Stain-resistant internal olefine acid finish paint coating material for refrigerated container and preparation method of stain-resistant internal olefine acid finish paint coating material

Abstract

The invention relates to the technical field of paint, in particular to a stain-resistant internal olefine acid finish paint coating material for a refrigerated container and a preparation method of the stain-resistant internal olefine acid finish paint coating material. Comprising the following preparation raw materials: deionized water, a pH regulator, a high-hydrophobic dispersant, a polyether siloxane defoaming agent containing hydrophobic particles, titanium dioxide, 3000-mesh precipitated barium sulfate, a hydrophobic modified acrylic emulsion, an environment-friendly coalescing agent, a bactericide, a mildew preventive, a high-efficiency emulsion defoaming agent with good compatibility of a polyether siloxane technology, and a non-silicon wetting agent. According to the environment-friendly water-based paint, through the synergistic effect of the super-hydrophobic dispersing agent, the hydrophobic emulsion and the optimized wetting system, the stain resistance close to that of a solvent-based paint is achieved while the water-based environment-friendly advantage is kept; the appearance problem of the refrigerated container is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a stain-resistant acrylic topcoat coating material for refrigerated containers and its preparation method. Background Technology

[0002] As a core piece of equipment in global logistics, refrigerated containers operate in extremely harsh environments, constantly facing challenges such as high salinity and humidity in the ocean, intense ultraviolet radiation, extreme temperature differences, and physical abrasion. Compared to ordinary dry containers, refrigerated containers experience frequent condensation on their outer surfaces during loading and unloading due to the significant temperature difference between the inside and outside. Pollutants such as dust, oil, insect carcasses, and fumes emitted by port machinery readily dissolve in this condensation and penetrate the coating surface and interior. After the moisture evaporates, these form stubborn stains that are difficult to remove, severely affecting the container's appearance and the legibility of its markings, and increasing cleaning and maintenance costs.

[0003] Currently, the mainstream coating technology for refrigerated containers is a system consisting of epoxy zinc-rich primer, epoxy intermediate coat, and acrylic topcoat. While this system is relatively mature in terms of mechanical properties and corrosion resistance, it has significant shortcomings in stain resistance and long-lasting gloss and color retention. Although stain-resistant coatings have been used in the construction industry, their mechanical strength, adhesion, and corrosion resistance cannot meet the extreme mechanical and environmental requirements of refrigerated containers, and their cost-performance ratio is low. Therefore, the market urgently needs a topcoat material specifically designed for refrigerated container operations, possessing excellent stain resistance, high mechanical properties, good weather resistance, and low VOC environmental characteristics to overcome the shortcomings in current practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a stain-resistant acrylic topcoat material for refrigerated containers to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A stain-resistant acrylic topcoat coating material for refrigerated containers, comprising, by weight, the following raw materials: 5-15 parts deionized water, 0.1-0.5 parts pH adjuster, 2-5 parts highly hydrophobic dispersant, 0.3-0.5 parts polyether siloxane defoamer containing hydrophobic particles, 25-30 parts titanium dioxide, 2-5 parts 3000-mesh precipitated barium sulfate, 45-55 parts hydrophobically modified acrylic emulsion, 3-5 parts environmentally friendly film-forming aid, and 0.1 parts bactericide. -0.5 parts, mildew inhibitor 0.1-0.5 parts, high-efficiency emulsion defoamer with good compatibility with polyether siloxane technology 0.3-0.6 parts, non-silicone wetting agent 0.1-0.5 parts, organosilicon modified low-foaming wetting agent 0.1-0.5 parts, acrylic leveling agent 0.1-0.5 parts, anti-flash rust additive 0.1-0.5 parts, high shear thickener 0.1-0.5 parts, low shear thickener 0.1-0.5 parts, water-based general-purpose color paste 0.1-1.0 parts.

[0006] As a further aspect of the present invention: the molecular weight range of the highly hydrophobic dispersant is 10,000-15,000 Daltons; the molecular weight range of the hydrophobic modified acrylic emulsion is 300,000-600,000 Daltons.

[0007] As a further aspect of the present invention, the VOC content of the coating material is less than 5g / L.

[0008] As a further aspect of the present invention, the coating formed after the coating material is applied has the following properties: film thickness 40μm, pencil hardness greater than or equal to H, adhesion grade 0, front impact resistance 50cm without cracking or peeling, water resistance 30 days without change of the paint film, weather resistance 600h without change of the paint film, initial water resistance 7 days without change of the paint film, resistance to 30 cycles of cold and heat without change of the paint film, early rain mark test without rain marks, and stain resistance without pollution.

[0009] A method for preparing a stain-resistant acrylic topcoat coating material for refrigerated containers as described above, the method comprising the following steps: Step 1: Add the prescribed amounts of deionized water, pH adjuster, highly hydrophobic dispersant, polyether siloxane defoamer containing hydrophobic particles, titanium dioxide, and 3000-mesh precipitated barium sulfate sequentially to the mixing tank under stirring conditions. Stir at 1000 rpm for 20 minutes to obtain the premixed slurry. Step 2: Grind the premixed slurry obtained in Step 1 on a sand mill until the fineness is less than 20μm to obtain the pre-dispersion slurry. Step 3: The pre-dispersed slurry obtained in Step 2, along with the formulated amounts of hydrophobic modified acrylic emulsion, environmentally friendly film-forming aid, bactericide, mildew inhibitor, high-efficiency emulsion-type defoamer with good compatibility with polyether siloxane technology, non-silicone wetting agent, organosilicon modified low-foaming wetting agent, acrylic leveling agent, anti-flaking agent, high-shear thickener, low-shear thickener, and water-based general-purpose color paste, are sequentially added to the mixing tank under stirring conditions. The mixture is stirred at high speed at 900 rpm for 20 minutes until it is evenly mixed to obtain the stain-resistant acrylic topcoat coating material.

[0010] As a further aspect of the present invention: in step one, the high-speed stirring speed is 1000 rpm and the stirring time is 20 minutes.

[0011] As a further aspect of the present invention: in step two, the grinding is carried out using a sand mill, and the grinding endpoint is controlled to be a slurry fineness of less than 20μm.

[0012] As a further aspect of the present invention: in step three, the high-speed stirring speed is 900 rpm and the stirring time is 20 minutes.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention possesses excellent stain resistance. Through the synergistic effect of a highly hydrophobic dispersant and a hydrophobically modified acrylic emulsion, a low surface energy coating is constructed, making it difficult for oil stains to wet and adhere, and easily washed away by rainwater. This significantly improves the problem of yellow oil stains on the top and bottom side beams of the container. It also has outstanding early rain streaking resistance. The highly hydrophobic dispersant can effectively lock hydrophilic substances, reduce surface blooming, extend the application window, and solve the problem of yellow droplets appearing after cooling or in light rain. In addition, it has excellent mechanical and protective properties. The coating has high adhesion, high hardness, excellent impact resistance, and good water resistance, corrosion resistance, and resistance to thermal cycling, meeting the harsh physical and environmental tests of refrigerated containers. The use of silicone-modified acrylic emulsion provides excellent UV stability, ensuring that the coating can maintain its performance after long-term outdoor exposure and extending its service life. By optimizing the wetting agent and leveling agent system, the wetting and leveling properties of the coating on the substrate (especially welds and old paint surfaces) are improved, making it suitable for airless spraying equipment in container factories and reducing coating defects. Detailed Implementation

[0014] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0016] In one embodiment of the present invention, a stain-resistant acrylic topcoat coating material for refrigerated containers comprises, by weight, the following raw materials: 5-15 parts deionized water, 0.1-0.5 parts pH adjuster, 2-5 parts highly hydrophobic dispersant, 0.3-0.5 parts polyether siloxane defoamer containing hydrophobic particles, 25-30 parts titanium dioxide, 2-5 parts 3000-mesh precipitated barium sulfate, 45-55 parts hydrophobically modified acrylic emulsion, 3-5 parts environmentally friendly film-forming aid, and 0.1-0.5 parts bactericide. The following components are included: 0.1-0.5 parts of antifungal agent, 0.3-0.6 parts of high-efficiency emulsion defoamer with good compatibility with polyether siloxane technology, 0.1-0.5 parts of non-silicone wetting agent, 0.1-0.5 parts of organosilicon-modified low-foaming wetting agent, 0.1-0.5 parts of acrylic leveling agent, 0.1-0.5 parts of anti-flaking and rusting agent, 0.1-0.5 parts of high-shear thickener, 0.1-0.5 parts of low-shear thickener, and 0.1-1.0 parts of water-based general-purpose colorant. The highly hydrophobic dispersant is BASF's Dispex. CX 4248; the hydrophobically modified acrylic emulsion is Covestro's CS-WL1408; the non-silicone wetting agent is BASF's Hydropalat WE 3323; the organosilicon-modified low-foaming wetting agent is Momentive's CoatOSil 1211C; the acrylic leveling agent is Resos's Enfinol LEV10; the polyether siloxane defoamer containing hydrophobic particles is Evonik's TEGO AIREX 901W; the high-efficiency emulsion-type defoamer with good compatibility with polyether siloxane technology is Evonik's TEGO AIREX 902W; the environmentally friendly film-forming aid is Eastman's TEXANOL ester alcohol.

[0017] In one embodiment of the present invention, the molecular weight of the highly hydrophobic dispersant is in the range of 10,000-15,000 Daltons; and the molecular weight of the hydrophobic modified acrylic emulsion is in the range of 300,000-600,000 Daltons.

[0018] In one embodiment of the present invention, the VOC content of the coating material is less than 5 g / L.

[0019] In one embodiment of the present invention, the coating formed after the coating material is applied has the following properties: film thickness 40μm, pencil hardness greater than or equal to H, adhesion grade 0, frontal impact resistance of 50cm without cracking or peeling, water resistance with no change in the paint film after 30 days, weather resistance with no change in the paint film after 600h, initial water resistance with no change in the paint film after 7 days, resistance to 30 cycles of cold and heat without change in the paint film, no rain streaks in the early rain streak test, and no contamination resistance. One cycle consists of -20℃ for 12h plus 60℃ for 12h.

[0020] A method for preparing the stain-resistant acrylic topcoat coating material for refrigerated containers as described above, characterized in that the method includes the following steps: Step 1: Add the prescribed amounts of deionized water, pH adjuster, highly hydrophobic dispersant, polyether siloxane defoamer containing hydrophobic particles, titanium dioxide, and 3000-mesh precipitated barium sulfate sequentially to the mixing tank under stirring conditions. Stir at 1000 rpm for 20 minutes to obtain the premixed slurry. Step 2: Grind the premixed slurry obtained in Step 1 on a sand mill until the fineness is less than 20μm to obtain the pre-dispersion slurry. Step 3: The pre-dispersed slurry obtained in Step 2, along with the formulated amounts of hydrophobic modified acrylic emulsion, environmentally friendly film-forming aid, bactericide, mildew inhibitor, high-efficiency emulsion-type defoamer with good compatibility with polyether siloxane technology, non-silicone wetting agent, organosilicon modified low-foaming wetting agent, acrylic leveling agent, anti-flaking agent, high-shear thickener, low-shear thickener, and water-based general-purpose color paste, are sequentially added to the mixing tank under stirring conditions. The mixture is then stirred at 900 rpm for 20 minutes until homogeneous, thus obtaining the stain-resistant acrylic topcoat coating material. In one embodiment of the present invention, the [material name missing] is described.

[0021] In one embodiment of the present invention, in step one, the high-speed stirring speed is 1000 rpm and the stirring time is 20 minutes.

[0022] In one embodiment of the present invention, in step two, the grinding is carried out using a sand mill, and the grinding endpoint is controlled to be a slurry fineness of less than 20 μm.

[0023] In one embodiment of the present invention, in step three, the high-speed stirring speed is 900 rpm and the stirring time is 20 minutes.

[0024] The basic formulation was basically the same as that in the examples, but the highly hydrophobic dispersant (Dispex CX 4248) was replaced with a conventional hydrophobic modified polyurethane dispersant, and the silicone modified low-foaming wetting agent was replaced with a conventional acetylenic diol wetting agent to obtain the comparative example.

[0025] The topcoats prepared in the examples and comparative examples were applied to treated cold-rolled steel sheets and actual refrigerated container test pieces according to standard methods. The dry film thickness was controlled at 40±5μm. After curing under specified conditions, various performance tests were conducted, and the results are compared as follows: Test Project Example Comparative Example Pencil hardness H HB Adhesion Level 0 Level 1 Impact resistance (1kg×50cm) pass minor cracks Early rain stain resistance (24h) No rain streaks Obvious rain streaks Stain resistance (engine oil, after wiping) Extremely easy to wipe off, leaves no trace There are obvious traces of residue Water resistance (30 days) No change Slight loss of luster, whitening VOC content (g / L) 4.2 4.5 Test results show that the topcoat provided by the embodiments of the present invention is significantly better than the comparative example in key properties such as stain resistance, early rain streaks resistance, hardness and adhesion, which fully demonstrates the superiority and synergistic effect of the formulation design of the present invention.

[0026] This refrigerated container uses a stain-resistant acrylic topcoat material. Through superhydrophobic modification, optimized wetting properties, and synergistic stain resistance, it achieves stain resistance close to that of solvent-based coatings while maintaining the environmental advantages of water-based coatings, effectively solving the appearance problems of refrigerated containers. During film formation, the hydrophobic groups of the highly hydrophobic dispersant and hydrophobically modified acrylic emulsion migrate to the coating surface, jointly constructing a low surface energy (<20 mN / m) surface, making it difficult for oil stains to wet, adhering only as droplets, and easily removed. The optimized combination of silicone-modified low-foaming wetting agent with non-silicone wetting agent and acrylic leveling agent not only ensures good wetting of the substrate during construction and avoids defects, but also enhances the overall water resistance of the coating after curing through its dynamic migration, reducing the residue of hydrophilic groups. The low surface energy surface effectively repels oil stains; the silicone-modified resin provides excellent UV stability, delays aging, and ensures that the long-term stain resistance does not decline.

[0027] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A stain-resistant acrylic topcoat coating material for refrigerated containers, characterized in that, The preparation materials, by weight, include the following: 5-15 parts deionized water, 0.1-0.5 parts pH adjuster, 2-5 parts highly hydrophobic dispersant, 0.3-0.5 parts polyether siloxane defoamer containing hydrophobic particles, 25-30 parts titanium dioxide, 2-5 parts 3000-mesh precipitated barium sulfate, 45-55 parts hydrophobically modified acrylic emulsion, 3-5 parts environmentally friendly film-forming aid, 0.1-0.5 parts bactericide, and 0 parts mildew inhibitor. 0.1-0.5 parts, 0.3-0.6 parts of high-efficiency emulsion defoamer with good compatibility with polyether siloxane technology, 0.1-0.5 parts of non-silicone wetting agent, 0.1-0.5 parts of organosilicon modified low-foaming wetting agent, 0.1-0.5 parts of acrylic leveling agent, 0.1-0.5 parts of anti-flash rust additive, 0.1-0.5 parts of high shear thickener, 0.1-0.5 parts of low shear thickener, and 0.1-1.0 parts of water-based general-purpose color paste.

2. The stain-resistant acrylic topcoat coating material for refrigerated containers according to claim 1, characterized in that, The highly hydrophobic dispersant has a molecular weight range of 10,000-15,000 Daltons; the hydrophobic modified acrylic emulsion has a molecular weight range of 300,000-600,000 Daltons.

3. The stain-resistant acrylic topcoat coating material for refrigerated containers according to claim 2, characterized in that, The VOC content of the coating material is less than 5 g / L.

4. The stain-resistant acrylic topcoat coating material for refrigerated containers according to claim 3, characterized in that, The coating formed after the coating material is applied has the following properties: film thickness 40μm, pencil hardness greater than or equal to H, adhesion grade 0, front impact resistance 50cm without cracking or peeling, water resistance 30 days without change of the paint film, weather resistance 600h without change of the paint film, initial water resistance 7 days without change of the paint film, resistance to 30 cycles of cold and heat without change of the paint film, early rain mark test without rain marks, and stain resistance without pollution.

5. A method for preparing a stain-resistant acrylic topcoat coating material for refrigerated containers as described in any one of claims 1-4, characterized in that, The method includes the following steps: Step 1: Add the prescribed amounts of deionized water, pH adjuster, highly hydrophobic dispersant, polyether siloxane defoamer containing hydrophobic particles, titanium dioxide, and 3000-mesh precipitated barium sulfate sequentially to the mixing tank under stirring conditions. Stir at 1000 rpm for 20 minutes to obtain the premixed slurry. Step 2: Grind the premixed slurry obtained in Step 1 on a sand mill until the fineness is less than 20μm to obtain the pre-dispersion slurry. Step 3: The pre-dispersed slurry obtained in Step 2, along with the formulated amounts of hydrophobic modified acrylic emulsion, environmentally friendly film-forming aid, bactericide, mildew inhibitor, high-efficiency emulsion-type defoamer with good compatibility with polyether siloxane technology, non-silicone wetting agent, organosilicon modified low-foaming wetting agent, acrylic leveling agent, anti-flaking agent, high-shear thickener, low-shear thickener, and water-based general-purpose color paste, are sequentially added to the mixing tank under stirring conditions. The mixture is stirred at high speed at 900 rpm for 20 minutes until it is evenly mixed to obtain the stain-resistant acrylic topcoat coating material.

6. The method for preparing the stain-resistant acrylic topcoat material for refrigerated containers according to claim 5, characterized in that, In step one, the high-speed stirring speed is 1000 rpm and the stirring time is 20 minutes.

7. The method for preparing the stain-resistant acrylic topcoat material for refrigerated containers according to claim 5, characterized in that, In step two, the grinding is carried out using a sand mill, and the grinding endpoint is controlled to be a slurry fineness of less than 20μm.

8. The method for preparing the stain-resistant acrylic topcoat coating material for refrigerated containers according to claim 5, characterized in that, In step three, the high-speed stirring speed is 900 rpm and the stirring time is 20 minutes.