Cathodic disbonding resistant coating and preparation method thereof

Abstract

The invention relates to a cathodic disbonding resistant coating which comprises a component A and a component B. The mass ratio of the component A to the component B is 20: (3-5). The component A comprises the following components in parts by weight: 25-31 parts of bisphenol A epoxy resin; 4-5 parts of a reactive diluent; 0.5 to 1.5 parts of an anti-sagging auxiliary agent; 0.3 to 0.8 part of a dispersant; 8 to 12 parts of titanium dioxide; 2-5 parts of iron oxide red; 5-8 parts of an anti-rust pigment; 2-3 parts of polyamide wax; 28-37 parts of a functional filler; the component B is phenolic aldehyde amine resin; the cathodic disbonding resistant coating disclosed by the invention is simple in preparation method, excellent in corrosion resistance, capable of being thickly coated and suitable for a long-term application environment.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a cathode stripping resistant coating and a preparation method thereof. Background Art

[0002] Cathodic disbonding is a common form of damage to coated metals, and usually occurs on equipment that uses cathodic protection, such as ships, offshore platforms, underground pipelines, etc. Cathodic protection is an effective anti-corrosion technology, but in some cases, if the cathodic protection is not ideal, it may lead to a decrease in adhesion between the coating and the metal surface, and the coating will separate from the metal. This phenomenon is called cathodic disbonding. During the cathodic protection process, the metal surface may become a cathodic area, catalyzing the cathodic reaction under the coating. This cathodic nature can be induced by cathodic polarization in cathodic protection or by corrosion. The mechanism of cathodic disbonding is quite complex and varies with different coating systems. There are currently three main proposed cathodic disbonding mechanisms, all of which are related to the high pH value produced by the cathode oxygen absorption reaction:

[0003] (1) The coating separates at the interface, that is, the adhesion of the coating is destroyed, or the interface is replaced by water, causing the coating to separate from the metal surface.

[0004] (2) The oxide on the metal is dissolved, and the alkaline substances produced by the cathode reaction dissolve the oxide film on the metal, destroying the bond between the coating and the substrate, resulting in peeling.

[0005] (3) The cohesion of the coating is destroyed and depolymerized, and the physical and chemical structure of the coating itself is damaged, which affects the bonding strength between the coating and the metal interface.

[0006] In marine engineering, cathodic protection is an effective means to prevent metal corrosion in seawater, sea mud and concrete. Cathodic protection technology includes two methods: sacrificial anode and impressed current cathodic protection. The sacrificial anode method is simple and reliable, and does not require daily maintenance, while impressed current cathodic protection can achieve automatic control. By automatically adjusting the output current, the surface of the protected structure is within the set protection potential range. In the cathodic protection of buried pipelines, various thin liquid environments with near-neutral to high pH values ​​may appear under the stripping coating. High cathodic protection current can produce and maintain a high pH environment on the pipe surface, while large-area stripping, cathodic protection shielding or loss, and the buffering effect of CO2 may lead to the sealing of a near-neutral pH stress corrosion cracking sensitive thin liquid environment under the stripping coating. By measuring the pH value of the gap thin liquid under the stripping coating, the effectiveness of cathodic protection under the stripping coating and its shielding degree can be judged.

[0007] In order to improve the anti-cathode stripping performance of the coating, it can be achieved by improving the alkaline medium resistance of the coating and improving the adhesion between the coating and the base metal. The existing anti-cathode stripping coatings are mainly divided into organic solvent-based and water-based. Most of the organic solvent-based anti-cathode stripping coatings are composed of two or more high molecular weight epoxy resin compositions as film-forming substances, and various additives are added. Chinese patent CN104371506 A discloses a two-component organic solvent-based anti-cathode stripping coating made of bisphenol F liquid epoxy resin, bisphenol A liquid epoxy resin, glycidyl ether epoxy resin, epoxy linseed oil, silane coupling agent, additives, etc. The coating has good resistance to seawater immersion, but does not consider the coating's anti-cathode stripping performance at room temperature and has the disadvantage of complex components; Patent CN 106398461 A discloses a water-based anti-cathode stripping epoxy coating, which adds water-based dimer acid-modified epoxy resin, and the cured product has good flexibility, but the water-based coating has poor anti-corrosion performance, which is far lower than that of solvent-based coating products, and is difficult to adapt to environments such as ballast tanks with complex working conditions and long-term protection. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention proposes a cathode stripping resistant coating and a preparation method thereof. The coating preparation method is simple, has excellent anti-corrosion ability, can be thickly coated, and is suitable for long-term application environments.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention provides a cathode stripping resistant coating, which comprises a component A and a component B, wherein the mass ratio of the component A to the component B is 20:3-5;

[0011] The component A comprises the following components in parts by weight:

[0012]

[0013] The component B is a phenolic amine resin.

[0014] Preferably, the model of the bisphenol A epoxy resin is E51.

[0015] Preferably, the model of the active diluent is 692.

[0016] Preferably, the polyamide wax has a model of DeuRheo 229.

[0017] Preferably, the anti-sagging agent is BYK410 anti-sagging agent.

[0018] Preferably, the dispersant is BYK110 dispersant.

[0019] Preferably, the titanium dioxide is R818 rutile titanium dioxide, the particle size of the powder is less than 800 mesh, and the particle size of the red iron oxide is less than 500 mesh.

[0020] Preferably, the anti-rust pigment is aluminum tripolyphosphate powder with a particle size of less than 800 meshes, and the functional filler is a floating flaky aluminum powder slurry with a particle size of 80 meshes.

[0021] Preferably, the phenalkamine resin model is nx-5594.

[0022] The present invention also provides a method for preparing a cathode stripping resistant coating, comprising the following steps:

[0023] S1. Add the active diluent to the bisphenol A epoxy resin, disperse it at a speed of 1000-1500 r / min for 30-40 minutes, mix it evenly, and obtain a resin dilution;

[0024] S2. Add anti-sagging agent, dispersant and polyamide wax to the resin dilution in sequence, disperse at a speed of 2000-2200 r / min for 15-20 minutes, mix evenly, and obtain slurry;

[0025] S3, add titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, disperse at a speed of 1000-1200 r / min for 30-40 minutes, mix evenly, and obtain component A;

[0026] S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The cathode stripping resistant coating of the present invention is a two-component coating composed of a cross-linked product of epoxy resin and phenolic amine resin as a skeleton, and various functional additives and powders are added. The preparation process is simple, thick coating can be applied, and the drying speed is fast at low temperature. The phenolic hydroxyl group introduced into the phenolic amine resin structure can promote the reaction activity of the cured product and reduce the curing temperature of the epoxy resin. The reactive epoxy group contained in the active diluent directly participates in the reaction. The two work together to ensure the low-temperature drying speed of the system. The anti-sagging additive and polyamide wax can form a three-dimensional network structure inside the coating by hydrogen bonding, etc., improve the thixotropy of the system, reduce sagging, and facilitate thick coating operations. The dispersant is adsorbed on the surface of the pigment and filler, which can improve wetting and enhance the stability of the system.

[0029] (2) The cathode stripping-resistant coating of the present invention has excellent adhesion to the substrate (adhesion is higher than 15MPa) and good flexibility, and excellent cathode stripping resistance. The stripping radius of the 180d test at room temperature is less than 1mm. The epoxy resin contains a large number of polar functional groups such as hydroxyl groups, which provides the cured product with good adhesion to the substrate; the reaction product of the active diluent and the phenolic amine resin is interspersed in the cured paint film, which is beneficial to improve flexibility; the red iron oxide and the functional filler aluminum powder are both flaky at the microscopic level, forming a "maze effect", which effectively prolongs the time for the corrosive medium to penetrate into the substrate. In the case of a difference in corrosion potential, the aluminum powder can be used as a sacrificial anode to protect the substrate, prevent local corrosion, and thus improve the cathode stripping resistance.

[0030] (3) The cathodic stripping resistant coating of the present invention has excellent anti-corrosion performance and can be adapted to long-term anti-corrosion environments such as ballast tanks. The film-forming material is a low molecular weight resin with a high degree of reaction crosslinking. The added anti-rust pigment is a slow-release type and can form an inert protective layer on the metal surface. The flaky filler can effectively prevent chloride ions and seawater from penetrating, greatly improving the anti-corrosion ability of the system. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A cathode stripping resistant coating comprises the following components in parts by weight: 25 parts of bisphenol A epoxy resin, 4 parts of active diluent, 0.5 parts of anti-sagging agent, 0.8 parts of dispersant, 8 parts of titanium dioxide, 5 parts of red iron oxide, 5 parts of anti-rust pigment, 2.7 parts of polyamide wax, 37 parts of leafing flaky aluminum powder slurry; and 13.2 parts of phenolic amine resin.

[0034] The preparation method of the cathode stripping resistant coating in this embodiment is as follows:

[0035] S1, adding the active diluent to the bisphenol A epoxy resin, dispersing at a speed of 1000r / min for 30 minutes, mixing evenly, and obtaining a resin dilution;

[0036] S2, add anti-sagging aid, dispersant and polyamide wax to the resin dilution in sequence, disperse at a speed of 2100r / min for 15 minutes, mix evenly, and obtain slurry;

[0037] S3, add titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, disperse at a speed of 1000 r / min for 30 minutes, mix evenly, and obtain component A;

[0038] S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

[0039] Example 2

[0040] A cathode stripping resistant coating comprises the following components in parts by weight: 25 parts of bisphenol A epoxy resin, 4 parts of active diluent, 0.7 parts of anti-sagging agent, 0.8 parts of dispersant, 8 parts of titanium dioxide, 3 parts of red iron oxide, 8 parts of rust-proof pigment, 2.5 parts of polyamide wax, 30 parts of leafing flaky aluminum powder slurry and 14.3 parts of phenolic amine resin.

[0041] The preparation method of the cathode stripping resistant coating in this embodiment is as follows:

[0042] S1, adding the active diluent to the bisphenol A epoxy resin, dispersing at a speed of 1100 r / min for 40 minutes, mixing evenly, to obtain a resin dilution;

[0043] S2, adding an anti-sagging aid, a dispersant and a polyamide wax to the resin dilution in sequence, dispersing at a speed of 2000 r / min for 20 minutes, mixing evenly, and obtaining a slurry;

[0044] S3, add titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, disperse at a speed of 1200 r / min for 35 minutes, mix evenly, and obtain component A;

[0045] S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

[0046] Example 3

[0047] A cathode stripping resistant coating comprises the following components in parts by weight: 28 parts of bisphenol A epoxy resin, 4.5 parts of active diluent, 1 part of anti-sagging agent, 0.5 parts of dispersant, 10 parts of titanium dioxide, 2 parts of red iron oxide, 7 parts of rust-proof pigment, 2.5 parts of polyamide wax, 28 parts of leafing flaky aluminum powder slurry and 16.7 parts of phenolic amine resin.

[0048] The preparation method of the cathode stripping resistant coating in this embodiment is as follows:

[0049] S1, adding the active diluent to the bisphenol A epoxy resin, dispersing at a speed of 1300r / min for 35 minutes, mixing evenly, to obtain a resin dilution;

[0050] S2, adding an anti-sagging agent, a dispersant and a polyamide wax to the resin dilution in sequence, dispersing at a speed of 2100 r / min for 17 minutes, mixing evenly, and obtaining a slurry;

[0051] S3, add titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, disperse at a speed of 1100 r / min for 40 minutes, mix evenly, and obtain component A;

[0052] S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

[0053] Example 4

[0054] A cathode stripping resistant coating comprises the following components in parts by weight: 31 parts of bisphenol A epoxy resin, 5 parts of active diluent, 1.3 parts of anti-sagging agent, 0.3 parts of dispersant, 10 parts of titanium dioxide, 5 parts of red iron oxide, 7 parts of rust-proof pigment, 2.4 parts of polyamide wax, 30 parts of leafing flaky aluminum powder slurry and 20.7 parts of phenolic amine resin.

[0055] The preparation method of the cathode stripping resistant coating in this embodiment is as follows:

[0056] S1, adding the active diluent to the bisphenol A epoxy resin, dispersing at a speed of 1500r / min for 35 minutes, mixing evenly, to obtain a resin dilution;

[0057] S2, adding an anti-sagging aid, a dispersant and a polyamide wax to the resin dilution in sequence, dispersing at a speed of 2000 r / min for 18 minutes, mixing evenly, and obtaining a slurry;

[0058] S3, add titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, disperse at a speed of 1000 r / min for 35 minutes, mix evenly, and obtain component A;

[0059] S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

[0060] Example 5

[0061] A cathode stripping resistant coating comprises the following components in parts by weight: 31 parts of bisphenol A epoxy resin, 5 parts of active diluent, 1.5 parts of anti-sagging agent, 0.5 parts of dispersant, 12 parts of titanium dioxide, 2 parts of red iron oxide, 8 parts of rust-proof pigment, 2 parts of polyamide wax, 28 parts of leafing flaky aluminum powder slurry and 23.7 parts of phenolic amine resin.

[0062] The preparation method of the cathode stripping resistant coating in this embodiment is as follows:

[0063] S1, adding the active diluent to the bisphenol A epoxy resin, dispersing at a speed of 1500r / min for 40 minutes, mixing evenly, to obtain a resin dilution;

[0064] S2, adding an anti-sagging aid, a dispersant and a polyamide wax to the resin dilution in sequence, dispersing at a speed of 2200 r / min for 20 minutes, mixing evenly, and obtaining a slurry;

[0065] S3, adding titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, dispersing at a speed of 1200 r / min for 40 minutes, and mixing evenly to obtain component A;

[0066] S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

[0067] In the above embodiments, the epoxy resin is of type E51, has an epoxy value of 0.51 mol / 100 g, is a colorless, transparent, viscous fluid at room temperature, and is preferably sourced from Jiangsu Sanmu Chemical Co., Ltd.;

[0068] The active diluent model is 692, the main component is benzyl glycidyl ether, it is liquid at room temperature, and is preferably sourced from Hemingsdeqian (Shanghai) Chemical Co., Ltd.;

[0069] The polyamide wax model is DeuRheo 229, and its appearance is slightly yellow soft wax, and it is preferably sourced from Hemmings Deqian (Shanghai) Chemical Co., Ltd.

[0070] The anti-sagging agent is BYK410 anti-sagging agent, which is a colorless liquid at room temperature and is preferably sourced from BYK Additives (Shanghai) Co., Ltd.

[0071] The dispersant is BYK110 dispersant, which is a colorless liquid at room temperature and is preferably sourced from BYK Additives (Shanghai) Co., Ltd.

[0072] The titanium dioxide is R818 rutile titanium dioxide, the particle size of the powder is less than 800 mesh, and the particle size of the red iron oxide is less than 500 mesh, preferably sourced from Jie De Industry and Trade Co., Ltd.

[0073] The anti-rust pigment is aluminum tripolyphosphate powder, the particle size of which is less than 800 meshes, and is preferably sourced from Shanghai BASF Chemical Company.

[0074] The functional filler is a floating flake aluminum powder slurry with a particle size of 80 mesh, preferably sourced from Changsha Zuxing Aluminum Pigment Company.

[0075] The phenolic amine resin model is nx-5594, which is a dark yellow liquid at room temperature, with an amine value of 390-420 (mg KOH / g), and is preferably sourced from Cardolite Chemical (Zhuhai) Co., Ltd.

[0076] In order to better understand the excellent performance of the present invention, the cathodic disbonding resistant coatings prepared in Examples 1 to 5 were coated on the surface of the steel plate, and the cathodic disbonding resistance of the coatings was tested according to GB / T7790-2008 "Determination of cathodic disbonding resistance of coatings of paints and varnishes exposed to seawater", the coating adhesion was tested according to GB / T 5210-2006 "Paint and varnish adhesion test by pull-off method", and the salt spray resistance of the coating was tested according to GB / T 1771-2007 "Determination of neutral salt spray resistance of paints and varnishes". The coating parameters of each embodiment are shown in Table 1, and the performance test results are shown in Table 2:

[0077] Table 1 Coating process parameters

[0078]

[0079]

[0080] Table 2 Performance test results

[0081]

[0082] It can be seen from Table 2 that the cathode stripping resistance prepared by the present invention is excellent, the adhesion advantage is obvious, and the salt spray resistance reaches 2000h, which fully meets the requirements.

[0083] In the present invention, the active diluent, anti-sagging aid and dispersant may be other products on the market that meet the requirements in addition to those mentioned in the examples, but the products used in the above examples have better effects.

[0084] The specific embodiments of the present invention enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0085] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A cathodic stripping resistant coating, characterized in that: The cathodic stripping resistant coating comprises component A and component B, wherein the mass ratio of component A to component B is 20:3-5; The component A comprises the following components in parts by weight: The component B is a phenolic amine resin.

2. The cathodic disbonding resistant coating according to claim 1, characterized in that: The model of the bisphenol A epoxy resin is E51.

3. The cathodic disbonding resistant coating according to claim 1, characterized in that: The model of the active diluent is 692.

4. The cathodic disbonding resistant coating according to claim 1, characterized in that: The model of the polyamide wax is DeuRheo 229.

5. The cathodic disbonding resistant coating according to claim 1, characterized in that: The anti-sagging agent is BYK410 anti-sagging agent.

6. The cathodic disbonding resistant coating according to claim 1, characterized in that: The dispersant is BYK110 dispersant.

7. The cathodic disbonding resistant coating according to claim 1, characterized in that: The titanium dioxide is R818 rutile titanium dioxide, the particle size of the powder is less than 800 mesh, and the particle size of the red iron oxide is less than 500 mesh.

8. The cathodic disbonding resistant coating according to claim 1, characterized in that: The anti-rust pigment is aluminum tripolyphosphate powder with a particle size of less than 800 meshes, and the functional filler is a floating flaky aluminum powder slurry with a particle size of 80 meshes.

9. The cathodic disbonding resistant coating according to claim 1, characterized in that: The phenalkamine resin model is nx-5594.

10. A method for preparing a cathodic stripping resistant coating, characterized in that: The steps include: S1. Add the active diluent to the bisphenol A epoxy resin, disperse it at a speed of 1000-1500 r / min for 30-40 minutes, mix it evenly, and obtain a resin dilution; S2. Add anti-sagging agent, dispersant and polyamide wax to the resin dilution in sequence, disperse at a speed of 2000-2200 r / min for 15-20 minutes, mix evenly, and obtain slurry; S3, add titanium dioxide, red iron oxide, anti-rust pigment, and functional filler to the slurry in sequence, disperse at a speed of 1000-1200 r / min for 30-40 minutes, mix evenly, and obtain component A; S4. Evenly mix component A and phenolic amine resin to obtain a cathode stripping resistant coating.

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