JP2016147974A - Composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition exhibiting excellent storage stability when the composition is prepared into an inkjet composition.SOLUTION: The composition comprises a pigment and a pigment dispersant and has such properties that a mixture solution prepared by mixing the composition with water by a mass ratio of 1:1 and left to stand for 24 hours at normal temperature shows an absorbance (ABS) in a water layer thereof of 5% or less with respect to the absorbance (ABS) of the composition. The above composition is to be used for a radiation-curable inkjet composition comprising a polymerizable compound.SELECTED DRAWING: None

Description

  The present invention relates to a composition.

  Ink jet recording ink is capable of recording high-definition images with a relatively simple device, and has rapidly developed in various fields. Among them, various studies have been made on obtaining a more stable and high-quality recorded matter.

  For example, Patent Document 1 describes excellent emission stability and decap resistance in an ink jet printer, excellent character quality of a formed image, resistance to show through, and scratch resistance, and excellent curl characteristics of a printed recording material. For the purpose of providing an inkjet ink, an inkjet ink containing at least a coloring material, an organic solvent, water and a polymer compound, wherein the water content is 10% by mass or more and 50% by mass of the total ink mass %, And at least one of the organic solvents is a water-soluble organic solvent having an SP value of 9.0 or more and less than 12.0, and the water-solubility having an SP value of 9.0 or more and less than 12.0. The content of the organic solvent is 30% by mass or more of the total ink mass, and the polymer compound has a plurality of side chains in the hydrophilic main chain, and the active energy rays are irradiated between the side chains. Cross-linking Inkjet ink is disclosed, which is a case capable polymer.

JP 2007-91910 A

  However, the conventional inkjet composition as described in Patent Document 1 cannot be said to have excellent viscosity stability due to the absorption of moisture in the air.

  Then, an object of this invention is to provide the composition excellent in the storage stability when it was set as the inkjet composition.

  As a result of intensive investigations to solve the above-described problems of the prior art, the present inventors have found that an ink composition having an absorbance measured in a specific range after a specific treatment is performed on the pigment dispersion contained in the composition. It has been found that the above-mentioned problems can be solved by using a product, and the present invention has been completed.

That is, the present invention is as follows.
[1]
A composition comprising a pigment and a pigment dispersant,
The absorbance (ABS) of the aqueous layer after leaving the mixture obtained by mixing the composition and water at a mass ratio of 1: 1 at room temperature for 24 hours is 5 with respect to the absorbance (ABS) of the composition. % Or less,
The said composition is a composition used for the radiation-curable inkjet composition containing a polymeric compound.
[2]
The composition according to [1], wherein the polymerizable compound includes a hydroxyl group-containing monomer.
[3]
The radiation curable inkjet composition according to [2], wherein the hydroxyl group-containing monomer is contained in an amount of 3% by mass to 30% by mass with respect to 100% by mass of the radiation curable inkjet composition.
[4]
The composition according to any one of [1] to [3], wherein the content of water in the composition is 3% by mass or less.
[5]
The radiation curable inkjet composition according to any one of [1] to [4], wherein water is contained in an amount of 0.01% by mass to 1% by mass with respect to 100% by mass of the radiation curable inkjet composition. .
[6]
The composition according to any one of [1] to [5], wherein the acid value of the pigment dispersant is 5 mgKOH / g or less.
[7]
The composition according to any one of [1] to [6], wherein the composition contains 10% by mass to 70% by mass of a pigment with respect to 100% by mass of the composition.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified within the scope of the gist. In the present specification, “(meth) acrylate” means both acrylate and the corresponding methacrylate. “(Meth) acrylic acid” means both acrylic acid and methacrylic acid corresponding thereto.

〔Composition〕
The composition of this embodiment contains a pigment and a pigment dispersant. The absorbance (ABS) of the aqueous layer after leaving the mixture obtained by mixing the composition and water at a mass ratio of 1: 1 at room temperature for 24 hours is 5 with respect to the absorbance (ABS) of the composition. % Or less. Moreover, the said composition is used for the radiation curable inkjet composition containing a polymeric compound. The radiation curable ink jet composition is preferably a radical polymerization type composition from the viewpoint of further improving the curability and from the viewpoint of obtaining high versatility and high simplicity.

  The composition of the present embodiment may be used as it is as a radiation curable inkjet composition or may be used as a pigment dispersion contained in the radiation curable inkjet composition. In addition, when the composition of this embodiment is used as a pigment dispersion contained in a radiation curable inkjet composition, the radiation curable inkjet composition has a configuration (for example, It is not necessary to have the absorbance in the specific range described above. The pigment dispersion as used herein refers to a liquid in which a pigment is dispersed, which contains at least a pigment and a pigment dispersant.

  The absorbance (ABS) of the aqueous layer after leaving the mixture obtained by mixing the composition and water at a mass ratio of 1: 1 at room temperature for 24 hours is 5% with respect to the absorbance (ABS) of the composition. By being below, it becomes possible to obtain the outstanding storage stability. Such a specific composition tends to be incompatible with water and is presumed to have excellent storage stability due to the difficulty of absorbing moisture in the air.

  An inkjet composition can be used for various uses as a composition used by being ejected by an inkjet method, and the use is not limited. Specific uses include ink and polymerization molding. Among these, the ink is preferably used from the viewpoint of more effectively and surely achieving the operational effects of the present invention. Hereinafter, the case where the radiation curable inkjet composition of this embodiment is used as an inkjet recording ink composition (hereinafter also simply referred to as “ink composition”), which is an embodiment of the inkjet composition, will be described in more detail. However, the composition of the present embodiment is not limited to this.

  From the viewpoint of storage stability, the content of water in the inkjet composition of the present embodiment is preferably 3% by mass or less, and preferably 2% by mass or less with respect to 100% by mass of the inkjet composition. More preferably, it is more preferably 1% by mass or less, and particularly preferably 0.003% by mass or less. The lower limit of the water content is not particularly limited, and may be below the detection limit. As the water content, a value obtained by the measurement method carried out in Examples described later can be adopted.

  As a method for adjusting the water content in the composition, for example, each component of the composition, specifically, a method of removing water mixed in the polymerizable compound, a method of removing moisture from the composition, Examples thereof include a method for suppressing the mixing of water during preparation. Among these, as a method of removing water mixed in the polymerizable compound, more specifically, a method of purifying the polymerizable compound by distillation, a method of allowing the polymerizable compound to permeate a semipermeable membrane that selectively permeates water, And a method of selectively adsorbing water mixed in the polymerizable compound to a water adsorbent that adsorbs water. Among these, a distillation purification method is preferable from the viewpoint of more efficiently and reliably reducing the water content.

  The composition of the present embodiment includes a pigment and a pigment dispersant, and the absorbance obtained by a predetermined measurement method is within a predetermined range. Specifically, the absorbance (ABS) of the aqueous layer after leaving a mixture obtained by mixing the composition and water at a mass ratio of 1: 1 in the atmosphere at room temperature for 24 hours is the absorbance of the composition. On the other hand, it is 5% or less, preferably 3% or less, more preferably 1% or less. When the absorbance is 5% or less, excellent storage stability of the ink composition can be obtained. More specifically, the measurement method implemented in the examples described later is employed as the predetermined measurement method.

  In order to obtain the absorbance as described above, specifically, as a pigment dispersant described later contained in the composition, a pigment dispersant having an acid value and an amine value within a specific range is used. For example, a pigment dispersant having little or no hydrophilic group may be used.

  The composition of the present embodiment is preferably a non-aqueous composition from the viewpoint of coating film hardness and curability and simplification of the dehydration purification process. More specifically, the water content in the composition is more preferably 3% by mass or less, further preferably 0.01% by mass or more and 2% by mass or less, and 0.05% by mass or more. It is more preferably 1% by mass or less, still more preferably 0.1% by mass or more and 1% by mass or less, and particularly preferably 0.2% by mass or more and 1% by mass or less. In order to obtain a non-aqueous composition, a method using a pigment and a pigment dispersant in which mixing of moisture is suppressed may be employed. The amount of water can be measured by the same method as the measurement method for the compositions carried out in the examples described later.

  It is preferable that the composition of this embodiment contains the polymeric compound mentioned later other than a pigment and a pigment dispersant. By including the polymerizable compound, the compatibility with the pigment dispersant is excellent, and the pigment dispersion tends to be easily adjusted to a viscosity that can be discharged by an inkjet head. When the composition contains a polymerizable compound, the polymerizable compound is more preferably contained in an amount of 10% by mass to 90% by mass and more preferably 20% by mass to 60% by mass with respect to 100% by mass of the pigment dispersion. More preferably. When the content of the polymerizable compound is 10% by mass or more, the pigment dispersant tends to be easily compatible, and when it is 90% by mass or less, the storage stability of the ink tends to be superior. is there.

<Pigment>
As a pigment of this embodiment, an inorganic pigment and an organic pigment are mentioned, for example.

  Specific examples of the inorganic pigments include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide.

  Specific examples of organic pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ansanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments. And diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

  Further, the pigment of the present embodiment may be a self-dispersing pigment and / or a polymer dispersing pigment.

The self-dispersing pigment is a pigment having a hydrophilic group on its surface. As the hydrophilic group, -OM, -COOM, -CO -, - SO 3 M, -SO 2 M, -SO 2 NH 2, -RSO 2 M, -PO 3 HM, -PO 3 M 2, -SO 2 It is preferably at least one hydrophilic group selected from the group consisting of NHCOR, —NH ₃ , and —NR ₃ .

  In these chemical formulas, M represents a hydrogen atom, an alkali metal, ammonium, an optionally substituted phenyl group, or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms or a substituted group. A naphthyl group which may have a group is represented. The above M and R are selected independently of each other.

  Specifically, the self-dispersion pigment is produced by subjecting the pigment to physical treatment and / or chemical treatment to bond (graft) the hydrophilic group to the surface of the pigment. Specific examples of the physical treatment include vacuum plasma treatment. Further, as the chemical treatment, specifically, a wet oxidation method in which oxidation is performed with an oxidizing agent in water, a method in which p-aminobenzoic acid is bonded to the pigment surface to bond a carboxyl group via a phenyl group, and the like can be mentioned. It is done.

  The polymer-dispersed pigment is a pigment that can be dispersed in a liquid by a polymer. The polymer content relative to the pigment can be expressed as the coverage of the polymer that coats the pigment. The polymer coverage is preferably 1% to 50%, more preferably 1% to 10%, and even more preferably 1% to 5%. When the coverage is 1% or more, the dispersibility tends to be good. Further, when the coverage is 50% or less, the color developability tends to be further improved, and when it is 5% or less, the color developability tends to be even better.

  As the above polymer, a polymer obtained by copolymerization of (meth) acrylate and (meth) acrylic acid is preferably 70% by mass or more of the constituent components. Thereby, it tends to be further excellent in the fixing property and glossiness of the ink. Moreover, it is more preferable that at least one of the alkyl (meth) acrylate having 1 to 24 carbon atoms and the cyclic alkyl (meth) acrylate having 3 to 24 carbon atoms is polymerized from a monomer component of 70% by mass or more. Specifically, as the monomer component, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl ( (Meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate Cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetramethylpiperidyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dis Ropenteniru (meth) acrylate, dicyclopentenyloxy (meth) acrylate, and behenyl (meth) acrylate. In addition, as other monomer components for polymerization, hydroxy (meth) acrylate having a hydroxyl group such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, urethane (meth) acrylate, epoxy (meth) ) Acrylate and the like.

  The content of the pigment in the composition is preferably 10% by mass or more and 70% by mass or less, more preferably 20% by mass or more and 65% by mass or less, with respect to 100% by mass of the composition. More preferably, it is at least 60% by mass. When the pigment content is 10% by mass or more, the color developability of the recorded product tends to be better. Moreover, it exists in the tendency for the dispersibility of the pigment in a composition to become more favorable because content of a pigment is 70 mass% or less.

<Pigment dispersant>
The composition of this embodiment contains a pigment dispersant. Examples of the pigment dispersant include a pigment dispersant made of a resin. Examples of the resin include (meth) acrylic resins, urethane resins, polyamine resins, and polyether resins. As a commercial item, the dispersic series by BYKChemie, etc. are mentioned. From the viewpoint of making the pigment dispersibility better, the pigment dispersion may further contain one or more pigment dispersants.

  The acid value of the pigment dispersant of the present embodiment is preferably 5 mgKOH / g or less, more preferably 3 mgKOH / g or less, and further preferably 1 mgKOH / g or less from the viewpoint of storage stability. .

  From the viewpoint of storage stability, the amine value of the pigment dispersant of this embodiment is preferably 0 mgKOH / g or more and 90 mgKOH / g or less, more preferably 0 mgKOH / g or more and 80 mgKOH / g or less, and 0 mgKOH / g or less. g is more preferably 60 mgKOH / g or less, particularly preferably 0 mgKOH / g or more and 50 mgKOH / g or less, and particularly preferably 0 mgKOH / g or more and 40 mgKOH / g or less.

  In order to obtain the acid value and amine value within the above ranges, specifically, (meth) acrylic resins, urethane resins, polyamine resins, polyether resins, and the like can be used as the resin for the pigment dispersant. For example, DISPERBYK-2152, DISPERBYK-2013, DISPERBYK-118, DISPERBYK-108, BYK-9076, or the like may be used.

  The acid value and amine value of the pigment dispersant are determined by potentiometric titration. A plurality of types of pigment dispersants may be added to the composition. In this case, it is preferable that the acid value and amine value of each pigment dispersant satisfy the above-mentioned range.

  The pigment dispersant in the composition is preferably 10% by mass to 70% by mass, more preferably 20% by mass to 65% by mass, and more preferably 30% by mass with respect to 100% by mass of the composition. It is more preferable that the content is not less than 60% and not more than 60% by mass. When the pigment dispersant is 10% by mass or more, the dispersibility of the pigment tends to be good. Moreover, it exists in the tendency for color development to become favorable because a pigment dispersant is 70 mass% or less.

<Polymerizable compound>
The inkjet composition of this embodiment contains a polymerizable compound. The polymerizable compound can be polymerized by applying energy of radiation such as light irradiation alone or by the action of a polymerization initiator to cure the composition on the recording medium.

  Specific examples of the polymerizable compound include monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers and oligomers. A polymeric compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polymerizable compound preferably contains a radical polymerizable compound from the viewpoint of further improving the curability of the inkjet composition and from the viewpoint of obtaining high versatility and high simplicity. In addition to or in place of it, the polymerizable compound increases the curability, further lowers the viscosity of the inkjet composition, and increases the solubility of the polymerization initiator when a polymerization initiator is used. And a polymerizable compound having a (meth) acrylate group. The polymerizable compound having a vinyl ether group and a (meth) acrylate group is preferably a radical polymerizable compound having a vinyl ether group and a (meth) acrylate group. Examples of such a polymerizable compound include (meth) acrylates having a monofunctional or polyfunctional vinyl ether group, and these are preferable from the same viewpoint as described above.

Although the monofunctional (meth) acrylate having a vinyl ether group is not particularly limited, the following general formula (1) can be used from the viewpoint of lowering the viscosity of the composition, having a high flash point, and further improving the curability of the inkjet composition. ):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3 ··· (1)
It is preferable that the (meth) acrylic acid ester which has the vinyl ether group represented by these is included. Here, in formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or having 1 to 11 carbon atoms. It is a monovalent organic residue.

  Specific examples of (meth) acrylic acid esters having a vinyl ether group represented by the general formula (1) include 2-vinyloxyethyl (meth) acrylate, 3-vinyloxypropyl (meth) acrylate, (meth ) 1-methyl-2-vinyloxyethyl acrylate, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, 1-methyl-3-vinyloxypropyl (meth) acrylate, (meth) acryl 1-vinyloxymethylpropyl acid, 2-methyl-3-vinyloxypropyl (meth) acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, (meth) 1-methyl-2-vinyloxypropyl acrylate, 2-vinyloxybutyl (meth) acrylate, (meth ) 4-vinyloxycyclohexyl acrylate, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, 3-vinyloxymethylcyclohexylmethyl (meth) acrylate, (meth) acryl 2-vinyloxymethylcyclohexylmethyl acid, p-vinyloxymethylphenylmethyl (meth) acrylate, m-vinyloxymethylphenylmethyl (meth) acrylate, o-vinyloxymethylphenylmethyl (meth) acrylate, (meth ) 2- (vinyloxyethoxy) ethyl acrylate, 2- (vinyloxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxy) propyl (meth) acrylate, 2- (vinyl) (meth) acrylate Loxyethoxy) isopropyl, (meth) acrylic 2- (vinyloxyisopropoxy) propyl, (meth) acrylic acid 2- (vinyloxyisopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (vinyloxy) Ethoxyisopropoxy) ethyl, 2- (vinyloxyisopropoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxy) (meth) acrylate Ethoxy) propyl, (meth) acrylic acid 2- (vinyloxyethoxyisopropoxy) propyl, (meth) acrylic acid 2- (vinyloxyisopropoxyethoxy) propyl, (meth) acrylic acid 2- (vinyloxyisopropoxyisopropoxy) ) Propyl, (meth) acrylic acid 2- ( Vinyloxyethoxyethoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyethoxyisopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyisopropoxyethoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyiso) Examples include propoxyisopropoxy) isopropyl, 2- (vinyloxyethoxyethoxyethoxy) ethyl (meth) acrylate and 2- (vinyloxyethoxyethoxyethoxyethoxy) ethyl (meth) acrylate. These are used singly or in combination of two or more.

  Among these, from the same viewpoint as described above, 2- (vinyloxyethoxy) ethyl (meth) acrylate, that is, 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate At least one of them is preferable, and 2- (vinyloxyethoxy) ethyl acrylate is more preferable. Since both 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate have a simple structure and a small molecular weight, the viscosity of the inkjet composition can be significantly reduced. Examples of 2- (vinyloxyethoxy) ethyl (meth) acrylate include 2- (2-vinyloxyethoxy) ethyl (meth) acrylate and 2- (1-vinyloxyethoxy) ethyl (meth) acrylate. Examples of 2- (vinyloxyethoxy) ethyl acrylate include 2- (2-vinyloxyethoxy) ethyl acrylate and 2- (1-vinyloxyethoxy) ethyl acrylate. Incidentally, 2- (vinyloxyethoxy) ethyl acrylate is superior in terms of curability compared to 2- (vinyloxyethoxy) ethyl methacrylate.

  The content of the polymerizable compound having a vinyl ether group and a (meth) acrylate group in the inkjet composition is preferably 10% by mass or more and 70% by mass or less based on the total amount (100% by mass) of the inkjet composition. 10 mass% or more and 60 mass% or less are more preferable, and 10 mass% or more and 50 mass% or less are more preferable. When the content is 10% by mass or more, the viscosity of the composition can be reduced, and the curability of the inkjet composition tends to be more excellent. On the other hand, when the content is 70% by mass or less, the ink composition is excellent in storage stability and tends to be excellent in the surface gloss of the printed matter.

  The ink jet composition may contain one or more monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers other than those exemplified above. Specific examples of such monomers include unsaturated carboxylic acids of (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid; salts of the unsaturated carboxylic acids; esters of unsaturated carboxylic acids, urethanes , Amides and anhydrides; acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.

  As monofunctional, bifunctional, and trifunctional or higher polyfunctional oligomers, specifically, oligomers formed from the above monomers such as linear acrylic oligomers, epoxy (meth) acrylates, oxetane (meth) acrylates, fats Group urethane (meth) acrylate, aromatic urethane (meth) acrylate and polyester (meth) acrylate.

  Moreover, an N-vinyl compound may be included as another monofunctional monomer or polyfunctional monomer. Specific examples of the N-vinyl compound include N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, and derivatives thereof.

  The ink jet composition may contain a monofunctional (meth) acrylate as a monofunctional monomer. In this case, the viscosity of the ink jet composition becomes lower, the solubility of the photopolymerization initiator and other additives is excellent, and the ejection stability during ink jet recording is easily obtained. Specific examples of monofunctional (meth) acrylates include isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isomristyl (meth) acrylate, Isostearyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, Methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, phenoxyethyl (meth ) Acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, lactone modified Flexible (meth) acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, 2- (isopropenoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxyethoxy) Kishietokishi) ethyl (meth) acrylate, polyethylene glycol monovinyl ether (meth) acrylate, and polypropylene glycol monovinyl ether (meth) acrylate and the like. Among these, 4-hydroxybutyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferable.

  The content of the monofunctional monomer in the inkjet composition is preferably 10% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 50% by mass or less with respect to the total amount (100% by mass) of the inkjet composition. preferable. By setting it as the said preferable range, it exists in the tendency which is excellent with sclerosis | hardenability, initiator solubility, storage stability, and discharge stability. When the monofunctional monomer is contained in the pigment dispersion, the content of the monofunctional monomer is more than 10% by mass and less than 90% by mass with respect to the total amount (100% by mass) of the pigment dispersion. Preferably, 20 mass% or more and 60 mass% or less are more preferable. When the content of the monofunctional monomer is 10% by mass or more, the viscosity of the ink composition tends to be suppressed, and when it is 90% by mass or less, the storage stability of the ink composition tends to be excellent. is there.

  The inkjet composition may include a polyfunctional (meth) acrylate as a polyfunctional monomer. Among them, as the bifunctional (meth) acrylate, specifically, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, Tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) ) Acrylate, neopentyl glycol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, EO (ethylene oxide) adduct of bisphenol A di (meth) acrylate, bisphenol PO (propylene oxide) adducts of di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol di (meth) ) Acrylates.

  Further, as tri- or higher functional (meth) acrylate, specifically, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxytri (meth) acrylate, cowprolactone modified trimethylolpropane tri (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate And caprolactam-modified dipentaerythritol hexa (meth) acrylate.

  Among these, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and pentaerythritol tri (meth) acrylate are preferable. More preferred are propylene glycol di (meth) acrylate and pentaerythritol tri (meth) acrylate.

  The content of the polyfunctional monomer in the inkjet composition is preferably 5% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 50% by mass or less with respect to the total amount (100% by mass) of the inkjet composition. 15 mass% or more and 40 mass% or less are still more preferable. By setting it as the said preferable range, it exists in the tendency which is excellent with sclerosis | hardenability, storage stability, discharge stability, and the surface gloss of printed matter.

  The polymerizable compound preferably contains a hydroxyl group-containing monomer, which is a monomer containing a hydroxyl group, from the viewpoint of obtaining excellent coating film hardness. The inkjet composition preferably contains the hydroxyl group-containing monomer in an amount of 3% by mass to 30% by mass and more preferably 5% by mass to 20% by mass with respect to the total amount (100% by mass) of the inkjet composition. Preferably, it is more preferably 7% by mass or more and 15% by mass or less. When the composition contains 3% by mass or more of the hydroxyl group-containing monomer, the coating film hardness tends to be excellent, and when it contains 30% by mass or less, the hygroscopicity of the inkjet composition tends to be suppressed.

  Among the monofunctional monomers and polyfunctional monomers containing a hydroxyl group mentioned as the polymerizable compound, 4-hydroxybutyl acrylate is preferable as the hydroxyl group-containing monomer.

  In addition, from the viewpoint of enhancing the toughness, heat resistance, and chemical resistance of the cured film, it is also preferable to use a monofunctional (meth) acrylate and a bifunctional (meth) acrylate, and among them, phenoxyethyl (meth) acrylate and dipropylene. It is more preferable to use glycol di (meth) acrylate together.

  35 mass% or more and 95 mass% are preferable with respect to the whole quantity (100 mass%) of the inkjet composition, and, as for content of the polymeric compound in an inkjet composition, 45 mass% or more and 90 mass% or less are more preferable. When the content of the polymerizable compound is within the above range, the viscosity and odor can be further reduced, and the solubility and reactivity of the photopolymerization initiator and the surface gloss of the printed material should be further improved. Can do.

<Polymerization initiator>
The inkjet composition of this embodiment may contain a polymerization initiator. The polymerization initiator is not limited as long as it generates active species such as radicals, cations, and anions by the energy of radiation such as ultraviolet rays and electron beams, and initiates the polymerization of the polymerizable compound. An agent is preferred, and a radical photopolymerization initiator is preferred. As the radical photopolymerization initiator, acylphosphine oxide photopolymerization initiators and thioxanthone photopolymerization initiators are more preferable, and acylphosphine oxide photopolymerization initiators are more preferable.

  Acylphosphine oxide photopolymerization initiators are susceptible to oxygen inhibition, but are suitable for curing with long wavelength LEDs. Further, the acylphosphine oxide photopolymerization initiator can be dissolved more favorably in the composition when the water content in the composition is 1.0% by mass or less with respect to the total amount of the composition.

  Specific examples of the acylphosphine oxide photopolymerization initiator include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and bis- (2, 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide. As a commercially available product of the acylphosphine oxide photopolymerization initiator, specifically, IRGACURE 819 (trade name, manufactured by BASF, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide), SPEEDCURE TPO (manufactured by Lambson) Trade name, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) and DAROCUR TPO (trade name, manufactured by BASF, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), SPEEDCURE TPO-L (made by Lambson) Trade name, ethyl- (2,4,6-trimethylbenzoyl) phenylphosphine oxide) and the like.

  The content of the acylphosphine oxide photopolymerization initiator in the inkjet composition is preferably 3.0% by mass or more and 20% by mass or less with respect to the total amount (100% by mass) of the inkjet composition. When the content is 3.0% by mass or more, the curability tends to be more excellent. From the same viewpoint, the content of the acylphosphine oxide photopolymerization initiator is more preferably 4.0% by mass or more, and further preferably 7.0% by mass or more. Further, when the content is 20% by mass or less, the dissolution and storage stability of the solid content is favorably maintained, and the reliability tends to be excellent. From the same viewpoint, the acylphosphine oxide photopolymerization initiator is more preferably 15% by mass or less, and further preferably 13% by mass or less.

  By including the thioxanthone photopolymerization initiator in the ink jet composition, the surface tackiness can be reduced, and in particular, the ink surface can be cured in the case of a thin film that is susceptible to oxygen inhibition, thereby preventing color mixing and bleeding between dots. Further, it is preferable to use both an acylphosphine oxide photopolymerization initiator and a thioxanthone photopolymerization initiator because they are more excellent in the curing process by UV-LED and the curability and adhesion of the ink jet composition tend to be further improved.

  The thioxanthone photopolymerization initiator preferably contains one or more selected from the group consisting of thioxanthone, diethylthioxanthone, isopropylthioxanthone, and chlorothioxanthone. Further, as diethylthioxanthone, 2,4-diethylthioxanthone, as isopropylthioxanthone, 2-isopropylthioxanthone, and as chlorothioxanthone, 2-chlorothioxanthone is more preferable. An inkjet composition containing such a thioxanthone photopolymerization initiator tends to be more excellent in curability, storage stability, and ejection stability. Among these, a thioxanthone photopolymerization initiator containing diethyl thioxanthone is more preferable. By including diethylthioxanthone, there is a tendency that a wide range of ultraviolet light (UV light) can be converted into active species more efficiently.

  Specific examples of commercially available thioxanthone photopolymerization initiators include Speedcure DETX (2,4-diethylthioxanthone), Speedcure ITX (2-isopropylthioxanthone), Speedcure CTX (2-chlorothioxanthone), SPEEDCURE CPTX (1-chloro -4-propylthioxanthone (manufactured by Lambson), KAYACURE DETX (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.), and the like.

  The content of the thioxanthone photopolymerization initiator in the inkjet composition is preferably 0.5% by mass or more and 5.0% by mass or less, and 1.0% by mass with respect to the total amount (100% by mass) of the inkjet composition. More preferably, it is 4.0 mass% or less. When the content is 0.5% by mass or more, the surface tackiness can be further reduced, the ink surface can be cured in a thin film that is susceptible to oxygen inhibition, and color mixing and bleeding between dots can be further prevented. There is a tendency. Further, when the content is 5.0% by mass or less, there is little coloring of the ink by the initiator itself, there is little yellowing of the hue, and there is a tendency that the adhesiveness of the cured film is more excellent.

  The ink jet composition may further contain one or more of radical photopolymerization initiators or photocationic polymerization initiators other than those described above. Specific examples of photo radical polymerization initiators other than those described above include aromatic ketones, aromatic onium salt compounds, organic peroxides, thio compounds (such as thiophenyl group-containing compounds), α-aminoalkylphenone compounds, hexaaryls. Examples thereof include a rubiimidazole compound, a ketoxime ester compound, a borate compound, an azinium compound, a metallocene compound, an active ester compound, a compound having a carbon halogen bond, and an alkylamine compound.

  As commercial products of photo radical polymerization initiators other than the above, specifically, IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-) Ketone), DAROCUR 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl -1-propan-1-one), IRGACURE 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1- ON}, IRGACURE 907 (2-methyl-1- (4-methylthiophenyl) 2-morpholinopropan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2- [(4-Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), IRGACURE 784 (bis (η5-2,4-cyclopentadien-1-yl) -bis (2 , 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime) )]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9 -Carbazol-3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (2 -Hydroxyethoxy) ethyl ester mixture (above, BASF), Speedcure TPO (above, Lambson), Lucirin TPO, LR8883, LR8970 (above, BASF), Ubekrill P36 (UCB), etc. Can be mentioned.

  Specific examples of other photocationic polymerization initiators include sulfonium salts and iodonium salts.

  The content of the photopolymerization initiator in the inkjet composition is preferably 5% by mass or more and 20% by mass or less with respect to the total amount (100% by mass) of the inkjet composition. When the content is within the range, the ultraviolet curing rate can be sufficiently exerted, and the undissolved residue of the photopolymerization initiator and the color derived from the photopolymerization initiator tend to be avoided.

<Polymerization inhibitor>
The ink jet composition may contain one or more polymerization inhibitors from the viewpoint of further improving the storage stability. Specific examples of the polymerization inhibitor include a compound having a 2,2,6,6-tetramethylpiperidine-N-oxyl skeleton, a compound having a 2,2,6,6-tetramethylpiperidine skeleton, Hindered amine compounds such as compounds having 6,6-tetramethylpiperidine-N-alkyl skeleton and compounds having 2,2,6,6-tetramethylpiperidine-N-acyl skeleton; p-methoxyphenol, hydroquinone monomethyl ether ( MEHQ), hydroquinone, cresol, t-butylcatechol, 3,5-di-t-butyl-4-hydroxytoluene, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'- Methylene bis (4-ethyl-6-butylphenol), as well as 4,4′-thiobis (3-methyl-6-tert-butyl) Phenol) and the like. Commercially available products include LA-7RD (trade name, manufactured by ADEKA, a compound having a 2,2,6,6-tetramethylpiperidine-1-oxyl skeleton) and the like.

[Other ingredients]
The composition and inkjet composition of the present embodiment may contain any component that can be used in a conventional radiation-curable inkjet ink composition in addition to the above-described components. As such optional components, specifically, coloring materials such as dyes, surfactants, penetrants, moisturizers, dissolution aids, viscosity modifiers, pH adjusters, antioxidants, antiseptics, antifungal agents , Corrosion inhibitors, chelating agents for capturing metal ions that affect dispersion, other additives and solvents, and the like. Each of these is used alone or in combination of two or more.

The ink jet apparatus according to the present embodiment is an apparatus including an ink jet head that uses the above ink jet composition and a container and discharges the ink jet composition by an ink jet method. In addition, the ink jet method of the present embodiment includes a discharge step of discharging the ink jet composition from the ink jet head. The ink jet method according to the present embodiment includes a curing step in which the ink jet composition is ejected onto an ejection target (for example, a recording medium), and the ink jet composition attached to the ejection target is cured by irradiation with ultraviolet rays. You may do it. Moreover, the inkjet apparatus of this embodiment may be provided with the irradiation apparatus used in the said hardening process. In the irradiation step, it is preferable to use a metal halide lamp, a mercury lamp, an ultraviolet light emitting diode, or the like as the ultraviolet light source, and among these, an ultraviolet light emitting diode is more preferable from the viewpoint of miniaturization and power saving. As the ultraviolet light emitting diode, one having an emission peak wavelength preferably in the range of 360 nm or more and 420 nm or less is preferable from the viewpoint of availability. Further, the irradiation energy of ultraviolet rays in the curing step is preferably 100 mJ / cm ² or more and 1000 mJ / cm ² or less, from the viewpoint of sufficiently curing the ink jet composition and the shortening of the curing step, and 200 mJ / cm ^2. above 800 mJ / cm @ 2 or less, and even more preferably 300 mJ / cm ² or more 600 mJ / cm ² or less. The ink jet apparatus and ink jet method of the present embodiment are not particularly limited in configurations other than those described above. For example, as a configuration other than that, a conventionally known configuration may be provided. According to the ink jet recording apparatus and the ink jet recording method of the present embodiment, the ink jet composition not only has excellent curability, but also can suppress the precipitation of foreign matters in the ink jet composition, and therefore has excellent discharge stability. Become. In particular, when the composition contains a polymerizable compound having a vinyl ether group, the storage stability is excellent even though the inkjet composition is cured by irradiation with ultraviolet rays. Furthermore, when the ink jet composition contains a polymerizable compound having a vinyl ether group, the viscosity of the ink jet composition can be reduced, so that discharge stability can be further improved from such a viewpoint.

  Hereinafter, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples and comparative examples as long as the gist thereof is not exceeded.

The main materials for the compositions used in the following examples and comparative examples are as follows.
[Inkjet composition]
(Pigment dispersion)
[Pigment]
Carbon Black (CI Pigment Black 7) (Mitsubishi Chemical Corporation, trade name “MA-100”, also referred to as Pigment Black 7)
(Pigment dispersant)
DISPERBYK-2152 (Brand name manufactured by BYK Chemie, hyperbranched polyester, solventless type)
DISPERBYK-108 (trade name, manufactured by BYK Chemie, pigment affinity group, carboxylic acid ester having a hydroxyl group, solventless type)
DISPERBYK-2013 (trade name, manufactured by BYK Chemie, copolymer having a pigment affinity group, solventless type)
DISPERBYK-180 (trade name manufactured by BYK Chemie, alkylolamine salt of a copolymer containing an acid group, solventless type)
[Polymerizable compound 1]
Phenoxyethyl acrylate (Osaka Organic Chemical Industries, Ltd., abbreviated as PEA)
[Polymerizable compound 2]
2- (2-vinyloxyethoxy) ethyl acrylate (Nippon Shokubai Co., Ltd., abbreviated as VEEA)
Dipropylene glycol diacrylate (manufactured by Sartomer, abbreviated as DPGDA)
4-hydroxybutyl acrylate (Osaka Organic Chemical Industries, Ltd., abbreviated as 4HBA)
(Polymerization initiator)
SPEEDCURE TPO (trade name, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide manufactured by Lambson, abbreviated as TPO)
KAYACURE DETX (Nippon Kayaku Co., Ltd., trade name, 2,4-diethylthioxanthone, abbreviated as DETX)
(Polymerization inhibitor)
LA-7RD (trade name, manufactured by ADEKA, compound having 2,2,6,6-tetramethylpiperidine-1-oxyl skeleton)

[Preparation of dispersion]
Each material was mixed with the composition shown in Table 1 below, and stirred sufficiently to obtain dispersions 1 to 4. In Table 1 below, the numerical unit is mass%, and the total is 100.0 mass%.

(Physical property 1) Absorbance ratio Distilled water was added to 1 g of a sample (collected supernatant or dispersion) and diluted 1000 times. Subsequently, the absorbance (ABS value) at a wavelength of 500 nm of the diluted sample was measured using a spectrophotometer Spectrophotometer U-3300 (manufactured by Hitachi, Ltd.). The absorbance of the pigment dispersion immediately after preparation diluted 1000 times with distilled water and the mixture of water and dispersion mixed at a ratio of 1: 1 are well stirred and allowed to stand in the atmosphere at room temperature for 24 hours. From the absorbance of a solution obtained by diluting the subsequent supernatant (aqueous layer) 1000 times with distilled water, the absorbance ratio was determined using the following formula. For mixing, 300 g of pigment dispersion and pure water were used. The evaluation results are shown in Table 1.
Absorbance ratio (%) = (absorbance of the diluted liquid of the supernatant / absorbance of the diluted liquid of the pigment dispersion) × 100

[Preparation of inkjet composition]
Each material was mixed with the composition shown in Table 2 below, and stirred sufficiently to obtain each inkjet composition. In Table 2 below, the numerical unit is mass%, and the total is 100.0 mass%.

(Evaluation 1) Moisture-absorbing foreign matter The ink-jet composition was allowed to stand for 1 week in an open-air environment at a temperature of 30 ° C. and a relative humidity of 90%. The presence or absence was visually observed. In addition, when the moisture content of the left inkjet composition was measured by the method of Evaluation 3 to be described later, all exceeded 1%. The evaluation results are shown in Table 2.
A: Foreign matter was confirmed.
B: Foreign matter was not confirmed.

(Evaluation 2) Storage stability After accommodating an inkjet composition in a glass bottle, the glass bottle was sealed, left at 60 ° C. for 1 week, and the change in viscosity was observed. Viscosity at 20 ° C. before and after storage was measured with a viscometer manufactured by phisica, and how much the viscosity of the inkjet composition after storage was increased relative to the viscosity of the inkjet composition before storage, that is, what% It was calculated whether the viscosity increased. Based on the results, storage stability was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2.
A: The change in viscosity was less than ± 10%, and the storage stability was good.
B: The viscosity change was ± 10% or more, and the storage stability was not good.

(Evaluation 3) Moisture content The moisture content in the inkjet composition was measured with a Karl Fischer moisture meter MKA-520 (manufactured by Kyoto Electronics Industry Co., Ltd.). The evaluation results are shown in Table 2. The unit of numerical values is mass%.

(Evaluation 4) Coating Film Hardness Using a UV-LED with a peak wavelength of 365 nm, the inkjet composition applied to the substrate (PET film) was irradiated with 200 mJ / cm ² of irradiation energy, and a coating film having a thickness of 9 μm. Was made. About the coating film, the pencil hardness based on JISK5600-5-4 was measured, and it evaluated as coating-film hardness. The evaluation results are shown in Table 2.

  According to the comparison of the examples and comparative examples shown in Table 2, according to the composition according to the present invention, when it is an inkjet composition, excellent storage stability can be obtained, and further the generation of absorbing foreign matter is suppressed, It was found that the moisture content was small and an excellent coating film hardness was obtained.

Claims (7)

A composition comprising a pigment and a pigment dispersant,
The absorbance (ABS) of the aqueous layer after leaving the mixture obtained by mixing the composition and water at a mass ratio of 1: 1 at room temperature for 24 hours is 5 with respect to the absorbance (ABS) of the composition. % Or less,
The said composition is a composition used for the radiation-curable inkjet composition containing a polymeric compound.   The composition according to claim 1, wherein the polymerizable compound contains a hydroxyl group-containing monomer.   3. The composition according to claim 2, wherein the radiation curable inkjet contains 3% by mass to 30% by mass of the hydroxyl group-containing monomer with respect to 100% by mass of the radiation curable inkjet composition.   The composition of any one of Claims 1-3 whose content of the water in the said composition is 3 mass% or less.   5. The composition according to claim 1, wherein the radiation curable ink jet comprises 0.01% by mass to 1% by mass of water with respect to 100% by mass of the radiation curable ink jet composition. .   The composition of any one of Claims 1-5 whose acid value of the said pigment dispersant is 5 mgKOH / g or less.   The said composition is a composition of any one of Claims 1-6 containing 10 mass% or more and 70 mass% or less of pigments with respect to 100 mass% of the compositions.