CN109754043B

CN109754043B - Preparation method of micro-nano structure anti-counterfeiting label

Info

Publication number: CN109754043B
Application number: CN201811617691.4A
Authority: CN
Inventors: 李董艳; 顾越; 陈虹宇; 刘优林
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2022-02-22
Anticipated expiration: 2038-12-28
Also published as: CN109754043A

Abstract

The invention relates to a preparation method of a micro-nano structure anti-counterfeiting label, which is obtained by assembling electrostatic spinning fibers and nano particles with a core-shell structure. The nanoparticles contain specific raman molecules with specific raman fingerprint peaks whose intensity and location can be converted into specific barcodes. The material can be stably fixed on the surface of glass, and Raman signals can still keep good after multiple times of washing, so that the material can be used as an anti-counterfeiting label of the glass. The label has special topography, namely micron-sized electrostatic spinning fibers, a nano-sized core-shell structure, a through pore structure, a unique bar code and stable performance.

Description

Preparation method of micro-nano structure anti-counterfeiting label

Technical Field

The invention relates to a preparation method of a micro-nano structure anti-counterfeiting label, belongs to the field of optical materials and anti-counterfeiting thereof, and is particularly suitable for true and false identification of glass substrates.

Background

Automotive glass is an integral part of automotive construction. High-quality glass can withstand wind, rain and gravel, and is a first barrier for guaranteeing life safety. The counterfeit glass not only affects the vision and fatigue degree of the driver, but also poses serious threat to the life of the passengers. The fake and fake glass makes illegal merchants gain violence, but the personal and property rights of consumers are damaged, and the economic development and the image of brand merchants are severely restricted. In order to identify fake and counterfeit products, the order of the whole market is maintained, and the anti-counterfeiting technology is generated. The anti-counterfeiting product prepared according to the anti-counterfeiting technology can identify the authenticity of the substance, which has important research significance in the progress of human beings and the development of society.

The anti-counterfeit labels in the current market are mainly divided into laser labels, inquiry type digital anti-counterfeit labels, texture anti-counterfeit labels and the like from the aspects of technical characteristics and function evolution. For example, a laser-photoetching holographic anti-counterfeiting product is produced by combining a Fuyao group with China telecommunications, and anti-counterfeiting marks are completely stuck to accessories produced by the Fuyao group since 2008. The inquiry type digital anti-counterfeiting label records the product confidence into a database and inquires in an inquiry center or an information base through a telephone or a network. The texture label is an anti-counterfeiting technology which takes speckle marks on the material as anti-counterfeiting identification marks. The stripes in the nature are all very different, for example, the textures of fingerprints, zebra stripes and the like are random and unique, two identical textures are not possible, and the information of the textures is inquired and identified. The anti-counterfeiting product needs to meet the requirements of identity uniqueness, good stability, high safety and the like.

Spectrogram anti-counterfeiting is an important anti-counterfeiting way. Common spectra comprise a fluorescence spectrum and a Raman spectrum, and the fluorescence spectrum has the characteristics of wide emission spectrum, poor color controllability, certain overlapping of spectrograms with different colors, poor bleaching resistance and the like, so that the fluorescence spectrum is limited in anti-counterfeiting. The raman spectrum belongs to a molecular vibration spectrum and can reflect the characteristic structure of molecules, but raman scattering is a very weak process, so that signals are very weak, a certain enhancement effect is basically utilized for the raman spectrum research of surface-adsorbed raman molecules, and Surface Enhanced Raman Scattering (SERS) is an important one of the raman spectrum. Common substrates for surface enhanced raman scattering are gold, silver, copper, and the like. With the continuous development of nanotechnology and nanoscience, nanomaterials in various shapes such as nanoparticles, nanorods, nanowires, nanotubes, and the like are coming out. Due to the small size and large surface energy of the nano-materials, aggregation or fusion can easily occur between particles. When the particles are aggregated or fused, the signals of the raman molecules on the surfaces of the particles are relatively unstable. If the gold and silver nanoparticles are used as the adsorption carriers of Raman molecules, the phenomenon can be effectively avoided by coating the gold and silver nanoparticles. Although the coated nanoparticles can be stored in solution for a certain period of time, they are not conducive to long-term storage and inconvenient to use, and are not conducive to being used as physical labels.

Disclosure of Invention

The invention aims to provide a preparation method of a micro-nano structure anti-counterfeiting label for improving the defects of the prior art.

The technical scheme of the invention is as follows: the material prepared by the inventionThe material combines the pore structure of the electrostatic spinning fiber, the core-shell structure of the nano particles and Raman spectrum, converts the signal of Raman molecules into bar codes, and uses the bar codes as a novel optical anti-counterfeiting label. Firstly, modifying a Raman molecule on the surface of Au NPs; then, coating Au NPs by a sol-gel method to obtain Au @ SiO₂And (4) NPs. The Raman molecules and the Au NPs can react through Au-S bonds, and considering that the Raman molecules have adsorption and desorption states on the surface of the Au NPs at the same time, the silicon dioxide is coated on the surface of the Au NPs, so that the Raman molecules stably exist on the surface of the Au NPs. Meanwhile, the Au NPs are coated by the silicon dioxide, so that the aggregation and fusion of the Au NPs can be effectively avoided. The material takes electrostatic spinning fiber as a carrier, and Au @ SiO is added₂NPs are uniformly dispersed on the surface of the fiber, and Au @ SiO is heated₂The NPs are partially embedded in the fiber to obtain a novel material. The material has a novel micro-nano structure, special pores and stable surface Raman enhancement signals, is converted into a unique bar code, and can be used as an optical anti-counterfeiting label.

The specific technical scheme of the invention is as follows: a preparation method of a micro-nano structure anti-counterfeiting label comprises the following specific steps:

(1) respectively adding a hydrophobic polymer and a hydrophilic polymer into corresponding solvents, stirring to dissolve the hydrophobic polymer and the hydrophilic polymer, and mixing the two solutions in proportion to obtain a polymer spinning solution; optimizing the injection speed, the receiving distance and the voltage parameters of the electrostatic spinning machine to obtain fibers with uniform diameter distribution;

(2) modifying Raman molecules on the surface of gold nanoparticles Au NPs, and coating silicon dioxide on the surface of the Au NPs by a sol-gel method to obtain silicon dioxide coated gold nanoparticles Au @ SiO with a core-shell structure₂NPs；

(3) Au @ SiO obtained in the step (2)₂NPs are dispersed in mixed solution of acetic acid and ammonium acetate, and then the electrostatic spinning fiber is immersed in the above-mentioned solution, so that the electrostatic spinning fiber and Au @ SiO₂Assembling the NPs by using Au @ SiO₂NPs are uniformly and dispersedly adsorbed on the surface of the fiber;

(4) step (3) adsorbsAu@SiO₂The fibers of NPs were laid flat on the surface of a support and then placed in an oven with Au @ SiO₂And embedding NPs into the fibers to obtain the rugged micro-nano structure anti-counterfeiting label.

Preferably, the hydrophobic polymer in step (1) is polymethyl methacrylate (PMMA); the hydrophilic polymer is poly 4-vinylpyridine (P4 VP); the mass concentration of the polymer spinning solution hydrophobic polymer and the mass concentration of the hydrophilic polymer are both 12-38%; the hydrophobic polymer and the hydrophilic polymer are mixed in a mass ratio of 0.5 to 2.

Preferably, the solvent in step (1) is N, N-Dimethylformamide (DMF) and acetone in a volume ratio of 0.25-3: 1 in the ratio of 1.

Preferably, the injection speed of the electrostatic spinning machine in the step (1) is 0.05-0.5 mm/min; the receiving distance is 10-30 cm; the positive pressure is 8-25 kV; the negative pressure is-5 to-1 kV.

Preferably, the particle size of the Au NPs in the step (2) is 40-80 nm; the Raman molecule is one or the mixture of two of mercaptobenzoic acid (4-MBA) and 2-mercaptobenzimidazole-5-carboxylic acid (MBIA), the concentration of the two is 0.01mM-10mM, and the volume ratio of the two mixed concentrations is 0.1-10. The solvent used in the sol-gel method in the step (2) is a mixed solvent of water and isopropanol, the volume ratio of the water to the isopropanol is 0.2-5, and Au @ SiO₂The particle size of the NPs is 50-200 nm; the coating thickness is 10-70 nm.

Preferably, the pH value of the mixed solution of acetic acid and ammonium acetate in the step (3) is 2-10; au @ SiO₂NPs are dispersed in a mixed solution of acetic acid and ammonium acetate at a concentration of 200. mu. mol/L to 200 pmol/L.

Preferably, the electrospun fiber is contacted with Au @ SiO in step (3)₂NPs assembly employs one or both of static, oscillating, or swirling to control assembly speed and dispersion. Preferably, the heating temperature of the oven in the step (4) is 60-200 ℃.

Has the advantages that:

according to the method, micron-sized electrostatic spinning fibers and core-shell structure nanoparticles are assembled, and the nanoparticles are embedded into the electrostatic spinning fibers. The preparation method has the advantages of simple process, abundant and easily-obtained raw materials, novel structure, stable Raman signal, and conversion of intensity and position of fingerprint peak into bar code, and can be used as a novel anti-counterfeit label. The label can stably exist on the surface of a glass carrier, surface Raman enhanced signals can be obtained on the front side and the back side of the glass carrier, and the label has the advantages of high safety coefficient, identity identifiability and the like.

Drawings

FIG. 1 is a scanning electron microscope image of the anti-counterfeit label with the micro-nano structure in the embodiment 4;

FIG. 2 shows the Raman spectrum of the security label and the bar code converted from the same in example 4.

Detailed Description

Example 1

(1) Preparing 12 wt% of PMMA and P4VP spinning solution, wherein the mass ratio of the two polymers is 1:2, the solvent is a mixed solvent of acetone and DMF, and the volume ratio is 2: 1. The parameters for setting the electrospinning machine were as follows: the positive pressure is 25kV, the negative pressure is-5 kV, the pushing speed is 0.20mm/min, and the receiving distance is 20 cm.

(2) Preparing Au NPs with the particle size of about 40nm, modifying 0.01mM 4-MBA on the surface of the Au NPs, and coating silicon dioxide on the surface of the Au NPs by a sol-gel method, wherein the volume ratio of water to isopropanol is 1:5 to obtain Au @ SiO with the particle size of about 60nm₂NPs, with a cladding thickness of about 10 nm.

(3) Au @ SiO solution at a concentration of 200. mu. mol/L₂Dispersing NPs in mixed solution of acetic acid and ammonium acetate with pH of 2, soaking 2cm × 2cm electrospun fiber in the above solution, and keeping the process at rest for 10min to allow the electrospun fiber to contact with Au @ SiO₂And assembling the NPs. Finally, Au @ SiO is adsorbed₂The fibers of NPs are removed from the solution.

(4) Adsorbing Au @ SiO₂And (3) spreading fibers of the NPs on a glass carrier, and heating at the temperature of 60 ℃ to obtain the flexible anti-counterfeiting label.

(5) Raman testing: the 4-MBA Raman spectrogram can be obtained by placing the label in a Raman spectrometer for testing. The 4-MBA fingerprint peak is converted into a bar code, the position and the peak intensity of the peak respectively correspond to the position and the width of a black line of the bar code, the middle space is a white space, and the white space is recorded into a database and further used as an anti-counterfeiting label of materials such as glass.

Example 2

(1) Preparing 20 wt% of PMMA and P4VP spinning solution, wherein the mass ratio of the two polymers is 2:1, the solvent is a mixed solvent of acetone and DMF, and the volume ratio is 1: 3. The parameters for setting the electrospinning machine were as follows: the positive pressure is 18kV, the negative pressure is-1 kV, the injection speed is 0.45mm/min, and the receiving distance is 15 cm.

(2) Preparing Au NPs with the particle size of about 60nm, modifying 8.9mM MBIA on the surface of the Au NPs, and coating silicon dioxide on the surface of the Au NPs by a sol-gel method, wherein the volume ratio of water to isopropanol is 2.5:1 to obtain Au @ SiO with the particle size of about 100nm₂NPs, with a cladding thickness of about 20 nm.

(3) Au @ SiO solution at a concentration of 200pmol/L₂Dispersing NPs in mixed solution of acetic acid and ammonium acetate with pH of 4, soaking 2cm × 2cm electrospun fiber in the above solution, and maintaining oscillation state for 10min to allow the electrospun fiber to contact with Au @ SiO₂And assembling the NPs. Finally, Au @ SiO is adsorbed₂The fibers of NPs are removed from the solution.

(4) Adsorbing Au @ SiO₂And (3) spreading fibers of the NPs on a glass carrier, and heating at 90 ℃ to obtain the flexible anti-counterfeiting label.

(5) Raman testing: the MBIA Raman spectrogram can be obtained by placing the label on a Raman spectrometer for testing. Converting the MBIA fingerprint peak into a bar code, wherein the peak position and the peak intensity respectively correspond to the position and the width of a black line of the bar code, the middle space is a white blank space, and the white blank space is recorded into a database to be used as an anti-counterfeiting label of materials such as glass.

Example 3

(1) Preparing 38 wt% of PMMA and P4VP spinning solution, wherein the mass ratio of the two polymers is 1:2, the solvent is a mixed solvent of acetone and DMF, and the volume ratio is 4: 1. The parameters for setting the electrospinning machine were as follows: the positive pressure is 15kV, the negative pressure is-1 kV, the pushing speed is 0.25mm/min, and the receiving distance is 30 cm.

(2) Preparing Au NPs with the particle size of about 80nm, mixing 5mM 4-MBA and 5mM MBIA (volume ratio of 1:10) to modify the surface of the Au NPs, coating silicon dioxide on the surface of the Au NPs by a sol-gel method, wherein the volume ratio of water to isopropanol is 5:1, and obtaining Au @ SiO with the particle size of about 200nm₂NPs, coating thicknessAbout 60 nm.

(3) The concentration was 1pmol/LAu @ SiO₂Dispersing NPs in mixed solution of acetic acid and ammonium acetate with pH of 9, soaking 2cm × 2cm electrospun fiber in the above solution, and maintaining vortex state for 10min to allow the electrospun fiber to contact with Au @ SiO₂And assembling the NPs. Finally, Au @ SiO is adsorbed₂The fibers of NPs are removed from the solution.

(4) Adsorbing Au @ SiO₂And (3) spreading fibers of the NPs on a glass carrier, and heating at 120 ℃ to obtain the flexible anti-counterfeiting label.

Example 4

(1) Preparing 26.5 wt% of PMMA and P4VP spinning solution, wherein the mass ratio of the two polymers is 2:1, the solvent is a mixed solvent of acetone and DMF, and the volume ratio is 1: 1. The parameters for setting the electrospinning machine were as follows: the positive pressure is 15kV, the negative pressure is-2 kV, the pushing speed is 0.05mm/min, and the receiving distance is 10 cm.

(2) Preparing Au NPs with the particle size of about 60nm, mixing 4.5mM of 4-MBA and 4.5mM of MBIA (volume ratio of 1:1) to modify the surface of the Au NPs, coating silicon dioxide on the surface of the Au NPs by a sol-gel method, wherein the volume ratio of water to isopropanol is 1:2, and obtaining Au @ SiO with the particle size of about 130nm₂NPs, with a cladding thickness of about 35 nm.

(3) The concentration was 150pmol/LAu @ SiO₂Dispersing NPs in mixed solution of acetic acid and ammonium acetate with pH of 6, soaking 2cm × 2cm electrospun fiber in the solution, and maintaining oscillation state for 10min to allow the electrospun fiber to contact with Au @ SiO₂And assembling the NPs. Finally, Au @ SiO is adsorbed₂The fibers of NPs are removed from the solution.

(4) Adsorbing Au @ SiO₂The fibers of the NPs are spread on a glass carrier and heated at the temperature of 150 ℃ to obtain the flexible anti-counterfeiting labelFig. 1 shows a scanning electron microscope image of the anti-counterfeit label with a concave-convex structure.

(5) Raman testing: the MBIA Raman spectrogram can be obtained by placing the label on a Raman spectrometer for testing (as shown in figure 2 a). Converting the MBIA fingerprint peak into a bar code (as shown in figure 2 b), wherein the peak position and the peak intensity respectively correspond to the position and the width of a black line of the bar code, the middle space is a white blank space, and the white blank space is recorded into a database to be used as an anti-counterfeiting label of materials such as glass.

Claims

1. a preparation method of micro-nano structure anti-counterfeiting label, its concrete steps are as follows:

(1) Add the hydrophobic polymer and the hydrophilic polymer into the corresponding solvent and stir to dissolve them, and mix the two solutions in proportion to obtain the polymer spinning solution; optimize the bolus injection of the electrospinning machine speed, receiving distance, and voltage parameters to obtain fibers with uniform diameter distribution; wherein the hydrophobic polymer is polymethyl methacrylate, and the hydrophilic polymer is poly-4-vinylpyridine; the hydrophobic polymer of the polymer spinning solution and the The mass concentration of the hydrophilic polymer is 12%-38%; the hydrophobic polymer and the hydrophilic polymer are mixed according to the mass ratio of 0.5-2; the injection speed of the electrospinning machine is 0.05-0.45mm/min; The receiving distance is 10-30cm; the positive pressure is 15-25kV; the negative pressure is -5 to -1kV;

(2) Raman molecules were modified on the surface of gold nanoparticles Au NPs, and silica was coated on the surface of gold nanoparticles Au NPs by sol-gel method to obtain silica-coated gold nanoparticles Au with core-shell structure @SiO ₂ NPs;

(3) Disperse the silica-coated gold nanoparticles Au@SiO ₂ NPs obtained in step (2) in a mixed solution of acetic acid and ammonium acetate, and then immerse the electrospinning fibers into the above solution to make electrospinning The fibers were assembled with silica-coated gold nanoparticles Au@SiO ₂ NPs, and the silica-coated gold nanoparticles Au@SiO ₂ NPs were evenly dispersed and adsorbed on the fiber surface;

(4) The fibers adsorbed on the silica-coated gold nanoparticles Au@SiO ₂ NPs in step (3) were spread on the surface of the carrier, and then placed in an oven to make the silica-coated gold nanoparticles Au@SiO ₂ The NPs were embedded in the fiber to obtain the anti-counterfeiting label with uneven micro-nano structure.

2. preparation method according to claim 1 is characterized in that the solvent described in the step (1) is the solvent that N,N-dimethylformamide and acetone are mixed in the ratio of 0.25-3:1 by volume ratio .

3. The preparation method according to claim 1, characterized in that in step (2), the particle size of gold nanoparticles Au NPs is 40-80 nm; in step (2), silica-coated gold nanoparticles Au@SiO ₂ The particle size of NPs is 60-200nm; the coating thickness is 10-60nm.

4. preparation method according to claim 1 is characterized in that in step (3), the pH value of acetic acid and ammonium acetate mixed solution is 2-9; Silica-coated gold nanoparticles Au@SiO ₂ NPs are dispersed in acetic acid The concentration in the mixed solution with ammonium acetate is 200μmol/L-200pmol/L.

5. The preparation method according to claim 1, characterized in that in step (3), the electrospinning fibers and the silica-coated gold nanoparticles Au@SiO ₂ NPs are assembled using one of static, vibration or vortex. One or both controls the speed of assembly and the degree of dispersion.

6 . The preparation method according to claim 1 , wherein the heating temperature of the oven in step (4) is 60° C.-150° C. 7 .