A kind of manufacturing method of polytetrafluoroethylene small-caliber volumetric flask

Abstract

The invention discloses a method for manufacturing a polytetrafluoroethylene small-caliber volumetric flask. The method comprises the five following steps: molding, filling, demolding, sintering and cooling, wherein four processing stages, such as a low-temperature sintering stage, a medium-temperature sintering stage, a high-temperature sintering stage and a thermal insulation sintering stage, are set in the sintering period. Because the thermal conductivity of the polytetrafluoroethylene is only 0.251W / (m.K), the heat transfer is slow, and when the sintering temperature is reached, only the surface of the product is plasticized, and the inside sintering temperature is not reached, the product needs to be kept for a certain time under the specified sintering temperature, and the product is totally transparent. The volumetric flask is sintered in the four stages, and independent constant-temperature standing time is set at each sintering stage, so that the sintering temperature inside and outside the volumetric flask is uniform. Therefore, each part of the volumetric flask can be kept consistent at different stages, so that the manufacturing quality of the volumetric flask is improved, the occurrence rate of defective goods is reduced, the processing cost is saved, and the processing risk is reduced.

Description

technical field [0001] The invention relates to the technical field of volumetric flask manufacturing, in particular to a manufacturing method of a polytetrafluoroethylene small-diameter volumetric flask. Background technique [0002] Compression molding is currently one of the most commonly used methods for making volumetric flasks from polytetrafluoroethylene (PTFE). The compression molding process is a method in which certain molding materials (powder, pellets, fibrous materials, etc.) are put into a metal mold and formed under a certain temperature and pressure. The main characteristics of compression molding are low cost, simple equipment, low investment, and it is not affected by the defects of high molecular weight and extremely poor fluidity of the processed plastics. When other processing methods are immature, countries around the world mainly use compression molding. Molding to process PTFE products. [0003] When using polytetrafluoroethylene to make volumetric ...

AI Technical Summary

Problems solved by technology

Although each method is slightly different, they are indeed very similar in the sintering step, which is also one of the most difficult steps to control in the process. If the sintering is not good, the product will crack, defective products will appear, and even the whole process will be seriously affected. The products in the sintering furnace will further increase the loss; moreover, the temperature control is also very important, because if the temperature is too high, if it exceeds 420°C, polytetrafluoroethylene will decompose sharply at 415°C and emit toxicity. gas, producing perfluoroisobutylene gas, which makes the product and the production environment more toxic, which is not conducive to the protection of the environment and the health of the workers.

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