Type I / Type II composite visible triphenylamine oxime ester derivative photoinitiator

Abstract

This invention relates to a Type I / Type II composite visible-light triphenylamine oxime ester photoinitiator. Based on WH-2, this patent introduces phenyl ketone and different electron-donating substituents at the R position of triphenylamine to prepare derivatives including TU-1 (with a methoxy group at the para position), TU-2 (with a third butyl group), TU-3 (with a hydrogen group), and TU-4 (with a methyl group). In addition to comparing their photoreactivity, the feasibility of a Type I and Type II composite triphenylamine oxime ester photoinitiator for visible light wavelengths is also evaluated.

Description

Technical Field

[0001] This invention is a Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator. It is based on triphenylamine oxime ester, with phenyl ketone and its different electron-donating substituents introduced at the R position. By introducing different substituents, it can achieve a tunable visible light absorption band. In addition, the introduction of phenyl ketone can form a Type I / Type II composite photoinitiator to enhance photoinitiation properties. Prior Technology

[0002] Photopolymerization technology refers to the technology that uses energy to cause unsaturated monomers to react under ultraviolet light, visible light, or electron beam irradiation. It is widely used in coatings, adhesives, dental reinforcement materials, 3D printing, semiconductors, and printed circuit boards. Photopolymerization systems can be divided into oligomers, reactive monomers, photoinitiators, and additives according to their applications. The content of photoinitiators is usually 1-5 wt% of the overall formulation. Although the content is small, it has a great influence on the reaction rate. Generally, photoinitiators need to have the following characteristics: (1) the ability to absorb light radiation energy to cause monomers to undergo polymerization; (2) good thermal stability. In addition, the light source is an important factor affecting the reaction of photoinitiators. The reaction process is that after the photoinitiator receives the energy of light, it transforms into an active structure and then carries out subsequent chain reactions. Therefore, the matching between the photoinitiator and the light source has a decisive influence on the photopolymerization efficiency. In recent years, manufacturers have been moving towards converting traditional UV mercury lamps into more environmentally friendly LED light sources or visible light wavelength light sources with bottom penetration effects. Therefore, novel visible light photoinitiators have become a research focus in recent years.

[0003] Photoinitiators can be classified into cationic polymerization (CP) and free radical polymerization (FRP) photocuring systems based on their reaction mechanisms. Free radical photoinitiators are currently widely used in the industry due to their advantages such as fast curing rate, low cost, and no post-curing. The free radical reaction mechanism can be further divided into two categories: Type I (direct cleavage type) and Type II (bimolecular type).

[0004] In Type I photocuring systems, the cleavage of NO bonds, CP bonds, and CC bonds can be mainly divided into three types. Taking the NO bond as an example, when exposed to a suitable light source, the NO bond can be broken to produce imino and acyloxy groups, as shown in Figure 1. The acyloxy groups can further undergo decarboxylation to generate CO2. This process can partially solve the polymerization inhibition caused by atmospheric molecular oxygen (oxygen inhibition). In Type II photocuring systems, the system is mainly composed of a (PI) photoinitiator (commonly known as a hydrogen acceptor) and a (DH) co-initiator (commonly known as a hydrogen donor). As shown in Figure 2, when the photoinitiator (PI) is exposed to light, the molecule transitions from the ground state to the excited state, and then takes a hydrogen atom from the adjacent hydrogen donor (DH), generating free radicals PIH․ and D․. Finally, the D․ free radicals can initiate cross-linking polymerization reactions between reactive monomers and oligomers. In the Type I and Type II composite photocuring system, we can modify the structure to achieve a highly reactive oxime ester photoinitiator that can initiate both Type I and Type II photoinitiators, as shown in Figure 1 with the molecular design of the R 1 functional group. This is also the work done in this patent. Summary of the Invention

[0005] This invention relates to a Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator, wherein the triphenylamine oxime ester derivative has the following general formula (I): (I) Where R is: The aromatic ring structure indicates that the C1 carbon atom is attached to the R carbon atom position in Formula I. Based on WH-2 in Figure 3, this patent introduces phenyl ketone and different electron-donating substituents at the R position of triphenylamine to prepare derivatives, namely TU-1 with a methoxy group at the para position, TU-2 with a third butyl group, TU-3 with a hydrogen group, and TU-4 with a methyl group. In addition to comparing their photoreactivity, the feasibility of Type I and Type II composite triphenylamine oxime ester photoinitiators in the visible light wavelength range is also evaluated. The Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator is a direct cleavage type photoinitiator. Its triphenylamine oxime ester derivative exhibits visible light absorption. Its triphenylamine oxime ester derivative contains a triphenylamine benzophenone structure in its main body. The phenyl ketone structure of the triphenylamine has different electron-donating groups at the para-position, including substituents such as methoxy, methyl, tert-butyl, methylamine, or alkoxy. Furthermore, the triphenylamine oxime ester derivative undergoes photopolymerization with acrylic monomers. The acrylic monomer ester content in the photopolymerization formulation is 40-99 wt%. The photoinitiator content in the photopolymerization formulation is less than or equal to 10 wt%, and the hydrogen preform content is less than or equal to 10 wt%. Furthermore, the photoinitiator of the triphenylamine oxime ester derivative is suitable for exposure wavelengths in the ultraviolet to visible light range. The phenyl ketone structure of the triphenylamine has different electron-donating groups at the para-position, including substituents such as methoxy, methyl, tert-butyl, methylamine, or alkoxy. This invention relates to a Type I / Type II composite visible-light triphenylamine oxime ester derivative photoinitiator. By structurally modifying the oxime ester curing system, a highly reactive composite oxime ester photoinitiator is achieved. This invention differs significantly from prior art, demonstrating its novelty, advancement, and practical benefits. A preferred embodiment and accompanying drawings are provided below for detailed explanation of the techniques, methods, and effects employed in this invention. It is believed that the aforementioned objectives, structure, and features of this invention will be understood in depth and detail from these examples. Simple Explanation of the Diagram

[0006] Figure 1 shows the reaction mechanism of the Type I oxime ester curing system. Figure 2 shows the reaction mechanism of the Type II photoinitiator. Figure 3 shows a schematic diagram of the structures of WH-2, TU-1, TU-2, TU-3 and TU-4 of the present invention. Figure 4 shows the reaction flow chart of TU-1-1. Figure 5 shows the reaction flow chart of TU-1-2. Figure 6 shows the reaction flow chart of TU-1-3. Figure 7 shows the TU-1 reaction flow chart. Figure 8 shows the reaction flow chart of TU-2-1. Figure 9 shows the reaction flow chart of TU-2-2. Figure 10 shows the reaction flow chart of TU-2-3. Figure 11 shows the TU-2 reaction flow chart. Figure 12 shows the reaction flow chart of TU-3-2. Figure 13 shows the reaction flow chart of TU-3-3. Figure 14 shows the TU-3 reaction flow chart. Figure 15 shows the reaction flow chart of TU-4-2. Figure 16 shows the reaction flow chart of TU-4-3. Figure 17 shows the TU-4 reaction flow chart. Figure 18 shows the UV / Vis absorption spectrum of the TU-series. Figure 19 shows the Photo-DSC plots of TU-series and OXE-02 photoinitiators with TMPTA monomers in an LED 365nm light source; (a) heat flow plot, (b) double bond conversion plot. Figure 20 shows the Photo-DSC plots of TU-series and OXE-02 photoinitiators with TMPTA monomers in an LED 405nm light source; (a) heat flow plot, (b) double bond conversion plot. Figure 21 shows the Photo-DSC diagrams of TU-1 photoinitiator with TMPTA as monomer and various hydrogen precursors; (a) heat flow diagram, (b) double bond conversion diagram. Figure 22 shows the reaction mechanism of TU-1 and TU-1 / TEOA. Figure 23 shows the Photo-DSC diagrams of TU-1 photoinitiator with TMPTA as monomer and hydrogen precursors (TEOA) in different weight ratios; (a) heat flow diagram, (b) double bond conversion diagram. Figure 24 shows the 3D printed products of TU-1: (a) a TU-1 letter structure with a thickness of 2.7 mm and (b) a complex configuration of TU-1 screws with a thickness of 6.4 mm. Implementation

[0007] The following describes the implementation of this invention through specific embodiments. Those skilled in the art can easily understand the other advantages and effects of this invention from the content disclosed in this specification. This invention can also be implemented or applied through other different embodiments, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of this invention.

[0008] This invention relates to a Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator, wherein the triphenylamine oxime ester derivative has the following general formula (I): (I) Where R is: The aromatic ring structure indicates the position of the C1 carbon atom attached to the R carbon atom in Formula I. This is a Type I / Type II composite visible-light triphenylamine oxime ester derivative photoinitiator, specifically a direct cleavage type photoinitiator. This triphenylamine oxime ester derivative exhibits visible light absorption. The main body of this triphenylamine oxime ester derivative contains a triphenylamine benzophenone structure. The para-position of the phenyl ketone in this triphenylamine structure has various electron-donating groups, including methoxy, methyl, tert-butyl, methylamine, or alkoxy substituents. Furthermore, this triphenylamine oxime ester derivative undergoes photopolymerization with acrylic monomers. The acrylic monomer content in the photopolymerization formulation is 40-99 wt%. The photoinitiator content in the photopolymerization formulation is less than or equal to 10 wt%, and the hydrogen preform content in the photopolymerization formulation is less than or equal to 10 wt%. Furthermore, the photoinitiator of this triphenylamine oxime ester derivative is suitable for exposure wavelengths in the ultraviolet to visible light range. The phenyl ketone structure of the triphenylamine has different electron-donating groups at the para-position, including methoxy, methyl, tert-butyl, methylamine, or alkoxy substituents. In this patent embodiment, based on WH-2 in Figure 3, phenyl ketone and its para-position containing different electron-donating substituents were introduced at the R position of the triphenylamine to prepare derivatives TU-1 with a methoxy group at the para-position, TU-2 with a tert-butyl group, TU-3 with a hydrogen group, and TU-4 with a methyl group. In addition to comparing their photoreactivity characteristics, the feasibility of Type I and Type II composite triphenylamine oxime ester photoinitiators for visible light wavelengths was also evaluated.

[0009] The synthesis steps of the TU-1 series are as follows: First, please refer to Figure 4 for the synthesis of TU-1-1. Under N2, 4-methoxybenzoyl chloride (1 mmol) and zinc chloride (1.2 mmol) are added to a round-bottom flask containing triphenylamine (1.1 mmol). The mixture is stirred at room temperature for 10 minutes. Then, dichloromethane is added to the round-bottom flask as a solvent, and the mixture is refluxed (60 °C) and stirred continuously for 24 hours. After the reaction, the mixture is extracted three times with dichloromethane, and the organic layer is collected. Anhydrous magnesium sulfate is added to remove water from the solution. After filtration, the solvent is removed by vacuum concentration. The product is purified by column chromatography (n-Hexane:DCM = 2:1 as the eluent) to obtain a yellow powder product with a yield of 45%. For the subsequent reaction procedure, please refer to Figure 5 for the synthesis of TU-1-2. Under N2, TU-1-1 (1 mmol) and zinc chloride (1.2 mmol) were added to a round-bottom flask containing valeroyl chloride (1.1 mmol), stirred at room temperature for 10 minutes, and then dichloromethane was added to the round-bottom flask as solvent. The mixture was refluxed (60 °C) and stirred continuously for 24 hours. After the reaction, the mixture was extracted three times with dichloromethane, and the organic layer was collected. Anhydrous magnesium sulfate was added to remove water from the solution. After filtration, the solvent was removed by vacuum concentration. The product was purified by column chromatography (n-Hexane : EA = 6 : 1 as the eluent) to obtain a yellow powder with a yield of 48%. For the subsequent reaction procedure, please refer to Figure 6 for the synthesis of TU-1-3. Under N2, hydroxylamine hydrochloride (1.5 mmol) and anhydrous sodium acetate (1.5 mmol) were added to an ethanol solution containing TU-1-2 (1 mmol), refluxed (80 °C) and stirred for 2 hours, then extracted three times with dichloromethane, the organic layer was collected, and anhydrous magnesium sulfate was added to remove water from the solution. After filtration, the solvent was removed by vacuum concentration to obtain a yellow powder compound. The final reaction procedure is shown in Figure 7 for the synthesis of TU-1. TU-1-3 (1 mmol), acetyl chloride (1 mmol), and TEA (3.5 mmol) were added to a round-bottom flask. Dichloromethane was used as the solvent, and the mixture was stirred at room temperature for 2 hours. The mixture was extracted with DCM / water and ammonium chloride aqueous solution. The organic layer was collected, dehydrated with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum concentration. The product was purified by column chromatography (n-Hexane:DCM = 5:1 as the eluent) to obtain a yellow solid with a yield of 22%.1H-NMR (400 MHz, CDCl3, δ, ppm): 7.829–7.807 (d, 2H, J = 8.8 Hz, Ar–H), 7.702–7.680 (d, 2H, J = 8.8 Hz, Ar–H), 7.653–7.630 (d, 2H, J = 8.8 Hz, Ar–H), 7.363–7.319 (2H, Ar–H), 7.187–7.079 (7H, Ar–H), 6.975–6.953 (d, 2H, J = 8.8 Hz, Ar–H), 3.885 (s, 3H, -OCH3), 2.836–2.797 (2H, -CH2), 2.256 (s, 3H, -OCH 3), 1.611 – 1.535 (2H, -CH 2), 1.462 – 1.389 (2H, -CH 2), 0.966 – 0.929 (3H, -CH 3). FT-Mass (m / z) calcd. 543.22543, found 543.22571。 。

[0010] The synthesis steps for the TU-2 series are as follows: First, refer to the synthesis of TU-2-1 shown in Figure 8. Under N2, 4-tert-buyylbenzoyl chloride (1 mmol) and zinc chloride (1.2 mmol) are added to a round-bottom flask containing triphenylamine (1.1 mmol). The mixture is stirred at room temperature for 10 minutes. Then, dichloromethane is added to the round-bottom flask as a solvent, and the mixture is refluxed (60 °C) and stirred continuously for 24 hours. After the reaction, the mixture is extracted three times with dichloromethane, and the organic layer is collected. Anhydrous magnesium sulfate is added to remove water from the solution. After filtration, the solvent is removed by vacuum concentration. The product is purified by column chromatography (n-Hexane:DCM = 1:1 as the eluent) to obtain a yellow powder product with a yield of 45%. For the subsequent reaction procedure, please refer to Figure 9 for the synthesis of TU-2-2. Under N2, TU-2-1 (1 mmol) and zinc chloride (1.2 mmol) were added to a round-bottom flask containing valeroyl chloride (1.1 mmol), stirred at room temperature for 10 minutes, and then dichloromethane was added to the round-bottom flask as solvent. The mixture was refluxed (60 °C) and stirred continuously for 24 hours. After the reaction, the mixture was extracted three times with dichloromethane, and the organic layer was collected. Anhydrous magnesium sulfate was added to remove water from the solution. After filtration, the solvent was removed by vacuum concentration. The product was purified by column chromatography (n-Hexane:DCM = 3:1 as the eluent) to obtain a yellow powder product with a yield of 43%. For the subsequent reaction procedure, please refer to Figure 10 for the synthesis of TU-2-3. Under N2, hydroxylamine hydrochloride (1.5 mmol) and anhydrous sodium acetate (1.5 mmol) were added to an ethanol solution containing TU-2-2 (1 mmol), refluxed (80 °C) and stirred for 2 hours, then extracted three times with dichloromethane, the organic layer was collected, and anhydrous magnesium sulfate was added to remove water from the solution. After filtration, the solvent was removed by vacuum concentration to obtain a yellow colloidal compound with a yield of 85%. For the final reaction procedure, please refer to Figure 11 to complete the synthesis of TU-2. TU-2-3 (1 mmol), acetyl chloride (1 mmol), and TEA (3.5 mmol) were added to a round-bottom flask. Dichloromethane was used as the solvent, and the mixture was stirred at room temperature for 2 hours. Extraction was performed with DCM / water and ammonium chloride aqueous solution. The organic layer was collected, dehydrated with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum concentration. The product was purified by column chromatography (n-Hexane:DCM = 3:1 as the eluent) to obtain a yellow colloid with a yield of 26%.1H-NMR (400 MHz, CDCl 3, δ, ppm): 7.751 – 7.722 (4H, Ar–H), 7.654 – 7.632 (2H, Ar–H), 7.496 – 7.475 (2H, Ar–H), 7.366 – 7.327 (2H, Ar–H), 7.191 – 7.072 (7H, Ar–H), 2.837 – 2.798 (2H, -CH2), 2.257 (s, 3H, -CH 3), 1.445 – 1.426 (4H, -CH 2), 1.413 – 1.389 (9H, -CH 3), 0.966 – 0.930 (3H, -CH 3). FT-Mass (m / z) calcd. 569.27746, found 569.27740。 。

[0011] For the synthesis of the TU-3 series, please refer to Figure 12 for the synthesis of TU-3-2. Under N2 conditions, add WH-2-1 (1 mmol) and zinc chloride (2 mmol) to a round-bottom flask containing benzoyl chloride (2 mmol), stir at room temperature for 10 minutes, then add dichloromethane as solvent to the round-bottom flask, reflux (60 °C) and stir continuously for 24 hours. After the reaction, extract three times with DCM, collect the organic layer, add anhydrous magnesium sulfate to remove water from the solution, filter, and remove the solvent by vacuum concentration. The product is purified by column chromatography (n-Hexane:DCM = 3:1 as the eluent) to obtain a yellow powder product with a yield of 30%. For the subsequent reaction procedure, please refer to Figure 13 for the synthesis of TU-3-3. Under N2, hydroxylamine hydrochloride (1.5 mmol) and anhydrous sodium acetate (1.5 mmol) were added to an ethanol solution containing TU-3-2 (1 mmol), refluxed (80 °C) and stirred for 2 hours, then extracted three times with DCM, the organic layer was collected, and anhydrous magnesium sulfate was added to remove water from the solution. After filtration, the solvent was removed by vacuum concentration to obtain a yellow colloidal compound. For the final reaction procedure, please refer to Figure 14 to complete the synthesis of TU-3. TU-3-3 (1 mmol), acetyl chloride (1 mmol), and TEA (3.5 mmol) were added to a round-bottom flask. Dichloromethane was used as the solvent, and the mixture was stirred at room temperature for 2 hours. Extraction was performed with DCM / water and ammonium chloride aqueous solution. The organic layer was collected, dehydrated with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum concentration. The product was purified by column chromatography (n-Hexane:DCM = 5:1 as the eluent) to obtain a yellow colloid with a yield of 36%.1H-NMR (400 MHz, CDCl3, δ, ppm): 7.793–7.769 (2H, Ar–H), 7.742–7.720 (d, 2H, J = 8.8 Hz, Ar–H), 7.659–7.637 (d, 2H, J = 8.8 Hz, Ar–H), 7.584–7.540 (1H, Ar–H), 7.491–7.452 (1H, Ar–H), 7.370–7.331 (2H, Ar–H), 7.200–7.072 (8H, Ar–H), 2.838–2.798 (2H, -CH2), 2.257 (s, 3H, -CH3), 1.613– 1.537 (2H, -CH 2), 1.463 – 1.390 (2H, -CH 2), 0.966 – 0.930 (3H, -CH 3). FT-Mass (m / z) calcd. 513.21486, found 513.21472。 。

[0012] For the synthesis of the TU-4 series, please refer to Figure 15 for the synthesis of TU-4-2. Under N2 conditions, add WH-2-1 (1 mmol) and zinc chloride (2 mmol) to a round-bottom flask containing 4-methylbenzoyl chloride (2.5 mmol), stir at room temperature for 10 minutes, then add dichloromethane as solvent to the round-bottom flask, reflux (60 °C) and stir continuously for 24 hours. After the reaction, cool to (30 °C), extract three times with DCM, collect the organic layer, add anhydrous magnesium sulfate to remove water from the solution, filter, and remove the solvent by vacuum concentration. The product is purified by column chromatography (n-Hexane : DCM = 1 : 1 as the eluent) to obtain a yellow powder product with a yield of 28%. For the subsequent reaction procedure, please refer to Figure 16 for the synthesis of TU-4-3. Under N2, hydroxylamine hydrochloride (1.5 mmol) and anhydrous sodium acetate (1.5 mmol) were added to an ethanol solution containing TU-4-2 (1 mmol), refluxed (80 °C) and stirred for 2 hours, then extracted three times with DCM, the organic layer was collected, and anhydrous magnesium sulfate was added to remove water from the solution. After filtration, the solvent was removed by vacuum concentration to obtain a yellow colloidal compound. For the final reaction procedure, please refer to Figure 17 to complete the synthesis of TU-4. TU-4-3 (1 mmol), acetyl chloride (1 mmol), and TEA (3.5 mmol) were added to a round-bottom flask. Dichloromethane was used as the solvent, and the mixture was stirred at room temperature for 2 hours. Extraction was performed with DCM / water and ammonium chloride aqueous solution. The organic layer was collected, dehydrated with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum concentration. The product was purified by column chromatography (n-Hexane:DCM = 3:1 as the eluent) to obtain a yellow colloid with a yield of 18%.1H-NMR (400 MHz, CDCl 3, δ, ppm): 7.725 – 7.694 (3H, Ar–H), 7.645 – 7.632 (d, 2H, J = 8.8 Hz, Ar–H), 7.336 – 7.283 (5H, Ar–H), 7.191 – 7.053 (7H, Ar–H), 2.836 – 2.797 (2H, -CH 2), 2.435 (s, 3H, -CH 3), 2.257 (s, 3H, -CH 3), 1.594 – 1.536 (2H, -CH 2), 1.445 – 1.389 (2H, -CH 2), 0.966 – 0.879 (3H, -CH 3). FT-Mass (m / z) calcd. 505.24857, found 505.2485. .

[0013] The UV / Vis spectra of the TU-series were measured using dichloromethane as a solvent at a concentration of 10⁻⁵ M. The UV / Vis spectra are shown in Figure 18, and the results are summarized in Table 1. It can be seen that the absorption band is between 250 and 430 nm. It can be observed that introducing a triphenylamine phenyl ketone derivative at the R₁ position can improve the red shift of the maximum absorption peak and the molar extinction coefficient. The molar extinction coefficients, from largest to smallest, are TU-1 > TU-4 > TU-2 > TU-3. Notably, the methoxylated TU-1 has the highest molar extinction coefficient, which is 2.5 times higher than that of the hydrogen-containing TU-3. Table 1 Absorption Light Data Sample λ (nm) (ε max*10 4M -1cm -1) a,b TU-1 333 (4.13), 369 (5.73) TU-2 334 (2.23), 374 (3.23) TU-3 331 (2.20), 375 (3.00) TU-4 333 (2.99), 373 (4.20) Sample a was dissolved in DCM at a concentration of 10⁻⁵ M. b is expressed in parentheses as the molar extinction coefficient, representing absorbance.

[0014] The photopolymerization characteristics of the TU-series were analyzed using Photo-DSC to measure the heat of reaction released during the curing process. The conversion rate of photopolymerization was then calculated using the formula C = ΔHt / H theor, where C is the photopolymerization conversion rate, ΔHt is the heat of reaction at time t, and H theor is the theoretical exothermic value of the reactive monomer. In the photopolymerization reaction, TMPTA was used as the reactive monomer. The theoretical exothermic value of an acrylic structure is about 86 kJ mol-1. The formulation was photocured by irradiation with an LED 365nm light source at 50 mW cm-2. The monomer TMPTA in the formulation was 98 wt%, and the photoinitiator was 2 wt%. The results are shown in Figure 19 and summarized in Table 2. The final double bond conversion rate was OXE-02 (37%) > TU-1 (33%) = TU-2 (32%) > TU-3 (23%) > TU-4 (8%). The TU series was generally worse than the commercially available OXE-02. This may be because the excessive absorption caused the surface to cure rapidly, so that the uncured part inside continued to affect the heat flow rate. Table 2 Photo-DSC Result Data Table a PI b Conversion (%) ΔHt (kJ / mol) c H max (mW / mg) d Rp max (s -1) e T max (s) f TU-1 33 84 75 0.78 17 TU-2 33 85 62 0.47 16 TU-3 twenty three 58 42 0.32 15 TU-4 8 twenty one 33 0.24 15 OXE-02 37 96 368 2.82 17 a. Measured for 6 minutes using a 50 mW cm⁻² LED lamp (λ: 365 nm). bPhoto-DSC measures PIs / TMPTA weight percentage: PIs : TMPTA = 2 : 98. c.ΔHt is the total enthalpy of reaction over 5 minutes. dH max: Maximum heat flux. e.Rp max: Maximum polymerization rate. fT max: The time of maximum heat flux.

[0015] To demonstrate the significant surface polymerization benefits of the TU series at shorter wavelengths, irradiation was also performed using an LED at 405 nm (50 mW cm⁻²). The results are shown in Figure 20 and summarized in Table 3. The final double bond conversion rates were: TU-1 (46%) = OXE-02 (46%) = WH-2 (46%) > TU-2 (43%) > TU-3 (36%) > TU-4 (31%). At the same intensity of 50 mW cm⁻², the LED at 405 nm performed better than the LED at 365 nm. This is because longer wavelengths improve penetration, allowing for more complete initiation of the photopolymerization system. Furthermore, the conversion rate of TU-1 increased from 33% (LED at 365 nm) to 46% (LED at 405 nm). Under these conditions, higher double bond conversion rates, shorter maximum heat flux times, and polymerization rates were observed, enabling the overall formulation to reach the monomer polymerization peak more quickly. Introducing methoxy groups at the R position helps improve photoreactivity. Table 3 Photo-DSC Result Data Table a PI b Conversion (%) ΔHt (kJ / mol) c H max (mW / mg) d Rp max (s -1) e T max (s) f TU-1 46 118 320 2.43 15 TU-2 43 112 254 1.94 16 TU-3 36 92 139 1.07 16 TU-4 31 80 100 0.77 17 OXE-02 46 119 375 2.84 20 a. Measured for 6 minutes using a 50 mW cm⁻² LED lamp (λ: 405 nm). bPhoto-DSC measures PIs / TMPTA weight percentage: PIs : TMPTA = 2 : 98. c.ΔHt is the total enthalpy of reaction over 5 minutes. dH max: Maximum heat flux. e.Rp max: Maximum polymerization rate. fT max: The time of maximum heat flux.

[0016] Because TU-1 exhibits the best overall performance and its structure contains a phenyl ketone that can act as a hydrogen acceptor, it was studied for photopolymerization with different hydrogen preforms (TEOA, TEA, EDB, NPG) at the same weight ratio under LED@405 nm (50 mW cm⁻²) to make it a Type I / Type II composite photoinitiator. The results are shown in Figure 21 and summarized in Table 4. The final double bond conversion rates were TU-1 / TEOA (50%) > TU-1 / TEA (47%) > TU-1 / EDB (44%) > TU-1 / NPG (23%). It can be seen that TU-1 / TEOA with added hydrogen preforms is the best formulation in the composite system in terms of final conversion rate, maximum heat flux, and maximum polymerization rate. Furthermore, it is also higher than TU-1 without added hydrogen preforms. Furthermore, although the TU-1 / TEA system exhibits better reactivity than TU-1, the toxicity and odor of TEA limit its industrial application. Therefore, we will choose TEOA as the hydrogen preform for subsequent photopolymerization tests. TEOA possesses both hydroxyl and amino groups, effectively capturing and stabilizing free radicals, promoting polymerization. Its low toxicity also makes it more advantageous in practical applications. With the introduction of the TEOA hydrogen preform, the TU-1 photoinitiator, upon irradiation, not only generates free radicals from the cleavage of the NO bond in the oxime ester, but also undergoes a hydrogen abstraction reaction between the phenyl ketone (hydrogen acceptor) and TEOA (hydrogen preform), leading to the generation of further polymerizable free radicals in TEOA. This increases the free radical concentration and enhances the overall photopolymerization capability. The reaction mechanism of TU-1 and TU-1 / TEOA is shown in Figure 22. Table 4 Photo-DSC Results Data Table a PI b Conversion (%) ΔHt (kJ / mol) c H max (mW / mg) d Rp max (s -1) e T max (s) f TU-1 / TEOA 50 129 507 3.86 16 TU-1 / TEA 47 121 507 3.89 16 TU-1 / EDB 44 114 304 2.33 19 TU-1 / NPG twenty three 59 125 0.94 16 a. Measured for 6 minutes using a 50 mW cm⁻² LED lamp (λ: 405 nm). bPhoto-DSC measures the weight percentage of TU-1 / RH: TU-1 / RH / TMPTA (1 / 1 / 98wt%). c.ΔHt is the total enthalpy of reaction over 5 minutes. dH max: Maximum heat flux. e.Rp max: Maximum polymerization rate. fT max: The time of maximum heat flux.

[0017] The effects of TU-1 and TEOA at different weight ratios were investigated using an LED at 405 nm (50 mW cm⁻²) light source. The results are shown in Figure 23 and summarized in Table 5. The TU-1 / TEOA weight ratios (w / w) of 1:1, 1:2, 1:4, and 1:8 yielded final conversion rates of 50%, 41%, 45%, and 44%, respectively; maximum heat fluxes of 129, 105, 115, and 114 mW mg⁻¹; and maximum polymerization rates of 3.86, 2.63, 2.50, and 2.69 s⁻¹. These results indicate that even lower concentrations of TEOA can achieve good double bond conversion and polymerization rates. Therefore, it can be seen that the addition of RH to TU-1, regardless of the weight ratio or the addition of different RH preforms, results in the best performance with TU-1 / TEOA (1 / 1) (w / w). Table 5 Photo-DSC Results Data Table a PI / RH Conversion (%) ΔHt (kJ / mol) b H max (mW / mg) c Rp max (s -1) d T max (s) e TU-1 / TEOA (1:1) 50 129 507 3.86 16 TU-1 / TEOA (1:2) 41 105 344 2.63 17 TU-1 / TEOA (1:4) 45 115 328 2.50 17 TU-1 / TEOA (1:8) 44 114 347 2.69 17 a. Measure for 6 minutes using a 50 mW cm⁻² LED lamp (λ: 405 nm). b. ΔHt is the total enthalpy of the reaction over 5 minutes. cH max: Maximum heat flux. d.Rp max: Maximum polymerization rate. eT max: The time of maximum heat flow.

[0018] In photocurable 3D printing experiments, TU-1 from the TU-series was mixed with 9EO-TMPTA at 1 wt% to form a resin for 3D printing. The first result, as shown in Figure 24(a), is a printed 3D text, approximately 3.4 cm in length and 2.7 mm in thickness, with a complete outline. The entire sample was printed in about one hour. Furthermore, to explore its suitability as a photoinitiator for 3D printing, complex and intricate patterns were used for 3D printing, such as the screw configuration shown in Figures 24(b)-(d), approximately 3.6 cm in length and 6.4 mm in thickness. This also demonstrated good resolution and no obvious defects or imperfections in appearance.

[0019] This invention relates to the use of a Type I / Type II composite visible-light triphenylamine oxime ester derivative photoinitiator. Structural modification is performed in an oxime ester curing system to achieve a highly reactive oxime ester composite photoinitiator. This differs from prior art, demonstrating novelty, progress, and practical benefits. Therefore, it effectively addresses the shortcomings of conventional techniques and has considerable practical applicability. In summary, the specific structure disclosed in the embodiments of this invention indeed provides an application as a visible-light photoinitiator. Its overall chemical structure has not been seen in similar products and was not disclosed prior to this application, thus meeting the statutory requirements of patent law. Therefore, this invention patent application is filed in accordance with the law.

[0020] However, the above description is only one preferred embodiment of this invention and should not be construed as limiting the scope of this invention. All equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the invention specification should still fall within the scope of this invention.

[0021] none

Claims

1. A Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator, wherein the triphenylamine oxime ester derivative has the following general formula (I): (I) Wherein, R is: The position of the C1 carbon atom attached to the R carbon atom in Formula I in the aromatic ring structure.

2. The Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator as described in claim 1, wherein the triphenylamine oxime ester derivative is a direct cleavage type photoinitiator.

3. The Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator as described in claim 1, wherein the triphenylamine oxime ester derivative has the characteristic of absorbing visible light.

4. The Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator as described in claim 1, further comprising photopolymerization of the triphenylamine oxime ester derivative with an acrylic monomer.

5. The Type I / Type II composite visible light triphenylamine oxime ester derivative photoinitiator as described in claim 4, wherein the acrylic monomer content in the formulation of the photopolymerization reaction is 40-99 wt.

6. The Type I / Type II composite visible triphenylamine oxime ester derivative photoinitiator as described in claim 1, further wherein the exposure wavelength of the triphenylamine oxime ester derivative photoinitiator is applicable to the ultraviolet to visible light range.

Images