JPS61264257A - Indicator for displaying remaining deodorizing power of deodorizer and deodorization system using said indicator - Google Patents

Abstract

PURPOSE:To know exactly the remaining deodorizing power of a deodorizer by depositing an acidic or basic material and pH indicator on a support and displaying the remaining deodorizing power of the deodorizer from the discoloration. CONSTITUTION:The indicator 2 and the deodorizer 3 are housed into a case 1 having ventilation grooves 11 and the case 1 is partitioned by a partition wall 12. The deodorizer 3 such as activated carbon is housed in a bag 31 made of a non-woven fabric having air permeability in one region 121 and the oxide such as sulfuric acid or base material such as NaOH is deposited on the indicator 2 such as silica gel in the other region 122 having a window part 13. The odorous materials in a refrigerator are absorbed into the deodorizer 3 and are at the same time absorbed through the vent grooves 11 to the indicator 2 if such deodorizing system 100 is rested in the refrigerator. The pH of the indicator 2 changes in this stage and therefore the color of the indicator changes to generate a discolored part 21. The change quantity thereof is proportional to the absoption quantity of the odorous materials. The remaining deodorizing function is thus known exactly by viewing the color change if the indicator is so set that the remaining deodorizing power of the deodorizer is lost when the color of the indicator changes.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an indicator that is suitable for use in refrigerators and displays the remaining deodorizing ability of a deodorizing agent, and a deodorizing system using the indicator.

(Prior Art) Deodorizers used to remove bad odors generated in refrigerators absorb odor substances and gradually lose their effectiveness.

In order to know when to replace the deodorizer, a deodorizing system has been proposed that incorporates an indicator that displays the remaining deodorizing ability of the deodorizer. For example, Japanese Unexamined Patent Publication No. 59-6059 discloses a deodorizing system using an aqueous chlorine dioxide solution. A part of the container that houses this chlorine dioxide aqueous solution is made of a breathable semipermeable membrane, and through this semipermeable membrane, odor substances in the atmosphere are oxidized by the chlorine dioxide in the container and lose their odor. On the other hand, water in the aqueous solution gradually evaporates through the semipermeable membrane. If the setting is made so that the deodorizing ability disappears while all or a predetermined amount of water evaporates, the aqueous solution acts as an indicator, and the remaining deodorizing ability can be determined according to the amount of water evaporated. In addition, a deodorizing system is also known in which a gel-like seaweed extract is stored as an indicator together with a deodorizing agent in a container. In this deodorizing system as well, the residual deodorizing ability of the deodorizer can be determined by the amount of water evaporated from the gelled seaweed extract.

However, even if a deodorizing system having the above-mentioned indicator is left in a refrigerator with different concentrations of odor substances, if the amount of water evaporation is the same, it will be displayed as if it had the same residual deodorizing ability. In fact, in a refrigerator with a high concentration of odorous substances, the deodorizing ability is lost within a short period of time. The indicator that displays the water evaporation amount only indicates the passage of one hour and does not accurately indicate the remaining deodorizing ability. Such indicators also have the disadvantage that the amount of moisture evaporated varies depending on the temperature, humidity, air volume, etc. of the atmosphere. Since evaporation is extremely slow with water alone, alcohol is sometimes added to promote evaporation, but this method is similar to the deodorizing system described above in that the amount of evaporation of the liquid is used as a guideline.

Furthermore, Japanese Patent Application Laid-Open No. 57-168158 discloses the use of a reduced dye as an indicator. This indicator absorbs oxygen from the atmosphere, changes into an oxidized form, and changes color.

This indicator is less affected by temperature and humidity than the indicator that uses water evaporation. However, if the amount of oxygen and temperature in the atmosphere are constant, regardless of the concentration of odorous substances, they will oxidize and change color after a predetermined period of time, so it is still not possible to accurately display the remaining deodorizing ability.

(Problem that the invention attempts to solve) The present invention solves the above-mentioned conventional drawbacks.

The purpose is to provide an indicator that accurately indicates the residual deodorizing ability of a deodorizing agent. Another object of the present invention is to provide an indicator that absorbs odorous substances and indirectly indicates the residual deodorizing ability of a deodorizing agent from the amount absorbed. Still another object of the present invention is to provide an indicator that displays the remaining deodorizing ability of a deodorant without being affected by temperature, humidity, air volume, etc. Yet another object of the present invention.

An object of the present invention is to provide an indicator in which volatile substances do not evaporate from the indicator. Still another object of the present invention is to provide a deodorizing system using the above-mentioned valuable indicator.

(Means for solving problems) The indicator for indicating the deodorizing ability of the deodorizing agent of the present invention is as follows.

The above object is achieved by carrying an acidic substance or a basic substance and a pH indicator on a support to display the remaining deodorizing ability of the deodorizing agent by color change. The deodorizing system of the present invention has an acidic or basic substance and a pH indicator supported on a support. It contains an indicator that indicates the residual deodorizing ability of the deodorizer by color change; and a deodorizer, thereby achieving the above object.

As the support supporting the pH indicator used in the indicator of the present invention, an inert, white to light-colored, colorable inorganic or organic material is used. Examples of such supports include silica gel; activated clay; zeolite; alumina; porous inorganic materials such as unglazed earthenware and pumice; synthetic resin foams such as polyurethane; synthetic or natural fibers and paper using such fibers. , thread, nonwoven fabric, etc. These supports 9 are usually fairly neutral, but acidic supports such as activated clay can be used as they are as indicators by supporting the pH indicator described below. These supports can be used in any desired shape, such as powder, granule, small block, or bead shape.

A nonvolatile compound is used as the acidic substance or basic substance supported on the support. Acidic substances are used to detect basic odorous substances, and basic substances are used to detect acidic odorous substances. Acidic substances include sulfuric acid, phosphoric acid, and malic acid. The amount of such an acidic substance supported varies depending on the type and shape of the support described below, but is usually 10-5 to 10-3% by weight of the support. For example, when using silica gel powder as a support, 10-5
~10-4% by weight is suitable. Basic substances include sodium hydroxide and potassium hydroxide. The amount of such basic substances supported is usually 10@-2 to 1% by weight of the support.

When supporting the above acidic substance, a compound that changes color at p) II to 6 is used as the pH indicator.

1m-Cresol Purple for such compounds.

Thymol blue, pentamethoxy red, p-xylenol blue, Tropeolin 00. quinaldine red, 2
・6-dinitrophenol, benzobrulin 4B, 2
・4-dinitrophenol.

Examples include hexamethoxy red, methyl yellow, direct purple, bromophenol blue, Congo red, methyl orange, tetrabromophenol blue, and bromochlorophenol blue. When supporting a basic substance, a compound that changes color at pH 8 to 13 is used as the pH indicator. Such compounds include 1
・3,5-trinitrobenzene, sodium trinitrobenzoate.

Indigo carmine, Tropeolin O, Nitramine.

Alizarin yellow GG, alizarin yellow R, Nile blue, thymolphthalein, Nile blue thymolphthalein, phenolphthalein, 0-cresol phthalein, thymol blue, p-xylenol blue, and the like.

The amount of the pH indicator supported varies depending on the type and form of the indicator. For example, when a 60 to 80 mesh silica gel powder is used as a support, the amount of pH indicator supported is 0.01% by weight or more, preferably around 0.05% by weight of the support. If there is too little pH indicator, it will be difficult to observe the color change. Although it may be carried in excess, there is no change in the colored state of the indicator even if it is supported in an amount of 1% by weight or more, and even if a large amount is used, it is wasteful. Since there is no difference in the detection sensitivity of odorous substances due to differences in the amount of pH indicator carried, an indicator with a desired color density can be obtained by adjusting the amount of pH indicator.

The indicator of the present invention comprises the above acidic substance and pi (indicator,
Alternatively, it can be obtained by dissolving a basic substance and a pH indicator in a suitable solvent, impregnating or coating the solution on a support, and then removing the solvent. The solvent may be any solvent as long as it can dissolve the acidic substance and pH indicator used.
Alcohols such as ethanol are preferably used.

By the way, the bad odor inside the refrigerator is the odor of the food itself or the odor caused by the food rotting. The inventors' research has revealed that such odorous substances are mainly basic or acidic. Basic odorants include 9 e.g.
These include ammonia, trimethylamine, methylamine, ethylamine, pyridine, indole, and skatole. The concentration of such basic odorous substances is high in the refrigerator, especially the concentration of ammonia and trimethylamine. Examples of acidic odorous substances include hydrogen sulfide, sulfurous acid, and formic acid.

Acetic acid, propionic acid, butyric acid, valeric acid, caproic acid.

Caprylic acid, acrylic acid, methacrylic acid, methyl mercaptan, ethyl mercaptan, propyl mercaptan,
These include allyl mercaptan, dimethyl sulfide, diallyl sulfide, dimethyl disulfide, diethyl sulfide, ethyl methyl sulfide, tetrahydrothiophene, formaldehyde, acetaldehyde, propionaldehyde, furfural, and benzaldehyde. Although the concentration of acidic odor substances in the refrigerator is relatively low.

Because the dark value of the odor is low, even a small amount can be misinterpreted as a bad odor. In particular, compounds that are perceived as bad smells in the refrigerator include hydrogen sulfide, methyl mercaptan, dimethyl sulfide,
Such as propionic acid.

Such basic or acidic odorous substances exist in the refrigerator in a gaseous state. When an odorous substance comes into contact with the indicator, a neutralization reaction occurs with the acidic or basic substance supported on the indicator, changing the pH of the indicator. Therefore, the color of the indicator changes when a predetermined pH value is reached. for example,
When a basic odor substance such as ammonia comes into contact with the indicator obtained by supporting sulfuric acid and thymol blue and a neutralization reaction occurs, the color of the indicator changes from red to yellow due to an increase in pH. For example, when the indicator of the present invention is placed in a transparent glass container, it reacts with odorous substances (absorbs odorous substances).
The indicator changes sequentially from the surface in contact with the outside air toward the inside. The length of the discolored region is proportional to the integrated value of the concentration of the odorant and the exposure time to the indicator, in other words, the amount of absorption into the indicator. Therefore, by visually comparing the discolored area and the undiscolored area of the indicator, it is possible to determine the relative amount of the odorous substance absorbed by the indicator (in other words, the relative amount of the odorous substance absorbed by the deodorizer described later).
1) It is possible to know the remaining capacity of the deodorizer indirectly. As mentioned above, the concentration of odorous substances in the refrigerator is relatively high because the concentration of basic odorous substances9 Usually, an indicator carrying an acidic substance is used, but depending on the type of food in the refrigerator, etc. Depending on the situation, an indicator carrying a basic substance is used as appropriate.

The deodorizing agent used in the deodorizing system of the present invention includes:

For example, a physical deodorizing agent or a chemical deodorizing agent can be used. Examples of deodorizing agents based on physical action include activated carbon and bead-shaped unglazed ceramics that absorb odorous substances; high-boiling solvents and surfactants that absorb and dissolve odorous substances. Deodorants based on chemical action include acetic acid, which neutralizes odorous substances,
Acids such as humic acid and salts such as sulfates and hydrochlorides; Unsaturated compounds such as methacrylic acid esters that undergo addition and polymerization reactions with odorous substances; Aldehydes that undergo condensation reactions with odorous substances; Form chelates with odorous substances Examples include chlorophyll (tea leaf extract); quaternary amine type anion exchange resins that perform ion exchange reactions with odorous substances; chlorine dioxide and potassium permanganate that oxidize and decompose odorous substances.

The deodorizing system of the present invention comprises, for example, an indicator 2 and a deodorizing agent 3 housed in a case 1 having a ventilation groove 11 as shown in FIG. The case 1 has a partition wall 12, and one area 121 partitioned by the partition wall 12 contains a deodorizer 39, such as activated carbon, in a bag 31 made of breathable non-woven fabric.
is stored. The indicator 2 is housed in the other region 122 across the partition wall 12 . A window 13 made of transparent plastic or the like is provided on the case surface of the indicator storage area 122, and discoloration of the indicator 2 can be visually observed from the outside through this window 13.

When such a deodorizing system 100 is left in a refrigerator.

Odor substances in the refrigerator are absorbed by the deodorizer 3 and at the same time, are absorbed by the indicator 2 through the ventilation groove 11. When the odor substance is absorbed by the indicator 2, the pH of the indicator 2 changes, so the color of the indicator changes and a discolored portion 21 appears. As the odor substance is absorbed into the indicator 2, a two-color change occurs sequentially from the surface (opening) of the indicator in contact with the outside air. The amount of change is proportional to the product of the concentration of the odorant and the exposure time of the indicator to the odorant, that is, the amount of absorption of the odorant. Therefore, if the setting is made so that the residual deodorizing ability of the deodorizer disappears when the color of the indicator stops changing, it is possible to accurately know the residual deodorizing ability of the deodorant by visually observing the state of the two-color change. can.

When the deodorizing agent is a light-colored, inert solid 2, for example beads made of unglazed pottery, it is also possible to prepare a deodorizing system by mixing the deodorizing agent and the indicator.

(Function) According to the present invention, as described above, an acidic substance and a pH indicator,
Alternatively, an indicator carrying a basic substance and a pH indicator can be obtained. This indicator absorbs odorants and adjusts its pH
The color changes depending on the change in color. Therefore, by appropriately selecting the type and amount of the acidic substance or basic substance and the type of pH indicator, an indicator that changes color when absorbing a desired amount of odorous substance can be obtained. Since the change (color change) in the indicator is not caused by evaporation of water or air oxidation, the conventional disadvantage that the indicator changes after a predetermined period of time is eliminated. There is also very little influence from ambient temperature, humidity, air volume, etc. Therefore, by appropriately setting the combination of the color change rate of the indicator and the deodorizing ability of the deodorizing agent, a deodorizing system that accurately indicates the remaining deodorizing ability of the deodorizing agent can be obtained. Since it is known whether the odor substance is basic or acidic depending on the type of food in the refrigerator, it is possible to appropriately use an indicator carrying an acidic substance and an indicator carrying a basic substance.

(Example) The invention will be explained below with reference to examples.

Daikyoku ■Kamijiri 0.01% sulfuric acid aqueous solution 0.5g and Thymol Blue 1
5mg to 40mI of ethanol! It was added to and dissolved. To this was added 30 g of 60-100 mesh silica gel powder with stirring. After stirring this suspension for another 2 to 3 minutes, it was placed in a hot air dryer and the ethanol was evaporated at 70°C.
It was dried to obtain an indicator.

A glass tube with an inner diameter of 5 m and a length of 50 m was vertically placed on a glass plate and adhered to obtain a cylindrical transparent container. This was filled with an indicator up to a height of 3R from the opening.

The cylindrical container containing the indicator was placed in a 201 polyethylene tank containing 3 ppm ammonia gas at 20°C.
It was left for 70 hours at 60% relative humidity. The length of the discolored area of the indicator was measured from the top filled with the indicator. The expected discoloration area (X) was calculated by substituting this length A (unit: fi) into the formula below. The results are shown in Table 1. The expected discoloration area is when the ammonia concentration is 0. It is expected that the indicator placed in the container will change color during 6 months at O5ppm.

30 x 70 sharp soil Two weeks The procedure was the same as in Example 1-(1) except that 100 to 200 mesoyu of silica gel was used and the amount of sulfuric acid aqueous solution was 1 g. The results are shown in Table 1.

The procedure was the same as in Example 1-(L) except that 30 to 50 mesoyu zeolite powder was used in place of the Daitoju Tojiri silica gel powder, and the amount of the sulfuric acid aqueous solution was 1 g. The results are shown in Table 1.

The procedure was the same as in Example 1-(11) except that 3 g of absorbent cotton was used in place of the Fuba Madara Jio silica gel powder. The results are shown in Table 1.

0.5g of 0.1% phosphoric acid aqueous solution instead of sulfuric acid aqueous solution
It is the same as Example 1-+11 except that it was used.

The results are shown in Table 1.

Yujo Otsuji! It is the same as Example 1-(1) except that quinaldine red was used instead of thymol blue.

The results are shown in Table 1.

It is the same as Example 1-(1) except that m-cresol purple was used instead of thymol blue. The results are shown in Table 1.

Two plates of potassium hydroxide 0.1g and phenolphthalein 1
5 mg was stirred and dissolved in a mixture of 40 ml of ethanol and 10 ml of water. After adding 60 to 100 mSO of silica gel to this while stirring, the mixture was further stirred for 10 minutes. This suspension was dried while being stirred at 110° C. using a magnetic stirrer equipped with a hot plate to obtain an indicator. This indicator was filled in the same cylindrical container as in Example 1-(1), and the expected discoloration area was determined in the same manner. The results are shown in Table 1. However, a polyethylene tank containing hydrogen sulfide gas was used instead of ammonia gas. The expected discoloration range in this example is hydrogen sulfide concentration of 0.01p.
The expected length (fm) is the length at which the indicator placed in the container is expected to change color over a period of 6 months at pm.

(Margins below) Fruit 1 λ Diameter 7 1. A transparent container with one end of a glass tube having a height of 50 mm sealed was filled with the support obtained in Example 1-(1) to a height of 45 fl. Two containers filled with indicators were prepared, and one of them was placed in a refrigerator (capacity: 2301, circulation type) that is normally used at home. I put another one into a refrigerator of the same type that was running empty. After being left for 6 months, the length of the discolored area of each indicator was measured. The results are shown in Table 2.

Comparison ± 70 m of seaweed extract gel (1.5% gel; 98.5% water) was placed in a transparent glass container with a diameter of 301 m and a height of 751 m.
Filled to a height of m. Prepare two of these and one of them
A refrigerator that is normally used at home (capacity 23i)
; circulation type). I put another one into a refrigerator of the same type that was running empty. After standing for 6 months, the decrease in gel height due to evaporation of water was measured. The results are shown in Table 2.

As shown in Table 2, in the conventional gel reduction type indicator (comparative example), the volume of the gel body decreases due to evaporation of water regardless of the presence or absence of odorants. On the other hand, 9 indicators of the present invention (Example 2)
absorbs odorous substances and changes color, but no change is observed in the absence of odorous substances.

A cylindrical container made of vinyl chloride resin having a diameter of 34 cm and a depth of 801 nm was filled with 30 g of activated carbon of 10 to 32 mSO as a deodorizing agent. Height 50 with one end sealed of glass tube with inner diameter 5n
A fin glass container was filled with the indicator obtained in Example 1-(11) to a height of 45 mm from the opening.The glass container filled with this indicator was placed on the outer wall of the above-mentioned vinyl chloride resin cylindrical container. Nine such deodorizing systems were prepared.Three of the deodorizing systems were installed in the back of the lower shelf of a household refrigerator under normal use.Additionally, three deodorizing systems were installed in the freezer of this refrigerator. The remaining three were placed in a refrigerator that was running empty.

After 3 months, deodorize the refrigerator, freezer, and empty refrigerator.
Each indicator was taken out and the length of the discolored area of each indicator was measured. The results are shown in Table 3.

In addition, the deodorizing agent used in each container,
It was placed in a 201 plastic tank containing 50 ppm of hydrogen sulfide gas, and the half-life of the hydrogen sulfide gas was measured.

The results are shown in Table 3.

Similar tests were conducted after 6 months and 12 months.

Separately, the half-life of hydrogen sulfide gas was measured using a deodorizing agent immediately after preparation. The results are shown in Table 3.

The half-life of hydrogen sulfide gas indicates the residual deodorizing ability of the deodorizer, so if there is a correlation between this half-life and the length of discoloration of the indicator, the residual deodorizing ability can be estimated by measuring the length of discoloration. .

(The following is a blank space) It is clear from Table 3 that the remaining deodorizing ability of the deodorizer can be accurately determined by measuring the length of the discolored region of the indicator.

Soushiban ↓ 5 g of a 10% aqueous sodium hydroxide solution and a 1% phenolphthalein ethanol solution were evenly applied to 10 g of a 60 μm thick filter paper and dried to obtain an indicator.

This was cut into a size of 5 mm x 50 tm. As shown in FIG.
It was sandwiched between two transparent vinyl chloride resin adhesive tapes 5 having a thickness of 0 μm and a width of 15 fins, and the three were brought into close contact. When the obtained laminate 6 was cut near the end and left in a refrigerator for general household use with the end surface 41 of the indicator 4 exposed as shown in FIG. The red color of phenolphthalein gradually disappeared from the cut end surface 41. The rate was about 21 per month. In this way, indicators that carry a basic substance and change color by absorbing odorous substances such as formic acid, balic acid, and hydrogen sulfide in the refrigerator can also be effectively used.

(Effects of the Invention) According to the present invention, an indicator that accurately indicates the residual deodorizing ability of a deodorizer can be obtained. The indicator does not change over time, regardless of the residual deodorizing ability of the deodorizer, and the temperature of the atmosphere.

It is almost unaffected by humidity and air volume.

Therefore, by combining such an indicator and a deodorizing agent, a deodorizing system that accurately indicates the residual deodorizing ability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an example of a deodorizing system using the indicator of the present invention, FIG. 2 is a side view showing an example of a laminate having another indicator of the invention, and FIG. FIG. 2 is a perspective view showing a cross section of the laminate taken along line X-X in the figure. 2.4... Indicator, 3... Deodorizer, 5... Adhesive tape. 21... Discolored area, 41... Indicator cut end surface, 10
0... Deodorizing system. that's all

Claims (1)

[Scope of Claims] 1. An indicator that displays the residual deodorizing ability of a deodorizer by color change, which has an acidic or basic substance and a pH indicator supported on a support. 2. The indicator according to claim 1, wherein the pH indicator changes color due to reaction of the acidic substance or basic substance with a basic or acidic odor substance in the atmosphere. 3. The indicator according to claim 1, wherein the acidic substance or basic substance is nonvolatile. 4. The indicator according to claim 1, wherein the residual capacity of the deodorizer can be known by visually comparing the discolored area and the non-discolored area. 5. An indicator comprising an acidic or basic substance and a pH indicator supported on a support and displaying the residual deodorizing ability of the deodorant by color change; and a deodorizing system containing the deodorizing agent. 6. The deodorizing system according to claim 5, wherein the pH indicator changes color due to reaction of the acidic substance or basic substance with a basic or acidic odor substance in the atmosphere. 7. The deodorizing system according to claim 5, wherein the acidic substance or basic substance is nonvolatile. 8. The deodorizing system according to claim 5, wherein the residual capacity of the deodorizer can be known by visually comparing the discolored area and the undiscolored area.