Active energy ray-curable yellow ink and image recording method

Abstract

An active energy ray-curable yellow ink and an application thereof, the active energy ray-curable yellow ink comprising: at least one yellow pigment selected from the group consisting of PY110 and PY184; a polymerizable monomer A that contains a nitrogen atom and has a glass transition temperature of more than 60 DEG C when used as a homopolymer; and a polymerizable monomer B which has a glass transition temperature of 60 DEG C or less when used as a homopolymer and is a monofunctional polymerizable monomer, the total content of the polymerizable monomer A and the polymerizable monomer B being 50 mass% or more with respect to the total amount of the active energy ray-curable yellow ink, and Mp / D being 1.0-2.0.

Description

Technical Field

[0001] This invention relates to an active energy X-ray curable yellow ink and an image recording method. Background Technology

[0002] In recent years, research has been conducted on yellow inks that are cured by active energy rays.

[0003] For example, International Publication No. 2008 / 038508 states that in a yellow ink containing pigment, reactive monomer and / or reactive oligomer and photopolymerization initiator, the pigment is CI Pigment Yellow 184 and / or CI Pigment Yellow 42.

[0004] Furthermore, Japanese Patent Application Publication No. 2017-149811 discloses a radiation-curable inkjet composition containing a specific monomer A, a urethane (meth) acrylate oligomer with three or fewer functions, and an N-vinyl compound. Summary of the Invention

[0005] The technical problem to be solved by the invention For yellow images recorded using reactive energy radiation-cured yellow inks, it is sometimes necessary to improve weather resistance over long periods (i.e., long-term weather resistance) while maintaining the chromaticity of the yellow pigment. Weather resistance generally refers to the property of not easily deteriorating under outdoor conditions. In particular, long-term weather resistance requires resistance to fading (the property of not easily fading), resistance to cracking (the property of not easily cracking on the image surface), and resistance to adhesion (the property of not easily sticking to the image surface). Further improvements in long-term weather resistance are required compared to previous weather resistance methods.

[0006] One embodiment of the present invention aims to provide an active energy X-ray curable yellow ink and an image recording method that can record yellow images with excellent fading resistance, crack resistance and adhesion resistance after a long period of time while maintaining the chromogenic properties of yellow pigment.

[0007] means for solving technical problems The specific methods used to solve the problem include the following approaches.

[0008] <1> An active energy ray-curable yellow ink, comprising: At least one yellow pigment, selected from the group consisting of Pigment Yellow 110 and Pigment Yellow 184; Polymerizable monomer A, as a homopolymer, has a glass transition temperature exceeding 60°C and contains nitrogen atoms; and Polymerizable monomer B, when used as a homopolymer, has a glass transition temperature below 60°C and is a monofunctional polymerizable monomer. The total content of polymerizable monomer A and polymerizable monomer B relative to the total amount of active energy ray-curable yellow ink is 50% by mass or more. When the content of yellow pigment relative to the total amount of active energy ray-curable yellow ink is set as Mp and the specific gravity of yellow pigment is set as D, Mp / D is 1.0 to 2.0.

[0009] <2> According to the active energy ray curable yellow ink described in <1>, wherein... The content of polymeric monomer A is 10% to 30% by mass relative to the total amount of active energy ray curable yellow ink.

[0010] <3> According to the active energy ray curable yellow ink described in <1> or <2>, wherein, The weighted average of the glass transition temperatures of all polymerizable monomers contained in the active energy X-ray curable yellow ink, when used as homopolymers, is 20℃~70℃.

[0011] <4> The active energy ray curable yellow ink according to any one of <1> to <3>, wherein, The weighted average of the glass transition temperatures of all polymerizable monomers contained in the active energy X-ray curable yellow ink, when used as homopolymers, is 20℃~50℃.

[0012] <5> The active energy ray curable yellow ink according to any one of <1> to <4>, wherein, The mass ratio of polymeric monomer A to polymeric monomer B is 0.1 to 0.5.

[0013] <6> The active energy ray-curable yellow ink according to any one of <1> to <5>, wherein, When polymerizable monomer B is used as a homopolymer, the glass transition temperature is below 10°C.

[0014] <7> The active energy ray curable yellow ink according to any one of <1> to <6> further comprises a resin with a glass transition temperature of 40°C to 110°C.

[0015] <8> According to the active energy ray curable yellow ink described in <7>, wherein... Resins with a glass transition temperature of 40℃~110℃ are (meth)acrylic resins with a glass transition temperature of 40℃~110℃.

[0016] <9> According to the active energy ray curable yellow ink described in <8>, wherein... The amount of (meth)acrylic resin with a glass transition temperature of 40℃ to 110℃ is 0.2% to 2.0% by mass relative to the total amount of active energy X-ray curable yellow ink.

[0017] <10> The active energy ray-curable yellow ink according to any one of <1> to <9>, wherein, The yellow pigment is Pigment Yellow 184.

[0018] <11> An image recording method includes the following steps: Applying any one of <1> to <10> of an active energy ray-curable yellow ink to a substrate by inkjet recording; and The active energy radiation-curable yellow ink applied to the substrate is irradiated with active energy radiation.

[0019] Invention Effects According to one embodiment of the present invention, an active energy X-ray curable yellow ink and an image recording method are provided, which can record yellow images with excellent fading resistance, crack resistance and adhesion resistance after a long period of time while maintaining the color development properties of yellow pigment. Detailed Implementation

[0020] The present invention will now be described in detail.

[0021] The following description of the constituent elements is sometimes based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0022] Furthermore, in this invention, the "~" sign indicating a numerical range is used to encompass the values ​​recorded before and after it as a lower limit and an upper limit.

[0023] In the numerical ranges described in this specification, the upper or lower limit of a numerical range can be replaced with the upper or lower limit of other numerical ranges described in different stages. Furthermore, in the numerical ranges described in this invention, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the embodiments.

[0024] In this invention, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of the multiple components present in the composition.

[0025] In this invention, either or both acrylic acid and methacrylic acid are sometimes referred to as "(meth)acrylic acid". For example, "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0026] In this invention, acrylates and methacrylates, or either of them, are sometimes referred to as "(meth)acrylates".

[0027] In this invention, the term "process" includes not only independent processes, but also processes that can achieve their intended purpose, even if they cannot be clearly distinguished from other processes.

[0028] In this invention, compounds that are not explicitly described as substituted or unsubstituted may have any substituents without impairing the effects of this invention.

[0029] Furthermore, in this invention, the combination of preferred methods is a more preferred method.

[0030] In this invention, "pigment yellow" refers to CI (color index) pigment yellow.

[0031] In this invention, "pigment yellow" is sometimes referred to as "PY".

[0032] The active energy ray curable yellow ink (hereinafter also simply referred to as "ink") of the present invention comprises: at least one yellow pigment selected from the group consisting of pigment yellow 110 and pigment yellow 184; polymerizable monomer A, which has a glass transition temperature of more than 60°C when used as a homopolymer and contains nitrogen atoms; and polymerizable monomer B, which has a glass transition temperature of less than 60°C when used as a homopolymer and is a monofunctional polymerizable monomer. The total content of polymerizable monomer A and polymerizable monomer B relative to the total amount of ink is 50% by mass or more, and when the content of yellow pigment relative to the total amount of ink is set as Mp and the specific gravity of yellow pigment is set as D, Mp / D is 1.0 to 2.0.

[0033] The ink according to the present invention can record yellow images with excellent long-term weather resistance (resistance to fading, cracking and adhesion) while maintaining the color development properties of the yellow pigment.

[0034] Hereinafter, these terms will be referred to as "fading resistance, crack resistance, and adhesion resistance," but all refer to the properties of fading resistance, crack resistance, and adhesion resistance as long-term weather resistance.

[0035] The ink of the present invention contains at least one selected from the group consisting of Pigment Yellow 110 and Pigment Yellow 184 as a yellow pigment, thus exhibiting excellent color development properties.

[0036] In the ink of this invention, a polymerizable monomer A containing nitrogen atoms and having a glass transition temperature exceeding 60°C when used as a homopolymer contributes to improved anti-blocking properties. This is believed to be because the presence of polymerizable monomer A results in excellent surface curing properties of the formed ink film. Exposure to outdoor light or similar sources causes the components in the ink film to decompose, easily leading to a viscous feel on the surface of the ink film; however, if the ink film exhibits excellent surface curing properties, this viscous feel is suppressed.

[0037] Furthermore, in the ink of the present invention, polymerizable monomer B, which has a glass transition temperature of 60°C or less when used as a homopolymer and is a monofunctional polymerizable monomer, helps to improve crack resistance. This is believed to be because the presence of polymerizable monomer B imparts flexibility to the formed ink film.

[0038] The total content of polymeric monomers A and B, which have the effects described above, is more than 50% by mass relative to the total amount of ink, thus exhibiting excellent resistance to tack and cracking.

[0039] Furthermore, when the content of yellow pigment relative to the total amount of ink is set as Mp, and the specific gravity of yellow pigment is set as D, the Mp / D ratio is 1.0 to 2.0, resulting in excellent resistance to clogging and cracking. This is believed to be because, if Mp / D is 1.0 to 2.0, the yellow pigment is appropriately concentrated on the surface of the ink film.

[0040] In contrast, International Publication No. 2008 / 038508 does not contain any description of a combination of polymeric monomer A and polymeric monomer B. Furthermore, Japanese Patent Application Publication No. 2017-149811 does not specify that the total content of polymeric monomer A and polymeric monomer B is 50% by mass or more.

[0041] [Active Energy X-ray Curing Type Yellow Ink] The ink of the present invention is an active energy radiation-curable yellow ink. That is, the ink of the present invention is cured by irradiation with active energy radiation. Examples of active energy radiation include gamma rays, beta rays, electron beams, ultraviolet light, and visible light. Ultraviolet light is preferred among these active energy rays. The ink of the present invention is preferably an ultraviolet-curable yellow ink.

[0042] The components contained in the ink of the present invention will be described below.

[0043] <Yellow Pigment> The ink of the present invention comprises at least one yellow pigment selected from the group consisting of Pigment Yellow 110 (PY110) and Pigment Yellow 184 (PY184) (hereinafter also referred to as "specific yellow pigment"). PY110 and PY184 have excellent color development properties.

[0044] PY184 is a yellow inorganic pigment formed from bismuth vanadate. PY184 is a commercially available product.

[0045] Commercially available products include, for example, Sicopal L1100, Sicopal L1110, Sicopal L1120, Sicopal L1600 (all manufactured by BASF), Lysopac Yellow 6601B, Lysopac Yellow 6611B, Lysopac Yellow 6615B, and Lysopac Yellow 6616B (all manufactured by Cappelle).

[0046] PY110 is a yellow pigment formed from isoindolinone. PY110 is available commercially.

[0047] As a commercially available product, for example, Irgazin Yellow L 2040 (manufactured by DIC Corporation) can be cited.

[0048] The smaller the average particle size of the pigment, the better its color development. The volume average particle size of a specific yellow pigment is preferably 0.01 μm to 0.4 μm, more preferably 0.02 μm to 0.3 μm.

[0049] In this invention, the volume average particle size is represented by the value measured by a laser diffraction / scattering particle size analyzer.

[0050] As a measuring device, an example is the particle size distribution measuring device "Microtrac MT-3300II" (manufactured by Nikkiso Co., Ltd.).

[0051] From the viewpoint of image density, the content of a specific yellow pigment is preferably 1% to 15% by mass, more preferably 2% to 10% by mass, relative to the total amount of ink.

[0052] In addition, the content of a specific yellow pigment was adjusted to meet the Mp / D range described later.

[0053] (Mp / D) In the ink of the present invention, when the content of a specific yellow pigment relative to the total amount of ink is set as Mp and the specific gravity of the specific yellow pigment is set as D, Mp / D is 1.0 to 2.0.

[0054] The specific gravity of the yellow pigment was determined using the Ultrapyc5000 series true density measuring device manufactured by Anton Paar Japan KK.

[0055] In the case where the ink of the present invention contains both PY110 and PY184, the specific yellow pigment is represented by a weighted average.

[0056] If Mp / D is above 1.0, the yellow pigment is appropriately present on the surface of the ink film, thereby improving the resistance to tack.

[0057] If Mp / D is below 2.0, the yellow pigment will not be present excessively on the surface of the ink film, thus improving crack resistance.

[0058] From the perspective of further improving adhesion resistance and crack resistance, Mp / D is preferably 1.2 to 1.7.

[0059] PY184 has a higher specific gravity than PY110. Therefore, when using PY184 as a yellow pigment, its content in the ink can be increased to achieve an Mp / D ratio of 1.0 to 2.0 compared to using PY110.

[0060] From the perspective of balancing color development, crack resistance, and adhesion resistance, PY184 is the preferred yellow pigment.

[0061] The ink of the present invention may contain colorants other than a specific yellow pigment. However, in order to maintain the color of the yellow ink, it is preferable not to contain colorants other than a specific yellow pigment.

[0062] -polymerizable monomer A- The ink of the present invention contains a homopolymer with a glass transition temperature exceeding 60°C and contains a polymerizable monomer A containing nitrogen atoms. By including polymerizable monomer A in the ink, the resistance to tack-blocking is improved.

[0063] Polymerizable monomer A is a monomer containing a polymerizable group. The polymerizable group is preferably an olefinic unsaturated group, more preferably vinyl, allyl, or (meth)acryloyl, and even more preferably (meth)acryloyl.

[0064] The molecular weight of polymerizable monomer A is preferably 1000 or less, more preferably 500 or less, and even more preferably 400 or less. The lower limit of the molecular weight is, for example, 100.

[0065] In compounds with a molecular weight of less than 1000, the molecular weight is calculated based on the types and numbers of atoms that make up the compound.

[0066] From the viewpoint of further improving resistance to adhesion, the glass transition temperature of polymerizable monomer A is preferably 70°C or higher, more preferably 80°C or higher. An upper limit for the glass transition temperature is, for example, 180°C.

[0067] The glass transition temperature of polymerizable monomers as homopolymers was determined by the following method.

[0068] First, homopolymers with a weight average molecular weight of 10,000 to 20,000 are prepared using polymerizable monomers. The glass transition temperature of the prepared homopolymers is determined according to the method described in JIS K 7121:2012.

[0069] In this invention, the glass transition temperature is determined using a differential scanning calorimeter, for example, using the product name "DSC-60" manufactured by SHIMADZUCORPORATION.

[0070] In this invention, the weight-average molecular weight was determined using gel permeation chromatography (GPC). For example, an HLC-8220 GPC (manufactured by TOSOH CORPORATION) was used as the GPC column, with three TSKgel Super Multipore HZ-H (manufactured by TOSOH CORPORATION, 4.6 mm ID × 15 cm) columns used as the eluent, and THF (tetrahydrofuran) as the eluent. The conditions were set as follows: sample concentration 0.45% by mass, flow rate 0.35 ml / min, sample injection volume 10 μL, measurement temperature 40°C, and detection using a differential refractive index (RI) detector. Calibration curves were prepared using eight samples manufactured by Tosoh Corporation under the product name "TSK Standard Polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene" as standard samples.

[0071] Furthermore, the glass transition temperature of the homopolymer varies depending on its weight-average molecular weight, but the variation is negligible when the weight-average molecular weight is between 10,000 and 20,000.

[0072] The polymerizable monomer A may contain only one polymerizable group or more than two polymerizable groups. From the viewpoint of crack resistance, it is preferable to have only one polymerizable group. That is, polymerizable monomer A is preferably a monofunctional polymerizable monomer.

[0073] Examples of polymerizable monomers A include N-vinylcaprolactam, acrylamide, vinylmethyloxazolidinone, N-vinylpyrrolidone, N-isopropylacrylamide, and N,N-dimethylacrylamide.

[0074] The content of polymeric monomer A relative to the total mass of the ink is preferably 1% to 60% by mass, more preferably 5% to 40% by mass, and even more preferably 10% to 30% by mass.

[0075] If the content of polymerizable monomer A is 1% by mass or more, the ink film exhibits excellent surface curing properties and resistance to adhesion.

[0076] If the content of polymerizable monomer A is below 60% by mass, the ink film will not become too hard and will have excellent crack resistance.

[0077] -polymerizable monomer B- The ink of the present invention contains polymerizable monomer B, which has a glass transition temperature of 60°C or less when used as a homopolymer and is a monofunctional polymerizable monomer. By including polymerizable monomer B in the ink, crack resistance is improved.

[0078] Polymerizable monomer B is a monomer containing one polymerizable group (monofunctional polymerizable monomer). The polymerizable group is preferably an olefinic unsaturated group, more preferably vinyl, allyl, or (meth)acryloyl, and even more preferably (meth)acryloyl.

[0079] The molecular weight of polymerizable monomer B is preferably 1000 or less, more preferably 500 or less, and even more preferably 400 or less. The lower limit of the molecular weight is, for example, 100.

[0080] From the viewpoint of further improving adhesion resistance, the glass transition temperature of polymerizable monomer B is preferably below 40°C, more preferably below 10°C. For example, the lower limit of the glass transition temperature is -60°C.

[0081] Examples of polymerizable monomers B include cyclic trimethylolpropane acetal acrylate (CTFA), cyclohexyl acrylate (CHA), tetrahydrofurfuryl acrylate (THFA), (2-methyl-2-ethyl-1,3-dioxolane-4-yl)methacrylate (MEDOL-10) and benzyl acrylate (BzA).

[0082] The content of polymerizable monomer B relative to the total mass of the ink is preferably 10% to 90% by mass, more preferably 20% to 80% by mass, and even more preferably 30% to 70% by mass.

[0083] If the content of polymerizable monomer B is 10% by mass or more, the ink film will have excellent flexibility and excellent crack resistance.

[0084] If the content of polymerizable monomer B is below 90% by mass, the surface curing properties are maintained and the adhesion resistance is excellent.

[0085] The total content of polymeric monomer A and polymeric monomer B relative to the total amount of ink is 50% by mass or more, preferably 60% by mass or more. The upper limit of the total content is not particularly limited, but from the viewpoint of balance with other components, 80% by mass is preferred.

[0086] In the ink of the present invention, the total content of polymerizable monomer A and polymerizable monomer B is more than 50% by mass, thus achieving both crack resistance and adhesion resistance.

[0087] From the viewpoint of further improving crack resistance and adhesion resistance, the mass ratio of the content of polymeric monomer A to the content of polymeric monomer B is preferably 0.1 to 0.5, more preferably 0.2 to 0.4.

[0088] <Other polymerizable monomers> The ink of the present invention may contain other polymerizable monomers besides polymerizable monomer A and polymerizable monomer B.

[0089] Other polymerizable monomers are preferably free radical polymerizable monomers, and more preferably olefinic unsaturated monomers.

[0090] Other polymerizable monomers include, for example, (meth)acrylate compounds, (meth)acrylamide compounds, vinyl ether compounds, allyl compounds, N-vinyl compounds, unsaturated carboxylic acids, etc.

[0091] Other polymerizable monomers may include free radical polymerizable monomers described in Japanese Patent Application Publication No. 2009-221414, free radical polymerizable compounds described in Japanese Patent Application Publication No. 2009-209289, and olefinic unsaturated compounds described in Japanese Patent Application Publication No. 2009-191183.

[0092] Other free radical polymerizable monomers are preferably (meth)acrylate compounds or vinyl ether compounds.

[0093] As other polymerizable monomers, they can be monofunctional polymerizable monomers or polymerizable monomers with two or more functions.

[0094] The ink of the present invention preferably contains polymerizable monomers with two or more functions as other polymerizable monomers, more preferably contains free radical polymerizable monomers with two or three functions, and even more preferably contains free radical polymerizable monomers with two functions.

[0095] From the viewpoint of further improving crack resistance and adhesion resistance, the weighted average of the glass transition temperatures when all polymerizable monomers contained in the ink are respectively set as homopolymers is preferably 20°C to 70°C, more preferably 20°C to 50°C.

[0096] The weighted average of the glass transition temperatures is calculated using the following formula. Where T i The glass transition temperature (C) represents the temperature at which the i-th polymerizable monomer in the ink is a homopolymer. i This represents the content (mass%) of the i-th polymerizable monomer relative to the total amount of ink.

[0097] Weighted average of glass transition temperatures = ΣT i C i / ΣC i By adjusting the glass transition temperature and content of polymerizable monomers A, B, and others, the weighted average glass transition temperature can be adjusted to fall within the aforementioned range.

[0098] <Resin> The ink of the present invention preferably contains at least one resin. The resin described herein does not have the function of dispersing yellow pigments and is different from the dispersants described later.

[0099] It is believed that if the ink contains resin, the decomposition of the cross-linked structure formed by polymeric monomers A and B is inhibited through the resin present on the surface of the ink film. Therefore, if the ink contains resin, the anti-blocking property is improved.

[0100] The weight-average molecular weight of the resin is not particularly limited, but from the viewpoint of further improving crack resistance and adhesion resistance, it is preferably 1000 or more, more preferably 3000 or more, and even more preferably 5000 or more. On the other hand, from the viewpoint of ink sprayability and storage stability, the weight-average molecular weight of the resin is preferably 80000 or less, more preferably 60000 or less, and even more preferably 40000 or less.

[0101] The method for determining weight-average molecular weight is as described above.

[0102] Examples of resins include vinyl resins, (meth)acrylic resins, urethane resins, and polyester resins.

[0103] From the perspective of crack resistance, the resin is preferably (meth)acrylic resin.

[0104] In this invention, (meth)acrylic resin refers to a resin comprising a constituent unit derived from a compound having a (meth)acryloyl group (e.g., (meth)acrylate).

[0105] From the viewpoint of improving crack resistance and adhesion resistance, the glass transition temperature of the resin is preferably 30℃~120℃, more preferably 40℃~110℃.

[0106] The method for determining the glass transition temperature is as described above.

[0107] In particular, from the viewpoint of further improving crack resistance and adhesion resistance, the ink of the present invention preferably contains a resin with a glass transition temperature of 40°C to 110°C (hereinafter also referred to as "specific resin").

[0108] From the viewpoint of crack resistance, a particular resin is preferably a (meth)acrylic resin with a glass transition temperature of 40°C to 110°C.

[0109] From the viewpoint of further improving crack resistance and adhesion resistance, the glass transition temperature of a specific resin is preferably 50°C to 80°C.

[0110] The content of a specific resin relative to the total amount of ink is preferably 0.2% to 2.0% by mass, more preferably 0.5% to 1.5% by mass.

[0111] If the content of a specific resin is 0.2% by mass or more, the anti-blocking properties are excellent.

[0112] If the content of a specific resin is less than 2.0% by mass, the spraying performance is excellent.

[0113] <Dispersant> In order to disperse a specific yellow pigment in the ink, the ink of the present invention preferably contains a dispersant.

[0114] As a dispersant, known dispersants can be used.

[0115] Dispersants can be commercially available products. Examples of commercially available products include: DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-110, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DI SPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (the above, manufactured by BYK-Chemie); and SOLSPERSE3000, SOLSPERSE5000, SOLSPERSE9000, SOLSPERSE12000, SOLSPERSE13240, SOLSPERSE13940, SOLSPERSE17000, SOLSPERSE22000, SOLSPERSE24000, SOLSPERSE26000, SOLSPERSE28000, SOLSPERSE32000, SOLSPERSE36000, SOLSPERSE39000, SOLSPERSE41000, SOLSPERSE71000 (all manufactured by Lubrizol).

[0116] As a dispersing device for dispersing pigments, known dispersing devices can be used, such as ball mills, sand mills, bead mills, roller mills, spray mills, paint mixers, grinders, ultrasonic dispersers, and dispersers.

[0117] From the viewpoint of dispersion stability, the mass ratio of the dispersant content to the content of the specific yellow pigment is preferably 0.05 to 1.0, more preferably 0.1 to 0.5.

[0118] <Polymerization Initiator> The ink of the present invention preferably contains at least one polymerization initiator.

[0119] As a polymerization initiator, a photoradical polymerization initiator that absorbs light and generates free radicals as polymerization initiation species is preferred.

[0120] Examples of polymerization initiators include alkyl phenyl ketone compounds, acylphosphine compounds, aromatic ononium salt compounds, organic peroxides, thio compounds, hexaaryl biimidazole compounds, ketooxime ester compounds, borate compounds, azadinium compounds, metallocene compounds, active ester compounds, compounds with carbon-halogen bonds, and alkylamine compounds.

[0121] The polymerization initiator is preferably selected from at least one of the groups consisting of alkyl phenyl ketone compounds and acylphosphine compounds, and more preferably a combination of alkyl phenyl ketone compounds and acylphosphine compounds.

[0122] Examples of alkyl phenyl ketone compounds include, for example, α-hydroxyalkyl phenyl ketone compounds, α-aminoalkyl phenyl ketone compounds, and benzyl ketal alkyl phenyl ketone compounds.

[0123] Examples of α-hydroxyalkylphenyl ketone compounds include, for example, 2,2'-dihydroxy-2,2'-dimethyl-1,1'-[methylenebis(4,1-phenylene)]bis(propane-1-one), 1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-2-hydroxy-1-propanone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, and 1-hydroxycyclohexylphenyl ketone.

[0124] Examples of α-aminoalkyl phenyl ketone compounds include, for example, 2-methyl-1-phenyl-2-morpholinylprop-1-one, 2-methyl-1-[4-(hexyl)phenyl]-2-morpholinylprop-1-one, 2-ethyl-2-dimethylamino-1-(4-morpholinylphenyl)but-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)but-1-one, and 2-dimethylamino-2-(4-)but-1-one. (methylbenzyl)-1-(4-morpholino-4-yl-phenyl)-but-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinoprop-1-one, 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)-but-1-one and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-but-1-one.

[0125] Examples of benzyl ketal alkyl phenone compounds include, for example, 2,2-dimethoxy-2-phenylacetophenone.

[0126] Alkyl phenyl ketone compounds are commercially available. Examples of commercially available compounds include, for instance, Omnirad 651, Omnirad 184, Omnirad 1173, Omnirad 2959, Omnirad 127, Omnirad 907, Omnirad 369, Omnirad 369E, and Omnirad 379 (manufactured by IGM Resins BV).

[0127] Examples of acylphosphine oxide compounds include monoacylphosphine oxide compounds and diacylphosphine oxide compounds, with diacylphosphine oxide compounds being preferred.

[0128] Examples of monoacylphosphine oxide compounds include isobutyryl diphenylphosphine oxide, 2-ethylhexanoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, o-toluyl diphenylphosphine oxide, p-tert-butylbenzoyl diphenylphosphine oxide, 3-pyridylcarbonyl diphenylphosphine oxide, acryloyl diphenylphosphine oxide, benzoyl diphenylphosphine oxide, and neopentyl phenylphosphine. Vinyl ester, adipyl bis(diphenylphosphine oxide), neopentyl diphenylphosphine oxide, p-toluyl diphenylphosphine oxide, 4-(tert-butyl)benzoyl diphenylphosphine oxide, terephthalyl bis(diphenylphosphine oxide), 2-methylbenzoyl diphenylphosphine oxide, neodecanoyl diphenylphosphine oxide, 2-methyl-2-ethylhexanoyl diphenylphosphine oxide, 1-methyl-cyclohexanoyl diphenylphosphine oxide, methyl neopentyl phenylphosphine and isopropyl neopentyl phenylphosphine.

[0129] Examples of diacylphosphine oxide compounds include, for example, bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-ethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, and bis(2,6-dichlorobenzoyl) -1-Naphthylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-chlorophenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,4-dimethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)decylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-octylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-dimethylphosphine oxide Bis(2,6-dichloro-3,4,5-trimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, Bis(2,6-dichloro-3,4,5-trimethoxybenzoyl)-4-ethoxyphenylphosphine oxide, Bis(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, Bis(2-methyl-1-naphthoyl)-4-ethoxyphenylphosphine oxide, Bis(2-methyl-1-naphthoyl) 2-Naphthylphosphine oxide, bis(2-methyl-1-naphthoyl)-4-propylphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, bis(2-methoxy-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis(2-chloro-1-naphthoyl)-2,5-dimethylphenylphosphine oxide and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0130] The acylphosphine oxide compound preferably comprises at least one selected from the group consisting of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819", manufactured by IGM Resins BV) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (product name "Omnirad TPO-H", manufactured by IGM Resins BV).

[0131] When the ink contains a polymerization initiator, from the viewpoint of improving the curability of the ink, the content of the polymerization initiator relative to the total amount of ink is preferably 2% by mass or more, more preferably 5% by mass or more. There is no particular upper limit to the content of the polymerization initiator, for example, it is 10% by mass.

[0132] <surfactants> The ink preferably contains at least one surfactant. Known surfactants can be used as surfactants.

[0133] When the ink contains a surfactant, the surfactant content relative to the total amount of ink is preferably 0.1% to 2.0% by mass, more preferably 0.5% to 1.5% by mass.

[0134] <Polymerization Inhibitor> The ink of the present invention preferably contains at least one polymerization inhibitor.

[0135] Examples of polymerization inhibitors include p-methoxyphenol, quinones (e.g., hydroquinone, benzoquinone, methoxybenzoquinone, etc.), phenothiazines, catechols, alkylphenols (e.g., butylated hydroxytoluene (BHT), etc.), alkyl bisphenols, zinc dimethyl dithiocarbamate, copper dimethyl dithiocarbamate, copper dibutyl dithiocarbamate, copper salicylate, thiodipropionates, mercaptobenzimidazole, phosphites, 2,2,6,6-tetramethylpiperidin-1-oxy (TEMPO), 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxy (TEMPOL), and tris(N-nitroso-N-phenylhydroxyamine) aluminum salt (also known as CupferronAl).

[0136] The polymerization inhibitor preferably comprises at least one selected from the group consisting of p-methoxyphenol, catechols, quinones, alkylphenols, TEMPO, TEMPOL and tris(N-nitroso-N-phenylhydroxylamine) aluminum salt, and more preferably comprises at least one selected from the group consisting of p-methoxyphenol, hydroquinone, benzoquinone, BHT, TEMPO, TEMPOL and tris(N-nitroso-N-phenylhydroxylamine) aluminum salt.

[0137] When the ink contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.01% to 2.0% by mass relative to the total amount of ink, more preferably 0.02% to 1.0% by mass, and even more preferably 0.03% to 0.5% by mass.

[0138] <Additives> Depending on the requirements, the ink of the present invention may contain additives such as co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, solvents, and alkaline compounds.

[0139] <Physical Properties> The viscosity of the ink is preferably 0.5 mPa·s to 50 mPa·s, more preferably 5 mPa·s to 40 mPa·s, even more preferably 7 mPa·s to 35 mPa·s, and particularly preferably 8 mPa·s to 30 mPa·s. The viscosity is measured using a viscometer at 25°C, for example, using a TV-22 type viscometer manufactured by Toki Sangyo Co., Ltd.

[0140] The surface tension of the ink is preferably below 60 mN / m, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 45 mN / m. The surface tension is measured using a surface tension meter at 25°C, for example, using an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., and by the plate method.

[0141] [Image recording method] The image recording method of the present invention includes the following steps: applying the ink of the present invention described above to a substrate to record an image (hereinafter also referred to as the "ink application step"); and irradiating the ink applied to the substrate with active energy rays (hereinafter also referred to as the "active energy ray irradiation step").

[0142] The image recording method of the present invention may include other steps as needed.

[0143] Since the image recording method of the present invention uses the ink of the present invention to record images, the image recording method of the present invention can achieve the same effect as that obtained by using the ink of the present invention.

[0144] <Ink application process> There are no particular limitations on the method of applying ink; for example, well-known methods such as coating, inkjet recording, and immersion can be cited.

[0145] (Substrate) There is no particular limitation on the type of substrate; commonly known substrates can be used. Examples of substrates include glass, quartz, and plastic films. Examples of materials constituting plastic films include cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, acrylic resins, chlorinated polyolefin resins, polyethersulfone resins, polyethylene terephthalate (PET), polyethylene naphthalate, nylon, polyethylene, polystyrene, polypropylene, polycyclic olefins, polyimide, polycarbonate, and polyvinyl acetal. Plastic films can be films containing only one of these resins or films that blend two or more of them.

[0146] The thickness of the substrate is not particularly limited, for example, it is 1 μm to 10 mm. When the substrate is a thin film, the thickness is preferably 1 μm to 500 μm, more preferably 2 μm to 200 μm, even more preferably 5 μm to 100 μm, and particularly preferably 10 μm to 90 μm. Furthermore, when the substrate is glass, the thickness is preferably 0.1 mm to 10 mm, more preferably 0.15 mm to 8 mm, and even more preferably 0.2 mm to 5 mm.

[0147] (Inkjet recording method) There are no particular limitations on the inkjet recording method as long as it can record images, and known methods can be used. Examples of inkjet recording methods include charge control methods that use electrostatic induction to eject ink, on-demand inkjet methods (pressure pulse methods) that use the vibration pressure of piezoelectric elements, acoustic inkjet methods that convert electrical signals into sound beams and irradiate ink to eject ink using radiation pressure, and thermal inkjet methods that heat ink to form bubbles and use the resulting pressure (Bubble Jet (registered trademark)).

[0148] Examples of inkjet heads used in inkjet recording methods include the shuttle method, which uses a short serial head to scan and record along the width of the substrate, and the line head method, which uses a line head to arrange recording elements over the entire area corresponding to one side of the substrate.

[0149] In inline methods, patterns can be formed on the entire surface of the substrate by scanning the substrate in a direction intersecting the arrangement direction of the recording elements, eliminating the need for a transport system such as a carriage to scan short printheads. Furthermore, in inline methods, there is no need for carriage movement or complex scanning control of the substrate; only the substrate moves, thus enabling higher recording speeds compared to reciprocating methods.

[0150] The ink ejected from the inkjet head is preferably 1 pL (picoliter) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 50 pL.

[0151] <Active Energy Ray Irradiation Process> Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet light, and visible light. Among these, ultraviolet light is preferred.

[0152] The peak wavelength of the ultraviolet light is preferably 200nm to 405nm, more preferably 250nm to 400nm, and even more preferably 300nm to 400nm.

[0153] As a light source for ultraviolet irradiation, various lasers such as mercury lamps, gas lasers, and solid-state lasers are mainly used. Well-known examples include mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps. Furthermore, semiconductor light sources such as UV-LEDs (ultraviolet light-emitting diodes) and UV-LDs (ultraviolet laser diodes) are expected to be used as light sources for ultraviolet irradiation due to their small size, long lifespan, high efficiency, and low cost. Among these, metal halide lamps, high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, or UV-LEDs are preferred light sources for ultraviolet irradiation.

[0154] The irradiation energy (i.e., exposure dose) of the active energy rays is preferably 100 mJ / cm². 2 ~4000mJ / cm 2 More preferably 200 mJ / cm 2 ~2000mJ / cm 2 .

[0155] Example The following are embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0156] <Preparation of Yellow Pigment Dispersion 1> The following raw materials were mixed and stirred at 2,500 rpm for 10 minutes using a mixer (Silverson L4R) to obtain a mixture. The obtained mixture was then placed in a bead mill disperser (DISPERMAT LS (VMA)) and dispersed at 2,500 rpm for 6 hours using YTZ balls (NIKKATO CORPORATION) with a diameter of 0.65 mm to obtain a yellow pigment dispersion 1.

[0157] • PY184: Product name "Sicopal Yellow L 1100" (manufactured by DIC Corporation)... 40 parts by weight • Dispersant: Product name "Solsperse 32000" (manufactured by The Lubrizol Corporation)... 20 parts by weight • DVE-3: Triethylene glycol divinyl ether (manufactured by TCI)... 39 parts by weight FLORSTAB UV12…1.0 parts by weight (polymerization inhibitor; Cupferron Al, manufactured by Kromachem Ltd) <Preparation of Yellow Pigment Dispersion 2> PY184 was changed to PY110 (product name "Irgazin Yellow L 2040", manufactured by DIC Corporation). Otherwise, yellow pigment dispersion 2 was obtained by the same method as yellow pigment dispersion 1.

[0158] <Preparation of Yellow Pigment Dispersion 3> PY184 was changed to PY120 (product name "PV FAST YELLOW H2G", manufactured by Wiechmann), and otherwise, yellow pigment dispersion 3 was obtained by the same method as yellow pigment dispersion 1.

[0159] <Preparation of Yellow Pigment Dispersion 4> PY184 was changed to PY151 (product name "SYMULER FAST YELLOW 4GO", manufactured by DIC Corporation). Otherwise, yellow pigment dispersion 4 was obtained by the same method as yellow pigment dispersion 1.

[0160] [Examples 1-20, Comparative Examples 1-7] Yellow ink was prepared using the above-mentioned yellow pigment dispersion, such that the components shown in Tables 1 to 3 are present in the contents (mass %) shown in Tables 1 to 3.

[0161] In the example that includes PY184 as a yellow pigment, yellow pigment dispersion 1 was used.

[0162] In the example containing PY110 as a yellow pigment, yellow pigment dispersion 2 was used.

[0163] In the example that includes PY120 as a yellow pigment, yellow pigment dispersion 3 was used.

[0164] In the example that includes PY151 as a yellow pigment, yellow pigment dispersion 4 was used.

[0165] The detailed information of each component shown in Tables 1 to 3 is as follows.

[0166] (polymerizable monomer A) •NVC: N-vinylcaprolactam ACMO: Acryloylmorpholine VMOX: Vinylmethyloxazolidinone (polymeric monomer B) •CTFA: Cyclic Trimethylolpropane Formaldehyde Acrylate • CHA: Cyclohexyl acrylate ·BzA: Benzyl acrylate MEDOL-10: (2-Methyl-2-ethyl-1,3-dioxolane-4-yl)methacrylate (Other polymerizable monomers) • IBOA: Isoborneol Acrylate • DVE-3: Triethylene glycol divinyl ether ·3MPDDA: 3-Methyl-1,5-pentanediol diacrylate [Resin] • Acrylic resin 1: Dianal BR-113 (manufactured by Mitsubishi Chemical Corporation), Tg 75℃, weight average molecular weight 30,000 • Acrylic resin 2: Dianal BR-117 (manufactured by Mitsubishi Chemical Corporation), Tg 34℃, weight average molecular weight 140,000 Acrylic resin 3: ARUFON UC-3080 (manufactured by TOAGOSEI CO., LTD.), Tg 133℃, weight average molecular weight 14,000 • Polyester resin: DIAcron FC-1588 (manufactured by Mitsubishi Chemical Corporation), Tg 53℃, weight average molecular weight 30,000 (Polymerization initiator) Omnirad 184: 1-Hydroxycyclohexyl-phenyl ketone, manufactured by IGM Resins BV. Omnirad 819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM Resins BV. • Omnirad TPO-H: 2,4,6-Trimethylbenzoyl diphenylphosphine oxide, manufactured by IGM Resins BV [Polymerization Inhibitor] • UV12: Manufactured by Kromachem Ltd. (surfactant) BYK-307: A silicone surfactant manufactured by BYK Chemie. (Yellow pigment) PY110: Specific gravity 1.81 PY184: Specific gravity 5.6 PY120: Specific gravity 1.52 PY151: Specific gravity 1.55 <Image Recording> A polycarbonate substrate was prepared as the substrate.

[0167] The prepared yellow ink was filled into a UV inkjet printer (product name "UJF3042HG", manufactured by MIMAKI ENGINEERING CO., LTD.). The yellow ink was ejected from the printhead, recording a solid image on the substrate, thus obtaining an image record. The resolution was set to 1200 dpi (dots per inch) × 600 dpi. The UV exposure was set to 1100 mJ / cm². 2 .

[0168] <Evaluation> The above-mentioned image recordings and the above-mentioned yellow ink were evaluated as follows.

[0169] (Long-term weather resistance) The prepared image recorder was obtained by irradiating it with a metal halide lamp for 500 hours using an accelerated weathering test apparatus (product name "AI Super UV Tester SUV-W161", manufactured by IWASAKIELECTRIC CO., LTD.).

[0170] Hereinafter, the image recordings produced will be referred to as "image recordings M0", and the image recordings after the experiment will be referred to as "image recordings M1".

[0171] -Fade resistance- For image record M0 and image record M1, the CIE Lab values ​​were measured using a spectrochromatic meter (product name "CM-2600d", manufactured by KonicaMinolta, Inc.) under the conditions of light source D65, viewing angle 2°, and SCE (slight eccentricity reduction). a b Based on the measurement results, the color difference ΔE was calculated. The colorfastness was evaluated based on the color difference ΔE.

[0172] If the color difference ΔE is less than 3.0, the human eye will not perceive the color change. The evaluation criteria are as follows.

[0173] A: ΔE is below 1.0.

[0174] B: ΔE is greater than 1.0 and less than 2.0.

[0175] C: ΔE is greater than 2.0 and less than 3.0.

[0176] D: ΔE is greater than 3.0.

[0177] -Crack resistance- Image recording M1 was observed with the naked eye and under an optical microscope. The evaluation criteria are as follows.

[0178] A: There are no cracks in the image at all.

[0179] B: Cracks appear in the image, but the image is not peeled off from the substrate.

[0180] C: Cracks appear in the image, and a portion of the image peels off from the substrate.

[0181] D: Cracks appear in the image, and most of the image is peeled off from the substrate.

[0182] -Anti-adhesion- It was confirmed whether there was any adhesion on the surface of the image recording M1.

[0183] Furthermore, the image in image recording medium M1 was superimposed on coated paper (product name "OK Topcoat+", manufactured by OjiPaper Co., Ltd.) and left for 1 day. After placement, the presence or absence of image transfer from image recording medium M1 to the coated paper was confirmed. The evaluation criteria are as follows.

[0184] A: The surface of the image does not feel sticky, nor is there any image transfer.

[0185] B: The surface of the image is slightly viscous, but there is no image transfer.

[0186] C: The image is slightly transferred.

[0187] D: Image transfer.

[0188] (Color development) The yellow concentration of the image recording M0 was determined using a spectrochromometer (product name "FD-7", manufactured by Konica Minolta, Inc.). The evaluation criteria are as follows.

[0189] A: The yellow concentration is above 0.6.

[0190] B: The yellow concentration is above 0.4 and less than 0.6.

[0191] C: Yellow concentration is less than 0.4.

[0192] (Ejection) Using a UV inkjet printer (product name "UJF3042HG", manufactured by MIMAKI ENGINEERING CO., LTD.), after adjusting the nozzles to a zero setting, the absence of ink dots and ink splatter were visually observed during continuous printing at room temperature (25℃) for 1 hour. The average value of the results from three such operations was calculated. The evaluation criteria are as follows.

[0193] A: There are no missing ink dots or ink splatter, or fewer than 1.

[0194] B: There are more than one but fewer than two missing ink spots or ink splatter.

[0195] C: There are more than 2 missing ink spots or less than 6 ink splatters.

[0196] D: There are more than 6 missing ink dots or ink splatter.

[0197] The evaluation results are shown in Tables 1 to 3.

[0198] In the table, "Mp / D" refers to the ratio when the content of yellow pigment is set to Mp and the specific gravity of yellow pigment is set to D.

[0199] "Polymerizable monomer A + polymerizable monomer B" refers to the total content of polymerizable monomer A and polymerizable monomer B.

[0200] "Polymerizable monomer A / Polymerizable monomer B" refers to the mass ratio of the content of polymerizable monomer A to the content of polymerizable monomer B.

[0201] "The weighted average of Tg" refers to the weighted average of the glass transition temperatures when all polymerizable monomers contained in the ink are set as homopolymers.

[0202] [Table 1]

[0203] [Table 2]

[0204] [Table 3]

[0205] As shown in Tables 1 to 3, Examples 1 to 20 contain at least one yellow pigment selected from the group consisting of PY110 and PY184, polymerizable monomer A and polymerizable monomer B. The total content of polymerizable monomer A and polymerizable monomer B relative to the total amount of ink is more than 50% by mass, and the Mp / D is 1.0 to 2.0. Therefore, the long-term weather resistance (resistance to fading, cracking and adhesion) is excellent.

[0206] On the other hand, it can be seen that Comparative Example 1 and Comparative Example 2 do not contain at least one yellow pigment selected from the group consisting of PY110 and PY184, and have poor fading resistance.

[0207] It can be seen that in Comparative Example 3, the total content of polymerizable monomer A and polymerizable monomer B is less than 50% by mass, resulting in poor adhesion resistance.

[0208] It can be seen that Comparative Example 4 does not contain polymerizable monomer A and has poor resistance to adhesion.

[0209] It can be seen that Comparative Example 5 does not contain polymerizable monomer B and has poor crack resistance.

[0210] It can be seen that in Comparative Example 6, Mp / D exceeds 2.0, indicating poor crack resistance.

[0211] It can be seen that in Comparative Example 7, Mp / D is less than 1.0, indicating poor adhesion resistance.

[0212] It can be seen that in Example 1, the content of polymeric monomer A is more than 10% by mass relative to the total amount of ink, and the adhesion resistance is excellent compared with Example 6.

[0213] It can be seen that in Example 1, the content of polymerizable monomer A is less than 30% by mass relative to the total amount of ink, and compared with Example 7, the crack resistance and sprayability are excellent.

[0214] It can be seen that in Example 1, the weighted average of the glass transition temperatures when all the polymerizable monomers contained in the ink are set as homopolymers is above 20°C, which shows excellent anti-blocking properties compared with Example 8.

[0215] It can be seen that in Example 1, the weighted average of the glass transition temperatures when all the polymerizable monomers contained in the ink are set as homopolymers is below 70°C, which shows excellent crack resistance compared to Example 9.

[0216] It can be seen that in Example 1, the weighted average of the glass transition temperatures when all the polymerizable monomers contained in the ink are set as homopolymers is below 50°C. Compared with Example 10, the crack resistance and adhesion resistance are excellent.

[0217] It can be seen that in Example 1, the mass ratio of the content of polymeric monomer A to the content of polymeric monomer B is 0.1 or more, and compared with Example 11, the colorfastness and adhesion resistance are excellent.

[0218] It can be seen that in Example 1, the mass ratio of the content of polymeric monomer A to the content of polymeric monomer B is less than 0.5, and compared with Example 4, the crack resistance and ejection properties are excellent.

[0219] It can be seen that in Example 1, a polymeric monomer B with a glass transition temperature below 10°C is included, which has excellent crack resistance compared to Example 5.

[0220] It can be seen that in Example 1, a polymeric monomer B with a glass transition temperature below 10°C is included, which has excellent crack resistance compared to Example 5.

[0221] It is known that in Example 18, the resin containing a glass transition temperature of 40°C to 110°C has excellent anti-blocking properties compared to Example 13.

[0222] It is known that in Example 1, the (meth)acrylic resin containing a glass transition temperature of 40°C to 110°C exhibits superior anti-blocking properties compared to Example 18.

[0223] It is evident that in Example 1, the (meth)acrylic resin containing 0.2% by mass or more of a glass transition temperature of 40°C to 110°C exhibits superior anti-blocking properties compared to Example 14.

[0224] It is evident that in Example 1, the (meth)acrylic resin containing less than 2.0% by mass of a glass transition temperature of 40°C to 110°C exhibits superior sprayability compared to Example 15.

[0225] It can be seen that in Example 1, the glass transition temperature of the (meth)acrylic resin is above 40°C, and its anti-adhesion properties are excellent compared with those in Example 16.

[0226] It can be seen that in Example 1, the glass transition temperature of the (meth)acrylic resin is below 110°C, and its crack resistance is excellent compared with Example 17.

[0227] It can be seen that in Example 1, the yellow pigment is PY184, which has excellent color development and anti-blocking properties compared with Example 12.

[0228] Furthermore, the entire contents of the invention in Japanese Patent Application No. 2023-184792, filed on October 27, 2023, are incorporated herein by reference. Moreover, all documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as those specifically and separately described herein.

Claims

1. An active energy ray-curable yellow ink, comprising: Choose at least one yellow pigment from the group consisting of Pigment Yellow 110 and Pigment Yellow 184; Polymerizable monomer A, whose glass transition temperature as a homopolymer exceeds 60°C and contains nitrogen atoms; and Polymerizable monomer B, when used as a homopolymer, has a glass transition temperature below 60°C and is a monofunctional polymerizable monomer. The total content of polymeric monomer A and polymeric monomer B, relative to the total amount of the active energy radiation-curable yellow ink, is 50% by mass or more. When the content of the yellow pigment relative to the total amount of the active energy ray-curable yellow ink is set as Mp, and the specific gravity of the yellow pigment is set as D, Mp / D is 1.0 to 2.

0.

2. The active energy ray-curable yellow ink according to claim 1, wherein, The content of polymeric monomer A is 10% to 30% by mass relative to the total amount of the active energy ray curable yellow ink.

3. The active energy ray-curable yellow ink according to claim 1, wherein, The weighted average of the glass transition temperatures of all polymerizable monomers contained in the active energy ray-curable yellow ink when they are used as homopolymers is 20℃~70℃.

4. The active energy ray-curable yellow ink according to claim 1, wherein, The weighted average of the glass transition temperatures of all polymerizable monomers contained in the active energy ray-curable yellow ink when they are used as homopolymers is 20℃~50℃.

5. The active energy ray-curable yellow ink according to claim 1, wherein, The mass ratio of the content of polymeric monomer A to the content of polymeric monomer B is 0.1 to 0.

5.

6. The active energy radiation-curable yellow ink according to claim 1, wherein, When the polymerizable monomer B is used as a homopolymer, the glass transition temperature is below 10°C.

7. The active energy ray curable yellow ink according to claim 1, further comprising a resin with a glass transition temperature of 40°C to 110°C.

8. The active energy ray-curable yellow ink according to claim 7, wherein, The resin with a glass transition temperature of 40℃ to 110℃ is a (meth)acrylic resin with a glass transition temperature of 40℃ to 110℃.

9. The active energy ray-curable yellow ink according to claim 8, wherein, The amount of (meth)acrylic resin with a glass transition temperature of 40°C to 110°C is 0.2% to 2.0% by mass relative to the total amount of the active energy ray curable yellow ink.

10. The active energy ray-curable yellow ink according to claim 1, wherein, The yellow pigment is Pigment Yellow 184.

11. An image recording method, comprising the following steps: Applying the active energy radiation-curable yellow ink as described in any one of claims 1 to 10 to a substrate by inkjet recording; and The active energy radiation-curable yellow ink applied to the substrate is irradiated with active energy radiation.

Images