JPH1161614A - Staple fiber non-woven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bulky staple fiber non-woven fabric good in a touch and having thermal shrinkage characteristics not deviated in the mechanical direction and in the lateral direction. SOLUTION: This staple fiber non-woven fabric comprises one or more kinds of dispersed and accumulated staple fibers having a fiber length of 3-25 mm and a single fiber fineness of 1-100 denier and containing thermal fusible fibers in an amount of at least 10 wt. % as at least one kind of fibers in the stable fibers. The mutual cross points of the staple fibers are fused. The non-woven fabric has a specific volume of 22-170 cm<3> /g and a mechanical direction/lateral direction thermal shrinkage degree ratio of 0.75-1.25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to short fiber nonwoven fabrics.
More specifically, the present invention relates to absorbent articles such as disposable diapers, sanitary napkins, incontinence pads, breast milk pads, and short fiber nonwoven fabrics used for wipers, filters, and the like.

[0002]

2. Description of the Related Art Conventional short fiber non-woven fabric is disclosed in Japanese Patent Publication No. 52-1.
As described in Japanese Patent No. 2830, a nonwoven fabric is known in which heat-fusible conjugate fibers are carded using a carding machine to form a web, and then heat-treated to fuse the intersections of the fibers. However, the non-woven fabric uses short fibers having a relatively long fiber length of about 32 mm or more, and the fibers are arranged in the machine direction by hooking the fibers with a needle cloth. It was hardly oriented in the thickness direction. Therefore, a non-woven fabric which sufficiently contributes to the bulkiness and texture of fibers has not been obtained. In addition, the heat shrinkage of this nonwoven fabric during heat treatment is large only in a specific direction in the machine direction or the width direction. Therefore, when the non-woven fabric is heat-treated again for the purpose of strengthening the heat fusion between the fibers and further increasing the strength of the non-woven fabric, there is a problem that uneven heat shrinkage and the like occur, and the non-woven fabric is curved and wrinkled. In addition, we laminate nonwoven fabric with other nonwoven fabrics and films in various forms,
Unbalanced heat shrinkage or the like occurs in post-processing or the like accompanied by heat treatment, and the laminated nonwoven fabric alone and / or the entire laminate is bent or wrinkled, which is not always satisfactory.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to provide a short-fiber non-woven fabric which is bulky and has a good texture and which solves the above-mentioned problems.
An object of the present invention is to provide a short-fiber nonwoven fabric having uniform heat shrinkage in the machine direction and the width direction.

[0004]

The invention claimed in the present application is as follows. (1) One or more types of short fibers having a fiber length of 3 to 25 mm and a single yarn fineness of 1 to 100 denier are dispersed and deposited,
And at least one of the short fibers is a heat-fusible fiber, the non-woven fabric contains at least 5% by weight of the heat-fusible fiber, and the intersection of the short fibers is fused. The specific volume is 22 to 170 cm ³ / g, and the heat shrinkage ratio in the machine direction / width direction of the nonwoven fabric is 0.75 to 1.
25 short fiber nonwoven fabric. (2) The short-fiber nonwoven fabric according to (1), wherein the short fiber has a fiber length of 5 to 10 mm. (3) At least one of the short fibers has a crimp number of 3 to 2
3. The short-fiber nonwoven fabric according to the above item 1 or 2, which is a short fiber having 0 crimps / 25 mm crimp. (4) The heat-fusible fiber is a heat-fusible conjugate fiber comprising a low-melting resin having a melting point difference of 15 ° C. or more and a high-melting resin, and the low-melting resin forms at least a part of the fiber surface. The short fiber nonwoven fabric according to any one of items 1 to 3. (5) The short-fiber nonwoven fabric according to any one of (1) to (3) above, wherein the heat-fusible fiber is an eccentric sheath-core composite fiber having high-density polyethylene as a sheath component and polypropylene as a core. (6) The heat-fusible fiber has polyolefin as a sheath component,
4. The short-fiber nonwoven fabric according to any one of the above items 1 to 3, which is an eccentric sheath-core type composite fiber having polyethylene terephthalate as a core component. (7) An absorbent article using the short-fiber nonwoven fabric according to any one of (1) to (6).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The short fibers used in the short fiber nonwoven fabric of the present invention include fibrous fibers such as pulp, cotton, rayon acetate and the like, and synthetic fibers such as nylon, polyester, acrylic, polyethylene and polypropylene. Among the synthetic fibers, heat-fusible fibers such as heat-fusible single fibers and / or heat-fusible conjugate fibers are preferred because the intersections of the fibers are fused by heat treatment for forming a nonwoven fabric after web formation. used. The short fiber nonwoven fabric of the present invention has a heat-fusible fiber of 5 to 10
0% by weight and 95 to 0% by weight of other fibers. However, the content of the heat-fusible fiber varies depending on the use. Specifically, when the pulp is mixed with a liquid absorbent such as a disposable diaper, the proportion of the heat-fusible fiber is 5 to 50% by weight, preferably 6% by weight. -30% by weight, more preferably 7-25% by weight. When mixed with high melting point fiber such as rayon for wiper and filter applications, the ratio of heat fusible fiber is 20%.
-100% by weight, preferably 25-100% by weight, more preferably 30-100% by weight.

The short fiber has a fiber length of 3 to 25 mm.
This fiber length is preferably 3 to 15 mm, more preferably 5 to 10 mm. If the fiber length is less than 3 mm, the strength of the nonwoven fabric is low, and the fibers easily fall off. If the fiber length exceeds 25 mm, it is difficult to produce a uniform web because the fibers are entangled with each other before passing through the screen when forming the web.

The single fiber fineness of the short fibers is 1 to 100 denier. The single yarn fineness is preferably from 1.2 to 35 denier.
And more preferably 1.5 to 20 denier. If the single yarn fineness is less than 1 denier, the fiber opening property is deteriorated,
When the web is formed, the web is entangled in the screen, and it is difficult to form a uniform web. In addition, the obtained non-woven fabric has a large amount of short fibers in a bundle, resulting in poor texture. If the single yarn fineness exceeds 100 denier, the texture of the nonwoven fabric becomes hard. Further, a uniform nonwoven fabric cannot be obtained.

The short fiber nonwoven fabric of the present invention has a specific volume of 22 to 1
70 cm ³ / g, preferably 25 to 160 cm ³
/ G, more preferably 28 to 150 cm ³ / g. When the specific volume is less than 22 cm ³ / g, the hand becomes hard, which is not preferable. On the other hand, when the specific volume exceeds 170 cm ³ / g, the strength of the nonwoven fabric is undesirably reduced.

The short fiber nonwoven fabric of the present invention has a heat shrinkage ratio in the machine direction / width direction of 0.75 to 1.25. This heat shrinkage ratio is preferably 0.80 to 1.20. When the heat shrinkage ratio is less than 0.75 or more than 1.25,
Heat treatment such as post-processing of the nonwoven fabric causes a large amount of heat shrinkage in the longitudinal or lateral direction, and the so-called non-uniform non-uniform heat shrinkage or uneven heat shrinkage of the nonwoven fabric undesirably causes bending or wrinkles. The heat shrinkage ratio is the ratio of the heat shrinkage in the machine direction / width direction after the short fiber nonwoven fabric is heat-treated at 145 ° C. for 5 minutes as described later.

When the short fibers used in the short-fiber nonwoven fabric of the present invention are heat-fusible fibers, regular heat-fusible fibers spun by mixing the following thermoplastic resins alone or two or more kinds thereof can be used. . Further, so-called heat-fusible conjugate fibers using the following thermoplastic resin or the like as a component forming at least a part of the fiber surface of the low melting thermoplastic resin and using a high melting thermoplastic resin as another component can be used. As thermoplastic resins, polyolefins such as polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, crystalline propylene copolymers of propylene and other α-olefins, polyamides, polyethylene terephthalate -, Polybutylene terephthalate,
Examples thereof include low-melting polyesters obtained by copolymerizing diol and terephthalic acid / isophthalic acid, polyesters such as polyester elastomers, and fluorine resins.

In the case of a composite fiber, the combination of the low melting point resin and the high melting point resin may be any combination of resins having a difference in melting point of 15 ° C. or more. Examples of such a resin combination include high-density polyethylene / polypropylene, low-density polyethylene / polypropylene, propylene / ethylene / butene-1 crystalline copolymer / polypropylene, high-density polyethylene / polyethylene terephthalate, and nylon-polyethylene. 6 / Nylon-66, low melting point polyester / polyethylene terephthalate, polypropylene / polyethylene terephthalate, polyvinylidene fluoride / polyethylene terephthalate, mixture of linear low density polyethylene and high density polyethylene / high density polyethylene Examples thereof include a mixture of polypropylene. With this combination,
If heat treatment is performed at a temperature higher than the melting point of the low melting point resin and lower than the melting point of the high melting point resin, the low melting point component of the composite fiber is melted, the intersection of the fibers is fused, and the high melting point component remains as it is. Can form a short-fiber non-woven fabric having a microstructure.

The form of the heat-fusible conjugate fiber may be a parallel type, a sheath-core type, an eccentric sheath-core type, a multilayer type having three or more layers, a hollow parallel type, a hollow sheath-core type, a modified sheath-core type, a sea-island type, and the like. In addition, any composite fiber having a structure in which the low melting point resin forms at least a part of the fiber surface may be used. The most preferred of these composite fibers are high density polyethylene, linear low density polyethylene, propylene
A parallel type, a sheath-core type, an eccentric sheath-core type, etc., in which any one selected from ethylene-butene-1 crystalline copolymer is used as a low melting point resin and polypropylene or polyethylene terephthalate is used as a high melting point resin. It is a composite fiber.

[0013] In addition, a crimp does not have to be used, and a strand chop may be used. Further, any of those having a two-dimensional crimp such as a zigzag type and a three-dimensional crimp such as a spiral type or an ohm type can be used. In the case of a conjugate fiber having a three-dimensional crimp, a bulky nonwoven fabric is obtained. The bulkiness of the web depends on the crimps of the heat-fusible short fibers and other short fibers to be used, and it is particularly preferable that the fibers have a spiral crimp of 3 to 20 ridges / 25 mm. More preferably, it is a fiber having a spiral crimp of 4 to 15 ridges / 25 mm, more preferably 4 to 12 ridges / 25 mm.

The composite ratio of the low melting point resin to the high melting point resin in the composite fiber is 10 to 90% by weight for the low melting point resin and 90 to 10% by weight for the high melting point resin. Preferably, the low melting point resin is 30 to 70% by weight and the high melting point resin is 70 to 30% by weight. When the low melting point resin is less than 10% by weight, the strength of the nonwoven fabric is reduced due to insufficient heat fusion. On the other hand, if the content of the low melting point resin exceeds 90% by weight, the heat-fusing behavior similar to that of the regular heat-fusible fiber is exhibited, so that the property that the high melting point component of the composite fiber retains the fibrous form is reduced. . Of course, the fiber shape can be maintained by setting the heat treatment conditions, so that regular fibers may be used.

The short-fiber nonwoven fabric of the present invention uses the above-mentioned heat-fusible fiber and the like, and forms a web by using a so-called short-fiber-dispersion drop-type web manufacturing apparatus that disperses the fiber and causes it to descend. Further, it is obtained by heat-treating at a temperature higher than the heat fusion temperature by a heat treatment machine to fuse the intersections of the fibers. As the web production apparatus as described above, for example, a box-type sieve-type apparatus that vibrates in any of front and rear, left and right, up and down, horizontal circular, and the like and disperses and drops short fibers from a sieve eye can be used.
In addition, a net-shaped metal porous plate is formed into a cylindrical shape and has a short fiber inlet on its side surface, and a net-shaped cylindrical body type device which rotates and disperses and drops short fibers from its eyes can be used. .

Using the above-mentioned web producing apparatus, the short fibers are dispersed and dropped from the mesh of the sieve, and collected so as to be deposited on a web collecting apparatus such as a net conveyer arranged under the short fibers. Further, the nonwoven fabric of the present invention is heated by using a heat treatment machine to a temperature higher than the heat fusion temperature to fuse the intersections of the short fibers. The web heat treatment machine is
Type heat treatment machine, embossing roll type heat treatment machine, flat type
And a combination of any of them. When an air-slurry type heat treatment machine is used, a bulky nonwoven fabric is obtained. When an embossing roll type heat treatment machine is used, a nonwoven fabric having a relatively high fiber density of the nonwoven fabric and having an uneven surface is obtained. When an embossing roll type heat treatment machine is used, the embossing roll preferably has a convex area of about 10 to 30%. If the convex area is less than 10%, a nonwoven fabric having a high strength cannot be obtained. On the other hand, if it exceeds 30%, the texture of the nonwoven fabric becomes hard and a bulky nonwoven fabric cannot be obtained.

The basis weight of the short fiber nonwoven fabric of the present invention is not limited. However, those having a basis weight of about 8 to 1000 g / m ² are preferably used. Approximately 8 to 60 g / m ² when the nonwoven fabric is used as a surface material of a liquid absorbent article such as a disposable diaper, and approximately 10 to 400 g when the nonwoven fabric is used as a filler for wipers or clothes.
/ M ^2, filters - a case about 15~1000g / m ² of.

The absorbent article of the present invention is an article in which the short fiber nonwoven fabric is used as a material for a liquid absorbent article such as a disposable diaper. Specific examples of the absorbent article include a newborn paper diaper that absorbs urine and loose stool, an infant paper diaper that mainly absorbs urine, sanitary napkins, wound pats, sweat-absorbing pats, liquid-absorbing wipers, liquid-absorbing sheets, and the like. Can be exemplified. In short, any article that absorbs the liquid may be used.

A backsheet for preventing liquid leakage of a film or the like;
In the case of an absorbent article such as a paper diaper or the like made of a liquid absorbent made of pulp or a polymer water-absorbing agent, or a liquid-permeable porous sheet such as a porous film, the short fiber nonwoven fabric is used as a surface material. The used thing can be illustrated. Such a disposable diaper has a good texture, and also has a function of permeating loose stool as well as newborn urine into the nonwoven fabric. In the above-mentioned disposable diaper, a short-fiber non-woven fabric in which heat-fusible fibers and hydrophilic fibers such as rayon are mixed and a short-fiber non-woven fabric consisting of only heat-fusible fibers are laminated to form a multilayer structure. Examples of such materials include those using a nonwoven fabric layer made of only heat-fusible fibers as a surface material on the skin side. This disposable diaper has urine,
There is a function that loose stools and the like are absorbed into the inside more quickly. In addition, a sheet having a composite structure in which the above-mentioned short fiber non-woven fabric is laminated on the outside of a liquid leakage preventing back sheet such as a film.
The disposable diaper using the sheet as a backsheet has a very good texture. Further, the short fiber non-woven fabric as described above is used in the vicinity of the body part and / or the leg part of the disposable diaper, and the other part is made of a cardboard heat-sealed non-woven fabric. Becomes

The nonwoven fabric of the present invention may be used alone or in various other parts, such as other nonwoven fabrics, liquid absorbers, cloths, films,
It can be used in various composite forms in combination with wood boards, metal boards, etc. The short-fiber nonwoven fabric of the present invention can be used as wipers for furniture, cars, etc. by adhering various oils. For example, a nonwoven fabric having a composite structure in which an ultrafine fiber nonwoven fabric having a fiber diameter of about 10 μm or less and a short fiber nonwoven fabric are laminated and both layers are fused may be used. The nonwoven fabric of this composite structure can be used for wipers, disposable diapers and the like. Further, a short-fiber nonwoven fabric can be wound or wound with heating to form a cylindrical filter in which the layers are fused. It is also possible to fold the short fibers, or to form a filter formed into a tubular shape after the folds.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. The physical properties and the like of the short-fiber nonwoven fabric in this example and the like were measured by the methods described below.

Nonwoven fabric strength: The tensile strength in the width direction of the nonwoven fabric was measured using a tensile strength tester, and the strength was defined as the tensile strength. The measurement conditions were such that a sample having a width of 5 cm (machine direction) and a length of 15 cm (width direction) was
The measurement was performed under the conditions of 0 cm and a pulling speed of 10 cm / min.
Unit kg / 5cm.

Specific volume: Measure the basis weight and thickness of the nonwoven fabric,
The specific volume was calculated. Unit cm ³ / g.

Heat shrinkage ratio: Using a hot air circulation type dryer, a nonwoven fabric having a size of 25 cm × 25 cm
C. for 5 minutes, and heat shrinkage (MD)
%) And the heat shrinkage in the width direction (CD%) of the nonwoven fabric were measured. MD% / CD% was defined as the heat shrinkage ratio.

Texture: The texture of the nonwoven fabric was evaluated by five panelists from the viewpoint of flexibility and uniformity by judging the presence or absence of spots and wrinkles. When three or more persons evaluated that the nonwoven fabric was insufficient in flexibility or the nonwoven fabric was non-uniform, the texture was judged to be poor, and the others were judged to be good.

Example 1 A nonwoven fabric was manufactured using a polyolefin-based heat-fusible conjugate fiber. The heat-fusible conjugate fiber used had a sheath component of MI = 17.
(JIS-K7210 condition 4), high-density polyethylene (HDPE) having a melting point of 132 ° C. and a core component having an MFR = 18
(Condition 14 of JIS-K7210), made of polypropylene (PP) having a melting point of 164 ° C, and a composite ratio of 50/50% by weight
In a sheath-core type composite fiber. This composite fiber has a single yarn fineness of 2.1 denier, a fiber length of 10 mm, and a number of crimps of 12 ridges / 25.
It was a short fiber having a zigzag crimp of mm.

In the web manufacturing apparatus used, a net-shaped metal porous plate is formed into a cylindrical shape, has a short fiber inlet on its side, rotates, and disperses and drops the short fibers from its eyes. It was a cylindrical type device. The opened short fibers are supplied from the short fiber input port, and the short fibers are dispersed and deposited on a net conveyor from the eyes to form a web in which the short fibers are randomly oriented, and the web is further downstream. Using a through-air type heat treatment machine provided in the process, a heat treatment was performed at a temperature of 148 ° C. for 10 seconds to obtain a nonwoven fabric where the intersections of short fibers were fused.

The short fiber nonwoven fabric has a basis weight of 20 g / m ² , a strength in the width direction of 1.63 kg / 5 cm, and a specific volume of 102 cm ^3.
/ G, the heat shrinkage ratio was 1.20, and the texture was good.
Table 1 shows data such as physical properties of short fibers and nonwoven fabrics.

Examples 2, 3, 4, 5 A nonwoven fabric was produced using polyolefin-based heat-fusible composite fibers. The heat-fusible conjugate fiber used had a sheath component of MI = 17.
(JIS-K7210 condition 4), high-density polyethylene (HDPE) having a melting point of 132 ° C., and a core component having MFR = 22
(Condition 14 of JIS-K7210), made of polypropylene (PP) having a melting point of 164 ° C., and a composite ratio of 40/60% by weight
Eccentric sheath-core type composite fiber. This conjugate fiber was a short fiber having a three-dimensional crimp in which a spiral having a single yarn fineness of 3.2 denier and a number of crimps of 8 threads / 25 mm and an ohm-type crimp were mixed. The fiber length was 5 mm (Example 2), 10 mm (Example 3), 20 mm (Example 4), and 25 mm (Example 5).

Using each short fiber, a web was produced and the web was heat-treated in the same manner as in Example 1 to obtain four kinds of nonwoven fabrics where the intersections of the short fibers were fused. However, the heat treatment conditions were a temperature of 150 ° C. and a time of 5 seconds.

The short fiber nonwoven fabric obtained in Example 2 has a basis weight of 25 g / m ² , a width direction strength of 1.38 kg / 5 cm, a specific volume of 137 cm ³ / g, a heat shrinkage ratio of 0.98, and a good texture. , Table 1 shows data on the physical properties of the short fibers and nonwoven fabrics of Examples 2, 3, 4, and 5.

Comparative Example 1 The same polyolefin-based heat-fusible conjugate fiber as in Examples 2 to 5 was used except that the fiber length was 32 mm. An attempt was made to produce a fibrous nonwoven fabric. However, in the process of dispersing staple fibers on a net conveyor and allowing them to fall down and producing a web in which the staple fibers are randomly oriented, the staple fibers are entangled inside the net-shaped cylindrical body, and the staple fibers are smoothly formed from the eyes. Thus, it was impossible to produce a target web having a basis weight of 25 g / m ² . The obtained web had a basis weight of 4 g / m ² , and had a severe basis spot. The heat treatment of the web was discontinued. Table 1 shows data of short fibers and the like.

Comparative Example 2 The same polyolefin fusible conjugate fiber having a fiber length of 32 mm as in Comparative Example 1 was produced using a carding machine to produce a web in which the fibers were oriented in the machine direction. This web was used in the first embodiment.
The same heat treatment was performed to obtain a nonwoven fabric in which the intersections of the short fibers were fused.
The heat treatment conditions at this time were a temperature of 150 ° C. and a time of 5 seconds.

This short fiber nonwoven fabric has a basis weight of 25 g / m ² ,
0.68kg / 5cm in width direction strength, 68cm in specific volume
³ / g, the heat shrinkage ratio was 2.31, and the texture was poor. This nonwoven fabric had low strength in the width direction and was inferior in bulkiness. The texture was slightly harder than the nonwoven fabrics described in Examples 2 to 5. Table 1 shows data such as physical properties of short fibers and nonwoven fabrics.

Example 6 A nonwoven fabric was produced using a polyolefin / polyester heat-fusible conjugate fiber. The heat-fusible conjugate fiber used had a sheath component of MI = 20 (JIS-K7210 condition 4) and a melting point of 1.
Linear low-density polyethylene (LLDPE) at 25 ° C., with a core component of polyethylene terephthalate (PET) having an intrinsic viscosity of 0.68 dl / g, and a composite ratio of 40/60% by weight
In a sheath-core type composite fiber. This composite fiber has a single yarn fineness of 7.8 denier, a fiber length of 10 mm, and a crimp number of 0 ridges / 25 m.
m short fibers.

Using the short fibers, a web was produced and the web was heat-treated in the same manner as in Example 1 to obtain a nonwoven fabric in which the intersections of the short fibers were fused. However, the heat treatment condition is temperature 14
The temperature was 8 ° C. for 18 seconds. The obtained short-fiber nonwoven fabric has a basis weight of 85 g / m ² and a width direction strength of 5.38 kg / 5 c.
m, specific volume is 32 cm ³ / g, heat shrinkage ratio is 1.03,
The texture was good. Data on physical properties of short fibers and non-woven fabrics
The data are shown in Table 1.

Example 7 A non-woven fabric was produced using a polyolefin-based heat-fusible conjugate fiber. The first component of the heat-fusible conjugate fiber used was MFR =
18 (JIS-K7210 condition 14), propylene / ethylene / butene 1 copolymer having a melting point of 136 ° C. (Co-P
P), the second component is MFR = 22 (JIS-K7210)
Condition 14), polypropylene (PP) having a melting point of 165 ° C.
And a parallel type composite fiber having a composite ratio of 50/50% by weight. The composite fiber was a short fiber having a spiral crimp with a single yarn fineness of 1.8 denier, a fiber length of 8 mm, and a number of crimps of 6 ridges / 25 mm.

Using the short fibers, a web was produced and the web was heat-treated in the same manner as in Example 1 to obtain a nonwoven fabric in which the intersections of the short fibers were fused. However, the heat treatment condition is temperature 14
The temperature was 5 ° C. for 12 seconds. The obtained short fiber nonwoven fabric has a basis weight of 25 g / m ² and a strength in the width direction of 1.16 kg / 5 c.
m, specific volume is 129 cm ³ / g, heat shrinkage ratio is 1.1
0, the texture was good. Table 1 shows data such as physical properties of short fibers and nonwoven fabrics.

Example 8 A nonwoven fabric was produced using a polyolefin-based heat-fusible conjugate fiber. The heat-fusible conjugate fiber used had a sheath component of MI = 17.
(JIS-K7210 condition 4), high-density polyethylene (HDPE) having a melting point of 132 ° C. and a core component having an MFR = 18
(Condition 14 of JIS-K7210), a sheath-core composite fiber composed of polypropylene (PP) having a melting point of 166 ° C. and having a composite ratio of 60/40% by weight. This conjugate fiber has a single yarn fineness of 2.5 denier, a fiber length of 8 mm and a crimp number of 0 ridges / 25 mm.
Short fibers.

Using the short fibers, a web was produced and the web was heat-treated in the same manner as in Example 1 to obtain a nonwoven fabric in which the intersections of the short fibers were fused. However, the heat treatment condition is temperature 14
5 ° C., time 5 seconds. The obtained short fiber nonwoven fabric has a basis weight of 25 g / m ² and a strength in the width direction of 3.07 kg / 5 c.
m, specific volume 44 cm ³ / g, heat shrinkage ratio 1.05,
The texture was good. Data on physical properties of short fibers and non-woven fabrics
The data are shown in Table 1.

Example 9 A nonwoven fabric was produced by mixing two types of short fibers. The short fibers used were the heat-fusible conjugate fibers described in Example 8 and a single yarn fineness of 1.5 denier, a fiber length of 5 mm, and a crimp number of 0 ridges / 25 m.
m rayon short fibers were used. 10% by weight of the heat-fusible conjugate fiber and 90% by weight of the number of crimps / 25 mm rayon were mixed, and the web was produced and the web was heat-treated in the same manner as in Example 1 to obtain the intersection of the short fibers. Was obtained.
However, the heat treatment conditions were a temperature of 145 ° C. and a time of 5 seconds.
The obtained short fiber nonwoven fabric has a basis weight of 25 g / m ² , a width direction strength of 0.51 kg / 5 cm, a specific volume of 89 cm ³ / g,
The heat shrinkage ratio was 0.97 and the texture was good. Table 1 shows data such as physical properties of short fibers and nonwoven fabrics.

Comparative Example 3 Two types of short fibers were mixed and a carding machine was used to produce a web in which the short fibers were oriented in the machine direction. The short fibers used were the polyolefin-based conjugate fiber having a fiber length of 32 mm described in Comparative Example 1, a single yarn fineness of 1.5 denier, and a fiber length of 51 m.
m, a rayon short fiber having a zigzag crimp of 14 crimps / 25 mm. The mixing ratio was 10% by weight of polyolefin-based composite fibers and 90% by weight of rayon short fibers. A web was manufactured from this mixed web using a carding machine in the same manner as in Comparative Example 2, and the web was heat-treated to obtain a nonwoven fabric in which the intersections of short fibers were fused. The heat treatment condition at this time is temperature 15
0 ° C., time 15 seconds.

This short fiber nonwoven fabric has a basis weight of 25 g / m ² ,
0.30kg / 5cm in width direction strength, 58cm in specific volume
³ / g, the heat shrinkage ratio was 1.48, and the texture was poor. This nonwoven fabric had low strength in the width direction and low bulk. The texture was harder than the nonwoven fabric described in Examples 2 to 5. Data on physical properties of short fibers and non-woven fabrics
The data are shown in Table 1.

Example 10 Using a commercially available disposable diaper, a novel disposable diaper using the short-fiber nonwoven fabric described in the above Example 1 only with the surface material of the disposable diaper was manufactured. This commercially available disposable diaper uses a polyethylene sheet as a backing material for preventing liquid leakage, a liquid absorbing material comprising pulp and a polymer water-absorbing agent wrapped in a tissue above the backing material, and a surface material above the backing material. Used was a spunbonded polypropylene long-fiber nonwoven fabric.
The surface material was a non-woven fabric having a specific volume of 20 cm ³ / g and thermocompression-bonded by an embossing method. Only the surface material was removed from the disposable diaper while being cut off with a knife. In place of the removed surface material, the short fiber nonwoven fabric obtained in Example 1 was laminated, the peripheral portion of the disposable diaper was thermocompressed with a width of 3 mm, and the back material and the obverse surface were thermocompressed to obtain the disposable diaper of the present invention. . This disposable diaper had good bulkiness and good texture. It was also confirmed that the urine had good absorbability and also had good stool absorbency. This disposable diaper can be preferably used as a diaper for a newborn baby.

[0045]

[Table 1]

[0046]

The short-fiber nonwoven fabric of the present invention is excellent in bulkiness and texture because the fibers are randomly oriented in the machine direction, width direction, thickness direction and the like of the nonwoven fabric. Further, the non-woven fabric has a heat shrinkage property that does not shrink in one direction only in either the machine direction or the width direction and shrinks evenly in any direction. For this reason, this nonwoven fabric is excellent in uniformity without wrinkling or bending when heat-treated in a post-process or the like.

Claims (7)

[Claims] 1. A fiber length of 3 to 25 mm and a single yarn fineness of 1 to 10.
One or more short fibers of 0 denier are dispersed and deposited, and at least one of the short fibers is a heat fusible fiber, and the heat fusible fiber is at least 5% by weight. A non-woven fabric having a specific volume of 22 to 170 cm ³ / g and a heat shrinkage ratio of 0.2 in the machine direction / width direction of the non-woven fabric. 75
1.25 short fiber nonwoven fabric. 2. The short-fiber nonwoven fabric according to claim 1, wherein the short fibers have a fiber length of 5 to 10 mm. 3. The short-fiber nonwoven fabric according to claim 1, wherein at least one of the short fibers is a short fiber having a crimp number of 3 to 20 peaks / 25 mm. 4. A heat-fusible conjugate fiber comprising a low-melting resin having a melting point difference of 15 ° C. or more and a high-melting resin, wherein the low-melting resin forms at least a part of the fiber surface. The short fiber nonwoven fabric according to any one of claims 1 to 3. 5. The short-fiber nonwoven fabric according to any one of claims 1 to 3, wherein the heat-fusible fiber is an eccentric sheath-core composite fiber having high-density polyethylene as a sheath component and polypropylene as a core. 6. The short-fiber nonwoven fabric according to claim 1, wherein the heat-fusible fiber is an eccentric sheath-core composite fiber having polyolefin as a sheath component and polyethylene terephthalate as a core component. 7. An absorbent article using the short-fiber nonwoven fabric according to claim 1.