Low-migration low-odor UV curing flexible printing ink and preparation method thereof

Abstract

The invention discloses low-migration low-odor UV (ultraviolet) curing flexible printing ink. The low-migration low-odor UV curing flexible printing ink is prepared from components in parts by weight as follows: 20-50 parts of epoxy acrylate, 3-8 parts of organosilicon acrylate, 5-15 parts of acrylated hyperbranched polyesteramide, 10-15 parts of liquid crystal diacrylate, 20-50 parts of a photocuring monomer, 5-15 parts of a photoinitiator, 15-45 parts of pigment and 1-8 parts of talcum powder, the photocuring monomer is any one of ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate and trimethylolpropane triacrylate, and the photoinitiator is one or more of a photoinitiator TPO-L, a photoinitiator 819 and a photoinitiator 184; the printing ink prepared from the components has the characteristics of less harmful substance precipitation, no pungent smell, excellent wear resistance and difficulty in shedding.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of inks, in particular to a low-migration and low-odor UV-cured flexographic ink and a preparation method thereof. BACKGROUND

[0002] As an environmentally friendly ink variety currently attracting much attention, UV-cured ink shows broad application prospects and development potential due to its remarkable advantages such as energy saving, environmental friendliness and efficient curing. The ink is usually composed of a prepolymer, active monomers, a photoinitiator, a diluent and various functional additives. Under irradiation of ultraviolet light of a specific wavelength, the photoinitiator rapidly decomposes to generate free radicals or cations, which in turn initiates the polymerization and crosslinking reaction of unsaturated double bonds in the system, forming a stable three-dimensional network structure. The structure endows the ink with excellent adhesion to the surface of various printing materials, and good chemical resistance and physical durability, so the UV ink is suitable for paper, plastic, tape, circuit board, chrome plate, electronic components and metal and other fields.

[0003] Although the UV-cured ink has the above-mentioned advantages, there are still some technical problems to be further overcome. These include that unreacted monomers or photoinitiator decomposition products in the formula may migrate to the contact medium, posing a health and safety risk; some active diluents and photoinitiator by-products release a significant irritating odor, affecting the working environment and product applicability; under the long-term action of mechanical external force, the wear resistance of the ink layer is still insufficient, and surface wear or scratches may easily occur; in addition, under specific substrates or harsh use conditions, the adhesion between the ink layer and the printing material may decrease, leading to partial or overall peeling, affecting the service life and appearance quality of the printed product. SUMMARY

[0004] In order to improve the problems of harmful substance emission, irritating odor, insufficient wear resistance and peeling of traditional UV-cured ink, a low-migration and low-odor UV-cured flexographic ink and a preparation method thereof are provided.

[0005] The above-mentioned application purpose of the application is realized by the following technical scheme: A low-migration and low-odor UV-cured flexographic ink comprises the following components by weight: epoxy acrylate 20-50 parts, silicone acrylate 3-8 parts, acrylated hyperbranched polyester amide 5-15 parts, liquid crystal diacrylate 10-15 parts, photocurable monomer 20-50 parts, photoinitiator 5-15 parts, pigment 15-45 parts, Talc 1-8 parts; The photo-curable monomer is any one of ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate, The photo-initiator is one or more of photo-initiator TPO-L, photo-initiator 819, and photo-initiator 184.

[0006] By adopting the above technical solution, the epoxy acrylate is used as the main film-forming resin, the acrylate groups in the molecule of the epoxy acrylate undergo radical polymerization under the action of the photo-initiator, a three-dimensional network structure with high cross-linking density is formed, the adhesion is enhanced, and the migration of small molecules is reduced; The organic silicone acrylate introduces a siloxane chain segment, and the coating is endowed with flexibility and low surface energy, the friction coefficient is reduced, and the wear resistance is improved; The acrylated hyperbranched polyester amide has a highly branched structure, a large number of terminal functional groups, and an internal cavity, a large number of terminal acrylate groups of the acrylated hyperbranched polyester amide actively participate in cross-linking during curing, the cross-linking density of the cured film is improved, the network density is increased, the movement of small molecule monomers, oligomers, or photolysis products that participate in the reaction or do not completely react is limited, and their migration to the outside of the coating is hindered, the network density is also helpful to reduce the internal stress caused by curing shrinkage, so that the coating is not easy to fall off due to bending and scratching, the internal cavity structure plays a coating role, the pigment fixation is enhanced, and bleeding is reduced, the amide groups form firm hydrogen bonds with the nitrogen-containing heterocyclic groups, carbonyl groups, or hydroxyl groups on the surface of the pigment, and the migration of the pigment caused by poor interfacial bonding is reduced; The liquid crystal diacrylate is a special monomer containing a rigid mesogenic unit (biphenyl or benzene ring) and a terminal acrylate group, in the liquid state of the ink before curing, the liquid crystal diacrylate molecules are arranged in an orderly manner along a direction, when the UV light initiates curing, the volume shrinkage from liquid to solid is low, the internal stress caused by the volume shrinkage is reduced, the ink layer after curing is not easy to fall off, the polymerization reaction of the orderly arranged acrylate groups will limit the orderly liquid crystal state in the cross-linked polymer network, form a rigid molecular chain arranged in an orderly and compact manner, reduce the free volume and intermolecular gap in the polymer network, hinder the diffusion path of unreacted monomers and photo-initiator degradation products, the bond force along the molecular chain axis direction is much stronger than the van der Waals force between chains, when an external force acts on the ink layer after curing, the network composed of the orderly arranged rigid chains can more effectively disperse and withstand stress, and the hardness is improved; The rigid mesogenic unit of the liquid crystal diacrylate is affected by the steric hindrance and polar interaction on the surface of the hyperbranched molecule, and is more inclined to be arranged in an orderly manner along the surface of the hyperbranched molecule or in the branch gap thereof, and the formation and stability of the liquid crystal phase are strengthened; Photocurable monomers such as ethoxylated trimethylolpropane triacrylate and other multifunctional monomers adjust viscosity and increase crosslinking points, photoinitiators ensure rapid and thorough curing, pigments provide color, and talc is used as a filler to enhance hardness and wear resistance. Epoxy acrylate and silicone acrylate form a basic network, hyperbranched polyester amide and liquid crystal diacrylate jointly enhance the crosslinking density and order, and photocurable monomer and photoinitiator optimize the reaction efficiency, forming a dense coating overall. In summary, the ink exhibits low migration, low odor, abrasion resistance, and is not easily detached.

[0007] Optionally, the photoinitiator is photoinitiator TPO-L or photoinitiator 819.

[0008] By adopting the above technical solutions, photoinitiator TPO-L (acylphosphine oxide) is suitable for surface curing, while photoinitiator 819 (diacylphosphine oxide) is more conducive to deep curing, so that the ink is uniformly cured from the surface to the inside, reducing the curing gradient, thereby minimizing the residue of unreacted monomers, resulting in low migration, low odor, abrasion resistance, and less flaking.

[0009] Optionally, the mass ratio of photoinitiator TPO-L to photoinitiator 819 is (1~2):1.

[0010] By adopting the above technical solution, this ratio avoids excessively rapid surface curing leading to oxygen inhibition or insufficient deep curing, allowing the two to better exert their synergistic effect.

[0011] Optionally, the pigment can be any one of pigment blue 15:1, pigment red 57:1, pigment yellow 14, or pigment orange 64.

[0012] By adopting the above technical solutions, these pigments are all stabilized organic pigments with compact molecular structures and moderate polarity. They are compatible with acrylic resins and do not easily migrate in the system. The rich variety of raw materials makes them more suitable for various color requirements and expands the application scope.

[0013] Optionally, the talc powder is modified with a silane coupling agent containing acryloyloxy group.

[0014] By adopting the above technical solution, talc powder is modified by a silane coupling agent containing acryloyloxy groups. One end of the coupling agent molecule is combined with the hydroxyl groups on the surface of talc powder, and the other end introduces acryloyloxy groups, so that talc powder can copolymerize with acrylate resin during UV curing to form chemical bonds, enhance the interfacial bonding force between filler and resin, reduce interfacial defects and micropores, improve wear resistance and adhesion, and reduce the risk of peeling.

[0015] Optionally, the silane coupling agent containing acryloyloxy group is γ-methacryloyloxypropyltrimethoxysilane.

[0016] By adopting the above technical solution, the methacryloyloxy group has strong copolymerization with the acrylate system. After the methoxy group is hydrolyzed, it is firmly bonded to the surface of talc powder, making the talc powder more uniformly dispersed and participating in the curing network, forming a stronger interface, improving the chemical resistance of the coating, and reducing migration caused by interface weakening.

[0017] Optionally, 0.2 to 1 part of polyether-modified polysiloxane may also be added to the components.

[0018] By adopting the above technical solutions, the surface tension of the ink can be reduced, the leveling and defoaming ability can be improved, the coating can be made more uniform and dense, and the points that may become migration pathways such as bubbles and defects can be reduced. Polysiloxane segments may migrate to the surface, providing additional lubrication and improving wear resistance. Its low volatility helps to reduce odor.

[0019] The second objective of this invention is achieved through the following technical solution: The preparation method of the above-mentioned low-migration, low-odor UV-curable flexographic ink includes the following steps: S1: Epoxy acrylate, silicone acrylate, acrylated hyperbranched polyester amide, talc and pigment are first premixed and then dispersed to obtain a dispersion slurry; S2: The dispersion slurry is milled, and then all components except epoxy acrylate, silicone acrylate, acrylated hyperbranched polyester amide, talc and pigment are added. After stirring and mixing, the ink is obtained.

[0020] By adopting the above technical solution, the preparation method first premixes epoxy acrylate, silicone acrylate, acrylated hyperbranched polyester amide, talc powder and pigment, and then disperses and mills them. This step ensures that the pigment and filler are fully dispersed, avoids agglomeration, and makes the reaction uniform and dense network during curing. Then, photoinitiators and other components are added to avoid premature polymerization caused by thermal or mechanical stress during milling, ensure curing efficiency, optimize dispersibility, improve the overall coating quality, and reduce uncured points.

[0021] In summary, this application has at least the following beneficial effects: (1) Acrylate-esterified hyperbranched polyester amide has a highly branched structure, etc. The terminal acrylate groups increase the crosslinking density, hinder the migration of small molecules, reduce internal stress, and the cavity enhances pigment fixation, reduces migration, and enhances adhesion and wear resistance. (2) Liquid crystal diacrylate contains rigid mesocrystalline units and terminal acrylate groups. During curing, it has low volume shrinkage and low internal stress, and can form an ordered and tightly arranged rigid chain, which increases hardness and hinders the diffusion of substances. (3) Through the synergistic effect of components, the migration of harmful substances and irritating odor are reduced, the wear resistance and adhesion of the ink layer are improved, and it is not easy to fall off. Detailed Implementation

[0022] raw material Epoxy acrylate, brand name Sartomer CN104NS, purchased from Shanghai Buding Chemical Co., Ltd. Organosilicon acrylate, brand name Xinno® WE-D1200, was purchased from Anhui Jiazhi Xinno Chemical Co., Ltd. Liquid crystal diacrylate, grade RM257, purity ≥98wt%, purchased from Shanghai Yuanye Biotechnology Co., Ltd. Talc powder, grade TP-888AW, SiO2 content 59wt%, D50 5µm, purchased from Haicheng Hetai Powder Technology Co., Ltd. Pigment Blue 15:1, Pigment Red 57:1, Pigment Yellow 14 and Pigment Orange 64 were all purchased from Shenzhen Coating New Materials Co., Ltd. Ethoxylated trimethylolpropane triacrylate was purchased from Wuhan Maikairui Chemical Co., Ltd. Pentaerythritol triacrylate, purity ≥80wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Trimethylolpropane triacrylate, purity ≥85wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. The photoinitiators TPO-L (purity ≥ 99.0 wt%), 819 (purity ≥ 99.0 wt%), and 184 (purity ≥ 99.0 wt%) were all purchased from Nanjing Milan Chemical Co., Ltd. The polyether-modified polysiloxane, brand name SiFast® SF-737, was purchased from Guangdong Biaomei Silicon Fluorine New Materials Co., Ltd. γ-Methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and 3-(acryloyloxy)propyltrimethoxysilane were all purchased from Hangzhou Jessica Chemical Co., Ltd. Succinic anhydride (purity ≥ 99 wt%), acryloyl chloride (purity ≥ 96 wt%), p-toluenesulfonic acid (purity ≥ 98 wt%), and p-methoxyphenol (4-methoxyphenol, purity ≥ 98 wt%) were all purchased from Shanghai Yuanye Biotechnology Co., Ltd. Diethanolamine (purity ≥ 99 wt%) and triethylamine (purity ≥ 99.5 wt%) were both purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Toluene, glacial acetic acid, and anhydrous ethanol were all sourced from commercially available sources.

[0023] Preparation Example 1 A modified talc powder is prepared as follows: 10.8 kg of deionized water and 1.2 kg of anhydrous ethanol are stirred at 100 rpm for 5 min to obtain a mixed solvent. Glacial acetic acid is added dropwise to adjust the mixed solvent to 4.5 ± 0.1. 150 g of γ-methacryloxypropyltrimethoxysilane is added to the mixed solvent and stirred continuously at 500 rpm for 45 min to obtain an aqueous solution of γ-methacryloxypropyltrimethoxysilane in ethanol. 10 kg of talc powder was added to an aqueous solution of γ-methacryloxypropyltrimethoxysilane ethanol, and the temperature was adjusted to 75℃±2℃. The mixture was stirred at 120 rpm for 3 hours at this temperature. The reacted material was then naturally cooled to 40℃ to obtain a slurry. The slurry was fed into a vacuum filter to obtain a filter cake. The filter cake was washed three times with deionized water and then dried in a drying oven at 100°C for 8 hours to obtain modified talc powder.

[0024] Preparation Example 2 A modified talc powder, which differs from Preparation Example 1 in that: γ-aminopropyltriethoxysilane is used in place of γ-methacryloyloxypropyltrimethoxysilane by an equal mass; the rest is the same as Preparation Example 1.

[0025] Preparation Example 3 A modified talc powder, which differs from Preparation Example 1 in that: 3-(acryloyloxy)propyltrimethoxysilane is used in place of γ-methacryloyloxypropyltrimethoxysilane by an equal mass; the rest is the same as Preparation Example 1.

[0026] Preparation Example 4 An acrylated hyperbranched polyester amide is prepared as follows: 10 kg of succinic anhydride and 86 g of p-toluenesulfonic acid are added to a reaction vessel, the reaction system is sealed, nitrogen gas is purged into the vessel at a flow rate of 10 L / min for 5 min, and then the vent valve is opened to exhaust the gas. The nitrogen purging and venting steps are repeated 3 times. The mixture is stirred at 30 rpm, and the temperature is increased to 80±2℃ at a rate of 2℃ / min. The reaction is maintained at 30 rpm and 80±2℃ for 30 min. Maintain the temperature inside the reactor at 80±2℃, and continuously add 10.5 kg of diethanolamine to the reactor at a rate of 40 mL / min. After the addition is complete, raise the temperature to 90±2℃ and maintain the reaction at this temperature for 2 hours. The temperature was raised to 120±2℃, the vacuum pump was turned on, and the pressure in the reaction system was reduced to -0.095MPa. The reaction was carried out at 120±2℃ and -0.095MPa for 3 hours. The acid value was measured to be 18mg KOH / g. The reaction was stopped to obtain a hyperbranched polyester amide intermediate with hydroxyl groups at the end. All the obtained hyperbranched polyester amide intermediates with hydroxyl terminals were added to the reactor, followed by 110g of p-methoxyphenol and 25kg of toluene. The mixture was stirred at 50 rpm, the reaction system was sealed, and nitrogen gas was purged into the reactor at a flow rate of 10L / min for 5 minutes. Then the vent valve was opened to vent the gas. The nitrogen purging and venting steps were repeated 3 times. The cooling system was then turned on to cool the material to 3℃. Maintaining a temperature of 3°C and a rotation speed of 50 rpm, 10.2 kg of acryloyl chloride and 12.0 kg of triethylamine were mixed and added dropwise to the reactor at a rate of 60 mL / min. After the addition was completed, stirring was continued for 1 hour. Stop cooling and allow the temperature to rise naturally to room temperature (25±2℃). Continue stirring at 50 rpm for 8 hours at room temperature. After the reaction is complete, filter the solution using a pressure filter to obtain the filtrate. Transfer the filtrate to an extraction separation vessel and separate the liquid to obtain the organic phase. First, heat the solution to 80℃ and distill for 30 minutes, then distill at 55℃ and -0.095 MPa for 1 hour, followed by vacuum distillation at 60℃ and -0.098 MPa for 1 hour. Stop heating and allow the solution to cool naturally to 40℃ to obtain acrylated hyperbranched polyester amide.

[0027] Example 1 A low-migration, low-odor UV-curable flexographic ink is prepared from the following components by weight: 35 kg of epoxy acrylate, 5 kg of silicone acrylate, 10 kg of acrylated hyperbranched polyesteramide, 4 kg of modified talc, 30 kg of pigment blue 15:1, 35 kg of ethoxylated trimethylolpropane triacrylate, 6 kg of photoinitiator TPO-L, 4 kg of photoinitiator 819, 12 kg of liquid crystal diacrylate, and 0.5 kg of polyether-modified polysiloxane, wherein the modified talc is derived from Preparation Example 1, and the acrylated hyperbranched polyesteramide is derived from Preparation Example 4.

[0028] Its preparation method is as follows: S1: Epoxy acrylate, silicone acrylate, acrylated hyperbranched polyester amide, talc, and pigment blue are added sequentially to a disperser in a 15:1 ratio. The mixture is stirred at 200 rpm for 10 min and then dispersed at 1500 rpm for 20 min to obtain a dispersion slurry. S2: Transfer the dispersed slurry to a ball mill for grinding at 250 rpm for 3 hours. Transfer the ground slurry to a mixing vessel and add ethoxylated trimethylolpropane triacrylate, photoinitiator TPO-L, photoinitiator 819, liquid crystal diacrylate, and polyether-modified polysiloxane in sequence. Stir at 500 rpm for 15 minutes to obtain low-migration, low-odor UV-curable flexographic ink.

[0029] Comparative Example 1 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it does not contain acrylated hyperbranched polyesteramide; the rest is the same as Example 1.

[0030] Comparative Example 2 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it does not contain liquid crystal diacrylate; the rest is the same as Example 1.

[0031] Example 2 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses pentaerythritol triacrylate in place of ethoxylated trimethylolpropane triacrylate; the rest is the same as in Example 1.

[0032] Example 3 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses an equal mass of trimethylolpropane triacrylate instead of ethoxylated trimethylolpropane triacrylate; the rest is the same as in Example 1.

[0033] Example 4 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses photoinitiator 184 in place of photoinitiator TPO-L; the rest is the same as in Example 1.

[0034] Example 5 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses photoinitiator 184 in place of photoinitiator 819 by mass; the rest is the same as in Example 1.

[0035] Example 6 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: no photoinitiator TPO-L is added, and the photoinitiator 819 is 10 kg; the rest is the same as Example 1.

[0036] Example 7 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it does not contain photoinitiator 819, and the photoinitiator TPO-L is 10 kg; the rest is the same as Example 1.

[0037] Example 8 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it does not contain photoinitiator 819 and photoinitiator TPO-L, and the amount of photoinitiator 184 is 10 kg; the rest is the same as in Example 1.

[0038] Example 9 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: 4 photoinitiator 184 is added, and the amount of photoinitiator TPO-L is 3.6 kg and the amount of photoinitiator 819 is 2.4 kg; the rest is the same as in Example 1.

[0039] Example 10 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: the photoinitiator TPO-L is 5 kg and the photoinitiator 819 is 5 kg; the rest is the same as in Example 1.

[0040] Example 11 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: the photoinitiator TPO-L is 7.5 kg and the photoinitiator 819 is 2.5 kg; the rest is the same as in Example 1.

[0041] Example 12 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: the photoinitiator TPO-L is 8 kg and the photoinitiator 819 is 2 kg; the rest is the same as in Example 1.

[0042] Example 13 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: the photoinitiator TPO-L is 4 kg and the photoinitiator 819 is 6 kg; the rest is the same as in Example 1.

[0043] Example 14 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses Pigment Red 57:1 in an equal mass ratio to replace Pigment Blue 15:1; the rest is the same as in Example 1.

[0044] Example 15 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses Pigment Yellow 14 in a mass ratio of 15:1 instead of Pigment Blue; the rest is the same as in Example 1.

[0045] Example 16 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses Pigment Orange 64 in a mass ratio of 15:1 instead of Pigment Blue; the rest is the same as in Example 1.

[0046] Example 17 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it uses talc powder of equal mass instead of modified talc powder; the rest is the same as Example 1.

[0047] Example 18 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that the modified talc powder is derived from Preparation Example 2; the rest is the same as Example 1.

[0048] Example 19 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that the modified talc powder is derived from Preparation Example 3; the rest is the same as Example 1.

[0049] Example 20 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that it does not contain polyether-modified polysiloxane; the rest is the same as Example 1.

[0050] Example 21 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: 20 kg of epoxy acrylate, 3 kg of silicone acrylate, 5 kg of acrylated hyperbranched polyesteramide, 1 kg of modified talc, 15 kg of pigment blue 15:1, 20 kg of ethoxylated trimethylolpropane triacrylate, 3 kg of photoinitiator TPO-L, 2 kg of photoinitiator 819, 10 kg of liquid crystal diacrylate, and 0.2 kg of polyether-modified polysiloxane; the remaining components are the same as in Example 1.

[0051] Example 22 A low-migration, low-odor UV-curable flexographic ink differs from Example 1 in that: 50 kg of epoxy acrylate, 8 kg of silicone acrylate, 15 kg of acrylated hyperbranched polyesteramide, 8 kg of modified talc, 45 kg of pigment blue 15:1, 50 kg of ethoxylated trimethylolpropane triacrylate, 9 kg of photoinitiator TPO-L, 8196 kg of photoinitiator 8196 kg, 15 kg of liquid crystal diacrylate, and 1 kg of polyether-modified polysiloxane; the remaining components are the same as in Example 1.

[0052] The inks of Examples 1-22 and Comparative Examples 1-2 were printed onto a PET substrate to a thickness of 10µm, and then treated with 30mW / cm² ink. 2 The ink layers were cured under ultraviolet light for 60 seconds to form an ink layer. The ink layers formed in Examples 1-22 and Comparative Examples 1-2 were tested.

[0053] 1. Abrasion resistance: The abrasion resistance was tested according to GB / T 7707-2008 "Gravure Decorative Printing Materials", and the test results are shown in Table 1.

[0054] Table 1. Test results of ink abrasion resistance.

[0055] 2. Release of harmful substances: The cured ink samples were cut to 50mm×50mm and placed in water, alcohol and grease respectively. They were soaked at 40℃ for 10 days. After soaking, the mass of the dried residue was measured, and the mass loss rate was calculated. The test results are shown in Table 2.

[0056] Table 2 Results of Hazardous Substance Emission Detection (Mass Loss Rate, %)

[0057] 3. Shedding: The cured ink sample was folded 180° and the number of folds during which the ink layer burst was recorded. The test results are shown in Table 3. The adhesion level was recorded according to ISO 2409-2020 "Paints and varnishes - Cross-cut test". The lower the adhesion level, the less likely it is to peel off. The test results are shown in Table 3.

[0058] Table 3 Results of shedding performance test

[0059] 4. Odor: The cured ink samples were heated at 50°C for 15 minutes. 100 people aged 25-35 were selected to smell the inks and the number of people who thought they had an irritating odor was recorded. Half of the 100 people were female and half were male. More than 95 people thought that the inks of Examples 1-22 had no irritating odor, while more than 20 people thought that the inks of Comparative Examples 1-2 had an irritating odor.

[0060] Based on Tables 1-3, the analyses of Examples 1-22 and Comparative Examples 1-2 are as follows: Compared with Example 1, the wear amount of Example 1 is less than that of Comparative Example 1. The mass loss rate of Example 1 after being soaked in water, alcohol and grease is less than that of Comparative Example 1 after being soaked in water, alcohol and grease. The number of folds in Example 1 is greater than that in Comparative Example 1. The adhesion level of Example 1 is lower than that of Comparative Example 1.

[0061] The difference between Example 1 and Comparative Example 1 is that Example 1 adds acrylated hyperbranched polyester amide. Acrylated hyperbranched polyester amide has a highly branched structure, a large number of terminal functional groups and internal cavities. The terminal groups increase the crosslinking density and restrict the migration of small molecules. The cavity coating enhances the fixation of pigments. The amide groups form hydrogen bonds with the pigments, reducing pigment migration and shedding. Therefore, it is necessary to add acrylated hyperbranched polyester amide.

[0062] Compared with Example 1 and Comparative Example 2, the wear amount of Example 1 is less than that of Comparative Example 2. The mass loss rate of Example 1 after soaking in water, alcohol and grease is less than that of Comparative Example 2 after soaking in water, alcohol and grease. The number of folds in Example 1 is greater than that in Comparative Example 2. The adhesion level of Example 1 is lower than that of Comparative Example 2.

[0063] The difference between Example 1 and Comparative Example 2 is that: Example 1 adds liquid crystal diacrylate; liquid crystal diacrylate contains rigid mesocrystalline units and terminal acrylate groups. When uncured, the molecules are oriented. When UV cured, the volume shrinkage is low, the internal stress is small, and it is not easy to fall off. After polymerization, it forms an ordered, tight, rigid chain, which reduces the free volume, hinders the diffusion of substances, and can also effectively disperse stress and improve the hardness of the ink layer; therefore, it is necessary to add liquid crystal diacrylate.

[0064] Comparing Examples 1 and Examples 4-9, the wear amount of Example 1 is less than that of Examples 4-9. The mass loss rate of Example 1 after soaking in water, alcohol and grease is less than that of Examples 4-9 after soaking in water, alcohol and grease. The number of folds in Example 1 is greater than that in Examples 4-9. The adhesion level of Example 1 is lower than that of Examples 4-9.

[0065] The difference between Example 1 and Examples 4-9 is that the photoinitiators in Example 1 are photoinitiator TPO-L and photoinitiator 819. Photoinitiator TPO-L is suitable for surface curing, while photoinitiator 819 is beneficial for deep curing. The combination of the two allows the ink to cure evenly from the surface to the interior, reducing the curing gradient and the residue of unreacted monomers, giving the product characteristics of low migration, low odor, wear resistance and non-detachment. Therefore, using photoinitiator TPO-L and photoinitiator 819 as photoinitiators is superior.

[0066] Comparing Examples 1 and 10-13, the wear amount of Example 1 is less than that of Examples 10-13. The mass loss rate of Example 1 after soaking in water, alcohol, and grease is less than that of Examples 10-13 after soaking in water, alcohol, and grease. The number of folds in Example 1 is greater than that in Examples 10-13. The adhesion grade of Example 1 is lower than that in Examples 10-13. The wear amount of Examples 10-11 is less than that of Examples 12-13. The mass loss rate of Examples 10-11 after soaking in water, alcohol, and grease is less than that of Examples 12-13 after soaking in water, alcohol, and grease. The number of folds in Example 10-11 is greater than that in Examples 12-13. The adhesion grade of Example 10-11 is lower than that in Examples 12-13.

[0067] The difference between Examples 1, 10-11 and Examples 12-13 is that the mass ratio of photoinitiator TPO-L to photoinitiator 819 in Examples 1, 10-11 is (1-2):1. This ratio avoids excessively rapid surface curing leading to oxygen inhibition or insufficient deep curing, allowing photoinitiator TPO-L and photoinitiator 819 to better exert their synergistic effect. Therefore, a mass ratio of photoinitiator TPO-L to photoinitiator 819 of (1-2):1 is preferred.

[0068] Comparing Examples 1 and 14-16, the wear amount of Example 1 is close to that of Examples 14-16. The mass loss rate of Example 1 after soaking in water, alcohol and grease is close to that of Examples 14-16 after soaking in water, alcohol and grease. The number of folds in Example 1 is close to that in Examples 14-16. The adhesion level of Example 1 is the same as that of Examples 14-16.

[0069] The pigments in Examples 1 and 14-16 were selected from Pigment Blue 15:1, Pigment Red 57:1, Pigment Yellow 14, and Pigment Orange 64. These pigments are all stabilized organic pigments with compact molecular structures and moderate polarity. They have good compatibility with acrylic resins and are not easily migrated in the system. The wide variety of raw materials makes them more suitable for various color requirements and expands the application scope. Therefore, selecting Pigment Blue 15:1, Pigment Red 57:1, Pigment Yellow 14, and Pigment Orange 64 is preferable.

[0070] Comparing Examples 1 and 17-19, the wear amount of Examples 1 and 19 is less than that of Examples 17-18. The mass loss rate of Examples 1 and 19 after soaking in water, alcohol, and grease is less than that of Examples 17-18 after soaking in water, alcohol, and grease. The number of folds in Examples 1 and 19 is greater than that in Examples 17-18. The adhesion grade of Examples 1 and 19 is lower than that in Examples 17-18. The wear amount of Example 18 is less than that of Example 17. The mass loss rate of Example 18 after soaking in water, alcohol, and grease is less than that in Example 17 after soaking in water, alcohol, and grease. The number of folds in Example 18 is greater than that in Example 17. The adhesion grade of Example 18 is lower than that of Example 17.

[0071] The difference between Example 1 and Examples 17-19 is that the talc powder in Examples 1 and 18-19 was modified with a silane coupling agent, and the talc powder in Examples 1 and 19 was modified with a silane coupling agent containing acryloyloxy groups. Modification of the talc powder with a silane coupling agent containing acryloyloxy groups enhances the interfacial bonding between the filler and the resin, reduces interfacial defects and micropores, thereby improving wear resistance and adhesion. Furthermore, when γ-methacryloyloxypropyltrimethoxysilane is used as the coupling agent, the methacryloyloxy group exhibits strong copolymerization with the acrylate system, and after hydrolysis of the methoxy group, it firmly bonds to the surface of the talc powder, resulting in more uniform dispersion of the talc powder. Therefore, modification of the talc powder with a silane coupling agent is preferable, and using a silane coupling agent containing acryloyloxy groups is preferred.

[0072] Comparing Example 1 and Example 20, the wear amount of Example 1 is less than that of Example 20. The mass loss rate of Example 1 after soaking in water, alcohol and grease is less than that of Example 20 after soaking in water, alcohol and grease. The number of folds in Example 1 is greater than that in Example 20. The adhesion level of Example 1 is lower than that of Example 20.

[0073] The difference between Example 1 and Example 20 is that the ink in Example 1 also contains polyether-modified polysiloxane; polyether-modified polysiloxane can reduce the surface tension of the ink, improve leveling and defoaming ability, make the coating more uniform and dense, provide additional lubrication, improve wear resistance, and its low volatility helps to reduce odor; therefore, adding polyether-modified polysiloxane to the ink is superior.

[0074] Comparing Examples 1 and 21-22, the wear amount of Example 1 is less than that of Example 21-22. The mass loss rate of Example 1 after soaking in water, alcohol and grease is less than that of Example 21-22 after soaking in water, alcohol and grease. The number of folds in Example 1 is greater than that in Example 21-22. The adhesion level of Example 1 is lower than that of Example 21-22.

[0075] The difference between Example 1 and Examples 21-22 is that the mass ratio of epoxy acrylate, silicone acrylate, acrylated hyperbranched polyesteramide, modified talc, pigment blue 15:1, ethoxylated trimethylolpropane triacrylate, photoinitiator TPO-L, photoinitiator 819, liquid crystal diacrylate, and polyether-modified polysiloxane in the ink of Example 1 is 35:5:10:4:30:35:6:4:12:0.5. Therefore, the mass ratio of epoxy acrylate, silicone acrylate, acrylated hyperbranched polyesteramide, modified talc, pigment blue 15:1, ethoxylated trimethylolpropane triacrylate, photoinitiator TPO-L, photoinitiator 819, liquid crystal diacrylate, and polyether-modified polysiloxane in the ink of 35:5:10:4:30:35:6:4:12:0.5 is preferred.

[0076] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of protection claimed by the present invention, they are protected by patent law.

Claims

1. A low-migration, low-odor UV-curable flexographic ink, characterized in that, Includes the following components in parts by weight: 20-50 parts of epoxy acrylate, 3-8 parts of organosilicon acrylate, Acrylate-esterified hyperbranched polyesteramide, 5-15 parts, 10-15 parts of liquid crystal diacrylate, 20-50 parts of photocurable monomer, 5-15 parts of photoinitiator 15-45 parts pigment 1-8 parts talcum powder; The photocurable monomer is any one of ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate. The photoinitiator is one or more of the following: photoinitiator TPO-L, photoinitiator 819, and photoinitiator 184.

2. The low-migration, low-odor UV-curable flexographic ink according to claim 1, characterized in that, The photoinitiators are photoinitiator TPO-L and photoinitiator 819.

3. The low-migration, low-odor UV-curable flexographic ink according to claim 2, characterized in that, The mass ratio of the photoinitiator TPO-L to the photoinitiator 819 is (1~2):

1.

4. The low-migration, low-odor UV-curable flexographic ink according to claim 1, characterized in that, The pigment is any one of pigment blue 15:1, pigment red 57:1, pigment yellow 14, and pigment orange 64.

5. The low-migration, low-odor UV-curable flexographic ink according to claim 1, characterized in that, The talc powder was modified with a silane coupling agent containing acryloyloxy group.

6. The low-migration, low-odor UV-curable flexographic ink according to claim 5, characterized in that, The silane coupling agent containing acryloyloxy group is γ-methacryloyloxypropyltrimethoxysilane.

7. The low-migration, low-odor UV-curable flexographic ink according to claim 1, characterized in that, The component also contains 0.2 to 1 part of polyether-modified polysiloxane.

8. A method for preparing a low-migration, low-odor UV-curable flexographic ink as described in claims 1-7, characterized in that, Includes the following steps: S1: Epoxy acrylate, silicone acrylate, acrylated hyperbranched polyester amide, talc and pigment are first premixed and then dispersed to obtain a dispersion slurry; S2: The dispersion slurry is milled, and then all components except epoxy acrylate, silicone acrylate, acrylated hyperbranched polyester amide, talc and pigment are added. After stirring and mixing, the ink is obtained.

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