JP7107293B2 - Inkjet method and inkjet device - Google Patents

Description

The present invention relates to an ultraviolet curable inkjet composition and a container.

The ink jet recording method is capable of recording high-definition images with a relatively simple apparatus, and is rapidly developing in various fields. Among these, various studies have been made on ink compositions used in ink jet recording methods in which the ink is cured by irradiation with ultraviolet rays. For example, Patent Document 1 discloses that at least a pigment, an acid UV-curable inkjet ink containing a high-value dispersant, a polymerizable compound, and a photopolymerization initiator, wherein the total amount of cationic impurities, metal impurities, and strongly acidic substances is 500 ppm or less, and the water content is 1 to 1 An inkjet ink is described which is characterized by 3% by weight.

Japanese Patent Application Laid-Open No. 2005-200560

However, when the water content in the UV-curable inkjet composition is 1 to 3% by mass as in Patent Document 1, the pigment may aggregate to form foreign matter (pigment aggregates). In addition, when the water content in the composition is high, the curability of the ink jet composition may also deteriorate. In order to suppress deposition of foreign matter and improve curability, it is conceivable to reduce the water content in the ultraviolet-curable inkjet composition as much as possible. However, if an attempt is made to excessively reduce the water content, an excessive amount of steps and time are required, particularly for removing the water from the polymerizable compound. sexuality declines.

The present invention has been made to solve at least a part of the above-described problems, and has excellent curability, can suppress the precipitation of foreign substances, has excellent storage stability, and has high production efficiency. An object of the present invention is to provide a type inkjet composition and a container for filling the composition.

The present inventors have made intensive studies to solve the above problems. As a result, it was found that the above problems can be solved by defining the acid value and amine value of the pigment dispersant contained in the ultraviolet-curable inkjet composition and the amount of water contained in the composition within a certain range. I discovered it and completed the present invention.

That is, the present invention is as follows.
[1]
An ultraviolet curable inkjet composition containing a pigment, a pigment dispersant, a polymerizable compound, and a photopolymerization initiator and contained in a container,
The water content is 0.05% by mass or more and 1.0% by mass or less with respect to the total amount of the ultraviolet curable inkjet composition, and the acid value and amine value of the pigment dispersant are both 50 mgKOH/g or less. An ultraviolet-curable inkjet composition, at least one of which is 10 mgKOH/g or more.
[2]
[1] The UV-curable inkjet composition according to [1], wherein the total amount of the acid value and the amine value of the pigment dispersant is 15 mgKOH/g or more and 90 mgKOH/g or less.
[3]
The ultraviolet-curable inkjet composition according to [1] or [2], which contains a radically polymerizable compound as the polymerizable compound.
[4]
The ultraviolet-curable inkjet composition according to any one of [1] to [3], which contains an acylphosphine oxide compound as the photopolymerization initiator.
[5]
The ultraviolet-curable inkjet composition according to any one of [1] to [4], which contains a polymerizable compound having a vinyl ether group and a (meth)acrylate group as the polymerizable compound.
[6]
The UV-curable inkjet composition according to [5], wherein the polymerizable compound having a vinyl ether group and a (meth)acrylate group is contained in an amount of 10 to 70% by mass based on the total amount of the UV-curable composition.
[7]
As the polymerizable compound having a vinyl ether group and a (meth)acrylate group, the following general formula (1):
_CH2 =CR1 ^{- COOR2 -} O-CH=CH-R3 (1)
(In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. The ultraviolet-curable inkjet composition according to [5] or [6], which contains a vinyl ether group-containing (meth)acrylic acid ester represented by the following.
[8]
The UV-curable inkjet composition according to [7], wherein the vinyl ether group-containing (meth)acrylic acid ester is 2-(vinyloxyethoxy)ethyl acrylate.
[9]
A container containing the ultraviolet-curable inkjet composition according to any one of [1] to [8].
[10]
The container is made of a member having an oxygen permeability of 0.01 cc to 5.0 cc·20 μm/(m ² ·day·atm) at 23° C. and humidity of 65%. or at least a container filled with the ultraviolet curable inkjet composition, at an oxygen permeability of 0.01 cc to 5.0 cc·20 μm/(m ² · The container according to [9], which is at least one of sealed with a package made of a member that is (day·atm).

1 is an exploded perspective view showing an example of a container of the present invention; FIG.

Embodiments for carrying out the present invention (hereinafter referred to as "present embodiments") will be described in detail below with reference to the drawings as necessary, but the present invention is not limited to these. Various modifications are possible without departing from the gist of the invention. In the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted. In addition, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the illustrated ratios. In addition, "(meth)acryl" as used herein means "acryl" and corresponding "methacryl", and "(meth)acrylate" means "acrylate" and corresponding "methacrylate".

[Ultraviolet-curable inkjet composition]
The ultraviolet curable composition of this embodiment contains a pigment, a pigment dispersant, a polymerizable compound, a photopolymerization initiator, and water, and is accommodated in a container. The amount of water contained therein is 0.05% by mass or more and 1.0% by mass or less with respect to the total amount of the ultraviolet curable composition. The acid value and amine value of the pigment dispersant are both 50 mgKOH/g or less, and at least one of them is 10 mgKOH/g or more. The UV-curable composition is preferably a radical polymerizable UV-curable composition from the viewpoints of further enhancing its curability, and from the viewpoint of seeking high versatility and high convenience.

In the UV-curable composition, both the acid value and the amine value of the pigment dispersant are 50 mgKOH/g or less, and the water content in the UV-curable composition is 1.0% by mass or less, so that foreign matter It is possible to suppress the precipitation of It is thought that foreign matter precipitates when the water content is high or when a pigment dispersant having an acid value or an amine value is present. , presumably because the deposition of foreign matter is suppressed. Further, when at least one of the acid value and amine value of the pigment dispersant is 10 mgKOH/g or more, the curability of the UV-curable composition can be made more sufficient. It is believed that this is because the pigment dispersant having such an oxidation or amine value effectively acts as a catalyst for the curing reaction of the polymerizable compound. Furthermore, by setting the water content in the ultraviolet-curable composition to 0.05% by mass or more, the production efficiency of the ultraviolet-curable composition can be enhanced. In particular, the amount of water in the UV-curable composition is highly dependent on the amount of water present (mixed) in the synthesized polymerizable compound. Therefore, it is presumed that the load due to the step of reducing the amount of water present in the polymerizable compound can be reduced. As a result, the production time can be shortened, the process can be simplified, labor can be reduced, and the production cost can be reduced. However, the factors are not limited to these.

The ultraviolet curable composition can be used for various uses, and the uses are not limited. Applications include, for example, ink and polymerization molding. Among these, the one for ink is preferred, and the one for inkjet is also preferred from the viewpoint of more effectively and reliably exhibiting the effects of the present invention. Hereinafter, the ultraviolet curable composition of the present embodiment will be referred to as an inkjet ink composition (hereinafter also simply referred to as "composition") which is one embodiment of an inkjet composition (composition used by being ejected by an inkjet method). The use case will be described in more detail, but the ultraviolet-curable composition is not limited to this.

(Polymerizable compound)
The composition contains a polymerizable compound. The polymerizable compound can be polymerized by itself or by the action of a polymerization initiator to cure the composition on the recording medium by applying energy such as light irradiation. Although the polymerizable compound is not particularly limited, conventionally known monofunctional, difunctional, and trifunctional or higher polyfunctional monomers and oligomers can be used. A polymerizable compound may be used individually by 1 type, and may be used in combination of 2 or more type. These polymerizable compounds are exemplified below.

The polymerizable compound preferably contains a radically polymerizable compound from the viewpoint of further enhancing the curability of the composition and from the viewpoint of seeking high versatility and high convenience. In addition or instead of that, the polymerizable compound enhances curability, further lowers the viscosity of the composition, and, when a polymerization initiator is used, from the viewpoint of enhancing the solubility of the polymerization initiator, the vinyl ether group and It is preferable to contain a polymerizable compound having a (meth)acrylate group. As the polymerizable compound having a vinyl ether group and a (meth)acrylate group, a radically polymerizable compound having a vinyl ether group and a (meth)acrylate group is preferred. Examples of such polymerizable compounds include (meth)acrylates having a monofunctional or polyfunctional vinyl ether group, and from the same viewpoint as above, these are preferred.

The monofunctional (meth)acrylate having a vinyl ether group is not particularly limited, but from the viewpoint of further increasing the viscosity of the composition, increasing the flash point, and further increasing the curability of the composition, the following general formula (1) :
_CH2 =CR1 ^{- COOR2 -} O-CH=CH-R3 (1)
It is preferable to contain a vinyl ether group-containing (meth)acrylic acid ester represented by. 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 a It is a monovalent organic residue.

Vinyl ether group-containing (meth)acrylic acid esters represented by the general formula (1) include, for example, 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, (meth)acrylic acid 1-methyl-2-vinyloxyethyl, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 1-methyl-3-vinyloxypropyl (meth)acrylate, 1-(meth)acrylate Vinyloxymethylpropyl, 2-methyl-3-vinyloxypropyl (meth)acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth)acrylate, 3-vinyloxybutyl (meth)acrylate, (meth)acrylic acid 1 -methyl-2-vinyloxypropyl, 2-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethyl (meth)acrylate Cyclohexylmethyl, 3-vinyloxymethylcyclohexylmethyl (meth)acrylate, 2-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenylmethyl (meth)acrylate, m-vinyl(meth)acrylate oxymethylphenylmethyl, o-vinyloxymethylphenylmethyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, (meth)acrylate 2-(vinyloxyethoxy)propyl acrylate, 2-(vinyloxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxy)acrylate (meth) Isopropoxy)isopropyl, 2-(vinyloxyethoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)(meth)acrylate ethyl, 2-(vinyloxyisopropoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)propyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxy)acrylate (meth) Xyethoxyethoxy)isopropyl, 2-(vinyloxyethoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)acrylate (meth) isopropyl, 2-(vinyloxyethoxyethoxyethoxy)ethyl (meth)acrylate and 2-(vinyloxyethoxyethoxyethoxyethoxy)ethyl (meth)acrylate. These are used individually by 1 type or in combination of 2 or more types.

Among these, 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. Both 2-(vinyloxyethoxy)ethyl acrylate and 2-(vinyloxyethoxy)ethyl methacrylate have a simple structure and a small molecular weight, and therefore can significantly reduce the viscosity of the composition. Examples of 2-(vinyloxyethoxy)ethyl (meth)acrylate include 2-(2-vinyloxyethoxy)ethyl (meth)acrylate and 2-(1-vinyloxyethoxy)ethyl (meth)acrylate. , 2-(vinyloxyethoxy)ethyl acrylate includes 2-(2-vinyloxyethoxy)ethyl acrylate and 2-(1-vinyloxyethoxy)ethyl acrylate. 2-(Vinyloxyethoxy)ethyl acrylate is superior to 2-(vinyloxyethoxy)ethyl methacrylate in curability.

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

The composition may contain one or more of monofunctional, difunctional, and trifunctional or higher polyfunctional monomers other than those exemplified above. Examples of such monomers include, but are not limited to, unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid; salts of the unsaturated carboxylic acids; Esters, urethanes, amides and anhydrides; acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.

Monofunctional, difunctional, and trifunctional or higher polyfunctional oligomers are not particularly limited. Examples include acrylates, aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates and polyester (meth)acrylates.

Also, an N-vinyl compound may be contained as another monofunctional monomer or polyfunctional monomer. Examples of N-vinyl compounds include, but are not limited to, N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, and derivatives thereof. be done.

The composition may contain a monofunctional (meth)acrylate as a monofunctional monomer. In this case, the viscosity of the composition is low, the solubility of the photopolymerization initiator and other additives is excellent, and the ejection stability during ink jet recording is easily improved. Examples of monofunctional (meth)acrylates include, but are not limited to, isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomyristyl (meth)acrylate. ) acrylate, isostearyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate , methoxypolyethylene glycol (meth)acrylate, methoxypropyleneglycol (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxy Propyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, lactone-modified flexible (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl Oxyethyl (meth)acrylate, 2-(isopropenoxyethoxy)ethyl (meth)acrylate, 2-(isopropenoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropenoxyethoxyethoxyethoxy)ethyl (meth) Acrylates, 2-(isopropenoxyethoxyethoxyethoxyethoxy)ethyl (meth)acrylate, polyethylene glycol monovinyl ether (meth)acrylate, and polypropylene glycol monovinyl ether (meth)acrylate. Among these, phenoxyethyl (meth)acrylate is preferred.

The content of the monofunctional monomer is preferably 10-60% by mass, more preferably 20-50% by mass, based on the total amount (100% by mass) of the composition. By setting it within the above preferred range, there is a tendency that the curability, the solubility of the initiator, the storage stability, and the ejection stability are more excellent.

The composition may contain a polyfunctional (meth)acrylate as a polyfunctional monomer. Among them, the bifunctional (meth)acrylate is not particularly limited, and examples thereof include triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate. ) 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 di(meth)acrylate of bisphenol A, PO (propylene oxide) of bisphenol A Adducts di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate.

Examples of tri- or more functional (meth)acrylates include trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and 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 preferred, and dipropylene Glycol di(meth)acrylate and pentaerythritol tri(meth)acrylate are more preferred.

The content of the polyfunctional monomer is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, even more preferably 15 to 40% by mass, relative to the total amount (100% by mass) of the composition. By setting it to the above preferable range, there is a tendency that the curability, storage stability, ejection stability, and surface gloss of printed matter are excellent.

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

The content of the polymerizable compound is preferably 35 to 95% by mass, more preferably 45 to 90% by mass, relative to the total amount (100% by mass) of the composition. 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 matter can be further improved. can be done.

(pigment)
The composition contains a pigment as a coloring material. Examples of pigments include inorganic pigments and organic pigments. Examples of inorganic pigments include, but are not limited to, furnace black, lamp black, acetylene black, carbon black (CI Pigment Black 7) such as channel black, iron oxide, and titanium oxide.

Examples of organic pigments include, but are not limited to, quinacridone-based pigments, quinacridonequinone-based pigments, dioxazine-based pigments, phthalocyanine-based pigments, anthrapyrimidine-based pigments, anthanthrone-based pigments, indanthrone-based pigments, flavanthrone-based pigments, perylene-based pigments, diketopyrrolopyrrole-based pigments, perinone-based pigments, quinophthalone-based pigments, anthraquinone-based pigments, thioindigo-based pigments, benzimidazolone-based pigments, isoindolinone-based pigments, azomethine-based pigments, and azo-based pigments. .

A pigment is used individually by 1 type or in combination of 2 or more types.

The content of the pigment is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and 1.0 to 5.0% by mass with respect to the total amount (100% by mass) of the composition. More preferred. When the content of the pigment is within the above range, the color developability tends to be more excellent.

(Pigment dispersant)
The composition contains one or more pigment dispersants in order to improve pigment dispersibility. The dispersant is not particularly limited except for the acid value and amine value described below, and examples thereof include dispersants commonly used for preparing pigment dispersions, such as polymer dispersants. Specific examples include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxies. Among resins, those containing one or more kinds of resins as a main component can be mentioned. Commercially available polymeric dispersants include the Ajisper series manufactured by Ajinomoto Fine-Techno Co., Ltd., the Solsperse series available from Lubrizol (e.g., "Solsperse 36000"), the Disperbyk series manufactured by BYK Chemie, and Kusumoto Kasei. Disparon series manufactured by the company can be mentioned.

In the composition of the present embodiment, at least one of the acid value and amine value of the pigment dispersant is 10 mgKOH/g or more from the viewpoint of improving the curability of the composition and the dispersion stability of the pigment. Moreover, from the viewpoint of suppressing polymerization gelation of the composition, both the acid value and the amine value of the pigment dispersant are 50 mgKOH/g or less. A dispersant having a high acid value or amine value acts effectively as a catalyst for the polymerization reaction (curing reaction) of a polymerizable compound, particularly a radically polymerizable compound, thereby improving the curability of the composition and further reducing its polarity. It is believed that this effect improves the dispersion stability of the pigment. On the other hand, a dispersant with a high acid value or amine value acts effectively as a catalyst for the polymerization reaction (hardening reaction) of a polymerizable compound, especially a radically polymerizable compound. It is thought that there is a tendency to lower the storage stability of the product. At least one of the acid value and amine value of the pigment dispersant is preferably 15 mgKOH/g or more, 20 mgKOH/g or more, in that order, 45 mgKOH/g or less, 40 mgKOH/g or less, and 30 mgKOH/g or less, in that order. .

The total amount of the acid value and amine value of the pigment dispersant is 10 mgKOH/g or more, 15 mgKOH/g or more, 20 mgKOH/g or more, 30 mgKOH/g or more from the viewpoint of improving the curability of the composition and the dispersion stability of the pigment. , 100 mgKOH/g or less, 90 mgKOH/g or less, 85 mgKOH/g or less, 82 mgKOH/g or less, in that order, which is preferable in terms of the above.

The acid value and amine value of the pigment dispersant can be obtained by potentiometric titration. Multiple types of pigment dispersants may be added to the composition. Also in this case, the acid value and amine value of each pigment dispersant should satisfy the ranges specified in the present invention. Thus, a pigment dispersant whose measured acid value and amine value are within the above range may be selected and used for preparing the composition.

(moisture)
The composition of the present embodiment contains water, and the amount of water is 0.05% by mass or more and 1.0% by mass or less with respect to the total amount (100% by mass) of the composition. From the viewpoint of further increasing the production efficiency of the composition, and from the viewpoint of further increasing the storage stability of the composition when the composition contains a polymerizable compound having a vinyl ether group and a (meth)acrylate group, the water content is 0.5. It is preferably 05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more. This is because water has the effect of inhibiting the polymerization of a polymerizable compound having a vinyl ether group and a (meth)acrylate group. In addition, the water content is preferably 1.0% by mass or less, and more preferably 0.8% by mass or less, from the viewpoint of suppressing deterioration of the curability of the composition and suppressing the precipitation of foreign substances. Preferably, it is 0.5% by mass or less, and more preferably 0.5% by mass or less. As described above, water has the effect of inhibiting the polymerization of a polymerizable compound having a vinyl ether group and a (meth)acrylate group, and tends to lower the curability of the composition. In addition, it is considered that water causes aggregation of the pigment, and the aggregation of the pigment results in deposition of foreign matter.

Methods for adjusting the amount of water in the composition include, for example, a method of reducing the amount of water in each component of the composition, such as a polymerizable compound, a method of removing water from the composition, and a method of mixing water during preparation of the composition. A method of reducing the amount of water is included. Among these, methods for reducing the amount of water in the polymerizable compound include, more specifically, a method of distilling and purifying the polymerizable compound, a method of permeating the polymerizable compound through a semi-permeable membrane that selectively permeates water, and a method of selectively adsorbing water to a water adsorbent that adsorbs water. Among these, the method of purification by distillation is preferable from the viewpoint of reducing the water content more efficiently and reliably. The water content is measured according to the method described in the Examples below.

Examples of water include pure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, and distilled water, and water from which ionic impurities are removed as much as possible, such as ultrapure water. Further, if water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, it is possible to prevent the generation of mold and bacteria when the ink is stored for a long period of time. This tends to further improve the storage stability.

In addition to the components described above, the composition of the present embodiment may contain any component that can be used in a conventional UV-curable inkjet ink composition. Such optional components include, for example, polymerization initiators, colorants such as pigments and dyes, dispersants, polymerization inhibitors, surfactants, penetrants, humectants, dissolution aids, viscosity modifiers, and pH adjusters. agents, antioxidants, preservatives, fungicides, corrosion inhibitors, and chelating agents and other additives and solvents to trap metal ions that affect dispersion. These are each used individually by 1 type or in combination of 2 or more types.

(Polymerization initiator)
The 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 and cations by thermal energy or light energy such as ultraviolet rays and initiates the polymerization of the polymerizable compound, but it is a photopolymerization initiator. is preferred, and a radical photopolymerization initiator is preferred. Although the radical photopolymerization initiator is not particularly limited, acylphosphine oxide photopolymerization initiators and thioxanthone photopolymerization initiators are preferred, and acylphosphine oxide photopolymerization initiators are more preferred.

[Acylphosphine oxide photopolymerization initiator]
The composition preferably contains an acylphosphine oxide photopolymerization initiator. Acylphosphine oxide-based photopolymerization initiators are susceptible to oxygen inhibition, but are suitable for curing with long-wavelength LEDs. In addition, the acylphosphine oxide photopolymerization initiator can dissolve 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.

Acylphosphine oxide-based photopolymerization initiators are not particularly limited, but specific examples include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide. , and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

Commercially available acylphosphine oxide-based photopolymerization initiators are not particularly limited. Lambson's trade name, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) and DAROCUR TPO (BASF's trade name, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), SPEEDCURE TPO-L ( Lambson's trade name, ethyl-(2,4,6-trimethylbenzoyl)phenylphosphine oxide).

The content of the acylphosphine oxide-based photopolymerization initiator is preferably 3 to 20% by mass with respect to the total amount (100% by mass) of the composition. When the content is 3.0% by mass or more, the curability tends to be more excellent. From the same point of view, the content of the acylphosphine oxide photopolymerization initiator is more preferably 4% by mass or more, and even more preferably 7% by mass or more. In addition, when the content is 20% by mass or less, the dissolution of solids and storage stability are maintained well, and the reliability tends to be excellent. From the same point of view, the content of the acylphosphine oxide photopolymerization initiator is more preferably 15% by mass or less, and even more preferably 13% by mass or less.

[Thioxanthone-based photopolymerization initiator]
The composition may contain a thioxanthone photoinitiator. By containing a thioxanthone-based photopolymerization initiator in the composition, surface tackiness can be reduced, and in particular, when a thin film is susceptible to oxygen inhibition, the ink surface can be cured to prevent color mixing and bleeding between dots. Moreover, it is preferable to use both an acylphosphine oxide-based photopolymerization initiator and a thioxanthone-based photopolymerization initiator, because the curing process by UV-LED tends to be excellent, and the curability and adhesion of the composition tend to be even more excellent.

Although the thioxanthone-based photopolymerization initiator is not particularly limited, specifically, it preferably contains one or more selected from the group consisting of thioxanthone, diethylthioxanthone, isopropylthioxanthone, and chlorothioxanthone. Although not particularly limited, the preferred diethylthioxanthone is 2,4-diethylthioxanthone, the preferred isopropylthioxanthone is 2-isopropylthioxanthone, and the preferred chlorothioxanthone is 2-chlorothioxanthone. A composition containing such a thioxanthone-based photopolymerization initiator tends to be more excellent in curability, storage stability, and ejection stability. Among these, a thioxanthone-based photopolymerization initiator containing diethylthioxanthone is preferable. By including diethylthioxanthone, there is a tendency that ultraviolet light (UV light) in a wide range can be more efficiently converted into active species.

Commercially available thioxanthone-based photopolymerization initiators are not particularly limited, but specific examples include Speedcure DETX (2,4-diethylthioxanthone), Speedcure ITX (2-isopropylthioxanthone), and Speedcure CTX (2-chlorothioxanthone). , SPEEDCURE CPTX (1-chloro-4-propylthioxanthone (manufactured by Lambson), KAYACURE DETX (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.).

The content of the thioxanthone-based photopolymerization initiator is preferably 0.5 to 5.0% by mass, more preferably 1.0 to 4.0% by mass, relative to the total amount (100% by mass) of the composition. When the content is 0.5% by mass or more, the surface tackiness can be further reduced, and the ink surface is hardened when the ink is thin, which is susceptible to oxygen inhibition, and color mixture and bleeding between dots tend to be more prevented. It is in. In addition, when the content is 5.0% by mass or less, the ink tends to be less colored by the initiator itself, the hue is less yellowed, and the adhesiveness of the cured film is more excellent.

(Other photopolymerization initiators)
The composition may further contain one or more photoradical polymerization initiators or photocationic polymerization initiators other than those described above. Photoradical polymerization initiators other than the above include, for example, aromatic ketones, aromatic onium salt compounds, organic peroxides, thio compounds (thiophenyl group-containing compounds, etc.), α-aminoalkylphenone compounds, hexaarylbiimidazoles. compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

Commercially available photoradical polymerization initiators other than the above are not particularly limited, but examples include IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethan-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-one}, 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)-9H- 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) (all from BASF), Speedcure TPO (all from Lambson), Lucirin TPO, LR8893, LR8970 (all from BASF), and Uvecryl P36 (from UCB). be done.

Other photocationic polymerization initiators are not particularly limited, but specific examples include sulfonium salts and iodonium salts.

The content of the photopolymerization initiator is preferably 5 to 20% by mass with respect to the total amount (100% by mass) of the composition. When the content is within the above range, it tends to be possible to sufficiently exert the ultraviolet curing speed and to avoid the undissolved photopolymerization initiator and the coloring caused by the photopolymerization initiator.

(Polymerization inhibitor)
The composition may contain one or more polymerization inhibitors from the viewpoint of further enhancing its storage stability. Although the polymerization inhibitor is not particularly limited, for example, compounds having a 2,2,6,6-tetramethylpiperidine-N-oxyl skeleton, compounds having a 2,2,6,6-tetramethylpiperidine skeleton, 2 , 2,6,6-tetramethylpiperidine-N-alkyl skeleton compounds and hindered amine compounds such as 2,2,6,6-tetramethylpiperidine-N-acyl skeleton compounds; 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'-methylenebis(4-ethyl-6-butylphenol), and 4,4'-thiobis(3-methyl-6-t-butylphenol).

The ultraviolet curable composition of this embodiment is to be accommodated in a container. In other words, the container of this embodiment contains the ultraviolet-curable composition of this embodiment. Hereinafter, the case where the ultraviolet curable composition is used as the inkjet ink composition will be described in more detail.

(container)
One aspect of the present invention is an ink container containing a non-aqueous ink composition. As used herein, the term "container" is a concept that includes containers and packaging bodies, and refers to those that directly or indirectly contain the ink composition. That is, the container is a container filled with the ultraviolet-curable composition, or at least a container filled with the ultraviolet-curable composition and sealed with a package made of members. The ink containing body is used for storing and transporting the ink composition before the ink composition is used in the recording apparatus, and when used, the ink composition contained in the ink containing body is supplied to the recording apparatus. It is something to do.

Modes of the ink container include, but are not limited to, ink cartridges, packs, bottles, tanks, bottles, and cans. Among these, ink cartridges, packs, bottles, and tanks are preferred, and packs are more preferred, from the viewpoint of being widely used and of being easy to control the water permeability and oxygen permeability to desired values, which will be described later.

FIG. 1 shows an exploded perspective view showing an example of the ink container of the present embodiment. The ink cartridge 3 comprises an ink pack 70 filled with ink, and a cartridge case 72 comprising a main body case 76 for housing and protecting the ink pack 70 and a lid portion 78 . The ink pack 70 has an ink supply port 74 . The body case 76 has a notch portion 80 and a groove portion 86 , and the lid portion 78 has a pressing portion 82 and a hook portion 84 . In the ink cartridge 3 , the ink pack 70 is housed in the body case 76 and the lid portion 84 . At this time, the ink supply port 74 is fitted into the notch portion 80 and then the pressing portion 82 and the notch portion 80 are engaged with each other. It is fixed by being sandwiched. Further, the body case 76 and the lid portion 84 are hermetically sealed by fitting the hook portion 84 into the groove portion 86 . The ink pack 70 and the cartridge case 72 correspond to the "ink container" of this embodiment. Further, a structure for directly containing an ink composition, such as the ink pack 70, of the ink container is called a container. An ink container consisting only of a container, for example, a container in which the container itself is also a container may be used. Moreover, the container may be provided with a package (not shown). The package may contain at least the container and seal it, may contain the entire container, or may contain at least the container and be contained inside the container. . It may be a container consisting of a container and a package.

The mode of use of the ink containing body is not particularly limited, but for example, the ink containing body, which is separate from the recording apparatus, is mounted in the recording apparatus, and the ink composition is discharged from the ink containing body in the state of being mounted in the recording apparatus. A mode (A) such as a cartridge that supplies to the recording apparatus, a mode (B) such as a bottle that supplies the ink composition to an ink tank or the like of the recording apparatus from an ink container that is separate from the recording apparatus, and an ink Aspect (C) in which the container is preliminarily provided as part of the recording apparatus is exemplified. In addition, in the case of the mode (A) and the mode (C), the ink composition is supplied to the head of the recording apparatus from the mounted container or the installed ink container through a connecting part such as an ink tube. to record. Further, in the aspect (B), after the ink composition is transferred from the ink containing body to the ink tank or the like of the recording apparatus, the ink composition is supplied from the ink tank to the head of the recording apparatus through a connecting portion such as an ink tube. to record.

The material of the members constituting the container and package such as the ink pack 70 is not particularly limited, but examples include polyethylene terephthalate (PET), polypropylene, polyethylene, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer (EVOH), and the like. ), resins such as polystyrene; or inorganic materials such as glass. In addition, the above constituent materials may be used by blending them in an appropriate ratio, or may be used by stacking a plurality of kinds.

A film is preferable as the above constituent member in terms of flexibility and weight reduction. The material of the member is not particularly limited as a durable film material, but examples include plastic films such as polyethylene terephthalate (PET), polyethylene, polypropylene, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer, and polystyrene. is mentioned. Among these, high-density, low-density, or linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and polystyrene are preferred. The film material may be a laminated film or a stretched film.

The oxygen permeability of the container of the ink containing body or the member of the package that houses and seals the container is 0.01 cc to 5.0 cc·20 μm/(m ² ·day·atm) at 23° C. and 65% humidity. . An oxygen permeability of 0.01 cc·20 μm/(m ² ·day·atm) or more is preferable in terms of flexibility in designing the member, and can suppress polymerization and gelation of the composition during storage. There is a tendency. When the oxygen permeability is 5.0 cc·20 μm/(m ² ·day·atm) or less, the dissolved oxygen content of the composition during storage tends to be less likely to change, and the composition has ejection stability. tend to improve. The oxygen permeability can be measured by the method specified in JIS K 7126 (ISO 15105).

In order to improve the oxygen permeability, the ink container may have a gas barrier layer. The gas barrier layer is not particularly limited, but examples thereof include a metal layer such as an aluminum layer, an ethylene-vinyl alcohol copolymer layer, and an organic layer such as a polyvinyl alcohol layer.

The total thickness of the member is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, still more preferably 40 μm or more, and even more preferably 70 μm or more. When the total thickness is 10 μm or more, the water content and dissolved oxygen content of the contained ink composition tend to be less likely to change, and the strength of the ink containing body tends to be obtained. Also, the total thickness is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. When the total thickness is 200 μm or less, visibility and flexibility tend to be further improved.

The volume of the ink composition that the ink container can accommodate is preferably 100 to 3,000 mL, more preferably 100 to 2,000 mL, even more preferably 100 to 1,000 mL, and particularly preferably 100 mL. ~800 mL, more preferably 200-800 mL. When the capacity of the ink container is within the above range, the ink composition can be used up after the start of use of the ink container and the amount of dissolved oxygen in the ink in the ink container remains almost unchanged. There is an advantage that the amount of dissolved oxygen in the ink composition in the ink composition does not easily change.

The moisture permeability of the member is preferably 20 g/m ² ·24 hours or less, more preferably 10 g/m ² ·24 hours or less, and even more preferably 5.0 g/m ² ·24 hours or less. . When the moisture permeability is 20 g/m ² ·24 hours or less, the amount of moisture in the contained composition tends to be difficult to increase, the pigment particle size is less likely to change, and the generation of foreign matter is suppressed. It tends to improve the long-term storage stability of the composition. The water permeability of the ink container is not limited, but is preferably 0.10 g/m ² ·24 hours or more, more preferably 0.20 g/m ² from the viewpoint of design freedom. · 24 hours or more, more preferably 1.0 g/m ² ·24 hours or more, and even more preferably 2.0 g/m ² ·24 hours or more. The moisture permeability can be measured by gas chromatography.

As described above, according to the present embodiment, it is possible to provide a container that contains an ultraviolet-curable composition that has excellent curability, can suppress deposition of foreign substances, and has high production efficiency.

The inkjet device of the present embodiment uses the above-described inkjet composition and container, and is equipped with an inkjet head that ejects the composition by an inkjet method. It has a discharge step of discharging a substance. A curing process for discharging the composition onto the discharge target body and curing the composition adhering to the discharge target body by irradiating ultraviolet rays, and an irradiation device for performing the curing process may be provided. 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 an ultraviolet light source, and an ultraviolet light emitting diode is more preferable in terms of miniaturization and power saving. As the ultraviolet light emitting diode, one having an emission peak wavelength preferably in the range of 360 to 420 nm is preferable because it is easily available. The irradiation energy in the curing step is preferably 100 to 1000 mJ/cm ² , 800 mJ/cm ² or less, mJ/cm ² or 600 mJ/cm ² or less, in terms of sufficiently curing the composition and shortening the curing time. 200 mJ/cm ² or more and 300 mJ/cm ² or more are preferable in that order. Configurations of the method and apparatus other than those described above are not particularly limited. For example, a conventionally known configuration may be provided as another configuration. According to the inkjet device and the inkjet method of the present embodiment, the inkjet composition not only has excellent curability, but also can suppress the deposition of foreign matters in the composition, so that the ejection stability is also excellent. In addition, particularly when the composition contains a polymerizable compound having a vinyl ether group and a (meth)acrylate group, the composition has excellent storage stability even though the composition is cured by irradiation with ultraviolet rays. become a thing. Furthermore, when the composition contains a polymerizable compound having a vinyl ether group, the viscosity of the composition can be lowered, so the ejection stability can be further improved from this point of view.

Hereinafter, the present invention will be described more specifically using examples and comparative examples. The present invention is by no means limited by the following examples.

[Material for UV-curable composition]
The main materials for the UV-curable composition used in the following examples and comparative examples are as follows.
[Color material]
P. I. pigment blue 15:4
[Pigment Dispersant]
BYK9076, BYKJET9150, BYK2155, BYK2008, DISPERBYK102, ANTI-TERRA U100 (product name manufactured by BYK-Chemie Japan)
Ajisper PB881, Ajisper PN411 (trade names manufactured by Ajinomoto Fine-Techno Co., Ltd.)
[Polymerizable compound]
VEEA (2-(2-vinyloxyethoxy)ethyl acrylate, manufactured by Nippon Shokubai Co., Ltd., number of functional groups 1)
PEA (phenoxyethyl acrylate, manufactured by Osaka Organic Chemical Co., Ltd., number of functional groups: 1)
DPGDA (dipropylene glycol diacrylate, manufactured by Sartomer, number of functional groups: 2)
SR444 (pentaerythritol triacrylate, manufactured by Nippon Kayaku Co., Ltd., number of functional groups 3)
[Polymerization inhibitor]
MEHQ (hydroquinone monomethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd.)
[Polymerization initiator]
IRGACURE TPO (trade name manufactured by BASF, solid content 100% by mass)
IRGACURE 369 (trade name manufactured by BASF, solid content 100% by mass)
KAYACURE DETX (trade name manufactured by Nippon Kayaku Co., Ltd., solid content 100% by mass)

(Examples 1 to 25, Comparative Examples 1 to 11)
[Preparation of UV-curable composition]
Each material was prepared as a composition with the composition (% by mass) shown in Tables 1 and 2 below. First, PEA, a pigment, and a pigment dispersant among the materials are mixed and sufficiently stirred to disperse the pigment. things). In addition, each polymerizable compound was used after purifying each polymerizable compound used in each example and comparative example once or multiple times, or by adding ion-exchanged water to the composition. The amounts were adjusted to the values shown in the table. Next, a laminated film made by laminating an aluminum deposition film on a high-density polyethylene film (thickness 100 μm) is stacked with the aluminum deposition film (thickness 10 μm) facing outward, and the periphery is thermally welded to create a container pack. Each of the compositions prepared above was filled in a container with a capacity of 700 mL, the container was sealed so as to prevent air from entering, and the container was housed in a protective case to obtain a composition container. However, Examples 20 to 25 differed from the other examples in the thickness of the aluminum deposition film of the film.

(Measurement of moisture content)
Using a moisture meter (manufactured by Hiranuma Sangyo Co., Ltd., product name "automatic heating and vaporization moisture measurement system AQS-22010"), the moisture content in the UV-curable composition was measured by the Karl Fischer coulometric method. The results are shown in Tables 1 and 2 (by mass).

(Measurement of acid value and amine value)
The acid value and amine value of the pigment dispersant were measured according to JIS K 0070 and JIS K 7237, respectively. Measurement was performed using AT610 manufactured by Kyoto Electronics Manufacturing Co., Ltd.

(oxygen permeability)
The oxygen permeability of the film constituting the container used for the composition container prepared for each example was measured. The oxygen permeability was measured at 23° C. and 65% humidity according to JIS K 7126 Plastic-Film and Sheet Gas Permeability Test Method (Gas Chromatograph Method). One side (low pressure side) separated by the test piece was kept in a vacuum, and a test gas was introduced into the other (high pressure side). It was measured by the tograph method and the gas permeability was calculated.

(Curability evaluation)
Using a bar coater, the UV-curable composition was applied onto a PET film (PET50A PLshin [trade name], manufactured by Lintec) to prepare a coating film having a thickness of 14 μm. After that, ultraviolet rays having an irradiation intensity of 1100 mW/cm ² and a wavelength of 395 nm were irradiated to cure the coating film. The cured coating film (cured film) was rubbed 10 times with a cotton swab with a weight of 100 g, and the curing energy (irradiation energy) at the time when no scratches were left was determined.
The irradiation energy [mJ/cm ² ] was obtained by measuring the irradiation intensity [mW/cm ² ] on the irradiated surface irradiated from the light source and multiplying it by the irradiation duration time [s]. The irradiation intensity was measured using an ultraviolet intensity meter UM-10 and a light receiving unit UM-400 (both manufactured by KONICA MINOLTA SENSING, INC.). Evaluation was made according to the following evaluation criteria based on the irradiation intensity results. The results are shown in Tables 1-2.
◎: 250 mJ/cm ² or less ○: Over 250 mJ/cm ² and 350 mJ/cm ² or less △: Over 350 mJ/cm ² and 400 mJ/cm ² or less ×: Over 400 mJ/cm ²

(Evaluation of pigment dispersion stability (suppression of foreign matter deposition))
After discharging for 60 minutes, the filter of the head was taken out, and the residue accumulated on the filter was visually observed and evaluated according to the following evaluation criteria. A filter with a nominal mesh size of 2800 was used. The results are shown in Tables 1-2. At least the pigment was contained in the residue that was confirmed to be generated. This evaluation is at least related to the generation of foreign matter caused by the pigment.
A: No residue.
◯: A very small amount of fine residue is present.
Δ: In addition to fine residues, there is also a small amount of large residues.
x: A considerable amount of large residue is present.
XX: The filter is almost filled with residue.

(Evaluation of polymerization gelation (thickening))
After accommodating the ultraviolet curable composition in a glass bottle, the glass bottle was sealed and stored at 60° C. for 2 weeks. The viscosity at 20 ° C. of the UV-curable composition before and after storage was measured with a viscometer manufactured by Phisica, and the viscosity of the UV-curable composition after storage was compared with the viscosity of the UV-curable composition before storage. It was calculated by what percentage the viscosity increased, that is, by what percentage the viscosity increased. This is an evaluation relating to storage stability when the composition is stored for a long period of time. Based on the results, evaluation was made according to the following evaluation criteria. The results are shown in Tables 1-3.
◎: Less than 3% thickening ○: 3% to less than 6% thickening △: 6% to less than 9% thickening ×: 9% to less than 12% thickening × ×: 12% or more thickening

(Evaluation of ejection stability)
A head having 360 nozzles was fixed at the top, and a PET film (product number "PET50 K2411 PAT1E", manufactured by Lintec Corporation) was conveyed under the nozzles of the head at 15 m/min, and the PET film was fed from 180 nozzles at 10 kHz. , the ultraviolet curable composition was ejected and continuous printing was performed. Simultaneously with printing, an image was formed by irradiating the ink composition adhered to the PET film with an LED having an emission wavelength peak of 395 nm. Every 5 minutes from the start of ejection, it was visually confirmed whether or not the ultraviolet curable composition was being ejected from all the nozzles, and evaluated according to the following evaluation criteria. The results are shown in Tables 1-3.
A: No nozzle missing for 60 minutes or more.
◯: Nozzle missing for 30 minutes or more and less than 60 minutes.
Δ: Nozzle missing for 15 minutes or more and less than 30 minutes.
x: Nozzle missing in less than 15 minutes.

(Evaluation of dehydration process efficiency (manufacturing efficiency))
Each polymerizable compound obtained by a conventional method was purified by one-time distillation using a rotary evaporator. Using VEEA after distillation and purification, UV-curable compositions having the compositions shown in Tables 1 and 2 were prepared, and their water contents were measured. The distillation purification, the preparation of the UV-curable composition, and the measurement of the water content were repeated until the water content reached the values shown in Tables 1 and 2. Evaluation was made as follows based on the number of times of distillation purification. A smaller number of distillation purifications indicates a higher dehydration process efficiency (manufacturing efficiency). The results are shown in Tables 1-3.
○: Twice or less.
△: 3 to 4 times.
×: 5 times or more.

From the results of Examples, the water content is 0.05% by mass or more and 1.0% by mass or less with respect to the total amount of the ultraviolet curable inkjet composition, and the acid value and amine value of the pigment dispersant are both When it is 50 mgKOH/g or less and at least one is 10 mgKOH/g or more, curability and pigment dispersion stability (suppression of foreign matter precipitation) are excellent, polymerization gelation is suppressed, ejection stability is excellent, and dehydration process efficiency is also improved. I know you can.

From a comparison between Examples 1, 5, and 12 and Comparative Example 8, when the water content is 1.0% by mass or less, the pigment dispersion stability (suppression of foreign substances) is excellent, and as a result, the ejection stability is improved. It can be seen that it is excellent and also excellent in curability. From a comparison between Example 1 and Comparative Example 1, when the water content is 0.05% by mass or more, polymerization gelation (thickening) can be suppressed. It is also efficient.

From a comparison between Examples 1, 2, 7 to 9, 15 to 17 and Comparative Example 5, when the water content is 0.05% by mass or more and 1.0% by mass or less, the acid value and amine value of the pigment dispersant is 10 mgKOH/g or more, the pigment dispersion stability (inhibition of foreign matter deposition) is excellent, resulting in excellent ejection stability and curability.

Further, by comparing Examples 1, 2, 7 to 9, 15 to 17 and Comparative Examples 6 and 7, when the water content is 0.05% by mass or more and 1.0% by mass or less, the acid of the pigment dispersant It has been found that when both the value and the amine value are 50 mgKOH/g or less, polymerization gelation (thickening) can be suppressed, and as a result, the ejection stability tends to be excellent.

Moreover, from Comparative Examples 1 to 4, it was found that when the water content was less than 0.05% by mass, the viscosity of the composition was greatly increased. It is presumed that when the water content is small, the polymerization gelation of the composition cannot be suppressed, resulting in a large increase in viscosity. In addition, compositions with poor polymerization gelation (thickening) such as those of Comparative Examples 1 to 4 tended to have poor ejection stability, and fine gelled substances due to polymerization gelation occurred in the composition. It is presumed that the ejection stability was inferior.

Furthermore, from Comparative Examples 8 to 11, when the water content exceeded 1.0% by mass, generation of residue was observed, and the pigment dispersion stability (suppression of foreign matter deposition) decreased. It is speculated that the pigment tends to become foreign matter due to moisture. Moreover, it turned out that curability also falls in this case. In particular, in Comparative Example 9, since either the acid value or the amine value of the pigment dispersant was not 10 mgKOH/g or more, the pigment was insufficiently dispersed and residues were generated. , it is assumed that the suppression of foreign matter deposition was inferior and the generation of residues was observed also when the water content exceeded 1.0% by mass.

40... Ink cartridge 70... Ink pack 72... Cartridge case 74... Ink supply port 76... Body case 78... Lid part 80... Notch part 82... Pressing part 84... Hook part 86... Groove part .

Claims (12)

An inkjet method comprising:
An ejection step of ejecting an ultraviolet curable inkjet composition from an inkjet head onto a target object;
a curing step of curing the ultraviolet curable inkjet composition attached to the object to be discharged by irradiating with ultraviolet rays;
The inkjet head is supplied with an ultraviolet curable inkjet composition from a container containing the ultraviolet curable inkjet composition,
The ultraviolet curable inkjet composition accommodated in the container is
It contains a pigment, a pigment dispersant, a polymerizable compound, and a photopolymerization initiator, and has a water content of 0.05% by mass or more and 0.2% by mass or less with respect to the total amount of the ultraviolet-curable inkjet composition,
Both the acid value and the amine value of the pigment dispersant are 50 mgKOH/g or less, and at least one of them is 10 mgKOH/g or more,
The total amount of the acid value and amine value of the pigment dispersant is 20 mgKOH/g or more and 34 mgKOH/g or less,
35% by mass or more of a monofunctional (meth)acrylate as a monofunctional monomer relative to the total amount of the ultraviolet-curable inkjet composition;
4% by mass or more of an acylphosphine oxide-based photopolymerization initiator based on the total amount of the ultraviolet-curable inkjet composition,
The polymerizable compound includes a polymerizable compound having a vinyl ether group and a (meth)acrylate group,
The ultraviolet irradiation is performed by an ultraviolet light emitting diode with an irradiation energy of 300 to 1000 mJ/cm ² ,
The container is made of a member having an oxygen permeability of 0.01 cc to 5.0 cc·20 μm/(m ² ·day·atm) at 23° C. and humidity of 65%. or a container filled with the ultraviolet curable inkjet composition, at an oxygen permeability of 0.01 cc to 5.0 cc·20 μm/(m ² · day · atm) is sealed by a package made of a member, or at least one of
The inkjet method, wherein the container has a capacity of 700 to 3,000 mL. The inkjet method according to claim 1, wherein the capacity of the container is 700-2,000 mL. The inkjet method according to claim 1 or 2, wherein the ultraviolet curable inkjet composition contains a radically polymerizable compound as the polymerizable compound. 4. Any one of claims 1 to 3, wherein the ultraviolet-curable inkjet composition contains an acylphosphine oxide-based compound as the photopolymerization initiator in an amount of 4 to 15% by mass relative to the total amount of the ultraviolet-curable inkjet composition. 10. The inkjet method according to the paragraph. The inkjet method according to any one of claims 1 to 4, wherein the ultraviolet-curable inkjet composition is a radically polymerizable ultraviolet-curable composition. A container made of a member having an oxygen permeability of 2.0 cc to 5.0 cc·20 μm/(m ² ·day·atm) at 23° C. and 65% humidity, and filled with the UV-curable inkjet composition. Alternatively, the container filled with the UV-curable inkjet composition has an oxygen permeability of 2.0 cc to 5.0 cc·20 μm/(m ² ·day · atm) at 23 ° C. and 65% humidity. 6. The ink jet method according to any one of claims 1 to 5, wherein the ink jet method is sealed with a packaging body made of a member which is: Claims 1 to 1, wherein the ultraviolet-curable inkjet composition contains an acylphosphine oxide compound as the photopolymerization initiator in an amount of 4 to 13% by mass with respect to the total amount (100% by mass) of the ultraviolet-curable inkjet composition. 7. The inkjet method according to any one of 6. The inkjet method according to any one of claims 1 to 7, wherein the ultraviolet-curable inkjet composition contains an acylphosphine oxide-based compound and a thioxanthone-based photopolymerization initiator as the photopolymerization initiator. . The inkjet method according to any one of claims 1 to 8, wherein the member is a film obtained by laminating a gas barrier layer on a plastic film. The inkjet method according to any one of claims 1 to 9, wherein the ultraviolet curable inkjet composition contains a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate. The inkjet method according to any one of claims 1 to 10, wherein the ultraviolet-curable inkjet composition contains phenoxyethyl (meth)acrylate. an inkjet head for ejecting an ultraviolet curable inkjet composition onto an ejection target;
a light-emitting diode, which is an irradiation device that irradiates and cures the ultraviolet-curable inkjet composition adhered to the object to be discharged,
An inkjet device for performing the inkjet method according to any one of claims 1 to 11.

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