A light / heat dual-curable bio-based UV ink composition and a method for preparing the same

Abstract

This invention discloses a photo / thermal dual-curing bio-based UV ink composition and its preparation method, relating to the field of UV-curable printing materials. It comprises the following raw materials in parts by weight: 100 parts of polypropylene carbonate diol-type polyurethane acrylate oligomer, 5-20 parts of a thermosetting component, 50-150 parts of an reactive diluent, 2-10 parts of a free radical photoinitiator, 0-80 parts of a colorant, and 0-10 parts of other additives; the thermosetting component includes eugenol-furfurylamine type benzoxazine monomer. The UV ink composition obtained by this invention can be heat-treated after photocuring. The polybenzoxazine network is interpenetrated after the formed polyurethane acrylate pre-crosslinked network, forming an interpenetrating or interpenetrating polymer network, and additional crosslinking can occur. This not only improves the strength and flexibility of the ink layer but also effectively enhances solvent resistance and adhesion, resulting in a UV ink composition with excellent overall performance.

Description

Technical Field

[0001] This invention relates to the field of UV-curable printing materials, and in particular to a photo / thermal dual-curing bio-based UV ink composition and its preparation method. Background Technology

[0002] UV ink, also known as ultraviolet ink, can be cured into a film by a photochemical reaction caused by ultraviolet light of a certain wavelength, which polymerizes the prepolymers and monomers in the ink. UV ink has advantages such as being solvent-free, safe and reliable, low in VOCs, good printability, high quality, and high production efficiency due to its instant curing, and is widely used in high-speed printing and other fields.

[0003] UV inks generally use unsaturated acrylate materials. Among them, polyurethane acrylate (PUA) system combines the advantages of polyurethane resin and acrylate resin, and has solvent resistance, low temperature resistance, abrasion resistance, thermal shock resistance and good adhesion. It is the core film-forming resin of UV inks and determines the various properties of UV inks.

[0004] Traditional polyurethane acrylates typically employ flexible oligomeric polyols, such as polyether polyols or polyester polyols, to form the soft segments, while rigid isocyanates and small-molecule chain extenders form the hard segments. However, while polyether-type polyurethane acrylates exhibit good hydrolysis resistance, they suffer from a poor balance between flexibility and mechanical strength. Polyester-type polyurethane acrylates possess high mechanical strength, but their ester bonds are prone to hydrolysis, causing the cured ink layer to degrade rapidly in humid and hot environments. This makes them unsuitable for meeting the stringent requirements of UV inks used in food processing and medical sterilization. Furthermore, traditional polyurethane acrylates are heavily reliant on fossil resources, failing to meet current demands for sustainable development.

[0005] Currently, a polypropylene carbonate polyol copolymerized from carbon dioxide and propylene oxide as main raw materials has a molecular structure between polyester polyols and polyether polyols, exhibiting excellent comprehensive properties. Chinese patent application CN108948321A, entitled "A UV-curable waterborne polyurethane acrylate and its preparation method and application," describes a polyurethane using polypropylene carbonate diol as a raw material. However, this method requires the introduction of a hydrophilic chain extender, employs an emulsification method, and results in a waterborne dispersion of polyurethane resin, which cannot be directly used in solvent-free UV inks with 100% solids content.

[0006] Furthermore, traditional UV inks undergo significant volume shrinkage during the curing process, leading to a decrease in the interfacial adhesion between the ink layer and the substrate. Instant curing also prevents the ink from wetting and spreading sufficiently on the substrate surface, weakening the physical anchoring effect and hindering deep curing, thus affecting the protective performance of the ink layer. Conventional UV inks are also limited by photoinitiator efficiency and double bond conversion rate, resulting in poor solvent resistance and making printed images or films prone to blurring or damage.

[0007] Therefore, obtaining a UV ink that has excellent overall performance, is environmentally friendly, and can significantly improve the solvent resistance, adhesion, and aging resistance of UV inks is of great significance for expanding the application range of UV inks. Summary of the Invention

[0008] The purpose of this invention is to provide a photo / thermal dual-curing bio-based UV ink composition and its preparation method, so as to solve the technical problems of conventional UV ink compositions in the prior art, such as difficulty in balancing flexibility and hydrolysis resistance, poor solvent wiping resistance and adhesion.

[0009] The technical problem to be solved by this invention can be achieved through the following technical solution: In a first aspect, the present invention provides a photo / thermal dual-curing bio-based UV ink composition, comprising the following raw materials in parts by weight: 100 parts of polypropylene carbonate diol-type polyurethane acrylate oligomer; 5-20 parts of thermosetting component; 50-150 parts of reactive diluent; 2-10 parts of free radical photoinitiator; Colorant 0-80 parts; Other adjuvants: 0-10 parts; The thermosetting component includes eugenol-furfurylamine type benzoxazine monomer.

[0010] Preferably, other additives include defoamers and leveling agents.

[0011] By adopting the above technical solution, the UV ink composition of the present invention introduces polypropylene carbonate diol-type polyurethane acrylate oligomers, which contain carbonate bonds with high rotational freedom, giving the polyurethane acrylate network formed after ink curing intrinsic flexibility. The thermosetting component, eugenol-furfurylamine-type benzoxazine monomer, exists in a latent state before thermosetting, and does not interfere with the flexibility of the initial network formed during UV curing of the polyurethane acrylate. After complete curing, the eugenol-furfurylamine-type benzoxazine monomer forms a highly hydrophobic crosslinked structure, effectively preventing water molecules from diffusing into the polyurethane acrylate network, thereby synergistically improving the hydrolysis resistance of the ink layer. Therefore, the obtained UV ink composition can maintain excellent flexibility and hydrolysis resistance.

[0012] This invention also introduces eugenol-furfurylamine type benzoxazine monomers to obtain a UV ink composition with post-processing heat-enhancing function. This allows the UV ink composition to achieve a secondary performance improvement through heat treatment after photocuring, transforming potential thermal damage during the process into thermal strengthening. The eugenol-furfurylamine type benzoxazine monomer itself has good compatibility with the polypropylene carbonate diol type polyurethane acrylate oligomer system. Its phenolic hydroxyl structure and tertiary amine groups can form strong hydrogen bond interactions with the polyurethane acrylate oligomers, thereby ensuring the system's density.

[0013] More importantly, the introduction of eugenol-furfurylamine type benzoxazine monomers will form interpenetrating or intertwined polymer network structures with polypropylene carbonate diol type polyurethane acrylate oligomers during the curing process. Specifically, under photocuring, the polypropylene carbonate diol type polyurethane acrylate oligomers first form a slightly cross-linked network. Then, through heat treatment, the eugenol-furfurylamine type benzoxazine monomers undergo ring-opening and polycondensation. The resulting polybenzoxazine network will interpenetrate and entangle with the previously existing slightly cross-linked network to form an interpenetrating polymer network, thereby greatly improving the synergistic mechanical properties of the ink layer.

[0014] Furthermore, due to the interpenetrating structure of the polybenzoxazine network in the polyurethane acrylate crosslinking network, the volume shrinkage caused by photocuring can be greatly reduced, thus improving the adhesion of the ink layer. In addition, the polybenzoxazine network has a high aromatic ring density and strong hydrogen bond crosslinking, making it difficult for solvent molecules to penetrate and swell its crosslinking structure. The structure of the interpenetrating network also makes the crosslinking points of the two polymer networks complementary, greatly improving the solvent resistance of the ink.

[0015] Preferably, the raw material for the polypropylene carbonate diol-type polyurethane acrylate oligomer includes polypropylene carbonate diol; polypropylene carbonate diol is a copolymer of carbon dioxide and propylene oxide, with a number average molecular weight of 1500-2500 g / mol and a bio-based carbon content of 25-80%.

[0016] More preferably, polypropylene carbonate diol is prepared by the following method: A molecular weight regulator and a metal coordination catalyst are added to propylene oxide, mixed evenly, and the air is removed. The temperature is raised to 60-80°C, carbon dioxide is introduced, and the system pressure is maintained at 4-6 MPa. After reacting at a constant temperature for 4-6 hours, the water is removed under vacuum to obtain polypropylene carbonate diol.

[0017] More preferably, the molecular weight regulator includes one or more combinations of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, succinic anhydride, phthalic anhydride, maleic anhydride, and hexahydrophthalic anhydride.

[0018] More preferably, the metal coordination catalyst includes one or more combinations of zinc glutarate, bimetallic cyanide, Salen Co complex, and porphyrin-type metal complex.

[0019] Preferably, the polypropylene carbonate diol-type polyurethane acrylate oligomer is prepared according to the following method: S1. After dehydration treatment, polypropylene carbonate diol is added to diisocyanate and catalyst at 60-65°C, mixed, and then the temperature is raised to 80-85°C and stirred for 2-4 hours to obtain isocyanate-terminated polyurethane prepolymer. S2. Lower the temperature to 50-60℃, add hydroxy acrylate and polymerization inhibitor, mix, then raise the temperature to 70-75℃ and stir for 4-5 hours to obtain the final product.

[0020] Preferably, the diisocyanate includes one or more combinations of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate and hexamethylene diisocyanate; the hydroxy acrylate includes one or a combination of hydroxyethyl acrylate and hydroxypropyl acrylate.

[0021] Preferably, the molar ratio of diisocyanate to polypropylene carbonate diol is (1.6-1.9):1; and the molar ratio of isocyanate groups to hydroxyl groups in the raw materials of polypropylene carbonate diol-type polyurethane acrylate oligomers is (0.96-1.04):1.

[0022] More preferably, the catalyst includes one or more of dibutyltin dilaurate and stannous octoate.

[0023] More preferably, the polymerization inhibitor includes one or more combinations of p-hydroxyanisole, hydroquinone, and 2,6-di-tert-butyl-p-cresol.

[0024] By adopting the above technical solution, the raw material of the polypropylene carbonate diol type polyurethane acrylate oligomer of the present invention includes polypropylene carbonate diol, with carbon dioxide as the main raw material, which can fix carbon dioxide and is a biomass-based material that is green and environmentally friendly.

[0025] During the preparation process, under the action of a catalyst, the hydroxyl groups contained in polypropylene carbonate diol undergo an affinity addition reaction with the isocyanate groups in diisocyanate to form a linear polyurethane prepolymer with terminal isocyanate groups. Then, hydroxy acrylate is added, and the hydroxyl groups contained therein can further undergo an addition reaction with the terminal isocyanate groups. A polymerization inhibitor is added to suppress the free radical polymerization of the double bonds of hydroxy acrylate during heating, ensuring that polyurethane acrylate oligomers are obtained.

[0026] Furthermore, this preparation method ensures the production of solvent-free and anhydrous polyurethane acrylates, without the introduction of emulsifiers and water. It is not only compatible with 100% solid content UV inks, but also reduces the use of co-solvents and lowers VOC emissions. The resulting oligomers have stable structures and can be directly used in UV inks and photocuring. It also ensures molecular-level compatibility with eugenol-furfurylamine type benzoxazine monomers, providing a prerequisite for subsequent interpenetrating or intercalating polymer networks.

[0027] In the preparation process of this invention, by precisely controlling the molecular weight of polypropylene carbonate diol, which is also the molecular weight of the soft segment of polyurethane acrylate, the resulting polyurethane acrylate can achieve high flexibility while avoiding chain entanglement caused by high molecular weight. This ensures the linear structure of the oligomer, reduces the formation of branched or cross-linked structures, and thus significantly reduces the viscosity of the oligomer, making it suitable for the printability requirements of UV ink compositions. Furthermore, using polypropylene carbonate diol as the soft segment unit achieves an effective balance between hydrolysis resistance and flexibility. Its low viscosity also facilitates the wetting of the substrate by the UV ink composition before curing, and, synergistically with the chemical bonding of polyurethane acrylate, further enhances the adhesion between the ink and the substrate.

[0028] Preferably, the raw materials for the eugenol-furfurylamine type benzoxazine monomer include eugenol, furfurylamine, and paraformaldehyde in a molar ratio of (0.45-0.55):(0.45-0.55):1.

[0029] Preferably, the eugenol-furfurylamine type benzoxazine monomer is prepared according to the following method: Eugenol and furfural are added to paraformaldehyde, and the mixture is stirred at 100-120°C for 1.5-3 hours. Finally, the mixture is washed, dried, filtered, and rotary evaporated to obtain the final product.

[0030] By adopting the above technical solution, paraformaldehyde will depolymerize at high temperature to form formaldehyde molecules. The carbonyl carbon of formaldehyde is attacked by the nucleophilic pair electrons on the nitrogen atom of furfurylamine to form a hydroxymethyl intermediate, which then reacts further to form a stable dihydroxymethylamine. The dihydroxymethylamine further undergoes an electrophilic substitution reaction with the phenolic hydroxyl group of eugenol. Finally, the oxygen atom on the phenolic hydroxyl group and the hydroxymethyl group on the side chain undergo intramolecular condensation to form a eugenol-furfurylamine type benzoxazine monomer with a six-membered oxazine heterocyclic structure.

[0031] Common benzoxazine compounds undergo ring-opening polymerization via a cationic mechanism, requiring heterolytic cleavage of the CO bonds in the oxazine ring to generate cationic active centers, thus initiating polymerization. This process demands high thermal energy and long holding times for effective cleavage and high conversion rates. Furthermore, the crosslinking density formed after polymerization is limited, often requiring large additions to achieve good reinforcing effects. However, benzoxazine itself has poor compatibility with the polymer matrix, failing to form an effective interpenetrating network. Directly introducing it into UV inks is incompatible with the UV ink curing process, requiring prolonged high-temperature baking during curing. This not only damages the substrate but may also cause the ink layer to become brittle due to high addition levels, affecting performance.

[0032] The eugenol-furfurylamine type benzoxazine monomer obtained in this invention, as a benzoxazine derivative, possesses the thermosetting properties of benzoxazine. Furthermore, the furan ring and allyl groups introduced into eugenol and furfurylamine significantly reduce the activation energy for ring-opening polymerization of benzoxazine, accelerating the polymerization rate and achieving high conversion rates at lower temperatures and in shorter times. Moreover, the polybenzoxazine network formed after ring-opening polymerization of the eugenol-furfurylamine type benzoxazine monomer exhibits high crosslinking density, providing excellent reinforcing effects even at low addition levels.

[0033] Furthermore, eugenol-furfurylamine type benzoxazine monomers and polypropylene carbonate diol type polyurethane acrylate oligomers have good compatibility. During thermosetting, they can undergo in-situ ring-opening polymerization inside the photocurable network to form interpenetrating or interwoven polymer networks. The two phases interpenetrate each other, reducing phase separation and thus enhancing the mechanical strength of the ink layer.

[0034] Furthermore, the allyl and furanyl groups contained in the eugenol-furfurylamine type benzoxazine monomer can form hydrogen bonds with the carbonate bonds in the polypropylene carbonate diol type polyurethane acrylate oligomer at high temperatures, resulting in additional crosslinking and promoting compatibility between the two phases. Moreover, the synergistic effect of its dual crosslinking and hydrogen bonding can significantly enhance the reinforcing effect, resulting in a UV ink composition that effectively balances flexibility and strength.

[0035] Meanwhile, the eugenol-furfurylamine type benzoxazine monomer does not contain chromophores that can be excited by ultraviolet light, thus it does not undergo ring-opening polymerization under 65-405nm UV irradiation, ensuring that it exists only as a "latent" component during the UV curing stage. The eugenol-furfurylamine type benzoxazine monomer of the present invention overcomes the shortcomings of traditional benzoxazines that require high temperature, long time and high content, and can further significantly improve the mechanical strength, solvent resistance and compatibility of the ink layer.

[0036] Preferably, the reactive diluent comprises ethoxyethoxyethyl acrylate and 1,6-hexanediol diacrylate in a mass ratio of (1-3):1.

[0037] By adopting the above technical solution, this invention selects a compound composition of ethoxyethoxyethyl acrylate and 1,6-hexanediol diacrylate as an reactive diluent. This composition can reduce overall viscosity, improve flexibility and adhesion, introduce multifunctional groups, increase overall crosslinking density, accelerate photocuring speed, and improve solvent resistance and strength. Furthermore, it exhibits good compatibility with eugenol-furfurylamine type benzoxazine monomers, preventing phase separation.

[0038] Preferably, the curing method for the UV ink composition is a dual curing method, specifically including the following steps: First curing: The UV ink composition is coated onto the surface of the substrate and then irradiated with UV light to form a pre-cured coating, thus obtaining a pre-treated substrate; Second curing: Place the pretreated substrate at 100-150℃ for 5-30 minutes to cure completely.

[0039] More preferably, the heat treatment method includes any one of the following: residual heat treatment in post-printing processing, heat treatment in a dedicated oven, hot air heating treatment, and infrared heating treatment.

[0040] More preferably, the UV ink composition can be used in any of the following: food flexible packaging printing, medical packaging printing, printed electronics, smart labels, and biodegradable substrate printing.

[0041] By adopting the above technical solution, in the first curing process, the free radical photoinitiator absorbs ultraviolet light energy to generate free radicals, which then attack the acrylate double bonds of the polypropylene carbonate diol-type polyurethane acrylate oligomer, initiating pre-crosslinking and forming a pre-crosslinked polyurethane acrylate crosslinked network. At this time, the eugenol-furfurylamine-type benzoxazine monomer is uniformly distributed in the pre-crosslinked network in a molecular-level dispersion state. Then, the temperature is increased, and the eugenol-furfurylamine-type benzoxazine monomer undergoes ring-opening polymerization. The polybenzoxazine network generated by thermal polymerization interpenetrates and entangles with the pre-crosslinked network, thereby forming an interpenetrating or interwoven polymer network.

[0042] The ink layer formed by the above curing method has a high cross-linking density, which can significantly improve the modulus, hardness and solvent penetration resistance of the ink layer. Moreover, the polybenzoxazine network contained therein has a high aromatic ring density and strong hydrogen bond cross-linking, making it difficult for solvent molecules to swell or penetrate the network, thereby improving the solvent wiping resistance of the ink layer, improving the adhesion and heat resistance of the ink layer, and making it suitable for a variety of substrates to achieve deep curing.

[0043] Secondly, the present invention provides a method for preparing a photo / thermal dual-curing bio-based UV ink composition, which includes the following process steps: Mix all raw materials under light-protected conditions, stir at 500–1500 rpm for 20–60 minutes, and finally filter to obtain the final product.

[0044] The beneficial effects of this invention are: 1. The photo / thermal dual-curing bio-based UV ink composition provided by the present invention contains polypropylene carbonate diol-type polyurethane acrylate oligomers. By precisely controlling the molecular weight of the soft segment raw material polypropylene carbonate diol and the preparation process, the obtained polypropylene carbonate diol-type polyurethane acrylate oligomers can have both low viscosity and high flexibility, and are solvent-free and anhydrous, which can be adapted to 100% solid content UV inks and meet the requirements of ink printability.

[0045] 2. The photo / thermal dual-curing bio-based UV ink composition provided by the present invention also contains a thermosetting component, which includes eugenol-furfurylamine type benzoxazine monomer. This can overcome the defects of traditional benzoxazine, which must be used at high temperature, for a long time and in high content. It also has good compatibility with polypropylene carbonate diol type polyurethane acrylate oligomer system.

[0046] 3. The photo / thermal dual-curing bio-based UV ink composition provided by this invention employs dual curing during curing, performing photocuring followed by heat treatment. This allows for the interpenetration of a polybenzoxazine network after the formation of a polyurethane acrylate pre-crosslinked network, and also enables additional crosslinking. This synergistic effect not only improves the strength and flexibility of the ink layer but also effectively enhances solvent resistance and adhesion, resulting in a UV ink composition with excellent overall performance. Furthermore, both phases are derived from biomass substrates, making it green and environmentally friendly. Detailed Implementation

[0047] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0048] Preparation Example Preparation Example 1: A polypropylene carbonate diol was prepared according to the following method: 60g of ethylene glycol and 0.8g of bimetallic cyanide DMC catalyst were added to 600g of propylene oxide. After mixing thoroughly and removing air, the temperature was raised to 70℃, carbon dioxide was introduced, and the system pressure was maintained at 5MPa. After reacting at a constant temperature for 5h, the mixture was vacuum dehydrated at 70℃ for 60min to obtain polypropylene carbonate diol. The hydroxyl value of the obtained polypropylene carbonate diol was 56mgKOH / g, the average number-average molecular weight was 2000g / mol, and the bio-based carbon content was 30%.

[0049] Preparation Example 2: A polypropylene carbonate diol-type polyurethane acrylate oligomer was prepared according to the following method: S1. Take 150g of the polypropylene carbonate diol prepared in Example 1, and vacuum dehydrate it for 2h at 110℃ and -0.095MPa. Then add 28.3g of isophorone diisocyanate and 0.1g of dibutyltin dilaurate at 65℃, mix, raise the temperature to 80℃, and stir for 3h to obtain isocyanate-terminated polyurethane prepolymer with an NCO% of 4.2%. S2. Lower the temperature to 60℃, add 17.4g of hydroxyethyl acrylate and 0.1g of p-hydroxyanisole, mix, raise the temperature to 70℃, and stir for 4 hours to obtain the polypropylene carbonate diol type polyurethane acrylate oligomer with an average number average molecular weight of 5600g / mol, a melt viscosity of 4600mPa·s at 60℃, and a functionality of 2.

[0050] Preparation Example 3: A eugenol-furfurylamine type benzoxazine monomer was prepared according to the following method: Add 16.4g of eugenol and 9.7g of furfural to 6.0g of paraformaldehyde, stir and react at 110℃ for 2h. Finally, dissolve in 50mL of dichloromethane, wash three times with 1mol / L sodium hydroxide aqueous solution and once with deionized water, collect the organic phase, add anhydrous sodium sulfate for drying, filter to remove anhydrous sodium sulfate, and remove the solvent by rotary evaporation at 40℃ to obtain the final product.

[0051] Example Example 1: A photo / thermal dual-curing bio-based UV ink composition was prepared according to the following method: Take 100 parts of the polypropylene carbonate diol type polyurethane acrylate oligomer prepared in Preparation Example 2, 5 parts of the eugenol-furfurylamine type benzoxazine monomer prepared in Preparation Example 3, 95 parts of reactive diluent, 5 parts of free radical photoinitiator and 0.5 parts of other additives, and mix them under light-protected conditions. The reactive diluent includes 65 parts of ethoxyethoxyethyl acrylate and 30 parts of 1,6-hexanediol diacrylate. The free radical photoinitiator includes 3 parts of photoinitiator TPO and 2 parts of photoinitiator 184. The other additive is water-based leveling agent BYK-333. Stir at 1000 rpm for 40 min and finally filter to obtain the final product.

[0052] Examples 2 to 4 describe a photo / thermal dual-curing bio-based UV ink composition, differing from Example 1 only in the adjustment of the raw material ratios, as shown in Table 1: Table 1. Raw material formulas for Examples 1 to 4

[0053] Comparative Example Comparative Example 1 is a photo / thermal dual-curing bio-based UV ink composition, which differs from Example 3 only in that the eugenol-furfurylamine type benzoxazine monomer prepared in Preparation Example 3 is not added.

[0054] Comparative Example 2, a photo / thermal dual-curing bio-based UV ink composition, differs from Example 3 only in that the amount of eugenol-furfurylamine type benzoxazine monomer added in Preparation Example 3 is 25 parts.

[0055] Comparative Example 3 is a photo / thermal dual-curing bio-based UV ink composition, which differs from Example 3 only in that an equal amount of polyester polyurethane acrylate is used to replace the polypropylene carbonate diol polyurethane acrylate oligomer obtained in Preparation Example 2.

[0056] Comparative Example 4, a photo / thermal dual-curing bio-based UV ink composition, differs from Example 3 only in that an equal amount of polyether-type polyurethane acrylate is used to replace the polypropylene carbonate diol-type polyurethane acrylate oligomer obtained in Preparation Example 2.

[0057] Comparative Example 5 is a photo / thermal dual-curing bio-based UV ink composition, which differs from Comparative Example 1 only in that an equal amount of polyester-type polyurethane acrylate is used to replace the polypropylene carbonate diol-type polyurethane acrylate oligomer obtained in Preparation Example 2.

[0058] Comparative Example 6 is a photo / thermal dual-curing bio-based UV ink composition, which differs from Comparative Example 1 only in that an equal amount of polyether-type polyurethane acrylate is used to replace the polypropylene carbonate diol-type polyurethane acrylate oligomer obtained in Preparation Example 2.

[0059] Performance testing methods 1. UV Curing Speed ​​Test: The UV ink compositions obtained in the examples and comparative examples were coated on the surface of a PET film with a wet thickness of 12 μm, and then cured under a 120 W / cm mercury lamp at a speed of 80–100 m / min. The surface dryness was measured using a UV energy meter. The test results are shown in Table 2. Table 2 Results of UV Curing Speed ​​Test

[0060] Example 3 underwent a secondary curing treatment. The photocured sample of Example 3 was heat-treated at 120°C. The number of ethanol wipes on the sample was tested at different heat treatment times, and the improvement rate of solvent resistance compared to the photocured sample of Example 3 was calculated. The test results are shown in Table 3. Table 3 Results of changes in ethanol wiping resistance after heat treatment in Example 3

[0061] According to Tables 2 and 3, it can be seen that the photo / thermal dual-curing bio-based UV ink composition provided in the embodiments of the present invention has a fast curing speed, and the solvent resistance of the ink layer is significantly improved after secondary thermal curing.

[0062] 2. Ink layer performance testing: The UV ink compositions obtained in the examples and comparative examples were subjected to dual photo / thermal curing treatment. Specifically: First curing: The UV ink composition is coated onto the surface of the substrate (PET film), and a pre-cured coating is formed by UV irradiation to obtain the pre-treated substrate; Second curing: The pretreated substrate is heat-treated at 125°C for 30 minutes to obtain the ink layer sample after complete curing.

[0063] (1) Adhesion performance test: The adhesion of the ink layer samples obtained in the examples and comparative examples was tested according to the relevant records in GB / T 9286-2021 "Paints and Varnishes Cross-cut Test". (2) Solvent resistance test: According to the relevant records in ASTM D5402-19 (2024) "Evaluation of solvent resistance of organic coatings by wiping with solvent", ethanol was selected as the solvent to test the solvent resistance of the ink layers obtained in the examples and comparative examples. Specifically, the number of times the solvent resistance was wiped was tested after the first curing and the second curing. (3) Weather resistance test: The weather resistance of the ink layer of the example and the comparative example was tested using QUV accelerated aging test. The test time was 1000h, and the yellowing ΔE value (color change) before and after aging was tested. (4) Moist heat aging test: According to the relevant records in GB / T 14522-2008 "Artificial climate aging test method for plastics, coatings and rubber materials for mechanical industry products: fluorescent ultraviolet lamp", the moisture heat aging resistance of the ink layer samples obtained in the examples and comparative examples was tested, and the gloss retention rate of the samples before and after the test was tested.

[0064] The results of the above experiments are shown in Table 4: Table 4. Test Results of Ink Layer Performance

[0065] As shown in Table 4, the UV ink composition with added eugenol-furfurylamine benzoxazine monomers exhibits significantly improved adhesion and solvent resistance. Furthermore, the addition of eugenol-furfurylamine benzoxazine monomers enhances the gloss retention and weather resistance of the UV ink composition. Compared to polyester-type and polyether-type polyurethane acrylates, the polypropylene carbonate diol-type polyurethane acrylate oligomers provided by this invention demonstrate better performance enhancement due to the eugenol-furfurylamine benzoxazine monomers. This may be because the eugenol-furfurylamine benzoxazine monomers and polypropylene carbonate diol-type polyurethane acrylate oligomers form interpenetrating or interwoven network structures during the curing process, resulting in additional crosslinking. This not only improves solvent resistance but also enhances the weather resistance of the ink, increasing the strength of the formed ink layer and improving the ethanol wiping resistance by ≥70%.

[0066] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A photo / thermal dual-curing bio-based UV ink composition, characterized in that, The raw materials include the following parts by weight: 100 parts of polypropylene carbonate diol-type polyurethane acrylate oligomer; 5-20 parts of thermosetting component; 50-150 parts of reactive diluent; 2-10 parts of free radical photoinitiator; Colorant 0-80 parts; Other adjuvants: 0-10 parts; The thermosetting component includes eugenol-furfurylamine type benzoxazine monomer.

2. The photo / thermal dual-curing bio-based UV ink composition according to claim 1, characterized in that, The raw material for the polypropylene carbonate diol-type polyurethane acrylate oligomer includes polypropylene carbonate diol; the polypropylene carbonate diol is a copolymer of carbon dioxide and propylene oxide, with a number average molecular weight of 1500-2500 g / mol and a bio-based carbon content of 25-80%.

3. The photo / thermal dual-curing bio-based UV ink composition according to claim 2, characterized in that, The polypropylene carbonate diol-type polyurethane acrylate oligomer was prepared according to the following method: S1. After dehydration treatment, polypropylene carbonate diol is added to diisocyanate and catalyst at 60-65°C, mixed, and then the temperature is raised to 80-85°C and stirred for 2-4 hours to obtain isocyanate-terminated polyurethane prepolymer. S2. Lower the temperature to 50-60℃, add hydroxy acrylate and polymerization inhibitor, mix, then raise the temperature to 70-75℃ and stir for 4-5 hours to obtain the final product.

4. The photo / thermal dual-curing bio-based UV ink composition according to claim 3, characterized in that, The diisocyanate includes one or more combinations of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate; the hydroxy acrylate includes one or a combination of hydroxyethyl acrylate and hydroxypropyl acrylate.

5. The photo / thermal dual-curing bio-based UV ink composition according to claim 3, characterized in that, The molar ratio of the diisocyanate to polypropylene carbonate diol is (1.6-1.9):1; the molar ratio of isocyanate groups to hydroxyl groups in the raw materials of the polypropylene carbonate diol-type polyurethane acrylate oligomer is (0.96-1.04):

1.

6. The photo / thermal dual-curing bio-based UV ink composition according to claim 1, characterized in that, The raw materials for the eugenol-furfurylamine type benzoxazine monomer include eugenol, furfurylamine, and paraformaldehyde in a molar ratio of (0.45-0.55):(0.45-0.55):

1.

7. The photo / thermal dual-curing bio-based UV ink composition according to claim 6, characterized in that, The eugenol-furfurylamine type benzoxazine monomer was prepared according to the following method: Eugenol and furfural are added to paraformaldehyde, and the mixture is stirred at 100-120°C for 1.5-3 hours. Finally, the mixture is washed, dried, filtered, and rotary evaporated to obtain the final product.

8. The photo / thermal dual-curing bio-based UV ink composition according to claim 1, characterized in that, The reactive diluent comprises ethoxyethoxyethyl acrylate and 1,6-hexanediol diacrylate in a mass ratio of (1-3):

1.

9. The photo / thermal dual-curing bio-based UV ink composition according to claim 1, characterized in that, The curing method for the UV ink composition is a dual curing method, specifically including the following steps: First curing: The UV ink composition is coated onto the surface of the substrate and then irradiated with UV light to form a pre-cured coating, thus obtaining a pre-treated substrate; Second curing: Place the pretreated substrate at 100-150℃ for 5-30 minutes to cure completely.

10. A method for preparing a photo / thermal dual-curing bio-based UV ink composition, used to prepare the photo / thermal dual-curing bio-based UV ink composition according to any one of claims 1 to 9, characterized in that, The process includes the following steps: Mix all raw materials under light-protected conditions, stir at 500–1500 rpm for 20–60 minutes, and finally filter to obtain the final product.

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