A photoinitiator, its preparation method and application

Abstract

The present application relates to a kind of photoinitiator and its preparation method and application, the photoinitiator includes 2,4,6-trimethyl benzoyl phenyl methyl phosphonate, the melting point of the photoinitiator is 53-57 ℃.The photoinitiator described in the present application has the characteristics of light color, low yellowness, little smell, good fluidity and high storage stability, and has good solubility in monomer, can also play the role of dispersant, the curing rate of the photo-curing system formed is fast, the adhesion on the surface of different plastic substrates is high, and the comprehensive performance is excellent.

Description

Technical Field

[0001] This invention relates to the field of photoinitiator technology, and in particular to a photoinitiator, its preparation method, and its application. Background Technology

[0002] Photoinitiators, also known as photosensitizers or photocuring agents, are compounds that can absorb energy of a certain wavelength in the ultraviolet (250–420 nm) or visible (400–800 nm) region, generate free radicals, cations, etc., and thus initiate monomer polymerization, cross-linking, and curing.

[0003] Photoinitiators are classified into two main categories according to their photolysis mechanism: free radical polymerization photoinitiators and cationic polymerization photoinitiators, with free radical photoinitiators being the most widely used. Free radical photoinitiators can be further classified into cleavage-type photoinitiators and hydrogen-abstraction-type photoinitiators according to their mechanism of free radical generation. An ideal photoinitiator should have the following advantages: (1) low cost and simple synthesis; (2) the photoinitiator and its photolysis products should be non-toxic and odorless; (3) good stability and easy to store for a long time; (4) the absorption spectrum of the photoinitiator must match the emission spectrum of the radiation source and have a high molar extinction coefficient; and (5) high initiation efficiency.

[0004] However, due to reproductive toxicity issues, current mature photoinitiators such as photoinitiator 907, photoinitiator 369 and photoinitiator 379 are further regulated by the EU REACH regulation, resulting in a further reduction in the types of photoinitiators with excellent overall performance. Therefore, it is crucial to develop a photoinitiator with excellent overall performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a photoinitiator, its preparation method, and its application. The photoinitiator is characterized by its light color, low yellowness value, low odor, good fluidity, and high storage stability. Furthermore, it exhibits good solubility in monomers and can also function as a dispersant. The resulting photocurable system has a fast curing rate, high adhesion to various plastic substrates, and excellent overall performance.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a photoinitiator comprising methyl 2,4,6-trimethylbenzoylphenylphosphonate;

[0008] The photoinitiator has a melting point of 53-57℃, such as 53.5℃, 54℃, 54.5℃, 55℃, 55.5℃, 56℃, 56.5℃, etc.

[0009] In this invention, the photoinitiator has the characteristics of light color, low yellowness value, low odor, good fluidity and high stability. It has good solubility in monomers, the photocurable system formed has a fast curing rate, high adhesion to different plastic substrates, and excellent overall performance.

[0010] In addition to its excellent photoinitiating properties, the photoinitiator described in this invention also functions as a dispersant. In photocurable compositions, the photoinitiator described in this invention can reduce the amount of dispersant used, save costs, and reduce the adverse effects of excessive additives on the system.

[0011] Preferably, the morphology of the photoinitiator includes any one or a combination of at least two of the following: cross-shaped, spherical, quasi-spherical, or sheet-like. Typical but non-limiting combinations include: a combination of cross-shaped and spherical, a combination of spherical, quasi-spherical, and sheet-like, a combination of cross-shaped, spherical, quasi-spherical, and sheet-like, etc., with a cross-shaped morphology being more preferred.

[0012] Preferably, the intersecting shape includes a through-type intersecting shape or a non-through-type intersecting shape.

[0013] Preferably, the cross shape consists of at least two regular and / or irregular columnar intersections.

[0014] In this invention, typical but non-limiting examples of the columnar shape include cuboids, cubes, prisms, cylinders, and cylinder-like structures.

[0015] In this invention, the morphology of the photoinitiator is preferably as described above. The photoinitiator with the above morphology has good stability, better compatibility with other components in the photocurable composition, can better play the role of dispersant, and the resulting photocurable composition has a fast curing rate, high adhesion to different plastic substrates, and excellent overall performance.

[0016] Preferably, the particle size distribution of the photoinitiator is: D50 of 40-80 μm (e.g., 42 μm, 45 μm, 52 μm, 54 μm, 56 μm, 58 μm, 60 μm, 62 μm, 64 μm, 66 μm, 68 μm, 70 μm, 72 μm, 75 μm, 78 μm, etc.).

[0017] In this invention, D50 refers to the particle size at a point representing 50% of the total volume of the particles, based on the cumulative degree distribution curve of the particle size, with the total volume of the particles being 100%. The testing method used includes laser diffraction scattering. D99 is similar.

[0018] In this invention, the reason for controlling the particle size distribution of the photoinitiator within a preferred range is that the interaction forces between the photoinitiator particles within this range are well balanced, allowing the photoinitiator itself to perform at its best. When applied to a photocurable composition, it can better play the role of a dispersant, has strong compatibility with other components, and exhibits excellent overall performance. If the particle size is too small, it is easy to generate dust and static electricity, requiring high-end equipment and being inconvenient to use. Moreover, the larger particle size results in a larger specific surface area, reduced storage stability, shorter shelf life, and reduced effective utilization of raw materials. If the particle size is too large, it has poor flowability and poor solubility in monomers, making it difficult to play the role of a dispersant effectively. This results in a slow curing rate of the formed photocurable system and poor adhesion to different plastic substrates.

[0019] In this invention, the morphology and particle size distribution of the photoinitiator are coordinated to further improve the overall performance of the photoinitiator.

[0020] Preferably, the photoinitiator has a D99 ≤ 150 μm, such as 145 μm, 140 μm, 135 μm, 130 μm, 120 μm, 115 μm, etc.

[0021] Preferably, the molar extinction coefficient of the photoinitiator is 200-2500 L·mol⁻¹. -1 ·cm -1 For example, 400 L·mol -1 ·cm -1 600 L·mol -1 ·cm -1 800 L·mol -1 ·cm -1 1000L·mol -1 ·cm -1 1200 L·mol -1 ·cm -1 1400 L·mol -1 ·cm -1 1600 L·mol -1 ·cm -1 2000 L·mol -1 ·cm -1 2200 L·mol -1 ·cm -1 2400 L·mol -1 ·cm -1 wait.

[0022] In this invention, the method for testing the molar extinction coefficient is as follows: A photoinitiator is dissolved in a solvent (including but not limited to methylcyclohexane) to prepare a 1 mol / L solution. The solution is placed in a cuvette, and the UV absorbance of the solution in the range of 200 nm to 500 nm (e.g., 250 nm, 270 nm, 290 nm, 370 nm, etc.) is measured using a UV spectrophotometer. The molar extinction coefficient at different wavelengths is calculated using Formula 1.

[0023] A = ε·l·c Formula 1

[0024] Where A is absorbance; ε is the molar extinction coefficient, with units of L·mol⁻¹. -1 ·cm -1 ; l is the optical path length, - here is taken as 1 cm; c is the concentration, here is taken as 1 mol / L.

[0025] For example, at a wavelength of 270 nm, the molar extinction coefficient of the photoinitiator is 2380-2440 L·mol⁻¹. -1 ·cm -1 For example, 2385 L·mol -1 ·cm -1 2391 L·mol -1 ·cm -1 2395 L·mol -1 ·cm -1 2400 L·mol -1 ·cm -1 2410 L·mol -1 ·cm -1 2420 L·mol -1 ·cm -1 2430 L·mol -1 ·cm -1 wait.

[0026] For example, at a wavelength of 290 nm, the molar extinction coefficient of the photoinitiator is 2160-2210 L·mol⁻¹. -1 ·cm -1 For example, 2165 L·mol -1 ·cm -1 2170 L·mol -1 ·cm -1 2180 L·mol -1 ·cm -1 2190 L·mol -1 ·cm -1 2200 L·mol -1 ·cm -1 wait.

[0027] For example, at a wavelength of 370 nm, the molar extinction coefficient of the photoinitiator is 285-295 L·mol⁻¹. -1 ·cm -1 For example, 286 L·mol -1 ·cm -1 287 L·mol -1 ·cm -1 288 L·mol -1 ·cm -1 289 L·mol -1 ·cm -1 291 L·mol -1 ·cm -1 292 L·mol -1 ·cm -1 293 L·mol -1 ·cm -1 294 L·mol -1 ·cm -1 wait.

[0028] In this invention, the molar extinction coefficient of the photoinitiator is controlled within the specified range because the photoinitiator within the specified range has the characteristics of light color, low yellowness value, low odor, good fluidity and high storage stability, and good solubility in monomers. Furthermore, the photocurable composition formed therefrom has a fast curing rate, high adhesion to different plastic substrates, and excellent overall performance.

[0029] In a second aspect, the present invention provides a method for preparing the photoinitiator described in the first aspect, the method comprising the following steps:

[0030] The photoinitiator was obtained by mixing dimethylphenylphosphonate and 2,4,6-trimethylbenzoyl chloride, reacting and melting crystallizing.

[0031] Preferably, the reaction temperature is 40-60℃, such as 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃, etc.

[0032] Preferably, the reaction time is 1-3 hours, such as 1.2 hours, 1.4 hours, 0.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, etc.

[0033] Preferably, the melting and crystallization process includes melting, crystallization, sweating, and melting.

[0034] Preferably, the melting process includes heating and holding operations.

[0035] Preferably, the temperature is raised to 60-65°C, such as 61°C, 62°C, 63°C, 64°C, etc.

[0036] Preferably, the heat preservation time is 30-60 minutes, such as 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, etc.

[0037] Preferably, the crystallization is carried out in a crystallization apparatus, the structure of which is shown in the schematic diagram below. Figure 7 As shown, the crystallization device includes a crystallization tank 2, an outer jacket 3 disposed on the outer surface of the crystallization tank, and an inner jacket 1 disposed inside the crystallization tank; the crystallization device also includes a liquid outlet 4.

[0038] In this invention, the liquid outlet is used to discharge the reaction liquid, product or by-product in the reaction as needed, and the number of liquid outlets is set as needed, for example, 1-3.

[0039] In this invention, the crystallization device also includes auxiliary units such as a temperature control system, which are not shown in the schematic diagram and are provided as needed.

[0040] Preferably, during crystallization, the reaction solution is placed in a crystallization tank, the temperature of the outer jacket is controlled, and the temperature of the inner jacket is adjusted for the first time to carry out crystallization.

[0041] Preferably, the temperature of the outer jacket is controlled to 40-60°C, such as 45°C, 50°C, 55°C, etc.

[0042] Preferably, the temperature of the inner jacket is adjusted to 10-45°C for the first time, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc., and more preferably 35-45°C.

[0043] In this invention, controlling the temperature of the inner jacket during the first adjustment is within a preferred range, which is beneficial for forming a photoinitiator with a particle size within a preferred range and a cross-shaped morphology.

[0044] Preferably, the time taken for the first adjustment of the inner jacket to the specified temperature is 30-120 minutes, such as 40 minutes, 60 minutes, 80 minutes, 100 minutes, etc.

[0045] Preferably, after the inner jacket is adjusted to the temperature for the first time, it is maintained for 30-240 minutes, such as 40 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, 200 minutes, 220 minutes, etc.

[0046] Preferably, the sweating process includes discharging the reaction liquid after crystallization, adjusting the temperature of the inner jacket a second time, and reducing pressure.

[0047] Preferably, the second adjustment of the inner jacket temperature is set to 10-50°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, etc., and more preferably 37-50°C.

[0048] In this invention, controlling the temperature of the inner jacket during the second adjustment within a preferred range is beneficial for forming a photoinitiator with a particle size within a preferred range and a cross-shaped morphology.

[0049] Preferably, the time taken for the second adjustment of the inner jacket to the specified temperature is 30-240 minutes, such as 40 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, 200 minutes, 220 minutes, etc.

[0050] Preferably, after adjusting the inner jacket to the temperature for the second time, it is maintained for 30-240 minutes, such as 40 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, 200 minutes, 220 minutes, etc.

[0051] Preferably, the pressure is reduced to 0.01-0.1 MPa, for example, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, etc.

[0052] Preferably, after the pressure is reduced to 0.01-0.1 MPa (e.g., 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, etc.), it is maintained for 30-240 minutes, such as 40 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes, 180 minutes, 200 minutes, 220 minutes, etc.

[0053] Preferably, after sweating, the crystals on the surface of the inner jacket are collected and melted.

[0054] Preferably, the melting temperature is 60-65℃, such as 61℃, 62℃, 63℃, 64℃, etc.

[0055] Preferably, the process after melt crystallization further includes solvation treatment and drying.

[0056] Preferably, the solvation treatment includes dissolving the material in a good solvent and then precipitating it in a poor solvent.

[0057] In this invention, a good solvent refers to a solvent that has good solubility in the molten crystallized material. The criterion for this is that when the material and a good solvent are mixed at a mass ratio of 1:2 at 30°C, the mixture can be completely dissolved within half an hour. A poor solvent refers to a solvent that has poor solubility in the molten crystallized material. The criterion for this is that when the material and a good solvent are mixed at a mass ratio of 1:10 at 30°C, the mixture cannot be completely dissolved within half an hour.

[0058] Preferably, the mass of the good solvent is 25%-45% based on 100% of the mass of the material after melting and crystallization, for example, 25%, 30%, 35%, 40%, 45%, etc.

[0059] In this invention, taking the mass of the melted and crystallized material as 100%, the mass of the good solvent is controlled within a preferred range, which is beneficial to forming a photoinitiator with a particle size within a preferred range and a cross-shaped morphology.

[0060] Preferably, the mass ratio of the good solvent to the poor solvent is 1:(1-10), where 1-10 can be 2, 4, 6, 8, etc., and more preferably 1:(1-5).

[0061] In this invention, controlling the mass ratio of the good solvent to the bad solvent within a preferred range is beneficial for forming a photoinitiator with a particle size within a preferred range and a cross-shaped morphology.

[0062] Preferably, the good solvent includes any one or a combination of at least two of toluene, methanol, ethyl acetate, butyl acetate, isopropyl acetate, or n-propyl acetate, wherein typical but non-limiting combinations include: a combination of toluene and methanol, a combination of ethyl acetate, butyl acetate, and isopropyl acetate, a combination of butyl acetate, isopropyl acetate, and n-propyl acetate, etc.

[0063] Preferably, the undesirable solvent includes any one or a combination of at least two of water, petroleum ether, methylcyclohexane, n-heptane, or n-hexane, wherein typical but non-limiting combinations include: a combination of water and petroleum ether, a combination of petroleum ether, n-heptane, and n-hexane, a combination of methylcyclohexane, water, petroleum ether, n-heptane, and n-hexane, etc.

[0064] As a preferred technical solution, the preparation method includes the following steps:

[0065] (1) Mix dimethylphenylphosphonate and 2,4,6-trimethylbenzoyl chloride and react at 40-60℃ for 1-3 h;

[0066] (2) The material obtained in step (1) is subjected to melt crystallization; the melt crystallization specifically includes the following process:

[0067] 1) Melting: Heat the material obtained in step (1) to 60-65℃ and hold for 30-60 minutes;

[0068] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0069] During crystallization, the reaction solution is placed in a crystallization tank, the temperature of the outer jacket is controlled to 40-60℃, the temperature of the inner jacket is adjusted to 10-45℃ over 30-120 minutes, and maintained for 30-240 minutes.

[0070] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 10-45℃ for 30-240 minutes, the pressure is reduced to 0.01-0.1MPa, and maintained for 30-240 minutes;

[0071] 4) Collect the crystals on the surface of the inner jacket and melt them at 60-65℃;

[0072] (3) Dissolve the material obtained in step (2) in a good solvent, then precipitate it in a bad solvent, and dry it after completing the solvation treatment. The good solvent is 25%-45% of the mass of the material after melting and crystallization, and the mass ratio of the good solvent to the bad solvent is controlled to be 1:(1-10) to obtain the photoinitiator.

[0073] Thirdly, the present invention provides a photocurable composition comprising a resin, a monomer, and the photoinitiator described in the first aspect.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] (1) The photoinitiator described in this invention has the characteristics of light color, low yellowness value, low odor, good fluidity and high storage stability. It also has good solubility in monomers, fast curing rate of the photocurable system, high adhesion to different plastic substrates, and excellent comprehensive performance.

[0076] The photoinitiator described in this invention can act as a dispersant, reducing the amount of dispersant used in the photocurable composition without affecting the relevant properties.

[0077] (2) The photoinitiator of this invention is white in appearance, with a yellowness value between 1.62 and 1.80, an odor grade of B, a flowability between 38.3° and 44.8°, a storage stability grade between 9 and 10, and a curing energy between 66.9 and 77.8 mJ·cm. 2The solubility of the monomer is between 50% and 65%, and the adhesion to different plastic substrates is between level 1 and level 2. Attached Figure Description

[0078] Figure 1 This is an enlarged morphological view of the photoinitiator described in Example 1;

[0079] Figure 2 This is a morphology diagram of the photoinitiator described in Example 1;

[0080] Figure 3 This is an enlarged morphological view of the photoinitiator described in Example 7;

[0081] Figure 4 This is a morphology diagram of the photoinitiator described in Example 7;

[0082] Figure 5 This is an enlarged morphological view of the photoinitiator described in Example 8;

[0083] Figure 6 This is the standard judgment chart for adhesion testing;

[0084] Figure 7 This is a schematic diagram of the crystallization apparatus described in this invention;

[0085] Among them, 1-inner jacket; 2-crystallization tank; 3-outer jacket; 4-liquid outlet. Detailed Implementation

[0086] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0087] Example 1

[0088] This embodiment provides a white solid photoinitiator, which is methyl 2,4,6-trimethylbenzoylphenylphosphonate; the melting point of the photoinitiator is 55℃-57℃.

[0089] The photoinitiator has a cross-shaped morphology, and its magnified morphology image and morphology image are shown below. Figure 1 and Figure 2 As shown.

[0090] The particle size distribution of the photoinitiator is: D50 is 61 μm, and D99 is 124 μm.

[0091] The molar extinction coefficient of the photoinitiator is 2420 L·mol⁻¹. -1 ·cm -1 (270nm).

[0092] The photoinitiator is prepared by the following method, which includes the following steps:

[0093] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 50°C for 3h;

[0094] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0095] 1) Melting: Heat the material obtained in step (1) to 62°C and hold for 50 minutes;

[0096] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0097] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 40°C within 60 minutes and maintained for 120 minutes.

[0098] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 45℃ for 60 minutes, the pressure is reduced to 0.04MPa, and maintained for 60 minutes; then the sweat is discharged.

[0099] 4) Collect the crystals on the surface of the inner jacket, melt them at 60℃, and collect them;

[0100] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.3, and the mass ratio of ethyl acetate to petroleum ether is 1:3 to obtain the photoinitiator.

[0101] Example 2

[0102] This embodiment provides a white solid photoinitiator, which is methyl 2,4,6-trimethylbenzoylphenylphosphonate; the melting point of the photoinitiator is 53-56℃.

[0103] The morphology of the photoinitiator includes a cross-shaped pattern.

[0104] The particle size distribution of the photoinitiator is: D50 is 42 μm, and D99 is 104 μm.

[0105] The molar extinction coefficient of the photoinitiator is 2423 L·mol⁻¹. -1 ·cm -1 (270nm).

[0106] The photoinitiator is prepared by the following method, which includes the following steps:

[0107] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 50°C for 4h;

[0108] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0109] 1) Melting: Heat the material obtained in step (1) to 60°C and hold for 60 minutes;

[0110] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0111] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 35°C within 120 minutes and maintained for 180 minutes.

[0112] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 37°C for 60 minutes, the pressure is reduced to 0.06 MPa, and maintained for 180 minutes; then the sweat is discharged.

[0113] 4) Collect the crystals on the surface of the inner jacket, melt them at 65°C, and collect them;

[0114] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.25, and the mass ratio of ethyl acetate to petroleum ether is 1:2 to obtain the photoinitiator.

[0115] Example 3

[0116] This embodiment provides a white solid photoinitiator, which is methyl 2,4,6-trimethylbenzoylphenylphosphonate; the melting point of the photoinitiator is 56-57℃.

[0117] The morphology of the photoinitiator includes a cross-shaped pattern.

[0118] The particle size distribution of the photoinitiator is: D50 is 79 μm, and D99 is 148 μm.

[0119] The molar extinction coefficient of the photoinitiator is 2419 L·mol⁻¹. -1 ·cm -1 (270nm).

[0120] The photoinitiator is prepared by the following method, which includes the following steps:

[0121] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 60°C for 2h;

[0122] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0123] 1) Melting: Heat the material obtained in step (1) to 65°C and hold for 30 minutes;

[0124] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0125] During crystallization, the reaction solution is placed in a crystallization tank, and the temperature of the outer jacket is controlled to 60°C within 45 minutes. The temperature of the inner jacket is then adjusted to 45°C within 45 minutes and maintained for 90 minutes.

[0126] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 50℃ for 60 minutes, the pressure is reduced to 0.02MPa, and maintained for 120 minutes; then the sweat is discharged.

[0127] 4) Collect the crystals on the surface of the inner jacket, melt them at 62℃, and collect them;

[0128] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.45, and the mass ratio of ethyl acetate to petroleum ether is 1:5 to obtain the photoinitiator.

[0129] Example 4

[0130] This embodiment provides a white solid photoinitiator, which differs from Example 1 in that the particle size distribution is different: D50 is 35 μm and D99 is 92 μm; all other aspects are the same as in Example 1.

[0131] The photoinitiator is prepared by the following method, which includes the following steps:

[0132] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 50°C for 3h;

[0133] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0134] 1) Melting: Heat the material obtained in step (1) to 62°C and hold for 50 minutes;

[0135] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0136] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 38°C within 60 minutes and maintained for 120 minutes.

[0137] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 40℃ for 60 minutes, the pressure is reduced to 0.04MPa, and maintained for 60 minutes; then the sweat is discharged.

[0138] 4) Collect the crystals on the surface of the inner jacket, melt them at 60℃, and collect them;

[0139] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.2, and the mass ratio of ethyl acetate to petroleum ether is 1:3, to obtain the photoinitiator.

[0140] Example 5

[0141] This embodiment provides a white solid photoinitiator, which differs from Example 1 in that it has a different particle size distribution: D50 is 83 μm and D99 is 149 μm; all other aspects are the same as in Example 1.

[0142] The photoinitiator is prepared by the following method, which includes the following steps:

[0143] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 50°C for 3h;

[0144] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0145] 1) Melting: Heat the material obtained in step (1) to 62°C and hold for 50 minutes;

[0146] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0147] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 41°C within 60 minutes and maintained for 120 minutes.

[0148] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 44℃ for 60 minutes, the pressure is reduced to 0.04MPa, and maintained for 60 minutes; then the sweat is discharged.

[0149] 4) Collect the crystals on the surface of the inner jacket, melt them at 60℃, and collect them;

[0150] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.5, and the mass ratio of ethyl acetate to petroleum ether is 1:3 to obtain the photoinitiator.

[0151] Example 6

[0152] This embodiment provides a white solid photoinitiator, which differs from Example 1 in that the particle size distribution is different: D50 is 85 μm and D99 is 154 μm; all other aspects are the same as in Example 1.

[0153] The photoinitiator is prepared by the following method, which includes the following steps:

[0154] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 50°C for 3h;

[0155] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0156] 1) Melting: Heat the material obtained in step (1) to 62°C and hold for 50 minutes;

[0157] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0158] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 42°C within 60 minutes and maintained for 120 minutes.

[0159] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 45℃ for 60 minutes, the pressure is reduced to 0.04MPa, and maintained for 60 minutes; then the sweat is discharged.

[0160] 4) Collect the crystals on the surface of the inner jacket, melt them at 60℃, and collect them;

[0161] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.55, and the mass ratio of ethyl acetate to petroleum ether is 1:3 to obtain the photoinitiator.

[0162] Example 7

[0163] This embodiment provides a white solid photoinitiator, which differs from Example 1 in that it has a spherical morphology. Its magnified morphology image and morphology diagram are shown below. Figure 3 and Figure 4 As shown; the particle size distribution of the photoinitiator is: D50 is 63 μm, D99 is 124 μm, and the molar extinction coefficient of the photoinitiator is 2429 L·mol⁻¹. -1 ·cm -1 (270nm), the rest are the same as in Example 1.

[0164] The photoinitiator is prepared by the following method, which includes the following steps:

[0165] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 50°C for 3h;

[0166] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0167] 1) Melting: Heat the material obtained in step (1) to 62°C and hold for 50 minutes;

[0168] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0169] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 20°C within 60 minutes and maintained for 200 minutes.

[0170] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 24℃ for 60 minutes, the pressure is reduced to 0.04MPa, and maintained for 60 minutes; then the sweat is discharged.

[0171] 4) Collect the crystals on the surface of the inner jacket, melt them at 60℃, and collect them;

[0172] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.34, and the mass ratio of ethyl acetate to petroleum ether is 1:9 to obtain the photoinitiator.

[0173] Example 8

[0174] This embodiment provides a white solid photoinitiator, which differs from Example 1 in that it has a flake-like morphology, as shown in the enlarged image below. Figure 5 As shown; the particle size distribution of the photoinitiator is: D50 is 60 μm, D99 is 122 μm, and the molar extinction coefficient of the photoinitiator is 2417 L·mol⁻¹. -1 ·cm -1 (270nm), the rest are the same as in Example 1.

[0175] The photoinitiator is prepared by the following method, which includes the following steps:

[0176] (1) Mix 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride and react at 55°C for 3h;

[0177] (2) The material obtained in step (1) is melt-crystallized. The specific process of melt-crystallization is as follows:

[0178] 1) Melting: Heat the material obtained in step (1) to 62°C and hold for 50 minutes;

[0179] 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank.

[0180] During crystallization, the reaction solution is placed in a crystallization tank. The temperature of the outer jacket is controlled to 45°C within 60 minutes, and the temperature of the inner jacket is adjusted to 28°C within 60 minutes and maintained for 240 minutes.

[0181] 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 31℃ for 60 minutes, the pressure is reduced to 0.04MPa, and maintained for 60 minutes; then the sweat is discharged.

[0182] 4) Collect the crystals on the surface of the inner jacket, melt them at 60℃, and collect them;

[0183] (3) Dissolve the material obtained in step (2) in ethyl acetate, then add petroleum ether to precipitate it, and dry it after completing the solvation treatment. The mass ratio of the material obtained in step (2) to ethyl acetate is controlled to be 1:0.28, and the mass ratio of ethyl acetate to petroleum ether is 1:7 to obtain the photoinitiator.

[0184] Example 9

[0185] This embodiment provides a photoinitiator, which differs from Example 1 in that it has an oily morphology, but is otherwise the same as Example 1.

[0186] The photoinitiator is prepared by the following method, which includes the following steps:

[0187] 170g of dimethylphenylphosphonate and 182g of 2,4,6-trimethylbenzoyl chloride were mixed and reacted at 50°C for 3 hours. The resulting material was dissolved in ethyl acetate, and then petroleum ether was added to precipitate it. After solvation treatment, the mixture was dried. The mass ratio of the resulting material to ethyl acetate was controlled to be 1:0.3, and the mass ratio of ethyl acetate to petroleum ether was 1:3. The resulting solid was heated to melt into a liquid and then left to stand for 48 hours. It remained a liquid to obtain the photoinitiator.

[0188] Comparative Example 1

[0189] This comparative example provides a photoinitiator: ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0190] Comparative Example 2

[0191] This comparative example provides a photoinitiator, which is methyl 2,4,6-trimethylbenzoylphenylphosphonate with a melting point of 50-52°C and is a yellow solid (Reference: Example 4 of US 4298738A).

[0192] Comparative Example 3

[0193] This comparative example provides a photoinitiator TPO: diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxychloride.

[0194] Performance testing

[0195] The photoinitiators described in Examples 1-9 and Comparative Examples 1-3 were tested as follows:

[0196] (1) Appearance: Observe its color by visual inspection; test its morphology by electron microscope with a magnification of 200-400, the magnification of the morphology magnification image is 380-400, and the magnification of the schematic diagram of the morphology image is 200-220.

[0197] (2) Resistance to yellowing:

[0198] ① Weigh out the photoinitiator, resin, and monomer according to the proportions in Table 1, and mix them evenly with ultrasonic stirring. The photoinitiator accounts for 5% of the total mass of the mixed coating, which is 100%. Apply the mixed coating to a glass slide with a coating tool with a thickness of 10μm, and irradiate it once under a mercury lamp to cure it into a film.

[0199] ②Then, use a 20μm wire bar coater to coat the photocurable system onto white test card paper, expose it under a mercury lamp light source to completely cure the sample, and finally use a color density meter to test the surface yellowness value b.

[0200] Table 1

[0201] Components Volume percentage Epoxy acrylate resin E51 30％ 1,6-Hexanediol diacrylate (HDDA) 10％ Trimethylolpropane triacrylate (TMPTA) 13％ Dispersant 3800 (dispersant, selected from Huihong Additives) 2％ Titanium dioxide 40％ Photoinitiators (Examples 1-9 and Comparative Examples 1-3) 5％

[0202] (3) Odor: Ten odor judges evaluated the odor of the fully cured sample according to five levels: A-no odor, B-slight odor, C-odor, D-pungent, and E-very pungent; the final average value is the test result.

[0203] (4) Solubility: The photoinitiator was dissolved in trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA) or 1,6-hexanediol diacrylate (HDDA) to prepare a sample with a concentration increment of 5%. After ultrasonic dissolution, the sample was allowed to stand at 40°C in the dark for 72 hours. The solubility of the initiator was determined by the absence of obvious precipitation.

[0204] (5) Curing energy: Weigh the photoinitiator, resin and monomer according to the proportion in Table 1 to prepare a photoinitiation system. Stir it with ultrasonic to make it evenly mixed. Apply the mixed coating to white test card paper with a wire bar applicator with a thickness of 10μm. Place it under a mercury lamp light source to irradiate once to cure it into a film. Press a 1kg weight onto the A4 paper and pull it repeatedly three times on the cured film. The standard for complete curing is that no scratches are produced. Record the energy required for curing with a UV energy meter.

[0205] (6) Adhesion: Prepare the UV-curable system according to the ratio in Table 1, and then use a 10μm wire bar coater to apply the UV-curable system to plastic substrates of different materials (polystyrene PS, polyvinyl chloride PVC, polyethylene terephthalate PET, polycarbonate PC). Expose the samples under a mercury lamp light source to allow them to fully cure. Then, use the cross-cut adhesion test to test the adhesion. Use a utility knife to draw 6 parallel cutting lines perpendicular to the material surface with uniform force. Then, draw 6 parallel lines perpendicular to the cutting lines at 90° to form a grid pattern. Then, stick tape to the center of the grid and pull it off quickly and continuously 10 times at an angle of about 60°. Observe the phenomenon of paint film peeling and calculate the corresponding state of the grid in the cross-cut adhesion test. Figure 6 The standard is used to make the judgment.

[0206] (7) Flowability-Angle of repose test: 50g of powder flows out naturally from the funnel opening at a height of 10cm. After the flow stops, measure the angle between the inclined plane that forms the powder cone on the plane and the horizontal plane, which is the angle of repose °.

[0207] (8) Storage stability: After 10 boxes were stacked and stored for one month using 10 kg cardboard boxes, the number of boxes in which the powder was still relatively loose and did not clump together was counted.

[0208] (9) Substitution of dispersant: 5% of the photoinitiator in Examples 1, 7, 8, 9 and Comparative Examples 1-2 were added to 1,6-hexanediol diacrylate, 2% dispersant was added to each system 1, and 1.5% dispersant was added to each system 2. After the systems were mixed evenly, they were coated onto glass slides with a wire bar coater with a thickness of 10 μm and placed under a mercury lamp light source for irradiation. The decay of double bond groups with light irradiation time during photopolymerization was monitored in real time by infrared online monitoring. The infrared absorption intensity of key groups at each irradiation time was tracked to obtain the final double bond conversion rate.

[0209] The test results are summarized in Tables 2-4 and Figures 1-5 middle.

[0210] Table 2

[0211]

[0212] Table 3

[0213]

[0214]

[0215] Table 4

[0216]

[0217] Analysis of the data in Tables 2 and 3 shows that the photoinitiator described in this invention is white in appearance, with a yellowness value between 1.62 and 1.80, an odor grade of B, a flowability between 38.3° and 44.8°, a storage stability grade between 9 and 10, and a curing energy between 66.9 and 77.8 mJ·cm⁻¹. 2 The solubility of the monomer is between 50% and 65%, and the adhesion to different plastic substrates is between level 1 and level 2. The photoinitiator of the present invention has the characteristics of light color, low yellowness value, low odor, good fluidity and high storage stability. In addition, it has good solubility in the monomer, the photocurable system formed has a fast curing rate, high adhesion to different plastic substrates, and excellent comprehensive performance.

[0218] Analysis of the data in Table 4 shows that, based on the double bond conversion rate as an example, the present invention demonstrates that the photoinitiator described in this invention can act as a dispersant. In the photocurable composition, the amount of dispersant can be reduced without affecting the relevant properties.

[0219] Analysis of Comparative Example 1 and Example 1 shows that the performance of Comparative Example 1 is not as good as that of Example 1, proving that the photoinitiator of the structure described in this invention has better performance.

[0220] Analysis of Comparative Example 2 and Example 1 shows that the performance of Comparative Example 2 is not as good as that of Example 1, proving that the photoinitiator of the structure described in this invention has better performance when the melting point is controlled at 53-57℃.

[0221] Analysis of Comparative Example 3 and Example 1 shows that the performance of Comparative Example 3 is not as good as that of Example 1 or is basically the same as that of Example 1, proving that the photoinitiator described in this invention also has advantages over industrially mature photoinitiators.

[0222] Analysis of Examples 4-6 and Example 1 shows that the performance of Examples 4-6 is not as good as that of Example 1, proving that the photoinitiator described in this invention has better performance when the particle size distribution is controlled within the preferred range.

[0223] Analysis of Examples 7-9 and Example 1 shows that the performance of Example 9 is not as good as that of Examples 1 and Examples 7-8, proving that the photoinitiator described in this invention has better performance in controlling morphology within the preferred range.

[0224] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A photoinitiator, characterized in that, The photoinitiator is methyl 2,4,6-trimethylbenzoylphenylphosphonate: The photoinitiator has a melting point of 53-57℃; The preparation method of the photoinitiator includes the following steps: (1) Mix dimethylphenylphosphonate and 2,4,6-trimethylbenzoyl chloride and react at 40-60℃ for 1-3 h; (2) The material obtained in step (1) is subjected to melt crystallization; the melt crystallization specifically includes the following process: 1) Melting: Heat the material obtained in step (1) to 60-65℃ and hold for 30-60 min; 2) Crystallization: The material obtained in step 1) is placed in a crystallization device, which includes a crystallization tank, an outer jacket disposed on the outer surface of the crystallization tank, and an inner jacket disposed inside the crystallization tank; During crystallization, the reaction solution is placed in a crystallization tank, the temperature of the outer jacket is controlled to 40-60℃, the temperature of the inner jacket is adjusted to 10-45℃ for 30-120 min, and maintained for 30-240 min. 3) Sweating: After the crystallization reaction solution is discharged, the temperature of the inner jacket is adjusted to 10-50℃ for 30-240 min, the pressure is reduced to 0.01-0.1 MPa, and maintained for 30-240 min; 4) Collect the crystals on the surface of the inner jacket and melt them at 60-65℃; (3) Dissolve the material obtained in step (2) in a good solvent, then precipitate it in a bad solvent, and dry it after completing the solvation treatment. The good solvent is 25%-45% of the mass of the material after melting and crystallization, and the mass ratio of the good solvent to the bad solvent is controlled to be 1:(1-10) to obtain the photoinitiator. The good solvent is ethyl acetate and the bad solvent is petroleum ether.

2. A photocurable composition, characterized in that, The photocurable composition comprises a resin, a monomer, and the photoinitiator of claim 1.

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