Thermosensitive photopaper for color printing and method for producing the same
By introducing a composite structure of phase change polymer and high refractive index colloidal microspheres into thermal paper, the problems of low resolution and color printing of thermal paper are solved, achieving structural color rendering with high color visibility, which is suitable for commercial thermal printers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2024-05-15
- Publication Date
- 2026-06-02
AI Technical Summary
Existing thermal paper suffers from low resolution, slow response speed, and difficulty in achieving color printing. Furthermore, the color developer bisphenol A is harmful to health, and the color tends to fade over time.
Phase change polymers are introduced into a template assembled from colloidal microspheres and high-refractive-index colloidal microspheres. A composite structure of cavity/high-refractive-index colloidal microspheres/cavity is formed by selective etching. Color development is achieved by utilizing the crystallization-melting transition of the phase change polymer under thermal stimulation. The color development layer uses high-refractive-index colloidal microspheres to present structural color.
It achieves stability and durability in color printing, with fast response speed, high resolution, and environmentally friendly and harmless color developer.
Smart Images
Figure CN118372573B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a thermal photonic paper for color printing and its preparation method, belonging to the field of printing technology. Background Technology
[0002] Thermal paper is a special communication medium that changes color when heated, thus forming text, images, and other visual representations. Its elimination of ink cartridges and toner significantly reduces printing costs, making it widely used in printers, cash registers, barcode labelers, and other equipment, representing a significant development direction in current printing technology. However, current thermal paper manufacturing technology primarily uses bisphenol A (BPA) as the color developer, which can potentially affect human health. Furthermore, images on thermal paper tend to fade over time and are sensitive to chemicals.
[0003] Photonic crystals are a class of artificial periodic dielectric structures with photonic bandgap characteristics. Their tunable optical properties make them promising for applications in inkjet printing, photonic printing, and information encryption. Among them, thermally responsive photonic crystals control optical properties through heat, offering the most promising strategy for thermal printing. The color of the photonic crystal structure can be changed by adjusting structural parameters, resulting in excellent stability and durability. However, photonic crystal-based thermal paper still faces some challenges in application, such as low resolution, slow response speed, and difficulty in achieving color printing.
[0004] Therefore, we introduced a phase change polymer into a template assembled from colloidal microspheres and high-refractive-index colloidal microspheres, and selectively etched it to form a cavity / high-refractive-index colloidal microsphere / cavity composite structure. The top cavity structure exhibits structural color characteristics due to its interaction with light. Under thermal stimulation, the phase change polymer undergoes a crystallization-melting transition, causing the top cavity structure to collapse and become transparent, thus revealing the structural color of the intermediate color layer. Because the color layer uses high-refractive-index colloidal microspheres, it possesses a structural color with high color visibility. The prepared structure was printed on a commercial thermal printer, enabling color printing; this technology has not been previously reported in the field of thermal printing. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing thermal photonic paper for color printing. A phase change polymer is introduced into a template assembled from colloidal microspheres and high-refractive-index colloidal microspheres, and a cavity / high-refractive-index colloidal microsphere / cavity composite structure is formed by selective etching. The top cavity structure exhibits structural color characteristics due to its interaction with light. Under thermal stimulation, the phase change polymer undergoes a crystallization-melting transition, causing the top cavity structure to collapse and become transparent, thus revealing the structural color of the intermediate color layer. Because the color layer uses high-refractive-index colloidal microspheres, it possesses a structural color with high color visibility. The prepared structure can be printed in color using a commercial thermal printer.
[0006] This method is simple and easy to implement. The resulting thermal paper exhibits stable color development after thermal printing, is environmentally friendly, and is solvent-resistant, making it a promising candidate for wide-ranging applications in the field of color commercial printing.
[0007] The technical solution adopted in this invention is as follows: The method for preparing thermal photonic paper for color printing, as described in this invention, includes the following steps:
[0008] (1) Assemble colloidal microspheres of different particle sizes on a glass substrate to form a photonic crystal array or quasi-crystal array template, then assemble high refractive index microspheres, and then assemble colloidal microspheres of the same particle size to construct a three-layer template.
[0009] (2) The precursor solution of the phase change polymer is filled into the voids of the template and cured by UV light to obtain the composite structure.
[0010] (3) The composite structure is selectively etched to form a thermal photonic paper.
[0011] In the preparation method of thermal photonic paper for color printing described in this invention, the material is filled into the voids of the template by a precursor solution, cured under ultraviolet light to obtain a composite structure of phase change polymer and template, and then formed into a "sandwich structure" after selective etching.
[0012] In the preparation method of thermal photonic paper for color printing according to the present invention, the precursor solution is a mixture containing a crystalline monomer with double bonds, a crosslinking agent monomer and a photoinitiator.
[0013] In the preparation method of the thermal photonic paper for color printing according to the present invention, the precursor solution is obtained by the following method: a mixture of a double-bonded crystalline monomer and a crosslinking agent monomer in a mass ratio of 100:(1-10) and a photoinitiator (0.1%-3% of the total monomer mass of the double-bonded crystalline monomer and the crosslinking agent monomer) is thoroughly mixed and stored in the dark. Preferably, the mass ratio of the double-bonded crystalline monomer and the crosslinking agent monomer is 100:1.5; and the photoinitiator is 1% of the total monomer mass.
[0014] In the preparation method of thermal photonic paper for color printing according to the present invention, the crystalline monomer with double bonds includes one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate, stearate acrylate, eicosyl acrylate, dodecyl acrylate, lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, stearate methacrylate, eicosyl methacrylate, dodecyl methacrylate, 1H,1H-perfluorooctyl acrylate, and dodecafluoroheptyl acrylate. Preferably, it is 1H,1H-perfluorooctyl acrylate.
[0015] In the method for preparing thermal photonic paper for color printing according to the present invention, the crosslinking agent monomer includes one or two of 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, and trimethylolpropane trimethacrylate. Preferably, it is 1,6-hexanediol diacrylate.
[0016] In the preparation method of thermal photonic paper for color printing according to the present invention, the colloidal microspheres are inorganic colloidal microspheres or polymer colloidal microspheres. The inorganic colloidal microspheres are silica microspheres; the polymer colloidal microspheres are polystyrene colloidal microspheres or polymethyl methacrylate colloidal microspheres. The high refractive index colloidal microspheres are sulfur-containing microspheres, zinc sulfide, copper oxide, titanium dioxide, or silica-coated polystyrene microspheres.
[0017] Preferably, the colloidal microspheres are silica microspheres; the high refractive index colloidal microspheres are sulfur-containing microspheres.
[0018] The particle size of the colloidal microspheres ranges from 100 to 400 nm.
[0019] Preferably, the particle size range is 150-300 nm.
[0020] The aforementioned inorganic colloidal microspheres, polymer colloidal microspheres, and high refractive index colloidal microspheres can all be prepared using methods disclosed in the prior art.
[0021] Furthermore, the method of constructing a photonic crystal array using colloidal microspheres can adopt the methods disclosed in the prior art, such as heat assembly, dip-coating, vertical deposition, blade coating, or spin coating.
[0022] Furthermore, quasi-crystal arrays can be obtained by disordered assembly of colloidal microspheres, using methods disclosed in existing technologies such as drop coating or spray coating.
[0023] In the above technical solution, the method for selectively removing the colloidal microsphere template is either calcination or chemical etching.
[0024] A thermal photonic paper for color printing has a "sandwich structure" consisting of a thermal layer, a color developing layer, and a protective layer, primarily composed of a phase change polymer. The phase change polymer is obtained by curing a crystalline monomer with double bonds and a crosslinking agent monomer.
[0025] The thermal layer and the protective layer are cavity structures composed of phase change polymers with significant phase change characteristics;
[0026] The color-developing layer is a photonic crystal structure or quasi-crystal structure composed of high-refractive-index microspheres.
[0027] The beneficial effects of this invention are as follows: This invention introduces a phase change polymer (PCP) as the main component into a template assembled from colloidal microspheres and high-refractive-index colloidal microspheres, and forms a composite structure of cavity / high-refractive-index colloidal microspheres / cavity through selective etching. The PCP exhibits significant rigidity in its crystalline state, endowing the top cavity structure with structural color properties. Under thermal stimulation, the PCP undergoes a crystallization-melting transition, causing the top cavity structure to collapse and become transparent, thus revealing the structural color of the intermediate color layer. The use of high-refractive-index colloidal microspheres in the color layer gives it a structural color with high color visibility. Different structural colors can be achieved by controlling the particle size of the colloidal microspheres in the color layer. Its unique color development mechanism endows it with excellent stability and durability. Through optimization of the phase change temperature, it can be used for color printing in commercial thermal printers, with fast response speed and high resolution. Attached Figure Description
[0028] Figure 1 The image in the middle is a scanning electron microscope (SEM) image of the surface of the thermal photonic paper described in Example 1.
[0029] Figure 2 The image shown is a photograph taken with the thermal photonic paper described in Example 1, along with the corresponding reflection spectrum.
[0030] Figure 3 (a) is a digital photograph of the single-layer photonic paper described in Example 2; (b) is a digital photograph of the single-layer photonic paper described in Example 2 after thermal induction.
[0031] Figure 4 The change in reflectance spectrum of the single-layer photonic paper described in Example 2 before and after thermal induction.
[0032] Figure 5 The transmission spectrum changes of the single-layer photonic paper described in Example 2 before and after thermal induction.
[0033] Figure 6 This is a SEM image of the single-layer photonic paper after thermal induction as described in Example 2.
[0034] Figure 7 The image shows the DSC curve of the single-layer photonic paper described in Example 2 during the heating process.
[0035] Figure 8 The image shows the structural color of the thermal photosensitive paper used for color printing described in Example 3 after thermal induction at 60°C.
[0036] Figure 9 The image is printed using a commercial thermal printer on the thermal photonic paper described in Example 1. Detailed Implementation
[0037] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.
[0038] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available or can be prepared by conventional methods.
[0039] Example 1
[0040] The preparation of thermal photonic paper for color printing includes the following steps:
[0041] 1. Template preparation
[0042] A multilayer microsphere template was prepared by spraying an ethanol dispersion of silica microspheres with a mass fraction of 10% and a particle size of 301 nm onto a glass substrate using a spray gun. Then, sulfur-containing microspheres with a particle size of 265 nm were sprayed onto the glass slide, followed by the spraying of silica microspheres with a particle size of 301 nm.
[0043] 2. Preparation of precursor solution
[0044] 1H,1H-perfluorooctyl acrylate and 1,6-hexanediol diacrylate (HDDA) were stirred and mixed evenly at a mass ratio of 100:1.5. Photoinitiator 1173, with a total mass fraction of 1% of the two, was added and ultrasonically dispersed to ensure uniform mixing. The mixture was then placed away from light.
[0045] 3. Preparation of thermal photonic paper
[0046] The uniformly dispersed precursor solution slowly penetrates into the gaps and surface of the multilayer microsphere template, initiating polymerization under ultraviolet light to form a composite photonic film. It is then immersed in a 4% hydrofluoric acid solution for 2 hours to etch away the SiO2 template, yielding thermal photonic paper.
[0047] Figure 1 The image shown in the middle is a surface SEM image of the thermal photonic paper described in Example 1. The pores are evenly distributed on the surface of the photonic paper, with regular morphology and uniform size.
[0048] Figure 2(a) is a photograph of the thermal photonic paper taken at a vertical angle, showing a faint pale green structural color, consistent with the characteristics of paper in use. (b) is the reflectance spectrum of the thermal photonic paper, which shows a reflectance peak corresponding to the structural color.
[0049] Examples 2-7
[0050] Color control of thermal photonic paper
[0051] In step (1) of Example 1, the particle size of the silica microspheres prepared from 301 nm was replaced with 293 nm, 278 nm, 254 nm, 231 nm, 216 nm, and 198 nm, while other conditions remained the same as in Example 1. By adjusting the particle size of the top-layer template, the color of different top-layer structural colors can be controlled.
[0052] Example 8
[0053] Thermal induction principle of thermal photonic paper
[0054] 1. Template preparation
[0055] A single-layer template was formed by spraying an ethanol dispersion of silica microspheres with a mass fraction of 10% and a particle size of 301 nm onto a glass substrate using a spray gun.
[0056] 2. Preparation of precursor solution
[0057] 1H,1H-perfluorooctyl acrylate and 1,6-hexanediol diacrylate (HDDA) were stirred and mixed evenly at a mass ratio of 1.5%. Photoinitiator 1173, at a mass fraction of 1% relative to the total mass of the mixture, was added and ultrasonically dispersed to ensure uniform mixing. The mixture was then placed in the dark.
[0058] 3. Preparation of single-layer photonic paper
[0059] The uniformly dispersed precursor solution slowly penetrates into the gaps and surface of the monolayer template, initiating polymerization under ultraviolet light to form a composite photonic film. It is then immersed in a 4% hydrofluoric acid solution for 2 hours to etch away the SiO2 template, yielding a monolayer photonic paper.
[0060] 4. Thermally induced monolayer photonic paper
[0061] The prepared single-layer photonic paper was thermally induced at 60°C for 30 seconds.
[0062] Figure 3 (a) is a digital photograph of the single-layer photonic paper described in Example 2. The photograph shows that the obtained photonic paper exhibits a faint pale green structural color. (b) is a digital photograph of the single-layer photonic paper described in Example 2 after thermal induction. The photograph shows that the photonic paper becomes transparent after thermal induction.
[0063] Figure 4 The image shows the change in the reflectance spectrum of the single-layer photonic paper described in Example 2 before and after thermal induction. The spectrum shows that the reflectance peaks of the photonic paper before thermal induction correspond to the color, while the reflectance peaks disappear after thermal induction.
[0064] Figure 5 The image shows the changes in the transmission spectrum of the single-layer photonic paper described in Example 2 before and after thermal induction. The spectrum shows that the photonic paper has low transmittance in the visible light range before thermal induction, while the transmittance is significantly improved after thermal induction.
[0065] Figure 6 This is a SEM image of the single-layer photonic paper described in Example 2 after thermal induction. The image shows that the pores in the thermally induced photonic paper deform and collapse, with no obvious pores on the surface.
[0066] Figure 7 The image shows the DSC curve of the single-layer photonic paper described in Example 2 during the heating process. During the heating process, the phase change polymer exhibited a significant endothermic peak at 52°C, indicating the phase change characteristics of the polymer.
[0067] Examples 9-21
[0068] Temperature regulation of thermal photonic paper
[0069] In step (2) of Example 1, stearate acrylate was replaced with lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate, eicosyl acrylate, dodecyl acrylate, lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, stearate methacrylate, eicosyl methacrylate, dodecyl methacrylate, 1H,1H-perfluorooctyl acrylate, and dodecafluoroheptyl acrylate, while other conditions remained the same as in Example 1.
[0070] Examples 22-23
[0071] Temperature regulation of thermal photonic paper
[0072] In step (2) of Example 1, 1,6-hexanediol diacrylate was replaced with 1,6-hexanediol dimethacrylate and trimethylolpropane trimethacrylate, while other conditions remained the same as in Example 1.
[0073] Example 24
[0074] Thermal photosensitive paper for color printing undergoes thermal induction treatment at 60°C.
[0075] The thermal photonic paper for color printing prepared in Example 1 was thermally induced at 60°C for 30 seconds. Under thermal stimulation, the phase change polymer underwent a crystallization-melting transition, causing the top cavity structure to collapse and become transparent, thus revealing the red structural color of the intermediate color layer.
[0076] Figure 8 This is a structural color photograph of the thermal photonic paper used for color printing described in Example 1 after thermal induction at 60°C. The thermally induced color layer is a structural color layer constructed from high-refractive-index sulfur-containing microspheres, and the quasicrystalline structure assembled at 265nm appears red.
[0077] Example 25
[0078] Thermal printing on thermal photonic paper using a thermal printer
[0079] Thermal printing with high color contrast was performed on the thermal photonic paper prepared in Example 1 using a commercial thermal printer.
[0080] Figure 9 The pattern formed by the thermal photonic paper described in Example 4 on a commercial thermal printer; under thermal stimulation, the phase change polymer undergoes a crystallization-melting transformation, causing the top cavity structure to collapse and become transparent, thereby revealing the red structural color of the middle color layer.
[0081] Examples 26-32
[0082] Color control in color printing
[0083] In step (1) of Example 1, the particle size of the sulfur-containing microspheres prepared was changed from 265 nm to 170 nm, 185 nm, 195 nm, 213 nm, 233 nm, and 248 nm, while other conditions remained the same as in Example 1. By adjusting the particle size of the color development layer template, different colors can be printed.
[0084] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for preparing thermal photonic paper for color printing, characterized in that: The method includes the following steps: (1) Assemble colloidal microspheres of different particle sizes on a glass substrate to form a photonic crystal array or quasi-crystal array, then assemble high refractive index microspheres, and then assemble the colloidal microspheres of the same particle size to construct a three-layer template. (2) The precursor solution of the phase change polymer is filled into the voids of the template and cured by ultraviolet light to obtain a composite structure; (3) After selectively etching away the colloidal microspheres from the composite structure, a cavity-high refractive index microsphere-cavity composite structure is formed, which is then used to form thermal photonic paper.
2. The method for preparing thermal photonic paper for color printing according to claim 1, characterized in that: The precursor solution is a mixture containing a crystalline monomer with double bonds, a crosslinking agent monomer, and a photoinitiator, wherein the mass ratio of the crystalline monomer with double bonds to the crosslinking agent monomer is 100:(1-10), and the photoinitiator is 0.1% to 3% of the total mass of the crystalline monomer with double bonds and the crosslinking agent monomer.
3. The method for preparing thermal photonic paper for color printing according to claim 2, characterized in that: The crystalline monomers with double bonds include one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate, stearate acrylate, eicosyl acrylate, dodecyl acrylate, lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, stearate methacrylate, eicosyl methacrylate, dodecyl methacrylate, 1H,1H-perfluorooctyl acrylate, and dodecafluoroheptyl acrylate.
4. The method for preparing thermal photonic paper for color printing according to claim 2, characterized in that: The crosslinking agent monomer includes one or two of 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, and trimethylolpropane trimethacrylate.
5. The method for preparing thermal photonic paper for color printing according to claim 1, characterized in that: The colloidal microspheres are inorganic colloidal microspheres or polymer colloidal microspheres. The inorganic colloidal microspheres are silica microspheres; the polymer colloidal microspheres are polystyrene colloidal microspheres or polymethyl methacrylate colloidal microspheres; the particle size range of the colloidal microspheres is 100 ~ 400 nm.
6. The method for preparing thermal photonic paper for color printing according to claim 1, characterized in that: The high-refractive-index microspheres are sulfur-containing microspheres, with zinc sulfide, copper oxide, titanium dioxide, and silicon dioxide coating polystyrene microspheres.
7. The method for preparing thermal photonic paper for color printing according to claim 1, characterized in that: The photonic crystal array or quasi-crystal array is assembled from colloidal microspheres. The photonic crystal array is assembled by methods such as heat assembly, dip-coating, vertical deposition, blade coating, or spin coating; the quasi-crystal array is assembled by methods such as drop coating or spray coating.
8. The method for preparing thermal photonic paper for color printing according to claim 1, characterized in that: The methods for selectively etching away colloidal microspheres are calcination or chemical etching.
9. A thermal photosensitive paper for color printing, characterized in that: It is prepared by any one of the methods described in claims 1-8.
10. A thermal photosensitive paper for color printing according to claim 9, characterized in that: Thermosensitive photonic paper has a "sandwich structure" of a thermosensitive layer, a color-developing layer, and a protective layer. The thermosensitive layer and the protective layer are cavity structures composed of phase change polymers with obvious phase change characteristics; the color-developing layer is a photonic crystal array or quasi-crystal array composed of high-refractive-index microspheres.