Absorber product with nonpermeable surface sheet

Technical Field

0001The present invention relates to an absorbent product. More precisely, it relates to an absorbent product capable of preventing the absorbing rate of discharged liquid from significantly lowering with the elapse of time, and having a very small re-wet amount.

Background Art

0002Conventional absorbent products include a liquid-permeable top sheet positioned on the upper side (the side nearer to the wearer's body), a liquid-impermeable back sheet positioned on the lower side (the side away from the wearer's body), and an absorber positioned between these. In case discharged liquid such as urine, feces, and body fluid containing blood (hereinafter referred simply as "discharged liquid" or "liquid") is supplied to this absorbent product, the discharged liquid first passes through the liquid-permeable top sheet and reaches the absorber. In the absorber, the discharged liquid diffuses to the lower side, and when it reaches the liquid-impermeable back sheet, the diffusion ceases. All of the conventional absorbent products use a discharged liquid absorbing mechanism such as this.

0003However, the conventional absorbent products which use the aforementioned absorbing mechanism have two major intrinsic problems. The first problem is that the absorbing rate is lowered as the absorber's absorption volume of discharged liquid increases. The second problem is that the amount of liquid returning from the absorber to the top sheet, or the re-wet amount, increases as the absorption volume of discharged liquid grows larger, especially in the vicinity of the limit of absorbing capacity. These cause an increase of moisture percentage on the surface of the wearer's body during and after discharging of the liquid, making it uncomfortable to keep it on, easily susceptible to becoming sweaty, as well as becoming a primary cause of diaper rash.

0004While on the other hand, in an effort to solve these problems, diverse suggestions regarding performance, structure, air-permeability, etc. of the top sheet and the absorber have been made, but so far no technique reaching the ultimate solution has been found.

0005<patcit id="pcit0001" dnum="EP0861645A"><text>EP-A-0 861 645</text></patcit> relates to disposable training pants for infants, wherein a liquid absorbent core is covered with a liquid impermeable sheet in the crotch region and two liquid laterally zones adjacent to the middle zone.

0006<patcit id="pcit0002" dnum="US3886941A"><text>US-A-3,886,941</text></patcit> describes a disposable diaper comprising an absorber positioned between a liquid impermeable bottom sheet and a liquid impermeable top sheet.

0007<patcit id="pcit0003" dnum="WO9319715A"><text>WO-A-93/19715</text></patcit> relates to an absorbent product with a first surface of a liquid permeable web having a pattern network of pigmented fluid impervious areas thereon.

0008<patcit id="pcit0004" dnum="US4846813A"><text>US-A-4,846,813</text></patcit> discloses an absorbent product comprising a top sheet of an impervious material having a plurality of tapered passages therein.

0009<patcit id="pcit0005" dnum="WO03041626A"><text>WO-A-03/041626</text></patcit> describes a absorber covered with a selectively permeable top sheet and an impermeable back sheet.

0010<patcit id="pcit0006" dnum="GB2023069A"><text>GB-A-2 023 069</text></patcit> relates to disposable diapers having an impermeable top sheet of hydrophobic material which is treated with a surfactant to provide more rapid fluid penetration.

Disclosure of the Invention

0011An object of the present invention, therefore, is to provide an absorbent product which is capable of preventing the absorbing rate from significantly lowering with the elapse of time from the start of use to a final stage when the absorbing capacity of the product reaches a limit, and has a very small re-wet amount. The problem of the present invention has been solved on the base of claims 1 to 32

0012The inventors of the present invention, as a result of research devoted to achieving the above objective, defying traditional common sense, have discovered that it is possible, by positioning on the upper side of an absorber a liquid-impermeable surface sheet in place of a liquid-permeable top sheet to which the discharged liquid is supplied, and by designing a structure wherein a flow passage from the upper side of a surface sheet reaching the lower portion of an absorber is provided, to realize an absorbing mechanism that diffuses a part or all of the discharged liquid from the lower side to the upper side of an absorber. The inventors of the present invention, furthermore, have discovered that, by the above absorbing mechanism, the absorbing rate is prevented from significantly lowering with the elapse of time, and the re-wet amount becomes extremely small. Based on this knowledge, the inventors of the present invention have completed the present invention.

0013In other words, the present invention provides the following: (1) through (34). <ol id="ol0001" compact="compact"><li>(1) An absorbent product with a liquid-impermeable surface sheet positioned on the upper side, a liquid-impermeable back sheet positioned on the lower side, and an absorber containing super absorbent polymer to absorb urine positioned between the surface sheet and the back sheet, wherein a flow passage reading from the uppes side of a surface sheet to the lower surface of an absorber and formed between the absorber and back sheet and/or between two absorbers, wherein the urine moves along the inner surface of the back sheet, is provided to realize an absorbing mechanism that can diffuse a part or all of the urine supplied to the surface sheet to a side of the back sheet.</li><li>(2) The absorbent product according to (1), wherein the flow passage is provided in at least one of the following portions of the absorber; on both front and back ends, on both right and left ends, and in the center.</li><li>(3) The absorbent product according to (1) or (2), wherein the surface sheet is composed of a single-layer synthetic resin film.</li><li>(4) The absorbent product according to (1) or (2), wherein the surface sheet is composed of a laminate of a synthetic resin film and a nonwoven fabric provided on a surface of the upper side of the synthetic resin film.</li><li>(5) The absorbent product according to (3) or (4), wherein the synthetic resin film has concave and convex portions that constitute the flow passage.</li><li>(6) The absorbent product according to any one of (1) to (5), wherein a liquid-permeable guide sheet with the flow passage is laminated to at least a portion of the surface of the upper side of the surface sheet.</li><li>(7) The absorbent product according to (6), wherein the guide sheet covers at least a portion of the lateral sides of the absorber directly or over the surface sheet.</li><li>(8) The absorbent product according to (6) or (7) wherein the guide sheet has concave and convex portions that constitute the flow passage and has apertures in some of or in all of the convex portions.</li><li>(9) The absorbent product according to any one of (1) to (8), wherein a skin-contact sheet composed of liquid-permeable nonwoven fabric is laminated to at least a portion of the surface of the upper side of either the surface sheet or the guide sheet.</li><li>(10) The absorbent product according to any one of (1) to (9), wherein the back sheet is composed of a synthetic resin film.</li><li>(11) The absorbent product according to (10), wherein the synthetic resin film that constitutes the back sheet has air-permeability.</li><li>(12) The absorbent product according to any one of (1) to (9), wherein the back sheet is composed of a laminate of a synthetic resin film and a nonwoven fabric provided on the surface of the lower side of the synthetic resin film.</li><li>(13) The absorbent product according to 14, wherein both the synthetic resin film and the nonwoven fabric that constitute the back sheet have air-permeability.</li><li>(14) The absorbent product according to (12) or (13), wherein the synthetic resin film that constitutes the back sheet has concave and convex portions and has apertures in some of or in all of the convex portions, and the nonwoven fabric that constitutes the back sheet is a water-resistant laminate, of two layers or more, containing one layer or more than one layer of a spunbond nonwoven fabric and one layer or more than one layer of meltblown nonwoven fabric.</li><li>(15) The absorbent product according to any one of (10) to (14), wherein the synthetic resin film that constitutes the back sheet has concave and convex portions constituting a liquid trap portion on the surface of the upper side thereof.</li><li>(16) The absorbent product according to any one of (1) to (15), wherein the absorber is composed of a mixture of super absorbent polymer and fluffy pulp wrapped with a liquid-permeable core-wrapping sheet.</li><li>(17) The absorbent product according to any one of (1) to (15), wherein the absorber has two layers of liquid-permeable nonwoven fabrics and super absorbent polymer inserted in-between.</li><li>(18) The absorbent product according to any one of (1) to (15), wherein the absorber is constructed by having super absorbent polymer supported by means of coating on a liquid-permeable nonwoven fabric.</li><li>(19) The absorbent product according to any one of (1) to (18), wherein a content of the super absorbent polymer in the absorber is 50wt% to 95wt%.</li><li>(20) The absorbent product according to any one of (1) to (19), wherein an absorbent product main body forming an internal space to contain a wearer's objective region when worn and constituting a housing for an absorber unit; the housing for an absorber unit , which provides the space to put an absorbes unit in, adjacent to the absorbent product main body, to communicate to the internal space, and containing the back sheet constituted by another member or by the housing for an absorber unit itself and provided inside the housing for an absorber unit on an inner wall thereof; and an absorber unit structured by combining at least the surface sheet and the absorber, being received removably by the housing for the absorber unit are provided.</li><li>(21) The absorbent product according to (20), wherein the guide sheet is included at least in a portion between the absorbent product main body and the housing for the absorber unit.</li><li>(22) The absorbent product according to (20) or (21), wherein a liquid-permeable skin-contact sheet is included at least in a portion between the absorbent product main body and the housing for the absorber unit.</li><li>(23) The absorbent product according to any one of (20) to (22), wherein laminated plural number of the absorber units are included in the housing for the absorber unit.</li><li>(24) The absorbent product according to any one of (1) to (19), wherein an absorbent product main body forming an internal space to contain a wearer's objective region when worn and constituting a housing for an absorber; the housing for an absorber, which provides the space to put the absorber in, adjacent to the absorbent product main body, to communicate to the internal space, and containing the back sheet constituted by another member or by the housing for an absorber itself and provided inside the housing for an absorber on an inner wall thereof, and an absorber received removably by the housing for the absorber are provided; and, furthermore, the surface sheet is included at least in a portion between the absorbent product main body and the housing for the absorber.</li><li>(25) The absorbent product according to (24), wherein the guide sheet is laminated on the surface of the upper side of the surface sheet.</li><li>(26) The absorbent product according to (24) or 25, wherein a liquid-permeable skin-contact sheet is provided at least on a portion of the surface of the upper side of the surface sheet or the guide sheet.</li><li>(27) The absorbent product according to any one of (24) to 26, wherein laminated plural number of absorbers are included in the housing for the absorber.</li><li>(28) The absorbent product according to any one of (1) to (27), wherein a urine-disposing portion extending from the center to the front section and a feces-disposing portion extending from the center to the back section are provided and the surface sheet is provided only at the urine-disposing portion.</li><li>(29) The absorbent product according to (28), wherein a liquid-impermeable or water-resistant urine back-flow preventing sheet is included inside and/or on the upper side of the absorber, at least at the feces-disposing portion.</li><li>(30) The absorbent product according to (7) wherein a re-wet amount measured under a load of 6.895.10²Pa (0.1psi), 5 minutes after the beginning of the absorption to allow a sodium chloride solution of 0.9wt% in the amount equivalent to 50% of the absorbing capacity of the absorber to be absorbed in the absorber at 25°C under no load, is 5mL or less.</li><li>(31) The absorbent product according to (30), wherein the re-wet amount is 2mL or less.</li><li>(32) The absorbent product according to (7)</li></ol> wherein the absorber's absorbing capacity of sodium chloride solution of 0.9wt% is 300mL or more, and when saline is added to be absorbed by the absorber in the amount of 100mL each time in three separate additions under no load in every 10 minutes, an average re-wet amount after three additions is 5mL or less, and the standard deviation of the re-wet amount is 3mL or less; and when saline is added to be absorbed by the absorber in the amount of 100mL each time in three separate additions under a load of 6.895.10²Pa (0.1psi) in every 10 minutes, the mean absorption time of the three additions is 30 seconds or less, and the standard deviation of the absorption time is 2 seconds or less obtainable by a process wherein the urine is moved to the bottom of the absorber by flow passages.

Brief Description of Drawings

0014<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a set of illustrative cross-section views showing a portion of an example of the absorbent product of the present invention.</li><li><figref idref="f0001">FIG. 2</figref> is a group of illustrative top views and cross-section views showing a portion of examples of the absorbent product of the present invention.</li><li><figref idref="f0002">FIG. 3 (A)</figref> is an illustrative perspective view of an example of the surface sheet with a large number of projections and <figref idref="f0002">FIG. 3 (B)</figref> is its illustrative cross-section view.</li><li><figref idref="f0002">FIGs. 4 (A) and (B)</figref> are illustrative cross-section views, each showing an example of the surface sheet with V-shape grooves, and <figref idref="f0002">FIGs. 4 (C) and (D)</figref> are illustrative cross-section views each showing an example of the ribbed surface sheet.</li><li><figref idref="f0003">FIGs. 5 (A) and (B)</figref> are illustrative perspective views, each showing an example of the surface sheet with V-shape grooves.</li><li><figref idref="f0004">FIG. 6</figref> is a group of illustrative cross-section views, showing a portion of examples of the absorbent product of the present invention.</li><li><figref idref="f0005">FIG. 7</figref> is a group of illustrative top views, showing a portion of examples of the absorbent product of the present invention.</li><li><figref idref="f0006">FIG. 8</figref> is an illustrative perspective view showing an example of the guide sheet that has concave and convex portions constituting flow passages wherein every convex portion has an aperture.</li><li><figref idref="f0007">FIG. 9</figref> is a group of illustrative views, cross-sectional (<figref idref="f0007">FIGs. 9 (A) through (D)</figref>) and perspective (<figref idref="f0007">FIG. 9 (E)</figref>), showing a portion of examples of the absorbent product of the present invention.</li><li><figref idref="f0008">FIG. 10</figref> is a group of illustrative cross-section views, each showing a portion of examples of the absorbent product of the present invention.</li><li><figref idref="f0009">FIG. 11</figref> is a set of illustrative top views, each showing a portion of examples of an absorbent product,</li><li><figref idref="f0009">FIG. 12</figref> is a set of illustrative top views, showing examples of the back sheet used in the present invention.</li><li><figref idref="f0010">FIG. 13</figref> is a set of illustrative cross-section views, each showing a portion of examples of the absorbent product of the present invention.</li><li><figref idref="f0010">FIG. 14</figref> is an illustrative top view showing a portion of an example of an absorbent product.</li><li><figref idref="f0011">FIG. 15</figref> is a set of illustrative cross-section views showing examples of a portion of the absorbent product of the present invention.</li><li><figref idref="f0012">FIG. 16</figref> is an illustrative top view showing a portion of an example of an absorbent product.</li><li><figref idref="f0013">FIG. 17</figref> is a group of illustrative top views, each showing an example of preferred configuration of the back sheet when the member constituting the back sheet itself constitutes the housing for the absorber.</li><li><figref idref="f0014">FIG. 18 (A)</figref> is an illustrative cross-section view showing an example of laminated plural pieces of absorber units. <figref idref="f0014">FIG. 18 (B)</figref> is an illustrative cross-section view showing an example of laminated plural pieces of absorbers, and <figref idref="f0014">FIG. 18 (C)</figref> is an illustrative cross-section view showing an example of a portion of the absorbent product of the present invention, including laminated plural pieces of absorber units.</li><li><figref idref="f0015">FIG. 19</figref> is a group of explanatory drawings, each showing an example of the absorbent product of the present invention with a member for pulling out.</li><li><figref idref="f0016">FIG. 20</figref> is a group of illustrative top views, each showing an example of a portion of an absorbent product.</li><li><figref idref="f0016">FIG. 21</figref> is an illustrative longitudinal section view showing an example of a portion of the absorbent product of the present invention.</li><li><figref idref="f0017">FIG. 22</figref> is an illustrative longitudinal section view showing an example of a portion of the absorbent product of the present invention.</li><li><figref idref="f0017">FIG. 23</figref> is a cross-section view explaining the behavior of the discharged liquid when it is supplied to an absorbent product.</li><li><figref idref="f0018">FIG. 24</figref> is an illustrative cross-section view of the absorbent product used in the Examples.</li><li><figref idref="f0018">FIG. 25</figref> is a set of explanatory drawings showing the method of measuring absorbing rate in the Examples.</li><li><figref idref="f0019">FIGs. 26</figref> are an illustrative front view and an illustrative top view showing the absorbent product that includes plural pieces of absorber units and is used in the Examples.</li><li><figref idref="f0020">FIG. 27</figref> is a set of illustrative cross-section views of the absorber units used in the Examples.</li><li><figref idref="f0021">FIG. 28</figref> is a set of illustrative cross-section views of the absorbent products using the absorber units shown in <figref idref="f0020">FIG. 27</figref>.</li><li><figref idref="f0022">FIG. 29</figref> is an explanatory drawing showing the method of measuring the re-wet amount of the absorbent products, for both urine- and feces-disposing, used in the Examples.</li><li><figref idref="f0022">FIG. 30</figref> is a set of illustrative cross-section views showing a portion of an example of a conventional absorbent product.</li></ul>

Best Mode for Carrying Out the Invention

0015Hereinafter, the absorbent products of the present invention will be described in detail in accordance with preferred embodiments shown in accompanying drawings. Note that each drawing used to describe the present invention is an illustrative drawing and is exaggerated in the thickness of the absorbent product.

0016<figref idref="f0001">FIG. 1</figref> is a set of illustrative cross-section views showing a portion of an example of the absorbent product of the present invention. In <figref idref="f0001">FIG. 1</figref>, the direction perpendicular to the surface of the page is the anteroposterior direction of the absorbent product (in other words, the direction equivalent to front to back of the wearer's body when it is worn) (hereinafter the same applies to all cross-section views). <figref idref="f0001">FIG. 1 (A)</figref> is an explanatory drawing of a structure of the absorbent product of the present invention and <figref idref="f0001">FIG. 1 (B)</figref> is an explanatory drawing of the absorbent product of the present invention in use.

0017As shown in <figref idref="f0001">FIG. 1 (A)</figref>, the absorbent product of the present invention includes a liquid-impermeable surface sheet 10, a liquid-impermeable back sheet 12, and an absorber 14 containing super absorbent polymer (hereinafter also referred to as "SAP"), so that urine can be absorbed and positioned between the surface sheet 10 and the back sheet 12.

0018When urine is supplied to the absorbent product of the present invention, as shown in <figref idref="f0001">FIG. 1 (B)</figref>, because the surface sheet 10 positioned on the upper side is liquid-impermeable, the urine moves on the surface of the surface sheet 10 to the end portions of it. The urine that has moved to the end portions of the surface sheet 10, because the back sheet 12 is liquid-impermeable, moves along the inner surface of the back sheet 12 in the flow passage 16 formed between the absorber 14 and the back sheet 12, while a part of it is being absorbed by the absorber 14, mainly into the bottom side of the absorber 14. In this way, the urine is absorbed by the bottom side of the absorber 14, and then is diffused to the upper side.

0019As described above, the absorbent product of the present invention is characterized by comprising a flow passage to allow a part or all of the discharged liquid supplied to the surface sheet to move to the back sheet side. It is preferred that this flow passage is provided in at least one of the following portions of the absorber; both front and back ends, both right and left ends, and the center.

0020<figref idref="f0001">FIG. 2</figref> is a group of illustrative top views (<figref idref="f0001">FIGs. 2 (A) and (B)</figref>) and cross-section views (<figref idref="f0001">FIGs. 2 (C) and (D)</figref>) showing a portion of examples of the absorbent product of the present invention. In <figref idref="f0001">FIGs. 2 (A) and (B)</figref>, the top-to-bottom direction of the page represents the front-to-back direction of the absorbent product (hereinafter the same applies to all top views). In <figref idref="f0001">FIG. 2</figref>, as a matter of explanatory convenience, only the surface sheet 10, back sheet 12, and the absorber 14 are shown.

0021In the absorbent product shown in <figref idref="f0001">FIGs. 2 (A) and (C)</figref>, the surface sheet 10 fully covers the upper surface of the absorber 14, and the lateral faces and the lower surface thereof are fully covered with the back sheet 12. This absorbent product has the flow passages in all of the following portions of the absorber 14: the front end portion A, back end portion B, left end portion C, and the right end portion D.

0022In the absorbent product shown in <figref idref="f0001">FIGs. 2 (B) and (D)</figref>, two absorbers 14 are positioned side by side with a space in between. Each of two surface sheets 10 fully covers respectively the upper surface of each of the two absorbers 14, and the outer lateral faces and the lower surface thereof are fully covered with one sheet of the back sheet 12. This absorbent product has the flow passages in all of the following portions of the absorber 14: the front end portion A, back end portion B, left end portion C, right end portion D, and the center portion E.

0023<figref idref="f0022">FIG. 30</figref> is a set of illustrative cross-section views showing a portion of an example of a conventional absorbent product. <figref idref="f0022">FIG. 30 (A)</figref> is an explanatory drawing showing the structure of a conventional absorbent product and <figref idref="f0022">FIG. 30 (B)</figref> is an explanatory drawing of a conventional absorber in use.

0024A conventional absorbent product typically includes a liquid-permeable top sheet 11, a liquid-impermeable back sheet 12, and an absorber 14 positioned between the top sheet 11 and the back sheet 12.

0025When discharged liquid is supplied to a conventional absorbent product, as shown in <figref idref="f0022">FIG. 30 (B)</figref>, because the top sheet 11 positioned on the upper side is liquid-permeable, the urine passes through the top sheet 11, is absorbed by the absorber from the top side thereof, and then is diffused to the lower side.

0026In contrast to this, the absorbent product of the present invention is characterized by realizing an absorbing mechanism that diffuses a part of or all of the urine from the lower side to the upper side of the absorber 14 by the structure described above. This mechanism prevents the absorbing rate from significantly lowering with the elapse of time, and ensures a very small re-wet amount.

0027The surface sheet 10 used in the present invention is liquid-impermeable. In this specification, "liquid-impermeable" represents a property of not in effect allowing the urine to permeate.

0028There is no limit in particular to the material or the structure of the surface sheet 10, as long as it is liquid-impermeable. For example, a single-layer sinthetic resin film and a laminate of a synthetic resin film and a nonwoven fabric provided on the surface of the upper side of the synthetic resin film are preferred. As the synthetic resin film, a film made of resin such as PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), polyurethane, or cross-linked PVA (polyvinyl alcohol) and an air-permeable but not liquid-permeable, in other words, breathable film made of above-described resins can be typically employed.

0029One of the preferred embodiments of the synthetic resin film used for a surface sheet 10 is the type with concave and convex portions constituting flow passages 16. However, when the absorbent product of the present invention has a guide sheet as hereinafter described, even if the synthetic resin film does not have concave and convex portions to form flow passages 16, it will also be suitable for use.

0030Furthermore, where flat, smooth and relatively soft synthetic resin film is used as a surface sheet 10, if the surface of the absorber on which the surface sheet is positioned has concave and convex portions, the film may be deformed to be concave and convex, resulting in retention of the discharged liquid. In this case, however, the urine can be quickly moved by pressure-bonding the synthetic resin film and the upper surface of the absorber to smooth them out, or by designing a roof-like structure with a raised center portion and the slopes on both sides thereof.

0031As the configuration with concave and convex portions, the following can be exemplified: a configuration with a large number of projections, a configuration with grooves such as V-shaped or U-shaped grooves, an imbricate configuration (as imbricate scales), and a ribbed configuration.

0032<figref idref="f0002">FIG. 3 (A)</figref> is an illustrative perspective view of an example of the surface sheet with a large number of projections and <figref idref="f0002">FIG. 3 (B)</figref> is its illustrative cross-section view.

0033On the surface sheet 10a, a continuous series of a large number of concave portions function as flow passages 16 for the urine. The surface sheet 10a shown in <figref idref="f0002">FIG. 3</figref> has a large number of projections 18 forming convex portions.

0034As for the size of the concave and convex portions of the surface sheet 10a, when taking into account its handling, cost, etc., it is preferred that the projections 18 forming the convex portions are 0.3mm or greater in height, more preferably 0.5 to 1.5mm.

0035The surface sheet 10a has the advantage of not inhibiting the flow of urine, even if the convex portions are somewhat deformed when in use.

0036<figref idref="f0002">FIGs. 4 (A) and (B)</figref> are illustrative cross-section views, each showing an example of the surface sheet with V-shape grooves respectively, and <figref idref="f0002">FIGs. 4 (C) and (D)</figref> are illustrative cross-section views, each showing an example of the ribbed surface sheet.

0037<figref idref="f0003">FIGs. 5 (A) and (B)</figref> are illustrative perspective views, each showing an example of the surface sheet with V-shape grooves. In <figref idref="f0003">FIG. 5 (A)</figref>, V-shape grooves are formed in one direction only, while in <figref idref="f0003">FIG. 5 (B)</figref> V-shape grooves are formed in two mutually perpendicular directions. Note that there is no limit in particular to the shape, direction, number, intervals, etc. of the grooves. The same applies to the ribs.

0038The positional relationship of the surface sheet 10 and the absorber 14 is explained below.

0039As described above, the surface sheet 10 is positioned on the upper side of the absorber 14. More precisely, examples include, but are not limited to, positional relationships described below.

0040<figref idref="f0004">FIG. 6</figref> is a group of illustrative cross-section views, each showing a portion of examples of the absorbent product of the present invention. In <figref idref="f0004">FIG. 6</figref>, as a matter of explanatory convenience, only the surface sheet 10 and the absorber 14 are shown.

0041In <figref idref="f0004">FIG. 6 (A)</figref>, the surface sheet 10 fully covers, in the left-to-right direction, the upper surface of the absorber 14. In this case, the urine supplied to the surface sheet 10 moves quickly along the surface of the surface sheet 10 to the upper portion of the right and left ends of the absorber 14.

0042In <figref idref="f0004">FIG. 6 (B)</figref>, the surface sheet 10 fully covers, in the left-to-right direction, the upper surface of the absorber 14, and further covers the right and left lateral surfaces thereof. In this case, the urine supplied to the surface sheet 10 moves quickly along the surface of the surface sheet 10 to the lower portion of the right and left ends of the absorber 14. Therefore, the proportion of urine absorbed from the lower portion of the absorber 14 is greater in comparison to the case described in <figref idref="f0004">FIG. 6 (A)</figref>.

0043In <figref idref="f0004">FIG. 6 (C)</figref>, the surface sheet 10 fully covers, in the left-to-right direction, the upper surface of the absorber 14, and further covers the right and left lateral surfaces, as well as a portion of the lower surface thereof. In this case, the urine supplied to the surface sheet 10 moves quickly along the surface of the surface sheet 10 to the lower surface of the absorber 14. Therefore, the urine is more easily absorbed from the center portion of the lower surface of the absorber 14 than in the case shown in <figref idref="f0004">FIG. 6 (B)</figref>.

0044In <figref idref="f0004">FIG. 6 (D)</figref>, the surface sheet 10 partially covers, in the left-to-right direction, the upper surface of the absorber 14. In this case, the urine supplied to the surface sheet 10 moves quickly along the surface of the surface sheet 10 to the upper surface nearer to the ends of the absorber 14. A part of the urine, therefore, is absorbed from the upper surface of the absorber 14, but the rest is absorbed from the lateral surfaces and the lower surface of the absorber 14.

0045In <figref idref="f0004">FIG. 6 (E)</figref>, two absorbers 14 are positioned side by side, with the flow passage 16 in between, and each of two surface sheets 10 fully covers, in the left-to-right direction, the upper surface of each of the two absorbers 14, as well as the lateral surfaces on right and left thereof. Furthermore, the surface sheet 10 extends into the flow passage 16. In this case, the urine supplied to the surface sheet 10 moves quickly along the surface of the surface sheet 10 to the lower portion of the flow passage 16 while a part of the liquid moves to the lower portion of the outside ends also. The urine , therefore, is easily absorbed from the portions of the absorber equivalent to the center portion as well as the outside portions on both sides of the absorbent product.

0046In <figref idref="f0004">FIG. 6 (F)</figref>, two absorbers 14 are positioned side by side with the flow passage 16 in between, and each of two surface sheets 10 fully covers the upper surface of each of the two absorbers 14. In this case, the urine supplied to the surface sheet 10 moves quickly along the surface of the surface sheet 10 to the upper portion of the outside end of each absorber 14, while it also moves through the flow passage 16 to the lower portion of the flow passage 16. The urine is easily absorbed from the lateral surfaces as well as the lower surface of each absorber 14.

0047<figref idref="f0005">FIG. 7</figref> is a group of illustrative top views, each showing a portion of examples of the absorbent product of the present invention. In <figref idref="f0005">FIG. 7</figref>, as a matter of explanatory convenience, only the surface sheet 10 and the absorber 14 are shown.

0048In <figref idref="f0005">FIG. 7 (A)</figref>, the surface sheet 10 fully covers the upper surface of the absorber 14.

0049In <figref idref="f0005">FIG. 7 (B)</figref>, two absorbers 14 are positioned side by side with the flow passage 16 in between, and each of two surface sheets 10 fully covers the upper surface of each of the two absorbers 14.

0050In <figref idref="f0005">FIG. 7 (C)</figref>, the surface sheet 10 fully covers, in the left-to-right direction, a portion, in the anteroposterior direction, of the upper surface of the absorber 14. A portion of the upper surface of the absorber 14 is exposed in the front and back end portions of the surface sheet 10.

0051In <figref idref="f0005">FIG. 7 (D)</figref>, the surface sheet 10 fully covers, in the anteroposterior direction, a portion, in the left-to-right direction, of the upper surface of the absorber 14. The upper surface of the absorber 14 is partially exposed in the right and left end portions of the surface sheet 10.

0052In <figref idref="f0005">FIG. 7 (E)</figref>, two surface sheets 10 cover the right and left end portions of the upper surface of the absorber 14, and a portion of the upper surface of the absorber is exposed in the center portion.

0053In <figref idref="f0005">FIG. 7 (F)</figref>, the surface sheet 10 fully covers the upper surface of the absorber 14, but the surface sheet 10 has a liquid-permeable portion 20 in the center in the left-to-right direction.

0054In <figref idref="f0005">FIG. 7 (G)</figref>, the surface sheet 10 fully covers the upper surface of the absorber 14, but the surface sheet 10 has liquid-permeable portions 20 at two predetermined portions in the left-to-right direction.

0055There is no limit in particular to the material, structure, etc. of the liquid-permeable portions 20 in <figref idref="f0005">FIGs. 7 (F) and (G)</figref> as long as they are liquid-permeable. For example, the surface sheet 10 with apertures to make it liquid-permeable is acceptable, a portion of the surface sheet 10 may be constructed with a liquid-permeable material (for example, a spunbond nonwoven fabric), etc. In this specification, "liquid-permeable" represents a characteristic of in effect allowing the urine to permeate.

0056In both cases of <figref idref="f0005">FIGs. 7(A) and (B)</figref>, the urine supplied to the surface sheet 10 is absorbed from the lateral and lower surfaces of the absorber 14 without being absorbed by the upper surface thereof.

0057In all of the cases of <figref idref="f0005">FIGs. 7 (C) through (G)</figref>, a part of the discharged liquid supplied to the surface sheet 10 is absorbed from the upper surface of the absorber 14 through the exposed portions of the absorber 14 or through the liquid-permeable portions 20, and the rest is absorbed from the lateral surfaces and lower surface of the absorber 14.

0058As just described, when urine is absorbed from all portions including the upper, lateral, and lower surfaces of the absorber 14 an increased absorption rates, obtained but in terms of the re-wet amount, the performance tends to get slightly worse. Another absorbent product has the surface sheet positioned so as to expose a portion of the upper surface of the absorber, an absorber product wherein the surface sheet is positioned only partially in the vicinity of the urinary excretion part of the wearer to ensure dryness of that local part.

0059The positional relationships described in <figref idref="f0004">FIGs. 6 (A) through (F)</figref> and the positional relationships described in <figref idref="f0005">FIGs. 7 (A) through (G)</figref> may be combined in as many ways as possible, to realize various positional arrangements. Furthermore, the surface sheet 10 and the absorber 14 may also be arranged in other positional relationships than those described above.

0060In the present invention, one of the preferred embodiments has a liquid-permeable guide sheet with the flow passage laminated to at least a portion of the surface of the upper side of the surface sheet. The guide sheet assists the supplied discharged liquid to move to the lower side of the absorber through its flow passage. In case the guide sheet is laminated, therefore, even if the synthetic resin film constituting the surface sheet does not have concave and convex portions to form flow passages, rapid diffusion, by the guide sheet, of the discharged liquid to the lower side of the absorber will be accomplished.

0061The urine moves through the flow passages of the guide sheet by capillary action, moistening, penetration, and diffusion. In order to ensure efficient movement of the urine, it is preferred that the guide sheet has hydrophilicity and a certain extent of thickness. More precisely, for example, a film with concave-convex apertures having liquid distribution effect or a concave-convex molded plastic net with liquid distribution effect (suggested by the inventors of the present invention in the pamphlet of International Publication No. <patcit id="pcit0007" dnum="WO02065965A"><text>02/065965</text></patcit>, for example); and bulky laminated nonwoven fabrics (for example, a composite sheet made by bonding a paper or nonwoven fabric layer having a flat and smooth surface and a fiber web layer having a bulky surface of concave and convex portions suggested by the inventors of the present invention in the specification of <patcit id="pcit0008" dnum="JP2001297161A"><text>JP 2001-297161 A</text></patcit> and the specification of <patcit id="pcit0009" dnum="JP2001297162A"><text>JP 2001-297162 A</text></patcit>) may be used.

0062One of the preferred embodiments of the guide sheet has concave and convex portions constituting the flow passages and has apertures in part of or all of the convex portions.

0063<figref idref="f0006">FIG. 8</figref> is an illustrative perspective view showing an example of the guide sheet that has concave and convex portions constituting flow passages, wherein every convex portion has an aperture.

0064On the guide sheet 22, a continuous series of a large number of concave portions function as flow passages 16 for the urine. The guide sheet 22 shown in <figref idref="f0006">FIG. 8</figref> has a large number of projections 24 forming convex portions, each projection 24 having an aperture 26 at the top.

0065In the case of a guide sheet with apertures at convex portions as shown in <figref idref="f0006">FIG. 8</figref>, even if it is made of hydrophobic material, these apertures will also function as the flow passages for the urine. In other words, the urine moves via the apertures from one side to the other side of the guide sheet.

0066The apertures may be provided only in some of the convex portions or in all of the convex portions. Furthermore, though there is no limit in particular to the number of apertures per unit area, 1.0 to 100 apertures/cm² is preferable.

0067As for the size of the concave and convex portions of the guide sheet 22, when taking into account its handling, cost, etc., it is preferred that the projections 24 forming the convex portions have a height h of 0.3mm or greater, more preferably 0.5 to 1.5mm.

0068The guide sheet 22 has an advantage of not inhibiting the flow of urine, even if the convex portions are somewhat deformed when in use.

0069It is preferred that the projections of the guide sheet 22 face downward. In this way, the flow passages formed in between the projections 24 and the surface of the surface sheet become large, resulting in smoother movement of the urine from the surface of the guide sheet to the surface of the surface sheet.

0070In the present invention, one of the preferred embodiments has a skin-contact sheet made of liquid-permeable nonwoven fabric laminated to at least a part of the surface of the upper side of the surface sheet or the guide sheet. The skin-contact sheet is a portion that directly touches the wearer's skin, and by providing this skin-contact sheet, the comfortability of the wearer may be improved. For the skin-contact sheet, the material used as a top sheet in the conventional absorbent products may be used, and skin-care performance, such as an antibacterial property, may be given to it. Furthermore, a special contact sheet such as the one suggested by the inventors of the present invention in the pamphlet of International Publication No. <patcit id="pcit0010" dnum="WO0200154A"><text>02/00154</text></patcit> may also be used.

0071The preferred examples of the structure of the aforementioned surface sheet, guide sheet, and the skin-contact sheet will be explained in detail.

0072<figref idref="f0007">FIG. 9</figref> is a group of illustrative views, cross-sectional (<figref idref="f0007">FIGs. 9 (A) through (D)</figref>) and perspective (<figref idref="f0007">FIG. 9 (E)</figref>), showing a portion of examples of the absorbent product of the present invention. In <figref idref="f0007">FIG. 9</figref>, as a matter of explanatory convenience, only the surface sheet 10, absorber 14, guide sheet 22, and the skin-contact sheet 28 are shown.

0073In <figref idref="f0007">FIG. 9 (A)</figref>, the surface sheet 10 is composed of a laminate of a synthetic resin film and a nonwoven fabric provided on the surface of the upper side of the synthetic resin film.

0074In <figref idref="f0007">FIG. 9 (B)</figref>, the surface sheet 10 is composed of a single-layer sinthetic resin film, wherein the synthetic resin film has concave and convex portions that form flow passages 16, and the skin-contact sheet 28 made of liquid-permeable nonwoven fabric is laminated on the surface of the upper side of the surface sheet 10.

0075In <figref idref="f0007">FIG. 9 (C)</figref>, the surface sheet 10 is composed of a single-layer sinthetic resin film, and the liquid-permeable guide sheet 22 with the flow passages 16 is laminated on the surface of the upper side of the surface sheet 10.

0076In <figref idref="f0007">FIG. 9 (D)</figref>, the skin-contact sheet 28 made of liquid-permeable nonwoven fabric is further laminated on the surface of the upper side of the guide sheet shown in <figref idref="f0007">FIG. 9 (C)</figref>.

0077In <figref idref="f0007">FIG. 9 (E)</figref>, the surface sheet 10 is composed of a single-layer sinthetic resin film, and the liquid-permeable guide sheet 22 with a large number of apertures 26 as well as the flow passages 16, is laminated on the surface of the upper side of the surface sheet 10. The surface sheet 10 and the guide sheet 22 are integrated by the bonding portions 22a.

0078<figref idref="f0008">FIG. 10</figref> is a group of illustrative cross-section views, each showing a portion of examples of the absorbent product of the present invention. In <figref idref="f0008">FIG. 10</figref>, as a matter of explanatory convenience, only the surface sheet 10, absorber 14, and the guide sheet 22 are shown.

0079In <figref idref="f0008">FIG. 10 (A)</figref>, the surface sheet 10 covers the upper surface as well as the left end and the right end portions of the absorber 14, and the guide sheet 22 covers the upper surface as well as the left end and the right end portions of the absorber 14, and further, a part of the lower surface thereof.

0080In <figref idref="f0008">FIG. 10 (B)</figref>, the surface sheet 10 covers the upper surface of the absorber 14, and the guide sheet 22 covers the upper surface as well as the left and right end portions of the absorber 14.

0081In <figref idref="f0008">FIG. 10 (C)</figref>, the surface sheet 10 covers the upper surface of the absorber 14, and the guide sheet 22 covers the lower surface as well as the left and right end portions of the absorber 14, and further, a part of the upper surface thereof.

0082As shown in <figref idref="f0008">FIGs. 10 (A) through (C)</figref>, when the guide sheet 22 covers at least a part of the lateral surface of the absorber 14 directly or over the surface sheet 10, diffusion of the urine becomes faster.

0083<figref idref="f0009">FIG. 11</figref> is a set of illustrative top views, each showing a portion of examples of an absorbent product.

0084In <figref idref="f0009">FIG. 11</figref>, as a matter of explanatory convenience, only the surface sheet 10, absorber 14, and the guide sheet 22 are shown.

0085In <figref idref="f0009">FIG. 11 (A)</figref>, the surface sheet 10 fully covers, in the anteroposterior direction, a portion in the left-to-right direction of the upper surface of the absorber 14. A portion of the upper surface of the absorber 14 is exposed in the right and left end portions of the surface sheet 10. And the guide sheet 22 fully covers in the left-to-right direction a portion, in the anteroposterior direction, of the upper surface of the surface sheet 10, and a portion of the upper surface of the absorber 14 and a portion of the upper surface of the surface sheet 10 are exposed.

0086In <figref idref="f0009">FIG. 11 (B)</figref>, the surface sheet 10 and the absorber 14 are positioned in the same way as they are in <figref idref="f0009">FIG. 11 (A)</figref>, but because the guide sheet 22 is in the hape of a cross, a portion of the upper surface of the absorber 14 and the a portion of the upper surface of the surface sheet 10 are exposed in a different manner from <figref idref="f0009">FIG. 11 (A)</figref>.

0087The back sheet 12 used in the present invention is liquid-impermeable. There is no limit to the material, structure, etc. of the back sheet 12 as long as it is liquid-impermeable, and the same type of back sheet as the one used in the conventional absorbent products. The preferred examples are a single-layer synthetic resin film and a laminate of a synthetic resin film and a nonwoven fabric provided on the surface of the lower side of the synthetic resin film.

0088For the synthetic film, for example, there are a matted PE film and a porous air-permeable film. The air-permeable film is a synthetic resin film made porous by filler addition and polymer blending with its MVTR (Moisture Vapor Transmission Rate) indicating around 1000 to 6000L/(m²*24hrs.). Typical air-permeable films include Espoir (manufactured by Mitsui Chemicals Inc.) and Porum (manufactured by Tokuyama Corp.), both manufactured by adding CaCO₃ as a filler to PE resin.

0089In the present invention, when the back sheet is composed of a single-layer synthetic resin film, it is preferred that the synthetic resin film is air-permeable, and when the back sheet is composed of a laminate of a synthetic resin film and nonwoven fabrics provided on the surface of the lower side of the synthetic resin film, it is preferred that both the synthetic resin film and the nonwoven fabrics are air-permeable. As described in these examples, when the back sheet has an air-permeable property, the comfortability of the wearer is improved. Furthermore, by using the stretchable composite sheet (such as the one described in <patcit id="pcit0011" dnum="JP10195746A"><text>JP 10-195746 A</text></patcit>) in some or all parts of the back sheet, the fitting and the like are further improved.

0090In the present invention, it is preferred that the synthetic resin film composing the back sheet has concave and convex portions that form liquid trap portions on the surface of the upper side. In the present invention, because the urine is first absorbed from the lower side and then later from the upper side of the absorber, the urine is uniformly diffused to the entire area of the lower side of the absorber by providing concave and convex portions on the back sheet.

0091As the configuration of concave and convex portions, the following can serve as examples: a configuration with a large number of projections, a configuration with grooves (such as V-shaped or U-shaped grooves), an imbricate configuration (as imbricate scales), and a ribbed configuration.

0092<figref idref="f0009">FIG. 12</figref> is a set of illustrative top views, showing examples of the back sheet used in the present invention. The back sheet 12 in <figref idref="f0009">FIG. 12 (A)</figref> has a large number of grooves 30, forming concave portions. The back sheet 12 in <figref idref="f0009">FIG. 12 (B)</figref> has a large number of projections 32, forming convex portions.

0093One of the preferred embodiments of the back sheet is, precisely, a film processed to have concave and convex portions (for example, the one suggested by the inventors of the present invention in the specification of <patcit id="pcit0012" dnum="JP2001135239A"><text>JP 2001-135239 A</text></patcit>) wherein the synthetic resin film that constitutes the back sheet has concave and convex portions and has apertures in some of or in all of the convex portions, while the nonwoven fabric that constitutes the back sheet is a water-resistant laminate, of two layers or more, containing one layer or more of spunbond nonwoven fabrics and one layer or more of meltblown nonwoven fabrics.

0094As this kind of a laminate, the preferred examples include a laminate of film with apertured concave-and-convex portions and water-resistant SMS nonwoven fabric (nonwoven fabric of three-layer structure of spunbond/meltblown/spunbond) suggested by the inventors of the present invention in the specification of <patcit id="pcit0013" dnum="JP2001124237A"><text>JP 2001-124237 A</text></patcit>.

0095The positional relationship of the surface sheet 10, the absorber 14, and the back sheet 12 is explained below.

0096As described above, the back sheet 12 is positioned on the lower side of the absorber 14. More precisely, examples include, but are not limited to, positional relationships described below.

0097<figref idref="f0010">FIG. 13</figref> is a set of illustrative cross-section views, each showing a portion of examples of the absorbent product of the present invention. In <figref idref="f0010">FIG. 13</figref>, as a matter of explanatory convenience, only the surface sheet 10, absorber 14, the back sheet 12, and the guide sheet 22 are shown.

0098In <figref idref="f0010">FIG. 13 (A)</figref>, the back sheet 12 covers the lower surface as well as both the right and left lateral surfaces of the absorber 14, whose upper surface is covered by the surface sheet 10.

0099In <figref idref="f0010">FIG. 13 (B)</figref>, the back sheet 12 covers the lower surface, as well as both the right and left lateral surfaces of the absorber 14, whose upper surface is covered by the surface sheet 10 and furthermore, whose upper surface, both the right and left lateral surfaces and a portion of the lower surface are covered by the guide sheet 22.

0100<figref idref="f0010">FIG. 14</figref> is an illustrative top view showing a portion of an example of an, absorbent product.

0101In <figref idref="f0010">FIG. 14</figref>, as a matter of explanatory convenience, only the surface sheet 10, absorber 14, and the back sheet 12 are shown.

0102In <figref idref="f0010">FIG. 14</figref>, the surface sheet 10 covers a portion of the upper surface of the absorber 14, and the back sheet 12 fully covers the absorber 14 and the lower surface of the surface sheet 10.

0103As the absorber used in the present invention, a conventional absorber may be used. More precisely, an absorber used in an absorbent product currently on the market, composed by wrapping a mixture of SAP and fluffy pulp with a liquid-permeable core-wrapping sheet made with material such as tissue paper, spunbond nonwoven fabric, and film with apertures is an example.

0104Also, for example, there is a highly water-absorbing sheet obtained by the Air Laid method. The Air Laid method is a method for obtaining a highly water-absorbing sheet by mixing pulverized pulp and SAP, adding a binding agent (such as a heat-sealed fiber) to the mixture, and shaping it into a sheet form and heating it. NovaThin (U.S. Registered Trademark), manufactured by Rayonier Inc. in the U.S., and KINOCLOTH (Registered Trademark), manufactured by Oji Kinocloth Co., Ltd., for example, are known as highly water-absorbing sheets obtained by this method.

0105There are also other examples, such as a highly water-absorbing sheet obtained by making SAP into dispersion slurry and the like, and by the method of coating to have the SAP held on at least one of two surfaces of a discharged-liquid-permeable sheet of a liquid-permeable nonwoven fabric and the like. This highly water-absorbing sheet is precisely described in the specification and other parts of <patcit id="pcit0014" dnum="JP10168230A"><text>JP 10-168230 A</text></patcit>, the specification and other parts of <patcit id="pcit0015" dnum="JP10314217A"><text>JP 10-314217 A</text></patcit>, and the specification and other parts of <patcit id="pcit0016" dnum="JP2000201975A"><text>JP 2000-201975 A</text></patcit>, suggested by the inventors of the present invention. The SAP dispersion slurry here is preferably a slurry obtained by dispersing SAP and Micro Fibrillated Cellulose (MFC) in a mixed solvent of water and ethanol. MegaThin (Registered Trademark), manufactured by Japan Absorbent Technology Institute, for example, is known as a highly water-absorbing sheet obtained by this method.

0106There are also other examples, such as a highly water-absorbing sheet obtained by the method of applying a large amount of SAP to fluffy nonwoven fabric, and settling it with a hot-melt binder, emulsion binder, water-soluble fiber, etc.; a highly water-absorbing sheet obtained by the method of mixing fibrous SAP and PET (polyethylene terephthalate) fibers, and forming the mixture into a web; as well as a highly water-absorbing sheet containing two layers of liquid-permeable nonwoven fabrics and SAP held in between the layers thereof.

0107It is preferred that the thickness in the highly water-absorbing sheet is 1.5mm or less, and more preferably 1mm or less.

0108It is preferred that the SAP content of the aforementioned absorber is 50wt% or more, and more preferably 60 to 95wt%.

0109The absorbent product of the present invention, as described below, may have a plural number of absorbers, but when a mixture of SAP and fluffy pulp is used as an absorber as described above, it is bulky, and while absorbing capacity is great, retention is relatively small, so a single layer of the mixture is usually used. The conventional absorbent product which uses an absorber such as this have a great re-wet amount, but in the present invention a liquid-impermeable surface sheet is used, and thus, may decrease the re-wet amount to a small percent of that of the conventional absorbent products.

0110At the same time, when the aforementioned highly water-absorbing sheet is used, because the highly water-absorbing sheet is extremely thin with relatively high retention compared to the absorption capacity, and its demand wettability is high, one of the preferred embodiments , as suggested by the inventors of the present invention in <patcit id="pcit0017" dnum="JP2002113800A"><text>JP 2002-113800 A</text></patcit>, is structured with a multiple layer of a plural number of absorbers, and which has the urine absorbed by the absorber starting at the lower layer and gradually at higher layers.

0111Next, the embodiments of the absorbent product of the present invention are explained below.

0112The absorbent product of the present invention can be easily obtained by using a conventional absorbent product such as a tape-type and a pull-on type (pants-type) baby diaper and adult incontinence diaper, a sanitary napkin for women, and other incontinence products. In other words, an absorbent product of the present invention with significantly improved performance can be obtained by inserting a surface sheet, preferably a surface sheet combined with a guide sheet, in between a top sheet and an absorber of a conventional absorbent product.

0113One of the preferred embodiments of the absorbent product of the present invention is an absorbent product including an absorbent product main body that can form an internal space to contain the wearer's objective region when worn; housing for an absorber unit adjacent to the absorbent product main body to communicate to the internal space, and containing the back sheet on the inner walls thereof; and an absorber unit structured by combining at least the surface sheet and the absorber, being received removably by the housing for the absorber.

0114<figref idref="f0011">FIG. 15</figref> is a set of illustrative cross-section views showing examples of a portion of the aforementioned absorbent product.

0115The absorbent product 50 shown in <figref idref="f0011">FIG. 15 (A)</figref> includes an absorbent product main body 52 that can form an internal space to contain the wearer's objective region when worn; housing for an absorber unit 54 adjacent to the absorbent product main body 52 to communicate to the internal space, and containing the back sheet 12 on the inner walls thereof; and an absorber unit 56 structured by combining the surface sheet10 and the absorber 14, being received removably by the housing for the absorber unit. Note that only a part of the absorbent product main body 52 is shown, and the space in upper side of the drawing represents the aforementioned inner space. The surface sheet 10, back sheet 12 and the absorber 14 are as described above.

0116In <figref idref="f0011">FIG. 15 (A)</figref>, the member constituting the absorbent product main body 52 also constitutes housing for an absorber unit 54, and a back sheet 12 constituted by another member is provided inside the housing for an absorber unit 54. In the present invention, however, it is acceptable as long as the housing for an absorber unit contains a back sheet inside thereof, and the member constituting the back sheet, for example, may also constitute the housing for an absorber unit.

0117As the absorbent product main body 52, an absorbent product main body comprising a laundry-proof material that can be used plural times, such as a conventional diaper cover, may be used. It is preferred that the absorbent product main body 52 is a plain knit product such as a stockinet knit product, because it improves the fitting when worn.

0118On both the right and left end portions of the back sheet 12 shown in <figref idref="f0011">FIG 15</figref>, side-gather members 58 are provided. The structure of the side-gather members 58 may be a conventional structure, comprising a bundle of polyurethane filament, elastic film, etc.

0119The absorbent product 51 shown in <figref idref="f0011">FIG. 15 (B)</figref> is the same as the absorbent product 50, except that the latter includes the guide sheet 22 as shown in the drawing.

0120The absorbent products 50 and 51 of the present invention shown in <figref idref="f0011">FIGs. 15 (A) and (B)</figref> have the absorbent product main body 52 and the housing for the absorber unit 54 directly communicated to each other (in other words, the surface sheet 10 or the guide sheet 22 is exposed), but the aforementioned liquid-permeable skin-contact sheet may be included in at least a portion of the space in between these two.

0121In <figref idref="f0011">FIG. 15</figref>, one absorber unit is housed in the housing for the absorber unit 54, but in the present invention as described below, a laminated plural number of absorber units may also be housed.

0122One of the preferred embodiments of the absorbent product of the present invention is an absorbent product which includes a main body made of an absorbent product that can form an internal space to contain the wearer's objective region when worn; housing for an absorber adjacent to the absorbent product main body to communicated to the internal space and containing the back sheet on the inner walls thereof; an absorber, being received removably by the housing for the absorber; and a surface sheet contained at least in a portion of the space between the absorbent product main body and the housing for the absorber.

0123<figref idref="f0012">FIG. 16</figref> is an illustrative top view showing a portion of an example of the aforementioned absorbent product.

0124The absorbent product 60 shown in <figref idref="f0012">FIG. 16</figref> includes an absorbent product main body 52 that can form an internal space to contain the wearer's objective region when worn; housing for an absorber 55 adjacent to the absorbent product main body 52 to communicate to the internal space, and containing the back sheet (not shown) on the inner walls thereof; an absorber 14 received removably by the housing for the absorber 55, and the surface sheet 10 attached to the housing for the absorber 55 to wrap the absorber 14 over the upper surface thereof. Note that only a part of the absorbent product main body 52 is shown, and the space in upper side of the drawing represents the aforementioned inner space. The surface sheet 10, back sheet 12 and the absorber 14 are as described above.

0125In the present invention, as long as the housing for an absorber contains a back sheet inside thereof it is acceptable; for example the member constituting the absorbent product main body may constitute the housing for an absorber 55, a back sheet may be constituted inside the housing for an absorber with another different member, and the member constituting the back sheet may also constitute the housing for an absorber.

0126<figref idref="f0013">FIG. 17</figref> is a group of illustrative top views, each showing an example of preferred configuration of the back sheet when the member constituting the back sheet itself constitutes the housing for the absorber. In a structure such as this, it is preferred that a durable and water-resistant material such as Gore-Tex, for example, is used as a back sheet.

0127Every back sheet 12 in <figref idref="f0013">FIGs. 17 (A) through (E)</figref> has a large number of projections 32, forming convex portions. The back sheet 12 in <figref idref="f0013">FIG. 17 (F)</figref> has a large number of linear grooves 30, forming concave portions. Quilted cloth, for example, may be used. The back sheet 12 in <figref idref="f0013">FIG. 17 (G)</figref> has a large number of dot-like projections 32, forming convex portions.

0128The absorbent product main body 52 and the side-gather member 58 are the same as those of the absorbent product 50 shown in <figref idref="f0011">FIG. 15</figref>.

0129Also, even if the back sheet is constituted with a different material inside of the housing for the absorber, the same effect as in the case concavity and convex are provided on the back sheet will be obtained, by providing concave and convex portions on the profile of the member comprising the housing for the absorber, and achieving the effect of concave and convex portions on the back sheet that is laminated on it.

0130The absorbent product 60 with the aforementioned guide sheet laminated on the surface of the upper side surface sheet 10 is one of the preferred embodiments of the present invention. In this embodiment, the guide sheet may be laminated so as to cover the surface sheet over the upper side thereof, as well as to wrap the lateral surfaces of the absorber from the lower side thereof.

0131Also, the absorbent product 60 may include a liquid-permeable skin-contact sheet, same as in the case of the absorbent products 50 and 51.

0132Furthermore, the absorbent product 60 may house a plural number of laminated absorbers 14, as described below.

0133One of the preferred embodiments of the absorbent product of the present invention, as described above, includes laminated plural pieces of absorber units or absorbers. A thin and compact absorber with high SAP content, when for instance the aforementioned highly water-absorbing sheet is used, is especially preferred.

0134There is no limit in particular to the number of the absorber units or the absorbers in the laminate, as long as the laminate has two layers or more, but it is preferred that the laminate has 5 layers or less. As long as the number of layers does not exceed 5, it prevents a compact absorbent product from becoming too bulky.

0135<figref idref="f0014">FIG. 18 (A)</figref> is an illustrative cross-section view showing an example of laminated plural pieces of absorber units. <figref idref="f0014">FIG. 18 (B)</figref> is an illustrative cross-section view showing an example of laminated plural pieces of absorbers. In <figref idref="f0014">FIG. 18 (A)</figref>, three layers of laminated absorber units 56 are shown. In <figref idref="f0014">FIG. 18 (B)</figref>, three layers of laminated absorbers 14 are shown.

0136<figref idref="f0014">FIG. 18 (C)</figref> is an illustrative cross-section view showing an example of a portion of the absorbent product of the present invention, including laminated plural number of absorber units. The absorbent product 70 shown in <figref idref="f0014">FIG. 18</figref> uses the absorber unit 56, which is in a single layer in the absorbent product 50 shown in <figref idref="f0003">FIG. 5 (A)</figref>, by laminating them in three layers as shown in <figref idref="f0014">FIG. 18 (A)</figref>.

0137When the absorbent product of the present invention is used by laminating them in multiple layers, use of more than once is possible, corresponding to the number of layers, reducing the frequency of exchange of the absorbent product, for example from three to five times a day to once or twice a day. The reason why use more than once is possible is explained below.

0138In the absorbent product of the present invention, as mentioned above, the urine is absorbed mainly from the lower side of the absorber, and then is diffused to the upper side. The majority of the urine is absorbed from the lower-most absorber. And then, after being absorbed from the lower-most absorber to the limit of or in the vicinity of the limit of its absorbing capacity, the urine is absorbed into the second absorber from the bottom. In this way, absorbing of the urine progresses from the bottom to the top, until the absorbing capacity of the upper-most absorber reaches the limit. Therefore, by separating the absorber which has absorbed the urine to the limit of its absorbing capacity from the rest individually at the proper time, use of more than once becomes possible. In this way, not only feelings of bulkiness or of weight felt by the wearer is eliminated, but also the lowering of the absorbing capacity, caused by the pressure from the weight of the absorber with its absorbed, urine, is prevented.

0139In contrast to this, if an absorbent product that uses a conventional liquid-permeable top sheet is made into multiple layers, absorbing action progresses from the top to the bottom, but before the urine is absorbed to the limit of the absorbing capacity of the absorber on the upper side, absorbing into the absorber below it begins. Thus, the urine is absorbed by all the absorbers, especially in the portion in the center, when viewed from above the surface where the discharged liquid is supplied. As described above, because all the absorbers start swelling gradually in the initial stage of use, and as a result, the discharged liquid does not diffuse entirely in the individual absorber, separating an individual absorber from the rest does not work. Separation in this case will extremely worsen the rate of utilization. And because separation of the absorber individually from the rest is not possible, it ends up becoming heavy. Therefore, making a multiple- layer absorbent product with a conventional absorbent product is not realistic.

0140Furthermore, in the absorbent product of the present invention, even if plural number of absorbers are used, the re-wet amount will be extremely small, as in the case of a single-layer absorber; and the upper surface of the upper-most absorber will stay from the start of use till right before the end of use as dry as it is before use, leading to improved comfortability for the wearer.

0141There is no limit in particular to the structure enabling the separation of the used absorber from the rest, but the structure comprising an aperture portion, preferably an aperture portion in the outer space at the housing for the absorber unit or the housing for the absorber may be an example. The structures suggested by the inventors of the present invention in the specification of <patcit id="pcit0018" dnum="JP2002233209A"><text>JP 2002-233209 A</text></patcit> are suitable for use.

0142Especially, the structure that includes a member for pulling out is preferred. The structure described in <patcit id="pcit0019" dnum="JP7012117U"><text>JP 7-12117 U</text></patcit> has one of the preferred examples of this member for pulling out.

0143<figref idref="f0015">FIG. 19</figref> is a group of explanatory drawings, each showing an example of the absorbent product of the present invention with a member for pulling out. <figref idref="f0015">FIG. 19 (A)</figref> is a top view, <figref idref="f0015">FIG. 19 (B)</figref> is a longitudinal section view, and <figref idref="f0015">FIG. 19 (C)</figref> is a longitudinal section view of the absorbent product including the absorber. In <figref idref="f0015">FIGs. 19 (B) and (C)</figref>, the left side of the drawing is the front side of the absorbent product and the right side of the drawing is the back side of the absorbent product. In <figref idref="f0015">FIGs. 19 (A) to (C)</figref>, the back sheet is not shown and M represents the body of a wearer.

0144The absorbent product 80 shown in <figref idref="f0015">FIG. 19</figref> has a member for pulling out 62, which is in a tape form, positioned in the upper portion of the front end of the absorber 14. It is preferable if the member for pulling out 62 has an adhesive layer 64 on its lower surface. In that case, it is preferred that a release layer 66 is provided in the portion corresponding to the adhesive layer 64, and that the release layer 66 is in close contact with the surface of the adhesive layer 64 before it is incorporated in the absorbent product 80. In the absorber 14, housed in the housing for absorber units 54 of the absorbent product 80, the member for pulling out 62 extends from the aperture portion of the housing for the absorber unit 54 to outside of it, and then to the absorbent product main body 52 side, and the member for pulling out 62 is fixed on the absorbent product main body 52 with the adhesive layer 64. After the lower-most absorber 14 absorbs the discharged liquid to the limit of its absorbing capacity, the lower-most absorber 14 can be easily separated from the rest by pulling out this member for pulling out 62.

0145In addition to a surface sheet, a back sheet, and an absorber, the absorbent product of the present invention may include such members as gazette gathers, standing gathers, waist gathers, a fastening mechanism (tape, hook-and-loop fastner, etc.), and the wrapping tape mechanism used at the time of disposal. For these, conventional ones may be used.

0146The absorbent product of the present invention is suitable for use in baby diapers, adult incontinence diapers, sanitary napkins for women, etc.

0147When the absorbent product of the present invention is used as a diaper, it may be used for urine-disposing only or for both urine- and feces-disposing. When it is used for both urine- and feces-disposing, it is preferred that a urine-disposing portion extending from the center portion to the front body section, and a feces-disposing portion extending from the center portion to the back body section are provided, and that the surface sheet is provided only at the urine-disposing portion.

0148<figref idref="f0016">FIG. 20</figref> is a group of illustrative top views, each showing an example of a portion of an absorbent products.

0149In <figref idref="f0016">FIGs. 20 (A) through (D)</figref>, the upper side of the drawing is the front side of the absorbent product and the lower side of the drawing is the back side of the absorbent product.

0150In all of <figref idref="f0016">FIGs. 20 (A) through (D)</figref>, the surface sheet 10 is provided only in the urine-disposing portion at the front side of the absorber 14, and is not provided in the feces-disposing portion at the back side.

0151As for the structures that are different in the front side and the back side of the absorber, and as for the manufacturing method, one of the preferred embodiments is to use the technology suggested by the inventors of the present invention and described in <patcit id="pcit0020" dnum="JP6343660A"><text>JP 6-343660 A</text></patcit>. When this kind of structure is adopted, leg gathers or the like may be provided only at the front side.

0152Mixing of urine and feces is one of the causes of odor and rashes. A means to separate urine and feces, such as the urine-feces separator described in the <patcit id="pcit0021" dnum="JP7299092A"><text>JP 7-299092 A</text></patcit>, may be applied to the absorber of the present invention.

0153<figref idref="f0016">FIG. 21</figref> is an illustrative longitudinal section view showing an example of a portion of the absorbent product of the present invention. In <figref idref="f0016">FIG. 21</figref>, the left side of the drawing is the front side of the absorbent product and the right side of the drawing is the back side of the absorbent product.

0154In <figref idref="f0016">FIG. 21</figref>, the surface sheet 10 is provided only in the urine-disposing portion 34 at the front side of the absorber 14, and is not provided in the feces-disposing portion 36 at the back side. The surface sheet 10 is folded on a guide sheet 22 in the vicinity of the border between the urine-disposing portion 34 and the feces-disposing portion 36 of the absorber 14, and the folded portion can temporarily retain the urine to prevent the discharged liquid (urine) discharged at the urine-disposing portion from moving to the feces-disposing portion 36.

0155It is preferred that the absorbent product comprising the urine-disposing portion and the feces-disposing portion includes, at least at the feces-disposing portion, a liquid-impermeable or water-resistant urine backflow prevention sheet inside and/or on the upper surface thereof.

0156<figref idref="f0017">FIG. 22</figref> is an illustrative longitudinal section view showing an example of a portion of the absorbent product of the present invention. In <figref idref="f0017">FIG. 22</figref> the left side of the drawing is the front side of the absorbent product and the right side of the drawing is the back side of the absorbent product.

0157The absorbent product of the present invention shown in <figref idref="f0017">FIG. 22</figref> includes, at the feces-disposing portion 36, a liquid-impermeable or water-resistant urine backflow prevention sheet 38 inside the absorber 14. This urine backflow prevention sheet 38 is explained below.

0158In case the absorbent product does not include the urine backflow prevention sheet 38 as shown in <figref idref="f0016">FIG. 21</figref>, the surface sheet 10 can prevent the urine from moving on the upper side of the absorber 14 from the urine-disposing portion 34 to the feces-disposing portion 36, but the urine absorbed from the lower side of the absorber 14 can sometimes penetrate to the upper side of the absorber 14, reaching the surface of the upper side of the feces-disposing portion 36. In other words, the urine sometimes flows back. When this occurs, the effect of separating the urine and the feces disappears, and problems such as dirtying the buttocks and developing of diaper rashes can take place.

0159In contrast to this, in case the absorbent product includes the urine backflow prevention sheet 38 as shown in <figref idref="f0017">FIG. 22</figref>, the surface sheet 10 prevents the urine from moving on the upper side of the absorber 14 from the urine-disposing portion 34 to the feces-disposing portion 36, and in addition to this, even if the urine absorbed from the lower side of the absorber 14 penetrates to the upper side of the absorber 14, because a liquid-impermeable or water-resistant urine backflow prevention sheet 38 is provided inside the absorber 14, the urine will be prevented from reaching the surface of the upper side of the feces-disposing portion 36. In other words, the urine is prevented from flowing back. The desirable result of being free from the above problems is obtained.

0160There is no limit in particular to the material, structure, etc. of the urine backflow prevention sheet 38, as long as it is liquid-impermeable or water-resistant, and the film similar to the aforementioned surface sheet 10 and the back sheet 12, as well as a water-resistant nonwoven fabric may be used. In this specification, "water-resistant" means the characteristic that does not allow the water to permeate at a pressure of 9.6.807 x 10² Pa (100mm H₂O) or lower. It is preferred that the water-resistant nonwoven fabric has water resistance at a pressure of 1.961 x 10² Pa (200mm H₂O) or lower.

0161It is preferred that the urine backflow prevention sheet 38 is provided in a manner covering at least the feces-disposing portion 36 in the anteroposterior direction of the absorber 14 as described in <figref idref="f0017">FIG. 22</figref>. Furthermore, also in the left-to-right direction of the absorber 14, it is preferred that it covers the feces-disposing portion 36 to prevent the urine from reaching the surface of the upper side of the absorber 14.

0162The urine backflow prevention sheet 38 is provided inside the absorber 14 in <figref idref="f0017">FIG. 22</figref>, but it can also be provided on the surface of the feces-disposing portion 36, as well as at both of the above. Furthermore, plural sheets may be provided. There is no limit in particular to the method of providing the urine backflow prevention sheet 38 inside the absorber 14. If, for example, the absorber 14 is composed of laminating plural number of highly water-absorbing sheets, the urine backflow prevention sheet 38 may be held in between these highly water-absorbing sheets.

0163As mentioned above, the absorbent product of the present invention is significantly different from the conventional absorbent products in the way a part of or all of the urine supplied to the surface sheet moves downward. This will be explained further in detail.

0164<figref idref="f0017">FIG. 23</figref> is a cross-section view explaining the behavior of the urine when it is supplied to an absorbent product. In <figref idref="f0017">FIG. 23</figref>, only the absorber 14 and the sheet fully covering it in a left-to-right direction (this sheet is the liquid-permeable top sheet 11 in the conventional absorbent product, and is the liquid-impermeable surface sheet 10 in the absorbent product of the present invention) are shown.

0165The total amount of urine supplied to the sheet 10 or sheet 11 is denoted by Q, the total amount of the discharged liquid absorbed from the lateral surfaces or the lower surface by Q₁, and the total amount of the discharged liquid absorbed from the upper surface by Q₂ (provided that Q = Q₁ + Q₂).

0166In the conventional absorbent product, because nearly total amount of the urine supplied to the top sheet 11 passes through the top sheet 11 and absorbed by the absorber 14, most commonly Q₁ is approximately 1 to 10%, Q₂ is approximately 99 to 90%, and Q₁/Q₂ is approximately 0.01 to 0.1.

0167In contrast to this, in an embodiment of the absorbent product of the present invention wherein the surface sheet 10 fully covers the upper surface of the absorber 14 (for example, the absorbent product shown in <figref idref="f0005">FIGs. 7 (A) and (B)</figref>), because nearly the total amount of the urine supplied to the surface sheet 10 moves on the upper surface of the surface sheet 10 to the lower side of the absorber 14 via the end portions of the surface sheet 10, most commonly Q₁ is approximately 90 to 99%, Q₂ is approximately 10 to 1%, and Q₁/Q₂ is approximately 9 to 99.

0168Furthermore, in an embodiment of the absorbent product of the present invention wherein the surface sheet 10 covers a portion of the upper surface of the absorber 14 (for example, the absorbent product shown in <figref idref="f0005">FIGs. 7 (C) through (G)</figref>), because a part of the urine supplied to the surface sheet 10 moves on the upper surface of the surface sheet 10 to the lower side of the absorber 14 via the end portions of the surface sheet 10 and the remaining amount is absorbed directly from the upper surface of the absorber 14 with the portion thereof being exposed, though it depends on the design, Q₁, is approximately 50 to 70%, Q₂ is approximately 50 to 30%, and Q₁/Q₂ is approximately 1.0 to 2.5, for example.

0169As described above, the absorbent product of the present invention is significantly different from the conventional absorbent products in terms of its discharged-liquid-absorbing mechanism, and as a result, prevention of absorbing rate from lowering with the elapse of time and reduction of the re-wet amount are realized.

0170Hereinafter, the effect of the present invention will be explained further in detail by using the Examples.

Examples

1. Absorbing rate and re-wet amount of absorbent products

(1) Preparation of absorbent products

(Example 1)

0171The absorber was taken from a commercially available diaper, Kao Corporation's Merries, with a top sheet adhered thereto.

0172As shown in <figref idref="f0018">FIG. 24</figref>, the absorber 14 taken out of the diaper was turned upside down and was covered with an air-permeable PE film (manufactured by Tokuyama Corp., in a thickness of 20µm) used as a back sheet in commercially available diapers, which was used here to function as the liquid-impermeable surface sheet 10.

0173The upper surface, lateral surfaces and a portion of the lower surface of the absorber 14 were covered with a porous PE film (manufactured by Tredeger Co. and marketed as "T10650-1 TEC") which was used here to function as the guide sheet 22.

0174Furthermore, the absorber was covered with an air-permeable PE film (manufactured by Tokuyama Corp., in a thickness of 20µm) used as a back sheet in commercially available diapers, which was used here to function as the liquid-impermeable back sheet 12, and the absorbent product 90 was obtained.

(Example 2)

0175By the same method used in Example 1, except that Unicharm Corporation's Mamypoko-Cotton was used here as a commercially available diaper, the absorbent product 90 was obtained.

(Example 3)

0176By the same method used in Example 1, except that a prototype diaper using MegaThin (a highly water-absorbing sheet), an absorber manufactured by Japan Absorbent Technology Institute, was used here instead of a commercially available diaper, the absorbent product 90 was obtained.

0177Note that Kao Corporation's Merries, Unicharm Corporation's Mamypoko-Cotton, and a prototype diaper using MegaThin, the absorber manufactured by Japan Absorbent Technology Institute were used as they are as Comparative Examples 1 through 3 for measuring the absorbing capacity and re-wet amount, as hereinafter described.

(2) Measuring of absorbing capacity

0178As described below, the absorbing capacity of each absorber of the 2 types of commercially available diapers and one prototype diaper used in the Examples 1 through 3 was measured.

0179The diapers whose weights were measured beforehand were soaked in a sodium chloride solution of 0.9wt% for 30 minutes. After that, the diapers were taken out of the solution and kept in the condition of just being taken out of the solution for 30 seconds and drained. They were placed on a wire-mesh drainer with their top sheet facing down, an acrylic plate was placed on top of them to apply load to the absorbers in their entirety, and furthermore a weight (10kg) was put on top of the acrylic plate, after which they were left to stand for 20 minutes, and then drained. After that, they were weighed, and the increased weight was defined as the absorbing capacity. (The specific gravity of the sodium chloride solution was assumed to be 1.) The measurement was made under the condition of n=2.

0180The absorbing capacity of the absorber of Kao Corporation's Merries was 707mL, that of Unicharm Corporation's Mamypoko-Cotton was 606mL, and of that of a prototype diaper using MegaThin, the absorber manufactured by Japan Absorbent Technology Institute was 756mL.

(3) Measuring of absorbing rate

0181The absorbing rate of each of the absorbent products of Examples 1 through 3 and Comparative Examples 1 through 3 was measured as described below.

0182As shown in <figref idref="f0018">FIG. 25</figref>, a liquid-supplying plate (made of plastic and 7.5cm x 10cm in size) 92, comprising a cylindrical liquid-supplying portion with 2.0cm inside diameter, and a weight 94 positioned in the periphery of the liquid-supplying portion, was placed in the center of the upper surface of the absorbent product 90, and a load of 6.895 x 10²Pa (0.1psi) was applied. Note that <figref idref="f0018">FIG. 25 (A)</figref> is a perspective view and <figref idref="f0018">FIG. 25 (B)</figref> is a longitudinal-section view.

0183100mL sodium chloride solution of 0.9wt% was supplied to the liquid-supplying portion, and the time until it was visually confirmed that the sodium chloride solution inside the liquid-supplying portion had disappeared was measured. This time-measuring exercise was repeated three times in such a manner that the respective supplies of the liquid began in every 10 minutes.

0184The results are shown in Table 1. <tables id="tabl0001" num="0001"><img file="EP1570824B1_D0001.tif" /></tables>

0185As evident in Table 1, the absorbent products of the present invention (Example 1 through 3) had dramatically higher absorbing rates than the conventional absorbent products (Comparative Examples 1 through 3), and furthermore their absorbing rates hardly changed with the elapse of time. Especially, when a mixture of SAP and fluffy pulp was used as an absorber, conventionally, the absorbing rate was low and the change of the absorbing rate with the elapse of time was significant (Comparative Examples 1 and 2), but they were markedly improved in the absorbent products of the present invention (Examples 1 and 2).

(4) Measuring of re-wet amount

(a) Re-wet amount per 100mL of supplied liquid

0186The re-wet amount of the absorbent products per 100mL of supplied liquid in Examples 1 and 3 and Comparative Examples 1 and 3 was measured in the way described below.

0187Under no load, 100mL of sodium chloride solution of 0.9wt% was added dropwise at the rate of 13mL/sec onto the center of the upper surface of the absorbent product by using a burette positioned at 10mm above the surface. Five minutes later from the start of dripping the solution, a paper filter whose weight was measured beforehand was placed in such a way that its center matched the spot where the solution was added dropwise, and a weight was put on top of it to apply a load or 6.895 x 10² Pa (0.1psi). Three minutes later, the weight was removed, the paper filter was weighed and the measurements of the re-wet amount per 100mL of supplied liquid. This process was repeated a total of seven times in such a manner that dropwise addition of the solution began in every 10 minutes.

0188The results are shown in Table 2. <tables id="tabl0002" num="0002"><img file="EP1570824B1_D0002.tif" /></tables>

(b) Re-wet amount when the amount of liquid equivalent to

01891/2 of the absorbing capacity is supplied (when 50% is supplied)

0190The re-wet amount of the absorbent products in each Examples 1 through 3 and Comparative Examples 1 through 3 was measured when the amount of liquid equivalent to 1/2 of the absorbing capacity was supplied, as described below.

0191Under no load, 100mL of sodium chloride solution of 0.9wt% was added dropwise at a rate of 13mL/sec onto the center of the upper surface of the absorbent product by using a burette positioned 10mm above the surface. This was repeated in such a manner that the dropwise addition of the solution began in every 5 minutes, until the amount of the solution added dropwise reached an amount equivalent to 1/2 of the absorbing capacity (350mL in Examples 1 and 3 and Comparative Examples 1 and 3, and 300mL in Example 2 and Comparative Example 2). Note that when 1/2 of absorbing capacity was 350mL, the amount of sodium chloride solution added dropwise at the fourth time was 50mL. Five minutes later from the beginning of dropwise addition of the solution of the last round, a paper filter whose weight was measured beforehand was placed in such a way that its center matched the spot where the solution was being added dropwise, and a weight was put on top of it to apply a load of 6.895 x 10² Pa (0.1psi). Three minutes later, the weight was removed, the paper filter was weighed and the measurements of the re-wet amount when an amount of liquid equivalent to 1/2 of the absorbing capacity is supplied were made.

0192The re-wet amount was measured three times in this manner, and the average value was calculated.

0193Furthermore, the weight was changed to apply a load of 3.448 x 10^2pa (0.5 psi) and the re-wet amount when the amount of liquid equivalent to 1/2 of the absorbing capacity is supplied was measured three times in the same method and the average value was obtained.

0194The results are shown in Table 3. <tables id="tabl0003" num="0003"><table frame="all"><title>Table 3</title><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="29mm" /><colspec colnum="3" colname="col3" colwidth="20mm" /><colspec colnum="4" colname="col4" colwidth="30mm" /><colspec colnum="5" colname="col5" colwidth="20mm" /><colspec colnum="6" colname="col6" colwidth="30mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><thead><row><entry valign="top">Load (psi)</entry><entry valign="top">Comparative Example 1</entry><entry valign="top">Example 1</entry><entry valign="top">Comparative Example 2</entry><entry valign="top">Example 2</entry><entry valign="top">Comparative Example 3</entry><entry valign="top">Example 3</entry></row></thead><tbody><row><entry align="char" char="." charoff="10">0.1</entry><entry align="char" char=".">24.1</entry><entry align="char" char="." charoff="10">0.5</entry><entry align="char" char=".">34.1</entry><entry align="char" char="." charoff="10">0.1</entry><entry align="center">3.3</entry><entry align="char" char="." charoff="10">0.1</entry></row><row><entry align="char" char="." charoff="10">0.5</entry><entry align="char" char=".">37.3</entry><entry align="char" char="." charoff="10">0.6</entry><entry align="char" char=".">39.3</entry><entry align="char" char="." charoff="10">0.8</entry><entry align="center">10.0</entry><entry align="char" char="." charoff="10">1.5</entry></row></tbody></tgroup></table></tables>

0195As evident in Table 2 and Table 3, the absorbent products of the present invention (Examples 1 through 3) had a dramatically smaller re-wet amount than the conventional absorbent products (Comparative Examples 1 through 3), and furthermore their re-wet amount hardly changed with the elapse of time.

2. Characteristics of the absorbent product including a plural number of absorber units

(1) Preparation of absorbent products

(Example 4 and Comparative Examples 4 and 5)

0196The absorbent products 100 including a plural number of absorber units as shown in <figref idref="f0019">FIG. 26</figref> were made. As the absorbent product main bodies 52, sewn stockinet underpants for women (manufactured by Gunze Ltd.), to which the housing for the absorber, including the leak-proof back sheet, was attached, were used. <figref idref="f0019">FIG. 26 (A)</figref> is a front view and <figref idref="f0019">FIG. 26 (B)</figref> is a top view. In <figref idref="f0019">FIG. 26 (A)</figref>, this side of the drawing is the front side of the absorbent product.

0197The absorbent products 100 were obtained by housing the laminates shown in <figref idref="f0021">FIG. 28</figref>, which are obtained by laminating 3 pieces of each absorber unit shown in <figref idref="f0020">FIG. 27</figref>, in the housing for the absorber units 54 in the absorbent product main body 52. All views shown in <figref idref="f0020">FIG. 27</figref> and <figref idref="f0021">FIG. 28</figref> are cross-section views.

0198The absorber unit used in Example 4, as shown in <figref idref="f0020">FIG. 27 (A)</figref>, was obtained by covering with the liquid-impermeable surface sheet 10, the upper surface, lateral surfaces and a portion of lower surface of the absorber 14 made by folding in half the super absorbent sheet comprising a SAP layer 102 on one side of it, in such a manner that the SAP surface faces inside of the fold.

0199The absorber unit used in Comparative Example 4, as shown in <figref idref="f0020">FIG. 27 (B)</figref>, was obtained by covering with the liquid-permeable sheet 104, the lower surface, lateral surfaces and a portion of the upper surface of the absorber 14 same as the one used in Example 4.

0200The absorber unit used in Comparative Example 5, as shown in <figref idref="f0020">FIG. 27 (C)</figref>, was obtained by covering with the liquid-permeable sheet 104, instead of the liquid-impermeable surface sheet 10 used in Example 4.

0201In the Example 4, three pieces of the absorber unit shown in <figref idref="f0020">FIG. 27 (A)</figref> were laminated and used (from the top, each layer is called the first layer, second layer, and the third layer). The areas between the first layer and the second layer, as well as between the second layer and the third layer, were adhered in a quick and simple manner by providing a hot-melt layer 106 at their left and right end portions. The upper surface, lateral surfaces and most of the lower surface of the laminate of the three absorber units were covered with the guide sheet 22 and used.

0202In the Comparative Example 4, three pieces of the absorber unit shown in <figref idref="f0020">FIG. 27 (B)</figref> were laminated and used (from the top, each layer is called the first layer, second layer, and the third layer). The areas between the first layer and the second layer, as well as between the second layer and the third layer, were adhered in a quick and simple manner by providing a hot-melt adhesive layer 106 at their left and right end portions.

0203In the Comparative Example 5, three pieces of the absorber unit shown in <figref idref="f0020">FIG. 27 (C)</figref> were laminated and used (from the top, each layer is called the first layer, second layer, and the third layer). The areas between the first layer and the second layer, as well as between the second layer and the third layer, were adhered in a quick and simple manner by providing a hot-melt adhesive layer 106 at their left and right end portions.

(2) Absorbability Test

0204The absorbent products of Example 4 and Comparative Examples 4 and 5 were actually put on a wearer, and the wearer urinated twice, each time in a standing position. The second urination was performed after one predetermined layer of the absorber was removed following the first urination. The amount of urine discharged each time was about 200mL. The amount absorbed by each layer of the absorber after each urination was measured and the rate of utilization was calculated.

0205The results after the first urination of Example 4 are shown in Table 4. <tables id="tabl0004" num="0004"><table frame="all"><title>Table 4</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="47mm" /><colspec colnum="3" colname="col3" colwidth="52mm" /><colspec colnum="4" colname="col4" colwidth="35mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">Actual Amount Absorbed (mL)</entry><entry valign="top">Designed Absorption Amount (mL)</entry><entry valign="top">Rate of Utilization (%)</entry></row></thead><tbody><row><entry>1^st Layer</entry><entry align="center">0</entry><entry align="center">200</entry><entry align="center">0</entry></row><row><entry>2nd Layer</entry><entry align="center">0</entry><entry align="center">200</entry><entry align="center">0</entry></row><row><entry>3^rd Layer</entry><entry align="center">180</entry><entry align="center">200</entry><entry align="center">90</entry></row></tbody></tgroup></table></tables>

0206As shown in Table 4, only the third layer, which was the lower-most layer, absorbed the urine, and the first and the second layers did not absorb urine. Also, according to visual observation, while absorption took place uniformly in nearly the entire surface area of the third layer, no wetting was observed in the first and second layers.

0207After the first urination, the third layer of the absorber was removed from the housing for the absorber units. At this time, the first layer and the second layer remained covered with the guide sheet in the housing for the absorber units. In other words, the removal of the third layer of the absorber was carried out easily, without any problems.

0208The results after the second urination of Example 4 are shown in Table 5. <tables id="tabl0005" num="0005"><table frame="all"><title>Table 5</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="37mm" /><colspec colnum="3" colname="col3" colwidth="37mm" /><colspec colnum="4" colname="col4" colwidth="40mm" /><colspec colnum="5" colname="col5" colwidth="35mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">The 1^st Actual Amount Absorbed (mL)</entry><entry valign="top">The 2^nd Actual Amount Absorbed (mL)</entry><entry valign="top">Designed Absorption Amount (mL)</entry><entry valign="top">Rate of Utilization (%)</entry></row></thead><tbody><row><entry>1^st Layer</entry><entry align="center">0</entry><entry align="center">10</entry><entry align="center">200</entry><entry align="center">5</entry></row><row><entry>2^nd Layer</entry><entry align="center">0</entry><entry align="center">210</entry><entry align="center">200</entry><entry align="center">105</entry></row></tbody></tgroup></table></tables>

0209As shown in Table 5, the second layer, which was the lower-most layer, absorbed the urine almost to the limit of its absorbing capacity, and the first layer absorbed the amount which was not absorbed by the second layer.

0210The second layer of the absorber was removed after the second urination. The removal of the second layer also was carried out easily, without any problems.

0211The results after the first urination of Comparative Example 4 are shown in Table 6. <tables id="tabl0006" num="0006"><table frame="all"><title>Table 6</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="47mm" /><colspec colnum="3" colname="col3" colwidth="52mm" /><colspec colnum="4" colname="col4" colwidth="35mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">Actual Amount Absorbed (mL)</entry><entry valign="top">Designed Absorption Amount (mL)</entry><entry valign="top">Rate of Utilization (%)</entry></row></thead><tbody><row><entry>1^st Layer</entry><entry align="center">95</entry><entry align="center">200</entry><entry align="char" char="." charoff="11">47.5</entry></row><row><entry>2^nd Layer</entry><entry align="center">65</entry><entry align="center">200</entry><entry align="char" char="." charoff="11">32.5</entry></row><row><entry>3^rd Layer</entry><entry align="center">35</entry><entry align="center">200</entry><entry align="char" char="." charoff="11">17.5</entry></row></tbody></tgroup></table></tables>

0212As shown in Table 6, the first layer, which was the upper-most layer, absorbed about one half of the urine, and the second and the third layers also absorbed some urine. Furthermore, according to the visual observation, absorption took place on the entire surface, except for about 1/5 of the total area located on the front side. The thickness in the back side, however, was large, more precisely it was 1.5cm. This was assumed to be the result of temporarily retaining the urine which was not absorbed first and then gradually absorbing it later. In the second layer, absorption took place to a level that thickened the absorber to about 1cm, in an area equivalent to about 1/3 of the total area located on the back side. Furthermore, some portions on the front side were assumed to be penetrated with urine from the first layer. In the third layer, absorption took place to a level that thickened the absorber to about 1cm, in an area equivalent to about 1/3 of the total area located on the back side.

0213After the first urination, the first layer of the absorber was removed from the housing for the absorber units. At this time, because it was impossible to remove the first layer only, and the second layer and the third layer also came out, the first layer was separated from the rest and the second and the third layers were put back to the housing for the absorber units. In other words, the removal of the first layer was difficult.

0214The results after the second urination in Comparative Example 4 are shown in Table 7. <tables id="tabl0007" num="0007"><table frame="all"><title>Table 7</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="37mm" /><colspec colnum="3" colname="col3" colwidth="37mm" /><colspec colnum="4" colname="col4" colwidth="40mm" /><colspec colnum="5" colname="col5" colwidth="35mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">The 1^st Actual Amount Absorbed (mL)</entry><entry valign="top">The 2^nd Actual Amount Absorbed (mL)</entry><entry valign="top">Designed Absorption Amount (mL)</entry><entry valign="top">Rate of Utilization (%)</entry></row></thead><tbody><row><entry>2^nd Layer</entry><entry align="center">65</entry><entry align="center">125</entry><entry align="center">200</entry><entry align="center">95</entry></row><row><entry>3^rd Layer</entry><entry align="center">35</entry><entry align="center">75</entry><entry align="center">200</entry><entry align="center">55</entry></row></tbody></tgroup></table></tables>

0215As shown in Table 7, the second layer, which was the upper-most layer, absorbed about 2/3 of the urine and the third layer also absorbed some.

0216After the second urination, the second layer of the absorber was removed from the housing for the absorber units, but the removal of the second layer also was difficult.

0217The results after the first urination in Comparative Example 5 are shown in Table 8. <tables id="tabl0008" num="0008"><table frame="all"><title>Table 8</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="47mm" /><colspec colnum="3" colname="col3" colwidth="52mm" /><colspec colnum="4" colname="col4" colwidth="35mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">Actual Amount Absorbed (mL)</entry><entry valign="top">Designed Absorption Amount (mL)</entry><entry valign="top">Rate of Utilization (%)</entry></row></thead><tbody><row><entry>1^st Layer</entry><entry align="center">60</entry><entry align="center">200</entry><entry align="center">30</entry></row><row><entry>2^nd Layer</entry><entry align="center">60</entry><entry align="center">200</entry><entry align="center">30</entry></row><row><entry>3^rd Layer</entry><entry align="center">50</entry><entry align="center">200</entry><entry align="center">25</entry></row></tbody></tgroup></table></tables>

0218As shown in Table 8, absorption took place almost uniformly in the first through third layers. Therefore, continued use by removing one of the layers was unlikely. Because of this, the second urination was not performed.

0219Note that the "Designed Absorption Amount" in Tables 4 through 8 represents each absorber's absorbing capacity of the sodium chloride solution of 0.9wt% under a load of 0.5psi 3.448 x 10²Pa (0.5psi).

0220As evidenced by the above Examples, one of the preferred embodiments of the absorbent product of the present invention is that its re-wet amount measured under a load of 6.895.10² Pa (0.1psi), 5 minutes later from the beginning of the absorption, after having a sodium chloride solution of 0.9wt% in the amount equivalent to 50% of the absorbing capacity of the absorber absorbed in the absorber at 25°C under no load, is 5mL or less, or more preferably 2mL or less.

0221Furthermore, one of the preferred embodiments of the absorbent product of the present invention is that the absorber's absorbing capacity of sodium chloride solution of 0.9wt% is 300mL or more, and when saline is added to be absorbed by the absorber in the amount of 100mL each time in three separate additions under no load in every 10 minutes, an average re-wet amount after three additions is 5mL or less, and the standard deviation of the re-wet amount is 3mL or less; and when saline is added to be absorbed by the absorber in the amount of 100mL each time in three separate additions under a load of 6.895.10²Pa (0.1psi) in every 10 minutes, the mean absorption time of the three additions is 30 seconds or less, and the standard deviation of the absorption time is 2 seconds or less.

3. Characteristics of the absorbent products, including the backflow prevention sheet

0222The re-wet amount in the feces-disposing portion of the absorbent product without a backflow prevention sheet as shown in <figref idref="f0016">FIG. 21</figref> and the re-wet amount in the feces-disposing portion of the absorbent product with a backflow prevention sheet as shown in <figref idref="f0017">FIG. 22</figref> were compared. Both of these absorbent products were for both urine- and feces-disposing. Widths in the left-to-right direction of the surface sheet 10, absorber 14, guide sheet 22 and the backflow prevention sheet 38 were the same in these absorbent products.

0223As shown in <figref idref="f0022">FIG. 29</figref>, a liquid-supplying plate 92, comprising a cylindrical liquid-supplying portion with 2.0cm inside diameter, and a weight 94 positioned in the periphery of the liquid-supplying portion, was placed on a urine-disposing portion 34 of the absorbent product 14, and a load of 01psi was applied. At the same time, a paper filter 96 whose weight was measured beforehand was placed on a feces-disposing portion 36 of the absorbent product 14, and further an acrylic plate 98 was placed on it, and furthermore a weight was put on top of it to apply a load 6.895.10²Pa (0.1psi) on it.

0224100mL sodium chloride solution of 0.9wt% was supplied to the liquid-supplying portion, and 3 minutes later from the beginning of the supplying of the liquid, the paper filter was removed to be weighed. This exercise was repeated three times in such a manner that supplies of the liquid began in every 10 minutes.

0225The results are shown in Table 9. <tables id="tabl0009" num="0009"><table frame="all"><title>Table 9</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="49mm" /><colspec colnum="2" colname="col2" colwidth="18mm" /><colspec colnum="3" colname="col3" colwidth="52mm" /><colspec colnum="4" colname="col4" colwidth="49mm" /><thead><row><entry valign="top" /><entry valign="top" /><entry valign="top">Without Backflow Prevention Sheet</entry><entry valign="top">With Backflow Prevention Sheet</entry></row></thead><tbody><row><entry morerows="2">Re-wet Amount at Feces-disposing Portion (mL)</entry><entry>1^st Time</entry><entry align="char" char=".">0.5</entry><entry align="char" char="." charoff="4">0.0</entry></row><row><entry>2^nd Time</entry><entry align="char" char=".">1.8</entry><entry align="char" char="." charoff="4">0.1</entry></row><row><entry>3^rd Time</entry><entry align="char" char=".">2.9</entry><entry align="char" char="." charoff="4">0.7</entry></row></tbody></tgroup></table></tables>

0226As shown in Table 9, the re-wet amount at the feces-disposing portion was extremely small when the absorbent product for both urine- and feces-disposing included the backflow prevention sheet.

Industrial Applicability

0227The absorbent product of the present invention is suitable for use as a baby diaper, adult incontinence diaper, sanitary napkin for women, etc. because it is capable of preventing the absorbing rate of discharged liquid from significantly lowering with the elapse of time, and has a very small re-wet amount.