Self-repairing ultraviolet light-cured resin, preparation method and application thereof

Abstract

This invention belongs to the field of UV-curable resins, specifically relating to a self-healing UV-curable resin, its preparation method, and its applications. The preparation method includes the steps of: adding p-hydroxyanisole, glycidyl methacrylate, and 4-dimethylaminopyridine to an amino-terminated prepolymer and reacting, followed by separation to obtain the resin. The preparation method of the amino-terminated prepolymer includes adding an activator to a carboxyl-terminated prepolymer and reacting it, followed by adding a polyetheramine. The preparation method of the carboxyl-terminated prepolymer includes reacting a diol and an anhydride in a solvent. The invention provides corresponding products and their applications in the preparation of UV-curable coatings, UV-curable adhesives, and 3D printing consumables. Compared to existing technologies, the coating prepared by the method provided in this invention exhibits significant self-healing function and high elongation at break.

Description

Technical Field

[0001] This invention relates to a method for preparing a self-healing UV-curable resin and its application, belonging to the field of UV-curable resin technology. Background Technology

[0002] UV-curable resins are widely used in coatings, adhesives, 3D printing, and other fields due to their advantages such as fast curing speed, energy saving, environmental protection, and solvent-free emissions. However, traditional UV-curable resins are mostly highly cross-linked rigid networks, which are prone to cracking under external forces and cannot self-repair, limiting their application in scenarios with high damage resistance requirements.

[0003] Self-healing materials repair material damage by introducing dynamic chemical bonds (such as disulfide bonds, imine bonds, hydrogen bonds, and acylhydrazone bonds) to reconstruct molecular chains under external stimuli. Among these, disulfide bonds have high dynamic exchange activity and can break and recombine under mild heating conditions, making them ideal dynamic chemical bonds for constructing self-healing polymer materials.

[0004] For example, Chinese patent application CN120192509A discloses a UV-curable waterborne polyurethane acrylate resin, its preparation method, and its application. This method is based on the Schiff base reaction of disulfides to prepare a monomer with a tandem dynamic bond between a disulfide bond and an imine bond. This tandem dynamic bond monomer is introduced into the waterborne polyurethane acrylate resin as a functional chain extender. Compared to UV-cured resins with single dynamic bonds and simple mixed dynamic bonds, the tandem dynamic bond has a lower activation energy, thus endowing the UV-cured coating based on the tandem dynamic bond with superior self-healing properties. Research on introducing disulfide bonds into UV-curable resins has mostly focused on polyurethane acrylate systems, while reports on amide-type systems based on polyetheramines and acid anhydrides are relatively few. Although amide-type resins have better adhesion, they suffer from slow curing speed and low repair efficiency.

[0005] Therefore, how to provide a self-healing UV-curable resin based on an amide system, and improve the curing speed, repair efficiency, and mechanical properties of the UV-curable resin based on the amide system, is one of the technical problems that those skilled in the art hope to solve. Summary of the Invention

[0006] This invention addresses the problems of slow curing speed and low repair efficiency in amide-type photocurable resin systems based on polyetheramine and acid anhydride by providing a self-healing UV-curable resin, its preparation method, and its application.

[0007] Overcoming the slow curing of traditional anhydride-amide systems, this invention achieves rapid photocuring: Addressing the bottleneck of traditional anhydride-amide systems relying on thermal curing and being slow, this invention abandons the thermal ring-opening curing mechanism of anhydride groups. Instead, it uses glycidyl methacrylate to precisely functionalize the amino-terminated prepolymer, converting the terminal amino groups into highly reactive acrylate double bonds.

[0008] The present invention uses the above molecular design to change the crosslinking mechanism of the entire system, transforming it from slow thermal polymerization to rapid free radical polymerization initiated by ultraviolet light. The curing time is significantly shortened from hours in the traditional system to 10-30 seconds, making it suitable for efficient production in industrial production lines. Under this design condition, the acid anhydride component is utilized as a rigid skeleton segment inside the prepolymer and no longer participates in the final curing reaction.

[0009] Traditional amide-based curing networks are rigid and have limited chain segment movement, making efficient repair difficult even with the introduction of dynamic bonds. This invention directly embeds dynamic disulfide bonds into the resin backbone and combines them with flexible polyetheramine segments for molecular design. The flexible polyetheramine segments have good mobility at room temperature, which can effectively carry the disulfide bonds on the backbone to undergo rapid reversible exchange reactions, promoting the reorganization of the crosslinked network topology.

[0010] In this invention, low viscosity means viscosity < 100 mPa·s at 25°C.

[0011] The technical solution adopted by the present invention to solve the above-mentioned technical problems and achieve the above-mentioned technical effects is as follows: A method for preparing a self-healing UV-curable resin includes the following steps: The amino-terminated prepolymer is reacted with p-hydroxyanisole, glycidyl methacrylate and 4-dimethylaminopyridine, and then separated to obtain the product. The preparation method of the amino-terminated prepolymer includes the steps of adding an activator to the carboxyl-terminated prepolymer and reacting it, and adding a polyetheramine to react it. The method for preparing the carboxyl-terminated prepolymer includes the step of reacting a diol and an anhydride in a solvent.

[0012] Preferably, the self-healing UV-curable resin has the following structural formula (I): (I) Preferably, the structural formula (II) of the amino-terminated prepolymer includes:

[0013] (II) Preferably, the structural formula (Ⅲ) of the carboxyl-terminated prepolymer includes:

[0014] (III) Preferably, the mass amount of p-hydroxyanisole is 0.05-0.20% of the mass of glycidyl methacrylate.

[0015] Preferably, the molar ratio of the glycidyl methacrylate to the diol is 2:1.

[0016] Preferably, the mass amount of 4-dimethylaminopyridine is 0.08-0.12% of the mass of the amino-terminated prepolymer.

[0017] Preferably, the reaction temperature of the amino-terminated prepolymer with p-hydroxyanisole, glycidyl methacrylate, and 4-dimethylaminopyridine is 60 °C.

[0018] More preferably, the endpoint of the reaction between the amino-terminated prepolymer and p-hydroxyanisole, glycidyl methacrylate, and 4-dimethylaminopyridine is indicated by a Fourier transform infrared spectrum of the reactants at 910 cm⁻¹. -1 When the characteristic absorption peak disappears.

[0019] Preferably, the activator is one or more of N,N-dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, diisopropylcarbodiimide, 1-hydroxy-7-azabenzotriazole, 1-hydroxybenzotriazole, N-hydroxysuccinimide, and ethyl 2-cyano-2-(hydroxyimino)acetate.

[0020] More preferably, the activator is N,N-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole.

[0021] More preferably, the molar ratio of each compound in the activator to the carboxyl-terminated prepolymer is 1.0-1.5.

[0022] Preferably, the polyetheramine has a specification of D400.

[0023] More preferably, the molar ratio of the polyetheramine to the diol is 1.9-2.1:1.

[0024] Preferably, the reaction time for adding the activator is 1 hour.

[0025] Preferably, the reaction time for adding polyetheramine is 6 hours and the temperature is 25-40 °C.

[0026] More preferably, the endpoint of the reaction involving the addition of polyetheramine is less than 5 mgKOH / g, based on the acid value of the system.

[0027] Preferably, the diol has a disulfide bond.

[0028] Preferably, the molar ratio of the acid anhydride to the diol is 1.9-2.1:1.

[0029] Preferably, the solvent is selected from propylene carbonate.

[0030] Preferably, the method for preparing the carboxyl-terminated prepolymer further includes the step of purging nitrogen gas into the solvent to replace the air.

[0031] Preferably, the reaction of the diol and the anhydride in the solvent is carried out at a temperature of 50°C for 5 hours.

[0032] More preferably, the endpoint of the reaction between the diol and the anhydride in the solvent is that the acid value stabilizes.

[0033] Preferably, the diol is selected from 2-hydroxyethyl disulfide.

[0034] Preferably, the anhydride is selected from one or more of phthalic anhydride, maleic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, benzoic anhydride, and methylnadic anhydride.

[0035] More preferably, the anhydride is methylnadic anhydride.

[0036] The present invention also provides a self-healing UV-curable resin prepared by the above preparation method.

[0037] The present invention also provides a coating formed by curing the above-mentioned self-healing UV-curable resin, comprising the following raw materials in parts by weight: 40–80 parts of self-healing UV-curable resin; 5–30 parts of acrylate oligomer; 10–30 parts of reactive diluent; 1–5 parts of photoinitiator; 0.1–2 parts of adjuvant; The photoinitiator is an ultraviolet photoinitiator; The reactive diluent is a low-viscosity reactive monomer.

[0038] Preferably, the photoinitiator is selected from one or more of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0039] Preferably, the acrylate reactive diluent is selected from one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate.

[0040] More preferably, the acrylate reactive diluent is 1,6-hexanediol diacrylate.

[0041] As an example, the 1,6-hexanediol diacrylate was purchased from Chang Hsing Chemical Co., Ltd., Taiwan, China.

[0042] Preferably, the acrylate oligomer is selected from one or more of polyurethane acrylate oligomers, polyether acrylate oligomers, and epoxy acrylate oligomers.

[0043] Preferably, the additive is selected from one or more of leveling agents, defoamers, and adhesion promoters.

[0044] The present invention also provides the application of the above-mentioned self-healing UV-curable resin in the preparation of UV-curable coatings.

[0045] The present invention also provides the application of the above-mentioned self-healing UV-curable resin in the preparation of UV-curable adhesives.

[0046] This invention also provides the application of the above-mentioned self-healing UV-curable resin in the preparation of 3D printing consumables.

[0047] The present invention also provides the application of the above-mentioned self-healing UV-curable resin in the preparation of electronic device packaging materials.

[0048] The beneficial effects of this invention are as follows: This invention uses glycidyl methacrylate to precisely functionalize the amino-terminated prepolymer, converting the terminal amino group into a highly reactive acrylate double bond, thereby changing the crosslinking mechanism from slow thermal polymerization to rapid free radical polymerization initiated by ultraviolet light, and significantly shortening the curing time from hours in the traditional system to 10-30 seconds. This invention directly embeds dynamic disulfide bonds into the resin backbone and combines them with the flexible segments of polyetheramine for molecular design. Based on the good mobility of the flexible polyetheramine segments at room temperature, they can effectively carry the disulfide bonds on the backbone to undergo a rapid reversible exchange reaction, promoting the reorganization of the crosslinked network topology. This allows the coating to achieve complete scratch repair in a short time, while also giving the cured film a high elongation at break of 142%. This invention uses an anhydride-amide structure as the main chain backbone of the prepolymer, fully preserving the key properties imparted by amide bonds, such as excellent adhesion (up to grade 0 on various substrates) and good heat resistance (thermal decomposition temperature above 200℃). Compared with pure acrylate systems, the resin of this invention achieves functional upgrades in photocuring and self-healing without sacrificing the bulk mechanical and interfacial properties of the coating. This invention uses a medium-low temperature amidation reaction to construct the prepolymer, avoiding high-temperature side reactions and resulting in low energy consumption. The entire synthesis route does not use highly toxic isocyanates and uses propylene carbonate as an environmentally friendly solvent, thus solving the inherent defects of high toxicity and high pollution in the traditional polyurethane acrylate route. The endpoints of each reaction step in this invention are clearly defined (e.g., by monitoring acid value and characteristic infrared absorption peaks), the process has good repeatability, high batch stability, and is easy to scale up for industrial production. Attached Figure Description

[0049] Figure 1 The Fourier transform infrared spectrum of the 2-hydroxyethyl disulfide provided in Example 1 of this invention; Figure 2 The Fourier transform infrared spectrum of the self-healing UV-curable resin of Example 1 of this invention is shown below. Figure 3 This is a photograph of the coating formed by the self-healing UV-curable resin obtained in Example 2, under the initial state of scratches at 25 °C. Figure 4 The image shows the coating formed by the self-healing UV-curable resin obtained in Example 2 after scratch self-healing for 90 minutes at 25 °C. Figure 5 The image shows the coating formed by the self-healing UV-curable resin obtained in Example 2 after scratch self-healing for 180 minutes at 25 °C. Detailed Implementation

[0050] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0051] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0052] As an example, the leveling agent is an acrylate leveling agent, BYK Chemicals silicone surface additive, brand name BYK-333; The defoamer was purchased from BYK Chemicals' silicone defoamer, brand name BYK-066N; The adhesion promoter was purchased from Nippon Kayaku Adhesion Promoter, brand name PM-2; Polyether acrylate resin, purchased from BASF, Germany, polyether acrylate oligomer, grade PO 9034; Synthesis example 1 Preparation of carboxyl-terminated prepolymer: 0.1 mol 2-hydroxyethyl disulfide, 0.2 mol methylnadic anhydride, and 50 mL propylene carbonate were added to a three-necked flask, heated to 50 °C under nitrogen protection, and reacted for 5 h. The acid value stabilized at 45 mg KOH / g to obtain the carboxyl-terminated prepolymer.

[0053] Preparation of amino-terminated prepolymer: A carboxyl activator (0.22 mol of N,N-dicyclohexylcarbodiimide and 0.22 mol of 1-hydroxybenzotriazole) was added at room temperature for 1 h to activate the prepolymer. Then, 0.2 mol of polyetheramine D400 was added, and the mixture was heated to 40 °C and reacted for 6 h. After the reaction was complete, the reaction solution was cooled to room temperature, and the precipitated white solid N,N'-dicyclohexylurea (DCU) was removed by filtration. The filtrate was washed three times with saturated brine, dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the amino-terminated prepolymer.

[0054] Preparation of UV-curable resin: The temperature was lowered to 60 °C, and 0.05 g of p-hydroxyanisole, 0.2 mol of glycidyl methacrylate, and 0.8 g of 4-dimethylaminopyridine were added. The reaction was allowed to proceed for 4 h. Fourier transform infrared spectroscopy showed a value of 910 cm⁻¹. -1 The epoxy peak disappeared, and the solvent was removed by rotary evaporation to obtain a self-healing UV-curable resin.

[0055] In Synthesis Example 2, only the methyl nadic anhydride in Synthesis Example 1 was replaced with an equimolar amount of succinic anhydride; the other reaction processes were the same as in Synthesis Example 1.

[0056] In Synthesis Example 3, the only difference was that the polyetheramine D400 in Synthesis Example 1 was replaced with an equimolar amount of polypropylene glycol PPG400; the other reaction processes were the same as in Synthesis Example 1. Preparation of carboxyl-terminated prepolymer: 0.1 mol 2-hydroxyethyl disulfide, 0.2 mol methyl nadic anhydride, and 50 mL propylene carbonate were added to a three-necked flask, heated to 50 °C under nitrogen protection, and reacted for 5 h. The acid value stabilized at 45 mg KOH / g to obtain the carboxyl-terminated prepolymer.

[0057] Preparation of hydroxyl-terminated prepolymer: 2 mL of concentrated sulfuric acid was added as a catalyst, followed by 0.2 mol of polypropylene glycol (PPG400). The mixture was heated to 40 °C and reacted for 6 h. After the reaction was complete, the reaction solution was cooled to room temperature, and the precipitated white solid DCU was removed by filtration. The filtrate was washed three times with saturated brine, dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the hydroxyl-terminated prepolymer.

[0058] Preparation of UV-curable resin: The temperature was lowered to 60 °C, and 0.05 g of p-hydroxyanisole, 0.2 mol of glycidyl methacrylate, and 0.8 g of 4-dimethylaminopyridine were added. The reaction was allowed to proceed for 4 h. Fourier transform infrared spectroscopy showed a value of 910 cm⁻¹. -1 The epoxy peak disappeared, and the solvent was removed by rotary evaporation to obtain a self-healing UV-curable resin.

[0059] The synthesis of the self-healing UV-curable resin is specifically described in Synthesis Example 1.

[0060] Preparation of self-healing UV-curable resin compositions in Examples 1-4 and Comparative Examples 1-3 In this invention, the raw materials used in Examples 1-4 and Comparative Examples 1-3 are shown in the table below, where "-" indicates that no raw materials were added: Table 1. Raw materials and their quantities used in Examples 1-4 and Comparative Examples 1-3

[0061] According to the formulations in the table above, the preparation process of the UV-curable resin compositions containing self-healing resin or comparative resin in each example and comparative example is as follows: (1) Preparation of pre-dispersed slurry: The photoinitiator 1173, the reactive diluent 1,6-hexanediol diacrylate (HDDA), and the auxiliary agent PM-2 described in the formula were placed in a container and initially stirred at 1000 rpm for 10 min to obtain a premix. (2) Mixing and degassing: The self-healing UV resin and polyether acrylate resin PO 9034, the premix prepared in step (1), and the additives BYK-333 and BYK-066N in the amounts specified in Table 1 for each embodiment and comparative example were added to a mixing tank. Under light-protected conditions, the mixture was stirred at 1000 rpm for 15 min using a planetary gravity mixer. The vacuum degree was set to be controlled between -0.09 MPa and -0.1 MPa until all materials were mixed evenly to obtain a mixed slurry. Subsequently, the mixed slurry was filled and subjected to vacuum degassing and centrifugation. The degassing and centrifugation conditions were 2000 rpm for 10 min until there were no obvious bubbles in the slurry to obtain a degassed slurry.

[0062] Test case Preparation of self-healing UV-curable resin coating Coating and Curing: The degassed slurries obtained in each embodiment and comparative example were coated onto the surface of a glass substrate using a wire rod coater to form a wet film with a thickness of 40 μm. Subsequently, the substrate with the wet film was transferred to a curing device equipped with an ultraviolet light source (wavelength 365 nm) and cured at 500 mJ / cm². 2 The protective coating is formed by irradiating the material with ultraviolet light for 10 seconds.

[0063] Performance testing methods Curing time: The curing time was monitored using a UV curing energy meter, and the time corresponding to a double bond conversion rate of ≥95% was taken as the standard for complete curing; Mechanical properties: Tested according to GB / T 1040.3-2006, with a sample thickness of 100 μm and a tensile rate of 50 mm / min; Adhesion: Adhesion was determined using a cross-cut adhesion tester according to GB / T9286—1998 standard.

[0064] Pencil hardness: Tested using a pencil hardness tester according to GB / T 6739—1996 standard.

[0065] Self-healing performance: A scratch approximately 1 cm long and half the thickness of the film was made on the cured film using a brand new blade. After being left at room temperature (25℃) for a certain period of time, the scratch repair area was calculated by microscopic observation and the scratch repair effect was observed by taking pictures (scratch recovery area <10% is considered unrepairable, scratch recovery area >80% is considered basic repair, and scratch recovery area >90% is considered complete repair).

[0066] Table 2 Performance test data of Examples 1-4 and Comparative Examples 1-3

[0067] By comparing the above data, it can be seen that the resin system containing disulfide bonds has obvious self-healing ability and can basically achieve scratch repair.

[0068] Figure 1-5 The successful synthesis of the raw materials and target resin and the self-healing properties of the resin coating were verified. Figure 1 The Fourier transform infrared spectrum of the 2-hydroxyethyl disulfide in Example 1 can be used to verify the structural characteristics of the raw material and the effectiveness of the preparation. Figure 2 The infrared spectrum of the self-healing UV-curable resin prepared for Synthesis Example 1 can corroborate the successful synthesis of the target self-healing UV-curable resin.

[0069] Meanwhile, using the self-healing UV-curable resin coating prepared in Example 2 as the research object, self-healing performance tests were conducted at 25 ℃. Figure 3 , Figure 4 , Figure 5 The initial state of the coating scratch, the morphology after 90 minutes of self-healing, and the morphology after 180 minutes of self-healing are presented in sequence. This can intuitively and clearly reflect the healing process of the resin coating scratch as the repair time increases under normal temperature conditions, and provide intuitive morphological experimental evidence for the excellent room temperature self-healing performance of the UV-curable resin.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a self-healing UV-curable resin, characterized in that, Includes the following steps: The amino-terminated prepolymer is reacted with p-hydroxyanisole, glycidyl methacrylate and 4-dimethylaminopyridine, and then separated to obtain the product. The preparation method of the amino-terminated prepolymer includes the steps of adding an activator to the carboxyl-terminated prepolymer and reacting it, and adding a polyetheramine to react it. The method for preparing the carboxyl-terminated prepolymer includes the step of reacting a diol and an anhydride in a solvent.

2. The preparation method according to claim 1, characterized in that, The mass amount of p-hydroxyanisole is 0.05-0.20% of the mass of glycidyl methacrylate; The molar ratio of the glycidyl methacrylate to the diol is 2:1; The mass of 4-dimethylaminopyridine is 0.08-0.12% of the mass of the amino-terminated prepolymer.

3. The preparation method according to claim 1, characterized in that, The reaction temperature of the amino-terminated prepolymer with p-hydroxyanisole, glycidyl methacrylate and 4-dimethylaminopyridine is 60 °C. The endpoint of the reaction between the amino-terminated prepolymer and p-hydroxyanisole, glycidyl methacrylate, and 4-dimethylaminopyridine is indicated by a Fourier transform infrared spectrum of the reactants at 910 cm⁻¹. -1 When the characteristic absorption peak disappears.

4. The preparation method according to claim 1, characterized in that, The activator is one or more of N,N-dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, diisopropylcarbodiimide, 1-hydroxy-7-azabenzotriazole, 1-hydroxybenzotriazole, N-hydroxysuccinimide, and ethyl 2-cyano-2-(hydroxyimino)acetate.

5. The preparation method according to claim 1, characterized in that, The polyetheramine is specified as D400; The molar ratio of the polyetheramine to the diol is 1.9-2.1:

1.

6. The preparation method according to claim 1, characterized in that, The diol has disulfide bonds; The molar ratio of the acid anhydride to the diol is 1.9-2.1:

1.

7. The preparation method according to claim 1, characterized in that, The diol is selected from 2-hydroxyethyl disulfide; The anhydride is selected from one or more of phthalic anhydride, maleic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, benzoic anhydride, and methylnadic anhydride.

8. The self-healing UV-curable resin prepared by any one of the preparation methods according to claims 1-7.

9. A cured coating prepared using the self-healing UV-curable resin according to claim 8, characterized in that, Including the following parts by weight of raw materials: 40–80 parts of self-healing UV-curable resin; 5–30 parts of acrylate oligomer; 10–30 parts of reactive diluent; 1–5 parts of photoinitiator; 0.1–2 parts of adjuvant; The photoinitiator is an ultraviolet photoinitiator; The reactive diluent is a low-viscosity reactive monomer; The acrylate oligomer is selected from one or more of polyurethane acrylate oligomers, polyether acrylate oligomers, and epoxy acrylate oligomers; The additives are selected from one or more of leveling agents, defoamers, and adhesion promoters.

10. The application of the self-healing UV-curable resin of claim 8 in the preparation of UV-curable coatings, UV-curable adhesives, or 3D printing consumables.

Images