A pore-forming in-situ porous coating and methods of making and using the same

Abstract

The application provides a porous coating formed in situ and a preparation method and application thereof, and belongs to the technical field of polymer materials. The porous coating is prepared by coating a slurry of polyvinyl chloride resin on the surface of a substrate in a specific manner, pretreating the slurry to make the slurry adhere to the surface of the substrate to form a film, and then pyrolyzing the film to etch and decompose the polyvinyl chloride according to a specific technical route, and cooling, thereby obtaining the porous coating. The application provides a preparation method of the porous coating formed in situ. The preparation method is simple, does not need to use expensive equipment and reagents, and has a very obvious cost advantage. The preparation method does not need to rely on any organic solvent and does not need a pore-forming agent, and is very friendly to the environment. The porous coating obtained by the preparation method has a smooth surface, rich pores, high porosity, stable structure, strong adhesion to the substrate, high adsorption rate, excellent performance, and is suitable for multiple fields. The porous coating is very suitable for popularization and mass production, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an in-situ porous coating, its preparation method, and its applications. Background Technology

[0002] Porous coatings are increasingly widely used in fields such as supercapacitors, lithium battery electrodes, automotive exhaust treatment, chemical catalytic reactions, air purification, water treatment, drug carriers, microwave absorbing materials, and aerospace due to their unique structural advantages, such as high specific surface area, low density, good adsorption, permeability, and microscopic storage performance.

[0003] There are various methods for preparing porous coatings, including spraying, sol-gel, anodizing, electrochemical deposition, template methods, 3D printing, biotemplate methods, and vapor deposition. Among these, spraying requires expensive equipment, demands high precision, consumes a lot of energy, and generates dust that is environmentally unfriendly; the sol-gel method requires large amounts of organic solvents, resulting in significant emissions of volatile organic compounds (VOCs); anodizing requires specialized equipment, has strict process requirements, and presents challenges in treating electrolyte waste; electrochemical deposition requires the use of precious metals, leading to high costs, and also involves the use of toxic electrolytes containing cyanides, making wastewater treatment difficult; template methods involve template waste that is difficult to degrade; 3D printing equipment is expensive; biotemplate methods involve high costs related to biological culture; and vapor deposition has extremely high equipment maintenance costs, demanding process conditions, requires the use of toxic solvents, and has a complex waste gas treatment system. It is evident that existing methods for preparing porous coatings generally suffer from problems such as high preparation costs, complex processes, demanding equipment requirements, heavy reliance on organic solvents, high energy consumption, and difficulty in meeting environmental standards. Consequently, they face numerous obstacles in their promotion and mass production.

[0004] Polyvinyl chloride (PVC) resin is often used to prepare coatings due to its low cost, wide availability, and easy processing. However, it is difficult to prepare porous coating materials from PVC alone. It is necessary to achieve the porous structure of the coating through physical / chemical modification or composite processes. However, these methods also have the above-mentioned problems. For example: (1) Solvent evaporation / phase separation method: PVC is dissolved in an organic solvent (such as tetrahydrofuran or cyclohexanone), a pore-forming agent (such as PEG or salt particles) is added, the solvent is evaporated and the pore-forming agent is removed after coating to form a porous structure. However, this method depends on organic solvents, which are highly toxic and difficult to meet environmental protection standards; (2) Thermal phase separation method: PVC is dissolved in a plasticizer (such as phthalates) at high temperature. After cooling, the plasticizer precipitates to form pores. However, this method has high energy consumption and the plasticizer residue may affect environmental protection; (3) Foaming method: adding chemical Foaming agents (such as azodicarbonamide) or supercritical CO2 foaming are used to generate gas to form pores by heating and decomposition. This method is complex and requires high-pressure equipment; (4) Electrospinning: PVC is dissolved in a DMF / acetone mixed solvent and high-pressure electrospinning is used to form a porous network of nanofibers. However, the solvent in this method is highly toxic; (5) Template method (sacrificial template): PVC is mixed with a soluble template (such as NaCl particles). After molding, the template is dissolved to create pores. However, incomplete removal of the template may block the pores. At the same time, the process involves many steps and is costly.

[0005] How to provide a porous coating that is low-cost, simple to implement, environmentally friendly, produces abundant pores, and has good performance is a problem that urgently needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide an in-situ porous coating, its preparation method, and its applications.

[0007] This invention provides a porous coating with in-situ pore formation. It is made by coating a polyvinyl chloride resin slurry onto the surface of a substrate, pretreating it at 40-80°C to allow the slurry to adhere to the substrate surface and form a film, and then pyrolyzing it at 200-400°C to etch and decompose the polyvinyl chloride into pores, followed by cooling to obtain the coating.

[0008] Furthermore, the pretreatment time at 40–80°C is 30–200 minutes; and / or, the pyrolysis time at 200–400°C is 20–120 minutes.

[0009] Furthermore, the slurry is uniformly dispersed from the following components: polyvinyl chloride resin, film-forming substance, accelerator, leveling agent, and filler;

[0010] Preferably, the slurry is formed by uniformly dispersing the following components in the indicated weight ratios:

[0011] 10-80 parts of polyvinyl chloride resin, 10-50 parts of film-forming substance, 1-20 parts of accelerator, 1-10 parts of leveling agent, and 3-30 parts of filler.

[0012] Furthermore,

[0013] The accelerator is selected from one or more of MgO, ZnO, CaO, Fe2O3, MnO2, Co2O3, and CuO. Alternatively, the accelerator may be selected from a combination of ZnO, Fe2O3, Co2O3, CaO, and MnO2, or a combination of CuO and MgO.

[0014] And / or, the filler is selected from one or more of CaCO3, SiO2, carbon black, graphite, carbon nanotubes, glass fiber, carbon fiber, and mica.

[0015] Furthermore, the substrate is a high-temperature resistant substrate; preferably, the high-temperature resistant substrate is a metal or non-metal high-temperature resistant material. More preferably, the metal is Al or Cu, etc.

[0016] The present invention also provides a method for preparing the aforementioned porous coating, which includes the following steps:

[0017] (1) Weigh each component of the slurry according to the weight ratio, disperse each component evenly, and obtain the slurry;

[0018] (2) After coating the slurry onto the substrate surface, pre-treat it at 40-80℃ to allow the slurry to adhere to the substrate surface and form a film. Then, pyrolyze it at 200-400℃ to decompose the polyvinyl chloride and etch it into pores. Cool it to room temperature to obtain a porous coating.

[0019] Preferably, in step (2), the pretreatment time at 40-80°C is 30-200 minutes; and / or, the pyrolysis time at 200-400°C is 20-120 minutes.

[0020] This invention also provides applications of the aforementioned porous coating in supercapacitors, lithium battery electrodes, automotive exhaust treatment, chemical catalytic reactions, air purification, water treatment, drug carriers, microwave absorbing materials, and aerospace.

[0021] The present invention also provides a slurry for preparing porous coatings, which is composed of the following components uniformly dispersed: polyvinyl chloride resin, film-forming substance, accelerator, leveling agent, and filler;

[0022] Preferably, it is composed of components in the following weight ratio that are uniformly dispersed:

[0023] 10-80 parts of polyvinyl chloride resin, 10-50 parts of film-forming substance, 1-20 parts of accelerator, 1-10 parts of leveling agent, and 3-30 parts of filler.

[0024] Furthermore,

[0025] The accelerator is selected from one or more of MgO, ZnO, CaO, Fe2O3, MnO2, Co2O3, and CuO. Alternatively, the accelerator may be selected from a combination of ZnO, Fe2O3, Co2O3, CaO, and MnO2, or a combination of CuO and MgO.

[0026] And / or, the filler is selected from one or more of CaCO3, SiO2, carbon black, graphite, carbon nanotubes, glass fiber, carbon fiber, and mica.

[0027] The present invention also provides the use of the aforementioned slurry for preparing porous coatings with in-situ pores.

[0028] In this invention, the film-forming substance refers to a polymer emulsion or solution that can uniformly disperse PVC resin, accelerator, leveling agent, and filler to form a uniform coating slurry and can firmly adhere the coating slurry to the substrate. It is one of the key components of the coating slurry. Examples of film-forming substances that can achieve the in-situ porous coating preparation of this invention include polyester aqueous emulsions, polyacrylate aqueous emulsions, polyurethane aqueous emulsions, epoxy resin aqueous emulsions, rubber-based aqueous emulsions, and polyvinyl alcohol aqueous solutions. Furthermore, the inventors have discovered that, not limited to the types of film-forming substances mentioned above, other polymer emulsions or solutions in the art can also be used as film-forming substances in this invention to achieve the preparation of in-situ porous coatings.

[0029] In this invention, the leveling agent plays a crucial role in ensuring that the PVC coating forms a smooth, uniform film during the drying process, thus contributing significantly to the preparation of a perfect porous coating. Silicone-based, acrylic-based, fluorocarbon-based, polyester-based, and polyurethane-based leveling agents are all suitable for achieving the in-situ porous coating preparation of this invention. Furthermore, the inventors have discovered that, beyond the aforementioned types of leveling agents, other leveling agents in the art can also be used as components of the coating slurry of this invention to achieve the preparation of an in-situ porous coating.

[0030] Among polymer materials, polyvinyl chloride (PVC) resin possesses a unique characteristic of being extremely heat-sensitive. PVC decomposes and etches at relatively low temperatures, with the rate of decomposition and etching accelerating at higher temperatures. Furthermore, under certain conditions, this decomposition and etching can be controlled, meaning they proceed according to a designed mechanism. In addition, PVC resin possesses a unique "natural multi-layered, porous" garnet structure, which makes it an ideal material for in-situ pore formation. This invention fully utilizes these characteristics of PVC resin to design and obtain a porous coating with in-situ pores, a technique never before reported in existing technology. Through design, this invention preserves the garnet structure of PVC resin while allowing the residual resin after controlled thermal degradation and etching to appear in situ as a cross-linked conjugated polyolefin structure, resulting in not only abundant pores but also a stable porous structure.

[0031] The present invention has achieved the following beneficial effects:

[0032] This invention, based on the porous garnet structure of PVC resin and its characteristics of being thermally intolerant yet capable of controlled decomposition, innovatively proposes a method for preparing a porous coating with in-situ pore formation. This preparation method is simple, requires no expensive equipment or reagents, and offers a significant cost advantage. Furthermore, it does not rely on any organic solvents or pore-forming agents, making it environmentally friendly. The porous coating obtained using this method exhibits a smooth surface, abundant pores, high porosity, stable structure, strong adhesion to substrates, high adsorption rate, and excellent performance, making it suitable for multiple fields. This porous coating is highly suitable for widespread adoption and mass production, and has promising application prospects.

[0033] Obviously, based on the above description of the present invention, and according to the well-known knowledge and technical means in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0034] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Detailed Implementation

[0035] The raw materials and equipment used in this invention are either self-synthesized or known products, and the known products are obtained by purchasing commercially available products.

[0036] Example 1: Preparation of the in-situ porous coating of the present invention

[0037] Take 80g of polyvinyl chloride resin (SG8, Yibin Tianyuan), 10g of polyester aqueous emulsion (BW-7013, Hubei Kodiya Technology Co., Ltd.), 6g of ZnO, 1g of TEGO Glide 410, and 3g of CaCO3, and place them in a high-speed disperser. Disperse at high speed for 100min to obtain a polyvinyl chloride resin slurry. Coat the slurry onto a clean Al sheet. Then place the Al sheet in a muffle furnace, heat the furnace to 80℃ and maintain the temperature for 30 minutes, then continue heating to 320℃ and maintain the temperature for 60 minutes. Remove the sheet from the muffle furnace and immediately place it in a desiccator to cool to room temperature to obtain an in-situ porous coating.

[0038] Example 2: Preparation of the in-situ porous coating of the present invention

[0039] Take 10g of polyvinyl chloride resin (SG3, Yibin Tianyuan), 50g of acrylate aqueous emulsion (ADY-602, Hubei Kodiya Technology Co., Ltd.), 10.5g of CuO, 4.5g of MgO, 5g of CTT-25, and 20g of SiO2, and place them in a high-speed disperser. Disperse at high speed for 180min to obtain a polyvinyl chloride resin slurry. Coat the slurry onto a clean Cu sheet. Then place the Cu sheet in a muffle furnace, heat the muffle furnace to 40℃ and maintain the temperature for 200min, then continue to heat to 200℃ and maintain the temperature for 110min. Remove the sheet from the muffle furnace and immediately place it in a desiccator to cool to room temperature to obtain an in-situ porous coating.

[0040] Example 3: Preparation of the in-situ porous coating of the present invention

[0041] Take 48g of polyvinyl chloride resin (SG5, Yibin Tianyuan), 22g of polyvinyl alcohol aqueous solution (1788, Sichuan Vinylon Factory), 10g of Co2O3, 8g of CaO, 2g of MnO2, 4g of EFKA-3777, and 6g of carbon nanotubes, and place them in a high-speed disperser. Disperse at high speed for 70 minutes to obtain a polyvinyl chloride resin slurry. Coat the slurry onto a clean Al sheet. Then place the Al sheet in a muffle furnace, heat the muffle furnace to 60℃ and maintain the temperature for 150 minutes, then continue to heat to 260℃ and maintain the temperature for 120 minutes. Remove the sheet from the muffle furnace and immediately place it in a desiccator to cool to room temperature to obtain an in-situ porous coating.

[0042] Example 4: Preparation of the in-situ porous coating of the present invention

[0043] Take 26g of polyvinyl chloride resin (SG8, Yibin Tianyuan), 33g of polyurethane aqueous emulsion (BW-8652, Hubei Kodiya Technology Co., Ltd.), 1g of Fe2O3, 5.5g of BYK-333, 4.5g of STA-3333A, and 30g of glass fiber, and place them in a high-speed disperser. Disperse at high speed for 120 minutes to obtain a polyvinyl chloride resin slurry. Coat the slurry onto a clean Cu sheet. Then place the Cu sheet in a muffle furnace, heat the muffle furnace to 70℃ and maintain the temperature for 90 minutes, then continue to heat to 400℃ and maintain the temperature for 20 minutes. Remove the sheet from the muffle furnace and immediately place it in a desiccator to cool to room temperature to obtain an in-situ porous coating.

[0044] The following specific experimental examples demonstrate the beneficial effects of the present invention.

[0045] Performance characterization of in-situ porous coatings in Experimental Example 1 and Examples 1-4

[0046] 1. Experimental Methods

[0047] The properties of the in-situ porous coatings prepared in Examples 1-4 were characterized as follows:

[0048] (1) Visual inspection: Observe the appearance of the coating with the naked eye to see if the surface is flat.

[0049] (2) Porosity determination: The porosity of each coating was determined by mercury porosimetry, and the testing standard was ISO 15901-1:2016.

[0050] (3) Adsorption rate determination: The adsorption rate of each coating was determined by weighing. The weight of a dry, impurity-free coating sample (G1) was weighed, and then the coating sample was placed in a constant temperature and humidity chamber at 60% humidity and 25℃. After 24 hours, the coating sample was removed, and the weight of the coated sample after adsorption (G2) was immediately weighed. The adsorption rate of the coating was calculated.

[0051] 2. Experimental Results

[0052] The performance characterization results of the in-situ porous coatings in Examples 1-4 are shown in Table 1.

[0053] Table 1. Performance characterization results of in-situ porous coatings in Examples 1-4

[0054] Appearance Porosity Adsorption rate (humidity 60% / 25℃ / 24h) Example 1 Smooth surface, no warping 56％ 9.3％ Example 2 Smooth surface, no warping 45％ 8.7％ Example 3 Smooth surface, no warping 63％ 15.8％ Example 4 Smooth surface, no warping 48％ 10.5％

[0055] As shown in Table 1, the in-situ porous coatings prepared by the present invention have smooth surfaces, no warping, and high porosity and adsorption rate. The coating prepared in Example 3 is the best.

[0056] In summary, this invention, based on the porous garnet structure of PVC resin and its characteristics of being thermally intolerant yet capable of controlled decomposition, innovatively proposes a method for preparing a porous coating with in-situ pore formation. This preparation method is simple, requires no expensive equipment or reagents, and offers a significant cost advantage. Furthermore, it does not rely on any organic solvents or pore-forming agents, making it environmentally friendly. The porous coating obtained using this method exhibits a smooth surface, abundant pores, high porosity, stable structure, strong adhesion to substrates, high adsorption rate, and excellent performance, making it suitable for multiple fields. This porous coating is highly suitable for widespread adoption and mass production, and has promising application prospects.

Claims

1. A porous coating with in-situ pore formation, characterized in that: It is prepared by coating a polyvinyl chloride resin slurry onto the surface of a substrate, pre-treating it at 40-80℃ to allow the slurry to adhere to the substrate surface and form a film, then pyrolyzing it at 200-400℃ to etch and decompose the polyvinyl chloride into pores, and finally cooling it.

2. The porous coating according to claim 1, characterized in that: The pretreatment time at 40–80°C is 30–200 minutes; and / or the pyrolysis time at 200–400°C is 20–120 minutes.

3. The porous coating according to claim 1 or 2, characterized in that: The slurry is composed of the following components dispersed uniformly: polyvinyl chloride resin, film-forming substance, accelerator, leveling agent, and filler; Preferably, the slurry is formed by uniformly dispersing the following components in the indicated weight ratios: 10-80 parts of polyvinyl chloride resin, 10-50 parts of film-forming substance, 1-20 parts of accelerator, 1-10 parts of leveling agent, and 3-30 parts of filler.

4. The in-situ porous coating according to claim 3, characterized in that: The accelerator is selected from one or more of MgO, ZnO, CaO, Fe2O3, MnO2, Co2O3, and CuO; And / or, the filler is selected from one or more of CaCO3, SiO2, carbon black, graphite, carbon nanotubes, glass fiber, carbon fiber, and mica.

5. The porous coating according to claim 1 or 2, characterized in that: The substrate is a high-temperature resistant substrate; preferably, the high-temperature resistant substrate is a metal or non-metal high-temperature resistant material.

6. The method for preparing the porous coating according to any one of claims 1 to 5, characterized in that: It includes the following steps: (1) Weigh each component of the slurry according to the weight ratio, disperse each component evenly, and obtain the slurry; (2) After coating the slurry onto the substrate surface, pre-treat it at 40-80℃ to allow the slurry to adhere to the substrate surface and form a film. Then, pyrolyze it at 200-400℃ to decompose the polyvinyl chloride and etch it into pores. Cool it to room temperature to obtain a porous coating. Preferably, in step (2), the pretreatment time at 40-80°C is 30-200 minutes; and / or, the pyrolysis time at 200-400°C is 20-120 minutes.

7. The use of the porous coating according to any one of claims 1 to 5 in supercapacitors, lithium battery electrodes, automobile exhaust treatment, chemical catalytic reactions, air purification, water treatment, drug carriers, microwave absorbing materials, and aerospace fields.

8. A slurry for preparing porous coatings, characterized in that: It is composed of the following components dispersed uniformly: polyvinyl chloride resin, film-forming substance, accelerator, leveling agent, and filler; Preferably, it is composed of components in the following weight ratio that are uniformly dispersed: 10-80 parts of polyvinyl chloride resin, 10-50 parts of film-forming substance, 1-20 parts of accelerator, 1-10 parts of leveling agent, and 3-30 parts of filler.

9. The slurry according to claim 8, characterized in that: The accelerator is selected from one or more of MgO, ZnO, CaO, Fe2O3, MnO2, Co2O3, and CuO; And / or, the filler is selected from one or more of CaCO3, SiO2, carbon black, graphite, carbon nanotubes, glass fiber, carbon fiber, and mica.

10. Use of the slurry according to claim 8 or 9 for preparing a porous coating with in-situ pores.

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