Bisphenol-free thermosensitive coating composition as well as preparation method and application thereof

Abstract

The invention relates to a bisphenol-free thermosensitive coating composition as well as a preparation method and application thereof, and belongs to the technical field of thermosensitive coating compositions. The invention aims to solve the technical problems of poor color development stability and insufficient durability of a bisphenol-free coating in the prior art. The bisphenol-free thermosensitive coating composition is prepared from the following raw materials in percentage by mass: 8 to 10 percent of colorless dye, 17 to 20 percent of color developing agent, 8 to 10 percent of sensitizer, 35 to 42 percent of inorganic filler, 8 to 10 percent of water-soluble resin binder, 1 to 3 percent of antioxidant stabilizer, 6 to 7 percent of lubricant and 7 to 10 percent of scratch-resistant enhancer. The bisphenol-free thermosensitive coating composition provided by the invention is applied to thermosensitive paper, the developing definition, durability and surface hardness of the thermosensitive paper can be improved, the clearness and stability of handwriting under illumination and oil stain are improved, and the components are non-toxic, convenient to obtain, not easy to volatilize, free of bisphenol compounds, capable of meeting the environmental protection requirement, non-toxic, safe and suitable for industrial production. The environment-friendly property is good.

Description

Technical Field

[0001] The present application relates to the technical field of heat-sensitive coating compositions, and in particular to a bisphenol-free heat-sensitive coating composition and a preparation method and application thereof. Background Art

[0002] Thermal paper is a special paper widely used in the fields of ticket printing and label printing. Its core characteristic is that the thermal coating produces a color reaction through a thermal reaction, and the color changes after being heated. Traditional thermal coating materials often use ingredients containing bisphenol compounds (such as bisphenol A) as color developers or stabilizers for color development reactions. Although bisphenol compounds are widely used in thermal paper coatings, they have certain environmental pollution and potential hazards to human health. In particular, long-term exposure to bisphenol compounds may interfere with the endocrine system and affect the normal metabolism of organisms. With the improvement of people's environmental awareness and the increasing attention to health, the development of bisphenol-free, clear-colored and long-lasting thermal coating materials has become an inevitable trend in the development of thermal paper technology.

[0003] The demand for environmentally friendly, non-toxic thermal coating materials is increasing at home and abroad. Although there are many bisphenol-free thermal coatings in the prior art, they still have certain shortcomings in terms of color clarity and durability, especially in long-term use or in complex environments such as oil stains and light. The stability and color performance of bisphenol-free coatings are not as good as those of bisphenol-containing materials. Therefore, it is of great significance to develop a new type of bisphenol-free thermal coating composition that can ensure clear color and long-term durability, which has become a research hotspot in current technology. Summary of the invention

[0004] In view of this, the present application provides a bisphenol-free thermosensitive coating composition and a preparation method and application thereof. The bisphenol-free thermosensitive coating composition adopts innovative environmentally friendly materials and formulas, and has good environmental performance. By optimizing the ratio of each component and the preparation process of the composition, the goals of clear color, long-term durability and bisphenol-free are achieved, which can solve the problems of poor color stability and insufficient durability of bisphenol-free coatings in the prior art.

[0005] The first aspect of the present application provides a bisphenol-free thermosensitive coating composition, which includes the following raw materials in percentage by mass: 8-10% of colorless dye, 17-20% of developer, 8-10% of sensitizer, 35-42% of inorganic filler, 8-10% of water-soluble resin binder, 1-3% of antioxidant stabilizer, 6-7% of lubricant, and 7-10% of scratch resistance enhancer.

[0006] Preferably, the leuco dye is 2-phenylamino-3-methyl-6-dibutylaminofluoran (PDMA); or

[0007] The color developer is a bisphenol-free color developer, and the bisphenol-free color developer is p-hydroxybenzoic acid; or

[0008] The sensitizer is dixylylethane; or

[0009] The inorganic filler is a mixture of silicon dioxide and titanium dioxide, wherein the weight ratio of silicon dioxide to titanium dioxide is 1:(3-5), and the particle sizes of silicon dioxide and titanium dioxide are controlled within 50 μm; or

[0010] The water-soluble resin binder is polyvinyl alcohol; or

[0011] The antioxidant stabilizer is selected from one of 3-methyl-6-tert-butylphenol (Antioxidant 300), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ); or

[0012] The lubricant is selected from one of magnesium stearate, calcium stearate and zinc stearate; or

[0013] The scratch resistance enhancer is selected from at least one of nano silicon, nano aluminum oxide, and silicate nano particles.

[0014] Preferably, the thickness of the bisphenol-free thermosensitive coating is 5-15 μm.

[0015] The second aspect of the present application also provides a method for preparing the above-mentioned bisphenol-free thermosensitive coating composition, comprising the following steps:

[0016] (1) dissolving a water-soluble resin binder in water according to a certain proportion to prepare a solution, and dividing the solution into three equal parts, namely, a first solution, a second solution and a third solution;

[0017] (2) adding the colorless dye to the first solution in proportion, mixing and dispersing, and preparing a dye dispersion;

[0018] (3) adding the developer and the sensitizer to the second solution in proportion, mixing and dispersing, and preparing a developer dispersion;

[0019] (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer to the third solution in proportion, mixing and dispersing, and preparing a filler dispersion;

[0020] (5) The dye dispersion, the developer dispersion and the filler dispersion are mixed and dispersed to prepare a bisphenol-free heat-sensitive coating composition.

[0021] Preferably, in step (1), the water is deionized water, and the usage ratio of the water-soluble resin binder to the deionized water is (5-10 g):100 mL.

[0022] Preferably, in steps (2), (3) and (5), the mixing and dispersing time is 10 to 15 minutes; or

[0023] In step (4), the mixing and dispersing time is 30 to 45 minutes.

[0024] Preferably, in steps (2), (3), (4) and (5), the mixing and dispersing is performed by shearing and dispersing using a high-speed shearing machine. Compared with dispersion methods such as grinding, the shearing and dispersing efficiency of a high-speed shearing machine can be greatly improved, and the raw materials do not agglomerate and are dispersed evenly.

[0025] The third aspect of the present application also provides a use of the above-mentioned bisphenol-free thermal-sensitive coating composition in thermal paper.

[0026] Preferably, it consists of the following steps:

[0027] The bisphenol-free thermal-sensitive coating composition is uniformly coated on the surface of a paper base, and then a hot air drying device is used to dry and solidify the paper base coated with the bisphenol-free thermal-sensitive coating composition to obtain thermal paper.

[0028] Preferably, the specific process of coating is: using a multi-layer coating technology and using a precision coating machine to complete the coating process; or

[0029] The drying temperature is 120-160°C.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] 1. The bisphenol-free thermal coating composition of the present application adopts the environmentally friendly thermal pigment p-hydroxybenzoic acid as the bisphenol-free color developer, and adds dixylene ethane as a sensitizer. When applied to thermal paper, it can make the thermal paper produce a significant and clear color change after heating, meeting the needs of high-quality thermal printing, and after color development, it is waterproof and grease-resistant, and has high continuous durability.

[0032] 2. The bisphenol-free thermal-sensitive coating composition of the present application is added with an antioxidant stabilizer, a lubricant and nano-hard particles as a scratch-resistant enhancer. When applied to thermal paper, it can effectively improve the surface mechanical properties of the thermal paper and maintain the glossiness, thereby significantly improving the durability and long-term stability of the thermal paper.

[0033] 3. The bisphenol-free thermal coating composition of the present application is applied to thermal paper, which can improve the color clarity, durability, and surface hardness of the thermal paper, and improve the clarity and stability of the handwriting under light and oil stains. The components are non-toxic and easy to obtain, the ingredients are not easy to volatilize and do not contain bisphenol compounds, which meets environmental protection requirements, is non-toxic and safe, and has good environmental protection properties. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of this application clearer, the technical solution in this application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the application. The technology and method known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and method should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0036] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0037] In the following examples and comparative examples, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods; unless otherwise specified, the raw materials of the examples of the present application are all commercially available, and the purity of each chemical component is above 99%.

[0038] Example 1

[0039] The preparation method of the bisphenol-free heat-sensitive coating composition in this embodiment comprises the following steps:

[0040] (1) dissolving the polyvinyl alcohol in a prescribed amount in 10 times deionized water to prepare a solution, and then dividing the solution into three equal parts, namely, a first part of a polyvinyl alcohol aqueous solution, a second part of a polyvinyl alcohol aqueous solution, and a third part of a polyvinyl alcohol aqueous solution;

[0041] (2) adding the colorless dye to the first portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 15 minutes using a high-speed shearing machine to prepare a dye dispersion;

[0042] (3) Adding the developer and sensitizer to the second portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 10 minutes using a high-speed shearing machine to prepare a developer dispersion;

[0043] (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer into the third portion of the polyvinyl alcohol aqueous solution according to the ratio, and mixing and dispersing the mixture using a high-speed shearing machine for 30 minutes to prepare a filler dispersion;

[0044] (5) mixing the above-mentioned dye dispersion, developer dispersion and filler dispersion, and mixing and dispersing them for 15 minutes using a high-speed shearing machine to prepare a bisphenol-free heat-sensitive coating composition;

[0045] (6) using a multi-layer coating technique and a precision coating machine to uniformly coat the bisphenol-free heat-sensitive coating composition on the surface of the paper base;

[0046] (7) The paper base coated with the bisphenol-free thermal-sensitive coating composition was dried and cured at 150° C. using a hot air drying device to obtain thermal paper.

[0047] Example 2

[0048] The preparation method of the bisphenol-free heat-sensitive coating composition in this embodiment comprises the following steps:

[0049] (1) dissolving the polyvinyl alcohol in a prescribed amount in 10 times deionized water to prepare a solution, and then dividing the solution into three equal parts, namely, a first part of a polyvinyl alcohol aqueous solution, a second part of a polyvinyl alcohol aqueous solution, and a third part of a polyvinyl alcohol aqueous solution;

[0050] (2) adding the colorless dye to the first portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 10 minutes using a high-speed shearing machine to prepare a dye dispersion;

[0051] (3) Adding the developer and sensitizer to the second portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 10 minutes using a high-speed shearing machine to prepare a developer dispersion;

[0052] (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer into the third portion of the polyvinyl alcohol aqueous solution according to the ratio, and mixing and dispersing the mixture using a high-speed shearing machine for 30 minutes to prepare a filler dispersion;

[0053] (5) mixing the above-mentioned dye dispersion, developer dispersion and filler dispersion, and mixing and dispersing them for 15 minutes using a high-speed shearing machine to prepare a bisphenol-free heat-sensitive coating composition;

[0054] (6) using a multi-layer coating technique and a precision coating machine to uniformly coat the bisphenol-free heat-sensitive coating composition on the surface of the paper base;

[0055] (7) The paper base coated with the bisphenol-free thermal-sensitive coating composition was dried and cured at 150° C. using a hot air drying device to obtain thermal paper.

[0056] Example 3

[0057] The preparation method of the bisphenol-free heat-sensitive coating composition in this embodiment comprises the following steps:

[0058] (1) dissolving the polyvinyl alcohol in a prescribed amount in 10 times deionized water to prepare a solution, and then dividing the solution into three equal parts, namely, a first part of a polyvinyl alcohol aqueous solution, a second part of a polyvinyl alcohol aqueous solution, and a third part of a polyvinyl alcohol aqueous solution;

[0059] (2) adding the colorless dye to the first portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 10 minutes using a high-speed shearing machine to prepare a dye dispersion;

[0060] (3) Adding the developer and sensitizer to the second portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 15 minutes using a high-speed shearing machine to prepare a developer dispersion;

[0061] (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer into the third portion of the polyvinyl alcohol aqueous solution according to the ratio, and mixing and dispersing the mixture using a high-speed shearing machine for 30 minutes to prepare a filler dispersion;

[0062] (5) mixing the above-mentioned dye dispersion, developer dispersion and filler dispersion, and mixing and dispersing them for 15 minutes using a high-speed shearing machine to prepare a bisphenol-free heat-sensitive coating composition;

[0063] (6) using a multi-layer coating technique and a precision coating machine to uniformly coat the bisphenol-free heat-sensitive coating composition on the surface of the paper base;

[0064] (7) The paper base coated with the bisphenol-free thermal-sensitive coating composition was dried and cured at 150° C. using a hot air drying device to obtain thermal paper.

[0065] Example 4

[0066] The preparation method of the bisphenol-free heat-sensitive coating composition in this embodiment comprises the following steps:

[0067] (1) dissolving the polyvinyl alcohol in a prescribed amount in 10 times deionized water to prepare a solution, and then dividing the solution into three equal parts, namely, a first part of a polyvinyl alcohol aqueous solution, a second part of a polyvinyl alcohol aqueous solution, and a third part of a polyvinyl alcohol aqueous solution;

[0068] (2) adding the colorless dye to the first portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 15 minutes using a high-speed shearing machine to prepare a dye dispersion;

[0069] (3) Adding the developer and sensitizer to the second portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 15 minutes using a high-speed shearing machine to prepare a developer dispersion;

[0070] (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer into the third portion of the polyvinyl alcohol aqueous solution according to the ratio, and mixing and dispersing the mixture using a high-speed shearing machine for 30 minutes to prepare a filler dispersion;

[0071] (5) mixing the above-mentioned dye dispersion, developer dispersion and filler dispersion, and mixing and dispersing them for 15 minutes using a high-speed shearing machine to prepare a bisphenol-free heat-sensitive coating composition;

[0072] (6) using a multi-layer coating technique and a precision coating machine to uniformly coat the bisphenol-free heat-sensitive coating composition on the surface of the paper base;

[0073] (7) The paper base coated with the bisphenol-free thermal-sensitive coating composition was dried and cured at 150° C. using a hot air drying device to obtain thermal paper.

[0074] Example 5

[0075] The preparation method of the bisphenol-free heat-sensitive coating composition in this embodiment comprises the following steps:

[0076] (1) dissolving the polyvinyl alcohol in a prescribed amount in 10 times deionized water to prepare a solution, and then dividing the solution into three equal parts, namely, a first part of a polyvinyl alcohol aqueous solution, a second part of a polyvinyl alcohol aqueous solution, and a third part of a polyvinyl alcohol aqueous solution;

[0077] (2) adding the colorless dye to the first portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 15 minutes using a high-speed shearing machine to prepare a dye dispersion;

[0078] (3) Adding the developer and sensitizer to the second portion of the polyvinyl alcohol aqueous solution according to the ratio, mixing and dispersing for 15 minutes using a high-speed shearing machine to prepare a developer dispersion;

[0079] (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer into the third portion of the polyvinyl alcohol aqueous solution according to the proportion, mixing and dispersing the mixture using a high-speed shearing machine for 40 minutes to prepare a filler dispersion;

[0080] (5) mixing the above-mentioned dye dispersion, developer dispersion and filler dispersion, and mixing and dispersing them for 15 minutes using a high-speed shearing machine to prepare a bisphenol-free heat-sensitive coating composition;

[0081] (6) using a multi-layer coating technique and a precision coating machine to uniformly coat the bisphenol-free heat-sensitive coating composition on the surface of the paper base;

[0082] (7) The paper base coated with the bisphenol-free thermal-sensitive coating composition was dried and cured at 150° C. using a hot air drying device to obtain thermal paper.

[0083] Comparative Example 1

[0084] In the method for preparing the thermal coating composition and thermal paper provided in this comparative example, no sensitizer is added in step (3), and the rest is consistent with Example 5.

[0085] Comparative Example 2

[0086] In the method for preparing the thermal coating composition and thermal paper provided in this comparative example, no scratch resistance enhancer is added in step (4), and the rest is consistent with Example 5.

[0087] The following is the bisphenol-free thermosensitive coating composition of Examples 1 to 5 of the present application and Comparative Examples 1 to 2: wherein the colorless dye is PDMA, the developer is p-hydroxybenzoic acid, the sensitizer is dixylene ethane, the inorganic filler is a mixture of 50 μm-diameter silicon dioxide and titanium dioxide, the water-soluble resin binder is polyvinyl alcohol, the antioxidant stabilizer is antioxidant 300, the lubricant is magnesium stearate, and the scratch resistance enhancer is aluminum oxide micropowder. The specific weight ratio is shown in Table 1.

[0088] Table 1 Proportion table of Examples 1 to 5 and Comparative Examples 1 to 2

[0089]

[0090] Test example

[0091] A thermal printer was used to print a two-dimensional code on the thermal paper prepared in Examples 1 to 5 of the present application and Comparative Examples 1 to 2, and the Deli double-layer thermal label paper. A decoder was used to detect the resolution, and the color development time was detected by observation. Edible oil was applied to the surface of the color-developing thermal paper for 48 hours, and the color development effect was observed. The stability under light was tested, and a xenon lamp was used to irradiate the printed thermal paper. The power of the xenon lamp was controlled to 1800 W, and the color development effect was observed after continuous irradiation at room temperature for 48 hours. The scratch resistance hardness was tested using the GB / T6739-2006 standard.

[0092] Deli double-layer thermal label paper was used as comparative example 3 of this application, and the specific test results are shown in Table 2.

[0093] Table 2 Test results of Examples 1 to 5 and Comparative Examples 1 to 3

[0094]

[0095] From the data comparison in Table 2, it can be seen that after the bisphenol-free thermal coating composition of the present application uses p-hydroxybenzoic acid instead of bisphenol compounds as a color developer, the color resolution of the thermal paper is improved when it is applied to the thermal paper, and the effect is better when used with the sensitizer dixylene ethane, and the color development time, light resistance, and oil resistance are better than those of bisphenol thermal paper. After adding aluminum oxide powder to the bisphenol-free thermal coating composition, it plays a protective role, and the application in the thermal paper further improves the color development duration and stability of the thermal paper, especially the surface strength is greatly improved, which can better improve the service life of the thermal paper.

[0096] In summary, the bisphenol-free thermal coating composition provided in the present application, after being applied to thermal paper, enables the thermal paper to have excellent color clarity, color stability, surface strength and environmental protection characteristics, can meet the needs of various usage scenarios, and provides a new idea for the sustainable development of the thermal paper industry; and the preparation method of the present application is convenient and reliable, the raw materials are environmentally friendly and healthy, and have good safety. It is applied to thermal paper with good imaging effect and more durable use, and has high application value.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A bisphenol-free heat-sensitive coating composition, characterized in that: The bisphenol-free thermosensitive coating composition comprises the following raw materials in percentage by mass: 8-10% of colorless dye, 17-20% of developer, 8-10% of sensitizer, 35-42% of inorganic filler, 8-10% of water-soluble resin binder, 1-3% of antioxidant stabilizer, 6-7% of lubricant, and 7-10% of scratch resistance enhancer.

2. The bisphenol-free heat-sensitive coating composition according to claim 1, characterized in that: The colorless dye is 2-phenylamino-3-methyl-6-dibutylaminofluoran; or The color developer is a bisphenol-free color developer, and the bisphenol-free color developer is p-hydroxybenzoic acid; or The sensitizer is dixylylethane; or The inorganic filler is a mixture of silicon dioxide and titanium dioxide, wherein the weight ratio of silicon dioxide to titanium dioxide is 1:(3-5), and the particle sizes of silicon dioxide and titanium dioxide are controlled within 50 μm; or The water-soluble resin binder is polyvinyl alcohol; or The antioxidant stabilizer is selected from one of 3-methyl-6-tert-butylphenol, butylated hydroxyanisole, butylated hydroxytoluene and tert-butylhydroquinone; or The lubricant is selected from one of magnesium stearate, calcium stearate and zinc stearate; or The scratch resistance enhancer is selected from at least one of nano silicon, nano aluminum oxide, and silicate nano particles.

3. The bisphenol-free heat-sensitive coating composition according to claim 1, characterized in that: The thickness of the bisphenol-free heat-sensitive coating is 5-15 μm.

4. A method for preparing the bisphenol-free heat-sensitive coating composition according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) dissolving a water-soluble resin binder in water according to a certain proportion to prepare a solution, and dividing the solution into three equal parts, namely, a first solution, a second solution and a third solution; (2) adding the colorless dye to the first solution in proportion, mixing and dispersing, and preparing a dye dispersion; (3) adding the developer and the sensitizer to the second solution in proportion, mixing and dispersing, and preparing a developer dispersion; (4) adding an inorganic filler, an antioxidant stabilizer, a lubricant and a scratch resistance enhancer to the third solution in proportion, mixing and dispersing, and preparing a filler dispersion; (5) The dye dispersion, the developer dispersion and the filler dispersion are mixed and dispersed to prepare a bisphenol-free heat-sensitive coating composition.

5. The method for preparing the bisphenol-free heat-sensitive coating composition according to claim 4, characterized in that: In step (1), the water is deionized water, and the usage ratio of the water-soluble resin binder to the deionized water is (5-10 g):100 mL.

6. The method for preparing the bisphenol-free heat-sensitive coating composition according to claim 4, characterized in that: In steps (2), (3) and (5), the mixing and dispersing time is 10 to 15 minutes; or In step (4), the mixing and dispersing time is 30 to 45 minutes.

7. The method for preparing the bisphenol-free heat-sensitive coating composition according to claim 4, characterized in that: In steps (2), (3), (4) and (5), the mixing and dispersing is performed by shearing and dispersing using a high-speed shearing machine.

8. Use of the bisphenol-free thermal-sensitive coating composition according to any one of claims 1 to 3 in thermal paper.

9. Use of the bisphenol-free thermal-sensitive coating composition in thermal paper according to claim 8, characterized in that: It consists of the following steps: The bisphenol-free thermal-sensitive coating composition is uniformly coated on the surface of a paper base, and then a hot air drying device is used to dry and solidify the paper base coated with the bisphenol-free thermal-sensitive coating composition to obtain thermal paper.

10. Use of the bisphenol-free thermal-sensitive coating composition in thermal paper according to claim 9, characterized in that: The specific process of the coating is: using a multi-layer coating technology and using a precision coating machine to complete the coating process; or The drying temperature is 120-160°C.

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