JPS596942B2 - Manufacturing method of nonwoven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a process for manufacturing a nonwoven fabric with uniform fiber density, flexibility, and excellent economy. The present invention relates to a method of collecting and depositing the particles while preventing the particles from being wrapped around the rolls.

In general, the individual fibers deposited on the collection conveyor are straight or slightly curved, and do not have any enveloping properties between the fibers, but are simply layered on top of each other, so there is a slight The deposited fiber layer easily collapses and loses its uniformity due to external forces, such as the driving of the collection conveyor.

Various methods have been tried to solve these drawbacks.

For example, the deposited fiber layer is stabilized by installing a gas suction device on the back side of the collection conveyor and sucking in an amount of gas several times the amount of fluid that is ejected onto the conveyor together with the fibers. However, the drawback of this method is that once the uniformly deposited fiber layer is transferred by the drive of the collection conveyor, the suction device has an almost equal suction force over almost the entire area of the suction action. As soon as the end of the suction device is exceeded, the suction force is almost completely lost, causing a significant change in the suction force in the border region. Therefore, the deposited fiber layer that had maintained its shape is instantly released from the suction force, and the large pressure fluctuation causes a strong turbulent flow, causing the deposited fiber layer to collapse its shape in the boundary area. . For example, immediately after the fibers are deposited on a collecting conveyor with a high-speed airflow, a pair of feed rolls is pressurized and a heating medium is supplied to the rolls to stabilize the shape of the deposited fiber layer by heating it into a plate-like shape. However, in this method, relatively high-melting point fibers such as polypropylene fibers and polyester fibers are weakly heat-set at 100 to 120°C, resulting in a somewhat film rack. Limited to non-woven fabrics such as car mat packing materials.

Furthermore, if a non-film-like deposited fiber layer is to be obtained by using fibers with a relatively low melting point, such as polyethylene fibers, heating is not possible. Furthermore, when the continuous multifilament is separated by a plurality of jet-type air guns and discharged to a collection conveyor along with a high-speed air flow, static electricity is generated due to the friction of the threads. Therefore, when the fiber is pressed into a plate shape by a feed roll and the shape is maintained, the fiber layer is wound around the roll due to static electricity, making it impossible for the deposited fiber layer to pass through. The present inventors have arrived at the present invention as a result of intensive research in order to solve these problems and to collect and produce excellent fiber deposits. That is, when manufacturing a nonwoven fabric by spraying continuous multifilaments onto an air-permeable collecting conveyor, the present invention brings the suction-deposited fiber layer into contact with the deposited fiber layer of a feed roll provided within the suction area. This nonwoven fabric manufacturing method is characterized in that pressure treatment is performed using a pair of feed rolls whose surfaces have uneven portions, and the nonwoven fabric is further transferred under suction. After spinning, the split multifilament is blown onto an air-permeable collecting conveyor having a flexible structure such as a porous wire mesh. The collecting conveyor is equipped with a suction box at the bottom, and the blown multifilaments are sucked downward together with the air flow, thus forming a relatively uniform layer of deposited fibers. In order to take out this uniform deposited fiber layer as it is, it is necessary that no collapse occurs when the collection conveyor is driven, and for this purpose, a pair of feed rolls installed in the suction area as close as possible to the suction collection is required. Pressure treatment is required. In the present invention, of the pair of feed rolls, the surface of the roll that comes into contact with the deposited fiber layer must have irregularities and must not be smooth.

If a smooth roll is used, the deposited multifilaments are electrically charged and tend to wind around the roll, making it impossible to pressurize the deposited fiber layer. On the other hand, in the present invention, by using a roll having uneven portions, winding of the fibers around the roll can be completely prevented and sufficient pressure treatment can be performed. The roll having an uneven portion may be one whose surface is covered with a wire mesh, or the surface of the roll may be knurled, left and right thread grooved, or embossed to form an uneven surface.

Both the top and bottom surfaces of the roll may be made of gold-plated p-chrome plating.
It is preferable that the upper roll be plated with metal chrome and the lower roll made of rubber, since this will not damage the collection conveyor. The degree of pressure applied by the feed roll can be freely selected depending on the type of deposited fiber layer, the basis weight, and the purpose of the nonwoven fabric. The feed roll may be heated if necessary. In addition, by using a heated feed roll, it is possible to soften a part of the multifilament and bond the deposited fiber layer.
After pressure treatment with special feed rolls as mentioned above,
Furthermore, the deposited fiber layer is passed through a suction zone. As described above, if suction is stopped at the position where the pressure treatment is performed by the feed roll as in the conventional case, the deposited fiber layer may wrap around the roll surface at the position where it exits the feed roll due to the action of static electricity. Therefore, it is necessary to transport the deposited fiber layer while maintaining suction for some time after leaving the feed roll. By such means, any winding of the filament or deposited fiber layer onto the feed roll can be prevented. The size of the suction area after the feed roll varies depending on the type of deposited fiber layer, basis weight, transfer speed, etc.
Approximately 0.00 mm is desirable.

The deposited fiber layer that has passed through the suction area can be smoothly sent to the next process. FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the method of the present invention, in which a multifilament 1 separated by an air gun is sucked into a suction box 3 by a fan 6.
It is collected on a permeable conveyor belt 2 that moves over it.

The collected and formed deposited fiber layer 1' is transferred to the suction box 3
Pressure is applied by a pair of feed rolls 4 and 5 installed inside. The roll 5 that comes into contact with the deposited fiber layer 1' has irregularities on its surface.

The deposited fiber layer leaving the feed roll is further transferred under suction by moving over a suction box. The present invention will be explained below with reference to Examples.

Example 1 Nylon 6 was spun to a fineness of 5 denier using a melt extrusion spinning machine, separated into fibers by passing through an air gun, and collected using an apparatus as shown in FIG.

Feed roll diameter 200φMm) Collection conveyor speed 0.
5~5m/1nin, width 150C7rL) basis weight 50~
700V/m'' was collected without breaking the flexible deposited fiber layer.A 20-mesh wire mesh was wrapped around the upper roll of the feed roll to create an uneven surface.In this example, the fibers or fiber layer were collected by the upper roll due to static electricity. The phenomenon of winding up was not observed at all for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention.

Claims (1)

[Claims] 1. When producing a nonwoven fabric by spraying continuous multifilaments onto a collection conveyor with air permeability, the suction-deposited fiber layer is transferred to the surface of a feed roll provided within the suction area and in contact with the deposited fiber layer. 1. A method for producing a nonwoven fabric, characterized in that the nonwoven fabric is subjected to pressure treatment using a pair of feed rolls having uneven portions, and further transferred under suction.