Preparation method of polypropylene millipore filtration sheet material

Abstract

The invention makes pubic a method to make polypropylene tiny hole filtering board. First, mix and churn up polypropylene powder and frothing agent for low boiling point liquid at a high speed so that the mixture temperature will goes up to 70~115 DEG C. Stop churning and cool the mixture. Pour chemical frothing agent, surface active agent, froth activator, and removing model agent, which all are milled and in paste state, into the mixture and then churn the mixture at a higher speed again. Put the mixture in the heated model cavity. Close the model and hot press it between the fixed model board and the movable model board of the pressing machine with force 0.5~10 MPa for 5~15 min. cool it until the temperature is same as room temperature. Remove the model and trim the edge, get the polypropylene tiny hole filtering board finally. Because the invention uses both chemical frothing agent and physic frothing agent and other assistant agent, it reduces working procedure, saves production period, cuts down the device investment and the cost. It can be used to make filtering unit for chemical purification, water purifying, air filter, exhausting auto wasted gas, mechanic appliance and battery.

Description

1. Technical field [0001] The invention belongs to the technical field of preparation of plastic microporous filter sheets, in particular to a method for pressing and preparing polypropylene microporous filter sheets. The microporous filter sheet produced by this preparation method can be used as filter sheet products in the fields of chemical purification, water purification treatment, air filtration, automobile exhaust emission, medical equipment and batteries. 2. Background technology [0002] Polypropylene (PP) is a general-purpose engineering plastic widely used. It has the characteristics of chemical corrosion resistance, non-toxic, odorless, good heat resistance (long-term use temperature of 120°C), excellent comprehensive mechanical properties and processability, and low cost. . In recent years, microporous filter sheets based on polypropylene have a tendency to replace polytetrafluoroethylene, ultra-high molecular weight polyethylene, polyvinyl chloride, and polyet...

AI Technical Summary

Problems solved by technology

[0010] Generally speaking, compared with the extrusion method, it is more economical to use the pressing method to produce polypropylene microporous filter sheets. However, the existing physical foaming-pressing method still has its unsatisfactory places: such as many processes , that is, the raw materials must be granulated, impregnated, washed, dried, pre-foamed, matured, and pressed to produce products, which has a long cycle and high production costs; secondly, because it is produced after pre-foaming and aging, Therefore, the obtained polypropylene microporous filter sheet is relatively soft, which cannot meet the requirement of bearing a certain pressure when used as a filter material, and because the pre-foamed particles are easily compacted during the compression molding process, the resulting micropores are easy to form Closed micropores are also difficult to meet the requirements for pore density, pore size and distribution, and gas permeability of polypropylene microporous filters during use.