JPH1077565A - Production of nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cylindrical nonwoven fabric of high rigidity by the use of thermoplastic resin fibers through continuous process. SOLUTION: First, a molten resin 1a is extruded from a nozzle 3 through a screw shaft 4 and molten resin fibers 1b are allowed to fall freely under spirally crimping; during the process, the fibers are entangled with one another and allowed to fall onto a forming surface 6 so as to continuously form a semi-fusion sheet-like nonwoven fabric 2a; subsequently, the nonwoven fabric 2a is pulled into a mold 10 and both ends of the nonwoven fabric 2a are raised through the inner periphery of the mold 10 to weld both the ends so as to be molded cylindrically; the resultant molded cylindrical nonwoven fabric 2b is continuously drawn, cooled and then cut to a specified length. By virtue of a series of the operations mentioned above, the objective cylindrical nonwoven fabric 2b of high rigidity is produced in a continuous way.

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 nonwoven fabric used for various filters and cushion materials, and more particularly, to a method for continuously producing a tubular or sheet-like nonwoven fabric made of thermoplastic resin fibers. To a nonwoven fabric manufacturing method.

[0002]

2. Description of the Related Art As a manufacturing method for continuously producing a sheet-like nonwoven fabric made of thermoplastic resin fibers such as polypropylene, a molten thermoplastic resin is extruded from the tip of a nozzle and naturally descends. A method is generally known in which a molten resin fiber is formed into a crimp shape by a heat injection method or the like during descent and entangled with each other. The sheet-shaped nonwoven fabric produced by this method is excellent in air permeability and durability, and is also excellent in elasticity by using soft resin fibers. Widely used for soundproofing materials, packing and filling materials.

[0003] The nonwoven fabric is used in the form of a sheet, or may be formed into a tubular shape depending on the use. Examples of the method for producing this cylindrical nonwoven fabric include a method in which a sheet-shaped nonwoven fabric manufactured in a fixed form is rolled into a cylindrical shape, and both ends thereof are connected to each other by a welding method or an adhesion method to form a cylindrical shape, or a cylindrical rotating body. A method is known in which a resin fiber having a crimp or curl is entangled with the outer periphery of the resin to form a tubular nonwoven fabric, and then the tubular nonwoven fabric is removed from a rotating body.

[0004]

The resin fibers of a sheet-like or tubular non-woven fabric are generally melt-blown, but the resin fibers immediately after the melt-blowing are straight molten polymers which are unsuitable as non-woven fabric fibers. In addition, the resin fibers are crimped by a heat jet flow or the like to entangle the resin fibers to produce a sheet-like nonwoven fabric. Such a manufacturing method can be performed continuously and continuously from the production of the resin fiber to the production of the tubular nonwoven fabric, but since there is a step of crimping the resin fiber immediately after production during the continuous production process, Need special equipment.

[0005] Further, in the case of a manufacturing method in which an existing sheet-like nonwoven fabric is rolled into a tubular shape to manufacture a tubular nonwoven fabric, the number of manufacturing steps including the step of manufacturing the sheet-like nonwoven fabric is increased, resulting in poor productivity. Further, when cutting out a sheet piece having a predetermined size for a tubular nonwoven fabric from the sheet nonwoven fabric, ear dust is generated, so that the yield of the material is poor, which is a factor of increasing the product cost. Further, in order to roll the sheet-like nonwoven fabric, the nonwoven fabric material must be a soft resin fiber, and as a result, the produced tubular nonwoven fabric is limited to a soft one, such as an underground filter or a drain pipe. A high-rigidity tubular nonwoven fabric that can withstand use in a place where a relatively large pressure is applied cannot be manufactured.

Further, a method for producing a cylindrical non-woven fabric which is formed by forming a non-woven fabric on the outer periphery of a cylindrical rotating body and then removing the non-woven fabric from the rotating body is as follows.
In order to manufacture a non-woven fabric having high rigidity, it is difficult to extract the non-woven fabric from the rotating body. Therefore, there is a problem that the degree of freedom in design such as the thickness and diameter of the tubular non-woven fabric is small.

As another method for producing a cylindrical nonwoven fabric, while the nonwoven fabric is wound in a semi-molten state around the outer periphery of the rotating body, the semi-molten cylindrical nonwoven fabric is pulled in the axial direction from the end of the rotating body to reduce the diameter. Japanese Patent Publication No. Hei 9-982 discloses a method for continuously producing a cylindrical nonwoven fabric having a predetermined diameter by elongating a conical shape while making the same.
No. 7, etc., this manufacturing method is easy to adjust the thickness and diameter of the tubular nonwoven fabric, but to expand the conical shape while reducing the diameter of the tubular nonwoven fabric from the outer periphery of the rotating body, It is not suitable for producing a nonwoven fabric having high rigidity.

It is an object of the present invention to provide a method for manufacturing a nonwoven fabric made of a thermoplastic resin fiber having a high rigidity in either a sheet shape or a tubular shape, in terms of process and equipment.

[0009]

The technical means for achieving the above object of the present invention is to push a thermoplastic molten resin in a nozzle toward a nozzle tip with a screw shaft to form a plurality of molten resin fibers from the nozzle tip. It is extruded in a spiral and allowed to descend naturally, and while the plurality of naturally descending molten resin fibers are entangled with each other, they are continuously collected on a molding surface at a fixed position below the nozzle to form a sheet-like semi-molten nonwoven fabric, This is to produce a nonwoven fabric by cooling.

[0010] The nozzle is used when producing a multiplicity of resin fibers by a melt spinning method. The nozzle has a large number of small-diameter holes at the tip, and the molten resin is screwed toward the nozzle tip. When the shaft is pressed, the molten resin is extruded from the hole at the tip and becomes molten resin fibers (molten polymer). To the molten resin fiber extruded from the nozzle tip, a turning moment is applied by extrusion of the screw shaft in the nozzle,
The resin fibers are naturally spirally crimped and the resin fibers are easily entangled with each other.
While the resin fibers naturally descend from the nozzle, they are entangled with each other and descend to the molding surface while forming a nonwoven fabric, and at the time of falling to the molding surface, the fibers are further entangled with each other to form a semi-molten sheet-like nonwoven fabric. Become.

The molding surface on which the molten resin fiber which naturally descends from the nozzle is suitably a liquid surface such as cooling water or an inclined surface of a slide such as Teflon which makes the nonwoven fabric slip easily. The spiral resin fibers descending to the molding surface are forcibly cooled or naturally cooled on the molding surface and further crimped, and the fibers are sufficiently entangled to form a semi-molten sheet-like nonwoven fabric.

[0012] The present invention also provides a cylindrical molding die disposed in a passage in which a sheet-like semi-molten non-woven fabric formed by descending on the molding surface moves along the molding surface. While continuously moving the sheet-like semi-molten non-woven fabric along the circumference, gradually raising both side ends of the semi-molten non-woven fabric on the inner periphery of the forming die and butt-welding the two ends together to form a sheet-like semi-molten non-woven fabric. The nonwoven fabric is continuously formed into a cylindrical shape.

Here, the molding die disposed on the molding surface is a large-diameter flared cylindrical body on the upstream side in the nonwoven fabric transport direction, and a semi-molten sheet from the large-diameter opening to the small-diameter opening. The nonwoven fabric is pulled and gradually formed into a tubular shape. When both ends of the semi-molten sheet-like non-woven fabric are lifted along the inner circumference of the mold and abutted in a cylindrical shape, the abutting ends are in a semi-molten state, so that the sheet-like non-woven fabric is naturally fused. Becomes The semi-molten tubular nonwoven fabric thus formed is drawn out from the small-diameter side opening of the mold and cooled, and various rigid tubular nonwoven fabrics in which semi-molten resin fibers are solidified are continuously produced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the method of the present invention will be described with reference to FIGS.
A description will be given with reference to an example of the embodiment.

FIG. 1 (A) shows a continuous production of a semi-molten sheet-like nonwoven fabric 2a by entanglement of a plurality of molten resin fibers 1b which are continuously extruded from a nozzle 3 and naturally descend. An outline of a tubular nonwoven fabric manufacturing apparatus for continuously manufacturing a tubular nonwoven fabric 2b from 2a is shown. The manufacturing apparatus includes a downwardly directed nozzle 3, a water tank 8 installed directly below the nozzle 3, and a molding die 10 arranged along a molding surface 6 formed by a water surface of water 7 stored in the water tank 8.

At the lower end of the downward nozzle 3, a number of small-diameter holes (not shown) are formed. A screw shaft 4 is installed vertically in the nozzle 3, and when the molten thermoplastic resin 1 a is supplied into the nozzle 3 from a resin supply port 5 above the nozzle 3, the molten resin 1 a is rotated by the rotation of the screw shaft 4. 3 and is extruded from the small diameter hole at the lower end of the nozzle 3 to form a thin molten resin fiber 1b. The molten resin 1a is, for example, a polyolefin resin such as polyethylene, a polyester resin, a polyamide resin, or the like.

A turning moment by the screw shaft 4 is applied to the multiplicity of molten resin fibers 1b extruded from the nozzle 3 by the screw shaft 4, and while being extruded from the nozzle 3, is naturally spirally crimped and directly below. Descends naturally. By appropriately selecting the density of the multiplicity of molten resin fibers 1b naturally descending from the nozzle 3, the spirally crimped molten resin fibers 1b come into contact with each other and become entangled with each other to form a fiber aggregate close to a non-woven fabric. To the molding surface 6 (water surface).

The molten resin fiber 1b that has fallen to the molding surface 6 is cooled, further crimped and entangled, and a number of fibers gather to form a fiber aggregate. When the specific gravity of the molten resin fiber 1b is smaller than or substantially equal to that of water, the molten resin fiber 1b floats on the water surface and becomes entangled with the semi-molten nonwoven fabric 2a. When this semi-molten nonwoven fabric 2a is pulled in the direction of the mold 10 along the water surface,
The semi-molten nonwoven fabric 2a continuously formed by the continuous drop of the molten resin fiber 1b moves on the water surface and becomes a sheet.

Molten resin fiber 1 which naturally descends from nozzle 3
The thickness, width, and fiber density of the semi-molten sheet nonwoven fabric 2a can be freely adjusted by adjusting the density, width, and descent speed of the semi-molten sheet nonwoven fabric 2a on the water surface that is the molding surface 6 Can be adjusted. Also, the melted resin fibers 1b are extruded from the nozzle 3 in a helical shape and are naturally lowered onto the molding surface 6 to form the semi-molten nonwoven fabric 2a entangled with each other. As a result, special equipment for crimping the resin fibers 1b is provided. Becomes unnecessary.

The screw shaft 4 is disposed vertically in the nozzle 3 as shown in FIG. 1A, and the screw shaft 4 'is horizontally arranged at the entrance to the nozzle 3 as shown in FIG. Even if it arrange | positions, the same molten resin fiber 1b can be extruded.

As described above, the semi-molten sheet-like nonwoven fabric 2a formed along the water surface of the molding surface 6 is solidified when cooled as it is, and the sheet-like nonwoven fabric is continuously produced. When the semi-molten sheet-like nonwoven fabric 2a is sent to the molding die 10, the tubular nonwoven fabric 2b is continuously manufactured in the following manner.

The molding die 10 is a trumpet-shaped cylindrical body as shown in FIGS. 2 and 3, and pulls the semi-molten sheet-like nonwoven fabric 2a from the large-diameter side opening 11 to the small-diameter side opening 12. Then, the semi-molten sheet-like nonwoven fabric 2a moves axially along the inner periphery of the conical shape of the mold 10, and the both ends are gradually lifted and rounded as shown in FIG. They are combined into a tube. Since the nonwoven fabric 2b at this time is in a semi-molten state, the butted ends are welded to each other to form a seamless tubular shape. The cylindrical nonwoven fabric 2b is continuously drawn out from the small-diameter side opening 12 of the molding die 10 as a cylindrical body having the same diameter as the opening 12. The cylindrical nonwoven fabric 2b is pulled out from the mold 10 while being guided by the guide rollers 13 and the like, and is naturally cooled or forcibly cooled to produce the long cylindrical nonwoven fabric 2b. In addition, the cylindrical nonwoven fabric 2b drawn out of the molding die 10 can be cut at predetermined lengths by a cutter 14 as necessary to continuously produce short cylindrical nonwoven fabrics 2b.

The tubular nonwoven fabric 2b manufactured as described above
Is a seamless high-quality nonwoven fabric tube, which does not generate ear dust at the time of its production, and allows the resin fibers to be effectively used at a yield of almost 100%, so that the cost of the product can be reduced. In addition, the tubular nonwoven fabric 2b can be easily manufactured regardless of the rigidity thereof, and the low rigidity soft tubular nonwoven fabric 2b is effectively used as a cushioning material or a packing filler because of its excellent elasticity. The cylindrical nonwoven fabric 2b has a hardness that can withstand use under high pressure such as underground or the like, and is effectively used as a drainage pipe for civil engineering, an agricultural and marine material, a filter for biotechnology, and the like.

The outer diameter of the cylindrical nonwoven fabric 2b is
Can be arbitrarily adjusted by the diameter of the small-diameter side opening 12, and the inner diameter and the fiber density of the tubular nonwoven fabric 2b can be arbitrarily adjusted by adjusting the thickness and the fiber density of the sheet nonwoven fabric 2a. In this case, if the inner diameter of the tubular nonwoven fabric 2b is made sufficiently small, a rod-shaped nonwoven fabric can be continuously produced.

In the manufacturing apparatus shown in FIG. 5, the molding surface 6 'on which the molten resin fiber 1b naturally descending from the nozzle 3 is collected is formed by an inclined surface of a slide 15 such as Teflon. When the inclined molding surface 6 ′ is cooled and the molten resin fiber 1 b is naturally lowered from the nozzle 3 directly above, the inclined molding surface 6 ′
The helical molten resin fiber 1b is naturally cooled and further crimped and entangled to form a sheet-like nonwoven fabric 2a, which is slid down the inclined molding surface 6 and drawn into the molding die 10, where the tube is continuously formed. Molded into a shape.

In the case of the manufacturing apparatus shown in FIG.
Even if b has a specific gravity larger than that of water, the sheet-like nonwoven fabric 2a is surely formed. That is, in the case of the manufacturing apparatus shown in FIG. 1, if the molten resin fiber 1b having a specific gravity higher than that of water falls on the molding surface 6 of the water surface, the molten resin fiber 1b sinks in water, so that it is difficult to form the sheet. In the case of the manufacturing apparatus of (1), the fibers can be formed into a sheet shape regardless of the specific gravity of the molten resin fibers 1b.

[0027]

According to the manufacturing method of the first aspect, the molten resin fibers extruded from the nozzle tip by the screw shaft are naturally spirally crimped and entangled by the turning moment applied by the screw shaft. Since it becomes a non-woven fabric fiber aggregate, it is possible to omit special processes and equipment that crimp the resin fiber immediately after production during the consistent manufacturing process from resin fiber production to non-woven fabric production so that it can be easily entangled. In addition, the productivity of nonwoven fabric production can be improved, and a production apparatus that is advantageous in terms of capital investment can be provided.

According to the second aspect of the present invention, the semi-solid sheet-like non-woven fabric continuously manufactured is rolled into a cylindrical shape and rounded into a cylindrical shape, and the rounded ends are welded to each other so that no ear dust is produced. Since it is possible to manufacture a cylindrical nonwoven fabric continuously,
The productivity is improved, and it is possible to produce a low-cost tubular nonwoven fabric using resin fibers at a yield of almost 100%.

The diameter, thickness, and the like of the cylindrical nonwoven fabric are adjusted by adjusting the fineness, density, and descent speed of the molten resin fiber extruded from the nozzle, and the moving speed of the sheet nonwoven fabric between the molding surface and the mold.
There is the convenience that the fiber density can be easily changed, and that a single manufacturing apparatus can manufacture many kinds of cylindrical nonwoven fabrics. Furthermore, the cylindrical nonwoven fabric to be manufactured can be arbitrarily selected from a flexible one to a high rigidity one. In particular, since the rigid nonwoven fabric can be mass-produced continuously, civil engineering materials of the cylindrical nonwoven fabric,
Use of agricultural materials can be expanded.

[Brief description of the drawings]

FIG. 1A is a side view schematically showing an entire manufacturing apparatus according to an embodiment of the present invention, and FIG. 1B is a side sectional view of a modified example of a nozzle.

FIG. 2 is a plan view of a molding die in the manufacturing apparatus of FIG. 1;

FIG. 3 is a perspective view of a molding die in the manufacturing apparatus of FIG. 1;

FIG. 4 is a perspective view showing a forming process of a nonwoven fabric formed into a cylindrical shape by the manufacturing apparatus of FIG. 1;

FIG. 5 is a side view schematically showing an entire manufacturing apparatus as another embodiment of the present invention.

[Explanation of symbols]

 1a Molten resin 1b Molten resin fiber 2a Semi-solid sheet nonwoven fabric 2b Cylindrical nonwoven fabric 3 Nozzle 4 Screw shaft 6 Molding surface (water surface, liquid surface) 6 'Molding surface 7 Water 10 Mold

Claims (4)

[Claims] 1. A thermoplastic molten resin in a nozzle is pressed toward a nozzle tip by a screw shaft, and a plurality of molten resin fibers are spirally extruded from the nozzle tip and naturally descended. A method for producing a nonwoven fabric, comprising forming a sheet-like semi-molten nonwoven fabric by continuously collecting resin particles on a molding surface at a fixed position below a nozzle while entangled with each other. 2. The method for producing a nonwoven fabric according to claim 1, wherein the molding surface is a liquid surface. 3. A cylindrical mold is disposed in a passage in which a sheet-like semi-molten nonwoven fabric formed by descending on the molding surface moves along the molding surface, and is arranged along an inner periphery of the cylindrical mold. While continuously moving the sheet-like semi-molten nonwoven fabric, the both ends of the semi-molten nonwoven fabric are lifted at the inner periphery of the molding die and the both ends are welded to each other, thereby continuously forming the sheet-like semi-molten nonwoven fabric into a cylindrical shape. The method for producing a nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric is formed into a nonwoven fabric. 4. A tubular nonwoven fabric produced by the method of claim 3.