CN106340239B - The optical anti-counterfeiting mark and preparation method thereof that silver nano-grain is formed on titanium dioxide single crystalline surface - Google Patents

Abstract

The invention belongs to field of anti-counterfeit technology, specially a kind of silver nano-grain is identified in the optical anti-counterfeiting that titanium dioxide single crystalline surface is formed and preparation method thereof.The present invention first drips to silver nitrate solution on the surface of titanium dioxide single crystalline piece, then with ultraviolet light irradiation a few minutes, titanium dioxide single crystalline piece surface is made to grow upper silver nano-grain；Then it is covered using micron-sized reticle in sample surfaces, monochromatic light exposure silver nano-grain is used simultaneously, since thermoelectron transfer chemically reacts, the plasma resonance peak position of the silver nano-grain of sample surfaces is made to change, to form the pattern for having wavelength selectivity.This pattern can be used to do the other anti-counterfeiting mark of micro/nano level.The method of the present invention is simple and easy and the period is very short, and obtained anti-counterfeiting mark has wavelength selectivity, and high resolution, this is not available for general papery anti-counterfeiting mark.

Description

The optical anti-counterfeiting mark and its system that silver nano-grain is formed on titanium dioxide single crystalline surface Make method

Technical field

The invention belongs to field of anti-counterfeit technology, and in particular to a kind of anti-counterfeiting mark and preparation method thereof.

Technical background

Existing anti-counterfeiting technology in the world is broadly divided into following several:

(1) paper false proof technique

In traditional bank note, there is the paper formula of this country in each state, certain substance or element are participated in paper, is allowed to As the dedicated paper of print paper money for being difficult to copy.Usually, the important raw material of the dedicated paper of currency be cotton fiber with it is high-quality The wood pulp assimilation quotient of amount, does not add any brightening agent, this is the important difference of bank-note paper Yu other plain papers.However, in paper money In the ticket process of circulation, if causing careless through the solution rinsing containing brightening agent, under ultraviolet light, in fact it could happen that fluorescent reflection；Together When, paper money paper hits acid-base material, can also soften, is thinning.

In the manufacturing process of dedicated bank-note paper, following anti-fake handicraft: 1, watermark can also be used；2, safe line, that is, exist Two compete in strength thin metal wires or plastic cord are embedded in paper using handicraft out of the ordinary during papermaking；3, colored fiber and nothing Color fluorescent fiber is in the paper making process by the fiber of white, blue or other gorgeous colors, or is equably added in paper in proportion In slurry, or it is added in paper portions.

The shortcomings that paper false proof technology is exactly the limitation applied, and the field other than paper cannot apply.

(2) ink false proof process

Ink false proof process is broadly divided into following several: 1, colored fluorescent ink, and this kind of ink is seen under popular light is Popular ink color, but shine in ultraviolet light and lower can issue different fluorescence；2, colorless fluorescent ink, the printing figure of this kind of ink Case is invisible under natural light, and just can be seen that issue light and spacious fluorescence under ultraviolet light；3, magnetic ink, ancient times banknote It is mostly used for using magnetic ink as a quantitative detection index machine-readable, also increases and fabricate difficulty；4, photochromatic printing ink, photochromatic printing ink Using a kind of optical variable device out of the ordinary, after being printed as pattern, as the color for the disagreement pattern for inspecting angle can flash transformation. This kind of ink is cheap to be difficult to purchase, exist must anti-fabricate effect；5, anti-copy ink replicates paper money with color copy machine When ticket, the pattern of this kind of ink printing can generate color conversion, cause to run off the tone come and source tone at par is complete Whole disagreement；6, infrared light ink, infrared printing ink printed patterns are under popular light, colored repercussion, but are inspected with infrared light instrument When then achromatization；7, pearl ink, the metallic luster end that light ink printed patterns can flash light and spacious with the disagreement for inspecting angle Or rainbow end.

The anti-fake disadvantage of ink is can not to make the anti-counterfeiting mark of micron, while being easier come anti-fake by fluorescence It is replicated, to lose antiforge function.

(3) false proof process is printed

Printing false proof process is broadly divided into following several:

1, intaglio plate is chased by hand, chases intaglio plate by hand with its complex process, pattern uniqueness, has extremely strong not analog Property and anti-counterfeiting performance, be the general currency printing handicraft and currency security handicraft of countries, the world；2, intaglio printing, gravure is through carving It engraves, pattern line is in groove type, the space of a whole page lower than printing plate, and after dope inks out pattern, ink is attached on paper money paper, Protrude from paper overview.There are the characteristics that three-dimensional sense is strong, have clear presentation, has concave-convex sense with hand touch；3, rainbow prints, pattern Dominant hue or setting are made of the color of disagreement, but the disagreement color on lines or image is in continuity slowly transition, very certainly So；4, it to print, is printed simultaneously using positive back, meets x ray fluoroscopy x banknote, can be appreciated that the pattern at the same position of positive back is right through front and back Connect, form a complete pattern, to by dislocation-free, without stack phenomenon；5, wiring print, same two lines of nominal value decorative pattern be by The phenomenon that two or more colors form, but transition is thoughtful natural, without white and overlapping is leaked between color and color；6, microfilm of characters prints, Using mask-making technology out of the ordinary, text is narrowed down into the degree that naked eyes almost be can't see, is printed on banknote, it need to be by magnifying glass side It can inspect and arrive.

It prints anti-fake manufacturing technology to be easy to be replicated, to be easy to lose antiforge function, while being not easy to print some It is difficult to make anti-counterfeiting mark on article.

Summary of the invention

That the purpose of the present invention is to provide a kind of antifalse effects is good, preparation speed is fast, it is micro- on non-paper article to can be used for Other optical anti-counterfeiting mark of meter level and preparation method thereof.

Optical anti-counterfeiting mark provided by the invention, is specifically made of titanium dioxide single crystalline piece and silver nano-grain, wherein silver The size of nano particle is between 30 nanometers to 150 nanometers.Referring to Fig. 1, shown in 2,3.

The principle of the invention: various sizes of nano particle can resonate the light of different wave length, when a branch of monochromatic light exposure Particle (such as figure Green particle) with this monochromatic photoresonance can be energy transmission to the electronics on surface, and surface electronic obtains energy After the Schottky barrier for overcoming metal semiconductor to detect simultaneously, go in the conduction band of semiconductor, so that silver atoms reform into silver Ion is free to be opened, and the size of Argent grain will change at this time, and the wavelength of resonance will change.

The production method of the optical anti-counterfeiting mark of micron level provided by the invention, the specific steps are as follows:

(1) firstly, by alcohol and silver nitrate solution (1 mol/L) according to 1:0.8-1.2 volume ratio (preferred volume ratio It is uniformly mixed for 1:1)；With liquid-transfering gun absorption 15-30 uL(preferably 20 uL) mixed solution drop in clear clean titanium dioxide Single-chip (crystal orientation: on 110)；Then the monochromatic light exposure sample for being 365 nanometers with wavelength with the ultraviolet lamp of hand-held, about 3-5 After minute, grow to form silver nano-grain on titanium dioxide single crystalline piece surface, as shown in Figure 1；It is observed with scanning electron microscope Sample violet region, as shown in Figure 2.It can be seen that, titanium dioxide single crystalline piece surface grown much from above-mentioned sample pictures Silver nano-grain, since the local surface plasma of these silver nano-grains shakes, so color can be generated；

(2) secondly, sample is placed in the solution that water and ethyl alcohol mix, an optics mask is covered in sample surfaces, There is the anti-counterfeiting mark pattern (including text, figure etc., such as shown in Fig. 4 (a)) prepared as needed on the optics mask, Then monochromatic light exposure is used, monochromatic light light intensity is generally 10-18 milliwatt/every square centimeter, irradiation 4-8 minutes, due to thermoelectron Transfer chemically reacts, and the plasma resonance peak position of the silver nano-grain of sample surfaces is made to change, to form one A pattern for having wavelength selectivity, the pattern can be used as anti-counterfeiting mark, referring to fig. 4 shown in (b).

The grayscale image of anti-counterfeiting mark pattern same position is extracted, it can be seen that the pattern worked it out is relative to light There is certain broadening for mechanical pattern, but its resolution ratio can also reach 1.24 microns, which illustrates that such method is worked it out Pattern can achieve micron-sized resolution ratio.See shown in Fig. 4 (c).

In the present invention, optics mask generally uses ultraviolet photolithographic method to prepare, and can also directly buy.For example the present invention is implemented The pictorial pattern of the monogram and Fudan University's school badge of preparation one " FDU " in example.

In the embodiment of the present invention, it be 30 nanometers of light intensity is that 15 milliwatts are often put down that monochromatic light, which uses 500 nanometers of halfwidths, Square centimetre of monochromatic light.

The pattern made by the method for the present invention is selective for monochromatic light, so, it can be Information hiding in optical wavelength In, to obtain the optical anti-counterfeiting mark of micron level.Fudan University's school badge an of micro-meter scale is made that in the embodiment of the present invention Pattern is (with 500 nanometers of monochromatic light, 14 mW/cm², 5 minutes irradiating samples), the results showed that, ineffective monochromatic light, black and white or coloured silk Form and aspect machine, or observation or reflective observing are projected with microscope, it all can only can just see the thin of pattern clearly under suitable wavelength Section.

Advantages of the present invention is as follows

Firstly, raw materials simply easily obtain: 1, titanium dioxide single crystalline piece (110 crystal orientation)；2, silver nitrate solution；3, light Learn mask (can directly buy, and can reuse, large area mask is needed replacing for large area production)；4, Monochromatic source；

Secondly, this production method is simple and the period is very short, it is only necessary to strictly be operated according to production method, a few minutes can It makes；

Again, the high resolution of this anti-counterfeiting mark, minimum resolution can achieve 1.24 microns, can satisfy the overwhelming majority Anti-fake needs.This anti-counterfeiting mark has the characteristic of optical wavelength selection, this is spy not available for general papery anti-counterfeiting mark Point.

In conclusion quickly easily preparing the present invention provides a kind of, having wavelength selectivity and high-resolution anti-counterfeiting label Know.

Detailed description of the invention

Fig. 1 is to utilize UV light-induced, the sample of the silver nano-grain of growth on titanium dioxide single crystalline piece (crystal orientation 110) surface Product photo.

Fig. 2 is sample in cross section schematic diagram.After irradiating monochromatic light, the size of certain silver nano-grains is changed.

Fig. 3 is the electron scanning micrograph of silver nano-grain.

Fig. 4 is micro-nano-scale anti-counterfeiting mark pattern optics mask (i.e. mask plate) of the invention and passes through monochromatic light exposure The resolution ratio diagram of optical design and pattern afterwards.Wherein, a indicates the optics of the mask plate of the micro-nano-scale of a hollow out Photo；B expression is blocked before sample using its mask plate, then after monochromatic light exposure, the Yin Na that is left on sample The optical design of rice grain composition；C is that the gray value of black dotted lines in figure a (figure c orbicular spot line) is taken out, same in Yu Tu b (black dotted line schemes c intermediate cam point line) gray value taking-up of one position is compared, and the resolution ratio for the pattern made reaches 1.24 micron.

Fig. 5 is covered using the mask plate of the micro-meter scale of Fudan University's school badge of photoetching technique production in sample surfaces, irradiation 500 nanometers of monochromatic light obtain the pattern of Fudan University's school badge, while this pattern is observed under the monochromatic light of different wave length, is obtained The clarity arrived is different.First row is the reflection photo of the image of black and white camera shooting in Fig. 5, and second row is black and white camera bat The transmission photo for the image taken the photograph.

Specific embodiment

The present invention is further described below by specific embodiment (Fudan University's school badge pattern).

1, the photolithography plate of different size of Fudan University's school badge pattern has been designed and produced first, this can pass through relevant business Company's customization.

2, firstly, by alcohol and silver nitrate solution (1 mol/L) according to 1:0.8-1.2 volume ratio (preferred volume ratio It is uniformly mixed for 1:1)；With liquid-transfering gun absorption 15-30 uL(preferably 20 uL) mixed solution drop in clear clean titanium dioxide Single-chip (crystal orientation: on 110)；Then the monochromatic light exposure sample for being 365 nanometers with wavelength with the ultraviolet lamp of hand-held, about 3-5 After minute, grow to form silver nano-grain on titanium dioxide single crystalline piece surface.

3, then the titanium dioxide single crystalline piece of the good silver nano-grain of length is put into surface plate, the inside imports alcohol and water Mixed solution (volume ratio 1:2), the surface for being covered on titanium dioxide single crystalline piece with figuratum photolithography plate made.

4, on the monochromatic light exposure to surface plate after adding 500 nanometers of narrow band filter to filter bromine tungsten filament lamp, light intensity at this time The about 14 every one-storey houses centimetre of milliwatt wait about 5 minutes.

5, sample pattern is observed under the microscope, can be obtained anti-with Fudan University's school badge pattern as show in Figure 5 Puppet mark.

Claims (2)

1. the manufacture method of the optical anti-counterfeiting mark that a silver nanoparticle forms on the surface of titanium dioxide single crystal, it is characterized in that, concrete steps are: (1) First, mix 1 mol/L alcohol and silver nitrate solution uniformly in a volume ratio of 1:0.8-1.2; use a pipette to draw 15-30 uL of the mixed solution and drop it on a clear and clean single-crystal titanium dioxide wafer. Direction: 110; then irradiate the sample with monochromatic light with a wavelength of 365 nanometers for 3-5 minutes with a hand-held ultraviolet lamp, to grow and form silver nanoparticles on the surface of the titanium dioxide single wafer; (2) Then, place the sample in a solution mixed with water and ethanol, cover the surface of the sample with an optical mask, the optical mask has an anti-counterfeiting logo pattern prepared as required, irradiated with monochromatic light, and the intensity of monochromatic light is It is 10-18 mW/cm2, irradiating for 4-8 minutes to form an anti-counterfeiting mark pattern with wavelength selection characteristics. 2 . The manufacturing method according to claim 1 , wherein the size of the silver nanoparticles is between 30 nanometers and 150 nanometers. 3 .