As of 24:00 on February 2, a total of 17,205 cases of novel coronavirus pneumonia have been confirmed nationwide, with 361 deaths, 475 recoveries, and a total of 21,558 suspected cases. In order to prevent the epidemic from continuing to spread, medical masks have become a must-have item. For medical staff who are fighting on the front line to save lives and heal the wounded, medical protective equipment such as medical masks and medical disposable protective clothing are essential materials to ensure their safety. How much do you know about medical protective materials? Let’s learn about medical protective materials together.
Standards for medical protective materials
Since the outbreak of SARS in 2003, how to ensure the safety of medical personnel and avoid cross-infection in hospitals has become a focus. Countries have begun to formulate standards specifically for medical protective clothing, including: AAMI PB 70, a standard formulated by the Association for the Advancement of Medical Instrumentation (AAMI) in 2003 for evaluating the barrier properties of sanitary protective clothing. ; NFPA 1999, a standard formulated by NFPA for medical emergency protective clothing; EN 13795, a standard formulated by the European Committee for Standardization (ECS) in 2004; ISO 16542, a standard formulated by the ISO organization in 2004. In addition, Canada and other countries and international organizations have also issued relevant standards. Our country has also formulated technical requirements for medical disposable protective clothing GB 19082-2009, textiles-nonwovens standard for surgical protection GB/T 38014-2019, standards for medical protective masks GB 19083-2010, and standards for durable protective clothing. WSB58 (Standard of the Ministry of Health of the General Logistics Department of the Chinese People’s Liberation Army) for performance evaluation, etc.
Surgical gowns/drapes specified by AAMI PB 70 standard Waterproof barrier rating
Comparison and analysis of common mask implementation standards
Performance requirements for medical protective materials
The basic requirements for medical protective materials are to block microorganisms, block water, and be breathable , anti-static, etc. Clinical application prevents medical staff from being infected by germs carried by patients through contact during diagnosis, treatment and care; it is also necessary to prevent microorganisms carried by medical staff themselves from contaminating patients, especially during surgeries and other aseptic operations, to prevent contamination and cause to the role of two-way protection. At the same time, it is necessary to ensure the wearer’s comfort and safety performance requirements under normal use.
Therefore, the overall requirements for medical protective materials are:
(1) Can effectively block microorganisms, particulate matter and liquids;
(2) It has a certain degree of breathability and comfort, and after repeated washing and disinfection, it can maintain sufficient integrity and durability, and the barrier effect can still meet the specifications. Basic requirements;
(3) Have certain tear resistance and abrasion resistance, no flocculation and no dust production;
(4) High-protection materials must have certain resistance to chemical reagents;
(5) High reuse times and good performance-price ratio.
Polyester filament three Schematic diagram of the structure of layered composite medical protective materials and their protective effects
Schematic diagram of microporous breathable anti-virus fabric
Non-woven medical protective material
Since most pollution and hazards are spread through air or liquid, traditional textile protective materials are woven from yarns. The yarns are relatively thick, resulting in poor barrier properties of the products. Seriously affects its protective performance. Secondly, traditional medical protective materials are generally made of cotton fabrics after finishing. The processing technology is complex, the process and cycle are long, and the cost of using medical protective materials is high. Moreover, traditional textile protective materials are reused after high-temperature sterilization and disinfection, and the processing cost is relatively high; they need to be washed repeatedly during use, and the fluff that falls off the surface of the cotton fabric will become a carrier of bacterial particles, causing further infection of the wound. In addition, with the improvement of living standards, people will have a certain psychological resistance to such reusable products and have doubts about the effect of high-temperature sterilization and disinfection. Therefore, traditional textile protective materials are gradually being replaced by disposable non-woven protective materials. material replaced.
High-protection surgical gown produced by polyester filament 3-layer composite material processing
Preparation technology of nonwoven medical protective materials
1 Spunbond nonwoven technology
Spunbond nonwoven materials are prepared by direct melt spinning of polymer slice raw materials. No chemical adhesives and other substances are added during the production process. The selected polymer materials themselves are harmless to the human body. Therefore, it is increasingly used in the medical and health fields. Although spunbond nonwoven materials meet the requirements for strength and comfort as protective materials, their barrier properties are relatively weak. In response to this problem, countries around the world are learning from the ultrafine fiber technology of the melt-blown method and taking certain measures to make the spunbonded nonwoven fibers have a certain strength and ensure the formation of ultrafine fibers. Therefore, fine denier spunbond Technology has become a major research hotspot in spunbond technology.
What emerged was the two-component spunbond spunlace technology. The products produced by this technology are fiber-spreaded on the basis of ordinary round fibers. Currently, 16-petal and It has 32 spinnerets, so the fiber diameter after fiber opening is very thin, and the cross-section is wedge-shaped rather than circular. The appearance and softness of the product after spunlace fiber opening are very similar to textiles, and its barrier properties are relatively better than ordinary spun fibers. Sticky or spunlace nonwoven materials are good and therefore can be used as medical protective materials.
Bicomponent spunbond fiber cross-section and electron microscope surface image
2 Melt-blown nonwoven technology
The biggest feature of the melt-blown method is that the fibers are very thin, with a diameter of only a few Micron, after being self-adhesive, the structure is fluffy, the porosity is high, the average pore size is small, and it has very good barrier properties. Therefore, the barrier performance of medical protective materials is better than that of spunbond and spunlace nonwoven materials. However, since there is no long cooling drafting area during the preparation process, but is cooled at room temperature, the strength and wear resistance of the product are not high.
3 SMS composite technology
Between the above-mentioned spunbond nonwovens Due to the poor material barrier effect and low strength of melt-blown nonwoven materials, some people used the strength and wear resistance of spunbonded cloth as the surface layer, and used the barrier properties of melt-blown cloth as the core layer to prepare SMS composite non-woven materials. Woven materials. Considering the issues of production investment and cost, current SMS compounding technology can be divided into three categories: online compounding, offline compounding and one-and-a-half-step compounding. Among them, online lamination is a combination of spunbond and melt-blown production lines. It has the highest investment, but the prepared product has the best performance and can be made into very thin products. The proportion of melt-blown materials is adjustable, and the material’s breathability and moisture permeability and barrier properties are The performance is very good and it is an ideal medical protective material. Offline lamination is a two-step lamination of the prepared melt-blown fabric and spunbond fabric. The two separate products cannot be made too thin, and both need to go through a fixed mesh. After lamination, the product cannot be made too thin, although the barrier properties Very good, but has poor breathability and moisture permeability. It can be used in protective materials that do not have high requirements for breathability and moisture permeability but have high requirements for barrier properties. The one-and-a-half-step method improves the problem of poor breathability and moisture permeability of offline lamination, but the cost is lower than that of online lamination. The products produced have better performance and can be used in medical protective materials.
Online SMS principle and SMS product structure
4 Spunlace nonwoven technology
For nonwoven materials in which short fibers are carded into a web and then spunlace to fix the web, although It has great advantages in wearing properties such as softness against the skin, moisture absorption and breathability. However, due to poor barrier properties, it can only be used as general medical materials, and its protective performance is not very good.
Anti-cross-infection spunlace nonwoven material for door handles developed by the University of Leeds, UK
5 Flash nonwoven technology
Flash nonwovens are made of high molecular weight polyethylene (PE) is used as the raw material, and methylene chloride is used as the solvent. Under the protection of high pressure of carbon dioxide, it is ejected from the spinneret at high speed. After the solvent evaporates rapidly, the filaments solidify, and then are drawn to form ultra-fine fibers, which are laid on the fiber through electrostatic separation. A fiber mesh is formed on the mesh curtain, which is then hot-rolled and reinforced. Compared with SMS, flash evaporation technology uses a solution spinning method. The solvent is a volatile organic solvent, which is difficult to recycle. Its high concentration in the air can easily cause explosion accidents. In addition, during the production process, the spinning of the fiber Speed control is very difficult. This technology is currently monopolized by DuPont of the United States. The protective clothing made of its flash evaporation product Tyvek combines protection, durability and comfort, and can protect workers from injuries as small as micron-sized particles, but the cost is relatively high. higher.
The principle of flash steamed nonwovens
Flash-steamed nonwoven materials and protective clothing
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