JPS6346185B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a single web as a whole by overlapping two webs made of continuous filaments. In recent years, a method for producing nonwoven fabrics called the so-called spunbond method has been developed, in which a continuous filament extruded from a spinneret is stretched and transferred using an air sucker, a web is formed on a conveyor, and the webs are joined by thermocompression bonding or needle punching. , and nonwoven fabrics are actually produced using it. In this spunbonding method as well, attempts have been made to arrange spinnerets and air suckers in two or more rows and to laminate groups of filaments for various purposes. As a method of obtaining one web by this lamination, the first layer is formed on a net conveyor made of wire mesh, as described in Japanese Patent Publication No. 19427-1984 and Japanese Patent Publication No. 26584-1973. A method has been used in which a group of continuous filaments transported by an air suction car are sequentially laminated on top of the first layer of the web. Since it is necessary to form a web without any disturbance, we have taken measures such as increasing the amount of air sucked into the suction duct installed under the conveyor and minimizing the amount of accompanying high-speed air. In this case, there are disadvantages such as the first layer of web being blown away and the web being unable to be formed, and the width of both ends of the web being difficult to control, resulting in a large amount of end loss. On the other hand, as described in Japanese Patent Publication No. 54-17875 and Japanese Patent Application Laid-Open No. 48-50079, a second layer of web is formed on a rotary drum or a net conveyor having a porous surface. Invert the
A method was proposed in which the webs were overlapped on the web conveyor that was forming the first layer of web, but with this method, it was possible to overlap even high fabric weights without the web being blown away.
Even this has the following drawbacks. One drawback is the problem of net damage due to the use of a net conveyor. The net conveyor used here uses a drive roll coated with a rubber-based resin to drive the net and circulate it, but the drive roll and the net circulate by creating frictional resistance due to tension. Slips inevitably occur, and the net itself has the disadvantage of being worn out, or depending on how the tension is applied, the net may meander or tear at the seams, and this wear and damage can cause the wire of the wire that makes up the net to break. is,
If the web gets caught on the tip of the wire and gets bent or torn, the web will not only become useless as a product, but the net will have to be replaced. The reality is that such wear and damage become more severe as the speed of the conveyor increases, and the number of net replacements increases dramatically, significantly reducing production efficiency and causing replacement costs. Another disadvantage of this method is the quality problem in that the web thus obtained is almost completely separated into two layers. This is because the two layers are simply superimposed and in contact on two sides. For this reason, in bonding in the post-process, whether using an adhesive or heat-pressing, it is necessary to bond the two layers more firmly than with normal bonding so that the two layers do not separate. This firm bonding involves using a large amount of adhesive and heat-pressing at high temperatures. Therefore, the resulting web has the disadvantage of inevitably having a hard texture. The present inventors have found that the use of only a rotating drum is most suitable for improving the defects of the web caused by the wear of the wire mesh of the net conveyor, and furthermore, one web can be peeled into two layers. As a result of various studies on the process of overlapping webs that do not occur, we surprisingly found that by overlapping webs formed on two rotating drums at a certain point of contact, the web obtained can be separated into two layers. The present invention was achieved by discovering that it is difficult to do so. That is, in the present invention, a web consisting of continuous filaments extruded from a spinneret and stretched by an air sucker is formed on two porous rotating drums having porous surfaces and rotating inwardly to each other, and It is an object of the present invention to provide a method for manufacturing a web characterized in that two webs are overlapped near the point where they are closest to each other. To explain the present invention using drawings, FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view thereof. The two rotating drums 1 and 2 rotate inward from each other as indicated by the arrows in the figure, and their surfaces are made of porous material. As the porous material, a wire mesh, a punching plate, or a combination thereof can be used. A device having a punching plate as a base and covering it with a wire mesh has excellent precision and durability of the device, and is convenient for increasing speed. Furthermore, when forming a web from a continuous filament, high-speed air is inevitably involved, so it is necessary to provide an internal suction duct connected to a suction fan, but these can be installed within a range suitable for web formation. As described above, in the present invention, since only the rotating drum is used to form the web, there is no problem of wear of the wire mesh as in the case of a web conveyor, and therefore, there is no possibility of the web becoming twisted or torn. It is. The webs 3 and 4 formed on the rotating drums 1 and 2 are rotated inwardly toward each other as the drums rotate, and are overlapped near the point where they approach each other, but surprisingly. The web superimposed in this way is
It was found that unlike the web obtained from the combination of a drum and a net conveyor, it was difficult to separate the two original webs. If you think about it, at the same time that the web is superimposed on the rotating drum,
It is presumed that this is due to the surface portions being compressed as they penetrate into each other. These situations are explained in the third
To explain this with reference to the drawings and Fig. 4, Fig. 3 schematically shows the overlapping of webs made up of a combination of a web conveyor and a rotating drum, and Fig. 4 shows the superimposition of a web consisting of a combination of a web conveyor and a rotating drum. This diagram schematically shows the superposition of . In FIG. 3, the web 6 on the net conveyor 5 does not undergo any phase change due to the overlapping, and only the web 8 on the rotating drum 7 is compressed. In this case, it is thought that there will be no interaction with the other party at all. In this regard, when the webs on the rotating drums 9 and 10 are overlapped as shown in FIG. 4, both are compressed, so if the webs are compressed with their respective surface layers entrapped, they will peel off from each other. It is assumed that there will be resistance. In any case, the web obtained by the present invention is
It is difficult to separate into two layers and can be transferred stably to the next process. Of course, in order to perform this transfer stably, it is preferable to make the two rotating drums contact each other so that they can pressurize each other, since the webs overlap and are pressurized at the same time, which further promotes the fixation of the webs in addition to the above-mentioned entanglement effect. . To apply this contact pressure,
This can be achieved by fixing one rotating drum and pressing the other rotating drum against it using, for example, an air cylinder. In this case, a pressing pressure of 5 kg/cm is sufficient. The webs 3 and 4 made of continuous filaments are made of thermoplastic synthetic fibers such as polyethylene terephthalate, nylon-6, nylon-66, polypropylene, etc., especially nylon-6.
Polypropylene is preferable because the filament itself has viscoelasticity and is difficult to peel off even if slightly entangled. Since the web obtained in this way has entanglements, bonding can be performed under almost the same conditions as when joining a normal web consisting of only one layer, and there is no separation into two layers. A web with a soft texture can be obtained. Next, the present invention will be explained with examples. Example 1 A process using the spunbond method was carried out using a rectangular spindle with a length of 1 m in the width direction, a hole diameter of 0.25 mm, and 1000 holes, and a rectangular sucker with a length of 1 m installed below it.
Two rotating drums with a diameter of 800 mm are arranged parallel to each other, and their surfaces are covered with 5-mesh and 25-mesh wire meshes, with their surfaces facing each other. They were installed so that they were in contact with each other and could be pressurized with an air cylinder. Furthermore, a calender roll consisting of two rolls having an embossed pattern on one of which can be heated is arranged directly below the roll, so that the web transferred from the rotating drum can be partially thermocompressed. In this process, poly-ε
- Caprolactam is extruded at 90Kg/hr per spinneret, stretched and transferred with an air suction car, and the circumferential speed is
Each web was formed on a rotating drum rotating at 30 m/min, and the webs were overlapped near the point where they came closest to each other, and at the same time, the rotating drums were pressed together at a pressure of 1 kg/cm. Next, a web of 100 g/m ² was obtained by thermocompression bonding between calender rolls whose surfaces were heated to 150°C. During the production of this web, no breakage or tearing occurred, and it was stable even during long-term operation. Moreover, the obtained web did not peel into two layers. Comparative Example Using the same spindle and the same air sucker as in Example 1, the filament from one spindle was placed on the net conveyor and the filament from the other spindle was placed on the same rotating drum as used in Example 1. above,
Each web was formed, and the web on the rotating drum was rotated to overlap the web on the net conveyor, and then heated and pressed using the same heating roll as in Example 1. At this time, the polymer used was poly-ε-caprolactam, and the extrusion amount was 90 kg/1 spindle.
The speed of hr, net conveyor, and rotating drum is
The speed was 30m/min. Also, the surface temperature of the heating roll
Bonding was carried out under the same conditions as in Example 1 at 150°C. The web thus obtained is 100g/m ²
The following items were measured using the 100 g/m ² web obtained in Example 1. Measurement results first
Shown in the table.

[Table] The reason why the value of the comparative example is low is that peeling occurs between the two layers during the measurement. Example 2 Using a spindle with a pore diameter of 0.40 mm and 800 holes, and using the same equipment as in Example 1, polypropylene was extruded at 50 kg/hr, stretched and transferred with an air sucker, Each web is formed on a rotating drum rotating at a circumferential speed of 55 m/min, and a weight of 1 kg/min is formed.
They were overlapped and thermocompressed using a heated roll heated to 125° C. while applying a contact pressure of 1.5 cm. The obtained web is
At 15 g/m ² , it was no different from the web obtained from a single sheet. Further, during production, there was no occurrence of crinkling or tearing, and there was no problem in transferring from the rotating drum to the heating roll. As described above, by the manufacturing method of the present invention,
This made it possible to achieve stable, high production without web peeling.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view thereof. FIG. 3 is a schematic diagram of the conventional method of overlapping webs, and FIG. 4 is a schematic diagram of the conventional method of overlapping webs on the rotating drum of the present invention.

Claims (1)

[Scope of Claims] 1 A web consisting of continuous filaments extruded from a spinneret and stretched with an air sucker is formed on two porous rotating drums having porous surfaces and rotating inwardly to each other, and A method for producing webs, characterized in that two webs are overlapped near the point where they are closest to each other. 2. The method for producing a web according to claim 1, wherein the continuous filament extruded from the spinneret is nylon-6 or polypropylene.