A smart label for frozen storage and transportation and its preparation method and application

Abstract

The present invention discloses a smart label for frozen storage and transportation, and a preparation method and application thereof, which belongs to the field of material synthesis and indication products. The present invention selects two types of organic solvents, namely, suitable alkanes and alcohols, to prepare a compound solvent; then, a color former and a developer are added into the compound solvent to react to obtain a sub-zero color-changing temperature-sensitive material that can be used in a low-temperature environment; finally, the sub-zero color-changing temperature-sensitive material is used as a printing solution, coated on a substrate to form a two-dimensional code, and a smart label is obtained. The preparation method of the sub-zero color-changing temperature-sensitive material of the present invention is simple and the preparation cost is low. The phase change can be used to realize color change within a specific sub-zero temperature range, which can meet the requirements of freezing temperature monitoring. The smart label of the present invention can effectively sense the temperature changes in the transportation and storage environment through the information feedback function of the two-dimensional code and provide a visual signal response to realize real-time temperature monitoring.

Description

Technical Field

[0001] The invention relates to an intelligent label for frozen storage and transportation and a preparation method and application thereof, belonging to the field of material synthesis and indication products. Background Art

[0002] With the deepening of globalization and the continuous extension of supply chains, the market demand for efficient refrigerated logistics is growing rapidly. In order to ensure the quality and safety of frozen products during storage and transportation, it is essential to use efficient and reliable technology to monitor temperature changes.

[0003] Today, cold chain monitoring relies primarily on two types of technologies: electronic and non-electronic.

[0004] Among electronic technologies, radio frequency identification (RFID) tags are the mainstream technology used for frozen storage and transportation monitoring because they can record and track temperature changes in real time. However, this type of tag is large in size, expensive, and sometimes requires an external power source, which has certain limitations in practical applications. In addition, although near-field communication (NFC) electronic tags have low environmental requirements, they are susceptible to electromagnetic interference and have limited data storage capacity, making it difficult to meet monitoring needs in long-distance transportation. In addition, during the transportation process of the supply chain, counterfeiters will hide the thermometer in an ice bag, which poses a certain risk to the safety of cold chain transportation.

[0005] Non-electronic temperature labels are mainly based on the color change caused by heating of certain chemical substances to indicate temperature. Common inorganic materials include iodides, complexes, organometallic compounds, etc., and the color change temperature is mostly above 100°C, which does not include the main temperature indicators involved in frozen storage and transportation. Common organic materials, such as spiropyran, fluorescent derivatives, polythiophene, liquid crystal materials, etc., are usually only used to monitor the temperature range above zero, and it is difficult to cope with the low or ultra-low temperature monitoring needs that often occur in the storage and transportation of frozen goods.

[0006] CN107016926A discloses a non-electronic label for cold chain transportation, wherein the thermochromic material is a color-changing ink, and the thermochromic process is irreversible, with a temperature range of -5°C to 10°C. CN 103333582 B discloses an irreversible thermochromic material prepared using crystal violet lactone and bisphenol A, with a temperature range of 45°C to 52°C. The above technology has the problem of high detection temperature, and it is difficult to detect storage conditions under a frozen state of -20°C.

[0007] In view of these limitations of existing technologies, there is an urgent need to innovate and develop new sub-zero temperature-sensitive materials, combine them with smart label technology, and apply them to the surface of frozen product outer packaging materials. This can hopefully achieve full intelligent supervision of product quality and safety during storage and transportation throughout the entire supply chain, provide more reliable, efficient and intelligent solutions for global frozen storage and transportation, and is of great significance to improving global public health levels and food safety standards. Summary of the invention

[0008] [Technical issues]

[0009] The existing monitoring technology for frozen storage and transportation is expensive, its use is subject to environmental restrictions, and it cannot meet the main temperature indicators required for monitoring during frozen storage and transportation, such as -18°C.

[0010] [Technical solution]

[0011] In order to solve at least one of the above problems, the present invention selects two types of organic solvents, namely alkanes and alcohols, and compound them in a certain proportion to obtain a compound solvent; then, a color former and a developer are added to the compound solvent to react to obtain a sub-zero color-changing temperature-sensitive material that can be used in a low-temperature environment; finally, the sub-zero color-changing temperature-sensitive material is used as a printing solution, coated on a substrate, and a two-dimensional code is formed to obtain a smart label. The preparation method of the sub-zero color-changing temperature-sensitive material of the present invention is simple and the preparation cost is low. The phase change can be used to achieve color change within a specific sub-zero temperature range, which can meet the requirements of freezing temperature monitoring. The smart label of the present invention can effectively sense the temperature changes in the transportation and storage environment and provide a visual signal response through the information feedback function of the two-dimensional code, thereby realizing real-time temperature monitoring.

[0012] The first object of the present invention is to provide a method for preparing a sub-zero color-changing temperature-sensitive material, comprising the following steps:

[0013] (1) uniformly mixing an alkane organic solvent and an alcohol organic solvent to form a mixed solvent;

[0014] Wherein, the alkane organic solvent is one or more of n-decane, n-undecane, n-dodecane and n-hexadecane;

[0015] The alcohol organic solvent is one or more of n-dodecyl alcohol, n-tetradecyl alcohol, n-hexadecanol, and n-octadecyl alcohol;

[0016] (2) mixing the mixed solvent, the color former, and the color developer, and reacting them to obtain a sub-zero color-changing temperature-sensitive material;

[0017] Wherein, the coloring agent is one of crystal violet lactone, cresol red, and malachite green;

[0018] The color developer is one of bisphenol A, lauryl acetate, and 4-hydroxycoumarin.

[0019] In one embodiment of the present invention, the volume percentage of the alkane organic solvent in the mixed solvent of step (1) is 20-98%.

[0020] In one embodiment of the present invention, the ratio of the mixed solvent, the color former and the developer in step (2) is 9-12 mL: 80-120 mg: 80-120 mg.

[0021] In one embodiment of the present invention, the reaction in step (2) is carried out by stirring at 34-36° C. and 400-800 rpm for 12-48 hours.

[0022] In one embodiment of the present invention, the reaction in step (2) can be carried out in a magnetically stirred water bath.

[0023] The second object of the present invention is the sub-zero color-changing temperature-sensitive material prepared by the method described in the present invention.

[0024] In one embodiment of the present invention, the color change temperature of the sub-zero color-changing temperature-sensitive material is -16 to -20°C.

[0025] A third object of the present invention is to provide a method for preparing a smart label for frozen storage and transportation, comprising the following steps:

[0026] The sub-zero color-changing temperature-sensitive material is used as a printing solution and coated on a substrate to form a two-dimensional code, thereby obtaining a smart label for frozen storage and transportation.

[0027] In one embodiment of the present invention, the substrate is one of paper, plastic, glass and the like.

[0028] In one embodiment of the present invention, the substrate is wood pulp paper.

[0029] In one embodiment of the present invention, the coating is performed by dipping an acrylic two-dimensional code stamp into a sub-zero color-changing temperature-sensitive material for printing.

[0030] The fourth objective of the present invention is the smart label for frozen storage and transportation prepared by the method described in the present invention.

[0031] In one embodiment of the present invention, the QR code in the smart label used for frozen storage and transportation can be scanned by a smart device to obtain information; once the QR code cannot be recognized, it can be confirmed that the temperature is out of control.

[0032] In one embodiment of the present invention, during transportation and storage, the color of the smart label will change with the temperature. If the temperature is out of control, the QR code pattern will be destroyed. Even if the temperature is subsequently reset to the specified temperature, the QR code will still not be recognizable, thereby being able to judge the temperature conditions during storage.

[0033] In one embodiment of the present invention, the basic configuration of the smart device should reach 3 million pixels.

[0034] A fifth object of the present invention is to provide a packaging material for frozen products, which uses the smart label or sub-zero color-changing temperature-sensitive material of the present invention.

[0035] The sixth objective of the present invention is to use the smart label or sub-zero color-changing temperature-sensitive material of the present invention in the field of frozen storage and transportation.

[0036] In one embodiment of the present invention, the smart label or sub-zero color-changing temperature-sensitive material can be used in the field of frozen transportation of food.

[0037] The seventh object of the present invention is to provide a method for detecting product quality during frozen transportation and storage, which uses the smart label or sub-zero color-changing temperature-sensitive material described in the present invention.

[0038] In one embodiment of the present invention, during the storage and transportation of frozen products, if the QR code pattern cannot be recognized by a smart phone, it is determined that the temperature is out of control.

[0039] [Beneficial Effects]

[0040] (1) The present invention utilizes organic solvents with different melting points for compounding to meet the requirements of different temperature indicators during frozen storage and transportation, and the monitoring temperature can reach -20±1°C.

[0041] (2) The present invention can realize visual signal output with the help of a color developer (bisphenol A) and a color former (crystal violet lactone). The color change of the prepared temperature-sensitive material is that the material appears bluish purple at -20±1°C and light blue at 20±1°C, and the color change is obvious.

[0042] (3) The present invention combines temperature-sensitive materials with QR code technology to design an intelligent label for frozen storage and transportation. Through the information feedback function of the QR code and the color change produced by the material, the temperature changes in the transportation and storage environment are effectively sensed. At the same time, the label can be directly identified by smart devices.

[0043] (4) The smart label described in the present invention is simple to prepare and inexpensive, and can be directly prepared on the surface of the outer packaging material of frozen products, thereby realizing the whole process of intelligent supervision of product quality and safety during the storage and transportation of the entire supply chain.

[0044] (5) The smart label of the present invention cannot be identified after the temperature is out of control and the process is irreversible. The smart label is printed on the outer surface of the cold chain product, which effectively prevents the occurrence of counterfeiting such as the thermometer hidden in the ice bag during cold chain transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The differential scanning calorimetry (DSC) curves of the temperature sensitive materials (TCMs) and the mixed solvent in Example 1 are shown.

[0046] Figure 2 The color changes of the temperature-sensitive material and the wood pulp paper coated thereon in Example 1 at -20°C and 20°C.

[0047] Figure 3 These are images taken at different temperature points of the wood pulp paper coated with the temperature-sensitive material in Example 1.

[0048] Figure 4 The chromaticity value change of the temperature-sensitive material in Example 1 during the temperature change process.

[0049] Figure 5 The DSC curves of the temperature-sensitive material with different cycle numbers and the phase change characteristics analysis with the cycle numbers.

[0050] Figure 6 The n-undecane-n-dodecanol solvent system (C 11- 12OH solvent system), where the left figure is the melting curve and the right figure is the crystallization curve.

[0051] Figure 7 This is a smart QR code label constructed using the temperature-sensitive material in Example 5. DETAILED DESCRIPTION

[0052] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0053] Test method:

[0054] (1)DSC curve test:

[0055] DSC tests were carried out on mixed solvents with different ratios of n-dodecanol and n-undecane and the temperature-sensitive materials prepared therefrom. The test conditions were as follows: heating range: -50℃ to 40℃, mixed solvent test amount: 10mg, heating rate and cooling rate: 10℃ / min, to explore the thermodynamic properties of the prepared materials.

[0056] (2) Infrared test:

[0057] Infrared was used to characterize crystal violet lactone, bisphenol A and the prepared temperature-sensitive material, respectively, to explore the changes in functional groups during the material preparation process.

[0058] (3) Chromaticity value test:

[0059] Use PS software to absorb the main colors photographed at different temperature points, obtain RGB values, and plot them in the CIE1931 colorimetric diagram.

[0060] (4) Phase change characteristics test:

[0061] The temperature-sensitive material was subjected to DSC tests with different cycle numbers, ranging from 1 to 20 times. The DSC curves of the first, 5th, 10th and 20th cycles were selected for phase change characteristic analysis.

[0062] Materials used in the embodiments and comparative examples:

[0063] Wood pulp paper: Specifications: Chenguang A4 paper, paper weight: 80g / m 2 , Paper whiteness: pure white, the size will be cut according to the experimental requirements, the original A4 size is 210mm*297mm.

[0064] Example 1

[0065] A method for preparing a sub-zero color-changing temperature-sensitive material comprises the following steps:

[0066] (1) n-dodecanol and n-undecane are mixed uniformly to obtain a mixed solvent (C 11- 12OH solvent system); wherein the volume fraction of n-undecane is 96%;

[0067] (2) 10 mL of the mixed solvent, 100 mg of crystal violet lactone and 100 mg of bisphenol A were mixed and reacted in a water bath at 35±1°C at 400 rpm for 12 h to obtain a subzero color-changing temperature-sensitive material (hereinafter referred to as a temperature-sensitive material, TCMs).

[0068] The obtained mixed solvent (C 11- 12OH solvent system) and sub-zero color-changing temperature-sensitive materials were tested for performance, and the test results are as follows:

[0069] Figure 1 is the DSC curve of the temperature-sensitive material in Example 1. Figure 1 It can be seen that the melting and crystallization process of the materials is at -40 to -20°C, which can meet the needs of subsequent experiments.

[0070] Place the temperature-sensitive material in a test chamber at -20±1℃ and 20±1℃, and record the color change of the prepared material; the results are as follows Figure 2 ,from Figure 2 It can be seen that when the temperature-sensitive material is placed in a -20±1℃ environment, its color appears bluish purple. When placed in a 20±1℃ environment, its color changes to light blue. When the wood pulp paper coated with the temperature-sensitive material is placed in a -20±1℃ environment, its color appears bluish purple. When placed in a 20±1℃ environment, its color changes to colorless.

[0071] Dip the temperature-sensitive material and apply it on the wood pulp paper, place the paper in an ambient temperature test chamber of -40±1℃ to 10±1℃, and record the color change corresponding to the temperature; the results are as follows Figure 3 ,from Figure 3 It can be seen that the color of wood pulp paper coated with temperature-sensitive material does not change between -40℃ and -18℃. At -16℃, the color changes significantly, with part of the material turning colorless. At -10℃, the color changes significantly, with a large amount of material turning colorless. At higher temperatures (-5~10℃), the temperature-sensitive material attached to the surface of the wood pulp paper almost completely turns colorless.

[0072] Figure 4 is the chromaticity value change of the temperature-sensitive material in Example 1 during the temperature change process. Figure 4 It can be seen that the color changes of the material are: dark blue-purple (-40℃) - blue-purple (-20℃) - white (10℃).

[0073] Figure 5 The DSC curves of temperature-sensitive materials with different cycle numbers and the analysis of their phase change characteristics with cycle numbers are shown in Figure 2. Figure 5 It can be seen that: as the number of cycles increases, the phase change characteristics of the material are not affected, and it still meets the requirements of melting and crystallization between -40 and -20°C. This shows that the prepared temperature-sensitive material has good stability.

[0074] Example 2

[0075] The volume fraction of n-undecane in step (1) of the embodiment was adjusted to 80%, 90%, 92%, 94% and 98%, and the other contents were kept consistent with those in embodiment 1 to obtain a temperature sensitive material.

[0076] The obtained temperature-sensitive material was subjected to performance testing, and the test results are as follows:

[0077] Figure 6 is the melting crystallization curve of the n-undecane-n-dodecanol solvent system in Example 1 and Example 2. Figure 6 It can be seen that when the volume fraction of n-undecane is 96%, the melting crystallization process of the n-undecane-n-dodecanol solvent system is lower than -20°C, and the melting process of the temperature-sensitive material composited with this solvent system is between -15°C and -30°C ( Figure 1 ), which can better meet the demand for color change at -18±2℃ in the subsequent color change point characterization, and has higher sensitivity and accuracy.

[0078] Example 3

[0079] The contents of the color developer bisphenol A and the color former crystal violet lactone in step (2) of Example 1 were adjusted to 80 mg, 100 mg, and 120 mg, respectively, and the rest were kept consistent with Example 1 to obtain a temperature-sensitive material.

[0080] The obtained temperature-sensitive material was subjected to performance testing, and the test results are as follows:

[0081] When the content of the developer is 100 mg and the content of the color former is 100 mg, which are dissolved in 10 mL of the compounded solvent, the color of the prepared temperature-sensitive material on the wood pulp paper is more obvious, and no excessive precipitation occurs during the preparation process, which is more suitable for the subsequent printing of QR codes.

[0082] When the content of the developer is 80 mg and the content of the color former is 80 mg, the color of the prepared temperature-sensitive material attached to the wood pulp paper is not obvious enough;

[0083] When the content of the developer is 120 mg and the content of the color former is 120 mg, it is difficult to disperse them evenly during the preparation process and a certain amount of precipitation will occur.

[0084] Example 4

[0085] The reaction temperature in step (2) of Example 1 was adjusted to 25 and 55° C., while the other conditions were kept consistent with Example 1 to obtain a temperature-sensitive material.

[0086] The obtained temperature-sensitive material was subjected to performance testing, and the test results are as follows:

[0087] When the reaction temperature is 35°C, the color developer and the color forming agent can be mixed evenly. When the temperature is too low, the color developer and the color forming agent cannot be completely dissolved. When the temperature is too high, the prepared material appears light blue. In subsequent tests, the color changing performance of the material prepared under higher temperature conditions did not reach the expected excellent level.

[0088] Example 5

[0089] A method for preparing a smart label for frozen storage and transportation comprises the following steps:

[0090] Use the program to design a QR code pattern that reflects the monitoring information, and customize the corresponding acrylic QR code stamp;

[0091] The sub-zero color-changing temperature-sensitive material prepared in Example 1 was used as a printing solution, and a stamp was used to dip the prepared temperature-sensitive material, and printed on wood pulp paper to form a two-dimensional code, thereby obtaining a smart label for frozen storage and transportation.

[0092] The prepared smart label was stored in a -20±1°C refrigerator, and the QR code appeared blue-purple and was scanned with a smartphone;

[0093] The smart label placed in a -20±1℃ refrigerator was placed in a test chamber at 10±1℃ and -20±1℃ respectively, and the changes in the QR code were observed and recorded; the results are as follows: Figure 7 As shown, the results show that the two-dimensional code changes from blue-purple to colorless, and the two-dimensional code pattern is destroyed. When placed under low temperature again, the original two-dimensional code pattern will no longer appear, that is, the color change of the smart label of the present invention is irreversible.

[0094] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a smart label for frozen storage and transportation, characterized in that: The steps include: The sub-zero color-changing temperature-sensitive material is used as a printing solution, and a stamp is used to dip the printing solution and print it on wood pulp paper to form a QR code, thereby obtaining a smart label for frozen storage and transportation; The preparation method of the sub-zero color-changing temperature-sensitive material comprises the following steps: (1) mixing n-undecane and n-dodecanol uniformly to form a mixed solvent; Wherein, the volume percentage of n-undecane in the mixed solvent is 96%; (2) reacting a mixed solvent, crystal violet lactone, and bisphenol A to obtain a sub-zero color-changing temperature-sensitive material; The usage ratio of the mixed solvent, crystal violet lactone and bisphenol A is 10 mL: 100 mg: 100 mg.

2. The method according to claim 1, characterized in that The reaction in step (2) is carried out by stirring at 34-36° C. and 400-800 rpm for 12-48 hours.

3. The smart label for frozen storage and transportation prepared by the method according to claim 1.

4. A packaging material for frozen products, characterized in that: The smart label according to claim 3 is adopted.

5. Application of the smart label according to claim 3 in the field of frozen storage and transportation.

6. A method for detecting product quality during frozen transportation and storage, characterized in that: The smart label as described in claim 3 is adopted; the method is that during transportation and storage, the color of the smart label will change with the temperature. If the temperature is out of control, the QR code pattern will be destroyed. Even if it is subsequently reset to the specified temperature, the QR code will still not be recognizable, thereby being able to judge the temperature situation during storage; once the QR code pattern cannot be recognized by a smart phone, it is determined that the temperature is out of control.

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