JP2015194332A - Cold insulation tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold insulation tool capable of easily performing a visual acknowledgment of whether or not a cooled state corresponds to an object state.SOLUTION: A cold insulation tool comprises a composition for cold insulation including water, a deposited composition, a non-deposited composition and a pH indicator. The deposited composition is deposited when the composition for cold insulation is frozen and does not correspond to the pH indicator. The non-deposited composition is not deposited when the composition for cold insulation is frozen and does not correspond to the pH indicator. The composition for cold insulation has pH(A) of 7.0 or more and 11.5 or less when all the deposited compositions and included compositions except water are replaced with water, pH(B) of 2.7 or more and 9.0 or less when all the non-deposited composition and included compositions except water are replaced with water. pH(A) and pH(B) indicate values in pH ranges different from each other of three pH ranges, i.e. values of pH lower than a color changed range of the pH indicator, pH in the color changed range, and pH higher than the color changed range.

Description

  The present invention relates to a cold insulator provided with a cold insulating composition in which a color change during cooling can be easily visually recognized.

The cold insulator is widely used for cold storage during storage and transportation of various fresh products, and is usually used repeatedly. Such a cold-retaining tool includes a cold-retaining composition having a cold-retaining action, and is configured by enclosing the cold-retaining composition in a thermally conductive container.
As the composition for cold insulation, those containing a colorant are known so that the presence thereof can be easily visually recognized from the outside of the cold insulation device. For example, the composition for cold insulation colored with a dye is enclosed. A cold insulator whose disclosing amount can be easily confirmed from the outside is disclosed (see Patent Document 1).

JP 2006-97984 A

  However, the cold insulator described in Patent Document 1 is difficult to visually check the cooling state, such as the presence or absence of freezing, even if the cold-keeping composition contains a dye, and it is at a desired temperature that can be kept cold. There is a problem that the cold insulator is sufficiently cooled until it is difficult to visually check the cooling state.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the cooler which can be visually recognized easily whether a cooling state exists in the target state.

In order to solve the above-mentioned problems, the present invention is a cold insulator provided with a cold insulation composition containing water, a precipitation component, a non-deposition component and a pH indicator, wherein the precipitation component is a freezing of the cold insulation composition. It is a component that sometimes precipitates and does not correspond to the pH indicator, and the non-precipitated component does not precipitate when the composition for cold insulation is frozen and does not correspond to the pH indicator, and the composition for cold retention The pH (A) when all the components other than the precipitated component and water are replaced with water is 7.0 to 11.5, and all the components other than the non-precipitated component and water are replaced with water. PH (B) of 2.7 to 9.0, pH (A) and pH (B) are lower than the color change range of the pH indicator, the color change range pH, and the color change range Of the three pH ranges with higher pH, To show the value of pH range which makes providing cold tool according to claim.
In the cold insulator of the present invention, it is preferable that the precipitation component is an inorganic salt and the non-deposition component is a thickener.

  ADVANTAGE OF THE INVENTION According to this invention, the cooler which can be visually recognized easily whether a cooling state exists in the target state is provided.

The cold insulation device according to the present invention is a cold insulation device provided with a cold insulation composition containing water, a precipitation component, a non-deposition component, and a pH indicator, and the precipitation component is precipitated during freezing of the cold insulation composition. The non-precipitating component is a component that does not precipitate during freezing of the cold-retaining composition and does not fall under the pH indicator, and the cold-retaining composition comprises the precipitation component and The pH (A) when all the components other than water are replaced with water is 7.0 or more and 11.5 or less, and the pH when all the components other than the non-precipitated component and water are replaced with water ( B) is not less than 2.7 and not more than 9.0, and pH (A) and pH (B) are lower than the color change range of the pH indicator, the pH of the color change range, and higher than the color change range. Different pH ranges among the three pH ranges Characterized in that it presents a value.
In such a cooler, since the color of the composition for cooling that reflects the presence or absence of color development of the pH indicator largely changes before and after freezing, the cooling state is a target state (a state in which the object can be sufficiently cooled). Or easily visible. And the color of the composition for cold preservation before and after freezing does not mainly reflect the color of content components other than pH indicators, such as the said precipitation component and a non-deposition component.

  It is preferable that pH (A) and pH (B) are pH at the temperature at which the pH indicator is dissolved in the composition for cold preservation.

The pH (A) corresponds to the pH of the precipitation component-containing water (for example, precipitation component aqueous solution) containing only the precipitation component with the same content (mass percent) as the content (mass percent) in the composition for cold preservation. . The pH (A) is preferably 11.2 or less, and more preferably 10.8 or less. Moreover, it is preferable that pH (A) is 7.2 or more, and it is more preferable that it is 7.4 or more.
pH (B) is the pH of non-precipitated component-containing water (for example, non-precipitated component aqueous solution) containing only the non-precipitated component at the same content (mass%) as the content (mass%) in the composition for cold preservation. It corresponds to. The pH (B) is preferably 8.8 or less, and more preferably 8.4 or less.

The cold-retaining composition is, for example, a combination of components that can adjust the acidity of the cold-retaining composition as the precipitation component and the non-deposition component, and more specifically, affects the color development of the pH indicator. The precipitating component and the non-precipitating component to be provided are used in combination with those having a predetermined concentration of aqueous solution having a pH within a specific range. By combining the pH indicator, the color change depending on the color change or presence / absence of the pH indicator is remarkably increased.
Hereinafter, each component will be described.

The said precipitation component functions as one component of a cryogen, and the freezing temperature of the composition for cold preservation is mainly determined by the kind and quantity.
The precipitation component does not correspond to the pH indicator, and is a component that precipitates as a crystal or amorphous (amorphous) when the composition for cold insulation is frozen, and is involved in the color change of the composition for cold preservation by precipitation. Is.
The said precipitation component may be used individually by 1 type, and may use 2 or more types together.

Before freezing, preferably in the composition for cold preservation at 0 ° C. or higher, the larger the amount of the precipitated component dissolved, the more the amount of the precipitated component dissolved is 90% by mass or more. It is preferably 95% by mass or more, more preferably 98% by mass or more, and particularly preferably 100% by mass (total amount).
Further, in the composition for cold preservation after freezing, the amount of the precipitated component is preferably as the amount of the deposited component is larger, and the amount deposited is preferably 90% by mass or more of the total amount of the deposited component. , 95% by mass or more, more preferably 98% by mass or more, and particularly preferably 100% by mass (total amount).

  The precipitation component is preferably an inorganic salt.

As the metal ions in the cations constituting the inorganic salt, ions of alkali metals such as lithium ions (Li ⁺ ), sodium ions (Na ⁺ ), potassium ions (K ⁺ ); magnesium ions (Mg ²⁺ ), calcium ions ( Ions of alkaline earth metals such as Ca ²⁺ ; ions of transition metals such as iron ions (Fe ³⁺ , Fe ²⁺ ), copper ions (Cu ²⁺ , Cu ⁺ ); zinc ions (Zn ²⁺ ), aluminum ions (Al ³⁺⁾ And ions of Group 12 or Group 13 metals such as
Examples of the non-metal ion in the cation constituting the inorganic salt include ammonium ion (NH ₄ ⁺ ).

As anions constituting the inorganic salt, halogen ions such as chloride ions (Cl ⁻ ), bromide ions (Br ⁻ ), iodide ions (I ⁻ ), sulfate ions (SO ₄ ²⁻ ), nitrate ions (NO) ₃ ^-); carbonate ions _(CO ^{3 2-);} bicarbonate ion (HCO ₃ ^-); hydrogen sulfate ion (HSO ₄ ^-); phosphoric acid ion _(PO ^{4 3-);} hydrogen phosphate ions _(HPO ^{4 2-} ); Dihydrogen phosphate ion (H ₂ PO ₄ ⁻ ); sulfite ion (SO ₃ ²⁻ ); thiosulfate ion (S ₂ O ₃ ²⁻ ); chlorate ion (ClO ₃ ⁻ ); perchlorate ion ( ClO ₄ ⁻ ); having a group formed by removing a hydrogen ion (H ⁺ ) from an acid group such as a carboxy group (—C (═O) —OH) or a sulfo group (—S (═O) ₂ —OH). An ion etc. can be illustrated.

The inorganic salt is not particularly limited, but alkali metal chlorides such as sodium chloride (NaCl) and potassium chloride (KCl); hydrochlorides such as ammonium chloride (NH ₄ Cl); sodium sulfate (Na ₂ SO ₄ ) and sulfuric acid Potassium (K ₂ SO ₄ ), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), magnesium sulfate (MgSO ₄ ), aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), nickel sulfate (NiSO ₄ ), alum (AlK (SO ₄ ) ₂ ), sulfates such as ammonium alum (Al (NH ₄ ) (SO ₄ ) ₂ ); sodium nitrate (NaNO ₃ ), potassium nitrate (KNO ₃ ), ammonium nitrate (NH ₄ NO ₃ ), calcium nitrate tetrahydrate things _{(Ca (NO 3) 2 ·} 4H 2 O), or calcium nitrate (Ca _{(NO 3) 2)} Salt; potassium bicarbonate (KHCO _3), hydrogen carbonates such as sodium bicarbonate (NaHCO _3);; carbonates such as potassium carbonate _(K 2 CO ₃₎ Calcium chloride (CaCl _2), magnesium chloride (MgCl ₂₎ Alkaline earth metal chlorides such as sodium dihydrogen phosphate (NaH ₂ PO ₄ ), disodium hydrogen phosphate (Na ₂ HPO ₄ ), potassium dihydrogen phosphate (KH ₂ PO ₄ ), dihydrogen phosphate Hydrogen phosphates such as potassium (K ₂ HPO ₄ ), ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ), diammonium hydrogen phosphate ((NH ₄ ) ₂ HPO ₄ ); trisodium phosphate (Na ₃ perchloric acid; chlorate and potassium chlorate (KClO _3); sulfites such as sodium sulfite _{(Na 2 SO 3); PO} 4) phosphates, such as Thiosulfates such as sodium thiosulfate _{(Na 2 S 2 O 3)} ;; potassium bromide (KBr), alkali metal bromides such as sodium bromide (NaBr); iodine thorium (NaClO ₄₎ perchlorate such as Examples thereof include alkali metal iodides such as potassium iodide (KI) and sodium iodide (NaI); borate salts such as borax (Na ₂ B ₄ O ₇ ).
The said inorganic salt may be used individually by 1 type, and may use 2 or more types together.

The inorganic salts are hydrochloride, sulfate, nitrate, carbonate, hydrogen phosphate, bicarbonate, phosphate, alkali metal chloride, alkaline earth metal chloride, sulfite, chlorate, One or more selected from the group consisting of perchlorates, thiosulfates, alkali metal bromides, alkali metal iodides and borates are preferred.
The inorganic salt is selected from the group consisting of hydrochloride, sulfate, nitrate, carbonate, hydrogen phosphate, hydrogen carbonate, phosphate, alkali metal chloride and alkaline earth metal chloride. More preferably, it is at least one kind.
By using such an inorganic salt, the composition for cold preservation has a large color change before and after freezing and is excellent in handleability.

  The content of the precipitation component of the composition for cold insulation is preferably such that the pH (A) described later falls within a predetermined range, preferably 0.1 to 12% by mass, and 0.1 to 10% by mass. % Is more preferable, and it may be 0.5 to 5% by mass.

The non-precipitated component is a component that does not precipitate when the composition for cold preservation is frozen and does not correspond to the pH indicator. In the present specification, “the non-precipitating component does not precipitate when the cryogenic composition is frozen” means that the non-precipitating component is solidified while being dissolved in water when the cryogenic composition is frozen. However, it is presumed that the non-precipitating component molecules are solidified without being aggregated in a large amount and surrounded by water molecules, and a large amount of the non-precipitating component molecules are aggregated and solidified. Presumed not to be in a state.
The said non-precipitating component may be used individually by 1 type, and may use 2 or more types together.

  In the composition for cold preservation before freezing and after freezing, the amount of the non-precipitated component is preferably as small as the amount of the non-precipitated component, and the amount of the non-precipitated component deposited is 10% by mass or less. It is preferably 5% by mass or less, more preferably 2% by mass or less, and particularly preferably 0% by mass (the total amount is not precipitated).

  The non-precipitating component is preferably a thickener or a surfactant, and more preferably a thickener.

The thickening agent is not particularly limited, but acrylic polymers such as polyacrylic acid and sodium polyacrylate (compound having a polyacrylic acid skeleton); carboxyalkyl celluloses such as carboxymethylcellulose (CMC); guar gum; hydroxypropyl guar gum and the like Examples include hydroxyalkyl guar gum; pectin; xanthan gum; tamarind gum; carrageenan; and alkylene glycol such as propylene glycol.
The said thickener may be used individually by 1 type, and may use 2 or more types together.

The thickener is preferably at least one selected from the group consisting of acrylic polymers, carboxyalkyl cellulose, xanthan gum, guar gum, hydroxyalkyl guar gum, pectin, tamarind gum, carrageenan and alkylene glycol.
The thickener is more preferably one or more selected from the group consisting of acrylic polymers, carboxyalkyl cellulose, xanthan gum, guar gum, and hydroxyalkyl guar gum.
By using such a thickener, the composition for cold preservation has a large color change before and after freezing and is excellent in handleability.

The surfactant is not particularly limited, but is an alkyl sulfate such as sodium dodecyl sulfate; an alkyl carboxylate such as sodium decanoate; an N-alkyl acrylamide such as N-isopropylacrylamide; a polyoxyethylene octyldodecyl ether or the like. Examples thereof include ethylene dialkyl ethers; polyoxyethylene monoalkyl ethers such as polyoxyethylene lauryl ether; polyoxyethylene monoalkenyl ethers such as polyoxyethylene oleyl ether.
The said surfactant may be used individually by 1 type, and may use 2 or more types together.

  The content of the non-precipitating component in the composition for cold preservation is preferably an amount such that pH (B) described later falls within a predetermined range, preferably 0.1 to 10% by mass, and 0.3 to More preferably, it is 4% by mass.

  In the composition for cold preservation, it is preferable that the precipitation component is an inorganic salt and the non-deposition component is a thickener. Such a composition for cold preservation has a large color change before and after freezing, and is excellent in handleability.

  The pH indicator (acid-base indicator) determines the color of the composition for cold preservation by reflecting the presence or absence of color development. The composition for cold preservation changes a color before and after freezing by containing a pH indicator.

The pH indicator may be a known one and is not particularly limited.
The pH indicator has a pH range in which the color change is observed, that is, a color change range. A pH indicator exists in a solution in a dissociated form and an undissociated form, and a dissociation equilibrium is established between them. The dissociated form and the undissociated form have different colors. Then, the equilibrium is remarkably offset in either the dissociated form or the undissociated form, and only one color is seen. In the color change range, the pH indicator is mixed in an amount that can be compared between the dissociated form and the undissociated form, and a mixture of both colors is observed ("Chemical Dictionary Dictionary 39th Edition, 2006 9"). May 15 ", Kyoritsu Publishing Co., Ltd.)).

  The pH indicator in the present invention preferably has a color change range (pH) in the range of 2.8 to 11.0. Table 1 illustrates the main pH indicators. Table 1 shows the color change range and color change together with the corresponding pH indicator. “Color change (low pH → high pH)” in Table 1 means that the pH indicator changes when the pH of the liquid containing the pH indicator changes from a specific value to a higher value. For example, “red → yellow” indicates that the pH indicator changes the color of the liquid from red to yellow in the process of increasing the pH of the liquid.

  The pH indicator may be used singly or in combination of two or more, but usually it is preferable to use one singly.

  The content of the pH indicator in the cold-retaining composition is not particularly limited as long as the intended color change of the cold-retaining composition is achieved, but is preferably 1 to 30 ppm, and more preferably 5 to 20 ppm. .

  The composition for cold preservation may contain, in addition to water, precipitated components, non-precipitated components, and pH indicator, other components not corresponding to these within the range not impairing the effects of the present invention. As said other component, well-known various additives, such as solvents other than water and antiseptic | preservative, can be illustrated.

The solvent is preferably one that can dissolve the precipitation component, the non-precipitation component, and the pH indicator, and examples of such a solvent include alcohol.
The said solvent may be used individually by 1 type, and may use 2 or more types together.

Water and the solvent function as one component of a cold-retaining agent, and the freezing temperature of the composition for cold-retention is determined mainly by the kind and amount of the precipitation component.
In the composition for cold preservation, the ratio of the content of the solvent to the total content of water and the solvent is preferably 10% by mass or less, more preferably 5% by mass or less, and 2% by mass or less. It is particularly preferred.

  Examples of the preservatives include food preservatives and antioxidants, and examples include sodium pyrithione, paraben (paraoxybenzoate ester), protamine, and organic nitrogen sulfur compounds.

  The composition for cold preservation is the precipitation component, non-deposition component, and pH indicator with respect to the total content of components other than water and the solvent (the precipitation component, non-deposition component, pH indicator, and other components other than the solvent). The ratio of the total content is preferably 90% by mass or more, more preferably 95% by mass or more, and may be 100% by mass. When the ratio of the total content is equal to or higher than the lower limit value, the color of the cold-retaining composition changes more greatly before and after freezing.

  The composition for cold preservation has a content of the precipitation component of 0.1 to 12% by mass, a content of the non-deposition component of 0.1 to 10% by mass, and a content of the pH indicator of 1 to 1%. Particularly preferred is 30 ppm. Such a composition for cold preservation has a large color change before and after freezing, and is excellent in handleability.

Preferred examples of the composition for cold preservation include those satisfying one or more of the following conditions (i) to (iii).
(I) before and after the freeze, as the L ^* a ^* b ^* color system of a ^* is, from a positive value to a negative value, or that varies from a negative value to a positive value. That is, the ^{a *} a1 ^* of cold composition after freezing, if the ^{a *} of cold composition before freezing was ^{a2 *, a1 * <0 <} a2 *, or ^{a2 *} <0 <a1 * of Something that satisfies the relationship.
(Ii) before and after freezing, those L ^* a ^* b ^* color system of b ^* is, from a positive value to a negative value, or that varies from a negative value to a positive value. That, ^{b *} and b1 ^* of cold composition after freezing, if the ^{b *} of the cold composition before freezing was ^{b2 *, b1 * <0 <} b2 *, or ^{b2 *} <0 <b1 * of Something that satisfies the relationship.
(Iii) The difference obtained by subtracting a ^* before freezing from a ^* after freezing is 10 or more (+10 or more). That is, ^{a *} of cold composition after freeze-a1 ^*, if the ^{a *} of cold composition before freezing was a2 ^*, satisfy the relationship a1 ^* -a2 * ≧ 10.
However, a1 ^* and b1 ^* are values at the same time, and a2 ^* and b2 ^* are values at the same time.
The composition for cold preservation changes color more greatly before and after freezing by satisfying one or more (one, two or all) of the above (i), (ii) and (iii).

As the composition for cold preservation, in the above-mentioned composition, “the pH (A) and the pH (B) are lower than the color change range of the pH indicator, the pH of the color change range, and the pH higher than the color change range. When the pH of the composition for cold preservation before freezing is defined as pH (C) instead of the condition of “showing values in different pH ranges among the pH ranges”, “pH (C) and pH (B) are It is also preferable to satisfy the condition of “showing values in different pH ranges among the three pH ranges of pH lower than the color change range of the pH indicator, pH of the color change range, and pH higher than the color change range”. That is, preferable examples of the cold-retaining composition include those satisfying the following condition (vi).
(Vi) pH (pH (A)) in the case where all the components other than the precipitation component and water (the non-deposition component, the pH indicator, and other components) are replaced with the same mass of water is 7.0 or more. 11.5 or less, and the pH (pH (B)) when all the components other than the non-precipitating component and water (the precipitating component, the pH indicator, and other components) are replaced with the same mass of water. 2.7 or more and 9.0 or less, and the pH (pH (C)) and pH (B) of the composition for cold preservation before freezing is lower than the discoloration range of the pH indicator, the discoloration Among the three pH ranges, the pH of the range and the pH higher than the discoloration range, values that are different from each other in the pH range.
The pH (C) is preferably a pH at a temperature at which the pH indicator is dissolved in the composition for cold preservation.

When the composition for cold preservation satisfies the condition (vi), the color changes more greatly before and after freezing.
The composition for cold preservation that satisfies the condition (vi) is a combination of the precipitation component and the non-precipitation component that affect the color development of the pH indicator, in which the pH of an aqueous solution having a predetermined concentration is within a specific range. By combining a pH indicator having a suitable color change range with the precipitated component and the non-precipitated component, the color change depending on the color change or the presence or absence of the pH indicator is remarkably increased.

The composition for cold preservation has a color difference (ΔE) before and after freezing of 8 or more, more preferably 10 or more, and particularly preferably 11 or more.
Further, the upper limit value of the color difference (ΔE) before and after freezing of the composition for cold preservation is not particularly limited, but may be 50, 48, or 46, for example.

  In the pre-freezing composition, either the protonation or deprotonation of the pH indicator is affected by the precipitation component dissolved in the cold-preserving composition in the stage before freezing. At a later stage, most or all of the precipitation components are precipitated in the cold-retaining composition, so that either protonation or deprotonation in the pH indicator is not affected by the precipitation components at all. It is speculated that it is only received mildly. As a result, it is presumed that the cold-retaining composition largely changes in color before and after freezing, reflecting the change in color presence or absence of the pH indicator.

The composition for cold preservation is obtained by blending water, the precipitation component, the non-precipitation component, the pH indicator, and, if necessary, the other components.
The blending method of each component is not particularly limited, and can be arbitrarily adjusted so that each component is uniformly dissolved or dispersed at a temperature higher than the freezing temperature of the composition for cold preservation.
For example, when blending each component, all the components may be added and then mixed, or some components may be mixed while being added sequentially, and all components may be mixed while being added sequentially. May be.
The mixing method is not particularly limited, a method of mixing by rotating a stirrer or a stirring blade; a method of mixing using a mixer, a three-roller, a kneader, a bead mill or the like; a method of mixing by adding ultrasonic waves, etc. What is necessary is just to select suitably from a well-known method.

The cold-retaining tool according to the present invention includes the cold-retaining composition, and is configured, for example, by holding the cold-retaining composition by holding means such as a container that can enclose a liquid material.
The material of the holding means is not particularly limited as long as it is transparent to the extent that the color change (discoloration) of the held cooling composition can be visually recognized. Preferred examples include polyethylene and polypropylene. Examples thereof include synthetic resins such as polyolefins, polyamides, and polyesters. Among these, polyolefin is preferable from the viewpoint of excellent low-temperature brittleness resistance, water resistance, chemical resistance, and the like, and high-density polyethylene that is easy to mold and has high strength is more preferable.

Since the color-retaining composition largely changes in color before and after freezing, the presence or absence of freezing can be easily visually confirmed. And this color change of the composition for cold insulation can be visually recognized from the outside of the cold insulator, and thereby, it can be easily visually confirmed whether or not the cold insulator is sufficiently cooled to a desired temperature. ing.
In addition, since the effect of the cold-retaining composition is not impaired even if cooling and heating are repeated, such as repeated freezing and thawing, the cold-retaining tool provided with the composition is suitable for repeated use. is there.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples. In the following, the unit “ppm” of the content (blending amount, concentration) of the pH indicator is based on the mass ratio.

The raw materials used in the examples and comparative examples are shown below.
(Thickener)
Acrylic polymer (1): “Aronbis AH-305X” manufactured by Toa Gosei Co., Ltd.
Acrylic polymer (2): “Apecku HV-505ED” manufactured by Sumitomo Seika Co., Ltd.
-Acrylic polymer (3): “AQUALIC AS58” manufactured by Nippon Shokubai Co., Ltd.
Acrylic polymer (4): “AQUALIC FH-S” manufactured by Nippon Shokubai Co., Ltd.
Acrylic polymer (5): “AQUALIC IH-G” manufactured by Nippon Shokubai Co., Ltd.
Acrylic polymer (6): “Junron PW121” manufactured by Toa Gosei Co., Ltd.
・ CMC: Carboxymethylcellulose (manufactured by Kanto Chemical Co., Inc.)
-XTG: Xanthan gum (manufactured by Sankisha)
(PH indicator)
・ BTB: Bromthymol Blue (manufactured by Wako Pure Chemical Industries, Ltd.)
・ BCP: Bromocresol purple (Wako Pure Chemical Industries, Ltd.)
・ PR: Phenol red (manufactured by Wako Pure Chemical Industries)
・ TP: Thymolphthalein (Wako Pure Chemical Industries)
・ BPB: Bromophenol blue (manufactured by Wako Pure Chemical Industries, Ltd.)

[Example 1]
<Manufacture of composition for cold preservation and cold insulation tool>
At room temperature (20-25 ° C.), water (96.7 parts by mass), BTB, acrylic polymer (1) (1.3 parts by mass), dipotassium hydrogen phosphate (2 parts by mass) were added and mixed. A composition for cold preservation was obtained. At this time, the amount of BTB was adjusted so that the content of the obtained composition for cold insulation was 10 ppm. Table 2 shows the components and concentrations other than water, pH (A), pH (B), and the like. And pH (C) of the obtained composition for cold preservation was measured. The results are shown in Table 6. The pH (A), pH (B), and pH (C) were all measured with the temperature of the measurement object being 25 ° C.
In Table 2, the concentration described in “% by mass” in the column of pH (A) indicates the concentration of the aqueous inorganic salt solution at the time of pH (A) measurement. Similarly, the concentration described in the unit of “mass%” in the column of pH (B) indicates the concentration of the thickener aqueous solution at the time of pH (B) measurement. The “color change” described in the column of the color change region of the pH indicator means that the pH indicator changes when the pH of the liquid containing the pH indicator changes from a specific value to a higher value. Indicates a color change in the color change range. For example, “yellow → blue” indicates that the pH indicator changes the color of the liquid from yellow to blue in the process of increasing the pH of the liquid.
Next, the obtained composition for cold insulation was sealed in a high-density polyethylene container to obtain a cold insulation tool.

<Evaluation of composition for cold preservation>
(Color difference (ΔE))
The obtained composition for cold insulation (cold insulation tool) was cooled to -25 ° C. During this time, the composition for cold preservation was frozen at a temperature higher than −25 ° C. and changed in color before and after freezing. And about the composition for cold preservation before freezing and the composition for cold preservation after freezing, using a color difference measuring device ("X-rite 530" manufactured by X-Rite Co., Ltd.), L ^* , a ^* , b under the following conditions: ^{* Was} measured.
(Measurement condition)
About the composition for cold preservation enclosed with the container made from a high density polyethylene, the color difference measuring device was applied from the top of this container, and the value of L ^* , a ^* , b ^* before freezing was measured. Further, the composition for cold preservation was frozen in a freezer at −25 ° C., and the values of L ^* , a ^* , b ^* immediately after freezing were measured in the same manner as before the freezing.

Then, from the measured values of L ^* , a ^* and b ^* obtained, the color difference (ΔE) of the composition for cold preservation before and after freezing was calculated according to the following formula (I). The results are shown in Table 4.
(Calculation of color difference (ΔE))
^{ΔE = [(L1 * -L2 *} ) 2 + (a1 * -a2 *) 2 + (b1 * -b2 *) 2] 1/2 ···· (I)
(In the formula, L1 ^* is the value of L ^* of the composition for cold preservation after freezing, L2 ^* is the value of L ^* of the composition for cold preservation before freezing, and a1 ^* is the composition for cold preservation after freezing. of a ^* is a value, a2 ^* is the value of a ^* of cold composition before freezing, b1 ^* is the value of b ^* of cold composition after freezing, b2 ^* before freezing (B ^* value of the composition for cold preservation, L1 ^* , a1 ^* and b1 ^* are values at the same time, and L2 ^* , a2 ^* and b2 ^* are values at the same time.)

(Color change)
When ΔE was calculated, the color change of the composition for cold preservation before and after freezing was visually evaluated according to the following criteria. The results are shown in Table 4.
In Table 4, “color change” described in the column of the evaluation result indicates a color change of the composition for cold preservation before and after freezing. For example, “green → yellow” means a composition for cold preservation. Indicates that the color was green before freezing and yellow after freezing.
○: The color change before and after freezing is large and the cooling state is very easy to visually recognize.
(Triangle | delta): The color change before and behind freezing can be discriminate | determined and the visual recognition of a cooling state is possible.
X: The color change before and after freezing is unclear, and it is difficult or impossible to visually recognize the cooling state.

<Manufacture of composition for cold preservation and cold insulation, evaluation of composition for cold insulation>
[Examples 2 to 6, Reference Example 1, Comparative Examples 1 to 4]
A composition for cold insulation and a cold insulation tool were produced in the same manner as in Example 1 except that the composition components and concentrations of the cold insulation composition were as shown in Table 2, and the cold insulation composition was evaluated. The results are shown in Table 4. Further, Table 6 shows the pH (C) of the composition for cold preservation.

[Examples 7 to 12, Reference Examples 2 to 5, Comparative Examples 5 to 10]
A composition for cold insulation and a cold insulation tool were produced in the same manner as in Example 1 except that the composition components and concentrations of the cold insulation composition were as shown in Table 3, and the cold insulation composition was evaluated. In addition, evaluation of the composition for cold preservation was performed only about the color change by visual observation. The results are shown in Table 5. Further, Table 6 shows the pH (C) of the composition for cold preservation.

In each of the compositions for cold insulation of Examples 1 to 12, Reference Examples 1 to 5, and Comparative Examples 1 to 10, the inorganic salt was completely dissolved before freezing. The whole amount was precipitated.
In all of Examples 1 to 12, Reference Examples 1 to 5, and Comparative Examples 1 to 10, the content of the pH indicator in the composition for cold preservation was 10 ppm.

As is clear from the above results, in Examples 1 to 12, the color of the composition for cold preservation clearly changes with the precipitation of the inorganic salt during freezing, reflecting the change in color development of the pH indicator, and the cooling state Was easily visible. Reference Examples 1-5 were the same.
On the other hand, in Comparative Examples 1 to 10, even if the inorganic salt precipitated during freezing, the color change of the composition for cold preservation was unclear, and it was difficult or impossible to visually recognize the cooling state. .

<Manufacture of composition for cold preservation and cold insulation, evaluation of composition for cold insulation>
[Examples 13 to 25]
A composition for cold insulation and a cold insulation tool were produced in the same manner as in Example 1 except that the composition components and concentrations of the cold insulation composition were as shown in Tables 7 to 8, and the cold insulation composition was evaluated. In addition, evaluation of the composition for cold preservation was performed only about the color change by visual observation. The results are shown in Table 9. Table 9 also shows the pH (C) of the cold-retaining composition.
For example, in Example 13, three kinds of potassium sulfate, sodium sulfate, and diammonium hydrogen phosphate are used in combination as inorganic salts, but the content in these cold-retaining compositions and pH (A) measurement time The concentration in the aqueous solution is 5% by mass for potassium sulfate, 3% by mass for sodium sulfate, and 2% by mass for diammonium hydrogen phosphate. Moreover, in Example 13, pH (B) was 3.5 and pH (C) was 6.4.

In all of the compositions for cold storage of Examples 13 to 25, the inorganic salt was completely dissolved before freezing, but after the freezing, all or almost all of the inorganic salt was precipitated.
In all of Examples 13 to 25, the content of the pH indicator in the composition for cold preservation was 10 ppm.

  As is apparent from the above results, in Examples 17 to 29, the color of the composition for cold preservation clearly changed with the precipitation of the inorganic salt during freezing, reflecting the change in color of the pH indicator, and the cooling state Was easily visible.

  The present invention can be used as a cold insulator for various fresh products.

Claims (2)

A cold insulation device comprising a cold insulation composition containing water, a precipitation component, a non-precipitation component and a pH indicator,
The precipitation component is a component that does not fall under the pH indicator when it is frozen when the composition for cold preservation is frozen.
The non-precipitated component is a component that does not precipitate when the composition for cold preservation is frozen and does not correspond to the pH indicator,
The composition for cold preservation has a pH (A) of 7.0 or more and 11.5 or less when all the components other than the precipitated component and water are replaced with water, and the non-precipitated component and the content other than water are contained. PH (B) when all the components are replaced with water is 2.7 or more and 9.0 or less,
pH (A) and pH (B) show values in different pH ranges among the three pH ranges of pH lower than the color change range of the pH indicator, pH of the color change range, and pH higher than the color change range. A cold insulator characterized by that.   The cold insulator according to claim 1, wherein the precipitation component is an inorganic salt, and the non-deposition component is a thickener.