Photoinitiator, preparation method therefor and use thereof

Abstract

The present invention relates to a photoinitiator, a preparation method therefor and a use thereof. The photoinitiator comprises methyl (2,4,6-trimethylbenzoyl) phenyl phosphonate, and the melting point of the photoinitiator is 53-57°C. The photoinitiator described in the present invention has the characteristics of a pale-colored appearance, low yellowness value, low odor, good fluidity and high storage stability, has good solubility in monomers, and can act as a dispersing agent. The formed photocuring system has a fast curing rate, a high adhesive force on the surfaces of different plastic substrates, and excellent overall performance.

Description

A photoinitiator and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of photoinitiators, and in particular to a photoinitiator, a preparation method thereof and an application thereof. Background Art

[0002] Photoinitiator, also known as photosensitizer or photocuring agent, is a type of compound that can absorb energy of a certain wavelength in the ultraviolet light region (250-420nm) or visible light region (400-800nm), generate free radicals, cations, etc., thereby initiating monomer polymerization, cross-linking and curing.

[0003] Photoinitiators are divided into two categories based on 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 divided into cleavage photoinitiators and hydrogen abstraction photoinitiators based on their mechanism of generating free radicals. An ideal photoinitiator should have the following advantages: (1) low cost and simple synthesis; (2) the photoinitiator and its photocleavage products should be non-toxic and odorless; (3) good stability and convenient for long-term storage; (4) the absorption spectrum of the photoinitiator must match the emission band of the radiation source and have a high molar extinction coefficient; and (5) high initiation efficiency.

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

[0005] Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention aims to provide a photoinitiator, a preparation method thereof, and an application thereof. The photoinitiator has the characteristics of light appearance color, low yellowness value, low odor, good fluidity, and high storage stability. In addition, the photoinitiator has good solubility in monomers and can also act as a dispersant. The resulting photocuring system has a fast curing rate, high adhesion to the surfaces of different plastic substrates, and excellent overall performance.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a photoinitiator, wherein the photoinitiator comprises methyl 2,4,6-trimethylbenzoylphenylphosphonate;

[0009] The melting point of the photoinitiator is 53-57°C, for example, 53.5°C, 54°C, 54.5°C, 55°C, 55.5°C, 56°C, 56.5°C, etc.

[0010] In the present invention, the photoinitiator has the characteristics of light appearance color, low yellowness value, low odor, good fluidity and high stability, good solubility in monomers, the formed photocuring system has a fast curing rate, high adhesion on the surfaces of different plastic substrates, and excellent comprehensive performance.

[0011] In addition, the photoinitiator described in the present invention not only has excellent photoinitiating performance itself, but also acts as a dispersant. In the photocurable composition, the photoinitiator described in the present invention can reduce the amount of dispersant used, save costs, and reduce the adverse effects of excessive additives on the system.

[0012] Preferably, the morphology of the photoinitiator includes any one of a cross-shaped, spherical, quasi-spherical or flake-shaped, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of a cross-shaped and a spherical shape, a combination of a spherical, quasi-spherical and flake-shaped shape, a combination of a cross-shaped, a spherical, quasi-spherical and flake-shaped shape, etc., and a cross-shaped shape is further preferred.

[0013] Preferably, the crossing shape includes a penetrating crossing shape or a non-penetrating crossing shape.

[0014] Preferably, the cross shape is formed by at least two regular and / or irregular columnar intersections.

[0015] In the present invention, typical but non-limiting examples of the columnar shape include a cuboid, a cube, a prism, a cylinder, a quasi-cylinder, and the like.

[0016] In the present invention, the morphology of the photoinitiator is preferably the above-mentioned morphology. The photoinitiator with the above-mentioned morphology has good stability, better compatibility with other components in the photocurable composition, can better play the role of a dispersant, and the resulting photocurable composition has a fast curing rate, high adhesion to the surfaces of different plastic substrates, and excellent overall performance.

[0017] Preferably, the particle size distribution of the photoinitiator is: D50 is 40-80 μm (for example, 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.).

[0018] In the present invention, D50 refers to the particle size at the point where the volume is 50% 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 the laser diffraction scattering method; the same applies to D99.

[0019] In the present invention, the particle size distribution of the photoinitiator is controlled within a preferred range because: the interaction force between the photoinitiator particles within this range reaches a good balance, so that the performance of the photoinitiator itself is in an optimal state. When used in a photocurable composition, it can better play the role of a dispersant, has a strong ability to cooperate with other components, and has excellent comprehensive performance; if the particle size is too small, it is easy to produce dust and static electricity, has high requirements for equipment, is inconvenient to use, and the specific surface area of ​​the particle size product becomes larger, the storage stability is reduced, the storage period is shortened, and the effective utilization rate of the raw materials is reduced; if the particle size is too large, the fluidity is poor, the solubility in the monomer is poor, and it is difficult to play the role of a dispersant well, resulting in a slow curing rate of the formed photocurable system and poor adhesion to the surfaces of different plastic substrates.

[0020] In the present invention, the morphology and particle size distribution of the photoinitiator cooperate with each other, so that the comprehensive performance of the photoinitiator is further improved.

[0021] Preferably, the D99 of the photoinitiator is ≤150 μm, for example, 145 μm, 140 μm, 135 μm, 130 μm, 120 μm, 115 μm, etc.

[0022] Preferably, the molar extinction coefficient of the photoinitiator is 200-2500 L·mol -1 cm -1 , for example 400 L·mol -1 cm -1 、600L·mol -1 cm -1 、800L·mol -1 cm -1 、1000L·mol -1 cm -1 、1200L·mol -1 cm -1 、1400L·mol -1 cm -1 、1600L·mol -1 cm -1 、2000L·mol -1 cm -1 、2200L·mol -1 cm -1 、2400L·mol -1 cm -1 wait.

[0023] In the present invention, the molar extinction coefficient test method is as follows: dissolve the photoinitiator in a solvent (including but not limited to methylcyclohexane) to prepare a solution with a concentration of 1 mol / L, place the solution in a cuvette, use an ultraviolet spectrophotometer to test the ultraviolet absorbance of the solution between 200nm and 500nm (for example, 250nm, 270nm, 290nm, 370nm, etc.), and calculate the molar extinction coefficient at different wavelengths using Formula 1: A = ε·l·c Formula 1

[0024] Where A is the absorbance; ε is the molar extinction coefficient, unit is L·mol -1 cm -1 ; l is the optical path length, which is 1 cm here; c is the concentration, which is 1 mol / L here.

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

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

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

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

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

[0030] Dimethylphenylphosphonate and 2,4,6-trimethylbenzoyl chloride are mixed, reacted and melt-crystallized to obtain the photoinitiator.

[0031] Preferably, the reaction temperature is 40-60°C, for example, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, etc.

[0032] Preferably, the reaction time is 1-3 h, for example, 1.2 h, 1.4 h, 0.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h, etc.

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

[0034] Preferably, the melting includes operations of heating and keeping the temperature.

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

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

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

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

[0039] In the present 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 the 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 perform 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., more preferably 35-45°C.

[0043] In the present invention, controlling the temperature of the inner jacket during the first adjustment to be within a preferred range is beneficial to forming a photoinitiator having a particle size within a preferred range and a cross-shaped morphology.

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

[0045] Preferably, after the inner jacket is adjusted to the temperature for the first time, it is maintained for 30-240 minutes, for example, 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 includes discharging the reaction liquid after crystallization, adjusting the temperature of the inner jacket for a second time and reducing the pressure.

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

[0048] In the present invention, the temperature of the inner jacket is controlled to be within a preferred range during the second adjustment, which is conducive to forming a photoinitiator with a particle size within a preferred range and a cross-shaped morphology.

[0049] Preferably, the time for adjusting the inner jacket to the temperature for the second time is 30-240 min, for example, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, etc.

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

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

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

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

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

[0057] In the present invention, the good solvent refers to a solvent that has good solubility for the material after melt crystallization. The judgment standard in the present invention is that the material and the good solvent are mixed in a mass ratio of 1:2 at 30°C, and can be completely dissolved within half an hour; the poor solvent refers to a solvent that has poor solubility for the material after melt crystallization. The judgment standard in the present invention is that the material and the good solvent are mixed in a mass ratio of 1:10 at 30°C, and cannot be completely dissolved within half an hour.

[0058] Preferably, based on the mass of the melt-crystallized material being 100%, the mass of the good solvent is 25%-45%, for example, 25%, 30%, 35%, 40%, 45%, etc.

[0059] In the present invention, taking the mass of the melt-crystallized material as 100%, controlling the mass of the good solvent within a preferred range 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), wherein 1-10 can be 2, 4, 6, 8, etc., and more preferably 1:(1-5).

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

[0062] Preferably, the good solvent includes any one of toluene, methanol, ethyl acetate, butyl acetate, isopropyl acetate or n-propyl acetate, or a combination of at least two thereof, 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 poor solvent includes any one of water, petroleum ether, methylcyclohexane, n-heptane or n-hexane, or a combination of at least two of them, 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 comprises the following steps:

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

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

[0067] 1) Melting: heating the material obtained in step (1) to 60-65°C and keeping the temperature for 30-60 minutes;

[0068] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution is placed in a crystallization tank, the temperature of the outer jacket is controlled to 40-60°C, the temperature of the inner jacket is adjusted to 10-45°C over 30-120 minutes, and maintained for 30-240 minutes;

[0070] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 10-45°C over 30-240 minutes, reduce the pressure to 0.01-0.1 MPa, and maintain for 30-240 minutes;

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

[0072] (3) dissolving the material obtained in step (2) in a good solvent, then precipitating it in a poor solvent, and drying it after completing the solvation treatment, wherein the mass of the material after the melt crystallization is 100%, the mass of the good solvent is 25%-45%, and the mass ratio of the good solvent to the poor solvent is controlled to be 1:(1-10), thereby obtaining the photoinitiator.

[0073] In a third aspect, 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 of the present invention has the characteristics of light appearance color, low yellowness value, low odor, good fluidity and high storage stability, and has good solubility in monomers. The resulting photocurable system has a fast curing rate, high adhesion to the surfaces of different plastic substrates, and excellent comprehensive performance.

[0076] The photoinitiator of the present invention can play the role of a dispersant, and in the photocurable composition, the amount of the dispersant can be reduced without affecting the relevant properties.

[0077] (2) The photoinitiator of the present invention has a white appearance, a yellowness value between 1.62-1.80, an odor grade of B, a fluidity between 38.3°-44.8°, a storage stability grade between 9-10, and a curing energy between 66.9-77.8 mj·cm 2The solubility in the monomer is between 50% and 65%, and the adhesion on the surface of different plastic substrates is between level 1 and level 2. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] FIG1 is an enlarged view of the morphology of the photoinitiator described in Example 1;

[0079] FIG2 is a morphology diagram of the photoinitiator described in Example 1;

[0080] FIG3 is an enlarged view of the morphology of the photoinitiator described in Example 7;

[0081] FIG4 is a morphology diagram of the photoinitiator described in Example 7;

[0082] FIG5 is an enlarged view of the morphology of the photoinitiator described in Example 8;

[0083] Figure 6 is a standard judgment diagram for adhesion testing;

[0084] FIG7 is a schematic structural diagram of the crystallization device according to the present invention;

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

[0086] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0087] Example 1

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

[0089] The morphology of the photoinitiator is cross-shaped, and its magnified morphology and morphology diagram are shown in Figures 1 and 2 respectively.

[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 cm -1 (270nm).

[0092] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0095] 1) Melting: The material obtained in step (1) was heated to 62°C and kept warm for 50 minutes;

[0096] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45°C within 60 minutes, and the temperature of the inner jacket was adjusted to 40°C within 60 minutes and maintained for 120 minutes;

[0098] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 45° C. over 60 minutes, reduce the pressure to 0.04 MPa, and maintain for 60 minutes; and sweat;

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

[0100] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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, wherein the photoinitiator is methyl 2,4,6-trimethylbenzoylphenylphosphonate; and the melting point of the photoinitiator is 53-56°C.

[0103] The morphology of the photoinitiator includes a cross shape.

[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 cm -1 (270nm).

[0106] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0109] 1) Melting: The material obtained in step (1) was heated to 60°C and kept warm for 60 minutes;

[0110] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45°C within 60 minutes, and the temperature of the inner jacket was adjusted to 35°C within 120 minutes and maintained for 180 minutes;

[0112] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 37° C. over 60 minutes, reduce the pressure to 0.06 MPa, and maintain for 180 minutes; and sweat;

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

[0114] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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, wherein the photoinitiator is methyl 2,4,6-trimethylbenzoylphenylphosphonate; and the melting point of the photoinitiator is 56-57°C.

[0117] The morphology of the photoinitiator includes a cross shape.

[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 cm -1 (270nm).

[0120] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0123] 1) Melting: The material obtained in step (1) was heated to 65°C and kept warm for 30 minutes;

[0124] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 60°C within 45 minutes, and the temperature of the inner jacket was adjusted to 45°C within 45 minutes and maintained for 90 minutes;

[0126] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 50° C. over 60 minutes, reduce the pressure to 0.02 MPa, and maintain for 120 minutes; then sweat;

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

[0128] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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, D99 is 92 μm; the rest is the same as Example 1.

[0131] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0134] 1) Melting: The material obtained in step (1) was heated to 62°C and kept warm for 50 minutes;

[0135] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45°C within 60 minutes, and the temperature of the inner jacket was adjusted to 38°C within 60 minutes and maintained for 120 minutes;

[0137] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 40° C. over 60 minutes, reduce the pressure to 0.04 MPa, and maintain for 60 minutes; then sweat;

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

[0139] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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 controlled to be 1:3, to obtain the photoinitiator.

[0140] Example 5

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

[0142] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0145] 1) Melting: The material obtained in step (1) was heated to 62°C and kept warm for 50 minutes;

[0146] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45°C within 60 minutes, and the temperature of the inner jacket was adjusted to 41°C within 60 minutes and maintained for 120 minutes;

[0148] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 44° C. over 60 minutes, reduce the pressure to 0.04 MPa, and maintain for 60 minutes; then sweat;

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

[0150] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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 controlled to be 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, D99 is 154 μm; the rest is the same as Example 1; the rest is the same as Example 1.

[0153] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0156] 1) Melting: The material obtained in step (1) was heated to 62°C and kept warm for 50 minutes;

[0157] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45°C within 60 minutes, and the temperature of the inner jacket was adjusted to 42°C within 60 minutes and maintained for 120 minutes;

[0159] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 45° C. over 60 minutes, reduce the pressure to 0.04 MPa, and maintain for 60 minutes; and sweat;

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

[0161] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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 its morphology is spherical, and its morphology enlarged view and morphology are shown in Figures 3 and 4 respectively; 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 cm -1 (270nm), and the rest are the same as in Example 1.

[0164] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0167] 1) Melting: The material obtained in step (1) was heated to 62°C and kept warm for 50 minutes;

[0168] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45° C. within 60 minutes, and the temperature of the inner jacket was adjusted to 20° C. within 60 minutes and maintained for 200 minutes;

[0170] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 24° C. over 60 minutes, reduce the pressure to 0.04 MPa, and maintain for 60 minutes; and sweat;

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

[0172] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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 controlled to be 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, and an enlarged view of its morphology is shown in FIG5 . 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 cm -1 (270nm), and the rest are the same as in Example 1.

[0175] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

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

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

[0178] 1) Melting: The material obtained in step (1) was heated to 62°C and kept warm for 50 minutes;

[0179] 2) Crystallization: placing the material obtained in step 1) in a crystallization device, wherein the crystallization device comprises 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 the crystallization, the reaction solution was placed in a crystallization tank, and the temperature of the outer jacket was controlled to 45° C. within 60 minutes, and the temperature of the inner jacket was adjusted to 28° C. within 60 minutes and maintained for 240 minutes;

[0181] 3) Sweating: drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 31° C. over 60 minutes, reduce the pressure to 0.04 MPa, and maintain for 60 minutes; then sweat;

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

[0183] (3) dissolving the material obtained in step (2) in ethyl acetate, then adding petroleum ether for precipitation, completing the solvation treatment and drying, wherein 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 controlled to be 1:7, to obtain the photoinitiator.

[0184] Example 9

[0185] This embodiment provides a photoinitiator, which differs from Example 1 in that the morphology is oily, and the rest is the same as Example 1.

[0186] The preparation method of the photoinitiator is obtained by the following preparation method, which comprises the following steps:

[0187] 170 g of dimethylphenylphosphonate and 182 g of 2,4,6-trimethylbenzoyl chloride were mixed and reacted at 50° C. for 3 h. The obtained material was dissolved in ethyl acetate, and then petroleum ether was added for precipitation. After completing the solvation treatment, the mixture was dried. The mass ratio of the obtained material to ethyl acetate was controlled to be 1:0.3, and the mass ratio of ethyl acetate to petroleum ether was controlled to be 1:3. The obtained solid was heated and melted into a liquid, and then allowed to stand for 48 h while remaining liquid, thereby obtaining 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, which has 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 oxide.

[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 enlarged image is 380-400, and the magnification of the schematic diagram of the morphology image is 200-220.

[0197] (2) Yellowing resistance:

[0198] ① Weigh the photoinitiator, resin, and monomer according to the proportions in Table 1 and mix them evenly using ultrasonic stirring. The mass of the photoinitiator accounts for 5% based on the total mass of the mixed coating as 100%. Apply the mixed coating on a glass slide with a film applicator with a thickness of 10 μm and place it under a mercury lamp for one-time curing to form a film.

[0199] ②Then use a 20μm wire rod applicator to apply the light-curing system on 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 measure the surface yellowness value b.

[0200] Table 1

[0201] (3) Odor: Ten odor judges evaluated the odor of the fully cured samples according to five levels: A - no odor, B - slight odor, C - odor, D - pungent, and E - very pungent; the final average value was the test result.

[0202] (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 in the dark at 40°C for 72 hours. The solubility of the initiator was obtained based on the absence of obvious precipitation.

[0203] (5) Curing energy: The photoinitiator, resin, and monomer were weighed according to the proportions in Table 1 to form a photoinitiator system. The mixture was uniformly mixed using ultrasonic stirring. The mixed coating was applied to a white test cardboard using a wire rod coater with a thickness of 10 μm. The mixed coating was placed under a mercury lamp and irradiated once to form a film. A 1 kg weight was pressed against an A4 paper and repeatedly pulled three times on the cured film. The complete cure was defined as the absence of scratches. The energy required for curing was recorded using a UV energy meter.

[0204] (6) Adhesion: Prepare a photocuring system according to the ratio in Table 1, and then use a 10μm wire rod applicator to apply the photocuring system on plastic substrates of different materials (polystyrene PS, polyvinyl chloride PVC, polyethylene terephthalate PET, polycarbonate PC), and expose the sample under a mercury lamp light source to completely cure it; then use the grid method to test the adhesion. Use a wallpaper knife to apply uniform force perpendicular to the surface of the material and smoothly draw 6 parallel cutting lines. Then, draw 6 parallel lines perpendicular to the cutting lines at 90° to form a grid pattern. Then use tape to stick to the center of the formed grid and pull it off continuously and quickly 10 times at an angle of about 60°. Observe the phenomenon of paint film falling off, and make a judgment by calculating the state of the grid in the grid corresponding to the standard in Figure 6.

[0205] (7) Flowability-angle of repose test: 50 g of powder is allowed to flow naturally from the mouth of a funnel at a height of 10 cm. After the flow stops, the angle between the inclined surface forming the powder cone on the plane and the horizontal plane is measured, which is the angle of repose °.

[0206] (8) Storage stability: Packed in 10 kg cartons, 10 cartons are stacked and placed for one month. After opening, count the number of cartons in which the powder is still relatively loose and not agglomerated.

[0207] (9) Substitutability for dispersants: 5% of the photoinitiators in Examples 1, 7, 8, 9 and Comparative Examples 1-2 were added to 1,6-hexanediol diacrylate, 2% of the dispersant was added to System 1, and 1.5% of the dispersant was added to System 2. The systems were mixed evenly and then coated on a glass slide using a wire rod coater with a thickness of 10 μm. The slides were then irradiated under a mercury lamp light source. The decay of the double bond groups during the photopolymerization process with the irradiation time was monitored online by real-time infrared. The infrared absorption intensity of the key groups at each irradiation time was tracked to obtain the final double bond conversion rate.

[0208] The test results are summarized in Tables 2-4 and Figures 1-5.

[0209] Table 2

[0210] Table 3

[0211] Table 4

[0212] According to the data in Table 2 and Table 3, the photoinitiator of the present invention has a white appearance, a yellowness value between 1.62-1.80, an odor grade of B, a fluidity between 38.3°-44.8°, a storage stability grade between 9-10, and a curing energy between 66.9-77.8 mj·cm 2 The solubility in the monomer is between 50% and 65%, and the adhesion on the surface of different plastic substrates is between level 1 and level 2. The photoinitiator of the present invention has the characteristics of light appearance color, low yellowness value, low odor, good fluidity and high storage stability, and has good solubility in the monomer. The photocuring system formed has a fast curing rate, high adhesion on the surface of different plastic substrates, and excellent comprehensive performance.

[0213] Analysis of the data in Table 4 shows that the present invention uses double bond conversion as an example for experimental verification, demonstrating that the photoinitiator of the present invention can function as a dispersant. In the photocurable composition, the amount of dispersant can be reduced without affecting the relevant properties.

[0214] 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, which proves that the photoinitiator with the structure described in the present invention has better performance.

[0215] 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, which proves that the photoinitiator with the structure of the present invention has better performance by controlling the melting point at 53-57°C.

[0216] 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, which proves that the photoinitiator described in the present invention also has advantages over industrially mature photoinitiators.

[0217] 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, which proves that the photoinitiator of the present invention has better performance when controlling the particle size distribution within the preferred range.

[0218] Analysis of Examples 7-9 and Example 1 shows that the performance of Example 9 is not as good as that of Example 1 and Examples 7-8, which proves that the photoinitiator of the present invention has better performance in controlling morphology within the preferred range.

[0219] The applicant states that the present invention is intended to illustrate the detailed methods of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A photoinitiator, characterized in that, The photoinitiator includes methyl 2,4,6-trimethylbenzoyl phenylphosphonate: The melting point of the photoinitiator is 53 - 57 °C.

2. The photoinitiator according to claim 1, wherein, The morphology of the photoinitiator includes any one or a combination of at least two of cross-shaped, spherical, quasi-spherical or flaky; Preferably, the cross-shaped includes penetrating cross or non-penetrating cross; Preferably, the cross-shaped is formed by the intersection of at least two regular and / or irregular columns.

3. The photoinitiator according to claim 1 or 2, characterized in that, The particle size distribution of the photoinitiator is: D50 is 40 - 80 μm.

4. The photoinitiator according to any one of claims 1 to 3, characterized in that, The D99 of the photoinitiator ≤ 150 μm.

5. The photoinitiator according to any one of claims 1-4, characterized in that, The molar extinction coefficient of the photoinitiator is 200 - 2500 L·mol -1 ·cm -1 .

6. A method for preparing a photoinitiator according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: Mix dimethyl phenylphosphonate and 2,4,6-trimethylbenzoyl chloride, react and perform melt crystallization to obtain the photoinitiator.

7. The preparation method according to claim 6, characterized in that, The temperature of the reaction is 40 - 60 °C; Preferably, the reaction time is 1 - 3 h.

8. The preparation method according to claim 6 or 7, characterized in that, The melt crystallization process includes melting, crystallization, sweating and remelting; Preferably, the melting includes heating and heat preservation operations; Preferably, the temperature is raised to 60 - 65 °C; Preferably, the heat preservation time is 30 - 60 min; Preferably, the crystallization is carried out in a crystallization device, and the crystallization device includes a crystallization tank, an outer jacket arranged on the outer surface of the crystallization tank and an inner jacket arranged inside the crystallization tank; Preferably, during crystallization, the reaction liquid is placed in the crystallization tank, the temperature of the outer jacket is controlled, and the temperature of the inner jacket is adjusted for the first time to perform crystallization; Preferably, the temperature of the outer jacket is controlled to 40 - 60 °C; Preferably, the temperature of the inner jacket is adjusted for the first time to 10 - 45 °C; Preferably, the time taken to adjust the inner jacket to the temperature for the first time is 30 - 120 min; Preferably, after adjusting the inner jacket to the temperature for the first time, it is maintained for 30 - 240 min; Preferably, the sweating includes discharging the reaction liquid after crystallization, adjusting the temperature of the inner jacket for the second time and reducing the pressure; Preferably, the temperature of the inner jacket is adjusted for the second time to 10 - 50 °C; Preferably, the time taken to adjust the inner jacket to the temperature for the second time is 30 - 240 min; Preferably, after adjusting the inner jacket to the temperature for the second time, it is maintained for 30 - 240 min; Preferably, the pressure is reduced to 0.01 - 0.1 MPa; Preferably, after reducing the pressure to 0.01 - 0.1 MPa, it is maintained for 30 - 240 min; Preferably, after sweating, the crystals on the surface of the inner jacket are collected and melted; Preferably, the melting temperature is 60 - 65 °C; Preferably, after melt crystallization, it also includes solvation treatment and drying; Preferably, the solvation treatment includes dissolving the material in a good solvent and then precipitating it in a poor solvent; Preferably, based on the mass of the material after melt crystallization being 100%, the mass of the good solvent is 25% - 45%; Preferably, the mass ratio of the good solvent to the poor solvent is 1:(1 - 10); 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; Preferably, the poor solvent includes any one or a combination of at least two of water, petroleum ether, methylcyclohexane, n-heptane or n-hexane.

9. The preparation method according to any one of claims 6-8, characterized in that, The preparation method includes the following steps: (1) Mix dimethylphenylphosphonate and 2,4,6-trimethylbenzoyl chloride, and react at 40-60 °C for 1-3 h; (2) Perform melt crystallization on the material obtained in step (1); the melt crystallization specifically includes the following process: 1) Melting: Heat the material obtained in step (1) to 60-65 °C and keep it warm for 30-60 min; 2) Crystallization: Place the material obtained in step 1) in a crystallization device, which includes a crystallization tank, an outer jacket arranged on the outer surface of the crystallization tank, and an inner jacket arranged inside the crystallization tank; During crystallization, the reaction solution is placed in the crystallization tank, the temperature of the outer jacket is controlled to 40-60 °C, and the temperature of the inner jacket is adjusted to 10-45 °C in 30-120 min and kept for 30-240 min; 3) Sweating: Drain the reaction solution after crystallization, adjust the temperature of the inner jacket to 10-50 °C in 30-240 min, reduce the pressure to 0.01-0.1 MPa, and keep it for 30-240 min; 4) Collect the crystals on the surface of the inner jacket and melt them at 60-65 °C; (3) Dissolve the material obtained in step (2) in a good solvent, then precipitate it in a poor solvent, dry it after solventization treatment, wherein, based on the mass of the material after melt crystallization being 100%, the mass of the good solvent is 25%-45%, and the mass ratio of the good solvent to the poor solvent is controlled to be 1:(1-10) to obtain the photoinitiator.

10. A photocurable composition, characterized in that, The photocurable composition includes a resin, a monomer and the photoinitiator according to any one of claims 1-5.

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