JPS59135364A - Oxygen detecting agent - Google Patents

Abstract

PURPOSE:To obtain an inexpensive and safe oxygen detecting agent easy to handle and capable of detecting even low concn. oxygen in an atmosphere, by blending at least one compound selected from a group consisting of a phosphite or a hypophosphite and redox coloring matter. CONSTITUTION:As a phosphite or a hypophosphite constituting an oxygen detecting agent, there is an alkali metal salt or alkaline earth metal salt of phosphorous acid or hypophosphorous acid and a sodium salt is preferred. As an especially pref. compound, sodium phoshite is designated. In addition, these metal salts are used even in a hydride form having water of crystallization without any hindrance. The redox coloring matter being the other one component is coloring matter showing different colors by an oxidized state or a reduced state and, for example, Meldola's blue is represented. In a blending ratio, there is not limit even if the compounding amount of the redox coloring matter is one capable of developing function as the oxygen detecting agent but said coloring matter is usually compounded in an amount of 0.001-13wt%, pref., 0.01-5wt% on the basis of the sum amount of at least one compound selected from the group consisting of the phosphite and hypophosphite and the redox coloring matter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen detector, and more specifically, an oxygen detector comprising at least one selected from the group consisting of phosphites and hypophosphites and a redox dye. This relates to a detection agent.

Oxygen detectors allow the presence or absence of oxygen in a sealed atmosphere1 to be determined with the naked eye by a change in color tone, and the change in color tone is different in the presence and absence of oxygen. It has the great advantage of being reversible.

In particular, with the recent development of so-called coated plastic films coated with vinylidene chloride resin for food packaging, gas barrier properties against inorganic gases such as oxygen and carbon dioxide have rapidly improved, resulting in vacuum packaging, gas exchange packaging,
Various packaging methods have been developed for the purpose of removing oxygen, such as packaging using oxygen absorbers, and their use is rapidly increasing.

Foods packaged using these various packaging methods are all inexpensive and are manufactured in large numbers. When analyzing oxygen in the air surrounding the packaging of these foods using a conventional oxygen gas analyzer, such as a polarographic analyzer, a galvanic cell analyzer, or a stabilized zirconia analyzer, the packaging In order to sample the gas inside the container or bag, it is necessary to make a hole in the container or bag, which not only looks unsightly but also may impair the oxygen gas barrier performance. Furthermore, all of these analyzers are expensive and require a considerable amount of analysis time, and therefore cannot be said to be a good analysis method from an economical point of view.

On the other hand, oxygen detectors can be placed in the same atmosphere as the food by enclosing it in the packaging of the food, etc., without causing any damage to the packaging container or bag. Since it has the great advantage of being able to determine the presence or absence of oxygen with the naked eye in a short period of time, there is a demand for the development of an inexpensive, safe, and more effective oxygen detection agent.

Currently, liquid or solid oxygen sensing agents are known to meet this demand, but none of them are satisfactory. For example, an oxygen detecting agent consisting of the redox dye methylene blue, sugars, and sodium hydroxide is used as an oxygen detecting agent when performing anaerobic fermentation in the fermentation industry. The problem is that it reacts during storage and loses its original function as an oxygen detector.

Oxygen detection agents are also known that contain reducing agents such as hydrosulfides, dithionites, ferrous salts, etc. and redox dyes as essential components, but the oxygen detection sensitivity varies depending on the oxygen concentration [approximately 0.1 volume]. Therefore, it is inappropriate especially when applied to foods that are affected by trace amounts of oxygen.

Therefore, the present inventors conducted repeated studies to develop an oxygen detector that is inexpensive, safe, and easy to handle, and can even detect low concentrations of oxygen in the atmosphere. I found it.

That is, the present invention is an oxygen sensing agent comprising at least one selected from the group consisting of phosphites and hypophosphites and a redox dye.

The arsenite solution phosphite constituting the oxygen detecting agent of the present invention includes phosphorous acid, an alkali metal salt or an alkaline earth metal salt of hypophosphorous acid, and preferably sodium salt, potassium salt, etc. salt, calcium salt, magnesium salt, barium salt, etc. Specific examples of particularly preferred compounds include lithium phosphite, magnesium phosphite,
Examples include sodium hypophosphite and calcium hypophosphite.

Moreover, there is no problem even if these metal salts are hydrates containing water of crystallization.

Further, the redox dye, which is another component constituting the oxygen detecting agent of the present invention, is a dye whose color tone differs depending on the oxidation state and reduction state, and includes, for example, methylene blue, new methylene blue, isenmethylene blue, toluidine blue, and acid. Blue, methylene green, safranin, melt trouble, etc.

In the present invention, the blending ratio of at least one selected from the group consisting of phosphites and hypophosphites and the redox dye is such that the blended amount of the redox dye functions as an oxygen detector. There is no particular limit as long as the amount is present, but the amount of redox dye is usually 0.001 to 0.001 to the total amount of at least one selected from the group consisting of phosphites and hypophosphites and the redox dye. 13 weight ratio, more preferably 001 to 5
It is preferable to use the weight section. Redox dye is o, ooi
If it is less than the weight factor, the resulting oxygen detecting agent will be less colored, and it will be difficult to judge the change in color tone due to the presence or absence of oxygen.
Even if a large amount is added due to its heavy weight, the degree of coloring does not increase, and since dyes are generally expensive, this results in an economic loss, which is not preferable.

A major feature of the oxygen detector of the present invention is that it has higher oxygen detection sensitivity than conventional oxygen detectors and retains the ability to detect even trace amounts of oxygen. That is, conventional oxygen detecting agents, such as oxygen detecting agents made of a combination of methylene blue, sulfur hydroxide, and saccharides, exhibit color tones between oxidized and reduced forms when the oxygen concentration in the atmosphere is around 0 to 1 volume. On the other hand, the oxygen detecting agent of the present invention changes its color tone at an even lower oxygen concentration, that is, at an oxygen concentration of about 0.05% by volume. For example, it can be applied to cut rice cakes, etc.

The presence of water is necessary for the oxygen detection sensitivity of the present invention to function. Therefore, for example, water may be added during the production of the oxygen sensing side, or an inert crystal water-containing compound that does not impair its function as an oxygen sensing agent, such as sodium sulfate decaqueous phase, sodium carbonate decahydrate, etc. may be added.

Furthermore, when packaging high-moisture foods, water or crystal water-containing compounds should not be added to the oxygen detecting agent of the present invention, since the partial pressure of water vapor in the packaging container or bag will increase. Water can be replenished.

The amount of coexisting water in which the oxygen detecting agent according to the present invention effectively exhibits its function is determined by at least one compound selected from the group consisting of phosphites and hypophosphites [hereinafter referred to as (hypophosphites)] Total amount of salt compound] and redox dye 10
Per 0 parts by weight, preferably 01 parts by weight or more, more preferably 05 parts by weight or more. If the amount of coexisting water is less than this, the function will not be fully exerted because the amount of the (hypo)phosphite compound and redox dye dissolved in the water will be small.

It is preferred that the amount be 25 parts by weight or less, and this can prevent water from rising to the surface of the tablet when the oxygen detector is molded, for example, tableted.

If desired, fillers, alkaline compounds, dyes, etc. can be added to the oxygen detecting agent of the present invention as long as the function as an oxygen detecting agent is not impaired.

Extending agents include silica, silica alumina, alumina, silica magnesia, zeolite, quartzite, silica gel, kaolin, talc and the like.

In addition, in order to adjust the rate of change in color tone of redox dyes or to provide oxygen detection function in carbon dioxide atmosphere, alkali metal and alkaline earth metal hydroxides, carbonates, hydrogen carbonates, and silicic acids are added. Alkaline compounds such as salts may be added.

Conventional oxygen detectors have a major drawback in that, in a carbon dioxide atmosphere such as in carbon dioxide gas replacement packaging, alkaline compounds in the detector, such as sodium hydroxide, react with carbon dioxide and do not function as oxygen detectors. Was. However, the oxygen detecting agent of the present invention can be made to function as an oxygen detecting agent even in a carbon dioxide atmosphere by adding an alkaline compound such as a hydrogen carbonate, such as a sodium salt, a potassium salt, or a magnesium potassium salt. This is because the presence of bicarbonate lowers the pH of the oxygen sensing agent to such an extent that it does not absorb carbon dioxide gas.

The preferred blending amount of the above-mentioned extender and alkaline compound is (next) the total amount of the phosphite compound and the redox dye is 10
The amount is 10 to 1000 parts by weight relative to 0 parts by weight. Further, when a hydrogen carbonate is added for the purpose of detecting oxygen in the presence of carbon dioxide gas, a more preferable amount is 100
~800 parts by weight.

When producing the oxygen sensing agent of the present invention, at least one selected from the group consisting of phosphites and hypophosphites, a redox dye, water, an alkaline compound added as desired, an extender, There are no restrictions on the order of addition of dyes, etc.

The oxygen detecting agent of the present invention can be used in the form of a powder obtained by simply mixing each component, or as a tablet formed by a tablet molding machine, etc., or can be used in any form such as an ink formed by using the oxygen detecting agent of the present invention as a pigment. It can also be used in any form.

In any case, it is advisable for food hygiene and safety to wrap at least one side with a film with high oxygen permeability to prevent direct contact with food. However, even in that case, in order to not impair the original function of the oxygen-sensing agent, it is necessary to use a small amount of packaging material (some of which is transparent) so that the color tone of the oxygen-sensing agent can be judged with the naked eye. is necessary.

The oxygen detecting agent of the present invention can be used in packaging methods such as vacuum packaging, gas displacement packaging, and methods using oxygen absorbers used to prevent and preserve fresh foods, processed foods, organic medicines, metal products, etc. It is possible to detect incomplete degassing and poor sealing of containers or bags.

In addition, the oxygen detecting agent of the present invention has reversibility in color change in the presence and absence of oxygen, which prevents mechanical damage during the distribution stage of the package, such as the formation of pinholes and the sealing surface. It is also possible to detect peeling, etc.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Examples 1 to 6 Redox dyes, phosphites or hypophosphites, and other additives listed in Table 1 were thoroughly mixed to obtain oxygen-sensing powders. Place this in the atmosphere shown in Table 1 and observe the change in color tone of the oxygen detector Example 7, Comparative Example 1 Redox dyes and hypophosphites listed in Table 2 (Example)
Alternatively, glucose (comparative example) and other additives were thoroughly mixed to obtain an oxygen detector powder.

This was placed under an atmosphere as shown in Table 2, and the color tone of the oxygen detector was observed. As shown in the results in Table 2, it is clear that the oxygen sensing agent of the present invention can detect trace amounts of oxygen.

Example 8, Comparative Example 2 Phosphite (Example) or glucose (Comparative Example), bicarbonate, and other additives were thoroughly mixed with the redox dye listed in Table 6 to obtain an oxygen-sensing powder. Ta. This was placed in an atmosphere containing carbon dioxide as shown in Table 6, and the color tone of the oxygen detector was observed.

As shown in the results in Table 6, it is clear that the oxygen detector of the present invention fully exhibits its function even under a carbon dioxide atmosphere.

Claims (1)

[Claims] 1. An oxygen sensing agent comprising at least one member selected from the group consisting of phosphites and hypophosphites and a redox dye.