JPH02182960A - Filament nonwoven fabric and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven fabric having good opened state and excellent heat-sealability, etc., in high productivity at a low cost by spinning a specific filament fiber having a sheath-core structure while drawing with an air jet, collecting the fiber in opened state and hot-pressing the collected fibers. CONSTITUTION:A bundle of filament fibers having a sheath-core structure containing (A) a thermoplastic polymer (preferably polyester) as a core component and (B) a polyethylene having a density of >=0.95 as a sheath component is spun at a speed of >=3,000m/min under drawing with an air jet. The blasted fiber bundle is collected in opened state on a moving porous surface in the form of a web and the web is hot-pressed at 50-100 deg.C to obtain the objective fabric having an areal density of 10-300g/m<2> and composed of a filament having a sheath-core structure containing 20-90% of the component B in the cross-section of the fiber. The opening of the blasted fiber bundle is carried out e.g. by making the bundle to collide with a baffle plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuous filament (long fiber) nonwoven fabric made of a specific polyethylene resin and a synthetic resin, and a method for producing the same.

The nonwoven fabric of the present invention has heat sealing properties,
It can be used in a wide range of fields including medical and hygiene fields, general household materials, general industrial materials, and agricultural and civil engineering materials.

[Conventional technology] In recent years, nonwoven fabrics have been expanding into a wide range of fields.

However, there are many different processes and methods for manufacturing nonwoven fabrics.
It cannot be denied that the conditions used and the product characteristics that are limited by these conditions impose limitations on the use of the nonwoven fabric.

For example, in the case of nonwoven fabrics made from staples, short fibers made from various raw materials and shapes can be easily provided, and it can be said that processing into nonwoven fabrics is relatively easy. Moreover, due to the difficulty of the manufacturing process, it is inevitably limited in terms of use.

In addition, the method of making nonwoven fabric from continuous filaments is attracting attention as an economical manufacturing method because it creates a sheet-like product from raw resin in one step, and these methods are increasingly being used in fields that take advantage of their toughness. ing.

On the other hand, when trying to industrially produce nonwoven fabrics made of filaments with unique functionality at low cost, the spunbond process uses a unique manufacturing method that involves a wide variety of steps, so it is difficult to manufacture nonwoven fabrics that are made of filaments and have unique functionality, especially at high speeds under high productivity. This tends to cause problems that affect the basic form of nonwoven fabrics, such as spinnability and filament opening/dispersion properties.

As an invention related to problems that affect the basic form of nonwoven fabrics,
For example, in the case of non-woven fabrics made of core-sheath type fibers, it has been proposed to impart bulkiness by developing crimp and to impart adhesiveness by combining adhesive components, as described in Japanese Patent Publication No. 45-2345. However, although such a method has been put into practical use in the direction of forming a web by carding or the like as short fibers, no product has been found that is sufficient to exhibit the desired characteristics in spunbond nonwoven fabrics made of filaments.

Recently, in order to improve adhesive performance, fibers using specific polyethylene as a sheath component have been published in Japanese Patent Application Laid-Open No. 63-9272.
However, the invention proposed in this publication requires the use of a specific polyethylene such as octene copolymer, and moreover, it is difficult to put it to practical use in the form of short fibers. As proposed, problems remain in practical application of long fiber nonwoven fabrics due to low productivity and low quality due to the aforementioned low spinnability and low opening properties.

In particular, for nonwoven fabrics whose purpose is to provide heat sealing properties, it is important that the constituent fibers of the nonwoven fabric be sufficiently spread into individual fibers without agglomeration in order to obtain good heat sealability. become.

[Problems to be Solved and Attempted by the Invention] In view of the above-mentioned points, an object of the present invention is to produce a continuous filament nonwoven fabric that is economically inexpensive and has good heat sealing properties under high productivity. In particular, long-fiber nonwoven fabrics whose continuous filaments are well spread into individual filaments without agglomeration, exhibiting excellent uniformity, and thereby possessing good heat-sealing properties. We are trying to provide a manufacturing method.

[Means for Solving the Problems] The long-fiber nonwoven fabric of the present invention that achieves the above objects has a thermoplastic polymer as a core component, a polyethylene having a density of 0.95 or more as a sheath component, and fiber breaks perpendicular to the fiber axis. A long-fiber nonwoven fabric characterized in that the constituent filaments are core-sheath structure filaments in which the proportion of sheath component polyethylene in the area is 20% or more and 90% or less, and has a basis weight of Log/m2 or more and 300g/m2 or less. .

In addition, the method for producing a long fiber nonwoven fabric of the present invention that achieves the above-mentioned object uses a thermoplastic polymer core component, and has a density of 0.9.
A bundle of filament fibers with a core-sheath structure made of polyethylene of 5 or more as a sheath component is attached to a jet air flow at a rate of 300 per minute.
The spun filament fiber bundles are spun while being drafted at a speed of 0 m or more, and the spun filament fiber bundles are collected in the form of a web on a porous moving surface in an opened state. This is a method for producing a long fiber nonwoven fabric, which is characterized by carrying out a heat and pressure treatment at °C.

[Operation] The present invention will be explained in more detail below based on the drawings and the like.

FIG. 1 is a process outline diagram showing one embodiment of the method for manufacturing a long fiber nonwoven fabric of the present invention, in which 1 and 2 are extruder extruders, and both extruders 1.
The molten polymer from each extruder is filtered through the spin block 3 connected to the spin block 2 and the filter/die pack 4 therein, and then discharged from the die pores in the form of filament fibers.

Preferably, at least 20 discharged threads 5 are discharged in this way, traveling in the atmosphere, and being discharged from 20 cm below the nozzle at a distance of 200 cm.
The air is sucked into an air aspirator 6 installed at a position below cm and is ejected. Then, the ejected filament group 7 is caused to collide with the baffle plate 8, thereby promoting direction change of the jet flow 10 and improvement in fiber opening and spreading properties. The jet flow is preferably carried by a wire mesh conveyor 11 having a suction duct 12 installed at a position of 10 cm to 100 cm below the baffle plate.
The material is collected on the surface to a desired basis weight, and downstream thereof, it is pressed and wound up by a heated and pressurized calender roll 9.

FIG. 2 and FIG. 3 are cross-sectional views showing detailed aspects of the discharge part mouthpiece, each of which is composed of an upper plate 13 and a lower plate 14, and the core component is passed through a pore 15 or a pipe 16 bored in the upper plate 13. The melt is forced out under pressure and brought into contact with the sheath component passageway 17 bored in the lower plate. Here, as shown in FIG. 2, in one embodiment, there is a method in which a gap 18 is provided so that the meeting part is directly covered from the lateral direction with respect to the flow direction of the melt from the upper plate; In another embodiment as shown in the figure, a method is adopted in which a flow is created in the same direction as the flow direction of the melt from the upper plate 13 to form a covering double pipe 19. As will be described later, the former structure shown in FIG. 2 is particularly effective in order to properly eccentricize and eliminate bending on the discharge surface of the nozzle.

FIG. 4 shows an example of a cross section of a fiber used as a constituent fiber in the present invention. In either cross section, polyethylene with a density of 0.95 or more is used as a coating component. The polyethylene used in the present invention refers to an ethylene polymer having fiber-forming ability, and may include various copolymers or a mixture of a part thereof, and other organic synthetic polymers to the extent that the basic properties of polyethylene are not impaired. They may be combined or mixed with inorganic substances. Noriharu's resin, which is generally referred to as high-density polyethylene, can be suitably used.

Figures 6A and 6B are micrographs (
30 times), and Figure A shows the case where the polyethylene of the present invention with a density of 0.95 or more is used, and the appearance that the individual fibers are well spread and has excellent coating performance is obvious at a glance. . - On the other hand, Figure B shows the case where polyethylene with a density of 0.94 is used, and the individual fibers are in a bundled state, and even if such a material is made into a non-woven sheet, it will not have good covering properties. It is extremely impractical due to its poor physical properties.

In the present invention, organic synthetic polymers having fiber-forming ability other than polyethylene are used for the core component, but the melting point of these polymers is preferably at least 20°C higher than the melting point of the polymer used for the sheath component. It is important that the temperature is high; if this condition is not met, the nonwoven fabric will lack heat sealing performance in the practical stage, which is not preferable. Polyester is preferably used as such a core component. In other words, polyester is thin as a core component, and spinning performance is not substantially impaired even when spun eccentrically as described below, and the surface crystallization of the sheath component is promoted during spinning. This significantly contributes to improving the opening performance.

The shape of the fiber cross section of the core component and sheath component can be circular or non-circular, as shown in Figure 4 A-J, but regardless of which cross section it has, the area ratio occupied by the sheath component is 20%.
It is necessary that the ratio be 90% or less, and if it is out of this range, it is not preferable because it not only becomes difficult to manufacture a nonwoven fabric, but also the heat sealing performance is significantly inhibited.

In particular, it is an interesting fact that the practical heat sealing performance is superior when the sheath coating structure is preferably non-uniform rather than uniform. As these means, it is preferable to arrange the core component eccentrically, or to have a cross-sectional structure in which the sheath component has a different thickness. In order to create such an eccentric structure, for example, use a cap with the shape shown in Figure 2,
It is preferable to shift the centers of the upper and lower pores, and this may be due to the viscoelastic properties of the polyethylene liquid flowing through the gap 18.
The discharged strips are not bent and can withstand high-speed spinning.

The yarn thus discharged is tension-spun with a fluid stream, preferably at least 20 filaments together, at a speed of 3000 m/min or more. According to the findings of the present inventors, by this method, the fineness of single fibers can be reduced to 0.
Good web formation is possible within the range of 1 denier to 10 denier. Improving productivity is a very important requirement in the production of spunbond nonwoven fabrics, but by satisfying the requirements of the method of the present invention, even if a low melting point component is placed on the outside and a high melting point component is used in the core, The spun filaments do not become bundled and can form a web in a very well-opened state.

FIG. 5 is a schematic diagram showing an example of the structure of the nonwoven fabric of the present invention, in which portions 22 that exist discretely over the entire surface of the sheet are crushed and bonded, and unrestricted portions in which fibers are randomly arranged. It consists of 23. The area of the portion 22 is preferably in the range of 0.2 mm2 to 10 mm2 from the viewpoint of not impairing drapability, and in order to ensure heat sealing performance, it is more preferable that the area does not exceed 50% of the total area of the sheet. It is preferable that the restraining portions 22 are scattered within a range not exceeding 15%. The reason for this is that the sheath component of the already pressed portion is deformed and its contribution to heat sealing performance is reduced.

The nonwoven fabric of the present invention has a basis weight of Log/m2 to 300g/
When formed into a sheet with a thickness of It is suitable for fields where it is processed and used.

The nonwoven fabric of the present invention can be easily heat-sealed, and generally, sealing can be achieved by simply pressing it between a heating head at 150° C. and a pressure of 2 kg/a for about 1 to 2 seconds. In addition to being used to take advantage of these practical properties, the present invention is an effective material in fields where the unique luster, smoothness, electrical properties, and other physical and chemical properties of the sheath component are utilized.

[Example] Hereinafter, the present invention will be specifically explained using examples.

Example Sheath component: Polyethylene with a density of 0.950 and a melt index of 30 g/10 min as measured by JIS K6760 (Ace Polyethylene HD manufactured by Showa Denko K.K.)
The fibers were jetted using the apparatus shown in FIG. 1 using polyethylene terephthalate having an intrinsic viscosity of 0.62 as measured in an orthochlorophenol solution as a core component.

The cap used at this time had the structure shown in Figure 2, with the upper plate pores being circular with a diameter of 0.3 mm, and the lower plate pores having a diameter of 0.2 mm.
The wide part of the circle is 1mm.

The narrow part is 0.5 mm. The number of pores in the lower plate was 66 per ferrule. The sheath component was extruded at 180°C and passed through a metering pump to a spin block heated to 280°C, and one core component was extruded at a temperature of 280°C and fed to the same spin block. The metering pump dispenses 33g of both the sheath and core components per minute (core/sheath ratio 50:50).
Supplied for individual caps.

An air aspirator was installed at a position t00 cm below the mouthpiece. The structure of the aspirator is that the thread suction port has a diameter of 8 mm.
The compressed air jet annular slit has an outer diameter of 8.1 mm, and a pipe with an inner diameter of 10 mm and a length of 50 cm is connected below the slit. A collision plate was placed at the tip of the pipe at a distance of 3 mm and at an obtuse angle of 30 degrees with the axis of the pipe. The collision plate has a structure in which the fibers ejected from the pipe come into contact with each other for 1 cm and are then released into the atmosphere. With these devices, compressed air with a pressure of 2.5 kg/cTiGK can be
The yarn was supplied in an ON bottle, and the yarn discharged from the nozzle was suctioned into an aspirator and ejected from the outlet thereof.

The obtained filament fiber had a fineness of 2.25 denier,
At a spinning speed of 4000 m/min, the strength and heat shrinkage properties were practically satisfactory.

In particular, the obtained fiber mass has excellent spreadability, which is the most important requirement for forming a nonwoven fabric, as shown in FIG. 6A.

Furthermore, the fiber group ejected under the above conditions is placed below the collision plate 4.
It was collected on a moving wire mesh at a position of 0 cm. At this time, a suction fan was installed below the collection position to ensure that there was no disturbance in the formation of the web on the wire mesh. The web on the running wire mesh is heated at the same temperature as a smooth calender roll heated to 110°C, and a pressure of 15 kg/cm is applied between embossing rolls whose surfaces are engraved with circular planar protrusions arranged at 5 mm intervals, each having a diameter of 1 mm. They were sandwiched and joined at cm2.

The obtained sheet had an elegant luster, a smooth surface and high flexibility, and the single fibers were very well opened and evenly distributed.

When the sheet was cut into 5 cm square pieces and the weight of each piece was measured, the average basis weight determined from the data of each section was 50 g/rr? , the coefficient of variation was 4%.

The sheet collected as described above is JISZ-170
A heat seal test was conducted using method 7. Here, the sealing temperature was 150° C., the pressure was 1 kgf/ad, and the pressurization time was 3 seconds. The obtained value was 2.52 kg/15 mm, which was very suitable for various packaging materials.

Comparative Example 1 The same equipment and conditions as in the above example were used, and polyethylene (Shorex, manufactured by Showa Denko K.K.) having a density of 0.916 and a melt index of 23 g/10 minutes was used as the sheath component. As shown in FIG. 6B, the obtained fiber mass had agglomerated single fibers and had a large number of unopened fibers. The calendered web taken from this material had noticeable gaps between fibers, lacked coverage, was extremely non-uniform, and had a basis weight variation rate of more than 20% by the above-mentioned method.

The results of measuring the sheet taken in this comparative example under the same conditions are 1. 2 kg/15 mm, and the sealing surface was easily damaged, making it obsolete for practical use.

[Effects of the Invention] As explained above, according to the present invention, a filament nonwoven fabric with excellent uniformity in which the single fibers are well opened can be obtained.

Such non-woven fabrics can be heat-sealed without using any means such as lamination or coating, and it is extremely significant industrially that a non-woven fabric with such good heat-sealing properties can be obtained by such simple means. It is. Since the nonwoven fabric maintains simple heat-sealing properties, it reduces molding labor in practical use, and is a clean material that is extremely effective as a living and industrial material.

[Brief explanation of the drawing]

FIG. 1 is a process outline diagram showing one embodiment of the method for producing a long fiber nonwoven fabric of the present invention. FIGS. 2 and 3 are schematic cross-sectional views each showing an aspect of the discharge part nozzle in the method of the aspect shown in FIG. 1. FIGS. 4A to 4J are schematic cross-sectional views showing an example of the cross-sectional structure of the constituent fibers of the long fiber nonwoven fabric of the present invention. FIG. 5 is a schematic diagram showing an example of the adhesive structure of the nonwoven fabric of the present invention. 6A and 6B are collected on a wire mesh conveyor, and FIG. 6B is outside the scope of the present invention. 1.2: Extruder extruder 3 Nispin block 4: Filter/mouth pack 23: Discharge thread 6: Air aspirator - discharge filament group baffle plate 9: Calendar roll jet
11: Wire mesh conveyor suction duct 13: Upper plate lower plate 15: Pore pipe 17: Passage gap 19: Double pipe discharge hole Partial fibers that existed discretely over the entire surface of the sheet and were crushed and glued were randomly arranged. Unrestricted partial patent application Daito Co., Ltd. Figure 4 Figure 1! District 2, Figure 6, Figure A, Figure 6, B

Claims (6)

[Claims] (1) The core component is a thermoplastic polymer, the sheath component is polyethylene with a density of 0.95 or more, and the ratio of the polyethylene sheath component to the cross-sectional area of the fiber perpendicular to the fiber axis is 20% or more and 90% or less. Structural filaments are used as constituent filaments, and the basis weight is 10 g/m^2 or more and 300 g.
/m^2 or less. (2) The long fiber nonwoven fabric according to claim (1), wherein the cross-sectional structure of the core component in the fiber cross section perpendicular to the fiber axis is non-circular. (3) The long fiber nonwoven fabric according to claim (1) or (2), wherein the cross-sectional outer peripheral shape of the sheath component polyethylene in the fiber cross section perpendicular to the fiber axis is non-circular. (4) The long fiber nonwoven fabric according to claim (1), (2) or (3), characterized in that the fineness of the constituent filaments is 0.1 denier or more and 10 denier or less . (5) Emboss processing is applied to substantially the entire surface of the nonwoven fabric in a dot-like emboss pattern, and the area of each dot of the emboss pattern is 0.2 mm^2 or more and 10 m.
m^2 or less, and the area ratio of the dot embossed portion to the total area of the nonwoven fabric is 1% or more and 30% or less,
The long fiber nonwoven fabric according to item (3) or item (4). (6) A bundle of core-sheath filament fibers having a thermoplastic polymer core component and polyethylene with a density of 0.95 or higher as a sheath component is spun while being drawn at a speed of 3000 m/min or higher while being accompanied by a jet air flow. Further, the sprayed filament fiber bundle is spread out and collected in the form of a web on a porous moving surface, and the collected web is heated at a temperature of 50° C. or more to 110° C.
A method for producing a long-fiber nonwoven fabric characterized by heat and pressure treatment at °C.