Photoinitiator, and preparation method therefor and use thereof, and ink composition

Abstract

Disclosed in the present invention are a photoinitiator, an ink composition, and a use of the photoinitiator. The photoinitiator is 3-methyl-4'-phenylbenzophenone, the 3-methyl-4'-phenylbenzophenone has a specific particle distribution, and the ink composition prepared from photoinitiator particles has relatively high wear resistance and alcohol resistance.

Description

A photoinitiator, a preparation method, an application and an ink composition TECHNICAL FIELD

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

[0002] With the development of economy, people have higher and higher expectations for a better life, and both the identification demand and the decoration demand on plastic products need to be printed. Plastic printing refers to printing on plastic rolls such as film, sheet, artificial leather and wallpaper, and common flexible printing and intaglio printing, which have the same basic principle as paper printing.

[0003] However, the ink used for plastic printing is different from the ink used for paper printing. The ink used for plastic printing is mainly suitable for use on a rotary intaglio printing machine. The adaptability of the ink used for plastic printing to the printing machine, the curing performance of the ink and the adhesion performance of the ink on the plastic surface all affect the product quality of the printed plastic, especially the poor wear resistance and poor alcohol resistance, which limit the application of the ink used for plastic printing.

[0004] Different plastic products have different relative effects on printing ink due to different plastic resins and modifiers and different plastic forming processes. The commonly used PET resin on the market is widely used in daily plastic products due to its good plasticity, but its surface performance is not good. The product obtained by printing or copying through the printing machine has poor surface performance and adhesion performance, especially poor wear resistance and alcohol resistance, and the ink is easily scratched and peeled off.

[0005] Among the types of ink, photocurable ink is an important branch. The wear resistance and alcohol resistance of photocurable ink and the adhesion on plastic material are important factors affecting plastic printing products.

[0006] Therefore, it is an urgent technical problem for those skilled in the art to prepare a photocurable ink suitable for printing with good wear resistance and alcohol resistance and good adhesion on plastic. SUMMARY

[0007] The purpose of the present application is to provide a photoinitiator for preparing ink, which can significantly improve the wear resistance and alcohol resistance of the ink and the adhesion on plastic material.

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

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

[0010] More desirably, the present application also provides an ink composition prepared by using the above-mentioned photoinitiator.

[0011] The present application provides a photoinitiator,

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

[0013] The particle distribution of the 3-methyl-4'-phenylbenzophenone satisfies,

[0014] The range of a is 1.2-2.0, preferably 1.3-1.5.

[0015] The particle size distribution D10, D50, D75, D90 of the photoinitiator are all meanings known in the art, wherein the particle size distribution D50, also known as the average particle size or median particle size, represents that the photoinitiator particles with particle size below this value account for 50% of the total volume; the particle size distribution D10 represents that the photoinitiator particles with particle size below this value account for 10% of the total volume; the particle size distribution D75 represents that the photoinitiator particles with particle size below this value account for 75% of the total volume; and the particle size distribution D90 represents that the photoinitiator particles with particle size below this value account for 90% of the total volume.

[0016] The numerator part of the formula The difference between D90 and D50 is calculated. This difference reflects the distribution range of larger particles. The larger this difference is, the wider the range of large particles in the particle size distribution is; the denominator part of the formula The difference between D75 and D10 is calculated. This part reflects the distribution of smaller particles. The larger this difference is, the greater the particle size variation among small particles is. By calculating the ratio of the two parts, the parameter a is used to measure the distribution difference in different particle size ranges. Specifically, the size of a value reflects the difference in the distribution width 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; on the contrary, the smaller a value means that the particle size distribution is more concentrated and the size difference is smaller. The best range of 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 distribution characteristics of the particles.

[0017] The particle distribution of the 3-methyl-4'-phenylbenzophenone also satisfies:

[0018] The full width at half maximum FWHM is 130-310 μm, preferably 190-240 μm.

[0019] The half-height width FWHM of the interval particle size distribution curve of the photoinitiator is the difference between the two particle sizes corresponding to half the maximum height of the interval particle size distribution curve of the photoinitiator. The interval particle size distribution of the photoinitiator is a meaning known in the art, defined as a curve plotted with particle size as the abscissa and volume percentage content as the ordinate, which can more accurately reflect the particle size distribution characteristics of the photoinitiator particles. The above particle size parameters can be determined by a laser particle size analyzer.

[0020] Both parameters a and FWHM measure the range of the particle size distribution. The larger the FWHM, the wider the particle size distribution, and the greater the variation in particle size; a smaller FWHM indicates a more concentrated particle size distribution, and the particle sizes are more uniform. The value of parameter a is related to this, and when a is larger, it also reflects a larger particle size distribution difference. Parameter a quantifies the uniformity of the particles by comparing the distribution differences between different particle size intervals, and its calculation takes into account the width between different particle size distribution percentiles (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). Both reflect the width and concentration of the particle size distribution. When FWHM is small, the particle size distribution is concentrated, and the value of a tends to be small because the difference between large and small particles is small. If the particle size distribution curve shows a large skew or bimodal shape, the value of a may be large because the particle size difference between different intervals is large, and FWHM may not reflect this asymmetry. Conversely, if the distribution is more symmetric and concentrated, FWHM and a may 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 more detailed analysis, especially when it is necessary to distinguish the distribution difference between large and small particles. The combination of the two can more comprehensively reflect the physical distribution of the particles and help evaluate and optimize the quality of the particles.

[0021] The present application also provides a preparation method of the photoinitiator, comprising the following steps:

[0022] In the 3-methyl-4'-phenyl benzophenone powder, add ethanol, the added mass of ethanol is 4-6 times of the mass of 3-methyl-4'-phenyl benzophenone powder, after dissolution, constant temperature stirring at 65℃ for 30-40min, the stirring speed is 40-60r / min, at the 15-20min, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 2-4wt% of 3-methyl-4'-phenyl benzophenone, under the condition of stirring speed of 10-20r / min, cooling to 12℃, cooling speed 3-5℃ / 5min, after crystallization, filter and dry, to obtain 3-methyl-4'-phenyl benzophenone particles.

[0023] The present application also provides an ink composition comprising the following ingredients by weight:

[0024] The photoinitiator as described above 2-6 parts;

[0025] Resin 53-61 parts;

[0026] Acrylate monomer 36-40 parts;

[0027] Auxiliary 0.1-0.3 parts.

[0028] The resin is selected from one or more mixtures of modified rosin resin, allyl ester prepolymer (molecular weight 30-60 thousand), polyketone resin, modified epoxy acrylate, polyester acrylate, alkyd resin, styrene acrylate.

[0029] The acrylate monomer is selected from one or more of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, bis-trimethylolpropane acrylate, tripropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate

[0030] The auxiliary is an amine co-initiator.

[0031] The ink composition further comprises 0.2-0.3 parts of a dispersing agent, 0.2-0.3 parts of a leveling agent and 0.2-0.3 parts of an antioxidant.

[0032] The photoinitiator of the present application is used to improve the wear resistance and alcohol resistance of the ink.

[0033] Compared with the prior art, the photoinitiator of the present application has a reasonable particle size distribution, the ratio of the arithmetic square root of the square of D90(μm) and D50(μm) to the arithmetic square root of the square of D7(μm) and D10(μm) is within a reasonable range, indicating that the photoinitiator has a suitable particle size and uniformity.

[0034] The photoinitiator molecule has a certain light absorption capacity in the ultraviolet region (250-400 nm) or the visible region (400-800 nm). After direct or indirect absorption of light energy, the initiator molecule transitions from the ground state to the excited singlet state, and then undergoes intersystem crossing to the excited triplet state. After experiencing monomolecular or bimolecular chemical action in the excited singlet state or triplet state, active fragments that can initiate monomer polymerization are generated, which can be free radicals, cations, anions, etc. According to the 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.

[0035] The inventors of the present patent have found that the particle size distribution of photoinitiator has a significant impact on the final performance of the ink during the preparation of the photocurable ink. The main components of the photocurable ink include monomers, initiators, and additives, and under the environmental requirements, the photocurable ink does not contain volatile organic compounds (VOC), thus lacks traditional organic solvents, in which case the solubility behavior of the photoinitiator in the ink is significantly different from the solubility behavior of inorganic salts in water. When inorganic salts such as table salt dissolve in water, they completely dissociate into ions to form a uniform solution; the solubilization process of the photoinitiator is more complex. In the ink system, due to the lack of benign organic solvents, the solubility behavior of the photoinitiator is actually a process similar to "swelling", i.e., the initiator molecules partially enter the intermolecular gaps of the monomers or oligomeric monomers, but still retain some solid aggregate characteristics. This "mixed state" makes the distribution of the photoinitiator in the monomer different from the distribution state of inorganic salts in water, but exists in the form of swollen particles.

[0036] The particle size of the photoinitiator has a significant impact on its solubility behavior in the monomer and the polymerization reaction. Since the photoinitiator exists in a swollen form, its particle size and distribution will affect the diffusion and action range of the initiator in the monomer:

[0037] (1) Light absorption capacity and photoinitiation efficiency: The particle size of the photoinitiator directly affects its light absorption capacity in the monomer. If the particle is too small, although the specific surface area is large and the light absorption capacity is strong, due to the too fast light absorption speed of the swollen particle, it may cause the local monomer to polymerize too quickly, forming an uneven polymerization network. On the contrary, if the particle is too large, the light absorption capacity and speed are insufficient, which may lead to incomplete reaction. Therefore, a proper distribution of the particle size (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 the monomer more uniform.

[0038] (2) Influence of swelling behavior and aggregate state: The particle size of the photoinitiator affects its swelling degree in the monomer and its ability to maintain an aggregate state. Larger particles have limited swelling degree and can maintain more solid aggregate structures, which can provide stable active sites in the photoinitiation reaction, thereby better controlling the generation rate and concentration distribution of free radicals or cations, which is crucial for ensuring the overall uniform curing of the ink and excellent physical properties.

[0039] When the particles maintain proper size and distribution, they can form a uniform network structure in the ink, improving the overall performance of the ink. If the particles are too small, the cured layer of the ink can become brittle, and if they are too large, it can lead to uneven curing or delamination. In addition, due to the special "swelling" phenomenon of the photoinitiator in the monomer, reprecipitation can occur after the photoinitiator is dissolved. The size and distribution of these reprecipitated particles are directly affected by the characteristics of the original particles. Proper control of the particle size distribution of the initiator can effectively prevent performance inconsistencies caused by reprecipitation, ensuring the overall quality of the ink.

[0040] The present application can obtain photoinitiator particles with a specific particle size distribution through various methods such as sieving. For example, the method of recrystallization can be used. Dissolve 3-methyl-4'-phenylbenzophenone powder in ethanol, stir at 65°C for 30-40 minutes after dissolution, stirring speed is 40-60r / min, add 0.5mol / L hydrochloric acid at 15-20 minutes, the addition amount of hydrochloric acid is 2-4wt% of 3-methyl-4'-phenylbenzophenone, cool to 12°C under the condition of stirring speed of 10-20r / min, cooling speed is 3-5°C / 5min, filter and dry after crystallization, to obtain 3-methyl-4'-phenylbenzophenone particles with specific distribution trend which can achieve the purpose of the present application.

[0041] After the 3-methyl-4'-phenylbenzophenone is dissolved, the particle size of the 3-methyl-4'-phenylbenzophenone particles is controlled by adjusting the stirring speed, the content and adding time of hydrochloric acid, and the cooling speed. The polar effect of hydrochloric acid molecules affects the crystallization speed of 3-methyl-4'-phenylbenzophenone in ethanol, thereby affecting the particle size of 3-methyl-4'-phenylbenzophenone particles.

[0042] The surface tension of plastic film material is low, and the ink fixation performance of the film material is poor. The ink printed on the plastic film material is easy to be removed, and the adhesion of the ink is poor. The plastic film material is easy to bend, which can also cause the ink to be removed or scraped off. The film material is not resistant to the solvent or acid-base additives of the ink, and is easy to spread or dissolve the ink. The distribution of the photoinitiator particles of the ink affects the light absorption capacity and speed, thereby affecting the cross-linking degree of the polymerization reaction of the ink resin and the acrylate monomer, and thus affecting the surface performance of the ink on the plastic film material, such as wear resistance, alcohol resistance and other properties.

[0043] In the present application, it is found that when the photoinitiator meets certain distribution trend, it has the optimal initiation effect on the polymerization of the ink, and the prepared ink has high wear resistance and alcohol resistance. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a particle size distribution diagram of 3-methyl-4'-phenylbenzophenone particles prepared in Example 3. DETAILED DESCRIPTION

[0045] In order to make the person skilled in the art better understand the present application, the present application will be further described in detail below in combination with specific embodiments.

[0046] The raw materials used in the examples and comparative examples are described as follows:

[0047] 3-methyl-4'-phenylbenzophenone: Aldrich reagent;

[0048] Leveling agent: BYK, model: UV3500 (BYK), Germany;

[0049] Antioxidant: BHT, commercially available;

[0050] Dispersant: Solsperse 24000 super dispersant, Lubrizol, USA;

[0051] Resin: polyester acrylate, Changxing, 6353, Taiwan;

[0052] Acrylate monomer: ethoxylated trimethylolpropane triacrylate, Aldrich reagent;

[0053] The remaining raw materials are commercially available.

[0054] Example 1

[0055] In the 3-methyl-4'-phenylbenzophenone powder, ethanol was added, the added mass of ethanol was 5 times that of the 3-methyl-4'-phenylbenzophenone powder, after dissolution, constant temperature stirring was carried out at 65℃ for 30min, the stirring speed was 40r / min, 0.5mol / L hydrochloric acid was added dropwise at the 15th minute, the added content of hydrochloric acid was 2wt% of 3-methyl-4'-phenylbenzophenone, the stirring speed was 20r / min, and the cooling was carried out to 12℃, the cooling speed was 5℃ / 5min, after crystallization, filtration and drying were carried out, and 3-methyl-4'-phenylbenzophenone particles were obtained.

[0056] Example 2

[0057] In the 3-methyl-4'-phenylbenzophenone powder, ethanol was added, the added mass of ethanol was 4 times that of the 3-methyl-4'-phenylbenzophenone powder, after dissolution, constant temperature stirring was carried out at 65℃ for 40min, the stirring speed was 60r / min, 0.5mol / L hydrochloric acid was added dropwise at the 17th minute, the added content of hydrochloric acid was 3wt% of 3-methyl-4'-phenylbenzophenone, the stirring speed was 15r / min, and the cooling was carried out to 12℃, the cooling speed was 5℃ / 5min, after crystallization, filtration and drying were carried out, and 3-methyl-4'-phenylbenzophenone particles were obtained.

[0058] Example 3

[0059] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 6 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 35min, stirring speed is 50r / min, at the 18th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 4wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 15r / min, cooling speed is 3℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0060] Example 4

[0061] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 5.5 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 35min, stirring speed is 55r / min, at the 18th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 2.5wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 15r / min, cooling speed is 4℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0062] Example 5

[0063] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 4.5 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 35min, stirring speed is 45r / min, at the 16th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 3.5wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 13r / min, cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0064] Example 6

[0065] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 5 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 35min, stirring speed is 48r / min, at the 15th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 2wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 16r / min, cooling speed is 4℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0066] Example 7

[0067] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 5.5 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 40min, the stirring speed is 55r / min, at the 20th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 3wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 18r / min, the cooling speed is 3℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0068] Example 8

[0069] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 4.5 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 40min, the stirring speed is 45r / min, at the 15th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 3.5wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 11r / min, the cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0070] Example 9

[0071] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 5 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 40min, the stirring speed is 55r / min, at the 15th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 3wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 15r / min, the cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0072] Example 10

[0073] In the 3-methyl-4'-phenyl benzophenone powder, add ethanol, the added mass of ethanol is 5.5 times of the 3-methyl-4'-phenyl benzophenone powder, after dissolving, constant temperature stirring at 65℃ for 38min, the stirring speed is 52r / min, at the 18th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 2.5wt% of 3-methyl-4'-phenyl benzophenone, cool to 12℃ under the condition of stirring speed of 18r / min, the cooling speed is 4℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenyl benzophenone granules.

[0074] Example 11

[0075] In the 3-methyl-4'-phenyl benzophenone powder, add ethanol, the added mass of ethanol is 4.5 times of the 3-methyl-4'-phenyl benzophenone powder, after dissolving, constant temperature stirring at 65℃ for 38min, the stirring speed is 48r / min, at the 15th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 3.5wt% of 3-methyl-4'-phenyl benzophenone, cool to 12℃ under the condition of stirring speed of 13r / min, the cooling speed is 4℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenyl benzophenone granules.

[0076] Example 12

[0077] In the 3-methyl-4'-phenyl benzophenone powder, add ethanol, the added mass of ethanol is 5 times of the 3-methyl-4'-phenyl benzophenone powder, after dissolving, constant temperature stirring at 65℃ for 38min, the stirring speed is 52r / min, at the 16th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 3wt% of 3-methyl-4'-phenyl benzophenone, cool to 12℃ under the condition of stirring speed of 15r / min, the cooling speed is 4℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenyl benzophenone granules.

[0078] Example 13

[0079] In the 3-methyl-4'-phenyl benzophenone powder, add ethanol, the added mass of ethanol is 4.5 times of the 3-methyl-4'-phenyl benzophenone powder, after dissolving, constant temperature stirring at 65℃ for 30min, the stirring speed is 44r / min, at the 17th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 2wt% of 3-methyl-4'-phenyl benzophenone, cool to 12℃ under the condition of stirring speed of 17r / min, the cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenyl benzophenone granules.

[0080] Example 14

[0081] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 4 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 40min, stirring speed is 40r / min, at the 20th minute, drop in 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 2wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 15r / min, cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0082] Example 15

[0083] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 6 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 30min, stirring speed is 60r / min, at the 20th minute, drop in 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 4wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 20r / min, cooling speed is 3℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0084] Comparative Example 1

[0085] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 4 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 40min, stirring speed is 60r / min, then cool to 12℃ under the condition of stirring speed is 15r / min, cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0086] Comparative Example 2

[0087] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 4 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 40min, stirring speed is 60r / min, at the 20th minute, drop in 0.5mol / L sodium hydroxide, the added content of sodium hydroxide is 3wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed is 15r / min, cooling speed is 5℃ / 5min, after crystallization, filter and dry, get 3-methyl-4'-phenylbenzophenone granules.

[0088] Comparative Example 3

[0089] In 3-methyl-4'-phenylbenzophenone powder, add ethanol, the added mass of ethanol is 4 times of 3-methyl-4'-phenylbenzophenone powder, after dissolving, constant temperature stirring at 65℃ for 45min, the stirring speed is 30r / min, at the 10th minute, drop 0.5mol / L hydrochloric acid, the added content of hydrochloric acid is 6wt% of 3-methyl-4'-phenylbenzophenone, cool to 12℃ under the condition of stirring speed of 5r / min, the cooling speed is 6℃ / 5min, after crystallization, filter and dry, to obtain 3-methyl-4'-phenylbenzophenone particles.

[0090] The particle size of the products prepared in Examples 1-15 and Comparative Examples 1-3 was counted.

[0091] The measuring instrument was a Mastersizer, the prepared sample was all added into the sample pool of the sample feeder, and then the sample was immediately measured after stable shading, and the data was obtained, as shown in Table 1.

[0092] Table 1

[0093] The 3-methyl-4'-phenylbenzophenone particles prepared in Examples 1-15 and Comparative Examples 1-3 were used to prepare inks according to the following methods (as shown in the ink formulation table in Table 2 below):

[0094] The 3-methyl-4'-phenylbenzophenone particles, resin (polyester acrylate), acrylate monomer (ethoxylated trimethylolpropane triacrylate), amine co-initiator (6422TF, Changxing Special Materials (Zhuhai) Co., Ltd.), dispersant (Solsperse 24000 super dispersant, Lubrizol), leveling agent (UV3500(BYK)), and antioxidant (antioxidant BHT) were mixed according to the weight parts shown in Table 2 to obtain an ink.

[0095] The photoinitiator in Experimental Examples 1-15 was the 3-methyl-4'-phenylbenzophenone particles prepared in Examples 1-15, and the photoinitiator in Experimental Examples 16 and 17 was the 3-methyl-4'-phenylbenzophenone particles prepared in Example 3.

[0096] The photoinitiator in Comparative Experimental Examples 1, 2 and 3 was the 3-methyl-4'-phenylbenzophenone particles prepared in Comparative Examples 1, 2 and 3, respectively.

[0097] Table 2 Ink Component Proportion Table (unit: weight parts)

[0098] Ink Performance Test Method

[0099] 1. Gloss test (QB573-83)

[0100] The gloss of the ink is determined according to the method of QB573-83 ink gloss test. The ink is placed on a PET plastic film, and a thin layer of the same size is scraped to form an ink sample. The gloss of the ink sample is measured by 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 gloss of the ink sample (the reflected light flux of the standard surface is 100%). The higher the gloss, the better the gloss performance.

[0101] 2. Abrasion resistance (adhesion)

[0102] The abrasion resistance is determined according to the method of GB 1768-1979 film abrasion resistance test. The specific steps are as follows: the ink is uniformly rolled on a PET plastic film with the same size, and dried for standby use; the sample is fixed on the working turntable of the abrasion tester by using a MCJ-01A type friction tester (provided by Jinan Lanlight Mechatronics Co., Ltd.). The parameters are set to 200 times and 40N. After the test, the sample is taken out and brushed with a brush to remove the floating debris, weighed, and the difference between the front and back weights is the weight loss of the ink. The smaller the weight loss of the ink, the better the abrasion resistance.

[0103] 3. Alcohol resistance

[0104] The sample is immersed in 75% alcohol (25°C) for 12 hours, taken out, washed and dried, and then tested for gloss and abrasion resistance (adhesion) according to the above test method.

[0105] Gloss reduction rate = | (gloss before alcohol treatment - gloss after alcohol treatment) | / gloss before alcohol treatment;

[0106] Adhesion reduction rate = | (adhesion before alcohol treatment - adhesion after alcohol treatment) | / adhesion before alcohol treatment.

[0107] Table 3 test results

[0108] The above data show that the photoinitiator prepared by the present application has high gloss, and the ink prepared by using the photoinitiator with specific particle distribution has good abrasion resistance and alcohol resistance on the surface of the plastic film.

[0109] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown 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: a is in the range of 1.2-2.

0.

2. The photoinitiator according to claim 1, characterized in that: a is in the range of 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 full width at half maximum (FWHM) is 130-310 μm, preferably 190-240 μm.

4. Process for the preparation of a photoinitiator according to any one of claims 1 to 3, characterized in that: comprising the following steps: adding ethanol to the 3-methyl-4'-phenylbenzophenone powder, the added mass of ethanol is 4-6 times that of the 3-methyl-4'-phenylbenzophenone powder, after dissolution, constant temperature stirring at 65°C for 30-40 min, the stirring speed is 40-60 r / min, at the 15th-20th minute, 0.5 mol / L hydrochloric acid is added dropwise, the added content of hydrochloric acid is 2-4 wt% of the 3-methyl-4'-phenylbenzophenone solution, under the condition of stirring speed of 10-20 r / min, cooling to 12°C, the cooling speed is 3-5°C / 5 min, after crystallization, filtering and drying to obtain 3-methyl-4'-phenylbenzophenone particles satisfying the particle size distribution.

5. An ink composition characterized in that: by weight comprising the following ingredients: the photoinitiator according to any one of claims 1-3 2-6 parts; resin 15-50 parts; acrylate monomer 15-30 parts; auxiliary 0.1-3 parts.

6. The ink composition according to claim 5, characterized in that: 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, styrene acrylate.

7. The ink composition according to claim 5, characterized in that: the acrylate monomer is selected from one or more of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ditrimethylolpropane acrylate, tripropyleneglycol diacrylate, propoxylated neopentylglycol diacrylate.

8. The ink composition according to claim 5, characterized in that: the auxiliary is an amine co-initiator.

9. The ink composition according to claim 5, characterized in that: the ink composition further comprises 0.2-2 parts of a dispersing agent, 0.05-0.1 parts of a polymerization inhibitor and 0.1-0.3 parts of an antioxidant.

10. Use of the photoinitiator according to any one of claims 1-3 in the preparation of an ink printed on a plastic product.

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