JPH0424263A - Nonwoven fabric, production thereof and absorbing article - Google Patents

Abstract

PURPOSE:To obtain nonwoven fabric surely permeating excrement, certainly preventing leakage, having performance of suppressing return of humor, excellent touch, etc., by integrating two fiber webs containing thermoplastic fibers by a specific method. CONSTITUTION:First, a first fiber web 11'' containing a thermoplastic fibers is placed on an air-permeable conveyor 51 having unevenness. When the web is transported, a gas is sprayed upon the surface of the web 11'' from a device 53 to form uneven parts on the web 11''. Then a second fiber web 12' containing thermoplastic fibers is laid under the uneven parts of the web 11'', both the webs are heat-treated by a heat-treating part 120 and integrated t give nonwoven fabric 10 comprising an upper layer fiber web 11 which has wholly dispersed protruded parts 11A1 and dented parts 11A2 at the central part 11A wherein the dented parts 11A2 have a lower fiber aggregation density than the protruded parts 11A1 and a lower layer fiber web 12 which has uniform fiber aggregation density and exists at least at positions of the protruded and the dented parts 11A1 and 11A2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a nonwoven fabric, a method for producing the same, an absorbent article,
More specifically, the present invention relates to a nonwoven fabric having irregularities suitable as a surface material for absorbent articles such as disposable diapers and sanitary napkins, a method for producing the same, and an absorbent article using the nonwoven fabric as a surface material.

[Prior Art] One of the challenges of absorbent articles such as disposable diapers and sanitary napkins is to suppress or prevent leakage of body fluids such as urine, loose stool, and menstrual blood from the absorbent article.

For this purpose, the members constituting the absorbent article, that is, the surface material,
The absorbent body, backing material, etc. are each designed with ingenuity to suppress or prevent leakage of body fluids.

Nonwoven fabrics are often used as surface materials for boat fishing, and these nonwoven fabrics are often made of hydrophilic thermoplastic fibers to improve absorption of body fluids. Also,
In order to prevent seepage and leakage of body fluids, attempts have been made to make the site or surrounding areas of nonwoven fabrics, which are surface materials of sanitary products, hydrophobic.

On the other hand, high viscosity body fluids such as loose stools and highly viscous menstrual blood have poor permeability through normal non-woven fabrics, and before they are absorbed by the internal absorbent material, they flow over the surface of the non-woven fabric, staining clothing and sometimes even exposing the skin. It may cause discomfort when touched.

Conventional countermeasures against these problems include, for example, a method of perforating nonwoven fabric with pins, needles, etc., and a method of entangling the web with high-speed water jets to form a perforated or mesh shape (Japanese Patent Publication No. 62-62).
175, No. 62-28219), methods have also been proposed in which the basis weight of the nonwoven fabric is reduced or the distance between fibers is increased using thick denier fibers.

[Problem to be solved by the invention]

However, conventional nonwoven fabrics and methods for producing the same have the following problems.

In other words, non-woven fabrics that have been perforated with bottles, needles, etc. have protrusions around the pores on the surface, making them uncomfortable to the touch, and the perforations lack stability in form. , fluffing is likely to occur, bulkiness cannot be obtained unless the basis weight is increased, and what's more, the fiber treatment agent falls off due to high-speed water flow and those made of thermoplastic fibers become hydrophobic. There was a risk. Also, sufficient confounding,
In order to provide perforations, it is not possible to increase the machining speed, and furthermore, there are problems in that the water flow scatters around the manufacturing equipment, making it unfavorable for the working environment, and furthermore, it causes rust in the manufacturing equipment. Furthermore, with mesh-like nonwoven fabrics, body fluids absorbed into the absorbent material return to a large extent, and when used as a surface material,
There was also the issue of not being able to obtain a dry feeling. In particular, absorbent bodies are often covered with a backing paper, and in such absorbent bodies, high viscosity body fluids such as soft stool and menstrual blood tend to clog the backing paper. There was a problem that could not be adequately addressed with only one method.

In short, when conventional nonwoven fabrics are used as surface materials,
Although all of them have some degree of permeability to highly viscous body fluids and other excreta, they are not necessarily sufficient in terms of liquid permeability, and the countermeasures against clogging with the mount of the absorbent body are not sufficient, and the The properties required for a surface material, such as performance in suppressing the return of body fluids, bulkiness, and texture such as texture, have not always been satisfied.

Therefore, it is an object of the present invention, when used as a surface material of an absorbent article, to ensure that highly viscous body fluids and other excreta are permeable, to reliably suppress or prevent their leakage, and to retain highly viscous substances. A comprehensively excellent nonwoven fabric that allows low viscosity substances to pass through in a state that allows good absorption into an absorbent body, and also has various properties such as texture required as a surface material, and a method for producing the nonwoven fabric, as well as a method for producing the nonwoven fabric. The objective is to provide an absorbent article that utilizes the various properties of the absorbent material.

[Means to solve the problem]

As a result of various studies on nonwoven fabrics that can prevent the flow of highly viscous liquids and have excellent permeability, and methods for producing the same, the inventors of the present invention have found that by forming irregularities on a fibrous web by a specific means, It has been found that the above object can be achieved by polymerizing different types of fibrous webs onto the web and then thermally fusing the thermoplastic fibers contained in each fibrous web.

The present invention was made based on the above findings, and provides a nonwoven fabric in which an upper layer fibrous web containing thermoplastic fibers and a lower layer fibrous web containing thermoplastic fibers are integrated. The web has convex portions and concave portions dispersed throughout the web at least in the central portion, and the fiber aggregation density in the concave portions is lower than that in the convex portions, and the fiber web in the lower layer is substantially It is an object of the present invention to provide a nonwoven fabric characterized in that the fiber aggregate density is uniform and exists at least at the positions of the uneven portions.

The present invention also provides an absorbent article that includes a surface material that comes into contact with the skin and an absorbent body covered with the surface material, and that absorbs bodily fluids and other excreta, in which the surface material is formed of the nonwoven fabric. The present invention also provides an absorbent article characterized by:

In addition, the present invention provides a manufacturing method suitable for manufacturing the above-mentioned nonwoven fabric, in which a first fiber web containing thermoplastic fibers and a second fiber web containing thermoplastic fibers are respectively formed, and the nonwoven fabric has irregularities. A first fibrous web is placed on a breathable conveyor, and while the fibrous web is being conveyed while being placed, gas is injected onto the surface of the fibrous web to follow the fibrous web into the recessed portion of the breathable conveyor. to form an uneven portion on the fibrous web, and then, after positioning and overlapping the second fibrous web below at least the uneven portion of the first fibrous web, both are heated and the respective thermoplastic The present invention also provides a method for manufacturing the above-mentioned nonwoven fabric, characterized in that the fibers are fused to integrate the two.

[Effect]

According to the absorbent article using the nonwoven fabric of the present invention, it has a good touch when worn, and after being worn, high viscosity body fluids such as soft stool and menstrual blood are reliably permeated at least in the central part, and the permeated high viscosity body fluids are Among them, while the high viscosity substance is held in the lower layer fiber web, the low viscosity substance is allowed to permeate into the absorbent body and smoothly absorbed into the absorbent body, thereby suppressing or preventing the liquid from returning from the absorbent body.

Further, according to the method for producing a nonwoven fabric of the present invention, a first fiber web containing thermoplastic fibers and a second fiber web containing thermoplastic fibers are respectively formed, and the first fiber web is placed on an air permeable conveyor having unevenness. A fibrous web is placed on the fibrous web, and while the fibrous web is being conveyed with the fibrous web placed thereon, gas is injected onto the surface of the fibrous web to cause the fibrous web to follow the concave portions of the breathable conveyor, thereby creating irregularities in the fibrous web. form a section, then
When the second fibrous web is positioned below at least the uneven portion of the first fibrous web and overlapped, and then both are heated, the respective thermoplastic fibers are fused to form at least the uneven portion where the two are integrated. It is possible to produce a nonwoven fabric having a two-layer structure in a section.

[Example] The present invention will be described below based on the example shown in FIGS. 1 to 9. In each figure, FIG. 1 is a partial perspective view conceptually showing one embodiment of the nonwoven fabric of the present invention, and FIG. 2 is a partial perspective view of FIG. 1.
■ Line sectional view, FIG. 3 is a view equivalent to FIG. 1 showing another embodiment of the nonwoven fabric of the present invention, FIG. 4 is a sectional view taken along line IV-IV in FIG. 2,
FIG. 5 is a view equivalent to FIG. 1 showing still another embodiment of the nonwoven fabric of the present invention, FIG. 6 is a Vl-Vl cross section of FIG. 5, and FIG. 7 is a diagram showing a method for manufacturing the nonwoven fabric of the present invention. FIG. 8 is a plan view showing a part of the lower breathable conveyor used in the unevenness forming part of the manufacturing device shown in FIG. 7; FIG. 9 is a side view of the ventilation conveyor shown in FIG. 8.

The nonwoven fabric 10 of this example is formed by integrating an upper layer fibrous web 11 containing thermoplastic fibers and a lower layer fibrous web 12 containing thermoplastic fibers, and is conceptually shown in FIG. As shown, the upper layer fibrous web 11 has convex portions 11A1 and concave portions 11A2 dispersed throughout the central portion 11A thereof. The concave portion 11Az
1 and 2 are expressed as completely open holes, but originally the fiber web is diffused into the surrounding convex portion 11A1 and the fiber aggregate density is low. In other words, the convex portion 11A1 surrounding the concave portion 11A2 has a higher fiber aggregation density, and as a result, the fiber aggregation density of the concave portion 11A is lower than that of the convex portion 11A. . Moreover, in this way, the concave portion 1
The fiber aggregation density in 1A2 becomes low, and the concave portion 11
Preferably, A2 is in a substantially open state as described above. It is preferable that the convex portions 11A1 and the concave portions 11A2 are arranged alternately and regularly as shown in FIG. It is possible to improve the appearance quality of the product. In addition, the preferred pinch of the unevenness is 3 to 20 mm; if the pinch is less than 3 mm, the unevenness is too small and the bulkiness decreases; conversely, the pinch is 20 mm.
If it exceeds the height, the concave and convex portions will be too large and will not only improve the quality of the appearance, but will also cause the concave portion 11A to function as an absorption hole for highly viscous liquid.
The pitch becomes larger, reducing the permeability of highly viscous liquids. In addition, the hole diameter of the above-mentioned hole is φ2~
It is preferable that the diameter of the recessed portion 11 is 6 mm.
The difference in height between the bottom surface of A2 and the bottom surface of the convex portion 11A1 is characterized by h>o, and h>0.5.
ann is more preferred.

On the other hand, both end portions 11B and II adjacent to the central portion 11A
In B, the convex portion 11A1 and the concave portion 11A2 are not formed, and they are formed substantially flat, and the fiber aggregation density is formed to be substantially uniform, so that the texture is improved.

Therefore, the nonwoven fabric 10 of this example has a basis weight of 15 to 40.
g/rd, and the upper layer fibrous web 11
is 9 to 30 g/rrr, and the lower layer fiber web 12 is 6 to 3
1 g/n (preferably. The lower the basis weight,
The bulkiness is low, the roughness is also poor, and the liquid return property is also poor.

Conversely, even if the basis weight is made higher than necessary, it is disadvantageous in terms of cost. Further, the lower layer fiber web 12 has a basis weight of 6 g/n.
(If it is less than 31 g/po, it will be difficult to exhibit high viscosity liquid retention ability, and if it exceeds 31 g/po, no improvement in retention performance will be observed.

Moreover, the fiber aggregation density of the convex part 11A and the concave part 11A2 in the central part 11A of the upper layer fiber web 11 is set at the middle between the top of the convex part 11A1 and the bottom of the concave part 11A2 of the nonwoven fabric 10, Assuming that the fiber web in the portion above the middle is a fiber web belonging to the convex portion 11A, and the fiber web in the portion below the middle is a fiber web belonging to the concave portion 11A2, the fiber aggregate density of the convex portion 11A is: l X ] 0-5 to 8
2×IQ−5 g/mm”. Here, the fiber aggregation density is defined by the following formula and means the average basis weight in a minute area.

Further, the lower layer fibrous web 12 retains the high viscosity of the high viscosity liquid that has permeated in the layer where the convex portions 11A1 and the concave portions 11A2 of the upper layer fibrous web 11 are dispersed. It functions as a retention layer that allows low viscosity liquid to be absorbed into the absorbent body. The fiber web 12 of the lower layer preferably has an average inter-fiber distance of 60 to 300 μm, more preferably 100 to 250 μm, which is necessary for exhibiting the above function. If the diameter is smaller than 60 μm, the ability to draw in high viscosity liquids will be significantly reduced, and if it is larger than 300 μm, the ability to draw in high viscosity liquids will be good, but on the other hand, the high fineness fibers in the lower layer will protrude from the openings in the concave portion of the upper layer] IA2. There is a risk that the tactile sensation may be impaired.
Moreover, there is a possibility that the strength of the nonwoven fabric as a whole may be reduced. Here, the average interfiber distance is calculated from the thickness of the nonwoven fabric, the basis weight, and the fiber fineness of the constituent web, and is defined by the following formula.

t: Thickness of non-woven fabric (0 rin) W: basis weight of non-woven fabric (g/n() d: fineness of fibers constituting the fiber web (denier) As is clear from the above formula, the average inter-fiber distance is Liquid permeability can be increased by increasing d.

The thermoplastic fibers forming the fiber webs of the upper and lower layers include, for example, polyethylene terephthalate (melting point 255°C), polybutylene terephthalate (melting point 255°C),
Polyester type (melting point 215°C), polyethylene (
melting point 130°C), polypropylene (melting point 165°C)
Polyolefins such as nylon-6 (melting point 220°C
), polyamide-based fibers such as nylon-66 (melting point 260°C), and modified polymers thereof.

In addition, each of the above fiber webs contains 50% by weight of thermoplastic fibers.
It is preferable that the thermoplastic fiber contains the above amount, and it is also preferable that the thermoplastic fiber is a composite fiber consisting of a low melting point component and a high melting point component. The composite fiber is composed of two or more types of thermoplastic fibers having different melting points from among the above-mentioned thermoplastic fibers, and the composite fiber includes, for example, a core-sheath whose melting point is lower than that of the sheath side or the core side. Examples include thermoplastic composite fibers and/or laminated thermoplastic composite fibers with different melting points. In both core-sheath type and laminated type conjugate fibers, it is preferable that the difference in melting point between the high melting point component and the low melting point component is 30°C or more.

After forming a fiber web having a predetermined shape by mixing a predetermined amount of non-composite fibers with the composite fibers as needed, the constituent fibers are heated and melted by heating and melting the low melting point component of the composite fibers. It is formed by integrating the

As a method of heating and melting the above-mentioned fibrous web, there is a method of passing the fibrous web through a pair of heated rolls, but
In consideration of imparting texture, etc., it is preferable to pass the material through a heated air chamber as described below.

Further, the content of the thermoplastic fibers constituting the composite fibers is preferably 50% by weight or more as described above, and therefore the content of the non-composite fibers used in combination is preferably less than 50%. If the composite fiber content is less than 50% by weight, there is a possibility that the strength of the nonwoven fabric as a surface material of an absorbent article described later may not be obtained.

Examples of the non-composite fibers include non-composite fibers made of polyethylene terephthalate, polybutylene terephthalate, polypropylene, nylon-6, nylon-66, and the like.

In addition, the thermoplastic fibers used in the upper and lower layers of the nonwoven fabric 10 are selected based on the process of manufacturing the nonwoven fabric, the texture and strength when used as a surface material of an absorbent article, the average distance between fibers in the fiber web of the lower layer, etc. Then, the fineness of the upper layer fiber web is 1 to 6 deniers, and the fineness of the lower layer fiber web is 3 to 1 denier.
Preferably, it has a denier of 0. Note that the conjugate fibers and non-conjugate fibers are not limited to those mentioned above, and various other fibers can be selected as necessary. however,
Non-thermoplastic fibers such as rayon, cupro, cotton, etc.
If it has problems such as shedding, reduced bulk, and strength, it is not suitable as a material for nonwoven fabrics used as surface materials for absorbent articles.

As described above, in the nonwoven fabric 10 of this example, the convex portions 11A+ and the concave portions 11A2 are formed in the central portion 11A of the upper layer fiber web 11, and the fiber aggregation density of the convex portions 11A1 is Because of its high density, it has bulkiness (cushionability), and when used as a surface material for absorbent articles, it is difficult for liquid to return, and the fiber aggregation density of the concave portion 11A2 is low, and it has substantially no open pores. In addition, since the average distance between the fibers of the lower layer fiber web 12 is larger than that of a normal nonwoven fabric, it has excellent permeability to high viscosity liquids and has excellent permeability to high viscosity liquids. It has excellent retention of viscous substances and has a good overall feel as a surface material.

Furthermore, FIGS. 3 and 4 are diagrams showing a nonwoven fabric 10 according to another embodiment of the present invention, and the nonwoven fabric IO of this embodiment has irregularities on the entire surface of the upper layer fibrous web 11, as shown in the figures. 11A,
, 11A2 are formed in the same manner as in the above embodiment.

Therefore, the nonwoven fabric 10 of this embodiment can also be expected to have the same effects as the nonwoven fabric 10 shown in FIGS. 1 and 2.

5 and 6 are diagrams showing a nonwoven fabric 10 according to still another embodiment of the present invention, and the nonwoven fabric 10 of this embodiment is similar to the nonwoven fabric shown in FIGS. Out of 10,
All of the nonwoven fabrics 1° shown in FIGS. 1 and 2 except that the lower layer fibrous web J2 is located at the center portion 11A of the upper layer fibrous web 11 and is not present at both end portions 11B and 1'lB. It is configured in the same way. Therefore, in the nonwoven fabric 10 of this embodiment, the high viscosity liquid that has permeated through the center portion 11 of the upper layer fiber web 11 is retained by the lower layer fiber web 12 that exists only below the center portion 11A. It is possible to suppress the seepage and diffusion of the highly viscous liquid to both ends IIB and IIB of the fibrous web 11, and it is also possible to save the amount of the fibrous web used for the lower layer.

Next, an example of an absorbent article of the present invention using the nonwoven fabric 10 will be described.

The absorbent article of this example includes a liquid-permeable surface material (top sheet) that comes into contact with the skin, an absorbent body covered with the top sheet, and a back sheet that covers the back side of the absorbent body. It has a basic structure and absorbs or stores and retains excreta such as urine, feces, and menstrual blood. Examples of such absorbent articles include conventionally known disposable diapers, incontinence pads, adult diapers, and There are sanitary napkins, etc.

Thus, in the present absorbent article, the top sheet is formed of each of the above-described nonwoven fabrics 10, and when the nonwoven fabric 10 shown in FIGS. 1, 2, 5, and 6 is used, ,
A central portion 11A having a convex portion 11A1 and a concave portion 11A2 in the upper layer fiber web 11 of the nonwoven fabric 10 is located in the longitudinal center of the topsheet, and the fiber aggregate density in the nonwoven fabric 10 is located at both ends in the width direction. When the nonwoven fabric 10 shown in FIGS. 2 and 3 is used, both ends 11B and IIB are located uniformly.
1A+ and concave portions 11A2 are distributed over the entire surface. Further, when the nonwoven fabric 10 is used as a surface material, it is preferable that the central portion 11A is hydrophilic and the both end portions 11B and IIB are hydrophobic. In addition, the absorber is a conventionally known one,
For example, there are those that use crushed pulp as the main material in combination with a high-molecular absorption polymer, and those that are heat-treated as a mixture of a thermoplastic resin, cellulose fiber, and a high-molecular absorption polymer. Incidentally, this absorbent article may be appropriately provided with an elastic member for forming gears, etc., depending on its use.

Since this absorbent article is equipped with the above-mentioned nonwoven fabric 10 as a top sheet, when worn, the bulky convex portion A1 softly contacts the skin, and when in contact, the unevenness of the central portion causes soft stools, menstrual blood, etc. Highly viscous body fluid does not flow through the substantially open concave part with low fiber aggregate density] 1A2 allows high viscous body fluid to permeate into the absorbent body and suppresses or prevents the high viscosity fluid from returning; , a flat surface with a uniform fiber aggregate density at both ends makes contact with the relevant part with good texture, and high viscosity substances in the high viscosity body fluid are retained in the lower layer fiber web 12, and low viscosity substances are efficiently transferred to the absorbent body. To Penetrate.

Next, an embodiment of the method of the present invention for manufacturing the nonwoven fabric 10 will be described based on FIGS. 7 to 9.

A nonwoven fabric manufacturing apparatus suitable for carrying out the nonwoven fabric manufacturing method of the present invention is configured as shown in FIG.

That is, the above-mentioned manufacturing apparatus manufactures the nonwoven fabric shown in FIGS. 3 and 4 in which unevenness is dispersed over the entire surface of the upper layer fiber web, and as shown in FIG. a first carding machine 30 that forms a first fibrous web 11'' from supplied first fibers;
receives the first fibrous web 11' conveyed by the horizontal conveyor 40 on the downstream side of the fibrous web 11';
It is provided with an unevenness forming part 50 that forms unevenness on the surface.

The unevenness forming section 50 is provided with a pair of ventilation conveyors 51 and 52 on the upper and lower sides, which sandwich and transport the first fiber web 11. The ventilated conveyor 751 disposed on the lower side is a mesh-like endless conveyor shown in FIGS. It is preferable to do so. If the height difference h' is less than 3 rwl, it will be difficult to form irregularities or perforations in combination with the irregularities on the fiber web 11, as will be described later.On the other hand, if it exceeds 10 rwl, the belt-like web 11' after the unevenness has been formed will be air-permeable. It becomes difficult to peel off from the conveyor 51, which is not preferable. Furthermore, the number of convex portions is 10 to 3.
It is preferable that the number of protrusions is set to 5/in2. If the number of protrusions is less than 10/in2, the structural fibers are likely to be scattered by the jet air flow, and if it exceeds 35 halo 2, it will be difficult to form unevenness, which is not preferable. .

On the other hand, the ventilation conveyor 52 disposed on the upper side has 3 to 15
The first fibrous web 11'' is pressed against the lower air-permeable conveyor 51, and the fibrous web 1 is
It is an endless conveyor that is formed substantially flat so that it can hold 1°, and is rotatably supported by four rolls.

Further, the unevenness forming portion 50 is formed on a pair of breathable conveyors 5.
Air injection device 5 injects air from above onto the first fibrous web 11 held between 1.52 and causes the fibrous web 11'' to enter and follow the surface recess of the lower air-permeable conveyor 51.
It has 3. The air injection device 53 includes an injection duct 53A inserted from the side into the rotating interior of the upper ventilation conveyor 52, and a collection duct 53A inserted from the side into the rotational interior of the lower ventilation conveyor 51. A blower 53C injects air from the injection duct 53A onto the entire surface of the first fibrous web 11'' passed through the breathable conveyor 52 and pressed by the breathable conveyor 52.
While the fiber web 11' is conveyed under the spray duct 53A, the uneven surface of the air permeable conveyor 51 forms an uneven surface. Further, the airflow that has passed through the first fiber web 11° and the lower ventilation conveyor 51 is configured to flow back to the blower 53C via the collection duct 53B. Therefore, the air jet speed by the floor 53C is 20 to 20 per 1 of the first fiber web.
It is preferable to set it to 0 m/sec. 20m/s
If it is less than 20 Qm/sec, it is difficult to form a hole in combination with the unevenness or the unevenness, and conversely, if it exceeds 20 Qm/sec, the
The fiber web 11' of the fiber web 11' is disturbed, and the blower 53
C tends to have an excessive energy load and become uneconomical. Furthermore, in order to minimize the energy loss of the jet air stream, it is preferable to inject from the side of the substantially flat mesh-like ventilation conveyor 52 and from a rotational internal position as close to the ventilation conveyor 52 as possible. .

Further, the shape of the injection port can be formed by providing a large number of orifice-like pores, but a slint-like shape is preferable because it can reduce energy loss. On the other hand, the breathable conveyor 41.
The conveyance speed by 42 is set in relation to the air injection speed, and is preferably set to 10 to 100 m/min.

In addition, the first fiber web 11'', which is formed with irregularities or perforations combined with irregularities, is conveyed to the downstream side via a descending inclined conveyor 60 and a horizontal conveyor 70, 70 connected thereto, which will be described later. The semi-finished product 10' is made up of two layers, an upper and a lower layer.

Further, as shown in FIG. 7, the manufacturing apparatus described above is capable of producing a first card l! 30 and above the horizontal conveyor 70;
A second carding machine 90 forms a second fibrous web 12'' from the second fibers supplied by the second carding machine 90, and the second fibrous web 12'' formed by the second carding machine 90 is lowered and horizontally Inclined conveyors 100 for merging and polymerizing the fiber web 11'' conveyed by the conveyor 70 are sequentially provided on the downstream side, and the nonwoven fabric 1 consists of two upper and lower layers.
The semi-finished products 10'' are passed through a heat treatment section 120 by an ascending inclined conveyor 110.

The semi-finished product 10' is heat-treated in a heat treatment section +20 to form a first fibrous web 11' and a second fibrous web 12' having an unevenness or perforation formed on the entire surface.
are heat-sealed in a polymerized state and integrated as shown in FIGS. 3 and 4.

Note that as the heat treatment section 120, a heated air chamber, a pair of heated rolls, or the like is used.

Four cutters 130 are arranged in parallel at a predetermined interval on the downstream side of the heat treatment section 120, and are used to cut the semi-finished product 10 in the flow direction at both edges and the center, and wind it up as a three-wood nonwoven fabric 10 using a winder 140. is being done. In addition, it is preferable that the predetermined spacing be a spacing that is suitable for an absorbent article that uses the nonwoven fabric 10 as a surface material.

Next, one embodiment of the method for manufacturing a nonwoven fabric of the present invention will be described.

First, when fibers containing thermoplastic fibers are supplied from the first fiber supply section 20 to the first card machine 30, the first fiber web 11' is formed in the first cart machine 30, and then the unevenness forming section 50 upper and lower-pair ventilated conveyors 51.5
2, while the first fiber web 11' is conveyed and passes through the unevenness forming part 50, air is injected over the entire width via the blower 53C1 and the injection duct 53A to form the uneven part 11A and the concave part 11A2 or the unevenness forming part 50. The shaped portions 11A+, 11Az and the concave portion 11A2 are perforated to form a first fiber web 11′ which is dispersed over the entire surface and is conveyed by the horizontal conveyor 70.70. On the other hand, the fibers containing thermoplastic fibers are
The second fiber web 12' is supplied from the fiber supply unit 80 to the second card machine 90.
is formed and conveyed by the inclined conveyor 100. After that, the first fibrous web 11'' and the second fibrous web 12
“The entire surfaces of each are overlapped near the downstream end of the horizontal conveyor 70 and transferred to the heat treatment section 1 by the inclined conveyor 110.
The semi-finished product 10 is then transported to the semi-finished product 10 and fused and integrated.
” is formed. Then, while being transported, the slick-1
The uneven portions 11A, 11 are cut by 30 and dispersed.
A nonwoven fabric 10 having B is formed and wound up into three rolls by a winding section 140.

Therefore, according to this embodiment, the nonwoven fabric 10 having the uneven portions 11A1.11Az in the upper layer fiber web 11 and the fiber web 12 having a large average interfiber distance in the lower layer can be manufactured easily and at high speed. .

Furthermore, when manufacturing the nonwoven fabric 10 shown in FIGS. 1 and 2, this problem can be dealt with by changing the shape of the injection port of the injection duct 53A of the unevenness forming section 50. That is, the first fibrous web 11'.

The nonwoven fabric 10 shown in FIGS. 1 and 2 can be manufactured by using a plurality of injection ports spaced at predetermined intervals in the radial direction of the nonwoven fabric 10 and by making the area where air is not ejected a flat surface.

Moreover, the nonwoven fabric 10 shown in FIGS. 5 and 6 can also be manufactured by using an apparatus similar to each of the above-mentioned manufacturing apparatuses.

Hereinafter, the nonwoven fabric of the present invention will be further specifically explained based on the following examples.

Example 1 In this example, invention product 1 was manufactured as follows using the nonwoven fabric manufacturing apparatus shown in FIGS. 7 to 9.

The first fiber with a basis weight of 20 g/n (20 g/n) is made of a core-sheath type thermoplastic composite fiber of polyethylene telecrate/polyethylene (3 denier x 51 denier) whose surface has been made hydrophilic with 0.3% by weight of a hydrophilic surfactant. A web 11'' is formed by a first carding machine 30, and then the fibrous web 11'' is sandwiched between a concavo-convex support net 51 and a plain weave net 52, both of which have air permeability, to allow air to flow through the fibrous web 11''. The fibrous web 11 is forced into the concave portions of the uneven support net 51 by spraying the fiber web 11 to form coarse and dense portions of the fibers at a predetermined pitch, and then heated air (1
40°C) to preliminarily melt the polyethylene to improve its shape retention and conveyance properties, and then convey it on a conveyor 60.70. On the other hand, polyethylene telecrate/polyethylene core-sheath type thermoplastic composite fiber (8 denier x 51
n++n) with a basis weight of 15 g/rrf is formed into a second fiber web 12° using a second cart machine 90,
Next, the second fibrous web 12' is conveyed to the downstream side by the conveyor 100 and laminated on the first fibrous web 11' formed in the first cart machine 30 and the unevenness forming section 50, and then transferred to the heat treatment section. At 120, the thermoplastic fibers of each fiber web 11'' and 12'' are fused by heat treatment with heated air at 140°C, and the upper layer has a dispersed convex portion 11A and a concave portion 11A2, and a concave portion. 11
A nonwoven fabric 10 was produced in which A2 had substantially open holes and the lower layer had a substantially uniform fiber density.

In the nonwoven fabric 10, the average pitch of the unevenness of the upper layer fiber web 11 is 5.5 cm, and the average pore diameter of the pores is φ2.
．． 5, the convex portion 11A has a fiber aggregate density of 2.9
10-5 g/+++m'', fiber aggregate density of concave portion 11A2 is 7.OX 10-'g/lung 2, lower layer fiber web 1
The average interfiber distance of No. 2 was 250 μm.

Comparative Example 1 In this comparative example, a nonwoven fabric was produced in the same manner as in Example 1 above, except that 3 denier fibers were used in the lower layer.
This was designated as comparison hole 1.

Comparative Example 2 In this comparative example, a concavo-convex nonwoven fabric consisting only of the upper layer was produced in the same manner as in Example 1 above, except that the fiber web of the lower layer was omitted, and this was used as comparative hole 2.

Comparative Example 3 In this Comparative Example, a nonwoven fabric consisting only of the lower layer was produced in the same manner as in Example 1 above, except that the upper layer fiber web was omitted, and this was used as Comparative Hole 3.

The nonwoven fabrics of Inventive Product 1 and Comparative Holes 1 to 3 were tested for the evaluation items listed in Table 1 above, and the results are also listed in column 5 of the same table.

Table (note) Evaluation criteria *1: Lay the prepared nonwoven fabric on an absorbent material used in commercially available disposable diapers, place it on a 45° swash plate with the nonwoven fabric facing up, and place it on a swash plate from above. 3 g of artificial soft stool (moisture content 97%) was dropped onto the above non-woven fabric, and the distance that the artificial loose stool flowed down the surface of the non-woven fabric was measured, and the soft stool permeability was defined as the soft stool permeability. is cm.

*2 to *4; ○: Level with no practical problems △: Level with some practical concerns ×: Level with practical problems According to the results shown in Table 1 above, the product 1 of the present invention has a comparative hole level. Compared to 1 to 3, not only the permeability of artificial soft stool, which is a highly viscous liquid, but also the return property of the liquid is extremely low, and it also satisfies the properties required for the surface material of absorbent articles. I understand that.

Although the nonwoven fabric of the present invention has been specifically explained based on the above examples, the nonwoven fabric of the present invention is not limited to the above examples, and various changes may be made without departing from the gist of the present invention. be able to.

For example, the opening of the recessed part does not have to be a clear hole,
It is sufficient that the hole is substantially open. In addition, the above-mentioned openings do not necessarily have to be provided, and the concave portions only need to be formed to be concave to the extent that body fluids can pass therethrough and have a low fiber aggregate density, and furthermore, the uneven shape of the nonwoven fabric may be arranged regularly. You don't have to.

Further, the method for manufacturing a nonwoven fabric of the present invention is not limited to the above embodiment in which unevenness is formed while the first fibrous web is conveyed while being sandwiched between a pair of breathable conveyors 41 and 42 having unevenness. Instead, the first fibrous web may be placed on an air permeable conveyor having unevenness, and the unevenness may be formed on the fibrous web while the first fibrous web is conveyed with the fibrous web placed thereon.

〔Effect of the invention〕

The nonwoven fabric of the present invention can reliably transmit a high viscosity liquid through the concave portions of the upper layer fiber web, suppress backflow of the liquid at the convex portions, and can prevent high viscosity liquid from flowing through the lower layer fiber web. , and can reliably transmit low-viscosity substances, and has excellent properties as a surface material such as texture and texture.

In addition, since the absorbent article of the present invention uses the above-mentioned nonwoven fabric, it has excellent permeability to high viscosity body fluids such as soft stool and menstrual blood, and can suppress the return of high viscosity body fluids from coughing. It can hold objects and absorb low-viscosity materials into the absorber, and is an excellent countermeasure against clogging in the mount of the absorber.

Moreover, according to the method for producing a nonwoven fabric of the present invention, the above-mentioned nonwoven fabric suitable as a surface material of an absorbent article can be easily produced at a high speed.

[Brief Description of the Drawings] Fig. 1 is a partial perspective view conceptually showing an embodiment of the nonwoven fabric of the present invention, Fig. 2 is a sectional view taken along the line A diagram corresponding to FIG. 1 showing another embodiment of the nonwoven fabric, FIG. 4 a sectional view taken along IV-IV in FIG. 2, and FIG. FIG. 6 is a cross-sectional view of V[-Vl in FIG. 5, FIG. 7 is a perspective view showing a nonwoven fabric manufacturing apparatus that can be suitably used when implementing the nonwoven fabric manufacturing method of the present invention, and FIG. FIG. 7 is a plan view showing a part of the lower air permeable conveyor used in the unevenness forming section of the manufacturing apparatus, and FIG. 9 is a side view of the air permeable conveyor shown in FIG. 8. 10; Non-woven fabric 11; Upper layer fiber wafer 11A; Central portion 11A,; Convex portion 11Az; Concave portion 12; Upper layer fiber wafer 11', 11''i First fiber wafer 12''; Second fiber web patent

Claims (5)

[Claims] (1) A nonwoven fabric in which an upper layer fibrous web containing thermoplastic fibers and a lower layer fibrous web containing thermoplastic fibers are integrated, and the upper layer fibrous web is dispersed throughout at least in the central portion. A convex portion and a concave portion are formed, and the fiber aggregation density of the concave portion is lower than that of the convex portion, and the fiber web of the lower layer has a substantially uniform fiber aggregation density, and at least A nonwoven fabric characterized by being present at the position of the part. (2) The nonwoven fabric according to claim (1), wherein the concave portion in the fiber web portion of the upper layer is substantially open. (3) The average interfiber distance of the lower layer fiber web is 80 to 30
The nonwoven fabric according to claim 1, which has a particle diameter of 0 μm. (4) An absorbent article that includes a surface material that comes into contact with the skin and an absorbent body covered with the surface material, and that absorbs bodily fluids and other excreta, wherein the surface material is used as claimed in claim (1) or (2). An absorbent article formed from the nonwoven fabric described above. (5) Forming a first fibrous web containing thermoplastic fibers and a second fibrous web containing thermoplastic fibers, placing the first fibrous web on an air permeable conveyor having unevenness, and While the web is conveyed with the web placed on it, gas is injected onto the surface of the fibrous web to make it follow the recesses of the breathable conveyor to form uneven parts on the fibrous web, and then the first A second fibrous web is positioned below at least the uneven portion of the fibrous web and the second fibrous web is overlapped, and then both are heated to fuse the respective thermoplastic fibers to integrate the two. The method for producing a nonwoven fabric according to claim (1).