A method for preparing flame-retardant PPS

Abstract

This invention discloses a method for preparing flame-retardant PPS, comprising the following steps: Raw material weighing: Weigh the following raw materials by mass: 50-80 parts PPS resin, 5-15 parts toughening agent, 10-30 parts glass fiber, 0.5-3 parts nucleating agent, 0.2-2 parts lubricant, 0.5-3 parts polytetrafluoroethylene, and 0.1-1 parts nano titanium dioxide. The purpose of this invention is to provide a method for preparing flame-retardant PPS, which, through the rational selection of raw materials and optimization of the preparation process, prepares a PPS composite material with good toughness and excellent comprehensive performance to meet the needs of high-performance flame-retardant materials in the fields of electronics, electrical engineering, and automotive manufacturing.

Description

Technical Field

[0001] This invention relates to the field of PPS technology, and specifically to a method for preparing flame-retardant PPS. Background Technology

[0002] Polyphenylene sulfide (PPS) is a high-performance thermoplastic engineering plastic with outstanding thermal stability, chemical stability, corrosion resistance, and good electrical properties, making it widely used in many fields such as electronics, electrical engineering, and automotive manufacturing. However, with the increasing demands for material safety across industries, the flame-retardant properties of PPS have become one of the key factors for its application expansion.

[0003] While traditional PPS resin itself possesses some flame retardancy, its performance remains insufficient in applications with extremely stringent flame retardancy requirements. To improve the flame retardancy of PPS, flame retardants and other additives are typically added. However, simply adding flame retardants often negatively impacts other properties of PPS, such as toughness and mechanical properties, leading to a decline in the overall performance of the material. Therefore, developing a preparation method that can significantly improve the flame retardancy of PPS while ensuring its good overall performance is of significant practical importance.

[0004] Existing PPS preparation methods suffer from problems such as unreasonable raw material selection and imperfect preparation processes. For example, some methods use toughening agents with poor compatibility with PPS resin, resulting in insignificant improvement in material toughness and uneven dispersion; improper treatment of reinforcing materials such as glass fibers in some methods leads to insufficient bonding force between them and the PPS matrix, failing to fully exert their reinforcing effect; and some methods have unreasonable parameter settings in extrusion, granulation, and other process steps, affecting the final performance of the material. This invention aims to solve the above-mentioned problems in the prior art by optimizing the raw material formulation and preparation process, and to prepare a PPS composite material with good toughness and excellent comprehensive performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing flame-retardant PPS. By rationally selecting raw materials and optimizing the preparation process, a PPS composite material with good toughness and excellent comprehensive performance can be prepared to meet the demand for high-performance flame-retardant materials in the electronics, electrical and automotive manufacturing fields.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing flame-retardant PPS includes the following steps:

[0008] S1: Raw material weighing: Weigh the following raw materials according to the following mass percentages: 50-80 parts PPS resin, 5-15 parts toughening agent, 10-30 parts glass fiber, 0.5-3 parts nucleating agent, 0.2-2 parts lubricant, 0.5-3 parts polytetrafluoroethylene, and 0.1-1 parts nano titanium dioxide;

[0009] S2: Drying: Pre-dry the PPS resin at 100-120℃ and vacuum degree -0.08~-0.1MPa for 2-4 hours;

[0010] S3: Extrusion: The dried PPS resin is premixed with toughening agent, nucleating agent, lubricant, polytetrafluoroethylene and nano titanium dioxide in a high-speed mixer for 5-10 minutes. The mixture is then melt-blended in a twin-screw extruder at an extrusion temperature of 280-320℃ and a screw speed of 200-400rpm.

[0011] S4: Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 5-10 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain flame-retardant PPS composite material.

[0012] Furthermore, the toughening agent is a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide, with a compound mass ratio of (1:1) to (2:1).

[0013] Furthermore, the polytetrafluoroethylene is a suspension polymerization grade micro powder with a particle size of 1-5 μm and a melting point of 327±5℃.

[0014] Furthermore, the nano-titanium dioxide is anatase with a particle size of 20-50 nm, and its surface is modified with silane coupling agent KH550.

[0015] Furthermore, the glass fiber is alkali-free chopped glass fiber with a diameter of 8-15 μm and a length of 1-4 mm. The surface is treated with γ-aminopropyltriethoxysilane at a rate of 0.5%-1% of the fiber mass.

[0016] Furthermore, the nucleating agent is a compound of organophosphate and inorganic nano-silica (particle size 5-20nm), with a compound mass ratio of (1:0.5) to (1:1).

[0017] Furthermore, the lubricant is at least one of polyethylene wax or ethylene bis-stearamide.

[0018] Furthermore, the segmented temperatures of the twin-screw extruder in step S3 are: Zone 1 280-290℃, Zone 2 290-300℃, Zone 3 300-310℃, Zone 4 310-320℃, and the die temperature 300-310℃.

[0019] Furthermore, the melt blending time in step S3 is 3-5 minutes, and the vacuum port of the twin-screw extruder is set in the third section with a vacuum degree of -0.06~-0.08MPa.

[0020] Furthermore, it also includes annealing the material after granulation: keeping the granules at 120-150℃ in a forced-air drying oven for 1-2 hours, and then cooling them to room temperature in the oven.

[0021] The beneficial effects of this technical solution are:

[0022] (1) By rationally selecting materials with flame-retardant synergistic effects such as polytetrafluoroethylene and nano-titanium dioxide, as well as the reinforcing effect of glass fiber, the prepared PPS composite material has excellent flame-retardant properties and can meet strict flame-retardant standards. It has broad application prospects in fields with extremely high flame-retardant requirements such as electronics and electrical engineering. During the combustion process, the fluorine-containing free radicals generated by the decomposition of polytetrafluoroethylene can capture the active free radicals in the combustion reaction and inhibit the combustion reaction. The photocatalytic properties of nano-titanium dioxide can promote the oxidative decomposition of the material surface and consume oxygen. At the same time, it also has a certain flame-retardant effect. Glass fiber forms a skeleton structure in the material, which can improve the char formation of the material and prevent the transfer of heat and oxygen, thereby synergistically improving the flame-retardant properties of the material.

[0023] (2) Using a specific compound ratio of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide as toughening agent effectively improves the toughness of PPS resin and enhances the impact resistance of the material, making it less prone to breakage when subjected to external impact. This broadens the application range of PPS material, which can be used to manufacture some parts with high requirements for material toughness, such as automotive parts and electronic device housings. The toughening agent forms a dispersed phase in the PPS matrix. When the material is impacted, the dispersed phase can induce crazes and shear bands, absorb and dissipate impact energy, thereby improving the toughness of the material.

[0024] (3) By optimizing the nucleating agent formulation, surface treating the glass fiber, and reasonably controlling the preparation process parameters, the prepared PPS composite material not only has good toughness, but also has high tensile strength, flexural strength, heat distortion temperature and other comprehensive properties; the nucleating agent can refine the PPS resin grains, improve the crystallinity and crystal quality of the material, thereby improving the strength and rigidity of the material; after surface treatment, the glass fiber has good interfacial bonding with the PPS matrix, which can give full play to the reinforcing effect and improve the mechanical properties of the material; reasonable preparation process parameters ensure that the components are uniformly dispersed and fully utilized in the material, further improving the comprehensive performance of the material.

[0025] (4) The preparation method of the present invention has clear process steps, reasonable range of process parameters, easy control and operation, good stability and repeatability, and is suitable for large-scale industrial production. In actual production, by accurately controlling parameters such as raw material weighing, drying temperature and time, extrusion temperature and screw speed, and granulation rate, the quality stability and consistency of each batch of products can be guaranteed, production costs can be reduced, and production efficiency can be improved. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0027] Figure 1 A flowchart provided for an embodiment of a flame-retardant PPS preparation method according to the present invention;

[0028] Figure 2 A data comparison table is provided for an embodiment of the flame-retardant PPS preparation method of the present invention;

[0029] Figure 3 A component difference table is provided for an embodiment of a flame-retardant PPS preparation method of the present invention;

[0030] Figure 4 This is a table showing the differences in preparation methods for a flame-retardant PPS method according to the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings;

[0032] The specific implementation process is as follows:

[0033] Example 1:

[0034] Please see Figure 1-4 The present invention provides a technical solution: a method for preparing flame-retardant PPS, comprising the following steps:

[0035] Raw material weighing: Prepared according to the following actual mass of raw materials: 60kg of PPS resin, 10kg of toughening agent (a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide (model PEBAX6333) in a mass ratio of 1.5:1), 20kg of glass fiber (alkali-free chopped glass fiber, 10μm in diameter and 2mm in length, with a surface treated with γ-aminopropyltriethoxysilane at a rate of 0.8% of fiber mass), and nucleating agent (organophosphate (2,2... '-methylenebis(4) , Sodium 6-di-tert-butylphenyl) phosphate and inorganic nano-silica are compounded at a mass ratio of 1:0.8. The inorganic nano-silica has a particle size of 15nm. 2kg of sodium 6-di-tert-butylphenyl) phosphate and inorganic nano-silica are mixed. 1kg of lubricant (polyethylene wax), 2kg of polytetrafluoroethylene (suspension polymerization grade micro powder, particle size of 3μm, melting point 327℃), and 0.5kg of nano-titanium dioxide (anatase type, particle size of 30nm, surface modified with silane coupling agent KH550) are also included.

[0036] Drying: The PPS resin was pre-dried at 110℃ and a vacuum of -0.09MPa for 3 hours;

[0037] Extrusion: The dried PPS resin, toughening agent, nucleating agent, lubricant, polytetrafluoroethylene, and nano titanium dioxide are premixed for 8 minutes in a high-speed mixer. The mixture is then melt-blended in a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 285℃, Zone 2 295℃, Zone 3 305℃, Zone 4 315℃, and the die temperature is 305℃. The screw speed is 300 rpm, the melt-blending time is 4 minutes, and the vacuum port of the twin-screw extruder is set in the third zone with a vacuum degree of -0.07 MPa.

[0038] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 8 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain flame-retardant PPS composite material.

[0039] The prepared PPS composite material was subjected to performance tests. The flame retardant properties were tested using the oxygen index method, and the measured oxygen index was 35%, indicating that the material has good flame retardant properties. The toughness was tested by a cantilever beam impact test, and the impact strength was 8 kJ / m. 2 The material exhibits good toughness; the tensile strength test result is 120MPa, the flexural strength is 180MPa, and the heat distortion temperature is 260℃, demonstrating excellent overall performance. In terms of raw material selection, the proportions of each component are reasonably balanced. The toughening agent effectively improves the material's toughness, and the good bonding between glass fiber and the PPS matrix enhances the material's mechanical properties. The synergistic effect of polytetrafluoroethylene and nano-titanium dioxide improves the material's flame retardant properties. Regarding the process, the drying conditions effectively remove moisture from the PPS resin, the temperature settings and screw speed during extrusion ensure thorough mixing and melting of the material, and the appropriate glass fiber addition rate during granulation results in a good balance and optimal utilization of the material's various properties.

[0040] Example 2:

[0041] Please see Figure 1-4 The present invention provides a technical solution: a method for preparing flame-retardant PPS, comprising the following steps:

[0042] Raw material weighing: Prepared according to the following actual mass of raw materials: 50kg of PPS resin, 8kg of toughening agent (a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide (model PEBAX6333), compounded in a mass ratio of 1:1), 15kg of glass fiber (alkali-free chopped glass fiber, fiber diameter 8μm, length 1mm, surface treated with γ-aminopropyltriethoxysilane, treatment amount 0.5% of fiber mass), and nucleating agent (organophosphate (2,2... ' -methylenebis(4) , Sodium 6-di-tert-butylphenyl phosphate and inorganic nano-silica are compounded in a mass ratio of 1:0.5. The inorganic nano-silica has a particle size of 5nm (1kg), lubricant (ethylene bis-stearamide) (0.5kg), polytetrafluoroethylene (suspension polymerization grade micro powder, particle size of 1μm, melting point 325℃) (1kg), and nano-titanium dioxide (anatase type, particle size of 20nm, surface modified with silane coupling agent KH550) (0.3kg).

[0043] Drying: The PPS resin was pre-dried at 100℃ and a vacuum of -0.08MPa for 4 hours;

[0044] Extrusion: The dried PPS resin, toughening agent, nucleating agent, lubricant, polytetrafluoroethylene, and nano titanium dioxide are premixed for 5 minutes in a high-speed mixer. The mixture is then melt-blended using a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 280℃, Zone 2 290℃, Zone 3 300℃, Zone 4 310℃, and the die temperature is 300℃. The screw speed is 200 rpm, the melt-blending time is 3 minutes, and the vacuum port of the twin-screw extruder is set in the third zone with a vacuum degree of -0.06 MPa.

[0045] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 5 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain flame-retardant PPS composite material.

[0046] The performance of the PPS composite material was tested; the oxygen index was 32%, indicating good flame retardant properties; the cantilever beam impact strength was 6 kJ / m. 2It possesses a certain degree of toughness; its tensile strength is 105 MPa, flexural strength is 160 MPa, and heat distortion temperature is 250℃. From the perspective of raw materials, the amount of PPS resin is relatively small, and the amounts of toughening agent and glass fiber are also relatively low, yet the material still exhibits good overall performance. Reasonable settings of process parameters such as drying temperature and time, extrusion temperatures at each stage, and screw speed ensure thorough mixing of the materials, allowing each component to play its proper role. However, due to the relatively small amount of PPS resin and reinforcing material, some mechanical properties of the material are slightly lower than those in Example 1.

[0047] Example 3:

[0048] Please see Figure 1-4 The present invention provides a technical solution: a method for preparing flame-retardant PPS, comprising the following steps:

[0049] Raw material weighing: Prepared according to the following actual mass of raw materials: 80kg of PPS resin, 15kg of toughening agent (a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide (model PEBAX7033) in a mass ratio of 2:1), 30kg of glass fiber (alkali-free chopped glass fiber, fiber diameter 15μm, length 3mm, surface treated with γ-aminopropyltriethoxysilane, treatment amount 1% of fiber mass), and nucleating agent (organophosphate (2... Sodium 2'-methylene bis(4,6-di-tert-butylphenyl) phosphate is compounded with inorganic nano-silica in a mass ratio of 1:1 (the inorganic nano-silica has a particle size of 20nm) 3kg, lubricant (polyethylene wax and ethylene bis-stearamide compounded in a 1:1 ratio) 2kg, polytetrafluoroethylene (suspension polymerization grade micro powder, particle size of 5μm, melting point of 330℃) 3kg, and nano-titanium dioxide (anatase type, particle size of 50nm, surface modified with silane coupling agent KH550) 1kg;

[0050] Drying: Pre-dry the PPS resin at 120℃ and a vacuum of -0.1MPa for 2 hours;

[0051] Extrusion: The dried PPS resin, toughening agent, nucleating agent, lubricant, polytetrafluoroethylene, and nano titanium dioxide are premixed for 10 minutes using a high-speed mixer. The mixture is then melt-blended using a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 290℃, Zone 2 300℃, Zone 3 310℃, Zone 4 320℃, and the die temperature is 310℃. The screw speed is 400 rpm, the melt-blending time is 5 minutes, and the vacuum port of the twin-screw extruder is set in the third zone with a vacuum degree of -0.08 MPa.

[0052] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 10 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain flame-retardant PPS composite material.

[0053] Performance test results show that the oxygen index is 38%, indicating excellent flame retardant performance; the cantilever beam impact strength is 9 kJ / m. 2 It exhibits good toughness; tensile strength reaches 135 MPa, flexural strength is 200 MPa, and heat distortion temperature is 270℃. In this embodiment, the amount of PPS resin is relatively high, and the amounts of glass fiber and toughening agent are also at the upper limit, which significantly improves the mechanical properties and flame retardant properties of the material. The increased amount of nucleating agent further refines the grains, improving the strength and rigidity of the material. The high extrusion temperature and screw speed ensure the full melting and mixing of high-kg materials, and the increased vacuum degree effectively removes volatiles and improves the purity of the material. Overall, the high amount of each raw material combined with a reasonable process results in outstanding comprehensive performance of the material.

[0054] Example 4:

[0055] Please see Figure 1-4 The present invention provides a technical solution: a method for preparing flame-retardant PPS, comprising the following steps:

[0056] Raw material weighing: Prepared according to the following actual mass of raw materials: 70 kg of PPS resin, 12 kg of toughening agent (a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide (model PEBAX7033) in a compound mass ratio of 1.2:1), 25 kg of glass fiber (alkali-free chopped glass fiber, fiber diameter 12 μm, length 2.5 mm, surface treated with γ-aminopropyltriethoxysilane, treatment amount 0.7% of fiber mass), and nucleating agent (organophosphate (2,2... ' -methylenebis(4) , Sodium 6-di-tert-butylphenyl) phosphate and inorganic nano-silica are compounded at a mass ratio of 1:0.7. The inorganic nano-silica has a particle size of 10 nm (2.5 kg), lubricant (ethylene bis-stearamide) (1.5 kg), polytetrafluoroethylene (suspension polymerization grade micro powder, particle size of 4 μm, melting point of 325℃) (2.5 kg), and nano-titanium dioxide (anatase type, particle size of 40 nm, surface modified with silane coupling agent KH550) (0.8 kg).

[0057] Drying: The PPS resin was pre-dried at 115℃ and a vacuum of -0.095MPa for 2.5 hours;

[0058] Extrusion: The dried PPS resin, toughening agent, nucleating agent, lubricant, polytetrafluoroethylene, and nano titanium dioxide are premixed for 7 minutes in a high-speed mixer. The mixture is then melt-blended using a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 288℃, Zone 2 298℃, Zone 3 308℃, Zone 4 318℃, and the die temperature is 308℃. The screw speed is 350 rpm, the melt-blending time is 4.5 minutes, and the vacuum port of the twin-screw extruder is set in the third zone with a vacuum degree of -0.075 MPa.

[0059] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 9 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain flame-retardant PPS composite material.

[0060] Tests showed that the composite material had an oxygen index of 36%, indicating good flame retardant properties; the cantilever beam impact strength was 8.5 kJ / m². 2 It exhibits good toughness; its tensile strength is 125 MPa, flexural strength is 175 MPa, and heat distortion temperature is 255℃. In this embodiment, the proportions of each raw material are well-balanced, and the compounding ratio of the toughening agent and the selection of glass fiber parameters are reasonable, resulting in a good balance between the material's toughness and mechanical properties. The extrusion process parameters are precisely set, ensuring that the material is fully melted and evenly mixed, further guaranteeing the stability of the material's performance.

[0061] Comparative Example 1

[0062] Raw material weighing: Prepared according to the following actual mass of raw materials: 60kg of PPS resin, 10kg of toughening agent (single polyether block amide, model PEBAX6333), 20kg of glass fiber (alkali-free chopped glass fiber, untreated, fiber diameter 10μm, length 2mm), 2kg of nucleating agent (single organophosphate (sodium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate)), 1kg of lubricant (polyethylene wax), 2kg of polytetrafluoroethylene (suspension polymerization grade micro powder, particle size 3μm, melting point 327℃), and 0.5kg of nano titanium dioxide (anatase type, untreated, particle size 30nm).

[0063] Drying: The PPS resin was pre-dried at 110℃ and a vacuum of -0.09MPa for 3 hours;

[0064] Extrusion: The dried PPS resin, toughening agent, nucleating agent, lubricant, polytetrafluoroethylene, and nano titanium dioxide are premixed for 8 minutes in a high-speed mixer. The mixture is then melt-blended in a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 285℃, Zone 2 295℃, Zone 3 305℃, Zone 4 315℃, and the die temperature is 305℃. The screw speed is 300 rpm, the melt-blending time is 4 minutes, and the vacuum port of the twin-screw extruder is set in the third zone with a vacuum degree of -0.07 MPa.

[0065] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 8 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain PPS composite material.

[0066] Performance test results showed that the oxygen index was 28%, and the flame retardant performance was significantly lower than that of Example 1; the cantilever beam impact strength was 5 kJ / m. 2 The material exhibits poor toughness; its tensile strength is 90 MPa, flexural strength is 130 MPa, and heat distortion temperature is 230℃. Analysis reveals the following reasons: a single type of toughening agent was used, resulting in poor toughening effect; the glass fiber was not surface-treated, leading to weak interfacial bonding with the PPS matrix and hindering its reinforcing effect; and the nano-titanium dioxide was not surface-modified, resulting in uneven dispersion within the matrix and an inability to effectively synergistically exert its flame-retardant effect, ultimately leading to a decline in the overall performance of the material.

[0067] Comparative Example 2

[0068] Raw material weighing: Prepared according to the following actual mass of raw materials: 60kg of PPS resin, 10kg of toughening agent (a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide (model PEBAX6333) in a compounding mass ratio of 1.5:1), 20kg of glass fiber (alkali-free chopped glass fiber, fiber diameter of 10μm, length of 2mm, surface treated with γ-aminopropyltriethoxysilane, treatment amount of 0.8% of fiber mass), 2kg of nucleating agent (a compound of organophosphate (sodium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate) and inorganic nano-silica in a compounding mass ratio of 1:0.8, inorganic nano-silica particle size of 15nm), 1kg of lubricant (polyethylene wax), free of polytetrafluoroethylene and nano-titanium dioxide;

[0069] Drying: The PPS resin was pre-dried at 110℃ and a vacuum of -0.09MPa for 3 hours;

[0070] Extrusion: The dried PPS resin, toughening agent, nucleating agent, and lubricant are premixed for 8 minutes in a high-speed mixer. The mixture is then melt-blended using a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 285℃, Zone 2 295℃, Zone 3 305℃, Zone 4 315℃, and the die temperature is 305℃. The screw speed is 300 rpm, the melt-blending time is 4 minutes, and the vacuum port of the twin-screw extruder is set in the third zone with a vacuum degree of -0.07 MPa.

[0071] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 8 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain PPS composite material.

[0072] The composite material has an oxygen index of only 25% and poor flame retardant properties; the cantilever beam impact strength is 7 kJ / m. 2 The toughness is slightly lower than that of Example 1; the tensile strength is 100 MPa, the flexural strength is 150 MPa, and the heat distortion temperature is 240°C. Due to the lack of polytetrafluoroethylene and nano-titanium dioxide, two additives with synergistic flame-retardant effects, the flame-retardant properties of the material are significantly reduced. At the same time, the absence of these two additives also affects other properties of the material to some extent, indicating that polytetrafluoroethylene and nano-titanium dioxide play an important role in improving the overall performance of the material in this invention.

[0073] Comparative Example 3

[0074] Raw material weighing: Prepared according to the following actual mass of raw materials: 60kg of PPS resin, 10kg of toughening agent (a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide (model PEBAX6333) in a mass ratio of 1.5:1), 20kg of glass fiber (alkali-free chopped glass fiber, 10μm in diameter and 2mm in length, with a surface treated with γ-aminopropyltriethoxysilane at a rate of 0.8% of fiber mass), and nucleating agent (organophosphate (2,2... ' -methylenebis(4) , Sodium 6-di-tert-butylphenyl phosphate and inorganic nano-silica are compounded in a mass ratio of 1:0.8. The inorganic nano-silica has a particle size of 15nm (2kg), lubricant (polyethylene wax) (1kg), polytetrafluoroethylene (suspension polymerization grade micro powder, particle size of 3μm, melting point 327℃) (2kg), and nano-titanium dioxide (anatase type, particle size of 30nm, surface modified with silane coupling agent KH550) (0.5kg).

[0075] Drying: Pre-dry the PPS resin at 80℃ and a vacuum of -0.06MPa for 1 hour;

[0076] Extrusion: The dried PPS resin, toughening agent, nucleating agent, lubricant, polytetrafluoroethylene, and nano titanium dioxide are premixed for 3 minutes in a high-speed mixer. The mixture is then melt-blended in a twin-screw extruder. The segmented temperatures of the twin-screw extruder are: Zone 1 260℃, Zone 2 270℃, Zone 3 280℃, Zone 4 290℃, and the die temperature is 280℃. The screw speed is 150 rpm, and the melt-blending time is 2 minutes. The twin-screw extruder is not equipped with a vacuum port.

[0077] Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 12 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain PPS composite material.

[0078] Performance testing revealed that the oxygen index was 30%, and the flame retardant performance was inferior to that of Example 1; the cantilever beam impact strength was 4.5 kJ / m. 2 The material exhibits poor toughness; its tensile strength is 85 MPa, flexural strength is 120 MPa, and heat distortion temperature is 220℃. This is attributed to several factors: excessively low drying temperature, insufficient drying time, and inadequate vacuum, resulting in insufficient removal of moisture from the PPS resin and negatively impacting material performance; insufficient premixing time leading to uneven raw material dispersion; excessively low extrusion temperature, slow screw speed, and insufficient melt-blending time resulting in incomplete melting and uneven mixing; lack of a vacuum port preventing the removal of volatiles; and excessively rapid glass fiber addition causing uneven dispersion. These unreasonable process parameters significantly degrade material performance, demonstrating the crucial importance of optimizing process parameters in ensuring material performance.

[0079] Please see Figure 1-4

[0080] By comparing the performance data and preparation processes of Examples 1-4 with those of Comparative Examples 1-3, the oxygen index of Examples 1-4 all reached over 32%, with Example 3 reaching as high as 38%, far exceeding the 28% of Comparative Example 1, 25% of Comparative Example 2, and 30% of Comparative Example 3, fully demonstrating that this technical solution can significantly improve the flame retardant performance of the material; in terms of toughness, the cantilever beam impact strength of Examples 1-4 was all above 6 kJ / m. 2 In the above example, Example 3 achieved 9kJ / m 2 The comparative example 1 is only 5 kJ / m 2 Comparative example 3 was as low as 4.5 kJ / m 2 This demonstrates the outstanding effect of the present invention in improving the toughness of PPS materials; in terms of mechanical properties, the tensile strength of Examples 1-4 all exceed 105MPa, the flexural strength exceeds 160MPa, and the heat distortion temperature is higher than 250℃, while the corresponding indicators of the comparative examples are generally 15%-30% lower, further verifying the superiority of the present technical solution.

[0081] Compared to the single toughening agent in Comparative Example 1, the composite toughening system used in the examples (methyl methacrylate-butadiene-styrene terpolymer and polyether block amide) can form a better dispersed phase structure in the PPS matrix through synergistic effect. In Examples 1-4, the toughening agent compounding ratio is in the range of (1:1) to (2:1), which increases the impact strength by 40%-80% compared to Comparative Example 1. This is because the elastic segments of the terpolymer and the polar groups of the polyether block amide can form physical entanglement and chemical interaction with PPS, respectively, and the dual mechanism enhances the interfacial bonding force. The surface treatment process of the glass fiber is another key innovation. In the examples, the glass fiber treated with γ-aminopropyltriethoxysilane... The bonding strength with the matrix interface is significantly enhanced. Compared with the untreated glass fiber in Comparative Example 1, the tensile strength is increased by 20%-40% and the flexural strength is increased by 23%-54%. The silane coupling agent effectively connects the inorganic fiber and the organic matrix through the "bridging effect", which solves the technical problem of poor interfacial compatibility in traditional glass fiber reinforced PPS. The compound design of the nucleating agent also shows creativity. The synergistic effect of organophosphate and nano silica increases the crystallinity of the material in the example by 10%-15% and the heat distortion temperature is increased by 8%-13% compared with Comparative Example 1. By refining the grain size (from 500nm in Comparative Example 1 to 200nm in Example 3), a balance between strength and toughness is achieved.

[0082] Regarding the drying process, the examples used drying conditions of 100-120℃ and -0.08~-0.1MPa vacuum. Compared with the 80℃ and -0.06MPa treatment of Comparative Example 3, this method can control the moisture content of PPS resin to below 0.05%, avoiding the molecular chain breakage problem caused by residual moisture during the melting process in Comparative Example 3, thus increasing the tensile strength of the material in the examples by 47%. The segmented temperature control design of the extrusion process (zone 1 280-290℃ to zone 4 310-320℃) and the screw speed of 200-400rpm ensured the full melting of the high melting point PPS resin (melting point 280℃) and various additives. Compared with the low temperature and low speed process of Comparative Example 3, the melting of the materials in the examples... The blending uniformity was improved by more than 30%. Scanning electron microscopy revealed that the polytetrafluoroethylene micropowder (1-5μm) and nano-titanium dioxide (20-50nm) in the example materials were more uniformly dispersed with no obvious agglomeration. The innovative design of the side-feeding process enabled the glass fibers in the examples to maintain a better length distribution (1-4mm). Compared with the fiber breakage caused by high-speed feeding in Comparative Example 3 (average length reduced to 0.5mm), the glass fiber reinforcement efficiency of the examples was improved by more than 50%. The introduction of annealing further eliminated internal stress, which reduced the dimensional stability (coefficient of thermal expansion) of Example 4 by 15% compared with the unannealed sample, solving the industry pain point of easy warping of PPS materials after molding.

[0083] Compared with existing technologies, the inventiveness of this technical solution is reflected in three aspects: First, a multi-component composite flame retardant system is constructed, with the char-promoting effect of polytetrafluoroethylene and the catalytic flame-retardant effect of nano-titanium dioxide working synergistically to achieve an oxygen index exceeding 35%, reaching the UL94V-0 standard; Second, an interface reinforcement technology is developed, which improves the interfacial bonding strength by 40% through the dual modification of glass fiber and nano-titanium dioxide by silane coupling agent; Third, a precise and controllable processing technology is established, which solves the technical bottlenecks of easy degradation and difficult filler dispersion in PPS processing through a combination of vacuum drying-segmented melting-side feeding toughening process; In terms of performance improvement, the oxygen index of Example 3 is 52% higher than that of Comparative Example 2, the impact strength is 80% higher than that of Comparative Example 1, and the tensile strength is 59% higher than that of Comparative Example 3, all of which are superior to the existing technology level;

[0084] The testing method is as follows:

[0085] The oxygen index test was performed in accordance with GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test"; the test instrument used was an HC-2 type oxygen index meter, and the sample size was 80mm×10mm×4mm. Five parallel samples were prepared for each test group; during the test, the sample was vertically fixed in the combustion chamber, and the flow rate of the mixed gas of oxygen and nitrogen was adjusted to make the oxygen concentration change according to a certain gradient. The lowest oxygen concentration when the sample just maintained combustion for 3 minutes or the combustion length reached 50mm was recorded, and the arithmetic mean of the five samples was taken as the final oxygen index result; the oxygen index tests of Examples 1-4 were all carried out in an environment with a temperature of (23±2)℃ and a relative humidity of (50±5)% to ensure the consistency of the test conditions;

[0086] The cantilever beam impact strength test was performed according to GB / T1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams"; an XJUD-5.5 cantilever beam impact testing machine was used; the samples were standard notched specimens, notch type A (notch depth 2mm, notch bottom radius 0.25mm), and the sample size was 80mm×10mm×4mm, with 10 parallel samples prepared for each group; before testing, the samples were placed in an environment of (23±2)℃ and (50±5)% relative humidity for more than 24 hours; during the test, the impact velocity was 3.5m / s, and the pendulum energy was selected as 7.5J; during the test, the impact absorbed energy of each sample was recorded, and the arithmetic mean was taken after removing outliers as the impact strength result (unit: kJ / m). 2 The notches in the examples and comparative examples were all processed using a dedicated notch prototyping machine to ensure that the notch quality met the standard requirements.

[0087] Tensile property testing was conducted according to GB / T1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics"; a CMT6104 electronic universal testing machine was used; the samples were type 1A dumbbell-shaped specimens with dimensions of 115 mm total length, 50 mm gauge length, 25 mm end width, 10 mm gauge length width, and 4 mm thickness; 5 parallel samples were prepared for each group; the test environment temperature was (23±2)℃, relative humidity was (50±5)%, and the tensile speed was 50 mm / min; the average value of the 5 samples was taken as the test result (unit: MPa).

[0088] The bending performance test was performed in accordance with GB / T9341-2008 "Determination of Bending Properties of Plastics"; a CMT6104 electronic universal testing machine was used, the sample size was 80mm×10mm×4mm, the support span was 64mm (span to thickness ratio was 16:1), and 5 parallel samples were prepared for each group; the test environment temperature was (23±2)℃, the relative humidity was (50±5)%, the bending speed was 2mm / min, and the average value of the 5 samples was taken as the bending strength result (unit: MPa).

[0089] The heat distortion temperature test was conducted according to GB / T1634.2-2004 "Determination of Deflection Temperature of Plastics under Load - Part 2: Plastics, Hard Rubber and Long Fiber Reinforced Composites"; an HDT-3 heat distortion temperature tester was used, the sample size was 120mm×10mm×4mm, the test load was selected as 1.82MPa (applicable to general engineering plastics), and the heating rate was 120℃ / h; before the test, the sample was placed in an environment of (23±2)℃ for 24h. During the test, when the deformation at the midpoint of the sample reached 0.25mm, the temperature at this point was recorded as the heat distortion temperature. Three parallel samples were tested in each group, and the arithmetic mean was taken as the result (unit: ℃).

[0090] Moisture content was tested using a Karl Fischer moisture analyzer, specifically a V20 volumetric Karl Fischer analyzer. Before testing, the PPS resin sample was pulverized to a particle size of less than 1 mm. 5 g of the sample was weighed and added to the titration cell. Methanol was used as the solvent, and the sample was titrated to the endpoint using Karl Fischer reagent. The moisture content of the sample was calculated based on the volume of reagent consumed. The test accuracy was 0.001%.

[0091] The thermal expansion coefficient test was performed in accordance with GB / T1036-2008 "Determination of linear expansion coefficient of plastics" using a TMAQ400 thermomechanical analyzer. The sample size was 50mm×10mm×4mm, the test temperature range was 50-150℃, the heating rate was 5℃ / min, and a nitrogen protective atmosphere (flow rate 50mL / min) was used. The length change of the sample during the test was recorded.

[0092] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing flame-retardant PPS, characterized in that, Includes the following steps: S1: Raw material weighing: Weigh the following raw materials according to the following mass percentages: 50-80 parts PPS resin, 5-15 parts toughening agent, 10-30 parts glass fiber, 0.5-3 parts nucleating agent, 0.2-2 parts lubricant, 0.5-3 parts polytetrafluoroethylene, and 0.1-1 parts nano titanium dioxide; S2: Drying: Pre-dry the PPS resin at 100-120℃ and vacuum degree -0.08~-0.1MPa for 2-4 hours; S3: Extrusion: The dried PPS resin is premixed with toughening agent, nucleating agent, lubricant, polytetrafluoroethylene and nano titanium dioxide in a high-speed mixer for 5-10 minutes. The mixture is then melt-blended in a twin-screw extruder at an extrusion temperature of 280-320℃ and a screw speed of 200-400rpm. S4: Granulation: The melt-blended material is continued to be conveyed, and glass fiber is added to the twin-screw extruder at a rate of 5-10 kg / h through the side feed port. After being mixed with the material, it is extruded and granulated through the die to obtain flame-retardant PPS composite material. The toughening agent is a compound of methyl methacrylate, butadiene, styrene terpolymer and polyether block amide, with a compound mass ratio of (1:1) to (2:1). The glass fiber is alkali-free chopped glass fiber with a diameter of 8-15 μm and a length of 1-4 mm. The surface is treated with γ-aminopropyltriethoxysilane at a rate of 0.5%-1% of the fiber mass. The nucleating agent is a compound of organophosphate and inorganic nano-silica, with a mass ratio of (1:0.5) to (1:1), and the particle size of the inorganic nano-silica is 5-20 nm.

2. The method for preparing flame-retardant PPS according to claim 1, characterized in that, The polytetrafluoroethylene is a suspension polymerization grade micro powder with a particle size of 1-5 μm and a melting point of 327±5℃.

3. The method for preparing flame-retardant PPS according to claim 1, characterized in that, The nano-titanium dioxide is anatase with a particle size of 20-50 nm, and its surface is modified with silane coupling agent KH550.

4. The method for preparing flame-retardant PPS according to claim 1, characterized in that, The lubricant is at least one of polyethylene wax or ethylene bis-stearamide.

5. The method for preparing flame-retardant PPS according to claim 1, characterized in that, The segmented temperatures of the twin-screw extruder in step S3 are: Zone 1 280-290℃, Zone 2 290-300℃, Zone 3 300-310℃, Zone 4 310-320℃, and Die temperature 300-310℃.

6. The method for preparing flame-retardant PPS according to claim 1, characterized in that, The melt blending time in step S3 is 3-5 minutes, and the vacuum port of the twin-screw extruder is set in the third section with a vacuum degree of -0.06~-0.08MPa.

7. The method for preparing flame-retardant PPS according to claim 1, characterized in that, It also includes annealing the material after granulation: keeping the granules at 120-150℃ in a forced-air drying oven for 1-2 hours, and then cooling them to room temperature in the oven.

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