Heat-resistant oxidized polyphenylene sulfide composite filter material and preparation method and application thereof

Abstract

The application discloses a kind of heat-resistant oxidized polyphenyl sulfide composite filter material and its preparation method and application, it is related to industrial dust filter material technical field.The preparation method of heat-resistant oxidized polyphenyl sulfide composite filter material of the present application: polyphenyl sulfide resin and antioxidant modified nanosilica are added into double screw extruder and are obtained after melting, mixing, dispersion, extrusion, pelletizing, spinning modified polyphenyl sulfide fiber;The modified polyphenyl sulfide fiber is needled on base cloth, and composite polyphenyl sulfide filter material is obtained;The composite polyphenyl sulfide filter material is added into modified polytetrafluoroethylene finishing liquid, and is obtained after dipping, calendering and baking heat-resistant oxidized polyphenyl sulfide composite filter material;Wherein, the antioxidant modified nanosilica is nanosilica loaded antioxidant 3114, and antioxidant 168 is included in the modified polytetrafluoroethylene finishing liquid.The preparation method of the present application improves the heat-resistant oxidized polyphenyl sulfide composite filter material heat-resistant oxidation, service life and filtration efficiency.

Description

Technical Field

[0001] This invention relates to the field of industrial dust removal filter material technology, specifically to a heat-resistant oxidized polyphenylene sulfide composite filter material, its preparation method, and its application. Background Technology

[0002] With the promulgation and implementation of a series of stringent environmental regulations, the application fields of air filtration equipment and materials have experienced tremendous development in the past decade and continue to accelerate in terms of technical performance and economic benefits. Baghouse dust collectors are one of the environmental protection devices for high-temperature flue gas purification and filtration, and filter bags are the core component of baghouse dust collectors, with filter media being the main raw material for these bags. Currently, commonly used high-temperature resistant filter materials mainly include polyphenylene sulfide (PPS) fiber needle-punched felt, polyimide (P84) fiber needle-punched felt, polytetrafluoroethylene (PTFE) fiber needle-punched felt, and glass fiber filter media. Among these, polyphenylene sulfide (PPS) nonwoven fabric is one of the most chemically resistant and cost-effective materials for removing pollutants from power plant exhaust gases.

[0003] Polyphenylene sulfide (PPS) is a semi-crystalline thermoplastic polymer with excellent comprehensive properties, including good thermal stability, chemical stability, and corrosion resistance. Compared with high-performance materials such as polyimide, polytetrafluoroethylene (PTFE), and aramid, PPS also has advantages such as easier spinning, better spinnability, and lower price. Therefore, PPS is widely used in high-temperature filtration and chemical corrosion resistant industries, becoming the preferred filter material for flue gas dust removal in coal-fired power plants and boilers. However, due to the low C-S bond energy of the PPS macromolecule, it is easily broken at high temperatures and reacts with oxygen in the air to undergo oxidation and cross-linking. During fiber processing, the melt viscosity of PPS is unstable, and the resulting fibers tend to darken in color. Furthermore, it suffers significant strength loss and shortened service life under high-temperature conditions, severely impacting its application as a high-temperature filter material in high-temperature flue gas dust removal. Furthermore, because polyphenylene sulfide (PPS) itself lacks hydrophobic properties, when low-temperature, high-humidity flue gas passes through PPS fiber filter media, dust often accumulates on the surface, leading to bag clogging and caking. This results in difficulties in cleaning the filter bags and increased pressure differential in the dust collection system, severely impacting its normal operation. Therefore, modifying PPS to enhance its antioxidant and hydrophobic properties is a crucial issue that urgently needs to be addressed and a pressing requirement in the environmental protection field. Summary of the Invention

[0004] The purpose of this invention is to provide a heat-resistant oxidized polyphenylene sulfide composite filter material, its preparation method, and its application, thereby solving the following technical problems:

[0005] Existing polyphenylene sulfide filter media suffer from poor heat and oxidation resistance, poor hydrophobicity, and short service life.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material includes at least the following preparation steps:

[0008] Polyphenylene sulfide resin and antioxidant modified nano-silica are added to a twin-screw extruder and then melted, mixed, dispersed, extruded, pelletized, and spun to obtain modified polyphenylene sulfide fiber;

[0009] The modified polyphenylene sulfide fibers are needle-punched onto the base fabric to obtain composite polyphenylene sulfide filter material;

[0010] The composite polyphenylene sulfide filter material is added to a modified polytetrafluoroethylene finishing solution, impregnated, rolled, and baked to obtain a heat-resistant oxidized polyphenylene sulfide composite filter material.

[0011] The antioxidant modified nano-silica is nano-silica loaded with antioxidant 3114, and the modified polytetrafluoroethylene finishing liquid includes antioxidant 168.

[0012] As a further aspect of the present invention: the content of nano-silica in the modified polyphenylene sulfide fiber is 1-2%, the content of antioxidant 3114 is 0.2-0.3%, and the needle-punching density of the modified polyphenylene sulfide fiber is 600-800 needles / cm².

[0013] As a further aspect of the present invention: the concentration of the modified polytetrafluoroethylene finishing liquid is 60-70 g / L, the impregnation time is 3-5 min, the roll residue rate is 70-80%, the baking time is 6-8 min, and the baking temperature is 190-210℃.

[0014] As a further aspect of the present invention, the preparation method of the antioxidant modified nano-silica includes the following steps:

[0015] Nano-silica was dispersed in an aqueous ethanol solution, the pH was adjusted to 9, and silane coupling agent KH560 was added to react and obtain alkylated nano-silica.

[0016] Antioxidant 3114 was added to the alkylated nano silica, and after stirring, centrifugation, filtration and drying, antioxidant modified nano silica was obtained.

[0017] As a further aspect of the present invention: the mass ratio of the nano-silica, silane coupling agent and antioxidant is 1-2:0.25-3:0.2-0.3.

[0018] As a further aspect of the present invention, the preparation method of the modified polytetrafluoroethylene finishing liquid includes the following steps:

[0019] Polytetrafluoroethylene dispersion, acrylic adhesive, waterborne epoxy resin and antioxidant 168 were added to a mixing tank and stirred at room temperature and pressure. Water and nonionic penetrant were added while stirring to adjust the pH to 7-9, thus obtaining modified polytetrafluoroethylene finishing solution.

[0020] As a further aspect of the present invention: the solid content of the polytetrafluoroethylene dispersion is 60%, the solid content of the acrylate adhesive is 40%, the solid content of the waterborne epoxy resin is 35%, and the mass ratio of the polytetrafluoroethylene dispersion, the acrylate adhesive, the waterborne epoxy resin, the antioxidant 168, and the nonionic penetrant is 70-75:15-20:3-6:0.1-0.3:0.5-2.

[0021] As a further aspect of the present invention: the base fabric is one of glass fiber cloth, polyphenylene sulfide fiber cloth or polytetrafluoroethylene fiber cloth.

[0022] A heat-resistant oxidized polyphenylene sulfide composite filter material is prepared by any of the preparation methods described above.

[0023] Application of heat-resistant oxidized polyphenylene sulfide composite filter material as described in any of the above-mentioned items in dust collector filter bags.

[0024] The beneficial effects of this invention are:

[0025] The heat-resistant oxidized polyphenylene sulfide (PPS) composite filter media provided by this invention improves the PPS filter media's high-temperature resistance, oxidation resistance, corrosion resistance, hydrophobicity, and anti-condensation bag-clogging properties by needle-punching modified PPS fibers onto the filter media base fabric and impregnating the filter media with modified polytetrafluoroethylene finishing liquid to form a hydrophobic coating. This also extends the filter media's service life and improves the filtration efficiency of needle-punched felt filter media. The heat-resistant oxidized PPS composite filter media prepared by this invention can be widely used in flue gas treatment in high-temperature industrial environments such as waste incineration plants, steel plants, cement plants, and thermal power plants. Furthermore, the preparation method of the heat-resistant oxidized PPS composite filter media proposed in this invention is suitable for continuous production processes of industrial nonwoven fabrics, giving PPS fibers and their fabrics (non-woven fabrics) a longer service life at higher ambient operating temperatures.

[0026] In this invention, antioxidant 3114 is introduced into polyphenylene sulfide modified fibers by loading antioxidant 3114 onto nano-silica. Antioxidant 3114 is present on the surface of nano-silica and is fixed on its surface in the form of chemical bonding. The number of hydroxyl groups on its surface is reduced, the interaction force between particles is weakened, and the agglomeration phenomenon is improved. At the same time, the combined addition of nano-silica and antioxidant reduces the grain size, which plays a role in refining the grains, making the PPS crystals tightly packed, improving the degree of crystallization perfection, and improving the mechanical properties of PPS fibers. This invention also introduces antioxidant 168 into the heat-resistant oxidizing polyphenylene sulfide composite filter material through a modified polytetrafluoroethylene finishing liquid. This results in the simultaneous introduction of antioxidants 3114 and 168 into the prepared heat-resistant oxidizing polyphenylene sulfide composite filter material. Antioxidant 3114, as a high molecular weight hindered phenolic antioxidant, interrupts the chain oxidation reaction by capturing free radicals. Antioxidant 168, as a phosphite compound, mainly decomposes hydroperoxides (ROOH) into stable alcohols, preventing them from further decomposing into free radicals. The two antioxidants produce a synergistic antioxidant effect: antioxidant 168 inhibits the generation of free radicals, and antioxidant 3114 reduces free radical precursors, prolonging the oxidation induction period of the material. This improves the heat resistance and oxidation performance of the heat-resistant oxidizing polyphenylene sulfide composite filter material and extends its service life. Furthermore, in this invention, the two antioxidants are introduced into the filter media in different steps. Antioxidant 3114 has a high decomposition temperature and can be directly introduced into PPS fibers. Antioxidant 168 has a decomposition temperature lower than that of PPS. Antioxidant 168 is introduced into the antioxidant system through modified polytetrafluoroethylene finishing liquid, avoiding the decomposition and failure of antioxidants due to excessively high processing temperature.

[0027] This invention utilizes a modified polytetrafluoroethylene (PTFE) finishing liquid that also includes acrylate adhesives and waterborne epoxy resins. The acrylate adhesives and epoxy resins have polar groups on their molecules, which attract each other to the polar groups on PPS fibers, resulting in intermolecular interactions and achieving a better adhesion effect. This allows the modified PTFE finishing liquid to form a hydrophobic coating on the polyphenylene sulfide (PPS) filter media. The coating system helps to construct a hydrophobic fiber and fabric surface, reducing the impact of moisture and acidic gases on the PPS fibers. Simultaneously, by adjusting the finishing process, the pore structure stability of the PPS filter fiber nonwoven fabric is enhanced, further improving the mechanical properties of the filter material and its ability to capture airborne particulate matter, thus increasing filtration efficiency. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: The preparation method of modified silica includes the following steps:

[0030] 10g of nano-silica was added to an ethanol-water solution (ethanol to water volume ratio of 1:1), the pH was adjusted to 9 with 0.1mol / L ammonia, and the solution was placed in an ultrasonic cleaner. After ultrasonication for 30min, 2g of silane coupling agent KH560 was added dropwise to the reaction system at a rate of 1g / min using a constant pressure funnel. The reaction was carried out under ultrasonic temperature of 40℃, ultrasonic power of 80W, and stirring speed of 300r / min for 30min to obtain alkylated nano-silica.

[0031] 2.5g of antioxidant 3114 was slowly added to the above-obtained reaction system. The reaction system was then subjected to oscillation reaction again at 40℃, 80W ultrasonic power and 300r / min stirring speed for 50min. After centrifugation twice, filtration, drying in a vacuum oven at 120℃ for 8h, and grinding with a ball mill, antioxidant modified nano silica was obtained.

[0032] Example 2: The preparation method of modified silica includes the following steps:

[0033] 10g of nano-silica was added to an ethanol-water solution (ethanol to water volume ratio of 1:1), the pH was adjusted to 9 with 0.1mol / L ammonia, and the solution was placed in an ultrasonic cleaner. After ultrasonication for 30min, 2g of silane coupling agent KH560 was added dropwise to the reaction system at a rate of 1g / min using a constant pressure funnel. The reaction was carried out under ultrasonic temperature of 40℃, ultrasonic power of 80W, and stirring speed of 300r / min for 30min to obtain alkylated nano-silica.

[0034] 3g of antioxidant 3114 was slowly added to the above-obtained reaction system. The reaction system was then subjected to oscillation reaction again at 40℃, 80W ultrasonic power and 300r / min stirring speed for 50min. After centrifugation twice, filtration, drying at 120℃ in a vacuum oven for 8h, and grinding with a ball mill, antioxidant modified nano silica was obtained.

[0035] Example 3: The preparation method of the modified polytetrafluoroethylene finishing liquid includes the following steps:

[0036] 75 parts by weight of 60% polytetrafluoroethylene dispersion, 20 parts by weight of 40% acrylic ester adhesive, 5 parts by weight of waterborne epoxy resin, and 0.2 parts by weight of antioxidant 168 were added to a mixing tank and stirred at room temperature and pressure. While stirring, water and 0.6 parts by weight of nonionic penetrant were added to adjust the pH to 7, thus obtaining the modified polytetrafluoroethylene finishing solution.

[0037] Example 4: A method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material, comprising the following steps:

[0038] 99 parts by weight of polyphenylene sulfide resin and 1 part by weight of antioxidant modified nano-silica prepared in Example 1 were added to a twin-screw extruder and melted, mixed, dispersed, extruded and pelletized. The screw diameter was 15 mm, the screw length-to-diameter ratio L / D = 12, the screw speed was 30 r / min, the feed port temperature and the extrusion port temperature of the twin-screw extruder were 300℃ and 305℃ respectively, and the melt mixing time was 10 min to obtain masterbatch. The masterbatch was spun in one step using a spinning method with a spinning speed set at 880 m / min, a pump feed rate of 22 g / min, and a draw ratio of 4.5 to obtain modified polyphenylene sulfide fiber.

[0039] The modified polyphenylene sulfide fibers were needle-punched onto polyphenylene sulfide fiber cloth at a needle-punching density of 700 needles / cm² to obtain composite polyphenylene sulfide filter material.

[0040] The above-mentioned composite polyphenylene sulfide filter material was added to the modified polytetrafluoroethylene finishing liquid prepared in Example 3 at a bath ratio of 10:1 and an impregnation time of approximately 5 minutes. Excess liquid was then removed using a rolling mill, maintaining a roll residue of approximately 80%. The rolled sample was pre-dried at 100°C for 3 minutes, and then placed in a shaping dryer and baked at 200°C for 6 minutes to obtain a heat-resistant oxidized polyphenylene sulfide composite filter material.

[0041] Example 5: A method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material, comprising the following steps:

[0042] 99 parts by weight of polyphenylene sulfide resin and 1 part by weight of antioxidant modified nano-silica prepared in Example 2 were added to a twin-screw extruder and melted, mixed, dispersed, extruded and pelletized. The screw diameter was 15 mm, the screw length-to-diameter ratio L / D=12, the screw speed was 30 r / min, the feed port temperature and the extrusion port temperature of the twin-screw extruder were 300℃ and 305℃ respectively, and the melt mixing time was 10 min to obtain masterbatch. The masterbatch was spun in one step using a spinning method with a spinning speed set at 880 m / min, a pump feed rate of 22 g / min, and a draw ratio of 4.5 to obtain modified polyphenylene sulfide fiber.

[0043] The modified polyphenylene sulfide fibers were needle-punched onto polyphenylene sulfide fiber cloth at a needle-punching density of 700 needles / cm² to obtain composite polyphenylene sulfide filter material.

[0044] The above-mentioned composite polyphenylene sulfide filter material was added to the modified polytetrafluoroethylene finishing liquid prepared in Example 3 at a bath ratio of 10:1 and an impregnation time of approximately 5 minutes. Excess liquid was then removed using a rolling mill, maintaining a roll residue of approximately 80%. The rolled sample was pre-dried at 100°C for 3 minutes, and then placed in a shaping dryer and baked at 200°C for 6 minutes to obtain a heat-resistant oxidized polyphenylene sulfide composite filter material.

[0045] Example 6: A method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material, comprising the following steps:

[0046] 98 parts by weight of polyphenylene sulfide resin and 2 parts by weight of antioxidant modified nano-silica prepared in Example 1 were added to a twin-screw extruder and melted, mixed, dispersed, extruded and pelletized. The screw diameter was 15 mm, the screw length-to-diameter ratio L / D=12, the screw speed was 30 r / min, the feed port temperature and the extrusion port temperature of the twin-screw extruder were 300℃ and 305℃ respectively, and the melt mixing time was 10 min to obtain masterbatch. The masterbatch was spun in one step using a spinning method with a spinning speed set at 880 m / min, a pump feed rate of 22 g / min, and a draw ratio of 4.5 to obtain modified polyphenylene sulfide fiber.

[0047] The modified polyphenylene sulfide fibers were needle-punched onto polyphenylene sulfide fiber cloth at a needle-punching density of 650 needles / cm² to obtain composite polyphenylene sulfide filter material.

[0048] The above-mentioned composite polyphenylene sulfide filter material was added to the modified polytetrafluoroethylene finishing liquid prepared in Example 3 at a bath ratio of 10:1 and an impregnation time of approximately 3 minutes. Excess liquid was then removed using a rolling mill, maintaining a roll residue of approximately 70%. The rolled sample was pre-dried at 100°C for 3 minutes, and then placed in a shaping dryer and baked at 200°C for 6 minutes to obtain a heat-resistant oxidized polyphenylene sulfide composite filter material.

[0049] Example 7: A method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material, comprising the following steps:

[0050] 98 parts by weight of polyphenylene sulfide resin and 2 parts by weight of antioxidant modified nano-silica prepared in Example 2 were added to a twin-screw extruder and melted, mixed, dispersed, extruded and pelletized. The screw diameter was 15 mm, the screw length-to-diameter ratio L / D=12, the screw speed was 30 r / min, the feed port temperature and the extrusion port temperature of the twin-screw extruder were 300℃ and 305℃ respectively, and the melt mixing time was 10 min to obtain masterbatch. The masterbatch was spun in one step using a spinning method with a spinning speed set at 880 m / min, a pump feed rate of 22 g / min, and a draw ratio of 4.5 to obtain modified polyphenylene sulfide fiber.

[0051] The modified polyphenylene sulfide fibers were needle-punched onto polyphenylene sulfide fiber cloth at a needle-punching density of 700 needles / cm² to obtain composite polyphenylene sulfide filter material.

[0052] The above-mentioned composite polyphenylene sulfide filter material was added to the modified polytetrafluoroethylene finishing liquid prepared in Example 3 at a bath ratio of 10:1 and an impregnation time of approximately 3 minutes. Excess liquid was then removed using a rolling mill, maintaining a roll residue of approximately 70%. The rolled sample was pre-dried at 100°C for 3 minutes, and then placed in a shaping dryer and baked at 200°C for 6 minutes to obtain a heat-resistant oxidized polyphenylene sulfide composite filter material.

[0053] Compared with Example 4, Comparative Example 1 replaced the antioxidant modified nano-silica prepared in Example 1 with unmodified nano-silica in Example 4 by the same mass. The remaining components and preparation methods were completely the same as in Example 4.

[0054] Comparative Example 2: The preparation method of the polytetrafluoroethylene finishing solution includes the following steps:

[0055] 75 parts by weight of 60% polytetrafluoroethylene dispersion, 20 parts by weight of 40% acrylic ester adhesive, and 5 parts by weight of waterborne epoxy resin were added to a mixing tank and stirred at room temperature and pressure. While stirring, water and 0.6 parts by weight of nonionic penetrant were added to adjust the pH to 7, thus obtaining the polytetrafluoroethylene finishing solution.

[0056] In the preparation steps of the heat-resistant oxidized polyphenylene sulfide composite filter material, compared with Example 4, Comparative Example 2 added the composite polyphenylene sulfide filter material obtained in Example 4 to the polytetrafluoroethylene finishing liquid obtained in Comparative Example 2, and the remaining components and preparation methods were completely consistent with Example 4.

[0057] Compared with Example 4, Comparative Example 3 omits the step of needle-punching the modified polyphenylene sulfide fiber onto the polyphenylene sulfide fiber cloth, while the remaining components and preparation methods are completely consistent with Example 4.

[0058] Compared with Example 4, Comparative Example 4 omits the step of treating the composite polyphenylene sulfide filter material with the modified polytetrafluoroethylene finishing liquid prepared in Example 3, while the remaining components and preparation methods are completely consistent with Example 4.

[0059] Compared with Example 4, Comparative Example 5 replaced the modified silica prepared in Example 1 with an equal amount of nano silica, while the remaining components and preparation methods were completely consistent with Example 4.

[0060] Compared with Example 4, Comparative Example 6 replaced the antioxidant modified nano-silica prepared in Example 1 with an equal mass of alkylated nano-silica and antioxidant 3114 in Example 4. The remaining components and preparation methods were completely consistent with Example 4.

[0061] Performance testing

[0062] Mechanical properties: The mechanical properties of the fiber samples were tested using a YG061FQ semi-automatic tensile strength tester according to GB / T14344-2008. The fiber length was 250 mm, and the tensile rate was 150 mm / min. The fiber breaking strength was obtained. Experimental environment: temperature 25℃, relative humidity 65%; the test results are shown in Table 1.

[0063] Heat oxidation resistance: The fiber samples were placed in a KSL-1200X box-type high-temperature sintering furnace, air was introduced, the temperature was set to 200℃, and the samples were removed after 30 days. The color change was observed, and the tensile strength of the treated fiber samples was tested using a YG061FQ semi-automatic tensile strength tester according to the above fiber mechanical characterization method. The results were compared with those of the fiber samples before treatment. The test results are shown in Table 1.

[0064] Water repellency: Pre-humidify the test sample and clamp it on the sample frame. Then install the sample frame on the fixed base of the water repellency tester, with the base plane at a 45° angle to the horizontal plane. Pour 250 mL of distilled water at 20℃±2℃ or deionized water at 27℃±2℃ into the fixed funnel smoothly and quickly. Spray the sample continuously through the nozzle, ensuring a continuous spraying time of 25-30 seconds. The distance between the nozzle and the center of the sample is 150 mm. After spraying, remove the sample frame from the base, tap it lightly twice, and then evaluate the water repellency of the fabric by comparing it with the rating standard text and the water resistance evaluation sample photo.

[0065] The rating criteria are as follows:

[0066] Level 1 – The entire surface of the fabric being sprayed is wetted;

[0067] Level 2 – Half of the surface of the fabric being wetted is wetted, and the wetted area consists of small, unconnected patches, with the total wetted area reaching half of the total area.

[0068] Level 3 – The surface of the fabric being wetted has a small area of ​​moisture, and the moisture is not continuous;

[0069] Level 4 – The surface of the fabric being drenched is not wet, but water droplets are present;

[0070] Level 5 – The surface of the fabric being sprayed is not wetted and does not have any small water droplets; test results are shown in Table 1.

[0071] Filtration efficiency: The filtration efficiency was tested using a counting method. The number of dust particles before and after filtration was recorded, and the filtration efficiency was calculated using a formula. The percentage of captured particles to the original number of particles is the filtration efficiency. Filtered particles ≥2μm were tested after the filter media was treated at 200℃ for 72 hours.

[0072]

[0073] In the formula: η is the filtration efficiency, %; n1 is the number of particles captured; n2 is the number of particles contained upstream; the detection results are shown in Table 1;

[0074] Table 1: Statistical Table of Performance Test Data of Polyphenylene Sulfide Composite Filter Media in Examples 4-7 and Comparative Examples 1-4

[0075]

[0076] As shown in Table 1, the heat-resistant oxidation-resistant polyphenylene sulfide composite filter material prepared by this invention involves needle-punching modified polyphenylene sulfide fibers containing antioxidants onto a base fabric and then coating it with a modified polytetrafluoroethylene finishing solution. The polyphenylene sulfide composite filter material prepared by this invention exhibits excellent heat resistance to oxidation, hydrophobicity, and anti-condensation bag-clogging properties. In Comparative Examples 1 and 2, only one antioxidant was introduced through modified polyphenylene sulfide fibers or modified polytetrafluoroethylene finishing solution, resulting in a decrease in the heat resistance to oxidation of the obtained composite filter material. In Comparative Example 3, no modified polyphenylene sulfide fibers containing antioxidants were needle-punched onto the base fabric, resulting in a decrease in both heat resistance to oxidation and mechanical properties of the obtained filter material. In Comparative Example 4, no modified polytetrafluoroethylene finishing solution treatment was performed, resulting in a decrease in both heat resistance to oxidation, water repellency, and filtration efficiency of the obtained filter material. In Comparative Example 5, the antioxidant introduced into the modified polyphenylene sulfide fibers was not combined with nano-silica, resulting in a slight decrease in the mechanical properties of the obtained filter material. This indicates that the two antioxidants have a synergistic antioxidant effect, and the addition of antioxidant-modified nano-silica can not only improve the heat resistance to oxidation but also improve the mechanical properties of the filter material.

[0077] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material, characterized in that, At least comprising the following preparation steps: The polyphenylene sulfide resin and the antioxidant modified nanosilica are added into a double screw extruder for melting, mixing, dispersing, extruding, granulating, and spinning to obtain modified polyphenylene sulfide fibers; The modified polyphenylene sulfide fibers are needled on a base cloth to obtain a composite polyphenylene sulfide filter material; The composite polyphenylene sulfide filter material is added into a modified polytetrafluoroethylene finishing liquid for dipping, calendering, and baking to obtain a heat-oxidation-resistant polyphenylene sulfide composite filter material. The antioxidant modified nanosilica is nanosilica loaded with antioxidant 3114, and the modified polytetrafluoroethylene finishing liquid contains antioxidant 168.

2. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 1, characterized in that, The content of the nano-silica in the modified polyphenylene sulfide fiber is 1-2%, the content of the antioxidant 3114 is 0.2-0.3%, and the needle punching density of the modified polyphenylene sulfide fiber is 600-800 punctures / cm 2 .

3. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 1, characterized in that, The concentration of the modified polytetrafluoroethylene finishing liquid is 60-70 g / L, the dipping time is 3-5 min, the calendering residual rate is 70-80%, the baking time is 6-8 min, and the baking temperature is 190-210℃.

4. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 1, characterized in that, The preparation method of the antioxidant modified nanosilica comprises the following steps: The nanosilica is dispersed in an ethanol aqueous solution, the pH is adjusted to 9, and silane coupling agent KH560 is added for reaction to obtain alkylated nanosilica; Antioxidant 3114 is added to the alkylated nanosilica, and after stirring, centrifugation, suction filtration, and drying, the antioxidant modified nanosilica is obtained.

5. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 4, characterized in that, The mass ratio of the nanosilica, the silane coupling agent, and the antioxidant is 1-2:0.25-3:0.2-0.

3.

6. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 1, characterized in that, The preparation method of the modified polytetrafluoroethylene finishing liquid comprises the following steps: The polytetrafluoroethylene dispersion, the acrylate adhesive, the water-based epoxy resin, and antioxidant 168 are added to a batching tank, and stirring is performed at normal temperature and pressure, while water and a non-ionic penetrant are added, the pH is adjusted to 7-9, and the modified polytetrafluoroethylene finishing liquid is prepared.

7. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 6, characterized in that, The solid content of the polytetrafluoroethylene dispersion is 60%, the solid content of the acrylate adhesive is 40%, the solid content of the water-based epoxy resin is 35%, and the mass ratio of the polytetrafluoroethylene dispersion, the acrylate adhesive, the water-based epoxy resin, antioxidant 168, and the non-ionic penetrant is 70-75:15-20:3-6:0.1-0.3:0.5-2.

8. The method for preparing a heat-resistant oxidized polyphenylene sulfide composite filter material according to claim 1, characterized in that, The base cloth is one of a glass fiber cloth, a polyphenylene sulfide fiber cloth, or a polytetrafluoroethylene fiber cloth.

9. A heat-oxidized polyphenylene sulfide composite filter material, characterized by, Prepared by the preparation method of any one of claims 1-8.

10. The heat-oxidation-resistant polyphenylene sulfide composite filter material of claim 9 is applied in a dust removal filter bag.

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