JPS63175158A - Production of uniform long fiber nonwoven fabric - 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 C. Industrial Application Field The present invention relates to a method for producing a long fiber nonwoven fabric. More specifically, the present invention relates to a method for producing a uniform long-fiber nonwoven fabric with particularly low anisotropy and a small rate of variation in area weight.

[Conventional technology]

Various methods for producing long fiber nonwoven fabrics mainly composed of continuous filaments have been proposed and applied to industrial production. In most of these, continuous filaments of thermoplastic fibers are melt-spun, collected to form a long-fiber nonwoven web, and then the filaments are bonded to produce a long-fiber nonwoven fabric mainly made of long fibers. It is. but,
In these methods, in order to spread the melt-spun filaments and obtain a sheet with an industrially required width, a rectangular spinning device that is long in the width direction is provided, or a plurality of spinning devices are arranged in the width direction. This method is commonly used, and due to mutual interference between filaments and spindles, partial turbulence of the fluid used for spinning, or repulsion or attraction due to static electricity, the deposition of the wap becomes uneven, resulting in uneven basis weight. There was a fatal problem in that the size of the Furthermore, in a nonwoven woven fabric obtained by melt-spinning a group of continuous filaments and collecting them, the direction of the filaments constituting the filament is biased toward the traveling direction of the woven fabric, and the long-fiber nonwoven fabric obtained from such a woven woven fabric is difficult to obtain. had a fatal defect (so-called anisotropy) that made it easy to crack in the length direction.

The present invention aims to solve the above problems. That is, the aim is a method for efficiently producing a uniform long-fiber nonwoven fabric with small unevenness in area weight and extremely low anisotropy.

[Means for solving problems]

As a result of long-term intensive studies regarding these problems, the present inventor has finally arrived at the present invention. Namely, the present invention provides a long-fiber nonwoven fabric mainly consisting of continuous filaments in a method for producing a long-fiber nonwoven fabric. A first step of guiding the webs to a cross wrapper and laminating them, a second step of stretching the laminate of long fiber nonwoven webs formed in the first step, and a long fiber nonwoven web after the second step. This is a method for producing a uniform long-fiber nonwoven fabric, characterized in that it includes at least a third step of bonding a laminate of webs.

The present invention will be explained in detail below.

In the present invention, it is an essential requirement that a first step is included in which a long fiber nonwoven web (hereinafter referred to as a web) mainly consisting of a group of continuous filaments is guided to a cross lumbar and laminated.

In the second step, a mainly uniform basis weight distribution is formed. That is, in this process, the wap is suspended in a cross ramper on a floor-conveyor that moves in a direction approximately perpendicular to the supply direction, reciprocating in an approximately constant stroke, and is folded back at both ends to form approximately the same shape. A laminate of long-fiber nonwoven webs stacked with deviations between the corners (hereinafter referred to as a laminate)
is formed. In this case, the lamination conditions are as shown in the following equations (1) and (2) so that the final product meets the target specifications.
It is preferable to select based on the relationship expressed by equation (3).

N=Y/X・・・・・・・・・・・・・・・ (1) v=
(SxW) / (NxD) ・---・−(2)Y
=FX (1/R,) x (1/nz)...
(3) However, N: Number of laminated layers Ys fiN Average basis weight of the body (g/m) X: Average basis weight of the wap (g/m)
1n) S: Supply speed of wap (m/win) W: Width of wap (m) D = Width of laminate (m) F: Target average basis weight of long fiber nonwoven fabric (g#+?) R1: According to the present invention Area ratio before and after stretching in the second step (stretched part area/area after stretching) R2: Area ratio before and after bonding in the third step of the present invention (
Bonded area/area after bonding) The variation rate of basis weight, which is one of the coefficients expressing the uniformity of long fiber nonwoven fabric, tends to decrease as the number of laminated layers in the first step of the present invention increases, and it almost decreases when the number of laminated layers is about 60. Since saturation occurs, the number of laminated layers is preferably in the range of 3 to 60, although it is not particularly limited.
In consideration of productivity, the number of laminated layers is particularly preferably in the range of 10 to 30.

In the present invention, a second step of subsequently stretching the web laminate is included as an essential requirement.

In the second step, the anisotropy of tear strength is mainly corrected. That is, in the first step, the waps with the filament direction biased in the length direction are stacked in an intersecting manner, so the laminate that is discharged has the filament direction biased in the width direction. Since the bonding process results in a long fiber nonwoven fabric that is easily torn in the width direction, the laminate is mainly stretched in the length direction in the second step. Regarding the stretching device, it is preferable to use a device in which a plurality of transfer devices configured to grip and transfer the sheet-like material are arranged so that the transfer speed thereof increases in order in the direction of movement. It is more preferable to use a device configured to regulate the amount of film, and a method in which the stretching ratio in the length direction is made higher than the stretching ratio in the width direction using a biaxial stretching machine is more preferable because the quality is more stable. The stretching distance in the length direction, that is, the distance between a pair of transfer devices with different speeds or the distance between the axis tangents of a biaxial stretching machine, is preferably within the range of the following equation (4), and more preferably within the range of the following equation (5). is within the range of

L<W/2・・・・・・・・・・・・・・・ (4) L<
W/4・・・・・・・・・・・・・ (5) However,
L: Stretching distance in the length direction (m) The stretching Ig ratio is not particularly limited as long as it is selected so that the anisotropy of the long fiber nonwoven fabric satisfies the customer's requirements.

The present invention includes a third step of bonding the laminate that has undergone the second step. In the third step,
Mainly the symmetry formed in the first step and the second step is fixed. That is, in the present invention, the joining process is
A means for partially restraining the filaments that make up the laminate, with the aim of imparting practically sufficient morphological stability to the laminate, and includes high-speed fluid processing, adhesive treatment,
Fusion treatment, pressure bonding treatment, etc. are preferably applied depending on the application, and after impregnation with a solution or emulsion containing resin, solidification,
It is more preferable to use a drying method in combination as appropriate. The laminate that has gone through the third process is extremely resistant to tension during subsequent steps and partial external forces during transportation and storage, since the filaments that make up the laminate are constrained. Stable and maintains symmetry.

Furthermore, the material for the web used in the present invention may be any material that can form a long fiber non-woven web mainly consisting of continuous filaments, such as homopolymers and copolymers such as polyamide, polyester, polyolefin, polyphenylene, etc. selected from a mixture of these. The form of the filament is also not particularly limited. That is, it may be a single-component system or a multi-component system, and may be a core-sheath type composite, a sea-island type composite, or a split type composite. The filament group is not limited to being composed of the same kind of filaments, but may also be composed of a mixture of different kinds of filaments. The cross-sectional shape of the filament may be circular, elliptical, oblate, polygonal, or hollow, or may include a mixture of filaments with irregular cross-sections. The filament fineness is also not particularly limited. Also, as appropriate, in each process,
It goes without saying that natural or artificial short fibers may be mixed.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but this does not limit the present invention or impair the effectiveness of the present invention.

In addition, the evaluation values in the examples are values measured and calculated by the following method.

(1) Fabric weight and fabric weight variation rate Collect 400 square samples of 5CI11 on each side in a matrix of 20 rows in the width direction and 20 columns in the length direction,
Measure the weight of each individual, convert it to g/mJ, and calculate the average weight (g/mz
) and calculate the percentage value (%) for each average basis weight (
g/m2) and area weight variation rate (%).

(2) Tear strength: 7.5c in both width and length directions.
Ten rectangular samples with a length of 20 cm and a cut of 7°5 cm in the center in the horizontal direction were taken, and the tearing strength was measured at a tensile speed of 10 cm/min, and the average value was obtained for each direction. were calculated and defined as the tear strength in the width direction (kg) and the tear strength in the length direction (kg).

(3) Anisotropic width direction tear strength (kg) and length direction tear strength (kg)
The percentage (%) of the absolute value of the difference in kg) with respect to the average value was determined, and this was defined as the anisotropy (%).

Example 1 Using a direct web manufacturing device in which five spinning units mainly consisting of a melt spinning machine, an air ejector, and a reflector were arranged at intervals of 30 CI 11 in the traveling direction, nylon 6 continuous yarn with an average single yarn fineness of 0.9 denier was produced. A wap consisting of a group of filaments with an average basis weight of 4 g/m2 and a width of 50 cm was collected continuously, and then an oil agent (butyl sthialate = 6%, ethylene oxide adduct of lauryl alcohol: 4%) was collected on the wap. , phosphate antistatic agent: 1%, water:
89%) was applied at 4.5% to the weight of the wafer, and the material was fed to the cross wrapper at a feeding speed of 60 m/min, and the number of layers was 1.
5, a laminate with a width of 5 m was obtained at a discharge speed of 0.4 m/min.

The average basis weight of the laminate was 210.6 g/m''.Subsequently, the laminate was placed in an axial stretching device and stretched 1°3 in the length direction.
It was stretched 7 times. By stretching, the width of the laminate became 4.75 m, which was 0.95 times the width before stretching. Subsequently, the stretched laminate was introduced into a needle punching device, where it was bonded with a needle density of 300 wood/cI11 from the front and back sides, and after drying, the ears at both ends were cut off by 2 cm to give an average basis weight of 180 g/m. ”, a long fiber nonwoven fabric with a width of 4.46 m at a speed of 0
．． It was obtained at a speed of 5 m/min.

Comparative Example 1 Using a direct sea urchin manufacturing device, five spinning units mainly consisting of a melt spinning machine, an air ejector, and a reflector were arranged at 30 cm intervals in the direction perpendicular to the direction of travel (width direction). Consisting of 6 continuous nylon filaments with an average single filament fineness of 0.9 denier and an average basis weight of 162 g/m
2. Continuously collect 7 pipes with a width of 146 cm, and then apply the same oil as in Example 1 to the web at 4.5% of the weight of the web, and then introduce it to a needle punch device.
Bonding treatment was applied to the front and back sides at a needle density of 300 needles/ci, and after drying, the ears at both ends were cut out by 10 cm, and the long fiber nonwoven fabric with an average basis weight of 180 g/m" and a width of 1.26 m was dried at a speed of 1. 6 m/min.

Table 1 shows the properties of the long fiber nonwoven fabric on each side.

Table 1 [Effects of the Invention] As described above, according to the present invention, it is possible to efficiently provide a uniform long-fiber nonwoven fabric with particularly low anisotropy and a small rate of variation in basis weight. It is extremely large.

Claims (1)

[Claims] A method for producing a long-fiber nonwoven fabric includes a first step of guiding a long-fiber nonwoven web mainly consisting of a group of continuous filaments to a cross wrapper and laminating the same, and a laminate of the long-fiber nonwoven web formed in the first step. 1. A method for producing a uniform long fiber nonwoven fabric, comprising at least a second step of stretching a long fiber nonwoven web, and a third step of bonding a laminate of long fiber nonwoven webs that have undergone the second step.