Cationic photocurable composition for ink and use thereof

Abstract

The application provides a cationic photocuring composition for ink and application thereof. The composition comprises a cationic polymerizable compound, a cationic initiator and a pigment, the cationic polymerizable compound comprises compound A-1 and compound A-2; wherein the structural formula of compound A-1 is R1 represents methyl or ethyl; compound A-2 is a polymerizable monomer without vinyl, the molecular weight of which is less than 300, and the molecular weight of oxygen in the molecule accounts for 12-30% of the molecular weight of the compound; the sum of the content of compound A-1 and compound A-2 accounts for 40wt%-90wt% of the total content of the composition; and the weight ratio of compound A-1 and compound A-2 is 8:1-1:5. The above-mentioned composition as the main component of the ink can effectively improve the problem that the cationic polymerization type ink is easy to block the nozzle, especially for high-precision nozzles, the effect is particularly significant, the pattern formed after curing is clear and uniform, and the appearance performance is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocuring technology, in particular to a cationic photocuring composition for ink and application thereof. BACKGROUND

[0002] In recent years, inkjet printing is being widely applied in printing fields such as electronic devices, display devices, color filters, commercial printing, etc. due to its ability to simply and cheaply produce images. Commonly used inkjet inks mainly include three types: water-based inkjet ink, solvent-based inkjet ink and active energy ray-curable inkjet ink. Most water-based inks cannot be used without special overcoating or film coating after printing to prevent water, and solvent-based inkjet ink mainly contains volatile organic compounds (VOC), which are organic compounds with high vapor pressure and are relatively widely used but not environmentally friendly. Among them, active energy ray-curable inkjet ink can be widely used to form the required pattern in a non-contact manner and quickly print on various recording media.

[0003] Active energy ray-curable inkjet ink mainly includes two types: free radical polymerization type inkjet ink using acrylic monomers and cationic polymerization type inkjet ink using epoxy compounds. Free radical polymerization type inkjet ink is widely used in practical applications due to its wide range of material selection, but it is greatly affected by oxygen inhibition, and the image fineness obtained after ink curing is limited. Cationic polymerization type inkjet ink is not hindered by oxygen, and the color remains durable, but the selection of monomers is limited, the pattern fineness is also relatively limited, and in use, it is easy to block the nozzle.

[0004] CN114182545A, JP2007021740A, JP2003055563A and other documents report the application of different cationic photocuring compositions, which to some extent solve the problem of nozzle blockage, but for high-precision nozzles, the problem has not been effectively solved. SUMMARY

[0005] The main purpose of the present application is to provide a cationic photocuring composition for ink and application thereof to solve the problem of easy nozzle blockage of the existing cationic photocuring composition.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a cationic photocuring composition for ink is provided, which comprises: a cationic polymerizable compound, a cationic initiator and a pigment, the cationic polymerizable compound comprising compound A-1 and compound A-2; wherein the structural formula of compound A-1 is R1 represents methyl or ethyl; compound A-2 is a polymerizable monomer without a vinyl group with a molecular weight less than 300 and the molecular weight of oxygen in the molecule accounts for 12-30% of the molecular weight of the compound;

[0007] The sum of the content of compound A-1 and compound A-2 is 40wt% to 90wt% of the total content of the composition; the weight ratio of compound A-1 and compound A-2 is 8:1 to 1:5.

[0008] Further, compound A-2 includes any one or more selected from the following structures:

[0009] Further, the above-mentioned cationic polymerizable compound further includes a third cationic polymerizable compound, the content of the third cationic polymerizable compound is 0.1wt% to 40wt% of the total amount of the composition, preferably 5wt% to 30wt%; preferably, the third cationic polymerizable compound includes any one or more of alicyclic epoxy compound, oxetane compound and vinyl ether compound.

[0010] Further, the addition amount of the cationic initiator is 0.4wt% to 20wt% of the total amount of the composition, preferably 3wt% to 10wt%, the cationic initiator includes iodonium salt and / or sulfonium salt photoinitiator; optionally, the above-mentioned cationic initiator is selected from any one or more of diaryliodonium sulfonate, triarylsulfonium sulfonate, diaryliodonium borate and triarylsulfonium borate.

[0011] Further, the pigment is 0.5wt% to 20wt% of the total amount of the composition, preferably 2wt% to 15wt%, the pigment is organic pigment and / or inorganic pigment; the organic pigment is selected from any one or more of perylene, phthalocyanine dye, cyanine pigment, naphthalocyanine pigment, nitroso pigment, azo pigment, diazo pigment, diazo condensation pigment, basic dye pigment, basic blue pigment, blue indigo pigment, root red pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, carbazole dioxazine violet pigment, alizarin lake pigment, phthalimide pigment, cochineal lake pigment, chlorinated isoindolinone pigment, perinone pigment, anthraquinone pigment and quinophthalone pigment; the inorganic pigment is selected from any one or more of titanium oxide, iron oxide, aluminum oxide, silicon oxide, carbon black pigment, metal sulfide and metal chloride.

[0012] Further, the composition further includes a sensitizer, the content of the sensitizer in the composition is 0.1wt% to 15wt%, preferably 3wt% to 8wt%; preferably, the sensitizer is selected from any one or more of thioxanthone compound, xanthone compound, acridine compound, anthracene compound and coumarin compound; more preferably, the sensitizer is selected from any one or more of anthracene compound and thioxanthone compound.

[0013] Further, the sum of the content of the compound A-1 and the compound A-2 accounts for 50wt% to 90wt% of the total content of the composition, and the ratio of the amount of the compound A-1 to the compound A-2 is 8:5 to 2:5.

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

[0015] Further, the viscosity of the composition is less than 50mPa·s; preferably, the viscosity is 2 to 30mPa·s.

[0016] According to another aspect of the present application, the composition of any one of the above is applied in an ink.

[0017] Further, the substrate used by the ink comprises any one of a film, glass, and plastic; preferably, the spraying thickness of the composition is 0.1 to 10μm, and more preferably, 0.5 to 5μm.

[0018] By using the cationic polymer composition with the specific structure, the ink with stable and suitable viscosity can be formed. The researchers of the present application accidentally found that the cationic polymer compound with the above structure can be used as the main component of the ink, which can effectively improve the problem that the cationic polymer ink is easy to block the nozzle, especially for the high-precision nozzle. Moreover, the pattern formed by the cationic photocuring composition of the present application has the advantages of clearness, uniformity, fast curing speed, strong adhesion, and excellent appearance performance. DETAILED DESCRIPTION

[0019] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0020] As analyzed in the background art of the present application, the cationic photocuring composition in the prior art is easy to block the nozzle, especially for the high-precision nozzle. In order to solve this problem, the present application provides a cationic photocuring composition for ink and the application thereof.

[0021] According to a typical embodiment of the present application, a cationic photocuring composition for ink is provided, which comprises: a cationic polymer compound, a cationic initiator, and a pigment, wherein the cationic polymer compound comprises any combination of a compound A-1 and a compound A-2; wherein the structural formula of the compound A-1 is R1 represents a methyl group or an ethyl group; compound A-2 is a polymerizable monomer having a molecular weight of less than 300 and having a molecular weight of oxygen accounting for 12-30% of the molecular weight of the compound; the content of compound A-1 and compound A-2 together accounts for 40wt%-90wt% of the total content of the composition; wherein the weight ratio of compound A-1 and compound A-2 in the above composition is 8:1-1:5.

[0022] The present application can form an ink with relatively stable and suitable viscosity by using a cationic polymer combination with a specific structure; the researchers of the present application accidentally found that using a cationic polymer compound with the above structure as the main component of the ink can effectively improve the problem that the cationic polymer ink is prone to clogging the nozzle, especially for high-precision nozzles, and the pattern formed after the cationic photocuring composition of the present application is cured is clear, uniform, fast in curing speed, strong in adhesion, and excellent in appearance performance.

[0023] A polymerizable monomer meeting the above conditions can be found in the prior art and applied to the cationic photocuring composition of the present application as compound A-2. In some preferred embodiments of the present application, the above compound A-2 includes any one or more selected from the following structures:

[0024] For example, the weight ratio of compound A-1 and 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 between any two of them. The content of compound A-1 and compound A-2 together accounts for 40wt%-90wt% of the total content of the composition, for example, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or any range between any two of them.

[0025] In addition to compound A-1 and compound A-2, the above cationic polymer compound can also include other cationic polymer compounds in the prior art. In some embodiments of the present application, the other cationic polymer compound is referred to as a third cationic polymer compound, and the content of the third cationic polymer compound is 0.1wt%-40wt% of the total amount of the composition, preferably 5wt%-30wt%, such as 10wt%, 15wt%, 20wt%, 25wt%. By adding the third cationic polymer compound, the comprehensive performance of the cationic photocuring composition for ink can be further improved, and the application range can be expanded.

[0026] The third cationic polymerizable compound can be selected from the prior art, such as any one or more selected from alicyclic epoxy compounds, oxetane compounds and vinyl ether compounds.

[0027] The cationic polymerizable compound described above can also contain a resin, such as an acrylic resin, a polyurethane resin, which can be optionally added as needed, without limitation in the present application.

[0028] The type and amount of the cationic initiator described above can be selected from the prior art. In some preferred embodiments of the present application, the cationic initiator is added in an amount of 0.4 wt% to 20 wt% of the total composition, preferably 3 wt% to 10 wt%, further improving the curing performance; in some embodiments of the present application, the cationic initiator includes iodonium salt and / or sulfonium salt photoinitiators, such as any one or more selected from diaryl iodonium sulfonate, triaryl sulfonium sulfonate, diaryl iodonium borate and triaryl sulfonium borate.

[0029] The cationic photoinitiator described above can be exemplified by the following structures: bis(dodecylphenyl)iodonium hexafluoroarsenate, bis(dodecylphenyl)iodonium hexafluoroantimonate, dialkylphenyl iodonium hexafluoroantimonate, diaryl iodonium perfluoroalkyl sulfonate, diaryl iodonium perfluorobutane sulfonate, diaryl iodonium perfluoroethane sulfonate, diaryl iodonium perfluorooctane sulfonate, diaryl iodonium trifluoromethane sulfonate, diaryl iodonium p-toluenesulfonate, diaryl iodonium dodecylbenzenesulfonate, diaryl iodonium benzenesulfonate, diaryl iodonium 3-nitrobenzenesulfonate, triaryl sulfonium perfluorobutane sulfonate, triaryl sulfonium perfluoroethane sulfonate, triaryl sulfonium perfluorooctane sulfonate, triaryl sulfonium trifluoromethane sulfonate, triaryl sulfonium p-toluenesulfonate, triaryl sulfonium dodecylbenzenesulfonate, triaryl sulfonium benzenesulfonate, triaryl sulfonium 3-nitrobenzenesulfonate, diaryl iodonium perhaloaryl borate, triaryl sulfonium perhaloaryl borate, one or more of which can be added to the composition, or one or more of which can be used simultaneously with other types of cationic photoinitiators.

[0030] The pigment in the cationic photopolymerization composition for ink of the present application serves as a colorant, without special requirements, which can be selected from the prior art. In some embodiments of the present application, the pigment is 0.5 wt% to 20 wt% of the total composition, such as 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%, 18 wt%, preferably 2 wt% to 15 wt%, which can better balance the color intensity and curing performance of the ink.

[0031] The pigments can be any color, such as black, blue, brown, cyan, green, white, violet, magenta, red, orange, and yellow, as well as special colors of their mixtures.

[0032] The pigments can be any one or more of organic pigments and / or inorganic pigments. For example, the organic pigments are selected from any one or more of naphthalene tetracene, 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 indigo pigments, root red pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, carbazole dioxazine violet pigments, alizarin lake pigments, phthalamide pigments, cochineal lake pigments, tetrachloroisoindolinone pigments, perinone pigments, anthraquinone pigments, and quinophthalone pigments; and the inorganic pigments are selected from any one or more 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 oxides, silicon oxides, carbon black pigments, metal sulfides, and metal chlorides.

[0033] In some embodiments of the present application, the above-mentioned composition further comprises a sensitizer for further improving the photosensitivity of the composition or meeting the light curing requirement under a long-wavelength light source, in particular, under a UV-LED light source. The content of the sensitizer in the above-mentioned cationic light curing composition for ink is 0.1 wt% to 15 wt%, preferably 3 wt% to 8 wt%.

[0034] The sensitizer can be selected from any one or more of thioxanthone compounds, xanthone compounds, acridine compounds, anthracene compounds, and coumarin compounds. In some preferred embodiments of the present application, the sensitizer is selected from any one or more of anthracene compounds and thioxanthone compounds, such as JRCure-1105 (ITX) and JRCure-1106 (DETX) produced by Tianjin Jiurixin Material, PSS303, PSS306, PSS506, PSS510, PSS513, PSS515, PSS402, PSS403, PSS603, etc. produced by Changzhou Qiangli Electronic New Material Co., Ltd.

[0035] In some embodiments of the present application, the total content of compound A-1 and compound A-2 in the above-mentioned cationic photocuring composition for ink is 50wt%-90wt% of the total content of the composition, such as 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, and the weight ratio of compound A-1 and compound A-2 in the composition is 8:5-2:5, such as 4:3, 1:1, 2:3, 1:2. The pattern effect after curing is better, and the probability of clogging the nozzle is further reduced, which is more suitable for inkjet printing of high-precision nozzles. Moreover, the researchers of the present application found that the higher the content of compound A-1 and compound A-2 in the cationic photocuring composition for ink, the more stable the viscosity of the composition, the better the clogging resistance of the ink, and the curing speed and pattern appearance are also relatively excellent.

[0036] According to the needs of the product application environment, the cationic photocuring composition for ink of the present application can also selectively add any one or more of the commonly used organic and / or inorganic auxiliaries in the art, such as leveling agents, dispersants, curing agents, surfactants, defoaming agents, storage enhancers. The specific components and amounts of the above-mentioned auxiliaries can refer to the prior art, which will not be described here.

[0037] The viscosity of the cationic photocuring composition for ink of the present application is not particularly limited. When the composition forms a coating layer by inkjet printing, the viscosity of the composition is usually preferably 50mPa·s or less, preferably 2-30mPa·s, more preferably 3-15mPa·s. The viscosity of the composition of the present application can be well controlled during storage, without the need to additionally add thickening agents or thinning agents.

[0038] The cationic photocuring composition for ink of the present application is not particularly limited in the form of the initiation energy source. It can undergo polymerization reaction and achieve rapid curing under energy radiation such as ultraviolet light, visible light, infrared light, electron beam, laser, etc. Illustratively, the initiation energy source can be active light such as ultraviolet light with a wavelength of 200-500nm, super-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 3 times wave laser, He-Cd laser, nitrogen laser, Xe-Cl excimer laser, Xe-F excimer laser, semiconductor excitation solid laser, i-ray, h-ray, g-ray, etc. The composition can also be cured by energy such as electron beam, alpha ray, beta ray, gamma ray, X-ray and neutron ray, and preferably mercury lamp ultraviolet lamp or UV-LED lamp with a wavelength range of 200-500nm, and the irradiation energy is preferably 20-1000mJ / cm 2 When using a long-wavelength energy source for curing, a sensitizer is preferably added to the composition to improve the photosensitivity of the composition.

[0039] The cationic photocuring composition of the present application is mixed with each component to obtain a radiation-curable inkjet ink. The preparation process can be carried out according to the methods of the prior art for radiation-curable compositions. Typically, the preparation process comprises: dispensing, pre-dispersing, milling, filtering (through a filter of a predetermined size to obtain a product having a desired particle size) under constant temperature and humidity and in the absence of a radiation source to obtain the inkjet ink.

[0040] According to another typical embodiment of the present application, there is provided the use of any of the above-described cationic photocuring compositions for ink.

[0041] The cationic photocuring composition of the present application used for ink can effectively improve the problem of clogging of the inkjet head of cationic polymerization-type ink, especially for high-precision inkjet heads. The pattern formed after curing of the cationic photocuring composition of the present application is clear, uniform, has strong adhesion and excellent appearance.

[0042] The thickness of the cured coating of the inkjet ink pattern formed by the cationic photocuring composition of the present application can be adjusted according to the prior art or according to the purpose of use. Preferably, the thickness of the inkjet ink pattern is 0.1-10 μm, and more preferably 0.5-5 μm. The coating formed is relatively uniform, and helps to control the cost. If the thickness of the inkjet ink coating is too small, the coating can not be uniformly formed, or it can be difficult to accurately print according to the design. If the thickness is too large, the coating can consume a large amount of printing ink, thereby increasing the cost and being not conducive to uniform application. The coating can be brittle and prone to delamination.

[0043] The cationic photocuring composition described above used as ink can be applied by any method known in the art, and is not particularly limited. In addition to inkjet printing, other known methods such as dip coating, air knife coating, curtain coating, roll coating, die coating, wire bar coating, etc. can also be used.

[0044] The cationic photocuring composition described above used as ink is not particularly limited in terms of the substrate to be used, such as a film, glass or plastic. The substrate can be optionally surface-treated, such as by corona treatment.

[0045] The beneficial effects of the present application will be further illustrated by the following examples and comparative examples.

[0046] 1. Preparation of ink

[0047] The components in the formulations of the examples and comparative examples in Tables 1 and 2 were stirred at a constant speed using a high-speed stirrer under yellow light for 1 hour, then ground using a sand mill, and then filtered through a 1 μm mesh screen to obtain ink compositions. The amounts shown in the examples and comparative examples in the tables are all in parts by weight.

[0048] Table 1

[0049]

[0050] Table 2

[0051]

[0052] The components shown by letters in the tables are as follows, where 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 cationic polymerizable compounds, C1 and C2 are cationic initiators, D1 and D2 are pigments, and E is a sensitizer.

[0053] A-11: (Synthesized in-house according to the synthesis method disclosed in JP 1995017958 A);

[0054] A-12: (Synthesized in-house according to the synthesis method disclosed in JP 1995017958 A);

[0055] A-21: (Synthesized in-house according to the synthesis method disclosed in US 3452054 A);

[0056] A-22: (Synthesized in-house according to the synthesis method disclosed in JP 3047800 B2);

[0057] A-13: (Synthesized in-house according to the synthesis method disclosed in JP 2000063522 A);

[0058] A-14: (Synthesized in-house according to the synthesis method disclosed in JP 1999315181 A);

[0059] A-15: (Synthesized in-house according to the synthesis method disclosed in US 3105838 A);

[0060] A-16: (Trade name: THM209-1);

[0061] A-23: 4,4-bis[(3-ethyl-3oxetanyl)methoxymethyl]biphenyl (cas: 358365-48-7);

[0062] A-24: 3-hydroxy-3-hydroxymethyloxetane (cas: 16563-93-2);

[0063] B1: poly[(2-oxiranylmethyl)-1,2-cyclohexanediol] 2-ethyl-2-(hydroxymethyl)-1,3- propanediol ether (3:1) (trade name: TTA3150);

[0064] B2: 4,4-bis[(3-ethyl-3oxetanyl)methoxymethyl]biphenyl (Changzhou Qiangli Electronic New Material Co., Ltd.);

[0065] C1: bis(dodecylphenyl) iodonium hexafluoroantimonate (Changzhou Qiangli Electronic New Material Co., Ltd.);

[0066] C2: triphenylsulfonium hexafluorophosphate (Changzhou Qiangli Electronic New Material Co., Ltd.);

[0067] D1: inorganic carbon black (Clariant Chemicals (China) Co., Ltd.);

[0068] D2: titanium white (Shanghai Shucan Industry Co., Ltd.);

[0069] E: 2-ethylanthracene-9,10-di(3-cyclohexylpropanoate) (trade name: PSS506).

[0070] 2. Test of ink curing and drying speed

[0071] The ink to be tested of each example and comparative example was printed using a Sun Chemical solventless inkjet printer (model: A380) to which a LED lamp with a wavelength of 395 nm was added as a radiation light source. The ink to be tested was transferred onto a PET film (ordinary industrial film FP2 of Lucky Group) by the inkjet printer, the printing thickness was set to 5 μm, and the power of the LED light source was 20 w / cm 2 .

[0072] After the illumination, the surface curing was evaluated according to the touch method in the paint film drying time test standard GB / T 1728-1979, i.e. the surface was confirmed to be dry by touching the coating with a finger, and the surface was smooth, not sticky, and no fingerprints were left after pressing. The drying speed was represented by the maximum linear speed to achieve the surface drying effect, with the unit of m / min, and the test results are shown in Table 3. The curing and drying speed can reflect the activity of the composition, and the greater the curing and drying speed, the faster the curing speed and the higher the activity of the composition.

[0073] 3. Evaluation of ink cured coating adhesion and print appearance

[0074] The line speed on the inkjet printer (Inside) was set to 220 m / min and 150 m / min, respectively, the PET film (JPC-P1-125) was used as the substrate, the printing thickness was set to 5 μm, and the irradiation energy of the 395 nm LED light source was 20 mJ / cm 2 After exposure, the samples were placed for 24 h, and the basic properties of the cured coating adhesion, print appearance, etc. were evaluated, and the evaluation results are shown in Table 3.

[0075] (1) Coating adhesion test

[0076] According to GB / T9286-1998 Scratch Test for Paint and Varnish Film, a cross-hatch method was used, and a QFH paint film cross-hatch instrument was used to test the adhesion on the substrate. The specific implementation method is as follows:

[0077] A knife in accordance with GB / T9286-1998 Scratch Test for Paint and Varnish Film was used to cut the surface of the coating, ensuring that each cut penetrated to the substrate surface. A soft brush was used to clean the surface of the coating, and then an adhesive tape was applied to the coating to ensure full contact between the tape and the coating. Finally, the tape was peeled off the surface of the coating, and the results were evaluated based on the following criteria. The specific evaluation results are shown in Table 3.

[0078] 0: The cutting edge is completely smooth, and no grid is detached.

[0079] 1: There is a little coating detachment at the intersection of the cuts, but the affected cross-cut area is not significantly greater than 5%.

[0080] 2: There is coating detachment at the intersection of the cuts and / or along the cutting edge, and the affected cross-cut area is significantly greater than 5% but not significantly greater than 15%.

[0081] 3: The coating partially or completely detaches in large pieces along the cutting edge and / or partially or completely detaches at different parts of the grid, and the affected cross-cut area is significantly greater than 15% but not significantly greater than 35%.

[0082] 4: The coating detaches in large pieces along the cutting edge and / or partially or completely detaches at some grids, and the affected cross-cut area is significantly greater than 35% but not significantly greater than 65%.

[0083] 5: The degree of peeling exceeds level 4.

[0084] (2) Print appearance evaluation

[0085] According to GB / T 7707-2008 inkjet decoration printing standard, the inkjet printing with a depth of 10-18 μm, the printed matter after 24 h is placed under the observation light source in accordance with CY / T 3, and is identified by visual inspection. The printed matter is neat, without obvious ink stains, defects, and knife silk; the text printing is clear and complete, without defects and deformation, and the less than 7.5P characters do not affect the reading; the solid printing trace edge is smooth, the ink color is uniform, and there is no obvious water streak; the printing level transition is smooth, without obvious step jump; the screen dots are clear and uniform, without obvious deformation and defects; the printing color phase meets the requirements of the printed sample, and is considered to be qualified; otherwise, any one item is not ideal and is recorded as unqualified.

[0086] (3) Clogging resistance evaluation

[0087] The nozzles used in the experiment are: nozzle A, model KJ4A-0300 (4PL, 112.35 mm); nozzle B, model G5I (3.5PL, 10-15 mm).

[0088] The use of the ink of each example and the comparative example is observed under the operation and the pre-operation of the two nozzles, and the evaluation method is as follows:

[0089] ① Under the operation:

[0090] According to the above experimental formula, the test pattern of a quadrilateral of 3x3 cm is recorded on the PET film (JPC-P1-125) along the longitudinal and transverse directions, and each test pattern is recorded with a 3 cm interval, and after 2 h of continuous recording, the basic situation of nozzle column nozzle A (1328 holes of KJ4A-0300) and nozzle B (1280 holes of G5I) is checked, and the criteria are as follows:

[0091] A: no non-ejection nozzle;

[0092] B: non-ejection nozzle is 2% or less;

[0093] C: non-ejection nozzle is more than 2% but less than 5%;

[0094] D: non-ejection nozzle is more than 5%.

[0095] ② Under the pre-operation:

[0096] According to the above experimental formula, the ink of each example and the comparative example is filled into different models of the nozzle, the viscosity change of the composition placed for 8 h and 48 h is recorded, the composition is placed for 48 h, and after 2 h of continuous recording, the situation of nozzles A and B is observed, and the criteria are as follows:

[0097] A: no non-ejection nozzle;

[0098] B: non-ejection nozzle is 2% or less;

[0099] C: More than 2% but less than 5% of the nozzles do not spray.

[0100] D: More than 5% of the nozzles do not spray.

[0101] Table 3

[0102]

[0103]

[0104] From the performance evaluation results in Table 3, it can be seen that the cationic photocuring composition described in the present application has excellent curing performance, and the viscosity is basically not affected after long-term storage. It does not clog the nozzle under continuous operation or intermittent operation, and the effect is obvious especially in the application of high-precision nozzles, and has strong application prospect.

[0105] From the above description, it can be seen that the above-described embodiments of the present application achieve the following technical effects: the cationic photocuring composition for ink of the present application applied to ink can effectively improve the problem that cationic polymerization type ink is easy to clog the nozzle, especially for high-precision nozzles, the effect is particularly remarkable, and the pattern formed after the cationic photocuring composition for ink of the present application is cured is clear, uniform, has strong adhesion, and has excellent appearance performance.

[0106] The above is only a preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A cationic photocurable composition for inks, characterized in that, 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; The structural formula of the compound A-1 is R1 represents a methyl group or an ethyl group; the compound A-2 is a polymerizable monomer without vinyl group, with a molecular weight less than 300 and the molecular weight of oxygen in the molecule accounts for 12-30% of the molecular weight of the compound; the content of the compound A-1 and the compound A-2 accounts for 50wt%-90wt% of the total amount of the composition; the weight ratio of the compound A-1 and the compound A-2 is 1:5-8:1; The compound A-2 includes any one or more selected from the group consisting of the following structures: , , , , , , , , , , , , , , ; the cationic polymerizable compound further comprises a third cationic polymerizable compound, the content of the third cationic polymerizable compound is 0.1wt%-40wt% of the total amount of the composition; the third cationic polymerizable compound comprises any one or more of alicyclic epoxy compound, oxetane compound and vinyl ether compound; the addition amount of the cationic initiator is 3wt%-10wt% of the total amount of the composition; the cationic initiator comprises iodonium salt and / or sulfonium salt photoinitiator; the pigment is 2wt%-15wt% of the total amount of the composition; the composition further comprises a sensitizer, the content of the sensitizer in the composition is 3wt%-8wt%, and the sensitizer is selected from any one or more of anthracene compound and thioxanthone compound.

2. The composition of claim 1, wherein, The content of the third cationic polymerizable compound is 5wt%-30wt% of the total amount of the composition.

3. The composition of claim 1, wherein, The cationic initiator is selected from any one or more of diaryliodonium salt of sulfonic acid, triarylsulfonium salt of sulfonic acid, diaryliodonium salt of boric acid and triarylsulfonium salt of boric acid.

4. The composition of claim 1, wherein, The pigment is organic pigment and / or inorganic pigment.

5. The composition of claim 4, wherein, The organic pigment is selected from any one or more of perylene, phthalocyanine dye and azo pigment; The inorganic pigment is selected from any one or more of titanium oxide, iron oxide, aluminum oxide, silicon oxide, carbon black pigment, metal sulfide and metal chloride.

6. The composition according to any one of claims 1 to 5, characterized in that, The use amount ratio of the compound A-1 and the compound A-2 is 2:5-8:

5.

7. The composition according to any one of claims 1 to 5, characterized in that, The composition further comprises an auxiliary agent, the auxiliary agent comprises any one or more of leveling agent, dispersant, curing agent, surfactant, defoaming agent and storage enhancer.

8. The composition according to any one of claims 1 to 5, characterized in that, The viscosity of the composition is less than 50mPa·s.

9. The composition of claim 8, wherein, The viscosity of the composition is 2-30mPa·s.

10. The composition according to any one of claims 1-9 is used in ink.

11. Use according to claim 10, characterized in that, The substrate used in the ink comprises any one of film, glass and plastic.

12. Use according to claim 11, characterized in that, The spray thickness of the composition is 0.1-10μm.

13. Use according to claim 12, characterized in that, The spray thickness of the composition is 0.5-5μm.

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