The present invention relates to a method for producing a nonwoven fabric made of cellulose, especially a cellulose solution.
Cellulosic fibers and filaments are formed by spinning a solution of the cellulose amine oxide solvent followed by leaching in a dilute solution of water or an aqueous amine oxide to form cellulosic filaments which can then be cut into staple fibers. This extrusion and coagulation process is called solution spinning, and the solution spun cellulose fibers thus produced are generally called "lyocells".
It is possible to make smaller decitex fibres below 1.0 dtex by stripping the staple fibres. However, high costs and high energy consumption.
 how are non woven fabrics made

 The present invention provides an inexpensive and efficient process for making nonwoven fabrics containing low decitex cellulose fibers.
Therefore, the present invention provides a method for producing a cellulose nonwoven fabric made of fibers, the fiber being formed by extruding a solution of cellulose, passing it through at least one spinnerette, and extruding the fibers through the action of a high-speed airflow. Fine, fine fibers are collected on a surface, and the web is then solidified on this surface.
The term "gas" includes various kinds of steam such as steam.
The cellulose solution is preferably a cellulose solution using an amine oxide as a solvent, and is generally a N-oxide tertiary amine, especially N-methylmorpholine-N-oxide (NMMO). The cellulose solution may contain as little as 2% by weight of cellulose; however, the solution preferably contains 4 to 22% by weight of cellulose, with a cellulose degree of polymerization of 200 to 5,000, more usually 400 to 1,000.
In a preferred embodiment, the cellulose solution contains 15% by weight of cellulose, 10% by weight of water, 75% by weight of NMMO, and the cellulose has a degree of polymerization of about 600.
Microfibrils or fibrils formed by fiber refinement are collected on one surface and then solidified by water (also referred to as "regeneration") or dilute aqueous amine oxide solution containing up to 20% amine oxide in water.
The gas, preferably air or steam, is blown onto the extruded fibers at a rate of 125-155°C, preferably about 150°C, at a rate of 250-500 m.s-1 (m/s). The lower the cellulose content in the spinning dope, the lower the air temperature that can be used. When the cellulose content in the spinning solution is low, the air temperature can be reduced to nearly 100°C. The gas flow rate should be at least 50 times higher than the speed at which fibers are extruded from the spinneret, preferably 1,000 to 20,000 times the speed.
The air is blown toward the extruded fiber at an oblique angle, preferably 15-45[deg.] with respect to the axial direction of the extrudate, preferably about 30[deg.]. The gas flow can also be skewed at a second oblique angle with respect to the spinnerette, even if the gas flow axis and the fiber axis do not intersect, the gas flow is tangential to the surface of the fiber extrudate.

 how are non woven fabrics made
According to the present invention, there is provided simultaneously an apparatus for manufacturing a nonwoven fabric containing "lyocell" fibers, the apparatus comprising a spinning cap for extruding a cellulose solution during operation; and one or more gas nozzles equipped therewith The gas flow is directed to the extrudate to make the extrudate fine and to form fibrils; a support surface is provided to collect the refined extrudate; regeneration means to coagulate the fibrils on the support surface. The support surface provided is preferably a drum surface.
Because the fibrils or fibers are collected on the support surface before regeneration, the fibers in contact with each other can be bonded to each other.
Thus, the present invention also provides a "lyocell" nonwoven fabric in which fibers can be bonded together without adhesives.
Hereinafter, the present invention will be described in detail by way of examples with reference to the accompanying drawings.