Double-layered two-color erasable thermal paper and preparation method thereof

Abstract

The present invention relates to a double-layered, two-color erasable thermal paper and a preparation method thereof, and relates to the technical field of printing consumables. The two-color erasable thermal paper of the present invention comprises a protective layer, a thermal coating, and a substrate arranged in sequence from top to bottom; the thermal coating comprises a red thermal coating and a black thermal coating arranged in sequence from top to bottom. The red thermal coating comprises the following raw materials: a color developer A, a red thermal dye, a cosolvent A, an erasing aid A, an epoxy resin adhesive, a polyamide curing agent, and a zinc oxide filler; the black thermal coating comprises the following raw materials: a color developer B, a black thermal dye, a cosolvent B, an erasing aid B, an epoxy resin adhesive, a polyamide curing agent, and a zinc oxide filler. The two-color erasable thermal paper of the present invention has a high color density, does not overlap and bleed after repeated erasure, can be completely erased, and can be repeatedly erasable.

Description

Technical Field

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

[0002] Thermal recording compounds are formed by the color reaction between electron-donating color-forming compounds (leuco dyes) and electron-accepting compounds (developers). With the continuous development of thermal technology, coating technology, and printing equipment, they have now been widely used in various scenarios of people's food, clothing, housing, transportation, and work. In particular, they have a large market size in variable information fields such as shopping mall cashiers, entertainment tickets, supermarket labels, express delivery labels, medical electrocardiograms, movie tickets, boarding passes, warehousing and logistics transportation.

[0003] Two-color non-erasable thermal paper has been commercially used, but the two-color non-erasable thermal paper prepared with 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 used, resulting in a huge waste of resources and pollution to the environment. Therefore, the development of erasable two-color thermal paper is of great significance.

[0004] However, existing erasable two-color thermal paper has the following disadvantages: (1) repeated erasure may cause the red and black colors to overlap and bleed; (2) it is difficult to completely erase. Summary of the Invention

[0005] To address the above-mentioned technical problems, the present invention provides a double-layered, dual-color erasable thermal paper and a method for preparing the same. The dual-color erasable thermal paper prepared by the present invention comprises a protective layer, a thermal coating, and a substrate. The present invention achieves the production of high-density erasable red and black dual-color thermal paper. Repeated erasure prevents the red and black colors from overlapping and bleeding, allowing for complete erasure and multiple rewritability.

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

[0007] The first object of the present invention is to provide a double-layered, two-color erasable thermal paper, comprising a protective layer, a thermal coating, and a substrate arranged in sequence from top to bottom; the thermal coating comprises a red thermal coating and a black thermal coating arranged in sequence from top to bottom;

[0008] The red heat-sensitive coating comprises the following raw materials: 10-25 parts of developer A, 2-6 parts of red heat-sensitive dye, 1-2 parts of cosolvent A, 1-2 parts of erasing aid A, 30-50 parts of epoxy resin adhesive, 30-50 parts of polyamide curing agent, and 3-8 parts of zinc oxide filler;

[0009] The black thermosensitive coating comprises the following raw materials: 35-40 parts of developer B, 2-10 parts of black thermosensitive dye, 1-2 parts of cosolvent B, 1-2 parts of erasing aid B, 27-32 parts of epoxy resin adhesive, 27-32 parts of polyamide curing agent, and 4-10 parts of zinc oxide filler.

[0010] The beneficial effects of the present invention are as follows: the two-color erasable thermal paper prepared by the present invention includes a protective layer, a thermal coating, and a substrate; a cosolvent and an erasing aid are added to the red thermal coating and the black thermal coating to achieve a two-color printing temperature difference and low melting point printing, and can achieve the phenomenon of red and black overlapping and bleeding after repeated erasure, thereby improving the printing color density and repeated erasability of the thermal coating.

[0011] Furthermore, the developer A comprises 、 At least one of the Where r=2~11, s=12~30, Medium r = 2~11, s = 12~30;

[0012] The developer B includes 、 At least one of the Where r=2~11, s=12~30, In r=2~11, s=12~30.

[0013] The beneficial effect of adopting the above further solution is that: the present invention adds a high color density developer to the heat-sensitive coating to achieve high color density of the color development layer printing.

[0014] Further, the cosolvent A and the cosolvent B are , where n=3~17.

[0015] Furthermore, the erasing aid A and the erasing aid B are , where m=3~17, n=3~17.

[0016] The beneficial effect of adopting the above further scheme is: adding co-solvents and erasing aids to the thermal sensitive coating to achieve two-color printing temperature difference and low melting point printing, and there will be no overlapping and bleeding of red and black colors after repeated erasure, thereby improving the printing color density and repeated erasability of the thermal sensitive coating.

[0017] Further, the red thermosensitive dye comprises 、 、 、 、 、 、 At least one of;

[0018] The black thermosensitive dye comprises 、 、 、 、 、 At least one of .

[0019] Furthermore, the protective layer includes the following raw materials: 30-50 parts of thermal conductive additive, 1-10 parts of anti-ultraviolet additive, 1-5 parts of lubricant, 75 parts of adhesive; and 30-70 parts of curing agent.

[0020] The beneficial effects of adopting the above further solution are: the protective layer is waterproof and gas-proof, resistant to ultraviolet rays, and reduces costs while ensuring the heat conduction effect.

[0021] Furthermore, the anti-UV additive includes at least one of salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, and triazines; the lubricant includes at least one of zinc stearate, mineral lubricants, silicone oil, fatty acid amide, oleic acid, polyester, synthetic ester, and carboxylic acid; the adhesive includes at least one of PVA, polyacrylate, and polyurethane; and the thermal conductive additive includes at least one of ZnO, MgO, and Al2O3.

[0022] Furthermore, the substrate includes at least one of coated paper, white cardboard, kraft paper, offset paper, glassine paper and stone paper.

[0023] Preferably, the substrate is PVC cardboard.

[0024] Furthermore, the thickness of the red thermosensitive coating is 6 μm to 10 μm; the thickness of the black thermosensitive coating is 5 μm to 12 μm; the thickness of the protective layer is 1 μm to 4 μm; and the thickness of the substrate is 10 μm to 14 μm.

[0025] The beneficial effect of adopting the above further solution is that it is conducive to improving the color density and purity of the red and black two-color thermal sensitive coating.

[0026] A second object of the present invention is to provide a method for preparing a double-layered, dual-color erasable thermal paper, characterized in that the preparation method comprises the following steps:

[0027] S1: Red thermal coating liquid: dissolve developer A in a solvent, then add red thermal dye, cosolvent A, erasing aid A, epoxy resin adhesive, polyamide curing agent, and zinc oxide filler, mix and dissolve together to prepare a red thermal coating liquid for later use;

[0028] Black thermal coating liquid: dissolve the developer B in the solvent, then add the black thermal dye, cosolvent B, erasing aid B, epoxy resin adhesive, polyamide curing agent, and zinc oxide filler, mix and dissolve them together to make a black thermal coating liquid for later use;

[0029] Protective liquid: dissolve the thermal conductive additive, anti-ultraviolet additive, lubricant, adhesive and curing agent in a solvent to prepare a protective liquid for standby use;

[0030] S2: applying the black heat-sensitive coating liquid on a substrate, heating and drying to obtain a black heat-sensitive coating; applying the red heat-sensitive coating liquid on the black heat-sensitive coating, heating and drying to obtain a red heat-sensitive coating;

[0031] Applying the protective liquid on the red heat-sensitive coating, heating and drying to obtain a protective layer;

[0032] S3: Compounding the substrate, the heat-sensitive coating, and the protective layer through a hot pressing process to obtain a double-layered two-color erasable thermal paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of red and black dual-color erasable thermal paper prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention.

[0034] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0035] 1-substrate, 2-black thermal sensitive coating, 3-red thermal sensitive coating, 4-protective layer. DETAILED DESCRIPTION

[0036] 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.

[0037] Example 1: Preparation of double-layered dual-color erasable thermal paper

[0038] S1: Red thermal coating liquid: 24 parts Dissolved in 100 parts of butyl acetate (Changsha Yiheng Glass Equipment Co., Ltd.), then added 6 parts of red thermosensitive dye (Shenyang Photosensitive Chemical Research Institute Co., Ltd.), 2 copies , 2 servings 30 parts of epoxy resin adhesive (Heze Deyuan Chemical Co., Ltd.), 30 parts of polyamide curing agent (Guangdong Wengjiang Chemical Reagent Co., Ltd.), and 6 parts of zinc oxide (Annaiji) filler were mixed and dissolved together to prepare a red thermal coating liquid for later use;

[0039] Black thermal coating liquid: 36 parts Dissolve in 100 parts of butyl acetate (Changsha Yiheng Glass Equipment Co., Ltd.), then add 9 parts of black thermal dye (Annage), 、 30 parts of epoxy resin adhesive (Heze Deyuan Chemical Co., Ltd.), 30 parts of polyamide curing agent (Guangdong Wengjiang Chemical Reagent Co., Ltd.), and 6 parts of zinc oxide (Annaiji) filler were mixed and dissolved together to prepare a black thermal coating liquid for later use;

[0040] Protective solution: Dissolve 40 parts of zinc oxide (Annaiji), 5 parts of benzotriazole (Annaiji), 3 parts of talc (Annaiji), 75 parts of epoxy resin adhesive resin (Heze Deyuan Chemical Co., Ltd.), and 50 parts of polyamide curing agent (Guangdong Wengjiang Chemical Reagent Co., Ltd.) in 100 parts of butyl acetate (Changsha Yiheng Huabo Equipment Co., Ltd.) to prepare a protective solution for later use;

[0041] S2: applying the black thermosensitive coating liquid on substrate 1 and drying it in an oven at 100°C to obtain a black thermosensitive coating 2; applying the red thermosensitive coating liquid on the black thermosensitive coating 2 and drying it in an oven at 100°C to obtain a red thermosensitive coating 3, wherein the thickness of the red thermosensitive coating 3 is 6 μm and the thickness of the black thermosensitive coating 2 is 6 μm;

[0042] The protective liquid is applied on the red heat-sensitive coating 3 and then heated and dried in an oven at 100° C. to obtain a protective layer 4;

[0043] S3: The substrate 1 (coated paper), the black thermal-sensitive coating 2, the red thermal-sensitive coating 3, and the protective layer 4 are compounded by a hot pressing process (hot pressing temperature 200°C, pressure 1 MPa) to obtain a double-layered two-color erasable thermal paper.

[0044] Example 2: Preparation of double-layered dual-color erasable thermal paper

[0045] The only difference between this embodiment and embodiment 1 is that the solvent A for preparing the red thermosensitive coating and the solvent B for preparing the black thermosensitive coating are replaced by The remaining raw materials and steps are the same as those in Example 1.

[0046] Example 3: Preparation of double-layered dual-color erasable thermal paper

[0047] The only difference between this embodiment and embodiment 1 is that the solvent A for preparing the red thermosensitive coating and the solvent B for preparing the black thermosensitive coating are replaced by The remaining raw materials and steps are the same as those in Example 1.

[0048] Example 4: Preparation of double-layered dual-color erasable thermal paper

[0049] The only difference between this embodiment and embodiment 1 is that the solvent A for preparing the red thermosensitive coating and the solvent B for preparing the black thermosensitive coating are replaced by The remaining raw materials and steps are the same as those in Example 1.

[0050] Comparative Example 1: Preparation of double-layered two-color erasable thermal paper

[0051] The only difference between this comparative example and Example 1 is that the erasing aid A for preparing the red heat-sensitive coating and the erasing aid B for preparing the black heat-sensitive coating are both replaced with butyl octadecyl urea. The remaining raw materials and steps are the same as those in Example 1.

[0052] Comparative Example 2: Preparation of double-layered two-color erasable thermal paper

[0053] The only difference between this comparative example and Example 1 is that the erasing aid A for preparing the red heat-sensitive coating and the erasing aid B for preparing the black heat-sensitive coating are both replaced with octyl octadecyl urea. The remaining raw materials and steps are the same as those in Example 1.

[0054] Comparative Example 3: Preparation of double-layered two-color erasable thermal paper

[0055] The only difference between this comparative example and Example 1 is that the erasing aid A for preparing the red heat-sensitive coating and the erasing aid B for preparing the black heat-sensitive coating are both replaced with dodecyl octadecyl urea. The remaining raw materials and steps are the same as those in Example 1.

[0056] Test example:

[0057] The color density and erasure efficiency of the two-color erasable thermal papers prepared in Examples 1-4 and Comparative Examples 1-3 were tested before erasure and after erasing 100 times.

[0058] Printing method: Print on a Zebra printer (Zebra105SPlus (300 DPI); Shanghai Zhenao Technology and Trade Co., Ltd.), with a red print density of 20 and a black print density of 30.

[0059] Erasing method: Erasing was performed in a thermal laminator (model: zx-1250, Shandong Zhixin Automation Equipment Co., Ltd.).

[0060] The calculation method of erasure efficiency is as follows:

[0061] Erasing efficiency = (color density after erasure - background color density) / (printing color density - background color density) * 100%.

[0062] Table 1

[0063]

[0064] From Table 1, we can get:

[0065] The color density of the two-color erasable thermal paper prepared in Examples 1-4 only deviated slightly after repeated erasure 100 times, while the color density of the two-color erasable thermal paper prepared in Comparative Examples 1-3 deviated more than that of Examples 1-4 after repeated erasure 100 times, and the erasure efficiency was reduced.

[0066] In summary, the present invention realizes the preparation of high color density erasable red and black two-color thermal paper, and after repeated erasure, there will be no phenomenon of overlapping and bleeding of the red and black two-color, and the paper can be completely erased, thus achieving repeated erasure.

[0067] 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 double-layered, two-color erasable thermal paper, characterized in that: The two-color erasable thermal paper comprises a protective layer, a thermal coating, and a substrate arranged in sequence from top to bottom; the thermal coating comprises a red thermal coating and a black thermal coating arranged in sequence from top to bottom; The red heat-sensitive coating comprises the following raw materials: 10-25 parts of developer A, 2-6 parts of red heat-sensitive dye, 1-2 parts of cosolvent A, 1-2 parts of erasing aid A, 30-50 parts of epoxy resin adhesive, 30-50 parts of polyamide curing agent, and 3-8 parts of zinc oxide filler; The black thermosensitive coating comprises the following raw materials: 35-40 parts of developer B, 2-10 parts of black thermosensitive dye, 1-2 parts of cosolvent B, 1-2 parts of erasing aid B, 27-32 parts of epoxy resin adhesive, 27-32 parts of polyamide curing agent, and 4-10 parts of zinc oxide filler; The developer A comprises 、 At least one of the Where r=2~11, s=12~30, Medium r = 2~11, s = 12~30; The developer B includes 、 At least one of the Where r=2~11, s=12~30, Medium r = 2~11, s = 12~30; The cosolvent A and the cosolvent B are , where n=3~17; The erasing aid A and the erasing aid B are , where m=3~17, n=3~17.

2. The double-layered, dual-color erasable thermal paper according to claim 1, characterized in that: The red thermosensitive dye comprises 、 、 、 、 、 、 At least one of; The black thermosensitive dye comprises 、 、 、 、 、 At least one of .

3. The double-layered, dual-color erasable thermal paper according to claim 1, characterized in that: The protective layer comprises the following materials: 30-50 parts of thermal conductive agent, 1-10 parts of anti-ultraviolet agent, 1-5 parts of lubricant, 75 parts of adhesive; 30-70 parts of curing agent.

4. The double-layered, dual-color erasable thermal paper according to claim 3, characterized in that: The anti-UV additive includes at least one of salicylates, benzophenones, benzotriazoles, substituted acrylonitriles, and triazines; the lubricant includes at least one of zinc stearate, mineral lubricants, silicone oil, fatty acid amide, oleic acid, polyester, synthetic ester, and carboxylic acid; the adhesive includes at least one of PVA, polyacrylate, and polyurethane; and the thermal conductive additive includes at least one of ZnO, MgO, and Al2O3.

5. The double-layered, dual-color erasable thermal paper according to claim 1, characterized in that: The substrate includes at least one of coated paper, white cardboard, kraft paper, offset paper, glassine paper and stone paper.

6. The double-layered, dual-color erasable thermal paper according to claim 1, characterized in that: The thickness of the red thermosensitive coating is 6 μm to 10 μm; the thickness of the black thermosensitive coating is 5 μm to 12 μm; the thickness of the protective layer is 1 μm to 4 μm; and the thickness of the substrate is 10 μm to 14 μm.

7. A method for preparing a double-layered, dual-color erasable thermal paper according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1: Red thermal coating liquid: dissolve developer A in a solvent, then add red thermal dye, cosolvent A, erasing aid A, epoxy resin adhesive, polyamide curing agent, and zinc oxide filler, mix and dissolve together to prepare a red thermal coating liquid for later use; Black thermal coating liquid: dissolve the developer B in the solvent, then add the black thermal dye, cosolvent B, erasing aid B, epoxy resin adhesive, polyamide curing agent, and zinc oxide filler, mix and dissolve them together to make a black thermal coating liquid for later use; Protective liquid: dissolve the thermal conductive additive, anti-ultraviolet additive, lubricant, adhesive and curing agent in a solvent to prepare a protective liquid for standby use; S2: applying the black heat-sensitive coating liquid on a substrate, heating and drying to obtain a black heat-sensitive coating; applying the red heat-sensitive coating liquid on the black heat-sensitive coating, heating and drying to obtain a red heat-sensitive coating; Applying the protective liquid on the red heat-sensitive coating, heating and drying to obtain a protective layer; S3: Compounding the substrate, the heat-sensitive coating, and the protective layer through a hot pressing process to obtain a double-layered two-color erasable thermal paper.

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