A lower critical temperature indicating device

Abstract

The present invention discloses a lower critical temperature indicating device, which comprises a coating layer, at least one capsule located in the coating layer, and a first medium, wherein the at least one capsule is distributed in the first medium, the capsule comprises a capsule wall and a capsule wrapping located inside the capsule wall, the capsule wrapping comprises a second medium, and the second medium forms needle-shaped or sheet-shaped crystals under an environment below a critical temperature to pierce the capsule wall so that the first medium contacts the second medium to cause a color change reaction. The lower critical temperature indicating device of the present invention has a simple structure, high accuracy, and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of temperature monitoring, and in particular to a lower critical temperature indicating device. Background Art

[0002] At present, cold chain products such as dairy products, flowers, blood products, and vaccines need to maintain a certain temperature range during transportation and storage. These products not only require a low temperature environment during the preparation process, but also have to go through a series of cold chain transportation links after leaving the factory before they reach consumers. Each link is a potential risk point. Exceeding the temperature standard in any link in the cold chain may lead to more serious consequences. If problems occur during transportation or storage, it is difficult to identify the responsible party.

[0003] In the prior art, for example, the patent application of the British Timestrip company in China with the patent publication number CN1533518A proposed a color-changing label device. After the capsule containing the solvent is crushed, the solution gradually penetrates into the observation area. It can only measure the cold chain transportation time, but cannot measure whether the cold chain environment exceeds the set dangerous temperature. At the same time, the product has the problems of complex structure and high cost, which limits its promotion and application. In addition, the function of such temperature indicator labels in the prior art is mostly to monitor whether the temperature exceeds the set safety temperature, but cannot monitor the lower limit of the temperature. For example, the optimal storage temperature of the vaccine is 5°C. Too high or too low temperature will cause irreversible inactivation of the vaccine. Therefore, it is necessary to develop an irreversible color-changing device that indicates the lower critical temperature. In addition, the existing temperature indicator labels can only be manually identified based on the emitted visible light, and cannot be machine-recognized, which is not conducive to large-scale identification and application. Summary of the invention

[0004] The purpose of the present invention is to address the above technical problems existing in the prior art and to provide a lower critical temperature indicating device with simple structure, high accuracy and low cost.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A lower critical temperature indicating device comprises a coating layer, at least one capsule located in the coating layer, and a first medium, wherein the at least one capsule is distributed in the first medium, the capsule comprises a capsule wall and a capsule wrapping located inside the capsule wall, the capsule wrapping comprises a second medium, and the second medium forms needle-shaped or flaky crystals in an environment below the lower critical temperature, piercing the capsule wall so that the first medium contacts the second medium and a color change reaction occurs.

[0007] Preferably, the second medium is selected from one or more of esters, aromatics, alcohols, organic acids, organic amines, and ketones.

[0008] Preferably, the second medium is selected from ethyl 2-aminobenzoate, dimethyl sebacate, diethyl sebacate in esters, or from 1-acetylnaphthalene, diphenylmethane, phenylcyclohexane, anisene in aromatics, or from succinic acid, monohydrated citric acid in organic acids, or from indole, isoquinoline in organic amines, or from benzyl alcohol, p-phenylenediol in alcohols, or from diacetyl in ketones.

[0009] Preferably, the capsule packaging further comprises a color-changing dye, and the color-changing dye undergoes a color-changing reaction when in contact with the first medium.

[0010] Preferably, the color-changing dye includes one or more of bromothymol blue, bromocresol green, methyl yellow, methyl red, methyl orange, bromocresol green, phenolphthalein, chlorophyll-16, erythrocyte-5, melanin-1, crystal violet lactone, benzoyl colorless methylene blue, solvent red 5, solvent red 18, solvent blue 63, solvent blue 104, solvent green 3, solvent green 28, solvent violet 13, solvent violet 14, solvent violet 36, solvent violet 59, solvent black 4, and solvent black 5.

[0011] Preferably, the color-changing dye is an infrared color-changing dye or an ultraviolet color-changing dye.

[0012] Preferably, the infrared light color-changing dye is selected from one or more of cyanine infrared absorbing dyes, crotonyl cyanine infrared absorbing dyes, metal complex dyes, or is selected from near-infrared fluorescent materials that can absorb infrared light and convert it into visible light.

[0013] Preferably, the ultraviolet color-changing dye is selected from one or more of UV-9 and UV-531 in the benzophenone class, and UV-326 and UV-328 in the benzotriazole class.

[0014] Preferably, the first medium is selected from one or more of aromatics, organic acids, and esters.

[0015] Preferably, the first medium is selected from one or more of cyclohexyl acetate, glycerol, benzoic acid, citric acid monohydrate, ethyl acetate, dimethyl carbonate, tartaric acid, and butyrolactone.

[0016] Preferably, the crystallization temperature of the second medium is in the range of -25°C to 50°C.

[0017] The lower critical temperature indicating device of the present invention has simple structure, high accuracy and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention may be better understood by reference to the accompanying drawings which illustrate embodiments of the invention, in which:

[0019] Figure 1 is a schematic cross-sectional structural diagram of a lower critical temperature indicating device according to a specific embodiment of the present invention;

[0020] Figure 2 is an enlarged structural schematic diagram of a capsule in a lower critical temperature indicating device according to a specific embodiment of the present invention;

[0021] Figure 3 Schematic diagrams of several planar structures of the lower critical temperature indicating device according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0022] In the following description, a large number of specific details are set forth for the purpose of explanation so as to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without these specific details. The illustrative exemplary embodiments listed in the present invention are only for illustration and do not limit the present invention. Therefore, the protection scope of the present invention is not limited by the specific embodiments, but only by the scope of the attached claims.

[0023] Figure 1 is a schematic cross-sectional structural diagram of a lower critical temperature indicating device according to a specific embodiment of the present invention, Figure 2 is an enlarged structural schematic diagram of a capsule in a lower critical temperature indicating device according to a specific embodiment of the present invention, combined with Figure 1 and Figure 2 As shown, a lower critical temperature indicating device according to a specific embodiment of the present invention comprises a coating layer 10 and at least one capsule 20 and a first medium 30 located in the coating layer 10, wherein the at least one capsule 20 is distributed in the first medium 30, the capsule 20 comprises a capsule wall 21 and a capsule wrapping 22 located inside the capsule wall 21, the capsule wrapping 22 comprises a second medium 221, and the second medium 221 forms needle-shaped or flaky crystals in an environment below the lower critical temperature to pierce the capsule wall 21, so that the first medium 30 contacts the second medium 221 to cause a color change reaction.

[0024] In a specific embodiment of the present invention, the second medium 221 can be selected from one or more of esters, aromatics, alcohols, organic acids, organic amines, and ketones. For example, the second medium 221 is selected from 2-aminobenzoic acid ethyl ester, dimethyl sebacate, and diethyl sebacate in esters, or 1-acetylnaphthalene, diphenylmethane, phenylcyclohexane, and anisene in aromatics, or succinic acid and citric acid monohydrate in organic acids, or indole and isoquinoline in organic amines, or benzyl alcohol and terephthalene alcohol in alcohols, or diacetyl in ketones. The second medium 221 can also be selected from a mixture of two or more of the above materials, as long as it can crystallize itself at a temperature below a certain temperature and can pierce the capsule wall 221 that wraps it.

[0025] In a specific embodiment of the present invention, the capsule wrapping 22 may further include a color-changing dye 222, and the color-changing dye 222 reacts with the first medium 30 to change color. Preferably, the color-changing dye 222 includes one or more of bromothymol blue, bromocresol green, methyl yellow, methyl red, methyl orange, bromocresol green, phenolphthalein, green pigment-16, red pigment-5, melanin-1, crystal violet lactone, benzoyl colorless methylene blue, solvent red 5, solvent red 18, solvent blue 63, solvent blue 104, solvent green 3, solvent green 28, solvent violet 13, solvent violet 14, solvent violet 36, solvent violet 59, solvent black 4, and solvent black 5.

[0026] In a specific embodiment of the present invention, the color-changing dye 222 can adopt the above visible light color-changing dye, but is not limited thereto. The color-changing dye 222 can also be one of a visible light color-changing dye, an infrared light color-changing dye and an ultraviolet light color-changing dye, or can also include two or more visible light or infrared light or ultraviolet light color-changing dyes at the same time. For example, the infrared light color-changing dye is selected from one or more of cyanine infrared absorption dyes, cyanine infrared absorption dyes, and metal complex dyes, or is selected from near-infrared fluorescent materials that can absorb infrared light and convert infrared light into visible light. The ultraviolet color-changing dye is selected from one or more of UV-9, UV-531 in dibenzophenones, and UV-326 and UV-328 in benzotriazoles. The use of infrared light color-changing dyes or ultraviolet light color-changing dyes is helpful to use a machine to identify the absorbed light or the emitted light, thereby realizing the machine identification of the lower critical temperature indicating device.

[0027] In a specific embodiment of the present invention, the first medium 30 is selected from one or more of aromatics, organic acids, organic amines, and esters. For example, the first medium 30 is selected from one or more of cyclohexyl acetate, glycerol, benzoic acid, citric acid monohydrate, ethyl acetate, dimethyl carbonate, tartaric acid, and butyrolactone. However, the present invention is not limited thereto, as long as the first medium 30 can contact at least one of the second medium 221 or the color-changing dye 222 in the capsule wrapping 22 that has been punctured when the lower critical temperature is reached to cause a color change reaction.

[0028] In a specific embodiment of the present invention, preferably, the crystallization temperature of the second medium 221 is in the range of -25°C to 50°C. Different materials or material ratios can be used to adjust the crystallization temperature according to different application scenarios, thereby forming a device with different lower critical temperature indications.

[0029] First embodiment:

[0030] In this embodiment, the method for preparing capsule 20 by complex coacervation is as follows: gelatin and gum arabic are mixed and dissolved in a ratio of 5 parts each, and 10 parts of the second medium 221 are added. In this embodiment, the second medium 221 is a mixture of succinic acid, diethyl sebacate and UV-531, and the mass ratio of succinic acid, diethyl sebacate and UV-531 is 1:100:0.6. The ratio is adjusted to control the crystallization temperature to -10°C. After mixing and emulsifying by a high-speed disperser, it is poured into a reactor, diluted with distilled water to a wall material concentration of 1%, stirred at 40°C, and the pH value is adjusted to 4.0 with acetic acid aqueous solution, kept constant for 15 minutes, then reduced to 10°C, and the pH value is adjusted to 6.0, and then glutamine aminotransferase is added to solidify the wall material to obtain a capsule dispersion solution, and finally post-processed to obtain a capsule product. Then, the capsule 20 is dispersed in the first medium 30, and the amount of the capsule is 50% of the mass of the first medium.

[0031] In this embodiment, the first medium 30 is a mixture of cyclohexyl acetate and bromothymol blue, and the mass ratio of cyclohexyl acetate to bromothymol blue is 100:0.6. In the lower critical temperature indicating device of this embodiment, when the temperature is lower than -10°C, the second medium 221 crystallizes to form a needle or sheet-like object to pierce the capsule wall 21, so that succinic acid contacts bromothymol blue, causing the structure of bromothymol blue itself to change, and the macroscopic manifestation is a change from blue to yellow. At the same time, UV-531 is released into the first medium, so that the first medium has a strong absorption of light with a wavelength range of 280nm-380nm, and can be recognized by the machine.

[0032] Second embodiment:

[0033] In this embodiment, the method for preparing capsule 20 by in-situ polymerization is as follows: add 20% NaOH aqueous solution to a mixed solution of 100 parts of 10% ethylene-maleic anhydride copolymer aqueous solution, 10 parts of urea, 1 part of resorcinol and 200 parts of water, adjust the pH value to 3.5, then add 200 parts of the second medium 221 (a mixed solution of color-changing dye methyl yellow and diacetyl, the mass ratio of methyl yellow and diacetyl is 0.3:100, and the crystallization temperature of the mixture is 15°C) to the above solution and stir and emulsify. Then add 25 parts of formalin, stir and heat to 55°C, keep warm for 2 hours under continuous stirring, and then cool to room temperature. Finally, wash, filter and dry to obtain a capsule product. Then disperse the capsule product in the first medium 30, and the capsule mass fraction is 30% of the first medium.

[0034] The first medium of this embodiment is a mixture of glycerol and a small amount of benzoic acid, and the mass ratio of glycerol to benzoic acid is 100:0.3. When the lower critical temperature indicating device of this embodiment is in use, when the temperature is lower than 15°C, the second medium 221 crystallizes into a needle or sheet-like object to pierce the capsule wall 21, so that the methyl yellow contacts the benzoic acid in the first medium, thereby changing the structure of the indicator methyl yellow itself, and the macroscopic performance is changed from yellow to red.

[0035] Third embodiment:

[0036] In this embodiment, the method for preparing capsule 20 by in-situ polymerization is as follows: 150 parts of 5% Tween 80 aqueous solution, 15 parts of urea, 1.5 parts of resorcinol and 300 parts of water are added to the reactor by mass, and the pH value is adjusted to 3.5 using 20% ​​NaOH. Then, the second medium 221 (a mixed solution of red pigment-1, near-infrared dye IR5753 and phenylcyclohexane, the mass ratio of red pigment-1, near-infrared dye IR5753 and phenylcyclohexane is 0.3:0.3:100) is added to the above solution and stirred and emulsified, and the crystallization temperature of the second medium 221 is 4°C. Then, 37.5 parts of formalin are added, stirred and heated to 55°C, kept warm for 2 hours under continuous stirring, and then cooled to room temperature, and finally washed, filtered and dried to obtain a capsule product, and then the capsule product is dispersed in the first medium 30, and the mass ratio of capsule to the first medium is 2:1.

[0037] The first medium 30 of this embodiment is a mixture of glycerol and citric acid monohydrate, and the mass ratio of glycerol to citric acid monohydrate is 100:15. In the use of the lower critical temperature indicating device of this embodiment, when the temperature is lower than 4°C, the second medium 221 crystallizes to form a needle or sheet-like object to pierce the capsule wall 21, so that the red pigment-1 contacts with citric acid monohydrate, and a chemical complex reaction occurs, which will turn the colorless red pigment-1 into red, and the red color is the coordination complex of red pigment-1 and citric acid. At the same time, the near-infrared dye IR5753 will be released into the first medium, so that the first medium has a strong absorption of light with a wavelength range of 800nm-1200nm and can be recognized by the machine.

[0038] Fourth embodiment:

[0039] In this embodiment, the method for preparing capsule 20 by interfacial polymerization is as follows: the ratio of isoquinoline and indole in the second medium is adjusted so that its crystallization temperature is 15°C, then 18 parts of the above mixed solution are taken, 2 parts of isophorone diisocyanate and 1 part of propylene oxide are added, and then the solution is added to 100 parts of an aqueous solution containing 15 parts of PVA in the form of droplets of 50-100 μm. The obtained dispersion is heated to 30°C under stirring, and 10 parts of an aqueous solution containing 0.5 parts of ethylenediamine are added dropwise to the above dispersion. The obtained dispersion is stirred for another 3 hours to obtain a capsule product, and then the capsule is dispersed in the first medium 30, and the amount of the capsule is 10% of the first medium.

[0040] The first medium 30 of this embodiment is a mixture of ethyl acetate, bromocresol green and a trace amount of citric acid monohydrate, and the mass ratio of ethyl acetate, bromocresol green and citric acid monohydrate is 100:1:5. When the lower critical temperature indicating device of this embodiment is in use, when the temperature is lower than 15°C, the second medium 221 crystallizes to form a needle or sheet-like object to pierce the capsule wall 21, so that the isoquinoline and indole in the second medium are in contact with the bromocresol green and a trace amount of citric acid monohydrate in the first medium, so that the first medium changes from acidic to alkaline, and the bromocresol green changes from yellow in an acidic environment to blue-green.

[0041] Fifth embodiment:

[0042] In this embodiment, the method for preparing capsule 20 by in-situ polymerization is as follows: 150 parts of 5% Tween 80 aqueous solution, 15 parts of urea, 1.5 parts of resorcinol and 300 parts of water are added to the reactor by mass, and the pH value is adjusted to 3.5 using 20% ​​NaOH, and then 250 parts of the second medium (a mixed solution of color-changing dye crystal violet lactone and diacetyl, the mass ratio of crystal violet lactone to diacetyl is 0.6:100, and its crystallization temperature is -8°C) is added to the above solution and stirred and emulsified, and then 37.5 parts of formalin are added, stirred and heated to 55°C, and kept warm for 2 hours under continuous stirring, and then cooled to room temperature. Finally, the capsule product is washed, filtered and dried to obtain the capsule product, and then the capsule is dispersed in the first medium 30, and the capsule is 40% of the first medium.

[0043] The first medium 30 of this embodiment is a mixture of dimethyl carbonate and trace tartaric acid, and the mass ratio of dimethyl carbonate to trace tartaric acid is 100:5. When the lower critical temperature indicating device of this embodiment is in use, when the temperature is lower than -8°C, the second medium 221 crystallizes to form a needle or sheet to pierce the capsule wall 21, so that the crystal violet lactone contacts with tartaric acid, and a chemical complex reaction occurs, which will turn the colorless crystal violet lactone into a bright blue-purple color, which is a coordination complex of red crystal violet lactone and tartaric acid.

[0044] Sixth embodiment:

[0045] In this embodiment, the method for preparing capsule 20 by in-situ polymerization is as follows: 150 parts of 5% Tween 80 aqueous solution, 15 parts of urea, 1.5 parts of resorcinol and 300 parts of water are added to the reactor by mass, and the pH value is adjusted to 3.5 using 20% ​​NaOH, and then 250 parts of the second medium 221 (a mixed solution of solvent violet 14, p-phenylenediol and isoquinoline, the mass ratio of solvent violet 14, p-phenylenediol and isoquinoline is 0.6:100:5, and the crystallization temperature is 25°C) is added to the above solution and stirred and emulsified. Then 37.5 parts of formalin are added, stirred and heated to 55°C, kept warm for 2 hours under continuous stirring, then cooled to room temperature, and finally washed, filtered and dried to obtain a capsule product, and then the capsule product is dispersed in the first medium 30, and the mass ratio of capsule to the first medium is 1:1.

[0046] The first medium 30 of this embodiment is butyrolactone. When the product is in use, the lower critical temperature indicating device of this embodiment is in use, when the temperature is lower than 25°C, the second medium 221 crystallizes to form a needle or sheet-like object to pierce the capsule wall 21, so that the solvent violet 14 is released from the capsule into the first medium, causing the colorless first medium to undergo a physical dye process, and the colorless first medium will turn purple.

[0047] The lower critical temperature indicating device of the present invention can be configured in various structural shapes according to actual needs, such as Figure 3 As shown, Figure 3 The following are several schematic diagrams of the planar structures of the lower critical temperature indicating device of the specific embodiment of the present invention. For example, it can be set to a label structure of a circle, oval, triangle, square, pentagon, hexagon, rectangle, other polygons or other arbitrary shapes. The area occupied by the first medium and the capsule inside can also be set to a circle, oval, triangle, square, pentagon, hexagon, rectangle, other polygons or other arbitrary shapes. The graphic structure will not be repeated. In addition, the lower critical temperature indicating device can also be provided with a protective layer or an observation window layer on the outer layer, and an adhesive layer and a release film layer on the bottom layer as needed. Other additional specific applicable structures are not listed one by one.

[0048] The lower critical temperature indicating device of the present invention, when the lower limit of temperature is lower than the set dangerous temperature, the temperature indicating label of the present invention changes from colorless to colored or from one color to another color, and optionally can also realize infrared light or ultraviolet light machine recognition function at the same time, which can be applied to the detection of specific occasions or specific products, and plays the dual functions of anti-counterfeiting and temperature indication, broadening the application scenarios and scope of the present invention, and the color change process is irreversible, thereby avoiding the risk of human tampering with the results, and has the advantages of simple structure, high accuracy and low cost.

[0049] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A lower critical temperature indicating device, characterized in that: The lower critical temperature indicating device includes a coating layer, at least one capsule located in the coating layer, and a first medium, wherein the at least one capsule is distributed in the first medium, the capsule includes a capsule wall and a capsule wrapping located inside the capsule wall, and the capsule wrapping includes a second medium, wherein the second medium forms needle-shaped or flaky crystals in an environment below the lower critical temperature and pierces the capsule wall, causing the first medium to come into contact with the second medium to undergo a color change reaction.

2. The lower critical temperature indicating device according to claim 1, characterized in that: The second medium is selected from one or more of esters, aromatics, alcohols, organic acids, organic amines, and ketones.

3. The lower critical temperature indicating device according to claim 2, characterized in that: The second medium is selected from ethyl 2-aminobenzoate, dimethyl sebacate, and diethyl sebacate in esters, or from 1-acetylnaphthalene, diphenylmethane, phenylcyclohexane, and anisene in aromatics, or from succinic acid and citric acid monohydrate in organic acids, or from indole and isoquinoline in organic amines, or from benzyl alcohol and terephthalylinol in alcohols, or from diacetyl in ketones.

4. The lower critical temperature indicating device according to claim 1, characterized in that: The capsule wrapper also includes a color-changing dye, and the color-changing dye undergoes a color-changing reaction when in contact with the first medium.

5. The lower critical temperature indicating device according to claim 4, characterized in that: The color-changing dye includes bromothymol blue, bromocresol green, methyl yellow, methyl red, methyl orange, bromocresol green, phenolphthalein, green pigment-16, red pigment-5, melanin-1, crystal violet lactone, benzoyl colorless methylene blue, solvent red 5, solvent red 18, solvent blue 63, solvent blue 104, solvent green 3, solvent green 28, solvent violet 13, solvent violet 14, solvent violet 36, solvent violet 59, solvent black 4, and solvent black 5. One or more of the following.

6. The lower critical temperature indicating device according to claim 4, characterized in that: The color-changing dye is an infrared color-changing dye or an ultraviolet color-changing dye.

7. The lower critical temperature indicating device according to claim 6, characterized in that: The infrared light color-changing dye is selected from one or more of cyanine infrared absorbing dyes, crotonyl cyanine infrared absorbing dyes, and metal complex dyes, or is selected from near-infrared fluorescent materials that can absorb infrared light and convert it into visible light.

8. The lower critical temperature indicating device according to claim 6, characterized in that: The ultraviolet color-changing dye is selected from one or more of UV-9 and UV-531 in the benzophenone class, and UV-326 and UV-328 in the benzotriazole class.

9. The lower critical temperature indicating device according to claim 1, characterized in that: The first medium is selected from one or more of aromatics, organic acids, and esters.

10. The lower critical temperature indicating device according to claim 9, characterized in that: The first medium is selected from one or more of cyclohexyl acetate, glycerol, benzoic acid, citric acid monohydrate, ethyl acetate, dimethyl carbonate, tartaric acid, and butyrolactone.

11. The lower critical temperature indicating device according to claim 1, characterized in that: The crystallization temperature of the second medium is in the range of -25°C to 50°C.

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