Two-color thermosensitive erasable paper based on developer combination design and its preparation method

Abstract

The present invention relates to a two-color thermosensitive erasable paper based on the design of chromogenic agent matching and a preparation method thereof, and relates to the technical field of printing consumables. The two-color erasable thermosensitive paper includes a thermosensitive coating, and the thermosensitive coating includes a red thermosensitive coating and a black thermosensitive coating arranged in sequence from top to bottom. The chromogenic temperature difference between the red thermosensitive coating and the black thermosensitive coating is greater than 30 °C; the components of the red thermosensitive coating include a low-temperature chromogenic agent and an erasing aid I; the components of the black thermosensitive coating include a high-temperature chromogenic agent and an erasing aid II. Through the structural matching design of the low-temperature chromogenic agent in the red thermosensitive coating and the high-temperature chromogenic agent in the black thermosensitive coating, the chromogenic temperature difference between different thermosensitive coatings is realized to achieve color overlay; combined with the erasing aid, its efficient erasing is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of printing consumables, and particularly to a two-color thermosensitive erasable paper based on the design of chromogenic agent matching and a preparation method thereof. Background Art

[0002] At present, the consumption of paper is huge, which will cause climate change and global warming. With the enhancement of environmental awareness, in order to overcome the above economic and environmental problems, reusable rewritable paper has been developed, which is more environmentally friendly than traditional ink printing.

[0003] At present, the erasable paper on the market is mainly single-colored, which is difficult to meet the needs of office and meeting paper. However, two-color or multi-color erasable, especially the relatively low-cost erasable two-color thermosensitive paper, has not been reported. In view of this, the present invention provides a two-color thermosensitive erasable paper based on the design of chromogenic agent matching and a preparation method thereof. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a two-color thermosensitive erasable paper based on the design of chromogenic agent matching and a preparation method thereof. The purpose is to achieve a temperature difference of more than 30 °C between the upper and lower thermosensitive coatings through the design of the molecular structure of the chromogenic agent, so as to achieve color overlay.

[0005] The technical solution for the present invention to solve the above technical problems is as follows:

[0006] In the first aspect, a two-color thermosensitive erasable paper based on the design of chromogenic agent matching, the two-color erasable thermosensitive paper includes a thermosensitive coating, and the thermosensitive coating includes a red thermosensitive coating and a black thermosensitive coating arranged in sequence from top to bottom. The chromogenic temperature difference between the red thermosensitive coating and the black thermosensitive coating is greater than 30 °C; the components of the red thermosensitive coating include a low-temperature chromogenic agent and erasing aid I; the components of the black thermosensitive coating include a high-temperature chromogenic agent and erasing aid II.

[0007] The beneficial effects of the present invention are: through the design of the structure of the low-temperature chromogenic agent in the red thermosensitive coating and the structure of the high-temperature chromogenic agent in the black thermosensitive coating, the chromogenic temperature difference between different thermosensitive coatings is achieved, and color overlay is realized; combined with the erasing aid, its efficient erasing is realized.

[0008] On the basis of the above technical solution, the present invention can also be improved as follows.

[0009] Further, the mass percentage content of the erasing aid I in the low-temperature chromogenic agent is 30% to 50%; the mass percentage content of the erasing aid II in the high-temperature chromogenic agent is 20% to 50%.

[0010] The beneficial effect of adopting the above further solution is: the erasing performance within this dosage range is good.

[0011] Furthermore, the low-temperature developer includes at least one of PU-18 and PC-19; the erasing aid I includes at least one of ethylene glycol, polypropylene glycol, and stearamide; the structural formulas of PU-18 and PC-19 are as follows:

[0012]

[0013] Preferably, the low-temperature developer is PU-18 and PC-19, and the mass ratio is 1:1.

[0014] The beneficial effect of adopting the above further solution is: the color development effect is optimal.

[0015] Furthermore, the high-temperature developer is at least one of General Formulas I-II, and the structures of General Formulas I-II are as follows:

[0016] In General Formula I, r is 2-8, and s is 12-30. In General Formula II, r is 2-8, and s is 12-30;

[0017] The erasing aid II includes at least one of polyethylene glycol, polypropylene glycol, stearamide, OUN-18, and Structural Formula III, and the Structural Formula III is as follows:

[0018]

[0019] The beneficial effect of adopting the above further solution is: the erasing effect is good and the cost is relatively low.

[0020] Furthermore, the high-temperature developer is at least one of Formula I-1 and Formula II-1, and the structure of Formula I-1 is as follows: The structure of Formula II-1 is as follows:

[0021]

[0022] Furthermore, the red thermosensitive coating includes the following specific components by weight: 30-50 parts of low-temperature developer, 10-40 parts of erasing aid I, 8-20 parts of thermosensitive dye, 40-60 parts of adhesive resin I, and 20-40 parts of filler.

[0023] Preferably, the thermosensitive dye I includes at least one of scarlet red, pink, and orange red; the structural formulas are as follows:

[0024] The adhesive resin I includes at least one of PVA, water-based polyacrylate, and water-based polyurethane; the filler I includes at least one of calcium carbonate, montmorillonite, and talcum powder.

[0025] Further, the black thermosensitive coating comprises the following specific components by weight: 30-50 parts of high-temperature developer, 10-40 parts of erasing aid II, 8-20 parts of thermosensitive dye II, 40-60 parts of adhesive resin II, and 20-40 parts of filler II.

[0026] Preferably, the thermosensitive dye II includes at least one of ODB2, s205, and b15; the adhesive resin II includes at least one of PVA, waterborne polyacrylate, and waterborne polyurethane; the filler II includes at least one of calcium carbonate and talcum powder.

[0027] Further, the two-color erasable thermosensitive paper further includes a protective layer, a bottom layer, and a substrate. The protective layer is provided on the red thermosensitive coating, the bottom layer is provided under the black thermosensitive coating, and the bottom layer is provided on the substrate;

[0028] The protective layer comprises the following specific components by weight: 3-8 parts of ultraviolet-resistant aid, 5-10 parts of lubricant, and 80-95 parts of adhesive resin III;

[0029] Preferably, the ultraviolet-resistant aid includes at least one of benzophenone and benzotriazole; the lubricant includes at least one of zinc stearate, silicone oil, fatty acid amide, oleic acid, and polyester; the adhesive resin III includes at least one of PVA, waterborne polyacrylate, and waterborne polyurethane.

[0030] The bottom layer comprises the following specific components by weight: 70-90 parts of adhesive resin IV, 15-25 parts of heat-insulating filler, and 5-15 parts of whitening agent.

[0031] Preferably, the adhesive resin IV includes at least one of PVA, waterborne polyacrylate, and waterborne polyurethane; the heat-insulating filler includes glass microspheres and silica aerogel; the whitening agent includes at least one of TiO2 and MgO.

[0032] Among them, the substrate is a paper substrate, preferably a PVC cardboard.

[0033] Further, the thickness of the protective layer is 3-4um, the thickness of the red thermosensitive coating is 2-3um, the thickness of the black thermosensitive coating is 2-3um, and the thickness of the bottom layer is 1-3um.

[0034] In the second aspect, a preparation method of the two-color thermosensitive erasable paper based on the developer combination design includes the following steps:

[0035] S1: Prepare the components of the bottom layer into a coating solution, coat the coating solution on the substrate, and dry it to obtain the bottom layer on the substrate;

[0036] S2: Prepare the coating liquids for the red thermosensitive coating and the black thermosensitive coating respectively by mixing their respective components; successively coat the coating liquid for the red thermosensitive coating and the coating liquid for the black thermosensitive coating on the primer coat, and then dry them to obtain the thermosensitive coating.

[0037] S3: Prepare the coating liquid for the protective layer by mixing its components, coat it on the thermosensitive coating, and then dry it to obtain the protective layer.

[0038] S4: Compose the substrate, the primer coat, the thermosensitive coating, and the protective layer through a hot pressing process to obtain the two-color thermosensitive erasable paper designed based on the developer combination. Description of the Drawings

[0039] Figure 1 This is the physical diagram of the two-color of the present invention;

[0040] Figure 2 This is the schematic diagram of the two-color thermosensitive erasable paper of the present invention Figure Ⅰ ;

[0041] Figure 3 This is the schematic diagram of the two-color thermosensitive erasable paper of the present invention Figure Ⅱ . Detailed Embodiments

[0042] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those technical or conditions not specified in the examples, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be purchased through regular channels.

[0043] The raw materials used in the following examples: except for the high-temperature developer and the low-temperature developer which are independently designed in the experiment, the rest are all conventional products purchased through regular channels.

[0044] The synthesis route of the low-temperature developer in the following example is as follows: Octadecyl isocyanate and p-aminophenol are added to a beaker containing toluene, and the reaction is carried out at 60 °C in a water bath until it cannot be stirred anymore, then filtered by suction, recrystallized, and dried to obtain the developer.

[0045] The synthetic route of the high-temperature developer is as follows: First step: 13 g of 6-aminohexanoic acid is dissolved in 200 mL of toluene, 29 g of octadecyl isocyanate is added, and the reaction is carried out at 60 °C for 10 h, and the reaction is carried out overnight; after the reaction is completed, a large amount of ethanol is added, and the mixture is heated and dissolved at 60 °C for recrystallization, cooled to precipitate a solid, and filtered and dried to obtain a white solid; Second step: 15 g of the developer intermediate is dissolved in 200 mL of DMF, 23 g of PyBOP and 16 mL of DIEA are added, and the reaction is carried out at 40 °C for 15 min, then 4.5 g of 4-aminohydroxyphenethylamine is added, and the reaction is carried out at 40 °C for 16 h, and the reaction is carried out overnight. After the reaction is completed, a white solid is obtained by filtration, a large amount of ethanol is added, and the mixture is heated and dissolved at 60 °C for recrystallization, cooled to precipitate a solid, and filtered and dried to obtain a white solid.

[0046] Example 1:

[0047] This example relates to a two-color thermosensitive erasable paper based on the design of the developer combination. The two-color erasable thermosensitive paper is provided with a protective layer, a red thermosensitive coating, a black thermosensitive coating, a bottom coating and a substrate arranged from top to bottom ( Figures 1-3 );

[0048] The protective layer includes the following specific components by weight: 8 parts of ultraviolet-resistant auxiliary (benzotriazole), 8 parts of polyethylene wax emulsion, 85 parts of PVA adhesive resin; the thickness is controlled at 3-4 um;

[0049] The red thermosensitive coating includes the following specific components by weight: 25 parts of low-temperature developer, 10 parts of polyethylene glycol, 15 parts of scarlet red, 35 parts of PVA adhesive resin and 10 parts of calcium carbonate; the thickness is controlled at 2-3 um;

[0050] The black thermosensitive coating includes the following specific components by weight: 25 parts of high-temperature developer, 10 parts of polyethylene glycol, 15 parts of black thermosensitive dye (ODB2), 35 parts of PVA adhesive resin and 12 parts of calcium carbonate; the thickness is controlled at 2-3 um;

[0051] The bottom coating includes the following specific components by weight: 80 parts of PVA adhesive resin, 15 parts of glass microspheres, 5 parts of TiO2; the thickness is controlled at 2-4 um.

[0052] The preparation method of the two-color thermosensitive erasable paper based on the design of the developer combination involved in this example includes the following steps:

[0053] S1: Prepare the components of the bottom coating into a coating solution, coat the coating solution on the substrate, and dry it to obtain the bottom coating on the substrate;

[0054] S2: Prepare the coating liquids of the red thermosensitive coating from the respective components of the red thermosensitive coating; prepare the coating liquids of the black thermosensitive coating from the respective components of the black thermosensitive coating; sequentially coat the coating liquid of the red thermosensitive coating and the coating liquid of the black thermosensitive coating on the primer layer, and dry to obtain the thermosensitive coating;

[0055] S3: Prepare the coating liquid of the protective layer from the respective components of the protective layer, coat it on the thermosensitive coating, and dry to obtain the protective layer;

[0056] S4: Composite the substrate, primer layer, thermosensitive coating, and protective layer through a hot pressing process to obtain the two-color thermosensitive erasable paper based on the design of the color developer combination.

[0057] Example 2:

[0058] In this example, the protective layer is controlled to be 4 - 5 μm, and the others are the same as in Example 1.

[0059] Example 3:

[0060] In this example, the red thermosensitive coating is controlled to be 2 - 3 μm; the black thermosensitive coating is controlled to be 4 - 6 μm, and the others are the same as in Example 1.

[0061] Control Example: 1

[0062] Both the red and black thermosensitive layers use low-temperature color developers, and the rest are the same. It is found that it is difficult to present two colors.

[0063] Control Example: 2

[0064] Both the red and black thermosensitive layers use high-temperature color developers, and the rest are the same. It is found that it is difficult to present two colors.

[0065] Test Example:

[0066] (1) Detection method for the static saturation color density before ethanol resistance and after 3 h of ethanol resistance experiment:

[0067] First, place the specimen on a flat glass with the coloring surface facing up, then place the pipette on the saturatedly colored specimen and suck 1.0 mL of ethanol into the pipette. After standing at room temperature for 3 h, remove the pipette from the specimen, gently suck the residual ethanol on the surface of the specimen with filter paper, and dry it with a hair dryer on the cold wind setting, and then measure its optical density value.

[0068] (2) Detection method for the image retention rate; at 80 °C and a pressure of 1 kgf / cm 2 , use a thermal printer to heat the image for 1 second, (erased image color density value / original color density) * 100%.

[0069] (3) Detection of reversible erasable performance

[0070] The Zebra printer writes at a concentration of 30. By using a thermal printer at 140 °C and a pressure of 1 kgf / cm 2 , the image is heated and erased for 1 second, and the retention rate is less than 10%, indicating that the reversibility is successful once.

[0071] Table 1 Performance comparison of Example 1 and Comparative Examples 1 and 2

[0072]

[0073] In summary, through the structural design of the combination of the low-temperature color developer in the red thermal-sensitive coating and the high-temperature color developer in the black thermal-sensitive coating, the present invention realizes the color development temperature difference between different thermal-sensitive coatings and achieves color overlay; combined with an erasing aid, efficient erasing is realized.

[0074] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0075] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. Two-color thermal erasable paper designed based on color developer matching, characterized in that: The two-color thermosensitive erasable paper comprises a thermosensitive coating, wherein the thermosensitive coating comprises a red thermosensitive coating and a black thermosensitive coating arranged in sequence from top to bottom, and the color development temperature difference between the red thermosensitive coating and the black thermosensitive coating is greater than 30° C. The components of the red thermosensitive coating include a low-temperature color developer and an erasing aid I; The components of the black heat-sensitive coating include a high-temperature developer and an erasing aid II; The low-temperature developer includes at least one of PU-18 and PC-18; the erasing aid I includes at least one of ethylene glycol, polypropylene glycol, and stearamide; the structural formulas of PU-18 and PC-18 are as follows: ， ； The high temperature developer is at least one of the general formulas Ⅰ-Ⅱ, and the structure of the general formulas Ⅰ-Ⅱ is as follows: , in the general formula Ⅰ, r is 2 to 8, s is 12 to 30, , in the general formula II, r is 2 to 8, s is 12 to 30; The erasing aid II includes at least one of polyethylene glycol, polypropylene glycol, stearamide, OUN-18, and structural formula III, and the structural formula III is as follows: 。 2. The two-color thermal erasable paper based on the developer matching design according to claim 1, characterized in that: The mass percentage of the erasing aid I to the low-temperature developer is 30% to 50%; the mass percentage of the erasing aid II to the high-temperature developer is 20% to 50%.

3. The two-color thermal erasable paper based on the developer matching design according to claim 1, characterized in that: The high temperature developer is at least one of Formula I-1 and Formula II-1, and the structure of Formula I-1 is as follows: ; The structure of formula II-1 is as follows: .

4. The two-color thermal erasable paper based on the developer matching design according to claim 1, characterized in that: The red heat-sensitive coating comprises the following specific components in parts by weight: 30-50 parts of a low-temperature developer, 10-40 parts of an erasing aid I, 8-20 parts of a heat-sensitive dye, 40-60 parts of an adhesive resin and 20-40 parts of a filler.

5. The two-color thermal erasable paper based on the developer matching design according to claim 1, characterized in that: The black thermosensitive coating comprises the following specific components in parts by weight: 30-50 parts of high-temperature developer, 10-40 parts of erasing aid II, 8-20 parts of thermosensitive dye II, 40-60 parts of adhesive resin II and 20-40 parts of filler II.

6. The two-color thermal erasable paper based on the developer matching design according to claim 1, characterized in that: The two-color thermosensitive erasable paper further comprises a protective layer, a primer layer and a substrate, wherein the protective layer is disposed on the red thermosensitive coating layer, the primer layer is disposed under the black thermosensitive coating layer, and the primer layer is disposed on the substrate; The protective layer comprises the following specific components by weight: 3-10 parts of anti-ultraviolet additive, 5-10 parts of lubricant, and 80-90 parts of adhesive resin III; The primer layer comprises the following specific components in parts by weight: 80-90 parts of adhesive resin IV, 20-30 parts of thermal insulation filler, and 5-20 parts of brightener.

7. The two-color thermal erasable paper based on the developer matching design according to claim 6, characterized in that: The thickness of the protective layer is 3-4um, the thickness of the red thermosensitive coating is 2-3um, the thickness of the black thermosensitive coating is 2-3um, and the thickness of the primer coating is 1-3um.

8. A method for preparing a two-color thermal erasable paper based on a developer matching design according to any one of claims 1 to 7, characterized in that: The steps include: S1: preparing the components of the primer layer into a coating liquid, coating the coating liquid on a substrate, and drying to obtain a primer layer on the substrate; S2: preparing a coating liquid of a red thermosensitive coating from each component of the red thermosensitive coating; preparing a coating liquid of a black thermosensitive coating from each component of the black thermosensitive coating; applying the coating liquid of the red thermosensitive coating and the coating liquid of the black thermosensitive coating on the base coating in sequence, and drying to obtain a thermosensitive coating; S3: preparing the components of the protective layer into a coating liquid for the protective layer, coating the coating liquid on the heat-sensitive coating, and drying the coating liquid to obtain a protective layer; S4: The substrate, the base coating, the heat-sensitive coating and the protective layer are compounded by a hot pressing process to obtain a two-color heat-sensitive erasable paper designed based on a color developer combination.

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