JP2003210522A - Absorbing article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbing article which does not change color when it comes in contact with a small amount of water, and also does not change color in the case that it is kept under high temperature and high humidity in the absorbing article capable of indicating whether an excrement such as a urine or the like is absorbed or not by the change in color. <P>SOLUTION: The absorbing article 1 contains an acidic compound and a hydrophilic composition containing a color indicator which changes color by a change in pH. This hydrophilic composition exists between a back sheet 3 and an absorbent 4. The back sheet 3 is made of a sheet material containing a water-soluble compound which exhibits alkaline property when dissolved in water. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to absorbent articles such as disposable diapers and sanitary napkins, and more specifically,
The present invention relates to an absorbent article capable of indicating whether or not excrement such as urine has been absorbed by changing a color.

[0002]

2. Description of the Related Art A substance (indicator) that changes color due to a change in pH is incorporated into a disposable diaper to indicate whether or not excrement such as urine has been absorbed. Techniques related to signatures are known (see, for example, Patent Documents 1 to 4). The techniques described in these patent documents utilize the fact that the pH of a substance mixed with an indicator changes from acidic to neutral or alkaline due to water, and the color of the indicator changes accordingly.

However, according to the techniques described in these patent documents, 1) the indicator is discolored only by contact with a small amount of water, and a notice sign appears even though the diaper is still usable. Problems and 2) When the diaper is stored under high temperature and high humidity, there is a problem that the indicator discolors due to the moisture in the air, and the notification sign function is lost before using the diaper.

[0004]

[Patent Document 1] Japanese Utility Model Laid-Open No. 63-177907

[Patent Document 2] Japanese Patent Publication No. 2-5792

[Patent Document 3] JP-A-2-58585

[Patent Document 4] Japanese Unexamined Patent Publication No. 2-97584

Therefore, an object of the present invention is to provide an absorbent article capable of indicating whether or not excrement such as urine has been absorbed by changing its color, and discoloration does not occur even if it is contacted with a small amount of water. Another object of the present invention is to provide an absorbent article that does not discolor even when stored under high temperature and high humidity.

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors, a combination of a specific hydrophilic composition containing a specific component and a sheet material containing a specific compound was used. It was found that an absorbent article that can achieve the above object can be obtained.

The present invention has been made on the basis of the above findings, and in an absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet and a liquid-retaining absorber interposed between both sheets, The absorbent article contains a hydrophilic composition containing a color change indicator that changes color due to a change in pH with an acidic compound, and the back sheet,
By providing a sheet material containing a water-soluble compound exhibiting alkalinity when dissolved in water, the hydrophilic composition is provided between the back sheet and the absorbent body to provide an absorbent article, thereby achieving the above object. It has been achieved.

The present invention also provides a liquid-permeable topsheet,
An absorbent article having a liquid-impermeable back sheet and a liquid-retaining absorber interposed between the both sheets, the back sheet being made of a sheet material containing a water-soluble compound that exhibits alkalinity when dissolved in water. Prior to the step of assembling the absorbent article from the top sheet, the back sheet and the absorber, the method for producing a color change in which the color is changed by the acidic compound and the change in pH directly on the inner surface of the back sheet. It is intended to provide a method for producing an absorbent article, which comprises a step of applying a hydrophilic composition containing an indicator in a stripe shape along the longitudinal direction of the absorbent article.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the absorbent article of the present invention will be described with reference to the drawings, taking a disposable diaper as an example. Here, FIG. 1 shows a disposable diaper as one embodiment of the absorbent article of the present invention,
FIG. 2 is a partially cutaway plan view seen from the back sheet side.
FIG. 2 is an enlarged sectional view taken along the line I-I of FIG. 1.

As shown in FIGS. 1 and 2, the disposable diaper 1 of the present embodiment has a liquid-permeable top sheet 2 and
Liquid-impermeable back sheet 3 and both sheets 2 and 3
And a liquid-retaining absorber 4 interposed therebetween. The absorber 4 is curved and formed in an hourglass shape in which a region corresponding to the crotch region of the diaper is constricted.
The back sheet 3 also has a curved region corresponding to the crotch region of the diaper according to the shape of the absorber 4. The absorber 4 is sandwiched and fixed by the top sheet 2 and the back sheet 3.

Waist portions 5 and 5'on the back side and the abdomen side formed by a top sheet 2 and a back sheet 3 extending outward from the front and rear and left and right edge portions of the absorbent body 4, and a pair of leg portions 6, respectively. An elastic elastic member 7 for fitting the waist portions 5, 5 ′ and the leg portions 6, 6 to the wearer's body when the diaper is worn is included in the topsheet 2
And fixedly provided by the back sheet 3. A pair of fasteners 8 made of tape fasteners and the like are attached to both ends of the back waist portion 5 in the width direction, and a rectangular shape is formed on the back sheet 3 in the abdominal waist portion 5 '. An adherend 9 made of a landing tape or the like is attached. Then, when the disposable diaper 1 of the present embodiment is worn, the fasteners 8 are fastened on the adherend 9. The above configuration is
It is similar to a conventional disposable diaper.

Thus, in the disposable diaper 1 of this embodiment, as shown in FIGS. 1 and 2, the back sheet 3 is used.
Is composed of a sheet material containing a water-soluble compound that exhibits alkalinity when dissolved in water, and the hydrophilic composition 10 is directly applied to the inner surface of the back sheet 3 in four streaks along the longitudinal direction of the diaper. Cage, backsheet 3 and absorber 4
And are joined and fixed. In addition, in this specification, "alkaline" means that pH is more than 7.

The hydrophilic composition 10 contains a hydrophilic composition containing an acidic compound and a color change indicator whose color changes with a change in pH, and the water-soluble compound in the sheet material is brought into contact with water. When the contacted water comes into contact with the hydrophilic composition, the pH of the hydrophilic composition becomes higher than 4 and the color of the hydrophilic composition changes.

As the acidic compound contained in the hydrophilic composition, the pH of the hydrophilic composition can be kept at 4 or less, and the pH of the hydrophilic composition is 4 only when the hydrophilic composition is brought into contact with water. Those that can be maintained so as not to exceed Examples of such acidic compounds include vinyl acetate homopolymers, polymer compounds such as ethylene / vinyl acetate copolymers and ethylene / acrylic acid copolymers, fatty acids such as stearic acid and oleic acid, rosin acid, L-ascorbic acid, nicotine. Examples thereof include acid, L-glutamic acid, lactic acid, succinic acid, etc., but are not limited thereto. These acidic compounds may be used alone or in combination of two or more. Among these acidic compounds, particularly preferable are a combination of vinyl acetate homopolymer and ethylene / acrylic acid copolymer, a combination of ethylene / vinyl acetate copolymer and rosin acid, a combination of vinyl acetate homopolymer and stearic acid, and acetic acid. Examples include a combination of vinyl homopolymer, rosin acid and ethylene / acrylic acid copolymer, a combination of ethylene / vinyl acetate copolymer and lactic acid, a combination of L-ascorbic acid and stearic acid, and the like. These acidic compounds are preferably 50 to 99.99% by weight, and more preferably 60 to 9% by weight based on the total amount of the hydrophilic composition (acidic compound + coloration indicator).
99.99% by weight, more preferably 60 to 99% by weight. If the amount of acidic compound is less than 50% by weight, p
It is difficult to keep H at 4 or less, and discoloration may occur just by contact with water.

As the color change indicator which is the other component contained in the above hydrophilic composition, a color change indicator having a pH of 3 to 7 is used, examples of which include bromophenol blue and methyl orange. Examples thereof include alizarin S, bromocresol green, methyl red, bromocresol purple, etc., but are not limited thereto. Among these color change indicators, bromophenol blue, bromocresol green, bromocresol purple and the like are particularly preferable. These color indicators are preferably 0.01 to 50% by weight, more preferably 0.01 to 40% by weight, and even more preferably 0, relative to the total amount of the hydrophilic composition (acidic compound + color indicator). 0.01-1% by weight, most preferably 0.01-
It is contained at 0.5% by weight. If the amount of the color change indicator is less than 0.01% by weight, the color may be light even if it discolors and may be difficult to be visually recognized from the outside. If it exceeds 50% by weight, the color of the hydrophilic composition before discoloration is dark. It is preferable that the amount is in the above range because the appearance may not be good and the cost may be further increased.

The above-mentioned hydrophilic composition sufficiently exhibits the effects of the present invention even if it comprises only the above-mentioned acidic compound and the above-mentioned color change indicator, but in addition to these components, a hydrophilic polymer having an adhesive property is also added. When contained, the hydrophilic composition is provided with hot melt adhesiveness, and the back sheet 3 and the absorber 4 are provided.
In addition to being more robust in joining and fixing with, it is possible to coat on line if there is a hot melt coating device,
Processability is improved. That is, the hydrophilic composition containing the acidic compound, the color change indicator, and the hydrophilic polymer functions as a hot melt adhesive. The hydrophilic polymer is not particularly limited as long as it has tackiness and hydrophilicity, and examples thereof include vinylpyrrolidone homopolymer, polyamide, and polyvinyl alcohol. Among these hydrophilic polymers, vinylpyrrolidone homopolymer and polyvinyl alcohol are particularly preferable. These hydrophilic polymers have a number average molecular weight of 500 to 30,0 from the viewpoint of imparting appropriate hot melt adhesiveness to the hydrophilic composition.
00 is preferable and 1,000 to 10,000
Is more preferable. These hydrophilic polymers are contained in an amount of 20 to 50% by weight based on the total amount of the hydrophilic composition.
It is preferably contained, and more preferably 30 to 40% by weight. If the amount of the hydrophilic polymer is less than 20% by weight, water may be difficult to be taken into the hydrophilic composition and discoloration may be less likely, and if it exceeds 50% by weight, the amount of the acidic compound compounded is relatively high. Decrease pH
It is difficult to keep the value of 4 or less, and the color may change only by contacting with water. Therefore, it is preferably within the above range. That is, when the hydrophilic composition contains the acidic compound, the color change indicator, and the hydrophilic polymer, a preferable combination is 25 to 79.99% by weight of the acidic compound and 0.01 to 25% by weight of the color change indicator. , Hydrophilic polymer 20 ~
It is 50% by weight, and more preferable composition is acidic compound 3.
0 to 69.99% by weight, color indicator 0.01 to 30% by weight, and hydrophilic polymer 30 to 40% by weight.

Further, the hydrophilic composition may contain an antioxidant, an ultraviolet absorber and the like in addition to the above-mentioned components. It is preferable that these components are contained in an amount of 0.5 to 5% by weight based on the total amount of the hydrophilic composition.
It is more preferable that the content is 3 wt%.

The above hydrophilic composition can be prepared by stirring and mixing the above-mentioned components at, for example, about 150 ° C. for about 60 minutes.

Next, the sheet material used as the back sheet 3 will be described. As described above, the sheet material contains a water-soluble compound that exhibits alkalinity when dissolved in water, and when the sheet material comes into contact with water. The water-soluble compound is eluted so that the contacted water exhibits alkalinity. The water-soluble compound is not particularly limited as long as it is soluble in water (but need not be completely soluble) and exhibits alkalinity when dissolved in water, and examples thereof include inorganic or organic fillers (fillers). ) Can be used. Examples of such fillers include inorganic ones such as calcium carbonate, magnesium carbonate, barium carbonate and sodium carbonate, and organic ones such as sodium oleate, sodium acetate, barium acetate, calcium stearate and stearic acid. Magnesium or the like can be used. Of these fillers, calcium carbonate and calcium stearate are particularly preferably used.

The sheet material is preferably formed of a resin composition containing the water-soluble compound and a thermoplastic resin, and particularly contains the filler as the water-soluble compound and a polyolefin resin as the thermoplastic resin. It is preferably formed from a resin composition. The sheet material may be a moisture-permeable sheet or a non-moisture-permeable sheet, but is preferably a moisture-permeable sheet from the viewpoint of effectively preventing stuffiness inside the diaper and accompanying skin rash on the wearer's skin.

When the sheet material is a moisture permeable sheet,
The average particle diameter of the filler (water-soluble compound) is preferably 30 μm or less, from the viewpoint of forming a large number of fine pores in the sheet material and giving sufficient moisture permeability, and 10 μm.
The following is more preferable, and 0.5 μm to 5 μm is most preferable. The filler (water-soluble compound) is preferably surface-treated from the viewpoint of uniform dispersibility in the polyolefin resin. For the surface treatment, a fatty acid or a metal salt thereof that can make the surface hydrophobic is preferably used. Incidentally, the moisture-permeable sheet is a method known in the art, for example, a film or sheet obtained by kneading the above-mentioned polyolefin resin with the above-mentioned filler (water-soluble compound) and melt-molding the same, or biaxially. It is obtained by stretching.

When the above-mentioned sheet material is a moisture permeable sheet, its moisture permeability is such that the amount of moisture permeation is sufficient to prevent stuffiness inside the diaper and the accompanying skin rash of the wearer while maintaining liquid impermeability. From 0.5 to 4 g / (100 cm ² · h)
Is preferable, and more preferably 1.0 to 2.5.
It is g / (100 cm ² · h). The moisture permeability is
It is a value measured according to JIS Z 0208.

As the above-mentioned polyolefin resin, for example, a resin containing a monoolefin polymer or copolymer such as ethylene, propylene or butene as a main component is used.
For example, examples of the polyolefin resin include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, crystalline ethylene-propylene block copolymer, polybutene, ethylene-vinyl acetate copolymer, and mixtures thereof. Among them, linear low-density polyethylene is desirable because it is flexible and tough.

The resin composition for forming the sheet material may contain 50 to 400 parts by weight, especially 50 to 250 parts by weight of the filler (water-soluble compound) per 100 parts by weight of the polyolefin resin. It is preferable from the viewpoint of securing a wet amount and the ability of the contacted water to be changed to alkaline.

In the above resin composition, an ester compound is added to the polyolefin resin 10 for the purpose of improving the sheet strength of the sheet material and forming continuous fine pores in the sheet material even at a low draw ratio.
The amount can be preferably 5 to 50 parts by weight with respect to 0 parts by weight. Examples of the ester compound include esters of stearic acid, adipic acid and trimethylolpropane, castor oil, hydrogenated castor oil, ethylene oxide adduct of hydrogenated castor oil, polyesters of glycols and dimer acid, and the like.

The thickness of the above-mentioned sheet material is 15 to 40 μ from the viewpoints of sheet strength, texture, thickness control during production and the like.
m is preferable, and more preferably 20 to 35 μm.
m.

The basis weight of the above-mentioned sheet material is not particularly limited, but it is preferably 15 to 40 g / m ² from the viewpoint of difficulty in controlling the thickness at the time of production, and the feel and touch, and preferably ²⁰ to 35 g / m ^2. It is more preferably m ² .

Next, the mechanism of discoloration of the hydrophilic composition in the disposable diaper of this embodiment will be described. When excrement such as urine excreted from the wearer is absorbed by the absorbent body 4, when the amount thereof is small, the excrement is in contact with the hydrophilic composition, or the hydrophilic composition. To the back sheet 3 and a small amount of the back sheet 3. By the way, in the hydrophilic composition, as described above, the pH of the hydrophilic composition can be maintained at 4 or less, and the pH does not exceed 4 only when the hydrophilic composition comes into contact with water. Since it contains an acidic substance that can be maintained as described above, when the excrement such as urine having a pH of the same level as or lower than that of water comes into contact with the hydrophilic composition, the hydrophilic composition No discoloration of objects occurs. In addition, even if a small amount of excrement such as urine comes into contact with the backsheet 3, the excrement does not elute the water-soluble compound in the backsheet 3 (sheet material), so that the pH of the excrement hardly changes, Again, no color change of the hydrophilic composition occurs. In this way, when the amount of excretions such as urine excreted from the wearer is small,
Since the discoloration of the hydrophilic composition does not occur, unlike a conventional disposable diaper, it is possible to prevent the diaper that is still usable from being replaced on the way. Similarly, even when the diaper is stored under high temperature and high humidity, due to the same reason as above, discoloration of the hydrophilic substance does not occur due to the small amount of water present in the air, and therefore, during storage, Discoloration is prevented from occurring. On the other hand, when a certain amount of urine or the like is absorbed and accumulated in the absorbent body 4, the urine or the like comes into contact with the backsheet 3 to elute the water-soluble compound in the backsheet 3 (sheet material) to The pH is made alkaline (this pH is about 7-9). Then, when alkaline urine or the like in which the water-soluble compound is dissolved comes into contact with the hydrophilic composition, the pH of the hydrophilic composition becomes higher than 4 (that is, from acidic to neutral or alkaline). ), The color of the hydrophilic composition changes. Since this color change can be visually recognized from the outside through the back sheet 3, it is possible to know the proper replacement time of the diaper by the color change.

Although the absorbent article of the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. Is. For example, in the above-described embodiment, the hydrophilic composition 10 is directly applied onto the sheet material as the backsheet 3, but instead of this, as shown in FIG. 3, the sheet material and the hydrophilic substance are combined. A hydrophilic sheet 11 such as a tissue paper or a hydrophilic non-woven fabric may be interposed therebetween to further enhance the storage stability in the presence of a small amount of water or in a high humidity environment. In addition, in FIGS. 2 and 3, the hydrophilic composition 10 is applied in a plurality of strips along the longitudinal direction of the diaper, but instead of this, on the sheet material or on the hydrophilic sheet. The hydrophilic composition may be applied over the entire surface. In addition to the disposable diaper, the absorbent article of the present invention can be applied as a sanitary napkin, an incontinence pad, a breast milk pad, or the like.

[0030]

EXAMPLES The effectiveness of the absorbent article of the present invention will be illustrated by the following examples. However, the scope of the present invention is not limited to such embodiments. In the following examples, "%" means "% by weight" unless otherwise specified.

Example 1 Vinylpyrrolidone homopolymer (hydrophilic polymer) 33.8%, ethylene / vinyl acetate copolymer (acidic compound) 35%, rosin acid (acidic compound) 30%, bromophenol blue (coloring indicator) )
150% by mixing 0.2% and 1% of Irganox 1010 [antioxidant (trade name) manufactured by Ciba-Geigy)
And stirred to prepare a hydrophilic composition. This hydrophilic composition was coated by a slot coater method in the form of a film on a back sheet composed of a moisture-permeable sheet manufactured by the following method (coating amount: 20 g / m ² , coating temperature: 120 ° C., coating temperature: 120 ° C.). Speed 2
0 m / min). 100% pulp and 1 basis weight on the coated surface
A 9 g / m ² mount (tissue paper) was attached. An absorbent body made of a mixture of fluff pulp and superabsorbent polymer particles is laminated on a mount, and the top sheet made of a suction heat bond nonwoven fabric of polypropylene fiber is coated on the absorbent body, and the peripheral portion of the back sheet and the top sheet is covered. A disposable diaper shown in FIG. 3 was manufactured by joining and fixing these with an elastic elastic member interposed therebetween.

<Production Method of Moisture Permeation Sheet> 100 parts by weight of linear low-density polyethylene [Ultzex 2520F (trade name) manufactured by Mitsui Petrochemical Industry Co., Ltd.] and surface-treated calcium carbonate (average particle size: 1 μm) To 150 parts by weight, 10 parts by weight of the ester compound having the composition and physical property values shown in Table 1 were added and kneaded with a twin-screw type kneader to prepare pellets. The obtained pellets were supplied to an inflation molding machine to mold an inflation sheet having a thickness of 80 μm. The obtained sheet was stretched at a stretching temperature of 50 ° C. with a stretching ratio of 2.3 using a roll stretching machine to obtain a porous moisture permeable sheet. The thickness of this sheet is 40 μm, and the moisture vapor transmission rate (JIS Z 0208) is 1.8 g / (100 c
m ² · h) and the basis weight was 20 g / m ² .

[0033]

[Table 1]

[Performance Evaluation] With respect to the disposable diaper obtained as described above, the degree of discoloration of the hydrophilic composition when absorbed with physiological saline and stored under high temperature and high humidity was measured by the following method. evaluated. The results are shown in Table 3.

<Discoloration of Hydrophilic Composition When Absorbing Physiological Saline> 5 g and 40 g of physiological saline are injected from the top sheet side of the obtained disposable diaper, and then left for 2 minutes. After leaving, it is visually confirmed whether or not the hydrophilic substance is discolored. The degree of discoloration is evaluated according to the following criteria. ○ ... Discolored within 2 minutes. B: Discolored before 10 minutes after exceeding 2 minutes. × ... No discoloration after 10 minutes.

<Discoloration of hydrophilic composition when stored under high temperature and high humidity> The obtained disposable diaper is
Leave at 90% RH for 24 hours, then at room temperature (23 ° C ・ 6
The degree of discoloration of the hydrophilic substance when returned to 5% RH) is evaluated according to the following criteria. ○ ・ ・ No discoloration. △ ... Slightly discolored. × ... Almost discolored.

[Examples 2 to 4] Using the components shown in Table 2, a hydrophilic composition was prepared in the same manner as in Example 1. After that, a disposable diaper was manufactured in the same manner as in Example 1, and the obtained disposable diaper was evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0038]

[Table 2]

[Example 5] A disposable diaper was produced in the same manner as in Example 1 except that the backsheet used in Example 1 was replaced with calcium stearate as the backsheet. The disposable diaper was evaluated in the same manner as in Example 1. The results are shown in Table 3.

[Comparative Examples 1 to 4] Disposable diapers were produced in the same manner as in Examples 1 to 4 except that a sheet made of linear low-density polyethylene was used as the back sheet. The same evaluation as in Example 1 was performed. The results are shown in Table 3. The backsheet used in this comparative example contains no water-soluble compound.

[0041]

[Table 3]

As is clear from the results shown in Table 3, the disposable diapers of Examples 1 to 5 containing the hydrophilic composition containing the specific components and using the specific sheet material as the back sheet (the present invention) It can be seen that, as compared with the disposable diapers of Comparative Examples 1 to 4 in which the water-soluble compound is not contained in the back sheet, the product) discolors when it absorbs an appropriate amount of physiological saline.

[0043]

As described above in detail, according to the absorbent article of the present invention, discoloration does not occur even when contacted with a small amount of water, and discoloration occurs even when stored under high temperature and high humidity. Since it does not occur, it can be prevented from being replaced or discolored during storage even though it is still usable.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of a disposable diaper as one embodiment of an absorbent article of the present invention, viewed from the back sheet side.

FIG. 2 is an enlarged cross-sectional view taken along the line II of FIG.

FIG. 3 is a view showing another embodiment of the absorbent article of the present invention.
FIG.

[Explanation of symbols]

1 disposable diapers 2 top sheet 3 back sheet 4 absorber 10 Hydrophilic composition 11 Hydrophilic sheet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A61F 13/53 (72) Inventor Tadashi Wada 2606 Akabane, Kaicho, Haga-gun, Tochigi Prefecture Kao Corporation Stock Research Institute ) Inventor Masao Kurahashi 2606 Akabane, Kaigamachi, Haga-gun, Tochigi Prefecture F-term inside Kao Institute of Stock Company (reference) 3B029 BA18 BC03 BC06 BE03 4C003 CA04 DA01 4C098 AA09 CC03 CC08 CC10 CC15 CD09 DD01 DD02 DD03 DD14 DD25 DD27

Claims (5)

[Claims] 1. An absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between the both sheets, wherein the absorbent article comprises an acidic compound and a pH. Contains a hydrophilic composition containing a color change indicator whose color changes according to changes in the backsheet, wherein the backsheet is composed of a sheet material containing a water-soluble compound that exhibits alkalinity when dissolved in water, and the hydrophilic composition Is present between the back sheet and the absorber. 2. The absorbent article according to claim 1, wherein the sheet material used as the back sheet is a moisture permeable sheet. 3. The absorbent article according to claim 2, wherein the water-soluble compound comprises an inorganic or organic filler, and the filler has an average particle diameter of 30 μm or less. 4. The absorbent article according to claim 1, wherein the hydrophilic substance further contains an adhesive hydrophilic polymer. 5. A water-soluble material having a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between both sheets, the back sheet exhibiting alkalinity when dissolved in water. A method for producing an absorbent article comprising a sheet material containing a hydrophilic compound, wherein the top sheet, the back sheet and the step of assembling the absorbent article from the absorbent body, directly on the inner surface of the back sheet, acidic. A hydrophilic composition containing a compound and a color change indicator whose color changes according to a change in pH,
A method for manufacturing an absorbent article, comprising a step of applying the absorbent article in a streak shape along a longitudinal direction.