An aqueous primer, its preparation method and application

Abstract

The present invention provides an aqueous primer, a preparation method thereof and an application. In the present invention, hydrotalcite and an alcohol ether-based polar organic compound are added to the B component containing zinc powder, and the hydrotalcite loaded with the alcohol ether-based polar organic compound is grafted onto the surface of the zinc powder under the action of a silane coupling agent. When mixed, it acts together with the aqueous elastic emulsion in the A component, significantly improving the corrosion resistance and weather resistance of the paint film, and also improving the sprayability of the primer and the drying time of the paint film.

Description

Technical Field

[0001] The present invention relates to the technical field of waterborne coatings, in particular to a waterborne primer, a preparation method thereof and an application thereof. Background Art

[0002] Shop primer, also known as pretreatment primer or maintenance primer, is a pretreatment primer sprayed on the metal surface on the workshop assembly line after the steel is sandblasted to remove rust, so as to prevent the steel from rusting during storage, processing and other processes. The main varieties of shop primer are PVB, epoxy zinc-rich, epoxy iron oxide red and inorganic zinc silicate, etc. Solvent-based inorganic zinc silicate shop primer is a widely used shop primer at present due to its excellent drying property, outdoor corrosion resistance and high temperature resistance, etc. However, its volume solids content is low, and the VOC content exceeds 420 g / L, which belongs to dangerous chemicals and seriously harms the environment and affects human safety.

[0003] Waterborne shop primer is considered an effective substitute for solvent-based primer due to its excellent environmental protection performance and workability. However, the current waterborne shop primer has poor drying performance, generally higher than 5 minutes, and poor outdoor corrosion resistance (weather resistance), and it is difficult to reach 6 months or even 12 months; in addition, there is still a certain gap between the existing waterborne shop primer's resistance to welding and cutting and that of solvent-based primer, thus affecting the construction rhythm and efficiency on site. Therefore, further improvement is needed to meet the on-site use requirements.

[0004] In addition, due to the conventional silicate resin used in the currently common waterborne shop primer, its viscosity is relatively low, and it is easy to cause gun clogging and other phenomena during the spraying process, and its spraying performance is poor. The uneven spraying also leads to the corrosion resistance and weather resistance still to be improved. In order to improve its processing performance and corrosion resistance, Patent CN102485806A stores the zinc powder-containing base material and the waterborne film-forming component of the curing agent separately, and adds a heterocyclic organic compound to the zinc powder-containing base material component, which acts together with the surfactant to coat the zinc powder to avoid direct contact between the zinc powder and the aqueous medium; when the base material and the curing agent are mixed, the protective film on the surface of the zinc powder can be opened, and spraying can be carried out smoothly. However, the heterocyclic organic compound has poor compatibility with the aqueous medium. After the coated zinc powder is mixed with the curing agent component, it is easy to cause uneven dispersion of the zinc powder in the primer component, thereby hindering the further improvement of the corrosion resistance and weather resistance of the paint film. In addition, its compatibility with other paint films (such as epoxy paint) is poor, seriously affecting the construction of subsequent coatings.

[0005] Therefore, how to improve the processing performance, weather resistance and compatibility of waterborne shop primer is an important problem that urgently needs to be solved. Summary of the Invention

[0006] The object of the present invention is to solve the defect that the existing waterborne shop primer has poor comprehensive performance, and to provide a waterborne primer with excellent comprehensive performance. The waterborne primer of the present invention has excellent drying time, weather resistance, welding and cutting performance, and at the same time has excellent compatibility and workability.

[0007] Another object of the present invention is to provide a preparation method of the waterborne primer.

[0008] Another object of the present invention is to provide an application of the waterborne primer in manufacturing ships, bridges or mechanical equipment.

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

[0010] A waterborne primer, comprising the following components in parts by weight:

[0011] Component A, with a total weight of 50 parts:

[0012]

[0013] Component B, with a total weight of 50 parts:

[0014]

[0015] The zinc powder includes spherical zinc powder and flaky zinc powder;

[0016] Among them, the preparation method of Component B includes the following steps:

[0017] S1. Premixing: Mix the alcohol ether-based polar organic compound, silane coupling agent and absolute ethanol evenly to obtain a premix;

[0018] S2. Add anti-settling agent B to the premix obtained in step S1 and mix evenly, then add hydrotalcite, zinc powder and anti-rust pigment in sequence and mix evenly to obtain Component B.

[0019] In the present invention, hydrotalcite and alcohol ether-based polar organic compounds are added to the B component containing zinc powder. Hydrotalcite belongs to anionic layered compounds, which are porous materials and multi-layer materials and have an ion exchange function at the same time. For example, when chloride ions corrode the base material, some anions in the layer, such as phosphate ions and molybdate ions, can undergo ion exchange with them to fix the chloride ions, release phosphate ions and molybdate ions to protect the base material. The anti-rust pigments in the primer can supplement the lacking anions such as phosphate ions and molybdate ions for hydrotalcite, having a further synergistic effect; in addition, the porous structure can effectively adsorb alcohol ether-based polar organic compounds, load the alcohol ether-based polar organic compounds into hydrotalcite, and the loaded alcohol ether-based polar organic compounds can be used as lubricants or solvents to promote the further grafting of silane coupling agents onto the surfaces of zinc powder and hydrotalcite to form a kind of three-dimensional network-like structure, increasing the sealing property, barrier effect and adhesion ability of the system, and further improving the anti-corrosion ability of the whole system.

[0020] During spraying construction, when the B component containing zinc powder is mixed with the water-based A component, the three-dimensional network-like structure in the system has a certain slow-release protection effect on zinc powder, avoiding the direct contact reaction between active zinc powder and water-based components to form precipitation, which is beneficial to improving the stability of the primer system; and the alcohol ether-based polar organic compounds loaded in hydrotalcite have good compatibility with water-based raw materials, and can also improve the dispersion uniformity of inorganic zinc powder in the primer system, improving the corrosion resistance and weather resistance of the paint film; in addition, suitable alcohol ether-based polar organic compounds can also cause the elastic emulsion to swell. While increasing the viscosity of the mixed primer system, it can reduce the surface tension of the system, not only effectively improving the dispersion stability of inorganic fillers (such as zinc powder, hydrotalcite, anti-rust pigments) in the system to prevent their precipitation, but also forming a "co-solvent" with water to increase the evaporation rate of water, further shortening the drying time of the water-based primer.

[0021] Preferably, the alcohol ether-based polar organic compounds include, but are not limited to, one or a combination of several of propylene glycol methyl ether, dipropylene glycol methyl ether or ethylene glycol propyl ether, and further preferably propylene glycol methyl ether. The alcohol ether-based polar organic compounds can be used as solvents, having high polarity and improving the dispersion of zinc powder in the water-based primer system.

[0022] Preferably, the zinc powder includes spherical zinc powder and flaky zinc powder, and the weight ratio of the spherical zinc powder to the flaky zinc powder is spherical zinc powder: flaky zinc powder = (1 - 6): 1. The spherical zinc powder and the flaky zinc powder are mixed, which can improve the compactness of the zinc powder in the paint film on the surface of the base material while effectively utilizing the barrier effect of the flaky zinc powder, further improving the corrosion resistance and weather resistance of the paint film.

[0023] Preferably, the anti-rust pigment includes one or a combination of several of zinc phosphate, micaceous iron oxide, aluminum tripolyphosphate, lithium silicate, and iron phosphate powder. The addition of the anti-rust pigment can further improve the corrosion resistance and weather resistance of the paint film.

[0024] Preferably, the particle size of the hydrotalcite is < 30 μm. Within this range, the particle size of the hydrotalcite can further enhance the anti-corrosion performance, leveling property, and high-temperature resistance of the paint film.

[0025] Preferably, the water-based inorganic resin includes one or a combination of several of potassium silicate, lithium silicate, sodium silicate, or silica sol.

[0026] Preferably, the elastic emulsion includes one or a combination of several of styrene-acrylic emulsion, silicone-acrylic emulsion, and acrylic emulsion.

[0027] Preferably, the anti-settling agent A includes one or a combination of several of polyurethane, associative acrylic acid, and polyamide wax.

[0028] Preferably, the anti-settling agent B includes one or a combination of several of nano-montmorillonite, organic bentonite, and fumed silica.

[0029] Preferably, the dispersant includes one or a combination of several of polyether compounds, acrylic polymers, and phosphate ester compounds.

[0030] Preferably, the defoamer includes one or a combination of several of silicone defoamers, polyether defoamers, and mineral oil defoamers.

[0031] Preferably, the silane coupling agent includes one or a combination of several of amino silanes and epoxy silanes.

[0032] The preparation method of the water-based primer includes the following steps:

[0033] Preparation of component A:

[0034] S1. Premixing: Mix the elastic emulsion, dispersant, and water evenly to obtain a premix;

[0035] S2. After adding the anti-settling agent A to the premix obtained in step S1 and mixing evenly, continue to add the water-based inorganic resin, dispersant, defoamer, and leveling agent and mix evenly to obtain component A;

[0036] Preparation of component B:

[0037] S1. Premixing: Mix the alcohol ether-based polar organic compound, silane coupling agent, and absolute ethanol evenly to obtain a premix;

[0038] S2. After adding anti-settling agent B to the premix obtained in step S1 and mixing evenly, hydrotalcite, zinc powder and anti-rust pigment are added in sequence and mixed evenly to obtain component B.

[0039] By using the method of the present invention, hydrotalcite grafted and loaded with alcohol ether-based polar organic compounds on the surface of zinc powder in component B can act together with the elastic emulsion in component A, which can significantly improve the corrosion resistance, weather resistance and processing performance of the paint film.

[0040] In the present invention, common mixing methods can be used in the preparation of the above-mentioned waterborne primer. For example, stirring. According to the dispersion difficulty of different raw materials, the stirring speed can be selected within the range of 300-2500 r / min, and the raw materials can be mixed evenly. The required time is generally within the range of 10-30 min.

[0041] The application of the above-mentioned waterborne primer in manufacturing ships, bridges or mechanical equipment is also within the protection scope of the present invention.

[0042] When the waterborne primer of the present invention is used, component A and component B need to be mixed and then sprayed with a spray gun (such as automatic high-pressure airless spraying). Among them, the weight ratio of component A and component B is mixed according to the ratio of A:B = 1:(1-5), and the comprehensive performance of the paint film after filming is better.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] By adding hydrotalcite and alcohol ether-based polar organic compounds to component B containing zinc powder, and grafting hydrotalcite loaded with alcohol ether-based polar organic compounds onto the surface of zinc powder under the action of silane coupling agent, when mixing, it acts together with the elastic emulsion in component A, significantly improving the corrosion resistance and weather resistance of the paint film, and also improving the sprayability of the primer and the drying time of the paint film. Specific Embodiments

[0045] To better illustrate the purpose, technical solution and advantages of the present invention, the following specific embodiments will be used to further illustrate the present invention, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field. Unless otherwise specified, the reagents and materials used in the present invention are all commercially available.

[0046] The following raw materials are selected in the embodiments of the present invention:

[0047] Waterborne inorganic resin-1: inorganic silicate, G36, purchased from Anhui Cima;

[0048] Waterborne inorganic resin-2: inorganic silicate, KS49, purchased from Xipusen New Materials Co., Ltd.;

[0049] Elastic Emulsion - 1: Acrylic emulsion, WT - 300S, purchased from Badfu;

[0050] Elastic Emulsion - 2: Styrene - acrylic emulsion, XG - 2101, purchased from Hengshui Xinguang New Materials Technology Co., Ltd.

[0051] Anti - settling Agent A: Associative acrylic acid, purchased from Münzing Chemie GmbH, Germany;

[0052] Dispersant: Acrylic polymer dispersant, purchased from Münzing Chemie GmbH, Germany;

[0053] Defoamer: Organosilicon defoamer, TEGO 904W, purchased from Evonik Industries;

[0054] Leveling Agent: Organosilicon - based wetting agent, TEGO 4100, purchased from Evonik Industries;

[0055] Zinc powder:

[0056] Flake zinc powder: 1000 mesh, purchased from Hunan Xinweiling;

[0057] Spherical zinc powder: 1000 mesh, purchased from Hunan Xinweiling;

[0058] Hydrotalcite - 1: WP, purchased from Zhejiang Fenghong New Materials Co., Ltd.;

[0059] Hydrotalcite - 2: AC - 027, purchased from Chenghe Technology Co., Ltd.;

[0060] Talc powder: 800 mesh, commercially available;

[0061] Rust - preventive pigment: Modified zinc phosphate, commercially available;

[0062] Silane coupling agent: 6040, purchased from Dow Corning;

[0063] Anti - settling Agent B: 972, purchased from Evonik Industries;

[0064] Propylene glycol methyl ether: commercially available;

[0065] Absolute ethanol: commercially available.

[0066] Examples 1 - 9

[0067] The present invention provides a series of water - borne primers, and the preparation method includes the following steps:

[0068] Preparing Component A:

[0069] S1. Premixing: Mix the elastic emulsion, dispersant and water evenly to obtain a premix;

[0070] S2. Add anti-settling agent A to the premix obtained in step S1, mix evenly, then continue to add waterborne inorganic resin, dispersant, defoamer, and leveling agent and mix evenly to obtain Component A;

[0071] Prepare Component B:

[0072] S1. Premixing: Mix alcohol ether-based polar organic compound, silane coupling agent, and absolute ethanol evenly to obtain a premix;

[0073] S2. Add anti-settling agent B to the premix obtained in step S1, mix evenly, then sequentially add hydrotalcite, zinc powder, and rust-inhibiting pigment and mix evenly to obtain Component B.

[0074] Table 1 Raw material formula (parts by weight) of the waterborne primer in Examples 1 to 6

[0075]

[0076]

[0077] Comparative Example 1

[0078] This comparative example provides a waterborne primer, which is prepared according to the method of Example 4. The difference from Example 4 is that hydrotalcite-1 in Component B is replaced with talcum powder of equal mass.

[0079] Comparative Example 2

[0080] This comparative example provides a waterborne primer, which is prepared according to the method of Example 4. The difference from Example 4 is that hydrotalcite-1 in Component B is replaced with spherical zinc powder of equal mass, that is, in this comparative example, hydrotalcite is not added.

[0081] Comparative Example 3

[0082] This comparative example provides a waterborne primer, which is prepared according to the method of Example 4. The difference from Example 4 is that silane coupling agent is not added in Component B.

[0083] Comparative Example 4

[0084] This comparative example provides a waterborne primer, which is prepared according to the method of Example 4. The difference from Example 4 is that propylene glycol monomethyl ether is not added in Component B.

[0085] Comparative Example 5

[0086] This comparative example provides a waterborne primer, which is prepared according to the method of Example 4. The difference from Example 4 is that elastic emulsion-1 in Component A is replaced with an equal amount of waterborne inorganic resin-1.

[0087] Comparative Example 6

[0088] This comparative example provides an aqueous primer, which is prepared according to the raw material composition of Example 4 by a preparation method including the following steps: The preparation of Component A is the same as that of Example 4. For Component B, all raw materials are added simultaneously and mixed evenly.

[0089] Comparative Example 7

[0090] This comparative example provides an aqueous primer, which is prepared according to the method of Example 4. The difference from Example 4 is that in Component B, spherical zinc powder is replaced with flaky zinc powder in equal amounts.

[0091] Comparative Example 8

[0092] This comparative example provides an aqueous primer, which is prepared according to the method of Example 4. The difference from Example 4 is that in Component B, flaky zinc powder is replaced with spherical zinc powder in equal amounts.

[0093] Performance Test

[0094] After the Component A and Component B of the aqueous primers obtained in the above examples and comparative examples are mixed evenly according to a weight ratio of 1:1, they are diluted with water to an appropriate viscosity as needed to obtain an aqueous primer coating. Then, it is sprayed on the surface of a steel plate (the surface is sandblasted) used on-site for ships by high-pressure airless spraying to obtain a dry film with a thickness of 20 ± 0.5 μm.

[0095] 1. The surface drying time (min), adhesion (grade, where the higher the grade number, the worse the adhesion), weather resistance, welding and cutting performance are tested according to the method in GB / T 6747-2008 "Shop Primer for Ships". The test results are shown in Table 2;

[0096] 2. Compatibility performance: After obtaining the dry film, after 24 hours, an aqueous epoxy zinc-rich primer with a content of 80% (aqueous paint JT-268D purchased from Guangzhou Jitai Chemical Co., Ltd.) is sprayed. The dry film thickness is 90 ± 2 μm. Observe the appearance of the paint film after spraying the primer: If there are no blisters, pinholes, etc. on the appearance, it is recorded as "normal"; and the adhesion of the paint film (MPa) is tested by the pull-off method. The test method for the pull-off adhesion is tested according to GB / T 5120-2006. The test results are shown in Table 2;

[0097] 3. Construction performance evaluation: During the spraying process of the primer, if it is smooth and there are no adverse phenomena such as sagging and gun clogging, it is recorded as "qualified", otherwise it is recorded as unqualified. The test results are shown in Table 2.

[0098] Table 2 Test Results of the Aqueous Primers Obtained in the Examples and Comparative Examples

[0099]

[0100]

[0101] It can be seen from the above results that:

[0102] After the water-based primer of the present invention forms a film, it has excellent sprayable construction performance and matching performance, and the comprehensive performance of the paint film is excellent. Among them: the surface drying time is within 5 minutes, and can be as low as 3 minutes; the weather resistance is more than 9 months, and can be as high as 15 months; the adhesion to the substrate is good, and all can reach level 1.

[0103] The results of Examples 1 to 9 show that when the raw materials are within the above dosage ranges, the prepared water-based primer has excellent comprehensive performance after film formation.

[0104] The results of the comparative examples further show that the combined action of zinc powder, hydrotalcite, polar organic compounds of alcohol ethers, and elastic emulsion improves the performance of the paint film, and only by adopting a specific preparation process can the raw materials in the system fully interact with each other to form a specific structure, improving the sprayability and weather resistance of the primer.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An aqueous primer, characterized in that, It comprises components in the following parts by weight: Component A, with a total weight of 50 parts: Component B, with a total weight of 50 parts: The zinc powder includes spherical zinc powder and flaky zinc powder; Among them, the preparation method of Component B includes the following steps: S1. Premixing: Mix an alcohol ether-based polar organic compound, a silane coupling agent, and absolute ethanol evenly to obtain a premix; S2. After adding anti-settling agent B to the premix obtained in step S1 and mixing evenly, successively add hydrotalcite, zinc powder, and rust-inhibiting pigment and mix evenly to obtain Component B.

2. The water-based primer according to claim 1, wherein The alcohol ether-based polar organic compound includes one or a combination of propylene glycol methyl ether, dipropylene glycol methyl ether, or ethylene glycol propyl ether.

3. The water-based primer according to claim 1, characterized in that, The zinc powder includes spherical zinc powder and flaky zinc powder, and the weight ratio of the spherical zinc powder to the flaky zinc powder is spherical zinc powder: flaky zinc powder = (1 - 6):

1.

4. The water-based primer according to claim 1, wherein The rust-inhibiting pigment includes one or a combination of zinc phosphate, micaceous iron oxide, aluminum tripolyphosphate, lithium silicate, and phosphorous iron powder.

5. The water-based primer according to claim 1, characterized in that, The particle size of the hydrotalcite < 30 μm.

6. The water-based primer according to claim 1, wherein, The waterborne inorganic resin includes one or a combination of potassium silicate, lithium silicate, sodium silicate, or silica sol.

7. The water-based primer according to claim 1, characterized in that, The elastic emulsion includes acrylic emulsion.

8. The water-based primer according to claim 1, characterized in that, Meet at least one of the following conditions: 1) The anti-settling agent A includes one or a combination of polyurethane, associative acrylic acid, and polyamide wax; 2) The anti-settling agent B includes one or a combination of nano-montmorillonite, organic bentonite, and fumed silica; 3) The dispersant includes one or a combination of polyether compounds, acrylic polymers, and phosphate ester compounds; 4) The defoaming agent includes one or a combination of silicone defoaming agents, polyether defoaming agents, and mineral oil defoaming agents; 5) The leveling agent includes one or a combination of silicone leveling agents and fluorine-containing leveling agents; 6) The silane coupling agent includes one or a combination of amino silanes and epoxy silanes.

9. The preparation method of the aqueous primer according to any one of claims 1 to 8, characterized in that, It includes the following steps: Preparation of Component A: S1. Premixing: Mix the elastic emulsion, dispersant, and water evenly to obtain a premix; S2. After adding anti-settling agent A to the premix obtained in step S1 and mixing evenly, continue to add the waterborne inorganic resin, dispersant, defoaming agent, and leveling agent and mix evenly to obtain Component A; Preparation of Component B: S1. Premixing: Mix the alcohol ether-based polar organic compound, silane coupling agent, and absolute ethanol evenly to obtain a premix; S2. After adding anti-settling agent B to the premix obtained in step S1 and mixing evenly, successively add hydrotalcite, zinc powder, and rust-inhibiting pigment and mix evenly to obtain Component B.

10. Application of the waterborne primer according to any one of claims 1 - 8 in manufacturing ships, bridges, or mechanical equipment.

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