Preparation method of hollow fiber internal pressure composite film

Abstract

The invention discloses a preparation method of a hollow fiber internal pressure composite film, and aims to provide a preparation method of a hollow fiber internal pressure composite film with high supporting property and high pressure resistance. The preparation method comprises the following steps of: uniformly blending an outer layer film forming material, an outer layer film forming diluent and an outer layer film forming additive in a fusing process to obtain a thermally induced phase separation method outer layer film forming system; dissolving and uniformly mixing an inner layer film forming material, an inner layer film forming solvent and an inner layer film pore forming agent to obtain a non-solvent induced phase separation method inner layer film forming system, wherein the inner layer film pore forming agent contains over 70 percent of water-soluble polymer; and extruding and spinning in a composite way by introducing a core liquid into a central pipe, taking the inner layer film forming system as a middle layer and taking the outer layer film forming system as the outside, quickly soaking into a coagulation bath, fully curing an outer layer and an inner layer under the actions of the coagulation bath and the core liquid, and extracting and washing to obtain the hollow fiber internal pressure composite film. The large-inner-diameter hollow fiber internal pressure composite film prepared with the method disclosed by the invention can be used for replacing a tubular film during application.

Description

technical field [0001] The invention belongs to the technical field of hollow fiber membrane preparation, and more specifically relates to a method for preparing a hollow fiber internal pressure composite membrane. Background technique [0002] Hollow fiber membrane, as a high-efficiency separation material, has been widely used in various fields such as water treatment. According to the requirements of use, the hollow fiber membrane with the outer surface as the separation function layer is usually called the hollow fiber outer pressure membrane, and the hollow fiber membrane with the inner surface as the separation function layer is called the hollow fiber inner pressure membrane. For the hollow fiber internal pressure membrane, in order to ensure the smooth flow of the liquid in the hollow fiber tube, it is necessary to maintain a high support of the membrane; The inner diameter, pressure resistance and water hammer impact resistance of the fiber inner pressure membrane;...

AI Technical Summary

Problems solved by technology

[0003] The existing hollow fiber internal pressure membrane is mainly a single-layer membrane prepared by the non-solvent-induced phase separation (NIPS) method. The hollow fiber internal pressure membrane obtained by this method has a dense layer of small pores on the inner surface, and the separation accuracy is high. The disadvantage is that the mechanical properties are low. In the actual application process, the membrane filaments are easily damaged due to poor mechanical properties, resulting in a decrease in its service life.

In addition, due to the limitations of the preparation method, in order to meet the requirements of the hollow fiber internal pressure membrane for pressure resistance and support performance, the selection of membrane materials is also subject to greater restrictions. For example, the hollow fiber internal pressure membrane with excellent comprehensive performance is currently on the market. Membrane products mainly focus on hollow fiber internal pressure membranes of polymer materials such as polysulfone (PS), polyethersulfone (PES) and sulfonated polyethersulfone (SPES). The reason is that polymer materials such as PS, PES and SPES themselves The modulus after forming is relatively high, but the wall thickness of the obtained hollow fiber internal pressure membrane must be ensured, resulting in the waste of such relatively high-cost membrane materials