Near-infrared absorption invisible UV inkjet ink and preparation method thereof

Abstract

The invention relates to the technical field of anti-counterfeiting ink-jet ink, in particular to near-infrared absorption invisible UV ink-jet ink and a preparation method thereof.The ink-jet ink comprises anti-counterfeiting color paste, a photoinitiator, auxiliaries and a stabilizer; the anti-counterfeiting color paste is composed of an infrared absorption pigment, C.I pigment white, a leveling agent, a surfactant and an active monomer. The active monomer is composed of an active monomer A, an active monomer B and an active monomer; the active monomer A is modified tetrahydrofurfuryl acrylate; the active monomer B is at least one of 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate and triethylene glycol diacrylate; and the active monomer C is trimethylolpropane trimethacrylate. The auxiliary agent is silane modified nano silicon dioxide. Through the synergistic effect of the components, the wear resistance, hardness and adhesive force of the near-infrared absorption invisible UV ink-jet ink are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of anti-counterfeiting inkjet ink, and in particular to a near-infrared absorbing invisible UV inkjet ink and a preparation method thereof. Background Art

[0002] Printing anti-counterfeiting labels on product packaging materials using digital printing can strengthen product traceability management. Anti-counterfeiting labels in the prior art are generally visual labels. Once a product is put on the market, consumers can see what the anti-counterfeiting label is and where it is placed on the product. It is easy to be counterfeited. Invisible anti-counterfeiting fluorescent ink is an ink that is colorless and invisible under ordinary light after printing. The printed anti-counterfeiting content is only clearly visible under a specific wavelength environment.

[0003] Near infrared light (NIR) has a certain degree of penetration, and its absorption and reflection characteristics on certain materials are different from those of visible light. In the field of anti-counterfeiting and security printing, the use of near infrared absorption characteristics to detect invisible ink has the advantages of being difficult to detect and the detection equipment is relatively portable.

[0004] Some invisible inks currently on the market may have problems such as insufficient stability, poor compatibility with inkjet printing systems, or unsatisfactory near-infrared absorption. For example, some invisible inks are prone to deterioration during storage, resulting in loss of their invisible effect; or they are prone to clogging the nozzle during inkjet printing, affecting printing quality and production efficiency.

[0005] UV inkjet ink is a type of ink that is cured by ultraviolet light (UV). Compared with traditional water-based or solvent-based inks, it has the advantages of fast curing speed, environmental protection (low volatile organic compound emissions), and wear resistance. It has been increasingly widely used in industrial printing, packaging printing and other fields.

[0006] In the prior art, for example, patent document CN108892999A discloses a low-viscosity, fast-curing UV inkjet ink and a preparation method thereof, comprising 1-10 parts of a coloring pigment, 5-25 parts of a modified epoxy acrylate, 3-10 parts of a pure acrylic resin, 5-15 parts of DPHA, 5-15 parts of TMPTA, 20-40 parts of THFA, 5-20 parts of isobornyl acrylate, 5-20 parts of triethylene glycol divinyl ether, 1-13 parts of a photoinitiator, and 0.5-5 parts of an auxiliary agent; the curing rate of the inkjet ink is relatively fast, but the wear resistance needs to be further improved.

[0007] Therefore, according to the above-mentioned related technologies, it is urgent to develop a near-infrared absorbing invisible UV inkjet ink and a preparation method thereof. Summary of the invention

[0008] In view of this, the object of the present invention is to provide a near-infrared absorbing invisible UV inkjet ink and a preparation method thereof, so as to solve the problems of poor abrasion resistance and slow curing speed of invisible inkjet ink in the prior art.

[0009] Based on the above object, the present invention provides a near-infrared absorbing invisible UV inkjet ink and a preparation method thereof.

[0010] A near-infrared absorbing invisible UV inkjet ink, comprising the following raw materials in parts by mass: 25-32 parts of anti-counterfeiting color paste, 3.7-5.5 parts of photoinitiator, 1.1-1.6 parts of auxiliary agent, 1-2 parts of stabilizer.

[0011] Further, the anti-counterfeiting color paste is prepared from an infrared absorbing pigment, C.I. Pigment White, a leveling agent, a surfactant and a reactive monomer in a mass ratio of 12-18:3-5:3.2-4:2-3.5:63-75.

[0012] Further, the reactive monomer is obtained by mixing reactive monomer A, reactive monomer B and reactive monomer C in a mass ratio of 15-22:7-13:3-6.

[0013] Further, reactive monomer A is modified tetrahydrofurfuryl acrylate.

[0014] Further, reactive monomer B is at least one of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, and triethylene glycol diacrylate.

[0015] Further, reactive monomer C is trimethylolpropane trimethacrylate.

[0016] Further, the modified tetrahydrofurfuryl acrylate is prepared by reacting maleic anhydride with tetrahydrofurfuryl acrylate.

[0017] Further, the photoinitiator is obtained by mixing photoinitiator A and photoinitiator B in a mass ratio of 7-13:5-8.

[0018] Further, photoinitiator A is any one of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide TP0 and 2,4-diethylthioxanthone.

[0019] Further, photoinitiator B is 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone.

[0020] Further, the auxiliary agent is modified nano-silica.

[0021] Further, the modified nano-silica is prepared by reacting nano-silica with a silane coupling agent.

[0022] Furthermore, the preparation method of the modified tetrahydrofurfuryl acrylate is as follows: Add tetrahydrofurfuryl acrylate to the methanol solution. After stirring evenly, add maleic anhydride, heat to 70 - 85 °C while stirring, then add azobisisobutyronitrile, continue the reaction for 45 - 65 min, and then conduct vacuum drying to obtain the modified tetrahydrofurfuryl acrylate.

[0023] Furthermore, the dosage ratio of methanol, tetrahydrofurfuryl acrylate, maleic anhydride, and azobisisobutyronitrile is (20 - 28) mL : (5 - 8) g : (7 - 10) g : (0.5 - 1) g.

[0024] Furthermore, the temperature during vacuum drying is 78 - 85 °C and the time is 20 - 30 min.

[0025] Furthermore, the preparation method of the modified nano - silica is as follows: Disperse nano - silica in a mixed solution of deionized water and absolute ethanol, then add a silane coupling agent, stir and react at 60 - 70 °C for 4 - 6 h, filter, wash, and dry to obtain the modified nano - silica.

[0026] Furthermore, the mass ratio of nano - silica, deionized water, absolute ethanol, and the silane coupling agent is (11 - 15) : (300 - 380) : (45 - 58) : (10 - 20).

[0027] Furthermore, the particle size of the nano - silica is 2 - 7 nm.

[0028] Furthermore, the silane coupling agent is a mixture of an amino - silane coupling agent and a vinyl - silane coupling agent.

[0029] Furthermore, the mass ratio of the amino - silane coupling agent and the vinyl - silane coupling agent is (1 - 2) : (1 - 2).

[0030] Furthermore, the preparation method of the anti - counterfeiting color paste is as follows: Mix the infrared - absorbing pigment, C.I. Pigment White, leveling agent, surfactant, and reactive monomer evenly, grind to make the particle size of the infrared - absorbing pigment ≤ 50 nm, and conduct fine filtration using a filter element with a fineness ≤ 0.22 μm to obtain the anti - counterfeiting color paste.

[0031] Furthermore, the surfactant is BYK - 3760 with a mass fraction of 0.5%.

[0032] Furthermore, the stabilizer is at least one of hydroxyphenyltriazine, hydroxyphenylbenzotriazole, benzophenone, N,N’ - oxalyldianiline, cyanoacrylate, and salicylate.

[0033] Furthermore, the infrared absorption pigment is at least one of composite tungsten oxide and lanthanum hexaboride.

[0034] Furthermore, the composite tungsten oxide is preferably cesium tungsten oxide.

[0035] A preparation method of a near-infrared absorption invisible UV inkjet ink includes the following steps: Mix the anti-counterfeiting color paste, photoinitiator, auxiliary agent, stabilizer and solvent evenly, and obtain the near-infrared absorption invisible UV inkjet ink after grinding and filtering.

[0036] Furthermore, the rotation speed during grinding is 1200 - 1800 r / min, and the grinding time is 15 - 20 min.

[0037] Furthermore, the pore diameter during filtering is 0.5 - 1 μm.

[0038] Advantages of the present invention: (1) In the technical solution of the present invention, the active monomer A is modified tetrahydrofurfuryl acrylate, and an anhydride group is grafted on the tetrahydrofurfuryl acrylate, which can improve the compatibility of the copolymer after polymerization of the infrared absorption pigment and the active monomer, and improve the dispersion stability of the infrared absorption pigment, avoiding the problem of loss of the invisible effect during long-term storage. The active monomer of the present invention is composed of active monomer A, active monomer B and active monomer C. The number of carbon-carbon double bond functional groups of the three active monomers is different, significantly improving the crosslinking density, thereby further improving the stability of the infrared absorption pigment and making it not easy to precipitate.

[0039] (2) In the technical solution of the present invention, amino-silane coupling agent and vinyl-silane coupling agent are grafted on the nano-silica. Among them, the amino group can react with the anhydride group, and the vinyl group can participate in the polymerization reaction. The nano-silica serves as a crosslinking point, significantly improving the crosslinking density; the nano-silica has high hardness and wear resistance, which can improve the wear resistance of the ink. Specific embodiments

[0040] To make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0041] The sources and properties of some raw materials used in the present invention are as follows: Cesium tungsten oxide was purchased from Xiamen Zhongwu Online Technology Co., Ltd.; lanthanum hexaboride was purchased from Nangong Xingjiu New Material Technology Co., Ltd.; C.I. Pigment White was purchased from Hubei Chengfeng Chemical Co., Ltd.; 1,6 - hexanediol diacrylate was purchased from Shanghai Macklin Biochemical Co., Ltd.; dipropylene glycol diacrylate was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd.; tetrahydrofurfuryl acrylate was purchased from Shanghai Macklin Biochemical Co., Ltd.; maleic anhydride was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; trimethylolpropane trimethacrylate was purchased from Shandong Haoyao New Material Co., Ltd.; diphenyl(2,4,6 - trimethylbenzoyl)phosphine oxide TP0 was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; 2,4 - diethylthioxanthone was purchased from Wuhan Yuancheng Gongchuang Technology Co., Ltd.; 2 - benzyl - 2 - dimethylamino - 1 - (4 - morpholinophenyl)butanone was purchased from Wuhan Hongde Yuexin Pharmaceutical Technology Co., Ltd.; nano - silica was purchased from Shanghai Chaowei Nano Technology Co., Ltd.; leveling agent BYK 333 was purchased from Guangzhou Nantai Chemical Co., Ltd.; BYK - 3760 was purchased from Guangzhou Situlai Chemical Co., Ltd.

[0042] Example 1: A preparation method of a near - infrared absorbing invisible UV inkjet ink, comprising the following steps: S1. Add 5 g of tetrahydrofurfuryl acrylate to 20 mL of methanol solution, stir evenly, then add 7 g of maleic anhydride, heat to 70 °C while stirring, then add 0.5 g of azobisisobutyronitrile, continue to react for 45 min, and then vacuum dry at 78 °C for 20 min to obtain modified tetrahydrofurfuryl acrylate; S2. Disperse 11 g of nano - silica in a mixed solution of 300 g of deionized water and 58 g of absolute ethanol, then add 10 g of silane coupling agent (5 g of KH550 and 5 g of KH570), stir and react at 60 °C for 4 h, filter, wash, and dry to obtain modified nano - silica; S3. Mix 7 g of diphenyl(2,4,6 - trimethylbenzoyl)phosphine oxide TP0 with 5 g of 2 - benzyl - 2 - dimethylamino - 1 - (4 - morpholinophenyl)butanone to obtain a photoinitiator; then mix 7 g of 1,6 - hexanediol diacrylate, 15 g of modified tetrahydrofurfuryl acrylate, and 3 g of trimethylolpropane trimethacrylate to obtain active monomers; S4. Mix 12 g of cesium tungsten oxide, 3 g of C.I. Pigment White, 3.2 g of BYK 333, 2 g of BYK - 3760 with a mass fraction of 0.5%, and 63 g of active monomers evenly, grind to make the particle size of the infrared - absorbing pigment ≤50 nm, and finely filter with a filter element with a fineness ≤0.22 μm to obtain an anti - counterfeiting color paste; S5. Mix 25 g of anti-counterfeiting color paste, 3.7 g of photoinitiator, 1.1 g of modified nano-silica, 1 g of hydroxyphenyltriazine and 40 g of isopropanol evenly, grind for 15 min at a rotation speed of 1200 r / min, and the pore size is 0.5 μm during filtration to obtain near-infrared absorption invisible UV inkjet ink.

[0043] Example 2: A preparation method of near-infrared absorption invisible UV inkjet ink, comprising the following steps: S1. Add 6 g of tetrahydrofurfuryl acrylate to 23 mL of methanol solution, stir evenly, then add 8 g of maleic anhydride, heat to 75 °C while stirring, then add 0.7 g of azobisisobutyronitrile, continue to react for 50 min, and then vacuum dry at 80 °C for 24 min to obtain modified tetrahydrofurfuryl acrylate; S2. Disperse 12 g of nano-silica in a mixed solution of 330 g of deionized water and 50 g of absolute ethanol, then add 12 g of silane coupling agent (7 g of KH550 and 5 g of KH570), stir and react at 65 °C for 5 h, filter, wash and dry to obtain modified nano-silica; S3. Mix 9 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide TP0 with 6 g of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone to obtain a photoinitiator; then mix 9 g of 1,6-hexanediol diacrylate, 17 g of modified tetrahydrofurfuryl acrylate, and 4 g of trimethylolpropane trimethacrylate to obtain a reactive monomer; S4. Mix 15 g of cesium tungsten oxide, 4 g of C.I. Pigment White, 3.8 g of BYK 333, 3 g of BYK-3760 with a mass fraction of 0.5% and 68 g of reactive monomer evenly, grind to make the particle size of the infrared absorption pigment ≤ 50 nm, and filter precisely with a filter element with a fineness ≤ 0.22 μm to obtain anti-counterfeiting color paste; S5. Mix 28 g of anti-counterfeiting color paste, 4.2 g of photoinitiator, 1.3 g of modified nano-silica, 1.4 g of hydroxyphenylbenzotriazole and 40 g of isopropanol evenly, grind for 17 min at a rotation speed of 1400 r / min, and the pore size is 0.7 μm during filtration to obtain near-infrared absorption invisible UV inkjet ink.

[0044] Example 3: A preparation method of near-infrared absorption invisible UV inkjet ink, comprising the following steps: S1. Add 7 g of tetrahydrofurfuryl acrylate to 26 mL of methanol solution, stir evenly, then add 9 g of maleic anhydride, heat to 80 °C while stirring, then add 0.8 g of azobisisobutyronitrile, continue to react for 60 min, and then vacuum dry at 82 °C for 28 min to obtain modified tetrahydrofurfuryl acrylate; S2. Disperse 13 g of nano-silica in a mixed solution of 360 g of deionized water and 52 g of absolute ethanol, then add 15 g of silane coupling agent (10 g of KH550 and 5 g of KH570), stir and react at 65 °C for 6 h, filter, wash, and dry to obtain modified nano-silica; S3. Mix 11 g of 2,4-diethylthioxanthone with 7 g of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone to obtain a photoinitiator; then mix 11 g of dipropylene glycol diacrylate, 20 g of modified tetrahydrofurfuryl acrylate, and 5 g of trimethylolpropane trimethacrylate to obtain reactive monomers; S4. Mix 16 g of lanthanum hexaboride, 4.5 g of C.I. Pigment White, 3.8 g of BYK 333, 3 g of BYK-3760 with a mass fraction of 0.5%, and 72 g of reactive monomers evenly, grind to make the particle size of the infrared absorbing pigment ≤ 50 nm, and finely filter using a filter element with a fineness ≤ 0.22 μm to obtain an anti-counterfeiting color paste; S5. Mix 30 g of anti-counterfeiting color paste, 4.6 g of photoinitiator, 1.4 g of modified nano-silica, 1.5 g of benzophenone, and 40 g of ethyl acetate evenly, grind at a rotation speed of 1600 r / min for 18 min, and the pore size during filtration is 0.8 μm to obtain a near-infrared absorbing invisible UV inkjet ink.

[0045] Example 4: A preparation method of a near-infrared absorbing invisible UV inkjet ink, comprising the following steps: S1. Add 8 g of tetrahydrofurfuryl acrylate to 28 mL of methanol solution, stir evenly, then add 10 g of maleic anhydride, heat to 85 °C while stirring, then add 1 g of azobisisobutyronitrile, continue to react for 65 min, and vacuum dry at 85 °C for 30 min to obtain modified tetrahydrofurfuryl acrylate; S2. Disperse 15 g of nano-silica in a mixed solution of 380 g of deionized water and 45 g of absolute ethanol, then add 20 g of silane coupling agent (7 g of KH550 and 13 g of KH570), stir and react at 70 °C for 6 h, filter, wash, and dry to obtain modified nano-silica; S3. Mix 13 g of 2,4-diethylthioxanthone with 8 g of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone to obtain a photoinitiator; then mix 13 g of dipropylene glycol diacrylate, 22 g of modified tetrahydrofurfuryl acrylate, and 6 g of trimethylolpropane trimethacrylate to obtain reactive monomers; S4. Mix 18 g of lanthanum hexaboride, 5 g of C.I. Pigment White, 4 g of BYK 333, 3.5 g of BYK-3760 with a mass fraction of 0.5%, and 75 g of reactive monomer uniformly, grind them to make the particle size of the infrared absorption pigment ≤ 50 nm, and filter them precisely with a filter element with a fineness ≤ 0.22 μm to obtain an anti-counterfeiting color paste; S5. Mix 32 g of anti-counterfeiting color paste, 5.5 g of photoinitiator, 1.6 g of modified nano-silica, 2 g of salicylate, and 45 g of butyl acetate uniformly, grind them at a rotation speed of 1800 r / min for 20 min, and the pore size during filtration is 1 μm to obtain a near-infrared absorption invisible UV inkjet ink.

[0046] Comparative Example 1: Compared with Example 1, KH550 was not added during the preparation process of nano-silica in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorption invisible UV inkjet ink was obtained.

[0047] Comparative Example 2: Compared with Example 1, KH570 was not added during the preparation process of nano-silica in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorption invisible UV inkjet ink was obtained.

[0048] Comparative Example 3: Compared with Example 1, only "photoinitiator A" was replaced with "photoinitiator B" in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorption invisible UV inkjet ink was obtained.

[0049] Comparative Example 4: Compared with Example 1, only "photoinitiator B" was replaced with "photoinitiator A" in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorption invisible UV inkjet ink was obtained.

[0050] Comparative Example 5: Compared with Example 1, trimethylolpropane trimethacrylate was not added in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorption invisible UV inkjet ink was obtained.

[0051] Comparative Example 6: Compared with Example 1, only "1,6-hexanediol diacrylate" was replaced with "modified tetrahydrofurfuryl acrylate" in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorption invisible UV inkjet ink was obtained.

[0052] Comparative Example 7: In this comparative example, compared with Example 1, only "modified tetrahydrofurfuryl acrylate" was replaced with "tetrahydrofurfuryl acrylate", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorbing invisible UV inkjet ink was obtained.

[0053] Comparative Example 8: In this comparative example, compared with Example 1, only "7 g of 1,6-hexanediol diacrylate and 15 g of modified tetrahydrofurfuryl acrylate" was replaced with "15 g of 1,6-hexanediol diacrylate and 7 g of modified tetrahydrofurfuryl acrylate", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a near-infrared absorbing invisible UV inkjet ink was obtained.

[0054] Performance test: Curing time: Take an appropriate amount of the near-infrared absorbing invisible UV inkjet inks prepared in Examples 1-4 and Comparative Examples 1-8, evenly coat them on copperplate paper, and cure them into a film through an ultraviolet curing machine. Use the finger-drying method to judge the curing degree of the ink, and record the photocuring time; Hardness: According to GB / T 6739-2022 "Pencil method for determining film hardness", determine the hardness of the cured films prepared in Examples 1-4 and Comparative Examples 1-8; Use a set of Zhonghua brand high-grade drawing pencils from 9B to 9H, push the pencils with gradually increasing hardness on the horizontal cured film, and the pushing speed is 0.5 mm / s - 1 mm / s. If no scratches appear, replace the pencil with a higher hardness until scratches exceeding 3 mm appear. If scratches exceeding 3 mm in length have already appeared, replace the pencil with a lower hardness until no scratches exceeding 3 mm in length appear again; the film hardness is the hardness of the hardest pencil that does not cause 3 mm scratches on the film; Test environment: temperature is (23 ± 2) °C, humidity is (50 ± 5)%; Abrasion resistance: Use an MCJ-01A type friction testing machine to rub the cured films of the near-infrared absorbing invisible UV inkjet inks prepared in Examples 1-4 and Comparative Examples 1-8 back and forth 50 times with standard copperplate paper, wipe off the abraded floating debris, weigh, and the mass difference before and after grinding is the film weight loss; Specimen size: 230 mm × 50 mm; Friction pressure: 20 N; Friction speed: 3 cpm; Test environment: temperature is (23 ± 2) °C, humidity is (50 ± 5)%; Adhesion: The adhesion of the ink layer was tested in accordance with the national standard GB / T 9286-2021; test environment: temperature (23±2)°C, humidity (50±5)%.

[0055] Table 1 ; Data analysis: As can be seen from Table 1, the near-infrared absorbing invisible UV inkjet ink prepared by the present invention has a faster curing rate and higher wear resistance. Comparing the data of Example 1 with those of Comparative Examples 1 and 2, it can be seen that the simultaneous use of KH550 and KH570 can improve the wear resistance, hardness and adhesion of the near-infrared absorbing invisible UV inkjet ink. Comparing the data of Example 1 with those of Comparative Examples 3 and 4, it can be seen that the simultaneous use of photoinitiator A and photoinitiator B can improve the curing rate. Comparing the data of Example 1 with those of Comparative Examples 5 and 6, it can be seen that through the synergistic effect of 1,6-hexanediol diacrylate, modified tetrahydrofurfuryl acrylate and trimethylolpropane trimethacrylate, the adhesion, hardness and wear resistance of the near-infrared absorbing invisible UV inkjet ink can be significantly improved. Comparing the data of Example 1 with those of Comparative Example 7, it can be seen that the modification of tetrahydrofurfuryl acrylate with maleic anhydride can improve the adhesion, hardness and wear resistance of the near-infrared absorbing invisible UV inkjet ink.

[0056] Those of ordinary skill in the art should understand that: the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

[0057] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A near-infrared absorbing invisible UV inkjet ink, characterized in that: Including the following raw materials by weight: Anti-counterfeiting color paste 25-32 parts, photoinitiator 3.7-5.5 parts, auxiliary agent 1.1-1.6 parts, stabilizer 1-2 parts; The anti-counterfeiting color paste is prepared from infrared absorbing pigment, CI pigment white, leveling agent, surfactant and active monomer in a mass ratio of 12-18:3-5:3.2-4:2-3.5:63-75; The active monomer is obtained by mixing active monomer A, active monomer B and active monomer C in a mass ratio of 15-22:7-13:3-6; The active monomer A is modified tetrahydrofurfuryl acrylate; The active monomer B is at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and triethylene glycol diacrylate; The active monomer C is trimethylolpropane trimethacrylate; The modified tetrahydrofurfuryl acrylate is prepared by reacting maleic anhydride and tetrahydrofurfuryl acrylate; The photoinitiator is obtained by mixing photoinitiator A and photoinitiator B in a mass ratio of 7-13:5-8; The photoinitiator A is any one of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide TPO and 2,4-diethylthioxanthone; The photoinitiator B is 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone; The auxiliary agent is modified nano silicon dioxide; The modified nano silicon dioxide is prepared by reacting nano silicon dioxide with a silane coupling agent.

2. The near infrared absorbing invisible UV inkjet ink according to claim 1, characterized in that: The preparation method of the modified tetrahydrofurfuryl acrylate is as follows: Tetrahydrofurfuryl acrylate is added to the methanol solution, stirred evenly, and then maleic anhydride is added, and the mixture is heated to 70-85°C while stirring, and then azobisisobutyronitrile is added. After continuing the reaction for 45-65 minutes, vacuum drying is performed to obtain modified tetrahydrofurfuryl acrylate.

3. The near infrared absorbing invisible UV inkjet ink according to claim 2, characterized in that: The usage ratio of methanol, tetrahydrofurfuryl acrylate, maleic anhydride and azobisisobutyronitrile is 20-28mL: 5-8g: 7-10g: 0.5-1g; The vacuum drying is carried out at a temperature of 78-85°C and for a time of 20-30 minutes.

4. The near infrared absorbing invisible UV inkjet ink according to claim 1, characterized in that: The preparation method of the modified nano silicon dioxide is as follows: The nano-silicon dioxide is dispersed in a mixed solution of deionized water and anhydrous ethanol, and then a silane coupling agent is added, and the mixture is stirred and reacted at 60-70° C. for 4-6 hours, filtered, washed, and dried to obtain the modified nano-silicon dioxide.

5. The near infrared absorption invisible UV inkjet ink according to claim 4, characterized in that: The mass ratio of the nano-silica, deionized water, anhydrous ethanol and alkane coupling agent is (11-15): (300-380): (45-58): (10-20); the silane coupling agent is a mixture of an aminosilane coupling agent and a vinylsilane coupling agent.

6. The near infrared absorbing invisible UV inkjet ink according to claim 1, characterized in that: The preparation method of the anti-counterfeiting color paste is as follows: The infrared absorbing pigment, CI pigment white, leveling agent, surfactant and active monomer are uniformly mixed, ground to make the particle size of the infrared absorbing pigment ≤50nm, and finely filtered using a filter element with a fineness of ≤0.22μm to obtain an anti-counterfeiting color paste; The surfactant is BYK-3760 with a mass fraction of 0.5%; The stabilizer is at least one of hydroxyphenyl triazine, hydroxyphenyl benzotriazole, benzophenone, N,N'-oxalyl dianilide, cyanoacrylate and salicylate.

7. The near infrared absorbing invisible UV inkjet ink according to claim 1, characterized in that: The infrared absorbing pigment is at least one of composite tungsten oxide and lanthanum hexaboride.

8. A method for preparing the near-infrared absorbing invisible UV inkjet ink according to any one of claims 1 to 7, characterized in that: The following steps are involved: The anti-counterfeiting color paste, photoinitiator, additive, stabilizer and solvent are uniformly mixed, ground and filtered to obtain near-infrared absorbing invisible UV inkjet ink.

9. The method for preparing near infrared absorbing invisible UV inkjet ink according to claim 8, characterized in that: The rotation speed during grinding is 1200-1800 r / min, and the grinding time is 15-20 min.

10. The method for preparing the near-infrared absorbing invisible UV inkjet ink according to claim 8, characterized in that: The pore size during the filtration is 0.5-1 μm.