprises polyurethane resin, modified graphene, a curing agent and a solvent, alkoxy silane is grafted on the surface of the modified graphene, and the number of layers of the modified graphene is less than or equal to 4. The anticorrosive polyurethane coating disclosed by the invention has the beneficial effects that the anticorrosive polyurethane coating disclosed by the invention can form a compact physical barrier by mixing graphene with few lamellas and a large radius-thickness ratio with polyurethane resin, and also can play a role in toughening; graphene is adopted as modified graphene grafted with alkoxy silane, the graphene-resin interface bonding force is improved by adding the modified graphene, the graphene is stably dispersed in the resin, and the graphene is induced to be directionally arranged in the curing process so as to enhance the adhesion performance of the graphene; by optimizing the addition amount of graphene, on the premise that the thickness of the coating is not increased, the shielding property of the coating is remarkably enhanced, and meanwhile excellent adhesive force and impact resistance are kept.

Description

Technical Field

[0001] This application belongs to the field of anti-corrosion coating technology, specifically relating to an anti-corrosion polyurethane coating, its preparation method, and its application. Background Technology

[0002] In fields such as marine engineering, petrochemicals, and bridge construction, metal structures are exposed to harsh environments with high humidity, high salinity, and strong ultraviolet radiation for extended periods, requiring high corrosion resistance to meet usage requirements. Polyurethane topcoats, due to their excellent weather resistance, mechanical properties, and decorative properties, are the most commonly used topcoat in anti-corrosion systems. However, traditional polyurethane topcoats still face challenges such as penetrating corrosion from water, oxygen, and corrosive media during long-term use, adhesion degradation, and insufficient mechanical properties. Existing technologies improve the performance of polyurethane topcoats by adding shielding fillers (such as mica iron oxide and glass flakes), but the filler content needs to reach greater than 25 wt% to be effective, which leads to a significant decrease in coating flexibility. Existing technologies also enhance the anti-corrosion performance of polyurethane by adding graphene, but graphene is prone to agglomeration, has poor dispersion stability, and weak bonding with the resin interface, which can actually accelerate coating delamination. Therefore, there is an urgent need for an anti-corrosion polyurethane topcoat with excellent shielding performance, high mechanical strength, and strong adhesion. Summary of the Invention

[0003] This application provides an anti-corrosion polyurethane coating, its preparation method, and its application, aiming to solve the problems of poor anti-corrosion performance, insufficient adhesion, and mechanical properties that cannot meet the application requirements of existing polyurethane coatings.

[0004] The first aspect of this application provides an anti-corrosion polyurethane coating, comprising polyurethane resin, modified graphene, curing agent, and solvent;

[0005] The modified graphene has alkoxysilane grafted onto its surface, and the number of layers in the modified graphene is ≤4.

[0006] The anti-corrosion polyurethane coating described in this application uses graphene modified with alkoxysilane grafts. The addition of modified graphene can improve the interfacial bonding force between graphene and resin, so that graphene is stably dispersed in the resin and induces graphene to oriented and align during the curing process to enhance its adhesion performance.

[0007] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the raw materials include the following parts by weight: 30-55 parts of polyurethane resin, 0.5-6 parts of modified graphene, 12-24 parts of curing agent, and 12-30 parts of solvent.

[0008] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the aspect ratio of the modified graphene is ≥240:1.

[0009] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the oxygen content of the modified graphene is ≤4.5 at%.

[0010] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the grafting rate of the modified graphene on the alkoxysilane is 5-15 wt%.

[0011] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the alkoxysilane includes γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane.

[0012] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the curing agent includes a polyisocyanate curing agent. For example, toluene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate.

[0013] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the solvent includes xylene and / or butanol.

[0014] According to some embodiments of the anti-corrosion polyurethane coating described in this application, it also includes 1-5 parts of additives and 6-15 parts of anti-corrosion pigments.

[0015] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the additives include dispersants.

[0016] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the dispersant includes BYK-163 dispersant.

[0017] According to some embodiments of the anti-corrosion polyurethane coating described in this application, the anti-corrosion pigment includes one or more of phosphorus iron powder, mica iron oxide, and zinc chromium yellow.

[0018] A second aspect of this application provides a method for preparing the anti-corrosion polyurethane coating described in the first aspect of this application, comprising the following steps:

[0019] (1) Preparation of modified graphene:

[0020] (2) The modified graphene, polyurethane resin, curing agent, solvent, optional additives and anti-corrosion pigments are mixed to obtain the anti-corrosion polyurethane coating.

[0021] According to some embodiments of the preparation method of the anti-corrosion polyurethane coating described in this application, the preparation method of the modified graphene includes the following steps:

[0022] a. Mix graphene oxide and hydrazine hydrate and carry out a reduction reaction to obtain reduced graphene oxide;

[0023] b. Mix the reduced graphene oxide and alkoxysilane and carry out an esterification reaction;

[0024] c. The esterification reaction product is subjected to ultrasonic exfoliation to obtain the modified graphene.

[0025] According to some embodiments of the preparation method of the anti-corrosion polyurethane coating described in this application, the esterification reaction temperature is 60-80℃ and the esterification reaction time is 2-4h.

[0026] The third aspect of this application provides an application of the anti-corrosion polyurethane coating described in the first aspect of this application or the anti-corrosion polyurethane coating prepared by the method described in the second aspect of this application in the corrosion protection of metal substrates.

[0027] According to some embodiments of the application described in this application, the metal substrate includes offshore wind power equipment, oil pipelines, or bridge equipment.

[0028] The beneficial effects of this application include: the anti-corrosion polyurethane coating described in this application uses graphene with fewer flakes and a large aspect ratio, which is mixed with polyurethane resin to form a dense physical barrier and also plays a toughening role; in addition, the graphene used in this application is modified graphene grafted with alkoxysilanes. The addition of modified graphene can improve the interfacial bonding force between graphene and resin, so that graphene is stably dispersed in resin and induces graphene to oriented and align during curing to enhance its adhesion performance; by optimizing the amount of graphene added, the shielding performance of the coating can be significantly enhanced without increasing the coating thickness, while maintaining excellent adhesion and impact resistance.

[0029] The anti-corrosion polyurethane coating described in this application has excellent anti-corrosion properties, as well as high adhesion and impact resistance. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0032] This application provides an anti-corrosion polyurethane coating, comprising polyurethane resin, modified graphene, curing agent, and solvent;

[0033] The modified graphene has alkoxysilanes grafted onto its surface, and the number of layers in the modified graphene is ≤4. Modified graphene with fewer layers can form a dense physical barrier with the resin, while also providing toughening.

[0034] By grafting and modifying graphene, the interfacial bonding force between graphene and resin can be improved, enabling graphene to be stably dispersed in the resin and inducing the directional alignment of graphene during the curing process.

[0035] In some embodiments of this application, the raw materials include the following parts by weight: 30-55 parts of polyurethane resin, 0.5-6 parts of modified graphene, 12-24 parts of curing agent, and 12-30 parts of solvent.

[0036] In some embodiments of this application, the raw materials include the following parts by weight: 40-50 parts of polyurethane resin, 3-5 parts of modified graphene, 15-20 parts of curing agent, and 12-30 parts of solvent.

[0037] In some embodiments of this application, the raw materials include the following parts by weight: 35-50 parts of polyurethane resin, 1-5 parts of modified graphene, 15-20 parts of curing agent, and 15-30 parts of solvent.

[0038] In some embodiments of this application, the modified graphene has an aspect ratio ≥ 240:1; for example, 240:1, 246:1, 250:1, 256:1, 260:1, etc. The aspect ratio of graphene refers to the ratio of its radial dimension to its thickness, used to describe the shape characteristics of its two-dimensional structure. Graphene with fewer sheets and a large aspect ratio can form a dense physical barrier with resin, while also providing toughening.

[0039] In some embodiments of this application, the oxygen content of the modified graphene is ≤4.5at%; for example, 4.5at%, 4.0at%, 3.8at%, 3.5at%, 3.0at%, 2.8at% etc.

[0040] In some embodiments of this application, the grafting rate of alkoxysilane on the modified graphene is 5-15 wt%, such as 5 wt%, 8 wt%, 12 wt%, 13 wt%, 15 wt%, etc.

[0041] In some embodiments of this application, the alkoxysilane includes γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane.

[0042] In some embodiments of this application, the curing agent includes a polyisocyanate curing agent.

[0043] In some embodiments of this application, the solvent includes xylene and / or butanol.

[0044] In some embodiments of this application, it also includes 1-5 parts of additives and 6-15 parts of anti-corrosion pigments.

[0045] In some embodiments of this application, the adjuvant includes a dispersant.

[0046] In some embodiments of this application, the dispersant includes BYK-163 dispersant;

[0047] In some embodiments of this application, the anti-corrosion pigment includes one or more of ferrophosphorus powder, ferric oxide mica, and zinc chromium yellow.

[0048] This application also provides a method for preparing the anti-corrosion polyurethane coating described in the first aspect of this application, comprising the following steps:

[0049] (1) Preparation of modified graphene:

[0050] (2) The modified graphene, polyurethane resin, curing agent, solvent, optional additives and anti-corrosion pigments are mixed to obtain the anti-corrosion polyurethane coating.

[0051] In some embodiments of this application, the method for preparing the modified graphene includes the following steps:

[0052] a. Mix graphene oxide and hydrazine hydrate and carry out a reduction reaction to obtain reduced graphene oxide;

[0053] b. Mix reduced graphene oxide and alkoxysilane to carry out an esterification reaction;

[0054] c. The esterification reaction product is subjected to ultrasonic exfoliation to obtain the modified graphene.

[0055] In some embodiments of this application, the temperature of the esterification reaction is 60-80°C, such as 60°C, 65°C, 68°C, 73°C, 76°C, 80°C, etc., and the time of the esterification reaction is 2-4 hours, such as 2 hours, 3 hours, 4 hours, etc.

[0056] This application also provides an application of the anti-corrosion polyurethane coating described in the first aspect of this application or the anti-corrosion polyurethane coating prepared by the method described in the second aspect of this application in the corrosion protection of metal substrates. The coating of this application possesses excellent adhesion and impact resistance, and is suitable for corrosion protection of steel structure equipment in marine engineering projects designed for 25 years.

[0057] In some embodiments of this application, the metal substrate includes offshore wind power equipment, oil pipelines, or bridge equipment.

[0058] The technical solution of this application will be further described below with reference to specific embodiments.

[0059] Example 1

[0060] A method for preparing an anti-corrosion polyurethane coating includes the following steps:

[0061] (1) Mix 5g of graphene oxide and 150mg of hydrazine hydrate, adjust the pH of the mixture to 9, and reduce it to obtain reduced graphene oxide; mix 5g of reduced graphene oxide and 1g of γ-aminopropyltriethoxysilane at 70℃ for 3.5h, and then perform ultrasonic exfoliation on the reaction product to obtain modified graphene with an aspect ratio of 420, an oxygen content of 3.3at%, an alkoxysilane grafting rate of 13wt%, and a number of layers of 4.

[0062] (2) Dissolve 3g of the above modified graphene, 50g of polyurethane resin, 1.5g of BYK-163 dispersant and 14g of mica iron oxide in 20ml of a mixed solvent of xylene and butanol (wherein the volume ratio of xylene to butanol is 7:3), mix and shear at 2000rpm for 1.5h, then add 14.7g of toluene diisocyanate curing agent to the mixture and mix evenly to obtain the anti-corrosion polyurethane coating with a viscosity of 55s in ISO cup.

[0063] Example 2

[0064] The only difference between the preparation method of the anti-corrosion polyurethane coating in Example 2 and that in Example 1 is that the amount of polyurethane resin and modified graphene added during the preparation of the anti-corrosion polyurethane coating in Example 2 is different from that in Example 1.

[0065] The specific operating steps include dissolving 1.5g of the modified graphene, 50g of polyurethane resin, 1.5g of BYK-163 dispersant, and 14g of mica iron oxide in 20ml of a mixed solvent of xylene and butanol (wherein the volume ratio of xylene to butanol is 7:3), mixing and shearing at 2000rpm for 1.5h, and then adding 13.2g of toluene diisocyanate curing agent to the mixture and mixing evenly to obtain the anti-corrosion polyurethane coating with a viscosity of 55s in an ISO cup.

[0066] Example 3

[0067] The only difference between the preparation method of the anti-corrosion polyurethane coating in Example 3 and that in Example 1 is that the amount of polyurethane resin and modified graphene added during the preparation of the anti-corrosion polyurethane coating in Example 3 is different from that in Example 1.

[0068] The specific operating steps include dissolving 0.5g of the modified graphene, 50g of polyurethane resin, 1.5g of BYK-163 dispersant, and 14g of mica iron oxide in 22ml of a mixed solvent of xylene and butanol (wherein the volume ratio of xylene to butanol is 7:3), mixing and shearing at 2000rpm for 1.5h, and then adding 17g of toluene diisocyanate curing agent to the mixture and mixing evenly to obtain the anti-corrosion polyurethane coating with a viscosity of 55s in an ISO cup.

[0069] Example 4

[0070] The only difference between the preparation method of the anti-corrosion polyurethane coating in Example 4 and that in Example 1 is that the amount of polyurethane resin and modified graphene added in the preparation process of the anti-corrosion polyurethane coating in Example 3 is different from that in Example 1.

[0071] The specific operating steps include dissolving 6g of the modified graphene, 50g of polyurethane resin, 1.5g of BYK-163 dispersant, and 14g of mica iron oxide in 19ml of a mixed solvent of xylene and butanol (wherein the volume ratio of xylene to butanol is 7:3), mixing and shearing at 2000rpm for 1.5h, and then adding 12.5g of toluene diisocyanate curing agent to the mixture and mixing evenly to obtain the anti-corrosion polyurethane coating with a viscosity of 55s in an ISO cup.

[0072] Example 5

[0073] The only difference between the preparation method of the anti-corrosion polyurethane coating in Example 5 and that in Example 1 is that the aspect ratio of the modified graphene in the preparation process of the anti-corrosion polyurethane coating in Example 4 is 260.

[0074] Comparative Example 1

[0075] The only difference between the preparation method of the anti-corrosion polyurethane coating in Comparative Example 1 and Example 1 is that the number of modified graphene layers in the preparation process of the anti-corrosion polyurethane coating in Comparative Example 1 is 8.

[0076] Comparative Example 2

[0077] The only difference between the preparation method of the anti-corrosion polyurethane coating in Comparative Example 2 and Example 1 is that the aspect ratio of the modified graphene in the preparation process of the anti-corrosion polyurethane coating in Comparative Example 2 is 200.

[0078] Comparative Example 3

[0079] The only difference between the preparation method of the anti-corrosion polyurethane coating in Comparative Example 3 and Example 1 is that graphene is used instead of modified graphene in the preparation process of the anti-corrosion polyurethane coating in Comparative Example 3.

[0080] Comparative Example 4

[0081] The only difference between the preparation method of the anti-corrosion polyurethane coating in Comparative Example 4 and Example 1 is that carbon nanotubes are used instead of modified graphene in the preparation process of the anti-corrosion polyurethane coating in Comparative Example 4.

[0082] Comparative Example 5

[0083] The only difference between the preparation method of the anti-corrosion polyurethane coating in Comparative Example 5 and Example 1 is that glass flakes are used instead of modified graphene in the preparation process of the anti-corrosion polyurethane coating in Comparative Example 5.

[0084] Performance Study of Anticorrosive Polyurethane Coatings Obtained by the Preparation Methods of Any One of Examples 1-5 and Comparative Examples 1-5 of this Application

[0085] The anti-corrosion polyurethane coatings obtained by the preparation methods described in Examples 1-5 and Comparative Examples 1-5 of this application were respectively applied to Q235 steel plates and cured at 25°C for 7 days to obtain coatings with a thickness of 85 μm.

[0086] The corrosion resistance, adhesion, impact strength, water vapor transmission rate and gloss of each coating were tested, and the results are shown in Table 1.

[0087] Note: The corrosion resistance test method is based on ISO 9227;

[0088] The adhesion test method is in accordance with GB / T 5210;

[0089] The test method for impact strength is based on GB / T 1732;

[0090] The test method for water vapor transmission rate is based on ASTM E96;

[0091] The test method for gloss at 60℃ is based on GB / T 9754.

[0092] Table 1

[0093]

[0094]

[0095] As can be seen from Table 1, the anti-corrosion polyurethane coating described in this application has good anti-corrosion performance and mechanical properties, and strong adhesion.

[0096] Comparative examples 1-4 show that when the mass ratio of modified graphene to polyurethane resin in the anti-corrosion polyurethane coating is (0.5-3):50, the resulting anti-corrosion polyurethane coating has higher anti-corrosion performance, adhesion, and impact resistance.

[0097] Comparing Example 1 and Comparative Example 1, it can be seen that the anti-corrosion polyurethane coating prepared using graphene with a smaller number of layers has higher anti-corrosion performance, adhesion and impact resistance.

[0098] Comparing Example 1, Example 5 and Comparative Example 2, it can be seen that when the aspect ratio of modified graphene is ≥240:1, the obtained anti-corrosion polyurethane coating has higher anti-corrosion performance, adhesion and impact resistance.

[0099] Comparing Example 1 and Comparative Examples 3-5, it can be seen that the anti-corrosion polyurethane coating prepared using the modified graphene described in this application has higher anti-corrosion performance, adhesion, and impact resistance.

[0100] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A corrosion-resistant polyurethane coating, characterized in that, It includes polyurethane resin, modified graphene, curing agent, and solvent; The modified graphene has alkoxysilane grafted onto its surface, and the number of layers in the modified graphene is ≤4.

2. The anti-corrosion polyurethane coating according to claim 1, characterized in that, The raw materials include the following parts by weight: 30-55 parts polyurethane resin, 0.5-6 parts modified graphene, 12-24 parts curing agent, and 12-30 parts solvent.

3. The anti-corrosion polyurethane coating according to claim 1, characterized in that, The modified graphene has an aspect ratio ≥ 240:1; And / or, the oxygen content of the modified graphene is ≤4.5 at%.

4. The anti-corrosion polyurethane coating according to claim 1, characterized in that, The grafting rate of alkoxysilane on the modified graphene is 5-15 wt%.

5. The anti-corrosion polyurethane coating according to claim 1, characterized in that, The alkoxysilanes include γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane; And / or, the curing agent includes a polyisocyanate curing agent; And / or, the solvent includes xylene and / or butanol.

6. The anti-corrosion polyurethane coating according to claim 1, characterized in that, It also includes 1-5 parts of additives and 6-15 parts of preservative pigments; Preferably, the additive includes a dispersant; more preferably, the dispersant includes BYK-163 dispersant. Preferably, the anti-corrosion pigment includes one or more of ferrophosphorus powder, ferric oxide mica, and zinc chromium yellow.

7. The method for preparing the anti-corrosion polyurethane coating according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of modified graphene: (2) The modified graphene, polyurethane resin, curing agent, solvent, optional additives and anti-corrosion pigments are mixed to obtain the anti-corrosion polyurethane coating.

8. The method for preparing the anti-corrosion polyurethane coating according to claim 7, characterized in that, The method for preparing the modified graphene includes the following steps: a. Mix graphene oxide and hydrazine hydrate and carry out a reduction reaction to obtain reduced graphene oxide; b. Mix the reduced graphene oxide and alkoxysilane and carry out an esterification reaction; c. The esterification reaction product is subjected to ultrasonic exfoliation to obtain the modified graphene.

9. The method for preparing the anti-corrosion polyurethane coating according to claim 8, characterized in that, The esterification reaction is carried out at a temperature of 60-80℃ for 2-4 hours.

10. The application of the anti-corrosion polyurethane coating according to any one of claims 1-6 or the anti-corrosion polyurethane coating obtained by the preparation method according to any one of claims 7-9 in the corrosion protection of metal substrates; Preferably, the metal substrate includes offshore wind power equipment, oil pipelines, or bridge equipment.

Images