JPS6285062A - Production of web comprising long fiber - 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 (Industrial Field of Application) The present invention allows spinning, drawing and web formation to be carried out continuously. The present invention relates to a long fiber nonwoven fabric manufacturing method called the so-called spunbond method.

(Conventional technology) Manufacture of long fiber nonwoven fabric by spunbond method.

Special Publication No. 42-23998 and Special Publication No. 49-6786
This is a well-known technique as seen in the above publication. Usually, the mechanical properties (tensile strength, tear strength, etc.) of spunbond nonwoven fabrics are measured separately for the web movement method (hereinafter referred to as direction) and the width direction.

Now, in many applications, the mechanical properties of nonwoven fabrics are required to be balanced to some extent in the direction and width direction, that is, to have no directionality.

The filament is deposited by air jet.

In order to generate fiber separation due to electrical repulsion, it is common to be electrostatically charged before being deposited in two dispersions.

The filament deposition conditions are therefore influenced electrically and aerodynamically.

That is, it is spatially uniformly distributed by the electrical anti-fa force, while being dominated by the movement of the airflow surrounding the filament. The direction of filament flow due to this movement of airflow often coincides with the longitudinal direction of the web, but for this reason, the tensile strength of the web is significantly biased in the longitudinal direction compared to the web width direction. and become stronger. In the above-mentioned Japanese Patent Publication No. 42-23998, this air flow is alleviated by powerful suction from below the conveyor net.

It is said that the directionality of the mechanical properties of the web, that is, the difference in strength between the direction and the width direction, is eliminated. Note that the above-mentioned Japanese Patent Publication No. 49-6786 also describes a method for stabilizing a web in which the suction force is gradually reduced in the direction within the web.

By the way, today, wide nonwoven fabrics with a maximum width of more than 5 meters are being made using the spunbond method.

(Problems to be Solved by the Invention) The present inventors have discovered that when a wide nonwoven fabric of more than 3 m in width is manufactured by the spunbond method, the mechanical properties in the direction of the web of the nonwoven fabric are I experienced that significant differences tend to occur in different parts of the web in the width direction, and this difference is caused by differences in the way the filaments flow (the degree of flow in the direction within the web) in different parts of the width. I found out that there is. The factors that affect the degree of directional flow in the filament web are:
The amount of charge on the filament group ejected from the group.

There are at least four types, including: ■Characteristics of each jet, ■Differences in the degree of interference between jets, and ■Differences in the air suction force from the bottom of the hair net in different parts. Furthermore, regardless of the influence of any factor, if you take advantage of the fourth difference in partial attraction power.

It was discovered that the flow direction of the filaments in the width direction of the web can be made almost uniform.

(Means for Solving the Problems) That is, one aspect of the present invention is to form a web by depositing a large number of synthetic fiber filaments from a plurality of jets on a wire mesh belt conveyor.
In the Li2 long fiber non-weaving method, a suction device located at the bottom of the old belt conveyor that suctions air from each jet connects a plurality of sections in the width direction of the web, each of which can independently increase or decrease the suction force. The gist of the present invention is a method for producing a web made of long fibers, which is characterized in that the strength of the suction force from the section is locally adjusted in the width direction of the web.

By using the method of the present invention, it is possible to manufacture a web with uniform directionality by adjusting the suction force of each section arranged in the width direction of the web.

This partial adjustment of the suction force in the width direction.

You can also adjust the suction force by arranging the required number of rectifier plates with variable suction area (opening area) in the width direction using a set of two perforated plates (upper and lower), or by adjusting the angle of baffle plates attached to each section. It is also possible to perform the adjustment by means of a so-called suction damper, or by a combination of these.

Considering practicality, an adjustment method using only one set of upper and lower rectifying plates with variable aperture area is simple and preferable.

The number of independent sections may be selected as required, but it is appropriate that about 7 to 25 sections be arranged in the width direction of the web.

It is preferable that the width of the suction device be slightly wider than the width of the web, but if it is too wide or too narrow, the uniformity of the web will be impaired, so it is more preferable that the width of the suction device be 0.2 m to 0.5 m wider than the width of the web. .

It is appropriate that the length of the suction device is about 2 to 3 m in the longitudinal direction of the web, and it is also possible to provide a plurality of independent suction systems in the longitudinal direction of the web.

The method of the invention will now be explained in more detail with reference to one drawing.

FIG. 1 is a cross-sectional view of a suction device showing an example of a web manufacturing device used in the method of the present invention, as viewed from a plane perpendicular to the direction of movement of a belt conveyor. After the web is jetted and deposited on a wire mesh belt conveyor 1 by an air jet (not shown).

The air flows through a rectifying perforated plate 2, which is a pair of upper and lower plates rubbed together.
and is sucked into the suction duct 4 via the suction damper 3. The width of the suction device refers to the width at which the perforated rectifier plate or suction damper is installed. In addition, this suction device consists of multiple sections whose suction force can be adjusted independently, and the suction force can be changed depending on the angle of the baffle plate of the suction damper, the perforated surface of the perforated rectifier plate, and the bond. It is possible.

FIG. 2 is a plan view of an example of a perforated rectifying plate used in a damper, and 5 indicates an open hole portion.

(Function) The movement of the airflow surrounding the filament is affected by the suction from below the hair net.

The directionality of the mechanical properties of the web can be adjusted by adjusting the strength of this suction force. When manufacturing a wide nonwoven fabric by the spunbond method, the present invention makes it possible to reduce variations in the mechanical properties of the nonwoven fabric in the width direction of the web by performing this adjustment in the width direction of the web.

(Example) Next, the present invention will be explained in detail with reference to Comparative Examples and Examples.

Comparative Example Phenol/tetrachloroethane l: 1? n combination 7
A 15-spindle nozzle plate made of polyethylene terephthalate with an intrinsic viscosity of 0.687 arranged in a row in two width directions (48 holes each, discharge 1285 g/min, weight)
The pressure is 3.0kg/CJ for each weight.
The filaments were taken up by multiple jets, and the resulting filaments were further given an electrostatic charge, and then received on a wire mesh belt conveyor that moved in one direction, and a 5 m wide web was deposited on the wire mesh.

In addition, a suction device shown in FIG. 1 consisting of 12 sections was installed at the bottom of the belt conveyor, and the opening degree of the perforated rectifier plate and the suction damper was set to the maximum.

Furthermore, by heat-pressure welding with an embossed roll with an engraved pattern, an acrylic ester binder is uniformly applied to this web so that the solid content is 1/6 of the weight of the polymer filament, and after drying. After further heat treatment and line speed adjustment, this was rolled up to obtain a roll-cured sheet. The average denier of the filament is approximately 10 de
n, the weight of the sheet was 120 g/m. From this 5 m wide rolled sheet, two samples of 5 m width x 1 m length were randomly cut out and designated as samples A and B, respectively. Divide both samples into 10 equal parts in the width direction of the web, and divide them into 10 pieces from left to right in the direction of web flow.
I marked it with a value of 0. 10 from approximately the center of each part divided into 10 equal parts
Prepare one sample file for tensile test. Cough sample 30cm long in the long direction 1 5cm in the width direction of the web
Let it be n. All samples from each part of A and B were tested using a constant speed extension type tensile tester "Autograph" (manufactured by Shimadzu Corporation).
A tensile test was conducted using The tensile test conditions were: chuck size 3.8cm x 5.1c+n, pneumatic operation, distance between upper and lower chucks (measurement length): 20cm, tension speed: 20cm/min, full scale: 100 kg.
And so.

Table 1 is. These are the results of a longitudinal strength test for samples A and B. Sample A. In both cases, the longitudinal strength near both ends was high, and the longitudinal strength at the center was uniformly low.

Table 1: Strength of nonwoven fabric in the center direction (comparative example) Example 1 From the data analysis of samples A and B, the dampers of each of the suction sections divided into 12 in the width direction.

A sheet was made under exactly the same conditions as the comparative example, except that both ends were fully opened, the area immediately inside them was opened to 80%, and each section from the center was all opened to 1/3.

Randomly draw 5m width x 1 from the sheet roll you made.
Cut out a sample of m length and call it sample C.
A longitudinal tensile strength test was conducted in exactly the same manner as in the comparative example.

The results are shown in Table 2.

Example 2 After the completion of Example 1, the suction damper was fully opened in all zones. First, the area of each hole in the current plate (one set of two plates, top and bottom rubbed together) above the damper was adjusted. In other words, the adjustment is 38% for both sides, and 27-31% for the area just inside.

Furthermore, the upper and lower perforated plates were adjusted so that the inner 8 zones had an open area of 13 to 19%. The sheet was manufactured again under the same conditions as in Example 1 except for the above conditions, and samples of 5 m width x 1 m length were randomly taken. This is called sample D.

It was subjected to a tensile strength test in exactly the same manner as the comparative example.

The results are shown in Table 2.

Table 2 Strength of nonwoven fabric in the center direction (Examples) (Effects of the invention) According to the present invention, a nonwoven fabric sheet with less bidirectional isotropy in two mechanical properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of a suction device, and FIG. 2 is a plan view of an example of a rectifying perforated plate used in a damper. 1----Belt conveyor 2---Porous rectifier plate 3---Suction damper 4---1--Suction duct

Claims (3)

[Claims] (1) A method for producing a long fiber nonwoven fabric in which a web is formed by jetting and depositing a large number of synthetic fiber filaments from a plurality of jets onto a wire mesh belt conveyor,
The suction device, which is located at the bottom of the belt conveyor and sucks air from each jet, is composed of a plurality of sections in the width direction of the web that can independently increase and decrease the suction force, and the suction force from the sections can be increased or decreased. A method for producing a web made of long fibers, characterized by locally adjusting the web width in the width direction of the web. (2) The method according to claim 1, wherein the strength of the suction force is adjusted by a suction damper. (3) The method according to claim 1, wherein the strength of the suction force is adjusted by shifting two upper and lower rectifying perforated plates to change the aperture area.