Uv-curable primer hybrid prepolymer coating and methods of making and using the same
By introducing macromolecular photoinitiators into raw lacquer and forming an interpenetrating polymer network, the problems of slow curing and high brittleness of raw lacquer coatings are solved, achieving efficient and stable UV-cured raw lacquer coatings and improving the flexibility and compatibility of the coatings.
Patent Information
- Application Number
- CN202610351403.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-21
- Publication Date
- 2026-06-26
AI Technical Summary
Traditional raw lacquer has a slow curing time, the curing agent is prone to migration, the coating is brittle, and it has poor compatibility with acrylic resins, resulting in poor coating performance.
By employing a macromolecular photoinitiator design, photoinitiating groups are fixed onto the rosin backbone through chemical bonds. A comb-like branched hybrid prepolymer is formed through a controlled free radical grafting process, which improves compatibility and forms an interpenetrating polymer network.
It achieves efficient UV curing of coatings, reduces photoinitiator migration, improves the storage stability and overall performance of coatings, overcomes coating brittleness, and enhances curing efficiency and flexibility.
Smart Images
Figure CN122278245A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biomass-based UV-curable coating technology, specifically a UV-curable lacquer hybrid prepolymer coating and its preparation method. The coating uses rosin acid as the backbone and benzophenone as a macromolecular photoinitiator with side chain anchoring. Urushiol is introduced into the same molecular chain through controlled free radical grafting to form a "rigid-tough tunable lacquer hybrid prepolymer", achieving a green coating with low migration, high toughness, and UV curability. Background Technology
[0002] Raw lacquer is a high-quality coating secreted by natural lacquer trees. It boasts excellent adhesion, durability, chemical resistance, and unique decorative effects, earning it the title of "King of Coatings." However, traditional raw lacquer has the following inherent drawbacks: First, its curing relies on laccase catalysis, resulting in a long natural drying time (usually more than 24 hours) and significant influence from temperature and humidity. Second, the urushiol compounds it contains can easily cause skin allergies. Third, pure raw lacquer coatings are relatively brittle, and their impact resistance needs improvement.
[0003] Ultraviolet (UV) curing technology boasts advantages such as fast curing rate, low energy consumption, and no solvent evaporation, making it an important direction for the development of green coatings. Applying UV curing technology to the modification of raw lacquer holds promise for solving its bottleneck problem of slow curing. However, existing UV raw lacquer modification technologies mostly employ physical blending to add small-molecule photoinitiators (such as benzophenone, 1173, etc.), which presents the following problems: small-molecule photoinitiators easily migrate to the coating surface or the interior of the substrate, not only reducing curing efficiency but also potentially causing toxic residues and odors; simultaneously, raw lacquer has poor compatibility with acrylic resins, and simple blending easily leads to phase separation, affecting coating transparency and performance.
[0004] Therefore, developing a UV-curable lacquer system that is compatible with raw lacquer, has photoinitiating groups fixed on the molecular chain that are not easily migrated, and combines rigidity and flexibility is of great theoretical significance and application value. Summary of the Invention
[0005] The purpose of this invention is to address the problems of slow curing of raw lacquer, easy migration of small molecule photoinitiators, and high brittleness of coatings in the prior art, and to provide a UV-curable raw lacquer hybrid prepolymer coating. This coating adopts a design with a macromolecular photoinitiator, and the initiating groups are fixed on the rosin skeleton by chemical bonds, which fundamentally solves the migration problem. Furthermore, the compatibility is improved through a "pre-grafting" process, giving the coating excellent comprehensive performance.
[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:
[0007] A UV-curable raw lacquer hybrid prepolymer coating comprises the following components:
[0008] Rosin acid, hydroxyethyl acrylate, p-toluenesulfonic acid, polymerization inhibitor, 4-acryloyloxybenzophenone, polyethylene glycol methyl ether acrylate, azobisisobutyronitrile, refined raw lacquer, crosslinking agent, leveling agent, and defoamer.
[0009] As a further improvement of the present invention, the coating is prepared from raw materials comprising the following parts by weight:
[0010] 4-8 parts rosin acid, 2-4 parts hydroxyethyl acrylate, 0.05-0.2 parts p-toluenesulfonic acid, 0.01-0.05 parts polymerization inhibitor, 1-2 parts 4-acryloyloxybenzophenone (ABP), 1.5-3 parts polyethylene glycol methyl ether acrylate, 0.1-0.3 parts azobisisobutyronitrile, 70-80 parts refined raw lacquer, 8-12 parts crosslinking agent, 0.2-0.8 parts leveling agent, 0.2-0.8 parts defoamer.
[0011] As a further improved technical solution of the present invention, the molecular weight of the polyethylene glycol methyl ether acrylate is 400~600; the polymerization inhibitor is hydroquinone; the crosslinking agent is trimethylolpropane triacrylate; the azobisisobutyronitrile is recrystallized; the leveling agent is polyether-modified polysiloxane; and the defoamer is a non-silicone polymer defoamer.
[0012] To achieve the above-mentioned technical objectives, another technical solution adopted by the present invention is as follows:
[0013] A method for preparing the UV-curable raw lacquer hybrid prepolymer coating includes the following steps:
[0014] (1) Synthesis of rosin acid ethyl acrylate (RAE): Rosin acid, hydroxyethyl acrylate, p-toluenesulfonic acid and polymerization inhibitor are mixed and reacted under a protective atmosphere. After post-treatment, RAE is obtained.
[0015] (2) Synthesis of flexible rosin-based macromolecular photoinitiator Flexible Rosin-g-BP: The RAE, 4-acryloyloxybenzophenone and polyethylene glycol methyl ether acrylate obtained in step (1) were dissolved in anhydrous tetrahydrofuran, and azobisisobutyronitrile was added. The reaction was carried out under a protective atmosphere, and after precipitation and drying, Flexible Rosin-g-BP was obtained.
[0016] (3) Premixing: Under light-protected conditions, the refined raw lacquer, the Flexible Rosin-g-BP obtained in step (2), the crosslinking agent, the leveling agent and the defoamer are mixed evenly to obtain a mixture;
[0017] (4) UV pre-irradiation grafting: The mixture obtained in step (3) is subjected to UV pre-irradiation at low temperature until the viscosity of the system increases but does not reach the gel point, thus obtaining a raw lacquer-based UV-curable hybrid prepolymer coating.
[0018] (5) Post-processing and storage: Store the prepolymer coating obtained in step (4) under light-proof and low-temperature conditions.
[0019] As a further improvement of the present invention, step (1) includes:
[0020] Rosin acid, hydroxyethyl acrylate, p-toluenesulfonic acid, and hydroquinone were added to a four-necked flask and reacted at 110-120°C for 4-6 hours under nitrogen protection. The reaction progress was tracked by measuring the acid value. After the reaction was completed, the mixture was cooled, washed with dilute alkali solution, washed with water until neutral, and excess hydroxyethyl acrylate was removed by vacuum distillation to obtain a pale yellow viscous liquid, RAE.
[0021] As a further improvement of the present invention, step (2) includes:
[0022] RAE, 4-acryloyloxybenzophenone, and polyethylene glycol methyl ether acrylate were dissolved in anhydrous tetrahydrofuran, and azobisisobutyronitrile was added. After purging with nitrogen for 30 minutes to remove oxygen, the mixture was stirred in an oil bath at 65-70°C for 8-12 hours. After the reaction was completed, the solution was added dropwise to cold n-hexane to precipitate the precipitate. The precipitate was filtered, washed, and dried under vacuum to obtain a pale yellow Flexible Rosin-g-BP.
[0023] As a further improvement of the present invention, step (3) includes:
[0024] Under light-protected conditions, refined raw lacquer, Flexible Rosin-g-BP, trimethylolpropane triacrylate, polyether-modified polysiloxane, and non-silicone polymer defoamer are mixed evenly in a stirrer at a low speed of 300-500 r / min, with the temperature controlled below 25℃.
[0025] As a further improvement of the present invention, step (4) includes:
[0026] The mixture is placed in a low-temperature water bath at 15~20℃ and irradiated for 30~45 seconds with a light intensity of 10~30 mW / cm² using a low-pressure mercury lamp or medium-pressure mercury lamp with a main wavelength of 365nm and a filter, until the viscosity of the system increases significantly but does not reach the gel point, thus obtaining a raw lacquer-based UV-curable hybrid prepolymer.
[0027] Step (5) includes:
[0028] Transfer the prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a low-temperature environment of 0~5℃ away from light.
[0029] To achieve the above-mentioned technical objectives, another technical solution adopted by the present invention is as follows:
[0030] A method for using the aforementioned UV-curable lacquer hybrid prepolymer coating involves coating the prepolymer coating onto the surface of a substrate to form a film, and then curing it with UV light to form a coating layer.
[0031] As a further improvement of the present invention, the thickness of the coating is 20~40 μm; the light intensity of the UV curing is 50~100 mW / cm², and the curing time is 30~90 seconds; the light source of the UV light is a high-pressure mercury lamp or an LED-UV lamp, with a wavelength of 365 nm or 395 nm.
[0032] The beneficial effects of this invention are as follows:
[0033] First, the innovative "biomass-anchored" macromolecular photoinitiator design fundamentally solves the migration problem of UV-cured coatings. This invention innovatively uses the tricyclic diterpenoid hydrogenated phenanthrene structure of natural rosin acid as a rigid framework. Through free radical copolymerization, benzophenone photoinitiating groups are covalently grafted onto the molecular side chains, forming a macromolecular initiator (Macro-PI) with a molecular weight of 5000-10000. The internal mechanism lies in the fact that the rigid hydrophobic structure of the rosin framework not only provides a physical "anchoring" barrier for the photoinitiating groups but also, through chemical bonding, makes benzophenone a permanent component of the molecular chain. This completely eliminates the problems of small-molecule photoinitiators easily migrating to the surface after coating curing, volatilizing and causing odors, or even penetrating the substrate and causing toxic residues. Compared with traditional UV lacquer systems that add small molecule initiators such as benzophenone and 1173, the photoinitiator migration rate of the coating of this invention is reduced to less than 0.05%, which is only 1 / 70 of that of the traditional system. Moreover, the coating has no irritating odor and significantly improves biosafety, making it particularly suitable for fields with stringent safety requirements such as food packaging and interior decoration.
[0034] Secondly, the "controllable pre-grafting" process resolves the compatibility conflict between raw lacquer and acrylic resin through molecular-level chemical bonding. Unlike traditional physical blending, which leads to phase separation, storage stratification, and coating turbidity, this invention employs a low-intensity UV pre-irradiation process. Under the action of an initiator, the double bonds of the macromolecular photoinitiator side chains and the unsaturated bonds of the urushiol side chains in the raw lacquer undergo free radical grafting copolymerization, forming a comb-like branched hybrid prepolymer. The underlying mechanism lies in the precise stopping of this process before the system reaches its gel point. This ensures that the prepolymer retains sufficient reactive groups for subsequent deep curing, while the pre-established chemical bonds significantly improve the compatibility of the two-phase interface, resulting in a homogeneous and stable single-phase system. This innovation extends the coating's storage stability from less than 7 days in traditional blended systems to over 90 days. Furthermore, after coating, there is no need to wait for a lengthy laccase catalysis process; curing is completed in 30-60 seconds under UV irradiation, increasing curing efficiency by more than a thousand times compared to traditional raw lacquer. Simultaneously, it avoids skin allergies caused by urushiol volatilization during raw lacquer application.
[0035] Furthermore, the "rigid-flexible" molecular network design breaks through the performance bottleneck of pure raw lacquer being "hard and brittle." This invention achieves a synergistic effect of enhanced rigidity and compensated toughness at the molecular level: the hydrogenated phenanthrene ring structure of the rosin skeleton acts as a hard segment, providing high cohesive energy and hydrophobicity; the flexible segments of polyethylene glycol methyl ether acrylate act as soft segments, imparting molecular chain mobility; and trimethylolpropane triacrylate provides a suitable crosslinking density. The internal mechanism is manifested in the fact that after curing, the urushiol network and the acrylate network of the raw lacquer form an interpenetrating polymer network (IPN) structure, where stress can be effectively dispersed through the flexible polyether segments, while the rigid ring structure of rosin prevents crack propagation. This structure allows the coating to maintain high hardness (2H~3H) while achieving a flexibility of 1~2 mm (cylindrical bending), and its impact resistance is improved to over 50 kg·cm, far superior to the brittle fracture characteristics of pure raw lacquer, and also overcomes the defect of conventional UV coatings becoming brittle due to high crosslinking.
[0036] More importantly, this invention achieves a balance between "high-efficiency curing" and "green and low-carbon" practices. Compared to traditional raw lacquer, which relies on laccase catalysis, is strictly limited by temperature and humidity, and has a curing time of over 24 hours, this invention shortens the drying time to less than 1 minute through UV curing technology, reduces energy consumption by more than 80%, and does not produce solvent evaporation. At the same time, using rosin and raw lacquer as the main raw materials, with a bio-based content of over 60%, it combines the excellent adhesion (0-1 grade) of raw lacquer with the rapid molding advantages of UV coatings, providing a new environmentally friendly, convenient, and high-performance solution for high-end wood coatings. Attached Figure Description
[0037] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation
[0038] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:
[0039] Example 1:
[0040] This embodiment provides a method for preparing a UV-curable varnish hybrid prepolymer coating, comprising the following steps:
[0041] (1) Synthesis of RAE: 8.0 g of rosin acid, 4.0 g of hydroxyethyl acrylate, 0.15 g of p-toluenesulfonic acid and 0.05 g of hydroquinone were added to a four-necked flask equipped with a stirrer, thermometer, water separator and condenser; the temperature was raised to 110 °C under nitrogen protection and the reaction was carried out for 4 hours until the acid value dropped to below 5 mg KOH / g; after cooling, the mixture was washed with 5% sodium carbonate solution and washed with water until neutral; excess hydroxyethyl acrylate was removed by vacuum distillation to obtain RAE.
[0042] (2) Synthesis of Flexible Rosin-g-BP: The above-synthesized RAE, 1.45 g of 4-acryloyloxybenzophenone, and 2.9 g of polyethylene glycol methyl ether acrylate (molecular weight 500) were dissolved in 50 mL of anhydrous THF. 0.3 g of azobisisobutyronitrile (AIBN) was added. After purging with nitrogen to remove oxygen for 30 minutes, the mixture was reacted in an oil bath at 65 °C for 8 hours. The reaction solution was added dropwise to 500 mL of cold n-hexane to precipitate. The mixture was filtered, washed twice with n-hexane, and dried under vacuum at 40 °C to constant weight to obtain a pale yellow viscous solid, Flexible Rosin-g-BP.
[0043] (3) Preparation of prepolymer coating: Under light-protected conditions, add 70g of refined raw lacquer, the generated Flexible Rosin-g-BP, 12g of trimethylolpropane triacrylate (TMPTA), 0.5g of BYK-333 polyether modified polysiloxane (leveling agent), and 0.65g of BYK-055 non-silicone polymer (defoamer) to a stirrer, stir at 300 r / min for 30 minutes, and control the temperature at 20℃.
[0044] (4) UV pre-irradiation: The mixture is placed in a 15°C water bath and irradiated for 30 seconds with a 365nm low-pressure mercury lamp and a light intensity of 10 mW / cm². The viscosity of the system increases from 25 seconds (Ford-4 cup) to 42 seconds. Irradiation is stopped immediately to obtain the hybrid prepolymer coating.
[0045] (5) Post-processing and storage: Transfer the hybrid prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a light-proof environment at 0°C.
[0046] Example 2:
[0047] (1) Synthesis of RAE: 6.5g of rosin acid, 3.5g of hydroxyethyl acrylate, 0.05g of p-toluenesulfonic acid and 0.01g of hydroquinone were added to a four-necked flask equipped with a stirrer, thermometer, water separator and condenser; the temperature was raised to 120℃ under nitrogen protection and the reaction was carried out for 6 hours until the acid value dropped to below 5 mgKOH / g; after cooling, the mixture was washed with 5% sodium carbonate solution and washed with water until neutral; excess hydroxyethyl acrylate was removed by vacuum distillation to obtain RAE.
[0048] (2) Synthesis of Flexible Rosin-g-BP: The above-synthesized RAE, 1.24 g of 4-acryloyloxybenzophenone, and 3.0 g of polyethylene glycol methyl ether acrylate (molecular weight 500) were dissolved in 50 mL of anhydrous THF. 0.1 g of azobisisobutyronitrile (AIBN) was added, and after purging with nitrogen to remove oxygen for 30 minutes, the mixture was reacted in an oil bath at 70 °C for 12 hours. The reaction solution was added dropwise to 500 mL of cold n-hexane to precipitate the solid. The mixture was filtered, washed twice with n-hexane, and dried under vacuum at 40 °C to constant weight to obtain a pale yellow viscous solid, Flexible Rosin-g-BP.
[0049] (3) Preparation of prepolymer coating: Under light-protected conditions, add 72.5g of refined raw lacquer, the generated Flexible Rosin-g-BP, 11.5g of trimethylolpropane triacrylate (TMPTA), 0.8g of BYK-333 polyether modified polysiloxane (leveling agent), and 0.8g of BYK-055 non-silicone polymer (defoamer) to a stirrer and stir at 500 r / min for 30 minutes, with the temperature controlled at 20℃.
[0050] (4) UV pre-irradiation: The mixture is placed in a 20°C water bath and irradiated for 45 seconds with a 365nm low-pressure mercury lamp and a light intensity of 30 mW / cm². The viscosity of the system increases from 25 seconds (Ford-4 cup) to 42 seconds. Irradiation is stopped immediately to obtain the hybrid prepolymer coating.
[0051] (5) Post-processing and storage: Transfer the hybrid prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a low-temperature environment of 5°C away from light.
[0052] Example 3:
[0053] (1) Synthesis of RAE: 6.0 g of rosin acid, 3.0 g of hydroxyethyl acrylate, 0.13 g of p-toluenesulfonic acid and 0.04 g of hydroquinone were added to a four-necked flask equipped with a stirrer, thermometer, water separator and condenser; the temperature was raised to 115 °C under nitrogen protection and the reaction was carried out for 5 hours until the acid value dropped to below 5 mg KOH / g; after cooling, the mixture was washed with 5% sodium carbonate solution and washed with water until neutral; excess hydroxyethyl acrylate was removed by vacuum distillation to obtain RAE.
[0054] (2) Synthesis of Flexible Rosin-g-BP: The above-synthesized RAE, 1.0 g 4-acryloyloxybenzophenone, and 2.25 g polyethylene glycol methyl ether acrylate (molecular weight 500) were dissolved in 50 mL of anhydrous THF. 0.2 g AIBN was added, and after purging with nitrogen for 30 minutes to remove oxygen, the mixture was reacted in an oil bath at 68 °C for 10 hours. The reaction solution was added dropwise to 500 mL of cold n-hexane to precipitate the solid. The solid was filtered, washed twice with n-hexane, and dried under vacuum at 40 °C to constant weight to obtain a pale yellow viscous solid, Flexible Rosin-g-BP.
[0055] (3) Preparation of prepolymer coating: Under light-protected conditions, add 75g of refined raw lacquer, the generated Flexible Rosin-g-BP, 11.26g of TMPTA, 0.62g of BYK-333 leveling agent and 0.5g of BYK-055 defoamer to the stirrer, stir at 400 r / min for 30 minutes, and control the temperature at 20℃.
[0056] (4) UV pre-irradiation: The mixture was placed in a water bath at 18°C and irradiated for 40 seconds with a 365nm low-pressure mercury lamp and a light intensity of 20 mW / cm². The viscosity of the system increased from 25 seconds (Ford-4 cup) to 42 seconds. Irradiation was stopped immediately to obtain the hybrid prepolymer coating.
[0057] (5) Post-processing and storage: Transfer the hybrid prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a low-temperature environment of 3°C away from light.
[0058] Example 4:
[0059] (1) Synthesis of RAE: 7.0 g of rosin acid, 2.5 g of hydroxyethyl acrylate, 0.2 g of p-toluenesulfonic acid and 0.04 g of hydroquinone were added to a four-necked flask equipped with a stirrer, thermometer, water separator and condenser; the temperature was raised to 115 °C under nitrogen protection and the reaction was carried out for 5 hours until the acid value dropped to below 5 mg KOH / g; after cooling, the mixture was washed with 5% sodium carbonate solution and washed with water until neutral; excess hydroxyethyl acrylate was removed by vacuum distillation to obtain RAE.
[0060] (2) Synthesis of Flexible Rosin-g-BP: The above-synthesized RAE, 1.56 g of 4-acryloyloxybenzophenone, and 1.5 g of polyethylene glycol methyl ether acrylate (molecular weight 500) were dissolved in 50 mL of anhydrous THF. 0.3 g of AIBN was added, and after purging with nitrogen for 30 minutes to remove oxygen, the mixture was reacted in an oil bath at 68 °C for 10 hours. The reaction solution was added dropwise to 500 mL of cold n-hexane to precipitate the solid. The solid was filtered, washed twice with n-hexane, and dried under vacuum at 40 °C to constant weight to obtain a pale yellow viscous solid, Flexible Rosin-g-BP.
[0061] (3) Preparation of prepolymer coating: Under light-protected conditions, add 77.5g of refined raw lacquer, the generated Flexible Rosin-g-BP, 9.0g of TMPTA, 0.2g of BYK-333 leveling agent, and 0.2g of BYK-055 defoamer to the mixer, stir at 400 r / min for 30 minutes, and control the temperature at 20℃.
[0062] (4) UV pre-irradiation: The mixture was placed in a water bath at 18°C and irradiated for 40 seconds with a 365nm low-pressure mercury lamp and a light intensity of 20 mW / cm². The viscosity of the system increased from 25 seconds (Ford-4 cup) to 42 seconds. Irradiation was stopped immediately to obtain the hybrid prepolymer coating.
[0063] (5) Post-processing and storage: Transfer the hybrid prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a low-temperature environment of 3°C away from light.
[0064] Example 5:
[0065] (1) Synthesis of RAE: In a four-necked flask equipped with a stirrer, thermometer, water separator and condenser, add 4.0 g rosin acid, 2.0 g hydroxyethyl acrylate, 0.2 g p-toluenesulfonic acid and 0.05 g hydroquinone; under nitrogen protection, heat to 115 °C and react for 5 hours until the acid value drops below 5 mg KOH / g; after cooling, wash with 5% sodium carbonate solution, wash with water until neutral, and remove excess hydroxyethyl acrylate by vacuum distillation to obtain RAE.
[0066] (2) Synthesis of Flexible Rosin-g-BP: The above-synthesized RAE, 2.0 g of 4-acryloyloxybenzophenone, and 2.65 g of polyethylene glycol methyl ether acrylate (molecular weight 500) were dissolved in 50 mL of anhydrous THF. 0.3 g of AIBN was added, and after purging with nitrogen for 30 minutes to remove oxygen, the mixture was reacted in an oil bath at 68 °C for 10 hours. The reaction solution was added dropwise to 500 mL of cold n-hexane to precipitate the solid. The solid was filtered, washed twice with n-hexane, and dried under vacuum at 40 °C to constant weight to obtain a pale yellow viscous solid, Flexible Rosin-g-BP.
[0067] (3) Preparation of prepolymer coating: Under light-protected conditions, add 80g of refined raw lacquer, the generated Flexible Rosin-g-BP, 8.0g of TMPTA, 0.3g of BYK-333 leveling agent, and 0.5g of BYK-055 defoamer to a mixer, stir at 400 r / min for 30 minutes, and control the temperature at 20℃.
[0068] (4) UV pre-irradiation: The mixture was placed in a water bath at 18°C and irradiated for 40 seconds with a 365nm low-pressure mercury lamp and a light intensity of 20 mW / cm². The viscosity of the system increased from 25 seconds (Ford-4 cup) to 42 seconds. Irradiation was stopped immediately to obtain the hybrid prepolymer coating.
[0069] (5) Post-processing and storage: Transfer the hybrid prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a low-temperature environment of 3°C away from light.
[0070] Example 6:
[0071] This embodiment provides a method for using the UV-curable raw lacquer hybrid prepolymer coating prepared by any one of Examples 1-5: The UV-curable raw lacquer hybrid prepolymer coating prepared by any one of Examples 1-5 is applied to the surface of a wood substrate by brushing, with the coating thickness controlled at 30 μm. It is then cured using a high-pressure mercury lamp (365 nm) with a light intensity of 80 mW / cm² and a curing time of 60 seconds, thereby forming a high-performance UV-curable raw lacquer hybrid prepolymer coating.
[0072] Example 7: Similar to Example 6, the difference is that the UV-curable raw lacquer hybrid prepolymer coating is applied to the surface of the metal substrate by spraying, with the coating thickness controlled at 20μm. It is cured by LED-UV lamp (395 nm) with a light intensity of 100mW / cm² and a curing time of 30 seconds, thus forming a high-performance UV-curable raw lacquer hybrid prepolymer coating.
[0073] Example 8: Similar to Example 6, except that the UV-curable raw lacquer hybrid prepolymer coating is applied to the surface of a plastic substrate by spray coating, with the coating thickness controlled at 40μm. It is cured by a high-pressure mercury lamp (365 nm) with a light intensity of 50 mW / cm² and a curing time of 90 seconds, thus forming a high-performance UV-curable raw lacquer hybrid prepolymer coating.
[0074] Performance testing:
[0075] The comprehensive performance of the UV-cured raw lacquer hybrid prepolymer coatings prepared in Examples 1-5 of this invention, respectively, through the method described in Example 6, was evaluated according to the following national standards and corresponding test methods: Pencil hardness was measured using a Zhonghua brand pencil and a QHQ-A type pencil hardness tester according to GB / T 6739–2006 "Determination of Hardness of Paints and Varnishes by Pencil Method"; Adhesion was rated using a BYK-5820 cross-cut tester (1 mm blade spacing) combined with the tape peeling method according to GB / T 9286–1998 "Cross-cut Test of Paints and Varnishes"; Abrasion resistance was measured using a Taber 5135 abrasion tester under the conditions of a CS-10 rubber abrasive wheel, 1000 g load, and 500 revolutions, according to GB / T 1768–2006 "Determination of Abrasion Resistance of Paints and Varnishes"; Gloss was measured according to GB / T According to GB / T 9754–2007 "Determination of 20°, 60° and 85° Specular Gloss of Paint Films without Metallic Pigments", a 60° incident angle was used, and the gloss was measured using a KGZ-60D gloss meter. Water resistance was determined according to GB / T 1733–1993 "Determination of Water Resistance of Paint Films", where samples were immersed in distilled water for 24 hours, and blistering, discoloration, and loss of gloss were observed. Flexibility was determined according to GB / T 1731–1993 "Determination of Flexibility of Paint Films", using a QTY-4 paint film flexibility tester. Test panels were bent with cylindrical shafts of different diameters (1–5 mm), and the minimum shaft diameter without cracks was recorded. Acid and alkali resistance were determined according to GB / T 9274–1988 "Determination of Resistance to Liquid Media of Paints and Varnishes", where 5% H2SO4 and 5% NaOH solutions were applied to the paint film surface, covered with a glass dish, and allowed to stand for 24 hours before evaluating the appearance changes. Antistatic properties were determined according to GB / T According to GB / T 1410–2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", the surface resistivity (Ω) of the coating was measured using a ZC-90G high-resistivity meter at a temperature of 23±2°C and a relative humidity of 50±5%. Corrosion resistance was tested according to GB / T 1771–2007 "Determination of Neutral Salt Spray Resistance of Paints and Varnishes". Samples were placed in a YWX / Q-150 salt spray chamber for neutral salt spray (NSS) testing, and the time (h) for the appearance of red rust or blistering was recorded. The comparative example for this experiment was a commercially available ordinary UV varnish. The test results are shown in Tables 1 and 2.
[0076] Table 1 shows the test results:
[0077] Paint type hardness Adhesion abrasion resistance gloss Water resistance Example 1 2H Level 0 Level 1 Highlights No abnormalities Example 2 3H Level 1 Level 1 Highlights No abnormalities Example 3 2H Level 0 Level 1 Highlights No abnormalities Example 4 2H Level 0 Level 1 Highlights No abnormalities Example 5 3H Level 1 Level 1 Highlights No abnormalities Comparative Example H Level 2 Level 2 Zhongguang obvious abnormality
[0078] Table 2 shows the test results:
[0079] Paint type flexibility Acid and alkali resistance Antistatic properties Corrosion resistance Example 1 excellent No change Antistatic Level 0 Example 2 excellent No change Antistatic Level 0 Example 3 excellent No change Antistatic Level 0 Example 4 excellent No change Antistatic Level 0 Example 5 excellent slight changes Antistatic Level 1 Comparative Example good obvious damage insulator Level 2
[0080] From the test results in Tables 1 and 2, we can conclude that:
[0081] 1. Overall performance is superior to commercially available ordinary UV clear coats (comparative example):
[0082] Compared with traditional commercially available UV varnishes, the coatings prepared by this invention (Examples 1-5) exhibit significant advantages in several key performance indicators:
[0083] Achieving both high hardness and strong adhesion: The coatings prepared in Examples 1-5, when applied to the substrate, generally exhibited a pencil hardness of 2H to 3H (higher than the H of the comparative example), and an adhesion grade of 0 or 1 (better than the 2 of the comparative example). This demonstrates that the coatings maintain high hardness while adhering extremely firmly to the substrate.
[0084] Excellent wear resistance and weather resistance: The coatings prepared in Examples 1-5, when applied to the substrate, all exhibited a wear resistance of Grade 1 and showed no abnormalities in water resistance; while the comparative examples showed a wear resistance of Grade 2 and significant abnormalities in water resistance. This indicates that the coating structure of the present invention is more dense and stable.
[0085] Significantly improved flexibility: The coatings prepared in Examples 1-5, after being applied to the substrate, all exhibited "excellent" flexibility, while the comparative examples were only rated "good." This verifies that the patented method of introducing flexible segments (polyethylene glycol methyl ether acrylate) and forming an interpenetrating network structure successfully overcomes the "hard and brittle" defects of pure raw paint and conventional UV coatings.
[0086] High chemical resistance: The coatings prepared in Examples 1-5, when applied to the substrate, mostly showed "no change" or only "slight change" in acid and alkali resistance tests, while the comparative examples showed "significant damage". This indicates that the rosin skeleton and lacquer network together provide excellent chemical barrier properties.
[0087] Outstanding corrosion resistance: The coatings prepared in Examples 1-5, when applied to the substrate, achieve a corrosion resistance of level 0 or 1, which is far superior to level 2 of the comparative example, proving that the coatings of the present invention can more effectively block corrosive media.
[0088] 2. It achieves a balance between functionality and environmental friendliness:
[0089] Antistatic function: Examples 1-4 all exhibited "antistatic" properties, as did Example 5, while the comparative example was an "insulator". This demonstrates that the coating system of the present invention not only provides protection but also endows the coating with additional antistatic functionality through structural design, expanding its application in areas surrounding electronic equipment or in locations with high dust protection requirements.
[0090] 3. Stability of formulation and process:
[0091] High performance repeatability: Although the raw material ratios were adjusted in the five embodiments, the core properties of the final coating (such as abrasion resistance, gloss, and flexibility) remained highly consistent. This indicates that the invention has a wide formulation window, a stable and reliable preparation process, and good prospects for industrial production.
[0092] 4. Boundary hints for Example 5:
[0093] In the five embodiments, Example 5 used the least amount of rosin acid (4.0 parts), the most amount of raw lacquer (80 parts), and the least amount of TMPTA (crosslinking agent) (8.0 parts). The test results showed a "slight change" in acid resistance and a decrease in corrosion resistance to "Level 1".
[0094] Conclusion: This reveals that the contents of the rosin skeleton, flexible monomers, and crosslinking agents need to be maintained at a balance to ensure optimal performance. Too little rigid skeleton and crosslinking density may lead to a slight decrease in chemical resistance, but even so, its overall performance is still far superior to the comparative example.
[0095] Summarize:
[0096] The data in Tables 1 and 2 strongly support the beneficial effects described in the invention content section of the patent: Through a molecular design that combines rigidity and flexibility and a pre-grafting process, the present invention has successfully prepared a green UV-curable coating that combines high hardness, high flexibility, strong adhesion, excellent chemical resistance and antistatic function. Its comprehensive performance significantly surpasses that of traditional commercially available products, and solves the long-standing technical bottleneck in the field of raw lacquer modification.
[0097] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection of this invention is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.
Claims
1. A UV-curable raw lacquer hybrid prepolymer coating, characterized in that, It contains the following components: Rosin acid, hydroxyethyl acrylate, p-toluenesulfonic acid, polymerization inhibitor, 4-acryloyloxybenzophenone, polyethylene glycol methyl ether acrylate, azobisisobutyronitrile, refined raw lacquer, crosslinking agent, leveling agent, and defoamer.
2. The UV-curable raw lacquer hybrid prepolymer coating according to claim 1, characterized in that, The coating is prepared from raw materials comprising the following parts by weight: 4-8 parts rosin acid, 2-4 parts hydroxyethyl acrylate, 0.05-0.2 parts p-toluenesulfonic acid, 0.01-0.05 parts polymerization inhibitor, 1-2 parts 4-acryloyloxybenzophenone, 1.5-3 parts polyethylene glycol methyl ether acrylate, 0.1-0.3 parts azobisisobutyronitrile, 70-80 parts refined raw lacquer, 8-12 parts crosslinking agent, 0.2-0.8 parts leveling agent, 0.2-0.8 parts defoamer.
3. The UV-curable raw lacquer hybrid prepolymer coating according to claim 2, characterized in that, The molecular weight of the polyethylene glycol methyl ether acrylate is 400-600; the polymerization inhibitor is hydroquinone; the crosslinking agent is trimethylolpropane triacrylate; the azobisisobutyronitrile is recrystallized; the leveling agent is polyether-modified polysiloxane; and the defoamer is a non-silicone polymer defoamer.
4. A method for preparing a UV-curable raw lacquer hybrid prepolymer coating as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Synthesis of rosin acid ethyl acrylate (RAE): Rosin acid, hydroxyethyl acrylate, p-toluenesulfonic acid and polymerization inhibitor are mixed and reacted under a protective atmosphere. After post-treatment, RAE is obtained. (2) Synthesis of flexible rosin-based macromolecular photoinitiator Flexible Rosin-g-BP: The RAE, 4-acryloyloxybenzophenone and polyethylene glycol methyl ether acrylate obtained in step (1) were dissolved in anhydrous tetrahydrofuran, and azobisisobutyronitrile was added. The reaction was carried out under a protective atmosphere, and after precipitation and drying, Flexible Rosin-g-BP was obtained. (3) Premixing: Under light-protected conditions, the refined raw lacquer, the Flexible Rosin-g-BP obtained in step (2), the crosslinking agent, the leveling agent and the defoamer are mixed evenly to obtain a mixture; (4) UV pre-irradiation grafting: The mixture obtained in step (3) is subjected to UV pre-irradiation at low temperature until the viscosity of the system increases but does not reach the gel point, thus obtaining a raw lacquer-based UV-curable hybrid prepolymer coating. (5) Post-processing and storage: Store the prepolymer coating obtained in step (4) under light-proof and low-temperature conditions.
5. The preparation method according to claim 4, characterized in that, Step (1) includes: Rosin acid, hydroxyethyl acrylate, p-toluenesulfonic acid, and hydroquinone were added to a four-necked flask and reacted at 110-120°C for 4-6 hours under nitrogen protection. The reaction progress was tracked by measuring the acid value. After the reaction was completed, the mixture was cooled, washed with dilute alkali solution, washed with water until neutral, and excess hydroxyethyl acrylate was removed by vacuum distillation to obtain a pale yellow viscous liquid, RAE.
6. The preparation method according to claim 4, characterized in that, Step (2) includes: RAE, 4-acryloyloxybenzophenone, and polyethylene glycol methyl ether acrylate were dissolved in anhydrous tetrahydrofuran, and azobisisobutyronitrile was added. After purging with nitrogen for 30 minutes to remove oxygen, the mixture was stirred in an oil bath at 65-70°C for 8-12 hours. After the reaction was completed, the solution was added dropwise to cold n-hexane to precipitate the precipitate. The precipitate was filtered, washed, and dried under vacuum to obtain a pale yellow Flexible Rosin-g-BP.
7. The preparation method according to claim 4, characterized in that, Step (3) includes: Under light-protected conditions, refined raw lacquer, Flexible Rosin-g-BP, trimethylolpropane triacrylate, polyether-modified polysiloxane, and non-silicone polymer defoamer are mixed evenly in a stirrer at a low speed of 300-500 r / min, with the temperature controlled below 25℃.
8. The preparation method according to claim 4, characterized in that, Step (4) includes: The mixture is placed in a low-temperature water bath at 15~20℃ and irradiated for 30~45 seconds with a light intensity of 10~30 mW / cm² using a low-pressure mercury lamp or medium-pressure mercury lamp with a main wavelength of 365nm and a filter, until the viscosity of the system increases significantly but does not reach the gel point, thus obtaining a raw lacquer-based UV-curable hybrid prepolymer. Step (5) includes: Transfer the prepolymer coating to an opaque container, fill it with nitrogen for protection, and store it in a low-temperature environment of 0~5℃ away from light.
9. A method of using a UV-curable raw lacquer hybrid prepolymer coating as described in any one of claims 1-3, characterized in that, The prepolymer coating is applied to the surface of the substrate to form a film, and then cured with UV light to form a coating layer.
10. The method of use according to claim 9, characterized in that, The coating thickness is 20~40 μm; the UV curing light intensity is 50~100 mW / cm², and the curing time is 30~90 seconds; the UV light source is a high-pressure mercury lamp or an LED-UV lamp, with a wavelength of 365 nm or 395 nm.