Efficient laser thermal transfer ribbon based on gas pressure driving ink layer

Abstract

The invention belongs to the technical field of laser heat transfer printing, and particularly relates to an efficient laser heat transfer printing thermal transfer ribbon based on a gas pressure driving ink layer. The laser thermal transfer ribbon comprises a base material, a laser thermal expansion layer and an ink layer which are arranged in sequence. Through the arrangement of the laser thermal expansion layer, the printing ink layer is driven by gas pressure, the transfer printing efficiency is improved, the adaptability to a printing stock is enhanced, the quality of a transfer printing pattern is improved, and complete transfer of the printing ink layer is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser thermal transfer, and particularly relates to an efficient laser thermal transfer ribbon based on gas pressure driving an ink layer. Background Art

[0002] In traditional thermal transfer technology, there are problems such as low transfer efficiency, limited adaptability to substrates, unsatisfactory transfer pattern quality (such as low clarity, insufficient color saturation, uneven line edges), and incomplete ink transfer.

[0003] In commercial printing (such as label and ticket printing), existing ribbons may not meet the requirements of high-speed printing, and the printed patterns are prone to wear and fade; in personalized customized printing (such as customized gift and decorative painting printing), it is difficult to achieve printing effects with high color accuracy and rich color levels; in industrial identification printing, the adhesion and corrosion resistance to different material substrates are insufficient. Low transfer efficiency leads to a long production cycle and increased production costs, which is more obvious especially in large-scale printing production. Limited adaptability to substrates restricts the application of ribbons on different material surfaces, requires frequent ribbon replacement or adjustment of printing parameters, and reduces production efficiency. Unsatisfactory pattern quality affects the aesthetics and readability of printed products, reduces the added value of products, and cannot meet the requirements in fields with high printing quality requirements (such as art printing and high-resolution image printing). Incomplete ink transfer will cause ink waste, increase the use cost, and may also affect the integrity and durability of the printed pattern.

[0004] In the prior art:

[0005] 1. When optimizing the ink formula, new components may chemically react with other layers, affecting the overall performance of the ribbon; the increased cost may make the product lose price competitiveness; and it cannot fundamentally solve the problems of transfer efficiency and substrate adaptability.

[0006] 2. Although improving the substrate may improve some properties, it is difficult to meet the requirements of multiple aspects simultaneously. For example, increasing the strength may reduce the flexibility, affecting the performance of the ribbon during bending or winding; moreover, the change of the substrate may require re-optimizing the entire coating process, increasing the technical difficulty and cost.

[0007] 3. Adjusting the laser parameters requires high equipment requirements, and in actual production, the material properties of different batches of ribbon materials may have certain fluctuations, resulting in the pre-set laser parameters not always maintaining the best transfer effect, affecting production efficiency and product quality stability.

[0008] Laser thermal transfer technology has been widely used in many fields due to its advantages such as high precision and non-contact printing. With the continuous improvement of market requirements for printing quality and efficiency, the optimization of ribbon performance has become a key research direction. Among them, gas pressure-driven laser thermal transfer specifically refers to: using a laser to irradiate a specific layer of the ribbon (laser thermal expansion layer), generating gas, and pushing the ink layer onto the substrate through the pressure formed by gas accumulation for printing technology. Summary of the Invention

[0009] To solve the deficiencies of the prior art, the present invention provides an efficient laser thermal transfer ribbon based on gas pressure-driven ink layer. By setting the laser thermal expansion layer, the present invention realizes gas pressure-driven ink layer, improves the transfer efficiency, enhances the adaptability to the substrate, improves the quality of the transferred pattern, and ensures the complete transfer of the ink layer.

[0010] The technical solutions provided by the present invention are as follows:

[0011] An efficient laser thermal transfer ribbon based on gas pressure-driven ink layer, comprising a substrate, a laser thermal expansion layer, and an ink layer arranged in sequence.

[0012] Based on the above technical solutions, high-pressure gas can be generated by the laser thermal expansion layer under the action of a laser, driving the ink layer to spray onto the substrate for transfer.

[0013] PET Substrate

[0014] Material Selection: Select a transparent polyethylene terephthalate film, polypropylene film, polyethylene naphthalate film, polyethylene film, polyvinyl alcohol film, or polymethyl methacrylate film with a thickness of 4-10 microns. Preferably, polyethylene terephthalate (PET) film is used as the support layer, which has good mechanical strength, can withstand various stresses during the preparation, storage, transportation, and use of the ribbon, and is not easily broken or deformed; it has high chemical stability, can resist the erosion of ink, solvents, and other chemical substances, and ensures the stable performance of the ribbon in different chemical environments; it has good dimensional stability, is not easily stretched or shrunk when the temperature and humidity change, and ensures the transfer accuracy; it has a high surface flatness, which is beneficial to the uniform coating of the laser thermal expansion layer and the ink layer.

[0015] Surface Treatment Method: The surface of the substrate is treated by corona treatment to make the surface dyne value reach 42-50, enhancing its adhesion to the photothermal conversion layer. The corona treatment time is 5-10 seconds, the power is 1-3 kW, and the next coating operation is carried out immediately after treatment to prevent surface contamination from affecting the adhesion.

[0016] Laser Thermal Expansion Layer

[0017] Material selection: It is composed of gas substances generated by low-temperature decomposition (ammonium bicarbonate, mass fraction 30%-50%), low-temperature foaming substances (azodicarbonamide microcapsules, mass fraction 20%-35%), light-absorbing materials (carbon nanotubes and graphene composite with a weight ratio of (8-15):(3-8), mass fraction 10%-20%), and binders (acrylic resin, mass fraction 10%-20%).

[0018] Based on the above technical solution, ammonium bicarbonate decomposes at low temperature to generate gases such as carbon dioxide and ammonia, and azodicarbonamide microcapsules release gases by foaming at a specific temperature. The generation of these gases provides a driving force for the transfer of the ink layer; the carbon nanotubes and graphene composite have excellent light-absorbing properties, can efficiently absorb laser energy and convert it into heat energy, triggering low-temperature decomposition and foaming reactions; acrylic resin as a binder ensures the firm adhesion of the laser thermal expansion layer on the support layer, and at the same time has good flexibility and heat resistance.

[0019] Preparation and coating process:

[0020] For ammonium bicarbonate, it is thoroughly ground and mixed with a small amount of stabilizer (such as calcium stearate, mass fraction 0.5%-1% of ammonium bicarbonate) in a mortar for 10-15 minutes to evenly disperse the stabilizer on the surface of ammonium bicarbonate particles. Then it is slowly added to the acrylic resin solution (acrylic resin dissolved in an appropriate amount of organic solvent such as toluene, mass fraction 10%-20%), and dispersed for 20-30 minutes at a rotation speed of 1000-1500 rpm using a high-speed disperser to form a uniform coating.

[0021] For azodicarbonamide microcapsules, they are prepared by a microencapsulation process:

[0022] Mix azodicarbonamide with the encapsulating material (a gelatin - gum arabic composite system, with the mass ratio of gelatin to gum arabic being 1:1 - 2:1) in a certain proportion. First, prepare the encapsulating material into an aqueous solution with a mass fraction of 5% - 10%, and stir and dissolve it at 40 - 50 °C. Add azodicarbonamide to the encapsulating material solution, and use an emulsifier to emulsify it at a rotation speed of 5000 - 8000 rpm for 10 - 15 minutes to form a stable water - in - oil emulsion. Then, in the emulsified system, slowly dropwise add a cross - linker (glutaraldehyde, with a dosage of 1% - 3% of the mass of the encapsulating material), while using a constant - temperature water bath to keep the system temperature at 40 - 50 °C, and continuously stir (stirring speed 300 - 500 rpm) for 3 - 5 hours to cause the cross - linking reaction of the encapsulating material to form microcapsules. After the reaction ends, use a centrifuge to centrifuge at a rotation speed of 3000 - 5000 rpm for 10 - 15 minutes, collect the microcapsule precipitate, wash it with deionized water 2 - 3 times to remove unreacted raw materials. Finally, disperse the washed microcapsules in an acrylic resin solution (i.e., the above - mentioned coating formed by ammonium bicarbonate and acrylic resin), and use an ultrasonic disperser to disperse it at an ultrasonic power of 200 - 300 W for 10 - 15 minutes to prepare a laser thermal expansion layer coating.

[0023] Add the carbon nanotube and graphene composite light - absorbing material to the laser thermal expansion layer coating, and use an ultrasonic dispersion device to disperse it at an ultrasonic power of 300 - 500 W for 30 - 60 minutes to ensure the uniform dispersion of the light - absorbing material. Use a gravure coater for coating, with a coating speed of 100 - 200 m / min, a drying temperature of 60 - 100 °C, and the coating thickness controlled at 0.5 - 2 μm.

[0024] Based on the above - mentioned technical solution, the carbon nanotube and graphene composite light - absorbing material can achieve efficient photothermal conversion.

[0025] Ink layer

[0026] Material selection: The ink is composed of a low - melting - point resin (paraffin - based resin, mass fraction 40% - 60%), pigments (such as carbon black, organic pigments, mass fraction 15% - 30%), solvents (ethanol and acetone, mass fraction 10% - 20%), and additives (such as dispersants, stabilizers, etc., mass fraction 5% - 10%).

[0027] Based on the above - mentioned technical solution, the paraffin - based resin has a low melting point and is easy to soften and flow under the action of the heat and gas pressure generated by the laser thermal expansion layer, which is beneficial to the transfer of the ink; the pigments provide the required colors to meet different printing color requirements; the solvents adjust the viscosity and drying speed of the ink, facilitating the coating and transfer processes; additives such as dispersants (polymer dispersants, mass fraction 3% - 6% of the mass of the pigment) ensure the uniform dispersion of the pigments, and stabilizers (antioxidants, mass fraction 1% - 3% of the total mass of the ink) improve the stability of the ink during storage and use.

[0028] Coating parameters and thickness control: The ink layer is coated by a gravure coater. The coating speed is 100 - 200 m / min, the drying temperature is 60 - 100 °C, and the thickness is controlled within 2 μm to ensure complete transfer to the substrate under gas pressure drive.

[0029] For substances that decompose at low temperatures to produce gaseous substances, other ammonium salts (such as ammonium chloride) or metal carbonates (such as magnesium carbonate) can also be selected.

[0030] For low-temperature foaming substances, sulfonyl hydrazide foaming agents can also be selected.

[0031] For low-melting-point resins, polyester resins or polyamide resins can also be selected.

[0032] For dispersants, low-molecular-weight surfactants can also be selected.

[0033] For stabilizers, ultraviolet absorbers can also be selected.

[0034] The present invention also provides a method for preparing an efficient laser thermal transfer carbon ribbon based on gas pressure driving an ink layer, comprising the following steps: corona treating the surface of the substrate, and then sequentially preparing a laser thermal expansion layer and an ink layer.

[0035] The present invention also provides the application of an efficient laser thermal transfer carbon ribbon based on gas pressure driving an ink layer, using ultraviolet light as the laser source for full transfer.

[0036] The present invention significantly improves the transfer efficiency, enhances the adaptability to various substrates, greatly improves the pattern quality, ensures complete transfer of the ink layer, and at the same time maintains a reasonable cost to meet diverse printing requirements.

[0037] The beneficial effects of the present invention are specifically as follows:

[0038] 1. In terms of transfer efficiency, by driving the transfer of the ink layer through gas pressure, compared with the traditional laser thermal transfer method, the transfer efficiency is increased by 50% - 80%, greatly shortening the printing time and improving the production efficiency, especially suitable for large-scale and high-speed printing requirements.

[0039] 2. In terms of pattern quality, the clarity benefits from the uniform gas pressure pushing the transfer of the ink layer, making the edges of the lines clearer and the pattern details better presented. The clarity is improved by 30% - 60% compared with the prior art. The improvement in color saturation stems from the optimization of the ink layer formula and uniform transfer, making the colors more vivid and saturated. The color saturation is increased by 20% - 30% compared with the prior art. The improvement in the straightness of the line edges is mainly due to the smoothness of the gas pressure drive, reducing the irregularities during the ink transfer process. The edge straightness is improved by 30% - 50% compared with the prior art.

[0040] 3. In terms of ink transfer rate, the gas pressure generated by the laser thermal expansion layer can ensure that the ink layer is almost completely transferred, and the ink transfer rate reaches more than 90%, which is 10%-20% higher than that of the prior art, reducing ink waste and lowering the usage cost.

[0041] 4. In terms of the adaptability of the printing substrate, the optimized ink layer formula and the gas pressure driving method enable the carbon ribbon to better adapt to printing substrates of different materials, achieving good adhesion and transfer effects on various surfaces, broadening the application range of the carbon ribbon, and reducing printing problems caused by different printing substrates. Description of the Drawings

[0042] Figure 1 It is a schematic structural diagram of an efficient laser thermal transfer carbon ribbon based on gas pressure driving the ink layer provided by the present invention.

[0043] Figure 2 It is a comparison chart of the printing effects of Example 1 and Comparative Example 1.

[0044] Appendix Figure 1 In the following, the structures represented by each reference numeral are listed as follows:

[0045] 1. Substrate; 2. Laser thermal expansion layer; 3. Ink layer. Detailed Embodiments

[0046] 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.

[0047] Unless otherwise specified, the test methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, are reagents and materials that can be obtained from commercial channels.

[0048] Preparation of azodicarbonamide and the encapsulating material:

[0049] A gelatin - gum arabic composite system, with gelatin and gum arabic mixed in a mass ratio of 1.5:1. The encapsulating material is first prepared into an aqueous solution with a mass fraction of 7.5% and stirred and dissolved at 45°C. Azodicarbonamide is added to the encapsulating material solution, and emulsified with an emulsifier at a rotation speed of 6000 rpm for 12 minutes to form a stable water-in-oil emulsion. Then, in the emulsified system, a crosslinking agent (glutaraldehyde, with a dosage of 2% of the mass of the encapsulating material) is slowly added dropwise, while maintaining the system temperature at 45°C with a constant temperature water bath and continuously stirring (stirring speed 400 rpm) for 4 hours to cause the crosslinking reaction of the encapsulating material to form microcapsules. After the reaction, the microcapsules are centrifuged at a rotation speed of 4000 rpm for 12 minutes, and the microcapsule precipitate is collected and washed 3 times with deionized water to remove unreacted raw materials.

[0050] In a specific embodiment, as Figure 1 shown, the high-efficiency laser thermal transfer carbon ribbon based on gas pressure driving the ink layer includes a substrate 1, a laser thermal expansion layer 2, and an ink layer 3 arranged in sequence.

[0051] Example 1

[0052] Support layer (PET): A 6-micron PET film is selected and subjected to corona treatment. After treatment, the surface dyne value of the film material is not less than 48.

[0053] Laser thermal expansion layer

[0054] 40 parts of ammonium bicarbonate and 0.2 part of calcium stearate are ground and mixed, and then added to 100 parts of a toluene solution of acrylic resin with a mass fraction of 15%. High-speed dispersion is carried out for 25 minutes. 30 parts of azodicarbonamide microcapsules (prepared according to the above microencapsulation process) are dispersed in the toluene solution of acrylic resin, and ultrasonic dispersion is carried out for 12 minutes. 15 parts of a carbon nanotube and graphene composite light-absorbing material (mass ratio 1:1) are added to the laser thermal expansion layer coating, and ultrasonic dispersion is carried out for 45 minutes to obtain the coating. Coating is carried out with a doctor blade coater at a speed of 100 m / min and dried at 70 °C, with a thickness of 0.7 μm.

[0055] Ink layer

[0056] 50 parts of paraffin-based resin (an optional brand model is Kraton Polystrand 3110), 20 parts of carbon black pigment, 10 parts of ethanol, 5 parts of acetone, 5.0 parts of a polymer dispersant (an optional brand model is BYK-163 of BYK), 2.0 parts of an antioxidant (an optional brand model is Irganox 1010 of BASF). After mixing, coating is carried out with a gravure coater at a speed of 100 m / min and dried at 90 °C, with a thickness of 1.2 μm.

[0057] Example 2

[0058] Support layer (PET): The same as in Example 1.

[0059] Laser thermal expansion layer: The same as in Example 1.

[0060] Ink layer

[0061] 45 parts of paraffin-based resin (an optional brand model is Kraton Polystrand 3110), 25 parts of organic pigment (phthalocyanine blue), 12 parts of ethanol, 8 parts of acetone, 7.0 parts of a polymer dispersant (an optional brand model is BYK-163 of BYK), 3.0 parts of an antioxidant (an optional brand model is Irganox 1010 of BASF). After mixing, coating is carried out with a gravure coater at a speed of 100 m / min and dried at 85 °C, with a thickness of 1.5 μm (for color image printing).

[0062] Comparative Example 1

[0063] The thermal transfer ribbon with the brand of S103 from Hunan Dingyi

[0064] Comparative Example 2

[0065] Referring to Example 1, the difference is that the laser thermal expansion layer is not provided

[0066] Comparative Example 3

[0067] Referring to Example 1, the difference is that the light-absorbing material is not added to the laser thermal expansion layer

[0068] Performance Test

[0069] 1. Transfer Efficiency Test

[0070] Test Equipment and Method: Using a high-precision timer and a laser power meter, measure the time required for the ribbon to transfer a specific pattern (such as a 10 cm × 10 cm solid black pattern) on standard paper at a fixed laser wavelength (such as 980 nm) and power (8 W). The transfer efficiency is calculated by the area transferred per unit time (cm 2 / s).

[0071] Sample Quantity and Statistical Analysis: Each example and comparative example is tested 5 times, and the average value is taken as the final result. The standard deviation is calculated to evaluate the dispersion degree of the data

[0072] 2. Pattern Quality Test

[0073] Clarity Evaluation

[0074] Test Equipment and Method: Use a high-resolution optical microscope (magnification 500 - 1000 times) to observe the line edges of the transferred pattern and measure the line width deviation. At the same time, use professional image analysis software (such as ImageJ) to calculate the clarity parameters of the pattern, such as the edge gradient value and the modulation transfer function (MTF) value

[0075] Quantification Standard: The line width deviation within ±5%, the edge gradient value greater than 50, and the MTF value greater than 0.4 at a specific frequency (such as 10 lp / mm) are regarded as good clarity

[0076] Color Saturation Evaluation

[0077] Test Equipment and Method: Use a spectrophotometer (such as X-Rite i1Pro 2) to measure the color spectral reflectance of the transferred pattern, and calculate the color saturation parameters (such as the range of a* and b coordinate values and the C value) according to the color space (such as sRGB, Adobe RGB)

[0078] Quantification standard: When the coordinate values of a* and b are within a specific threshold range (for example, a is between -50 and 50, and b is between -50 and 50) and the C value is greater than 50, it is considered that the color saturation is high.

[0079] Evaluation of the neatness of the line edges

[0080] Testing equipment and methods: Observe the line edge morphology of the transfer pattern through a scanning electron microscope (SEM), and measure the roughness and irregularity of the edges. At the same time, use image analysis software to calculate the serration parameter of the edge.

[0081] Quantification standard: When the edge roughness is less than 0.5 μm and the serration parameter is less than 0.1, it is considered that the line edge neatness is good.

[0082] 3. Ink transfer rate test

[0083] Testing method: Weigh the mass of the carbon ribbon accurately before and after transfer respectively, calculate the mass difference before and after ink transfer, and the ink transfer rate = (ink mass before transfer - ink mass after transfer) ÷ ink mass before transfer × 100%.

[0084] Sample quantity and statistical analysis: Each example and comparative example are tested 5 times, and the average value is taken as the final result, and the standard deviation is calculated to evaluate the reliability of the data.

[0085] 4. Substrate adaptability test

[0086] Testing of substrates with different materials: Select substrates of various materials such as paper (such as coated paper, thermal paper, and coated paper is uniformly used in the test items), plastic films (such as PET film, PP film, and PET is uniformly used in the test items), and leather, and conduct transfer tests under the same laser thermal transfer parameters.

[0087] Adhesion test method

[0088] Tape peeling test: After transfer, paste a standard tape (such as 3M tape) on the surface of the pattern, roll it 3 times with a 2 kg roller, and then quickly peel the tape in a 90° direction, observe the pattern peeling situation, and calculate the percentage of the peeling area. When the peeling area is less than 5%, it is considered that the adhesion is good.

[0089] Abrasion resistance test: Fix the transferred substrate on a friction testing machine, use a rubber friction head, apply a pressure of 5 N, and reciprocate at a speed of 100 mm / s for 100 times, observe the pattern wear situation, and rate it according to the wear degree (such as 1 - 5 levels, 5 levels means no wear, and 1 level means severe wear).

[0090] Test results

[0091]

[0092] As shown Figure 2 in the figure, it is a comparison diagram of the printing effects of Example 1 and Comparative Example 1. The left part corresponds to Example 1, and the right part corresponds to Comparative Example 1. Both are partial barcodes. It can be seen that Example 1 is higher than Comparative Example 1 in terms of both clarity and edge neatness, and the ink is fully transferred.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-efficiency laser thermal transfer ribbon based on a gas pressure driven ink layer, characterized in that: The invention comprises a substrate, a laser thermal expansion layer and an ink layer which are arranged in sequence.

2. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 1, characterized in that: The laser thermal expansion layer comprises the following components in percentage by mass: 30%-50% of a substance that decomposes at low temperature to generate gas, 20%-35% of a substance that foams at low temperature, 10%-20% of a light absorbing material, and 10%-20% of a bonding agent.

3. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 2, characterized in that: The low-temperature decomposition gas-generating substance is selected from ammonium bicarbonate, ammonium chloride or magnesium carbonate; The low-temperature foaming substance is selected from azodicarbonamide microcapsules or sulfonylhydrazide foaming agents; The binder is selected from acrylic resin.

4. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 3, characterized in that: The light absorbing material comprises carbon nanotubes and graphene in a weight ratio of (8-15):(3-8).

5. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 1, characterized in that: The thickness of the laser thermal expansion layer is 0.5-2 μm.

6. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 1, characterized in that: The substrate is selected from a transparent polyethylene terephthalate film, a polypropylene film, a polyethylene naphthalate film, a polyethylene film, a polyvinyl alcohol film or a polymethyl methacrylate film; The thickness of the substrate is 4-10 μm.

7. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 1, characterized in that: The ink layer is prepared from an ink coating liquid, which includes the following components in mass percentage: 40%-60% low melting point resin, 15%-30% pigment, 10%-20% solvent, and 5%-10% additive; the thickness of the ink layer is 1-3 μm.

8. The high-efficiency laser thermal transfer ribbon based on gas pressure driven ink layer according to claim 7, characterized in that: The low melting point resin is a paraffin-based resin, a polyester resin or a polyamide resin; The pigment is carbon black or an organic pigment; The solvent is selected from one or more of ethanol and acetone, ethyl acetate or butanone; The additive is a dispersant or a stabilizer.

9. A method for preparing a high-efficiency laser thermal transfer ribbon based on a gas pressure driven ink layer according to any one of claims 1 to 8, characterized in that: The following steps are involved: The surface of the substrate is subjected to corona treatment, and then a laser thermal expansion layer and an ink layer are prepared in sequence.

10. An application of a high-efficiency laser thermal transfer ribbon based on a gas pressure driven ink layer according to any one of claims 1 to 8, characterized in that: Ultraviolet light is used as the laser source for full transfer.

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