Modified polytetrafluoroethylene film layer and application thereof

Abstract

The invention relates to a modified polytetrafluoroethylene film layer and application thereof. The modified polytetrafluoroethylene film layer comprises a polytetrafluoroethylene matrix; the filler is dispersed in the polytetrafluoroethylene matrix, and the filler comprises inorganic matter particles. The modified polytetrafluoroethylene film layer provided by the invention has few additives and excellent corrosion resistance, and the cost can be saved while better corrosion resistance is realized.

Description

Technical Field

[0001] The present application relates to the field of exhaust gas treatment technology, specifically to a modified polytetrafluoroethylene film layer and its application, and more specifically to a modified polytetrafluoroethylene film layer, an EGR valve housing and its preparation method, an EGR valve, an exhaust gas treatment device, an engine and a vehicle. Background Art

[0002] The EGR valve is a mechatronic device installed on a vehicle to control the amount of exhaust gas recirculated back into the intake system. It is a crucial and critical component in the exhaust gas recirculation system. Its function is to control the amount of exhaust gas entering the intake manifold, allowing a certain amount of exhaust gas to flow into the intake manifold for recirculation. By directing exhaust gas from engine combustion into the intake manifold for combustion, it reduces combustion chamber temperature, improves engine efficiency, improves the combustion environment, reduces engine load, effectively reduces NOx emissions, reduces knock, and extends the service life of various components. However, in actual use, EGR valves are prone to corrosion, significantly reducing their service life. Therefore, current EGR valve technology still needs improvement. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present application proposes a modified polytetrafluoroethylene film layer with excellent corrosion resistance and its application.

[0004] In the first aspect of the present application, a modified polytetrafluoroethylene (PTFE) film layer is provided. According to an embodiment of the present application, the modified polytetrafluoroethylene film layer includes: a polytetrafluoroethylene matrix; a filler, wherein the filler is dispersed in the polytetrafluoroethylene matrix, and the filler includes inorganic particles. In the modified polytetrafluoroethylene film layer provided by the present application, the PTFE resin has excellent chemical inertness after film formation, does not undergo chemical reactions in most environments, and has good corrosion resistance. By adding inert fillers, the binding force between the macromolecular clusters of the PTFE resin can be improved, and the micropores that are prone to appear in the PTFE matrix can be filled, thereby greatly improving the covering power of the PTFE film layer, thereby effectively improving the corrosion resistance of the film layer. In summary, the modified polytetrafluoroethylene film layer provided by the present application has a small number of additives, has excellent corrosion resistance, and can save costs while achieving better corrosion resistance.

[0005] According to an embodiment of the present application, the inorganic particles include at least one of aluminum oxide particles, glass fiber particles, titanium powder, and ceramic particles, thereby achieving better corrosion resistance and lowering the cost.

[0006] According to an embodiment of the present application, the filler includes spherical particles and non-spherical particles. The addition of spherical particles helps to enhance the bonding strength between PTFE resin macromolecular clusters, while the addition of non-spherical particles helps to fill the micropores that are prone to appearing in the PTFE matrix, thereby making the modified polytetrafluoroethylene film layer more uniform and essentially free of through holes. When the film layer is applied to the surface of an object, it can better cover the surface of the object, thereby achieving better corrosion resistance.

[0007] According to an embodiment of the present application, the mass ratio of the spherical particles to the non-spherical particles is 0.5-1.5:0.5-1.5, and specifically 0.8-1.2:0.8-1.2. Within this ratio range, the modified polytetrafluoroethylene film layer can balance the bonding strength between the PTFE resin macromolecular clusters and the micropore filling effect in the film layer, resulting in a film layer with better corrosion resistance.

[0008] According to an embodiment of the present application, the particle size of the spherical aluminum oxide particles is 5 μm to 20 μm; and / or the particle size of the non-spherical aluminum oxide particles is 5 μm to 20 μm.

[0009] According to an embodiment of the present application, the mass ratio of the polytetrafluoroethylene matrix to the filler is 30 to 40:4 to 6. Within the above ratio range, the modified polytetrafluoroethylene film layer has stronger covering power and better anti-corrosion performance.

[0010] According to an embodiment of the present application, the modified polytetrafluoroethylene film layer may further include a colorant to adjust the color of the finished film layer as needed. In some embodiments, the colorant may include carbon black.

[0011] According to the embodiments of the present application, the thickness of the modified polytetrafluoroethylene film layer can be 20 μm to 60 μm. Within the above thickness range, it can meet the requirements of most usage scenarios and exert excellent anti-corrosion effect.

[0012] In a second aspect, this application provides an EGR valve housing. According to an embodiment of the present application, the modified polytetrafluoroethylene film layer described above is provided on at least a portion of the inner surface of the EGR valve housing. It will be appreciated that, during actual use, the EGR valve primarily passes through its interior through exhaust gas. By providing the modified polytetrafluoroethylene film layer on the inner surface, exhaust gas corrosion on the inner surface of the EGR valve housing can be effectively mitigated, thereby extending the service life of the EGR valve housing.

[0013] The third aspect of the present application provides a method for preparing the EGR valve housing described above. According to an embodiment of the present application, the method includes: mixing a polytetrafluoroethylene dispersion resin, a filler, and an organic solvent according to a predetermined weight ratio to obtain a raw material mixture; cleaning at least a portion of the inner surface of the EGR valve housing body to obtain a clean EGR valve housing body; preheating the clean EGR valve housing body to obtain a preheated EGR valve housing body; spraying the raw material mixture on at least a portion of the inner surface of the EGR valve housing body to form a raw material coating; and drying the EGR valve housing body with the raw material coating to obtain the EGR valve housing. Through the above method, a modified polytetrafluoroethylene film layer with excellent corrosion resistance and strong bonding with the inner surface of the EGR valve housing body can be obtained on the inner surface of the EGR valve housing body, thereby obtaining an EGR valve housing with better performance and longer service life; and the method is simple to operate, convenient, and easy to mass produce.

[0014] According to an embodiment of the present application, the longest axis length of the polytetrafluoroethylene dispersed resin particles is no more than 40 μm.

[0015] According to an embodiment of the present application, the organic solvent includes at least one of N-methyl-2-pyrrolidone, methyl isobutyl ketone, light aromatic hydrocarbon solvent naphtha, 1,2,4-trimethylbenzene, and ethylbenzene.

[0016] According to an embodiment of the present application, the cleaning process includes the following steps performed in sequence:

[0017] Steam cleaning the inner surface of the EGR valve housing until the surface particle contaminant content is less than 5 mg and the longest axis of the particle contaminant does not exceed 5 μm;

[0018] Degreasing and cleaning the inner surface of the EGR valve housing;

[0019] The inner surface of the EGR valve housing body is sandblasted.

[0020] According to an embodiment of the present application, the temperature of the preheating treatment is 140°C to 160°C.

[0021] According to the embodiment of the present application, the spraying amount of the raw material mixture is 100g / m 2 ~148g / m 2 .

[0022] According to an embodiment of the present application, the raw material coating is formed by multiple spraying processes, and the thickness of the film formed by a single spraying process is no more than 35 μm, specifically, can be 25 μm to 35 μm.

[0023] According to an embodiment of the present application, the drying temperature is 240° C. to 260° C., and the drying time is 20 minutes to 60 minutes.

[0024] In a fourth aspect, the present application provides an EGR valve. According to an embodiment of the present application, the EGR valve includes the aforementioned EGR valve housing or an EGR valve housing prepared by the aforementioned method. The EGR valve has all the features and advantages of the aforementioned EGR valve housing, which will not be further elaborated here.

[0025] In a fifth aspect, the present application provides an exhaust gas treatment device. According to an embodiment of the present application, the exhaust gas treatment device includes the aforementioned EGR valve. As a result, the exhaust gas treatment device has a longer service life and a lower failure rate of the EGR valve.

[0026] In a sixth aspect, the present application provides an engine. According to an embodiment of the present application, the engine includes the exhaust gas treatment device described above. The engine has a longer EGR valve service life and a lower EGR valve maintenance rate.

[0027] In a seventh aspect, the present application provides a vehicle. According to an embodiment of the present application, the vehicle includes the aforementioned engine. The vehicle has all the features and advantages of the aforementioned engine, which will not be further elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic cross-sectional structure diagram of an EGR valve housing according to an embodiment of the present application.

[0029] Figure 2 It is a flow chart of a method for preparing an EGR valve housing according to an embodiment of the present application.

[0030] Figure 3 This is a sagittal cross-sectional photograph of the modified PTFE membrane layer obtained in Example 1 of the present application.

[0031] Figure 4 This is a sagittal cross-sectional photograph of the modified PTFE membrane layer obtained in Example 7 of the present application.

[0032] Figure 5 This is a sagittal cross-sectional photograph of the modified PTFE membrane layer obtained in Example 8 of the present application.

[0033] Figure 6 This is a sagittal cross-sectional photograph of the modified PTFE membrane layer obtained in Comparative Example 1 of the present application.

[0034] Figure 7 This is a photo of the EGR valve housing obtained in Example 1 of the present application before anti-corrosion testing.

[0035] Figure 8This is a photo of the EGR valve housing obtained in Example 1 of the present application after corrosion protection testing.

[0036] Figure 9 This is a photo of the EGR valve housing obtained in Example 9 of the present application before anti-corrosion testing.

[0037] Figure 10 This is a photo of the EGR valve housing obtained in Example 9 of the present application after anti-corrosion testing.

[0038] Figure 11 This is a photo of the EGR valve housing obtained in Comparative Example 2 of the present application after corrosion protection testing.

[0039] Figure 12 This is a photo of the EGR valve housing obtained in Comparative Example 3 of the present application after corrosion protection testing.

[0040] Figure 13 This is a photo of the EGR valve housing obtained in Comparative Example 4 of the present application after corrosion protection testing. DETAILED DESCRIPTION

[0041] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0042] In the first aspect of the present application, a modified polytetrafluoroethylene (PTFE) film layer is provided. According to an embodiment of the present application, the modified polytetrafluoroethylene film layer includes: a polytetrafluoroethylene matrix; a filler, wherein the filler is dispersed in the polytetrafluoroethylene matrix, and the filler includes inorganic particles. In the modified polytetrafluoroethylene film layer provided by the present application, the PTFE resin has excellent chemical inertness after film formation, does not undergo chemical reactions in most environments, and has good corrosion resistance. By adding inert fillers, the binding force between the macromolecular clusters of the PTFE resin can be improved, and the micropores that are prone to appear in the PTFE matrix can be filled, thereby greatly improving the covering power of the PTFE film layer, thereby effectively improving the corrosion resistance of the film layer. In summary, the modified polytetrafluoroethylene film layer provided by the present application has a small number of additives, has excellent corrosion resistance, and can save costs while achieving better corrosion resistance.

[0043] According to an embodiment of the present application, the inorganic particles include at least one of aluminum oxide particles, glass fiber particles, titanium powder, and ceramic particles. As a result, the modified polytetrafluoroethylene (PTFE) film layer has better corrosion resistance and lower cost.

[0044] According to an embodiment of the present application, the filler includes spherical particles and non-spherical particles. Specifically, the unmodified polytetrafluoroethylene film layer is not a uniform film layer, but rather is formed by multiple interconnected PTFE resin macromolecular clusters. The addition of spherical particles helps to enhance the binding force between the PTFE resin macromolecular clusters, while the addition of non-spherical particles helps to fill the micropores that are prone to appear in the PTFE matrix, thereby making the modified polytetrafluoroethylene film layer more uniform and essentially free of through holes. When the film layer is applied to the surface of an object, it can better cover the surface of the object, thereby achieving better corrosion resistance.

[0045] It can be understood that spherical particles refer to particles with a spherical or nearly spherical shape, while non-spherical particles are particles other than spherical particles, specifically particles with edges and corners, including but not limited to flakes, rods, tubes, polyhedrons, and other particles with poor sphericity.

[0046] According to an embodiment of the present application, the mass ratio of the spherical particles to the non-spherical particles is 0.5-1.5:0.5-1.5, specifically 0.8-1.2:0.8-1.2, and more specifically 0.5:0.5, 0.5:0.8, 0.5:1, 0.5:1.2, 0.5:1.5, etc. Within the above ratio range, the modified polytetrafluoroethylene film layer can take into account both the bonding strength between the PTFE resin macromolecular groups and the micropore filling effect in the film layer, thereby obtaining a film layer with better corrosion resistance.

[0047] According to an embodiment of the present application, the particle size of the spherical particles is 5 μm to 20 μm (specifically, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.). In some embodiments, the particle size of the non-spherical particles is 5 μm to 20 μm (specifically, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.). Within the above-mentioned particle size range, a good balance is achieved in breaking the PTFE chains, attracting the PTFE to wrap and form local aggregations, and using fillers to fill the gaps between the PTFE "chain balls", which is conducive to obtaining a film layer with excellent anti-corrosion performance.

[0048] Herein, the particle size of a filler particle refers to the maximum distance between any two points on the particle outline.

[0049] According to an embodiment of the present application, the mass ratio of the polytetrafluoroethylene matrix to the filler is 30-40:4-6, specifically 30:4, 30:5, 30:6, 35:4, 35:5, 35:6, 40:4, 40:5, 40:6, etc. Within the above ratio range, the modified polytetrafluoroethylene film layer has stronger hiding power and better corrosion resistance.

[0050] According to embodiments of the present application, the color of the modified polytetrafluoroethylene film layer may be required based on the actual use environment. In this case, the modified polytetrafluoroethylene film layer may further include a colorant to adjust the color of the finished film layer as needed. In some embodiments, the colorant may include carbon black.

[0051] According to the embodiments of the present application, the amount of the dye used is not particularly limited and can be flexibly selected according to the color to be achieved, as long as the target color is achieved.

[0052] According to the embodiments of this application, the thickness of the modified polytetrafluoroethylene film layer can be flexibly selected according to different usage environments and is not particularly limited in this application. In some embodiments, the thickness of the modified polytetrafluoroethylene film layer can be 20μm to 60μm, specifically 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, etc. Within this thickness range, it can meet the requirements of most usage scenarios and provide excellent corrosion protection.

[0053] In a second aspect, this application provides an EGR valve housing. According to an embodiment of the present application, the modified polytetrafluoroethylene film layer described above is provided on at least a portion of the inner surface of the EGR valve housing. It will be appreciated that, during actual use, the EGR valve primarily passes through its interior through exhaust gas. By providing the modified polytetrafluoroethylene film layer on the inner surface, exhaust gas corrosion on the inner surface of the EGR valve housing can be effectively mitigated, thereby extending the service life of the EGR valve housing. Figure 1 A schematic cross-sectional structure diagram of the EGR valve housing 10 is shown.

[0054] It can be understood that the modified polytetrafluoroethylene film layer can be provided on a portion of the inner surface of the EGR valve housing, or the entire inner surface of the EGR valve housing can be provided with the modified polytetrafluoroethylene film layer. The specific selection and adjustment can be flexibly made according to actual use needs and economic benefits.

[0055] In a third aspect of the present application, a method for preparing the aforementioned EGR valve housing is provided. Figure 2 , the method comprising:

[0056] S1: Mixing polytetrafluoroethylene dispersed resin particles, fillers, and an organic solvent to obtain a raw material mixture.

[0057] According to the embodiments of the present application, the specific method for mixing the raw materials is not particularly limited and can be flexibly selected according to actual needs. In some embodiments, the polytetrafluoroethylene dispersed resin particles, filler, and organic solvent can be placed in a rotating stirring mixing container and mixed. As an example, the mixing can be carried out at a stirring speed of 3000 r / min under normal temperature and humidity conditions for a mixing time of not less than 5 minutes to obtain a raw material mixture.

[0058] According to the embodiments of the present application, the longest axis length of the polytetrafluoroethylene dispersed resin particles is no greater than 40 μm, and specifically, 40 μm, 35 μm, 30 μm, 25 μm, 20 μm, 15 μm, 10 μm, etc. Within this size range, the energy consumption required for structural reconstruction can be reduced. Specifically, the amount of spraying raw materials required for film coating is reduced, the sintering temperature does not need to be too high, and the thickness of the single film layer can be controlled at a higher level. This can achieve excellent corrosion resistance while reducing mass production costs.

[0059] Herein, the polytetrafluoroethylene dispersed resin particles refer to powdered polytetrafluoroethylene resin. The longest axis length of the polytetrafluoroethylene dispersed resin particles refers to the maximum distance between any two points on the contour line of the polytetrafluoroethylene dispersed resin particles.

[0060] According to an embodiment of the present application, the organic solvent includes at least one of N-methyl-2-pyrrolidone, methyl isobutyl ketone, a light aromatic hydrocarbon solvent naphtha, 1,2,4-trimethylbenzene, and ethylbenzene. This allows for better dispersion of the tetrafluoroethylene dispersion resin, filler, and colorant, facilitating subsequent spraying steps to produce a high-quality film layer.

[0061] In this step, a dye may or may not be added to the raw material mixture, depending on the film color requirements. For example, the dye may be carbon black, and the specific amount of the dye may be adjusted according to the film color requirements, and is not particularly limited in this application.

[0062] S2: Clean at least a portion of the inner surface of the EGR valve housing body to obtain a clean EGR valve housing body.

[0063] Through cleaning treatment, pollutants and oxide layers on the inner surface of the EGR valve housing can be removed, the bonding strength between the inner surface of the EGR valve housing and the modified polytetrafluoroethylene film layer can be improved, and the erosion and peeling of the modified polytetrafluoroethylene film layer caused by the EGR exhaust environment can be effectively reduced.

[0064] According to an embodiment of the present application, the cleaning process may include the following steps performed in sequence:

[0065] S21: Steam cleaning the inner surface of the EGR valve housing body until the surface particulate matter content is less than 5 mg and the longest axis of the particulate matter does not exceed 5 μm;

[0066] S22: Degreasing and cleaning the inner surface of the EGR valve housing;

[0067] S23: performing sandblasting on the inner surface of the EGR valve housing body.

[0068] In this article, the detection methods for surface particle pollutant content and the longest axis of particle pollution can refer to the national standard GB / T3821-2015 Cleanliness Determination Method for Small and Medium-Power Internal Combustion Engines. However, the pollutant content and longest axis requirements need to be implemented in accordance with the standards provided in this article, that is, the surface particle pollutant content is less than 5 mg, and the longest axis of the particle pollutant does not exceed 5 μm.

[0069] In some embodiments, the degreasing cleaning may be performed by using a common degreasing solution in the industry for heat preservation cleaning, which is not particularly limited in this application. This step can effectively remove contaminants adhering to the inner surface of the EGR valve housing.

[0070] In some embodiments, the sandblasting process may be performed using a closed sandblasting machine. The sandblasting time may be controlled within 3 minutes, and the grit size may be 120 mesh, and specifically may not be less than 100 mesh. This can effectively remove the oxide layer on the inner surface of the EGR valve housing.

[0071] S3: preheating the clean EGR valve housing body to obtain a preheated EGR valve housing body.

[0072] Specifically, there is no particular limitation on the specific method of preheating the EGR valve housing body. For example, the EGR valve housing body can be placed in an oven. Preheating can facilitate the adhesion of the film coating and reduce raw material consumption.

[0073] According to an embodiment of the present application, the temperature of the preheating treatment is 140° C. to 160° C., specifically 140° C., 150° C., 160° C., etc. This can further facilitate the adhesion of the film coating and reduce raw material consumption.

[0074] In some specific embodiments, the temperature of the preheated EGR valve housing body can be controlled to be approximately 150±5° C., and the specific heating method is not particularly limited.

[0075] S4: spraying the raw material mixture onto at least a portion of the inner surface of the EGR valve housing body to form a raw material coating.

[0076] In this step, the spraying equipment can be adjusted as needed. The sprayed PTFE film layer raw material mixture should be well atomized, and the surface of the part can be coated with a uniform and flat PTFE film layer raw material.

[0077] Specifically, the preheated EGR valve housing body can be placed in a PTFE spraying device, and the PTFE film layer raw material can be sprayed on the EGR valve housing body according to technical requirements.

[0078] It can be understood that, depending on the thickness of the modified polytetrafluoroethylene film layer, the modified polytetrafluoroethylene film layer can be formed by spraying once or by spraying multiple times.

[0079] According to an embodiment of the present application, the thickness of the film formed by a single spraying is no greater than 35 μm, and can be 25 μm to 35 μm, specifically 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, etc. Thus, a modified polytetrafluoroethylene film layer with better quality and better corrosion resistance can be obtained.

[0080] According to the embodiment of the present application, the spraying amount of the raw material mixture is 100g / m 2 ~148g / m 2 (Specifically, 100g / m 2 , 105g / m 2 , 110g / m 2 , 115g / m 2 , 120g / m 2 , 125g / m 2 , 130g / m 2 , 135g / m 2 , 140g / m 2 , 145g / m 2 , 148g / m 2 Thus, it is suitable for forming a single layer of film with appropriate thickness. If the spraying amount is too much, it will cause a waste of raw materials. If the spraying amount is too little, it may affect the use effect.

[0081] In this article, the spray amount of the raw material mixture refers to the recommended spray amount required to form the thickest single layer film.

[0082] S5: Drying the EGR valve housing body formed with the raw material coating to obtain the EGR valve housing.

[0083] In this step, the organic solvent is evaporated to obtain a dried modified polytetrafluoroethylene film layer.

[0084] According to an embodiment of the present application, the drying temperature is 240°C to 260°C (specifically 240°C, 245°C, 250°C, 255°C, 260°C, etc.), and the drying time is 20 minutes to 60 minutes (specifically 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc.).

[0085] Through the above method, a modified polytetrafluoroethylene film layer with excellent corrosion resistance and strong bonding with the inner surface of the EGR valve housing body can be obtained on the inner surface of the EGR valve housing body, thereby obtaining an EGR valve housing with better performance and longer service life; and the method is simple and convenient to operate and easy to mass produce.

[0086] In a fourth aspect, the present application provides an EGR valve. According to an embodiment of the present application, the EGR valve includes the aforementioned EGR valve housing or an EGR valve housing prepared by the aforementioned method. The EGR valve has all the features and advantages of the aforementioned EGR valve housing, which will not be further elaborated here.

[0087] It will be understood that the EGR valve according to the embodiments of the present application can be a mechanical EGR valve or an electronically controlled EGR valve. Specifically, although the two types of EGR valves have different names, their core functions are similar: they are both designed to regulate the engine combustion chamber temperature, optimize power output, and enhance exhaust emissions by introducing combustion exhaust gas into the intake manifold, thereby extending the service life of engine components. Mechanical EGR valves use a piston or diaphragm to control the flow of exhaust gas, while electronically controlled EGR valves use an electronic control unit (ECU) to precisely control the amount of exhaust gas recirculated.

[0088] It can be understood that in addition to the EGR valve housing described above, the EGR valve according to the embodiment of the present application may also include other structures and components necessary for a conventional EGR valve. For details, please refer to conventional technology and will not be described in detail here.

[0089] In a fifth aspect, the present application provides an exhaust gas treatment device. According to an embodiment of the present application, the exhaust gas treatment device includes the aforementioned EGR valve. As a result, the exhaust gas treatment device has a longer service life and a lower failure rate of the EGR valve.

[0090] It can be understood that, in addition to the EGR valve described above, the exhaust gas treatment device also includes necessary structures and components of a conventional exhaust gas treatment device. For details, please refer to conventional technology and will not be described in detail here.

[0091] In a sixth aspect, the present application provides an engine. According to an embodiment of the present application, the engine includes the exhaust gas treatment device described above. The engine has a longer EGR valve service life and a lower EGR valve maintenance rate.

[0092] In a seventh aspect, the present application provides a vehicle. According to an embodiment of the present application, the vehicle includes the exhaust gas treatment device described above. The vehicle has all the features and advantages of the exhaust gas treatment device described above, which will not be further elaborated here.

[0093] According to the embodiments of the present application, the specific type of the vehicle is not particularly limited, and includes, but is not limited to, diesel vehicles, gasoline vehicles, hybrid vehicles, etc. It is understood that in addition to the exhaust gas treatment device described above, the vehicle may also include the necessary structures and components of a conventional vehicle, which may include a body, chassis, tires, seats, windows, engine, etc.

[0094] The embodiments of the present application are described in detail below.

[0095] Example 1

[0096] Step 1: Put polytetrafluoroethylene dispersion resin (with the longest axis length of 40 μm), alumina powder (spherical alumina (particle size of 10 μm) and non-spherical alumina (flake, particle size of 20 μm) in a mass ratio of 1:1), and organic solvent (a mixture of light aromatic hydrocarbon solvent naphtha and 1,2,4-trimethylbenzene in a mass ratio of 1:1) into a rotating stirring mixing container in a mass ratio of 8:1:11, and mix them at a stirring speed of 3000 r / min under normal temperature and humidity environment for 5 minutes to prepare a PTFE membrane layer raw material.

[0097] Step 2: Activate the EGR valve housing surface. Specifically, use an evaporative cleaning machine to clean all inner surfaces of the EGR valve housing until the particle count is less than 5mg and the longest axis length of the particles does not exceed 5μm. Degrease the inner surface of the EGR valve housing with a cleaning agent to remove adhering contaminants. Then, sandblast all inner surfaces of the EGR valve housing to ensure that the surface oxide layer is removed.

[0098] Step 3: Heat the EGR valve housing to 150°C and keep it warm.

[0099] Step 4: Take out the EGR valve housing kept at 150°C and put it into PTFE spraying equipment (air Teflon sprayer), and use the PTFE film layer raw material prepared above to spray it, with a single spraying thickness of 30 microns.

[0100] Step 5: Place the EGR valve housing that has been sprayed with PTFE film raw materials in a drying oven and heat it at 240°C for 40 minutes. After drying, conduct a surface PTFE film quality inspection to ensure that the film is free of bubbles, defects (automatically identified by a CCD industrial camera), local thickness that is too thin or too thick, and other defects (randomly inspected using a film thickness meter). When there are requirements for color, visual observation is also required to confirm the color uniformity of the film.

[0101] Step 6: Repeat the above steps 4 and 5, i.e., spray twice, and obtain a sagittal cross-sectional photo of the modified PTFE film layer (i.e., an optical microscope photo of the cross section of the modified PTFE film layer). Figure 3 .

[0102] Example 2

[0103] The same as Example 1, except that the mass ratio of the spherical alumina particles to the non-spherical alumina particles in the alumina powder is 0.5:1.5.

[0104] Example 3

[0105] The same as Example 1, except that the mass ratio of spherical alumina particles to non-spherical alumina particles in the alumina powder is 0.8:1.2.

[0106] Example 4

[0107] The same as Example 1, except that the mass ratio of spherical alumina particles to non-spherical alumina particles in the alumina powder is 1.2:0.8.

[0108] Example 5

[0109] The same as Example 1, except that the mass ratio of spherical alumina particles to non-spherical alumina particles in the alumina powder is 1.5:0.8.

[0110] Example 6

[0111] The same as Example 1, except that the mass ratio of spherical alumina particles to non-spherical alumina particles in the alumina powder is 1.5:0.5.

[0112] Example 7

[0113] Same as Example 1, except that the alumina powder consists only of spherical alumina particles. The obtained modified PTFE membrane layer is shown in the following figure. Figure 4 .

[0114] Example 8

[0115] Same as Example 1, except that the alumina powder consists only of non-spherical alumina particles. The obtained modified PTFE membrane layer is shown in the following figure: Figure 5 .

[0116] Example 9

[0117] Same as Example 1, except that: one spraying is performed to obtain a modified PTFE film layer with a thickness of 30 μm.

[0118] Example 10

[0119] Same as Example 1, except that the alumina particles are replaced with titanium powder.

[0120] Comparative Example 1

[0121] Same as Example 1, except that: an unmodified polytetrafluoroethylene film layer is formed on the inner surface of the EGR valve housing body. The obtained PTFE film layer is shown in the cross-sectional photograph. Figure 6 .

[0122] Comparative Example 2

[0123] Same as Example 1, except that a commercially available PTFE coating product (DuPont 958G) is used with a film thickness of 20 μm.

[0124] Comparative Example 3

[0125] Same as Example 1, except that a commercially available PTFE coating product (DuPont 958G) is used, and the film thickness is 40 μm.

[0126] Comparative Example 4

[0127] Same as Example 1, except that a commercially available PTFE coating product (DuPont 958G) is used, and the film thickness is 60 μm.

[0128] Performance testing:

[0129] 1. Anti-corrosion performance test: refer to the acid salt spray test method in GB / T 10125-2021 artificial atmosphere corrosion test for anti-corrosion performance test.

[0130] 2. Cross-cut test: Refer to the cross-cut test in GB / T 9286-2021 to evaluate the adhesion of the modified PTFE film layer.

[0131] The photos of the EGR valve housing obtained in Example 1 before and after the corrosion test are shown in Figure 1. Figure 7 and Figure 8 As can be seen from the figure, there is no corrosion spot on the film, the film adheres well, and the film does not fall off at all in the cross-cut test.

[0132] The photos of the EGR valve housing obtained in Example 9 before and after the anti-corrosion test are shown in Figure 1. Figure 9 and Figure 10 As can be seen from the figure, there is no obvious corrosion spot on the surface of the film, and there is slight peeling in the cross-cut test of the film.

[0133] The photo of the EGR valve housing obtained in comparative example 2 after corrosion testing is shown in Figure 11 Comparative Example 3 shows the photos of the EGR valve housing obtained after corrosion testing. Figure 12 Comparative Example 4 shows the photos of the EGR valve housing obtained after corrosion testing. Figure 13 As can be seen from the figure, obvious corrosion spots appear on the surface of the film.

[0134] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0135] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0136] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0137] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0138] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A modified polytetrafluoroethylene film layer, characterized in that: include: Polytetrafluoroethylene matrix; The filler is dispersed in the polytetrafluoroethylene matrix and comprises inorganic particles.

2. The modified polytetrafluoroethylene film layer according to claim 1, characterized in that: The inorganic particles include at least one of aluminum oxide particles, glass fiber particles, titanium powder, and ceramic particles.

3. The modified polytetrafluoroethylene film layer according to claim 1, characterized in that: The inorganic particles include spherical particles and non-spherical particles.

4. The modified polytetrafluoroethylene film layer according to claim 3, characterized in that: The mass ratio of the spherical particles to the non-spherical particles is 0.5-1.5:0.5-1.

5.

5. The modified polytetrafluoroethylene film layer according to claim 4, characterized in that: The mass ratio of the spherical particles to the non-spherical particles is 0.8-1.2:0.8-1.

2.

6. The modified polytetrafluoroethylene film layer according to claim 3, characterized in that: The particle size of the spherical particles is 5 μm to 20 μm; and / or The particle size of the non-spherical particles is 5 μm to 20 μm.

7. The modified polytetrafluoroethylene film layer according to claim 1, characterized in that: The mass ratio of the polytetrafluoroethylene matrix to the filler is 30-40:4-6.

8. The modified polytetrafluoroethylene film layer according to claim 1, characterized in that: Also includes stains.

9. The modified polytetrafluoroethylene film layer according to claim 8, characterized in that: The colorant includes carbon black.

10. The modified polytetrafluoroethylene film layer according to claim 1, characterized in that: The thickness of the modified polytetrafluoroethylene film layer is 20 μm to 60 μm.

11. An EGR valve housing, characterized in that: The modified polytetrafluoroethylene film layer according to any one of claims 1 to 10 is provided on at least a portion of the inner surface of the EGR valve housing.

12. A method for preparing the EGR valve housing according to claim 11, characterized in that: include: Mixing polytetrafluoroethylene dispersed resin particles, filler, and organic solvent according to a predetermined weight ratio to obtain a raw material mixture; Cleaning at least a portion of the inner surface of the EGR valve housing to obtain a clean EGR valve housing; performing a preheating treatment on the clean EGR valve housing body to obtain a preheated EGR valve housing body; spraying the raw material mixture on at least a portion of the inner surface of the EGR valve housing body to form a raw material coating; The EGR valve housing body formed with the raw material coating is dried to obtain the EGR valve housing.

13. The method according to claim 12, characterized in that The longest axis length of the polytetrafluoroethylene dispersed resin particles is no more than 40 μm.

14. The method according to claim 12, characterized in that The organic solvent includes at least one of N-methyl-2-pyrrolidone, methyl isobutyl ketone, light aromatic hydrocarbon solvent naphtha, 1,2,4-trimethylbenzene, and ethylbenzene.

15. The method according to claim 12, characterized in that The cleaning process includes the following steps performed in sequence: Steam cleaning the inner surface of the EGR valve housing until the surface particle contaminant content is less than 5 mg and the longest axis of the particle contaminant does not exceed 5 μm; Degreasing and cleaning the inner surface of the EGR valve housing; The inner surface of the EGR valve housing body is sandblasted.

16. The method according to claim 12, characterized in that The temperature of the preheating treatment is 140°C to 160°C.

17. The method according to claim 12, wherein: The spraying amount of the raw material mixture is 100g / m 2 ~148g / m 2 .

18. The method according to claim 12, characterized in that The raw material coating is formed by multiple spraying processes, and the thickness of the film formed by a single spraying process is no greater than 35 μm.

19. The method according to claim 18, characterized in that The thickness of the film formed by a single spraying is 25 μm to 35 μm.

20. The method according to claim 12, wherein The drying temperature is 240° C. to 260° C., and the drying time is 20 minutes to 60 minutes.

21. An EGR valve, characterized in that: The invention comprises the EGR valve housing according to claim 11 or the EGR valve housing prepared by the method according to any one of claims 12 to 20.

22. An exhaust gas treatment device, characterized in that: Including the EGR valve as claimed in claim 21.

23. An engine, characterized in that: Including the exhaust gas treatment device according to claim 22.

24. A vehicle, characterized in that: Including the engine described in claim 23.

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