WO2021095372A1 - Ink composition for ink-jet recording and method for recording image - Google Patents

Abstract

An ink composition for ink-jet recording which comprises a photochromic compound, one or more polymerizable compounds, and a polymerization initiator, wherein 70 mass% or more of the polymerizable compounds is accounted for by a polymerizable compound having a molecular weight of 600 or less; and a method for recording an image.

Description

Ink composition for inkjet recording and image recording method

The present disclosure relates to an ink composition for inkjet recording and an image recording method.

The photochromic compound has the property of being colored when irradiated with ultraviolet rays and then returning to colorless when irradiated with visible light. Inks containing such photochromic compounds are expected to be used for security purposes by recording code images on packaging of foods, cosmetics, and the like.

As an ink containing a photochromic compound, for example, Japanese Patent Application Laid-Open No. 2013-24109 contains a photochromic material and a plurality of curable compounds, and has a capacity average Hansen fractionation dispersion force parameter of about 0.4 to about 0.62. Ink compositions having a volume average Hansen fractionation polarity parameter from about 0.1 to about 0.3 and a volume average Hansen fraction hydrogen bond parameter from about 0.2 to about 0.4 are described. In Japanese Patent Application Laid-Open No. 2010-520828, a) 30 to 80% by mass of monofunctional LCP's, f) 0.01 to 10% by mass of an initiator, and h) 0.01 to 50% by mass of an additive. Mixtures containing are described, and photochromic pigments or dyes are described as additives. Japanese Patent Application Laid-Open No. 2006-231910 contains an infrared absorber, a radical polymerization initiator, an acid generator, a binder polymer having an ethylenically unsaturated group, a polymerizable monomer, a photochromic compound, a fluorine-based surfactant, and a solvent. The liquid is listed. Japanese Unexamined Patent Publication No. 2011-132265 describes a security ink containing a specific photochromic compound and a supporting material containing a resin.

However, the compositions described in JP-A-2013-24109, JP-A-2010-520828, and JP-A-2006-231910 all contain oligomers or polymers, and are images obtained by an inkjet recording method. No record is expected. Further, in Japanese Patent Application Laid-Open No. 2011-132265, the readability is not examined.

The present disclosure has been made in view of such circumstances, and the problem to be solved by the embodiment of the present invention is excellent invisibility, readable by ultraviolet irradiation, and a predetermined time after ultraviolet irradiation. It is an object of the present invention to provide an ink composition for inkjet recording and an image recording method capable of recording an image having excellent invisibility after the lapse of time.

Specific means for solving the above problems include the following aspects.
<1> An ink composition for inkjet recording, which comprises a photochromic compound, a polymerizable compound, and a polymerization initiator, and is a polymerizable compound having a molecular weight of 600 or less in an amount of 70% by mass or more based on the total mass of the polymerizable compound.
<2> The ink composition for inkjet recording according to <1>, wherein the photochromic compound is at least one selected from the group consisting of a spiropyran compound, a spirooxazine compound, a naphthopirane compound and a diarylethene compound.
<3> The ink composition for inkjet recording according to <1> or <2>, wherein 60% by mass or more is a polyfunctional polymerizable monomer with respect to the total mass of the polymerizable compound.
<4> The ink composition for inkjet recording according to any one of <1> to <3>, which further contains a sensitizer having a molecular weight of 1000 or more.
<5> The ink composition for inkjet recording according to <4>, wherein the sensitizer is a thioxanthone-based compound.
<6> The ink composition for inkjet recording according to any one of <1> to <5>, wherein at least one of the polymerizable compounds is a polymerizable compound containing an ethylene oxide chain.
<7> The ink composition for inkjet recording according to any one of <1> to <6>, wherein the polymerization initiator is an acylphosphine oxide-based polymerization initiator.
<8> An image recording method for recording a code image on a substrate by an inkjet recording method using the ink composition for inkjet recording according to any one of <1> to <7>.
<9> The image recording method according to <8>, wherein the code image is a barcode, QR code (registered trademark) or dot code.
<10> Using the inkjet recording ink composition according to any one of <1> to <7>, a step of recording an image for alignment on a substrate by an inkjet recording method, and active energy. An image recording method including a step of irradiating a line.

According to the present disclosure, there are provided an ink composition for inkjet recording and an image recording method capable of recording an image having excellent invisibility, being readable by ultraviolet irradiation, and having excellent invisibility after a lapse of a predetermined time after being irradiated with ultraviolet rays. can do.

Hereinafter, the ink composition for inkjet recording and the image recording method of the present disclosure will be described in detail.

The numerical range indicated by using "-" in the present specification means a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

In the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means.
In the present specification, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present specification, the term "process" is included in this term as long as the intended purpose of the process is achieved, not only in an independent process but also in the case where it cannot be clearly distinguished from other processes. Is done.
In the present specification, "(meth) acrylic" is a term used in a concept that includes both acrylic and methacrylic, and "(meth) acrylate" is a term that is used as a concept that includes both acrylate and methacrylate. Is.

[Ink composition for inkjet recording]
The ink composition of the present disclosure contains a photochromic compound, a polymerizable compound, and a polymerization initiator, and is a polymerizable compound having a molecular weight of 600 or less in an amount of 70% by mass or more based on the total mass of the polymerizable compound. The ink composition of the present disclosure is for inkjet recording. That is, the ink composition of the present disclosure is an ink composition mounted on an inkjet recording device and applied by an inkjet recording method.

For example, Japanese Patent Application Laid-Open No. 2013-241009, Japanese Patent Application Laid-Open No. 2010-520828, and Japanese Patent Application Laid-Open No. 2006-231910 contain a composition containing an oligomer having a polymerizable group or a polymer having a polymerizable group together with a photochromic compound. The thing is listed. Since the compositions described in these patent documents contain an oligomer having a polymerizable group or a polymer having a polymerizable group, they have a high viscosity and are not expected to be image-recorded by an inkjet recording method. Further, it is considered that an image formed of an oligomer having a polymerizable group or a composition containing a polymer having a polymerizable group takes a long time to disappear after being colored by ultraviolet irradiation.

On the other hand, the ink composition of the present disclosure contains a photochromic compound, a polymerizable compound, and a polymerization initiator, and is a polymerizable compound having a molecular weight of 600 or less in an amount of 70% by mass or more based on the total mass of the polymerizable compound. Therefore, it is possible to record an image having excellent invisibility, being readable by ultraviolet irradiation, and having excellent invisibility after a lapse of a predetermined time after being irradiated with ultraviolet rays.

Hereinafter, each component contained in the ink composition of the present disclosure will be described.

<Photochromic compound>
The ink composition of the present disclosure contains a photochromic compound. A photochromic compound is a compound in which the chemical bond state is changed by the action of light to reversibly generate two isomers. The two isomers have different absorption spectra from each other. The photochromic compound has, for example, a property of being colored when irradiated with ultraviolet rays and then returning to colorless when irradiated with visible light. The photochromic compound may be used alone or in combination of two or more.

The photochromic compounds include a light-opening ring-type compound that changes from a ring-opening body to a ring-opening body or a ring-opening body to a ring-opening body by the action of light, and a photogeometric isomerization type compound that changes from a trans body to a cis body. And. Among them, from the viewpoint of repeatability, as the photochromic compound, a compound that changes from a ring-opening body to a ring-opening body or from a ring-opening body to a ring-opening body by the action of light, that is, a photochromic compound having a ring-opening ring type is preferable.

Examples of the photoopen / close ring type photochromic compound include a spiro compound, a naphthopylan compound, a diarylethene compound, a flugide compound, and a flugimid compound. Examples of the spiro-based compound include a spiropyran-based compound, a spirothiopyran-based compound, and a spirooxazine-based compound. In the present disclosure, from the viewpoint of thermal stability, the photochromic compound is preferably at least one selected from the group consisting of spiropyran compounds, spirooxazine compounds, naphthopylane compounds and diarylethene compounds.

In the present disclosure, the "system compound" means a compound having a skeleton or structure in the molecule with the name "system compound". For example, "spiro-based compound" means a compound having a spiro skeleton.

(Spiro compound)
The spiro compound is represented by, for example, the following formula (1).

In formula (1), X represents NR ¹ , O or S. R ¹ represents an aliphatic group or an aromatic group. Aliphatic and aromatic groups may have substituents.

Examples of the aliphatic group include an alkyl group, an alkenyl group, an alkynyl group and an aralkyl group. The aliphatic group may have a substituent. Substituents include halogen atoms (eg, fluorine atom, chlorine atom, bromine atom and iodine atom), cyano group, nitro group, aryl group, heterocyclic group, -OR ¹⁰ , -COR ¹¹ , -COOR ¹² , -OCOR. ¹³ , -NR ¹⁴ R ¹⁵ , -NHCOR ¹⁶ , -CONR ¹⁷ R ¹⁸ , -NHCONR ¹⁹ R ²⁰ , -NHCOOR ²¹ , -SR ²² , -SO ₂ R ²³ , -SO ₂ OR ²⁴ , -NHSO ₂ R ²⁵ and SO ₂ NR ²⁶ R ²⁷ can be mentioned. R ¹⁰ to R ²⁷ are independently hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, respectively. It represents an aryl group having 6 to 19 carbon atoms or a heterocyclic group.

The alkyl group may be cyclic or chain-like. The chain alkyl group may be a linear alkyl group or a branched chain alkyl group. The number of carbon atoms of the alkyl group is preferably 1 to 20, more preferably 1 to 12, and even more preferably 1 to 8. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a t-butyl group, a cyclopropyl group, a cyclohexyl group and a 2-ethylhexyl group. Examples of the alkyl group having a substituent include a 2-hydroxyethyl group, a 2-carboxyethyl group, a 2-methoxyethyl group, a 2-diethylaminoethyl group, a 2-sulfoethyl group, a 3-sulfopropyl group, a 3-sulfobutyl group and 4 -Sulfobutyl groups can be mentioned.

The alkenyl group may be cyclic or chain. The chain alkenyl group may be a linear alkenyl group or a branched chain alkenyl group. The alkenyl group preferably has 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and even more preferably 2 to 8 carbon atoms. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-propenyl group, a 2-butenyl group, a 2-pentenyl group and a 2-hexenyl group.

The alkynyl group may be cyclic or chain-like. The chain alkynyl group may be a linear alkynyl group or a branched chain alkynyl group. The alkynyl group preferably has 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and even more preferably 2 to 8 carbon atoms. Examples of the alkynyl group include an ethynyl group and a 2-propynyl group.

The alkyl moiety of the aralkyl group is the same as the above alkyl group. The aryl moiety of the aralkyl group is the same as that of the aryl group described later. Examples of the aralkyl group include a benzyl group and a phenethyl group.

Examples of the aromatic group include an aryl group. The aromatic group may have a substituent. Examples of the substituent include the substituents that the above-mentioned aliphatic group may have.

The aryl group preferably has 6 to 25 carbon atoms, more preferably 6 to 15 carbon atoms, and most preferably 6 to 10 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the aryl group having a substituent include a 4-carboxyphenyl group, a 4-acetamidophenyl group, a 3-methanesulfonamidephenyl group, a 4-methoxyphenyl group, a 3-carboxyphenyl group, and a 3,5-dicarboxyphenyl group. Examples thereof include 4-methanesulfonamidephenyl group and 4-butanesulfonamidephenyl group.

The heterocyclic group may have a substituent. Examples of the substituent include the substituents that the above-mentioned aliphatic group may have, and the preferred range is also the same.

The heterocycle of the heterocyclic group is preferably a 5-membered ring or a 6-membered ring. The heterocycle may be a monocyclic ring or a condensed ring. Heterocycles include pyridine ring, piperidine ring, furan ring group, furfuran ring, thiophene ring, pyrrole ring, quinoline ring, morpholine ring, indole ring, imidazole ring, pyrazole ring, carbazole ring, phenothiazine ring, phenoxazine ring, and indole ring. Examples thereof include a ring, a thiazole ring, a pyrazine ring, a thiaziazine ring, a benzoquinoline ring and a thiazizole ring.

X is preferably ^{NR 1.}

In formula (1), Q represents O, S or CR ² R ³ . R ² and R ³ independently represent an aliphatic group or an aromatic group, respectively. Examples of the aliphatic group and the aromatic group include those described above, and the preferred range is also the same. R ² and R ³ may be bonded to each other to form a ring.

When R ² and R ³ are bonded to each other to form a ring, the ring structure is a 5- or 6-membered monocyclic structure; and two or more 5- or 6-membered monocyclic structures are combined. Polycyclic structure;

Examples of the 5-membered or 6-membered monocyclic structure include an aliphatic ring, an aromatic ring, and a heterocycle. Heteroatoms in the hetero ring include N, O, and S.

Q is preferably ^{CR 2} R ^3.

In formula (1), Y represents N, O or S. Y is preferably O.

In formula (1), Z represents CH, N or P. Z is preferably CH or N.

In formula (1), A represents a group of atoms constituting a ring formed by bonding with Q and X.

Examples of the ring structure formed by A, Q and X include a 5-membered or 6-membered monocyclic structure; and a polycyclic structure in which two or more 5-membered or 6-membered monocyclic structures are combined. A two-ring structure is preferred.

Examples of the 5-membered or 6-membered monocyclic structure include an aliphatic ring, an aromatic ring, and a heterocycle. Heteroatoms in the hetero ring include N, O, and S. The combination of monocyclic rings in the bicyclic structure includes a combination of an aliphatic ring and an aliphatic ring, a combination of an aliphatic ring and an aromatic ring, a combination of an aliphatic ring and a heterocycle, and an aromatic ring and an aromatic ring. The combination with, the combination of the aromatic ring and the hetero ring, and the combination of the hetero ring and the hetero ring can be mentioned. Among them, as the ring formed by A, Q and X, two rings composed of an aromatic ring and a hetero ring are preferable, and an indole ring is more preferable.

In formula (1), V ¹ represents a substituent attached to the ring formed by A, Q and X. Examples of V ¹ include a hydrogen atom, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom), a cyano group, a nitro group, an alkyl group having 1 to 20 carbon atoms, and an alkenyl group having 2 to 20 carbon atoms. Alkinyl group with 2 to 20 carbon atoms, aralkyl group with 7 to 20 carbon atoms, aryl group with 6 to 19 carbon atoms, heterocyclic group, -OR ¹⁰ , -COR ¹¹ , -COOR ¹² , -OCOR ¹³ , -NR ¹⁴ R ¹⁵ , -NHCOR ¹⁶ , -CONR ¹⁷ R ¹⁸ , -NHCONR ¹⁹ R ²⁰ , -NHCOOR ²¹ , -SR ²² , -SO ₂ R ²³ , -SO ₂ OR ²⁴ , -NHSO ₂ R ²⁵ or SO ₂ NR ²⁶ R ²⁷ can be mentioned. R ¹⁰ to R ²⁷ are independently hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, respectively. It represents an aryl group having 6 to 19 carbon atoms or a heterocyclic group. Examples of the alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group include those described above.

In equation (1), m1 represents an integer from 0 to 4.

In formula (1), R ⁴ and R ⁵ are independently hydrogen atom, halogen atom (for example, fluorine atom, chlorine atom, bromine atom and iodine atom), cyano group, nitro group and alkyl having 1 to 20 carbon atoms. Group, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aralkyl group with 7 to 20 carbon atoms, aryl group with 6 to 19 carbon atoms, heterocyclic group, -OR ¹⁰ , -COR ¹¹ , -COOR ¹² , -OCOR ¹³ , -NR ¹⁴ R ¹⁵ , -NHCOR ¹⁶ , -CONR ¹⁷ R ¹⁸ , -NHCONR ¹⁹ R ²⁰ , -NHCOOR ²¹ , -SR ²² , -SO ₂ R ²³ , -SO ₂ OR ²⁴ , -Represents NHSO ₂ R ²⁵ or SO ₂ NR ²⁶ R ²⁷ . R ¹⁰ to R ²⁷ are independently hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, respectively. It represents an aryl group having 6 to 19 carbon atoms or a heterocyclic group. R ⁴ and R ⁵ may be bonded to each other to form a ring having 3 to 20 carbon atoms. Examples of the alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group include those described above.

When R ⁴ and R ⁵ are bonded to each other to form a ring, the ring structure is a combination of two or more 5-membered or 6-membered monocyclic structures; and two or more 5-membered or 6-membered monocyclic structures. Polycyclic structure; The ^{ring formed by bonding R 4} and R ⁵ to each other is preferably an aromatic hydrocarbon ring, more preferably a benzene ring or a naphthalene ring.

In the formula (1), the ring formed by A, Q and X is more preferably an indole ring, and R ⁴ and R ⁵ are bonded to each other to form a ring having 3 to 20 carbon atoms. Is preferable. Specifically, the spiro compound is preferably represented by the following formula (1A).

In the formula (1A), Y, Z, R ¹ , V ¹ and m 1 are the same as those in the formula (1).

In formula (1A), B represents a group of atoms required to form an aromatic hydrocarbon ring. Examples of the aromatic hydrocarbon ring include a benzene ring and a naphthalene ring.

In formula (1A), V ² represents a substituent attached to the ring formed by B. Examples of V ² include a hydrogen atom, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom), a cyano group, a nitro group, an alkyl group having 1 to 20 carbon atoms, and an alkenyl group having 2 to 20 carbon atoms. Alkinyl group with 2 to 20 carbon atoms, aralkyl group with 7 to 20 carbon atoms, aryl group with 6 to 19 carbon atoms, heterocyclic group, -OR ¹⁰ , -COR ¹¹ , -COOR ¹² , -OCOR ¹³ , -NR ¹⁴ R ¹⁵ , -NHCOR ¹⁶ , -CONR ¹⁷ R ¹⁸ , -NHCONR ¹⁹ R ²⁰ , -NHCOOR ²¹ , -SR ²² , -SO ₂ R ²³ , -SO ₂ OR ²⁴ , -NHSO ₂ R ²⁵ or SO ₂ NR ²⁶ R Represents ^27. R ¹⁰ to R ²⁷ are independently hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, respectively. It represents an aryl group having 6 to 19 carbon atoms or a heterocyclic group. Preferred embodiments of the alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group are the same as the preferred embodiments described above.

In formula (1A), m2 represents an integer from 0 to 4.

In the formula (1), the compound in which Y is O and Z is CH is a spiropyran compound. Examples of the spiropyran-based compound include 1,3,3-trimethylindolino-8'-methoxybenzopyrrilospiran, 1,3,3-trimethylindolino-6'-nitrobenzopyrrilospiran, 1,3. 3-trimethylindolino-6'-nitro-8'-methoxybenzopyrrilopyran, 1,3,3-trimethylindolino-5-methoxy-6'-nitrobenzopyrrilopyran, 1,3,3-trimethyl Spirobenzo such as indolino-6'-bromo-8'-nitrobenzopyrrilopyran, 1,3,3-trimethylindolinobenzopyrrilopyran, spiro [2H-1-benzopyran-2,2'-indoline] Pyran compounds; and 1,3,3-trimethylindolino-7'-nitronaphthpyrrilospiran, 1,3,3-trimethylindolino-8'-nitronaphthpyrrilospiran, 1,3,3-trimethyl Examples thereof include spironaftpyran-based compounds such as indolinonaphthopyriropyran and spirindolinonaphthopyran.

In the formula (1), the compound in which Y is S and Z is CH is a spirothiopyran-based compound. Examples of the spirothiopyran compound include 1,3,3-trimethylindolinobenzospirothiopyran.

In the formula (1), the compound in which Y is O and Z is N is a spirooxazine-based compound. Examples of the spiroxazine-based compound include 1,3,3-trimethylspiro [2H-indole-2,3'-[3H] pyrido [4,3-f] [1,4] benzoxazine] and 4-fluoro. -1,3,3-trimethylspiro [2H-indole-2,3'-[3H] pyridos [4,3-f] [1,4] benzoxazines], 5-fluoro-1,3,3-trimethyl Spiro [2H-indole-2,3'-[3H] pyrido [4,3-f] [1,4] benzoxazine], 6-fluoro-1,3,3-trimethylspiro [2H-indole-2, 3'-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-chloro-1,3,3-trimethylspiro [2H-indole-2,3'-[3H] pyrido [ 4,3-f] [1,4] benzoxazine], 5-bromo-1,3,3-trimethylspiro [2H-indole-2,3'-[3H] pyrido [4,3-f] [1 , 4] Benzoxazine], 1'-methyldispyro [cyclohexane-1,3'-[3H] indol-2'(1'H), 3 "-[3H] pyrido [4,3-f] [1,4] ] Benzoxazine], 4-fluoro-1'-methyldispyro [cyclohexane-1,3'-[3H] indol-2'(1'H), 3 "-[3H] pyrido [4,3-f] [1 , 4] Benzoxazine], 5-Fluoro-1'-methyldispyro [cyclohexane-1,3'-[3H] indol-2'(1'H), 3 "-[3H] pyrido [4,3-f] [1,4] benzoxazines], 6-fluoro-1'-methyldispyro [cyclohexane-1,3'-[3H] indol-2'(1'H), 3 "-[3H] pyridoes [4,3-] f] [1,4] benzoxazine], 5-chloro-1'-methyldispyro [cyclohexane-1,3'-[3H] indol-2'(1'H), 3 "-[3H] pyrido [4, 3-f] [1,4] benzoxazine], 5-bromo-1'-methyldispyro [cyclohexane-1,3'-[3H] indol-2'(1'H), 3 "-[3H] pyrido [ Spirobenzoxazines such as 4,3-f] [1,4] benzoxazines; and 1,3,3-trimethylspiro [Indolino-2,3'-[3H] naphtho [2,1-b] [1,4] Oxazine], 5-methoxy-1,3,3-trimethylspiro [Indolino-2,3'-[3H] Naft [2,1-b] [1, 4] Oxazine], 5-Chlor-1,3,3-trimethylspiro [Indolino-2,3'-[3H] Naft [2,1-b] [1,4] Oxazine], 4,7-diethoxy- 1,3,3-trimethylspiro [Indolino-2,3'-[3H] naphtho [2,1-b] [1,4] oxazine], 5-chloro-1-butyl-3,3-dimethylspiro [ Indolino-2,3'-[3H] Naft [2,1-b] [1,4] Oxazine], 1,3,3,5-Tetramethyl-9'-ethoxyspiro [Indolino-2,3'- [3H] Naft [2,1-b] [1,4] Oxazine], 1-benzyl-3,3-dimethylspiro [Indolin-2,3'-[3H] Naft [2,1-b] [1 , 4] Oxazines], 1- (4-methoxybenzyl) -3,3-dimethylspiro [Indolin-2,3'-[3H] naphtho [2,1-b] [1,4] oxazines], 1- (2-Methylbenzyl) -3,3-dimethylspiro [Indolin-2,3'-[3H] naphtho [2,1-b] [1,4] oxazines], 1- (3,5-dimethylbenzyl) -3,3-Dimethylspiro [Indolin-2,3'-[3H] Naft [2,1-b] [1,4] Oxazine], 1- (4-chlorobenzyl) -3,3-dimethylspiro [ Indolin-2,3'-[3H] Naft [2,1-b] [1,4] Oxazine], 1- (4-Bromobenzyl) -3,3-dimethylspiro [Indolin-2,3'-[ 3H] Naft [2,1-b] [1,4] Oxazine], 1- (2-fluorobenzyl) -3,3-dimethylspiro [Indolin-2,3'-[3H] Naft [2,1-] b] [1,4] Oxazine], 6'-(2,3-dihydro-1H-indole-1-yl) -1,3-dihydro-3,3-dimethyl-1-propyl-spiro [2H-indole] -2,3'-[3H] -naphtho [2,1-b] [1,4] oxazine], 6'-(2,3-dihydro-1H-indol-1-yl) -1,3-dihydro -3,3-dimethyl-1- (2-methylpropyl) -spiro [2H-indole-2,3'-[3H] -naphtho [2,1-b] [1,4] oxazines], 1,3 , 3-trimethyl-1-6'-(2,3-dihydro-1H-indol-1-yl) -spiro [2H-indole-2,3'-[3H] -naphtho [2,1-b] [ 1,4] Oxazine], 1,3,3-trimethyl-6'-(1-) Piperidil) -spiro [2H-indole-2,3'-[3H] -naphtho [2,1-b] [1,4] oxazine], 1,3,3-trimethyl-6'-(1-piperidyl) -6- (trifluoromethyl) -spiro [2H-indole-2,3'-[3H] -naphtho [2,1-b] [1,4] oxazine], 1,3,3,5,6- Pentamethyl-spiro [2H-indole-2,3'-[3H] -naphtho [2,1-b] [1,4] oxazine], 1,3-dihydro-1,3,3-trimethylspiro [2H- Examples thereof include spironaphthooxazine-based compounds such as Indol-2,3'-[3H] naphtho [2,1-b]-[1,4] oxazine].

(Naftpyran compound)
The naphthopirane compound is represented by, for example, the following formula (2A) or formula (2B).

In formulas (2A) and (2B), V ³ represents a substituent attached to the naphthalene ring, and R ³⁰ , R ³¹ , R ³² and R ³³ represent a substituent bound to the pyran ring.

In formulas (2A) and (2B), R ³⁰ , R ³¹ , R ³² , R ³³ and V ³ independently represent a hydrogen atom, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom), respectively. ), Cyan group, nitro group, alkyl group having 1 to 20 carbon atoms, alkenyl group having 2 to 20 carbon atoms, alkynyl group having 2 to 20 carbon atoms, aralkyl group having 7 to 20 carbon atoms, 6 to 19 carbon atoms. Aryl group, heterocyclic group, -OR ¹⁰ , -COR ¹¹ , -COOR ¹² , -OCOR ¹³ , -NR ¹⁴ R ¹⁵ , -NHCOR ¹⁶ , -CONR ¹⁷ R ¹⁸ , -NHCONR ¹⁹ R ²⁰ , -NHCOOR ²¹ ,- Represents SR ²² , -SO ₂ R ²³ , -SO ₂ OR ²⁴ , -NHSO ₂ R ²⁵ or SO ₂ NR ²⁶ R ^27. R ¹⁰ to R ²⁷ are independently hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, respectively. It represents an aryl group having 6 to 19 carbon atoms or a heterocyclic group. Examples of the alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group include those described above. The alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group may have a substituent.

In the formula (2A) and the formula (2B), m3 represents an integer of 0 to 6.

Examples of the naphthopyran compound include 3,3-diphenyl-3H-naphtho [2,1-b] pyran.

(Diarylethene compound)
The diarylethene compound is represented by, for example, the following formula (3).

In formula (3), Z ¹ and Z ² independently ^{represent NR 48} , O or S, respectively. R ⁴⁸ represents an aliphatic group or an aromatic group. Aliphatic and aromatic groups may have substituents. Preferred embodiments of the aliphatic group and the aromatic group are the same as the preferred embodiments described above. Moreover, the preferred embodiment of the substituent is the same as the preferred embodiment described above.

It is preferable that Z ¹ and Z ² are S independently of each other.

In formula (3), R ⁴⁰ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ , R ⁴⁶ and R ⁴⁷ are independently hydrogen atom and halogen atom (for example, fluorine atom, chlorine atom and bromine atom), respectively. And iodine atom), cyano group, nitro group, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aralkyl group with 7 to 20 carbon atoms, 6 carbon atoms. ~ 19 aryl groups, heterocyclic groups, -OR ¹⁰ , -COR ¹¹ , -COOR ¹² , -OCOR ¹³ , -NR ¹⁴ R ¹⁵ , -NHCOR ¹⁶ , -CONR ¹⁷ R ¹⁸ , -NHCONR ¹⁹ R ²⁰ , -NHCOOR Represents ²¹ , -SR ²² , -SO ₂ R ²³ , -SO ₂ OR ²⁴ , -NHSO ₂ R ²⁵ or SO ₂ NR ²⁶ R ^27. R ¹⁰ to R ²⁷ are independently hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, respectively. It represents an aryl group having 6 to 19 carbon atoms or a heterocyclic group. Examples of the alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group include those described above. The alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group and heterocyclic group may have a substituent.

R ⁴¹ and R ⁴² , R ⁴³ and R ⁴⁴ , and R ⁴⁵ and R ⁴⁶ may be bonded to each other to form a ring having 3 to 20 carbon atoms. When R ⁴¹ and R ⁴² , and R ⁴⁵ and R ⁴⁶ are bonded to each other to form a ring, the ring structure is a 5-membered or 6-membered monocyclic structure; and a 5-membered or 6-membered monocyclic structure. A polycyclic structure in which two or more ring structures are combined;

R ⁴⁰ and R ⁴⁷ are each independently preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably a methyl group.

In R ⁴¹ , R ⁴² , R ⁴⁵ and R ⁴⁶ , R ⁴¹ and R ⁴² , and R ⁴⁵ and R ⁴⁶ are bonded to each other to form a ring having 3 to 20 carbon atoms, or they are independent of each other. , A hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 19 carbon atoms is preferable. The ^{ring formed by bonding R 41} and R ⁴² and R ⁴⁵ and R ⁴⁶ to each other is more preferably a benzene ring or a cyclohexane ring. Further, ^{it is more preferable that R 41} , R ⁴² , R ⁴⁵ and R ⁴⁶ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

It is preferable that R ⁴³ and R ⁴⁴ are bonded to each other to form a ring represented by any of the following structures.

Examples of the diarylethene compound include 2,3-bis (2,4,5-trimethyl-3-thienyl) maleic anhydride and 2,3-bis (2,4,5-trimethyl-3-thienyl) maleimide. , Cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-thienyl) ethene, 1,2-bis [2-methylbenzo [b] thiophene-3-yl] -3, 3,4,4,5,5-hexafluoro-1-cyclopentene and 1,2-bis (2,4-dimethyl-5-phenyl-3-thienyl) -3,3,4,5,4,5- Hexafluoro-1-cyclopentene can be mentioned. Further, examples of the diarylethene compound include the following compounds.

The content of the photochromic compound in the ink composition is preferably 0.1% by mass to 5% by mass, more preferably 0.5% by mass to 3% by mass, based on the total mass of the ink composition.

<Polymerizable compound>
The ink composition of the present disclosure contains a polymerizable compound. The polymerizable compound is a compound having a polymerizable group. The polymerizable compound is preferably a compound in which the polymerization reaction proceeds to become a polymer by the action of radicals generated from a radical polymerization initiator described later, that is, a radical polymerizable compound. The polymerizable compound may be used alone or in combination of two or more.

In the present disclosure, 70% by mass or more of the total mass of the polymerizable compound is a polymerizable compound having a molecular weight of 600 or less. The content of the polymerizable compound having a molecular weight of 600 or less is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the polymerizable compound. The upper limit of the content of the polymerizable compound having a molecular weight of 600 or less is not particularly limited. 100% by mass with respect to the total mass of the polymerizable compound may be a polymerizable compound having a molecular weight of 600 or less. When 70% by mass or more of the polymerizable compound with respect to the total mass of the polymerizable compound is a polymerizable compound having a molecular weight of 600 or less, the viscosity of the ink composition does not become too high, and it is suitable for image recording by an inkjet recording method. Further, when 70% by mass or more of the polymerizable compound with respect to the total mass of the polymerizable compound is a polymerizable compound having a molecular weight of 600 or less, the invisibility is excellent, the compound can be read by ultraviolet irradiation, and a predetermined time elapses after ultraviolet irradiation. Later, an image having excellent invisibility can be recorded.

The polymerizable compound includes a monofunctional polymerizable monomer having one polymerizable group and a polyfunctional polymerizable monomer having two or more polymerizable groups. In the present disclosure, from the viewpoint of improving the scratch resistance of the image, it is preferable that 60% by mass or more is the polyfunctional polymerizable monomer with respect to the total mass of the polymerizable compound. The content of the polyfunctional polymerizable monomer is preferably 75% by mass or more, more preferably 90% by mass or more, based on the total mass of the polymerizable compound. The upper limit of the content of the polyfunctional polymerizable monomer is not particularly limited. 100% by mass with respect to the total mass of the polymerizable compound may be a polyfunctional polymerizable monomer. When 60% by mass or more is a polyfunctional polymerizable monomer with respect to the total mass of the polymerizable compound, the crosslink density is increased and the scratch resistance of the image is improved. Further, when 60% by mass or more of the total mass of the polymerizable compound is a polyfunctional polymerizable monomer, unreacted polymerizable monomer is unlikely to remain after the completion of the polymerization reaction. For example, when the base material is a food packaging material or a cosmetic packaging material, it is preferable because the transfer of the unreacted polymerizable monomer to the food or cosmetic is suppressed.

The polyfunctional polymerizable monomer may be a bifunctional polymerizable monomer or a trifunctional or higher functional polymerizable monomer, but from the viewpoint of appropriately adjusting the viscosity of the ink composition, the bifunctional polymerizable monomer may be used. Is preferable. That is, in the present disclosure, from the viewpoint of improving the scratch resistance of the image, it is more preferable that the bifunctional polymerizable monomer is 60% by mass or more based on the total mass of the polymerizable compound.

The polymerizable compound is preferably an ethylenically unsaturated monomer having an ethylenically unsaturated group from the viewpoint of improving scratch resistance. The ethylenically unsaturated monomer having an ethylenically unsaturated group includes a monofunctional ethylenically unsaturated monomer and a polyfunctional ethylenically unsaturated monomer.

The monofunctional ethylenically unsaturated monomer is a compound having one ethylenically unsaturated group, for example, monofunctional (meth) acrylate, monofunctional (meth) acrylamide, monofunctional aromatic vinyl compound, monofunctional vinyl ether and Examples include monofunctional N-vinyl compounds.

The polyfunctional ethylenically unsaturated monomer is a compound having two or more ethylenically unsaturated groups, and examples thereof include polyfunctional (meth) acrylate and polyfunctional vinyl ether.

Examples of the monofunctional (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, hexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. , Butyl-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) Acrylate, 4-n-Butylcyclohexyl (meth) acrylate, 4-tert-butylcyclohexyl (meth) acrylate, Bornyl (meth) acrylate, Isobornyl (meth) acrylate, 2-ethylhexyldiglycol (meth) acrylate, Butoxyethyl ( Meta) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, cyanoethyl (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 2- (2-butoxyethoxy) ethyl (meth) acrylate, ethyl carbitol (meth) acrylate, 2,2,2-tetrafluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecyl (meth) acrylate, 4-butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate , 2-Phenoxymethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydro Flufuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) Acrylate, 3-hydroxybutyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, die Chilaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide (Meta) acrylate, polyethylene oxide monoalkyl ether (meth) acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-Methylloyloxyethyl-2-hydroxypropylphthalate, butoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3- Phenoxypropyl (meth) acrylate, ethylene oxide (EO) modified phenol (meth) acrylate, EO modified cresol (meth) acrylate, EO modified nonylphenol (meth) acrylate, propylene oxide (PO) modified nonylphenol (meth) acrylate, EO modified-2 -Ethylhexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (3-ethyl-3-oxetanylmethyl) (meth) acrylate and phenoxy Examples include ethylene glycol (meth) acrylate.

Examples of the monofunctional (meth) acrylamide include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, Nn-butyl (meth) acrylamide, and the like. Nt-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl Examples include (meth) acrylamide and (meth) acryloylmorpholin.

Examples of the monofunctional aromatic vinyl compound include styrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, vinyl benzoic acid methyl ester, and 3-methyl. Styrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene,3-octyl Styrene, 4-octyl styrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isopropenyl styrene, butenyl styrene, octenyl styrene, 4-t-butoxycarbonyl styrene and 4- Included is t-butoxystyrene.

Examples of the monofunctional vinyl ether include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexylmethyl vinyl ether and 4-methyl. Cyclohexylmethyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydro Flufuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexylmethylvinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chlorethyl vinyl ether, chlorbutyl vinyl ether, chloroethoxyethyl vinyl ether , Phenylethyl vinyl ether and phenoxypolyethylene glycol vinyl ether.

Examples of the monofunctional N-vinyl compound include N-vinyl-ε-caprolactam and N-vinylpyrrolidone.

Examples of the polyfunctional (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and dipropylene glycol di (meth). Acrylate, Tripropylene glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, Polypropylene glycol di (meth) acrylate, Butylene glycol di (meth) acrylate, Tetraethylene glycol di (meth) acrylate, Neopentyl glycol di (meth) ) Acrylate, 3-Methyl-1,5-pentanediol di (meth) acrylate, hexanediol di (meth) acrylate, heptanediol di (meth) acrylate, EO-modified neopentyl glycol di (meth) acrylate, PO-modified neopentyl Glycoldi (meth) acrylate, EO-modified hexanediol di (meth) acrylate, PO-modified hexanediol di (meth) acrylate, octanediol di (meth) acrylate, nonanediol di (meth) acrylate, decandiol di (meth) acrylate , Dodecanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl Etherdi (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, trimethylol ethanetri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane EO-added tri (meth) acrylate, pentaerythritol tri. (Meta) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylol propane , Glycerin polyglycidyl ether poly (meth) acrylate and tris (2-acryloyloxyethyl) isocyanurate.

Examples of the polyfunctional vinyl ether include 1,4-butanediol divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, and hexanediol di. Vinyl ether, 1,4-cyclohexanedimethanol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylol ethane trivinyl ether, trimethylol propanetrivinyl ether, ditrimethylol propanetetravinyl ether, glycerin trivinyl ether, pentaerythritol Tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, EO-added trimethylolpropane trivinyl ether, PO-added trimethylolpropanetrivinyl ether, EO-added ditrimethylolpropanetetravinyl ether, PO-added ditrimethylolpropanetetravinyl ether, EO-added penta Examples thereof include erythritol tetravinyl ether, PO-added pentaerythritol tetravinyl ether, EO-added dipentaerythritol hexavinyl ether and PO-added dipentaerythritol hexavinyl ether.

In the present disclosure, from the viewpoint of improving the scratch resistance of the image, it is preferable that at least one of the polymerizable compounds is a polymerizable compound containing an ethylene oxide chain. When a polymerizable compound containing an ethylene oxide chain is contained in the ink composition, the hydrophobicity of the ink composition is lowered. When the hydrophobicity of the ink composition is reduced, it becomes difficult for oxygen to dissolve in the ink composition. By making it difficult for oxygen to dissolve, the polymerization reaction is promoted, the curability is improved, and the scratch resistance of the image is improved. Since the code image has a large surface area as compared with the solid image, it is difficult to cure, but even if it is a code image, an image having excellent scratch resistance can be obtained.

In the polymerizable compound containing an ethylene oxide chain, the number of moles of the ethylene oxide chain added is not particularly limited, but is preferably 1 to 20 and more preferably 2 to 15 from the viewpoint of improving the scratch resistance of the image. 10 is more preferable.

Examples of the polymerizable compound containing an ethylene oxide chain include butoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, EO-modified phenol (meth) acrylate, EO-modified cresol (meth) acrylate, and EO-modified nonylphenol (meth) acrylate. Monofunctional (meth) acrylate containing ethylene oxide chains such as;
Monofunctional vinyl ether containing ethylene oxide chains such as methoxypolyethylene glycol vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, and phenoxy polyethylene glycol vinyl ether;
Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, EO-modified neopentyl glycol di (meth) Polyfunctional (meth) acrylate containing ethylene oxide chains such as acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate; and
Examples thereof include polyfunctional vinyl ethers containing ethylene oxide chains such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, and polyethylene glycol divinyl ether.

Among them, as the polymerizable compound containing an ethylene oxide chain, a polyfunctional (meth) acrylate containing an ethylene oxide chain is preferable, and ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetra. At least one selected from the group consisting of ethylene glycol di (meth) acrylate and polyethylene glycol di (meth) acrylate is more preferable.

The content of the polymerizable compound in the ink composition is preferably 70% by mass to 95% by mass, more preferably 80% by mass to 95% by mass, based on the total mass of the ink composition.

<Polymerization initiator>
The ink composition of the present disclosure contains a polymerization initiator. The polymerization initiator is preferably a radical polymerization initiator that generates radicals.

Examples of the radical polymerization initiator include (a) an alkylphenone compound, (b) an acylphosphine oxide compound, (c) an aromatic onium salt compound, (d) an organic peroxide, (e) a thio compound, and (f) a hexaary. Rubiimidazole compound, (g) ketooxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) compound having carbon halogen bond, and (m) ) Alkylamine compounds can be mentioned. The polymerization initiator may be used alone or in combination of two or more.

As the radical polymerization initiator, (a) an alkylphenone compound and (b) an acylphosphine oxide compound are preferable, and an acylphosphine oxide compound is more preferable. That is, in the present disclosure, the polymerization initiator is more preferably an acylphosphine oxide-based polymerization initiator.

Examples of the alkylphenone compound include an α-hydroxyketone compound and an α-aminoketone compound.

Examples of the α-hydroxyketone compound include 1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-2-hydroxy-1-propanone and 2-hydroxy-2-methyl-1-phenylpropan-1. -On and 1-hydroxycyclohexylphenyl ketones include.

Examples of the α-aminoketone compound include 2-methyl-1-phenyl-2-morpholinopropane-1-one, 2-methyl-1- [4- (hexyl) phenyl] -2-morpholinopropane-1-one, and the like. 2-Ethyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1-one, 2-dimethyl Amino-2- (4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) -butane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane -1-one), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone and 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1-[ 4- (4-morpholinyl) phenyl] -1-butanone can be mentioned.

Examples of the acylphosphine oxide compound include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,6-dimethylbenzoyl) phenylphosphine oxide, and bis (2,4,6-trimethylbenzoyl) -2-methoxy. Phenylphosphine oxide, bis (2,6-dimethylbenzoyl) -2-methoxyphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dimethoxyphenylphosphine oxide, bis (2,6-dimethylbenzoyl) ) -2,4-Dimethoxyphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dipentyloxyphenylphosphine oxide, bis (2,6-dimethylbenzoyl) -2,4-dipentyloxyphenyl Phosphine oxide, 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, 2,6-dimethylbenzoylethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl)- 2,4,4-trimethylpentylphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoylmethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl (4-pentyloxyphenyl) Examples include phenylphosphine oxide and 2,6-dimethylbenzoyl (4-pentyloxyphenyl) phenylphosphine oxide.

Among them, as the acylphosphine oxide compound, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are preferable, and bis (2,4,6-trimethylbenzoyl) phenyl. Phosphine oxide is more preferred. Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide has been introduced under the product name "Omnirad 819" by IGM Resins B.I. V. It is available from the company.

The content of the polymerization initiator in the ink composition is preferably 1.0% by mass to 15.0% by mass, more preferably 1.5% by mass to 10.0% by mass, based on the total mass of the ink composition. It is preferable, and more preferably 2.0% by mass to 6.0% by mass.

<Sensitizer>
The ink composition of the present disclosure may contain a sensitizer in order to absorb specific active energy rays and accelerate the decomposition of the polymerization initiator. The sensitizer may be used alone or in combination of two or more.

The sensitizer preferably has a molecular weight of 1000 or more, and more preferably 1500 or more, from the viewpoint of improving the scratch resistance of the image. From the viewpoint of appropriately adjusting the viscosity of the ink composition, the molecular weight of the sensitizer is preferably 100,000 or less, more preferably 10,000 or less. When the molecular weight of the sensitizer is 1000 or more, unreacted polymerizable monomer is unlikely to remain after the completion of the polymerization reaction. For example, when the base material is a food packaging material or a cosmetic packaging material, it is preferable because the transfer of the unreacted polymerizable monomer to the food or cosmetic is suppressed.

The molecular weight of the sensitizer is measured using a mass spectrometer, for example, the product name "API3200 system" of Siex.

Examples of the sensitizer include polynuclear aromatic compounds (for example, pyrene, perylene, triphenylene, and 2-ethyl-9,10-dimethoxyanthracene) and xanthene compounds (for example, fluoressein, eosin, erythrosin, and rhodamine B). , And Rose Bengal), cyanine compounds (eg, thiacarbocyanin, oxacarbocyanin), merocyanin compounds (eg, merocyanin, and carbomerocyanin), thiazine compounds (eg, thionin, methylene blue, and toluidine blue), acrydin Systems compounds (eg, acrydin orange, chloroflavin, and acryflabin), anthracene compounds (eg, anthracene), squalium compounds (eg, squalium), coumarin compounds (eg, 7-diethylamino-4-methylcoumarin), thioxanthone. Examples thereof include system compounds (for example, isopropylthioxanthone) and thiochromanon compounds (for example, thiochromanone). Among them, as the sensitizer, a thioxanthone compound is preferable from the viewpoint of improving the scratch resistance of the image.

As the thioxanthone-based compound, a compound represented by the following formula (4) is preferable.

In formula (4), R ⁵¹ to R ⁵⁸ are independently hydrogen atom, alkyl group, halogen atom, hydroxy group, cyano group, nitro group, amino group, alkylthio group and alkylamino group (mono- and di-substituted). ), Alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxy group or sulfo group.

In the alkyl group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, and acyl group, the number of carbon atoms in the alkyl moiety is preferably 1 to 20, more preferably 1 to 8. It is more preferably 1 to 4.

The acyloxy group may be an aryloxycarbonyl group. The acyl group may be an arylcarbonyl group. In the aryloxycarbonyl group and the arylcarbonyl group, the number of carbon atoms in the aryl portion is preferably 6 to 14, and more preferably 6 to 10.

The ^{two adjacent pieces in R 51} to R ⁵⁸ may be connected to each other to form a ring structure.
Examples of the ring structure include a 5-membered or 6-membered monocyclic structure; and a binuclear ring (for example, a condensed ring) in which two 5-membered or 6-membered monocyclic structures are combined.
The 5- or 6-membered monocyclic structure includes an aliphatic ring, an aromatic ring, and a heterocycle. Heteroatoms in the hetero ring include N, O, and S. The combination of monocyclic rings in the binuclear ring includes a combination of an aliphatic ring and an aliphatic ring, a combination of an aliphatic ring and an aromatic ring, a combination of an aliphatic ring and a heterocycle, and an aromatic ring and an aromatic ring. The combination with, the combination of the aromatic ring and the hetero ring, and the combination of the hetero ring and the hetero ring can be mentioned.

The ring structure may have a substituent. Substituents include alkyl groups, alkyl halide groups, halogen atoms, hydroxy groups, cyano groups, nitro groups, amino groups, alkylthio groups, alkylamino groups, alkoxy groups, alkoxycarbonyl groups, acyloxy groups, acyl groups and carboxy groups. And a sulfo group.

As the halogen atom, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom is preferable, a chlorine atom, a bromine atom or an iodine atom is more preferable, and a chlorine atom or a bromine atom is further preferable.

As the alkyl halide group, an alkyl fluoride group is preferable.

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-ethoxy Carbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfurylthioxanthone, 3,4-di [2- (2-methoxy) Ethoxy) 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-dicarboxyimide, n-octylthioxanthone-3,4-dicarboxyimide, N- (1,1) , 3,3-Tetramethylbutyl) thioxanthone-3,4-dicarboxyimide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol Esters and 2-hydroxy-3- (3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy) -N, N, N-trimethyl-1-propaneaminium chloride can be mentioned.

Among them, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, or 4-isopropylthioxanthone is preferable as the thioxanthone-based compound from the viewpoint of improving availability and scratch resistance of the image.

The thioxanthone-based compound may be a commercially available product on the market. Examples of commercially available products include the SPEEDCURE series manufactured by Lambson (for example, SPEEDCURE 7010, SPEEDCURE CPTX and SPEEDCURE ITX). Examples of the sensitizer include polynuclear aromatics (eg, pyrene, perylene, triphenylene, 2-ethyl-9,10-dimethoxyanthracene, etc.), xanthenes (eg, fluoressein, eosin, erythrosin, rhodamine B, etc.). Rose Bengal, etc.), cyanines (eg, thiacarbocyanine, oxacarbocyanine, etc.), merocyanines (eg, merocyanine, carbomerocyanin, etc.), thiadins (eg, thionin, methylene blue, toluidine blue, etc.), acridines (eg, erythinine, etc. , Acridine orange, chloroflavin, acryflabin, etc.), anthracenes (eg, anthracene, etc.), squaliums (eg, squalium, etc.), coumarins (eg, 7-diethylamino-4-methylcoumarin, etc.), thioxanthones (eg, 7-diethylamino-4-methylcoumarin, etc.) , Isopropylthioxanthone, etc.), thiochromanones (for example, thiochromanone, etc.) and the like.
Among them, as the sensitizer, thioxanthones are preferable, and isopropylthioxanthone is more preferable.
Further, the sensitizer may be used alone or in combination of two or more.

The content of the sensitizer in the ink composition is preferably 1.0% by mass to 15.0% by mass, more preferably 1.5% by mass to 10.0% by mass, based on the total mass of the ink composition. It is preferable, and more preferably 2.0% by mass to 6.0% by mass.

<Surfactant>
The ink composition of the present disclosure may contain a surfactant from the viewpoint of improving ejection stability. The surfactant may be used alone or in combination of two or more.

Examples of the surfactant include those described in JP-A-62-173436 and JP-A-62-183457. Examples of the surfactant include anionic surfactants such as dialkyl sulfosuccinate, alkylnaphthalene sulfonate, and fatty acid salt; polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, acetylene glycol, and polyoxyethylene poly. Nonionic surfactants such as oxypropylene block copolymers; and cationic surfactants such as alkylamine salts and quaternary ammonium salts can be mentioned. Further, the surfactant may be a fluorine-based surfactant or a silicone-based surfactant.

In the present disclosure, the surfactant is preferably a silicone-based surfactant from the viewpoint of improving the adhesion to the base material. Examples of the silicone-based surfactant include a polysiloxane compound, and a modified polysiloxane compound in which an organic group is introduced into a part of the methyl group of dimethylpolysiloxane is preferable. Modifications include polyether denaturation, methylstyrene denaturation, alcohol denaturation, alkyl denaturation, aralkyl denaturation, fatty acid ester denaturation, epoxy denaturation, amine denaturation, amino denaturation, and mercapto denaturation. A plurality of types of organic machines may be introduced into a part of the methyl group of dimethylpolysiloxane. Among them, a polyether-modified polysiloxane compound is preferable as the silicone-based surfactant from the viewpoint of discharge stability.

Examples of the polyether-modified polysiloxane compound include SILWET L-7604, SILWET L-7607N, SILWET FZ-2104 and SILWET FZ-2161 (manufactured by Momentive Performance Materials Japan); BYK306, BYK307, BYK331, BYK333, BYK347 and BYK348 (manufactured by BYK Chemie); and KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, Examples thereof include KF-643, KF-6020, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015 and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).

The content of the surfactant in the ink composition is preferably 0.001% by mass to 3.0% by mass, more preferably 0.01% by mass to 2.0% by mass, based on the total mass of the ink composition. It is preferable, and more preferably 0.05% by mass to 1.0% by mass.

<Other ingredients>
The ink composition of the present disclosure may contain a cosensitizer, an ultraviolet absorber, an antioxidant, an antioxidant, a conductive salt, a solvent, a basic compound and the like, if necessary, in addition to the above components. ..

<Physical characteristics of ink composition>
[PH]
The pH of the ink composition at 25 ° C. is preferably 7 to 10, more preferably 7.5 to 9.5, from the viewpoint of ejection stability.

The pH is measured using a pH meter, for example, a value measured using a pH meter (model number: HM-31, manufactured by Toa DKK Corporation).

〔viscosity〕
The viscosity of the ink composition at 25 ° C. is preferably 0.5 mPa · s to 30 mPa · s, more preferably 2 mPa · s to 20 mPa · s, further preferably 2 mPa · s to 15 mPa · s, and 3 mPa · s. It is particularly preferably about 10 mPa · s.

Viscosity is a value measured using a viscometer, for example, using VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD).

〔surface tension〕
The surface tension of the ink composition at 25 ° C. is preferably 60 mN / m or less, 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 tensiometer, and is a value measured by a plate method using, for example, an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

[Image recording method]
The image recording method of the present disclosure includes a step of recording an image on a substrate by an inkjet recording method using the above ink composition, and a step of irradiating an active energy ray.

-Image recording process-
In the image recording method of the present disclosure, first, an image is recorded on a substrate by an inkjet recording method using an ink composition.

〔Base material〕
The base material is not particularly limited as long as it can form an image, and examples thereof include paper, cloth, wood, a metal plate, and a plastic film.

Examples of the paper include so-called high-quality paper, coated paper, general printing paper such as art paper, and inkjet recording paper used for general offset printing.

Further, the base material may be a non-permeable base material. “Non-permeable” means that the amount of water absorbed in the ink composition is small or does not absorb water, and specifically, the amount of water absorbed is 10.0 g / m ² or less. To say.

Examples of the impermeable substrate include metals (for example, aluminum foil), plastic films (for example, polyvinyl chloride resin, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, and the like. Polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate and polyvinyl acetate), plastics and glass.

The non-permeable base material may be surface-treated. Examples of the surface treatment include corona treatment, plasma treatment, frame treatment, heat treatment, abrasion treatment, light irradiation treatment (UV treatment), and flame treatment.

The image recorded in this step is preferably a code image, and the code image is preferably a barcode, QR code or dot code. A barcode is, for example, an image in which a plurality of lines having different thicknesses are arranged in a striped pattern. The QR code is, for example, an image in which a plurality of squares of different sizes are formed in a vertical and horizontal mosaic pattern. The dot code is, for example, an image in which extremely small points are arranged in a range of about 2 mm square. The dot code is provided as a "screen code" by Apollo Japan.

Further, the image recorded in this step is preferably an image for alignment, that is, a register mark. For example, a desired image is recorded on the surface of the substrate and a register mark is recorded. When recording a desired image on the back surface of the substrate, the register mark is irradiated with visible light and the register mark is read. After aligning the front surface and the back surface, a desired image can be recorded on the back surface of the base material. Examples of the register mark include an L-shaped mark and a + -shaped mark.

[Inkjet recording method]
The inkjet recording method is not particularly limited, and is a known method, for example, a charge control method for ejecting an ink composition using an electrostatic attraction, a drop-on-demand method (pressure pulse method) using the vibration pressure of a piezo element. ), An acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink composition to eject the ink composition using radiation pressure, and heats the ink composition to form bubbles and uses the generated pressure. Thermal inkjet (bubble jet (registered trademark)) method can be mentioned.

As an inkjet recording method, in particular, by the method described in JP-A-54-59936, an ink composition subjected to the action of thermal energy causes a rapid volume change, and the ink composition is caused by the acting force due to this state change. An inkjet recording method in which an object is ejected from a nozzle can be effectively used.

Further, for the inkjet recording method, the method described in paragraphs 093 to 0105 of JP-A-2003-306623 can also be referred to.

As the inkjet head used in the inkjet recording method, a short serial head is used, and a shuttle method in which recording is performed while scanning the head in the width direction of the base material and a recording element are arranged corresponding to the entire area of one side of the base material. An example is a line method using a line head that has been used.

In the line method, a pattern can be formed on the entire surface of the base material by scanning the base material in a direction intersecting the arrangement direction of the recording elements, and a transport system such as a carriage that scans a short head becomes unnecessary. Further, since the movement of the carriage and the complicated scanning control with the base material are not required and only the base material moves, the recording speed can be increased as compared with the shuttle method.

In the image recording method of the present disclosure, either the shuttle method or the line method may be used.

The amount of droplets of the ink composition ejected from the inkjet head is preferably 1 pL (picolitre) to 20 pL, more preferably 3 pL to 15 pL.

-Active energy ray irradiation process-
In the image recording method of the present disclosure, it is preferable to irradiate the image recorded in the image recording step with active energy rays. The polymerizable compound in the image is polymerized and cured by irradiation with active energy rays. Examples of the active energy ray include ultraviolet rays, visible rays and electron beams, and among them, ultraviolet rays (hereinafter, also referred to as “UV”) and electron beams are preferable.

The peak wavelength of ultraviolet rays is preferably 200 nm to 405 nm, more preferably 220 nm to 400 nm, and even more preferably 240 nm to 390 nm.

^{UV, 20mJ / cm 2 ~ 5J /} cm 2, and preferably from being irradiated at an energy of ^{100mJ / cm 2 ~ 1,500mJ / cm} 2. The irradiation time is preferably 0.01 seconds to 120 seconds, more preferably 0.1 seconds to 90 seconds. As the irradiation conditions and the basic irradiation method, the irradiation conditions and the irradiation method disclosed in Japanese Patent Application Laid-Open No. 60-132767 can be applied. Specifically, as an irradiation method, light sources are provided on both sides of the head unit including the ink composition ejection device, and the head unit and the light source are scanned by a so-called shuttle method, or another light source that does not involve driving is used. The method used is preferred.

Mercury lamps, gas lasers and solid-state lasers are mainly used as light sources for irradiating ultraviolet rays, and mercury lamps, metal halide lamps and ultraviolet fluorescent lamps are widely known. In addition, replacement of the light source with a GaN (gallium nitride) -based semiconductor ultraviolet light emitting device is very useful industrially and environmentally, and UV-LED (light emitting diode) and UV-LD (laser diode) are small and expensive. It has a long life, high efficiency, and low cost, and is expected as a light source for ultraviolet irradiation. Among them, as the light source for irradiating ultraviolet rays, a metal halide lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp or a UV-LED is preferable.

-Other processes-
The image recording method of the present disclosure may include steps other than the image recording step and the active energy ray irradiation step. Other steps include, for example, a drying step in which an image is recorded and then dried before being irradiated with active energy rays.

The drying method is not particularly limited, and a known method can be used. Examples of the drying means include known heating means such as a heater, known blowing means such as a dryer, and means combining these.

Examples of the method of drying the image include a method of applying heat with a heater or the like from the side opposite to the image recording surface of the base material, a method of applying warm air or hot air to the image recording surface of the base material, and a method of applying warm air or hot air to the image recording surface of the base material. Alternatively, a method of applying heat with an infrared heater from the side opposite to the image recording surface, and a method of combining these can be mentioned.

The heating temperature for heating is preferably 60 ° C. or higher, more preferably 65 ° C. or higher, and particularly preferably 70 ° C. or higher. The upper limit of the heating temperature is not particularly limited, but is preferably 150 ° C. or lower, for example.

The heating time for heating is not particularly limited, but is preferably 1 second to 300 seconds, more preferably 1 second to 30 seconds.

Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to the following Examples as long as the gist of the disclosure is not exceeded.

Details of the photochromic compound, polymerizable compound, polymerization initiator, sensitizer and surfactant used in Examples and Comparative Examples are as follows. In Tables 1 and 2, "-" is shown for the components not contained.

<Photochromic compound>
・ P-1 (spiropyran compound) ・ ・ ・ Spiro [2H-1-benzopyran-2,2'-indoline]
・ P-2 (spiropyran compound) ・ ・ ・ Spiroindolinonaphthopyran ・ P-3 (spiroxazine compound) ・ ・ ・ 1,3-dihydro-1,3,3-trimethylspiro [2H-indole-2] , 3'-[3H] Naft [2,1-b]-[1,4] Oxazine]
・ P-4 (naphthopyran compound) ・ ・ ・ 3,3-diphenyl-3H-naphtho [2,1-b] pyran ・ P-5 (diarylethene compound) ・ ・ ・ Compound represented by the following structural formula

Tables 1 and 2 describe the types and types of photochromic compounds, and the content (mass%) of photochromic compounds in Examples and Comparative Examples.

<Polymerizable compound>
SR344: Polyethylene glycol (400) diacrylate, manufactured by Sartomer, molecular weight 508.
SR341: 3-Methyl-1,5-pentanediol diacrylate, manufactured by Sartomer, molecular weight 226
-A-200: Polyethylene glycol (200) diacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., molecular weight 308
SR238F: 1,6-hexanediol diacrylate, manufactured by Sartomer, molecular weight 254.3
SR506: Isobornyl acrylate, manufactured by Sartomer, molecular weight 208.3
4-HBA: 4-Hydroxybutyl acrylate, manufactured by Osaka Organic Chemical Co., Ltd., molecular weight 144
-A-600: Polyethylene glycol (600) diacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., molecular weight 708

Tables 1 and 2 describe the types of polymerizable compounds, the number of polymerizable groups (number of functional groups) and the molecular weight, and the content (mass%) of the polymerizable compounds in Examples and Comparative Examples.

<Polymerization initiator>
・ TPO
2,4,6-trimethylbenzoyldiphenylphosphine oxide, product name "Omnirad TPO H", IGM Resins B.I. V. Made by Omi. 819 ... Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, product name "Omnirad 819", IGM Resins B.I. V. Made by Omi. 2959
1- [4- (2-Hydroxyethoxy) phenyl] -2-methyl-2-hydroxy-1-propanol, product name "Omnirad 2959", IGM Resins B. et al. V. Made by Omi. 907
2-Methyl-1- [4- (Methylthio) Phenyl] -2-morpholinopropane-1-one, product name "Omnirad 907", IGM Resins B. et al. V. Made by the company

Tables 1 and 2 show the types and types of polymerization initiators, and the content (mass%) of the polymerization initiators in Examples and Comparative Examples.

<Sensitizer>
・ Speedcure7010
1,3-di ({α- [1-chloro-9-oxo-9H-thioxanthene-4-yl) oxy] acetylpoly [oxy (1-methylethylene)]} oxy) -2,2-bis ( {α- [1-Methylethylene)]} Oxymethyl) Propane, manufactured by Rambson, molecular weight 1839

Tables 1 and 2 show the content (mass%) of the sensitizer in Examples and Comparative Examples.

<Surfactant>
・ BYK307
Silicone-based surfactant, manufactured by BYK

Tables 1 and 2 show the content (mass%) of the surfactant in Examples and Comparative Examples.

[Example 1]
1 part by mass of the photochromic compound P-1, 75.9 parts by mass of SR341 as a polymerizable compound, 15 parts by mass of SR344, and Omi. 4 parts by mass of 819, 4 parts by mass of Speedcure 7010 as a thickener, and 0.1 parts by mass of BYK307 as a surfactant were mixed and stirred to obtain an ink composition. Stirring was performed at room temperature (25 ° C.) at 5,000 rpm for 20 minutes using a mixer (product name “L4R”, manufactured by Silberson).

[Examples 2 to 14 and Comparative Examples 1 to 2]
The photochromic compound, the polymerizable compound, the polymerization initiator, the sensitizer and the surfactant were mixed so as to have the contents shown in Tables 1 and 2, and an ink composition was prepared in the same manner as in Example 1. ..

(Image recording)
^{Japan Color evaluation on white paperboard (product name "Ibest W", 310 g / m 2} , manufactured by Nippon Paper Industries) using an inkjet recording device (product name "Jet Press (registered trademark) 720S", manufactured by Fujifilm). Image JC_TEST_FORM_3 was recorded. An offset printing machine was used to apply a topcoat varnish (product name "OP Top Varnish", manufactured by Tokyo Ink Co., Ltd.) on the white paperboard on which the image was recorded.

Next, using each ink composition prepared in Examples and Comparative Examples, a woman in the above evaluation image is drawn by an inkjet recording device (product name "DMP-2831", manufactured by FUJIFILM Dimatix). A code image was recorded in the part. Image recording was performed under the conditions of a resolution of 600 dpi (dot per inch) × 600 dpi and a droplet amount of 10 dpi. Bar codes, QR codes, and screen codes manufactured by Apollo Japan Co., Ltd. were recorded as code images. After image recording, an ultraviolet irradiation device (product name "CSOT-40", one 4KW metal halide lamp, manufactured by GS Nippon Battery Co., Ltd.) was used to irradiate the image with ultraviolet rays to obtain an image recording object 1. After recording the image, an image recorded object 2 was obtained by irradiating with ultraviolet rays using a UV-LED irradiation device (product name "GA5", LED light source having a wavelength of 385 nm, manufactured by Kyocera Corporation). Since the ink composition prepared in Comparative Example 1 had a high viscosity and could not be ejected using an inkjet recording device, the image recording material 1 and the image recording material 2 could not be obtained. Therefore, the evaluation described later is not performed. Further, the ink composition prepared in Comparative Example 2 had a high viscosity and could not be ejected at room temperature using an inkjet recording device. Therefore, the ink composition prepared in Comparative Example 2 was discharged using an inkjet recording device in a state of being heated to 80 ° C.

The image recording material 1 and the image recording material 2 obtained by using each ink composition were evaluated for initial invisibility, readability, invisibility over time, scratch resistance, and odor. The evaluation method is as follows. The evaluation results are shown in Tables 1 and 2.

<Initial invisibility>
Do you notice that the code image is recorded by presenting the image record 1 and the image record 2 to 10 people who do not know that the code image is recorded on the image record 1 and the image record 2? A test was conducted to determine whether or not. The smaller the number of people who notice, the better the invisibility. The evaluation criteria are as follows. A to C are practically acceptable levels.
A: No one notices it.
B: 1 to 4 people became popular.
C: 5-9 people became popular.
D: All 10 people noticed.

<Readability>
The image recording object 1 and the image recording object 2 were irradiated with black light. After the irradiation, 10 places where the code image was recorded were selected and a reading test was performed. The reading test was performed on each of the barcode, QR code and screen code. For barcodes, a readability test was conducted with a barcode reader. For the QR code, a readability test was conducted with a QR code reader using a smartphone (product name "iPhone (registered trademark) 5SE", manufactured by Apple Inc.). For the screen code, a reading test was conducted using a smartphone (product name "iPhone5SE", manufactured by Apple Inc.) with SC-link manufactured by Apollo Japan. The evaluation criteria are as follows. A to D are practically acceptable levels.
A: All 10 places were read.
B: 8 or 9 places were read.
C: 3 to 7 places were read.
D: One or two places were read.
E: I couldn't read it at all.

<Invisibility over time>
After irradiating the image recording object 1 and the image recording object 2 with black light, the images were allowed to stand for one day. To 10 people who did not know that the code image was recorded on the image recording material 1 and the image recording material 2, the image recording material 1 and the image recording material 2 one day after the irradiation with the black light were presented. A test was conducted to see if the code image was recorded. The smaller the number of people who notice, the better the invisibility. The evaluation criteria are as follows. A to C are practically acceptable levels.
A: No one notices it.
B: 1 to 4 people became popular.
C: 5-9 people became popular.
D: All 10 people noticed.

<Scratch resistance>
A 100-reciprocating friction test was performed on the parts of the image recording material 1 and the image recording material 2 on which the code image was recorded, with a load of 500 g. The Gakushin-type friction test was performed on the part where the barcode, QR code and screen code were recorded. After the friction test, it was irradiated with black light. After the irradiation, 10 places where the code image was recorded were selected and a reading test was performed. The reading test was performed on each of the barcode, QR code and screen code. For barcodes, a readability test was conducted with a barcode reader. For the QR code, a readability test was performed with a QR code reader using iPhone5SE. For the screen code, a reading test was performed using SC-link manufactured by Apollo Japan Co., Ltd. using iPhone5SE. The evaluation criteria are as follows. A to D are practically acceptable levels.
A: All 10 places were read.
B: 8 or 9 places were read.
C: 3 to 7 places were read.
D: One or two places were read.
E: I couldn't read it at all.

<Odor>
Ten subjects were allowed to smell the image recordings 1 and the image recordings 2, and a test was conducted to determine whether or not they felt odor. A and B are practically acceptable levels.
A: All 10 people did not feel the odor.
B: 1 to 4 people felt an odor.
C: More than 5 people felt an odor.

As shown in Tables 1 and 2, Examples 1 to 14 contain a photochromic compound, a polymerizable compound, and a polymerization initiator, and 70% by mass or more based on the total mass of the polymerizable compound has a molecular weight of 600. The following polymerizable compounds, which are excellent in invisibility, can be read by irradiation with ultraviolet rays, and can record an image having excellent invisibility after a lapse of a predetermined time after irradiation with ultraviolet rays.

Example 7 contained a polymerizable compound containing an ethylene oxide chain, and was found to be superior in scratch resistance and odor in the image recording 2 by irradiation with ultraviolet rays using an LED light source as compared with Example 8.

It was found that Example 8 contained a bifunctional polymerizable monomer and was superior in scratch resistance to the image recorded material 1 by irradiation with ultraviolet rays using a metal halide lamp as compared with Example 9.

It was found that Example 7 contained 60% by mass or more of the bifunctional polymerizable monomer with respect to the total mass of the polymerizable compound, and was excellent in scratch resistance of the screen cord in the image recording 2 as compared with Example 10. ..

Example 1 contained an acylphosphine-based polymerization initiator, and was found to be excellent in scratch resistance and odor in the image recording 2 as compared with Examples 11 and 12.

It was found that Example 1 contained a sensitizer and was superior in scratch resistance and odor in the image recording 2 as compared with Examples 13 and 14.

On the other hand, in Comparative Example 1, it was found that the viscosity was high and the image could not be recorded by the inkjet recording method.

In Comparative Example 2, it was found that the content of the polymerizable compound having a molecular weight of 600 or less was less than 70% by mass with respect to the total mass of the polymerizable compound, and the invisibility with time was inferior.

Further, the ink composition prepared in Example 1 was introduced into the 6-throttle portion of the inkjet recording device (product name "Jet Press 540WV", manufactured by FUJIFILM Corporation). As a base material, a tube base material of OPP (biaxially stretched polypropylene film) was used. Images were recorded on the surface using color ink and white ink, and register marks were recorded using the ink composition prepared in Example 1. When recording an image on the back surface, visible light was irradiated to read the register mark, and the front surface and the back surface were aligned. Then, an image was recorded on the back surface using color ink and white ink. The register mark has since disappeared. That is, the image for alignment recorded using the ink composition of the present disclosure allows a desired image to be recorded at a predetermined position on the substrate. Further, since the image for alignment becomes invisible after a lapse of a predetermined period, the aesthetic appearance of the desired image recorded on the base material is not spoiled.

The disclosure of Japanese Patent Application No. 2019-205294 filed on November 13, 2019 is incorporated herein by reference in its entirety. Also, all documents, patent applications and technical standards described herein are to the same extent as if the individual documents, patent applications and technical standards were specifically and individually stated to be incorporated by reference. , Incorporated by reference herein.

Claims (10)

1. Contains photochromic compounds, polymerizable compounds, and polymerization initiators
   An ink composition for inkjet recording in which 70% by mass or more is a polymerizable compound having a molecular weight of 600 or less with respect to the total mass of the polymerizable compound.
2. The ink composition for inkjet recording according to claim 1, wherein the photochromic compound is at least one selected from the group consisting of a spiropyran compound, a spirooxazine compound, a naphthopirane compound and a diarylethene compound.
3. The ink composition for inkjet recording according to claim 1 or 2, wherein 60% by mass or more is a polyfunctional polymerizable monomer with respect to the total mass of the polymerizable compound.
4. The ink composition for inkjet recording according to any one of claims 1 to 3, further comprising a sensitizer having a molecular weight of 1000 or more.
5. The ink composition for inkjet recording according to claim 4, wherein the sensitizer is a thioxanthone-based compound.
6. The ink composition for inkjet recording according to any one of claims 1 to 5, wherein at least one of the polymerizable compounds is a polymerizable compound containing an ethylene oxide chain.
7. The ink composition for inkjet recording according to any one of claims 1 to 6, wherein the polymerization initiator is an acylphosphine oxide-based polymerization initiator.
8. A step of recording a code image on a substrate by an inkjet recording method using the ink composition for inkjet recording according to any one of claims 1 to 7.
   An image recording method including a step of irradiating an active energy ray.
9. The image recording method according to claim 8, wherein the code image is a barcode, QR code (registered trademark) or dot code.
10. A step of recording an image for alignment on a substrate by an inkjet recording method using the ink composition for inkjet recording according to any one of claims 1 to 7.
    An image recording method including a step of irradiating an active energy ray.