JPH04185751A - High-strength extermery thin nonwoven fabric and its production - Google Patents

Abstract

PURPOSE:To obtain the title nonwoven fabric having excellent handle, drape properties, etc., by forming web from specific separable conjugate short fibers, subjecting the web to high-speed fluid treatment, interlacing the conjugate short fibers, dividing the fibers to form extremely thin single fibers, etc., and mutually interlacing the web in a three-dimensional way. CONSTITUTION:Web is formed from separable conjugate short fibers having <=20mm (preferably <=15mm) fiber length and a ratio L/D of fiber length (L) and fiber diameter (D) of 0.5X10<3> to 2X10<3> (preferably 0.8X10<3> to 1.5X10<3>), then treated with high-speed fluid, the conjugate short fibers are interlaced and divided to give extremely thin fibers and/or fiber bundle of the single fibers having <=0.8 denier (preferably <=0.3 denier), which is interlaced in a three- dimensional way to give the objective nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a high-strength nonwoven fabric with extremely excellent texture and a method for producing the same. More specifically, the present invention relates to a high-strength ultrafine fiber nonwoven fabric that has excellent texture, drapability, and barrier properties and is suitable for a wide range of uses such as wipers, filters, and surgical gowns, and a method for producing the same.

[Conventional technology]

It is known that ultrafine fibers can be used to obtain nonwoven fabrics with excellent surface feel and texture.

However, ultrafine fibers have low productivity and high cost,
If used as it is, there is a problem that a satisfactory nonwoven fabric cannot be obtained because the diameter of the single filaments is small, so the workability is poor in terms of opening properties, and sheet formation with curved ink is also poor. Therefore, a number of methods have been proposed for forming a web using highly splittable conjugate fibers and then producing ultrafine fibers.

For example, incompatible splittable conjugate fibers are made into a web using a cart, and then split and fibrillated using a high-pressure liquid flow to create an ultrafine fiber nonwoven fabric. (Japanese Unexamined Patent Publication No. 133161/1983) is disclosed.

However, in the conventional technology, the fiber length is long (usually 32
~50 mm), which is difficult to move due to the high-pressure liquid flow, so the intertwining of the composite fibers that develop strength progresses, and further splitting to form polar fibers requires a large amount of energy and is expensive. In addition, the strength properties of the obtained microfiber nonwoven fabric are low, and in order to increase the strength, a binder and interfiber adhesive components are required, so even with partial bonding, the flexibility is poor and the texture is hard. cannot fully demonstrate its characteristics.

[Invention or problem to be solved]

The present invention provides a high-strength nonwoven fabric that has high strength, has a soft drape texture unique to ultrafine fibers, and has excellent cover link properties and lint-free properties, and a method for manufacturing this high-strength nonwoven fabric at low cost. The purpose is to

[Failure to solve the problem]

The present invention is as follows. That is, the fiber length of the splittable conjugate fiber is 20 mm or less, and the ratio of fiber length to fiber diameter L/D is 0.5X10:'~2
．． A nonwoven fabric composed of 0x103 composite short fibers, which is obtained by splitting the splittable composite short fibers.
A high-strength ultrafine fiber nonwoven fabric characterized in that ultrafine single fibers of denier or less and/or fiber bundles of the ultrafine single fibers are three-dimensionally entangled with each other.

2. When the fiber length of the splittable composite fiber is 20 mm, the ratio of the fiber length to the fiber diameter is 0.5 x 10' to 2.
．． A web is formed from the composite short fibers of 0x103 and subjected to high-speed fluid flow treatment to entangle and split the splittable composite short fibers to produce ultrafine single fibers of 0.8 deniers or less and/or A method for producing a high-strength ultrafine fiber nonwoven fabric, which comprises three-dimensionally entangling fiber bundles of the fine single fibers.

The present invention will be explained in more detail below.

In the present invention, the splittable conjugate fiber is made up of two or more non-adhesive, incompatible thermoplastic polymer components arranged alternately, and specific examples of the cross-sectional shape thereof include:
Examples include those shown in FIGS. 1(A) to (G), and any fibers that can be split by thermal or mechanical action are not limited to these.

In the present invention, the fiber bundle of ultrafine single fibers refers to splittable conjugate fibers that are split and aggregated and are not separated into pieces.

Further, as the combination of the above-mentioned thermoplastic polymer components, for example, polyester/polyolefin, polyester/polyamide, polyamide/polyolefin, polyester/copolyester, polyamide/copolyamide, etc. are used. It can be obtained by known methods such as those disclosed in Japanese Patent Application Laid-Open No. 53-38709.

In the present invention, the splittable conjugate fiber has a fiber length of 20 mm or less, and the ratio of fiber length to fiber diameter is L/D (hereinafter referred to as L/D).
) or in the range of 0.5XIO' to 2.0x103.

By using the above-mentioned limited splittable conjugate staple fibers, we were able to achieve high strength (
The present invention was completed based on the discovery that the material has characteristics such as tensile strength, peel strength, tear strength, etc.), a soft drape texture, covering properties, and barrier properties.

The reason why the splittable conjugate fibers constituting the nonwoven fabric is less than 20I]ll11 is to ensure that the splittable conjugate fibers are thoroughly split at the same time as they are intertwined to achieve intertwining of the ultrafine fibers and entanglement of the ultrafine fibers and the unsplit conjugate fibers. is required. Preferably] less than 5 mm. That is, a! The present inventors have found that if the # length is 20I [1I] or more, the splitting of splittable conjugate fibers by high-pressure water flow is not sufficiently promoted, or very high energy is required.

On the other hand, L/D is 0.5×103~2. QXlO" is necessary to develop high strength that cannot be obtained with conventional ultrafine fiber nonwoven fabrics, and the preferred range is 0.8X
IO3 to 1.5 XIO3.

The present inventors have found that the L/D of the splittable composite short fibers has an important relationship with the ease with which the fibers are entangled with each other, and when the L/D is less than 0.5XIO', 2
．． If it exceeds 0XIO', the desired nonwoven fabric strength cannot be obtained, and the present invention's 0.5X 103 to 2.0X
Practical high strength can only be obtained in the IO' range. This surprising fact can be estimated as follows. That is, the ease of movement of the fibers due to columnar water flow, etc. is greater as L/D is smaller, that is, the thicker and shorter the fibers are, and the entanglement between the fibers becomes greater. On the other hand, the number of contact points between fibers increases as the fibers become thinner and longer, that is, as L/D increases.

However, if the L/D ratio is too large, the movement of the fibers during intertwining will be suppressed and the entanglement between the fibers will become smaller.

Therefore, there is an optimal range of L/D that maximizes the intertwining density of fibers, and this range is 0.5X]03 to 2.0X
103.

The cross section of the splittable conjugate fiber constituting the present invention may be circular or may have various non-circular cross sections. In the case of a circular shape, the diameter of the single yarn is determined by directly measuring its diameter.In the case of a yarn with an irregular cross section, the diameter of the single yarn is determined by measuring its fineness (denier) using the gravimetric method, and this denier is determined as the diameter of the single yarn. It is expressed by the average diameter obtained from the following formula assuming that it is circular.

(Left below) (Here R = Diameter of single yarn (μm) ζ = Density of polymer constituting the single yarn (g/cd) d = Fineness of single yarn (denier) π = Circumference of the invention The denier of the splittable conjugate fiber used for this is preferably 1 to 6 denier.If the denier is less than 1 denier, it will be difficult to spin the conjugate fiber, and if the denier is 6 denier or more, the number of splits will be required to obtain ultrafine fibers of 0.8 denier or less after splitting. From the viewpoint of spinnability and cost, the more preferable splittable conjugate fiber is 1 to 3 deniers, and the number of splits is usually 2 to 12.
is preferably used.

Further, in the present invention, the denier of the ultrafine single fibers made of at least one component obtained by splitting the splittable conjugate fibers is 0.8 denier or less.

If it exceeds 0.8 denier, the texture of the nonwoven fabric will be hard and rough to the touch, and the covering and barrier properties that are intended to be obtained in the present invention will be poor. In this respect, it is preferable that the ultrafine single fibers have a denier of 0.3 or less.

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

The state of the entanglement of the nonwoven fabric of the present invention includes parts where the ultra-fine single fibers are completely separated or intertwined with each other, fiber bundles of ultra-fine single fibers or intertwined parts with each other, and parts where the ultra-fine single fibers are intertwined with each other. Fiber bundles or mutually intertwined parts are mixed,
It has an integrated structure.

There is no problem in achieving the object of the present invention even if the fibers are not split at all or if there are composite edges that are partially split.

The percentage of unsplit fibers that have not been split at all is the basis weight of the nonwoven fabric.
It is a preferred embodiment of the present invention that the ratio varies depending on the manufacturing conditions, or that it is less than 50%. However, depending on the use of the nonwoven fabric, for example, a thick nonwoven fabric in which only the surface layer of the nonwoven fabric is split and the ultrafine fibers are intertwined with each other is also included in the present invention.

Because the nonwoven fabric of the present invention has such a structure, it has unprecedented high strength due to the ultrafine fiber nonwoven fabric, the ultrafine single fibers produced by splitting, or the entanglement or mixture of converged fiber bundles. . Therefore, as a binder-free, high-strength ultrafine nonwoven fabric, it is possible to use it as it is for applications such as wipers, surgical gowns, and filters. The present invention is not hindered in any way by applying binder processing as appropriate. Some preferred usage examples of the present invention are shown below.

Examples include medical materials such as surgical bags, underpads, and sanitary materials such as diapers, napkins, and masks. In these applications, the excellent drapability and high strength characteristics of the nonwoven fabric of the present invention are well utilized.

In particular, when the nonwoven fabric of the present invention is used for surgical gowns, the property of excellent liquid barrier properties, which is particularly required for surgical gowns, can be effectively utilized. Since the nonwoven fabric of the present invention is made of ultrafine fibers split from short fibers having a specified fiber length L/D and intertwined at a high density, the nonwoven fabric itself has high liquid repellency. As an attempt to obtain the liquid barrier properties required for surgical gowns using conventional non-woven fabrics, for example, Japanese Patent Application Laid-Open No. 59-946
As disclosed in Publication No. 59, a columnar water stream is sprayed onto a sheet obtained by laminating or mixing polyester (bolyene terephthalate) with wood pulp composed of fine fibrils, and a valve is created. In other words, it has been devised to increase the density of the nonwoven fabric by entangling it with polyester in a packing manner.In the present invention, excellent liquid barrier properties can be achieved without using such special packing binder fibers. It has been confirmed that it can be obtained.

When the nonwoven fabric of the present invention is used as an interlining for clothing, it is also suitable because its characteristics of uniformity, high strength, and good surface cover linkability are well utilized. It is also suitable for industrial wipe pink cloth such as in the electronic field. This is because the nonwoven fabric of the present invention or no binder has excellent lint-free properties because the fibers are firmly joined by interlacing the fibers, and is flexible and has excellent wiping properties. Furthermore, it is also recognized to be suitable as a filter for gases and liquids, especially as a so-called pre-filter that passes particles of 5 to 25 μm. This is a result of the fact that the ultrafine fibers in the nonwoven fabric are tightly intertwined, or are fully utilized for the filter function.

When using the nonwoven fabric of the present invention as a coating base fabric,
The characteristics of the nonwoven fabric of the present invention are well utilized.

In other words, attempts have been made to use conventional non-woven fabrics as coating base fabrics in place of conventional woven or knitted base fabrics.In the case of these non-woven fabrics, the delamination strength is weaker than that of woven or knitted fabrics, so When coated with polyurethane or polyvinyl chloride, the resulting coated product often suffers from peeling between the layers of the nonwoven fabric during use, making it unsuitable for practical use.

To improve the second drawback, it is also possible to apply an elastic polymer such as polyurethane, polyacrylic acid ester, SBR, MBR, NBR, etc. as a binder to the nonwoven fabric in advance, and then coat the surface with polyurethane, polyvinyl chloride, etc. However, in this case, it was inevitable that the texture would be paper-like and the quality would be inferior to that of woven or knitted fabrics.

On the other hand, the nonwoven fabric of the present invention has an extremely high delamination strength compared to conventional nonwoven fabrics, so it can be used as a coating base fabric without a binder, which is not seen in conventional nonwoven fabrics. It has new features such as an excellent soft texture and high interlayer peel strength.

One suitable example is to use the nonwoven fabric of the present invention as a base fabric for artificial leather. For example, if this nonwoven fabric is used as a base fabric, its surface may be coated with polyurethane, vinyl chloride, S.
Silver thin artificial leather can be obtained by applying a solution or emulsion of an elastic polymer such as BR, NBR, MBR, etc. with a Dalahia, doctor knife, etc. In this case, it is more preferable in terms of strength and texture to impregnate the nonwoven fabric with an elastic polymer such as polyurethane and dry or wet coagulate and fill it before forming the surface coating layer, if necessary.

Furthermore, if you want to obtain suede-like artificial leather, the ultrafine interlaced layer of this nonwoven fabric is raised, impregnated with an elastic polymer, etc. as necessary, or dyed to obtain the desired suede-like artificial leather. It is also possible to obtain

Next, the manufacturing method of the high-strength ultrafine nonwoven fabric of the present invention is as follows: The fiber length is 20 mm or less, and the L/D is 0.5X]O'' to 2.0X.
A web is formed from the splittable conjugate fibers of No. 103 and subjected to high-speed fluid flow treatment to entangle and split the splittable conjugate fibers, resulting in ultrafine single fibers of 0.8 denier or less and/or the ultrafine single fibers. This method is characterized by intertwining fiber bundles with each other in a three-dimensional manner, and will be explained in detail below.

A splittable conjugate fiber according to the purpose is produced using known spinning means, and crimped if necessary.

The number of crimps is usually selected in the range of 2 to 15 crimps/inch. Next, short fibers are obtained by cutting the fibers so that the fiber length is 20 mm or less and the ratio L/D of fiber length to fiber diameter is in the range of 0.5×10 3 to 2.0×10 3 .

The obtained short fibers are processed by a conventional method such as a dry method such as a card method or an airlay method, or by dispersing the non-crimped short fibers in water to form a slurry, and then using a Fourdrinier method or a round net method. It is possible to form a web using the wet method of making paper using a paper making machine.

The type of splittable composite fiber that forms the web depends on the purpose.
It is also possible to mix one type or three types, or to mix other short fibers such as wool, cotton, polyester, rayon, nylon, and valve synthetic pulp.

The resulting web is entangled by a high-speed fluid flow and split into three-dimensionally intricately intertwined webs. The fluid here is
Water is most preferable in terms of ease of handling, cost, and high collision energy as a fluid.

When using water, it depends on the type of yarn, web weight, and processing speed, or if you want to obtain the desired well-divided, high-strength nonwoven fabric, use water pressure of 5 to 200 kg.
/cnf, preferably in the range of 15 to 150 kg/d. The diameter of the nozzle that sprays the water stream is 0.01 to 1
暉 or preferable.

The trajectory shape of the water stream may be a straight line parallel to the direction of travel of the paper sheet, or it may be a curved shape obtained by the rotational movement of a header equipped with a nozzle or the vibration motion that reciprocates at right angles to the direction of web travel. It's okay. The intertwining of the multiple circular water flow trajectories obtained by rotational motion increases the jetting area of the water flow against the web per nozzle weight, which is efficient, but at the same time, the water flow trajectories may reduce the product value depending on the application. It is preferable because it has advantages such as less visible spots and a small strength ratio between warp and warp of the nonwoven fabric.

The method of treating the web with a high-speed water stream may be to spray the water stream alternately on the front and back sides, or to treat only one side. Furthermore, it is advisable to select optimal conditions for the number of times of processing depending on the purpose.

A wire mesh, a plastic net, etc. are used as the water-permeable member that supports the web. Depending on the size of the aperture area of the supporting member, the shape of the obtained nonwoven fabric can range from a flat and smooth non-perforated fabric to one with an apertured texture pattern. That is, if a fine wire mesh of 60 mesh or more with a small pore area is used as a supporting member, an ultrafine nonwoven fabric with no pores can be obtained, which is suitable for uses such as surgical gowns, coated base fabrics, and separators.
If a wire mesh with large openings of 0 to 10 meshes is used as the supporting member, a high-strength ultrafine nonwoven fabric with an opening pattern can be obtained, which is suitably used for industrial and household wipers due to its wiping suitability and lint-free performance.

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

In the Examples, the measured values were determined by the following method, and all percentages are by weight.

1) Tensile strength: J [5L1096 strip method 2
) Tear strength: JISL1096 single tongue method 3) Interlayer peel strength Cut the nonwoven fabric into 2.5 cm width and 13 cm length.

Adhesive tape (manufactured by Sony Chemical Co., Ltd.,
After adhering the product (trade name: D 3200), they were pressed together at 200°C for 30 seconds at a pressure of 70 g/ci.

A slit is made between the adhesive tape and the nonwoven fabric of the thus obtained measurement sasiple, and both ends are gripped with an autograph chuck and measured.

The measurement conditions for the autograph are set as follows.

Tensile speed: 10 marks/min Chart speed: 10 cm/min In this case, the tape is strong and the tape and the nonwoven fabric are firmly bonded, so when the tape of the measurement sample or the nonwoven fabric is peeled off from the measurement sample, The peeling force acts to peel one part of the nonwoven fabric from the other part. Peel strength can also be measured.

From the strain curve obtained when performing the above measurement using an autograph, three of the larger intensity values and three of the smaller intensity values are selected, and the average value of the six values in total is obtained. The number of test samples for measurement is 5. Such measurements are carried out in the same manner in the longitudinal direction (hereinafter abbreviated as MD) and in the lateral direction (hereinafter abbreviated as CD) of the nonwoven fabric, and the average value of the MD and CD is calculated as the delamination strength of the nonwoven fabric. .

4) Flexibility JISL1096 45° cantilever
The average value of the modulus MD and CD is taken as the degree of flexibility.

Example 1 Polyethylene terephthalate was used as the first component, 1.1 precitopolymer of Nylore 6 and NyloS 612 was used as the second component, and the ratio was 82 (volume ratio). , 0 guineas splittable composite fibers were obtained.

Next, after applying 10 crimps/inch with a push-crimping machine, the fibers were canted with a cutter to a fiber length of 12.5 mm to obtain composite short fibers (L/D is 1.2×I03). The short fibers were cartonied and a dry web of 40 g/rrf was formed by the A method.

treated from the web side at a pressure of 30 kg/cnr using an injection nozzle with a hole diameter of 0.20 mm and a distance between holes of 20 mm,
The conjugate short fibers were entangled and split to cause intertwining of ultrafine single fibers and/or ultrafine fiber bundles. Both sides were treated in the same manner and dried after spraying to obtain an ultrafine fiber nonwoven fabric. The ultrafine single fiber denier of this nonwoven fabric was 0.1 denier. The physical properties showed the following values.

Tensile strength (MD/CD): 2.4/1.
0 kg/cm tear strength (MD/CD):
1.010.8kg Peeling strength: 1.8
kg/cm flexibility (MD-CD average) = 25 When the nonwoven fabric obtained here was observed with a scanning electron microscope, splitting of the composite fibers was almost completely achieved, and ultrafine single fibers and ultrafine single fibers were observed. I could see that there was some kind of bunching or intricate three-dimensional interlacing. As described above, it has been found that the nonwoven fabric of the present invention has extremely high strength even though it is made of ultrafine fibers, and also has excellent soft feel and trepability.

Comparative Example 1 A 0.16 (3 μm) atom of polyethylene terephthalate was made by direct spinning method, and a force was applied to a length of 3 rMl (L/D is 103). This was processed using the wet papermaking method to produce 4 (] g/r
ri web and subjected to columnar flow treatment. The physical properties of the obtained nonwoven fabric were as follows, and the tear strength was particularly low.

Tensile strength (MD/CD): 1.4/1.
2 kg, cm tear strength (MD/CD):
0.210.2 kg Delamination strength 9]O
g/cm flexibility (MD-CD average): 24 m
Comparative Example 2 The splittable conjugate fiber used in Example 1 was cut into 32111111 pieces (L/D was 3.1XIO"), and a dry web was prepared in the same manner as in Example 1, followed by a jetting fluid treatment.

The physical properties of the obtained nonwoven fabric were as follows, and the tensile strength was particularly low.

Tensile strength (MD/CD): 0.810.7
kg/c+r+tear strength (8 ID/CD):
1.4/1.2 kg Peeling strength: 0.
31 kg/cm Flexibility Q (D-CD average): 36m
When the nonwoven fabric of Comparative Example 2 was observed using a scanning electron microscope, it was found that the splittable conjugate fibers were not split sufficiently, and many undivided conjugate fibers were observed.

Example 2 The same splittable conjugate fibers used in Example 1 were crimped into short fibers with a fiber length of 10 mm (L/D was 0.98
X103) was obtained. The short fibers were dispersed in water to form a web of 30 g/rd using a wet papermaking method, and subjected to high-pressure jetting treatment (water pressure 25 kg/ad) in the same manner as in Example 1 to obtain an ultrafine fiber nonwoven fabric. This nonwoven fabric has excellent drapability, and
0g/rd, has a thin basis weight and has excellent covering properties, so the interlining obtained by dot processing of low melting point adhesive nylon resin has excellent interlining suitability without resin seepage. there were. The physical properties of the obtained nonwoven fabric are shown below.

Tensile strength (N mountain/CD): 1.6/1.3
kg/cm tear strength (auxiliary/CD): 0.81
0.5 kg Flexibility (8 ID-CD average): 22
11I111 Example 3 Polyethylene terephthalate was used as the first component, polypropylene was used as the second component, and 1.5 denier splittable conjugate fiber having a cross section similar to that shown in FIG. 1(A) was prepared at a ratio of 8-2 (volume ratio). I got it. After crimping (10 crimps/inch), cut into composite staple fibers with a fiber length of 12 strokes (L/D is 0).
．． 98X]03) was obtained. A web of 300 g/po was formed from the short fibers using the cart air lay method, and a web of 300 g/po was formed using a nozzle diameter of 0.
2- Column flow treatment was carried out using a nozzle pitch of 5, a nozzle row number of 18, a papermaking jet nozzle interval of 30 mm, a nozzle header rotation speed of 150 rprn, and a sheet speed of 5 m/min. The physical properties were as follows.

Tensile strength (!i(D/CD):]4.5/13.
8 kg/cm tear strength (MD/CD): 10
．． 4/10.1 kg delamination strength ・2.
210 g/country This intertwined sheet contains polytetramethylene glycol as the polyol component and P as the isocyanate component.

It was impregnated with a 15% dimethylformamide solution of P'-diphenylmethane diisocyanate and polyurethane using ethylene glycol as a chain extender, squeezed to a squeezing rate of 300%, and coagulated in water.

After drying, one side of the obtained impregnated sheet was puffed using a belt sander equipped with 320 mesh emery paper. Next, the ground surface was heated and pressed using a calender roll with a surface temperature of 150°C.

The puffed and heat-pressed surface was coated with a gravure roll (30% dimethylformamide consisting of dipolyethylene acylate, P,P'-diphenylmethane diisocyanate, and ethylene glycol, coagulated in water, and then dried). Furthermore, a 40% solution of polyethylene glycol, P, P'-diphenylmethane diisocyanate, and ethylene diamine in a mixed solvent of methyl ethyl ketone and isopropyl alcohol was coated on this surface using a gravure roll, and the solvent was dried and removed at 130°C. The resulting silver-like sheet material has a polyurethane coating layer with extremely good surface smoothness, excellent flexibility in texture, and physical properties as shown below, making it suitable for use in sports shoes, for example. It had sufficient strength to the extent that it could be obtained.

Tensile strength (MD/CD) ・20.8/20.
2kg/cm tear strength (song/CD): 1
0.8/10.5kg Flexibility (curve/CD average) Near 4M Example 4 A web of 80 g/cnr was formed from the same splittable conjugate staple fibers as used in Example 3 in the same manner.

This was carried out in the same manner as in Example 3 at a water pressure of 40 kg/al.
High-pressure jetting treatment was performed at a net speed of 20 m/min to obtain an ultrafine fiber nonwoven fabric. The physical properties of this nonwoven fabric were as follows.

Tensile strength (MD/CD): 4.8/4.2
kg/ac tear strength (MD/CD): 2.7
/2.3 kg Peeling strength: 2. Okg
/cm Flexibility (MD-CD average): 32 mm The surface of this nonwoven fabric was coated with polyurethane (concentration 30%) dissolved in polyether formamide using a doctor knife in an amount of 45 g/rrr. The resulting coated product has an extremely soft texture because it is a non-woven fabric or has no binder, and the folds on the surface of the polyurethane film are fine and have a natural and luxurious feel, similar to the silver surface of natural leather. Met. Furthermore, since the interlayer peeling strength is sufficiently strong, it was confirmed that there would be no damage such as peeling during use, even when used as a material for upholstery, for example.

Example 5 10 cm of uncrimped short fibers (L/D is 1.OX 103) of the same splittable composite fiber used in Example 1 and short fibers of 1 denier, 8 strand rayon fiber were wet-processed in a ratio of 7:3. A web of 55 g/rd was formed by the method. In the same manner as in Example 1, high-pressure water jet treatment at a water pressure of 35 kg/cut was performed. The physical properties were as follows. This nonwoven fabric has the antistatic and hygroscopic properties of cellulose, and the wipeability and lint-free properties of ultrafine fibers, and is suitable for wiping cloths for industrial electronics, liners for floppy disks, and the like.

Tensile strength (MD/CD): 4.2/3.8
kg/cm tear strength (MD/CD): 2.1
/2. Okg delamination strength: 1.2k
g/cm flexibility (MD-CD average): 32 mm Example 6 The web used in Example 5 was placed on a 14-mesh wire gauze and subjected to high-pressure jetting treatment under the same conditions as in Example 5. Since the obtained nonwoven fabric had a perforated weave pattern, its wiping properties were further improved, and it had the ability to withstand repeated washing 20 times, making it suitable as a wiping cloth with wash resistance.

The physical properties are shown below.

Tensile strength (+14D/CD): 3.9/
3.6 kg/cm tear strength (MD/CD):
1.7/1.5kg Flexibility (MD-CD average): 3
3 mm [Effects of the present invention] The high-strength ultrafine nonwoven fabric produced by the production method of the present invention has high strength that could not be obtained with conventional ultrafine nonwoven fabrics, and can be produced at a low cost.

In addition, it has a soft, drapey texture unique to its ultra-fine fibers, and has excellent cover song properties and lint-free properties.

[Brief explanation of drawings]

Figures 1 (A) to (G) are cross-sectional views schematically showing examples of splittable conjugate fibers used in the present invention. , (e.g. polyester), 2--Incompatible thermoplastic polymers (e.g. polyolefins) without mutual adhesive properties. Patent applicant: Asahi Kasei Industries, Ltd.

Claims (2)

[Claims] 1. The fiber length of the splittable composite fiber is 20 mm or less, and the ratio L/D of fiber length L to fiber diameter D is 0.5 × 10^3 to 2 ×
A nonwoven fabric composed of 10^3 of the composite short fibers, which is obtained by splitting the splittable composite staple fibers and has a diameter of 0.8 denier or less, and/or a fiber bundle of the ultrafine single fibers. High-strength ultrafine fiber nonwoven fabric characterized by three-dimensional intertwining of 2. The fiber length of the splittable composite fiber is 20 mm or less, and the ratio L/D of fiber length to fiber diameter D is 0.5 x 10^3 to 2 x 1.
A web is formed from the composite short fibers of 0^3 and subjected to high-speed fluid flow treatment to entangle and split the splittable composite short fibers, resulting in ultrafine single fibers of 0.8 denier or less and/or Alternatively, a method for producing a high-strength ultrafine fiber nonwoven fabric, which comprises three-dimensionally entangling fiber bundles of the fine single fibers.