Manufacturing process of super-hydrophobic aluminum foil with composite coating

Abstract

The invention belongs to the technical field of air conditioner refrigeration and materials, and particularly relates to a manufacturing process of a super-hydrophobic aluminum foil with a composite coating, the composite coating of the super-hydrophobic aluminum foil is formed by compounding polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powder, and the super-hydrophobic aluminum foil has high corrosion resistance and has good bonding force with an aluminum base material, so that the super-hydrophobic aluminum foil is formed. Meanwhile, polyphenylene sulfide (PPS) which has certain binding power with polytetrafluoroethylene (PTFE) is used as an intermediate medium, and the intermediate medium is firstly coated on the surface of the aluminum foil; then, polytetrafluoroethylene (PTFE) powder is coated on the surface of the polyphenylene sulfide (PPS) coating, and is adhered to the polyphenylene sulfide (PPS) coating under the assistance of a hot embedding technology, so that a composite coating consisting of the polyphenylene sulfide (PPS) and the polytetrafluoroethylene (PTFE) is formed; therefore, the aluminum foil which has super-hydrophobic performance, strong corrosion resistance and self-cleaning performance and is used for refrigeration and air conditioning products is obtained so as to comprehensively improve the comprehensive performance of aluminum foil fins of surface heat exchangers used in the field of refrigeration and air conditioning.

Description

Technical Field

[0001] The invention relates to the technical field of air conditioning, refrigeration and materials, and in particular to a manufacturing process of a super-hydrophobic aluminum foil with a composite coating. Background Art

[0002] At present, the fins of surface heat exchangers used in the field of refrigeration and air conditioning are mainly made of hydrophilic aluminum foil, which is a base aluminum product coated with acrylic resin hydrophilic material. The main function of the acrylic resin coating is to make the moisture in the hot air condense into water droplets on the heat exchanger fins and spread out easily and flow down along the sheet. This can prevent the water droplets between the heat exchanger fins from growing and "bridge" between the fins, thereby improving the heat exchange rate of the air conditioner heat exchanger.

[0003] Hydrophobic aluminum foil is also called water-repellent aluminum foil or water-repellent aluminum foil. The surface properties of hydrophobic aluminum foil are just the opposite of those of hydrophilic aluminum foil. That is, when condensed water condenses on the surface of the aluminum foil, the contact angle between the aluminum foil and the foil is larger. The larger the angle, the better the water repellency. The ultimate purpose of using hydrophobic aluminum foil is the same as that of hydrophilic aluminum foil, that is, to prevent condensed water from accumulating between the heat exchanger plates. The difference is that hydrophobic aluminum foil increases the contact angle between the condensed water and the heat exchanger plates, so that the condensed water forms fine water droplets that are easy to slide off, thereby achieving the purpose of timely removing the condensed water between the heat exchanger plates.

[0004] Polytetrafluoroethylene (PTFE), also known as Teflon, is a polymer compound made by polymerizing tetrafluoroethylene. Polytetrafluoroethylene has excellent chemical stability, corrosion resistance, sealing, high lubricity and non-stickiness, electrical insulation and good anti-aging resistance. The surface energy of polytetrafluoroethylene is extremely low, so it has super hydrophobic properties. Polyphenylene sulfide (PPS) is a new type of high-performance thermoplastic resin with the advantages of corrosion resistance (corrosion resistance is close to polytetrafluoroethylene), high mechanical strength, high temperature resistance, and chemical resistance (second only to polytetrafluoroethylene). It not only has good adhesion to metal substrates, but also has a certain adhesion to polytetrafluoroethylene.

[0005] As can be seen from the above, for the fin-tube heat exchanger of refrigeration and air-conditioning equipment, when the heat exchange on one side of the fin is condensed, large water droplets are often formed on the fin and a liquid bridge is generated between them, which not only increases the thermal resistance of the heat exchanger fin, but also hinders the flow of gas and increases its flow resistance. In order to avoid this liquid bridge effect, people have to apply hydrophilic coating on the surface of the air-conditioning fin so that the condensed water can cover the entire fin surface in the form of a water film to avoid the formation of water droplets and their liquid bridges. However, although the surface coating of hydrophilic coating can solve the above-mentioned liquid bridge problem, the water film formed on the fin and the influence of the water film on its heat exchange and gas channel also bring certain negative effects to its heat transfer. Although polytetrafluoroethylene has a series of excellent properties such as super hydrophobicity, strong corrosion resistance, certain frost inhibition and self-cleaning, it is difficult to bond with metal substrates due to its extremely low surface energy, so there are great obstacles in the application of refrigeration and air-conditioning aluminum foil.

[0006] At present, there are a large number of reports on patented technologies for super-hydrophobic aluminum foils in China, and the preparation technologies for super-hydrophobic aluminum surfaces are also diverse. Among them are: composite method, sandblasting method, plasma etching method, sol-gel method, thermal oxidation method, anodizing template method, one-step immersion method, etc. However, all these methods are either due to the high preparation cost caused by the complexity of the ingredients, production process and equipment of hydrophobic materials (such as plasma treatment method and anodizing template method), or due to the large pollution to the environment (such as etching method), or due to the low preparation efficiency (such as thermal oxidation method), etc., which greatly restricts their production and application, resulting in no large-scale promotion and application so far.

[0007] Therefore, a process for preparing a composite-coated super-hydrophobic aluminum foil is proposed to solve the above-mentioned problems. Summary of the invention

[0008] The object of the present invention is to provide a process for preparing a super-hydrophobic aluminum foil with a composite coating to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a process for preparing a composite coating of super-hydrophobic aluminum foil, wherein the composite coating of the super-hydrophobic aluminum foil is prepared by compounding polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powder, and the specific steps of the preparation process are as follows: Step 1: Select an aluminum foil substrate, prepare a cleaning solution, heat the cleaning solution by a heating device until the temperature of the cleaning solution rises to 50-60°C, and then clean the surface of the aluminum foil substrate by the cleaning solution; Step 2: Dry the cleaned aluminum foil. After the aluminum foil substrate is cleaned, dry it at a temperature of 60-80°C for 6-8 minutes. After the aluminum foil is dried, coat the surface with polyphenylene sulfide. The coating thickness is controlled at 1-2um. Step 3: Place the aluminum foil coated with polyphenylene sulfide in the drying device, adjust the temperature of the drying device to 180-280°C, dry for 3-5 minutes to a semi-dry state, and then coat the aluminum foil with tetrafluoroethylene powder in this state, with the coating thickness controlled to 1-1.5um; Step 4: compact the aluminum foil coated with tetrafluoroethylene powder, place it in a drying device after compaction, control the temperature of the drying device at 160-200°C, continue drying for 8-12 minutes, take it out after drying, cool it to room temperature and roll it up.

[0010] Preferably, the cleaning solution is NMP (N-methylpyrrolidone).

[0011] Preferably, the polyphenylene sulfide is coated on the outside of the aluminum foil by roller coating or dip coating.

[0012] Preferably, the tetrafluoroethylene powder is coated on the outside of the aluminum foil by roller coating, dip coating or spray coating.

[0013] Preferably, the specific method of the step 1 cleaning is to place the cleaning liquid into a pool, and soak the aluminum foil substrate in the cleaning liquid for 6-10 minutes.

[0014] Preferably, in step 4, the method for compacting the tetrafluoroethylene powder coated on the surface of the aluminum foil is a molding method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: By using polyphenylene sulfide (PPS) which has strong anti-corrosion performance, good adhesion to aluminum substrate and certain adhesion to polytetrafluoroethylene (PTFE) as an intermediate medium, it is first coated on the surface of aluminum foil, and then polytetrafluoroethylene (PTFE) powder is coated on the surface of the polyphenylene sulfide (PPS) coating and assisted by hot embedding technology to achieve adhesion between it and the polyphenylene sulfide (PPS) coating, thereby forming a composite coating composed of polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE), thereby obtaining an aluminum foil for refrigeration and air-conditioning products with super hydrophobicity, strong anti-corrosion performance and self-cleaning performance, so as to comprehensively improve the comprehensive performance of aluminum foil fins of surface heat exchangers used in the refrigeration and air-conditioning fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention.

[0017] In the figure: 1 aluminum foil substrate, 2 polyphenylene sulfide coating, 3 polytetrafluoroethylene coating. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] See also Figure 1 , the present invention provides a technical solution: A process for manufacturing a composite coating of super-hydrophobic aluminum foil, wherein the composite coating of the super-hydrophobic aluminum foil is composited with polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powders, and the specific steps of the manufacturing process are as follows: Step 1: Select an aluminum foil substrate, prepare a cleaning solution, heat the cleaning solution by a heating device until the temperature of the cleaning solution rises to 50-60°C, and then clean the surface of the aluminum foil substrate by the cleaning solution; Step 2: Dry the cleaned aluminum foil. After the aluminum foil substrate is cleaned, dry it at a temperature of 60-80°C for 6-8 minutes. After the aluminum foil is dried, coat the surface with polyphenylene sulfide. The coating thickness is controlled at 1-2um. Step 3: Place the aluminum foil coated with polyphenylene sulfide in the drying device, adjust the temperature of the drying device to 180-280°C, dry for 3-5 minutes to a semi-dry state, and then coat the aluminum foil with tetrafluoroethylene powder in this state, with the coating thickness controlled to 1-1.5um; Step 4: Compact the aluminum foil coated with tetrafluoroethylene powder, place it inside the drying device after compaction, control the temperature of the drying device at 160-200°C, continue drying for 8-12 minutes, take it out after drying, cool it to room temperature and roll it into a roll. After rolling, protective measures need to be set on the outside to avoid scratches during storage or transportation, which will affect the quality of the aluminum foil.

[0021] The bonding of polytetrafluoroethylene (PTFE) powder and polyphenylene sulfide (PPS) primer not only relies on the bonding force between polyphenylene sulfide (PPS) and tetrafluoroethylene (PTFE) powder, but also adopts hot embedding technology.

[0022] The cleaning solution is NMP (N-methylpyrrolidone).

[0023] The polyphenylene sulfide is coated on the outside of the aluminum foil by roller coating or dipping.

[0024] The tetrafluoroethylene powder is coated on the outside of the aluminum foil by roller coating, dip coating or spray coating.

[0025] The specific method of the step 1 cleaning is to place the cleaning liquid into the pool, and soak the aluminum foil substrate in the cleaning liquid for 6-10 minutes.

[0026] In the step 2, it is necessary to carry out in a clean environment to prevent dust from accumulating on the surface of the aluminum foil substrate, thereby affecting the normal adhesion effect of the polytetrafluoroethylene (PTFE) powder and the polyphenylene sulfide (PPS) coating.

[0027] In the step 4, the method for compacting the tetrafluoroethylene powder coated on the surface of the aluminum foil is a molding method.

[0028] Embodiment 1: The composite coating of the super-hydrophobic aluminum foil is made of polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powder. The specific steps of its production process are as follows: Step 1: Select an aluminum foil substrate, prepare a cleaning solution, and heat the cleaning solution through a heating device until the temperature of the cleaning solution rises to 50° C. At this time, the cleaning solution is used to clean the grease on the surface of the aluminum foil substrate; Step 2: After the aluminum foil substrate is cleaned, place it in a ventilated place and drain the water, place the aluminum foil in a drying device, control the temperature of the drying device to 60°C, and continue drying for 6 minutes. After the aluminum foil is dried, coat the surface with polyphenylene sulfide, and the coating thickness is controlled to be 1um; Step 3: Place the aluminum foil coated with polyphenylene sulfide in the drying device, adjust the temperature of the drying device to 180°C, continue drying for 6 minutes, take it out after drying and continue coating with tetrafluoroethylene powder, and control the coating thickness to 1um; Step 4: compact the tetrafluoroethylene powder coated on the surface of the aluminum foil, place it in a drying device after compaction, control the temperature of the drying device at 160°C, continue drying for 8 minutes, take it out after drying, cool it to room temperature and roll it; Embodiment 2: The composite coating of the super-hydrophobic aluminum foil is made of polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powder. The specific steps of its production process are as follows: Step 1: Select an aluminum foil substrate, prepare a cleaning solution, and heat the cleaning solution by a heating device until the temperature of the cleaning solution rises to 55° C. At this time, the cleaning solution is used to clean the grease on the surface of the aluminum foil substrate; Step 2: After the aluminum foil substrate is cleaned, place it in a ventilated place and drain the water, place the aluminum foil in a drying device, control the temperature of the drying device to 70°C, and continue drying for 7 minutes. After the aluminum foil is dried, coat its surface with polyphenylene sulfide, and the coating thickness is controlled to be 1.5um; Step 3: Place the aluminum foil coated with polyphenylene sulfide in the drying device, adjust the temperature of the drying device to 230°C, continue drying for 8 minutes, take it out after drying and continue coating with tetrafluoroethylene powder, and control the coating thickness to 1.25um; Step 4: compact the tetrafluoroethylene powder coated on the surface of the aluminum foil, place it in a drying device after compaction, control the temperature of the drying device at 180°C, continue drying for 10 minutes, take it out after drying, cool it to room temperature and roll it; Embodiment 3: The composite coating of the super-hydrophobic aluminum foil is made of polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powder. The specific steps of its production process are as follows: Step 1: Select an aluminum foil substrate, prepare a cleaning solution, and heat the cleaning solution by a heating device until the temperature of the cleaning solution rises to 60° C. At this time, the cleaning solution is used to clean the grease on the surface of the aluminum foil substrate; Step 2: After the aluminum foil substrate is cleaned, place it in a ventilated place and drain the water, place the aluminum foil in a drying device, control the temperature of the drying device to 80°C, and continue drying for 8 minutes. After the aluminum foil is dried, coat the surface with polyphenylene sulfide, and the coating thickness is controlled to be 2um; Step 3: Place the aluminum foil coated with polyphenylene sulfide in the drying device, adjust the temperature of the drying device to 280°C, continue drying for 10 minutes, take it out after drying and continue coating with tetrafluoroethylene powder, and control the coating thickness to 1.5um; Step 4: Compact the tetrafluoroethylene powder coated on the surface of the aluminum foil, place it in a drying device after compaction, control the temperature of the drying device at 200°C, continue drying for 12 minutes, take it out after drying, cool it to room temperature and roll it up.

[0029] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing a composite coated super-hydrophobic aluminum foil, characterized in that: The composite coating of the super-hydrophobic aluminum foil is made of polyphenylene sulfide (PPS) and polytetrafluoroethylene (PTFE) powder. The specific steps of its production process are as follows: Step 1: Select an aluminum foil substrate, prepare a cleaning solution, heat the cleaning solution by a heating device until the temperature of the cleaning solution rises to 50-60°C, and then clean the surface of the aluminum foil substrate by the cleaning solution; Step 2: Dry the cleaned aluminum foil. After the aluminum foil substrate is cleaned, dry it at a temperature of 60-80°C for 6-8 minutes. After the aluminum foil is dried, coat the surface with polyphenylene sulfide. The coating thickness is controlled at 1-2um. Step 3: Place the aluminum foil coated with polyphenylene sulfide in the drying device, adjust the temperature of the drying device to 180-280°C, dry for 3-5 minutes to a semi-dry state, and then coat the aluminum foil with tetrafluoroethylene powder in this state, with the coating thickness controlled to 1-1.5um; Step 4: compact the aluminum foil coated with tetrafluoroethylene powder, place it in a drying device after compaction, control the temperature of the drying device at 160-200°C, continue drying for 8-12 minutes, take it out after drying, cool it to room temperature and roll it up.

2. The process for making a super-hydrophobic aluminum foil with a composite coating according to claim 1, characterized in that: The cleaning solution is NMP (N-methylpyrrolidone).

3. The process for making a super-hydrophobic aluminum foil with a composite coating according to claim 1, characterized in that: The polyphenylene sulfide is coated on the outside of the aluminum foil by roller coating or dipping.

4. The process for making a super-hydrophobic aluminum foil with a composite coating according to claim 1, characterized in that: The tetrafluoroethylene powder is coated on the outside of the aluminum foil by roller coating, dip coating or spray coating.

5. The process for making a super-hydrophobic aluminum foil with a composite coating according to claim 1, characterized in that: The specific method of the step 1 cleaning is to place the cleaning liquid into the pool, and soak the aluminum foil substrate in the cleaning liquid for 6-10 minutes.

6. The process for making a super-hydrophobic aluminum foil with a composite coating according to claim 1, characterized in that: In the step 4, the method for compacting the tetrafluoroethylene powder coated on the surface of the aluminum foil is a molding method.

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