CN112391086A

CN112391086A - Fluorescent ink based on carbon quantum dots and preparation method and application thereof

Info

Publication number: CN112391086A
Application number: CN202011185652.9A
Authority: CN
Inventors: 唐瑜; 覃月敏
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2020-10-29
Filing date: 2020-10-29
Publication date: 2021-02-23

Abstract

The invention discloses fluorescent ink based on carbon quantum dots, and a preparation method and application thereof. The fluorescent ink well maintains the excitation wavelength dependence and the concentration dependence of the carbon quantum dots, does not generate quenching of fluorescence after the gloss oil is added, provides possibility for practical industrial application, and has the advantages of simple synthesis method, environmental protection and good application prospect.

Description

Fluorescent ink based on carbon quantum dots and preparation method and application thereof

Technical Field

The invention relates to fluorescent ink based on carbon quantum dots, and a preparation method and application thereof.

Background

The photosensitive anti-counterfeiting ink is an important component of the anti-counterfeiting ink, and refers to fluorescent ink capable of emitting visible light under the illumination condition, and the existing fluorescent ink mainly comprises ultraviolet fluorescent ink and infrared fluorescent ink, which respectively refer to fluorescent ink capable of presenting macroscopic fluorescence under the excitation of long ultraviolet lamps, medium or short waves and fluorescent ink capable of presenting bright fluorescence under the illumination of infrared light with specific wavelength (980nm or 808 nm). Fluorescent ink excited by an ultraviolet lamp is widely concerned due to the advantages of simple detection equipment, good concealment, bright color, low cost and the like. At present, fluorescent anti-counterfeiting ink with red light, blue light and green light is mainly available on the market, and the ink emitting green fluorescence is less in proportion, so that the anti-counterfeiting uniqueness is more prominent. Although the fluorescent anti-counterfeiting ink on the market has various varieties, the fluorescent anti-counterfeiting ink has the defects of low anti-counterfeiting degree, complex process and the like due to single luminescent color and relatively complex preparation process of a plurality of products, so that the research and development of the fluorescent anti-counterfeiting ink with multiple anti-counterfeiting capability and simple preparation process become urgent. In recent years, carbon quantum dots, as a novel carbon nanomaterial, have the characteristics of high fluorescence intensity, good light resistance, high quantum yield and the like, good biocompatibility, low toxicity, low cost and simple preparation, and thus have attracted extensive attention of researchers. Chinese patent CN 109054827A introduces a carbon quantum dot with a high-stability novel structure and a preparation method thereof, a nitrogen source is taken to be mixed with a carbon source, the mixture is put into deionized water to be fully stirred, the stirred mixed solution is put into an ultrasonic device in a reaction kettle under the protection of nitrogen to be subjected to ultrasonic dispersion treatment, and the carbon quantum dot with nitrogen doping and special space effect is prepared in a reaction container by one-time reaction.

Disclosure of Invention

The invention aims to provide a brand-new fluorescent anti-counterfeiting ink with high anti-counterfeiting degree aiming at the defects of the anti-counterfeiting technology. The fluorescent ink takes carbon quantum dots as fluorescent materials, and has concentration dependence, excitation wavelength dependence and different fluorescent lifetimes at different concentrations.

In a first aspect, the invention provides a fluorescent ink based on carbon quantum dots, which comprises carbon quantum dots and gloss oil, wherein the gloss oil comprises an organic solvent, a high molecular resin and an auxiliary agent.

According to a preferred embodiment of the present invention, the gloss oil comprises 50 to 75 parts by weight of an organic solvent, 25 to 35 parts by weight of a polymer resin, and 0.2 to 2 parts by weight of an auxiliary. According to some embodiments, the gloss oil is composed of 50 to 75 parts by weight of an organic solvent, 25 to 35 parts by weight of a polymer resin, and 0.2 to 2 parts by weight of an auxiliary.

According to a preferred embodiment of the present invention, the organic solvent is selected from one or more of ethanol, propanol and n-butanol. According to some embodiments, the organic solvent consists of 30-40 parts by weight of ethanol and 30-40 parts by weight of n-butanol.

According to a preferred embodiment of the present invention, the polymer resin is one or more of polyamide resin, polyurethane resin, ketone-aldehyde resin and acrylic resin.

According to a preferred embodiment of the present invention, the auxiliary agent is one or more of a drier, a viscosity reducer, a plasticizer, a defoamer, an antioxidant and a surfactant.

According to an embodiment of the present invention, the carbon quantum dots are carbon quantum dots having an excitation wavelength dependency (i.e., an emission peak of the carbon quantum dots is red-shifted with an increase in excitation wavelength) and a concentration dependency (i.e., the carbon quantum dots emit blue fluorescence visible to the naked eye under ultraviolet long-wave irradiation at a lower concentration and green fluorescence at a higher concentration).

According to an embodiment of the present invention, the carbon source comprises one or more of citric acid, salicylic acid and malic acid; the nitrogen source is one or more of urea, oxamide, ammonia water and ammonium bicarbonate.

According to some preferred embodiments, the carbon source is citric acid and the nitrogen source is urea.

According to an embodiment of the present invention, the mass ratio of the carbon source to the nitrogen source is preferably 1:2 to 2:1, more preferably 1:1.2 to 1.2: 1.

According to some embodiments of the invention, the ratio of the mass of the carbon quantum dots to the volume of the varnish is 5-35 μ g/mL, preferably 10-30 μ g/mL, and in this concentration range, the fluorescent ink can emit blue fluorescence visible to the naked eye under 365nm ultraviolet irradiation.

According to other embodiments of the present invention, the ratio of the mass of the carbon quantum dots to the volume of the gloss oil is greater than 40 μ g/mL, preferably 60-1000 μ g/mL, more preferably 100-600 μ g/mL, such as 350-400 μ g/mL. In the concentration range, the fluorescent ink can emit green fluorescence visible to the naked eye under 365nm ultraviolet irradiation.

In a second aspect, the present invention provides a method for preparing the fluorescent ink of the first aspect, comprising the steps of:

(1) mixing an organic solvent, high-molecular resin, an auxiliary agent and a grinding aid, oscillating under a closed condition, preferably oscillating for 30-200 minutes, and then removing the grinding aid to obtain a solution which is gloss oil;

(2) mixing the gloss oil and the carbon quantum dots under an ultrasonic condition, wherein the ultrasonic time is preferably 20-50 minutes;

according to some embodiments of the invention, the grinding aid is selected from one or more of glass beads, metal balls, and quartz sand.

According to some embodiments of the present invention, the preparation of the carbon quantum dots comprises heating an aqueous solution of a carbon source and a nitrogen source under microwave conditions, preferably at 600-.

According to some embodiments of the method of manufacturing of the present invention, the method of manufacturing comprises step 1: adding a carbon source, preferably citric acid, and a nitrogen source, preferably urea, in a certain mass ratio into a beaker, then adding 7-15mL of high-purity water, stirring and dissolving to obtain a transparent solution, putting the beaker into a 750W microwave oven, adjusting to a middle level or a middle-high level, heating for 5-15min, obtaining a carbonized black solid matter after the reaction is finished, transferring the black solid matter into an oven after slight cooling, adjusting to 60-70 ℃ and drying for 1-2h so as to remove unreacted micromolecules, then taking out, adding 10-20mL of high-purity water, slowly stirring and dissolving the black solid matter, putting the dissolved solid matter into a high-speed centrifuge (13000 and 15000r/min), centrifuging for 20-30min, filtering a supernatant by using a filter membrane with the aperture of 0.45 mu m, and obtaining a brownish black carbon quantum dot after freeze-drying;

step 2: mixing the polymer resin, the organic solvent, the grinding aid and the auxiliary agent, adding the mixture into an iron tank, and oscillating the mixture for 30 to 180 minutes under a closed condition;

and step 3: filtering the mixed solution obtained in the step 2 by using gauze to remove the grinding aid to obtain filtrate, namely the required gloss oil;

and 4, step 4: and (3) performing ultrasonic treatment on the carbon quantum dots with a certain mass in the step (1) and the varnish solution in the step (2) in ultrasonic waves for 20-50min until the carbon quantum dots are uniformly dissolved in varnish to obtain the fluorescent ink.

In a third aspect, the invention provides the use of the fluorescent ink of the first aspect in merchandise packaging or security applications.

In a fourth aspect, the present invention provides a fluorescent security label comprising a film and a pattern attached to the film, wherein the pattern is formed from the fluorescent ink according to the first aspect of the invention.

According to some preferred embodiments of the present invention, the pattern comprises a first pattern and a second pattern, wherein, in the fluorescent ink used for preparing the first pattern, the ratio of the mass of the carbon quantum dots to the volume of the varnish is 5-35 μ g/mL, preferably 10-30 μ g/mL; in the fluorescent ink used for preparing the second pattern, the ratio of the mass of the carbon quantum dots to the volume of the gloss oil is more than 40 μ g/mL, preferably 60-1000 μ g/mL, more preferably 100-.

The fluorescent ink disclosed by the invention has the following specific characteristics: the concentration of the carbon quantum dots in the gloss oil is different, so that the fluorescence color is different. The fluorescent ink prepared under the concentration of 10-30 mu g/mL can see blue fluorescence with naked eyes under a 365nm ultraviolet lamp, and can emit green fluorescence with the naked eyes when the concentration is more than 40 mu g/mL, so that the excitation wavelength dependence and the concentration dependence of the carbon quantum dots are well maintained, fluorescence quenching does not occur after the optical oil is added, and the possibility is provided for practical industrial application. The blue and green fluorescent ink can be prepared from the same fluorescent material only by simply adjusting the concentration, which is rare in the market, and the light resistance of the carbon quantum dots is good, so that the prepared fluorescent ink can stably exist for a long time. Furthermore, the prepared fluorescent ink also keeps the characteristic that the carbon quantum dots have fluorescence life difference under low concentration and high concentration, the average fluorescence life of the fluorescent ink under the concentration of 10 mu g/mL and 400 mu g/mL is respectively 3.26ns and 8.88ns, and the difference of the life values is large, so that the fluorescent ink can hide information in a time dimension, and the information safety and the anti-counterfeiting degree are high. Finally, the preparation process of the carbon quantum dots is simple, easy to operate and high in yield, so that the cost for preparing the fluorescent material is low, the purpose of preparing the fluorescent ink can be achieved only by simple ultrasonic dissolution, and the process is very simple, so that the feasibility of realizing industrial large-scale production is very high, and the method has a good application prospect.

Drawings

Fig. 1 is a diagram illustrating a synthesis process of a carbon quantum dot prepared according to embodiment 1 of the present invention.

Fig. 2 is an infrared absorption spectrum of a carbon quantum dot prepared according to embodiment 1 of the present invention.

Fig. 3 is a graph showing ultraviolet absorption of carbon quantum dots prepared according to embodiment 1 of the present invention.

Fig. 4 is an XRD spectrum of the carbon quantum dot prepared according to embodiment 1 of the present invention.

Fig. 5 is an XPS spectrum of a carbon quantum dot prepared according to embodiment 1 of the present invention.

Fig. 6 is a transmission electron microscope image (left) of a carbon quantum dot prepared according to embodiment 1 of the present invention and a lattice structure image (right) of the carbon quantum dot under a high power electron microscope.

FIG. 7 is a fluorescence spectrum of a carbon quantum dot prepared according to embodiment 1 of the present invention at a concentration of 10. mu.g/mL in an ethanol solution.

Fig. 8 is an emission spectrum of a carbon quantum dot prepared according to embodiment 1 of the present invention at different excitation wavelengths at a concentration of 10 μ g/mL in an ethanol solution.

FIG. 9 is a fluorescence spectrum of carbon quantum dots prepared according to embodiment 1 of the present invention at a concentration of 400. mu.g/mL in an ethanol solution.

Fig. 10 is an emission spectrum of a carbon quantum dot prepared according to embodiment 1 of the present invention at a concentration of 400 μ g/mL in an ethanol solution at different excitation wavelengths.

FIG. 11 is a graph showing fluorescence lifetimes of carbon quantum dots prepared according to embodiment 1 of the present invention at concentrations of 400. mu.g/mL and 10. mu.g/mL in an ethanol solution. (ii) a

Fig. 12 is an emission spectrum of the carbon quantum dot prepared according to embodiment 1 of the present invention at different concentrations in the ethanol solution.

Fig. 13 is an emission spectrum of carbon quantum dots prepared according to embodiment 1 of the present invention normalized at different concentrations in an ethanol solution.

Fig. 14 is a color coordinate graph corresponding to emission spectra of carbon quantum dots prepared according to embodiment 1 of the present invention at different concentrations in an ethanol solution.

FIG. 15 is a fluorescence spectrum of an ink having a concentration of 10. mu.g/mL according to embodiment 2 of the present invention.

FIG. 16 is an emission spectrum at different excitation wavelengths of an ink at a concentration of 10 μ g/mL according to embodiment 2 of the present invention.

FIG. 17 is a fluorescence spectrum of an ink having a concentration of 400. mu.g/mL in embodiment 1 according to the present invention.

FIG. 18 is an emission spectrum at different excitation wavelengths of an ink having a concentration of 400. mu.g/mL in embodiment 1 according to the present invention.

FIG. 19 is a color coordinate graph of emission spectra versus concentration (10. mu.g/mL and 400. mu.g/mL) of inks in accordance with embodiment 1 of the present invention.

FIG. 20 is a graph showing fluorescence lifetimes of inks at concentrations of 10. mu.g/mL and 400. mu.g/mL in embodiment 1 according to the present invention.

FIG. 21 is a graph showing the fluorescence effect of butterfly patterns printed with an ink having a concentration of 400. mu.g/mL (left panel) and a concentration of 10. mu.g/mL (right panel) under a 365nm ultraviolet lamp in accordance with embodiment 1 of the present invention.

Detailed Description

The following examples are given for the purpose of illustration only and are not intended to limit the scope of the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. It is not necessary or necessary to exhaustively enumerate all embodiments herein, and obvious variations or modifications can be made without departing from the scope of the invention.

Example 1

Step 1: preparation of carbon quantum dots

Adding 3g of citric acid and 3g of urea into a 100mL beaker, adding 10mL of high-purity water, stirring and dissolving to obtain a transparent solution, putting the beaker into a 750W microwave oven, adjusting the microwave oven to a medium-high level, heating for 5min, obtaining a carbonized black solid matter after the reaction is finished, transferring the carbonized black solid matter into an oven after slight cooling, adjusting the temperature to 60 ℃ and drying for 2h so as to remove unreacted micromolecules, then taking out the carbonized black solid matter, adding about 15mL of high-purity water, slowly stirring and dissolving the black solid matter, putting the dissolved solid matter into a high-speed centrifuge (15000r/min), centrifuging for 20min, filtering supernatant by using a filter membrane with the pore diameter of 0.45 mu m, and freeze-drying to obtain a brownish black carbon quantum dot.

Step 2: preparation of gloss oil

The gloss oil is prepared from the following components in parts by weight: 36g of polymer resin, 36g of n-butanol, 40g of ethanol and 1.2g of an auxiliary agent, wherein the used resin is polyamide resin, the used auxiliary agent is a drier, and the used grinding aid is 60g of glass beads. Weighing the substances in corresponding weight parts, adding the substances into an iron tank, oscillating and dispersing for 30min under a closed condition, slightly cooling, taking out, and filtering to remove the grinding aid, wherein the obtained solution is the gloss oil.

And step 3: preparation of fluorescent inks

Preparation of 400. mu.g/mL fluorescent ink A: 2.4mg of the carbon quantum dots obtained in the step 1 are weighed and added into a centrifuge tube filled with 6mL of the gloss oil obtained in the step 2, and the mixture is dissolved by ultrasonic to prepare 400 mu g/mL of fluorescent ink.

Preparation of 100. mu.g/mL fluorescent ink B: and (3) adding 2mg of the carbon quantum dots in the step (1) into a centrifuge tube filled with 20mL of the gloss oil in the step (2) to react for 20min under the ultrasonic condition, thus obtaining the fluorescent ink with the concentration of 100 mu g/mL.

Preparation of fluorescent ink C of 40. mu.g/mL: and (3) putting 4mL of the fluorescent ink B into a centrifuge tube, adding 6mL of the gloss oil obtained in the step (2), and uniformly mixing under an ultrasonic condition to obtain a mixed solution, namely 40 mu g/mL.

Preparation of 10. mu.g/mL fluorescent ink D: and (3) adding 1mL of the fluorescent ink C into a centrifuge tube, and uniformly mixing with 3mL of the gloss oil obtained in the step (2) under the ultrasonic condition to obtain a mixed solution which is 10 mu g/mL.

And 4, step 4: printing with fluorescent inks

Selecting a customized stamp, respectively coating pre-prepared printing inks A-D, wiping off redundant printing inks by a blank stamp pad, printing a pre-designed pattern on a BOPP film (biaxially-oriented polypropylene film), wherein the pattern of the printing ink A can emit green fluorescence visible to naked eyes under a 365nm ultraviolet lamp, the pattern of the printing ink B can emit green fluorescence, the pattern of the printing ink C can emit blue-green fluorescence, and the pattern of the printing ink D can emit blue fluorescence.

Example 2

Step 1: preparation of carbon quantum dots

Adding 4g of citric acid and 2g of urea into a 100mL beaker, adding 12mL of high-purity water, stirring and dissolving to obtain a transparent solution, putting the beaker into a 750W microwave oven, adjusting to a middle level, heating for 7min, obtaining a carbonized black solid matter after the reaction is finished, transferring the beaker into an oven after slight cooling, adjusting to 65 ℃ and drying for 1h so as to remove unreacted micromolecules, then taking out the beaker, adding 12mL of high-purity water, slowly stirring and dissolving the black solid matter, putting the dissolved solid into a high-speed centrifuge (14000r/min), centrifuging for 30min, filtering a supernatant by using a filter membrane with the aperture of 0.45 mu m, and freeze-drying to obtain a brownish black carbon quantum dot.

Step 2: preparation of gloss oil

The gloss oil is prepared from the following components in parts by weight: 36g of high polymer resin, 42g of n-butanol, 48g of ethanol and 1.2g of an auxiliary agent, wherein the used resin is polyamide resin, the used auxiliary agent is a drier, and the used grinding aid is 60g of glass beads. Weighing the substances in corresponding weight parts, adding the substances into an iron tank, oscillating and dispersing for 40min under a closed condition, slightly cooling, taking out, and filtering to remove the grinding aid, wherein the obtained solution is the gloss oil.

And step 3: preparation of fluorescent inks

Preparation of 100. mu.g/mL fluorescent ink: and (3) adding 2mg of the carbon quantum dots in the step (1) into a centrifuge tube filled with 20mL of the gloss oil in the step (2) to react for 20min under the ultrasonic condition, thus obtaining the fluorescent ink with the concentration of 100 mu g/mL.

Preparation of 10. mu.g/mL fluorescent ink: and (3) adding 1mL of prepared ink with the concentration of 100 mu g/mL into the gloss oil obtained in the step (2) to prepare 10mL of mixed solution, wherein the concentration of the obtained fluorescent ink is 10 mu g/mL.

And 4, step 4: printing with fluorescent inks

Selecting a customized stamp, coating the prepared ink, wiping off the redundant ink by a blank stamp pad, and then printing a pre-designed pattern on a BOPP film (biaxially-oriented polypropylene film), wherein the pattern can emit blue fluorescence visible to naked eyes under a 365nm ultraviolet lamp.

Example 3

Step 1: preparation of carbon quantum dots

Adding 4g of citric acid and 2g of urea into a 100mL beaker, adding 15mL of high-purity water, stirring and dissolving to obtain a transparent solution, putting the beaker into a 750W microwave oven, adjusting the temperature to a medium-high level, heating for 5min, obtaining a carbonized black solid matter after the reaction is finished, transferring the carbonized black solid matter into an oven after slight cooling, adjusting the temperature to 60 ℃ and drying for 2h so as to remove unreacted micromolecules, then taking out the carbonized black solid matter, adding 15mL of high-purity water, slowly stirring and dissolving the black solid matter, putting the dissolved solid matter into a high-speed centrifuge (13000r/min), centrifuging for 30min, filtering a supernatant by using a filter membrane with the aperture of 0.45 mu m, and freeze-drying to obtain a brownish black carbon quantum dot.

Step 2: preparation of gloss oil

The gloss oil is prepared from the following components in parts by weight: 36g of polymer resin, 36g of n-butanol, 54g of ethanol and 1.4g of an auxiliary agent, wherein the used resin is ketone-aldehyde resin, the used auxiliary agent is a plasticizer, and the used grinding aid is 60g of metal balls. Weighing the substances in corresponding weight parts, adding the substances into an iron tank, oscillating and dispersing for 50min under a closed condition, slightly cooling, taking out, and filtering to remove the grinding aid, wherein the obtained solution is the gloss oil.

And step 3: preparation of fluorescent inks

Preparation of 1200. mu.g/mL fluorescent ink: and (3) weighing 12mg of the carbon quantum dots obtained in the step (1), adding the carbon quantum dots into a centrifugal tube filled with 10mL of the gloss oil obtained in the step (2), and reacting for 30min under the ultrasonic condition to obtain the fluorescent ink with the concentration of 1200 mu g/mL.

Example 4

Step 1: preparation of carbon quantum dots

Adding 1.2g of citric acid and 4.8g of oxamide into a 100mL beaker, adding 10mL of high-purity water, stirring and dissolving to obtain a transparent solution, putting the beaker into a 750W microwave oven, adjusting to a medium level, heating for 15min, obtaining a carbonized black solid matter after the reaction is finished, transferring the mixture into an oven after slight cooling, adjusting to 50 ℃ and drying for 2h so as to remove unreacted micromolecules, then taking out the mixture, adding 15mL of high-purity water, slowly stirring and dissolving the black solid matter, putting the dissolved solid into a high-speed centrifuge (13000r/min), centrifuging for 25min, filtering a supernatant by using a filter membrane with the aperture of 0.45 mu m, and freeze-drying to obtain a yellow carbon quantum dot.

Step 2: preparation of gloss oil

The gloss oil is prepared from the following components in parts by weight: 30g of high polymer resin, 42g of n-butanol, 48g of ethanol and 0.9g of auxiliary agent, wherein the high polymer resin is polyurethane resin, the auxiliary agent is a surfactant, and the grinding aid is quartz sand with the weight of 60 g. Weighing the substances in corresponding weight parts, adding the substances into an iron tank, oscillating and dispersing for 100min under a closed condition, slightly cooling, taking out, and filtering to remove the grinding aid, wherein the obtained solution is the gloss oil.

And step 3: preparation of fluorescent inks

Preparation of 800. mu.g/mL fluorescent ink: and (3) weighing 8mg of the carbon quantum dots in the step (1), adding the carbon quantum dots into a centrifugal tube filled with 10mL of the gloss oil in the step (2), and reacting for 20min under the ultrasonic condition to obtain the fluorescent ink with the concentration of 800 mu g/mL.

Table 1 is a table of fluorescence lifetime data of carbon quantum dots prepared according to the present invention at concentrations of 400. mu.g/mL and 10. mu.g/mL in ethanol solution.

TABLE 1

Table 2 is a table of fluorescence lifetime data for inks of the present invention at concentrations of 400. mu.g/mL and 10. mu.g/mL.

TABLE 2

In the experimental process, based on the consideration of economic cost, manufacturing process and anti-counterfeiting effect, the experimental scheme in the embodiment 1 is selected to prepare the fluorescent ink emitting green fluorescence under the long wave of the ultraviolet lamp, and the concentration of the fluorescent ink is 400 mug/mL, while the experimental scheme in the embodiment 2 is selected to prepare the fluorescent ink emitting blue fluorescence under the long wave of the ultraviolet lamp. Therefore, the forgery prevention effect pattern and various representations of the present invention are exemplified by embodiment mode 1 and embodiment mode 2 of the present invention.

The invention has the following excellent effects: the fluorescent ink prepared by selecting the carbon quantum dots with excitation wavelength dependence and concentration dependence as the fluorescent material has the advantages that: the prepared fluorescent ink well keeps the fluorescence property of the carbon quantum dots, namely the prepared fluorescent ink also generates the fluorescence property of excitation wavelength dependence and concentration dependence, and the anti-counterfeiting grade is higher and the anti-counterfeiting ink is more difficult to imitate for other fluorescent inks only with single fluorescent color; the prepared fluorescent ink not only respectively emits blue fluorescence and green fluorescence at the concentration of 5-35 mu g/mL, preferably 10-30 mu g/mL and the concentration of 100-400 mu g/mL, such as 350-400 mu g/mL, but also can perform information anti-counterfeiting encryption on the time dimension according to the difference of the fluorescence lifetimes of the two, thereby further increasing the anti-counterfeiting level; the carbon quantum dot material prepared by the method is simple and easy to obtain, low in price and relatively low in manufacturing cost; and fourthly, the ink which can emit macroscopic blue and green fluorescence under an ultraviolet lamp can be obtained only by adding a small amount of carbon quantum dots during preparation, so that the preparation cost is low, and the economic benefit is good. And the preparation process is very simple and convenient, so that the feasibility of realizing industrialization is very high, and the method has a good application prospect.

Claims

1. The fluorescent ink based on the carbon quantum dots comprises the carbon quantum dots and gloss oil, wherein the gloss oil comprises an organic solvent, a high polymer resin and an auxiliary agent, and preferably, the gloss oil comprises 50-75 parts by weight of the organic solvent, 25-35 parts by weight of the high polymer resin and 0.2-2 parts by weight of the auxiliary agent.

2. Fluorescent ink according to claim 1, characterized in that the organic solvent is selected from one or several of ethanol, propanol and n-butanol, preferably the organic solvent consists of ethanol and n-butanol.

3. The fluorescent ink according to claim 1, wherein the polymer resin is one or more of polyamide resin, polyurethane resin, ketone-aldehyde resin and acrylic resin, and the auxiliary agent is one or more of a drier, a viscosity reducer, a plasticizer, a defoamer, an antioxidant and a surfactant.

4. A fluorescent ink according to any of claims 1 to 3, wherein the carbon source comprises one or more of citric acid, salicylic acid and malic acid; the nitrogen source is one or more of urea, oxamide, ammonia water and ammonium bicarbonate; the mass ratio of the carbon source to the nitrogen source is preferably 1:2 to 2:1, more preferably 1:1.2 to 1.2: 1.

5. A fluorescent ink according to any of claims 1 to 3, characterized in that the ratio of the mass of the carbon quantum dots to the volume of the varnish is 5-35 μ g/mL, preferably 10-30 μ g/mL; or

The ratio of the mass of the carbon quantum dots to the volume of the gloss oil is more than 40 mu g/mL, preferably 60-1000 mu g/mL, more preferably 100-600 mu g/mL, such as 350-400 mu g/mL.

6. Method for the preparation of a fluorescent ink according to any of claims 1 to 5, comprising the steps of:

(2) mixing the gloss oil and the carbon quantum dots under ultrasonic conditions, wherein the ultrasonic time is preferably 20-50 minutes.

7. The method according to claim 6, wherein the preparation of the carbon quantum dots comprises heating an aqueous solution of a carbon source and a nitrogen source under microwave conditions, preferably at 600-750W for 5-15 minutes, thereby obtaining a carbonized material, purifying and drying the carbonized material to obtain the carbon quantum dots;

the grinding aid is selected from one or more of glass beads, metal balls and quartz sand.

8. Use of the fluorescent ink according to any one of claims 1 to 6 for anti-counterfeiting of merchandise packaging or tickets.

9. A fluorescent security label comprising a film and a pattern attached to the film, wherein the pattern is prepared from the fluorescent ink of any one of claims 1-6.

10. The fluorescent security label according to claim 9, wherein the pattern comprises a first pattern and a second pattern, wherein the ratio of the mass of the carbon quantum dots to the volume of the varnish in the fluorescent ink used for preparing the first pattern is 5-35 μ g/mL, preferably 10-30 μ g/mL; in the fluorescent ink used for preparing the second pattern, the ratio of the mass of the carbon quantum dots to the volume of the gloss oil is more than 40 μ g/mL, preferably 60-1000 μ g/mL, more preferably 100-.