PTFE, PFA, FEP, PVDF Fluoroplastic products industry experts
Production of expanded polytetrafluoroethylene
Classification:
Industry dynamics
Author:
PFA tube little sister
Source:
Dankai
Release time:
2022-12-17
Visits:
The formation of expanded polytetrafluoroethylene is divided into two stages. In the first stage, the PTFE bulk resin and the lubricant are mixed in a certain ratio. After a period of time, preforming, however
After drying and removing additives, the paste is extruded into a longitudinally arranged fiber preform; the second stage is high-speed stretching at a temperature below the melting point of PTFE, and then
The semi-finished polytetrafluoroethylene product in a highly stretched state is heat-set at the melting point temperature to obtain an expanded polytetrafluoroethylene product.
The process flow is as follows:
(1) Mixing Polytetrafluoroethylene resin and extrusion additives are uniformly mixed in a certain mass ratio. Choose a dispersing resin that has good fiber-forming properties and the internal
The cohesion is low, and the molecular chains are arranged along the long axis direction of the particle by a small shearing action to form a linear crystal. The addition of extrusion aids can increase the adhesion of the particles and reduce the tree.
Grease particles and the friction between the resin and the container, and improve the processing performance. The propellant may typically be petroleum ether, toluene, acetone, kerosene, paraffin, etc.
(2) Preforming The mixture is pressed into a blank having the same shape as the film chamber of the pusher.
(3) Push the billet into the film cavity of the pusher to push it, and obtain the rod at the pusher.
(4) Calender The calender is rolled to obtain a strip of the desired width and thickness.
(5) Drying The tape was heated and dried to remove the extrusion aid on the tape to obtain a polytetrafluoroethylene film.
(6) Expansion The polytetrafluoroethylene film is rapidly stretched, and the stretching temperature is controlled between the glass transition temperature (115) and the melting point (327) of the polytetrafluoroethylene. Because poly
The compound chains are sufficiently energetic at temperatures above the glass transition temperature that they can pull apart from irregular clusters and then move to each other. When the temperature is higher than the melting point
The PTFE particles have melted and become a dense whole, which destroys the folded shape of the original fiber bundle and is difficult to pull apart.
(7) Molding Put the expanded PTFE film on the template, and then put it in the mold towel, heat and pressurize, the molding process needs to be heated to melt at a certain heating rate
Point (327). Then, when it is kept at a certain temperature and a certain stress for a certain period of time, the network structure formed after stretching is determined. The process needs to be under certain pressure
and the fibers shrink during heat treatment.
Simple process flow diagram: (PTFE resin lubrication and extrusion agent dispersion) a preform mixture. Push Calendering-Drying-Expansion Type.
In the above method, the grade of PTFE resin, the stretching ratio, the heating rate and the heat-setting temperature are the main factors affecting the performance of the product.
This article is originally created by Teflon's little sister. Welcome to pay attention and take you to grow knowledge together!
Key words:
PTFE, resin, temperature, stretching, certain, extrusion, then, melting point, particles
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