JP6630085B2 - Absorbent articles - Google Patents

Description

  The present invention relates to an absorbent article.

In absorbent articles such as incontinence pads and sanitary napkins, it is widely known to use a surface sheet having a concavo-convex structure as a surface sheet for forming a skin-contacting surface from the viewpoint of improving liquid return prevention and stuffiness prevention. ing.
For example, in Patent Literature 1, a sheet for concavo-convex formation in which a large number of folds are formed in parallel with each other by folding is formed by joining a base material sheet between the folds. A sheet for a top sheet of an absorbent article having a concave-convex shape formed on a surface side in contact with the sheet.
Patent Literature 2 further includes a first fiber layer and a second fiber layer stacked and arranged on one surface side of the first fiber layer, and continuously extends in one direction on the first fiber layer side. A multi-layer nonwoven fabric is described in which a concavo-convex shape composed of a raised portion and a groove formed between the raised portions is formed.
Patent Literature 3 discloses an absorption sheet that includes an upper layer sheet and a lower sheet deformed into an uneven shape, and has a lower layer projection in which the lower sheet protrudes in the same direction at a position overlapping the projection of the upper layer sheet. A sheet for a topsheet of a cosmetic article is described.

JP 2002-165830 A JP 2008-25081 A JP 2009-118920 A

The present inventors have described that the surface sheet described in Patent Document 1 has unevenness formed by an unevenness forming sheet in which a large number of folds are formed by folding, and the thickness of the sheet forming the folds However, since it is basically the same over the entire area of the fold, it is flexibly deformed against compression in the thickness direction to provide a good touch, etc., but the wearer's skin is worn while wearing the absorbent article. It was found that there was room for improvement in the follow-up deformability when moving along the width direction.
In addition, the multilayer nonwoven fabric of Patent Document 2 does not have a hollow structure, so when used as a top sheet of an absorbent article, the follower deformability when the wearer's skin moves along the width direction is inferior, The skin is easily rubbed and becomes irritating to the skin.
Further, the surface sheet of Patent Document 3 also has room for improvement in the follow-up deformability when the wearer's skin moves along the width direction because the height of the convex portion is low.

  An object of the present invention is to provide an absorbent article that can solve the above-mentioned disadvantages of the related art.

  The present invention includes a liquid-permeable top sheet forming a skin contact surface, a back sheet forming a non-skin contact surface, and an absorber interposed between these sheets, and has a longitudinal direction and a width direction. An absorbent article, wherein the topsheet is an upper nonwoven fabric having an uneven structure in which convex portions and concave portions extending in the longitudinal direction are formed alternately in the width direction, and is formed on a bottom portion of the concave portion. A lower sheet joined to the upper layer nonwoven fabric at the joined portion, wherein the convex portion has a hollow structure, and the upper layer nonwoven fabric forms a side portion forming a side wall portion of the convex portion. The fiber density of the region is lower than the fiber density of the top region forming the top of the ridge and the fiber density of the bottom region forming the bottom of the concave ridge, and the height H of the ridge is An absorbent article which is larger than the interval P3 between the ridges in the width direction. A.

  According to the absorbent article of the present invention, when the wearer's skin moves in the width direction of the article during wearing, the ridges of the topsheet show good follow-up deformability, and rubbing with the skin does not easily occur. Difficult to irritate the skin.

FIG. 1 is a perspective view showing an incontinence pad according to the first embodiment of the present invention. FIG. 2A is an enlarged cross-sectional view taken along the line II-II of FIG. 1, and FIG. 2B is a plan view showing a part of a top sheet of the incontinence pad shown in FIG. 1. FIG. 3 is a schematic cross-sectional view showing a cross section along the thickness direction of the topsheet in the first embodiment. FIG. 4 is a schematic exploded cross-sectional view showing the top sheet shown in FIG. 3 virtually separated into an upper nonwoven fabric and a lower sheet. FIG. 5 is an explanatory diagram of an example of an introduction step of introducing a part of the lower sheet into the space on the back side of the ridge formed on the upper nonwoven fabric. FIG. 6 is a view for explaining a state in which constituent fibers constituting the nonwoven fabric 1 shown in FIG. 3 are fixed at the heat-sealed portion. FIG. 7 is a schematic view showing a manufacturing apparatus suitably used for manufacturing the topsheet 2 shown in FIG. FIG. 8 is a sectional view taken along line DD of FIG. FIGS. 9A to 8C are explanatory diagrams illustrating a state in which a plurality of small diameter portions and large diameter portions are formed in one constituent fiber between adjacent fused portions. FIG. 10 is a cross-sectional view (equivalent to FIG. 2A) illustrating an incontinence pad according to another embodiment of the present invention. FIG. 11 is a sectional view showing another absorber that can be used in the present invention.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.
FIG. 1 is a perspective view of an incontinence pad 10 (hereinafter, simply referred to as “incontinence pad 10”) according to a first embodiment of the present invention. FIG. 2A is an enlarged sectional view taken along the line II-II of FIG.
The incontinence pad 10 is, as shown in FIGS. 1 and 2, a liquid-permeable top sheet 2 forming a skin contact surface, a liquid-impermeable back sheet 3, and interposed between these two sheets 2, 3. The absorber 4 is provided. Liquid impermeability includes poor liquid permeability. The incontinence pad 10 has a vertically long shape, and has a longitudinal direction X and a width direction Y. The longitudinal direction X coincides with the front-rear direction of the wearer when the incontinence pad 10 is worn, and the width direction Y is a direction orthogonal to the longitudinal direction X in a plan view of the incontinence pad 10.

  The top sheet 2 and the back sheet 3 extend from the periphery of the absorber 4. An adhesive portion (not shown) for fixing the incontinence pad 10 to underwear such as shorts is provided on a surface (non-skin contact surface) of the incontinence pad 10 on the back sheet 3 side. The skin-contacting surface is a surface of the absorbent article or its component that faces the wearer's skin when worn, and the non-skin-contacting surface is an absorbent article or its component that This surface is directed to the side opposite to the skin side (usually, the underwear side).

  The absorbent body 4 of the incontinence pad 10 is composed of an absorbent core 40 and a core wrap sheet 45 covering substantially the entire surface thereof. The absorbent core 40 can be composed of, for example, a pile of absorbent fibers such as pulp or a mixed pile of absorbent fibers and an absorbent polymer. Examples of the liquid-absorbent fibers constituting the absorbent core 40 include cellulose-based hydrophilic fibers such as pulp fibers, rayon fibers, cotton fibers, and cellulose acetate. In addition to the cellulosic hydrophilic fibers, polyolefin fibers such as polyethylene and polypropylene, and condensed fibers such as polyester and polyamide may be contained. Examples of the absorbent polymer include sodium polyacrylate, (acrylic acid-vinyl alcohol) copolymer, crosslinked sodium polyacrylate, (starch-acrylic acid) graft copolymer, and (isobutylene-maleic anhydride) copolymer. And its saponified product, polyaspartic acid and the like. The fiber and the absorbent polymer can be used alone or in combination of two or more. As the core wrap sheet 45 that covers the absorbent core 40, for example, a liquid-permeable fiber sheet such as tissue paper or nonwoven fabric is preferably used. The core wrap sheet 45 may cover the entire absorbent core 40 with one sheet, or may cover the entire absorbent core 40 with two or more core wrap sheets. For example, the skin contact surface side and the non-skin contact surface side of the absorbent core 40 may be covered with separate sheets.

  As a material for forming the back sheet 3, various materials conventionally used for the back sheet of the absorbent article can be used without particular limitation. For example, a liquid-impermeable or water-repellent resin film, a resin film, A laminate sheet with a nonwoven fabric or the like can be used.

  Leak-proof cuffs 8 extending in the longitudinal direction are provided at positions on both sides of the incontinence pad 10 in the width direction Y on the skin contact surface side. The leak-proof cuff 8 has a free end 8a and a fixed area 8b which respectively extend in the longitudinal direction. The fixed area 8 b is located on the topsheet 2. The leak prevention cuff 8 is fixed to the topsheet 2 in the fixing area 8b. The fixed area 8b of the leak-proof cuff 8 extends outward in the width direction Y, and the extended portion and the width-extended portion of the back sheet 3 are joined to form the side flap 7. . In the leak prevention cuff 8, an elastic member 8c extending along the longitudinal direction X is attached to the free end 8a or a position near the free end 8a in an extended state. A plurality of elastic members 8c are arranged substantially parallel to each other. The part to which the plurality of elastic members 8c are attached forms a planar elastic region 8d. The planar elastic region 8d has a predetermined length along the width direction Y, and extends along the longitudinal direction X at least at the position of the wearer's excretion part-facing portion. The planar elastic region 8d is extendable and contractable along the longitudinal direction X. When the elastic member 8c contracts, the position between the free end 8a and the fixed area 8b of the leak-preventing cuff 8 rises substantially in an L-shape toward the body side of the wearer, and the planar elasticity is increased. The region 8d comes into contact with the wearer's skin to prevent lateral leakage of the liquid.

As shown in FIGS. 2A and 2B, the topsheet 2 of the incontinence pad 10 according to the first embodiment has streak-like ridges 13 and concave ridges extending in the longitudinal direction X of the incontinence pad 10. 14 is a nonwoven fabric 1 (upper layer nonwoven fabric) having a concavo-convex structure formed alternately in the width direction Y of the incontinence pad 10, and a lower side joined to the nonwoven fabric 1 at a joint 14 s formed at the bottom of the concave ridge 14. The protruding portion 13 has a hollow structure.
In the nonwoven fabric 1 having the concavo-convex structure constituting the topsheet 2, the “one direction” in which the convex ridges 13 and the concave ridges 14 extend are the same direction as the longitudinal direction X of the incontinence pad 10. The “one direction” in which the portion 13 and the concave ridge 14 extend is also referred to as an X direction.

  As shown in FIGS. 2A and 3, the nonwoven fabric 1 has a plurality of ridges 13 in which the cross-sectional shapes of the front and back surfaces a and b are both convex upward in the thickness direction (Z direction). It has a concave ridge portion 14 located between the adjacent convex ridge portions 13, 13. The cross-sectional shape of the front and back surfaces a and b of the concave ridge portion 14 is concave toward the upper side in the thickness direction (Z direction) of the nonwoven fabric. In other words, the cross-sectional shape of both the front and back surfaces a and b of the concave ridge portion 14 is convex toward the lower side in the thickness direction (Z direction) of the nonwoven fabric. The plurality of ridges 13 extend continuously in one direction (X direction) of the nonwoven fabric 1, and the plurality of concave ridges 14 also extend in a groove shape continuously extending in one direction X of the nonwoven fabric 1. Has made. The ridges 13 and the recesses 14 are parallel to each other and are alternately arranged in a direction (Y direction) orthogonal to the one direction (X direction).

  As described later, the nonwoven fabric 1 is manufactured by subjecting the fiber sheet 1a to an uneven process using a pair of uneven rolls 401 and 402 that mesh with each other. The one direction (X direction) of the nonwoven fabric 1 described above is the same direction as the machine direction (MD, flow direction) when the nonwoven fabric 1 is manufactured by performing uneven processing on the fiber sheet 1a. The direction (Y direction) orthogonal to the direction (X direction) is the same direction as the orthogonal direction (CD, roll axis direction) orthogonal to the machine direction (MD, flow direction).

The nonwoven fabric 1 includes a top region 13a, a bottom region 13b, and a side region 13c located therebetween when the nonwoven fabric 1 is viewed in cross section along the thickness direction Z as shown in FIG. The top region 13a, the bottom region 13b, and the side region 13c extend continuously in one direction (X direction) of the nonwoven fabric 1.
The top region 13a, the bottom region 13b, and the side region 13c divide the thickness T (see FIG. 3) of the nonwoven fabric 1 in the Z direction into three equal parts when the nonwoven fabric 1 is viewed in cross section along the thickness direction Z, and A portion above Z is distinguished as a top region 13a, a center portion is identified as a side region 13c, and a portion below Z is identified as a bottom region 13b.

  As shown in FIGS. 3 and 4, when the nonwoven fabric 1 is observed along the thickness direction Z, the fiber density of the side region 13c is lower than the fiber density of the top region 13a and the fiber density of the bottom region 13b. I have. The fiber density refers to the number of fibers per unit area in the cross section of the nonwoven fabric 1. Therefore, the side area 13c is a sparse area in which the number of fibers is small (the distance between fibers is large) as compared with the top area 13a and the bottom area 13b. In order to impart such a fiber density to the side region 13c, the nonwoven fabric 1 may be manufactured according to a manufacturing method described later.

The ratio (D _13c / D _13a , D _13c / D _13b ) of the fiber density ( _D13c ) of the side region 13c to the fiber density (D _13a ) at the top region 13a or the fiber density (D _13b ) at the bottom region 13b. Is preferably 0.15 or more and 0.9 or less, more preferably 0.2 or more and 0.8 or less. Specifically, the specific values of the fiber density of the nonwoven fabric 1, the fiber density _{(D 13a)} at the top region 13a is preferably 90 present / mm ² or more 200 present / mm ² or less, more preferably 100 / mm ² or more and 180 / mm ² or less. Also, the fiber density _{(D 13b)} at the bottom area 13b is preferably 80 present / mm ² or more 200 present / mm ² or less, more preferably 90 present / mm ² or more 180 lines / mm ² or less. The fiber density of the side region 13c _{(D 13c)} is preferably 30 lines / mm ² or more eighty / mm ² or less, more preferably 40 present / mm ² or more 70 yarns / mm ² or less. The method for measuring the fiber density is as follows.

[Method of measuring fiber density in top region 13a, bottom region 13b and side region 13c]
The nonwoven fabric is cut along the thickness direction Z using a feather razor (product number FAS-10, manufactured by Feather Safety Razor Co., Ltd.). Regarding the fiber density in the top region 13a, the top region 13a, which is the upper region when the thickness of the cut surface of the nonwoven fabric is divided into three equal parts in the Z direction, is enlarged and observed using a scanning electron microscope (when the fiber cross section is 30 to 30). The magnification is adjusted to about 60 fibers that can be measured; 150 to 500 times), and the number of cross sections of the fiber cut by the cut surface per fixed area (about 0.5 mm ² ) is counted. Next, the fiber density is converted into the number of cross sections of the fiber per 1 mm ² , which is defined as the fiber density in the top region 13a. The measurement is performed at three places, and the average is defined as the fiber density of the sample. Similarly, the fiber density in the bottom region 13b is determined by measuring the lower part when the thickness of the cut surface of the nonwoven fabric is divided into three equal parts in the Z direction. Similarly, the fiber density of the side region 13c is determined by measuring the central portion when the thickness of the cut surface of the nonwoven fabric is divided into three equal parts in the Z direction. In addition, JCM-5100 (trade name) manufactured by JEOL Ltd. is used as the scanning electron microscope.

In the topsheet 2, the top of the ridge 13 is formed from the top region 13 a of the nonwoven fabric 1, the bottom of the ridge 14 is formed from the bottom region 13 b of the nonwoven fabric 1, and the side wall of the ridge 13 is formed. The part is formed from the side area 13 c of the nonwoven fabric 1. Therefore, the fiber density of the side area 13 c of the nonwoven fabric 1 constituting the side wall of the convex ridge 13 is the fiber density of the top area 13 a forming the top of the convex ridge and the bottom area forming the bottom of the concave ridge 14. 13b is lower than the fiber density.
Further, in the topsheet 2 in the present embodiment, as shown in FIG. 3, the height H of the ridge 13 is larger than the interval P3 of the ridge 13 in the width direction Y.

According to the incontinence pad 10 of the present embodiment, the incontinence pad 10 has moved along the width direction Y due to the wearer's motion, for example, the standing and sitting motion, the lying motion, the walking motion, etc. during the wearing. In this case, the ridges 13 of the topsheet 2 have a hollow structure, and the side walls of the ridges 13 are formed from the side regions 13c of the nonwoven fabric 1 having a low fiber density and are easily bent. The vicinity of the top moves along the width direction of the incontinence pad 10 following the skin of the wearer, and reduces friction between the skin of the wearer and the topsheet 2.
In addition, the vicinity of the top of the ridge 13 shows good cushioning properties against pressure in the thickness direction of the topsheet 2.
In addition, according to the incontinence pad 10 of the present embodiment, the height H of the protruding ridge portion 13 is high, whereby the movable area becomes large, and the effect of alleviating rubbing with the skin increases. In addition, an advantageous effect of improving cushioning in the thickness direction can be obtained. However, on the other hand, if the height H of the ridges 13 is simply increased, the ridges 13 are likely to fall down from the base, whereby the vicinity of the top of the ridges 13 tends to exhibit the effect of reducing friction. It is difficult to contact the skin. In this regard, in the present embodiment, the interval P3 between the ridges 13 is made smaller than the height H of the ridges 13 so that the ridges 13 support each other to make it difficult to fall down. The effect of alleviating rubbing against the skin and the cushioning property in the thickness direction can be improved while preventing adverse effects.

  In light of the effect of alleviating rubbing against the skin and improving the cushioning property in the thickness direction, the height H of the ridge 13 is preferably 1.1 times or more, and more preferably, the distance P3 between the ridges 13. Is 1.5 times or more, and from the viewpoint of preventing the ridge from falling down, is preferably 5 times or less, more preferably 3 times or less, and has an effect of alleviating rubbing with the skin and improving cushioning properties in the thickness direction. From the viewpoint of achieving both the prevention of the protrusion from falling down, the ratio is preferably 1.1 to 5 times, more preferably 1.5 to 3 times.

From the same viewpoint, the height H of the ridge 13 is preferably 1.1 mm or more, more preferably 1.5 mm or more, and preferably 12 mm or less, more preferably 9 mm or less, and preferably 1 mm or less. 0.1 mm or more and 12 mm or less, more preferably 1.5 mm or more and 9 mm or less. From the same viewpoint, the thickness T of the nonwoven fabric 1 (the thickness of the uneven structure portion, see FIG. 3) is preferably 1.1 mm or more, more preferably 1.5 mm or more, and preferably 12 mm or less, more preferably 9 mm. Or less, preferably 1.1 mm or more and 1.5 mm or less, more preferably 12 mm or more and 9 mm or less.
From the same viewpoint, the interval P3 of the ridge 13 is preferably 1 mm or more, more preferably 1.5 mm or more, and preferably 10 mm or less, more preferably 8 mm or less, and preferably 1 mm to 10 mm. Or less, more preferably 1.5 mm or more and 8 mm or less.

Further, as shown in FIG. 3, the top sheet 2 in the present embodiment has a portion 60 of the lower sheet 6 in the space on the back side of the ridge portion 13, and a portion in the space. The maximum height h6 of 60 is not less than 1/5 and not more than 2/3 of the height H of the ridge 13. The space on the back side of the ridge 13 is a space formed on the back surface b side of the portion forming the ridge 13 of the nonwoven fabric 1, and the lower sheet 6 enters into the space. Regardless of whether or not they are called spaces. On the other hand, as to whether or not the ridge 13 has a hollow structure, the maximum height h6 (see FIG. 3) of the portion 60 of the lower sheet 6 that enters the space is determined by the height of the ridge 13. If it is more than 2/3 of H, it is determined that the ridge 13 does not have a hollow structure, and if the maximum height h6 is 2/3 or less of the height H of the ridge 13, it is convex. It is determined that the ridge 13 has a hollow structure. However, even if it is more than 2/3 of the height H of the ridge 13, the height between the upper nonwoven fabric 1 and the lower sheet 6 is 10% or more of the height H of the ridge. However, when there is a space in which no fiber exists, the ridge has a hollow structure.
In addition, as shown in FIG. 3, the height H of the ridge 13 and the maximum height h6 of the portion 60 are all the heights of the boundary between the nonwoven fabric 1 and the lower sheet 6 at the bottom of the ridge 14. The distance from the height position B to the highest positions 13t and 6t.

Since the part 60 of the lower sheet 6 enters the space on the back side of the ridge 13, the root of the ridge 13 is reinforced and the ridge 13 is hard to fall. This makes it easier to bring the vicinity of the top of the ridge 13 into contact with the skin in a state in which the effect of reducing friction is likely to be exhibited.
From such a viewpoint, the maximum height h6 of the portion 60 of the lower sheet 6 that enters the space on the back side of the ridge 13 (hereinafter, also referred to as the ridge inner portion 60) is equal to the height of the ridge 13. H is preferably 1/5 or more, more preferably 1/4 or more, still more preferably 1/3 or more, and preferably 2/3 or less, and still more preferably 1/3 or less. It is not less than / 3 and not more than 2/3.

When dividing the upper nonwoven fabric 1 into the top region 13a, the side region 13c, and the bottom region 13b, the thickness T of the nonwoven fabric divided into three equal parts, the height H of the ridge 13, the interval P3 of the ridge 13, and the height The maximum height h6 of the inner portion 60 can be measured by the following method.
The upper nonwoven fabric 1 and the lower sheet 6 are integrally cut in the thickness direction Z using a feather razor (product number FAS-10, manufactured by Feather Safety Razor Co., Ltd.). The cross section is magnified about 20 times by a digital microscope VHX-900 manufactured by KEYENCE and measured.

In the incontinence pad 10 according to the present embodiment, as shown in FIGS. 3 and 4, similarly to the nonwoven fabric 1, the lower sheet 6 is also formed of a fiber aggregate, and the convexity of the nonwoven fabric 1 in the lower sheet 6. The fiber density of the protruding ridge portion 60, which is the portion that enters the space on the back side of the ridge, is higher than the fiber density in the side region 13c of the nonwoven fabric 1 described above. That is, the number of fibers per unit area in a cross section of the lower sheet 6 has become larger than the number per unit area in a cross section of the nonwoven fabric 1, convex portions in the portion 60 of the lower sheet 6, the nonwoven fabric 1 the number of fibers than the side region 13c is large and has a small dense area of the fiber distances. The magnitude relationship between the fiber densities is such that, in the method of manufacturing the topsheet 2 described later, the draw ratio of the fiber sheet 1a is adjusted so that the fiber density in the side region 13c is lower than the fiber density of the ridge inner portion 60. Good. In addition, the fiber aggregate forming the lower sheet 6 includes a nonwoven fabric, a nonwoven fabric web, a laminate thereof, and the like.
3 and 4, the constituent fibers of the lower sheet 6 are shown more densely than the constituent fibers of the nonwoven fabric 1 over the entire area of the lower sheet 6. This is for the sake of convenience for distinguishing from the sheet 6 .

  Since the fiber density of the ridge inner portion 60 is higher than the fiber density of the side region 13c of the nonwoven fabric 1, the root of the ridge 13 is efficiently formed while maintaining the following deformation of the top region 13a of the nonwoven fabric 1. This makes it easier to bring the vicinity of the top of the ridge 13 into contact with the skin in a state where the effect of alleviating rubbing is easily exhibited. In addition, due to the density gradient of the fibers from the side region 13 c of the nonwoven fabric 1 to the inner portion 60 of the ridge portion, the ability of the liquid to be drawn into the absorber 4 via the topsheet 2 is improved.

From such a viewpoint, the ratio (D ₁₆ / D _13c ) of the fiber density (D ₁₆ ) of the inner portion 60 of the ridge portion of the lower sheet 6 to the fiber density (D _13c ) of the side region 13c is preferably 1. It is 1 or more and 8.3 or less, and more preferably 1.3 or more and 5.5 or less. As a specific value, the fiber density of the convex portions in section 60 _{(D 13c)} are preferably 40 present / mm ² or more 250 lines / mm ² or less, more preferably 80 present / mm ² or more 220 present / mm ² It is as follows.
The method for measuring the fiber density of the inner portion 60 of the ridge portion of the lower sheet 6 is as follows.

[Method of Measuring Fiber Density of Inner Part 60]
Using a feather razor (product number FAS-10, manufactured by Feather Safety Razor Co., Ltd.), the cut surface of the inner portion 60 of the ridge obtained by cutting the topsheet 2 along the thickness direction Z is used as the top region 13a described above. In the same manner as in the method for measuring the fiber density of the above, the number of cross sections of the fiber per 1 mm ^{2 of} the cut surface (an average value at three places) was obtained in the same manner, and the obtained value was used as the fiber density of the inner portion 60 of the ridge. And
When measuring the fiber density of the ridge inner portion 60, a portion located in the same height range as the side region 13 c of the nonwoven fabric 1 in the cross section of the ridge inner portion 60 along the thickness direction of the topsheet 2. From the cross section of, the fiber density at the portion is determined. If the inner portion 60 does not enter the same height as the side area 13c of the nonwoven fabric 1, the fiber density at the top of the inner portion 60 is determined.
In addition, as shown in FIG. 5B, in the case where the inner portion 60 has an outer portion close to the nonwoven fabric 1 and an inner portion far from the nonwoven fabric 1, the fiber density of the outer portion is determined.

  FIGS. 5A and 5B are explanatory diagrams of a first method which is an example of a method of forming the inner portion 60 on the lower sheet 6. In the first method, the nonwoven fabric 1 that has been deformed into an uneven shape having the ridges 13 and the recesses 14 in the stretching step of the method for manufacturing the topsheet 2 described below is coated with the upper layer fiber at the bottom of the recesses 14. After joining with the lower sheet 6 composed of a laminated sheet having the layer 61 and the lower fiber layer 62, the lower fiber layer 62 in the lower sheet 6 is thermally contracted, so that the upper fiber layer 61 side is The inner portion 60 is formed so as to protrude toward the back side space.

The lower fiber layer 62 contains heat-shrinkable fibers to be shrunk by heat treatment, and the upper fiber layer 61 contains non-heat-shrinkable fibers that do not shrink at the shrinkage starting temperature of the heat-shrinkable fibers.
As the heat-shrinkable fiber contained in the lower fiber layer 62, a known heat-shrinkable fiber can be used without any particular limitation, and it is more preferable to use a latently crimpable fiber. The latently crimpable fiber is one that develops a helical crimp by heat treatment and shrinks. For example, an eccentric core-sheath type composite fiber or a side-by-side composite fiber containing two types of thermoplastic polymer materials having different shrinkage rates. -Consists of side-type composite fibers. Examples thereof include those described in JP-A-9-296325 and JP-A-2759331. As an example of two kinds of thermoplastic polymer materials having different shrinkage rates, for example, a combination of an ethylene-propylene random copolymer (EP) and a polypropylene (PP) is preferably mentioned. The lower fiber layer 62 may be composed of 100% heat-shrinkable fibers or may include other fibers. When other fibers are included, the amount of the heat-shrinkable fibers is preferably 50% by mass or more, and particularly preferably 70 to 90% by mass, based on the mass of the lower fiber layer 62.

The non-heat-shrinkable fibers included in the upper fiber layer 61 are fibers that do not exhibit heat shrinkage, and exhibit heat shrinkage, but are substantially below the heat shrinkage onset temperature of the heat-shrinkable fibers included in the lower fiber layer. Includes both non-heat shrinkable fibers. Further, the upper fiber layer 61 may contain heat-fusible fibers including a heat-fusible resin having a melting point T _M higher than the heat shrinkage initiation temperature T _S of the heat-shrinkable fibers contained in the lower fiber layer 62. preferable. The heat-fused fiber is contained in an amount of preferably 70% by mass or more, more preferably 80% by mass or more, based on the mass of the heat-fused resin, based on the mass of the upper fiber layer 61. Most preferably, the non-heat-shrinkable fibers constituting the upper fiber layer 61 are composed of 100% by mass of the heat-fusible fibers.
Similarly, the upper non-woven fabric 1 also contains heat-fusible fibers containing a heat-fusible resin having a melting point T _M higher than the heat-shrink start temperature T _S of the heat-shrinkable fibers contained in the lower fiber layer 62. Is preferred. The heat-fused fiber is contained in an amount of preferably 70% by mass or more, more preferably 80% by mass or more, based on the mass of the upper nonwoven fabric 1, based on the mass of the heat-fused resin. Most preferably, the non-heat-shrinkable fibers constituting the upper nonwoven fabric 1 are composed of 100% by mass of the heat-fusible fibers.

In the method for manufacturing the topsheet 2 of the first method, the distance between the joints 14s between the upper nonwoven fabric 1 and the lower sheet 6 decreases with the heat shrinkage of the lower fiber layer 62. It is easy to obtain the convex ridge 13 in which the ratio of the height H of the convex ridge 13 to the distance P3 is large.
In particular, despite the fact that the fiber density of the side area 13c of the nonwoven fabric 1 is lower than the fiber density of the top area 13a, the height H of the ridge 13 is larger than the interval P3 between the ridges 13. Is easily obtained.
The ridge 13 in the topsheet 2 shown in FIG. 3 has an Ω-shaped cross section. As shown in FIG. 4, the Ω-shaped cross-sectional shape is a shape having a wide portion on the top side in the height direction of the ridge portion 13, the length of the width direction Y being longer than the narrow portion on the base side. It is. The surface sheet 2 in which the cross-sectional shape of the ridges 13 is Ω-shaped has advantages such as improved followability to the skin and alleviation of rubbing with the skin. For example, the topsheet is manufactured by the first method. can do.
A preferred method of manufacturing the topsheet 2 including the first method will be described later.

A preferred configuration of the nonwoven fabric 1 constituting the topsheet 2 will be described with reference to FIGS.
The constituent fibers 11 of the nonwoven fabric 1 include high elongation fibers. Here, the high elongation fiber included in the constituent fiber 11 means not only a fiber having a high elongation at the stage of the raw material fiber, but also a fiber having a high elongation at the stage of the manufactured nonwoven fabric 1. As the “high elongation fiber”, excluding stretchable fiber having elasticity (elastomer) and extensibility, for example, melt spinning at low speed as described in paragraph [0033] of JP-A-2010-168715 to form a composite After the fiber is obtained, the heat obtained by performing a heat treatment and / or a crimping treatment without performing a stretching treatment changes the crystalline state of the resin and extends the length of the heat-extensible fiber, or polypropylene or polyethylene. Or a fiber produced by using a resin such as a resin and spinning at a relatively low speed, or a low crystallinity polyethylene-polypropylene copolymer or polypropylene, and dry-blending polyethylene and spinning. Is mentioned. Among these fibers, the high elongation fiber is preferably a core-sheath type composite fiber having heat-fusibility. The core-sheath type composite fiber may be a concentric core-sheath type, an eccentric core-sheath type, a side-by-side type, or a deformed type, but is preferably a concentric core-sheath type. Regardless of the form of the fiber, the fineness of the high elongation fiber is 1.0 dtex or more and 10.0 dtex or less at the raw material stage from the viewpoint of producing a soft and soft nonwoven fabric or the like. And more preferably 2.0 dtex or more and 8.0 dtex or less.

  The constituent fibers 11 of the nonwoven fabric 1 may include other fibers in addition to the high elongation fibers, but are preferably formed only of the high elongation fibers. As other fibers, for example, a non-heat-extensible core-sheath type heat-fusible conjugate fiber containing two components having different melting points and subjected to a stretching treatment, or a fiber originally having no heat-fusibility ( For example, natural fibers such as cotton and pulp, rayon and acetate fibers, and the like can be mentioned. When the nonwoven fabric 1 is configured to include other fibers in addition to the high elongation fibers, the proportion of the high elongation fibers in the nonwoven fabric 1 is preferably 50% by mass or more and 100% by mass or less, more preferably It is 80% by mass or more and 100% by mass or less.

  The heat extensible fiber that is a high elongation fiber is a composite fiber that has been subjected to an unstretched treatment or a weakly stretched treatment at a raw material stage, and includes, for example, a first resin component constituting a core portion and a sheath portion. A second resin component containing a polyethylene resin, and the first resin component has a higher melting point than the second resin component. The first resin component is a component that expresses heat extensibility of the fiber, and the second resin component is a component that expresses heat fusibility. The melting points of the first resin component and the second resin component were determined by using a differential scanning calorimeter (DSC6200 manufactured by Seiko Instruments Inc.) in a thermal analysis of a finely cut fiber sample (sample weight 2 mg) at a heating rate of 10 ° C./min. The melting peak temperature of each resin is measured and defined by the melting peak temperature. If the melting point of the second resin component cannot be clearly measured by this method, the resin is defined as "a resin having no melting point". In this case, as the temperature at which the flow of the molecules of the second resin component starts, the temperature at which the second resin component fuses to the extent that the fusion point strength of the fiber can be measured is used as the softening point, and this is used instead of the melting point.

The second resin component constituting the sheath portion includes a polyethylene resin as described above. Examples of the polyethylene resin include low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE). In particular, a high-density polyethylene having a density of 0.935 g / cm ³ or more and 0.965 g / cm ³ or less is preferable. The second resin component constituting the sheath is preferably a polyethylene resin alone, but other resins may be blended. Other resins to be blended include polypropylene resin, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH) and the like. However, as for the 2nd resin component which comprises a sheath part, it is preferable that 50 mass% or more in the resin component of a sheath part is 70 mass% or more and 100 mass% or less of a polyethylene resin. The polyethylene resin preferably has a crystallite size of 10 nm or more and 20 nm or less, more preferably 11.5 nm or more and 18 nm or less.

  As the first resin component constituting the core portion, a resin component having a higher melting point than the polyethylene resin which is the resin constituting the sheath portion can be used without any particular limitation. Examples of the resin component forming the core include a polyolefin-based resin (excluding polyethylene resin) such as polypropylene (PP), and a polyester-based resin such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Further, a polyamide polymer, a copolymer having two or more kinds of resin components, or the like can also be used. A plurality of types of resins may be blended and used. In this case, the melting point of the core is the melting point of the resin having the highest melting point. The difference between the melting point of the first resin component forming the core portion and the melting point of the second resin component forming the sheath portion (the former-the latter) is 20 ° C. or more because the nonwoven fabric is easily manufactured. And preferably 150 ° C. or lower.

  The preferred orientation index of the first resin component in the heat-extensible fiber that is a high elongation fiber is naturally different depending on the resin used. For example, when the first resin component is a polypropylene resin, the orientation index may be 60% or less. It is preferably at most 40%, more preferably at most 25%. When the first resin component is a polyester, the orientation index is preferably 25% or less, more preferably 20% or less, and further preferably 10% or less. On the other hand, the second resin component preferably has an orientation index of 5% or more, more preferably 15% or more, and still more preferably 30% or more. The orientation index is an index of the degree of orientation of the polymer chains of the resin constituting the fiber.

  The orientation index of the first resin component and the second resin component is determined by the method described in paragraphs [0027] to [0029] of JP-A-2010-168715. Further, a method of achieving each of the resin components in the heat extensible conjugate fiber to have the above-described orientation index is described in paragraphs [0033] to [0036] of JP-A-2010-168715.

  In addition, the elongation of the high elongation fiber at the stage of the raw material is preferably 100% or more and 800% or less, more preferably 200% or more and 500% or less, and further preferably 250% or more and 400% or less. By using a high elongation fiber having an elongation in this range, the fiber is successfully stretched in a drawing device, and the above-mentioned transition point from the small diameter portion to the large diameter portion is adjacent to the fused portion. , Feel good.

  The elongation of the high elongation fiber is based on JISL-1015, and is based on measurement under the conditions of measurement environment temperature / humidity 20 ± 2 ° C, 65 ± 2% RH, gripping distance of a tensile tester 20 mm, and tensile speed 20 mm / min. And In addition, if the grasping interval cannot be set to 20 mm, that is, when the elongation is measured by collecting fibers from the already manufactured nonwoven fabric, that is, if the length of the fiber to be measured is less than 20 mm, the grasping interval is changed. Measure at 10 mm or 5 mm.

  The ratio (mass ratio, former: latter) of the first resin component to the second resin component in the high elongation fiber is from 10:90 to 90:10, particularly from 20:80 to 80:20, particularly from the raw material stage. The ratio is preferably 50:50 to 70:30. As the fiber length of the high elongation fiber, a fiber having an appropriate length is used depending on the method of producing the nonwoven fabric. When the nonwoven fabric is manufactured by a card method as described later, for example, the fiber length is preferably about 30 to 70 mm.

  The fiber diameter of the high elongation fiber is preferably 10 μm or more and 35 μm or less, particularly preferably 15 μm or more and 30 μm or less. The fiber diameter is measured by the following method.

[Measurement of fiber diameter of fiber]
As the fiber diameter of the fiber, the fiber diameter (μm) is measured by observing the cross section of the fiber at a magnification of 200 to 800 times using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.). The cross section of the fiber is obtained by cutting the fiber using a feather razor (product number FAS-10, manufactured by Feather Safety Razor Co., Ltd.). The fiber diameter of one extracted fiber when it is approximated to a circle is measured at five points, and the average value of the five measured values is defined as the fiber diameter.

  At the raw material stage, as the heat-extensible fiber that is a high elongation fiber, in addition to the above-described heat-extensible fiber, Japanese Patent No. 4131852, JP-A-2005-350836, JP-A-2007-303035, The fibers described in JP-A-2007-204899, JP-A-2007-204901, JP-A-2007-204902, and the like can also be used.

  As shown in FIG. 6, the nonwoven fabric 1 focuses on one of the constituent fibers 11 of the nonwoven fabric 1, and the constituent fiber 11 is placed between the adjacent fused portions 12, 12. It has a large-diameter portion 17 having a large fiber diameter sandwiched between two small-diameter portions 16 having a small fiber diameter. Specifically, as shown in FIG. 6, focusing on one of the constituent fibers 11 of the nonwoven fabric 1, the fusion point formed by thermally fusing the intersection with the other constituent fibers 11 is formed. A small diameter portion 16 having a small fiber diameter extends from the attachment portion 12 with substantially the same fiber diameter. Paying attention to the one constituent fiber 11, a large diameter portion 17 having a larger fiber diameter than the small diameter portion 16 is provided between the small diameter portions 16, 16 extending from the adjacent fused portions 12, 12, respectively. Are formed to extend with substantially the same fiber diameter. More specifically, the nonwoven fabric 1 focuses on one constituent fiber 11, and moves from one fused portion 12 of the adjacent fused portions 12 to the other fused portion 12 toward one fused portion 12. The component fibers 11 are arranged in the order of the small diameter portion 16 on the attachment portion 12 side, one large diameter portion 17, and the small diameter portion 16 on the other fusion portion 12 side.

As described above, the presence of the low-rigidity small-diameter portion 16 adjacent to the fused portion 12 where the rigidity of the nonwoven fabric 1 increases increases the flexibility of the nonwoven fabric 1 and improves the feel. In addition, the more the plurality of large diameter portions 17 are provided, in other words, the more the low-rigidity small diameter portions 16 are present in the constituent fibers 11, the more the flexibility of the nonwoven fabric 1 is improved, and the better the touch is.
Since the nonwoven fabric 1 has such a configuration, when the wearer's skin moves in the width direction Y, the ridges 13 (convex portions) bend more easily in the width direction Y, and follow the skin. The deformability is improved, and the occurrence of discomfort during wearing is further prevented.

  As shown in FIG. 6, the nonwoven fabric 1 focuses on one constituent fiber 11 of the constituent fibers 11 of the nonwoven fabric 1, and has a plurality of large-diameter portions 17 between adjacent fused portions 12. (Two in the nonwoven fabric 1). More specifically, the nonwoven fabric 1 focuses on one constituent fiber 11, and moves from one fused portion 12 of the adjacent fused portions 12 to the other fused portion 12 toward one fused portion 12. The constituent fibers arranged in the order of the small-diameter portion 16 on the bonding portion 12 side, the first large-diameter portion 17, the small-diameter portion 16, the second large-diameter portion 17, and the other small-diameter portion 16 on the fused portion 12 side 11 is provided. The nonwoven fabric 1 focuses on one constituent fiber 11 and preferably forms one large-diameter portion 17 between adjacent fused portions 12, 12 from the viewpoint of improving the feel and reducing the strength of the nonwoven fabric. More than five or less, more preferably more than one and three or less.

The ratio (L ₁₆ / L ₁₇ ) of the fiber diameter (diameter L ₁₆ ) of the small diameter portion 16 to the fiber diameter (diameter L ₁₇ ) of the large diameter portion 17 is preferably 0.5 or more and 0.8 or less, more preferably 0 or less. .55 or more and 0.7 or less. Specifically, the fiber diameter (diameter L ₁₆ ) of the small diameter portion 16 is preferably 5 μm or more and 28 μm or less, more preferably 6.5 μm or more and 20 μm or less, particularly preferably 7.5 μm or more and 16 μm or less, from the viewpoint of improving the feel. is there. The fiber diameter (diameter L ₁₇ ) of the large diameter portion 17 is preferably 10 μm or more and 35 μm or less, more preferably 13 μm or more and 25 μm or less, and particularly preferably 15 μm or more and 20 μm or less, from the viewpoint of improving the feel.
The fiber diameters (diameters L ₁₆ and L ₁₇ ) of the small diameter portion 16 and the large diameter portion 17 are measured in the same manner as the measurement of the fiber diameter of the fiber described above.

  The nonwoven fabric 1 focuses on one constituent fiber 11 of the constituent fibers 11 of the nonwoven fabric 1, and a change point 18 from the small diameter portion 16 adjacent to the fusion portion 12 to the large diameter portion 17 is determined by the fusion point. It is preferable that the gaps are arranged in a range of １ ／ of the interval T between the fusion parts 12, 12 adjacent to the fusion part 12. Here, the change point 18 of the nonwoven fabric continuously changes gradually from the small diameter portion 16 extending with a small fiber diameter to the large diameter portion 17 extending with a fiber diameter larger than the small diameter portion 16. It does not include a part or a part that continuously changes over a plurality of stages, and means a part where the fiber diameter changes extremely one step. When the one constituent fiber 11 is a heat-extensible conjugate fiber, the change point 18 of the nonwoven fabric of the present invention is defined as a first resin component forming the core portion and a second resin forming the sheath portion. It does not include the state where the fiber diameter changes due to peeling off from the components, but simply means the part where the fiber diameter changes due to stretching.

  Further, that the changing point 18 is arranged within the range of 1/3 of the interval T between the fused portions 12 and 12 adjacent to the fused portion 12 means that the constituent fibers 11 of the nonwoven fabric 1 are randomly extracted. As shown in FIG. 6, the constitutive fibers 11 are separated from each other by using JCM-5100 (trade name) manufactured by JEOL Ltd. as a scanning electron microscope. Magnify (100-300x) so that it can be observed. Next, the interval T between the centers of the adjacent fusion parts 12, 12 is divided into three equal parts to form a region AT on the one fusion part 12 side, a region BT on the other fusion part 12 side, and a central area CT. Classify. This means that the change point 18 is located in the area AT or the area BT. Further, the nonwoven fabric 1 in which the change point 18 is disposed within a range of 1/3 of the interval T between the fused portions 12 adjacent to the fused portion 12 is the same as the nonwoven fabric 1 except that the constituent fibers 11 of the nonwoven fabric 1 This means that the nonwoven fabric has at least one or more constituent fibers 11 in which the change points 18 are arranged in the area AT or the area BT when randomly extracted. Specifically, the number is preferably one or more, more preferably five or more, and particularly preferably ten or more, from the viewpoint of improving the touch.

In the nonwoven fabric 1 of the present embodiment, the number of fibers having a change point in the constituent fibers constituting the side region 13c is the number of fibers having the change point 18 in the constituent fibers constituting the top region 13a, and The number of the fibers having the changing point 18 is larger than the number of the fibers having the changing point 18 in the constituent fibers constituting the bottom region 13b. The number of fibers having a change point 18 in the constituent fibers constituting the top region 13a (N _13a ), or the side region 13c with respect to the number of fibers having the change point 18 in the constituent fibers constituting the bottom region 13b (N _13b ). The ratio (N _13c / N _13a , N _13c / N _13b ) of the number (N _13c ) of fibers having a change point in the constituent fibers to be formed is preferably 2 or more and 20 or less, more preferably 5 or more and 20 or less. Specifically, regarding the specific value of the number of fibers having the changing point 18 of the nonwoven fabric 1, the number of fibers (N _13a ) having the changing point 18 in the constituent fibers constituting the top region 13a is preferably one or more. It is 15 or less, more preferably 5 or more and 15 or less. The number (N _13b ) of the fibers having the change point 18 in the constituent fibers constituting the bottom region 13b is preferably 1 or more and 15 or less, more preferably 5 or more and 15 or less. The number ( _N13c) of fibers having the change point 18 in the constituent fibers constituting the side region 13c is preferably 5 or more and 20 or less, more preferably 10 or more and 20 or less. The method for measuring the number of fibers having the change point 18 is as follows.

[Method of Measuring Number of Fibers Having Change Points 18 in Constituent Fibers Forming Top Area 13a, Bottom Area 13b, or Side Area 13c]
Regarding the number of fibers having the changing points 18 in the constituent fibers 11 constituting the top region 13a, the scanning electron beam is located near the top of the top region 13a, which is the upper portion when the thickness T of the nonwoven fabric is divided into three equal parts in the Z direction. Using a microscope, magnify and observe (adjusted to a magnification that can measure about 30 to 60 fiber cross-sections; 50 to 500 times), and randomly extract 20 constituent fibers 11 constituting the top region 13a, and obtain 20 constituent fibers The number of fibers having a change point 18 in 11 is counted. This is defined as the number of fibers having a change point 18 in the constituent fibers constituting the top region 13a. The measurement is performed at three places, and the average is defined as the number of fibers having a change point 18 in the constituent fibers constituting the top region 13a of the sample. Similarly, regarding the number of fibers having the changing points 18 in the constituent fibers 11 constituting the bottom region 13b, the vicinity of the bottom point of the bottom region 13b, which is a lower portion when the thickness of the nonwoven fabric is divided into three equal parts in the Z direction. Measure and determine. Similarly, the number of fibers having the changing point 18 in the constituent fibers 11 constituting the side region 13c is determined by measuring the central portion when the thickness of the nonwoven fabric is divided into three equal parts in the Z direction. In addition, JCM-5100 (trade name) manufactured by JEOL Ltd. is used as the scanning electron microscope.

The basis weight of the nonwoven fabric 1 is preferably 15 g / ^{m 2} or more 50 g / ^{m 2} or less the average value of the entire sheet, 20 g / ^{m 2} or more 40 g / ^{m 2} or less is more preferable.

  Further, a small amount of a fiber treatment agent such as a fiber colorant, an antistatic property agent, a lubricant, or a hydrophilic agent may be attached to the surface of the constituent fibers 11 of the nonwoven fabric 1 at the stage of the raw material.

  As a method for attaching the fiber treating agent to the surface of the constituent fibers 11, various known methods can be employed without particular limitation. For example, application by spraying, application by a slot coater, application by roll transfer, immersion in a fiber treatment agent and the like can be mentioned. These treatments may be performed on the fibers before web formation, or may be performed after the fibers are formed into webs by various methods. However, the processing needs to be performed before the hot air blowing processing described later. The fiber with the fiber treatment agent attached to the surface is dried at a temperature sufficiently lower than the melting point of the polyethylene resin (for example, 120 ° C. or lower) by, for example, a hot-air blow dryer.

  It is preferable that the space between the top sheet 2 and the absorber 4 and the space between the absorber 4 and the back sheet 3 are respectively bonded with an adhesive. When the members are joined with an adhesive, solid coating with a slot coater or the like may be used, but pattern coating is preferable. Preferable examples of the coating pattern for pattern coating include a spiral pattern, a dot pattern, a stripe pattern (striped pattern), a lattice pattern, and a checkerboard pattern.

The above-mentioned top sheet 2 provided with the nonwoven fabric 1 and the lower sheet 6 is a fusion step in which the intersections of the constituent fibers of the fibrous web containing the high elongation fibers are fusion-bonded at the fusion portion to form a fiber sheet. And a stretching step of stretching the fiber sheet in one direction, a compounding step of joining the lower sheet 6 to the nonwoven fabric, and a part of the lower sheet in the back space of the ridge portion formed in the upper nonwoven fabric. It is manufactured by an introduction process to be introduced.
The manufacturing process of the topsheet 2 will be described with reference to FIGS. FIG. 7 schematically shows a preferred manufacturing apparatus 100 used in the method for manufacturing the topsheet 2. The manufacturing apparatus 100 is suitably used for manufacturing an air-through nonwoven fabric and manufacturing a topsheet using the same. The manufacturing apparatus 100 includes a web forming unit 200, a hot-air processing unit 300, an extending unit 400, and a lower sheet joining unit 500 in this order from the upstream side to the downstream side of the manufacturing process.

  As shown in FIG. 7, the web forming unit 200 includes a web forming apparatus 201. As the web forming apparatus 201, a card machine is used. As the card machine, a card machine which is generally used in the technical field of absorbent articles can be used without any particular limitation. Depending on the specific use of the nonwoven fabric 1, another web manufacturing apparatus, for example, an air laid apparatus, can be used instead of the card machine.

  The hot air processing unit 300 includes a hood 301 as shown in FIG. Inside the hood 301, hot air can be blown by an air-through method. Further, the hot-air treatment unit 300 includes an endless conveyor belt 302 made of a gas permeable net. The conveyor belt 302 goes around the hood 301. The conveyor belt 302 is formed of a resin such as polyethylene terephthalate or a metal.

  The temperature of the hot air blown in the hood 301 and the heat treatment time are preferably adjusted so that the intersections of the high elongation fibers included in the constituent fibers 11 of the fiber web 1b are thermally fused. More specifically, the temperature of the hot air is preferably adjusted to a temperature higher by 0 ° C. to 30 ° C. than the melting point of the resin having the lowest melting point in the constituent fibers 11 of the fiber web 1b. The heat treatment time is preferably adjusted to 1 to 5 seconds according to the temperature of the hot air. In addition, from the viewpoint of promoting further entanglement between the constituent fibers 11, the wind speed of the hot air is preferably about 0.3 m / sec to 1.5 m / sec. Further, the transport speed is preferably about 5 m / min to 100 m / min.

  As shown in FIGS. 7 and 8, the extending section 400 includes a pair of concave and convex rolls 401 and 402 that can mesh with each other. The pair of concave and convex rolls 401 and 402 are formed so as to be heatable, and large diameter convex portions 403 and 404 and small diameter concave portions (not shown) are alternately arranged in the roll axis direction. The concavo-convex rolls 401 and 402 may or may not be heated, but the heating temperature when heating the concavo-convex rolls 401 and 402 makes it easy to stretch the high elongation fibers included in the constituent fibers 11 of the fiber sheet 1a described later. From the viewpoint, it is preferable that the temperature be equal to or higher than the glass transition point of the resin having the highest glass transition point in the high elongation fiber and equal to or lower than the melting point of the resin having the lowest melting point in the high elongation fiber. More preferably at a temperature of at least 10 ° C. higher than the glass transition point of the fiber and at a temperature of 10 ° C. lower than the melting point, still more preferably at a temperature of at least 20 ° C. higher than the glass transition point of the fiber and at a temperature of 20 ° C. lower than the melting point. is there. For example, when heating is performed when PET (core) having a glass transition point of 67 ° C. and a melting point of 258 ° C./glass transition point of −20 ° C. and a melting point of 135 ° C. is used as the fiber having a core / sheath structure. In this case, the temperature is preferably from 67 ° C to 135 ° C, more preferably from 77 ° C to 125 ° C, even more preferably from 87 ° C to 115 ° C.

  Further, in the manufacturing apparatus 100, as shown in FIG. 8, the interval (pitch) between the large-diameter convex portions 403, 403 adjacent to each other in the roll axis direction of the concave-convex roll 401, and the adjacent convex portions in the roll axis direction of the concave-convex roll 402. The interval (pitch) between the large-diameter convex portions 404, 404 is the same interval (pitch) w, and the interval (pitch) w is such that the high elongation fibers included in the constituent fibers 11 of the fiber sheet 1a are successfully formed in the drawing device. When stretched, the point of change from the small-diameter portion to the large-diameter portion described above is adjacent to the fused portion, and from the viewpoint of improving the feel, preferably 1 mm or more and 10 mm or less, particularly preferably 1.5 mm or more. 8 mm or less. From a similar point of view, as shown in FIG. 8, the pressing amount t of the pair of concave and convex rolls 401 and 402 (the distance between the apex of the large-diameter convex portion 403 and the apex of the large-diameter convex portion 404 adjacent to each other in the roll axis direction) is It is preferably from 1.1 mm to 12 mm, and particularly preferably from 1.5 mm to 9 mm. From the same viewpoint, the mechanical stretching ratio is preferably 2 times or more and 12 times or less, and particularly preferably 2.4 times or more and 10 times or less.

  The lower sheet joining portion 500 includes an uneven roll 402 and a flat roll 501 having a smooth surface, and has an uneven shape between the large-diameter convex portion 404 of the uneven roll 402 and the peripheral surface of the flat roll 501. The nonwoven fabric 1 and the lower sheet 6 are joined by heating and pressing.

  When performing the above-described first method, a second hot-air processing unit (not shown) having a configuration similar to that of the above-described hot-air processing unit 300 is disposed downstream of the lower sheet joining unit 500.

A method (first method) of manufacturing the topsheet 2 using the manufacturing apparatus 100 having the above configuration will be described.
First, as shown in FIG. 7, in a web forming unit 200, a short fiber-like constituent fiber 11 having a heat-extensible conjugate fiber which is a high elongation fiber is used as a raw material, and a web forming apparatus 201 which is a card machine is used. The fiber web 1b is formed (web forming step). The fiber web 1b manufactured by the web forming apparatus 201 is in a state in which the constituent fibers 11 are loosely entangled with each other, and has not yet achieved the shape retention as a sheet.

  Next, as shown in FIG. 7, the intersection of the constituent fibers 11 of the fiber web 1b containing the high elongation fiber is heat-sealed at the fusion part 12 to form the fiber sheet 1a (fusion step). Specifically, the fiber web 1b is conveyed on a conveyor belt 302, and hot air is blown by the hot air processing unit 300 while passing through the hood 301 by an air-through method. When the hot air is blown by the air-through method in this manner, the constituent fibers 11 of the fiber web 1b are further entangled with each other, and at the same time, the intersections of the entangled fibers are heat-fused (see FIG. 9A) to form a sheet. The fiber sheet 1a having shape retention is manufactured.

  Next, as shown in FIG. 8, the fused fiber sheet 1a is stretched in one direction (stretching step). Specifically, the fused fiber sheet 1a having shape retaining properties as a sheet is transported between a pair of concave and convex rolls 401 and 402, and as shown in FIGS. 9 (a) to 9 (c). Then, the fiber sheet 1a is stretched, and one component fiber 11 between the adjacent fusion parts 12 and 12 has a large fiber diameter sandwiched between two small diameter parts 16 and 16 having a small fiber diameter. The large diameter portion 17 is formed, and the change point 18 from the small diameter portion 16 to the large diameter portion 17 is set to be 1/3 of the interval T between the fused portions 12 adjacent to the fused portion 12. Form within the range. More specifically, as shown in FIG. 9A, a fiber sheet 1 a where the intersections of the constituent fibers 11 are heat-sealed at the fusion part 12 is conveyed between a pair of uneven rolls 401 and 402. Then, the fiber sheet 1a is stretched in the orthogonal direction (CD, roll axis direction) orthogonal to the machine direction (MD, flow direction). When the fiber sheet 1a is stretched in the orthogonal direction (CD, roll axis direction), as shown in FIG. 9A, a space between the adjacent fused portions 12, 12 fixing the constituent fibers 11 together. Is positively stretched in the orthogonal direction (CD, roll axis direction). In particular, as shown in FIG. 9 (b), local shrinkage is likely to occur first in the vicinity of the fusion parts 12 fixing the constituent fibers 11, and the distance between the fusion parts 12 adjacent to each other is small. Regarding the constituent fiber 11 of the book, two small diameter portions 16, 16 are formed at both ends, and a portion sandwiched between the two small diameter portions 16, 16 becomes a large diameter portion 17, and the two small diameter portions 16, 16 are formed. A large-diameter portion 17 sandwiched between the two is formed. As described above, since local contraction is likely to occur first in the vicinity of each of the fused portions 12, the transition point 18 from the small-diameter portion 16 to the large-diameter portion 17 corresponds to the fusion portion 12, which is adjacent to the fused portion 12. They are formed in a range of 1/3 of the interval T between the twelve.

  As shown in FIG. 9 (c), with respect to one constituent fiber 11 between some of the fused portions 12, 12, there is further room for expansion (expansion margin). It is stretched in the orthogonal direction (CD, roll axis direction), the large-diameter portion 17 between the adjacent fused portions 12, 12 is extended, and a plurality of small-diameter portions 16 are formed in the large-diameter portion 17. become.

  In the stretching step, the small-diameter portion 16 and the large-diameter portion 17 are formed from the high elongation fiber at the same time as the large-diameter convex portion 403 of the concave-convex roll 401 and the large-diameter convex portion of the concave-convex roll 401 in the fiber sheet 1a. A portion located between the portion 404 and the portion 404 is stretched more than other portions. In this case, since the constituent fibers of the fiber sheet 1a are high elongation fibers, the fibers are not cut even when subjected to stretching, and the stretching is successfully performed. In the fiber sheet 1 a, a portion located between the large-diameter convex portion 403 of the concave-convex roll 401 and the large-diameter convex portion 404 of the concave-convex roll 401 is a side region 13 c of the convex portion 13 in the target nonwoven fabric 1. Therefore, the inter-fiber distance is increased in the side region 13c by the above-mentioned stretching without cutting the fibers as compared with before the stretching. As a result, the fiber density of the side region 13c is lower than that of the other region, the ridge 13 is easily deformed in the side region 13c, and the followability of the top region 13a to the wearer's skin is improved. . In addition, since the fibers constituting the side region 13c are not cut, the strength of the ridge 13 is maintained at a high level. As a result, even if a load is applied to the ridge 13, the ridge 13 is less likely to be crushed.

  As described above, according to the method for manufacturing the topsheet 2 using the manufacturing apparatus 100, the nonwoven fabric 1 including the constituent fibers 11 shown in FIG. 6 can be continuously and efficiently manufactured. In addition, the manufactured nonwoven fabric 1 is conveyed to the sheet joining portion of the lower sheet joining portion 500 while being deformed into an uneven shape by the uneven roll 402. A band-shaped lower sheet 6 used as a lower sheet unwound from a roll-shaped roll 6 ′ is supplied to the sheet confluence portion. And is introduced between the uneven roll 402 and the flat roll 501. In the first method, a laminated sheet having an upper fiber layer 61 and a lower fiber layer 62 shown in FIG. Between the concavo-convex roll 402 and the flat roll 501, the concave ridge portion of the concavo-convex nonwoven fabric 1 and the band-shaped lower sheet 6 are in contact with the large-diameter convex portion 404 of the concavo-convex roll 402 and the peripheral surface of the flat roll 501. Are heated and pressed to join them together (compositing step).

  Thereby, a top sheet manufacturing intermediate 2 'as shown in FIG. 5A is obtained. The surface sheet production intermediate 2 ′ has a configuration in which the nonwoven fabric 1 having an uneven structure is joined to the lower sheet 6 at the concave ridges 14. Then, when the topsheet manufacturing intermediate 2 ′ is heat-treated by the second hot-air processing unit (not shown), the lower fiber layer 62 in the lower sheet 6 thermally contracts, and as shown in FIG. As described above, the interval P3 between the ridges 13 in the nonwoven fabric 1 is reduced, and the upper fiber layer 61 side of the lower sheet 6 projects in the space direction on the back side of the ridges 13 to form the ridge inner portion 60 (introduction step). ).

  It is preferable that the temperature of the heat treatment by the second hot-air processing unit is higher than the shrinkage start temperature of the heat-shrinkable fibers included in the lower fiber layer 62 and lower than the heating temperature when the uneven rolls 401 and 402 are heated. The heat treatment in the second hot-air treatment unit may be a hot-air treatment for penetrating or blowing hot air, or a treatment for bringing a heating roll into contact with the lower fiber layer 62 of the lower sheet 6. good. In this way, the belt-shaped topsheet 2 having the form shown in FIG. 3 or FIG. 5B is obtained. After being wound, the belt-shaped topsheet 2 is introduced into a production line of the incontinence pad 10 or is introduced into a production line of the incontinence pad 10 without winding.

  As a method of manufacturing the top sheet 2, instead of the first method using the lower sheet 6 containing heat-shrinkable fibers, a second method using the lower sheet 6 containing heat-extensible fibers, a lower sheet joining portion 500 A third method using a raised sheet as the lower sheet 6 to be introduced into the lower sheet 6, a nonwoven fabric or a fiber web whose bulk and thickness have been increased by hot air treatment as the lower sheet 6 to be introduced into the lower sheet joint 500. The fourth method or the like used can also be used.

  In the second method, for example, a laminated sheet having an upper fiber layer 61 and a lower fiber layer 62 as a belt-shaped lower sheet 6 (see FIG. 5A), and fibers are heated on the upper fiber layer 61 by heating. The lower fiber layer 62 includes non-heat-extensible fibers that include heat-extensible fibers extending in the longitudinal direction. Then, the nonwoven fabric 1 provided with the concavo-convex structure by the stretching process and the lower sheet 6 are joined at the bottom of the concave streak portion of the nonwoven fabric 1, and a surface sheet manufacturing intermediate 2 ′ as shown in FIG. After that, the surface sheet production intermediate 2 ′ is heat-treated, and the upper fiber layer 61 containing the heat-extensible fiber is made to protrude in the space direction on the back side of the ridge 13 to have the ridge inner portion 60. The ridge 13 is formed. Thereby, the top sheet 2 in which a part of the lower sheet 6 has entered the space on the back side of the ridge 13 can be obtained. As the heat-extensible fiber, for example, those described in JP-A-2010-150686 can be used.

In the third method, a single-layered or multi-layered nonwoven fabric whose surface facing the nonwoven fabric 1 is raised as a belt-shaped lower sheet 6 into the lower sheet joining portion 500 by various known methods, and a stretching step is performed. Then, the nonwoven fabric 1 having the concavo-convex structure and the lower sheet 6 are joined at the bottom of the concave portion of the nonwoven fabric 1. As a result, a top sheet in which the raised surface or raised hair of the lower sheet 6 has entered the space on the back side of the ridge 13 can be obtained. Examples of the nonwoven fabric that is raised and used as the lower sheet include a spunbond nonwoven fabric, a meltblown nonwoven fabric, and a multilayer nonwoven fabric made of a laminate of these. In addition, an air-through nonwoven fabric, a heat-rolled nonwoven fabric, a heat-embossed nonwoven fabric, a spunlace nonwoven fabric, a needle-punched nonwoven fabric, a resin-bonded nonwoven fabric, and the like can also be used.
As a method of raising the brush, there is a method of rubbing the surface of the nonwoven fabric with a roller having an uneven surface, but the method is not limited to such a method.

  In the fourth method, for example, a single-layer or multi-layer nonwoven fabric, a fiber web, a laminated sheet thereof, or the like, whose bulk has been recovered by heat treatment of an air-through method for penetrating hot air, is used as a belt-shaped lower sheet 6 to form a lower sheet joint. Then, the nonwoven fabric 1 provided with the uneven structure in the stretching process and the lower sheet 6 thereof are joined at the bottom of the concave streak portion of the nonwoven fabric 1. Thereby, a top sheet in which a part of the lower sheet 6 has entered the space on the back side of the ridge 13 can be obtained.

FIG. 10 shows a diagram corresponding to FIG. 2A of the incontinence pad 10A according to the second embodiment of the present invention. The topsheet 2A of the incontinence pad 10A includes a nonwoven fabric 1 (upper nonwoven fabric) having the same configuration as the nonwoven fabric 1 of the incontinence pad 10, and a lower sheet 6A having a multilayer structure of two or more layers. The lower sheet 6A includes a first sheet 64 having lower protruding ridges 65 and lower recessed ridges 66 extending in the longitudinal direction X alternately in the width direction Y, and a second sheet 67 having a flat shape. . The ridges 13 on the topsheet 2A of the incontinence pad 10A also have a hollow structure, and the height H is greater than the interval P3 between the ridges 13 in the width direction Y. In addition, the lower ridge 65 of the first sheet 64, which is a part of the lower sheet 6A, enters the space on the back side of the ridge 13 of the nonwoven fabric 1A.
Therefore, according to the incontinence pad 10A of the second embodiment, the same effects as those of the incontinence pad 10 described above are exerted.

  The top sheet 2A in the second embodiment is formed by, for example, pressing or heating and pressing between uneven rolls to give a first sheet 64 having a three-dimensional shape with a cross-sectional waveform to a second sheet 67 at a lower layer concave streak portion 66 thereof. After joining to form a composite sheet, the composite sheet is introduced as a belt-shaped lower sheet 6A into the lower sheet joining section 500, and the nonwoven fabric 1 after the concavo-convex structure is imparted by a stretching process, and the lower sheet 6A at the bottom of the concave strip 14 of the nonwoven fabric 1.

In each of the above embodiments, the thickness of the absorber 4 is preferably 1 mm or more, more preferably 2 mm or more, and preferably 15 mm or less, more preferably 10 mm or less, and further preferably 1 mm or more and 15 mm or less. Preferably it is 2 mm or more and 10 mm or less.
The thickness of the absorber 4 is measured by the following method.
For the measurement of the thickness T, a Peacock-type precision measuring instrument (model R1-C) which is a micrometer having two parallel pressing surfaces (fixed pressing surface and movable pressing surface) is used. The measurement is performed at a pressure of 5 mm and a pressure of 100 kPa or less, and the size of the test piece for measurement is equal to or greater than the size of the following plate. A 20 mm × 20 mm plate (weight: 5.4 g) is placed on the test piece, the measuring element movable pressurizing surface is operated at a speed of 2 mm / s, applied to the plate, and the value immediately after stabilization is read. The pressure between the pressurized surfaces (the pressure applied to the test piece) is 1.3 kPa or less.

The absorbent article of the present invention is not limited to the above-described embodiment at all, and can be appropriately changed.
For example, the plan view shape of the joint portion 14s is not limited to a vertically long rectangular shape having long sides along the longitudinal direction X, and may be an arbitrary shape such as a square, a circle, a triangle, a quadrangle, and an ellipse. Further, as shown in FIG. 2B, the arrangement of the joints 14s is such that a joint row in which a plurality of joints 14s are intermittently arranged in series in the longitudinal direction X is formed in multiple rows in the width direction. However, the positions of the individual joints 14 s in the adjacent joint rows are not limited to the same position as shown in FIG. 2B, and may be shifted in the longitudinal direction X. For example, it may be shifted by a half pitch so as to form a staggered arrangement as a whole.
The lower sheet may have a single-layer structure or a multilayer structure of two or more layers. In addition, in both cases of a single layer and a multilayer, each layer may be a nonwoven fabric or a nonwoven fabric web.

  Further, the absorbent article of the present invention may be a sanitary napkin or a panty liner instead of the incontinence pad. Moreover, those absorbent articles may not have the leak-proof cuff 8. Further, a wing portion may be provided on both sides of the liquid excretion portion facing portion. Further, the length of the lower sheet 6 in one or both of the longitudinal direction X and the width direction Y of the absorbent article may be the same as or shorter than the nonwoven fabric 1 as the upper nonwoven fabric.

  Further, the absorber in the present invention may be composed of only an absorbent core and not having a core wrap sheet. For example, the absorber may be composed of only the absorbent core composed of the absorbent sheet 46 shown in FIG. The absorbent body shown in FIG. 11 is composed of a laminate in which two or more absorbent sheets 46 are laminated. The laminate of two or more layers may be a laminate in which one absorbent sheet is folded and the layers are adhered to each other, or a plurality of single-sheet absorbent sheets are laminated and laminated. It may be something. Further, an additional absorbent sheet may be arranged between layers of one or more layers of the laminate of two or more layers to form a partly thick absorber. As the absorbent sheet, an absorbent sheet containing a fiber material and a water-absorbing polymer is preferably used. Further, as the absorbent sheet, the bonding between the constituent fibers or between the constituent fibers and the water-absorbing polymer via the adhesive force generated in the water-absorbing polymer in the wet state or a binder such as an adhesive or an adhesive fiber added separately. And the like can be preferably used. As an absorbent sheet, an absorbent sheet manufactured by the method described in JP-A-8-246395, a pulverized pulp supplied in an air stream and a water-absorbing polymer are deposited, and then an adhesive (eg, vinyl acetate) is deposited. Sheet, hardened with PVA, etc.), absorbent sheet obtained by applying a hot-melt adhesive between paper and non-woven fabric and then spraying a super absorbent polymer, spun bond or melt blown non-woven fabric An absorbent sheet or the like obtained by blending a superabsorbent polymer during the process can also be used. These absorbent sheets can be used as a single-layered absorber without laminating two or more layers. In the case of stacking, the layers do not need to be bonded.

10,10A Incontinence pad (absorbent article)
1a Fiber sheet 1b Fiber web 2, 2A Surface sheet 1 Non-woven fabric (upper layer non-woven fabric)
DESCRIPTION OF SYMBOLS 11 Constituent fiber 12 Fused part 13 Convex part 14, 14A Concave part 14s Joining part 16 Small diameter part 17 Large diameter part 6 Lower sheet 60 Inside part of convex part (part which entered into space behind convex part)
REFERENCE SIGNS LIST 3 back sheet 4 absorber 40 absorbent core 41 high basis weight portion 42 low basis weight portion 43 longitudinal groove 45 core wrap sheet 8 leakproof cuff 100 manufacturing apparatus 200 web forming section 201 web forming apparatus 300 hot air processing section 400 stretching section 401 , 402 Concavo-convex roll 403,404 Large-diameter convex portion 500 Lower sheet joining portion 501 Flat roll

Claims (5)

A liquid-permeable top sheet forming a skin contact surface, a back sheet forming a non-skin contact surface, and an absorbent article interposed between the two sheets, and having an absorbent article having a longitudinal direction and a width direction. So,
The topsheet is an upper nonwoven fabric having an uneven structure in which the ridges and recesses extending in the longitudinal direction are alternately formed in the width direction, and the upper nonwoven fabric at a joint formed at the bottom of the recess. And a lower sheet joined thereto, wherein the ridge has a hollow structure,
The upper layer nonwoven fabric has a fiber density in a side region forming a side wall portion of the ridge portion, a fiber density in a top region forming a top portion of the ridge portion and a bottom region forming a bottom portion of the concave ridge portion. Lower than the fiber density,
The height H of the convex portion is much larger than the interval P3 of the convex portion in the width direction,
The plurality of ridges constituting the uneven structure are uniform in height,
The surface of the lower sheet on the absorber side is flat,
Part of the lower sheet enters the space on the back side of the ridge, and the maximum height h6 of the portion entering the space is 、 of the height H of the ridge. Not less than 2/3,
The absorbent article, wherein the portion of the lower sheet that enters the space has a solid structure .   2. The absorbent article according to claim 1, wherein the height H of the ridge is 1.1 times or more and 5 times or less of the interval P3 between the ridges. 3. The lower sheet is formed from a fiber aggregate, fiber density of the portion enters in the space it is higher than the fiber density of the side region of the upper layer nonwoven fabric, according to claim 1 or 2 Absorbent articles. The absorption according to any one of claims 1 to 3, wherein the maximum height of the portion entering the space is not less than 1/3 and not more than 2/3 of the height H of the ridge. Products. The absorbent article according to any one of claims 1 to 4 , wherein the upper nonwoven fabric includes a fiber having a large diameter portion and a small diameter portion having different fiber diameters in the side region.

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