JPS59187659A - Web widening method - 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 widening a web. More specifically, this is a method for uniformly widening the web when producing long-fiber nonwoven fabrics made of thermoplastic polymers, and uses a secondary flow to uniformly widen the web to be deposited on a net conveyor of yarn taken up by an air sucker. This relates to a method of widening the width.

Conventionally, a method is known in which a thermoplastic polymer is melt-spun and then pulled, thinned, and opened using an air sucker to form a web consisting of long fibers.

This method is generally called the spunbond method, and has the advantage that a cloth-like article can be obtained directly from the thermoplastic polymer without knitting or weaving it. Polyester, polyamide, and polypropylene have already been commercialized as thermoplastic polymers. A representative patent related to the spunbond method is
Japanese Patent No. 4993 is known, in which a multi-filament yarn is forcibly charged by being towed at high speed by an air sucker and electrostatically applied at a position before the entrance of the air sucker, and then opened.

When air suckers are used as the pulling and opening means, it is generally necessary to line up a large number of air suckers in the width direction of the web. Interference occurs between the ejected airflows, creating thinner areas between the air suckers (usually called joints).

Therefore, in order to reduce the cost, the air suckers are not arranged in a row in the width direction, but are staggered in the diagonal direction, so that the pile of yarn ejected from one air sucker forms a certain shape in the width direction of the nonwoven fabric. A method is disclosed. In this method, the yarns ejected from several air suckers are stacked and deposited in the width direction of the nonwoven fabric, so the joints in the nonwoven fabric are not noticeable. The problem is the spread width of the web. In other words, if the single fiber spreadability of the web is poor, no matter how many layers are laminated, the apparent quality of the nonwoven fabric will be significantly impaired, and if the web has a narrow spreading width, a large number of air suckers must be arranged in the width direction. be.

Many techniques have been disclosed in the past regarding web widening methods. Various width widening techniques are known, including those using mechanical rocking, those using reflection from a collision plate, and those using air flow. For example, in Japanese Patent Publication No. 46-34373, the aim is to widen the web by colliding the yarn coming out of an air sucker with a collision plate and injecting pressurized air from behind the collision plate, but the width widening effect is small.

Conversely, if the collision plate is a flat plate, increasing the pressure may cause the web width to become narrower.

In addition, in Japanese Patent Publication No. 57-48657, the yarn coming out of the air sucker is made to collide with a collision plate, and pressurized air is injected to the yarn traveling near the collision plate, and a deflecting member is provided on the exit side of the collision plate. The purpose is to widen the web by vibrating it at high speed. However, such a method of vibrating the deflecting member on the exit side of the collision plate at high speed is mechanically complicated, and macroscopic unevenness is likely to occur due to uneven distribution of the web due to vibration. Moreover, if the pressure air flow is simply applied without high-speed vibration, only a slight widening effect can be seen.

The present inventor completed the present invention as a result of intensive research into a method for widening the web that does not cause macroscopic spots and has good single fiber opening properties.

That is, in the present invention, when the yarn forcibly charged by corona discharge collides with multiple stages of collision plates Km and falls and accumulates in the direction of the net conveyor while changing the traveling direction, the yarn travels near the collision plate of the final stage. A method for widening a web characterized by applying a secondary flow to the yarn to widen it. The present invention will be explained in detail below.

The present invention has no mechanically moving parts and uses a forced charging method using corona discharge and a method of using a plurality of collision plates and applying a secondary air flow to the final collision plate, thereby achieving uniform charging. Moreover, it provides a method that can sufficiently widen the web width.

Thermoplastic polymers according to the present invention include general polyethylene terephthalate, polybutylene terephthalate, copolymerized esters containing isophthalic acid, adipic acid, etc., nylon 6.66.610, or copolymerized or blended polyamides containing a third component. In general, any material that can be melt-spun may be used, such as polyolefins such as polyethylene, tactical polypropylene, etc.

It goes without saying that the polymer may contain a matting agent, a heat stabilizer, a coloring agent for the purpose of dyeing, etc. Naturally, it may also be a sheath-core fiber, a laminated fiber, a composite fiber with a sea-island structure, or a mixed fiber yarn.

The present invention can be applied to a yarn traction system using a normal air sucker. As an air soccer, a regular round air soccer is preferable because it can be towed at high speed. Naturally, between the spinneret and the air sucker there is a high-speed rotating roll (3000 ~
(1000 m/min), the fibers are taken up with rolls, and then opened with an air sucker. It is necessary to apply an electrostatic charge to the spun yarn by forcibly charging it with corona discharge before entering the air sucker or after leaving the air sucker. An example of an embodiment of the web widening method according to the present invention is shown in FIG. 1st
In the figure, when the yarn 2 leaving the air sucker 1 passes through the corona discharge channel 3, it is forcibly charged by corona discharge between the needle electrode &4 and the target electrode &5. The yarn exiting the corona discharge channel 3 is caused to collide with a plurality of collision plates. FIG. 1 shows the case of two collision plates. First collision plate 6
, collide with the second collision plate 7 one after another, and then deposit on a net conveyor (not shown). The accumulated web is static-eliminated using an AC static eliminator or a DC/φ AC static eliminator (not shown) in the same manner as in the usual manufacturing method, and then thermally pressed with an embossing roll and then wound up with a winder. The nonwoven fabric according to the present invention may be bonded by a thermocompression bonding method using an embossing roll, a needle punching method, or a resin processing method.

The key point of the present invention is that, unlike the conventional method of mechanically changing the destination of the yarn by vibration, rocking, rotation, etc. to widen the web, the key points of the present invention are a forced charging method using corona discharge, multiple collision plates, and the final The key point is to combine the method of causing the collision plate to act on the secondary pressure air flow. The corona discharge device used here is the needle electrode 4.
and a target 5, and a high DC voltage (usually 10 to 40 KV) is applied between them to cause a corona discharge. Corona discharge electrodes can be used in one or more stages in the running direction of the yarn. As the yarn speed increases, the amount of charge on the yarn tends to decrease, especially when the yarn running speed is 5,000 yen.
If the discharge time exceeds 0 m1 minute, it is preferable to use multiple stages of corona discharge devices, particularly two stages stacked one on top of the other. The yarn leaving the corona discharge electrode is made to collide with the first collision plate 6.

At this time, the angle between the collision plate 6 and the yarn traveling direction is 20~
45°, particularly around 35°, is preferable since macroscopic spots do not occur.

The yarn that has left the collision plate collides with the second collision plate 7 that is 2 to 5 u away, and deflects the running direction toward the net conveyor.

In FIG. 1, the second collision plate 7 is the final collision plate, and it is preferable for this final collision plate to be used in a direction perpendicular to the net conveyor, that is, to deposit yarns almost vertically on the net conveyor to avoid macroscopic spots. . By applying a secondary flow from the air nozzle 8 to the yarn traveling in the vicinity of the final collision plate 7, the effect of widening the width of the sieve is significantly increased. The air nozzle used at this time may be of a round hole or slit type, but it is particularly preferable to eject air from a round hole nozzle of 2 to 5 vn and blow it toward the collision plate.

By applying a secondary flow to the yarn running near the vertical plate, the thread expands in the width direction while falling almost vertically, and due to the electrostatic charge that is generated near the net conveyor where the influence of the accompanying flow is less It is thought that the single filament spreadability is improved. Even if a secondary flow is applied to the yarn running on the reflector under similar conditions, a similar widening effect can be seen, but as shown in the example, there is a clear difference in the widening width of the web. It is preferable to cause a secondary flow to act on the yarn running nearby. Further, the number of filaments that can be opened can be as small as possible, but especially if it is about 50 to 500 filaments, the width can be expanded without any problem.

Rather than using a method in which a secondary flow, that is, a second gas flow is applied to the yarn that collides with and runs on one stage of collision plates, the present invention uses a plurality of stages of collision plates and runs near the final stage of collision plates. The reason why the method of applying the second gas flow to the yarn is superior has not yet been completely clarified, but one reason is that the yarn leaving the final collision plate 7 is almost perpendicular to the net conveyor. In addition, the accompaniment pressure air flow from the air sucker is diffused by colliding with the first collision plate.
This is thought to be because the flow is rectified by running between the first collision plate and the second (final in FIG. 1) collision plate, making it difficult for macroscopic spots to occur when the web is deposited. As a method for producing a wide nonwoven fabric, for example, by using air suckers in a staggered arrangement and setting the lamination rate of the web to 30 to 75 inches, a nonwoven fabric that is free from knots and has good leather thread opening properties can be obtained.

Further, the deposition distribution of the Ugobu according to the present invention is as shown in FIG. 2 (Example 2), for example, when two stages of collision plates are used and no secondary pressure air flow is used (Comparative Example B), the width of the raised central part is It is narrow. On the other hand, when a secondary pressure air flow is applied to the 16th collision plate, the deposition distribution becomes wider as in Comparative Example E, but at this stage macroscopic spots are already visible in some areas.
The dispersion is never clean. On the other hand, in the case of Example A according to the present invention, there is no bulge in the central part and the deposition distribution is almost flat. Moreover, with this method, the first
Unlike the case where the second pressure air flow is applied to the collision plate, it is also possible to arbitrarily change the deposition distribution from Comparative Example B to Example A to some extent by finely adjusting the position and pressure of the pressure air flow. . In this case, macroscopic spots do not occur even when the second pressure air flow is applied, and a nonwoven fabric with good dispersion can be obtained. however,
If this second pressure airflow is too thick, the central part may become concave in the deposition distribution, which may be undesirable. The web deposition distribution referred to here was calculated by cutting the web by 10 m in the direction of travel, cutting it into pieces in the width direction in units of ltM, measuring the weight of the web with an area of IXIOm, and converting it into a basis weight (f/: unit) K. It is something.

The nonwoven fabric according to the present invention can be used for civil engineering materials and
Roof ink materials, agricultural materials, bag materials using polyamide, diaper top sheets using polypropylene,
Can be used as tea bags, etc.

The present invention will be explained in detail below.

Example 1 A thermoplastic polymer, non-chemically formed M1300 (melt flow rate) = 4.0), was added as a molecular weight reducing agent.
Using polypropylene mixed with 200 ppm of n-butyltin male, 0.40. Spinning was carried out at 300°C using four spindles with $X6B holes. 10th rule is 1500
@/minute, @20-le is 3. Stretching was carried out with a Gotet roll consisting of two pairs of Nelson rolls rotated at 00 m/min. At this time, the discharge amount was set so that the single filament denier was 1.5 denier. A single stage corona discharge device was used and a current of 0.25 mA was applied to open the fibers. Using a copper reflector as an air nozzle, set a 3U round hole nozzle 4 ports away from the vertical plate to produce 0.5 Ky/l.
A pressure of ri G was applied to create a secondary flow. Air soccer consisted of 200 birds and 4 pitches. By using the secondary flow, the web width of one spindle was expanded to about 45 ON (distance to the lower end of the vertical plate of the net conveyor = 400 tnyn), and a nonwoven fabric without myositis was obtained by lamination.

Without the use of secondary flow, the web width of one spindle was only about 200 u, and myositis was observed between the air suckers.

Example 2 Polyethylene terephthalate (intrinsic viscosity = 0.68) was extruded with one spindle at a discharge rate of 461 y/min using a spindle of 0.40 m/×83 holes. At this time the 10th-
5. Do not use the 20th rule. 0 picked up at ooom/min
An intermediate air sucker was installed at a position 2 m below the spinneret, and an air sucker for opening was placed at a position of 100*a directly below the 20th loop for stable spinning, and the yarn was pulled with a pressure of 4.5 K9/iG. . Two stages of corona discharge electrodes were used, and the distance between the electrodes and the target electrode was adjusted by M1 so that o and a mA flowed through separate power supplies. Table 1 shows the results when the angle θ of the reflector was set to 35'', and it was found that the example of the present invention was superior in terms of web width and single yarn opening property, and especially when implemented. As shown in FIG. 2, in Example A, the deposition distribution is flat and the web deposition width is larger than in the comparative example.

Example 3 85056 manufactured by Chisso Corporation was used as the thermoplastic polymer.
Extrude 4 spindles of o23φX120 holes at a total discharge rate of 400 r/min No. 10 - 2000? ? ! /min No. 20-5
．． 00077 After cold drawing for 17 minutes, the air sucker pressure of one yarn was taken at 4-5 Kg/l: r/i G. 1. Using a round hole air nozzle. Org7
Air was blown out with tatta. At this time, the web width was increased to about 450 mm), but a nonuniform nonwoven nib was obtained, although the edges were slightly thinner.

It was possible to heat-press the fabric to a textured embossing roll with a surface temperature of 146°0 at a temperature of 7'C, and the obtained nonwoven fabric had no macroscopic spots.
g73 cm width.

Elongation 48 inches, width 6J Kg/3 crn width, elongation 45
It showed.

[Brief explanation of drawings]

FIG. 1 shows a perspective view of a web widening device according to the invention. Technique: Exit part of air sucker, 2: Thread exiting air soccer, 3: Corona discharge channel, -4: Needle electrode,
5: target electrode, 6: first collision plate, 7: final collision plate, 8: second pressure air flow blowing nozzle. FIG. 2 shows the web deposition distribution in Example 2. Patent applicant: Asahi Kasei Industries, Ltd. 15- Figure 1

Claims (1)

[Claims] When yarn forcibly charged by corona discharge collides with multiple stages of collision plates and is dropped and deposited in the direction of the net conveyor while changing its direction of travel, secondary damage occurs to the yarn running near the collision plate of the last stage. A method for widening a web characterized by widening it by applying a flow