Preparation method of LED (light-emitting diode) ultraviolet curing resin and composite material thereof

Abstract

The invention provides a preparation method of LED (light-emitting diode) ultraviolet curing resin and a composite material thereof, according to the formula, epoxy resin E44 is used for modifying bisphenol A vinyl ester resin, triethylene glycol divinyl ether is used as an active diluent of a modification system, and 2, 4, 5-trimethyl-1, 3-pentanediol is used as a curing agent. The preparation method comprises the following steps: taking 2, 4, 6-trimethylbenzoyl phenyl ethyl phosphonate, triaryl hexafluoroantimonate sulfonium salt and diphenyl iodonium hexafluorophosphate as photoinitiators of a modification system, and taking dibenzoyl peroxide as a thermal initiator of the modification system; lED ultraviolet light is used for carrying out irradiation curing on the modified resin, and solid resin with excellent mechanical property and corrosion resistance is obtained. The resin prepared according to the formula provided by the invention can be used for repairing the inner wall of a pipeline and can also be combined with carbon fibers to prepare a composite material. LED ultraviolet light is used for curing, so that the efficiency is high, the energy consumption is low, the environment is protected, no pollution is caused, and the resin has good wettability on carbon fibers and high interfacial strength, can be laid on high-end equipment, and has important economic and social values.

Description

Technical Field

[0001] The present invention relates to the field of light-curing resins and composite materials thereof, and in particular to a method for preparing an LED ultraviolet light-curing resin and a composite material thereof. Background Art

[0002] Carbon fiber reinforced plastic (CFRP) is a high-performance material composed of carbon fibers as reinforcement and a resin matrix as a binder. It boasts high specific strength, high rigidity, fatigue resistance, and corrosion resistance, making it widely used in various industrial sectors. The performance advantages of this material stem from its multi-scale structural design: at the microscale, chemical bonding and mechanical interlocking form a stress transfer network at the fiber-matrix interface; at the mesoscale, ply design and fiber orientation control achieve anisotropic mechanical response; and at the macroscale, integral molding technology ensures structural integrity. Vinyl ester resin (Vinyl Ester Resin) offers excellent mechanical properties, chemical resistance, and fast curing speed, making it widely used in corrosion-resistant storage tanks, pipelines, exhaust gas desulfurization, land and sea transportation, and radiation curing. Its excellent interfacial bonding with the fiber reinforcement makes it an ideal matrix material for carbon fiber composites.

[0003] Ultraviolet (UV) curing technology is a process that uses ultraviolet radiation to trigger the rapid curing of photosensitive materials. It is widely used in coatings, inks, 3D printing and other fields. Compared with traditional thermal curing technology, UV curing has the characteristics of high curing efficiency, low energy loss, and environmental friendliness. The polymerization reaction of vinyl ester resin is a free radical polymerization, and photoinitiators can also be used to initiate polymerization by ultraviolet light. At present, there has been certain progress in the research on enhancing the wettability of vinyl ester resin on carbon fiber at home and abroad, and significant results have been achieved in the research and application of UV curing technology. However, the design modification to increase the photosensitivity of vinyl ester resin, the optimization of vinyl ester resin photocuring process, and the preparation and performance control of vinyl ester resin-based carbon fiber composites by ultraviolet light need further research.

[0004] Therefore, increasing the photocuring activity of vinyl ester resin (gel rate, hardness, etc.), exploring the photocuring process of vinyl ester resin under different application requirements (the mixing ratio of each component of the resin system, LED ultraviolet light irradiation conditions, etc.), and finding a method to improve the wettability of vinyl ester resin to carbon fiber while meeting the requirements of rapid and efficient preparation of UV-cured carbon fiber composites are of great significance for breaking through the energy consumption and efficiency limitations of traditional thermal curing processes of carbon fiber composites and promoting the upgrading of composite material manufacturing to green and intelligent. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for preparing an LED ultraviolet light-curing resin and a composite material thereof.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention is, on the one hand, to provide an LED UV-curable resin, comprising the following components in parts by weight: 60 parts of base resin, 15 parts of modifying resin, 25 parts of active diluent, 3 parts of photoinitiator, and 0-2 parts of thermal initiator.

[0007] Furthermore, the matrix resin is bisphenol A vinyl ester resin, and its ultraviolet light curing mechanism belongs to free radical light curing.

[0008] Furthermore, the modified resin is epoxy resin E44, and its UV curing mechanism belongs to cationic photocuring.

[0009] Furthermore, the active diluent is triethylene glycol divinyl ether (TGDE), which is a bifunctional monomer with dual polymerization activity. Under the action of a free radical initiator, it can participate in free radical polymerization; under the action of a sulfonium salt, it can participate in cationic polymerization; under the action of a mixed initiator, it can achieve free radical-cationic synergistic polymerization.

[0010] Furthermore, when the thermal initiator is 0 parts, the photoinitiator is 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L, free radical photoinitiator) and triaryl hexafluoroantimonate sulfonium salt (6976, cationic photoinitiator), and the weight ratio is 2:1; when the thermal initiator is not 0 parts, the photoinitiator is diphenyliodonium hexafluorophosphate (820), which can initiate both ring-opening polymerization of epoxy groups and cleavage polymerization of double bond functional groups, and is suitable for use in free radical-cationic hybrid photocuring systems.

[0011] Furthermore, the thermal initiator is dibenzoyl peroxide (BPO). When preparing UV-curable resin-based carbon fiber composite materials, the layers are laid in the order of fiber cloth-resin-fiber cloth-resin (a fixed process for hand lay-up molding, first lay a layer of carbon fiber cloth on the mold, then use a brush to evenly apply resin on the fiber cloth, then lay the next layer of fiber cloth, and use a roller to roll and apply pressure to ensure that the resin can fully impregnate each layer of fiber cloth. Repeat this operation until the predetermined number of layers are laid, and apply several layers of resin as many layers of fiber cloth as are laid, with the top layer being resin). After the modified resin in the top layer of the composite material is irradiated with ultraviolet light, it undergoes polymerization under the action of the photoinitiator, releasing heat. As the surface temperature of the material gradually rises to 70°C, the BPO in the interlayer is decomposed to generate benzoyloxy free radicals, which continue to initiate the polymerization of the epoxy resin-modified vinyl ester resin in the interlayer and induce the decomposition of the photoinitiator in the interlayer, so that the internal resin that cannot be irradiated by UV due to the shielding of the carbon fiber can be cured; at the same time, the top layer of resin continues to undergo polymerization under the action of BPO.

[0012] On the other hand, the technical solution of the present invention is to provide a method for preparing an LED ultraviolet curable resin, comprising the following steps:

[0013] (1) Weigh the base resin, modifying resin and active diluent according to weight and mix them evenly;

[0014] (2) Weighing a photoinitiator and a thermal initiator according to parts by weight, adding the photoinitiator and the thermal initiator to the mixture of step (1), and mixing uniformly;

[0015] (3) According to the use requirements, the mixture of step (2) is directly cured by LED ultraviolet light, or applied to other materials and then cured by LED ultraviolet light.

[0016] Furthermore, the method for uniform mixing in step (1) is: placing the mixture on a magnetic stirrer and stirring at 60° C. for 40 minutes.

[0017] On the other hand, the technical solution of the present invention is to provide a method for preparing an LED ultraviolet light-cured resin composite material, in which the curing resin is evenly applied on the fiber cloth in the order of fiber cloth-resin-fiber cloth-resin. After the next layer of fiber cloth is laid, a pressure roller is used to apply pressure to ensure that the resin can fully impregnate each layer of fiber cloth. This operation is repeated until the predetermined number of layers are laid, and then LED ultraviolet light is used for curing.

[0018] Furthermore, the wavelength of LED UV curing is 365nm, the light source intensity is 1kw, and the light efficiency is 1900~2100mW / cm 2 , the upper surface of the resin material is 100 mm away from the light source.

[0019] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0020] 1. The raw materials used in the present invention, such as bisphenol A vinyl ester resin and epoxy resin E44, are widely available, easy to obtain, inexpensive, widely used, and have high promotion value.

[0021] 2. The present invention uses a single wavelength of LED ultraviolet light to cure the resin, which is easy to operate, has low requirements on the site, simple reaction conditions, fast resin polymerization speed, low energy consumption, and is green, environmentally friendly and pollution-free.

[0022] 3. The present invention can be used for repairing the inner wall of a pipeline and for laying composite materials on the outer shell of a large device, without being restricted by the use environment and device size.

[0023] 4. The present invention constructs a free radical-cationic hybrid photocuring system, and the blending of two different system resins can form an IPN structure, thereby increasing the crosslinking degree of the polymer. The simultaneous use of a free radical photoinitiator (TPO-L) and a cationic photoinitiator (6976) (or a bifunctional initiator 820 having the above two mechanisms) can achieve the synergistic effect of the two reactions in a single system, combining the advantages of rapid curing, deep crosslinking, and complementary performance. When preparing composite materials, due to the "post-curing" effect of epoxy resin E44, new active centers are generated during chain termination. Even if the composite material is prepared and the UV light source is removed, the system can continue to undergo polymerization reactions in the absence of UV irradiation. This effect allows the hybrid photocuring system to be further crosslinked through a reasonable "post-curing" reaction after external curing under UV irradiation to compensate for the shortcomings of photocuring, and the interfacial strength between the resin and the fiber will also continue to increase over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 FTIR spectra of the modified resin system prepared in Example 1 before and after curing.

[0025] Figure 2 This is a cross-sectional SEM image of the E44 modified resin composite material using photoinitiator 820 prepared in Example 2.

[0026] Figure 3 This is a cross-sectional SEM image of the E44 modified resin composite material using dual photoinitiators prepared in Comparative Example 4. DETAILED DESCRIPTION

[0027] While the technical solutions in the embodiments of the present invention are clearly and completely described, it is clear that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Example 1: An LED UV-curable resin and its preparation method

[0029] An LED ultraviolet light-curing resin comprises the following components in parts by weight: 60 parts of bisphenol A vinyl ester resin, 15 parts of epoxy resin E44, 25 parts of triethylene glycol divinyl ether (TGDE), 2 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L, a free radical photoinitiator), and 1 part of triarylsulfonium hexafluoroantimonate (6976, a cationic photoinitiator).

[0030] A method for preparing an LED ultraviolet curing resin comprises the following steps:

[0031] (1) Weigh bisphenol A vinyl ester resin, epoxy resin E44, and TGDE according to weight, add all of them into a beaker and blend; because the viscosity of vinyl ester resin and epoxy resin E44 is relatively high, place the beaker on a magnetic stirrer during mixing, set the temperature to 60°C, and stir for 40 minutes;

[0032] (2) Weigh TPO-L and 6976 according to weight; after the resin in step (1) is evenly mixed and the viscosity drops to a level that no longer sticks to the glass rod, add TPO-L and 6976 to the evenly mixed resin, stir vigorously for 3 minutes, and then use an ultrasonic oscillator to shake for 15 minutes to thoroughly mix the two photoinitiators and disperse them in the resin;

[0033] (3) The resin obtained in step (2) was injected into a polytetrafluoroethylene mold (resin sample thickness 4 mm), placed in a UV curing box, and cured by LED UV light to obtain a resin casting; the wavelength of the LED UV curing was 365 nm, the light source intensity was 1 kW, and the light efficiency was 2000 mW / cm 2 The distance between the resin and the light source is 100 mm, and the irradiation time is 16 min.

[0034] Take part of the casting sample and use a ball mill to make it into powder. The powder is mixed with KBr at a mass ratio of 1:100. After grinding with an agate mortar, it is pressed into a tablet to make an infrared sample for testing. The liquid resin before curing (completed in step 2) is used as a comparison for infrared spectrum testing. The results are as follows Figure 1 As shown in the figure, it can be seen that before curing of the E44 modified system resin, the position of the epoxy group absorption peak shifted to the left. After curing, the C=C and epoxy group characteristic absorption peaks were significantly weakened or even disappeared, and the 1500cm -1 The absorption peak of -CH2 at 3475cm after curing is strengthened, indicating that the carbon-carbon double bond is broken, the epoxy group is ring-opened, and the polymerization reaction is complete. -1 The hydroxyl absorption peak becomes stronger, indicating that after the interpenetrating network polymer structure is formed, intermolecular hydrogen bonds are generated, the molecular chains are fully entangled, and the cross-linking network is complete.

[0035] According to GB / T2567-2021 "Test method for properties of resin castings", the resin castings were cut, and resin tensile and bending specimens were prepared for mechanical property testing; according to GB / T7193-2008 "Test method for unsaturated polyester resins", the gel fraction of the resin castings was tested; according to GB / T3854-2017 "Test method for Barcol hardness of reinforced plastics", the hardness of the resin castings was tested; at least 5 specimens were tested in parallel in the above experiments, and the experimental results are listed in Table 1.

[0036] Table 1. E44 modified resin performance test results

[0037] Serial number project Test results Test standards 1 tensile strength 68.7MPa GB / T2567-2021 2 Bending strength 119.4MPa GB / T2567-2021 3 Gel rate 97.4％ GB / T7193-2008 4 Barcol hardness 39HBa GB / T3854-2017

[0038] Example 2: An LED UV-curable resin composite material and its preparation method

[0039] An LED ultraviolet light-curing resin composite material comprises carbon fiber cloth and LED ultraviolet light-curing resin. The LED ultraviolet light-curing resin comprises the following components in parts by weight: 60 parts of bisphenol A vinyl ester resin, 15 parts of epoxy resin E44, 25 parts of triethylene glycol divinyl ether (TGDE), 3 parts of diphenyl iodonium hexafluorophosphate (820), and 2 parts of dibenzoyl peroxide (BPO).

[0040] A method for preparing an LED ultraviolet light-curing resin composite material comprises the following steps:

[0041] (1) Processing of carbon fiber cloth

[0042] ① Cut the carbon fiber cloth into a square cloth of 300×300mm. After wiping it with anhydrous ethanol to remove dust and other impurities on the surface, curl and fold the cloth and place it in a Soxhlet extractor. Insert the Soxhlet extractor into the flask, place it in a constant temperature oil bath, and secure it with an iron stand. Pour acetone into the flask through the Soxhlet extractor. Install a spherical condenser, set the temperature to 80℃, and heat to reflux for 24 hours.

[0043] ② Take the carbon fiber cloth out of the Soxhlet extractor, wash it with deionized water 4 to 5 times, then put it in an oven and dry it at 70°C for 12 hours. After taking it out, cool it to room temperature before use;

[0044] (2) Preparation of LED UV-curable resin

[0045] ① Weigh bisphenol A vinyl ester resin, epoxy resin E44, and TGDE according to parts by weight and add all of them into a beaker for blending. Due to the high viscosity of vinyl ester resin and epoxy resin E44, place the beaker on a magnetic stirrer at 60°C and stir for 40 minutes.

[0046] ② Weigh 820 and BPO according to weight; after the resin in step ① is evenly mixed and the viscosity drops to a level that no longer sticks to the glass rod, add 820 and BPO to the mixed resin, stir vigorously for 3 minutes, and then use an ultrasonic oscillator to shake for 15 minutes to thoroughly mix the photoinitiator and thermal initiator and disperse them in the resin;

[0047] (3) Preparation of composite materials

[0048] Take 5 sheets of processed 300×300mm carbon fiber cloth. In order to control the glue content of the composite material, weigh the resin prepared in step (2) according to the weight of the carbon fiber and lay it on a flat polytetrafluoroethylene plate. Use the hand-laying method to evenly apply the resin on the fiber cloth in the order of fiber cloth-resin-fiber cloth-resin. After laying the next layer of fiber cloth, use a roller to roll and apply pressure to ensure that the resin can fully impregnate each layer of fiber cloth. Repeat this operation until 5 layers of fiber cloth are laid and 5 layers of resin are applied. Place the laid composite material into a UV curing box (resin side facing LED UV light) and perform LED UV curing. The wavelength of LED UV curing is 365nm, the light source intensity is 1kW, and the light efficiency is 2000mW / cm 2 The distance between the resin and the light source was 100 mm, the irradiation time was 60 min, and the edges of the composite material were polished after irradiation.

[0049] According to GB / T1447-2005 "Test method for tensile properties of fiber reinforced plastics", GB / T3356-2014 "Test method for flexural properties of oriented fiber reinforced polymer matrix composites" and GB / T30969-2014 "Test method for short beam shear strength of polymer matrix composites", the specimens of composite tensile strength, composite flexural strength and composite interlaminar shear strength were carved respectively, and the three mechanical properties of the composite were tested using a universal mechanical testing machine; according to GB / T3854-2017 "Test method for Barcol hardness of reinforced plastics", the hardness of the composite was tested; the above experiments were conducted in parallel on at least 5 specimens, and the experimental results are listed in Table 2. In order to more intuitively characterize the impregnation of the modified resin on the carbon fiber, the fracture morphology of the composite was analyzed, and the cross-section SEM image of the E44 modified resin composite material with photoinitiator 820 is shown in the figure below. Figure 2 As shown, the resin has good wettability with the carbon fibers. The fracture surface is characterized by a large amount of resin matrix between the fibers, and the fracture is relatively smooth and neat, with no fiber pullout. Only a small amount of peeled flaky resin is present at the interface, indicating good interfacial bonding between the resin and the fibers. This allows for good stress transfer within the laminate, disperses the load on the resin, and enhances the composite's performance. Due to the post-curing effect of epoxy resin E44, the strength of the resin-fiber interface will increase over time.

[0050] Table 2. Performance test results of E44 modified resin composite materials

[0051] Serial number project Test results Test standards 1 tensile strength 424.4MPa GB / T1447-2005 2 Bending strength 355.5MPa GB / T3356-2014 3 Interlaminar shear strength 45MPa GB / T30969-2014 4 Barcol hardness 45HBa GB / T3854-2017

[0052] To illustrate the effects of the present invention, comparative examples 1 (unmodified bisphenol A vinyl ester resin), 2 (modified bisphenol A vinyl ester resin using epoxy resin TDE85), 3 (modified bisphenol A vinyl ester resin using E44 with 651 and 6976 as photoinitiators), and 4 (modified bisphenol A vinyl ester resin composite material using TPO-L and 6976 as photoinitiators) were selected for performance comparison. The specific comparative examples and results are as follows:

[0053] Comparative Example 1:

[0054] In order to prove that the mechanical properties of bisphenol A vinyl ester resin modified with E44 are superior, this comparative example differs from Example 1 in that no epoxy resin E44 is added, and the unmodified bisphenol A vinyl ester resin is directly cured. The raw materials of this comparative example are (by weight): 75 parts of bisphenol A vinyl ester resin, 25 parts of reactive diluent TGDE, and 3 parts of photoinitiator TPO-L. The preparation method is similar to Example 1. The resin casting is obtained by irradiation curing, and samples are cut according to the corresponding national standards. The mechanical properties, gel fraction, hardness, etc. of the unmodified resin are tested. The tests show that the cured resin prepared in this comparative example has a gel fraction of 91.2%, a tensile strength and a flexural strength of 58.2 MPa and 100.5 MPa, respectively, and a Barcol hardness of 36 HBa.

[0055] By comparing Example 1 and Comparative Example 1, it can be seen that compared with the unmodified bisphenol A vinyl ester resin, the mechanical properties of the modified resin are significantly improved after adding epoxy resin E44, and the gel rate is increased. After modification, the molecular chains of the two resins interpenetrate with each other, forming an IPN structure, which improves the strength and toughness of the resin system. Furthermore, the formation of the free radical-cationic hybrid photocuring system, due to the synergistic effect of the initiator, the volume complementary effect and the performance complementary effect, the acid active center catalyzes the ring-opening polymerization of the epoxy resin or vinyl ether, provides deep curing, and improves the polymerization efficiency of the resin. The ring opening of the epoxy group reduces the volume shrinkage of the resin. Free radical and cationic polymerization occur in the same system, reducing the oxygen inhibition and water inhibition effects. The "post-curing" reaction of epoxy resin E44 further cross-links the system, compensating for the shortcomings of photocuring and improving the gel rate. Therefore, the performance of the modified resin in Example 1 is even better.

[0056] Comparative Example 2:

[0057] To demonstrate the superior mechanical properties of bisphenol A vinyl ester resin modified with E44, this comparative example differs from Example 1 in that the epoxy resin E44 was replaced with epoxy resin TDE85 for modification and curing, following the same preparation method as in Example 1. The resulting resin castings were irradiated and cured, and specimens were cut according to the corresponding national standards for testing the mechanical properties, gel fraction, and hardness of the TDE85-modified resin. The cured resin prepared in this comparative example exhibited a gel fraction of 82.2%, a tensile strength of 50.4 MPa and a flexural strength of 85.8 MPa, respectively, and a Barcol hardness of 31 HBa.

[0058] Comparison of Example 1 and Comparative Example 2 shows that, compared to modification with epoxy resin E44, the hybrid photocuring system modified with TDE85 exhibits significantly lower mechanical strength, reduced hardness, and decreased gel fraction, resulting in poor modification results. Two main hypotheses suggest this may be due to the following: First, the poor crosslinking between epoxy resin TDE85 and the reactive diluent results in a low gel fraction, leading to phase separation with bisphenol A vinyl ester resin during blending, impacting mechanical properties; second, epoxy resin TDE85 exhibits a severe light-shielding effect and poor photosensitivity, making it unsuitable for use in free radical-cationic hybrid photocuring systems and unable to modify bisphenol A vinyl ester resin under UV curing conditions.

[0059] Comparative Example 3:

[0060] In order to prove that the curing effect of the E44 modified bisphenol A vinyl ester resin using the combination of photoinitiator TPO-L + 6976 is better, the difference between this comparative example and Example 1 is that the photoinitiator benzoin dimethyl ether (651) is used instead of TPO-L in combination with 6976, and the number of added parts remains unchanged. The preparation method is based on Example 1. The resin casting is obtained by irradiation curing, and the samples are cut according to the corresponding national standards to test the mechanical properties, gel rate, hardness, etc. of the E44 modified resin. The test results show that the cured resin prepared in this comparative example has a gel rate of 87.6%, a tensile strength and a flexural strength of 54.1 MPa and 95.2 MPa respectively, and a Barcol hardness of 34 HBa.

[0061] Comparison of Example 1 and Comparative Example 3 reveals that the mechanical strength and gel fraction of the E44-modified resin cross-linked and cured using photoinitiators 651 and 6976 are significantly lower than those using photoinitiators TPO-L and 6976. This decline in performance may be due to overcuring of the surface layer due to the short-wavelength absorption properties of photoinitiator 651, which leads to attenuation of photon flux in deeper layers, resulting in reduced cured thickness and gel fraction for the same UV irradiation time. Furthermore, 651 decomposes rapidly, generating a large number of benzoyl radicals in a short period of time, which can easily trigger oxygen inhibition. This generates bubbles during the curing reaction, causing wrinkles and defects on the sample surface, and reducing the mechanical strength of the resin.

[0062] Comparative Example 4:

[0063] In order to prove that the interface strength between E44 modified resin and fiber is higher after using photoinitiator 820, the difference between this comparative example and Example 2 is that a mixture of photoinitiator TPO-L and photoinitiator 6976 with a weight ratio of 2:1 is used instead of photoinitiator 820 to participate in the preparation of E44 modified resin composite materials. The specific method is shown in Example 2. The samples are cut according to the corresponding national standards, the mechanical properties of the composite materials are tested, and then the cross-section of the composite materials is scanned and analyzed. It can be seen from the test that the E44 modified resin composite material prepared in this comparative example has a bending strength, tensile strength and interlaminar shear strength of 312.1MPa, 91.9MPa and 13.1MPa respectively, and a Barcol hardness of 40HBa. The cross-sectional SEM image is as shown below. Figure 3 shown.

[0064] By comparing Example 2 and Comparative Example 4, Figure 3 Composites prepared with E44-modified resin and carbon fibers using photoinitiators TPO-L and 6976 exhibit poor mechanical properties and low interfacial bonding strength. The resin's ability to wet the carbon fibers is poor, and the degree of resin cure within the composite is also low. The fracture surfaces of E44-modified laminates exhibit numerous voids between the carbon fibers, resulting in uneven fractures, significant carbon fiber pullout, and severe resin debonding. The resin is virtually no longer adherent to the carbon fiber surfaces. A comprehensive analysis of mechanical properties and micromorphology reveals that the resin within the laminates does not fully participate in the cure reaction, resulting in low adhesive content, insufficient fiber adhesion, numerous internal voids, and a lack of resin bonding between carbon fiber layers, leading to poor overall performance. The uncured component is primarily the epoxy resin E44. This is presumably because the decomposition of the thermal initiator BPO is unable to induce the decomposition of 6976, or the decomposition rate is slow. In the hybrid photothermal curing system, BPO only plays a supporting role in the curing of E44. The absence of 6976 contributes to the low degree of E44 cure, compromising the overall composite performance.

[0065] Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto but is only constrained by the appended claims and can be readily modified and varied by one of ordinary skill in the art without departing from the spirit and scope of the present invention.

Claims

1. An LED UV-curable resin, characterized in that: The invention comprises the following components in parts by weight: 60 parts of base resin, 15 parts of modifying resin, 25 parts of active diluent, 3 parts of photoinitiator and 0-2 parts of thermal initiator.

2. The LED UV-curable resin according to claim 1, characterized in that: The base resin is bisphenol A vinyl ester resin.

3. The LED UV-curable resin according to claim 1, characterized in that: The modified resin is epoxy resin E44.

4. The LED UV-curable resin according to claim 1, characterized in that: The active diluent is triethylene glycol divinyl ether.

5. The LED UV-curable resin according to claim 1, characterized in that: When the thermal initiator is 0 parts, the photoinitiator is 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester and triaryl hexafluoroantimonate sulfonium salt, with a weight ratio of 2:1; when the thermal initiator is not 0 parts, the photoinitiator is diphenyliodonium hexafluorophosphate.

6. The LED UV-curable resin according to claim 1, characterized in that: The thermal initiator is dibenzoyl peroxide.

7. A method for preparing the LED UV-curable resin according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Weigh the base resin, modifying resin and active diluent according to parts by weight and mix them evenly; (2) Weighing a photoinitiator and a thermal initiator according to parts by weight, adding the photoinitiator and the thermal initiator to the mixture of step (1), and mixing uniformly; (3) According to the use requirements, the mixture of step (2) is directly cured by LED ultraviolet light, or applied to other materials and then cured by LED ultraviolet light.

8. The preparation method according to claim 7, characterized in that The method for uniform mixing in step (1) is: placing the mixture on a magnetic stirrer and stirring at 60° C. for 40 minutes.

9. A method for preparing an LED ultraviolet light-cured resin composite material, characterized in that: The curable resin according to any one of claims 1 to 6 is evenly applied on the fiber cloth in the order of fiber cloth-resin-fiber cloth-resin. After laying the next layer of fiber cloth, a pressure roller is used to apply pressure to ensure that the resin can fully impregnate each layer of fiber cloth. This operation is repeated until the predetermined number of layers are laid, and then the resin is cured by LED ultraviolet light irradiation.

10. The preparation method according to claim 7 or the preparation method according to claim 9, characterized in that: The wavelength of LED UV curing is 365nm, the light source intensity is 1kw, and the light efficiency is 1900~2100mW / cm 2 , the upper surface of the resin material is 100 mm away from the light source.

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