Method for sintering polytetrafluoroethylene

Abstract

The invention provides a method for sintering a polytetrafluoroethylene sealing ring. The invention employs a sintering furnace which comprises a sintering furnace body, a nitrogen conveying device and a program control device. The sintering furnace body comprises four zones such as a drying zone (2), a preheating zone (3), a sintering zone (4) and a cooling zone (5). The method comprises the following steps: (1) preparing polytetrafluoroethylene stock;(2)drying polytetrafluoroethylene stock in the drying zone; (3) preheating stock in the preheating zone; (4) sintering stock in sintering zone; (5)cooling. According to the invention, the sintering sealing effect and automatic control can be enhanced for effectively inhibiting the escape of hydrogen fluoride during the sintering process, metal powder modified materials filled in polytetrafluoroethylene is avoided an oxidation generated by contacting with air in a high temperature through a heat nitrogen cycle, thereby the usage performance and the appearance of the products can be improved.

Description

technical field [0001] The invention relates to the technical field of chemistry and chemical engineering, in particular to a method for sintering polytetrafluoroethylene. Background technique [0002] Polytetrafluoroethylene (PTFE) has excellent chemical stability, corrosion resistance, sealing, high lubrication and non-stickiness, electrical insulation and good aging resistance, and excellent temperature resistance (can be used at +250°C to -180°C Long-term work at high temperature), but its fluidity is poor, it is easy to decompose, and it is a polymer material that generates corrosive gas when decomposed. In the molding process, the temperature must be strictly controlled. If the temperature is not properly controlled, hydrogen fluoride will decompose and escape, causing poisoning of animals and humans within 2 square kilometers. At present, the recycling technology of polytetrafluoroethylene is not yet mature, and it is generally formed at one time, so there is no room...

AI Technical Summary

Problems solved by technology

The difference in process conditions such as sintering temperature and cooling rate directly affects the molecular weight, crystallinity and porosity of the product, and these three affect the physical, mechanical and electrical properties of the product. At the same time, the completion of the sintering process also affects the product. The size and distribution of residual stress in the product, so the improper control of the sintering process will lead to warping, deformation and even cracking of the product, which will lead to severe toxicity and pollute the environment

In addition, pure PTFE is not wear-resistant and easy to creep; generally, it needs to be modified by filling. At present, the modified material used in large quantities is metal powder modification; metal powder will be oxidized at high temperature, which will affect the performance and appearance of the product. ; Generally, it will be removed during processing, which can only increase the processing allowance of the product, which will cause a large waste

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