Microporous filter sheet prepared by interface macropore inhibition method

Abstract

For overcoming the defects of large pore diameter, non-uniform pore diameter distribution, low filtering precision and low filtering efficiency of a non-woven fabric manufactured by a traditional spunbond method, the advantages of high production efficiency and low cost are exerted. The microporous filter sheet is prepared by adopting an interface macropore inhibition method, so that the novel low-resistance, high-flux and economical filter material with proper micropores, high filter precision, high filter efficiency and proper air permeability is obtained. The microporous filter sheet is ofa layered composite material structure and has melting point with double peaks, a low-melting-point hot melt adhesive membrane is clamped between the high-melting-point spunbonded non-woven fabrics; the low-melting-point hot melt adhesive membrane molten fluid of a middle layer dispersedly flows into micropores of the non-woven fabric near the interface through hot air blowing in the thickness direction, and the purposes that the macropore diameter of the non-woven fabric near the interface is reduced, the local porosity is reduced, the air permeability is still kept, and the filtering efficiency is improved are achieved.

Description

technical field [0001] The invention belongs to the field of air filter materials for mask protection, and can also be used in air filter fields such as protective clothing, outdoor clothing, and air-conditioning filter materials with high requirements for ventilation, waterproof, and barrier. Background technique [0002] With the improvement of air pollution and air protection requirements for medical use, the filtration efficiency, filtration precision, filtration resistance and cost of air filter materials such as masks have received unprecedented attention. [0003] The current mainstream high-efficiency air filter materials mainly include: electret-treated melt-blown PP nonwovens, nanofiber microporous membranes produced by electrospinning, and PE or PTFE microporous membranes produced by bidirectional thermal stretching, the latter two Microporous membrane materials have high pore size precision and corresponding high filtration precision, but the manufacturing energy...

AI Technical Summary

Problems solved by technology

[0003] The current mainstream high-efficiency air filter materials mainly include: electret-treated melt-blown PP nonwovens, nanofiber microporous membranes produced by electrospinning, and PE or PTFE microporous membranes produced by bidirectional thermal stretching, the latter two Microporous membrane materials have high pore size precision and corresponding high filtration precision, but the manufacturing energy consumption of materials is high, the production line is complex and precise, and the cost is high; currently, mask protection, medical protective clothing, etc. are mainly used in melt-blown PP nonwovens. As the core air filter material, the mainstream application in the market is a one-step or two-step nonwoven material composite structure using SMS (spunbond / meltblown / spunbond) or SMMS (spunbond / two-layer meltblown / spunbond) , wherein the diameter of PP fibers in the middle melt-blown layer is generally between 2-8 microns, the arrangement is disorderly, the formed three-dimensional porous material has relatively small pore size and uniform pore size distribution, and the porosity is as high as 80-90%; and The PP fiber diameter of the spunbond layer on the surface is generally between 20-30 microns, its pore size is slightly larger than that of the melt-blown cloth, and the distribution of the pore size is not as fine as that of the melt-blown layer, although the porosity is similar to that of the melt-blown layer. It is close, but the filtration accuracy and filtration efficiency of the spunbond layer are far inferior to those produced by the meltblown method. Generally, the PP nonwoven material prepared by the spunbond method is used as a high-efficiency, low-cost dirt-holding layer, coarse filter layer, protection It is used in combination with the electret-treated melt-blown PP layer core filter material with high filtration accuracy; relatively speaking, the investment of a melt-blown production line is much greater than that of a spunbond line, and the difficulty of production control is also much greater than that of a spunbond In addition, the production efficiency of the melt-blown method is also low, resulting in a serious shortage of electret-treated melt-blown PP nonwovens, which is the core filter material for masks caused by the 2019 novel coronavirus epidemic.

[0004] In order to overcome the disadvantages of large pore size, uneven pore size distribution, low filtration precision and insufficient filtration efficiency of nonwoven fabrics produced by traditional spunbond method, and give full play to the advantages of high production efficiency and low cost; the present invention proposes a new creative technology According to the scheme, the microporous filter sheet is prepared by the interface macropore suppression method, and a low-resistance, high-throughput, economical new filter material with suitable small pores, high filtration precision, high filtration efficiency and suitable air permeability is obtained.

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