JP2586126B2 - Long-fiber nonwoven fabric and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous filament (long fiber) nonwoven fabric having a specific structure, comprising a specific polyethylene resin and a synthetic resin, and a method for producing the same.

The nonwoven fabric of the present invention has good heat sealing properties, and is effectively used in a wide range of fields such as medical hygiene, general living materials, agricultural civil engineering materials, and in particular, articles used by heat sealing.

[Related Art] In recent years, nonwoven fabrics have entered a wide range of fields. However, it is undeniable that various and various processes and conditions are used in the method for producing the nonwoven fabric, and that the product characteristics limited by the processes and conditions impose restrictions on utilization.

For example, in the case of staple nonwoven fabric, various raw materials and
Short fibers with a changed shape can be provided easily, and it can be said that processing into nonwoven fabric is relatively easy with general-purpose fibers,
Since it is a short fiber, there are some restrictions on practical mechanical properties such as toughness and durability of the product.

In addition, special fibers cannot be easily obtained, and it is generally difficult to provide unique functions and specific properties because of the high difficulty in the steps of opening and forming a web.

On the other hand, the method of making a nonwoven fabric from continuous filaments is not only an economical manufacturing method because a sheet-like material is made at once from the raw material resin, but also eliminates the difficulty of processing a single fiber, so it can be easily thickened. It has the advantage that it can be made from thin to non-woven fabrics, and efforts have been focused on the development of tough nonwoven fabrics and nonwoven fabrics with special functionality.

In order to industrially produce a nonwoven fabric having such a specific function consisting of such filaments at a low cost, the spunbonding process uses a unique production means over a wide range of processes, and therefore, particularly under high productivity. It is easy to cause disadvantageous problems that affect the basic form of the nonwoven fabric, such as high-speed spinnability and filament opening / dispersibility.

As an invention relating to a problem affecting the basic form of the nonwoven fabric, for example, in a nonwoven fabric made of bimetallic conjugate fiber, for example, as described in JP-B No. 45-2345, imparting bulkiness by expressing crimping, adhesive component Although it has been proposed to provide adhesive performance by composite, such a method is practically used in a method of forming a web by carding or the like as short fibers, but in a spunbond nonwoven fabric composed of filaments, In general, fibers tend to be bundled and tend to develop shrinkage in the coil state, so they have the desired characteristics,
And there are no products that are practical enough.

Further, recently, for the purpose of improving the adhesion performance, a fiber using a specific polyethylene has been proposed in JP-A-63-92723, but in the invention proposed in the publication,
Although a specific polyethylene such as octene copolymer must be used, and more specifically, practical application in a core-sheath conjugate fiber state has been proposed, such a core-sheath conjugate fiber has a heat sealing performance. It is necessary to increase the thickness of the sheath component in order to increase the ratio, the ratio of the core component that governs the main performance as a nonwoven fabric is limited, and as a result, the spinnability is impaired, and the fiber characteristics and nonwoven fabric characteristics have disadvantages. There was a problem of inviting.

Further, as a production technique of split-fiber composite nonwoven fabric, JP-A-60-75658 discloses that a water-swellable polymer is used as a boundary component in order to split a fiber with a water jet stream, and thus the independent component is used. It is disclosed that the splitting is promoted.

However, these methods require selection of relatively expensive materials, and are undesirable in some applications such as drying after treatment, accompanying quality control, and practically possessing water absorption. There is.

In particular, in the case of a nonwoven fabric intended to provide heat sealing properties, it is important that the nonwoven fabric constituent fibers be sufficiently opened to individual fibers without agglomeration in order to obtain good heat sealing properties. become.

[Problems to be Solved by the Invention] In view of the above points, an object of the present invention is to exhibit a remarkable effect, particularly when used as a heat sealing material, and to provide a high productivity at a low cost economically. To provide a continuous filament (filament) nonwoven fabric that can be manufactured under
In particular, the split-type composite continuous filament fibers are well spread into individual filaments without agglomeration, are very uniform, have good softness, and have good heat sealing properties. And a method for producing the same.

Another object of the present invention is a nonwoven fabric which is made of splittable composite filament fibers made of a hydrophobic polymer and can be split easily by a water jet flow, and which is flexible, tough, rich in uniformity, and heat-sealing. An object of the present invention is to provide a nonwoven fabric having the above-mentioned structure and a simple production technique thereof.

[Means for Solving the Problems] The long-fiber nonwoven fabric of the present invention that achieves the above object has a fiber-forming thermoplastic polymer component as a boundary component and a density of 0.95.
Long fibers having a split-fiber composite filament structure containing the above polyethylene component as an independent component, and comprising at least 20% or more and 90% or less of the total cross-sectional area of the polyethylene component. It is a non-woven fabric, and the constituent filaments are joined to each other by the polyethylene component, and the basis weight is 10 g / m ² to 300 g.
/ m ² or less, embossing to be a dot pattern is performed over the entire surface of the nonwoven fabric, and the area of one dot of the emboss pattern is 0.2 mm ² or more and 10 mm ² or less, and A long-fiber nonwoven fabric characterized in that the ratio of the dot embossed portion to the entire area of the nonwoven fabric does not exceed 50%.

Further, the method for producing a nonwoven fabric according to the present invention is characterized in that a composite filament fiber exhibiting a split composite structure having a fiber-forming thermoplastic polymer component as a boundary component and a polyethylene component having a density of 0.95 or more as an independent component accompanies a jet air flow. 3000m per minute
Spinning while pulling at the above speed, furthermore, after the spun filament fiber bundle hits the collision plate and is opened, the injection filament group is collected on a porous moving surface, and further,
50 ° C to 120 ° C for collected filaments
It is characterized in that it is subjected to a heat pressurization treatment at a temperature of ° C.

[Operation] Further details will be described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing the steps of an embodiment of the method for producing a long-fiber nonwoven fabric according to the present invention, wherein reference numerals 1 and 2 denote extruder extruders.
The polymer melted from each of the extruders is filtered through a spin block 3 connected to the filter and a filter / cap pack 4 therein, and then discharged from the cap pores into filament fibers.

The preferably at least 20 discharged yarns 5 discharged in this manner travel in the atmosphere and are sucked and jetted by an air aspirator 6 installed at a position 20 cm to 200 cm below the base. Then, the jet filament group 7 is caused to collide with the baffle plate 8, and the change of the direction of the jet 10, the improvement of the spreadability, the improvement of the spreadability, and the like are promoted. The jet preferably has a suction duct 12 located 10 cm to 100 cm below the baffle 8.
The web 16 is collected on a wire mesh conveyor 11 having a desired basis weight so as to form a web having a desired basis weight, and is heated and wound by a heated and pressurized calender roll 9 downstream thereof.

In another embodiment, the nonwoven fabric 18 is guided directly from the calender roll 9 onto the conveyor wire mesh 17, dive under the water jet 19, entangles with splitting, and is wound up via the squeezing roller 21 and the drying roller 22. Winding machine 23.

FIG. 2 is a partial cross-sectional view showing a detailed mode of the discharge unit base, and FIG. 3 is a view showing one mode of a hole formed in the upper plate. The fiber-forming thermoplastic polymer component is caused to flow under pressure from a non-circular hole 26 having, for example, a “+” shape corresponding to the boundary pattern of the fiber cross section formed in the upper plate. The lower plate is provided with a projection 31 having a cutout portion 30 corresponding to the concave portion 29 of the non-circular hole of the upper plate, which is connected to the passage 27 of polyethylene, and the discharge member from the non-circular hole of the upper plate and the cutout portion. Is discharged from the mouthpiece through a hole 32 formed in the lower plate 25 and a subsequent fine hole 33.

FIG. 4 shows an example of the cross-sectional structure of the fiber used in the present invention. However, the present invention is not limited to the embodiment shown in FIG. And all having the structure of

That is, in any cross section, a thermoplastic polymer component other than an ethylene polymer having a fiber-forming ability is used as a boundary component 34, and a polyethylene component having a density of 0.95 or more is an independent component.
It has a structure of 35. The boundary component referred to here has a role of arranging polyethylene components in a plurality of discrete states, and a plurality of polyethylene components may be used without being limited to one continuous shape. However, it is important that part of the fiber is exposed on the outer peripheral surface of the cross section.
Fibers having a cross-section buried in the entire periphery and buried with a polyethylene component do not exhibit the effects of the present invention well. In addition, the polyethylene component referred to here refers to an ethylene polymer having a fibrous property, and if the density is 0.95 or more, various polymers or a mixture of some of them, and the basic properties of polyethylene Other organic synthetic polymers or inorganic substances may be mixed to the extent that they are not impaired. Preferably, a resin in the category referred to as linear high-density polyethylene exerts special effects in multiple aspects such as composite performance, spinning performance, fabric production performance, and product practical characteristics. In this case, it is important that the temperature of the polyethylene component discharged from the die is not less than its melting point and at least 20 ° C or more, preferably under conditions from about 50 ° C to about 140 ° C higher than the melting point of the polymer. This is preferable because the spinning instability due to bending or the like can be improved upon ejection from the die. In addition, the desired effects of the present invention can be exerted under spinning conditions described later.

If the temperature is high and the spinning stability for a long time is impaired, known antioxidants and reduction by adding a thermal decomposition inhibitor can be eliminated, and these additions should be considered. Even if those additives are included,
It is included in the scope of the present invention.

As the fiber-forming thermoplastic polymer as the boundary component, any polymer that can be melt-spun other than polyethylene can be used. These polymers include polyesters such as polyethylene terephthalate, polyamides such as nylon 6, polyolefins such as polypropylene, sulfur-containing polymers such as polyphenylene sulfide, various thermoplastic elastomers, various other known polymers and copolymers. included. It is important that the melting point of these polymers is at least 20 ° C. higher than the melting point of the polyethylene component, and if this condition is not satisfied, the heat sealing performance in the practical stage of nonwoven fabric is somewhat inferior.
Among these polymers, especially when polyethylene terephthalate or a copolymer thereof is used, the spinning performance is improved, the surface crystallization during the spinning of polyethylene is promoted, and this greatly contributes to the improvement of the fiber opening performance. It is very suitable in that it has excellent heat sealing properties, and furthermore, the boundary component and the independent component are divided by the treatment of the water jet stream, that is, the splitting effect is large.

FIGS. 6A and 6B are running electron microscope photographs (30 ×) of a nonwoven fabric before treatment with a water jet flow. FIG. A shows that when the polyethylene of the present invention having a density of 0.95 or more is used as an independent component, the fibers are well opened to individual fibers and have excellent coating performance. On the other hand, FIG. B shows the case where polyethylene having a density of 0.94 is used as an independent component, in which the fibers are in a bundled state. It is also clear from the damaged state. Of course, the physical properties of the nonwoven fabric are impractical and inferior.

The shape of the polyethylene component and the other component in the fiber cross section may be circular or non-circular, as shown in FIGS. 4A to 4D. The ratio should be between 20% and 90%, more preferably between 50% and 90%,
It is important that the other boundary polymer component is exposed on a part of the outer periphery of the cross section. Within this range, the filament opening of the constituent filament fiber bundles is excellent, spinning troubles such as thread breakage can be reduced or eliminated, and heat sealing performance can be improved more than expected. Furthermore, as described above, the splitting and confounding effects due to the water flow can be remarkably obtained.

The yarn discharged from the die is preferably at least
Twenty filaments are drawn and spun by a fluid flow so as to have a speed of 3000 m / min or more.According to the present invention, a web can be satisfactorily formed in a filament fineness not exceeding 0.1 denier to 10 denier. . It is a great industrial contribution that a web can be formed in a well-spread state without being bundled by satisfying the requirements of the present invention.

FIG. 5 is a schematic view showing an example of the bonded structure of the nonwoven fabric of the present invention, in which a portion 36 which is discretely crushed and bonded over the entire surface of the sheet and an unconstrained state in which the fibers are randomly arranged are shown. Consisting of part 37. The area of the portion 36 is important in that the range of 0.2 mm ² to 10 mm ² does not impair drapability, and in order to ensure good heat sealing performance, the area does not exceed 50% with respect to the entire area of the sheet, More preferably
It is preferable that the constrained portions 36 be scattered within a range not exceeding 15%. The reason for this is that if there are many parts that have already been pressed,
This is because the fiber structure is deformed, the splittable conjugate fibers are crushed, and the respective components are mixed with each other and flattened, so that the contribution to the heat sealing performance is reduced.

In particular, the basis weight of the non-woven fabric is
It is necessary to be in the range of 10 g / m ² to 300 g / m ² . In the nonwoven fabric having a basis weight in such a range, a desired effect can generally be sufficiently exhibited, and in a nonwoven fabric having a basis weight less than the above range, bonding with polyethylene having practical strength cannot be achieved, or in a nonwoven fabric having a basis weight exceeding the above range, There is a disadvantage that it is difficult to obtain a locally constrained portion, and the whole surface tends to be rough and rough with a hard feel. Further, a nonwoven fabric having a high basis weight cannot well exhibit the simple heat sealing performance characteristic of the present invention.

In another embodiment of the present invention, the collected web is subjected to calendering if necessary, and then splitting and entanglement is performed by a water jet, thereby providing a novel flexible and heat-sealing property. A non-woven fabric can be provided. A water jet is a jet having a columnar flow having a diameter of about 0.05 mm to about 1 mm, which is jetted in a number of rows. Usually, a pressure of 5 to 15 is applied through a slightly larger hole than desired.
It is easily obtained by squirting at 0 kg / cm ² . In the present invention, the treatment is preferably performed at 30 to 100 kg / cm ² from the viewpoint of obtaining a sufficient split fiber economically and not impairing the uniformity of the nonwoven fabric. In this case, it is preferable that the water jetting holes have a diameter of about 0.1 mm to 0.25 mm, since the jetting power can disperse and entangle in a well-balanced manner without disturbing the uniformity of the nonwoven fabric. The term "entanglement" as used herein means that the constituent fibers are randomly entangled three-dimensionally and contribute to the stabilization of the form without using an external means such as an adhesive or a hot press. When processing a web under a multi-jet stream, a locus is drawn on the nonwoven fabric according to the arrangement of the water ejection holes. When the web to be processed is run with the ejection holes fixed, a trajectory that is a line at regular intervals is obtained. This is particularly strong in the direction in which it is pulled in the running direction of the nonwoven fabric. In addition, when the interval between the streaks is widened, it is possible to provide a nonwoven fabric which is not only rich in flexibility and bulkiness but also has a non-entangled portion with remarkably excellent heat sealability.

Further, when the water injection hole is swung right and left and processed through the web so as to be orthogonal to the swing direction, the confounding locus draws a curve and contributes to the equalization of the physical properties of the nonwoven fabric in the vertical and horizontal directions. By increasing the swing cycle and swing width, it is possible to make the entangled portion exist over almost the entire nonwoven fabric,
This provides a practically valuable product that does not fray the surface fiber due to friction and has a smooth surface and flexibility. Furthermore, these nonwovens have a high degree of moldability.
For example, a porous film can be easily obtained by calendering the nonwoven fabric at 150 ° C. Further, when a heat treatment is performed while being sandwiched between a mold having a desired shape, a tough molded product can be obtained without any obstacle such as shrinkage. In the case where the heat treatment is performed under non-restraint, the non-shrinkage can be achieved without shrinkage by improving the non-woven fabric before the treatment to an appropriate hardness.

The nonwoven fabric of the present invention is used to process sheets in the fields where conventional nonwoven fabrics are used, as well as packaging and covering materials, filters, wipers, sanitary / medical materials, various molding materials, and other fields. It is suitable for the field where the reason is.

The nonwoven fabric of the present invention can be easily heat-sealed, for example,
Sealing can be performed only by pressing for about 1 to 2 seconds between heating heads at 150 ° C. and a pressure of 2 kg / cm ² .

In addition, the fact that the structure of the present invention has a better heat sealing property and a combination of the above-mentioned effects than conventional nonwoven fabrics can be said to have extremely high industrial value.

The nonwoven fabric of the present invention is a material that is effective not only for utilization utilizing these heat sealing properties but also for fields utilizing electrical characteristics and other physical and chemical characteristics.

[Examples] Hereinafter, the present invention will be described with reference to examples.

Example 1 As an independent component, polyethylene (Acepolyethylene HD manufactured by Showa Denko KK) having a density of 0.950 and a melt index of 30 g / 10 min as measured by JIS-K6760, and an intrinsic viscosity of 0.62 measured with an orthochlorophenol solution as a boundary component. Using polyethylene terephthalate, spinning of split-split composite filament fibers having the fiber cross section of FIG. 4A was performed by the apparatus shown in FIG. The base used at this time has the structure as shown in FIG. 2, and the upper plate hole has a width of 0.1 m.
m, 1.0mm long slits are drilled in a + shape, the inner diameter of the protrusion at the top of the lower plate is 1mm, the outer diameter is 2mm, the height is 1mm, the height of the notch is 0.5mm, the width is 0.5mm And is arranged so as to fit into the gap between the slit of the upper plate and the hole. The lower plate pore has a diameter of 0.2 mm and 66 holes per hole. The polyethylene component is melt-extruded at 180 ° C. and fed to a spin block heated to 280 ° C. via a metering pump, while the polyester component is extruded at a temperature of 280 ° C. and fed to the same spin block. Both components from the metering pump every minute
33 g was supplied to one base. An air aspirator was installed at a position 100 cm below the base.

The aspirator has a structure in which the diameter of the yarn suction port is 8 mm, the outer diameter of the annular slit for jetting compressed air is 8.1 mm, and a pipe with an inner diameter of 10 mm and a length of 50 cm is connected below. At a distance of 3 mm from the tip of the pipe, an impact plate is arranged at an obtuse angle of 30 degrees with the axis of the pipe. The impact plate has a structure in which the fibers ejected from the pipe make a 1 cm contact and then are released into the atmosphere. 2.5 kg / cm ² G with these devices
Was supplied at 800 Nl / min, and the discharged yarn from the nozzle was sucked into an aspirator and jetted from the outlet.

The resulting fiber has a fineness of 2.25 denier and a spinning speed of 4000 m /
The area ratio of polyethylene to the total cross-sectional area of the filament in min was 55%, and a product having the cross section shown in FIG. 4A and having excellent strength characteristics and heat shrinkage characteristics was obtained. The fibers ejected under these conditions were collected on a wire mesh moving 40 cm below the impact plate. At this time, a suction fan was installed below the collecting position so that the formation of the web on the wire mesh was not disturbed. The web on the running wire mesh was sandwiched at a pressure of 15 kg / cm between embossed rolls having the same temperature as that of a smooth calender roll heated to 110 ° C. and engraved by arranging engraved rolls having a diameter of 1 mm and circular flat surfaces arranged at intervals of 5 mm. The obtained sheet had an elegant luster, had a smooth surface, was rich in flexibility, and had a single fiber that was well opened and uniformly dispersed.

In addition, as shown in FIG. 6A, the obtained non-woven fabric was obtained by opening individual filaments well and obtaining a practical one having a high uniformity.

This nonwoven fabric was cut into 2.5 cm squares, and the weight of each was measured. The average basis weight calculated from the data of individual sections is 50
g / m ² , the coefficient of variation was 6%.

Comparative Example 1 Using exactly the same apparatus and conditions as in Example 1 above, polyethylene (Shiolex manufactured by Showa Denko KK) was used as an independent component with a density of 0.916 and a melt index of 23 g / 10 minutes.

The obtained nonwoven fabric has a large amount of unspread fibers in which single fibers are aggregated as shown in FIG. 6B, lacks coverage in which gaps between fibers are conspicuous, is extremely uneven, and has a basis weight variation of 20%. %
Was beyond.

Example 2 The sheet collected in Example 1 was subjected to a heat sealing test according to the method of JIS Z-1707. Where the seal temperature is 150
C., the pressure was 1 kgf / cm ² , and the pressurization time was 3 seconds. The obtained value was 3.12 kg / 15 mm, which was suitable for various packaging materials. The result obtained by measuring the sheet taken in the comparative example under the same conditions was 0.9 kg / 15 mm, and the result was inferior in practical use because the sealing surface was easily damaged.

Example 3 The web obtained from the calender roller obtained in Example 1 was split and entangled by a water jet. The diameter of the jet holes was 0.15 mm, and the interval between the holes was changed from 0.5 mm to 5.0 mm in 0.5 mm increments.

The injection pressure was 80 kg / cm ² , and a web placed on an 80 mesh wire mesh was supplied 5 cm below the ejection hole. The processing speed was 1 m per minute. The processed web was passed through a squeezing roller and then through a low-temperature suction drum dryer.

The obtained nonwoven fabric has a vertical entanglement trajectory corresponding to the interval between the jet holes, and the fibers of the entangled portion are split so that the cross-sectional shape of the original composite fiber is not stopped, and each split is performed. The ultrafine fibers were well entangled, and the fibers were entangled to such an extent that removal of the fibers from the entangled portion was impossible. All of them exhibited values exceeding 2.5 kg / 15 mm in the same heat sealing performance test as in Example 2, and the strength was improved as the spacing between the muscles was increased.

Example 4 Using a jet having a water jet hole interval of 0.5 mm in Example 3, water was jetted under a pressure of 80 kg / cm ² while oscillating the jet at a vibration width of 1.0 mm and a cycle of 20 cycles / sec. Min 1mm
Processed the web at the speed of

The dried non-woven fabric is divided into ultra-fine fibers in a state where the cross-sectional shape of the original conjugate fiber does not remain over the entire surface, entangled and entangled with each other, soft, moderately bulky and drapable, dense and smooth A nonwoven fabric was obtained.
The heat sealing property test of Example 2 showed a value of 1.6 kg / 15 mm, which was easily damaged, but exhibited excellent performance in packaging materials, filters, molding materials, medical materials, and sanitary materials.

[Effects of the Invention] As described above, according to the present invention, a filament nonwoven fabric which is made of a fiber in which a single fiber is well opened and which is made extremely fine by splitting, and which is rich in coverage and uniformity is obtained. Can be

Such a nonwoven fabric is a flexible nonwoven fabric that can be heat-sealed by simple means without sacrificing flexibility and bulkiness regardless of means such as lamination or coating.
It is extremely significant in industry.

In addition, the nonwoven fabric retains strong processing performance by a simple heat seal, so that it is possible to reduce molding time in practical use and is extremely effective as a clean material for daily life and industrial materials.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing one embodiment of the method for producing a long-fiber nonwoven fabric of the present invention. FIG. 2 is a partial cross-sectional view showing a detailed mode of the discharge unit base, and FIG. 3 shows one mode of a hole formed in the upper plate. 4A to 4D show an example of a cross-sectional structure of a fiber used in the present invention. FIG. 5 is a schematic view showing an example of the bonding structure of the nonwoven fabric of the present invention. FIGS. 6A and 6B are scanning electron microscope photographs (× 30) showing the fiber shape of the nonwoven fabric before the treatment with the water jet flow.

Claims (7)

(57) [Claims] 1. A split-fiber composite filament structure having a fiber-forming thermoplastic polymer component as a boundary component and a polyethylene component having a density of 0.95 or more as an independent component, and occupying at least the entire cross-sectional area of the polyethylene component. The ratio is 20
% Or more and 90% or less filament fiber nonwoven fabric, and the constituent filaments are joined together by the polyethylene component, the basis weight is 10 g / m ² to 300 g / m ² or less, The entire surface of the non-woven fabric is embossed into a dot pattern, and the area of one dot of the emboss pattern is 0.2 m.
m is ² or more 10 mm ² or less, and, long-fiber nonwoven fabric ratio of dot embossed portions occupied in the nonwoven fabric total area is characterized in that it is a range that does not exceed 50%. 2. The long-fiber nonwoven fabric according to claim 1, wherein the cross-sectional shape of the composite filament fiber is non-circular. 3. The long-fiber nonwoven fabric according to claim 1, wherein the fineness of the constituent filament fibers is not less than 0.1 denier and not more than 10 denier. 4. A split filament composite filament structure comprising a fiber-forming thermoplastic polymer component as a boundary component and a polyethylene component having a density of 0.95 or more as an independent component, wherein the thermoplastic polymer component and the polyethylene component are peeled off. The weight ratio of each of the components is 20 to 90:80 to 10, and the two components are entangled with each other, and the basis weight is 10 to 300 g / m ^2. The described long-fiber nonwoven fabric. 5. The long-fiber nonwoven fabric according to claim 1, wherein the ratio of the dot embossed portion to the whole area of the nonwoven fabric is 1 to 30%. 6. A composite filament fiber exhibiting a split-type composite structure having a fiber-forming thermoplastic polymer component as a boundary component and a polyethylene component having a density of 0.95 or more as an independent component. After spinning while pulling at a speed of, the spun filament fiber bundle was collided with a collision plate to open the fiber, and then the jet filament group was collected on a porous moving surface, and further collected. A method for producing a long-fiber nonwoven fabric, comprising subjecting a group of filaments to a heat press treatment at a temperature of 50 to 120 ° C. 7. The method according to claim 6, wherein the polyethylene component and the fiber-forming thermoplastic polymer component of the composite filament fiber are split and entangled by a water jet flow after collecting the spun filament group. The method for producing a long-fiber nonwoven fabric according to the above item.