Method for producing laminate, inkjet ink, and image recording method

Abstract

Provided are a method for producing a laminate and an application thereof, the method comprising: a step for recording an image by applying an ink to a substrate containing a polymer containing vinyl chloride as a constituent unit by means of an ink jet recording method; and a step of disposing and laminating a laminate substrate containing a polymer containing vinyl chloride as a structural unit on the image, the ink containing a polymerizable monomer A having a cyclohexyl group, the content of the polymerizable monomer A being 20% by mass or more with respect to the total amount of the ink.

Description

Technical Field

[0001] The present invention relates to a method for producing a laminate, an inkjet ink and an image recording method. Background Art

[0002] Conventionally, various studies have been conducted on image recording using ink.

[0003] For example, Japanese Patent Gazette No. 2021-161182 describes an ink composition, which is an active energy ray-curable ink composition comprising (A) a polymerizable compound, (B) a photopolymerization initiator, (C) an ultraviolet absorber and / or (D) a free radical scavenger, characterized in that the (A) polymerizable compound comprises a monofunctional polymerizable compound and a polyfunctional polymerizable compound, and the monofunctional polymerizable compound comprises at least one monofunctional polymerizable compound (a) selected from the group consisting of a monofunctional polymerizable compound (a-1) having a molecular weight of less than 250 g / mol and a melting point of more than 25° C., a monofunctional polymerizable compound (a-2) having a molecular weight of less than 250 g / mol, a melting point below 25° C. and a viscosity of more than 20 mPa·s at 25° C., and a monofunctional polymerizable compound other than the monofunctional polymerizable compound (a-1) and the monofunctional polymerizable compound (a-2) and having an amide group and a cyclic structure. Summary of the invention

[0004] Technical issues to be solved by the invention

[0005] In some cases, after an image is recorded on an image recording substrate containing a polymer containing vinyl chloride as a structural unit (e.g., polyvinyl chloride) to obtain an image recorded material, a laminating substrate containing a polymer containing vinyl chloride as a structural unit is laminated on the image in the image recorded material to produce a laminate. In this case, it is required to improve the adhesion between the image recording substrate and the image, and the adhesion between the image and the laminating substrate.

[0006] The present invention has been made in view of such circumstances, and an object of one embodiment of the present invention is to provide a method for producing a laminate having excellent adhesion between a substrate and an image, the laminate comprising a polymer containing vinyl chloride as a structural unit.

[0007] Another embodiment of the present invention aims to provide an inkjet ink capable of recording an image having excellent adhesion to a substrate containing a polymer containing vinyl chloride as a structural unit.

[0008] Another embodiment of the present invention aims to provide an image recording method capable of recording an image having excellent adhesion to a substrate containing a polymer including vinyl chloride as a structural unit.

[0009] Means for solving technical problems

[0010] The present invention includes the following aspects.

[0011] <1> A method for producing a laminate, comprising: a step of recording an image by applying ink by an inkjet recording method on a substrate containing a polymer containing vinyl chloride as a structural unit; and a step of arranging a laminate substrate containing a polymer containing vinyl chloride as a structural unit on the image and laminating the image, wherein the ink contains a polymerizable monomer A having a cyclohexyl group, and the content of the polymerizable monomer A is 20% by mass or more relative to the total amount of the ink.

[0012] <2> according to <1> In the method for producing a laminate, the content of the polymerizable monomer A is 40% by mass or more relative to the total amount of the ink.

[0013] <3> according to <1> or <2> In the method for producing a laminate, a weighted average value of glass transition temperatures of all polymerizable monomers contained in the ink when they are respectively used as homopolymers is 0° C. to 100° C.

[0014] <4> according to <1> to <3> The method for producing a laminate according to any one of the preceding claims, wherein the proportion of the polymerizable monomer having a molecular weight of 205 or less in all polymerizable compounds contained in the ink is 90% by mass or more.

[0015] <5> according to <1> to <4> The method for producing a laminate according to any one of the preceding claims, wherein the ratio of the monofunctional polymerizable compound to all polymerizable compounds contained in the ink is 90% by mass or more.

[0016] <6> according to <1> to <5> The method for producing a laminate according to any one of the preceding claims, wherein the polymerizable monomer A contains at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate, and cyclohexyl(meth)acrylate.

[0017] <7> according to <1> to <6> The method for producing a laminate according to any one of the above aspects, wherein the polymerizable monomer A contains cyclohexyl (meth)acrylate.

[0018] <8> according to <1> to <7> The method for producing a laminated body described in any one of the above, wherein the ink further contains an N-vinyl compound.

[0019] <9> according to <8> The method for producing a laminated body, wherein the mass ratio of the content of the polymerizable monomer A to the content of the N-vinyl compound is 0.4 or more.

[0020] <10> according to <1> to <9> The method for producing a laminate according to any one of the preceding claims, wherein the ink further comprises a resin T containing at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms.

[0021] <11> according to <10> The method for producing a laminate, wherein the resin T contains a solubility parameter of 16.5 MPa 1 / 2 ~24.0MPa 1 / 2 The structural unit of the polymerizable monomer.

[0022] <12> according to <1> to <11> In any one of the methods for producing a laminate, the ink does not contain a surfactant, or the content of the surfactant is less than 0.1% by mass based on the total amount of the ink.

[0023] <13> according to <1> to <12> The method for producing a laminated body according to any one of the preceding claims, wherein in the lamination step, lamination is performed by overlapping the image and the lamination substrate so as to be in contact with each other.

[0024] <14> An inkjet ink comprising a polymerizable monomer A having a cyclohexyl group, wherein the content of the polymerizable monomer A is 30% by mass or more based on the total amount of the inkjet ink.

[0025] <15> according to <14> In the inkjet ink, the content of the polymerizable monomer A is 40% by mass or more relative to the total amount of the inkjet ink.

[0026] <16> according to <14> or <15> The inkjet ink has a weighted average glass transition temperature of 0°C to 100°C when all polymerizable monomers contained in the inkjet ink are respectively used as homopolymers.

[0027] <17> according to <14> to <16> The inkjet ink described in any one of the preceding claims, wherein the proportion of the polymerizable monomer having a molecular weight of 205 or less in all polymerizable compounds contained in the inkjet ink is 90% by mass or more.

[0028] <18> according to <14> to <17> The inkjet ink described in any one of the preceding claims, wherein the ratio of the monofunctional polymerizable compound to all polymerizable compounds contained in the inkjet ink is 90% by mass or more.

[0029] <19> according to <14> to <18> The inkjet ink described in any one of the preceding claims, wherein the polymerizable monomer A comprises at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0030] <20> according to <14> to <19> The inkjet ink described in any one of the preceding claims, wherein the polymerizable monomer A comprises cyclohexyl (meth)acrylate.

[0031] <21> according to <14> to <20> The inkjet ink described in any one of the preceding claims, wherein the inkjet ink further comprises an N-vinyl compound.

[0032] <22> according to <21> In the inkjet ink, the mass ratio of the content of the polymerizable monomer A to the content of the N-vinyl compound is 0.4 or more.

[0033] <23> according to <14> to <22> The inkjet ink described in any one of the preceding claims, further comprising a resin T containing at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms.

[0034] <24> according to <23> The inkjet ink, wherein the resin T contains a solubility parameter of 16.5 MPa 1 / 2 ~24.0MPa 1 / 2 The structural unit of the polymerizable monomer.

[0035] <25> according to <14> to <24> The inkjet ink described in any one of the preceding claims, wherein the inkjet ink does not contain a surfactant, or the content of the surfactant is less than 0.1% by mass based on the total amount of the inkjet ink.

[0036] <26> An image recording method comprising imparting an image to a substrate containing a polymer containing vinyl chloride as a structural unit by inkjet recording <14> to <25> A process for recording an image using any one of the inkjet inks.

[0037] Effects of the Invention

[0038] According to one embodiment of the present invention, there is provided a method for producing a laminate having excellent adhesion between a substrate including a polymer containing vinyl chloride as a structural unit and an image.

[0039] According to another embodiment of the present invention, there is provided an inkjet ink capable of recording an image having excellent adhesion to a substrate containing a polymer containing vinyl chloride as a structural unit.

[0040] According to another embodiment of the present invention, there is provided an image recording method capable of recording an image having excellent adhesion to a substrate including a polymer containing vinyl chloride as a structural unit. DETAILED DESCRIPTION

[0041] Hereinafter, the method for producing a laminate, the inkjet ink, and the image recording method of the present invention will be described in detail.

[0042] In the present specification, a numerical range expressed using "to" indicates a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0043] In the numerical ranges recorded in this specification, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical ranges recorded in this specification, the upper limit or lower limit recorded in a certain numerical range can be replaced by the value shown in the embodiment.

[0044] In the present specification, when a plurality of substances corresponding to each component are present in a composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified.

[0045] In the present specification, a combination of two or more preferred aspects is a more preferred aspect.

[0046] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0047] In this specification, "image" refers to the entire film formed by sequentially applying the pretreatment liquid and the ink, and "image recording" refers to the formation of an image (ie, film).

[0048] Furthermore, the concept of “image” in this specification also includes a solid image.

[0049] In this specification, "(meth)acrylate" is a concept including both acrylate and methacrylate. Also, "(meth)acrylic acid" is a concept including both acrylic acid and methacrylic acid.

[0050] [Method for producing laminate]

[0051] The method for producing a laminate of the present invention comprises: a step of recording an image by applying ink by an inkjet recording method on a substrate containing a polymer containing vinyl chloride as a structural unit (hereinafter also referred to as an "image recording step"); and a step of arranging a laminating substrate containing a polymer containing vinyl chloride as a structural unit on the image and laminating the image (hereinafter also referred to as a "lamination step"), wherein the ink contains a polymerizable monomer A having a cyclohexyl group, and the content of the polymerizable monomer A is 20% by mass or more relative to the total amount of the ink.

[0052] According to the method for manufacturing a laminate of the present invention, a laminate comprising an image recording substrate, an image recorded on the image recording substrate, and a laminating substrate arranged on the image in sequence can be obtained. The laminate obtained by the method for manufacturing a laminate of the present invention has excellent adhesion between the image recording substrate and the image, and between the image and the laminating substrate.

[0053] The reason why the above-mentioned effects are exerted by the method for producing a laminate of the present invention is presumed to be as follows.

[0054] The ink used in the method for producing a laminate of the present invention contains a polymerizable monomer A having a cyclohexyl group, and the content of the polymerizable monomer A is 20% by mass or more relative to the total amount of the ink. The polymerizable monomer A having a cyclohexyl group has a high affinity with a polymer containing vinyl chloride as a structural unit contained in an image recording substrate, and has excellent solubility with respect to the image recording substrate. It is believed that by polymerizing in a state where a part of the ink is dissolved with respect to the image recording substrate, the adhesion between the image recording substrate and the image is excellent.

[0055] Furthermore, the ink film (ie, image) obtained by curing the ink containing the polymerizable monomer A having a cyclohexyl group has excellent thermal softening properties. Therefore, it is considered that the image has excellent adhesion to the lamination substrate.

[0056] Japanese Patent Application Laid-Open No. 2021-161182 does not describe focusing on the interaction between the ink or the ink film formed by curing of the ink and a substrate containing a polymer containing vinyl chloride as a structural unit.

[0057] Hereinafter, each step in the method for producing the laminate of the present invention will be described.

[0058] <<Image Recording Process>>

[0059] The image recording step is a step of recording an image by applying ink by an inkjet recording method on an image recording substrate containing a polymer containing vinyl chloride as a structural unit.

[0060] <Image Recording Base Material>

[0061] The image recording substrate contains a polymer including vinyl chloride as a structural unit.

[0062] The polymer including vinyl chloride as a structural unit may be a homopolymer of vinyl chloride (ie, polyvinyl chloride), or may be a copolymer including vinyl chloride and a monomer other than vinyl chloride as structural units.

[0063] Examples of the copolymer containing vinyl chloride and other monomers other than vinyl chloride as structural units include vinyl chloride-urethane copolymers, vinyl chloride-ethylene copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic acid copolymers, vinyl chloride-vinyl acetate-vinyl alcohol copolymers, and vinyl chloride-ethylene-vinyl acetate copolymers.

[0064] Among them, the image recording substrate preferably contains polyvinyl chloride.

[0065] The image recording substrate may contain other components in addition to the polymer containing vinyl chloride as a structural unit. Examples of other components include a plasticizer, a stabilizer, an antioxidant, an ultraviolet absorber, a binder resin, and a white pigment.

[0066] The image recording substrate may have a layer containing a polymer containing vinyl chloride as a structural unit and a surface treatment layer, but preferably has no surface treatment layer from the viewpoint of obtaining adhesion between the image recording substrate and the image by dissolving the ink in the image recording substrate. That is, the surface of the image recording substrate to which the ink is applied preferably contains a polymer containing vinyl chloride as a structural unit.

[0067] The thickness of the image recording substrate is not particularly limited, but is, for example, preferably 0.1 μm to 1,000 μm, more preferably 0.1 μm to 800 μm, and further preferably 1 μm to 500 μm.

[0068] <Ink>

[0069] The ink contains a polymerizable monomer A having a cyclohexyl group. Hereinafter, the polymerizable monomer having a cyclohexyl group is also simply referred to as “polymerizable monomer A”.

[0070] (Polymerizable Monomer A)

[0071] The ink contains at least one polymerizable monomer A.

[0072] In the present invention, the "polymerizable monomer" refers to a compound having a polymerizable group and having a molecular weight of not more than 1000. The molecular weight is calculated based on the types and numbers of atoms constituting the compound.

[0073] The type of the polymerizable group contained in the polymerizable monomer A is not particularly limited, but from the viewpoint of curability, a (meth)acryloyl group (preferably an acryloyl group) is preferred, and a (meth)acryloyloxy group (preferably an acryloyloxy group) is more preferred.

[0074] The number of polymerizable groups contained in the polymerizable monomer A may be only one or may be two or more, but is preferably only one.

[0075] The cyclohexyl group contained in the polymerizable monomer A may have a substituent. However, the substituents do not form a ring with each other. For example, isobornyl and decahydronaphthyl are not included in the concept of cyclohexyl.

[0076] The number of the cyclohexyl groups contained in the polymerizable monomer A may be only one or may be two or more, but is preferably only one.

[0077] The molecular weight of the polymerizable monomer A is preferably 205 or less, and more preferably 180 or less. The molecular weight of the polymerizable monomer A of 205 or less indicates a relatively low molecular weight, and by setting it to 205 or less, the ink is easily dissolved in the image recording substrate. As a result, the adhesion between the image recording substrate and the ink film is improved. In addition, when the molecular weight of the polymerizable monomer A is 205 or less, the distance between the crosslinking points becomes shorter, and the density of the ink film increases, so the peel strength becomes higher.

[0078] The lower limit of the molecular weight of the polymerizable monomer A is not particularly limited, and is 100, for example.

[0079] Examples of the polymerizable monomer A include 4-tert-butylcyclohexyl(meth)acrylate, 3,3,5-trimethylcyclohexyl(meth)acrylate, cyclohexyl(meth)acrylate, 1,4-dimethanol monocyclohexyl(meth)acrylate, vinylcyclohexane, and cyclohexyl vinyl ether.

[0080] Among them, from the viewpoint of improving the adhesion to the image recording substrate and the adhesion to the laminating substrate, the polymerizable monomer A preferably contains at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate, cyclohexyl(meth)acrylate and 1,4-dimethanol monocyclohexyl(meth)acrylate, more preferably contains at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate and cyclohexyl(meth)acrylate, and further preferably contains cyclohexyl(meth)acrylate.

[0081] The content of polymerizable monomer A is 20% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more relative to the total amount of ink. In consideration of the balance with other components, the upper limit of the content of polymerizable monomer A is preferably 80% by mass.

[0082] When the content of the polymerizable monomer A is 20% by mass or more, the solubility in the image recording substrate containing the polymer containing vinyl chloride as a structural unit is excellent, and the thermal softening property of the ink film (i.e., image) formed by the ink is excellent. As a result, the adhesion between the image and the image recording substrate and the adhesion between the image and the laminating substrate are excellent.

[0083] (N-vinyl compound)

[0084] The ink preferably comprises at least one N-vinyl compound.

[0085] N-vinyl compounds are compounds in which a vinyl group is bonded to a nitrogen atom.

[0086] The N-vinyl compound has high solubility in the image recording substrate and therefore contributes to the adhesion between the image recording substrate and the image.

[0087] Examples of the N-vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, N-vinylimidazole, N-vinylphthalimide, N-vinylacetamide, N-vinylformamide, and 5-methyl-3-vinyl-2-oxazolidinone.

[0088] Among them, the N-vinyl compound is preferably at least one selected from the group consisting of N-vinylcaprolactam and 5-methyl-3-vinyl-2-oxazolidinone from the viewpoint of high solubility in the image recording substrate and improved adhesion between the image recording substrate and the image.

[0089] The content of the N-vinyl compound is preferably 5% by mass to 70% by mass, more preferably 10% by mass to 60% by mass, and even more preferably 20% by mass to 50% by mass, based on the total amount of the ink.

[0090] The mass ratio of the content of polymerizable monomer A to the content of N-vinyl compound is preferably 0.4 or more, more preferably 0.5 or more, further preferably 0.7 or more, and more preferably 0.9 or more. If the mass ratio is 0.4 or more, the curability of the ink is improved, and the adhesion between the image and the lamination substrate is improved.

[0091] The upper limit of the mass ratio is not particularly limited, but is preferably 4.0 from the viewpoint of obtaining thermal softening properties in the ink film.

[0092] In the ink used for image recording, the weighted average value of the glass transition temperatures of all polymerizable monomers contained in the ink as homopolymers is 0° C. to 100° C., preferably 10° C. to 60° C. When the weighted average value is 0° C. to 100° C., the ink film (i.e., image) obtained by curing the ink has excellent thermal softening properties, so the image has excellent adhesion to the lamination substrate.

[0093] The glass transition temperature when the polymerizable monomer is a homopolymer is measured by the following method. In addition, the "polymerizable monomer" mentioned here refers to a compound having a polymerizable group and a molecular weight of 1,000 or less.

[0094] First, a homopolymer having a weight average molecular weight of 10,000 to 20,000 is produced using a polymerizable monomer. The glass transition temperature of the produced homopolymer is measured according to the method described in JIS K7121:2012.

[0095] In the present invention, the glass transition temperature is measured using a differential scanning calorimeter, for example, "DSC-60" manufactured by SHIMADZUCORPORATION.

[0096] In the present invention, the weight average molecular weight is measured using gel permeation chromatography (GPC). For example, as GPC, HLC-8220GPC (manufactured by TOSOH CORPORATION) is used, as a column, 3 TSK gels, Super MultiporeHZ-H (manufactured by TOSOH CORPORATION, 4.6 mmID×15 cm) are used, and as an eluent, THF (tetrahydrofuran) is used. As conditions, the sample concentration is set to 0.45% by mass, the flow rate is set to 0.35 ml / min, the sample injection amount is set to 10 μl, the measurement temperature is set to 40°C, and a differential refractive index (RI) detector is used for detection. The calibration curve is made using the product name "TSK standard polystyrene" manufactured by Tosoh Corporation: 8 samples of "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000" and "n-propylbenzene" as standard samples.

[0097] In addition, the glass transition temperature of the homopolymer varies depending on the weight average molecular weight of the homopolymer, but when the weight average molecular weight is 10,000 to 20,000, the variation is so small that it can be ignored.

[0098] The weighted average value of the glass transition temperature is calculated using the following formula. i represents the glass transition temperature of the i-th polymerizable monomer contained in the ink as a homopolymer, C i It represents the content (mass %) of the i-th polymerizable monomer relative to the total amount of ink.

[0099] Weighted average of glass transition temperatures = ΣT i C i / ΣC i

[0100] (Other polymerizable compounds)

[0101] The ink may contain polymerizable compounds other than the polymerizable monomer A and the N-vinyl compound as other polymerizable compounds. However, it is preferred that the type and content of the other polymerizable compounds be adjusted so that the weighted average value of the glass transition temperatures of all the polymerizable monomers contained in the ink as homopolymers is 0° C. to 100° C.

[0102] The polymerizable group possessed by the other polymerizable compounds is preferably a free radical polymerizable group, more preferably a photoradical polymerizable group, and still more preferably an ethylenically unsaturated group. Examples of the other polymerizable compounds include (meth)acrylate compounds, (meth)acrylamide compounds, vinyl ether compounds, allyl compounds, and unsaturated carboxylic acids.

[0103] The proportion of polymerizable monomers with a molecular weight of 205 or less in all polymerizable compounds contained in the ink is preferably 90% by mass or more, more preferably 95% by mass or more. If the above proportion is 90% by mass or more, the solubility of the ink relative to the image recording substrate becomes higher, and the adhesion of the image recording substrate to the image is improved. The upper limit of the above proportion is not particularly limited, and the above proportion can be 100% by mass. That is, all polymerizable compounds contained in the ink can be polymerizable monomers with a molecular weight of 205 or less.

[0104] In addition, the "polymerizable compound" referred to herein means a compound having at least one polymerizable group, and the molecular weight is not particularly limited.

[0105] The proportion of monofunctional polymerizable compounds in all polymerizable compounds contained in the ink is preferably 90% by mass or more, more preferably 92% by mass or more. If the above ratio is 90% by mass or more, the curing shrinkage caused by residual stress is suppressed, and the adhesion of the image recording substrate to the image is improved. The upper limit of the above ratio is not particularly limited, and the above ratio can be 100% by mass. That is, all polymerizable compounds contained in the ink can be monofunctional polymerizable compounds.

[0106] In addition, the "polymerizable compound" referred to herein refers to a compound having at least one polymerizable group, and the molecular weight is not particularly limited. The "monofunctional polymerizable compound" refers to a compound having one polymerizable group.

[0107] (Polymerization initiator)

[0108] The ink preferably contains at least one polymerization initiator.

[0109] As the polymerization initiator, a photoradical polymerization initiator that absorbs light to generate radicals as polymerization initiating species is preferred.

[0110] Examples of the polymerization initiator include alkylphenone compounds, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0111] Among them, the polymerization initiator is preferably at least one selected from the group consisting of acylphosphine compounds and thio compounds, more preferably at least one selected from the group consisting of acylphosphine oxide compounds and thioxanthone compounds, and further preferably, an acylphosphine oxide compound and a thioxanthone compound are used simultaneously.

[0112] Examples of the acylphosphine oxide compound include monoacylphosphine oxide compounds and bisacylphosphine oxide compounds, and bisacylphosphine oxide compounds are preferred.

[0113] Examples of the monoacylphosphine oxide compound include isobutyryldiphenylphosphine oxide, 2-ethylhexanoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, o-toluoyldiphenylphosphine oxide, p-tert-butylbenzoyldiphenylphosphine oxide, 3-pyridylcarbonyldiphenylphosphine oxide, acryloyldiphenylphosphine oxide, benzoyldiphenylphosphine oxide, and pivaloylphenylphosphine oxide. 4-(tert-butyl)benzoyldiphenylphosphine oxide, terephthaloylbisdiphenylphosphine oxide, 2-methylbenzoyldiphenylphosphine oxide, neodecanoyldiphenylphosphine oxide, 2-methyl-2-ethylhexanoyldiphenylphosphine oxide, 1-methyl-cyclohexanoyldiphenylphosphine oxide, methyl pivaloylphenylphosphinate and isopropyl pivaloylphenylphosphinate.

[0114] Examples of the bisacylphosphine oxide compound include 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, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-ethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, 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-dimethoxyphenylphosphine oxide Methylphenylphosphine 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)- 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.

[0115] Among them, the acylphosphine oxide compound preferably includes 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-trimethylbenzoyldiphenylphosphine oxide (product name "Omnirad TPO-H", manufactured by IGM Resins BV).

[0116] Examples of the thioxanthone compound include thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)thioxanthone, 4-butoxycarbonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfonylthioxanthone, 3,4-bis[2-(2-methoxyethoxy)ethoxycarbonyl]thioxanthone, 1-ethoxycarbonyl -3-(1-methyl-1-morpholinoethyl)thioxanthone, 2-methyl-6-dimethoxymethylthioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, n-allylthioxanthone-3,4-dicarboxylic imide, n-octylthioxanthone-3,4-dicarboxylic imide, N-(1,1,3,3-tetramethylbutyl)thioxanthone-3,4-dicarboxylic imide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy)-N,N,N-trimethyl-1-propaneammonium chloride.

[0117] The thioxanthone compound may be a commercially available product. Examples of the commercially available product include the SPEEDCURE series manufactured by Lambson (eg, SPEEDCURE 7010, SPEEDCURE CPTX, SPEEDCURE ITX, etc.).

[0118] When the ink contains a polymerization initiator, from the viewpoint of improving the curability of the ink, the content of the polymerization initiator is preferably 2% by mass or more, more preferably 5% by mass or more, relative to the total amount of the ink. The upper limit of the content of the polymerization initiator is not particularly limited, and is, for example, 10% by mass.

[0119] (Surfactant)

[0120] The ink may contain at least one surfactant. In the present invention, the surfactant refers to a compound having a surface active function with a molecular weight of less than 1000. The molecular weight is calculated based on the type and number of atoms constituting the compound.

[0121] However, from the viewpoint of improving the affinity between the image recording substrate and the ink, the ink preferably does not contain a surfactant, or the content of the surfactant is less than 0.1% by mass relative to the total amount of the ink. When the ink contains a surfactant, a commonly known surfactant can be used as the surfactant.

[0122] (Inhibitor)

[0123] The inks of the present invention preferably comprise at least one polymerization inhibitor.

[0124] Examples of the polymerization inhibitor include p-methoxyphenol, quinones (e.g., hydroquinone, benzoquinone, methoxybenzoquinone, etc.), phenothiazines, catechols, alkylphenols (e.g., butylhydroxytoluene (BHT)), alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionate esters, mercaptobenzimidazole, phosphorous acids, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl (TEMPOL), and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt (also known as Cupferron Al).

[0125] Among them, the polymerization inhibitor preferably includes 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 includes at least one selected from the group consisting of p-methoxyphenol, hydroquinone, benzoquinone, BHT, TEMPO, TEMPOL and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt.

[0126] When the ink contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.01 to 2.0% by mass, more preferably 0.02 to 1.0% by mass, and further preferably 0.03 to 0.5% by mass, based on the total amount of the ink.

[0127] (resin)

[0128] The ink may contain at least one resin. As the resin that the ink may contain, the resin T described below can be cited. The ink preferably does not contain any resin other than the resin T described below. In the present invention, the "resin" does not have a polymerizable group. In the present invention, a resin having a polymerizable group is equivalent to a "polymerizable compound" and is distinguished from a resin. In addition, the resin refers to a compound having a weight average molecular weight of 1000 or more.

[0129] -Resin T-

[0130] The ink preferably contains a resin T containing at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms. If the resin contains at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms, the solubility of the ink in the image recording substrate becomes higher, and the adhesion between the image recording substrate and the image is improved.

[0131] The fluorinated hydrocarbon group refers to a hydrocarbon group substituted with at least one fluorine atom.

[0132] Examples of the fluorinated hydrocarbon group include a fluorinated alkyl group, a fluorinated alkenyl group, and a fluorinated aryl group.

[0133] The fluorinated hydrocarbon group is preferably a fluorinated alkyl group, and particularly preferably a perfluoroalkyl group.

[0134] The number of fluorine atoms in the fluorinated hydrocarbon group is preferably 6 or more, more preferably 8 or more.

[0135] The upper limit of the number of fluorine atoms in the fluorinated hydrocarbon group is not particularly limited, and 40 is exemplified as the upper limit.

[0136] The number of carbon atoms in the fluorinated hydrocarbon group is preferably 3 or more, more preferably 4 or more.

[0137] The upper limit of the number of carbon atoms in the fluorinated hydrocarbon group is not particularly limited, and 20 is exemplified as the upper limit.

[0138] Examples of the hydrocarbon group having 12 or more carbon atoms include alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, aralkyl groups, etc. As the hydrocarbon group having 12 or more carbon atoms, an alkyl group is particularly preferred.

[0139] The number of carbon atoms in the hydrocarbon group having 12 or more carbon atoms is preferably 14 or more, more preferably 16 or more.

[0140] The upper limit of the number of carbon atoms in the hydrocarbon group having 12 or more carbon atoms is not particularly limited, and 30 is exemplified as the upper limit.

[0141] The polysiloxane group refers to a repeating divalent group containing a Si—O bond.

[0142] The specific resin more preferably contains a monovalent group containing a polysiloxane group.

[0143] Examples of the monovalent group containing a polysiloxane group include the following groups (P).

[0144] [Chemical formula 1]

[0145]

[0146] In the basis (P), R P1 and R P2Each independently represents a hydrocarbon group having 1 to 6 carbon atoms or the following group (Z), R P3 ~R P5 Each independently represents a hydrocarbon group having 1 to 6 carbon atoms, x represents an integer of 1 to 100, and * represents a bonding position.

[0147] When x is an integer greater than 2, there are multiple R P1 Can be the same or different, there are multiple R P2 Can be the same or different.

[0148] In the group (P), the number of Si—O bonds (ie, siloxane bonds) is 2 or more.

[0149] [Chemical formula 2]

[0150]

[0151] In the basis (Z), R Z1 ~R Z5 Each independently represents a hydrocarbon group having 1 to 6 carbon atoms, z represents an integer of 0 to 100, and * represents a bonding position.

[0152] When z is an integer greater than 2, there are multiple R Z1 Can be the same or different, there are multiple R Z2 Can be the same or different.

[0153] As x in the group (P), an integer of 1-50 is preferable, an integer of 1-20 is more preferable, and an integer of 1-10 is particularly preferable.

[0154] In the basis (P), as R P1 ~R P5 The hydrocarbon group having 1 to 6 carbon atoms in is each independently preferably a methyl group, an ethyl group or a phenyl group, more preferably a methyl group or a phenyl group, and particularly preferably a methyl group.

[0155] As z in the group (Z), an integer of 0-50 is preferable, an integer of 0-20 is more preferable, and an integer of 0-10 is particularly preferable.

[0156] In the basis (Z), as R Z1 ~R Z5 The hydrocarbon group having 1 to 6 carbon atoms in is each independently preferably a methyl group, an ethyl group or a phenyl group, more preferably a methyl group or a phenyl group, and particularly preferably a methyl group.

[0157] - a structural unit (1) comprising at least one selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms-

[0158] The resin T preferably contains at least one structural unit (1) containing at least one selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms.

[0159] Examples of the structural unit (1) include a structural unit derived from a vinyl monomer (for example, (meth)acrylate, (meth)acrylamide, etc.), a structural unit derived from a diol compound, and a structural unit derived from a diisocyanate compound.

[0160] As the structural unit (1), a structural unit derived from a (meth)acrylic acid ester is preferred, and the following structural unit (1A) is more preferred.

[0161] [Chemical formula 3]

[0162]

[0163] In structural unit (1A), R 31 represents a hydrogen atom or a methyl group, L 31 represents a single bond or a connecting group, X 31 represents a fluorinated hydrocarbon group, a monovalent group including a polysiloxane group, or a hydrocarbon group having 12 or more carbon atoms, and two *s each represent a bonding position.

[0164] X 31 Preferred embodiments of the fluorinated hydrocarbon group, the monovalent group containing a polysiloxane group, and the hydrocarbon group having 12 or more carbon atoms are as described above.

[0165] R 31 represents a hydrogen atom or a methyl group, and is preferably a methyl group.

[0166] As L 31 The linking group represented is preferably a divalent hydrocarbon group having 1 to 11 carbon atoms (more preferably 2 to 11 carbon atoms, and even more preferably 2 to 8 carbon atoms).

[0167] The above-mentioned divalent hydrocarbon group may have a substituent such as a hydroxyl group or an alkoxy group.

[0168] Examples of the divalent hydrocarbon group include an alkylene group, an alkenylene group, an arylene group, an alkylenearylene group, an alkylenearylenealkylene group, an alkylenecarbonyloxyalkylene group, and an arylenecarbonyloxyalkylene group.

[0169] As the divalent hydrocarbon group, an alkylene group having 1 to 11 carbon atoms (more preferably 1 to 6 carbon atoms) is particularly preferred.

[0170] Specific examples of the structural unit (1A) containing at least one selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms are as follows.

[0171] [Chemical formula 4]

[0172]

[0173] [Chemical formula 5]

[0174]

[0175] Specific examples of the structural unit (1) include the following structural units.

[0176] [Chemical formula 6]

[0177]

[0178] The resin T preferably contains, in addition to the above-mentioned structural unit (1), at least one structural unit (2) containing at least one selected from the group consisting of an alkylthio group, an alkylenethio group and a mercapto group.

[0179] Examples of the structural unit (2) include alkylthio, alkylenethioalkylene, alkyleneoxythioalkyleneoxy (preferably having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms), mercapto, mercaptoalkyl (preferably having 1 to 10 carbon atoms), mercaptoalkylamino (preferably having 1 to 10 carbon atoms), and the like.

[0180] The alkylthio group has preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, further preferably 6 to 20 carbon atoms, and particularly preferably 10 to 20 carbon atoms, from the viewpoint of further suppressing yellowing of an image.

[0181] The alkylenethioalkylene group preferably has 2 to 20 carbon atoms, and more preferably 2 to 10 carbon atoms, from the viewpoint of further suppressing yellowing of an image.

[0182] Furthermore, examples of the structural unit (2) include structural units derived from a vinyl monomer containing at least one selected from the group consisting of an alkylthio group, an alkylenethioalkylene group and a mercapto group (for example, (meth)acrylate, (meth)acrylamide, etc.).

[0183] The structural unit (2) comprising at least one selected from the group consisting of an alkylthio group, an alkylenethio group and a mercapto group is preferably an alkylthio group, and particularly preferably an alkylthio group as a terminal group of the main chain of the resin T, from the viewpoint of further suppressing yellowing of the image.

[0184] Specific examples of the structural unit (2) are as follows.

[0185]

[0186] [Chemical formula 7]

[0187]

[0188] The resin T preferably contains at least one structural unit (3) containing an amine structure having an α-hydrogen atom in addition to the structural unit (1).

[0189] Examples of the structural unit (3) include structural units derived from vinyl monomers (for example, (meth)acrylates, (meth)acrylamide, etc.), structural units derived from diol compounds, structural units derived from diamine compounds, and structural units derived from diisocyanate compounds.

[0190] Here, the (meth)acrylate is a raw material of a (meth)acrylic resin, the diisocyanate compound is a raw material of a urethane resin or a urea resin, the diol compound is a raw material of a urethane resin, and the diamine compound is a raw material of a urea resin.

[0191] As the structural unit (3), a structural unit derived from a (meth)acrylic acid ester is preferred, and the following structural unit (3A) is more preferred.

[0192] [Chemical formula 8]

[0193]

[0194] In structural unit (3A), R 11 represents a hydrogen atom or a methyl group, R 12 , R 13 and R 14 Each independently represents a hydrogen atom or a hydrocarbon group, L 11 Represents a linking group, and two *s represent bonding positions. 12 With L 11 Can be connected to form a ring, R 12 With R 13 Can be connected to each other to form a ring.

[0195] In structural unit (3A), R 11 represents a hydrogen atom or a methyl group, and is preferably a methyl group.

[0196] In the structural unit (3A), as R 12 , R 13 and R 14 The number of carbon atoms of the hydrocarbon groups in each independently is preferably 1 to 11, more preferably 1 to 6, and particularly preferably 1 to 3.

[0197] As R 12 , R 13 and R 14 The hydrocarbon group in includes an alkyl group, an alkenyl group, an aryl group, an alkylaryl group, an aralkyl group and the like, preferably an alkyl group or an aryl group, and more preferably an alkyl group.

[0198] R12 , R 13 and R 14 The hydrocarbon group in may be substituted. Examples of the substituent in this case include a hydroxyl group, an alkoxy group, and the like.

[0199] As R 13 and R 14 From the viewpoint of further suppressing the stickiness of the image, each independently is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and still more preferably a hydrogen atom or a methyl group.

[0200] As R 13 and R 14 In order to further suppress the stickiness of the image, it is particularly preferred that all of them are hydrogen atoms. 13 and R 14 The hydrogen atoms in R are all alpha hydrogen atoms. 13 and R 14 When all of them are hydrogen atoms, the number of α hydrogen atoms in the amine structure is large, and thus the function of the amine structure (that is, the function of suppressing inhibition of radical polymerization caused by oxygen) is more effectively exerted. Therefore, in this case, the stickiness of the image is significantly suppressed.

[0201] As R 12 From the viewpoint of further suppressing the stickiness of the image, a hydrocarbon group is preferred, an alkyl group having 1 to 6 carbon atoms is more preferred, an alkyl group having 1 to 3 carbon atoms is further preferred, a methyl group or an ethyl group is further preferred, and a methyl group is particularly preferred.

[0202] In R 12 When it is a hydrocarbon group (more preferably as described above), R 12 Compared with the case where the atoms are hydrogen atoms, the stickiness of the image is suppressed. This is believed to be because 12 In the case of a hydrocarbon group (a more preferred embodiment is as described above), the formation of NO radicals is suppressed, and as a result, the function of the amine structure (that is, the function of suppressing inhibition of radical polymerization caused by oxygen) is more effectively exhibited.

[0203] In structural unit (3A), L 11 Represents a linker.

[0204] As L 11 The linking group represented by is preferably a divalent hydrocarbon group having 1 to 11 carbon atoms (more preferably 2 to 11 carbon atoms, and further preferably 2 to 8 carbon atoms).

[0205] The above-mentioned divalent hydrocarbon group may have a substituent such as a hydroxyl group or an alkoxy group.

[0206] Examples of the divalent hydrocarbon group include an alkylene group, an alkenylene group, an arylene group, an alkylenearylene group, an alkylenearylenealkylene group, an alkylenecarbonyloxyalkylene group, and an arylenecarbonyloxyalkylene group.

[0207] As the divalent hydrocarbon group, an alkylene group having 1 to 11 carbon atoms (more preferably 1 to 6 carbon atoms) is particularly preferred.

[0208] Specific examples of the structural unit (3) are as follows.

[0209] [Chemical formula 9]

[0210]

[0211] [Chemical formula 10]

[0212]

[0213] In particular, the resin T preferably contains an SP value of 16.5 MPa. 1 / 2 ~24.0MPa 1 / 2 If the resin T contains a structural unit derived from a polymerizable monomer with an SP value of 16.5 MPa 1 / 2 ~24.0MPa 1 / 2 If the structural unit of the polymerizable monomer is at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group and a hydrocarbon group having 12 or more carbon atoms is oriented on the surface of the ink film, the affinity with the laminate substrate is improved.

[0214] The SP value of the polymerizable monomer contained in the resin T is measured by the same method as the SP value of the polymerizable monomer A described above.

[0215] When the ink contains the resin T, the content of the resin T is preferably 1 to 10% by mass, more preferably 1.5 to 8% by mass, and even more preferably 2 to 6% by mass, based on the total amount of the ink.

[0216] (water)

[0217] The ink may contain small amounts of water.

[0218] Specifically, the water content is preferably 3% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less, relative to the total amount of the ink.

[0219] The ink is preferably a non-aqueous ink that does not substantially contain water.

[0220] (Colorant)

[0221] The ink preferably comprises at least one colorant.

[0222] The colorant is not particularly limited, and can be arbitrarily selected from known color materials such as pigments, water-soluble dyes, and disperse dyes. Among them, the colorant is preferably a pigment from the viewpoint of excellent weather resistance and rich color reproducibility.

[0223] The type of pigment is not particularly limited, and may be either an organic pigment or an inorganic pigment.

[0224] Examples of the pigment include pigments described in "Encyclopedia of Pigments" edited by Seishiro Ito (2000), "Industrial Organic Pigments" by W. Herbst, K. Hunger, Japanese Patent Publication No. 2002-12607, Japanese Patent Application Publication No. 2002-188025, Japanese Patent Application Publication No. 2003-26978, and Japanese Patent Application Publication No. 2003-342503.

[0225] When a pigment is used as a colorant in the ink, a dispersant may be contained as necessary.

[0226] Regarding colorants such as pigments and pigment dispersants, known documents such as JP-A-2011-225848, paragraphs 0152 to 0158, and JP-A-2009-209352, paragraphs 0132 to 0149, can be appropriately referred to.

[0227] When the ink contains a colorant, the content of the colorant is preferably 0.1% by mass to 20% by mass, and more preferably 0.5% by mass to 10% by mass, relative to the total amount of the ink.

[0228] (Other ingredients)

[0229] The ink may contain other ingredients than those mentioned above.

[0230] Examples of other components include ultraviolet absorbers, co-sensitizers, antioxidants, anti-fading agents, and conductive salts.

[0231] Regarding other components, known documents such as Japanese Patent Application Laid-Open No. 2011-225848 and Japanese Patent Application Laid-Open No. 2009-209352 can be referred to as appropriate.

[0232] (Physical properties of ink)

[0233] From the viewpoint of ejection properties, the viscosity of the ink is preferably 5 mPa·s to 50 mPa·s, more preferably 10 mPa·s to 30 mPa·s, and even more preferably 10 mPa·s to 25 mPa·s.

[0234] The viscosity is a value measured at 25°C.

[0235] The viscosity is a value measured using a viscometer, and can be measured using, for example, VISCOMETER RE-85L (manufactured by Toki Sangyo Co., Ltd.).

[0236] From the viewpoint of ejection properties, the surface tension of the ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and further preferably 25 mN / m to 45 mN / m.

[0237] The surface tension is a value measured at 25°C.

[0238] The surface tension is a value measured using a surface tensiometer, and can be measured using, for example, a product name “Automatic Surface Tentiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.)”.

[0239] <Method of applying ink>

[0240] The ink is applied by an inkjet recording method.

[0241] The ink ejection method in the inkjet recording method is not particularly limited and can be any of the known methods, for example, a charge control method that utilizes electrostatic induction force to eject ink, a drop-on-demand inkjet method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into a sound beam and irradiates the beam onto the ink to eject the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and utilizes the generated pressure.

[0242] As the inkjet recording method, the method described in Japanese Patent Publication No. 54-59936 can be particularly effectively used. In this inkjet recording method, the ink subjected to the action of thermal energy undergoes a rapid volume change, and the ink is ejected from the nozzle by the force generated by this state change. As the inkjet recording method, the method described in paragraphs 0093 to 0105 of Japanese Patent Publication No. 2003-306623 can also be used.

[0243] Inkjet recording is performed by ejecting ink from nozzles of an inkjet head to apply ink to an image recording substrate.

[0244] As inkjet head methods, there are a shuttle method that records while scanning a short serial head along the width direction of the recording medium; and a line method that uses a line head with recording elements arranged in the entire area corresponding to one side of the recording medium.

[0245] In the linear method, the image can be recorded on the entire surface of the recording medium by scanning the recording medium in a direction intersecting the arrangement direction of the recording elements. In the linear method, there is no need for a transport system such as a carriage for scanning a short-sized nozzle in the reciprocating method. In addition, in the linear method, compared with the reciprocating method, there is no need to move the carriage and perform complex scanning control of the recording medium, and only the recording medium moves. Therefore, according to the linear method, it is possible to achieve high-speed image recording compared with the reciprocating method.

[0246] The ink is preferably applied using an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and even more preferably 800 dpi or more). Dpi is an abbreviation for dots per inch, and 1 inch is 2.54 cm.

[0247] From the viewpoint of obtaining a high-definition image, the amount of ink droplets ejected from the nozzles of the inkjet head is preferably 1 pL (picoliter) to 10 pL, and more preferably 1.5 pL to 6 pL.

[0248] <Drying process>

[0249] The image recording step preferably includes a step of drying the applied ink after applying the ink to the image recording substrate (hereinafter also referred to as a "drying step").

[0250] The ink may be dried naturally, but is preferably dried by heating.

[0251] The heating temperature in heat drying is preferably 30°C to 90°C, more preferably 50°C to 80°C.

[0252] Examples of the heat drying method include infrared (IR) drying, warm air drying, and a method using a heating device (eg, a heater, a hot plate, a heating furnace, etc.).

[0253] Heat drying can be performed by heating the ink from at least one of the image recording surface side and the image non-recording surface side of the image recording substrate.

[0254] <Active Energy Ray Irradiation Step>

[0255] The image recording step preferably includes a step of irradiating the applied ink with active energy rays after applying the ink to the image recording substrate (hereinafter also referred to as “active energy ray irradiation step”).

[0256] By irradiating the ink applied to the image recording substrate with active energy rays, a polymerization reaction of the polymerizable compound contained in the ink proceeds, thereby fixing the image and improving the hardness of the image.

[0257] Examples of active energy rays include ultraviolet rays, visible rays, and electron beams. Among them, ultraviolet rays are preferred as active energy rays.

[0258] The peak wavelength of ultraviolet rays is preferably 200 nm to 405 nm, more preferably 220 nm to 390 nm, and further preferably 220 nm to 380 nm.

[0259] The exposure dose of ultraviolet light is preferably 20 mJ / cm 2 ~5J / cm 2 , more preferably 100 mJ / cm 2 ~1,500mJ / cm 2 The irradiation conditions and basic irradiation methods can be applied to the irradiation conditions and irradiation methods disclosed in Japanese Patent Publication No. 60-132767. Specifically, the irradiation method is preferably a method of providing light sources on both sides of a nozzle unit of an ink ejection device, scanning the nozzle unit and the light source in a so-called reciprocating manner, or a method of performing the irradiation by using other light sources that are not driven.

[0260] As the light source for ultraviolet irradiation, discharge lamps and laser light sources (gas lasers and solid lasers, etc.) are mainly used. As discharge lamps, for example, mercury lamps, metal halide lamps and ultraviolet fluorescent lamps are widely known. In addition, semiconductor light sources such as UV-LED (ultraviolet light emitting diode) and UV-LD (ultraviolet laser diode) are small, long-life, high-efficiency and low-cost, and are expected to be used as light sources for ultraviolet irradiation. Among them, the light source for ultraviolet irradiation is preferably a metal halide lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp or UV-LED.

[0261] <<Lamination process>>

[0262] The lamination step is a step of placing and laminating a lamination substrate containing a polymer containing vinyl chloride as a structural unit on the image recorded in the image recording step.

[0263] <Lamination Base Material>

[0264] Preferred embodiments of the laminating substrate are the same as those of the image recording substrate, and description thereof will be omitted.

[0265] <Lamination method>

[0266] In the lamination process, a laminating substrate is arranged on the image. At this time, other layers such as an adhesive layer can be arranged on the image, and the laminating substrate can be arranged across the other layers. However, in the manufacturing method of the laminate of the present invention, the ink film (i.e., image) obtained by curing the ink has excellent thermal softening properties, so it is preferred not to set other layers. That is, it is preferred to overlap and laminate in a manner that the image and the laminating substrate are in contact. Thus, a laminate having a laminated structure of image recording substrate / image / laminating substrate can be obtained.

[0267] In the lamination step, the image and the lamination substrate are preferably thermocompressed at a temperature of 100° C. or higher. The thermocompression bonding at a temperature of 100° C. or higher thermally fuses the image and the lamination substrate, thereby improving adhesion between the image and the lamination substrate.

[0268] From the viewpoint of suppressing thermal decomposition, the upper limit of the temperature during thermocompression bonding is preferably 200°C, more preferably 180°C.

[0269] The temperature during thermocompression bonding refers to the surface temperature of the lamination substrate.

[0270] The pressure during thermocompression bonding is preferably 0.1 MPa to 20 MPa, more preferably 0.5 MPa to 15 MPa.

[0271] The time for thermocompression bonding is, for example, 10 seconds to 500 seconds.

[0272] Thermocompression bonding may be performed in two stages. For example, the pressure in the first stage may be set to 0.5 MPa to 5 MPa, and the pressure in the second stage may be set to 6 MPa to 15 MPa, which is higher than the pressure in the first stage.

[0273] The laminate obtained by the method for producing a laminate of the present invention can be used as, for example, a floor material or a wall material for transportation equipment (railway, bus, etc.), or a floor material or a wall material for a building.

[0274] [Inkjet ink]

[0275] The inkjet ink of the present invention (hereinafter also simply referred to as "ink") contains a polymerizable monomer A having a cyclohexyl group, and the content of the polymerizable monomer A is 30% by mass or more based on the total amount of the inkjet ink.

[0276] The inkjet ink refers to an ink used when recording an image using an inkjet recording method.

[0277] Preferred embodiments of the ink of the present invention are the same as preferred embodiments of the ink used in the above-mentioned method for producing a laminate, and description thereof will be omitted.

[0278] The ink of the present invention has excellent solubility in a substrate containing a polymer containing vinyl chloride as a structural unit. Therefore, the ink of the present invention is preferably used for imparting to a substrate containing a polymer containing vinyl chloride as a structural unit. By using the ink on a substrate containing a polymer containing vinyl chloride as a structural unit, an image having excellent adhesion to the substrate can be recorded.

[0279] The ink of the present invention has excellent thermal softening properties of the ink film (i.e., image) formed by curing. Therefore, it is preferably used to arrange a laminating substrate on the image to produce a laminate. In particular, as the laminating substrate, it is preferred to use a substrate containing a polymer containing vinyl chloride as a structural unit.

[0280] [Image recording method]

[0281] The image recording method of the present invention preferably includes a step of recording an image by applying ink by an inkjet recording method on an image recording substrate containing a polymer containing vinyl chloride as a structural unit.

[0282] A preferred embodiment of the step of recording an image in the image recording method of the present invention is the same as a preferred embodiment of the image recording step in the method for producing a laminated body described above, and a description thereof will be omitted.

[0283] Example

[0284] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it departs from the gist of the present invention.

[0285] (Example 1 to Example 11, Comparative Example 1 to Comparative Example 3)

[0286] <Preparation of Cyan Pigment Dispersion>

[0287] The following components were mixed and stirred at 2,500 rpm for 10 minutes using a mixer (L4R manufactured by Silverson Co.) to obtain a mixture. The obtained mixture was then added to a bead mill disperser DIS PERMAT LS (manufactured by VMA Co.), and dispersed at 2,500 rpm for 6 hours using YTZ balls (manufactured by NIKKATO CORPORATION) having a diameter of 0.65 mm to obtain a cyan pigment dispersion.

[0288] · Cyan pigment: Product name "IRGALITE BLUE GLVO", manufactured by BASF Corporation ... 30% by mass

[0289] BYK-168: Product name: "DISPERSE BYK-168", manufactured by BYK Co., Ltd. ... 20% by mass

[0290] ·DVE-3: triethylene glycol divinyl ether, manufactured by BASF Corporation…50% by mass

[0291] <Preparation of ink>

[0292] The cyan pigment dispersion liquid and the components listed in Table 1 and Table 2 other than the components contained in the cyan pigment dispersion liquid were mixed in the amounts listed in Table 1 and Table 2 to prepare inks.

[0293] The details of the components other than the cyan pigment, the dispersant, and DVE-3 in Tables 1 and 2 are as follows.

[0294] (Polymerizable Monomer A)

[0295] ·4-tert-Butylcyclohexyl acrylate

[0296] ·3,3,5-Trimethylcyclohexyl acrylate

[0297] Cyclohexyl acrylate

[0298] Cyclohexyl methacrylate

[0299] ·1,4-Cyclohexanedimethanol monoacrylate

[0300] (N-vinyl compound)

[0301] NVC: N-vinyl caprolactam

[0302] ·Vmox: 5-methyl-3-vinyl-2-oxazolinone

[0303] (Other polymerizable compounds)

[0304] ·EOEOEA: Ethoxydiethylene glycol acrylate

[0305] CTFA: Cyclic trimethylolpropane formal acrylate

[0306] ·EOTMPTA: Trimethylolpropane ethylene oxide (EO) modified triacrylate

[0307] (Polymerization initiator)

[0308] ITX: 2-isopropylthioxanthone

[0309] Omni.819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omni rad 819", manufactured by IGM Resins BV)

[0310] Omni.TPO-H: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (product name "Omnirad TPO-H", manufactured by IGM Resins BV)

[0311] (Inhibitor)

[0312] ·TEMPOL:4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl

[0313] (Surfactant)

[0314] Tegorad2010: Product name "Tegorad2010", manufactured by Evonik Industries AG, molecular weight 800

[0315] <Manufacturing of Laminated Body>

[0316] -Image Recording Process-

[0317] As an image recording substrate, a polyvinyl chloride substrate (product name: "PVC 35phr", manufactured by OK AMOTO INDUSTRIES, INC.) was prepared.

[0318] A rubber heater (SR100 manufactured by THRE HIGH CO., LTD.) and an ultraviolet (UV) irradiation device (Vzero manufactured by Integration Technology) were installed on an inkjet printer (KEGON) manufactured by Afit Co., Ltd., and an inkjet printer modification machine was prepared. The output of the rubber heater was set to be able to heat the image recording substrate to which the ink was applied to about 60°C. The drying time of the ink during UV irradiation (i.e., the time from the ink ejected from the inkjet head landing on the image recording substrate to the UV irradiation) was adjusted to 10 seconds. The adjustment of the drying time of the ink at this time was carried out by adjusting the transmission speed (5m / min to 25m / min) and the timing of the UV shutter opening and closing.

[0319] The ink was ejected from the inkjet head of the modified inkjet printer to record a solid image on an image recording substrate to obtain an image recorded object. The resolution was set to 1200 dpi (dot per inch)×600 dpi.

[0320] -Lamination process 1-

[0321] As a lamination substrate, a polyvinyl chloride substrate (product name "SG800", manufactured by Keienu Trading Company Ltd., thickness 75 μm) was used.

[0322] A laminating substrate was arranged on the image recorded on the image recording substrate. The image and the laminating substrate were thermally pressed using a desktop automatic transfer press (product name "AF-54TEN", Asahi Garment Machinery Co., Ltd.). Thus, a laminate having a laminate structure of image recording substrate / image / laminating substrate was obtained.

[0323] The temperature during the thermocompression bonding was set to 130° C. The thermocompression bonding was performed at a pressure of 2 MPa for 300 seconds and then at a pressure of 10 MPa for 60 seconds.

[0324] The peel strength was measured using the evaluation sample of the laminate obtained in the lamination step 1. In addition, the surface state was evaluated using the image recorded material. The evaluation method is as follows.

[0325] [Peel strength]

[0326] Evaluation samples were prepared by the following method.

[0327] An image recorded sample of 3.2 cm×3.2 cm was cut out from the image recorded material obtained in the image recording step, and a laminating substrate sample of 3.2 cm×3.2 cm was cut out from the laminating substrate.

[0328] A PET (polyethylene terephthalate) sheet with a thickness of 12 μm was placed on the image recording surface of the image recording sample and in an area of ​​1.0 cm×3.2 cm including one side of the image recording sample. Next, a 3.2 cm×3.2 cm lamination substrate sample was overlapped on the entire area of ​​the image recording surface of the image recording sample and in the area where the PET sheet was placed (the area of ​​1.0 cm×3.2 cm) and the area where the PET sheet was not placed (the area of ​​2.2 cm×3.2 cm).

[0329] In this state, the image recording sample and the lamination substrate sample were laminated under the same conditions as in the above lamination step. The PET sheet was removed from the obtained laminate to obtain an evaluation sample.

[0330] In the evaluation sample, the image recording sample and the lamination base material sample were bonded in the region where the PET sheet was not arranged before the lamination process. On the other hand, in the evaluation sample, the image recording sample and the lamination base material sample were not bonded in the region where the PET sheet was arranged before the lamination process.

[0331] Next, in the area where the image recording sample and the laminating substrate sample are not bonded, a tensile test was performed in which the image recording sample and the laminating substrate sample were stretched in opposite directions, and the peel strength was measured. The tensile test was performed using a tensile testing machine (product name "Autograph AGS-X 5KN", manufactured by SHIMADZU CORPORATION). Two evaluation samples were prepared and the tensile test was performed twice. The average value of the two peel strengths was used. The evaluation criteria are as follows.

[0332] 5: Peel strength is 7 N / cm or more.

[0333] 4: The peel strength is 3 N / cm or more and less than 7 N / cm.

[0334] 3: The peel strength is 2 N / cm or more and less than 3 N / cm.

[0335] 2: The peel strength is 1 N / cm or more and less than 2 N / cm.

[0336] 1: The peel strength is 0.1 N / cm or more and less than 1 N / cm.

[0337] 0: Peel strength is less than 0.1 N / cm.

[0338] [Surface state]

[0339] The image recorded material obtained before the lamination step was stored at 40° C. for 24 hours.

[0340] After 24 hours, the image recording surface of the image recording material was wiped with a wiping paper (product name "KIMWIPE (registered trademark)", manufactured by NIPPO N PAPERCRECIA CO., LTD.). At this time, the stickiness of the image recording surface was confirmed. In addition, the traces of the image recording surface after wiping with the wiping paper were observed with the naked eye. The surface state was evaluated based on the stickiness and the presence or absence of scratches. The evaluation criteria are as follows.

[0341] A: No stickiness was felt on the surface, and no traces of wiping were visually recognized.

[0342] B: The stickiness of the surface is slightly felt, but no trace of wiping is visually recognized.

[0343] C: The stickiness of the surface is slightly felt, and traces of wiping are slightly visually recognized.

[0344] D: The stickiness of the surface is felt, and traces of wiping are slightly visually recognized.

[0345] E: The stickiness of the surface is felt, and the traces of wiping are visually recognized.

[0346] Tables 1 and 2 show the evaluation results.

[0347] In Table 1 and Table 2, molecular weights and glass transition temperatures (Tg) are described for polymerizable monomer A, N-vinyl compounds, and other polymerizable compounds.

[0348] In Table 1 and Table 2, "weighted average value of Tg" refers to the weighted average value of the glass transition temperatures when all polymerizable monomers contained in the ink are respectively regarded as homopolymers. "Polymerizable monomer A / N-vinyl compound" refers to the mass ratio of the content of polymerizable monomer A to the content of N-vinyl compound. "The proportion of polymerizable monomers having a molecular weight of 205 or less" refers to the proportion of polymerizable monomers having a molecular weight of 205 or less in all polymerizable compounds contained in the ink. "The proportion of monofunctional polymerizable compounds" refers to the proportion of monofunctional polymerizable compounds in all polymerizable compounds contained in the ink.

[0349] [Table 1]

[0350]

[0351] [Table 2]

[0352]

[0353] As shown in Tables 1 and 2, Examples 1 to 11 include a process of recording an image by applying ink by an inkjet recording method on a substrate containing a polymer containing vinyl chloride as a structural unit; and a process of arranging a laminated substrate containing a polymer containing vinyl chloride as a structural unit on the image and laminating it. The ink contains a polymerizable monomer A having a cyclohexyl group, and the content of the polymerizable monomer A is 20% by mass or more relative to the total amount of the ink. Therefore, it can be seen that the peel strength is high and the adhesion between the substrate and the image is excellent.

[0354] On the other hand, in Comparative Example 1, the ink does not contain polymerizable monomer A, and the adhesion between the substrate and the image is poor. In Comparative Example 2, the content of polymerizable monomer A contained in the ink is less than 20% by mass, and the adhesion between the substrate and the image is poor.

[0355] In Example 3, the content of the polymerizable monomer A is 40% by mass or more relative to the total amount of the ink, and it is found that the adhesion between the substrate and the image is excellent compared to Example 11.

[0356] In Example 3, the weighted average of the glass transition temperatures of all the polymerizable monomers contained in the ink as homopolymers was 100°C or less, and it was found that the adhesion between the substrate and the image was excellent compared with Example 8. In Example 3, the weighted average of the glass transition temperatures of all the polymerizable monomers contained in the ink as homopolymers was 0°C or more, and it was found that the adhesion between the substrate and the image was excellent and the stickiness of the surface was suppressed compared with Example 7.

[0357] In Example 3, the proportion of the polymerizable monomer having a molecular weight of 205 or less in all polymerizable compounds contained in the ink was 90 mass % or more, and it was found that the adhesion between the substrate and the image was excellent compared with Example 1.

[0358] In Example 3, the ratio of the monofunctional polymerizable compound to all polymerizable compounds contained in the ink was 90% by mass or more, and it was found that the adhesion between the substrate and the image was excellent compared to Example 9.

[0359] In Examples 2 to 4, the polymerizable monomer A includes at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, and cyclohexyl (meth)acrylate. It is found that the adhesion between the substrate and the image is excellent compared to Examples 1 and 10.

[0360] In Example 3, the ink contained an N-vinyl compound, and compared with Example 7, it was found that the adhesion between the substrate and the image was excellent and the stickiness of the surface was suppressed.

[0361] In Example 3, the mass ratio of the content of the polymerizable monomer A to the content of the N-vinyl compound is 0.4 or more, and it is found that the adhesion between the substrate and the image is excellent compared to Example 6.

[0362] In Example 3, the ink does not contain a surfactant, and it is found that the adhesion between the substrate and the image is excellent compared to Example 5.

[0363] [Example 101 to Example 105]

[0364] <Preparation of ink>

[0365] The cyan pigment dispersion liquid and the components listed in Table 4 other than the components contained in the cyan pigment dispersion liquid were mixed in the amounts listed in Table 4 to prepare inks.

[0366] The details of resins T1 to T4 in Table 3 are as follows: Resins T1 to T4 were synthesized by referring to the synthesis methods of Examples 8, 9, 25 and 19 of Japanese Patent No. 6861811. The weight average molecular weight of resins T1 to T4 was 10,000.

[0367] Table 3 shows the composition ratio (mass ratio) of the structural units constituting each resin and the SP value.

[0368] [Table 3]

[0369]

[0370] <Manufacturing of Laminated Body>

[0371] By the same image recording step as in Example 1, an image recorded material was obtained.

[0372] -Lamination process 2-

[0373] In the lamination step 2, the obtained image recorded material was used to obtain a laminated body under conditions different from those in the lamination step 1 described above.

[0374] Specifically, the temperature during the thermocompression bonding was set to 130° C., and the thermocompression bonding was performed at a pressure of 2 MPa for 300 seconds and then at a pressure of 4 MPa for 60 seconds.

[0375] The peel strength 2 was measured using the evaluation sample of the laminate obtained in the lamination step 2. The evaluation method was the same as the evaluation method for the evaluation sample of the laminate obtained in the lamination step 1.

[0376] Table 4 shows the evaluation results.

[0377] The ink used in Example 101 was the same as the ink used in Example 3, and only the lamination step in the production of the laminate was different.

[0378] [Table 4]

[0379]

[0380] In Examples 102 to 105, the ink contains a resin T containing at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms, and it is found that the peel strength is higher than that of Example 101.

[0381] In addition, regarding the invention of Japanese Patent Application No. 2022-162751 filed on October 7, 2022 and Japanese Patent Application No. 2023-108853 filed on June 30, 2023, the entirety of the invention is incorporated into this specification by reference. Furthermore, all documents, patent applications, and technical specifications described in this specification are incorporated into this specification by reference to the same extent as if each document, patent application, and technical specification was specifically and individually described and incorporated by reference.

Claims

1. A method for manufacturing a laminate, comprising: A step of recording an image by applying ink by an inkjet recording method on a substrate containing a polymer containing vinyl chloride as a structural unit; and a step of placing a laminating substrate containing a polymer including vinyl chloride as a structural unit on the image and laminating the image; The ink comprises a polymerizable monomer A having a cyclohexyl group, The content of the polymerizable monomer A is 20% by mass or more relative to the total amount of the ink.

2. The method for producing a laminate according to claim 1, wherein: The content of the polymerizable monomer A is 40% by mass or more relative to the total amount of the ink.

3. The method for producing a laminate according to claim 1 or 2, wherein: The weighted average value of the glass transition temperatures of all polymerizable monomers contained in the ink when they are respectively regarded as homopolymers is 0° C. to 100° C.

4. The method for producing a laminate according to claim 1 or 2, wherein: The polymerizable monomer having a molecular weight of 205 or less accounts for 90% by mass or more of all polymerizable compounds contained in the ink.

5. The method for producing a laminate according to claim 1 or 2, wherein: The ratio of the monofunctional polymerizable compound to all polymerizable compounds contained in the ink is 90% by mass or more.

6. The method for producing a laminate according to claim 1 or 2, wherein: The polymerizable monomer A includes at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate, and cyclohexyl(meth)acrylate.

7. The method for producing a laminate according to claim 1 or 2, wherein: The polymerizable monomer A includes cyclohexyl (meth)acrylate.

8. The method for producing a laminate according to claim 1 or 2, wherein: The ink also contains an N-vinyl compound.

9. The method for producing a laminate according to claim 8, wherein: The mass ratio of the content of the polymerizable monomer A to the content of the N-vinyl compound is 0.4 or more.

10. The method for producing a laminate according to claim 1 or 2, wherein: The ink further includes a resin T containing at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms.

11. The method for producing a laminate according to claim 10, wherein: The resin T contains a solubility parameter of 16.5 MPa. 1 / 2 ~24.0MPa 1 / 2 The structural unit of the polymerizable monomer.

12. The method for producing a laminate according to claim 1 or 2, wherein: The ink does not contain a surfactant, or the content of the surfactant is less than 0.1% by mass relative to the total amount of the ink.

13. The method for producing a laminate according to claim 1 or 2, wherein: In the lamination step, the image and the lamination substrate are overlapped and laminated so as to be in contact with each other.

14. An inkjet ink comprising a polymerizable monomer A having a cyclohexyl group, The content of the polymerizable monomer A is 30% by mass or more based on the total amount of the inkjet ink.

15. The inkjet ink according to claim 14, wherein The content of the polymerizable monomer A is 40% by mass or more based on the total amount of the inkjet ink.

16. The inkjet ink according to claim 14, wherein The weighted average value of the glass transition temperatures of all polymerizable monomers contained in the inkjet ink when they are respectively regarded as homopolymers is 0° C. to 100° C.

17. The inkjet ink according to claim 14, wherein: The polymerizable monomer having a molecular weight of 205 or less accounts for 90% by mass or more of all polymerizable compounds contained in the inkjet ink.

18. The inkjet ink according to claim 14, wherein: The ratio of the monofunctional polymerizable compound to all the polymerizable compounds contained in the inkjet ink is 90% by mass or more.

19. The inkjet ink according to claim 14, wherein: The polymerizable monomer A includes at least one selected from the group consisting of 3,3,5-trimethylcyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate, and cyclohexyl(meth)acrylate.

20. The inkjet ink according to claim 14, wherein The polymerizable monomer A includes cyclohexyl (meth)acrylate.

21. The inkjet ink according to claim 14, wherein: The inkjet ink further comprises an N-vinyl compound.

22. The inkjet ink according to claim 21, wherein The mass ratio of the content of the polymerizable monomer A to the content of the N-vinyl compound is 0.4 or more.

23. The inkjet ink according to claim 14, wherein: The inkjet ink further includes a resin T containing at least one group selected from the group consisting of a fluorinated hydrocarbon group, a polysiloxane group, and a hydrocarbon group having 12 or more carbon atoms.

24. The inkjet ink according to claim 23, wherein The resin T contains a solubility parameter of 16.5 MPa. 1 / 2 ~24.0MPa 1 / 2 The structural unit of the polymerizable monomer.

25. The inkjet ink according to claim 14, wherein: The inkjet ink does not contain a surfactant, or the content of the surfactant is less than 0.1% by mass relative to the total amount of the inkjet ink.

26. An image recording method comprising the step of recording an image by applying the inkjet ink according to any one of claims 14 to 25 to a substrate containing a polymer containing vinyl chloride as a structural unit by an inkjet recording method.

Images