Full-color erasable thermal sensitive paper and its preparation method

Abstract

The present application relates to a kind of full color erasable thermal sensitive paper and its preparation method.The full color erasable thermal sensitive paper of the present application includes protective layer, thermal sensitive coating, substrate arranged in turn from top to bottom;Thermal sensitive coating includes yellow thermal sensitive coating, first intermediate layer, magenta thermal sensitive coating, second intermediate layer and cyan thermal sensitive coating arranged in turn from top to bottom.The full color erasable thermal sensitive paper prepared by the present application can realize the yellow, magenta, cyan with higher color density, avoid the color density of yellow, magenta, cyan in current thermal sensitive paper not enough;It is beneficial to print out separate yellow, magenta and cyan, and also can be overlaid, after 100 times of repeated erasing, its color coordinates only have slight deviation, therefore the full erasable thermal paper of the present application can be used repeatedly, solve the serious environmental pollution and resource waste problem caused by one-time use of inkless paper in prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of printing consumables, and in particular to full-color erasable thermal photo paper and a preparation method thereof. Background Art

[0002] Zink paper is the core of Zink technology. It consists of a layer of crystals containing yellow, magenta, and cyan dyes, a protective surface coating, and a paper base. This paper enables truly inkless printing. Zink paper is produced by paper mills as large-format rolls and then cut into various sizes and specifications according to user needs. Zink paper can also be processed onto plastic sheets and self-adhesive backings, making it suitable for a wide range of applications. The crystals containing yellow, magenta, and cyan dyes within the specialized paper change color when heated, creating the different colors displayed on the paper. However, Zink paper cannot be reused, and discarded photos pollute the environment and waste resources.

[0003] At present, the erasable information storage documents based on ID cards have achieved thermal erasable writing, but their colors are single and their erasure resistance still needs to be improved. After being erased 20 times by a thermal laminator, obvious marks appear on the surface, especially its light-cured protective layer, which cannot be folded, limiting its application on ordinary paper and making it difficult to meet the demand for full-color photo paper. The ink-free photo paper prepared by current technology can only be used once. These thermal papers used to record text information or images will be treated as garbage or waste when they are no longer useful, thus causing a huge waste of resources and polluting the environment. Therefore, the development of erasable full-color photo paper is of great significance.

[0004] Research and development of full-color rewritable thermal photographic paper is relatively limited because the melting points of yellow, magenta, and cyan thermal dyes are similar, making it difficult to achieve color overlay. In view of this, the present invention provides a color rewritable thermal photographic paper based on multi-color and multi-layer overlay and a preparation method thereof. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a full-color erasable thermal photographic paper and a preparation method thereof. The full-color erasable thermal photographic paper prepared by the present invention can achieve yellow, magenta, and cyan with high color density, avoiding the insufficient color density of yellow, magenta, and cyan in current thermal photographic paper; it is conducive to printing separate yellow, magenta, and cyan, and can also perform overlay. After repeated erasure 100 times, its color coordinates only have a slight deviation. Therefore, the fully erasable thermal paper of the present invention can be reused multiple times, solving the serious environmental pollution and resource waste problems caused by the inkless photographic paper in the prior art that can only be used once.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] The first step of the present invention is to provide a full-color erasable thermal photo paper, comprising a protective layer, a thermal coating layer, and a substrate arranged in sequence from top to bottom;

[0008] The thermosensitive coating comprises a yellow thermosensitive coating, a first intermediate layer, a magenta thermosensitive coating, a second intermediate layer and a cyan thermosensitive coating arranged in sequence from top to bottom;

[0009] The yellow thermosensitive coating comprises the following raw materials in parts by weight: 10-45 parts of developer A, 2-15 parts of yellow thermosensitive dye, 30-50 parts of adhesive A, 20-30 parts of polyamide curing agent and 1-20 parts of thermal conductive additive A;

[0010] The first intermediate layer comprises the following raw materials in parts by weight: 10-50 parts of thermal insulation additive A, 30-80 parts of adhesive B, and 40-60 parts of curing agent A;

[0011] The magenta heat-sensitive coating comprises the following raw materials in parts by weight: 10-45 parts of developer B, 2-15 parts of magenta heat-sensitive dye, 30-50 parts of adhesive C, 20-30 parts of polyamide curing agent, 1-20 parts of thermal conductive agent B, and 2-15 parts of temperature regulating agent A.

[0012] The second intermediate layer comprises the following raw materials in parts by weight: 10-50 parts of thermal insulation additive B, 30-80 parts of adhesive D, and 40-60 parts of curing agent B;

[0013] The cyan thermosensitive coating comprises the following raw materials in parts by weight: 10-45 parts of a developer C, 2-15 parts of a cyan thermosensitive dye, 30-50 parts of an adhesive E, 20-30 parts of a polyamide curing agent, 1-20 parts of a thermal conductive agent C, and 2-15 parts of a temperature regulating agent B.

[0014] The beneficial effects of the present invention are as follows: (1) The present invention isolates heat through the first intermediate layer and the second intermediate layer, and adds a temperature regulating agent to adjust the color development temperature of the yellow thermal-sensitive coating, the magenta thermal-sensitive coating and the cyan thermal-sensitive coating to high, medium and low. Yellow monochrome printing is achieved by short high-temperature heating, magenta monochrome printing is achieved by short medium-temperature heating, and cyan monochrome printing is achieved by low-temperature heating. At the same time, full-color printing can be achieved by superimposing three colors.

[0015] (2) The solution of the present invention can achieve yellow, magenta, and cyan with higher color density, thereby avoiding the problem of insufficient color density of yellow, magenta, and cyan in current thermal photo paper; it is beneficial to print out separate yellow, magenta, and cyan, and is beneficial to print out high-density yellow, magenta, and cyan.

[0016] Furthermore, the color-developing temperature difference between the yellow thermosensitive coating and the magenta thermosensitive coating is greater than 25° C., and the color-developing temperature difference between the magenta thermosensitive coating and the cyan thermosensitive coating is greater than 25° C.

[0017] Furthermore, the monochrome printing time of the yellow thermosensitive coating and the magenta thermosensitive coating is less than 100 ms.

[0018] The beneficial effect of adopting the above further solution is that various distinct colors can be superimposed.

[0019] On the basis of the above technical solution, the present invention can also be improved as follows.

[0020] Furthermore, the developer A in the yellow thermosensitive coating is , wherein P=12~37; the yellow thermosensitive dye is 、 At least one of; the adhesive A is at least one of epoxy resin, polyurethane and acrylate; the thermal conductive agent A is at least one of zinc oxide, magnesium oxide and aluminum oxide.

[0021] The beneficial effect of adopting the above further solution is that the dye and the developer are mixed under heating conditions to produce a color development reaction, thereby realizing information recording.

[0022] Furthermore, the thermal insulation aid A in the first intermediate layer is at least one of zinc oxide, glass fiber, montmorillonite, Al2O3, and rare earth heat resistant agent; the adhesive B is at least one of PVA, polyacrylate and polyurethane; and the curing agent A is at least one of ethylenediamine, diethylenetriamine, and polyamide.

[0023] The beneficial effect of adopting the above further solution is that the first intermediate layer plays a heat-insulating role, preventing the magenta heat-sensitive coating from developing color when yellow is printed at high temperature.

[0024] Furthermore, the developer B in the magenta heat-sensitive coating is , wherein P=12~37; the magenta thermosensitive dye is 、 、 、 、 、 、 、 、 At least one of the following: the adhesive C is at least one of epoxy resin, polyurethane and acrylate; the thermal conductive agent B is at least one of zinc oxide, magnesium oxide and aluminum oxide; the temperature regulating agent A is at least one of naphthyl urea compounds, naphthyl amide compounds, naphthyl ester compounds and naphthyl amino acid ester compounds.

[0025] The beneficial effect of adopting the above further solution is that the dye and the developer are mixed under heating conditions to produce a color development reaction, thereby realizing information recording.

[0026] Furthermore, the thermal insulation aid B in the second intermediate layer is at least one of zinc oxide, glass fiber, montmorillonite, Al2O3, and rare earth heat resistant agent; the curing agent B is at least one of ethylenediamine, diethylenetriamine, and polyamide; and the adhesive D is at least one of PVA, polyacrylate, and polyurethane.

[0027] Furthermore, the developer C in the cyan heat-sensitive coating is , wherein P=12~37; the cyan thermosensitive dye is 、 、 、 At least one of the following: the adhesive E is at least one of epoxy resin, polyurethane and acrylate; the thermal conductive agent C is at least one of zinc oxide, magnesium oxide and aluminum oxide; the temperature regulating agent B is at least one of naphthyl urea compounds, naphthyl amide compounds, naphthyl ester compounds and naphthyl amino acid ester compounds.

[0028] The beneficial effect of adopting the above further solution is that the dye and the developer are mixed under heating conditions to produce a color development reaction, thereby realizing information recording.

[0029] Furthermore, the protective layer comprises the following raw materials in parts by weight: 10-50 parts of thermal conductive agent D, 1-10 parts of anti-ultraviolet agent, 1-5 parts of lubricant, 30-80 parts of adhesive F; and 40-60 parts of curing agent C.

[0030] The beneficial effect of adopting the above further solution is that the protective layer ensures the heat conduction effect while reducing costs.

[0031] Furthermore, the thermal conductive agent D in the protective layer is at least one of zinc oxide, MgO and Al2O3; the anti-UV agent is at least one of salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, and triazines; the lubricant is at least one of zinc stearate, mineral lubricants, silicone oil, fatty acid amide, oleic acid, polyester, synthetic ester, and carboxylic acid; the adhesive F is at least one of PVA, polyacrylate, and polyurethane; and the curing agent C is at least one of ethylenediamine and diethylenetriamine.

[0032] Furthermore, the thickness of the substrate is 100~140 μm, the thickness of the yellow thermosensitive coating is 5~8 μm, the thickness of the first intermediate layer is 2~6 μm, the thickness of the magenta thermosensitive coating is 6~10 μm, the thickness of the second intermediate layer is 2~6 μm, the thickness of the cyan thermosensitive coating is 8~14 μm, and the thickness of the protective layer is 1~3 μm.

[0033] Furthermore, the substrate is at least one of coated paper, white cardboard, kraft paper, offset paper, glassine paper, stone paper, and PVC paperboard.

[0034] A second object of the present invention is to provide a method for preparing full-color erasable thermal photo paper, comprising the following steps:

[0035] S1: Prepare yellow thermal coating liquid: dissolve developer A, yellow thermal dye, adhesive A, polyamide curing agent and thermal conductive additive A in a solvent and mix thoroughly to prepare a yellow thermal coating liquid for later use;

[0036] Magenta thermal coating liquid: dissolve developer B, magenta thermal dye, adhesive C, polyamide curing agent, thermal conductive agent B and temperature regulating agent A in a solvent and mix thoroughly to prepare a magenta thermal coating liquid for later use;

[0037] Cyan thermal coating liquid: dissolve developer C, cyan thermal dye, adhesive E, polyamide curing agent, thermal conductive agent C and temperature regulating agent B in a solvent and mix thoroughly to prepare a cyan thermal coating liquid for later use;

[0038] Protective liquid: dissolve the thermal conductive additive D, anti-ultraviolet additive, lubricant, adhesive F, and curing agent C in the solvent and mix thoroughly to prepare the protective liquid for later use;

[0039] First intermediate layer coating liquid: dissolve the heat insulation additive A, adhesive B and curing agent A in a solvent and mix them thoroughly to prepare the first intermediate layer coating liquid for later use;

[0040] Second intermediate layer coating liquid: dissolve the heat insulation additive B, adhesive D and curing agent B in a solvent and mix thoroughly to obtain the second intermediate layer coating liquid for later use;

[0041] S2: applying a cyan thermal-sensitive coating liquid on one side of the substrate and then drying it to form a cyan thermal-sensitive coating layer; applying a second intermediate layer coating liquid on the cyan thermal-sensitive coating layer and then drying it to form a second intermediate layer; applying a magenta thermal-sensitive coating liquid on the second intermediate layer and then drying it to form a magenta thermal-sensitive coating layer; applying a first intermediate layer coating liquid on the magenta thermal-sensitive coating layer and then drying it to form a first intermediate layer; applying a yellow thermal-sensitive coating liquid on the first intermediate layer and then drying it to form a yellow thermal-sensitive coating layer; finally, applying a protective liquid on the yellow thermal-sensitive coating layer and drying it to form a protective layer;

[0042] S3: The substrate, the cyan thermal-sensitive coating, the second intermediate layer, the magenta thermal-sensitive coating, the first intermediate layer, the yellow thermal-sensitive coating, and the protective layer are compounded by a coating process to obtain a full-color erasable thermal-sensitive photo paper based on multi-color and multi-layer superposition.

[0043] The present invention has the beneficial effects of: the full-color erasable thermal paper prepared by the preparation method provided by the present invention can be overlaid with colors, and its color coordinates only have a slight deviation after repeated erasure 100 times. Therefore, the fully erasable thermal paper of the present invention can be used repeatedly, solving the serious environmental pollution and resource waste problems caused by the inkless photo paper in the prior art that can only be used once. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic structural diagram of the full-color erasable thermal photo paper prepared in Example 1 of the present invention.

[0045] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0046] 1-substrate, 2-cyan heat-sensitive coating, 3-second intermediate layer, 4-magenta heat-sensitive coating, 5-first intermediate layer, 6-yellow heat-sensitive coating, 7-protective layer. DETAILED DESCRIPTION

[0047] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through regular channels.

[0048] Example 1:

[0049] , the specific preparation process of P=17 is as follows:

[0050] 11 g of p-aminophenol was dissolved in 300 mL of toluene, and 26 g of octadecyl isocyanate was added. The mixture was reacted at 60°C for 1 h. After the reaction, a solid was precipitated. A large amount of ethanol was added and the mixture was heated at 60°C to dissolve and recrystallize. The precipitated solid was cooled and filtered and dried to obtain a white solid with a melting point of 141-143°C.

[0051] The specific preparation process of naphthyl octadecyl ester is as follows:

[0052] 13 g of 1-naphthylamine was dissolved in 300 mL of toluene, and 26 g of octadecyl isocyanate was added. The mixture was reacted at 60°C for 1 h. After the reaction, a solid was precipitated. A large amount of ethanol was added and the mixture was heated at 60°C to dissolve and recrystallize. The precipitated solid was cooled and filtered and dried to obtain a white solid with a melting point of 141-143°C.

[0053] Example 2: Preparation of full-color erasable thermal photo paper

[0054] S1: Prepare liquid: Yellow heat-sensitive coating liquid: 36 parts of the yellow heat-sensitive coating liquid prepared in Example 1 , P = 17, 9 copies (Shenyang Photosensitive Chemical Research Institute), 30 parts of epoxy resin adhesive (Changchun Chemical Industry, Taiwan, China), 30 parts of polyamide curing agent (Anqing Hongtai), and 6 parts of magnesium oxide filler were dissolved in 100 parts of butyl acetate and mixed thoroughly to prepare a yellow heat-sensitive coating liquid for use;

[0055] Magenta thermal coating liquid: 24 parts of Example 1 , P = 17, 6 copies (Wuhan Photosensitive), 30 parts of epoxy resin adhesive (Changchun Chemical, Taiwan, China), 30 parts of polyamide curing agent (Anqing Hongtai), 6 parts of magnesium oxide filler and 6 parts of naphthyl octadecyl ester prepared in Example 1 were dissolved in a mixed solution of 100 parts of ethyl acetate and acetone (the mixing ratio of ethyl acetate to acetone was 2:1) and mixed thoroughly to prepare a magenta thermal coating liquid for use;

[0056] Cyan thermal coating liquid: the , P = 17, 9 copies (Shenyang Photosensitive), 30 parts of epoxy resin adhesive (Changchun Chemical, Taiwan, China), 30 parts of polyamide curing agent (Anqing Hongtai), 6 parts of magnesium oxide filler and 9 parts of naphthyl octadecyl ester prepared in Example 1 were dissolved in a mixed solution of 100 parts of ethyl acetate and acetone (mixing ratio: 2:1) and mixed thoroughly to prepare a cyan thermal-sensitive coating solution for use;

[0057] Protective solution: Dissolve 40 parts of zinc oxide, 5 parts of benzotriazole (Annaiji), 3 parts of talc, 75 parts of epoxy resin (Changchun Chemical, Taiwan, China), and 50 parts of diethylenetriamine (Annaiji) in 150 parts of butyl acetate and mix thoroughly to prepare a protective solution for later use;

[0058] First intermediate layer coating liquid: Dissolve 40 parts of zinc oxide, 75 parts of epoxy resin adhesive (Changchun Chemical, Taiwan, China) and 50 parts of polyamide curing agent (Anqing Hongtai) in 150 parts of butyl acetate and mix thoroughly to prepare the first intermediate layer coating liquid for later use;

[0059] Second intermediate layer coating liquid: Dissolve 40 parts of zinc oxide, 75 parts of epoxy resin adhesive (Changchun Chemical, Taiwan, China) and 50 parts of polyamide curing agent (Anqing Hongtai) in a mixed solution of 150 parts of ethyl acetate and acetone (mixing ratio of 2:1) and mix thoroughly to prepare the second intermediate layer coating liquid for later use;

[0060] S2: Coated paper (Yuxing Company) is used as the substrate 1, and a cyan thermal-sensitive coating liquid is applied to one side of the coated paper, followed by drying to form an 8μm cyan thermal-sensitive coating layer 2; a second intermediate layer coating liquid is applied to the cyan thermal-sensitive coating layer 2, followed by drying to form a 3μm second intermediate layer 3; a magenta thermal-sensitive coating liquid is applied to the second intermediate layer 3, followed by drying to form a 6μm magenta thermal-sensitive coating layer 4; a first intermediate layer coating liquid is applied to the magenta thermal-sensitive coating layer 4, followed by drying to form a 3μm first intermediate layer 5; a yellow thermal-sensitive coating liquid is applied to the first intermediate layer 5, followed by drying to form a 6μm yellow thermal-sensitive coating layer 6; and finally, a protective liquid is applied to the yellow thermal-sensitive coating layer 6, followed by drying to form a 3μm protective layer 7;

[0061] S3: The substrate 1, the cyan heat-sensitive coating 2, the second intermediate layer 3, the magenta heat-sensitive coating 4, the first intermediate layer 5, the yellow heat-sensitive coating 6, and the protective layer 7 are compounded by a coating process to obtain a full-color erasable heat-sensitive photo paper.

[0062] Example 3: Preparation of full-color erasable thermal photo paper

[0063] In preparing full-color erasable thermal photo paper, Example 3 differs from Example 2 only in that the raw material formula of the yellow thermal-sensitive coating 6 is changed. The remaining preparation steps, preparation conditions, and material sources are consistent with Example 2. The raw material formula of the yellow thermal-sensitive coating 6 in this embodiment is specifically shown in Table 1.

[0064] Table 1

[0065]

[0066] Comparative Example 1: Preparation of full-color erasable thermal photo paper

[0067] In preparing the full-color erasable thermal photo paper, this comparative example differs from Example 2 only in that the first intermediate layer 5 and the second intermediate layer 3 are not prepared. The remaining preparation steps, preparation conditions, and material sources are consistent with those of Example 1.

[0068] Comparative Example 2: Preparation of full-color erasable thermal photo paper

[0069] In preparing full-color erasable thermal photo paper, this comparative example differs from Example 2 only in that the protective layer 7 is not prepared. The remaining preparation steps, preparation conditions, and material sources are consistent with those of Example 1.

[0070] Comparative Example 3: Preparation of full-color erasable thermal photo paper

[0071] In preparing full-color erasable thermal photo paper, this comparative example differs from Example 2 only in the change in the raw material formula of the protective layer 7. The remaining preparation steps, preparation conditions, and material sources are consistent with Example 1. The results are shown in Table 2.

[0072] Table 2

[0073]

[0074] Comparative Example 4: Preparation of full-color erasable thermal photo paper

[0075] In preparing full-color erasable thermal photo paper, the difference between this comparative example and Example 2 lies only in the change in the thickness of the cyan thermal coating 2. The thickness of the cyan thermal coating 2 in this comparative example is 6 μm. The remaining preparation steps, preparation conditions, and material sources are consistent with those in Example 2.

[0076] Test example:

[0077] The full-color erasable thermal photo papers prepared using Examples 2-3 and Comparative Examples 1-4 were tested for their color density before erasure, first erasure efficiency, color density after 100 erasures, and 100th erasure efficiency.

[0078] Printing method: Huawei CV80 printer prints standard colors (yellow, magenta, and cyan) to test color density.

[0079] Erasing method: at 140℃, 1Kgf / cm 2 Under the pressure of , the image was heated for 1 second using a thermal laminator (9350T; Huimeng) and then erased. The retention rate was less than 10%, indicating that the reversibility was successful once.

[0080] The calculation method of erasure efficiency is as follows:

[0081] Erasing efficiency: (density of color after erasure - density of background color) / (density of printed color - density of background color) * 100%.

[0082] The experiment was repeated three times, and the results are shown in Table 3:

[0083] Table 3

[0084]

[0085] Table 3 shows that reducing the amount of developer and dye in the yellow heat-sensitive coating 6 reduces the color density of yellow. Omitting the thermal conductive additive from the protective layer reduces the color density of all colors. Without the protective layer 7, the yellow color density decreases significantly after 100 erase cycles. Reducing the thickness of the color-developing layer in the cyan heat-sensitive coating 2 also reduces the cyan color density.

[0086] In summary, the present invention realizes the coordination of the protective layer 7, the intermediate layer and the heat-sensitive coating, can perform three-color color development, and can perform erasable full-color overlay by superimposing the three colors.

[0087] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A full-color erasable thermal photo paper, characterized in that: The full-color erasable thermal photo paper comprises a protective layer, a thermal coating layer, and a substrate arranged in sequence from top to bottom; The thermosensitive coating comprises a yellow thermosensitive coating, a first intermediate layer, a magenta thermosensitive coating, a second intermediate layer and a cyan thermosensitive coating arranged in sequence from top to bottom; The yellow thermosensitive coating comprises the following raw materials in parts by weight: 10-45 parts of developer A, 2-15 parts of yellow thermosensitive dye, 30-50 parts of adhesive A, 20-30 parts of polyamide curing agent and 1-20 parts of thermal conductive additive A; The first intermediate layer comprises the following raw materials in parts by weight: 10-50 parts of thermal insulation additive A, 30-80 parts of adhesive B, and 40-60 parts of curing agent A; The magenta heat-sensitive coating comprises the following raw materials in parts by weight: 10-45 parts of developer B, 2-15 parts of magenta heat-sensitive dye, 30-50 parts of adhesive C, 20-30 parts of polyamide curing agent, 1-20 parts of thermal conductive agent B, and 2-15 parts of temperature regulating agent A. The second intermediate layer comprises the following raw materials in parts by weight: 10-50 parts of thermal insulation additive B, 30-80 parts of adhesive D, and 40-60 parts of curing agent B; The cyan heat-sensitive coating comprises the following raw materials in parts by weight: 10-45 parts of developer C, 2-15 parts of cyan heat-sensitive dye, 30-50 parts of adhesive E, 20-30 parts of polyamide curing agent, 1-20 parts of thermal conductive agent C, and 2-15 parts of temperature regulating agent B; The developer A in the yellow heat-sensitive coating is , wherein P=12~37; the yellow thermosensitive dye is 、 At least one of; the adhesive A is at least one of epoxy resin, polyurethane and acrylate; the thermal conductive agent A is at least one of zinc oxide, magnesium oxide and aluminum oxide; The thermal insulation agent A in the first intermediate layer is at least one of zinc oxide, glass fiber, montmorillonite, Al2O3, and rare earth heat-resistant agent; the adhesive B is at least one of PVA, polyacrylate, and polyurethane; the curing agent A is at least one of diisocyanate and triisocyanate; The developer B in the magenta heat-sensitive coating is , wherein P=12~37; the magenta thermosensitive dye is 、 、 、 、 、 、 、 、 At least one of the following: the adhesive C is at least one of epoxy resin, polyurethane and acrylate; the thermal conductive agent B is at least one of zinc oxide, magnesium oxide and aluminum oxide; the temperature regulating agent A is at least one of naphthyl urea compounds, naphthyl amide compounds, naphthyl ester compounds and naphthyl amino acid ester compounds; The thermal insulation aid B in the second intermediate layer is at least one of zinc oxide, glass fiber, montmorillonite, Al2O3, and rare earth heat resistant agent; the curing agent B is at least one of ethylenediamine, diethylenetriamine, and polyamide; and the adhesive D is at least one of PVA, polyacrylate, and polyurethane.

2. The full-color erasable thermal photo paper according to claim 1, characterized in that: The developer C in the cyan heat-sensitive coating is , wherein P=12~37; the cyan thermosensitive dye is 、 、 、 At least one of the following: the adhesive E is at least one of epoxy resin, polyurethane and acrylate; the thermal conductive agent C is at least one of zinc oxide, magnesium oxide and aluminum oxide; the temperature regulating agent B is at least one of naphthyl urea compounds, naphthyl amide compounds, naphthyl ester compounds and naphthyl amino acid ester compounds.

3. The full-color erasable thermal photo paper according to claim 1, characterized in that: The protective layer comprises the following raw materials in parts by weight: 10-50 parts of thermal conductive additive D, 1-10 parts of anti-ultraviolet additive, 1-5 parts of lubricant, and 30-80 parts of adhesive F; Curing agent C 40~60 parts.

4. The full-color erasable thermal photo paper according to claim 3, characterized in that: The thermal conductive agent D in the protective layer is at least one of zinc oxide, MgO and Al2O3; the anti-UV agent is at least one of salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, and triazines; the lubricant is at least one of zinc stearate, mineral lubricants, silicone oil, fatty acid amide, oleic acid, polyester, synthetic ester, and carboxylic acid; the adhesive F is at least one of PVA, polyacrylate, and polyurethane; and the curing agent C is at least one of ethylenediamine and diethylenetriamine.

5. The full-color erasable thermal photo paper according to claim 1, characterized in that: The thickness of the substrate is 100-140 μm, the thickness of the yellow thermosensitive coating is 5-8 μm, the thickness of the first intermediate layer is 2-6 μm, the thickness of the magenta thermosensitive coating is 6-10 μm, the thickness of the second intermediate layer is 2-6 μm, the thickness of the cyan thermosensitive coating is 8-14 μm, and the thickness of the protective layer is 1-3 μm.

6. A method for preparing full-color erasable thermal photographic paper according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: S1: Prepare yellow thermal coating liquid: dissolve developer A, yellow thermal dye, adhesive A, polyamide curing agent and thermal conductive additive A in a solvent and mix thoroughly to prepare a yellow thermal coating liquid for later use; Magenta thermal coating liquid: dissolve developer B, magenta thermal dye, adhesive C, polyamide curing agent, thermal conductive agent B and temperature regulating agent A in a solvent and mix thoroughly to prepare a magenta thermal coating liquid for later use; Cyan thermal coating liquid: dissolve developer C, cyan thermal dye, adhesive E, polyamide curing agent, thermal conductive agent C and temperature regulating agent B in a solvent and mix thoroughly to prepare a cyan thermal coating liquid for later use; Protective liquid: dissolve the thermal conductive additive D, anti-ultraviolet additive, lubricant, adhesive F, and curing agent C in the solvent and mix thoroughly to prepare the protective liquid for later use; First intermediate layer coating liquid: dissolve the heat insulation additive A, adhesive B and curing agent A in a solvent and mix thoroughly to obtain the first intermediate layer coating liquid for later use; Second intermediate layer coating liquid: dissolve the heat insulation additive B, adhesive D and curing agent B in a solvent and mix thoroughly to obtain the second intermediate layer coating liquid for later use; S2: applying a cyan thermal-sensitive coating liquid on one side of the substrate and then drying it to form a cyan thermal-sensitive coating layer; applying a second intermediate layer coating liquid on the cyan thermal-sensitive coating layer and then drying it to form a second intermediate layer; applying a magenta thermal-sensitive coating liquid on the second intermediate layer and then drying it to form a magenta thermal-sensitive coating layer; applying a first intermediate layer coating liquid on the magenta thermal-sensitive coating layer and then drying it to form a first intermediate layer; applying a yellow thermal-sensitive coating liquid on the first intermediate layer and then drying it to form a yellow thermal-sensitive coating layer; finally, applying a protective liquid on the yellow thermal-sensitive coating layer and drying it to form a protective layer; S3: The substrate, the cyan thermal-sensitive coating, the second intermediate layer, the magenta thermal-sensitive coating, the first intermediate layer, the yellow thermal-sensitive coating, and the protective layer are compounded by a coating process to obtain a full-color erasable thermal-sensitive photo paper based on multi-color and multi-layer superposition.

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