Automatic Stopping Mechanism And Structure Designing Of The Melt-blown Porous Materials

Along with the social progress and the development of the medical treatment, therequirements for security and humanity of medical is on the increasing, the automatic stoppinginfusion arises under this kind of background. The current automatic stopping infusion can bedivided into two types according to the design concept, respectively,buoy structure andmembrane structure. The automatic stopping infusion of membrane structure are introduced fromabroad, The automatic stopping membrane is a porous microfiltration membrane, It combines theautomatic stopping capability with filtering capability, Although it has more marketcompetitiveness, but too expensive. And melt-blown material is a kind of porous material withhigh filtration function. The project aims at knowing the automatic stopping mechanism, anddesign the structure of melt-blown material according to the automatic stopping mechanism, itmay achieve the request for utilization and instead of the automatic stopping mechanism, reduceproduction cost and enhance competitive power of products, at the same time reduce the burden ofpatients.The paper divides into four parts. Firstly, the performance of the imported PES membranewere tested, including its surface morphology, pore size and pore size distribution, thickness andthe contact angle, simulating the effect of infusion and so on. The result is that the PES membranehas good performance, and infer that the biggest factor that influence the automatic stopping effectshould be the size of the aperture.Then, in order to study the influencing factors of the automatic stopping, research theautomatic stopping mechanism and balance equation were derived. The principle analyse ofautomatic stopping as follow. the automatic stopping infusion, liquid level stop dropping, theliquid in the eyedropper bear four pressures, respectively, upward venous pressure P1and bubblepressure P2of the automatic stopping material, downward liquid hydrostatic pressure P3andatmospheric pressure P4. The condition that the automatic stopping material can work is: P1+P2≥P3+P4. Theoretical analysis discloses the relation between bubble pressure of the automaticstopping material and the stopping height. Through the principle analysis of automatic stopping, the pore size of the automatic stopping material is the main factor that affects the automaticstopping effect. The smaller the aperture is, the bigger the bubble pressure is, the higher thestopping height is. The smaller the aperture is, the size of the particle can be intercepted is smaller,the higher the filtration efficiency is.Then, the performance of PP melt-blown automatic stopping material were tested, andthrough hot-press treatment on PBT material to decrease the diameter to give it the automaticstopping effect. The properties of the PBT material before and after hot-press treatment weretested. Related performance tests including electron microscopy (sem), fiber diameter, surfacedensity, thickness, contact angle, aperture size and distribution, crease recovery angle, etc.Through comparison and analysis, after hot-press treatment of PBT melt-blown material in thepore size and crease recovery angle is better than PP melt-blown material. That means itsautomatic stopping effect and crease recovery is better. But the thickness and surface density ofPBT melt-blown material is bigger than the PP material, and the contact angle is bigger than thePP material.Finally, simulated infusion experiment is designed. Namely make PBT material intoautomatic stopping device and install it in different positions of the infusion to watch if it canautomatic stopping, meanwhile, measure its velocity. Then through the balance formula in frontto calculate the theoretical stopping height, by comparing with actual values to determine if thebalance formula are true. The analysis results are as follows. The automatic stopping device makeof untreated PBT material can not stop liquid both in height of40cm and150cm, while, Theautomatic stopping device make of110℃hot-press treatment PBT material can stop liquid both inheight of40cm and150cm. Even squash the dropper with hand, it still can stop the liquid, but itneeds more time to flow over the liquid under the same conditions.