JP2006045464A - Coolant containing reversibly temperature-indicating agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coolant capable of estimating, by change of color, its cooled state in cooling in a refrigerator or a freezer and remaining cooling capacity of the coolant in use. <P>SOLUTION: The coolant comprises a gel coolant 11 having transparency and a plurality of microcapsules 12 containing a reversibly temperature-indicating agent, wherein the microcapsules 12 are dispersed in the coolant 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling agent capable of judging a cooling state when a cooling agent is cooled in a refrigerator or a freezer and a remaining cooling capacity during use of the cooling agent based on a change in color.

  As a method for easily grasping the temperature state of the cryogen, there has been proposed a cryogen to which an organic reversible thermostat in which the cryogen is microencapsulated is added (for example, see Patent Document 1).

FIG. 3 is a schematic view showing a component structure of a conventional cryogen added with a microencapsulated organic reversible thermostat.
In the cold-reserving agent 30 shown in FIG. 3, the organic reversible temperature-indicating pigment 31 microencapsulated in the cold-reserving agent 30 is dispersed. Can be detected by. Here, the organic reversible temperature indicating pigment means an organic reversible temperature indicating agent.

  The organic reversible temperature indicating pigment 31 includes a predetermined amount of a leuco dye, a phenol compound such as bisphenol that acts as a developer, and an alcohol compound that controls the melting point to set the temperature indicating region of the organic reversible temperature indicating pigment. It is a blended chromogen and is contained in microcapsules.

The microcapsule is produced using a commercially available aqueous capsule slurry or capsule powder obtained by drying the slurry using a spray dryer.
The amount of the organic reversible thermochromic pigment to be added to the cryogen is 0.3 parts to 3.0 parts of the organic reversible thermochromic pigment that develops a black color at a temperature of, for example, -25 ° C. or less. It is described that a cold storage agent that mixes and uniformly disperses the components and can sense the degree of cold storage by colorimetry.
JP 2002-129153 A

  However, the conventional microencapsulated organic reversible thermochromic pigment-containing cryogen has been described in terms of the amount of organic reversible thermochromic pigment added to the cryogen and the material of the microcapsule. Is not disclosed.

  Accordingly, an object of the present invention is to provide a reversible thermostat-containing cryogen in which the particle size of the reversible thermostat-containing microcapsules is optimized and these microcapsules are dispersed in the cryogen.

  In order to solve such a problem, the reversible thermostat-containing cryogen according to the present invention is a reversible gel comprising a transparent gel-like cryogen and a plurality of microcapsules containing the reversible thermostat. A cryostat containing a temperature indicating agent, wherein the microcapsules are dispersed in the cryogen, and the microcapsules have a particle size of 1 μm or more and 100 μm or less.

  In the microcapsules having such a configuration, when the particle diameter is smaller than 1 μm, the color tone change is not known, and when the particle diameter is larger than 100 μm, the microcapsules are easily cracked when mixed in the cooling agent. 100 μm or less is desirable. In addition, the size of the microcapsules is not limited to one type, and it is easy to disperse if the microcapsules of various sizes are mixed in the cryogen with a particle size ranging from 1 μm to 100 μm. In addition, it is preferable because visibility is improved. Since a plurality of microcapsules containing reversible thermostats are three-dimensionally dispersed in the cryogen, they are not restricted in the viewing direction, that is, from various directions without requiring directivity. The temperature state of the cooling agent can be grasped.

  In order to solve such a problem, the reversible thermostat-containing cryogen according to the present invention is a reversible gel comprising a transparent gel-like cryogen and a plurality of microcapsules containing the reversible thermostat. A thermostat containing a thermostat, wherein the microcapsules are dispersed in the cryogen, and as the reversible thermostat, a plurality of types of compositions having different colors are used, and the microcapsules are used for each microcapsule. And a reversible thermostat comprising the respective compositions.

  As a result, the microcapsules are dispersed in the cryogen, and each different microcapsule contains a different reversible thermostat, so not only one level of temperature but also multiple different levels of temperature are displayed. can do. Further, by adopting this configuration, for example, it becomes possible to grasp the rate of the temperature change of the cooling agent from the temperature difference and the time difference of the transition from one temperature to another temperature.

  The microcapsules have a particle size of 1 μm or more and 100 μm or less.

  In such a configuration, if the microcapsule is smaller than 1 μm, the change in color tone is not known. If the microcapsule is larger than 100 μm, the microcapsule is liable to break when mixed in the cooling agent. In addition, the size of the microcapsules is not limited to one type, and it is easy to disperse if the microcapsules of various sizes are mixed in the cryogen with a particle size ranging from 1 μm to 100 μm. In addition, it is preferable because visibility is improved.

  The reversible thermostat-containing cryogen according to the present invention is characterized in that the microcapsule is contained in the cryogen in an amount of 1% by volume to 50% by volume.

  If the proportion of microcapsules in the cryogen is less than 1% by volume, it is difficult to confirm a change in color, and if the proportion of microcapsules in the cryogen exceeds 50% by volume, the performance of the cryogen decreases. Therefore, the ratio of the microcapsules to be blended in the cryogen is preferably 1% by volume or more and 50% by volume or less.

  As described above, the reversible thermostat-containing cryogen of the present invention has microcapsules containing the reversible thermostat dispersed in the cryogen, and the particle size of the microcapsules is 1 μm or more and 100 μm or less. Therefore, the dispersion of the microcapsules in the cryogen is improved, and the temperature of the cryogen itself can be accurately grasped. In addition, since a plurality of types of reversible thermostats having different temperatures at which the color changes are stored for each microcapsule, not only one level of temperature but also a plurality of levels of temperature can be grasped by a plurality of color changes. .

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this embodiment is specifically described in order to better understand the gist of the invention, and does not limit the present invention.

FIG. 1 is a cross-sectional view showing an example of a first embodiment of a reversible thermostat-containing cryogen according to the present invention.
In the reversible thermostat-containing cryogen 10 shown in FIG. 1, microcapsules 12 are three-dimensionally dispersed in a cryogen 11. The particle size of the microcapsule 12 is 1 μm or more and 100 μm or less, and is composed of a plurality of particle sizes.

  The reversible thermostat used in the present invention is composed of three components: an electron donating color-forming organic compound, an electron accepting compound, and a polar organic compound. This electron-donating color-forming organic compound has a role of determining color, and examples thereof include 3,6-dimethoxyfluorane (yellow), 3-cyclohexylamino-6-chlorofluoride. Oran (orange), 3-diethylamino-6-methyl-7-chlorofluorane (red), 3-diethylaminobenzfluorane (peach), rhodamine B lactam (red), crystal violet lactone (blue), 3-diethylamino- Examples include 7-dibenzylaminofluorane (green), 3-diethylamino-6-methyl-7-anilinofluorane (black), and the like.

  The electron-accepting compound has a role of determining the color density. As such, bisphenol A, propyl gallate, or the like is usually used.

  Furthermore, the polar organic compound has a role of determining the color change temperature. Examples of such a polar organic compound include linear higher alcohols having 12 to 20 carbon atoms and esters thereof. Specific examples include higher alcohols such as n-octyl alcohol, n-decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, eicosanol, 1,8-octanediol, 1,10-decanediol, and esters thereof. It is done. The discoloration temperature can be arbitrarily selected within the range of about -40 to 50 ° C. by appropriately mixing these alcohols and esters thereof.

  The reversible thermostat used in the present invention is prepared by appropriately selecting the above three components of the electron donating color-forming organic compound, the electron accepting compound and the polar organic compound. However, reversible thermostats composed of these three components are commercially available, and commercially available products can also be used in the present invention.

  Commercially available reversible thermostats include, for example, medecyl color (trade name; manufactured by NOF Giken Co., Ltd.), metamocolor (trade name; manufactured by Pilot Ink Co., Ltd.), ST color (trade name; Kuboi Ink). Etc.).

  When paraffin wax and / or microcrystalline wax is blended with a reversible thermostat and used as a core substance, microcapsules 12 with a reversible thermostat are obtained.

  The method for producing the microcapsules 12 containing the reversible thermostat is not particularly limited, and is a method commonly used in the production of conventional microcapsules, for example, interfacial polymerization method, in situ method, coacervation method, A curing coating method (orifice method), a submerged drying method, a spray / granulation method, and the like can be used, but an in situ method is preferably used.

  The paraffin wax or microcrystalline wax itself used in the present invention is not particularly limited. Usually, these are commercially available as mixed products having a plurality of carbon number distributions, and commercially available products can be used in the present invention.

  The blending amount of the paraffin wax and microcrystalline wax used in the present invention is not particularly limited. Usually, the paraffin wax and / or microcrystalline wax is 0.2 to 10 parts by weight with respect to 100 parts by weight of the reversible thermostat. It is preferable to mix | blend in a ratio. If the amount is less than 0.2 parts by weight, the difference between the melting point of the reversible thermostat contained in the microcapsule 12 and the freezing point may not be reduced, and if the amount exceeds 10 parts by weight, the melting point of the reversible thermostat contained in the microcapsule 12 The difference between the freezing point and the freezing point is not reduced to a certain extent, which is uneconomical.

  The particle size of the microcapsule 12 containing the reversible thermostat is controlled by the number of rotations and the stirring time (emulsification time) when the reversible thermostat is mixed with paraffin wax and / or microcrystalline wax. Can do.

  The particle size of the microcapsule 12 is preferably in the range of 1 μm to 100 μm, more preferably in the range of 2 μm to 10 μm.

  This is because, when the particle size of the microcapsule 12 is smaller than 1 μm, the visibility of the color change when the cryogen 11 containing the microcapsule is cooled is lowered, and the particle size of the microcapsule 12 is larger than 100 μm. This is because, when the microcapsule 12 is blended with the cooling agent 11, the microcapsule 12 is easily broken. In order to further improve the visibility of the microcapsule 12 and make the microcapsule 12 more difficult to break, the particle size of the microcapsule 12 is more preferably in the range of 2 μm to 10 μm.

  The ratio (mixing amount (volume%)) of the microcapsules 12 in the cooling agent 11 is desirably 1 volume% to 50 volume%. The reason for this is that when the blending amount of the microcapsules 12 is less than 1% by volume, the visibility of the color change when the cold-retaining agent 11 blended with the microcapsules 12 is cooled is lowered, and the blending amount of the microcapsules 12 is 50. This is because, if the volume% is exceeded, the cooling performance of the cooling agent 11 is lowered.

The cooling agent 11 is not particularly limited as long as it is transparent.
For example, an ice pack (manufactured by Iwata Ice Refrigeration Co., Ltd.), a freezing point (trade name, manufactured by Kamoi Processed Paper Co., Ltd.) and the like are preferably used.

(Experimental example 1)
In order to examine the particle size of the microcapsule 12 containing the reversible thermostat, the following experiment was conducted.

  First, a sodium salt of a styrene maleic anhydride copolymer prepared by dissolving a styrene maleic anhydride copolymer (trade name: Scripset-520 / manufactured by Monsanto) together with a small amount of sodium hydroxide to 5 wt%, pH 4.3. An aqueous mixture of 200 parts of the above reversible thermostat and 2 parts of paraffin wax (trade name: NHP-10 / Nippon Seiwa Co., Ltd.) having a melting point of 75 ° C. is emulsified and dispersed. An emulsion was obtained.

  Next, 20 parts of melamine was added to 51.5 parts of 37% formaldehyde aqueous solution to the dispersion of this dispersion, adjusted to pH 9.5 with a small amount of sodium hydroxide aqueous solution, and heated and dissolved to 80 ° C. in 15 minutes. Then, the mixture is kept warm for 2 hours and then cooled to prepare the reversible thermostat microcapsule dispersion of the present invention. Finally, the microcapsule dispersion thus obtained is subjected to a known drying method such as spray drying. By drying by a method or the like, microcapsules 12 having particle diameters of 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 15 μm, 100 μm, and 150 μm were obtained.

  The amount of the microcapsules 12 in the cryogen 11 is fixed at 25% by volume, and the microcapsules 12 having particle diameters of 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 15 μm, 100 μm, and 150 μm are placed in the cryogen 11. The samples 11 to 18 were prepared by blending. Next, with respect to Samples 11 to 18, the presence or absence of cracking of the microcapsule 12 and the visibility when the cold-reserving agent 11 containing the microcapsule was cooled (identity of color change) were evaluated.

  The evaluation criteria regarding the occurrence of cracking of the microcapsule 12 when the microcapsule 12 is blended with the cold-retaining agent 11 are ○ when the crack does not occur, and Δ when the case where the microcapsule 12 is cracked can be used. The case where it was easy to break and could not be used was marked as x.

  On the other hand, the evaluation criteria of visibility are ○ when the visibility (color tone change distinguishability) is good when the cooling agent 11 containing the microcapsule 12 is cooled, Δ when the visibility is slightly inferior, When it was inferior, it was set as x.

  As a comprehensive evaluation, there is no cracking of the microcapsule 12 when the microcapsule 12 is blended with the cold insulation agent 11, and visibility when the cold insulation agent 11 blended with the microcapsule 12 is cooled (identity of color change). The case where it is good is marked with ◯, and the case where the visibility is slightly inferior or some of the microcapsules 12 are broken but can be used is marked with △. And when mix | blending the microcapsule 12 with the cold insulating agent 11, there are many cracks of the microcapsule 12, and when visibility cannot be used when the cold insulating agent 11 which mix | blended the microcapsule 12 is cooled, it is used The case where it was not possible to withstand was marked as x. The evaluation results are shown in Table 1.

  From Table 1, when the particle size of the microcapsule 12 is smaller than 1 μm (for example, 0.5 μm), the visibility is inferior. When the particle size is larger than 100 μm (for example, 150 μm), the microcapsule 12 has good visibility. Therefore, it was found that the particle size of the microcapsule 12 is preferably 1 μm or more and 10 μm or less. Moreover, in order to further improve the visibility of the microcapsule 12 and further suppress the occurrence of cracks, it was found that the particle size of the microcapsule 12 is more preferably 2 μm or more and 10 μm or less.

(Experimental example 2)
Next, in order to examine the blending amount (volume%) of the microcapsule 12 in the cryogen, the following experiment was performed.

  Using the microcapsules 12 having a particle size of 10 μm, the blending amount of the microcapsules 12 in the cold-reserving agent 11 is 0.5% by volume, 1% by volume, 25% by volume, 50% by volume, 60% by volume, and 80% by volume. Samples 21 to 26 were prepared. About these samples 21-26, the visibility (distinguishability of a color tone change) when the cooling agent 11 which mix | blended the microcapsule 12 was cooled and the cooling performance of the cooling agent 11 were evaluated.

  Evaluation criteria are ○ when the visibility (color tone change distinguishability) when cooling the cold-reserving agent 11 containing the microcapsules 12 is good, Δ when the visibility is slightly inferior, and × when the visibility is inferior. did. On the other hand, the case where the cold-retaining performance of the cold-retaining agent 11 was good was evaluated as ◯, the case where the cold-retaining performance was slightly inferior, and the case where the cold-retaining performance was inferior as x.

  Visibility (identity of color change) when cooling the cold-insulating agent 12 containing the microcapsules 12 and the cold-retaining performance of the cryogen 12 are comprehensively evaluated. Or, although the cold insulation performance is slightly inferior, the case where it can be used is marked with Δ, and the case where the visibility or the cold insulation performance is poor and cannot be used is marked with x. The evaluation results are shown in Table 2.

  From Table 2, when the compounding amount (volume%) of the microcapsule 12 is less than 1% by volume (for example, 0.5% by volume), the visibility is poor, and when the compounding amount exceeds 50% by volume, For example, in the case of 60% by volume, the cold insulation performance is slightly inferior, and in the case of 80% by volume, the cold insulation performance is inferior, so it was found that the blending amount of the microcapsules 12 is preferably 1% by volume or more and 50% by volume or less.

FIG. 2 is a cross-sectional view showing an example of the second embodiment of the reversible thermostat-containing cryogen of the present invention.
In the reversible thermostat 20 containing reversible thermostat shown in FIG. 2, a plurality of microcapsules 22 (22a, 22b, 22c) containing reversible thermostats having different temperatures at which the color changes are dispersed in the cryogen 21. ing. Note that the microcapsules 22a, 22b, and 22c represent microcapsules each containing one type of different reversible thermostat.

  As in the first embodiment, the reversible thermostat is a composition composed of three components of an electron-donating color-forming organic compound, an electron-accepting compound, and a polar organic compound, and the three components are appropriately selected. Thus, the color and the temperature at which the color changes are determined. A plurality of commercially available reversible thermostats can also be used.

  The cooling agent 21 is not particularly limited as long as it is transparent. Moreover, a commercially available thing can be used similarly to 1st embodiment.

  In the same way as in the first embodiment, the microcapsulation of the reversible thermostat is carried out by blending the reversible thermostat with paraffin wax and / or microcrystalline wax and using it as a core substance, so that Capsule 22 is obtained. By adapting to a plurality of types of reversible thermostats, microcapsules 22a, 22b, and 22c having different reversible thermostats stored therein can be obtained for each microcapsule 22a, 22b, and 22c.

  As in the first embodiment, the particle size of the microcapsule 22 containing the reversible temperature-indicating agent is such that the rotation speed and the stirring time when the reversible temperature-indicating agent is mixed with paraffin wax and / or microcrystalline wax. It can be controlled by (emulsification time).

  The particle size of the microcapsule 22 is preferably in the range of 1 μm to 100 μm, and more preferably in the range of 2 μm to 10 μm.

  The reason for this is that when the particle size of the microcapsule 22 is smaller than 1 μm, the visibility of the color change when the cryogen 21 containing the microcapsule is cooled is lowered, and the particle size of the microcapsule 22 is larger than 100 μm. This is because, when the microcapsule 22 is blended with the cooling agent 21, the microcapsule 22 is easily broken. In order to further improve the visibility of the microcapsule 22 and make the microcapsule 22 more difficult to break, the particle size of the microcapsule 22 is more preferably in the range of 2 μm to 10 μm.

  The ratio (mixing amount (volume%)) of the microcapsules 22 in the cooling agent 21 is desirably 1 volume% to 50 volume%. The reason for this is that when the blending amount of the microcapsules 22 is less than 1% by volume, the visibility of the change in color tone when the cooling agent 11 blended with the microcapsules 22 is cooled is lowered, and the blending amount of the microcapsules 22 is 50. This is because, if the volume percentage is exceeded, the cooling performance of the cooling agent 21 is lowered.

  In the second embodiment according to the present invention, a plurality of microcapsules 22 (22a, 22b, 22c) in which a plurality of types of reversible thermostats having different temperatures at which the color changes are accommodated are randomly contained in the cold insulating agent 21. It may be dispersed, or the cryogen 21 may be divided into a plurality of layers, and microcapsules containing the same type of reversible thermostat in each layer may be dispersed. Thereby, by changing the temperature, for example, a device can be obtained in which different colors appear sequentially from right to left or from top to bottom.

  With the reversible thermostat-containing cryogen of the present invention, the temperature of the cryogen can be accurately grasped by the color change of the reversible thermostat dispersed inside. Therefore, even when cooling in a freezer or the like, the guide for the cooling holding time can be known from the change in color, so that the cooling is not excessively performed and the efficiency of the cooling work is improved. It can also be used for temperature management and indicators when delivering frozen foods to retail stores and consumers. Moreover, the reversible thermostat-containing cryogen can be used not only for foods but also for cooling pharmaceuticals and semiconductor products.

It is sectional drawing which shows an example of 1st embodiment of the reversible thermostat containing cryogen which concerns on this invention. It is sectional drawing which shows an example of 2nd embodiment of the reversible thermostat containing cryogen which concerns on this invention. It is a schematic diagram which shows the component structure of the conventional cool storage agent.

Explanation of symbols

  10, 20 Refrigerant containing cold retentive agent, 11, 21 Refrigerant, 12, 22, 22a, 22b, 22c Microcapsules.

Claims (4)

A gel-type cold insulating agent having transparency, and a reversible thermostat-containing cold insulating agent comprising a plurality of microcapsules containing a reversible thermostatic agent,
The microcapsule is dispersed in the cryogen, and the microcapsule has a particle size of 1 μm or more and 100 μm or less. A gel-type cold insulating agent having transparency, and a reversible thermostat-containing cold insulating agent comprising a plurality of microcapsules containing a reversible thermostatic agent,
The microcapsules are dispersed in the cold-retaining agent, and as the reversible temperature-indicating agent, a plurality of types of compositions having different temperatures at which the color changes are used, and each microcapsule is composed of each composition. A cold-retaining agent containing a reversible temperature-indicating agent characterized by containing a temperature-indicating agent.   The particle size of the microcapsule is 1 µm or more and 100 µm or less, and the reversible thermostable cryogen according to claim 2. The refrigerating agent-containing cold retentive agent according to claim 1 or 2, wherein the cold retentive agent contains the microcapsule in an amount of 1 vol% to 50 vol%.

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