Absorbent articles

Abstract

The present invention provides an absorbent article having a second sheet, wherein the surface of the second sheet on the top sheet side can be made whiter, thereby improving the appearance of the absorbent article when viewed from the skin side. [Solution] An absorbent article 1 having a top sheet 2, a back sheet 3, and an absorbent 4 disposed between them, with a second sheet 10 disposed between the top sheet 2 and the absorbent 4, wherein the second sheet 10 is composed of a laminate having a nonwoven fabric layer 11 and a plastic film layer 12 from the top sheet 2 side, a plurality of through holes are formed in the second sheet 10, the nonwoven fabric layer 11 is composed of spunbond nonwoven fabric, the melting point of the constituent fibers of the nonwoven fabric layer 11 is higher than the melting point of the plastic film layer 12, the plastic film layer 12 is bonded to the nonwoven fabric layer 11, and the whiteness of the surface of the second sheet 10 on the top sheet 2 side is 76% or more.

Description

[Technical Field]

[0001] This invention relates to absorbent articles such as disposable diapers, urine pads (including incontinence pads), and sanitary napkins. [Background technology]

[0002] Conventionally, absorbent articles are known that have a top sheet, a back sheet, and an absorbent material disposed between them, with a second sheet disposed between the top sheet and the absorbent material. The second sheet is provided to enhance the absorption performance of urine and other substances in the absorbent article, and various types of second sheets are known. For example, Patent Document 1 discloses an absorbent article having a second sheet which is composed of a laminate having a nonwoven fabric layer and a plastic film layer from the top sheet side and has a plurality of through holes formed thereon. Patent Document 2 discloses an absorbent article having a composite surface sheet which has a plurality of holes formed in a laminate sheet having a nonwoven fabric and a film from the top sheet side. Patent Document 3 discloses the use of a three-dimensional perforated sheet made of a composite sheet laminated with a nonwoven fabric and a film as the second sheet of an absorbent article. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-019616 [Patent Document 2] Special Publication No. 2005-511171 [Patent Document 3] Japanese Patent Publication No. 2007-167212 [Overview of the project] [Problems that the invention aims to solve]

[0004] Since absorbent materials are used in contact with the skin, it is desirable that they appear clean and presentable. For example, it is desirable that absorbent materials appear as white as possible when viewed from the skin-facing side, thereby improving their appearance. Furthermore, this design enhances the visibility of the skin-facing surface of the absorbent material even in dark places, making it easier to properly wear the absorbent material.

[0005] The present invention has been made in view of the above circumstances, and its object is to provide an absorbent article having a second sheet, wherein the surface of the second sheet on the top sheet side can be made whiter, thereby improving the appearance of the absorbent article when viewed from the skin side. [Means for solving the problem]

[0006] The absorbent article of the present invention that has been able to solve the above-mentioned problems is as follows. [1] An absorbent article having a top sheet, a back sheet, and an absorbent material disposed between them, wherein a second sheet is disposed between the top sheet and the absorbent material, The second sheet is composed of a laminate having a nonwoven fabric layer and a plastic film layer from the top sheet side, and a plurality of through holes are formed in the second sheet. The aforementioned nonwoven fabric layer is composed of spunbond nonwoven fabric. The melting point of the constituent fibers of the nonwoven fabric layer is higher than that of the plastic film layer, and the plastic film layer is bonded to the nonwoven fabric layer. An absorbent article in which the whiteness of the surface on the top sheet side of the second sheet is 76% or higher. [2] The absorbent article according to [1], wherein the mass per unit area of ​​the nonwoven fabric layer is less than the mass per unit area of ​​the plastic film layer. [3] The absorbent article according to [1] or [2], wherein both the constituent fibers of the nonwoven fabric layer and the plastic film layer are made of polyolefin resin. [4] The absorbent article according to any one of [1] to [3], wherein the plastic film layer contains a high-density polyethylene resin. [5] The absorbent article according to any one of [1] to [4], wherein the area ratio of the through holes in the second sheet is 1% or more and 10% or less. [6] The absorbent article according to any one of [1] to [5], wherein the second sheet has a protruding portion that protrudes toward the back sheet side along the outer edge of the through hole, and the height of the protruding portion is 0.1 times or more and 0.5 times or less the separation distance between adjacent protruding portions. [7] The absorbent article according to any one of [1] to [6], wherein the second sheet has a protruding portion that protrudes toward the back sheet side along the outer edge of the through hole, and in the cross section in the thickness direction of the second sheet, the ratio S2 / S1 of the area S1 of a rectangle having the separation distance between adjacent protruding portions as the long side and the height of the protruding portion as the short side, and the area S2 of the non-existing portion of the second sheet between adjacent protruding portions in the region surrounded by the rectangle is 3 / 4 or more. [8] The absorbent article according to any one of [1] to [7], wherein the non-woven fabric layer penetrates into the through holes of the second sheet. [9] The absorbent article according to any one of [1] to [8], wherein in a plan view of the absorbent article, the entire second sheet is located inward of the outer edge of the absorber.

[10] The absorbent article according to any one of [1] to [9], wherein the plastic film layer is separably joined to the non-woven fabric layer in the second sheet. [Effect of the Invention]

[0007] The absorbent article of the present invention can form the surface on the topsheet side of the second sheet whiter, and can improve the appearance when the absorbent article is viewed from the skin side. [Brief Description of the Drawings]

[0008] [Figure 1] As an example of the absorbent article of the present invention, a plan view of a urine pad viewed from the topsheet side is shown. [Figure 2]Figure 1 shows an example of a II-II cross-section of an absorbent material. [Figure 3] Figures 1 and 2 show enlarged perspective views of the second seat provided in the absorbent material. [Figure 4] This shows an example of a cross-sectional view around a through-hole in the thickness direction of the second seat. [Figure 5] This shows another example of a cross-sectional view around a through-hole in the thickness direction of the second seat. [Modes for carrying out the invention]

[0009] The absorbent article of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments shown in the drawings. Figures 1 to 5 show an example of the structure of a urine pad as an example of the absorbent article of the present invention. Figure 1 is a plan view of the absorbent article (urine pad) as seen from the top sheet side, and Figure 2 is an example of a II-II cross-section of the absorbent article shown in Figure 1. Figure 3 is an enlarged perspective view of the second sheet provided in the absorbent article shown in Figures 1 and 2, and Figures 4 and 5 are examples of cross-sectional views around the through-hole in the thickness direction of the second sheet. In the drawings, arrow x represents the width direction, arrow y represents the longitudinal direction, and the direction perpendicular to the plane formed by arrows x and y represents the thickness direction z. However, the absorbent article of the present invention is not limited to the embodiments shown in the drawings.

[0010] The absorbent article 1 has a top sheet 2, a back sheet 3, and an absorbent material 4 placed between them, with a second sheet 10 placed between the top sheet 2 and the absorbent material 4. The absorbent article 1 can be used, for example, in disposable diapers, urine pads (including incontinence pads), sanitary napkins, etc.

[0011] The absorbent article 1 has a longitudinal direction y and a width direction x. The longitudinal direction y corresponds to the direction extending in the front-to-back direction between the wearer's legs when the absorbent article is worn by the wearer. The width direction x is the direction that lies on the same plane as the absorbent article and is perpendicular to the longitudinal direction y, and corresponds to the left-to-right direction of the wearer when the absorbent article is worn. Furthermore, the direction parallel to the plane formed by the longitudinal direction y and the width direction x is defined as the plane direction, and the direction perpendicular to it is defined as the thickness direction z.

[0012] The top sheet 2 is a sheet located on the wearer's side when the absorbent article is worn, and is preferably permeable to liquids. As the top sheet 2, for example, a nonwoven fabric made from hydrophilic fibers such as cellulose, rayon, or cotton; or a nonwoven fabric made from hydrophobic fibers such as polyolefin (e.g., polypropylene, polyethylene), polyester (e.g., PET), or polyamide (e.g., nylon), in which the surface of the hydrophobic fibers has been made hydrophilic with a hydrophilizing agent such as a surfactant can be used. In addition to the above nonwoven fabrics, woven fabrics, knitted fabrics, perforated plastic films, or combinations thereof may also be used as the top sheet 2.

[0013] The backsheet 3 is a sheet located on the opposite side from the wearer, i.e., the outside, when an absorbent article is worn, and is preferably impermeable to liquids. As the backsheet 3, a nonwoven fabric formed from hydrophobic fibers such as polyolefin (e.g., polypropylene, polyethylene), polyester (e.g., PET), or polyamide (e.g., nylon), or a plastic film can be used. Alternatively, a laminate of nonwoven fabric and plastic film may be used. In this invention, impermeability to liquids also includes water repellency.

[0014] The absorbent article 1 preferably has raised flaps 5 on both sides in the width direction x on the skin-facing side. By providing the raised flaps 5, lateral leakage of urine, etc., is prevented. The raised flaps 5 can be formed, for example, by joining side sheets 6 extending in the longitudinal direction y to both sides in the width direction x of the top sheet 2, and providing an elastic member 7 for standing up in the inner portion of the side sheet 6 in the width direction x. By providing the side sheet 6 and the elastic member 7 for standing up in this way, the contraction force of the elastic member 7 causes the inner portion of the side sheet 6 in the width direction x to stand up towards the wearer's skin, forming the raised flaps 5. The raised flaps 5 or side sheets 6 are preferably made of a liquid-impermeable plastic film or a liquid-impermeable nonwoven fabric.

[0015] The nonwoven fabrics used to make up each of the sheets described above include spunbond nonwoven fabric, point-bond nonwoven fabric, air-through nonwoven fabric, meltblown nonwoven fabric, airlaid nonwoven fabric, spunlace nonwoven fabric, SMS nonwoven fabric, etc. The mass per unit area of ​​each of these sheets is 8 g / m². 2 The above is preferable, 10 g / m 2 The above is more preferable, and also 40g / m 2 The following is preferable: 30 g / m 2 The following are preferable.

[0016] The absorbent body 4 is not particularly limited as long as it contains an absorbent material capable of absorbing excrement such as urine. As the absorbent body 4, for example, a molded body formed by molding an absorbent material into a predetermined shape can be used, or the molded body can be covered with a covering sheet such as a paper sheet (e.g., tissue paper or thin paper) or a liquid-permeable nonwoven fabric sheet. Examples of absorbent materials include hydrophilic fibers such as pulp fibers, and superabsorbent resins such as polyacrylic acid, polyaspartic acid, cellulose, and starch-acrylonitrile. The superabsorbent material may also include polyolefin fibers such as polyethylene and polypropylene, and heat-fusible fibers such as polyester fibers such as PET and polyamide fibers. These heat-fusible fibers may be hydrophilized with surfactants or the like to increase their affinity for urine, etc.

[0017] The absorbent material preferably contains hydrophilic fibers to increase the absorption rate of urine and other fluids. Furthermore, the absorbent material preferably contains a water-absorbent resin to increase its absorption capacity. Therefore, the absorbent body 4 preferably contains hydrophilic fibers (especially pulp fibers) and a water-absorbent resin. In this case, for example, it is preferable to use a material in which a water-absorbent resin is mixed or scattered on an aggregate of hydrophilic fibers.

[0018] The absorbent material 4 may be a sheet-shaped absorbent material. Examples of sheet-shaped absorbent materials include those formed by having an absorbent resin between nonwoven fabrics and not having pulp fibers. Because such a sheet-shaped absorbent material has an absorbent resin between the nonwoven fabrics, it can achieve a high absorption capacity. Furthermore, because the sheet-shaped absorbent material does not have pulp fibers between the nonwoven fabrics, it can be formed into a thin, non-bulky form.

[0019] The absorbent material 4 may have multiple absorbent layers. For example, the absorbent material 4 may have a first absorbent layer on the second sheet 10 side and a second absorbent layer on the back sheet 3 side. The number of absorbent layers included in the absorbent material 4 can be appropriately determined depending on the application.

[0020] The shape (planar shape) of the absorbent 4 is not particularly limited. The shape of the absorbent 4 can be appropriately determined according to the application, and examples include a roughly rectangular shape, hourglass shape, gourd shape, shuttlecock shape, etc. If the absorbent 4 has multiple absorbent layers, the shapes (planar shapes) and / or sizes of the absorbent layers may differ from each other.

[0021] The second sheet 10 is a sheet placed between the top sheet 2 and the absorber 4. The second sheet 10 has a first surface 10A on the top sheet 2 side and a second surface 10B on the back sheet 3 side. As shown in Figure 3, the second sheet 10 is composed of a laminate having a nonwoven fabric layer 11 and a plastic film layer 12 from the top sheet 2 side, and a plurality of through holes 13 are formed in the second sheet 10. That is, the second sheet 10 is composed of a laminate of the nonwoven fabric layer 11 and the plastic film layer 12, with the nonwoven fabric layer 11 located on the top sheet 2 side and the plastic film layer 12 located on the back sheet 3 side, and the through holes 13 are formed to penetrate the second sheet 10 in the thickness direction z. The through holes 13 are formed to extend from the first surface 10A to the second surface 10B inside the second sheet 10.

[0022] In absorbent article 1, the second sheet 10 configured in this way is placed between the top sheet 2 and the absorbent core 4. This allows urine and other fluids excreted by the wearer and permeated through the top sheet 2 to be quickly drawn into the absorbent core 4, while also reducing the wettability of the top sheet 2. Specifically, because a nonwoven fabric layer 11 is present on the first surface 10A of the second sheet 10, the urine and other fluids absorbed by the top sheet 2 are drawn into the second sheet 10 by the nonwoven fabric layer 11. The urine and other fluids that have moved to the second sheet 10 can then pass through the through-holes 13 formed in the second sheet 10 and move to the absorbent core 4. On the other hand, the plastic film layer 12 of the second sheet 10 prevents the urine and other fluids that have moved to the absorbent core 4 from flowing back to the top sheet 2. As a result, absorbent article 1 has excellent urine absorption performance, and the wettability of the top sheet 2 is reduced, resulting in a comfortable wearing experience.

[0023] The second sheet 10 has a nonwoven fabric layer 11 made of spunbond nonwoven fabric, where the melting point of the constituent fibers of the nonwoven fabric layer 11 is higher than that of the plastic film layer 12, and the plastic film layer 12 is bonded to the nonwoven fabric layer 11. With the second sheet 10 constructed in this way, light entering from the first surface 10A side of the second sheet 10 is easily scattered by both the nonwoven fabric layer 11 and the plastic film layer 12, thereby increasing the whiteness of the first surface 10A of the second sheet 10. As a result, when the absorbent article 1 is viewed from the skin side, the whiteness of the second sheet 10 is more easily recognized through the top sheet 2, improving the appearance of the absorbent article 1. This will be explained in more detail below.

[0024] Spunbond nonwoven fabric is obtained by melting polymer raw materials, extruding them from a spinneret, stretching them, and accumulating them on a conveyor belt or the like to form a web. Therefore, spunbond nonwoven fabric has a certain size of fiber diameter, and the surface of the nonwoven fabric layer 11 is not perfectly smooth but is formed with some degree of unevenness. For example, while meltblown nonwoven fabric has a small fiber diameter and a relatively smooth surface, spunbond nonwoven fabric has a more uneven surface. The unevenness of the surface of spunbond nonwoven fabric originates from the external shape of the fibers that make up the nonwoven fabric, and is therefore formed as irregular fine irregularities. As a result, light entering from the first surface 10A of the second sheet 10 is easily scattered irregularly on the surface of the nonwoven fabric layer 11, increasing the whiteness. Also, because spunbond nonwoven fabric is formed from long fibers, there are no fine fibers sticking out, and shadows are less likely to form on the surface. Therefore, when light shines on the first surface 10A of the second seat 10, shadows are less likely to form, and from this point of view, the whiteness of the first surface 10A of the second seat 10 can be increased.

[0025] The second sheet 10 also tends to cause irregular light scattering on the surface of the plastic film layer 12. Since the melting point of the constituent fibers of the non-woven fabric layer 11 is higher than the melting point of the plastic film layer 12 and the plastic film layer 12 is joined to the non-woven fabric layer 11, when manufacturing the second sheet 10, the plastic film layer 12 is brought into a semi-molten state and overlaid on the non-woven fabric layer 11 composed of a spunbond non-woven fabric, so that the unevenness of the spunbond non-woven fabric surface can be shaped on the opposing surface of the plastic film layer 12 with the non-woven fabric layer 11. As a result, irregular fine unevenness is also formed on the surface of the plastic film layer 12 on the top sheet 2 side. Therefore, the light that passes through the non-woven fabric layer 11 and hits the plastic film layer 12 also tends to be irregularly scattered on the surface of the plastic film layer 12 on the top sheet 2 side.

[0026] In this way, in the absorbent article 1, the light entering from the first surface 10A side of the second sheet 10 tends to be irregularly scattered by both the non-woven fabric layer 11 and the plastic film layer 12, and it is difficult to form a shadow on the surface of the non-woven fabric layer 11. Therefore, the whiteness when the second sheet 10 is viewed from the first surface 10A side can be increased. Therefore, the appearance when the absorbent article 1 is viewed from the skin side can be improved.

[0027] The whiteness of the first surface 10A of the second sheet 10 is 76% or more. Thereby, the whiteness of the second sheet 10 can be made prominent. The whiteness of the first surface 10A of the second sheet 10 may be 78% or more. The upper limit of the whiteness is not particularly limited, and may be, for example, 94% or less, 90% or less, 88% or less, or 86% or less.

[0028] The whiteness (WL) is obtained by taking out the second sheet 10 from the absorbent article 1, placing it on a black plate, and using a spectrocolorimeter or a spectral densitometer to measure L * a * b * in the lightness (L * ) and chromaticity (a * , b *This can be determined by measuring the brightness (L). The whiteness measurement is performed on the part of the first surface 10A of the second sheet 10 other than the through hole 13. The black board has a brightness (L). * Use those with a value of less than 5. Whiteness (WL) is defined as lightness (L). * ) and chromaticity (a * ,b * From the value of ), we can calculate it using the following formula: WL = L * +3a * -3b * Chromaticity is a * The red direction, -a * Green direction, b * Yellow direction, -b * The blue direction is indicated. The whiteness is measured 5 times for each second sheet 10, and the average value is taken as the whiteness of the second sheet 10. Brightness (L * ) and chromaticity (a * ,b * Whiteness is measured, for example, using a Konica Minolta FD-7 fluorescence spectrophotometer (illumination: A light source, observation light source: D65). Whiteness can be determined by referring to JIS L 1916:2000.

[0029] The constituent fibers of the nonwoven fabric layer 11 and the constituent materials of the plastic film layer 12 are not particularly limited, as long as the melting point of the constituent fibers of the nonwoven fabric layer 11 is higher than the melting point of the plastic film layer 12. Preferably, the melting point of the constituent fibers of the nonwoven fabric layer 11 is 10°C or more higher than the melting point of the plastic film layer 12, more preferably 20°C or more higher, and even more preferably 30°C or more higher. This makes it easier to create surface irregularities of the nonwoven fabric layer 11 on the surface of the plastic film layer 12 without the nonwoven fabric layer 11 melting when the semi-molten plastic film layer 12 is layered on top of the nonwoven fabric layer 11. There is no particular upper limit to the difference in melting points between the constituent fibers of the nonwoven fabric layer 11 and the plastic film layer 12, and the difference may be 200°C or less, 150°C or less, or 100°C or less.

[0030] The spunbond nonwoven fabric constituting the nonwoven layer 11 can be made of synthetic resin fibers such as polyolefins (e.g., polypropylene, polyethylene), polyesters (e.g., PET), and polyamides (e.g., nylon), and it is preferable that the surface of the fibers is treated with a hydrophilizing agent such as a surfactant. By constructing the nonwoven layer 11 in this way, the penetration of urine and other substances into the interior of the fibers constituting the nonwoven fabric is suppressed. As a result, the amount of urine and other substances that remain on the top sheet 2 after moving from the top sheet 2 to the second sheet 10 is reduced, and more of the urine and other substances can easily pass through the through-holes 13 to the second sheet 10. It is preferable that the constituent fibers of the nonwoven layer 11 are made of thermoplastic resin.

[0031] The constituent fibers of the nonwoven fabric may consist of a single component or multiple components (i.e., composite fibers). When the constituent fibers of the nonwoven fabric consist of multiple components, it is preferable that the melting point of at least the component constituting the fiber surface is higher than the melting point of the plastic film layer 12, and it is more preferable that the melting points of all components are higher than the melting point of the plastic film layer 12.

[0032] The spunbond nonwoven fabric constituting the nonwoven layer 11 may be heat-embossed. Specifically, the spunbond nonwoven fabric of the nonwoven layer 11 may be heat-embossed on its own. If the spunbond nonwoven fabric of the nonwoven layer 11 is heat-embossed, it is possible to reduce the bulk of the nonwoven layer 11 while ensuring the urine-drawing effect of the nonwoven layer 11, thereby reducing the amount of urine that remains in the nonwoven layer 11. As a result, it is possible to reduce the amount of urine that flows back from the second sheet 10 to the top sheet 2.

[0033] In the nonwoven fabric layer 11, the shape and arrangement of the heat-embossed portions are not particularly limited, but it is preferable that the heat-embossed portions be provided in a scattered manner in any shape. The shape of each heat-embossed portion is not particularly limited, and can be circular, elliptical, oblong, polygonal, corrugated, star-shaped, etc., and these may be provided in a regular arrangement pattern or in a random arrangement pattern. When the heat-embossed portions are provided in a regular arrangement pattern, it is preferable that the heat-embossed portions be provided at each grid point of an arbitrary grid. The shape and arrangement of the heat-embossed portions are defined in a state in which no through holes 13 are formed.

[0034] The plastic film layer 12 can be a film formed from a synthetic resin such as polyolefin (e.g., polypropylene, polyethylene), polyester (e.g., PET), or polyamide (e.g., nylon), and it is preferable that the synthetic resin is a thermoplastic resin. The plastic film layer 12 may be treated with a hydrophilizing agent such as a surfactant.

[0035] Preferably, both the constituent fibers of the nonwoven fabric layer 11 and the plastic film layer 12 are made of polyolefin resin. This allows for the formation of lightweight nonwoven fabric layers 11 and plastic film layers 12 while ensuring the strength of both. Furthermore, since the constituent fibers of the nonwoven fabric layer 11 and the plastic film layer 12 are made of the same type of resin, the contact surface between the nonwoven fabric layer 11 and the plastic film layer 12 conforms well. Therefore, when a semi-molten plastic film layer 12 is placed on top of the nonwoven fabric layer 11, it becomes easier to bond the plastic film layer 12 to the nonwoven fabric layer 11 even if the nonwoven fabric layer 11 does not melt. In this case, for example, the constituent fibers of the nonwoven fabric layer 11 can be made of polypropylene resin, and the plastic film layer 12 can be made of polyethylene resin.

[0036] The plastic film layer 12 may contain high-density polyethylene resin. This allows the plastic film layer 12 to be formed in a milky white color, reducing its transparency and increasing the proportion of light that hits the plastic film layer 12 that is reflected or scattered on its surface rather than entering the interior of the plastic film layer 12. As a result, the whiteness of the second sheet 10 when viewed from the first surface 10A side can be increased. The plastic film layer 12 may be composed of high-density polyethylene resin. The density of the high-density polyethylene resin is 0.930 kg / m³ 3 A larger value is preferable, 0.936 kg / m 3 Larger than 0.940 kg / m 3 It may be larger. There is no particular upper limit to the density of high-density polyethylene resin, but 0.990 kg / m³ is not limited. 3 Below, 0.980kg / m 3 Below, 0.970kg / m 3 The following, or 0.960 kg / m 3 The following is also possible: The high-density polyethylene resin may be a homopolymer or a copolymer.

[0037] In bonding the nonwoven fabric layer 11 and the plastic film layer 12, it is preferable that the plastic film layer 12 is bonded to the nonwoven fabric layer 11 by partial melting. Furthermore, it is preferable that the nonwoven fabric layer 11 and the plastic film layer 12 are not bonded to each other by an adhesive. On the other hand, it is preferable that the nonwoven fabric layer 11 does not melt when bonding with the plastic film layer 12. This makes it possible to create the surface irregularities of the spunbond nonwoven fabric of the nonwoven fabric layer 11 on the surface of the plastic film layer 12 by layering the semi-molten plastic film layer 12 on top of the nonwoven fabric layer 11.

[0038] As described above, when the nonwoven fabric layer 11 and the plastic film layer 12 are joined, the plastic film layer 12 is detachably joined to the nonwoven fabric layer 11. That is, the nonwoven fabric layer 11 and the plastic film layer 12 are not mutually compatible, and as the surface of the plastic film layer 12 melts and solidifies, the surface of the plastic film layer 12 adheres to the surface of the nonwoven fabric layer 11, and the nonwoven fabric layer 11 and the plastic film layer 12 are joined to each other. In this case, the nonwoven fabric layer 11 and the plastic film layer 12 can be separated by pinching one with the right hand (or tweezers held in the right hand) and the other with the left hand (or tweezers held in the left hand) and peeling them apart. It is preferable that the nonwoven fabric layer 11 and the plastic film layer 12 are joined to each other in this detachably manner.

[0039] Preferably, the mass per unit area of ​​the nonwoven fabric layer 11 is smaller than the mass per unit area of ​​the plastic film layer 12. With the second sheet 10 configured in this way, when the semi-molten plastic film layer 12 is placed on top of the nonwoven fabric layer 11, it becomes easier to create the surface irregularities of the nonwoven fabric layer 11 on the surface of the plastic film layer 12. The plastic film layer 12 has a relatively large mass per unit area, making it easier to maintain its film shape even when semi-molten. On the other hand, the nonwoven fabric layer 11 has a relatively small mass per unit area, allowing it to be formed with a thin thickness, and when the plastic film layer 12 and the nonwoven fabric layer 11 are placed on top of each other, the nonwoven fabric layer 11 can be pressed deeply against the plastic film layer 12. This makes it possible to suitably create the surface irregularities of the nonwoven fabric layer 11 on the surface of the plastic film layer 12 when the semi-molten plastic film layer 12 is placed on top of the nonwoven fabric layer 11.

[0040] In a plan view of the absorbent article 1, it is preferable that the entire second sheet 10 is positioned inward from the outer edge of the absorbent body 4. When the second sheet 10 is positioned in this manner, the entire second sheet 10 will be located on the top sheet 2 side of the absorbent body 4 without protruding from it. Therefore, urine and other substances on the second sheet 10 can easily transfer through the through-holes 13 of the second sheet 10 to the top sheet 2 side surface of the absorbent body 4, preventing them from transferring to areas other than the absorbent body 4.

[0041] The through-hole 13 of the second sheet 10 will be described in detail. The planar shape of the through-hole 13 is not particularly limited and can be circular, elliptical, oblong, polygonal, irregular, etc. Preferably, the planar shape of the through-hole 13 has a certain length in different directions in the planar direction. For example, in a planar view of the second sheet 10 as seen from the first surface 10A side, the aspect ratio of the planar shape of the through-hole 13 is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. If the through-hole 13 is formed with such a planar shape, urine and the like can pass through the through-hole 13 more smoothly.

[0042] The planar shape of the through-hole 13 refers to the shape of the through-hole 13 in a plan view of the second sheet 10. The aspect ratio of the planar shape of the through-hole 13 can be determined by dividing the length in the major axis direction of the planar shape of the through-hole 13 by the length in the minor axis direction. The major axis direction of the planar shape of the through-hole 13 refers to the direction that gives the longest length of the planar shape of the through-hole 13. The minor axis direction refers to the direction perpendicular to the major axis direction, and the length in the minor axis direction of the planar shape of the through-hole 13 refers to the longest length in the minor axis direction of the planar shape of the through-hole 13. The planar shape of the through-hole 13 is determined based on the shape of the part of the through-hole 13 that is not visible from the second sheet 10 in a plan view of the second sheet 10 (i.e., the part that is visible on the other side of the second sheet 10).

[0043] The area ratio of the through-holes 13 in the second sheet 10 is preferably 1% or more and 10% or less. When the through-holes 13 are formed in this way, urine etc. that has moved onto the second sheet 10 can easily move smoothly through the through-holes 13 to the absorbent material 4. Also, when the through-holes 13 are not formed in an excessive area on the second sheet 10, the second sheet 10 will appear whiter when viewed from the top sheet 2 side. The area ratio of the through-holes 13 in the second sheet 10 is more preferably 2% or more, even more preferably 3% or more, even more preferably 8% or less, and even more preferably 6% or less.

[0044] The area ratio of the through-hole 13 in the second sheet 10 is calculated by dividing the area of ​​the through-hole 13 by the area of ​​the second sheet 10, with the area of ​​the second sheet 10 including the through-hole 13 as the numerator and the area of ​​the through-hole 13 as the denominator, when viewing the second sheet 10 from the first surface 10A side. The area of ​​the through-hole 13 is the area of ​​the part of the through-hole 13 that is not visible from the second sheet 10 (i.e., the part where the other side of the second sheet 10 is visible) when viewing the second sheet 10 from the first surface 10A side.

[0045] The area of ​​one through hole 13 is, for example, 0.04 mm². 2 The above is preferable, 0.1 mm 2 The above is more preferable, and also 3 mm 2 The following is preferable: 2 mm 2 The following is more preferable, 1 mm 2 The following is even more preferable: The length of the through hole 13 in the longitudinal direction, i.e., the maximum length of the through hole 13, is preferably 0.2 mm or more, more preferably 0.4 mm or more, preferably 2 mm or less, and more preferably 1 mm or less.

[0046] It is preferable that multiple through-holes 13 are arranged in a row in the planar direction of the second sheet 10. The spacing between adjacent through-holes 13 is preferably 0.5 mm or more, more preferably 0.8 mm or more, even more preferably 1 mm or more, and preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 4 mm or less.

[0047] It is preferable that the nonwoven fabric layer 11 penetrates the through-hole 13. That is, it is preferable that the nonwoven fabric layer 11 of the second sheet 10 is inserted into the through-hole 13 of the plastic film layer 12. If the through-hole 13 is formed in this way, the inner surface of the through-hole 13 is covered with nonwoven fabric, making it easier for urine, etc., to smoothly transfer from the nonwoven fabric layer 11 to the through-hole 13. As a result, it is easier for urine, etc., to smoothly transfer through the through-hole 13 to the absorbent material 4.

[0048] The spunbond nonwoven fabric of the nonwoven fabric layer 11 is heat-embossed, and each through-hole 13 may be formed with a smaller area than the heat-embossed portion. If heat-embossed portions are formed in this manner, the size of each heat-embossed portion will be larger, making it easier for urine, etc., to move on the first surface 10A of the second sheet 10, and as a result, urine, etc., will be more likely to collect in the through-holes 13.

[0049] As shown in Figure 4, it is preferable that the through-hole 13 in the second sheet 10 is formed to protrude toward the back sheet 3. That is, it is preferable that the second sheet 10 has a protruding portion 14 that protrudes toward the back sheet 3 along the outer edge of the through-hole 13. In the second sheet 10, the portion along the outer edge of the through-hole 13 (the peripheral portion of the through-hole 13) protrudes toward the back sheet 3, and the portion of the second sheet 10 that protrudes toward the back sheet 3 from the peripheral portion of the through-hole 13 becomes the protruding portion 14. Figure 4 shows a cross-sectional view of the second sheet 10 in the thickness direction z passing through the center 13C of the through-hole 13. The center 13C of the through-hole 13 refers to the centroid of the through-hole 13 in a plan view of the second sheet 10. If the protruding portion 14 is formed in this way, the tip of the protruding portion 14 will be more likely to come into contact with the surface of the absorbent material 4 on the top sheet 2 side. Therefore, urine etc. on the first surface 10A of the second sheet 10 will be more likely to smoothly transfer through the through-hole 13 to the absorbent material 4.

[0050] The protrusions 14 formed as described above also act to separate the second sheet 10 from the surface of the absorber 4 on the top sheet 2 side. As a result, the surface of the absorber 4 on the top sheet 2 side becomes less visible through the second sheet 10, and when the second sheet 10 is viewed from the top sheet 2 side, the second sheet 10 appears whiter.

[0051] In the cross-section of the second sheet 10 in the thickness direction z passing through the center 13C of the through hole 13, the height H (length in the thickness direction z) of the protrusion 14 is preferably 0.3 times or more the opening width W of the through hole 13, more preferably 0.4 times or more, even more preferably 0.5 times or more, and preferably 1.7 times or less, more preferably 1.5 times or less, and even more preferably 1.3 times or less. When the protrusion 14 is formed in this way, it is easier for the protrusion 14 to be held stably without being crushed, and the tip of the protrusion 14 is more likely to come into contact with the surface of the top sheet 2 side of the absorber 4. The opening width W of the through hole 13 refers to the narrowest length of the opening width (length in the vertical direction of the thickness direction z) of the through hole 13. In Figure 4, the opening width W is the width of the opening of the through hole 13 at the tip of the protrusion 14. If the planar shape of the through-hole 13 is not circular, the opening width W of the through-hole 13 is defined as the average of the opening width W in the cross-section along the long axis and the opening width W in the cross-section along the short axis of the planar shape of the through-hole 13.

[0052] The height H of the protrusion 14 is preferably 0.1 mm or more, more preferably 0.2 mm or more, preferably 1.0 mm or less, and more preferably 0.7 mm or less. When the protrusion 14 is formed in this manner, it is easier for the protrusion 14 to be held stably without being crushed, and the tip of the protrusion 14 is more likely to come into contact with the surface of the top sheet 2 side of the absorber 4.

[0053] In the cross-section of the second sheet 10 in the thickness direction z passing through the center 13C of the through hole 13, it is preferable that the edge 14E of the protrusion 14 is formed in a non-linear shape. If the edge 14E of the protrusion 14 is formed in this way, the tip of the protrusion 14 does not adhere closely to the surface of the absorbent body 4 on the top sheet 2 side, and a gap is easily formed between the tip of the protrusion 14 and the surface of the absorbent body 4 on the top sheet 2 side. Therefore, when the absorbent body 4 absorbs urine, etc. and its absorbency is saturated in the portion that overlaps with the through hole 13, the urine, etc. that entered the through hole 13 will not get stuck at the tip of the protrusion 14, but will easily spread to the surface of the absorbent body 4 on the top sheet 2 side through the gap between the tip of the protrusion 14 and the surface of the absorbent body 4 on the top sheet 2 side. As a result, even after the absorbent body 4 has absorbed urine, etc., urine, etc. will be able to move smoothly from the second sheet 10 to the absorbent body 4.

[0054] The projection 14 shown in Figure 4 is formed to extend toward the center 13C of the through hole 13 toward the back sheet 3. On the other hand, as shown in Figure 5, the projection 14 may have a projection base 14A and a projection end 14B, with the projection base 14A being formed to extend toward the center 13C of the through hole 13 toward the back sheet 3, and the projection end 14B being formed to extend toward the back sheet 3 away from the center 13C of the through hole 13. The projection base 14A is a part of the projection 14 that includes the starting point where the projection 14 protrudes toward the back sheet 3, and the projection end 14B is a part of the projection 14 that includes the tip of the projection 14 that protrudes toward the back sheet 3. Preferably, the projection 14 has a constricted portion between the projection base 14A and the projection end 14B where the cross-sectional area of ​​the through hole 13 is narrowed. In Figure 5, the boundary between the projection base 14A and the projection end 14B of the projection 14 is shown by a dotted line. With the formation of the protrusion 14 in this manner, urine and other fluids that have permeated the top sheet 2 and moved to the second sheet 10 can easily move smoothly to the absorbent material 4 through the through-hole 13. In other words, urine and other fluids on the first surface 10A of the second sheet 10 can easily move smoothly to the absorbent material 4 via the protrusion 14 that protrudes toward the back sheet 3. At this time, at the base of the protrusion 14A, urine and other fluids on the first surface 10A of the second sheet 10 tend to collect in the through-hole 13, and at the end of the protrusion 14B, the through-hole 13 is formed to widen toward the back sheet 3, so urine and other fluids are less likely to clog at the end of the protrusion 14B and can easily move smoothly to the absorbent material 4.

[0055] The protrusion 14 formed as described above also acts to separate the second sheet 10 from the surface of the absorber 4 on the top sheet 2 side. Since the protrusion 14 is formed such that the protruding end 14B extends away from the center 13C of the through hole 13 toward the back sheet 3 side, the protrusion 14 is more easily maintained in an upright position on the surface of the absorber 4 on the top sheet 2 side, and it is easier to secure the height of the protrusion 14. As a result, the part of the second sheet 10 other than the protrusion 14 is more easily positioned away from the surface of the absorber 4 on the top sheet 2 side, and it is easier to secure the distance between the first surface 10A of the second sheet 10 and the surface of the absorber 4 on the top sheet 2 side. Therefore, the surface of the absorber 4 on the top sheet 2 side is less visible through the second sheet 10, and when the second sheet 10 is viewed from the top sheet 2 side, the second sheet 10 appears whiter.

[0056] In a cross-section of the second sheet 10 in the thickness direction z passing through the center 13C of the through hole 13, it is preferable that the length H1 of the protruding base 14A in the height direction of the protruding portion 14 is longer than the length H2 of the protruding end 14B in the height direction of the protruding portion 14. If the protruding portion 14 is formed in this manner, it becomes possible to collect urine and other substances on the second sheet 10 into the through hole 13 more efficiently. Note that the length H1 of the protruding base 14A in the height direction of the protruding portion 14 means the length obtained by projecting the protruding base 14A in the height direction of the protruding portion 14. The same applies to the length H2 of the protruding end 14B in the height direction of the protruding portion 14.

[0057] The through-hole 13 shown in Figure 5 can be formed, for example, as follows: A laminate of a nonwoven fabric layer and a plastic film layer is inserted between a pin roll and an anvil roll having recesses on its surface. Numerous pins protrude from the surface of the pin roll, and numerous recesses corresponding to the pins are formed on the surface of the anvil roll. When the pin roll and anvil roll are rotated, the pins of the pin roll enter the recesses of the anvil roll. The pin has a straight body and a tip. The straight body has a constant outer diameter, while the tip has a decreasing outer diameter towards the tip, and the base end of the tip is formed to match the outer diameter of the straight body. When inserting the pin into the laminate of the nonwoven fabric layer and the plastic film layer, the pin is inserted up to the straight body. This allows the tip of the through-hole to be expanded. The anvil roll is configured to heat the inside of the recesses, and when the pin is inserted into the laminate of the nonwoven fabric layer and the plastic film layer, the area of ​​the plastic film layer near where the pin is inserted is heated. As a result, the plastic film layer in the vicinity shrinks due to heat, causing the tip of the through-hole to widen towards the tip, thereby forming the through-hole described above.

[0058] The height H of the protrusion 14 is preferably 0.1 times or more the separation distance between adjacent protrusions 14, more preferably 0.2 times or more, preferably 0.5 times or less, and more preferably 0.4 times or less. When the protrusion 14 is formed in this manner, it is easier for the protrusion 14 to be held stably without being crushed, and it is easier to ensure a sufficient distance between the first surface 10A of the second sheet 10 and the surface of the absorber 4 on the top sheet 2 side. As a result, when the second sheet 10 is viewed from the top sheet 2 side, the second sheet 10 appears whiter.

[0059] The separation distance between adjacent protrusions 14 is determined as follows: For each protrusion 14, the outer edge of the protrusion 14 at the position z in the thickness direction that gives the opening width W of the through hole 13 is defined as the outer shape of the protrusion 14. In a plan view of the second seat 10, the shortest distance between the outer shapes of one protrusion 14 and the protrusion 14 closest to it is defined as the separation distance between adjacent protrusions 14.

[0060] In a cross-section of the second sheet 10 in the thickness direction z, the ratio S2 / S1 of the area S1 of a rectangle R, where the distance between adjacent protrusions 14 is the longer side and the height of the protrusions 14 is the shorter side, to the area S2 of the area of ​​the second sheet 10 that is not present between adjacent protrusions 14 in the region enclosed by the rectangle R, is preferably 3 / 4 or more. In Figures 4 and 5, the rectangle R is shown by a dashed line. The area of ​​the second sheet 10 that is not present refers to the part of the second sheet 10 inside the rectangle R that is not visible in a cross-section of the second sheet 10 in the thickness direction z, and refers to the part of the second sheet 10 that is on the back sheet 3 side of the second surface 10B. If the protrusions 14 are formed in this way, the proportion of the second sheet 10 that is separated from the surface of the absorber 4 on the top sheet 2 side increases, and when the second sheet 10 is viewed from the top sheet 2 side, the second sheet 10 appears whiter. The ratio S2 / S1 may be 4 / 5 or more, or 5 / 6 or more.

[0061] Although the absorbent article of the present invention has been described above with reference to the drawings, the absorbent article of the present invention is not limited to urine pads as shown in the drawings, but may also be disposable diapers, light incontinence pads, or sanitary napkins.

[0062] When the absorbent item is a disposable diaper, the disposable diaper consists, for example, of an anterior abdominal section, a posterior back section, and a crotch section located between these sections and equipped with an absorbent core. The anterior abdominal section corresponds to the part that comes into contact with the wearer's abdomen when wearing the disposable diaper, and the posterior back section corresponds to the part that comes into contact with the wearer's back when wearing the disposable diaper. The crotch section is located between the anterior abdominal section and the posterior back section and corresponds to the part that comes into contact with the wearer's crotch.

[0063] Disposable diapers may be tape-type or pant-type. Tape-type disposable diapers are constructed, for example, with fastening members provided at both ends in the width direction of the back, and by fastening these fastening members to the front of the abdomen, they can be formed into a pant shape when worn. Pant-type disposable diapers have a pant shape with a waist opening and a pair of leg openings, and are formed into a pant shape before being worn.

[0064] If the absorbent article is a disposable diaper, the disposable diaper is formed such that, for example, a laminate in which an absorbent core is placed between a top sheet and a back sheet has an abdominal area, a posterior area, and a crotch area located between them. The disposable diaper can also be constructed by providing an absorbent body in the crotch area of ​​an outer material having an abdominal area, a posterior area, and a crotch area located between them, with an absorbent core placed between a top sheet and a back sheet. In the latter case, by forming the outer material into a pant shape, a pant-type disposable diaper can be made. In either case, the absorbent article of the present invention can be made by joining the top sheet and side sheets at a side joint as described above, and by providing a weakened portion in a part of the side joint. [Explanation of Symbols]

[0065] 1: Absorbent items (urinary pads) 2: Top sheet 3: Back seat 4: Absorbent material 10: Second seat, 10A: First side, 10B: Second side 11: Non-woven layer 12: Plastic film layer 13: Through hole, 13C: Center (of the through hole) 14:Protrusion, 14A:Protrusion base, 14B:Protrusion end, 14E: Edge

Claims

1. An absorbent article having a top sheet, a back sheet, and an absorbent material disposed between them, wherein a second sheet is disposed between the top sheet and the absorbent material, The second sheet is composed of a laminate having a nonwoven fabric layer and a plastic film layer from the top sheet side, and a plurality of through holes are formed in the second sheet. The aforementioned nonwoven fabric layer is composed of spunbond nonwoven fabric. The melting point of the constituent fibers of the nonwoven fabric layer is higher than that of the plastic film layer, and the plastic film layer is bonded to the nonwoven fabric layer. An absorbent article in which the whiteness of the surface on the top sheet side of the second sheet is 76% or more.

2. The absorbent article according to claim 1, wherein the mass per unit area of ​​the nonwoven fabric layer is smaller than the mass per unit area of ​​the plastic film layer.

3. The absorbent article according to claim 1, wherein both the constituent fibers of the nonwoven fabric layer and the plastic film layer are composed of polyolefin resin.

4. The absorbent article according to claim 1, wherein the plastic film layer comprises a high-density polyethylene resin.

5. The absorbent article according to claim 1, wherein the area ratio of the through-holes in the second sheet is 1% or more and 10% or less.

6. The second seat has a protruding portion that extends toward the back seat side along the outer edge of the through hole, The absorbent article according to claim 1, wherein the height of the protruding portion is 0.1 times or more and 0.5 times or less the distance between adjacent protruding portions.

7. The second seat has a protruding portion that extends toward the back seat side along the outer edge of the through hole, The absorbent article according to claim 1, wherein in the cross-section of the second sheet in the thickness direction, the ratio S2 / S1 of the area S1 of a rectangle with the distance between adjacent protrusions as the longer side and the height of the protrusions as the shorter side, and the area S2 of the non-existent portion of the second sheet between adjacent protrusions in the region enclosed by the rectangle, is 3 / 4 or more.

8. The absorbent article according to claim 1, wherein the second sheet has the nonwoven fabric layer penetrating the through hole.

9. The absorbent article according to claim 1, wherein, in a plan view of the absorbent article, the entire second sheet is located inward from the outer edge of the absorbent body.

10. The absorbent article according to claim 1, wherein the plastic film layer is detachably bonded to the nonwoven fabric layer in the second sheet.

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