Indicator for absorbent article and absorbent article including same

Abstract

To provide an indicator for an absorbent article which hardly dissolves in a water component such as urine and moisture and can detect a change in urine specific gravity with accuracy, and the absorbent article including the same.SOLUTION: An indicator for an absorbent article in the invention is adjusted to an appearance color of an alkali side in an initial state before making contact with urine, can change into a color corresponding to the urine specific gravity in making contact with the urine, and includes a pH indicator, an aliphatic alcohol of at least 20 mass% in a solid state at a normal temperature, and at least one component of a hydrophilic polymer of at least 10 mass% and an amine-based cationic surfactant of at least 10 mass%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an indicator for use in an absorbent article such as a disposable diaper, and to an absorbent article including the indicator. [Background technology]

[0002] 2. Description of the Related Art Among absorbent articles such as disposable diapers, there are known absorbent articles that are provided with an indicator capable of detecting the presence or absence of urination or a change in the wearer's health condition by a change in color.

[0003] Furthermore, in recent years, indicators for measuring urine specific gravity by colorimetry have been put to practical use, and such indicators are composed of an aqueous solution containing components such as a pH indicator and a surfactant that can change color depending on urine specific gravity, and are used after being impregnated into a substrate such as a film and dried. For example, Patent Document 1 discloses an indicator that improves responsiveness to salt concentration by mixing a surfactant into a pH indicator, and converts changes in urine specific gravity into changes in the color of the pH indicator.

[0004] Although not related to the change in urine specific gravity, indicators for urine detection made of thermoplastic solid substances using a similar principle have also been put to practical use. For example, Patent Document 2 discloses a thermoplastic indicator composition adjusted to an alkaline state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-196616 [Patent Document 2] Special Publication No. 2015-529151 Summary of the Invention [Problem to be solved by the invention]

[0006] Water-soluble indicators such as those in Patent Document 1 dissolve in a short time when they come into contact with urine, so they can only detect the urine specific gravity at the beginning of urination, and there is a risk that they cannot accurately detect changes in urine specific gravity. Furthermore, such water-soluble indicators are vulnerable to moisture, so they react to moisture during storage before use and discolor, and there is a risk that they cannot accurately detect changes in urine specific gravity when used.

[0007] Even if an attempt is made to address these problems by incorporating a thermoplastic indicator composition as described in Patent Document 2, such a composition contains components that are formulated with a primary focus on the stability of the reaction when in contact with urine, and therefore has low reactivity with respect to detecting urine specific gravity, so there is still a risk that changes in urine specific gravity cannot be detected accurately.

[0008] Therefore, an object of the present invention is to provide an indicator for absorbent articles that is difficult to dissolve in moisture such as urine or humidity and can accurately detect changes in urine specific gravity, and an absorbent article including the indicator. [Means for solving the problem]

[0009] One aspect of the present invention (Aspect 1) is an indicator for an absorbent article, The indicator is adjusted to have an appearance color on the alkaline side in an initial state before contacting with urine, and is capable of changing color to a color corresponding to the specific gravity of urine upon contact with urine, A pH indicator, 20% by mass or more of an aliphatic alcohol that is solid at room temperature; At least one of 10% by mass or more of a hydrophilic polymer and 10% by mass or more of an amine-based cationic surfactant; The indicator comprises:

[0010] The indicator of the present embodiment 1 does not undergo a color change for detecting the presence or absence of urination (i.e., a color change from the acidic side of the pH indicator in the indicator to the alkaline side), but rather detects the presence or absence of urination according to the urine specific gravity (i.e., the concentration of sodium ions (Na + ) and potassium ions (K+ ), calcium ion (Ca 2+ ), magnesium ion (Mg 2+ Since the color of the appearance changes from the alkaline side depending on the ion concentration of the aqueous solution, when the aqueous solution is applied to an absorbent article such as a disposable diaper, the wearer of the absorbent article or his / her assistant can easily recognize the change in urine specific gravity.

[0011] The indicator of this embodiment 1 contains a predetermined amount of aliphatic alcohol that is solid at room temperature (20°C), and is therefore less likely to dissolve in moisture such as urine or humidity. In addition, the indicator contains a predetermined amount of at least one of a hydrophilic polymer and an amine-based cationic surfactant, and therefore is highly responsive in changing color to changes in urine specific gravity when in contact with urine, and can clearly change color even when the change in urine specific gravity is small.

[0012] As described above, the indicator of the present embodiment 1 is not easily dissolved in water such as urine or moisture, and can accurately detect changes in urine specific gravity.

[0013] In another aspect (aspect 2) of the present invention, in the indicator of aspect 1, the aliphatic alcohol has a melting point higher than 40°C and lower than 110°C.

[0014] In the indicator of the present embodiment 2, since the aliphatic alcohol has the above-mentioned specific melting point, when it is applied in a molten state to a substrate such as a nonwoven fabric or a film, it cools and solidifies, and the indicator can be formed uniformly at an appropriate position on the substrate. As a result, the indicator of the present embodiment 2 can detect sodium ions (Na + ) and potassium ions (K + ), calcium ion (Ca 2+ ), magnesium ion (Mg 2+ ) and even if the color change is small, it is easy to see, allowing for more accurate and reliable detection of changes in urine specific gravity.

[0015] In still another aspect (aspect 3) of the present invention, in the indicator of aspect 1 or 2, the hydrophilic polymer contains polyamide.

[0016] In the indicator of the present embodiment 3, the hydrophilic polymer contains polyamide, which acts on the morphological change of the pH indicator, widens the range of color change in response to urine specific gravity, has a strong dissolving effect, and has a fast response speed, so that the indicator of the present embodiment 3 can accurately detect a wide range of changes in urine specific gravity.

[0017] In still another aspect (Aspect 4) of the present invention, in the indicator of any one of Aspects 1 to 3 above, the amine-based cationic surfactant contains a quaternary ammonium salt.

[0018] In the indicator of the present embodiment 4, the amine cationic surfactant contains a quaternary ammonium salt, so that the indicator has high surface activity and changes color more quickly when it comes into contact with urine, which allows the indicator of the present embodiment 4 to detect changes in urine specific gravity with higher accuracy.

[0019] In still another aspect (aspect 5) of the present invention, in the indicator of any one of aspects 1 to 4 above, the pH indicator comprises two or more types of pH indicators.

[0020] The indicator of the fifth embodiment can detect the change in urine specific gravity more accurately and reliably by combining two or more pH indicators, which can clearly change color even for urine with a smaller difference in specific gravity. Also, by combining two or more pH indicators with different color change ranges, the detection range of urine specific gravity can be expanded, and the degree of color change due to the change in urine specific gravity can be increased, making it easier to see.

[0021] In yet another aspect (Aspect 6) of the present invention, the indicator of any one of Aspects 1 to 5 above is characterized in that it further comprises, as the sugar alcohol component, at least one component selected from the group consisting of a sugar alcohol and a sugar alcohol polymer, in a blending ratio of 2.5 mass% or more.

[0022] The indicator of the sixth embodiment contains the sugar alcohol component, and therefore has increased hydrophilicity, which can increase the rate of color change when it comes into contact with urine.

[0023] In still another aspect (aspect 7) of the present invention, the indicator of any one of aspects 1 to 6 above is characterized in that it further contains at least one component selected from the group consisting of wax, oil, and tackifier resin as a hydrophobic component.

[0024] Since the indicator of the seventh aspect contains the above-mentioned specific hydrophobic component, it has high fixability to a substrate such as a nonwoven fabric or a film, and the indicator can be accurately formed at a predetermined position on the substrate. As a result, the indicator of the seventh aspect can detect the change in urine specific gravity more accurately and reliably.

[0025] In still another aspect (Aspect 8) of the present invention, the indicator according to any one of Aspects 1 to 7 above is characterized in that it further contains sodium carbonate as an alkalizing agent.

[0026] The indicator of the present embodiment 8 contains sodium carbonate (Na2CO3) as an alkalizing agent, which can be mixed more uniformly with other components in the indicator than other alkalizing agents such as sodium hydroxide (NaOH) or potassium carbonate (K2CO3), making it less likely to cause uneven or abnormal discoloration, and making the discoloration easier to visually recognize even when the color change is small. This allows the indicator of the present embodiment 8 to detect changes in urine specific gravity more accurately and reliably.

[0027] In yet another aspect (Aspect 9) of the present invention, in an indicator according to any one of Aspects 1 to 8 above, the indicator changes color to blue or green when it comes into contact with low specific gravity urine, and changes color to yellow or orange when it comes into contact with high specific gravity urine.

[0028] The indicator of this aspect 9 is different from the color change for detecting the presence or absence of urination (i.e., the color change from the acidic side color of the pH indicator in the indicator to the alkaline side color), in that it changes color to blue or green when it comes into contact with low specific gravity urine and changes color to yellow or orange when it comes into contact with high specific gravity urine, so that when it is applied to an absorbent article such as a disposable diaper, it is easy for the wearer of the absorbent article or his / her assistant to recognize the change in urine specific gravity, and in particular, the color change from the initial state before contact with urine to yellow or orange when it comes into contact with high specific gravity urine is more easily visible. As a result, the indicator of this aspect 9 can detect the change in urine specific gravity more accurately and more easily.

[0029] Yet another aspect (aspect 10) of the present invention is an absorbent article comprising the indicator of any one of aspects 1 to 9 above.

[0030] The absorbent article of this aspect 10 includes the indicator of any one of the above aspects 1 to 7, and can accurately detect a change in the specific gravity of the wearer's urine, allowing the wearer of the absorbent article or an assistant to accurately recognize the change in the specific gravity of the wearer's urine. As a result, the absorbent article of this aspect 10 can more accurately grasp the timing of toilet training of the wearer, signs of dehydration, etc., of the wearer, such as an infant. Effect of the Invention

[0031] The indicator of the present invention is not easily dissolved in water such as urine or moisture, and can accurately detect changes in urine specific gravity. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a perspective view of a disposable diaper 1 to which an indicator 5 according to one embodiment of the present invention is applied. [Diagram 2] FIG. 2 is an enlarged end view of a cross section taken along line II-II of the disposable diaper 1 in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The indicator of the present invention will be described in detail below using an embodiment in which it is applied to a disposable diaper, which is an example of an absorbent article. In this specification, unless otherwise specified, in the thickness direction of the absorbent article, the "side that is relatively closer to the skin surface of the wearer when the absorbent article is worn" is referred to as the "skin-facing side", and the "side that is relatively more distal to the skin surface of the wearer when the absorbent article is worn" is referred to as the "non-skin-facing side".

[0034] [Disposable diapers] FIG. 1 is a perspective view of a disposable diaper 1 to which an indicator 5 according to one embodiment of the present invention is applied, and FIG. 2 is an enlarged end view of a cross section taken along line II-II of the disposable diaper 1 in FIG.

[0035] As shown in Fig. 1, the disposable diaper 1 has a front part that is located on the wearer's lower abdomen when worn, a rear part that is located on the wearer's buttocks when worn, and an intermediate part that is located between the front part and the rear part and that is located on the wearer's crotch when worn. The disposable diaper 1 has a pants-type outer shape with a waist opening formed by the upper end of the front part and the upper end of the rear part, and a pair of leg openings formed on both sides in the left and right direction of the intermediate part, by joining both left and right ends of the front part and the rear part to each other. In other words, the disposable diaper 1 is a so-called pants-type disposable diaper.

[0036] 2, like conventional disposable diapers, the disposable diaper 1 basically comprises a liquid-permeable top sheet 2 located on the skin-facing side in the thickness direction, a liquid-impermeable back sheet 3 located on the non-skin-facing side, a liquid-absorbent absorber 4 provided between these two sheets, and a liquid-responsive indicator 5 provided between the absorber 4 and the back sheet 3. The absorbent core 4 is composed of an absorbent core 4A made of a water-absorbent material such as pulp or superabsorbent polymer (SAP), and a core wrap sheet 4B covering the entire absorbent core 4A and made of a hydrophilic sheet such as tissue.

[0037] In this embodiment, the indicator 5 is formed by melting an indicator composition containing each component described later, applying it to the surface of the skin-facing side of the sheet-like substrate forming the back sheet 3, and then cooling and solidifying it. In the present invention, the means for forming the indicator is not limited to the above, and for example, the indicator composition may be melted and molded into a sheet, and then the sheet-like molded product may be disposed between the absorbent body and the back sheet, or the indicator composition may be melted and applied to the surface of a sheet-like substrate (e.g., a substrate other than the substrate forming the back sheet), and then cooled and solidified to form a laminate, which may be disposed between the absorbent body and the back sheet.

[0038] In the present invention, the position at which the indicator is placed is not particularly limited as long as it is a position that can come into contact with the wearer's urine and is visible from the outer surface of the absorbent article, and as with conventional absorbent articles, it can be placed at any position depending on the desired visibility, etc.

[0039] In the above embodiment, the indicator 5 is disposed at approximately the center in the left-right direction of the disposable diaper 1 and extends in a direction along the front, middle and rear parts. In the present invention, the position of the indicator is not particularly limited, but it is preferable that the indicator is disposed in a wide range from the middle part corresponding to the crotch part of the wearer to the rear part corresponding to the buttocks of the wearer.

[0040] The left-right direction of the disposable diaper 1 corresponds to the width direction of the disposable diaper 1 in the unfolded state, and the direction along the front, middle and rear portions corresponds to the longitudinal direction of the disposable diaper 1 in the unfolded state.

[0041] The indicator 5 used in the disposable diaper 1 of the above-mentioned embodiment is a unique indicator that is adjusted to an alkaline appearance color in the initial state before contact with urine, and can change color to a color corresponding to the specific gravity of urine upon contact with urine, and includes a pH indicator, 20% or more by mass of an aliphatic alcohol that is solid at room temperature, and at least one of 10% or more by mass of a hydrophilic polymer and 10% or more by mass of an amine-based cationic surfactant.

[0042] The indicator 5 of the present embodiment is different from the color change for detecting the presence or absence of urination (i.e., the color change from the acidic side of the pH indicator in the indicator to the alkaline side), and is a color change according to the urine specific gravity (i.e., the Na content in the urine). + Or K + , Ca 2+ , Mg 2+ Since the external color of the disposable diaper 1 changes from the alkaline side (depending on the ion concentration, etc.), it is easy for the wearer of the disposable diaper 1 or his / her assistant to recognize the change in urine specific gravity.

[0043] Furthermore, since the indicator 5 contains a predetermined amount of aliphatic alcohol that is solid at room temperature (i.e., a temperature of 20°C), it is less likely to dissolve in moisture such as urine or humidity. Also, since the indicator 5 contains a predetermined amount of at least one of a hydrophilic polymer and an amine-based cationic surfactant, it is highly responsive in changing color to changes in urine specific gravity when it comes into contact with urine, and can clearly change color even when the change in urine specific gravity is small.

[0044] As described above, the indicator 5 is not easily dissolved in water such as urine or moisture, and can accurately detect a change in urine specific gravity.

[0045] The disposable diaper 1 including such a unique indicator 5 can accurately detect changes in the specific gravity of the wearer's urine, allowing the wearer of the disposable diaper 1 or his / her assistant (for example, the mother of an infant or a caregiver caring for the wearer) to accurately recognize changes in the specific gravity of the wearer's urine. As a result, the disposable diaper 1 including the indicator 5 can more accurately grasp the timing of toilet training of the wearer, signs of dehydration, etc.

[0046] In the absorbent article including the indicator of the present invention, the components other than the indicator are not particularly limited, and any components can be used depending on the type and application of the absorbent article.

[0047] For example, in the above-mentioned disposable diaper 1, the topsheet 2 is disposed at a position on the skin-facing side in the thickness direction of the disposable diaper 1 to form a contact surface that can come into contact with the wearer's skin, i.e., the surface on the skin-facing side of the disposable diaper 1, and is formed of a liquid-permeable sheet-like material such as a nonwoven fabric. The outer shape, various dimensions, basis weight, etc. of the topsheet are not particularly limited as long as they can be used as a topsheet of an absorbent article, and any outer shape, various dimensions, basis weight, etc. can be adopted depending on the desired liquid permeability, texture, flexibility, strength, etc.

[0048] For example, in the above-mentioned disposable diaper 1, the backsheet 3 is disposed at a position on the non-skin facing side in the thickness direction of the disposable diaper 1, forming the surface of the non-skin facing side of the disposable diaper 1, and is formed of a liquid-impermeable sheet-like member such as a resin film or a hydrophobic nonwoven fabric, which is capable of preventing excrement such as urine discharged from the wearer of the disposable diaper 1 from leaking out of the disposable diaper 1. There are no particular limitations on the outer shape, various dimensions, basis weight, etc. of the backsheet, so long as it can be used as a backsheet of an absorbent article, and any outer shape, various dimensions, basis weight, etc. can be adopted according to the desired leak-proof performance, breathability, strength, etc.

[0049] For example, in the above-mentioned disposable diaper 1, the absorbent body 4 is disposed between the top sheet 2 and the back sheet 3, and is formed from an absorbent material with a predetermined liquid absorbency that can absorb and retain excrement such as urine that has permeated through the top sheet 2.

[0050] The absorbent member that can be used in the absorbent is not particularly limited as long as it can absorb and retain excrement such as urine. For example, the above-mentioned disposable diaper 1 is composed of an absorbent core 4A made of an absorbent material containing at least one of absorbent fibers and superabsorbent polymer, and at least one liquid-permeable core wrap sheet 4B (e.g., tissue made of hydrophilic cellulosic fibers) that covers the entire outer surface of the absorbent core. Here, as the absorbent fiber, for example, pulp fiber (e.g., ground pulp), cotton, rayon, acetate, and other cellulosic fibers can be used. As the superabsorbent polymer, for example, starch-based superabsorbent polymers; synthetic polymer-based superabsorbent polymers (so-called "SAP") such as sodium acrylate copolymers, and other granular materials can be used.

[0051] The outer shape, various dimensions, basis weight, etc. of the absorbent body are not particularly limited as long as they can be used as an absorbent body for an absorbent article, and any outer shape, various dimensions, basis weight, etc. can be adopted according to the desired water absorbency, flexibility, strength, etc.

[0052] The absorbent article to which the indicator of the present invention is applied is not particularly limited as long as it is an absorbent article that is intended to absorb at least urine, and in addition to the pants-type disposable diaper of the above-mentioned embodiment, the indicator can be applied to various absorbent articles such as tape-type disposable diapers and incontinence pads.

[0053] For example, when the indicator of the present invention is applied to a disposable diaper for toilet training of infants, it has the advantage of being able to estimate whether the infant's body is ready for toilet training by appropriately visualizing the change in specific gravity of the urine discharged from the infant. Also, when the indicator of the present invention is applied to a disposable diaper for adults, it has the advantage of being able to detect the signs of dehydration by appropriately visualizing the change in specific gravity of the urine discharged from an adult wearer such as a care recipient.

[0054] The indicator of the present invention will be described in more detail below using the indicator 5 of the above-mentioned embodiment.

[0055] [indicator] As described above, indicator 5, one embodiment of the present invention, is adjusted to have an appearance color on the alkaline side in the initial state before contact with urine, and can change color upon contact with urine to a color corresponding to the specific gravity of the urine, and contains a pH indicator, 20% or more by mass of an aliphatic alcohol that is solid at room temperature, and at least one component selected from the group consisting of 10% or more by mass of a hydrophilic polymer and 10% or more by mass of an amine-based cationic surfactant.

[0056] The indicator 5 is adjusted to have an appearance color on the alkaline side in the initial state before contact with urine, but changes color to an appearance color on the acidic side when it comes into contact with urine discharged from a wearer of the disposable diaper 1. At this time, the indicator 5 changes color in different tones depending on the specific gravity value of the urine.

[0057] The degree of coloration of the indicator may be judged by the naked eye, or may be judged by optically measured reflectance, etc. When judging the degree of coloration by the naked eye, for example, it can be judged by comparing the color tone of the indicator with the color tone of a standard color table (i.e., a color sample) prepared in advance with the naked eye. When judging the degree of coloration by optical measurement, it can be judged by processing an image of the indicator taken by a photographing means such as a digital camera or a smartphone with an image processing program installed on an arbitrary computer or smartphone.

[0058] Regarding the color tone of the indicator, the appearance color of the alkaline side and the acidic side is determined by the relative pH relationship before and after coloration due to contact with urine, and the color tone of each appearance color varies depending on the type of pH indicator contained in the indicator. For example, when bromothymol blue is used as the pH indicator, the appearance color of the alkaline side is purple, blue, or blue-green, and the appearance color of the acidic side is yellow-green, yellow, or orange. The indicator of the present invention is different from the conventional color change for detecting the presence or absence of urination (i.e., the color change from the acidic side color of the pH indicator in the indicator to the alkaline side color), and changes from the alkaline side appearance color to the acidic side appearance color according to the urine specific gravity, so that when applied to an absorbent article such as a disposable diaper, the wearer of the absorbent article or his / her assistant can easily recognize the change in urine specific gravity.

[0059] The indicator of the present invention is preferably one that changes color to blue or green when it comes into contact with low specific gravity urine and changes color to yellow or orange when it comes into contact with high specific gravity urine. This indicator changes color to blue or green when it comes into contact with low specific gravity urine and changes color to yellow or orange when it comes into contact with high specific gravity urine, unlike the color change for detecting the presence or absence of urination, i.e., the color change from the acidic side color to the alkaline side color of the pH indicator in the indicator. Therefore, when applied to an absorbent article, the wearer of the absorbent article or his / her assistant can easily recognize the change in urine specific gravity, and in particular, the color change from the initial state before contact with urine to yellow or orange when it comes into contact with high specific gravity urine can be more easily visually recognized. This allows such an indicator to detect the change in urine specific gravity more accurately and more easily.

[0060] Here, the means for adjusting the appearance color of the indicator in its initial state before contact with urine to the alkaline side is not particularly limited, but examples include incorporating an alkalizing agent (e.g., some pH adjusters such as bases, salts, buffers, etc.) that can cause the pH indicator contained in the indicator to appear on the alkaline side.

[0061] (pH indicator) The indicator 5 according to one embodiment of the present invention contains a pH indicator as an essential component. The pH indicator is not particularly limited as long as it can be used as an indicator for absorbent articles, but a pH indicator whose dissociation is promoted by an increase in ionic strength is preferable. Specific examples of such pH indicators include bromothymol blue (BTB), gentian violet, bromocresol purple, malachite green, thymol blue, methyl yellow, bromophenol blue, Congo red, methyl orange, litmus, phenol red, chlorophenol red, neutral red, bromocresol green, methyl red, naphtholphthalein, cresol red, cresolphthalein, phenolphthalein, thymolphthalein, and alizarin yellow R. One type of these pH indicators may be used alone, or two or more types of pH indicators may be used in combination.

[0062] Preferred pH indicators include bromothymol blue (BTB), bromocresol purple, thymol blue, phenol red, chlorophenol red, bromocresol green, methyl red, etc. These pH indicators are preferred because dissociation is promoted by increasing the ionic strength.

[0063] In the indicator of the present invention, it is preferable that the pH indicator contains two or more kinds of pH indicators. By using two or more kinds of pH indicators in combination, it is possible to clearly change color even for urine with a smaller specific gravity difference, so that it is possible to detect changes in urine specific gravity more accurately and more reliably. In addition, by combining two or more kinds of pH indicators with different color change ranges, it is possible to expand the detection range of urine specific gravity, and increase the degree of color change due to changes in urine specific gravity, making it easier to visually recognize.

[0064] When two or more pH indicators are used in combination, a combination of bromothymol blue and another pH indicator is preferred. The use of such a combination as a pH indicator has the advantage that the color tone change during color development can be increased and the color change range can be expanded. Other pH indicators that can be used in combination with bromothymol blue include, for example, thymol blue, phenol red, and methyl red. Among these pH indicators, it is preferred to use methyl red. The combination of bromothymol blue and methyl red can realize a stable and wide color change (color reaction).

[0065] The content of the pH indicator contained in the indicator is not particularly limited, and can be appropriately set in consideration of the responsiveness and visibility of the color reaction. Such a content is, for example, 0.01% by mass to 10.0% by mass, preferably 0.01% by mass to 5.0% by mass, and more preferably 0.05% by mass to 4.0% by mass, based on the total mass (100% by mass) of the indicator composition. When the content of the pH indicator is within such a range, good visibility of the response (coloration) of the indicator can be ensured.

[0066] (Fatty alcohol) Indicator 5, which is one embodiment of the present invention, contains, as an essential component, an aliphatic alcohol that is solid at room temperature (20°C) in a content of 20% by mass or more with respect to the total mass (100% by mass) of indicator 5. By containing such a specific aliphatic alcohol, indicator 5 is less likely to dissolve in moisture such as urine or humidity.

[0067] The aliphatic alcohol that can be used in the indicator of the present invention is not particularly limited as long as it is solid at room temperature and can be used as an indicator for absorbent articles, and examples thereof include aliphatic alcohols having 8 to 34 carbon atoms (C8 to C34). As the aliphatic alcohol, one type of aliphatic alcohol may be used alone, or two or more types of aliphatic alcohols may be used in combination.

[0068] Preferred aliphatic alcohols include those having a melting point of more than 40°C and not more than 110°C, and specific examples include 1-hexadecanol, 1-octadecanol, 1-eicosanol, 1-docosanol, 1-tetracosanol, 1-hexacosanol, 1-octacosanol, and 1,12-dodecanediol. When the aliphatic alcohol contained in the indicator has such a specific melting point, when the indicator composition is applied in a molten state to a substrate such as a nonwoven fabric or film, cooling and solidification proceeds, and the indicator can be formed uniformly at an appropriate position on the substrate. As a result, the indicator containing the specific aliphatic alcohol can detect sodium ions (Na+ ) and potassium ions (K + ), calcium ion (Ca 2+ ), magnesium ion (Mg 2+ ) and even if the color change is small, it is easy to see, allowing for more accurate and reliable detection of changes in urine specific gravity.

[0069] The content of the aliphatic alcohol contained in the indicator is not particularly limited as long as it is 20% by mass or more relative to the total mass (100% by mass) of the indicator, and can be appropriately set in consideration of the resistance to dissolution in moisture such as urine or moisture, visibility, etc. Such a content is, for example, 20% by mass to 80% by mass, and preferably 30% by mass to 60% by mass, relative to the total mass (100% by mass) of the indicator composition.

[0070] (Hydrophilic polymer) Indicator 5, which is one embodiment of the present invention, contains at least one of 10% by mass or more of a hydrophilic polymer and 10% by mass or more of an amine-based cationic surfactant as essential components. By containing a predetermined amount of such components, indicator 5 becomes highly responsive in changing color to changes in urine specific gravity when it comes into contact with urine, and can clearly change color even when the change in urine specific gravity is small.

[0071] The hydrophilic polymer that can be used in the indicator of the present invention is not particularly limited as long as it is a polymer having hydrophilicity, and examples thereof include polyamide, cellulose-based polymer (e.g., cellulose, cellulose derivatives, etc.), acrylic polymer (e.g., polyacrylic acid, polyacrylamide, maleic anhydride polymer, etc.), polyol (e.g., polyethylene glycol, etc.), polyvinylpyrrolidone, polyvinyl alcohol, polyallylamine, polyethyleneimine, oxazoline-based polymer (e.g., poly(2-oxazoline), poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), etc.). As the hydrophilic polymer, one type of hydrophilic polymer may be used alone, or two or more types of hydrophilic polymers may be used in combination.

[0072] In this specification, in order to distinguish between a hydrophilic polymer and a polymer of a sugar alcohol which is a sugar alcohol component described later, the hydrophilic polymer excludes a polymer of a sugar alcohol.

[0073] In the indicator of the present invention, it is preferable that the indicator contains polyamide as a hydrophilic polymer. When the indicator contains polyamide as a hydrophilic polymer, it acts on the morphological change of the pH indicator, widens the range of color change of urine specific gravity, and has a strong dissolving effect and a fast response speed. As a result, the indicator containing polyamide as a hydrophilic polymer can accurately detect a wide range of changes in urine specific gravity. In addition, the polyamide preferably has a softening point of 140°C or less.

[0074] The content of the hydrophilic polymer contained in the indicator is not particularly limited as long as it is 10% by mass or more relative to the total mass (100% by mass) of the indicator, and can be appropriately set in consideration of the responsiveness of the color reaction, visibility, etc. Such a content is, for example, 10% by mass to 40% by mass, and preferably 15% by mass to 30% by mass, relative to the total mass (100% by mass) of the indicator composition.

[0075] (Amine-based cationic surfactant) The amine-based cationic surfactant that can be used in the indicator of the present invention is not particularly limited as long as it is an amine-based surfactant having a cationic hydrophilic group, and examples thereof include quaternary ammonium salt-type cationic surfactants, alkylamine salt-type surfactants, and cationic surfactants having a pyridine ring.

[0076] Specific examples of the quaternary ammonium salt type cationic surfactant include tetramethylammonium chloride, tetramethylammonium hydroxide, tetrabutylammonium chloride, dodecyldimethylbenzylammonium chloride, alkyltrimethylammonium chloride, octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, alkyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, benzalkonium chloride, benzalkonium bromide, benzethonium chloride, dialkyldimethylammonium chloride, didecyldimethylammonium chloride, and distearyldimethylammonium chloride.

[0077] Specific examples of the alkylamine salt type cationic surfactant include monomethylamine hydrochloride, dimethylamine hydrochloride, and trimethylamine hydrochloride.

[0078] Specific examples of the cationic surfactant having a pyridine ring include butylpyridinium chloride, dodecylpyridinium chloride, and cetylpyridinium chloride.

[0079] The above cationic surfactants may be used alone or in combination of two or more kinds.

[0080] In the indicator of the present invention, it is preferable that the amine cationic surfactant contains a quaternary ammonium salt. When the amine cationic surfactant contains a quaternary ammonium salt, the surfactant has high surface activity and the indicator changes color faster when it comes into contact with urine. As a result, the indicator containing a quaternary ammonium salt as the cationic surfactant can detect the change in urine specific gravity with higher accuracy.

[0081] The content of the cationic surfactant contained in the indicator is not particularly limited as long as it is 10% by mass or more relative to the total mass (100% by mass) of the indicator, and can be appropriately set in consideration of the responsiveness of the color reaction, visibility, etc. Such a content is, for example, 10% by mass to 40% by mass, and preferably 15% by mass to 30% by mass, relative to the total mass (100% by mass) of the indicator composition.

[0082] (Sugar alcohol component) The indicator 5 according to one embodiment of the present invention further contains a sugar alcohol component as an optional component. As in this embodiment, the indicator of the present invention preferably further contains at least one component selected from sugar alcohol and sugar alcohol polymer as the sugar alcohol component at a blending ratio of 2.5% by mass or more. Although the sugar alcohol component is not an essential component in the indicator of the present invention, when the indicator contains such a sugar alcohol component, the hydrophilicity is increased, and the color change speed when the indicator comes into contact with urine can be increased.

[0083] Examples of sugar alcohol components that can be used in the indicator of the present invention include sugar alcohols and their polymers, specifically, sugar alcohols such as glycerin, erythritol, D-threitol, L-threitol, D-arabinitol, L-arabinitol, xylitol, ribitol, D-iditol, galactitol, mannitol, volemitol, and perseitol, and polymers of these sugar alcohols. Preferred sugar alcohol components include glycerin and its polymer, polyglycerin. These sugar alcohol components may be used alone, or two or more types of sugar alcohol components may be used in combination.

[0084] The content of the sugar alcohol component contained in the indicator is not particularly limited as long as it is 2.5% by mass or more relative to the total mass (100% by mass) of the indicator, and can be appropriately set in consideration of the responsiveness of the color reaction, visibility, etc. Such a content is, for example, 2.5% by mass to 20% by mass, and preferably 3.0% by mass to 15.0% by mass, relative to the total mass (100% by mass) of the composition for indicator.

[0085] (Hydrophobic component) The indicator 5 according to one embodiment of the present invention further contains a hydrophobic component such as wax, oil, or tackifier resin as a plasticizer or tackifier. As in this embodiment, the indicator of the present invention preferably further contains at least one component selected from the group consisting of wax, oil, and tackifier resin as a hydrophobic component. Although the hydrophobic component is not an essential component in the indicator of the present invention, if the indicator contains such a hydrophobic component, the indicator composition is more easily fixed to the substrate when applied to a substrate such as a nonwoven fabric or film, and the indicator can be accurately formed at a predetermined position on the substrate. As a result, an indicator containing such a hydrophobic component can detect changes in urine specific gravity more accurately and reliably.

[0086] The wax that can be used in the indicator of the present invention is not particularly limited as long as it can act as a plasticizer, and examples thereof include known natural waxes and synthetic waxes. Specific examples of natural waxes include petroleum-derived waxes such as paraffin and microcrystalline wax (microcrystalline wax); animal-derived waxes such as beeswax and spermaceti; plant-derived waxes such as carnauba wax; and mineral-derived waxes such as montan wax and ozokerite. Specific examples of synthetic waxes include polyethylene wax, Fischer-Tropsch wax, and fatty acid amides. Preferred waxes include petroleum-derived waxes such as paraffin and microcrystalline wax.

[0087] The oil that can be used in the indicator of the present invention is not particularly limited as long as it can act as a plasticizer, and examples thereof include known paraffinic oils, naphthenic oils, aromatic oils, etc. Preferred oils include naphthenic oils.

[0088] The tackifier resin that can be used in the indicator of the present invention is not particularly limited as long as it can act as a tackifier, and examples thereof include known natural resins and petroleum-based resins. Specific examples of natural resins include plant-derived resins such as rosin and rosin derivatives, terpene and modified terpene. Specific examples of petroleum-based resins include C5-C9 aliphatic or aromatic resins, and C5-C9 aliphatic and aromatic copolymer resins.

[0089] The above hydrophobic components may be used alone as one type of hydrophobic component, or in combination of two or more types of hydrophobic components.

[0090] The content of the hydrophobic component contained in the indicator is not particularly limited as long as it does not impair the effects of the present invention, but is, for example, 0.1% by mass to 30.0% by mass, and preferably 1.0% by mass to 20.0% by mass, relative to the total mass (100% by mass) of the indicator.

[0091] (Alkalizing agent) The indicator 5 according to one embodiment of the present invention further contains an alkalizing agent as an optional component. By containing such an alkalizing agent, the indicator 5 is less likely to have uneven color tone before and after color change due to contact with urine, and the color change is more easily visible.

[0092] In the indicator 5, the alkalizing agent is also used as a means for adjusting the external color of the indicator 5 in its initial state before contact with urine to the alkaline side.

[0093] The alkalizing agent that can be used in the indicator of the present invention is not particularly limited, but examples thereof include known sodium carbonate (Na2CO3), sodium hydroxide (NaOH), potassium carbonate (K2CO3), and the like.

[0094] The indicator of the present invention preferably further contains sodium carbonate as an alkalizing agent. Sodium carbonate is more easily mixed uniformly with other components in the indicator than other alkalizing agents such as sodium hydroxide and potassium carbonate, so unevenness or abnormal color change is less likely to occur, and even if the color change is small, the color change is easily visible. As a result, the indicator containing sodium carbonate as an alkalizing agent can detect changes in urine specific gravity more accurately and reliably.

[0095] (Other added ingredients) The indicator of the present invention may further contain any additive component that can be used in an indicator for absorbent articles. Such additive components include, but are not limited to, antioxidants, light stabilizers, antibacterial agents, fragrances, etc.

[0096] The indicator composition comprising the above-mentioned components can be produced by mixing them using any suitable heat-melting means, although there is no particular limitation thereto.

[0097] The indicator of the present invention is not limited to the above-described embodiment or the examples described below, and can be appropriately combined, substituted, modified, etc., without departing from the purpose and spirit of the present invention. EXAMPLES

[0098] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

[0099] Example 1 A composition for indicator was obtained by mixing 1-docosanol as an aliphatic alcohol, a quaternary ammonium salt as an amine-based cationic surfactant, a polyamide as a hydrophilic polymer with a softening point of about 120°C, methyl red and BTB as pH indicators, sodium carbonate as an alkalizing agent, glycerin as a sugar alcohol component, and naphthenic oil as a hydrophobic component in the formulation shown in Table 1 below. Next, this composition for indicator was melted and applied to the surface of a sheet-like substrate for forming a back sheet of a disposable diaper, and further cooled and solidified to produce the indicator of Example 1.

[0100] Examples 2 to 5 Indicators of Examples 2 to 5 were produced in the same manner as in Example 1, except that the blending ratios and types of various components were changed as shown in Table 1 below.

[0101] The indicators of Examples 1 to 5 were evaluated for their responsiveness to changes in urine specific gravity according to the following various evaluation methods (i.e., evaluation of color change, evaluation of color change speed, and evaluation of retention after urination (after absorption)). The evaluation results of the formulations of the indicators of Examples 1 to 5 and their responsiveness to changes in urine specific gravity are shown in Table 1 below.

[0102] <Discoloration evaluation> The indicator to be evaluated was attached to a 6 mm wide, 20 g / m2 leak-proof film (polyethylene film) commonly used for the backsheet of disposable diapers. 2 A test piece for evaluating discoloration is prepared by applying a line of the coating weight of 100g / g. A filter paper (Advantec Qualitative Filter Paper No. 2, manufactured by Toyo Roshi Co., Ltd. (corresponding to type 2 specified in JIS P 3801 [filter paper (for chemical analysis)])) is placed on the prepared test piece indicator. Prepare multiple types of urine with specific gravities ranging from 1.000 to 1.045, and drop 2 mL of urine of each specific gravity onto a filter paper placed on the indicator to be evaluated. The filter paper is removed 15 minutes after dropping, and the indicator color change is evaluated by comparing it with the color sample. If a color change with a difference in urine specific gravity of 0.005 can be distinguished, it is evaluated as "O" (a difference in urine specific gravity can be detected with high accuracy), and if a color change with a difference in urine specific gravity of 0.010 can be distinguished, it is evaluated as "X" (a difference in urine specific gravity cannot be detected with high accuracy).

[0103] <Evaluation of discoloration speed> Urine is placed in contact with the indicator to be evaluated, and the color of the indicator after one minute (the color after discoloration due to urine) is compared with the color of the indicator after 10 minutes using a color sample to evaluate the identity of the two colors. If the two colors are the same, they are rated as "◎" (complete color change within one minute, i.e. very fast color change), if the colors are almost the same, they are rated as "〇" (almost color change within one minute, i.e. fast color change), if the colors are similar, they are rated as "△" (a certain amount of color change within one minute, i.e. relatively fast color change), and if the colors are different, they are rated as "×" (not color change within one minute, i.e. slow color change).

[0104] <Evaluation of retention after urination (after absorption)> The indicator to be evaluated is brought into contact with urine, and the color of the indicator after three hours (the color after discoloration due to urine) is evaluated as to whether it can be visually confirmed. If the color of the indicator can be clearly confirmed after three hours, it is rated as "○" (very difficult to dissolve in water such as urine or moisture), if the color of the indicator can be confirmed after three hours, it is rated as "△" (difficult to dissolve in water such as urine or moisture), and if the color of the indicator cannot be confirmed after three hours, it is rated as "×" (easily dissolves in water such as urine or moisture).

[0105] [Table 1]

[0106] As shown in Table 1, it was found that the indicators of Examples 1 to 5 were capable of detecting changes in urine specific gravity with high accuracy, and were also less likely to dissolve in water such as urine or humidity. [Explanation of symbols]

[0107] 1. Disposable diapers 2 Surface sheet 3 Back sheet 4. Absorber 4A Absorption Core 4B Core Wrap Sheet 5. Indicators

Claims

1. An indicator for an absorbent article, comprising: the indicator is adjusted to have an appearance color on the alkaline side in an initial state before contacting with urine, and is capable of changing color to a color corresponding to the specific gravity of urine upon contact with urine; A pH indicator; 20% by mass or more of an aliphatic alcohol that is solid at room temperature; At least one of 10% by mass or more of a hydrophilic polymer and 10% by mass or more of an amine-based cationic surfactant; An indicator comprising:

2. 2. The indicator according to claim 1, wherein the aliphatic alcohol has a melting point greater than 40°C and less than or equal to 110°C.

3. 3. The indicator according to claim 1, wherein the hydrophilic polymer comprises a polyamide.

4. 4. The indicator according to claim 1, wherein the amine-based cationic surfactant contains a quaternary ammonium salt.

5. The indicator according to any one of claims 1 to 4, characterized in that the pH indicator comprises two or more types of pH indicators.

6. The indicator according to any one of claims 1 to 5, further comprising at least one of a sugar alcohol and a sugar alcohol polymer as a sugar alcohol component in a blending ratio of 2.5 mass% or more.

7. The indicator according to any one of claims 1 to 6, further comprising at least one component selected from the group consisting of wax, oil and tackifier resin as a hydrophobic component.

8. The indicator according to any one of claims 1 to 7, further comprising sodium carbonate as an alkalizing agent.

9. The indicator according to any one of claims 1 to 8, characterized in that the indicator changes color to blue or green when it comes into contact with urine of low specific gravity, and changes color to yellow or orange when it comes into contact with urine of high specific gravity.

10. An absorbent article comprising the indicator according to any one of claims 1 to 9.

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