JPS6094663A - Opening of filament group - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for opening a group of filaments.

More specifically, the present invention relates to a method of applying an extremely high static electricity to a group of filaments to properly open the group of filaments.

Conventionally, in the method of making a nonwoven fabric by dispersing and depositing multiple filaments sent with an air flow on a net conveyor, in order to obtain a high quality nonwoven web, it is necessary to completely separate the filaments from each other (called opening). needs to be done. As a method for this, a technique is generally used in which a group of filaments is given static electricity by contact charging due to friction and collision or charging by corona discharge, and each filament is opened by mutual repulsion between the filaments to form a uniform nonwoven web. There is. However, the problem with the electrostatic opening techniques known so far is that the amount of static electricity applied to the filaments is still insufficient, making it impossible to obtain a satisfactory opening state. In particular, when the number of filaments is increased, the amount of static electricity applied to the filaments is insufficient, and a good opening state cannot be obtained. The present inventors have published Japanese Patent Publication No. 44-21817 or Japanese Patent Publication No. 54-285.
We focused on the fact that the method of passing a group of filaments through a corona discharge electric field and charging the group of filaments by corona discharge, which is disclosed in Publication No. 08, etc., provides a stable and relatively good opening state, and we studied this method. However, even with this method, the amount of charge was insufficient and the opening state was not satisfactory.Especially when the number of filaments increased, the opening state deteriorated significantly, and from a few filaments to more than 1000 filaments. There is a problem in that some filaments are deposited in bundles without being opened, resulting in extremely poor uniformity and quality of the resulting nonwoven web.

In general, the spreadability is greatly influenced by the magnitude of the electrostatic repulsion between filaments, and therefore, it can be said that the higher the amount of charge, the greater the electrostatic repulsion and the better the spreadability.

The opening itself is due to the balance between the electrostatic repulsion between the filaments and the filament tension generated by the accompanying airflow, so the band 1! It can be said that increasing the amount of L to increase the electrostatic repulsive force between filaments and reducing the accompanying airflow and lowering the filament tension are ways to improve fiber opening, but the number of filaments in the filament group is approximately In order to obtain good opening when charging a group of filaments with a spatial density of more than 50 filaments, with a spatial density of approximately 50 filaments/cm'' in the cross section of the filament group just before entering the corona discharge electric field, using conventional techniques, In addition, even if you try to reduce the accompanying airflow and lower the filament tension to make it easier to open the filament, the filament will come into contact with the target electrode and will not lose its charge.On the contrary, the amount of charge will decrease and the filament will not lose its charge. The drawbacks of the conventional technology, such as poor fiber opening, become clear.

In view of these points, the inventors of the present invention have conducted intensive studies to impart a high charge amount to a filament group consisting of a large number of filaments, and to stably obtain an extremely good opening state with high productivity.As a result, the present invention has been developed. has been completed.

That is, the present invention provides a method for opening filaments by passing the filaments together with an air flow through a corona discharge electric field consisting of a corona discharge electrode and a target electrode to apply static electricity to the filaments. A method for opening a group of filaments, which is characterized by passing a group of filaments through a corona discharge electric field in which an air curtain flow is formed and opening the filaments, and a corona discharge electric field that allows the corona voltage to be adjusted arbitrarily. Consisting of a plurality of corona discharge units, the distance between the corona discharge electrode and the target electrode of each unit that forms a corona discharge electric field increases in the traveling direction of the filament group for each unit, and Corona discharge, where an air curtain flow is formed.

This is a method for opening a group of filaments, which is characterized in that the group of filaments is opened by passing the group of filaments in an electric field.

The present invention is a novel method of passing a group of filaments through a corona discharge electric field in which an air curtain flow is formed along a target electrode of a corona discharge unit. A high charge amount and an extremely favorable fiber opening state, which could not be obtained by other methods, can be easily obtained with high productivity, and the effects are extremely large.

The present invention will be explained in more detail below.

The filament group as used in the present invention refers to a plurality of filaments, and may be in a bundle, in a tape-like or ribbon-like state in which the bundle is thinly spread out, in a sagging pattern where the single fibers are arranged almost uniformly, or in a random manner. They may be arranged at regular intervals. The filament is made of a so-called filament-forming material, and includes synthetic fibers such as holamide, polyester, polyolefin, and polyacrylonitrile, recycled fibers such as rayon, and inorganic fibers such as glass fiber. The filaments may be composite fibers or mixed fibers made of different components, and may have any diameter. The filaments are guided into the corona discharge field by an air stream passing through the corona discharge field, typically by an air sucker, aspirator, or the like.

In the present invention, the filament group is charged by being passed through a corona discharge electric field together with an air flow.
, is the ilt world. The filament group is charged by corona discharge, and each filament receives electrostatic repulsion from each other.
Corona radiation shows a tendency to spread throughout the world. Furthermore, since the sign of the charge generated from the corona discharge 111 pole matches the sign of the charge on the filament group, the filament group is drawn toward the target electrode due to the electrostatic repulsion. When the charged filament comes into contact with the target electrode, a portion of the charge held by the filament is lost, the amount of charge reaches a ceiling, and the amount of charge necessary for obtaining good fiber opening cannot be obtained. In addition, even if the charged filament group comes into contact with the target electrode, when it reaches a certain distance, the filament group and target it
The electric field generated between the t-poles causes a discharge, and a phenomenon occurs in which a portion of the electric charge on the filament group is lost. Especially when there are many charge meters in the filament group, the discharge distance becomes long and the charge due to discharge is t%! Load escape is likely to occur. Therefore, in order to prevent contact between the filament group and the target electrode, furthermore, to maintain a distance between the filament group and the target electrode and prevent the dissipation of the electrical charge on the filament group, an air curtain flow is applied to the target electrode. It is important that it is formed. Another effect of this air curtain flow is that when the charged filaments collide with a collision plate, etc., in order to spread the filaments more effectively or spread the filaments further, the collision of the filaments The collision force against the plate increases, and the fiber opening and the widening of the filament group become more effective. Surprisingly, it has been found that in such a case, the amount of charge on the filament group further increases, and the opening of the filament group becomes even more effective. The air curtain stream is formed by air injection nozzles. The air injection nozzle has a slit shape.
Although the shape may be arbitrary, such as a circular shape, it is selected in order to obtain the required air curtain flow according to the shape of the target electrode. For example, if the target electrode is a flat plate electrode, the entire surface of the target electrode is removed. A slit-shaped 9- jet sprayed from a nozzle is preferred.

Preferably, the air curtain flow is along the target electrode. For example, perpendicular to the filament group,
Alternatively, an air curtain flow in the direction of moving the filaments away from the target electrode may have some effect if the flow velocity and flow rate are small, but this will make the running state of the filaments in the corona discharge electric field unstable and corona This is not preferable because it causes instability in charging due to discharge, which in turn makes the opened state of the filament group unstable. The air curtain flow is usually formed by supplying compressed air, but the pressure, flow rate, flow rate, etc. of the air curtain flow may be set arbitrarily to obtain good fiber opening.

In the present invention, the corona discharge electric field is composed of a plurality of co-discharge units whose corona voltage can be set arbitrarily, and the distance between the corona discharge electrode and the target electrode of each unit forming the corona discharge electric field is adjusted for each unit. The method of opening a group of filaments by passing them through a corona discharge electric field in which an air curtain flow is formed with an air curtain flow increasing in the traveling direction of the group of filaments and reaching the target electrode of the final corona discharge unit is as follows.
This is especially effective when the number of filaments constituting the filament group and the spatial arrangement density of the filament group in the cross-sectional direction are increased. With multiple corona discharge units, the amount of charge on the filament group decreases as the number of filaments in the filament group increases and the speed of passage of the filament group in the corona discharge electric field increases. This is particularly preferable when it becomes impossible to impart the amount of charge necessary to obtain a good opening state to the filament group. In addition, the fact that the distance between the corona discharge electrode and the target electrode of each unit increases in the traveling direction of the filament group is due to the electrostatic repulsion of each filament as the filament group passes through each unit and is charged. The spread becomes larger, and the electric charge generated from the corona discharge electrode and the filament (filamen) also have electrostatic repulsion because the signs of the charged charges match, and each time it passes through each unit, the electrostatic repulsion increases. It is necessary to prevent the filament group from coming into contact with the target electrode as the amount increases and to prevent the contact between the filament group and the target electrode, to prevent the electrical charge of the filament group from escaping, and to further charge the filament group by corona discharge. . In addition to this, the fact that the corona voltage of each unit can be adjusted independently and arbitrarily means that the corona current value of each unit can be adjusted. Since the corona current value set for each unit to obtain a certain level of charge also changes, it is made up of independent units that can arbitrarily adjust the corona voltage to impart a high charge of 4 degrees to the filament group. It is preferable. The voltage of each corona discharge unit, that is, the corona current value, and the number of independent units are determined by the number of filament groups, the total denier, the spatial density in the cross-sectional direction, the speed of passage of the filament groups in the corona discharge electric field, and the number of independent units. It may be arbitrarily set to obtain a high charge amount depending on the flow rate, flow rate, etc. of the conveying air flow. The distance between the corona discharge electrode and the target electrode of each unit that forms a corona discharge electric field increases in the traveling direction of the filament group for each unit.1. However, as a method of increase, the corona discharge electrode and the target electrode of each unit are arranged on a common plane, and the distance between the arrangement planes increases continuously in the traveling direction of the filament group, For example, the corona discharge electrodes of each unit are distributed on a common plane, and the target electrodes are gradually increased in the traveling direction of the filament group for each unit. The discharge electrodes are arranged on a common plane parallel to the running axis of the filament group when they enter the corona discharge electric field, and the target electrodes are gradually increased in the running direction of the filament group for each independent corona discharge unit. What is there is good. Father, this step is 2 to 20 meters.
The length is preferably 2 to 10 m, but is not limited thereto. The corona voltage of multiple independent corona discharge units can be adjusted by connecting each unit to a separate high voltage generator, or by connecting the high voltage generator to the corona discharge electrode of each corona discharge unit. It may be selected arbitrarily, such as by providing a variable resistor.

The corona discharge method used in the present invention may be any conventionally known method; for example, Japanese Patent Publication No. 44-21817
As disclosed in Japanese Patent Publication No. 54-28508, a corona discharge method consisting of a needle electrode and a planar or curved electrode is generally preferable, and a corona discharge method using a needle-shaped electrode and a planar or curved electrode is generally preferable. A voltage of 10 to 60 KV is applied to create a state in which a corona current is generated, and a group of filaments is passed between the electrodes. In this case, an array of needle electrodes,
It is possible to form various electric fields depending on the shape of the planar electrode, the distance between the two electrodes, and the voltage, and any electric field may be adopted. As electrodes for corona discharge, in addition to such a combination of a needle electrode and a planar electrode, combinations of a needle electrode and a needle electrode, a planar electrode and a planar electrode, and a rod-like electrode and a rod-like electrode may be adopted. Preferably, the corona discharge electrode of each unit is a needle-like electrode, and the target electrode is a flat electrode. In addition, the needle electrode of each unit is preferably composed of a plurality of needles in order to advantageously charge the filament group.
The number of constituent needles and the arrangement of needles may be set arbitrarily.

In the present invention, the filaments are charged and opened by passing through a corona discharge electric field together with an air flow, but the method for depositing the opened filaments to form a wide nonwoven web is as follows: You can deposit it as is, or
After the corona discharge treatment, the filaments may be further spread out and deposited by colliding with a collision plate. Alternatively, any method may be used, such as applying oscillation in the direction of the OD force, spreading the particles, and stacking them. In particular, the effects of the present invention are further exhibited when the filaments are further spread out by colliding with a collision plate after the corona discharge treatment. That is, the number of charged caps of the filament group increases and the spreadability becomes even better.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of the method for opening a filament group according to the present invention, in which a filament group 2 ejected from a spinneret 1 is taken up by an air sucker 3, and the ejected filament group is As illustrated in FIG. 3, after being charged by passing through a corona discharge electric field region consisting of a needle electrode 4 and a flat plate electrode 5 connected to a DC high voltage power source 6, the needle electrode 7 is further connected to a DC high voltage power source 9. The nonwoven web 12 is formed by a flat plate electrode 8, passed through a corona discharge electric field area formed by an air curtain flow 11 on the flat plate electrode 8, charged, spread, and deposited on a net conveyor 11. It is something that forms. In addition, the corona discharge electric field composed of the needle electrode 4 and the flat plate electrode 5 is particularly affected by the increase in the number of filament groups.
If charging only by corona discharge of the needle electrode 7 and the plate electrode 8 is insufficient to provide static electricity necessary for fiber opening, it is effective and does not need to be operated unless necessary.

FIG. 2 shows another embodiment of the present invention, in which a group of filaments drawn or drawn by high-speed rotating rolls 13 and 13' are transferred to a needle electrode 4 by an air sucker 3'.
', the flat electrode 5', the needle electrode 7', the flat electrode 8', and the flat electrode 8' are guided through a corona discharge electric field formed by an air curtain flow 10', charged, and opened. It forms a nonwoven web with

The present invention relates to a method of introducing and charging a group of filaments into an electric field generating a corona discharge, and opening the group of filaments well. As a result, a high-quality, well-opened nonwoven web can be obtained extremely easily and stably. As shown in the following examples, the present invention solves the problem of poor opening properties and instability caused by the low charge amount of a filament group consisting of multiple filaments, which was not solved in the prior art. By implementing the present invention, productivity can be increased, and the present invention is extremely useful from an industrial standpoint. The present invention may be used not only as a method for manufacturing such a spread nonwoven web but also for various types of fiber spreading for mixed fibers and other purposes.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited thereto.

In addition, the amount of charge in the examples was measured with a charge amount needle (KQ-431B type, Kasuga Denki Group).

17- Example 1 Polyethylene terephthalate was discharged through a spindle having 120 holes by the method shown in FIG. Of
Air sucker placed at f+ position (pressure 4. OK 4
/cm"G, flow rate 35 Nm"/hr), and a filament group with a single yarn of 1.5 d was obtained. The yarn speed of the filament group at this time was converted to 4800 ml/min.

A solar discharge device as shown in Fig. 3 was set 5 m below the air soccer. The needle-shaped corona electrodes 4 and 7 each have seven needles, arranged in a common plane parallel to the axis of entry of the filament group, and connected to independent DC high voltage generators. The flat plate electrode 5 made of SUS is placed at a distance of 17 IllI from the needle corona electrode 4, and the flat plate electrode 8 made of 8U8 is placed at a distance of 21 inches from the needle corona electrode 7.
are placed at a distance of Moreover, a slit nozzle (1.5 cm x 60 m) for air injection is installed on the top of the flat electrode 8.
) is provided. The filament group was passed through this corona discharge device, and the air pressure supplied to the slit nozzle was varied at a voltage of -52 KV for the first stage corona discharge unit and -41 KV for the second stage corona discharge unit. It was changed, charged, and deposited on a net conveyor.

The results are shown in Table 1, and the deposited nonwoven webs each had a charge amount of 20 μc/f or more, and there were no bundles of filaments, and each filament was opened well to form a single filament. It was a non-woven web. In addition, the amount of charge increased as the supplied air pressure increased.

Table 1 Comparative Example 1 The operation of Example 1 was repeated using 10 needle-like electrodes and 8 U S plate-like electrodes, and the electrode spacing was set to 17.
When carried out at various voltages using a corona discharge unit with only stages, the results all resulted in poor quality nonwoven webs with bundles of filaments present throughout the nonwoven web. The maximum charge amount of the filament at this time was 10 μc/l.

Example 2 By the method shown in Fig. 2, polyethylene terephthalate was discharged through a spindle with 180 holes, taken up by a pair of high-speed rolls at a yarn speed of 5,000 m/min, and then placed in an air sucker (pressure 4, OKp). /cm2G, flow rate 35Nm/hr), and the single yarn was 2. A group of Od filaments was obtained.

A corona discharge device of the same type as in Example 1 was set at a position 5 m+ below this air sucker, and the corona current value of each unit was varied by setting the pressure of the supplied air to form an air flow to 2/α2G. The filament group was charged. The results are shown in Figure 4, and the maximum charge amount is 0.35 mA for the first stage corona discharge NEET.
The current value of the second stage corona discharge unit is 0.30mA
At that time, it showed 26μc/l. Even without performing the first stage corona discharge, the filament showed 16 μC/fk, and the filament with a charge amount exceeding 14 μc/l was a nonwoven web with extremely good opening.

Comparative Example 2 The operation of Example 2 was repeated when the needle-shaped corona electrodes 4 and 7 of the corona discharge device used in Example 1 were connected to the same power source, and the plate-shaped target electrodes (poles 5 and 8 were on the same plane). The experiment was carried out using a corona discharge device with no air flow, in which the needle-shaped corona electrodes 4 and 7 and the flat plate-shaped target electrodes 5 and 8 faced each other at an equal distance of 17 mm and were placed over the target electrodes. The results are shown in Figure 4, and the maximum charge amount was 12 μc.
/f was obtained, and the obtained nonwoven web was also of poor quality with bundles of filaments existing everywhere.

Examples 3 to 7 The operation of Example 2 was repeated using single yarn 2. The number of filaments in the Od filament group was varied. Table 2 shows the maximum charge amount obtained and the fiber opening state at that time.

21-Table←2 Example 8 Polyzolopyrene (Chisso Corporation 8
5056), was discharged from a spinneret with 96 holes, passed through a pair of high-speed rolls, and taken off at a yarn speed of 5000 m/min to obtain a filament group of 2 d of single yarns.

Air sucker (pressure 4. OK 4)
/crn"G, flow 3135 Nm"/hr), a corona discharge device of the same type as in Example 1 was set at a position 5 m below this air sucker, and the filament group was passed through to discharge the first stage corona. The voltage of the discharge unit is -32, the voltage of the second stage corona discharge unit is -45KV,
The filament was deposited on a net conveyor by charging the supply air at a pressure of 22-2 Ky/crn''G to form the air flow. It was a nonwoven web opened into threads.

Example 9 After corona discharge treatment in the same manner as in Example 1, an insulated copper flat plate was installed at an angle of about 45 degrees at a position of about 50 degrees on the lower blade of the corona discharge treatment device, and the filament group was collided with this plate. is spread and deposited to form a nonwoven web, and as the pressure of the supply air increases to form an air flow,
Web width has also increased. Furthermore, the amount of charge increased as the pressure of the supplied air increased. The results are shown in Table-3.

Table-3

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are schematic diagrams showing examples of embodiments according to the present invention. FIG. 3 is a sectional view of a specific example of the corona discharge device of the present invention. FIG. 4 shows the results of the lower corona current value and charge amount of Example 2 and Comparative Example 2. 1... Spinneret, 2... Filament group, 3.3'...
・Air sucker, 4.4'...needle electrode, 5,5'
...Plant electrode, 6.6'...DC high voltage power supply, 7
, 7'... Needle electrode, 8.8'... Flat electrode, 9
．． 9'...DC high voltage power supply, 10.10'...Air flow fixed to flat electrode, 11...Net conveyor, 1
2... Nonwoven web, 13, 13'... Rotating roll. Patent applicant: Asahi Kasei Kogyo Co., Ltd. Figure 3 Figure 4 Lower I included flow 1 Denno I direct

Claims (5)

[Claims] (1) In a method of spreading filaments by passing a filament together with an air flow through a corona discharge electric field consisting of a corona discharge electrode and a target electrode and applying static electricity to the filament, an air curtain flow is formed along the target electrode. A method for opening a group of filaments, characterized by passing the group of filaments through a corona discharge electric field and opening the group. (2) The corona discharge electrode that forms the corona discharge electric field is a needle-shaped electrode (Tagera)! A method for opening a group of filaments according to claim 1, wherein the pole is a flat electrode. (3) In a method of spreading a filament group by passing the filament group together with an air flow in a corona discharge electric field and applying static electricity to the filament group, the corona discharge electric field is composed of a plurality of corona discharge units whose corona voltage can be arbitrarily adjusted; And the corona discharge 'a of each unit that forms the corona discharge electric field.
The distance between the t-pole and the target electrode increases unit by unit in the running direction of the filament group, and the filament group is passed through a corona discharge electric field in which an air curtain flow is formed along the target electrode of the final corona discharge unit, A method for opening a group of filaments, which is characterized by opening the filaments. (4) The method for opening a group of filaments according to claim 3, wherein each unit corona discharge electrode that forms a corona discharge electric field is a needle-like electrode, and the target electrode is a flat plate-like electrode. (5) The flat electrodes are stepped in the running direction of the filament group, and the final flat electrode starts from the step between the final flat electrode and the previous flat electrode! ! A method for opening a group of filaments according to claim 3, in which an air curtain flow is ejected along the polar surface.