JP2989249B2 - High strength ultrafine fiber nonwoven fabric and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-strength nonwoven fabric having an extremely excellent touch and a method for producing the same. More specifically, the present invention relates to a high-strength ultrafine fiber nonwoven fabric suitable for use as a wide range of fiber cloths such as wipers, filters, surgical gowns, and the like, which have excellent texture, drapeability, and barrier properties, and a method for producing the same.

[Conventional technology]

It is known that ultrafine fibers should be used in order to obtain a nonwoven fabric having an excellent surface feel and texture. However, ultra-fine fibers have low productivity and high cost.Since the diameter of the single yarn is small as it is, workability is poor in terms of fiber opening and sheet formation by carding is inferior, so that a satisfactory nonwoven fabric cannot be obtained. There's a problem. Therefore, many methods have been proposed in which webs are formed using easily splittable conjugate fibers and then converted into ultrafine fibers.

For example, a method in which an incompatible splittable conjugate fiber is made into a web with a card, and then split into fibrils with a high-pressure liquid flow to produce an ultrafine fiber nonwoven fabric. (JP-A-62-133161)
Is disclosed.

However, in the prior art, the fiber length is long (usually 32).
5050 mm), and it is difficult to move due to the high-pressure liquid flow, so that entanglement of the composite fiber exhibiting strength does not proceed and the fiber is further split, and large energy is required and cost is high in order to form an ultrafine fiber. In addition, the strength properties of the obtained ultrafine fiber nonwoven fabric are low, and a binder such as a binder is required to increase the strength. I can't show it enough.

[Problems to be solved by the invention]

The present invention provides a high-strength nonwoven fabric having a high strength, a soft and drape texture unique to microfibers, excellent covering properties and lint-free properties, and a method for producing this high-strength nonwoven fabric at low cost. The purpose is to do.

[Means for solving the problem]

The present invention is as follows. 1. A nonwoven fabric composed of the conjugate short fibers having a fiber length of 20 mm or less and a ratio L / D of the fiber length L to the fiber diameter D of 0.5 × 10 ^{3 to} 2.0 × 10 ^3. A high-strength fine fiber characterized in that ultrafine single fibers of 0.8 denier or less and / or fiber bundles of the ultrafine single fibers obtained by splitting from the splittable conjugate short fibers are three-dimensionally entangled with each other. Fiber non-woven fabric.

2. A web is formed from the conjugate short fibers having a splittable conjugate fiber length of 20 mm or less and a ratio L / D of the fiber length to the fiber diameter D of 0.5 × 10 ^{3 to} 2.0 × 10 ^3. By performing the processing,
A high-strength ultrafine fiber nonwoven fabric characterized in that ultrafine single fibers of 0.8 denier or less and / or a fiber bundle of the fine single fibers obtained by confounding and splitting the splittable composite short fibers are three-dimensionally entangled with each other. Manufacturing method.

 Hereinafter, the present invention will be described in more detail.

The splittable conjugate fiber in the present invention is one in which two or more types of incompatible thermoplastic polymer components having no mutual adhesion are alternately arranged, and as a specific example of the cross-sectional shape,
For example, as shown in FIGS. 1A to 1G, the material is not limited to this as long as it can be split by thermal or mechanical action. In the present invention, the fiber bundle of ultrafine fibers refers to a fiber bundle in which splittable conjugate fibers are split and aggregated, and are not separated. Examples of the combination of the thermoplastic polymer components include polyester / polyolefin, polyester / polyamide, polyamide / polyolefin, polyester / copolyester, polyamide / copolyamide, and the like.
No. 5,650, JP-A-53-38709 and the like.

In the present invention, the splittable conjugate fiber has a fiber length of 20 mm or less and a ratio L / D (hereinafter abbreviated as L / D) of the fiber length L to the fiber diameter D of 0.5 × 10 ^{3 to} 2.0 × 10 ^3. Of the range.

Only by constructing the above-mentioned splittable composite short fibers, high strength (tensile strength, peel strength, tear strength, etc.) and soft, draped texture and covering properties which have not been obtained until now with ultrafine nonwoven fabrics The present invention has been found that they have characteristics such as barrier properties and barrier properties.

It is essential that the splittable conjugate fiber constituting the nonwoven fabric is 20 mm or less in order to achieve the entanglement of the splittable conjugate fiber at the same time as the intermingling of the ultrafine fibers and the entanglement of the ultrafine fibers and the unsplit composite fibers. It is. Preferably, it is less than 15 mm. That is, the present inventors have found that if the fiber length is 20 mm or more, splitting of splittable conjugate fibers by high-pressure water flow is not sufficiently promoted or requires extremely high energy.

On the other hand, L / D of 0.5 × 10 ^{3 to} 2.0 × 10 ³ is necessary for expressing high strength that cannot be obtained with a conventional ultrafine fiber nonwoven fabric, and the preferable range is 0.8 × 10 ^{3 to} 1.5. × 10 ^3.

L / D of the splittable conjugate short fiber is found to have an important relationship with the easiness of entanglement of the fibers by examination of the present inventors, and L / D is less than 0.5 × 10 ³ ; and When it exceeds 2.0 × 10 ³ , the desired nonwoven fabric strength cannot be obtained in any case, and practical high strength can be obtained only in the range of 0.5 × 10 ^{3 to} 2.0 × 10 ³ of the present invention. This surprising fact is presumed to be: That is, the easiness of movement of the fiber due to the columnar water flow or the like is large as the L / D is small, that is, thick and short, and the entanglement between the fibers is large. On the other hand, the number of points of mutual contact between the fibers increases as the fibers are thinner and longer, that is, as the L / D is larger.

However, if the L / D is too large, the movement of the fibers during entanglement is suppressed, and the entanglement between the fibers is reduced.
Therefore, the optimum range for maximizing the entanglement density between fibers is
It is understood that L / D is present and this range is between 0.5 × 10 ^{3 and} 2.0 × 10 ³ .

The cross-section of the splittable conjugate fiber constituting the present invention may be circular or various non-circular cross-sections. In the case of a circular shape, the diameter of the single yarn is determined from the value obtained by directly measuring the diameter. In the case of the irregularly shaped yarn, the fineness (denier) of the single yarn is measured by a gravimetric method. Is assumed to be a circle, and is represented by an average diameter obtained by the following equation.

The denier of the splittable conjugate fiber used in the present invention is preferably 1 to 6 denier. If it is less than 1 denier, spinning of the conjugate fiber is difficult, and if it is more than 6 denier, the number of divisions increases to obtain ultrafine fibers of 0.8 denier or less after splitting, which is not preferable in production. A more preferable splittable conjugate fiber is 1 to 3 denier in view of spinnability and cost, and the number of splits is usually 2 to 12 suitably.

Further, in the present invention, the denier of the ultrafine monofilament composed of at least one component obtained by splitting from the splittable conjugate fiber is 0.8 denier or less. If it exceeds 0.8 denier, the hand of the nonwoven fabric becomes hard, the feel becomes rough, and the covering properties and barrier properties to be obtained in the present invention become poor. In this respect, it is preferable that the ultrafine single fiber is 0.3 denier or less.

The nonwoven fabric of the present invention is composed of the above-mentioned splittable conjugate fiber having a specific fiber length and L / D, and is an ultrafine single fiber of 0.8 denier or less and / or the ultrafine single fiber obtained by splitting the splittable composite fiber. Are characterized in that the fiber bundles are intertwined three-dimensionally.

The state of entanglement of the nonwoven fabric of the present invention is a part where the ultrafine single fibers completely separated are entangled with each other, a part where the fiber bundles of the ultrafine single fibers are entangled with each other, and the ultrafine single fiber and the ultrafine single fiber. The portions in which the fiber bundles are entangled with each other are mixed to form an integral structure.

Even if the fibers are not split at all or are mixed with partially split conjugate fibers, this does not hinder the object of the present invention. Although the ratio of undivided fibers that are not split at all varies depending on the basis weight of the nonwoven fabric and the manufacturing conditions, it is a preferred embodiment of the present invention that the ratio is less than 50%. However, depending on the use of the non-woven fabric, for example, a thick non-woven fabric in which only the surface layer of the non-woven fabric is split and the ultrafine fibers are entangled with each other is also included in the present invention.

Since the nonwoven fabric of the present invention has such a configuration, it is an ultrafine fiber nonwoven fabric, but has an unprecedented high strength due to the intermingling of the entanglement including the fiber bundle in which the ultrafine fibers produced by splitting are converged. . Therefore, it can be used as it is as a non-binder high-strength ultra-fine nonwoven fabric, and can be suitably used for wipers, surgical gowns, filters, etc., but depending on the application, coloring, water repellency, finishing treatment such as antistatic treatment, and Performing binder processing does not hinder the present invention at all. The following are some preferred applications of the present invention.

For example, medical materials such as surgical packs, surgical gowns, and underpads, and sanitary materials such as diapers, napkins, and masks. In these applications, the characteristics of the nonwoven fabric of the present invention having rich drape property and high strength are well utilized.

In particular, when the nonwoven fabric of the present invention is used for surgical gowns, the property of having excellent liquid barrier properties particularly required for surgical gowns is well utilized. The nonwoven fabric of the present invention itself has a high liquid barrier property because ultrafine fibers split from short fibers having the specified fiber length L / D are entangled with high density. As an attempt to obtain a liquid barrier property required for surgical gowns with a conventional nonwoven fabric, for example, as disclosed in JP-A-59-94659, polyester (polyethylene terephthalate) is composed of fine fibrils. Laminating or mixing wood pulp or jetting a columnar water stream onto a sheet obtained by mixing, the pulp has been devised to increase the density of the nonwoven fabric by entanglement with polyester in a so-called "stuffing" manner. It has been confirmed that a selected liquid barrier property can be obtained without using such a specially filled binder fiber.

When the nonwoven fabric of the present invention is used for an interlining for clothing, the features of uniformity, high strength, and good surface covering properties are well utilized and preferred. It is also suitable for industrial wiping cloths such as in the electronic field. This is because the nonwoven fabric of the present invention is excellent in lint-free properties due to the fact that the fibers are firmly bonded by entanglement between fibers with no binder, and is excellent in wiping properties because it is flexible. In addition, it is recognized that it is suitable as a filter for gases and liquids, in particular, a so-called pre-filter having particles of 5 to 25 μm. This is a result of the property that the ultrafine fibers are densely entangled in the nonwoven fabric is sufficiently utilized for the filter function.

When the nonwoven fabric of the present invention is used as a coating base fabric, the characteristics of the nonwoven fabric of the present invention are well utilized. That is, although attempts have been made to use a conventional nonwoven fabric as a coating base fabric instead of the conventional woven or knitted fabric, these nonwoven fabrics have weaker delamination strength than woven or knitted fabrics. In many cases, a coated product obtained by merely coating polyurethane or polyvinyl chloride causes a peeling phenomenon between the layers of the nonwoven fabric during use, and is often unsuitable for practical use.

In order to remedy this drawback, an elastic polymer such as polyurethane, polyacrylate, SBR, MBR, or NBR is previously applied to a nonwoven fabric as a binder, and then the surface is coated with polyurethane, polyvinyl chloride, or the like. However, in this case, it was unavoidable that the texture became paper-like and the quality was inferior to that of the woven or knitted fabric.

On the other hand, the nonwoven fabric of the present invention has an extremely high delamination strength as compared with conventional nonwoven fabrics, and thus can be used as a coating base fabric without a binder.
It has new features that are not found in conventional nonwoven fabric base fabrics, are excellent in soft feeling and high in delamination strength.

The use of the nonwoven fabric of the present invention as a base fabric for artificial leather is also a preferred example. For example, this non-woven fabric is used as it is as a base fabric, and polyurethane, vinyl chloride,
By applying a solution or an emulsion of an elastic polymer such as SBR, NBR, MBR or the like with a gravure, a doctor knife or the like, an artificial leather like a silver surface can be obtained. in this case,
If necessary, it is more preferable to impregnate the nonwoven fabric with an elastic polymer such as polyurethane and form it by dry or wet coagulation before filling the surface coating layer, and then to fill the nonwoven fabric in terms of strength and feeling.

Furthermore, when it is desired to obtain a suede-like artificial leather, the intended suede-like artificial leather is obtained by raising the ultrafine yarn entangled layer of the present nonwoven fabric, impregnating with an elastic polymer or the like as necessary, or dyeing. It is also possible to get.

Next, the method for producing a high-strength ultrafine nonwoven fabric of the present invention forms a web from splittable conjugate fibers having a fiber length of 20 mm or less and an L / D of 0.5 × 10 ^{3 to} 2.0 × 10 ³ , and performs high-speed fluid flow treatment. By doing so, the splittable conjugate fibers are entangled and split,
The method is characterized in that ultrafine single fibers of 0.8 denier or less and / or fiber bundles of the ultrafine single fibers are three-dimensionally entangled with each other, and will be described in detail below.

A splittable conjugate fiber according to the purpose is produced by a known spinning means, and crimping is performed as necessary. The number of crimps is usually selected in the range of 2 to 15 pieces / inch. Next, the fiber length 20 mm or less, the ratio L / D of the fiber length L and the fiber diameter D is 0.5 ×
Cut to obtain short fibers in the range of 10 ^{3 to} 2.0 × 10 ³ .

From the obtained staple fibers, by a conventional method, for example, a dry method such as a card method or an air lay method, or by dispersing the non-crimped staple fibers in water to form a slurry, followed by a long net type, a round net type or the like. The web can be formed by a wet method of making paper with a machine.

Depending on the purpose, two or three types of splittable conjugate fibers forming the web may be mixed or mixed with other short fibers such as wool, cotton, polyester, rayon, nylon and pulp synthetic pulp. Is also possible.

The obtained web is entangled by a high-speed fluid flow and split, and three-dimensionally intertwined. The fluid referred to here is a liquid or a gas, but water is most preferable in terms of ease of handling, cost, and the magnitude of collision energy as a fluid.

When water is used, it depends on the type of yarn and the basis weight of the web, and the processing speed.
The collision is carried out in m ² , preferably in the range of 15 to 150 kg / cm ² . The diameter of the nozzle for jetting the water flow is preferably 0.01 to 1 mm.

The trajectory shape of the water flow may be a straight line parallel to the traveling direction of the papermaking sheet, or a curved shape obtained by the rotational motion of the header equipped with the nozzle or the oscillating motion reciprocating at right angles to the traveling direction of the web. May be. The entanglement of multiple overlapping circular water flow trajectories obtained by the rotational motion is effective because the area of jet of the water flow to the web per one nozzle weight is large, and at the same time, the water flow trajectory lowers the commercial value depending on the application. This is advantageous because it has the advantage that the unevenness of the nonwoven fabric is hard to be seen and the strength ratio of the background of the nonwoven fabric is small.

The method of processing the high-speed water flow on the web may be a method of alternately jetting the water flow on the front and back, or a method of processing only one side. The optimum number of processing times may be selected according to the purpose.

As a water-permeable member that supports the web, a wire net, a plastic net, or the like is used. Depending on the size of the opening area of the supporting member, the shape of the obtained nonwoven fabric can be appropriately obtained from a flat nonwoven fabric having good smoothness to a nonwoven fabric having a perforated weave pattern. That is, if a fine mesh of 60 mesh or more having a small opening area is used as a support member, a non-opening ultrafine nonwoven fabric can be obtained, which is suitable for uses such as surgical gowns, coating base cloths, and separators.
If a wire mesh with large openings of up to 10 mesh is used as the support member, a high-strength ultrafine nonwoven fabric having an opening pattern can be obtained, and is suitably used for industrial and household wipers because of its wiping suitability and lint-free performance.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

In the examples, the measured values are measured by the following methods, and all percentages are% by weight.

1) Tensile strength: JISL1096 strip method 2) Tear strength: JISL1096 single tongue method 3) Delamination strength: Cut the nonwoven fabric into a width of 2.5cm and a length of 13cm. An adhesive tape (trade name: D3 manufactured by Sony Chemical Co., Ltd.)
After adhering 200), they are pressed together at a pressure of 70 g / cm ² at 200 ° C. for 30 seconds.

A cut is made between the adhesive tape and the nonwoven fabric of the measurement sample thus obtained, and both ends are gripped with an autograph chuck to perform measurement. The autograph measurement conditions are set as follows.

Tensile speed: 10 cm / min Chart speed: 10 cm / min In this case, the tape is strong, and the tape and the non-woven fabric are firmly bonded, so the tape is cut when the tape is peeled off from the sample. The peeling force acts so as to peel off one part of the nonwoven fabric from another part without peeling or peeling off the adhesive surface between the tape and the nonwoven fabric. Therefore, the delamination strength of the nonwoven fabric can be measured by this method.

An average value of a total of six values is obtained by selecting three values having a larger intensity value and three values having a smaller intensity value from a stress strain curve obtained when the measurement is performed by an autograph. The number of tests on the measurement sample shall be 5. Such a measurement is similarly performed in the vertical direction (hereinafter abbreviated as MD) and the horizontal direction (hereinafter abbreviated as CD) of the nonwoven fabric, and the delamination strength of the nonwoven fabric is determined by the average value of the MD and CD.

4) Flexibility: The average value of the JISL1096 45 ゜ cantilever method MD and CD is used as the flexibility.

Example 1 Polyethylene terephthalate was used as a first component, and a 1: 1 blend polymer of nylon 6 and nylon 612 was used as a second component, and had a cross section similar to that of FIG. 1A at a ratio of 8: 2 (volume ratio). 1.0 denier splittable composite fiber was obtained. Next, after crimping at .10 pieces / inch to an indenting crimping machine, the fiber was cut to a fiber length of 12.5 mm with a cutter to obtain a composite short fiber (L / D: 1.2 × 10 ³ ). The short fibers were formed into a 40 g / m ² dry web by a card air array method. 30 kg / cm ² using an injection nozzle with a hole diameter of 0.20 mm and a hole distance of 20 mm from the web side
, The fibers were entangled with each other and split to produce entangled ultrafine single fibers and / or ultrafine fiber bundles. Both sides were treated in the same manner, dried by spraying and dried to obtain an ultrafine fiber nonwoven fabric. The denier of this nonwoven fabric was 0.1 denier. Physical properties showed the following values.

Tensile strength (MD / CD): 2.4 / 1.9kg / cm Tear strength (MD / CD): 1.0 / 0.8kg Delamination strength: 1.8kg / cm Flexibility (MD / CD average): 25mm Nonwoven fabric obtained here Was observed with a scanning electron microscope. As a result, splitting of the composite fiber was almost completely achieved, and three-dimensional interlacing in which the ultrafine single fiber and the ultrafine single fiber bundle were permeated was observed. As described above, it was found that the nonwoven fabric of the present invention has extremely high strength and excellent soft feeling and drapability while being an ultrafine fiber.

Comparative Example 1 0.1d (3 μm) atoms of polyethylene terephthalate were made directly by spinning and cut to a length of 3 mm (L / D was 1
0 ³ ). This was made into a web of 40 g / m ² by a wet papermaking method and subjected to a columnar flow treatment. The physical properties of the obtained nonwoven fabric were as follows, and the tear strength was sometimes low.

Tensile strength (MD / CD): 1.4 / 1.2 kg / cm Tear strength (MD / CD): 0.2 / 0.2 kg Delamination strength: 910 g / cm Flexibility (MD / CD average): 24 mm Comparative Example 2 In Example 1 Cut the used splittable conjugate fiber to 32 mm,
(L / D is 3.1 × 10 ³ ). After forming a dry web in the same manner as in Example 1, the jet fluid treatment was performed. The physical properties of the obtained nonwoven fabric were as follows, and the tensile strength was particularly low.

Tensile strength (MD / CD): 0.8 / 0.7kg / cm Tear strength (MD / CD): 1.4 / 1.2kg Delamination strength: 0.31kg / cm Softness (MD / CD average): 36mm Nonwoven fabric of Comparative Example 2 When observed with a scanning electron microscope, the splittable conjugate fibers were not sufficiently split, and many undivided conjugate fibers were observed.

Example 2 Short fibers (L / D: 0.98 × 10 ³ ) having a fiber length of 10 mm were obtained from the same splittable conjugate fiber used in Example 1 without crimping. Disperse this short fiber in water and wet papermaking method at 30 g / m ²
A web was formed, and a high-pressure injection treatment (water pressure
25 kg / cm ² ) to obtain a microfiber nonwoven fabric. This non-woven fabric is rich in drape, 30g / m ² , and it is thin and has excellent covering properties. It was not suitable for interlining. The physical properties of the obtained nonwoven fabric are shown below.

Tensile strength (MD / CD): 1.6 / 1.3kg / cm Tear strength (MD / CD): 0.8 / 0.5kg Flexibility (MD / CD average): 24mm Example 3 Polyethylene terephthalate as the first component and polypropylene as the first component A 1.5 denier splittable conjugate fiber having a cross section similar to that of FIG. 1 (A) was obtained at a ratio of 8: 2 (volume ratio) as two components. After crimping (10 crimps per inch), cut and composite short fibers with a fiber length of 12 mm (L / D is 0.98 × 1
0 ³ ) was obtained. 300 g / m from this short fiber by the card air array method
² web, nozzle diameter 0.2mm, nozzle pitch
5mm, Nozzle row number 18 rows, paper sheet and nozzle spacing 3
0mm, nozzle header rotation speed 150rpm, seat speed 5m /
The column was treated in minutes. Physical properties were as follows.

Tensile strength (MD / CD): 14.5 / 13.8kg / cm Tear strength (MD / CD): 10.4 / 10.1kg Delamination strength: 2,210g / cm In this entangled sheet, polytetramethylene glycol for polyol component and polytetramethylene glycol for isocyanate component P, P'-diphenylmethane diisocyanate was impregnated with a 15% dimethylformamide solution of polyurethane using ethylene glycol as a chain extender, squeezed to a squeezing ratio of 300%, and then coagulated in water. After drying, one side of the resulting impregnated sheet was
Buffing was performed with a belt sander equipped with 0 mesh emery paper. Next, the ground surface was heated and pressed with a calender roll having a surface temperature of 150 ° C. This buffing / heat-pressed surface was coated with 30% dimethylformamide having a composition of polybutylene adipate, P, P'-diphenylmethane diisocyanate, and ethylene glycol using a gravure roll, coagulated in water, and then dried. In addition, polyethylene glycol, P,
A 40% solution of a mixed solvent of P'-diphenylmethane diisocyanate, ethylenediamine methyl ethyl ketone and isopropyl alcohol was coated with gravure roll, and the solvent was dried and removed at 130 ° C. The thus-obtained silver-like sheet-like material has an extremely good surface smoothness of the polyurethane coating layer, an excellent feeling of flexibility, and also has the following physical properties. It had sufficient strength to the extent that it could be obtained.

Tensile strength (MD / CD): 20.8 / 20.2 kg / cm Tear strength (MD / CD): 10.8 / 10.5 kg Flexibility (MD / CD average): 74 mm Example 4 Similar splitting as used in Example 3 A 80 g / cm ² web was formed from the conjugated short fibers in the same manner. This was subjected to high-pressure injection treatment at a water pressure of 40 kg / cm ² and a net speed of 20 m / min in the same manner as in Example 3 to obtain an ultrafine fiber nonwoven fabric. The physical properties of this nonwoven fabric were as follows.

Tensile strength (MD / CD): 4.8 / 4.2kg / cm Tear strength (MD / CD): 2.7 / 2.3kg Delamination strength: 2.0kg / cm Flexibility (MD / CD average): 32mm Polyurethane (concentration: 30%) dissolved in ether-based poramide was coated with a doctor knife to a coating amount of 45 g / m ² . The resulting coating has a very soft feel because the non-woven fabric has no binder, and the surface of the formed polyurethane film has a fine and fine texture that is as natural and luxurious as the silver surface of natural leather. Met. Further, since the delamination strength is sufficiently high, it was confirmed that there was no damage such as delamination during use even when used as a material such as a chair upholstery.

Example 5 Similar to the splittable conjugate fiber used in Example 1, uncrimped short fiber 10 cm (L / D: 1.0 × 10 ³ ), rayon fiber 1 denier, and 8 mm short fiber were wet-processed at a ratio of 7: 3. To form a web of 55 g / m ² . In the same manner as in Example 1, a water pressure treatment of a water pressure of 35 kg / cm ² was performed. Physical properties were as follows. This nonwoven fabric has both the antistatic property of cellulose, the hygroscopic property, the wiping property of ultrafine fibers, and the lint-free property, and was suitable for a wiping cloth for electronics, a liner of a floppy disk, and the like.

Tensile strength (MD / CD): 4.2 / 3.8 kg / cm Tear strength (MD / CD): 2.1 / 2.0 kg Delamination strength: 1.2 kg / cm Flexibility (MD / CD average): 32 mm Example 6 Example 5 The web used in step 2 was placed on a 14-mesh wire net, and subjected to high-pressure injection under the same conditions as in Example 5. Since the obtained nonwoven fabric had a perforated weave pattern, the wiping properties were further improved, and the nonwoven fabric had a performance of withstanding repeated washing 20 times, and was suitable as a wiping cloth capable of washing resistance.

 The physical properties are shown below.

Tensile strength (MD / CD): 3.9 / 3.6 kg / cm Tear strength (MD / CD): 1.7 / 1.5 kg Flexibility (MD / CD average): 33 mm [Effect of the present invention] High strength by the manufacturing method of the present invention The ultrafine nonwoven fabric has a high strength that cannot be obtained with a conventional ultrafine nonwoven fabric, and can be manufactured at low cost. In addition, it has a soft and draped texture peculiar to the ultrafine fiber,
Excellent lint-free properties.

[Brief description of the drawings]

1 (A) to 1 (G) are cross-sectional views schematically showing examples of a splittable conjugate fiber used in the present invention. 1... Incompatible thermoplastic weight having no mutual adhesiveness Coalesced (for example, polyester), 2... Incompatible thermoplastic polymer (for example, polyolefin) having no mutual adhesion.

Claims (2)

(57) [Claims] 1. A nonwoven fabric comprising a splittable conjugate fiber having a fiber length of 20 mm or less and a ratio L / D of the fiber length L to the fiber diameter D of 0.5 × 10 ³ to 2 × 10 ^3. Characterized in that ultrafine single fibers of 0.8 denier or less and / or fiber bundles of the ultrafine single fibers obtained by splitting the splittable conjugate short fibers are three-dimensionally entangled with each other. High-strength microfiber nonwoven fabric 2. A web is formed from the conjugate short fibers having a splittable conjugate fiber having a fiber length of 20 mm or less and a ratio L / D of the fiber length to the fiber diameter D of 0.5 × 10 ³ to 2 × 10 ³ , By performing the high-speed fluid flow treatment, the splittable conjugate short fibers are entangled and three-dimensionally entangled with each other in ultrafine single fibers of 0.8 denier or less and / or fiber bundles obtained by splitting and splitting. A method for producing a high-strength ultrafine fiber nonwoven fabric, characterized in that: