JPH1072759A - Spunbonded nonwoven fabric manufacturing method and fiber opening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a uniform and high-quality nonwoven fabric excellent in openedness of the filament group. SOLUTION: In such a method that a continuous filament group 2 joined together following melt spinning of a thermoplastic resin is drawn by a high- speed air jet draft apparatus 33 and then opened, a filament density regulator 7 equipped with an air jet unit 18 is set up right under a corona discharge unit made up of a needle electrode 5 and flat plate-like target electrode 6 so as to open the filament group through making it adhere to the target electrode 6, and the basis weight of the resultant nonwoven fabric is continuously measured crosswise by the use of a relevant device 12 and control valves 17 to deal with partial unevenness of basis weight are automatically controlled, thus obtaining the objective uniform nonwoven fabric with favorable openedness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method and an apparatus for opening a group of filaments for producing a uniform nonwoven web. More specifically, the present invention relates to a method and apparatus for opening the filament group by forced charging and producing a uniform nonwoven web.

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a uniform nonwoven web by dispersing and depositing a group of filaments conveyed together with an air flow on a net conveyor, the filaments collide with the group of filaments, and are contact-charged by friction or forced by corona discharge. A technique is generally used in which static electricity is imparted by charging, and each filament is opened by mutual repulsion between filaments to produce a uniform nonwoven web. Generally, in order to obtain a uniform nonwoven web, it is necessary to completely open the filaments, and the opening is greatly affected by the magnitude of the repulsion caused by the static electricity between the filaments. Therefore, it can be said that the higher the charge amount, the greater the repulsive force due to static electricity and the better the fiber opening. It is also important whether or not the filament is uniformly charged. If the charge is not uniform, the spread of the filament is poor. Therefore, it can be said that uniformly increasing the charge amount is a method for improving the spread state.

The present inventors have noticed that the method of passing a filament group through a corona discharge electric field and charging the filament group by corona discharge provides a stable and relatively good spread state. A study was conducted to improve the spread. However, in the fiber opening method using corona discharge, the constituent fibers of the continuous filament group can be sufficiently dispersed individually.However, when the number of filaments increases or the running speed of the filaments increases, the filaments are not separated from each other. Since it is piled up on a net conveyor in a bundle of several tens or more without being completely opened, it is difficult to suppress the non-uniformity when the obtained nonwoven fabric is viewed over the whole.

In the case of using a high-speed air current pulling device having a narrow cross section and a wide rectangular cross section, advanced technology is required to uniformly inject the continuous filament group introduced in an interdigital shape with the high speed air current in the width direction. It will cost. For this purpose, it is necessary to finish the inside of the high-speed airflow traction device, particularly the shape of the injection port, with high precision, but this requires high technology for finishing and also increases equipment costs and maintenance costs. In addition, non-uniformity of the continuous filament also occurs due to dirt and thermal strain inside the high-speed airflow traction device during operation.

[0005]

DISCLOSURE OF THE INVENTION In view of the above situation, an object of the present invention is to provide an opening method and an opening apparatus for improving the opening of filaments and advantageously obtaining a uniform nonwoven web. Is to provide. The present inventors have paid attention to the above points, and further improved the opening of the filament group, and studied a method for obtaining a uniform nonwoven web.As a result, in the method of opening using corona discharge, The present invention has been completed by devising a method of applying blast air to a continuous filament group.

[0006]

Means for Solving the Problems The first aspect of the present invention is that a continuous filament group obtained by melt-spinning a thermoplastic resin from a spinneret is drawn and narrowed and drawn by a high-speed airflow pulling device. In a method of producing a spunbond nonwoven fabric, in which a group of interdigital continuous filaments conveyed together with an air flow from a traction device are guided to a corona discharge unit composed of a corona discharge electrode and a plate-like target electrode and spread.
At a position on the corona discharge electrode side downstream of the corona discharge electrode,
An air injection device having an air injection port arranged over the entire width of the filament group in the width direction, and a number of adjustment valves capable of partially adjusting the air amount of the air injection port in the width direction are provided. While the filament group is pressed against the flat target electrode side, the filament is opened by passing through the corona discharge electric field, and the air amount is partially adjusted in the width direction of the device by the adjustment valve to adjust the basis weight of the nonwoven fabric. This is a method for producing a spunbonded nonwoven fabric.

According to a second aspect of the present invention, in the first aspect, a downstream side of the corona discharge electrode is located on a corona discharge electrode side.
An air injection device that is arranged over the entire width in the width direction of the filament group and has a number of individually independent air injection ports, and a number of adjustment valves that can individually adjust the amount of air in the air injection ports is provided. A method for producing a spunbonded nonwoven fabric, comprising providing an air injection device having a continuous slit-shaped air injection port.

A third aspect of the present invention is the first aspect or the second aspect.
The invention according to claim 1, further comprising a device capable of continuously measuring the basis weight of the nonwoven fabric in the width direction, and adjusting the regulating valve in conjunction with a signal from the device to adjust the basis weight of the nonwoven fabric. This is a method for producing a nonwoven fabric.

A fourth aspect of the present invention is that a continuous filament group obtained by melt-spinning a thermoplastic resin from a spinneret is drawn and thinned by a high-speed airflow traction device, and is drawn together with the airflow from the high-speed airflow traction device. In an apparatus for manufacturing a spunbonded nonwoven fabric in which a group of interlaced continuous filaments to be conveyed is guided to a corona discharge unit composed of a corona discharge electrode and a plate-like target electrode and spread, a downstream of the corona discharge electrode is provided on the corona discharge electrode side. In the position, an air injection device having an air injection port arranged over the entire width in the width direction of the filament group, and an adjustment valve capable of partially adjusting the amount of air in the air injection port in the width direction are provided. The continuous filament group is passed through the corona discharge electric field while being pressed against the flat target electrode side to open the fiber. An opening device of the filament group, wherein partially adjusting the air amount.

According to a fifth aspect of the present invention, in the fourth aspect, a downstream side of the corona discharge electrode is located on a corona discharge electrode side,
An air injection device arranged over the entire width in the width direction of the filament group and having a large number of individually independent air injection ports, and a number of adjustment valves capable of individually adjusting the amount of air in the air injection ports is provided. An opening device for a filament group, which is provided with an air injection device having a continuous slit-shaped air injection port.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a spunbonded nonwoven fabric according to the present invention and a fiber-spreading apparatus will be described in detail with reference to FIGS. FIG. 1 is a schematic diagram showing an example of an apparatus used in the method for producing a spunbonded nonwoven fabric according to the present invention. A filament group 2 discharged from a spinneret 1 is thinned and drawn by a high-speed airflow traction device 3, and The filament group 2 injected with the air flow passes through a corona discharge electric field composed of a corona discharge electrode (needle-shaped electrode) 5 connected to a DC high-voltage power supply 4 and a flat plate-like target electrode 6 and is charged. . At this time, the filament group 2 passes through the corona discharge electric field while being in close contact with the flat target electrode 6 by the jet air from the filament density adjusting device 7 (the air jetting device 18 and the adjusting valve 17). By the filament density adjusting device 7, the density of the filament group is made uniform and the fiber is opened. After passing through the corona discharge electric field, it is deposited in the form of a non-woven web on the collecting conveyor 8,
The non-woven fabric 10 is thermocompression-bonded at a number of points by the hot embossing roll 9 and wound up by the winder 11.

A basis weight measuring device 12 is mounted between the hot embossing roll 9 and the winder 11. The basis weight of the entire width is calculated and processed by a computer 13, and this is processed via a controller 14 by a filament density adjusting device 7. Is automatically adjusted to perform the basis weight adjustment.

In FIG. 1, the spinneret used in the present invention has a large number (100 to 600) in the width direction in several rows (5 to 10 rows) in a filament flow direction within a rectangle having a width of about 500 mm to 3000 mm. It is desirable to use one in which the spinning holes are arranged, and the thermoplastic resin used is not particularly limited as long as it has a fiber morphology, but resins such as polypropylene, polyethylene terephthalate, polyethylene, and nylon are used. Alternatively, a mixture thereof, a copolymer, or the like can be used, and the diameter and the cross-sectional shape are not particularly limited.

A plurality of filaments are spun from a rectangular spinneret in an interdigital shape, and the filaments are guided into a corona discharge electric field by a high-speed air current pulling device 3 having a rectangular cross section, and pass along with the air flow. In the present invention, the filament group passes through the corona discharge electric field together with the air flow and is charged, but the corona discharge method used in the present invention includes:
Any conventionally known method may be used, and a corona discharge method including a corona discharge electrode (needle-shaped electrode) and a plate-shaped target electrode is generally preferred, and usually -10 to 10 mm between electrodes having an interval of 20 mm to 5 mm. A voltage of -60 KV is applied to create a state in which corona discharge occurs, and the filament group is passed between the two electrodes. At this time, the applied voltage of the corona discharge is a limit voltage at which arc discharge does not occur, and depends on the distance between the needle electrode and the flat target electrode. Therefore, it is generally preferable to apply a voltage before arc discharge.

The corona discharge electrode (needle electrode) of the present invention
5 is preferably composed of a plurality of needles or a plurality of rows of needles, in order to advantageously charge the filament group 2, and is particularly preferably configured with a needle density of 2 to 10 needles / cm ² .
If the needle density is less than ² filaments / cm ² , if the number of filaments is large, it is not preferable because charges for obtaining a good spread cannot be uniformly applied. Needle density is 1
If the number of filaments exceeds 0 / cm ² , an excessive charge is applied to the filament group, so that a discharge occurs between the filament group 2 and the flat target electrode, or a discharge occurs in the air. A phenomenon in which a part of the charge amount is lost is not preferable. The arrangement of the needles is not particularly limited, but is more preferably arranged in a staggered manner.

The material of the corona discharge electrode (needle electrode) 5 is
Any material having electrical conductivity may be used, and is not particularly limited. As the material of the flat target electrode 6 used in the present invention, a hard material is suitable in terms of durability and stability because the filament group collides at a high speed, and a metal such as iron, chromium, nickel, or stainless steel is suitable. Are preferred.

FIGS. 2 to 4 are schematic diagrams showing the filament density adjusting device 7 (air injection device 18 and adjusting valve 17) of FIG. FIG. 2 shows an example of the filament density adjusting device 7 of the present invention. The air injection device 18 is provided with a slit-shaped air injection port 15 over the entire width of the filament group 2 in the width direction.
No. 5 has a flow direction of 1 to 5 mm and a width direction that is larger than the width of the filament group. In addition, a number of air supply pipes each having an adjustment valve 17 are arranged in the width direction of the air injection device 18 so that the air flow can be injected as uniformly as possible in the width direction. In this figure, the slit-shaped air injection port 15 is a continuous and integrated injection port, but the shape is not limited to this. A slit-shaped injection port may be partitioned, and a large number of nozzle-type injection ports that are not slit-shaped may be arranged in the width direction. in short,
Air injection device 1 of filament density adjusting device 7 of the present invention
The device 8 may be any device capable of uniformly injecting air in the width direction of the filament group 2 and finely adjusting the amount of air partially in the width direction. The air flow is usually formed by supplying compressed air, but the pressure, the flow rate of the air flow, the flow rate and the like may be arbitrarily set in order to obtain a good spread.

The air thus injected has a function of bringing the filaments flowing out of the high-speed airflow traction device into close contact with the flat target electrode. When the filaments that are in close contact with the flat target electrode are charged by the corona discharge unit, the charged filaments float up from the flat target electrode surface, and when the lifted filaments come into contact with the metallic flat target electrode again. Part of the charge of the charged filament group is lost, resulting in poor opening. For this reason, it is necessary to bring the charged filament group into close contact with the tip of the flat target electrode. Therefore, the filament group is always brought into close contact with the flat target electrode by jetting an air stream.

The air injection device 18 is installed at a position downstream of the corona discharge electrode and on the corona discharge electrode side with respect to the filament group. In this case, immediately after the corona discharge electrode, a position that does not deviate from the plate-like target electrode or a position that deviates from the plate-like target electrode may be used. However, if it is installed too downstream, the effect of bringing the filament group into close contact with the flat target electrode surface is lost, so that it is provided within a range where this effect is not lost.

Further, a large number of regulating valves 17 arranged in the width direction of the filament group have a function of adjusting the density of the filament group 2, and the filament is dispersed by increasing the air flow at a place where the filament density is high. Conversely, by reducing the airflow at a place where the filament density is low, the density is increased and the filament density can be made uniform. Thus, it is possible to adjust the filament density over the entire width in the width direction.

Further, in FIG. 1, the basis weight is measured over the entire width of the nonwoven fabric 10 by a basis weight measuring device 12 installed between the hot embossing roll 9 and the winder 11, and is calculated by a computer 13, and is calculated based on the standard basis weight. Alternatively, when there is a place below the reference weight, a signal is sent to the controller 14 to open and close the regulating valve 17. That is, the density of the filament group 2 is adjusted by opening the adjustment valve 17 at a location higher than the reference weight and by narrowing the adjustment valve 17 at a location lower than the reference weight. Therefore, the nonwoven fabric 10 whose basis weight is continuously measured by the basis weight measuring device 12 is automatically adjusted to a certain standard basis weight over the entire width of the nonwoven fabric 10 by adjusting the adjustment valve 17 via the computer 13 and the controller 14. And a uniform nonwoven fabric can be obtained.

3 and 4 show another example of the filament density adjusting device of the present invention. FIG. 3 is a perspective view of the air injection device 18, and FIG. 4 is a view of the needle electrode 5 and the air injection device 18 from the filament side. In this example, the air injection device 18 is divided into an upper stage and a lower stage, and the upper stage is provided with a slit-shaped air injection port 15 in the width direction. This slit-shaped air injection port 15 has a flow direction of 1 to 5 m.
m, the width direction is greater than the width of the filament, air is supplied from both sides of the air injection device, and an air stream is injected as uniformly as possible in the width direction. As described above, the air flow jetted from there serves to always jet the air flow to bring the filament group into close contact with the flat target electrode 6. The lower stage is composed of a group of a large number of air injection nozzles 16 arranged at intervals in the width direction and an air adjustment valve 17 for individually adjusting the injection air amount of each nozzle. It functions to adjust over the entire width in the width direction. The interval between the plurality of air jet nozzles 16 arranged in the width direction is preferably about 10 to 30 mm. If the distance between the air jet nozzles 16 exceeds 30 mm, it is difficult to completely adjust the location where the filament density is very high. If it is less than 10 mm, the nozzle holes become too dense more than necessary, and equipment such as an adjustment mechanism is wasted.

As a device for adjusting the amount of injected air of the filament density adjusting device 7 of the present invention, an adjusting valve (flow rate adjusting valve) 17 such as a ball valve or the like is used. It is not something to be done. When supplying pressurized air from a large compressor pipe or the like, a main valve, a pressure reducing valve, or the like is installed as a valve 19 upstream of the regulating valve 17. The air pressure is preferably 1 to 5 kgf / cm ² G, and the air amount of each nozzle may be adjusted according to the density of the filament group ejected from the high-speed airflow traction device 3. The shape and diameter of the nozzle hole are not particularly limited as long as the density of the filament can be adjusted.

[0024]

【Example】

Example 1 A nonwoven fabric was manufactured using an apparatus as shown in FIGS. Rectangular spinneret (2,000 spinning holes, 10 rows, 200 holes in one row width direction, 10 rows in length)
Polypropylene was melt-spun at a discharge rate of 1 g per minute from a hole diameter of 00 mm and a hole diameter of 0.5 mm, and was thinned and drawn by a high-speed airflow traction device 3 having a rectangular slit. The filament obtained at this time had a denier of 2 deniers. Thereafter, a stainless steel (S) grounded to a corona discharge electrode (needle electrode) 5 having a needle density of 5 / cm ² connected to a DC high-voltage power supply 4 below the high-speed airflow traction device 3 (S
(Made of US304), a corona discharge unit having a distance between electrodes of 20 mm was installed at an angle of 45 degrees, and a corona discharge voltage of −20 KV was applied between both electrodes.
Is applied to open the filament group 2, and an air injection device 18 is attached at a position immediately after the corona discharge electrode so as not to deviate from the flat target electrode. The size of the slit of the air injection port 15 at the upper stage is 2 mm. × 1100 mm, and the air pressure is 3 kgf / c upstream of the regulating valve 17.
An air stream was injected as m ² G. Further, 51 air jet nozzles 16 in the lower stage are attached in the width direction at intervals of 20 mm (the numbers of nozzles in FIGS. 2 and 3 are reference).

The air pressure is set at a pressure of 3 kgf before the regulating valve.
/ Cm ² G. After that, it is deposited on the collection conveyor,
A non-woven fabric of 5 g / m ² was produced. At this time, the adjustment of the amount of air jetted from the lower air jet nozzle 16 of the air jet device 18 is performed by continuously measuring the basis weight by the basis weight measuring device 12, and the measurement result shows that the basis weight is high in the width direction of the nonwoven fabric 10. The location and the low location were specified, and the adjustment valve 17 was automatically adjusted via the computer 13 to adjust the basis weight.

Example 2 A nonwoven web was produced in the same manner as in Example 1 except that the weight of the basis weight measuring device 12 and the regulating valve 17 were not linked, and the regulating valve 17 was manually adjusted with reference to the data of the basis weight measuring device. Was manufactured. Embodiment 3 The air flow is not always injected from the air injection port 15 in the upper stage of the filament density adjusting device 7 (the air injection device 18 and the adjustment valve 17), but is always injected from all the injection nozzles 16 in the lower stage. The adjustment was performed in the same manner as in Example 1. Otherwise, a nonwoven web was produced in the same manner as in Example 1.

Comparative Example 1 A nonwoven web was produced in the same manner as in Example 1 except that the filament density adjusting device 7 (the air injection device 18 and the adjusting valve 17) was not installed. Comparative Example 2 A nonwoven web was produced in the same manner as in Example 1, except that the basis weight measuring device 12 and the adjusting valve 17 were not linked, and the air flow was not jetted from the air jet nozzle 16 at the lower stage of the filament density adjusting device 7. did.

The opened state of the nonwoven webs obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was visually observed. Also, after removing the obtained non-woven fabric 50 mm each ear, 25 m in the width direction
m, and cut into lengths of 500 mm in the flow direction, the individual weights were measured, the average value and the standard deviation were determined, and the CV value (%) was represented by the standard deviation / average value × 100. Table 1 shows the spread state and CV values of these obtained nonwoven fabrics.

[0029]

[Table 1]

As is apparent from the above results, the nonwoven webs obtained in Examples 1 and 2 hardly confirmed a state in which filaments were bundled into several tens of filaments, and showed a very good open state. A uniform, high quality nonwoven web was obtained. Further, those obtained in Example 3 were also second only to these. On the other hand, in the case of Comparative Example 1, the filament group that has been charged and expanded comes into contact with the flat electrode again,
Part of the charge of the charged filament group was removed, and bundles of filaments were present everywhere, so that it was not possible to obtain a good-spread nonwoven web. In Comparative Example 2, although a relatively good spread was obtained, a uniform nonwoven web having a poor CV value could not be obtained because the density of filaments could not be adjusted.

[0031]

According to the present invention, in the production of a nonwoven web in which a continuous filament group obtained by melt-spinning a thermoplastic resin and bundled is thinned and opened by a high-speed airflow drawing device, the interdigitated continuous filament group is corona-discharged. By passing the filament through a corona discharge electric field consisting of a (needle-shaped electrode) and a flat target electrode, and installing an air jet type filament density adjusting device directly below the needle-shaped electrode, the filament group can be more flattened to the flat target electrode. Since the fibers can be adhered to each other and the density of the filament group is adjusted in the width direction, the obtained nonwoven web has a good and uniform spread state.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a nonwoven fabric manufacturing process using the filament group opening method of the present invention.

FIG. 2 is a perspective view showing an example of a filament density adjusting device of the present invention.

FIG. 3 is a perspective view showing another example of the filament density adjusting device of the present invention, which is different from FIG.

4 is a view of the filament density adjusting device of the present invention shown in FIG. 3 and a needle-like electrode as viewed from the filament side.

[Explanation of symbols]

 1: Spinneret 2: Filament group 3: High-speed airflow traction device 4: DC high voltage power supply 5: Corona discharge electrode (needle electrode) 6: Flat target electrode 7: Filament density adjusting device 8: Collection conveyor 9: Heat Embossing roll 10: Non-woven fabric 11: Winding machine 12: Weight measuring device 13: Computer 14: Controller 15: Air injection port (slit-shaped injection port) 16: Individually independent air injection port (air injection nozzle) 17: Adjusting valve 18: Air injection device 19: Main valve, pressure reducing valve, etc.

Claims (5)

[Claims] 1. A high-speed airflow traction device for drawing and narrowing a continuous filament group obtained by melt-spinning a thermoplastic resin from a spinneret, and the IDT conveyed with the airflow from the high-speed airflow traction device. The continuous filament group of
In a method for producing a spunbonded nonwoven fabric which is guided to a corona discharge unit composed of a corona discharge electrode and a plate-like target electrode and spreads, the filament is disposed at a position on the corona discharge electrode side downstream of the corona discharge electrode, over the entire width of the filament group in the width direction. An air injection device having an air injection port provided, and a number of adjustment valves capable of partially adjusting the amount of air in the air injection port in the width direction are provided. Spunbonded nonwoven fabric characterized in that the fiber is opened by passing through a corona discharge electric field while being pressed against the fabric, and the basis weight of the nonwoven fabric is adjusted by partially adjusting the amount of air in the width direction of the device with an adjusting valve. Method. 2. An air injection device according to claim 1, wherein the air injection device has a large number of individually independent air injection ports disposed at a position downstream of the corona discharge electrode and on the corona discharge electrode side over the entire width in the width direction of the filament group. Manufacturing a spunbonded nonwoven fabric, comprising: providing a large number of adjusting valves capable of individually adjusting the air amount of the air injection port, and further including an air injection device having a slit-shaped air injection port continuous over the entire width in the width direction. Method. 3. The apparatus according to claim 1, further comprising an apparatus capable of continuously measuring a basis weight of the nonwoven fabric in a width direction.
A method for producing a spunbonded nonwoven fabric, wherein the basis weight of the nonwoven fabric is adjusted by adjusting the adjustment valve in conjunction with a signal from the apparatus. 4. A continuous filament group obtained by melt-spinning a thermoplastic resin from a spinneret and drawing by means of a high-speed airflow traction device to be drawn and thinned. The continuous filament group of
In a manufacturing apparatus for a spunbonded nonwoven fabric, which is guided to a corona discharge unit composed of a corona discharge electrode and a plate-like target electrode and spreads the fiber, at a position on the corona discharge electrode side downstream of the corona discharge electrode, the filament is arranged over the entire width in the width direction of the filament group. An air injection device having an air injection port provided, and an adjustment valve capable of partially adjusting the air amount of the air injection port in the width direction are provided, and the continuous filament group is pressed against the flat target electrode by the injection air. A filament group opening apparatus characterized in that the fiber group is opened by passing through a corona discharge electric field while opening, and the amount of air is partially adjusted in the width direction of the apparatus by an adjustment valve. 5. An air injection device according to claim 4, wherein the air injection device is provided at a position downstream of the corona discharge electrode and on the side of the corona discharge electrode, over the entire width of the filament group in the width direction, and having a large number of individually independent air injection ports. A plurality of adjusting valves capable of individually adjusting the amount of air in the air injection port, and an air injection device having a slit-shaped air injection port continuous over the entire width in the width direction is provided. apparatus.