JPH0466518B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a usage period indicator that visually displays the elapsed period of time by changing color tone.

[Problems to be solved by conventional technology/invention]

For products that have an expiration date, the means to determine whether the expiration date has passed is as follows:
Types in which the product itself sublimates and disappears using a sublimation agent found in insect repellents and fragrances, types in which insecticides are decolored by heating using an electric mat method, and types in gel-like products where the active ingredients in the gel evaporate and the gel is removed. Examples include types that contract. However, among the products with an expiration date on the market, there are only a limited number of products that have a means to clarify the expiration date like the above type, and for the majority of products, it is impossible to determine the end of the expiration date. There are many cases. For this reason, consumers are usually unable to determine whether the product they are using is still effective or not.
There is waste and inconvenience caused by replacing a product with a new one sooner than necessary or continuing to use it even though it has become invalid, so it was desired to develop a method for determining the expiration date of this type of product. . In order to meet these demands, a composition for changing color tone over time has been proposed, for example, as in Japanese Patent Application Laid-Open No. 56-53461, which indicates the period of use by a change in color tone over time. The composition has a PH
It is characterized by containing a PH indicator with a color change between 0 and 7 and an acidic substance, and the coloring state of the PH indicator changes depending on the remaining amount of the acidic substance as it evaporates over time. It is. However, since the above composition does not have a method for controlling the volatilization state of the acidic substance, changes in the coloring state are affected by usage environmental conditions such as temperature, and as a result, it is difficult to accurately display the period. It is difficult to expect. That is,
The above method does not solve the drawbacks caused by leaving the period setting to the volatilization method itself, which is highly temperature dependent. The present invention has been made in view of the above circumstances,
The purpose is to provide a simple and highly safe expiration date indicator that can accurately determine the effective expiration date of a product without being affected by usage environmental conditions and is especially suitable for home use. .

[Means for solving the problem, effects of the invention]

In order to achieve the above object, the present invention provides a material (hereinafter referred to as a "carrier") that absorbs liquid materials such as paper or nonwoven fabric.
) contains a PH indicator that causes a color tone change at a specific PH, an alkaline substance, and a humectant, and is configured so that the color tone changes when the alkaline substance reacts with carbon dioxide gas in the air. It is something. That is, in the present invention, an alkaline substance and a PH indicator are mixed and dissolved in water, and a moisturizing agent is further added to impregnate a carrier with a mixed preparation solution, which is used after drying. By determining the amount of alkaline substances added in relation to the effective period of use, so that the color tone changes clearly when the remaining amount of alkaline substances reaches the color tone change sensitivity due to reaction with alkaline substances and the pH decreases. , it is possible to determine the end of the period of use. The carrier in the present invention includes paper, nonwoven fabric,
Impregnated paper or the like can be used. As the pH indicator, phenolphthalein, xylenolphthalein, thymolphthalein, etc., which have a pH of 10.5 to 8.0 and change in color tone, are suitable. In addition, sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide, or calcium hydroxide is suitable as the alkaline substance, and by adjusting the amount used, the color tone can be changed over a desired period of time. As shown in the example, it is also possible to change the color tone so that the clear color (colored) at the beginning of use becomes colorless (decolored) at the end of the effective use period. In order for an alkaline substance to absorb carbon dioxide gas in the air, a smooth function cannot be expected by simply attaching an alkaline substance and an indicator to a carrier; an appropriate amount of moisture is required. However, although a high moisture content is a suitable condition for absorbing carbon dioxide gas, on the other hand, if the moisture content is too high, the relative humidity increases during the rainy season, causing a dripping phenomenon from the carrier. In the present invention, a humectant is used to retain an appropriate amount of water, and at the same time, the humectant is used to control the absorption rate of carbon dioxide gas. In selecting a moisturizer, the inventors tested various substances and found that
It does not drip even if the relative humidity is maintained at room temperature for a long period of time (6 months to 1 year), maintains the moisture necessary for absorbing carbon dioxide, and also controls the absorption rate of carbon dioxide. Glycerin, reduced maltose starch syrup, propylene glycol,
Polyethylene glycol, sorbitol or sodium lactate have been found to be suitable. By adding an appropriate amount of these moisturizers, the period required for color change (for example, from colored to colorless) can be controlled without being affected by the environmental conditions of use, and the period of color change and the expiration date of the product can be adjusted. It was found that it was possible to match the colors and to clarify the color tone changes. The period indicator of the present invention, as shown by reference numeral 1 in FIGS. 1 and 2, can be formed into a sheet of any shape such as a rectangle, and the product form does not allow direct contact with alkaline substances. It is desirable that the product be stored in a transparent synthetic resin container 2 or the like in consideration of safety when used for household products. Of course, in this case, it is necessary to have a structure that allows contact with air, such as by providing a through hole 3 with a diameter of about 6 mm on the front surface of the container 2, and a A through hole 3 is formed in the front surface of the container 1 so that the indicator 1 of the present invention does not absorb carbon dioxide gas until the start of use by pasting a removable blocking film 4 such as vinylidene chloride.
It is necessary to seal it tightly. From the viewpoint of maintaining airtightness before use, it is preferable to use a synthetic resin with high gas barrier properties such as acrylonitrile as the material for the container 2. Note that container 1
By adhering a double-sided adhesive tape with release paper 5 or the like to the back side of the product, the display device of the present invention can be easily attached and used at any location on the product. The present invention having such a configuration can be used in a wide variety of ways, especially as an expiration date indicator for insect repellents, deodorizers, antifungal agents, etc. that do not change the sense of smell or the visual sense over time. It is useful as a.

[Example 1] A carrier with a thickness of 0.85 mm, a basis weight of 400 g/m ² , and a density
A 0.45 g/cm ³ impregnated paper was cut into 20 mm x 15 mm and used as a test piece. The weight of the test piece was 0.12g. Each test piece was impregnated with the impregnating solution shown in Tables 1 and 2 for 10 minutes, and then dried with hot air at 50°C for 3 hours to produce a test piece and a test article. The amount of impregnating liquid for the test item is 0.17g;
It was 0.19g. Both test products exhibited a deep red color. This test product was pasted on a sheet covered with plastic film such as polyethylene film, and left indoors, in the toilet, in a refrigerator, and in a car.
After several months, the color faded and became colorless.

【table】

【table】

[Example 2] A carrier having a thickness of 0.65 mm, a basis weight of 300 g/m ² , and a density
A 0.43 g/cm ³ impregnated paper was cut into 20 mm x 15 mm and used as a test piece. The weight of the test piece was 0.09g. Each test piece was impregnated with the impregnating solution shown in Tables 3 and 4 for 10 minutes, and then dried with hot air at 50°C for 3 hours to produce test pieces and specimens. The amount of impregnating liquid for the test item is 0.11g; the amount of impregnating liquid for the test item is
It was 0.13g. Both test products exhibited a deep blue color. This test product was pasted on a sheet covered with plastic film such as polyethylene film, and left indoors, in the toilet, in a refrigerator, and in a car.
After several months, the color faded and became colorless.

【table】

【table】

[Example 3] As a carrier, thickness is 0.46 mm, basis weight is 200 g/m ² , density
A 0.44 g/cm ³ impregnated paper was cut into 20 mm x 15 mm and used as a test piece. The weight of the test piece was 0.07g. Each test piece was impregnated with the impregnating solution shown in Tables 5 and 6 for 10 minutes, and then dried with hot air at 50°C for 3 hours to produce test pieces and specimens. The amount of impregnating liquid for the test item is 0.07g; the amount of impregnating liquid for the test item is
It was 0.09g. Both test products exhibited a deep blue color. This test product was pasted on a sheet covered with plastic film such as polyethylene film, and left indoors, in the toilet, in a refrigerator, and in a car.
After several months, the color faded and became colorless.

【table】

【table】 [Brief explanation of the drawing]

The drawings show an embodiment of the period indicator of the present invention, and FIG. 1 is a front view, and FIG. 2 is a sectional view taken along the line of FIG. 1. 1...Display device of the present invention, 2...Synthetic resin container, 3
...Through hole, 4...Blocking film, 5...Adhesive tape.

Claims (1)

[Scope of Claims] 1 A carrier such as paper or nonwoven fabric contains a PH indicator that changes color tone at a specific pH, an alkaline substance, and a humectant, and the color tone changes when the alkaline substance reacts with carbon dioxide gas in the air. A usage period indicator characterized by being configured to change. 2 Claim 1, characterized in that the PH indicator is one that is accompanied by a color tone change between PH10.5 and 8.0.
Use period indicator as stated in section. 3. The use period indicator according to claim 1 or 2, wherein the PH indicator is phenolphthalein, xylenophthalein, or thymolphthalein. 4. The use period indicator according to any one of claims 1 to 3, wherein the alkaline substance is sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide, or calcium hydroxide. . 5. The use period indicator according to any one of claims 1 to 4, wherein the moisturizing agent is glycerin, reduced maltose starch syrup, propylene glycol, polyethylene glycol, sorbitol, or sodium lactate.