JPH08109565A - Production of spunbonded nonwoven fabric - Google Patents

Abstract

PURPOSE: To obtain a spunbonded nonwoven fabric low in METSUKE (2-200g/m<2> , a weight unit) unevenness, uniform in METSUKE distribution, and having good formation. CONSTITUTION: A thermoplastic resin is subjected to melt spinning in screen- fashion from a spinneret 1 into continuous long fibers 2, which are then drafted by a high-speed air jet drafting device 3 with rectangular cross section to effect drawing; the resultant drawn long fibers are made to impinge on an opening reflection plate 4 and accumulated on a net conveyer 7 to obtain a nonwoven web 8 that is the objective spunbonded nonwoven fabric. In this process, the continuous long fibers are passed through between a pair of nearly parallel plates constituting a device 5 to trim the high-speed air jet situated under the reflective plate, thereby suppressing the diffusion of the long fibers toward the advancing direction of the net conveyer and guiding and accumulating them onto the net conveyer without stalling them.

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 non-woven fabric composed of long fibers of thermoplastic resin. More specifically, the present invention relates to a method for producing a spunbond long-fiber non-woven fabric having a small basis weight, a uniform basis weight distribution and a good texture.

[0002]

2. Description of the Related Art The spunbond method is one of the methods for obtaining a nonwoven fabric from a continuous filament group formed by spinning a thermoplastic resin. In the spunbond method, a thermoplastic resin is melt-spun to form a continuous long fiber group, and the continuous long fiber group is thinned and drawn using a high-speed air flow traction device. In recent years, demand is increasing as a method of forming a nonwoven web by depositing it on a conveyor to obtain a nonwoven fabric at low cost with high productivity. What is important here is to uniformly disperse the continuous long fiber group that has exited from the high-speed airflow traction device, and the uniform dispersion of the continuous long fiber group leads to improvement of the quality of the nonwoven fabric.

Various proposals have been made in the past as a method for uniformly dispersing continuous continuous fibers, but continuous fiber groups ejected from a high-speed airflow traction device are collided with a reflecting plate to be triboelectrically charged. Alternatively, a method is known in which an appropriate electric charge is applied to the continuous fiber group by performing corona discharge toward the continuous long fiber group, and the continuous fiber group is dispersed by its repulsive force. However, with these methods, although the dispersion of the individual fibers when viewed locally is good, it is difficult to suppress the unevenness of the thickness, that is, the unevenness of the weight when viewed as the whole nonwoven fabric.

[0006] The eye spot is caused by the following events. The continuous fibers ejected from the high-speed airflow traction device can be dispersed evenly by the various fiber-spreading methods, but when traveling along with the airflow in the air until they are accumulated on the net conveyor provided in the injection direction. Stall due to air resistance, etc., causing irregular velocity distribution in the continuous continuous fiber group, attracting the adjacent continuous continuous fiber toward the continuous continuous fiber having a high speed, and forming a lump in the continuous continuous fiber group. After the spouting, since the diffusion width of the air flow increases as the continuous fiber group progresses after ejection, the fiber mass sways in the same direction as the traveling direction of the net conveyor and accumulates on the net conveyor at irregular intervals. The spotted spots are generated.

As a method of suppressing such a phenomenon and obtaining a nonwoven web having a uniform texture, many proposals have been made as follows. (A) A method of increasing the velocity of the jet airflow, that is, the pressure of the gas supplied to the high-speed airflow traction device. (B) A method of arranging a plurality of spinnerets vertically to the traveling direction of the net conveyor and stacking them to obtain a nonwoven web.

(C) A method in which an oscillating device is provided under the high-speed air flow traction device to oscillate the continuous filament group at a right angle to the traveling direction of the net conveyor or at a certain angle (Japanese Patent Laid-Open No. 49-49).
-85370). (D) A method in which a continuous dispersion of continuous filaments is redistributed by disposing an arc-shaped reflective dispersion plate below the high-speed airflow traction device to suppress the unevenness of the fabric (JP-A-61-47860). (E) Separate excess surplus high-speed airflow at the entrance part of the slit rectification device by using a slit rectification device with a narrow rectangular slit provided with a wall or collision plate for preventing continuous long fibers from popping out just below the high-speed airflow traction device A method of rearranging the continuous long fiber group (JP-A-57-143552).

The above methods (a) to (e) have advantages and disadvantages as described below, and are not always satisfactory. (A) The method of increasing the pressure of the gas supplied to the high-speed airflow traction device can easily prevent the stall of the continuous long fiber group, but increases the speed and air volume of the high-speed airflow that pulls the continuous long fiber group. Therefore, since the fiber flow is separated into the fiber and the air flow on the net conveyor, it is necessary to increase the suction wind speed of the suction device provided at the bottom of the net conveyor to deal with it, and the equipment cost and power cost for this are bulky and inexpensive. It is difficult to obtain a nonwoven fabric. (B) In the method of arranging a plurality of spinnerets perpendicularly to the traveling direction of the net conveyor, when the speed and the air volume of the air flow are increased, on the net conveyor which has been pre-deposited in the accumulating portion of the continuous long fiber group in the second and subsequent rows Is not preferable because it disturbs the fiber arrangement of the non-woven web.

(C) In the method using the oscillating device, for example, when the manufacturing speed is increased to improve productivity, the oscillating speed of the collision plate must be increased accordingly. The higher the manufacturing speed, the higher the collision plate. The oscillating device requires high precision and technology, and it is difficult to easily suppress the above-mentioned phenomenon. When the collision plate also serves as a reflecting plate for opening continuous continuous fiber groups, the collision plate is constantly displaced, so the amount of electric charge applied to the continuous continuous fiber group is constantly changing and the nonwoven web of a certain texture is formed. Is difficult to obtain continuously, which is not preferable. (D) In the method of using the reflecting plate curved in an arc shape, since the continuous filaments that are deeply hit and reflected on the arc surface of the reflecting plate and the continuous filaments that are shallowly hit and reflected have different velocities after reflection. There is a risk of promoting the generation of the aforementioned fiber lumps.

(E) In the method disclosed in Japanese Patent Application Laid-Open No. 57-143552, a so-called accompanying flow, which is drawn from the atmosphere portion to the high-speed airflow portion due to the pressure difference between the high-speed airflow portion and the atmosphere portion, is called a high-speed airflow traction. It also occurs between the device and the slit rectification device, so the amount of air at the entrance of the slit rectification device becomes larger than the amount of air when ejected from the high-speed air flow traction device, and this increased amount of high-speed air flow In order to separate and reduce the weight of the non-woven web at the entrance portion where the anti-pop-up wall or the collision plate is attached, it is difficult to set the angle of the non-protrusion wall or the collision plate, and It is necessary to control the surface smoothness and the surface shape with high accuracy. If these are not satisfied, the separated excess high-speed air flow interferes with the high-speed air flow ejected from the high-speed air flow traction device and disturbs the flow of the high-speed air flow on the main stream side, rather hindering the uniform dispersion of continuous long fiber groups. . Further, separating the high-speed airflow and reducing the amount thereof reduces the kinetic energy of them, so there is a risk that the continuous fiber group will stall before the continuous continuous fiber group reaches the net conveyor. Absent.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method capable of industrially obtaining a spunbonded nonwoven fabric with less unevenness of weight. is there. More specifically, the present invention provides a high-speed airflow rectifying device composed of a pair of substantially parallel plate-like objects that rectify the high-speed airflow ejected from the high-speed airflow traction device, thereby suppressing stall of the continuous long fiber group. At the same time, it is intended to obtain a spunbonded non-woven fabric having a good texture with a uniform basis weight distribution and a uniform basis weight distribution by suppressing the diffusion of the high-speed air stream.

[0011]

Means for Solving the Problems (1) According to the present invention,
A continuous long fiber obtained by melt-spinning a thermoplastic resin in the shape of a blind from a spinneret was drawn by a high-speed air flow pulling device with a rectangular cross section to be thinned and drawn, and then collided with a continuous long fiber opening reflection plate. In the process of obtaining a nonwoven web by depositing on a net conveyor, a pair of substantially parallel to each other, which is provided below the reflection plate for continuous continuous fiber opening, rectifies the high-speed air flow that pulls the continuous continuous fiber The continuous long fibers are not stalled by passing between the pair of plate-like objects of the straightening device made of a plate-like object, and the continuous long fibers are also guided on the net conveyor while suppressing the diffusion in the traveling direction of the net conveyor. Provided is a method for producing a spunbonded nonwoven fabric made of continuous long fibers, which is characterized by being deposited.

The method for producing the spunbonded nonwoven fabric of the present invention will be described with reference to the drawings. FIG. 1 is a view showing an example of an apparatus used for carrying out the spunbonded nonwoven fabric manufacturing method of the present invention. In FIG. 1, a spinneret 1 is a spinneret in which a plurality of rows of linearly arranged spinnerets are arranged.
The continuous long fiber group 2 melt-spun from the spinneret 1 becomes a blind and is guided to a high-speed airflow traction device 3 having a rectangular cross section,
While traveling between the spinneret 1 and the high-speed airflow traction device 3, it is thinned and stretched. The continuous long fiber group 6 ejected from the high speed airflow pulling device 3 together with the high speed airflow is collided with the continuous long fiber opening reflecting plate 4 provided below the high speed airflow pulling device 3 to be charged and uniformly opened. . Thereafter, the continuous long fiber group is guided onto the net conveyor 7 by a high-speed air flow to form a non-woven web 8.

The main point of the present invention is that, in the above-described process for producing a spunbonded nonwoven fabric, the continuous long fiber group which is opened by the reflecting plate 4 and is guided to the net conveyor 7 by the high-speed airflow is placed under the reflecting plate 4. It is to pass between the pair of plate-like objects of the rectifying device 5 composed of the pair of substantially parallel plate-like objects provided at the position. The high-speed airflow rectifying device 5 rectifies the high-speed airflow, and the continuous long fiber group is guided to the net conveyor 7 without stalling or diffusing.

[0014]

The principle of rectifying the high-speed air flow by the rectifying device 5 is as follows. First, FIG. 2 shows the flow of the high-speed airflow when the high-speed airflow rectifier 5 is not provided. The high-speed airflow 9 ejected from the high-speed airflow traction device 3 collides with the continuous long fiber opening reflecting plate 4, then flows along the reflecting plate 4, and is released and diffused at the end of the reflecting plate 4. Therefore, the continuous long fiber group accompanied by the high-speed airflow 9 also diffuses here. Since the continuous long fiber group is jetted into a large atmospheric space and diffused widely, it is easily affected by air resistance and stalls.

By the way, in order to minimize the diffusion and stall at the end of the continuous long fiber opening reflecting plate 4, the continuous long fiber opening reflecting plate 4 should be placed close to the net conveyor 8 and should be satisfactory. No results are obtained. That is, when the reflection plate 4 is moved downward from the high-speed airflow traction device 3 and brought closer to the net conveyor 8, the traveling distance of the high-speed airflow 9 between the high-speed airflow traction device 3 and the reflection plate 4 becomes long, so that diffusion occurs here. However, it is not preferable because it causes a stall and causes the occurrence of eye spots. The distance between the high-speed air flow traction device 3 and the continuous long fiber opening reflecting plate 4 is not changed, and the reflecting plate 4
If the end of the reflection plate 4 is made closer to the net conveyor 7 because the friction distance between the reflection plate 4 and the reflection plate 4 is increased, stall may occur here, causing undesired mottled spots. Furthermore, when the whole is brought close to the net conveyor 7 without changing the distance between the high-speed airflow traction device 3 and the continuous long fiber opening reflecting plate 4, stall and downward diffusion can be suppressed to some extent, but still upward. The diffusion remains as it is, which causes spotting. If they are brought too close to each other, a plurality of spinnerets 1 are arranged vertically with respect to the traveling direction of the net conveyor 7, and when the non-woven web 8 is obtained by laminating the fiber groups formed from the respective rows, the second and subsequent rows are provided. Net conveyor 7 that has been pre-deposited and has progressed in the deposition section of the continuous continuous fiber group of
It is not preferable because it disturbs the fiber arrangement of the upper nonwoven web and deteriorates the formation.

Next, FIG. 3 shows the flow of the high-speed air flow when the high-speed air flow rectifying device 5 is installed according to the method of the present invention. The high-speed airflow 9 ejected from the high-speed airflow traction device 3, which is opened at the end of the continuous long fiber opening reflecting plate 4, is limited in diffusion by the high-speed airflow rectifying device 5 located below it. In addition, since it is jetted into the narrow space between the pair of plate-shaped objects of the high-speed airflow rectifying device 5 and there is no diffusion, it is less susceptible to the influence of air resistance, and therefore stall can be prevented.

[0017]

Means for Solving the Problem (2) When the high-speed airflow straightening device 5 is not provided, the continuous long fiber opening reflection plate 4 is provided.
The continuous long fiber group ejected further spreads laterally as it approaches the net conveyor 7. Therefore, the lateral expansion of the continuous filament group must be adjusted according to the required product width. In the lateral direction, the flight distance from the continuous long fiber opening reflecting plate 4 to the net conveyor 7 should be shortened, that is, the angle of the reflecting plate 4 should be adjusted in a direction perpendicular to the net conveyor 7. It can be suppressed. However, a certain angle range must be maintained in order to provide the amount of charge necessary for the continuous continuous fiber group to open, and the adjustment range is a very narrow range. Further, changing the angle of the reflection plate 4 changes the charge amount distribution of the continuous long fiber group, and there is a risk of disturbing uniform opening.

In contrast to the above, when the high-speed airflow rectifying device 5 is provided according to the present invention, the direction of the high-speed airflow can be changed by changing the angle of the device 5, so that the continuous long fiber opening device is opened. It is possible to adjust the flight distance of the continuous long fiber group, that is, the spread width in the lateral direction without changing the angle of the fiber reflection plate 4, that is, without changing the charge amount distribution of the continuous long fiber group. The reflection plate 4 can also adjust its range.
Bigger than when done alone.

By the way, it is preferable that the distance between the pair of plate-like objects of the high-speed airflow rectifier 5 is 15 mm to 50 mm. This interval is 1
If it is smaller than 5 mm, the high-speed airflow cannot be sufficiently taken into the space between the high-speed airflow rectifiers 5, and the flow of the high-speed airflow is disturbed, and thus the continuous long fibers uniformly spread by the reflection plate 4 for continuous long-fiber opening. This is not preferable because it disturbs the group distribution. Further, if the interval is larger than 50 mm, the rectifying effect is weakened and both diffusion and stall occur, which is not preferable.

The length of the high-speed airflow straightening device 5 (length in the running direction of the fiber group) is preferably 40 mm or more, more preferably 50 mm or more. If this length is too small, the rectifying effect hardly appears, and it is difficult to suppress diffusion and stall. The upper limit of the length is not particularly limited as long as the distance between the end of the device 5 and the net conveyor 7 can be maintained at 200 mm or more in the vertical direction with respect to the net conveyor 7. However, even if the length of the device 5 is made larger than 300 mm, the effect does not change so much. On the contrary, if it is made too long, it is necessary to reinforce the device 5 in order to support it. Becomes difficult to install. Further, the distance between the end of the device 5 and the net conveyor 7 is 200
The end of the device 5 is made smaller than mm and the net conveyor 7
When a plurality of spinnerets 1 are arranged vertically to the traveling direction of the net conveyor 7 when they are brought close to the surface, and a fiber group formed from each row is laminated to obtain a nonwoven web 8.
It is not preferable because it disturbs the fiber arrangement of the non-woven web on the net conveyor 7 which has been pre-deposited and progressed in the deposition portion of the continuous fiber group after the row and deteriorates the formation.

The lateral length of the high-speed airflow straightening device 5 (the length in the direction orthogonal to the running direction of the fiber group) may be the same as that of the continuous-length fiber opening reflection plate 4. Obviously, if the length is shorter than this, the rectifying effect is lost, and the length need not be longer than this. The pair of plate-shaped objects of the high-speed airflow rectifier 5 are arranged substantially parallel to each other. If the arrangement of the devices 5 is not parallel but widened on the distal side, high velocity air flow
It is not preferable because it diffuses toward the end of and the rectifying effect disappears. Further, in the case where the end side is narrowed, the high-speed airflow is compressed at the end part, and therefore there is a risk that the high-speed airflow will spread widely when ejected from the end, which is not preferable. The material of the plate-like material that constitutes the high-speed airflow rectifier 5 is not particularly limited, and metals such as aluminum and stainless steel, wood, plastic, thick paper, and the like can be used. However, since the angle adjustment and the like require fine adjustment, a lightweight object is preferable.

[0022]

EXAMPLES The spunbonded nonwoven fabric manufacturing method of the present invention will be specifically described below. Example Using the apparatus shown in FIGS. 1 and 3, polypropylene having an MFR (melt flow rate) of 50 was melted at a melting temperature of 230 ° C. to form a rectangular spinneret (3500 spinning holes, 10 rows).
Rows, one row having 350 holes, one row having a length of 2000 mm and a hole diameter of 0.6 mm) were melt-spun at a discharge rate of 1 g per minute per hole, and the continuous long fiber group was arranged below the spinneret. It was introduced into a high-speed airflow traction device and stretched and solidified at a speed of about 4000 m / min to obtain a continuous filament group of about 2.5 denier.

The continuous long fiber group is jetted together with the high speed air flow from the high speed air flow traction device, and the continuous long fiber opening reflection plate (made of copper)
After the collision, the high-speed airflow straightening device (face-to-face spacing 20 mm, length 100 mm, vertical distance between the end of the device and the net conveyor 300 mm, angle parallel to the continuous long fiber opening reflecting plate,
It was introduced to and deposited on a net conveyor moving at a speed of 58 m / min. This makes the sheet width 210
A nonwoven web having a basis weight of 0 g and a basis weight of 30 g / m ² was continuously obtained. Then, the upper stage was a hot embossing roll and the lower stage was a smooth roll. At this time, the engraving of the hot embossing roll was round, the diameter was 0.6 mm, the bonding area ratio was 7%, and the surface temperature of the roll was 145 ° C.

Comparative Example 1 A spunbonded non-woven fabric was obtained in the same manner as in Example 1 except that the high-speed airflow rectifier was not installed.

Comparative Example 2 A spunbonded non-woven fabric was obtained in the same manner by using the same apparatus as in Example except that only the plate-like material on the lower side of the high-speed airflow rectifier was installed.

Comparative Example 3 A spunbonded non-woven fabric was obtained in the same manner by using the same apparatus as in Example except that only the plate-like material on the upper side of the high-speed airflow rectifier was installed.

The spunbonded nonwoven fabrics obtained in Examples and Comparative Examples 1 to 3 were subjected to the following tests to evaluate their quality. Table 1 shows the results.

[Table 1]

The CV values in Table 1 and the appearance (texture) evaluation methods are as follows. (1) CV value: 5 ears of the obtained spunbonded nonwoven fabric
After removing each 0 mm, it was cut into a width of 25 mm in the lateral direction and a length of 500 mm in the flow direction, the weights of these were measured, and the average value and standard deviation were obtained, and the standard deviation / average as CV value (%) The value was shown by 100. (2) Appearance (texture): 22 monitors performed visual evaluation. The appearance (texture) of the sample was evaluated on the basis of the five levels shown in Table 2 and the average value was obtained.

[0029]

[Table 2]

As is clear from Table 1, the spunbonded non-woven fabrics according to the examples have a markedly smaller CV value than the comparative example 1, that is, the spotted spots are markedly reduced, and as a result, the texture is very excellent. It has become a thing. Further, when only one of the plate-like objects of the high-speed airflow rectifying device is installed as in Comparative Examples 2 and 3, the non-uniformity in the weight is reduced and the texture is improved as compared with Comparative Example 1, but it is compared with the Examples. And the effect is reduced to half or less.

[0031]

As described above, according to the method of the present invention, continuous long fibers obtained by melt-spinning a thermoplastic resin in a blind shape from a spinneret in the process of obtaining a long fiber nonwoven fabric made of continuous long fibers. In the step of obtaining a non-woven web by pulling with a high-speed airflow pulling device having a rectangular cross section for thinning and stretching, colliding this with a reflection plate for continuous long fiber opening, and then depositing it on a net conveyor. By providing a straightening device composed of a pair of substantially parallel plate-like objects for straightening the high-speed air flow that pulls the continuous long fibers at a position below the reflection plate for continuous long fiber opening, the traveling direction of the long fiber net conveyor. It is possible to guide and deposit the long fibers on the net conveyor without stalling and spreading the long fibers. As a result, a spunbonded nonwoven fabric having a good basis weight and a uniform basis weight distribution can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus used for carrying out a spunbonded nonwoven fabric manufacturing method of the present invention.

FIG. 2 is an explanatory diagram of a flow of a high-speed air flow in the vicinity of a continuous long fiber opening reflecting plate in an apparatus used for performing a conventional spun-pond nonwoven fabric manufacturing method.

FIG. 3 is an explanatory view of the flow of high-speed airflow in the vicinity of the reflection plate for continuous long fiber opening and the high-speed airflow rectifier of the apparatus shown in FIG.

[Explanation of symbols]

 1 Spinneret 2 Continuous long fiber group (before ejection) 3 High-speed air flow traction device 4 Reflection plate for continuous continuous fiber opening 5 High-speed air flow straightening device 6 Continuous long fiber group (after ejection) 7 Net conveyor 8 Nonwoven web 9 High-speed air flow

Claims (1)

[Claims] 1. A reflection plate for continuous continuous fiber opening, which is obtained by drawing a continuous long fiber obtained by melt-spinning a thermoplastic resin into a blind shape from a spinneret by drawing with a high-speed air flow drawing device having a rectangular cross section and thinning it. In the step of obtaining a nonwoven web by depositing on a net conveyor after being collided with, a pair of a pair of rectifying a high-speed air flow for pulling the continuous long fibers, which is provided below the reflection plate for continuous long fiber opening. By suppressing the diffusion of long fibers in the traveling direction of the net conveyor by passing between the pair of plate members of the rectifying device made of plate members that are substantially parallel to each other, and guiding the long fibers onto the net conveyor without stalling. A method for producing a spunbonded non-woven fabric comprising continuous long fibers, which comprises depositing.