Composition, pH testing tool, and method for manufacturing the pH testing tool

Abstract

The testing equipment described in certain literature required the selection of a highly absorbent material as the substrate, which limited the choice of substrate. [Solution] According to one aspect of the present invention, a composition for testing the pH of a test solution is provided, comprising a water-soluble polymer and a pH indicator, wherein the water-soluble polymer has an aqueous solution viscosity (4% by mass, 20°C) of 60 mPa·s or more and 10,000 mPa·s or less, as measured by a coaxial double-cylinder rotational viscometer as defined in JIS Z 8803:2011.

Description

Technical Field

[0001] The present invention relates to a composition, a pH test tool, and a method for producing a pH test tool.

Background Art

[0002] In order to confirm the health state of a living body, there is a method of measuring the pH of a biological sample such as urine or blood. For example, cats are prone to urinary system diseases, and the signs thereof tend to appear in the pH of urine. Therefore, measuring the pH of urine is useful as a simple evaluation method for the health state of cats. In order to easily perform pH measurement of a biological sample at home, a test tool for detecting the pH of a biological sample as described in, for example, Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the test tool as described in Patent Document 1 requires selection of a highly absorbent material as a base material, and there are restrictions on the selection of the base material.

Means for Solving the Problems

[0005] According to one aspect of the present invention, there is provided a composition for testing the pH of a test liquid, the composition containing a water-soluble polymer and a pH indicator, wherein the water-soluble polymer has an aqueous solution viscosity (4 mass%, 20°C) of 60 mPa·s or more and 10000 mPa·s or less as measured by a coaxial double cylindrical rotational viscometer specified in JIS Z 8803:2011.

[0006] According to this embodiment, it is possible to provide a composition, etc., that can be used to create a testing device that holds the test solution and displays the pH, regardless of the type of substrate. [Brief explanation of the drawing]

[0007] [Figure 1] These are side views (Figure 1(A)) and cross-sectional views (Figure 1(B)) of the pH testing device. [Figure 2] This diagram illustrates the hue circle and hue differences of the 20 colors in the Munsell color system. [Figure 3] This figure shows the state of the cups in Example 1 and Comparative Example 3 30 minutes after adding the test solutions with different pH levels. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described below. For each numerical range presented herein, the proportion of the composition, etc. that satisfies the numerical range may be preferably about 85% or more, more preferably about 90% or more, even more preferably about 95% or more, or 100%.

[0009] [pH testing equipment] First, let's describe a pH testing device 1 according to one embodiment. Figure 1 shows a side view (Figure 1(A)) and a cross-sectional view (Figure 1(B)) of the pH testing device. The pH testing tool 1 (composition) is used to test the pH of a test solution. The external shape of the pH testing tool 1 is not limited to cylindrical particulate form as shown in Figure 1(A), as long as it can test the pH of the test solution. For example, the pH testing tool 1 (base material 11) may be in the form of other particulate shapes such as prismatic, spherical, conical, or pyramidal shapes, or it may be in the form of a sheet, rod, etc.

[0010] The pH testing device 1 comprises a base material 11 and a composition layer 12 provided on the surface of the base material 11. The composition layer 12 is provided so as to cover at least a portion of the surface of the base material 11, preferably covering 50% or more of the surface of the base material 11, more preferably covering 80% or more, and particularly preferably covering 100%. This makes it easy for the test solution to come into contact with the composition layer 12. The composition layer 12 is mainly composed of a composition supported on the base material 11. The composition contains a water-soluble polymer and a pH indicator. Thus, because the composition layer 12 contains a water-soluble polymer, the composition layer 12 itself can hold the test solution, eliminating the need for the substrate 11 to be a highly absorbent material. Furthermore, by including a pH indicator, the pH of the test solution can be easily determined by its appearance (hue).

[0011] The base material 11 can be appropriately selected according to the application of the pH testing device 1, such as the type of test solution and the method of supplying the test solution to the pH testing device 1. The constituent materials of the base material 11 may be hydrophilic inorganic substances, organic substances, or composites thereof. Examples of inorganic substances include oxides such as alumina (Al2O3), silica (SiO2), calcium oxide (CaO), and zeolites; nitrides such as aluminum nitride (AlN) and silicon nitride (Si3N4); carbides such as silicon carbide (SiC); metals such as aluminum (Al), iron (Fe), and stainless steel (e.g., SUS304); and natural minerals such as bentonite, kaolin, and talc. Examples of organic substances include synthetic polymers such as polyurethane (PU), polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET); natural polymers such as cellulose, keratin, and lignin; and natural materials such as plants (stems, leaves, fruits, roots, wood, etc.), animals (hair), cocoons, and feathers. Thus, the base material 11 can be constructed using various types of materials.

[0012] In particular, the base material 11 is preferably a paper base material whose constituent materials include pulp or recycled paper containing cellulose as the main component. By using a paper base material in this way, the total mass of the pH testing tool 1 can be reduced, and the environmental burden associated with the manufacture, distribution, and disposal of the pH testing tool 1 is reduced. In addition, because the quality does not easily change, the pH testing tool 1 can be stored for a long period of time. Furthermore, such a pH testing tool 1 can be manufactured easily and inexpensively.

[0013] The test solution for pH testing device 1 is not particularly limited, but it is preferably a hydrophilic liquid. The test solution may be, for example, a liquid of biological origin (biological sample), or a non-biological liquid such as water (e.g., purified water, sewage, spring water, groundwater, river water, lake water, seawater), a hydrophilic organic substance or aqueous solution thereof (e.g., acetic acid, ethanol, glycerin), or an aqueous solution of a hydrophilic inorganic substance (e.g., urea, sodium chloride). Because the test solution is hydrophilic, the affinity between the test solution and the composition layer 12 containing the water-soluble polymer becomes sufficiently high. As a result, the composition layer 12 can adequately retain the test solution, and the test solution can react with the pH indicator, allowing the pH indicator to appropriately display the pH of the test solution.

[0014] However, the test solution is preferably a biological fluid (biological sample), such as a fluid derived from an animal (especially a mammal), a plant, or a microorganism. Examples of animal-derived fluids include excretions such as urine and feces, secretions such as sweat, saliva, tears, nasal secretions, gastric juice, bile, pancreatic juice, vaginal secretions, and semen, circulatory fluids such as blood and lymph, cerebrospinal fluid, bone marrow fluid, joint fluid, pleural fluid, and ascites. Examples of plant-derived fluids include secretions such as rhizosphere sap, pollen, and resin, xylem sap, leaf tissue sap, fruit juice, and complex extracts such as leaf extracts, stem extracts, flower extracts, and root extracts. Examples of microorganism-derived fluids include cytoplasm, mycelium, and culture media containing their metabolites. In this way, by using a biological fluid as the test solution, abnormalities in its pH can be detected, leading to the discovery of problems such as diseases and high-stress states.

[0015] In particular, the test solution preferably contains mammalian urine. Since the pH of urine is usually around 6, abnormalities can be easily detected using the pH testing device 1, as described later. By placing the pH testing device 1 in the excretory area (toilet) of a human, pet, or livestock, diapers, urine collection container, etc., urine can be easily collected as it is adsorbed onto the water-soluble polymer. Furthermore, as described later, the water-soluble polymer has an appropriate viscosity, which allows it to retain the urine and pH indicator while maintaining the state in which the composition layer 12 is supported on the substrate 11. Therefore, when the composition layer 12 comes into contact with the test solution, it is possible to prevent color transfer to the surroundings due to the leakage of the pH indicator and to continuously display the pH of the test solution. In particular, cats, being mammals, have the characteristic of urinating in sand. By mixing pH testing device 1 into the litter box that the individual cat is accustomed to, the urine used as the test solution can be brought into contact with pH testing device 1 without arousing suspicion.

[0016] The pH detection capability of the pH testing device 1 will be explained with reference to Figure 2. Figure 2 is a diagram illustrating the 20-color hue circle and hue difference of the Munsell color system. In this specification, when "hue circle" refers to the 20-color hue circle 2 of the Munsell color system shown in Figure 2. When "hue difference" refers to the smaller angle θ between the corresponding hues (5YR and 5GY in Figure 2) 21 on the hue circle 2.

[0017] It is preferable that the hue difference θ between the hue 21 when urine of pH 5 is applied as a test liquid and the hue 21 when urine of pH 7 is applied to the pH test tool 1 is approximately 36° or more and 180° or less on the 20-hue color circle 2 of the Munsell color system, more preferably 54° or more and 180° or less, and particularly preferably 72° or more and 180° or less. As described above, by having a sufficiently large hue difference θ between pH 5 and pH 7, particularly when the pH of a biological-derived liquid deviates from the normal value, the abnormality can be easily and clearly presented only by visual observation. Therefore, for example, when the pH of urine, cerebrospinal fluid, blood, bone marrow fluid or the like whose normal value is approximately pH 6 or more and 7 or less shifts to acidic or alkaline, the pH test tool 1 exhibits a hue 21 different from the normal pH, whereby the possibility of serious diseases such as kidney disease, meningitis, diabetes and sepsis can be quickly detected.

[0018] [Composition] More specifically, the pH of the test liquid can be tested by the pH indicator in the composition constituting the composition layer 12 supported on the base material 11 shown in FIG. 1(B).

[0019] (pH Indicator) It is preferable that the hue difference θ between the hue 21 when its aqueous solution is adjusted to pH 5 and the hue 21 when adjusted to pH 7 is approximately 54° or more and 180° or less on the 20-hue color circle 2 of the Munsell color system shown in FIG. 2, and more preferably 72° or more and 180° or less. As described above, since the hue difference θ in the aqueous solution of the pH indicator is sufficiently large, even when the water-soluble polymer in the base material 11 or the composition layer 12 is colored, the distribution of the pH indicator in the composition layer 12 has a slight bias, or the amount of the test liquid is slightly insufficient, the entire pH test tool 1 can exhibit the hue difference θ as described above.

[0020] Further, the pH indicator preferably includes a range of about pH 5 or more and 7 or less in its color change interval, and more preferably includes a range of about pH 4.5 or more and pH 7.5 or less. Having such a color change interval makes it possible to suitably detect pH abnormality particularly when the test liquid is a mammal-derived liquid such as urine, cerebrospinal fluid, blood, or bone marrow fluid. More specifically, the pH indicator includes, for example, indicators such as thymol blue, phenolphthalein, tropeolin OO, cresol red, phenol red, neutral red, bromothymol blue (hereinafter also referred to as "BTB"), bromocresol purple, bromophenol red, p-nitrophenol, methyl red (hereinafter also referred to as "MR"), bromocresol green, tetrabromophenol blue, chlorophenol red, methyl orange, ethyl orange, bromophenol blue, brilliant yellow, Congo red, bromocresol blue, and anthocyanin.

[0021] Among these, the pH indicator preferably contains two or more indicators having a color change interval of about pH 4 or more and pH 8 or less, such as BTB, MR, bromocresol green, chlorophenol red, bromocresol purple, neutral red, and anthocyanin. By using such general-purpose indicators, the pH test tool 1 can be produced easily and inexpensively. In addition, since the indicators have relatively low biotoxicity and sufficiently develop color even at low concentrations, the impact on the living organism to be tested can be kept low particularly when the test liquid is derived from a living organism. Furthermore, the use of two or more indicators facilitates achieving the color change interval as described above.

[0022] In particular, the pH indicator preferably contains BTB and MR. As such, by using BTB, which changes from yellow to blue as pH increases, and MR, which changes from red to yellow, the composition can exhibit a sufficiently large hue difference θ (see Figure 2) at pH 5 and pH 7. Furthermore, the mass ratio of BTB to MR is preferably between 0.1 and 10, and more preferably between 0.5 and 8. By mixing in such proportions, the hue difference θ described above can be achieved.

[0023] (Water-soluble polymer) The mass ratio of the water-soluble polymer to the pH indicator is preferably 3 to 12,000, more preferably 5 to 10,000, and even more preferably 10 to 5,000. By incorporating an appropriate amount of pH indicator in this way, it reacts with the test solution, allowing the pH test tool 1 to exhibit the correct hue 21. Furthermore, by incorporating a sufficient amount of water-soluble polymer, the water-soluble polymer can retain the pH indicator, preventing its leakage. In addition, the adhesion of the composition layer 12 to the substrate 11 is easily maintained.

[0024] The water-soluble polymer is preferably such that its aqueous solution viscosity (4% by mass, 20°C) measured by a coaxial double-cylinder rotational viscometer as specified in JIS Z 8803:2011 is approximately 60 mPa·s to 10,000 mPa·s, more preferably 80 mPa·s to 9,000 mPa·s, and even more preferably 100 mPa·s to 8,000 mPa·s. In this specification, the coaxial double-cylinder rotational viscometer is a coaxial double-cylinder rotational viscometer of the constant-speed inner cylinder type.

[0025] Thus, by having a sufficiently high viscosity, the water-soluble polymer can retain the pH indicator, preventing or suppressing the dissipation of the pH indicator when the test solution is added. As a result, the pH indicator and the test solution can react sufficiently in the composition layer 12 of the pH test device 1, and the pH of the test solution can be appropriately displayed. Furthermore, since the composition layer 12 (water-soluble polymer) can be supported on the substrate 11 in Figure 1(B) with sufficient adhesion, the composition layer 12 is less likely to peel off from the substrate 11 during storage, distribution, etc., of the pH test device 1.

[0026] Furthermore, because the viscosity of the water-soluble polymer is not too high, the composition layer 12 can exhibit sufficient affinity for the test solution. That is, the test solution dissolves in the composition layer 12, and the test solution and pH indicator react sufficiently, allowing the pH test device 1 to exhibit the correct hue 21. When mixing the water-soluble polymer and pH indicator to obtain the composition, or when supporting the composition on the substrate, extremely large forces are not required. This reduces energy consumption when manufacturing the pH test device 1. It also reduces the technical difficulty of manufacturing.

[0027] The water-soluble polymer preferably contains one or more of the following: polyvinyl alcohol (hereinafter also referred to as "PVA"), poly(meth)acrylic acid, polyacrylamide, synthetic water-soluble resins such as polyethylene oxide, modified starch, cellulose derivatives, etc. The water-soluble polymer preferably contains synthetic water-soluble resins, in which case it is easier to adjust its properties such as water solubility and viscosity to desired values.

[0028] In particular, the water-soluble polymer preferably contains a vinyl alcohol-based polymer (hereinafter also simply referred to as "PVA"). Since PVA has high water solubility, it can sufficiently increase the affinity between the test solution and the composition layer 12. Furthermore, because it has excellent adhesion to hydrophilic materials, hydrophilic materials other than plastics, such as paper as described above, can be used as the material for the substrate 11. In addition, desired properties can be easily achieved by adjusting parameters such as viscosity-average degree of polymerization, degree of saponification, and copolymer components.

[0029] The viscosity-average degree of polymerization of PVA, as measured by the method described in JIS K 6726:1994, is preferably between 1500 and 6000, and more preferably between 1600 and 5000. Having such a viscosity-average degree of polymerization makes it possible to achieve the appropriate viscosity described above. More specifically, the "viscosity-average degree of polymerization" is a value calculated from the intrinsic viscosity [η] (g / dL) measured at 30°C using an Ostwald viscometer with deionized water as the solvent, using the following formula (2). log(P)=1.613×log([η]×104 / 8.29) ···(2) Here, P represents the viscosity-average degree of polymerization.

[0030] Furthermore, the degree of saponification of PVA, as measured by the method described in JIS K 6726:1994, is preferably 65 mol% to 98 mol%, and more preferably 80 mol% to 95 mol%. Having such a degree of saponification provides the composition with high hydrophilicity, allowing the composition layer 12 and the test solution to dissolve sufficiently, so that the pH test device 1 can exhibit the correct color 21.

[0031] PVA is a saponified polymer obtained by polymerizing raw material monomers containing vinyl ester monomers. Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, or mixtures thereof. It is preferable that the vinyl ester monomer contains vinyl acetate.

[0032] Furthermore, the PVA raw material monomer may further contain other monomers copolymerizable with vinyl ester monomers. Other monomers include, for example, α-olefin monomers such as ethylene and propylene; alkyl (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; unsaturated amide monomers such as (meth)acrylamide and N-methylolacrylamide; unsaturated carboxylic acid monomers such as (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid; alkyl (methyl, ethyl, propyl, etc.) ester monomers of unsaturated carboxylic acids; anhydrides of unsaturated carboxylic acids such as maleic anhydride; salts of unsaturated carboxylic acids with inorganic substances such as sodium, potassium, and ammonium; glycidyl group-containing monomers such as allyl glycidyl ether and glycidyl (meth)acrylate; sulfonic acid group-containing monomers or salts thereof such as 2-acrylamido-2-methylpropanesulfonic acid; phosphate group-containing monomers such as acid phosphooxyethyl methacrylate and acid phosphooxypropyl methacrylate; pro Examples include alkyl vinyl ether monomers such as polyvinyl vinyl ether, butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, heptyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, undecyl vinyl ether, dodecyl vinyl ether, tridecyl vinyl ether, tetradecyl vinyl ether, pentadecyl vinyl ether, hexadecyl vinyl ether, heptadecyl vinyl ether, octadecyl vinyl ether, nonadecyl vinyl ether, and eicosyl vinyl ether; and polyfunctional monomers such as ethanediol divinyl ether, propanediol divinyl ether, butanediol divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, polypropylene glycol divinyl ether, diallylmethyl isocyanurate, and triallyl isocyanurate.

[0033] In this specification, when "(meth)acryloyl," "(meth)acrylic," "(meth)acrylic acid," "(meth)acrylate," or "(meth)acrylamide" is used, unless otherwise specified, it shall refer to "acryloyl and / or methacryloyl," "acrylic and / or methacrylic," "acrylic acid and / or methacrylic acid," "acrylate and / or methacrylate," or "acrylamide and / or methacrylamide," respectively.

[0034] Furthermore, when copolymerizing PVA with monomers other than vinyl ester monomers, it is preferable to include at least one of either hydrophobic group-modified PVA copolymerized with alkyl vinyl ether monomers, or crosslinked PVA copolymerized with polyfunctional monomers. This makes it easier to adjust the viscosity of the PVA-containing water-soluble polymer to the range described above.

[0035] The method for producing PVA is not particularly limited, and for example, solution polymerization, suspension polymerization, bulk polymerization, etc., can be employed. Among these, solution polymerization in a solvent is preferred, as this method is easy to operate and facilitates the subsequent saponification reaction.

[0036] Saponification can be carried out by dissolving a polymer containing vinyl ester monomer units (vinyl ester polymer) in an alcohol and adding an alkaline catalyst or an acid catalyst. Examples of alcohols include methanol, ethanol, and butanol. The concentration of the vinyl ester polymer in the alcohol is preferably between 5% and 80% in terms of solid content. As the alkaline catalyst, for example, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, and potassium methylate, or alkaline catalysts such as alkoxides can be used. As the acid catalyst, for example, aqueous solutions of inorganic acids such as hydrochloric acid and sulfuric acid, or organic acids such as p-toluenesulfonic acid can be used. The amount of these catalysts used is preferably between 0.1 mmol equivalent and 100 mmol equivalent per unit of vinyl ester monomer. The reaction temperature during saponification is preferably in the range of 10°C to 70°C, and more preferably in the range of 30°C to 50°C. The reaction time is preferably between 1 hour and 10 hours. By carrying out the saponification reaction under these conditions, PVA can have the preferred degree of saponification described above.

[0037] (Other ingredients) The composition layer 12 of the pH testing device 1 shown in Figures 1(A) and 1(B) may contain components other than pH indicators and water-soluble polymers. For example, the composition may contain chelating agents, buffering agents, stabilizers, surfactants, antibacterial agents, solubilizers, pH adjusters, and the like.

[0038] Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA). By adding a chelating agent, it is possible to prevent or suppress the interference of metal ions and other substances in the test solution from inhibiting the proper color development (presentation of hue 21) of the pH indicator. Examples of buffering agents include salts of acids such as sodium acetate, sodium citrate, and ammonium acetate, and salts of bases such as sodium bicarbonate and ammonium bicarbonate. Adding a buffering agent helps stabilize the display of hue 21 in the pH indicator.

[0039] Examples of stabilizers include glycerol, polyethylene glycol (PEG), trehalose, and sorbitol. Adding stabilizers makes it easier to maintain the quality of the pH testing device 1. Examples of surfactants include sodium cholate and lecithin. Examples of antibacterial agents include sodium azide, propylene glycol, sodium benzoate, and potassium sorbate. Examples of solubilizers include cyclodextrin and polyvinylpyrrolidone (PVP). Examples of pH adjusters include sodium acetate and sodium bicarbonate.

[0040] Furthermore, the composition may further contain an ingredient indicator, to the extent that it does not inhibit the color development of the pH indicator. Examples of ingredient indicators include those that can detect the presence or concentration of health indicators such as glucose, protein, occult blood, urea, and specific gravity, and produce a color change.

[0041] [Method of manufacturing inspection tools] Next, a method for manufacturing a pH testing device 1 for testing the pH of a test solution will be described. The manufacturing method includes the steps of preparing a base material 11, a water-soluble polymer having an aqueous solution viscosity (4% by mass, 20°C) of approximately 60 mPa·s to 10,000 mPa·s as measured by a coaxial double-cylindrical rotational viscometer specified in JIS Z 8803:2011, and a pH indicator, and applying a liquid composition containing the water-soluble polymer and the pH indicator to the base material 11, drying it to form a composition layer 12, and obtaining the pH testing device 1.

[0042] [1] First, prepare the base material 11, the water-soluble polymer, and the pH indicator. The base material 11 and pH indicator may be prepared by purchasing commercially available products or by manufacturing them anew. On the other hand, water-soluble polymers can be produced by polymerization and saponification, as described above for PVA.

[0043] [2] Next, a water-soluble polymer and a pH indicator are dissolved in water to obtain a liquid composition. The liquid composition preferably has a pH of approximately 4 to 8, and more preferably 5 to 7. By setting the pH of the liquid composition within this range beforehand, the pH of the composition layer 12 obtained by drying the liquid composition becomes approximately equivalent to the normal pH of a test solution of biological origin. As a result, an abnormality can be recognized by the change in color of the pH testing device 1 (composition layer 12).

[0044] The content of the water-soluble polymer in the liquid composition is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 12% by mass or less. By keeping the content of the water-soluble polymer not too high, the energy consumption during dissolution and mixing can be reduced. In addition, the liquid composition can be easily applied to the substrate 11 with an appropriate thickness. Furthermore, a sufficiently high content of the water-soluble polymer allows the liquid composition to exhibit an appropriate viscosity, enabling it to be supported on the substrate 11. Furthermore, the content of the pH indicator in the liquid composition is preferably 0.001% by mass or more and 1% by mass or less, and more preferably 0.01% by mass or more and 0.8% by mass or less. By dissolving the pH indicator in such a content, it develops a suitable color when it reacts with the test solution, allowing the pH test device 1 to exhibit a good hue 21.

[0045] [3] Next, the liquid composition is applied to the substrate 11. The method of applying the liquid composition is not particularly limited, but examples include immersing the substrate 11 in the liquid composition, pouring the liquid composition from above the substrate 11, spraying the liquid composition onto the substrate 11, or applying the liquid composition to the substrate 11 with an application tool such as a brush or spatula.

[0046] [4] Next, the substrate 11 to which the liquid composition has been applied is dried to obtain the composition layer 12. The drying method is not particularly limited, but examples include leaving it at room temperature, using a blower to blow air, or using a heating device such as a dryer or oven for heat drying. However, drying is preferably carried out at a temperature of about 5°C to 100°C, which allows for relatively rapid drying while preventing deformation of the substrate 11 or denaturation of the water-soluble polymer or pH indicator in the liquid composition.

[0047] As described above, a pH testing tool 1 is obtained in which a composition layer 12 is provided on the surface of the substrate 11, that is, the composition is supported on the substrate 11. Furthermore, they may be provided in the following embodiments.

[0048] (1) A composition for testing the pH of a test solution, comprising a water-soluble polymer and a pH indicator, wherein the water-soluble polymer has an aqueous solution viscosity (4% by mass, 20°C) of 60 mPa·s or more and 10,000 mPa·s or less, as measured by a coaxial double-cylinder rotational viscometer as specified in JIS Z 8803:2011.

[0049] (2) The composition described in (1) above, wherein the pH indicator has a color change range that includes a pH of 5 or more and a pH of 7 or less.

[0050] (3) The composition according to (1) or (2) above, wherein the pH indicator is such that the hue difference between the hue when its aqueous solution is adjusted to pH 5 and the hue when it is adjusted to pH 7 is 54° or more and 180° or less on the Munsell color system's 20-color hue circle.

[0051] (4) A composition according to any one of (1) to (3) above, wherein the pH indicator comprises bromothymol blue and methyl red.

[0052] (5) The composition described in (4) above, wherein the mass ratio of bromothymol blue to methyl red is 0.1 or more and 10 or less.

[0053] (6) A composition according to any one of (1) to (5) above, wherein the water-soluble polymer comprises a vinyl alcohol-based polymer having a viscosity-average degree of polymerization of 1500 or more and 6000 or less, as measured by the method described in JIS K 6726:1994, and a degree of saponification of 65 mol% or more and 98 mol% or less.

[0054] (7) A composition according to any one of (1) to (6) above, wherein the mass ratio of the water-soluble polymer to the pH indicator is 3 or more and 12000 or less.

[0055] (8) A composition according to any one of (1) to (7) above, wherein the test solution includes a liquid of biological origin.

[0056] (9) A composition according to any one of (1) to (8) above, wherein the test solution includes urine.

[0057] (10) A pH testing device for testing the pH of a test solution, comprising a base material and a composition according to any one of (1) to (9) above, supported on the base material.

[0058] (11) pH testing device as described in (10) above, wherein the base material is a paper base material.

[0059] (12) pH testing device as described in (10) or (11) above, wherein the base material is in the form of particulate matter.

[0060] (13) A pH testing device as described in (11) or (12) above, wherein the pH testing device has a hue difference of 36° or more and 180° or less on the Munsell color system's 20-color hue circle between the hue when urine with pH 5 is applied as the test solution and the hue when urine with pH 7 is applied.

[0061] (14) A method for manufacturing a pH testing device for testing the pH of a test solution, comprising the steps of: preparing a base material, a water-soluble polymer having an aqueous solution viscosity (4% by mass, 20°C) of 60 mPa·s or more and 10,000 mPa·s or less as measured by a coaxial double-cylindrical rotational viscometer specified in JIS Z 8803:2011, and a pH indicator; and applying a liquid composition containing the water-soluble polymer and the pH indicator to the base material, and then drying it to obtain the pH testing device.

[0062] (15) A method for manufacturing a pH testing device as described in (14) above, wherein the liquid composition contains 1% by mass or more and 20% by mass or less of the water-soluble polymer, contains 0.001% by mass or more and 1% by mass or less of the pH indicator, and has a pH of 4 or more and 8 or less.

[0063] (16) A method for manufacturing a pH testing device as described in (14) or (15) above, wherein the pH indicator has a color change range of 5 to 7.

[0064] (17) A method for manufacturing a pH testing device according to any one of (14) to (16) above, wherein the pH indicator comprises bromothymol blue and methyl red. Of course, this is not always the case.

[0065] As described above, various embodiments relating to this disclosure have been explained, but these are presented as examples only and do not limit the scope of the invention in any way. The novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Such embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

[0066] For example, another layer may be provided between the base material 11 and the composition layer 12 of the pH testing device 1. Furthermore, the test may be conducted as a product in which the pH testing tool 1 is pre-installed in equipment or sanitary supplies for collecting the test fluid, such as pet litter, pet sheets, bedding materials for livestock sheds (sawdust, straw, etc.), human or pet diapers, or urine collection containers, or as a kit that combines these with the pH testing tool 1. This product or kit may include information such as the relationship between hue 21 and pH, or the relationship between the hue 21 of the test fluid and disease. This information may be presented on a physical medium such as paper, or on a web medium accessible via a QR code attached to the product or kit itself or its packaging. [Examples]

[0067] The contents of this disclosure will be further explained below with reference to examples. However, this disclosure is not limited to these examples.

[0068] 1.Measurement method (Measurement of viscosity-average degree of polymerization) The viscosity-average degree of polymerization of water-soluble polymers was measured in accordance with JIS K 6726:1994. Specifically, the water-soluble polymers were first saponified using sodium hydroxide to a degree of saponification of 99.5 mol% or higher. Then, the viscosity-average degree of polymerization P was determined (measured) using the intrinsic viscosity [η] (g / dL) measured at 30°C with an Ostwald viscometer using deionized water as the solvent, according to the following formula (1). log(P)=1.613×log([η]×104 / 8.29) ···(2) (Measurement of saponification degree) The degree of saponification of water-soluble polymers was calculated (measured) by titration in accordance with JIS K 6726:1994.

[0069] (Measurement of aqueous solution viscosity) The viscosity of aqueous solutions of water-soluble polymers was measured using a coaxial double-cylinder rotational viscometer with a constant-speed inner cylinder, for aqueous solutions of water-soluble polymers prepared at 4% by mass and 20°C, in accordance with JIS Z 8803:2011. (Measuring pH) The pH of aqueous solutions was measured at a temperature of 20°C in accordance with JIS Z 8802:2011.

[0070] (Hue determination) The color of pH indicators and other substances was determined visually by referring to the color wheel 2 shown in Figure 2.

[0071] 2. Preparation of liquid composition 2-1. Preparation of water-soluble polymers (Example 1) In a polymerization vessel equipped with a reflux condenser, dropping funnel, and stirrer, 100 parts by mass of vinyl acetate and 0.16 parts by mass of TAIC were charged as raw material monomers, 66.7 parts by mass of methanol as a solvent, and 0.003 parts by mass of di-n-propyl peroxydicarbonate (manufactured by Nippon Oil & Fats Co., Ltd., "Perloyl NPP") as an initiator. Polymerization was carried out below the boiling point for 8 hours while stirring under a nitrogen atmosphere. Polymerization was stopped when the conversion rate of vinyl acetate reached 56%, and unreacted vinyl acetate was removed from the polymerization system by a standard method. This yielded a methanol solution of a vinyl acetate polymer with a viscosity-average degree of polymerization of 3300.

[0072] A methanol solution of sodium hydroxide (calculated as 0.008 moles of sodium hydroxide relative to the structural units derived from vinyl acetate) was added to the methanol solution of the vinyl acetate polymer obtained above, and a saponification reaction was carried out at 45°C for 45 minutes. The resulting reaction solution was heated and dried to obtain a water-soluble polymer (vinyl alcohol polymer) according to Example 1, with a degree of saponification of 90 mol% and an aqueous solution viscosity (4% by mass, 20°C) of 120 mPa·s.

[0073] (Example 2) In a polymerization vessel equipped with a reflux condenser, dropping funnel, and stirrer, 100 parts by mass of vinyl acetate and 1.75 parts by mass of dodecyl vinyl ether were charged as raw material monomers, 19.8 parts by mass of methanol as a solvent, and 0.015 parts by mass of di-n-propyl peroxydicarbonate (manufactured by Nippon Oil & Fats Co., Ltd., "Perloyl NPP") as an initiator. Polymerization was carried out below the boiling point for 6 hours while stirring under a nitrogen atmosphere. Polymerization was stopped when the conversion rate of vinyl acetate reached 75%, and unreacted vinyl acetate was removed from the polymerization system by a standard method. This yielded a methanol solution of a vinyl acetate polymer with a viscosity-average degree of polymerization of 1700.

[0074] A methanol solution of sodium hydroxide (calculated as 0.008 moles of sodium hydroxide relative to the structural units derived from vinyl acetate) was added to the methanol solution of the vinyl acetate polymer obtained above, and a saponification reaction was carried out at 45°C for 45 minutes. The resulting reaction solution was heated and dried to obtain a water-soluble polymer (vinyl alcohol polymer) according to Example 2, with a degree of saponification of 88 mol% and an aqueous solution viscosity (4% by mass, 20°C) of 6000 mPa·s.

[0075] (Example 3, Comparative Example 2) A water-soluble polymer (vinyl alcohol-based polymer) with a degree of saponification of 88 mol% and an aqueous solution viscosity (4% by mass, 20°C) of 120 mPa·s was obtained in the same manner as in Example 1.

[0076] (Comparative Example 1) In a polymerization vessel equipped with a reflux condenser, dropping funnel, and stirrer, 100 parts by mass of vinyl acetate was charged as the raw material monomer, 66.7 parts by mass of methanol as the solvent, and 0.008 parts by mass of di-n-propyl peroxydicarbonate (manufactured by Nippon Oil & Fats Co., Ltd., "Perloyl NPP") as the initiator. Polymerization was carried out below the boiling point for 6 hours under a nitrogen atmosphere with stirring. Polymerization was stopped when the conversion rate of vinyl acetate reached 80%, and unreacted vinyl acetate was removed from the polymerization system by a standard method. This yielded a methanol solution of a vinyl acetate polymer with a viscosity-average degree of polymerization of 500.

[0077] A methanol solution of sodium hydroxide (calculated as 0.008 moles of sodium hydroxide relative to the structural units derived from vinyl acetate) was added to the methanol solution of the vinyl acetate polymer obtained above, and a saponification reaction was carried out at 45°C for 45 minutes. The resulting reaction solution was heated and dried to obtain a water-soluble polymer (vinyl alcohol-based polymer) according to Comparative Example 1, with a degree of saponification of 88 mol% and an aqueous solution viscosity (4% by mass, 20°C) of 10 mPa·s.

[0078] 2-2. Preparation of pH indicator (Examples 1-3, Comparative Examples 1, 3) A pH indicator was obtained by mixing 80 parts by mass of BTB and 20 parts by mass of MR. When the aqueous solution containing the pH indicator was adjusted to pH 5, the hue 21 was 10YR (see Figure 2), and when it was adjusted to pH 7, the hue 21 was 10GY, and the hue difference θ was 72°.

[0079] (Comparative Example 2) A pH indicator consisting solely of MR was obtained. When the aqueous solution containing the pH indicator was adjusted to pH 5, the hue 21 was 5YR (see Figure 2), and when it was adjusted to pH 7, the hue 21 was 5Y, with a hue difference θ of 36°.

[0080] 2-3. Preparation of liquid composition The obtained water-soluble polymer, pH indicator, and other components were dissolved in deionized water to obtain a liquid composition with a pH of 6. The components of the liquid composition are shown in Table 1 below, and the mixing ratios of each component are shown in Table 2 below.

[0081] [Table 1]

[0082] [Table 2]

[0083] 3. Preparation of testing equipment A sheet of white tissue paper was moistened with deionized water, folded and twisted, and dried at room temperature to obtain a roughly cylindrical paper substrate about 1 cm in height. The liquid composition was then applied to the obtained substrate to create a layer of 1 g / m² on the surface of the substrate. 2 The liquid composition was applied to the substrate. Subsequently, the substrate to which the liquid composition was applied was air-dried at room temperature for 24 hours to obtain the testing device.

[0084] 4. Evaluation A plastic cup was filled with a paper substrate (hereinafter also referred to as "uncoated substrate") that was not coated with the liquid composition, to a thickness of approximately 3 cm from the bottom, and 5 to 10 test tools were placed on top. Two such cups were prepared for each example and comparative example. By adding acetic acid and sodium hydroxide aqueous solution to pure water, test solutions with a pH of 5 to 8 were obtained. Approximately 5 ml of the pH 5 test solution was added to one cup, and approximately 5 ml of the pH 7 test solution was added to the other cup using a dropper, ensuring that the urine coated the entire surface of the test equipment in each cup.

[0085] 4-1. pH responsiveness The hue 21 of the testing instrument (see Figure 2) and the hue difference θ were visually determined immediately after the test solution was dropped onto the instrument, and the pH responsiveness was evaluated according to the following evaluation criteria. [Evaluation Criteria] A: Hue difference θ is between 60° and 180° (the difference in pH is very easy to see) B: Hue difference θ is between 30° and 60° (the difference in pH can be detected to some extent) C: Hue difference θ is less than 30° (difficult to distinguish pH differences)

[0086] 4-2. Colorfastness The contents of the cup were visually observed immediately after the test solution was dropped in, and the colorfastness was evaluated according to the following evaluation criteria. [Evaluation Criteria] A: The surrounding uncoated substrate remains white, and the leakage of the pH indicator cannot be visually confirmed (colorfast). B: Some of the pH indicator has leaked out, causing slight discoloration to the surrounding uncoated substrate (poor colorfastness). C: pH indicator leached out, causing significant discoloration of the surrounding uncoated substrate (no resistance to color fading).

[0087] 4-3. Color retention After dropping the test solution, the hue of the testing instrument was determined 30 minutes later, and the color retention was evaluated according to the following criteria based on a comparison with the hue immediately after dropping. [Evaluation Criteria] A: The color of the test instrument did not change at any pH level (color retention was observed). B: At any pH level, the hue of the test instrument changes, and the resulting hue difference θ is 10° or less (low color retention). C: At any pH level, the hue of the test instrument changes, and the resulting hue difference θ exceeds 10° (no color retention).

[0088] The evaluation results described above are summarized in Table 3 below.

[0089] [Table 3]

[0090] For reference, Figure 3 shows the results of preparing additional cups for Example 1 and Comparative Example 3 and adding test solutions with different pH levels. Figure 3 shows the state of the cups for Example 1 and Comparative Example 3 30 minutes after adding the test solutions with different pH levels. In Example 1 shown in the upper section, the test tool 1A developed color well in cups to which test solutions ranging from pH 5.5 to pH 7.0 were dropped, maintaining the hue of 5YR at pH 5.5, 5Y at pH 6.3, and 5GY at pH 7.0. Furthermore, the uncoated substrate 3A surrounding the test tool 1A showed no discoloration and remained white. In other words, the test tool 1A in Example 1 showed good results in all aspects: pH responsiveness, colorfastness, and color retention.

[0091] On the other hand, in Comparative Example 3 shown in the lower section, the color of the test tool 1B was mottled in all cups to which the test solution at pH 5.5 to pH 7.0 was dropped. Specifically, at pH 5.5, the test tool 1B showed a mottled color containing 5YR and 10YR; at pH 6.3, a mottled color containing 5Y and 10Y; and at pH 7.0, a mottled color containing 10Y and 5GY. In addition, in all cups, discoloration showing a 10YR hue was observed on the uncoated substrate 3B around the test tool 1B, suggesting leakage of the pH indicator. In other words, the test tool 1B in Comparative Example 3 lacked both colorfastness and color retention. Furthermore, as shown in Table 3, its pH responsiveness was also not good. [Explanation of Symbols]

[0092] 1: Inspection tools 11: Base material 12: Composition layer 2: Hue wheel 21: Hue θ: Hue difference 1A: Inspection tools 3A: Uncoated substrate 1B: Inspection tools 3B: Uncoated base material

Claims

1. A composition for testing the pH of a test solution, It contains a water-soluble polymer and a pH indicator. The water-soluble polymer has an aqueous solution viscosity (4% by mass, 20°C) of 60 mPa·s or more and 10,000 mPa·s or less, as measured by a coaxial double-cylinder rotational viscometer as specified in JIS Z 8803:2011. composition.

2. In the composition according to claim 1, The aforementioned pH indicator has a color change range that includes a pH of 5 to 7. composition.

3. In the composition according to claim 1, The aforementioned pH indicator has a hue difference of 54° to 180° on the Munsell color system's 20-color hue circle between the hue when its aqueous solution is adjusted to pH 5 and the hue when it is adjusted to pH 7. composition.

4. In the composition according to claim 1, The pH indicator comprises bromothymol blue and methyl red. composition.

5. In the composition according to claim 4, The mass ratio of bromothymol blue to methyl red is 0.1 or more and 10 or less. composition.

6. In the composition according to claim 1, The water-soluble polymer includes a vinyl alcohol-based polymer having a viscosity-average degree of polymerization of 1500 to 6000 and a degree of saponification of 65 mol% to 98 mol%, as measured by the method described in JIS K 6726:1994. composition.

7. In the composition according to claim 1, The mass ratio of the water-soluble polymer to the pH indicator is 3 or more and 12000 or less. composition.

8. In the composition according to claim 1, The aforementioned test fluid includes a fluid of biological origin. composition.

9. In the composition according to claim 1, The aforementioned test fluid includes urine. composition.

10. A pH testing device for examining the pH of a test solution, Substrate and The composition comprising the composition according to any one of claims 1 to 9, supported on the substrate, pH testing equipment.

11. In the pH testing device according to claim 10, The aforementioned substrate is a paper substrate. pH testing equipment.

12. In the pH testing device according to claim 10, The aforementioned substrate is in the form of parts. pH testing equipment.

13. In the pH testing device according to claim 11, The aforementioned pH testing device has a hue difference of 36° to 180° on the Munsell color system's 20-color hue circle between the hue when urine with pH 5 is applied and the hue when urine with pH 7 is applied. pH testing equipment.

14. A method for manufacturing a pH testing device for testing the pH of a test solution, The process involves preparing a base material, a water-soluble polymer whose aqueous solution viscosity (4% by mass, 20°C) measured by a coaxial double-cylinder rotational viscometer specified in JIS Z 8803:2011 is 60 mPa·s or more and 10,000 mPa·s or less, and a pH indicator. The process includes the steps of applying a liquid composition containing the water-soluble polymer and the pH indicator to the substrate, and then drying it to obtain the pH testing device. A method for manufacturing pH testing equipment.

15. In the method for manufacturing a pH testing device according to claim 14, The liquid composition has a water-soluble polymer content of 1% by mass or more and 20% by mass or less, a pH indicator content of 0.001% by mass or more and 1% by mass or less, and a pH of 4 or more and 8 or less. A method for manufacturing pH testing equipment.

16. In the method for manufacturing a pH testing device according to claim 14, The pH indicator has a color change range of 5 to 7. A method for manufacturing pH testing equipment.

17. In the method for manufacturing a pH testing device according to any one of claims 14 to 16, The pH indicator comprises bromothymol blue and methyl red. A method for manufacturing pH testing equipment.

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