JP7191360B2 - Indicator and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an indicator containing a coloring component that develops color by detecting a target component, and a manufacturing method thereof.

The indicator is used, for example, to check whether or not a liquid to be tested contains a target component (eg, H ⁺ , OH ⁻ , oxidizing agent, etc.) at a predetermined concentration or higher. Typical indicators include oxidant indicators (eg, oxidant test strips). For example, an oxidizing agent is used as a disinfectant in a disinfectant solution for disinfecting instruments such as medical instruments. Indicators are used to determine whether the disinfectant solution contains an effective concentration of disinfectant. Oxidant indicators include, for example, those that utilize the iodine-starch reaction.

The oxidizing agent indicator includes a strip-shaped base sheet and a porous layer (paper, non-woven fabric, etc.) formed on the surface of the base sheet. The porous layer contains a coloring component (eg, potassium iodide and starch) that detects and colors the target component. The porous layer is formed at one end in the length direction of the base sheet. In the oxidizing agent indicator, when the porous layer portion is immersed in the liquid to be tested, potassium iodide is oxidized by the oxidizing agent to generate iodine molecules, and the iodine molecules react with starch to develop a color. By the degree of discoloration at this time, it can be confirmed whether or not the oxidizing agent is contained at a predetermined concentration or higher.

A strip-shaped indicator (test paper, etc.) is manufactured by forming a porous layer on the surface at the end of the base sheet, impregnating the porous layer with a drug-containing solution, and drying (for example, Patent document 1).

JP-A-2006-275716 (paragraph [0065])

However, when a strip-shaped indicator is manufactured and such an indicator is used to confirm the concentration of the target component in the liquid, the test accuracy may be degraded.

One aspect of the present invention comprises a strip-shaped base sheet and a porous layer formed on one side of the base sheet,
The porous layer is arranged at one end in the length direction of the base sheet, and has a first edge on the one end side, a second edge on the side opposite to the first edge, and the second edge on the side opposite to the first edge. a center portion located between one edge portion and the second edge portion;
The porous layer includes a first coloring component that detects a target component and reacts with each other to develop a color, and a second coloring component having a higher molecular weight than the first coloring component,
A ratio R1 (=C12/C1c) of the concentration C12 of the first coloration component at the second edge portion to the concentration C1c of the first coloration component at the center portion is 2.2 or less. .

Another aspect of the present invention comprises a strip-shaped base sheet and a porous layer formed on one surface of the base sheet,
The porous layer is arranged at one end in the length direction of the base sheet, and has a first edge on the one end side, a second edge on the side opposite to the first edge, and the second edge on the side opposite to the first edge. a center portion located between one edge portion and the second edge portion;
The porous layer includes a first coloring component that detects a target component and reacts with each other to develop a color, and a second coloring component having a higher molecular weight than the first coloring component,
The base sheet relates to the indicator, wherein the base sheet has a half-cut mark immediately below the side end surface of the porous layer on the second edge portion side.

According to still another aspect of the present invention, a preparation step of preparing a base sheet and a porous layer formed on one surface of the base sheet;
a diffusion step of diffusing a first coloring component that detects a target component and reacts with each other to develop a color and a second coloring component having a molecular weight larger than that of the first coloring component in the porous layer;
The present invention relates to a method for producing an indicator, comprising a dividing step of dividing the porous layer into an end region where the concentration of the first color component is relatively high and the remainder by half-cutting.

It is possible to improve the inspection accuracy of the indicator containing the color component.

1 is a schematic plan view of a strip-shaped indicator according to one embodiment of the present invention; FIG. FIG. 4 is a schematic plan view of an indicator according to another embodiment of the invention; FIG. 5 is a schematic plan view of an indicator according to still another embodiment of the invention; It is process drawing for demonstrating the manufacturing method of the indicator which concerns on embodiment of this invention. It is a process drawing for demonstrating the procedure in the case of manufacturing an indicator industrially.

[indicator]
An indicator according to one embodiment of the present invention includes a strip-shaped (that is, strip-shaped) base sheet and a porous layer formed on one surface of the base sheet. The porous layer is arranged at one end in the length direction of the base sheet, and includes a first edge on the one end side, a second edge on the side opposite to the first edge, the first edge and the second edge. and a central portion located between the two edge portions. The porous layer contains a first coloration component and a second coloration component that detect a target component and react with each other to develop a color. A ratio R1 (=C12/C1c) of the density C12 of the first color component at the second edge portion to the density C1c of the first color component at the central portion is 2.2 or less.

In an indicator comprising a strip-shaped base sheet and a porous layer formed on the surface thereof, the porous layer generally contains a coloring component that detects and colors a target component. It has been found that the following method is efficient for industrial production of such an indicator.

First, as shown in FIG. 5, a strip-shaped porous layer P0 is provided in the central portion in the width direction of a base sheet S0 having a large size (more specifically, for a plurality of indicators), and contains a coloring component. The solution is applied (eg, impregnated) to the porous layer P0 and dried (step (a)). Next, as indicated by the dashed line, the base sheet S0 is divided into two along with the porous layer P0 in the width direction and finely cut in the length direction to obtain a strip-like (that is, strip-like) indicator ( step (b)). In the strip-shaped indicator, a porous layer P is arranged on one surface of one end of a strip-shaped base sheet S. As shown in FIG.

However, in the method of applying the solution after forming the porous layer P0 by using the base sheet S0 for a plurality of indicators, the coloring component is applied to the entire porous layer P0 at once in the step (a). difficult to give. Therefore, usually, the solution is applied to a partial region of the porous layer P0 (for example, the central portion in the width direction of the porous layer P0) to diffuse the coloring component throughout the porous layer P0. The applied solution diffuses from the applied portion to the periphery in the surface direction of the porous layer. In such a method, the timing at which the coloring component is diffused varies depending on the position in the porous layer P0, so that the distribution of the coloring component tends to vary. Application of the solution is performed, for example, by dropping or coating. At this time, for example, the solution may be continuously applied to the central portion of the porous layer P0 in the width direction from one end portion to the other end portion in the length direction of the porous layer P0. The solution may be applied to the central portion in the width direction of the porous layer P0 from a plurality of ejection ports arranged open. In these cases, the distribution of the color components is further varied.

In step (a), in order to suppress the formation of regions in the porous layer P0 in which no color component exists, it is necessary to sufficiently diffuse the color component within the porous layer P0. However, while the coloring component is being diffused throughout the porous layer P0, the coloring component may accumulate at the edges of the porous layer P0, resulting in an excessively high concentration of the coloring component. In the indicator obtained by cutting the porous layer P0 in such a state together with the base sheet S0 in step (b), the porous layer P is arranged at one end in the length direction of the base sheet S. becomes. Then, at the edge portion of the porous layer P on the other end portion side in the length direction of the base sheet S, the concentration of the coloring component becomes excessively high. When the indicator in such a state is used to inspect the concentration of the target component in the liquid to be tested, an excessive color reaction occurs at the edge portion where the concentration of the color component is high, and the inspection accuracy decreases. In particular, when the porous layer contains a plurality of color-developing components involved in the color reaction, the diffusibility in the porous layer differs if the molecular weights of these color-developing components differ. Therefore, while the coloring component with low diffusibility is uniformly diffused in the porous layer P0, the coloring component with higher diffusibility accumulates at the edge of the porous layer P0, and the concentration tends to be excessively high. , the inspection level tends to decrease. In addition, depending on the type of coloring component, the color of the edge portion of the porous layer having a high concentration of the coloring component may be darker than the other regions before the test. This may lead to deterioration of inspection accuracy.

1 is a schematic plan view of an indicator according to one embodiment of the present invention; FIG.
The indicator includes a strip-shaped base sheet S and a porous layer P formed on one surface of the base sheet S. As shown in FIG. The porous layer P is arranged at one end of the base sheet S in the longitudinal direction. The porous layer P includes a first edge portion E1 on one end side of the base sheet S, a second edge portion E2 on the side opposite to the first edge portion E1, the first edge portion E1 and the second edge portion E2. and a central portion C located between.

In this embodiment, the ratio R1 (=C12/C1c) of the concentration C12 of the first color component at the second edge portion E2 of the porous layer P of the indicator to the concentration C1c of the first color component at the central portion C is 2.2 or less. That is, excessive increase in the concentration of the first color component at the second edge portion E2 of the porous layer P is suppressed. Therefore, the second edge portion E2 is prevented from being darkly colored by the first coloring component, and excessive occurrence of a coloring reaction at the second edge portion E2 is also prevented. Therefore, it is possible to improve the inspection accuracy of the indicator.

In addition, in the strip-shaped indicator, when the porous layer is arranged at one end in the length direction of the base sheet, the end of the porous layer on the one end side of the base sheet (for example, the width of 2 mm from the end) ) is referred to as a first edge portion, and an end portion of the porous layer opposite to the first edge portion (for example, a portion having a width of 2 mm from the end) is referred to as a second edge portion. The center portion refers to the portion of the porous layer located in the center in the direction along the length direction of the base sheet. The concentration of each component in the central portion may be obtained, for example, for a 2 mm wide band-shaped portion located in the center of the porous layer in the direction along the length direction of the base sheet. It may be a value obtained by averaging two adjacent belt-like portions with a width of 2 mm sandwiching the center line in the direction along the length direction of the sheet.
Hereinafter, the indicator according to the present embodiment will be described in more detail with appropriate reference to the drawings.

(Porous layer)
In the indicator, the porous layer is formed on one side of a strip-shaped base sheet. The porous layer has a length shorter than that of the base sheet and is arranged at one end in the length direction of the base sheet. The porous layer contains a first coloring component and a second coloring component that detect a target component and react with each other to develop a color. In such an indicator, by bringing a liquid containing a target component into contact with the porous layer of the indicator, a color reaction involving the first coloration component and the second coloration component occurs, and the target component in the liquid Concentration can be checked.

The porous layer may be formed on one side of the base sheet, but may be formed on both sides of the base sheet if necessary. In addition, as in the example of FIG. 1, it may be formed not only at one end in the length direction of the base sheet but also at both ends. At this time, on one surface of the base sheet, the porous layer may be provided on both ends, and on one surface of the base sheet, the porous layer is provided on one end and the other surface , a porous layer may be provided at the other end.

The porous layer may be, for example, a porous film, but preferably includes a fiber assembly from the viewpoint of facilitating impregnation with a solution containing a coloring component or a liquid to be tested. Also, a laminate of a porous film and a fiber assembly may be used as the porous layer. Examples of fiber aggregates include paper (including filter paper), nonwoven fabric, woven fabric, and knitted fabric. Among these, paper and non-woven fabric are preferable from the viewpoint of high impregnation with liquid.

The material for the porous layer may be selected depending on the application, and examples thereof include cellulose or derivatives thereof (cellulose ester, cellulose ether, etc.), resins (polyolefin resin, polyester resin, polyamide resin, etc.). The porous layer may contain one or more of these materials.

The porous layer (specifically, the fiber aggregate) contains a first coloration component and a second coloration component having a larger molecular weight than the first coloration component. More specifically, the first coloration component and the second coloration component are impregnated or carried in the porous layer (specifically, the fiber assembly). The first coloration component and the second coloration component are respectively diffused (or distributed in a dispersed state) in the porous layer (specifically, the fiber assembly). As the first coloration component and the second coloration component, for example, various substances can be used according to the use of the indicator.

Examples of the first color-developing component include a component that develops color by reacting with a second color-developing component described below in the presence of the target component. Examples of the first color component include redox indicators, adsorption indicators, and TLC (thin layer chromatography) color indicators. As the first coloring component, two or more of these may be used as necessary, but the concentration of the first coloring component in each portion included in the porous layer, such as the second edge portion and the central portion, is , is calculated by paying attention to one kind of first coloration component.

As the second coloring component, for example, one that reacts with the first coloring component to develop color in the presence of the target component can be used. Since the second coloration component has a higher molecular weight than the first coloration component, the diffusivity when impregnating the porous layer with the second coloration component is lower than that of the first coloration component. When the second color component is a polymer, the average molecular weight (for example, weight average molecular weight) of the second color component should be larger than the molecular weight of the first color component.

The second coloration component may be selected according to the type of the first coloration component and/or the target component. For example, when the target component is an oxidizing agent, an iodide that produces iodine in the presence of the oxidizing agent may be used as the first coloring component, and starch may be used as the second coloring component. In this case, starch and iodine produced by oxidizing iodide in the presence of an oxidizing agent undergo an iodine-starch reaction to cause color development, and the presence of the oxidizing agent can be detected. Preferred iodides are sodium iodide and potassium iodide. Among them, potassium iodide is preferable from the viewpoint of easily generating iodine by the action of an oxidizing agent.

In this specification, the first coloration component is a component A (such as iodine) that actually reacts with the second coloration component to develop a color, and the component A can be generated in the presence of the target component. component A precursor (such as iodide). That is, the concentration of the first coloration component in each portion such as the second edge portion and the central portion may be calculated by focusing on either the component A or its precursor.

The porous layer can contain additives depending on the application, if necessary. For example, the porous layer may contain an additive for facilitating confirmation of the color reaction between the first coloring component and the second coloring component. For example, when iodide is used as the first color component and starch is used as the second color component, the porous layer preferably further contains a reducing agent. The reducing agent has the function of reducing iodine produced by oxidation of iodide by the oxidizing agent as the target component, and can suppress excessive color reaction, so that the inspection accuracy can be further improved. . As the reducing agent, iron (II) ions, tin (II) ions, hydrides, etc. may be used, but from the viewpoint of easily reducing iodine, thiosulfates, sulfites, hyposulfites, etc. may be used. preferable. Preferred thiosulfates, sulfites, and hyposulfites are alkali metal salts such as sodium salts and potassium salts, respectively. The reducing agents may be used singly or in combination of two or more.

In the present embodiment, the ratio R1 (=C12/C1c) of the concentration C12 of the first coloration component at the second edge portion to the concentration C1c of the first coloration component at the center portion may be 2.2 or less. is important. As a result, it is possible to suppress the occurrence of excessive color reaction in the second edge portion and its vicinity, so that the inspection accuracy of the indicator can be improved. From the viewpoint of reducing variations in color reaction in the porous layer, the ratio R1 is preferably 2 or less, more preferably 1.7 or less. When the porous layer contains a reducing agent, the ratio R1 is more preferably 1.3 or less or 1.2 or less, and may be 1.1 or less.

In the indicator, the first coloration component is supported on the porous layer by applying (for example, impregnating) a solution containing the first coloration component to the porous layer and drying it. Therefore, the porous layer may have a gradient in the distribution of the first color component. For example, in the porous layer, the concentration of the first color component may increase from the first edge toward the second edge. However, in the indicator having such a slope of the density distribution, the density of the first coloration component tends to be excessively high at the second edge portion compared to the central portion and the first edge portion. In the present embodiment, even when having such a concentration distribution, by suppressing the concentration ratio R1 of the first color component to the above range, it is possible to ensure high inspection accuracy of the indicator. The density of the first color component may increase continuously from the first edge toward the second edge, or may increase stepwise.

The density ratio R1 of the first color component can be obtained as follows. First, the first color component extracted from each part is identified using nuclear magnetic resonance spectrum, mass spectrum, or the like. Next, the first coloring component extracted from each part is dissolved in a predetermined amount of solvent, and the absorbance at the wavelength characteristic of the first coloring component is measured. Then, by comparing with the absorbance of a sample of a solution containing the first coloring component with a known concentration, the content (g) of the first coloring component in each of the second edge portion and the central portion is obtained, and the second edge The ratio of the content (g) of the first coloration component in the part to the content (g) of the first coloration component in the central part can be calculated, and this content ratio can be used as the concentration ratio R1. . The first color component can be extracted by cutting out the second edge portion and the central portion from the indicator and using a solvent (such as water and/or an organic solvent) from each portion.

When actually obtaining the concentration (% by mass) of the first coloration component in each part, the ratio (% by mass) of the content (g) of the first coloration component to the mass (g) of the porous layer ) can be calculated and used as the actual concentration (% by mass) of the first color component in each part. The mass of the porous layer in each part may be obtained by measuring the dry mass of the porous layer after peeling the porous layer from the base sheet in each part. It may be obtained by measuring the total dry mass of , and subtracting the weight of the base sheet weighed after cleanly peeling the porous layer from the base sheet.

Further, instead of actually obtaining the content and concentration of the first coloring component in each part, the absorbance of the first coloring component extracted from the second edge part relative to the absorbance of the first coloring component extracted from the central part A ratio may be obtained and this absorbance ratio may be used as the concentration ratio R1. In this case, by concentrating or diluting the obtained liquid so that the mass of the liquid obtained by extracting the first color component from each part becomes the same, the correction accompanying the concentration variation in each liquid becomes unnecessary. Become.

When the absorbance of the first color component itself contained in the indicator is small and it is difficult to calculate the concentration ratio, a component that causes coloration (for example, an oxidizing agent or a reducing agent) is added to the extracted first color component. Then, the density ratio R1 may be obtained in a colored state. In this case, the concentration ratio R1 may be obtained from the absorbance ratio in consideration of the molar ratio relationship between the coloring component and the first coloring component from the reaction formula of the first component and the coloring component.

In addition, when it is difficult to determine the concentration ratio R1 from the absorbance, using high performance liquid chromatography or gas chromatography, from the calibration curve obtained based on the sample of the solution containing the first color component with a known concentration, R1 may be calculated by obtaining the concentration of the first color component in each part.

The gradient of the density of the first color component can be obtained according to the density ratio R1. For example, the densities of the first color component at the first edge portion, the second edge portion, and the central portion may be obtained in the same manner as when obtaining the density ratio R1. Further, it is easy to measure the absorbance of each part in the same manner as in the case of the concentration ratio R1, and obtain the slope of the absorbance as the slope of the concentration. Further, when obtaining the slope of the absorbance, the absorbance in a state of coloring by adding a component for coloration to the first color component may be used as in the case of the concentration ratio R1.

The ratio R2 (=C22/C2c) of the concentration C22 of the second color component at the second edge portion to the concentration C2c of the second color component at the central portion is the same as the concentration ratio R1 of the first color component. It may be larger than R1, but preferably satisfies the relationship of R1>R2. Since the second coloration component has a higher molecular weight than the first coloration component, it is difficult to diffuse into the porous layer compared to the first coloration component, and the second coloration component diffuses throughout the porous layer. During this period, the density of the first coloration component may become high at the second edge portion and its vicinity. In this case, R1>R2 is likely to be established, and the color reaction tends to be excessive. For example, when using iodide as the first color component and starch as the second color component, the molecular weight of iodide is smaller than that of starch, and the diffusion rate is high. The concentration of iodide in the vicinity tends to be high. Even in such a case, according to the present embodiment, by suppressing the concentration ratio R1 within the above range, it becomes easier to ensure high inspection accuracy of the indicator. In other words, the indicator according to the present embodiment is particularly suitable when using the first coloration component and the second coloration component having a higher molecular weight (or a lower diffusion rate) than the first coloration component.
The concentration ratio R2 of the second coloration component is obtained by extracting the second coloration component from each part, identifying the second coloration component, and determining the content of the second coloration component in each part, in the same manner as in the case of R1. It can be determined from a ratio, a concentration ratio, an absorbance ratio, or the like.

When the porous layer contains an additive such as a reducing agent for facilitating confirmation of the color reaction, the additive (reducing agent etc.) to the concentration Crc is preferably less than 1.5, more preferably 1.2 or less or 1.1 or less. When the concentration ratio R4 of the additive is in such a range, it is easy to adjust the degree of coloration of the coloration reaction, and it becomes easy to further improve the inspection accuracy.
The additive concentration ratio R4 can be obtained by extracting the additive from each part, identifying the additive, and determining the content ratio, the concentration ratio, or the absorbance ratio of the additive in each part, in the same manner as in the case of R1. can be done.

Each of the second color-developing component and the additive (reducing agent, etc.) may also have a slanted distribution state in the porous layer as in the case of the first color-developing component. For example, in the porous layer, the concentration of the second color component and/or additive may increase from the first edge toward the second edge. When the diffusion rate of the second coloring component in the porous layer is small, the distribution of the second coloring component is lower than the gradient of the distribution of the first coloring component. slope becomes gentler. Regarding the gradient of the concentration of each component of the second coloring component and the additive in the porous layer, the state of the gradient of the absorbance can be used as an index in the same manner as in the case of the first coloring component.

The length of the porous layer may be determined according to the usage and size of the indicator. The length of the porous layer is, for example, 4 mm or more and 70 mm or less, preferably 5 mm or more and 10 mm or less.
The length of the porous layer is the length of the porous layer in the direction along the length of the strip indicator.

The thickness of the porous layer may be determined according to the material of the porous layer, the use of the indicator, and the like. The thickness of the porous layer is preferably, for example, 100 μm or more and 300 μm or less.

The indicator may further comprise a strip positioned adjacent to the porous layer. FIG. 2 is a schematic plan view of an indicator with strips. The band-shaped portion B is arranged adjacent to the second edge portion E2 of the porous layer P on one surface of the base sheet S. As shown in FIG. The band-shaped portion B contains the first coloration component and the second coloration component, and is removable from the base sheet S. Such a band-shaped portion B originally constitutes a part of the porous layer P, and is separated or divided from the porous layer P by cutting the outside of the second edge portion E2 of the porous layer P. formed by Therefore, the band-shaped portion B is made of the same material as the porous layer P. As shown in FIG.

Since the band-shaped portion B is originally in a continuous state with the porous layer P, the concentration of the first color component in the band-shaped portion B is the second edge portion E2, the central portion C, and the first It is higher than the density of the first coloration component at the edge portion E1. Therefore, the ratio R1 and the ratio R3 (=C13/C1c) of the concentration C13 of the first color component in the belt-shaped portion B to the concentration C1c of the first color component in the central portion C satisfy R3>R1. . Similarly, when the porous layer P contains additives such as a second color component and a reducing agent, the concentrations of these components in the belt-shaped portion B are It is higher than the density of each component in C and the second edge portion E2.
The concentration ratio R3 of the first coloration component is obtained by extracting the first coloration component from the belt-like portion and the central portion, identifying the first coloration component, and determining the first coloration component in each portion, in accordance with the case of R1. It can be determined from the content ratio, concentration ratio, absorbance ratio, or the like of the components.

The band B can be removed before the indicator is cut into strips, but if it is not removed and the strip is cut, the strip remains on the indicator as shown in FIG. From the viewpoint of ensuring higher inspection accuracy, it is preferable to remove the band-shaped portion B at an appropriate stage before subjecting the indicator to the test.

The width of the belt-shaped portion B is not particularly limited, but is, for example, 1 mm or more and 5 mm or less, preferably 1 mm or more and 4 mm or less, and 1 mm or more and 3 mm or less (especially 1 mm or more and 2 mm or less). When the band-shaped portion B has such a width, the concentration gradient of the first color component in the porous layer P can be easily reduced, so that the inspection accuracy of the indicator can be further improved.
The width of the band-shaped portion B is the length of the band-shaped portion B in the direction along the length direction of the strip-shaped indicator.

(base material sheet)
The base sheet should be able to hold the porous layer, but it preferably has an appropriate strength from the viewpoint of ensuring the handleability of the indicator. The material of the base sheet may be selected according to the use of the indicator. Examples of base sheets include films and fiber aggregates. The film may be a monolayer film or a multilayer film. Moreover, paper, a nonwoven fabric, a woven fabric, a knitted fabric, etc. are mentioned as a fiber assembly. A laminate of a film and a fiber assembly may be used as the base sheet.

Materials for the base sheet include, for example, cellulose or derivatives thereof (cellulose ester, cellulose ether, etc.), resins (polyolefin resin, polyester resin, polyamide resin, etc.). Examples of polyolefin resins include polyethylene and polypropylene. Examples of polyester resins include polyethylene terephthalate (PET) and polybutylene terephthalate. Polyamide resins include, for example, polyamide 6, polyamide 66, polyamide MXD, and the like. The base sheet may contain one or more of these materials.

The base sheet may be strip-shaped, and the width W3 and length L3 of the base sheet may be selected according to the use of the indicator. The width W3 of the base sheet is preferably, for example, 4 mm or more and 30 mm or less. The length L3 of the base sheet is preferably, for example, 40 mm or more and 100 mm or less.
The thickness of the base sheet is not particularly limited, but is, for example, 100 μm or more and 300 μm or less.

The base sheet may have half-cut marks. FIG. 3 is a schematic plan view of an indicator having half-cut marks. The indicator in FIG. 3 is the same as the indicator in FIG. 1 except that the base sheet S has half-cut marks. As shown in FIG. 3, the half-cut mark H is formed in the base sheet S directly below the side end surface of the porous layer P on the second edge portion E2 side.

The half-cut mark H is formed, for example, when the belt-like portion is sectioned or divided from the porous layer. The strip is separated from the porous layer P by cutting the outer edge of the second edge of the porous layer P. As shown in FIG. At this time, the base sheet S is not cut (that is, the porous layer is cut by half-cutting), but usually a trace (that is, a half-cut trace H) remains on the surface of the base sheet S. .

When the indicator is immersed in the liquid to be tested and pulled up, or when the liquid is dropped onto the porous layer portion of the indicator, excess liquid that cannot be completely absorbed by the porous layer is the second edge of the porous layer P. On the base sheet S outside the portion E2 (that is, in the cross section in the thickness direction in the length direction of the indicator, the stepped portion formed by the height difference between the surface of the porous layer P and the surface of the base sheet S) Accumulation may affect inspection accuracy. In the indicator having the half-cut mark H, even if excess liquid is supplied to the porous layer P, the liquid can easily flow along the half-cut mark H (that is, the liquid is easily drained), so that the liquid does not flow into the stepped portion. Accumulation is suppressed. Therefore, it becomes easier to ensure high inspection accuracy.

The half-cut marks H may be intermittently formed along the width direction of the base sheet S (for example, in the form of broken lines). From the viewpoint of ensuring higher liquid drainability, the half-cut mark H is continuous (for example, linear (especially linear)) from one end to the other end in the width direction of the base sheet S. It is preferably formed in

(Target component)
Since the indicator according to the present embodiment ensures excellent inspection accuracy, the concentrations of various target components involved in the color reaction of the first color component are inspected according to the type of the first color component. be able to. For example, when the first color component is iodide and the second color component is starch, the indicator indicates that the target component is an oxidizing agent (for example, hydrogen peroxide, peroxide such as peracetic acid, etc.). ) can be tested.

(Manufacturing method of indicator)
The method for producing an indicator according to the present embodiment includes a preparation step (i) of preparing a base sheet and a porous layer formed on one surface of the base sheet, and detecting a target component in the porous layer. a diffusion step (ii) of diffusing the first coloring component that reacts with each other to develop a color and the second coloring component having a molecular weight larger than that of the first coloring component; and the first coloring in the porous layer. A division step (iii) of half-cutting the end region having a relatively high component concentration and the remainder. Since a base sheet for a plurality of indicators is usually used in the preparation step (i), a strip-shaped indicator (more specifically, a strip-shaped indicator having a width W3 and a length L3) is cut out. Step (iv) is performed.

FIG. 4 is a process chart for explaining an example of the method of manufacturing the indicator according to this embodiment.
In the preparation step (i), a base sheet S0 having a large size is used. The base sheet S0 has a width W1 sufficiently larger than the length L3 of the strip-like indicator (for example, twice or more than L3) and a length sufficiently larger than the width W3 (for example, ten times or more than W3). has a height L1.

A strip-shaped porous layer P0 is attached along the length L1 direction to regions other than both ends in the width W1 direction of the base sheet S0. The strip-shaped porous layer P0 has a width W2 sufficiently smaller than the width W1 and a length L2. The strip-shaped porous layer P0 is attached, for example, to the central portion of the base sheet S0 in the width W1 direction.

In the preparatory step (i), the strip-shaped porous layer P0 may be attached to a predetermined position of the large-sized base sheet S0. An adhesive, a double-sided tape, or the like may be used for attachment, or heat welding, laser welding, or the like may be used.

Then, the step (ii) of diffusing the first coloration component and the second coloration component (additives, if necessary) into the porous layer P0 is performed. In the diffusion step (ii), the first coloration component and the second coloration component are applied to the porous layer P0 and diffused into the porous layer P0. As described above, when a coloring component is applied to a part of the porous layer P0 (for example, the central portion in the width direction of the strip-shaped porous layer P0) and diffused into the porous layer, Distribution of color components tends to vary. For example, when the coloring component is applied to the porous layer P0 by dripping, the coloring component is usually applied to a part of the porous layer P0 and diffused. When using a plurality of color components, the distribution of each color component tends to vary more. Even when the distribution of the color components tends to vary in this way, according to the present embodiment, by performing the classification step (iii), it is possible to provide an indicator with improved inspection accuracy.

In the diffusion step (ii), when the first coloration component is diffused into the porous layer P0, a solution containing the first coloration component is added, for example, , is supplied or applied to at least the central portion in the width direction of the strip-shaped porous layer P0. The first color component is gradually diffused to spread throughout the porous layer. Therefore, the concentration of the first color component at the edge of the strip-shaped porous layer P tends to be excessively high.

In the diffusion step (ii), the coloring component and/or additive is applied to the porous layer P0, for example, in the form of a solution. The application of color components and additives may be performed by impregnating the porous layer P0 with each component, but rather than immersion, the liquid may be applied directly to the porous layer P0 by, for example, dripping, spraying, or coating. It is preferable to use any method that is available. When the porous layer is impregnated with the coloring component by immersing the porous layer in a solution containing the coloring component, the density and thickness of the porous layer and the amount of solution retained due to surface tension vary. This is because the amount of the component supported on the porous layer tends to vary. On the other hand, since the amount of solution applied to the porous layer can be easily controlled by using dripping or the like, the amount of coloring component per unit area in the porous layer can be controlled at a constant level compared to the case of using immersion. easy to do Therefore, the quality of the indicator can be stabilized. However, as described above, when the coloring component is applied (or impregnated) to the porous layer by dripping or the like, the coloring component is applied to a part of the porous layer. It is difficult to control the distribution of the color component in the layer. According to the present embodiment, even if it is difficult to control the distribution of the color component, the classification step (iii) can improve the inspection accuracy of the indicator.

The component applied to the porous layer P0 diffuses into the porous layer P0. After applying the solution to the porous layer P0, the coloring component and/or the additive are carried on the porous layer P0 by drying. The first coloration component and the second coloration component may be applied to the porous layer P0 simultaneously or individually. The additive may be applied to the porous layer P0 simultaneously with at least one of the coloring components, or may be applied separately from the coloring component. For example, a solution containing the first coloration component and the second coloration component may be applied to the porous layer P0, and the solution containing the first coloration component and the solution containing the second coloration component are respectively It may be applied to the porous layer P0. In the latter case, each solution may be applied to the porous layer P0 simultaneously or separately (for example, one solution may be applied and then the other solution may be applied). When an additive is used, it may be added to the solution of the coloring component, or the additive may be applied to the porous layer P0 separately from the solution of the coloring component. When using a plurality of solutions each containing a color component, the additive may be added to some or all of the solutions.

More specifically, in the diffusion step (ii), the porous layer P0 is impregnated with a solution containing the first color component and dried to impregnate or impregnate the porous layer P0 with the first color component. can be carried. The second coloring component may be impregnated or carried in the porous layer P0 in the diffusion step (ii) in the same manner as the first coloring component. When an additive is used, it may be impregnated or carried in the porous layer P0 in the diffusion step (ii), as in the case of the first color component. The second coloration component and/or additive may be mixed with the solution containing the first coloration component, and the second coloration component and/or additive may be added separately from the solution containing the first coloration component. A solution containing it may be prepared and impregnated into the porous layer P0.

In the division step (iii), the end portion of the strip-shaped porous layer P0 where the concentration of the first colored portion is excessively high (that is, the portion outside the second edge portion E2 of the porous layer P in the strip-shaped indicator) (end region)) is cut along the cut position (half-cut position) h indicated by the dashed line to form the band-shaped portion B described above. The edge regions may be removed from the base sheet. By removing the end region, the concentration ratio R1 of the first color component in the porous layer P of the indicator can be adjusted within the above range.

The cutting of the end region (band-shaped portion B) can be performed by half-cutting, which cuts the porous layer P portion without cutting the base sheet S. As shown in FIG. At this time, a half-cut mark H may remain on the surface of the base sheet S. The half-cut mark H can provide an indicator that can ensure high inspection accuracy. The band-shaped portion B after the half-cut can be removed when the indicator is cut out, and the indicator as shown in FIG. 1 or the indicator with the half-cut mark H shown in FIG. 3 can be obtained. Further, the band-shaped portion B may be left on the indicator after being cut out. In this case, an indicator as shown in FIG. 2 is obtained.

The step (iv) of cutting out the indicator may be performed after the diffusion step (ii), but is preferably performed after the segmentation step (iii) and/or in parallel with the segmentation step (iii). Cutting of the edge regions can be easily performed. In the indicator cutting step (iv), a strip-shaped indicator having a width W3 and a length L3 is cut. In the step (iv) of cutting out the indicator, for example, the base sheet is divided into two parts in the width W1 direction along with the porous layer so as to cross the central part of the band-shaped porous layer, and into a plurality of parts in the length L1 direction. Just do it. For example, as in the case of FIG. 5, as shown by the dashed line in FIG. 4, the base sheet S0 is divided into two parts in the width W1 direction along with the porous layer P0 so as to cross the central portion of the band-like porous layer P0. , and finely cut in the length L1 direction to obtain a strip-like indicator. The cutting in the length L1 direction is preferably performed after the dividing step (iii) from the viewpoint of facilitating the cutting in the dividing step (iii). However, the halving in the width W1 direction may also be performed after the diffusion step (ii) and before the division step (iii), in parallel with the division step (iii) (e.g. (in parallel with the cutting of the edge regions).

[Example]
EXAMPLES The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

<Example 1 and Comparative Example 1>
(Preparation of indicator)
An aqueous solution a containing 0.23% by mass of potassium iodide as the first color component and an aqueous solution b containing 3.53% by mass of starch as the second color component were prepared.
A band-shaped filter paper (No. 1 filter paper manufactured by ADVANTEC, length 150 mm × width 16 mm) is placed in the central part of the width direction of a PET film (length 150 mm × width 100 mm × thickness 200 μm), and the length of the PET film and the filter paper is Aligned and attached with double-sided tape. The aqueous solution a and the aqueous solution b were each dropped onto the filter paper (specifically, the central portion in the width direction of the filter paper) to distribute the solutions over the entire filter paper. Then, it was dried in a constant temperature bath at 80°C for 10 minutes.

The filter paper along with the PET film was divided into two at the central portion in the width direction of the filter paper. One of the split pieces was finely cut in the length direction as indicated by broken lines in FIG. At this time, for the half of the indicator (Example 1), the end of the filter paper (width 2 mm) opposite to the end where the filter paper of the indicator is arranged is shown by a dashed line in FIG. was removed by half-cutting at the half-cutting position h. For the remaining half of the indicator (Comparative Example 1), the filter paper was not half-cut.

(evaluation)
(1) Concentration ratios R1 and R2, and the gradient of the concentration of the first color component. For the other divided piece, the filter paper part is separated from the end of the filter paper side with the PET film at a width of 2 mm from the end on the side where the filter paper is arranged. The sample was divided into four strips, and the first sample, second sample, third sample, and fourth sample were obtained in order from the ends. In Example 1, the first sample corresponds to the first edge portion, the second sample corresponds to the central portion, and the third sample corresponds to the second edge portion. In Comparative Example 1, the first sample corresponds to the first edge portion, and the fourth sample corresponds to the second edge portion. In Comparative Example 1, the concentration and absorbance of each component in the central portion were the average values of the numerical values of the second and third samples.

Then, from each sample, the first color component was extracted with ion-exchanged water, and the obtained liquid was concentrated or diluted so that the mass of the liquid obtained from each sample was the same. Then, 0.1 g of hydrogen peroxide solution with a concentration of 35% by mass was added to each liquid to color it. The amount of hydrogen peroxide added here is sufficient to convert all the iodide contained in each liquid into iodine. Colored liquids obtained from the first to fourth samples were designated as samples 1 to 4, respectively, and the absorbance at 350 nm was measured. 350 nm is an absorption wavelength characteristic of a component in which iodine produced by oxidation of potassium iodide with hydrogen peroxide is incorporated into starch. The ratio of the absorbance of sample 3 to the absorbance of sample 2 was calculated and used as the R1 ratio in Example 1. Further, the average value of the absorbances of Samples 2 and 3 was obtained, and the ratio of the absorbance of Sample 4 to this average value was obtained as the R1 ratio in Comparative Example 1. The R1 ratio of Example 1 was 1.40 and the R1 ratio of Comparative Example 1 was 3.69.

For Example 1, the absorbances at 350 nm of Sample 1, Sample 2, and Sample 3 are 0.030, 0.035, and 0.049, respectively, and the absorbance from the first edge to the second edge is (that is, the concentration of the first color component) increased. The concentration of starch into which iodine was incorporated (that is, the concentration of iodine produced) in each part, calculated from the absorbance of samples 1 to 3 by the above-described procedure, was 0.009% by mass in the first sample. , 0.010% by mass of the second sample, and 0.015% by mass of the third sample.

(2) Inspection Accuracy of Indicator For each of Example 1 and Comparative Example 1, the filter paper portion of the slit-shaped indicator was immersed in an aqueous hydrogen peroxide solution having a concentration of 35% by mass and then pulled out.
In the indicator of Example 1, the entire filter paper portion was substantially uniformly colored, confirming that the aqueous hydrogen peroxide solution contained hydrogen peroxide at an effective concentration. On the other hand, in the indicator of Comparative Example 1, the second edge portion was colored yellow before being immersed in the aqueous hydrogen peroxide solution. Further, in the indicator of Comparative Example 1, after immersion in the aqueous hydrogen peroxide solution, the second edge portion of the filter paper and its vicinity developed a dark color, making it possible to determine whether hydrogen peroxide was contained at an effective concentration. It was hard to come by.

<Example 2 and Comparative Example 2>
An aqueous solution c containing sodium sulfite as a reducing agent at a concentration of 2% by mass was prepared.
In addition to the aqueous solution a and the aqueous solution b, the aqueous solution c was added dropwise to the filter paper to spread each solution over the entire filter paper. Other than this, indicators were produced and evaluated in the same manner as in Example 1 and Comparative Example 1, respectively. The R1 ratio of Example 2 was 1.04 and the R1 ratio of Comparative Example 2 was 2.25.

Further, for Samples 1 to 4, the iodine concentration in each part was obtained in the same manner as in Example 1 and Comparative Example 1, and the iodine concentration obtained in each part in Example 1 and Comparative Example 1 was By subtracting from, the concentration (% by mass) of the reducing agent in each part was obtained. When the R4 ratios in Example 2 and Comparative Example 2 were determined, the R4 ratio in Example 2 was 0.92 (≈1), and the R4 ratio in Comparative Example 2 was 1.50.

For Example 2, the absorbances at 350 nm of Sample 1, Sample 2, and Sample 3 are 0.112, 0.119, and 0.124, respectively, and the absorbance from the first edge to the second edge is (that is, the concentration of the first color component) increased. The concentration of starch into which iodine was incorporated (that is, the concentration of iodine produced) in each part, which was calculated from the absorbance of samples 1 to 3 by the above-described procedure, was 0.035% by mass in the first sample. , 0.037% by mass of the second sample, and 0.086% by mass of the third sample.

When the evaluation (2) was performed for each of Example 2 and Comparative Example 2, the indicator of Example 2 exhibited a substantially uniform coloration over the entire filter paper portion, indicating that the aqueous hydrogen peroxide solution was excessively concentrated at an effective concentration. It was confirmed to contain hydrogen oxide. On the other hand, with the indicator of Comparative Example 2, whitish spots were observed on the second edge of the filter paper and its vicinity, making it difficult to determine whether hydrogen peroxide was contained at an effective concentration.

The indicator according to this embodiment can ensure high inspection accuracy. As such, the indicator is suitable for use in testing the concentration of various components of interest, such as oxidant indicators.

P: porous layer, S: base sheet, E1: first edge portion, E2: second edge portion, C: center portion, B: belt-like portion, H: half-cut trace, h: half-cut position

Claims (23)

A strip-shaped base sheet and a porous layer formed on one surface of the base sheet,
The porous layer is arranged at one end in the length direction of the base sheet, and has a first edge on the one end side, a second edge on the side opposite to the first edge, and the second edge on the side opposite to the first edge. a center portion located between one edge portion and the second edge portion;
The porous layer includes a first coloring component that detects a target component and reacts with each other to develop a color, and a second coloring component having a higher molecular weight than the first coloring component,
A ratio R1 (=C12/C1c) of the concentration C12 of the first coloration component at the second edge portion to the concentration C1c of the first coloration component at the center portion is 2.2 or less ,
a side end surface of the second edge portion of the porous layer is a half-cut surface;
The indicator , wherein the base sheet has a half-cut mark immediately below the half-cut surface . the porous layer comprises a strip located adjacent to the second edge ;
2. The indicator of claim 1 , wherein the strip is removable with respect to the base sheet. A strip-shaped base sheet and a porous layer formed on one surface of the base sheet,
The porous layer includes a first coloring component that detects a target component and reacts with each other to develop a color, and a second coloring component having a higher molecular weight than the first coloring component,
The porous layer is arranged at one end in the length direction of the base sheet, and has a first edge on the one end side, a second edge on the side opposite to the first edge, and the second edge on the side opposite to the first edge. a central portion located between one edge portion and the second edge portion; and a strip portion located adjacent to the second edge portion;
A ratio R1 (=C12/C1c) of the concentration C12 of the first coloration component at the second edge portion to the concentration C1c of the first coloration component at the center portion is 2.2 or less,
The indicator, wherein the band-shaped portion is removable with respect to the base sheet. 4. The indicator according to claim 2 or 3, wherein said strip includes said first coloration component and said second coloration component. Any one of claims 2 to 4, wherein the ratio R1 and the ratio R3 (=C13/C1c) of the concentration C13 of the first color component in the strip to the concentration C1c satisfy R3>R1. 1. Indicator according to item 1 . The ratio R1 and the ratio R2 (=C22/C2c) of the concentration C22 of the second color component at the second edge portion to the concentration C2c of the second color component at the center portion satisfy R1>R2. The indicator according to any one of claims 1 to 5 , which satisfies the relationship of An indicator according to any preceding claim, wherein said ratio R1 is equal to or less than 1.7. A strip-shaped base sheet and a porous layer formed on one surface of the base sheet,
The porous layer is arranged at one end in the length direction of the base sheet, and has a first edge on the one end side, a second edge on the side opposite to the first edge, and the second edge on the side opposite to the first edge. a center portion located between one edge portion and the second edge portion;
The porous layer includes a first coloring component that detects a target component and reacts with each other to develop a color, and a second coloring component having a higher molecular weight than the first coloring component,
In the indicator, the base sheet has a half-cut surface on a side end surface of the second edge portion of the porous layer, and has a half-cut mark immediately below the half-cut surface . The porous layer comprises a fiber aggregate,
The indicator according to any one of claims 1 to 8 , wherein said fiber assembly contains said first coloration component and said second coloration component. 10. An indicator according to claim 9 , wherein said fibrous assembly is paper or non-woven fabric. The indicator according to any one of claims 1 to 10 , wherein in said porous layer, the concentration of said first color component increases from said first edge toward said second edge. The target component is an oxidizing agent,
The first color component is an iodide that produces iodine in the presence of the oxidizing agent,
The indicator according to any one of claims 1 to 11 , wherein said second color component is starch. 13. The indicator of Claim 12 , wherein the iodide is potassium iodide. 14. An indicator according to claim 12 or 13 , wherein said porous layer further comprises a reducing agent for reducing said iodine. 15. The indicator according to claim 14 , wherein a ratio R4 (=Cr2/Crc) of the reducing agent concentration Cr2 at the second edge portion to the reducing agent concentration Crc at the central portion is less than 1.5. a preparation step of preparing a base sheet and a porous layer formed on one surface of the base sheet;
a diffusion step of diffusing a first coloring component that detects a target component and reacts with each other to develop a color and a second coloring component having a molecular weight larger than that of the first coloring component in the porous layer;
A method for producing an indicator, comprising a dividing step of dividing the porous layer into an end region where the concentration of the first color component is relatively high and the remainder by half-cutting. 17. The method of manufacturing an indicator according to claim 16 , further comprising removing said end regions from said base sheet. 17. or, in the diffusing step, the first coloration component and the second coloration component are simultaneously or individually applied to a part of the porous layer and diffused into the porous layer. 18. A method for manufacturing the indicator according to 17 . 19. The method according to any one of claims 16 to 18 , wherein in the diffusing step, the first coloration component and the second coloration component are simultaneously or individually dropped into the porous layer and diffused. How the indicator is made. The method of manufacturing an indicator according to any one of claims 16 to 19 , wherein in the dividing step, half-cut marks are formed on the base sheet. In the preparation step,
The base sheet having a width W1 and a length L1, and a width W2 (where W2<W1) and a length attached to regions other than both ends in the width W1 direction of the base sheet along the length L1 direction. preparing the strip-shaped porous layer having a thickness L2,
The method of manufacturing an indicator according to any one of claims 16 to 20 , wherein the end regions include both ends in the width W2 direction of the strip-shaped porous layer. The base sheet was cut into a strip having a width W3 (where W3 < L1) and a length L3 (where L3 < W1), and the porous layer was arranged at one end in the length L3 direction. 22. The method of manufacturing an indicator according to claim 21 , further comprising cutting out the indicator. In the step of cutting out the indicator,
23. The indicator according to claim 22 , wherein the base sheet is divided into two parts in the width W1 direction together with the porous layer so as to cross the center part of the strip-shaped porous layer, and is divided into a plurality of parts in the length L1 direction. manufacturing method.

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