High-build waterborne epoxy heavy anti-corrosion coating and preparation method thereof

Abstract

The invention discloses a high-build waterborne epoxy heavy anti-corrosion coating and a preparation method thereof. The coating is a water-based, double-component and room-temperature self-drying type product and is prepared from water-based epoxy resin, modified amine emulsion, castor oil polyglycidyl ether, pigment filler, anti-rust pigment, a cosolvent, water and a functional additive. Due to the adoption of a special amine curing system and an auxiliary material compatibility scheme, the obtained coating is high in solid content in volume, quick to dry, capable of realizing thick coating construction, resistant to chemicals, resistant to corrosion and capable of being attached to multiple base materials, and is a thick-paste water paint suitable for heavy-duty anticorrosion fields such as petrifaction, maritime work, energy, bridges and the like.

Description

Technical Field

[0001] The present invention relates to the field of coating technology, and specifically to a thick paste water-based epoxy heavy-duty anti-corrosion coating suitable for heavy-duty anti-corrosion fields such as petrochemicals, marine engineering, energy, and bridges, which has high volume solid content, fast drying, can be applied in thick layers, is chemical-resistant, corrosion-resistant, and can adhere to multiple substrates, and a preparation method thereof. Background Art

[0002] Heavy-duty anti-corrosion coatings mainly refer to a type of coating material that can protect substrates (metals, concrete, etc.) from erosion by high temperature, high humidity, high salt, corrosive gases, chemicals, etc. for a long time in harsh environments. They are widely used in key infrastructure such as petrochemicals (such as storage tanks and pipelines), marine engineering (such as offshore drilling platforms and port facilities), energy (such as thermal power and nuclear power), and bridges.

[0003] Traditional heavy-duty anti-corrosion coatings are mainly solvent-based products (such as solvent-based epoxy coatings, solvent-based polyurethane coatings, solvent-based fluororesin coatings, solvent-based silicone resin coatings, solvent-based unsaturated polyester coatings, etc.), with organic solvents such as xylene, butyl acetate, cyclohexanone, and styrene as dispersion media. Therefore, this type of product has significant VOC emissions during the construction process, and there are safety and health risks such as flammability, explosiveness, respiratory irritation, and biological toxicity. In the current era of emission reduction and carbon reduction, traditional heavy-duty anti-corrosion coatings are in urgent need of environmentally friendly upgrades. Epoxy coatings are an important research direction for the transformation of heavy-duty anti-corrosion coatings to water-based ones because of their excellent adhesion and electrical insulation, good corrosion resistance, mechanical strength, and chemical resistance.

[0004] At present, waterborne epoxy coating technology has been iterated many times, and common waterborne strategies are:

[0005] (1) Use solvent-based liquid epoxy resin with a water-soluble amine curing agent with emulsifying activity. This system is simple to prepare and low-cost, but its defects are also obvious. The main problems are: the mixing operation requirements of epoxy resin and curing agent are high, the viscosity of the system is high at the initial stage of mixed phase transition, and improper mixing and emulsification will directly affect the performance and appearance of the coating; the coating has a short application period, and the operable period is usually only 0.5 to 1.5 hours; the curing agent is too hydrophilic and the overall anti-corrosion performance is poor; the initial film-forming material has a low molecular weight and the coating strength is poor; the coating cross-linking degree in the later stage is too high, the coating is brittle, and toughening modification is required.

[0006] (2) Use mechanically emulsified solid epoxy resin with a hydrophobic amine adduct curing agent. The main defects of this system are: the epoxy emulsion has a large particle size, wide distribution, and poor stability; the free emulsifier is easy to migrate, affecting the water resistance of the coating; after curing, the coating has poor density and low comprehensive corrosion resistance; the curing agent requires alcohol or ether solvents to have good dispersibility and compatibility; it is not easy to obtain a highly decorative coating appearance.

[0007] (3) Grafting nonionic surfactant chains into the molecular structure of epoxy resin and amine curing agent to achieve self-emulsification of the film-forming material. This technical route can significantly reduce the impact of free surfactants on coating performance, reduce the emulsified particle size of the film-forming material, improve system stability, and improve the density and appearance of the coating. Its disadvantages are: the preparation process is complex and the cost is slightly high; the composition and ratio of the grafted components must be strictly screened, otherwise a coating with a high degree of cross-linking cannot be obtained; and the balance between reaction activity and pot life.

[0008] Among them, the coating solution based on graft modification has the greatest development potential. Public data shows that the salt spray resistance of this type of anti-corrosion coating (referring only to non-zinc-rich epoxy coatings) has reached 300 to 600 hours (100μm, single coating), and has the prospect of heavy-duty anti-corrosion application. However, due to the dryness and hydrophilicity defects caused by the introduction of water media, its heavy-duty anti-corrosion products still have many shortcomings that need to be addressed urgently. The main defects are as follows:

[0009] (1) Low volume solid content of the coating: A thick film cannot be obtained in a single application, and the overall coating cost is high; (2) Slow drying: The drying speed of the coating is difficult to guarantee under thick coating conditions, and it is more likely to produce residual moisture in extreme weather, resulting in defects such as whitening, stickiness, and inability to solidify; (3) Thick coating is prone to cracking and flash rusting: A single application of too thick a thickness makes it difficult to effectively release the stress inside the coating, and at the same time, the water is not completely discharged, which will greatly increase the risk of cracking of the coating and flash rusting of the substrate; (4) Unstable adhesion: On the one hand, the internal stress generated by thick coating conditions may cause the coating adhesion to decrease; on the other hand, water-based coatings cannot adapt to substrate conditions with low surface treatment (such as: oil, dust, rust, etc.). (5) Problems with chemical media resistance: The water-based resin often introduces high-polarity channels into the anti-corrosion coating, reducing the medium shielding efficiency of the coating. In addition, the long-term application data accumulation of water-based coatings in extreme environments is not sufficient and needs further verification and improvement. (6) The balance between cost and performance: Compared with traditional solvent-based coatings, the cost of water-based solutions is still relatively high, which to some extent restricts its promotion in the field of heavy corrosion protection. Summary of the Invention

[0010] The purpose of the present invention is to provide a thick paste type waterborne epoxy heavy-duty anti-corrosion coating with high volume solid content, fast drying, thick coating construction, chemical resistance, corrosion resistance, and multi-substrate adhesion, and a preparation method thereof.

[0011] The purpose of the present invention can be achieved through the following technical solutions:

[0012] A thick build waterborne epoxy heavy-duty anti-corrosion coating, comprising component A and component B in a mass ratio of (1-15):1:

[0013] Component A consists of the following ingredients by mass:

[0014]

[0015]

[0016] Component B consists of the following ingredients by mass:

[0017] 3-8 parts of anti-flash rust additive

[0018] 1-3 parts wax rheological additive

[0019] 90-95 parts of modified amine emulsion.

[0020] In some preferred technical solutions, the coating is composed of component A and component B in a mass ratio of (5-9):1: component A is composed of the following ingredients by mass:

[0021]

[0022]

[0023] Component B consists of the following ingredients by mass:

[0024] 3-8 parts of anti-flash rust additive

[0025] 1-3 parts wax rheological additive

[0026] 90-95 parts of modified amine emulsion.

[0027] In the technical solution of the present invention: the water-based epoxy resin is one or more of EPIKOTE 7520-WD-52A of Hexion, BECKOPOX EP 384w / 53WAMP of Allnex Chemical, or STW 606 of Huayi Fine Chemical; and the castor oil polyglycidyl ether is HEXION HELOXY 505 of Hexion.

[0028] In the technical solution of the present invention, the coloring pigment is one or more of rutile titanium dioxide, pigment red 170, pigment red 254, pigment yellow 154, pigment yellow 83, pigment yellow 151, phthalocyanine blue, phthalocyanine green, carbon black and iron oxide red.

[0029] In the technical solution of the present invention: the anti-rust pigment is a mixture of HEUCOPHOS ZPA aluminum zinc orthophosphate hydrate, Xinjing Technology APW-II zinc oxide modified aluminum tripolyphosphate and Junjiang Technology JP-B803 inorganic high-efficiency corrosion inhibitor, and the mass ratio of the three is (3~7): (1~4): 0.5~1.

[0030] In the technical solution of the present invention: the average particle size of the sericite powder is 10 to 20 μm; the median particle size of the hollow glass microspheres is 20 to 30 μm, preferably: 3M iM16K, S32HS or S28HS hollow glass microspheres; the water-based aluminum-silver paste is a silica-coated passivated aluminum powder paste with an average particle size of 15 to 35 μm, preferably: the water-based aluminum-silver paste is SILBERCOTE AQ ELITE 015LM, SILBERCOTE AQ ULTRA020LM of Star Platinum or Hefei Xuyang WHD8008A, Hefei Xuyang WHD8214, Hefei Xuyang WHD8221.

[0031] In the technical solution of the present invention: the wetting and dispersing agent is Digo Dispers 757W; the defoaming agent is Digo Foamex 810; the substrate wetting agent is Digo Wet KL 245; the polyurethane thickener is Ashland AQUAFLOW XLS-525; the anti-flash rust additive is Enze Chemical HY78; and the wax rheological additive is BYK AQUATIX 8421.

[0032] In the technical solution of the present invention: the solid content of the modified amine emulsion is 45-55wt%, the active hydrogen equivalent is 370-500g / mol; the molar ratio of the epoxy group in component A to the active hydrogen in component B is 1:(0.82-0.93);

[0033] Preferably, the modified amine emulsion is prepared by the following steps:

[0034] S1: Add toluene, polyethylene glycol monomethyl ether glycidyl ether and 4,4'-diaminodicyclohexylmethane into a reaction kettle, raise the temperature to 80-110°C, and stir to react for 1-2 hours;

[0035] S2: Add benzyl glycidyl ether and continue the reaction for 0.5 to 1 hour;

[0036] S3: First add m-xylenediamine, then slowly add a mixed solution of E51 epoxy resin, glycidyl butyl ether, γ-glycidyloxypropyltrimethoxysilane and toluene. After the addition is complete, keep the mixture at 100-120°C for 0.1-1h, and finally add 2,4,6-tris(dimethylaminomethyl)phenol and stir to mix evenly;

[0037] S4: Remove toluene under reduced pressure and cool to 60-90°C. Slowly add water into the reactor under high-speed stirring. Continue to disperse for 20-40 minutes after addition. Cool and filter to obtain a modified amine emulsion.

[0038] Preferably, the specific amount of each component in the preparation method of the modified amine emulsion is as follows:

[0039]

[0040] Preferably, the polyethylene glycol monomethyl ether glycidyl ether is purchased from Shi Neng, and the model is MPEG-EPO.

[0041] A method for preparing the above-mentioned high-build waterborne epoxy heavy-duty anti-corrosion coating comprises the following steps:

[0042] S1: Add water and a wetting and dispersing agent to a paint mixing kettle and stir evenly. Add coloring pigment, anti-rust pigment, fumed silica, and defoamer, and disperse at high speed until there are no lumps or agglomerates. Transfer the slurry to a sand mill and grind to a fineness of less than 40 μm. Add water-based epoxy resin, castor oil polyglycidyl ether, dipropylene glycol butyl ether, ethanol, a substrate wetting agent, feldspar powder, sericite powder, hollow glass microspheres, a water-based aluminum-silver paste, and an isothiazolinone fungicide to the ground slurry in sequence, stirring and dispersing until the material fineness is less than 80 μm. Add a polyurethane thickener and adjust the system viscosity to 80-120 KU (Stormer viscometer). Filter to obtain component A.

[0043] S2: Add the modified amine emulsion to a paint mixing kettle, add an anti-flash rust agent and a wax rheology additive, and stir evenly. Filter to obtain component B.

[0044] S3: Mix component A and component B evenly, add water to dilute, and obtain a thick paste type waterborne epoxy heavy anti-corrosion coating.

[0045] The thick build waterborne epoxy heavy-duty anti-corrosion coating disclosed in the present invention has the following technical advantages:

[0046] (1) Emulsion-type amine curing system with excellent performance: 4,4'-diaminodicyclohexylmethane-epoxy adduct and m-phenylenediamine-epoxy adduct with high toughness and high cross-linking activity are selected as the main curing agent, and the reactive "polyethylene glycol monomethyl ether glycidyl ether, 4,4'-diaminodicyclohexylmethane, benzyl glycidyl ether" addition product is selected as the self-emulsifying system. At the same time, two modified components, γ-glycidyl ether oxypropyl trimethoxysilane and 2,4,6-tris(dimethylaminomethyl)phenol, are added to further enhance the cross-linking activity and bonding strength of the coating. Compared with the traditional water-soluble amine curing system, the emulsion-type curing system disclosed in the present invention has many advantages such as low co-solvent demand, easy mixing, no damage to the original rheological properties of the coating (such as pseudoplasticity), fast drying, moderate hydrophilicity, etc., which is very suitable for thick film coating.

[0047] (2) Lightweight filler combination with high shielding properties: A powder combination of "lightweight filler (hollow glass microspheres) + flaky shielding filler (aluminum powder, sericite) + inert filler (feldspar powder)" is selected to reduce the dry film density of the anti-corrosion coating to 1.2g / cm while ensuring the shielding performance and cohesive strength of the coating. 3 The following is to more conveniently obtain a dense and thick coating.

[0048] (3) Excellent anti-rust pigment combination scheme: The anti-rust pigment combination scheme of "aluminum zinc orthophosphate hydrate + inorganic corrosion inhibitor + modified aluminum tripolyphosphate" is selected. Through the three different functional combinations of "initial corrosion inhibition, long-term foaming inhibition and long-term substrate passivation", a water-based long-term anti-corrosion coating with salt spray resistance of more than 1200 hours is obtained.

[0049] The thick paste water-based epoxy heavy-duty anti-corrosion coating disclosed in the present invention has the advantages of high volume solid content, fast drying, thick coating construction, chemical resistance, corrosion resistance, and adhesion to multiple substrates. It is a novel water-based heavy-duty anti-corrosion coating solution. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto:

[0051] The sources of some raw materials in the examples of the present invention are as follows:

[0052] Hexion EPIKOTE 7520-WD-52A:

[0053] https: / / www.4006787252.com / article_read_5934.html

[0054] Allnex Chemical BECKOPOX EP384w / 53WAMP:

[0055] https: / / allnex.cn / cn / product / f642509d-3838-449f-a6d5-8e13bd9d0267 / beckopox-ep-384w-53wa mp-3

[0056] Huayi Refining STW606:

[0057] https: / / www.albiz.cn / information / interviewDetails / id_330172&typeid_reptile?_kw=moju

[0058] Hexion Heloxy 505:

[0059] https: / / detail.1688.com / offer / 742271224977.html?from=ye&bizId=taizhou.1688.com&no_cache=false

[0060] HEUCOPHOS ZPA:

[0061] https: / / it.sohu.com / a / 677811348_121426765

[0062] Neocrystal APW-II:

[0063] https: / / www.xinjingst.com / products / hot-products / 2035

[0064] Junjiang Technology JP-B803:

[0065] http: / / www.junjiangtech.com / h-pd-231.html

[0066] 3M Hollow Glass Microspheres iM16K:

[0067] https: / / www.3m.com.cn / 3M / zh_CN / p / d / b40064613 /

[0068] 3M Hollow Glass Microspheres S32HS:

[0069] https: / / www.3m.com.cn / 3M / zh_CN / p / d / b5005035032 /

[0070] 3M Hollow Glass Microspheres S28HS:

[0071] https: / / www.3m.com.cn / 3M / zh_CN / p / d / b40064646 /

[0072] SILBERCOTE AQ ELITE 015LM and SILBERCOTE AQ ULTRA 020LM aluminum silver pastes: https: / / silberline.com / trade-name / silbercote-aq-liquid-metal /

[0073] Hefei Xuyang WHD8008A, WHD8214, WHD8221 aluminum silver paste:

[0074] http: / / www.ahxuyang.cn / product / 16.html

[0075] Digo Dispers 757W:

[0076] https: / / b2b.baidu.com / q / aland?q=7C067116FEFCFEBE7E1F006B7508&id=qid9162219b74808a89ee67904d97ebd404&answer=11235726590666246600&utype=2

[0077] Digo Foamex 810:

[0078] https: / / b2b.baidu.com / land?id=1d39ae52ec3087958732fbd760d4a74c10

[0079] Digo Wet KL 245:

[0080] https: / / b2b.baidu.com / land?id=ddcdea5c9ae717659dfb75875473fb9a10

[0081] Ashland Aquaflow XLS-525:

[0082] https: / / aiqicha.baidu.com / productdetail?pid=35908152249177&productId=4f5bfe60c929d06bdb3f1b4e5fc4376f

[0083] Enze Chemical HY78:

[0084] http: / / www.qdenze.com / products / fsxjhy5443.html

[0085] BYK AQUATIX 8421:

[0086] https: / / b2b.baidu.com / land?id=99694b08c9666546ce659f0fffbc023910

[0087] The preparation steps of the high build waterborne epoxy heavy duty anticorrosive coatings of Examples 1 to 3 (see Table 1 for material ratios and Table 2 for test results) are as follows:

[0088] (1) Preparation of modified amine emulsion:

[0089] Add 5 parts of toluene, 4.8 parts of polyethylene glycol monomethyl ether glycidyl ether, and 4.8 parts of 4,4'-diaminodicyclohexylmethane to a reactor, heat to 100°C, and stir for 1 hour. Add 3.75 parts of benzyl glycidyl ether and continue to react for 1 hour. Add 11.2 parts of m-xylylenediamine and stir until uniform. Slowly drip a mixture of 12 parts of E51 epoxy resin, 12.35 parts of glycidyl butyl ether, 1.1 parts of γ-glycidyloxypropyltrimethoxysilane, and 10 parts of toluene into the reactor over 0.5 hour. Then, keep the mixture at 120°C for 0.5 hour. Add 0.8 parts of 2,4,6-tris(dimethylaminomethyl)phenol and stir until uniform. Remove the toluene by vacuum distillation, and cool to 70°C. Add 44.2 parts of water dropwise to the reactor under high-speed stirring over 0.5 hour. After the addition is complete, continue dispersing for 0.5 hour. After cooling and filtering, a modified amine emulsion with a solid content of 52.6% and an active hydrogen equivalent of 413.7 g / mol was obtained. The polyethylene glycol monomethyl ether glycidyl ether was purchased from Shi Neng, with the model number being MPEG-EPO.

[0090] (2) Preparation of thick paste waterborne epoxy heavy anti-corrosion coating:

[0091] Add water and Dispers 757W wetting and dispersing agent to a paint mixing kettle and stir thoroughly. Add rutile titanium dioxide, carbon black, HEUCOPHOS ZPA aluminum zinc orthophosphate hydrate, APW-II zinc oxide-modified aluminum tripolyphosphate, JP-B803 inorganic high-efficiency corrosion inhibitor, 0.3 parts fumed silica, and 0.2 parts Foamex 810 defoamer. Disperse at high speed until there are no lumps or agglomerates. Transfer the slurry to a sand mill and grind to a fineness of less than 40 μm. To the ground slurry, water-based epoxy resin, HEXIONHELOXY 505 castor oil polyglycidyl ether, dipropylene glycol butyl ether, 4 parts ethanol, 0.2 parts Wet KL 245 substrate wetting agent, feldspar powder, sericite powder, S32HS hollow glass microspheres, WHD8008A water-based aluminum-silver paste (60 wt%), and 0.2 parts isothiazolinone fungicide were added in sequence. The mixture was stirred and dispersed until the fineness was less than 80 μm. AQUAFLOW XLS-525 polyurethane thickener was added to adjust the system viscosity to 80-120 kU (Stormer viscometer). Filtering was performed to obtain component A.

[0092] Add the modified amine emulsion to a paint mixing kettle, along with HY78 anti-flash rust agent and AQUATIX 8421 wax rheology additive, and stir until evenly combined. Filter to obtain component B.

[0093] Mix component A and component B evenly, add water to dilute, and obtain a thick paste type waterborne epoxy heavy anti-corrosion coating.

[0094] Material ratios of Comparative Examples 1 to 5 (test results are shown in Table 3):

[0095] Comparative Example 1: The "94 parts modified amine emulsion (active hydrogen equivalent of 413.7)" in component B of Example 2 was replaced with "94 parts Huntsman Aradur 3986 curing agent (active hydrogen equivalent of 415)", and the remaining material proportions were the same as in Example 2.

[0096] Comparative Example 2: The "12.35 parts of glycidyl butyl ether and 1.1 parts of γ-glycidyl ether oxypropyltrimethoxysilane" in the preparation steps of the modified amine emulsion in Example 2 were replaced by "7.50 parts of glycidyl butyl ether and 10 parts of γ-glycidyl ether oxypropyltrimethoxysilane" (the total molar number of epoxy groups remained unchanged), and the proportions of other materials were the same as in Example 2.

[0097] Comparative Example 3: The "4 parts of HEUCOPHOS ZPA aluminum zinc orthophosphate hydrate, 3 parts of APW-II zinc oxide modified aluminum tripolyphosphate, and 1 part of JP-B803 inorganic high-efficiency corrosion inhibitor" in component A of Example 2 were replaced with "8 parts of HEUCOPHOS ZPA aluminum zinc orthophosphate hydrate", and the remaining material proportions were the same as in Example 2.

[0098] Comparative Example 4: The "14 parts of feldspar powder, 8 parts of sericite powder, 5 parts of S32HS hollow glass microspheres, and 3 parts of WHD8008A water-based aluminum-silver paste (60 wt %)" in component A of Example 2 were replaced with "28.8 parts of feldspar powder" (the solid content of the powder remained unchanged), and the proportions of the remaining materials were the same as in Example 2.

[0099] Comparative Example 5: The mass ratio of component A to component B in Example 2 was changed from "6.5:1" to "5.2:1" (the molar ratio of epoxy group to active hydrogen was changed from "1:0.84" to "1:1.05"), and the remaining material ratios were the same as in Example 2.

[0100] Table 1 Material addition amount of Examples 1 to 3 (parts by mass)

[0101]

[0102]

[0103] Table 2 Main technical indicators of thick build waterborne epoxy heavy duty anticorrosive coatings of Examples 1 to 3

[0104]

[0105]

[0106] Note: The coating thickness for chemical resistance and salt spray resistance tests is 100±10μm.

[0107] Table 3 Main technical indicators of comparative examples 1 to 5 thick build waterborne epoxy heavy anticorrosive coatings

[0108]

[0109] Note: The coating thickness for chemical resistance and salt spray resistance tests is 100±10μm.

[0110] The test results show (Table 2) that Examples 1 to 3 all obtained thick-slurry water-based epoxy heavy-duty anti-corrosion coatings with high volume solid content, fast drying rate, single-application thickness of 180 to 250 μm, water resistance, acid and alkali resistance, and salt spray resistance, and can be applied to the surfaces of various metal substrates.

[0111] Among many materials, the choice of amine curing system is crucial to coating performance. This invention utilizes an emulsion-based amine curing scheme, selecting the reactive adduct of polyethylene glycol monomethyl ether glycidyl ether, 4,4'-diaminodicyclohexylmethane, and benzyl glycidyl ether as a self-emulsifier. This emulsion system effectively encapsulates the hydrophobic primary curing agent (an epoxy adduct of 4,4'-diaminodicyclohexylmethane and m-xylylenediamine), improving the compatibility of the hydrophobic amine with the epoxy emulsion while also preventing the negative impact of emulsifier migration on coating performance. Furthermore, the low cosolvent content of the emulsion-based curing system facilitates rheological adjustments. Furthermore, mixing with component A does not compromise the pseudoplastic properties of the original coating, making it suitable for thick-film application. In comparison, conventional water-soluble amine curing systems require more complex rheological design and exhibit poor anti-sagging performance. For example, in Comparative Example 1, the non-emulsion Huntsman Aradur 3986 curing agent was used in place of the modified amine emulsion prepared in this invention. After the substitution, the pseudoplasticity of the coating decreased significantly, and the maximum single-coat application film thickness dropped to 80 μm. At the same time, problems such as increased water absorption and decreased drying properties occurred. Furthermore, the monomer composition, functionality, molecular weight, and aqueous dispersion form of the modified amine emulsion can significantly affect the coating's curing activity, rheological properties, mechanical strength, and even chemical resistance. For example, using an appropriate amount of γ-glycidyloxypropyltrimethoxysilane to end-cap the base amine can improve the coating's adhesion to various substrate surfaces, but excessive addition may destabilize the emulsion due to hydrolysis and condensation, reducing the coating's overall performance. For example, in Comparative Example 2, an excess of γ-glycidyloxypropyltrimethoxysilane was used to replace part of butyl glycidyl ether. After the substitution, the overall stability of the amine emulsion decreased, and the adhesion, water resistance, acid and alkali resistance, and salt spray resistance of the coating prepared therefrom also decreased to varying degrees.

[0112] In order to meet the anti-corrosion needs in extreme environments, the present invention selects the anti-rust pigment combination scheme of "aluminum zinc orthophosphate hydrate + inorganic corrosion inhibitor + modified aluminum tripolyphosphate". Through initial corrosion inhibition, long-term foaming inhibition and long-term substrate passivation, a water-based anti-corrosion coating with a salt spray resistance of more than 1200 hours is obtained. In comparison, the traditional monophosphate anti-corrosion strategy (such as Comparative Example 3) is very prone to blistering and rusting of the coating in the early stage of corrosion, and cannot meet the coating service requirements under heavy anti-corrosion conditions. In addition, the present invention also adopts a powder combination scheme of "lightweight filler (hollow glass microspheres) + flaky shielding filler (aluminum powder, sericite) + inert filler (feldspar powder)" to take into account the needs of single-layer thick coating and dielectric shielding. Experiments show that the combination scheme of "10-20μm sericite powder + 15-35μm aluminum powder" has high shielding efficiency and good coating fineness. The appropriate use of lightweight fillers (hollow glass microspheres) can increase the volume solids content of the coating, but excessive addition can impair the coating's cohesive strength and shielding efficiency. Feldspar powder was selected as an inert filler due to its stable chemical properties, low oil absorption, and moderate density. In contrast, if a traditional filler solution were used in place of the filler combination disclosed in this invention (as in Comparative Example 4), the volume solids content, crack resistance during thick coatings, and shielding properties of the coating would be significantly reduced, making it impossible to obtain a heavy-duty corrosion-resistant product suitable for thick-film coatings.

[0113] Furthermore, to achieve the best cross-linking degree and the lowest possible hydrophilic amine residue, the molar ratio of the epoxy groups in component A to the active hydrogens in component B should be strictly controlled within 1: (0.82-0.93). Exceeding this range results in excessive active amine residues (too much component B, as in Comparative Example 5) and reduced cross-linking (too little component B), both of which significantly impact the coating's mechanical properties and protection against corrosive media.

[0114] Finally, the other materials disclosed in this invention were selected after extensive experimentation. Random substitutions can affect the overall performance of the coating. For example, the preferred HEXION HELOXY 505 castor oil polyglycidyl ether, Dispers 757W wetting and dispersing agent, AQUAFLOW XLS-525 thickener, and AQUATIX 8421 wax rheological additive can compromise the coating's sag resistance, drying properties, thick coating crack resistance, and corrosion resistance.

Claims

1. A high build waterborne epoxy heavy duty anti-corrosion coating, characterized in that The coating is composed of component A and component B in a mass ratio of (1-15):1: Component A consists of the following ingredients by mass: Component B consists of the following ingredients by mass: 3-8 parts of anti-flash rust additive 1-3 parts wax rheological additive 90-95 parts of modified amine emulsion.

2. A high build waterborne epoxy heavy duty anti-corrosion coating, characterized in that The coating is composed of component A and component B in a mass ratio of (5-9):1: Component A consists of the following ingredients by mass: Component B consists of the following ingredients by mass: 3-8 parts of anti-flash rust additive 1-3 parts wax rheological additive 90-95 parts of modified amine emulsion.

3. The high build waterborne epoxy heavy duty anti-corrosion coating according to claim 1, characterized in that: The waterborne epoxy resin is one or more of EPIKOTE 7520-WD-52A from Hexion, BECKOPOX EP 384w / 53WAMP from Allnex Chemical, or STW606 from Huayi Fine Chemical; and the castor oil polyglycidyl ether is HEXION HELOXY 505 from Hexion.

4. The high build waterborne epoxy heavy duty anti-corrosion coating according to claim 1, characterized in that The coloring pigment is one or more of rutile titanium dioxide, pigment red 170, pigment red 254, pigment yellow 154, pigment yellow 83, pigment yellow 151, phthalocyanine blue, phthalocyanine green, carbon black and iron oxide red.

5. The high build waterborne epoxy heavy duty anti-corrosion coating according to claim 1, characterized in that The anti-rust pigment is a mixture of HEUCOPHOS ZPA aluminum zinc orthophosphate hydrate, APW-II zinc oxide modified aluminum tripolyphosphate from Xinjing Technology, and JP-B803 inorganic high-efficiency corrosion inhibitor from Junjiang Technology, with the mass ratio of the three being (3-7): (1-4): 0.5-1.

6. The high build waterborne epoxy heavy duty anti-corrosion coating according to claim 1, characterized in that The average particle size of the sericite powder is 10 to 20 μm; the median particle size of the hollow glass microspheres is 20 to 30 μm, preferably: 3M iM16K, S32HS or S28HS hollow glass microspheres; the water-based aluminum-silver paste is a silica-coated passivated aluminum powder paste with an average particle size of 15 to 35 μm, preferably: the water-based aluminum-silver paste is SILBERCOTE AQ ELITE 015LM, SILBERCOTE AQ ULTRA 020LM of Star Platinum, or Hefei Xuyang WHD8008A, Hefei Xuyang WHD8214, Hefei Xuyang WHD8221.

7. The high build waterborne epoxy heavy duty anti-corrosion coating according to claim 1, characterized in that: The wetting and dispersing agent is Digo Dispers 757W; the defoaming agent is Digo Foamex 810; the substrate wetting agent is Digo Wet KL 245; the polyurethane thickener is Ashland AQUAFLOW XLS-525; the anti-flash rust additive is Enze Chemical HY78; The wax rheology additive is BYK AQUATIX 8421.

8. The high build waterborne epoxy heavy duty anti-corrosion coating according to claim 1, characterized in that The modified amine emulsion has a solid content of 45 to 55 wt %, an active hydrogen equivalent of 370 to 500 g / mol, and a molar ratio of epoxy groups in component A to active hydrogen in component B of 1:(0.82 to 0.93). Preferably, the modified amine emulsion is prepared by the following steps: S1: Add toluene, polyethylene glycol monomethyl ether glycidyl ether and 4,4'-diaminodicyclohexylmethane into a reaction kettle, raise the temperature to 80-110°C, and stir to react for 1-2 hours; S2: Add benzyl glycidyl ether and continue the reaction for 0.5 to 1 hour; S3: First add m-xylenediamine, then slowly add a mixed solution of E51 epoxy resin, glycidyl butyl ether, γ-glycidyloxypropyltrimethoxysilane and toluene. After the addition is complete, keep the mixture at 100-120°C for 0.1-1h, and finally add 2,4,6-tris(dimethylaminomethyl)phenol and stir to mix evenly; S4: Remove toluene under reduced pressure and cool to 60-90°C. Slowly add water into the reactor under high-speed stirring. Continue to disperse for 20-40 minutes after addition. Cool and filter to obtain a modified amine emulsion. Preferably, the specific amount of each component in the preparation method of the modified amine emulsion is as follows: Preferably, the polyethylene glycol monomethyl ether glycidyl ether is purchased from Shi Neng, and the model is MPEG-EPO.

9. A method for preparing the high-build waterborne epoxy heavy-duty anti-corrosion coating according to claim 1, characterized in that: The method comprises the following steps: S1: Add water and a wetting and dispersing agent to a paint mixing kettle and stir evenly. Add coloring pigment, anti-rust pigment, fumed silica, and defoamer, and disperse at high speed until there are no lumps or agglomerates. Transfer the slurry to a sand mill and grind to a fineness of less than 40 μm. Add water-based epoxy resin, castor oil polyglycidyl ether, dipropylene glycol butyl ether, ethanol, a substrate wetting agent, feldspar powder, sericite powder, hollow glass microspheres, a water-based aluminum-silver paste, and an isothiazolinone fungicide to the ground slurry in sequence, stirring and dispersing until the material fineness is less than 80 μm. Add a polyurethane thickener and adjust the system viscosity to 80-120 KU (Stormer viscometer). Filter to obtain component A. S2: Add the modified amine emulsion to a paint mixing kettle, add an anti-flash rust agent and a wax rheology additive, and stir evenly. Filter to obtain component B. S3: Mix component A and component B evenly, and add water to dilute them to obtain a thick paste type water-based epoxy heavy anti-corrosion coating.

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