Briefly describe the common
2020-08-24 16:47:34
First of all we have to know what is raw tape
Raw material tape, also known as water tape, raw tape, scientific name polytetrafluoroethylene tape, polytetrafluoroethylene is a polymer of tetrafluoroethylene, the English abbreviation is PTFE. Common white PTFE tapes are commonly used in HVAC and water supply and drainage, and there are special PTFE tapes for natural gas pipelines. In fact, the main raw materials are all PTFE, but some processes are different.
The raw material belt is produced with imported materials and advanced technology, with high quality and complete specifications, which can meet the requirements of different customers in different industries. PTFE raw material tape (PTFE raw material tape) is the residual deformation of the resin under the action of pressure. It is first made into rods or strips by pressing and molding, and then placed on a roller press Under the action of the roller pressure, it stretches into a thin strip with a certain thickness and width, and finally removes the extrusion aid to obtain a raw material strip.
application
Polytetrafluoroethylene can be formed by compression or extrusion processing; it can also be made into water dispersion for coating, impregnation or fiber. Polytetrafluoroethylene is widely used as high and low temperature resistant, corrosion resistant materials, insulating materials, anti-stick coatings, etc. in nuclear energy, aerospace, electronics, electrical, chemical, machinery, instruments, meters, construction, textiles, food and other industries.
Polytetrafluoroethylene is widely used in all kinds of acid and alkali resistance and organic solvents. It is not toxic to humans. However, one of the raw materials used in the production process, perfluorooctanoate (PFOA), is considered to have carcinogenic effects.
Main function: Expanded polytetrafluoroethylene raw material belt uses 100% polytetrafluoroethylene as raw material, which has a net-like expanded structure composed of fine long fibers and knots. Expanded PTFE raw material belt has the characteristics of good toughness, high longitudinal strength and easy deformation in the transverse direction. It is an ideal material for sealing on discs and threads. However, it cannot be used where it is in contact with high-concentration oxygen or liquid oxygen.
How to use raw material belt
1. The raw material tape needs to be wound along the thread direction, which greatly reduces the sealing performance;
2. Do not wrap all threads with raw material tape, otherwise the raw material tape will enter the pipe and reduce the sealing performance. We need to start winding from the second thread at the beginning of the thread and leave the first thread;
3. When winding the raw material tape, it is necessary to use a little force to ensure that the raw material tape is wound without being broken. The raw material tape wound in this way is tight and firm enough to ensure the tightness;
4. As for a few turns of the raw material tape, I believe that the master must have his own experience, but here I remind everyone that the thickness of the rear part of the wound raw material tape is thicker, that is, the front is thinner and the back is thicker. Make sure that the thread is more twisted. Tight, increase sealing performance;
5. After the raw material tape is wrapped, once the threaded pipe is tightened, do not unthread it, otherwise it needs to be re-wound and tightened;
Main features
Chemical nature
1. Insulation: Not affected by the environment and frequency, the volume resistance can reach 1018 ohm·cm, the dielectric loss is small, and the breakdown voltage is high.
2. High and low temperature resistance: little effect on temperature, wide temperature range, applicable temperature -190~260℃.
3. Self-lubricating: It has the smallest friction coefficient among plastics and is an ideal oil-free lubricating material.
4. The surface is not sticky: known solid materials can not adhere to the surface, it is a solid material with the smallest surface energy.
5. Atmospheric aging resistance, radiation resistance and low permeability: long-term exposure to the atmosphere, the surface and performance remain unchanged.
6. Corrosion resistance: chemical resistance and weather resistance. Except for molten alkali metals, PTFE is hardly corroded by any chemical reagents.
Physical properties
The mechanical properties of PTFE are relatively soft. Has very low surface energy.
1. Non-combustibility: The oxygen limit index is below 90.
2. Mechanical properties: Its friction coefficient is extremely small, only 1/5 of polyethylene, which is an important feature of perfluorocarbon surface. In addition, because the fluorine-carbon chain intermolecular force is extremely low, PTFE is non-sticky.
3. Temperature resistance: PTFE maintains excellent mechanical properties in a wide temperature range of -196～260℃. One of the characteristics of perfluorocarbon polymers is that they are not brittle at low temperatures.
4. Electrical properties: PTFE has low dielectric constant and dielectric loss in a wide frequency range, and has high breakdown voltage, volume resistivity and arc resistance.
5. Radiation resistance: PTFE has poor radiation resistance (104 rads). It will degrade after being exposed to high-energy radiation, and the electrical and mechanical properties of the polymer will decrease significantly.