An epoxy acrylate / itaconic acid derivative hybrid photocurable coating composition, a method for preparing the same, a photocured coating layer and applications thereof

Abstract

The present application relates to the technical fields of high polymer material and ultraviolet (UV) curing coating, and particularly relates to an epoxy acrylate / itaconic acid derivative composite photocuring coating composition, a preparation method thereof, a photocuring coating layer and application.The photocuring coating composition comprises the following components in parts by mass: an epoxy acrylate / itaconic acid derivative composite photocuring resin: 40-80 parts; an active diluent: 20-60 parts; and a photoinitiator: 1-8 parts.The present application provides a bio-based monomer IG with high crosslinking activity, a green catalyst-free and solvent-free preparation method of the bio-based monomer IG, and an innovative petroleum-based / bio-based resin composite strategy and a coating composition thereof, so that the mechanical strength of the petroleum-based EA is efficiently enhanced, and meanwhile, the mechanical properties of the composite system still maintain a high level after the active diluent is added, the application range of the EA is expanded, and the petroleum-based resin is modified to be green and high-performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and ultraviolet (UV) curable coatings, and particularly to an epoxy acrylate / itaconic acid derivative composite UV-curable coating composition, its preparation method, UV-curable coating, and its application. Background Technology

[0002] With increasing global emphasis on sustainable development and environmental protection, developing high-performance polymer materials using renewable biomass resources to replace traditional petroleum-based products has become an important research direction in polymer science and the coatings industry. UV curing technology, due to its advantages such as high efficiency, energy saving, and low volatile organic compound (VOC) emissions, is widely used in coatings, inks, and adhesives. Petroleum-based epoxy acrylates (EA) have become the mainstream resin in UV-cured coatings, inks, and adhesives due to their fast curing rate, excellent adhesion, and good film-forming properties. However, traditional petroleum-based EA has curing defects: high molecular chain rigidity, extremely high viscosity, and low crosslinking density after curing. This usually requires the addition of large amounts of reactive diluents to reduce its viscosity. Monofunctional and difunctional diluents, due to their low viscosity, strong dilution ability, and ability to provide a certain degree of flexibility, are commonly used in petroleum-based resin systems. However, the addition of large amounts of reactive diluents usually leads to a decrease in the mechanical properties of the system, making it difficult to meet the requirements of high-end applications in terms of core mechanical properties such as tensile strength and elastic modulus. With increasing global demands for sustainable development and environmental protection, utilizing renewable biomass resources to modify petroleum-based polymer materials to achieve the dual goals of "greening + high performance" has become an important direction for industry development.

[0003] Itaconic acid (IA) is an abundant and inexpensive platform bio-based chemical that can be produced through glucose fungal fermentation. Its molecular structure contains one conjugated double bond and two carboxyl groups, similar to the structure of the petroleum-based monomer methacrylic acid. It possesses extremely high reactivity and functionalization potential, making it an ideal candidate for preparing high-performance bio-based polymers. Currently, research has explored the use of itaconic acid in the synthesis of UV-curable resins such as polyurethane acrylates (PUA) and unsaturated polyesters (UPE). For example, Chinese patent document CN113667106A discloses an itaconic acid-based polyester resin prepared by melt polycondensation of a small-molecule polyol, itaconic acid, and a diacid. However, this type of resin exhibits insufficient surface hardness (e.g., pencil hardness) in the cured coating, and its high viscosity makes it difficult to achieve a good balance between processing flowability and final mechanical properties. Another example is Chinese patent document CN114369027A, which developed a series of itaconic acid diester-type UV-curable monomers. Although these monomers exhibit good reactivity, their synthetic routes involve organic solvents and catalysts, and the post-processing steps are cumbersome, increasing process complexity and production costs, and potentially introducing impurities and environmental burdens. Existing technologies also include photocurable systems using itaconic acid-modified hyperbranched polyglycidyl ether as raw materials, such as CN111607098A. However, the product is a highly polymerized hyperbranched polymer without a clearly symmetrical structure; its core function is only to improve adhesion to glass substrates, without mentioning the mechanical strength of the coating. Furthermore, its curing relies on the synergistic effect of mercaptosiloxane and isocyanate curing agents. Another example is the photocurable oligomer obtained by stepwise esterification of itaconic acid, epoxidized soybean oil, and glycidyl methacrylate in Chinese patent document CN113416610A. The resulting oligomer lacks a fixed molecular configuration and exhibits poor mechanical strength. In the prior art, there are reports on the preparation of itaconic acid acrylate by ring-opening reaction of itaconic acid and glycidyl methacrylate (such as CN113292516A). This technology chemically grafts the prepared itaconic acid acrylate with epoxidized soybean oil acrylate, demonstrating the high activity of itaconic acid acrylate. However, the preparation steps are complicated, the product has no fixed molecular configuration, and its application in bio-based coatings has only been explored, without addressing the enhancement of mechanical properties of petroleum-based epoxy acrylate systems.

[0004] To address the above issues, there is an urgent need to develop a novel resin system design strategy and synthesis method that can simultaneously improve crosslinking density and prevent the decrease in mechanical properties caused by the addition of diluents. Summary of the Invention

[0005] This invention provides an epoxy acrylate / itaconic acid derivative composite photocurable coating composition, its preparation method, photocurable coating, and applications. The aim is to address the following technical problems: First, existing itaconic acid derivative preparation requires a catalyst, leaving residues and involving cumbersome post-processing; second, traditional petroleum-based epoxy acrylate resins (EA) have limited crosslinking density and insufficient core mechanical properties such as tensile strength, elastic modulus, and pencil hardness, making them unsuitable for high-end applications. To address these shortcomings, this invention provides a highly crosslinking-active bio-based monomer IG, its green, catalyst-free, and solvent-free preparation method, and an innovative petroleum-based / bio-based resin composite strategy and its coating composition. This achieves efficient enhancement of the mechanical strength of petroleum-based EA while ensuring that the composite system maintains high mechanical properties even after the addition of an active diluent, expanding the application range of EA and realizing the greening and high-performance modification of petroleum-based resins.

[0006] To achieve the above objectives, the present invention provides an epoxy acrylate / itaconic acid derivative composite photocurable coating composition, wherein the photocurable coating composition comprises the following components in parts by weight: Epoxy acrylate / itaconic acid derivative composite photocurable resin: 40-80 parts; Reactive diluent: 20-60 parts; Photoinitiator: 1-8 parts; The epoxy acrylate / itaconic acid derivative composite photocurable resin comprises epoxy acrylate and itaconic acid derivative monomers, wherein the mass ratio of epoxy acrylate to itaconic acid derivative monomers is 9:1 to 5:5. The reactive diluent is an acrylate reactive diluent with monofunctional or difunctional groups.

[0007] This invention provides an epoxy acrylate / itaconic acid derivative composite photocurable coating composition. The composition comprises an epoxy acrylate / itaconic acid derivative composite photocurable resin and an reactive diluent. Based on the EA / IG composite resin system, it can enhance the mechanical strength of the cured system. Furthermore, when the reactive diluent is added to adjust the viscosity of the system, since IG can react with the reactive diluent, the decrease in mechanical properties of the cured coating caused by the addition of the reactive diluent is much smaller than that of pure EA resin.

[0008] Under this premise, the present invention also provides an epoxy acrylate / itaconic acid derivative composite photocurable resin. This composite resin is prepared by blending IG monomer obtained by the aforementioned method with petroleum-based epoxy acrylate (EA, preferably bisphenol A type epoxy acrylate) at a specific mass ratio. The petroleum-based epoxy acrylate, due to its rigid structure of benzene rings and epoxy open rings, exhibits extremely high viscosity after curing, possessing a certain crosslinking density but limited mechanical strength. The preferred mass ratio of EA to IG is 9:1 to 5:5. Through this composite, IG, as a small-molecule functional modified monomer, can not only fill the gaps between EA molecules and reduce intermolecular forces to achieve viscosity reduction, but also participate in crosslinking through trifunctional double bonds to form a high-density three-dimensional network to enhance mechanical strength.

[0009] The reactive diluent of the present invention is a monofunctional or difunctional acrylate reactive diluent. The acrylate groups can react with the unsaturated double bonds in the epoxy acrylate / itaconic acid derivative composite photocurable resin, thereby minimizing the decrease in the mechanical properties of the system caused by the addition of the diluent.

[0010] Preferably, the chemical structural formula of the itaconic acid derivative monomer is as follows: .

[0011] The itaconic acid derivative monomer of this invention has a small molecular structure, thus exhibiting low viscosity. Simultaneously, its compact and symmetrical structure, containing three unsaturated carbon-carbon double bonds, provides high photocurability. The trifunctional double bonds synergistically crosslink with EA, significantly increasing the crosslinking density of the system. This structurally achieves directional enhancement of EA's tensile strength, elastic modulus, and pencil hardness, resulting in superior mechanical properties compared to traditional petroleum-based EA. This lays the structural foundation for achieving high crosslinking density and enhanced mechanical properties in the system. This structure is fundamentally different from high-polymerization-degree resins in the prior art and also differs from the long-chain or asymmetric structures of other itaconic acid-based resins.

[0012] Preferably, the itaconic acid derivative monomer is prepared by itaconic acid and glycidyl methacrylate under catalyst-free conditions through ring-opening esterification reaction. The monomer has a small molecular structure containing three unsaturated carbon-carbon double bonds and has a symmetrical molecular structure.

[0013] This invention aims to synthesize a high-performance bio-based monomer (IG) through molecular design. The synthesis process is green and simple, requiring no catalyst. The synergistic effect of IG in composites with traditional petroleum-based epoxy acrylate resin (EA) is explored, along with its performance in a system with added reactive diluents. By investigating the influence of IG on key mechanical properties of the cured EA coating, such as tensile strength, elastic modulus, and pencil hardness, this invention achieves high-performance, green modification of petroleum-based EA, providing a novel solution for next-generation, easily processable, high-performance, and environmentally friendly photocurable materials.

[0014] Preferably, the ring-opening esterification reaction is carried out in the presence of a polymerization inhibitor and under an inert atmosphere, wherein the polymerization inhibitor includes at least one of hydroquinone, p-hydroxyanisole, o-methylanisole, p-benzoquinone, or 2,6-tert-butyl-4-methylphenol.

[0015] Preferably, the reactive diluent includes at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, neopentyl glycol diacrylate, isobornyl acrylate, or caprolactone acrylate.

[0016] Preferably, the photoinitiator includes at least one of 2-hydroxy-2-methylphenylacetone, trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-4-(2-hydroxyethylphenyl)-2-methylphenylacetone, or 1-hydroxyphenylethylacetophenone.

[0017] Under the same technical concept, the present invention also provides a method for preparing an epoxy acrylate / itaconic acid derivative composite photocurable coating composition, comprising the following steps: S1. Preparation of itaconic acid derivative monomers; S2 The itaconic acid derivative monomer is mixed with epoxy acrylate to obtain epoxy acrylate / itaconic acid derivative composite photocurable resin; S3. Mix the epoxy acrylate / itaconic acid derivative composite photocurable resin, reactive diluent, and photoinitiator to obtain a photocurable coating.

[0018] Preferably, the preparation of itaconic acid derivative monomers in S1 specifically includes: S1.1 Under an inert atmosphere, preheat the glycidyl methacrylate containing the polymerization inhibitor to 50℃~70℃; S1.2 Add itaconic acid to the system from step S1.1 and stir until the system is clear; S1.3. Heat the reaction system to 95℃ to 120℃ to carry out the ring-opening esterification reaction. The temperature is 95℃~110℃ and the reaction time is 9~13 hours. The reaction progress is tracked by monitoring the acid value of the system. S1.4 When the acid value drops below 10 mg KOH / g, the reaction is stopped to obtain the itaconic acid derivative monomer.

[0019] Under the same technical concept, the present invention also provides an epoxy acrylate / itaconic acid derivative composite photocurable coating, wherein the curable coating is formed by curing the coating composition or the coating composition prepared by the preparation method described above by ultraviolet light irradiation.

[0020] Under the same technical concept, the present invention also provides the application of an epoxy acrylate / itaconic acid derivative composite photocurable coating composition in the preparation of UV-curable coatings, 3D printing photosensitive resins or adhesives.

[0021] The above-described solution of the present invention has the following beneficial effects: (1) This invention provides an epoxy acrylate / itaconic acid derivative composite UV-curable coating composition with a wide viscosity range that can be adjusted. It is suitable for fields with high requirements for mechanical strength and surface hardness, such as high-performance wood coatings, metal protective coatings, plastic coatings and their 3D printing photosensitive resins, providing a new solution for developing next-generation high-performance and sustainable UV-curable materials. (2) This invention designs a composite system of epoxy acrylate / itaconic acid derivative composite photocurable coating composition, consisting of epoxy acrylate / itaconic acid derivative composite photocurable resin and reactive diluent. This system exhibits superior performance and significant advantages: the trifunctional double bonds synergistically crosslink with EA significantly increase the crosslinking density of the system, structurally achieving directional enhancement of EA's tensile strength, elastic modulus, and pencil hardness, resulting in superior mechanical properties compared to traditional petroleum-based EA. Furthermore, based on the EA / IG composite resin system, when different amounts of reactive diluent are added to adjust the system viscosity, the decrease in the mechanical properties of the cured coating is far less than that of pure EA resin, meeting the formulation adjustment needs of different application scenarios.

[0022] (3) The synthesis process of this invention is green and efficient: The preparation method of this invention adopts a one-pot reaction without catalysts or solvents. The steps are simple, and there is no need to use organic solvents and heavy metal catalysts. The reaction conditions are mild and controllable, and the post-processing is simple, which conforms to the principles of green chemistry. Moreover, the conversion rate is high (>96%), which is easy to realize industrial production. It is fundamentally different from the existing technology that requires catalysts and high-temperature reactions, and avoids the problems of catalyst residue and complicated post-processing. Attached Figure Description

[0023] Figure 1 These are the infrared spectra of the raw materials and the final product used in the synthesis of IG in Examples 1-2 of the itaconic acid derivative monomer synthesis of this invention.

[0024] Figure 2 This is the 1H NMR spectrum of IG synthesized in Example 1-2 of the synthesis of itaconic acid derivative monomers in this invention.

[0025] Figure 3 These are the infrared spectra of the UV-curable coating composition in Example 3 of the present invention before curing and after curing for 180 seconds.

[0026] Figure 4The viscosity performance test graphs are for the photocurable coatings prepared in Examples 1-10 and Comparative Examples 1-6 of this invention.

[0027] Figure 5 The graphs show the gel content test performance of the photocurable coatings prepared in Examples 1-10 and Comparative Examples 1-6 of this invention. Detailed Implementation

[0028] To make the technical problems, solutions, and advantages of this invention clearer, a detailed description will be provided below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a locking connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] 1. Raw materials Itaconic acid (IA), glycidyl methacrylate (GMA), 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), and 2-hydroxy-2-methyl-1-phenylpropanone (photoinitiator 1173) were purchased from Shanghai E. En Chemical Technology Co., Ltd.

[0033] Hydroquinone (HQ) and p-hydroxyanisole (MEHQ) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0034] Bisphenol A type epoxy acrylate (E51-AA) was purchased from Guangdong Haohui New Materials Co., Ltd.

[0035] 2. Testing Methods Infrared spectroscopy (FT-IR) was performed using a Nicolet 6700 Fourier transform infrared spectrometer from Thermo Fisher Scientific, Inc.

[0036] 1H NMR spectrum ( 1 H NMR was measured using a German Bruker AVANCE NEO nuclear magnetic resonance spectrometer.

[0037] Tensile properties were tested according to the national standard GB / T 2567-2021, using a C45.105 material testing machine from Metersbonwe Industrial Systems (China) Co., Ltd. Stress-strain curve measurement: After curing, the sample was subjected to increased load at a tensile speed of 5 mm / min at 25℃.

[0038] The viscosity of oligomers and the coatings prepared from them was measured using an NDJ-8S digital viscometer (Shanghai Hengping Instrument Co., Ltd., China).

[0039] The pencil hardness of the coating prepared by the paint was measured using a QHQ-A type pencil hardness tester (Dongguan Huaguo Precision Instruments Co., Ltd., China).

[0040] The gel content test is performed according to standard methods. The cured coating film is weighed and recorded as m. i Immerse in toluene for 24 hours, remove, dry, and weigh. Record the weight as m. f According to the formula Gel Content = (m f / m i Calculate by multiplying by 100%.

[0041] Example 1 Synthesis Case 1 of Itaconic Acid Derivative Monomers This synthetic example presents a method for preparing itaconic acid-derived monomer IG, which mainly includes the following steps: S1. Add 14.22g of glycidyl methacrylate and 0.05g of hydroquinone to a three-necked flask equipped with a stirrer, thermometer, and condenser, and preheat to 60°C under argon protection; the amount of hydroquinone added is 2.0% of the total mass of itaconic acid and glycidyl methacrylate. S2. While stirring, add 13.01g of itaconic acid solid to the three-necked flask in batches, keeping the temperature at 60-70℃, until the system becomes a homogeneous and transparent liquid; S3. Slowly raise the temperature of the reaction system to 95°C and continue the reaction at this temperature for 13 hours. During this period, take samples every hour and determine the acid value of the system using acid-base titration. S4. When the reaction proceeds for 13 hours and the acid value drops below 10 mg KOH / g, the reaction is stopped. A pale yellow, transparent, viscous liquid is obtained, which is the target product, IG monomer. This IG monomer is named itaconic acid-derived monomer 1.

[0042] Case Study 2: Synthesis of Itaconic Acid Derivative Monomers This synthetic example presents a method for preparing itaconic acid-derived oligomers IG, which mainly includes the following steps: S1. Add 14.22g of glycidyl methacrylate and 0.08g of p-hydroxyanisole to a three-necked flask equipped with a stirrer, thermometer, and condenser, and preheat to 70°C under argon protection; the amount of p-hydroxyanisole added is 3.0% of the total mass of itaconic acid and glycidyl methacrylate. S2. While stirring, add 13.01g of itaconic acid solid to the three-necked flask in batches, keeping the temperature at 60-70℃, until the system becomes a homogeneous and transparent liquid; S3. Slowly heat the reaction system to 105℃ and continue the reaction at this temperature for 11 hours. Take samples every hour during this period and determine the acid value of the system using acid-base titration. S4. When the reaction proceeds for 11 hours and the acid value drops below 10 mg KOH / g, the reaction is stopped. A pale yellow, transparent, viscous liquid is obtained, which is the target product, IG monomer. This IG monomer is named itaconic acid-derived monomer 2.

[0043] Figure 1 These are the infrared spectra of the raw materials and the final product used in the synthesis of IG in Examples 1-2.

[0044] Figure 2 This is the hydrogen NMR spectrum of synthesized IG in Synthesis Examples 1-2.

[0045] Combination Figure 1 , 2 The spectrum allows us to determine the chemical structural formula of the itaconic acid derivative monomer: .

[0046] 0.8 g of itaconic acid derivative monomer (IG) synthesized in Synthesis Case 1 and 7.2 g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 8 g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0047] After pre-mixing the following raw material components in a mixer according to the parts by weight, homogenize them for 30 minutes to obtain the UV-cured coating: 8g of epoxy acrylate / itaconic acid derivative composite light-curing resin; Reactive diluent (TPGDA) 2.0g; Photoinitiator (1173) 0.6g.

[0048] Example 2: 1.6 g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 6.4 g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 8 g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0049] After pre-mixing the following raw material components in a mixer according to the parts by weight, homogenize them for 30 minutes to obtain the UV-cured coating: 8g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (TPGDA) 2.0g, Photoinitiator (1173) 0.6g.

[0050] Example 3 2.4 g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 5.6 g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 8 g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0051] In this embodiment 3, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes to obtain a light-curing coating: 8g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (TPGDA) 2.0g, Photoinitiator (1173) 0.6g.

[0052] Figure 3 These are the infrared spectra of the UV-curable coating composition in Example 3 before curing and after curing for 180 seconds.

[0053] Example 4 3.2g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 4.8g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 8g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0054] In this embodiment 4, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes to obtain a light-curing coating: 8g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (TPGDA) 2.0g, Photoinitiator (1173) 0.6g.

[0055] Example 5 4g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 4g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 8g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0056] In Example 5, the following raw material components are pre-mixed in a mixer according to their weight parts, and then homogenized for 30 minutes using a homogenizer to obtain a light-curing coating: 8g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (TPGDA) 2.0g, Photoinitiator (1173) 0.6g.

[0057] Example 6 1.8 g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 4.2 g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 6 g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0058] In this embodiment 6, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes to obtain a light-curing coating: 6g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (TPGDA) 4.0g, Photoinitiator (1173) 0.6g.

[0059] Example 7 1.2g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 2.8g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 4g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0060] In this embodiment 7, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes using a homogenizer to obtain a light-curing coating: 4g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (TPGDA) 6.0g, Photoinitiator (1173) 0.6g.

[0061] Example 8 2.4 g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 5.6 g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 8 g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0062] In this embodiment 8, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes to obtain a light-curing coating: 8g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (HDDA) 2.0g, Photoinitiator (1173) 0.6g.

[0063] Example 9 1.8 g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 4.2 g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 6 g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0064] In this embodiment 9, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes using a homogenizer to obtain a light-curing coating: 6g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (HDDA) 4.0g, Photoinitiator (1173) 0.6g.

[0065] Example 10 1.2g of itaconic acid derivative monomer (IG) synthesized in Example 1 and 2.8g of bisphenol A type epoxy acrylate (EA) were mixed to obtain 4g of epoxy acrylate / itaconic acid derivative composite photocurable resin.

[0066] In this embodiment 10, the following raw material components are pre-mixed in a mixer according to the weight parts, and then homogenized for 30 minutes using a homogenizer to obtain a light-curing coating: 4g of epoxy acrylate / itaconic acid derivative composite light-curing resin Reactive diluent (HDDA) 6.0g, Photoinitiator (1173) 0.6g.

[0067] Comparative Example 1: Compared with Example 1, this comparative example uses bisphenol A type epoxy acrylate (E51-AA) as the oligomer, while other raw materials and preparation steps are the same as in Example 1.

[0068] Comparative Example 2 Compared with Example 6, this comparative example uses bisphenol A type epoxy acrylate (E51-AA) as the oligomer, while other raw materials and preparation steps are the same as in Example 2.

[0069] Comparative Example 3 Compared with Example 7, this comparative example uses bisphenol A type epoxy acrylate (E51-AA) as the oligomer, while other raw materials and preparation steps are the same as in Example 3.

[0070] Comparative Example 4 Compared with Example 8, this comparative example uses bisphenol A type epoxy acrylate (E51-AA) as the oligomer, while other raw materials and preparation steps are the same as in Example 8.

[0071] Comparative Example 5 Compared with Example 9, this comparative example uses bisphenol A type epoxy acrylate (E51-AA) as the oligomer, while other raw materials and preparation steps are the same as in Example 9.

[0072] Comparative Example 6 Compared with Example 10, this comparative example uses bisphenol A type epoxy acrylate (E51-AA) as the oligomer, while other raw materials and preparation steps are the same as in Example 10.

[0073] The performance of the photocurable coatings of Examples 1-10 and Comparative Examples 1-6 was tested according to the test scheme of GB / T 2567-2021, and the test results are shown in Table 1.

[0074] Figure 4 The viscosity performance test graphs are for the photocurable coatings prepared in Examples 1-10 and Comparative Examples 1-6 of this invention.

[0075] Figure 5 The graphs show the gel content test performance of the photocurable coatings prepared in Examples 1-10 and Comparative Examples 1-6 of this invention.

[0076] Based on the above test data, it can be concluded that within the range of IG / EA mass ratio of 9:1 to 5:5 (Examples 1-5), as the proportion of IG monomer added increases, the tensile strength, elastic modulus, pencil hardness, and gel content of the composite system continuously improve, reaching the optimal value at 5:5. This proves that the trifunctional double bonds of the IG monomer significantly improve the crosslinking density of the EA system, thereby enhancing its mechanical properties.

[0077] Figure 4The carbon-carbon double bond peaks significantly decreased after photocuring, confirming that EA, IG, and the reactive diluent all participated in the photocuring reaction and jointly formed a crosslinked system. Examples 3, 6, and 7 are systems with different TPGDA diluent ratios, and their mechanical properties are far superior to the pure EA system (Comparative Examples 1-3), with no decrease in pencil hardness. Examples 8-10 are systems with different HDDA diluent amounts, and Comparative Examples 4-6 are pure EA systems with different HDDA diluent amounts. The mechanical properties and pencil hardness of Examples 8-10 with added IG are superior to those of Comparative Examples 4-6 without added IG. At the same time, with the increase of diluent amount, the decrease in mechanical properties of the EA / IG mixed system with added IG is significantly smaller than that of the pure EA system without added IG, proving that the EA / IG composite system has excellent mechanical stability and solves the problem of severe mechanical property degradation after adding reactive diluent to the pure EA system.

[0078] The gel content in all embodiments was significantly higher than that in the pure EA system, fully demonstrating the inherent advantages of IG monomers in forming high-strength, high-rigidity coatings. IG monomers, through their unique small molecule configuration, enhance the crosslinking density of the EA system, constructing a dense and orderly three-dimensional crosslinking network, which is the fundamental reason for its high strength and high hardness.

[0079] In summary, the system's test data consistently and strongly demonstrate that, compared with existing technologies, the itaconic acid-based photosensitive monomer synthesis process provided by this invention is green and catalyst-free. When blended with traditional petroleum-based photosensitive oligomer epoxy acrylates in a specific ratio, it achieves a significant improvement in key mechanical properties (strength, modulus) and surface hardness, while effectively reducing the system's viscosity. Even with the addition of a large amount of monofunctional or difunctional reactive diluents for adjustment, it still maintains high mechanical properties. This successfully solves the technical problem of insufficient mechanical properties in petroleum-based photocurable systems due to low crosslinking density, and also addresses the significant reduction in mechanical properties caused by the addition of large amounts of reactive diluents. It provides an innovative and feasible solution for the high-performance and green modification of petroleum-based epoxy acrylates.

[0080] Table 1

Claims

1. A composite photocurable coating composition of epoxy acrylate / itaconic acid derivative, characterized in that, The UV-curable coating composition comprises the following components in parts by weight: Epoxy acrylate / itaconic acid derivative composite photocurable resin: 40-80 parts; Reactive diluent: 20-60 parts; Photoinitiator: 1-8 parts; The epoxy acrylate / itaconic acid derivative composite photocurable resin comprises epoxy acrylate and itaconic acid derivative monomers, wherein the mass ratio of epoxy acrylate to itaconic acid derivative monomers is 9:1 to 5:

5. The reactive diluent is an acrylate reactive diluent with monofunctional or difunctional groups.

2. The photocurable coating composition according to claim 1, characterized in that, The chemical structural formula of the itaconic acid derivative monomer is as follows: .

3. The photocurable coating composition according to claim 2, characterized in that, The itaconic acid derivative monomer is prepared by ring-opening esterification of itaconic acid and glycidyl methacrylate under catalyst-free conditions. The monomer has a small molecular structure containing three unsaturated carbon-carbon double bonds and has a symmetrical molecular structure.

4. The photocurable coating composition according to claim 2, characterized in that, The ring-opening esterification reaction is carried out in the presence of a polymerization inhibitor and under an inert atmosphere. The polymerization inhibitor includes at least one of hydroquinone, p-hydroxyanisole, o-methylanisole, p-benzoquinone, or 2,6-tert-butyl-4-methylphenol.

5. The photocurable coating composition according to claim 1, characterized in that, The reactive diluent includes at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, neopentyl glycol diacrylate, isobornyl acrylate, or caprolactone acrylate.

6. The photocurable coating composition according to claim 1, characterized in that, The photoinitiator includes at least one of 2-hydroxy-2-methylphenylacetone, trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-4-(2-hydroxyethylphenyl)-2-methylphenylacetone, or 1-hydroxyphenylethylacetophenone.

7. A method for preparing an epoxy acrylate / itaconic acid derivative composite photocurable coating composition, characterized in that, Includes the following steps: S1. Preparation of itaconic acid derivative monomers; S2 The itaconic acid derivative monomer is mixed with epoxy acrylate to obtain epoxy acrylate / itaconic acid derivative composite photocurable resin; S3. Mix the epoxy acrylate / itaconic acid derivative composite photocurable resin, reactive diluent, and photoinitiator to obtain a photocurable coating.

8. The photocurable coating composition according to claim 7, characterized in that, S1 specifically includes the preparation of itaconic acid derivative monomers: S1.1 Under an inert atmosphere, preheat the glycidyl methacrylate containing the polymerization inhibitor to 50℃~70℃; S1.2 Add itaconic acid to the system from step S1.1 and stir until the system is clear; S1.

3. Heat the reaction system to 95℃ to 120℃ to carry out the ring-opening esterification reaction. The temperature is 95℃~110℃ and the reaction time is 9~13 hours. The reaction progress is tracked by monitoring the acid value of the system. S1.4 When the acid value drops below 10 mg KOH / g, the reaction is stopped to obtain the itaconic acid derivative monomer.

9. A composite photocurable coating of epoxy acrylate / itaconic acid derivative, characterized in that, The cured coating is formed by curing the coating composition according to any one of claims 1-6 or the coating composition prepared by the preparation method according to any one of claims 7-8 under ultraviolet light.

10. The application of an epoxy acrylate / itaconic acid derivative composite photocurable coating composition in the preparation of UV-curable coatings, 3D printing photosensitive resins or adhesives.

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