Method for preparing pure polyphenylene sulfide-based fiber cloth prepreg sheet stock, composite board and preparation method and application of composite board

Abstract

The invention relates to a method for preparing a pure polyphenylene sulfide-based fiber cloth prepreg sheet stock, a composite board, and a preparation method and application of the composite board. The preparation method of the prepreg sheet material comprises the following steps: crushing polyphenylene sulfide, and screening to obtain PPS powder; mixing the PPS powder with a low-temperature degreasing bonding component and an auxiliary agent to obtain a blended rubber material; coating two sides of the blended rubber material on the surface of reinforced fiber cloth, and compacting to form a pre-impregnated sheet material; and the laminated prepreg sheets are subjected to thermal lamination to form the pure polyphenylene sulfide-based fiber cloth composite board. The solvent-free high-efficiency hot coating and dipping process of the polyphenylene sulfide base material on the fiber cloth is realized by adopting a low-temperature degreasing bonding component capable of thermal flowing, the high-performance and recyclable pure polyphenylene sulfide-based fiber cloth composite board can be produced, and the fiber cloth composite board can be widely applied to parts such as new energy automobile battery covers, automobile overall chassis or aerospace structural parts and the like.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a method for preparing pure polyphenylene sulfide-based fiber cloth prepreg, composite board, its preparation method and application. Background Technology

[0002] Thermoplastic composites, with their advantages of recyclability, high damage tolerance, and short-cycle molding, are gradually replacing traditional thermosetting composites in fields such as aerospace, new energy vehicles, and electronic packaging. The global thermoplastic composites market is projected to exceed $15 billion by 2025, with fiber-reinforced high-performance thermoplastic composites accounting for over 30%. Compared to thermosetting materials, thermoplastic composites can be recycled through melt-and-reshape processes, aligning with the green manufacturing requirements under the "dual-carbon" strategy.

[0003] Polyphenylene sulfide (PPS), a semi-crystalline thermoplastic engineering plastic, possesses excellent thermal stability, chemical corrosion resistance, and low moisture absorption, making it an ideal matrix for preparing lightweight, high-strength composite materials. Furthermore, as a thermoplastic resin, PPS can be 100% recycled through melt processing, avoiding the environmental pollution problems associated with thermosetting composites. PPS / carbon fiber composites have a specific strength more than three times that of aluminum alloys and exhibit excellent fatigue resistance. Despite the superior performance of PPS-based composites, production limitations mean that currently only the German company Ensinger has achieved commercial production of high-quality products. Their products are widely used in high-performance load-bearing components in aerospace and other fields in many countries, and COMAC in my country has already applied them to wing components. Demand for this product is gradually increasing, with Ensinger's 4mm thick product already priced at 15,000 RMB per square meter, making it imperative to accelerate the domestic substitution process for this product.

[0004] Its industrial application is still limited by the following core issues.

[0005] Currently, melt impregnation is the most mature process developed by manufacturers and researchers for PPS-based prepregs. However, PPS melt viscosity is high, making it difficult to fully impregnate the woven fabric during traditional melt impregnation, resulting in high internal porosity and poor interlayer bonding in the composite material. Existing technologies use high-temperature and high-pressure impregnation, which can partially improve the situation, but it easily causes PPS to yellow due to thermal oxidation, and the process consumes a lot of energy and requires sophisticated equipment.

[0006] In addition to melt impregnation, the powder impregnation process, which involves adding a mobile phase binder, uses the binder phase as an alloy in the final molding application of the material. This process cannot produce pure polyphenylene sulfide composites, resulting in a decline in the corrosion resistance, mechanical properties, and other advantageous properties of PPS. Summary of the Invention

[0007] In view of this, a method for preparing pure polyphenylene sulfide-based fiber cloth prepreg, composite board, preparation method and application is provided, which is solvent-free, low energy consumption, high density, high mechanical properties and recyclable. By using a heat-flowable low-temperature degreasing adhesive component, a solvent-free and efficient hot coating impregnation process of polyphenylene sulfide substrate onto fiber cloth is achieved, which can produce high-performance pure PPS-based fiber cloth composite board.

[0008] A method for preparing pure polyphenylene sulfide-based fiber prepreg sheets includes the following steps: A1) Powdering of polyphenylene sulfide; Powdered polyphenylene sulfide resin particles are pulverized into fine powder through a pulverizing process, and the pulverized powder is then sieved into PPS powder of a predetermined particle size by a sieve. A2) Preparation of compounded rubber; PPS powder, low-temperature degreased adhesive component, and additives are added to a mixing device and mixed for a predetermined time within a predetermined temperature range to obtain a polyphenylene sulfide blended rubber. The predetermined temperature range is lower than the thermal degradation temperature or vaporization temperature of the low-temperature degreased adhesive component. The low-temperature degreased adhesive component has a degreasing temperature of less than 270°C, a solid residue of less than 3 wt% after degreasing, and maintains fluidity and adhesion at 50°C to 200°C. A3) Hot-coating prepreg of fiber cloth; the reinforcing fiber cloth is passed through the hot coating head of the multi-layer hot melt coating equipment via a traction system, and the blended adhesive obtained in step A2) is conveyed to the hot coating head via the hot melt coating equipment; then it is compacted by the rolling equipment at a predetermined pressure roller temperature, so that the adhesive penetrates into the gaps between the fiber bundles to form a prepreg sheet. The coating temperature range in this step is 80-200℃, and the predetermined pressure roller temperature range is 70-150℃.

[0009] Preferably, the volume ratio of the polyphenylene sulfide powder to the low-temperature degreasing binder is 60-80%: 20-40%.

[0010] Preferably, the low-temperature degreasing adhesive component is one or a combination of two or more of the following: paraffin-based adhesive, polyoxymethylene-based adhesive, moisture-curing reactive polyurethane hot melt adhesive, and polyvinylpyrrolidone-based adhesive; or it is one of the following: paraffin / stearic acid composite adhesive and polyoxymethylene-based adhesive. The paraffin-based adhesive may be a low-temperature degreasing adhesive compounded from paraffin or polyethylene wax, polyethylene glycol, stearic acid, and low-density polyethylene.

[0011] Preferably, the reinforcing fiber cloth is at least one of carbon fiber cloth, glass fiber cloth, basalt fiber cloth, aramid fiber cloth, poly(p-phenylenebenzodioxazole) fiber cloth, poly(aramiddioxazole) fiber cloth, and ultra-high molecular weight polyethylene fiber cloth.

[0012] Preferably, the compound material in step A2) further includes a filler component, the mass of which is 0-20% of the sum of the mass of polyphenylene sulfide powder and the low-temperature degreasing binder component; the filler component is one or a mixture of two or more of the following: carbon black, carbon fiber short filaments, carbon nanotubes, silicon dioxide, zirconium dioxide, boron nitride, silicon nitride, boron carbide, silicon carbide, talc, alumina, calcium carbonate, etc.

[0013] Preferably, the additive is one or more of the following: compatibilizer, lubricant, antioxidant, and plasticizer; the mass of the additive is 0.5-5% of the total mass of the blended rubber compound; the volume ratio of the polyphenylene sulfide powder to the low-temperature degreased colloid is 65-75% : 25-35%; the pulverization process in step A1) is to pulverize the polyphenylene sulfide resin particles using a cryogenic airflow pulverizer, with cold nitrogen gas introduced to control the temperature during the pulverization process; the mixing process is an internal mixing process, in which the PPS powder and the low-temperature degreased binder are fully mixed through the high shear force and kneading action within a closed cavity.

[0014] Preferably, the pulverization process in step A1) is one of mechanical pulverization and cryogenic pulverization; the D50 of the PPS powder after sieving is 5-50 μm; the mixing process in step A2) can be one of internal mixing, open milling, and continuous screw extrusion; the predetermined temperature range in step A2) is 80-200℃.

[0015] A method for preparing a pure polyphenylene sulfide-based fiber cloth composite board includes the following steps: B1) Cutting and stacking of prepreg sheets; a method for preparing pure polyphenylene sulfide-based fiber cloth prepreg sheets according to any one of claims 1-7 is used to obtain prepreg sheets, the prepreg sheets are cut into sizes corresponding to hot press molds by cutting equipment, and the prepreg sheets are stacked in 2-20 layers after cutting. B2) Preheating and lamination: The prepreg sheets are laid in layers and placed in a hot lamination mold. The lamination equipment temperature is raised to 150~230℃, preheated at 0.5~2MPa pressure for 1~30min, and then hot-pressed at 2~15MPa pressure for 10~180min to obtain a preliminary laminate bonded by low-temperature degreasing adhesive components. B3) Low-temperature degreasing; the preliminary laminate is placed in a degreasing oven and degreased at 100~250℃ for 1~10 hours; B4) Hot lamination molding; the laminated board after low-temperature degreasing is placed in a hot lamination mold, the lamination equipment temperature is raised to 270~350℃, and the preheating is carried out at 0.5~2MPa pressure for 1~60min, followed by hot pressing, and the pressure is held at 2~25MPa for 10~600min. B5) Cooling and de-temperatureing: Maintain the molding pressure while cooling down to below 150°C, then open the mold to obtain a pure polyphenylene sulfide-based fiber cloth composite board.

[0016] A pure polyphenylene sulfide-based fiber cloth composite board comprises multilayer prepreg sheets formed by hot lamination after lamination. The hot lamination method involves laminating multiple layers of prepreg sheets prepared according to any one of claims 1-7 and then hot-pressing them. The hot-pressing conditions are as follows: preheating at 270~350℃ and 0.5~2MPa pressure for 1~60 min, followed by hot pressing, and holding at 2~25MPa pressure for 10~600 min; further preheating and low-temperature degreasing are performed before hot pressing.

[0017] Furthermore, a fiber cloth composite board based on the above-mentioned pure polyphenylene sulfide is also provided for application in new energy vehicle battery covers, automobile chassis, and aerospace structural components.

[0018] The above-mentioned method for preparing pure polyphenylene sulfide-based fiber cloth prepreg sheets, composite boards, and their preparation methods have at least the following beneficial effects: By pulverizing PPS resin into powder and dispersing it in a low-temperature degreasing binder component, the mixed colloid is then subjected to solvent-free hot coating impregnation of the fiber cloth at a certain temperature to obtain a prepreg. A pure polyphenylene sulfide-based fiber cloth composite board is then prepared through a subsequent lamination and hot pressing process. This product utilizes a heat-flowable low-temperature degreasing binder component to achieve a solvent-free, efficient hot coating impregnation process of polyphenylene sulfide substrate onto fiber cloth, enabling the production of high-performance pure PPS-based fiber cloth composite boards. Unlike the currently predominantly used thermosetting composite boards, this is a thermoplastic recyclable material, which does not conflict with existing environmental policies in my country and the EU. It is a high-performance, environmentally friendly alternative to existing new energy vehicle chassis, ship and high-speed rail transportation components, and aerospace structural components. Furthermore, the above-mentioned pure polyphenylene sulfide-based fiber cloth prepreg sheets and composite boards also have the following advantages: a1. This application's technical solution creatively introduces a low-temperature degreasing binder as the loading matrix for polyphenylene sulfide (PPS) powder. This medium can achieve a low-temperature degreasing process while completely preserving the inherent properties of PPS resin and reinforcing fiber fabric, realizing a solvent-free hot-coating molding process system. High-performance composite materials can be obtained after subsequent low-temperature degreasing and lamination curing processes. Compared to the limitations of traditional melt impregnation methods due to the extremely high viscosity of PPS melt and reliance on high-specification equipment, this preparation technology exhibits significant advantages. For example, the process system equipment configuration is simplified, the energy efficiency of the production process is improved by more than 30%, and the resulting composite material has high interfacial bonding strength, with performance comparable to foreign melt impregnation method products, meeting the high load-bearing requirements of high-performance structural components in the aerospace field. a2. The technical solution of this application adopts a solvent-free thermal coating process, which completely avoids the problems of solvent use and residue. The VOC emission is close to zero, which meets the green manufacturing standards and has significant advantages in terms of environmental protection and production safety. a3. Compared with mature thermosetting composite materials such as sheet molding compound (SMC) boards and epoxy fiberglass boards, the composite board prepared in this application has significant advantages. For example, it has a high proportion of thermoplastic components, which can not only be efficiently recycled by adding plastic substrates after crushing and melting, but also has better mechanical properties. It is a high-performance, recyclable thermoplastic composite material. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process for making a composite board from pure polyphenylene sulfide-based fiber cloth prepreg sheet, as provided in an embodiment of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0021] Please see Figure 1 This paper illustrates a process for preparing a pure polyphenylene sulfide-based fiber cloth composite board. The method first prepares a pure polyphenylene sulfide-based fiber cloth prepreg, and includes the following steps: A1) Powdering of polyphenylene sulfide; Powdered polyphenylene sulfide resin particles are pulverized into fine powder through a pulverizing process, and the pulverized powder is then sieved into PPS powder of a predetermined particle size by a sieve. Preparation of compounded rubber: PPS powder, low-temperature degreased adhesive component, and additives are added to a mixing device and mixed for a predetermined time within a predetermined temperature range to obtain a polyphenylene sulfide blended rubber. The predetermined temperature range is lower than the thermal degradation temperature or vaporization temperature of the low-temperature degreased adhesive component. The low-temperature degreased adhesive component has a degreasing temperature of less than 270°C, a solid residue of less than 3 wt% after degreasing, and maintains fluidity and adhesion at 50°C to 200°C. A3) Hot-coating prepreg of fiber cloth; the reinforcing fiber cloth is passed through the hot coating head of the multi-layer hot melt coating equipment via a traction system, and the blended adhesive obtained in step A2) is conveyed to the hot coating head via the hot melt coating equipment; then it is compacted by the rolling equipment at a predetermined pressure roller temperature, so that the adhesive penetrates into the gaps between the fiber bundles to form a prepreg sheet. The coating temperature range in this step is 80-200℃, and the predetermined pressure roller temperature range is 70-150℃.

[0022] The method of this invention primarily addresses the systemic defects existing in the preparation of pure polyphenylene sulfide (PPS)-based fiber prepreg sheets using existing melt impregnation and powder impregnation methods. These defects include: uneven fiber impregnation due to the high viscosity of the PPS melt; poor environmental friendliness, residual micropores, and uneven powder dispersion in wet processes due to solvent dependence; poor powder flowability, insufficient fiber penetration depth, and fiber damage and matrix aging caused by high temperature and pressure in dry processes; and common bottlenecks faced by powder impregnation methods, such as weak interfacial bonding (dominated by physical adsorption), high process complexity, and limited matrix toughening. Therefore, this invention provides a solvent-free, low-energy-consumption preparation method. Through the synergistic effect of an innovative thermal coating process and easily degreased adhesive components, it solves key technical problems in existing PPS composite board processes, such as uneven fiber impregnation due to high melt viscosity, porosity defects caused by solvent residue, and low interfacial bonding strength. Ultimately, it yields high-density, high-mechanical-performance, and recyclable high-performance PPS-based fiber composite sheets.

[0023] The pulverization process described in step A1) is one of mechanical pulverization or cryogenic pulverization. More preferably, a cryogenic airflow pulverizer is used to pulverize the PPS resin particles, with cold nitrogen gas introduced during the pulverization process to control the temperature. The D50 of the sieved PPS powder described in step A1) is preferably 5~50 μm.

[0024] Preferably, the volume ratio of polyphenylene sulfide powder to the low-temperature degreased binder component in step A2) is 60-80% : 20-40%, and the mass ratio is calculated based on the volume ratio. The mass of the filler component is 0-20% of the sum of the masses of the polyphenylene sulfide powder and the low-temperature degreased binder component, and the mass of the additive is 0.5-5% of the total mass of the blended rubber compound. More preferably, the volume ratio of polyphenylene sulfide powder to the low-temperature degreased colloid is 65-75% : 25-35%. Within this volume ratio range, the rubber compound maintains good flowability and adhesion during mixing and hot coating, while ensuring sufficient coverage density of the polyphenylene sulfide powder.

[0025] Preferably, the low-temperature degreasing adhesive component in step A2) is one or a combination of two or more of the following: paraffin-based adhesive, polyoxymethylene-based adhesive, moisture-curing reactive polyurethane hot melt adhesive, and polyvinylpyrrolidone-based adhesive; or it is one of the following: a paraffin / stearic acid composite adhesive and a polyoxymethylene-based adhesive. More preferably, the low-temperature degreasing adhesive component is one of the following: a paraffin / stearic acid composite adhesive and a polyoxymethylene-based adhesive. The paraffin-based adhesive can be a compound low-temperature degreasing adhesive of paraffin or polyethylene wax, polyethylene glycol, stearic acid, and low-density polyethylene, which has good processability and is easy to degrease. The polyoxymethylene-based adhesive can achieve low-temperature degreasing at 130~150℃ through oxalic acid catalysis. The oxalic acid and the decomposed formaldehyde gas, when burned, produce no environmentally polluting components, making it green and environmentally friendly. Through experiments, we found that if degreasing is not performed or is insufficient, it will affect the mechanical properties of the product and cause defects.

[0026] Preferably, the compound material in step A2) further includes a filler component, the mass of which is 0-20% of the sum of the mass of polyphenylene sulfide powder and the low-temperature degreasing binder component; the filler component may be, but is not limited to, one or a mixture of two or more of the following: carbon black, carbon fiber short filaments, carbon nanotubes, silicon dioxide, zirconium dioxide, boron nitride, silicon nitride, boron carbide, silicon carbide, talc, alumina, calcium carbonate, etc.

[0027] The additives in step A2) are preferably one or more of the following: compatibilizer, lubricant, antioxidant, and plasticizer. More preferably, the additives are a mixture of compatibilizer, lubricant, and plasticizer. The compatibilizer is a silane coupling agent, titanate coupling agent, or maleic anhydride grafted compound; the lubricant is a stearic acid compound; and the plasticizer is polyethylene glycol. The mass of the additives is 0.5-5% of the total mass of the blended rubber compound. The mixing process in step A2) can be one of internal mixing, open milling, or continuous screw extrusion; the predetermined temperature range in step A2) is 80-200℃. The mixing process is preferably an internal mixing process, where the PPS powder and the low-temperature degreased binder are fully mixed through high shear force and kneading action within a closed cavity.

[0028] Preferably, the reinforcing fiber cloth is at least one selected from carbon fiber cloth, glass fiber cloth, basalt fiber cloth, aramid fiber cloth, poly(p-phenylenebenzodioxazole) fiber cloth, poly(aramiddioxazole) fiber cloth, and ultra-high molecular weight polyethylene fiber cloth. More preferably, carbon fiber woven cloth is used, as the material as a whole has a higher modulus and lower density for application in high-performance lightweight structural components.

[0029] This embodiment describes a method for preparing a pure polyphenylene sulfide-based fiber cloth composite board, which includes the following steps.

[0030] B1) Cutting and stacking of prepreg sheets; obtain prepreg sheets according to the method for preparing pure polyphenylene sulfide-based fiber cloth prepreg sheets as described above, cut the prepreg sheets into sizes corresponding to the hot press mold using a cutting device, and stack the prepreg sheets in 2-20 layers after cutting; the total thickness after stacking does not exceed 2mm.

[0031] B2) Preheating and lamination: After the prepreg sheets are laid in layers, they are placed in a hot lamination mold. The lamination equipment temperature is raised to 150~230℃, and the preheating is carried out at 0.5~2MPa pressure for 1~30min. Then, hot pressing is carried out at 2~15MPa pressure for 10~180min to obtain a preliminary laminate bonded by low-temperature degreasing adhesive components.

[0032] B3) Low-temperature degreasing; the preliminary laminate is placed in a degreasing furnace and degreased at 100~250℃ for 1~10 hours. Preferably, the low-temperature degreasing in step B3) is carried out in one of a reaction atmosphere, a protective atmosphere, or a vacuum environment. The reaction atmosphere is a reactive atmosphere such as oxygen or oxalic acid gas, which is conducive to the low-temperature degreasing of different binders; the protective atmosphere is an inert gas atmosphere such as nitrogen, argon, or neon. More preferably, when a compound paraffin-based binder is used, oxygen-nitrogen staged degreasing can be used, and the low-density polyethylene in the wax-based component has better thermal degradation properties in an aerobic environment; when a polyoxymethylene-based binder is used, low-temperature environmentally friendly degreasing can be carried out using an oxalic acid degreasing furnace, and the exhaust gas after degreasing is post-treated to generate water, carbon dioxide, and other environmentally harmless gases.

[0033] B4) Hot lamination molding: The laminated board after low-temperature degreasing is placed in a hot lamination mold. The lamination equipment temperature is raised to 270~350℃, and the preheating is carried out at 0.5~2MPa pressure for 1~60min. Then, the hot pressing is carried out at 2~25MPa pressure for 10~600min.

[0034] B5) Cooling and de-temperature reduction; maintain molding pressure while cooling down to below 150°C, then open the mold to obtain a pure polyphenylene sulfide-based fiber cloth composite board. Preferably, the pure polyphenylene sulfide-based fiber cloth composite board product obtained by hot lamination in step B4) can be further processed through molding, vacuum forming, and other processes to obtain high-performance, environmentally friendly, and recyclable products for use in new energy vehicle battery covers, automotive chassis, and aerospace structural components.

[0035] Another aspect of this invention provides a pure polyphenylene sulfide-based fiber cloth composite board, comprising multiple layers of prepreg sheets formed by hot lamination. The hot lamination method involves stacking multiple layers of prepreg sheets prepared according to the above method and then hot-pressing them. The hot-pressing conditions are as follows: preheating at 270-350°C and 0.5-2 MPa for 1-60 minutes, followed by hot pressing and holding at 2-25 MPa for 10-600 minutes. Prior to hot pressing, further preheating and low-temperature degreasing are performed. The preheating and low-temperature degreasing are performed using the steps and process conditions described above, and will not be repeated here.

[0036] Furthermore, another aspect of this invention provides a fiber cloth composite board based on the aforementioned pure polyphenylene sulfide (PPS) for use in new energy vehicle battery covers, automotive chassis, and aerospace structural components. That is, as described above, the PPS-based fiber cloth composite board product heat-laminated in step B4) can be further processed through molding, vacuum forming, and other processes to obtain high-performance, environmentally friendly, and recyclable products for new energy vehicle battery covers, automotive chassis, and aerospace structural components.

[0037] The following examples illustrate the preparation methods of pure polyphenylene sulfide-based fiber prepreg sheets and composite boards, as well as the performance test results of the prepreg sheets.

[0038] Example 1 PPS resin particles were pulverized using a cryogenic airflow pulverizer, with cold nitrogen gas introduced to control the temperature. The pulverized powder was then sieved through a sieve to separate fine powder with a particle size of less than 15 μm for later use.

[0039] 3111g of PPS powder, 737.8g of paraffin wax, 89g of low-density polyethylene, 17.8g of polyethylene glycol, 44.5g of stearic acid, and 20g of silane coupling agent KH550 were added to a mixing equipment and mixed for 30 minutes at 160℃, top bolt pressure of 0.5MPa, and rotation speed of 30rpm to obtain polyphenylene sulfide rubber compound.

[0040] 0.2mm thick T700 grade carbon fiber plain weave fabric is passed through the hot-coating die head of a multi-layer hot-melt coating equipment via a traction system. The barrel temperature of the hot-coating equipment is raised to 180℃, and the blended adhesive is conveyed to the hot-coating die head through a screw-driven hot-melt coating equipment, coating both sides of the carbon fiber woven fabric. Subsequently, it is compacted through a three-roll mill to obtain a 0.32mm thick polyphenylene sulfide prepreg, with the pressure roller temperature at 80℃.

[0041] Polyphenylene sulfide (PPS) prepreg sheets were cut to sizes suitable for hot pressing molds using a cutting device. Four layers of the prepreg sheets were then stacked and placed in a hot lamination mold. The lamination equipment temperature was raised to 160°C, and preheating was performed at 0.5 MPa pressure for 10 minutes, followed by hot pressing at 10 MPa pressure for 60 minutes to obtain a 1.2 mm thick preliminary laminate bonded only by a low-temperature degreasing adhesive component. The preliminary laminate was then placed in a degreasing oven and degreased at 250°C in air for 2 hours, followed by degreasing under nitrogen atmosphere for 8 hours. After degreasing, four preliminary laminates were placed in a hot lamination mold. The lamination equipment temperature was raised to 290°C, and preheating was performed at 0.5 MPa pressure for 15 minutes, followed by hot pressing at 15 MPa pressure for 180 minutes. The molding pressure was maintained while cooling down to below 150°C, after which the mold was opened to obtain a pure PPS-based fiber cloth composite board with a thickness of 4.2 mm.

[0042] Example 2 The pulverization steps for polyphenylene sulfide and the mixing steps for the rubber compound are the same as in Example 1.

[0043] A 0.6mm thick S-glass fiber plain weave fabric is passed through the hot-coating die head of a multi-layer hot-melt coating equipment via a traction system. The barrel temperature of the hot-coating equipment is raised to 180℃, and the blended adhesive is conveyed to the hot-coating die head through a screw-driven hot-melt coating device, where it is coated on both sides of the carbon fiber woven fabric. Subsequently, it is compacted through a three-roll mill to obtain a 0.15mm thick polyphenylene sulfide prepreg, with the pressure roller temperature at 80℃.

[0044] Polyphenylene sulfide (PPS) prepreg sheets were cut to sizes suitable for hot pressing molds using a cutting device. Ten layers of the prepreg sheets were then stacked and placed in a hot lamination mold. The lamination equipment temperature was raised to 160°C, and preheating was performed at 0.5 MPa pressure for 10 minutes, followed by hot pressing at 10 MPa pressure for 60 minutes to obtain a 1.3 mm thick preliminary laminate bonded only by a low-temperature degreasing adhesive component. The preliminary laminate was then placed in a degreasing oven and degreased at 250°C in air for 2 hours, followed by degreasing under nitrogen atmosphere for 8 hours. After degreasing, three preliminary laminates were placed in a hot lamination mold. The lamination equipment temperature was raised to 290°C, and preheating was performed at 0.5 MPa pressure for 15 minutes, followed by hot pressing at 15 MPa pressure for 240 minutes. The molding pressure was maintained while cooling down to below 150°C, after which the mold was opened to obtain a pure PPS-based fiber cloth composite board with a thickness of 3.8 mm.

[0045] Example 3 The crushing steps for polyphenylene sulfide are the same as in Example 1.

[0046] 3428.6g PPS powder, 474.3g paraffin wax, 57.1g low-density polyethylene, 11.4g polyethylene glycol, 28.6g stearic acid, and 20g silane coupling agent KH550 were added to a mixing equipment and mixed for 30 minutes at 160℃, top bolt pressure of 0.5MPa, and rotation speed of 30rpm to obtain polyphenylene sulfide rubber compound.

[0047] 0.2mm thick T700 grade carbon fiber plain weave fabric is passed through the hot-coating die head of a multi-layer hot-melt coating equipment via a traction system. The barrel temperature of the hot-coating equipment is raised to 180℃, and the blended adhesive is conveyed to the hot-coating die head through a screw-driven hot-melt coating equipment, coating both sides of the carbon fiber woven fabric. Subsequently, it is compacted through a three-roll mill to obtain a 0.34mm thick polyphenylene sulfide prepreg. The roller temperature is 80℃. The prepreg has many impregnation defects, uneven impregnation, and some fiber fabric layers are not impregnated with adhesive.

[0048] Polyphenylene sulfide (PPS) prepreg sheets were cut to sizes suitable for hot pressing molds using a cutting device. Four layers of the prepreg sheets were then stacked and placed in a hot lamination mold. The lamination equipment temperature was raised to 160°C, and preheating was performed at 0.5 MPa pressure for 10 minutes, followed by hot pressing at 10 MPa pressure for 60 minutes to obtain a 1.3 mm thick preliminary laminate bonded only by a low-temperature degreasing adhesive component. The preliminary laminate was then placed in a degreasing oven and degreased at 250°C in air for 2 hours, followed by degreasing under nitrogen atmosphere for 8 hours. After degreasing, four preliminary laminates were placed in a hot lamination mold. The lamination equipment temperature was raised to 290°C, and preheating was performed at 0.5 MPa pressure for 15 minutes, followed by hot pressing at 15 MPa pressure for 180 minutes. The molding pressure was maintained while cooling down to below 150°C, after which the mold was opened to obtain a pure PPS-based fiber cloth composite board with a thickness of 4.4 mm.

[0049] Example 4 The crushing steps for polyphenylene sulfide are the same as in Example 1.

[0050] 2769.2g PPS powder, 1021.5g paraffin wax, 123.1g low-density polyethylene, 24.6g polyethylene glycol, 61.5g stearic acid, and 20g silane coupling agent KH550 were added to a mixing equipment and mixed for 30 minutes at 160℃, top bolt pressure of 0.5MPa, and rotation speed of 30rpm to obtain polyphenylene sulfide rubber compound.

[0051] 0.2mm thick T700 grade carbon fiber plain weave fabric is passed through the hot-coating die head of a multi-layer hot-melt coating equipment via a traction system. The barrel temperature of the hot-coating equipment is raised to 180℃, and the blended adhesive is conveyed to the hot-coating die head through a screw-driven hot-melt coating device, coating both sides of the carbon fiber woven fabric. Subsequently, it is compacted through a three-roll mill to obtain a 0.29mm thick polyphenylene sulfide prepreg, with the pressure roller temperature at 80℃.

[0052] Polyphenylene sulfide (PPS) prepreg sheets were cut to sizes suitable for hot pressing molds using a cutting device. Four layers of the prepreg sheets were then stacked and placed in a hot lamination mold. The lamination equipment temperature was raised to 160°C, and preheating was performed at 0.5 MPa pressure for 10 minutes, followed by hot pressing at 10 MPa pressure for 60 minutes to obtain a 1.1 mm thick preliminary laminate bonded only by a low-temperature degreasing adhesive component. The preliminary laminate was then placed in a degreasing oven and degreased at 250°C in air for 2 hours, followed by degreasing under nitrogen atmosphere for 9 hours. After degreasing, four preliminary laminates were placed in a hot lamination mold. The lamination equipment temperature was raised to 290°C, and preheating was performed at 0.5 MPa pressure for 15 minutes, followed by hot pressing at 15 MPa pressure for 180 minutes. The molding pressure was maintained while cooling down to below 150°C, after which the mold was opened to obtain a pure PPS-based fiber cloth composite board with a thickness of 3.7 mm.

[0053] Example 5 The crushing steps for polyphenylene sulfide are the same as in Example 1.

[0054] 2757.1g PPS powder, 1118.6g thermoplastic homopolymer oxyacetaldehyde, 87g low-density polyethylene, 24.6g polyethylene glycol, 61.5g stearic acid, and 20g silane coupling agent KH550 were added to a mixing equipment and mixed for 30 minutes at 160℃, top bolt pressure of 0.5MPa, and rotation speed of 30rpm to obtain polyphenylene sulfide rubber compound.

[0055] 0.2mm thick T700 grade carbon fiber plain weave fabric is passed through the hot-coating die head of a multi-layer hot-melt coating equipment via a traction system. The barrel temperature of the hot-coating equipment is raised to 180℃, and the blended adhesive is conveyed to the hot-coating die head through a screw-driven hot-melt coating equipment, coating both sides of the carbon fiber woven fabric. Subsequently, it is compacted through a three-roll mill to obtain a 0.35mm thick polyphenylene sulfide prepreg, with the pressure roller temperature at 80℃.

[0056] Polyphenylene sulfide (PPS) prepreg sheets were cut to sizes suitable for hot pressing molds using a cutting device. Four layers of the prepreg sheets were then stacked and placed in a hot lamination mold. The lamination equipment was heated to 180°C and preheated at 0.5 MPa for 15 minutes, followed by hot pressing at 15 MPa for 60 minutes to obtain a 1.4 mm thick preliminary laminate bonded only by a low-temperature degreasing adhesive component. The preliminary laminate was then placed in a 130°C degreasing furnace, through which a mixture of oxalic acid and nitrogen was introduced for low-temperature catalytic degreasing with oxalic acid for 8 hours. After degreasing, four preliminary laminates were placed in a hot lamination mold. The lamination equipment was heated to 290°C and preheated at 0.5 MPa for 15 minutes, followed by hot pressing at 15 MPa for 180 minutes. The molding pressure was maintained while cooling down to below 150°C, after which the mold was opened to obtain a pure PPS-based fiber cloth composite board with a thickness of 4.4 mm.

[0057] After undergoing 7 days of heat treatment and natural placement to eliminate self-crosslinking factors, the sample products were subjected to performance tests. Interlaminar shear strength test (ISO 14129); tensile test (ISO 527); and flexural test (ISO 14125) were performed.

[0058] Table 1. Performance Test Results of Pure Polyphenylene Sulfide-Based Fiber Fabric Prepreg Sheets

[0059] The examples and data above demonstrate that there is a clear optimization range for the ratio of PPS to binder. Example 1 shows significantly better performance than Examples 3 and 4, which deviated from this ratio. In Example 3, when the PPS ratio was slightly higher, the prepreg exhibited impregnation defects, leading to a decrease in mechanical properties. In Example 4, when the low-temperature degreasing binder component was excessive, the resin matrix ratio was too high, and although the strength index was close to that of Example 1, it did not surpass it. This verifies the scientific validity of the preferred range in the patent; an imbalance in the ratio directly leads to impregnation defects or matrix weakening.

[0060] Process sensitivity is demonstrated in Example 3. Due to a slightly higher PPS ratio, this group experienced "uneven impregnation" during the pre-impregnation stage, resulting in significantly lower interlayer shear strength compared to Example 1 with the optimized ratio. This phenomenon reveals the criticality of rubber flowability control: even slight deviations from the optimal ratio can cause a significant drop in interfacial bonding strength, highlighting the necessity of precisely controlling the mixing parameters as described in the patent.

[0061] The combination of polyoxymethylene (POM)-based binder and oxalic acid-catalyzed degreasing process (Example 5) surpasses traditional solutions in both performance and environmental friendliness; the strict volume ratio of PPS to binder at around 70:30 (Example 1) is crucial for ensuring impregnation quality; and carbon fiber reinforcement forms the fundamental prerequisite for high performance. These data collectively demonstrate that the patented technology, through the innovative combination of low-temperature degreasing binder and solvent-free hot-coating process, effectively solves the long-standing problems of uneven impregnation, weak interfacial bonding, and high energy consumption in PPS composite materials.

[0062] It should be noted that the present invention is not limited to the above-described embodiments. Based on the inventive spirit of the present invention, those skilled in the art can make other changes, and these changes made in accordance with the inventive spirit of the present invention should be included within the scope of protection claimed by the present invention.

Claims

1. A method for preparing pure polyphenylene sulfide-based fiber prepreg sheets, characterized in that, Includes the following steps: A1) Powdering of polyphenylene sulfide; Powdered polyphenylene sulfide resin particles are pulverized into fine powder through a pulverizing process, and the pulverized powder is then sieved into PPS powder of a predetermined particle size by a sieve. A2) Preparation of compounded rubber; PPS powder, low-temperature degreased adhesive component, and additives are added to a mixing device and mixed for a predetermined time within a predetermined temperature range to obtain a polyphenylene sulfide blended rubber. The predetermined temperature range is lower than the thermal degradation temperature or vaporization temperature of the low-temperature degreased adhesive component. The low-temperature degreased adhesive component has a degreasing temperature of less than 270°C, a solid residue of less than 3 wt% after degreasing, and maintains fluidity and adhesion at 50°C to 200°C. A3) Hot-coating prepreg of fiber cloth; the reinforcing fiber cloth is passed through the hot coating head of the multi-layer hot melt coating equipment via a traction system, and the blended adhesive obtained in step A2) is conveyed to the hot coating head via the hot melt coating equipment; then it is compacted by the rolling equipment at a predetermined pressure roller temperature, so that the adhesive penetrates into the gaps between the fiber bundles to form a prepreg sheet. The coating temperature range in this step is 80-200℃, and the predetermined pressure roller temperature range is 70-150℃.

2. The method for preparing pure polyphenylene sulfide-based fiber prepreg sheet as described in claim 1, characterized in that, The volume ratio of the polyphenylene sulfide powder to the low-temperature degreasing binder is 60-80%: 20-40%.

3. The method for preparing pure polyphenylene sulfide-based fiber prepreg sheet as described in claim 1, characterized in that, The low-temperature degreasing adhesive component is one or a combination of two or more of the following: paraffin-based adhesive, polyoxymethylene-based adhesive, moisture-curing reactive polyurethane hot melt adhesive, and polyvinylpyrrolidone-based adhesive; or it is one of the following: paraffin / stearic acid composite adhesive and polyoxymethylene-based adhesive. The paraffin-based adhesive may be a low-temperature degreasing adhesive compounded from paraffin or polyethylene wax, polyethylene glycol, stearic acid, and low-density polyethylene.

4. The method for preparing pure polyphenylene sulfide-based fiber prepreg sheet as described in claim 1, characterized in that, The reinforcing fiber cloth is at least one of carbon fiber cloth, glass fiber cloth, basalt fiber cloth, aramid fiber cloth, poly(p-phenylenebenzodioxazole) fiber cloth, poly(aramiddioxazole) fiber cloth, and ultra-high molecular weight polyethylene fiber cloth.

5. The method for preparing pure polyphenylene sulfide-based fiber prepreg sheet as described in claim 1, characterized in that, The compound material in step A2) also includes a filler component, the mass of which is 0-20% of the sum of the mass of polyphenylene sulfide powder and the low-temperature degreasing binder component; the filler component is one or more of the following: carbon black, carbon fiber short filaments, carbon nanotubes, silicon dioxide, zirconium dioxide, boron nitride, silicon nitride, boron carbide, silicon carbide, talc, alumina, calcium carbonate, etc.

6. The method for preparing pure polyphenylene sulfide-based fiber prepreg sheet as described in claim 1, characterized in that, The additives are one or more of the following: compatibilizers, lubricants, antioxidants, and plasticizers; the mass of the additives is 0.5-5% of the total mass of the blended rubber compound; the volume ratio of the polyphenylene sulfide powder to the low-temperature degreased colloid is 65-75% : 25-35%; the pulverization process in step A1) is to pulverize the polyphenylene sulfide resin particles using a cryogenic airflow pulverizer, with cold nitrogen gas introduced to control the temperature during the pulverization process; the mixing process is an internal mixing process, in which the PPS powder and the low-temperature degreased binder are fully mixed through the high shear force and kneading action within a closed cavity.

7. The method for preparing pure polyphenylene sulfide-based fiber prepreg sheet as described in claim 1, characterized in that, The pulverization process described in step A1) is one of mechanical pulverization or cryogenic pulverization; the D50 of the PPS powder after sieving is 5-50 μm; the mixing process described in step A2) can be one of internal mixing, open milling, or continuous screw extrusion; the predetermined temperature range in step A2) is 80-200℃.

8. A method for preparing a pure polyphenylene sulfide-based fiber cloth composite board, characterized in that, Includes the following steps: B1) Cutting and stacking of prepreg sheets; a method for preparing pure polyphenylene sulfide-based fiber cloth prepreg sheets according to any one of claims 1-7 is used to obtain prepreg sheets, the prepreg sheets are cut into sizes corresponding to hot press molds by cutting equipment, and the prepreg sheets are stacked in 2-20 layers after cutting. B2) Preheating and lamination: The prepreg sheets are laid in layers and placed in a hot lamination mold. The lamination equipment temperature is raised to 150~230℃, preheated at 0.5~2MPa pressure for 1~30min, and then hot-pressed at 2~15MPa pressure for 10~180min to obtain a preliminary laminate bonded by low-temperature degreasing adhesive components. B3) Low-temperature degreasing; the preliminary laminate is placed in a degreasing oven and degreased at 100~250℃ for 1~10 hours; B4) Hot lamination molding; the laminated board after low-temperature degreasing is placed in a hot lamination mold, the lamination equipment temperature is raised to 270~350℃, and the preheating is carried out at 0.5~2MPa pressure for 1~60min, followed by hot pressing, and the pressure is held at 2~25MPa for 10~600min. B5) Cooling and de-temperatureing: Maintain the molding pressure while cooling down to below 150°C, then open the mold to obtain a pure polyphenylene sulfide-based fiber cloth composite board.

9. A pure polyphenylene sulfide-based fiber cloth composite board, characterized in that, It comprises multilayer prepreg sheets formed by lamination and hot lamination, wherein the hot lamination method is to hot press the prepreg sheets prepared according to any one of claims 1-7 after lamination of multiple layers, and the hot pressing conditions are as follows: preheating at 270~350℃ and 0.5~2MPa pressure for 1~60min, followed by hot pressing, and holding at 2~25MPa pressure for 10~600min; further preheating and low-temperature degreasing are performed before hot pressing.

10. The pure polyphenylene sulfide-based fiber cloth composite board as described in claim 9 is applied to the battery cover of new energy vehicles, the overall chassis of automobiles, or aerospace structural components.

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