A photoinitiator, preparation method, application and ink composition

Abstract

The present invention discloses a photoinitiator, an ink composition and the application of the photoinitiator. The photoinitiator is 3-methyl-4'-phenyldibenzophenone, and the 3-methyl-4'-phenyldibenzophenone has a specific particle distribution. The ink composition prepared from the photoinitiator particles has high abrasion resistance and alcohol resistance.

Description

Technical Field

[0001] The present invention belongs to the field of polymer composites, and particularly relates to a photoinitiator, a preparation method, an application, and an ink composition. Background Art

[0002] With the development of the economy, people have higher and higher expectations for a better life, and printing is required for both identification and decoration needs on plastic products. Plastic printing refers to printing on plastic rolls such as films, sheets, artificial leather, and wallpapers, and flexographic printing and gravure printing are commonly used. Its basic principle is the same as that of paper printing.

[0003] However, the inks used in plastic printing are different from those used in paper printing. The inks for plastic printing are mainly suitable for use on rotary gravure printing machines. The compatibility of the inks for plastic printing with the printing machine, the curing performance of the inks, and the adhesion performance of the inks on the plastic surface all affect the product quality of printed plastics. In particular, poor abrasion resistance and poor alcohol resistance limit the application of the inks for plastic printing.

[0004] Due to different plastic resins and modifiers, as well as different plastic forming processes, different plastic products have different relative effects on printing inks. The commonly used PET resin in the market is widely used in daily plastic products due to its good plasticity, but its surface performance is poor. For products obtained by printing or copying through a printing machine with inks, the surface performance and adhesion performance are both poor. In particular, its abrasion resistance and alcohol resistance are poor, and the inks are easily scratched and peeled off.

[0005] Among the types of inks, photo-curable inks are an important branch. The abrasion and alcohol resistance of photo-curable inks and their adhesion on plastic materials are important factors affecting plastic printing products.

[0006] Therefore, it is an urgent technical problem for those skilled in the art to prepare a photo-curable ink suitable for printing with good abrasion and alcohol resistance and plastic adhesion. Summary of the Invention

[0007] The purpose of the present invention is to provide a photoinitiator for preparing inks, which can significantly improve the abrasion and alcohol resistance of the inks and their adhesion on plastic materials.

[0008] Necessarily, the present invention also provides a preparation method of the above photoinitiator.

[0009] Necessarily, the present invention also provides an application of the above photoinitiator.

[0010] More necessarily, the present invention also provides an ink composition prepared by applying the above photoinitiator.

[0011] The present invention provides a photoinitiator.

[0012] The photoinitiator is 3-methyl-4'-phenyldibenzoyl methane, having the following structural formula:

[0013]

[0014] The particle distribution of the 3-methyl-4'-phenyldibenzoyl methane satisfies that

[0015]

[0016] the range of a is 1.2 - 2.0, preferably 1.3 - 1.5.

[0017] The meanings of D10, D50, D75, and D90 in the particle size distribution of the photoinitiator are all well-known in the art. Among them, the particle size distribution D50, also known as the average particle size or median particle size, indicates that the photoinitiator particles with a particle size below this value account for 50% of the total volume; the particle size distribution D10 indicates that the photoinitiator particles with a particle size below this value account for 10% of the total volume; the particle size distribution D75 indicates that the photoinitiator particles with a particle size below this value account for 75% of the total volume; the particle size distribution D90 indicates that the photoinitiator particles with a particle size below this value account for 90% of the total volume.

[0018] The numerator part of the formula calculates the difference between D90 and D50. This difference reflects the distribution range of larger particle size particles. The larger this difference, the wider the range of large particles in the particle size distribution; the denominator part of the formula calculates the difference between D75 and D10. This part reflects the distribution of smaller particle size particles. The larger this difference, the greater the particle size variation among small particles. By calculating the ratio of these two parts, the parameter a is used to measure the distribution difference in different particle size intervals. Specifically, the magnitude of the a value reflects the distribution width difference between large particles and small particles. The parameter a is used to measure the uniformity and concentration of the particle distribution. If the a value is larger, it means that the particle size distribution is wider and the particle size difference is larger; conversely, a smaller a value means that the particle size distribution is more concentrated and the size difference is smaller. The optimal range of the a value is 1.3 to 1.5, which means that within this range, the particle distribution is neither too concentrated nor too dispersed, and the best physical properties can be achieved. The parameter a can be used to well quantify the particle distribution characteristics.

[0019] Among them, the particle distribution of the 3-methyl-4'-phenyldibenzoyl methane also satisfies that

[0020] the full width at half maximum FWHM is 130 - 310 μm, preferably 190 - 240 μm.

[0021] The full width at half maximum (FWHM) is the full width at half the maximum height of the interval particle size distribution curve of the photoinitiator, which is the difference between two particle size values corresponding to half of the maximum height of the interval particle size distribution curve of the photoinitiator. The interval particle size distribution of the photoinitiator has the well-known meaning in the art, which is defined as a curve plotted with particle size as the abscissa and volume percentage content as the ordinate, and can accurately reflect the particle size distribution characteristics of the photoinitiator particles. The above particle size parameters can all be measured by a laser particle size analyzer.

[0022] The parameters a and FWHM balance the range of the particle size distribution. The larger the FWHM, the wider and more dispersed the particle size distribution, and the greater the variation in particle size; a smaller FWHM indicates a more concentrated particle size distribution and more consistent particle sizes. The value of the parameter a is related to this. When a is larger, it also reflects a larger difference in particle size distribution. The parameter a quantifies the uniformity of particles by comparing the distribution differences in different particle size intervals, and its calculation takes into account the width between different particle size distribution percentile points (such as D10, D50, D75, D90). FWHM is a direct measurement of the width of the overall distribution curve at the middle part (half height). The two together reflect the width and concentration degree of the particle size distribution. When the FWHM is small, it indicates that the particle size distribution of the particles is more concentrated. At this time, the value of a also tends to be small because the difference between large particles and small particles is small. If the particle size distribution curve shows a large skew or bimodal shape, then the value of a may be large because the particle size differences in different intervals are large in this form, while the FWHM may not significantly reflect this asymmetry. On the contrary, if the distribution is more symmetric and concentrated, FWHM and a may more consistently reflect the particle distribution. In practical applications, FWHM is usually used to directly measure and characterize the width of the particle size distribution, while a can provide a more detailed analysis, especially when it is necessary to distinguish the distribution differences between large particles and small particles. The combination of the two can more comprehensively reflect the physical distribution of particles and help evaluate and optimize the quality of particles.

[0023] The present invention also provides a preparation method of the photoinitiator, comprising the following steps:

[0024] Add ethanol to 3-methyl-4'-phenylbenzophenone powder. The added mass of ethanol is 4-6 times that of 3-methyl-4'-phenylbenzophenone powder. After dissolution, stir at a constant temperature of 65 °C for 30-40 min, and the stirring speed is 40-60 r / min. Drop 0.5 mol / L hydrochloric acid at the 15-20th minute, and the added content of hydrochloric acid is 2-4 wt% of 3-methyl-4'-phenylbenzophenone. Cool to 12 °C under the condition of a stirring speed of 10-20 r / min, and the cooling rate is 3-5 °C / 5 min. After crystallization, filter and dry to obtain 3-methyl-4'-phenylbenzophenone particles.

[0025] The present invention also provides an ink composition, which comprises the following components by weight:

[0026] 2 - 6 parts of the photoinitiator as described above;

[0027] 53 - 61 parts of resin;

[0028] 36 - 40 parts of acrylate monomers;

[0029] 0.1 - 0.3 part of additives.

[0030] Wherein, the resin is selected from one or a mixture of modified rosin resin, allyl ester prepolymer (molecular weight 30,000 - 60,000), polyketone resin, modified epoxy acrylate, polyester acrylate, alkyd resin, styrene acrylate.

[0031] Wherein, the acrylate monomers are selected from one or more of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, bis - trimethylolpropane tetraacrylate, dipropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate.

[0032] Wherein, the additives are amine co - initiators.

[0033] Wherein, the ink composition further comprises 0.2 - 0.3 part of dispersant, 0.2 - 0.3 part of leveling agent and 0.2 - 0.3 part of antioxidant.

[0034] The photoinitiator of the present invention is used to improve the wear resistance and alcohol resistance of the ink.

[0035] Compared with the prior art, the photoinitiator of the present invention has a reasonable particle size distribution. The arithmetic square root of the square number between D90 (μm) and D50 (μm), and the arithmetic square root of the square number between D7 (μm) and D10 (μm), the ratio of the two arithmetic square roots is within a reasonable range, indicating that the photoinitiator has appropriate particle size and particle size uniformity.

[0036] The photoinitiator molecules have certain light absorption ability in the ultraviolet region (250 - 400 nm) or visible light region (400 - 800 nm). After directly or indirectly absorbing light energy, the initiator molecules transition from the ground state to the excited singlet state, and then undergo intersystem crossing to the excited triplet state; after undergoing unimolecular or bimolecular chemical reactions in the excited singlet state or triplet state, active fragments capable of initiating monomer polymerization are generated. These active fragments can be free radicals, cations, anions, etc. According to different initiation mechanisms, photoinitiators can be divided into free - radical polymerization photoinitiators and cationic photoinitiators, among which free - radical polymerization photoinitiators are the most widely used.

[0037] The inventors of this patent have found that during the preparation of photocurable inks, the particle size distribution of photoinitiators has an important impact on the final properties of the inks. The main components of photocurable inks include monomers, initiators, and additives. Under environmental protection requirements, photocurable inks do not contain volatile organic compounds (VOCs), so they lack traditional organic solvents. In this case, the dissolution behavior of photoinitiators in inks is significantly different from that of inorganic salts in water. When an inorganic salt such as table salt dissolves in water, it completely dissociates into ions to form a homogeneous solution; while the dissolution process of photoinitiators is more complex. In the ink system, due to the lack of a benign organic solvent, the dissolution behavior of photoinitiators is actually a process similar to "swelling", that is, the initiator molecules partially enter the molecular gaps of monomers or oligomers, but they still maintain some characteristics of the solid aggregated state. This "mixed state" makes the distribution of photoinitiators in monomers different from that of inorganic salts in water, but exists in the form of swollen particles.

[0038] The particle size of photoinitiators has a significant impact on their dissolution behavior and polymerization reaction in monomers. Since photoinitiators exist in a swollen form, their particle size and distribution will affect the diffusion and action range of the initiators in monomers:

[0039] (1) Light absorption ability and photoinitiation efficiency: The particle size of photoinitiators directly affects their light absorption ability in monomers. If the particles are too small, although the specific surface area is large and the light absorption ability is strong, due to the too fast light absorption rate of the swollen particles, it may cause the local monomer polymerization to be too rapid, forming an uneven polymerization network. On the contrary, if the particles are too large, the light absorption ability and speed are insufficient, which may lead to incomplete reactions. Therefore, an appropriate distribution of particle sizes (for example, the preferred a value range of 1.3 - 1.5 in the examples) can ensure that the photoinitiator generates free radicals after absorbing light energy, making the polymerization reaction of monomers more uniform.

[0040] (2) Influence on swelling behavior and aggregated state: The particle size of photoinitiators affects their swelling degree in monomers and their ability to maintain the aggregated state. Larger particles, due to limited swelling, can maintain more solid aggregated structures. This aggregated state can provide stable active sites in the photoinitiation reaction, thus better controlling the generation rate and concentration distribution of free radicals or cations, which is crucial for ensuring the overall uniform curing and excellent physical properties of the ink.

[0041] When the particles maintain an appropriate size and distribution, they can form a uniform network structure in the ink, improving the comprehensive performance of the ink. If the particles are too small, the cured layer of the ink may become brittle; if they are too large, it may lead to uneven curing or delamination. In addition, due to the special "swelling" phenomenon of the photoinitiator in the monomer, re-precipitation may occur after the photoinitiator is dissolved. The size and distribution of these re-precipitated particles are directly affected by the initial particle characteristics. Reasonably controlling the particle size distribution of the initiator can effectively avoid performance non-uniformity caused by re-precipitation and ensure the overall quality of the ink.

[0042] The present invention can obtain photoinitiator particles with a specific particle size distribution through various methods such as screening by a grading sieve. For example, the recrystallization method can be used. Dissolve 3-methyl-4'-phenylbenzophenone powder in ethanol, and after dissolution, stir at a constant temperature of 65 °C for 30 - 40 min, with a stirring speed of 40 - 60 r / min. At the 15th - 20th minute, add 0.5 mol / L hydrochloric acid, and the added content of hydrochloric acid is 2 - 4 wt% of 3-methyl-4'-phenylbenzophenone. Cool to 12 °C under the condition of a stirring speed of 10 - 20 r / min, with a cooling rate of 3 - 5 °C / 5 min. After crystallization, filter and dry to obtain 3-methyl-4'-phenylbenzophenone particles with a specific distribution trend that can achieve the purpose of the present invention.

[0043] After the 3-methyl-4'-phenylbenzophenone of the present invention is dissolved, the particle size of the 3-methyl-4'-phenylbenzophenone particles is controlled by adjusting the stirring speed, the content and addition timing of hydrochloric acid, the cooling rate, etc. The polar effect of hydrochloric acid molecules affects the crystallization rate of 3-methyl-4'-phenylbenzophenone in ethanol, thereby affecting the particle size of 3-methyl-4'-phenylbenzophenone.

[0044] The surface tension of the plastic film material is low, and the ink-fixing performance of the film material is poor. When the ink is printed on the plastic film material, it is easy to deink, and the adhesion of the ink is poor. Moreover, the plastic film material is easy to bend, which is also likely to cause deinking or scratching off the ink; the film material is not resistant to the solvents or acid-base auxiliaries of the ink, and is prone to ink spreading or ink melting. The particle distribution of the photoinitiator in the ink affects the light absorption ability and light absorption speed, thereby affecting the degree of polymerization reaction crosslinking of the ink resin and acrylate monomers, and thus can affect the surface properties of the ink on the plastic film material, such as wear resistance, alcohol resistance, etc.

[0045] However, it is found in the present invention that when the photoinitiator meets a certain distribution trend, it can play an optimal initiation effect on the polymerization of the ink, and the prepared ink has high wear resistance and alcohol resistance. Description of the Drawings

[0046] Figure 1 It is the particle size distribution diagram of the 3-methyl-4'-phenylbenzophenone particles prepared in Example 3. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0048] The raw materials used in the embodiments and comparative examples are described as follows:

[0049] 3-Methyl-4'-phenylbenzophenone: Aladdin reagent;

[0050] Leveling agent: BYK, Germany, model: UV3500 (BYK);

[0051] Antioxidant: BHT, commercially available;

[0052] Dispersant: Lubrizol Solsperse 24000 super dispersant from the United States;

[0053] Resin: polyester acrylate, Changxing, Taiwan, China, 6353;

[0054] Acrylate monomers: ethoxylated trimethylolpropane triacrylate, Aladdin reagent;

[0055] The remaining raw materials were commercially available.

[0056] Example 1

[0057] Ethanol was added to 3-methyl-4'-phenylbenzophenone powder, the added mass of ethanol was 5 times that of 3-methyl-4'-phenylbenzophenone powder, after dissolution, constant temperature stirring was performed at 65°C for 30 minutes, the stirring speed was 40r / min, 0.5mol / L hydrochloric acid was dropped at the 15th minute, the added content of hydrochloric acid was 2wt% of 3-methyl-4'-phenylbenzophenone, the mixture was cooled to 12°C under the condition of stirring speed of 20r / min, the cooling speed was 5°C / 5min, and after crystallization, filtration and drying were performed to obtain 3-methyl-4'-phenylbenzophenone particles.

[0058] Example 2

[0059] Ethanol was added to 3-methyl-4'-phenylbenzophenone powder, the added mass of ethanol was 4 times that of 3-methyl-4'-phenylbenzophenone powder, after dissolution, constant temperature stirring was performed at 65°C for 40 minutes, the stirring speed was 60r / min, 0.5mol / L hydrochloric acid was dropped at the 17th minute, the added content of hydrochloric acid was 3wt% of 3-methyl-4'-phenylbenzophenone, the mixture was cooled to 12°C under the condition of stirring speed of 15r / min, the cooling speed was 5°C / 5min, and after crystallization, filtration and drying were performed to obtain 3-methyl-4'-phenylbenzophenone particles.

[0060] Example 3

[0061] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 6 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 35 min, and the stirring speed was 50 r / min. At the 18th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 4 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 15 r / min, and the cooling rate was 3 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0062] Example 4

[0063] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 5.5 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 35 min, and the stirring speed was 55 r / min. At the 18th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 2.5 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 15 r / min, and the cooling rate was 4 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0064] Example 5

[0065] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 4.5 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 35 min, and the stirring speed was 45 r / min. At the 16th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 3.5 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 13 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0066] Example 6

[0067] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 5 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 35 min, and the stirring speed was 48 r / min. At the 15th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 2 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 16 r / min, and the cooling rate was 4 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0068] Example 7

[0069] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 5.5 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 40 min, and the stirring speed was 55 r / min. At the 20th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 3 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 18 r / min, and the cooling rate was 3 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0070] Example 8

[0071] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 4.5 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 40 min, and the stirring speed was 45 r / min. At the 15th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 3.5 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 11 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0072] Example 9

[0073] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added. The added mass of ethanol was 5 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 40 min, and the stirring speed was 55 r / min. At the 15th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 3 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 15 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0074] Example 10

[0075] In 3-methyl-4'-phenylbenzophenone powder, ethanol was added. The added mass of ethanol was 5.5 times that of 3-methyl-4'-phenylbenzophenone powder. After dissolution, it was stirred at a constant temperature of 65 °C for 38 min, and the stirring speed was 52 r / min. At the 18th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 2.5 wt% of 3-methyl-4'-phenylbenzophenone. It was cooled to 12 °C at a stirring speed of 18 r / min, and the cooling rate was 4 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenylbenzophenone particles.

[0076] Example 11

[0077] In 3-methyl-4'-phenylbenzophenone powder, ethanol was added. The added mass of ethanol was 4.5 times that of 3-methyl-4'-phenylbenzophenone powder. After dissolution, it was stirred at a constant temperature of 65 °C for 38 min, and the stirring speed was 48 r / min. At the 15th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 3.5 wt% of 3-methyl-4'-phenylbenzophenone. It was cooled to 12 °C at a stirring speed of 13 r / min, and the cooling rate was 4 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenylbenzophenone particles.

[0078] Example 12

[0079] In 3-methyl-4'-phenylbenzophenone powder, ethanol was added. The added mass of ethanol was 5 times that of 3-methyl-4'-phenylbenzophenone powder. After dissolution, it was stirred at a constant temperature of 65 °C for 38 min, and the stirring speed was 52 r / min. At the 16th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 3 wt% of 3-methyl-4'-phenylbenzophenone. It was cooled to 12 °C at a stirring speed of 15 r / min, and the cooling rate was 4 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenylbenzophenone particles.

[0080] Example 13

[0081] In 3-methyl-4'-phenylbenzophenone powder, ethanol was added. The added mass of ethanol was 4.5 times that of 3-methyl-4'-phenylbenzophenone powder. After dissolution, it was stirred at a constant temperature of 65 °C for 30 min, and the stirring speed was 44 r / min. At the 17th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 2 wt% of 3-methyl-4'-phenylbenzophenone. It was cooled to 12 °C at a stirring speed of 17 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenylbenzophenone particles.

[0082] Example 14

[0083] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added, and the added mass of ethanol was 4 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 40 min, and the stirring speed was 40 r / min. At the 20th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 2 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 15 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0084] Example 15

[0085] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added, and the added mass of ethanol was 6 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 30 min, and the stirring speed was 60 r / min. At the 20th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 4 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 20 r / min, and the cooling rate was 3 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0086] Comparative Example 1

[0087] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added, and the added mass of ethanol was 4 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 40 min, and the stirring speed was 60 r / min. Then it was cooled to 12 °C under the condition of a stirring speed of 15 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0088] Comparative Example 2

[0089] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added, and the added mass of ethanol was 4 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 40 min, and the stirring speed was 60 r / min. At the 20th minute, 0.5 mol / L sodium hydroxide was dropped in, and the added content of sodium hydroxide was 3 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 15 r / min, and the cooling rate was 5 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0090] Comparative Example 3

[0091] In 3-methyl-4'-phenyldibenzoyl methane powder, ethanol was added, and the added mass of ethanol was 4 times that of 3-methyl-4'-phenyldibenzoyl methane powder. After dissolution, it was stirred at a constant temperature of 65 °C for 45 min, and the stirring speed was 30 r / min. At the 10th minute, 0.5 mol / L hydrochloric acid was dropped in, and the added content of hydrochloric acid was 6 wt% of 3-methyl-4'-phenyldibenzoyl methane. It was cooled to 12 °C under the condition of a stirring speed of 5 r / min, and the cooling rate was 6 °C / 5 min. After crystallization, it was filtered and dried to obtain 3-methyl-4'-phenyldibenzoyl methane particles.

[0092] The particle sizes of the products prepared in Examples 1-15 and Comparative Examples 1-3 were statistically analyzed.

[0093] The measuring instrument was an Omec particle size analyzer. All the prepared samples were added to the sample cell of the injector. After waiting for the light shielding ratio to be stable, the samples were immediately measured to obtain the data, as shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] The 3-methyl-4'-phenyldibenzoyl methane particles prepared in Examples 1-15 and Comparative Examples 1-3 were respectively made into inks according to the following methods (as shown in the ink formulation table in Table 2 below):

[0098] The 3-methyl-4'-phenyldibenzoyl methane particles, resin (polyester acrylate), acrylate monomer (ethoxylated trimethylolpropane triacrylate), amine co-initiator (6422TF, Changxing Special Materials (Zhuhai) Co., Ltd.), dispersant (Lubrizol Solsperse 24000 super dispersant, USA), leveling agent (UV3500 (BYK)), and antioxidant (antioxidant BHT) were mixed evenly according to the parts by weight shown in Table 2 to obtain the ink.

[0099] Among them, the photoinitiators in Experimental Examples 1-15 were the 3-methyl-4'-phenyldibenzoyl methane particles prepared in Examples 1 to 15, and the photoinitiators in Experimental Examples 16 and 17 were both the 3-methyl-4'-phenyldibenzoyl methane particles prepared in Example 3.

[0100] The photoinitiators in Comparative Experimental Example 1, Comparative Experimental Example 2, and Comparative Experimental Example 3 were respectively the 3-methyl-4'-phenyldibenzoyl methane particles prepared in Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0101] Table 2 Ink component ratio table (unit: parts by weight)

[0102]

[0103] Testing Methods for Ink Properties

[0104] 1. Glossiness Test (QB573 - 83)

[0105] The determination of the glossiness of the ink is carried out in accordance with the "QB573 - 83 Inspection Method for Ink Glossiness". The ink is placed on a PET plastic film and scraped into a thin layer printing sample of the same size. It is measured using a DTH - 80 type gloss meter. Under the irradiation of a fixed light source, the ratio of the reflected light flux of the sample to that of the standard surface is used to express the glossiness of the sample ink (with the reflected light flux of the standard surface being 100%). The higher the glossiness, the better its gloss performance.

[0106] 2. Abrasion Resistance (Adhesion)

[0107] The abrasion resistance test is determined with reference to the "GB 1768 - 1979 Test Method for Coating Abrasion Resistance". The specific steps are as follows: The ink is evenly rolled on PET plastic films of the same size and left to dry for later use. The sample plate is fixed on the working turntable of the abrasion resistance tester using an MCJ - 01A type friction testing machine (provided by Jinan LanGuang Electromechanical Technology Co., Ltd.), and the parameters are set to 200 times and 40N. After the test, the sample is taken out, and the floating debris is brushed off with a brush and weighed. The difference in weight before and after is the weight loss of the ink. The smaller the weight loss of the ink, the better the abrasion resistance.

[0108] 3. Alcohol Resistance Treatment

[0109] The sample is immersed in 75% alcohol (25°C) for 12 hours, taken out, rinsed, dried, and then its glossiness and abrasion resistance (adhesion) are tested according to the above - mentioned test methods.

[0110] Glossiness Reduction Rate = |(Glossiness before Alcohol Resistance Treatment - Glossiness after Alcohol Resistance Treatment)| / Glossiness before Alcohol Resistance Treatment; Adhesion Reduction Rate = |(Adhesion before Alcohol Resistance Treatment - Adhesion after Alcohol Resistance Treatment)| / Adhesion before Alcohol Resistance Treatment.

[0111] Table 3 Test Results

[0112]

[0113]

[0114] The above data show that for the photoinitiator prepared by the present invention, by using a photoinitiator with a specific particle distribution as the photoinitiator for the ink, the ink prepared has a high glossiness, and in particular, the abrasion resistance and alcohol resistance of the ink on the surface of the plastic film are both good.

[0115] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photoinitiator, characterized in that: The photoinitiator is 3-methyl-4'-phenylbenzophenone, having the following structural formula: The particle distribution of the 3-methyl-4'-phenylbenzophenone satisfies: The range of a is 1.2-2.

0.

2. The photoinitiator according to claim 1, characterized in that: The range of a is 1.3-1.

5.

3. The photoinitiator according to claim 1, characterized in that: The particle distribution of the 3-methyl-4'-phenylbenzophenone also satisfies: The half-width (FWHM) is 130-310 μm.

4. The photoinitiator according to claim 3, characterized in that: The particle distribution of the 3-methyl-4'-phenylbenzophenone also satisfies: The half-width (FWHM) is 190-240 μm.

5. The method for preparing the photoinitiator according to any one of claims 1 to 3, characterized in that: The following steps are involved: Ethanol is added to 3-methyl-4'-phenylbenzophenone powder, wherein the added mass of ethanol is 4-6 times that of the 3-methyl-4'-phenylbenzophenone powder. After dissolution, the mixture is stirred at a constant temperature of 65° C. for 30-40 minutes at a stirring speed of 40-60 r / min. At the 15th to 20th minute, 0.5 mol / L hydrochloric acid is added dropwise, wherein the added content of the hydrochloric acid is 2-4 wt % of the 3-methyl-4'-phenylbenzophenone solution. The mixture is cooled to 12° C. at a stirring speed of 10-20 r / min at a cooling speed of 3-5° C. / 5 min. After crystallization, the mixture is filtered and dried to obtain 3-methyl-4'-phenylbenzophenone particles satisfying the particle size distribution.

6. An ink composition, characterized in that: The components include the following by weight: 2-6 parts of the photoinitiator according to any one of claims 1-3; Resin 15-50 parts; 15-30 parts of acrylic acid ester monomer; Additives 0.1-3 parts.

7. The ink composition according to claim 6, wherein: The resin is selected from one or more mixtures of modified rosin resin, allyl ester prepolymer, polyketone resin, modified epoxy acrylate, polyester acrylate, alkyd resin, and styrene acrylate.

8. The ink composition according to claim 6, wherein: The acrylate monomer is selected from one or more of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ditrimethylolpropane acrylate, tripropylene glycol diacrylate, and propoxylated neopentyl glycol diacrylate.

9. The ink composition according to claim 6, wherein: The auxiliary agent is an amine auxiliary initiator.

10. The ink composition according to claim 6, wherein: The ink composition further comprises 0.2-2 parts of a dispersant, 0.2-0.3 parts of a leveling agent and 0.2-0.3 parts of an antioxidant.

11. Use of the photoinitiator according to any one of claims 1 to 4 in preparing ink for printing on plastic products.

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