JPS584955B2 - Temperature indicating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature-indicating composition that reversibly changes color at a specific temperature.

More specifically, the present invention relates to a novel temperature-indicating composition that utilizes the Kraft point of an ionic surfactant to cause a reversible color change of a dye.

Until now, materials that indicate a specific temperature by changing color include temperature-indicating paints and liquid crystals, but since these require the use of special compounds, they are expensive and difficult to determine. It was not something that could be easily used in such places.

The inventors of the present invention have conducted extensive research to develop a temperature-indicating material that can sensitively sense temperature changes using easily available materials. Focusing on the fact that it has the property of increasing
The present invention has been accomplished.

It is known that when a suspension containing an ionic surfactant at a critical micelle concentration or higher reaches a specific temperature called the Krafft point, its solubility increases rapidly and it becomes a homogeneous and transparent liquid.

This rapid increase in solubility at temperatures above the raft point is thought to be due to the solid fine particles of the ionic surfactant in the liquid melting when they reach the craft point.

The figure graphically depicts the temperature dependence of solubility for several surfactants.

In the present invention, when the ionic surfactant rapidly dissolves at this Kraft point and forms micelles in the liquid, if a micelle-affinity dye is present, this and the micelles combine to cause a color change and a phosphorescence effect. The present invention provides a temperature-indicating material that utilizes the phenomenon of light generation.

Here, micelle-affinity dyes refer to oil-soluble dyes that can easily penetrate and be compatible with the lipophilic group inside the micelles, and ionic dyes that can electrically bond to the ionic group on the surface of the micelles. means.

The composition of the present invention comprises an ionic surfactant suspension containing at least a critical micelle concentration of an ionic surfactant to which is added an effective amount of a coloring micelle-compatible dye.

The ionic surfactant used in the present invention may be any one that forms ions when dissolved in a medium, including anionic surfactants, cationic surfactants, and amphoteric surfactants. Any agent may be used.

When used, an appropriate one is selected from those having a Kraft point corresponding to the temperature to be measured.

Examples of such ionic surfactants are shown in Table 1 along with their Kraft points.

These ionic surfactants are suspended in a given solvent at a concentration greater than their critical micelle concentration.

There is no particular upper limit to this concentration, but it is preferable that the concentration is at most such that it does not separate into two phases when left standing.

Usually, a range of 0.1 wt% to 30 wt% is used.

Next, water is used as a medium in which these ionic surfactants are suspended.

Further, as the dye added to the ionic surfactant suspension, a micelle-affinity dye is used.

The micelle-compatible dyes include oil-soluble dyes that are compatible with the lipophilic group moieties of the micelles, or ionic dyes that are electrically adsorbed on the surface of the micelles, such as vinacyatur chloride, rhodamine G1 eosin, and fluorescein. , 8-
Examples include anilino-1-naphthalenesulfonic acid (Mg).

These dyes are added in an amount sufficient to color the suspension, for example at a concentration of 10@-5 mol/l, but a larger amount can be added if desired.

The composition of the present invention changes from a liquid phase to a cloudy state to a transparent state at the Kraft point of the ionic surfactant therein, and the dissolved ionic surfactant forms micelles, and has micelle affinity. Since the sex pigment combines with the micelles and causes a bright color change, the predetermined temperature can be easily determined by visual observation.

Furthermore, by adding an appropriate salt to the composition of the present invention, the indicated temperature can be shifted by about 1 to 15°C from the Krafft point of the ionic surfactant, and the rise of the solubility curve at the Kraft point can be suppressed. Can be sharpened.

Therefore, by utilizing this, the indicated temperature can be finely adjusted and the reaction sensitivity can be increased.

In this case, the salt used is preferably a salt containing the same type of ion as the ion that neutralizes the hydrophilic group in the ionic surfactant.

In other words, in the case of higher fatty acid sodium and higher aliphatic sodium sulfonate.

When sodium chloride, sodium sulfate, etc. are higher alkyl magnesium sulfate, magnesium chloride, magnesium sulfate, etc. are used.

This salt is added in an amount ranging from approximately equimolar to several times the molar amount of the ionic surfactant, and the movement of the indicated temperature can be controlled by increasing or decreasing the amount added.

The temperature-indicating composition of the present invention can be easily prepared using readily available and inexpensive materials as raw materials, and can acutely sense a predetermined temperature by observation with the naked eye. It has the advantage of being easy to use even in places where it cannot be used, so it can be widely used as a temperature measurement and temperature control sign.

Also, the color change according to the invention is reversible.

In response to temperature changes in the direction of temperature increase, the color usually changes within 1 to 10 seconds when the designated temperature is reached.

This does not depend on the combination of types of surfactant dyes.

On the other hand, when the cooling direction changes, supercooling may occur, and in that case, color change is delayed.

However, when the temperature is cooled to 10° C. or less below the indicated temperature or supercooling does not occur, the original color usually returns within several seconds to several minutes.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Add C1C13H37OCH2C0ONa to 1 ml of distilled water.
5 and stir well to form a suspension, then add 0.02 m9 of binaciatool chloride and mix thoroughly.

The reddish-purple suspension thus prepared was sealed in a glass ampoule, immersed in a water bath, and gradually heated at a rate of 0.2°C/min. , the deep color was observed to change rapidly from reddish-purple to blue.

Therefore, by observing this color change, it was possible to easily measure the temperature at 60°C.

Moreover, when the temperature was cooled to room temperature, the color returned to reddish-purple in 30 seconds.

Example 2 10 m9 of C16H33N(CH3)3Br and 1 part of distilled water
Stir well to make a suspension, add 0.02 ml of fluorescein, and mix thoroughly.

The yellow suspension thus prepared was sealed in a glass ampoule, immersed in a water bath, and slowly heated at a rate of 0.2°C/min. It was observed that the deep color changed vividly from yellow to blue-green fluorescent color.

Therefore, by observing this color change, the temperature 2
Measurement at 1°C could be easily carried out.

Further, when the temperature was lowered to 10° C. or lower, it turned yellow in about 3 minutes.

Example 3 107 mg of C14H2,5o41/2Ca was added to distilled water,
The mixture was added to 1 ml of each of a 0.05 M CaCl 2 aqueous solution, a 0.1 M CaCl 2 aqueous solution, and a 1 M CaCl 2 aqueous solution and stirred well to obtain a suspension.

Add 0.02 mg of binaciatool chloride to each suspension and mix thoroughly.

The reddish-purple suspension thus prepared was sealed in a glass ampoule, immersed in a water bath, and gradually heated at a rate of 0.2°C/min. 74
At temperatures of 76.5-77°C and 87-87.5°C, the deep color was observed to rapidly change from reddish-purple to blue.

In this way, C14H2C14H2/2Ca and CaC
71℃, 73℃, 76.5℃,
A temperature of 87° C. could be easily measured.

Similar to Example 1, the color change was reversible.

Example 4 10 m9 of dipalmitoyl phosphatidylcholine and 1 ml of distilled water are thoroughly stirred to form a suspension, and 0.02 ml of binacyatul chloride is added and thoroughly mixed.

The reddish-purple suspension thus prepared was sealed in a glass ampoule, immersed in a water bath, and gradually heated at a rate of 0.2°C/min. The color reduction was observed to change rapidly from reddish-purple to blue.

By observing this color change, the temperature of 41° C. could be easily determined.

Similar to Example 1, the color change was reversible.

[Brief explanation of the drawing]

The figure is a graph showing the relationship between temperature and solubility for three types of ionic surfactants.

Claims (1)

[Scope of Claims] 1. A temperature-indicating composition comprising adding a micelle-affinity dye to an aqueous suspension of an ionic surfactant containing an ionic surfactant having at least a critical micelle concentration. 2. A temperature-indicating composition prepared by adding a salt and a micelle-affinity dye to an ionic surfactant aqueous suspension containing at least a critical micelle concentration of an ionic surfactant.