Multifunctional medical dry heat-sensitive film and preparation method thereof

Abstract

This invention provides a multifunctional medical dry thermal film and its preparation method, belonging to the technical field of thermal film. This application employs an iron / copper berghehendate and a highly sterically hindered polyphenol ligand to form a solid-phase coordination colorimetric system. The metal source and ligand are fixed as submicron particles in a polymer matrix, softening, diffusing, and undergoing coordination colorimetry under heating by a thermal head. Unheated areas remain inert, which helps to reduce spontaneous color development at room temperature and bottom haze caused by thermal diffusion, thus controlling the grayscale heating history. Lanthanum hexaboride nanoparticles are added to the colorimetric layer for near-infrared photothermal conversion, improving temperature rise efficiency while maintaining transmittance. The barrier coating on the back, the antistatic back coating, and the UV-cured matte protective layer on the front work together to regulate moisture, static electricity, and surface friction, balancing film transport stability and writeability. An upconversion luminescent nanoparticle layer is locally set at the edge of the substrate, providing anti-counterfeiting luminescent markings upon near-infrared excitation, balancing anti-counterfeiting identification and imaging performance.

Description

Technical Field

[0001] This invention belongs to the field of thermal film technology, and relates to a multifunctional medical dry thermal film and its preparation method. Background Technology

[0002] Medical dry imaging technology, due to its advantages such as no need for wet chemical processing, no waste liquid generation, and fast imaging speed, has been widely used in the output of medical images such as CT, MRI, and CR / DR. Currently, medical dry films are mainly divided into two technical routes: dry silver halide technology and dry non-silver halide thermal technology. Although dry silver halide films have extremely high blackness and excellent image quality, the core raw material silver is expensive, and these films usually contain a large amount of organic reducing agents, often involving the use of organic solvents in the production process. This not only increases production costs and environmental pressure, but the scarcity of silver resources also limits its further cost-effective promotion. To reduce costs and environmental burden, non-silver halide medical thermal films based on a "colorless dye-developer" system have emerged. However, this type of film has inherent drawbacks.

[0003] The reaction between colorless dyes and chromogenic agents is typically a reversible reaction based on the gain and loss of electrons in an acid-base relationship. During long-term storage, exposure to light, high temperature, high humidity, or chemical reagents (such as alcohol or adhesive tape) can easily damage the chromogenic structure, leading to image fading or yellowing of the background due to oxidation. This is a fatal flaw for medical diagnostic images requiring preservation for 10-30 years (especially for oncology and orthopedic images where disease progression needs to be traced). Secondly, traditional non-silver halide thermosensitive materials are prone to severe "thermal fog" under high temperature and humidity conditions, resulting in decreased image contrast and affecting the accuracy of diagnosis. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a multifunctional medical dry thermal film and its preparation method. This application utilizes a solid-phase coordination colorimetric system of iron / copper berghehendate metal soap and highly sterically hindered polyphenol ligands. The metal source and ligands are respectively fixed as submicron solid particles, which soften, diffuse, and coordinate colorimetrically during heating by the thermal head, thus reducing spontaneous color development at room temperature and thermal diffusion halos. A small amount of lanthanum hexaboride photothermal particles is incorporated to improve local temperature rise and imaging sensitivity while maintaining transmittance. The back side employs a highly cross-linked acrylic barrier layer and a mesoporous silica / PEDOT:PSS functional layer, while the front side is superimposed with a UV-cured matte protective layer. This layered control of factors such as moisture, static electricity, and mechanical scratches improves film transport stability and the feel of writing and reading the film. Simultaneously, an upconversion luminescent nanoparticle layer is introduced locally at the edge of the substrate to achieve an optical anti-counterfeiting mark relatively independent of the main imaging area. The combination of the aforementioned color development mechanism and multilayer structure enables this application to form a technical route that differs from traditional silver halide films and conventional thermal recording materials in terms of imaging control, environmental adaptability, and functional integration in a silver-free thermal system.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a multifunctional medical dry thermal film, the method comprising:

[0007] S1: Add behenic acid to deionized water, add sodium hydroxide solution dropwise to react and obtain sodium behenic acid solution, adjust the pH with hydrochloric acid to obtain reaction solution A, add mixed metal solution dropwise, stir to react, filter, wash and dry to obtain iron / copper behenic acid complex; mix iron / copper behenic acid complex with polyvinyl alcohol aqueous solution to obtain dispersion, grind and disperse in a sand mill, add deionized water during grinding to obtain aqueous metal source dispersion;

[0008] S2: Gallic acid and octadecylamine are added to a mixed solvent, and dicyclohexylcarbodiimide is added as a catalyst to obtain reaction solution B. The reaction is stirred, filtered while hot, rotary evaporated, and recrystallized to obtain the modified ligand. The modified ligand is mixed with ethanol, and then styrene-acrylic acid copolymer emulsion is added. Deionized water is added to adjust the solid content to obtain a pre-grinding solution, which is placed in a bead mill for wet grinding to obtain an aqueous high steric hindrance ligand dispersion.

[0009] S3: Rare earth chlorides are added to the second mixed solvent, and nitrogen gas is used to purge water. A methanol solution containing ammonium fluoride and sodium hydroxide is added under a nitrogen atmosphere to obtain reaction solution C. The reaction is heated, cooled, centrifuged, and washed to obtain oil-soluble upconversion luminescent nanoparticles. The oil-soluble upconversion luminescent nanoparticles and DSPE-PEG2000 are dispersed in chloroform, and chloroform is removed by rotary evaporation to form a film. Deionized water is added and ultrasonically hydrated in a water bath to obtain an aqueous upconversion luminescent nanoparticle dispersion. Lanthanum hexaboride nanoparticles are added to a sodium polyacrylate solution and ultrasonically crushed under ice-water bath conditions to obtain a photothermal conversion dispersion.

[0010] S4: Prepare a highly cross-linked acrylic resin emulsion as a barrier primer; mix mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion and waterborne polyurethane resin, and degas by ultrasonication to obtain a functional back coating; mix waterborne metal source dispersion with waterborne high steric hindrance ligand dispersion, add photothermal conversion dispersion and leveling agent, stir and mix evenly to obtain a color development layer coating; mix waterborne UV-curable polyurethane acrylate emulsion with PMMA cross-linked microspheres, add Irgacure2959 photoinitiator, and adjust the solid content to obtain a top protective liquid;

[0011] S5: Apply a barrier primer to the back of a blue PET substrate and dry it. Then apply a functional back coating and dry it. Apply an aqueous upconversion luminescent nanoparticle dispersion to a preset area on the front edge of the substrate and dry it. Then apply a color development layer coating to the entire front of the substrate, pre-dry and finally dry it. Finally, apply a top protective liquid on the color development layer and dry it. Then cure it in a UV lamp box and roll it up to obtain a multifunctional medical dry thermal film.

[0012] As a preferred technical solution of the present invention, in step S1, the mass ratio of behenic acid to deionized water is 1:(5-10), for example, it can be 1:5.0, 1:5.5, 1:6.0, 1:6.5, 1:7.0, 1:7.5, 1:8.0, 1:8.5, 1:9.0, 1:9.5 or 1:10.0, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] In some optional embodiments, the temperature of the deionized water is 75-90°C, for example, it can be 75.0°C, 76.5°C, 78.0°C, 79.5°C, 81.0°C, 82.5°C, 84.0°C, 85.5°C, 87.0°C, 88.5°C or 90.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0014] In some alternative embodiments, the concentration of the sodium hydroxide solution is 1-3M, for example, it can be 1.0M, 1.2M, 1.4M, 1.6M, 1.8M, 2.0M, 2.2M, 2.4M, 2.6M, 2.8M or 3.0M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0015] In some alternative embodiments, the reaction time after adding sodium hydroxide solution is 1-2 hours, for example, 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, or 2.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0016] In some optional embodiments, the molar ratio of sodium hydroxide to behenic acid is (1-1.2):1, for example, it can be 1.00:1, 1.02:1, 1.04:1, 1.06:1, 1.08:1, 1.10:1, 1.12:1, 1.14:1, 1.16:1, 1.18:1 or 1.20:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0017] In some alternative embodiments, the concentration of the hydrochloric acid is 1-2M, for example, it can be 1.0M, 1.1M, 1.2M, 1.3M, 1.4M, 1.5M, 1.6M, 1.7M, 1.8M, 1.9M or 2.0M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0018] In some alternative embodiments, the sodium behenate solution is adjusted to pH 7-8, for example, to 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8.0, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0019] In some alternative embodiments, the concentration of the mixed metal solution is 0.5-1.5M, for example, it can be 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, 1.0M, 1.1M, 1.2M, 1.3M, 1.4M or 1.5M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the molar ratio of ferric chloride to copper chloride in the mixed metal solution is (8-15):1, for example, it can be 8.0:1, 8.7:1, 9.4:1, 10.1:1, 10.8:1, 11.5:1, 12.2:1, 12.9:1, 13.6:1, 14.3:1 or 15.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the ratio of the total molar amounts of behenic acid to ferric chloride to copper chloride is (2.8-3.2):1, for example, it can be 2.80:1, 2.84:1, 2.88:1, 2.92:1, 2.96:1, 3.00:1, 3.04:1, 3.08:1, 3.12:1, 3.16:1 or 3.20:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the reaction temperature after adding the mixed metal solution A and stirring is 60-80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the reaction time after adding the mixed metal solution A is 2-4 hours, for example, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, or 4.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the concentration of the polyvinyl alcohol aqueous solution is 5-10 wt%, for example, it may be 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.% or 10.0 wt.%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the mass ratio of the iron / copper berghehenryi complex to the polyvinyl alcohol aqueous solution is 1:(3-6), for example, it can be 1:3.0, 1:3.3, 1:3.6, 1:3.9, 1:4.2, 1:4.5, 1:4.8, 1:5.1, 1:5.4, 1:5.7 or 1:6.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the grinding and dispersion time is 4-10 hours, for example, 4.0 hours, 4.6 hours, 5.2 hours, 5.8 hours, 6.4 hours, 7.0 hours, 7.6 hours, 8.2 hours, 8.8 hours, 9.4 hours, or 10.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the solid content of the aqueous metal source dispersion is 15-25%, for example, it can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] As a preferred embodiment of the present invention, in step S2, the volume ratio of tetrahydrofuran to N,N-dimethylformamide in the mixed solvent is (3-5):1, for example, it can be 3.0:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4.0:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5.0:1, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In some alternative embodiments, the molar ratio of gallic acid to octadecylamine is 1:(1-1.2), for example, it can be 1:1.00, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.10, 1:1.12, 1:1.14, 1:1.16, 1:1.18 or 1:1.20, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the mass-to-volume ratio of the total mass of gallic acid and octadecylamine to the mixed solvent is 1 g:(4-8) mL, for example, it can be 1 g:4.0 mL, 1 g:4.4 mL, 1 g:4.8 mL, 1 g:5.2 mL, 1 g:5.6 mL, 1 g:6.0 mL, 1 g:6.4 mL, 1 g:6.8 mL, 1 g:7.2 mL, 1 g:7.6 mL or 1 g:8.0 mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] In some alternative embodiments, the molar ratio of the catalyst to gallic acid is (1-1.2):1, for example, it can be 1.00:1, 1.02:1, 1.04:1, 1.06:1, 1.08:1, 1.10:1, 1.12:1, 1.14:1, 1.16:1, 1.18:1 or 1.20:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the reaction temperature of the reaction solution B is 25-40°C, for example, it can be 25.0°C, 26.5°C, 28.0°C, 29.5°C, 31.0°C, 32.5°C, 34.0°C, 35.5°C, 37.0°C, 38.5°C or 40.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the reaction time of the reaction solution B is 12-24 hours, for example, 12.0 hours, 13.2 hours, 14.4 hours, 15.6 hours, 16.8 hours, 18.0 hours, 19.2 hours, 20.4 hours, 21.6 hours, 22.8 hours, or 24.0 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the mass ratio of the modified ligand to ethanol is 1:(0.5-1.5), for example, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0035] In some alternative embodiments, the mass ratio of the modified ligand to the styrene-acrylic acid copolymer emulsion is 1:(2-4), for example, it can be 1:2.0, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3.0, 1:3.2, 1:3.4, 1:3.6, 1:3.8 or 1:4.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the solid content of the pre-grinding liquid is 25-35%, for example, it can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34% or 35%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the wet grinding time of the pre-grinding liquid is 6-12 hours, for example, 6.0 hours, 6.6 hours, 7.2 hours, 7.8 hours, 8.4 hours, 9.0 hours, 9.6 hours, 10.2 hours, 10.8 hours, 11.4 hours or 12.0 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the solid content of the aqueous high-steric ligand dispersion is 20-30%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0039] As a preferred technical solution of the present invention, in step S3, the temperature of nitrogen purging to remove water is 140-160℃, for example, it can be 140℃, 142℃, 144℃, 146℃, 148℃, 150℃, 152℃, 154℃, 156℃, 158℃ or 160℃, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the nitrogen purging time for water removal is 1-2 hours, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the molar ratio of yttrium chloride, ytterbium chloride and erbium chloride in the rare earth chloride is 78:20:2.

[0042] In some alternative embodiments, the volume ratio of oleic acid to 1-octadecene in the second mixed solvent is 1:(1-2), for example, it can be 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the concentration of ammonium fluoride in the methanol solution is 0.2-0.6M, for example, it can be 0.20M, 0.24M, 0.28M, 0.32M, 0.36M, 0.40M, 0.44M, 0.48M, 0.52M, 0.56M or 0.60M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the concentration of sodium hydroxide in the methanol solution is 0.1-0.4M, for example, it can be 0.10M, 0.13M, 0.16M, 0.19M, 0.22M, 0.25M, 0.28M, 0.31M, 0.34M, 0.37M or 0.40M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the molar ratio of the rare earth chloride to ammonium fluoride and sodium hydroxide is 1:(3.5-5):(2-3), for example, it can be 1:(3.50, 3.65, 3.80, 3.95, 4.10, 4.25, 4.40, 4.55, 4.70, 4.85 or 5.00):(2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0), but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the reaction temperature of the reaction solution C is 280-310°C, for example, it can be 280°C, 283°C, 286°C, 289°C, 292°C, 295°C, 298°C, 301°C, 304°C, 307°C or 310°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] In some optional embodiments, the reaction time of the reaction solution C is 1-2 hours, for example, it can be 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0048] In some optional embodiments, the mass ratio of the oil-soluble upconversion luminescent nanoparticles to DSPE-PEG2000 is 1:(0.5-1), for example, it can be 1:0.50, 1:0.55, 1:0.60, 1:0.65, 1:0.70, 1:0.75, 1:0.80, 1:0.85, 1:0.90, 1:0.95 or 1:1.00, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In some alternative embodiments, the temperature of the ultrasonic hydration is 60-70°C, for example, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the ultrasonic hydration time is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] In some optional embodiments, the concentration of the aqueous upconversion luminescent nanoparticle dispersion is 1-5 mg / mL, for example, it can be 1.0 mg / mL, 1.4 mg / mL, 1.8 mg / mL, 2.2 mg / mL, 2.6 mg / mL, 3.0 mg / mL, 3.4 mg / mL, 3.8 mg / mL, 4.2 mg / mL, 4.6 mg / mL or 5.0 mg / mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0052] In some optional embodiments, the concentration of the sodium polyacrylate solution is 0.5-2 wt.%, for example, it may be 0.50 wt.%, 0.65 wt.%, 0.80 wt.%, 0.95 wt.%, 1.10 wt.%, 1.25 wt.%, 1.40 wt.%, 1.55 wt.%, 1.70 wt.%, 1.85 wt.%, or 2.00 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0053] In some optional embodiments, the mass ratio of the lanthanum hexaboride nanoparticles to sodium polyacrylate is (5-10):1, for example, it can be 5.0:1, 5.5:1, 6.0:1, 6.5:1, 7.0:1, 7.5:1, 8.0:1, 8.5:1, 9.0:1, 9.5:1 or 10.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0054] In some optional embodiments, the ultrasonic fragmentation time is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0055] In some optional embodiments, the concentration of the photothermal conversion dispersion is 0.5-2 mg / mL, for example, it can be 0.50 mg / mL, 0.65 mg / mL, 0.80 mg / mL, 0.95 mg / mL, 1.10 mg / mL, 1.25 mg / mL, 1.40 mg / mL, 1.55 mg / mL, 1.70 mg / mL, 1.85 mg / mL or 2.00 mg / mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0056] As a preferred technical solution of the present invention, in step S4, the solid content of the barrier primer is 10-20%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] In some optional embodiments, the mass ratio of the functional back coating liquid mesoporous silica, PEDOT:PSS aqueous dispersion, and aqueous polyurethane resin is (5-10):(1-3):100, for example, it can be (5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5 or 10.0):(1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 or 3.0):100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0058] In some optional embodiments, the solid mass ratio of the aqueous metal source dispersion to the aqueous high steric hindrance ligand dispersion is (1-2):1, for example, it can be 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0059] The leveling agents are BYK-333 and TEGO Glide 450.

[0060] In some optional embodiments, the amount of leveling agent added is 0.1-0.5% of the total mass of the color developing layer coating liquid, for example, it can be 0.10%, 0.14%, 0.18%, 0.22%, 0.26%, 0.30%, 0.34%, 0.38%, 0.42%, 0.46% or 0.50%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0061] In some optional embodiments, the mixing temperature is 10-20°C, for example, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C or 20°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0062] In some optional embodiments, the mass fraction of lanthanum hexaboride nanoparticles in the color development coating solution is 0.02-0.08% of the total solids, for example, it can be 0.020%, 0.026%, 0.032%, 0.038%, 0.044%, 0.050%, 0.056%, 0.062%, 0.068%, 0.074%, or 0.080%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0063] In some optional embodiments, the particle size of the PMMA crosslinked microspheres is 1-3 μm, for example, it can be 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm or 3.0 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0064] In some optional embodiments, the mass ratio of the PMMA crosslinked microspheres to the aqueous UV-curable polyurethane acrylate emulsion is (3-8):100, for example, it can be 3.0:100, 3.5:100, 4.0:100, 4.5:100, 5.0:100, 5.5:100, 6.0:100, 6.5:100, 7.0:100, 7.5:100 or 8.0:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0065] In some optional embodiments, the amount of Irgacure 2959 photoinitiator is 1-4% of the mass of the aqueous UV-curable polyurethane acrylate emulsion, for example, it can be 1.0%, 1.3%, 1.6%, 1.9%, 2.2%, 2.5%, 2.8%, 3.1%, 3.4%, 3.7% or 4.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0066] In some optional embodiments, the solid content of the top protective liquid is 20-30%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0067] As a preferred technical solution of the present invention, in step S5, the drying temperature of the barrier primer is 80-100℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃ or 100℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0068] In some alternative embodiments, the thickness of the first dry film is 0.5-1.5 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0069] In some optional embodiments, the drying temperature of the functional back coating liquid is 80-100°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0070] In some alternative embodiments, the thickness of the second dry film is 1-3 μm, for example, it can be 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm or 3.0 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0071] In some optional embodiments, the thickness of the third dry film is 0.3-1.0 μm, for example, it can be 0.30 μm, 0.37 μm, 0.44 μm, 0.51 μm, 0.58 μm, 0.65 μm, 0.72 μm, 0.79 μm, 0.86 μm, 0.93 μm or 1.00 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0072] In some alternative embodiments, the pre-drying temperature is 30-40°C, for example, it can be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0073] In some optional embodiments, the final drying temperature is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0074] In some optional embodiments, the thickness of the fourth dry film is 10-15 μm, for example, it can be 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm, 12.0 μm, 12.5 μm, 13.0 μm, 13.5 μm, 14.0 μm, 14.5 μm or 15.0 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0075] In some optional embodiments, the drying temperature of the top protective liquid is 60-80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0076] In some optional embodiments, the drying time of the top protective liquid is 1-2 min, for example, it can be 1.0 min, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min or 2.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0077] In some optional embodiments, the UV curing energy is 300-600 mJ / cm². 2 For example, it could be 300mJ / cm 2 330mJ / cm 2 360mJ / cm 2 390mJ / cm 2 420mJ / cm 2 450mJ / cm 2 480mJ / cm 2 510mJ / cm 2 540mJ / cm 2 570mJ / cm 2 Or 600mJ / cm 2 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0078] In some optional embodiments, the thickness of the fifth dry film is 2-4 μm, for example, it can be 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm or 4.0 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0079] Secondly, the present invention provides a multifunctional medical dry thermal film, which is prepared according to the preparation method described in the first aspect. Its structure includes a blue PET substrate and a plurality of dry film structures disposed on the back and front sides of the blue PET substrate, wherein:

[0080] The back of the blue PET substrate is sequentially provided with a first dry film formed by a barrier primer and a second dry film formed by a functional back coating liquid;

[0081] The blue PET substrate has a third dry film formed by an aqueous upconversion luminescent nanoparticle dispersion in a preset area on the front edge, and a fourth dry film formed by a color development layer coating liquid and a fifth dry film formed by a top protective liquid in the entire front area.

[0082] The preset area is preferably a local area located on the front side of the blue PET substrate near the outer peripheral edge. It can be set continuously or intermittently along one side edge, adjacent two side edges, or peripheral edge. It is mainly used to carry upconversion luminescent nanoparticles to form anti-counterfeiting marks, rather than as the main imaging area.

[0083] This application employs a solid-phase coordination mechanism of iron / copper berghedate with a highly sterically hindered polyphenol ligand in the colorimetric system. The prepared iron / copper berghedate complex is essentially a metal soap with long-chain alkyl groups, which retains the Fe... 3+ / Cu 2+ The coordination relationship with carboxylate groups, through long-chain alkyl groups, endows the material with a defined melting temperature range and low room-temperature migration. After the particles are stably dispersed in an aqueous phase by PVA, this type of metal soap can form a relatively uniform solid metal source distribution in the coating. When the thermistor is locally heated, the particles first undergo softening or partial melting, allowing the metal centers to migrate to surrounding ligand-rich areas, while the unheated areas remain predominantly solid, reducing the likelihood of background color development across the entire film. Compared to directly using readily soluble metal salts, this application establishes a buffer between "solid-phase storage and localized melting release" through metal soaps, which is beneficial for achieving a balance between spatial resolution and color development controllability.

[0084] This application yields a modified ligand that retains the ortho-phenolic hydroxyl group and other properties that can interact with Fe. 3+ / Cu 2+The functional groups involved in coordination chelation, along with the introduction of amide bonds and long chains, make the molecule more prone to exist in a conformation stable by intramolecular hydrogen bonds at room temperature, exhibiting an overall hydrophobic solid behavior. After the ligands are dispersed in the styrene-acrylic acid copolymer emulsion via wet milling, they are fixed in the polymer matrix in particulate form, reducing their free diffusion during the coating stage and the probability of premature contact with the metal source. During thermal printing, localized heating can soften the ligand particles, disrupting some intramolecular hydrogen bonds and making coordination sites more easily exposed in the interfacial region. This allows for preferential interaction with Fe from the metal soap in the heated region. 3+ / Cu 2+ Coordination occurs to form dark complexes. By combining sterically hindered solid ligands and metal soaps, this application attempts to lock the colorimetric reaction at the solid-phase interface near the heated pixel, weakening the spontaneous coordination tendency at room temperature, and making the grayscale response more dependent on thermal history rather than storage time.

[0085] This application introduces the photothermal conversion effect of lanthanum hexaboride nanoparticles to reduce the dependence of the developing layer on the energy of the thermal head. Lanthanum hexaboride nanoparticles, dispersed in sodium polyacrylate, are added to the developing layer coating solution to provide a certain degree of near-infrared absorption while maintaining optical transmittance. During printing, in addition to direct contact heat transfer, the thermal head generates radiation and localized temperature rise. The lanthanum hexaboride nanoparticles can absorb some of the radiative components and convert them into heat energy, preferentially forming microscopic temperature peaks near the particles. This allows the color development reaction to occur more concentrated at the existing metal source / ligand particle interface at the microscale, rather than extending excessively to areas far from the heating center. The introduction of this low-dose photothermal filler helps improve imaging sensitivity and edge sharpness without significantly increasing the overall heat load, while controlling the dosage limits the impact on background haze and tone within an adjustable range.

[0086] This application constructs a back-side structure of "barrier primer + functional back coating," combined with a color development layer and a top protective coating, to achieve layered regulation of the microenvironment of the imaging layer. The barrier primer, formed by a highly cross-linked acrylic resin emulsion, provides a relatively dense polymer network on the back of the PET film, which helps reduce the permeation rate of environmental moisture and polar small molecules from the back to the film, thereby mitigating the impact of changes in humidity and heat conditions on the metal soaps and polyphenol ligands in the color development layer. The functional back coating introduces mesoporous silica and PEDOT:PSS. The mesoporous silica adjusts the surface roughness and local adsorption capacity of the back side through particle morphology and pore structure, which helps reduce the complete contact area during wafer stacking and buffers environmental humidity fluctuations. The conductive network constructed by PEDOT:PSS provides a dissipation path for static charge, reducing the risk of carding or dust adsorption caused by static electricity accumulation during wafer transport. Above the front color development layer, a cross-linked protective layer formed by water-based UV-cured polyurethane acrylate provides mechanical and chemical protection for the color development system. The cross-linked PMMA microspheres form a controllable micro-roughness structure on the surface, giving the surface a certain matte and damping property, which is convenient for writing and reading. At the same time, by controlling the microsphere content and particle size, the influence of the top layer on transmittance and haze is kept within a suitable range for medical image reading.

[0087] This application employs a localized upconversion luminescent nanoparticle layer design for anti-counterfeiting functionality. Oil-soluble upconversion luminescent nanoparticles are prepared in an oleic acid / 1-octadecene system and transferred to an aqueous phase using DSPE-PEG2000, resulting in an upconversion luminescent nanoparticle dispersion with relatively good dispersion stability in an aqueous system. During actual film formation, a thin layer of the upconversion luminescent layer is applied only to a predetermined area on the front edge of the PET substrate, allowing this area to generate visible light signals under specific near-infrared wavelength excitation, while the main imaging area does not directly contain these particles. This arrangement facilitates spatial decoupling of anti-counterfeiting functionality from imaging performance: on the one hand, it provides easily identifiable feature markers when needed; on the other hand, it reduces the interference of anti-counterfeiting particles on the optical transmission and color development stability of the imaging layer, providing a feasible path to balance anti-counterfeiting and imaging performance within the same film.

[0088] There is a certain synergistic relationship between the various processes and structural designs in this application in terms of color development control and stability. In the early stages, a combination of metal soap and high-steric-barrier solid ligands was used to fix the metal source and color development coordination sites separately within solid particles. Factors such as particle size and glass transition temperature were used to limit the interaction at room temperature, ensuring that color development is mainly concentrated in the thermal field region. The addition of photothermal fillers enhanced the thermal driving force locally, allowing for a sufficient coordination reaction rate even under a relatively mild macroscopic process window. Backside barrier and functional back coating reduced the migration of moisture and impurities caused by environmental factors. The top protective layer further provided physical and optical shielding for the color development layer, while the upconversion anti-counterfeiting layer supplemented the identification function without significantly altering the overall structure. Through the combination of solid-phase coordination, localized photothermal enhancement, multi-layer environmental control, and edge anti-counterfeiting design, a technical route different from traditional silver halide films and conventional colorless dye thermosensitive materials was formed in the silver-free thermosensitive system in terms of color development mechanism, structural hierarchy, and functional integration. This provides an optional solution for achieving a comprehensive balance between imaging performance and usability performance in medical dry thermosensitive films.

[0089] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0090] By preparing solid dispersions of the iron / copper berghedate complex and the highly sterically hindered polyphenol ligand, Fe was triggered in the heating region of the thermistor. 3+ / Cu 2+ Coordination with polyphenols for color development, compared to systems that rely on silver salts or traditional colorless dye acids for color development, is more conducive to reducing the haze and smudging caused by spontaneous color development at room temperature and thermal diffusion. This allows the grayscale to be mainly controlled by thermal history, providing a route to obtain more controllable density and gradation in a silver-free system.

[0091] The low-dose introduction of lanthanum hexaboride nanoparticles into the color development layer for near-infrared photothermal conversion helps to improve the temperature rise efficiency at the local microscale without significantly sacrificing visible light transmittance. This enables a more sensitive color development response and relatively clear edge contours even with a relatively mild overall energy input, providing room for adjustment between printing energy consumption and image quality.

[0092] The back side uses a combination of a highly cross-linked acrylic barrier layer and a mesoporous silica / PEDOT:PSS functional back coating, which helps to reduce the impact of environmental humidity and static electricity accumulation on the developing layer and the film transport process. The front side uses UV-cured polyurethane acrylate combined with PMMA cross-linked microspheres to form a matte protective layer, which controls the haze while taking into account mechanical protection, writability and reading comfort, making the film operation experience easier to adjust and consistent in clinical use scenarios.

[0093] A thin layer of water-based upconversion luminescent nanoparticles is introduced at the edge of the substrate front, enabling the film to have identifiable luminescent markings under specific near-infrared light irradiation, while the main imaging area maintains its original structure and optical properties. This layout is conducive to achieving anti-counterfeiting and traceability functions without complicating the imaging system, and facilitates product management and quality identification. Attached Figure Description

[0094] Figure 1 This is a schematic diagram of the structure of the multifunctional medical dry thermal film obtained in Embodiment 1 of this application.

[0095] In the diagram: 1. Blue PET substrate; 2. First dry film; 3. Second dry film; 4. Third dry film; 5. Fourth dry film; 6. Fifth dry film. Detailed Implementation

[0096] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include any obvious substitutions and modifications made to the embodiments described herein.

[0097] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0098] Example 1

[0099] This embodiment provides a multifunctional medical dry thermal film and its preparation method. The preparation method of the multifunctional medical dry thermal film specifically includes the following steps:

[0100] S1: Behenic acid is added to deionized water at 85°C, with a mass ratio of behenic acid to deionized water of 1:8. A 2.5M sodium hydroxide solution is added dropwise, and the reaction is allowed to proceed for 1.8 hours to obtain a sodium behenate solution, with a molar ratio of sodium hydroxide to behenic acid of 1.15:1. The pH is adjusted to 7.8 with 1.8M hydrochloric acid to obtain reaction solution A. A 1.2M mixed metal solution is then added dropwise, wherein the molar ratio of ferric chloride to copper chloride in the mixed metal solution is... The ratio of behenic acid to ferric chloride to copper chloride was 12:1, and the total molar ratio of behenic acid to ferric chloride to copper chloride was 3.1:1. The mixture was stirred at 75°C for 3.5 h, filtered, washed, and dried to obtain an iron / copper behenic acid complex. The iron / copper behenic acid complex was mixed with an 8 wt% polyvinyl alcohol aqueous solution at a mass ratio of 1:5 to obtain a dispersion. The dispersion was then ground and dispersed in a sand mill for 8 h, with deionized water added during the grinding process to obtain an aqueous metal source dispersion with a solid content of 22%.

[0101] S2: Gallic acid and octadecylamine were added to a mixed solvent, wherein the volume ratio of tetrahydrofuran to N,N-dimethylformamide in the mixed solvent was 4:1, the molar ratio of gallic acid to octadecylamine was 1:1.15, and the mass-volume ratio of the total mass of gallic acid and octadecylamine to the mixed solvent was 1 g:7 mL. Dicyclohexylcarbodiimide catalyst was added to obtain reaction solution B, wherein the molar ratio of catalyst to gallic acid was 1.1:1. The reaction was stirred at 35°C for 20 h, and the modified ligand was obtained by hot filtration, rotary evaporation, and recrystallization. The modified ligand was mixed with ethanol at a mass ratio of 1:1.2, and then styrene-acrylic acid copolymer emulsion was added, wherein the mass ratio of the modified ligand to styrene-acrylic acid copolymer emulsion was 1:3.5. Deionized water was added to adjust the solid content to 32% to obtain a pre-grinding solution, which was placed in a bead mill for wet grinding for 10 h to obtain an aqueous high-steric ligand dispersion with a solid content of 28%.

[0102] S3: Rare earth chlorides were added to the second mixed solvent, and the mixture was purged with nitrogen at 155°C for 1.8 h to remove water. The rare earth chlorides were obtained by mixing yttrium chloride, ytterbium chloride, and erbium chloride in a molar ratio of 78:20:2. The volume ratio of oleic acid to 1-octadecene in the second mixed solvent was 1:1.8. Methanol solution was added under a nitrogen atmosphere to obtain reaction solution C, in which the concentration of ammonium fluoride in the methanol solution was 0.5 M, the concentration of sodium hydroxide was 0.3 M, and the molar ratio of rare earth chlorides to ammonium fluoride and sodium hydroxide was 1:4.5:2.8. The mixture was heated to 300°C and reacted for 1.5 h. After cooling, centrifugation, and washing, oil-soluble upconversion luminescent nanoparticles were obtained. Luminescent nanoparticles were dispersed in chloroform using DSPE-PEG2000 at a mass ratio of 1:0.8. The chloroform was removed by rotary evaporation to form a thin film. Deionized water was added and the film was ultrasonically hydrated in a 65°C water bath for 50 min to obtain an aqueous upconversion luminescent nanoparticle dispersion with a concentration of 4 mg / mL. Lanthanum hexaboride nanoparticles were added to a 1.5 wt.% sodium polyacrylate solution at a mass ratio of 8:1. The solution was ultrasonically broken up in an ice-water bath for 50 min to obtain a photothermal conversion dispersion with a concentration of 1.8 mg / mL.

[0103] S4: Prepare a highly cross-linked acrylic resin emulsion with a solid content of 18% as a barrier primer; mix mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion, and waterborne polyurethane resin at a mass ratio of 8:2.5:100, and degas using ultrasound to obtain a functional back coating; mix an aqueous metal source dispersion and an aqueous high-steric barrier ligand dispersion at a solid mass ratio of 1.8:1, add a photothermal conversion dispersion and leveling agent BYK-333, wherein the amount of leveling agent added is 0.4% of the total mass of the color-developing layer coating liquid, and stir and mix evenly at 18°C ​​to obtain a color-developing layer coating liquid, wherein the mass fraction of lanthanum hexaboride nanoparticles is 0.07% of the total solids of the color-developing layer coating liquid; mix an aqueous UV-curable polyurethane acrylate emulsion with PMMA cross-linked microspheres with a particle size of 2.5μm, wherein the mass ratio of PMMA cross-linked microspheres to aqueous UV-curable polyurethane acrylate emulsion is 7:100, and add Irgacure Irgacure 2959 photoinitiator is used, with the amount of Irgacure 2959 photoinitiator being 3% of the mass of the waterborne UV-curable polyurethane acrylate emulsion. The solid content is adjusted to 28% to obtain the top protective liquid.

[0104] S5: A barrier primer is coated on the back of a blue PET substrate 1 and dried at 95°C to obtain a first dry film 2 with a thickness of 1.2 μm. A functional back coating is then coated on top and dried at 90°C to obtain a second dry film 3 with a thickness of 2.5 μm. An aqueous upconversion luminescent nanoparticle dispersion is coated on a predetermined area at the edge of the front side of the substrate and dried to obtain a third dry film 4 with a thickness of 0.8 μm. Subsequently, a color-developing layer coating is coated on the entire front side of the substrate, pre-dried at 38°C, and finally dried at 58°C to obtain a fourth dry film 5 with a thickness of 14 μm. Finally, a top protective liquid is coated on top of the color-developing layer, dried at 75°C for 1.8 min, and then cured in a UV lamp chamber with a curing energy of 500 mJ / cm². 2 A fifth dry film 6 with a thickness of 3.5 μm was obtained, and the film was wound up to obtain a multifunctional medical dry thermal film. Figure 1 This is a schematic diagram of a multifunctional medical dry thermal film, as shown below. Figure 1 As shown, the back of the blue PET substrate 1 is provided with a first dry film 2 and a second dry film 3 in sequence, the front edge area of ​​the blue PET substrate 1 is provided with a third dry film 4, and the entire front of the blue PET substrate 1 is provided with a fourth dry film 5 and a fifth dry film 6 in sequence.

[0105] Example 2

[0106] This embodiment provides a multifunctional medical dry thermal film and its preparation method. The preparation method of the multifunctional medical dry thermal film specifically includes the following steps:

[0107] S1: Behenic acid was added to deionized water at 75°C, with a mass ratio of behenic acid to deionized water of 1:5. A 1M sodium hydroxide solution was added dropwise and reacted for 1 hour to obtain a sodium behenate solution, with a molar ratio of sodium hydroxide to behenic acid of 1:1. The pH was adjusted to 7 with 1M hydrochloric acid to obtain reaction solution A. A 0.5M mixed metal solution was added dropwise, with a molar ratio of ferric chloride to copper chloride of 8:1 and a total molar ratio of behenic acid to ferric chloride to copper chloride of 2.8:1. The mixture was stirred at 60°C for 2 hours, filtered, washed, and dried to obtain an iron / copper behenate complex. The iron / copper behenate complex was mixed with a 10wt% polyvinyl alcohol aqueous solution at a mass ratio of 1:3 to obtain a dispersion. The dispersion was ground and dispersed in a sand mill for 4 hours, with deionized water added during the grinding process to obtain an aqueous metal source dispersion with a solid content of 15%.

[0108] S2: Gallic acid and octadecylamine are added to a mixed solvent, wherein the volume ratio of tetrahydrofuran to N,N-dimethylformamide in the mixed solvent is 3:1, the molar ratio of gallic acid to octadecylamine is 1:1, and the mass-volume ratio of the total mass of gallic acid and octadecylamine to the mixed solvent is 1 g: 4 mL. Dicyclohexylcarbodiimide catalyst is added to obtain reaction solution B, wherein the molar ratio of catalyst to gallic acid is 1:1. The reaction is stirred at 25°C for 12 h, and the modified ligand is obtained by hot filtration, rotary evaporation, and recrystallization. The modified ligand is mixed with ethanol at a mass ratio of 1:0.5, and then styrene-acrylic acid copolymer emulsion is added, wherein the mass ratio of modified ligand to styrene-acrylic acid copolymer emulsion is 1:2. Deionized water is added to adjust the solid content to 25% to obtain a pre-grinding solution, which is placed in a bead mill for wet grinding for 6 h to obtain an aqueous high-steric ligand dispersion with a solid content of 20%.

[0109] S3: Rare earth chlorides were added to the second mixed solvent, and the mixture was purged with nitrogen at 140°C for 1 hour to remove water. The rare earth chlorides were obtained by mixing yttrium chloride, ytterbium chloride, and erbium chloride in a molar ratio of 78:20:2. The volume ratio of oleic acid to 1-octadecene in the second mixed solvent was 1:1. Methanol solution was added under a nitrogen atmosphere to obtain reaction solution C, in which the concentration of ammonium fluoride in the methanol solution was 0.2M, the concentration of sodium hydroxide was 0.1M, and the molar ratio of rare earth chlorides to ammonium fluoride and sodium hydroxide was 1:3.5:2. The mixture was heated to 280°C and reacted for 1 hour. After cooling, centrifugation, and washing, oil-soluble upconversion luminescent nanoparticles were obtained. Oil-soluble upconversion luminescent nanoparticles were dispersed in chloroform using DSPE-PEG2000 at a mass ratio of 1:0.5. The chloroform was removed by rotary evaporation to form a thin film. Deionized water was added and the film was ultrasonically hydrated in a 70°C water bath for 30 min to obtain an aqueous upconversion luminescent nanoparticle dispersion with a concentration of 1 mg / mL. Lanthanum hexaboride nanoparticles were added to a 0.5 wt.% sodium polyacrylate solution, with a mass ratio of 5:1. The solution was ultrasonically broken up in an ice-water bath for 30 min to obtain a photothermal conversion dispersion with a concentration of 0.5 mg / mL.

[0110] S4: Prepare a highly cross-linked acrylic resin emulsion with a solid content of 10% as a barrier primer; mix mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion, and waterborne polyurethane resin at a mass ratio of 5:1:100, and degas using ultrasonication to obtain a functional back coating; mix an aqueous metal source dispersion and an aqueous high-steric barrier ligand dispersion at a solid mass ratio of 1:1, add a photothermal conversion dispersion and leveling agent BYK-333, wherein the amount of leveling agent added is 0.1% of the total mass of the color-developing layer coating liquid, and stir and mix evenly at 10°C to obtain a color-developing layer coating liquid, wherein the mass fraction of lanthanum hexaboride nanoparticles is 0.02% of the total solid content of the color-developing layer coating liquid; mix an aqueous UV-curable polyurethane acrylate emulsion with PMMA cross-linked microspheres with a particle size of 1μm, wherein the mass ratio of PMMA cross-linked microspheres to aqueous UV-curable polyurethane acrylate emulsion is 3:100, and add Irgacure Irgacure 2959 photoinitiator is used, with the amount of Irgacure 2959 photoinitiator being 1% of the mass of the waterborne UV-curable polyurethane acrylate emulsion. The solid content is adjusted to 20% to obtain the top protective liquid.

[0111] S5: A barrier primer is coated on the back of the blue PET substrate 1 and dried at 80℃, resulting in a first dry film 2 with a thickness of 0.5μm. A functional back coating is then coated on top and dried at 80℃, resulting in a second dry film 3 with a thickness of 1μm. An aqueous upconversion luminescent nanoparticle dispersion is coated on a predetermined area at the edge of the substrate's front side and dried, resulting in a third dry film 4 with a thickness of 0.3μm. Subsequently, a color-developing layer coating is applied to the entire front side of the substrate, pre-dried at 30℃, and finally dried at 50℃, resulting in a fourth dry film 5 with a thickness of 10μm. Finally, a top protective liquid is coated on top of the color-developing layer, dried at 60℃ for 1 min, and then cured using a UV lamp at a curing energy of 300mJ / cm². 2 The fifth dry film, 6, is 2μm thick, and is then wound up to obtain a multifunctional medical dry thermal film.

[0112] Example 3

[0113] This embodiment provides a multifunctional medical dry thermal film and its preparation method. The preparation method of the multifunctional medical dry thermal film specifically includes the following steps:

[0114] S1: Behenic acid is added to deionized water at 80℃, with a mass ratio of behenic acid to deionized water of 1:7. A 1.5M sodium hydroxide solution is added dropwise, and the reaction is allowed to proceed for 1.2 hours to obtain a sodium behenate solution, with a molar ratio of sodium hydroxide to behenic acid of 1.05:1. The pH is adjusted to 7.2 with 1.2M hydrochloric acid to obtain reaction solution A. A 0.8M mixed metal solution is then added dropwise, wherein the molar ratio of ferric chloride to copper chloride in the mixed metal solution is... The ratio of behenic acid to ferric chloride to copper chloride was 10:1, and the total molar ratio of behenic acid to ferric chloride to copper chloride was 2.9:1. The mixture was stirred at 65°C for 2.5 h, filtered, washed, and dried to obtain an iron / copper behenic acid complex. The iron / copper behenic acid complex was mixed with a 5 wt% polyvinyl alcohol aqueous solution at a mass ratio of 1:4 to obtain a dispersion. The dispersion was then ground and dispersed in a sand mill for 6 h, with deionized water added during the grinding process to obtain an aqueous metal source dispersion with a solid content of 18%.

[0115] S2: Gallic acid and octadecylamine were added to a mixed solvent, wherein the volume ratio of tetrahydrofuran to N,N-dimethylformamide in the mixed solvent was 4.5:1, the molar ratio of gallic acid to octadecylamine was 1:1.05, and the mass-volume ratio of the total mass of gallic acid and octadecylamine to the mixed solvent was 1 g:5 mL. Dicyclohexylcarbodiimide catalyst was added to obtain reaction solution B, wherein the molar ratio of catalyst to gallic acid was 1.15:1. The reaction was stirred at 30°C for 16 h, and the modified ligand was obtained by hot filtration, rotary evaporation, and recrystallization. The modified ligand was mixed with ethanol at a mass ratio of 1:0.8, and then styrene-acrylic acid copolymer emulsion was added, wherein the mass ratio of the modified ligand to styrene-acrylic acid copolymer emulsion was 1:2.5. Deionized water was added to adjust the solid content to 28% to obtain a pre-grinding solution, which was placed in a bead mill for wet grinding for 8 h to obtain an aqueous high-steric ligand dispersion with a solid content of 22%.

[0116] S3: Rare earth chlorides were added to the second mixed solvent, and the mixture was purged with nitrogen at 145°C for 1.2 h to remove water. The rare earth chlorides were obtained by mixing yttrium chloride, ytterbium chloride, and erbium chloride in a molar ratio of 78:20:2. The volume ratio of oleic acid to 1-octadecene in the second mixed solvent was 1:1.2. Methanol solution was added under a nitrogen atmosphere to obtain reaction solution C, in which the concentration of ammonium fluoride in the methanol solution was 0.4 M, the concentration of sodium hydroxide was 0.2 M, and the molar ratio of rare earth chlorides to ammonium fluoride and sodium hydroxide was 1:4.0:2.2. The mixture was heated to 290°C and reacted for 1.2 h. After cooling, centrifugation, and washing, oil-soluble upconversion luminescent nanoparticles were obtained. Luminescent nanoparticles were dispersed in chloroform using DSPE-PEG2000 at a mass ratio of 1:0.6. The chloroform was removed by rotary evaporation to form a thin film. Deionized water was added and the film was ultrasonically hydrated in a 62°C water bath for 40 min to obtain an aqueous upconversion luminescent nanoparticle dispersion with a concentration of 2 mg / mL. Lanthanum hexaboride nanoparticles were added to a 1.0 wt.% sodium polyacrylate solution at a mass ratio of 7:1. The solution was ultrasonically broken down in an ice-water bath for 40 min to obtain a photothermal conversion dispersion with a concentration of 1.0 mg / mL.

[0117] S4: Prepare a highly cross-linked acrylic resin emulsion with a solid content of 12% as a barrier primer; mix mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion, and waterborne polyurethane resin at a mass ratio of 7:1.5:100, and degas using ultrasonication to obtain a functional back coating; mix an aqueous metal source dispersion and an aqueous high-steric ligand dispersion at a solid mass ratio of 1.2:1, add a photothermal conversion dispersion and a leveling agent TEGO Glide 450, wherein the amount of the leveling agent added is 0.2% of the total mass of the color-developing layer coating liquid, and stir and mix evenly at 12°C to obtain a color-developing layer coating liquid, wherein the mass fraction of lanthanum hexaboride nanoparticles is 0.04% of the total solid content of the color-developing layer coating liquid; mix an aqueous UV-curable polyurethane acrylate emulsion with PMMA cross-linked microspheres with a particle size of 1.5μm, wherein the mass ratio of PMMA cross-linked microspheres to aqueous UV-curable polyurethane acrylate emulsion is 5:100, and add Irgacure 2959 photoinitiator, wherein the amount of Irgacure 2959 photoinitiator added is 2% of the mass of the waterborne UV-curable polyurethane acrylate emulsion, and the solid content is adjusted to 22% to obtain the top protective liquid.

[0118] S5: A barrier primer is coated on the back of the blue PET substrate 1 and dried at 85°C, resulting in a first dry film 2 with a thickness of 0.8 μm. A functional back coating is then coated on top and dried at 85°C, resulting in a second dry film 3 with a thickness of 1.5 μm. An aqueous upconversion luminescent nanoparticle dispersion is coated on a predetermined area at the edge of the substrate's front side and dried, resulting in a third dry film 4 with a thickness of 0.5 μm. Subsequently, a color-developing layer coating is applied to the entire front side of the substrate, pre-dried at 32°C, and finally dried at 52°C, resulting in a fourth dry film 5 with a thickness of 11 μm. Finally, a top protective liquid is coated on top of the color-developing layer, dried at 65°C for 1.2 min, and then cured using a UV lamp at a curing energy of 400 mJ / cm². 2 The fifth dry film, 6, is 2.5 μm thick, and is then wound up to obtain a multifunctional medical dry thermal film.

[0119] Example 4

[0120] This embodiment provides a multifunctional medical dry thermal film and its preparation method. The preparation method of the multifunctional medical dry thermal film specifically includes the following steps:

[0121] S1: Behenic acid was added to deionized water at 90°C, with a mass ratio of behenic acid to deionized water of 1:10. A 3M sodium hydroxide solution was added dropwise, and the reaction proceeded for 2 hours to obtain a sodium behenate solution, with a molar ratio of sodium hydroxide to behenic acid of 1.2:1. The pH was adjusted to 8 with 2M hydrochloric acid to obtain reaction solution A. A 1.5M mixed metal solution was added dropwise, with a molar ratio of ferric chloride to copper chloride of 15:1 and a total molar ratio of behenic acid to ferric chloride to copper chloride of 3.2:1. The mixture was stirred at 80°C for 4 hours, filtered, washed, and dried to obtain an iron / copper behenate complex. The iron / copper behenate complex was mixed with a 7wt% polyvinyl alcohol aqueous solution at a mass ratio of 1:6 to obtain a dispersion. This dispersion was then ground and dispersed in a sand mill for 10 hours, with deionized water added during the grinding process to obtain an aqueous metal source dispersion with a solid content of 25%.

[0122] S2: Gallic acid and octadecylamine are added to a mixed solvent, wherein the volume ratio of tetrahydrofuran to N,N-dimethylformamide in the mixed solvent is 5:1, the molar ratio of gallic acid to octadecylamine is 1:1.2, and the mass-volume ratio of the total mass of gallic acid and octadecylamine to the mixed solvent is 1 g:8 mL. Dicyclohexylcarbodiimide catalyst is added to obtain reaction solution B, wherein the molar ratio of catalyst to gallic acid is 1.2:1. The reaction is stirred at 40℃ for 24 h, and the modified ligand is obtained by hot filtration, rotary evaporation, and recrystallization. The modified ligand is mixed with ethanol at a mass ratio of 1:1.5, and then styrene-acrylic acid copolymer emulsion is added, wherein the mass ratio of modified ligand to styrene-acrylic acid copolymer emulsion is 1:4. Deionized water is added to adjust the solid content to 35% to obtain a pre-grinding solution, which is placed in a bead mill for wet grinding for 12 h to obtain an aqueous high-steric ligand dispersion with a solid content of 30%.

[0123] S3: Rare earth chlorides were added to the second mixed solvent, and the mixture was purged with nitrogen at 160°C for 2 hours to remove water. The rare earth chlorides were obtained by mixing yttrium chloride, ytterbium chloride, and erbium chloride in a molar ratio of 78:20:2. The volume ratio of oleic acid to 1-octadecene in the second mixed solvent was 1:2. Methanol solution was added under a nitrogen atmosphere to obtain reaction solution C, in which the concentration of ammonium fluoride in the methanol solution was 0.6M, the concentration of sodium hydroxide was 0.4M, and the molar ratio of rare earth chlorides to ammonium fluoride and sodium hydroxide was 1:5:3. The mixture was heated to 310°C and reacted for 2 hours. After cooling, centrifugation, and washing, oil-soluble upconversion luminescent nanoparticles were obtained. Oil-soluble upconversion luminescent nanoparticles were dispersed in chloroform using DSPE-PEG2000 at a mass ratio of 1:1. The chloroform was removed by rotary evaporation to form a thin film. Deionized water was added and the film was ultrasonically hydrated in a 60°C water bath for 60 min to obtain an aqueous upconversion luminescent nanoparticle dispersion with a concentration of 5 mg / mL. Lanthanum hexaboride nanoparticles were added to a 2 wt.% sodium polyacrylate solution at a mass ratio of 10:1. The solution was ultrasonically broken up in an ice-water bath for 60 min to obtain a photothermal conversion dispersion with a concentration of 2 mg / mL.

[0124] S4: Prepare a highly cross-linked acrylic resin emulsion with a solid content of 20% as a barrier primer; mix mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion, and waterborne polyurethane resin at a mass ratio of 10:3:100, and degas using ultrasound to obtain a functional back coating; mix an aqueous metal source dispersion and an aqueous high-steric ligand dispersion at a solid mass ratio of 2:1, add a photothermal conversion dispersion and a leveling agent TEGO Glide 450, wherein the amount of the leveling agent added is 0.5% of the total mass of the color-developing layer coating liquid, and stir and mix evenly at 20°C to obtain a color-developing layer coating liquid, wherein the mass fraction of lanthanum hexaboride nanoparticles is 0.08% of the total solid content of the color-developing layer coating liquid; mix an aqueous UV-curable polyurethane acrylate emulsion with PMMA cross-linked microspheres with a particle size of 3μm, wherein the mass ratio of PMMA cross-linked microspheres to aqueous UV-curable polyurethane acrylate emulsion is 8:100, and add Irgacure Irgacure 2959 photoinitiator is used, with the amount of Irgacure 2959 photoinitiator being 4% of the mass of the waterborne UV-curable polyurethane acrylate emulsion. The solid content is adjusted to 30% to obtain the top protective liquid.

[0125] S5: A barrier primer is coated on the back of the blue PET substrate 1 and dried at 100℃, resulting in a first dry film 2 with a thickness of 1.5μm. A functional back coating is then coated on top and dried at 100℃, resulting in a second dry film 3 with a thickness of 3μm. An aqueous upconversion luminescent nanoparticle dispersion is coated on a predetermined area at the edge of the substrate's front side and dried, resulting in a third dry film 4 with a thickness of 1.0μm. Subsequently, a color-developing layer coating is applied to the entire front side of the substrate, pre-dried at 40℃, and finally dried at 60℃, resulting in a fourth dry film 5 with a thickness of 15μm. Finally, a top protective liquid is coated on top of the color-developing layer, dried at 80℃ for 2 minutes, and then cured using a UV lamp at a curing energy of 600mJ / cm². 2 The fifth dry film, 6 μm thick, is wound up to obtain a multifunctional medical dry thermal film.

[0126] Comparative Example 1

[0127] This comparative example provides a multifunctional medical dry thermal film and its preparation method. The difference from Example 1 is that the iron / copper berghedrosterone complex is not prepared in S1. Instead, the mixed metal solution of ferric chloride and copper chloride is directly mixed with the aqueous solution of polyvinyl alcohol to obtain an aqueous metal source dispersion. Other operation steps and process parameters are exactly the same as in Example 1.

[0128] Comparative Example 2

[0129] This comparative example provides a multifunctional medical dry thermal film and its preparation method. The difference from Example 1 is that in S2, no modified ligand is prepared. Gallic acid is directly dispersed in ethanol and then mixed with styrene-acrylic acid copolymer emulsion. Other operation steps and process parameters are exactly the same as in Example 1.

[0130] Comparative Example 3

[0131] This comparative example provides a multifunctional medical dry thermal film and its preparation method. The difference from Example 1 is that in S4, instead of preparing the aqueous metal source dispersion and the aqueous high steric hindrance ligand dispersion separately and then mixing them, the iron / copper berghedrosite complex, modified ligand, polyvinyl alcohol aqueous solution, styrene-acrylic copolymer emulsion, deionized water, photothermal conversion dispersion and leveling agent are directly added to the same sand milling system for co-milling. The resulting dispersion is directly used as the color development layer coating liquid. Other operation steps and process parameters are exactly the same as in Example 1.

[0132] Comparative Example 4

[0133] This comparative example provides a multifunctional medical dry thermal film and its preparation method. The difference from Example 1 is that no photothermal conversion dispersion is prepared, and lanthanum hexaboride nanoparticles and their dispersion are not added to the color development layer coating solution. Other operating steps and process parameters are exactly the same as in Example 1.

[0134] The performance of the multifunctional medical dry thermal films of Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0135] According to YY 1796-2021, the maximum optical density (D) of the tested sample is [not specified]. max Minimum optical density (D) min ), grayscale display capability and image resolution;

[0136] High temperature stability: Place the sample at 60℃ for 24 hours and observe for fading, deformation, or stickiness;

[0137] High humidity stability: Place the sample under 90%RH for 24 hours and observe for any fogging or discoloration;

[0138] The haze of the test sample was measured according to GB / T 2410-2008;

[0139] The test results are shown in Table 1.

[0140] Table 1: Performance test results of multifunctional medical dry thermal films in Examples 1-4 and Comparative Examples 1-4

[0141]

[0142] From the test results of Example 1 and Comparative Example 1 in Table 1, it can be seen that in D max In contrast, Comparative Example 1, due to the direct use of an aqueous solution of ferric chloride / copper chloride as the metal source, had fewer effective coordination centers available during color development, resulting in lower blackness compared to Example 1; in D minIn terms of coloring, soluble metal salts are inherently colored and readily coordinate at room temperature, resulting in increased haze. Regarding grayscale display capability, the initial background color is darker, the effective grayscale stretching range is shortened, the number of grayscale levels decreases, and the layers are not fine enough. In terms of image resolution, the high mobility of metal ions leads to diffusion at the color boundary, resulting in blurred line edges and decreased resolution. Regarding high-temperature stability, high temperatures further promote metal salt coordination and migration, manifesting as fading and deepening of the background color, with thermal stability inferior to Example 1. Regarding high-humidity stability, metal ions migrate and hydrolyze more easily under humid and hot conditions, causing haze and significant discoloration in the sample. Regarding haze, uneven coloring and local aggregation within the color layer enhance light scattering, resulting in higher haze than in Example 1.

[0143] From the test results of Example 1 and Comparative Example 2 in Table 1, it can be seen that in D max In contrast, Comparative Example 2 directly used gallic acid, and some coordination had already occurred during the coating and storage stages. This reduced the number of coordination sites that could further develop color during thermal printing, resulting in lower blackness compared to Example 1. In D... min In this respect, gallic acid is easily oxidized and reacts with Fe. 3+ Spontaneous complexation leads to a higher background color. In terms of grayscale display capability, low-density areas quickly transition to medium-high density, resulting in concentrated grayscale distribution and reduced levels. Regarding image resolution, free polyphenols diffuse within the matrix, causing slight smudging at color boundaries and decreased detail clarity. In terms of high-temperature stability, heating accelerates polyphenol oxidation and continued coordination, leading to slight fading in grayscale areas while the background continues to deepen, indicating lower thermal stability compared to Example 1. In terms of high-humidity stability, humidity promotes gallic acid water absorption and oxidation, causing slight fogging and a shift in hue towards yellowish-brown. Regarding haze, the microscopic aggregation of polyphenols and their oxidation products increases scattering, resulting in slightly higher haze than in Example 1.

[0144] From the test results of Example 1 and Comparative Example 3 in Table 1, it can be seen that in D max In terms of the co-grinding process, the iron / copper berghehendate complex and the modified ligand come into extensive contact during the grinding stage, resulting in some color development reactions occurring prematurely. This leads to insufficient available metal sources during thermal printing, resulting in lower blackness compared to Example 1. In D... min In terms of pre-development, the background haze is significantly increased; in terms of grayscale display capability, the low gray areas have been pre-colored, resulting in a narrower dynamic range and a reduced number of grayscale levels; in terms of image resolution, the size of the colorimetric units increases and their distribution is uneven, leading to rougher line edges and a decrease in resolution; in terms of high-temperature stability, the residual incomplete coordination structures continue to rearrange at high temperatures, further deepening the background color and worsening grayscale uniformity; in terms of high-humidity stability, the entry of moisture promotes the continued reaction of the residual metal source and ligands, resulting in a darker background color in local areas and poorer image stability; in terms of haze, the particle size and distribution are not as uniform as in Example 1, and the internal refractive index of the colorimetric layer is uneven, resulting in slightly higher haze.

[0145] From the test results of Example 1 and Comparative Example 4 in Table 1, it can be seen that in D max In terms of efficiency, after removing the lanthanum hexaboride photothermal filler, the utilization efficiency of the color development layer for the thermal head radiation and local thermal field decreases, resulting in insufficient promotion of the color development reaction under the same energy, and lower blackness than in Example 1; in D min In terms of overall formulation, the base haze is similar to that of Example 1, with only slight differences. Regarding grayscale display capability, the temperature rise in the low-to-medium energy zone is insufficient, resulting in a less sensitive grayscale response and a reduced number of resolvable grayscale levels. In terms of image resolution, the lack of local photothermal amplification effect leads to decreased pixel edge contrast and slightly lower resolution for fine lines. Regarding high-temperature stability, lanthanum hexaboride is a low-dosage inert filler, and its removal results in similar fading and deformation at high temperatures as in Example 1. Regarding high-humidity stability, the photothermal filler has limited impact on hygroscopic behavior, and the haze and discoloration of the sample under humid and hot conditions are not significantly different from Example 1. Regarding haze, the optical structure of the color development layer is basically the same, and the haze is similar to that of Example 1.

[0146] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A multifunctional medical dry thermal film, characterized in that, The multifunctional medical dry thermal film includes a blue PET substrate (1) and multiple dry film structures disposed on the back and front sides of the blue PET substrate (1), wherein: The back of the blue PET substrate (1) is sequentially provided with a first dry film (2) formed by a barrier primer and a second dry film (3) formed by a functional back coating liquid. The blue PET substrate (1) has a third dry film (4) formed by an aqueous upconversion luminescent nanoparticle dispersion in a preset area on the front edge, and the blue PET substrate (1) has a fourth dry film (5) formed by a color development layer coating liquid and a fifth dry film (6) formed by a top protective liquid in the entire front area. The barrier primer is a highly cross-linked acrylic resin emulsion with a solid content of 10-20%. The functional back coating liquid is prepared by mixing mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion, and water-based polyurethane resin. The color development coating solution is composed of an aqueous metal source dispersion, an aqueous high-position hindered ligand dispersion, a photothermal conversion dispersion, and a leveling agent. The top protective liquid is prepared by mixing water-based UV-curable polyurethane acrylate emulsion, PMMA cross-linked microspheres and Irgacure2959 photoinitiator; The aqueous upconversion luminescent nanoparticle dispersion is obtained by modifying oil-soluble upconversion luminescent nanoparticles with DSPE-PEG2000 and transferring them to the aqueous phase via a thin-film hydration method.

2. The multifunctional medical dry thermal film according to claim 1, characterized in that, The aqueous metal source dispersion is a dispersion with a solid content of 15-25%, comprising an iron / copper beryl sulfate complex and a polyvinyl alcohol aqueous solution. The iron / copper beryl sulfate complex is obtained by reacting behenic acid with a mixed metal solution containing ferric chloride and copper chloride under alkaline conditions. The molar ratio of ferric chloride to copper chloride in the mixed metal solution is (8-15):1, and the molar ratio of behenic acid to the total molar ratio of ferric chloride and copper chloride is (2.8-3.2):

1. The concentration of the polyvinyl alcohol aqueous solution is 5-10 wt%.

3. The multifunctional medical dry thermal film according to claim 1, characterized in that, The aqueous high-steric ligand dispersion is a dispersion with a solid content of 20-30%, comprising a modified ligand and a styrene-acrylic acid copolymer emulsion. The modified ligand is obtained by the condensation reaction of gallic acid and octadecylamine in the presence of dicyclohexylcarbodiimide. The molar ratio of gallic acid to octadecylamine is 1:(1-1.2), the molar ratio of dicyclohexylcarbodiimide to gallic acid is (1-1.2):1, and the mass ratio of the modified ligand to the styrene-acrylic acid copolymer emulsion is 1:(2-4).

4. The multifunctional medical dry thermal film according to claim 1, characterized in that, In the aqueous upconversion luminescent nanoparticle dispersion, the upconversion luminescent nanoparticles are obtained by reacting yttrium chloride, ytterbium chloride, and erbium chloride with ammonium fluoride and sodium hydroxide in a second mixed solvent composed of oleic acid and 1-octadecene. The molar ratio of yttrium chloride, ytterbium chloride, and erbium chloride is 78:20:2, the molar ratio of rare earth chloride to ammonium fluoride and sodium hydroxide is 1:(3.5-5):(2-3), the volume ratio of oleic acid to 1-octadecene in the second mixed solvent is 1:(1-2), and the mass ratio of oil-soluble upconversion luminescent nanoparticles to DSPE-PEG2000 is 1:(0.5-1).

5. A multifunctional medical dry thermal film according to claim 1, characterized in that, The photothermal conversion dispersion is a dispersion with a concentration of 0.5-2 mg / mL, composed of lanthanum hexaboride nanoparticles and sodium polyacrylate solution, wherein the mass fraction of the sodium polyacrylate solution is 0.5-2 wt.%, and the mass ratio of lanthanum hexaboride nanoparticles to sodium polyacrylate is (5-10):

1.

6. The multifunctional medical dry thermal film according to claim 1, characterized in that, The first dry film (2) has a thickness of 0.5-1.5 μm, the second dry film (3) has a thickness of 1-3 μm, the third dry film (4) has a thickness of 0.3-1.0 μm, the fourth dry film (5) has a thickness of 10-15 μm, and the fifth dry film (6) has a thickness of 2-4 μm.

7. A method for preparing a multifunctional medical dry thermal film as described in any one of claims 1-6, characterized in that, The preparation method of the multifunctional medical dry thermal film includes: S1: Behenic acid is added to deionized water, and sodium hydroxide solution is added dropwise under heating and stirring to react and obtain sodium behenic acid solution. The pH is adjusted with hydrochloric acid, and a mixed metal solution composed of ferric chloride and copper chloride is added dropwise to the sodium behenic acid solution to generate an iron / copper behenic acid complex. The iron / copper behenic acid complex is mixed with polyvinyl alcohol aqueous solution and wet-milled and dispersed in a sand mill to obtain an aqueous metal source dispersion. S2: Gallic acid and octadecylamine are added to a mixed solvent composed of tetrahydrofuran and N,N-dimethylformamide, and dicyclohexylcarbodiimide is added to carry out a condensation reaction to obtain a modified ligand; the modified ligand is mixed with ethanol and then added to a styrene-acrylic acid copolymer emulsion, and deionized water is added to adjust the solid content. The mixture is then wet-milled using a bead mill to obtain an aqueous high-steric ligand dispersion. S3: Rare earth chlorides are dissolved in a second mixed solvent, and a methanol solution containing ammonium fluoride and sodium hydroxide is added under nitrogen purging to react and obtain oil-soluble upconversion luminescent nanoparticles; the oil-soluble upconversion luminescent nanoparticles are dispersed with DSPE-PEG2000 in chloroform to form a mixed film, and after removing chloroform by rotary evaporation, deionized water is added and ultrasonically hydrated to obtain an aqueous upconversion luminescent nanoparticle dispersion; lanthanum hexaboride nanoparticles are added to a sodium polyacrylate solution and ultrasonically crushed under ice-water bath conditions to obtain a photothermal conversion dispersion; S4: Prepare a highly cross-linked acrylic resin emulsion as a barrier primer; mix mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion and waterborne polyurethane resin and ultrasonically degas to obtain a functional back coating; mix the waterborne metal source dispersion with the waterborne high-steric-barrier ligand dispersion, add the photothermal conversion dispersion and leveling agent, stir and mix evenly to obtain a color development layer coating; mix waterborne UV-curable polyurethane acrylate emulsion, PMMA cross-linked microspheres and Irgacure2959 photoinitiator, and adjust the solid content to obtain a top protective liquid; S5: The barrier primer and the functional back coating are sequentially coated on the back of the blue PET substrate (1) and dried to form a first dry film (2) and a second dry film (3); the aqueous upconversion luminescent nanoparticle dispersion is coated on the preset area of ​​the front edge of the blue PET substrate (1) and dried to form a third dry film (4); the color development coating liquid is coated on the entire front of the blue PET substrate (1) and pre-dried and finally dried to form a fourth dry film (5); the top protective liquid is coated on the fourth dry film (5) and dried, and then cured by a UV lamp box to form a fifth dry film (6), and then wound up to obtain a multifunctional medical dry thermal film.

8. The method for preparing a multifunctional medical dry thermal film according to claim 7, characterized in that, In S1: Behenic acid is added to deionized water and heated to 75-90℃. Sodium hydroxide solution with a concentration of 1-3M is added dropwise, and the reaction takes 1-2 hours to obtain sodium behenic acid solution. The pH of sodium behenic acid solution is adjusted to 7-8 with 1-2M hydrochloric acid, and then mixed metal solution is added. The mixture is stirred at 60-80℃ for 2-4 hours to generate iron / copper behenic acid complex. The iron / copper behenic acid complex is mixed with polyvinyl alcohol aqueous solution and then ground and dispersed in a sand mill for 4-10 hours.

9. The method for preparing a multifunctional medical dry thermal film according to claim 7, characterized in that, In S2: The volume ratio of tetrahydrofuran to N,N-dimethylformamide in the mixed solvent is (3-5):1, and the mass-to-volume ratio of gallic acid and octadecylamine to the mixed solvent is 1 g:(4-8) mL. The modified ligand is obtained by stirring at 25-40℃ for 12-24 h. The solid content is adjusted to 25-35%, and the wet grinding time is 6-12 h.

10. The method for preparing a multifunctional medical dry thermal film according to claim 7, characterized in that, In S3: Rare earth chlorides were purged with nitrogen at 140-160℃ for 1-2 hours to remove water. A methanol solution containing ammonium fluoride and sodium hydroxide was then added, and the mixture was heated to 280-310℃ under a nitrogen atmosphere for 1-2 hours. After cooling, centrifugation, and washing, oil-soluble upconversion luminescent nanoparticles were obtained. The oil-soluble upconversion luminescent nanoparticles and DSPE-PEG2000 formed a mixed film in chloroform, which was then ultrasonically hydrated in a water bath at 60-70℃ for 30-60 minutes to obtain an aqueous upconversion luminescent nanoparticle dispersion. The ultrasonic disruption time was 30-60 minutes. The rare earth chlorides included yttrium chloride, ytterbium chloride, and erbium chloride. The mixed solvent consisted of oleic acid and 1-octadecene.

11. The method for preparing a multifunctional medical dry thermal film according to claim 7, characterized in that, In S4: The mass ratio of the mesoporous silica, conductive polymer PEDOT:PSS aqueous dispersion, and aqueous polyurethane resin is (5-10):(1-3):

100. The aqueous metal source dispersion and the aqueous high-sterile-resistance ligand dispersion are mixed at a solid mass ratio of (1-2):

1. The leveling agent is BYK-333 or TEGO Glide 450; The PMMA cross-linked microspheres have a particle size of 1-3 μm.

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