JP7130325B2 - absorbent article - Google Patents

Description

The present invention relates to absorbent articles.

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

A nonwoven fabric having an uneven structure on its surface has been proposed in order to enhance cushioning properties (for example, Patent Document 1). The concave-convex structure is formed by alternately arranging first protrusions and second protrusions that protrude in mutually opposite directions in different directions that intersect each other in plan view via the annular wall. In this nonwoven fabric, from the viewpoint of liquid drawing property, soft cushioning property, etc., the wall portion is substantially at any point in the plane direction defined by the first direction and the second direction. It has fiber orientation along the direction connecting with the second projecting portion.

JP 2012-136790 A

By imparting cushioning properties to the nonwoven fabric, the texture of the nonwoven fabric can be enhanced. Methods for imparting cushioning properties include increasing the amount of fibers (basis weight) to obtain thickness. However, there is a limit to increasing the amount of fibers from the viewpoint of softness and flexibility, and an excessive increase in the amount of fibers may rather impair the texture.

On the other hand, the nonwoven fabric having the concave-convex structure described in Patent Document 1 can have a thickness even if the amount of fibers is small, and the texture is improved as compared with the conventional flat nonwoven fabric. The nonwoven fabric described in Patent Document 1 has a soft cushioning property and good return when pressed, and also has a good liquid drawing property and an excellent excretion collecting property. It is described that it can be suitably used as a sheet or the like. Absorbent articles using such a nonwoven fabric as a surface sheet have room for further improvement in liquid drawing-in and liquid return.

TECHNICAL FIELD The present invention relates to an absorbent article that is excellent in liquid drawing property and capable of suppressing liquid return.

The present invention is an absorbent article comprising a liquid-permeable topsheet forming a skin-contacting surface and an absorbent body disposed on the non-skin-contacting side of the topsheet, wherein the topsheet is a plurality of ridges projecting from the skin-contacting surface and arranged in one direction and having hollow regions on the side of the non-skin-contacting surface; bottoms provided between adjacent ridges; and tops of the ridges. and a saddle provided on at least one of the bottoms, and a pair of walls supporting the tops of the ridges has a number of fibers per unit area equal to the tops and bottoms of the ridges. To a lesser extent, said bottom portion relates to an absorbent article having a hydrophobicity compared to said wall portions of said ridges.

ADVANTAGE OF THE INVENTION The absorbent article which concerns on this invention can suppress a liquid return while being excellent in the draw-in property of a liquid.

1 is a plan view showing the basic configuration of a disposable diaper as one embodiment of the absorbent article of the present invention; FIG. 2 is a cross-sectional view taken along line I-I' of FIG. 1; FIG. It is a partial perspective view which shows an example of a nonwoven fabric. 4 is a cross-sectional view taken along line II-II' of FIG. 3; FIG. 4 is a cross-sectional view taken along line III-III' of FIG. 3; FIG. 4 is a cross-sectional view taken along line IV-IV' of FIG. 3; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view schematically showing part of a preferred method for producing a nonwoven fabric used in the absorbent article of the present embodiment, in which (A) disposes a fibrous web on a male support material, FIG. 4B is an explanatory view showing the step of inserting the web into the male member of the support; ) is an explanatory view showing the step of removing the female support material and blowing the second hot air from above the formed fiber web to fuse the fibers. FIG. 4 is a plan view of a support male member; FIG. 4 is a plan view showing an example of a support female member; FIG. 4 is a plan view showing an example of a state in which a male support member and a female support member are combined; FIG. 10 is a plan view showing another example of a state in which the male support member and the female support member are combined;

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 side of the topsheet 2, An absorbent body 4 is arranged between the two sheets 2 and 3. The surface sheet 2 and the absorbent body 4 are integrated with an adhesive such as a hot-melt adhesive. The skin-contacting surface is the surface of the diaper 10 or its constituent members that faces the wearer's skin when worn, and the non-skin-contacting surface is the side opposite to the wearer's skin when worn. It is an aspect that is directed to The backsheet 3 can be formed using materials commonly used for backsheets of absorbent articles. For example, a liquid-permeable nonwoven fabric, such as a liquid-impermeable resin film, a water-repellent resin film, or a laminated sheet of a resin film and a nonwoven fabric, is used as the backsheet 3 in some cases.

The diaper 10 has a longitudinal direction Y that coincides with the front-rear direction of the wearer when worn, and a width direction X that intersects the longitudinal direction Y when the diaper 10 is spread flat as shown in FIG. have. In addition, the diaper 10 includes an abdominal portion A arranged on the abdomen of the wearer when worn, a dorsal portion B arranged on the dorsal side of the wearer when worn, and a portion between the abdominal portion A and the dorsal portion B. It has a crotch portion C in the longitudinal direction Y located therebetween. The diaper 10 is a spreadable disposable diaper, and has fastening tapes 7 on both side edges of the back portion B. As shown in FIG. The outer surface of the ventral portion A is provided with a landing zone 8 to which the fastening tape 7 is attached.

The absorbent body 4 in the diaper 10 comprises an absorbent core 4a and a core wrap sheet 4b wrapping it. The absorbent core 4a can be composed of, for example, a fiber stack of absorbent fibers such as pulp fibers, or a fiber stack of a mixture of absorbent fibers and water-absorbent polymers. Examples of 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 polyolefin, polyester, and polyamide, which are hydrophilized with a surfactant or the like, can also be used. As the core wrap sheet 4b, for example, tissue paper or water-permeable nonwoven fabric is used. The core wrap sheet 4b may wrap the entire absorbent core 4a with one sheet, or two or more sheets may be combined to wrap the absorbent core 4a.

Sheets 5 for forming three-dimensional gathers having elastic members 5a are arranged on both sides of the diaper 10 in the longitudinal direction Y. As shown in FIG. Due to the contraction of the elastic member 5a, three-dimensional gathers that stand up toward the wearer's skin are formed in the crotch portion C in the wearing state. In addition, leg elastic members 6 are arranged in a stretched state in portions arranged around the legs in the crotch portion C. As shown in FIG. By contraction of the leg elastic members 6, leg gathers are formed in the crotch part C in the wearing state to improve the fit around the wearer's legs.

The topsheet 2 of the diaper 10 of this embodiment is composed of a nonwoven fabric 1 having a strip-like uneven structure extending in one direction on the skin-contacting surface. The direction in which the concave-convex structure of the topsheet 2 extends coincides with the longitudinal direction Y of the diaper 10, but does not necessarily have to coincide. The uneven structure may extend in the width direction X of the diaper 10 .

A 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 by using thermoplastic resins such as polyethylene terephthalate (PET) and polyamide alone; structures such as core-sheath type and side-by-side type Composite fibers and the like. Examples of such conjugate fibers include fibers having a core-sheath structure in which the sheath component is PE or low melting point PP. Representative examples of core-sheath structure fibers include core-sheath structure fibers such as PET (core) and PE (sheath), PP (core) and PE (sheath), PP (core) and low melting point PP (sheath), etc. is mentioned.

The fibrous material preferably contains polyolefin fibers such as PE fibers, 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, PET (core) and PE (sheath), and PET (core) and low melting point PP (sheath) are mentioned. These fibers can be used alone or in combination of two or more to form a nonwoven fabric. In addition, the nonwoven fabric may contain fibers other than thermoplastic fibers.

The topsheet 2 of the diaper 10 of this embodiment is required to allow the excreted liquid to quickly permeate the absorbent body. In order to achieve this, it is preferable to subject the nonwoven fabric 1 constituting the surface sheet 2 to a hydrophilic treatment. By applying the hydrophilization treatment, the contact angle of the fibers of the nonwoven fabric 1 with water is reduced. The smaller the contact angle with water, the higher the hydrophilicity. The nonwoven fabric 1 can be hydrophilized by a known method. For example, a method of manufacturing the nonwoven fabric 1 by hydrophilizing the fibers of the nonwoven fabric 1 with a hydrophilic agent can be mentioned.

As the hydrophilic agent used for the hydrophilic treatment, various known agents can be used without particular limitation, and for example, a hydrophilic oil agent is used. Hydrophilic oils are generally anionic, cationic, amphoteric or nonionic surfactants, but are not particularly limited to these. These can also be used in the form of an aqueous solution or emulsion having a predetermined concentration. Preferred hydrophilic agents include aliphatic monocarboxylates, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl phosphates, glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, and fatty acid polyethylene glycols. , alkylamine salts, alkylbetaines, and the like.

An example of the nonwoven fabric 1 forming the surface sheet 2 will be described below with reference to FIGS. 3 to 6. FIG. In the nonwoven fabric 1 shown in FIG. 3, a plurality of ridges 12 adjacent to each other via the bottom 14 extend in one direction on the skin contact surface. A saddle portion 16 is provided on a part of the bottom portion 14 so as to connect adjacent ridge portions 12 . The saddle 16 is upwardly convex in a cross section along the direction in which the ridge 12 extends, and is downwardly convex in a cross section along a direction orthogonal to the extending direction of the ridge 12 . The ridges 12 need not be continuous in one direction and may be discontinuous. However, in this case as well, adjacent ridges 12 are connected by saddles 16 .

As shown in FIG. 4, the plurality of ridges 12 are arranged in one direction so as to protrude from the bottom 14 toward the skin contact surface. The nonwoven fabric 1 has a bottom portion 14 on the non-skin contact side. The ridges 12 have the same height along the continuously extending direction. In this specification, the height is “equivalent”, the height measured using a microscope VHX900 (manufactured by Keyence Corporation) is within the range of 0.9 times or more and 1.1 times or less of the measured average value refers to being

Each ridge 12 has a top (hereinafter referred to as "top region 12a") and a pair of walls (hereinafter referred to as "wall regions 12b") that support the top region 12a. Wall region 12b has portions where the fiber density is less than top region 12a and bottom region 14 . Also, the top region 12a has a portion where the fiber density is greater than that of the bottom region 14 . Since the fiber density of the wall region 12b is smaller than others, the nonwoven fabric 1 as a whole has improved breathability and liquid permeability. Liquid in contact with the skin-contacting surface can easily permeate inside through the wall region 12b. Fiber density herein refers to the number of fibers per unit area in the cross section of the nonwoven fabric. In this specification, "a certain area has a lower fiber density than other areas (the number of fibers per unit area is small)" means that a part of a certain area has a lower fiber density than a part of another area. This also means that there is a portion with a small number of fibers per unit area. That is, with respect to the wall region 12b, the top region 12a and the bottom 14, it is preferable that the total number of fibers per unit area of the wall region 12b is smaller than that of the top region 12a and the bottom 14; Without limitation, a configuration may be included in which only a portion of wall region 12b has fewer fibers per unit area than top region 12a and bottom region 14. FIG.

An angle θ between the bottom portion 14 and the wall region 12b (the inclination angle of the wall region 12b) is 60° or more and 120° or less, preferably 70° or more, and more preferably 80° or more. , and is preferably 110° or less, more preferably 100° or less. The smaller the inclination angle θ, that is, the closer the wall is to a plane perpendicular to the plane, the greater the distance from the bottom 14 to the top region 12a, and the higher the ridges 12 are formed. Become.

The angle θ between the bottom portion 14 and the wall region 12b may partially fall outside the above range. For example, the wall region 12b may have a wavy shape. The inclination angle θ is determined, for example, using a microscope VHX900 (manufactured by Keyence Corporation), in a cross section including the top region 12a, the wall region 12b, and the bottom 14 (for example, FIG. 4). It can be confirmed by measuring the angle formed by

Note that the tilt angle θ may be measured by other measuring methods. For example, the nonwoven fabric 1 is installed so that the bottom portion 14 abuts on the surface of a horizontal table, and in a cross section (for example, FIG. 4) including the top portion region 12a, the wall portion region 12b, and the bottom portion 14, the wall portion region 12b and the horizontal table It is also possible to obtain the inclination angle θ by measuring the angle formed by . The wall region 12b may be flat, uneven instead of flat, or perforated. When the wall region 12b is not flat or has holes, a virtual plane is set from the intersection of the bottom 14 and the wall region 12b to the intersection of the top region 12a and the wall region 12b. and the angle formed by the bottom portion 14 can be measured as the inclination angle θ.

Furthermore, the lower fiber density of the wall region 12b makes it easier for the ridges 12 to follow the movements of the wearer's skin when the diaper 10 is in use. By this, it is possible to achieve a good feeling on the skin. The nonwoven fabric 1 having regions with different fiber densities in this manner can be produced, for example, by a method described later.

The fiber density can be measured by observing the cross section of the nonwoven fabric 1 and using the following method. The nonwoven fabric 1 is cut in the thickness direction so as to pass through the site to be measured (for example, between the wall regions 12b). A scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.) is used to observe the cut surface under magnification, and the cross-sections of cut fibers within a certain area of the cut surface are counted. Magnification observation is adjusted to a magnification (150 times or more and 500 times or less) at which about 30 to 60 fiber cross sections can be measured. Next, the number of fiber cross sections per 1 mm ² is converted into the fiber density (fibers/mm ² ). The fiber density of the sample is obtained by averaging the three measurements.

The nonwoven fabric 1 has hollow regions 18 on the non-skin-contacting side of the ridges 12 . As used herein, the term "hollow region" refers to a space that is substantially unfilled with fibers of the nonwoven fabric, specifically having a fiber density of less than 20 fibers/mm ² as described above. It is preferable that the fiber density in the hollow region 18 is as small as possible. The hollow regions 18 are continuous in the direction in which the ridges 12 of the nonwoven fabric 1 extend, and act as ventilation paths. Hollow region 18 facilitates liquid transfer to absorbent 4 in diaper 10 . By having the hollow region 18, the nonwoven fabric 1 has an enhanced cushioning property and has a structure that is difficult to collapse in the thickness direction.

The bottom 14 is more hydrophobic than the wall region 12b. As used herein, "a region is more hydrophobic than other regions" means that a portion of a region is more hydrophobic than a portion of another region. That is, with respect to the bottom portion 14 and the wall portion region 12b, it is preferable that the entire bottom portion 14 has hydrophobicity compared to the wall portion region 12b, but it is not limited to this. A configuration having a hydrophobicity relative to the wall region 12b may also be included. The degree of hydrophobicity can be evaluated based on the contact angle with water measured by the method described below. A larger contact angle indicates greater hydrophobicity. In the following description, "highly hydrophobic" means having more hydrophobicity than the standard, and "less hydrophobic" means less hydrophobic than the standard. It means that you do not have In these cases, the difference between the water contact angle of the reference and the water contact angle of the object to be measured (the difference in the water contact angle with respect to the reference) is preferably 7° or more, and is 8° or more. is more preferable.

Deionized water is used for the measurement of the contact angle, with the fiber taken out from the bottom portion 14 or the wall portion region 12b as a measurement sample. As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. The amount of liquid ejected from an ink-jet type water droplet ejector (a pulse injector CTC-25 with an ejection port hole diameter of 25 μm, manufactured by Cluster Technology) is set to 20 picoliters, and water droplets are dropped just above the measurement sample. The drip is recorded on a high-speed video recorder connected to a horizontally mounted camera. From the viewpoint of image analysis later, the recording device is preferably a personal computer with a built-in high-speed capture device.

In this measurement, an image is recorded every 17 msec. In the recorded video, the first image of water droplets landing on the measurement sample was captured using the attached software FAMAS (software version: 2.6.2, analysis method: droplet method, analysis method: θ/2 method, image The processing algorithm is non-reflection, the image processing image mode is frame, the threshold level is 200, and the curvature correction is not performed). Calculate the contact angle.

A sample for measurement is cut into a fiber length of 1 mm, the fiber is placed horizontally on a sample table of a contact angle meter, and the contact angle is measured at two different positions for each fiber. At each part, N = 5 contact angles are measured to one decimal place, and the average value of the total 10 measured values (rounded to the second decimal place) is defined as the contact angle at each part. do. The measurement is carried out in an environment of room temperature (20° C.) and humidity of 60%, and the deionized water and measurement sample to be used are stored in the environment for one day or more before use.

Since the bottom 14 is more hydrophobic than the wall region 12b, liquid that contacts the skin-contacting surface is easily directed to the wall region 12b. Since the fiber density of the wall region 12b is low, the liquid can quickly permeate the interior from the wall region 12b and move from the hollow region 18 to the absorbent body 4 in the lower layer. Moreover, since the bottom portion 14 is highly hydrophobic, there is little possibility that the liquid that has penetrated inside will return to the outside via the bottom portion 14 . If the bottom portion 14 is more hydrophobic than the wall region 12b over the entire surface, the effect is further enhanced. In addition, when the central portion of the bottom portion 14 has a higher fiber density than the vicinity of the wall region 12b, the hydrophobic agent tends to gather in the central portion of the bottom portion 14. Therefore, the hydrophobicity of the bottom portion 14 increases from the central portion The gradation becomes gradually smaller toward the vicinity of the wall region 12b, and the liquid drawing effect and the liquid return suppressing effect are further enhanced.

3, the ridges 12 and the saddles 16 are alternately arranged as shown in FIG. The saddle portion 16 is convex downward in the direction connecting the adjacent ridge portions 12 . On the other hand, FIG. 6 shows that the saddle 16 is upwardly convex in the IV-IV' line cross section in FIG. That is, the saddle portion 16 is a region having a shape curved in opposite directions in two intersecting directions in the thickness direction of the nonwoven fabric 1 .

In a cross-section where the saddle 16 is downwardly convex (eg FIG. 5), the curvature of the saddle 16 depends on the distance d between adjacent top regions 12a. The smaller the distance d between adjacent apex 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 microscope described above. The radius of curvature of the edge of the saddle portion 16 can be obtained, for example, by imagining a virtual surface on the edge of the saddle portion 16 from the side of the skin-contacting surface and measuring the radius of a circle in contact with the virtual surface.

The radius of curvature of the saddle portion 16 can also be obtained for a cross section (for example, FIG. 6) in which the saddle portion 16 is convex upward. In this case, the radius of curvature of the edge of the saddle portion 16 can be obtained by assuming a virtual surface on the edge of the saddle portion from the non-skin-contacting side and measuring the radius of a circle in contact with the virtual surface.

The thickness direction distance from the bottom portion 14 to the saddle portion 16 is about 0.01 to 100 times the thickness direction distance from the top region 12 a to the saddle portion 16 . The distance in the thickness direction from the bottom portion 14 to the saddle portion 16 is determined, for example, by setting the nonwoven fabric 1 so that the bottom portion 14 is in contact with the surface of a horizontal table and making the saddle portion 16 convex upward in a cross section (for example, FIG. 6). can be obtained by measuring the height from the base to the saddle 16. The nonwoven fabric 1 is placed so that the bottom portion 14 abuts on the surface of a horizontal table, and the height from the horizontal table to the saddle portion 16 is measured in a section where the saddle portion 16 is downwardly convex (for example, FIG. 5). The distance in the thickness direction from 14 to saddle 16 may be determined.

The distance in the thickness direction from the top region 12a to the saddle portion 16 can be obtained as follows. That is, in a section (for example, FIG. 5) where the nonwoven fabric 1 is placed so that the bottom portion 14 is in contact with the surface of a horizontal table, and the saddle portion 16 is downwardly convex (for example, FIG. 5), the height from the horizontal table to the top region 12a Measure the height to The difference between the height from the horizontal platform to the top region 12a and the height to the saddle 16 thus obtained corresponds to the distance from the top region 12a to the saddle 16 in the thickness direction. The microscope described above 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, which will be described later.

A saddle 16 having such a shape does not necessarily connect adjacent ridges 12 at the bottom 14 . A saddle 16 may be provided on the bottom 14 at a distance from the ridge 12 . Alternatively, it can be provided in the top region 12 a of the ridge 12 . In either case, the presence of the saddle portion 16 having a predetermined shape on the skin-contacting surface of the nonwoven fabric 1 imparts resistance to pressure in the thickness direction to the nonwoven fabric 1, making the nonwoven fabric 1 less likely to collapse. Furthermore, the effect of inducing the flow of liquid on the surface of the nonwoven fabric 1 can be obtained.

In the illustrated example, the saddles 16 are provided so as to connect adjacent ridges 12 . Since the saddles 16 connect the adjacent ridges 12, the load applied to the ridges 12 is not biased. As a result, deformation of the ridges 12 in the X direction is suppressed, making it easier to maintain the height of the ridges 12 . In addition, since the saddle 16 connects the ridges 12, the load applied to the nonwoven fabric 1 can be dispersed within the skin contact surface. Since the nonwoven fabric 1 has good elasticity and cushioning properties, the texture is improved.

The saddle 16 has a hollow region 18' on the non-skin contact side as shown in FIG. The hollow region 18' is a region having a fiber density of less than 20 fibers/mm ² as described above. Hollow regions 18 ′ of the saddle portion 16 and hollow regions 18 of the ridges 12 on the non-skin-contacting side form concave portions in the longitudinal and lateral directions on the non-skin-contacting side of the nonwoven fabric 1 . As a result, in the diaper 10 , a communicating space is formed between the nonwoven fabric 1 and the absorbent body 4 . The presence of the hollow regions 18 ′ in addition to the hollow regions 18 further enhances the cushioning properties of the nonwoven fabric 1 and provides a structure that is more resistant to crushing in the thickness direction. In addition, since the communicating space between the nonwoven fabric 1 and the absorbent body 4 also functions as a channel for the collected liquid, the ability to draw the liquid into the absorbent body 4 is improved. Moreover, holding the liquid in the communication space also contributes to suppression of liquid return to the surface. In addition, since the position of the saddle portion 16 is not limited as described above, the hollow area may not be formed on the non-skin-contacting surface side. Even in this case, the effect of the hollow region 18 existing on the non-skin-contacting side of the ridge 12 is exhibited without any loss.

Since the diaper 10 of the present embodiment includes the nonwoven fabric 1 as described above as the surface sheet 2, the liquid easily permeates from the skin-contacting side to the inside during use, and the liquid drawability is excellent. . Even if the permeated liquid returns toward the skin-contacting surface, it is less likely to flow out from the skin-contacting surface.

The bottom portion 14 of the nonwoven fabric 1 does not necessarily have to be entirely flat, and a portion thereof may be curved toward the skin contact surface. This facilitates the flow of liquid to the wall region 12b of the ridge 12. FIG. The non-woven fabric 1 is even more difficult to collapse by forming the convex portions, which are partially curved toward the skin-contacting surface side, on the bottom portion 14 between the adjacent ridges 12 as well. Liquid flow to the outside through the bottom 14 is more reliably blocked. The convex portion formed on the bottom portion 14 may extend in any direction.

The fibers contained in the nonwoven fabric 1 are oriented in a predetermined direction in each of the top region 12a, the wall region 12b, and the bottom portion 14. As shown in FIG. The orientation direction of the fibers in the wall region 12b is different from the top region 12a and the bottom region 14. FIG. Specifically, in top region 12a and bottom 14, the fibers are oriented in the planar direction, and in wall region 12b, the fibers are oriented in the thickness direction. Since the fibers are oriented in the thickness direction in the wall region 12b, the ridges 12 are not easily deformed in the height direction and can maintain their shape even when subjected to a pressing force. Since the hollow region 18 is maintained, liquid return can be suppressed more reliably. The nonwoven fabric 1 having such saddle portions 16 can be produced, for example, by a method described later.

"The fibers are oriented in the planar direction" means that the degree of orientation of the fibers obtained by the measurement method described below is less than 45%. When the degree of orientation of the fibers is less than 45%, more than half of the fibers are aligned in the planar direction, and the flat shape can be maintained. The fibers oriented in the thickness direction contribute to maintaining the shape and strength of the nonwoven fabric 1, so they may be included in the top region 12a. In this case, the orientation degree of the fibers can be 30% or more and less than 40%. It is preferably 38% or less, more preferably 37% or less.

The wall region 12b is a portion where 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 degree of orientation of the fibers obtained by the measurement method described later is 60% or more. When the degree of orientation of the fibers in the wall region 12b is 60% or more, it can be said that the fibers are arranged perpendicular to the plane in the thickness direction of the nonwoven fabric 1 .

The wall region 12b has a fiber orientation of 60% or more, and some of the fibers are fused together. As a result, the wall region 12b stands up in a column-like state, and appropriate elasticity can be imparted to the nonwoven fabric 1 in the thickness direction. In addition, since such a region does not exist in the fibers of conventional non-woven fabrics, the fibers follow the deformation when pressed in the thickness direction. Conventional nonwoven fabrics are deformed so as to fill spaces between fibers when pressed, and the amount of deformation increases as the applied stress increases.

The degree of orientation of the fibers in the wall region 12b is preferably 63% or more, more preferably 65% or more, and even more preferably 68% or more, from the viewpoint of cushioning properties. The degree of orientation also influences the percentage of fusion points that result in stress-bearing structures. The degree of fiber orientation in the wall region 12b is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less.

In order to determine the degree of orientation of the fibers, first, a 5 mm × 5 mm section is cut from the nonwoven fabric 1, and a section having a II-II' cross section as shown in FIG. 4 and a IV-IV' cross section as shown in FIG. Make a section with The degree of orientation can be determined by observing the cross section at each section.

Each section is placed on a flat support and a load of 2.9 Pa is applied to observe the cross section. Specifically, the section is placed on a base of a digital microscope (VHX-900) manufactured by Keyence Corporation. A black cardboard with a basis weight of 300 g/m ² is placed on the section, and the section is observed at a magnification of 20 using a VHX220R lens manufactured by Keyence Corporation. Thus, the boundaries in the cross section can be determined.

Based on the determined boundaries, portions of the top region 12a, the wall region 12b, and the bottom 14 for which the degree of fiber orientation is to be determined are defined. For each site, the number of fibers in a given area is measured. The number of fibers crossing the reference line orthogonal to the thickness direction of the nonwoven fabric is defined as "the number of longitudinal fibers", and the number of fibers crossing the reference line orthogonal to the thickness direction of the nonwoven fabric is defined as the "number of horizontal fibers". Using this, the degree of orientation is calculated by the following formula.

Degree of orientation = (number of vertical fibers) / (number of vertical fibers + number of horizontal fibers) x 100
The top region 12a, the wall region 12b, and the bottom region 14 are each measured at four points, and the average value is taken as the degree of orientation at each point.

The nonwoven fabric 1 preferably has a portion at the bottom 14 that is more hydrophobic than the top region 12a. In this case, the wall region 12b and the top region 12a are relatively hydrophilic. The hydrophilicity of the top region 12a can reduce backflow and allow rapid liquid permeation. The fibers on the skin-contacting side of the top region 12a preferably have a water contact angle of 74° or more, more preferably 76° or more. The upper limit is preferably 80° or less.

The nonwoven fabric 1 preferably has a portion in the top region 12a that is more hydrophobic than the wall region 12b. Since the hydrophilicity of the top region 12a is lower than that of the wall region 12b, it becomes difficult for the liquid that has penetrated inside to pass through the top region 12a.

In the ridge 12, it is preferable that at least the non-skin-contacting surface 12c of the top region 12a has a portion that is more hydrophobic than the wall region 12b (see FIG. 4). Liquid flow to the outside through the top regions 12a of the ridges 12 is more reliably prevented. The surface of the top region 12a is desired to be more hydrophilic than the wall region 12b so as not to impair the feel.

The bottom 14 may vary in hydrophobicity towards the wall region 12b. When the hydrophobicity increases toward the wall region 12b, the permeation of the liquid to the inside is further promoted, and the flow of the returned liquid to the outside can be more reliably prevented.

A preferred embodiment of the method for manufacturing the nonwoven fabric 1 will be described below with reference to FIGS.
In manufacturing the nonwoven fabric 1 of the present embodiment, first, as shown in FIG. impose. As shown in FIG. 8, the support male member 120 has projections 121 spaced apart in one direction and in a direction orthogonal thereto. On the other hand, as shown in FIG. 9, the support female member 130 is provided with a projection 131 continuous in one direction.

The support male member 120 has a plurality of protrusions 121 corresponding to positions where the bottom portion 14 surrounded by the ridges 12 and the saddle portions 16 of the nonwoven fabric 1 is formed. A recess 122 corresponding to the position where the ridge 12 is formed is formed between adjacent protrusions 121 . As a result, the support male member 120 has an uneven shape, and the protrusions 121 and the recesses 122 are alternately arranged in different directions in plan view. A base portion 123 of the concave portion 122 has a structure through which hot air can pass. For example, a plurality of through holes (not shown) are provided.

In this embodiment, the support for producing the nonwoven fabric 1 has a machine direction (MD direction) corresponding to the Y direction of the nonwoven fabric 1 and a width direction (CD direction) orthogonal to the machine 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 support male member 120 is 3 mm or more, the nonwoven fabric 1 with a cushioning feel can be manufactured. 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 prismatic or cylindrical. In the illustrated example, in plan view, the nonwoven fabric 1 has a quadrangular shape in the MD direction, but it may also have a rhombic shape. The protrusion 121 is preferably a prism and is square in plan view. In this case, the fibers enter the support male member 120, the shape of the nonwoven fabric 1 is maintained, and the thickness of the nonwoven fabric 1 can be easily secured.

Considering how easily the shape of the nonwoven fabric 1 can be maintained, the area of the upper surface of one projection 121 in plan view is preferably 3 mm ² or more. Also, the distance between adjacent projections 121 is preferably 2 mm or more in a plan view. In this case, a space for effectively pushing the fibers can be secured.

The female support member 130 has a projection 131 that corresponds to the recess 122 of the male support member 120 and continues in one direction in plan view. A recess 132 corresponding to the protrusion 121 of the support male member 120 is formed between adjacent protrusions 131 . As a result, the support female member 130 has an uneven shape, and the protrusions 131 and the recesses 132 are alternately arranged. A base portion 133 of the concave portion 132 allows hot air to pass through, and is provided with, for example, a plurality of through holes.

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 spacing 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 shaped appropriately. are 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 . Therefore, it is preferable that the protrusion 131 has a length of 1 mm or more.

The pitch of the projections 131 is set so that the projections 121 on the male support member 120 and the recesses 132 on the female support member 130 are fitted to form the nonwoven fabric 1 continuous in the planar direction. Specifically, the pitch of the protrusions 131 is preferably longer than the length of one side of the protrusions 121 of the support male member 120 in plan view by 1 mm or more. When the shape of the top surface of the protrusion 121 is circular or oval, the length of one side of the top surface of the protrusion 121 is the length of the diameter or major axis.

A fiber web 110 shown in FIG. 7(A) is supplied from a carding machine (not shown) to a position for shaping the web. The fibrous web contains hydrophilically treated thermoplastic fibers. The support female member 130 is pushed in from above the fiber web 110 as shown in FIG. 7(B). At this time, the protrusion 121 of the support male member 120 and the recess 132 of the support female member 130 are fitted, and the recess 122 of the support male member 120 and the protrusion 131 of the support female member 130 are fitted. The support male member 120 and the support female member 130 are combined as shown in FIG. In FIG. 10, the fiber web is omitted.

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

As shown in FIG. 7B, fibers are oriented in the thickness direction in a region 112b sandwiched between the side surface of the protrusion 121 of the male support member 120 and the side surface of the protrusion 131 of the female support member 130. As shown in FIG. On the other hand, in the region 112a between the recess 122 of the male support member 120 and the end surface of the projection 131 of the female support member 130, the fibers are oriented in the planar direction. Since the female support member 130 is pressed, the fibers oriented in the planar direction in the region 112a are denser than in the other region 112b.

As shown in FIG. 10, the protrusions 131 of the female support member 130 do not enter into the recesses 122 between the adjacent protrusions 121 of the male support member 120 in portions 122a corresponding to the recesses 132 of the female support member 130. . Therefore, in the fiber web (not shown), the fibers are pulled in a region 122a surrounded by the projections 121 of the male support member 120 and the projections 131 of the female support member . In this way, regions with different fiber orientations are formed to form 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 female support member 130 side as shown in FIG. 7(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 show the flow of the first hot air W1.

In a region 112b between the wall surface of the protrusion 121 of the support male member 120 and the wall surface of the protrusion 131 of the support member 130, a wall region 12b in which fibers are oriented in the thickness direction is formed. In the area 114 between the end face of the protrusion 121 and the base of the recess 132, the fibers are fused by receiving the first hot air W1 to such an extent that the shape can be maintained in the planar direction. Thereby, a fiber layer corresponding to the bottom portion 14 is formed. In the area 112a between the base 123 of the recess 122 and the end face of the protrusion 131, the fibers are oriented in the planar direction. Since the protrusions 131 separate the hot air, the formed fiber layer is smooth with less fiber fusion. Thereby, a fiber layer corresponding to the top region 12a is formed.

The temperature of the first hot air W1 is set to a temperature higher than the melting point so that the thermoplastic fibers can retain their shape in the thickness direction and plane direction. Considering common 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 is 5°C or more and 50°C or less. It is more preferable to have

From the viewpoint of effective fusion, the speed of the first hot air W1 is preferably 2 m/s or more, more preferably 3 m/s or more. Moreover, 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 device scale compact. In this way, the fiber web 110 is heat-sealed and held in an uneven shape.

Next, the female support member 130 is removed, and a second hot air W2 is blown to further fuse the fibers of the fiber web 110 having the uneven shape so that the fibers can be appropriately fused. As shown in FIG. 7(C), similarly to the first hot air W1, it is preferable to blow the second hot air W2 onto the fiber web 110 from the non-skin-contacting side of the nonwoven fabric 1 . The temperature of the second hot air W2 is set to a temperature higher than the melting point so that the thermoplastic fibers can retain their shape in the thickness direction and 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 5°C or more and 50°C or less. It is more preferable to have

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 depends on the height of the projections 121 of the support male member 120 . As a result, heat transfer to the fibers is sufficient, and the fibers are fused to each other, so that 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. As a result, excessive heat transfer to the fibers is suppressed, and the nonwoven fabric 1 with good texture can be obtained.

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, it is possible to remove the female support member in the step of blowing the second hot air W2 without causing unfused fibers to cling to it. In other words, after the web is produced, the male support member and the female support member are fitted together, the female support member is removed as it is, and the web can be treated with the second hot air W2. This makes the 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, a composite fiber made of a plurality of resin components, or the like. Composite fibers include, for example, 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 (for example, a core-sheath composite fiber having a low melting point component in the sheath and a high melting point component in the core) as the thermoplastic fiber, the temperature of the hot air blown onto the fiber web 110 is the low melting point. It is preferably above the melting point of the component and below the melting point of the high-melting component. More preferably, the temperature is at least the melting point of the low-melting component and 10°C lower than the melting point of the high-melting component, and more preferably at least 5°C above the melting point of the low-melting component and at least 20°C lower than the melting point of the high-melting component. . Moreover, from the viewpoint of elasticity, the more the core having a high melting point among the core-sheath composite fibers, the higher the elasticity. Therefore, it is preferable that the core component has a large cross-sectional area ratio.

The nonwoven fabric 1 is produced as described above. On the side surface of the projection 121 of the support male member 120, the fibers of the fiber web 110 are aligned and oriented in the thickness direction to form the wall region 12b. A bottom portion 14 in which fibers are oriented in the plane direction is formed on the top portion of the protrusion 121 . A saddle portion 16 is formed on a portion of the bottom portion 14 . A base portion 123 of the concave portion 122 is formed with a top region 12a in which fibers are oriented in the planar direction.

In this embodiment, the obtained nonwoven fabric 1 is incorporated into the diaper 10 so that the lower surface in FIG. 7C is a skin contact surface and the opposite surface is a non-skin contact surface. is That is, the non-skin-contacting surface of the nonwoven fabric 1 is the side on which the male support member 120 is arranged, and the non-skin-contacting surface is the side to which the first hot air W1 and the second hot air W2 are blown. Therefore, due to the difference in the blowing amount of the first hot air W1, the amount of fusion bonding between the fibers of the bottom portion 14 of the non-skin contacting surface is greater than that of the top region 12a of the skin contacting surface. However, on the contrary, the nonwoven fabric 1 may be incorporated into the diaper 10 such that the lower surface of the nonwoven fabric 1 in FIG.

Furthermore, due to the small amount of heat, the surface of the top region 12a on the side of the skin contacting surface is smoother and more pleasant to the touch than the surface of the bottom portion 14 on the side of the non-skin contacting surface. 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.

Further, 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 side of the nonwoven fabric 1 ) are pulled toward the male support member 120 . Therefore, the amount of fiber in the bottom portion 14 on the side of the non-skin contacting surface formed on the top of the projection 121 of the male support member 120 is the same as that on the side of the skin contacting surface formed on the base portion 123 of the recess 122 of the male support member 120. is less than the top region 12a of the .

In the nonwoven fabric manufacturing method of the present embodiment, the thickness of the nonwoven fabric 1 is appropriately determined by the heights of the protrusions 121 of the support male member 120 and the protrusions 131 of the support female member 130 . For example, increasing the height of the protrusions increases the apparent thickness of the sheet, and decreasing the height of the protrusions decreases the apparent thickness of the sheet. In addition, if the height of the projections is increased, the fiber density of the nonwoven fabric 1 will be low, and if it is decreased, the fiber density of the nonwoven fabric 1 will be increased.

In the manufacturing method described above, the female support member 130 having a plurality of projections 131 continuous in one direction was used, but for example, as shown in FIG. It is also possible to change the support female member 130A to have a In the support female member 130A used here, a plurality of concave portions 132 arranged in a grid pattern in a plan view are formed by crossing the protrusions 131A and 131B that are continuous in two orthogonal directions. That is, the concave portion 132 is a rectangular region surrounded by a projection 131A continuously extending in one direction and a projection 131B continuously extending in a direction perpendicular to the projection 131A. It is formed so as to penetrate through the The recess 132 is formed corresponding to the protrusion 121 of the support male member 120 so as to receive the protrusion 121 . Even when the female support member 130A is changed to such a support member 130A, the same male support member 120 can be used to manufacture a nonwoven fabric according to the method described with reference to FIG.

As shown in FIG. 7B, by pushing the female support member 130A into the fiber web 110 on the male support member 120, each projection 121 of the male support member 120 fits into each concave portion 132 of the female support member 130A. The projections 131A and 131B of the female support member 130A are inserted into the recesses 122 of the male support member 120 while being inserted. A plan view of this state is schematically shown in FIG. In FIG. 11, the fiber web is omitted. A fiber web (not shown) is sandwiched between the four wall surfaces of the projections 121 of the male support member 120 and the wall surfaces of the recesses 132 of the female support member 130A surrounding them. As a result, the fibers of the fiber web 110 are oriented in the thickness direction.

In the female support member 130A used here, only the projections 131A extending in one direction press the fiber web at the end surface against the base portion 123 of the concave portion 122 of the male support member 120 as shown in FIG. A fibrous layer corresponding to is formed. In the other direction, the fiber web pressed in the recess 122 a of the male support member 120 by the end face of the protrusion 131 B does not reach the base 123 of the recess 122 of the male support member 120 . This area of the fibrous web becomes the fibrous layer corresponding to the saddle 16 .

When the second hot air W2 is blown in the step shown in FIG. A web (not shown) may be placed. In this case, it is possible to obtain a nonwoven fabric having a two-layer structure in which a second nonwoven fabric layer is further provided on the non-skin-contacting side.

The nonwoven fabric 1 can be suitably used, for example, as a surface sheet of absorbent articles such as disposable diapers for adults and infants, sanitary napkins, panty liners, and incontinence pads. When used as a topsheet, either side may face the wearer's skin. Considering the orientation direction of the fibers, it is more preferable to use the ridges 12 with the top region 12a side facing the wearer's skin.

For example, when the nonwoven fabric 1 is used as the topsheet 2 of the diaper 10 shown in FIG. 1, the nonwoven fabric 1 can be integrated with the absorbent body 4 using a hot-melt adhesive. Examples of hot-melt adhesives include styrene-isobutylene-styrene (SIS) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, styrene-ethylene-butylene-styrene (SEBS) copolymers, and the like. block copolymer-based hot-melt adhesives.

Hot melt adhesives can be applied by any method. Examples of coating methods include curtain spray, spiral spray, slot coating, die coating, pattern coating, beat coating and dot coating. The method of attaching the nonwoven fabric 1 and the absorbent body 4 is not particularly limited. For example, a method of bonding the nonwoven fabric 1 to the absorbent body 4 coated with the hot-melt adhesive may be used, or a method of bonding the absorbent body 4 to the nonwoven fabric 1 coated with the hot-melt adhesive. Alternatively, a hot-melt adhesive may be applied to both the absorbent body 4 and the nonwoven fabric 1, and then the two may be pasted together. A hot-melt adhesive can also be applied at the same time as the absorbent body 4 and the nonwoven fabric 1 are attached.

By using a hydrophobic hot-melt adhesive, the nonwoven fabric 1 integrated with the absorbent body 4 has a greater hydrophobicity in the bottom 14 than in the wall region 12b. When the nonwoven fabric 1 is attached to the absorbent body 4 coated with the hot-melt adhesive, only the bottom portion 14 is made hydrophobic. On the other hand, when the absorbent body 4 is attached to the nonwoven fabric 1 coated with the hot-melt adhesive, the hydrophobic hot-melt adhesive permeates the bottom 14 and the entire bottom 14 becomes hydrophobic. Either case is desirable from the viewpoint of improving the performance.

In addition to the method of imparting hydrophobicity to the bottom portion 14 with a hydrophobic hot-melt adhesive, the bottom portion 14 of the nonwoven fabric 1 may be subjected to a hydrophobic treatment before being integrated with the absorbent body 4 . For example, a method of spraying a hydrophobic agent from the non-skin-contacting side of the nonwoven fabric 1 can be used. Alternatively, a hydrophobic oil agent may be applied from the non-skin-contacting side of the nonwoven fabric 1 with a brush or the like. Alternatively, a hydrophobizing agent can be applied to the bottom portion 14 by any printing method such as flexographic printing, inkjet printing, gravure printing, screen printing, etc. from the non-skin-contacting side to perform hydrophobizing treatment.

In addition, from the non-skin contact side, a hydrophobic agent is attached to the bottom 14 by a technique such as curtain spray, spiral spray, slot coating, die coating, pattern coating, beat coating, dot coating, kiss coating, touch roll coating, etc. A hardening treatment can also be applied. By applying the hydrophobic treatment from the non-skin-contacting surface side in this manner, the hydrophobicity of the bottom portion 14 can be made greater than that of the wall portion region 12b by a simple technique. In this case, the non-skin-contacting surface 12c of the ridge 12 is also made hydrophobic because the hydrophobic treatment is performed from the non-skin-contacting surface.

As the hydrophobic agent, hydrophobic monomers, oligomers, polymers, and resins can be used singly or in combination of two or more. Hydrophobic agents include, for example, acid chloride type water repellents, isocyanate type water repellents, ketene dimer type water repellents, pyridine condensation type water repellents, ethylene urea type water repellents, methylol compound type water repellents, and ethylene oxide type water repellents. Water repellent agents, silicon compound water repellent agents, chromium complex compound water repellent agents, titanium-containing compound water repellent agents, zirconium-containing compound water repellent agents, fluorine compound water repellent agents, silicon compound water repellent agents, etc. mentioned.

Other water repellents include oils (vegetable oils, animal oils, vegetable fats, animal fats), higher aliphatic compounds (saturated or unsaturated acids, alcohols, esters, amines, amides, salts), waxes (vegetable waxes, animal waxes, mineral waxes, petroleum waxes, modified waxes) and the like. Modified products thereof and mixtures thereof may also be used. Silicon compound-type water repellents are typically chain polydimethylsilicone, and include modified silicone in which a portion of the methyl group is replaced with polyether, phenyl group, or trifluoropropyl group.

As the fluorine compound type water repellent, polymers of acrylic acid esters of alcohols containing perfluoroalkyl groups, phosphoric acid esters, and the like are used. Silicon compound-type water repellents are excellent in flexibility as well as in hydrophobicity, and are suitable for treating surface agents that come into direct contact with the skin. Fluorine compound type water repellents exhibit the most excellent hydrophobicity, and are particularly advantageous in that they can maintain their hydrophobicity even when in contact with surfactants for hydrophilization.

Alternatively, hydrophilic agents can be removed from the fibers contained in bottom 14 to make bottom 14 more hydrophobic. For example, the bottom 14 can be soaked in any solvent to remove the hydrophilic agent from the fibers contained in the bottom 14 . Alternatively, the hydrophilic agent may be removed from the fibers contained in the bottom portion 14 by bringing the bottom portion 14 into contact with a kiss roll, touch roll, or the like to which any solvent is adhered. The solvent is not particularly limited, and any solvent can be used. For example, water or alcohols can be used.

In order to increase the hydrophobicity of the bottom portion 14 , hydrophobic fibers may be arranged in the portion corresponding to the bottom portion 14 in the fiber web 110 for manufacturing the nonwoven fabric 1 . For example, by arranging the hydrophobic fibers at positions where the ends of the projections 121 of the support male member 120 are easily entwined, the hydrophobic fibers can be arranged at the portion corresponding to the bottom portion 14 . In addition, by using hydrophobic fibers having a shape that is easily entangled at the tips of the projections 121 of the support male member 120 , the hydrophobic fibers can be arranged in the portion corresponding to the bottom portion 14 .

Further, a hydrophobic agent may be applied to the tips of the protrusions 121 of the support male member 120 used for manufacturing the nonwoven fabric 1 . When such a technique is adopted, it becomes possible to more finely control the region where the hydrophobicity is increased. Further, the bottom portion 14 can be subjected to hydrophobizing treatment by any method such as heat sealing.

As described above, the nonwoven fabric 1, which satisfies specific conditions for the density and orientation direction of the fibers and the hydrophobicity of the bottom portion is greater than that of other nonwoven fabrics, is used as the topsheet 2. Therefore, the diaper 10 according to the present embodiment It is possible to suppress the liquid return while being excellent in the liquid drawing property.

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

[Example 1]
A fiber web was produced using core-sheath type (PET/PE=5:5) thermoplastic fibers with a fineness of 1.8 dtex. The thermoplastic fibers are subjected to hydrophilic treatment with a hydrophilic agent. A fibrous web was placed on the male support material 120, and as shown in FIG. 7A, the female support material 130 was pushed into the male support material 120 from above the fibrous web 110 for 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 carry out fusion bonding, thereby producing a non-woven fabric.

The support male member 120 is provided with a prism-shaped protrusion 121 having a height of 8 mm. The projection 121 has a square shape of 2 mm×2 mm when viewed from above. The pitch of the prisms was 5 mm in each of the MD and CD directions. As the female support member 130 , a metal member having linear protrusions 131 with a width of 2 mm was used and pushed between the protrusions 121 of the male support member 120 . Adjacent projections 131, 131 on the support female member 130 are arranged at a pitch of 5 mm. The space for the fibers when the female support member 130 was pushed into the male support member 120 was 0.5 mm on one side, and the total length of both ends of the projections 121 of the male support member 120 was 1 mm.

The blowing treatment with the first hot air W1 was performed under conditions of a temperature of 160° C., a wind speed of 54 m/s, and a blowing time of 6 seconds. 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 obtained nonwoven fabric had a fineness of 1.8 dtex. The nonwoven fabric of Example 1 had ridges 12, bottom 14, and saddles 16 as shown in FIG.
A vat was filled with a hydrophobizing agent to a height of 0.5 mm, and the vat was immersed from the bottom 14 side to be hydrophobized, thereby obtaining a nonwoven fabric material of Example 1. As the hydrophobic agent, a solution of KF-96H-100,000cs (manufactured by Shin-Etsu Chemical Co., Ltd.) dissolved in hexane at 20% was used.

[Example 2]
The support female member 130 used in Example 1 was changed to one having projections 131A and 131B continuous in two orthogonal directions as shown in FIG. A nonwoven fabric was produced using a core-sheath type (PET/PE=5:5) thermoplastic fiber with a fiber diameter of 1.8 dtex by a method including the steps shown in FIG. The thermoplastic fibers are subjected to hydrophilization treatment. The blowing treatment with the first hot air W1 was performed under conditions of a temperature of 160° C., a wind speed of 54 m/s, and a blowing time of 6 seconds. 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 produced had ridges 12 , bottom 14 and saddles 16 . The same hydrophobic treatment as in Example 1 was applied to the bottom portion 14 to obtain a nonwoven fabric material of Example 2.

[Comparative Example 1]
The nonwoven fabric shown in FIG. 1 of JP-A-2012-136790 was produced using a thermoplastic fiber having a fineness of 1.8 dtex according to the manufacturing method described in the same publication, and the nonwoven fabric was used as a nonwoven fabric sample of Comparative Example 1. and

[Comparative Example 2]
A nonwoven fabric sample of Comparative Example 2 was produced in the same manner as in Example 1, except that the hydrophobic treatment was not performed.

[Comparative Example 3]
A nonwoven fabric sample of Comparative Example 3 was produced in the same manner as in Example 1, except that the hydrophilic agent was removed from the fiber surface by washing instead of performing the hydrophobizing treatment. The hydrophilizing agent was removed by ultrasonic cleaning while immersed in deionized water.

The nonwoven fabric samples of Examples and Comparative Examples were measured for fiber density and degree of orientation, and the contact angle to water was examined for the fibers collected from the nonwoven fabric samples. Furthermore, for each nonwoven fabric sample, the liquid flow distance and liquid return amount were measured by the following methods.

<Liquid flow distance>
The nonwoven fabric sample was cut into a size of 10 cm x 20 cm as a sample for evaluation, and fixed on a mounting portion inclined at 45 degrees with commercially available tissue paper interposed therebetween. 1 g of deionized water was injected over 10 seconds from a height of 10 mm above the sample for evaluation, and the flow of deionized water was observed. The liquid flow distance was measured from the vertical injection point to where the deionized water was drawn into the sample for evaluation.
The shorter the liquid flow distance, the easier the liquid permeates inside, that is, the better the liquid drawability.

<Liquid Return Amount>
120 g of physiological saline was injected into the horizontally placed nonwoven fabric, and left to stand for 10 minutes after completion of the injection. Advantech filter paper No. An absorbent sheet (mass M1) prepared by stacking 20 sheets of 5C (100 mm×100 mm) was placed on the nonwoven fabric sample. Further, a weight was placed so that a pressure of 3.5 kPa was applied around the injection point of the physiological saline solution. The mass of the filter paper after being placed for 1 minute was defined as M2, and (M2-M1) was defined as the liquid return amount. It is preferable that the liquid return amount is as small as possible.
The obtained results are summarized in Table 1 below together with other physical properties.

As shown in Table 1 above, the nonwoven samples of the examples have a lower fiber density in the wall region than in the top and bottom regions. Moreover, the nonwoven fabric samples of Examples have a high degree of fiber orientation of 60% or more in the wall region. Moreover, the contact angle with water is greater for fibers harvested from the bottom region than for fibers harvested from the top and wall regions, and the hydrophobicity of the bottom is relatively greater. Since these conditions are met, the nonwoven fabric materials of Examples have a smaller liquid flow distance than Comparative Examples 1 and 3, and a smaller amount of liquid return than Comparative Examples 1 and 2.
By using the nonwoven fabric material of the Examples as the surface sheet, an absorbent article having excellent liquid drawing property and reduced liquid return 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 embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, in the above-described embodiment, the diaper 10 was described as an example of the absorbent article, but the absorbent article of the present invention is not limited to such a diaper, but may be a sanitary napkin, a panty liner, an incontinence pad, or the like. It can be applied to various absorbent articles.

REFERENCE SIGNS LIST 1 nonwoven fabric 2 topsheet 3 backsheet 4 absorbent 10 absorbent article 12 ribs 12a top region 12b wall region 14 bottom 16 saddle 18, 18' hollow region

Claims (6)

An absorbent article comprising a liquid-permeable topsheet forming a skin-contacting surface and an absorbent body disposed on the non-skin-contacting side of the topsheet,
The surface sheet includes a plurality of ridges arranged in one direction so as to protrude from the skin-contacting surface, and having hollow regions on the non-skin-contacting surface side, a bottom provided between adjacent ridges, and the Made of a nonwoven fabric having ridge tops and saddles provided on at least one of the bottoms,
a pair of walls supporting the top of the ridge has a smaller number of fibers per unit area than the top and bottom of the ridge;
the bottom portion has fewer fibers per unit area than the top portion;
the bottom portion is more hydrophobic than the wall portion and the top portion of the ridge ;
The top is hydrophobic compared to the wall
absorbent article. The absorbent article according to claim 1, wherein a portion of the bottom portion is curved toward the skin contact surface side. The absorbent article according to claim 1 or 2, wherein the fibers of the wall portion are oriented in the thickness direction of the nonwoven fabric. 4. The absorbent article according to any one of claims 1 to 3 , wherein the non-skin-contacting surface of the top portion is more hydrophobic than the wall portion. The absorbent article according to any one of claims 1 to 4 , wherein the saddle is provided on the bottom so as to connect adjacent ridges. The saddle has a hollow area on the non-skin-contacting side,
6. The absorbent article according to claim 5 , wherein the hollow region of the ridge and the hollow region of the saddle form a communicating space between the nonwoven fabric and the absorbent body.

Images