Colorless fluorescent anti-forgery ink and preparation method thereof

Abstract

The invention relates to the technical field of colorless fluorescent ink, and particularly discloses colorless fluorescent anti-forgery ink and a preparation method thereof. The colorless fluorescent anti-forgery ink is prepared from the following raw materials: 30-50 parts of modified water-based acrylic resin, 15-20 parts of fluorescent pigment, 30-40 parts of water, 3-7 parts of a cosolvent, 0.5-1 part of a defoaming agent, 2-5 parts of a dispersing agent and 1-5 parts of a coalescing agent, the preparation method of the modified water-based acrylic resin comprises the following steps: S1, mixing an emulsifier with deionized water, then adding a mixed monomer, and heating and stirring to obtain a pre-emulsion; and S2, taking a part of the pre-emulsion, adding a part of the amount of an initiator, carrying out a heating reaction, adding vinyltriisopropoxysilane, the rare earth doped aluminosilicate sol, the remaining pre-emulsion and the initiator after the emulsion presents blue light, carrying out a heat preservation reaction, and after the reaction is finished, carrying out cooling and adjusting the pH value, thereby obtaining the blue light-emitting coating. According to the application, the stability of the fluorescent anti-counterfeiting effect of the colorless fluorescent anti-counterfeiting ink in an outdoor environment can be remarkably improved by applying the modified water-based acrylic resin.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of colorless fluorescent ink, more particularly, it relates to a colorless fluorescent anti-counterfeiting ink and a preparation method thereof. BACKGROUND

[0002] The colorless fluorescent ink is a kind of anti-counterfeiting printing material which is colorless itself but can emit bright fluorescence under ultraviolet light, also known as invisible ink. The composition of the colorless fluorescent ink is fluorescent pigment, which can emit visible light of 400-800 nm wavelength under 200-400 nm wavelength ultraviolet light. According to the excitation wavelength, it can be divided into two types of short wave (254 nm) and long wave (365 nm), and has the characteristics of transparent concealment. The ink is suitable for screen printing and intaglio printing process. During printing, the fluorescent crystal structure should be avoided to be damaged by the pressure of relief printing. Printing on rough paper or coated surface can optimize the invisible effect.

[0003] The fluorescent pigment belongs to functional luminescent pigment. The difference between the fluorescent pigment and general pigment is that when the external light (including ultraviolet light) is irradiated, it can absorb certain form of energy, excite photons, and release the absorbed energy in the form of low visible light, thereby producing different color fluorescence. Different color light combines to form an unusually bright color, and the luminescence phenomenon disappears when the light stops shining, so it is called fluorescent pigment. The fluorescent pigment can be divided into organic fluorescent pigment and inorganic fluorescent pigment. The organic fluorescent pigment is prepared by fully dispersing fluorescent dye (fluorescent body) in transparent and brittle resin (carrier). The color is determined by the fluorescent dye molecule. The inorganic fluorescent pigment is prepared by calcining the metal (zinc, chromium) sulfide or rare earth oxide with a small amount of active agent. It is colorless or light white. The fluorescent ink can be prepared by grinding the fluorescent pigment, high molecular resin binder, solvent and additives in a certain proportion. The water-based fluorescent ink is a fluorescent ink with water as the solvent. It combines the characteristics of water-based ink and fluorescent ink, and has the characteristics of environmental protection, safety and anti-counterfeiting. It is widely used in the industry.

[0004] According to the related technology in the above, the inventors believe that the durability of water-based ink is poorer than that of oily ink, especially in outdoor environments, which is frequently affected by sunlight, humid environment, temperature changes and other conditions, which can cause unstable fluorescent anti-counterfeiting effect.

[0005] Therefore, there is an urgent need to propose a scheme to solve the above technical problems. SUMMARY

[0006] In order to improve the stability of the fluorescent anti-counterfeiting effect of the water-based fluorescent ink in the outdoor environment, the present application provides a colorless fluorescent anti-counterfeiting ink and a preparation method thereof.

[0007] In a first aspect, the present application provides a colorless fluorescent anti-counterfeiting ink, which adopts the following technical scheme: A colorless fluorescent anti-counterfeiting ink is made from raw materials comprising the following weight parts: Modified water-based acrylic resin 30-50 parts; Fluorescent pigment 15-20 parts; Water 30-40 parts; Co-solvent 3-7 parts; Defoaming agent 0.5-1 part; Dispersant 2-5 parts; Film-forming aid 1-5 parts; The modified water-based acrylic resin is prepared by the following steps: S1, after mixing the emulsifier and deionized water, then adding the mixed monomers, heating and stirring to obtain a pre-emulsion; S2, take part of the pre-emulsion and add part of the initiator to react at elevated temperature, after the emulsion turns blue, add vinyl triisopropoxy silane, rare earth doped silico-alumina sol and the remaining pre-emulsion and initiator for heat preservation reaction, after the reaction is completed, cool down, adjust the pH, and obtain the modified water-based acrylic resin.

[0008] By adopting the above technical scheme, in the preparation of the modified water-based acrylic resin, the emulsifier can reduce the oil-water interfacial tension, so that the mixed monomers are uniformly dispersed in water to form a stable emulsion; deionized water as a reaction medium provides the aqueous environment required for free radical polymerization; the initiator decomposes to produce free radicals, triggering the chain polymerization reaction of monomer double bonds; and the vinyl triisopropoxy silane participates in the copolymerization of the mixed monomers, forming a three-dimensional Si-O-Si network structure through condensation, which not only resists ultraviolet chain degradation, but also inhibits water penetration, significantly improving weather resistance; at the same time, in the application process, the rare earth doped silico-alumina sol stabilizes the resin molecules through the coordination of rare earth elements, reduces the chain scission and photochemical degradation of resin molecules caused by ultraviolet light, and forms a physical barrier with the silico-alumina skeleton, reducing the permeability of oxygen and moisture, thereby significantly improving the weather resistance; in this way, when the vinyl triisopropoxy silane and the rare earth doped silico-alumina sol are used together, an organic-inorganic hybrid network can be formed, which has excellent synergistic effect, and has excellent resistance to frequent influences such as sunlight, humid environment and temperature changes in outdoor environment. Further applying the above obtained modified water-based acrylic resin to the colorless fluorescent anti-counterfeiting ink can significantly improve the fluorescent anti-counterfeiting effect stability of the colorless fluorescent anti-counterfeiting ink in outdoor environment.

[0009] Preferably, in the preparation of the modified water-based acrylic resin, the weight ratio of the emulsifier, deionized water, mixed monomers and initiator is (0.5-2.2):(30-50):(40-60):1.

[0010] By adopting the above technical scheme, the emulsifier is used to stabilize the pre-emulsion to prevent monomer aggregation, too low will cause the emulsion to be unstable, and too high will cause foam or film forming defects; the deionized water is used as a reaction medium and a dispersed phase, too low water amount will cause viscosity to rise and affect the flowability of the pre-emulsion, and too high water amount will reduce the solid content and prolong the drying time; the mixed monomers are the core of the polymer main chain, too low proportion will cause poor resin film forming property, and too high proportion will easily cause gelation; too much initiator will easily cause uneven molecular weight distribution, and too little initiator will cause incomplete reaction; and the emulsifier, the deionized water, the mixed monomers and the initiator in the above proportions can avoid the above defects while ensuring that the vinyl triisopropoxy silane and the rare earth doped silicoaluminoxane sol fully play a role, so that the modified water-based acrylic resin obtained finally has stable and good application quality, and the colorless fluorescent anti-counterfeiting ink obtained by using the modified water-based acrylic resin has excellent and stable weather resistance.

[0011] Preferably, in the preparation of the modified water-based acrylic resin, the weight ratio of the vinyl triisopropoxy silane, the rare earth doped silicoaluminoxane sol and the mixed monomers is (1-2): 1: (8-12).

[0012] By adopting the above technical scheme, the vinyl triisopropoxy silane is introduced into the resin main chain by copolymerization, and the excellent effect is brought about, but too high amount of the vinyl triisopropoxy silane will cause the stability of the pre-emulsion to decrease, and too low amount of the vinyl triisopropoxy silane will cause insufficient crosslinking effect; too low amount of the rare earth doped silicoaluminoxane sol will cause the functional effect brought about by the rare earth doped silicoaluminoxane sol to be difficult to bring about, and too high amount of the rare earth doped silicoaluminoxane sol will damage the polymer structure; and the vinyl triisopropoxy silane, the rare earth doped silicoaluminoxane sol and the mixed monomers in the above proportions have good synergistic compatibility when applied, and the compounding between the vinyl triisopropoxy silane and the rare earth doped silicoaluminoxane sol can bring about a good and significant improvement effect, so that a modified water-based acrylic resin with stable and good application quality is ensured to be obtained finally, and the colorless fluorescent anti-counterfeiting ink obtained finally also has excellent and stable weather resistance.

[0013] Preferably, the mixed monomers are composed of methyl methacrylate, butyl acrylate, acrylic acid and styrene in a weight ratio of (25-35): (9-11): 1: (8-10).

[0014] By adopting the technical scheme, methyl methacrylate is used as a hard monomer to dominate hardness and weather resistance; butyl acrylate is used to optimize flexibility and adhesion; acrylic acid is used as a functional monomer to form cross-linking points in polymerization and to improve emulsion stability and enhance water resistance; styrene can supplement the rigidity of methyl methacrylate and reduce raw material cost; and the mixed monomers of methyl methacrylate, butyl acrylate, acrylic acid and styrene used in the above weight ratio can balance the mechanical properties, weather resistance and processing stability of the resin, so that a modified water-based acrylic resin with stable application quality and better performance is obtained, and finally a colorless fluorescent anti-counterfeiting ink with excellent quality is obtained.

[0015] Preferably, the rare earth-doped silicoaluminophosphate sol is prepared by the following steps: The rare earth chloride is doped into the aluminum nitrate solution, and then added into the sodium silicate solution. After adjusting the pH, α-methacrylic acid is added, and the rare earth-doped silicoaluminophosphate sol is obtained after stirring.

[0016] By adopting the technical scheme, the rare earth chloride provides rare earth ions, the aluminum nitrate provides aluminum ions, the rare earth ions are embedded into the aluminum salt precursor through coordination to form a rare earth-aluminum composite structure; the sodium silicate is used as a silicon source to hydrolyze to generate silicon hydroxyl groups and react with the rare earth-aluminum composite to form a silicoaluminophosphate network skeleton; after adjusting the pH, the α-methacrylic acid is added, the carboxyl groups of the α-methacrylic acid are coordinated with the rare earth or aluminum ions to form an organic-inorganic hybrid structure, and the polymerization active sites are introduced to copolymerize with acrylate to provide reaction sites for in-situ cross-linking; thus, the rare earth-doped silicoaluminophosphate sol can fully play its role in application and fully cooperate with the vinyl triisopropoxy silane to ensure that the colorless fluorescent anti-counterfeiting ink obtained by modifying the water-based acrylic resin has excellent weather resistance and better stability of the fluorescent anti-counterfeiting effect in outdoor environments.

[0017] Preferably, the concentration of the aluminum nitrate solution is 20-30wt%, the concentration of the sodium silicate solution is 10-20wt%, and the weight ratio of the rare earth chloride, the aluminum nitrate solution, the sodium silicate solution and the α-methacrylic acid is (1-3):(4-6):(8-12):1.

[0018] By adopting the technical scheme, the concentration of the aluminum nitrate solution is 20-30wt% to ensure sufficient supply of aluminum ions, and the concentration of the sodium silicate solution is 10-20wt% to effectively control the hydrolysis rate; on this basis, the above proportions of the rare earth chloride, the aluminum nitrate solution, the sodium silicate solution and the α-methacrylic acid are selected for use to optimize the structural stability, doping efficiency and functional enhancement of the sol, so that the rare earth-doped silicoaluminophosphate sol can play a better corresponding role effect.

[0019] Preferably, the rare earth chloride is composed of lanthanum chloride, samarium chloride and dysprosium chloride in a weight ratio of 1:(1-2):(1.5-2.5).

[0020] By adopting the technical scheme, lanthanum ions form a coordination bond with the resin main chain, inhibit molecular chain rupture at high temperature, and delay thermal oxidative degradation; samarium ions can protect C-C bonds in the acrylic resin from photodegradation; dysprosium ions can catalyze oxygen reduction reactions in the silicoaluminoxane network and inhibit oxygen and moisture penetration; when the rare earth chloride composed of lanthanum chloride, samarium chloride and dysprosium chloride in the above ratio is used, the ion doping, structure strengthening and energy management effects brought by the three are utilized, so that the modified water-based acrylic resin obtained by applying the rare earth-doped silicoaluminoxane sol achieves long-term outdoor stability in the colorless fluorescent anti-counterfeiting ink.

[0021] In a second aspect, the application provides a preparation method of a colorless fluorescent anti-counterfeiting ink, which adopts the following technical scheme: A preparation method of a colorless fluorescent anti-counterfeiting ink, comprising the following steps: (1) preparing raw materials including modified water-based acrylic resin, fluorescent pigment, water, cosolvent, defoaming agent, dispersant and film-forming aid according to the proportion; (2) uniformly mixing the modified water-based acrylic resin and the fluorescent pigment in step (1), then continuously stirring and mixing after adding water and cosolvent, and finally continuously stirring after adding the defoaming agent, the dispersant and the film-forming aid, to obtain the colorless fluorescent anti-counterfeiting ink.

[0022] By adopting the technical scheme, the preparation method is simple to operate, the raw materials are added step by step, which not only facilitates quality control during preparation, but also enables the raw materials to be fully mixed and interact with each other, so that the colorless fluorescent anti-counterfeiting ink with excellent quality and stability is obtained, and the whole is also suitable for large-scale industrial production.

[0023] In summary, the application has the following beneficial effects: In the preparation of the modified water-based acrylic resin, the application uses vinyl triisopropoxysilane and rare earth-doped silicoaluminoxane sol, and forms an organic-inorganic hybrid network in the preparation by the combination of the two, which can bring excellent synergistic effects, and has excellent resistance to frequent influences such as sunlight, humid environment and temperature changes in outdoor environments; therefore, when the modified water-based acrylic resin is applied to the colorless fluorescent anti-counterfeiting ink, the fluorescent anti-counterfeiting effect stability of the colorless fluorescent anti-counterfeiting ink in outdoor environments can be significantly improved. DETAILED DESCRIPTION

[0024] The application will be further described in detail below in combination with preparation examples, examples and comparative examples.

[0025] The raw materials used in the preparation examples, examples and comparative examples of the present application are commercially available, unless otherwise specified.

[0026] The fluorescent pigment is inorganic ultraviolet white fluorescent powder YDS-BSF from Shenzhen Yaodesheng Technology Co., Ltd. The cosolvent is isopropyl alcohol. The defoaming agent is TEGO AIREX 902W defoaming agent from Wincell. The dispersing agent is BLN-3178 water-based dispersing agent from Bolinuo. The film-forming aid is dipropylene glycol butyl ether.

[0027] Preparation examples of raw materials and / or intermediates Preparation Example 1 A rare earth-doped silicoaluminoxane sol is prepared by the following steps: The rare earth chloride is doped into the aluminum nitrate solution, then added to the sodium silicate solution, and after adjusting the pH to 5, α-methacrylic acid is added. After stirring, a rare earth-doped silicoaluminoxane sol is obtained.

[0028] Note: In the above operation, the concentration of the aluminum nitrate solution is 25wt%, the concentration of the sodium silicate solution is 15wt%, and the weight ratio of the rare earth chloride, the aluminum nitrate solution, the sodium silicate solution and the α-methacrylic acid is 2:5:10:1. The rare earth chloride is composed of lanthanum chloride, samarium chloride and dysprosium chloride in a weight ratio of 1:1.5:2.

[0029] Preparation Example 2 A rare earth-doped silicoaluminoxane sol, different from Preparation Example 1, is that the concentration of the aluminum nitrate solution is 20wt%, the concentration of the sodium silicate solution is 10wt%, and the weight ratio of the rare earth chloride, the aluminum nitrate solution, the sodium silicate solution and the α-methacrylic acid is 3:6:12:1.

[0030] Preparation Example 3 A rare earth-doped silicoaluminoxane sol, different from Preparation Example 1, is that the concentration of the aluminum nitrate solution is 30wt%, the concentration of the sodium silicate solution is 20wt%, and the weight ratio of the rare earth chloride, the aluminum nitrate solution, the sodium silicate solution and the α-methacrylic acid is 1:4:8:1.

[0031] Preparation Example 4 A rare earth-doped silicoaluminoxane sol, different from Preparation Example 1, is that the rare earth chloride is composed of lanthanum chloride, samarium chloride and dysprosium chloride in a weight ratio of 1:1:1.5.

[0032] Preparation Example 5 A rare earth-doped silicoaluminoxane sol, different from Preparation Example 1, is that the rare earth chloride is composed of lanthanum chloride, samarium chloride and dysprosium chloride in a weight ratio of 1:2:2.5.

[0033] Preparation Example 6 A rare earth doped silicoaluminate sol, which is different from Preparation Example 1 in that lanthanum chloride and samarium chloride are not used in the rare earth chloride.

[0034] Preparation Example 7 A rare earth doped silicoaluminate sol, which is different from Preparation Example 1 in that lanthanum chloride and gadolinium chloride are not used in the rare earth chloride.

[0035] Preparation Example 8 A rare earth doped silicoaluminate sol, which is different from Preparation Example 1 in that samarium chloride and gadolinium chloride are not used in the rare earth chloride.

[0036] Preparation Example 9 A modified water-based acrylic resin is prepared by the following steps: S1, after mixing the emulsifier and deionized water, adding the mixed monomers, heating and stirring to obtain a pre-emulsion; S2, 40% by weight of the pre-emulsion is added to 30% by weight of the initiator to heat to 75°C for reaction. After the emulsion turns blue, vinyl triisopropoxy silane, rare earth doped silicoaluminate sol and the remaining pre-emulsion and initiator are added dropwise within 2h, then 80°C is maintained for 1h. After the reaction is completed, the temperature is cooled to 40°C, the pH is adjusted to 7, and the modified water-based acrylic resin is obtained.

[0037] Note: In the above operation, the weight ratio of emulsifier, deionized water, mixed monomers and initiator is 1.35:40:50:1. The weight ratio of vinyl triisopropoxy silane, rare earth doped silicoaluminate sol and mixed monomers is 1.5:1:10. The mixed monomers are composed of methyl methacrylate, butyl acrylate, acrylic acid and styrene in a weight ratio of 30:10:1:9. The rare earth doped silicoaluminate sol is obtained in Preparation Example 1. The emulsifier is sodium dodecyl benzene sulfonate. The initiator is potassium persulfate.

[0038] Preparation Example 10 A modified water-based acrylic resin, which is different from Preparation Example 9 in that the weight ratio of emulsifier, deionized water, mixed monomers and initiator is 0.5:30:40:1.

[0039] Preparation Example 11 A modified water-based acrylic resin, which is different from Preparation Example 9 in that the weight ratio of emulsifier, deionized water, mixed monomers and initiator is 2.2:50:60:1.

[0040] Preparation Example 12 A modified waterborne acrylic resin, except that the weight ratio of vinyl triisopropoxysilane, rare earth doped silicoaluminoxy sol and mixed monomers is 1 : 1 : 8, from Preparation Example 9.

[0041] Preparation Example 13 A modified waterborne acrylic resin, except that the weight ratio of vinyl triisopropoxysilane, rare earth doped silicoaluminoxy sol and mixed monomers is 2 : 1 : 12, from Preparation Example 9.

[0042] Preparation Example 14 A modified waterborne acrylic resin, except that the mixed monomers consist of methyl methacrylate, butyl acrylate, acrylic acid and styrene in a weight ratio of 25 : 9 : 1 : 8, from Preparation Example 9.

[0043] Preparation Example 15 A modified waterborne acrylic resin, except that the mixed monomers consist of methyl methacrylate, butyl acrylate, acrylic acid and styrene in a weight ratio of 35 : 11 : 1 : 10, from Preparation Example 9.

[0044] Preparation Example 16 A modified waterborne acrylic resin, except that the rare earth doped silicoaluminoxy sol is obtained in Preparation Example 2, from Preparation Example 9.

[0045] Preparation Example 17 A modified waterborne acrylic resin, except that the rare earth doped silicoaluminoxy sol is obtained in Preparation Example 3, from Preparation Example 9.

[0046] Preparation Example 18 A modified waterborne acrylic resin, except that the rare earth doped silicoaluminoxy sol is obtained in Preparation Example 4, from Preparation Example 9.

[0047] Preparation Example 19 A modified waterborne acrylic resin, except that the rare earth doped silicoaluminoxy sol is obtained in Preparation Example 5, from Preparation Example 9.

[0048] Preparation Example 20 A modified waterborne acrylic resin, except that the rare earth doped silicoaluminoxy sol is obtained in Preparation Example 6, from Preparation Example 9.

[0049] Preparation Example 21 A modified waterborne acrylic resin, except that the rare earth doped silicoaluminoxy sol is obtained in Preparation Example 7, from Preparation Example 9.

[0050] Preparation Example 22 A modified water-based acrylic resin, which is different from Preparation Example 9 in that the rare earth-doped silicoaluminophosphate sol is obtained in Preparation Example 8.

[0051] Preparation Example 23 A modified water-based acrylic resin, which is different from Preparation Example 9 in that the vinyl triisopropoxysilane is not used in the preparation raw materials.

[0052] Preparation Example 24 A modified water-based acrylic resin, which is different from Preparation Example 9 in that the rare earth-doped silicoaluminophosphate sol is not used in the preparation raw materials.

[0053] Preparation Example 25 A modified water-based acrylic resin, which is different from Preparation Example 9 in that the vinyl triisopropoxysilane and the rare earth-doped silicoaluminophosphate sol are not used in the preparation raw materials.

[0054] Example Example 1 A colorless fluorescent anti-counterfeiting ink, the raw materials used for its preparation and their corresponding weight parts are shown in Table 1, and is prepared by the following steps: (1) Prepare raw materials containing modified water-based acrylic resin, fluorescent pigment, water, cosolvent, defoamer, dispersant and film-forming aid according to the ratio; (2) After the modified water-based acrylic resin and fluorescent pigment of step (1) are uniformly mixed, water and cosolvent are added and continue to be stirred and mixed, and finally defoamer, dispersant and film-forming aid are added and continue to be stirred, to obtain a colorless fluorescent anti-counterfeiting ink.

[0055] Note: In the above operation, the modified water-based acrylic resin is obtained in Preparation Example 9.

[0056] Example 2-3 A colorless fluorescent anti-counterfeiting ink, which is different from Example 1 in that the raw materials used for its preparation and their corresponding weight parts are shown in Table 1.

[0057] Table 1 Raw materials used for preparation and their corresponding weight parts (parts / kg) of Examples 1-3 Raw materials Example 1 Example 2 Example 3 Modified water-based acrylic resin 40 30 50 Fluorescent pigment 17.5 15 20 Water 35 30 40 Co-solvent 5 3 7 Defoaming agent 0.75 0.5 1 Dispersant 3.5 2 5 Film-forming aid 3 1 5 Example 4 A colorless fluorescent anti-counterfeiting ink, which is different from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 10.

[0058] Example 5 A colorless fluorescent anti-counterfeiting ink, which is different from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 11.

[0059] Example 6 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 12.

[0060] Example 7 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 13.

[0061] Example 8 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 14.

[0062] Example 9 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 15.

[0063] Example 10 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 16.

[0064] Example 11 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 17.

[0065] Example 12 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 18.

[0066] Example 13 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 19.

[0067] Example 14 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 20.

[0068] Example 15 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 21.

[0069] Example 16 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained in Preparation Example 22.

[0070] Comparative Example Comparative Example 1 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained from Preparation Example 23.

[0071] Comparative Example 2 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained from Preparation Example 24.

[0072] Comparative Example 3 A colorless fluorescent anti-counterfeiting ink, which differs from Example 1 in that the modified water-based acrylic resin is obtained from Preparation Example 25.

[0073] Performance detection test Test samples: The colorless fluorescent anti-counterfeiting inks obtained in Examples 1-16 were selected as test samples 1-16, and the colorless fluorescent anti-counterfeiting inks obtained in Comparative Examples 1-3 were selected as control samples 1-3.

[0074] Test method: The colorless fluorescent anti-counterfeiting ink was used to make a standard sample according to the requirements in Standard GB / T 17001.1-2024; The initial fluorescence intensity of the standard sample under excitation at a specific ultraviolet wavelength was measured using a spectrophotometer, denoted as A; Then the same standard sample was sequentially tested as follows: (1) Temperature change resistance test: The standard sample was placed in a high-low temperature alternating test chamber, the initial temperature was 25°C, first increased to 100°C at a rate of 2°C / min, maintained for 5 min, then decreased to -10°C at a rate of 1°C / min and maintained for 3 min, then increased to 25°C at a rate of 1.5°C / min, denoted as 1 cycle; 20 cycles were continuously performed.

[0075] (2) Hot water resistance test: The standard sample was immersed in 80°C hot water under water bath conditions for 30 min, and then taken out and dried.

[0076] (3) Sunlight resistance test: The standard sample was placed in a sunlight simulator, the sunlight simulator used a SZl500 type xenon arc lamp as the light source, the power was 2000W, the radiation spectrum range covered 300-800nm, simulating full spectrum sunlight, the irradiance output value was 0.95W / m 2 , the test environment relative humidity was 65%, the test environment temperature was 35°C, and the sunlight duration was 72h.

[0077] Then, the fluorescence intensity of the standard sample after the above tests was measured using a spectrophotometer under excitation at a specific ultraviolet wavelength, denoted as B; Finally, the fluorescence intensity loss rate was calculated, fluorescence intensity loss rate = (A-B) / A, and the smaller the fluorescence intensity loss rate, the better the stability of the water-based fluorescent ink in outdoor environment.

[0078] After the above tests were performed on the test samples 1-16 and the control samples 1-3, the test results were correspondingly recorded in Table 2.

[0079] Table 2 Test results of test samples 1-16 and control samples 1-3 Sample Fluorescent intensity loss rate (%) Test sample 1 8.52 Test sample 2 8.67 Test sample 3 8.61 Test sample 4 8.56 Test sample 5 8.59 Test sample 6 8.65 Test sample 7 8.63 Test sample 8 8.55 Test sample 9 8.58 Test sample 10 8.64 Test sample 11 8.62 Test sample 12 8.57 Test sample 13 8.60 Test sample 14 9.23 Test sample 15 9.48 Test sample 16 9.35 Control sample 1 14.04 Control sample 2 14.70 Control sample 3 18.17 As can be seen from the combination of Example 1 and Comparative Examples 1-3 and Table 2, the use of vinyl triisopropoxysilane and rare earth-doped silicoaluminate sol in the preparation of modified water-based acrylic resin can significantly improve the fluorescence anti-counterfeiting effect stability of colorless fluorescent anti-counterfeiting ink in outdoor environment, and the fluorescence intensity loss rate obtained by the above test is also significantly reduced. At the same time, if only one of the vinyl triisopropoxysilane and the rare earth-doped silicoaluminate sol is used in the preparation of the modified water-based acrylic resin, although the corresponding effect can be improved, the sum of the improvement effects brought by the two alone is far less than the improvement effect brought by the combination of the two. Therefore, the combination of vinyl triisopropoxysilane and rare earth-doped silicoaluminate sol in the preparation of modified water-based acrylic resin can bring a significant improvement effect of 1+1>2.

[0080] As can be seen from the combination of Example 1 and Examples 12-13 and Table 2, the use of rare earth chlorides composed of lanthanum chloride, samarium chloride and dysprosium chloride in the above proportions can obtain rare earth-doped silicoaluminate sol with excellent and stable application quality, and the modified water-based acrylic resin prepared therefrom can exhibit excellent and stable weather resistance when applied to colorless fluorescent anti-counterfeiting ink. In combination with Examples 14-16 and Table 2, it can be seen that if any one of lanthanum chloride, samarium chloride and dysprosium chloride is used alone as a rare earth chloride, the rare earth-doped silicoaluminate sol obtained therefrom has a fluorescence intensity loss rate obtained by the above test when the modified water-based acrylic resin prepared therefrom is applied to colorless fluorescent anti-counterfeiting ink, which is not as excellent as the product performance obtained by the combination of lanthanum chloride, samarium chloride and dysprosium chloride. Therefore, the combination of lanthanum chloride, samarium chloride and dysprosium chloride can bring better and more excellent effects.

[0081] The specific embodiments are merely an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A colourless fluorescent security ink, characterised in that, Prepared from raw materials comprising the following parts by weight: Modified water-based acrylic resin 30-50 parts; Fluorescent pigment 15-20 parts; Water 30-40 parts; Co-solvent 3-7 parts; Defoaming agent 0.5-1 part; Dispersant 2-5 parts; Film forming aid 1-5 parts; The modified water-based acrylic resin is prepared by the following steps: S1, after mixing the emulsifier and deionized water, then adding the mixed monomer, heating and stirring to obtain a pre-emulsion; S2, take part of the pre-emulsion, add part of the initiator for temperature rise reaction, after the emulsion shows blue light, add vinyl triisopropoxy silane, rare earth doped silico-alumina sol and the remaining pre-emulsion, initiator for heat preservation reaction, after reaction, cooling, adjusting pH, to obtain the modified water-based acrylic resin.

2. The colorless fluorescent security ink according to claim 1, characterized in that: In the preparation of the modified water-based acrylic resin, the weight ratio of emulsifier, deionized water, mixed monomer and initiator is (0.5-2.2):(30-50):(40-60):

1.

3. The colorless fluorescent security ink according to claim 1, characterized in that: In the preparation of the modified water-based acrylic resin, the weight ratio of vinyl triisopropoxy silane, rare earth doped silico-alumina sol and mixed monomer is (1-2):1:(8-12).

4. The colorless fluorescent security ink according to claim 1, characterized in that: The mixed monomer is composed of methyl methacrylate, butyl acrylate, acrylic acid and styrene in a weight ratio of (25-35):(9-11):1:(8-10).

5. The colorless fluorescent security ink according to claim 1, wherein: The rare earth doped silico-alumina sol is prepared by the following steps: Take the rare earth chloride doped into the aluminum nitrate solution, then add to the sodium silicate solution, adjust the pH, then add α-methyl acrylic acid, stir to obtain the rare earth doped silico-alumina sol.

6. The colorless fluorescent security ink according to claim 5, characterized in that: The concentration of the aluminum nitrate solution is 20-30wt%, the concentration of the sodium silicate solution is 10-20wt%, and the weight ratio of rare earth chloride, aluminum nitrate solution, sodium silicate solution and α-methyl acrylic acid is (1-3):(4-6):(8-12):

1.

7. The colorless fluorescent security ink according to claim 5, wherein: The rare earth chloride is composed of lanthanum chloride, samarium chloride and dysprosium chloride in a weight ratio of 1:(1-2):(1.5-2.5).

8. A process for the preparation of the colourless fluorescent security ink as claimed in claim 1, characterized in that: Including the following steps: (1) Prepare raw materials containing modified water-based acrylic resin, fluorescent pigment, water, co-solvent, defoaming agent, dispersant and film forming aid according to the proportion; (2) Mix the modified water-based acrylic resin and fluorescent pigment of step (1) uniformly, then add water and co-solvent and continue to stir and mix, finally add defoaming agent, dispersant and film forming aid and continue to stir, to prepare colorless fluorescent anti-counterfeiting ink.