How much do you know about the "heart" meltblown of masks?
Recently, the outbreak of New Coronary Pneumonia has spread all over the world, and masks have become a shortage of supplies. Protective masks can not be processed without opening masks material, and the core of the mask fabric is the melt-blown cloth. Although the domestic production has been resumed, it is located in the production of masks. The upstream melt-blown cloth encountered supply disruption, which has become an important factor restricting the growth of mask production capacity in the short term.Mask is good or not, mainly depends on the quality of the melt-blown cloth, then what is the melt-blown cloth? What is it used for?
Definition and use of meltblown cloth
Meltblown cloth is the core material of the mask. Meltblown cloth mainly uses polypropylene as the main raw material, and the fiber diameter can reach 1 to 5 Micron. Multiple voids, fluffy structure, good fold resistance, ultra-fine fibers with unique capillary structure, can increase the single the number and surface area of the fiber in the bit area, so that the melt-blown cloth has good filtering, shielding, heat insulation and oil absorption Sex. Can be used for air, liquid filtration materials, insulation materials, absorption materials, mask materials, thermal insulation materials,oil absorption materials and wipers. Has many uses:
(1)Cloths for medical and health care: surgical clothing, protective clothing, disinfection cloths, masks, diapers, etc .;
(2)Fabrics for home decoration: wall coverings, tablecloths, bed sheets, bed covers, etc .;
(3)Cloths for clothing: lining, adhesive lining, flakes, shaped cotton, various synthetic leather bottom fabrics, etc .;
(4)Industrial fabrics: filter materials, insulating materials, cement bags, geotextiles, cladding cloths,etc.;
(5) Agricultural fabrics: crop protection fabrics, seedling raising fabrics, irrigation fabrics, thermal insulation curtains, etc .;
(6) Others: space cotton, thermal insulation and sound insulation materials, linoleum, cigarette filter, tea bags, etc.
How do masks stop viruses? How are meltblown fabrics produced?
Mainly rely on the mechanical barrier and electrostatic adsorption of the melt-blown cloth in the mask.
The protective effect of meltblown cloth
The masks currently used for virus protection are basically non-woven fabrics.Composed of woven fabric and melt-blown non-woven fabric. Medical masks are generally made of three layers of non-woven fabrics, as shown in Figure 1. material.
The material is spunbond nonwoven fabric + meltblown nonwoven fabric + spunbond nonwoven fabric, as shown as above, which is SMS(2Layer S layer and 1 layer M layer) structure, the spunbond non-woven fabric (S) has high strength, and the longitudinal and transverse strengths are different Small performance and high-shielding and water-proof performance of melt-blown non-woven fabric (M) are concentrated on one material, forming A mask with strong water-proof performance, good air permeability and high isolation performance.
The "S" and "M" layer materials are:
S is the spunbond layer (Spunbond), the fiber diameter is relatively thick, about 20 microns (μm), the outer layer S has dust resistance
Water blocking function, which can prevent the droplets from entering into the inside of the mask. The inner layer S has a water absorbing function, which can absorb and wear.
The moisture of the nose and mouth, the 2 layers of S spunbond layer support the whole non-woven fabric structure. SMS structure blocks the filtering effect
The results are shown as below.
The middle meltblown layer M (Meltblown) is the most important barrier layer, which is a very fine and electrostatic meltblown
nonwoven cloth, fiber diameter is about 2 microns (μm), dust, droplets containing bacteria, viruses are close to this meltblown nonwoven fabric
After that, it will be attracted to the surface of the meltblown cloth by static electricity and cannot penetrate. Suspended particles such as dust are captured by ultra-fine electrostatic fibers.
After living, it is very difficult to detach due to cleaning, and water washing will destroy the electrostatic suction ability, so this mask can only be used once use.
Production process of melt-blown cloth
01 Production process of meltblown cloth
The melt-blown fabric does not look special, but the production process is very complicated, and its production process can be summarized into three major links:
First, naphtha is extracted from petroleum, then chemically processed into polypropylene, and finally made into a cloth by melt-blowing process, roughly.
02 Production process of melt-blown cloth
The production process of meltblown cloth is mainly divided into three steps: melt extrusion, meltblown process and electret treatment.
As shown. Here we focus on the electoral treatment.
Electret refers to a dielectric material with long-term storage charge function, with high efficiency and low flow resistance,
The advantages of antibacterial and energy saving are added on the basis of ensuring the physical collision resistance of the conventional filter material.
Static electricity is attached to the role. The electret treatment makes the filter material fiber with charge, combined with melt-blown ultrafine fiber.
The characteristic of dense material, so a large number of electrodes are formed between the charged fiber dimensions, and the
charged fiber dimension can not only be enough.It attracts most of the charged particles in the environment like a magnet, and at the same time it can also dissipate some of the uncharged particles Polarization, and then attract some contaminants with smaller particle diameters, even nanometer-grade substances such as viruses Perform static electricity adsorption or charge repulsion blocking.The meltblown cloth used in medical masks must be electret treated. Sterile medical masks are sterilized by using ethylene oxide to kill bacteria
After that, there will be residual ethylene oxide on the mask, which not only stimulates the respiratory tract, but also causes
carcinogens. Must pass the method of analysis is to release the residual ethylene oxide to reach the safety content standard, and the whole
solution is detoxified. The standard process takes 7 days to half a month.
What kind of meltblown fabric is qualified?
Generally, you should send samples to a qualified laboratory for testing, and judge whether they are qualified according to the test results.
● Testing basis of meltblown cloth
1. Based on standards
FZ / T 64034-2014 Spunbond / meltblown / spunbond (SMS) method nonwoven
（1）Appearance quality inspection: fabric appearance, holes, impurities, odor, micropores, crystal points, frit, stiff wire, unreinforced area,
Thin mesh, width deviation, color difference, joint quality.
（2）Intrinsic quality detection: mass deviation rate per unit area, longitudinal breaking strength, transverse breaking strength, longitudinal and longitudinal breaking elongation Rate, hydrostatic pressure, breathability.
（3）Detection of microbiological indicators: total bacterial colonies, total fungal colonies, coliforms, and pathogenic pyogenic bacteria announcements.
Reprinted in: [Import and Export Manager]