Study On Key Technologies Of Preparing Polytetrafluoroethylene Porous Membrane

Polytetrafluoroethylene microporous membrane prepared by biaxial stretching process,with a staggered microstructure of the fiber to form a certain shape and size of the pore size,and high porosity,therefore,it has excellent filtration performance,good ventilation and can be retained dust particles,is widely used in air filtration,pharmaceutical food filtration,clothing fabrics and other fields.Based on the combination of the theoretical methods of PTFE performance,processing and film application and the practical experience of the industry for many years,this paper focuses on several key technologies in the PTFE biaxial stretching process,the research ideas of the theoretical method,technology,equipment and technology are discussed in depthFirst,this paper will introduce the theoretical methods of PTFE performance,processing and membrane application,which will provide theoretical guidance for the key technology research of PTFE microporous membrane.Second,this paper will study the key process and equipment in the preparation of PTFE biaxial stretch film,including:mixing process and equipment research,and an optimized hybrid method is proposed.The advantages and disadvantages of the shape of circular,flat and rectangular extruded die are analyzed in the research of prepress extrusion process and equipment.In the study of calendering process and equipment,the precision and stability of the calender are improved through the application of static bearing and the optimization of the guide plate.In the study.of longitudinal drawing process and equipment,the design of longitudinal drawing roller and longitudinal pull rate is emphasized.In the study of horizontal pull process and equipment,the method of cooling the chain clamp was improved,and the air volume and the tensile force of the film were simulated by the finite element analysis method.Then,the effect of different process parameters on the performance of PTFE film was studied,including:material selection,the influence of the molecular weight of PTFE powder on the pore diameter and membrane strength of PTFE powder was studied.The influence of pressure value and die compression ratio on film aperture and permeability was studied.The influence of tensile rate,stretch ratio and tensile temperature on the pore diameter and permeability was studied.The influence of transverse pull rate,transverse pull rate,transverse pull temperature and thermosetting temperature on film aperture,permeability,film strength and tensile uniformity were studied.Finally,based on the key technology of PTFE microporous membrane preparation research,try to solve the following two questions:at the same time improve the strength and permeability performance of PTFE membrane,at the same time improve the waterproof and acoustic performance of PTFE membrane.