Flame-retardant and low dielectric loss pps composite, preparation process

Abstract

The present application belongs to the technical field of polymer composites, and particularly relates to a PPS composite material with flame retardance and low dielectric loss and a preparation process. The composite material comprises carboxyl-modified polyphenylene sulfide resin, trifluoro-propyl POSS, hollow silica microspheres treated with silane coupling agent, allylated DOPO, melamine cyanurate, polyphenylene sulfide grafted glycidyl methacrylate and antioxidant. The present application also provides a preparation process of the composite material. The present application anchors the flame-retardant group on the polymer molecular chain through the chemical bonding reaction between the carboxyl-modified polyphenylene sulfide and the allylated DOPO, cooperates the molecular-level low dielectric regulation of trifluoro-propyl POSS and the dielectric optimization of hollow silica microspheres, so that the composite material has the characteristics of efficient flame retardance and low dielectric loss, and can be used in electronic and electrical components with requirements of low signal attenuation transmission and fire safety.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite material technology, specifically relating to a flame-retardant and low dielectric loss PPS composite material and its preparation process. Background Technology

[0002] Polyphenylene sulfide (PPS) is a semi-crystalline thermoplastic engineering plastic whose molecular backbone consists of alternating benzene rings and sulfur atoms. It exhibits excellent thermal stability, chemical resistance, and flame retardancy. PPS has a long-term service temperature of 220-240°C, with even better short-term heat resistance. It also possesses high resistivity and low dielectric constant, and its electrical properties change little with temperature and humidity. Based on these comprehensive performance advantages, PPS is widely used in fields such as electronics, automotive manufacturing, aerospace, and communication equipment where high heat resistance and electrical insulation are required.

[0003] In high-frequency signal transmission scenarios, the dielectric loss of materials is one of the key parameters determining signal integrity and transmission efficiency—the higher the dielectric loss, the more significant the energy attenuation of the signal during transmission, directly affecting communication quality. Meanwhile, communication base stations integrate a large number of high-power-density electronic modules, and the heat accumulation generated during long-term operation makes the fire risk significant; therefore, related plastic components must meet stringent fire safety standards.

[0004] To address the aforementioned application needs, numerous research efforts in recent years have focused on dielectric and flame-retardant modifications of PPS. For example, patent CN119859405A proposes a PPS / LCP composition that reduces the dielectric constant by compounding PPS with a liquid crystal polymer, while simultaneously incorporating a laser sensitizer to balance flame retardancy and laser direct molding capability. While this approach improves the dielectric properties of PPS to some extent, its dielectric loss remains relatively high, failing to meet the stringent requirements for ultra-low dielectric loss in high-frequency components of communication base stations. Furthermore, patent CN117467276A discloses a low-dielectric-loss flame-retardant PPS / PC alloy material, which blends PPS powder with PC resin and adds a reactive flame retardant to balance flame retardancy and dielectric properties. However, the introduction of the PC component into this alloy system, while improving toughness, introduces additional dipole polarization due to the polar characteristics of the carbonate groups in the PC molecular chain under high-frequency electric fields, limiting further reductions in dielectric loss. In addition, some studies have attempted to reduce interfacial polarization by encapsulating low-dielectric fillers in a polymer shell and then combining them with a PPS matrix using microencapsulation technology. However, this process is quite complex and poses significant challenges to the continuous stability and cost control of industrial production.

[0005] Overall, existing technologies either introduce flame-retardant systems that significantly increase dielectric loss, or sacrifice flame-retardant efficiency to achieve low dielectric loss, making it difficult to achieve a balance between the two. Therefore, there is an urgent need to develop a PPS composite material that combines highly efficient flame retardancy with ultra-low dielectric loss, enabling it to simultaneously meet the dual requirements of low signal attenuation transmission and stringent fire safety for high-frequency components in communication base stations. Summary of the Invention

[0006] The purpose of this invention is to provide a flame-retardant and low dielectric loss PPS composite material and its preparation process, aiming to overcome the shortcomings of existing PPS modified materials that cannot simultaneously achieve high efficiency in flame retardancy and ultra-low dielectric loss, so that the composite material has both excellent fire safety and high-frequency signal transmission stability, meeting the high-performance comprehensive requirements of structural materials in electronic and electrical fields such as communication base stations.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a flame-retardant and low dielectric loss PPS composite material, comprising the following components in parts by weight: 55-70 parts of carboxyl-modified polyphenylene sulfide resin; Trifluoropropyl POSS 8-15 parts; 8–18 parts of hollow silica microspheres treated with silane coupling agent; 5-12 parts of allylated DOPO; 3-6 parts of melamine cyanurate; 3-5 parts of polyphenylene sulfide grafted with glycidyl methacrylate; Antioxidant 0.3 to 0.8 parts.

[0008] Further, the carboxyl-modified polyphenylene sulfide resin is prepared by a method comprising the following steps: reacting polyphenylene sulfide resin with succinic anhydride in N-methylpyrrolidone solvent at 100-150°C for 6-10 hours, and obtaining carboxyl-modified polyphenylene sulfide resin after separation and purification.

[0009] Furthermore, the mass ratio of the polyphenylene sulfide resin to succinic anhydride is 1:0.2 to 0.5.

[0010] Furthermore, the silane coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane.

[0011] Further, the allylated DOPO is prepared by a method comprising the following steps: adding DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and allylamine to toluene in a molar ratio of 1:1.05-1.1, reacting under nitrogen protection at 90-100°C for 7-9 hours, and obtaining allylated DOPO after separation and purification.

[0012] Further, the polyphenylene sulfide-grafted glycidyl methacrylate is prepared by a method comprising the following steps: polyphenylene sulfide resin, glycidyl methacrylate and dicumyl peroxide are mixed in a weight ratio of 100:8-12:0.2-0.4, and then melt-grafted and extruded through a twin-screw extruder at 290-305°C, granulated, and dried after acetone extraction to remove unreacted monomers, to obtain polyphenylene sulfide-grafted glycidyl methacrylate.

[0013] Further, the antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or tris[2,4-di-tert-butylphenyl] phosphite.

[0014] While PPS possesses excellent intrinsic flame retardancy, achieving a UL94 V-0 rating typically requires the addition of flame retardants. However, the introduction of flame retardants often increases dielectric loss, a long-standing contradiction in the field. This invention uses carboxyl-modified PPS as a matrix, utilizing the carboxyl group to provide a reaction site. Allylated DOPO molecules possess both flame-retardant phosphaphenanthrene groups and allyl double bonds. These double bonds can react with the carboxyl groups during melt blending, chemically linking the DOPO structure to the PPS molecular chain. This prevents the flame retardant from freely migrating and precipitating within the matrix like conventional additive flame retardants, thus avoiding additional dipole losses due to small molecule movement. The cage-like structure of trifluoropropyl POSS introduces a large amount of free volume, increasing the intersegmentation between molecular chain segments and reducing the polarizable molecular density per unit volume. Simultaneously, the fluorinated groups themselves have low polarizability, which helps suppress the orientation polarization of PPS molecular chain segments under high-frequency electric fields, thereby reducing dielectric loss. Hollow silica microspheres contain enclosed air cavities. Air has a dielectric constant of approximately 1, and the introduction of this air reduces the overall effective dielectric constant of the composite material. PPS-g-GMA improves the interfacial bonding between hollow silica and the matrix. Poor interfacial bonding can lead to defects, which can easily cause localized polarization and increase losses. Therefore, the addition of compatibilizers effectively prevents performance degradation. Melamine cyanurate and allylated DOPO exhibit phosphorus-nitrogen synergy. DOPO captures free radicals in the gas phase, interrupting the combustion chain reaction, while melamine cyanurate releases non-flammable gases to dilute the concentration of combustibles. Although their pathways differ, their directions are consistent, thus achieving a V-0 rating at a relatively low addition level. This avoids the dielectric performance degradation caused by excessive addition of flame retardants in pursuit of flame retardant effects.

[0015] A second aspect of the present invention provides a process for preparing the above-mentioned flame-retardant and low dielectric loss PPS composite material, comprising the following steps: (1) Mix the silane coupling agent-treated hollow silica microspheres, allylated DOPO, melamine cyanurate, polyphenylene sulfide grafted glycidyl methacrylate and antioxidant to obtain premix A; (2) Mix the carboxyl-modified polyphenylene sulfide resin and trifluoropropyl POSS in the specified amounts to obtain premix B; (3) Add premix A to premix B and continue mixing to obtain a mixture; (4) The mixture is added to a twin-screw extruder for melt blending and extrusion, and then granulated to obtain the PPS composite material.

[0016] Further, in step (1), the mixing speed is 200-400 rpm, the mixing time is 3-8 minutes, and the temperature during the mixing process does not exceed 60°C; in step (2), the mixing speed is 400-600 rpm, and the mixing time is 5-10 minutes; in step (3), the mixing speed is 300-500 rpm, and the mixing time is 5-8 minutes.

[0017] Furthermore, the treatment process of the hollow silica microspheres treated with the silane coupling agent includes: adding the hollow silica microspheres and the silane coupling agent into a mixer at a mass ratio of 100:2 to 4, and mixing them at 300 to 500 rpm for 15 to 30 minutes at 90 to 110°C.

[0018] Furthermore, the PPS composite material has a flame retardant rating of UL94 V-0 and a dielectric loss of ≤0.002 at a frequency of 10GHz.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: This invention uses carboxyl-modified polyphenylene sulfide (PPS) as the matrix resin. During melt blending, the carboxyl groups on the PPS molecular chain chemically bond with the allyl double bonds of allylated DOPO, covalently attaching flame-retardant groups to the PPS molecular chain. This effectively avoids the dielectric property degradation caused by migration and precipitation in traditional additive flame retardants. Simultaneously, the low polarization of the fluorinated groups in trifluoropropyl PPS and the free volume effect of the PPS cage structure suppress the orientation polarization of polymer chain segments under high-frequency electric fields at the molecular scale. This, combined with the microscale effect of hollow silica microspheres reducing the effective dielectric constant through their closed cavity structure, jointly optimizes the dielectric properties of the system. Furthermore, allylated DOPO and melamine cyanurate synergistically exert their flame-retardant effects during combustion through two pathways: gas-phase free radical capture and non-flammable gas dilution, achieving highly efficient flame retardancy even at relatively low addition levels. In summary, by combining the above-mentioned technical means, this invention solves the problem of simultaneously achieving flame retardancy and low dielectric loss while maintaining material processing performance and thermal stability. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, all raw materials used in the embodiments are commercially available products. The following sources are illustrative examples.

[0022] Polyphenylene sulfide was purchased from Shanghai Suxincheng New Materials Co., Ltd., model: Ryton® R-7; hollow silica microspheres were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., product name: hollow mesoporous silica, item number: 102888, particle size: 100nm; trifluoropropyl POSS was purchased from Maclean Biochemical Reagents.

[0023] Example 1 This embodiment provides a flame-retardant and low dielectric loss PPS composite material, comprising the following components in parts by weight: 65 parts of carboxyl-modified polyphenylene sulfide resin; 12 portions of trifluoropropyl POSS; 15 portions of hollow silica microspheres treated with silane coupling agent; 8 parts of allylated DOPO; 5 parts of melamine cyanurate; Four parts of polyphenylene sulfide grafted with glycidyl methacrylate; Antioxidant 0.5 parts.

[0024] The antioxidant is a compound composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl] phosphite in a mass ratio of 1:1.

[0025] In this embodiment, the carboxyl-modified polyphenylene sulfide resin was prepared by the following method: Polyphenylene sulfide resin and succinic anhydride were added to N-methylpyrrolidone solvent at a mass ratio of 1:0.35 and reacted at 120°C for 8 hours. After the reaction was completed, the reaction solution was poured into deionized water to precipitate, filtered, and repeatedly washed with deionized water and ethanol. The solution was then vacuum dried at 90°C to constant weight to obtain carboxyl-modified polyphenylene sulfide resin.

[0026] In this embodiment, allylated DOPO was prepared by the following method: DOPO and allylamine were added to toluene at a molar ratio of 1:1.08 and reacted at 95°C for 8 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, and toluene was removed by vacuum distillation. The residue was washed three times with n-hexane and dried under vacuum at 60°C to constant weight to obtain allylated DOPO.

[0027] In this embodiment, polyphenylene sulfide grafted glycidyl methacrylate is prepared by the following method: Polyphenylene sulfide resin, glycidyl methacrylate, and dicumyl peroxide were mixed in a weight ratio of 100:10:0.3 and then melt-grafted at 300°C using a twin-screw extruder. After granulation, unreacted monomers were removed by acetone extraction and the mixture was dried to obtain polyphenylene sulfide grafted glycidyl methacrylate.

[0028] In this embodiment, the hollow silica microspheres treated with silane coupling agent were prepared by the following method: Hollow silica microspheres and γ-glycidoxypropyltrimethoxysilane were added to a high-speed mixer at a mass ratio of 100:3 and mixed at 100°C and 400 rpm for 20 minutes to obtain silane coupling agent-treated hollow silica microspheres.

[0029] The preparation process of the PPS composite material in this embodiment includes the following steps: (1) Weigh out the hollow silica microspheres treated with silane coupling agent, allylated DOPO, melamine cyanurate, polyphenylene sulfide grafted glycidyl methacrylate and antioxidant according to the ratio, put them into a high-speed mixer, mix at 300 rpm for 5 minutes, and control the temperature not to exceed 60℃ during the mixing process to obtain premix A; (2) Weigh the carboxyl-modified polyphenylene sulfide resin and trifluoropropyl POSS according to the ratio, put them into a high-speed mixer, and mix them at 500 rpm for 8 minutes to obtain premix B; (3) Add premix A to premix B and continue mixing at 400 rpm for 6 minutes to obtain a mixture. (4) The mixture is added to a twin-screw extruder for melt blending and extrusion. The twin-screw extruder is set with a first temperature zone to a ninth temperature zone along the material conveying direction. The temperatures of each temperature zone are set as follows: 240℃, 270℃, 290℃, 305℃, 305℃, 300℃, 295℃, 290℃, 285℃. The screw speed is 250 rpm. After extrusion, the mixture is granulated to obtain PPS composite material.

[0030] Example 2 This embodiment provides a flame-retardant and low dielectric loss PPS composite material, comprising the following components in parts by weight: 60 parts of carboxyl-modified polyphenylene sulfide resin; 10 portions of trifluoropropyl POSS; 18 portions of hollow silica microspheres treated with silane coupling agent; 10 parts of allylated DOPO; 4 parts of melamine cyanurate; Five parts of polyphenylene sulfide grafted with glycidyl methacrylate; Antioxidant 0.6 parts.

[0031] The antioxidant is a compound composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 1:1.

[0032] In this embodiment, the carboxyl-modified polyphenylene sulfide resin was prepared by the following method: Polyphenylene sulfide resin and succinic anhydride were added to N-methylpyrrolidone solvent at a mass ratio of 1:0.3 and reacted at 130°C for 7 hours. After the reaction was completed, the reaction solution was poured into deionized water to precipitate, filtered, and repeatedly washed with deionized water and ethanol. The solution was then vacuum dried at 90°C to constant weight to obtain carboxyl-modified polyphenylene sulfide resin.

[0033] In this embodiment, allylated DOPO was prepared by the following method: DOPO and allylamine were added to toluene in a molar ratio of 1:1.06 and reacted at 92°C for 8.5 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, and toluene was removed by vacuum distillation. The residue was washed three times with n-hexane and dried under vacuum at 60°C to constant weight to obtain allylated DOPO.

[0034] In this embodiment, polyphenylene sulfide grafted glycidyl methacrylate is prepared by the following method: Polyphenylene sulfide resin, glycidyl methacrylate, and diisopropylbenzene peroxide were mixed in a weight ratio of 100:8:0.25 and then melt-grafted at 295°C using a twin-screw extruder. After granulation, unreacted monomers were removed by acetone extraction and the mixture was dried to obtain polyphenylene sulfide grafted glycidyl methacrylate.

[0035] In this embodiment, the hollow silica microspheres treated with silane coupling agent were prepared by the following method: Hollow silica microspheres and γ-glycidoxypropyltrimethoxysilane were added to a high-speed mixer at a mass ratio of 100:4 and mixed at 350 rpm for 25 minutes at 105°C to obtain silane coupling agent-treated hollow silica microspheres.

[0036] The preparation process of the PPS composite material in this embodiment includes the following steps: (1) Weigh out the hollow silica microspheres treated with silane coupling agent, allylated DOPO, melamine cyanurate, polyphenylene sulfide grafted glycidyl methacrylate and antioxidant according to the ratio, put them into a high-speed mixer, mix at 250 rpm for 6 minutes, and control the temperature not to exceed 60°C during the mixing process to obtain premix A; (2) Weigh the carboxyl-modified polyphenylene sulfide resin and trifluoropropyl POSS according to the ratio, put them into a high-speed mixer, and mix them at 450 rpm for 9 minutes to obtain premix B; (3) Add premix A to premix B and continue mixing at 350 rpm for 7 minutes to obtain a mixture; (4) The mixture is added to a twin-screw extruder for melt blending and extrusion. The twin-screw extruder is set with a first temperature zone to a ninth temperature zone along the material conveying direction. The temperatures of each temperature zone are set as follows: 240℃, 270℃, 290℃, 305℃, 305℃, 300℃, 295℃, 290℃, 285℃. The screw speed is 250 rpm. After extrusion, the mixture is granulated to obtain PPS composite material.

[0037] Example 3 This embodiment provides a flame-retardant and low dielectric loss PPS composite material, comprising the following components in parts by weight: 68 parts of carboxyl-modified polyphenylene sulfide resin; 14 portions of trifluoropropyl POSS; Ten portions of hollow silica microspheres treated with silane coupling agent; 6 parts of allylated DOPO; 5.5 parts of melamine cyanurate; 3.5 parts of polyphenylene sulfide grafted with glycidyl methacrylate; Antioxidant 0.7 parts.

[0038] The antioxidant is a compound composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 1:1.

[0039] In this embodiment, the carboxyl-modified polyphenylene sulfide resin was prepared by the following method: Polyphenylene sulfide resin and succinic anhydride were added to N-methylpyrrolidone solvent at a mass ratio of 1:0.45 and reacted at 140℃ for 9 hours. After the reaction was completed, the reaction solution was poured into deionized water to precipitate, filtered, and repeatedly washed with deionized water and ethanol. The solution was then vacuum dried at 90℃ to constant weight to obtain carboxyl-modified polyphenylene sulfide resin.

[0040] In this embodiment, allylated DOPO was prepared by the following method: DOPO and allylamine were added to toluene in a molar ratio of 1:1.09 and reacted at 98°C for 7.5 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, and toluene was removed by vacuum distillation. The residue was washed three times with n-hexane and dried under vacuum at 60°C to constant weight to obtain allylated DOPO.

[0041] In this embodiment, polyphenylene sulfide grafted glycidyl methacrylate is prepared by the following method: Polyphenylene sulfide resin, glycidyl methacrylate, and dicumyl peroxide were mixed in a weight ratio of 100:11:0.35 and then melt-grafted at 302°C using a twin-screw extruder. After granulation, unreacted monomers were removed by acetone extraction and the mixture was dried to obtain polyphenylene sulfide grafted glycidyl methacrylate.

[0042] In this embodiment, the hollow silica microspheres treated with silane coupling agent were prepared by the following method: Hollow silica microspheres and γ-glycidoxypropyltrimethoxysilane were added to a high-speed mixer at a mass ratio of 100:2.5 and mixed at 450 rpm for 18 minutes at 95°C to obtain silane coupling agent-treated hollow silica microspheres.

[0043] The preparation process of the PPS composite material in this embodiment includes the following steps: (1) Weigh out the hollow silica microspheres treated with silane coupling agent, allylated DOPO, melamine cyanurate, polyphenylene sulfide grafted glycidyl methacrylate and antioxidant according to the ratio, put them into a high-speed mixer, mix at 350 rpm for 4 minutes, and control the temperature not to exceed 60℃ during the mixing process to obtain premix A; (2) Weigh the carboxyl-modified polyphenylene sulfide resin and trifluoropropyl POSS according to the ratio, put them into a high-speed mixer, and mix them at 550 rpm for 6 minutes to obtain premix B; (3) Add premix A to premix B and continue mixing at 450 rpm for 5.5 minutes to obtain a mixture; (4) The mixture is added to a twin-screw extruder for melt blending and extrusion. The twin-screw extruder is set with a first temperature zone to a ninth temperature zone along the material conveying direction. The temperatures of each temperature zone are set as follows: 240℃, 270℃, 290℃, 305℃, 305℃, 300℃, 295℃, 290℃, 285℃. The screw speed is 250 rpm. After extrusion, the mixture is granulated to obtain PPS composite material.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that the carboxyl-modified polyphenylene sulfide resin was replaced with an equal amount of unmodified polyphenylene sulfide resin. All other aspects are the same as in Example 1.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that allylated DOPO was replaced with an equal amount of unmodified DOPO. All other aspects are the same as in Example 1.

[0046] Comparative Example 3 The difference between this comparative example and Example 1 is that allylated DOPO is replaced with an equal amount of aluminum diethylphosphinate. All other aspects are the same as in Example 1.

[0047] Comparative Example 4 The difference between this comparative example and Example 1 is that trifluoropropyl POSS is replaced with an equal amount of polytetrafluoroethylene. All other aspects are the same as in Example 1.

[0048] Comparative Example 5 The difference between this comparative example and Example 1 is that the hollow silica microspheres treated with silane coupling agent were replaced with an equal amount of mesoporous silica. All other aspects are the same as in Example 1.

[0049] Performance testing 1. Flame retardant properties Test samples: The PPS composite material granules prepared in Examples 1-3 and Comparative Examples 1-5 were injection molded into standard test specimens with a specimen size of 125mm × 13mm × 1.6mm. Five specimens were prepared for each formulation. Before testing, the specimens were placed at 23±2℃ and 50±5% RH for at least 48 hours.

[0050] Test Method: Vertical burning test according to UL94 standard. The sample is held vertically with absorbent cotton placed 300mm below the sample. The Bunsen burner flame height is adjusted to 20mm. Each ignition lasts 10 seconds. The afterflame time (t1) for the first burn, (t2) for the second burn, and (t3) for the afterglow are recorded. Simultaneously, observe whether molten droplets ignite the absorbent cotton and whether the flame spreads to the clamp. Record the t1, t2, and t3 values ​​for all samples to determine the UL94 flame retardancy rating.

[0051] 2. Dielectric properties Test samples: The PPS composite material granules prepared in Examples 1-3 and Comparative Examples 1-5 were injection molded into circular specimens with a diameter of 50 mm and a thickness of 2 mm. Three specimens were prepared for each formulation. Before testing, the specimens were placed at 23±2℃ and 50±5% RH for 24 hours.

[0052] Test method: The resonant cavity perturbation method was used to test at a frequency of 10 GHz. The resonant frequency and quality factor changes before and after loading the sample were measured by a vector network analyzer. The dielectric constant and dielectric loss tangent were calculated and the average value of 3 samples was taken.

[0053] 3. Thermal aging quality change rate Test samples: The PPS composite material granules prepared in Examples 1-3 and Comparative Examples 1-5 were injection molded into test samples with a size of 50mm × 50mm × 2mm. Three test samples were prepared for each formulation. Before testing, the test samples were placed at 23±2℃ and 50±5% RH for 24 hours.

[0054] Test method: Place the sample in a 150℃ forced ventilation oven for 168 hours. Weigh the sample before and after aging (accuracy 0.1mg). Calculate the mass change rate using the following formula and take the average of three samples: Quality change rate (%) = (Post-aging quality - Pre-aging quality) / Pre-aging quality × 100% The test results are shown in Table 1.

[0055] Table 1 Performance Test Results

[0056] The performance test results above show that the composite materials prepared in Examples 1-3 all achieved the UL94 V-0 flame retardant rating, with low dielectric loss and minimal change in quality during thermal aging. In Comparative Example 1, replacing the carboxyl-modified PPS with ordinary PPS resulted in increased weight loss and dielectric loss during thermal aging, indicating that without carboxyl groups as reaction sites, the allylated DOPO could only be physically dispersed in the matrix. The free small molecules experienced additional losses under the electric field and migrated outwards at high temperatures, leading to performance degradation. In Comparative Example 2, replacing the allylated DOPO with ordinary DOPO reduced the flame retardancy to V-1, and the dielectric loss was also higher than in the examples, indicating that after removing the allyl double bond, DOPO existed in a free state in the matrix, resulting in low flame retardant efficiency and impaired dielectric properties. In Comparative Example 3, replacing the allylated DOPO with aluminum diethylphosphines significantly increased dielectric loss and weight loss during thermal aging, indicating that the additive flame retardant had no chemical connection with the matrix, and the free ionic compound experienced high dipole losses under the electric field, leading to significant precipitation at high temperatures. In Comparative Example 4, the dielectric loss increased after replacing trifluoropropyl PPS with PTFE. This was because PTFE and PPS have poor compatibility and uneven dispersion, and the interfacial polarization at the two-phase interface far outweighed the benefits of PTFE's low loss. In Comparative Example 5, the dielectric constant was higher after replacing hollow silica microspheres with mesoporous silica. This was because the open channels of the mesoporous silica were penetrated by PPS during melt blending, and the air inside the pores was expelled, weakening the effect of reducing the effective dielectric constant.

[0057] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flame-retardant and low dielectric loss PPS composite material, characterized in that, The components include the following parts by weight: 55-70 parts of carboxyl-modified polyphenylene sulfide resin; Trifluoropropyl POSS 8-15 parts; 8–18 parts of hollow silica microspheres treated with silane coupling agent; 5-12 parts of allylated DOPO; 3-6 parts of melamine cyanurate; 3-5 parts of polyphenylene sulfide grafted with glycidyl methacrylate; Antioxidant 0.3 to 0.8 parts.

2. The flame-retardant and low dielectric loss PPS composite material according to claim 1, characterized in that, The carboxyl-modified polyphenylene sulfide resin is prepared by a method comprising the following steps: reacting polyphenylene sulfide resin with succinic anhydride in N-methylpyrrolidone solvent at 100-150°C for 6-10 hours, and obtaining carboxyl-modified polyphenylene sulfide resin after separation and purification.

3. The flame-retardant and low dielectric loss PPS composite material according to claim 2, characterized in that, The mass ratio of the polyphenylene sulfide resin to succinic anhydride is 1:0.2 to 0.

5.

4. The flame-retardant and low dielectric loss PPS composite material according to claim 1, characterized in that, The silane coupling agent used in the hollow silica microspheres treated with the silane coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane.

5. The flame-retardant and low dielectric loss PPS composite material according to claim 1, characterized in that, The allylated DOPO is prepared by a method comprising the following steps: adding DOPO and allylamine to toluene in a molar ratio of 1:1.05 to 1.1, reacting under nitrogen protection at 90 to 100°C for 7 to 9 hours, and obtaining allylated DOPO after separation and purification.

6. The flame-retardant and low dielectric loss PPS composite material according to claim 1, characterized in that, The polyphenylene sulfide-grafted glycidyl methacrylate is prepared by a method comprising the following steps: polyphenylene sulfide resin, glycidyl methacrylate and dicumyl peroxide are mixed in a weight ratio of 100:8-12:0.2-0.4, and then the mixture is melt-grafted and extruded through a twin-screw extruder at 290-305°C. After granulation, unreacted monomers are removed by acetone extraction and the mixture is dried to obtain polyphenylene sulfide-grafted glycidyl methacrylate.

7. The flame-retardant and low dielectric loss PPS composite material according to claim 1, characterized in that, The antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or tris[2,4-di-tert-butylphenyl] phosphite.

8. The flame-retardant and low dielectric loss PPS composite material according to claim 1, characterized in that, The PPS composite material has a flame retardant rating of UL94 V-0 and a dielectric loss of ≤0.002 at a frequency of 10GHz.

9. The preparation process of the flame-retardant and low dielectric loss PPS composite material according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Mix the silane coupling agent-treated hollow silica microspheres, allylated DOPO, melamine cyanurate, polyphenylene sulfide grafted glycidyl methacrylate and antioxidant to obtain premix A; (2) Mix the carboxyl-modified polyphenylene sulfide resin and trifluoropropyl POSS in the specified amounts to obtain premix B; (3) Add premix A to premix B and continue mixing to obtain a mixture; (4) The mixture is added to a twin-screw extruder for melt blending and extrusion, and then granulated to obtain the PPS composite material.

10. The preparation process according to claim 9, characterized in that, The process of treating hollow silica microspheres with silane coupling agent includes: adding hollow silica microspheres and silane coupling agent to a mixer at a mass ratio of 100:2 to 4, and mixing at 300 to 500 rpm for 15 to 30 minutes at 90 to 110°C.

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