Puf pattern with flexi-layer structure and method of manufacturing the same

Abstract

This invention belongs to the field of anti-counterfeiting label technology and discloses a PUF pattern with a buckled-layered structure and its preparation method. The invention involves spin-coating PDMS onto a substrate, heating and curing it, and then subjecting it to plasma treatment to obtain a PDMS film. Further, a PVA aqueous solution containing NaB is spin-coated onto the PDMS film, and after drying, ultraviolet crosslinking is performed to obtain a PVA / PDMS bilayer film. Under specific heat treatment conditions, an ethanol aqueous solution is added, and then PDMS is spin-coated again for pattern protection, resulting in a PUF pattern with a buckled-layered structure. This layered structure is a completely autonomous assembly process, possessing the characteristics of uniqueness, randomness, identifiability, physical non-cloning, and strong stability. The preparation method provided by this invention is simple, uses readily available raw materials, and has low cost, making it practically applicable in the anti-counterfeiting field and possessing significant market value.

Description

Technical Field

[0001] This invention relates to the field of anti-counterfeiting label technology, and in particular to a PUF pattern with a buckling layered structure and its preparation method. Background Technology

[0002] Counterfeit goods have a significant impact on economic development. Integrating anti-counterfeiting labels with unique non-cloning features (PUF) into products is a promising solution. Certain patterns generated by surface instability possess PUF properties. On the one hand, these patterns can be manufactured into labels by random processes, becoming "keys"; on the other hand, the patterns generated by instability can be stored, becoming "locks." The combination of these two can achieve robust anti-counterfeiting. Surface instability is a phenomenon in which the internal equilibrium of a system is disrupted under the stimulation of a physical field, leading to changes in surface morphology, such as wrinkles, buckling, and delamination.

[0003] Most existing anti-counterfeiting labels are made using special optical materials, and their production requires high-precision technology and equipment, such as laser confocal imaging and layer-by-layer scanning. However, existing anti-counterfeiting labels also face many problems in material selection and preparation. For example, optical materials are not only expensive but may also have unstable structures, affecting their anti-counterfeiting effectiveness. Furthermore, the preparation process for existing anti-counterfeiting labels is cumbersome, and labels produced using these methods are susceptible to external environmental interference, thus impacting their effectiveness. Therefore, providing a PUF pattern with low production cost, simple process, randomness, identifiability, and good stability, along with its preparation method, is of great significance. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a PUF pattern with a buckling layered structure and a method for preparing the same, thereby resolving the issues raised in the background section.

[0005] This invention provides a method for preparing a PUF pattern with a buckling layered structure, comprising the following steps:

[0006] S1. Spin-coat PDMS onto a substrate, cure it at 80℃-120℃, and then perform surface modification by plasma treatment to obtain a PDMS film.

[0007] S2. Spin-coat a PVA aqueous solution containing NaB onto the PDMS membrane, dry it at 40℃-60℃, and then perform ultraviolet crosslinking to obtain a PVA / PDMS bilayer membrane.

[0008] S3. The PVA / PDMS bilayer film is preheated at 30℃-60℃, then an ethanol aqueous solution is added dropwise, and the film is dried to obtain a primary PUF pattern.

[0009] S4. Spin-coat PDMS onto the primary PUF pattern to obtain the PUF pattern.

[0010] Compared to existing technologies, the PUF pattern provided by this invention is obtained by simply preparing a bilayer film and utilizing droplet-induced surface buckling and delamination instability. After adding an ethanol-water solution to the PVA / PDMS bilayer film, the PVA film in the PVA / PDMS bilayer film swells through water absorption, generating an interfacial stress σ between the two layers. Due to the large modulus of the PDMS film, this stress σ represents the critical stress σ that causes wrinkling instability. c When the stress exceeds the interfacial stress σ between the two layers, wrinkling instability will not occur. However, since the interfacial stress σ cannot be released through wrinkling instability, and the local interfacial stress exceeds the bonding strength between the two layers, the PVA film in the PVA / PDMS bilayer will undergo irreversible delamination to release the interfacial stress. Due to the mismatch in interfacial stress, a PUF pattern with a buckling-layered structure is formed, which has the characteristics of strong stability, uniqueness, identifiability, randomness, and physical non-cloning. Furthermore, this invention can further enhance the stability and heat resistance and water resistance of the PUF pattern by spin-coating PDMS onto the primary PUF pattern. The PUF pattern prepared by the preparation method provided by this invention has a buckling-layered structure. This layered structure is a completely autonomous assembly process, which has the characteristics of uniqueness, randomness, identifiability, physical non-cloning, and strong stability. The preparation method provided by this invention is simple, uses readily available raw materials, and has low cost. It can be practically applied in the field of anti-counterfeiting and has great market value.

[0011] Preferably, in step S1, the substrate is a rigid substrate, which can be glass, polymethyl methacrylate, or polyethylene terephthalate. Before use, it is ultrasonically cleaned and dried with anhydrous ethanol and deionized water. The substrate described in this invention does not have special requirements regarding thickness; it only needs to provide support.

[0012] Preferably, in S1, the curing ratio of the PDMS is (15-30):1.

[0013] It should be explained that the curing ratio refers to the mass ratio of the main agent to the curing agent.

[0014] Preferably, the PDMS main agent in the PDMS is of type C-105, and the curing agent is of type C-105.

[0015] Preferably, in S1, the amount of PDMS used is (0.8g-1.2g) / 9cm. 2 .

[0016] Preferably, in S1, the spin coating rate is 300 rpm to 700 rpm.

[0017] Preferably, in S1, the spin coating time is 30s-90s.

[0018] Preferably, in S1, the curing time is 45s-60s.

[0019] Preferably, in S1, the power of the plasma treatment is 50W-55W.

[0020] Preferably, in S1, the plasma treatment time is 45s-60s.

[0021] By further limiting the power and time of plasma treatment, the hydrophilicity of the PDMS surface can be further enhanced, making it easier for PVA aqueous solution to spread onto the PDMS surface, improving the affinity of the interface, and thus further improving the stability of the PUF pattern.

[0022] Preferably, in S2, the concentration of the PVA aqueous solution is (150mg-250mg) / mL.

[0023] Preferably, in S2, the mass ratio of NaB to PVA in the PVA aqueous solution is (0.02-0.1):1.

[0024] Preferably, in S2, the spin coating rate is 800 rpm to 1200 rpm.

[0025] Preferably, in S2, the spin coating time is 30s-90s.

[0026] Preferably, in S2, the amount of the NaB-containing PVA aqueous solution used is (0.8g-1.2g) / 9cm³. 2 .

[0027] Preferably, in step S2, the drying time is 1-2 hours.

[0028] Preferably, in S2, the conditions for ultraviolet crosslinking are: the wavelength of the ultraviolet light is 254 nm, and the energy density is 5 mW / cm². 2 .

[0029] Preferably, in S2, the ultraviolet crosslinking time is 1.5h-3h.

[0030] Preferably, in S3, the preheating time is 1 min to 2 min.

[0031] Preferably, in S3, the volume ratio of water to ethanol in the ethanol-water solution is 1:9-4:6.

[0032] Preferably, in step S3, the amount of the ethanol-water solution used is (4.8 μL - 5.2 μL) / cm³. 2 .

[0033] By limiting the volume ratio of water to ethanol in the ethanol-water solution and the amount of ethanol-water solution used, a specific interfacial stress difference can be formed between the PVA and PDMS films in the PVA / PDMS bilayer film. This results in a PUF pattern with a distinct buckling and delamination structure, clearly identifiable features, and physical non-cloning characteristics.

[0034] Preferably, in S4, the curing ratio of the PDMS is (15-30):1.

[0035] More preferably, the PDMS main agent in the PDMS is of type C-105, and the curing agent is of type C-105.

[0036] Preferably, in step S4, the amount of PDMS used is (0.8g-1.2g) / 9cm. 2 .

[0037] Preferably, in S4, the spin coating rate is 300 rpm to 700 rpm.

[0038] Preferably, in step S4, the spin coating time is 30s-90s.

[0039] The present invention also provides a PUF pattern with a buckling layered structure, which is prepared by the above-described method for preparing a PUF pattern with a buckling layered structure.

[0040] This invention involves spin-coating PDMS onto a substrate, heating and curing it, and then subjecting it to plasma treatment to obtain a PDMS film. Further, a PVA aqueous solution containing NaB is spin-coated onto the PDMS film, followed by drying and UV crosslinking to obtain a PVA / PDMS bilayer film. Under specific heat treatment conditions, an ethanol aqueous solution is added, and then PDMS is spin-coated again for pattern protection, resulting in a PUF pattern with a buckled, layered structure. This layered structure is a completely autonomous assembly process, possessing uniqueness, randomness, identifiability, physical non-cloning properties, and strong stability. The preparation method provided by this invention is simple, uses readily available raw materials, and has low cost, making it practically applicable in the anti-counterfeiting field and possessing significant market value. Attached Figure Description

[0041] 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.

[0042] Figure 1 Micrograph of a PUF pattern with a buckling layered structure prepared in Example 1 of the present invention;

[0043] Figure 2 Micrograph of a PUF pattern with a buckling layered structure prepared in Example 2 of the present invention;

[0044] Figure 3 Micrograph of a PUF pattern with a buckling layered structure prepared in Example 3 of the present invention;

[0045] Figure 4 The micrograph of the PUF pattern with buckling and layered structure prepared in Example 1 of the present invention after being placed in an oven at 150°C for 2 hours;

[0046] Figure 5 Microscopic images of the PUF pattern with a buckling layered structure prepared in Example 1 of the present invention after being treated with water droplets and immersion.

[0047] Figure 6 A micrograph of the pattern prepared in Comparative Example 1 of this invention;

[0048] Figure 7 This is a micrograph of the pattern prepared in Comparative Example 2 of the present invention;

[0049] Figure 8 This is a micrograph of the pattern prepared in Comparative Example 3 of the present invention. Detailed Implementation

[0050] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1

[0052] This embodiment provides a method for preparing a PUF pattern with a buckling layered structure, comprising the following steps:

[0053] S1. A PDMS mixture with a curing ratio of 15:1 (PDMS main agent type C-105, curing agent type C-105) was spin-coated onto a 1 cm thick substrate at a speed of 300 rpm for 30 s, then cured at 120℃ for 45 s. Surface modification was performed using plasma treatment to obtain a PDMS film. The amount of PDMS used relative to the substrate area was 0.8 g / 9 cm². 2 The plasma treatment power is 50W, and the plasma treatment time is 60s;

[0054] S2. A PVA aqueous solution containing NaB is spin-coated onto the PDMS membrane at a rate of 800 rpm for 90 s, dried at 60°C for 1 h, and then subjected to UV crosslinking for 1.5 h to obtain a PVA / PDMS bilayer membrane; wherein the concentration of the PVA aqueous solution is 250 mg / mL, the mass ratio of NaB to PVA in the PVA aqueous solution is 0.1:1, and the amount of PVA aqueous solution containing NaB relative to the substrate area is 0.8 g / 9 cm². 2 The conditions for ultraviolet crosslinking are: ultraviolet light wavelength of 254 nm and energy density of 5 mW / cm³. 2 ;

[0055] S3. Preheat the PVA / PDMS bilayer film at 60°C for 1 min, then add an ethanol-water solution dropwise, and dry to obtain a primary PUF pattern; wherein the volume ratio of water to ethanol in the ethanol-water solution is 1:9, and the amount of ethanol-water solution relative to the substrate area is 4.8 μL / cm². 2 ;

[0056] S4. Spin-coating PDMS (PDMS base agent type C-105, curing agent type C-105) with a curing ratio of 15:1 onto the primary PUF pattern at a speed of 300 rpm for 90 s to obtain the PUF pattern; wherein, the amount of PDMS relative to the substrate area is 0.8 g / 9 cm². 2 .

[0057] Example 2

[0058] This embodiment provides a method for preparing a PUF pattern with a buckling layered structure, comprising the following steps:

[0059] S1. A PDMS mixture with a curing ratio of 30:1 (PDMS main agent type C-105, curing agent type C-105) was spin-coated onto a 1 cm thick substrate at a speed of 700 rpm for 90 s, then cured at 80 °C for 60 s. Surface modification was performed using plasma treatment to obtain a PDMS film. The amount of PDMS relative to the substrate area was 1.2 g / 9 cm². 2 The plasma treatment power is 55W, and the plasma treatment time is 45s.

[0060] S2. A PVA aqueous solution containing NaB is spin-coated onto the PDMS membrane at a rate of 1200 rpm for 30 s, dried at 40°C for 2 h, and then subjected to UV crosslinking for 3 h to obtain a PVA / PDMS bilayer membrane; wherein the concentration of the PVA aqueous solution is 150 mg / mL, the mass ratio of NaB to PVA in the PVA aqueous solution is 0.02:1, and the amount of PVA aqueous solution containing NaB relative to the substrate area is 1.2 g / 9 cm². 2The conditions for ultraviolet crosslinking are: ultraviolet light wavelength of 254 nm and energy density of 5 mW / cm³. 2 ;

[0061] S3. Preheat the PVA / PDMS bilayer film at 30°C for 2 minutes, then add an ethanol-water solution dropwise, and dry to obtain a primary PUF pattern; wherein the volume ratio of water to ethanol in the ethanol-water solution is 1:4, and the amount of ethanol-water solution relative to the substrate area is 5.2 μL / cm². 2 ;

[0062] S4. Spin-coating PDMS (PDMS base agent type C-105, curing agent type C-105) with a curing ratio of 30:1 onto the primary PUF pattern at a speed of 700 rpm for 30 seconds to obtain the PUF pattern; wherein, the amount of PDMS relative to the substrate area is 1.2 g / 9 cm². 2 .

[0063] Example 3

[0064] This embodiment provides a method for preparing a PUF pattern with a buckling layered structure, comprising the following steps:

[0065] S1. A PDMS mixture with a curing ratio of 20:1 (PDMS main agent type C-105, curing agent type C-105) was spin-coated onto a 1 cm thick substrate at a speed of 500 rpm for 60 s, then cured at 100℃ for 50 s. Surface modification was performed using plasma treatment to obtain a PDMS film. The amount of PDMS used relative to the substrate area was 1 g / 9 cm². 2 The plasma treatment power was 53W, and the plasma treatment time was 50s.

[0066] S2. A PVA aqueous solution containing NaB is spin-coated onto the PDMS membrane at a rate of 1000 rpm for 60 s, dried at 50°C for 1.5 h, and then subjected to UV crosslinking for 2 h to obtain a PVA / PDMS bilayer membrane; wherein the concentration of the PVA aqueous solution is 200 mg / mL, the mass ratio of NaB to PVA in the PVA aqueous solution is 0.06:1, and the amount of PVA aqueous solution containing NaB relative to the substrate area is 1 g / 9 cm². 2 The conditions for ultraviolet crosslinking are: ultraviolet light wavelength of 254 nm and energy density of 5 mW / cm³. 2 ;

[0067] S3. Preheat the PVA / PDMS bilayer film at 50°C for 1.5 min, then add an ethanol-water solution dropwise, and dry to obtain a primary PUF pattern; wherein the volume ratio of water to ethanol in the ethanol-water solution is 1:9, and the amount of ethanol-water solution relative to the substrate area is 5 μL / cm².2 ;

[0068] S4. Spin-coat the primary PUF pattern with PDMS (PDMS base agent type C-105, curing agent type C-105) at a curing ratio of 20:1 at a speed of 400 rpm for 40 seconds to obtain the PUF pattern; wherein, the amount of PDMS relative to the substrate area is 1 g / 9 cm². 2 .

[0069] Comparative Example 1

[0070] This comparative example provides a pattern that differs from Example 1 in that: in S3, the addition of ethanol aqueous solution is replaced by spraying water;

[0071] The other components and preparation process are the same as in Example 1.

[0072] Comparative Example 2

[0073] This comparative example provides a pattern that differs from Example 1 in that: in S3, the volume ratio of water to ethanol in the ethanol-water solution is 6:4.

[0074] The other components and preparation process are the same as in Example 1.

[0075] Comparative Example 3

[0076] This comparative example provides a pattern that differs from Example 1 in that: in S3, the volume ratio of water to ethanol in the ethanol-water solution is 8:2;

[0077] The other components and preparation process are the same as in Example 1.

[0078] Depend on Figure 1-3 It can be seen that the PUF pattern prepared by the method provided by the present invention has a buckling layered structure with obvious bifurcation points and breakpoints, and has obvious identifiability;

[0079] The present invention, by repeating the operations of Example 1, produces PUF patterns and Figure 1 Clearly different, see Figure 4 The image before processing still shows obvious bifurcation points and breakpoints, which proves that the PUF pattern prepared by the method provided by the present invention has uniqueness, randomness and identifiability. After placing it in a 150°C oven for 2 hours, microscopic observation showed that the pattern did not change after heating, which also proves that the PUF pattern prepared by the method provided by the present invention has heat resistance stability.

[0080] Figure 5 The PUF pattern is prepared using the method of Example 1 of this invention. Because the PUF prepared by this method has randomness and identifiability, the prepared pattern and... Figure 1Although different, they also have obvious bifurcation points and breakpoints. After being treated with dripping water and soaking in water for 5 minutes, the pattern did not change, which also proves that the PUF pattern prepared by the method provided in this invention has water resistance stability.

[0081] Depend on Figure 6 It can be seen that when the method of adding ethanol aqueous solution is changed to spraying water, although the prepared pattern also has bifurcation points and breakpoints, there is no obvious buckling and layering structure, and its bifurcation points and breakpoints overlap significantly, making them difficult to identify.

[0082] Depend on Figure 7 and 8 It can be seen that after adjusting the volume ratio of water to ethanol in the ethanol-water solution, the prepared pattern has no obvious buckling and layering structure, and has very few bifurcation points and breakpoints, and the identifiable features are not obvious.

[0083] 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 method for preparing a PUF pattern with a buckling layered structure, characterized in that, Includes the following steps: S1. Spin-coat PDMS onto a substrate, cure it at 80℃-120℃, and then perform surface modification by plasma treatment to obtain a PDMS film. S2. Spin-coat a PVA aqueous solution containing NaB onto the PDMS membrane, dry it at 40℃-60℃, and then perform ultraviolet crosslinking to obtain a PVA / PDMS bilayer membrane. S3. The PVA / PDMS bilayer film is preheated at 30℃-60℃, then an ethanol aqueous solution is added dropwise, and the film is dried to obtain a primary PUF pattern. S4. Spin-coat PDMS onto the primary PUF pattern to obtain the PUF pattern; In S1, the curing ratio of the PDMS is (15-30):1; In S1, the amount of PDMS used is (0.8g-1.2g) / 9cm. 2 ; In S1, the spin coating rate is 300 rpm to 700 rpm; In S1, the spin coating time is 30s-90s; In S1, the curing time is 45s-60s; In S1, the power of the plasma treatment is 50W-55W; In S1, the plasma treatment time is 45s-60s.

2. The method for preparing a PUF pattern with a buckling layered structure as described in claim 1, characterized in that, In S2, the concentration of the PVA aqueous solution is (150 mg - 250 mg) / mL; and / or In S2, the mass ratio of NaB to PVA in the PVA aqueous solution is (0.02-0.1):1; and / or In S2, the spin coating rate is 800 rpm-1200 rpm; and / or In S2, the spin coating time is 30s-90s.

3. The method for preparing a PUF pattern with a buckling layered structure as described in claim 1, characterized in that, In S2, the amount of the NaB-containing PVA aqueous solution used is (0.8g-1.2g) / 9cm. 2 ; and / or In S2, the drying time is 1-2 hours; and / or In S2, the conditions for ultraviolet crosslinking are: the wavelength of the ultraviolet light is 254 nm, and the energy density is 5 mW / cm². 2 ; and / or In S2, the ultraviolet crosslinking time is 1.5h-3h.

4. The method for preparing a PUF pattern with a buckling layered structure as described in claim 1, characterized in that, In S3, the preheating time is 1 min to 2 min.

5. The method for preparing a PUF pattern with a buckling layered structure as described in claim 1, characterized in that, In S3, the volume ratio of water to ethanol in the ethanol-water solution is 1:9-4:6; and / or In S3, the amount of the ethanol-water solution used is (4.8 μL - 5.2 μL) / cm³. 2 .

6. The method for preparing a PUF pattern with a buckling layered structure as described in claim 1, characterized in that, In S4, the curing ratio of the PDMS is (15-30):1; and / or In S4, the amount of PDMS used is (0.8g-1.2g) / 9cm. 2 .

7. The method for preparing a PUF pattern with a buckling layered structure as described in claim 1, characterized in that, In S4, the spin coating rate is 300 rpm-700 rpm; and / or In S4, the spin coating time is 30s-90s.

8. A PUF pattern with a buckling layered structure, characterized in that, It is prepared by the method for preparing a PUF pattern with a buckling layered structure as described in any one of claims 1-7.

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