JimmieSears JimmieSears's blog : Brief Introduction of medical protective suit and Testing Technology _ Fabric
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,KN95
Mask with Fast Shipping, 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
,Medical
Disposable Coverall, 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,KN95 Face Mask, 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:. zjyuan-group.com
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