JP2011094092A - Liquid composition, inkjet recording method, and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curable liquid composition which has an enough water solubility, is promptly cured by an active energy ray, has an excellent film strength since it forms a cured product with a high degree of crosslinking, and does not ruin the stability due to a hydrolysis etc. even when used for an aqueous liquid composition and ink. <P>SOLUTION: The liquid composition contains at least a curable material, and is cured by the irradiation of the active energy ray, wherein the curable material contains a multifunctional amide compound of a specified structure and a multifunctional azide compound of a specified structure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid composition, an ink jet recording method, and an ink jet recording apparatus.

  Conventionally, a method for forming an image by applying a liquid composition to a recording medium and irradiating the recording medium with an active energy ray to cure a curable substance in the liquid composition to form a cured film is known. It is widely applied. Among them, there is a technique in which a liquid composition containing an active energy ray curable substance (hereinafter referred to as a curable substance) is applied to an ink jet recording method as an ink. In particular, a technique using an active energy ray-curable liquid composition to which an aqueous curable material is applied is extremely useful with an extremely low environmental load.

  Therefore, the development of aqueous liquid compositions and the development of water-soluble curable substances that can be applied to them are required, but the curable substances used in aqueous liquid compositions include aqueous solution characteristics and cured films. Compatibility with characteristics is required. Especially when applied to ink jet recording, as an aqueous solution property, the substance before curing exhibits good water solubility, and even when coexisting with various colorants, the performance of the liquid composition does not deteriorate, and it can be stored at room temperature. It is required to be thermally stable and exhibit an appropriate low viscosity. Further, as cured film characteristics, high sensitivity to a specific light source, high curability in various recording media, high resistance to organic solvents and water, and stability without being discolored in various environments are required. .

  Heretofore, various curable substances have been proposed to satisfy the above-mentioned characteristics. For example, Patent Document 1 proposes a resin in which a plurality of aqueous polyfunctional acrylic compounds are mixed as a curable substance, and Patent Document 2 proposes a polymer compound that can be cross-linked between side chains. ing.

  However, the compounds described in Patent Documents 1 and 2 have the following problems according to the study by the present inventors. That is, since these curable substances have an ester group in the molecular structure, a dye that dissolves in an aqueous medium by an anionic group or a pigment dispersion in which a pigment is dispersed in an aqueous medium by an anionic group When used in combination with the body, the following phenomenon occurs. As the carboxylic acid is generated by hydrolysis of the ester group in the curable material, the pH of the liquid composition drops to the acidic range, causing dye precipitation and aggregation / sedimentation of the pigment dispersion. May cause problems. Furthermore, the curable substance in the ink (liquid composition) may generate an insoluble matter due to an unexpected reaction, which may cause a problem in ejection stability.

  On the other hand, the applicant of the present invention can suppress the generation amount of acid generated by hydrolysis by using a curable substance having an amide group or an imide structure adjacent to the crosslinkable group. It was clarified (see Patent Documents 3 and 4). According to this technique, high storage stability can be imparted to the liquid composition regardless of the color material type to be used.

  However, in recent years, image forming products using liquid compositions have dramatically increased the variety according to individual needs and the need for high image quality. Accordingly, it has become increasingly important for the above-described aqueous active energy ray-curable liquid composition to exhibit high curing performance even for various recording media. Technology that imparts high curing performance is essential.

  As a method for improving the curability of a photocurable composition, for example, a technique called a cationic curing resist that progresses in a chemically amplified type, or a technique called hybrid UV curing in which a composition has two functions of cationic curing and radical curing Has been reported. However, these compositions have few aqueous compounds, and when used in combination with a coloring material having an anionic group, the cationic catalyst that causes the curing reaction is deactivated, and the expected curing performance is exhibited. Often not.

  As another method, a technique called dual UV curing that improves the curing performance of a cured product by adding a thermosetting component to the photocurable composition has also been reported. However, when these compositions are used as liquid compositions in the form of ink, although the curing performance is improved, the thermal stability at room temperature is low and the viscosity of the liquid composition increases with time. It often happens.

  Furthermore, as another report example, there is one in which a compound containing an azide group that is aqueous and photocrosslinkable is used in the curable resin composition. The azide compound has long been used for a photoresist material. For example, a compound having two aromatic azide groups in a molecule (aromatic bisazide compound) can be used to photocur the cyclized rubber. Has been done.

  Among the reported examples of such an azide compound, Patent Document 5 is given as an example applied to an aqueous curable liquid composition. This is an aqueous azide compound by introducing an aqueous group into the molecule of the aromatic azide compound, and in combination with various aqueous polymer polymers, it is used as an aqueous photoresist, particularly as a black matrix forming material. It is what.

  Patent Document 2 cited above also describes an example in which a polymer having an azide group introduced in the side chain is used in the aqueous photocurable ink composition. However, since the curable resin composition containing an azide compound shown in Patent Document 2 or Patent Document 5 uses a polymer compound in the composition, particularly when used as a liquid composition applied to an inkjet system, If the viscosity is too high, the discharge performance may be insufficient. Further, in Patent Document 5, since the crosslinking reaction for imparting the curing performance is mainly only the dimerization reaction of the azide group itself, even if the cured resin is a polymer, the recording medium type and the color material type are used. Depending on the case, poor curing may occur. Furthermore, with respect to the curable resin composition containing these azide compounds, there is no example in which countermeasures have been taken against the problem of hydrolysis caused when used in combination with a coloring material containing an anionic group.

  As described above, in the prior art, particularly a photocurable aqueous liquid composition for inkjet is imparted with higher curing performance while maintaining sufficient aqueous solution characteristics, hydrolysis resistance, and high storage stability. This was difficult and new technological development was required.

International Publication No. 2007/036692 Pamphlet JP 2007-45872 A JP 2007-119449 A JP 2007-99802 A JP-A-11-160865

  The present invention has been made in view of the above problems. The purpose of the ink is to exhibit high storage stability regardless of the color material type used in combination and to exhibit high curing performance regardless of the color material type and the recording medium used, even when used as an ink containing a color material. An object of the present invention is to provide an active energy ray-curable liquid composition capable of forming a film. Another object of the present invention is to provide an ink jet recording method and an ink jet recording apparatus using the liquid composition capable of forming various high-quality images.

（一般式（１）中、Ｒ₁はｎ価の有機基を表す。Ｒ₂は水素原子又は１価の有機基を表す。Ｒ₃、Ｒ₄、及びＲ₅はそれぞれ独立に、水素原子、１価の有機基、又は構造中の炭素−炭素二重結合のα位若しくはβ位に１つのカルボニル基を含む１価の有機基を表す。ただし、Ｒ₃、Ｒ₄、及びＲ₅のうち少なくとも１つは構造中の炭素−炭素二重結合のα位若しくはβ位に１つのカルボニル基を含む１価の有機基である。ｎは２以上の整数を表す。）

（一般式（２）中、Ｒ₁はｎ価の有機基を表す。Ｒ₆及びＲ₇はそれぞれ独立に、水素原子又は１価の有機基を表す。ｎは２以上の整数を表す。）

（一般式（３）中、Ｒ₁₂は水素原子又は１価の有機基を表す。Ｒ₁₃はｍ価の有機基を表す。ｍは２以上の整数を表す。） The above object is achieved by the present invention described below. That is, the present invention is a liquid composition that contains at least a curable substance and is cured by irradiation with active energy rays, and the curable substance is represented by the following general formula (1). Including at least one selected from the group consisting of a polyfunctional amide compound and a polyfunctional amide compound represented by the following general formula (2), and a polyfunctional azide compound represented by the following general formula (3): It is the liquid composition characterized.

(In general formula (1), R ₁ represents an n-valent organic group. R ₂ represents a hydrogen atom or a monovalent organic group. R ₃ , R ₄ , and R ₅ are each independently a hydrogen atom, A monovalent organic group or a monovalent organic group containing one carbonyl group at the α-position or β-position of the carbon-carbon double bond in the structure, provided that R ₃ , R ₄ , and R ₅ (At least one is a monovalent organic group containing one carbonyl group at the α-position or β-position of the carbon-carbon double bond in the structure. N represents an integer of 2 or more.)

(In General Formula (2), R ₁ represents an n-valent organic group. R ₆ and R ₇ each independently represents a hydrogen atom or a monovalent organic group. N represents an integer of 2 or more.)

(In General Formula (3), R ₁₂ represents a hydrogen atom or a monovalent organic group. R ₁₃ represents an m-valent organic group. M represents an integer of 2 or more.)

  ADVANTAGE OF THE INVENTION According to this invention, the active energy ray hardening-type liquid composition excellent in the above-mentioned aqueous solution characteristic and hardening performance can be provided. In particular, it is possible to provide a water-based active energy ray-curable liquid composition that has a particularly excellent curing performance. In addition, according to the present invention, it is possible to provide an ink jet recording method and an ink jet recording apparatus capable of forming various high-quality images by using the liquid composition.

Hereinafter, the liquid composition of the present invention will be described in detail.
[Curable material]
As long as the curable substance used in the present invention contains a polyfunctional amide compound represented by the following general formula (1) or (2) and a polyfunctional azide compound represented by the following general formula (3). Good. In the present invention, by using the polyfunctional amide compound and the polyfunctional azide compound in combination, specifically excellent curing performance can be expressed.

（一般式（１）及び（２）中、Ｒ₁はｎ価の有機基を表す。Ｒ₂、Ｒ₆、及びＲ₇はそれぞれ独立に、水素原子又は１価の有機基を表す。ｎは２以上の整数を表す。一般式（１）中、Ｒ₃、Ｒ₄、及びＲ₅はそれぞれ独立に、水素原子、１価の有機基、又は構造中の炭素−炭素二重結合のα位若しくはβ位に１つのカルボニル基を含む１価の有機基を表す。ただし、Ｒ₃、Ｒ₄、及びＲ₅のうち少なくとも１つは構造中の炭素−炭素二重結合のα位若しくはβ位に１つのカルボニル基を含む１価の有機基である。）

(In the general formulas (1) and (2), R ₁ represents an n-valent organic group. R ₂ , R ₆ and R ₇ each independently represents a hydrogen atom or a monovalent organic group. Represents an integer greater than or equal to 2. In General formula (1), R < ₃ >, R < ₄ > and R < ₅ > are respectively independently a hydrogen atom, a monovalent organic group, or the alpha position of the carbon-carbon double bond in a structure. Or a monovalent organic group containing one carbonyl group at the β-position, provided that at least one of R ₃ , R ₄ and R ₅ is the α-position or β-position of the carbon-carbon double bond in the structure. Is a monovalent organic group containing one carbonyl group.)

（一般式（３）中、Ｒ₁₂は水素原子又は１価の有機基を表す。Ｒ₁₃はｍ価の有機基を表す。ｍは２以上の整数を表す。）

(In General Formula (3), R ₁₂ represents a hydrogen atom or a monovalent organic group. R ₁₃ represents an m-valent organic group. M represents an integer of 2 or more.)

The individual compounds are described below.
[Polyfunctional amide compound]
As described above, the polyfunctional amide compound used in the present invention has at least two carbonyl groups adjacent to the carbon-carbon double bond, and at least one of the carbonyl groups is an amide bond. Is a feature. It is also important that the compound is a polyfunctional compound containing at least two such double bonds. That is, any structure having the structure represented by the general formula (1) or (2) may be used.

As R ₁ in the above general formulas (1) and (2), various organic groups can be used as long as they are n-valent, but they are used in an aqueous photocurable liquid composition as in the present invention. When it does, it is preferable to have at least one hydrophilic group. Specific examples of the hydrophilic group include a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonic acid group, a phosphate group, an ether group, and an amide group. Further, when used in combination with the colorant having an anionic group, in order to suppress the hydrolysis of the polyfunctional amide compound, the structure of R ₁ is preferably an organic group other than an ester group.

If the molecular weight of R ₁ is too large, the density of the crosslinkable group with respect to the molecular weight of the polyfunctional amide compound may decrease, and the curability of the cured product may be insufficient. Therefore, the molecular weight of R ₁ is preferably 100,000 or less, more preferably 50,000 or less, most preferably 30,000 or less, and preferably 20 or more.

R ₃ , R ₄ , and R _{5 in the} general formula (1) are each a hydrogen atom, a monovalent organic group, or one carbonyl at the α-position or β-position of the carbon-carbon double bond in the structure. A monovalent organic group containing a group. R ₃ , R ₄ , and R ₅ are each a monovalent organic group that includes one carbonyl group at the α-position or β-position of the carbon-carbon double bond in the structure, It may be a salt structure such as an organic acid salt. When used in combination with a coloring material having an anionic group, the structure of R ₃ , R ₄ , and R ₅ is an organic group other than an ester group in order to suppress hydrolysis of the polyfunctional amide compound. Is preferred. Among them, the organic group adjacent to the carbon-carbon double bond is preferably an amide group, a carboxylic acid group, or a carboxylate group.

  Specific examples of the peripheral structure of the crosslinkable group in the polyfunctional amide compound include the following. Maleamic acid, maleamic acid salt, maleic acid diamide, maleimide, fumaric acid, fumarate, fumaric acid diamide, itaconic acid, itaconic acid salt, itaconic acid diamide, and itaconimide are preferred.

The structures of R ₂ , R ₆ , and R _{7 in} the general formulas (1) and (2) may be independently a hydrogen atom or a monovalent organic group. When used in combination with a coloring material having an anionic group, the structure of R ₂ , R ₆ , and R ₇ is an organic group other than an ester group in order to suppress hydrolysis of the polyfunctional amide compound. Is preferred.

  N in the general formulas (1) and (2) may be an integer of 2 or more. From the viewpoint of curing performance, n is preferably as large as possible. However, for example, when it is 10 or more, the molecular weight of the polyfunctional amide compound as a whole becomes too large, and the viscosity of the liquid composition may become too high.

  The molecular weight of the polyfunctional amide compound is preferably a relatively low molecular weight from the viewpoint of viscosity due to ejection performance when used for inkjet applications. Specifically, the molecular weight is preferably 5,000 or less, more preferably 3,500 or less, further preferably 2,000 or less, and preferably 100 or more.

The content of the polyfunctional amide compound in the liquid composition is preferably in the range of 0.1% by mass or more and 50.0% by mass or less based on the total mass of the liquid composition.
Examples of the method for synthesizing the polyfunctional amide compound used in the present invention include the following methods. First, the amide compound represented by the general formula (1) is obtained by subjecting maleic anhydride or itaconic anhydride to an addition-ring-opening reaction with a polyfunctional amine to obtain a polyfunctional maleamic acid compound or a polyfunctional maleamide compound. A functional itaconamide acid compound is obtained. A polyfunctional amic acid compound having a fuma skeleton can be obtained by subjecting the obtained polyfunctional amic acid compound to a cis-trans transition reaction. Further, by adding a base to this compound, a polyfunctional amide compound in which a part or all of the acid groups are in a salt form can be obtained (see the following formula (II)). Moreover, the amide compound represented by General formula (2) is obtained by performing dehydration ring-closing reaction with respect to the above-mentioned polyfunctional amic acid compound.

Examples of the structure of R _{1 in} the general formulas (1) and (2) are shown below with the structure of the precursor polyfunctional amine. Examples of the structure of the polyfunctional amine include an aliphatic skeleton and an aromatic skeleton. Specific examples include cyclohexanediamine, diaminoethane, piperazine, N, N′-dimethylethylenediamine, N, N′-diethylethylenediamine, diethylenetriamine, N, N′-bis (2-aminoethyl) -1,3-propanediamine. Aliphatic amines such as tris (2-aminoethyl) amine, diaminobenzene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylmethane, Aromatic amines such as N, N′-diphenylethylenediamine and 3,4,4′-triaminodiphenyl ether can be mentioned. Moreover, the polymer which has an amino group in a side chain can also be used, for example, polyamines, such as polyvinylamine, polyallylamine, and polyaminostyrene.

[Polyfunctional azide compound]
The polyfunctional azide compound used in the present invention is characterized by having an azide group directly bonded to two or more aromatic rings, and may be a structure represented by the above general formula (3).

R ₁₃ in the general formula (3) may be m-valent, and various organic groups can be used. When using together with the coloring material which has an anionic group, in order to suppress the hydrolysis of the said polyfunctional azide compound, it is preferable that they are organic groups other than an ester group. If the molecular weight of R ₁₃ is too large, the density of the azide group with respect to the molecular weight of the polyfunctional azide compound may decrease, and the cured product may have insufficient curing performance. Therefore, the molecular weight of R ₁₃ is preferably 3,000 or less, more preferably 2,000 or less, most preferably 1,000 or less, and preferably 20 or more.

R ₁₂ in the general formula (3) may be a hydrogen atom or a monovalent organic group, but when used in an aqueous photocurable liquid composition as in the present invention, at least one It preferably has a hydrophilic group. Specific examples of the hydrophilic group include an acidic group such as a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group, a salt type group thereof, a hydroxyl group, an ether group, and an amide group. When using in combination with a colorant that is dispersed or dissolved in an aqueous medium by the action of an anionic group, a compound having no ester group should be used in order to suppress hydrolysis of the polyfunctional azide compound. Is preferred.

  M in the general formula (3) may be an integer of 2 or more. From the viewpoint of curing performance, it is preferable that the m number is large. However, when the number is 10 or more, for example, the molecular weight of the polyfunctional azide compound as a whole becomes too large, and the viscosity of the liquid composition may become too high.

  The polyfunctional azide compound used in the present invention is preferably a structure represented by the following general formula (4) having a relatively wide conjugated structure in consideration of sensitivity to the light source used.

（一般式（４）中、Ｒ₁₄はそれぞれ独立に、水素原子、１価の有機基、又は構造中の各Ｒ₁₄が環をなすアルキレン鎖を表す。Ｘはそれぞれ独立に、Ｎａ、Ｋ、Ｌｉから選ばれる１価の金属原子を表す。）

(In General Formula (4), each R ₁₄ independently represents a hydrogen atom, a monovalent organic group, or an alkylene chain in which each R ₁₄ in the structure forms a ring. X independently represents Na, K, Represents a monovalent metal atom selected from Li)

  When the molecular weight of the polyfunctional azide compound is used as a liquid composition applied to an ink jet system, it is preferable that the molecular weight is relatively low from the viewpoint of viscosity due to ejection performance. Specifically, the molecular weight is preferably 5,000 or less, more preferably 3,500 or less, still more preferably 2,000 or less, and preferably 300 or more.

  The content of the polyfunctional azide compound in the liquid composition is preferably in the range of 0.1% by mass or more and 50.0% by mass or less based on the total mass of the liquid composition.

  In the present invention, the content of the polyfunctional azide compound relative to the polyfunctional amide compound is such that when the amount of the polyfunctional azide compound added is too large, the brown color of the polyfunctional azide compound stands out and the desired color is obtained. It may not develop. On the other hand, if the amount is too small, the curability of the cured product may be insufficient. Therefore, the content of the polyfunctional azide compound in the liquid composition is in the range of 0.1 parts by mass or more and 100.0 parts by mass or less when the addition amount of the polyfunctional amide compound is 100.0 parts by mass. Preferably there is. Furthermore, it is more preferable that the range is 1.0 part by mass or more and 80.0 parts by mass or less.

  The polyfunctional azide compound is preferably a compound having a stilbene skeleton, a dibenzylideneacetone skeleton, or a cinnamoyl skeleton. In the present invention, from the viewpoint of solubility as an aqueous liquid composition, it preferably has a sulfonic acid group, and particularly preferred are the compounds shown below. In the following structural formulas, X is independently Na, K, or Li.

[Polymerization initiator]
The liquid composition of the present invention may further contain a polymerization initiator. The polymerization initiator is not particularly limited as long as it generates an active species that causes the curable substance to start polymerization by the exchange of light. Since the curing reaction of the curable substance significantly proceeds due to the action of radicals, it is preferable to use a photoradical generator that generates radicals by transferring light as a polymerization initiator. The content (% by mass) of the polymerization initiator in the liquid composition is preferably 0.01% by mass or more and 20.0% by mass or less, and preferably 0.01% by mass or more and 10.0% by mass or less based on the total mass of the liquid composition. The mass% is more preferable, and 0.01 mass% or more and 5.0 mass% or less is most preferable. When there is too much content of a polymerization initiator, an unreacted polymerization initiator may remain in a cured film and the intensity | strength of a cured film may fall.

  The structure of the polymerization initiator is preferably a compound having a hydrophilic group in order to maximize the curing performance when used in an aqueous liquid composition as in the present invention. Specific examples of the hydrophilic group include an acidic group such as a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group, a salt type group thereof, a hydroxyl group, an ether group, and an amide group.

  Further, the hydrophilic group does not have an ester group in order to suppress hydrolysis of the polymerization initiator when used in combination with a colorant that is dispersed or dissolved in an aqueous medium by the action of an anionic group. It is preferable to use a compound. Specific structures of the polymerization initiator are shown below, but the polymerization initiator that can be used in the present invention is not limited to these structures.

  In the present invention, a polymerization initiator and a sensitizer can be used in combination, or two or more kinds of polymerization initiators can be used in combination. By using two or more kinds of polymerization initiators in combination, generation of further radicals can be expected using light having a wavelength that cannot be effectively used with one kind of polymerization initiator. Further, the polymerization initiator as described above is not necessarily used when an electron beam curing method in which a liquid composition is cured using an electron beam as an active energy beam.

[solvent]
The liquid composition of the present invention may be used as an aqueous liquid composition containing at least water as a solvent. In this case, the content of the curable substance is different depending on the application and style, and cannot be generally stated. However, in many cases, 1.0% by mass or more is preferable based on the total mass of the liquid composition. Further, the curable substance may not be dissolved in a solvent, but may be emulsified and dispersed using a known dispersion technique as appropriate, and used as an emulsion. Similarly, various encapsulation techniques can be applied.

  In addition to water, various organic solvents can also be included as components constituting the solvent in order to improve various performances and to the extent that the original characteristics are not impaired. For example, certain organic solvents are added for the purpose of imparting non-volatility to the liquid composition, adjusting the viscosity, adjusting the surface tension, imparting wettability to the recording medium, and the like. The organic solvents that can be used in the present invention are listed below. In the liquid composition of this invention, what was selected arbitrarily from these can be added 1 type or in combination of 2 or more types. For example, alkylene glycols such as ethylene glycol. Glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, and propylene glycol monomethyl ether. Monohydric alcohols such as methanol, ethanol, propanol, butanol and pentanol.

  The content of the solvent (water, organic solvent) is preferably 10.0% by mass or more and 90.0% by mass or less based on the total mass of the liquid composition.

[Other additives, etc.]
Further, the liquid composition of the present invention may contain a reactive diluent that is generally widely known. Representative examples include acryloylmorpholine, N-vinylpyrrolidone, acrylamide, methylenebisacrylamide, monosaccharide monoacrylate, oligoethylene oxide monoacrylate, and dibasic monoacrylate. However, when these diluents are also used in combination with a coloring material having an anionic group, in order to suppress hydrolysis of the diluent, it may be composed of organic groups other than ester groups in the structure. preferable. Moreover, the liquid composition of the present invention is intended to improve various performances, and can also contain various additives to the extent that the original properties are not impaired.

  The liquid composition of the present invention can be used as it is without containing a coloring material as described later. In this case, since a coloring material is not contained, a substantially colorless and transparent film can be obtained. Examples of the use of the liquid composition in a form not containing a coloring material include the following. For example, it is used for applications such as an undercoat for imparting various aptitudes to image recording to a recording medium, or an overcoat for the purpose of protecting the surface of an image formed with ordinary ink, and further providing decoration and gloss. be able to. In this case, the liquid composition can also contain a dispersion of colorless pigments or fine particles that are not intended for coloring, depending on applications such as oxidation prevention and fading prevention. By adding these, it is possible to improve various properties such as image quality, fastness and workability (handling property) of the recorded matter in both the undercoat and the overcoat.

  Further, the liquid composition of the present invention may contain a color material. In that case, the liquid composition according to the present invention can be used as an ink for forming an image. The configuration and the color material used in that case will be described.

[Color material]
The liquid composition of the present invention can be used as a colored active energy ray-curable ink that is cured by irradiation with active energy rays or the like when applied to an ink containing a coloring material. As the coloring material used in this case, it is preferable to use a pigment dispersion in which a pigment is dispersed in an aqueous medium. As the pigment dispersion, water-based gravure inks, water-based pigment dispersions for writing instruments, pigment dispersions used in conventionally known ink-jet inks, and the like can all be suitably used. In particular, a pigment dispersion in which a pigment is dispersed in an aqueous medium by the action of an anionic group is extremely suitable.

  In addition, when using the various pigments described above, a dispersant may be used in combination. As the dispersant, for example, a block polymer, a random polymer, a graft polymer, or the like can be used as long as it can stably disperse the pigment in the aqueous medium.

  In the case of using the above-described various pigments, so-called self-dispersing pigments that can be dispersed without using a dispersant by bonding ionic groups to the surface of the pigment particles can also be used. In addition, it is preferable that content (mass%) of the pigment in a liquid composition shall be 0.3 to 30.0 mass% on the basis of the total mass of a liquid composition.

  In the liquid composition of the present invention, various conventionally known dyes can also be used as the color material. The content (% by mass) of the dye in the liquid composition is preferably 0.1% by mass or more and 30.0% by mass or less based on the total mass of the liquid composition.

[Inkjet recording method and inkjet recording apparatus]
The inkjet recording method of the present invention comprises a step of applying the liquid composition of the present invention described above to a recording medium by ejecting it from an inkjet recording head, and an active energy ray on the recording medium to which the liquid composition has been applied. Irradiating to cure the liquid composition. The ink jet recording apparatus of the present invention includes an ink jet recording head for applying the liquid composition of the present invention described above to a recording medium, and an active energy ray for the liquid composition applied to the recording medium. Is provided. As described above, since the liquid composition of the present invention contains a curable substance suitable for an ink jet recording system, it provides excellent effects when applied to an ink jet recording method and a recording apparatus. Among them, as a liquid composition for discharging from a recording head using thermal energy, an extremely excellent effect is brought about. In addition, the liquid composition of the present invention is very effective as a liquid contained in a cartridge (liquid cartridge) having a liquid container, and as a filling liquid for the liquid cartridge.

[Characteristics of liquid composition]
As described above in detail with reference to preferred embodiments, according to the present invention, various characteristics are excellent, that is, composite characteristics such as aqueous solution characteristics, curing performance, liquid characteristics, cured film characteristics, and stability are combined. Thus, an active energy ray-curable liquid composition that is highly satisfying can be provided. In particular, the curing performance of the cured product exhibits characteristics that are specifically superior to those of conventional liquid compositions.

  As described above, the present inventors presume that the specific curing performance is manifested as follows. First, in the liquid composition of this invention, it is thought that it is because the photocrosslinking of an azide compound higher than before expresses.

Specifically, it is as follows. First, usually, an azide compound is excited by light to generate nitrogen and nitrene (the following formula (6)).

  In addition, in the photocrosslinking of an azide compound, a coupling reaction between the nitrenes or a radical addition reaction or a C—H insertion reaction is caused to a polymer in which the nitrene coexists to form a crosslinked structure. (Formula (7)).

  On the other hand, since nitrene is very high in activity, it is known that a reaction for drawing out hydrogen in other molecules and generating a primary amine occurs in competition with the crosslinking reaction (the following formula (8) )). And when an azide compound is used for the conventional photocurable liquid composition, these primary amine and its production | generation reaction hardly contribute to hardening reaction. Therefore, in the conventional photocurable liquid composition, the azide compound is excited by light irradiation, and among the generated nitrene, there are as many uncrosslinked components in the cured film as the number of molecules generated in the primary amine formation reaction. Since it remains, it is thought that there was a limit in improving the curability of the cured film.

  However, unlike the conventional liquid composition of the present invention, the polyfunctional amide compound is used as a compound used in combination with the azide compound. As a result, the following phenomenon is estimated to occur. That is, when the polyfunctional amide compound is used in combination, the above-described crosslinking reaction (formula (7)) not only proceeds, but also a primary amine (formula (8)) by-produced by the hydrogen abstraction reaction of nitrene. It is presumed that the nucleophilic addition reaction proceeds and crosslinking occurs (the following formula (9)). That is, since the carbon-carbon double bond in the polyfunctional amide compound used in the present invention has two or more electron-withdrawing carbonyl groups in the close position, the double bond is in an electron-deficient state. For this reason, not only the direct radical addition reaction with nitrene proceeds, but also the addition reaction proceeds with the primary amine produced as a by-product, so the uncrosslinked component is significantly reduced compared to the conventional liquid composition and compared with the conventional liquid composition. Thus, it is considered that specifically high curing performance is exhibited.

  In addition, the curing performance of the liquid composition of the present invention is not limited to the photocrosslinking of the polyfunctional azide compound as described above, but also includes radicals generated from a photoradical initiator as active species. It is also expressed by radical polymerization of a heavy bond. It is generally known that such radical polymerization is susceptible to polymerization inhibition by atmospheric oxygen. However, also from the viewpoint of oxygen inhibition, in the present invention, since the polyfunctional azide compound generates a nitrogen atom in a photoreaction by using the polyfunctional azide compound in combination (the above formula (6)), radical polymerization is performed. Oxygen concentration in the reaction field where the gas proceeds is reduced. That is, it is considered that polymerization proceeds more efficiently and high curing performance is expressed.

  Further, the effect of improving the curing performance in the liquid composition of the present invention is not only due to the two photocrosslinking / radical polymerization described above, but also due to the photodimerization of the double bond portion itself of the polyfunctional amide compound as compared with the conventional one. It is thought that it is easy to express. That is, since the carbon-carbon double bond in the polyfunctional amide compound used in the present invention has at least two carbonyl groups at close positions, it is easily excited directly by light, as shown in the following formula (10). Then, photodimerization proceeds and an auxiliary effect of crosslinking is exhibited. For this reason, it is considered that the curing performance higher than before is expressed.

  As described above, the liquid composition of the present invention has a plurality of factors that can exhibit high curing performance, and since these act synergistically, the liquid composition of the present invention exhibits specifically high curing performance compared to the conventional one. The inventors have speculated.

  Next, the present invention will be described more specifically with reference to examples and comparative examples of the present invention.

<Curable material>
A polyfunctional amide compound and a polyfunctional azide compound were used in the combinations and mass ratios shown in Table 1 below, and set as curable substance sets 1 to 8, respectively. Moreover, comparative curable substance sets 1 to 5 were obtained with combinations and mass ratios shown in Table 2 below.

<Preparation of liquid composition>
A liquid composition was prepared as follows using the curable substance sets 1 to 8 and the comparative curable substance sets 1 to 5 based on the combination of the above compounds. First, a cyan pigment dispersion was prepared as follows. As a pigment, C.I. I. Pigment Blue 15: 3 was used, and a random polymer of styrene / acrylic acid / ethyl acrylate (weight average molecular weight = 3,500, acid value = 150 mgKOH / g) was used as a dispersant. These were dispersed by a bead mill to obtain a cyan pigment dispersion having a pigment solid content of 10% by mass, a P / B ratio (mass ratio of pigment and binder) of 3: 1 and an average particle size of 120 nm. Next, after mixing each component shown in Table 3 and stirring sufficiently, pressure filtration was performed using a filter having a pore size of 0.50 μm, and each active energy ray of Examples 1 to 9 and Comparative Examples 1 to 5 was used. A curable liquid composition (cyan ink form) was mixed and prepared. In addition, the above-mentioned compound [A] or [B] was used for the polymerization initiator. In the present invention, the average particle size of the pigment was measured using a laser light scattering type particle size measuring device.

<Characteristic evaluation>
Evaluations were made regarding the curing performance, ejection stability, and storage stability of the image by each liquid composition.
(Image formation)
First, as an image forming apparatus, an ink jet recording apparatus PIXUS550i (manufactured by Canon) equipped with an ink jet recording head that ejects ink by applying thermal energy according to a recording signal to the ink was prepared. The recording apparatus is modified so that active energy rays can be irradiated. Specifically, a UV lamp that excites a mercury lamp with no electrode from the outside using a microwave is mounted on a portion adjacent to the recording head portion. The UV lamp used a D bulb. The intensity at the irradiation position was 1,500 mW / cm ² . Using this ink jet recording apparatus, evaluation was performed according to the evaluation methods and evaluation criteria described in the following (1) to (3).

(1) Curing performance evaluation (1) -1: Fixability Using Examples 1 to 9 and Comparative Examples 1 to 5 and the inkjet recording apparatus, recording duty was set on offset recording paper OK Kanto (manufactured by Mitsubishi Paper Industries). A solid image with 100% was formed. Under the above-mentioned irradiation conditions, ultraviolet rays were irradiated after recording to obtain a coating film (image). Ten minutes after the formation of the coating film, the Sylbon paper was placed on the coating film (image), and the Sylbon paper was pulled with a load of 100 g / cm ² . Evaluation was performed by visually observing whether or not the recording portion was smudged by rubbing of the recording portion on the non-recording portion (white background portion) and the Sylbon paper of the recording medium. The evaluation criteria for fixability are as follows. The evaluation results are shown in Table 4.
A: The area where no stain due to rubbing is seen is 100% of the area of the Sylbon paper.
B: 90% or more and less than 100% of the area of the Sylbon paper in which no stain due to rubbing is observed.
C: The area where no stain due to rubbing is observed is 20% or more and less than 90% in the area of the Sylbon paper.
D: The area where no stain due to rubbing is seen is less than 20% of the area of the Sylbon paper.

(1) -2: Marker resistance Using Examples 1 to 9, Comparative Examples 1 to 5, and the inkjet recording apparatus, 12-point characters were recorded on PPC paper (manufactured by Canon) under the same conditions as described above. did. After 10 minutes of recording, using a fluorescent pen spot light yellow (manufactured by Pilot), the character portion was marked (overwritten) 10 times with normal writing pressure, and the presence or absence of character disturbance was visually observed and evaluated. . The evaluation criteria for marker resistance are as follows. The evaluation results are shown in Table 4.
A: Characters are not disturbed by the marker when the mark is 10 times or more.
B: Characters are not disturbed by the marker with 2 to 9 marks.
C: Character disturbance due to the marker occurs at one mark.
D: Character disturbance due to the marker occurs significantly with one mark.

(2) Evaluation of ejection stability Using Examples 1 to 9 and Comparative Examples 1 to 5 and the inkjet recording apparatus, horizontal ruled lines are continuously recorded on PPC paper (made by Canon) under the same conditions as described above. did. Thereafter, the thickness of the ruled line and the landing position of the dots were visually observed for evaluation. The evaluation criteria for ejection stability are as follows. The evaluation results are shown in Table 4.
A: There is no change in the thickness of the line, and there is no shift in the landing position.
B: There is a slight change in the thickness of the line, but this is an acceptable level.
C: The change of the line is clear and the deviation of the landing position is also seen.

(3) Storage stability evaluation Examples 1 to 9 and Comparative Examples 1 to 5 were put in a Teflon (registered trademark) container and sealed. This was stored in an oven at 60 ° C. in the dark for 1 month, and the average particle diameter of the pigment before and after storage was compared. The evaluation criteria for storage stability are as follows. The evaluation results are shown in Table 4.
A: The change rate of the average particle diameter is within ± 10%.
B: The rate of change of the average particle diameter exceeds ± 10% and is within ± 15%.
C: Change rate of average particle diameter exceeds ± 15%.

  When each of the liquid compositions of Comparative Examples 1 to 5 was used, there was a partial change in landing position at the time of ejection and a large change in dispersibility after storage. Moreover, all were inferior in the curing performance compared with the Example.

<Evaluation of each color ink set>
Finally, each color ink set was evaluated for curing performance, ejection stability, and storage stability.

  A yellow pigment dispersion and a magenta pigment dispersion were prepared as described below in the same manner as the preparation of the cyan pigment dispersion used in Examples 1 to 9. First, C.I. I. A yellow pigment dispersion having a pigment solid content of 10% by mass, a P / B ratio of 3: 1, and an average particle diameter of 130 nm was prepared in the same manner as that for preparing a cyan pigment dispersion, except that CI Pigment Yellow 13 was used. did. In addition, C.I. I. A magenta pigment dispersion having a pigment solid content of 10% by mass, a P / B ratio of 3: 1, and an average particle diameter of 125 nm was prepared in the same manner as the preparation of the cyan pigment dispersion except that CI Pigment Red 122 was used. did.

  Next, using each pigment dispersion, yellow ink (Example 1Y) and magenta ink (Example 1M) were prepared by the same process and composition as in Example 1 above.

  In addition to the yellow ink and magenta ink obtained above, the cyan ink of Example 1 was combined to form an ink set. Using this ink set, an image was recorded on offset recording paper OK Kanto (manufactured by Mitsubishi Paper Industries) using the same ink jet recording apparatus used in the above evaluation. Specifically, a solid image in which the recording duty of yellow and magenta is 100% respectively, and a solid image in which yellow and magenta are alternately recorded 50% at every other pixel and the total recording duty is 100% ( Secondary color red) was recorded. The yellow, magenta, and red portions of the image thus formed were evaluated for fixability and marker resistance by the same method and evaluation criteria as described above. In addition, for the yellow ink of Example 1Y and the magenta ink of Example 1M, the ejection stability and the storage stability were evaluated by the same method and evaluation criteria as in Examples 1-9. The evaluation results are shown in Table 5.

Claims (10)

A liquid composition containing at least a curable substance and cured by irradiation with active energy rays,
The curable substance is at least one selected from the group consisting of a polyfunctional amide compound represented by the following general formula (1) and a polyfunctional amide compound represented by the following general formula (2), and the following general A liquid composition comprising a polyfunctional azide compound represented by the formula (3):

(In general formula (1), R ₁ represents an n-valent organic group. R ₂ represents a hydrogen atom or a monovalent organic group. R ₃ , R ₄ , and R ₅ are each independently a hydrogen atom, A monovalent organic group or a monovalent organic group containing one carbonyl group at the α-position or β-position of the carbon-carbon double bond in the structure, provided that R ₃ , R ₄ , and R ₅ (At least one is a monovalent organic group containing one carbonyl group at the α-position or β-position of the carbon-carbon double bond in the structure. N represents an integer of 2 or more.)

(In General Formula (2), R ₁ represents an n-valent organic group. R ₆ and R ₇ each independently represents a hydrogen atom or a monovalent organic group. N represents an integer of 2 or more.)

(In General Formula (3), R ₁₂ represents a hydrogen atom or a monovalent organic group. R ₁₃ represents an m-valent organic group. M represents an integer of 2 or more.) R ₁ in the general formula (1) or (2) is selected from the group consisting of a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a hydroxyl group, an ether group, and an amide group. The liquid composition according to claim 1, which is an organic group having at least one hydrophilic group. R ₁₂ in the general formula (3) is at least one selected from the group consisting of a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a hydroxyl group, an ether group, and an amide group. The liquid composition according to claim 1, wherein the liquid composition is an organic group having a hydrophilic group. The liquid composition according to any one of claims 1 to 3, wherein the polyfunctional azide compound represented by the general formula (3) is a polyfunctional azide compound represented by the following general formula (4).

(In General Formula (4), each R ₁₄ independently represents a hydrogen atom, a monovalent organic group, or an alkylene chain in which each R ₁₄ in the structure forms a ring. X independently represents Na, K, Represents a monovalent metal atom selected from Li)   Furthermore, the liquid composition of any one of Claims 1 thru | or 4 which contains a photoradical generator as a polymerization initiator.   The polymerization initiator has at least one hydrophilic group selected from the group consisting of a hydroxyl group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, an ether group, and an amide group. Item 6. The liquid composition according to Item 5.   Furthermore, the liquid composition of any one of Claims 1 thru | or 6 containing a coloring material.   The liquid composition according to claim 1, wherein the liquid composition is for inkjet.   A step of ejecting the liquid composition according to claim 8 from an ink jet recording head and applying the liquid composition to a recording medium, and irradiating the recording medium to which the liquid composition has been applied with active energy rays to form the liquid composition An ink jet recording method comprising a curing step.   An ink jet recording head for applying the liquid composition according to claim 8 to a recording medium, and means for irradiating the liquid composition applied to the recording medium with active energy rays. An ink jet recording apparatus.