Non-woven fabric processing technology-spinning into a net

Among the various process technologies of nonwovens, spunbond is a new and promising new technology. It was industrialized in the late 1960s by Dupont Company in the United States and Freudenberg  in Germany. In the late 1970s, different spunbond The production process was developed and industrialized by the United States, Germany, Britain, France, Italy and Japan. Compared with the dry process, it has the advantages of high output, short process flow, excellent product performance, and wide range of uses. The spunbond method eliminates the need for multiple processes such as fiber cutting, packaging, unpacking, mixing, carding, etc. Instead, it uses synthetic polymers as raw materials to form a web directly after spinning, and can use various methods to reinforce the web. , Making spunbonded nonwovens enter the application field of traditional textiles, and their application boundaries have been broken. From a technical point of view, the production efficiency and production capacity of spunbond equipment mainly depend on the drafting efficiency, spinning speed, the number of spinning boxes, the width of the template (number configuration), the web width and the web uniformity and Speed, fiber mesh and reinforcement technology, etc., on these key technical issues, various degrees of improvement and breakthroughs have been made in recent years. It creates conditions for the high efficiency of spunbond production equipment and products, reduces energy consumption, and reduces costs, so that spunbond nonwovens have a stronger competitive advantage. From the perspective of the output of spunbonded nonwovens, the global output of spunbonded nonwovens in the early 1980s was only 150,000 tons/year, and its output was nearly 600,000 tons/year in the early 1990s. Up to now, the global output of spunbonded nonwovens at the end of the 20th century has reached about 1 million tons per year, accounting for more than 35% of the total nonwovens output, and it is still growing at a rate of 8%. For example, the output of spunbonded nonwovens in countries and regions such as the United States and Western Europe accounted for more than 50% of the total output of nonwovens.


The basic principle is that, fundamentally speaking, the spinning method is an extension of chemical fiber spinning technology. It is after the polymer has been extruded and stretched to form continuous filaments, and then try to lay these continuous filaments into a net, and then through self-bonding, thermal bonding, chemical bonding or mechanical reinforcement methods, make The web becomes a non-woven fabric.


The spun-laid nonwoven fabric can basically use all polymers spun by chemical fibers as raw materials, but considering the spinning process performance, production cost and product use, the polymer actually used is thermoplastic The vast majority, such as polypropylene, polyester, polyethylene, polyamide, etc., use viscose in a very few cases. According to different polymers, the spun-laid nonwovens basically use melt spinning, and some use wet spinning or solvent spinning processes and other special processes.


After the polymer chips are added to the hopper, they are fed into the heated extruder. The polymer chips become a melt and are extruded by the screw of the extruder. The filtered melt is discharged from the spinneret of the spinning device by a metering pump. Many small holes are extruded to form a lot of filaments, which enter the quenching chamber. The cold air enters the quenching chamber from both sides, so that the hot melt filaments are cooled into filaments, and then enter the air gun or air tank, and pass through the high-speed air. It is stretched by the flow, placed on the netted curtain belt with suction below, and then transported to the reinforcement device, which is reinforced by any one or two methods of hot rolling, chemical bonding, needle punching, spunlacing, etc. It becomes a spun into a net nonwoven fabric.


In order to realize the production of polypropylene and polyester spunbond products on the same production line and the production of polypropylene superfine fibers (0.7 denier) spunbond products, Kobe Steel has improved the spunbond technology, especially in In terms of productivity. Kobe Steel has installed several unique sets of equipment in the spunbond process.


a. Twin screw extruder equipment


Using this equipment, we can directly feed the wet amorphous polymer chips into the extruder. Crystallization equipment or drying equipment for polyester chips is no longer needed. The extruder also has good polymer mixing properties. For polypropylene spinning, the extruder can use various dyed chips to spray or mix, and the twin-screw extruder is also very efficient.


b. Electric heating is adopted for all extruders, polymer production lines and spinning beams, which can provide clean, high-precision and wide-range temperature control.


c. Spinning beam of sufficient width and spinneret with 8 built-in spinneret pumps.


d. The spinneret quenching with both sides at atmospheric pressure can freely change the operating state.


e. Stretching nozzle with sufficient width. It can change the filament direction and spinning speed at will.


f. As for the bonding, you can choose electric heating thermal bonding or oil heating thermal bonding according to customer requirements.


Due to these improvements, its current equipment has:


(1) The ability to process a variety of polymers: polypropylene, polyester, polyamide, etc.;


(2) Spinning ability of fine denier and superfine fiber, the range of coarse denier is 0.7-10 denier;


(3) High-speed spinning range, 5000 m/min for polyester and 3,500 m/min for polypropylene;


(4) The maximum production speed of high-speed fiber web is 500 m/min;


(5) The product has excellent uniformity. 


Spunbond products are widely used in medical and sanitary products, disposable anti-fouling clothing, agricultural harvest cloth, rice seedling floppy disks, agricultural ginseng special shed cloth, livestock greenhouses, furniture cloth, shoe lining, automotive interior materials, geotechnical Used cloth, new waterproof membrane, tourism and daily civilian products, coated fabric base cloth, etc.