JPH07268753A - Production of web for broad nonwoven fabric - Google Patents

Abstract

PURPOSE:To produce a nonwoven fabric having uniform areal weight distribution by subjecting a melt-spun filament group to static opening by corona discharge treatment, depositing the filaments on a conveyor and destaticizing the deposited web. CONSTITUTION:This nonwoven fabric 15 having uniform thickness is produced by extruding a molten polypropylene through a spinneret 1 having circular nozzles, drawing the obtained continuous filament group 2 through an air sucker 4, guiding to a slit 5 having a width of 0.7-1.3d (d is the inner diameter of the outlet of the nozzle of the air sucker 4) to form a flat filament group, applying static charge to the filament group 2 by corona discharge treatment between a needle electrode 6 and a target electrode 7, depositing the opened filaments through an inclined collision plate 8 on a moving net conveyor 11 to form a web 10, destaticizing with a destaticizer 13 and hot-pressing with an embossing roller 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a web for a non-woven fabric, which is suitable for a lining of clothes, a roofing material, a bag material, a civil engineering material and the like.

[0002]

2. Description of the Related Art A continuous fiber group obtained by melt-spinning a thermoplastic resin from a spinneret is introduced into a nozzle of a suction carrying-out device (air sucker), pulled, thinned and opened, and collided with a collision plate. After that, it is generally known as a spunbond method to put a web for a non-woven fabric on a running conveyor belt (Japanese Patent Publication No. 37-4993).
No. 46-34373, No. 57-48657 and Japanese Patent Publication No. 5-24261).

For example, Japanese Patent Publication No. 37-4993 discloses that
A method for producing a nonwoven fabric web by charging the melt-spun filaments, separating the filaments, guiding the filaments to a suction carry-out device, and then receiving the filaments on a conveyor belt equipped with a neutralization device is disclosed. According to this method, interference occurs between the air streams of the fluid ejected from the suction carrying-out device, and a portion with a small basis weight (so-called streak) occurs on the web.

Japanese Patent Publication No. 46-343373 discloses that a group (bundle) of continuous fibers is caused to collide with a collision plate together with a high-speed fluid, and an auxiliary jet flow is ejected from behind a position where the high-speed fluid collides with the collision plate. Disclosed is a method for producing a widened web for nonwoven fabric with sufficient opening. Also, Japanese Examined Japanese Patent Publication No.57-4
No. 8657 discloses 100 to 60,000 times as a collision plate /
Of the non-woven web for expanding the width of the filament group by 5 to 30% by discharging the pressurized fluid in the lateral direction to the portion where the filament group of the diagonal collision plate collides. A method is disclosed.

In the web manufacturing methods using these high-speed fluids, the widening is not sufficient, and the weight of the web changes, and macroscopic unevenness easily occurs. Japanese Examined Patent Publication No. 5-24261 discloses a group of filaments melt-spun by using the charging described in Japanese Patent Publication No. 37-4993, the oblique collision plate described in Japanese Patent Publication No. 57-48657, and a pressure fluid sprayed on the plate. Guided to a suction carry-out device, then corona discharge treatment forcibly charged filament groups collide with a plurality of stages of collision plates to drop in the direction of the net conveyor while changing the traveling direction, when depositing the web on the net conveyor, The secondary pressure airflow is applied from a nozzle having a cross-sectional area of 3 to 20 mm ² at the downstream of the point where the filament collides with the charged filament running along the collision plate at the final stage of the collision plate. We propose a web widening method characterized by widening the filaments. This method is an effective means for expanding the width of the web, but it is not sufficient because the deviation of the basis weight with respect to the width of the obtained web is still large.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a web for a non-woven fabric, which is easy to widen and has a uniform basis weight distribution with respect to width changes.

[0007]

According to the present invention, a continuous fiber group of filaments melt-spun from a spinneret is guided to a nozzle of a suction carrying-out device, and then this continuous fiber group is formed by a pair of plates. With respect to the outlet diameter d of the nozzle of the suction carrying-out device, the lateral width of the group of continuous fibers is expanded by passing between slits having a width of 0.7d to 1.3d, and the lateral fiber is expanded into the group of continuous fibers. Provided is a method for producing a wide nonwoven fabric web, which comprises corona-discharging and electrifying, colliding a group of electrified continuous fibers with a collision plate to widen it, placing it on a running conveyor belt, and removing the electricity. To do.

Manufacturing Apparatus An apparatus used for manufacturing the web of the present invention is shown in FIG.
In FIG. 1, 1 is a spinneret (die) having a large number of discharge holes, 2 is melt spinning, 3 is an air cooling device, 4 is a suction unloading device (air sucker), 5 and 5 are flat plates, 5'is a slit,
6 is a needle electrode, 7 is a target electrode, and 6 and 7 form a corona discharge device. 8 is the inclination (α = 5 to 20 degrees)
A collision plate, 9 is a group of charged filaments, 10 is a web, 11 is a net conveyor belt, 12 is a fluid (air) suction device, 13 is a static eliminator, 14 is a heated embossing roll, and 15 is a nonwoven fabric.

FIG. 2 is a sectional view of the air-cooling device 3 taken along the line I-I.
a is a cavity, 3b is a gas (cooling air) blowout hole provided in the inner cylinder, 3c is a gas supply pipe, and 3d is a cold air generator. FIG. 3 is a plan view of the flat plates 5 and 5 forming the slit, 5a is a slit, and 2,2, ... Are groups of continuous fibers whose width is expanded in a lateral direction in a substantially elliptical shape.

[0010]

The molten thermoplastic resin is extruded through a large number of discharge holes of the spinneret 1 having a circular cross section to form a group (bundle) of continuous fibers 2 of filaments. This group of fibers is
It shows a circular distribution in the lateral direction.
Is forcedly cooled by the cooling air of 10 to 25 ° C. blown out from the air cooling device 3 in a direction (lateral direction) perpendicular to the traveling direction of the filament (the temperature of the filament is 50 ° C. or higher than the melting point of the raw material resin of the filament). Low temperature).

Next, the group of filaments is guided into the cylindrical nozzle of the suction and unloading device 4, and after passing through this,
The lateral width of the filament group 2 is expanded by passing the slits formed by the flat plates 5 and 5 into contact with each other. The filament groups 2, 2 ... The width of which is widened are forcibly charged by corona discharge between the needle electrode 6 and the target electrode 7. The charged filament group 9 collides with the collision plate 8 and the net conveyor 1
A web 10 is deposited on top of 1. The accumulated web 10 is discharged by the AC / DC static eliminator 13 and then the embossing roll 14
Then, the nonwoven fabric 15 is thermocompressed with and wound up.

As the thermoplastic resin for the material of the thermoplastic resin filament (fiber),
Copolymerized esters containing polyethylene terephthalate, polybutylene terephthalate, isophthalic acid, adipic acid, etc., nylon 6,66,610 or copolymerized or blended polyamides containing a third component,
Any melt-spinnable material such as polyolefin such as polyethylene and isotactic polypropylene can be used. Of course, the resin may contain a matting agent, a heat stabilizer, or a coloring agent for the purpose of primary coating. Further, of course, it may be a composite fiber or a mixed fiber having a core-sheath structure or a laminated body of a laminated structure, a sea-island structure or the like.

Air Cooling Device The air cooling device 3 has the structure shown in FIG. The blown wind speed is 0.2 to 2 m / sec. By this forced cooling, the filament take-up speed can be increased.

Suction carry-out device (air sucker) As the suction carry-out device 4, a round air sucker is usually used.

Slit The jig for forming the slit is composed of a pair of flat plates 5 and 5 as shown in FIG. The width of the slit 5a is 0.7d to 1.3 which is the diameter d of the outlet of the cylindrical nozzle of the air sucker 4.
It is set to be d. Thus, the slit gap 5a differs depending on the outlet diameter of the cylindrical nozzle of the air sucker and the spinning speed. For example, when the outlet diameter of the air sucker nozzle is 12 mmφ, the slit gap should be 15 to 10 mm.
mm, preferably 11 mm. If it exceeds 15 mm, the widening is small and the central part of the obtained nonwoven web becomes thick. On the other hand, if the width is less than 10 mm, the widening effect can be seen, but the central portion becomes thin. Further, the filament is caught in the slit jig, which causes a trouble.

Further, when the spinning speed is 3,000 m / min, the slit gap is 13 mm, whereas the spinning speed is 5,000.
10 mm is preferable at m / min. When the spinning speed is increased, the accompanying flow of the fluid (air) increases, and if it is not flattened, the widening effect cannot be obtained.

Corona Discharge Device The corona discharge device is composed of a needle electrode 6 and a target electrode 7, and a high direct current (usually 10 to 40 kV) between them.
To discharge the corona. At that time, the target electrode 7 is preferably a rotating roll type rather than a fixed type.

Collision plate The collision plate 8 is preferably inclined as shown in FIG. 1 so that the angle (α) formed by the collision plate 8 and the traveling direction of the filament is 5 to 20 °. Particularly, about 10 ° is preferable. If it is less than 5 °, the widening effect is small and the uniformity of the web is poor. On the other hand, when the angle exceeds 20 °, the air is sucked toward the net conveyor 11 so that the suctioned air flow generated by the air suction device 12 is generated almost at right angles to the net conveyor 11, so that the yarn sheath is slanted and easily disturbed, resulting in unevenness. It will be a web with a natural weight. On the other hand, the number of filaments that can be opened may be small, but there is no problem within the range of 30 to 300 filaments and the width can be expanded.

Nonwoven Fabric The nonwoven fabric according to the present invention can be obtained by integrating the web by a thermocompression method using an embossing roll, a needle punching method, or a joining method by resin processing.

[0020]

【Example】

Example 1 A nonwoven fabric was manufactured using the manufacturing apparatus shown in FIG. That is,
Using polypropylene (MFR 50g / 10min), 4
It was extruded from a single spinneret having a circular cross-section of 200 mmφ having 200 mmφ small holes at a discharge rate of 200 g / min.

An air sucker (nozzle outlet diameter: 12 mmφ) was installed at a position 1.5 m below the spinneret and was set at 6.0.
At a pressure of kg / cm ² G, filament speed 4500 m /
Towed in minutes. Immediately after flattening the filament group with a jig having a slit gap of 11 mm, corona discharge 0.3 m
The current of A is flown to open the fiber, and it collides with a collision plate inclined at 15 degrees to widen it, guides it onto a rotating net conveyor belt (30 m / min) to form a web, and then eliminates electricity. By thermocompression bonding with an embossing roll at 145 ° C., a nonwoven fabric having a fineness of 2.0 denier and a width of 400 mm was obtained.

Single yarn (filament) openability of this product,
Table 1 shows the uniformity of basis weight (thickness distribution in the width direction). or,
The nonwoven fabric is cut into 2 cm units in the width direction, the weight of the nonwoven fabric having an area of 10 cm in length and 2 cm in width is measured, and the weight is measured (g
/ M ² ) and shown in FIG.

Evaluation Criteria for Single Thread Opening A : No bundle of filaments in each other X: Many bundles of filaments in each other

Comparative Example 1 A nonwoven fabric having a width of 200 mm was obtained in the same manner as in Example 1 except that the slit jig was not used.

Comparative Example 2 A nonwoven fabric having a width of 400 mm was obtained in the same manner as in Example 1, except that the corona discharge treatment was not performed.

Example 2 In Example 1, the slit interval 11 mm was changed to 14 mm.
A nonwoven fabric having a width of 380 mm was obtained in the same manner except that

Example 3 A nonwoven fabric having a width of 350 mm was obtained in the same manner as in Example 1 except that the angle of the collision plate was changed from 15 ° to 10 °. Table 1 shows the openability of the single yarns of these non-woven fabrics and the thickness uniformity of the non-woven fabrics. Further, FIG. 4 shows the distribution of the basis weight in the width direction of the nonwoven fabrics obtained in Comparative Examples 1 and 2.

[0028]

[Table 1]

[0029]

EFFECT OF THE INVENTION It is possible to manufacture a non-woven fabric having a wide distribution of wall thickness (area weight).

[Brief description of drawings]

FIG. 1 is a perspective view of a nonwoven fabric manufacturing apparatus.

FIG. 2 is a cross-sectional view taken along the line II of the air cooling device.

FIG. 3 is a plan view of a slit.

FIG. 4 is a diagram showing a distribution of a basis weight of a nonwoven fabric in the width direction.

[Explanation of symbols]

 1 Spinneret 2 Filament 3 Air-cooling device 4 Air sucker 5 Slit jig 6 Needle electrode 7 Target electrode 8 Collision plate 10 Web 15 Nonwoven fabric

Claims (2)

[Claims] 1. A continuous fiber group of filaments melt-spun from a spinneret having a circular cross section is guided to a nozzle of a suction discharge device, and then this continuous fiber group is formed by a pair of plates. For the outlet inner diameter d of the nozzle of the device,
The lateral width of a group of continuous fibers is expanded by passing through slits having a width of 0.7d to 1.3d, and the group of continuous fibers whose lateral width has been expanded is corona discharge treated to be charged, and the charged continuous fibers are charged. A method for manufacturing a wide web for nonwoven fabric, characterized in that the group of (1) is collided with a collision plate to be widened, and this is placed on a running conveyor belt to eliminate static electricity. 2. A continuous fiber group of filaments melt-spun from a spinneret is forcibly cooled by cooling air blown perpendicularly from an air-cooling device with respect to the traveling direction of the continuous fiber group, and then to a suction unloading device. The manufacturing method according to claim 1, wherein the manufacturing method is guided.