JP2004337386A - Absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent article which facilitates the recognition of visual changes from outside including discoloring due to urination. <P>SOLUTION: The absorbent article 1 has an absorbent 4 and a liquid-impermeable rear sheet 3. The absorbent 4 has an absorbing core 41 containing a high absorbability polymer and a shape holding sheet 42 covering the circumference thereof. A thin paper 43 is interposed between the shape holding sheet 42 and the rear sheet 3. A hydrophilic composition 10 visually changeable when contacting the moisture is contained at the specified part between the thin paper 43 and the rear sheet 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an absorbent article having a function of making a visual change before and after urination easy for an observer to understand, and for surely notifying a replacement time.
[0002]
Problems to be solved by the prior art and the invention
Until now, various types of disposable diapers having a function of notifying a replacement time when they become wet due to urination or the like have been proposed. For example, diapers containing a pH indicator that changes color when urine reaches the surface of the absorbent core opposite to the wearer contact surface are known (see Patent Documents 1 to 3). Also, a diaper containing an agent that changes color when wetted with water (Patent Document 4) is known.
[0003]
However, any of the techniques has a problem that the degree of discoloration is difficult to clearly recognize from outside. The reason for this is that since the agent that changes color is hydrophilic, when urine is sensed, the agent dissolves in the urine, causing bleeding and blurring of the color. Moreover, in order to sense urine, it is preferable to arrange a discoloring agent as close as possible to the absorbent core, so that when the agent is absorbed and diffused into the absorbent core, the color is more difficult to be recognized from the outside. . Also, since various patterns and the like are usually arranged on the diaper, the discolored portion is often arranged small so as not to impair the appearance of the entire diaper, and in such a case, the above phenomenon occurs. Then, the discoloration becomes more difficult to be recognized from the outside.
[0004]
[Patent Document 1]
JP-A-55-36326 [Patent Document 2]
JP-A-56-43402 [Patent Document 3]
JP-A-11-4852 [Patent Document 4]
JP-A-58-174601 [0005]
Therefore, an object of the present invention is to provide an absorbent article in which visual changes such as discoloration caused by urination are easily recognized from the outside.
[0006]
[Means for Solving the Problems]
The present invention is an absorbent article comprising an absorber and a liquid-impermeable back sheet on the side opposite to the wearer's skin contact surface of the absorber, wherein the absorber is a highly absorbent polymer Comprising an absorbent core and a shape-retaining sheet covering the periphery thereof, wherein thin paper is interposed between the shape-retaining sheet and the backsheet, and between the thin paper and the backsheet. The object has been achieved by providing an absorbent article containing a hydrophilic composition which changes visually when it comes into contact with moisture at a predetermined site.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. FIG. 1 shows a partially cutaway plan view of a disposable diaper as one embodiment of the present invention as viewed from a back sheet side. FIG. 2 is a sectional view taken along line II-II in FIG. In FIG. 2, the side of the back sheet 3 is drawn on the upper side. The diaper 1 has a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and an absorber 4 interposed between these two sheets 2, 3, and is formed substantially vertically. The absorber 4 is configured such that the periphery of the absorbent core 41 is covered with a shape-retaining sheet 42. The shape retention sheet 42 is used for the purpose of maintaining the shape retention of the absorbent core 41. An outer cover sheet 7 made of a nonwoven fabric is arranged on the outer surface (the side opposite to the absorber side) of the back sheet 3. The outer cover sheet 7 forms the outer edge of the diaper 1. The diaper 1 includes a crotch portion B, and a ventral portion C and a back portion A extending forward and backward from the crotch portion B. The back part A is a part located on the back side of the wearer when using the diaper. The abdominal part C is a part located on the abdomen of the wearer when using the diaper. Fastening tapes 8, 8 are provided on both left and right side edges of the back part A. The fastening tape 8 is fixed to a landing tape 9 provided on the exterior cover sheet 7 in the abdominal side C when the diaper is worn.
[0008]
The absorber 4 is sandwiched and fixed between the top sheet 2 and the back sheet 3. The waist portions 5 and 5 extending in the front-rear direction from the front and rear end edges of the absorber 4 and the leg portions 6 and 6 extending in the lateral direction from the left and right side edges are used to fit the diaper wearer to the wearer. The waist elastic member 51 and the leg elastic member 61 are provided. A three-dimensional guard is formed on each of the left and right sides in the longitudinal direction on the top sheet side of the diaper 1 (not shown). A solid guard elastic member is disposed at a free end of the solid guard to form a gather.
[0009]
As each of the members constituting the diaper 1 described above, those conventionally known in the art can be used without any particular limitation. For example, as the topsheet 2, a hydrophilic nonwoven fabric, a perforated film, or the like can be used. As the back sheet 3, a liquid impermeable film or the like can be used. As the absorbent core 41, a pile of fluff pulp and particles of a superabsorbent polymer can be used. Various elastomer materials can be used for the elastic members 61 and 71.
[0010]
Thus, in the disposable diaper 1 of the present embodiment, as shown in FIGS. 1 and 2, a thin paper 43 such as a hydrophilic tissue paper is interposed between the shape retaining sheet 42 and the back sheet 3. Further, between the thin paper 43 and the back sheet 3, a hydrophilic composition (hereinafter, referred to as a changing agent) 10 that changes visually when it comes into contact with moisture is included. In the present embodiment, the changing agent 10 is provided on the surface of the back sheet 3 facing the thin paper 43, and the changing agent 10 faces the thin paper 43. More specifically, a modifier 10 made of a hot melt composition in which a pH indicator (for example, bromophenol blue) or the like is mixed with the adhesive component is applied to the thin paper facing surface of the back sheet 3 by a method described later, and the thin paper facing surface is applied. Above, the absorbent body 4 in which the thin paper 43 and the absorbent core 41 are covered by the shape-retaining sheet 42 is placed. In the present invention, "visually changing" is a concept including a case where a color changes before and after contact with moisture, a case where a color disappears upon contact with moisture, and a case where a color appears upon contact with moisture. It is. The changing agent 10 of the present embodiment corresponds to the case where the color changes before and after contact with moisture.
[0011]
In the present embodiment, the changing agent 10 is provided linearly across the back part A, the crotch part B, and the abdomen part C of the diaper at the center in the diaper width direction. More specifically, three elongated lines are provided in parallel in the diaper width direction. As in the disposable diaper 1 of the present embodiment, the presence of the changing agent 10 in the crotch portion B allows the changing agent 10 to visually change when urine is absorbed by the absorber 4 and reaches the back sheet 3. Then, it is possible to notify the time of replacement of the diaper 1.
[0012]
In the disposable diaper of the present invention, the thin paper 43 is interposed between the shape-retaining sheet 42 and the back sheet 3, and the point that the changing agent 10 is contained between the thin paper 43 and the back sheet 3 is the largest. There are features. More specifically, in the disposable diaper 1 of the present embodiment, as shown in FIG. 1, all the lines of the three changing agents 10 are present so as to overlap the thin paper 43 over the entire length of the diaper in the longitudinal direction. ing. By adopting such a configuration, it is possible to enhance the recognizability of a visual change for notifying the time of replacing the diaper 1.
[0013]
In the disposable diaper of the present invention, the mechanism for enhancing the recognizability of a visual change is presumed as the following (1) to (3).
(1) The urine reaches the place where the changing agent 10 is present, and the changing agent 10 is discolored. At the same time, the changing agent 10 elutes or disperses in urine and moves into the thin paper 43 in contact with the back sheet 3. Although the changing agent 10 tends to transfer a little amount to the shape retaining sheet 42 existing on the absorbent core 41 side than the thin paper 43, most of the agent is fixed to the thin paper 43. Do not migrate.
(2) The shape-retaining sheet 42 is already wet at the stage where urine migrates to the back sheet 3. Therefore, it is in a state where it is difficult to absorb the liquid more positively. This is also considered to be one reason that the change agent 10 hardly migrates to the shape retaining sheet 42.
(3) The presence of the shape-retaining sheet 42 prevents the thin paper 43 in contact with the changing agent 10 from directly contacting the absorbent core 41. This prevents the change agent 10 from being diffused in the plane direction by the absorbent core 41 and lightening the color of the change agent 10.
[0014]
As described above, according to the present invention, (a) the thin paper 43 is interposed between the back sheet 3 and the shape-retaining sheet 42, whereby the changing agent 10 is fixed to the thin paper 43, and (b) the shape-retaining By interposing the sheet 42 between the absorbent core 41 and the thin paper 43, the tendency of the change agent 10 to migrate to the absorbent core 41 is reduced. It is presumed that by these, the recognizability of the visual change by the changing agent 10 could be improved.
[0015]
It is preferable that the thin paper 43 is hydrophilic in order to achieve the above-described effects more reliably. Further, the basis weight of the thin paper is preferably 5 to 30 g / cm ² . In particular, in consideration of ensuring the fixation of the changing agent 10 to the thin paper 43 and making the urine reach the back sheet 3 at an appropriate speed, the basis weight of the thin paper 43 is 10 to 20 g / cm ^2. Is more preferable. From the same viewpoint, the thickness of the thin paper 43 is preferably from 0.05 to 1 mm, and particularly preferably from 0.1 to 0.5 mm, since a feeling of strangeness is less likely to occur in the crotch portion B.
[0016]
In the present embodiment, all the lines of the changing agent 10 are provided so as to overlap with the thin paper 43 over the entire area in the diaper longitudinal direction. However, in order to attain the object of the present invention at a minimum, the changing agent is It is sufficient that a part of the ten lines is provided so as to overlap the thin paper 43. The reason for this is that since the urination part of the wearer is present in the crotch part B, the amount of urination in that part is most important in knowing the time to change the diaper 1.
[0017]
It is preferable that the thin paper 43 has low transparency and high whiteness so that the visual change of the changing agent 10 can be clearly recognized from the outside of the diaper. The transparency is preferably 20% or less. The whiteness is preferably such that the b * value of the color coordinate index of the L * a * b * color system (CIE1976) is 3 to a minus value, particularly 1 to -5, particularly 0 to -5. The thin paper 43 having such transparency and whiteness can be obtained, for example, by using bleached pulp or by adding a filler to the thin paper. The absorbent core 41 preferably has high whiteness, but in the present invention, since the thin paper 43 is interposed between the absorbent core 41 and the back sheet 3, the color of the absorbent core 41 (particularly, (Yellowish) is less likely to appear, and therefore, there is an advantage that the visual change of the changing agent 10 can be easily recognized from outside the diaper even if it has a certain degree of color.
[0018]
The b * value is measured by a color difference meter. In the present invention, using a handheld spectral color difference meter NF777 (trade name) manufactured by Nippon Denshoku Industries Co., Ltd., measurement of illumination condition C, viewing angle condition 2 °, front light receiving condition = 0/45 °, and light beam diameter φ10 mm was performed. Under the conditions, it is obtained by measuring the reflected light in a state where a plurality of thin papers 43 are stacked on the back side of the measurement sample so as to have a thickness of 5 mm or more.
[0019]
The shape-retaining sheet 42 and the thin paper 43 are bonded to each other with a hydrophobic pressure-sensitive adhesive (for example, a hot-melt pressure-sensitive adhesive) in at least a part of an overlapping portion of the diaper 1 with a region where the changing agent 10 exists in the thickness direction of the diaper 1. It is preferred that This prevents urine from diffusing in the diaper width direction in the thin paper 43, thereby suppressing color bleeding due to diffusion of the changing agent 10. The position where the hydrophobic pressure-sensitive adhesive is provided is preferably located outside the center in the diaper width direction in the region where the changing agent 10 is present.
[0020]
In the present embodiment, by providing the changing agent 10 from the abdominal part C to the dorsal part A along the diaper longitudinal direction, the visual change of the changing agent 10 in the crotch part B can be changed. It is possible to clearly recognize by comparing with the back part A and the abdominal part C, which are relatively difficult to occur. Moreover, since a plurality of the changing agents 10 are arranged in a narrow band shape in the width direction of the diaper (three in the present embodiment), the visual change is more easily recognized.
[0021]
The shape-retaining sheet 42 is used to maintain the shape of the absorbent core 41 containing the particles of the superabsorbent polymer, and covers the periphery of the absorbent core 41, that is, the upper and lower surfaces and both side surfaces. As such a sheet, any liquid-permeable sheet can be used without particular limitation. For example, in the present embodiment, a hydrophilic nonwoven fabric is used. Since the texture of the nonwoven fabric is soft, the use of the nonwoven fabric is advantageous in that it hardly gives the wearer a stiff feel. In the present embodiment, since the thin paper 43 is provided only on the back sheet side, it can be said that the thin paper 43 does not give a feeling of stiffness on the side in contact with the wearer's skin, which is a more preferable form. It is preferable that the shape retention sheet 42 has a basis weight of 5 to 20 g / m ² from the viewpoint of achieving both good shape retention properties and a feeling of wearing and preventing leakage of polymer particles. In particular, it is preferably 5 to 15 g / m ² from the viewpoint of more effectively preventing the change agent 10 from migrating from the thin paper 43.
[0022]
The nonwoven fabric used for the shape-retaining sheet 42 may be one using fibers usually used for absorbent articles. As a fiber that can be used, for example, a single fiber composed of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, polyacrylic acid, or polyamide, a single fiber composed of a semi-synthetic fiber such as rayon or Tencel, or a material thereof. Core-sheath type or side-by-side type composite fibers composed of a combination of two or more of the above. The fibers constituting the nonwoven fabric may be only one kind or two or more kinds. Each fiber may be in the form of either a long fiber or a short fiber. The fineness of the fiber is preferably 0.5 to 9 dtex, particularly preferably 1 to 5.6 dtex. Specific examples of the nonwoven fabric made of such fibers include an air-through nonwoven fabric, a spunbonded nonwoven fabric, a spunlace nonwoven fabric, and a resin-bonded nonwoven fabric.
[0023]
The absorbent core 41 of the present embodiment can include fluff pulp, other hydrophilic fibers, hot melt fibers, and the like, in addition to the superabsorbent polymer. In this case, the absorbent core 41 is used in a form in which the superabsorbent polymer is dispersed between the fibers of the pile of fibers or in a form in which the superabsorbent polymer is sandwiched between layers of the pile of fibers. . In any case, it is preferable that the absorbent core 41 is formed by pressing.
[0024]
Examples of the superabsorbent polymer include sodium polyacrylate, (acrylic acid-vinyl alcohol) copolymer, sodium polyacrylate crosslinked product, (starch-acrylic acid) graft polymer, (isobutylene-maleic anhydride) copolymer and Other saponified compounds, potassium polyacrylate, cesium polyacrylate and the like can be mentioned. By providing a cross-link density gradient on the surface of the particles of the superabsorbent polymer or by making the particles non-spherical in irregular shape, gel blocking can be suppressed and liquid permeability can be increased. In this way, the urine can reach the changing agent 10 at an appropriate speed.
[0025]
As the fibers constituting the absorbent core 41, in addition to fluff pulp, rayon, cotton, hydrophilic fibers such as cellulose acetate, polyethylene, polyolefin-based fibers such as polypropylene, polyester, condensed fibers such as polyamides, vinyl chloride, Fibers of a vinyl monomer polymer such as vinyl acetate may be used. In particular, when a thin absorber (5 mm or less) is used, in addition to these fibers, a substance for enhancing the shape retention of the absorbent core 41, for example, water-soluble and weakly hydrophobic, impairs the absorption performance. The absorbent core 41 may be impregnated with a hot melt adhesive that is not used.
[0026]
Next, the changing agent 10 used in the present invention will be described. The change agent is a hydrophilic composition containing a substance that changes visually upon contact with moisture (hereinafter, referred to as a discoloration substance). Examples of the color changing substance include a pH indicator and the like. For example, known inks or indicators can be used. When the absorbent article is a disposable diaper as in the present embodiment, it is preferable to use a pH indicator whose color changes before and after contact with urine. For example, bromophenol blue, methyl orange, Alizan S, bromocresol green, methyl red, bromocresol purple, resazurin, and the like that changes color at a pH of 3 to 7 are preferable.
[0027]
The change agent 10 needs to be stably immobilized on the surface of the back sheet 3 and / or the thin paper 43 until it comes into contact with moisture. As a method of realizing such fixation, a method of applying the changing agent 10 as a hydrophilic composition obtained by mixing a color changing substance and an adhesive substance on the surface of the back sheet 3 or the thin paper 43 is simple and reliable. is there. As the tacky substance, a substance having hydrophilicity is preferable from the viewpoint of compatibility with the discoloration substance. Such a substance includes, for example, a hydrophilic polymer that functions as an adhesive between the thin paper 43 and the back sheet 3 before coming into contact with moisture. Examples of the hydrophilic polymer include polyethylene glycol (PEG), polypropylene glycol (PPG), polyvinyl alcohol (PVA), polyamide, and vinylpyrrolidone homopolymer. The number average molecular weight of these hydrophilic polymers is preferably from 1,000 to 50,000, particularly preferably from 2,000 to 20,000, from the viewpoint of providing reliable immobilization.
[0028]
The changing agent 10 is recognized from the outside of the diaper through the back sheet 3. Therefore, it is preferable to use a material having high transparency as the back sheet 3 in order to improve visibility. However, if the transparency is too high, excrement may be seen through from the outside of the diaper. From such a viewpoint, the light transmittance of the back sheet 3 is preferably 30 to 80%, particularly preferably 35 to 80%.
[0029]
The light transmittance of the back sheet 3 is measured as follows.
<Measurement method of light transmittance>
The value of the total light transmittance Tt is measured using a measurement light source A light source under the trade name “HR-100” manufactured by Murakami Color Research Laboratory. Any 10 points on the back sheet are measured, and the average value is used as the light transmittance value.
[0030]
In addition to having the above light transmittance, the back sheet 3 is preferably liquid-impermeable and moisture-permeable. According to JIS Z0208, the moisture permeability of the back sheet 3 is 0.5 to 4.0 g / (100 cm ² · hr), which is a value of the sample after storage at 32 ° C. for 1 hour, and is suitable for the inside of the diaper. It is preferable from the point that comfortable wear can be obtained by proper humidity adjustment, and that leakage of body fluid is prevented.
[0031]
As a material used for the back sheet 3 having such liquid impermeability and moisture permeability, for example, a porous film may be mentioned. For example, a porous film is formed by melting and kneading a hydrophobic thermoplastic resin and a fine inorganic filler such as calcium carbonate or an organic polymer incompatible with the resin to form a film. Or it is obtained by biaxial stretching. Examples of the thermoplastic resin include polyolefin. Examples of the polyolefin include high- to low-density polyethylene, linear low-density polyethylene, polypropylene, polybutene, and the like, and these can be used alone or as a mixture.
[0032]
It is preferable to use a porous film having a basis weight of 10 to 40 g / m ² as a material of the back sheet 3 because the visual change of the changing agent 10 can be easily recognized from the outside of the diaper and a soft touch can be obtained.
[0033]
The exterior cover sheet 7 preferably has a predetermined light transmittance so that a visual change of the change agent 10 can be easily recognized. The light transmittance of the exterior cover sheet 7 is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. The method for measuring the light transmittance is as described above.
[0034]
It is preferable to use a nonwoven fabric having a basis weight and / or a thickness that allows the light transmittance to be obtained, so that the changing agent 10 can be seen through the outside of the diaper. When the nonwoven fabric has a basis weight of 5 to 45 g / m ² , particularly 10 to 40 g / m ² , both the recognizability of the visual change of the changing agent 10 and the sensual performance such as texture and feel are compatible. Preferred from the point.
[0035]
As the nonwoven fabric used for the exterior cover sheet 7, for example, fibers of a thermoplastic resin alone made of a polyolefin such as polyethylene or polypropylene, or polyester such as polyethylene terephthalate, or a core-sheath type or side-by-side made of two or more of these resins Non-woven fabrics composed of conjugate fibers having a mold structure are exemplified.
[0036]
As the nonwoven fabric used for the exterior cover sheet 7, it is preferable to use a nonwoven fabric having a high ground color transparency and a high whiteness because the visual change of the change agent 10 is enhanced. However, the exterior cover sheet 7 may be configured such that, in the diaper thickness direction, in the overlapping portion with the region where the changing agent 10 is arranged, most of the overlapping portion is white, and in the region other than the overlapping portion, the changing agent 10 Printing may be performed within a range that does not hinder the recognizability of the visual change.
[0037]
In the present embodiment, three changing agents 10 are arranged side by side in the diaper width direction in a narrow band shape, but the present invention is not limited to this, and the number of changing agents may be one or four or more. . In addition, it is also possible to provide a pattern that does not visually change even when it comes into contact with moisture on the back sheet 3 or the outer cover sheet 7 so as not to overlap the changing agent 10. In the case where such a pattern is provided, for example, when the changing agent 10 changes color before and after contact with moisture, a pattern having substantially the same color as the color of the changing agent 10 before or after the change. Is preferable because it is easier to recognize a change in color.
[0038]
The absorbent article of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the fastening tapes 8 and 8 are provided on the left and right side edges of the back side portion A. Instead, a pair of waist bands extending laterally are provided on the left and right side edges of the back side portion A. May be provided. Then, a band fastening portion may be provided at the tip of one of the waistbands, and the left and right waistbands may be fastened to the wearer's abdomen or back by the fastening portion.
[0039]
Further, the above embodiment relates to the unfolded disposable diaper, but the present invention is similarly applicable to other absorbent articles, for example, pants-type disposable diapers, sanitary napkins, sanitary shorts, and the like. .
[0040]
【The invention's effect】
INDUSTRIAL APPLICABILITY The absorbent article of the present invention is such that a visual change indicating the replacement time due to urination can be easily recognized from outside the diaper.
[Brief description of the drawings]
FIG. 1 is a partially cutaway plan view of a disposable diaper as one embodiment of the present invention as viewed from a back sheet side.
FIG. 2 is a sectional view taken along line II-II in FIG.
[Explanation of symbols]
1 disposable diapers (absorbent articles)
2 Top sheet 3 Back sheet 4 Absorber 41 Absorbent core 42 Shape-retaining sheet 43 Thin paper 5 Waist section 6 Leg section 7 Exterior cover sheet 8 Fastening tape 9 Landing tape 10 Hydrophilic composition (change agent)

Claims (5)

An absorbent article comprising an absorber and a liquid-impermeable back sheet on the side opposite to the wearer's skin contact surface side of the absorber,
The absorber comprises an absorbent core containing a superabsorbent polymer and a shape-retaining sheet covering the periphery thereof,
Thin paper is interposed between the shape-retaining sheet and the back sheet,
An absorbent article comprising a hydrophilic composition that visually changes when it comes into contact with moisture in a predetermined portion between the thin paper and the back sheet. The absorbent article of claim 1 wherein the basis weight of the web material is 5 to 30 g / ^{m 2.} The absorbent article according to claim 1, wherein the shape retaining sheet is made of a hydrophilic nonwoven fabric. The absorbent article according to any one of claims 1 to 3, wherein the thin paper exists only on the back sheet side of the absorbent article. The absorbent article is substantially vertically elongated and includes a crotch portion and a ventral portion and a dorsal portion extending back and forth from the crotch portion, wherein the hydrophilic composition extends from the abdominal portion to the dorsal portion. The absorbent article according to any one of claims 1 to 4, wherein the absorbent article is present along a longitudinal direction.

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