JPH0931820A - Production of nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain filament nonwoven fabric by drawing and thinning a continuous filament group prepared by melt spinning in a reed screen state, opening and piling the opened filaments on a net conveyor slidable in the direction perpendicular to the advance direction, having improved a strength characteristic ratio in the longitudinal/lateral directions and weight unevenness. SOLUTION: A thermoplastic resin such as polypropylene, etc., is subjected to melt spinning through a spinneret 1 into a reed screen state to give a continuous filament group 2, which is drawn and thinned by a high-speed air flow drawing device 3 having a rectangular section. The filament group is hit to a reflecting plate 5 for opening, opened, collected and piled on a net conveyor 6 sliding in a given cycle in a direction B perpendicular to an advance direction A to give the objective continuous filament nonwoven web 7.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a continuous fiber non-woven fabric composed of a continuous continuous fiber group made of a thermoplastic resin, and more specifically, the strength characteristic ratio in the longitudinal and transverse directions is improved, Moreover, the unit weight unevenness (streak unevenness)
The present invention relates to a method for producing a spunbonded non-woven fabric having a small amount of waste.

2. Description of the Related Art The spunbond method is one of the methods for obtaining a nonwoven fabric from a continuous fiber group obtained 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 airflow traction device. In recent years, demand has been increasing as a method for obtaining a nonwoven fabric at a low cost, which is a method of forming a nonwoven web by collecting and depositing it on a conveyor. However, in this method, the continuous long fiber group ejected together with the high-speed air flow is collected and accumulated by the net conveyor running in the same direction as the fiber group, so that the orientation of the fibers constituting the nonwoven web tends to be the longitudinal orientation. , Therefore the strength properties of the resulting sheet are, for example,
The breaking strength in the longitudinal direction is large, but the breaking strength in the lateral direction is very small.This is remarkable when the speed of the manufacturing equipment is increased, that is, as the productivity is increased. Appeared. In addition, when continuously looking at a continuous long fiber group that has been uniformly opened by some method, there is a difference in the fiber density due to the influence of the flow velocity difference in the high-speed airflow, etc. When the groups were collected and accumulated in the vertical orientation, unevenness in areal weight (streak unevenness) in the width direction appeared. As a method of eliminating the longitudinal orientation of the fiber which causes the above-mentioned defects, there is a method of sliding the lower part of the integral collision plate at a speed of 150 times or more per minute as disclosed in JP-A-60-155764, and Japanese Patent Publication No. 6- As in 47780, there is a method of controlling the fiber orientation by using a sliding channel. However, in the former case, since the lower part of the integral collision plate is slid at high speed, a turbulent flow is generated in the high-speed airflow, and this turbulent flow may disturb the flow of the uniformly opened fiber group, which is preferable. Absent. Moreover, it is not preferable to make the sliding direction the same as the traveling direction of the net conveyor, because there is a risk of promoting longitudinal orientation of the fibers. Even in the latter case, sliding the channel is not preferable because it may disturb the flow of the continuous long fiber group that has been uniformly opened in the preceding process, and it is not preferable. When an airflow traction device is used, it is necessary to slide only the integrated channel portion, or to provide another channel below the high-speed airflow traction device and slide it. However, this is not preferable because of problems such as complexity of structure and installation space. In addition, when a method of frictionally charging the continuous long fiber group using a reflector or the like to open the fiber after the high-speed airflow traction device is used, the ejection angle from the reflector to the net conveyor becomes important here. Large sliding of the long fiber group is not preferable because it may disturb the formation of the obtained sheet.

SUMMARY OF THE INVENTION In order to overcome the above-mentioned drawbacks of the prior art, the present invention provides a net conveyor for collecting and depositing a continuous long fiber group that has been uniformly opened by some method. Longitudinal orientation of the fibers is eliminated by sliding in a direction perpendicular to the direction, thereby improving the strength characteristic ratio in the longitudinal and transverse directions, and obtaining a spunbonded non-woven fabric with reduced unevenness of weight (stripe unevenness). It is what

That is, according to the present invention, a continuous long fiber group obtained by melt-spinning a thermoplastic resin in a blind shape from a spinneret is drawn by a high-speed air flow drawing device having a rectangular cross section to be thinned and drawn, A net conveyor that collects and deposits continuous long fiber groups in the process of collapsing and opening the continuous long fiber group reflecting plate to collect and deposit it on a net conveyor to obtain a nonwoven web. By sliding in a direction perpendicular to the traveling direction of the net conveyor to collect and accumulate the fibers on the net conveyor without disturbing the flow of the continuous long fiber group that has been uniformly opened and ejected, and thereby longitudinally orienting the fibers. The present invention relates to a method for producing a spunbonded nonwoven fabric, which is characterized in that the strength characteristic ratio of the long-fiber nonwoven fabric thus obtained is improved in the machine direction and the transverse direction, and the nonuniformity of the basis weight (streak unevenness) is also reduced. Here, a method for producing a spunbonded nonwoven fabric according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a spunbonded nonwoven fabric manufacturing apparatus according to the present invention. In FIG. 1, a spinneret 1 is a spinneret in which spinning holes are arranged in a straight line and arranged in a plurality of rows, and a melt-spun continuous filament group 2 has a rectangular cross section with a rectangular cross section. 3 and is thinned and drawn while traveling between the spinneret 1 and the high-speed airflow traction device 3. The continuous long fiber group 4 ejected from the high speed airflow pulling device 3 together with the high speed airflow is collided with the continuous long fiber group opening reflection plate 5 provided below the high speed airflow pulling device 3 to be charged and opened. After that, the continuous long fiber group 4 is guided to the net conveyor 6 by a high-speed air flow to form a non-woven web 7. At this time, the net conveyor 6 which collects and deposits the continuous long fiber group 4 has a traveling direction (arrow A). ), The collection surface of the net conveyor 6 apparently moves in a wavy manner. Therefore, the continuous continuous fiber group 4 is also collected and deposited on the net conveyor 6 while drawing a wavy shape, so that the obtained nonwoven web 7 is obtained.
The longitudinal orientation of the fibers inside is eliminated. FIG. 2 is a side view schematically showing a mechanism for sliding the net conveyor of the present invention, and FIG. 3 is a plan view. In FIG. 2, the net conveyor 6 traveling endlessly includes a driving roll 8, a turning roll 9, a guide roll 10, and a roll 1.
It is supported by 1, 12 and support bases 13, 14. The lower part of the support base 14 and the upper part of the column 15 are connected by a rail 16 as shown in FIG. Further, the drive roll 8, the guide roll 10, and the suction box 1
7 is fixed to the support base 13, and the turning roll 9, the guide rolls 11 and 12, and the suction box 18 are fixed to the support base 14. In FIG. 3, a crank shaft 20 is attached to the rotary motor 19, and sliding rods 21 and 22 are connected to a crank portion of the crank shaft 20. The sliding rods 21 and 22
The other tip of is connected to the support base 14. Therefore, when the rotary motor 19 is operated, the crankshaft 20 rotates and the sliding rods 21 and 22 connected to the crankshaft 20 reciprocate. Therefore, the support base 14 connected to the sliding rods 21 and 22 also slides on the support column 15 along the rail 16. At this time, the support 14
Turning roll 9 and guide roll 1 fixed to
Since 1 and 12 also slide, the net conveyor 6 supported by these rolls also slides together with the support 14. By the way, the sliding width of the net conveyor 6 is optional, but is preferably 3 to 12 cm. If the sliding width is smaller than 3 cm, the effect of sliding the net conveyor 6 hardly appears, and if it is larger than 12 cm, the ears of the product become large and the yield is deteriorated, which is not preferable. The sliding speed of the net conveyor 6 should be arbitrarily set according to the sheet manufacturing speed and the sliding width of the net conveyor, and according to the required strength characteristic ratio in the longitudinal and lateral directions of the obtained sheet. If it is faster than 120 cycles (1 cycle = 1 round trip) per minute, the equipment cost and the power cost will be increased, which is not preferable.

As described above, according to the present invention, in the process of obtaining a continuous fiber non-woven fabric comprising continuous continuous fiber groups, a continuous continuous fiber group obtained by melt-spinning a thermoplastic resin in a blind shape from a spinneret is cross-sectioned. Is pulled by a rectangular high-speed airflow pulling device to be thinned and stretched, which is collided with a continuous long fiber group reflecting plate for fiber opening and opened, and then collected and deposited on a net conveyor to form a nonwoven web. In obtaining, it is possible to eliminate the longitudinal orientation of the fibers in the long fiber nonwoven fabric obtained by sliding a net conveyor for collecting and depositing a continuous long fiber group in a direction perpendicular to the traveling direction of the net conveyor, Therefore, the strength characteristic ratio in the longitudinal and transverse directions of the long-fiber nonwoven fabric is improved, and further there is an effect that it is possible to reduce the unevenness of weight (streak unevenness).

【Example】

Example 1 Using the apparatus shown in FIGS. 1 to 4, 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, 1 row).
The number of holes in a row is 350, the length of a row is 2000 mm, and the hole diameter is 0.
6 mm) and melt-spun at a discharge rate of 1 g per minute per hole, and the continuous long fiber group is introduced into a high-speed air flow traction device arranged below the spinneret to be stretched and solidified to obtain a continuous length of about 3.0 denier. A fiber group was obtained. After that, the continuous filament group is 5 per minute
It was collected and deposited on a net conveyor moving at a speed of 2 m. The sliding width of the net conveyor at this time was 5 cm, and the sliding speed was 60 cycles per minute. As a result, a nonwoven web having a sheet width of 2000 mm 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. Example 2 The sliding width of the net conveyor is 3 cm, and the sliding speed is 1 per minute.
A spunbonded nonwoven fabric was obtained in the same manner as in Example 1 except that the cycle was 00. Example 3 A spunbonded nonwoven fabric was obtained in the same manner as in Example 1 except that the sliding width of the net conveyor was 12 cm and the sliding speed was 30 cycles per minute. Comparative Example 1 A spunbonded nonwoven fabric was obtained in the same manner as in Example 1 except that the net conveyor was not slid. Comparative Example 2 A spunbonded non-woven fabric was prepared in the same manner as in Example 1 except that the sliding width of the net conveyor was 1 cm, which was the lower limit of the preferable sliding width range, and the sliding speed was 100 cycles per minute. Obtained. Comparative Example 3 All the examples except that the sliding width of the net conveyor was 15 cm, which exceeded the upper limit of the preferable sliding width range, the sliding speed was 30 cycles per minute, and the obtained sheet width was 1900 mm. A spunbonded nonwoven fabric was obtained in the same manner as in 1. The spunbonded nonwoven fabrics obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to the following tests to evaluate their quality. Table 1 shows the results.

[Table 1] The longitudinal / transverse fracture strength ratio, CV value, appearance (texture), and yield evaluation method in Table 1 are as follows. (1) Longitudinal / horizontal breaking strength ratio: The breaking strength in the longitudinal and lateral directions of the sheet was obtained from the average value of N = 10, and the ratio was defined as the breaking strength in the longitudinal direction / the breaking strength in the lateral direction. (2) CV value: after removing the selvages of the obtained spunbonded nonwoven fabric, the width was 25 mm in the lateral direction and 50 in the flow direction.
Cut to a length of 0 mm, weigh these, find the average value and standard deviation, and calculate the CV value (%) as standard deviation /
It was calculated from the average value × 100. (3) Appearance (texture): 21 monitors conducted visual evaluation. The appearance (formation) of the sample was evaluated in five steps shown in Table 2, and an average value was obtained. (4) Yield: Calculated from product weight / weight of raw material used × 100 (%). However, the product weight was the weight with the ears removed from the obtained spunbonded nonwoven fabric.

[Table 2] As is clear from Table-1, the spunbonded nonwoven fabrics according to Examples 1 to 3 have a significantly improved strength / property ratio in the longitudinal / transverse directions as compared with Comparative Example 1, and also have an improved CV value, resulting in an appearance. Good evaluation has been obtained. Further, in Comparative Example 2, since the sliding width of the net conveyor is small, the effect is not so remarkable as compared with Comparative Example 1. In addition, Comparative Example 3
In each item, each item has been improved to the same level as that of the example, but the yield is low because the width of the ears is large, and it is not preferable to provide a product at low cost.

As described above, according to the present invention, in the process of obtaining a continuous fiber non-woven fabric comprising continuous continuous fiber groups, continuous continuous fiber groups obtained by melt-spinning a thermoplastic resin in a blind shape from a spinneret are cross-sectioned. Is pulled by a rectangular high-speed airflow pulling device to be thinned and stretched, which is collided with a continuous long fiber group reflecting plate for fiber opening and opened, and then collected and deposited on a net conveyor to form a nonwoven web. In obtaining the above, by sliding a net conveyor for collecting and depositing a continuous long fiber group in a direction perpendicular to the traveling direction of the net conveyor, the longitudinal orientation of the fibers in the obtained long fiber nonwoven fabric can be eliminated. Therefore, the strength characteristic ratio in the longitudinal and transverse directions of the long-fiber nonwoven fabric is improved, and there is an effect of further reducing the unevenness of weight (straightening).

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a schematic side view of a sliding mechanism of a net conveyor according to the present invention.

FIG. 3 is a schematic plan view of a sliding mechanism of a net conveyor according to the present invention.

FIG. 4 is an enlarged view of a connecting portion between a support base and a support in the present invention.

[Explanation of symbols]

 1: Spinneret 2: Continuous long fiber group (before jetting) 3: High-speed air flow traction device 4: Continuous long fiber group (after jetting) 5: Continuous long fiber group Reflecting plate for fiber opening 6: Net conveyor 7: Nonwoven web 8: Drive roll 9: Turning roll 10, 11, 12: Guide roll 13, 14: Support stand 15: Support 16: Rail 17, 18: Suction box 19: Sliding motor 20: Crankshaft 21, 22: Sliding rod

Claims (1)

[Claims] 1. A continuous long fiber group obtained by melt-spinning a thermoplastic resin in a blind shape from a spinneret in a step of obtaining a continuous fiber non-woven fabric comprising a continuous long fiber group is drawn by a high-speed air flow drawing device having a rectangular cross section. Then, it is thinned and stretched, and it is collided with a reflecting plate for fiber opening to open the fiber, and then it is collected and deposited on a net conveyor to collect a continuous long fiber non-woven web. A method for producing a spunbonded non-woven fabric, which comprises sliding a net conveyor to be deposited on the net conveyor in a direction perpendicular to the traveling direction of the net conveyor.