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An optical anti-counterfeiting device based on nanocrystalline cellulose

A nanocrystal, optical anti-counterfeiting technology, applied in instruments, identification devices, seals, etc., can solve the problems of rare nanocrystalline cellulose, and achieve the effect of improving timeliness and low cost

Active Publication Date: 2016-09-07
张玉平
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the research on nanocrystalline cellulose began in 1949, it is only in recent years that people are really interested, and the research on optical anti-counterfeiting with nanocrystalline cellulose is still rare.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The preparation process of the optical anti-counterfeiting device based on nanocrystalline cellulose is as follows:

[0030] (1) Raw material pretreatment

[0031] Select the fully bleached Chinese fir cork pulp board, cut it into thin strips of 3×0.5cm, put it into the Willy Mill, grind it through the Willy Mill, and then filter the obtained powder through a 20-mesh sieve to ensure that the wood pulp powder particles uniformity.

[0032] (2) Sulfuric acid hydrolysis

[0033] Take 10g of the pretreated cellulose powder raw material, add 175mL of 64% sulfuric acid to it, stir the reaction, the temperature is 45°C, hydrolyze for 90min, add 10 times deionized water to stop the hydrolysis reaction. Centrifuge the diluted solution at 4500rpm for 15min, remove the clear night from the upper layer of the centrifuge tube, collect the crystal mixture at the root of the centrifuge tube, and dialyze through a 12000-14000 Dalton molecular weight dialysis membrane for 24h until th...

Embodiment 2

[0041] The 5% nanocrystalline cellulose colloid solution obtained in the 25mL embodiment 1 step (2) is processed 5min with the 6mm probe of the Vibera Cell ultrasonic disperser of 130 watts, and the resulting colloid solution is transferred to a petri dish with a diameter of 10cm, at room temperature After standing for 24 hours, a film with a blue base color was obtained.

[0042] Turn the obtained blue film left and right, and the naked eye can see the obvious color change. Put the left-handed circular polarizer and the right-handed circular polarizer on the surface of the film, and you can see the obvious light intensity contrast. The film surface has a strong projection on the left-handed circular polarizer and very weak reflection on the right-handed circular polarizer. Irradiated by ultraviolet light with a wavelength of 345nm, the film does not appear blue when observed in a dark room. Under indoor light conditions, observe with a 10x magnifying glass, and fingerprint p...

Embodiment 3

[0044] The 5% nanocrystalline cellulose colloidal solution obtained in 25mL embodiment 1 step (2) is processed 10min with the 6mm probe of 130 watts Vibera Cell ultrasonic disperser, and the colloidal solution of processing gained is transferred to the petri dish of 10cm diameter, at room temperature After standing for 24 hours, a film with a yellow-brown base color was obtained.

[0045] Turn the obtained yellow-brown film left and right, and the color change from yellow to red can be seen with the naked eye. When the left-handed circular polarizer and the right-handed circular polarizer are placed on the surface of the film, an obvious light intensity contrast can be seen, and the reflection on the film surface can be seen from both the left-handed circular polarizer and the right-handed circular polarizer. Irradiated by ultraviolet light with a wavelength of 345nm, the film does not appear blue when observed in a dark room. Under indoor light conditions, observe with a 10x...

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Abstract

The invention discloses an optical anti-counterfeiting device based on nanocrystalline cellulose, which comprises a nanocrystalline cellulose film pasted on a double-sided adhesive film. Sulfuric acid, stirring at 45°C for 90-120min to acidify and hydrolyze, add 10 times deionized water to terminate the reaction; (2) centrifuge, collect the concentrated suspension at the bottom, and dialyze through a 12000-14000 Dalton molecular weight dialysis membrane to the pH of the solution =7, the suspension after dialysis is ultrasonically dispersed to make a colloidal solution of 0.5wt%-8wt% weight concentration; (3) add fluorescent whitening agent to the colloidal solution, mix well, wherein the concentration of fluorescent whitening agent is 50 -150ppm; (4) place the obtained colloid solution on a polystyrene petri dish and dry at room temperature to obtain a nanocrystalline cellulose film, and paste it on a double-sided adhesive substrate. The optical anti-counterfeiting device of the present invention has multiple and complex explicit and hidden anti-counterfeiting features, can be identified on the spot by simple means, and is not easy to be counterfeited.

Description

technical field [0001] The invention relates to an optical anti-counterfeiting device based on nanocrystalline cellulose, which belongs to the technical field of optics and nanometer materials. Background technique [0002] At present, counterfeit and shoddy goods are rampant, and market fraud continues, which have seriously affected people's lives. The ever-increasing flood of counterfeit and shoddy products urgently calls for new anti-counterfeiting technologies. At present, optical anti-counterfeiting methods in the market include holographic labels, fluorescent inks, and embedded special materials. Among them, holographic products occupy a huge market. The encryption methods it can provide include explicit encryption features, that is, rainbow colors, and implicit encryption features, such as Special fine structure. However, the identification method requires the use of special equipment, which is expensive. And because laser holographic technology has been used for m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G09F3/02C08J5/18C08L1/02
Inventor 张玉平
Owner 张玉平
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