Original title: Brief Introduction of medical protective suit and Detection
Technology Under the current situation that COVID-19 is still raging, medical
protective suit is a necessary protective clothing to ensure the safety of
medical staff, public health workers, patients, hospital visitors and other
personnel entering the infected area, and its role also includes isolation of
pathogens, harmful ultra-fine dust, acid and alkaline solutions, etc., to ensure
the safety of life and work of relevant personnel, while keeping the environment
clean. 1. Disposable medical protective suit. The performance indicators of
medical protective suit mainly refer to protection, comfort, physical and
mechanical property, etc. Among them, the most important performance requirement
of medical protective suit is protection, which mainly includes liquid barrier,
microbial barrier and particulate matter barrier; comfort mainly refers to air
permeability and moisture permeability. In order to enhance the protective
effect, protective suit fabrics are usually laminated or laminated, which are
thick and have poor air permeability and moisture permeability. Long-term wear
requires ventilation, moisture permeability, perspiration and heat discharge;
physical mechanical property mainly refers to the performance of medical
protective suit materials such as tear resistance, puncture resistance and wear
resistance, so as to avoid providing channels for the spread of bacteria and
viruses. 2. Air permeability of medical protective suit. Disposable medical
protective suit materials need to meet the requirements of "three refusals and
one resistance" (water, blood, alcohol and antistatic). The composite material
can be compounded by different materials, such as polyethylene/polypropylene
spunbonded nonwoven cloth compounded with a breathable microporous film or other
nonwoven cloth, or spunlaced nonwoven cloth compounded with a breathable
microporous film, or wood pulp compounded with spunlaced nonwoven cloth. In
addition, some membrane materials made of polytetrafluoroethylene can be used to
make high-end protective suit fabrics. Among these materials, breathable
microporous films are particularly important. The so-called breathable film is
made by uniformly mixing a functional inorganic product into the polyolefin raw
material, so that the product generates pores due to high stretching in the film
forming process, thereby having the functions of air permeability and moisture
conduction; the functions of the breathable film are briefly described as water
resistance and air permeability (moisture), taking the most commonly used PE
breathable film as an example. (1) Principle of ventilation The principle is
very simple: inorganic substance + stretching = micropores. In fact, the
operation is very particular. Only the micropores with appropriate size and
uniform distribution are effective, as shown in Figure 2: Figure 2. Effective
pore size of breathable film If the stretching is insufficient, the pore
diameter will be too small or even no pore diameter, while the poor stretching
and the micropores with insufficient size can only be used as waste products.
(2) Basic film-forming principle of breathable film Film-forming principle of
breathable film: PE + CaCO (masterbatch)-film-forming-stretching-breathable
film. PE breathable film is made by blending LDPE/LLDPE polyethylene resin
carrier with about 50% special calcium carbonate, extruding into film and
directionally stretching to a certain ratio. As that polyethylene resin is a
thermoplastic plastic material, the polyethylene resin can be stretch and
crystallized unde certain conditions, the interface between the polymer and the
calcium carbonate particles is peeled off dure stretching, winding pores or
channels which are communicated with each other are formed around the calcium
carbonate particles, and the pores and the channels endow the film with a
ventilation (moisture) function, so that the environments on both sides of the
film are communicated. (3) The action mechanism of gas permeable membrane A
humidity gradient pressure difference is formed when the water vapor
concentration on one side of the membrane is greater than the environment on the
other side of the membrane. This provides the basic condition for gas (vapor)
convection,
Medical
Disposable Coverall, and the humidity environment on both sides of the film
tends to be relatively balanced due to the formation of convection. The
breathable membrane is used as a water barrier membrane, which has a barrier
effect on liquid. Because there are many paths in the membrane, the
"length-diameter ratio" (L/D) value of the tortuous channel formed by the
membrane is very large, which can be understood as capillary. Therefore, in the
case of the same liquid (such as water) and the same pressure, as long as the
liquid column height of the capillary is less than the length of the capillary,
it can ensure that the liquid will not leak out. Expand the full text 3.
Classification of medical protective suit. At present, the materials used in
medical protective suit on the market are different, but no matter what kind of
materials are used, they should meet the requirements of various indicators.
Since SARS, various kinds of medical protective suit have emerged. However,
according to the form of use, it can be roughly divided into reusable type and
disposable type. (1) Reusable medical protective suit material Reusable types
include: traditional woven fabrics made of natural fibers (cotton, hemp) and
synthetic fibers (polyester, nylon) and their blends; high-density structural
fabrics made of superfine filaments; laminated fabrics made by laminating
microporous films and ordinary fabrics. Traditional woven fabric: a reusable
woven fabric made of natural fibers (cotton, hemp) and synthetic fibers
(polyester, nylon) and blends of the two. Traditional cotton surgical gown is
still widely used because of its good comfort, but cotton fabric is easy to
absorb pollutants and microorganisms in the air, and its good hygroscopicity
becomes a favorable condition for the survival of microorganisms. In addition,
cotton fabrics do not prevent the penetration of blood and other liquids.
High-density fabric: High-count cotton yarn or other superfine synthetic
filament is used to weave high-density fabric, so that the yarn gap becomes very
small. The fabric has moisture permeability due to the capillary action of
fibers,
Medical Disposable Coverall
,
Antivirus
Disposable Mask with CE Certificate, and has certain liquid penetration
resistance after being finished by fluorocarbon, silicone and other waterproof
agents, but there are still gaps on the surface of the fabric. Although this
kind of fabric has excellent moisture permeability, drapability and good handle,
its resistance to water pressure is poor. Coated fabric: The fabric is coated
directly or by the transfer method, so that the surface of the fabric is sealed
by the coating agent, thus having impermeability. The coating agent comprises
polyurethane, polyvinyl chloride, polyacrylate, organosilicon rubber and the
like. The moisture permeability of fabric is obtained by the action of
microporous structure or hydrophilic groups formed by special methods on the
coating. Coated fabrics can be divided into hydrophilic coated fabrics and
microporous coated fabrics. The hydrophilic coated fabric achieves the function
of moisture vapor permeability by forming pores allowing water vapor to pass
through through the free volume formed by the thermal movement of the coating
agent polymer and the space between the polymers. Due to the presence of
hydrophilic groups, sweat water vapor molecules pass through the coating through
the action of adsorption-diffusion-desorption. Microporous coated fabrics allow
water vapor to pass through by forming a permanent microporous and channel
system of 2 to 3 μm in the coating agent. Generally speaking, coated fabrics are
easy to process, have high water pressure resistance and strong permeability
resistance, but have poor moisture permeability. Laminated fabrics: Laminated
fabrics are generally made by laminating ordinary fabrics with a special film.
For example, PTFE (polytetrafluoroethylene) super waterproof and
moisture-permeable composite fabrics are due to the micropores of the PTFE
membrane of the main body of the fabric. On the other hand, the porosity of the
film is high, the pore diameter is larger than the diameter of water vapor
molecules, the water vapor molecules can freely pass through, and the moisture
vapor permeability is good. (2) use disposable medical protective suit material
The disposable type is generally a nonwoven material. Spunlaced nonwovens,
spunbonded nonwovens, flash evaporation nonwovens and SMS composites are the
main types of medical protective suit. Spunbonded method: Spunbonded method is
also called spunlaid method. The principle of spunlaid and the properties of
fiber web are very similar to those of silkworm silk screen, except that it uses
resin as raw material, uses chemical fiber spinning method to form filament, and
then uses airflow or mechanical method to separate filament into web, and in
most cases, it needs to achieve the purpose of cloth formation through
consolidation process. Nonwovens produced by this process are very close to
traditional textiles in terms of hand feeling and performance, and polypropylene
spunbonded fabrics are more mature in domestic technology. Flash process: Flash
process is also known as instantaneous solvent evaporation spunlaid process,
which uses polyethylene hydrocarbon as the main raw material. Different from the
spunbonding method which uses airflow to separate filaments or the combination
of airflow and machinery to separate filaments, the flash evaporation method
uses electrostatic separation, that is, the electrostatic generator or
electrostatic salt additive is used to form an electrostatic field, so that the
filaments rub against each other in the stretching process to form electrostatic
separation filaments, which repel each other and maintain a single fiber state,
and then the fibers are condensed into a web by an electrostatic device, and the
web is then hot-rolled to form the flash evaporation nonwoven fabric. The
"Tyvek" series of nonwovens developed by Dupont is manufactured by flash
evaporation. Spunlaced process: Spunlaced nonwovens production process is a new
type of nonwovens processing technology, which was successfully developed by
Dupont and Chicopee companies in the United States in the mid-1970s. Spunlace
process, also known as jet spraying process, is to spray the fiber web through
high-pressure water column and high-speed water flow, so that the fibers in the
fiber web move, rearrange and entangle with each other under the action of water
power, so as to achieve the purpose of consolidation into cloth. Spunlaced
nonwovens have the advantages of high strength, good moisture absorption and air
permeability, not easy to fluff, soft handle, good drapability and no chemical
adhesives. The main raw materials are polyester, nylon, polypropylene, viscose,
absorbent cotton fiber or pulp and other functional fibers. SMS composite
nonwovens: Composite nonwovens are nonwovens made by combining two or more
nonwoven webs with different properties (or nonwoven fabrics with other textiles
and plastics) by chemical, thermal or mechanical means, or by combining
different web forming processes. The composite products with nonwovens as the
main body processed by these methods integrate the excellent properties of
various materials, and the comprehensive properties of the products are fully
enhanced through the complementary properties of various composite materials. 4.
Relevant standards for medical protective suit. In terms of packaging and
labeling of protective footwear products, China's standards, NFPA 1999 of the
United States and EU standards have made more comprehensive and strict
provisions. China's GB 19082-2009 "Technical Requirements for Disposable Medical
protective suit" stipulates that the protective suit is composed of hooded
jacket and trousers, which is divided into one-piece structure and split-body
structure, and is not suitable for reusable protective suit, and stipulates the
flame retardant performance, water level, charge density, elongation at break
and waterproof indicators of medical protective suit. The protective suit
applicable to NFPA 1999 standard in the United States are divided into
disposable and reusable ones, including split and one-piece work clothes and
patient-used ones. In addition to the conventional physical strength
performance, flame retardant performance and other indicators, the standard also
requires overall testing, and the isolation layer and joints should be tested
for liquid resistance and microbial penetration. The European Union's EN
14126-2003 "Anti-infective protective suit for protective suit-Performance
requirements and test methods" is applicable to repeatable and limited-use
protective suit, but it is not suitable for surgeons and patients to avoid cross
infection during surgery. It is required that the joints of the protective suit
shall comply with the strength requirements in the EN 14325. The whole set of
protective suit is divided into 6 categories according to the protection
performance, from type 1 to type 6, the smaller the number is, the higher the
protection is; type 4 is the recommended medical requirement,
Medical Full Body Coverall, the type
with (B) is biological protection, and generally the protective suit with type B
is preferred. Above is about "the medical protective suit and the examination
technology brief introduction" the content introduction, hoped may bring some
help to you. Return to Sohu to see more Responsible Editor:.
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