An aqueous epoxy anti-corrosion primer and its preparation method

Abstract

The present invention discloses an aqueous epoxy anti-corrosion primer and a preparation method thereof. In this aqueous epoxy anti-corrosion primer, component A is composed of the following raw materials: deionized water I, anti-settling agent, water glass, dispersant, defoamer I, pigment, anti-rust pigment, mica powder, precipitated barium sulfate, talc powder, aqueous epoxy emulsion, defoamer II, wetting agent, polyurethane thickener, film-forming aid, alkali-swellable thickener. The present invention uses water glass as an alkaline compound for adjusting pH in the aqueous epoxy system, which can enable the alkali-swellable thickener to play a role, improve the low-shear viscosity of the system, and obtain a sag-resistant aqueous epoxy anti-corrosion primer with a high film thickness; meanwhile, it can undergo a self-crosslinking reaction during the film-forming process, condense to form an inorganic polymer compound, and thereby improve water resistance. In addition, this pH regulator is different from traditional organic amine compounds and will not react with the epoxy groups in the epoxy emulsion, which is beneficial to the long-term storage stability of the aqueous epoxy primer.

Description

Technical Field

[0001] The present invention relates to the field of industrial anti-corrosion coatings, and particularly to a waterborne epoxy anti-corrosion primer and a preparation method thereof. Background Art

[0002] Waterborne coatings have the advantages of environmental friendliness, low VOCs, non-flammability and non-explosiveness, and have become one of the fastest-growing varieties of environmentally friendly coatings. Among them, waterborne epoxy primers are commonly used for direct coating on the surface of metal substrates to play an anti-corrosion role. With the increasingly widespread use of high-pressure airless spraying technology, different from traditional air spray gun spraying, the dry film thickness of a single spray is as high as 50-100 microns, much higher than the single film thickness of 30-50 microns of traditional air spray gun spraying. Therefore, it is easy to cause sagging of the paint film. The common practice is to increase the low-shear viscosity of the coating, that is, to increase the thixotropic index Ti value of the system.

[0003] In conventional waterborne coatings, increasing the low-shear viscosity usually uses hydroxyethyl cellulose, organically modified bentonite, alkali-swellable thickeners, polyurethane thickeners, etc. Among them, using alkali-swellable thickening is the most economical and effective method and is widely used in waterborne interior and exterior wall coatings. This method requires adjusting the pH value of the coating to an alkaline condition of 8-9, so that the carboxyl groups of the intertwined alkali-swellable thickeners undergo acid-base neutralization reactions and the resin is dissolved, thereby thickening the system. Commonly used pH regulators include inorganic small molecules such as NaOH, KOH, ammonia water, etc., and some organic amine compounds such as AMP-95, dimethylethanolamine DMEA, triethylamine, etc. However, these small-molecule inorganic basic compounds with strong ionic properties and unable to volatilize during the film-forming process seriously affect the water resistance and anti-corrosion performance of the metal substrate. And the amine-containing organic compounds that are easy to volatilize during the film-forming process do not affect the water resistance, but are prone to react with the epoxy groups in the waterborne epoxy primer during the storage of the coating, resulting in a decrease in pH value and affecting the system stability (this is also the main film-forming curing mechanism of epoxy paint - using the active hydrogen atoms on the organic amine to undergo ring-opening reactions with the epoxy groups. Although tertiary amines do not contain active hydrogen atoms, they can catalyze the self-polymerization reaction of epoxy groups, making the system unstable).

[0004] The above reasons limit the application of alkali-swellable thickeners in waterborne epoxy systems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, and propose a waterborne epoxy anti-corrosion primer and a preparation method thereof, so as to solve the technical problems that the waterborne epoxy coating system using alkali-swellable thickeners to increase the low-shear viscosity of the system often leads to poor water resistance or unstable system in the prior art.

[0006] In a first aspect, the present invention provides an aqueous epoxy anti-corrosion primer, comprising Component A and Component B; wherein, by weight percentage, Component A is composed of the following raw materials: deionized water I 10 - 30%, anti-settling agent 0.1 - 1%, water glass 0.1 - 1%, dispersant 0.5 - 2%, defoaming agent I 0.1 - 1%, pigment 5 - 20%, anti-rust pigment 1 - 15%, mica powder 1 - 10%, precipitated barium sulfate 5 - 30%, talc powder 1 - 15%, aqueous epoxy emulsion 25 - 45%, defoaming agent II 0.1 - 1%, wetting agent 0.1 - 1%, polyurethane thickener 0 - 2%, film-forming aid 1 - 5%, alkali-swellable thickener 0.1 - 1%; Component B is composed of the following raw materials: aqueous epoxy curing agent 30 - 65%, deionized water II 25 - 45%, co-solvent 5 - 20%, anti-corrosion agent 1 - 10%.

[0007] In a second aspect, the present invention provides a preparation method of an aqueous epoxy anti-corrosion primer, comprising the following steps:

[0008] Mix part of deionized water I and the anti-settling agent, and mix evenly under medium-speed dispersion. Subsequently, sequentially add water glass, dispersant, and defoaming agent I, and sequentially add pigment, anti-rust pigment, mica powder, precipitated barium sulfate, and talc powder under high-speed dispersion, continue to disperse until uniform without particles, grind the mixture to a fineness of less than 40 microns, then mix with the aqueous epoxy emulsion, and sequentially add defoaming agent II and wetting agent under medium-speed dispersion and mix evenly. Then add the premixed mixture of polyurethane thickener and film-forming aid, continue to disperse evenly, and then add the premixed mixture of alkali-swellable thickener and the remaining deionized water I, and mix evenly under high-speed dispersion to obtain Component A.

[0009] Mix the aqueous epoxy curing agent and deionized water II, and then sequentially add the co-solvent and anti-corrosion agent under medium-speed dispersion, and continue to disperse evenly to obtain Component B.

[0010] Mix Component A and Component B evenly to obtain the aqueous epoxy anti-corrosion primer.

[0011] Compared with the prior art, the beneficial effects of the present invention include:

[0012] The present invention uses water glass as the alkaline compound for adjusting the pH in the aqueous epoxy system, which can adjust the pH value of the system to be alkaline, enabling the alkali-swellable thickener to play a role and improving the low-shear viscosity of the system, thereby facilitating the improvement of the one-time film-forming thickness and obtaining an anti-sagging aqueous epoxy anti-corrosion primer with a high film thickness; at the same time, due to the silicic acid structure of water glass, it can undergo a self-crosslinking reaction during the film-forming process, condense to form an inorganic polymer compound, and further improve the water resistance. In addition, this pH regulator is different from traditional organic amine compounds, does not contain organic amines, and will not react with the epoxy groups in the epoxy emulsion, which is beneficial to the long-term storage stability of the aqueous epoxy primer. Detailed implementation mode

[0013] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0014] Existing waterborne epoxy primers are made from E20 solid epoxy resin emulsions. To increase the film thickness in a single application, it is necessary to increase the low-shear viscosity of the coating, that is, to increase the thixotropy index Ti value of the coating to achieve this. In the general thickening methods of epoxy emulsions, organically modified bentonite, fumed silica and polyurethane thickeners are generally used. To increase the low-shear viscosity, the current mainstream method is to use low-shear thickening polyurethane thickeners. However, since epoxy emulsions often contain some alcohol ether solvents, and to facilitate the film formation and curing of waterborne epoxy emulsions, an additional part of alcohol ether type film-forming co-solvents will be added. The presence of high-polarity alcohol ether solvents will reduce the thickening efficiency of low-shear polyurethane thickeners, resulting in a substantial increase in the usage amount, increasing the formulation cost. Moreover, after the usage amount is increased, due to the formation of polyurethane thickener micelles, the volume of continuous-phase water is relatively reduced, resulting in an increase in medium- and high-shear viscosities at the same time. In this way, the thixotropy index Ti value of the coating is reduced, and it becomes easier to sag. Therefore, the anti-sagging performance can only be limitedly improved by using low-shear polyurethane thickeners. In addition, the pH value of commonly used waterborne epoxy emulsions is generally in the neutral range of about 6-7, while alkali-swellable thickeners that are less affected by alcohol ether polar solvents in the system can only be effective under the condition of pH value 8-9. The organic amine compounds commonly used to adjust the pH value will react with the epoxy emulsion and cannot be used. Therefore, in some formulations, inorganic alkalis such as NaOH are used to sacrifice the water resistance and salt spray resistance of the formulation to improve the anti-sagging performance. Based on this, the present invention is proposed.

[0015] In the first aspect, the present invention provides a waterborne epoxy anti-corrosion primer, including component A and component B; wherein, by weight percentage, component A is composed of the following raw materials: deionized water I 10-30%, anti-settling agent 0.1-1%, water glass 0.1-1%, dispersant 0.5-2%, defoaming agent I 0.1-1%, pigment 5-20%, anti-rust pigment 1-15%, mica powder 1-10%, precipitated barium sulfate 5-30%, talc powder 1-15%, waterborne epoxy emulsion 25-45%, defoaming agent II 0.1-1%, wetting agent 0.1-1%, polyurethane thickener 0-2%, film-forming co-solvent 1-5%, alkali-swellable thickener 0.1-1%; component B is composed of the following raw materials: waterborne epoxy curing agent 30-65%, deionized water II 25-45%, co-solvent 5-20%, anti-flash rust agent 1-10%.

[0016] The present invention uses sodium silicate as the alkaline compound for adjusting the pH in the waterborne epoxy system. It can adjust the pH value of the system to be alkaline, enabling the alkali-swellable thickener to function, increasing the low-shear viscosity of the system, thus facilitating the improvement of the primary film thickness and obtaining a waterborne epoxy anti-corrosion primer with anti-sagging performance at a high film thickness. At the same time, due to the silicic acid structure of sodium silicate, it can undergo a self-crosslinking reaction during the film-forming process, condensing to form an inorganic polymer compound, thereby enhancing the water resistance. In addition, this pH regulator is different from traditional organic amine compounds, does not contain organic amines, and will not react with the epoxy groups in the epoxy emulsion, which is beneficial to the long-term storage stability of the waterborne epoxy primer.

[0017] In this embodiment, the waterborne epoxy emulsion can be selected from one or more of E51, E44, E20, and E12 waterborne epoxy resin emulsions. The present invention does not limit its specific brand, and those skilled in the art can make a choice according to the actual situation. For example, it can be Huntsman PZ3961-1, or Lianggu Chemical Banco 5160, Banco 5551, Banco 2091A, or Tongde 3EE104W, 2EE105W, etc.

[0018] In this embodiment, the anti-settling agent is one or more of organically modified bentonite, magnesium aluminum silicate hydrate, and fumed silica. The present invention does not limit its specific model, and those skilled in the art can make a choice according to the actual situation. For example, the model of fumed silica can be Degussa A200, A380, etc., and the brand of the bentonite anti-settling agent can be Elementis Specialties LT, EW, etc.

[0019] In this embodiment, the sodium silicate is one or more of sodium silicate (sodium water glass), potassium silicate (potassium water glass), lithium silicate (lithium water glass), and quaternary ammonium silicate water glass. The present invention does not limit its specific model, and those skilled in the art can make a choice according to the actual situation. For example, it can be GHSN, GHSK, GHSL, etc. of Jiangsu Guolian Technology Co., Ltd.

[0020] In this embodiment, the dispersant is a polymer dispersant and can be selected from one or more of modified acrylate polymer dispersants, modified polyurethane polymer dispersants, and acrylate block copolymer dispersants. The present invention does not limit its specific model, and those skilled in the art can make a choice according to the actual situation. For example, the dispersant can be the dispersant BYK190 of BYK Chemie GmbH.

[0021] In this embodiment, defoamer I and defoamer II are each independently selected from one or more of mineral oil defoamers, silicone defoamers, and polymer defoamers. The present invention does not limit their specific models, and those skilled in the art can make selections according to actual situations. For example, the models of defoamer I and defoamer II can be Degussa Tego810, Tego901W, Tego825, BYK-Chemie BYK-024, BYK-028, etc.

[0022] In this embodiment, the pigment is one or more of iron oxide red, iron oxide yellow, titanium dioxide, carbon black, and phthalocyanine blue, all of which are commercially available.

[0023] In this embodiment, the rust-inhibiting pigment is one or more of calcium ion-based rust-inhibiting pigments, zinc phosphate, and aluminum tripolyphosphate, preferably a calcium ion-based rust-inhibiting pigment, and more preferably a calcium ion-based silicate rust-inhibiting pigment. By selecting the calcium ion-based silicate rust-inhibiting pigment, the present invention can introduce active Ca with relatively weak ionicity, certain stability, and reactivity while providing corrosion resistance. 2+ When the sodium silicate film-forming and hardening, it can adsorb on the surface of polysilicic acid and shield the hydrophilic Na + , K + , Li + inside to weaken the hygroscopicity of the latter, thereby achieving the purpose of improving the water resistance of sodium silicate. At the same time, it can avoid the decrease in the storage stability of the paint caused by the reaction of overly strong active calcium ions (such as calcium oxide, calcium hydroxide, etc.) with other components in the formulation; in addition, the dehydration polymerization of the introduced silicate ions leading to changes in the ratio of SiO2 to Na2O can further improve the water resistance. It can be seen that by selecting the calcium ion-based silicate rust-inhibiting pigment, its interaction with sodium silicate can be used to reduce the negative impact of sodium silicate on water resistance, so as to achieve the reduction of the impact on the water resistance of the system while providing alkaline thickening. The present invention does not limit the specific models of the calcium ion-based silicate rust-inhibiting pigment, and those skilled in the art can make selections according to actual situations. For example, the calcium ion-based silicate rust-inhibiting pigment can be Grace AC-5, C500, or Hunan Lingwei Technology LM-30, LM-40, LM-50, etc.

[0024] In this embodiment, the mica powder is wet-processed sericite mica, a commonly commercially available product, such as Chuzhou Gerui GA-2 and GA-3 mica powder.

[0025] The present invention does not limit the specific models of precipitated barium sulfate and talc powder, which are both general commercially available products, and those skilled in the art can make selections according to actual situations.

[0026] In this embodiment, the wetting agent is a polyether silicone copolymer. The present invention does not limit its specific model, and those skilled in the art can select according to the actual situation. For example, the wetting agent can be Tego245, Tego270, Tego280, Tego Twin4100, etc. produced by Degussa in Germany.

[0027] In this embodiment, the polyurethane thickener is a polyether-type polyurethane. By adding a small amount of polyurethane thickener in the present invention, better comprehensive effects can be obtained through the compound use of the two thickeners, such as the appearance state and the flatness of the paint film, and the total amount can be reduced by using them synergistically. The present invention does not limit the specific model of the polyurethane thickener, and those skilled in the art can select according to the actual situation. For example, the polyurethane thickener can be Rheolate 299, Rheolate 288, WT-105A of Elementis Specialties, or RM-8W, RM-12W of Dow Chemical, etc.

[0028] In this embodiment, the film-forming aid is one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and benzyl alcohol.

[0029] In this embodiment, the alkali-swellable thickener is an anionic non-associative or associative alkali-swellable thickener. The present invention does not limit its specific model, and those skilled in the art can select according to the actual situation. For example, the alkali-swellable thickener can be ASE-60, TT-935 of Dow Chemical, or AS1130 of BASF, etc.

[0030] In this embodiment, the waterborne epoxy curing agent is one or more of aliphatic amines, cycloaliphatic amines, aromatic amines, and polyamides. The present invention does not limit its specific model, and those skilled in the art can select according to the actual situation. For example, the waterborne epoxy curing agent can be AD3986, AD3987, AD38-1 of Huntsman, or Banco901, Banco920, Banco928 of Allied Chemical, or 3EC153W, 3EC154W of Tongde, etc.

[0031] In this embodiment, the cosolvent is one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and benzyl alcohol.

[0032] In this embodiment, the anti-corrosion agent for flash rust is an aqueous solution of sodium nitrite or organic acid salt. The present invention does not limit its specific model, and those skilled in the art can select according to the actual situation. For example, the anti-corrosion agent for flash rust can be one or more of ASCOTECH10, H14, H18, or FA179 of Elementis Specialties.

[0033] In some preferred embodiments of the present invention, by weight percentage, the component A is composed of the following raw materials: deionized water I 20 - 30%, anti-settling agent 0.2 - 0.8%, water glass 0.1 - 0.7%, dispersant 0.5 - 1.5%, defoaming agent I 0.1 - 0.5%, pigment 5 - 15%, anti-rust pigment 3 - 7%, mica powder 2 - 6%, precipitated barium sulfate 10 - 20%, talc powder 2 - 10%, waterborne epoxy emulsion 25 - 40%, defoaming agent II 0.1 - 0.5%, wetting agent 0.1 - 0.5%, polyurethane thickener 0.1 - 1%, film-forming aid 1 - 4%, alkali-swellable thickener 0.1 - 0.6%.

[0034] In some preferred embodiments of the present invention, by weight percentage, the component B is composed of the following raw materials: waterborne epoxy curing agent 35 - 60%, deionized water II 25 - 40%, co-solvent 5 - 15%, anti-flooding and anti-rust agent 1 - 10%.

[0035] In this embodiment, the pH of the component A in the waterborne epoxy anti-corrosion primer is 8 - 9. Within this pH range, it is more conducive to the alkali-swellable thickener to play its role.

[0036] In this embodiment, the dosage ratio of the component A to the component B is (5 - 20):1, preferably (8 - 12):1, and more preferably 10:1.

[0037] In the second aspect, the present invention provides a preparation method of a waterborne epoxy anti-corrosion primer, comprising the following steps:

[0038] S1. Mix a part of deionized water I and the anti-settling agent, and mix them evenly under medium-speed dispersion. Subsequently, sequentially add water glass, dispersant, and defoaming agent I, and sequentially add pigment, anti-rust pigment, mica powder, precipitated barium sulfate, and talc powder under high-speed dispersion, and continue to disperse until uniform without particles. Grind the mixture until the fineness reaches below 40 microns, then mix it with the waterborne epoxy emulsion, and sequentially add defoaming agent II and wetting agent under medium-speed dispersion and mix evenly. Then add the pre-mixed mixture of polyurethane thickener and film-forming aid, continue to disperse evenly, and then add the pre-mixed mixture of alkali-swellable thickener and the remaining deionized water I, and mix evenly under high-speed dispersion to obtain the component A.

[0039] S2. Mix the waterborne epoxy curing agent and deionized water II, and then sequentially add the co-solvent and anti-flooding and anti-rust agent under medium-speed dispersion, and continue to disperse evenly to obtain the component B.

[0040] S3. Mix the component A and the component B evenly to obtain the waterborne epoxy anti-corrosion primer.

[0041] In this embodiment, the part of deionized water I accounts for 85 - 95% of the total mass of deionized water I.

[0042] In this embodiment, during the medium-speed dispersion process, the stirring rate is 500 - 600 rpm, and during the high-speed dispersion process, the stirring rate is 800 - 1000 rpm.

[0043] In this embodiment, a sand mill is used for grinding, and the number of grinding times is 1 - 2 times.

[0044] In some specific embodiments of the present invention, the preparation method of the above-mentioned waterborne epoxy anticorrosive primer includes the following steps:

[0045] (1) Add a part of deionized water Ⅰ into the dispersion tank, start stirring, and slowly add the anti-settling agent at 500 - 600 rpm, and disperse for 5 - 10 min until it is uniform and without lumps; add water glass, dispersant, and defoamer Ⅰ in sequence, and add pigments, anti-rust pigments, mica powder, precipitated barium sulfate, and talc powder in sequence under high-speed dispersion at 800 - 1000 rpm and disperse for 20 - 30 min until it is uniform and without particles; transfer to a sand mill and grind for 1 - 2 times until the fineness reaches below 40 microns; in another tank, add the waterborne epoxy emulsion, add the milled slurry, start stirring, and add defoamer Ⅱ and wetting agent in sequence at 500 - 600 rpm and stir for 20 - 30 min. In another small bucket, pre-mix the polyurethane thickener and film-forming auxiliary agent evenly and then slowly add them into the tank, continue to stir for 10 - 20 min, and in another small bucket, pre-mix the alkali-swellable thickener and the remaining deionized water Ⅰ evenly and then slowly add them into the tank, increase the rotation speed to 800 - 1000 rpm and continue to stir for 20 - 30 min to obtain Component A.

[0046] (2) Put the waterborne epoxy curing agent and deionized water Ⅱ into a container, and add the co-solvent and anti-flash rust agent in sequence under medium-speed stirring at 500 - 600 rpm, and continue to stir for 20 - 30 min to obtain Component B;

[0047] (3) Mix Component A and Component B evenly to obtain the waterborne epoxy anticorrosive primer.

[0048] Example 1

[0049] A preparation method of a waterborne epoxy anticorrosive primer includes the following steps:

[0050] (1) Add 23 parts of deionized water into the dispersion tank, start stirring, and slowly add 0.5 part of EW anti-settling agent at 500 rpm, and disperse for 5 min until it is uniform and without lumps.

[0051] (2) Add 0.3 part of GHSN sodium water glass, 0.8 part of BYK190 dispersant, and 0.2 part of Tego810 defoamer Ⅰ in sequence, and add 8 parts of iron oxide red pigment, 6 parts of AC-5 anti-rust pigment, 4 parts of GA-2 mica powder, 12 parts of precipitated barium sulfate, and 5 parts of talc powder in sequence under high-speed dispersion at 800 rpm and disperse for 20 min until it is uniform and without particles.

[0052] (3) Transfer to a sand mill and grind until the fineness reaches less than 40 microns.

[0053] (4) Add 35 parts of PZ3961-1 waterborne epoxy emulsion to another tank, add the sand-ground slurry, start stirring, add 0.2 parts of Tego825 defoamer II and 0.3 parts of Tego270 wetting agent in sequence at 500 rpm and stir for 20 minutes. Use another small bucket to pre-mix 0.4 parts of R299 polyurethane thickener and 2 parts of ethylene glycol butyl ether film-forming aid, then slowly add them to the tank and continue stirring for 10 minutes. Use another small bucket to pre-mix 0.3 parts of AS1130 alkali swelling thickener and 2 parts of deionized water, then slowly add them to the tank, increase the speed to 800 rpm and continue stirring for 20 minutes to obtain component A of waterborne epoxy anticorrosive primer.

[0054] (5) 37.2 parts of AD38-1 waterborne epoxy curing agent I, 12.1 parts of AD3986 waterborne epoxy curing agent II and 34.7 parts of deionized water were added into a container, and 12 parts of propylene glycol methyl ether cosolvent and 4 parts of FA179 anti-flash rust agent were added in sequence under medium speed stirring at 500 rpm. Stirring was continued for 20 minutes to obtain waterborne epoxy anticorrosive primer component B.

[0055] (6) The components A and B of the waterborne epoxy anticorrosion primer are fully mixed in a mass ratio of 10:1 to obtain the waterborne epoxy anticorrosion primer.

[0056] Comparative Example 1

[0057] (1) Add 22.3 parts of deionized water into a dispersion tank, start stirring at 500 rpm, slowly add 0.5 parts of EW anti-settling agent, and disperse for 5 minutes until it is uniform and free of lumps.

[0058] (2) 1.5 parts of BYK190 dispersant and 0.2 parts of Tego810 defoamer I were added in sequence, and 8 parts of red iron oxide pigment, 6 parts of AC-5 anti-rust pigment, 4 parts of GA-2 mica powder, 12 parts of precipitated barium sulfate, and 5 parts of talcum powder were added in sequence at 800 rpm and dispersed for 20 minutes until uniform and free of particles.

[0059] (3) Transfer to a sand mill and grind until the fineness reaches less than 40 microns.

[0060] (4) In another tank, add 35 parts of PZ3961-1 waterborne epoxy emulsion, put in the sanded slurry, start stirring, and sequentially add 0.3 parts of GHSN sodium silicate, 0.2 parts of Tego825 defoamer II, and 0.3 parts of Tego270 wetting agent at 500 rpm and stir for 20 min. In a small bucket, pre-mix 0.4 parts of R299 polyurethane thickener and 2 parts of ethylene glycol monobutyl ether film-forming aid evenly and then slowly add them to the tank. Continue stirring for 10 min. In another small bucket, pre-mix 0.3 parts of AS1130 alkali-swellable thickener and 2 parts of deionized water evenly and then slowly add them to the tank. Increase the rotation speed to 800 rpm and continue stirring for 20 min to obtain Component A of the waterborne epoxy anticorrosive primer.

[0061] (5) In a container, put in 37.2 parts of AD38-1 waterborne epoxy curing agent I, 12.1 parts of AD3986 waterborne epoxy curing agent II, and 34.7 parts of deionized water. At a medium speed of 500 rpm, sequentially add 12 parts of propylene glycol methyl ether co-solvent and 4 parts of FA179 anti-flash rust agent, and continue stirring for 20 min to obtain Component B of the waterborne epoxy anticorrosive primer.

[0062] (6) Mix Component A and Component B of the waterborne epoxy anticorrosive primer evenly according to a mass ratio of 10:1 to obtain the waterborne epoxy anticorrosive primer.

[0063] Examples 2-3 and Comparative Examples 2-3

[0064] The differences between Examples 2-3 and Comparative Examples 2-3 and Example 1 are only in the raw material dosages, as shown in Table 1 specifically.

[0065] Table 1

[0066]

[0067]

[0068] Test group

[0069] Perform performance tests on Examples 1-3 and Comparative Examples 1-3 according to the HG / T 4759-2014 Standard for Waterborne Epoxy Resin Anticorrosive Coatings. Among them, the pH value is determined according to GB1717 Determination of the pH Value of Pigment Aqueous Suspensions. The thixotropy index Ti refers to the ratio of the coating at 6 rpm and 60 rpm of the No. 4 rotor of the rotational viscometer. The rotational viscosity is determined according to the HG / T3323-2008 Method for Determining the Viscosity of Rubber Paste (Rotational Viscometer Method). The KU viscosity is detected according to the GB / T 9269-2009 Standard for Determining the Viscosity of Coatings by Stormer Viscometer Method. The sag resistance film thickness is detected according to the GB / T 9264-2012 Standard for Evaluating the Sag Resistance of Paints and Varnishes. The test results are shown in Table 2.

[0070] Table 2

[0071]

[0072] (Note: In Table 2, except for storage stability, pH value, and viscosity, the other properties are those of the waterborne epoxy anticorrosive primer.)

[0073] It can be seen from Table 2 that compared with Comparative Examples 1-3, the waterborne epoxy anticorrosive primers obtained in Examples 1-3 of the present invention all have good water resistance and salt spray resistance, and in Examples 1 and 3, after using sodium silicate and lithium silicate respectively in combination with calcium ion-based rust inhibitors, all performance indicators can meet HG / T 4759-2014 Waterborne Epoxy Resin Anticorrosive Coating.

[0074] Compared with Example 1, in Example 2, due to the increase in the amount of rust inhibitor pigment, it is beneficial to improve the salt spray resistance; at the same time, due to the increase in the amount of rust inhibitor pigment, the calcium ion content increases, so that the Ca 2+ ions react fully with the water glass and adsorb on the surface of polysilicic acid, shielding the inner hydrophilic Na + to achieve the purpose of improving water resistance; although the increase in the content of ionic rust inhibitor pigment with a large oil absorption in Example 2 leads to a certain degree of reduction in the physical and mechanical properties of the system, it can still meet the performance requirements of certain specific scenarios with high requirements for water resistance and salt spray resistance.

[0075] Compared with Example 1, in Example 3, since lithium silicate made of lithium with a smaller atomic radius is used, it is not easily dissolved by hydrophilic substances after being shielded by calcium ions, significantly improving the water resistance and salt spray resistance, and at the same time also improving the adhesion and impact resistance, but the price of lithium silicate is much higher than that of sodium silicate.

[0076] In addition, the inventors found during the experiment that when using the method of adding water glass later to adjust the pH value, the viscosity will increase significantly during the sanding stage, making it difficult to sand and disperse, resulting in a significant decrease in both the water resistance and salt spray test results. It can be seen that adding water glass in the early stage also has a certain function of dispersing and reducing viscosity, which can save the amount of dispersant. Compared with Example 1, in Comparative Example 1, the method of adding sodium silicate later to adjust the pH value was adopted, and the amount of dispersant BYK190 was increased to reduce the viscosity. Due to the increase in the amount of dispersant, the pigment was fully wrapped and wetted, thereby improving the adhesion and impact resistance; however, since the dispersant BYK190 is a surfactant containing lipophilic and hydrophilic groups, at a certain addition amount, it has little effect on water resistance, but as the amount increases, more hydrophilic groups are introduced, increasing the hydrophilicity and causing a significant decrease in water resistance.

[0077] Compared with Example 1, in Comparative Example 2, since the conventional anti-rust pigment zinc phosphate without active calcium ions is used, it cannot effectively react with the polysilicic acid of sodium silicate, or the reaction degree is low. Therefore, the water resistance and salt spray resistance are significantly reduced. However, due to the lower oil absorption of the zinc phosphate anti-rust pigment, it will significantly promote the improvement of adhesion and impact resistance.

[0078] Compared with Example 1, in Comparative Example 3, since the amount of sodium silicate is increased, the pH value of the system is significantly increased, the system becomes unstable, and a large amount of hydrophilic Na + ions do not have sufficient active Ca 2+ ions to shield them, and the water resistance and salt spray resistance are significantly reduced.

[0079] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. An aqueous epoxy anti-corrosion primer, characterized in that, It includes Component A and Component B; among them, by weight percentage, Component A is composed of the following raw materials: deionized water I 10 - 30%, anti-settling agent 0.1 - 1%, water glass 0.1 - 1%, dispersant 0.5 - 2%, defoaming agent I 0.1 - 1%, pigment 5 - 20%, anti-rust pigment 1 - 15%, mica powder 1 - 10%, precipitated barium sulfate 5 - 30%, talc powder 1 - 15%, waterborne epoxy emulsion 25 - 45%, defoaming agent II 0.1 - 1%, wetting agent 0.1 - 1%, polyurethane thickener 0 - 2%, film-forming aid 1 - 5%, alkali-swellable thickener 0.1 - 1%; Component B is composed of the following raw materials: waterborne epoxy curing agent 30 - 65%, deionized water II 25 - 45%, co-solvent 5 - 20%, anti-flooding and rusting agent 1 - 10%; among them, The water glass is one or more of sodium silicate, potassium silicate, lithium silicate, and quaternary ammonium silicate water glass. The anti-rust pigment is a calcium ion type silicate anti-rust pigment.

2. The waterborne epoxy anticorrosive primer according to claim 1, wherein The waterborne epoxy emulsion is one or more of E51, E44, E20, and E12 waterborne epoxy resin emulsions; the anti-settling agent is one or more of organically modified bentonite, magnesium aluminum silicate hydrate, and fumed silica; the dispersant is a polymer dispersant; Defoaming agent I and defoaming agent II are respectively selected from one or more of mineral oil defoaming agents and silicone defoaming agents; the pigment is one or more of iron oxide red, iron oxide yellow, titanium dioxide, carbon black, and phthalocyanine blue; the wetting agent is a polyether silicone copolymer; the polyurethane thickener is a polyether type polyurethane; the film-forming aid is one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and benzyl alcohol; the alkali-swellable thickener is an anionic non-associated or associated alkali-swellable thickener.

3. The waterborne epoxy anticorrosive primer according to claim 1, wherein The waterborne epoxy curing agent is one or more of aliphatic amines, cycloaliphatic amines, aromatic amines, and polyamides; the co-solvent is one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and benzyl alcohol; the anti-flooding and rusting agent is an aqueous solution of sodium nitrite or organic acid salt.

4. The waterborne epoxy anti-corrosion primer according to claim 1, characterized in that, By weight percentage, Component A is composed of the following raw materials: deionized water I 20 - 30%, anti-settling agent 0.2 - 0.8%, water glass 0.1 - 0.7%, dispersant 0.5 - 1.5%, defoaming agent I 0.1 - 0.5%, pigment 5 - 15%, anti-rust pigment 3 - 7%, mica powder 2 - 6%, precipitated barium sulfate 10 - 20%, talc powder 2 - 10%, waterborne epoxy emulsion 25 - 40%, defoaming agent II 0.1 - 0.5%, wetting agent 0.1 - 0.5%, polyurethane thickener 0.1 - 1%, film-forming aid 1 - 4%, alkali-swellable thickener 0.1 - 0.6%; Component B is composed of the following raw materials: waterborne epoxy curing agent 35 - 60%, deionized water II 25 - 40%, co-solvent 5 - 15%, anti-flooding and rusting agent 1 - 10%.

5. The waterborne epoxy anticorrosive primer according to claim 1, characterized in that, In the waterborne epoxy anti-corrosion primer, the pH of Component A is 8 - 9.

6. The waterborne epoxy anti-corrosion primer according to claim 1, characterized in that, The dosage ratio of the component A to the component B is (5 - 20):

1.

7. A preparation method of the waterborne epoxy anticorrosive primer according to any one of claims 1-6, characterized in that, It includes the following steps: Mix a part of deionized water I with the anti-settling agent and mix them evenly under medium-speed dispersion. Subsequently, add sodium silicate, the dispersant, and the defoamer I in sequence, and add the pigment, the anti-rust pigment, mica powder, precipitated barium sulfate, and talc powder under high-speed dispersion in sequence. Continue to disperse until it is uniform and free of particles. Grind the mixture until the fineness reaches below 40 microns, then mix it with the waterborne epoxy emulsion, and add the defoamer II and the wetting agent in sequence under medium-speed dispersion and mix them evenly. Then add the mixture of the pre-mixed polyurethane thickener and the film-forming aid, continue to disperse evenly, and then add the mixture of the pre-mixed alkali-swellable thickener and the remaining deionized water I, and mix them evenly under high-speed dispersion to obtain the component A; Mix the waterborne epoxy curing agent with deionized water II, and then add the co-solvent and the anti-flash rust agent in sequence under medium-speed dispersion. After continuing to disperse evenly, obtain the component B; Mix the component A and the component B evenly to obtain the waterborne epoxy anti-corrosion primer.

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