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CN-121975153-A - Preparation method of polyimide granule capable of being molded by injection

CN121975153ACN 121975153 ACN121975153 ACN 121975153ACN-121975153-A

Abstract

The invention discloses a preparation method of polyimide particles capable of being injection molded, which comprises the steps of firstly dissolving diamine monomers in a polar solvent, then adding a blocking agent and dianhydride monomers, stirring and reacting to obtain a polyamic acid solution, then sequentially adding a poor solvent, a dehydrating agent and a catalyst, stirring to complete imidization, then carrying out suction filtration and washing for multiple times, and finally drying to obtain the polyimide particles capable of being injection molded. The polyimide prepared by the invention has higher Tg, the melting temperature is 320-340 ℃, the heat resistance and the processability of the product are both considered, in addition, the melt index is moderate, the polyimide can be directly injection molded without pelleting, the mechanical property of an injection molding part is good, and the polyimide is the thermoplastic polyimide with excellent comprehensive properties of heat resistance and processability and used for direct injection molding.

Inventors

  • HU JINPING
  • CHEN YI
  • QIU CHENGGANG

Assignees

  • 常州市尚科新材料有限公司

Dates

Publication Date
20260505
Application Date
20251229

Claims (10)

  1. 1. A process for the preparation of injection moldable polyimide particles characterized by the steps of: S1, dissolving diamine monomer 4, 4-bis (3-aminophenoxy) diphenylsulfone in a polar solvent in a low-speed shearing dispersing machine at the temperature of 15-25 ℃ and under the protection of nitrogen, then adding a mixture of a blocking agent and dianhydride monomer pyromellitic dianhydride, and stirring and reacting for 3-6 hours to obtain a polyamic acid solution; S2, adding a poor solvent into the polyamic acid solution obtained in the step S1, then adding a dehydrating agent, then adding a catalyst, stirring until regular elliptic particles slowly separate out from the solution, and then continuing stirring until the imidization process is completed in a low-speed shearing disperser at the temperature of 15-25 ℃ and under the protection of nitrogen; s3, carrying out suction filtration and washing on the material obtained in the step S2 for multiple times to obtain a wet product, and then carrying out low-temperature vacuum drying and high-temperature blast drying on the wet product to obtain the polyimide granule material capable of being subjected to injection molding.
  2. 2. The method of producing injection-moldable polyimide particles of claim 1, wherein the molar ratio of the diamine monomer to the dianhydride monomer in the step S1 is 1:1.
  3. 3. The method for preparing injection-moldable polyimide particles according to claim 1, wherein in the step S1, the end-capping agent is one of phthalic anhydride, tetrahydrophthalic anhydride and succinic anhydride, and the molar ratio of the end-capping agent to the diamine monomer is 0.05:1-0.15:1.
  4. 4. The method for preparing injection-moldable polyimide particles according to claim 1, wherein in the step S1, the polar solvent is one or more of DMF, DMAc, NMP, DMSO, and the solid content of the polyamic acid solution is 15-25%.
  5. 5. The method for producing polyimide particles according to claim 1, wherein in the step S1, the rotation speed of the low-speed shearing disperser is 50 to 150rpm, and in the step S2, the rotation speed of the low-speed shearing disperser is 180 to 220rpm.
  6. 6. The method for preparing injection-moldable polyimide particles according to claim 1, wherein in the step S2, the poor solvent is one or more of toluene, xylene, n-heptane and n-hexane, and the amount of the poor solvent is 0.5 to 1.5 times the amount of the polar solvent.
  7. 7. The method for preparing injection-moldable polyimide particles according to claim 1, wherein in the step S2, the dehydrating agent is one or more of acetic anhydride, propionic anhydride and trifluoroacetic anhydride, and the molar ratio of the dehydrating agent to the diamine monomer is 2:1-6:1.
  8. 8. The method for preparing injection-moldable polyimide particles according to claim 1, wherein in the step S2, the catalyst is one or more of triethylamine, pyridine, picoline, quinoline and isoquinoline, and the molar ratio of the catalyst to the diamine monomer is 1.5:1-3.0:1.
  9. 9. The method for preparing the injection-moldable polyimide particles according to claim 1, wherein in the step S3, the washing solvent is one or more of methanol, acetone, ethanol and purified water, the washing temperature is 25-60 ℃, the washing time is 1-3 h, and the amount of the washing solvent used in each washing is 4-8 times of the total weight of the monomers.
  10. 10. The method for producing polyimide particles according to claim 1, wherein in the step S3, the low-temperature vacuum drying is performed at 80℃C/2h to 120℃C/2h, and the high-temperature air-blast drying is performed at 160℃C/1h to 230℃C/1h to 250℃C/2h.

Description

Preparation method of polyimide granule capable of being molded by injection Technical Field The invention belongs to the technical field of polyimide, and particularly relates to a preparation method of polyimide particles capable of being injection molded. Background The aromatic polyimide has excellent heat resistance and mechanical property, and is widely applied to various fields of aerospace, weaponry, automobiles, electronic appliances and the like. However, since the main chain thereof has a structure containing a large amount of benzene heterocycles, the rigidity of the molecular chains is high, the forces between the molecular chains are large, and a high melt processing temperature is required for molding, many polyimides must be molded by coating film at the stage of the precursor polyamic acid thereof, or the high temperature molded product is processed into a desired shape by a machining form, and thus the processability is poor, resulting in limited applications in many fields. The injection molding process can realize continuous batch production and has short production period. Therefore, the polyimide which can be developed through injection molding has good application prospect. The polyimide which is available on the market at present is mainly Ultem from Sabic of Saudi basic industry and Aurum of Mitsui chemical of Japan. Ultem contains bisphenol A residues, has poor solvent resistance, tg of only 217 ℃ and use temperature of only 150-180 ℃, is a lower variety of polyimide used as engineering plastics, but has higher market competitiveness due to outstanding processability and low price compared with the traditional polyimide. The Aurum has excellent thermal stability in melting, is suitable for melt molding such as extrusion molding, injection molding and the like, has a Tg of 245 ℃, has heat resistance superior to Ultem, and has higher heat resistance in thermoplastic plastics, but expensive diamine is adopted for improving the heat resistance and processability of products, so that the production cost is high. Other studies on injection molding type polyimides are currently mostly carried out at the cost of reducing Tg by increasing the flexible groups, and the currently studied polyimides capable of achieving injection molding conditions generally have Tg less than 250 ℃ and are mostly present in powder form and require a granulation process prior to injection molding. Therefore, on the premise of keeping the excellent comprehensive performance of polyimide, developing injection-moldable polyimide with excellent processability and convenient operation becomes a new research hot spot. Disclosure of Invention The invention aims to solve the problems and provide a preparation method of polyimide particles capable of being molded. The technical scheme for realizing the aim of the invention is that the preparation method of the polyimide granule material capable of being injection molded comprises the following steps: S1, dissolving diamine monomer 4, 4-bis (3-aminophenoxy) diphenylsulfone (hereinafter referred to as m-BAPS) in a polar solvent in a low-speed shearing dispersing machine at the temperature of 15-25 ℃ and under the protection of nitrogen, adding a mixture of a blocking agent and dianhydride monomer pyromellitic dianhydride (hereinafter referred to as PMDA), and stirring and reacting for 3-6 hours to obtain a polyamic acid solution. S2, adding a poor solvent into the polyamic acid solution obtained in the step S1, then adding a dehydrating agent, then adding a catalyst, stirring until regular elliptic particles slowly separate out from the solution, and then continuing stirring until the imidization process is completed in a low-speed shearing disperser at the temperature of 15-25 ℃ and under the protection of nitrogen. S3, carrying out suction filtration and washing on the material obtained in the step S2 for multiple times to obtain a wet product, and then carrying out low-temperature vacuum drying and high-temperature blast drying on the wet product to obtain the polyimide granule material capable of being subjected to injection molding. In the step S1, the molar ratio of the diamine monomer to the dianhydride monomer is 1:1. In the step S1, the end capping agent is one of phthalic anhydride, tetrahydrophthalic anhydride and succinic anhydride, preferably phthalic anhydride, and the molar ratio of the end capping agent to the diamine monomer is 0.05:1-0.15:1. In the step S1, the polar solvent is one or more of DMF, DMAc, NMP, DMSO, and the solid content of the polyamic acid solution is 15-25%. In the steps S1 and S2, the cutter head adopted by the low-speed shearing dispersing machine is a 4-8 She Liti refined steel cutter head, the rotating speed of the low-speed shearing dispersing machine in the step S1 is 50-150 rpm, and the rotating speed of the low-speed shearing dispersing machine in the step S2 is 180-220 rpm. In the step S2, the poor solvent is one or more of tolu