A water-based anti-corrosion topcoat and its preparation method and application, oil casing

Abstract

The present invention discloses a water-based anti-corrosion topcoat, a preparation method and application thereof, and an oil casing, relating to the technical field of oil casing anti-corrosion. The preparation method comprises the following steps: stirring 13.5 to 58.7 parts by mass of water, 0.1 to 0.5 parts of a wetting and dispersing agent, and 0.1 to 0.5 parts of a defoaming agent at 300 to 500 rpm; adding 10 to 20 parts of an anti-rust pigment and dispersing the mixture at 1200 to 1500 rpm to a fineness of ≤25 μm; adding 15 to 20 parts of a water-based acrylic resin and 10 to 30 parts of a water-based aspartame polyurea resin and stirring the mixture at 790 to 810 rpm for 9 to 10 minutes; adding 0.1 to 0.5 parts of an adhesion promoter, 5 to 10 parts of a film-forming aid, and 1 to 5 parts of a thickener, stirring the mixture at 36 to 40°C, and adjusting the viscosity to 80 to 100 KU. The paint film formed by the prepared water-based anti-corrosion topcoat has a salt spray resistance of ≥1000h and an adhesion of level 0.

Description

Technical Field

[0001] The present invention relates to the technical field of oil casing anti-corrosion, and in particular to a water-based anti-corrosion topcoat, a preparation method and application thereof, and an oil casing. Background Art

[0002] Since some oil and gas fields are highly corrosive, it is necessary to coat the surface of the oil casing with protective paint to meet the long-term anti-corrosion requirements in the highly corrosive oil and gas field environment.

[0003] However, conventional solvent-based anti-corrosion topcoats contain high levels of VOCs (volatile organic compounds), making them environmentally unsuitable. Conventional water-based topcoats (such as pure acrylic and epoxy systems) exhibit poor corrosion resistance (salt spray resistance ≤ 500 hours) and insufficient adhesion (cross-hatch adhesion ≥ Grade 1), making them inadequate for the long-term protection of oil casing and tubing in high-temperature, high-salt spray environments. Furthermore, their process adaptability is poor, resulting in long curing and drying times during coating, and the tendency for sags and pinholes to form on the tubing surface.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] Based on the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a water-based anti-corrosion topcoat and its preparation method and application, and oil casing, aiming to solve the problem of poor corrosion resistance of existing water-based topcoats.

[0006] The technical solutions of the present invention are as follows:

[0007] A first aspect of the present invention provides a method for preparing a water-based anti-corrosion topcoat, wherein the water-based anti-corrosion topcoat comprises the following components in parts by weight:

[0008] 15-20 parts of water-based acrylic resin, 10-30 parts of water-based aspartame polyurea resin, 10-20 parts of anti-rust pigment, 0.1-0.5 parts of wetting and dispersing agent, 0.1-0.5 parts of defoaming agent, 0.1-0.5 parts of adhesion promoter, 5-10 parts of film-forming aid, 1-5 parts of thickener and 13.5-58.7 parts of water;

[0009] The anti-rust pigment is composed of zinc phosphate and aluminum tripolyphosphate in a mass ratio of (2.5-3.5):1;

[0010] The preparation method of the water-based anti-corrosion topcoat comprises the following steps:

[0011] According to the mass parts of the water-based anti-corrosion topcoat components, water, a wetting dispersant and a defoamer are stirred at a speed of 300-500 rpm for 3-5 minutes; then, an anti-rust pigment is added and dispersed at a speed of 1200-1500 rpm until the system fineness is ≤25 μm; then, a water-based acrylic resin and a water-based aspartame polyurea resin are added and stirred at a speed of 790-810 rpm for 9-10 minutes; finally, an adhesion promoter, a film-forming aid and a thickener are added, and the mixture is stirred at a temperature of 36-40° C. to adjust the viscosity to 80-100 KU to obtain the water-based anti-corrosion topcoat.

[0012] Optionally, the water-based anti-corrosion topcoat comprises the following components in parts by mass:

[0013] 18-20 parts of water-based acrylic resin, 15-25 parts of water-based aspartame polyurea resin, 12-18 parts of anti-rust pigment, 0.2-0.3 parts of wetting and dispersing agent, 0.2-0.3 parts of defoaming agent, 0.2-0.4 parts of adhesion promoter, 6-8 parts of film-forming aid, 2-3 parts of thickener and 25-46.4 parts of water.

[0014] Optionally, the mass ratio of the water-based acrylic resin to the water-based aspartame polyurea resin is 1:(1.1~1.5).

[0015] Optionally, the adhesion promoter is a silane coupling agent.

[0016] Optionally, the film-forming aid includes at least one of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and dipropylene glycol butyl ether.

[0017] Optionally, the particle size D50 of the anti-rust pigment is ≤5 μm.

[0018] A second aspect of the present invention provides a water-based anti-corrosion topcoat, wherein the water-based anti-corrosion topcoat is prepared by the preparation method of the present invention as described above.

[0019] A third aspect of the present invention provides a use of the water-based anti-corrosion topcoat of the present invention in the field of surface protection of oil casing pipes.

[0020] Optionally, the application method includes the following steps:

[0021] The water-based anti-corrosion topcoat is applied on the surface of the oil casing pipe body.

[0022] A fourth aspect of the present invention provides an oil casing, wherein the oil casing is prepared by the following preparation steps:

[0023] Provide oil casing and tubing body;

[0024] The water-based anti-corrosion topcoat of the present invention is applied to the surface of the oil casing body and then dried.

[0025] Beneficial Effects: By utilizing a dual-resin synergistic cross-linking system, a composite anti-rust system, and suitable additives, along with a specific preparation process, the present invention produces a water-based anti-corrosion topcoat with a low VOC content, suitable viscosity, and good storage stability. The paint film formed by this water-based anti-corrosion topcoat exhibits excellent corrosion resistance (salt spray resistance ≥ 1000 hours), grade 0 adhesion, a smooth, defect-free surface, and excellent flexibility and impact resistance. The water-based anti-corrosion topcoat prepared using the preparation method provided herein is used for long-term protection of oil casing and tubing in high-temperature, high-salt spray environments, combining environmental friendliness with construction adaptability. DETAILED DESCRIPTION

[0026] The present invention provides a water-based anti-corrosion topcoat, a preparation method and application thereof, and an oil casing. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0027] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] An embodiment of the present invention provides a method for preparing a water-based anti-corrosion topcoat (which is a water-based heavy-duty anti-corrosion topcoat), wherein the water-based anti-corrosion topcoat comprises the following components in parts by weight:

[0029] 15-20 parts of water-based acrylic resin, 10-30 parts of water-based aspartame polyurea resin, 10-20 parts of anti-rust pigment, 0.1-0.5 parts of wetting and dispersing agent, 0.1-0.5 parts of defoaming agent, 0.1-0.5 parts of adhesion promoter, 5-10 parts of film-forming aid, 1-5 parts of thickener and 13.5-58.7 parts of water;

[0030] The anti-rust pigment is composed of zinc phosphate and aluminum tripolyphosphate in a mass ratio of (2.5-3.5):1 (for example, the mass ratio of zinc phosphate to aluminum tripolyphosphate is 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1 or 3.5:1, etc.);

[0031] The preparation method of the water-based anti-corrosion topcoat comprises the following steps:

[0032] According to the weight parts of the water-based anti-corrosion topcoat components, water, a wetting and dispersing agent, and a defoaming agent are stirred at a speed of 300 to 500 rpm (for example, 300 rpm, 350 rpm, 400 rpm, 450 rpm, or 500 rpm, etc.) for 3 to 5 minutes (for example, 3 minutes, 4 minutes, or 5 minutes, etc.);

[0033] Then add the anti-rust pigment and disperse it at a speed of 1200-1500 rpm (for example, 1200 rpm, 1300 rpm, 1400 rpm or 1500 rpm, etc.) until the system fineness is ≤25 μm;

[0034] Then, add water-based acrylic resin and water-based aspartame polyurea resin, and stir at a speed of 790-810 rpm (for example, 790 rpm, 800 rpm, or 810 rpm, etc.) for 9-10 minutes (for example, 9 minutes, 9.5 minutes, or 10 minutes, etc.);

[0035] Finally, an adhesion promoter, a film-forming aid, and a thickener are added, and the mixture is stirred at a temperature of 36 to 40° C. (i.e., the temperature of the system during stirring is controlled to be 36 to 40° C., for example, 36° C., 37° C., 38° C., 39° C., or 40° C.), and the viscosity is adjusted to 80 to 100 KU (for example, 80 KU, 85 KU, 90 KU, 95 KU, or 100 KU), to obtain the water-based anti-corrosion topcoat.

[0036] Through research, the inventors discovered that not only the formulation but also the preparation process significantly influences the performance of water-based anticorrosive topcoats. Therefore, by utilizing a dual-resin synergistic cross-linking system, a composite antirust system (zinc phosphate and aluminum tripolyphosphate in a specific mass ratio), and suitable additives, along with a specific preparation process, the present invention achieves a water-based anticorrosive topcoat with a low VOC content, a suitable viscosity (80-100 kU), and good storage stability. The resulting film exhibits excellent salt spray resistance (≥1000 hours), grade 0 adhesion, a smooth, defect-free surface, and excellent flexibility and impact resistance. The water-based anticorrosive topcoat prepared using the present method is used for long-term protection of oil casing and tubing in high-temperature, high-salt spray environments, combining environmental friendliness with construction suitability.

[0037] The effects and dosages of the components in this embodiment are as follows:

[0038] A water-based acrylic resin content of 15-20 parts by weight can impart good adhesion, weather resistance, gloss, and flexibility to the paint film. Using too much of this resin improves the film's flexibility, gloss, and weather resistance, but reduces its hardness and abrasion resistance. Using too little of this resin can reduce adhesion and flexibility.

[0039] A water-based aspartame polyurea resin dosage of 10 to 30 parts by weight can significantly improve the paint film's wear resistance, weather resistance, impact resistance, and rapid curing properties, making it particularly suitable for applications requiring high levels of protective performance. While using too high a dosage can enhance the paint film's physical properties and chemical resistance, it can also increase costs and affect its compatibility with other ingredients. Using too low a dosage can weaken the paint film's wear and weather resistance.

[0040] Anti-rust pigment (composed of zinc phosphate and aluminum tripolyphosphate in a 3:1 mass ratio) is used in an amount of 10-20 parts by weight to prevent rust and corrosion on metal substrates. This prevents oxygen, moisture, and other corrosive substances from contacting the metal substrate through physical shielding or chemical passivation. While excessive dosage may enhance the anti-rust effect, it may also affect the leveling and gloss of the paint film. Excessive dosage may result in insufficient anti-rust performance.

[0041] In addition, water-based acrylic resin, water-based asparagus polyurea resin and rust-proof pigment have synergistic effect, water-based acrylic resin and water-based asparagus polyurea resin are film-forming substances, and both are coordinated and cross-linked to form a continuous and dense paint film, and water-based acrylic resin has good adhesion, weather resistance, flexibility and glossiness after film formation, and water-based asparagus polyurea resin gives the paint film excellent wear resistance, weather resistance, impact resistance and fast curing performance, and is particularly suitable for scenes with higher requirements on protective performance. The two cooperate with each other so that the paint film has both advantages, improves the comprehensive performance of the paint film. In addition, if the two ratios are improperly matched, there will be phase separation phenomenon, resulting in defects on the paint film surface, such as uneven gloss, cracking, etc., affecting the appearance and performance of the paint film. And the ratio adopted in the present embodiment can avoid the above problems from occurring. The water-based acrylic resin, water-based aspartame polyurea resin and anti-rust pigment are used in combination with the preparation method provided in this embodiment, so that the water-based acrylic resin and water-based aspartame polyurea resin can wrap the anti-rust pigment, fix the anti-rust pigment in the paint film, and ensure that the anti-rust pigment is evenly distributed in the paint film, exerting its anti-rust effect and preventing the anti-rust pigment from settling during storage.

[0042] The wetting and dispersing agent, used in an amount of 0.1 to 0.5 parts by weight, can reduce the surface tension of the waterborne acrylic resin, waterborne aspartame polyurea resin, and anti-rust pigment, making them more easily wetted and dispersed by water, thus evenly dispersing them in the waterborne anti-corrosion topcoat and preventing agglomeration and precipitation. Furthermore, a good dispersion helps the film-forming substances, the waterborne acrylic resin and waterborne aspartame polyurea resin, evenly coat the anti-rust pigment, improving the stability and uniformity of the waterborne anti-corrosion topcoat, enhancing the anti-rust effect and the physical properties of the paint film. If the dosage is too high, the water resistance and drying speed of the paint film will be affected; if the dosage is too low, the anti-rust pigment will be unevenly dispersed.

[0043] The weight percentage of adhesion promoter is 0.1-0.5 parts. It can enhance the adhesion between the paint film and the metal substrate, ensuring that the paint film is firmly attached to the metal substrate and improving the durability of the paint film. If the dosage is too high, the stability and drying speed of the water-based anti-corrosion topcoat will be affected; if the dosage is too low, the paint film will have insufficient adhesion.

[0044] The film-forming aid, used in an amount of 5 to 10 parts by weight, can lower the glass transition temperature of the film-forming substance, lowering the minimum film-forming temperature of the water-based anticorrosive topcoat, helping the water-based anticorrosive topcoat form a continuous, uniform paint film at a lower temperature. The film-forming aid also improves the fluidity and flexibility of the film-forming substance, enhancing the performance and appearance of the paint film. Using too much of the film-forming aid increases costs and VOC emissions; using too little of the film-forming aid can lead to poor film formation, cracking, and powdering.

[0045] A thickener dosage of 1-5 parts by weight ensures the water-based anti-corrosion topcoat has an appropriate viscosity, preventing settling and sagging during storage and application, and ensuring good application performance (flowability and leveling). The appropriate viscosity also helps maintain uniform distribution of the anti-rust pigment during application, improving the quality of the paint film. Using too much thickener will result in excessive viscosity, affecting leveling and causing surface defects such as orange peel. Using too little thickener can lead to sagging.

[0046] The mass proportion of water is 13.5 to 58.7 parts. As a solvent, water is an environmentally friendly solvent, which reduces VOC emissions and enables the water-based anti-corrosion topcoat to have good construction performance.

[0047] In some embodiments, the water is deionized water.

[0048] In some embodiments, the water-based anti-corrosion topcoat comprises the following components in parts by mass:

[0049] 18-20 parts of water-based acrylic resin, 15-25 parts of water-based aspartame polyurea resin, 12-18 parts of anti-rust pigment, 0.2-0.3 parts of wetting and dispersing agent, 0.2-0.3 parts of defoaming agent, 0.2-0.4 parts of adhesion promoter, 6-8 parts of film-forming aid, 2-3 parts of thickener and 25-46.4 parts of water.

[0050] In some embodiments, the mass ratio of the waterborne acrylic resin to the waterborne aspart polyurea resin is 1:(1.1-1.5). This ratio can result in a faster drying time for the waterborne anticorrosive topcoat, stronger adhesion between the paint film formed by the waterborne anticorrosive topcoat and the metal substrate, and a higher crosslinking density between the waterborne acrylic resin and the waterborne aspart polyurea resin, thereby forming a denser paint film and further improving corrosion resistance.

[0051] In some embodiments, the adhesion promoter is a silane coupling agent.

[0052] In some embodiments, the film-forming aid includes at least one of, but is not limited to, 2,2,4-trimethylpentanediol monoisobutyrate (also known as alcohol ester dodecahydrate) and dipropylene glycol butyl ether. Compared to dipropylene glycol butyl ether, when 2,2,4-trimethylpentanediol monoisobutyrate is used as the film-forming aid, the VOC content of the water-based anti-corrosion topcoat is lower, and can be less than or equal to 50 g / L.

[0053] In some embodiments, the anti-rust pigment has a particle size D50 (i.e., the critical particle size at 50% of the cumulative particle size distribution) of 5 μm or less. This particle size facilitates dispersion to a fineness of 25 μm or less at a rotation speed of 1200-1500 rpm. The particle size of the anti-rust pigment can affect the film-forming process and film performance of the film-forming substance. If the particle size of the anti-rust pigment is too large, it may lead to excessive fineness and uneven dispersion, thereby disrupting the continuity of the paint film and reducing the corrosion resistance and water resistance of the paint film.

[0054] In some embodiments, after adjusting the viscosity to 80-100 KU, the process further includes the steps of aging and filtering.

[0055] In some embodiments, the aging time is 20 to 30 hours, for example, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours or 30 hours.

[0056] An embodiment of the present invention further provides a water-based anti-corrosion topcoat, wherein the water-based anti-corrosion topcoat comprises the following components in parts by mass:

[0057] 15-20 parts of water-based acrylic resin, 10-30 parts of water-based aspartame polyurea resin, 10-20 parts of anti-rust pigment, 0.1-0.5 parts of wetting and dispersing agent, 0.1-0.5 parts of defoaming agent, 0.1-0.5 parts of adhesion promoter, 5-10 parts of film-forming aid, 1-5 parts of thickener and 13.5-58.7 parts of water;

[0058] The anti-rust pigment is composed of zinc phosphate and aluminum tripolyphosphate in a mass ratio of (2.5-3.5):1;

[0059] The water-based anti-corrosion topcoat is prepared by the following preparation steps:

[0060] According to the mass parts of the above-mentioned water-based anti-corrosion topcoat components, water, a wetting dispersant and a defoamer are stirred at a speed of 300-500 rpm for 3-5 minutes; then, an anti-rust pigment is added and dispersed at a speed of 1200-1500 rpm until the system fineness is ≤25 μm; then, a water-based acrylic resin and a water-based aspartame polyurea resin are added and stirred at a speed of 790-810 rpm for 9-10 minutes; finally, an adhesion promoter, a film-forming aid and a thickener are added, and the mixture is stirred at a temperature of 36-40° C. to adjust the viscosity to 80-100 KU to obtain the water-based anti-corrosion topcoat.

[0061] The water-based anti-corrosion topcoat provided in the embodiments of the present invention has a low VOC content, a suitable viscosity (80-100 kU), and good storage stability. The paint film formed by this water-based anti-corrosion topcoat exhibits excellent corrosion resistance (salt spray resistance ≥ 1000 hours), grade 0 adhesion, a smooth, defect-free surface, and excellent flexibility and impact resistance. The water-based anti-corrosion topcoat provided in the embodiments of the present invention is used for long-term protection of oil casing and tubing in high-temperature, high-salt spray environments, achieving both environmental friendliness and construction suitability.

[0062] The embodiment of the present invention further provides an application of the water-based anti-corrosion topcoat described above in the field of surface protection of oil casing pipes.

[0063] In some embodiments, the method of application comprises the following steps:

[0064] The water-based anti-corrosion topcoat is applied on the surface of the oil casing pipe body.

[0065] An embodiment of the present invention further provides an oil casing, wherein the oil casing is prepared by the following preparation steps:

[0066] Provide oil casing and tubing body;

[0067] The water-based anti-corrosion topcoat described above in the embodiment of the present invention is applied to the surface of the oil casing body and then dried.

[0068] In this embodiment, the water-based anti-corrosion topcoat on the surface of the oil casing body forms a paint film after drying. That is, the oil casing includes the oil casing body and the paint film on the surface of the oil casing body.

[0069] The present invention will be further described below with reference to specific examples.

[0070] Example 1

[0071] This embodiment provides a water-based anti-corrosion topcoat and a preparation method thereof. The water-based anti-corrosion topcoat comprises the following components in parts by weight:

[0072] 18 parts of water-based acrylic resin, 22 parts of water-based aspartame polyurea resin, 15 parts of rust-proof pigment, 0.3 parts of wetting and dispersing agent, 0.2 parts of defoaming agent, 0.3 parts of adhesion promoter, 7 parts of film-forming aid, 2.5 parts of thickener and 34.7 parts of deionized water;

[0073] Among them, water-based acrylic resin was purchased from Guangdong Keding Functional Materials Co., Ltd., model MR1830W;

[0074] Water-based asparagus polyurea resin was purchased from Nanjing Weixin Polymer Technology Co., Ltd., model LF-AP50;

[0075] The anti-rust pigment is composed of zinc phosphate and aluminum tripolyphosphate in a mass ratio of 3:1, and the particle size D50 of the anti-rust pigment is 4 μm;

[0076] The wetting and dispersing agent was purchased from Altana AG, Germany, model BYK-190;

[0077] The defoamer was purchased from Altana AG, Germany, model BYK-024;

[0078] Adhesion promoter was purchased from Shandong Pinshang New Materials Co., Ltd., specifically silane coupling agent KH-550;

[0079] The film-forming aid was 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, purchased from Eastman Chemicals (Nanjing) Co., Ltd. under the brand name Texanol;

[0080] The thickener was Rohm and Haas ACRYSOL RM-8W nonionic polyurethane rheology modifier, purchased from The Dow Chemical Company.

[0081] The preparation method of the water-based anti-corrosion topcoat comprises the following steps:

[0082] Deionized water, a wetting and dispersing agent, and a defoaming agent were placed in a disperser (purchased from Hangzhou Qiwei Instrument Co., Ltd., model GFJ-0.7) according to the mass parts of the above components, and stirred at 400 rpm for 4 min until they were evenly mixed (without stratification).

[0083] Add anti-rust pigment and stir and disperse at a speed of 1300 rpm until the system fineness reaches 21 μm;

[0084] Add water-based acrylic resin and water-based aspartame polyurea resin in sequence and stir at 800 rpm for 10 min;

[0085] An adhesion promoter, a film-forming aid and a thickener were added, the mixture was stirred at a temperature of 36° C., the viscosity was adjusted to 89 KU, and the mixture was aged for 24 hours and then filtered to obtain the water-based anti-corrosion topcoat.

[0086] Example 2

[0087] This embodiment provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0088] 15 parts of water-based acrylic resin, 30 parts of water-based aspartame polyurea resin, and 29.7 parts of deionized water;

[0089] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0090] Example 3

[0091] This embodiment provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0092] 20 parts of water-based acrylic resin, 10 parts of water-based aspartame polyurea resin, 44.7 parts of deionized water;

[0093] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0094] Example 4

[0095] This embodiment provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0096] 20 parts of water-based acrylic resin, 25 parts of water-based aspartame polyurea resin, and 29.7 parts of deionized water;

[0097] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0098] Example 5

[0099] This embodiment provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0100] 18 parts of water-based acrylic resin, 15 parts of water-based aspartame polyurea resin, 41.8 parts of deionized water;

[0101] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0102] Example 6

[0103] This embodiment provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0104] The film-forming aid is dipropylene glycol butyl ether (DPnB);

[0105] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0106] Comparative Example 1

[0107] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0108] 40 parts of water-based acrylic resin, 0 parts of water-based aspartame polyurea resin;

[0109] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0110] Comparative Example 2

[0111] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0112] 0 parts of water-based acrylic resin, 40 parts of water-based aspartame polyurea resin;

[0113] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0114] Comparative Example 3

[0115] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0116] 12 parts of water-based acrylic resin, 28 parts of water-based aspartame polyurea resin;

[0117] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0118] Comparative Example 4

[0119] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0120] 18 parts of water-based acrylic resin, 22 parts of water-based epoxy resin;

[0121] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0122] Comparative Example 5

[0123] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0124] The anti-rust pigment is a composite zinc-aluminum powder (mixed from zinc powder and aluminum powder), where the mass ratio of zinc powder to aluminum powder is 1:4.5;

[0125] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0126] Comparative Example 6

[0127] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which differs from Example 1 only in that:

[0128] The anti-rust pigment is composed of zinc phosphate and aluminum tripolyphosphate in a mass ratio of 2:1;

[0129] The remaining components, their weight parts, and preparation method are the same as those in Example 1.

[0130] Comparative Example 7

[0131] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which has the same formula as the water-based anti-corrosion topcoat in Example 1, and differs only in the preparation method. The preparation method of the water-based anti-corrosion topcoat in this comparative example comprises the following steps:

[0132] Deionized water, a wetting and dispersing agent, and a defoaming agent were placed in a disperser (purchased from the same manufacturer and model as in Example 1) and stirred at 260 rpm (the mixture could not be mixed uniformly at this speed) for 4 minutes;

[0133] Add anti-rust pigment and stir and disperse at a speed of 1300 rpm until the system fineness reaches 24 μm;

[0134] Add water-based acrylic resin and water-based aspartame polyurea resin in sequence and stir at 800 rpm for 10 min;

[0135] An adhesion promoter, a film-forming aid and a thickener were added, the mixture was stirred at a temperature of 36° C., the viscosity was adjusted to 81 KU, and the mixture was aged for 24 hours and then filtered to obtain the water-based anti-corrosion topcoat.

[0136] Comparative Example 8

[0137] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which has the same formula as the water-based anti-corrosion topcoat in Example 1, and differs only in the preparation method. The preparation method of the water-based anti-corrosion topcoat in this comparative example comprises the following steps:

[0138] Deionized water, wetting dispersant and defoaming agent were placed in a disperser (purchased from the same manufacturer and model as in Example 1) and stirred at 500 rpm for 3 minutes to mix evenly;

[0139] Add anti-rust pigment and stir at 1000 rpm to disperse the system to a fineness of 26 μm;

[0140] Add water-based acrylic resin and water-based aspartame polyurea resin in sequence and stir at 800 rpm for 10 min;

[0141] An adhesion promoter, a film-forming aid and a thickener were added, the mixture was stirred at a temperature of 36° C., the viscosity was adjusted to 85 KU, and the mixture was aged for 24 hours and then filtered to obtain the water-based anti-corrosion topcoat.

[0142] Comparative Example 9

[0143] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which has the same formula as the water-based anti-corrosion topcoat in Example 1, and differs only in the preparation method. The preparation method of the water-based anti-corrosion topcoat in this comparative example comprises the following steps:

[0144] Deionized water, wetting dispersant and defoaming agent were placed in a disperser (purchased from the same manufacturer and model as in Example 1) and stirred at 300 rpm for 4 minutes to mix evenly;

[0145] Add anti-rust pigment and stir and disperse at a speed of 1500 rpm until the system fineness reaches 21 μm;

[0146] Add water-based acrylic resin and water-based aspartame polyurea resin in sequence and stir at 1000 rpm for 10 min;

[0147] An adhesion promoter, a film-forming aid and a thickener were added, the mixture was stirred at a temperature of 38° C., the viscosity was adjusted to 100 KU, and the mixture was aged for 24 hours and then filtered to obtain the water-based anti-corrosion topcoat.

[0148] Comparative Example 10

[0149] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof, which has the same formula as the water-based anti-corrosion topcoat in Example 1, and differs only in the preparation method. The preparation method of the water-based anti-corrosion topcoat in this comparative example comprises the following steps:

[0150] Deionized water, wetting dispersant and defoaming agent were mixed in a disperser (purchased from the same manufacturer and model as in Example 1) at 500 rpm for 3 minutes until uniformly mixed;

[0151] Add anti-rust pigment and stir and disperse at a speed of 1200 rpm until the system fineness reaches 18 μm;

[0152] Add water-based acrylic resin and water-based aspartame polyurea resin in sequence and stir at 800 rpm for 10 min;

[0153] An adhesion promoter, a film-forming aid and a thickener were added, the mixture was stirred at a temperature of 46° C., the viscosity was adjusted to 80 KU, and the mixture was aged for 24 hours and then filtered to obtain the water-based anti-corrosion topcoat.

[0154] Comparative Example 11

[0155] This comparative example provides a water-based anti-corrosion topcoat and a preparation method thereof. The only difference from Example 1 is the different amount of thickener in the water-based anti-corrosion topcoat formula and the different preparation method. In this comparative example, the thickener is 2 parts. The preparation method of the water-based anti-corrosion topcoat comprises the following steps:

[0156] Deionized water, wetting dispersant and defoaming agent were mixed in a disperser (purchased from the same manufacturer and model as in Example 1) at 360 rpm for 4 minutes until uniformly mixed.

[0157] Add anti-rust pigment and stir and disperse at a speed of 1400 rpm until the system fineness reaches 25 μm;

[0158] Add water-based acrylic resin and water-based aspartame polyurea resin in sequence and stir at 800 rpm for 10 min;

[0159] An adhesion promoter, a film-forming aid and a thickener were added, the mixture was stirred at a temperature of 40° C., the viscosity was adjusted to 72 KU, and the mixture was aged for 24 hours and then filtered to obtain the water-based anti-corrosion topcoat.

[0160] The performance tests of the water-based anti-corrosion topcoats in the above examples and comparative examples were performed, and the results are shown in Tables 1, 2 and 3.

[0161] Among them, each test method is carried out according to the following standards:

[0162] Salt spray resistance test method: GB / T 1771-2007 "Paints and varnishes - Determination of resistance to neutral salt spray" and GB / T1776-2008 "Paints and varnishes - Rating method for aging of coatings";

[0163] Adhesion test method: GB / T 9286-2021 "Scratch test for paint and varnish films";

[0164] Impact resistance test method: GB / T 1732-2020 "Determination of impact resistance of paint films";

[0165] Drying time test method: GB / T 1728-2020 "Determination of drying time of paint films and putty films";

[0166] Flexibility test method: GB / T 6742-2007 "Paint film bending test (cylindrical shaft)";

[0167] VOC content test method: GB 30981-2020 "Limits of Hazardous Substances in Industrial Protective Coatings".

[0168] Table 1. Test results of water-based anticorrosive topcoat in Examples 1-6

[0169]

[0170] Among them, drying time is the surface drying time, impact resistance is expressed by the height of the falling hammer, and Ra is the roughness.

[0171] The results in Table 1 show that the water-based anti-corrosion topcoat prepared using the preparation method provided by the present invention has a short dry-to-dry time and excellent stability (no delamination after storage at 50°C for 7 days, with minimal viscosity change). The paint film formed using this water-based anti-corrosion topcoat has a smooth, defect-free surface, good flexibility, salt spray resistance of greater than or equal to 1000 hours, adhesion of Class 0, good impact resistance, and a low VOC content. A comparison of Examples 1 and 6 shows that when 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is used as the film-forming aid, the VOC content is even lower, reaching a VOC content of ≤50 g / L, further meeting environmental protection requirements.

[0172] Table 2. Test results of water-based anticorrosive topcoat in Example 1 and Comparative Examples 1-6

[0173]

[0174] Among them, drying time is the surface drying time, impact resistance is expressed by the height of the falling hammer, and Ra is the roughness.

[0175] In Table 2:

[0176] From the results of Example 1 and Comparative Examples 1 and 2, it can be seen that the water-based acrylic resin and the water-based aspartame polyurea resin in the present invention act synergistically, and the water-based anti-corrosion topcoat prepared by using water-based acrylic resin or water-based aspartame polyurea resin alone has poor salt spray resistance, adhesion, impact resistance and flexibility.

[0177] It can be seen from the results of Example 1 and Comparative Example 3 that the amount of water-based acrylic resin and water-based aspartame polyurea resin also has an important influence on the performance of the water-based anti-corrosion topcoat. When the amount of water-based acrylic resin and water-based aspartame polyurea resin in Example 1 is changed, the performance of the water-based anti-corrosion topcoat decreases.

[0178] It can be seen from the results of Example 1 and Comparative Example 4 that compared with the composite system of water-based acrylic resin and water-based epoxy resin, the water-based anti-corrosion topcoat based on water-based acrylic resin and water-based asparagus polyurea resin system provided by the present invention has better performance (good salt spray resistance, strong adhesion, good impact resistance, good storage stability, and short surface drying time).

[0179] It can be seen from the results of Example 1 and Comparative Example 5 that the selection of anti-rust pigment has a very large impact on the performance of water-based anti-corrosion topcoat, and the water-based anti-corrosion topcoat prepared with the anti-rust pigment selected in the present invention has better performance.

[0180] It can be seen from the results of Example 1 and Comparative Example 6 that the mass ratio of zinc phosphate to aluminum tripolyphosphate also has a very large influence on the performance of the water-based anti-corrosion topcoat. Changing the mass ratio of zinc phosphate to aluminum tripolyphosphate will reduce the salt spray resistance, adhesion strength and impact resistance of the paint film formed by the water-based anti-corrosion topcoat.

[0181] Table 3. Test results of water-based anticorrosive topcoat in Example 1 and Comparative Examples 7-11

[0182]

[0183] Among them, drying time is the surface drying time, impact resistance is expressed by the height of the falling hammer, and Ra is the roughness.

[0184] The results in Table 3 demonstrate that the preparation process significantly impacts the performance of waterborne anticorrosive topcoats. Only the waterborne anticorrosive topcoat prepared using the preparation method provided by the present invention exhibits excellent overall performance. However, changes in process parameters (such as rotation speed and temperature) can lead to varying degrees of degradation in salt spray resistance, adhesion, flexibility, and film appearance. Furthermore, the results of Example 1 and Comparative Example 10 demonstrate that increasing the stirring temperature also increases the VOC content. Furthermore, the results of Example 1 and Comparative Example 11 demonstrate that decreasing the viscosity increases the tack-free time of the waterborne anticorrosive topcoat, decreases storage stability, and deteriorates the film appearance.

[0185] It can be seen that in the present invention, by designing the components and proportions of the water-based anti-corrosion topcoat and adopting a specific preparation process, the water-based anti-corrosion topcoat ultimately has a low VOC content, suitable viscosity and good storage stability. The paint film formed by the water-based anti-corrosion topcoat has good corrosion resistance (salt spray resistance ≥ 1000 hours), adhesion of level 0, a smooth and defect-free surface, and good flexibility and impact resistance.

[0186] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a water-based anti-corrosion topcoat, characterized in that: The water-based anti-corrosion topcoat comprises the following components in parts by mass: 15-20 parts of water-based acrylic resin, 10-30 parts of water-based aspartame polyurea resin, 10-20 parts of anti-rust pigment, 0.1-0.5 parts of wetting and dispersing agent, 0.1-0.5 parts of defoaming agent, 0.1-0.5 parts of adhesion promoter, 5-10 parts of film-forming aid, 1-5 parts of thickener and 13.5-58.7 parts of water; The anti-rust pigment is composed of zinc phosphate and aluminum tripolyphosphate in a mass ratio of (2.5-3.5):1; The preparation method of the water-based anti-corrosion topcoat comprises the following steps: According to the mass parts of the water-based anti-corrosion topcoat components, water, a wetting dispersant and a defoamer are stirred at a speed of 300-500 rpm for 3-5 minutes; then, an anti-rust pigment is added and dispersed at a speed of 1200-1500 rpm until the system fineness is ≤25 μm; then, a water-based acrylic resin and a water-based aspartame polyurea resin are added and stirred at a speed of 790-810 rpm for 9-10 minutes; finally, an adhesion promoter, a film-forming aid and a thickener are added, and the mixture is stirred at a temperature of 36-40° C. to adjust the viscosity to 80-100 KU to obtain the water-based anti-corrosion topcoat.

2. The preparation method according to claim 1, characterized in that The water-based anti-corrosion topcoat comprises the following components in parts by mass: 18-20 parts of water-based acrylic resin, 15-25 parts of water-based aspartame polyurea resin, 12-18 parts of anti-rust pigment, 0.2-0.3 parts of wetting and dispersing agent, 0.2-0.3 parts of defoaming agent, 0.2-0.4 parts of adhesion promoter, 6-8 parts of film-forming aid, 2-3 parts of thickener and 25-46.4 parts of water.

3. The preparation method according to claim 1, characterized in that The mass ratio of the water-based acrylic resin to the water-based aspartame polyurea resin is 1:(1.1-1.5).

4. The preparation method according to claim 1, characterized in that The adhesion promoter is a silane coupling agent.

5. The preparation method according to claim 1, characterized in that The film-forming aid includes at least one of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and dipropylene glycol butyl ether.

6. The preparation method according to claim 1, characterized in that The particle size D50 of the anti-rust pigment is ≤5 μm.

7. A water-based anti-corrosion topcoat, characterized in that: The water-based anti-corrosion topcoat is prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the water-based anti-corrosion topcoat according to claim 7 in the field of surface protection of oil casing pipes.

9. The use according to claim 8, characterized in that The application method comprises the following steps: The water-based anti-corrosion topcoat is applied on the surface of the oil casing pipe body.

10. An oil casing, characterized in that: The oil casing is prepared by the following preparation steps: Provide oil casing and tubing body; The water-based anti-corrosion topcoat according to claim 7 is applied to the surface of the oil casing body and then dried.

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