Oil-resistant and hydrolysis-resistant electrical insulating composite material and its preparation method and application

Abstract

The present invention relates to the technical field of electrical insulation materials, and specifically to an oil-resistant and hydrolysis-resistant electrical insulation composite material, a preparation method, and an application thereof. The composite material comprises a membrane material, a paper material adhered to both sides of the membrane material, and a glue for bonding. The membrane material is made of polyphenylene sulfide, and the pulp used to prepare the paper material comprises polyphenylene sulfide staple fibers, meta-aramid staple fibers, and meta-aramid precipitation slurry. The polyphenylene sulfide is prepared by polymerization of anhydrous sodium sulfide and dichlorobenzene, wherein the molar ratio of the anhydrous sodium sulfide to the dichlorobenzene is 1:(0.95-0.98). The dichlorobenzene comprises meta-dichlorobenzene and para-dichlorobenzene, and the molar ratio of the meta-dichlorobenzene to the para-dichlorobenzene is (3-4):1. The oil-resistant and hydrolysis-resistant electrical insulation composite material of the present invention has good mechanical and electrical properties, can meet the application requirements in motors, and the composite material has excellent insulation properties, while also having oil resistance and hydrolysis resistance.

Description

Technical Field

[0001] The invention relates to an oil-resistant and hydrolysis-resistant electrical insulating composite material, a preparation method and an application thereof, and belongs to the technical field of electrical insulating materials. Background Art

[0002] With the continuous development of society, the promotion of national policies, and the increasing awareness of environmental protection, the popularity of new energy vehicles is gradually increasing. This is inseparable from the development of new energy vehicle heat dissipation technology. As the driving force of pure electric new energy vehicles, the motor can achieve extremely low or zero emissions. During the driving and energy recovery process of pure electric vehicles, the stator core and stator windings of the motor will generate losses during movement. These losses are dissipated as heat. Therefore, an effective cooling medium and cooling method are required to remove this heat and ensure the safe and reliable operation of the motor in a stable ventilation system with balanced cooling and heating cycles.

[0003] High-temperature operating conditions negatively impact both motor efficiency and battery safety. Therefore, optimizing heat dissipation is a key development priority for future electric drive systems. The cooling units in new energy vehicles primarily include the power battery, drive motor, and electronic control system. Based on the practical application of traditional engine cooling technologies and new energy vehicle cooling, water cooling and air cooling are currently the two primary methods for dissipating heat in new energy vehicles.

[0004] Oil-cooled motors offer advantages over water-cooled motors, including direct contact, a larger contact area, and corrosion resistance. Currently, the most common motor cooling methods are air cooling, liquid cooling, and evaporative cooling. Air cooling offers low cost and high reliability, but suffers from poor heat dissipation, primarily used for low-power motors. Evaporative cooling utilizes a gas-liquid phase change cycle for efficient motor cooling, primarily used in very large machinery and equipment, and is unsuitable for automotive cooling.

[0005] Oil-cooled motors have the following advantages: 1) Oil is neither magnetic nor conductive, and can directly contact the windings and remove the generated heat. Water, on the other hand, can cause a short circuit if it comes into direct contact with the motor, and can only remove heat by flowing through specific pipes, which is less efficient. 2) Compared to oil, water is more likely to contain impurities or corrosive substances. Long-term use will not only corrode the system, but will also produce scale in the channels, shortening the life of the motor. In the future, oil cooling of drive motors will gradually replace water cooling, increasing both cooling efficiency and safety factors. Drive motors are currently developing towards high speeds and high torques, but given the trend towards integration, the internal space of the motors is becoming more compact, and the heat generated during operation has doubled. In addition, the heat dissipation space has been sharply reduced, posing a greater challenge to the cooling capacity of the system due to the heat generated by the stator windings and magnets.

[0006] Oil cooling involves spraying ATF oil directly onto the ends of the motor windings to dissipate heat. This direct contact between the insulation and the ATF oil, which also contains a small amount of water (typically below 5000 ppm), can degrade the insulation to a certain extent. Existing insulation materials, due to their poor oil resistance, experience long-term corrosion and hydrolysis from ATF oil, significantly degrading their performance, particularly electrical insulation performance, which severely impacts the reliability of oil-cooled motors. Consequently, the development of oil-cooled motors places higher demands on the insulation materials within the motors, requiring them to be both oil-corrosion-resistant and hydrolysis-resistant.

[0007] Currently, the majority of electrical insulation composite materials used in domestic oil-cooled motors are produced using imported raw materials, which are expensive. However, when fully immersed in a sealed tank containing a mixture of 99.5 vol% ATF and 0.2 vol% pure water (the liquid level of the "oil-water mixture" is 75% of the container depth), and subjected to high- and low-temperature cycling (155°C / 40 hours to -45°C / 8 hours per cycle) with a switching time of less than 5 minutes (two-chamber method, sample switching outside the chamber), the substrate readily detached during the winding process after eight cycles, significantly reducing the service life of the electrical insulation material. Therefore, when using these imported electrical insulation composite materials in oil-cooled motors using direct spray technology for electric vehicles, their winding and corona resistance life performance still needs to be improved.

[0008] Therefore, there is an urgent need to develop a composite material that is resistant to ATF oil, resistant to hydrolysis, and has excellent electrical insulation properties to meet the technical requirements of the development of oil-cooled motors. Summary of the Invention

[0009] In view of the deficiencies in the prior art, the present invention provides an oil-resistant and hydrolysis-resistant electrical insulating composite material, a preparation method and an application thereof. The composite material meets the strength performance requirements for use in motors and has good oil corrosion resistance and hydrolysis resistance.

[0010] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an oil-resistant and hydrolysis-resistant electrical insulating composite material, the composite material comprising a membrane material and paper materials adhered to both sides of the membrane material and glue acting as a bonding agent, the membrane material is made of polyphenylene sulfide, and the pulp for preparing the paper material comprises polyphenylene sulfide staple fibers, meta-aramid staple fibers and meta-aramid precipitation slurry.

[0011] Furthermore, the polyphenylene sulfide is prepared by polymerization reaction of anhydrous sodium sulfide and dichlorobenzene, the molar ratio of the anhydrous sodium sulfide to the dichlorobenzene is 1: (0.95-0.98), the dichlorobenzene includes meta-dichlorobenzene and para-dichlorobenzene, and the molar ratio of meta-dichlorobenzene to para-dichlorobenzene is (3-4):1.

[0012] Furthermore, in the pulp, the mass ratio of the polyphenylene sulfide staple fibers, the meta-aramid staple fibers and the meta-aramid precipitation slurry is (3-4): (2-3): (3-5).

[0013] Furthermore, the length of the polyphenylene sulfide staple fiber is 9-20 mm; the length of the meta-aramid staple fiber is 9-20 mm; the solid content of the meta-aramid fibrils in the meta-aramid precipitation slurry is 4-7%, the average length of the meta-aramid fibrils is 0.6-1.8 mm, and the specific surface area of the meta-aramid fibrils is 25-55 m 2 / g.

[0014] The present invention also discloses a method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material, the preparation method comprising:

[0015] S1. Preparation of polyphenylene sulfide pellets:

[0016] Under inert gas conditions, dichlorobenzene and anhydrous sodium sulfide are dissolved in a polar solvent, and a polymerization reaction is carried out under the action of an alkali metal salt. After the reaction is completed, polyphenylene sulfide pellets are obtained through post-treatment.

[0017] S2. Preparation of film and paper materials:

[0018] Film preparation: Polyphenylene sulfide pellets are melt-extruded into sheets, and then biaxially drawn and wound to obtain film;

[0019] Paper material preparation: polyphenylene sulfide pellets are melted into filaments to obtain polyphenylene sulfide staple fibers, and polyphenylene sulfide staple fibers, meta-aramid staple fibers and meta-aramid precipitated slurry are mixed and then papered to obtain paper material;

[0020] S3. Preparation of composite materials:

[0021] Glue is applied on both sides of the membrane material, dried, pressed with paper material, and cured to obtain a composite material.

[0022] Furthermore, in step S1, the polymerization reaction temperature is 180-270° C., the reaction pressure is 0-2 MPa, and the reaction time is 1-2 h.

[0023] Furthermore, the process of preparing the membrane material in step S2 is as follows:

[0024] The dried polyphenylene sulfide pellets are melted at high temperature and then extruded through a twin-screw extruder through a die to form a sheet, which is then bidirectionally drawn and wound to obtain a film.

[0025] The high temperature melting temperature is 270-320°C, and the extrusion pressure is 3.0-9.0 MPa;

[0026] The die is a slot extrusion die, the die holding time is 4-10 hours, and the die temperature is 100-180°C;

[0027] The drawing temperature is 130-270℃, the transverse drawing ratio is 1:(2-2.5), and the longitudinal drawing ratio is 1:(3-5).

[0028] Furthermore, the process of preparing the paper material in step S2 is as follows:

[0029] First, the meta-aramid precipitated pulp is beaten and dispersed, and the polyphenylene sulfide staple fiber and the meta-aramid staple fiber are debonded and dispersed to obtain debonded mixed fibers. Then, the precipitated pulp after beating and dispersion and the debonded mixed fibers are stirred and blended uniformly to obtain mixed pulp. The mixed pulp is subjected to flow forming, pressing and drying, hot pressing forming, and rewinding and slitting to obtain paper material.

[0030] The pressure of the pressing and drying is 1-3 MPa, and the temperature of the pressing and drying is 130-170°C;

[0031] The pressure of the hot pressing molding is 20-30 MPa, and the temperature of the hot pressing molding is 230-270°C.

[0032] Furthermore, in step S3, the amount of glue applied on one side of the membrane is 5-50 g / m 2 , the drying temperature is 50-150℃, the pressure during pressing is 0.3-0.6Mpa, and the pressing temperature is 35-70℃.

[0033] The invention also discloses an application of an oil-resistant and hydrolysis-resistant electrical insulation composite material, wherein the composite material is applied in a motor.

[0034] The beneficial effects of the present invention are:

[0035] The oil-resistant and hydrolysis-resistant electrical insulation composite material of the present invention has strength properties that meet the application requirements in motors. Furthermore, the composite material exhibits excellent insulation properties while also being oil-resistant and hydrolysis-resistant. The oil-resistant and hydrolysis-resistant electrical insulation composite material of the present invention can effectively extend the service life of the insulation material, improve the safety of motors, and thus, the safety of automobiles, thereby reducing the risk of accidents.

[0036] The oil-resistant and hydrolysis-resistant electrical insulation composite material described herein, through the interaction between the film and paper, achieves excellent electrical insulation performance while maintaining a certain stiffness, facilitating insertion into motors and preventing creases that could affect performance. Furthermore, the paper provides excellent strain and strain resistance, ensuring the composite meets appropriate bending requirements during motor use and preventing the film's brittleness from causing breakage. The incorporation of polyphenylene sulfide staple fibers into the paper enhances the oil and water resistance of the outer layer, strengthening the protective properties of the outer layer and further improving the oil and water resistance of the inner film. Furthermore, the paper protects the film, preventing components from scratching the primary insulating film during motor insertion, which could compromise insulation performance. The addition of appropriate polyphenylene sulfide staple fibers into the paper ensures that the paper provides both adequate strength and excellent oil and hydrolysis resistance, thereby enhancing the overall performance and service life of the composite material.

[0037] The preparation method described herein introduces sulfur atoms into the molecular backbone, alternating the benzene rings and sulfur atoms. The benzene rings enhance the material's rigidity, the sulfide improves the molecular flexibility, and the symmetrical molecular structure enhances the material's oil and water resistance. The introduction of the phenylene sulfide improves the material's stiffness, facilitating slot insertion during production and improving production efficiency. Furthermore, the symmetrical molecular structure and the introduction of sulfur atoms enhance the material's oil and water resistance, improving not only the membrane's oil and water resistance but also the protective properties of the outer paper material. This multi-layered protection enhances the overall composite material's oil and water resistance.

[0038] During the preparation of the paper material of the present invention, an appropriate amount of polyphenylene sulfide staple fibers is added, and in conjunction with appropriate calendering process conditions, the paper material avoids the problem of poor oil and water corrosion resistance caused by obvious fuzzing, thereby making the strength performance more excellent, and the paper material has better oil resistance and hydrolysis resistance. In addition, during the preparation of the polyphenylene sulfide pellets of the present invention, the appropriate ratio of meta-dichlorobenzene and para-dichlorobenzene is combined, so that the strength performance of the film prepared from the polyphenylene sulfide pellets is more suitable, that is, it can avoid the problem of excessive rigidity causing creases and breakage, thereby affecting the breakdown voltage of the material, and can also avoid the material being too soft and prone to creases, which affects the smooth insertion of the composite material in the motor and affects production efficiency. In addition, the flexibility and strength performance of the film are suitable, which can better broaden the material's application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of the oil-resistant and hydrolysis-resistant electrical insulation composite material of the present invention;

[0040] Figure 2Comparison diagram of the composite material prepared in Example 1 before and after the oil resistance test;

[0041] Figure 3 Comparison diagram of the composite material prepared in Comparative Example 1 before and after the oil resistance test;

[0042] Figure 4 This is a comparison chart of the composite materials of Example 1 and Comparative Example 1 after 8 cycles of oil resistance testing. DETAILED DESCRIPTION

[0043] The present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used are only for describing specific embodiments and are not intended to limit the present invention.

[0045] An oil-resistant and hydrolysis-resistant electrical insulation composite material, the composite material comprises a film material and paper materials adhered to both sides of the film material and glue for bonding, the structure of the composite material is as follows Figure 1 As shown, the paper material is attached to both sides of the membrane material through the adhesive layer. The membrane material is made of polyphenylene sulfide, and the pulp for preparing the paper material includes polyphenylene sulfide staple fibers, meta-aramid staple fibers and meta-aramid precipitated slurry.

[0046] In the embodiment of the present invention, the film material thickness is 45-55 μm, the paper material thickness is 45-55 μm, and the total thickness of the composite material is 190-230 μm. The thickness of each substrate and the total thickness of the composite material can be adjusted according to the application scenario. In addition, multi-layer composite materials can be used, such as two-layer, three-layer, or five-layer composite materials, depending on the application scenario, and are not limited to the three-layer structure described in the embodiment of the invention.

[0047] In an embodiment of the present invention, a method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material is provided, and the preparation method includes the following steps S1-S8. However, it should be noted that the order of steps S1-S8 is not a limitation on the order of steps in the preparation method of this application. For example, there is no strict requirement for the order of steps S1 and S2 below. The specific preparation method shall be subject to the scope of the claims (the same applies to other steps). Here, the entire preparation process is set to steps S1-S8 just for the sake of clarity.

[0048] A method for preparing an oil-resistant and hydrolysis-resistant electrical insulation composite material, the preparation method comprising:

[0049] S1. Preparation of polyphenylene sulfide pellets;

[0050] S2, preparation of polymerization solution;

[0051] S3, preparation of membrane materials;

[0052] S4, preparation of polyphenylene sulfide staple fibers;

[0053] S5. Preparation of meta-aramid staple fibers;

[0054] S6. Preparation of meta-aramid precipitation slurry;

[0055] S7, preparation of paper;

[0056] S8. Preparation of composite materials.

[0057] The specific process methods involved in the above steps S1-S8 are as follows:

[0058] S1, the preparation process of polyphenylene sulfide pellets is:

[0059] Sodium sulfide is directly heated under vacuum to dehydrate, and then dichlorobenzene and anhydrous sodium sulfide are dissolved in a polar solvent under an inert gas atmosphere. Then, a polymerization reaction is carried out under the action of an alkali metal salt to obtain a solid-liquid mixture, which is filtered, washed with water, and dried to obtain polyphenylene sulfide pellets.

[0060] The reaction principle of polyphenylene sulfide pellets is:

[0061] .

[0062] The meaning of n in the above polymer structure is that the polymer structural unit is set repeatedly and no specific data needs to be set.

[0063] The reaction mechanism of the polyphenylene sulfide pellets described above is as follows: a mixture of m-dichlorobenzene and p-dichlorobenzene in a certain ratio reacts with sodium sulfide to form a polymer containing m-phenylene sulfide, p-phenylene sulfide, and fragments interspersed with m-phenylene and p-phenylene sulfide. The presence of m-phenylene sulfide fragments and poly-m-phenylene sulfide enhances the flexibility of the polymer after molding, while the presence of p-phenylene sulfide fragments and poly-p-phenylene sulfide enhances the rigidity of the molded material.

[0064] In step S1, the dehydration conditions are: vacuum degree ≥ 0.096 MPa, heating at 85-90° C. for 0.8-1.2 h; heating at 115-118° C. for 0.4-0.6 h, and finally cooling the material to ≤ 40° C. under vacuum conditions to obtain dry anhydrous sodium sulfide.

[0065] In step S1, the inert gas is at least one of nitrogen and argon.

[0066] The polar solvent in step S1 is one or more of N-methylpyrrolidone (NMP), hexamethylphosphoramide (HMPA), N,N-dimethylacetamide, N-methylcaprolactam, and pyridine; preferably N-methylpyrrolidone (NMP).

[0067] In step S1, the molar ratio of the anhydrous sodium sulfide to dichlorobenzene is 1:(0.95-0.98); the dichlorobenzene includes meta-dichlorobenzene and para-dichlorobenzene, and the molar ratio of meta-dichlorobenzene to para-dichlorobenzene is (3-4):1.

[0068] In step S1, the alkali metal salt includes one or more of sodium carbonate, potassium carbonate, sodium hydroxide, benzoate and phosphate, which serve as catalysts and auxiliary agents to accelerate the reaction.

[0069] In step S1, the polymerization reaction conditions are: reaction pressure 0-2 MPa, polymerization temperature 180-270° C., and reaction time 1-2 hours.

[0070] S2, the preparation process of the polymer solution is:

[0071] Dissolve m-phenylenediamine in a polar solvent, add part of isophthaloyl chloride for prepolymerization, add neutralizer 1 to adjust the pH, and filter to obtain the prepolymer liquid. Add the remaining isophthaloyl chloride in the raw material formula to the prepolymer liquid for post-polymerization, and then add neutralizer 2 to adjust the pH to obtain the polymerization liquid with a viscosity of 600-1500 Po.

[0072] The polymerization reaction equation of the polymer solution is:

[0073] .

[0074] The meaning of n in the above polymer structure is that the polymer structural unit is set repeatedly and no specific data needs to be set.

[0075] In step S2, the mass concentration of the m-phenylenediamine in the polar solvent is 8%-14%.

[0076] In step S2, the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:(0.98-1.06).

[0077] In step S2, the polar solvent is one or more of N-methylpyrrolidone (NMP), hexamethylphosphoramide (HMPA), N,N-dimethylacetamide, N-methylcaprolactam, and pyridine, preferably N,N-dimethylacetamide.

[0078] In step S2, the prepolymerization reaction temperature is -5°C to 5°C, and the prepolymerization reaction time is 20-40 minutes. The portion of isophthaloyl chloride added during the prepolymerization is 80-95% of the total mass of the isophthaloyl chloride in the formula. The neutralizing agent 1 is aqueous ammonia, and the pH during the prepolymerization is adjusted to 6.7-7.2.

[0079] In step S2, the post-polymerization reaction temperature is 20°C-40°C, and the post-polymerization reaction time is 10-30 minutes. The residual isophthaloyl chloride added during the post-polymerization process is 5-20% of the total mass of the isophthaloyl chloride in the formulation. The neutralizer 2 is any one or a combination of methylamine, dimethylamine, ethylamine, and diethylamine. The pH of the post-polymerization reaction is adjusted to 6.9-7.6.

[0080] S3. The preparation process of membrane material is as follows:

[0081] The polyphenylene sulfide pellets are dried under vacuum conditions, melted at high temperature, and then extruded through a twin-screw extruder through a die to form a sheet, which is then bidirectionally stretched and wound to form a film.

[0082] In step S3, the drying vacuum degree is 0.01-0.02 MPa, the drying temperature is 110-140° C., and the drying time is 3-5 h.

[0083] In step S3, the melting temperature is 270-320° C., and the extrusion pressure is 3.0-9.0 MPa.

[0084] In step S3, the mold is a slit extrusion mold, the mold insulation time is 4-10 hours, and the mold temperature is 100-180°C.

[0085] In step S3, the stretching temperature is 130-270°C, the transverse stretching ratio is 1:(2-2.5), and the longitudinal stretching ratio is 1:(3-5).

[0086] S4, the preparation process of polyphenylene sulfide staple fiber is:

[0087] The polyphenylene sulfide pellets are dried under vacuum conditions, and the dried polyphenylene sulfide pellets are melt-extruded into nascent fibers through a twin-screw extruder at high temperature, and polyphenylene sulfide staple fibers are obtained through the processes of heat drawing, heat setting, and slitting.

[0088] In step S4, the drying vacuum degree is 0.01-0.02 MPa, the drying temperature is 110-140° C., and the drying time is 3-5 hours.

[0089] In step S4, the high temperature melting temperature is 290-330° C., and the extrusion pressure is 1.0-6.0 MPa.

[0090] In step S4, the hot stretching temperature is 140-270° C., and the stretching ratio is 1:(4-7).

[0091] In step S4, the heat setting temperature is 250-320°C, and the draw ratio is 1:(1-1.1).

[0092] S5. The preparation process of meta-aramid staple fiber is as follows:

[0093] The polymer solution is filtered, coagulated, washed, dried, heat-treated and cut to obtain the aramid staple fibers.

[0094] In step S5, the coagulation bath liquid is an aqueous solution of a polar solvent, and the mass concentration of the polar solvent in the coagulation bath liquid is in the range of 53%-63%, preferably 60%.

[0095] In step S5, the water washing is countercurrent washing.

[0096] In step S5, the drying temperature is 90-140°C.

[0097] In step S5, the heat treatment temperature is 280-330°C.

[0098] In step S5, the length of the aramid staple fibers is 9-20 mm.

[0099] S6. The preparation process of meta-aramid precipitation slurry is as follows:

[0100] Water, glycerin and chloride salt are mixed to prepare a mixed liquid, and then the mixed liquid is mixed with a polymer liquid in proportion to obtain a slurry. The slurry is subjected to high-speed shearing, cooling and forming, and multi-stage water washing to obtain the precipitation slurry.

[0101] In step S6, the mass ratio of water, glycerol, and chloride salt is (30-50):(45-60):(5-10); the chloride salt is any one or a combination of calcium chloride, lithium chloride, sodium chloride, magnesium chloride, and potassium chloride;

[0102] In step S6, the mass ratio of the mixed liquid to the polymerization liquid is (8-16):1.

[0103] In step S6, the high-speed shearing speed is 4000-7000 rpm / min, the temperature is 20-60° C., and the high-speed shearing time is 10-50 min.

[0104] In step S6, the cooling molding is performed in cold water at -10 to 5°C.

[0105] In step S6, the temperatures of the multi-stage water washing are as follows: first-stage water washing 10-20°C, second-stage water washing 30-40°C, third-stage water washing 50-60°C, fourth-stage water washing 70-80°C, and fifth-stage water washing 90-95°C, all of which are countercurrent water washing;

[0106] In step S6, the average length of the meta-aramid fiber in the meta-aramid fiber precipitation slurry is 0.6-1.8 mm, and the specific surface area is 25-55 m 2 / g; the solid content of the meta-aramid fiber precipitation slurry is 4-7%.

[0107] S7. The preparation process of the paper material is as follows:

[0108] First, the meta-aramid precipitated pulp is beaten and dispersed, and the polyphenylene sulfide staple fiber and the meta-aramid staple fiber are debonded and dispersed to obtain debonded mixed fibers. The precipitated pulp after beating and dispersion and the debonded mixed fibers are then stirred and blended to obtain mixed pulp. The mixed pulp is then subjected to flow forming, pressing and drying, hot pressing, and rewinding and slitting to obtain mixed paper materials.

[0109] In step S7, the mass ratio of the polyphenylene sulfide staple fiber, the meta-aramid staple fiber and the meta-aramid precipitation slurry is (3-4): (2-3): (3-5).

[0110] In step S7, the stirring speed of the stirring blending is 2000-4000 rpm / min, and the stirring time is 15-25 min.

[0111] In step S7, the pressure of the pressing and drying is 1-3 MPa and the temperature is 130-170°C.

[0112] In step S7, the pressure of the hot pressing molding is 20-30 MPa and the temperature is 230-270°C.

[0113] S8. The preparation process of the composite material is as follows:

[0114] After coating glue on both sides of the membrane material, drying it in a drying tunnel, and pressing both sides with paper material to prepare a composite material, that is, an oil-resistant and hydrolysis-resistant composite material, which can be used after being left to mature.

[0115] In step S8, the glue is a mixture of LA 2681 and LA 5094. The glue used in this embodiment is a mixture of LA 2681 and LA 5094 at a weight ratio of 20:(1-1.5). However, this is not a limitation of the present invention; any method that successfully bonds paper and film is within the scope of the present invention.

[0116] In step S8, the coating amount is 5-50g / m 2 .

[0117] In step S8, the drying tunnel temperature is 50-150°C.

[0118] In step S8, the pressing pressure is 0.3-0.6 MPa, and the pressing temperature is 35-70°C.

[0119] In step S8, the aging is carried out at a temperature of 25-90° C. for 2-6 days.

[0120] Example 1

[0121] The preparation of an oil-resistant and hydrolysis-resistant electrical insulation composite material comprises the following specific steps:

[0122] S1. Preparation of polyphenylene sulfide pellets:

[0123] Sodium sulfide is heated at a vacuum degree of 0.1 MPa and a temperature of 87°C for 1 hour, then the temperature is raised to 116°C and heated for 0.5 hour. The material is cooled to 39°C to obtain dehydrated anhydrous sodium sulfide. The anhydrous sodium sulfide is then dissolved in N-methylpyrrolidone under a nitrogen environment, and then 0.96 equivalents of dichlorobenzene (meta-dichlorobenzene and p-dichlorobenzene, with a molar ratio of 3.5:1) are added. The reaction is carried out under a reaction pressure of 1 MPa and a polymerization temperature of 230°C under the action of potassium carbonate for 1.5 hours to obtain a solid-liquid mixture. Finally, the mixture is filtered, washed with water, and dried to obtain polyphenylene sulfide pellets.

[0124] S2. Preparation of polymer solution:

[0125] Metaphenylenediamine was dissolved in N-methylpyrrolidone to prepare a solution with a mass concentration of 11%, 90% equivalent of isophthaloyl chloride was added, and the mixture was stirred at 0°C for 30 minutes for prepolymerization. Ammonia water was added to adjust the pH to 7.0, and the prepolymer solution was obtained after filtration. The remaining 10% equivalent of isophthaloyl chloride was added to the prepolymer solution, and the mixture was reacted at 30°C for 20 minutes. Diethylamine was then added to adjust the pH to 7.1 to obtain a polymerization solution with a viscosity of 900 Po.

[0126] S3. Preparation of membrane materials:

[0127] The polyphenylene sulfide pellets were dried at 125°C for 4 hours under a vacuum degree of 0.015 MPa, and then the dried polyphenylene sulfide pellets were melt-extruded through a twin-screw extruder at 295°C and a pressure of 6.0 MPa, and formed into a sheet through a 140°C slit extrusion die, and then bidirectionally stretched at 200°C with a transverse stretching ratio of 1:2.3 and a longitudinal stretching ratio of 1:4, and finally rolled into a film material with a thickness of 45 μm.

[0128] S4. Preparation of polyphenylene sulfide staple fibers:

[0129] Under a vacuum degree of 0.015MPa, the polyphenylene sulfide pellets are dried at 125°C for 4h, and then the dried polyphenylene sulfide pellets are melt-extruded through a twin-screw extruder at 310°C under a pressure of 4.0MPa to obtain spun fibers, which are then hot-stretched at 210°C with a stretch ratio of 1:6; then hot-stretched at 280°C with a stretch ratio of 1:1.05, and finally subjected to heat setting and slitting processes to obtain 15mm polyphenylene sulfide staple fibers.

[0130] S5. Preparation of meta-aramid staple fiber:

[0131] The polymer solution is filtered and passed through a spinneret to coagulate in a 58% N-methylpyrrolidone aqueous solution (coagulation bath) to form nascent fibers. After countercurrent water washing, the fibers are dried on a drying roller at 110°C. The dried fibers are heat treated in a channel at 305°C and finally cut into 14mm meta-aramid staple fibers.

[0132] S6. Preparation of meta-aramid precipitation slurry:

[0133] Water, glycerin, and chloride salt are mixed in a mass ratio of 40:53:7 to prepare a mixed liquid, and then the mixed liquid is mixed with a polymer solution in a weight ratio of 12:1 to obtain a slurry. The slurry is subjected to high-speed shearing at a speed of 6000 rpm / min for 30 minutes at a temperature of 40°C, and then cooled and formed in cold water at -1°C, and then subjected to multi-stage countercurrent washing, with the first stage at 15°C, the second stage at 35°C, the third stage at 55°C, the fourth stage at 75°C, and the fifth stage at 91°C, to obtain a meta-aramid precipitation slurry, wherein the average length of the meta-aramid precipitation fibers in the meta-aramid precipitation slurry is 1.2 mm, and the specific surface area is 32 m 2 / g.

[0134] S7. Preparation of paper materials:

[0135] First, the meta-aramid precipitated pulp is beaten and dispersed, and the polyphenylene sulfide staple fiber and the meta-aramid staple fiber are debonded and dispersed to obtain debonded mixed fibers. The mass ratio of polyphenylene sulfide staple fiber, meta-aramid staple fiber and meta-aramid precipitated pulp is 3.5:2.5:4. Then, the precipitated pulp and the debonded mixed fibers after beating and dispersion are stirred at a speed of 3000 rpm / min for 20 minutes to obtain mixed pulp. The mixed pulp is then formed by flow conveying, pressed and dried under a pressure of 2 MPa and a temperature of 150°C, and then hot-pressed at a pressure of 22 MPa and a temperature of 250°C. Finally, the mixed paper material is obtained after rewinding and slitting.

[0136] S8. Preparation of composite materials:

[0137] Coat both sides of the membrane with 35g / m 2 After gluing, the sheets were dried in a 90°C oven. The sheets were then pressed together with paper at 0.5 MPa and 45°C to form a composite material that was oil-resistant and hydrolysis-resistant. The composite material was then matured at 70°C for three days before use. The thickness of the composite material was 210 μm.

[0138] Example 2

[0139] The preparation of an oil-resistant and hydrolysis-resistant electrical insulation composite material comprises the following specific steps:

[0140] S1. Preparation of polyphenylene sulfide pellets:

[0141] Sodium sulfide is heated at a vacuum degree of 0.1 MPa and a temperature of 90°C for 0.8 h, then the temperature is raised to 118°C and heated for 0.4 h. The material is cooled to 39°C to obtain dehydrated anhydrous sodium sulfide. The anhydrous sodium sulfide is then dissolved in N-methylpyrrolidone under a nitrogen environment, and then 0.95 equivalents of dichlorobenzene (meta-dichlorobenzene and p-dichlorobenzene, with a molar ratio of 3:1) are added. The mixture is reacted for 2 hours under the action of sodium carbonate at a reaction pressure of 2 MPa and a polymerization temperature of 180°C to obtain a solid-liquid mixture. Finally, the mixture is filtered, washed with water, and dried to obtain polyphenylene sulfide pellets.

[0142] S2. Preparation of polymer solution:

[0143] m-Phenylenediamine was dissolved in N,N-dimethylacetamide to prepare a solution with a mass concentration of 14%, 80% equivalent of isophthaloyl chloride was added, and the mixture was stirred at -5°C for 30 minutes for prepolymerization. Ammonia water was added to adjust the pH to 7.0, and the prepolymer solution was obtained after filtration. The remaining 20% equivalent of isophthaloyl chloride was added to the prepolymer solution, and the mixture was reacted at 40°C for 10 minutes. Diethylamine was then added to adjust the pH to 7.2 to obtain a polymerization solution with a viscosity of 1050 Po.

[0144] S3. Preparation of membrane materials:

[0145] The polyphenylene sulfide pellets were dried at 110°C for 5 hours under a vacuum degree of 0.02 MPa, and then the dried polyphenylene sulfide pellets were melt-extruded through a twin-screw extruder at 320°C and a pressure of 3.0 MPa, and formed into a sheet through a 180°C slit extrusion die, and then bidirectionally stretched at 270°C with a transverse stretching ratio of 1:2.5 and a longitudinal stretching ratio of 1:5, and finally rolled into a film material with a thickness of 50 μm.

[0146] S4. Preparation of polyphenylene sulfide staple fibers:

[0147] Under a vacuum degree of 0.02MPa, the polyphenylene sulfide pellets are dried at 110°C for 5h, and then the dried polyphenylene sulfide pellets are melt-extruded through a twin-screw extruder at 290°C under a pressure of 1.0MPa to obtain nascent fibers, which are then hot-stretched at 140°C with a stretch ratio of 1:4; then hot-stretched at 250°C with a stretch ratio of 1:1, and finally subjected to heat setting and slitting processes to obtain 9mm polyphenylene sulfide staple fibers.

[0148] S5. Preparation of meta-aramid staple fiber:

[0149] The polymer solution is filtered and then passed through a spinneret to coagulate in a 60% N,N-dimethylacetamide aqueous solution (coagulation bath) to form nascent fibers. After countercurrent water washing, the fibers are dried on a drying roller at 90°C. The dried fibers are heat treated in a channel at 280°C and finally cut into 20mm meta-aramid staple fibers.

[0150] S6. Preparation of meta-aramid precipitation slurry:

[0151] Water, glycerin, and chloride salt are mixed in a mass ratio of 30:60:10 to prepare a mixed liquid, and then the mixed liquid is mixed with a polymer solution in a weight ratio of 8:1 to obtain a slurry. The slurry is subjected to high-speed shearing at a speed of 7000 rpm / min for 50 minutes at a temperature of 20°C, and then cooled and formed in cold water at -10°C, and then subjected to multi-stage countercurrent washing, with the first stage at 10°C, the second stage at 30°C, the third stage at 50°C, the fourth stage at 70°C, and the fifth stage at 90°C, to obtain a meta-aramid precipitation slurry, wherein the average length of the meta-aramid precipitation fibers in the meta-aramid precipitation slurry is 1.8 mm, and the specific surface area is 25 m 2 / g.

[0152] S7. Preparation of paper materials:

[0153] First, the meta-aramid precipitated pulp is beaten and dispersed, and the polyphenylene sulfide staple fiber and the meta-aramid staple fiber are debonded and dispersed to obtain debonded mixed fibers. The mass ratio of polyphenylene sulfide staple fiber, meta-aramid staple fiber, and meta-aramid precipitated pulp is 3:2:5. Then, the precipitated pulp and the debonded mixed fibers are stirred at a speed of 2000 rpm / min for 25 minutes to obtain mixed pulp. The mixed pulp is then formed by flow conveying, pressed and dried under a pressure of 1 MPa and a temperature of 170°C, and then hot-pressed at a pressure of 20 MPa and a temperature of 230°C. Finally, the mixed paper material is obtained after rewinding and slitting.

[0154] S8. Preparation of composite materials:

[0155] Coat both sides of the membrane with 5g / m 2After gluing, it is dried in a drying tunnel at 50°C, and the two sides are pressed with paper at a pressure of 0.3MPa and 35°C to prepare a composite material, that is, an oil-resistant and hydrolysis-resistant composite material. It can be used after being placed in an environment of 25°C for 6 days to complete curing. The thickness of the composite material is 190μm.

[0156] Example 3

[0157] The preparation of an oil-resistant and hydrolysis-resistant electrical insulation composite material comprises the following specific steps:

[0158] S1. Preparation of polyphenylene sulfide pellets:

[0159] Sodium sulfide is heated at a vacuum degree of 0.1 MPa and a temperature of 85°C for 1.2 hours, then the temperature is raised to 115°C and heated for 0.6 hours. The material is cooled to 39°C to obtain dehydrated anhydrous sodium sulfide, and then the anhydrous sodium sulfide is dissolved in N-methylpyrrolidone under a nitrogen environment, and then 0.98 equivalents of dichlorobenzene (meta-dichlorobenzene and p-dichlorobenzene, the molar ratio is 4:1) are added. At a reaction pressure of 0 MPa and a polymerization temperature of 270°C, the reaction is carried out under the action of potassium carbonate for 1 hour to obtain a solid-liquid mixture. Finally, the mixture is filtered, washed with water, and dried to obtain polyphenylene sulfide pellets.

[0160] S2. Preparation of polymer solution:

[0161] m-Phenylenediamine was dissolved in N,N-dimethylacetamide to prepare a solution with a mass concentration of 8%, 90% equivalent of isophthaloyl chloride was added, and the mixture was stirred at 5°C for 20 minutes for prepolymerization. Ammonia water was added to adjust the pH to 6.9, and the prepolymer solution was obtained after filtration. The remaining 5% equivalent of isophthaloyl chloride was added to the prepolymer solution, and the mixture was reacted at 20°C for 30 minutes. Diethylamine was then added to adjust the pH to 7.5 to obtain a polymerization solution with a viscosity of 850 Po.

[0162] S3. Preparation of membrane materials:

[0163] The polyphenylene sulfide pellets were dried at 140°C for 3 hours under a vacuum degree of 0.01 MPa, and then the dried polyphenylene sulfide pellets were melt-extruded through a twin-screw extruder at 270°C and a pressure of 9.0 MPa, and formed into a sheet through a 100°C slit extrusion die, and then bidirectional stretching was completed at 130°C with a transverse stretching ratio of 1:2 and a longitudinal stretching ratio of 1:3, and finally rolled into a film material. The thickness of the film material was 55 μm.

[0164] S4. Preparation of polyphenylene sulfide staple fibers:

[0165] Under a vacuum degree of 0.01 MPa, the polyphenylene sulfide pellets are dried at 140°C for 3 hours, and then the dried polyphenylene sulfide pellets are melt-extruded through a twin-screw extruder at 330°C under a pressure of 6.0 MPa to obtain spun fibers, which are then hot-stretched at 270°C with a stretch ratio of 1:7; then hot-stretched at 320°C with a stretch ratio of 1:1.1, and finally subjected to heat setting and slitting processes to obtain 20mm polyphenylene sulfide staple fibers.

[0166] S5. Preparation of meta-aramid staple fiber:

[0167] The polymer solution is filtered and then passed through a spinneret to coagulate in a 63% N-methylpyrrolidone aqueous solution (coagulation bath) to form nascent fibers. After countercurrent water washing, the fibers are dried on a drying roller at 140°C. The dried fibers are heat treated in a channel at 330°C and finally cut into 10mm meta-aramid staple fibers.

[0168] S6. Preparation of meta-aramid precipitation slurry:

[0169] Water, glycerin, and chloride salt are mixed in a mass ratio of 50:45:5 to prepare a mixed liquid, and then the mixed liquid is mixed with a polymer solution in a weight ratio of 16:1 to obtain a slurry. The slurry is subjected to high-speed shearing at a speed of 4000 rpm / min for 10 minutes at a temperature of 60°C, and then cooled and formed in cold water at 5°C, and then subjected to multi-stage countercurrent washing, with the first stage at 20°C, the second stage at 40°C, the third stage at 60°C, the fourth stage at 80°C, and the fifth stage at 95°C, to obtain a meta-aramid precipitation slurry, wherein the average length of the meta-aramid precipitation fibers in the meta-aramid precipitation slurry is 0.6 mm, and the specific surface area is 55 m 2 / g.

[0170] S7. Preparation of paper materials:

[0171] First, the meta-aramid precipitated pulp is beaten and dispersed, and the polyphenylene sulfide staple fiber and the meta-aramid staple fiber are deflaked and dispersed to obtain deflaked mixed fibers. The mass ratio of polyphenylene sulfide staple fiber, meta-aramid staple fiber, and meta-aramid precipitated pulp is 4:3:3. Then, the precipitated pulp and the deflaked mixed fibers after beating and dispersion are stirred at a speed of 4000 rpm / min for 15 minutes to obtain mixed pulp. The mixed pulp is then formed by flow conveying, pressed and dried under a pressure of 3 MPa and a temperature of 130°C, and then hot-pressed at a pressure of 30 MPa and a temperature of 270°C. Finally, the mixed paper material is obtained after rewinding and slitting.

[0172] S8. Preparation of composite materials:

[0173] Coat both sides of the membrane with 50g / m 2After gluing, it is dried in a drying tunnel at 150°C, and the two sides are pressed with paper at a pressure of 0.6MPa and 70°C to prepare a composite material, that is, an oil-resistant and hydrolysis-resistant composite material. It can be used after being placed in an environment of 90°C for 2 days to complete curing. The thickness of the composite material is 238μm.

[0174] Comparative Example 1

[0175] Preparation of an electrical insulation composite material:

[0176] The composite material was prepared by the same method as in Example 1, except that polyphenylene sulfide staple fibers were not added during the preparation of the paper material in this comparative example 1. The specific steps were as follows:

[0177] S1. Preparation of polyphenylene sulfide pellets:

[0178] The preparation method is the same as that of Example 1.

[0179] S2. Preparation of polymer solution:

[0180] The preparation method is the same as that of Example 1.

[0181] S3. Preparation of membrane materials:

[0182] The preparation method is the same as that of Example 1.

[0183] S4. Preparation of polyphenylene sulfide staple fibers:

[0184] In this comparative example 1, there is no need to prepare polyphenylene sulfide staple fibers.

[0185] S5. Preparation of meta-aramid staple fiber:

[0186] The preparation method is the same as that of Example 1.

[0187] S6. Preparation of meta-aramid precipitation slurry:

[0188] The preparation method is the same as that of Example 1.

[0189] S7. Preparation of paper materials:

[0190] First, the meta-aramid precipitated pulp is beaten and dispersed, and the meta-aramid staple fiber is debonded and dispersed to obtain debonded staple fiber. The mass ratio of meta-aramid staple fiber and meta-aramid precipitated pulp is 7:3. Then, the precipitated pulp and debonded staple fiber after beating and dispersion are stirred at a speed of 4000rpm / min for 15min to obtain pulp. After that, the pulp is formed by flow conveying, pressed and dried under the conditions of pressure 3MPa and temperature 130℃, and then hot pressed under the conditions of pressure 30MPa and temperature 270℃. Finally, the paper material is obtained after rewinding and slitting.

[0191] S8. Preparation of composite materials:

[0192] The preparation method is the same as that of Example 1.

[0193] Comparative Example 2

[0194] Preparation of an electrical insulation composite material:

[0195] The composite material was prepared by the same method as in Example 1, except that when preparing polyphenylene sulfide pellets in Comparative Example 2, only m-dichlorobenzene was used as dichlorobenzene, and p-dichlorobenzene was not added. Other preparation methods were the same as in Example 1.

[0196] Comparative Example 3

[0197] Preparation of an electrical insulation composite material:

[0198] The composite material was prepared by the same method as in Example 1, except that: when preparing polyphenylene sulfide pellets in this comparative example 3, the amount of p-dichlorobenzene was increased, and the molar ratio of intermediate dichlorobenzene to ground dichlorobenzene in this comparative example 3 was 1:1. The other preparation methods were the same as in Example 1.

[0199] Comparative Example 4

[0200] Preparation of an electrical insulation composite material:

[0201] The composite material was prepared by the same method as in Example 1, except that: in the paper preparation process in step S7 of this comparative example 4, the usage ratio of polyphenylene sulfide staple fiber was increased, and the mass ratio of polyphenylene sulfide staple fiber, meta-aramid staple fiber, and meta-aramid precipitation slurry in this comparative example 4 was 5:2:3. The other preparation methods were the same as in Example 1.

[0202] Comparative Example 5

[0203] Preparation of an electrical insulation composite material:

[0204] The composite material was prepared by the same method as in Example 1, except that the pressure of the hot pressing molding was reduced in step S7 of this comparative example 5. The pressure of the hot pressing molding in this comparative example 5 was 12 MPa.

[0205] Comparative Example 6

[0206] Preparation of an electrical insulation composite material:

[0207] The composite material was prepared by the same method as in Example 1, except that in step S8 of this comparative example 6, the pressing temperature was lowered, and the pressing temperature in this comparative example 6 was 15°C.

[0208] The composite materials prepared in the above examples and comparative examples were subjected to performance tests, wherein the test methods involved are as follows.

[0209] Oil and hydrolysis resistance test method: The ATF oil used is Castrol BOT383, 0.2%~0.5% volume of deionized water is added, and then shear stirring is carried out at a speed of 8000r / min for 5 minutes to fully mix the oil and water; test temperature: 25℃→(155℃ / 40h~-45℃ / 8h)×8 cycles→25℃, heating from 25℃ to 155℃, the heating rate is about 3℃ / min, during the test, 155℃ and -45℃ are directly switched by warm impulse, and the switching time is less than 30s (two-box method, sample conversion outside the box).

[0210] The testing standards involved are:

[0211] GB / T 5591.2-2017 Flexible composite materials for electrical insulation Part 2: Test methods;

[0212] GB / T 20629.2-2013 “Non-cellulose paper for electrical purposes Part 2: Test methods”;

[0213] GB / T 7354-2018 High voltage test technique - Partial discharge measurement.

[0214] The changes in material performance indicators of the composite materials before and after 8 cycles of oil resistance and hydrolysis resistance testing are shown in Tables 1 to 3 below.

[0215] Table 1 Data on the oil-resistant and hydrolysis-resistant performance index retention rates of the composite materials of Examples 1-3 and Comparative Examples 1-2

[0216]

[0217] Note: The "conventional oil- and water-resistant products" in Table 1 above refer to: 50μm pure aramid paper is compounded with PI film, and LA2681 and LA5094 are used as compound glue to prepare a composite material product with a thickness of 210μm. Pure aramid paper refers to Minshida YT564-0.05, without any other fibers.

[0218] In addition, during the oil and hydrolysis resistance test, the composite materials of Comparative Examples 3, 4, 5, and 6 all failed the oil and hydrolysis resistance test and showed delamination and blistering.

[0219] Table 2 Performance index data of composite materials of Examples 1-3 and Comparative Examples 1-2

[0220]

[0221] Table 3 Performance index data of composite materials of comparative examples 3-6

[0222]

[0223] The performance index retention rates before and after the oil and hydrolysis resistance tests show that the composite materials prepared using the preparation methods described in Examples 1-3 exhibit excellent oil and hydrolysis resistance. Compared to conventional oil and hydrolysis-resistant products, the composite materials prepared using the present invention exhibit higher retention rates. This indicates that after eight cycles of oil and hydrolysis resistance testing, the composite materials still maintain excellent mechanical and electrical insulation properties, effectively extending the composite material's service life in the motor. Furthermore, the composite materials possess suitable strength properties, further facilitating installation within the motor.

[0224] Comparing the experimental results of Comparative Example 1 and Example 1, it can be seen that if polyphenylene sulfide staple fibers are not added during paper production, the mechanical properties of the composite material, such as stiffness, are significantly lower than those of the composite material prepared using the present invention. After oil and hydrolysis resistance testing, the performance retention rate also significantly decreases. This demonstrates that the addition of polyphenylene sulfide fibers to paper can effectively enhance the protective effect of the outer paper on the inner film, improving the oil and water resistance of the overall material. Furthermore, the addition of polyphenylene sulfide fibers can effectively improve the performance indicators of the paper, further demonstrating that the paper and film materials used in the preparation method described herein work together to produce a composite material with excellent performance and durability.

[0225] Comparing the experimental results of Comparative Example 2 and Example 1 reveals that when only m-dichlorobenzene is used as the dichlorobenzene in the preparation of polyphenylene sulfide pellets, without adding p-dichlorobenzene, the stiffness of the resulting composite material decreases significantly. This can easily cause paper jams in the slots during actual production, impacting production efficiency. Furthermore, during oil and hydrolysis resistance testing, the retention rate of the sample prepared in Comparative Example 2 is significantly lower than that of Example 1, but significantly higher than that of Comparative Example 1 and conventional oil- and water-resistant products, demonstrating that the introduction of sulfide functional groups has a certain effect on oil and hydrolysis resistance.

[0226] Comparing the experimental results of Comparative Example 3 and Example 1, it can be seen that increasing the proportion of p-dichlorobenzene used in preparing polyphenylene sulfide pellets increases the strength of the produced fibers. However, this can easily cause fluffing on the paper surface during subsequent papermaking, weakening the protective effect of the outer paper on the inner insulating film. Furthermore, the increased use of p-dichlorobenzene increases the rigidity of the overall material, making it prone to brittle cracking during the slot bending process, increasing the defective rate of motor products. Therefore, using the specified ratio of m-dichlorobenzene to p-dichlorobenzene used in the present invention to prepare polyphenylene sulfide pellets, the resulting composite material has more suitable strength properties and is more suitable for use in motors.

[0227] From the comparison of the experimental results of Comparative Example 4 and Example 1, it can be seen that if the proportion of polyphenylene sulfide staple fibers is increased during the paper preparation process, it is easy to cause difficulties in hot pressing the paper, the paper surface becomes fuzzy, the bonding is not strong, and the product is prone to delamination, which also weakens the protective effect of the outer paper on the inner insulating film material.

[0228] Comparing the experimental results of Comparative Example 5 and Example 1 shows that if the hot pressing pressure is reduced during paper preparation, the paper will easily become fuzzy, resulting in weak glue adhesion and delamination. This ultimately reduces the strength of the composite material and weakens the protective effect of the outer paper on the inner insulating film. In the preparation method described in the present invention, the addition of polyphenylene sulfide staple fibers during paper preparation, combined with higher hot pressing pressure, further facilitates the production of a composite material with excellent performance.

[0229] From the comparison of the experimental results of Comparative Example 6 and Example 1, it can be seen that if the pressing temperature is lowered during the preparation of the composite material, the film and paper will not be fully bonded, resulting in delamination of the composite material. In the preparation method of the present invention, appropriate heating during the pressing process is conducive to fully bonding the film and paper, enhancing the protective effect of the paper and glue on the film, thereby obtaining a composite material with excellent comprehensive performance.

[0230] The technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0231] For those skilled in the art, several variations and improvements may be made without departing from the scope of the present invention, which all fall within the scope of protection of the present invention. The scope of protection of the present invention shall be based on the appended claims.

Claims

1. An oil-resistant and hydrolysis-resistant electrical insulation composite material, comprising a film material, paper materials adhered to both sides of the film material, and glue for bonding, characterized in that: The membrane material is made of polyphenylene sulfide, and the pulp used to prepare the paper material includes polyphenylene sulfide staple fibers, meta-aramid staple fibers and meta-aramid precipitation slurry; The polyphenylene sulfide is prepared by polymerization of anhydrous sodium sulfide and dichlorobenzene, wherein the dichlorobenzene includes m-dichlorobenzene and p-dichlorobenzene, and the molar ratio of m-dichlorobenzene to p-dichlorobenzene is (3-4):1; In the pulp, the mass ratio of the polyphenylene sulfide staple fiber, the meta-aramid staple fiber and the meta-aramid precipitated pulp is (3-4): (2-3): (3-5); when preparing the paper material, the hot pressing pressure is 20-30 MPa and the temperature is 230-270°C; When preparing the composite material, glue is coated on both sides of the film material, dried, pressed with paper material, and cured to obtain the composite material; the pressing pressure is 0.3-0.6Mpa, and the pressing temperature is 35-70°C.

2. The oil-resistant and hydrolysis-resistant electrical insulation composite material according to claim 1, characterized in that: The molar ratio of the anhydrous sodium sulfide to dichlorobenzene is 1:(0.95-0.98).

3. The oil-resistant and hydrolysis-resistant electrical insulation composite material according to claim 1, characterized in that: The length of the polyphenylene sulfide staple fiber is 9-20 mm; the length of the meta-aramid staple fiber is 9-20 mm; the solid content of the meta-aramid fibrils in the meta-aramid precipitation slurry is 4-7%, the average length of the meta-aramid fibrils is 0.6-1.8 mm, and the specific surface area of the meta-aramid fibrils is 25-55 m 2 / g.

4. A method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material according to any one of claims 1 to 3, characterized in that: The preparation method is: S1. Preparation of polyphenylene sulfide pellets: Under inert gas conditions, dichlorobenzene and anhydrous sodium sulfide are dissolved in a polar solvent, and a polymerization reaction is carried out under the action of an alkali metal salt. After the reaction is completed, polyphenylene sulfide pellets are obtained through post-treatment. S2. Preparation of film and paper materials: Film preparation: Polyphenylene sulfide pellets are melt-extruded into sheets, and then biaxially drawn and wound to obtain film; Paper material preparation: polyphenylene sulfide pellets are melted into filaments to obtain polyphenylene sulfide staple fibers, and polyphenylene sulfide staple fibers, meta-aramid staple fibers and meta-aramid precipitated slurry are mixed and then papered to obtain paper material; S3. Preparation of composite materials: Glue is applied on both sides of the membrane material, dried, pressed with paper material, and cured to obtain a composite material.

5. The method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material according to claim 4, characterized in that: In step S1, the polymerization reaction temperature is 180-270° C., the reaction pressure is 0-2 MPa, and the reaction time is 1-2 h.

6. The method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material according to claim 4, characterized in that: The process of preparing the membrane material in step S2 is as follows: The dried polyphenylene sulfide pellets are melted at high temperature and then extruded through a twin-screw extruder through a die to form a sheet, which is then bidirectionally drawn and wound to obtain a film. The high temperature melting temperature is 270-320°C, and the extrusion pressure is 3.0-9.0 MPa; The die is a slot extrusion die, the die holding time is 4-10 hours, and the die temperature is 100-180°C; The drawing temperature is 130-270℃, the transverse drawing ratio is 1:(2-2.5), and the longitudinal drawing ratio is 1:(3-5).

7. The method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material according to claim 4, characterized in that: The process of preparing the paper material in step S2 is as follows: First, the meta-aramid precipitated pulp is beaten and dispersed, and the polyphenylene sulfide staple fiber and the meta-aramid staple fiber are debonded and dispersed to obtain debonded mixed fibers. Then, the precipitated pulp after beating and dispersion and the debonded mixed fibers are stirred and blended uniformly to obtain mixed pulp. The mixed pulp is subjected to flow forming, pressing and drying, hot pressing forming, and rewinding and slitting to obtain paper material. The pressure of the pressing and drying is 1-3 MPa, and the temperature of the pressing and drying is 130-170°C.

8. The method for preparing an oil-resistant and hydrolysis-resistant electrical insulating composite material according to claim 4, characterized in that: In step S3, the amount of glue applied on one side of the membrane is 5-50 g / m 2 , the drying temperature is 50-150℃.

9. Use of the oil-resistant and hydrolysis-resistant electrical insulation composite material according to any one of claims 1 to 3, characterized in that: The composite material is used in a motor.

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