Double-crosslinking type water-based single-component anticorrosive paint and preparation method thereof

Abstract

The invention provides a double-crosslinking type water-based single-component anticorrosive coating. The double-crosslinking type water-based single-component anticorrosive coating comprises the following components in parts by weight: 35-60 parts of self-crosslinking acrylic emulsion and 5-10 parts of water-based alkyd resin, 10-30 parts of a functional pigment filler, 0.3-5 parts of a functional auxiliary agent and 1-8 parts of a cosolvent; the solid mass ratio of the self-crosslinking acrylic emulsion to the water-based alkyd resin is (10-2.5): 1. The double-crosslinking water-based single-component anticorrosive paint with excellent performance is prepared by adopting high-performance water-based resin compound, functional pigment filler, auxiliaries and a small amount of solvent, crosslinking points in a system are increased, the compatibility between resins is improved, the stability of the paint is improved, and then the comprehensive performance of the paint after curing is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a double-crosslinked water-based single-component anticorrosive coating and a preparation method thereof. Background Art

[0002] With the continuous improvement of environmental protection regulations, water-based single-component coatings, as a type of green coatings with low VOC and easy construction, are gradually favored by the market in the fields of light anti-corrosion steel structures such as industrial plants, pipelines, mechanical equipment, highway guardrails and automotive parts. These application fields require water-based single-component coatings to have certain anti-corrosion properties. At the same time, they have a high construction tolerance on steel structure surfaces with welds and low surface treatment, as well as in construction environments without temperature and humidity control.

[0003] Acrylic paint, alkyd paint and epoxy ester paint are typical representatives of water-based single-component anti-corrosion paint. The film formation of water-based acrylic paint can be divided into three stages: water evaporation, latex particle aggregation, and latex particle fusion. The process mainly involves physical cross-linking. Water-based acrylic paint has the characteristics of low odor, fast drying speed, excellent weather resistance, etc., which can improve production efficiency, but has high requirements for substrate pretreatment and construction environment temperature and humidity control. It is prone to "flash rust", becomes brittle when cold, and becomes sticky when hot. Extreme climate changes can easily cause the paint film to crack and fall off; during the film formation process of water-based alkyd paint, the unsaturated double bonds will react with oxygen in the air to form a paint film with a chemical cross-linked structure. Water-based alkyd paint has good wettability and permeability, and the paint film is full and has excellent leveling properties, but it dries slowly and takes a long time to build hardness. In addition, the ester bonds in water-based alkyd resins are easily hydrolyzed in water, resulting in poor storage stability of the paint, affecting its use. Water-based epoxy ester paint has outstanding anti-corrosion properties, but poor weather resistance, and its application is greatly limited in environments with direct sunlight.

[0004] To sum up, the three types of water-based one-component coatings have their own advantages and disadvantages due to the differences in their resin components: water-based acrylic emulsion, water-based alkyd resin, and water-based epoxy ester resin: water-based acrylic resin usually has a higher molecular weight and Tg, and its film-forming method is mainly through solvent volatilization, so it dries quickly and has excellent weather resistance, but its anti-rust performance and leveling properties are poor; while the molecular weight and Tg of water-based alkyd resin are relatively low, its leveling property is good, and it is accompanied by oxidative cross-linking film formation, which can effectively alleviate the "flash rust" phenomenon, but its general drying speed is slow, affecting the construction progress, and its weather resistance is relatively poor; the film-forming method of water-based epoxy ester resin is similar to that of water-based alkyd resin. Due to the presence of epoxy groups, it provides the coating with excellent adhesion and anti-corrosion properties, but its weather resistance is greatly reduced. The construction tolerance of coatings of different systems can be improved by simply adding functional additives. However, since the additives in water-based coatings are mostly amphiphilic compounds, improper use will not only increase the complexity of the coating formula, but will also easily affect the stability of the coating and the performance of the paint film, causing quality risks and affecting the service life and safety of steel. Summary of the invention

[0005] In order to ensure the quality of coating, the present invention provides a double-crosslinked water-based single-component anti-corrosion coating and a preparation method thereof. High-performance water-based resin compound, functional pigments and fillers, additives and a small amount of solvent are used to prepare a double-crosslinked water-based single-component anti-corrosion coating with excellent performance, increase the crosslinking points in the system, improve the compatibility between resins, improve the stability of the coating, and thereby improve the comprehensive performance of the coating after curing.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A double-crosslinked water-based single-component anticorrosive coating, comprising the following components by weight: 35-60 parts of self-crosslinking acrylic emulsion, 5-10 parts of water-based alkyd resin; 10-30 parts of functional pigments and fillers, 0.3-5 parts of functional additives, and 1-8 parts of cosolvents;

[0008] The self-crosslinking acrylic emulsion has a functional group on the molecular chain that can be crosslinked with a carboxyl group, and the solid mass ratio of the self-crosslinking acrylic emulsion to the water-based alkyd resin is 10-2.5:1.

[0009] Preferably, the solid mass ratio of the self-crosslinking acrylic emulsion to the waterborne alkyd resin is 10-5:1.

[0010] Preferably, the solid mass ratio of the self-crosslinking acrylic emulsion to the waterborne alkyd resin is 4.9-5.1:1.

[0011] Preferably, the self-crosslinking acrylic emulsion is a self-crosslinking acrylic emulsion of adipic acid dihydrazide or carboimide crosslinking system, which can increase the crosslinking density of the coating and improve the mechanical strength and water resistance of the paint film while contributing excellent drying properties, anti-sagging properties and weather resistance.

[0012] Preferably, the waterborne alkyd resin is a self-drying medium- and long-oil waterborne alkyd resin and a modified waterborne alkyd resin thereof, which can not only enhance the initial anticorrosive performance of the paint film, but also improve the gloss and fullness of the paint film.

[0013] Preferably, the functional pigments and fillers include any mixture of coloring pigments (such as titanium dioxide, phthalocyanine blue, carbon black, etc., and toner is selected according to the agreed color requirements), anti-rust pigments (such as phosphate series and silica series, etc.), functional fillers (such as mica powder and talc powder, etc.) or fillers (calcium carbonate and barium sulfate, etc.), and the mass proportion of the anti-rust pigment in the functional pigments and fillers is 30-40%. When the mass proportion of the anti-rust pigment in the functional pigments and fillers is 30-40%, it can ensure the anti-corrosion function while also ensuring low cost and gloss after the coating is cured.

[0014] Preferably, the functional additive includes any one of an anti-settling agent, a defoaming agent, a dispersant, an anti-flash rust agent, a thickener, a wetting agent, a film-forming aid or a pH adjuster (N,N-dimethylethanolamine, DMEA) or a mixture of several thereof, and the solvent includes ethylene glycol butyl ether.

[0015] Based on the same inventive concept, the present invention also provides a double-crosslinked water-based one-component anti-corrosion coating, comprising the following steps:

[0016] S1: Prepare slurry: add deionized water to a mixing drum, add bentonite under low-speed stirring at 300-500rpm, increase the speed to 1000-1500rpm for high-speed dispersion for 15-20min; then slowly add: cosolvent, pH adjuster, dispersant, defoamer in sequence, disperse for 4-6min, reduce the speed to 500rpm for low-speed stirring, slowly add coloring pigment (pigment selected according to agreed color requirements), anti-rust pigment, 30-60g functional filler (such as mica powder or talcum powder) and filler (such as precipitated barium sulfate) in sequence, increase the speed to 1500-2500rpm for stirring and pre-dispersion, transfer to a sand mill for grinding after 25-35min, grind to a fineness equal to or less than 30μm, filter out for use;

[0017] S2: Emulsified water-based alkyd resin: Add water-based alkyd resin to a plastic container, place the disperser in place, stir at a low speed of 290-310 rpm, add the cosolvent, disperse at a low speed for 4-6 minutes, slowly add deionized water several times, increase the speed to 500-800 rpm, stir for 10-20 minutes, slowly add the drying agent in sequence, maintain the speed of 700-900 rpm for 15-25 minutes until the dispersion is uniform, and then take out for use;

[0018] S3: paint mixing: mix the self-crosslinking acrylic emulsion, the emulsified water-based alkyd resin, and the slurry of step S1, and add an anti-rust agent, a wetting agent, and a film-forming aid, stir evenly, and adjust the pH value to 8-9 with a pH regulator, adjust the solid content to 40%-50% with deionized water, and adjust the viscosity to 80-100s with a thickener to obtain the anti-corrosion coating.

[0019] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0020] In the present application, a blend of self-crosslinking acrylic emulsion and water-based alkyd resin is used as the film-forming substance. The self-crosslinking acrylic emulsion has functional groups that can crosslink with acrylic acid and carboxylic acid in alkyd, which improves the crosslinking degree of the resin system, improves the compatibility between resins, and improves the storage stability of the coating. Moreover, the resin system is mainly composed of self-crosslinking acrylic emulsion, and a small amount of water-based alkyd resin is added, which can retain the fast drying speed, anti-sagging performance, hardness, and weather resistance of the self-crosslinking acrylic, and also has anti-corrosion and anti-flashing properties.

[0021] Therefore, the anti-corrosion coating provided by the present invention achieves a high construction tolerance of water-based single-component coatings. Compared with the method of adding functional additives in the prior art, the stability risk caused by the impact of additives on the system is reduced, and the occurrence of situations such as the additive system becoming complicated is avoided; under the designed ratio of self-crosslinking acrylic emulsion and water-based alkyd, the respective advantages are retained and the amplification of disadvantages is avoided. At the same time, the crosslinking density of traditional single-component coatings is improved, and the bonding strength between the coating and the substrate is further improved, so that the coating performance is maximized; by adjusting the ratio of functional pigments and fillers, the paint film is made denser, ensuring that the functional pigments and fillers fully release their activity, so as to extend the service life of the steel structure material, and also reduce the coating cost. DETAILED DESCRIPTION

[0022] Water-based single-component coatings represented by acrylic paint, alkyd paint and epoxy ester paint have their own advantages and disadvantages, but the water-based single-component anti-corrosion paints on the market generally have a narrow construction window. When dealing with different pre-treatment processes, spraying equipment and spraying environments, they need to add functional additives to adapt to the construction environment, which not only affects production efficiency, but also leads to large fluctuations in product quality. In addition, the addition of additives makes the formula structure and production process more complicated, and the matching with the system requires a large number of experiments and strict evaluations. Improper use often causes coarsening, stratification and even gelation, which affects the storage stability of the coating.

[0023] The present invention compounds the self-crosslinking acrylic emulsion and the water-based alkyd, increases the crosslinking points in the system, improves the compatibility between the resins, and through a suitable ratio, not only does it not reduce the shortcomings of acrylic paint due to the introduction of alkyd, but it can also retain the advantages of acrylic and alkyd, avoiding the amplification of the shortcomings; by combining the characteristics of different types of resins, optimizing the structure of film-forming materials, broadening the construction tolerance, reducing the dependence on additives, solving the limitations of the single resin system coating construction, achieving both wetting and leveling properties and drying properties, and can adapt to more application scenarios. At the same time, the crosslinking density in the system is improved, and the bonding force between the coating and the substrate is further improved, so that the coating performance after the coating is cured is reflected to the greatest extent.

[0024] The following is a further detailed description of a double cross-linked waterborne one-component anticorrosive coating and a preparation method thereof proposed by the present invention in conjunction with specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0025] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0026] The water-based alkyd resin and water-based self-crosslinking acrylic emulsion used in the following examples are from Jinlitai Company.

[0027] Example 1

[0028] A double-crosslinked water-based single-component anticorrosive coating includes the following components calculated by weight: self-crosslinking acrylic emulsion, water-based alkyd resin, functional filler, additives, and solvent. The preparation method adopts the following steps:

[0029] S1: Preparation of slurry

[0030] Add pure water to a 1.5L stainless steel barrel in sequence, place the disperser in place, slowly add CLIMINTON LB bentonite under low-speed stirring at 500rpm, increase the speed to 1500rpm for high-speed dispersion for 15min, restore the speed to 500rpm, slowly add ethylene glycol butyl ether, DMEA, gTego755W dispersant, Foam Star ST 2410AG defoamer, R-996 titanium dioxide, 8631 phthalocyanine blue, ZPA anti-rust pigment, mica powder, precipitated barium sulfate in sequence, increase the speed to 2000rpm for pre-dispersion, take out after 30min, transfer to a grinding barrel, pass cooling water, add glass beads, increase the speed to 2500rpm, grind to a fineness of 30μm, filter out for use;

[0031] S2: Emulsified waterborne alkyd resin

[0032] Add 3R5014P water-based alkyd resin made by Jinlitai Company into a 500ml plastic container, place the disperser in place, and stir at a low speed of 300rpm. Then add ethylene glycol butyl ether, disperse at a low speed for 5 minutes, slowly add pure water several times, increase the speed to 500-800rpm, stir for 15 minutes, and slowly add QD25 drying agent of Guangdong Qirun Company in sequence, maintain the speed of 800rpm for 20 minutes until it is evenly dispersed, and then take it out for use;

[0033] S3: Paint mixing

[0034] Add 3R6224S water-based self-crosslinking acrylic emulsion produced by Jinlitai Company to a 1L plastic container, place it in a disperser and fix it, stir it at a low speed of 500rpm, slowly add the water-based alkyd resin dispersion in step S2, the slurry in step S1, Coadd FR3100 flash rust inhibitor produced by Puwei Additives Company, Coadd W118 substrate wetting agent produced by Puwei Additives Company, and then add Eastman's Texanol film-forming agent, adjust the pH value to 8-9 with DMEA, adjust the solid content to 45%-50% with water, adjust the coating viscosity to 80-100s (apply 4 cups @25°C) with XS 71 thickener produced by Gaotai Company, take it out, and test the construction performance and physical and chemical properties of the paint film.

[0035] The anti-corrosion coating prepared according to the above method, the required raw materials are weighed according to Table 1.

[0036] Table 1

[0037]

[0038]

[0039] After the above comparative examples and embodiments are prepared, the coatings prepared above are tested using the test standards in Table 2:

[0040]

[0041] The results are shown in Table 3:

[0042]

[0043]

[0044] From the data in Table 3, it can be concluded that when the solid mass ratio of the self-crosslinking acrylic emulsion to the water-based alkyd is between 10-2.5:1, a coating with comprehensive workability and physical and chemical properties of the paint film can be obtained. Furthermore, when the solid mass ratio of the self-crosslinking acrylic emulsion to the water-based alkyd is 10-5:1, the comprehensive performance is more prominent, and further preferably 5:1.

[0045] The solid mass ratio of the self-crosslinking acrylic emulsion to the water-based alkyd in Example 3 was retained at 5:1, and the mass ratio of the anti-rust pigment to the functional pigment filler was changed. The coating was prepared in the same manner as in Example 3. The proportions of the raw materials in each example and comparative example are shown in Table 4:

[0046]

[0047]

[0048] The gloss, water resistance and salt spray resistance of the examples and comparative examples shown in Table 4 were tested, and the results are shown in Table 5:

[0049]

[0050] From the test results in Table 5, it can be seen that when the proportion of anti-rust pigment in the powder is 30-50%, excellent salt spray resistance and water resistance can be obtained, and when the proportion of anti-rust pigment in the powder is 30-40%, excellent gloss performance can be obtained while taking into account the coating cost.

[0051] Therefore, the present invention combines the cross-linking mechanism of self-cross-linking acrylic emulsion and water-based alkyd, retains their respective advantages under the designed ratio, avoids the amplification of disadvantages, and improves the cross-linking density of the resin, improves the compatibility between the resins, and thus improves the stability of the coating; and by adjusting the ratio of functional pigments and fillers, the paint film is made denser, ensuring that the functional pigments and fillers fully release their activity to extend the service life of the substrate. In addition, the coating of the present invention reduces its dependence on additives, solves the limitations of the single resin system coating during construction, achieves both wetting and leveling properties and drying properties, and can adapt to more application scenarios.

[0052] The above is a detailed description of the implementation of the present invention in conjunction with specific embodiments, but the present invention is not limited to the above implementation. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A double-crosslinked water-based one-component anticorrosive coating, characterized in that: The composition includes the following components by weight: 35-60 parts of self-crosslinking acrylic emulsion, 5-10 parts of water-based alkyd resin, 10-30 parts of functional pigments and fillers, 0.3-5 parts of functional additives, and 1-8 parts of cosolvents; The self-crosslinking acrylic emulsion has a functional group on the molecular chain that can be crosslinked with a carboxyl group, and the solid mass ratio of the self-crosslinking acrylic emulsion to the water-based alkyd resin is 10-2.5:

1.

2. The double-crosslinked water-based one-component anticorrosive coating according to claim 1, characterized in that: The solid mass ratio of the self-crosslinking acrylic emulsion to the waterborne alkyd resin is 10-5:

1.

3. The double-crosslinked water-based one-component anticorrosive coating according to claim 2, characterized in that: The solid mass ratio of the self-crosslinking acrylic emulsion to the waterborne alkyd resin is 4.9-5.1:

1.

4. The double-crosslinked water-based one-component anticorrosive coating according to claim 1 or 2, characterized in that: The self-crosslinking acrylic emulsion is a self-crosslinking acrylic emulsion of adipic acid dihydrazide or carboimide crosslinking system.

5. The double-crosslinked water-based one-component anticorrosive coating according to claim 1, characterized in that: The waterborne alkyd resin is a self-drying medium- and long-oil waterborne alkyd resin and a modified waterborne alkyd resin thereof.

6. The double-crosslinked water-based one-component anticorrosive coating according to claim 1, characterized in that: The functional pigments and fillers include coloring pigments, anti-rust pigments, functional fillers or a mixture of several of the fillers, and the anti-rust pigment accounts for 30-40% of the weight of the functional pigments and fillers.

7. The double-crosslinked water-based one-component anticorrosive coating according to claim 1, characterized in that: The functional additives include any one of an anti-settling agent, a pH regulator, a defoamer, a dispersant, an anti-flash rust agent, a thickener, a wetting agent or a film-forming aid or a mixture of several of them, and the cosolvent includes ethylene glycol butyl ether.

8. A double-crosslinked water-based one-component anticorrosive coating, characterized in that: The following steps are involved: S1: Prepare slurry: add deionized water to a mixing drum, add bentonite under low-speed stirring at 300-500rpm, increase the speed to 1000-2000rpm for high-speed dispersion for 15-20min; then slowly add: cosolvent, pH adjuster, dispersant, defoamer in sequence, disperse for 4-6min, reduce the speed to 500rpm for low-speed stirring, slowly add coloring pigment, anti-rust pigment, functional filler and filler in sequence, increase the speed to 1500-2500rpm for stirring and pre-dispersion, transfer to a sand mill for grinding after 25-35min, grind to a fineness equal to or less than 30μm, filter out for use; S2: Emulsified water-based alkyd resin: Add water-based alkyd resin to a plastic container, place the disperser in place, stir at a low speed of 290-310 rpm, add the cosolvent, disperse at a low speed for 4-6 minutes, slowly add deionized water several times, increase the speed to 500-800 rpm, stir for 10-20 minutes, slowly add the drying agent in sequence, maintain the speed of 700-900 rpm for 15-25 minutes until the dispersion is uniform, and then take out for use; S3: paint mixing: mix the self-crosslinking acrylic emulsion, the emulsified water-based alkyd resin, and the slurry of step S1, and add an anti-rust agent, a wetting agent, and a film-forming aid, stir evenly, and adjust the pH value to 8-9 with a pH regulator, adjust the solid content to 40%-50% with deionized water, and adjust the viscosity to 80-100s with a thickener to obtain the anti-corrosion coating.

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