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How to produce meltblown cloth

May 23, 2020

Meltblown fabric can be called the "heart" of medical surgical masks and N95 masks. Medical surgical masks and N95 masks generally adopt a multi-layer structure, referred to as SMS structure: a single layer of spunbond layer (S) on both sides; Spray layer (M) is generally divided into single layer or multiple layers. The plane masks are generally polypropylene PP spunbond + meltblown + PP spunbond, you can also use a layer of short fiber to improve the skin touch. Three-dimensional cup-shaped masks are generally PET polyester needle punched cotton + meltblown + needle punched cotton or PP spunbond. Among them, the outer layer is a non-woven fabric with waterproof treatment, which is mainly used to isolate the droplets sprayed by the patient; the middle melt-blown layer is a specially processed melt-blown non-woven fabric, which has good filtering and shielding properties , Heat insulation and oil absorption, is an important raw material for the production of masks; the inner layer is ordinary non-woven fabrics. Although the spunbond layer (S) and the meltblown layer (M) of the mask are non-woven fabrics, the raw materials are polypropylene, but the manufacturing process is not the same. Among them, the fiber diameter of the spunbond layer on both sides is thicker, about 20 microns; the fiber diameter of the middle meltblown layer is only 2 microns, made of a polypropylene material called high-melt fat fiber.

The specific production method is to feed polypropylene PP resin chips into a screw extruder, which is heated and melted and extruded from the nozzle. The polymer melted at the outlet of the die is stretched by a high-speed hot air flow, and cold air is drawn from both sides of the die It is supplemented to cool and solidify the fibers to form ultrafine short fibers. Under the action of the airflow, these short fibers are aggregated onto the fiber collection device to form a fiber web or core tube. The melt-blowing process is a one-step molding process from slicing thermoplastic resin to making fiber mesh belt (cloth / core tube), so the process flow is short, the product is formed in one step, and the production efficiency is high. By adjusting the combination of melt-blowing processes, product structure combinations of different fiber wire diameters (0.5-30 μm) and fiber mesh pore sizes can be achieved, thereby meeting the design requirements of various filtration functions. The melt-blown process is applicable to a wide range of raw materials and is suitable for processing various materials such as polypropylene, polyester, nylon, etc. Currently, polypropylene PP materials account for more than 95%. The web structure of melt-blown products is formed by its own thermal bonding and entanglement, without any chemical adhesives, additives, and pollution.

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