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CN-122011648-A - Low-abrasion PTFE-based sealing element and preparation method thereof

CN122011648ACN 122011648 ACN122011648 ACN 122011648ACN-122011648-A

Abstract

The invention discloses a PTFE-based sealing element with low abrasion and a preparation method thereof, which belong to the technical field of PTFE-based material preparation and are used for solving the technical problems that the sealing performance and the low abrasion performance of the PTFE-based sealing element in the prior art are to be further improved; according to the invention, the reversible connection structure is introduced at the particle level, the interface coupling and bridging unit is built at the lamellar layer level, and the dynamic thioether network skeleton is embedded in the continuous phase, so that a multilayer structure system from point to surface to body is formed, and the structure participates in force transmission, interface regulation and control and deformation constraint in the forming and running processes, so that the material presents a cooperative optimization trend in friction and wear, thermal-force coupling stability and gas barrier behavior, and the comprehensive performance improvement brought by the integral structure construction is embodied.

Inventors

  • YAN BO
  • WANG XU

Assignees

  • 山东纳威尔密封件有限公司

Dates

Publication Date
20260512
Application Date
20260327

Claims (8)

  1. 1. A low-abrasion PTFE-based sealing element is characterized by comprising the following raw materials, by weight, 80-85 parts of reversible cross-linked PTFE particles, 8-12 parts of fluorine arylate-boron nitrogen bridged graphene, 8-10 parts of dynamic thioether network skeleton, 1-2 parts of polyvinyl alcohol, 1-2 parts of dioctyl phthalate and 0.2-0.4 part of 2, 6-di-tert-butylhydroquinone; The preparation method of the reversible cross-linked PTFE particles comprises the steps of adding furan grafted PTFE particles, 4 '-bismaleimide diphenylmethane and N-methyl-2-pyrrolidone into a reaction kettle, stirring until the materials are uniformly dispersed, heating the reaction kettle to 140-150 ℃, carrying out heat preservation and stirring for 5-6 hours, and carrying out post-treatment to obtain the reversible cross-linked PTFE particles, wherein the dosage ratio of the furan grafted PTFE particles, the 4,4' -bismaleimide diphenylmethane and the N-methyl-2-pyrrolidone is 20g:4-5g:160mL.
  2. 2. The low wear PTFE-based seal of claim 1, wherein said furan grafted PTFE particles are prepared by a process comprising: A1, adding polytetrafluoroethylene powder, sodium, naphthalene and tetrahydrofuran into a reaction kettle, introducing nitrogen for protection, and performing aftertreatment to obtain activated PTFE particles; A2, adding the activated PTFE particles, 2-tetrahydrofuranyl alcohol methacrylate, azodiisobutyronitrile and N, N-dimethylformamide into a reaction kettle, stirring until the mixture is uniformly dispersed, heating the reaction kettle to 60-70 ℃, stirring at the temperature of between 3 and 4 hours, filtering and collecting a filter cake after the reaction is finished, and washing and drying the filter cake to obtain the furan grafted PTFE particles.
  3. 3. The low wear PTFE-based seal of claim 2, wherein the amount of polytetrafluoroethylene powder, sodium, naphthalene and tetrahydrofuran used in step A1 is 20-24g:1-2g:2-3g:200ml, and the amount of activated PTFE particles, 2-tetrahydrofuranol methacrylate, azobisisobutyronitrile and N, N-dimethylformamide used in step A2 is 20g:10-12ml:0.8-1.2g:180ml.
  4. 4. The low-wear PTFE-based sealing element according to claim 1, wherein the dynamic thioether network material is prepared by adding 1, 4-benzenedithiol, 4 '-difluorodiphenyl sulfone, 4' -thiodiphenyl mercaptan, cesium carbonate and N-methyl-2-pyrrolidone into a reaction kettle, heating the reaction kettle to 100-110 ℃, preserving heat and stirring for 4-5h, and performing post-treatment to obtain the dynamic thioether network skeleton.
  5. 5. The low wear PTFE-based seal of claim 4, wherein the 1, 4-benzenedithiol, 4 '-difluorodiphenyl sulfone, 4' -thiodiphenyl thiol, cesium carbonate and N-methyl-2-pyrrolidone are used in a ratio of 6-8g:10-12g:3-4g:8-10g:150ml in the preparation of the dynamic thioether network backbone.
  6. 6. The low wear PTFE-based seal of claim 1, wherein the fluoroaryl-boron nitrogen bridged graphene is prepared by: adding graphene oxide and deionized water into a reaction kettle, uniformly stirring, adding 4-fluoroaniline and 10wt% hydrochloric acid aqueous solution, stirring in an ice bath, adding sodium nitrite in ten batches in equal quantity, heating the reaction kettle to 20-25 ℃ after the addition, keeping the temperature, stirring for 3-4 hours, and performing aftertreatment to obtain fluoroaryl graphene oxide; And B2, adding the fluoroaryl graphene oxide, 3- (aminopropyl) triethoxysilane and anhydrous toluene into a reaction kettle, stirring until the materials are uniformly dispersed, heating the reaction kettle to 75-85 ℃, stirring for 1-2 hours at a constant temperature, adding boric acid, continuing to perform a heat-preserving reaction for 2-3 hours, and performing post-treatment to obtain the fluoroaryl-boron-nitrogen bridged graphene.
  7. 7. The low wear PTFE based seal of claim 6, wherein in step B1, the graphene oxide, deionized water, 4-fluoroaniline, and 10wt% aqueous hydrochloric acid and sodium nitrite are used in a ratio of 5-6g:500ml:4-5g:15-20ml:4-5g, and in step B2, the fluoroarylated graphene oxide, 3- (aminopropyl) triethoxysilane, anhydrous toluene, and boric acid are used in a ratio of 5g:8-10ml:150ml:4g.
  8. 8. A method of making a low wear PTFE based seal according to any of claims 1-7, comprising the steps of: S1, adding reversible crosslinked PTFE particles, fluoroaryl-boron nitrogen bridged graphene, a dynamic thioether network skeleton, polyvinyl alcohol, dioctyl phthalate and 2, 6-di-tert-butylhydroquinone into a mixer, and uniformly mixing to obtain composite sealing material powder; s2, adding the composite sealing material powder into a die, hot-pressing for 20-30min at 320-340 ℃ and 15-25MPa, and demoulding to obtain the PTFE-based sealing element.

Description

Low-abrasion PTFE-based sealing element and preparation method thereof Technical Field The invention relates to the technical field of PTFE-based material preparation, in particular to a PTFE-based sealing element with low abrasion and a preparation method thereof. Background Polytetrafluoroethylene (PTFE) is widely used in gaskets, annular seals and valve seal structures in the fluid seal field due to regular molecular chains, low surface energy and outstanding chemical inertness, while pure PTFE materials are susceptible to molecular chain slippage, cold flow deformation and surface layer abrasion accumulation under the long-term friction and load coupling effects, thereby causing dimensional stability changes and interface bonding state fluctuation. Under the working condition of high-pressure gas or high-frequency opening and closing, the structural evolution is more remarkable, the abrasion rate is possibly increased, the sealing reliability is possibly fluctuated, the PTFE is generally subjected to structural regulation and control in the industry in a filling reinforcing, blending modifying or surface modifying mode and the like for improving the service performance of the PTFE, but different modifying paths still have differences in the aspects of dispersion uniformity, interface bonding efficiency and long-term stability, so that the structural optimization and system construction of the PTFE-based sealing element with low abrasion are continuously an important research direction in the field of sealing materials. At present, a PTFE-based sealing element adopts a physical filling or simple blending modification mode to improve the wear resistance, but the dispersion state and the interface bonding degree of the filler in a matrix are limited, interfacial deintercalation or particle peeling easily occurs under the action of friction load, so that a material removing mode is mainly based on brittle abrasion, a contact interface shearing path is unstable, meanwhile, particles mainly depend on physical compaction to form a bonding structure, the continuous constraint on an interface connection state is lacking, and microscopic damage accumulation and surface layer structural damage easily occur under the repeated start-stop or alternating load conditions. In addition, under the thermal-force coupling environment, the traditional PTFE material is influenced by molecular chain sliding and cold flow effects, the internal force transmission path of the continuous phase is easy to reorder and interrupt, local area deformation is difficult to effectively regulate and control, the filler is in an isolated and dispersed state, a through structural support or a planar limiting structure is difficult to form, the chain segment movement inhibition effect under the high-temperature condition is limited, and in addition, the structural constraint on microscopic clearance evolution and a gas migration path is lacking in the material, so that under the high-pressure gas sealing working condition, a lifting space still exists for tissue compactness and long-term stability. In view of the technical drawbacks of this aspect, a solution is now proposed. Disclosure of Invention The invention aims to provide a PTFE-based sealing element with low abrasion and a preparation method thereof, which are used for solving the technical problems that the sealing performance and the low abrasion performance of the PTFE-based sealing element in the prior art are required to be further improved. The low-abrasion PTFE-based sealing piece comprises the following raw materials, by weight, 80-85 parts of reversible cross-linked PTFE particles, 8-12 parts of fluoroaryl-boron nitrogen bridged graphene, 8-10 parts of dynamic thioether network skeleton, 1-2 parts of polyvinyl alcohol, 1-2 parts of dioctyl phthalate and 0.2-0.4 part of 2, 6-di-tert-butylhydroquinone; The preparation method of the reversible cross-linked PTFE particles comprises the steps of adding furan grafted PTFE particles, 4' -bismaleimide diphenylmethane and N-methyl-2-pyrrolidone into a reaction kettle, stirring until the mixture is uniformly dispersed, heating the reaction kettle to 140-150 ℃, keeping the temperature, stirring for 5-6 hours, and performing post treatment to obtain the reversible cross-linked PTFE particles. Further, the dosage ratio of the furan grafted PTFE particles to the 4,4' -bismaleimide diphenylmethane to the N-methyl-2-pyrrolidone is 20g:4-5g:160mL, the post-treatment comprises cooling to room temperature after the reaction is finished, filtering, collecting the solid, washing and drying to obtain the reversible crosslinked PTFE particles. Further, the furan grafted PTFE particles are prepared by the following method: A1, adding polytetrafluoroethylene powder, sodium, naphthalene and tetrahydrofuran into a reaction kettle, introducing nitrogen for protection, and performing aftertreatment to obtain activated PTFE particles; A2, adding the activa