Due to the limited expansion of covid-19 epidemic in the global scope, the demand for anti-epidemic masks is increasing all over the world. The economic benefits from the huge market demand have led to the emergence of a large number of substandard mask products in the market, among which the quality is the most important difference lies in the advantages and disadvantages of the mask lining fusing cloth.
Melt-blown is an important material for the production of surgical masks and N95 masks. It is called the “heart” of masks.
“There is no supply of melt-sprayed cloth, which is the core of masks,” said he, head of a clothing factory in quzhou, zhejiang province, according to Chinese media. A short month, a lot of enterprises are to produce masks, although the price of melt-blown cloth price increase is very big, but at present China melt-spraying cloth shortage is severe, there is no so much melt-spraying cloth supply market, now stuck in the melt-spraying cloth link.
What is melt-blown fabric?
Cut open an already used surgical mask and you’ll find: the mask has three layers:
- the inner S layer is ordinary non-woven fabric, which mainly functions as moisture absorption;
- the outer S layer is a non-woven cloth with waterproof treatment, which is mainly used to isolate the fluid from the patient and prevent droplets.
- the middle M layer is the most important core layer, which USES a melt spray cloth with electret treatment to filter bacterial suspended particles.
Melt spray cloth is a kind of polypropylene with high melt index as the material, by many criss-cross fiber with random direction laminated film, the fiber diameter range of 0.5~10 micron, its fiber diameter is about one thirtieth of the hair.
N95 level mask, optimized in structure :(middle level) more layers of core filter, thicker thickness. An ordinary surgical mask needs about 1g fusible spraying cloth +2g spunbonded cloth. An N95 mask, about 3-4g fusible spraying cloth +4g spunbonded cloth composition.
Although the size of novel coronavirus is very small, about 100 nm (0.1 micron), but the virus can not exist independently, its transmission route is mainly secretions and sneezing droplets, droplets in the size of about 5 micron, this is one;
Second, fusion-spraying cloth is essentially a fiber filter, containing virus droplets near the fusion-spraying cloth, will be electrostatic adsorption on the surface, can not pass through.
How did melt-spraying cloth come about?
The S layer and the M layer of the mask, although the raw material is polypropylene special resin, but melt spraying cloth special material and other non-woven fabric raw material, there are some differences in the production process, such as the M layer on a modified plastic link.
Special material for melt spraying cloth
Melt spraying cloth special material is high melt index polypropylene. Polypropylene melt index is higher, melt out of the fiber is finer, made of melt spray cloth filter is also better.
Oil → atmospheric decompression unit/secondary coking hydrocracking naphtha/hydrocracking light naphtha → ethylene cracking unit → ethylene/propylene → ethylene oxide/polypropylene (special resin)
S layer (spunbonded layer) : polypropylene resin → send to non-woven fabric factory to produce S layer → send to mask factory
M layer (fusible spray layer) : polypropylene resin → send to the modified plastic factory to produce fusible spray cloth material → send to the fusible spray nonwoven factory to make M layer → send to the mask factory
Because polypropylene, the raw material of melt-spraying cloth, is taken from petroleum, petrochemical enterprises have advantages in producing melt-spraying cloth.
Identify melted spray cloth
Many fake mask manufacturers took advantage of the loophole, in order to profit from the use of extremely poor quality, cheap, substandard raw materials, a turnover of nearly 10 times.
Some direct omit the most important melt spray cloth filter layer in the middle, with ordinary non-woven cloth instead, did not play the role of filtering virus, may also produce harm to the body!
So how do you tell if the laminated spray fabric in a surgical mask is real?
The two layers of inferior quality are easy to identify. A useful surgical mask must have three layers of spunbonded nonwoven fabric on each side and a full gram of melted spray cloth in the middle.
The figure shows the melting spray cloth. The filtering effect is related to its gram weight (grams per square meter). This range is 18-500g, 40-50g above the filtering effect is good.
Good fusion-sprayed cloth looks white instead of transparent due to its heavy weight in grams, and it looks distinctly different from the spunbonded non-woven fabric on both sides, which, to put it bluntly, looks like paper. If it looks different but obviously thin, it is a melted spray cloth with a small weight in grams. The thinner the melt spray cloth, the worse the effect.
Simple identification method:
First, as the name suggests, the spray layer melts when it encounters fire, not when it burns. Paper burns when it meets fire.
Second, melting spray layer has static electricity, you will melt spray layer into a strip, will obviously feel the electrostatic adsorption effect, can also be a strip of molten spray layer adsorption on stainless steel.
So at the end of the day you can take the mask off and look at it,
Avoid wearing a fake mask