JP7555965B2 - Nonwoven fabric and absorbent article - Google Patents

Description

The present invention relates to nonwoven fabrics and absorbent articles.

Sanitary napkins and disposable diapers have traditionally been used as absorbent articles. In absorbent articles, a liquid-permeable sheet (top sheet, second sheet, etc.) is provided on the side that comes into contact with the wearer's skin (closer to the skin than the absorbent body). Liquid-permeable sheets are required to have high liquid permeability, and nonwoven fabrics are considered to be suitable.

For example, Patent Document 1 discloses such a nonwoven fabric that contains spiral (coil) crimped fibers. The crimped fibers include latent crimped fibers that develop a spiral shape when heated, and manifested crimped fibers that have a spiral shape from the beginning.

JP 2002-285464 A

However, when using latent crimped fibers, the fibers are crimped by heat treatment, making it difficult to control the degree of shrinkage and maintaining a large spiral crimped shape. This makes it difficult to intentionally form low-density areas that allow the penetration of high-viscosity liquids (loose stool, etc.).

The present invention has been made in consideration of the above-mentioned problems, and aims to make it easier for high-viscosity liquids to pass through.

The main invention for achieving the above-mentioned object is a nonwoven fabric for use in absorbent articles, which contains a plurality of manifest crimp fibers, is formed from one or more of the manifest crimp fibers, has a plurality of arc portions visible from the surface, and is characterized in that, when the average fiber length of the manifest crimp fibers is L and the average circumference of a circle passing through three points on the arc portions is S, the nonwoven fabric satisfies S≦2×L.

Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

The present invention makes it easier for high viscosity liquids to pass through.

1 is a schematic perspective view of a nonwoven fabric 10 according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of the shape (spiral shape) of the apparent crimped fiber 11. FIG. 1 is a diagram showing the evaluation results of the relationship between fiber length and crimp number. FIG. 13 is a diagram showing evaluation results of crimp radius. FIG. 13 is a diagram showing the observation results of the surface of a sheet. FIG. 13 is a diagram showing the observation result of a cross section of a sheet. FIG. 2 is a comparison diagram of the sheet surfaces of Example 1, Example 2, and a comparative example. FIG. 8 is an enlarged view of Example 1 (No. 1) of FIG. 7 . FIG. 1 is a diagram showing the results of evaluation of the state of sheets formed according to differences in fiber length. FIG. 2 is a schematic perspective view of the diaper 1 as seen from the abdominal side. FIG. 2 is a plan view of the diaper 1 in an unfolded and extended state. This is a schematic cross-sectional view taken along line AA in FIG. 1 is a schematic perspective view showing a top sheet 51, a second sheet 52, and an absorbent body 53 of an absorbent main body 50 separated from each other.

The present specification and accompanying drawings make clear at least the following:

A nonwoven fabric for use in absorbent articles, comprising a plurality of manifest crimped fibers, formed from one or more of the manifest crimped fibers, having a plurality of arc portions visible from the surface, and characterized in that, where L is the average fiber length of the manifest crimped fibers and S is the average circumference of a circle passing through three points on the arc portions, S satisfies S≦2×L.

With such nonwoven fabrics, an arc of at least half the circumference of a circle is formed, and the shape of the arc is easily maintained. This results in low-density areas due to the apparent crimped fibers, making it easier for high-viscosity liquids (such as loose stools) to pass through.

It is desirable for such a nonwoven fabric to further satisfy S≦L.

With this type of nonwoven fabric, the circles formed make it easier to maintain its shape.

In such a nonwoven fabric, it is desirable that the manifested crimp fibers are bonded together with an adhesive.

With this type of nonwoven fabric, the adhesive makes it easy for multiple fibers to become entangled, which makes it easier to form the edge of a circle.

In such a nonwoven fabric, it is desirable that at least a portion of the arc portion is composed of a plurality of the manifested crimp fibers bonded to each other by the adhesive.

This type of nonwoven fabric allows the edges of the circle to be formed more firmly.

In such a nonwoven fabric, it is desirable that the fineness of the manifested crimped fibers is less than 30 denier.

This type of nonwoven fabric can achieve a good texture (if the fineness is too large, the number of threads will be too small and the texture will not be achieved).

In such a nonwoven fabric, it is desirable that the content of the manifested crimp fibers is greater than 80% by weight.

Such nonwoven fabrics can improve liquid permeability and cushioning properties.

In such a nonwoven fabric, it is desirable for the fiber density to be less than 0.065 g/cm ³ .

Such nonwoven fabrics can increase liquid permeability.

In such a nonwoven fabric, it is desirable that the average radius of the circles is smaller than the thickness of the nonwoven fabric.

With such a nonwoven fabric, an arc portion of more than half a circle can be formed in the thickness direction (if the radius is greater than or equal to the thickness of the nonwoven fabric, an arc portion of more than half a circle cannot be formed in the thickness direction).

In such a nonwoven fabric, it is desirable that the area of the surface other than the circular areas is greater than the total area of the circular areas surrounded by the multiple circles.

Such nonwoven fabrics can be made moderately permeable (so they don't become too porous).

In such a nonwoven fabric, the absorbent article is provided with an absorbent body that absorbs liquid, and a sheet member that is disposed closer to the skin than the absorbent body and has a plurality of holes penetrating in the thickness direction, and is desirably disposed between the sheet member and the absorbent body.

Such nonwoven fabric allows some of the highly viscous liquid to be transferred from the sheet member to the absorbent body.

In such a nonwoven fabric, it is desirable that one of the plurality of circles at least partially overlaps a certain hole in the sheet member, and another circle does not overlap the hole in the sheet member.

With such a nonwoven fabric, the overlapping areas make it easier for high-viscosity liquids to transfer to the absorbent, while the non-overlapping areas prevent liquid from flowing back from the nonwoven fabric to the sheet member.

The present invention also provides an absorbent article comprising an absorbent body that absorbs liquid and a nonwoven fabric that is disposed closer to the skin than the absorbent body, the nonwoven fabric containing a plurality of apparent crimp fibers, being formed of one or more of the apparent crimp fibers, having a plurality of arc portions visible from the surface, and wherein, when the average fiber length of the apparent crimp fibers is L and the average circumference of a circle passing through three points on the arc portions is S, the absorbent article satisfies S≦2×L.

Such absorbent articles allow highly viscous liquids (such as loose stools) to easily penetrate into the absorbent body.

====Embodiment===
<<About nonwoven fabrics>>
FIG. 1 is a schematic perspective view of a nonwoven fabric 10 according to the present embodiment.

The nonwoven fabric 10 of this embodiment is a nonwoven fabric used in absorbent articles such as diapers and sanitary napkins, and is particularly suitable for the second sheet of an absorbent article (a sheet placed between the top sheet and the absorbent body).

Such absorbent articles are required to have good liquid permeability. In particular, in the case of diapers, there is a need to allow highly viscous liquids (such as loose stools) to pass through. Therefore, the nonwoven fabric 10 of this embodiment contains multiple crimped fibers as its constituent fibers, and as described below, has high liquid permeability and cushioning properties.

A crimped fiber is a fiber having a crimped shape (zigzag, Ω, spiral, etc.), and in this embodiment, a helical crimped fiber is used. As helical crimped fibers, latent helical crimped fibers (hereinafter also referred to as latent crimped fibers) and manifest helical crimped fibers (hereinafter also referred to as manifest crimped fibers) are known. A latent crimped fiber is a fiber that shrinks when heated to develop a helical shape, and it is difficult to control the development of the helical shape. For this reason, when a nonwoven fabric is formed from latent crimped fibers, it tends to have a uniform density structure (it is difficult to create low density parts), and there is a risk that it may not be possible to permeate a high viscosity liquid.

Therefore, in the nonwoven fabric 10 of this embodiment, manifest crimp fibers 11 that have a helical shape from the beginning are used as the crimped fibers. That is, the nonwoven fabric 10 of this embodiment contains multiple manifest crimp fibers 11. In this embodiment, fibers composed of a single component (e.g., polyester) are used as the manifest crimp fibers 11. In addition, the nonwoven fabric 10 is formed of one or more manifest crimp fibers 11 and has multiple arc portions (arc portions 12 shown in FIG. 2) that are visible from the surface.

Figure 2 is an explanatory diagram of the shape (helical shape) of the manifested crimp fiber 11. Here, one fiber (manifested crimp fiber 11) is shown. In the figure, the fiber length of the manifested crimp fiber 11 is L, and the circumference of a circle 13 passing through the three points of the arc portion 12 is S.

As shown in the figure, when S>2×L, the arc portion 12 is an arc that is less than half the circumference of the circle 13, and it is difficult to maintain the shape of the arc. In addition, it is difficult to form a low-density portion that allows high-viscosity liquids (loose stool, etc.) to pass through.

Therefore, in this embodiment, S≦2×L is satisfied. In this case, the manifested crimped fibers 11 form an arc portion 12 that is more than half the circumference of the circle 13, making it easier to maintain the shape of the arc portion 12. This makes it easier for low-density portions to be formed in the nonwoven fabric 10 due to the manifested crimped fibers 11, making it easier for high-viscosity liquids (loose stool, etc.) to pass through.

Furthermore, when S≦L is satisfied, the arc portion 12 at least becomes circular and the circle 13 is formed. This makes it easier to maintain the spiral shape. However, in the case of the manifested crimp fiber 11 formed by the airlaid method described below, if S is too small, the circle 13 becomes small and the liquid permeability deteriorates, so it is preferable that S>L/4 or S>L/5. Also, in the case of the manifested crimp fiber 11 formed by the carding machine described below, it is preferable that S>L/17.

In Figure 2, the arc portion 12 (circle 13) is formed from a single manifested crimp fiber 11, but in the nonwoven fabric 10, the arc portion 12 (circle 13) may be formed from multiple manifested crimp fibers 11.

One method for manufacturing the nonwoven fabric 10 is to form a web by laminating short fibers containing the manifested crimped fibers 11 using airlaid, and then bonding the fibers together using a liquid binder (corresponding to an adhesive), followed by drying to form a sheet. Note that this is not limited to airlaid, and the web may also be formed using, for example, a carding machine. In this case, the texture is better than with airlaid, and longer fibers can be used. However, compared to carding, airlaid is more likely to maintain the spiral crimp shape during the process. Therefore, it is more preferable to form the web using airlaid.

In this embodiment, as described above, the fibers are bonded with a liquid binder. In other words, the manifested crimp fibers 11 are bonded together with the liquid binder. This makes it easier for multiple manifested crimp fibers 11 to become entangled, making it easier to form the edge of the circle 13.

As liquid binders, emulsion binders such as acrylic ester copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol (PVA), and styrene-butadiene (SBR) can be used.

Furthermore, by applying to the fibers a preparation liquid in which an inorganic antibacterial agent in which silver ions are supported on an inorganic ion exchanger such as zirconium or zeolite, or an inorganic deodorant with an average particle size of 0.1 to 5 μm in which hydroxyl groups (-OH) or amino groups (-NH2) are added to inorganic substances such as zirconium or silica, is uniformly dispersed in the above-mentioned emulsion binder, a hydrophilic nonwoven fabric having antibacterial and deodorant properties in addition to elasticity and bulk recovery properties can be obtained. In addition, other functional agents (such as soft stool modifiers) may be applied without being limited to this.

It is also preferable that at least a portion of the arc portion 12 is made up of a plurality of manifested crimp fibers 11 bonded together with a liquid binder (adhesive). This allows the edge of the circle 13 to be more firmly formed.

The average fiber length of the apparent crimped fibers 11 is preferably 5 to 15 mm (see Example 1 described later). The fiber length here is the fiber length in the stretched state. If the fiber length is shorter than 5 mm, the circle 13 in the crimped state becomes smaller, and the liquid permeability decreases. If the fiber length is longer than 15 mm, the fibers tend to become entangled with each other, making air laying difficult (the formation cannot be achieved). By setting the average fiber length to 5 to 15 mm, a circular arc portion 12 (circle 13) of a moderate size can be formed, and a good formation can be achieved. However, when the web is manufactured using a carding machine, the formation is good, so the fiber length may be longer than the above. Specifically, when using a carding machine, the average fiber length is preferably 25 to 76 mm, and more preferably 35 to 51 mm. In this case, it is sufficient to satisfy S≦2×L. In this case, S＞L/25 may be about the same.

In addition, if the fineness of the manifested crimped fibers 11 is too large, the number of fibers will be small and the texture will not be achieved (it will be uneven), so the fineness of the manifested crimped fibers 11 is preferably less than 30 denier (33.6 dtex). More preferably, it is 3.6 to 8.9 denier (4 to 10 dtex). This allows for a good texture to be achieved.

In addition, the content of the manifested crimped fibers 11 in the nonwoven fabric 10 is preferably greater than 80% by weight. The content here means the proportion of the manifested crimped fibers 11 in the total fibers in the nonwoven fabric 10. In this embodiment, only the manifested crimped fibers 11 are used as the fibers constituting the nonwoven fabric 10, and although the nonwoven fabric 10 also contains adhesive, when looking at the fibers alone, the proportion of the manifested crimped fibers 11 is 100% by weight. In addition, it is not limited to the manifested crimped fibers 11, and other fibers may be included, but even in that case, it is preferable that the manifested crimped fibers 11 are contained in a proportion greater than 80% by weight. This can improve liquid permeability and cushioning properties.

Furthermore, the fiber density of the nonwoven fabric 10 is preferably less than 0.065 g/cm ³ , which can increase the liquid permeability.

In addition, when the radius of the circle 13 is equal to or greater than the thickness of the nonwoven fabric 10, it is preferable that the average radius of the circle 13 is smaller than the thickness of the nonwoven fabric 10, since the arc portion 12 of more than half the circumference of the circle 13 cannot be formed in the thickness direction. This allows the arc portion 12 of more than half the circumference of the circle 13 to be formed in the thickness direction, improving cushioning properties. The thickness of the nonwoven fabric 10 can be measured using a thickness gauge (THICKNESS GAUGE UF-60, manufactured by Daiei Scientific Instruments Manufacturing Co., Ltd.) after the sheet (nonwoven fabric) is placed in a hot air dryer at 70°C for 10 minutes to fully recover its bulk. The radius of the arc formed in the thickness direction is the part (semicircle or more) that is visible in the image of an electron microscope. The values of the thickness of the nonwoven fabric 10 and the average radius of the circle 13 will be described later.

<<Example>>
The present invention will now be described in more detail with reference to examples.

<Evaluation of fiber shape>
Sample: Fiber with apparent crimp before being made into a sheet (fiber length 5mm to 20mm after opening with a jet opener, fiber length 51mm after opening with a carding machine)
Material: Polyethylene terephthalate (PET)
Fiber length: 5 mm, 10 mm, 15 mm, 20 mm, 51 mm (average value of cut products)
Evaluation items: number of crimps, crimp radius Measuring equipment: Keyence VHX-7100

For the above samples, it was judged whether the central angle of the formed arc portion was 180 degrees or more, and those that were 180 degrees or more (S≦2×L) were rated as OK (○), and those less than 180 degrees (S>2×L) were rated as NG (×) (see Figure 2). The central angle was automatically measured by selecting three points in total, including both ends of the arc, in the measurement mode (arc) of the measuring device (VHX-7100), and judged whether it was 180 degrees or more. Furthermore, the fiber shape (number of crimps, crimp radius) of the fibers that were judged to be OK (○) was evaluated.

(Number of crimps)
Figure 3 shows the evaluation results of the relationship between fiber length and crimp number. For reference, the figure also shows general fibers. The crimp number is the actual value measured by a measuring device and the value converted per inch. The crimp number shown in Figure 3 is the average number of crimped parts that were judged as OK by the above judgment for 30 random fibers.
As shown in Figure 3, the longer the fiber length, the greater the number of crimps (measured value), although the number of crimps per inch is roughly the same (about 6 crimps) regardless of fiber length.

(Crimping radius)
4 is a diagram showing the evaluation results of the crimp radius. Here, the radius of a circle 13 (a circle passing through three points of the arc portion 12) formed by the arc portion 12 judged as OK was obtained. The crimp radius was automatically measured by specifying three points on the arc in the measurement mode (radius) of a measuring device (VHX-7100).
The crimp radius shown in Figure 4 is the average value of the radii of all crimped parts judged to be OK for 30 random fibers, as in Figure 3. The crimp radius, like the number of crimps per inch, is almost the same value (about 0.9 to 1 mm) regardless of the fiber length.

<Evaluation of the condition when made into a sheet>
Example 1 was produced as follows. Among the above-mentioned apparently crimped fibers, those with a fiber length of 5 mm were formed by an airlaid method to obtain a fiber web of 35 gsm. The obtained fiber web was then impregnated with an acrylic emulsion for a binder, and after draining, passed through a dryer at 150°C to obtain a sheet in which the fibers were bonded together with an adhesive. The average basis weight of the obtained sheet was 50 g/ ^cm2 .
Example 2 was prepared as follows. Among the above-mentioned apparently crimped fibers, those with a fiber length of 51 mm were formed by a carding method to obtain a fiber web of 35 gsm. The obtained fiber web was then impregnated with an acrylic emulsion for a binder, and after draining, passed through a dryer at 150°C to obtain a sheet in which the fibers were bonded together with an adhesive. The average basis weight of the obtained sheet was 50 g/ ^cm2 .
As a comparative example, a sheet (nonwoven fabric) using general fibers (fibers that are not spirally crimped) that are only mechanically crimped was also observed. The comparative example was created as follows. PE/PET (S/C) fibers with a fiber length of 5 mm and a thickness of 8.7 T were formed using an airlaid method and passed through a dryer at 145°C to obtain a sheet in which the PE on the sheath side of the fibers were heat-fused together. The average basis weight of the obtained sheet was 50 g/ ^cm2 .

Figure 5 shows the results of observation of the surface of the sheet. Figure 6 shows the results of observation of the cross section of the sheet. Note that in Figures 5 and 6, observation was performed using an electron microscope (FLEX SEM1000 manufactured by Hitachi Technologies) at a magnification of 30 times. Also, Figure 7 is a comparison diagram of the sheet surfaces of Example 1, Example 2, and Comparative Example. Figure 7 shows the results of observation of three sheets (No. 1, No. 2, No. 3) for each of Example 1, Example 2, and Comparative Example. Also, Figure 8 is an enlarged view of Example 1 (No. 1) in Figure 7. Figure 8 illustrates a circle 13 formed by the manifested crimp fibers. Note that in Figures 7 and 8, observation was performed using a digital microscope (VHX-7100 manufactured by Keyence Corporation).

As shown in FIG. 8, multiple circles 13 are formed on the surface of Example 1 by one or more manifested crimped fibers. The circular region R surrounded by these circles 13 is a low-density area with a low fiber density. In contrast, in the comparative example, no circles are formed as in Example 1, and the fibers are arranged almost evenly (see FIG. 5 and FIG. 7). Thus, in Example 1, more low-density areas (circular regions R) are formed than in the comparative example, and it is easier for high-viscosity liquids to pass through than in the comparative example. In addition, as shown in FIG. 6, in Examples 1 and 2, arcs are formed in the thickness direction as well, making the thickness greater than in the comparative example, and improving cushioning properties.

The radius of the circle 13 shown in FIG. 8 was automatically measured by specifying three points on the arc in the measurement mode (radius) of the measuring device (VHX-7100). In this case, when multiple spirally crimped fibers are entangled like a bundle to form a single arc, the radius was measured by specifying three points in the center of the bundle. As a result, the average radius of the multiple circles 13 shown in FIG. 8 was 0.73 mm, and the average circumference of the circles 13 was 4.58 mm. Since the fiber length of the apparent crimped fiber is 5 mm, S≦2×L is satisfied. Here, the average circumference is calculated by extracting 10 or more circles 13 in an area where 10 or more arcs due to apparent crimped fibers are visible (a rectangular area with a long side of about 16 mm and a short side of about 12 mm in FIG. 8), and averaging the circumference of each of the circles 13. The above average circumference is equal to the circumference of a circle formed by the average radius of the extracted circles 13 (the average circumference can be calculated from the average radius).

Similarly, multiple circles 13 (circular regions R) are formed for No. 2 and No. 3 of Example 1 (not shown), and the average radius of the circle 13 in No. 2 is 0.82 mm, and the average radius of the circle 13 in No. 3 is 0.83 mm. The average circumference of the circle 13 in No. 2 is 5.02 mm, and the average circumference of the circle 13 in No. 3 is 5.21 mm, so both satisfy S≦2×L. Similarly, multiple circles are formed for No. 1, No. 2, and No. 3 of Example 2 (not shown), and the average radii of the circles in No. 1, No. 2, and No. 3 are 0.87 mm, 0.89 mm, and 0.95 mm, respectively. And the average circumferences of the circles in No. 1, No. 2, and No. 3 of Example 2 are 5.54 mm, 5.57 mm, and 5.94 mm, respectively, so each satisfies S≦2×L.

In addition, when the thickness of the nonwoven fabric 10 was measured with a thickness gauge using the above-mentioned method, it was 1.65 mm in Example 1 (fiber length 5 mm), 2.76 mm in Example 2 (fiber length 51 mm), and 0.76 mm in the comparative example (non-helical stretch fiber). In Examples 1 and 2, in which arc portions are formed by the apparently crimped fibers, the average radius of each of the multiple circles described above is smaller than the thickness of the nonwoven fabric.

In addition, in the sheet surface shown in Figure 8, it is preferable that the area outside the circular region R is larger than the total area of the circular region R surrounded by the multiple circles 13. This allows for appropriate liquid permeability (in the opposite case, the sheet may become too porous and allow too much liquid to pass through).

Figure 9 shows the results of evaluating the state of sheets when different fiber lengths are used. Here, three sheets (No. 1, No. 2, No. 3) were made using apparent crimp fibers with fiber lengths of 5 mm, 10 mm, 15 mm, and 20 mm formed by the airlaid method, and the sheet surfaces were observed.

In Figure 9, even if the fiber length is longer than 5 mm, the spiral shape is maintained when the fiber is made into a sheet (i.e., multiple circles are formed by the manifested crimped fibers), and liquid permeability can be improved. However, as the fiber length becomes longer, the fibers tend to become entangled and the texture cannot be achieved. For this reason, in the case of spirally crimped fibers formed by the airlaid method, the fiber length is preferably 5 to 15 mm.

On the other hand, when making a web by opening fibers with a carding machine, the fibers are caught on the wire of the carding machine and loosened to form a uniform fiber web, so a relatively long fiber length makes it easier for them to be caught on the wire. Then, by repeatedly passing the web over the wire, the fiber direction is adjusted and the fibers become uniformly textured. Therefore, in the case of spirally crimped fibers formed by a carding machine, a fiber length of 25 to 64 mm is preferable.

<<About absorbent articles>>
In the following, the nonwoven fabric 10 of the present embodiment will be described as being applied to a pants-type disposable diaper 1 (hereinafter, simply referred to as "diaper 1"). However, the present invention is not limited to this, and can also be applied to other absorbent articles such as other types of diapers, sanitary napkins, panty liners, and urine pads.

Figure 10 is a schematic perspective view of the diaper 1 as viewed from the ventral side. Figure 11 is a plan view of the diaper 1 in an unfolded and stretched state. Figure 12 is a schematic cross-sectional view taken along the line A-A in Figure 11. Note that the "stretched state" in Figure 11 refers to a state in which the product (diaper 1) is stretched without wrinkles, specifically, a state in which each of the components constituting the diaper 1 (e.g., the front body portion 30, described below, etc.) has been stretched to a length that matches or is close to the dimensions of the individual components. Figure 13 is a schematic perspective view showing the top sheet 51, second sheet 52, and absorbent body 53 of the absorbent main body 50 separated from each other.

In the pants-type state of Fig. 10, the diaper 1 has three mutually orthogonal directions: the up-down direction, the left-right direction (also called the width direction), and the front-to-rear direction. In the following, in the up-down direction, the side facing the wearer's torso is referred to as the "upper side", and the side facing the wearer's crotch is referred to as the "lower side". In the front-to-rear direction, the side facing the wearer's stomach is referred to as the "front side", and the side facing the wearer's back is referred to as the "rear side". In the left-to-right direction, the right side when the diaper 1 is viewed from the front is referred to as the "right side", and the left side is referred to as the "left side".

11 and 12, the diaper 1 has three mutually orthogonal directions: a longitudinal direction, a left-right direction, and a thickness direction. The left-right direction (width direction) in the unfolded state is the same as the left-right direction in the pants-type state (FIG. 10). The longitudinal direction in the unfolded state is along the up-down direction in the pants-type state. As shown in FIG. 12, in the "thickness direction" perpendicular to the up-down direction (longitudinal direction) and the left-right direction, the side that comes into contact with the skin of the wearer is referred to as the "skin side," and the opposite side is referred to as the "non-skin side."

The diaper 1 of this embodiment has a crotch exterior part 20, a front body part 30, a rear body part 40, and an absorbent body 50. The crotch exterior part 20, the front body part 30, and the rear body part 40 correspond to exterior members and are joined to the absorbent body 50. These exterior members form the ventral waist part 1A, the crotch part 1B, and the rear waist part 1C, as shown in FIG. 11. In the diaper 1 of this embodiment, the exterior member is composed of three members (the crotch exterior part 20, the front body part 30, and the rear body part 40), but this is not limited to this. For example, the crotch exterior part 20, the front body part 30, and the rear body part 40 may be a single member. Also, the crotch exterior part 20 may not be included.

The crotch outer part 20 is a part that is located under the crotch of the wearer when the diaper 1 is worn (a part that constitutes part of the crotch part 1B). The crotch outer part 20 is formed from a spunbond nonwoven fabric or the like.

The front body portion 30 is a portion located on the wearer's ventral waist when the diaper 1 is worn (mainly a portion constituting the ventral waist portion 1A). The front body portion 30 has a ventral inner layer sheet 31 and a ventral outer layer sheet 33 stacked in the thickness direction. As shown in FIG. 12, the ventral inner layer sheet 31 is disposed on the skin side in the thickness direction, and the ventral outer layer sheet 33 is disposed on the non-skin side in the thickness direction. The upper end of the ventral outer layer sheet 33 protrudes upward from the upper end of the ventral inner layer sheet 31, and the protruding portion is folded back downward on the skin side in the thickness direction at the position of the upper end 30eu of the front body portion 30 to form a folded back portion 33f. By covering the upper end 30eu of the front body portion 30 with the folded back portion 33f, the upper end edge of the front body portion 30 (i.e., the waist opening BH) is less likely to dig into the wearer's skin when the diaper 1 is worn, and discomfort in the ventral waist portion 1A is less likely to occur.

In addition, an elastic member such as rubber thread is provided between the ventral inner layer sheet 31 and the ventral outer layer sheet 33 in the thickness direction. In this embodiment, as shown in Figures 11 and 12, a plurality of ventral waist elastic members 34 are provided in the region between the right end and the left end in the left-right direction of the front body portion 30. The plurality of ventral waist elastic members 34 are sandwiched and joined between the ventral inner layer sheet 31 and the ventral outer layer sheet 33 at intervals in the vertical direction and in a state stretched in the horizontal direction at a predetermined stretch ratio. The ventral waist elastic members 34 thus provided impart widthwise stretchability to the front body portion 30 of the diaper 1.

In addition, multiple waist elastic members 35 are similarly spaced apart in the vertical direction in the area along the edge of the waist opening BH of the front body portion 30.

The rear body section 40 is a portion located on the back waist of the wearer when the diaper 1 is worn (mainly a portion constituting the back waist section 1C). The structure of the rear body section 40 is substantially the same as that of the front body section 30. That is, the rear body section 40 has a back inner layer sheet 41 and a back outer layer sheet 43 stacked in the thickness direction. The upper end of the back outer layer sheet 43 protrudes upward from the upper end of the back inner layer sheet 41, and the protruding portion is folded back downward toward the skin side in the thickness direction at the position of the upper end 40eu of the rear body section 40 to form a folded back portion 43f. This makes it difficult for the upper end edge (waist opening BH) of the rear body section 40 to dig into the wearer's skin when the diaper 1 is worn, making it difficult for discomfort to occur in the back waist section 1C.

11 and 12, a plurality of rear waist elastic members 44 are provided in the region between the right end and the left end of the rear body portion 40 in the left-right direction. The rear waist elastic members 44 are sandwiched and joined between the rear inner layer sheet 41 and the rear outer layer sheet 43 at intervals in the vertical direction and in a state stretched in the left-right direction at a predetermined stretch ratio. The rear waist elastic members 44 impart widthwise elasticity to the rear body portion 40 of the diaper 1. A plurality of waist elastic members 45 are also provided at intervals in the vertical direction in the region along the edge of the waist opening BH of the rear body portion 40. The intervals between the rear waist elastic members 44 and the waist elastic members 45 adjacent in the vertical direction are the same as the intervals between the ventral waist elastic members 34 and the waist elastic members 35, respectively.

11, a plurality of leg elastic members 36, 46 such as rubber thread are provided in the areas along the edges of the pair of leg openings HL of the front body section 30 and the back body section 40. The leg elastic members 36, 46 are attached in a stretched state between the ventral inner layer sheet 31 and the ventral outer layer sheet 33, and between the dorsal inner layer sheet 41 and the dorsal outer layer sheet 43. Therefore, the front body section 30 and the back body section 40 fit around the legs of the wearer.

The absorbent body 50 has a function of absorbing urine and other excrement, and is generally rectangular in plan view as shown in Fig. 11, with its longitudinal direction aligned with the vertical direction of the diaper 1 and positioned in the left-right center. Details of the absorbent body 50 will be described later.

11, the absorbent body 50 is folded in half at a predetermined position CL in the longitudinal direction (vertical direction) of the absorbent body 50, and the front body section 30 and the rear body section 40, which face each other in this folded state, are joined by welding or the like at the ventral side joining section 30es and the rear side joining section 40es. As a result, the front body section 30 and the rear body section 40 are connected in a ring shape to form a pants-type diaper 1 having a waist opening BH and a pair of leg openings LH, LH as shown in FIG.

<Regarding the absorbent body 50>
As described above, the absorbent body 50 has a function of absorbing excrement (liquid) such as urine. In the diaper 1 of this embodiment, the absorbent body 50 has, in order from the skin side (the side contacting the wearer) in the thickness direction, a top sheet 51, at least a part of which is liquid permeable, a liquid permeable second sheet 52 (nonwoven fabric 10), an absorbent body 53, and a liquid impermeable back sheet 54, as shown in Fig. 12.

The top sheet 51 (corresponding to the sheet member) is, for example, a nonwoven fabric, and has a plurality of holes 51a penetrating in the thickness direction. When the top sheet 51 is a nonwoven fabric, a spunlace nonwoven fabric formed from cellulose fibers such as rayon, synthetic resin fibers, or an air-through nonwoven fabric formed from the synthetic resin fibers can be used. The top sheet 51 of this embodiment is formed from fibers having a smaller fineness than the apparent crimped fibers 11 of the second sheet 52. It should be noted that the top sheet 51 is not limited to a nonwoven fabric, and may be a resin film having a large number of liquid-permeable holes, a net-like sheet having a large number of meshes, or the like. Examples of materials for the resin film or net-like sheet include polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and the like.

When the top sheet 51 is made of thermoplastic resin fibers such as polypropylene or polyethylene, the holes 51a can be formed, for example, using heated pin members (not shown). Specifically, through holes can be formed in the sheet using a pair of upper and lower molds consisting of an upper mold in which multiple pin members are arranged and a lower mold in which multiple holes are arranged. That is, the pin members of the upper mold are inserted into the holes of the lower mold, thereby forming through holes (holes 51a) in the sheet (here, the top sheet 51) sandwiched between the upper and lower molds.

The diameter and arrangement of the holes 51a formed in the top sheet 51 can be adjusted by the thickness and arrangement of the pin members of the upper mold. The arrangement of the holes 51a is not particularly limited, and may be a staggered, lattice, wave, or other pattern. In this embodiment, the shape of the holes 51a is round (circular), but is not limited thereto and may be, for example, an elliptical or rectangular shape.

The back sheet 54 is a liquid-impermeable sheet, and is made of a material that can prevent liquid (excrement, etc.) absorbed in the absorbent 53 from leaking out. In addition, by using a moisture-permeable material, it is possible to reduce stuffiness when worn, and to reduce discomfort when worn.

Examples of such materials include liquid-impermeable films mainly made of polyethylene (PE) or polypropylene (PP), breathable films, and composite sheets in which a liquid-impermeable film is laminated on one side of a nonwoven fabric such as spunbond. Preferably, hydrophobic nonwoven fabrics, impermeable plastic films, and laminate sheets of nonwoven fabric and impermeable plastic films can be used. Alternatively, SMS nonwoven fabrics in which highly water-resistant meltblown nonwoven fabrics are sandwiched between strong spunbond nonwoven fabrics may be used.

The absorbent 53 is a member that has the function of absorbing and retaining excrement (liquid) inside. It is preferable that the absorbent 53 is bulky, does not easily lose its shape, and is less chemically irritating. For example, an absorbent material made of fluffed pulp or airlaid nonwoven fabric and a highly absorbent polymer can be used.

Examples of fluff-like pulp include chemical pulp, cellulose fiber, and artificial cellulose fibers such as rayon and acetate. Examples of air-laid nonwoven fabrics include those in which pulp and synthetic fibers are heat-sealed or fixed with a binder. Examples of superabsorbent polymers (SAPs) include particulate or fibrous polymers based on starch, acrylic acid, or amino acids.

The shape and structure of the absorbent body 53 can be changed as necessary, but the total absorption capacity of the absorbent body 53 must correspond to the designed insertion amount and the desired use as an absorbent article. In addition, the size and absorption capacity of the absorbent body 53 are changed according to the use.

In this embodiment, the absorbent body 53 has a two-layer structure and is composed of an upper core 53a and a lower core 53b arranged on the non-skin side of the upper core 53a in the thickness direction. However, this is not limited to this, and the absorbent body 53 may be composed of a single layer structure. The absorbent body 53 may also be covered with a liquid-permeable sheet such as tissue.

13, a second sheet 52 made of the nonwoven fabric 10 of this embodiment is provided between the top sheet 51 and the absorbent body 53 (i.e., closer to the skin than the absorbent body 53). The second sheet 52 is a sheet for improving absorbency by providing a density gradient with the top sheet 51, preventing backflow of excrement, improving cushioning, etc. The second sheet 52 (nonwoven fabric 10) of this embodiment has a low-density portion formed by the manifested crimp fibers 11, which makes it easy for a portion of a highly viscous liquid to transfer from the top sheet 51 to the absorbent body 53.

13, the top sheet 51 has a plurality of holes 51a, and the second sheet 52 has a plurality of circles 13 formed by one or more manifested crimp fibers 11. In this embodiment, the holes 51a and the circles 13 are approximately the same size. In addition, the holes 51a of the top sheet 51 are formed in a predetermined arrangement (pattern), whereas the circles 13 of the second sheet 52 are formed randomly. For this reason, there are areas where the holes 51a and the circles 13 overlap each other, and areas where they do not overlap each other. In other words, a certain circle 13 among the multiple circles 13 of the second sheet 52 at least partially overlaps a certain hole 51a of the top sheet 51, and another circle 13 does not overlap the hole 51a of the top sheet 51. In this way, the existence of areas where the circles 13 and the holes 51a overlap each other makes it easier to transfer high-viscosity liquid to the absorbent 53. In addition, the existence of areas where they do not overlap can suppress backflow from the second sheet 52 to the top sheet 51.

As described above, the nonwoven fabric 10 of this embodiment is highly permeable to high-viscosity liquids such as loose stool, and by applying it to the second sheet 52 of the diaper 1, it is possible to facilitate the transfer of some of the high-viscosity liquid from the top sheet 51 to the absorbent body 53.

===Other embodiments===
Although the embodiment of the present invention has been described above, the above embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit of the present invention, and it goes without saying that the present invention includes equivalents thereof. For example, the following modifications are possible.

In the nonwoven fabric 10 of the above-described embodiment, the manifested crimp fiber 11 is formed of a single component (e.g., PET), but this is not limited thereto and may be formed, for example, of a two-component material.

The diaper 1 in the above-described embodiment includes two sheets (top sheet 51 and second sheet 52) closer to the skin than the absorbent body 53, and nonwoven fabric 10 is used for the second sheet 52, but this is not limited to the above. For example, there may be only one sheet closer to the skin than the absorbent body 53. In this case, nonwoven fabric 10 may be used for that sheet.

1. Pants-type disposable diapers (absorbent articles)
1A Ventral waist portion 1B Crotch portion 1C Back waist portion 10 Nonwoven fabric 11 Visible crimped fiber 12 Arc portion 13 Circle 20 Crotch exterior portion 30 Front body portion 30es Ventral side joint portion 30eu Top end 31 Ventral inner layer sheet 33 Ventral outer layer sheet 33f Folded portion 34 Ventral waist elastic member 35 Waist elastic member 36 Leg elastic member 40 Rear body portion 40es Back side joint portion 40eu Top end 41 Back inner layer sheet 43 Back outer layer sheet 43f Folded portion 44 Back waist elastic member 45 Waist elastic member 46 Leg elastic member 50 Absorbent body 51 Top sheet (sheet member)
51a Hole 52 Second sheet (non-woven fabric)
53 absorbent body 53a upper layer core 53b lower layer core 54 back sheet BH waist opening LH leg opening

Claims (12)

A nonwoven fabric for use in an absorbent article, comprising:
A plurality of apparently crimped fibers are included,
The fabric has a plurality of arcuate portions formed of one or more of the apparently crimped fibers and visible from the surface,
When the average fiber length of the apparently crimped fibers is L and the average circumferential length of a circle passing through the three points on the circular arc portion is S,
S≦2×L
A nonwoven fabric characterized by satisfying the above. 2. The nonwoven fabric of claim 1,
S≦L
The nonwoven fabric further satisfies the above. The nonwoven fabric according to claim 1 or 2,
The apparently crimped fibers are bonded to each other with an adhesive.
A nonwoven fabric characterized by: The nonwoven fabric according to claim 3,
At least a portion of the arc portion is composed of a plurality of the manifested crimp fibers bonded to each other by the adhesive.
A nonwoven fabric characterized by: The nonwoven fabric according to any one of claims 1 to 4,
The fineness of the apparently crimped fiber is less than 30 denier.
A nonwoven fabric characterized by: The nonwoven fabric according to any one of claims 1 to 5,
The content of the apparently crimped fibers is greater than 80% by weight.
A nonwoven fabric characterized by: The nonwoven fabric according to any one of claims 1 to 6,
The fiber density is less than 0.065 g/ ^cm3 .
A nonwoven fabric characterized by: The nonwoven fabric according to any one of claims 1 to 7,
The average radius of the circle is smaller than the thickness of the nonwoven fabric.
A nonwoven fabric characterized by: The nonwoven fabric according to any one of claims 1 to 8,
On the surface, an area of a region other than the circular region is larger than a total area of the circular regions surrounded by the plurality of circles.
A nonwoven fabric characterized by: The nonwoven fabric according to any one of claims 1 to 9,
The absorbent article comprises:
An absorbent that absorbs liquid;
A sheet member provided closer to the skin than the absorbent body and having a plurality of holes penetrating in a thickness direction;
Equipped with
disposed between the sheet member and the absorbent body;
A nonwoven fabric characterized by: 11. The nonwoven fabric of claim 10,
A circle among the plurality of circles at least partially overlaps with a hole in the sheet member,
Another circle does not overlap with the hole in the sheet member.
A nonwoven fabric characterized by: An absorbent article comprising an absorbent body that absorbs liquid and a nonwoven fabric provided closer to the skin than the absorbent body,
The nonwoven fabric is
A plurality of apparently crimped fibers are included,
The fabric has a plurality of arcuate portions formed of one or more of the apparently crimped fibers and visible from the surface,
When the average fiber length of the apparently crimped fibers is L and the average circumferential length of a circle passing through the three points on the circular arc portion is S,
S≦2×L
An absorbent article characterized by satisfying the above.

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