A low migration UV light curing digital printing label inkjet ink and preparation method thereof

Abstract

The present invention provides a low migration UV light-curing digital printing label inkjet ink and a preparation method thereof, comprising the following components by mass: 3-5 parts of epoxy acrylate oligomer, 5-10 parts of polyurethane acrylate oligomer, 4-6 parts of trimethylolpropane triacrylate, 60-70 parts of 1,6-hexanediol diacrylate, 6-10 parts of isopropyl acrylamide, 10-18 parts of UV submicron color paste, 1-2 parts of modified silica, and 1-2 parts of polymerizable photoinitiator; wherein the modified silica is a product obtained by partially grafting organic acid with hydroxylated silica; the UV submicron color paste comprises a pigment, 1,6-hexanediol diacrylate and a dispersant. In the low migration UV light-curing digital printing label inkjet ink provided by the present invention, the compounding of multiple components effectively improves multiple properties of the ink, reduces the mobility of the ink, and overcomes the shortcomings and defects of the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of inkjet printing, and in particular to a low migration UV light curing digital printing label inkjet ink and a preparation method thereof. Background Art

[0002] UV curing ink is a special ink that can be hardened and attached by ultraviolet (UV) irradiation. Compared with traditional inks, this type of ink has many advantages such as fast curing speed, wide application in various industries, no volatility, and green environmental protection. Therefore, UV curing ink has been applied to many fields. For example, UV curing ink can be matched with various types of UV flatbed inkjet printers to achieve high-precision inkjet printing effects; UV curing ink can also be used to print labels, packaging and other materials to improve product recognition; in the advertising field, UV curing ink can also be used to make outdoor billboards, car body advertisements, etc.

[0003] However, in the actual application of photocurable ink, certain defects are also revealed: when printing product labels, UV curing ink has the problem of insufficient adhesion. After being placed under high temperature, high humidity or chemical corrosion conditions for a long time, the clarity of the label will be reduced; in the printing of food packaging, the ink on the label may also migrate, affecting food safety and causing harm to the human body, posing certain safety hazards.

[0004] In summary, existing UV light-curing inks can no longer meet the needs of the market and consumers, and there is an urgent need to develop a new technical solution to solve the problems existing in the existing technology. Summary of the invention

[0005] In the low migration UV light curing digital printing label inkjet ink provided by the present invention, epoxy acrylate oligomers, polyurethane acrylate oligomers and other components are compounded with modified silica, and the multiple components effectively improve multiple properties of the ink, reduce the mobility of the ink, and overcome the shortcomings and defects of the prior art.

[0006] One object of the present invention is to provide a low migration UV light curing digital printing label inkjet ink, wherein the low migration UV light curing digital printing label inkjet ink comprises the following components in parts by weight:

[0007]

[0008]

[0009] in,

[0010] The modified silicon dioxide is a product obtained by partially grafting an organic acid onto hydroxylated silicon dioxide;

[0011] The UV submicron color paste comprises a pigment, 1,6-hexanediol diacrylate and a dispersant.

[0012] Furthermore, the polymerizable photoinitiator is selected from polymerizable thioxanthone photoinitiators containing carbon-carbon double bonds.

[0013] Furthermore, the polymerizable photoinitiator is TXTBA.

[0014] Furthermore, the UV submicron color paste is selected from one or more of inorganic pigment white paste, colored organic pigment paste, and carbon black paste.

[0015] Furthermore, the pigment is selected from 122 pigment red, 15:4 phthalocyanine blue, 150 pigment yellow, Columbia 250 carbon black or DuPont 930 titanium dioxide.

[0016] Furthermore, the inorganic pigment white slurry comprises the following components in parts by weight: 50-70 parts of pigment (titanium dioxide), 25-45 parts of 1,6-hexanediol diacrylate, and 2-5 parts of dispersant;

[0017] The color organic pigment paste or carbon black paste comprises the following components in parts by weight: 10-25 parts of pigment, 65-88 parts of 1,6-hexanediol diacrylate, and 2-10 parts of dispersant.

[0018] Furthermore, the dispersant is selected from SD381 (Shanghai Yuansu Chemical Technology Co., Ltd.).

[0019] Furthermore, the silicon dioxide is nano silicon dioxide with an average particle size of 10-100 nm.

[0020] Furthermore, the organic acid is a mixture of a saturated acid and an unsaturated acid.

[0021] Another object of the present invention is to provide a method for preparing the above-mentioned low migration UV light curing digital printing label inkjet ink, comprising the following steps:

[0022] S1, hydroxylating silicon dioxide to obtain hydroxylated silicon dioxide;

[0023] S2, immersing the hydroxylated silicon dioxide in an organic acid, heating and ultrasonically reacting the mixture to obtain modified silicon dioxide;

[0024] S3, blending the modified silicon dioxide with other ingredients, and grinding to obtain the low migration UV light curing digital printing label inkjet ink.

[0025] Furthermore, in the organic acid, the mass ratio of saturated acid to unsaturated acid is 1:1-1:3.

[0026] Furthermore, the unsaturated acid is selected from oleic acid or linoleic acid.

[0027] Furthermore, in step S2, the temperature of the ultrasonic reaction is 60-90° C., and the time is 1-10 h.

[0028] The present invention has the following beneficial effects:

[0029] The invention provides a low migration UV light curing digital printing label inkjet ink, which consists of epoxy acrylate oligomer, polyurethane acrylate oligomer, acrylate monomer, modified silica and other components, wherein saturated acid and unsaturated acid are grafted on the surface of the modified silica, and the introduction of long chains improves the compatibility of the modified silica with organic polymers, and the modified silica can be more evenly dispersed in a mixed system, entangled with other organic chain segments, and play a reinforcing role. The long alkyl chain is also beneficial to improving the density of the ink and increasing the contact degree with the printing substrate, and the flexible chain segment can improve the mechanical properties, thereby improving the tear resistance and achieving the improvement of adhesion. At the same time, the double bond structure in the unsaturated acid enables the modified silica to be chemically cross-linked with components such as trimethylolpropane triacrylate and 1,6-hexanediol diacrylate having multiple functional groups, further improving the density of the network structure, and being beneficial to enhancing the stability of the ink, as well as the adhesion and strength. We also found that the ratio of saturated acid and unsaturated acid has a certain effect on the mobility of the product. As the amount of unsaturated acid (especially linoleic acid) increases, the mobility of the product decreases. This may be because the increase in unsaturated acid leads to a further increase in the degree of crosslinking, thereby improving the mobility.

[0030] In addition, the present invention also uses TXTBA as a photoinitiator. Compared with traditional initiators, this component has higher initiation efficiency. The double bonds it contains can participate in polymerization reactions, so it also has extremely low mobility. Compounding it with epoxy acrylate oligomers, polyurethane acrylate oligomers, acrylate monomers, modified silica and other components can further improve the adhesion effect, stability, and weather resistance of the ink product, and give the product low migration characteristics, which has good application prospects. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0032] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0033] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers indicating, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0034] The present invention uses the following raw materials:

[0035] Silicon dioxide, average particle size 50-100nm.

[0036] Epoxy acrylate oligomer, Sartomer CN153.

[0037] Polyurethane acrylate oligomer, Sartomer CU216NS.

[0038] The UV submicron white slurry is prepared by uniformly mixing titanium dioxide, 1,6-hexanediol diacrylate and SD381 in a mass ratio of 50:40:4, and grinding the mixture through a 1 μm filter membrane.

[0039] The UV submicron black slurry is prepared by uniformly mixing carbon black, 1,6-hexanediol diacrylate and SD381 in a mass ratio of 20:80:5 and grinding the mixture through a 1 μm filter membrane.

[0040] The UV submicron blue slurry is prepared by uniformly mixing phthalocyanine blue, 1,6-hexanediol diacrylate and SD381 in a mass ratio of 25:80:5 and grinding the mixture through a 1 μm filter membrane.

[0041] The polymerizable photoinitiator is TXTBA, and the preparation method of TXTBA comprises the following steps:

[0042] (1) Synthesis of 2-Hydroxythioxanthone

[0043] In an ice-water bath, add 12.24 g of 2,2-dithiosalicylic acid to a round-bottom flask, mix thoroughly with 40 ml of concentrated sulfuric acid, and then continue to add 25.56 g of phenol and 5.10 g of phosphorus pentoxide to the round-bottom flask. Remove the round-bottom flask from the ice-water bath, stir at room temperature for 1 hour, then heat to 70 ° C and react for 6 hours. After the reaction is completed, pour the mixed solution into ice water and filter. After washing the filter residue with water several times, wash the mixture with a 50 g / L sodium bicarbonate aqueous solution, adjust the pH to about 5-6, and after vacuum filtration, put it in an oven and dry it at 60 ° C. The crude product was recrystallized from a 1,4-dioxane solution to obtain 10.59 g of 2-hydroxythioxanthone as a yellow powder solid with a yield of 61%.

[0044] (2) Synthesis of tert-butyl 2-hydroxymethylacrylate

[0045] Dissolve 55.7 ml of tert-butyl acrylate in a mixed solution of 60 ml of tetrahydrofuran and 120 ml of water, and add 45.9 g of paraformaldehyde, 5.4 ml of triethylamine and 4.29 g of triethylenediamine. Stir the mixture at room temperature for 3.5 h, then heat it to 55 ° C and react for 21 h. After the reaction is completed, wait for the system to cool to room temperature and extract the mixture with ether. Add anhydrous sodium sulfate to the combined organic layer for drying. After filtering, take the filtrate and vacuum concentrate it with a rotary evaporator to obtain 36.2 g of colorless liquid tert-butyl 2-hydroxymethylacrylate with a yield of 60%.

[0046] (3) Synthesis of tert-butyl 2-bromomethylacrylate

[0047] Dissolve 4.6g of tert-butyl 2-hydroxymethylacrylate in 30ml of anhydrous ether, cool the solution to -30°C, and add 1.1ml of phosphorus tribromide. After the system is stable, heat it to 0°C and react for 3h. Then cool it to -10°C and add 2ml of water to stop the reaction. After warming to room temperature, extract the mixed solution to remove water, and purify the organic layer by silica gel chromatography. The eluent is petroleum ether: ethyl acetate = 15:1 (v / v). The product Rf value is about 0.7. 5.1g of colorless liquid tert-butyl 2-bromomethylacrylate is obtained.

[0048] (4) Synthesis of TXTBA

[0049] Under nitrogen, 0.72 g of 2-hydroxythioxanthone, 4.6 g of anhydrous potassium carbonate, and 10 ml of acetone were added to the sealed tube, and 0.8 g of tert-butyl 2-bromomethylacrylate was added dropwise at room temperature. After stirring at 60 ° C for 48 h, an appropriate amount of dichloromethane was added, and the excess potassium carbonate solid was filtered out. The filtrate was taken and purified by silica gel chromatography, and the eluent was petroleum ether: ethyl acetate = 10: 1 (v / v). The product Rf value was about 0.4. 0.62 g of yellow solid product TXTBA was obtained with a yield of 43%.

[0050] The "parts" in the embodiments of the present invention refer to parts by mass.

[0051] Example 1

[0052] A low migration UV light curing digital printing label inkjet ink, comprising the following components in parts by weight:

[0053]

[0054]

[0055] The method for preparing the low migration UV light curing digital printing label inkjet ink comprises the following steps:

[0056] S1, immersing silicon dioxide in a 33wt% hydrogen peroxide solution, reacting at 105°C for 6h, washing, and drying at 80°C for 2h to obtain hydroxylated silicon dioxide;

[0057] S2, mixing the hydroxylated silica, lauric acid and oleic acid in a mass ratio of 0.8:1:1, ultrasonically reacting at 80° C. for 10 h, filtering, washing and drying to obtain modified silica;

[0058] S3. According to the above mass fractions, the modified silicon dioxide is blended with other ingredients, and ground through a 1 μm filter membrane to obtain the low migration UV light-curable digital printing label inkjet ink.

[0059] Example 2

[0060] A low migration UV light curing digital printing label inkjet ink, comprising the following components in parts by weight:

[0061]

[0062] The method for preparing the low migration UV light curing digital printing label inkjet ink comprises the following steps:

[0063] S1, immersing silicon dioxide in a 33wt% hydrogen peroxide solution, reacting at 105°C for 6h, washing, and drying at 80°C for 2h to obtain hydroxylated silicon dioxide;

[0064] S2, mixing the hydroxylated silica, lauric acid and linoleic acid in a mass ratio of 0.8:0.8:1.5, ultrasonically reacting at 80° C. for 10 h, filtering, washing and drying to obtain modified silica;

[0065] S3. According to the above mass fractions, the modified silicon dioxide is blended with other ingredients, and ground through a 1 μm filter membrane to obtain the low migration UV light-curable digital printing label inkjet ink.

[0066] Example 3

[0067] A low migration UV light curing digital printing label inkjet ink, comprising the following components in parts by weight:

[0068]

[0069] The method for preparing the low migration UV light curing digital printing label inkjet ink comprises the following steps:

[0070] S1, immersing silicon dioxide in a 33wt% hydrogen peroxide solution, reacting at 105°C for 6h, washing, and drying at 80°C for 2h to obtain hydroxylated silicon dioxide;

[0071] S2, mixing the hydroxylated silica, lauric acid and linoleic acid in a mass ratio of 0.8:0.6:1.8, ultrasonically reacting at 80° C. for 10 h, filtering, washing and drying to obtain modified silica;

[0072] S3. According to the above mass fractions, the modified silicon dioxide is blended with other ingredients, and ground through a 1 μm filter membrane to obtain the low migration UV light-curable digital printing label inkjet ink.

[0073] Comparative Example 1

[0074] An inkjet ink. The difference between this comparative example and Example 1 is that the oleic acid in step S2 is replaced by lauric acid of equal mass, and the amounts of other components and the preparation method are the same as those in Example 1.

[0075] Comparative Example 2

[0076] An inkjet ink. The difference between this comparative example and Example 1 is that the polymerizable photoinitiator is replaced by an equal amount of ITX, and the amounts of other components and the preparation method are the same as those in Example 1.

[0077] Test Example 1

[0078] The ink prepared in the examples and comparative examples was photocured and printed on a BOPP plastic film with a surface energy of 38 dynes using a printer with an Epson S3200 nozzle. The rotational viscosity of the printing ink was 5-10 mPa·s at 30 rpm at a temperature of 45°C. The UV-LED lamp (20 W / cm 2 ) was photocured at 395 nm.

[0079] Mobility test:

[0080] Carry out migration test in accordance with the provisions of GB 34604.8-2021.

[0081] After the cured samples were placed at 50°C for 72 hours, the migration rate was retested.

[0082] The test results are shown in Table 1.

[0083] Table 1 Test results

[0084] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Clarity Clarity Clarity Clarity Clarity Clarity Mobility (%) 2.92 2.85 2.78 3.16 9.17 Migration rate after high temperature storage (%) 2.97 2.90 2.82 3.29 11.04

[0085] From the above data, it can be seen that the ink products of Examples 1-3 all have extremely low mobility, the photoinitiator can stably adhere to the surface of the product, and as the amount of unsaturated acid increases, the mobility also shows a downward trend, and after being placed at high temperature, the mobility of the embodiments remains at a low level without showing significant changes; while Comparative Example 1 replaces oleic acid with lauric acid, resulting in a decrease in the degree of crosslinking between molecules and an increase in mobility. Comparative Example 2 uses conventional ITX as a photoinitiator, and cannot obtain an ideal crosslinking structure, and the mobility increases significantly. After being placed at high temperature, the mobility changes significantly.

[0086] Test Example 2

[0087] Stability test:

[0088] According to the provisions of GB / T13217.7-2009, the adhesion strength of light-curing ink to PE and PP films was measured.

[0089] The cured samples were immersed in 5 wt % HCl and NaOH solutions for 24 h, respectively, and then taken out to detect whether there were obvious bubbles, cracks, or shedding to evaluate the acid and alkali resistance.

[0090] The test results are shown in Table 2.

[0091] Table 2 Stability test results

[0092] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Adhesion strength / %(PE) ＞90 ＞90 ＞90 ＞80 ＞80 Adhesion strength / %(PP) ＞90 ＞90 ＞90 ＞85 ＞80 Acid resistance good good good good good Alkali resistance good good good Poor good

[0093] According to Table 2, it can be seen that the ink prepared in the embodiment of the present invention has good stability, excellent adhesion fastness and acid and alkali resistance; Comparative Example 1 replaces unsaturated fatty acids, resulting in reduced crosslinking degree and stability, and Comparative Example 2 uses a conventional crosslinking agent, and the adhesion fastness is also reduced. In summary, the low migration UV light curing digital printing label inkjet ink of the present invention overcomes the shortcomings of the prior art and is of great significance to the development of UV curing inks.

[0094] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0095] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A low migration UV light curing digital printing label inkjet ink, characterized in that: The low migration UV light curing digital printing label inkjet ink comprises the following components in parts by weight: in, The modified silicon dioxide is a product obtained by partially grafting an organic acid onto hydroxylated silicon dioxide; The UV submicron color paste comprises a pigment, 1,6-hexanediol diacrylate and a dispersant.

2. The low migration UV light curing digital printing label inkjet ink according to claim 1, characterized in that: The polymerizable photoinitiator is selected from polymerizable thioxanthone photoinitiators containing carbon-carbon double bonds.

3. The low migration UV light curing digital printing label inkjet ink according to claim 1, characterized in that: The UV submicron color paste is selected from one or more of inorganic pigment white paste, colored organic pigment paste, and carbon black paste.

4. The low migration UV light curing digital printing label inkjet ink according to claim 1, characterized in that: The silicon dioxide is nano silicon dioxide with an average particle size of 10-100 nm.

5. The low migration UV light curing digital printing label inkjet ink according to claim 1, characterized in that: The dispersant is selected from SD381.

6. The low migration UV light curing digital printing label inkjet ink according to claim 1, characterized in that: The organic acid is a mixture of saturated acid and unsaturated acid.

7. The method for preparing the low migration UV light curing digital printing label inkjet ink according to any one of claims 1 to 6, characterized in that: The steps include: S1, hydroxylating silicon dioxide to obtain hydroxylated silicon dioxide; S2, immersing the hydroxylated silicon dioxide in an organic acid, heating and ultrasonically reacting the mixture to obtain modified silicon dioxide; S3, blending the modified silicon dioxide with other ingredients, and grinding to obtain the low migration UV light curing digital printing label inkjet ink.

8. The method for preparing the low migration UV light curing digital printing label inkjet ink according to claim 7, characterized in that: In the organic acid, the mass ratio of saturated acid to unsaturated acid is 1:1-1:

3.

9. The method for preparing the low migration UV light curing digital printing label inkjet ink according to claim 8, characterized in that: The unsaturated acid is selected from oleic acid or linoleic acid.

10. The method for preparing the low migration UV light curing digital printing label inkjet ink according to claim 7, characterized in that: In step S2, the temperature of the ultrasonic reaction is 60-90°C and the time is 1-10h.

Images