Cationic photocurable composition for ink and use thereof

Abstract

The present invention provides a cationic photocurable composition for ink and its use. The composition comprises a cationic polymerizable compound, a cationic initiator, and a pigment, the cationic polymerizable compound comprising Compound A-1 and Compound A-2, and the structural formula of Compound A-1 is: [Formula 1] TIFF2025536771000019.tif10170 (wherein R1 represents a methyl group or an ethyl group), and compound A-2 is a vinyl-free polymerizable monomer having a molecular weight of less than 300, with the molecular weight of oxygen in the molecule accounting for 12 to 30% of the molecular weight of the compound, the total content of compounds A-1 and A-2 accounting for 40 wt% to 90 wt% of the total content of the composition, and the weight ratio of compounds A-1 to A-2 is 8:1 to 1:5. As a main component of ink, this composition effectively alleviates the problem of nozzle clogging that occurs with cationic polymerization inks, with particularly remarkable effects on high-precision nozzles, and the patterns formed after curing are clear and uniform, with excellent appearance.

Description

[Technical Field]

[0001] The present invention relates to the technical field of photocuring, and in particular to a cationic photocurable composition for ink and its use. [Background technology]

[0002] In recent years, inkjet printing has become widely used in printing fields such as electronic devices, displays, color filters, and commercial printing because it can create images conveniently and inexpensively. Commonly used inkjet inks mainly include three types: aqueous inkjet inks, solvent-based inkjet inks, and actinic radiation-curable inkjet inks. Most aqueous inks are rarely used because they are not waterproof unless a special oiling or coating is applied after printing. The main component of solvent-based inkjet inks is a volatile organic compound (VOC), an organic compound with a high vapor pressure that is relatively widely used but not environmentally friendly. Actinic radiation-curable inks are widely used because they can rapidly form desired patterns in a non-contact manner and are suitable for printing on a variety of recording media.

[0003] Actinic radiation-curable inkjet inks mainly include two types: radical polymerization inkjet inks using acrylic monomers and cationic polymerization inkjet inks using epoxy compounds. Radical polymerization inkjet inks have a wide range of material options and are widely used in practical applications, but they are significantly affected by oxygen inhibition, limiting the resolution of the images obtained by curing the ink. Cationic polymerization inkjet inks are not inhibited by oxygen and can retain their color for a long time, but they have limited monomer selection, relatively limited pattern resolution, and are prone to nozzle clogging during use.

[0004] Documents such as CN114182545A, JP2007021740A, and JP2003055563A report the use of different cationic photocurable compositions, which have solved the problem of nozzle clogging to some extent, but have not yet effectively solved the problem in the case of high-precision nozzles. Summary of the Invention

[0005] The main object of the present invention is to provide a cationic photocurable composition for ink and use thereof in order to solve the problem that conventional cationic photocurable compositions tend to cause clogging.

[0006] In order to achieve the above object, according to one aspect of the present invention, there is provided a method for producing a polymerizable composition comprising: a cationically polymerizable compound; a cationic initiator; and a pigment, wherein the cationically polymerizable compound comprises Compound A-1 and Compound A-2; The structural formula of compound A-1 is [ka] (wherein R1 represents a methyl group or an ethyl group), Compound A-2 is a polymerizable monomer that does not contain a vinyl group and has a molecular weight of less than 300, in which the molecular weight of oxygen in the molecule accounts for 12 to 30% of the molecular weight of the compound; the total content of compound A-1 and compound A-2 accounts for 40 wt% to 90 wt% of the total content of the composition; The cationic photocurable composition for ink is provided, in which the weight ratio of compound A-1 to compound A-2 is 8:1 to 1:5.

[0007] In a further embodiment, compound A-2 comprises any one or more of the following structures:

[0008] [ka]

[0009] In a further embodiment, the cationically polymerizable compound further comprises a third cationically polymerizable compound, and the content of the third cationically polymerizable compound is 0.1 wt % to 40 wt %, preferably 5 wt % to 30 wt %, of the total amount of the composition. Preferably, the third cationically polymerizable compound comprises any one or more of an alicyclic epoxy compound, an oxetane-based compound, and a vinyl ether-based compound.

[0010] In a further embodiment, the amount of the cationic initiator added is 0.4 wt % to 20 wt %, and preferably 3 wt % to 10 wt %, of the total amount of the composition, and the cationic initiator includes an iodonium salt and / or sulfonium salt photoinitiator, and optionally, the cationic initiator is any one or more selected from the group consisting of diaryliodonium salts of sulfonic acid, triarylsulfonium salts of sulfonic acid, diaryliodonium salts of boric acid, and triarylsulfonium salts of boric acid.

[0011] In a further embodiment, the pigment accounts for 0.5 wt % to 20 wt %, and preferably 2 wt % to 15 wt %, of the total amount of the composition. The pigment is an organic pigment and / or an inorganic pigment. The organic pigment is any one or more selected from the group consisting of perylene, phthalocyanine dye, cyanine pigment, naphthalocyanine pigment, nitroso pigment, azo pigment, diazo pigment, diazo condensation pigment, basic dye pigment, basic blue pigment, blue lake pigment, phloxine pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, carbazole dioxazine violet pigment, alizarin lake pigment, phthalamide pigment, carmine lake pigment, tetrachloroisoindolinone pigment, perinone pigment, anthraquinone pigment, and quinophthalone pigment. The inorganic pigment is any one or more selected from the group consisting of titanium oxide, iron oxide, aluminum oxide, silicon oxide, carbon black pigment, metal sulfide, and metal chloride.

[0012] In a further embodiment, the composition further comprises a sensitizer, and the content of the sensitizer in the composition is 0.1 wt % to 15 wt %, and preferably 3 wt % to 8 wt %. Preferably, the sensitizer is any one or more selected from the group consisting of thioxanthone compounds, xanthone compounds, acridine compounds, anthracene compounds, and coumarin compounds, and more preferably, the sensitizer is any one or more selected from the group consisting of anthracene compounds and thioxanthone compounds.

[0013] In a further embodiment, the total content of compound A-1 and compound A-2 accounts for 50 wt% to 90 wt% of the total content of the composition, and the ratio of the amounts of compound A-1 to compound A-2 used is 8:5 to 2:5.

[0014] In a further embodiment, the composition further comprises an auxiliary agent, and the auxiliary agent includes any one or more of a leveling agent, a dispersing agent, a curing agent, a surfactant, an antifoaming agent, and a storage stabilizer.

[0015] In a further embodiment, the viscosity of the composition is less than 50 mPa·s, and preferably the viscosity is 2 to 30 mPa·s.

[0016] According to another aspect of the present invention there is provided the use of any of the compositions described above in an ink.

[0017] Furthermore, the substrate used for the ink includes any one of a thin film, glass, and plastic, and the spray thickness of the composition is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm.

[0018] By applying the technical solution of the present invention and adopting a combination of cationic polymers having specific structures, it is possible to form an appropriate ink with a relatively stable viscosity. The researchers of the present invention have discovered by chance that by using a cationic polymerizable compound having the above structure as the main component of the ink, the problem of cationic polymerization ink being prone to nozzle clogging can be effectively alleviated, with the effect being particularly remarkable in the case of high-precision nozzles. Furthermore, the cationic photocurable composition for ink of the present invention has been found to form clear and uniform patterns after curing, has a fast curing speed, strong adhesion, and excellent appearance. DETAILED DESCRIPTION OF THE INVENTION

[0019] In addition, the embodiments and features of the embodiments in the present application may be combined with each other as long as there is no contradiction. The present invention will be described in detail below with reference to the combined embodiments.

[0020] As analyzed in the Background Art section of the present application, there is a problem in the prior art that cationic photocurable compositions are prone to nozzle clogging, and this problem is particularly pronounced in the case of high-precision nozzles. To solve this problem, the present invention provides a cationic photocurable composition for ink and use thereof.

[0021] According to one exemplary embodiment of the present application, there is provided a cationic photocurable composition for ink, the composition comprising a cationic polymerizable compound, a cationic initiator, and a pigment, the cationic polymerizable compound comprising any combination of Compound A-1 and Compound A-2, and Compound A-1 having a structural formula represented by the formula: [ka] (wherein R1 represents a methyl group or an ethyl group), compound A-2 is a polymerizable monomer that does not contain a vinyl group and has a molecular weight of less than 300, and the molecular weight of oxygen in the molecule accounts for 12 to 30% of the molecular weight of the compound, the total content of compound A-1 and compound A-2 accounts for 40 wt% to 90 wt% of the total content of the composition, and the weight ratio of compound A-1 to compound A-2 in the composition is 8:1 to 1:5.

[0022] The present invention employs a combination of cationic polymers having specific structures to form an ink with a relatively stable viscosity and suitable properties. Researchers of the present invention have discovered by chance that the use of a cationic polymerizable compound having the above structure as the main component of the ink effectively alleviates the problem of cationic polymerization inks being prone to nozzle clogging, with the effect being particularly pronounced in the case of high-precision nozzles. Furthermore, the present invention's cationic photocurable ink composition forms clear and uniform patterns after curing, has a fast curing speed, strong adhesion, and excellent appearance.

[0023] From the prior art, a polymerizable monomer satisfying the above conditions can be obtained as Compound A-2 and applied to the cationic photocurable composition for ink of the present application. In some preferred embodiments of the present application, Compound A-2 includes one or more selected from the group consisting of the following structures:

[0024] [ka]

[0025] For example, the weight ratio of the compound A-1 to the compound A-2 is 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, or any range therebetween. The total content of the compound A-1 and the compound A-2 is any value between 40 wt% and 90 wt% of the total content of the composition, for example, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or any range therebetween.

[0026] In addition to Compound A-1 and Compound A-2, the cationically polymerizable compound may further include another cationically polymerizable compound known in the prior art. In some embodiments of the present application, the other cationically polymerizable compound is referred to as a third cationically polymerizable compound, and the content of the third cationically polymerizable compound is 0.1 wt % to 40 wt %, preferably 5 wt % to 30 wt %, for example, 10 wt %, 15 wt %, 20 wt %, or 25 wt %, of the total amount of the composition. The addition of the third cationically polymerizable compound can further improve the overall performance of the cationic photocurable composition for ink and broaden its range of application.

[0027] The third cationically polymerizable compound may be selected from conventional compounds, for example, any one or more compounds selected from the group consisting of alicyclic epoxy compounds, oxetane compounds, and vinyl ether compounds.

[0028] The cationically polymerizable compound may further contain a resin, for example, an acrylic resin or a polyurethane resin, which may be selectively added as needed, but is not limited in the present application.

[0029] The type and amount of the cationic initiator may be selected from conventional techniques. In some preferred embodiments of the present application, the amount of cationic initiator added is 0.4 wt% to 20 wt%, preferably 3 wt% to 10 wt%, of the total amount of the composition, which can further improve curing performance. In some embodiments of the present application, the cationic initiator includes an iodonium salt and / or sulfonium salt photoinitiator, such as one or more selected from the group consisting of diaryliodonium salts of sulfonic acid, triarylsulfonium salts of sulfonic acid, diaryliodonium salts of boric acid, and triarylsulfonium salts of boric acid.

[0030] Examples of the cationic photoinitiator include bis(dodecylphenyl)iodonium hexafluoroarsenate, bis(dodecylphenyl)iodonium hexafluoroantimonate, dialkylphenyliodonium hexafluoroantimonate, diaryliodonium salts of perfluoroalkylsulfonic acids, diaryliodonium salts of perfluorobutanesulfonic acid, diaryliodonium salts of perfluoroethanesulfonic acid, diaryliodonium salts of perfluorooctanesulfonic acid, diaryliodonium salts of trifluoromethanesulfonic acid, diaryliodonium salts of p-toluenesulfonic acid, diaryliodonium salts of dodecylbenzenesulfonic acid, diaryliodonium salts of benzenesulfonic acid, diaryliodonium salts of 3-nitrobenzenesulfonic acid, perfluoro Examples of structures that may be mentioned include triarylsulfonium salts of butanesulfonic acid, triarylsulfonium salts of perfluoroethanesulfonic acid, triarylsulfonium salts of perfluorooctanesulfonic acid, triarylsulfonium salts of trifluoromethanesulfonic acid, triarylsulfonium salts of p-toluenesulfonic acid, triarylsulfonium salts of dodecylbenzenesulfonic acid, triarylsulfonium salts of benzenesulfonic acid, triarylsulfonium salts of 3-nitrobenzenesulfonic acid, diaryliodonium salts of perhaloarylboronic acid, and triarylsulfonium salts of perhaloarylboronic acid. One or more of these may be selected and added to the composition, or one or more of these may be selected and used simultaneously with another type of cationic photoinitiator.

[0031] The pigment in the cationic photocurable composition for ink of the present application does not have any special requirements as a colorant and may be selected from conventional techniques. In some embodiments of the present application, the pigment is present in an amount of 0.5 wt% to 20 wt% of the total amount of the composition, for example, 1.2 wt%, 1.8 wt%, 2.5 wt%, 3.5 wt%, 4.5 wt%, 5.5 wt%, 6.5 wt%, 7.5 wt%, 8.5 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, or 18 wt%, and preferably 2 wt% to 15 wt%, which can better balance the chromaticity and curing performance of the ink.

[0032] The pigments may be of any color, such as black, blue, brown, cyan, green, white, purple, magenta, red, orange, and yellow, as well as mixtures thereof.

[0033] The pigment may be an organic pigment and / or an inorganic pigment. For example, organic pigments include perylene, phthalocyanine dyes (e.g., phthalocyanine green, phthalocyanine blue), cyanine pigments (e.g., Cy3, Cy5, and Cy7), naphthalocyanine pigments, nitroso pigments, azo pigments, diazo pigments, diazo condensation pigments, basic dye pigments, basic blue pigments, blue lake pigments, phloxine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, carbazole dioxazine violet pigments, alizarin lake pigments, and phthalamide. The inorganic pigment is any one or more selected from the group consisting of titanium oxides (e.g., titanium dioxide, conductive titanium dioxide), iron oxides (e.g., red iron oxide, yellow iron oxide, black iron oxide, and transparent iron oxide), aluminum oxide, silicon oxide, carbon black pigments, metal sulfides, and metal chlorides.

[0034] In some embodiments of the present application, the composition further contains a sensitizer to further improve the photosensitivity of the composition or to meet the requirement of being photocurable with a long wavelength light source, particularly a UV-LED light source. The content of the sensitizer in the cationic photocurable composition for ink is 0.1 wt% to 15 wt%, preferably 3 wt% to 8 wt%.

[0035] The sensitizer is at least one selected from the group consisting of thioxanthone compounds, xanthone compounds, acridine compounds, anthracene compounds, and coumarin compounds. In some preferred embodiments of the present application, the sensitizer is at least one selected from the group consisting of anthracene compounds and thioxanthone compounds, such as JRCure-1105 (ITX) and JRCure-1106 (DETX) manufactured by Tianjin Jiuri New Materials Co., Ltd., and PSS303, PSS306, PSS506, PSS510, PSS513, PSS515, PSS402, PSS403, and PSS603 manufactured by Changzhou Strong Electronic New Materials Co., Ltd.

[0036] In some embodiments, the total content of Compound A-1 and Compound A-2 in the cationic photocurable ink composition is 50 wt% to 90 wt%, for example, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, or 85 wt% of the total composition. When the weight ratio of Compound A-1 to Compound A-2 in the composition is 8:5 to 2:5, for example, 4:3, 1:1, 2:3, or 1:2, the pattern formed after curing is better, the probability of nozzle clogging is further reduced, and the composition is suitable for inkjet printing with higher nozzle precision. Furthermore, researchers have found that the higher the content of Compound A-1 and Compound A-2 in the cationic photocurable ink composition, the more stable the viscosity of the composition, the better the ink's clogging resistance, and the better the curing speed and pattern appearance.

[0037] Depending on the requirements of the application environment of the product, one or more organic and / or inorganic auxiliaries commonly used in this field, such as leveling agents, dispersants, curing agents, surfactants, antifoaming agents, and storage stabilizers, may be selectively added to the cationic photocurable composition for ink of the present application. The specific components and amounts of the auxiliaries may be found in the prior art, but further explanation is omitted here.

[0038] The viscosity of the cationic photocurable composition for ink of the present application is not particularly limited, and when the composition forms a coating layer by inkjet printing, the viscosity of the composition is usually suitably 50 mPa s or less, preferably 2 to 30 mPa s, and more preferably 3 to 15 mPa s. The viscosity of the composition of the present invention is well controlled during storage, and no thickener or thinning agent needs to be added.

[0039] The cationic photocurable composition for ink of the present application is not particularly limited in the form of the initiation energy source, and can undergo polymerization reaction under any energy radiation such as ultraviolet light, visible light, infrared light, electron beam, or laser, thereby achieving rapid curing. Illustratively, the energy source may be an ultra-high pressure mercury lamp, high pressure mercury lamp, medium pressure mercury lamp, mercury xenon lamp, low pressure mercury lamp, metal halide lamp, xenon lamp, deuterium lamp, chemical lamp, LED lamp, fluorescent lamp, tungsten lamp, Nd-YAG triple harmonic laser, He-Cd laser, nitrogen laser, Xe-Cl excimer laser, Xe-F excimer laser, semiconductor pumped solid state laser, i-ray, h-ray, g-ray or other actinic ray, and the composition may be cured by further using energy such as electron beam, α-ray, β-ray, γ-ray, X-ray and neutron beam. Preferably, a mercury lamp, ultraviolet lamp or UV-LED lamp having a wavelength range of 200 to 500 nm is used, and the irradiation energy is preferably 20 to 1000 mJ / cm. 2 When cured with a long wavelength energy source, a sensitizer is preferably added to the composition to improve the photosensitivity of the composition.

[0040] A radiation-curable inkjet ink can be obtained by uniformly mixing the components of the cationic photocurable composition for ink of the present application, and the specific preparation process may refer to methods for preparing radiation-curable compositions in the prior art. Typically, the inkjet ink is obtained by blending, pre-dispersing, grinding, and filtering (filtering through a screen of a predetermined size to obtain a product with a desired particle size) under conditions of constant temperature and humidity and avoiding a radiation light source.

[0041] According to another exemplary embodiment of the present application, there is provided use of any of the above-described cationic photocurable compositions for ink in ink.

[0042] When the cationic photocurable composition for ink of the present application is applied to ink, the problem of cationic polymerization ink being prone to nozzle clogging can be effectively alleviated, and the effect is particularly remarkable in the case of high-precision nozzles. Furthermore, the cationic photocurable composition for ink of the present application forms clear and uniform patterns after curing, has strong adhesion, and has excellent appearance.

[0043] The thickness of the cured coating layer of the pattern sprayed with the cationic photocurable ink composition of the present application can be adjusted according to conventional techniques or the intended use. Preferably, the thickness of the sprayed pattern is 0.1 to 10 μm, and particularly preferably 0.5 to 5 μm, so that the formed coating layer is relatively uniform and advantageous for cost control. If the ink coating layer is too thin, there is a risk that the coating layer will not be formed uniformly, making it difficult to optionally print accurately according to the design. If the thickness is too thick, a large amount of printing ink will be consumed in the coating layer, which may increase costs and is disadvantageous to uniform application, and the coating layer will become brittle and prone to layer separation.

[0044] When the cationic photocurable composition is used as an ink, the application method thereof may refer to the prior art and is not particularly limited. In addition to the inkjet printing method, other well-known methods such as a dipping method, an air doctor coating method, a curtain coating method, a roll coater method, a die coating method, and a wire bar coating method may also be employed.

[0045] When the cationic photocurable composition is used as an ink, the substrate to be used is not particularly limited, and examples of the substrate include thin films, glass, and plastics. Depending on the substrate material selected, a surface treatment such as corona treatment may be selectively performed.

[0046] The beneficial effects of the present invention will be further explained below in combination with examples and comparative examples.

[0047] 1. Ink Preparation According to the formulations of the Examples and Comparative Examples in Tables 1 and 2, the ingredients were stirred at a constant speed using a high-speed stirrer under yellow light lamp conditions for 1 hour, then polished in a sand mill, and then filtered through a screen with a particle size of 1 μm to obtain an ink composition. The numbers shown for each Example and Comparative Example in the tables are all parts by weight.

[0048] [Table 1]

[0049] [Table 2]

[0050] In the table, the components represented by alphabets are specifically as follows: A11 to A16 are compounds represented by compound A-1 or similar compounds, A21 to A24 are compounds represented by compound A-2 or similar compounds, B1 and B2 are third cationically polymerizable compounds, C1 and C2 are cationic initiators, D1 and D2 are pigments, and E is a sensitizer.

[0051] A-11: [ka] (Prepared by myself with reference to the synthesis method disclosed in JP1995017958A) A-12: [ka] (Prepared by myself with reference to the synthesis method disclosed in JP1995017958A) A-21: [ka] (Prepared by myself with reference to the synthesis method disclosed in US3452054A) A-22: [ka] (Prepared by myself with reference to the synthesis method disclosed in JP3047800B2) A-13: [ka] (Prepared by myself with reference to the synthesis method disclosed in JP2000063522A) A-14: [ka] (Prepared by myself with reference to the synthesis method disclosed in JP1999315181A) A-15: [ka] (Prepared by myself with reference to the synthesis method disclosed in US3105838A) A-16: [ka] (Symbol: THM209-1) A-23: 4,4-bis[(3-ethyl-3-oxetane)methoxymethyl]biphenyl (cass: 358365-48-7) A-24: 3-hydroxy-3-hydroxymethyloxetane (cas: 16563-93-2) B1: Poly[(2-oxiranyl)-1,2-cyclohexanediol] 2-ethyl-2-(hydroxymethyl)-1,3-propanediol ether (3:1) (Code: TTA3150) B2: 4,4-bis[(3-ethyl-3-oxetane)methoxymethyl]biphenyl (Changzhou Power Electronic New Materials Co., Ltd.) C1: Bis(dodecylphenyl)iodonium hexafluoroantimonate (Changzhou Powerful New Electronic Materials Co., Ltd.) C2: Triphenylsulfonium hexafluorophosphate (Changzhou Power Electronic New Materials Co., Ltd.) D1: Inorganic carbon black (Clariant Chemicals (China) Co., Ltd.) D2: Titanium White (Shanghai Shucan Industrial Co., Ltd.) E: 2-ethylanthracene-9,10-di(3-cyclohexylpropionate) (symbol: PSS506).

[0052] 2. Ink hardening and drying speed measurement The ink to be measured in each example and comparative example is printed using a Shotoku solventless inkjet printer (model number: A380), and an LED lamp with a wavelength of 395 nm is added to the printer as a radiation light source. The ink to be measured is transferred onto a PET thin film (Lakukai's general industrial thin film FP2) using the inkjet printer, with a printing thickness of 5 μm and the power of the LED light source set to 20 watts / cm². 2 Let's say.

[0053] After the light irradiation was completed, the sample was left for 24 hours, and the surface curing speed was evaluated using the finger touch method in GB / T 1728-1979, a coating drying time test standard. Specifically, the coating layer was lightly touched with a finger to determine whether the surface was dry, whether it was smooth, non-sticky, and whether no fingerprints were left when pressed. The drying speed was expressed as the maximum linear speed (m / min) required to achieve a surface drying effect, and the measurement results are shown in Table 3. The curing and drying speed can reflect the activity of the composition; a higher curing and drying speed indicates a faster curing speed and a more active composition.

[0054] 3. Evaluation of adhesion of cured ink layer and appearance of printed matter The linear speeds of the inkjet printer (Inside) were set to 220 m / min and 150 m / min, respectively, and the substrate was a PET thin film (JPC-P1-125), the printing thickness was set to 5 μm, and the irradiation energy of the 395 nm LED light source was set to 20 mJ / cm. 2 After exposure, the print was left for 24 hours, and basic performance such as adhesion of the cured coating layer and appearance of the printed matter was evaluated. The evaluation results are shown in Table 3.

[0055] (1) Coating layer adhesion measurement According to "GB / T9286-1998 Paints and varnishes - Cross-cut test of coating film", the 100-mass cross-cut method was adopted, and the QFH coating film cross-cut device was used to measure the adhesion to the substrate. The specific implementation method is as follows:

[0056] Using a knife conforming to "GB / T9286-1998 Paints and varnishes - Cross-cut test for coating films," the surface of the coating layer was cut, making sure to penetrate the substrate surface each time. The surface of the coating layer was then cleaned with a soft brush. After that, adhesive tape was applied to the coating layer, ensuring that the adhesive tape was in full contact with the coating layer. Finally, the adhesive tape was peeled off from the surface of the coating layer, and the results were evaluated. The basis for the judgment is shown below, and the specific evaluation results are shown in Table 3.

[0057] Level 0: The cutting edge is completely smooth and there is no flaking of the mass.

[0058] Level 1: Minor coating layer delamination at the intersection of the cut edges, but the affected intersection does not clearly exceed 5% of the cut area.

[0059] Level 2: Delamination of the coating layer is observed at the intersection of the cut and / or along the edge of the cut, with the cut area at the affected intersection clearly exceeding 5% but not exceeding 15%.

[0060] Level 3: Part or all of the coating layer has detached in large pieces along the cut edge and / or in different parts of the mass, with the cut area of ​​the affected intersection clearly exceeding 15% but not exceeding 35%.

[0061] Level 4: The coating layer has detached in large pieces along the cut edge and / or some masses have detached partially or completely, with the cut area of ​​the affected intersection clearly exceeding 35% but not exceeding 65%.

[0062] Level 5: The degree of peeling exceeds level 4.

[0063] (2) Appearance evaluation of printed matter In accordance with GB / T 7707-2008 inkjet decorative print standards, inkjet printing with a depth of 10-18 μm is used. After leaving the print for 24 hours, it is placed under a sample observation light source conforming to the requirements of CY / T 3 and visually inspected. The print is neat and clean, with no obvious ink stains, defects, or doctor marks. The characters are clearly printed completely with no defects or deformations. Even characters smaller than 7.5P do not affect visibility. The edges of solid print are smooth and clean. The ink color is uniform with no obvious watermarks. The printing gradation transitions are smooth with no obvious tonal jumps. The halftone dots are clear and uniform with no obvious deformations or defects. The printing color meets the requirements of the proof print sample. Conversely, if any of the above conditions are not met, it is marked as failing.

[0064] (3) Evaluation of clogging resistance The nozzles used in the test are Nozzle A (Model number: KJ4A-0300 (4PL, 112.35 mm)) and Nozzle B (Model number G5I, (3.5PL, 10-15 mm)).

[0065] The ink usage conditions of each example and comparative example were observed for the two types of nozzles when they were in operation and when they were not initially in operation, and the evaluation method was as follows.

[0066] <1> If it works, According to the above test formulation, 3x3cm square test patterns were drawn in a row along the vertical and horizontal directions on a PET film (JPC-P1-125), and each test pattern was drawn with a 3cm interval between each other. After continuous drawing for 2 hours, the basic conditions of nozzle A (1328 holes of KJ4A-0300) and nozzle B (1280 holes of G5I) in the nozzle row were checked, and the evaluation criteria were as follows:

[0067] A: There are no nozzles that do not spray. B: Nozzles that do not spray are 2% or less C: Nozzles that do not spray are more than 2% but less than 5% D: More than 5% of nozzles do not spray.

[0068] <2> If it doesn't work initially, According to the above test formulation, the inks of each example and comparative example were placed in nozzles of different model numbers, and the viscosity changes of the compositions were recorded after leaving them for 8 hours and 48 hours, respectively. After leaving the compositions for 48 hours, operation was carried out and after 2 hours of continuous drawing, the conditions of nozzles A and B were observed, and the evaluation criteria were as follows:

[0069] A: There are no nozzles that do not spray. B: Nozzles that do not spray are 2% or less C: Nozzles that do not spray are more than 2% but less than 5% D: More than 5% of nozzles do not spray.

[0070] [Table 3]

[0071] As is clear from the performance evaluation results in Table 3, the cationic photocurable composition of the present invention has excellent curing performance, and even when left for a long time, there is almost no effect on viscosity. Nozzle clogging occurs whether it is operated continuously or intermittently. This shows clear effects, particularly in high-precision nozzle applications, and is expected to be widely applied.

[0072] As can be seen from the above description, the examples described in the present invention have the following technical effects: By applying the cationic photocurable composition for ink of the present application to ink, it is possible to effectively alleviate the problem of cationic polymerization inks being prone to nozzle clogging, a problem that is particularly noticeable in the case of high-precision nozzles, and the cationic photocurable composition for ink of the present application forms clear and uniform patterns after curing, has strong adhesion, and has excellent appearance.

[0073] The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Those skilled in the art will recognize that the present invention may have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. a cationic polymerizable compound, a cationic initiator, and a pigment, wherein the cationic polymerizable compound includes Compound A-1 and Compound A-2; The structural formula of the compound A-1 is 【Chemistry 1】 (However, R １ represents a methyl group or an ethyl group; The compound A-2 is a polymerizable monomer having a molecular weight of less than 300, in which the molecular weight of oxygen in the molecule accounts for 12 to 30% of the molecular weight of the compound, and does not contain a vinyl group; the total content of the compound A-1 and the compound A-2 accounts for 40 wt % to 90 wt % of the total content of the composition; A cationic photocurable composition for ink, characterized in that the weight ratio of compound A-1 to compound A-2 is 8:1 to 1:

5.

2. The composition according to claim 1, wherein the compound A-2 comprises one or more of the following structures: 【Chemistry 2】

3. the cationically polymerizable compound further includes a third cationically polymerizable compound, and the content of the third cationically polymerizable compound is 0.1 wt % to 40 wt %, preferably 5 wt % to 30 wt %, of the total amount of the composition; The composition according to claim 1, wherein the third cationically polymerizable compound preferably includes one or more of an alicyclic epoxy compound, an oxetane-based compound, and a vinyl ether-based compound.

4. the amount of the cationic initiator added is 0.4 wt % to 20 wt %, preferably 3 wt % to 10 wt %, of the total amount of the composition, and the cationic initiator comprises an iodonium salt and / or sulfonium salt photoinitiator; 2. The composition of claim 1, wherein the cationic initiator is optionally one or more selected from the group consisting of diaryliodonium salts of sulfonic acids, triarylsulfonium salts of sulfonic acids, diaryliodonium salts of boric acids, and triarylsulfonium salts of boric acids.

5. the pigment is present in an amount of 0.5 wt % to 20 wt %, preferably 2 wt % to 15 wt %, of the total amount of the composition, and the pigment is an organic pigment and / or an inorganic pigment; the organic pigment is at least one selected from the group consisting of perylene, a phthalocyanine dye, a cyanine pigment, a naphthalocyanine pigment, a nitroso pigment, an azo pigment, a diazo pigment, a diazo condensation pigment, a basic dye pigment, a basic blue pigment, a blue lake pigment, a phloxine pigment, a quinacridone pigment, an isoindolinone pigment, a dioxazine pigment, a carbazole dioxazine violet pigment, an alizarin lake pigment, a phthalamide pigment, a carmine lake pigment, a tetrachloroisoindolinone pigment, a perinone pigment, an anthraquinone pigment, and a quinophthalone pigment; 2. The composition according to claim 1, wherein the inorganic pigment is at least one selected from the group consisting of titanium oxide, iron oxide, aluminum oxide, silicon oxide, carbon black pigment, metal sulfide, and metal chloride.

6. the composition further comprises a sensitizer, and the content of the sensitizer in the composition is 0.1 wt % to 15 wt %, preferably 3 wt % to 8 wt %; The composition according to claim 1, wherein the sensitizer is preferably one or more selected from the group consisting of thioxanthone-based compounds, xanthone-based compounds, acridine-based compounds, anthracene-based compounds, and coumarin-based compounds, and more preferably one or more selected from the group consisting of anthracene-based compounds and thioxanthone-based compounds.

7. The composition according to any one of claims 1 to 6, wherein the total content of the compound A-1 and the compound A-2 accounts for 50 wt% to 90 wt% of the total content of the composition, and the ratio of the amounts of the compound A-1 to the compound A-2 used is 8:5 to 2:

5.

8. The composition according to any one of claims 1 to 6, further comprising an auxiliary agent, and the auxiliary agent comprises any one or more of a leveling agent, a dispersant, a curing agent, a surfactant, an antifoaming agent, and a storage stabilizer.

9. 7. The composition according to any one of claims 1 to 6, characterized in that the viscosity of the composition is less than 50 mPa·s, preferably between 2 and 30 mPa·s.

10. Use of the composition according to any one of claims 1 to 9 in ink.

11. The substrate used in the ink includes any one of a thin film, glass, and plastic; Use according to claim 10, characterized in that the spray thickness of the composition is preferably between 0.1 and 10 μm, more preferably between 0.5 and 5 μm.

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