A UV-curable ink and its preparation method

Abstract

This invention discloses a UV-curable ink and its preparation method. The preparation steps of the UV-curable ink are as follows: An emulsifier is mixed with a polar organic solvent, then a non-polar organic solvent is added and heated and stirred until homogeneous. A dispersion of metal oxide particles is added to the resulting mixture, and after thorough stirring and reaction, a microemulsion containing metal oxide particles is obtained. A silicon source precursor is added to the obtained microemulsion, and the mixture is heated and reacted to obtain silica-coated metal oxide particles. The obtained silica-coated metal oxide particles are added to a monomer to obtain a dispersion system. A prepolymer, photoinitiator, pigment, additives, defoamer, antibacterial agent, and filler are added to the dispersion system, and the mixture is stirred and pre-dispersed until no solid powder lumps remain in the system. The system is then fed into a sand mill for grinding and dispersion to obtain the UV-curable ink. The UV-curable ink provided by this invention not only has excellent mechanical properties but also features fast curing speed, excellent antibacterial properties, and good water and salt resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ink materials, and particularly relates to a UV-cured ink and a preparation method thereof. BACKGROUND

[0002] UV ink refers to an ink which is dried and formed into a film by polymerization of monomers in the ink binder into polymers under the irradiation of ultraviolet light. Compared with traditional ink, UV ink is completely different in curing mechanism and curing mode: specifically, UV ink must be cured after being irradiated by ultraviolet light, so the curing speed is very fast; while traditional ink is generally dried by penetration, volatilization or oxidation film formation, and usually needs to be cured by natural air drying or heating drying, so the curing speed is very fast (Cao Zhengmin, Wang Xiaomin, Jiao Liyong. UV ink composition and curing influence factors [J]. Mechanical and electrical information, 2005 (2): 19-20). In addition, traditional ink also contains 30%-70% of toxic organic solvents, which has adverse effects on the health of the operating personnel and the surrounding environment during printing, while UV ink replaces the solvents in traditional ink with dilution monomers participating in the photocuring reaction, so that the film layer is basically free of solvent volatilization and emission after curing, which fully meets the requirements of low-carbon environmental protection; therefore, it can be said that UV-cured ink is an energy-saving and environmentally friendly ink born under the call of low-carbon environmental protection policy.

[0003] At present, the application of UV ink has covered all printing fields, especially in high-grade printed matters such as food, tobacco, wine, cosmetics and electronic products, which are used more often, because the UV ink containing a luminescent agent can usually produce a unique visual effect after photocuring, which is elegant, dignified and luxurious. However, in the application of UV ink, low adhesion has been one of the important factors restricting its development (Jia, Xiaoxue; Huang, Beiqing; Wei, Xianfu; et al. Influence of monomer on the performance of UV waterless offset ink [J]. Advanced Materials Research, 2011, 174: 425-428). In addition, there are few UV inks with antibacterial properties on the market. Therefore, it is very promising to develop a UV ink with strong adhesion and antibacterial properties. SUMMARY

[0004] The purpose of the present application is to provide a UV-cured ink and a preparation method thereof.

[0005] In order to achieve the above purpose, the solution of the present application is:

[0006] A method for preparing a UV-curable ink, comprising the following steps:

[0007] (1) mixing an emulsifier with a polar organic solvent, then adding a non-polar organic solvent and stirring uniformly under heating, adding a metal oxide particle dispersion liquid into the obtained mixture, and preparing a microemulsion containing metal oxide particles after sufficient stirring and reaction; and preparing silica-coated metal oxide particles after further heating and reaction of the obtained microemulsion with a silicon source precursor;

[0008] (2) adding the silica-coated metal oxide particles prepared in step (1) into a monomer and stirring uniformly to prepare a dispersion system containing silica-coated metal oxide particles;

[0009] (3) adding a prepolymer, a photoinitiator, a pigment, an additive, an antifoaming agent, an antibacterial agent, and a filler into the dispersion system containing silica-coated metal oxide particles prepared in step (2) and stirring to pre-disperse the system without solid powder, and then feeding into a sand mill for grinding and dispersion to prepare the UV-curable ink.

[0010] Preferably, the emulsifier in step (1) is one of fatty alcohol polyoxyethylene ether, polyoxyethylene stearate, or cetylphenol polyoxyethylene ether.

[0011] Preferably, the metal oxide in step (1) is one or a combination of two or more of zinc oxide, cerium dioxide, titanium dioxide, magnesium oxide, or aluminum oxide.

[0012] Preferably, the silicon source precursor in step (1) is one of methyl orthosilicate, ethyl orthosilicate, or isopropyl orthosilicate.

[0013] Preferably, the monomer in step (2) is one of lauryl acrylate, tripropyleneglycol diacrylate, neopentyl glycol diacrylate, or trimethylolpropane triacrylate.

[0014] Preferably, the prepolymer in step (3) is one or a combination of two or more of epoxy acrylate, polyurethane acrylate, or polyester acrylate.

[0015] Preferably, the photoinitiator in step (3) is one of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl ethyl phenylphosphonate, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, or methyl benzoylformate.

[0016] Preferably, the grinding dispersion speed in step (3) is 1000-2000 r / min, and the grinding dispersion time is 0.5-2 h.

[0017] The UV curing ink prepared by the preparation method of the UV curing ink has a mass ratio of the silica-coated metal oxide particles of 1.0-2.5%, and a mass ratio of the antibacterial agent of 0.1%-1.0%.

[0018] The specific principle of the preparation method of the UV curing ink provided by the application is as follows:

[0019] The preparation method of the UV curing ink provided by the application first prepares a metal oxide particle-containing microemulsion by using a microemulsion method, and then prepares silica-coated metal oxide particles by using a multi-phase reaction with a silicon source precursor; a series of silica-coated metal oxide particles are obtained by coating different metal oxide particles, and a series of UV curing inks with different properties are prepared; the application particularly and in detail investigates the influence of different silica-coated metal oxide particles on the performance of the UV curing ink, especially the influence on the curing speed and adhesion. Specifically, the silica-coated metal oxide particles have strong ultraviolet light absorption capacity, and the addition of the silica-coated metal oxide particles to the UV curing ink can effectively promote the absorption of ultraviolet light by the ink, and thus improve the drying speed of the ink; different silica-coated metal oxide particles have different ultraviolet light absorption capacity. In addition, the silver-cuprous oxide-loaded carboxylated chitosan composite powder with antibacterial performance is added to the UV curing ink, so that the antibacterial agent can continuously exert the antibacterial performance in the prepared ink, which not only enables the ink to have excellent antibacterial performance, but also further improves the mechanical properties of the prepared ink.

[0020] Compared with the existing UV curing ink and the preparation method thereof, the gain effect of the application is as follows:

[0021] 1.The method for preparing UV-curable ink provided by the present application can effectively improve the curing speed and adhesion of the prepared ink by using silica-coated metal oxide particles, and the adhesion, water resistance and salt resistance of the obtained ink can be further improved by compounding pre-polymer polyester acrylate and polyurethane acrylate.

[0022] 2.The method for preparing UV-curable ink provided by the present application can make the prepared ink have long-lasting and excellent antibacterial performance by using silver-cuprous oxide loaded carboxymethyl chitosan composite powder.

[0023] 3.The method for preparing UV-curable ink provided by the present application does not use any toxic volatile organic solvents throughout the process, and has the advantages of green environmental protection. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in combination with examples. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as a limitation on the protection scope of the present application. The specific mass, reaction time and temperature, process parameters and the like in the examples are only one example in the appropriate range, and some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application all belong to the protection scope of the present application.

[0025] The reagents used are all commercial reagents, and no further purification is performed before use.

[0026] The pigments used in the examples of the present application are all commercial reagents, and the pigments and fillers can be adjusted according to the specific color needs, for example, phthalocyanine blue pigment can be used for blue color, carbon black pigment can be used for black color, and carbon dioxide powder can be used for white color.

[0027] The preparation method of the silver-cuprous oxide loaded carboxylated chitosan composite powder used in the embodiment of the application is as follows: 15 g of chitosan is dissolved in 1.25 L of 9% acetic acid solution, and after stirring for 2.5 h, a mixture powder composed of 15 g of coconut shell carbon and 15 g of diatomite is added, and stirring is continued for 2 h. After filtration, the obtained solid is washed with deionized water until the pH value of the collected eluate is close to 7. The washed solid is dried at 110 ℃ to prepare a carboxylated chitosan composite carrier. The carboxylated chitosan composite carrier prepared in the step is added to 200 ml of 5% acetic acid solution, and then 80 ml of 50 mmol / L copper nitrate solution is slowly added dropwise and stirred uniformly. After continuous stirring, 20 ml of 10% ascorbic acid solution is added, and the pH value is adjusted to 6.5 with dilute ammonia water. After that, the obtained mixture is hydrothermally reacted at 200 ℃ for 2 h. After cooling, the solution is centrifuged, washed with 250 ml of deionized water for 3 times, and washed with 250 ml of anhydrous ethanol for 3 times. After freeze-drying, the obtained solid is collected to prepare a cuprous oxide loaded carboxylated chitosan composite material. The prepared cuprous oxide loaded carboxylated chitosan composite material, 15 ml of 10% ascorbic acid solution, 0.6 g of sodium citrate and 1.1 g of polyvinylpyrrolidone (average relative molecular mass is 40000) are added to 500 ml of deionized water and stirred uniformly. Then, 40 ml of 50 mmol / L silver nitrate solution is slowly added dropwise. The obtained mixture is placed in a microwave reactor and subjected to microwave reaction at 100 ℃ for 45 min. After filtration, a silver-cuprous oxide loaded carboxylated chitosan composite powder is prepared.

[0028] Example 1:

[0029] The preparation steps of the UV-cured ink are as follows:

[0030] (1) 18 g of emulsifier polyoxyethylene stearate is mixed with 16 g of n-hexanol, and then 13 g of cyclohexane is added and heated to 32 ℃ and stirred uniformly. 10 mL of ZnO dispersion liquid (ZnO dispersion liquid is prepared by adding 1.0 g of ZnO into 10 mL of deionized water and ultrasonic dispersion for 5 min) is added into the obtained mixture, and stirring is continued at 32 ℃ and the reaction temperature is accurately controlled. After stirring for 2 h, ZnO microemulsion is prepared. Then, 0.3 g of tetraethyl orthosilicate is added and stirred uniformly. After that, the obtained mixture is moved into an ultrasonic reactor and subjected to ultrasonic oscillation reaction at 30 ℃ for 35 min. After centrifugal separation, the obtained solid is washed with 50 ml of 60% ethanol aqueous solution for 3 times. After that, the obtained solid is placed in a vacuum drying box and dried at 65 ℃ for 5 h, and then placed in a muffle furnace and calcined at 400 ℃ for 3 h to prepare silica coated zinc oxide particles;

[0031] (2) 1 g of the silica-coated zinc oxide particles prepared in step (1) was added to 45 g of neopentyl glycol diacrylate and stirred to prepare a dispersion containing the silica-coated zinc oxide particles;

[0032] (3) To the dispersion containing the silica-coated zinc oxide particles prepared in step (2) were added 40 g of epoxy acrylate, 2 g of 2-hydroxy-2-methyl-1-phenylpropanone, 10 g of carbon black, 0.5 g of silicone oil, 0.5 g of CI-2212 defoaming agent, 0.1 g of silver-copper oxide supported carboxylated chitosan composite powder, and 0.9 g of calcium carbonate, and stirred to pre-disperse the solids in the system, and then fed into a sand mill for grinding and dispersion. The rotation speed of the sand mill was set to 1400 r / min, and the time was 30 min. Finally, the product was filtered through a 300 mesh screen to prepare the UV-curable ink. The obtained UV-curable ink was denoted as NPGDA-EA-ZnO@SiO2-1.

[0033] The curing time of the prepared UV-curable ink was tested as follows:

[0034] Treatment of the printing substrate: A tinplate sheet was cut into a test plate with a size of 50 mm x 120 mm x 0.3 mm, and the surface was wiped clean with alcohol and then dried under an infrared lamp. The prepared UV-curable ink was printed onto the freshly treated tinplate sheet using an IGT printing suitability instrument, and the amount of ink used each time was 0.1 ml.

[0035] Curing of the ink: The tinplate sheet printed with the ink was placed in a UV lamp curing box, and the 2 KW strong light button was twisted to expose the light, and the stopwatch was pressed to start timing. The time required for complete curing was taken as the curing time. The complete curing was indicated by the fingernail picking method, i.e. the cured film layer was lightly picked with a fingernail, and no ink dropping and no scratch indicated complete curing. The test results are shown in Table 1.

[0036] The prepared UV-curable ink 1NPGDA-EA-ZnO@SiO2-1 was made into a coating and then performance testing was carried out; wherein, the preparation of the NPGDA-EA-ZnO@SiO2-1 coating was prepared according to the method provided in GB / T1727-1992, and the specific steps were as follows: the tinplate piece meeting the specification of GB / T2520-2017 was cut into a test plate with a size of 50mm×120mm×0.3mm, and the test plate was cleaned according to the provisions of the test plate in GB9271-1988. After uniformly scraping the NPGDA-EA-ZnO@SiO2-1 material on the tinplate test plate with a scraper, the performance of each item was tested after complete curing under ultraviolet lamp irradiation. The properties of the coating film such as hardness, adhesion, water resistance and salt spray corrosion resistance were determined according to the corresponding national standards, and the details were as follows: the hardness was determined according to the national standard GB / T1730-93, the adhesion was determined according to the national standard GB / T1720-79, the resistance to distilled water (40℃ immersion) / h was determined according to the national standard GB / T5209-85, and the resistance to 3% NaCl (40℃) / h was determined according to the national standard GB / T1763-79. The results are shown in Table 1.

[0037] The antibacterial performance of the prepared UV-curable ink coating was detected by the film pasting method according to the execution standard QB / T 2591-2003 (QB / T 2591-2003, Test method for antibacterial performance of antibacterial plastics and antibacterial effect [S]. Beijing: State Development and Reform Commission of the People's Republic of China, 2003.) to investigate the inhibition rate of antibacterial plastics after contacting with test bacteria for 24 hours. The determination of total bacterial count was carried out according to GB / T 4789.2-2016 (GB / T 4789.2-2016, Food microbiology test-determination of total bacterial count [S]. Beijing: State Health and Family Planning Commission of the People's Republic of China, State Food and Drug Administration, 2016.), and the antibacterial rate was calculated according to the following formula:

[0038] R% = (B-A) / B x 100%

[0039] In the formula: R: antibacterial rate, %; A: average number of recovered bacteria of Ag / NH2-MgO / SiO2-EP coating sample after 24 hours of culture; B: average number of recovered bacteria of blank control sample after 24 hours of culture, and the blank control sample was a coating made of pure EP and curing agent polyamide resin (mass ratio of 1:1) according to the same method; the results are shown in Table 1.

[0040] Example 2:

[0041] The UV-curable ink was prepared according to Example 1, except that the metal oxide ZnO used in step (1) was replaced by CeO2, and the amount of CeO2 was 1 g; the other steps were the same as Example 1, and the obtained UV-curable ink was recorded as NPGDA-EA-CeO2@SiO2-2.

[0042] The preparation and performance characterization of NPGDA-EA-CeO2@SiO2-2 coating were the same as Example 1; the results are shown in Table 1.

[0043] Example 3:

[0044] The UV-curable ink was prepared according to Example 1, except that the metal oxide ZnO used in step (1) was replaced by TiO2, and the amount of TiO2 was 1 g; the other steps were the same as Example 1, and the obtained UV-curable ink was recorded as NPGDA-EA-TiO2@SiO2-3.

[0045] The preparation and performance characterization of NPGDA-EA-TiO2@SiO2-3 coating were the same as Example 1; the results are shown in Table 1.

[0046] Example 4:

[0047] The UV-curable ink was prepared according to Example 1, except that the metal oxide ZnO used in step (1) was replaced by MgO, and the amount of MgO was 1 g; the other steps were the same as Example 1, and the obtained UV-curable ink was recorded as NPGDA-EA-MgO@SiO2-4.

[0048] The preparation and performance characterization of NPGDA-EA-MgO@SiO2-4 coating were the same as Example 1; the results are shown in Table 1.

[0049] Example 5:

[0050] The UV-curable ink was prepared according to Example 1, except that the metal oxide ZnO used in step (1) was replaced by Al2O3, and the amount of Al2O3 was 1 g; the other steps were the same as Example 1, and the obtained UV-curable ink was recorded as NPGDA-EA-Al2O3@SiO2-5.

[0051] The preparation and performance characterization of NPGDA-EA-Al2O3@SiO2-5 coating were the same as Example 1; the results are shown in Table 1.

[0052] Example 6:

[0053] The UV-curable ink was prepared according to Example 1 except that the metal oxide ZnO used in step (1) was replaced by a mixed powder composed of Ti02 and MgO, the amount of Ti02 was 0.5 g, and the amount of MgO was 0.5 g; the other steps were the same as in Example 1, and the obtained UV-curable ink was denoted as NPGDA-EA-MgO-Ti02@Si02-6.

[0054] The preparation and performance characterization of the NPGDA-EA-MgO-Ti02@Si02-6 coating were the same as in Example 1; the results are shown in Table 1.

[0055] Table 1 Influence of different oxides on the performance of UV-curable ink

[0056] Example Curing time Hardness Adhesion Water resistance Salt resistance Antibacterial rate A Antibacterial rate B 1 9s 0.85 2nd grade 144h 144h 89.2％ 93.0％ 2 6s 0.84 2nd grade 144h 144h 82.3％ 87.1％ 3 4s 0.88 1st grade 144h 144h 87.9％ 90.2％ 4 6s 0.92 1st grade 144h 144h 88.5％ 90.8％ 5 13s 0.93 2nd grade 144h 144h 83.7％ 88.4％ 6 4s 0.91 1st grade 144h 144h 89.1％ 91.0％

[0057] Examples 7-9:

[0058] The UV-curable ink was prepared according to Example 1 except that the metal oxide ZnO used in step (1) was replaced by a mixed powder composed of Ti02 and MgO, the amount of Ti02 was 0.5 g, and the amount of MgO was 0.5 g; the neopentyl glycol diacrylate in step (2) was replaced by lauryl acrylate, tripropyleneglycol diacrylate, and trimethylolpropane triacrylate, respectively; the other steps were the same as in Example 1, and the preparation and performance characterization of the obtained ink coating were the same as in Example 1; the results are shown in Table 2.

[0059] Table 2 Influence of different monomers or prepolymers on the performance of UV-curable ink

[0060]

[0061]

[0062] Note: The water resistance and salt resistance both refer to the time without change; the antibacterial rate A refers to the antibacterial rate against Escherichia coli, and the antibacterial rate B refers to the antibacterial rate against Staphylococcus aureus.

[0063] Examples 10-12:

[0064] The UV-curable ink was prepared according to Example 1 except that the metal oxide ZnO used in step (1) was replaced by a mixed powder composed of Ti02 and MgO, the amount of Ti02 was 0.5 g, and the amount of MgO was 0.5 g; the neopentyl glycol diacrylate in step (2) was replaced by trimethylolpropane triacrylate; the epoxy acrylate in step (3) was replaced by polyurethane acrylate and polyester acrylate, respectively; the other steps were the same as in Example 1, and the preparation and performance characterization of the obtained ink coating were the same as in Example 1; the results are shown in Table 2.

[0065] Example 13:

[0066] The preparation of UV-curable ink was carried out in accordance with Example 1, except that the metal oxide ZnO used in step (1) was replaced with a mixed powder composed of TiO2 and MgO, with 0.5g of TiO2 and 0.5g of MgO; neopentyl glycol diacrylate in step (2) was replaced with trimethylolpropane triacrylate; and epoxy acrylate in step (3) was replaced with a composite prepolymer composed of epoxy acrylate, polyurethane acrylate and polyester acrylate in a mass ratio of 1:1:2. The remaining steps were the same as in Example 1, and the preparation and performance characterization of the resulting ink coating were the same as in Example 1. The results are shown in Table 2.

[0067] Example 14:

[0068] The UV-curable ink was prepared according to Example 1, except that the ZnO metal oxide used in step (1) was replaced with a mixed powder composed of TiO2 and MgO, with 0.5g of TiO2 and 0.5g of MgO; the neopentyl glycol diacrylate in step (2) was replaced with trimethylolpropane triacrylate; the epoxy acrylate in step (3) was replaced with a composite prepolymer composed of epoxy acrylate, polyurethane acrylate and polyester acrylate in a mass ratio of 1:1:2; and the amount of silver-cuprous oxide-supported carboxylated chitosan composite powder in step (3) was changed to 0g; the remaining steps were the same as in Example 1, and the preparation and performance characterization of the resulting ink coating were the same as in Example 1; the results are shown in Table 2.

Claims

1. A method for preparing a UV-curable ink, characterized in that, The method comprises the following steps: (1) mixing an emulsifier with a polar organic solvent, then adding a non-polar organic solvent and stirring uniformly under heating, adding a metal oxide particle dispersion into the obtained mixture, and preparing a microemulsion containing metal oxide particles after fully stirring and reacting; adding a silicon source precursor into the obtained microemulsion and continuing to react under heating to prepare silica-coated metal oxide particles; wherein the metal oxide is a mixed powder composed of TiO2 and MgO, the amount of TiO2 is 0.5 g, and the amount of MgO is 0.5 g; the polar organic solvent is n-hexanol, and the non-polar organic solvent is cyclohexane; (2) adding the silica-coated metal oxide particles prepared in step (1) into a monomer and stirring uniformly to prepare a dispersion containing silica-coated metal oxide particles; the monomer is trimethylolpropane triacrylate; (3) adding a prepolymer, a photoinitiator, a pigment, an additive, an antifoaming agent, an antibacterial agent, and a filler into the dispersion containing silica-coated metal oxide particles prepared in step (2) and stirring to pre-disperse the solid particles in the system, then feeding into a sand mill for grinding and dispersing to prepare the UV-curable ink; wherein the antibacterial agent is a silver-cuprous oxide loaded carboxylated chitosan composite powder; the prepolymer is composed of epoxy acrylate, polyurethane acrylate, and polyester acrylate at a mass ratio of 1:1:

2.

2. The method for preparing UV-curable ink according to claim 1, characterized in that, The emulsifier in step (1) is one of fatty alcohol polyoxyethylene ether, polyoxyethylene stearate, or cetylphenol polyoxyethylene ether.

3. The method for preparing UV-curable ink according to claim 1, characterized in that, The silicon source precursor in step (1) is one of tetramethyl orthosilicate, tetraethyl orthosilicate, or tetraisopropyl orthosilicate.

4. The method for preparing UV-curable ink according to claim 1, characterized in that, The photoinitiator in step (3) is one of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, 2,4,6-trimethylbenzoyl phenyl phosphonate ethyl ester, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, or methyl benzoylformate.

5. The method for preparing UV-curable ink according to claim 1, characterized in that, The grinding and dispersing speed in step (3) is 1000-2000 r / min, and the grinding and dispersing time is 0.5-2 h.

6. A UV-curable ink prepared by the method of any one of claims 1 to 5, characterized in that, The mass percentage of the silica-coated metal oxide particles is 1.0-2.5%, and the mass percentage of the antibacterial agent is 0.1%-1.0%.

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