Quantum dot anti-counterfeiting composition

Abstract

The application discloses a quantum dot anti-counterfeiting composition, an anti-counterfeiting coding mode based on the composition and an anti-counterfeiting identification method. The composition comprises two or more than two quantum dot materials, and at least two quantum dot materials in the composition have different emission wavelengths and quenching times of emitted light generated under the same excitation condition, wherein the emission wavelength of the emitted light is 350-780 nm; the same excitation condition at least includes the same wavelength of excitation light, and optionally, at least one of the following conditions is the same: an atmosphere, a solvent atmosphere or a temperature condition during excitation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanomaterials and their applications, in particular, to a quantum dot material-based anti-counterfeiting composition and its preparation and application. BACKGROUND

[0002] Quantum dots (QDs) generally refer to nanocrystals with a radius less than or close to the exciton Bohr radius, and in particular to semiconductor nanocrystals. The particle size of quantum dots is generally 1 nanometer to several tens of nanometers, and is usually spherical or spherical-like structure. Due to the quantum confinement of electrons and holes, the continuous energy band structure becomes a discrete energy level structure with molecular characteristics, and the band gap increases with the decrease of size. Therefore, after excitation, fluorescence can occur, and various special physical effects (such as quantum size effect, surface effect, dielectric confinement effect, quantum tunneling effect, and Coulomb blocking effect, etc.) are exhibited.

[0003] At present, quantum dot materials are usually prepared from II-VI, IV-VI or III-V semiconductor materials. Common quantum dot materials include II-VI semiconductor quantum dots such as cadmium sulfide (CdS), cadmium tin (CdSe), cadmium telluride (CdTe), and zinc sulfide (ZnS); IV-VI semiconductor quantum dots such as lead sulfide (PbS), lead selenide (PbSe); III-V semiconductor quantum dots such as indium phosphide (InP), indium arsenide (InAs). In addition, quantum dot materials based on perovskite structure and carbon quantum dot materials have also been developed.

[0004] Generally, quantum dot materials can be widely used in energy conversion, light-emitting display devices, photoelectric detection molecular probes, spectral equipment, biological markers and development, etc. In recent years, quantum dot materials have also been gradually applied to the field of anti-counterfeiting detection due to their fluorescence properties.

[0005] Reference document 1 discloses an anti-counterfeiting ink based on zinc oxide quantum dots, which emits light in the ultraviolet (wavelength 380 nm) region after excitation, unlike existing quantum dots that emit light in the visible spectrum range upon excitation. Reference document 2 discloses a printable anti-counterfeiting fluorescent water-based ink based on hydrophilically modified oil-soluble quantum dots selected from core-shell quantum dots CdSe / ZnS, CdSe / CdS / ZnS, etc., which has improved use stability compared to traditional semiconductor quantum dot fluorescent inks based on organic solvents.

[0006] Reference document 3 discloses a UV fluorescent anti-counterfeiting film based on nitrogen-doped carbon quantum dots, which can produce strong blue fluorescence after light excitation. Reference document 4 discloses an amphiphilic graphene quantum dot material with good dispersibility. By adjusting the concentration of added graphene quantum dot material, the composition of the solvent and other factors affecting the aggregation state of graphene quantum dot aggregates, the continuous quantitative regulation of the fluorescence emission spectrum can be realized, thereby realizing the adjustable fluorescence coding anti-counterfeiting mark.

[0007] Further, although efforts have been made to improve the fluorescence efficiency of various quantum dot materials, the relatively single fluorescence color is also not conducive to the security of anti-counterfeiting measures. Therefore, in order to expand the anti-counterfeiting properties of quantum dot materials, technologies such as multi-color luminescence, multi-mode luminescence, multi-response luminescence, and delayed fluorescence have been developed.

[0008] Reference document 5 discloses a fluorescent anti-counterfeiting ink based on multi-color fluorescent carbon quantum dots, which has high fluorescence efficiency and can produce different wavelengths of emission spectrum under the action of different excitation light. Reference document 6 discloses a method for synthesizing different color fluorescent carbon quantum dot materials using citric acid as the main body. By mixing these quantum dot materials with different fluorescence colors, a fluorescent dye with multiple colors can be obtained.

[0009] Reference document 7 discloses a dual-mode luminescent water-based anti-counterfeiting ink. By doping carbon quantum dots with rare earth elements, both up-conversion and down-conversion luminescence modes can be achieved.

[0010] Reference document 8 discloses a solvent-responsive multi-mode fluorescent carbon quantum dot ink. The quantum dots have different emission wavelengths in water and in organic solvents.

[0011] Reference document 9 discloses a visible light-excited thermal active delayed fluorescence material based on carbon quantum dots. Without the need for transition metal doping, it can produce blue-green thermal active delayed fluorescence under UV excitation, and also produce blue-green thermal active delayed fluorescence under visible light. Reference document 10 discloses a rare earth element-doped carbon quantum dot fluorescent material. The fluorescent ink containing this material not only changes the fluorescence color under acid and alkaline atmosphere stimulation, but also has a relatively large change in fluorescence lifetime.

[0012] Although the above-mentioned methods have been tried in the field of security and anti-counterfeiting, there is still room for further exploration in terms of new, higher security level, more difficult to counterfeit anti-counterfeiting measures based on quantum dot materials.

[0013] Reference documents:

[0014] Reference document 1: CN107057688A

[0015] Reference 2: CN112175449A

[0016] Reference 3: CN112300787A

[0017] Reference 4: CN110615428A

[0018] Reference 5: CN110330969A

[0019] Reference 6: CN110408388A

[0020] Reference 7: CN110591450A

[0021] Reference 8: CN109943148A

[0022] Reference 9: CN111040759A

[0023] Reference 10: CN112457842A SUMMARY

[0024] Problem to be solved by the invention

[0025] Based on the special optical properties of quantum dot materials, various anti-counterfeiting compositions or markers have been designed, and based on such compositions and markers, people can prepare or identify security features or anti-counterfeiting features in an encrypted manner.

[0026] References 1-4 attempt to adjust the emission wavelengths of light produced under different excitation conditions for the examiner to check, although there have been improvements in dispersibility, luminous efficiency and stability, but the wavelengths of light emitted or detected by the examiner are usually single.

[0027] In references 5-8, quantum dot materials that can produce multiple colors after excitation are attempted, but usually the excitation conditions need to be converted for the examiner to distinguish different colors of emitted light. In addition, references 9 and 10 creatively use the characteristics of delayed fluorescence, and after a single excitation, the delayed fluorescence lifetime is detected as an anti-counterfeiting feature.

[0028] However, as people's requirements for anti-counterfeiting means on security documents or security products continue to rise, relying solely on the detection of the characteristics of the emission wavelength of quantum dot materials after a single excitation is sometimes difficult to resist the risk of fraud and counterfeiting.

[0029] Based on such a reality, the present application provides an anti-counterfeiting coding means based on different fluorescence quenching times of various quantum dots with different emission wavelengths, which can provide dynamic emission wavelength conversion characteristics within the illumination time. Therefore, a dynamic emission wavelength conversion and time-responsive dual optical anti-counterfeiting means are provided, further improving the anti-counterfeiting level and the difficulty of imitation.

[0030] In addition, the anti-counterfeiting method provided by the present application is simple to manufacture and easy to check by the terminal security file and security product identification.

[0031] Solution for solving the problem

[0032] Through long-term and painstaking research by the inventors, it is found that the above technical problems can be solved by the following technical solutions:

[0033] [1]. The present application first provides an anti-counterfeiting composition, wherein the composition comprises two or more quantum dot materials and a photoinitiator, and,

[0034] The emission wavelengths and quenching times of the emitted light generated by at least two of the quantum dot materials in the composition under the same excitation condition are different, wherein,

[0035] The emission wavelength of the emitted light of each quantum dot material is in the range of 350-780 nm;

[0036] The same excitation condition at least includes the same wavelength of excitation light, and optionally, at least one of the following conditions is the same: atmosphere, solvent atmosphere, or temperature condition during excitation.

[0037] [2]. The composition according to [1], wherein the quantum dot materials have 2-10 quantum dot materials with different emission wavelengths and quenching times of the emitted light generated under the same excitation condition.

[0038] [3]. The composition according to [1] or [2], wherein the different emission wavelengths are different by 30 nm or more between the quantum dot materials under the same excitation condition; and the different quenching times are different by 0.5 s or more between the quantum dot materials under the same excitation condition.

[0039] [4]. The composition according to any one of [1]-[3], wherein the composition further comprises one or more of a photoinitiator, a photopolymerizable monomer, a photopolymer active oligomer, a coupling agent, and a solvent.

[0040] [5]. The composition according to any one of [1]-[4], wherein the emitted light of the quantum dot material under the excitation condition comprises fluorescence, and optionally further comprises phosphorescence or delayed fluorescence.

[0041] [6]. The composition according to any one of [1] to [5], wherein the atmosphere atmosphere comprises an oxygen-containing atmosphere or an oxygen-free atmosphere; the solvent atmosphere comprises an organic solvent or water; and the temperature condition is in the range of -30 to 60 °C.

[0042] [7]. The composition according to any one of [1] to [6], wherein the emission wavelength or the quenching time of the quantum dot material has at least one of the following responses: an atmosphere atmosphere response, a solvent atmosphere response, or a temperature response.

[0043] [8]. Further, the present application provides an anti-counterfeiting ink or paint, wherein the ink or paint comprises the composition according to any one of [1] to [7] above.

[0044] [9]. Further, the present application also provides an optical anti-counterfeiting layer, wherein the anti-counterfeiting layer comprises the composition according to any one of [1] to [7] above.

[0045]

[10] . In addition, the present application provides an anti-counterfeiting encoding method, wherein the method comprises:

[0046] selecting or adjusting the types or contents of the quantum dot materials in the composition according to any one of [1] to [7] above, wherein at least two of the adjusted quantum dot materials have different emission wavelengths and quenching times of the emitted light under the same excitation condition.

[0047]

[11] . In addition, the present application also provides an anti-counterfeiting identification method, wherein the method comprises:

[0048] i) obtaining an article having a security mark or an anti-counterfeiting layer;

[0049] ii) irradiating the security mark or the anti-counterfeiting layer of the article with excitation light having a wavelength of 254 to 395 nm;

[0050] detecting whether the security mark or the anti-counterfeiting layer produces a change in the wavelength of the emitted light within the excitation light irradiation time period or detecting the time at which the security mark or the anti-counterfeiting layer produces a change in the wavelength of the emitted light within the excitation light irradiation time period, and comparing it with the standard information of the composition or the dried product thereof according to any one of [1] to

[10] above.

[0051]

[12] . The method according to

[11] , wherein the step ii) is performed under one or more different atmosphere atmospheres, solvent atmospheres, or temperature conditions.

[0052] Effects of the invention

[0053] Based on the implementation of the above technical solutions, the present application can obtain the following technical effects:

[0054] 1) The present application provides a novel anti-counterfeiting composition, and the anti-counterfeiting features or marks formed based thereon have a flexible encoding method;

[0055] 2) Based on the encoding method of 1) above, when detection is performed, the anti-counterfeiting features or marks exhibit dynamic changes in the wavelength of emitted light (color of emitted light) after excitation within the detection time;

[0056] 3) The anti-counterfeiting inks / paints or anti-counterfeiting layers formed based on the encoding method achieve multi-dimensional information encryption (dynamic color change and time of color conversion), and the possibility of being counterfeited is extremely low, thus improving the security of the anti-counterfeiting measures;

[0057] 4) The quantum dot anti-counterfeiting composition of the present application has stable optical and chemical properties, the overall technical solution is simple to operate and easy to promote on a large scale, and the detection conditions are not high when detection is performed. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 Color change of the composition in Example 1 under anaerobic conditions within the irradiation time period DETAILED DESCRIPTION

[0059] Hereinafter, the content of the present application will be described in detail. The description of the technical features described below is based on representative embodiments, specific examples of the present application, but the present application is not limited to these embodiments, specific examples. It should be noted that:

[0060] In the present specification, the numerical range represented by "numerical value A ~ numerical value B" means a range including the end point numerical values A and B.

[0061] In the present specification, "substantially" or "essentially" means that the standard deviation from the theoretical model or theoretical data is within 5%, preferably 3%, and more preferably 1%.

[0062] In the present specification, unless otherwise specified, "%" means mass percent.

[0063] In the present specification, "room temperature" is used as a reference to a temperature range of 10 to 35°C.

[0064] In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0065] In the present specification, "quantum dots" have the same physical and chemical meanings as "quantum dot crystals" and "quantum dot materials".

[0066] In this specification, "optional" or "optionally" means that the subsequently described event or circumstance can or can not occur, and that the description includes instances where the event occurs and instances where it does not.

[0067] In this specification, references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc. mean that the particular element(s) described in connection with such embodiments is included in at least one embodiment described herein, and can or can not be present in other embodiments. In addition, it should be understood that the described elements can be combined in a variety of ways without departing from the scope of the application.

[0068] The present application provides a dynamic anti-counterfeiting method which is different from the existing anti-counterfeiting method based on the optical properties of quantum dot materials. It can dynamically detect or observe the shift of the emission wavelength or the change of the emission color of the quantum dot materials within the detection time, based on the differences in the emission wavelength and the quenching time of the emitted light of different quantum dot materials after receiving excitation.

[0069] <First aspect>

[0070] In the first aspect of the present application, an anti-counterfeiting composition based on quantum dot materials is provided, which contains two or more different quantum dot materials.

[0071] For the different quantum dot materials, in the present application, it means that under the same excitation condition, the quantum dot materials have different emission wavelengths and quenching times of the emitted light in the composition. In some specific embodiments of the present application, the same excitation condition also includes at least one of the same atmospheric environment, solvent environment or temperature condition when the quantum dot materials are excited.

[0072] Quantum dot material

[0073] In the present application, two or more quantum dot materials can be mixed for use. In principle, the present application does not have special restrictions on these quantum dot materials, as long as at least two quantum dot materials contained therein have different emission wavelengths and quenching times of the emitted light under the same excitation condition in the composition.

[0074] For the quantum dot materials suitable for use in the present application, in some specific embodiments, they can include:

[0075] Group II-VI semiconductor quantum dot materials such as cadmium sulfide (CdS), cadmium stannate (CdSe), cadmium telluride (CdTe) and zinc sulfide (ZnS);

[0076] Group IV-VI semiconductor quantum dot materials such as lead sulfide (PbS), lead selenide (PbSe), etc.

[0077] Group III-V semiconductor quantum dot materials such as indium phosphide (InP), indium arsenide (InAs), etc.

[0078] Quantum dot materials with core-shell structure such as CdS / ZnS, CdSe / CdS, CdSe / ZnS, CdSe / CdS / ZnS, CdTe / CdS, CdTe / CdS / ZnS, ZnSe / ZnS, InP / ZnSe, InP / ZnS, InP / ZnSe / ZnS, InP / GaP / ZnS, etc.

[0079] Quantum dot materials of noble metal elements such as Au, Ag, etc.

[0080] and one or more of quantum dot materials based on perovskite structure and carbon quantum dot materials, etc.

[0081] Further, the present application is not particularly limited to the method for synthesizing these quantum dot materials, and the method can be either an organic medium-based method or an aqueous medium-based method.

[0082] In some specific embodiments of the present application, the quantum dot materials suitable for the present application can be selected from colloidal quantum dot materials. For the synthesis method of such quantum dot materials, typically, the raw materials can be first dissolved in an organic solvent or a ligand to form a precursor, and then mixed under heating conditions to form quantum dots through chemical reaction.

[0083] For the above-mentioned organic solvent or ligand, it is to be noted that the organic solvent itself can also be a ligand when preparing the precursor, and therefore, the organic solvent can generally be classified into ligand-type organic solvents and non-ligand-type organic solvents.

[0084] In some specific embodiments of the present application, the ligand or ligand-type solvent generally has a high boiling point (preferably, for example, a boiling point of 300°C or higher) and dissolves the raw materials to form a quantum dot precursor. The ligand or ligand-type solvent is commonly some polar organic solvents with long-chain alkyl groups, including acid compounds, amine compounds, thiol compounds, and phosphorus-containing compounds with long-chain alkyl groups, etc. Specific examples can include oleylamine, dodecyl mercaptan, oleic acid, dioctyl ether, tri-octyl phosphine oxide (TOPO), tri-octyl phosphine (TOP), hexyl phosphonic acid (HPA), tetradecyl phosphonic acid (TDPA), etc. and mixtures thereof.

[0085] For the non-ligand solvent, it can be octadecene, diphenyl ether, paraffin oil, methylpyrrolidone, etc. In addition, depending on the required reaction temperature, the non-ligand solvent can also be a low-boiling point solvent such as ethanol or toluene when the reaction temperature allows. For the use of the non-ligand solvent, the precursor can be dissolved or dispersed in these solvents after the precursor is obtained by dissolving the raw material in the ligand or the ligand solvent.

[0086] For the reaction mode, there is no particular limitation, and it can be that two or more precursors are simultaneously injected into another organic solvent under heating to perform the growth reaction of the quantum crystal after the precursors are prepared by means of the ligand or the ligand organic solvent, respectively; or it can be that one ligand is injected into another ligand solution to perform the growth reaction of the quantum crystal under heating.

[0087] For the above-mentioned raw material, it is mainly the source of various elements in the quantum dot. For these raw materials, it can be one or more of the elemental substance, oxide, salt compound, organic compound, etc. For example, in some specific embodiments, when synthesizing the quantum dot of type A x B y (wherein A can be Cd, Hg, Pb, Zn, Ag, Cu, Mn, Sn, Ni, Bi or Eu, etc.; and B can be S, Se or Te), the oxide, salt compound or organic compound of A can be dissolved in the ligand or the ligand organic solvent to obtain the precursor, and in addition, the elemental substance of B is dissolved in the organic solvent to form another precursor, and then the two precursors are mixed under heating to prepare the quantum dot.

[0088] For the temperature condition when preparing the quantum dot, the present application has no particular limitation, and for example, in the hot injection method, the reaction temperature can be controlled in the range of 180-380°C as required.

[0089] In some other specific embodiments of the present application, the quantum dot material suitable for the present application can be selected from the quantum dot material synthesized in an aqueous medium, such as the perovskite quantum dot material. For the synthesis method of such quantum dot material, the present application also has no particular limitation, and the raw material can be dissolved in water, and in the presence of a surfactant, hydrothermal synthesis is performed to obtain it. For such surfactant, it can be a compound with a bipolar head, and typically, it can be an alkyl acid compound with a mercapto group, etc.

[0090] In addition, the carbon quantum dot material can also be used as the quantum dot material of the present application. Generally, the carbon source (such as citric acid, etc.) and the nitrogen source (such as amine compound) are heated in the range of 150-300°C, and then dispersed in water to obtain it.

[0091] In addition, without limitation, in order to obtain desired optical properties (e.g. adjusting the emission wavelength), other elements, such as rare earth elements, etc. can be doped during the above-mentioned various quantum dot preparation processes, or the obtained quantum dot material can be surface-modified, etc.

[0092] For the surface modification, there is no particular limitation. For example, in order to obtain quantum dot materials with different properties, or in order to meet the application of quantum dots in different application fields, such as improving the redispersibility of quantum dot materials in different physical and chemical situations, and improving or enhancing the optoelectronic properties of quantum dot materials, etc., the ligands of the quantum dot materials obtained from the synthesis stock solution need to be adjusted or the quantum dot materials need to be surface-modified. For example, the quantum dot materials obtained by the conventional hot injection method have oil solubility, but if the materials need to be redispersed in an aqueous system, the ligands on the surface of the quantum dots need to be adjusted. Therefore, the adjustment of the ligands on the surface of the quantum dots also determines their use effect. In some specific embodiments, the above-mentioned surface modification is carried out by means of ligand exchange. Without limitation, such surface modification can be carried out by introducing second, third or more other ligands.

[0093] In the present application, the morphology of the quantum dot material is not particularly limited, and in some specific embodiments, it can be a crystalline material with a certain shape. Typically, the morphology of the quantum dot material of the present application can have, for example, a spherical or substantially spherical structure, a rod-like structure, a sheet-like structure, a conical structure, a tower-like structure, a polygonal structure, a cubic structure, etc. In some preferred embodiments of the present application, the obtained quantum dot crystal has a spherical or substantially spherical morphology; in some other preferred embodiments, the obtained quantum dot crystal has a core-shell structure (spherical or substantially spherical).

[0094] The particle size of the quantum dot material of the present application is not particularly limited, and in some specific embodiments of the present application, it can be in the range of 1-100 nm, preferably in the range of 2-70 nm, more preferably in the range of 2-60 nm, further preferably in the range of 2-50 nm, still further preferably in the range of 3-30 nm, 3-20 nm or 3-10 nm.

[0095] In addition, in the present application, the quantum dot material of the present application, after being excited, emits light of at least one type, i.e. fluorescence, or in some other specific embodiments, the quantum dot material emits light of at least one type in addition to fluorescence, i.e. phosphorescence or (thermal) delayed fluorescence.

[0096] Anti-counterfeiting composition

[0097] The anti-counterfeiting composition of the present application, primarily, comprises two or more kinds of quantum dot materials. In some preferred embodiments, the anti-counterfeiting composition of the present application comprises 2 to 10 kinds of quantum dot materials, and further preferably comprises 3 to 5 kinds of quantum dot materials.

[0098] For the composition form of the above-mentioned composition, in some specific embodiments, a plurality of quantum dot materials can be dispersed in a solvent to form a dispersion system. For the kind of solvent, there is no particular limitation, and it can be various solvents commonly used in the art as will be described below. For the concentration of various quantum dots in the dispersion system, there is no particular limitation, and it can be adjusted in accordance with the excitation characteristics, and therefore, the concentrations of different quantum dot materials do not have to be the same. In some specific embodiments, for the concentration of the total quantum dot material in the composition, it can be 1 to 40 v%, and preferably 3 to 25 v% by volume.

[0099] Further, for the above-mentioned quantum dot materials in the anti-counterfeiting composition of the present application, at least two of the quantum dot materials have different emission wavelengths of the emitted light and different quenching times under the same excitation condition. That is, the quantum dot materials have different emission wavelengths of the emitted light and different quenching times under the same excitation condition under the composition conditions. And, in some preferred embodiments, the emission wavelengths and / or quenching times of the quantum dot materials in the composition of the present application have one or more conditions responsiveness (change with the change of the conditions) of the atmospheric atmosphere, the solvent atmosphere, or the temperature conditions.

[0100] In some specific embodiments, the wavelength of the emitted light of the quantum dot materials in the anti-counterfeiting composition can be 350 to 780 nm, and from the perspective of identification convenience, the preferred wavelength of the emitted light is 380 to 640 nm, and more preferably 440 to 570 nm. For the wavelength of the excitation light, in some specific embodiments, it can be 254 to 395 nm, and preferably 350 to 390 nm.

[0101] Further, in some preferred embodiments of the present application, 3 to 5 of the quantum dot materials in the composition have different emission wavelengths of the emitted light and different quenching times, respectively, under the same excitation condition.

[0102] For the emission wavelength, in some specific embodiments of the present application, the difference in the wavelength of the emitted light between two quantum dot materials can be 15 nm or more, preferably 30 nm or more, and further preferably 60 nm or more; and there is no particular limitation on the upper limit of the difference in the wavelength of the emitted light, and it can be typically 200 nm or less, and preferably 150 nm or less. If the difference in the wavelength of the emitted light is too small, the detection convenience and the distinguishability can be reduced, and if the difference in the wavelength of the emitted light is too large, the detection wavelength range requirement of the detection instrument will be increased.

[0103] For the quenching time described in the present application, it refers to the phenomenon that the emission light generated in the anti-counterfeiting composition is attenuated or terminated when the excitation light is irradiated. The quenching time of the quantum dots in the composition is not only related to the optical properties of the quantum dot material itself, but also related to other components in the composition and the detection environment. More specifically, for the quenching time, the present application refers to the time t when the luminescence intensity or quantum efficiency is 20% or less of the initial luminescence intensity or quantum efficiency after the excitation light irradiation starts. In some specific embodiments of the present application, the difference in quenching time between the two quantum dot materials can be 0.5 s or more, in some specific embodiments, it can be 1 s to 60 s, preferably 5 to 40 s, more preferably 15 to 30 s. Further, the quenching time of each quantum dot material or the difference in quenching time can be adjusted by the selection of the quantum dot material or the composition of the anti-counterfeiting composition and the physical, chemical or temperature conditions during detection, etc.

[0104] For the photoinitiator of the present application, it can be selected from one or more cleavage type initiators, which can include benzoin derivatives, benzoin ketone derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-amine alkyl phenone, acyl phosphine oxide, ester oxime ketone compound, aryl peroxide ester compound, halomethyl aryl ketone, organic sulfur-containing compound, benzoyl formate, etc. In addition, for the concentration of the photoinitiator, in some specific embodiments, it can be 0.5 to 4 mass% based on the total mass of the composition.

[0105] For the initiator, it can generate free radicals under light irradiation, and the efficiency of the quantum dot materials of different emission wavelengths to capture free radicals is different, resulting in different quenching sequences of quantum dots of different emission wavelengths, and causing the process of displaying color change with irradiation time. In addition, as preferred, in the presence of monomers in the system described below, the quantum dot material captures free radicals and the polymerization and curing of the monomers are carried out simultaneously, and the free radicals are difficult to move after the monomers are completely cured, thus, the process of color change can be more convenient to display.

[0106] Therefore, the initiator can play a major role in color regulation, and the color change sequence is determined by the electron gain and loss ability of the quantum dot material. In some specific embodiments, the color change time can be adjusted by the amount of initiator.

[0107] For other components in the anti-counterfeiting composition of the present application, in some specific embodiments, these other components can include one or more of photopolymerizable monomers, photopolymer active oligomers, coupling agents, solvents, etc.

[0108] For the photo-polymerizable monomer, one or more of acrylic monomers including (meth)acrylic acid, (meth)acrylate, epoxy (meth)acrylate, polyurethane (meth)acrylate, tri-functional or more poly(meth)acrylate, etc. can be selected.

[0109] For the photo-polymerizable monomer, one or more of acrylic monomers including (meth)acrylic acid, (meth)acrylate, epoxy (meth)acrylate, polyurethane (meth)acrylate, tri-functional or more poly(meth)acrylate, etc. can be selected.

[0110] For the coupling agent, one or more of silane coupling agents can be selected without particular limitation.

[0111] For the solvent, there is no particular limitation and it can be an organic solvent or water. Examples of such solvents include, but are not limited to, alcohols (e.g., methanol, ethanol, isopropanol, n-propanol, ethoxypropanol, n-butanol, sec-butanol, t-butanol, isobutanol, 2-ethylhexanol, and mixtures thereof); polyhydric alcohols (e.g., glycerol, 1,5-pentanediol, 1,2,6-hexanetriol, and mixtures thereof); esters (e.g., ethyl acetate, n-propyl acetate, n-butyl acetate, and mixtures thereof); carbonates (e.g., dimethyl carbonate, diethyl carbonate, di-n-butyl carbonate, 1,2-ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, and mixtures thereof); aromatic solvents (e.g., toluene, xylene, phenylcyclohexane, and mixtures thereof); ketones and ketone alcohols (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol, and mixtures thereof); amines (e.g., dimethylformamide, dimethylacetamide, and mixtures thereof); aliphatic or alicyclic hydrocarbons; chlorinated hydrocarbons (e.g., dichloromethane, trichloromethane, or mixtures thereof); nitrogen-containing heterocyclic compounds (e.g., N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and mixtures thereof); ethers (e.g., diethyl ether, tetrahydrofuran, dioxane, and mixtures thereof); alkyl ethers of polyhydric alcohols (e.g., 2-methoxyethanol, 1-methoxypropan-2-ol, and mixtures thereof); alkylene glycols, alkylene thio glycols, polyalkylene glycols, or polyalkylene thio glycols (e.g., ethylene glycol, polyethylene glycol (e.g., diethylene glycol, triethylene glycol, tetraethylene glycol), propylene glycol, polypropylene glycol (e.g., dipropylene glycol, tripropylene glycol), butylene glycol, thiodiethylene glycol, hexylene glycol, and mixtures thereof); nitriles (e.g., acetonitrile, propionitrile, and mixtures thereof), and sulfur-containing compounds (e.g., dimethyl sulfoxide, sulfolane, and mixtures thereof). Preferably, the organic solvent includes a solvent having a high boiling point (boiling point of 150°C or more) or a polar solvent.

[0112] Anti-counterfeiting code

[0113] By adjusting the composition of the above-mentioned composition, such as the type, content, initiator concentration of quantum dot material, etc., the encoding of the following (but not limited to) anti-counterfeiting features can be realized.

[0114] In some specific embodiments of the present application, when the composition exists in the form of a solution containing a solvent, the composition is irradiated by using an excitation light source. Among them, for the total irradiation time T of the excitation light source, at the initial irradiation time T0, the quantum dot material in the composition is excited to produce two or more wavelengths of emission light; when reaching the irradiation time T1, at least one quantum dot material in the composition produces light emission quenching, and at least one other quantum dot material has not yet occurred light emission quenching. At this time, the observer or detector can detect the change of the composition light emission wavelength or light emission color at the time points of T0 and T1.

[0115] In some other cases, if the irradiation is still continued after the T1 time point, when reaching the irradiation time T2, at least one quantum dot material in the composition again produces light emission quenching, and at least one other quantum dot material has not yet occurred light emission quenching; further in this way, the observer or detector can detect the change of the composition light emission wavelength or light emission color at the time points of T0 and T1, T2…Tn. n

[0116] By selecting and using quantum dot materials, such as adjusting the type and amount / concentration of quantum dot materials, as long as the appropriate combination of quenching time is selected, the change of two or more light emission wavelengths or colors can be dynamically observed within the entire irradiation time T. According to such principles, the anti-counterfeiting maker can pre-design the quantum dot material composition of the anti-counterfeiting composition, and perform anti-counterfeiting identification according to the color change or according to one or more time points of the color change when performing anti-counterfeiting detection.

[0117] Similarly, in some other specific embodiments of the present application, when the composition appears in the form of a dry mark, feature or coating, the change of emission wavelength or color at different irradiation times can also be realized by the selection and cooperation of quantum dot materials.

[0118] In addition, as mentioned earlier, the emission wavelength and / or quenching time of the quantum dot material in the composition of the present application has one or more conditions of atmosphere, solvent atmosphere or temperature conditions. For example:

[0119] a. When the type of solvent in the composition is changed, the dynamic optical change characteristics of the anti-counterfeiting composition within the light irradiation time can be changed;

[0120] b. When a (different) solvent is applied to a dry composition without solvent, the dynamic optical change characteristics of the anti-counterfeiting composition within the light irradiation time can be changed;​

[0121] c. When the atmosphere of the composition is changed (e.g. with oxygen atmosphere and without oxygen atmosphere), the dynamic optical change characteristics of the anti-counterfeiting composition in the light exposure time can be changed;

[0122] d. When the detection temperature is changed (e.g. in the range of -30~60℃ or in the range of room temperature), the dynamic optical change characteristics of the anti-counterfeiting composition in the light exposure time can be changed.

[0123] The dynamic optical change characteristics mentioned above at least include the color characteristics of the dynamic optical change and the time characteristics of the dynamic optical change.

[0124] Therefore, the present application also allows the anti-counterfeiting composition to be anti-counterfeiting coded according to the above-mentioned responsiveness.

[0125] <Second aspect>

[0126] In the second aspect of the present application, an anti-counterfeiting ink or coating based on the above-mentioned anti-counterfeiting composition is disclosed, in addition to the composition in the above-mentioned composition, optionally, the anti-counterfeiting ink further comprises one or more components of offset printing base ink, gravure printing base ink, varnish or gloss oil; the anti-counterfeiting coating can also contain other resin components, such as one or more of polyester resin, polyether resin, vinyl chloride polymer and vinyl chloride-based copolymer, nitrocellulose resin, cellulose acetobutyrate or cellulose acetopropionate resin, maleic acid-based resin, polyamide, polyolefin, polyurethane resin, functionalized polyurethane resin, polyurethane alkyd resin, etc. In addition, the composition of the ink or coating can also be adjusted to make it suitable for inkjet printing or spraying.

[0127] In this aspect, the present application also provides a security mark based on the composition of <first aspect>, which can appear in the form of a liquid or a solution, or in the form of a dry substance of the anti-counterfeiting composition of the present application, and these marks can be independently selected from symbols, graphics, letters, words, numbers, logos, pictures and combinations thereof. In some preferred embodiments, it can be formed on any desired substrate by printing, printing or spraying, etc.

[0128] In this aspect, the present application also provides an anti-counterfeiting layer based on the composition of <first aspect>, in some specific embodiments, the anti-counterfeiting layer can be formed by spraying or coating with the aforementioned anti-counterfeiting composition; in some other specific embodiments, such anti-counterfeiting layer can be a resin layer containing quantum dot material, especially when there is a polymerizable component in the anti-counterfeiting composition, a crosslinked or non-crosslinked resin cured layer can be formed by light-induced polymerization, and under the action of the photoinitiator, the quantum dot material can be uniformly dispersed and fixed in the cured layer, preferably, the quantum dot material and the resin component have a covalent bond connection.

[0129] In addition, the present application also provides a security document or security article having a security marking or anti-counterfeiting layer based on the security marking composition of the present application on its surface or inside.

[0130] <Third aspect>

[0131] In the third aspect of the present application, a method for authenticating a security document or security article is provided, which is used to authenticate whether the security document or security article has the anti-counterfeiting composition or its dried product of the present application.

[0132] The authentication method comprises providing an article to be detected to authenticate whether the security marking or anti-counterfeiting layer of the article is formed by the security marking composition or its dried product of the present application.

[0133] Specifically, the authentication method comprises:

[0134] i) obtaining an article having a security marking or anti-counterfeiting layer;

[0135] ii) irradiating the security marking or anti-counterfeiting layer of the article with excitation light, wherein the wavelength of the excitation light is 254-395 nm, preferably 360-390 nm, and in some specific embodiments, the light irradiation power can be 5-20 W.

[0136] As for the light irradiation time, it is related to the luminescence characteristics or quenching characteristics of the quantum dot material in the anti-counterfeiting composition. Generally, the light irradiation time is sufficient to cause at least partial quenching of the quantum dot material. In some preferred embodiments, the light irradiation time can be no more than 200 s, preferably no more than 150 s, and more preferably no more than 120 s. It can be understood that if a shorter light irradiation time is sufficient to cause a change in the emission wavelength of the quantum dot material in the anti-counterfeiting composition due to the quenching effect, it is more advantageous to improve the convenience of detection.

[0137] Detecting whether the composition produces a change in the emission wavelength during the excitation light irradiation period or detecting the time when the composition produces a change in the emission wavelength during the excitation light irradiation period, and recording these characteristics or information, and further comparing these characteristics and information with standard information of the composition or its dried product based on the present application. As for the standard information, it can be obtained in advance or detected in advance by the authenticator according to the information provided by the supplier of the anti-counterfeiting composition of the present application.

[0138] As for the information for comparison, it can also be additional information obtained by changing the detection conditions (excitation conditions) and the like, for example:

[0139] ① excite the security marking to be detected (dry matter), record detection information F1; further irradiate with the same excitation light in the presence of additional solvent, and record detection information F2. Compare the information of F1 and / or F2 with standard information; or

[0140] ② excite the security marking to be detected (composition or dry matter thereof) in an oxygen-free atmosphere, record detection information F1; excite the security marking to be detected (composition or dry matter thereof) in an oxygen-containing atmosphere, record detection information F2. Compare the information of F1 and / or F2 with standard information.

[0141] Of course, the security features of the security composition according to the present application described above can also be encoded as desired based on the method provided by the present application, and the corresponding authentication method can be matched therewith.

[0142] In addition, the authentication method described above in the present application can be realized by means of various optical instruments and computer automatic detection, and the present application does not have special limitations on these instruments or software programs matched therewith.

[0143] Examples

[0144] The present application is further described below in conjunction with the drawings and examples.

[0145] <raw materials>

[0146] (quantum dots)

[0147] Quantum dot QD-1, laboratory synthesis: (CdSe), emission wavelength 630 nm.

[0148] Quantum dot QD-2, laboratory synthesis: (CdSe), emission wavelength 510 nm.

[0149] Quantum dot QD-3, laboratory synthesis: (CdSe), emission wavelength 450 nm.

[0150] Quantum dot QD-4, laboratory synthesis: (InP), emission wavelength 630 nm.

[0151] Quantum dot QD-5, laboratory synthesis: (InP), emission wavelength 510 nm.

[0152] Quantum dot QD-6, laboratory synthesis: (InP), emission wavelength 450 nm.

[0153] (polymerizable monomers)

[0154] Isobornyl acrylate, commercially available, analytical pure;

[0155] 1,6-hexanediol diacrylate, commercially available, analytical pure.

[0156] (solvent)

[0157] Chloroform, phenylcyclohexane, commercially available, analytical pure.

[0158] (initiator)

[0159] 1173: 2-hydroxy-2-methyl-1-phenyl-1-propanone, for short HMPP;

[0160] TPO: (2,4,6-trimethylbenzoyl)chloride, diphenyl phosphine oxide;

[0161] 184: 1-hydroxycyclohexyl phenyl ketone

[0162] <irradiation conditions>

[0163] temperature: 30°C;

[0164] excitation light wavelength: 365 nm;

[0165] power: 20 W

[0166] Examples 1 to 12 and Comparative Example 1

[0167] The compositions were prepared according to the following Table 1:

[0168] Table 1:

[0169]

[0170] Preparation process of examples and comparative examples

[0171] The quantum dots of different emission wavelengths were mixed in proportion, and the initiator was dissolved in the solvent (and monomer) in proportion. Then the initiator solution was added to the mixed quantum dots in proportion, and mixed uniformly. The obtained mixture was added dropwise to the surface of a cover glass, and irradiated. For an oxygen-free environment, the cover glass was placed in an oxygen-free environment for irradiation.

[0172] The compositions of Examples 1 to 12 and Comparative Example 1 were irradiated under the above irradiation conditions, and the color change was observed.

[0173] The results are shown in the following Table 2:

[0174] Table 2:

[0175]

[0176] Comparative Example 1 was irradiated under the above irradiation conditions, and the color change was observed. The results are shown in the following Table 3:

[0177] Table 3:

[0178] Aerobic conditions Anaerobic conditions No color change within 120 s of irradiation No color change within 120 s of irradiation ​

[0179] In the compositions of Example 1 to Example 12, above, under aerobic or anaerobic conditions, because the quenching times of the different kinds of quantum dots under irradiation conditions are different, the change in the distinguishable color (emission wavelength) occurs within the irradiation time.

[0180] Note that in Comparative Example 1, although different kinds of quantum dot materials were used in the composition, the composition did not show a difference in quenching time, and thus the change in the color of the composition was not observed.

[0181] Note that although the technical solutions of the present application are described with specific examples, those skilled in the art can understand that the present application should not be limited thereto.

[0182] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

[0183] Industrial applicability

[0184] The method provided by the present application is used as an anti-counterfeiting method or an anti-counterfeiting identification method.

Claims

1. A security composition, characterized in that, The composition comprises two or more quantum dot materials and a photoinitiator, and The emission wavelength and quenching time of the emission light generated by at least two of the quantum dot materials in the composition under the same excitation condition are different, wherein The emission wavelength of the emission light of each quantum dot material is in the range of 350-780 nm, and the emission light of the quantum dot material at least comprises fluorescence; The same excitation condition at least comprises the same wavelength of excitation light, and optionally, at least one of the following conditions is also the same: the atmosphere, the solvent atmosphere or the temperature condition during excitation, The photoinitiator is selected from one or more cleavage-type photoinitiators, which are photoinitiators that generate free radicals under light irradiation.

2. Composition according to claim 1, characterized in that In the composition, the emission wavelength and quenching time of the emission light generated by 2-10 quantum dot materials under the same excitation condition are different.

3. The composition according to claim 1 or 2, characterized in that, The difference in emission wavelength between the quantum dot materials under the same excitation condition is 15 nm or more; the difference in quenching time between the quantum dot materials under the same excitation condition is 0.5 s or more.

4. The composition according to claim 1 or 2, characterized in that, The composition further comprises one or more of a photopolymerizable monomer, a photopolymer active oligomer, a coupling agent, a solvent.

5. The composition according to claim 1 or 2, characterized in that, The emission light of the quantum dot material under the excitation condition comprises fluorescence, and optionally further comprises phosphorescence or delayed fluorescence.

6. The composition according to claim 1 or 2, characterized in that, The atmosphere includes an oxygen-containing atmosphere or an oxygen-free atmosphere; the solvent atmosphere includes an organic solvent or water; and the temperature condition is in the range of -30-60°C.

7. The composition according to claim 1 or 2, characterized in that, The emission wavelength or quenching time of the quantum dot material has at least one of the following responses: atmosphere response, solvent atmosphere response or temperature response.

8. A security ink or coating, characterized in that The ink or coating comprises the composition according to any one of claims 1-7.

9. An optically security layer characterized in that, The security layer comprises the composition according to any one of claims 1-7.

10. A method of forgery-proof coding, characterized in that The method comprises: Selecting or adjusting the types or contents of quantum dot materials in the composition according to any one of claims 1-7, wherein at least two of the quantum dot materials in the adjusted quantum dot materials generate emission light with different emission wavelengths and quenching times under the same excitation condition.

11. A method of forgery-proof authentication, characterized in that The method comprises: i) obtaining an article with a security mark or a security layer; ii) irradiating the security mark or the security layer of the article with excitation light, the wavelength of the excitation light being 254-395 nm; Detecting whether the security mark or the security layer generates a change in emission wavelength during the excitation light irradiation period or detecting the time when the security mark or the security layer generates a change in emission wavelength during the excitation light irradiation period, and comparing it with the standard information of the composition or its dried product according to any one of claims 1-7.

12. The method of claim 11, wherein, The step ii) is carried out under one or more different atmosphere, solvent atmosphere or temperature conditions.

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