Swelling-resistant polyphenylene sulfide coating with good toughness and application thereof

Abstract

The invention provides an anti-swelling polyphenylene sulfide coating with good toughness and application thereof, and particularly relates to the technical field of anticorrosive paint. Compared with a conventional polyphenylene sulfide coating, the polyphenylene sulfide coating has a proper and controllable crystallinity range, the crystallinity ranges from 12% to 35%, and the coating can pass 180-degree bending toughness testing of a shaft rod with the diameter ranging from 2 mm to 10 mm. After the coating is soaked in trichloromethane for 30 days at the normal temperature, the weight change rate of swelling weight increment is smaller than or equal to 9.5 wt.%, and after the coating is soaked in N-methyl pyrrolidone for 30 days at the normal temperature, the weight change rate of swelling weight increment is smaller than or equal to 3 wt.%. The coating is prepared from the following components in percentage by weight: 90 to 99.9 percent of polyphenylene sulfide powder and the balance of filler. The polyphenylene sulfide coating disclosed by the invention not only has excellent swelling resistance, but also has better toughness by controlling a proper crystallinity range.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, and in particular to a polyphenylene sulfide coating with good swelling resistance and toughness and its application. Background Technology

[0002] Corrosion is a common phenomenon across various industries, especially in the harsh environments of the chemical and petrochemical sectors, where the problem is even more severe. The economic losses caused by corrosion in industry are incalculable. Surface protection is an effective method for addressing equipment corrosion. Polyphenylene sulfide (PPS), as an anti-corrosion material, has been widely used abroad due to its excellent mechanical, thermodynamic, electrical, and chemical stability, and is considered a superior coating material for heavy-duty corrosion protection.

[0003] However, traditional PPS coatings suffer from insufficient resistance to solvent swelling and poor toughness, making them prone to cracking. Organic solvents cause the coating to swell, significantly reducing adhesion and leading to blistering. Low toughness also makes the coating susceptible to cracking during use, both of which greatly reduce its lifespan. Research on the solvent swelling resistance and toughness of PPS coatings is limited. Existing technologies produce PPS coatings in a metastable, amorphous aggregated state during heat treatment. Increased operating temperatures easily lead to secondary crystallization, generating internal stress, reducing the coating's adhesion to the substrate, and even causing embrittlement and cracking. Under high-temperature melting conditions, PPS coatings undergo cross-linking reactions with air. Existing technologies produce PPS coatings with excessively high cross-linking levels (below 10%), which, while significantly improving toughness, results in poor solvent swelling resistance. Conversely, excessively increasing the crystallinity leads to extremely poor toughness, making the coating prone to cracking and failure. Therefore, we need a PPS coating with optimal crystallinity that satisfies both improved swelling resistance and good toughness.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] One of the objectives of this invention is to provide a polyphenylene sulfide coating that addresses at least one of the aforementioned technical problems in the prior art.

[0006] The second objective of this invention is to provide an application of a polyphenylene sulfide coating.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a polyphenylene sulfide coating with good solvent resistance, swelling properties, and toughness, which is formed by melting a powder coating composed of polyphenylene sulfide powder and fillers. The polyphenylene sulfide powder accounts for 90~99.9 wt.%, with the remainder being filler.

[0008] Furthermore, the crystallinity of the coating is between 12% and 35%. The coating exhibits a swelling weight change rate ≤9.5 wt.% after immersion in chloroform at room temperature for 30 days, and a swelling weight change rate ≤3 wt.% after immersion in N-methylpyrrolidone at room temperature for 30 days.

[0009] Furthermore, the coating has a flexural toughness of 2-10 mm.

[0010] Furthermore, the powder coating melts on the surface of the object to form a coating, and the melting temperature T is 310-355℃.

[0011] Furthermore, the relationship between the melting time t (min) and the melting temperature T (°C) of the coating is: 800 / (T-295)≤(t+5)≤1800 / (T-295).

[0012] Furthermore, the filler is mica, wollastonite, silica, glass microspheres, silicon carbide, alumina, boron nitride, aluminum nitride, silicon nitride, titanium dioxide, iron oxide, kaolin, clay, talc, feldspar, barium sulfate, calcium sulfate, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, PTFE, PFA, FEP, ETFE, ECTFE, PVDF, PEEK, PAI, PI, PPSU, PSU, PES, etc.

[0013] The D50 particle size of the filler is 0.1-100μm, preferably 1-20μm.

[0014] Preferably, the polyphenylene sulfide powder has a melt index of 50~800g / 10min, and more preferably 100~400g / 10min.

[0015] And / or, the polyphenylene sulfide powder D50 has a particle size of 10~100μm, preferably 30~75μm.

[0016] A second aspect of the present invention provides the application of the polyphenylene sulfide coating on a metal substrate, the metal substrate including stainless steel, carbon steel, galvanized steel, iron, aluminum alloy, copper alloy or titanium alloy.

[0017] The third aspect of the present invention provides the application of the polyphenylene sulfide coating in the fields of corrosion protection, automotive, aerospace, electronics and electrical engineering, or home appliances.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: The polyphenylene sulfide (PPS) coating provided by this invention has a crystallinity of 12-35%. The crystalline regions in the PPS coating effectively prevent swelling and penetration of the medium, thus improving its anti-swelling properties. If the crystallinity is too low, the coating has poor anti-swelling properties; if the crystallinity is too high, it is prone to embrittlement and cracking, leading to coating failure. Therefore, it is necessary to prepare a PPS coating with a suitable crystallinity, giving it both excellent anti-swelling properties and good toughness. This improvement in overall performance makes the PPS powder coating of this invention have broader application prospects and higher practical value in various industrial anti-corrosion applications.

[0019] The application of the polyphenylene sulfide coating provided by this invention, given the advantages of the aforementioned polyphenylene sulfide coating, has brought significant technological progress and application advantages to the fields of chemical corrosion protection, automotive, aerospace, electronics and electrical engineering, and home appliances, improving product performance and reliability, reducing maintenance costs, and enhancing user experience. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. The components of the embodiments of this invention can be arranged and designed in various different configurations.

[0021] This invention provides a polyphenylene sulfide coating with good swelling resistance and toughness, which is formed by melting a powder coating composed of polyphenylene sulfide powder and fillers. The polyphenylene sulfide powder accounts for 90~99.9 wt.%, with the remainder being filler.

[0022] Typically, but not limitingly, the percentage of filler can be, for example, 0.1 wt.%, 1 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 9 wt.%, or any value in the range of 0.1 wt.% to 10 wt.%.

[0023] The polyphenylene sulfide (PPS) coating provided by this invention has a crystallinity of 12-35%. The crystalline regions in the PPS coating effectively prevent swelling and penetration of the medium, thus improving its anti-swelling properties. If the crystallinity is too low, the coating has poor anti-swelling properties; if the crystallinity is too high, it is prone to embrittlement and cracking, leading to coating failure. Therefore, it is necessary to prepare a PPS coating with a suitable crystallinity, giving it both excellent anti-swelling properties and good toughness. This improvement in overall performance makes the PPS powder coating of this invention have broader application prospects and higher practical value in various industrial anti-corrosion applications.

[0024] The crystallinity of the coating is between 12% and 35%; the swelling weight change rate of the coating after immersion in chloroform at room temperature for 30 days is ≤9.5wt.%, and the swelling weight change rate after immersion in N-methylpyrrolidone at room temperature for 30 days is ≤3wt.%.

[0025] With a preferred PPS coating crystallinity between 23% and 30%, the coating can pass a 180° bending toughness test using a shaft with a diameter of 4-8 mm. The weight change rate of the coating after immersion in chloroform at room temperature for 30 days is ≤5.5 wt.%, and the weight change rate after immersion in N-methylpyrrolidone at room temperature for 30 days is ≤1 wt.%.

[0026] Furthermore, the coating has a flexural toughness of 2-10 mm.

[0027] Furthermore, the powder coating melts on the surface of the object to form a coating, and the melting temperature T is 310-355℃.

[0028] Furthermore, the relationship between the melting time t (min) and the melting temperature T (°C) of the coating is: 800 / (T-295)≤(t+5)≤1800 / (T-295).

[0029] Furthermore, the filler is mica, wollastonite, silica, glass microspheres, silicon carbide, alumina, boron nitride, aluminum nitride, silicon nitride, titanium dioxide, iron oxide, kaolin, clay, talc, feldspar, barium sulfate, calcium sulfate, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, PTFE, PFA, FEP, ETFE, ECTFE, PVDF, PEEK, PAI, PI, PPSU, PSU, PES, etc.

[0030] The D50 particle size of the filler is 0.1-100μm, preferably 1-20μm.

[0031] Furthermore, the melt index of the polyphenylene sulfide powder is 50~800g / 10min, preferably 100~400g / 10min.

[0032] Typically, but not limitingly, the melt index of the polyphenylene sulfide powder may be, for example, 50 g / 10 min, 100 g / 10 min, 150 g / 10 min, 200 g / 10 min, 250 g / 10 min, 500 g / 10 min, 800 g / 10 min, or any value in the range of 50 to 800 g / 10 min.

[0033] Furthermore, the polyphenylene sulfide powder D50 has a particle size of 10~100μm, preferably 30~75μm.

[0034] Typically, but not limitingly, the D50 particle size of the polyphenylene sulfide powder can be, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm or 100 μm, or any value in the range of 10 to 100 μm.

[0035] The polyphenylene sulfide (PPS) powder coating provided by this invention contains 0.1~10 wt.% filler. The addition of filler promotes heterogeneous nucleation and crystallization of the PPS matrix, increasing the crystallinity of the coating. Increased crystallinity helps enhance the thermal stability and mechanical properties of the coating. Simultaneously, heterogeneous nucleation and crystallization can form layers of barriers within the material. This barrier effect, also known as the "shielding effect" and "maze effect," increases the complexity of the solvent permeation path, effectively reducing the solvent permeability of the coating and limiting the swelling of the PPS network, thereby improving the coating's anti-swelling performance. Furthermore, the filler helps the coating form a more uniform heterogeneous network, further limiting the swelling of PPS molecules.

[0036] The second aspect of the present invention provides the application of the polyphenylene sulfide coating on a metal substrate, the metal substrate including stainless steel, carbon steel, galvanized steel, iron, aluminum alloy, copper alloy or titanium alloy, etc.

[0037] The third aspect of the present invention provides the application of the polyphenylene sulfide coating in the fields of corrosion protection, automotive, aerospace, electronics and electrical engineering, or home appliances.

[0038] The application of the polyphenylene sulfide coating provided by this invention, given the advantages of the aforementioned polyphenylene sulfide coating, has brought significant technological progress and application advantages to the fields of chemical corrosion protection, automotive, aerospace, electronics and electrical engineering, and home appliances, improving product performance and reliability, reducing maintenance costs, and enhancing user experience.

[0039] The following detailed description of some embodiments of the present invention is provided in conjunction with examples. Unless otherwise specified, the following embodiments and features can be combined with each other. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples were all commercially available. The preparation processes in the following embodiments and comparative examples should be appropriately adjusted for different workpieces or application scenarios, with the final coating crystallinity as the determining factor.

[0040] Example 1 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Mix dry PPS powder (D50 of 35μm, melt index of 140g / 10min) with mica powder (D50 of 5μm) in a uniform weight ratio of 95 parts PPS to 5 parts mica to obtain PPS powder coating.

[0041] 2. Apply PPS powder coating to the surface of a 200*100*6mm 304 stainless steel sheet using electrostatic spraying until the entire surface is covered with powder. Place the sheet in a high-temperature oven at 280℃ and keep it at that temperature for about 30 minutes until the coating temperature reaches close to 280℃.

[0042] 3. Adjust the oven temperature to 340℃, and heat the oven to 340℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 340℃, keep it at that temperature for 30 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0043] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 340 μm.

[0044] Example 2 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0045] 2. Same as the steps in Example 1.

[0046] 3. Adjust the oven temperature to 340℃, and heat the oven to 340℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 340℃, keep it at that temperature for 20 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0047] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 362 μm.

[0048] Example 3 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0049] 2. Same as the steps in Example 1.

[0050] 3. Adjust the oven temperature to 340℃, and heat the oven to 340℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 340℃, keep it at that temperature for 13 minutes. After the temperature is maintained, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0051] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 332 μm.

[0052] Example 4 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0053] 2. Same as the steps in Example 1.

[0054] 3. Adjust the oven temperature to 320℃ and heat the oven to 320℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 320℃, keep it at that temperature for 60 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0055] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 316 μm.

[0056] Example 5 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0057] 2. Same as the steps in Example 1.

[0058] 3. Adjust the oven temperature to 320℃ and heat the oven to 320℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 320℃, keep it at that temperature for 35 minutes. After the temperature is maintained, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0059] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 335 μm.

[0060] Example 6 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0061] 2. Same as the steps in Example 1.

[0062] 3. Adjust the oven temperature to 320℃ and heat the oven to 320℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 320℃, keep it at that temperature for 25 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0063] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 344 μm.

[0064] Example 7 This embodiment provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0065] 2. Same as the steps in Example 1.

[0066] 3. Adjust the oven temperature to 320℃ and heat the oven to 320℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 320℃, keep it at that temperature for 15 minutes. After the temperature is maintained, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0067] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 350 μm.

[0068] Comparative Example 1 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0069] 2. Same as the steps in Example 1.

[0070] 3. Adjust the oven temperature to 365℃, and heat the oven to 365℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 365℃, keep it at that temperature for 50 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0071] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 321 μm.

[0072] Comparative Example 2 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0073] 2. Same as the steps in Example 1.

[0074] 3. Adjust the oven temperature to 350℃, and heat the oven to 350℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 350℃, keep it at that temperature for 40 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0075] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 337 μm.

[0076] Comparative Example 3 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0077] 2. Same as the steps in Example 1.

[0078] 3. Adjust the oven temperature to 340℃, and heat the oven to 340℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 340℃, keep it at that temperature for 8 minutes. After the temperature is maintained, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0079] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 345 μm.

[0080] Comparative Example 4 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0081] 2. Same as the steps in Example 1.

[0082] 3. Adjust the oven temperature to 310℃, and heat the oven to 310℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 310℃, keep it at that temperature for 150 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0083] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 352 μm.

[0084] Comparative Example 5 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0085] 2. Same as the steps in Example 1.

[0086] 3. Adjust the oven temperature to 310℃ and heat the oven to 310℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 310℃, keep it at that temperature for 35 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0087] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 328 μm.

[0088] Comparative Example 6 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0089] 2. Same as the steps in Example 1.

[0090] 3. Adjust the oven temperature to 330℃, and heat the oven to 330℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 330℃, keep it at that temperature for 65 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0091] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 357 μm.

[0092] Comparative Example 7 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0093] 2. Same as the steps in Example 1.

[0094] 3. Adjust the oven temperature to 330℃, and heat the oven to 330℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 330℃, keep it at that temperature for 13 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0095] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 328 μm.

[0096] Comparative Example 8 This comparative example provides a polyphenylene sulfide coating, the preparation process of which is as follows: 1. Same as the steps in Example 1.

[0097] 2. Same as the steps in Example 1.

[0098] 3. Adjust the oven temperature to 300℃ and heat the oven to 300℃ at an average heating rate of ≥2℃ / min. After the coating melts and the steel plate to be sprayed reaches 300℃, keep it at that temperature for 150 minutes. After the heat preservation is completed, quickly turn off the oven heating source and open the oven door to cool it down, or remove the stainless steel plate and continue spraying.

[0099] 4. Repeat steps 2 and 3 twice to obtain a polyphenylene sulfide coating. The coating thickness was measured to be 330 μm.

[0100] Test method: The coating samples prepared in the examples and comparative examples were subjected to testing. The testing items are as follows: Average heating rate; Average heating rate = (Final temperature - Initial temperature) / Heating time, unit °C / min; Melting time: The timer starts when the temperature of the polyphenylene sulfide coating reaches the set holding temperature of the oven and continues until the oven heating is turned off.

[0101] Crystallinity: Crystallinity was determined by DSC method, with a temperature range of 30~350℃, a heating rate of 5℃ / min, and a nitrogen atmosphere.

[0102] Swelling weight change rate: At room temperature, PPS coated samples were immersed in pure solvents of chloroform and N-methylpyrrolidone (NMP) for 30 days. The weight change of the coating was the difference between the weight after immersion and the weight before immersion. The swelling weight change rate was obtained by dividing the weight of the coating before immersion by the weight of the metal substrate.

[0103] Bending toughness: According to the national standard GB / T 6742-2007, the coating is tested using a paint film bending tester. After bending the coating 180° with a shaft bar with a diameter of 2~32mm, observe whether there is cracking or peeling. Test the smaller diameter shafts in sequence (from large to small) until the coating cracks or peels off from the base plate. Record the smallest shaft bar diameter at which the coating does not crack or peel off.

[0104] Melt flow index test: The melt flow index was tested using a GOTTFERT MI-2.2 melt flow rate meter with a load of 5KG.

[0105] Powder particle size D50 test: The test was conducted using a Microtrac S3500 laser particle size analyzer. Before the test, the powder was ultrasonically dispersed in ethanol for 5 minutes, with a refractive index of 1.77.

[0106] Coating thickness test: According to the national standard GB / T 13452.2-2008, a dry film thickness magnetic tester was used. After calibrating the instrument according to the manufacturer's instructions, 20 readings were taken evenly and the average value was taken.

[0107] The test results of the samples are shown in Table 1 below.

[0108] Table 1

[0109] As can be seen from Table 1, Comparative Example 5, compared to Example 1, has too high a degree of crystallinity, making it brittle and prone to cracking, resulting in extremely poor coating toughness; Comparative Example 1, compared to Example 1, has too low a degree of crystallinity, resulting in very poor resistance to swelling. Comparative Example 8 shows that although baking at around 300°C for a long time can achieve similar results, the baking time is too long, the processing efficiency is too low, the processing cost increases significantly, and it is not competitive.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyphenylene sulfide coating with good swelling resistance and toughness, characterized in that, The powder coating is formed by melting polyphenylene sulfide powder and filler, wherein the proportion of polyphenylene sulfide powder is 90~99.9 wt.% and the balance is filler.

2. The polyphenylene sulfide coating according to claim 1, characterized in that, The crystallinity of the coating is between 12% and 35%; the swelling weight change rate of the coating after immersion in chloroform at room temperature for 30 days is ≤9.5wt.%, and the swelling weight change rate after immersion in N-methylpyrrolidone at room temperature for 30 days is ≤3wt.%.

3. The polyphenylene sulfide coating according to claim 1, characterized in that, The coating has a flexural toughness of 2-10 mm.

4. The polyphenylene sulfide coating according to claim 1, characterized in that, The powder coating melts on the surface of the object to form a coating, and the melting temperature T is 310-355℃.

5. The polyphenylene sulfide coating according to claim 4, characterized in that, The relationship between the melting time t (min) and the melting temperature T (°C) of the powder coating is: 800 / (T-295)≤(t+5)≤1800 / (T-295).

6. The polyphenylene sulfide coating according to claim 1, characterized in that, The filler is at least one of mica, wollastonite, silica, glass microspheres, silicon carbide, alumina, boron nitride, aluminum nitride, silicon nitride, titanium dioxide, iron oxide, kaolin, clay, talc, feldspar, barium sulfate, calcium sulfate, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, PTFE, PFA, FEP, ETFE, ECTFE, PVDF, PEEK, PAI, PI, PPSU, PSU, and PES; the D50 particle size of the filler is 0.1-100 μm, preferably 1-20 μm.

7. The polyphenylene sulfide coating according to claim 1, characterized in that, The polyphenylene sulfide powder has a melt index of 50~800 g / 10 min, preferably 100~400 g / 10 min; And / or, the polyphenylene sulfide powder D50 has a particle size of 10~100μm, preferably 30~75μm.

8. The polyphenylene sulfide coating according to claim 1, characterized in that, The coating is heated at 280-290℃ for 30 minutes, and then heated to the melting temperature T at a heating rate of ≥2℃ / min.

9. The application of the polyphenylene sulfide coating according to any one of claims 1 to 8 on a metal substrate, characterized in that, The metal substrate includes stainless steel, carbon steel, galvanized steel, iron, aluminum, aluminum alloy, copper alloy, or titanium alloy.

10. The application of the polyphenylene sulfide coating according to any one of claims 1 to 8 in the fields of corrosion protection, automotive, aerospace, electronics and electrical engineering, or home appliances.

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