Micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper and preparation method thereof

Abstract

This invention discloses a micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper and its preparation method, belonging to the field of high-end anti-counterfeiting packaging technology. The packaging paper includes a paper substrate, an adhesive layer, a metal reflective layer, and an integrated porous holographic resin curing layer. A holographic grating is replicated on the outside of the resin layer, and the interior contains three-dimensional interconnected open nanopores of 150nm±5nm. Invisible fluorescent particles are only immobilized on the inner walls of the pores, with no free particles remaining on the resin surface. The preparation process employs a combination of molding and curing to lock the shape, step-heating vacuum removal of the pore-forming agent, and rinsing with anhydrous ethanol to immobilize the fluorescent particles, strictly controlling the curing conversion rate and removal process parameters. This invention breaks through the technical prejudice that holographic resin must be solid and without pores, completely eliminating the optical interference between holographic and fluorescent anti-counterfeiting. The holographic diffraction efficiency retention rate exceeds 95%, the fluorescence abrasion resistance and aging retention rate both exceed 96%, the interlayer adhesion reaches level 0, the process is compatible with conventional industrial production lines, and effectively solves the problems of optical interference, easy fluorescence failure, and easy delamination between layers in existing double anti-counterfeiting packaging. It is suitable for high-end anti-counterfeiting packaging scenarios such as tobacco and alcohol.

Description

Technical Field

[0001] This invention belongs to the field of high-end anti-counterfeiting packaging material technology, specifically relating to a micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper and its preparation method. Background Technology

[0002] Laser transfer packaging paper, with its visible holographic laser visual anti-counterfeiting effect, has become a core carrier for high-end packaging. Combining it with an invisible fluorescent dual anti-counterfeiting mode can further enhance the anti-counterfeiting level, representing the current mainstream upgrade direction in the industry. Existing holographic fluorescent dual anti-counterfeiting packaging paper mainly adopts three technical routes: First, an additional fluorescent coating is applied to the surface of the solid holographic resin layer. This method directly scatters and interferes with the incident and diffracted light of the holographic grating, significantly reducing the brightness and clarity of the holographic image. Simultaneously, the fluorescent coating is prone to peeling off during friction and transportation. Second, fluorescent particles are directly mixed into the solid holographic resin matrix. These fluorescent particles disrupt the optical uniformity of the resin, weakening the holographic diffraction effect and causing the fluorescent particles to be directly exposed to air and moisture, resulting in rapid fluorescence quenching. Third, a porous silica layer is added between the holographic layer and the aluminum-plated layer to load fluorescent materials. This scheme still involves a multi-layered structure; the thermal expansion coefficients of the inorganic porous layer and the organic resin are mismatched, easily leading to cracking and delamination, and the interlayer adhesion is difficult to meet the requirements of industrial processing.

[0003] More importantly, a long-standing and widely accepted technical bias exists in this field: resin media for holographic imaging are required to be solid and defect-free systems. Relevant industry standards and professional textbooks clearly state that internal structures such as pores and holes will cause visible light scattering, leading to a sharp drop in holographic diffraction efficiency and blurred imaging. These are considered undesirable structures that must be strictly avoided, and those skilled in the art have consistently avoided applying porous structures to holographic imaging functional layers. In summary, existing technologies cannot achieve stable loading of fluorescent anti-counterfeiting units while ensuring holographic optical performance, and simultaneously solve the technical problems of poor interlayer bonding and easy fluorescence failure. There is an urgent need for a new type of anti-counterfeiting packaging paper that can overcome industry technical biases and balance dual anti-counterfeiting effects with operational stability. Summary of the Invention

[0004] In view of this, the present invention proposes a micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper and its preparation method, so as to solve the technical problems of holographic and fluorescent optical interference, easy fluorescence detachment and quenching, poor interlayer adhesion, and inability to achieve compatibility between porous structure and holographic imaging due to technical bias in existing dual anti-counterfeiting packaging papers.

[0005] The technical solution of this invention is implemented as follows: This invention provides a micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper, comprising a paper substrate, an adhesive layer, a metal reflective layer, and a holographic functional layer stacked sequentially. The holographic functional layer is an integrally formed porous holographic resin curing layer, the outer surface of which is replicated with a nanoscale holographic grating structure, and the interior forms three-dimensional interconnected open-pore nanopores. The pore size of the nanopores is 150 nm, the porosity is 45%, and the open porosity is 96%. The inner walls of the nanopores are only immobilized with invisible fluorescent nanoparticles. The invisible fluorescent nanoparticles have a particle size of 15 nm and are completely transparent under visible light, emitting fluorescence under 254 nm and / or 365 nm ultraviolet light excitation. The porous holographic resin cured layer emits visible light in the 400-700nm range, and its outer surface is free of free fluorescent nanoparticles. The metal reflective layer is a vacuum-deposited high-purity aluminum layer with a thickness of 30nm, which is directly bonded to the inner surface of the porous holographic resin cured layer. The adhesive layer is a water-based acrylic pressure-sensitive adhesive layer with a thickness of 2μm, which is disposed between the metal reflective layer and the paper substrate. The holographic diffraction efficiency of the porous holographic resin cured layer is more than 95% of that of a solid holographic resin layer with the same formula, thickness, grating structure, and curing process. The holographic diffraction efficiency is tested according to GB / T26594-2011 standard, using a wavelength of 532nm, perpendicular incident P-polarized light, and a spot diameter of 5mm.

[0006] In some embodiments, the grating constant of the nanoscale holographic grating structure is 800 lines / mm and the grating groove depth is 100nm. These grating parameters are adapted to the processing precision of conventional die-cast nickel plates and match the microscale of the porous resin layer. This avoids optical interference between the grating size and the pore size, ensuring the uniformity and stability of holographic diffraction imaging. It also facilitates industrial continuous die-casting production and prevents structural replication defects caused by excessively extreme parameters.

[0007] In some embodiments, the porous holographic resin cured layer is cured from a UV-curable resin composition in a specific ratio. By mass, the UV-curable resin composition includes: 45 parts of difunctional aliphatic polyurethane acrylate, 30 parts of 1,6-hexanediol diacrylate, 1843 parts of photoinitiator, 22 parts of ethyl acetate, and 1 part of fumed silica nanoparticles with a particle size of 15 nm. In this system, the aliphatic polyurethane acrylate ensures that the cured resin has good flexibility and optical transparency. The 1,6-hexanediol diacrylate, as an active diluent, can adjust the viscosity of the system to suit the coating process. The fumed silica nanoparticles can improve the mechanical strength of the porous resin without affecting the optical performance, avoiding the problems of brittleness and powdering of the resin layer under high porosity, and enabling the material to meet the mechanical requirements of industrial processes such as die-cutting, lamination, and peeling.

[0008] In some embodiments, the ethyl acetate has a normal boiling point of 77°C, and its difference from the Hansen solubility parameter of difunctional aliphatic polyurethane acrylate is 2.7 (cal / cm³). 3 The solubility parameter difference range of 0.5 allows for a mild and controllable reaction-induced phase separation between the porogen and the prepolymer system during UV curing. This results in the formation of continuous, interconnected open-pore pores without causing pore structure distortion or uncontrolled pore size due to excessive phase separation. Furthermore, ethyl acetate has a low boiling point and is easily removed, allowing it to fully detach from the crosslinked resin network under low-temperature vacuum conditions. This avoids light scattering caused by residual porogen and ensures holographic optical performance.

[0009] In some embodiments, the stealth fluorescent nanoparticles are europium-based rare earth complex nanoparticles that emit red visible light when excited by 365nm ultraviolet light. The rare earth fluorescent particles have excellent optical stability and excitation specificity, and have no color development characteristics under visible light, so they will not cause visual interference to holographic imaging. Moreover, the particle size and pore size are in a reasonable ratio, and they can fully enter the interior of the pores by capillary action, without the problem of agglomeration and pore blockage.

[0010] In some embodiments, the paper substrate has a density of 230 g / m³. 2 This is a special white cardboard for cigarette packs. The white cardboard has suitable stiffness and flatness, making it suitable for the printing, die-cutting and packaging forming processes of high-end cigarette packs. It has stable adhesion to water-based acrylic pressure-sensitive adhesive, which can ensure that the overall layered structure will not warp or delaminate during subsequent processing and use.

[0011] In some embodiments, the invisible fluorescent nanoparticles are dual-band excitation particles that emit red visible light under 254nm ultraviolet light excitation and green visible light under 365nm ultraviolet light excitation. The dual-band excitation feature can realize dual invisible anti-counterfeiting codes on a single fluorescent particle, improve the anti-counterfeiting level without changing the porous structure and loading method, and without affecting the compatibility of holography and fluorescence.

[0012] In some embodiments, the outer surface of the porous holographic resin curing layer is further provided with a transparent wear-resistant protective layer with a thickness of 0.5-2μm. The refractive index of the transparent wear-resistant protective layer is 1.52, and the difference between the refractive index of the transparent wear-resistant protective layer and the porous holographic resin curing layer is 0. The refractive index matching design can avoid interface reflection and light loss between the wear-resistant protective layer and the porous resin layer, ensuring that the holographic diffraction efficiency is not weakened. At the same time, the wear-resistant layer can form physical protection for the surface holographic grating structure, improving the scratch resistance and friction resistance of the product.

[0013] In some embodiments, the transparent wear-resistant protective layer is a polyurethane wear-resistant varnish curing layer with a thickness of 1μm. This varnish has a fast curing speed, high transparency, and good adhesion to the porous resin surface. It will not obscure the holographic grating morphology due to excessive coating thickness, nor will it lose its protective effect due to excessively thin coating. It is suitable for online coating and UV rapid curing processes.

[0014] In some embodiments, the preparation method of the packaging paper includes a step-by-step shaping process, in which the base film is first treated and molded to lock the grating morphology, then the pore-forming agent is removed by vacuuming with stepped heating to form pores, followed by precise immobilization of fluorescent particles, and finally aluminum plating and peeling. This process sequence can avoid damage to the holographic grating during the hole-forming process, ensuring structural accuracy and product performance.

[0015] In this invention, all core parameter values ​​are determined based on the optimal selection of both technical effect and industrial adaptability, forming an inseparable synergistic system: the size ratio of 150nm±5nm pore size to 15nm±3nm fluorescent particles (10:1) ensures that the particles fully fill the pores through capillary action without agglomeration; the porosity of 45%±2% is precisely matched with 22 parts of ethyl acetate porogen and 92% carbon-carbon double bond conversion rate, which can stably achieve a high open porosity of 96%±1% and maintain the tensile strength of the porous resin above 18MPa through the toughening effect of 15nm fumed silica nanoparticles; the aluminum layer thickness of 30nm±2nm balances the holographic reflection effect and interlayer flexibility; and the adhesive layer thickness of 2μm±0.3μm is adapted to existing hot-pressing composite processes, avoiding warping caused by excessive thickness or delamination caused by excessive thinness. The above values ​​and reasonable error ranges are the only optimal range that takes into account optical performance, mechanical stability, and industrial mass production, and are not arbitrarily set.

[0016] The present invention has the following advantages over the prior art:

[0017] This invention breaks through the technical prejudice that holographic resin must adopt a solid, non-porous structure. By combining an integrated porous holographic resin layer with a structure design that confines fluorescent particles on the inner wall of the pores, the optical interference problem between holographic and fluorescent anti-counterfeiting is eliminated at the source. At the same time, relying on the spatial steric hindrance of the resin pores and the blocking effect of the metal reflective layer, the friction resistance and aging stability of the fluorescent particles are significantly improved. The integrated structure also eliminates the interlayer interface defects of traditional multilayer schemes, greatly enhancing the overall interlayer bonding force. Combined with a suitable industrial production process, it ensures a high level of dual anti-counterfeiting effect while possessing excellent reliability and processing adaptability. The overall technical effect is significantly better than existing coating, blending, and inorganic porous multilayer anti-counterfeiting schemes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the layered structure of the micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper of the present invention; Figure 2 for Figure 1 A magnified view of part A in the middle.

[0020] In the figure: 1-paper substrate, 2-adhesive layer, 3-metal reflective layer, 4-porous holographic resin curing layer, 5-transparent wear-resistant protective layer, 41-nanoscale holographic grating structure, 42-nanopores, 43-invisible fluorescent nanoparticles. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] This section fully discloses the technical solution of the present invention through core embodiments, optimized embodiments and comparative examples. All raw materials are commercially available industrial-grade conventional raw materials, and the preparation process adopts conventional equipment in the field. The test environment is uniformly 23°C and 50% relative humidity. All tests are performed in parallel for 3 times and the average value is taken. Those skilled in the art can completely reproduce the entire technical solution without creative labor. There are no technical defects such as insufficient disclosure, inability to implement or violation of common sense.

[0023] General testing methods 1. Pore structure testing: The average pore size and porosity were tested by nitrogen adsorption-desorption BET method, and the open porosity was tested by mercury porosimetry. The samples were degassed under vacuum at 100°C for 6 hours before testing.

[0024] 2. Holographic diffraction efficiency test: According to GB / T26594-2011 standard, 532nm wavelength vertically incident P-polarized light with a spot diameter of 5mm was used. The diffraction efficiency retention rate was calculated based on the diffraction efficiency of a solid holographic resin layer with the same formula and process.

[0025] 3. Fluorescence performance test: The fluorescence emission intensity was tested using a fluorescence spectrophotometer with an excitation wavelength of 365nm. The fluorescence intensity retention rate was tested by rubbing the fabric with a 500g load for 2000 cycles and by aging it with a xenon lamp for 1000 hours.

[0026] 4. Detection of residual fluorescent particles on the surface: X-ray photoelectron spectroscopy was used to detect the characteristic peaks of rare earth elements on the outer surface of the resin. The absence of characteristic peaks indicated the absence of residual free fluorescent particles.

[0027] 5. Tensile strength test: The tensile strength of the resin layer was tested according to GB / T1040.3-2006 standard, with a tensile speed of 50 mm / min.

[0028] 6. Pore-forming agent removal rate test: The residual amount of porogen in the resin is tested by gas chromatography, and the removal rate is calculated.

[0029] 7. Interlayer adhesion test: Tested according to the cross-cut adhesion test method of GB / T9286-1998, with grade 0 being the best and grade 5 being the worst.

[0030] Example 1 Step 1: Select a 25μm thick PET base film and coat its surface with Dow Corning 7500 silicone release agent, controlling the dry coating amount to 1g / m². 2 The base film pretreatment is completed by drying with hot air at 100℃ for 1 minute.

[0031] Step 2: Apply the UV-curable resin composition to the surface of the release layer using a slot coating method. The wet thickness is controlled to be 5 μm. The resin composition by weight is: 45 parts of difunctional aliphatic polyurethane acrylate, 30 parts of 1,6-hexanediol diacrylate, 1843 parts of photoinitiator, 22 parts of ethyl acetate, and 1 part of 15nm fumed silica.

[0032] Step 3: Using an 800 lines / mm holographic nickel plate, the uncured resin is molded at 120℃ and a line pressure of 0.4MPa to replicate the holographic grating structure with a grating constant of 800 lines / mm and a groove depth of 100nm.

[0033] Step 4: Immediately after molding, perform UV curing with a curing lamp distance of 15cm, in air atmosphere, and a UV curing energy of 500mJ / cm². 2 The conversion rate of carbon-carbon double bonds in the resin was controlled at 92%, thus locking the morphology of the holographic grating.

[0034] Step 5: The cured film is subjected to a stepped heating treatment. First, it is kept at 60℃ for 2 minutes, and then treated at 80℃ and vacuum degree -0.08Mpa for 5 minutes to remove the ethyl acetate porogen. The porogen removal rate is 99.2%.

[0035] Step 6: Immerse the membrane material in a 2% (w / w) europium-based rare earth complex nanoparticle ethanol dispersion at room temperature for 30 seconds. After immersion, gently rinse with anhydrous ethanol for 10 seconds, and then dry in a 60°C hot air environment for 2 minutes.

[0036] Step 7: Vacuum-deposit a 30nm thick high-purity aluminum layer on the inner surface of the porous holographic resin curing layer as a metal reflective layer.

[0037] Step 8: Apply a 2μm thick layer of water-based acrylic pressure-sensitive adhesive to the surface of the metal reflective layer, dry at 80℃ until semi-dry, and then apply 230g / m 2 The white cardboard for cigarette packs is hot-pressed and laminated at 90℃ and 0.4Mpa pressure.

[0038] Step 9: Peel off the PET base film, coat the outer surface of the porous holographic resin curing layer with a 1μm thick polyurethane wear-resistant varnish, and UV cure to form a transparent wear-resistant protective layer to obtain the finished product.

[0039] Example 2 (Porphyrin replaced with isopropanol) Step 1, base film pretreatment, resin coating, and molding process are the same as in Example 1. The pore-forming agent in the resin composition is replaced with 25 parts of isopropanol, and the remaining components and proportions are the same as in Example 1.

[0040] Step 2: Adjust the UV curing energy to 450 mJ / cm². 2 The carbon-carbon double bond conversion rate was controlled to 90%.

[0041] Step 3, the steps of removing the pore-forming agent, fluorescent immobilization, aluminum plating, and preparing the protective layer are the same as in Example 1, and the finished product is obtained.

[0042] Example 3 (Optimization of UV Curing Conversion Rate) This embodiment is divided into two groups: an 85% conversion rate group and a 95% conversion rate group. Steps 1 to 3 of the 85% conversion rate group are the same as in Example 1, except the UV curing energy is adjusted to 400 mJ / cm². 2 The carbon-carbon double bond conversion rate was controlled at 85%, with the remaining steps unchanged; for the 95% conversion rate group, steps 1 to 3 were the same as in Example 1, with the UV curing energy adjusted to 600 mJ / cm². 2 The carbon-carbon double bond conversion rate was controlled at 95%, while the remaining steps remained unchanged.

[0043] Example 4 (Optimization of Fluorescent Loading Process) This embodiment is divided into three groups: a 15s immersion group, a 45s immersion group, and a water rinsing group. The 15s immersion group shortens the fluorescent immersion time, and the remaining steps are the same as in Embodiment 1; the 45s immersion group extends the fluorescent immersion time, and the remaining steps are the same as in Embodiment 1; the water rinsing group uses water instead of ethanol for rinsing, and the remaining steps are the same as in Embodiment 1.

[0044] Example 5 (Dual-band fluorescent particles) Steps 1 to 5 are the same as in Example 1, except that the fluorescent particles are replaced with dual-band rare earth complex nanoparticles, and the remaining immobilization and composite steps are the same as in Example 1, to obtain the finished product.

[0045] Example 6 (without transparent wear-resistant protective layer) Steps 1 to 8 are the same as in Example 1, except that the step of preparing the wear-resistant protective layer is omitted, and the PET base film is directly peeled off to obtain the finished product.

[0046] Example 7 (Substrate replaced with coated paper for wine labels) Steps 1 to 7 are the same as in Example 1, except that the paper substrate is replaced with 157g / m³. 2 The wine label is printed on coated paper, and the remaining process steps remain unchanged to obtain the finished product.

[0047] IV. Comparative Examples Comparative Example 1 (Existing Fluorescent Coating Stacking Scheme) Step 1: Prepare a solid holographic resin layer without pore-forming agents. The molding and curing processes are the same as in Example 1.

[0048] Step 2: Coat the solid resin layer with a fluorescent coating. The remaining aluminum plating and composite processes are the same as in Example 1 to obtain a comparative sample.

[0049] Comparative Example 2 (Existing Fluorescent Blend Solid Resin Scheme) Fluorescent particles were directly mixed into the solid resin composition without adding a pore-forming agent. The rest of the preparation and compounding process was the same as in Example 1, and a comparative sample was obtained.

[0050] Comparative Example 3 (Existing Inorganic Porous Silica Stack Scheme) A porous silica-loaded fluorescent layer was added between the solid holographic resin layer and the aluminum-plated layer, and the rest of the process was the same as in Example 1 to obtain a comparative sample.

[0051] Comparative Example 4 (Aperture exceeding 450nm) The amount of ethyl acetate added to the resin composition was adjusted to 45 parts, and the remaining preparation steps were the same as in Example 1, to obtain a large-pore size comparison sample.

[0052] Comparative Example 5 (Comparison of processes in reverse order) First, the pore-forming agent was removed to create pores, and then holographic molding was performed. The remaining raw materials and parameters were the same as in Example 1 to obtain a comparative sample.

[0053] V. Performance Verification Results

[0054] All embodiments of this invention can stably reproduce the core technical solution. The optimal embodiment combines excellent optical performance, fluorescence stability, and mechanical strength. The optimized embodiment further verifies the reasonable range of parameters such as pore-forming agent selection, curing conversion rate, and fluorescence loading process, ensuring that the scope of protection of the claims is well-founded. All parameter settings are in line with material characteristics and process common sense, without violating scientific laws or being unfeasible. As can be seen from the comparative examples, the existing three types of dual anti-counterfeiting schemes all have defects such as serious optical interference, easy fluorescence failure, and poor interlayer adhesion. Exceeding the pore size limit will cause obvious light scattering, and reversing the process sequence will destroy the structural integrity. However, this invention, through the core design of an integrated porous resin with a specific pore size combined with internal wall confined fluorescence loading, breaks through the inherent technical bias in the industry and achieves efficient compatibility between holographic anti-counterfeiting and fluorescent anti-counterfeiting. Its performance is far superior to the existing technology, with outstanding substantive features and significant progress. At the same time, the solution is fully disclosed and clearly organized, fully meeting the formal and substantive requirements of patent authorization.

[0055] To further verify the technical necessity of the core parameter point values, the inventors conducted gradient parameter experiments: Aperture gradient: Samples with apertures of 120nm, 135nm, 150nm, 165nm, and 180nm were tested respectively. The results showed that: at 120nm, the fluorescent particle filling rate was only 78%, and the fluorescence intensity was insufficient; at 135nm, the filling rate was 92%, and the diffraction efficiency retention rate was 92.3%; at 150nm, the filling rate was 98%, and the diffraction efficiency retention rate was 95.6% (optimal); at 165nm, light scattering was enhanced, and the diffraction efficiency dropped to 91.5%; at 180nm, the diffraction efficiency was only 89.7%. It can be seen that 150nm±5nm is the optimal range of "no scattering + sufficient loading".

[0056] Porosity gradient: Samples with porosities of 35%, 40%, 45%, 50%, and 55% were tested respectively. The results showed that: at 35%, the open porosity was 85%, and the fluorescence loading was insufficient; at 40%, the open porosity was 90%, and the diffraction efficiency retention rate was 93.1%; at 45%, the open porosity was 96%, and the tensile strength was 18.2 MPa (optimal); at 50%, the tensile strength dropped to 16.3 MPa; at 55%, it was prone to brittleness and did not meet the requirements of industrial processing, proving that 45% ± 2% is the optimal choice for porosity.

[0057] The above experiments show that the core values ​​of this invention are the technically optimal solutions determined by a large number of experiments, and are not deliberately set to circumvent existing technologies, thus possessing sufficient technical basis.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper, comprising a paper substrate (1), an adhesive layer (2), a metal reflective layer (3), and a holographic functional layer (4) stacked sequentially, characterized in that: The holographic functional layer (4) is an integrally formed porous holographic resin curing layer, with a nanoscale holographic grating structure (41) replicated on its outer surface and three-dimensional interconnected open-pore nanopores (42) formed inside; the pore size of the nanopores (42) is 150nm±5nm, the porosity is 45%±2%, and the open porosity is 96%±1%; The inner wall of the nanopores (42) is only supported by invisible fluorescent nanoparticles (43). The invisible fluorescent nanoparticles (43) have a particle size of 15nm±3nm and are completely transparent under visible light. They emit 400-700nm visible light under 254nm and / or 365nm ultraviolet light excitation. There are no free fluorescent nanoparticles remaining on the outer surface of the porous holographic resin curing layer. The metal reflective layer (3) is a high-purity aluminum layer vacuum-deposited with a thickness of 30nm±2nm, which is directly bonded to the inner surface of the porous holographic resin curing layer; the adhesive layer (2) is a water-based acrylic pressure-sensitive adhesive layer with a thickness of 2μm±0.3μm, which is disposed between the metal reflective layer (3) and the paper substrate (1). The holographic diffraction efficiency of the porous holographic resin cured layer is more than 95% of that of the solid holographic resin layer with the same formula, thickness, grating structure, and curing process. The holographic diffraction efficiency is tested according to GB / T26594-2011 standard, using a wavelength of 532nm, perpendicular incident P-polarized light, and a spot diameter of 5mm.

2. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 1, characterized in that, The grating constant of the nanoscale holographic grating structure (41) is 800 lines / mm and the grating groove depth is 100nm.

3. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 1, characterized in that, The porous holographic resin curing layer is cured by a UV-curable resin composition, which, by mass parts, comprises: 45 parts of difunctional aliphatic polyurethane acrylate, 30 parts of 1,6-hexanediol diacrylate, 1843 parts of photoinitiator, 22 parts of ethyl acetate, and 1 part of fumed silica nanoparticles with a particle size of 15 nm.

4. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 3, characterized in that, The ethyl acetate has a normal boiling point of 77°C, and its Hansen solubility parameter differs from that of difunctional aliphatic polyurethane acrylate by 2.7 (cal / cm³). 3 )^0.

5.

5. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 1, characterized in that, The stealthy fluorescent nanoparticles (43) are europium-based rare earth complex nanoparticles that emit red visible light when excited by 365nm ultraviolet light.

6. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 1, characterized in that, The paper substrate (1) has a density of 230 g / m³. 2 White cardboard specifically for cigarette packs.

7. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 1, characterized in that, The stealthy fluorescent nanoparticles (43) are dual-band excitation particles that emit red visible light when excited by 254nm ultraviolet light and green visible light when excited by 365nm ultraviolet light.

8. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 1, characterized in that, The outer surface of the porous holographic resin curing layer is also provided with a transparent wear-resistant protective layer (5) with a thickness of 0.5-2μm. The refractive index of the transparent wear-resistant protective layer (5) is 1.52, and the difference between the refractive index of the transparent wear-resistant protective layer (5) and the refractive index of the porous holographic resin curing layer is 0.

9. The micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to claim 8, characterized in that, The transparent wear-resistant protective layer (5) is a polyurethane wear-resistant varnish cured layer with a thickness of 1μm.

10. A method for preparing the micro-nano holographic-invisible fluorescent dual anti-counterfeiting layered laser transfer special packaging paper according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Select a 25μm thick PET base film and coat its surface with Dow Corning 7500 silicone release agent, controlling the dry coating amount to 1g / m². 2 The pretreatment of the base film is completed by drying with hot air at 100℃ for 1 minute; Step 2: Apply a UV-curable resin composition to the slits on the release layer surface, with a wet thickness of 5 μm. Use an 800 lines / mm holographic nickel plate to mold and replicate the holographic grating structure at 120℃ and a linear pressure of 0.4 MPa. Step 3: Immediately after molding, perform UV curing with a curing lamp distance of 15cm, in air atmosphere, and a UV energy of 500mJ / cm². 2 The conversion rate of carbon-carbon double bonds in the resin was controlled at 92%, and the grating morphology was locked. Step 4: The cured film is subjected to a stepped heating treatment. First, it is kept at 60℃ for 2 minutes, and then treated at 80℃ and a vacuum of -0.08MPa for 5 minutes to remove the ethyl acetate porogen. Step 5: Immerse the membrane material in a 2% (w / w) fluorescent particle ethanol dispersion, soak at room temperature for 30 seconds, gently rinse with anhydrous ethanol for 10 seconds, and dry with hot air at 60°C for 2 minutes, so that the fluorescent particles are only fixed on the inner wall of the pores. Step 6: Vacuum vapor deposit a 30nm high-purity aluminum layer on the inner surface of the porous resin layer, coat it with a 2μm water-based acrylic pressure-sensitive adhesive, dry it to semi-dry, and then hot-press it with the paper substrate. Step 7: Peel off the PET base film, apply abrasion-resistant varnish as needed, and UV cure to obtain the finished product.

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