At Present, Knowledge Of Medical Protective Materials Is Popular.

As of 24 February 4th, 24324 cases of new coronavirus pneumonia were identified, 490 cases died, 892 cases were cured, and there were 23260 suspected cases. In order to prevent the spread of the epidemic, medical masks are necessary for human hands. For medical personnel who are fighting for first-aid, medical masks, medical disposable protective clothing and other medical protective equipment are necessary materials to ensure their safety. How much do you know about medical protective materials? Let's take a look at the knowledge of medical protective materials.

Standard 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 the focus of attention. Every country has begun to formulate specific standards for medical protective clothing, including: the standard AAMI PB 70, which is applicable to the evaluation of barrier performance of protective clothing for health, developed by the Associationfor the Advancement of Medical Instrumentation (2003); the standard NFPA 1999 applied to medical emergency protective clothing developed by NFPA; the standard set by the European Standard Committee in 2004 (13795); the standard 16542 set by the 2004 organization in 2004. In addition, Canada and other countries and international organizations have issued relevant standards in succession. China has also formulated technical requirements for medical disposable protective clothing, GB 19082 - 2009, textiles - surgical protective nonwovens standard GB/T 38014 - 2019, standard GB 19083 - 2010 for medical masks, and WSB58 for performance evaluation of durable protective clothing (Ministry of health of the PLA General Logistics Department).

　　 AAMI / PB 70 standard for surgical clothing / surgery single waterproofing barrier

　　 Comparison and analysis of common mask execution standards

Performance requirements of medical protective materials

The basic requirements of medical protective materials are blocking microbes, water blocking, air permeability and antistatic. The clinical application prevents the medical staff from being infected by the pathogens carried by the patients in the course of diagnosis and treatment, and also prevents the microorganism contaminated by the medical staff themselves from polluting the patients, especially the operation and other aseptic operation processes, so as to prevent pollution and play a two-way protection role. At the same time, it is necessary to ensure the comfort and safety requirements of the wearer while satisfying the normal use.

Therefore, the general requirements for medical protective materials are:

(1) it can effectively block microbes, particulate matter and liquids.

(2) having a certain degree of permeability and comfort, and after repeated washing and disinfection, it can maintain enough integrity and durability, and the barrier effect can also meet the basic requirements of the specification.

(3) it has a certain degree of tear resistance and wear resistance, no flocculation and no dust production.

(4) high protective materials must possess certain resistance to chemical reagents.

(5) high reuse times and good performance price ratio.

　　 Schematic diagram and protective effect of three layer composite medical protective material for polyester filament

　　 Schematic diagram of breathless fabric without microporous ventilation

Nonwoven medical protective materials

Because most of the pollution and harm are transmitted by air or liquid, the traditional textile protective materials are made of yarns. Relatively speaking, the yarn is coarse, resulting in poor barrier performance and seriously affecting the protection performance. Secondly, the traditional medical protective materials are usually made of cotton fabric after finishing. The processing technology is complex, the process and the cycle are longer, and the cost of medical protective materials is higher. Moreover, the traditional textile protective materials are reused after high temperature sterilization and disinfection, and the treatment cost is relatively high. During the use process, repeated washing is needed, and the fuzz of the cotton fabric will become the carrier of bacterial particles, which will further infect the wound. In addition, with the improvement of living standards, people will feel a certain degree of psychological resistance to the repeated use of products. There is doubt about the effect of sterilization. Therefore, traditional textile protective materials are gradually replaced by disposable nonwoven protective materials.

　　 High protective surgical clothing produced by polyester filament 3 layer composite material

Preparation technology of nonwoven medical protective materials

1. Spunbonded nonwoven technology

Spunbonded nonwoven materials are made from direct melt spinning of polymer chips, and no chemical adhesives or other substances are added to the production process. The polymer materials selected are harmless to human body, so they are widely used in medical and health fields. Although spunbonded nonwoven material is used as protective material, its strength and comfort performance meet the requirements, but its barrier performance is relatively weak. To solve this problem, all countries in the world are drawing on the superfine fiber technology of melt blown method, and take certain measures to make spunbond nonwoven fibers both have certain strength and guarantee the formation of superfine fibers. Therefore, fine denier spunbonded technology has become a hot research topic of spunbonded technology.

The double component Spunlaced Spunlaced technology arises at the historic moment. The products produced by this technology are opened on the basis of ordinary round fibers. At present, 16 valve and 32 valve spinneret are commonly used. Therefore, after opening the fiber, the diameter of the fiber is very fine, and the cross section is not circular. The appearance and softness of the product are very similar to that of the textile, and its barrier property is better than that of ordinary spunbonded or spunlaced nonwoven materials, so it can be used for medical protection materials.

　　 Cross section and electron microscopy of two component spunbond fibers

2. Melt blown nonwoven technology

The biggest feature of melt blown method is that the fiber is very thin, only a few microns in diameter. After its adhesion, its structure is loose, its porosity is high, its average pore size is small, and it has very good barrier property. Therefore, the barrier performance of medical protective materials is better than that of spunbonded and spunlaced nonwoven materials. However, due to the fact that there is no longer cooling drafting area in the preparation process, instead of cooling at room temperature, the strength and wear resistance of the product are not high.

3, SMS composite technology

Because of the poor barrier effect of the spunbonded nonwoven materials and the low strength of melt blown nonwoven materials, some people have made use of the strength and wear resistance of spunbonded fabrics as the surface layer, and made use of the barrier properties of melt blown fabric as the core layer to prepare SMS composite nonwovens. Considering the issue of production investment and cost, SMS composite technology can be divided into three categories: Online composite, off-line composite and one-step and half way compound. The online compound is the combination of spunbonded and melt blown production line, with the highest investment, but the product is the best, and can be made into very thin products. The proportion of melt blown material can be adjusted, and its permeability, moisture permeability and barrier property are very good. It is an ideal medical protective material. The offline compound is to make the two parts of the prepared melt blown cloth and spunbonded cloth again, and the two separate products can not be made too thin, and all of them need to pass through the fixed network. After the combination, the products can not be made too thin. Although the barrier property is very good, the permeability and moisture permeability of the products are not good. One step and half method has improved the problem of poor performance of off-line composite ventilation and moisture permeability, but the cost is lower than that of on-line compound. The product has better performance and can be used for medical protective materials.

　　 Online SMS schematic and SMS product structure

4, spunlaced nonwoven technology

As for the nonwoven materials with short fibers, which are carded and netched and Spunlaced, have great advantages in softening, moisture absorption and breathability, but because of poor barrier performance, they can only be used as general medical materials, and their protective properties are not very good.

　　 Door handle, cross infection, spunlaced nonwovens developed by University of Leeds, UK

5. Flash Nonwovens Technology

Flash spinning nonwovens use high molecular weight polyethylene (PE) as raw material and dichloromethane as solvent. Under the high pressure protection of carbon dioxide, the spinneret is sped out at high speed, the solvent is rapidly evaporated and the wire is solidified, and then the superfine fiber is formed by drafting. The wire is laid on the net curtain through electrostatic separation, and then formed by hot rolling. Compared with SMS, flash technology is difficult to recover because of the solvent spinning method, solvent is volatile organic solvent, and high concentration in air is easy to cause explosion accidents. In addition, in the production process, the spinning speed control of fiber is very difficult. At present, the technology is monopolized by DuPont (DuPont) company, and its protective clothing made of Tyvek is combined with protection, durability and comfort. It can protect workers from small to micron size particles, but the cost is relatively high.

　　 Principle of flash Nonwovens

　　 Flash nonwovens and protective clothing