Extrusion die for screw thread inner wall and method of improving fibrosis degree of thin film charge bar

Abstract

The invention provides an extrusion die for screw thread inner walls and a method of improving fibrosis degree of thin film charge bars. The extrusion die comprises a die body, wherein a conical holecavity and an extrusion hole are arranged in the die body. A small diameter end of the conical hole cavity is communicated with the extrusion hole, and screw threads are arranged on the inner wall ofthe conical hole cavity. According to the extrusion die for the screw thread inner walls, the screw threads are arranged on the inner wall of the conical hole cavity, the shear friction between powderparticles and the inner wall of the die can be effectively improved in the process of plunger type extrusion of PTFE, so that the fibrosis degree of the charge bars is significantly improved. And dueto a guiding role of the screw thread, the action direction of the shear force is always parallel to the direction of the screw thread, corresponding generated micro fiber will orient along the direction of the screw thread, and fibrosis direction is more accurate, therefore the quality uniformity and mechanical stability of the final produced PTFE thin film are ensured. The CV value of the thickness uniformity of the PTFE thin film produced by general mold is 30-50%, while the thickness uniformity CV value of the PTFE thin film prepared by the extrusion die for the screw thread inner wallsand the method of improving fibrosis degree of the thin film charge bars can reach less than 10%.

Description

technical field [0001] The invention belongs to the technical field of moulds, and in particular relates to a threaded inner wall extrusion die and a method for improving the fiberization degree of a film material rod. Background technique [0002] With its many advantages, polytetrafluoroethylene (PTFE) is being widely used in aerospace, petrochemical, electronics, medicine and other fields. For PTFE, because of its high viscoelasticity, if it is processed by screw extrusion, the performance of the product will be greatly affected. Therefore, most of the continuously produced PTFE products are processed by plunger extrusion. In the production process of the traditional PTFE breathable film, the extrusion process of the PTFE body generally uses a mold with a smooth inner wall, and then the PTFE microporous membrane is produced according to processes such as calendering, biaxial stretching, heat treatment and horizontal stretching. , the process flow is: [0003] PTFE resin...

AI Technical Summary

Problems solved by technology

[0004] There are two disadvantages in the extrusion process of PTFE film processed by traditional technology. One is that the degree of fibrosis of the rod after extrusion is low, and the other is that the direction of fibrillation is more chaotic.

The above two defects make it difficult to guarantee the mechanical properties and uniformity of the final PTFE film

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