1. Composition and characteristics of PTFE tape
PTFE tape, also known as polytetrafluoroethylene tape, is a high-performance synthetic material. It has excellent high temperature resistance, chemical corrosion resistance, non-stickiness and good mechanical properties. Therefore, PTFE tape is widely used in various industrial fields, such as chemical, electronics, food processing, etc.

2. Shelf life of PTFE tape
Whether PTFE tape will expire depends mainly on its storage conditions and use environment. Under ideal storage conditions, the shelf life of PTFE tape can usually reach several years or even longer. However, if the storage conditions are not good, such as exposure to sunlight, high temperature environment or humid environment, the performance of PTFE tape may be affected, thereby shortening its service life.

3. How to judge whether PTFE tape is expired
1. Appearance inspection: If cracks, discoloration or deformation appear on the surface of PTFE tape, it may mean that the tape has expired or its performance has deteriorated.
2. Performance test: Some simple tests can be used to determine whether the performance of PTFE tape has changed, such as viscosity test, high temperature resistance test, etc. If the performance of the tape is found to be significantly reduced, it may mean that the tape has expired.
3. Use environment: If the PTFE tape has abnormalities during use, such as reduced viscosity, reduced high temperature resistance, etc., it may mean that the tape has expired or is no longer suitable for the current use environment.

IV. Conclusion
Whether PTFE tape will expire depends mainly on its storage conditions and use environment. Under ideal storage conditions, the shelf life of PTFE tape can usually reach several years or even longer. However, if the storage conditions are poor or the use environment is harsh, the performance of PTFE tape may be affected, thereby shortening its service life. Therefore, in order to ensure the performance and safety of PTFE tape, it is recommended to check the condition of the tape regularly and replace it or adjust the use environment according to the actual situation.