Research On The Manufacture Of Nylon Superfine Fiber/polyurethane Composite Membrane And Its Properties

Nonwoven composite materials have been widely used as the filter material, which resulted from their advantages of low cost, high filtration and yield. A single species of film now cannot be fully meet the requirements of practical applications for the extension of needs to these film materials. Therefore, many researchers are paying attentions to changing structure of the materials for improving properties of films. As a kind of high performance material, superfine fiber composite materials have been widely used in our daily lives, e.g. suede and synthetic leather products fabricated by superfine fiber, and so on. In most recent years, polyamide superfine fibers have drawn many researchers attention in the area of the filter material because of its excellent heat resistance, weather resistance and excellent mechanical properties.In this paper, we investigated the splitting process of PA6 microfiber. PA6 microfibers were treated by impregnation and toluene extraction method. Splitting degree of PA6 microfibers were characterized by SEM, DSC, and weight loss rate at different process conditions. The process investigation indicated that Xylene was a valid additives for opening PA6/PE island composite microfiber. It can be prepared PA6 super fine fiber under the appropriate process conditions. Furthermore, the splitting degree of PA6/PE island type composite microfiber was mainly influenced by dissolution temperature and time. PE molecular chain movement is limited at lower temperatures. Therefore, it is difficult to move into Xylene for the PE, which resulted in insufficient extraction. Splitting rate was increased with the increasing of temperature and time, and reached equilibrium finally. The optimum technical parameters of splitting were finally obtained at 80 °C and 70 min. The splitting rate of fiber is controlled by analyzing the relationship between the condition and weight loss, and combined with DSC analysis, scanning electron microscopy.We also studied the effect of fibrillation process on PA6/PE microfiber substrate surface morphology, moisture permeability, infiltration, water absorption and mechanical properties which based on the study of fiber-opening process on PA6 microfiber. The results indicated that water vapor permeability of PU/PA6 microfiber increased with the increase of weight loss rate within a certain range. Some part of fiber fibrillated into ultra-fine fibers, which of this decreased the gap and increased dense between fibers, when the mass loss rate reached 20%. Thus, the journey of water vapor pass through fibers becomed longer and the total amount of water vapor permeability decreased which caused contact angle of composite fiber increased with the increasing of mass loss rate increases, i.e. wettability decreased with the increase of weight loss rate. Water absorption is increased with the increase of the weight loss rate in a certain range. However, the water absorption essentially unchanged with further increase the weight loss rate to 20%. The transverse and longitudinal strength of microfiber showed downward trend in the rate of weight loss with polyethylene dissolve, and finally leveling off.The microfiber flakes were composited with polyurethane emulsion by coating method which enables the polyurethane emulsion dipped inside of the fiber, and forms anchor with fiber by embedding in mutual. Thus, the hydrophilic PA6/PE microfiber nonwoven fabric as a base material for PU/PA6 multi-layer type filter material that with highly mechanical properties was obtained. The ideal method for wet coating deposition could be obtained by comparing and analyzing the wettability, water conductivity, water flux and mechanical properties of films.In this experiment, the fibrillation of PA6 microfiber technology and the composite method of polyurethane porous membrane fibers with nonwovens PA6 microfiber was systematic investigated. The corresponding performance was tested, the relationship between structure and performance were clarified. Based on these tests, a method for preparing PA6 microfiber nonwoven fabric, which used as a basic material PU /PA6 Multilayer filter material, was obtained. It provided theoretical basis and technical support for the excellent preparation of the key performance fine filter material. Additionally, it was explored new ideas and new methods for developing newly composite materials fine filtration.