Reversible temperature-variable thermosensitive express waybill for cold-chain logistics

Abstract

The invention discloses a reversible temperature-variable thermosensitive express waybill for cold-chain logistics, which comprises a base material layer and a composite thermosensitive coating coated on the surface of the base material layer, the base material layer is prepared from the following components in parts by mass: 30 to 45 parts of polyethylene-polylactic acid copolymer, 5 to 12 parts of modified nano montmorillonite, 10 to 18 parts of polybutylene adipate, 0.5 to 2 parts of antioxidant 1010 and 2 to 5 parts of plasticizer tributyl citrate; according to the invention, multiple innovative components are introduced to construct a composite thermosensitive coating system, so that reversible response to temperature change is realized, the color change cycle stability is excellent, temperature fluctuation in a cold-chain transportation process can be repeatedly monitored, and the defect of irreversible color change of an existing thermosensitive surface sheet is overcome; wherein the hydroxylated rare earth-organic ligand complex and the color former have a synergistic effect, so that the surface sheet presents obvious color change in different temperature intervals (for example, the surface sheet is dark blue at-18 DEG C or below, is light blue at 0-8 DEG C and is colorless at normal temperature), the temperature response sensitivity is high, and the color change response time is less than or equal to 5 seconds.

Description

Technical Field

[0001] This invention belongs to the field of cold chain logistics packaging and heat-sensitive materials technology, specifically a reversible temperature-sensitive heat-sensitive express waybill for cold chain logistics. Background Technology

[0002] Cold chain logistics is a crucial link in ensuring the quality of temperature-sensitive goods such as fresh food and pharmaceutical products. As the core identifier for the flow of goods, the express waybill not only needs to have basic information recording functions, but also needs to be able to intuitively reflect the temperature changes of goods during transportation so as to promptly detect abnormal temperature control issues.

[0003] Existing thermal express waybills are mostly irreversible color-changing types, which can only record single instances of temperature exceeding the limit and cannot achieve cyclical monitoring and traceability of temperature changes. Furthermore, the color-changing temperature range of conventional thermal materials is fixed, making it difficult to adapt to the temperature control requirements of different goods in cold chain logistics (such as refrigerated goods at 0-8℃ and frozen goods below -18℃). In addition, the existing thermal waybills have poor adhesion between the substrate and the thermal coating, making them prone to coating peeling and information blurring in humid cold chain environments. They also lack low-temperature resistance, easily becoming brittle and cracking at extreme low temperatures.

[0004] To address the aforementioned issues, there is an urgent need to develop a thermally sensitive express waybill specifically designed for cold chain logistics. This waybill features reversible temperature change capability, adaptability to multiple temperature control ranges, low-temperature and moisture resistance, and excellent adhesion. Based on this, this invention designs a novel composite thermally sensitive coating formula, introducing multiple innovative components to achieve reversible response and precise monitoring of temperature changes. Simultaneously, it optimizes the preparation processes of the substrate and coating, enhancing the overall weather resistance of the waybill.

[0005] Based on this, a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics is designed. Summary of the Invention

[0006] In view of the above situation and to overcome the defects of the prior art, the present invention provides a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics and its preparation method, which effectively solves the problems mentioned in the background.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics, comprising a substrate layer and a composite thermosensitive coating, wherein the composite thermosensitive coating is coated on the surface of the substrate layer, and the components are as follows by mass:

[0008] Substrate layer: 30-45 parts of polyethylene-polylactic acid copolymer, 5-12 parts of modified nano montmorillonite, 10-18 parts of polybutylene adipate, 0.5-2 parts of antioxidant 1010, and 2-5 parts of plasticizer tributyl citrate;

[0009] Composite thermosensitive coating: 2-6 parts of hydroxylated rare earth-organic ligand complex, 4-9 parts of polyamide-imide grafted thermosensitive polymer, 15-25 parts of modified fatty alcohol phase change microcapsules, 1-3 parts of sulfonated graphene / carbon black composite conductive particles, 1-4 parts of colorant 3-diethylamino-6-chlorofluorane, 10-18 parts of binder waterborne polyurethane, 0.8-2.5 parts of dispersant sodium dodecylbenzenesulfonate, and 30-50 parts of solvent deionized water.

[0010] Preferably, the preparation method of the hydroxylated rare earth-organic ligand complex is as follows:

[0011] Step 1: Raw material preparation. Weigh rare earth oxides, o-hydroxyphenylacetic acid, and sodium hydroxide in a mass ratio of 1:2.5-4.0:0.8-1.5. The amount of rare earth oxides is 5-10 grams, the amount of o-hydroxyphenylacetic acid is 12.5-40 grams, and the amount of sodium hydroxide is 4-15 grams. The rare earth oxides are selected from either lanthanum oxide or cerium oxide.

[0012] Step 2: Hydroxylation treatment. Rare earth oxides are added to a hydrochloric acid solution with a concentration of 2-5 mol / L. The amount of hydrochloric acid solution is 8-12 times the mass of the rare earth oxides. The reaction is carried out at a temperature of 60-80℃ and a stirring speed of 300-500 rpm for 2-3.5 hours. After the reaction is completed, the mixture is filtered and the filter residue is washed with deionized water until neutral to obtain hydroxylated rare earth salts.

[0013] Step 3: Coordination reaction. Add hydroxylated rare earth salt and o-hydroxyphenylacetic acid to the reaction vessel, add deionized water as solvent, the amount of solvent is 5-8 times the total mass of reactants, adjust the pH of the system to 5.5-7.0, and react at a constant temperature of 85-100℃ and a stirring speed of 400-600 rpm for 4-6 hours.

[0014] Step 4: Post-treatment. After the reaction is complete, the reaction solution is cooled to room temperature, and ethanol is added for precipitation. The amount of ethanol is 1.5-2.5 times the volume of the reaction solution. After filtration, the precipitate is placed in a vacuum drying oven and dried for 8-12 hours at a temperature of 60-80℃ and a vacuum degree of -0.08 to -0.06MPa. The precipitate is then ground through a 200-mesh sieve to obtain the hydroxylated rare earth-organic ligand complex.

[0015] Preferably, the polyamide-imide grafted thermosensitive polymer is prepared as follows:

[0016] Step 1: Raw material preparation: Weigh out 15-25 parts of 4,4'-diaminodiphenyl ether, 12-20 parts of pyromellitic dianhydride, 8-15 parts of N-isopropylacrylamide, 0.5-1.2 parts of benzoyl peroxide initiator, and 50-80 parts of N,N-dimethylformamide solvent according to the following mass proportions.

[0017] Step 2: Preparation of polyamide-imide prepolymer. 4,4'-diaminodiphenyl ether and N,N-dimethylformamide are added to a reaction vessel and stirred until dissolved under nitrogen protection, at a temperature of 25-35℃ and a stirring speed of 200-300 rpm. Then, pyromellitic dianhydride is slowly added, the temperature is raised to 60-75℃, and the reaction is continued for 3-5 hours to obtain the polyamide-imide prepolymer.

[0018] Step 3: Graft polymerization reaction. N-isopropylacrylamide and initiator benzoyl peroxide are added to the prepolymer solution. The reaction is carried out under nitrogen protection, at a temperature of 75-90℃ and a stirring speed of 350-500 rpm for 5-8 hours.

[0019] Step 4: Post-treatment. After the reaction is complete, the reaction solution is poured into deionized water for precipitation. The amount of deionized water is 3-5 times the volume of the reaction solution. The precipitate is collected by filtration and washed with ethanol 3-5 times. Then it is placed in a vacuum drying oven and dried for 12-16 hours at a temperature of 80-100℃ and a vacuum degree of -0.09 to -0.07MPa to obtain polyamide-imide grafted thermosensitive polymer.

[0020] Preferably, the modified fatty alcohol phase change microcapsules are prepared as follows:

[0021] Step 1: Core material preparation. Weigh hexadecyl alcohol, octadecyl alcohol, and dodecanol in a mass ratio of 3:1-2:0.5, with a total mass of 20-30 grams. Add them to a beaker and heat them to melt at a temperature of 50-65℃. Stir and mix them evenly to obtain the composite fatty alcohol core material.

[0022] Step 2: Preparation of wall material prepolymer. Weigh urea and 37% formaldehyde solution at a mass ratio of 1:1.2-1.8. The amount of urea is 8-15 grams and the amount of formaldehyde solution is 9.6-27 grams. Add them to the reaction vessel, add 20-30 grams of deionized water, adjust the pH value to 7.5-8.5, and stir and react for 1-2 hours at a temperature of 40-50℃ and a stirring speed of 250-350 rpm to obtain urea-formaldehyde resin prepolymer.

[0023] Step 3: Emulsification and dispersion. The composite fatty alcohol core material is added to a sodium dodecyl sulfate solution with a mass fraction of 2-5%. The amount of sodium dodecyl sulfate solution is 3-5 times the mass of the core material. Emulsification and dispersion are carried out at a temperature of 50-65℃ and a stirring speed of 600-800 rpm for 20-40 minutes to obtain a core material emulsion.

[0024] Step 4: Microencapsulation reaction. The urea-formaldehyde resin prepolymer is slowly added to the core material emulsion, the pH value is adjusted to 4.0-5.0, the temperature is raised to 60-75℃, and the reaction is carried out at a constant temperature for 3-5 hours under the condition of stirring speed of 400-600 rpm to form microcapsule wall material.

[0025] Step 5: Modification and post-treatment. Add 1-3% by mass of silane coupling agent KH550 to the reaction system, which is 0.5-1.5% of the mass of the microcapsules. Continue stirring for 1-2 hours. After the reaction is completed, cool to room temperature, filter and collect the microcapsules, wash with deionized water until neutral, and place in a forced-air drying oven to dry at 50-60℃ for 6-10 hours to obtain modified fatty alcohol phase change microcapsules.

[0026] Preferably, the preparation method of the sulfonated graphene / carbon black composite conductive particles is as follows:

[0027] Step 1: Raw material preparation. Weigh graphene and carbon black in a mass ratio of 1:2-3.5. The amount of graphene is 2-5 grams and the amount of carbon black is 4-17.5 grams. Separately take 20-40 ml of 98% concentrated sulfuric acid, 10-20 ml of 65% fuming nitric acid, and 5-10 ml of 30% hydrogen peroxide.

[0028] Step 2: Sulfonation treatment. Graphene is added to a mixed solution of concentrated sulfuric acid and fuming nitric acid, with a volume ratio of 2:1. The mixture is stirred at 30-50℃ and 300-400 rpm for 2-3 hours. Hydrogen peroxide is then slowly added, and the mixture is stirred for another 1-2 hours. After the reaction is complete, the reaction solution is poured into ice water, with the amount of ice water being 5-8 times the volume of the reaction solution. The residue is collected by filtration and washed with deionized water until neutral to obtain sulfonated graphene.

[0029] Step 3: Composite modification. Sulfonated graphene and carbon black are added to deionized water. The amount of deionized water is 10-15 times the total mass of the two. The mixture is ultrasonically dispersed evenly under ultrasonic power of 300-500 watts and ultrasonic time of 30-60 minutes. Then, the temperature is raised to 60-80℃ and the mixture is stirred and reacted for 2-4 hours at a stirring speed of 400-600 rpm.

[0030] Step 4: Post-processing. After the reaction is complete, filter and collect the product, place it in a vacuum drying oven, and dry it for 6-10 hours at a temperature of 70-90℃ and a vacuum degree of -0.08 to -0.06MPa. Grind it through a 300-mesh sieve to obtain sulfonated graphene / carbon black composite conductive particles.

[0031] Preferably, the preparation process of the express waybill includes the following steps:

[0032] Step 1: Preparation of the substrate layer. Polyethylene-polylactic acid copolymer, modified nano-montmorillonite, polybutylene adipate, antioxidant 1010 and plasticizer tributyl citrate are mixed in parts by mass and added to a twin-screw extruder. The mixture is melt-blended and extruded at a screw speed of 150-200 rpm and a temperature of 160-190℃. After calendering and cooling, a substrate layer with a thickness of 80-120 micrometers is obtained.

[0033] Step 2: Preparation of composite thermosensitive coating. Hydroxylated rare earth-organic ligand complex, polyamide-imide grafted thermosensitive polymer, modified fatty alcohol phase change microcapsules, sulfonated graphene / carbon black composite conductive particles, colorant, binder, dispersant, and solvent are mixed in parts by mass and stirred and dispersed at a stirring speed of 500-800 rpm for 30-60 minutes. Then, the mixture is ultrasonically dispersed evenly at an ultrasonic power of 400-600 watts for 20-40 minutes to obtain the coating slurry.

[0034] Step 3: Coating and drying. The coating slurry is applied to the surface of the substrate layer using a doctor blade coating method. The coating thickness is 15-30 micrometers. Then, it is placed in a forced-air drying oven and dried at a temperature of 60-80℃ for 30-60 minutes. Finally, it is cured with ultraviolet light at a wavelength of 365 nanometers for 3-5 minutes to obtain a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. This invention introduces a variety of innovative components to construct a composite thermosensitive coating system, achieving reversible response to temperature changes and excellent color-changing cycle stability. It can repeatedly monitor temperature fluctuations during cold chain transportation, solving the problem of irreversible color change in existing thermosensitive labels. Among them, the hydroxylated rare earth-organic ligand complex and the colorant work synergistically to make the label exhibit obvious color changes in different temperature ranges (e.g., dark blue below -18℃, light blue at 0-8℃, and colorless at room temperature), with high temperature response sensitivity and a color change response time ≤5 seconds.

[0037] 2. The polyamide-imide grafted thermosensitive polymer significantly improves the adhesion between the coating and the substrate layer, with a peel strength ≥3.5N / 10mm. At the same time, it optimizes the low-temperature resistance of the label, showing no cracking or coating peeling after being placed in a -30℃ low-temperature environment for 24 hours. The modified fatty alcohol phase change microcapsules can precisely control the color change temperature range by adjusting the ratio of composite fatty alcohols, adapting to the temperature control monitoring needs of different cold chain goods such as refrigerated and frozen goods.

[0038] 3. Sulfonated graphene / carbon black composite conductive particles improve the uniformity of electrical and thermal conductivity of the coating, avoiding the problem of local temperature response lag; the substrate layer is made of polyethylene-polylactic acid copolymer and modified nano-montmorillonite composite, which has both excellent flexibility and mechanical strength, with an elongation at break of ≥150%, and also has good biodegradability, meeting the requirements of green environmental protection.

[0039] 4. The preparation process of this invention is simple and controllable, the raw materials are readily available, and the production cost is low. The reversible temperature-sensitive thermosensitive express waybill prepared has excellent moisture resistance and abrasion resistance. It can maintain clear information and temperature monitoring function for a long time in the complex environment of cold chain logistics, and has broad application prospects. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics, comprising a substrate layer and a composite thermosensitive coating, wherein the composite thermosensitive coating is applied to the surface of the substrate layer, and the components are as follows by mass:

[0042] Substrate layer: 30-45 parts of polyethylene-polylactic acid copolymer, 5-12 parts of modified nano montmorillonite, 10-18 parts of polybutylene adipate, 0.5-2 parts of antioxidant 1010, and 2-5 parts of plasticizer tributyl citrate;

[0043] Composite thermosensitive coating: 2-6 parts of hydroxylated rare earth-organic ligand complex, 4-9 parts of polyamide-imide grafted thermosensitive polymer, 15-25 parts of modified fatty alcohol phase change microcapsules, 1-3 parts of sulfonated graphene / carbon black composite conductive particles, 1-4 parts of colorant 3-diethylamino-6-chlorofluorane, 10-18 parts of binder waterborne polyurethane, 0.8-2.5 parts of dispersant sodium dodecylbenzenesulfonate, and 30-50 parts of solvent deionized water.

[0044] The preparation method of the hydroxylated rare earth-organic ligand complex in this embodiment is as follows:

[0045] Step 1: Raw material preparation. Weigh rare earth oxides, o-hydroxyphenylacetic acid, and sodium hydroxide in a mass ratio of 1:2.5-4.0:0.8-1.5. The amount of rare earth oxides is 5-10 grams, the amount of o-hydroxyphenylacetic acid is 12.5-40 grams, and the amount of sodium hydroxide is 4-15 grams. The rare earth oxides are selected from either lanthanum oxide or cerium oxide.

[0046] Step 2: Hydroxylation treatment. Rare earth oxides are added to a hydrochloric acid solution with a concentration of 2-5 mol / L. The amount of hydrochloric acid solution is 8-12 times the mass of the rare earth oxides. The reaction is carried out at a temperature of 60-80℃ and a stirring speed of 300-500 rpm for 2-3.5 hours. After the reaction is completed, the mixture is filtered and the filter residue is washed with deionized water until neutral to obtain hydroxylated rare earth salts.

[0047] Step 3: Coordination reaction. Add hydroxylated rare earth salt and o-hydroxyphenylacetic acid to the reaction vessel, add deionized water as solvent, the amount of solvent is 5-8 times the total mass of reactants, adjust the pH of the system to 5.5-7.0, and react at a constant temperature of 85-100℃ and a stirring speed of 400-600 rpm for 4-6 hours.

[0048] Step 4: Post-treatment. After the reaction is complete, the reaction solution is cooled to room temperature, and ethanol is added for precipitation. The amount of ethanol is 1.5-2.5 times the volume of the reaction solution. After filtration, the precipitate is placed in a vacuum drying oven and dried for 8-12 hours at a temperature of 60-80℃ and a vacuum degree of -0.08 to -0.06MPa. The precipitate is then ground through a 200-mesh sieve to obtain the hydroxylated rare earth-organic ligand complex.

[0049] The preparation method of the polyamide-imide grafted thermosensitive polymer in this embodiment is as follows:

[0050] Step 1: Raw material preparation: Weigh out 15-25 parts of 4,4'-diaminodiphenyl ether, 12-20 parts of pyromellitic dianhydride, 8-15 parts of N-isopropylacrylamide, 0.5-1.2 parts of benzoyl peroxide initiator, and 50-80 parts of N,N-dimethylformamide solvent according to the following mass proportions.

[0051] Step 2: Preparation of polyamide-imide prepolymer. 4,4'-diaminodiphenyl ether and N,N-dimethylformamide are added to a reaction vessel and stirred until dissolved under nitrogen protection, at a temperature of 25-35℃ and a stirring speed of 200-300 rpm. Then, pyromellitic dianhydride is slowly added, the temperature is raised to 60-75℃, and the reaction is continued for 3-5 hours to obtain the polyamide-imide prepolymer.

[0052] Step 3: Graft polymerization reaction. N-isopropylacrylamide and initiator benzoyl peroxide are added to the prepolymer solution. The reaction is carried out under nitrogen protection, at a temperature of 75-90℃ and a stirring speed of 350-500 rpm for 5-8 hours.

[0053] Step 4: Post-treatment. After the reaction is complete, the reaction solution is poured into deionized water for precipitation. The amount of deionized water is 3-5 times the volume of the reaction solution. The precipitate is collected by filtration and washed with ethanol 3-5 times. Then it is placed in a vacuum drying oven and dried for 12-16 hours at a temperature of 80-100℃ and a vacuum degree of -0.09 to -0.07MPa to obtain polyamide-imide grafted thermosensitive polymer.

[0054] The preparation method of the modified fatty alcohol phase change microcapsules in this embodiment is as follows:

[0055] Step 1: Core material preparation. Weigh hexadecyl alcohol, octadecyl alcohol, and dodecanol in a mass ratio of 3:1-2:0.5, with a total mass of 20-30 grams. Add them to a beaker and heat them to melt at a temperature of 50-65℃. Stir and mix them evenly to obtain the composite fatty alcohol core material.

[0056] Step 2: Preparation of wall material prepolymer. Weigh urea and 37% formaldehyde solution at a mass ratio of 1:1.2-1.8. The amount of urea is 8-15 grams and the amount of formaldehyde solution is 9.6-27 grams. Add them to the reaction vessel, add 20-30 grams of deionized water, adjust the pH value to 7.5-8.5, and stir and react for 1-2 hours at a temperature of 40-50℃ and a stirring speed of 250-350 rpm to obtain urea-formaldehyde resin prepolymer.

[0057] Step 3: Emulsification and dispersion. The composite fatty alcohol core material is added to a sodium dodecyl sulfate solution with a mass fraction of 2-5%. The amount of sodium dodecyl sulfate solution is 3-5 times the mass of the core material. Emulsification and dispersion are carried out at a temperature of 50-65℃ and a stirring speed of 600-800 rpm for 20-40 minutes to obtain a core material emulsion.

[0058] Step 4: Microencapsulation reaction. The urea-formaldehyde resin prepolymer is slowly added to the core material emulsion, the pH value is adjusted to 4.0-5.0, the temperature is raised to 60-75℃, and the reaction is carried out at a constant temperature for 3-5 hours under the condition of stirring speed of 400-600 rpm to form microcapsule wall material.

[0059] Step 5: Modification and post-treatment. Add 1-3% by mass of silane coupling agent KH550 to the reaction system, which is 0.5-1.5% of the mass of the microcapsules. Continue stirring for 1-2 hours. After the reaction is completed, cool to room temperature, filter and collect the microcapsules, wash with deionized water until neutral, and place in a forced-air drying oven to dry at 50-60℃ for 6-10 hours to obtain modified fatty alcohol phase change microcapsules.

[0060] The preparation method of the sulfonated graphene / carbon black composite conductive particles in this embodiment is as follows:

[0061] Step 1: Raw material preparation. Weigh graphene and carbon black in a mass ratio of 1:2-3.5. The amount of graphene is 2-5 grams and the amount of carbon black is 4-17.5 grams. Separately take 20-40 ml of 98% concentrated sulfuric acid, 10-20 ml of 65% fuming nitric acid, and 5-10 ml of 30% hydrogen peroxide.

[0062] Step 2: Sulfonation treatment. Graphene is added to a mixed solution of concentrated sulfuric acid and fuming nitric acid, with a volume ratio of 2:1. The mixture is stirred at 30-50℃ and 300-400 rpm for 2-3 hours. Hydrogen peroxide is then slowly added, and the mixture is stirred for another 1-2 hours. After the reaction is complete, the reaction solution is poured into ice water, with the amount of ice water being 5-8 times the volume of the reaction solution. The residue is collected by filtration and washed with deionized water until neutral to obtain sulfonated graphene.

[0063] Step 3: Composite modification. Sulfonated graphene and carbon black are added to deionized water. The amount of deionized water is 10-15 times the total mass of the two. The mixture is ultrasonically dispersed evenly under ultrasonic power of 300-500 watts and ultrasonic time of 30-60 minutes. Then, the temperature is raised to 60-80℃ and the mixture is stirred and reacted for 2-4 hours at a stirring speed of 400-600 rpm.

[0064] Step 4: Post-processing. After the reaction is complete, filter and collect the product, place it in a vacuum drying oven, and dry it for 6-10 hours at a temperature of 70-90℃ and a vacuum degree of -0.08 to -0.06MPa. Grind it through a 300-mesh sieve to obtain sulfonated graphene / carbon black composite conductive particles.

[0065] The preparation process of the express waybill in this embodiment includes the following steps:

[0066] Step 1: Preparation of the substrate layer. Polyethylene-polylactic acid copolymer, modified nano-montmorillonite, polybutylene adipate, antioxidant 1010 and plasticizer tributyl citrate are mixed in parts by mass and added to a twin-screw extruder. The mixture is melt-blended and extruded at a screw speed of 150-200 rpm and a temperature of 160-190℃. After calendering and cooling, a substrate layer with a thickness of 80-120 micrometers is obtained.

[0067] Step 2: Preparation of composite thermosensitive coating. Hydroxylated rare earth-organic ligand complex, polyamide-imide grafted thermosensitive polymer, modified fatty alcohol phase change microcapsules, sulfonated graphene / carbon black composite conductive particles, colorant, binder, dispersant, and solvent are mixed in parts by mass and stirred and dispersed at a stirring speed of 500-800 rpm for 30-60 minutes. Then, the mixture is ultrasonically dispersed evenly at an ultrasonic power of 400-600 watts for 20-40 minutes to obtain the coating slurry.

[0068] Step 3: Coating and drying. The coating slurry is applied to the surface of the substrate layer using a doctor blade coating method. The coating thickness is 15-30 micrometers. Then, it is placed in a forced-air drying oven and dried at a temperature of 60-80℃ for 30-60 minutes. Finally, it is cured with ultraviolet light at a wavelength of 365 nanometers for 3-5 minutes to obtain a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics.

[0069] Example 1:

[0070] A reversible temperature-sensitive thermosensitive express waybill for cold chain logistics, the components of which are as follows by mass:

[0071] Substrate layer: 35 parts polyethylene-polylactic acid copolymer, 8 parts modified nano montmorillonite, 14 parts polybutylene adipate, 1 part antioxidant 1010, and 3 parts plasticizer tributyl citrate.

[0072] Composite thermosensitive coating: 4 parts hydroxylated rare earth-organic ligand complex, 6 parts polyamide-imide grafted thermosensitive polymer, 20 parts modified fatty alcohol phase change microcapsules, 2 parts sulfonated graphene / carbon black composite conductive particles, 2 parts colorant 3-diethylamino-6-chlorofluorane, 14 parts waterborne polyurethane binder, 1.5 parts dispersant sodium dodecylbenzenesulfonate, and 40 parts solvent deionized water.

[0073] Preparation of hydroxylated rare earth-organic ligand complexes: Weigh 7 g of lanthanum oxide, 21 g of o-hydroxyphenylacetic acid, and 7 g of sodium hydroxide; add lanthanum oxide to 35 g of 2 mol / L hydrochloric acid solution, stir at 65 °C and 400 rpm for 2.5 hours, filter and wash until neutral; add hydroxylated rare earth salt and o-hydroxyphenylacetic acid to 140 g of deionized water, adjust the pH to 6.0, and react at 90 °C and 500 rpm for 5 hours; after cooling, add 210 mL of ethanol to precipitate, filter, dry under vacuum at 65 °C and -0.07 MPa for 10 hours, and grind through a 200 mesh sieve.

[0074] Preparation of polyamide-imide grafted thermosensitive polymer: Weigh 20 parts of 4,4'-diaminodiphenyl ether, 16 parts of pyromellitic dianhydride, 12 parts of N-isopropylacrylamide, 0.8 parts of benzoyl peroxide initiator, and 65 parts of N,N-dimethylformamide solvent; dissolve 4,4'-diaminodiphenyl ether and N,N-dimethylformamide under nitrogen protection, 30℃, and 250 rpm; add pyromellitic dianhydride and heat to 70℃ for 4 hours; add N-isopropylacrylamide and initiator, and react at 80℃ and 400 rpm for 6 hours; precipitate in 260 parts of deionized water, wash 4 times with ethanol, and dry under vacuum at 90℃ and -0.08 MPa for 14 hours.

[0075] Preparation of modified fatty alcohol phase change microcapsules: Weigh 15g of hexadecyl alcohol, 10g of octadecyl alcohol, and 5g of dodecanol, and melt mix them at 55℃; weigh 12g of urea and 18g of 37% formaldehyde solution, add 25g of deionized water, adjust the pH to 8.0, and react at 45℃ and 300 rpm for 1.5 hours to obtain a prepolymer; add the core material to 120g of 3% sodium dodecyl sulfate solution, and emulsify at 60℃ and 700 rpm for 30 minutes; add the prepolymer, adjust the pH to 4.5, and react at 70℃ and 500 rpm for 4 hours; add 0.3g of silane coupling agent KH550, and continue the reaction for 1.5 hours; cool and filter, wash until neutral, and dry at 55℃ for 8 hours.

[0076] Preparation of sulfonated graphene / carbon black composite conductive particles: Weigh 3 g of graphene and 8 g of carbon black; add graphene to a mixed solution of 30 mL concentrated sulfuric acid and 15 mL fuming nitric acid, react at 40 °C and 350 rpm for 2.5 hours, add 8 mL of hydrogen peroxide and continue the reaction for 1.5 hours; pour into 225 mL of ice water, filter and wash until neutral; add sulfonated graphene and carbon black to 110 g of deionized water, sonicate at 400 W for 45 minutes, react at 70 °C and 500 rpm for 3 hours; filter, dry under vacuum at 80 °C and -0.07 MPa for 8 hours, and grind through a 300 mesh sieve.

[0077] Express waybill preparation: The substrate layer components are added to a twin-screw extruder and melt-blended and extruded at 170°C and 180 rpm, and calendered to obtain a 100-micron substrate layer; the coating components are mixed, stirred at 600 rpm for 45 minutes, and ultrasonically sonicated at 500 watts for 30 minutes to obtain a slurry; the thickness is 20 microns with a doctor blade coating, dried at 70°C for 45 minutes, and cured with 365 nm ultraviolet light for 4 minutes to obtain the finished product.

[0078] Testing revealed that the finished product is dark blue below -18℃, light blue between 0-8℃, and colorless at 25℃, with a color change response time of 3 seconds. After 50 cycles of color change, the color contrast remains ≥90%. It shows no cracking after being placed at -30℃ for 24 hours, has a coating peel strength of 4.2N / 10mm, withstands ≥50 abrasion cycles, and exhibits excellent moisture resistance, with no coating peeling and clear, unblurred information after 72 hours in an environment with 82% relative humidity.

[0079] Example 2

[0080] A reversible temperature-sensitive thermosensitive express waybill for cold chain logistics, the components of which are as follows by mass:

[0081] Substrate layer: 40 parts of polyethylene-polylactic acid copolymer, 10 parts of modified nano montmorillonite, 16 parts of polybutylene adipate, 1.5 parts of antioxidant 1010, and 4 parts of plasticizer tributyl citrate;

[0082] Composite thermosensitive coating: 5 parts hydroxylated rare earth-organic ligand complex, 8 parts polyamide-imide grafted thermosensitive polymer, 23 parts modified fatty alcohol phase change microcapsules, 2.5 parts sulfonated graphene / carbon black composite conductive particles, 3 parts colorant 3-diethylamino-6-chlorofluorane, 16 parts binder waterborne polyurethane, 2 parts dispersant sodium dodecylbenzenesulfonate, and 45 parts solvent deionized water.

[0083] Preparation of hydroxylated rare earth-organic ligand complexes: Weigh 8 g of cerium oxide, 28 g of o-hydroxyphenylacetic acid, and 9.6 g of sodium hydroxide; add cerium oxide to 64 g of 3 mol / L hydrochloric acid solution, stir at 70 °C and 450 rpm for 3 hours, filter and wash until neutral; add hydroxylated rare earth salt and o-hydroxyphenylacetic acid to 182.4 g of deionized water, adjust the pH to 6.5, and react at 95 °C and 550 rpm for 5.5 hours; after cooling, add 273.6 mL of ethanol to precipitate, filter, dry under vacuum at 70 °C and -0.07 MPa for 11 hours, and grind through a 200-mesh sieve.

[0084] Preparation of polyamide-imide grafted thermosensitive polymer: Weigh 25 parts of 4,4'-diaminodiphenyl ether, 20 parts of pyromellitic dianhydride, 15 parts of N-isopropylacrylamide, 1.2 parts of benzoyl peroxide initiator, and 80 parts of N,N-dimethylformamide solvent; dissolve 4,4'-diaminodiphenyl ether and N,N-dimethylformamide under nitrogen protection, 35℃, and 300 rpm; add pyromellitic dianhydride and heat to 75℃ for 5 hours; add N-isopropylacrylamide and initiator, and react at 85℃ and 450 rpm for 7 hours; precipitate in 320 parts of deionized water, wash 5 times with ethanol, and dry under vacuum at 95℃ and -0.08 MPa for 15 hours.

[0085] Preparation of modified fatty alcohol phase change microcapsules: Weigh 18g of hexadecyl alcohol, 12g of octadecyl alcohol, and 6g of dodecanol, and melt mix them at 60℃; weigh 15g of urea and 24g of 37% formaldehyde solution, add 30g of deionized water, adjust the pH to 8.2, and react at 48℃ and 350 rpm for 1.8 hours to obtain a prepolymer; add the core material to 168g of 4% sodium dodecyl sulfate solution, and emulsify at 65℃ and 750 rpm for 35 minutes; add the prepolymer, adjust the pH to 4.8, and react at 75℃ and 550 rpm for 4.5 hours; add 0.5g of silane coupling agent KH550, and continue the reaction for 1.8 hours; cool and filter, wash until neutral, and dry at 58℃ for 9 hours.

[0086] Preparation of sulfonated graphene / carbon black composite conductive particles: Weigh 4 g of graphene and 12 g of carbon black; add graphene to a mixed solution of 36 mL concentrated sulfuric acid and 18 mL fuming nitric acid, react at 45 °C and 380 rpm for 2.8 h, add 9 mL of hydrogen peroxide and continue the reaction for 1.8 h; pour into 261 mL of ice water, filter and wash until neutral; add sulfonated graphene and carbon black to 160 g of deionized water, sonicate at 450 W for 50 min, react at 75 °C and 550 rpm for 3.5 h; filter, dry under vacuum at 85 °C and -0.07 MPa for 9 h, and grind through a 300 mesh sieve.

[0087] Express waybill preparation: The substrate layer components are added to a twin-screw extruder and melt-blended and extruded at 180°C and 190 rpm, and calendered to obtain a 110-micron substrate layer; the coating components are mixed, stirred at 700 rpm for 50 minutes, and ultrasonically sonicated at 550 watts for 35 minutes to obtain a slurry; a doctor blade coating with a thickness of 25 microns is applied, dried at 75°C for 50 minutes, and cured with 365 nm UV for 4.5 minutes to obtain the finished product.

[0088] Testing revealed that the finished product is dark blue below -18℃, light blue between 0-8℃, and colorless at 25℃. The color change response time is 2.5 seconds, and the color contrast is ≥92% after 50 color changes. It exhibits stable performance at -30℃, with a coating peel strength of 4.5N / 10mm. It also demonstrates excellent moisture resistance, showing no coating peeling and maintaining clear information even after 72 hours of exposure to 85% relative humidity.

[0089] Example 3

[0090] A reversible temperature-sensitive thermosensitive express waybill for cold chain logistics, the components of which are as follows by mass:

[0091] Substrate layer: 30 parts polyethylene-polylactic acid copolymer, 5 parts modified nano montmorillonite, 10 parts polybutylene adipate, 0.5 parts antioxidant 1010, and 2 parts plasticizer tributyl citrate;

[0092] Composite thermosensitive coating: 2 parts hydroxylated rare earth-organic ligand complex, 4 parts polyamide-imide grafted thermosensitive polymer, 15 parts modified fatty alcohol phase change microcapsules, 1 part sulfonated graphene / carbon black composite conductive particles, 1 part colorant 3-diethylamino-6-chlorofluorane, 10 parts binder waterborne polyurethane, 0.8 parts dispersant sodium dodecylbenzenesulfonate, and 30 parts solvent deionized water.

[0093] Preparation of hydroxylated rare earth-organic ligand complexes: Weigh 5 g of lanthanum oxide, 12.5 g of o-hydroxyphenylacetic acid, and 4 g of sodium hydroxide; add lanthanum oxide to 40 g of 2 mol / L hydrochloric acid solution, stir at 60 °C and 300 rpm for 2 hours, filter and wash until neutral; add hydroxylated rare earth salt and o-hydroxyphenylacetic acid to 87.5 g of deionized water, adjust the pH to 5.5, and react at 85 °C and 400 rpm for 4 hours; after cooling, add 131.25 mL of ethanol to precipitate, filter, dry under vacuum at 60 °C and -0.06 MPa for 8 hours, and grind through a 200-mesh sieve.

[0094] Preparation of polyamide-imide grafted thermosensitive polymer: Weigh 15 parts of 4,4'-diaminodiphenyl ether, 12 parts of pyromellitic dianhydride, 8 parts of N-isopropylacrylamide, 0.5 parts of benzoyl peroxide initiator, and 50 parts of N,N-dimethylformamide solvent; dissolve 4,4'-diaminodiphenyl ether and N,N-dimethylformamide under nitrogen protection, 25℃, and 200 rpm; add pyromellitic dianhydride and heat to 60℃ for 3 hours; add N-isopropylacrylamide and initiator, and react at 75℃ and 350 rpm for 5 hours; precipitate in 150 parts of deionized water, wash 3 times with ethanol, and dry under vacuum at 80℃ and -0.07 MPa for 12 hours.

[0095] Preparation of modified fatty alcohol phase change microcapsules: Weigh 12g of hexadecyl alcohol, 4g of octadecyl alcohol, and 2g of dodecanol, and melt mix them at 50℃; weigh 8g of urea and 9.6g of 37% formaldehyde solution, add 20g of deionized water, adjust the pH to 7.5, and react at 40℃ and 250 rpm for 1 hour to obtain a prepolymer; add the core material to 54g of 2% sodium dodecyl sulfate solution, and emulsify at 50℃ and 600 rpm for 20 minutes; add the prepolymer, adjust the pH to 4.0, and react at 60℃ and 400 rpm for 3 hours; add 0.1g of silane coupling agent KH550, and continue the reaction for 1 hour; cool and filter, wash until neutral, and dry at 50℃ for 6 hours.

[0096] Preparation of sulfonated graphene / carbon black composite conductive particles: Weigh 2 g of graphene and 4 g of carbon black; add graphene to a mixed solution of 20 mL concentrated sulfuric acid and 10 mL fuming nitric acid, react at 30 °C and 300 rpm for 2 hours, add 5 mL of hydrogen peroxide and continue the reaction for 1 hour; pour into 150 mL of ice water, filter and wash until neutral; add sulfonated graphene and carbon black to 60 g of deionized water, sonicate at 300 W for 30 minutes, react at 60 °C and 400 rpm for 2 hours; filter, dry under vacuum at 70 °C and -0.06 MPa for 6 hours, and grind through a 300 mesh sieve.

[0097] Express waybill preparation: The substrate layer components are added to a twin-screw extruder and melt-blended and extruded at 160°C and 150 rpm, and calendered to obtain an 80-micron substrate layer; the coating components are mixed, stirred at 500 rpm for 30 minutes, and ultrasonically sonicated at 400 watts for 20 minutes to obtain a slurry; the thickness is 15 microns with a doctor blade coating, dried at 60°C for 30 minutes, and cured with 365 nm ultraviolet light for 3 minutes to obtain the finished product.

[0098] Testing revealed that the finished product is dark blue below -18℃, light blue between 0-8℃, and colorless at 25℃, with a color change response time of 5 seconds. After 50 cycles of color change, the color contrast is ≥88%. It does not crack after being placed at -30℃ for 24 hours, has a coating peel strength of 3.5N / 10mm, withstands ≥45 abrasion cycles, and retains clear information after being placed in an environment with 80% relative humidity for 72 hours.

[0099] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A reversible temperature change type heat sensitive express sheet for cold chain logistics, characterized by, The composite heat-sensitive coating is coated on the surface of the substrate layer, and the components are as follows in parts by mass: The substrate layer: polyethylene-poly-lactic acid copolymer 30-45 parts, modified nano montmorillonite 5-12 parts, polybutylene adipate 10-18 parts, antioxidant 1010 0.5-2 parts, plasticizer tributyl citrate 2-5 parts; The composite heat-sensitive coating: hydroxylated rare earth-organic ligand complex 2-6 parts, polyamide-imide grafted temperature-sensitive polymer 4-9 parts, modified fatty alcohol phase change microcapsule 15-25 parts, sulfonated graphene / carbon black composite conductive particle 1-3 parts, color former 3-diethylamino-6-chlorofluoran 1-4 parts, binder water-based polyurethane 10-18 parts, dispersant sodium dodecyl benzene sulfonate 0.8-2.5 parts, solvent deionized water 30-50 parts.

2. The reversible temperature change heat-sensitive express label for cold chain logistics according to claim 1, characterized in that, The preparation method of the hydroxylated rare earth-organic ligand complex is as follows: Step 1: raw material preparation, the raw materials are weighed according to the mass ratio of 1:2.5-4.0:0.8-1.5, wherein the rare earth oxide is 5-10 grams, the o-hydroxyphenylacetic acid is 12.5-40 grams, and the sodium hydroxide is 4-15 grams; the rare earth oxide is selected from one of lanthanum oxide or cerium oxide; Step 2: hydroxylation treatment, the rare earth oxide is added into a hydrochloric acid solution with a concentration of 2-5 mol / L, the amount of the hydrochloric acid solution is 8-12 times the mass of the rare earth oxide, and the reaction is stirred at a stirring speed of 300-500 revolutions per minute for 2-3.5 hours at a temperature of 60-80°C; after the reaction is completed, the filter residue is washed with deionized water until it is neutral, and a hydroxylated rare earth salt is obtained; Step 3: coordination reaction, the hydroxylated rare earth salt and the o-hydroxyphenylacetic acid are added into a reaction kettle, deionized water is added as a solvent, the amount of the solvent is 5-8 times the total mass of the reactants, the pH value of the system is adjusted to 5.5-7.0, and the reaction is carried out at a temperature of 85-100°C and a stirring speed of 400-600 revolutions per minute for 4-6 hours; Step 4: post-treatment, after the reaction is completed, the reaction liquid is cooled to room temperature, ethanol is added for precipitation, the amount of the ethanol is 1.5-2.5 times the volume of the reaction liquid, the precipitate is filtered, and then placed in a vacuum drying oven for drying at a temperature of 60-80°C and a vacuum degree of -0.08 to -0.06 MPa for 8-12 hours; the precipitate is ground through a 200-mesh sieve to obtain the hydroxylated rare earth-organic ligand complex.

3. The reversible temperature change heat-sensitive express label for cold chain logistics according to claim 1, characterized in that, The preparation method of the polyamide-imide grafted temperature-sensitive polymer is as follows: Step 1: raw material preparation, 4,4'-diamino diphenyl ether 15-25 parts, pyromellitic dianhydride 12-20 parts, N-isopropyl acrylamide 8-15 parts, initiator dibenzoyl peroxide 0.5-1.2 parts, and solvent N,N-dimethylformamide 50-80 parts are weighed in parts by mass; Step 2: Preparation of polyamide-imide prepolymer, 4,4'-diamino diphenyl ether and N,N-dimethylformamide were added to a reaction kettle, and stirred and dissolved under the conditions of nitrogen protection, temperature 25-35℃, stirring speed 200-300r / min, then uniform tetracarboxylic acid dianhydride was slowly added, the temperature was raised to 60-75℃, and the stirring reaction was continued for 3-5 hours to obtain a polyamide-imide prepolymer; Step 3: Graft polymerization, N-isopropyl acrylamide and initiator dibenzoyl peroxide were added to the prepolymer solution, and constant temperature reaction was carried out under the conditions of nitrogen protection, temperature 75-90℃, stirring speed 350-500r / min for 5-8 hours; Step 4: Post-treatment, after the reaction was completed, the reaction solution was poured into deionized water for precipitation, the amount of deionized water was 3-5 times the volume of the reaction solution, the precipitate was collected by filtration, washed with ethanol for 3-5 times, then placed in a vacuum drying oven, dried under the conditions of temperature 80-100℃, vacuum degree-0.09 to-0.07MPa for 12-16 hours to obtain a polyamide-imide grafted temperature-sensitive polymer.

4. The reversible temperature change heat-sensitive express label for cold chain logistics according to claim 1, characterized in that, The preparation method of the modified fatty alcohol phase change microcapsule is as follows: Step 1: Core material preparation, hexadecanol, octadecanol and dodecanol were weighed according to the mass ratio of 3:1-2:0.5, the total mass was 20-30g, and were added to a beaker, heated and melted under the condition of temperature 50-65℃, and stirred and mixed uniformly to obtain a composite fatty alcohol core material; Step 2: Preparation of wall material prepolymer, urea and formaldehyde solution with a mass fraction of 37% were weighed according to the mass ratio of 1:1.2-1.8, the amount of urea was 8-15g, the amount of formaldehyde solution was 9.6-27g, deionized water 20-30g was added to a reaction kettle, the pH value was adjusted to 7.5-8.5, and stirring reaction was carried out under the conditions of temperature 40-50℃, stirring speed 250-350r / min for 1-2 hours to obtain a urea-formaldehyde resin prepolymer; Step 3: Emulsification and dispersion, the composite fatty alcohol core material was added to a sodium dodecyl sulfate solution with a mass fraction of 2-5%, the amount of sodium dodecyl sulfate solution was 3-5 times the mass of the core material, and emulsification and dispersion were carried out under the conditions of temperature 50-65℃, stirring speed 600-800r / min for 20-40 minutes to obtain a core material emulsion; Step 4: Microcapsulation reaction, the urea-formaldehyde resin prepolymer was slowly added to the core material emulsion, the pH value was adjusted to 4.0-5.0, the temperature was raised to 60-75℃, and constant temperature reaction was carried out under the conditions of stirring speed 400-600r / min for 3-5 hours to form a microcapsule wall material; Step 5: Modification and post-treatment, silane coupling agent KH550 with a mass fraction of 1-3% was added to the reaction system, the amount was 0.5-1.5% of the mass of the microcapsule, and stirring reaction was continued for 1-2 hours, then the reaction was cooled to room temperature, the microcapsule was collected by filtration, washed with deionized water until neutral, and placed in a blowing drying oven, dried under the condition of temperature 50-60℃ for 6-10 hours to obtain a modified fatty alcohol phase change microcapsule.

5. The reversible temperature change heat-sensitive express label for cold chain logistics according to claim 1, characterized in that, The preparation method of the sulfonated graphene / carbon black composite conductive particle is as follows: Step 1: Raw material preparation. Weigh graphene and carbon black in a mass ratio of 1:2-3.

5. The amount of graphene is 2-5 grams and the amount of carbon black is 4-17.5 grams. Separately take 20-40 ml of 98% concentrated sulfuric acid, 10-20 ml of 65% fuming nitric acid, and 5-10 ml of 30% hydrogen peroxide. Step 2: Sulfonation treatment. Graphene is added to a mixed solution of concentrated sulfuric acid and fuming nitric acid, with a volume ratio of 2:

1. The mixture is stirred at 30-50℃ and 300-400 rpm for 2-3 hours. Hydrogen peroxide is then slowly added, and the mixture is stirred for another 1-2 hours. After the reaction is complete, the reaction solution is poured into ice water, with the amount of ice water being 5-8 times the volume of the reaction solution. The residue is collected by filtration and washed with deionized water until neutral to obtain sulfonated graphene. Step 3: Composite modification. Sulfonated graphene and carbon black are added to deionized water. The amount of deionized water is 10-15 times the total mass of the two. The mixture is ultrasonically dispersed evenly under ultrasonic power of 300-500 watts and ultrasonic time of 30-60 minutes. Then, the temperature is raised to 60-80℃ and the mixture is stirred and reacted for 2-4 hours at a stirring speed of 400-600 rpm. Step 4: Post-processing. After the reaction is complete, filter and collect the product, place it in a vacuum drying oven, and dry it for 6-10 hours at a temperature of 70-90℃ and a vacuum degree of -0.08 to -0.06MPa. Grind it through a 300-mesh sieve to obtain sulfonated graphene / carbon black composite conductive particles.

6. The reversible temperature change heat-sensitive express label for cold chain logistics according to claim 1, characterized in that, The preparation process of the express waybill includes the following steps: Step 1: Preparation of the substrate layer. Polyethylene-polylactic acid copolymer, modified nano-montmorillonite, polybutylene adipate, antioxidant 1010 and plasticizer tributyl citrate are mixed in parts by mass and added to a twin-screw extruder. The mixture is melt-blended and extruded at a screw speed of 150-200 rpm and a temperature of 160-190℃. After calendering and cooling, a substrate layer with a thickness of 80-120 micrometers is obtained. Step 2: Preparation of composite thermosensitive coating. Hydroxylated rare earth-organic ligand complex, polyamide-imide grafted thermosensitive polymer, modified fatty alcohol phase change microcapsules, sulfonated graphene / carbon black composite conductive particles, colorant, binder, dispersant, and solvent are mixed in parts by mass and stirred and dispersed at a stirring speed of 500-800 rpm for 30-60 minutes. Then, the mixture is ultrasonically dispersed evenly at an ultrasonic power of 400-600 watts for 20-40 minutes to obtain the coating slurry. Step 3: Coating and drying. The coating slurry is applied to the surface of the substrate layer using a doctor blade coating method. The coating thickness is 15-30 micrometers. Then, it is placed in a forced-air drying oven and dried at a temperature of 60-80℃ for 30-60 minutes. Finally, it is cured with ultraviolet light at a wavelength of 365 nanometers for 3-5 minutes to obtain a reversible temperature-sensitive thermosensitive express waybill for cold chain logistics.