Summary
Meltblown technology, as one of the polymer extrusion nonwovens, emerged as early as the 1950s. Later, through continuous technological progress and improvement, it has gradually formed a mature process.
GWELL entered the industry and formed GWELL’s own unique melt-blown fabric mask extrusion line. The main equipment configuration is feeder, screw extruder, metering pump, meltblown die combination, air compressor, air heater, receiving device, winding device. The process flow is: polymer preparation — melt extrusion — metering pump — meltblown die assembly — melt trickle stretching — cooling — receiving device.
The principle of melt-blown fabric mask extrusion line is to draw the polymer melt-extruded by the screw extruder, using high-speed hot air or other means to stretch the polymer melt-extruded by the die nozzle so that the microfiber is formed and condensed on the screen curtain or roller, and adheres to the nonwoven fabric by itself.
In being highly stretched, the polymer forms fabulous staple fibers. It condenses on the screen curtain to form a fiber net and is finally reinforced by self-bonding or thermal bonding to create a meltblown cloth.
Melt-blown fabric mask extrusion line mainly uses polypropylene as the primary raw material, and the fiber diameter can reach 1 to 5 microns. With many voids, fluffy structures, and good wrinkle resistance, these microfibers with unique capillary designs increase fibers’ number and surface area per unit area. The meltblown cloth has good filtration and shielding heat insulation and oil absorption.
It can be used in air, liquid filter materials, isolation materials, absorption materials, mask materials, thermal insulation materials, oil-absorbing materials, and wipes.
Production process of meltblown cloth for masks
GWELL as China melt-blown fabric mask extrusion line Supplier, The core of the whole mask is melt-blown nonwovens. Meltblown nonwovens are an ideal mask material. Due to the dense melt-blown layer, the thread density of the fibers is minimal. All of them are microfibers, which can reach 0.01~0.05dtex, about 1% of the thread density of ordinary spun-bond fibers.
The fibers of the melt-blown fabric mesh are fragile, and the fiber mesh is very uniform. When the liquid comes into contact, dust and bacteria are blocked because the surface tension liquid does not penetrate quickly. The gap formed by the connection between the microfibers is relatively tiny. The large specific surface area, combined with the irregular arrangement of nonwoven materials, etc. solves the contradiction between general filter media’s filtration effect and suction resistance.
1)Introduction to the process
Melting spinning includes many kinds, such as spunbond, meltblown, electrospinning, and its compounding methods. The melt-blown process is one of the melt-blown processes.
A high-speed hot airflow is used to draw a thin stream of polymer melt extruded from the die head spinneret, forming microfibers collected on the curtain or roller while self-bonding to develop melt-blown nonwovens.
The melt-blown process is characterized by the adoption of a single row of spray holes, the high-temperature polymer melt is ejected from the spray hole in the center of the spinneret, then drawn by the high-temperature airflow blown out from both sides at a certain angle, and finally relies on the waste heat of the fiber to form a meltblown cloth on the collection device.
2)Process flow
Meltblown: raw material conveying → screw melting → melt filtration → melt metering → spinning → hot air drawing → net laying → winding.
Anti-sticking: raw material conveying → screw melting → melt filtration → melt metering → spinning → hot air drawing → net laying → winding.
3)Process comparison
- Different requirements for raw materials
Spunbond PP resin MFI: 20~40g/10min
Meltblown PP resin MFI: 400~1200g/10min
- The stretching speed of the fiber is different
The stretching speed of meltblown fiber can reach more than 30km/min.
The fiber drawing speed of the spun-bond method can only reach up to 6000m/min.
- Different stretching distances
The stretching distance of the spun-bond method is 2~4m
The melt-blown method is only 10~30cm.
- Different cooling and stretching conditions
Cooling of spunbond silk strips: rely on air conditioning to cool the air; that is, the silk strips are cooled first to form newborn fibers
Meltblown filament cooling: by natural wind (actually air conditioning in the workshop).
- Different spinning temperatures
The short drawing distance of meltblown fiber requires better melt fluidity, so its spinning temperature is 50℃~80℃ higher than that of the spun-bond method.
SMS
The widely used nonwoven SMS mask combines two processes of spun bond and meltblown. It concentrates the high strength of spunbond nonwovens (S), minor vertical and horizontal strength differences, and the high shielding and waterproof properties of melt-blown nonwovens (M) into one material to form a mask with strong waterproof performance, good breathability and efficient isolation performance.
1) composite process
- One step method:
In a melt-blown fabric mask extrusion line, there are two spunbond spinning machines and a meltblown machine. The fibers ejected from them fall on the same curtain to form a three-layer fiber net; they are then followed by a hot rolling mill to create a composite nonwoven fabric that has only been bonded once.
- Two-step method:
In the anti-stick production line and meltblown production line, the spun bond cloth and meltblown cloth are produced in advance and compounded by lamination or other processes. After three sets of equipment in total, after obtaining S and M layers, a layer of meltblown cloth is sandwiched between the two layers of spun-bond fabric and hot-rolled and bonded to a three-layer composite SMS on a particular hot rolling laminating machine.
2)Electret process
- electret mechanism:
Corona charging is the most widely used method for producing electret filter materials in industrial production. Corona discharges that partially cause the breakdown of air using a uniform electric field to create ion beams that bombard the dielectric and cause ion charges to be deposited in the dielectric, and the material is charged.
- process:
The prepared melt-blown nonwoven fabric is placed on the electrode plate → multiple rows of corona needle tips are aligned with the specimen → open the high-voltage electrostatic generator needle tip voltage rises → reaches a specific voltage → the air near the electrode tip generates local corona discharge → electrons, or ions are released → the specimen surface below the electrode captures charges with the same polarity as the discharge needle → electrifies the polypropylene melt-blown fiber.
Because meltblown fiber of melt-blown fabric mask extrusion line is a kind of short fiber, fine fiber, but the fiber is vital, in addition to being the core material of medical protective products such as masks, it can also be used as environmental protection materials, such as oil absorbent materials, polypropylene melt-blown nonwovens become good oil absorption due to their material characteristics and microfiber structure Materials have been widely used in developed countries such as Europe, America, Japan and other developed countries, such as offshore oil spills, oil spills from factory equipment and sewage treatment. Therefore, the application field is vast and promising market prospects. Even after the epidemic is over, the market demand for meltblown cloth is enormous. Moreover, the epidemic is still spreading globally; masks still have a huge need, and customers hurry up the melt-blown fabric mask extrusion line is still a good choice.