A water-based anti-corrosion coating for air conditioners and its preparation process

Abstract

This invention relates to the field of coating technology and discloses a water-based anti-corrosion coating for air conditioning and its preparation process. The water-based anti-corrosion coating of this invention comprises 90-130 parts by weight of water, 100 parts by weight of water-based acrylic resin, and 0.5-2 parts by weight of cationic polyvinyl alcohol fiber, etc. The quaternary ammonium salt cationic groups of polyvinyl alcohol fiber and the carboxyl anionic groups in water-based acrylic resin form an electrostatic interaction. After curing into a paint film, polyvinyl alcohol and acrylic resin form a tight cross-linked network, which can inhibit the entry of corrosive media into the paint film, resulting in better anti-corrosion and salt spray resistance. Furthermore, the compatibility between the two is improved, the impact resistance and pencil hardness of the paint film are increased, and the mechanical properties are improved. It has good practical applications in air conditioning outdoor unit casings, heat exchanger fins, etc.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a water-based anti-corrosion coating for air conditioning and its preparation process. Background Technology

[0002] Metal components such as the outdoor unit casing, heat exchanger fins, and pipes of air conditioners are easily corroded by prolonged exposure to sunlight and rain, which can affect the performance of the air conditioner. These easily corroded metal parts usually require anti-corrosion coating treatment. Water-based acrylic resin is a resin material containing hydrophilic groups such as carboxyl groups, polymerized from monomers such as acrylic acid and acrylates. It has good water dispersibility, weather resistance, and flexibility, and has important applications in automobiles, air conditioning, wood products, and flooring. Current acrylic resin coatings have poor mechanical and anti-corrosion properties, requiring chemical modification, such as the addition of high-performance nanomaterials and fiber materials, to improve the overall performance of the coating.

[0003] Polyvinyl alcohol (PVA) fiber is inexpensive, readily available, has good tensile strength, and high mechanical strength, making it widely used in coatings, plastics, and concrete. Patent CN116285622B discloses a method for preparing fiber-reinforced coatings, using PVA fiber grafted with isocyanate and silicone-modified waterborne acrylic emulsion as raw materials. The resulting coating exhibits good hardness, water resistance, and flexibility. However, the PVA fiber in this patent does not improve the coating's corrosion resistance or other properties. Summary of the Invention

[0004] This invention solves the problems of poor corrosion resistance and strength of acrylic resin coatings.

[0005] The technical solution of the present invention is as follows: a water-based anti-corrosion coating, comprising 90-130 parts by weight of water, 100 parts by weight of water-based acrylic resin, 0.5-2 parts by weight of cationic polyvinyl alcohol fiber, 0.5-0.8 parts by weight of defoamer, 0.3-0.5 parts by weight of leveling agent, 20-35 parts by weight of filler, and 0.6-1.2 parts by weight of dispersant.

[0006] The preparation process of water-based anti-corrosion coatings is as follows: (1) Add polyvinyl alcohol fiber and sodium hydroxide to water, stir to activate, add acetone solution containing cyanuric chloride in ice water bath, stir to react, filter and wash the product with ice water and acetone, dry to obtain cyanuric chloride grafted polyvinyl alcohol fiber.

[0007] (2) Add cyanuric chloride-grafted polyvinyl alcohol fiber and trimethylamine aqueous solution to water, stir to react, filter, wash the product with water, and dry to obtain cationic polyvinyl alcohol fiber.

[0008] (3) Add waterborne acrylic resin, cationic polyvinyl alcohol fiber, defoamer, leveling agent, filler and dispersant to water, and disperse them in a shearing machine to obtain waterborne anti-corrosion coating.

[0009] Furthermore, in (1), the temperature for stirring and activation is 20-40℃ and the time is 1-2h.

[0010] Furthermore, in (1), the amount of polyvinyl alcohol fiber is 100 parts by weight, sodium hydroxide is 6-20 parts by weight, and cyanuric chloride is 15-45 parts by weight.

[0011] Furthermore, in (1), the reaction temperature is 5-10℃ and the reaction time is 48-72h.

[0012] Furthermore, in (2), the amount of cyanuric chloride-grafted polyvinyl alcohol fiber is 100 parts by weight, and the amount of trimethylamine is 20-75 parts by weight.

[0013] Furthermore, in (2), the reaction temperature is 50-65℃ and the reaction time is 6-12h.

[0014] Furthermore, the fillers in (3) include silica, titanium dioxide, montmorillonite, and barium sulfate.

[0015] Furthermore, water-based anti-corrosion coatings are used in air conditioning.

[0016] (III) Beneficial technical effects: This invention utilizes the active chlorine atoms of cyanuric chloride to undergo a substitution reaction with the hydroxyl groups on the surface of polyvinyl alcohol to obtain cyanuric chloride-grafted polyvinyl alcohol fibers. The unreacted chlorine atoms then undergo a quaternization reaction with the nitrogen atoms of trimethylamine tertiary amine, thereby introducing a large number of quaternary ammonium salt cations on the surface of polyvinyl alcohol to obtain cationic polyvinyl alcohol fibers. These fibers are then added to water-based acrylic resin to obtain water-based anti-corrosion coatings. The introduction of a large number of hydrophilic quaternary ammonium salt groups on the surface of polyvinyl alcohol fibers significantly improves the dispersibility of polyvinyl alcohol fibers in water-based coatings, making them less prone to aggregation and sedimentation, and maintaining good storage stability of the coating.

[0017] The quaternary ammonium salt cationic groups of the polyvinyl alcohol (PVA) fiber of this invention form an electrostatic interaction with the carboxyl anionic groups in the waterborne acrylic resin. After curing into a paint film, the PVA and acrylic resin form a tight cross-linked network, which can inhibit the entry of corrosive media into the paint film, resulting in better corrosion resistance and salt spray resistance. Furthermore, the compatibility between the two is improved, the impact resistance and pencil hardness of the paint film are increased, and the mechanical properties are enhanced. This makes it suitable for practical applications in air conditioner outdoor unit casings, heat exchanger fins, etc. The nitrogen-rich triazine groups on the surface of the PVA fiber can form chemical coordination with the metal substrate, improving the adhesion between the paint film and the metal substrate, and ensuring good adhesion and detachment resistance of the acrylic resin. Attached Figure Description

[0018] Figure 1 This is the infrared spectrum of cationic polyvinyl alcohol fiber. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The following water-based acrylic resin is a water-based carboxyl acrylic resin with an effective ingredient content of 99%, manufactured by Wuhan Profu Biotechnology Co., Ltd. The polyvinyl alcohol fiber specification is 3mm, model Trunnano PVA, manufactured by Luoyang Tongrun Nanotechnology Co., Ltd. The defoamer model is BASF FoamStar SI 2292. The leveling agent model is Hemings Deqian Waterborne Levaslip W-461. The dispersant model is Evonik ZETASPERSE 3800.

[0021] Example 1: (1) Add 10g of polyvinyl alcohol fiber and 0.6g of sodium hydroxide to 200mL of water, stir and activate at 30°C for 1h, add 25mL of acetone solution containing 1.5g of cyanuric chloride in an ice-water bath, stir and react at 10°C for 48h, filter and wash the product with ice water and acetone, dry to obtain cyanuric chloride grafted polyvinyl alcohol fiber.

[0022] (2) Add 10g of cyanuric chloride-grafted polyvinyl alcohol fiber and 12mL of an aqueous solution containing 2g of trimethylamine to 200mL of water. Stir and reflux at 60℃ for 6h. After filtration, wash the product with water and dry to obtain cationic polyvinyl alcohol fiber. The product was tested, and the results are shown in […]. Figure 1 Among them, 1621-1552cm -1 It is the characteristic peak of the triazine ring in cationic polyvinyl alcohol fibers, 1469 cm⁻¹ -1 It is a quaternary ammonium salt CN + Characteristic peaks of the bond.

[0023] (3) Add 1kg of waterborne acrylic resin, 5g of cationic polyvinyl alcohol fiber, 5g of defoamer, 3g of leveling agent, 320g of barium sulfate and 10g of dispersant to 1.2L of water, and disperse them in a shearing machine to obtain waterborne anti-corrosion coating.

[0024] Example 2: (1) Add 10g of polyvinyl alcohol fiber and 1.1g of sodium hydroxide to 200mL of water, stir and activate at 20°C for 2h, add 40mL of acetone solution containing 2.5g of cyanuric chloride in an ice-water bath, stir and react at 5°C for 72h, filter and wash the product with ice water and acetone, dry to obtain cyanuric chloride grafted polyvinyl alcohol fiber.

[0025] (2) Add 10g of cyanuric chloride-grafted polyvinyl alcohol fiber and 20mL of aqueous solution containing 3.5g of trimethylamine to 200mL of water. Stir and reflux at 65℃ for 6h. After filtration, wash the product with water and dry to obtain cationic polyvinyl alcohol fiber.

[0026] (3) Add 1kg of waterborne acrylic resin, 10g of cationic polyvinyl alcohol fiber, 7g of defoamer, 5g of leveling agent, 200g of titanium dioxide and 6g of dispersant to 0.9L of water, and disperse them in a shearing machine to obtain waterborne anti-corrosion coating.

[0027] Example 3: (1) Add 10g of polyvinyl alcohol fiber and 1.5g of sodium hydroxide to 300mL of water, stir and activate at 20°C for 2h, add 60mL of acetone solution containing 3.5g of cyanuric chloride in an ice-water bath, stir and react at 5°C for 72h, filter and wash the product with ice water and acetone, dry to obtain cyanuric chloride grafted polyvinyl alcohol fiber.

[0028] (2) Add 10g of cyanuric chloride-grafted polyvinyl alcohol fiber and 35mL of aqueous solution containing 5.5g of trimethylamine to 250mL of water. Stir and reflux at 50℃ for 12h. After filtration, wash the product with water and dry to obtain cationic polyvinyl alcohol fiber.

[0029] (3) Add 1kg of waterborne acrylic resin, 15g of cationic polyvinyl alcohol fiber, 7g of defoamer, 4g of leveling agent, 350g of silica and 12g of dispersant to 1.3L of water and disperse them in a shearing machine to obtain waterborne anti-corrosion coating.

[0030] Example 4: (1) Add 10g of polyvinyl alcohol fiber and 2g of sodium hydroxide to 300mL of water, stir and activate at 40°C for 1h, add 80mL of acetone solution containing 4.5g of cyanuric chloride in an ice-water bath, stir and react at 5°C for 72h, filter and wash the product with ice water and acetone, dry to obtain cyanuric chloride grafted polyvinyl alcohol fiber.

[0031] (2) Add 10g of cyanuric chloride-grafted polyvinyl alcohol fiber and 50mL of aqueous solution containing 7.5g of trimethylamine to 300mL of water. Stir and reflux at 55℃ for 10h. After filtration, wash the product with water and dry to obtain cationic polyvinyl alcohol fiber.

[0032] (3) Add 1kg of waterborne acrylic resin, 20g of cationic polyvinyl alcohol fiber, 8g of defoamer, 3g of leveling agent, 280g of montmorillonite and 7g of dispersant to 1.2L of water, and disperse them in a shearing machine to obtain waterborne anti-corrosion coating.

[0033] Comparative Example 1: (1) Add 1 kg of waterborne acrylic resin, 5 g of defoamer, 3 g of leveling agent, 320 g of barium sulfate and 10 g of dispersant to 1.2 L of water and disperse them in a shearing machine to obtain waterborne coating.

[0034] Comparative Example 2: (1) Add 1 kg of waterborne acrylic resin, 5 g of polyvinyl alcohol fiber, 5 g of defoamer, 3 g of leveling agent, 320 g of barium sulfate and 10 g of dispersant to 1.2 L of water and disperse them in a shearing machine to obtain waterborne coating.

[0035] Comparative Example 3: (1) Add 1 kg of waterborne acrylic resin, 5 g of cyanuric chloride grafted polyvinyl alcohol fiber (prepared according to the method of Example 1), 5 g of defoamer, 3 g of leveling agent, 320 g of barium sulfate and 10 g of dispersant to 1.2 L of water and disperse them in a shearing machine to obtain waterborne anti-corrosion coating.

[0036] Comparative Example 4: (1) Add 10g of polyvinyl alcohol fiber and 0.6g of sodium hydroxide to 200mL of water, stir and activate at 30℃ for 1h, add 25mL of acetone solution containing 1.5g of 2,3-epoxypropyltrimethylammonium chloride in an ice-water bath, stir and react at 10℃ for 48h, filter and wash the product with ice water and acetone, dry, and obtain cationic polyvinyl alcohol fiber.

[0037] (2) Add 1 kg of waterborne acrylic resin, 5 g of cationic polyvinyl alcohol fiber, 5 g of defoamer, 3 g of leveling agent, 320 g of barium sulfate and 10 g of dispersant to 1.2 L of water, and disperse them in a shearing machine to obtain waterborne coating.

[0038] The storage stability of the coating was tested according to standard GB / T 6753.3-1986 for 30 days. Salt spray resistance was tested according to standard GB / T 1771-2007, and the formation of the coating film was recorded. Impact resistance was tested according to standard GB / T 1732-1993. Hardness was tested according to standard GB / T 6739-2022. The coating film's resistance to detachment from the substrate and its adhesion were tested according to standard GB / T 9286-2021, with tinplate as the substrate. The performance test results of the coating are shown in Table 1.

[0039] Table 1 Performance of Coatings

[0040] In each embodiment, cationic polyvinyl alcohol (PVA) fibers were incorporated. The introduction of numerous hydrophilic quaternary ammonium salt groups onto the surface of the PVA fibers significantly improved their dispersibility in water-based coatings, reducing the likelihood of aggregation and sedimentation, thus maintaining good storage stability. Simultaneously, the quaternary ammonium salt cationic groups of PVA formed electrostatic interactions with the carboxyl anionic groups in the water-based acrylic resin. After curing into a paint film, the PVA and acrylic resin formed a tight cross-linked network, inhibiting the entry of corrosive media into the film and providing better corrosion resistance and salt spray resistance. Furthermore, the improved compatibility of the two components increased the impact resistance and pencil hardness of the paint film, enhancing its mechanical properties. The nitrogen-rich triazine groups on the surface of the PVA fibers could form chemical coordination with the metal substrate, improving the adhesion between the paint film and the substrate, and maintaining good adhesion and detachment resistance of the acrylic resin.

[0041] Comparative Example 1, which did not contain polyvinyl alcohol fibers, exhibited lower salt spray resistance, impact resistance, and pencil hardness in its coating film. Comparative Examples 2 and 3, lacking quaternary ammonium salt cations, showed poor compatibility with water-based acrylic resins, resulting in lower storage stability, salt spray resistance, impact resistance, and pencil hardness in their coating films. Comparative Example 4 utilized the epoxy groups of 2,3-epoxypropyltrimethylammonium chloride to initiate a ring-opening reaction with the hydroxyl groups on the surface of polyvinyl alcohol fibers. Due to the weak reactivity of the epoxy and hydroxyl groups, the grafting effect of the quaternary ammonium salt cations was affected, leading to fewer quaternary ammonium salt groups on the surface and lower impact resistance and pencil hardness in the coating film.

[0042] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A water-based anti-corrosion coating, characterized in that, The water-based anti-corrosion coating comprises 90-130 parts by weight of water, 100 parts by weight of water-based acrylic resin, 0.5-2 parts by weight of cationic polyvinyl alcohol fiber, 0.5-0.8 parts by weight of defoamer, 0.3-0.5 parts by weight of leveling agent, 20-35 parts by weight of filler, and 0.6-1.2 parts by weight of dispersant; The preparation process of the cationic polyvinyl alcohol fiber is as follows: (1) Add polyvinyl alcohol fiber and sodium hydroxide to water, stir to activate, add acetone solution containing cyanuric chloride in ice water bath, stir to react, filter, wash the product, dry, and obtain cyanuric chloride grafted polyvinyl alcohol fiber. (2) Add cyanuric chloride-grafted polyvinyl alcohol fiber and trimethylamine aqueous solution to water, stir to react, filter, wash the product, and dry to obtain cationic polyvinyl alcohol fiber.

2. The water-based anti-corrosion coating according to claim 1, characterized in that, The filler is any one or more of silica, titanium dioxide, montmorillonite, and barium sulfate.

3. The water-based anti-corrosion coating according to claim 1, characterized in that, The temperature for stirring and activating in (1) is 20-40℃, and the time is 1-2h.

4. The water-based anti-corrosion coating according to claim 1, characterized in that, In (1), the amount of polyvinyl alcohol fiber is 100 parts by weight, sodium hydroxide is 6-20 parts by weight, and cyanuric chloride is 15-45 parts by weight.

5. The water-based anti-corrosion coating according to claim 1, characterized in that, The temperature of the stirring reaction in (1) is 5-10℃ and the reaction time is 48-72h.

6. The water-based anti-corrosion coating according to claim 1, characterized in that, In (2), the amount of cyanuric chloride-grafted polyvinyl alcohol fiber is 100 parts by weight, and the amount of trimethylamine is 20-75 parts by weight.

7. The water-based anti-corrosion coating according to claim 1, characterized in that, The temperature of the stirring reaction in (2) is 50-65℃ and the reaction time is 6-12h.

8. A preparation process for a water-based anti-corrosion coating as described in any one of claims 1-7, characterized in that, The preparation process is as follows: waterborne acrylic resin, cationic polyvinyl alcohol fiber, defoamer, leveling agent, filler, and dispersant are added to water and dispersed in a shearing machine to obtain a waterborne anti-corrosion coating.

9. The application of a water-based anti-corrosion coating obtained by the preparation process described in claim 8 in air conditioning.

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