Outdoor weather-resistant composite photoinitiator and preparation method thereof

Abstract

The invention provides an outdoor weather-resistant composite photoinitiator and a preparation method thereof. The photoinitiator has the characteristics of high photo-initiation efficiency, excellent ultraviolet stability, strong antioxidant inhibition capability, good humidity and heat resistance, good compatibility with resin, long-term storage stability and the like. By introducing a main initiator component modified by a specific structure, the spectral response is widened, and the intrinsic stability is improved; by constructing a composite stable protection system taking a nano material as a carrier, the synergism of multiple stable mechanisms such as ultraviolet absorption, free radical capture, peroxide decomposition and the like is realized, and the competitive light absorption contradiction between a stabilizer and an initiator is avoided; by introducing the light-triggered oxygen release microcapsules and the electron transfer accelerator, oxygen is effectively quenched at the initial stage of curing, the initiation efficiency is improved, and the surface drying performance under the outdoor condition is remarkably improved; the finally prepared granular product is convenient to use and good in dispersity, and is especially suitable for outdoor photocureable coatings, printing ink and other systems with strict requirements on weather resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoinitiators, in particular to an outdoor weather-resistant composite photoinitiator and a preparation method thereof. BACKGROUND

[0002] Radiation curing technology, especially ultraviolet (UV) curing technology, has been widely used in the fields of coatings, inks, adhesives, etc. due to its high efficiency, energy saving, environmental protection and other advantages. With the continuous expansion of application scenarios, the requirements for the performance of UV curing materials are also increasing, especially in long-term outdoor use scenarios such as outdoor architectural coatings, automotive finishing varnish, outdoor signs and packaging, etc. The outdoor environment is complex and harsh, and materials are exposed to sunlight, ultraviolet radiation, oxygen, moisture, temperature changes and other factors for a long time, which is prone to photo-oxidative aging, resulting in problems such as yellowing, powdering, cracking, loss of gloss, and decreased adhesion of the coating.

[0003] As the core component of the UV curing system, the performance of photoinitiators directly determines the curing efficiency and final performance of the material. However, traditional photoinitiators (such as α-hydroxy ketones, acyl phosphine oxides, etc.) face significant challenges in outdoor applications: first, their own or photolysis products are chemically unstable under long-term ultraviolet irradiation, prone to decomposition or side reactions, resulting in a decrease in initiation efficiency and the generation of chromophores that cause yellowing of the coating; second, during outdoor curing, the atmospheric oxygen has a more obvious inhibition effect on free radical polymerization (oxygen inhibition), which seriously affects the surface curing effect and leads to tackiness and insufficient hardness of the coating; third, moisture can interfere with the curing process and accelerate the hydrolysis of some photoinitiators (such as acyl phosphine oxides); fourth, there is a lack of effective protection against deep ultraviolet light (especially UV-A and UV-B bands), which cannot protect the resin matrix from photoaging.

[0004] In order to improve the outdoor durability of the photoinitiating system, the prior art usually adopts a simple compounding method, for example, adding a small amount of ultraviolet absorber (UVA) or hindered amine light stabilizer (HALS) to the photoinitiator. For example, some patents disclose the co-use of benzophenone or thioxanthone photoinitiators with triazine ultraviolet absorbers. However, this simple physical mixing has obvious disadvantages: first, the compatibility between the added UVA / HALS and the photoinitiator, the resin matrix may be poor, and migration or precipitation may occur; second, while the UVA shields the harmful ultraviolet light to protect the matrix, it also competes for the ultraviolet light required for curing, which may result in incomplete curing, requiring a substantial increase in the amount of photoinitiator or light energy, increasing the cost and energy consumption; third, conventional HALS mainly act on the free radicals generated during the aging of the polymer matrix, and have limited effect on the light stability of the photoinitiator itself. In addition, to address the oxygen inhibition problem for outdoor applications, methods such as adding a large amount of active amine co-initiator or increasing the light intensity are usually used, but this may cause problems such as odor, accelerated yellowing, or increased energy consumption. Therefore, the prior art solutions often have to make compromises and it is difficult to achieve a good balance between efficient initiation, deep curing, excellent surface drying and long-term outdoor weather resistance.

[0005] In summary, the development of a photoinitiator that can inherently balance high efficient photoinitiating activity and excellent outdoor environmental resistance, especially one that can synergistically solve the problems of ultraviolet stability, oxygen inhibition resistance and hydrolysis resistance, is a key technical problem that needs to be solved in the process of expanding the outdoor high-end applications of UV curing technology in the field. SUMMARY

[0006] The present application provides a weather-resistant composite photoinitiator for outdoor use and a preparation method thereof, which addresses the problems of poor weather resistance, susceptibility to oxygen inhibition and moisture, and compatibility and efficiency conflicts with simple compounding of stabilizers in conventional photoinitiators in the prior art. The composite photoinitiator of the present application realizes the organic combination and synergistic effect of each functional unit at the molecular level and microstructure through the multi-component compounding and structural modification of the carefully designed main initiation system, stabilizing and protecting system and synergistic system.

[0007] To achieve the above-mentioned object, the present application provides the following solutions: The present application provides a weather-resistant composite photoinitiator for outdoor use, which comprises the following components by weight percentage: The main photoinitiator system 40%-60% comprises: modified alpha-hydroxy ketone derivative 20%-30%; acyl phosphine oxide derivative 10%-15%; thioxanthone-carbazole complex 8%-12%; The stable protection system comprises 25%-35%, including: 10%-15% hindered amine light stabilizer modifier; 8%-12% composite ultraviolet absorber, wherein the composite ultraviolet absorber is composed of benzotriazole and triazine ultraviolet absorbers in a 1:1 weight ratio; 4%-6% metal chelate stabilizer; and 3%-5% hydrophobically modified nano-silica, wherein the hydrophobically modified nano-silica has a particle size of 20-50 nm and is grafted with octadecyl chains on its surface. The synergistic system comprises 15%-25% of the following components: 6%-10% of an electron donor-acceptor complex, wherein the electron donor-acceptor complex is a complex of N-phenylglycine derivative and anthraquinone; 5%-8% of oxygen scavenging microcapsules, wherein the core of the oxygen scavenging microcapsules is ascorbate palmitate and the capsule wall is polyurethane; and 4%-7% of a leveling-wetting modifier, wherein the leveling-wetting modifier is polyether-modified polysiloxane and its end group is photocurable acrylate group.

[0008] Preferably, the modified α-hydroxy ketone derivative is an α-hydroxy isobutyrylbenzene derivative with a tert-butylbenzoate structure introduced into the side chain; the acylphosphine oxide derivative is an acylphosphine oxide with an resistant hydrolytic siloxane segment introduced into the side chain; and the thioxanthone-carbazole complex is a molecular complex of thioxanthone and carbazole with dual-band absorption at 300-380 nm and 420-480 nm.

[0009] Preferably, the metal chelate stabilizer is a copper-zinc bimetallic organic complex; the oxygen scavenging microcapsules have a particle size of 2-5 μm and a wall thickness of 0.5-1 μm.

[0010] This invention also provides a method for preparing an outdoor weather-resistant composite photoinitiator, comprising the following steps: S1. Preparation of the main photoinitiator: Under inert gas protection, α-hydroxyisobutyrylbenzene and tert-butylbenzoyl chloride are subjected to an acylation reaction in an organic solvent at 80-120℃. Subsequently, an ester exchange catalyst is added, and the ester exchange reaction is carried out at 120-140℃ under reduced pressure. After the reaction is completed, the mixture is cooled to crystallize, filtered, washed, and dried to obtain the modified α-hydroxy ketone derivative. S2. Preparation of stable protective pre-dispersion: Disperse hydrophobically modified nano-silica in an alcohol solvent, sonicate, add a composite ultraviolet absorber and continue sonication, then transfer to a high-pressure homogenizer for homogenization, then add a hindered amine light stabilizer modifier and a metal chelate stabilizer, stir and compound at 50-60℃ to obtain a stable protective pre-dispersion. S3. Preparation of oxygen scavenging microcapsules: Ascorbate palmitate core material is melted and emulsified in an aqueous phase containing an emulsifier to form an oil-in-water emulsion; an organic solution of isocyanate and an aqueous solution of polyamine are added dropwise to the emulsion, and an interfacial polymerization reaction is carried out at 40-50℃ and pH 8-9. After the reaction is completed, the microcapsules are collected by centrifugation, washed, and dried to obtain the oxygen scavenging microcapsules. S4. Composite Blending: Weigh the main photoinitiator, stabilizing and protective pre-dispersion, electron donor-acceptor complex, oxygen scavenging microcapsules, and leveling-wetting modifier according to the specified ratio, add organic solvent under inert gas protection and stir to dissolve to obtain a mixed slurry; S5. Fine dispersion and post-processing: The mixed slurry obtained in step S4 is ground and sand-milled in sequence until the fineness is ≤5μm. Then, the solvent is removed under vacuum conditions at 60-70℃. The resulting molten material is extruded through a twin-screw extruder, granulated underwater, and dried to obtain granular outdoor weather-resistant composite photoinitiator.

[0011] Preferably, in step S1, the transesterification catalyst is tetraisopropyl titanate, and the vacuum degree of the reduced pressure condition is not lower than -0.095 MPa; in step S2, the pressure of the high-pressure homogenizer is 70-80 MPa, and the number of homogenization times is 3-5; in step S3, the isocyanate is isophorone diisocyanate, and the polyamine is ethylenediamine.

[0012] The present invention also provides a photocurable composition comprising a photocurable resin, an active diluent, and an outdoor weather-resistant composite photoinitiator.

[0013] Preferably, the content of the outdoor weather-resistant composite photoinitiator is 1%-10% based on the total weight of the photocurable composition.

[0014] The present invention also provides an outdoor coating made of a light-curing composition.

[0015] The present invention also provides an outdoor ink made of a photocurable composition.

[0016] This invention also provides the application of an outdoor weather-resistant composite photoinitiator in the preparation of outdoor weather-resistant photocurable materials.

[0017] The present invention achieves the following beneficial technical effects compared to the prior art: This invention provides an outdoor weather-resistant composite photoinitiator and its preparation method. The photoinitiator features high photoinitiation efficiency, excellent UV stability, strong antioxidant capacity, good resistance to damp heat, good compatibility with resins, and long-term storage stability. By introducing a main initiator component with specific structural modifications, the spectral response is broadened and intrinsic stability is improved. By constructing a composite stabilizing and protective system with nanomaterials as carriers, multiple stabilization mechanisms such as UV absorption, free radical capture, and peroxide decomposition are synergistically achieved, while avoiding the competitive light absorption conflict between the stabilizer and the initiator. By introducing photo-triggered oxygen release microcapsules and electron transfer promoters, oxygen is effectively quenched in the early stage of curing, improving initiation efficiency and significantly improving surface drying performance under outdoor conditions. The final granular product is easy to use and has good dispersibility, making it particularly suitable for outdoor UV-curable coatings, inks, and other systems with stringent weather resistance requirements. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating the preparation method of the outdoor weather-resistant composite photoinitiator provided by this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide an outdoor weather-resistant composite photoinitiator and its preparation method, so as to solve the problems existing in the prior art.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1: This embodiment provides a method for preparing an outdoor weather-resistant composite photoinitiator, such as... Figure 1 As shown, it includes the following steps: S1-1. Preparation of modified α-hydroxyketone derivatives: Under nitrogen protection, 50.0 g of α-hydroxyisobutyrylbenzene and 150 mL of xylene were added to a 500 mL three-necked flask equipped with a stirrer, thermometer, and dropping funnel, and the temperature was raised to 80 °C. 45.6 g of tert-butylbenzoyl chloride was slowly added dropwise, ensuring the addition was completed within 1 hour. The temperature was raised to 120 °C and the reaction was carried out for 4 hours, with the reaction endpoint monitored by TLC. The temperature was lowered to 60 °C, and 0.5 g of tetraisopropyl titanate catalyst was added. The reaction was carried out at -0.095 MPa and 140 °C for 3 hours, followed by transesterification and distillation to remove byproducts. The reaction solution was cooled to room temperature, poured into 200 mL of methanol to crystallize, filtered, washed three times with cold methanol, and dried at 50 °C and 100 Pa for 12 hours to obtain a white crystalline product with a yield of approximately 85%.

[0024] S1-2. Preparation of a stable protective predispersant: Weigh 5.0 g of nano-silica with surface-grafted octadecyl chains (particle size approximately 30 nm), disperse it in 50 mL of isopropanol, and sonicate at 500 W and 40 kHz for 30 min. Add 4.0 g of benzotriazole UVA (Tinuvin 384) and 4.0 g of triazine UVA (Tinuvin 400), and continue sonication for 15 min. Transfer the dispersion to a high-pressure homogenizer and homogenize it 5 times at 80 MPa. Transfer the homogenized slurry to a reactor, add 12.0 g of HALS-modified material (self-synthesized) with both tetramethylpiperidinyl and benzotriazole structures and 5.0 g of copper / zinc bimetallic chelate stabilizer, and stir at 60 °C for 2 h to obtain a uniform stable protective predispersant.

[0025] S1-3. Preparation of Oxygen-Scavenging Microcapsules: 15g of ascorbate palmitate and 5g of liquid paraffin were mixed and heated to 70℃ to melt. The melt was added to 100g of deionized water containing 2g of Span-80 under high-speed stirring (10000rpm), and emulsified for 10min to form an oil-in-water emulsion. 8g of isophorone diisocyanate was dissolved in 20mL of toluene. Under conditions of 45℃ and pH=8.5 (adjusted with triethylamine), the isocyanate solution and 20mL of aqueous solution containing 2.4g of ethylenediamine were slowly added dropwise to the emulsion simultaneously, controlling the addition time to about 2h. After the addition was complete, the reaction was continued for 4h. After the reaction was completed, the microcapsules were separated by centrifugation, washed three times successively with deionized water and ethanol, dried under vacuum at 40℃, and passed through a 200-mesh sieve to obtain white powdery microcapsules with an encapsulation efficiency of about 87%.

[0026] S1-4. Composite Blending: Weigh the following components according to the following weight ratios: 25g of the component obtained in step S1-1, 12g of commercially available acylphosphine oxide derivative (containing siloxane segments, Speedcure TPO-L), 10g of the thioxanthone-carbazole complex (self-synthesized), approximately 28g of the stable protective pre-dispersion obtained in step S1-2 (dry weight), 8g of the N-phenylglycine derivative and anthraquinone complex (self-synthesized), 7g of the oxygen scavenging microcapsules obtained in step S1-3, and 10g of polyether-modified acrylate-terminated polysiloxane (BYK-371). Add the above solid components to 30% of the total weight of ethyl acetate and stir under nitrogen protection in a 50°C water bath until completely dissolved or dispersed.

[0027] S1-5, Fine Dispersion and Post-treatment: The mixed slurry obtained in S1-4 is ground three times using a three-roll mill (roller spacing of 50μm, 30μm, and 15μm respectively), and then transferred to a basket mill and ground with 0.3mm zirconia beads for 2 hours. The fineness is sampled and tested to be ≤5μm. The slurry is transferred to a thin-film evaporator and the solvent is removed at 65℃ and -0.098MPa until the residual solvent content is ≤0.1%. The resulting viscous molten material is extruded through a twin-screw extruder (screw temperature: first stage 80℃, second stage 100℃, third stage 90℃), and underwater pelletized to obtain light yellow granules with a particle size of 2-3mm, which is the outdoor weather-resistant composite photoinitiator.

[0028] Example 2: The preparation steps are basically the same as in Example 1, except that the weight ratios of each component in steps S1-4 are adjusted as follows: 22g of modified α-hydroxy ketone derivative, 15g of acylphosphine oxide derivative, 8g of thioxanthone-carbazole complex, 30g of stabilizing and protective pre-dispersion (dry weight), 9g of electron donor-acceptor complex, 6g of oxygen scavenging microcapsules, and 10g of leveling-wetting modifier. The final product is an outdoor weather-resistant composite photoinitiator.

[0029] Comparative Example 1: Weigh 2-isopropylthioxanthone (ITX), methyl benzoylformate (MBF), and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) in a weight ratio of 1:1:2, pulverize and mix the solid components to obtain a physically mixed photoinitiator.

[0030] Comparative Example 2: The preparation steps are the same as in Example 1, but the stable protective pre-dispersion prepared in step S1-2 is completely omitted in the S1-4 ratio. Its weight proportion is made up by equal amounts of main initiator and electron donor-acceptor complex in the original ratio, while other components and amounts remain unchanged, thus obtaining the composite photoinitiator.

[0031] Comparative Example 3: The preparation steps are the same as in Example 1, but the oxygen scavenging microcapsules are omitted in the S1-4 ratio, and their weight proportion is made up by an equal amount of leveling-wetting modifier to obtain the composite photoinitiator.

[0032] Performance testing The photoinitiator prepared above was applied to the following basic UV-curable coating formulations for performance evaluation: Epoxy acrylate (EM-265): 35 wt% Tripropylene glycol diacrylate (TPGDA): 25 wt% Trimethylolpropane triacrylate (TMPTA): 30 wt% Photoinitiator sample: 5 wt% Leveling agent (BYK-333): 0.5 wt% Defoamer (TEGO Foamex 810): 0.5 wt% The components were mixed thoroughly, and the coating was applied to clean glass and tinplate plates using a wire bar coater, with a film thickness of approximately 50 μm. An irradiation device equipped with 385nm LED beads was used (irradiance 100 mW / cm²). 2 The material was cured under conditions with an exposure time of 5 seconds. The test results are shown in the table below:

[0033]

[0034] The activity retention rate is calculated by comparing the change in the minimum curing energy (measured by Photo-DSC) required to induce curing of the same formulation before and after storage.

[0035] Results Analysis The test results in the table above show that: Compared with Comparative Example 1, the composite photoinitiators prepared in Examples 1 and 2 of this invention, while having comparable or even better curing efficiency (surface drying, hardness), exhibit significantly improved weather resistance (gloss retention, color difference, chalking after QUV aging) and hygrothermal stability, as well as better storage stability. This indicates that this invention achieves comprehensive performance optimization through component design and process integration, rather than a simple addition.

[0036] Comparative Example 2 lacked a stable protective system, resulting in a significant decrease in its QUV aging performance, an increase in color difference, and noticeable color changes during storage. This indicates that the system is crucial for long-term outdoor weather resistance and the product's own storage stability.

[0037] Comparative Example 3, lacking oxygen-scavenging microcapsules, exhibited significantly poorer surface drying properties and lower hardness, demonstrating that these microcapsules play a crucial role in improving surface curing performance under outdoor curing conditions (especially in oxygen-rich environments).

[0038] The performance of Example 1 and Example 2 is similar, indicating that excellent overall performance can be obtained by adjusting the ratio within the content range provided by the present invention.

[0039] In summary, the outdoor weather-resistant composite photoinitiator and its preparation method provided by this invention effectively solve the key technical bottlenecks of traditional photoinitiators in outdoor applications, exhibiting excellent comprehensive performance and possessing high practical value and market prospects.

[0040] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] It should be noted that the components mentioned in the above embodiments are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0042] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. An outdoor weather-resistant composite photoinitiator, characterized by, By weight percentage, comprising the following components: Main photoinitiator system 40%-60%, comprising: modified alpha-hydroxy ketone derivative 20%-30%; acyl phosphine oxide derivative 10%-15%; thioxanthone-carbazole complex 8%-12%; Stable protection system 25%-35%, comprising: hindered amine light stabilizer modifier 10%-15%; composite ultraviolet absorber 8%-12%, the composite ultraviolet absorber is compounded by benzotriazole and triazine ultraviolet absorber in a weight ratio of 1:1; metal chelate stabilizer 4%-6%; hydrophobic modified nano-silica 3%-5%, the particle size of the hydrophobic modified nano-silica is 20-50nm, and the surface is grafted with octadecyl chain; Synergistic system 15%-25%, comprising: electron donor-acceptor complex 6%-10%, the electron donor-acceptor complex is a complex of N-phenyl glycine derivative and anthraquinone; oxygen scavenging microcapsule 5%-8%, the core of the oxygen scavenging microcapsule is ascorbyl palmitate, and the wall is polyurethane; leveling-wetting modifier 4%-7%, the leveling-wetting modifier is polyether modified polysiloxane, and the end group is photocurable acrylate group.

2. The weather-resistant composite photoinitiator for outdoor use according to claim 1, characterized by, The modified alpha-hydroxy ketone derivative is alpha-hydroxy isobutyryl benzene derivative with side chain introducing t-butyl benzoate structure; the acyl phosphine oxide derivative is acyl phosphine oxide introducing anti-hydrolysis siloxane segment; the thioxanthone-carbazole complex is molecular complex of thioxanthone and carbazole with double-band absorption at 300-380nm and 420-480nm.

3. The weather-resistant composite photoinitiator for outdoor use according to claim 1, characterized by, The metal chelate stabilizer is copper-zinc bimetallic organic complex; the particle size of the oxygen scavenging microcapsule is 2-5μm, and the wall thickness is 0.5-1μm.

4. A process for the preparation of the weatherable composite photoinitiator for outdoor use according to any one of claims 1 to 3, characterized in that, Comprising the following steps: S1, preparing main photoinitiator: under inert gas protection, acylating alpha-hydroxy isobutyryl benzene with t-butyl benzoyl chloride in organic solvent at 80-120℃, then adding transesterification catalyst, carrying out transesterification reaction under the conditions of 120-140℃ and reduced pressure, cooling and crystallizing after reaction, filtering, washing and drying to obtain the modified alpha-hydroxy ketone derivative; S2, preparing stable protection pre-dispersion: dispersing hydrophobic modified nano-silica in alcohol solvent, ultrasonic treatment, adding composite ultraviolet absorber and continuing ultrasonic dispersion, then transferring into high-pressure homogenizer for homogenization, and then adding hindered amine light stabilizer modifier and metal chelate stabilizer, stirring and compounding at 50-60℃ to obtain stable protection pre-dispersion; S3, preparing oxygen scavenging microcapsule: melting ascorbyl palmitate core material and emulsifying in water phase containing emulsifier to form oil-in-water emulsion; simultaneously adding organic solution of isocyanate and aqueous solution of polyamine into the emulsion, carrying out interfacial polymerization reaction under the conditions of 40-50℃ and pH 8-9, centrifuging, washing and drying after reaction to obtain the oxygen scavenging microcapsule; S4, preparing synergistic system: dispersing electron donor-acceptor complex in alcohol solvent, ultrasonic treatment, adding leveling-wetting modifier and continuing ultrasonic dispersion, then transferring into high-pressure homogenizer for homogenization, and then adding oxygen scavenging microcapsule and stirring to obtain the synergistic system. S4, composite blending: the main photoinitiator, stable protective pre-dispersion, electron donor-acceptor complex, oxygen scavenging microcapsule and leveling-wetting modifier are weighed according to the proportion, and are dissolved by stirring under the protection of inert gas to obtain a mixed slurry; S5, fine dispersion and post-treatment: the mixed slurry obtained in step S4 is ground and sand-milled in sequence until the fineness is ≤5μm, then the solvent is removed at 60-70℃ and under vacuum condition, and the obtained molten material is extruded by a twin-screw extruder, underwater pelletized, and dried to obtain a granular outdoor weatherable composite photoinitiator.

5. The preparation method of the outdoor weather-resistant composite photoinitiator according to claim 4, characterized in that, In step S1, the ester exchange catalyst is titanium acid tetraisopropyl ester, and the vacuum degree of the reduced pressure condition is not less than-0.095MPa; in step S2, the pressure of the high-pressure homogenizer is 70-80MPa, and the homogenization times is 3-5 times; in step S3, the isocyanate is isophorone diisocyanate, and the polyamine is ethylenediamine.

6. A photocurable composition, characterized by, The outdoor weatherable composite photoinitiator as claimed in any one of claims 1-3 is used in the light-curable composition.

7. The photocurable composition according to claim 6, characterized in that, The content of the outdoor weatherable composite photoinitiator is 1%-10% based on the total weight of the light-curable composition.

8. An outdoor paint characterized by, The light-curable composition as claimed in claim 6 is made.

9. An outdoor ink, characterized by The light-curable composition as claimed in claim 6 is made.

10. Use of the outdoor weatherable composite photoinitiator as claimed in any one of claims 1-3 in the preparation of outdoor weatherable light-curable materials.

Images