Nowadays, masks are an essential item, and the most important component - melt-blown fabric - is the most crucial, with melt-blown fabric machines meeting a large demand for this component. In the following, we will describe what melt-blown fabrics are.

What is the melt-blown fabric?

melt-blown fabric is the core material of a mask. melt-blown fabric is mainly made of polypropylene, a membrane of many interlaced fibers laminated in a random direction. The higher the melt index of polypropylene, the finer the melt-blown fibers, and the better the filtering properties of the melt-blown fabric. The fibers can reach a diameter of 0.5-1.0μm, which is about one-thirtieth of a hair. With more voids, a fluffy structure and good wrinkle resistance, the microfibre with its unique capillary structure increases the number of fibers per unit area and surface area, resulting in good filtering, shielding, adiabatic, and oil absorption properties.

The main structure of the medical mask is a three-layer non-woven, i.e. SMS structure.  

The inner S-layer is a normal non-woven fabric, mainly for moisture absorption.

The outer S layer is a non-woven fabric with a waterproofing treatment, mainly used to insulate the patient's sprayed liquid and to provide an anti-droplet effect.

The middle M layer is made of electret-treated melt-blown nonwoven, which filters suspended particles of bacteria and is the most important core layer.   

1) Differences between S and M layers.

In the S and M layers of the masks, although the raw materials are polypropylene special resin, melt-blown cloth special material, and other non-woven raw materials, there are some differences in the production process, such as the M layer have an extra link of modified plastic.

Oil → normal pressure reduction unit / secondary coking and hydrogenated naphtha / hydrocracked light naphtha → ethylene cracking unit → ethylene/propylene → ethylene oxide/polypropylene (special resin)

S layer (spun bond layer): polypropylene special resin → sent to the non-woven plant to produce S layer → sent to mouthpiece plant

M layer (melt-blown layer): special resin for polypropylene → sent to modified plastics plant to produce special material for melt-blown fabric → sent to melt-blown nonwoven plant to make M layer → sent to mask plant

2) Electret treatment

In order to make breathing as smooth as possible while still meeting the protection requirements, qualified melt-blown fabrics for masks are subjected to an electropolishing process. The electret fibers have a large electrical charge on their surface, which intercepts fine particles through electrostatic adsorption. The classical physical characteristic of electrostatic adsorption can also be used to verify that the melt-blown fabric is electrically charged. The electret non-woven fabric is significantly attracted to hair, iron filings, etc. Although the small amount of melt-blown fabric in an individual mask may be less effective in attracting hair, the presence of an electrical charge can also allow it to be attracted to walls. Despite the presence of melt-blown fabric in some of the shoddy masks, it has not been electret, or the charge has been dissipated in large quantities because the electret technology is not up to scratch, or it has been stored for too long, and its protective properties are naturally not up to standard.　

Main specifications of melt-blown fabrics

Grammage: 18g-500g

Width: typically 160cm and 180cm (also available on request)

melt-blown fabrics are produced by drawing a fine stream of polymer melt from the spout holes of the die using a high-speed hot air stream, which forms ultra-fine fibers that are collected on a curtain or drum and bonded to themselves to form a melt-blown non-woven fabric.

The production process for melt-blown fabrics are mainly: melt preparation, filtration, metering, extrusion of the melt from the spinneret hole, drafting and cooling of the melt stream, and formation of the mesh.

So it is possible to identify genuine and fake melt-blown masks according to their grammage. A good melt-blown fabric looks white rather than transparent because it has enough grammage and looks distinctly different from the spun-bond non-woven on both sides. To put it bluntly, it looks like paper. If it looks different but is noticeably thinner, then it is a melt-blown fabric with a low weight. The thinner the melt-blown fabric, the worse the result.　

Simple identification methods.

1. The melt-blown layer will melt when exposed to fire, but will not burn. Paper will burn when it meets fire.

2. melt-blown layer has static electricity, you will melt-blown layer torn into a strip, and will obviously feel the electrostatic adsorption effect, but also a strip of melt-blown layer adsorbed on the stainless steel.

Application range of melt-blown fabric

(1) Medical and hygienic fabrics: surgical gowns, protective clothing, disinfection wraps, masks, diapers, women's sanitary napkins, etc.

(2) Home decoration fabrics: wall coverings, tablecloths, bed sheets, bedspreads, etc.

(3) Apparel fabrics: lining, bonded lining, wadding, shaped cotton, various synthetic leather backing fabrics, etc.

(4) Industrial fabrics: filter materials, insulation materials, cement packaging bags, geotextiles, coverings, etc.

(5) Agricultural fabrics: crop protection fabrics, rice planting fabrics, irrigation fabrics, insulation curtains, etc.

(6) Others: space cotton, heat, and sound insulation materials, oil-absorbing felt, cigarette filters, bagged tea bags, etc.