A high water-resistant printing ink and printing process thereof

Abstract

The present invention relates to the technical field of ink printing, specifically a highly water-resistant printing ink and a printing process thereof. The present invention mixes nano silicon dioxide, a photoinitiator, a toner, a polyurethane emulsion, water, a defoamer, a leveling agent, and a dispersant to obtain a highly water-resistant printing ink. In order to improve the water resistance of the ink, the present invention modifies the polyurethane emulsion, reacts methyl allyl alcohol with 1,1,3,3-tetramethyl disiloxane to obtain a silicon-containing diol, mixes the silicon-containing diol with a polyurethane prepolymer, and obtains a silicon-containing polyurethane prepolymer; then 1,4-butanediol and 3-allyloxy-1,2-propylene glycol are added to carry out a chain extension reaction to obtain a silicon-containing polyurethane having a double bond in the side chain; in addition, the present invention also uses 3-mercaptopropyl triethoxysilane to treat the surface of a polyethylene film, introduces a mercapto group, and can react with a carbon-carbon double bond in the polyurethane under the conditions of a photoinitiator and ultraviolet light irradiation, thereby improving the adhesion performance of the ink.

Description

Technical Field

[0001] The invention relates to the technical field of ink printing, in particular to a highly water-resistant printing ink and a printing process thereof. Background Art

[0002] Ink refers to a paste-like adhesive with color and a certain fluidity. It is composed of pigments (or colored bodies such as dyes), binders, fillers, additives and other substances. It can be used for printing and dried on the printed object. There are many types of inks. Among them, solvent-based polyurethane inks have good transparency, glossiness, flexibility, adhesion and weather resistance due to their special structure, which can make the ink have excellent printability.

[0003] However, as people's environmental awareness continues to strengthen, the volatile solvents in solvent-based polyurethane inks are harmful to the environment and do not meet environmental protection requirements and are gradually being eliminated. On the one hand, environmentally friendly water-based polyurethane inks contain more hydrophilic groups, which leads to a decrease in water resistance and solvent resistance. On the other hand, the surface tension of water is much greater than that of general volatile solvents, so it is difficult to adhere to plastic films, resulting in poor suitability when using water-based polyurethane inks for printing on plastic films, and poor printing effects. Therefore, it is very necessary to modify the existing technology and provide a new type of highly water-resistant printing ink. Summary of the invention

[0004] The object of the present invention is to provide a highly water-resistant printing ink and a printing process thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a highly water-resistant printing ink and a printing process thereof, comprising the following steps:

[0006] Step 1:

[0007] S11: adding methyl allyl alcohol to tetrahydrofuran, heating to 60-70°C, stirring for 5-10 minutes, adding isopropanol solution of chloroplatinic acid with a concentration of 0.02-0.03 g / mL, keeping the temperature, passing argon gas, adding 1,1,3,3-tetramethyldisiloxane dropwise, and reacting for 8-12 hours; removing the solvent tetrahydrofuran by vacuum distillation, and drying at a constant temperature to obtain a silicon-containing diol;

[0008] S12: vacuum dehydrating polyethylene glycol at 110-120° C. for 2-3 hours, heating the polyethylene glycol to 50-60° C., then adding isophorone diisocyanate and dibutyltin dilaurate while keeping the temperature, stirring for 30-60 minutes, heating to 70-80° C. and reacting for 2-3 hours to obtain a polyurethane prepolymer; adding silicon-containing diol to the polyurethane prepolymer while keeping the temperature, and continuing the reaction for 1-2 hours to obtain a silicon-containing polyurethane prepolymer;

[0009] S13: adding 1,4-butanediol, 3-allyloxy-1,2-propylene glycol and acetone to the silicon-containing polyurethane prepolymer at 40-50° C. to react for 1-2 hours, adding triethylamine to neutralize for 30 minutes, adding deionized water to emulsify for 10-15 minutes, and evaporating impurities to obtain a silicon-containing polyurethane emulsion;

[0010] S14: mixing nano silicon dioxide, a photoinitiator, a toner, a silicon-containing polyurethane emulsion, water, a defoamer, a leveling agent, and a dispersant uniformly, and allowing to stand for defoaming to obtain a highly water-resistant printing ink;

[0011] Step 2:

[0012] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0013] S22: immersing the pretreated polyethylene-based film in a mixed solution of 3-mercaptopropyltriethoxysilane, ethanol, and deionized water for 5 to 10 minutes, and vacuum drying at 110 to 120° C. to obtain a modified polyethylene-based film;

[0014] S23: Take highly water-resistant printing ink, print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 1 to 2 hours, and dry to obtain a finished product.

[0015] Furthermore, in S11, methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane are reacted at a molar ratio of 2:1.

[0016] Furthermore, in S12, the amounts of the components in the polyurethane prepolymer are, by weight, 180 to 200 parts of polyethylene glycol, 100 to 125 parts of isophorone diisocyanate, and 0.8 to 1.1 parts of dibutyltin dilaurate.

[0017] Furthermore, in S12, the amount of silicon-containing diol is 5 to 10% of the total weight of the polyurethane prepolymer.

[0018] Furthermore, in S13, the weight ratio of the silicon-containing polyurethane prepolymer, 1,4-butanediol, 3-allyloxy-1,2-propylene glycol, acetone, and triethylamine is 100:(0.6-0.9):(0.4-0.7):(6-8):(1.5-2.5).

[0019] Furthermore, in S13, the solid content of the silicon-containing polyurethane emulsion is 30-40%.

[0020] Furthermore, in S14, the content of each component in the highly water-resistant printing ink, by weight, is 5 to 7 parts of nano-silicon dioxide, 3 to 5 parts of photoinitiator, 5 to 15 parts of color powder, 60 to 75 parts of silicon-containing polyurethane emulsion, 15 to 25 parts of water, 1 to 2 parts of defoaming agent, 3 to 4 parts of leveling agent, and 2 to 4 parts of dispersant.

[0021] Furthermore, in S21, the corona intensity is 35 to 40 mN / m.

[0022] Furthermore, in S22, the preparation method of the mixed solution of 3-mercaptopropyltriethoxysilane, ethanol and deionized water is: 3-mercaptopropyltriethoxysilane, ethanol and deionized water are mixed in a weight ratio of 1:1:8, dilute hydrochloric acid is added to adjust the pH value to 3-4 and stir at 25-30°C for 10-15 minutes.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses waterborne polyurethane as a binder, and mixes it with toner, nano-silica, photoinitiator, etc. to prepare printing ink. The present invention uses organic silicon to modify waterborne polyurethane, and the specific method is as follows: using methyl allyl alcohol and 1,1,3,3-tetramethyl disiloxane as raw materials, through the addition reaction between silicon-hydrogen bonds and carbon-carbon double bonds, methyl allyl alcohol and 1,1,3,3-tetramethyl disiloxane are reacted in a molar ratio of 2:1 to synthesize silicon-containing diol; using polyethylene glycol and isophorone diisocyanate as raw materials to prepare a polyurethane prepolymer, and then adding silicon-containing diol to obtain a silicon-containing polyurethane prepolymer; and performing a chain extension reaction on the silicon-containing polyurethane prepolymer to obtain a silicon-containing polyurethane emulsion. On the one hand, the addition of silicon-containing diols makes polyurethane have good water resistance, and the ink does not fade or fall off when it comes into contact with water or in a humid environment, thereby improving the printing quality; on the other hand, the siloxane segment in the silicon-containing diol can enhance the gloss of the ink, so that the printed pattern has better appearance and visual appeal.

[0024] In order to further improve the bonding effect between the ink and the printed object (i.e., the polyethylene film); the present invention improves the ink and the printing process. When preparing the polyurethane as a linker in the ink, the present invention mixes 3-allyloxy-1,2-propylene glycol and 1,4-butanediol as a chain extender to introduce carbon-carbon double bonds into the polyurethane molecular chain segment; at the same time, the present invention performs surface treatment on the polyethylene film to introduce thiol groups; the ink prepared by the present invention is coated on the surface of the polyethylene film, and under the action of ultraviolet light irradiation and photoinitiator, the carbon-carbon double bonds on the polyurethane react with the thiol groups on the surface of the polyethylene film to generate a click chemical reaction, thereby improving the bonding force between the ink and the base film.

[0025] It should be noted that, although the addition of silicon-containing diol can improve the water resistance of ink, its dosage also needs to be controlled. Since silicon-containing polyurethane contains hydrophilic segments and hydrophobic segments, the hydrophilic groups in the hydrophilic segments produce hydrogen bonds with water molecules, so that the hydrophilic segments aggregate and wrap the hydrophobic silicon-containing segments to form a stable emulsion; but when the amount of silicon-containing diol is large, the hydrophobic segments wrapped by the hydrophilic segments increase, the emulsion swells and the volume increases, and the incompatibility between the hydrophilic and hydrophobic segments inside the latex particles also increases, the stability of the emulsion deteriorates, resulting in poor performance of the polyurethane, and ultimately affecting the printing effect of the ink; therefore, the present invention controls the addition amount of silicon-containing diol to be 5-10% of the total weight of the polyurethane prepolymer. In addition, because the silicon-containing diol is hydrophobic, and 3-allyloxy-1,2-propylene glycol and 1,4-butanediol are hydrophilic, in order to avoid the two from affecting each other's emulsion stability after mixed addition, the present invention adopts a step-by-step addition method. At the same time, the inventors also consider that the silicon-containing diol has a larger molecular weight, while the small molecular diol is more reactive, has a faster reaction rate, and has a better chain extension effect. Therefore, the silicon-containing diol is added first, and then 3-allyloxy-1,2-propylene glycol and 1,4-butanediol are added. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Materials and sources used in the present invention: nano-silicon dioxide comes from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., with the article number XFI03; the photoinitiator is photoinitiator 907, which comes from Jiangsu Juming Chemical Technology Co., Ltd.; the toner is pigment carbon black, which comes from Rubent Carbon Technology Co., Ltd., model LB502; the polyethylene glycol is polyethylene glycol 2000, which comes from Hai'an Guoli Chemical Co., Ltd.; the defoamer comes from Foshan Nanhai Datian Chemical Co., Ltd., with the article number DT-9825; the leveling agent comes from Germany BYK Chemical, with the article number BYK333; the dispersant is ethylene bislauramide, which comes from Jining Chengrun New Materials Technology Co., Ltd.; the polyethylene base film is the high-density polyethylene label film of Kunshan Zhongsu Special Plastic Film Manufacturing Co., Ltd.

[0028] Embodiment 1: A highly water-resistant printing ink and a printing process thereof, comprising the following steps:

[0029] Step 1:

[0030] S11: Add methyl allyl alcohol to tetrahydrofuran, heat to 60°C, stir for 5 minutes, add isopropanol solution of chloroplatinic acid with a concentration of 0.02 g / mL, keep warm, pass argon, add 1,1,3,3-tetramethyldisiloxane dropwise, and react for 8 hours; remove the solvent tetrahydrofuran by vacuum distillation, and dry at a constant temperature to obtain a silicon-containing diol; wherein methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane react in a molar ratio of 2:1;

[0031] S12: vacuum dehydrating polyethylene glycol at 110° C. for 2 h, taking 185 kg of polyethylene glycol and heating it to 50° C., then adding 113 kg of isophorone diisocyanate and 0.9 kg of dibutyltin dilaurate while keeping warm, stirring for 30 min, heating to 70° C. and reacting for 2 h to obtain a polyurethane prepolymer; adding silicon-containing diol to the polyurethane prepolymer while keeping warm, and continuing the reaction for 1 h to obtain a silicon-containing polyurethane prepolymer; wherein the amount of silicon-containing diol used is 5% of the total weight of the polyurethane prepolymer;

[0032] S13: At 40° C., 0.7 kg of 1,4-butanediol, 0.5 kg of 3-allyloxy-1,2-propylene glycol, and 7 kg of acetone were added to 100 kg of the silicon-containing polyurethane prepolymer to react for 1 hour, 2.3 kg of triethylamine was added to neutralize and react for 30 minutes, deionized water was added to emulsify for 10 minutes, and impurities were evaporated to obtain a silicon-containing polyurethane emulsion with a solid content of 35%;

[0033] S14: 5 g of nano-silicon dioxide, 3 g of photoinitiator, 12 g of toner, 73 g of silicon-containing polyurethane emulsion, 18 g of water, 2 g of defoamer, 3 g of leveling agent, and 3 g of dispersant are mixed evenly, and allowed to stand for defoaming to obtain a highly water-resistant printing ink;

[0034] Step 2:

[0035] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film, with a corona intensity of 35 mN / m; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0036] S22: 3-mercaptopropyltriethoxysilane, ethanol, and deionized water were mixed in a weight ratio of 1:1:8, diluted hydrochloric acid was added to adjust the pH value to 3, and the mixture was stirred at 25° C. for 10 min, and the pretreated polyethylene film was added, immersed for 5 min, and vacuum dried at 110° C. to obtain a modified polyethylene film;

[0037] S23: Take highly water-resistant printing ink and print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 1 hour, and dry to obtain a finished product.

[0038] Embodiment 2: A highly water-resistant printing ink and a printing process thereof, comprising the following steps:

[0039] Step 1:

[0040] S11: adding methyl allyl alcohol to tetrahydrofuran, heating to 65°C, stirring for 8 minutes, adding isopropanol solution of chloroplatinic acid with a concentration of 0.02 g / mL, keeping the temperature and passing argon, adding 1,1,3,3-tetramethyldisiloxane dropwise, and reacting for 10 hours; removing the solvent tetrahydrofuran by vacuum distillation, and drying at a constant temperature to obtain a silicon-containing diol; wherein methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane react in a molar ratio of 2:1;

[0041] S12: vacuum dehydrating polyethylene glycol at 115° C. for 2.5 hours, taking 185 kg of polyethylene glycol and heating it to 55° C., then adding 113 kg of isophorone diisocyanate and 0.9 kg of dibutyltin dilaurate while keeping warm, stirring for 45 minutes, heating to 75° C. and reacting for 2.5 hours to obtain a polyurethane prepolymer; adding silicon-containing diol to the polyurethane prepolymer while keeping warm, and continuing the reaction for 1.5 hours to obtain a silicon-containing polyurethane prepolymer; wherein the amount of silicon-containing diol used is 8% of the total weight of the polyurethane prepolymer;

[0042] S13: At 45° C., 0.7 kg of 1,4-butanediol, 0.5 kg of 3-allyloxy-1,2-propylene glycol, and 7 kg of acetone were added to 100 kg of the silicon-containing polyurethane prepolymer to react for 1.5 hours, 2.3 kg of triethylamine was added to neutralize and react for 30 minutes, deionized water was added to emulsify for 15 minutes, and impurities were evaporated to obtain a silicon-containing polyurethane emulsion with a solid content of 35%;

[0043] S14: 5 g of nano-silicon dioxide, 3 g of photoinitiator, 12 g of toner, 73 g of silicon-containing polyurethane emulsion, 18 g of water, 2 g of defoamer, 3 g of leveling agent, and 3 g of dispersant are mixed evenly, and allowed to stand for defoaming to obtain a highly water-resistant printing ink;

[0044] Step 2:

[0045] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film, with a corona intensity of 38 mN / m; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0046] S22: 3-mercaptopropyltriethoxysilane, ethanol, and deionized water were mixed in a weight ratio of 1:1:8, diluted hydrochloric acid was added to adjust the pH value to 3.5, and the mixture was stirred at 28° C. for 12 minutes, and the pretreated polyethylene film was added, immersed for 7 minutes, and vacuum dried at 115° C. to obtain a modified polyethylene film;

[0047] S23: Take highly water-resistant printing ink and print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 1.5 hours, and dry to obtain a finished product.

[0048] Embodiment 3: A highly water-resistant printing ink and a printing process thereof, comprising the following steps:

[0049] Step 1:

[0050] S11: Add methyl allyl alcohol to tetrahydrofuran, heat to 70°C, stir for 10 minutes, add isopropanol solution of chloroplatinic acid with a concentration of 0.02 g / mL, keep warm, pass argon, add 1,1,3,3-tetramethyldisiloxane dropwise, and react for 12 hours; remove the solvent tetrahydrofuran by vacuum distillation, and dry at a constant temperature to obtain a silicon-containing diol; wherein methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane react in a molar ratio of 2:1;

[0051] S12: vacuum dehydrating polyethylene glycol at 120°C for 3h, taking 185kg of polyethylene glycol and heating it to 60°C, then adding 113kg of isophorone diisocyanate and 0.9kg of dibutyltin dilaurate while keeping warm, stirring for 60min, heating to 80°C and reacting for 3h to obtain a polyurethane prepolymer; adding silicon-containing diol to the polyurethane prepolymer while keeping warm, and continuing the reaction for 2h to obtain a silicon-containing polyurethane prepolymer; wherein the amount of silicon-containing diol used is 10% of the total weight of the polyurethane prepolymer;

[0052] S13: At 50° C., 0.7 kg of 1,4-butanediol, 0.5 kg of 3-allyloxy-1,2-propylene glycol, and 7 kg of acetone were added to 100 kg of the silicon-containing polyurethane prepolymer to react for 2 h, 2.3 kg of triethylamine was added to neutralize and react for 30 min, deionized water was added to emulsify for 15 min, and impurities were evaporated to obtain a silicon-containing polyurethane emulsion with a solid content of 35%;

[0053] S14: 5 g of nano-silicon dioxide, 3 g of photoinitiator, 12 g of toner, 73 g of silicon-containing polyurethane emulsion, 18 g of water, 2 g of defoamer, 3 g of leveling agent, and 3 g of dispersant are mixed evenly, and allowed to stand for defoaming to obtain a highly water-resistant printing ink;

[0054] Step 2:

[0055] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film, with a corona intensity of 40 mN / m; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0056] S22: 3-mercaptopropyltriethoxysilane, ethanol, and deionized water were mixed in a weight ratio of 1:1:8, diluted hydrochloric acid was added to adjust the pH value to 4, and the mixture was stirred at 30° C. for 15 min, and the pretreated polyethylene film was added, immersed for 10 min, and vacuum dried at 120° C. to obtain a modified polyethylene film;

[0057] S23: Take highly water-resistant printing ink and print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 2 hours, and dry to obtain a finished product.

[0058] Comparative Example 1: No silicon-containing diol was added, and other parameters were the same as those in Example 1.

[0059] S11: vacuum dehydrating polyethylene glycol at 110° C. for 2 h, heating 185 kg of polyethylene glycol to 50° C., then adding 113 kg of isophorone diisocyanate and 0.9 kg of dibutyltin dilaurate while keeping the temperature, stirring for 30 min, heating to 70° C. for reaction for 2 h, and obtaining a polyurethane prepolymer;

[0060] S12: At 40° C., 0.7 kg of 1,4-butanediol, 0.5 kg of 3-allyloxy-1,2-propylene glycol, and 7 kg of acetone were added to 100 kg of polyurethane prepolymer for reaction for 1 hour, 2.3 kg of triethylamine was added for neutralization reaction for 30 minutes, deionized water was added for emulsification for 10 minutes, and impurities were evaporated to obtain a polyurethane emulsion with a solid content of 35%;

[0061] S13: 5 g of nano-silicon dioxide, 3 g of photoinitiator, 12 g of toner, 73 g of polyurethane emulsion, 18 g of water, 2 g of defoamer, 3 g of leveling agent, and 3 g of dispersant are mixed evenly, and allowed to stand for defoaming to obtain printing ink;

[0062] Step 2:

[0063] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film, with a corona intensity of 35 mN / m; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0064] S22: 3-mercaptopropyltriethoxysilane, ethanol, and deionized water were mixed in a weight ratio of 1:1:8, diluted hydrochloric acid was added to adjust the pH value to 3, and the mixture was stirred at 25° C. for 10 min, and the pretreated polyethylene film was added, immersed for 5 min, and vacuum dried at 110° C. to obtain a modified polyethylene film;

[0065] S23: Printing ink is taken and printed on the surface of the modified polyethylene base film to form a printing ink layer, which is cured by UV light for 1 hour and dried to obtain a finished product.

[0066] Comparative Example 2: Silicon-containing diol, 1,4-butanediol and 3-allyloxy-1,2-propylene glycol were added to the polyurethane prepolymer at the same time, and the other parameters were the same as those in Example 2.

[0067] Step 1:

[0068] S11: adding methyl allyl alcohol to tetrahydrofuran, heating to 65°C, stirring for 8 minutes, adding isopropanol solution of chloroplatinic acid with a concentration of 0.02 g / mL, keeping the temperature and passing argon, adding 1,1,3,3-tetramethyldisiloxane dropwise, and reacting for 10 hours; removing the solvent tetrahydrofuran by vacuum distillation, and drying at a constant temperature to obtain a silicon-containing diol; wherein methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane react in a molar ratio of 2:1;

[0069] S12: vacuum dehydrating polyethylene glycol at 115° C. for 2.5 h, taking 185 kg of polyethylene glycol and heating it to 55° C., then adding 113 kg of isophorone diisocyanate and 0.9 kg of dibutyltin dilaurate while keeping the temperature, stirring for 45 min, and heating it to 75° C. for reaction for 2.5 h to obtain a polyurethane prepolymer;

[0070] S13: adding silicon-containing diol to the polyurethane prepolymer at 45°C to obtain a mixed material; wherein the amount of silicon-containing diol is 8% of the total weight of the polyurethane prepolymer; adding 0.7kg 1,4-butanediol, 0.5kg 3-allyloxy-1,2-propylene glycol, and 7kg acetone to 100kg of the mixed material to react for 1.5h, adding 2.3kg triethylamine to neutralize and react for 30min, adding deionized water to emulsify for 15min, and evaporating impurities to obtain a silicon-containing polyurethane emulsion with a solid content of 35%;

[0071] S14: 5 g of nano-silicon dioxide, 3 g of photoinitiator, 12 g of toner, 73 g of silicon-containing polyurethane emulsion, 18 g of water, 2 g of defoamer, 3 g of leveling agent, and 3 g of dispersant are mixed evenly, and allowed to stand for defoaming to obtain a highly water-resistant printing ink;

[0072] Step 2:

[0073] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film, with a corona intensity of 38 mN / m; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0074] S22: 3-mercaptopropyltriethoxysilane, ethanol, and deionized water were mixed in a weight ratio of 1:1:8, diluted hydrochloric acid was added to adjust the pH value to 3.5, and the mixture was stirred at 28° C. for 12 minutes, and the pretreated polyethylene film was added, immersed for 7 minutes, and vacuum dried at 115° C. to obtain a modified polyethylene film;

[0075] S23: Take highly water-resistant printing ink and print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 1.5 hours, and dry to obtain a finished product.

[0076] Comparative Example 3: The dosage of the silicon-containing diol was increased, and the other parameters were the same as those in Example 3.

[0077] Step 1:

[0078] S11: Add methyl allyl alcohol to tetrahydrofuran, heat to 70°C, stir for 10 minutes, add isopropanol solution of chloroplatinic acid with a concentration of 0.02 g / mL, keep warm, pass argon, add 1,1,3,3-tetramethyldisiloxane dropwise, and react for 12 hours; remove the solvent tetrahydrofuran by vacuum distillation, and dry at a constant temperature to obtain a silicon-containing diol; wherein methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane react in a molar ratio of 2:1;

[0079] S12: vacuum dehydrating polyethylene glycol at 120°C for 3h, taking 185kg polyethylene glycol and heating it to 60°C, then adding 113kg isophorone diisocyanate and 0.9kg dibutyltin dilaurate while keeping warm, stirring for 60min, heating to 80°C for reaction for 3h to obtain a polyurethane prepolymer; adding silicon-containing diol to the polyurethane prepolymer while keeping warm, and continuing the reaction for 2h to obtain a silicon-containing polyurethane prepolymer; wherein the amount of silicon-containing diol used is 15% of the total weight of the polyurethane prepolymer;

[0080] S13: At 50° C., 0.7 kg of 1,4-butanediol, 0.5 kg of 3-allyloxy-1,2-propylene glycol, and 7 kg of acetone were added to 100 kg of the silicon-containing polyurethane prepolymer to react for 2 h, 2.3 kg of triethylamine was added to neutralize and react for 30 min, deionized water was added to emulsify for 15 min, and impurities were evaporated to obtain a silicon-containing polyurethane emulsion with a solid content of 35%;

[0081] S14: 5 g of nano-silicon dioxide, 3 g of photoinitiator, 12 g of toner, 73 g of silicon-containing polyurethane emulsion, 18 g of water, 2 g of defoamer, 3 g of leveling agent, and 3 g of dispersant are mixed evenly, and allowed to stand for defoaming to obtain a highly water-resistant printing ink;

[0082] Step 2:

[0083] S21: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film, with a corona intensity of 40 mN / m; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film;

[0084] S22: 3-mercaptopropyltriethoxysilane, ethanol, and deionized water were mixed in a weight ratio of 1:1:8, diluted hydrochloric acid was added to adjust the pH value to 4, and the mixture was stirred at 30° C. for 15 min, and the pretreated polyethylene film was added, immersed for 10 min, and vacuum dried at 120° C. to obtain a modified polyethylene film;

[0085] S23: Take highly water-resistant printing ink and print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 2 hours, and dry to obtain a finished product.

[0086] Experiment: Using the methods in Examples 1 to 3 and Comparative Examples 1 to 3, print ink on the surface of the polyethylene film to form a sample with a 2cm×2cm pattern. The samples were tested for water resistance and adhesion performance respectively. Among them, the test method for water resistance is: soak the finished product in deionized water at 30°C for 120 hours, and observe the apparent morphology of the ink pattern on the surface of the finished product after taking it out; the test method for adhesion performance is: at 30°C, the T-type peel strength between the ink and the polyethylene film in the sample is tested by a tensile testing machine, the tensile rate is 200mm / min, each sample is tested 3 times, and the average value is taken; ink shedding: wrap a 200g weight with a cotton cloth soaked in a 20% alcohol aqueous solution, wipe back and forth on the ink printed on the finished product 100 times (one back and forth is counted as one time), and after wiping, use the table method to calculate the ink shedding area on the sample surface to find the ink shedding rate. The experimental results are shown in the following table.

[0087]

[0088]

[0089] Conclusion: The data of Examples 1 to 3 show that the ink prepared by the present invention has good performance. The results of Example 1 and Comparative Example 1 show that after the introduction of silicon-containing diol, the ink does not bubble or fall off after the sample is immersed in water for 120 hours. After wiping with ethanol aqueous solution, the pattern is intact and does not fall off, and the ink has strong water resistance. The data results of Example 2 and Comparative Example 2 show that when silicon-containing diol is added simultaneously with 1,4-butanediol and 3-allyloxy-1,2-propylene glycol, the performance of the obtained silicon-containing polyurethane decreases, resulting in poor printing effect of the ink. The results of Example 3 and Comparative Example 3 show that after increasing the amount of silicon-containing diol in Comparative Example 3, although the ink still has good water resistance, due to the large particles of the prepared polyurethane latex and the poor stability of the emulsion as in Example 3, the polyurethane particles are easy to precipitate and aggregate, thereby affecting its dispersion performance, and ultimately making it difficult for the ink to be evenly coated on the surface of the base film during printing, resulting in poor adhesion of the ink.

[0090] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a highly water-resistant printing ink, characterized in that: By weight, 5-7 parts of nano-silicon dioxide, 3-5 parts of photoinitiator, 5-15 parts of toner, 60-75 parts of silicon-containing polyurethane emulsion, 15-25 parts of water, 1-2 parts of defoamer, 3-4 parts of leveling agent, and 2-4 parts of dispersant are mixed, and allowed to stand for defoaming to obtain a highly water-resistant printing ink; The method for preparing the silicon-containing polyurethane emulsion comprises the following steps: S1: Add methyl allyl alcohol to tetrahydrofuran, heat to 60-70°C, stir for 5-10 min, add isopropanol solution of chloroplatinic acid with a concentration of 0.02-0.03 g / mL, keep warm, pass argon, add 1,1,3,3-tetramethyldisiloxane dropwise, and react for 8-12 h; remove the solvent tetrahydrofuran by vacuum distillation, and dry at a constant temperature to obtain silicon-containing diol; S2: vacuum dehydrating polyethylene glycol at 110-120°C for 2-3h, heating polyethylene glycol to 50-60°C, then adding isophorone diisocyanate and dibutyltin dilaurate while keeping warm, stirring for 30-60min, heating to 70-80°C for reaction for 2-3h to obtain a polyurethane prepolymer; adding silicon-containing diol to the polyurethane prepolymer while keeping warm, and continuing the reaction for 1-2h to obtain a silicon-containing polyurethane prepolymer; the amount of silicon-containing diol used is 5-10% of the total weight of the polyurethane prepolymer; S3: At 40-50°C, add 1,4-butanediol, 3-allyloxy-1,2-propylene glycol and acetone to the silicon-containing polyurethane prepolymer and react for 1-2 hours, add triethylamine to neutralize and react for 30 minutes, add deionized water to emulsify for 10-15 minutes, and evaporate impurities to obtain a silicon-containing polyurethane emulsion.

2. The method for preparing a highly water-resistant printing ink according to claim 1, characterized in that: In S1, methyl allyl alcohol and 1,1,3,3-tetramethyldisiloxane are reacted in a molar ratio of 2:

1.

3. The method for preparing a highly water-resistant printing ink according to claim 1, characterized in that: In S2, in the polyurethane prepolymer, the amount of each component is 180-200 parts of polyethylene glycol, 100-125 parts of isophorone diisocyanate, and 0.8-1.1 parts of dibutyltin dilaurate.

4. The method for preparing a highly water-resistant printing ink according to claim 1, characterized in that: In S3, the weight ratio of the silicon-containing polyurethane prepolymer, 1,4-butanediol, 3-allyloxy-1,2-propylene glycol, acetone, and triethylamine is 100:(0.6~0.9):(0.4~0.7):(6~8):(1.5~2.5); the solid content of the silicon-containing polyurethane emulsion is 30~40%.

5. A highly water-resistant printing ink prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the highly water-resistant printing ink as claimed in claim 5 in a printing process, characterized in that: The following steps are involved: Step 1: taking a polyethylene film, cleaning the surface of the polyethylene film with anhydrous ethanol, and drying at a constant temperature; performing a corona treatment on the surface of the polyethylene film; cleaning the polyethylene film after the corona treatment with deionized water, and drying at a constant temperature to obtain a pretreated polyethylene film; Step 2: immersing the pretreated polyethylene-based film in a mixed solution of 3-mercaptopropyltriethoxysilane, ethanol, and deionized water for 5 to 10 minutes, and vacuum drying at 110 to 120° C. to obtain a modified polyethylene-based film; Step 3: Take highly water-resistant printing ink and print it on the surface of the modified polyethylene base film to form a printing ink layer, UV light cure for 1 to 2 hours, and dry to obtain a finished product.

7. The use according to claim 6, characterized in that: In step 1, the corona intensity is 35-40 mN / m.

8. The use according to claim 6, characterized in that: In step 2, the mixed solution of 3-mercaptopropyltriethoxysilane, ethanol and deionized water is prepared by taking 3-mercaptopropyltriethoxysilane, ethanol and deionized water, mixing them in a weight ratio of 1:1:8, adding dilute hydrochloric acid to adjust the pH value to 3-4 and stirring at 25-30°C for 10-15 minutes.

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