Preparation method of cellulose nanocrystal iridescent anti-counterfeiting mark

An anti-counterfeit mark and nano-crystallization technology, which is applied in the field of preparation of cellulose nano-crystal iridescent anti-counterfeit marks, can solve problems such as color films that are not practically applied, and achieve the effects of size balance, good stability, and simple and fast preparation process

Inactive Publication Date: 2015-12-30
NANJING FORESTRY UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the patent "a method for rapidly preparing colorful nanocrystalline cellulose film" (CN103172886) and the patent "a cellulose nanocrystal / graphene composite color film and its rapid preparation method" (CN103937032), only vacuum drying and The method of vacuum filtration prepares a colored solid film, and there is no practical application of this colored film

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  • Preparation method of cellulose nanocrystal iridescent anti-counterfeiting mark

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preparation example Construction

[0024] The preparation method of the iridescent anti-counterfeiting label of cellulose nano crystals comprises the following process steps:

[0025] Step 1, prepare nano crystal suspension with microcrystalline cellulose, its method step comprises:

[0026] (1) Weigh 1-10g of microcrystalline cellulose and add it to 50-100ml of 50-65wt% sulfuric acid, and carry out acidic hydrolysis for 30-120min under magnetic stirring at 40-55°C;

[0027] (2) Add deionized water to terminate the above reaction, centrifuge the obtained solution several times and transfer it to a dialysis bag for dialysis for 1 to 2 days to obtain a nanocrystal suspension, which is filtered and stored for later use;

[0028] Step 2, the preparation of iridescent solid film, its method step comprises:

[0029] (1) Take 10-25ml of nanocrystal suspension, conduct ultrasonic treatment at a power of 300-800W for 5-35min, then take 1-10ml of suspension with a plastic dropper and put it into a plastic petri dish;

...

Embodiment 1

[0033] Preparation of nanocrystalline suspension from microcrystalline cellulose: the method steps include (1) Weighing 5g of microcrystalline cellulose and adding it to 80ml of 64wt% sulfuric acid, and performing acidic hydrolysis for 80min under constant temperature water bath at 45°C; (2) Adding deionized water Terminate the above reaction, let the obtained solution stand still, centrifuge at a speed of 5000rpm / m for 10min with a centrifuge, then wash the precipitate, centrifuge again, repeat several times until no obvious precipitate appears, then transfer the solution to a dialysis bag for dialysis for 2 day, filtered and stored for later use, the pH value of the nanocrystal suspension thus obtained was 5.5, and the concentration was 0.8wt%.

[0034] Preparation of colorless and colored solid films: the method steps include (1) take 2.5ml of the above-mentioned nanocrystal suspension with a rubber dropper and put it into a polyethylene petri dish with a diameter of 3.5cm; ...

Embodiment 2

[0036] Preparation of nanocrystalline suspension from microcrystalline cellulose: the method steps include (1) Weighing 5g of microcrystalline cellulose and adding it to 80ml of 64wt% sulfuric acid, and performing acidic hydrolysis for 80min under constant temperature water bath at 45°C; (2) Adding deionized water Terminate the above reaction, let the obtained solution stand still, centrifuge at a speed of 5000rpm / m for 10min with a centrifuge, then wash the precipitate, centrifuge again, repeat several times until no obvious precipitate appears, then transfer the solution to a dialysis bag for dialysis for 2 day, filtered and stored for later use, the pH value of the nanocrystal suspension thus obtained was 5.5, and the concentration was 0.8wt%.

[0037] Preparation of colored solid-state thin film: Measure 20ml of the above-mentioned nanocrystal suspension with a graduated cylinder, ultrasonically treat it in an ice-water bath for 5min (ultrasonic action time 1s, gap 2s, powe...

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Abstract

The invention relates to a preparation method of a cellulose nanocrystal iridescent anti-counterfeiting mark. The preparation method comprises the following processing steps: 1. preparing nanocrystal suspension with microcrystalline cellulose; 2. preparing an iridescent solid thin film; 3. preparing an iridescent anti-counterfeiting mark. The prepared iridescent solid thin film has a cholesteric liquid crystal phase structure and has selective reflectivity toward light waves. The prepared iridescent solid thin film can obtain colorful patterns under a polarizing microscope. The iridescent anti-counterfeiting mark prepared by utilizing the patterns has unduplicatedness and has application value in the package anti-counterfeiting field.

Description

technical field [0001] The invention relates to a method for preparing an iridescent anti-counterfeiting mark of cellulose nano crystals. It belongs to the field of anti-counterfeiting of biomass materials. Background technique [0002] Cellulose is the most abundant natural polymer in nature and an inexhaustible natural renewable resource. Microcrystalline cellulose is a kind of partially depolymerized cellulose, which is a crystalline powder composed of porous particles. In general plant fibers, microcrystalline cellulose accounts for about 73%. [0003] Cellulose nanocrystals prepared by hydrolysis of sulfuric acid will form negatively charged sulfate groups on the surface, and the special anisotropic morphology and surface charge can form lyotropic cholesteric liquid crystals in water. This cholesteric structure will remain in the formed solid film by evaporating water, and show different colors through selective reflection of 200-800nm ​​wavelength. Such colored soli...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J5/18C08L1/04G09F3/02
Inventor 李大纲张亚运
Owner NANJING FORESTRY UNIV
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