Cold flow fiber forming extrusion molding method and device for polytetrafluoroethylene film

A polytetrafluoroethylene film and extrusion molding technology, which is applied in the field of polytetrafluoroethylene film processing, can solve the problems of inconspicuous fiberization of polytetrafluoroethylene particles and the inability to realize continuous production, etc., to solve the problem of difficult feeding, Improve the fiber length and node density, improve the effect of product performance

Pending Publication Date: 2021-12-21
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Paste extrusion can process polytetrafluoroethylene resin into film, but due to the limitation of existing processing technology, it is still unable to realize continuous production. At the same time, the fiberization of polytetrafluoroethylene particles in the extrusion process is not obvious. Above, most of the PTFE fibers in the product are formed during the stretching process

Method used

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  • Cold flow fiber forming extrusion molding method and device for polytetrafluoroethylene film
  • Cold flow fiber forming extrusion molding method and device for polytetrafluoroethylene film
  • Cold flow fiber forming extrusion molding method and device for polytetrafluoroethylene film

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Embodiment 1

[0035] A kind of cold flow fiber forming extrusion molding device of polytetrafluoroethylene in this embodiment, such as figure 1 As shown, its main components include blade shaft 1, hopper 2, baffle plate 3, stator 4, blade 5, stretching module 6, sleeve 7, connecting seat 8 and die head 9, forming blades connected in sequence along the material conveying direction Conveying unit a and stretching unit b.

[0036]The specific structure of the blade conveying unit is: the stator and the baffle are placed in the front section of the sleeve, the stator is a multi-section structure, a baffle is arranged between any two adjacent stators, and the baffle extends from the inside of the stator to the inner cavity of the stator . There are multiple blades distributed on the cylindrical surface of the blade shaft. The blades are telescopically installed in the preset slots of the blade shaft. The blades are arranged in multiple groups. The same group of blades is located on the same axi...

Embodiment 2

[0040] This embodiment is a polytetrafluoroethylene cold-flow fiber-forming extrusion molding device. Compared with Embodiment 1, the difference lies in that the specific structure of the stretching unit is different.

[0041] Such as image 3 As shown, in this embodiment, the stretching unit adopts the form of coaxial assembly of the stretching shaft 11 and the stretching barrel 12 , the stretching shaft is in a spiral shape as a whole, and is fixed in the stretching barrel by the three-claw bracket 10 . Along the axial direction, the radial height of the stretching shaft decreases gradually, the inner diameter of the stretching barrel decreases gradually, and the flow channel volume of adjacent screw pitches gradually decreases. In the stretching runner, the PTFE resin advances helically along the pulling axis, due to the change of the axial space of the runner (such as Figure 4 As shown), under the action of tensile force, the PTFE resin particles will undergo the process...

Embodiment 3

[0043] This embodiment is a polytetrafluoroethylene cold-flow fiber-forming extrusion molding device. Compared with Embodiment 2, the difference lies in that the specific structures of the stretching shaft and the stretching barrel in the stretching unit are different.

[0044] Such as Figure 5 As shown, in this embodiment, along the axial direction, the inner diameter of the stretching barrel remains unchanged, and the radial height of the stretching shaft also remains constant, but the pitch of the stretching shaft decreases gradually, so that the flow channel volume of adjacent pitches slowing shrieking. In addition, according to the actual needs of polymer material melt extrusion-flow / calendering, the radial section of the stretching unit can also adopt other shapes.

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Abstract

The invention discloses cold flow fiber forming extrusion molding method and device for a polytetrafluoroethylene film. The method comprises the following steps that, firstly, a material is conveyed into a stretching unit by utilizing a blade conveying unit with positive displacement conveying characteristics; then, by utilizing the change of the radial cross-sectional area or / and the radial cross-sectional shape of a stretching runner in the stretching unit, a stretching assembly generates stretching acting force on the passing material, and the material is promoted to be gradually flattened and then fiberized; and finally extrusion molding is performed to obtain a polytetrafluoroethylene film. The device comprises a blade conveying unit, a stretching unit and a die head which are sequentially connected in the material conveying direction, a conveying runner in the blade conveying unit, the stretching runner in the stretching unit and a forming runner in the die head are sequentially communicated, and the radial section area or / and the radial section shape of the stretching runner in the stretching unit are / is in a changing state. According to the method, fiber length and node density of polytetrafluoroethylene can be effectively improved, the product performance is improved, and continuous production is realized.

Description

technical field [0001] The invention relates to the technical field of polytetrafluoroethylene film processing, in particular to a cold-flow fiber-forming extrusion molding method and device for polytetrafluoroethylene film. Background technique [0002] Polytetrafluoroethylene (PTFE) membrane has excellent chemical stability, high heat resistance, super high hydrophobicity and high fracture toughness, and is widely used in filtration, biomedicine, heat insulation, sealing and other fields. The highly helical symmetrical molecular chain structure not only brings excellent performance to PTFE, but also gives PTFE difficult to process. High crystallinity (generally 90%-96%) leads to high melting temperature (380°C) and high melt viscosity (10 10 Pa S), so polytetrafluoroethylene cannot be processed into products by melt extrusion. The high bond energy (up to 485KJ / mol) of the C-F bond makes polytetrafluoroethylene difficult to dissolve in various solvents. At the same time,...

Claims

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Application Information

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IPC IPC(8): B29C48/05B29C48/285B29C48/80B29C48/25
CPCB29C48/05B29C48/285B29C48/802B29C48/0018B29C48/267
Inventor 张桂珍尹剑锋
Owner SOUTH CHINA UNIV OF TECH
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