Thermal transfer ribbon for lamp box fabric

Abstract

The thermal transfer ribbon comprises a base material layer, a color layer and a back coating layer, the color layer is arranged on one side face of the base material layer, and the back coating layer is arranged on the other side face of the base material layer; the color layer comprises the following components: a methacrylic acid copolymer A, a methacrylic acid copolymer B, vinyl chloride-vinyl acetate resin, a pigment, wax and a first filler. The lamp box cloth printed by the thermal transfer ribbon for the lamp box cloth is uniform in hue, bright in color and fine and smooth in picture, and the surface of the lamp box is smooth, seamless and not prone to wrinkling. The thermal transfer ribbon structure is mainly composed of the back coating layer and the front color layer, pattern manufacturing can be achieved in a digital printing mode, film pasting is not needed, cost is low, and efficiency is high. By strictly controlling a pigment dispersion process and adding a specific filler or an auxiliary agent to carry out matte treatment on the thermal transfer ribbon, the thermal transfer ribbon has higher weather resistance and certain light transmission, and has the same display effect in the daytime and at night.

Description

Technical Field

[0001] The invention relates to the technical field related to thermal transfer carbon ribbons, and in particular to a thermal transfer carbon ribbon for light box cloth. Background Art

[0002] At present, most of the colorful patterns and texts on advertising light boxes are realized by pasting films on the light box cloth. However, its production and installation costs are relatively high, making it less suitable for some occasions with limited budgets. By preparing a carbon ribbon that can be thermally transferred on the light box cloth, it is also a feasible solution for making light boxes to print various required patterns on the light box cloth printing substrate. Summary of the invention

[0003] In order to solve one or more technical problems existing in the prior art, the present invention provides a thermal transfer carbon ribbon for light box cloth.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: A thermal transfer carbon ribbon for a light box cloth comprises a substrate layer, a color layer and a back coating layer, wherein the color layer is arranged on one side of the substrate layer, and the back coating layer is arranged on the other side of the substrate layer;

[0005] The components of the color layer include methacrylic acid copolymer A, methacrylic acid copolymer B, chloroacetic acid resin, pigment, wax and a first filler.

[0006] The beneficial effects of the present invention are as follows: the light box cloth printed with the thermal transfer carbon ribbon of the present invention has uniform tone, bright colors, delicate pictures, and the surface of the light box is smooth and seamless, and not easy to wrinkle. The carbon ribbon structure is mainly composed of a back coating and a front color layer, and the pattern can be produced by digital printing without film pasting, with low cost and high efficiency. By strictly controlling the pigment dispersion process and adding specific fillers or additives to matte the carbon ribbon, it has high weather resistance and certain light transmittance, which does not affect the use of the light box at night, so that it has the same display effect during the day and at night.

[0007] Among them, the wax can be selected from microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylenes, candelilla wax, polyester wax, partially modified wax, fatty acid esters and fatty acid amides, etc., preferably polyethylene wax; the content of the wax in the color layer is 0.5%-5%, preferably 2%-4%, and the wax can provide good smoothness of the pattern after printing and improve the friction resistance of the pattern. When the content is low, it cannot provide sufficient smoothness and the friction resistance of the pattern decreases. When the content is too high, it affects its adhesion to the light box cloth printing substrate; directly adding wax powder to the color layer instead of selecting a wax system release layer can ensure that the main component of the pattern surface after printing is resin, and the pattern layer can be used as a good printing coating for subsequent color printing to ensure that the pattern formed after multi-color printing has good adhesion and transfer integrity.

[0008] The filler can be ultrafine silica, talc, kaolin, etc., preferably ultrafine silica; the content of the filler in the color layer is 3%-10%, preferably 3%-5%. The filler can effectively reduce glare, make the reflection of light on the surface of the film more uniform and soft, reduce bright spots or dark areas caused by concentrated reflection of light, help maintain color uniformity in reflection and projection environments, and allow viewers to experience consistent color performance from different angles.

[0009] The resin carbon ribbon of the present invention has a simple structure, is free of auxiliary coatings such as various adhesive layers and release layers, and has good economic efficiency.

[0010] Based on the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the molecular weight of the methacrylic acid copolymer A is greater than 80,000, and the glass transition temperature Tg is greater than 90°C; the molecular weight of the methacrylic acid copolymer B is less than 40,000, and the glass transition temperature Tg is less than 100°C; the vinyl chloride content in the chlorovinyl resin is greater than 85%, and the degree of polymerization K is greater than 15.

[0012] The beneficial effect of adopting the above further scheme is: using two methacrylic acid copolymers, one with a high molecular weight greater than 80,000, can give the printed pattern good light resistance and weather resistance, and at the same time, the methacrylic acid copolymer has a good waterproof effect, which can further improve the life and effect of the printed pattern in outdoor use. The other uses a smaller molecular weight of less than 40,000, has good light transmittance and good peeling transfer, which can ensure that the carbon ribbon has good transfer ability. Vinyl chloride resin has excellent pigment dispersibility and film-forming properties, which provides good help for the coating and film formation of the carbon ribbon. At the same time, it has good adhesion to the substrate PET, ensuring the good foil retention of the carbon ribbon ink. The high polar groups it contains provide help for the good transfer adaptability of the carbon ribbon on various substrates.

[0013] Furthermore, the molecular weight of the methacrylic acid copolymer A is greater than 110,000, and the glass transition temperature Tg is greater than 100°C; the molecular weight of the methacrylic acid copolymer B is less than 10,000, and the glass transition temperature Tg is less than 80°C.

[0014] Furthermore, the pigment is an organic pigment, and the particle size D50 of the pigment in the color layer is less than 0.1, and D100 is less than 0.3.

[0015] The beneficial effect of adopting the above further scheme is that the pigment can be selected from yellow (such as PY150, PY110, PY83, PY139, PY192, PY13, etc.), red (such as PR149, PR254, PR264, PR177, PR122, etc.), blue (phthalocyanine blue 15:0, phthalocyanine blue 15:1, phthalocyanine blue 15:2, phthalocyanine blue 15:3, phthalocyanine blue 15:4 and phthalocyanine blue 15:6), green (phthalocyanine green 7 and phthalocyanine green 34), purple (pigment violet 19, pigment violet 23, etc.), black (carbon black), etc. The pigment is subsequently ground to control its particle size D50 < 0.1 and D100 < 0.3, so that it can be evenly distributed in the coating so that under the action of light, the absorption and reflection of light of different wavelengths are relatively consistent, and the entire film surface presents a uniform color effect, avoiding color differences caused by pigment agglomeration or uneven distribution. This type of pigment has good light transmittance, light resistance and weather resistance, which can improve the color effect during thermal transfer and the reliability of outdoor use.

[0016] Furthermore, in terms of weight percentage, the methacrylic acid copolymer accounts for 30% to 50% of the color layer, the acrylic acid copolymer accounts for 3% to 10% of the color layer, the chlorovinyl resin accounts for 8% to 15% of the color layer, the pigment accounts for 30% to 50% of the color layer, the wax accounts for 0.5% to 5% of the color layer, and the first filler accounts for 3% to 10% of the color layer.

[0017] Furthermore, the preparation method of the color layer is as follows: methacrylic acid copolymer A, methacrylic acid copolymer B, chloroacetic resin, pigment, wax and filler are dissolved and ground to prepare a color layer coating liquid, so that the pigment particle size D50 in the color layer coating liquid is less than 0.1 and D100 is less than 0.3, and the color layer is coated on the substrate layer by a 300-340-line ceramic anilox roller and a gravure coater, and dried at a temperature of 80°C to 100°C, and the coating speed is 60m / min to 100m / min.

[0018] Furthermore, the substrate layer is one of polyethylene terephthalate (PET) film, 1,4-polycyclohexylene dimethylene terephthalate film, polyethylene naphthalate (PEN) film, polyphenylene sulfide film, polystyrene (PS) film, polypropylene (PP) film, polyethylene (PE) film, polyvinyl chloride film, nylon film, and polyimide film.

[0019] Furthermore, the back coating layer comprises cellulose acetate propionate, polyvinyl acetal resin, polyvinyl butyral resin, a binder, a lubricant, a second filler, a cross-linking agent and an auxiliary agent.

[0020] Among them, the binder includes a high-adhesive resin such as polyester, polyurethane, etc.; the lubricant includes phosphate, zinc stearate, glycerol dioleate, glycerol monooleate, etc. The second filler has a self-cleaning effect and includes inorganic particles such as talc, kaolin, calcium carbonate, aluminum hydroxide, silicon dioxide, graphite, boron nitride, etc. The cross-linking agent includes isocyanate compounds, etc. The auxiliary agent includes one or more of a leveling agent, a dispersant, and an antistatic agent.

[0021] The beneficial effect of adopting the above further solution is that the purpose of the back coating is to prevent adverse effects such as stickiness or wrinkles caused by heating by a temperature-sensitive heating head during thermal transfer.

[0022] Furthermore, the preparation method of the back coating layer is to dissolve the components of the back coating layer to prepare a back coating layer coating liquid, and then use a 200-250-line ceramic anilox roller and a gravure coater to coat the back coating liquid on the substrate layer, dry it at 60°C to 100°C, and the coating speed is 60m / min to 100m / min.

[0023] Furthermore, the thickness of the substrate layer is 4 μm to 10 μm, preferably 4 μm to 6 μm; the thickness of the back coating layer is 0.1 μm to 0.5 μm, preferably 0.2 μm to 0.4 μm; the thickness of the color layer is 0.6 μm to 1.2 μm, preferably 0.8 μm to 1.0 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the layered structure of the thermal transfer carbon ribbon for the light box cloth of the present invention.

[0025] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0026] 1. Base material layer; 2. Color layer; 3. Back coating layer. DETAILED DESCRIPTION

[0027] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0028] Example 1

[0029] A thermal transfer ribbon for a light box cloth in this embodiment, such as Figure 1 As shown, it includes a substrate layer 1, a color layer 2 and a back coating layer 3, wherein the color layer 2 is arranged on one side of the substrate layer 1, and the back coating layer 3 is arranged on the other side of the substrate layer 1; the substrate layer 1 is made of polyethylene terephthalate film; the components of the color layer 2 include methacrylic acid copolymer A, methacrylic acid copolymer B, chloroacetic acid resin, pigment, wax (low molecular polyethylene wax) and a first filler (ultrafine silica).

[0030] The base material layer 1 is made of a polyethylene terephthalate (PET) film.

[0031] The molecular weight of the methacrylic acid copolymer A is 130,000, and the glass transition temperature Tg is 100° C. The molecular weight of the methacrylic acid copolymer B is 10,000, and the glass transition temperature Tg is 75° C. The vinyl chloride content of the chlorovinyl resin is 85%, and the polymerization degree K is 15.

[0032] The pigment is an organic pigment, and the particle size D50 of the pigment in the color layer is less than 0.1, and D100 is less than 0.3.

[0033] The raw materials of the color layer 2 are weighed in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 6 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 3 parts of chloroacetic acid resin C, 8 parts of pigment, 1 part of wax, and 1 part of the first filler. The preparation method of the color layer is as follows: dissolve the methacrylic acid copolymer A, methacrylic acid copolymer B, and chloroacetic acid resin in 2-butanone and toluene, then add the pigment, wax, and filler to dissolve and grind to prepare a color layer coating liquid, so that the pigment particle size D50 in the color layer coating liquid is less than 0.1 and D100 is less than 0.3, and the color layer is coated on the PET substrate layer using a ceramic anilox roller with 300 to 340 lines and a gravure coater, and dried at 80°C for 60 seconds and a coating speed of 80 m / min.

[0034] The back coating layer 3 weighs the raw materials in the following proportions: 60 parts of 2-butanone, 25 parts of toluene, 10 parts of cellulose acetate propionate, 0.5 parts of polyester resin, 0.3 parts of zinc stearate, 0.25 parts of phosphate, 0.2 parts of glycerol dioleate, 2 parts of isocyanate, 0.3 parts of talc, 0.2 parts of silicon dioxide, and 0.3 parts of antistatic agent; the preparation method of the back coating layer is to first dissolve cellulose acetate propionate and polyester resin in a mixed solvent of 2-butanone and toluene, then add zinc stearate, phosphate, glycerol dioleate, talc, silicon dioxide and antistatic agent, stir and mix for 2 hours, then add isocyanate, stir for 0.5 hours, and obtain the back coating coating liquid. Then use a 200-250 line ceramic anilox roller and a gravure coater to coat the back coating liquid on the PET substrate layer, dry at 100°C, dry for 60 seconds, and coat at a speed of 80 m / min.

[0035] When preparing the thermal transfer ribbon for the light box cloth, firstly, corona is applied on both sides of the substrate layer, a back coating is applied on one side of the substrate layer, and a color layer is applied on the other side of the substrate layer. The thickness of the substrate layer is 5 μm, the thickness of the back coating is 0.3 μm, and the thickness of the color layer is 0.9 μm.

[0036] Example 2

[0037] The color layer of this embodiment is prepared by weighing raw materials in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 7 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 2 parts of chloroacetic acid resin C, 8 parts of pigment, 1 part of wax, and 1 part of first filler. The rest is the same as in Embodiment 1.

[0038] Example 3

[0039] The color layer of this embodiment is prepared by weighing raw materials in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 7 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 3 parts of chloroacetic acid resin C, 8 parts of pigment, 0.4 parts of wax, and 0.6 parts of the first filler. The rest is the same as in Embodiment 1.

[0040] Example 4

[0041] The color layer of this embodiment is prepared by weighing raw materials in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 8 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 2 parts of chloroacetic acid resin C, 8 parts of pigment, 0.25 parts of wax, and 0.75 parts of the first filler. The rest is the same as in Embodiment 1.

[0042] Example 5

[0043] The color layer of this embodiment is prepared by weighing raw materials in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 8 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 2 parts of chloroacetic acid resin C, 8 parts of pigment, 0.5 parts of wax, and 0.5 parts of the first filler. The rest is the same as in Embodiment 1.

[0044] Example 6

[0045] The color layer of this embodiment is prepared by weighing raw materials in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 6 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 3 parts of chloroacetic acid resin C, 8 parts of pigment, 0.5 parts of wax, and 1.5 parts of the first filler. The rest is the same as in Embodiment 1.

[0046] Comparative Example 1

[0047] The raw materials of the color layer of this comparative example are weighed in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 6 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 3 parts of chloroacetic acid resin C, 8 parts of pigment, 2 parts of wax, and 0 part of the first filler. The rest is the same as in Example 1.

[0048] Comparative Example 2

[0049] The raw materials of the color layer of this comparative example are weighed in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 9 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 0 parts of chloroacetic acid resin C, 8 parts of pigment, 1 part of wax, and 1 part of the first filler. The rest is the same as in Example 1.

[0050] Comparative Example 3

[0051] The color layer of this comparative example is prepared by weighing raw materials in the following proportions: 40 parts of 2-butanone, 40 parts of toluene, 0 parts of methacrylic acid copolymer A, 1 part of methacrylic acid copolymer B, 9 parts of chloroacetic acid resin C, 8 parts of pigment, 1 part of wax, and 1 part of first filler. The rest is the same as in Example 1.

[0052] Comparative Example 4

[0053] In this comparative example, when preparing the color layer, the grinding time is half of that in Example 1. The rest is the same as in Example 1.

[0054] Test example

[0055] Test the transfer integrity of the resin ribbon, the adhesion of the pattern after printing, and the accelerated aging of the pattern after printing according to the following methods;

[0056] Transfer integrity test:

[0057] Use a thermal transfer printer (manufactured by Hunan Dingyi Intelligent Manufacturing Co., Ltd., model DTP-330) to print the required pattern on the outdoor light box cloth;

[0058] The formed images were visually checked and evaluated according to the following evaluation criteria:

[0059] A: No untransferred pattern area was observed in the image;

[0060] B: <0.1% of the untransferred pattern was observed in the image;

[0061] C: <1% of the untransferred pattern was observed in the image;

[0062] NG: >1% of the non-transferred pattern was observed in the image.

[0063] Adhesion test of transfer pattern:

[0064] Use a thermal transfer printer (manufactured by Hunan Dingyi Intelligent Manufacturing Co., Ltd., model DTP-330) to print the required pattern on the outdoor light box cloth.

[0065] The peeling test was carried out using a disc glass tester. After peeling, the exposed white area was less than 1%, and the evaluation was carried out according to the following evaluation criteria:

[0066] OK: After peeling, the exposed white area is less than 1%;

[0067] NG: After peeling, the exposed white area is greater than 1%.

[0068] Accelerated aging test:

[0069] Use a thermal transfer printer (manufactured by Hunan Dingyi Intelligent Manufacturing Co., Ltd., model DTP-330) to print the required pattern on the 3M white reflective film;

[0070] According to the operation method of "GB / T 16422.2-2014 Plastics Laboratory Light Source Exposure Test Method Part 2: Xenon Arc Lamp", test cycle: 1800h:

[0071] The formed images were visually confirmed and evaluated according to the following evaluation criteria:

[0072] OK: The pattern has no obvious fading;

[0073] NG: The pattern is obviously faded.

[0074] Use a thermal transfer printer (manufactured by Hunan Dingyi Intelligent Manufacturing Co., Ltd., model DTP-330) to print the required pattern on the outdoor light box cloth.

[0075] The glossiness of the color pattern of the light box cloth was tested using a gloss meter and evaluated according to the following evaluation criteria:

[0076] NG: glossiness <10%, glossiness >60%;

[0077] OK: Glossiness 15-60%.

[0078] Use a thermal transfer printer (manufactured by Hunan Dingyi Intelligent Manufacturing Co., Ltd., model DTP-330) to print the required pattern on the outdoor light box cloth.

[0079] The particle size of the color layer ink is measured using a particle size analyzer and evaluated using the following evaluation criteria:

[0080] OK: D50<0.1, D100<0.3;

[0081] NG:D50>0.1,D100>0.3.

[0082] The test results of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in the following table.

[0083] Table 1 Test results of Examples 1 to 6

[0084]

[0085] Table 2 Test results of Comparative Examples 1 to 4

[0086] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Transfer integrity test A NG A A Adhesion test OK OK NG OK Accelerated Aging Test OK OK NG OK Gloss test NG OK OK OK Color layer ink particle size test OK OK OK NG

[0087] As can be seen from Table 1 and Table 2, by comparing Example 1 with Comparative Example 1, it can be seen that the addition of fillers can effectively achieve the matte effect. This is because in the coating system, the ultrafine silica is dispersed in the paint film in the form of particles after addition. These particles will form tiny concave-convex structures on the surface of the paint film, destroying the original smoothness of the paint film. When light is irradiated on this uneven surface, diffuse reflection will occur, which will weaken the gloss of the material surface and enhance the matte effect.

[0088] By comparing Example 5 with Comparative Example 2, it can be seen that the addition of chloroacetic acid resin can improve the adhesion between the carbon ribbon and the printing substrate. The commonly used substrates of light box cloth, such as polyester fiber, also have a certain polarity. According to the principle of like dissolves like, the chloroacetic acid resin with stronger polarity can form better intermolecular force with the light box cloth substrate and improve the adhesion with the substrate.

[0089] By comparing Example 2 with Comparative Example 3, it can be seen that the addition of methacrylic acid copolymer A can effectively improve the service life of the carbon ribbon. The acrylic resin molecule contains a large number of carbon-carbon bonds (CC) and carbon-oxygen bonds (CO). These chemical bonds have high bond energy, making the molecular structure relatively stable and not easily destroyed by external environmental factors (such as ultraviolet rays, oxygen, temperature changes, etc.).

[0090] From the comparison between Example 1 and Comparative Example 4, it can be seen that the ink grinding particle size has a certain influence on the color uniformity and light transmittance of the carbon ribbon. When the ink particle size is small, the particles have relatively weak light shielding and scattering effects, making the film surface more transparent and able to better pass the light from the light box at night.

[0091] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0093] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A thermal transfer ribbon for light box cloth, characterized in that: It comprises a substrate layer, a color layer and a back coating layer, wherein the color layer is arranged on one side of the substrate layer, and the back coating layer is arranged on the other side of the substrate layer; The components of the color layer include methacrylic acid copolymer A, methacrylic acid copolymer B, chloroacetic acid resin, pigment, wax and a first filler.

2. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: The molecular weight of the methacrylic acid copolymer A is greater than 80,000, and the glass transition temperature Tg is greater than 90° C.; the molecular weight of the methacrylic acid copolymer B is less than 40,000, and the glass transition temperature Tg is less than 100° C.; the vinyl chloride content in the chlorovinyl resin is greater than 85%, and the degree of polymerization K is greater than 15.

3. The thermal transfer ribbon for light box cloth according to claim 2, characterized in that: The molecular weight of the methacrylic acid copolymer A is greater than 110,000, and the glass transition temperature Tg is greater than 100°C; the molecular weight of the methacrylic acid copolymer B is less than 10,000, and the glass transition temperature Tg is less than 80°C.

4. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: The pigment is an organic pigment, and the particle size D50 of the pigment in the color layer is less than 0.1, and D100 is less than 0.

3.

5. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: In terms of weight percentage, the methacrylic acid copolymer A accounts for 30% to 50% in the color layer, the methacrylic acid copolymer B accounts for 3% to 10% in the color layer, the chlorovinyl resin accounts for 3.75% to 15% in the color layer, the pigment accounts for 30% to 50% in the color layer, the wax accounts for 0.5% to 5% in the color layer, and the first filler accounts for 2.5% to 10% in the color layer.

6. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: The preparation method of the color layer comprises the following steps: dissolving and grinding methacrylic acid copolymer A, methacrylic acid copolymer B, chloroacetic acid resin, pigment, wax and filler to prepare a color layer coating liquid, wherein the pigment particle size D50 in the color layer coating liquid is less than 0.1 and D100 is less than 0.3; using a ceramic anilox roller with 300 to 340 lines and a gravure coater to coat the color layer on a substrate layer; and drying the mixture at a temperature of 80 to 100° C. and a coating speed of 60 m / min to 100 m / min.

7. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: The substrate layer is one of polyethylene terephthalate film, 1,4-polycyclohexylene dimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polyethylene film, polyvinyl chloride film, nylon film and polyimide film.

8. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: The components of the back coating layer include cellulose acetate propionate, polyvinyl acetal resin, polyvinyl butyral resin, a binder, a lubricant, a second filler, a cross-linking agent and an auxiliary agent.

9. The thermal transfer ribbon for light box cloth according to claim 8, characterized in that: The preparation method of the back coating layer is as follows: dissolving the components of the back coating layer into a back coating liquid, and then using a 200-250-line ceramic anilox roller and a gravure coater to coat the back coating liquid on the substrate layer, drying at 60°C to 100°C, and a coating speed of 60m / min to 100m / min.

10. The thermal transfer ribbon for light box cloth according to claim 1, characterized in that: The thickness of the substrate layer is 4 μm to 10 μm, the thickness of the back coating layer is 0.1 μm to 0.5 μm, and the thickness of the color layer is 0.6 μm to 1.2 μm; Alternatively, the thickness of the substrate layer is 4 μm to 6 μm, the thickness of the back coating layer is 0.2 μm to 0.4 μm, and the thickness of the color layer is 0.8 μm to 1 μm.

Images