Anticorrosive paint as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coatings, and relates to an anticorrosive coating as well as a preparation method and application thereof. The invention provides a preparation method of an anti-corrosion coating, which comprises the following steps: stirring and mixing epoxy resin, an auxiliary agent, an anti-corrosion filler, a filler, a modified pigment and a first solvent, grinding and filtering to obtain the anti-corrosion coating, the preparation method comprises the following steps: carrying out surface modification on wet-process mica powder by adopting 1-ethyl-(3-dimethylaminopropyl) carbodiimide to obtain modified wet-process mica powder, and connecting an organic pigment to the surface of the modified wet-process mica powder by adopting a silane coupling agent in a second solvent to obtain the modified pigment. The invention solves the technical problem of poor stability when the organic pigment is used for the anticorrosive paint.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings and relates to an anti-corrosion coating and a preparation method and application thereof. Background Art

[0002] Metal corrosion is a common phenomenon in production and life, involving all walks of life, and its harm is increasing day by day, causing huge losses to economic and social development. Anti-corrosion coatings are often used in the protection of metal equipment due to their wide selectivity, wide range of applications, convenient application and construction, and energy saving. The main functions of anti-corrosion coatings in the protection of metal equipment include shielding effect, corrosion inhibition effect and cathodic protection. Anti-corrosion coatings are divided into epoxy resin anti-corrosion coatings, polyurethane coatings, vinyl resin coatings, rubber coatings, fluorocarbon coatings and silicone coatings according to the main film-forming substances. Among them, polyurethane coatings are limited by high costs and complex construction processes; vinyl resin coatings have low solid content and poor coating adhesion; rubber coatings have poor resistance to chemical reagents and solvents; fluorocarbon coatings have high brittleness and high cost; silicone coatings have poor adhesion and high cost. Compared with the above coatings, epoxy resin anti-corrosion coatings are lower in cost and have excellent corrosion resistance and strong adhesion. They are one of the most widely used anti-corrosion coatings for metal equipment.

[0003] As a high molecular weight polymer, the molecular formula of epoxy resin is as follows:

[0004] Its anti-corrosion performance is mainly achieved through the barrier effect of corrosive ions, water and oxygen. Epoxy resin forms a dense three-dimensional cross-linked network inside through the ring-opening reaction with amines and other compounds or monomers, realizing the film hardening of the coating. Based on the dense cross-linked network and electrical insulation of epoxy resin after curing, as well as the sacrificial anode effect of metal powder filler, epoxy resin anti-corrosion coatings show good anti-corrosion performance. CN115975481A discloses an epoxy resin anticorrosive coating and a preparation method thereof, belonging to the technical field of anticorrosive coatings. The epoxy resin anticorrosive coating comprises component A and component B, wherein the mass ratio of component A to component B is (5-8):1, component A comprises the following components in parts by weight: 20-35 parts of epoxy resin, 15-25 parts of zinc powder, 0.2-2.5 parts of silicon dioxide, 12-30 parts of filler, 3-6 parts of silane coupling agent and 20-40 parts of organic solvent, and component B comprises the following components in parts by weight: 40-60 parts of polyamide curing agent, 1-3 parts of foamed graphene powder and 1-2 parts of silane coupling agent; the anticorrosive coating can effectively solve the problem of poor anticorrosive performance of existing anticorrosive coatings. CN116478599A discloses a self-repairing epoxy resin anticorrosive coating and a preparation method thereof; the self-repairing epoxy resin anticorrosive coating comprises a flexible molecular chain, modified graphene oxide, epoxy resin and a curing agent. The preparation method comprises the following steps: step 1, adding a flexible molecular chain to an epoxy resin, stirring evenly, and obtaining a mixed dispersion A; step 2, ultrasonically dispersing modified graphene oxide in N,N-dimethylformamide, and obtaining a mixed dispersion B; step 3, pouring the mixed dispersion B into the mixed dispersion A and stirring and mixing evenly, and obtaining a mixed dispersion C; step 4, adding a curing agent to the mixed dispersion C, stirring evenly, and vacuum degassing, and after the vacuum degassing is completed, a self-repairing epoxy resin anti-corrosion coating is obtained. The present invention can solve the problem that the existing intrinsic self-repairing anti-corrosion coating requires a large amount of energy for self-healing and the mechanical properties of the repaired coating are affected. Although epoxy resin anti-corrosion coatings present multiple advantages in anti-corrosion applications, there are still many problems. On the one hand, the coating is brittle and easy to crack after film formation, resulting in a decrease in corrosion resistance. This is because the epoxy resin is rich in epoxy groups, and the cross-linked network formed after reacting with the curing agent is mostly covalently bonded, which makes it difficult to achieve effective stress dissipation, resulting in the formed coating being rigid and insufficiently tough, and easy to crack brittlely. The cracked coating is difficult to resist the intrusion of water and corrosive media, which reduces the corrosion resistance of the coating. On the other hand, the pigments used in anti-corrosion coatings are mainly inorganic pigments, and organic pigments cannot be used. The color of inorganic pigments is relatively stable and is not easily affected by climate and sunlight, so they are suitable for outdoor use or places exposed to sunlight for a long time. Organic pigments can produce pigments of various colors with bright colors and a complete color spectrum. Since organic pigments are easily affected by environmental factors, they are more likely to change color or fade when exposed to sunlight for a long time or affected by factors such as oxidation. Summary of the invention

[0005] The purpose of the present invention is to obtain an anti-corrosion coating containing organic pigments, and in particular to solve the technical problem that when organic pigments are used in anti-corrosion coatings, they are more likely to change color or fade when exposed to sunlight for a long time or affected by factors such as oxidation. In this regard, the present invention provides a moisturizing and anti-oxidation essence and a preparation method thereof to solve this need in the art.

[0006] It should be understood that the expression "at least one of" includes individually each of the items recited after the expression and various different combinations of two or more of the recited items, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited items should be understood to have the same meaning, unless otherwise understood from the context.

[0007] The use of the terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, for example not excluding other unrecited elements or steps, unless otherwise specifically stated or otherwise understood from the context.

[0008] It should be understood that the order of steps or the order in which certain actions are performed is not important as long as the present invention remains operable. In addition, two or more steps or actions may be performed simultaneously.

[0009] The use of any and all examples or exemplary language, such as "for example" or "including", herein is intended only to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating that any non-claimed element is essential to the practice of the invention.

[0010] In addition, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, quantities, values ​​and percentages used in this disclosure are modified by "about". Here, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0011] On the one hand, the present invention relates to a method for preparing an anticorrosive coating, which comprises: mixing epoxy resin, an additive, an anticorrosive filler, a filler, a modified pigment and a first solvent, grinding and filtering to obtain the anticorrosive coating;

[0012] The wet-process mica powder is surface-modified by using 1-ethyl-(3-dimethylaminopropyl)carbodiimide to obtain a modified wet-process mica powder, and an organic pigment is connected to the surface of the modified wet-process mica powder by using a silane coupling agent in a second solvent to obtain the modified pigment.

[0013] Furthermore, in the method for preparing the anti-corrosion coating provided by the present invention, the epoxy resin is selected from one of bisphenol A epoxy resin, phenolic epoxy resin or silicone epoxy resin.

[0014] Furthermore, in the method for preparing the anti-corrosion coating provided by the present invention, the auxiliary agent consists of a dispersant and a defoaming agent.

[0015] Furthermore, in the method for preparing the anti-corrosion coating provided by the present invention, the defoaming agent is tributyl phosphate or dimethyl silicone oil.

[0016] Furthermore, in the preparation method of the anti-corrosion coating provided by the present invention, the dispersant is selected from one of polyethylene wax, polyvinyl pyrrolidone, sodium carboxymethyl cellulose, and polyethylene glycol.

[0017] Furthermore, in the method for preparing the anticorrosive coating provided by the present invention, the filler is selected from one of talc, barium sulfate and calcium carbonate;

[0018] The anti-corrosion filler is at least one of red iron oxide, aluminum tripolyphosphate, and boron nitride;

[0019] The silane coupling agent is KH-560 silane coupling agent.

[0020] Furthermore, in the preparation method of the anti-corrosion coating provided by the present invention, there is no particular limitation on the selection of the silane coupling agent. Those skilled in the art can reasonably select from the existing silane coupling agents used for epoxy resin anti-corrosion coatings. The silane coupling agent includes at least one of isobutyltriethoxysilane coupling agent, isobutyltrimethoxysilane coupling agent, methyltrimethoxysilane coupling agent, methyltriethoxysilane coupling agent, methyldimethoxysilane coupling agent and methyldiethoxysilane coupling agent.

[0021] Furthermore, in the preparation method of the anti-corrosion coating provided by the present invention, there is no particular limitation on the selection of the first solvent. Those skilled in the art can reasonably select from the existing solvents used for epoxy resin anti-corrosion coatings, such as toluene, xylene, ketones and other solvents, and those skilled in the art can also reasonably adjust the amount of solvent added. The amount of solvent added is related to the viscosity requirement of the coating to be prepared, and can be reasonably adjusted according to the specific use environment and performance requirements of the coating.

[0022] Furthermore, in the preparation method of the anti-corrosion coating provided by the present invention, the second solvent is a mixture of cyclohexanone and butyl acetate, and the mass ratio of cyclohexanone to butyl acetate is 1-3:4-7.

[0023] Furthermore, in the preparation method of the anticorrosive coating provided by the present invention, the raw materials for preparing the anticorrosive coating are composed of the following components in parts by mass: 30 to 50 parts of epoxy resin, 3 to 10 parts of auxiliary agent, 10 to 20 parts of anticorrosive filler, 15 to 30 parts of filler, 10 to 15 parts of modified pigment, and 10 to 30 parts of first solvent;

[0024] When the modified pigment is prepared, the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to wet-process mica powder is 1-3:1, and the mass ratio of the modified wet-process mica powder, the second solvent, the silane coupling agent and the organic pigment is 3-5:20-30:0.3-0.5:10.

[0025] On the other hand, the present invention relates to an anti-corrosion coating, which is prepared by any of the methods for preparing the anti-corrosion coating described above.

[0026] Preferably, one or more cosolvents selected from the group consisting of aliphatic alcohols, ketones, esters, glycols, glycol ethers, glycol esters, and mixtures thereof are added, and preferably one or more additives selected from the group consisting of defoamers, leveling agents, coalescing agents, flow modifiers, bactericides, pigments, and rheological additives are added.

[0027] If a colored coating composition is prepared, a wetting agent and an anti-settling agent may also be added. Representative alcohols include ethanol, n-propanol, isopropanol, n-butanol, and isobutanol; representative ketones include acetone, 2-butanone, cyclohexanone, methyl aryl ketone, ethyl aryl ketone, and methyl isoamyl ketone; representative esters include ethyl acetate and butyl acetate; representative glycols include ethylene glycol and propylene glycol; representative glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, and methoxypropanol; representative glycol esters include butylene glycol acetate and methoxypropyl acetate.

[0028] Preferably, one or more crosslinking catalysts are added to the coating composition, selected from salts, chelate compounds and organometallic compounds of elements of groups 4, 7, 8, 9, 12, 13, 14 and 15 and periods 4, 5 and 6 of the Periodic Table of the Elements according to the new IUPAC nomenclature system, and strong amines.

[0029] Preferred are compounds that are readily soluble in water, such as salts of these elements that dissociate into ions in an aqueous system, and chelates of these elements, wherein the chelate former may be an organic hydroxy acid, such as lactic acid, 2,2-dimethylolpropionic acid, an amino acid such as N,N,N',N'-ethylenediaminetetraacetic acid, nitrilotriacetic acid, β-alanine, or a polyfunctional amine or hydroxylamine. Other compounds that can be used are organometallic compounds, such as alkoxymetal oxides, and metal salts of organic acids or hydroxy acids. Particularly preferred are methanesulfonates, lactates and dimethylolpropionic acid salts of bismuth, tin, lead and titanium.

[0030] The strong amine is more preferably a tertiary amine and most preferably a (poly)cyclic tertiary amine such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO).

[0031] The coating composition may comprise one or more organic and inorganic pigments and optionally one or more fillers.

[0032] Examples of inorganic pigments are iron oxide pigments, titanium oxide pigments, zinc oxide pigments, chromium oxide pigments coprecipitated with nickel and nickel titanate, yellow pigments from lead sulfochromate or lead bismuth vanadate, orange pigments from lead sulfochromate molybdate, and carbon black.

[0033] Examples of suitable organic pigments are azo pigments, metal complex pigments, anthraquinone pigments, phthalocyanine pigments, polycyclic pigments, especially those of the thioindigo, quinacridone, dioxazine, pyrrolo, naphthalenetetracarboxylic acid, perylene, isoamidinoline (one), flavonanthrone, pyrone or isoviolanthrone series.

[0034] Examples of fillers which can be used are kaolin, talc, silicates, quartz, cristobalite, wollastonite, perlite, diatomaceous earth, fibrous fillers, aluminum hydroxide, barium sulfate or calcium carbonate.

[0035] On the other hand, the present invention relates to the application of the anti-corrosion coating in the anti-corrosion of metal surfaces.

[0036] The coating composition of the present invention is preferably applied to a metal substrate, more preferably to a corrosion resistant pretreated metal substrate, even more preferably to an iron phosphate or zinc phosphate sheathed steel plate or to a pretreated steel plate comprising a zirconium-based, vanadium-based, titanium-based or silane-based conversion coating.

[0037] The coating composition may be applied to the substrate using any suitable procedure known in the art, and is preferably applied by spraying or dipping.

[0038] The water and optional co-solvent are then flashed off at a temperature of at least 20°C for at least 1 minute, preferably at a temperature of at least 20°C for at least 5 minutes, followed by baking in a ventilated convection oven at a temperature of at least 140°C, preferably 140-230°C, more preferably 150-220°C, even more preferably 160-210°C, most preferably 170-200°C for at least 20 seconds, preferably 1-25 minutes, more preferably 2-20 minutes, even more preferably 4-18 minutes, still even more preferably 6-15 minutes, most preferably 8-12 minutes.

[0039] Alternatively, the coating may be cured by infrared radiation (e.g., near infrared, short infrared, or mid infrared) or by induction or by a combination thereof. In embodiments using infrared or induction systems, the baking cycle is in the range of 2-160 seconds, depending on the heating system or combination of heating systems.

[0040] Furthermore, the coating composition generally comprises a curing agent. In the coating composition provided by the present invention, there is no particular limitation on the selection and amount of the curing agent.

[0041] Generally, those skilled in the art can reasonably choose from the existing curing agents for epoxy resin anti-corrosion coatings, for example, amine curing agents include aliphatic amines, aromatic amines, alicyclic amines, polyamides, imidazoles, etc.; acid anhydride curing agents include maleic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc.; phenolic curing agents include phenolic resins, phenolic modified resins, new phenolic resins, etc.; isocyanate curing agents include methanol isocyanate, polyisocyanates, polyether polyols, etc.

[0042] Preferably, the curing agent in the coating composition is polyamide, and the usage ratio of polyamide to other non-curing agent components is 1:5-10 by mass ratio.

[0043] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0044] The present invention provides a method for preparing an anticorrosive coating, wherein epoxy resin, an additive, an anticorrosive filler, a filler, a specially modified pigment and a first solvent are stirred and mixed, and then ground and filtered to obtain the anticorrosive coating. The modified pigment is obtained by surface-modifying wet-process mica powder with 1-ethyl-(3-dimethylaminopropyl)carbodiimide to obtain modified wet-process mica powder, and then connecting an organic pigment to the surface of the modified wet-process mica powder with a silane coupling agent in a second solvent. This special method for preparing modified pigments effectively solves the technical problem of poor stability of organic pigments when used in anticorrosive coatings, so that the prepared anticorrosive coating is not easy to change color or fade when exposed to sunlight for a long time or affected by factors such as oxidation.

[0045] In addition, the present invention also optimizes the selection of raw materials, such as the epoxy resin is selected from one of bisphenol A epoxy resin, phenolic epoxy resin or silicone epoxy resin, the auxiliary agent is composed of a dispersant and a defoamer, and the anticorrosive filler is at least one of red iron oxide, aluminum tripolyphosphate, and boron nitride, etc. These selections are all helpful to improve the anticorrosive performance and stability of the coating. At the same time, the present invention also reasonably allocates the selection and ratio of the solvent, such as the second solvent is a mixture of cyclohexanone and butyl acetate, and the mass ratio is within a certain range, which helps to further improve the performance of the coating.

[0046] In terms of coating application, the anticorrosive coating provided by the present invention can be applied to various metal substrates, and is particularly suitable for corrosion-resistant pretreated metal substrates, such as iron phosphate or zinc phosphate sheathed steel plates or pretreated steel plates containing zirconium-based, vanadium-based, titanium-based or silane-based conversion coatings. The coating composition generally also includes a curing agent, and the type and amount of the curing agent can be selected as required. The coating method can be any suitable process known in the art such as spraying or dipping.

[0047] Compared with the prior art, the anticorrosive coating of the present invention has significantly improved stability and anticorrosion performance, and the preparation method is simple and feasible, the raw material source is wide, and it has high industrial application value. At the same time, the coating composition of the present invention also has good adhesion and corrosion resistance, which can meet the anticorrosion requirements of different metal equipment and provide a strong guarantee for the long-term stable operation of metal equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 The results of sample stability test. DETAILED DESCRIPTION

[0050] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials described are available on the market unless otherwise specified. The % in the following embodiments are all mass percentages unless otherwise specified. The ratios in the following embodiments are all mass ratios unless otherwise specified.

[0051] Example 1

[0052] This embodiment provides a process for preparing an anti-corrosion coating and a process for applying the coating composition.

[0053] (1) Preparation of modified pigments:

[0054] 1-Ethyl-(3-dimethylaminopropyl)carbodiimide and wet-process mica powder were mixed in a mass ratio of 1:1, and the liquid was filtered after being placed in a water bath at 35°C for 1 hour to obtain modified wet-process mica powder. A mixture of cyclohexanone and butyl acetate was prepared with a mass ratio of cyclohexanone to butyl acetate of 1:7 as the second solvent. The modified wet-process mica powder, the second solvent, KH-560 silane coupling agent and phthalocyanine blue B were mixed in a mass ratio of 3:20:0.3:10, and then stirred at a speed of 800r / min for 60min in a water bath at 35°C, the excess solvent was removed by centrifugation, and then vacuum dried to obtain the modified pigment.

[0055] (2) Preparation of anti-corrosion coating:

[0056] The following raw materials are taken by weight: 30 parts of bisphenol A epoxy resin, 2.5 parts of polyethylene wax, 0.5 parts of tributyl phosphate, 10 parts of aluminum tripolyphosphate, 15 parts of talc, 10 parts of modified pigment, and 10 parts of the first solvent. The first solvent is the same as the second solvent.

[0057] Add 10 parts of bisphenol A epoxy resin, 0.5 parts of tributyl phosphate and 10 parts of modified pigment to 8 parts of the first solvent, stir at 500 r / min for 60 minutes, add the remaining raw materials, vacuum dry and grind, stir at 1500 r / min for 120 minutes, filter to a fineness of less than 80 μm, and package the material to obtain an anti-corrosion coating.

[0058] (3) Coating composition

[0059] The polyamide and the anti-corrosion coating are uniformly mixed in a mass ratio of 1:5 to obtain a coating composition, which is applied to a substrate.

[0060] Example 2

[0061] This embodiment provides a process for preparing an anti-corrosion coating and a process for applying the coating composition.

[0062] (1) Preparation of modified pigments:

[0063] 1-Ethyl-(3-dimethylaminopropyl)carbodiimide and wet-process mica powder were mixed in a mass ratio of 2:1, and the liquid was filtered after being placed in a water bath at 35°C for 1 hour to obtain modified wet-process mica powder. A mixture of cyclohexanone and butyl acetate was prepared with a mass ratio of cyclohexanone to butyl acetate of 2:5 as the second solvent. The modified wet-process mica powder, the second solvent, KH-560 silane coupling agent and BASF K3911 Pigment Red 178 were mixed in a mass ratio of 4:22:0.4:10, and then stirred at a speed of 800r / min for 60min in a water bath at 35°C, the excess solvent was removed by centrifugation, and then vacuum dried to obtain the modified pigment.

[0064] (2) Preparation of anti-corrosion coating:

[0065] The following raw materials are taken by mass: 40 parts of phenolic epoxy resin, 3 parts of sodium carboxymethyl cellulose, 2 parts of dimethyl silicone oil, 12 parts of red iron oxide, 18 parts of barium sulfate, 12 parts of modified pigment, and 12 parts of the first solvent. The first solvent is the same as the second solvent.

[0066] Add 12 parts of phenolic epoxy resin, 0.5 parts of dimethyl silicone oil and 10 parts of modified pigment to 10 parts of the first solvent, stir at 500 r / min for 60 minutes, add the remaining raw materials, vacuum dry and grind, stir at 1500 r / min for 120 minutes, filter to a fineness of less than 80 μm, and package the material to obtain an anti-corrosion coating.

[0067] (3) Coating composition

[0068] The polyamide and the anti-corrosion coating are uniformly mixed in a mass ratio of 1:6 to obtain a coating composition, which is applied to a substrate.

[0069] Example 3

[0070] This embodiment provides a process for preparing an anti-corrosion coating and a process for applying the coating composition.

[0071] (1) Preparation of modified pigments:

[0072] 1-Ethyl-(3-dimethylaminopropyl)carbodiimide and wet-process mica powder were mixed in a mass ratio of 2:1, and the liquid was filtered after being placed in a water bath at 35°C for 1 hour to obtain modified wet-process mica powder. A mixture of cyclohexanone and butyl acetate was prepared with a mass ratio of cyclohexanone to butyl acetate of 2:5 as the second solvent. The modified wet-process mica powder, the second solvent, KH-560 silane coupling agent and BASF K3911 Pigment Red 178 were mixed in a mass ratio of 4:25:0.4:10, and then stirred at a speed of 800r / min for 60min in a water bath at 35°C, the excess solvent was removed by centrifugation, and then vacuum dried to obtain the modified pigment.

[0073] (2) Preparation of anti-corrosion coating:

[0074] The following raw materials are taken by weight: 40 parts of phenolic epoxy resin, 4 parts of sodium carboxymethyl cellulose, 3 parts of dimethyl silicone oil, 15 parts of red iron oxide, 18 parts of barium sulfate, 12 parts of modified pigment, and 20 parts of the first solvent. The first solvent is the same as the second solvent.

[0075] Add 12 parts of phenolic epoxy resin, 2 parts of dimethyl silicone oil and 10 parts of modified pigment to 15 parts of the first solvent, stir at 500 r / min for 60 minutes, add the remaining raw materials, vacuum dry and grind, stir at 1500 r / min for 120 minutes, filter to a fineness of less than 80 μm, and package the material to obtain an anti-corrosion coating.

[0076] (3) Coating composition

[0077] The polyamide and the anti-corrosion coating are uniformly mixed in a mass ratio of 1:8 to obtain a coating composition, which is applied to a substrate.

[0078] Example 4

[0079] This embodiment provides a process for preparing an anti-corrosion coating and a process for applying the coating composition.

[0080] (1) Preparation of modified pigments:

[0081] 1-Ethyl-(3-dimethylaminopropyl)carbodiimide and wet-process mica powder were mixed in a mass ratio of 3:1, and the liquid was filtered after being placed in a water bath at 35°C for 1 hour to obtain modified wet-process mica powder. A mixture of cyclohexanone and butyl acetate was prepared in a mass ratio of 3:4 as the second solvent. The modified wet-process mica powder, the second solvent, KH-560 silane coupling agent and BASF K3911 Pigment Red 178 were mixed in a mass ratio of 4:25:0.4:10, and then stirred at a speed of 800r / min for 60min in a water bath at 35°C, the excess solvent was removed by centrifugation, and then vacuum dried to obtain the modified pigment.

[0082] (2) Preparation of anti-corrosion coating:

[0083] The following raw materials are taken by weight: 50 parts of silicone epoxy resin, 8 parts of sodium carboxymethyl cellulose, 2 parts of dimethyl silicone oil, 20 parts of red iron oxide, 30 parts of barium sulfate, 15 parts of modified pigment, and 30 parts of the first solvent. The first solvent is the same as the second solvent.

[0084] Add 30 parts of phenolic epoxy resin, 2 parts of dimethyl silicone oil and 15 parts of modified pigment to 20 parts of the first solvent, stir at a speed of 500 r / min for 60 minutes, add the remaining raw materials, grind after vacuum drying, stir at a speed of 1500 r / min for 120 minutes, filter to a fineness of less than 80 μm, and package the material to obtain an anti-corrosion coating.

[0085] (3) Coating composition

[0086] The polyamide and the anti-corrosion coating are uniformly mixed in a mass ratio of 1:10 to obtain a coating composition, which is applied to a substrate.

[0087] Comparative Example 1

[0088] This comparative example provides a preparation process of an anti-corrosion coating and an application process of a coating composition, and is intended to illustrate the effect of wet-process mica powder on the performance of the anti-corrosion coating.

[0089] This comparative example is the same as Example 4, except that the wet-process mica powder is replaced by dry-process mica powder.

[0090] Comparative Example 2

[0091] This comparative example provides a preparation process of an anti-corrosion coating and an application process of the coating composition. This comparative example is intended to illustrate the effect of surface modification of wet-process mica powder by 1-ethyl-(3-dimethylaminopropyl)carbodiimide on the performance of the anti-corrosion coating.

[0092] This comparative example is the same as Example 4, except that the wet-process mica powder is not modified by 1-ethyl-(3-dimethylaminopropyl)carbodiimide.

[0093] Comparative Example 3

[0094] This comparative example provides a preparation process of an anti-corrosion coating and an application process of a coating composition, and this comparative example intends to distinguish between wet-process mica powder as an organic pigment carrier and wet-process mica powder as an anti-corrosion filler.

[0095] This comparative example is the same as Example 4, except that the wet-process mica powder does not undergo the "preparation of modified pigment" process, but all raw materials are used for the preparation of anti-corrosion coatings.

[0096] Test Example 1

[0097] This test example is used to test the stability of the above anti-corrosion coatings and coating compositions.

[0098] According to the test method of GB / T 1735-2009, the test block was placed at 230℃ and 20% humidity for 7 days for stability test, and the CIE-L * a * b* Value (International universal color representation standard, L * : brightness, a * : Red and green color balance, b * : Yellow-blue color balance), get the ΔE value (the smaller the ΔE value, the smaller the color difference before and after the pigment test), the test results are as follows Figure 1 shown.

[0099] Depend on Figure 1 It can be seen that after the anticorrosive coatings prepared in Example 1, Example 2, Example 3 and Example 4 are applied to the substrate, their ΔE values ​​are 1.28, 1.89, 2.2 and 1.68 respectively, indicating that the coating composition obtained has better pigment stability under harsh external environment, avoiding the degradation problem of organic pigments when used in anticorrosive coatings. From Comparative Example 1, it can be seen that after the dry mica powder replaces the wet mica powder, it does not have the effect of improving the stability of organic pigments. This may be because the dry mica powder has a low diameter-to-thickness ratio, and the mica crystal and flaky structure are easily destroyed, and the organic pigment cannot be well loaded; the wet mica powder has a large diameter-to-thickness ratio, retains the flaky structure of mica, has a smooth surface, high gloss, better cementation, dispersibility and adhesion, and can load organic pigments well. It can be seen from Comparative Examples 2 and 3 that the stability of organic pigments is also poor, which shows that surface modification of wet-process mica powder with 1-ethyl-(3-dimethylaminopropyl)carbodiimide can improve the loading and connecting effect of wet-process mica powder on organic pigments. If the loading and connecting process is not carried out, the stability of the organic pigments will also be affected.

[0100] Test Example 2

[0101] This test example is used to test the anti-corrosion performance of the above anti-corrosion coatings and coating compositions.

[0102] The test items and methods are shown in Table 1.

[0103] Table 1, Anticorrosion Performance Test

[0104]

[0105]

[0106] It can be seen from Table 1 that the anti-corrosion coating and coating composition provided by the present invention have better adhesion than Comparative Example 1, and have better anti-corrosion performance than Comparative Examples 2 and 3.

[0107] As described above, the basic principle, main features and advantages of the present invention are well described. The above embodiments and descriptions are only descriptions of the preferred implementation modes of the present invention, and the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the protection scope determined by the present invention.

Claims

1. A method for preparing an anticorrosive coating, characterized in that: include: The epoxy resin, the additive, the anticorrosive filler, the filler, the modified pigment and the first solvent are stirred and mixed, and then ground and filtered to obtain the anticorrosive coating; The wet-process mica powder is surface-modified by using 1-ethyl-(3-dimethylaminopropyl)carbodiimide to obtain a modified wet-process mica powder, and an organic pigment is connected to the surface of the modified wet-process mica powder by using a silane coupling agent in a second solvent to obtain the modified pigment.

2. The method for preparing the anticorrosive coating according to claim 1, characterized in that: The epoxy resin is selected from bisphenol A epoxy resin, novolac epoxy resin or silicone epoxy resin.

3. The method for preparing the anticorrosive coating according to claim 1, characterized in that: The auxiliary agent consists of a dispersant and a defoamer.

4. The method for preparing the anticorrosive coating according to claim 3, characterized in that: The defoaming agent is tributyl phosphate or dimethyl silicone oil.

5. The method for preparing the anticorrosive coating according to claim 3, characterized in that: The dispersant is selected from one of polyethylene wax, polyvinyl pyrrolidone, sodium carboxymethyl cellulose and polyethylene glycol.

6. The method for preparing the anticorrosive coating according to claim 1, characterized in that: The filler is selected from one of talc, barium sulfate and calcium carbonate; The anti-corrosion filler is at least one of red iron oxide, aluminum tripolyphosphate, and boron nitride; The silane coupling agent is KH-560 silane coupling agent.

7. The method for preparing the anticorrosive coating according to claim 1, characterized in that: The second solvent is a mixture of cyclohexanone and butyl acetate, and the mass ratio of cyclohexanone to butyl acetate is 1-3:4-7.

8. The method for preparing the anticorrosive coating according to claim 1, characterized in that: The raw materials for preparing the anticorrosive coating are composed of the following components by mass: 30-50 parts of epoxy resin, 3-10 parts of auxiliary agent, 10-20 parts of anticorrosive filler, 15-30 parts of filler, 10-15 parts of modified pigment, and 10-30 parts of first solvent; When the modified pigment is prepared, the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to wet-process mica powder is 1-3:1, and the mass ratio of the modified wet-process mica powder, the second solvent, the silane coupling agent and the organic pigment is 3-5:20-30:0.3-0.5:

10.

9. An anticorrosive coating, characterized in that: The anti-corrosion coating is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the anticorrosive coating according to claim 9 in anticorrosion of metal surfaces.

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