JP7437870B2 - absorbent articles - Google Patents

Description

The present invention relates to absorbent articles.

Nonwoven fabrics are often used as topsheets for absorbent articles such as disposable diapers and sanitary napkins. Techniques are known for imparting various functions to this nonwoven fabric, such as texture such as softness and cushioning properties.

For example, a nonwoven fabric has been proposed that is resistant to crushing and has good cushioning properties, and that allows liquid to flow easily to increase the rate of absorption from through holes (for example, Patent Document 1). The nonwoven fabric of Patent Document 1 has a first protrusion that protrudes toward a first surface when the sheet-like nonwoven fabric is viewed from above, and a second protrusion that protrudes toward a second surface that is opposite to the first surface. It has a section. The first protrusions and the second protrusions are arranged continuously in different directions intersecting the nonwoven fabric in a plan view, and through holes are provided at the tops of the plurality of second protrusions. Since the fibers around the holes are oriented toward the center of the holes, they are resistant to collapse, have good cushioning properties, and allow liquid to flow easily.

Japanese Patent Application Publication No. 2013-133574

User requirements for absorbent articles are becoming ever more demanding. There is a need for absorbent articles with even shorter absorption times and liquid flow distances.

The present invention relates to an absorbent article that can further shorten absorption time and liquid flow distance.

The present invention is an absorbent article comprising a liquid-permeable topsheet having a skin-contacting surface and an absorbent body disposed on the non-skin-contacting surface side of the topsheet, the topsheet comprising: It is made of a nonwoven fabric having a plurality of ridges arranged to protrude toward the skin-contacting surface, and a bottom provided between adjacent ridges, and each of the plurality of ridges has a top and a top. a supporting wall portion, the wall portion extending substantially perpendicularly to the bottom portion, and a penetrating wall extending from the skin contacting surface side toward the non-skin contacting surface side. The present invention relates to an absorbent article having apertures formed therein.

The absorbent article according to the present invention can further shorten absorption time and liquid flow distance.

1 is a plan view showing the basic configuration of a disposable diaper as an embodiment of an absorbent article of the present invention. FIG. 2 is a cross-sectional view taken along line I-I' in FIG. 1. FIG. It is a partial perspective view showing an example of a nonwoven fabric. 4 is a sectional view taken along line II-II' in FIG. 3. FIG. It is a figure explaining how to obtain the angle of a wall part area. 4 is a sectional view taken along the line III-III' in FIG. 3. FIG. 4 is a sectional view taken along line IV-IV' in FIG. 3. FIG. FIG. 2 is an explanatory diagram schematically showing a part of a preferable manufacturing method for a nonwoven fabric used in the absorbent article of the present embodiment, in which (A) a fiber web is arranged on a male support material, and the female support material is It is an explanatory view showing a process of inserting the fiber web into a male support material from above, (B) is an explanatory view showing a process of shaping the fiber web by blowing the first hot air from above the female support material, and (C ) is an explanatory diagram showing a step of removing the support female material and blowing second hot air from above the shaped fiber web to fuse the fibers together. FIG. 3 is a plan view of a male support member. It is a side view explaining the upper end part of the protrusion of a support body male member. It is a top view which shows an example of a support body female member. FIG. 3 is a plan view showing an example of a state in which a male support member and a female support member are combined. FIG. 7 is a plan view showing another example of a state in which a male support member and a female support member are combined. It is a figure explaining the measuring method of fiber orientation, (A) is a SEM image of fiber, (B) is an OHP fiber image, (C) is a power spectrum, and (D) is an average amplitude. FIG.

Hereinafter, absorbent articles according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential to the solution of the invention. .

1 and 2 show the basic structure of a disposable diaper 10 (hereinafter also simply referred to as "diaper 10"), which is an embodiment of the absorbent article of the present invention. As shown in FIGS. 1 and 2, the diaper 10 includes a liquid-permeable topsheet 2 forming a skin-contacting surface, a backsheet 3 disposed on the non-skin-contacting surface side of the topsheet 2, The absorbent body 4 is arranged between the two sheets 2 and 3. The topsheet 2 and the absorbent body 4 are integrated by, for example, an adhesive such as a hot-melt adhesive, heat sealing, or the like.

Note that the skin-contact surface is the surface of the diaper 10 or its constituent members that faces the wearer's skin when worn, and the non-skin-contact surface refers to the side opposite to the wearer's skin when worn. It is a surface that is directed towards. The backsheet 3 can be formed using a material commonly used for backsheets of absorbent articles. For example, a liquid-impermeable resin film, a water-repellent resin film, a laminate sheet of a resin film and a nonwoven fabric, or, in some cases, a liquid-permeable nonwoven fabric is used as the back sheet 3.

The diaper 10 has a longitudinal direction Y that coincides with the wearer's front-rear direction when worn, and a width direction have. The diaper 10 also includes a ventral part A disposed on the ventral side of the wearer when worn, a dorsal part B disposed on the wearer's dorsal side when worn, and a ventral part A and dorsal part B. It has a crotch portion C located in between in the longitudinal direction Y. The diaper 10 is an expandable disposable diaper, and fastening tapes 7 are provided on both side edges of the back side part B. A landing zone 8 to which the fastening tape 7 is fixed is provided on the outer surface of the abdominal part A.

The absorbent core 4 in the diaper 10 includes an absorbent core 4a and a core wrap sheet 4b surrounding the absorbent core 4a. The absorbent core 4a can be composed of, for example, a stack of absorbent fibers such as pulp fibers, or a mixed stack of absorbent fibers and a water-absorbing polymer. Examples of the absorbent fibers include pulp fibers, rayon fibers, cotton fibers, and cellulose-based hydrophilic fibers such as cellulose acetate.

In addition to cellulose-based hydrophilic fibers, fibers made of synthetic resins such as polyolefins, polyesters, and polyamides made hydrophilic with a surfactant or the like may also be used. For example, tissue paper or water-permeable nonwoven fabric is used as the core wrap sheet 4b. One core wrap sheet 4b may wrap the entire absorbent core 4a, or two or more sheets may be combined to wrap the absorbent core 4a.

On both sides of the diaper 10 in the longitudinal direction Y, sheets 5 for forming three-dimensional gathers having elastic members 5a are arranged. Due to the contraction of the elastic member 5a, three-dimensional gathers that stand up toward the skin of the wearer are formed in the crotch area C in the worn state. In addition, leg elastic members 6 are disposed in a stretched state at a portion of the crotch C that is disposed around the legs. By contraction of the leg elastic members 6, leg gathers are formed in the crotch C in the worn state to improve the fit around the wearer's legs.

The topsheet 2 in the diaper 10 of this embodiment is made of a nonwoven fabric 1 having a linear uneven structure extending in one direction on its skin contact surface. Although the extending direction of the uneven structure in the topsheet 2 matches the longitudinal direction Y of the diaper 10, it does not necessarily have to match. The uneven structure may extend in the width direction X of the diaper 10 in some cases.

The fiber material that can be used for the nonwoven fabric 1 is not particularly limited. Specifically, polyolefin fibers such as polyethylene (PE) fibers and polypropylene (PP) fibers; fibers made solely of thermoplastic resins such as polyethylene terephthalate (PET) and polyamide; structures such as core-sheath type and side-by-side type. Examples include composite fibers. Examples of such composite fibers include fibers with a core-sheath structure in which the sheath component is PE or low melting point PP. Typical examples of fibers with a core-sheath structure include fibers with a core-sheath structure such as PET (core) and PE (sheath), PP (core) and PE (sheath), PP (core) and low melting point PP (sheath), etc. can be mentioned.

The fiber material preferably includes polyolefin fibers such as PE fibers and PP fibers, PE composite fibers, or PP composite fibers. The PE composite fiber has a composite composition containing PET and PE, and preferably contains PET and low melting point PP. More specifically, examples include PET (core) and PE (sheath), and PET (core) and low melting point PP (sheath). These fibers can be used alone or in combination of two or more to constitute a nonwoven fabric. Moreover, the nonwoven fabric may contain fibers other than thermoplastic fibers.

An example of the nonwoven fabric 1 constituting the topsheet 2 will be described below with reference to FIGS. 3 to 7. The nonwoven fabric 1 shown in FIG. 3 has a plurality of ridges 12 adjacent to each other in the first direction (width direction It extends continuously along (longitudinal direction Y in the diaper 10).

Furthermore, the nonwoven fabric 1 has a plurality of saddle portions 16 provided between adjacent ridge portions 12 so as to protrude from the bottom portion 14 toward the skin contacting surface side. The saddle 16 extends in a direction (second direction) perpendicular to the direction in which the ridges 12 extend (second direction) so as to connect adjacent ridges 12 . The saddle 16 is upwardly convex in a cross section along the direction in which the ridges 12 extend (see FIG. 7), and is downwardly convex in a cross section along a direction perpendicular to the direction in which the ridges 12 extend (see FIG. 6). It is convex. That is, the saddle portion 16 has a shape that is curved in opposite directions in two orthogonal directions in the thickness direction of the nonwoven fabric 1. Note that the nonwoven fabric 1 may be configured without the saddle portion 16.

In this embodiment, the bottom portion 14 corresponds to a region surrounded by the ridge portion 12 and the saddle portion 16. Each of the bottom parts 14 is provided with an opening 15 in at least a portion thereof, which penetrates in the thickness direction from the skin-contacting surface side to the non-skin-contacting surface side. The openings 15 are pores intentionally formed in the nonwoven fabric 1, unlike the fine pores formed between the fibers, and have a much larger area than the fine pores formed between the fibers. There is. The size of the opening 15 can be appropriately selected depending on the width of the bottom 14, etc., but it is desirable that the opening 15 has an area of at least 1 mm ² or more.

In this embodiment, the opening 15 is formed in substantially the entire area of the bottom portion 14 surrounded by the ridge portion 12 and the saddle portion 16, and has a rectangular shape in a plan view. Note that the shape of the opening 15 is not limited to a rectangular shape, and it is also possible to adopt various shapes such as a circular shape, for example. Further, it is also possible to have a configuration in which the opening 15 is formed only in a part of the bottom part 14 surrounded by the ridge part 12 and the saddle part 16. In this case, the position is not particularly limited and can be arbitrarily set. An opening 15 can be formed at the position.

As shown in FIG. 4, the plurality of ridges 12 protrude from the bottom 14 toward the skin contact surface and are arranged in one direction. Thereby, diffusion of liquid in the direction in which the ridges 12 are adjacent to each other can be suppressed. The bottom portion 14 of the nonwoven fabric 1 is the non-skin contact surface side. The ridges 12 have the same height along the continuous direction. In this specification, "equivalent" in height means that the height measured using a microscope VHX900 (manufactured by Keyence Corporation) is within a range of 0.8 times or more and 1.2 times or less of the measured average value. It means to be.

Each ridge 12 has a top (hereinafter referred to as "top region 12a") and a pair of walls (hereinafter referred to as "wall region 12b") that support the top region 12a. The wall region 12b is formed to extend substantially perpendicularly to the bottom portion 14. Preferably, the entire wall region 12b extends substantially perpendicular to the bottom 14, but only a portion of the wall region 12b may extend substantially perpendicular to the bottom 14.

In this specification, "substantially perpendicular" refers not only to the case where the angle θ shown in FIG. . Here, the angle θ means the intersection angle of the wall region 12b with respect to the plane of the nonwoven fabric 1. Specifically, as shown in FIG. 5, in a cross section perpendicular to the direction in which the ridges 12 extend (II-II' cross section shown in FIG. 2), the center line SL of the wall region 12b and the adjacent bottom portion 14 are It refers to the internal angle of the angle formed by the straight line HL connecting the lower surfaces. This angle θ can be determined by observing a micrograph of the II-II' cross section.

In the example shown in FIG. 5, since the wall region 12b extends substantially linearly between the top region 12a and the bottom 14, the entire region of the wall region 12b is against the skin contacting surface of the nonwoven fabric 1. It is installed almost vertically. However, the present invention is not limited to this, and the wall region 12b may extend in a curved or wavy manner between the top region 12a and the bottom portion 14. In this case, the angle θ is specified by using a line connecting the boundary point between the top region 12a and the wall region 12b and the boundary point between the bottom portion 14 and the wall region 12b as the center line SL. .

In the direction perpendicular to the direction in which the ridges 12 extend, the ridges 12 and the saddles 16 are arranged alternately, as shown in FIG. 6 . As shown in FIGS. 6 and 7, the saddle portion 16 has a height smaller than the ridge portion 12 from the bottom portion 14, that is, has a lower height than the ridge portion 12. Specifically, the distance in the thickness direction from the bottom portion 14 to the saddle portion 16 is about 0.1 to 10 times the distance in the thickness direction from the top region 12a to the saddle portion 16. Further, the height difference (Δh) between the ridge portion 12 and the saddle portion 16 can be approximately 0.5 to 7 mm.

In a cross section where the saddle portion 16 is downwardly convex (for example, FIG. 6), the curvature of the saddle portion 16 depends on the distance d between adjacent top regions 12a. The smaller the distance d between adjacent top regions 12a, the greater the curvature of the saddle 16. In this case, the radius of curvature of the saddle portion 16 can be confirmed by measuring the radius of curvature of the edge of the saddle portion 16 using, for example, the above-mentioned microscope. The radius of curvature of the edge of the saddle portion 16 can be determined, for example, by assuming a virtual surface on the edge of the saddle portion 16 from the skin-contacting surface side and measuring the radius of a circle that is in contact with the virtual surface.

The radius of curvature of the saddle 16 can also be determined in a cross section where the saddle 16 is upwardly convex (for example, FIG. 7). In this case, the radius of curvature of the edge of the saddle 16 can be determined by assuming an imaginary surface at the edge of the saddle from the non-skin contact surface side and measuring the radius of a circle that is in contact with the imaginary surface. Such a saddle portion 16 can be formed, for example, when manufacturing the nonwoven fabric 1 by the method described below.

The distance in the thickness direction from the top region 12a to the saddle 16 can be determined as follows. That is, the nonwoven fabric 1 is installed so that the bottom part 14 is in contact with the surface of a horizontal table, and the height from the horizontal table to the top region 12a and the saddle part 16 are Measure the height up to. The difference between the height from the horizontal platform thus obtained to the top region 12a and the height to the saddle 16 corresponds to the distance from the top region 12a to the saddle 16 in the thickness direction. The above-mentioned microscope is used to measure the height from the horizontal platform. Such a saddle portion 16 can be obtained, for example, by a method for manufacturing the nonwoven fabric 1 described later.

As shown in FIG. 7, the saddle portion 16 has a pair of side portions 16b. This side 16b, like the wall region 12b of the ridge 12, is substantially perpendicular to the bottom 14. Therefore, the flow of liquid toward the bottom portion 14 is promoted in the saddle portion 16 as well as in the ridge portion 12. In particular, since the ridges 12 are higher than the saddle 16, liquid that has come into contact with the skin-contacting surface is easily guided from the ridges 12 to the apertures 15 in the bottom 14 via the saddle 16. Further, when the direction in which the ridges 12 extend coincides with the longitudinal direction of the diaper 10, the liquid damming effect by the saddle 16 leads to an improvement in the liquid leakage prevention effect in the front-rear direction.

In the wall region 12b of the ridge 12, the fibers are oriented in the thickness direction of the nonwoven fabric. "The fibers are oriented in the thickness direction of the nonwoven fabric" means that the fibers are oriented substantially perpendicular to the plane of the nonwoven fabric 1 (skin contact surface and non-skin contact surface). Since the fibers in the wall region 12b are oriented substantially vertically, the ridges 12 are not easily deformed in the height direction even when subjected to a pressing force, and can maintain their shape.

Here, a method for measuring fiber orientation will be described with reference to FIG. 14.
Regarding the orientation of the fibers in the wall region 12b, the cross section along the direction perpendicular to the direction in which the ridges 12 extend (II-II' cross section shown in FIG. 4), and the cross section along the direction in which the ridges 12 extend ( The orientation angle θ _ori and orientation strength are examined for both cross sections IV-IV' shown in FIG. In both of these cross sections, if the orientation angle θ _ori is 60° or more and 120° or less, and the orientation strength is 1.05 or more, "the fibers are oriented in the thickness direction of the nonwoven fabric" ( In other words, "the fibers are oriented substantially perpendicular to the plane of the nonwoven fabric."

First, the fibers in the wall region 12b in a predetermined cross section are photographed using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.) to obtain a SEM image as shown in FIG. 14(A). When photographing, adjust the magnification (100 to 300 times) so that you can measure 10 or more fibers.

The obtained SEM image is printed and the fibers are traced on an OHP sheet to obtain an OHP fiber image as shown in FIG. 14(B). The OHP fiber image is read with a scanner in black-and-white binary mode and imported into a personal computer.

The binarized and captured image is Fourier transformed using a fiber orientation analysis program to obtain a power spectrum as shown in FIG. 14(C). As the fiber orientation analysis program, (surface fiber orientation analysis program FiberOri8single03.exe (published by Toshiharu Emae, Paper Science Laboratory, Department of Biomaterials Science, Graduate School of Agriculture and Life Sciences, University of Tokyo)) is used. This is approximated to an ellipse to obtain an angular distribution diagram of the average amplitude as shown in FIG. 14(D). The orientation angle and orientation intensity can be determined from this angle distribution map. θ _ori in the angle distribution diagram shown in FIG. 14(D) is the orientation angle, and the ratio (LA/SA) between the major axis LA and the minor axis SA in the approximate ellipse is the orientation intensity.

The orientation angle θ _ori indicates the angle at which the fibers are most oriented, and the orientation strength (LA/SA) indicates the strength at the orientation angle θ _ori . In the measurement of the wall region 12b, if the orientation angle θ _ori is 60° or more and 120° or less, it is determined that the fibers are oriented substantially vertically in the observed cross section. The orientation angle θ _ori is preferably 75° or more and 105° or less. The larger the orientation strength value, the more aligned the fibers are. When the orientation strength is 1.05 or more, it is determined that the orientation is oriented. Measurements are made for three regions in the cross section, and the average value is taken as the orientation angle and orientation strength of the sample.

The above-mentioned fiber orientation is a concept consisting of the orientation angle and orientation strength of the fibers. The orientation angle of fibers is a concept that indicates the direction in which a plurality of fibers having different orientation directions are coordinated as a whole. Therefore, it can be said that the shape of the fiber aggregate is quantified. The orientation strength of fibers is a concept that represents the amount of fibers exhibiting an orientation angle. When the orientation angle is less than 1.05, it can be said that there is almost no orientation, and when it is 1.05 or more, it can be said that there is orientation.

The orientation _angle of the fibers in the wall region 12b is preferably 60° or more, more preferably 75° or more, and is preferably 120° or less, more preferably 105° or less. preferable. The orientation strength of the fibers in the wall region 12b is preferably 1.05 or more, more preferably 1.2 or more.

The nonwoven fabric 1 has a hollow region 18 on the non-skin contact surface side of the ridge portion 12, as shown in FIG. The term "hollow region" as used herein refers to a space that is not substantially filled with fibers of the nonwoven fabric, and specifically means that the fiber density determined by the method described below is less than 10 fibers/ ^mm2 . Point. The fiber density in the hollow region 18 is preferably as small as possible. The hollow region 18 acts as a continuous flow path in the direction in which the ridges 12 extend, and promotes the movement of liquid to the absorbent body 4 in the diaper 10. By having the hollow region 18, the nonwoven fabric 1 has improved cushioning properties and has a structure that is not easily crushed in the thickness direction. Moreover, the hollow region 18 also has the effect of suppressing the return of liquid to the skin contact surface.

The fiber density can be measured by observing the cross section of the nonwoven fabric 1 by the following method. The nonwoven fabric 1 is cut in the thickness direction so as to pass through the region to be measured (for example, between the wall regions 12b). The cut surface is observed under magnification using a scanning electron microscope (JCM-6000Plus, manufactured by JEOL Ltd.), and the cross sections of the cut fibers within a certain area of the cut surface are counted. The magnification observation is adjusted to a magnification (150 times or more and 500 times or less) that allows the measurement of 30 to 60 fiber cross sections. Next, it is converted to the number of cross sections of fibers per 1 mm ² and this is defined as the fiber density (fibers/mm ² ). The results of measurements at three locations are averaged to determine the fiber density of the sample.

Since the diaper 10 of this embodiment includes the above-mentioned nonwoven fabric 1 as the top sheet 2, during use, liquid can penetrate into the interior from the skin-contacting surface side in a short time, and has excellent liquid drawing properties. ing. Moreover, even if the permeated liquid heads toward the skin-contacting surface, there is little risk of it flowing out from the skin-contacting surface. In other words, the diaper 10 of this embodiment uses the nonwoven fabric 1 as the top sheet 2, which has the wall region 12b standing approximately perpendicular to the bottom 14 and the openings 15 provided in the bottom 14. This makes it possible to further shorten the absorption time and liquid flow distance compared to the case where the nonwoven fabric of Patent Document 1 is used as the top sheet. These characteristics can be confirmed by measuring the absorption time, liquid flow distance, and liquid return amount using the method described below.

That is, in the nonwoven fabric of Patent Document 1, each first protrusion is formed in a truncated cone shape or a hemispherical shape with a rounded top (paragraph [0012] of Patent Document 1). On the other hand, in the nonwoven fabric 1 according to the present embodiment, the inclination angle of the wall regions 12b in the ridges 12 is steeper than in Patent Document 1, and each wall region 12b is erected substantially perpendicularly to the bottom 14. Thereby, the liquid flowing on the skin contact surface can be dammed by each ridge 12 and effectively guided toward the bottom 14. In addition, the nonwoven fabric 1 according to the present embodiment has the openings 15 provided in the bottom 14, so that the liquid guided to the bottom 14 by the wall region 12b of the ridge 12 can be further guided toward the absorbent body 4. becomes possible. In this way, in the nonwoven fabric 1 according to the present embodiment, the wall region 12b standing approximately perpendicularly to the bottom portion 14 and the openings 15 provided in the bottom portion 14 synergistically interact with each other. , compared to the nonwoven fabric of Patent Document 1, it is possible to further shorten the absorption time and liquid flow distance.

In particular, when the extending direction of the ridges 12 coincides with the longitudinal direction of the diaper 10, this movement of liquid leads to an improved side leakage prevention effect. In addition, by providing the saddle 16 to connect adjacent ridges 12, it is possible to exert a liquid damming effect not only by the ridges 12 but also by the saddle 16, which improves the absorption time and liquid flow distance. This makes it possible to further shorten the time period. Furthermore, since the saddle portion 16 is formed to be lower than the ridge portion 12, the flow of liquid from the ridge portion 12 to the saddle portion 16 to the opening 15 to the absorbent body 4 is promoted, thereby increasing the absorption time and the liquid flow distance. can be further shortened.

In addition, the nonwoven fabric 1 according to the present embodiment has a bulky structure in which the distance from the bottom 14 to the top region 12a is large because the wall regions 12b of the ridges 12 are erected substantially perpendicularly to the bottom 14. This becomes nonwoven fabric 1. Therefore, in the nonwoven fabric 1 according to the present embodiment, the distance between the wearer's skin and the absorbent body 4 is large compared to the nonwoven fabric of Patent Document 1, and the liquid absorbed by the absorbent body 4 is transferred to the skin contact surface. It also has the effect of making it difficult to return.

In particular, the nonwoven fabric 1 according to the present embodiment has high cushioning properties and is difficult to collapse because the fibers in the wall region 12b are oriented in the thickness direction of the nonwoven fabric 1. For this reason, it becomes possible to maintain the distance between the wearer's skin and the absorbent body 4 more effectively during wear, and the effect of suppressing liquid return becomes more excellent. Further, since the ridge portion 12 has the hollow region 18 on the non-skin contact surface side, it becomes possible to suppress liquid return from the absorbent core 4 more effectively.

A preferred embodiment of the method for manufacturing the nonwoven fabric 1 will be described below with reference to FIGS. 8 to 11.
In manufacturing the nonwoven fabric 1 of this embodiment, first, as shown in FIG. Press. As shown in FIG. 9, the male support member 120 has protrusions 121 arranged at intervals in one direction and a direction perpendicular thereto. As shown in FIG. 10(A), the protrusion 121 has a sharp portion 124 over the entire upper end portion. Note that the protrusion 121 provided on the male support member 120 is not limited to the shape shown in FIG. 121A, or a protrusion 121B having a prismatic protrusion 124B on a part of its upper end, as shown in FIG. 10(C). As shown in FIG. 11, the female support member 130 is provided with a plurality of protrusions 131 that are continuous in one direction.

The male support member 120 has a plurality of protrusions 121 corresponding to positions where the bottom portion 14 surrounded by the ridge portions 12 and the saddle portions 16 of the nonwoven fabric 1 is shaped. A recess 122 is formed between adjacent protrusions 121 corresponding to the position where the ridge 12 is shaped. As a result, the male support member 120 has an uneven shape, and the protrusions 121 and the recesses 122 are alternately arranged in different directions in plan view. The base 123 of the recess 122 has a structure through which hot air can pass.

In this embodiment, the support body for producing the nonwoven fabric 1 has a machine flow direction (MD direction) corresponding to the Y direction of the nonwoven fabric 1 and a width direction (CD direction) orthogonal to the machine flow direction corresponding to the X direction of the nonwoven fabric 1. do. However, "different directions" are not limited to the Y direction and the X direction. If the height of the projections 121 of the male support member 120 is 3 mm or more, it is possible to produce a nonwoven fabric 1 with a cushioned feel. The height of the protrusion 121 is more preferably 5 mm or more, and most preferably 7 mm or more.

The protrusion 121 may be either a prism or a cylinder. In the illustrated example, the nonwoven fabric 1 has a rectangular shape in the MD direction in plan view, but it can also have a diamond shape. It is preferable that the protrusion 121 is a prismatic column and square in plan view. In this case, the fibers enter into the support male material 120, the shape of the nonwoven fabric 1 is maintained, and the thickness of the nonwoven fabric 1 is easily ensured.

Considering the ease with which the shape of the nonwoven fabric 1 can be maintained, it is preferable that the area of the top surface of one of the protrusions 121 in plan view is 3 mm ² or more. Moreover, it is preferable that the distance between adjacent protrusions 121 is 2 mm or more in plan view. In this case, a space for effectively pushing the fibers can be secured.

The female support member 130 has a protrusion 131 that corresponds to the recess 122 of the male support member 120 and continues in one direction in plan view. A concave portion 132 corresponding to the protrusion 121 of the male support member 120 is formed between adjacent protrusions 131 . As a result, the female support member 130 has an uneven shape, and projections 131 and recesses 132 are alternately arranged.

The distance between the protrusions 131 on the female support member 130 is wider than the width of the protrusions 121 on the male support member 120. The distance between the protrusions 131 is such that the fiber web 110 is sandwiched between the protrusions 121 of the male support member 120 and the protrusions 131 of the female support member 130, so that the wall region 12b in which the fibers are oriented in the thickness direction can be suitably shaped. It is set as appropriate. The protrusions 131 on the female support member 130 need to be inserted between the protrusions 121 on the male support member 120. For this reason, it is preferable that the protrusion 131 has a length of 0.5 mm or more.

The pitch of the protrusions 131 is set so that the protrusions 121 on the male support member 120 and the recesses 132 on the female support member 130 fit together to obtain a continuous nonwoven fabric 1 in the plane direction. Specifically, the pitch of the protrusions 131 is preferably 1 mm or more longer than the length of one side of the protrusions 121 on the male support member 120 in plan view. Note that when the top surface shape of the projection 121 is circular or oval, the length of one side of the top surface of the projection 121 is the diameter or length of the major axis.

The fiber web 110 shown in FIG. 8(A) is supplied from a card machine (not shown) to a position where the web is shaped. The fibrous web includes thermoplastic fibers that have been treated to be hydrophilic. A support female member 130 is pushed in from above the fiber web 110, as shown in FIG. 8(B). At this time, the protrusion 121 of the male support member 120 and the recess 132 of the female support member 130 fit together, and the recess 122 of the male support member 120 and the protrusion 131 of the female support member 130 fit together. The male support member 120 and the female support member 130 are combined as shown in FIG. 12. In FIG. 12, the fiber web is omitted.

Unlike nonwoven fabric, the fiber web 110 has a high degree of freedom in fiber movement. Therefore, when the fibers of the fiber web 110 are sandwiched between the male support material 120 and the female support material 130, they are oriented in a predetermined direction depending on the state.

As shown in FIG. 8(B), in a region 112b sandwiched between the side surface of the protrusion 121 on the male support member 120 and the side surface of the protrusion 131 on the female support member 130, the fibers are oriented in the thickness direction. On the other hand, in the region 112a between the recess 122 of the male support member 120 and the end surface of the protrusion 131 of the female support member 130, the fibers are oriented in the plane direction. Since the support female material 130 is pressed, the fibers oriented in the plane direction in the region 112a are denser than in the other region 112b.

As shown in FIG. 12, the protrusions 131 of the female support member 130 do not enter into the portions 122a corresponding to the recesses 132 on the female support member 130 among the recesses 122 between the adjacent protrusions 121 on the male support member 120. . Therefore, in the fiber web (not shown), the fibers are pulled within a region 122a surrounded by the protrusion 121 of the male support member 120 and the protrusion 131 of the female support member 130. In this way, regions with different fiber orientations are formed, forming a fiber layer corresponding to the saddle portion 16.

In this state, it is preferable to blow the first hot air W1 toward the fiber web 110 from the support female member 130 side, as shown in FIG. 8(B). As a result, the fiber web 110 is fused to such an extent that the uneven shape of the nonwoven fabric 1 can be maintained. In the fiber web 110, the fibers are extremely loosely fused together. Arrows in the drawing schematically indicate the flow of the first hot air W1.

In a region 112b between the wall surface of the protrusion 121 of the male support material 120 and the wall surface of the protrusion 131 of the female support material 130, a wall region 12b in which fibers are oriented in the thickness direction is formed. In the region 114 between the end surface of the protrusion 121 and the base of the recess 132, the first hot air W1 fuses the fibers to such an extent that the fibers can maintain their shape in the planar direction. As a result, a fiber layer corresponding to the bottom portion 14 is formed. An opening 15 is formed in the bottom portion 14 by the sharp portion 124 of the protrusion 121 . The fiber layer formed in the region 112a between the base 123 of the recess 122 and the end surface of the protrusion 131 is smooth with less fusion of fibers because the protrusion 131 separates the hot air. This forms a fiber layer corresponding to the top region 12a.

The temperature of the first hot air W1 is set to a temperature higher than the melting point so that the thermoplastic fiber can maintain its shape in the thickness direction and in the plane direction. Considering the general fiber materials used in this type of manufacturing method, the difference between the temperature of the first hot air W1 and the melting point of the thermoplastic fiber is preferably 70°C or less, and 5°C or more and 50°C or less. It is more preferable that there be.

The speed of the first hot air W1 is preferably 2 m/s or more, more preferably 3 m/s or more, from the viewpoint of effective fusion. Further, the speed of the first hot air W1 is preferably 100 m/s or less, more preferably 80 m/s or less, from the viewpoint of making the apparatus compact. In this way, the fiber web 110 is thermally fused and held in an uneven shape.

Next, the support female member 130 is removed, and the second hot air W2 is blown to further fuse the fibers to each other so that each fiber of the fibrous web 110 having the uneven shape can be appropriately fused. As shown in FIG. 8(C), similarly to the first hot air W1, it is preferable to blow the second hot air W2 onto the fibrous web 110 from the side of the nonwoven fabric 1 that is the non-skin contacting surface. The temperature of the second hot air W2 is set to a temperature higher than the melting point so that the thermoplastic fiber can maintain its shape in the thickness direction and the plane direction. Considering common fiber materials used in this type of manufacturing method, the difference between the temperature of the second hot air W2 and the melting point of the thermoplastic fiber is preferably 70°C or less, and is preferably 5°C or more and 50°C or less. It is more preferable that there be.

The wind speed of the second hot air W2 is preferably 2 m/s or more, more preferably 3 m/s or more, although it also depends on the height of the protrusion 121 of the male support member 120. Thereby, sufficient heat transfer to the fibers can be achieved, the fibers can be fused together, and the uneven shape can be sufficiently fixed. The wind speed of the second hot air W2 is preferably 100 m/s or less, more preferably 80 m/s or less. This suppresses excessive heat transfer to the fibers and provides a nonwoven fabric 1 with a good texture.

Note that by reducing the surface roughness of the female support member, it is possible to omit the step of blowing the first hot air W1. By reducing the surface roughness, the female support member can be removed in the process of blowing the second hot air W2 without having unfused fibers cling to it. That is, after producing the web, it is possible to fit the male support member and the female support member together, remove the female support member as is, and treat the web with the second hot air W2. This makes processing easier.

Examples of thermoplastic fibers include those commonly used as materials for nonwoven fabrics. For example, it may be a fiber made of a single resin component or a composite fiber made of a plurality of resin components. Examples of composite fibers include core-sheath type and side-by-side type.

When using a composite fiber containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, a core-sheath composite fiber in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web 110 is set to a low melting point component. It is preferable that the temperature is higher than the melting point of the component and lower than the melting point of the high melting point component. More preferably, the temperature is higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component, and even more preferably, the temperature is 5°C or more higher than the melting point of the low melting point component and 20°C or more lower than the melting point of the high melting point component. . In addition, from the viewpoint of elasticity, among the core-sheath composite fibers, the more the core has a high melting point, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio.

As explained above, the nonwoven fabric 1 is produced. On the side surface of the protrusion 121 of the male support member 120, the fibers of the fiber web 110 are aligned in the thickness direction to form a wall region 12b. At the top of the protrusion 121, a bottom portion 14 in which fibers are oriented in a plane direction and an opening 15 are formed. Further, a saddle portion 16 is formed between the openings 15 adjacent to each other in the direction in which the ridge portion 12 extends. Further, the base 123 of the recess 122 is formed with a top region 12a in which fibers are oriented in the plane direction.

In this embodiment, the obtained nonwoven fabric 1 is assembled into the diaper 10 so that the lower surface in FIG. 8(C) is the skin-contacting surface and the opposite surface is the non-skin-contacting surface. It is. That is, the skin-contacting surface of the nonwoven fabric 1 is the side on which the male support material 120 is disposed, and the non-skin-contacting surface is the side on which the first hot air W1 and the second hot air W2 are blown. Therefore, due to the difference in the amount of blowing of the first hot air W1 and the second hot air W2, the amount of fibers fused to each other on the bottom part 14 of the non-skin contacting surface is greater than that of the top region 12a of the skin contacting surface. However, the nonwoven fabric 1 may be incorporated into the diaper 10 in the opposite way, that is, so that the lower surface of the nonwoven fabric 1 in FIG. 7(C) becomes the non-skin contacting surface.

Furthermore, due to the small amount of heat, the surface of the top region 12a on the skin-contacting surface side is smoother and feels better to the touch than the surface of the bottom portion 14 on the non-skin-contacting surface side. Even if the step of blowing the first hot air W1 is omitted, the same effect can be obtained depending on the distance from the second hot air W2.

Furthermore, by fitting the supports together, the fibers on the female support member 130 side (the fibers forming the bottom portion 14 on the non-skin contacting surface side of the nonwoven fabric 1) are pulled toward the male support member 120. Therefore, the amount of fibers in the bottom part 14 on the non-skin contacting surface formed at the top of the protrusion 121 of the male support 120 is smaller than that on the skin contacting surface formed in the base 123 of the recess 122 of the male support 120. It becomes smaller than the top region 12a of .

In the nonwoven fabric manufacturing method of this embodiment, the thickness of the nonwoven fabric 1 is appropriately determined by the heights of the protrusions 121 of the male support member 120 and the protrusions 131 of the female support member 130. For example, increasing the height of the projections increases the apparent thickness of the sheet, and decreasing the height of the projections decreases the apparent thickness of the sheet. Further, when the height of the protrusions is increased, the fiber density of the nonwoven fabric 1 becomes low, and when the height of the protrusions is decreased, the fiber density of the nonwoven fabric 1 becomes high.

In addition, in the manufacturing method described above, the support female member 130 having a plurality of protrusions 131 continuous in one direction was used, but for example, as shown in FIG. It is also possible to change to the support female member 130A having the following. In the support female member 130A used here, a plurality of recesses 132 arranged in a lattice shape in plan view are formed by intersecting protrusions 131A and 131B that are continuous in two orthogonal directions.

That is, the recess 132 is a rectangular area surrounded by a protrusion 131A that continuously extends in one direction and a protrusion 131B that continuously extends in a direction perpendicular to the protrusion 131A. It is formed so as to penetrate through the area. This recess 132 is formed corresponding to the projection 121 so as to receive the projection 121 of the male support member 120. Even when changing to such a female support material 130A, a nonwoven fabric can be manufactured using the same male support material 120 according to the method described with reference to FIG. 8.

Similarly to the example shown in FIG. 8(B), by pushing the female support material 130A into the fiber web 110 on the male support material 120, each protrusion 121 of the male support material 120 is pushed into each recess of the female support material 130A. 132, and the respective protrusions 131A and 131B of the female support member 130A are inserted into the recess 122 of the male support member 120. A plan view of this state is schematically shown in FIG. In FIG. 13, the fiber web is omitted. The fiber web (not shown) is sandwiched between the four wall surfaces of the protrusion 121 of the male support member 120 and the wall surface of the recess 132 of the female support member 130A that surrounds this. As a result, the fibers of the fibrous web 110 are oriented in the thickness direction.

In the female support member 130A used here, only the protrusion 131A extending in one direction presses the fiber web at the end face against the base 123 of the recess 122 of the male support member 120, similar to the example shown in FIG. 8(B). A fiber layer corresponding to the ridges 12 is formed. In the other direction, the fibrous web pressed by the end face of the protrusion 131B within the recess 122a of the male support 120 does not reach the base 123 of the recess 122 of the male support 120, and this region of the fibrous web , becomes a fiber layer corresponding to the saddle portion 16.

The nonwoven fabric 1 obtained as described above is introduced into a manufacturing line for the diaper 10, and becomes the top sheet 2 of the diaper 10 by a known method.

As described above, the nonwoven fabric 1 has an uneven structure consisting of ridges and a bottom, and at least a portion of the bottom is provided with an opening, and the wall area of the ridge is approximately perpendicular to the bottom. be. Since it has such a nonwoven fabric 1 as the topsheet 2, the diaper 10 according to this embodiment can further shorten the absorption time and liquid flow distance.

Next, examples of nonwoven fabrics used in the absorbent article of the present invention will be described, but the present invention is not limited thereto.

[Example 1]
A fiber web was produced using core-sheath type (polyethylene terephthalate (PET)/polyethylene (PE) = 5:5) thermoplastic fibers with a fineness of 1.8 dtex. Thermoplastic fibers have been subjected to hydrophilic treatment. The fiber web was placed on the male support material 120, and as shown in FIG. 8(A), the female support material 130 was pushed into the male support material 120 from above the fiber web 110 to perform a shaping treatment. After blowing the first hot air W1, the female support member 130 was removed and the second hot air W2 was blown to perform a fusion treatment, thereby producing a nonwoven fabric.

The male support member 120 used was provided with a protrusion 121 having a sharp portion 124 at the upper end as shown in FIG. 10(A). The protrusion 121 has a prismatic shape with a height of 10 mm, and has a square shape of 2 mm x 2 mm when viewed from above. The pitch of the prisms was 5 mm in each of the MD and CD directions.

The female support member 130 is made of metal, and linear protrusions 131 each having a width of 2 mm are arranged at a pitch of 5 mm. The protrusions 131 of the female support member 130 were pushed between the protrusions 121 of the male support member 120. When the female support member 130 was pushed into the male support member 120, the space into which the fibers entered was 1 mm on each side.

The second blowing treatment with hot air was performed under conditions of a temperature of 160° C., a wind speed of 2 m/s, and a blowing time of 6 seconds. The obtained nonwoven fabric had a fineness of 1.8 dtex. The nonwoven fabric of Example 1 had ridges 12, a bottom 14 having openings 15, and a saddle 16 as shown in FIG.

[Example 2]
The female support member was changed to one having continuous protrusions in two orthogonal directions. The male support material was the same as in Example 1. Using core-sheath type (polyethylene terephthalate (PET)/polyethylene (PE) = 5:5) thermoplastic fibers with a fineness of 1.8 dtex, the nonwoven fabric of Example 2 was produced by a method including steps similar to those shown in FIG. Created. Thermoplastic fibers have been subjected to hydrophilic treatment. The second hot air blowing treatment was performed under conditions of a temperature of 160° C., a wind speed of 6 m/s, and a blowing time of 6 seconds.
The nonwoven fabric of Example 2 had ridges 12, a bottom 14 having openings 15, and a saddle 16.

[Comparative example 1]
A nonwoven fabric shown in FIG. 1 of JP-A No. 2013-133574 was produced using thermoplastic fibers with a fineness of 1.8 dtex according to the manufacturing method described in the same publication, and was used as a nonwoven fabric of Comparative Example 1. The nonwoven fabric of Comparative Example 1 had ridges and a bottom with openings, but did not have a saddle.

[Comparative example 2]
A nonwoven fabric of Comparative Example 2 was produced in the same manner as in Example 1, except that the male support member 120 did not have a sharp portion at the upper end of the protrusion. The nonwoven fabric of Comparative Example 2 had ridges, a bottom without openings, and a saddle.

[Comparative example 3]
A nonwoven fabric of Comparative Example 3 was produced in the same manner as in Example 2, except that the male support member 120 did not have a sharp portion at the upper end of the protrusion. The nonwoven fabric of Comparative Example 3 had ridges, a bottom without openings, and a saddle.

The structures of the nonwoven fabrics of Examples and Comparative Examples were investigated. Specifically, the basis weight, thickness, aperture size, angle of the wall region, fiber orientation of the wall region (orientation angle, orientation strength), and height difference between the ridge and saddle were determined using the following method. It was measured by

<Basic weight>
The area and mass of nonwoven fabrics stored for 24 hours or more in an environment of 23±2° C. and 50±5% relative humidity were determined.
<Thickness>
The thickness was measured using a thickness measuring device while applying a load of 0.05 kPa to the nonwoven fabric. As the thickness measuring device, a laser displacement meter manufactured by Omron Corporation was used. The thickness was measured at 10 points, and the average value thereof was calculated.

<Opening dimensions>
A microscopic photograph of the nonwoven fabric viewed from above was taken using the above-mentioned microscope, and the dimensions of the openings in the image were measured using the built-in measurement function.
<Angle of wall area>
A microscopic photograph of the II-II' cross section as shown in FIG. 4 was taken, and the angle θ was determined as explained with reference to FIG.

<Fiber orientation in wall region (orientation angle, orientation strength)>
A micrograph of the II-II' cross section as shown in FIG. 4 and a micrograph of the IV-IV' cross section as shown in FIG. The fiber orientation (orientation angle, orientation strength) was determined.
<Difference in height between ridge and saddle>
A micrograph of the IV-IV' cross section as shown in FIG. 7 was taken with the above-mentioned microscope, and measured using the built-in measurement function.

Furthermore, the effects of the nonwoven fabrics of Examples 1 and 2 and Comparative Examples 1 and 3 were investigated. Specifically, the liquid absorption time, liquid flow distance, and liquid return amount were measured for each nonwoven fabric. The measurement methods thereof are shown below.

<Absorption time>
The top sheet is removed from a commercially available baby diaper (trade name: "Merry's Sarasara Air Through M Size", manufactured by Kao Corporation, 2018), and in its place, a nonwoven fabric cut to 100 x 250 mm is laminated. A baby diaper for evaluation was produced by fixing the periphery of the laminated nonwoven fabric.

A load of 20 g/cm ² was applied evenly to the nonwoven fabric, and artificial urine was injected through a tube (cross-sectional area: 1000 mm ² ) placed approximately in the center of the nonwoven fabric. Physiological saline was used as artificial urine. 40 g of artificial urine was injected three times every 10 minutes, and the time (seconds) until the entire amount was absorbed was measured. When no artificial urine was found inside the cylinder, it was determined that the entire amount had been absorbed.

<Liquid flow distance>
The nonwoven fabric was cut into a size of 10 cm x 20 cm to prepare a sample for evaluation, and was fixed on a mounting section inclined at 45 degrees via commercially available tissue paper. 1 g of deionized water was injected over 10 seconds from a height of 10 mm above the evaluation sample, and the flow of deionized water was observed. The distance from the injection point on the perpendicular line to the point where deionized water was drawn into the evaluation sample was measured and defined as the liquid flow distance.
The shorter the liquid flow distance, the easier the liquid will penetrate inside. That is, the liquid drawing property is excellent.

<Liquid return amount>
120 g of physiological saline was injected into the nonwoven fabric placed horizontally, and the nonwoven fabric was allowed to stand for 10 minutes after the injection was completed. Filter paper No. manufactured by Advantech. An absorbent sheet (mass M1) prepared by stacking 20 sheets of 5C (100 mm x 100 mm) was placed on the nonwoven fabric sample. Furthermore, a weight adjusted to apply a pressure of 3.5 kPa centered on the saline injection point was placed. The mass of the filter paper after being placed for 1 minute was taken as M2, and (M2-M1) was taken as the liquid return amount. The smaller the liquid return amount, the better.
The obtained results are summarized in Table 1 below along with the structure of the nonwoven fabric.

As shown in Table 1, the nonwoven fabric of the example was provided with openings at the bottom, and the angle of the wall region was as large as 85° or more. Due to the large angle of the wall area, the nonwoven fabric of the example has a thickness of 6 mm. The fibers in the wall region have an orientation angle of 76° or more in the two measured directions and an orientation strength of 1.4 or more. Therefore, the nonwoven fabric of the example has a short absorption time of 170 seconds or less, a small liquid flow distance of 35 mm or less, and a small liquid return amount of 1.5 g or less.
By using the nonwoven fabric of the example as a topsheet, an absorbent article that can further shorten absorption time and liquid flow distance can be obtained.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

For example, in the above-described embodiment, the diaper 10 was used as an example of the absorbent article, but the absorbent article of the present invention is not limited to such diapers, but can also be used for sanitary napkins, panty liners, urine absorbing pads, etc. It is applicable to various absorbent articles.

1 Non-woven fabric 2 Top sheet 3 Back sheet 4 Absorbent core 10 Absorbent article 12 Ridge 12a Top region 12b Wall region 14 Bottom 15 Opening 16 Saddle 18 Hollow region

Claims (3)

An absorbent article comprising a liquid-permeable topsheet having a skin-contacting surface and an absorbent body disposed on the non-skin-contacting surface side of the topsheet,
The top sheet is made of a nonwoven fabric having a plurality of ridges arranged so as to protrude toward the skin contacting surface, and a bottom section provided between adjacent ridges,
A saddle connecting the adjacent ridges is provided to protrude from the bottom,
Each of the plurality of ridges includes a top and a wall that supports the top,
The wall portion extends substantially perpendicularly to the bottom portion,
The fibers of the wall portion are oriented substantially perpendicularly to the bottom portion,
The ridge portion and the saddle portion have a hollow region on the non-skin contact surface side,
An opening is formed in the bottom portion and extends from the skin-contacting surface side to the non-skin-contacting surface side ,
The bottom part has a larger amount of fibers fused together than the top part, and has a smaller amount of fibers than the top part.
Absorbent articles. The absorbent article according to claim 1, wherein the saddle portion has a height smaller than the ridge portion from the bottom portion. The absorbent article according to claim 1 or 2, wherein the orientation angle θ _ori of the fibers of the wall portion with respect to the bottom portion is 60° or more and 120° or less, and the orientation strength is 1.05 or more.

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