Crystalline-state nanocellulose-based double circularly polarized light/fluorescent thin film material as well as preparation method and application thereof to anti-counterfeiting label

Abstract

The invention provides a crystalline-state nanocellulose-based double circularly polarized light / fluorescent thin film material as well as a preparation method and application thereof to an anti-counterfeiting label and belongs to the technical field of circularly polarized light materials. A full-crystalline-state nanocellulose thin film with a left-handed chiral nematic structure having embeddednematic defects is obtained for the first time by adopting a one-step method through changing two self-assembling conditions including evaporation temperature and initial concentration of a crystalline-state nanocellulose colloidal solution and capturing a metastable-state crystalline-state nanocellulose nematic phase. The nematic defect structure has a half-wavelength retardation effect so thatchiral overturning of circularly polarized light is caused to obtain selectively reflected left-handed and right-handed double circularly polarized light; and a fluorescent object is embedded so as toobtain a double circularly polarized fluorescent signal regulated and controlled by an optical forbidden band in a range from a near ultraviolet waveband to a near infrared waveband. The thin film material can obtain different circularly polarized light patterns through different observation modes so as to realize the application of top-grade anti-counterfeiting labels.

Description

technical field

[0001] The invention belongs to the technical field of circularly polarized light materials, and in particular relates to a crystalline nanocellulose-based double circularly polarized light / fluorescent film material, a preparation method and its application in anti-counterfeiting marks. Background technique

[0002] Cellulose is the natural polymer with the highest storage capacity in nature. Linear polysaccharides formed by D-glucose connected by β-1, 4 glycosidic bonds are mostly distributed in the cell walls of plants, and a few urochordates also contain cellulose in the capsule; in addition, cellulose also exists in in the secretions of some microorganisms. Natural cellulose includes crystalline and non-crystalline regions. The amorphous part of the non-crystalline region can be removed by hydrolysis with sulfuric acid to obtain cellulose in the crystalline region. The size ranges from 5-50nm, so it is called crystalline nanocellulose. Amorphous cellul...

Examples

Embodiment 1

[0055] Example 1: Preparation of crystalline nanocellulose-based dual circularly polarized light / fluorescent film materials under the conditions of 4°C evaporation temperature and 4% initial concentration mass fraction of crystalline nanocellulose colloidal solution:

[0056] (1) Cellulose (cotton pulp cellulose 20g) was stirred with 64% sulfuric acid aqueous solution (220mL) at 45°C for 90min for hydrolysis reaction, then deionized water was used to terminate the reaction, and the obtained solution was poured out after standing The supernatant solution is centrifuged and washed 4 times with deionized water, and the solution is dialyzed to pH=7 with deionized water to obtain a crystalline nanocellulose colloidal solution for use, with a mass fraction of 1-2%.

[0057] (2) Concentrate the crystalline nanocellulose colloidal solution obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, stir for ...

Embodiment 2

[0060] Example 2: Preparation of crystalline nanocellulose-based double circularly polarized light / fluorescence film material under the conditions of 25°C evaporation temperature and 4% initial concentration mass fraction of crystalline nanocellulose colloid:

[0061] (1) The operation is the same as in Embodiment 1.

[0062] (2) Concentrate the crystalline nanocellulose colloidal solution obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, stir for 2 hours, and after forming a uniform and stable solution, pour Put it into a petri dish with a diameter of 3.5 cm, self-assemble at 25° C., and obtain a crystalline nanocellulose bi-circularly polarizing film 2 after the water evaporates.

[0063] Concentrate the colloidal solution of crystalline nanocellulose obtained in step (1) to a mass fraction of 4%, take 35 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained...

Embodiment 3

[0066] Example 3: Preparation of crystalline nanocellulose-based dual circularly polarized light / fluorescent film materials under the conditions of 50°C evaporation temperature and 4% initial concentration of crystalline nanocellulose colloid mass fraction:

[0067] (1) The operation is the same as in Embodiment 1.

[0068] (2) Concentrate the crystalline nanocellulose colloidal solution obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, stir for 2 hours, and after forming a uniform and stable solution, pour Put it into a petri dish with a diameter of 3.5 cm, self-assemble at 50°C, and obtain a crystalline nanocellulose bicircularly polarizing film 3 after the water evaporates.

[0069] Concentrate the colloidal solution of crystalline nanocellulose obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, and ...

technical field

[0001] The invention belongs to the technical field of circularly polarized light materials, and in particular relates to a crystalline nanocellulose-based double circularly polarized light / fluorescent film material, a preparation method and its application in anti-counterfeiting marks. Background technique

[0002] Cellulose is the natural polymer with the highest storage capacity in nature. Linear polysaccharides formed by D-glucose connected by β-1, 4 glycosidic bonds are mostly distributed in the cell walls of plants, and a few urochordates also contain cellulose in the capsule; in addition, cellulose also exists in in the secretions of some microorganisms. Natural cellulose includes crystalline and non-crystalline regions. The amorphous part of the non-crystalline region can be removed by hydrolysis with sulfuric acid to obtain cellulose in the crystalline region. The size ranges from 5-50nm, so it is called crystalline nanocellulose. Amorphous cellul...

Examples

Embodiment 1

[0055] Example 1: Preparation of crystalline nanocellulose-based dual circularly polarized light / fluorescent film materials under the conditions of 4°C evaporation temperature and 4% initial concentration mass fraction of crystalline nanocellulose colloidal solution:

[0056] (1) Cellulose (cotton pulp cellulose 20g) was stirred with 64% sulfuric acid aqueous solution (220mL) at 45°C for 90min for hydrolysis reaction, then deionized water was used to terminate the reaction, and the obtained solution was poured out after standing The supernatant solution is centrifuged and washed 4 times with deionized water, and the solution is dialyzed to pH=7 with deionized water to obtain a crystalline nanocellulose colloidal solution for use, with a mass fraction of 1-2%.

[0057] (2) Concentrate the crystalline nanocellulose colloidal solution obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, stir for ...

Embodiment 2

[0060] Example 2: Preparation of crystalline nanocellulose-based double circularly polarized light / fluorescence film material under the conditions of 25°C evaporation temperature and 4% initial concentration mass fraction of crystalline nanocellulose colloid:

[0061] (1) The operation is the same as in Embodiment 1.

[0062] (2) Concentrate the crystalline nanocellulose colloidal solution obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, stir for 2 hours, and after forming a uniform and stable solution, pour Put it into a petri dish with a diameter of 3.5 cm, self-assemble at 25° C., and obtain a crystalline nanocellulose bi-circularly polarizing film 2 after the water evaporates.

[0063] Concentrate the colloidal solution of crystalline nanocellulose obtained in step (1) to a mass fraction of 4%, take 35 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained...

Embodiment 3

[0066] Example 3: Preparation of crystalline nanocellulose-based dual circularly polarized light / fluorescent film materials under the conditions of 50°C evaporation temperature and 4% initial concentration of crystalline nanocellulose colloid mass fraction:

[0067] (1) The operation is the same as in Embodiment 1.

[0068] (2) Concentrate the crystalline nanocellulose colloidal solution obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, stir for 2 hours, and after forming a uniform and stable solution, pour Put it into a petri dish with a diameter of 3.5 cm, self-assemble at 50°C, and obtain a crystalline nanocellulose bicircularly polarizing film 3 after the water evaporates.

[0069] Concentrate the colloidal solution of crystalline nanocellulose obtained in step (1) to a mass fraction of 4%, take 4 mL of the colloidal solution of the concentrated crystalline nanocellulose obtained, and ...

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