A method for preparing modified raw materials for end face sealing strips of scroll compressors

Abstract

This invention relates to the field of polymer materials technology and discloses a method for modifying and preparing raw materials for scroll compressor end face sealing strips. The method includes: adding polyphenylene sulfide, inorganic silica fume, maleic anhydride, pyromellitic dianhydride, and triglycidyl isocyanate to the front section of a twin-screw extruder for melt mixing to obtain a premixed melt; conveying it to the middle section for vacuum devolatilization, then adding polycarbodiimide and pre-dried synthetic hydrotalcite for mixing to obtain a treated melt; conveying it to the rear section for adding composite nucleating masterbatch and alkali-free glass fiber for mixing and extrusion; finally, cooling the modified extruded strip in a water-cooling tank and pelletizing it to obtain the final raw material. This invention, through segmented acid removal and nucleation induction, inhibits the thermal degradation of the substrate and accelerates the crystallization rate, reducing molding warpage errors and ensuring the dimensional and performance stability of the modified raw material for scroll compressor end face sealing strips.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a method for modifying and preparing raw materials for a scroll compressor end face sealing strip. Background Technology

[0002] The end face sealing strip inside a scroll compressor is a component that ensures a tight seal between the moving and stationary discs and reduces gas leakage. These sealing strips are typically thin and operate under high temperature and pressure conditions, requiring strict dimensional tolerances during manufacturing. Current technology usually uses polyphenylene sulfide (PPS) as the base material, modifying the raw material by adding inorganic fillers before injection molding to improve the material's mechanical and heat resistance properties.

[0003] Because polyphenylene sulfide (PPS) crystallizes slowly, existing end-face sealing strips typically incorporate inorganic nucleating agents into the substrate during production to promote crystallization. Thin-walled sealing strips require high melt flowability, necessitating that the modified raw materials maintain a stable melt state under the high temperatures of injection molding. To ensure the demolded product achieves the required crystallinity and maintains dimensional stability, a prolonged high-temperature secondary annealing treatment is usually required after molding.

[0004] However, residual free acidic substances in polyphenylene sulfide (PPS) can easily trigger thermal degradation of polymeric segments under prolonged high-temperature heating, and also affect the nucleation activity of inorganic nucleating agents. This phenomenon makes the crystallization process of the material difficult to control, leading to uneven shrinkage of thin-walled sealing strips during cooling and molding, resulting in warping and dimensional errors. Furthermore, relying on secondary annealing to eliminate residual stress not only prolongs the production cycle, but prolonged heating can also accelerate the thermal aging of the substrate, leading to polymer performance degradation and ultimately affecting the long-term sealing effect of the sealing strip during actual operation.

[0005] Therefore, this invention proposes a method for modifying and preparing raw materials for end face sealing strips of scroll compressors to address the shortcomings of existing technologies. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for modifying and preparing end-face sealing strips for scroll compressors. The technical problem solved by this invention is that, during operation, the end-face sealing strips used in existing scroll compressors are subjected to long-term high temperatures and pressures, placing high demands on the crystallization and stability of the molding raw materials. However, in conventional modification processes, residual acidic impurities in polyphenylene sulfide are prone to thermal degradation, leading to fluctuations in the molded dimensions of the product and affecting its long-term sealing performance.

[0007] To address the above problems, the present invention provides the following technical solution: This invention provides a method for modifying and preparing raw materials for end face sealing strips of scroll compressors, employing the following technical solution: A method for modifying and preparing a raw material for a scroll compressor end face sealing strip, wherein the raw material used in the modification preparation method comprises, by weight, the following components: 100 parts polyphenylene sulfide, 5-15 parts inorganic silica fume, 0.5-1.5 parts maleic anhydride, 0.03-0.30 parts pyromellitic dianhydride, 0.10-0.80 parts triglycidyl isocyanurate, 0.10-0.60 parts polycarbodiimide, 0.20-1.20 parts synthetic hydrotalcite, 3.5-9.5 parts composite nucleating masterbatch, and 20-45 parts alkali-free glass fiber; the modification preparation method includes the following steps: S1, mixing the polyphenylene sulfide, the inorganic silica fume, the maleic anhydride, and the pyromellitic dianhydride with the... S1. After mixing the triglycidyl isocyanurate, it is added to the front section of a twin-screw extruder and melt-mixed to obtain a premixed melt; S2. The premixed melt is conveyed to the middle section of the twin-screw extruder, and the vacuum exhaust port is opened for devolatilization treatment. Then, the polycarbodiimide and the pre-dried synthetic hydrotalcite are added from the side feed port and mixed to obtain a treated melt; S3. The treated melt is conveyed to the rear section of the twin-screw extruder, and the composite nucleating masterbatch and the alkali-free glass fiber are added from the side feed port. After mixing and extrusion, modified extruded strips are obtained; S4. The modified extruded strips are cooled in a water cooling tank and then pelletized to obtain modified end-face sealing strip raw materials.

[0008] By adopting the above technical solution, this invention distributes polyphenylene sulfide and various additive components to different sections for melt mixing according to the process sequence. During the initial mixing process, the anhydride groups provided by maleic anhydride and pyromellitic dianhydride can undergo a ring-opening reaction with the epoxy groups in triglycidyl isocyanate under heated melting conditions. This reaction is beneficial for improving the interfacial bonding between inorganic silica fume and the polyphenylene sulfide matrix.

[0009] As the melt is transported to the mid-section and undergoes vacuum devouring to remove some small molecules, polycarbodiimide and synthetic hydrotalcite are incorporated. The carbodiimide groups carried by the polycarbodiimide can undergo addition reactions with residual acidic end groups or free acidic impurities within the melt, forming corresponding addition products. Combined with the layered bimetallic hydroxide structure of the synthetic hydrotalcite, which adsorbs and neutralizes free acidic substances, both components work together to reduce the extractable acid value. This process helps lower the extractable acid value within the melt, reduces the likelihood of thermal degradation of polyphenylene sulfide segments due to acid catalysis, and mitigates the risk of significant fluctuations in the melt flow state.

[0010] The melt, after acid conditioning, enters the later stage. The lower acid value environment reduces the likelihood of residual acid interfering with the active sites of the subsequently added nucleating agent. The composite nucleating masterbatch is dispersed in the matrix, serving as heterogeneous nucleation sites to guide the cooling and crystallization of polyphenylene sulfide. Combined with the physical filling of alkali-free glass fiber, this provides support to the matrix. The modified material prepared through the above operations exhibits relatively stable rheological and crystallization behavior during subsequent injection molding, keeping molding errors within a reasonable range and contributing to the long-term maintenance of end-face sealing.

[0011] Preferably, the raw materials, by weight, consist of the following components: 100 parts of polyphenylene sulfide, 10 parts of inorganic silica fume, 1 part of maleic anhydride, 0.15 parts of pyromellitic dianhydride, 0.40 parts of triglycidyl isocyanurate, 0.30 parts of polycarbodiimide, 0.60 parts of synthetic hydrotalcite, 6 parts of composite nucleating masterbatch, and 35 parts of alkali-free glass fiber.

[0012] By adopting the above technical solution, the specific weight parts of each raw material component are defined. Under the above ratio conditions, the active groups consumed in the pre-grafting reaction, the neutralizing components introduced in the mid-stage acid adjustment process, and the amount of nucleation and reinforcing materials in the post-stage are mutually adapted, which helps to improve the overall mechanical properties of the material and maintain its thermal performance.

[0013] Preferably, in step S1, the mixing time is 3-8 minutes, the temperature of the front section of the twin-screw extruder is set to 290-310℃, and the screw speed of the twin-screw extruder is 300-450 rpm. In step S2, the devolatilization treatment controls the vacuum degree to -0.06 MPa to -0.09 MPa, the pre-drying temperature is 110-130℃, and after adding the polycarbodiimide and the synthetic hydrotalcite, they are mixed at 300-310℃ for 20-60 seconds. In step S3, the temperature from the rear section of the twin-screw extruder to the die head is set to 315-330℃.

[0014] By adopting the above technical solution, the set temperatures and processing times for each stage are adapted to the processing state of the material. The initial temperature environment of 290-310℃ promotes the melting of polyphenylene sulfide and activates the reactive groups; the middle stage is set with a negative pressure environment and a mixing condition of 300-310℃, which facilitates the escape of volatile components and the reaction process of carbodiimide groups; the final stage temperature is increased to 315-330℃, mainly to compensate for the local heat loss after the addition of alkali-free glass fiber, so as to maintain the normal flow of the melt.

[0015] Preferably, the preparation method of the composite nucleating master powder includes the following steps: Step 1, adding hexagonal boron nitride to a mixed solvent composed of anhydrous ethanol and water, and ultrasonically treating it at 25°C to obtain a hexagonal boron nitride dispersion; Step 2, adding pimelic acid and calcium hydroxide sequentially to the hexagonal boron nitride dispersion, raising the temperature and stirring the reaction to obtain a deposition suspension; Step 3, adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the deposition suspension, maintaining the temperature and continuing to stir to obtain a treated suspension; Step 4, filtering the treated suspension to separate solid and liquid, washing it with water, placing it in a vacuum drying oven for drying, and then pulverizing and sieving it to obtain the composite nucleating master powder.

[0016] By employing the above technical solution, the preparation of the composite nucleation masterbatch utilizes a mixed solvent of anhydrous ethanol and water as a medium to disperse hexagonal boron nitride under ultrasonication. After introducing pimelic acid and calcium hydroxide, the calcium pimelic acid generated by acid-base neutralization is deposited on the outer surface of the hexagonal boron nitride particles. Subsequently added γ-(2,3-epoxypropoxy)propyltrimethoxysilane, after hydrolysis, can react with the inorganic surface to form silane-treated inorganic composite nuclei. When these composite nuclei are added to the melt, they provide a thermally conductive path while inducing polymer segments to crystallize at the particle interface, helping to shorten the overall crystallization time.

[0017] Preferably, the raw materials for preparing the composite nucleating masterbatch, by weight, comprise: 3-8 parts of hexagonal boron nitride, 30-80 parts of the mixed solvent, 0.15-0.60 parts of pimelic acid, 0.07-0.28 parts of calcium hydroxide, and 0.10-0.80 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane; wherein the volume ratio of anhydrous ethanol to water in the mixed solvent is 1:1. In step 1, the ultrasonic treatment time is 30-60 minutes; in step 2, the target temperature for raising the temperature is 60-80℃, the stirring speed is 300-500 rpm, and the stirring time is 1-3 hours; in step 3, the specific temperature for maintaining the temperature is 60-80℃, the stirring speed for continuing is 300-500 rpm, and the stirring time for continuing is 0.5-1 hour; in step 4, the drying temperature is 110-130℃, the drying time is 4-6 hours, and the sieve mesh size for pulverizing and sieving is 270-330 mesh.

[0018] By adopting the above technical solution, the raw material ratio and preparation conditions of the composite nucleating masterbatch are standardized. Maintaining anhydrous ethanol and water at a certain volume ratio controls the precipitation process of calcium pimecrolate. Combined with the set heating temperature and stirring speed, this facilitates the surface treatment process, reduces powder agglomeration, and improves the uniformity of powder dispersion in polyphenylene sulfide.

[0019] Preferably, the twin-screw extruder is a co-rotating parallel twin-screw extruder. The barrel of the twin-screw extruder is sequentially arranged along the material conveying direction as a main feed port, a first zone, a second zone, a third zone, a fourth zone, a fifth zone, a sixth zone, a seventh zone, an eighth zone, and a die head. The first, second, and third zones constitute the front section, which is internally equipped with a high-shear kneading block. The main feed port is located in the first zone. The fourth and fifth zones constitute the middle section, with the vacuum exhaust port located in the fourth zone and the side feed port located in the fifth zone. The sixth, seventh, and eighth zones constitute the rear section, which is internally equipped with a low-shear conveying threaded element. The side feed port is located in the sixth zone. The die head has an internal homogenization zone. The side feeding port includes a first side feeding port and a second side feeding port arranged in parallel along the material flow direction. The first side feeding port and the second side feeding port are used to independently add the composite nucleating master powder and the alkali-free glass fiber, respectively. In step S4, the specific process of cooling treatment and pelletizing is as follows: the modified extruded strip extruded from the die head is drawn into a stainless steel constant temperature water cooling tank with a length of 4 to 6 meters, and the cooling water temperature is controlled at 60°C to 80°C for cooling and shaping. After the modified extruded strip is drawn out of the water, the surface moisture is dried by a high-pressure air knife array, and finally sent into a cantilevered roller pelletizer to be cut into near-cylindrical particles with a length of 3-4 mm.

[0020] By adopting the above technical solution, the threaded elements configured in different sections of the extruder are matched with each process stage. The front section uses a high-shear kneading block to provide shear force to promote micro-dispersion between components; the rear section uses low-shear conveying elements to reduce the cutting wear on alkali-free glass fibers and retain some fiber length. In addition, the forming stage is equipped with a water-cooling tank and a high-pressure air knife array to reduce the degree of non-uniform shrinkage during strip cooling and remove surface moisture, which is beneficial for cutting particles with more regular dimensions.

[0021] This invention provides a method for modifying and preparing raw materials for end face sealing strips of scroll compressors. It has the following beneficial effects: 1. This invention reduces the content of extractable acidic components in the melt by incorporating polycarbodiimide and synthetic hydrotalcite after devolatilization, leveraging their addition and adsorption effects. This treatment helps reduce the risk of thermal degradation of polyphenylene sulfide at high temperatures and minimizes melt flow fluctuations caused by molecular chain degradation. Controlling the residual acid value through the above modification steps provides a relatively thermally stable raw material for subsequent molding, facilitating dimensional stability of the injection-molded end-face sealing strip during long-term operation of the scroll compressor.

[0022] 2. This invention disperses a composite nucleating masterbatch in an acid-treated melt, utilizing its surface crystal nucleus structure to establish heterogeneous nucleation sites within the polymer. This component guides the relatively concentrated aggregation of macromolecular chain segments during cooling, which is beneficial for improving the overall crystallization rate and crystallinity. This raw material processing method aims to alleviate the shrinkage and warping tendency of thin-walled parts during cooling, reducing the product's dependence on a secondary annealing process. After this modification, the flatness of the injection-molded end-face sealing strip is improved, easily meeting the high-precision assembly tolerance requirements of scroll compressors.

[0023] 3. This invention utilizes the ring-opening reaction of acid anhydride and epoxy components to improve the interfacial bonding between polyphenylene sulfide and inorganic silica fume, and incorporates alkali-free glass fiber in the low-shear region. Surface treatment of the micro-interface improves the bonding between the matrix and powder filler, while the adjusted extrusion conveying shear also helps retain some fiber length. Combined with the appropriate formulation of the raw materials, this modification process gives the material relatively good tensile strength and impact resistance. This helps the end-face sealing strip maintain its rigidity and prevent brittle fracture when subjected to the complex alternating loads inside the scroll compressor. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method for preparing the raw material modification of the scroll compressor end face sealing strip according to the present invention. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0026] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0027] Polyphenylene sulfide (PPS), CAS No. 26125-40-6, is a linear polymer whose main chain is composed of alternating benzene rings and sulfur atoms. Its weight-average molecular weight is controlled between 35,000 and 50,000, and its melt flow rate can be 80 to 120 g / 10 min at 300°C.

[0028] Inorganic silica fume, CAS number 69012-64-2, is mainly composed of amorphous silica with an average particle size of 2 to 5 μm.

[0029] Alkali-free glass fiber, with a single filament diameter of 10 to 13 μm, in a short-cut shape with a length of 3 to 5 mm.

[0030] Hexagonal boron nitride, CAS number 10043-11-5, has a graphite-like layered structure with an average particle size of 5 to 10 μm.

[0031] Polycarbodiimide is a high molecular weight polymer with multiple -N=C=N- functional groups in its main chain, and a weight-average molecular weight of 3,000 to 5,000.

[0032] The synthetic hydrotalcite, CAS number 11097-59-9, has a layered bimetallic hydroxide structure with an interlayer spacing of 0.75 to 0.80 nm.

[0033] Maleic anhydride, CAS number 108-31-6.

[0034] Pyromellitic dianhydride, CAS number 89-32-7.

[0035] Triglycidyl isocyanurate, CAS number 2451-62-9.

[0036] Pimelic acid, CAS number 111-16-0.

[0037] Calcium hydroxide, CAS number 1305-62-0.

[0038] γ-(2,3-epoxypropoxy)propyltrimethoxysilane, CAS number 2530-83-8.

[0039] Anhydrous ethanol, CAS number 64-17-5.

[0040] Unless otherwise stated, "parts" in the following preparation examples, embodiments and comparative examples refer to parts by weight; the composite nucleating masterbatch obtained from each preparation example can be scaled up and used in subsequent embodiments and comparative examples at the same weight ratio.

[0041] Preparation Example 1: This preparation example provides a method for preparing a composite nucleating masterbatch, including the following steps: Step 1: Add 5 parts of hexagonal boron nitride to 50 parts of a mixed solvent consisting of anhydrous ethanol and water in a volume ratio of 1:1, and sonicate at 25°C for 45 minutes to obtain a hexagonal boron nitride dispersion. Step 2: Add 0.35 parts of pimelic acid and 0.16 parts of calcium hydroxide to the hexagonal boron nitride dispersion in sequence, raise the temperature to 70°C, and stir the mixture at 400 rpm for 2 hours to obtain the sedimentation suspension. Step 3: Add 0.40 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the sedimentation suspension, maintain the temperature at 70℃ and continue stirring at 400 rpm for 0.8 hours to obtain the treated suspension; Step 4: The treated suspension is filtered to separate solid and liquid components. After washing with deionized water three times, it is placed in a vacuum drying oven and dried at 120°C for 5 hours. Then, it is pulverized with a pulverizer and passed through a 300-mesh sieve to obtain composite nucleating mother powder.

[0042] Preparation Example 2: This preparation example provides a method for preparing a composite nucleating masterbatch, including the following steps: Step 1: Add 3 parts of hexagonal boron nitride to 30 parts of a mixed solvent consisting of anhydrous ethanol and water in a volume ratio of 1:1, and sonicate at 25°C for 30 minutes to obtain a hexagonal boron nitride dispersion. Step 2: Add 0.15 parts of pimelic acid and 0.07 parts of calcium hydroxide to the hexagonal boron nitride dispersion in sequence, raise the temperature to 60°C, and stir the mixture at 300 rpm for 1 hour to obtain the sedimentation suspension. Step 3: Add 0.10 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the sedimentation suspension, maintain the temperature at 60℃ and continue stirring at 300 rpm for 0.5 hours to obtain the treated suspension; Step 4: The treated suspension is filtered to separate solid and liquid, washed three times with deionized water, placed in a vacuum drying oven and dried at 110°C for 4 hours, then pulverized with a pulverizer and passed through a 270-mesh sieve to obtain composite nucleating mother powder.

[0043] Preparation Example 3: This preparation example provides a method for preparing a composite nucleating masterbatch, including the following steps: Step 1: Add 8 parts of hexagonal boron nitride to 80 parts of a mixed solvent consisting of anhydrous ethanol and water in a volume ratio of 1:1, and sonicate at 25°C for 60 minutes to obtain a hexagonal boron nitride dispersion. Step 2: Add 0.60 parts of pimelic acid and 0.28 parts of calcium hydroxide to the hexagonal boron nitride dispersion in sequence, raise the temperature to 80°C, and stir the mixture at 500 rpm for 3 hours to obtain the sedimentation suspension. Step 3: Add 0.80 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the sedimentation suspension, maintain the temperature at 80℃ and continue stirring at 500 rpm for 1 hour to obtain the treated suspension. Step 4: The treated suspension is filtered to separate solid and liquid. After washing with deionized water three times, it is placed in a vacuum drying oven and dried at 130°C for 6 hours. Then, it is pulverized with a pulverizer and passed through a 330-mesh sieve to obtain composite nucleating mother powder.

[0044] Reference Figure 1Examples 1 to 3 below provide a method for modifying and preparing raw materials for end face sealing strips of scroll compressors. The preparation method includes the following steps: S1: premixed extrusion; S2: devolatilization and acid adjustment; S3: side-feeding mixing; S4: cooling and pelletizing to obtain modified end face sealing strip raw materials.

[0045] Example 1: This embodiment provides a method for modifying and preparing raw materials for a scroll compressor end face sealing strip, including the following steps: S1. Add 100 parts of polyphenylene sulfide, 10 parts of inorganic silica fume, 1 part of maleic anhydride, 0.15 parts of pyromellitic dianhydride, and 0.40 parts of triglycidyl isocyanate to a high-speed mixer and mix for 5 minutes. Then add the mixture through the main feed port of a twin-screw extruder. Set the temperature of the front section of the twin-screw extruder (i.e., zones 1 to 3) to 300°C and the screw speed to 350 rpm. After melt mixing, a premixed melt is obtained. S2. The premixed melt is conveyed to the middle section of the twin-screw extruder (i.e., zone 4 to zone 5). In zone 4, the vacuum exhaust port is opened and the vacuum degree is controlled at -0.08MPa for devolatilization treatment. Then, 0.30 parts of polycarbodiimide and 0.60 parts of synthetic hydrotalcite pre-dried at 120°C are added from the side feed port of zone 5. The mixture is then kneaded at 305°C for 40 seconds to obtain the treated melt. S3. The processed melt is conveyed to the rear section of the twin-screw extruder (i.e., zones 6 to 8). Six parts of the composite nucleating masterbatch prepared in Preparation Example 1 and 35 parts of alkali-free glass fiber are added from the side feed port of zone 6. The temperature from zone 6 to the die head is set to 320°C. After mixing and extrusion, the modified extruded strip is obtained. S4. After the modified extruded strip is cooled in a water cooling tank, it is sent to a pelletizer for pelletizing to obtain the modified end face sealing strip raw material.

[0046] Example 2: This embodiment provides a method for modifying and preparing raw materials for a scroll compressor end face sealing strip, including the following steps: S1. Add 100 parts of polyphenylene sulfide, 5 parts of inorganic silica fume, 0.5 parts of maleic anhydride, 0.03 parts of pyromellitic dianhydride, and 0.10 parts of triglycidyl isocyanate to a high-speed mixer and mix for 3 minutes. Then add the mixture through the main feed port of a twin-screw extruder. Set the temperature of the front section of the twin-screw extruder (i.e., zones 1 to 3) to 290°C and the screw speed to 300 rpm. After melt mixing, a premixed melt is obtained. S2. The premixed melt is conveyed to the middle section of the twin-screw extruder (i.e., zone 4 to zone 5). In zone 4, the vacuum exhaust port is opened and the vacuum degree is controlled at -0.06MPa for devolatilization treatment. Then, 0.10 parts of polycarbodiimide and 0.20 parts of synthetic hydrotalcite pre-dried at 110°C are added from the side feed port of zone 5. The mixture is kneaded at 300°C for 20 seconds to obtain the treated melt. S3. The processed melt is conveyed to the rear section of the twin-screw extruder (i.e., zones 6 to 8). 3.5 parts of the composite nucleating masterbatch powder prepared in Preparation Example 2 and 20 parts of alkali-free glass fiber are added from the side feed port of zone 6. The temperature from zone 6 to the die head is set to 315°C. After mixing and extrusion, the modified extruded strip is obtained. S4. After the modified extruded strip is cooled in a water cooling tank, it is sent to a pelletizer for pelletizing to obtain the modified end face sealing strip raw material.

[0047] Example 3: This embodiment provides a method for modifying and preparing raw materials for a scroll compressor end face sealing strip, including the following steps: S1. Add 100 parts of polyphenylene sulfide, 15 parts of inorganic silica fume, 1.5 parts of maleic anhydride, 0.30 parts of pyromellitic dianhydride, and 0.80 parts of triglycidyl isocyanate to a high-speed mixer and mix for 8 minutes. Then add the mixture through the main feed port of a twin-screw extruder. Set the temperature of the front section of the twin-screw extruder (i.e., zones 1 to 3) to 310°C and the screw speed to 450 rpm. After melt mixing, a premixed melt is obtained. S2. The premixed melt is conveyed to the middle section of the twin-screw extruder (i.e., zone 4 to zone 5). In zone 4, the vacuum exhaust port is opened and the vacuum degree is controlled at -0.09MPa for devolatilization treatment. Then, 0.60 parts of polycarbodiimide and 1.20 parts of synthetic hydrotalcite pre-dried at 130°C are added from the side feed port of zone 5. The mixture is then kneaded at 310°C for 60 seconds to obtain the treated melt. S3. The processed melt is conveyed to the rear section of the twin-screw extruder (i.e., zones 6 to 8). 9.5 parts of the composite nucleating masterbatch powder prepared in Preparation Example 3 and 45 parts of alkali-free glass fiber are added from the side feed port of zone 6. The temperature from zone 6 to the die head is set to 330°C. After mixing and extrusion, the modified extruded strip is obtained. S4. After the modified extruded strip is cooled in a water cooling tank, it is sent to a pelletizer for pelletizing to obtain the modified end face sealing strip raw material.

[0048] In a preferred embodiment, the specific process of cooling the modified extruded strip in a water-cooling tank and then feeding it into a pelletizer for pelletizing in Examples 1 to 3 is as follows: the modified extruded strip extruded from the die head is drawn into a stainless steel constant temperature water-cooling tank with a length of 4 to 6 meters, and the cooling water temperature is controlled at 60°C to 80°C for cooling and shaping; after the strip is drawn out of the water, the surface moisture is dried by a high-pressure air knife array, and finally it is fed into a cantilevered roller pelletizer to be cut into near-cylindrical end-face sealing strip modified particles with a length of 3mm to 4mm.

[0049] In a preferred embodiment, the twin-screw extruders of Examples 1 to 3 are co-rotating parallel twin-screw extruders. The barrel is sequentially arranged along the material conveying direction with a main feed inlet, zones 1, 2, 3, 4, 5, 6, 7, 8, and a die head. Zones 1 to 3 constitute the front section; zones 4 to 5 constitute the middle section; and zones 6 to 8 constitute the rear section. The main feed inlet is located in zone 1. Zones 1 to 3 are equipped with high-shear kneading blocks. A vacuum exhaust port is located in zone 4. The side feed inlets of the middle section are located in zone 5. The side feed inlets of the rear section are located in zone 6, specifically including a first side feed inlet and a second side feed inlet arranged parallel along the material flow direction, used for independently adding composite nucleating masterbatch and alkali-free glass fiber, respectively. Zones 6 to 8 are equipped with low-shear conveying threaded elements. A homogenization zone is located inside the die head.

[0050] Example 4: This embodiment provides a method for preparing an end face sealing strip for a scroll compressor, using the modified end face sealing strip raw material obtained in Example 1 as the processing material, specifically including the following steps: S1. Place the modified end-face sealing strip raw material obtained in Example 1 in a hot air drying oven, set the drying temperature to 75-85℃, and continuously dry for 1.5-2.5 hours to remove surface moisture; S2. Feed the dried modified end-face sealing strip raw material into the hopper of an injection molding machine for injection molding, set the injection temperature of the injection molding machine barrel to 300-330℃, and set the mold temperature to 130-150℃; S3. Control the injection pressure to 8... The injection pressure is 0-120 MPa, and the injection time is 1-3 seconds, so that the melt completely fills the mold cavity; then it enters the holding pressure stage, setting the holding pressure to 60-90 MPa and the holding time to 3-5 seconds, to compensate for the volume shrinkage of the melt during the cooling process; finally, it enters the cooling and shaping stage, with a cooling time of 6-7 seconds, controlling the total injection cycle of injection, holding pressure and cooling to 10-15 seconds; S4, after the injection cycle is completed, the mold is opened and ejected to obtain the molded scroll compressor end face sealing strip.

[0051] Comparative Example 1: Compared with Example 1, the difference is that 0.30 parts of polycarbodiimide and 0.60 parts of synthetic hydrotalcite in step S2 of Example 1, and 6 parts of the composite nucleating masterbatch powder and 35 parts of alkali-free glass fiber in step S3 are all transferred to step S1 and mixed with 100 parts of polyphenylene sulfide, 10 parts of inorganic silica fume, 1 part of maleic anhydride, 0.15 parts of pyromellitic dianhydride, and 0.40 parts of triglycidyl isocyanate in a high-speed mixer for 5 minutes, and all of them are added through the main feed port of the twin-screw extruder; and the side feed port in zone 5 of step S2 is not fed, and the side feed port in zone 6 of step S3 is not fed, and the rest are the same.

[0052] Comparative Example 2: Compared with Example 1, the difference is that in step S2, only 0.30 parts of polycarbodiimide are added from the side feed port of zone 5, and 0.60 parts of synthetic hydrotalcite are not added, while the rest are the same.

[0053] Comparative Example 3: Compared with Example 1, the difference is that in step S2, only 0.60 parts of synthetic hydrotalcite pre-dried at 120°C were added from the side feed port of zone 5, and 0.30 parts of polycarbodiimide were not added, while the rest were the same.

[0054] Comparative Example 4: Compared with Example 1, the difference is that in step S3, instead of adding 6 parts of the composite nucleating masterbatch powder prepared in Preparation Example 1 from the side feed port of Zone 6, a physical mixer is added. The physical mixer is prepared by adding 5 parts of hexagonal boron nitride, 0.43 parts of calcium pimecronate (CAS No. 19455-79-9) and 0.40 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a high-speed mixer and mixing for 5 minutes. All other parts are the same.

[0055] Comparative Example 5: Compared with Example 1, the difference is that in step S2, 0.30 parts of polycarbodiimide and 0.60 parts of synthetic hydrotalcite are not added from the side feed port of zone 5; instead, the above-mentioned 0.30 parts of polycarbodiimide and 0.60 parts of synthetic hydrotalcite are postponed to step S3. 0.30 parts of polycarbodiimide, 0.60 parts of synthetic hydrotalcite, and 6 parts of the composite nucleating masterbatch prepared in Preparation Example 1 are added from the first side feed port of zone 6. 35 parts of alkali-free glass fiber are still added from the second side feed port of zone 6. The rest are the same.

[0056] Test Example 1: Experimental steps: 1. The test subjects were divided into four groups, specifically: the first group was the premixed melt collected at the end of zone 3 at the end of step S1 in Example 1, serving as the initial reference sample; the second group was the treated melt collected at the end of zone 5 at the end of step S2 in Comparative Example 2, serving as the treated sample of Comparative Example 2; the third group was the treated melt collected at the end of zone 5 at the end of step S2 in Comparative Example 3, serving as the treated sample of Comparative Example 3; and the fourth group was the treated melt collected at the end of zone 5 at the end of step S2 in Example 1, serving as the treated sample of Example 1. The amount of melt sample collected in each group was not less than 10g.

[0057] 2. The melt samples obtained in each of the above stages were placed in liquid nitrogen for cooling and quenching, and then placed in an ultra-micro pulverizer for pulverization. The powder samples of 60 to 80 mesh were collected by sieving and placed in a vacuum drying oven for drying at 80°C for 2 hours.

[0058] 3. Weigh 5.00g of each powder sample and place them in a conical flask equipped with a reflux condenser. Add 100mL of a mixed solvent prepared by mixing toluene and anhydrous ethanol in a volume ratio of 2:1. Place the conical flask in a 95℃ water bath and heat under reflux for 1.5 hours to allow the extractable acidic components in the sample to enter the liquid phase.

[0059] 4. After the extract has cooled to room temperature, filter it under vacuum. Wash the filter residue twice with a small amount of toluene and combine the filtrates. Using an automatic potentiometric titrator, dissolve 2.8 g of potassium hydroxide in anhydrous ethanol and bring the volume to 1000 mL. Standardize the solution to a concentration of 0.05 mol / L potassium hydroxide-anhydrous ethanol. Titrate the filtrate with the potassium hydroxide-anhydrous ethanol solution and record the volume of titrant consumed at the titration endpoint.

[0060] Measure 100 mL of a mixed solvent prepared from toluene and anhydrous ethanol at a volume ratio of 2:1. Without adding the powder sample, place the solution in an Erlenmeyer flask equipped with a reflux condenser and heat under reflux in a 95°C water bath for 1.5 hours. After cooling to room temperature, titrate using an automatic potentiometric titrator with the same titrant. Record the volume consumed at the titration endpoint to complete the blank solvent titration test. The extraction acid value is calculated by subtracting the volume of titrant consumed in the blank solvent from the volume of titrant consumed in the actual sample titration, converting it to the amount of potassium hydroxide consumed (in milligrams), and then dividing by the mass of the powder sample. The unit is mgKOH / g.

[0061] The extraction acid values ​​of the initial reference sample, the treatment sample of Comparative Example 2, the treatment sample of Comparative Example 3, and the treatment sample of Example 1 were denoted as A0, A1, A2, and A3, respectively; where A0 was 10.85 mg KOH / g, A1 was 3.12 mg KOH / g, A2 was 4.86 mg KOH / g, and A3 was 0.58 mg KOH / g.

[0062] The acid value reduction rates of the samples treated in Comparative Example 2, Comparative Example 3, and Example 1 were denoted as R1, R2, and R3, respectively, and calculated according to the following formulas: R1 = (A0 - A1) / A0 × 100%, R2 = (A0 - A2) / A0 × 100%, R3 = (A0 - A3) / A0 × 100%.

[0063] The experimental results are shown in Table 1: Table 1: Test results of extraction acid value and acid value reduction rate for each test group

[0064] Note: "-" indicates that the reference sample of Example 1 is used as the basis for calculating the acid value reduction rate, and the acid value reduction rate is not calculated.

[0065] Test conclusion: According to the data in Table 1, the extraction acid value of the reference sample in Example 1 was 10.85 mg KOH / g. After treatment in step S2, the extraction acid values ​​of the treated samples in Comparative Example 2, Comparative Example 3, and Example 1 were 3.12 mg KOH / g, 4.86 mg KOH / g, and 0.58 mg KOH / g, respectively, with corresponding acid value reduction rates of 71.24%, 55.21%, and 94.65%.

[0066] Under the same vacuum devolatilization conditions, the samples treated in Comparative Example 2 and Comparative Example 3, respectively, were treated with polycarbodiimide and synthetic hydrotalcite, and their extraction acid values ​​were lower than those of the initial reference samples. The sample treated in Example 1, which was treated with both polycarbodiimide and synthetic hydrotalcite, had an extraction acid value lower than that of the samples treated in Comparative Example 2 and Comparative Example 3, and its acid value reduction rate was higher than that of the samples treated in Comparative Example 2 and Comparative Example 3.

[0067] The above test results show that, under the test conditions, the extractable acidic component content of the treated melt obtained after the co-addition of polycarbodiimide and synthetic hydrotalcite is lower than that when polycarbodiimide or synthetic hydrotalcite is added separately. After the S2 step, the extractable acid value of the melt treated in Example 1 decreased to 0.58 mg KOH / g, providing a melt condition with a lower acid value for the subsequent addition of composite nucleating masterbatch.

[0068] Test Example 2: Experimental steps: 1. The test subjects were divided into eight groups, specifically: Groups 1 to 3 used the modified end-face sealing strip raw materials prepared in Examples 1 to 3, respectively; Groups 4 to 8 used the modified end-face sealing strip raw materials prepared in Comparative Examples 1 to 5, respectively. Each group of raw materials was placed in a vacuum drying oven at 120°C for 4 hours, and the sample size of each group after drying was no less than 50g.

[0069] 2. Weigh out the dried raw materials for each group and place them in an injection molding machine to form circular samples with a diameter of 12.7 mm and a thickness of 2.0 mm. Each group should produce at least one circular sample. Set the injection molding temperature to 320℃ and the mold temperature to 140℃. Use a laser flash thermal conductivity meter to test the thermal diffusivity of the circular samples, a differential scanning calorimeter to test the specific heat capacity of the circular samples, and Archimedes' buoyancy method to test the density of the circular samples. The thermal conductivity is obtained by calculating the product of the thermal diffusivity, specific heat capacity, and density. Record the thermal conductivity of each group of samples.

[0070] 3. Weigh 8.0 mg of each group of dried raw materials, place them in an aluminum crucible, press them into tablets, seal the tablets, and place them in a differential scanning calorimeter to test the exothermic crystallization behavior. Under high-purity nitrogen purging at 50 mL / min, raise the temperature to 320℃ at a rate of 20℃ / min and hold it at that temperature for 5 minutes for heat history treatment; then cool the temperature to 150℃ at a cooling rate of 10℃ / min.

[0071] 4. Record the heat flow curve during the cooling process. Select the main peak of exothermic crystallization on the heat flow curve and determine the height from the peak top to the baseline. Draw a straight line parallel to the baseline at half the height. This straight line intersects the two sides of the exothermic peak at two points. Read the temperature difference between these two points and record this temperature difference as the half-peak width of the exothermic crystallization peak. The half-peak width of the exothermic crystallization peak is used to characterize the width of the exothermic crystallization peak during the cooling process. A smaller half-peak width indicates that the exothermic crystallization process is more concentrated.

[0072] The experimental results are shown in Table 2: Table 2: Test results of thermal conductivity and full width at half maximum (FWHM) of crystallization exothermic peak for each test group

[0073] Test conclusion: According to the data in Table 2, the comparative example 4 test sample, which introduced hexagonal boron nitride and nucleating agent through physical mixing, had a thermal conductivity of 0.96 W / (m·K) and a half-peak width at half-maximum (WHM) of 11.27 °C for the exothermic crystallization peak. Compared with Example 1, the thermal conductivity of the comparative example 4 test sample was lower, and the WHM of the exothermic crystallization peak was larger, indicating that the thermal conductivity and the concentration of exothermic crystallization of the material obtained by the physical mixing method were lower than those of Example 1.

[0074] Comparative Example 1 was mixed using a one-pot method, and its thermal conductivity was 0.85 W / (m·K), with a half-peak width of 12.54 °C for the exothermic crystallization peak. These results indicate that the thermal conductivity of the sample in Comparative Example 1 is lower than that in Examples 1 to 3, and the half-peak width of the exothermic crystallization peak is greater than that in Examples 1 to 3.

[0075] The thermal conductivity of Comparative Examples 2, 3, and 5 ranged from 1.18 to 1.25 W / (m·K), and the half-peak width of the exothermic crystallization peak ranged from 8.65 to 9.46 °C. The thermal conductivity of these three comparative examples was lower than that of Examples 1 to 3, and the half-peak width of the exothermic crystallization peak was greater than that of Examples 1 to 3, indicating that their thermal conductivity and the concentration of exothermic crystallization were lower than those of Examples 1 to 3.

[0076] The test samples of Examples 1 to 3 used the composite nucleating masterbatch prepared in Examples 1 to 3, which had a thermal conductivity of 1.42 to 2.13 W / (m·K) and a half-maximum width at half maximum (WHM) of the exothermic crystallization peak of 3.41 to 5.38 °C. Compared with Comparative Examples 1 to 5, the test samples of Examples 1 to 3 had higher thermal conductivity and smaller WHM of the exothermic crystallization peak. This result indicates that the material obtained by using the composite nucleating masterbatch and processing it according to the feeding sequence described in the examples has higher thermal conductivity and a more concentrated exothermic crystallization peak.

[0077] Test Example 3: Experimental steps: 1. The test subjects were divided into eight groups, specifically: Groups 1 to 3 used the modified end-face sealing strip raw materials prepared in Examples 1 to 3, respectively; Groups 4 to 8 used the modified end-face sealing strip raw materials prepared in Comparative Examples 1 to 5, respectively. The eight groups of modified end-face sealing strip raw materials were placed in a vacuum drying oven at 120°C for 4 hours, and the sample weight of each group after drying was no less than 80g.

[0078] 2. Weigh out the dried raw materials for each group and put them into the injection molding machine. Set the injection molding machine barrel temperature to 320℃ and the mold temperature to 140℃. Injection mold to obtain a strip-shaped test specimen with dimensions of 80mm×10mm×4mm. Each group should produce at least one strip-shaped test specimen. Use a notch-making machine to process a V-shaped notch with a depth of 2mm and a bottom radius of 0.25mm in the middle of the specimen. Use a cantilever beam impact testing machine to perform impact tests on the notched specimens. Read the impact energy absorbed when the specimen breaks. Divide this energy value by the remaining cross-sectional area at the notch to calculate the cantilever beam notched impact strength of each group of specimens. Record the unit as kJ / m. 2 .

[0079] 3. Weigh 8.00g of each group of dried raw materials and place them in a melt flow rate tester to test their melt flow properties. Set the barrel test temperature to 315℃ and the test load to 5.0kg. After the barrel temperature stabilizes and the raw materials are preheated and melted in the barrel for 5 minutes, start the piston to apply the load and extrude the melt. Use an automatic cutter to cut the extrudate every 5 seconds, collect 5 consecutively cut extrudate strips without bubbles, and weigh their total mass. Based on the total cutting time and the total mass of the collected strips, calculate the melt outflow mass within 10 minutes. Record this calculated value as the melt flow rate test result, with the unit being g / 10min.

[0080] 4. Weigh 6.0 mg of each group of dried raw materials, place them in an aluminum crucible, press them into tablets, seal the tablets, and place them in a differential scanning calorimeter. Under a high-purity nitrogen atmosphere of 50 mL / min, raise the temperature to 320℃ at a rate of 20℃ / min and hold it at that temperature for 5 minutes; then cool it down to 150℃ at a cooling rate of 10℃ / min. Extract the heat flow curve during the cooling process, find the exothermic peak of crystallization on the heat flow curve, extract the temperature coordinate value corresponding to the peak of the exothermic peak, and record this temperature value as the crystallization peak temperature in ℃.

[0081] The experimental results are shown in Table 3: Table 3: Test results of mechanical, flow and crystallization properties for each test group

[0082] Test conclusion: According to the data in Table 3, in Comparative Example 1, all materials and additives were added to the extruder at once through the main feed port, and its cantilever beam notched impact strength was 4.1 kJ / m. 2 The melt flow rate was 92.4 g / 10 min, and the crystallization peak temperature was 223.5 °C. Compared with Examples 1 to 3, the cantilever beam notched impact strength and crystallization peak temperature of Comparative Example 1 were lower, while the melt flow rate was higher. This indicates that the cantilever beam notched impact strength and crystallization peak temperature of the material obtained under the one-time main feeding method were lower than those of Examples 1 to 3, while the melt flow rate was higher.

[0083] Comparative Example 5 combines the devolatilization and acid adjustment process with the nucleating agent addition process at the same feed inlet on one side, and its cantilever beam notched impact strength is 9.7 kJ / m. 2 The crystallization peak temperature was 228.4℃. Compared with Example 1, the cantilever beam notched impact strength and crystallization peak temperature of Comparative Example 5 were both lower, indicating that after the acid-adjusting component and the composite nucleating masterbatch were added at the same position, the impact performance and crystallization peak temperature of the resulting material were lower than those of Example 1.

[0084] Examples 1 to 3, by controlling the feeding sequence of premixing in the front stage, acid adjustment in the middle stage, and side feeding of composite nucleating masterbatch in the rear stage, achieved melt flow rates of 31.2 to 58.1 g / 10 min, crystallization peak temperatures of 235.8 to 248.3 °C, and cantilever beam notched impact strengths of 8.5 to 13.8 kJ / m². 2 Compared with Comparative Example 1, the cantilever beam notched impact strength and crystallization peak temperature of Examples 1 to 3 were higher, while the melt flow rate was lower; compared with Comparative Example 5, the crystallization peak temperature of Examples 1 to 3 was higher. These results indicate that the end-face sealing strip raw material prepared according to the feeding sequence described in the examples exhibits good overall performance in terms of mechanical, flow, and crystallization properties.

[0085] Test Example 4: Experimental steps: 1. The test objects were divided into three groups, specifically: Groups 1 to 3 used the modified end-face sealing strip raw materials prepared in Examples 1 to 3, respectively. The raw materials from Groups 1 to 3 were weighed and fed into an injection molding machine. Under the conditions of a barrel temperature of 320℃ and a mold temperature of 140℃, they were injection molded into annular end-face sealing strips with an outer diameter of 120mm, an inner diameter of 110mm, and a thickness of 5mm. These were used as the test objects for subsequent flatness, dimensional tolerance, and sealing leakage. At least two annular end-face sealing strips were prepared from each group, one for differential scanning calorimetry sampling, and the other for subsequent flatness, dimensional tolerance, and sealing leakage tests.

[0086] 2. A 5.0 mg sample was cut from the middle of the finished annular sealing strip (120 mm outer diameter) used for sampling in each group. The sample was placed in an aluminum crucible, sealed, and then placed in a differential scanning calorimeter. Under a high-purity nitrogen atmosphere (50 mL / min), the temperature was increased to 320 °C at a rate of 20 °C / min and held for 5 minutes for thermal history treatment, followed by a cooling rate of 10 °C / min. The crystallization enthalpy value on the cooling curve was extracted. After correcting this value according to the mass fraction of polyphenylene sulfide in the sample, it was divided by the theoretical melting enthalpy constant of 100% polyphenylene sulfide crystallization. The calculated percentage value was recorded as the crystallinity, with units recorded as . Subsequently, another 5.0 mg sample was taken from another location of the same sampled product. This sample was heated to 320°C and held at that temperature for 5 minutes using a differential scanning calorimeter. Then, it was rapidly cooled to 240°C at a rate of 50°C / min and held at that temperature. The time taken for the sample to reach 50% crystallinity during this isothermal crystallization process was recorded. The reciprocal of this time was recorded as the crystallization rate, with units of min. -1 .

[0087] 3. Using an injection molding machine at the same injection temperature of 320℃ and mold temperature of 140℃, the raw materials from the first to third groups were injection molded into dumbbell-shaped tensile specimens with dimensions of 150mm×10mm×4mm and elongated bending specimens with dimensions of 80mm×10mm×4mm, respectively. At least one dumbbell-shaped tensile specimen and one elongated bending specimen were prepared for each group. A universal testing machine was used to perform mechanical tests on the specimens. The crosshead movement speed for the tensile test was set to 5mm / min. The maximum tensile load value at the point of tensile fracture was extracted. This load value was divided by the initial cross-sectional area of ​​the narrow middle section of the dumbbell-shaped specimen, and the calculated stress value was recorded as the tensile strength, with the unit recorded as MPa. The gauge length elongation at fracture was extracted. This elongation was divided by the initial gauge length, and the calculated ratio was recorded as the elongation at break, with the unit recorded as [missing value]. The loading speed for the bending test was set to 2 mm / min. The slope value of the initial straight line segment on the bending stress-strain curve was extracted and recorded as the bending modulus in GPa.

[0088] 4. The dimensional accuracy of a complete circular end-face sealing strip with an outer diameter of 120mm, an inner diameter of 110mm, and a thickness of 5mm was tested using a coordinate measuring machine (CMM). The finished product was placed horizontally on the measuring platform, and 36 spatial coordinate points were evenly collected on the upper surface of the sealing strip using a probe. The CMM's data analysis software was used to perform least-squares fitting on these 36 points to generate an ideal plane. The maximum spatial distance value of all measured points deviating from this ideal plane was extracted and recorded as the flatness error in mm. The actual outer diameter of the sealing strip was measured using the CMM probe, and the design nominal outer diameter of 120.000mm was subtracted from the actual outer diameter. The maximum positive deviation value and the maximum negative deviation value were recorded and recorded as the dimensional tolerance in mm.

[0089] 5. Assemble each set of complete annular end-face sealing strips with an outer diameter of 120mm, an inner diameter of 110mm, and a thickness of 5mm into a simulated scroll compressor test bench. Set the internal operating temperature of the test bench to 120℃ and maintain the internal pressure of the test chamber at 0.8MPa. Start the test bench and run it continuously for 5000 hours. Use a gas flow meter to continuously monitor the gas leakage flow through the end face of the sealing strip during the operation. Extract the maximum daily average gas leakage flow during the 5000-hour operation cycle and record this maximum value as the sealing leakage amount, with the unit being m³. 3 / h.

[0090] The experimental results are shown in Table 4: Table 4: Performance Test Results of End Face Sealing Strips for Each Test Group

[0091] Test conclusion: According to the data in Table 4, the finished end-face sealing strips of Examples 1 to 3 exhibit corresponding crystallization properties, mechanical properties, dimensional accuracy, and sealing leakage data. Taking Example 1 as an example, the crystallization rate of its test sample is 0.86 min. -1 The crystallinity is 83.4%.

[0092] Correspondingly, the tensile strength of the injection-molded dumbbell-shaped specimen and the flexural modulus of the elongated specimen were 158.3 MPa and 8.6 GPa, respectively, with an elongation at break of 3.2%. In the finished product test of the annular end-face sealing strip, the flatness error of the finished product of Example 1 was 0.008 mm, and the dimensional tolerance was ±0.015 mm. Under the conditions of a set temperature of 120℃, a test chamber pressure of 0.8 MPa, and continuous operation for 5000 hours, the sealing leakage of the finished product of Example 1 was recorded as 0.04 m³. 3 / h. The crystallinity of Examples 2 and 3 were 79.1% and 81.6%, respectively; the tensile strengths were 145.6 MPa and 152.1 MPa, respectively; the flexural modulus was 8.1 GPa and 8.4 GPa, respectively; the flatness errors were 0.012 mm and 0.010 mm, respectively; the dimensional tolerances were ±0.021 mm and ±0.018 mm, respectively; and the sealing leakage was 0.06 m³, respectively. 3 / h and 0.05m 3 / h.

[0093] The above results show that the end-face sealing strips obtained in Examples 1 to 3 all have corresponding dimensional retention and end-face sealing performance under the set test conditions, among which the crystallinity, mechanical properties, dimensional accuracy and sealing leakage data of Example 1 are relatively superior.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for modifying and preparing raw materials for end face sealing strips of scroll compressors, characterized in that, The raw materials used in the modified preparation method, by weight, include the following components: polyphenylene sulfide: 100 parts, inorganic silica fume: 5-15 parts, maleic anhydride: 0.5-1.5 parts, pyromellitic dianhydride: 0.03-0.30 parts, triglycidyl isocyanate: 0.10-0.80 parts, polycarbodiimide: 0.10-0.60 parts, synthetic hydrotalcite: 0.20-1.20 parts, composite nucleating masterbatch: 3.5-9.5 parts, and alkali-free glass fiber: 20-45 parts; The modified preparation method includes the following steps: S1. The polyphenylene sulfide, the inorganic silica fume, the maleic anhydride, the pyromellitic dianhydride and the triglycidyl isocyanate are mixed and added to the front section of a twin-screw extruder, and then melt-mixed to obtain a premixed melt. S2. The premixed melt is conveyed to the middle section of the twin-screw extruder, and the vacuum exhaust port is opened for devolatilization treatment. Then, the polycarbodiimide and the pre-dried synthetic hydrotalcite are added from the side feed port and mixed to obtain the treated melt. S3. The processed melt is conveyed to the rear section of the twin-screw extruder, and the composite nucleating masterbatch and the alkali-free glass fiber are added from the side feed port. After mixing and extrusion, the modified extruded strip is obtained. S4. The modified extruded strip is cooled in a water-cooling tank and then granulated to obtain the modified end-face sealing strip raw material.

2. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 1, characterized in that, The raw materials, by weight, consist of the following components: polyphenylene sulfide: 100 parts, inorganic silica fume: 10 parts, maleic anhydride: 1 part, pyromellitic dianhydride: 0.15 parts, triglycidyl isocyanurate: 0.40 parts, polycarbodiimide: 0.30 parts, synthetic hydrotalcite: 0.60 parts, composite nucleating masterbatch: 6 parts, and alkali-free glass fiber: 35 parts.

3. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 1, characterized in that, In step S1, the mixing time is 3-8 minutes, the temperature of the front section of the twin-screw extruder is set to 290-310℃, and the screw speed of the twin-screw extruder is 300-450 rpm.

4. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 1, characterized in that, In step S2, the vacuum degree of the devolatilization treatment is controlled at -0.06MPa to -0.09MPa, the pre-drying temperature is 110-130℃, and after adding the polycarbodiimide and the synthetic hydrotalcite, they are mixed at 300-310℃ for 20-60 seconds.

5. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 1, characterized in that, In step S3, the temperature from the rear section of the twin-screw extruder to the die head of the twin-screw extruder is set to 315-330℃.

6. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 1, characterized in that, The preparation method of the composite nucleating masterbatch includes the following steps: Step 1: Add hexagonal boron nitride to a mixed solvent consisting of anhydrous ethanol and water, and sonicate to obtain a hexagonal boron nitride dispersion. Step 2: Add pimelic acid and calcium hydroxide sequentially to the hexagonal boron nitride dispersion, raise the temperature and stir the reaction to obtain a sedimentation suspension; Step 3: Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the deposition suspension, maintain the temperature and continue stirring to obtain the treatment suspension; Step 4: The treated suspension is filtered to separate solid and liquid components, washed with water, placed in a vacuum drying oven for drying, and then pulverized and sieved to obtain the composite nucleating mother powder.

7. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 6, characterized in that, The raw materials for preparing the composite nucleating masterbatch include, by weight, the following: The hexagonal boron nitride comprises 3-8 parts, the mixed solvent comprises 30-80 parts, the pimelic acid comprises 0.15-0.60 parts, the calcium hydroxide comprises 0.07-0.28 parts, and the γ-(2,3-epoxypropoxy)propyltrimethoxysilane comprises 0.10-0.80 parts; wherein the volume ratio of anhydrous ethanol to water in the mixed solvent is 1:

1.

8. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 6, characterized in that, In step 1, the ultrasonic treatment time is 30-60 minutes; in step 2, the target temperature for raising the temperature is 60-80℃, the stirring speed is 300-500 rpm, and the stirring time is 1-3 hours.

9. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 6, characterized in that, In step 3, the specific temperature for maintaining the temperature is 60-80℃, the stirring speed is 300-500 rpm, and the stirring time is 0.5-1 hour; in step 4, the drying temperature is 110-130℃, the drying time is 4-6 hours, and the sieve mesh size for pulverizing and sieving is 270-330 mesh.

10. The method for preparing modified raw materials for the end face sealing strip of a scroll compressor according to claim 1, characterized in that, The twin-screw extruder is a co-rotating parallel twin-screw extruder. The barrel of the twin-screw extruder is sequentially provided with a main feed port, zone 1, zone 2, zone 3, zone 4, zone 5, zone 6, zone 7, zone 8, and a die head along the material conveying direction. The machine head comprises the following sections: Zone 1, Zone 2, and Zone 3 constitute the front section, with a high-shear kneading block configured inside; Zone 4 and Zone 5 constitute the middle section, with a vacuum exhaust port configured in Zone 4 and a side feed port configured in Zone 5; Zones 6, 7, and 8 constitute the rear section, with a low-shear conveying threaded element configured inside; and a side feed port configured in Zone 6. A homogenization zone is configured inside the machine head.

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