Dual-curing polyurethane acrylate resin and preparation method thereof

Abstract

The invention relates to the technical field of polyurethane acrylate, and particularly discloses dual-curing polyurethane acrylate resin and a preparation method thereof. Wherein the dual-curing polyurethane acrylate resin is prepared from the following raw materials: polyester polyol, polyether polyol, diisocyanate, hydroxyl acrylate, a chain extender, a photoinitiator, cardanol glycidyl ether, a polymerization inhibitor and modified nanoparticles. Wherein the citric acid and the polyethyleneimine are adopted to carry out synergistic modification on the nano particles, the dispersion stability of the nano particles is improved, so that the mechanical property of the resin is improved, the cardanol glycidyl ether and the photoinitiator generate a synergistic effect, and the resin can be quickly shaped through photocuring promoted by the photoinitiator; the cardanol glycidyl ether participates in the subsequent thermocuring reaction, so that the curing effect is improved, and the adhesive force between the film layer and the base material is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane acrylate, in particular to a double-curing polyurethane acrylate resin and a preparation method thereof. BACKGROUND

[0002] The polyurethane acrylate resin is a functional material combining the excellent mechanical properties of polyurethane and the high reactivity of acrylate. Its molecular structure consists of isocyanate hard segments and polyol soft segments. By adjusting the ratio of soft and hard segments, the mechanical properties, weather resistance, and processability of the resin can be adjusted. Different formulations can be designed to meet different application conditions. Therefore, the polyurethane acrylate resin has wide applications in coatings, adhesives, inks, and other fields, especially in scenarios requiring rapid curing, where UV (ultraviolet) curing or thermal curing technology is often used.

[0003] Thermal curing technology mainly uses heat energy to promote the formation of chemical bonds between molecules to achieve material hardening. UV curing technology, on the other hand, uses the energy of ultraviolet light to excite the photoinitiator in the resin, initiate polymerization, and achieve rapid curing. These two technologies play important roles in their respective applicable scenarios.

[0004] However, there are obvious limitations in using a single curing method. Thermal curing requires a large amount of energy to maintain a high-temperature environment, and the curing process is relatively slow, resulting in low production efficiency. UV curing often results in incomplete and uneven curing when dealing with oxygen inhibition, insufficient light penetration in thick coatings, and difficulty in penetrating light in shadow areas, leading to insufficient adhesion between the film layer and the substrate, affecting product quality and service life. SUMMARY

[0005] To fully utilize the advantages of light curing and thermal curing mechanisms and ensure that the material can be fully and uniformly cured in complex environments, thereby ensuring the stability and reliability of the resin material properties, the present application provides a double-curing polyurethane acrylate resin and a preparation method thereof.

[0006] In a first aspect, the present application provides a double-curing polyurethane acrylate resin, which is prepared from the following raw materials by weight: polyester polyol 20-25 parts, polyether polyol 20-30 parts, diisocyanate 28-32 parts, hydroxy acrylate 12-16 parts, chain extender 3-7 parts, photoinitiator 1-3 parts, cashew phenol glycidyl ether 2-4 parts, polymerization inhibitor 0.3-0.7 parts, modified nanoparticles 10-14 parts; The preparation raw material of the modified nanoparticles comprises nanoparticles, citric acid and polyethylene imine, and the weight ratio of the nanoparticles, the citric acid and the polyethylene imine is 1:(0.8-1.2):(0.5-0.7).

[0007] By adopting the technical scheme, the polyester polyol and the polyether polyol are used as the soft segment component, which helps to adjust the flexibility and processing performance of the resin, and the diisocyanate reacts with the polyester polyol, the polyether polyol and the chain extender to form the hard segment of the polyurethane structure, which gives the resin good mechanical properties. In the application, the nanoparticles are modified by citric acid and polyethylene imine. The citric acid contains carboxyl groups, which can react with the hydroxyl groups on the surface of the nanoparticles to introduce carboxyl functional groups on the surface of the nanoparticles. The polyethylene imine is rich in amino groups, which can react with the carboxyl groups introduced by the citric acid to be grafted onto the surface of the nanoparticles, so that the nanoparticles are uniformly dispersed in the resin matrix, the spontaneous spreading and collapse of the nanoparticles are reduced, and the dispersion stability of the nanoparticles is improved, thereby improving the mechanical properties, processing performance and the like of the resin.

[0008] In addition, the photoinitiator has higher reactivity and can more effectively promote the polymerization reaction of the resin, thereby accelerating the curing process of the film layer. Cashew phenol glycidyl ether has multiple advantages as an active diluent. On the one hand, cashew phenol glycidyl ether can reduce the viscosity of the resin, improve the construction performance, help the film layer to be more uniformly distributed on the substrate, and reduce the generation of bubbles and defects; on the other hand, cashew phenol glycidyl ether and the photoinitiator produce a synergistic effect. The photopolymerization promoted by the photoinitiator can first make the resin quickly shape, and the subsequent thermal curing reaction of cashew phenol glycidyl ether is involved, thereby improving the curing effect and enhancing the adhesion between the film layer and the substrate.

[0009] Preferably, the preparation method of the modified nanoparticles is as follows: (1) dispersing the nanoparticles in a solvent, ultrasonic dispersion for 40-60 min, adjusting the pH of the solution to 3-5, adding citric acid, stirring at 60-80℃ for 6-8h, after the reaction is completed, filtering, washing and drying to obtain citric acid modified nanoparticles; (2) dispersing the polyethylene imine in a solvent, ultrasonic dispersion for 40-60 min to obtain a polyethylene imine solution, dispersing the citric acid modified nanoparticles in a solvent, ultrasonic dispersion for 40-60 min to obtain a suspension, slowly adding the polyethylene imine solution into the suspension, reacting at room temperature for 10-12h, filtering, washing and drying to obtain the modified nanoparticles.

[0010] By adopting the technical scheme, the carboxyl groups in the citric acid molecules can be combined with the hydroxyl groups on the surface of the nanoparticles, so that the surface of the nanoparticles is covered by the citric acid and carries carboxyl and hydroxyl groups, the active groups on the surface of the nanoparticles are increased, the binding force between the nanoparticles and the polyethylene imine is enhanced, the polyethylene imine is further modified, the carboxyl and hydroxyl groups in the citric acid molecules can be combined with the amino groups in the polyethylene imine molecules, the polyethylene imine is grafted to the surface of the nanoparticles, and the dispersibility of the nanoparticles in the resin system is improved, so that the mechanical properties of the resin are improved.

[0011] Preferably, the nanoparticles are selected from one or more of silicon dioxide, aluminum oxide, zirconium oxide, quartz powder, talc powder, mica powder, kaolin, and silicon powder.

[0012] By adopting the technical scheme, the nanoparticles are added, the mechanical properties, weather resistance, processability and other properties of the resin are adjusted by using the characteristics of the nanoparticles.

[0013] Preferably, the hydroxy acrylate is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, and pentaerythritol triacrylate.

[0014] By adopting the technical scheme, the hydroxy acrylate is used as a raw material to prepare a dual-cured polyurethane acrylate resin, and the high reactivity of the hydroxy acrylate is used to cooperate with other ingredients to effectively make up for the problems of low curing efficiency, incomplete and uneven curing, and poor adhesion of the film layer to the substrate. Specifically, the double bond residual polymerization reaction in the molecular structure of the hydroxy acrylate helps the dual-cured polyurethane acrylate resin to cross-link during the ultraviolet light curing process, accelerates the curing speed, and improves the curing efficiency. The hydroxyl groups in the molecular structure can react with diisocyanate, which helps to form urethane bonds, thereby constructing the molecular skeleton of the resin and enhancing the mechanical properties and stability of the resin.

[0015] Preferably, the photoinitiator is one or more of alpha-hydroxy ketones, phenylacetone and its derivatives, and acyl phosphine oxide.

[0016] By adopting the technical scheme, the photoinitiator generates free radicals under the irradiation of ultraviolet light, initiates the polymerization of double bonds to form a cross-linked network, makes the film layer quickly surface dry and set, reduces the deformation caused by fluidity in the subsequent curing stage, and at the same time forms a synergistic effect with the subsequent thermal curing, so that the deep layer is cured, and the material is completely cured to achieve the optimization of performance.

[0017] Preferably, the polymerization inhibitor is one or more of p-hydroxyanisole, hydroquinone, and p-benzoquinone.

[0018] By adopting the technical scheme, the addition of the polymerization inhibitor helps to inhibit the free radical polymerization reaction, prevent the resin from prematurely polymerizing during preparation, and ensure the stability and controllability of the resin preparation process.

[0019] Preferably, the polyester polyol is selected from one or more of polyethylene glycol adipate diol, polyneopentyl glycol adipate, polycaprolactone, and polycarbonate diol; and the polyether polyol is selected from one or more of polypropylene oxide diol and polytetrahydrofuran ether diol.

[0020] By adopting the technical scheme, the polyester polyol and the polyether polyol are used to adjust the soft / hard segment ratio of the resin, so as to adjust the mechanical properties, weather resistance, and processability of the resin.

[0021] Preferably, the diisocyanate is selected from one or more of dicyclohexyl methane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

[0022] By adopting the technical scheme, the use of the aliphatic isocyanate has better weather resistance and anti-yellowing property, so that the resin is less likely to discolor and age during long-term use.

[0023] Preferably, the chain extender is selected from one or more of ethylenediamine, neopentyl glycol, sorbitol, and diethanolamine.

[0024] By adopting the technical scheme, the addition of the chain extender helps to adjust the length and structure of the molecular chain of the resin, so as to adjust the mechanical properties, weather resistance, and processability of the resin.

[0025] In a second aspect, the application provides a preparation method of the dual-curing polyurethane acrylate resin, which adopts the following technical scheme: The preparation method of the dual-curing polyurethane acrylate resin comprises the following steps: S1: The raw materials are weighed according to the component allocation ratio, the polyester polyol and the polyether polyol are mixed, nitrogen is introduced, and stirring is performed at 120-130℃ for 1-2h; the temperature is lowered to 60-70℃, the diisocyanate, the chain extender, and the acetone are added, and reaction is performed for 1-2h to obtain a polyurethane prepolymer; S2: The polyurethane prepolymer, the polymerization inhibitor, and the catalyst are uniformly mixed, and the hydroxy acrylate is added dropwise under stirring at 60-65℃ within 1.5-2h; after the dropwise addition is completed, the reaction temperature is maintained, and reaction is continued for 0.5-1h; the temperature is raised to 70-75℃, and stirring reaction is performed for 0.5-1h to remove the acetone, thereby obtaining a polyurethane acrylate prepolymer; S3: mixing the polyurethane acrylate prepolymer, the photoinitiator, the cardanol glycidyl ether and the modified nanoparticles uniformly, ultrasonic dispersion for 30-40 min to obtain a dual-curing polyurethane acrylate resin, and store at low temperature in the dark.

[0026] Preferably, the catalyst is an organic tin catalyst.

[0027] By adopting the above technical solution, the preparation method makes the polyurethane acrylate resin have a dual-curing property, overcomes the problems of high energy consumption and low efficiency of single thermal curing, and the problems of incomplete and uneven curing of single UV curing, resulting in poor adhesion of the film layer to the substrate. The modified nanoparticles are added to the resin system, which can enhance the comprehensive performance of the resin. Since the nanoparticles have a large specific surface area and a unique surface effect, they can be better compatible with the resin matrix after modification, effectively improve the mechanical properties of the resin, and improve the strength and toughness of the resin, so that the resin maintains stable performance under different environmental conditions, and at the same time, helps to improve the processing performance of the resin.

[0028] The present application has the following beneficial effects: The present application uses polyester polyol and polyether polyol as soft segment components, which helps to adjust the flexibility and processing performance of the resin. The diisocyanate reacts with the polyester polyol, the polyether polyol and the chain extender to form a hard segment of the polyurethane structure, which gives the resin good mechanical properties. In the present application, the nanoparticles are modified by citric acid and polyethyleneimine. Citric acid contains carboxyl groups, which can esterify with the hydroxyl groups on the surface of the nanoparticles to introduce carboxyl functional groups on the surface of the nanoparticles. Polyethyleneimine is rich in amino groups, which can react with the carboxyl groups introduced by citric acid to graft onto the surface of the nanoparticles, making them uniformly dispersed in the resin matrix, reducing the spontaneous spreading and collapse of the nanoparticles, and improving the dispersion stability of the nanoparticles, thereby improving the mechanical properties, processing performance, etc. of the resin.

[0029] In addition, the photoinitiator has higher reactivity and can more effectively promote the polymerization reaction of the resin, thereby accelerating the curing process of the film layer. Cardanol glycidyl ether, as an active diluent, has multiple advantages. On the one hand, cardanol glycidyl ether can reduce the viscosity of the resin, improve the construction performance, and help the film layer to be more uniformly distributed on the substrate, reducing the generation of bubbles and defects; on the other hand, cardanol glycidyl ether and the photoinitiator produce a synergistic effect. The photoinitiator promotes the photocuring to make the resin quickly shape, and the cardanol glycidyl ether participates in the subsequent thermal curing reaction, thereby improving the curing effect and enhancing the adhesion between the film layer and the substrate. DETAILED DESCRIPTION

[0030] Preparation Example Preparation Example 1 Preparation of modified nanoparticles: (1) 100 g mica powder was dispersed in 250 mL deionized water, ultrasonic dispersion for 40 min, the solution pH was adjusted to 3, 80 g citric acid was added, and the reaction was stirred at 60°C for 6 h. After the reaction was completed, filtration, washing and drying were performed to obtain citric acid modified nanoparticles; (2) 50 g polyethyleneimine (Aerosol 9002-98-6) was dispersed in 100 mL deionized water, ultrasonic dispersion for 40 min to obtain a polyethyleneimine solution. The citric acid modified nanoparticles were dispersed in 250 mL deionized water, ultrasonic dispersion for 40 min to obtain a suspension. The polyethyleneimine solution was slowly added dropwise into the suspension, and the reaction was carried out at room temperature for 10 h. Filtration, washing and drying were performed to obtain modified nanoparticles.

[0031] Preparation Example 2 Preparation of modified nanoparticles: (1) 120 g silicon dioxide was dispersed in 250 mL deionized water, ultrasonic dispersion for 50 min, the solution pH was adjusted to 4, 120 g citric acid was added, and the reaction was stirred at 70°C for 7 h. After the reaction was completed, filtration, washing and drying were performed to obtain citric acid modified nanoparticles; (2) 72 g polyethyleneimine (Aerosol 9002-98-6) was dispersed in 120 mL deionized water, ultrasonic dispersion for 50 min to obtain a polyethyleneimine solution. The citric acid modified nanoparticles were dispersed in 250 mL deionized water, ultrasonic dispersion for 50 min to obtain a suspension. The polyethyleneimine solution was slowly added dropwise into the suspension, and the reaction was carried out at room temperature for 11 h. Filtration, washing and drying were performed to obtain modified nanoparticles.

[0032] Preparation Example 3 Preparation of modified nanoparticles: (1) 70 g aluminum oxide and 70 g zirconium oxide were dispersed in 250 mL deionized water, ultrasonic dispersion for 60 min, the solution pH was adjusted to 5, 168 g citric acid was added, and the reaction was stirred at 80°C for 8 h. After the reaction was completed, filtration, washing and drying were performed to obtain citric acid modified nanoparticles; (2) 98 g polyethyleneimine (Aerosol 9002-98-6) was dispersed in 150 mL deionized water, ultrasonic dispersion for 60 min to obtain a polyethyleneimine solution. The citric acid modified nanoparticles were dispersed in 250 mL deionized water, ultrasonic dispersion for 60 min to obtain a suspension. The polyethyleneimine solution was slowly added dropwise into the suspension, and the reaction was carried out at room temperature for 12 h. Filtration, washing and drying were performed to obtain modified nanoparticles.

[0033] Preparation Example 4 The difference between this preparation example and Preparation Example 2 is that an equal amount of silicon powder is used instead of silicon dioxide.

[0034] Preparation Example 5 The difference between the present preparation example and Preparation Example 2 is that no citric acid is added, i.e. the preparation method of the modified nanoparticles is as follows: 120 g of silica was dispersed in 250 mL of deionized water and ultrasonically dispersed for 50 min to obtain a suspension, 72 g of polyethyleneimine (Aldrich 9002-98-6) was dispersed in 120 mL of deionized water and ultrasonically dispersed for 50 min to obtain a polyethyleneimine solution, the polyethyleneimine solution was slowly added to the suspension, and reacted at room temperature for 11 h, then filtered, washed and dried to obtain the modified nanoparticles.

[0035] Preparation Example 6 The difference between the present preparation example and Preparation Example 2 is that no polyethyleneimine is added, i.e. the preparation method of the modified nanoparticles is as follows: 120 g of silica was dispersed in 250 mL of deionized water and ultrasonically dispersed for 50 min, the pH of the solution was adjusted to 4, 120 g of citric acid was added, and the reaction was stirred at 70°C for 7 h. After the reaction was completed, the modified nanoparticles were obtained by filtration, washing and drying. Example

[0036] Example 1 A dual-curing polyurethane acrylate resin, the raw materials for preparation include: 200 g of polyethylene glycol adipate diol (Polysciences 25212-06-0), 200 g of polypropylene oxide diol (Momentive 25322-69-4), 280 g of dicyclohexylmethane diisocyanate, 120 g of hydroxyethyl acrylate, 30 g of ethylenediamine, 10 g of 3-hydroxy-3-methyl-2-butanone, 20 g of cardanol glycidyl ether (Hongrun 171263-25-5), 3 g of hydroquinone, and 100 g of modified nanoparticles (prepared in Preparation Example 1).

[0037] The preparation method of the dual-curing polyurethane acrylate resin of the present example includes the following steps: S1: The raw materials were weighed according to the components, the polyethylene glycol adipate diol and the polypropylene oxide diol were mixed, nitrogen was introduced, and the reaction was stirred at 120°C for 1 h. The temperature was lowered to 60°C, and dicyclohexylmethane diisocyanate, ethylenediamine and acetone were added, and the reaction was carried out for 1 h to obtain a polyurethane prepolymer; S2: The polyurethane prepolymer, hydroquinone and 1.5 g of dibutyltin dilaurate were mixed uniformly, and the hydroxyethyl acrylate was added dropwise under stirring at 60°C within 1.5 h. After the dropwise addition was completed, the reaction temperature was maintained, and the reaction was continued for 0.5 h. The temperature was raised to 70°C, and the reaction was stirred for 1 h to remove the acetone, thereby obtaining a polyurethane acrylate prepolymer; S3: The polyurethane acrylate prepolymer, 3-hydroxy-3-methyl-2-butanone, cardanol glycidyl ether, modified nanoparticles are mixed uniformly, ultrasonic dispersion for 30 min, to obtain a dual-curing polyurethane acrylate resin, low temperature storage in the dark.

[0038] Example 2 A dual-curing polyurethane acrylate resin, the preparation raw materials include: 230g polyneopentylene adipate (Xiyuhong 27925-07-1), 250g polytetrahydrofuran glycol (Deyi 25190-06-1), 300g isophorone diisocyanate, 140g hydroxypropyl acrylate, 50g sorbitol, 20g dimethoxyphenyl phenylacetone, 30g cardanol glycidyl ether (Hongrun 171263-25-5), 5g p-hydroxyanisole, 120g modified nanoparticles (prepared in Preparation Example 2).

[0039] The preparation method of the dual-curing polyurethane acrylate resin of the present embodiment includes the following steps: S1: The raw materials are weighed according to the components, polyneopentylene adipate and polytetrahydrofuran glycol are mixed, nitrogen is introduced, and stirring is carried out at 125℃ for 1.5h, the temperature is lowered to 65℃, isophorone diisocyanate, sorbitol and acetone are added, and reaction is carried out for 1.5h to obtain a polyurethane prepolymer; S2: The polyurethane prepolymer, p-hydroxyanisole and 2g dibutyltin dilaurate are mixed uniformly, hydroxypropyl acrylate is added dropwise under stirring at 65℃ within 2h, after the dropwise addition is completed, the reaction temperature is maintained, and reaction is continued for 1h, the temperature is raised to 75℃, and stirring is carried out for 1h to remove acetone, and a polyurethane acrylate prepolymer is obtained; S3: The polyurethane acrylate prepolymer, dimethoxyphenyl phenylacetone, cardanol glycidyl ether and modified nanoparticles are mixed uniformly, ultrasonic dispersion is carried out for 35min to obtain a dual-curing polyurethane acrylate resin, which is stored in the dark at low temperature.

[0040] Example 3 A dual-curing polyurethane acrylate resin, the preparation raw materials include: 250g polycarbonate diol (Lanbai 29862-10-0), 300g polytetrahydrofuran glycol (Deyi 25190-06-1), 320g hexamethylene diisocyanate, 160g pentaerythritol triacrylate, 70g diethanolamine, 30g BAPO, 40g cardanol glycidyl ether (Hongrun 171263-25-5), 7g p-benzoquinone, 140g modified nanoparticles (prepared in Preparation Example 3).

[0041] The preparation method of the dual-curing polyurethane acrylate resin of the present embodiment includes the following steps: S1: Weigh the raw materials according to the components, mix polycarbonate diol and polytetrahydrofuran ether diol, introduce nitrogen gas, stir and react at 130°C for 2 hours, cool down to 70°C, add hexamethylene diisocyanate, diethanolamine and acetone, react for 2 hours to obtain polyurethane prepolymer; S2: Mix polyurethane prepolymer, p-benzoquinone, and 2.5g dibutyltin dilaurate evenly. Under stirring conditions at 65℃, add pentaerythritol triacrylate dropwise over 2 hours. After the addition is complete, maintain the reaction temperature and continue the reaction for 1 hour. Raise the temperature to 75℃ and stir for 1 hour to remove acetone and obtain polyurethane acrylate prepolymer. S3: Mix polyurethane acrylate prepolymer, BAPO, cashew phenol glycidyl ether, and modified nanoparticles evenly, and ultrasonically disperse for 40 min to obtain double-cured polyurethane acrylate resin, which should be stored in the dark at low temperature.

[0042] Example 4 The difference between this embodiment and Example 2 is that the modified nanoparticles prepared in Example 4 are used.

[0043] Example 5 The difference between this embodiment and Embodiment 2 is that an equal amount of hydroxypropyl methacrylate is used instead of hydroxypropyl acrylate.

[0044] Example 6 The difference between this embodiment and Embodiment 2 is that an equal amount of trimethylolpropane diacrylate is used instead of hydroxypropyl acrylate.

[0045] Comparative Example Comparative Example 1 A dual-curing polyurethane acrylate resin differs from Example 2 in that it uses the modified nanoparticles obtained in Preparation Example 5.

[0046] Comparative Example 2 A dual-curing polyurethane acrylate resin differs from Example 2 in that it uses the modified nanoparticles obtained in Preparation Example 6.

[0047] Comparative Example 3 A dual-curing polyurethane acrylate resin differs from Example 2 in that an equal amount of silica is used instead of modified nanoparticles.

[0048] Comparative Example 4 A dual-curing polyurethane acrylate resin, which differs from Example 2 in that no modified nanoparticles are added.

[0049] Comparative Example 5 A dual-curing polyurethane acrylate resin differs from Example 2 in that an equal amount of ethyl acrylate is used instead of hydroxypropyl acrylate.

[0050] Comparative Example 6 A dual-curing polyurethane acrylate resin, which is different from Example 2 in that an equal amount of cardanol is used instead of cardanol glycidyl ether.

[0051] Comparative Example 7 A dual-curing polyurethane acrylate resin, which is different from Example 2 in that no cardanol glycidyl ether is added.

[0052] Performance detection test The dual-curing polyurethane acrylate resins prepared in Examples 1-6 and Comparative Examples 1-7 are uniformly coated on a substrate, and after defoaming, they are placed in an ultraviolet light curing machine with an intensity of 600 mW / cm 2 Cured in an ultraviolet light curing machine, and after taking out, heat curing is carried out at 80-120°C.

[0053] 1. Drying time: according to the national standard GB / T 1728-2020, the surface drying time of the film layer is determined by the method of touch, and the real drying time of the film layer is determined by the method of knife.

[0054] 2. Adhesion test: according to the national standard GB / T 9286-2021, the adhesion of the coating is determined by the grid method.

[0055] 3. Mechanical property test: the tensile strength and elongation at break of the cured sample are tested by a universal electronic tensile testing machine (Shenzhen Sanechips, UTM4103X type), and each formula is tested 5 times, and the average value is taken, and the test results are recorded in Table 1.

[0056] Table 1 According to the comparison of Example 2 and Comparative Examples 1-2 and the data in Table 1, it can be seen that in Comparative Example 1, only polyethyleneimine is used to modify the nanoparticles, and in Comparative Example 2, only citric acid is used to modify the nanoparticles. These two modification methods cannot make the nanoparticles achieve good dispersion effect, and the resin has long drying time, the nanoparticles will settle and agglomerate, affecting the performance of the resin. The present application uses citric acid and polyethyleneimine to synergistically modify the nanoparticles, which makes the nanoparticles uniformly disperse in the resin matrix, reduces the spontaneous spreading and collapse of the nanoparticles, improves the dispersion stability of the nanoparticles, shortens the drying time, and improves the mechanical properties of the resin.

[0057] According to the comparison of example 2 and comparative example 3-4 and the data in table 1, it can be seen that: in comparative example 3, the silica is not modified, and due to the high surface energy of the silica, it is easy to agglomerate and affect the performance of the resin; in comparative example 4, no modified nanoparticles are added, which leads to a significant decrease in the mechanical properties of the resin film layer. In the present application, the nanoparticles are modified by citric acid and polyethyleneimine, which makes the nanoparticles uniformly dispersed in the resin matrix, reduces the spontaneous spreading and collapse of the nanoparticles, improves the dispersion stability of the nanoparticles, shortens the drying time, and improves the mechanical properties of the resin.

[0058] According to the comparison of example 2 and comparative example 5 and the data in table 1, it can be seen that: the molecular structure of ethyl acrylate does not contain hydroxyl groups, and its reactivity is relatively weak, and its binding force with the polyurethane prepolymer is not as good as that of hydroxy acrylate. In the present application, hydroxy acrylate is used to react with polyurethane prepolymer to prepare polyurethane acrylate with good tensile properties and adhesion.

[0059] According to the comparison of example 2 and comparative example 6-7 and the data in table 1, it can be seen that: the molecular structure of cardanol glycidyl ether contains epoxy groups, which eliminates radical interference, while retaining the flexibility and hydrophobicity of long-chain alkyl groups. Cardanol glycidyl ether does not interfere with free radical polymerization during the light curing stage, but undergoes ring-opening reaction during the thermal curing stage to form deep cross-linking, which solves the problem of curing the inner layer of thick coating or complex structure and improves the adhesion of the resin film layer.

[0060] The specific embodiment is only an explanation of the present application, and is not a limitation of the present application. Those skilled in the art can make modifications to the specific embodiment without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A dual-curing polyurethane acrylate resin, characterized in that, It is prepared from the following raw materials in parts by weight: Polyester polyol 20-25 parts, polyether polyol 20-30 parts, diisocyanate 28-32 parts, hydroxyl acrylate 12-16 parts, chain extender 3-7 parts, photoinitiator 1-3 parts, cashew phenol glycidyl ether 2-4 parts, polymerization inhibitor 0.3-0.7 parts, modified nanoparticles 10-14 parts; The raw materials for preparing the modified nanoparticles include nanoparticles, citric acid, and polyethyleneimine, wherein the weight ratio of the nanoparticles, citric acid, and polyethyleneimine is 1:(0.8-1.2):(0.5-0.7).

2. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The method for preparing the modified nanoparticles is as follows: (1) Disperse nanoparticles in a solvent, ultrasonically disperse for 40-60 min, adjust the pH of the solution to 3-5, add citric acid, stir and react at 60-80℃ for 6-8 h, after the reaction is completed, filter, wash and dry to obtain citric acid modified nanoparticles; (2) Disperse polyethyleneimine in a solvent and ultrasonically disperse for 40-60 min to obtain a polyethyleneimine solution. Disperse citric acid modified nanoparticles in a solvent and ultrasonically disperse for 40-60 min to obtain a suspension. Slowly add the polyethyleneimine solution to the suspension and react at room temperature for 10-12 h. Filter, wash and dry to obtain modified nanoparticles.

3. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The nanoparticles are selected from one or more of the following: silicon dioxide, alumina, zirconium oxide, quartz powder, talc powder, mica powder, kaolin, and silica powder.

4. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The hydroxy acrylate is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, trimethylolpropane diacrylate, and pentaerythritol triacrylate.

5. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The photoinitiator is one or more of α-hydroxy ketones, acetophenone and its derivatives, and acylphosphine oxides.

6. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The polymerization inhibitor is one or more of p-hydroxyanisole, hydroquinone, and p-benzoquinone.

7. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The polyester polyol is selected from one or more of polyethylene adipate diol, polypentyl adipate diol, polycaprolactone, and polycarbonate diol; the polyether polyol is selected from one or two of polypropylene glycol and polytetrahydrofuran ether diol.

8. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The diisocyanate is selected from one or more of dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

9. The dual-curing polyurethane acrylate resin according to claim 1, characterized in that, The chain extender is selected from one or more of ethylenediamine, neopentyl glycol, sorbitol, and diethanolamine.

10. A method for preparing a dual-curing polyurethane acrylate resin according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Weigh the raw materials according to the composition ratio, mix the polyester polyol and polyether polyol, introduce nitrogen gas, stir and react at 120-130℃ for 1-2 hours, cool down to 60-70℃, add diisocyanate, chain extender and acetone, react for 1-2 hours to obtain polyurethane prepolymer. S2: Mix the polyurethane prepolymer, polymerization inhibitor, and catalyst evenly. Under stirring conditions at 60-65℃, add hydroxyl acrylate dropwise over 1.5-2 hours. After the addition is complete, maintain the reaction temperature and continue the reaction for 0.5-1 hours. Raise the temperature to 70-75℃ and stir the reaction for 0.5-1 hours to remove acetone and obtain the polyurethane acrylate prepolymer. S3: Mix polyurethane acrylate prepolymer, photoinitiator, cashew phenol glycidyl ether, and modified nanoparticles evenly, and ultrasonically disperse for 30-40 minutes to obtain double-cured polyurethane acrylate resin, which should be stored in the dark at low temperature.

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