Waterproof heat-insulating coating for thermo-sensitive paper and preparation method of waterproof heat-insulating coating

Abstract

The invention discloses a waterproof and heat-insulating coating for thermo-sensitive paper and a preparation method of the waterproof and heat-insulating coating, and relates to the technical field of waterproof and heat-insulating coatings. Comprising 35%-55% of a wax component, 5%-10% of a surfactant, 30%-45% of an aqueous solvent, 5%-15% of nano silicon dioxide, 0.5%-2% of a stabilizer, 0.5%-1.5% of a pH regulator and 0.5%-1.5% of an anti-ultraviolet agent. The invention further provides a preparation method of the waterproof heat-insulating coating for the thermo-sensitive paper. After the coating material is applied to the thermo-sensitive paper, the surface characteristics of the thermo-sensitive paper can be improved, the water resistance and the heat insulation property of the paper are improved, and the color development is clear, stable and long in lasting time in illumination, blister and oil stain environments.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal paper, and specifically relates to a waterproof and heat-insulating coating for thermal paper and a preparation method thereof. Background Art

[0002] Thermal paper is widely used in the fields of bill printing, label printing, receipt printing, etc. of fax machines, printers, cash registers, etc. The surface coating makes graphic and text information remain on the paper through a thermal reaction. The working principle of thermal paper depends on the thermal reaction of the surface coating, so the surface of thermal paper must maintain a certain degree of cleanliness and integrity. With the wide use of thermal paper, when exposed to high-temperature and humid environments, problems such as coating fading, failure, and even paper aging often occur, affecting the printing quality and use effect.

[0003] Currently, the thermal paper on the market can generally only be used in relatively dry environments. Although the existing thermal paper coatings can provide certain water resistance, their tolerance to temperature and humidity changes is poor.

[0004] In order to address this problem, in recent years, some researchers have tried to improve the heat insulation and waterproof performance of thermal paper by improving the coating of thermal paper or using special coatings. However, the existing technical solutions often face problems such as high cost, complex preparation, and unstable performance. Therefore, how to design a simple, low-cost coating for thermal paper with good heat insulation and waterproof effects has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a waterproof and heat-insulating coating for thermal paper and a preparation method thereof. This coating can solve the problems of poor color display stability and insufficient durability in the existing technology under high-temperature and humid environments. The waterproof and heat-insulating coating material of the present invention adopts innovative environmental protection materials and formulations, and realizes the goal of clear color display and long-term durability in harsh environments by optimizing the ratio of each component and the preparation process.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A waterproof and heat-insulating coating for thermal paper, by weight, includes: 35%-55% of wax component, 5%-10% of surfactant, 30%-45% of aqueous solvent, 5%-15% of nano-silica, 0.5%-2% of stabilizer, 0.5%-1.5% of pH regulator, 0.5%-1.5% of ultraviolet inhibitor waterproof and heat-insulating coating material.

[0007] Preferably, the wax component uses microcrystalline wax and polyethylene wax, and is mixed according to a weight ratio of 1:2.

[0008] Preferably, the surfactant uses one or several mixtures of sodium dodecyl sulfate, polyethylene glycol ether, and polyethers.

[0009] Preferably, the stabilizer is one or a mixture of sodium polyacrylate, sodium alginate, antioxidant 300, BHA, BHT and TBHQ.

[0010] Preferably, the pH adjuster is acetic acid, citric acid or a mixture thereof.

[0011] Preferably, the aqueous solvent is deionized water or ethylene glycol or a mixture thereof.

[0012] Preferably, the UV protection agent is titanium dioxide, zinc oxide particles or a mixture thereof.

[0013] Preferably, the particle size of the titanium dioxide and zinc oxide particles is controlled within 100 nm.

[0014] A method for preparing a waterproof and heat-insulating coating comprises the following steps: (1) heating a formulated wax component to a molten state at a heating temperature of 90-120° C.;

[0015] (2) slowly adding the melted wax liquid into an aqueous solvent, into which a surfactant has been pre-added, stirring and dispersing the wax liquid to prepare an emulsion, with the stirring time being 20 min to 30 min;

[0016] (3) gradually adding nano-silicon dioxide, stabilizer, pH adjuster and UV inhibitor to the emulsion, and continuing to stir and mix, with the mixing and dispersion time being 30 min to 60 min until uniform;

[0017] (4) The stirred solution is heated for a short time at 60-70°C for 10-15 min to help the components react fully and further improve the stability of the coating.

[0018] A thermal paper, wherein a prepared coating is evenly coated on the surface of the thermal paper, the coating thickness is controlled at 5-10 μm, and after coating, it is dried at 40-60° C., the drying time is controlled at 30-60 minutes to ensure that the coating is completely cured.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The waterproof and heat-insulating coating material for thermal paper of the present invention adopts wax emulsion to improve the surface properties of paper, can provide better waterproofness, provide protection for colored writing or patterns in a humid, oily or water-immersed environment, and improve the waterproof and grease-resistant properties of thermal paper.

[0021] 2. The nano-silicon dioxide added to the coating of the present invention can form a tiny thermal isolation layer, effectively reducing the conduction of heat, providing a heat insulation effect, and ensuring the color development effect of the thermal paper in a high temperature environment.

[0022] 3. The waterproof and heat-insulating coating material of the present invention significantly improves the durability and long-term stability of the color development of thermal paper in harsh environments, meeting the high-quality thermal printing requirements in different environments. The selected components are all non-toxic and easily obtainable, meeting the environmental protection requirements, being non-toxic and safe. Specific Embodiments

[0023] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0024] Unless otherwise specified, the raw materials of this application are all commercially available, and the purity of each chemical component is above 99%.

[0025] The following are the compositions of the coating materials of Examples 1-7 of this application. The surfactant is selected as polyethylene glycol ether, the aqueous solvent is selected as deionized water, the stabilizer is selected as a mixture of sodium polyacrylate and BHT, the pH regulator is selected as acetic acid, and the ultraviolet light inhibitor is selected as titanium dioxide. The specific weight ratios are shown in Table 1.

[0026] Table 1 Ratio Table of Examples 1-7

[0027]

[0028] Example 1

[0029] A preparation method of a waterproof and heat-insulating coating for thermal paper is as follows:

[0030] (1) Heat the wax component in the formula amount to 90 °C until it reaches the molten state;

[0031] (2) Slowly add the molten wax liquid to the aqueous solvent, and the surfactant is pre-added to the aqueous solvent, and stir and disperse for 20 min to prepare an emulsion;

[0032] (3) Gradually add nano-silica, stabilizer, pH regulator, and ultraviolet light inhibitor to the emulsion, and use a high-speed shear mixer for dispersion, and the mixing and dispersion time is 30 min;

[0033] (4) Heat the stirred solution to 60 °C and keep it warm for 10 min to help the components react fully and improve the stability of the coating.

[0034] Example 2

[0035] A preparation method of a waterproof and heat-insulating coating for thermal paper is as follows:

[0036] (1) Heat the wax component in the formula amount to 100 °C until it reaches the molten state;

[0037] (2) Slowly add the molten wax liquid to the aqueous solvent, in which a surfactant has been pre-added, and stir and disperse for 25 min to prepare an emulsion;

[0038] (3) Gradually add nano-silica, stabilizer, pH regulator, and ultraviolet inhibitor to the emulsion, and use a high-speed shear mixer to disperse, with a mixing and dispersion time of 30 min;

[0039] (4) Heat the stirred solution to 60 °C and keep it warm for 10 min to help the components react fully and improve the stability of the coating.

[0040] Example 3

[0041] A preparation method of a waterproof and heat-insulating coating for thermal paper is as follows:

[0042] (1) Heat the wax component in the formula amount to 100 °C until it reaches the molten state;

[0043] (2) Slowly add the molten wax liquid to the aqueous solvent, in which a surfactant has been pre-added, and stir and disperse for 25 min to prepare an emulsion;

[0044] (3) Gradually add nano-silica, stabilizer, pH regulator, and ultraviolet inhibitor to the emulsion, and use a high-speed shear mixer to disperse, with a mixing and dispersion time of 40 min;

[0045] (4) Heat the stirred solution to 60 °C and keep it warm for 15 min to help the components react fully and improve the stability of the coating.

[0046] Example 4

[0047] A preparation method of a waterproof and heat-insulating coating for thermal paper is as follows:

[0048] (1) Heat the wax component in the formula amount to 110 °C until it reaches the molten state;

[0049] (2) Slowly add the molten wax liquid to the aqueous solvent, in which a surfactant has been pre-added, and stir and disperse for 30 min to prepare an emulsion;

[0050] (3) Gradually add nano-silica, stabilizer, pH regulator, and ultraviolet inhibitor to the emulsion, and use a high-speed shear mixer to disperse, with a mixing and dispersion time of 40 min;

[0051] (4) Heat the stirred solution to 70 °C and keep it warm for 20 min to help the components react fully and improve the stability of the coating.

[0052] Example 5

[0053] A method for preparing a waterproof and heat-insulating coating for thermal paper is as follows:

[0054] (1) Heat the wax component in the formula amount to 110 °C until it reaches the molten state;

[0055] (2) Slowly add the molten wax liquid to the aqueous solvent in which a surfactant has been previously added, and stir and disperse for 30 min to prepare an emulsion;

[0056] (3) Gradually add nano-silica, stabilizer, pH regulator, and ultraviolet light inhibitor to the emulsion, and use a high-speed shear mixer for dispersion. The mixing and dispersion time is 60 min;

[0057] (4) Heat the stirred solution to 70 °C and keep it warm for 20 min to help the components react fully and improve the stability of the coating.

[0058] Example 6 and Example 7 respectively use a single wax component, and the other preparation steps are the same as those described in Example 3.

[0059] Use the commercially purchased double-layer thermal label paper as the comparative example of this application. The specific test results are shown in Table 2.

[0060] Table 2 Test results of Examples 1-5 and the comparative example

[0061]

[0062] Use a thermal printer to print QR codes on the thermal paper prepared in Examples 1-5 of this application, use a decoder to detect the resolution, and observe the color development duration through detection; soak the thermal paper after color development in water for 12 h and then observe the color preservation rate; apply edible oil on the surface of the color-developed thermal paper for 24 h and then observe the color development effect; test its stability under light. Use a xenon lamp to irradiate the printed thermal paper, control the power of the xenon lamp to 1800 W, and observe the color development effect after continuous irradiation at room temperature for 24 h; detect the scratch resistance hardness using the GB / T6739-2006 standard.

[0063] It can be seen from the data comparison in Table 2 that after applying the coating material of this application, the resolution clarity of the color development of the thermal paper is further improved, the water immersion preservation rate, oil resistance, and stability under light of the thermal paper with clear color development are improved, and the surface strength is also greatly improved. And the effect of using the two wax components of microcrystalline wax and polyethylene wax in combination is better than that of using a single one.

[0064] The present invention provides a waterproof and heat-insulating coating for thermal paper. After being applied to thermal paper, it enables the thermal paper to have excellent color display stability and durability under water immersion, oil stains, high temperature and light, can meet the requirements of various usage scenarios, and provides new ideas for the sustainable development of the thermal paper industry. The preparation method is convenient and reliable, the raw materials are environmentally friendly, healthy, safe, have good imaging effects and are more durable in use, and have high application value.

[0065] As is known by technical common sense, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A waterproof and heat-insulating coating for thermal paper, characterized in that: The ingredients are calculated by weight and include: 35%-55% wax component, 5%-10% surfactant, 30%-45% aqueous solvent, 5%-15% nano silicon dioxide, 0.5%-2% stabilizer, 0.5%-1.5% pH adjuster, 0.5%-1.5% UV protection agent, and waterproof and heat-insulating coating material.

2. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The wax component is microcrystalline wax and polyethylene wax, which are mixed in a weight ratio of 1:

2.

3. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The surfactant is one or a mixture of sodium lauryl sulfate, polyethylene glycol ether, and polyether.

4. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The stabilizer is one or a mixture of sodium polyacrylate, sodium alginate, antioxidant 300, BHA, BHT and TBHQ.

5. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The pH adjuster is acetic acid, citric acid or a mixture thereof.

6. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The aqueous solvent is deionized water or ethylene glycol or a mixture thereof.

7. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The anti-ultraviolet agent is titanium dioxide, zinc oxide particles or a mixture thereof.

8. The waterproof and heat-insulating coating for thermal paper according to claim 1, characterized in that: The particle sizes of the titanium dioxide and zinc oxide particles are controlled within 100 nm.

9. A method for preparing the waterproof and heat-insulating coating for thermal paper according to claims 1-8, characterized in that: The method comprises the following steps: (1) heating a formulated amount of wax component to a molten state at a heating temperature of 90-120° C.; (2) slowly adding the melted wax liquid into an aqueous solvent, into which a surfactant has been pre-added, stirring and dispersing the wax liquid to prepare an emulsion, with the stirring time being 20 min to 30 min; (3) gradually adding nano-silicon dioxide, stabilizer, pH adjuster and UV inhibitor to the emulsion, and continuing to stir and mix, with the mixing and dispersion time being 30 min to 60 min until uniform; (4) The stirred solution is heated for a short time at 60-70°C for 10-15 min to help the components react fully and further improve the stability of the coating.

10. The thermal paper prepared by using the waterproof and heat-insulating coating according to claims 1-8, characterized in that: The prepared coating is evenly coated on the surface of the thermal paper, and the coating thickness is controlled at 5-10μm. After coating, it is dried at 40-60℃, and the drying time is controlled at 30-60 minutes to ensure that the coating is completely cured.

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