JP7698449B2 - Non-aqueous ink composition, recording method using same, and method for producing recorded matter - Google Patents

Description

The present invention relates to a non-aqueous ink composition, a recording method using the same, and a method for producing a recorded matter.

Ink compositions that are widely used include aqueous ink compositions in which coloring materials are dissolved or dispersed in water or a mixture of water and an organic solvent, and non-aqueous ink compositions in which coloring materials are dissolved or dispersed in an organic solvent that does not contain water.

For example, Patent Document 1 describes a technology related to a non-aqueous ink composition that contains a cyclic ester (lactone-based solvent) and an organic solvent having a specified flash point. Patent Document 1 describes that by containing a cyclic ester (lactone-based solvent) as a solvent, this non-aqueous ink composition dissolves part of the recording surface, allowing the ink composition to penetrate into the interior of the recording medium, thereby improving the abrasion resistance of the image.

Patent No. 6256039

Now, lactone-based solvents are solvents that easily penetrate resin substrates, and non-aqueous ink compositions that contain lactone-based solvents have high penetration into resin substrates.

However, the inventors have found that if the non-aqueous ink composition penetrates into the resin substrate to a large extent, the gloss and blocking resistance of the recorded surface of the resulting recorded material will decrease. Furthermore, if a specific low-volatility solvent is contained, the evaporation of the organic solvent within the recording device can be suppressed, but the surface drying property of the recorded material will decrease. This makes it difficult to increase the production speed of the recorded material.

The present invention aims to provide a non-aqueous ink composition that provides a printed matter with excellent surface drying properties, excellent blocking resistance, and excellent gloss.

As a result of intensive research into solving the above problems, the inventors discovered that a non-aqueous ink composition containing a specific organic solvent could solve the above problems, leading to the completion of the present invention. Specifically, the present invention provides the following:

(1) A non-aqueous ink composition containing an organic solvent and ejected by an inkjet method, the organic solvent containing an alkylamide solvent (a) and an organic solvent (b) having an enthalpy of vaporization (EOV) of 45 kJ/mol or more.

(2) The non-aqueous ink composition according to (1), wherein the organic solvent (b) contains at least one selected from the group consisting of glycol ether dialkyls, glycol ether monoalkyls, acetates, cyclic esters, carbonates, dibasic acid esters, lactates, amides, and alcohols.

(3) The non-aqueous ink composition according to (1) or (2), in which the content of the organic solvent (b) is in the range of 1% by mass or more and 30% by mass or less of the total amount of the non-aqueous ink composition.

（式（１）中、Ｒ_１は、水素若しくは炭素数１以上４以下のアルキル基であり、Ｒ_２Ｒ_３は、それぞれ独立して、水素若しくは炭素数１以上４以下のアルキル基を表す。） (4) The non-aqueous ink composition according to any one of (1) to (3), wherein the alkylamide solvent (a) is represented by the following general formula (1):

(In formula (1), R ₁ is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R ₂ and R ₃ each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms.)

(5) The non-aqueous ink composition according to (4), wherein the alkylamide solvent (a) contains at least one selected from the group consisting of N,N-diethylformamide, N,N-diethylpropanamide, and N,N-diethylacetamide.

(6) The non-aqueous ink composition according to any one of (1) to (5), wherein the content of the alkylamide solvent (a) is in the range of 1% by mass or more and 90% by mass or less of the total amount of the non-aqueous ink composition.

(7) A non-aqueous ink composition according to any one of (1) to (6), further comprising a resin, the resin having an intrinsic viscosity of 90 mL/g or more at 25°C being in the range of 5% by mass or less of the total amount of the resin.

(8) A non-aqueous ink composition according to any one of (1) to (7) above, which is ejected by an inkjet method using an inkjet recording device equipped with a heating mechanism and a fixing mechanism for fixing a substrate.

(9) A non-aqueous ink composition according to any one of (1) to (8), which is ejected by an inkjet method through a plastic tube using an inkjet recording device equipped with the plastic tube.

(10) A recording method in which the non-aqueous ink composition described in any one of (1) to (9) is ejected onto the surface of a substrate by an inkjet method.

(11) A method for producing a recorded material, comprising ejecting the non-aqueous ink composition according to any one of (1) to (9) onto the surface of a substrate by an inkjet method.

(12) A recorded matter in which a recording layer of the non-aqueous ink composition described in any one of (1) to (9) is formed on the surface of a substrate.

Even though the non-aqueous ink composition of the present invention contains a low-volatility solvent, it is possible to obtain recorded materials that have excellent surface drying properties and blocking resistance, and that exhibit excellent gloss.

Specific embodiments of the present invention are described in detail below, but the present invention is not limited to the following embodiments and can be modified as appropriate within the scope of the object of the present invention. In addition, in this specification, the notation "~" means "more than or equal to" or "less than or equal to," and the notation "X:Y~A:B" includes "X:Y" and "A:B" themselves and means the range between "X:Y" and "A:B."

1. Non-aqueous ink composition
The non-aqueous ink composition according to the present embodiment is a non-aqueous ink composition that contains an organic solvent and is ejected by an inkjet method, and is characterized in that the organic solvent contains an alkylamide solvent (a) and an organic solvent (b) having an enthalpy of evaporation (EOV) of 45 kJ/mol or more.

Such a non-aqueous ink composition can produce printed matter that has excellent surface drying properties and blocking resistance, as well as excellent gloss.

Here, "non-aqueous ink composition" means an ink composition that does not contain water (oil-based ink composition), and is different from an aqueous ink composition in which a coloring material is dissolved or dispersed in water or a mixture of water and an organic solvent. In this specification, the term "water-free" does not take into account water that is inevitably contained, such as moisture in the air or water that originates from additives, etc.

The non-aqueous ink composition according to the present embodiment may be a colored ink containing a coloring material (including colored coloring materials and black-and-white coloring materials), an ink containing a glittering pigment (scaly metal particles) for making the recorded matter (substrate) metallic, or a clear ink containing no coloring material. In the case of a clear ink containing no coloring material, an ink for forming a layer having a desired function may be mentioned. Examples of such inks include an overcoat ink composition for forming an overcoat layer that protects the recorded matter (substrate), a matte ink composition for eliminating the gloss of the recorded matter (substrate), and an ink containing an ultraviolet absorber, a light stabilizer, etc. for forming a weather-resistant layer.

Below, we will explain each component contained in the non-aqueous ink composition according to this embodiment.

[Organic solvent]
The organic solvent contains an alkylamide solvent (a) and an organic solvent (b) having an enthalpy of vaporization (EOV) of 45 kJ/mol or more.

(Alkylamide Solvent (a))
An alkylamide solvent is a compound having an alkyl group (C _n H _2n+1 --) and a --C(=O)--N-- group (amide bond), and is an organic solvent composed of a compound composed of hydrogen or an alkyl group and a --C(=O)--N-- group.

The alkylamide solvent (a) is a solvent that penetrates into the substrate to a certain extent, similar to the lactone solvent. The alkylamide solvent (a) is more volatile than the lactone solvent, and as a result, the amount of penetration into the substrate can be reduced compared to a non-aqueous ink composition containing a lactone solvent. Therefore, it is possible to improve the gloss of the recording surface of the obtained recording material while enjoying the benefits of a non-aqueous ink composition containing a lactone solvent.

In addition, since the alkylamide-based solvent (a) dries easily, a non-aqueous ink composition containing the alkylamide-based solvent (a) can obtain a recorded material with excellent surface drying properties even if it contains the organic solvent (b) described below. Furthermore, the non-aqueous ink composition that has landed on the substrate (recording medium) dries quickly, and the print is clear with less bleeding. Furthermore, if the non-aqueous ink composition contains the alkylamide-based solvent (a), which dries easily compared to the lactone-based solvent, the penetration into the substrate is somewhat lower as described above, and the amount of solvent remaining in the substrate after the surface dries is reduced. This makes it possible to suppress the occurrence of blocking, and the compatibility of the components with the inkjet recording device is also good.

The alkylamide solvent is preferably an organic solvent that does not contain an alkoxy group and is composed only of hydrogen or an alkyl group and a -C(=O)-N- group, and for example, one having the following structure can be preferably used.

（式（１）中、Ｒ_１は、水素若しくは炭素数１以上４以下のアルキル基であり、Ｒ_２Ｒ_３は、それぞれ独立して、水素若しくは炭素数１以上４以下のアルキル基を表す。）

(In formula (1), R ₁ is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R ₂ and R ₃ each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms.)

In addition, _R2 and _R3 in the formula (1) are preferably alkyl groups having 1 to 4 carbon atoms, and more preferably alkyl groups having 2 to 4 carbon atoms.

Specific examples of alkylamide solvents include N,N-diethylformamide, N,N-diethylacetamide, N,N-dipropylformamide, N,N-dibutylformamide, N,N-diethylpropanamide, N,N-dipropylpropanamide, N-ethylformamide, and N-ethylacetamide. Among these, from the viewpoint of particularly achieving the effects of the present invention, it is preferable to contain at least one selected from the group consisting of N,N-diethylformamide, N,N-diethylpropanamide, and N,N-diethylacetamide, and among these, it is particularly preferable to contain N,N-diethylformamide.

The content of the alkylamide solvent (a) is not particularly limited, but the lower limit of the content of the alkylamide solvent (a) is preferably 1% by mass or more of the total amount of the non-aqueous ink composition, more preferably 3% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 15% by mass or more. This makes it possible to obtain a recorded material with excellent surface drying properties, which further reduces bleeding of the print and makes the print clearer.

The upper limit of the content of the alkylamide solvent (a) is preferably 90% by mass or less of the total amount of the non-aqueous ink composition, more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less. This makes it possible to obtain a non-aqueous ink composition that can obtain recorded materials that exhibit superior gloss.

(Organic Solvent (b))
The organic solvent (b) is an organic solvent having an enthalpy of vaporization (EOV) of 45 kJ/mol or more. In this specification, the enthalpy of vaporization is a calculated value determined using Advanced Chemistry Development (ACD/Labs) software, version 11.02.

The higher the enthalpy of vaporization, the less volatile the organic solvent is. Organic solvents (b) with an enthalpy of vaporization (EOV) of 45 kJ/mol or more are low-volatility solvents.

By containing such an organic solvent (b) having an evaporation enthalpy (EOV) of 45 kJ/mol or more, the penetration of the alkylamide solvent (a) contained in the non-aqueous ink composition into the substrate is reduced, and a recording material exhibiting excellent glossiness can be obtained. Furthermore, since the non-aqueous ink composition can be prevented from volatilizing before it lands on the substrate (recording medium), the non-aqueous ink composition has excellent maintainability and improves the inkjet ejection properties. The evaporation enthalpy (EOV) of this organic solvent (b) is preferably 45.5 kJ/mol or more, and more preferably 46.0 kJ/mol or more. The upper limit of the evaporation enthalpy (EOV) of this organic solvent (b) is not particularly limited, but is preferably 90 kJ/mol or less, more preferably 80 kJ/mol or less, and even more preferably 70 kJ/mol or less.

The type of the organic solvent (b) having an evaporation enthalpy (EOV) of 45 kJ/mol or more is not particularly limited, but is preferably an organic solvent having an evaporation enthalpy (EOV) of 45 kJ/mol or more, such as glycol ether dialkyls, glycol ether monoalkyls, acetates, cyclic esters, carbonates, dibasic acid esters, lactates, amides, and alcohols, more preferably an organic solvent having an evaporation enthalpy (EOV) of 45 kJ/mol or more, such as glycol ether dialkyls, glycol ether monoalkyls, and carbonates, and even more preferably an organic solvent having an evaporation enthalpy (EOV) of 45 kJ/mol or more. This makes it possible to achieve a good balance between the surface dryness and glossiness of the recorded matter.

Examples of glycol ether dialkyls include diethylene glycol dibutyl ether (47.2 kJ/mol), tetraethylene glycol dimethyl ether (49.3 kJ/mol), and tetraethylene glycol diethyl ether (51.9 kJ/mol).

Examples of glycol ether monoalkyl include diethylene glycol monomethyl ether (50.1 kJ/mol), diethylene glycol monoethyl ether (51.0 kJ/mol), diethylene glycol mono-n-butyl ether (54.3 kJ/mol), triethylene glycol monomethyl ether (54.7 kJ/mol), triethylene glycol mono-n-butyl ether (60.0 kJ/mol), tetraethylene glycol monobutyl ether (66.9 kJ/mol), pentaethylene glycol monobutyl ether (72.4 kJ/mol), hexaethylene glycol monobutyl ether (77.6 kJ/mol), dipropylene glycol monomethyl ether (51.1 kJ/mol), dipropylene glycol monopropyl ether (55.8 kJ/mol), and tripropylene glycol monomethyl ether (59.1 kJ/mol).

Examples of acetates include diethylene glycol mono-n-butyl ether acetate (48.2 kJ/mol) and diethylene glycol mono-n-ethyl ether acetate (45.8 kJ/mol).

Examples of cyclic esters include ε-caprolactone (46.2 kJ/mol), δ-valerolactone (45.4 kJ/mol), and δ-hexanolactone (45.2 kJ/mol).

Examples of carbonate esters include propylene carbonate (47.8 kJ/mol) and ethylene carbonate (49.0 kJ/mol).

Examples of dibasic acid esters include dipropyl malonate (46.6 kJ/mol), diethyl succinate (45.5 kJ/mol), diethyl glutarate (47.3 kJ/mol), dimethyl adipate (46.5 kJ/mol), etc.

Examples of lactate esters include ethyl lactate (45.6 kJ/mol), butyl lactate (49.5 kJ/mol), propyl lactate (47.8 kJ/mol), ethylhexyl lactate (55.8 kJ/mol), amyl lactate (51.3 kJ/mol), and isoamyl lactate (51.0 kJ/mol).

Examples of amides include 3-methyl-2-oxazolidinone (50.4 kJ/mol), 3-ethyl-2-oxazolidinone (50.7 kJ/mol), N-methylcaprolactam (48.5 kJ/mol), N-acetylcaprolactam (47.9 kJ/mol), ε-caprolactam (51.1 kJ/mol), N-vinylcaprolactam (49.2 kJ/mol), and N,N-dimethyl-β-butoxypropionamide (48.5 kJ/mol).

Examples of alcohols include 3-methoxybutanol (46.5 kJ/mol), 3-methoxy-3-methylbutanol (46.7 kJ/mol), and diacetone alcohol (47.1 kJ/mol).

Examples of organic solvents (b) other than glycol ether dialkyls, glycol ether monoalkyls, acetates, cyclic esters, carbonates, dibasic acid esters, lactates, amides, and alcohols include hydroxy acid esters. Examples of hydroxy acid esters include triethyl citrate (61.9 kJ/mol).

The content of the organic solvent (b) having an evaporation enthalpy (EOV) of 45 kJ/mol or more is not particularly limited, but the lower limit of the content of the organic solvent (b) is preferably 1% by mass or more of the total amount of the non-aqueous ink composition, more preferably 3% by mass or more, and even more preferably 5% by mass or more. This reduces the permeability of the alkylamide solvent (a) contained in the non-aqueous ink composition into the substrate, and makes it possible to obtain a recorded product exhibiting superior glossiness. The upper limit of the content of the organic solvent (b) is preferably 30% by mass or less of the total amount of the non-aqueous ink composition, more preferably 20% by mass or less, and even more preferably 15% by mass or less. This makes it possible to obtain a recorded product with superior surface drying properties.

(Other organic solvents)
The organic solvent may contain an organic solvent other than the alkylamide solvent (a) and the organic solvent (b) having an enthalpy of evaporation (EOV) of 45 kJ/mol or more. Specifically, an organic solvent having an enthalpy of evaporation (EOV) of less than 45 kJ/mol, which is different from the alkylamide solvent, may be used.

For example, glycol ether dialkyls, glycol ether monoalkyls, acetates, cyclic esters, amides other than the above alkylamide solvent (a), lactate esters, dibasic acid esters, etc., each of which has an enthalpy of vaporization (EOV) of less than 45 kJ/mol are included.

Glycol ether dialkyls with an enthalpy of vaporization (EOV) of less than 45 kJ/mol include diethylene glycol dimethyl ether (38.0 kJ/mol), diethylene glycol methyl ethyl ether (38.8 kJ/mol), diethylene glycol diethyl ether (40.9 kJ/mol), diethylene glycol isopropyl methyl ether (40.4 kJ/mol), triethylene glycol dimethyl ether (43.4 kJ/mol), and dipropylene glycol dimethyl ether (39.8 kJ/mol).

Monoalkyl ethers with an enthalpy of vaporization (EOV) of less than 45 kJ/mol include ethylene glycol monomethyl ether (37.5 kJ/mol), ethylene glycol monoethyl ether (39.2 kJ/mol), ethylene glycol monopropyl ether (44.89 kJ/mol), propylene glycol monomethyl ether (41.6 kJ/mol), and propylene glycol monoethyl ether (43.0 kJ/mol).

Acetates with an enthalpy of vaporization (EOV) of less than 45 kJ/mol include ethylene glycol monobutyl ether acetate (42.8 kJ/mol), propylene glycol monomethyl ether acetate (39.2 kJ/mol), 2-methylbutyl acetate (37.3 kJ/mol), 3-methoxybutyl ether acetate (41.2 kJ/mol), and cyclohexyl acetate (40.9 kJ/mol).

Cyclic esters with an enthalpy of vaporization (EOV) of less than 45 kJ/mol include gamma-butyrolactone (44.0 kJ/mol) and gamma-valerolactone (44.3 kJ/mol).

Amides with an enthalpy of vaporization (EOV) of less than 45 kJ/mol include N,N-dimethyl-β-methoxypropionamide (42.5 kJ/mol) and N-vinylmethyloxazolidinone (38.3 kJ/mol).

An example of a lactate ester with an enthalpy of vaporization (EOV) of less than 45 kJ/mol is methyl lactate (44.5 kJ/mol).

Dibasic acid esters with an enthalpy of vaporization (EOV) of less than 45 kJ/mol include dimethyl malonate (41.3 kJ/mol), diethyl malonate (43.6 kJ/mol), dipropyl malonate (46.6 kJ/mol), and dimethyl succinate (43.2 kJ/mol).

In addition, organic solvents other than the above organic solvents may be contained. Specifically, alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol; ketones such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, methyl hexyl ketone, methyl isoamyl ketone, diethyl ketone, ethyl n-propyl ketone, ethyl isopropyl ketone, ethyl n-butyl ketone, ethyl isobutyl ketone, di-n-propyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, isophorone, and acetyl ketone; acetates such as methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, hexyl acetate, and octyl acetate; Examples of common organic solvents that may be used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol; saturated hydrocarbons such as n-hexane, isohexane, n-nonane, isononane, dodecane, and isododecane; unsaturated hydrocarbons such as 1-hexene, 1-heptene, and 1-octene; cyclic saturated hydrocarbons such as cyclohexane, cycloheptane, cyclooctane, cyclodecane, and decalin; cyclic unsaturated hydrocarbons such as cyclohexene, cycloheptene, cyclooctene, 1,1,3,5,7-cyclooctatetraene, and cyclododecene; aromatic hydrocarbons such as benzene, toluene, and xylene; morpholines such as N-methylmorpholine, N-ethylmorpholine, and N-formylmorpholine; terpene solvents; and ether solvents, regardless of the enthalpy of evaporation (EOV). It is preferable to select a solvent with an appropriate HLB value depending on the resin and dispersant to be combined.

The non-aqueous ink composition according to this embodiment may contain a lactone solvent having an evaporation enthalpy (EOV) of less than 45 kJ/mol, but if the lactone solvent is contained in a large amount, the effect of the present invention of obtaining a recorded material exhibiting excellent glossiness may not be obtained. The content of the lactone solvent having an evaporation enthalpy (EOV) of less than 45 kJ/mol is preferably in the range of 5.0% by mass or less of the total amount of the non-aqueous ink composition, more preferably in the range of 3.0% by mass or less, even more preferably in the range of 1.0% by mass or less, and even more preferably in the range of 0.1% by mass or less.

The content of other organic solvents is not particularly limited, but the lower limit of the content of other organic solvents is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The upper limit of the content of other organic solvents is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[resin]
The non-aqueous ink composition according to the present embodiment may not contain a resin, but may contain a resin. By containing a resin, the fixing property, water resistance, and stretchability of the recording layer formed by the non-aqueous ink composition can be improved. Furthermore, the glossiness of the resulting recorded matter can be more effectively improved. Note that these resins are binder resins that form the so-called coating film (recording layer), and are distinguished from polymer dispersants that disperse color materials (pigments).

The resin is not particularly limited, but examples thereof include acrylic resins, polystyrene resins, polyester resins, vinyl chloride resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymer resins, polyethylene resins, polyurethane resins, rosin-modified resins, phenol resins, terpene resins, polyamide resins, vinyltoluene-α-methylstyrene copolymers, ethylene-vinyl acetate copolymers, cellulose resins, silicone resins, acrylamide resins, epoxy resins, or copolymer resins or mixtures thereof. Among these, those containing acrylic resins, vinyl chloride-vinyl acetate copolymer resins, cellulose resins, polyester resins, or polyurethane resins are preferred.

The acrylic resin is not particularly limited as long as it contains a (meth)acrylic acid ester monomer as the main component of the monomer. The acrylic resin may be a homopolymer of one type of radical polymerizable monomer, or a copolymer using two or more selected radical polymerizable monomers. In particular, the acrylic resin preferred for the oil-based ink composition according to the present embodiment is a homopolymer of methyl methacrylate, or a copolymer of methyl methacrylate and at least one compound selected from the group consisting of butyl methacrylate, ethoxyethyl methacrylate, and benzyl methacrylate. Examples of commercially available (meth)acrylic resins include "Paraloid B99N", "Paraloid B60", "Paraloid B66", and "Paraloid B82" manufactured by Rohm and Haas.

Vinyl chloride-vinyl acetate copolymer resin is a polymer of vinyl chloride monomer and vinyl acetate monomer. Examples of vinyl chloride-vinyl acetate copolymer resins include vinyl chloride-vinyl acetate copolymer, vinyl chloride/vinyl acetate/maleic acid copolymer, vinyl chloride/vinyl acetate/vinyl alcohol copolymer, vinyl chloride/vinyl acetate/hydroxyalkyl acrylate copolymer, and mixtures thereof. The above vinyl chloride-vinyl acetate copolymer resins can be obtained from Nissin Chemical Industry Co., Ltd. under the trade names Solvine C, CL, CNL, CLL, CLL2, C5R, TA2, TA3, A, AL, TA5R, M5, etc., and can be used in the present invention.

Vinyl chloride-vinyl acetate copolymer resin can be obtained by polymerizing vinyl chloride monomer and vinyl acetate monomer. The polymerization method may be any conventionally known polymerization method. The polymerization method is preferably emulsion polymerization or suspension polymerization, and more preferably suspension polymerization.

Cellulose-based resins are resins with a cellulose skeleton obtained by biologically or chemically introducing functional groups into cellulose as a raw material. Examples of cellulose-based resins include cellulose acetate alkylate resins such as cellulose acetate butyrate resin, cellulose acetate propionate resin, and cellulose acetate propionate butyrate resin, cellulose acetate resin, nitrocellulose resin, and mixtures thereof. The above cellulose resins can be obtained and used under the trade names "CAB551-0.01", "CAB551-0.2", "CAB553-0.4", "CAB531-1", "CAB381-0.1", "CAB381-0.5", "CAB381-2", "CAB381-20", "CAP504", "CAP482-0.5", etc., from EASTMAN.

The polyester resin contains at least a structural unit obtained by polycondensation of an alcohol component and a carboxylic acid component. The polyester resin may contain a modified polyester resin. The polyester resin may be obtained under the trade names of Toyobo Co., Ltd., such as "VYLON226", "VYLON270", "VYLON560", "VYLON600", "VYLON630", "VYLON660", "VYLON885", "VYLONGK250", "VYLONGK810", and "VYLON GK890", and Unitika Co., Ltd., such as "eliteUE-3200", "eliteUE-3285", "eliteUE-3320", "eliteUE-9800", and "eliteUE-9885".

The polyurethane resin contains at least a structural unit obtained by copolymerizing an alcohol component and an isocyanate component. The polyurethane resin may contain a polyurethane resin modified with polyester, polyether, or caprolactone. The polyurethane resin may be available under the trade names of Arakawa Chemical Industries Co., Ltd.'s "Uriano KL-424", "Uriano KL-564", "Uriano KL-593", "Uriano 3262", etc., or DIC Corporation's "Pandex 372E", "Pandex 390E", "Pandex 394E", "Pandex 304", "Pandex 305E", "Pandex P-870", "Pandex P-910", "Pandex P-895", "Pandex 4030", "Pandex 4110", etc.

The acrylic resin, vinyl chloride-vinyl acetate copolymer resin, cellulose resin, polyester resin, and polyurethane resin may be used alone, but it is preferable to use two of them in combination, and it is more preferable to use a resin in which an acrylic resin and a vinyl chloride-vinyl acetate copolymer resin are mixed. Depending on the content ratio of the acrylic resin and the vinyl chloride-vinyl acetate copolymer resin, it is possible to control the color development, drying properties, coating film properties, printability, and other requirements required of non-aqueous inks. When an acrylic resin and a vinyl chloride-vinyl acetate copolymer resin are mixed, the mixing ratio is not particularly limited and can be changed as appropriate.

The weight average molecular weight (relative molecular mass) of the resin is not particularly limited, but is preferably 5,000 or more, and more preferably 15,000 or more. The weight average molecular weight (relative molecular mass) is preferably 100,000 or less, and more preferably 50,000 or less. The relative molecular weight of the resin can be measured by conventional GPC (gel permeation chromatography).

The resin contained in the non-aqueous ink composition is preferably contained in an amount of 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, based on the total amount of the non-aqueous ink composition. The resin contained in the non-aqueous ink composition is preferably contained in an amount of 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 10.0% by mass or less, based on the total amount of the non-aqueous ink composition.

In addition, it is preferable that the resins contained in the non-aqueous ink composition according to this embodiment have an intrinsic viscosity of 90 mL/g or more at 25°C in a range of 5 mass % or less of the total amount of resin. This results in excellent printing performance such as continuous ejection stability, and can further effectively improve the gloss of the resulting recorded matter.

In this specification, the intrinsic viscosity can be determined by dispersing a target resin in a developing solvent, separating the molecules contained in the resin using a column packed with granular gel in GPC (gel permeation chromatography), determining the specific viscosity [η _SP ] ((η - η ₀ )/η ₀ (η ₀ : solvent viscosity, η: solution viscosity)) and concentration C, and extrapolating the concentration C to 0 (C → 0) in the formula Lim ([η _SP ]/C). The developing solvent is not particularly limited, and tetrahydrofuran, for example, can be used.

The content of resins with an intrinsic viscosity of 90 mL/g or more at 25°C is preferably 4.0% by mass or less of the total amount of resin, more preferably 3.5% by mass or less, and even more preferably 2.5% by mass or less.

[Colorant]
The non-aqueous ink composition according to the present embodiment may contain a coloring material. The coloring material is not particularly limited and may be a dye-based material or a pigment-based material, but it is preferable to use a pigment (pigment-based coloring material) from the viewpoint of good resistance such as water resistance and light resistance of the recorded matter. The pigment that can be used in the non-aqueous ink composition according to the present embodiment is not particularly limited, and examples thereof include organic pigments and inorganic pigments used in conventional ink compositions. These may be used alone or in combination of two or more types. The non-aqueous ink composition according to the present embodiment may not contain a coloring material.

When a pigment is used in the non-aqueous ink composition according to this embodiment, the dispersion stability of the pigment can be improved by using a dispersant or dispersion aid (pigment derivative) described below.

Specific examples of organic pigments include insoluble azo pigments, soluble azo pigments, dye derivatives, phthalocyanine organic pigments, quinacridone organic pigments, perylene organic pigments, perinone organic pigments, azomethine organic pigments, anthraquinone organic pigments (anthrone organic pigments), xanthene organic pigments, diketopyrrolopyrrole organic pigments, dioxazine organic pigments, nickel azo pigments, isoindolinone organic pigments, pyranthrone organic pigments, thioindigo organic pigments, condensed azo organic pigments, benzimidazolone organic pigments, quinophthalone organic pigments, isoindoline organic pigments, quinacridone solid solution pigments, perylene solid solution pigments, and other organic solid solution pigments such as lake pigments and carbon black.

Examples of organic pigments by color index (C.I.) number are C.I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 117, 120, 125, 128, 129, 130, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, 213, 214, C.I. C.I. Pigment Red 5, 7, 9, 12, 48, 49, 52, 53, 57:1, 97, 112, 122, 123, 146, 149, 150, 168, 177, 180, 184, 192, 202, 206, 208, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 269, 291, C.I. Pigment Orange 16, 36, 43, 51, 55, 59, 61, 64, 71, 73, C.I. Pigment Violet 19, 23, 29, 30, 37, 40, 50, C.I. Examples include C.I. Pigment Blue 15, 15:1, 15:3, 15:4, 15:6, 16, 22, 60, 64, C.I. Pigment Green 7, 36, 58, 59, 62, 63, C.I. Pigment Brown 23, 25, 26, and C.I. Pigment Black 7.

Specific examples of dyes that can be used in the non-aqueous ink composition according to this embodiment include azo dyes, benzoquinone dyes, naphthoquinone dyes, anthraquinone dyes, cyanine dyes, squarylium dyes, croconium dyes, merocyanine dyes, stilbene dyes, diarylmethane dyes, triarylmethane dyes, fluoran dyes, spiropyran dyes, phthalocyanine dyes, indigo dyes such as indigoid, fulgide dyes, nickel complex dyes, and azulene dyes.

Specific examples of inorganic pigments that can be used in the non-aqueous ink composition according to this embodiment include titanium oxide, barium sulfate, calcium carbonate, zinc oxide, barium carbonate, silica, talc, clay, synthetic mica, alumina, zinc oxide, lead sulfate, yellow lead, zinc yellow, red iron oxide (red iron (III) oxide), cadmium red, ultramarine, Prussian blue, chromium oxide green, cobalt green, amber, titanium black, aluminum, titanium, indium, synthetic iron black, inorganic solid solution pigments, etc.

In the non-aqueous ink composition according to the present embodiment, the average dispersion particle diameter of the pigment that can be contained is not particularly limited as long as it can produce the desired color. Although it varies depending on the type of pigment used, in order to obtain good dispersibility and dispersion stability of the pigment and sufficient coloring power, the volume average particle diameter is preferably in the range of 5 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. When the volume average particle diameter is equal to or greater than the above lower limit, the light resistance of the non-aqueous ink composition can be improved. When the volume average particle diameter is equal to or less than the above upper limit, the ejection stability of the inkjet can be improved when the non-aqueous ink composition is a non-aqueous inkjet ink composition that is ejected onto the surface of a substrate by an inkjet method. In this embodiment, the volume average particle diameter of the pigment is the volume average particle diameter (D50) measured under conditions of 25 ° C. using a particle size distribution measuring device (Microtrackbell Co., Ltd. particle size analyzer NANOTRACWAVE).

In addition, in an ink set including multiple non-aqueous ink compositions according to this embodiment, the volume average particle diameters of the pigments included in each non-aqueous ink composition may be the same or may have different relationships. For example, in the case of an ink set including a cyan ink and a magenta ink, which are non-aqueous ink compositions according to this embodiment, the volume average particle diameter of the pigment included in the cyan ink and the volume average particle diameter of the pigment included in the magenta ink may be the same or may be different.

In the non-aqueous ink composition according to this embodiment, the pigment content is not particularly limited as long as the desired image can be formed, and is adjusted as appropriate. Specifically, although it varies depending on the type of pigment, it is preferably 0.05% by mass or more of the total amount of the non-aqueous ink composition, and more preferably 0.1% by mass or more. It is preferably 20% by mass or less of the total amount of the non-aqueous ink composition, and more preferably 10% by mass or less. By having the pigment content in the range of 0.05% by mass or more or 20% by mass or less, it is possible to achieve an excellent balance between the pigment dispersion stability and coloring power.

The non-aqueous ink composition according to this embodiment is not particularly limited in the color to be recorded (printed), and coloring materials may be selected and combined according to the color of interest. Colors may be used in inks of various colors such as yellow, magenta, cyan, and black, as well as light magenta, light cyan, light black, orange, green, red, and white. In this case, coloring materials of the same color may be selected in an ink set that includes the non-aqueous ink composition according to this embodiment.

[Dispersant]
A dispersant may be used in the non-aqueous ink composition according to the present embodiment, if necessary. Any dispersant used in non-aqueous ink compositions may be used as the dispersant. A polymer dispersant may be used as the dispersant. Such dispersants have a main chain made of polyester, polyacrylic, polyurethane, polyamine, polycaprolactone, or the like, and have polar groups such as amino, carboxyl, sulfone, and hydroxyl groups as side chains. Examples of polyacrylic dispersants include Disperbyk-2000, 2001, 2008, 2009, 2010, 2020, 2020N, 2022, 2025, 2050, 2070, 2095, 2150, 2151, 2155, 2163, 2164, BYKJET-9130, 9131, 9132, 9133, 9151 (manufactured by BYK-Chemie), Efka PX4310, PX4320, PX4330, PA4401, 4402, PA4403, 4570, 7411, 7477, PX4700, PX4701 (manufactured by BASF), and TREPLUS. D-1200, D-1410, D-1420, MD-1000 (manufactured by Otsuka Chemical Co., Ltd.), FLOWRENE DOPA-15BHFS, 17HF, 22, G-700, 900, NC-500, GW-1500 (manufactured by Kyoeisha Chemical Co., Ltd.), and the like can be used. Examples of polycaprolactone-based dispersants include Ajisper PB821, PB822, and PB881 (manufactured by Ajinomoto Fine-Techno Co., Ltd.), Hinoact KF-1000, T-6000, T-7000, T-8000, T-8000E, and T-9050 (manufactured by Kawaken Fine Chemical Co., Ltd.), Solsperse 20000, 24000, 32000, 32500, 32550, 32600, 33000, 33500, 34000, 35200, 36000, 37500, 39000, 71000, 76400, 76500, 86000, 88000, J180, and J200 (manufactured by Lubrizol Corporation), and TEGO Dispers 652, 655, 685, 688, 690 (manufactured by Evonik Japan Co., Ltd.) and the like are used. Preferred dispersants include BYKJET-9130, 9131, 9132, 9133, 9151, Efka PX4310, PX4320, PX4330, PX4700, PX4701, Solsperse 20000, 24000, 32000, 33000, 33500, 34000, 35200, 39000, 71000, 76500, 86000, 88000, J180, J200, TEGO Dispers 655, 685, 688, 690, and the like. These can be used alone or in mixtures thereof.

The dispersant content is not particularly limited, but the lower limit of the dispersant content is preferably 0.1 mass% or more of the total amount of the non-aqueous ink composition, more preferably 0.5 mass% or more, and even more preferably 0.8 mass% or more. The dispersant content is not particularly limited, but the lower limit of the dispersant content is preferably 5.0 mass% or more of the total amount of the non-aqueous ink composition, more preferably 4.0 mass% or more, and even more preferably 3.0 mass% or more.

[Dispersion aid]
A dispersion aid may be used as necessary in the non-aqueous ink composition according to this embodiment. The dispersion aid is adsorbed to the surface of the colorant (pigment), and the functional group enhances the affinity with the organic solvent and dispersant in the non-aqueous ink composition, thereby improving the dispersion stability. As the dispersion aid, a known pigment derivative having a functional group such as an acidic group, a basic group, or a neutral group in the organic pigment residue can be used.

[Surfactant]
A surfactant may be added to the non-aqueous ink composition according to the present embodiment for the purpose of suppressing volatilization of the non-aqueous ink composition in devices such as nozzles and tubes, preventing solidification, and improving resolubility when solidified, as well as for the purpose of lowering surface tension and improving wettability with a recording medium (substrate). Examples of such surfactants include polyoxyalkylene alkyl ethers such as Nonion P-208, P-210, P-213, E-202S, E-205S, E-215, K-204, K-220, S-207, S-215, A-10R, A-13P, NC-203, and NC-207 (manufactured by Nippon Oil & Fats Co., Ltd.), Emulgen 106, 108, 707, 709, A-90, and A-60 (manufactured by Kao Corporation), and Flow Len G-70, D-90, TG-740W (Kyoeisha Chemical Co., Ltd.), Poem J-0081HV (Riken Vitamin Co., Ltd.), Adekatar NP-620, NP-650, NP-660, NP-675, NP-683, NP-686, Adekacol CS-141E, TS-230E (Adeka Corporation), etc., Solgen 30V, 40, TW-20, TW-80, Noigen CX-100 (Third As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, a specific example of which is BYK-340 (manufactured by BYK Japan KK), and as the silicone-based surfactant, it is preferable to use a polyester-modified silicone or a polyether-modified silicone, specific examples of which are BYK-313, 315N, 322, 326, 331, 347, 348, BYK-UV3500, 3510, 3530, 3570 (all manufactured by BYK Japan KK), and specific examples of the acetylene glycol-based surfactant include Surfynol (registered trademark) 82, 104, 465, 485, TG (all manufactured by Air Products Japan KK), Olfine (registered trademark) STG, E1010 (all manufactured by Nissin Chemical Industry Co., Ltd.), and the like.

The surfactant is not limited to the above, and any of anionic, cationic, amphoteric, or nonionic surfactants can be used, and may be selected appropriately according to the purpose of addition.

[Other ingredients]
The non-aqueous ink composition according to the present embodiment may contain known additives as optional components, such as stabilizers, such as antioxidants and ultraviolet absorbers, epoxidized products, polycarboxylic acids, surface conditioners, slipping agents, leveling agents (acrylic or silicone-based), defoamers, pH adjusters, bactericides, preservatives, deodorants, charge regulators, and wetting agents. Specific examples of antioxidants include hindered phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and hydrazine-based antioxidants. Specific examples include BHA (2,3-butyl-4-oxyanisole) and BHT (2,6-di-t-butyl-p-cresol). Benzophenone-based compounds or benzotriazole-based compounds can be used as ultraviolet absorbers. Specific examples of the epoxidized product include epoxy glyceride, epoxy fatty acid monoester, and epoxy hexahydrophthalate, and specific examples thereof include Adeka Cizer O-130P and Adeka Cizer O-180A (manufactured by ADEKA CORPORATION), etc. Specific examples of the polyvalent carboxylic acid include citric acid and maleic acid, etc.

2. Method for producing ink composition
The ink composition according to the present embodiment can be produced by mixing the alkylamide solvent (a), the organic solvent (b) having an enthalpy of evaporation (EOV) of 45 kJ/mol or more, and each main component (e.g., resin, coloring material, etc.) using a paint shaker. At this time, each component may be dispersed using zirconia beads. The obtained non-aqueous ink composition may be degassed as necessary to adjust the amount of dissolved oxygen and dissolved nitrogen to a desired amount.

It is also preferable to dry the organic solvent in advance. By drying the organic solvent in advance, the amount of water contained in the non-aqueous ink composition can be reduced. Examples of methods for drying the organic solvent include a method of spraying an inert gas (e.g., nitrogen gas) dried under an inert gas atmosphere such as nitrogen for a predetermined period of time, a method of purifying the organic solvent by distillation, a method of passing the organic solvent through a semi-permeable membrane that selectively allows water to pass through, and a method of selectively adsorbing water mixed in the organic solvent to a water adsorbent that adsorbs water.

3. Recording method using ink composition
The recording method according to the present embodiment is a recording method in which the above-mentioned non-aqueous ink composition is ejected onto the surface of a substrate by an inkjet method. The above-mentioned non-aqueous ink composition is capable of obtaining a recorded matter that exhibits excellent surface dryness and blocking resistance and excellent glossiness, and the recording method according to the present embodiment can also obtain a recorded matter that exhibits excellent surface dryness and blocking resistance and excellent glossiness. The method of ejecting by the inkjet method is not particularly limited and may be a piezo method using a piezoelectric element or a thermal method using a heating element.

The non-aqueous ink composition that has landed on the substrate (recording medium) is preferably heated by a heating mechanism provided in the inkjet recording device. This makes it possible to dry not only the alkylamide solvent (a) but also the organic solvent (b) with an evaporation enthalpy (EOV) of 45 kJ/mol or more by drying the non-aqueous ink composition that has landed on the substrate (recording medium), thereby making it possible to further improve the surface dryness and blocking resistance of the recorded material. The same applies to the manufacturing method of the recorded material described below.

4. Manufacturing method of recorded matter
The recording method using the ink composition described above can also be defined as a method for producing a recorded matter. The method for producing a recorded matter according to the present embodiment also makes it possible to obtain a recorded matter that is excellent in surface dryness and blocking resistance and exhibits excellent gloss.

5. Records
Each layer constituting the recorded matter produced by the method for producing a recorded matter according to the embodiment described above will be described.

[Medium (recording medium)]
The substrate (recording medium) that can be used in the recording method according to the present embodiment is not particularly limited, and may be a non-absorbent substrate such as a resin substrate or a metal plate glass, an absorbent substrate such as paper or fabric, or a substrate that has been subjected to a surface coating such as a substrate having a receiving layer, and various substrates can be used.

Among these, the non-aqueous ink composition does not contain water, and therefore the surface is preferably made mainly of resin. In particular, the non-aqueous ink composition contains an alkylamide solvent (a) that exhibits permeability to resin substrates, so that the printing on a medium (recording medium) whose surface is made of resin is less likely to bleed, resulting in clearer printing. Examples of resins include polyvinyl chloride polymers, acrylic, PET, polycarbonate, PE, PP, and the like. The ink composition may also be used for a resin substrate (so-called resin substrate for lamination) that is intended to have a film laminated to the recording surface of the recording material. In particular, a substrate (recording medium) whose surface is made of a hard or soft polyvinyl chloride polymer is preferred. Examples of substrates (recording media) whose surface is made of polyvinyl chloride polymer include polyvinyl chloride substrates (films or sheets).

[Recording layer]
The recording layer is a layer formed by volatilization of the solvent contained in the non-aqueous ink composition, and is a layer on which a desired image is formed. By ejecting the non-aqueous ink composition, a recorded matter exhibiting excellent surface drying properties and blocking resistance and excellent gloss can be obtained.

The layer formed by the evaporation of the solvent contained in the non-aqueous ink composition may be formed from multiple layers. For example, a layer of a color ink (e.g., yellow, magenta, cyan, black) of the non-aqueous ink composition may be formed on a layer of a white ink of the non-aqueous ink composition.

[Other layers]
The recorded matter according to the present embodiment may further include a layer having a desired function on the upper surface of the decorative layer. For example, an overcoat layer containing at least one of a resin and a wax may be formed for the purpose of further imparting abrasion resistance and glossiness to the recorded matter. In addition, a layer expressing a rough surface (matte surface) may be formed on the surface by including a filler or changing the film thickness in pixel units. In addition, in order to impart weather resistance to the recorded matter, a weather-resistant layer containing an ultraviolet absorber, a light stabilizer, etc., or a glittering layer containing a glittering pigment, etc. may be formed.

In the recorded matter according to the present embodiment, a recorded matter including a recording layer formed from the above non-aqueous ink composition has been described, but for example, the above non-aqueous ink composition may be ejected onto a recording layer formed from a conventionally known ink composition to form a layer having a desired function. Also, the above non-aqueous ink composition may be ejected onto a recording layer formed from the above non-aqueous ink composition to form a layer having a desired function.

<6. Inkjet recording device>
The inkjet recording device for ejecting the non-aqueous ink composition by an inkjet method may be a conventionally known inkjet recording device, such as an inkjet printer such as VersaArt RE-640 manufactured by Roland DG Corporation.

As an example of the configuration of an inkjet recording device, an on-carriage type, serial printer type inkjet recording device will be described, but an inkjet recording device capable of carrying out the recording method according to this embodiment may be an off-carriage type inkjet recording device in which the ink cartridge is fixed externally, or a line printer type inkjet recording device in which the inkjet head does not move and ejects the ink composition onto a recording medium (substrate).

The inkjet recording device preferably includes a heating mechanism and a fixing mechanism for fixing the substrate. The heating mechanism included in the inkjet recording device controls the substrate surface temperature and dries the non-aqueous ink composition that has landed on the substrate (recording medium), thereby making it possible to volatilize the organic solvent contained in the non-aqueous ink composition. In particular, since the non-aqueous ink composition contains an organic solvent (b) that is relatively difficult to volatilize and has an enthalpy of evaporation (EOV) of 45 kJ/mol or more, it is possible to quickly volatilize this organic solvent (b) by the heating mechanism.

Furthermore, the fixing mechanism for fixing the substrate makes it possible to dry the non-aqueous ink composition while the substrate (recording medium) is fixed, and it is possible to prevent the substrate from warping due to heating, which can lead to uneven heating. This makes it possible to effectively dry the non-aqueous ink composition that has landed on the substrate (recording medium).

The heating mechanism provided in the inkjet recording device may be a pre-heater, platen heater, after-heater, etc., or may be a mechanism for blowing hot air onto the recording material. In addition, a combination of multiple such heating mechanisms may be used.

The surface temperature of the substrate heated by the heating mechanism is not particularly limited as long as it can volatilize the organic solvent contained in the non-aqueous ink composition, and the lower limit of the substrate surface temperature is preferably 20°C or higher, more preferably 30°C or higher, and even more preferably 40°C or higher. The upper limit of the substrate surface temperature is preferably 70°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower.

The fixing mechanism for fixing the substrate is not particularly limited and may be a fixing mechanism that fixes the substrate with a specified jig or a fixing mechanism that sucks and adsorbs the substrate by negative pressure.

The inkjet head that ejects the non-aqueous ink composition is not particularly limited and may be a piezoelectric inkjet head using a piezoelectric element or a thermal inkjet head using a heating element.

The inkjet recording device may also be configured to include a plastic tube that connects a container (ink cartridge, bottle, etc.) that stores the non-aqueous ink composition to an inkjet head that ejects the non-aqueous ink composition, and the non-aqueous ink composition is supplied to the inkjet head through the plastic tube and ejected by an inkjet method. If the non-aqueous ink composition is present in the plastic tube, some of the organic solvent contained in the non-aqueous ink composition may volatilize. This may change the amount of organic solvent contained in the non-aqueous ink composition at the inkjet ejection stage, and the desired characteristics may not be obtained.

In particular, the alkylamide solvent (a) contained in the non-aqueous ink composition volatilizes relatively less when present in a plastic tube compared to other organic solvents. The amount of evaporation of an organic solvent in a plastic tube does not necessarily correlate with the volatility parameters of the organic solvent itself, such as the boiling point, flash point, or evaporation enthalpy of the organic solvent. This is because the permeability of plastics differs depending on the type of organic solvent, and the evaporation rate in a sealed low-density polyethylene tube is rather due to the permeability of plastics, specifically, it is a parameter due to the chemical structure, molecular weight, compatibility, etc. of the organic solvent.

Since alkylamide-based solvents are solvents that volatilize in a relatively small amount inside a plastic tube, a non-aqueous ink composition that contains an alkylamide-based solvent can be inkjet-ejected while maintaining the amount of organic solvent contained in the non-aqueous ink composition.

The amount of organic solvent that evaporates in a plastic tube can be determined by filling a low-density polyethylene tube (a 12-cm-long tube of a polyethylene tube hose (model number: 6-608-03, low-density polyethylene (PE-LD) with an inner diameter of 3 mm and an outer diameter of 5 mm, manufactured by AS ONE Corporation) with the organic solvent, sealing it, storing it at 50°C for one week, and measuring the amount of evaporation after storage. For example, the amount of evaporation of diethylene glycol dimethyl ether is 68% by mass, diethylene glycol methyl ethyl ether is 58% by mass, diethylene glycol diethyl ether is 54% by mass, and dipropylene glycol dimethyl ether is 59% by mass, whereas N,N-diethylformamide is 11% by mass, N,N-diethylpropanamide is 12% by mass, and N,N-diethylacetamide is 13% by mass. This shows that alkylamide solvents are solvents that evaporate less in a plastic tube.

The material of the plastic tube is not particularly limited, but examples include polyolefin resins such as polyethylene resins, ethylene propylene diene rubber, nylon, polyurethane, PTFE, etc. Among these, polyethylene resins and ethylene propylene diene rubber are preferable.

As described above, the inkjet recording device according to this embodiment can be used with inks of various colors, such as yellow, magenta, cyan, and black, as well as light magenta, light cyan, light black, orange, green, red, and white, and there are no particular limitations on the order of colors to be printed or the position and configuration of the head. The inkjet recording device according to this embodiment may or may not include a winding mechanism for the recording medium (substrate), a drying mechanism for drying the substrate surface, and an ink circulation mechanism.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way.

1. Preparation of resin (1) Acrylic resin A mixture of 150 g of methyl methacrylate, 50 g of butyl methacrylate, and a predetermined amount of t-butylperoxy-2-ethylhexanoate (polymerization initiator) was dropped into 300 g of diethylene glycol diethyl ether kept at 100 ° C. over 1.5 hours. After the dropwise addition, the mixture was reacted at 100 ° C. for 2 hours and then cooled to obtain a colorless and transparent polymer solution of methyl methacrylate. Then, the solvent was sufficiently distilled off from this polymer solution to obtain a polymer of methyl methacrylate. At this time, the amount of t-butylperoxy-2-ethylhexanoate, which is the polymerization initiator, was changed to control the weight average molecular weight of methyl methacrylate (acrylic resin) to 30,000 to 105,000 (the mass of the polymerization initiator used at this time is shown in Table 1 below. In Table 1, it is indicated as "amount of initiator".).

(2) Vinyl chloride-vinyl acetate copolymer resin After nitrogen replacement, an autoclave equipped with a stirrer was charged with 100 parts by mass of deionized water, 40 parts by mass of methanol, 32 parts by mass of vinyl chloride, 5 parts by mass of vinyl acetate, 0.2 parts by mass of glycidyl methacrylate, 3.55 parts by mass of hydroxypropyl acrylate, 0.1 parts by mass of hydroxypropyl methylcellulose (suspending agent), 0.026 parts by mass of di-2-ethylhexyl peroxydicarbonate (polymerization initiator), and a predetermined amount of di-3,5,5-trimethylhexanol peroxide (polymerization initiator), and the temperature was raised to 63° C. with stirring under a nitrogen gas atmosphere. Immediately after the temperature reached 63° C., a mixture of 48 parts by mass of vinyl chloride over 6 hours, 0.6 parts by mass of glycidyl methacrylate, and 10.65 parts of hydroxypropyl acrylate was continuously injected over 5.4 hours to carry out a copolymerization reaction. When the internal pressure of the autoclave reached 0.3 MPa, the residual pressure was released, and the autoclave was cooled to remove the resin slurry, which was then filtered and dried to obtain a vinyl chloride copolymer resin. The amount of di-3,5,5-trimethylhexanol peroxide used as the polymerization initiator was changed to control the weight average molecular weight of the vinyl chloride-vinyl acetate copolymer resin to 40,000 to 75,000 (the mass of the polymerization initiator used is shown in Table 1 below, and is indicated as "amount of initiator" in Table 1).

(3) Cellulosic Resin Commercially available cellulose resins (CAB551-0.01 and CAB553-0.4 manufactured by Eastman Chemical Co.) were used.

Table 1 shows the weight average molecular weight (relative molecular mass) of each resin (acrylic resin, vinyl chloride-vinyl acetate copolymer resin, cellulose resin) and the proportion of resins having an intrinsic viscosity of 90 mL/g or more at 25°C. The weight average molecular weight (relative molecular mass) was measured by GPC (gel permeation chromatography). The proportion of resins having an intrinsic viscosity of 90 mL/g or more was determined by connecting a viscosity detector (ViscoStarIII manufactured by WYATT) and a refractive index detector (Optilab T-rEX manufactured by WYATT) to a Shimadzu SEC (GPC) system, using tetrahydrofuran as a developing solvent, first passing a sample through a column heated to 40°C in the Shimadzu SEC (GPC) system, and then cooling the passed-through material to 25°C to determine the specific viscosity [η _SP ] using the viscosity detector, and the concentration C using the refractive index detector, and extrapolating the concentration C to 0 in Lim ([η _SP ]/C) to determine the intrinsic viscosity.

2. Preparation of non-aqueous ink compositions Non-aqueous ink compositions of the examples and comparative examples were prepared by dispersing each of the organic solvents, resins, dispersants, and pigments (coloring materials) in the proportions shown in the table below. Specifically, the non-aqueous ink compositions were prepared by dispersing each of the components with zirconia beads using a paint shaker. The units are % by mass.

3. Rating 1
(Glossiness)
The glossiness of the non-aqueous ink compositions of the Examples and Comparative Examples was evaluated. Specifically, the non-aqueous ink compositions of the Examples and Comparative Examples were printed on a recording medium (glued polyvinyl chloride film (IMAGin JT5829R: manufactured by MACtac)) in a high quality print mode (1440x720dpi) at a substrate surface temperature of 40°C by an inkjet method using an inkjet printer (product name VersaArt RE-640, manufactured by Roland DG Corporation)) at a solid area at a substrate surface temperature of 40°C, and the print was dried in a 60°C oven for 5 minutes, after which the 20° glossiness of the print was measured. The glossiness was measured with a handy glossmeter PhopointIQ-S (manufactured by Konica Minolta) (referred to as "glossiness" in the table).
Evaluation criteria: Evaluation 5: 20° gloss is 70 or more Evaluation 4: 20° gloss is 65 or more and less than 70 Evaluation 3: 20° gloss is 55 or more and less than 65 Evaluation 2: 20° gloss is 50 or more and less than 55 Evaluation 1: 20° gloss is less than 50

(Surface dryness)
The non-aqueous ink compositions of the Examples and Comparative Examples were evaluated for surface drying properties. Specifically, a solid image was printed on a recording medium (adhesive polyvinyl chloride film (IMAGin JT5829R: manufactured by MACtac)) in high quality print mode (1440 x 720 dpi) in the same manner as in the gloss evaluation above, and the time until the image dried at 40°C was measured (referred to as "surface drying properties" in the table).
Evaluation Criteria Evaluation 5: Dries in less than 2 minutes.
Rating 4: Dries in 2 to 4 minutes.
Rating 3: Dries in 4 minutes or more and less than 6 minutes.
Rating 2: Dries in 6 minutes or more and less than 8 minutes.
Rating 1: Dries in 8 minutes or more.

(Blocking resistance)
The blocking resistance of the non-aqueous ink compositions of the Examples and Comparative Examples was evaluated. Specifically, in the same manner as in the gloss evaluation above, a solid portion was printed on a recording medium (glued polyvinyl chloride film (IMAGin JT5829R: manufactured by MACtac)) in high quality print mode (1440x720 dpi) at a substrate surface temperature of 40°C, the recorded matter was rolled up and left for 24 hours, and then unrolled, and the offset to the back surface of the film that overlapped the recorded matter surface and the recorded matter surface were evaluated (represented as "blocking resistance" in the table).
Evaluation Criteria Evaluation 5: After winding, there is no offset to the back surface, and no roughness on the surface of the recorded material.
Evaluation 4: There is no offset to the back surface after winding, but slight roughness is observed on the surface of the recorded material, but the design is not impaired.
Evaluation 3: After winding, slight offset was observed to the back surface, and slight marks were observed on the surface of the recorded material.
Evaluation 2: After winding, transfer to the back surface was clearly observed, and marks were observed on the surface of the recorded material.
Evaluation 1: After winding, significant ink transfer to the back surface was observed, and the design of the printed matter surface was significantly impaired.

(Intermittent ejection)
The non-aqueous ink compositions of the Examples and Comparative Examples were evaluated for intermittent ejection properties. Specifically, in the same manner as in the gloss evaluation described above, intermittent printing was performed on a recording medium (adhesive polyvinyl chloride film (IMAGin JT5829R: manufactured by MACtac)) at room temperature over a long period of time in a bidirectional high-speed printing mode (360x720 dpi) with a substrate surface temperature of 40°C, and the recording medium was observed for the presence or absence of missing dots, deflection of ink flight, and ink scattering, and the number of occurrences was counted and evaluated (represented as "intermittent ejection properties" in the table).
Evaluation Criteria Evaluation 5: Within a 24-hour test period, the occurrence of missing dots, ink flight deviation, or ink scattering occurred less than 10 times.
Evaluation 4: During a 24-hour test period, the occurrence of missing dots, ink flight deviation, or ink scattering occurred 10 or more times but less than 20 times.
Evaluation 3: During a 24-hour test period, the occurrence of missing dots, ink flight deviation, or ink scattering occurred 20 or more times but less than 30 times.
Evaluation 2: During a 24-hour test period, the occurrence of missing dots, ink flight deviation, or ink scattering occurred 30 or more times but less than 40 times.
Evaluation 1: Missing dots, deviation in ink flight, or ink scattering occurred 40 or more times within a 24-hour test period.

(Filled in solid)
The non-aqueous ink compositions of the Examples and Comparative Examples were evaluated for solid filling. Specifically, in the same manner as in the gloss evaluation described above, printing was performed on a recording medium (adhesive polyvinyl chloride film (IMAGin JT5829R: manufactured by MACtac)) in a bidirectional high-speed printing mode (360 x 720 dpi) at a substrate surface temperature of 40°C, and filling (whiteout) of the solid printed area was confirmed (represented as "solid filling" in the table).
Evaluation criteria Evaluation 5: A uniform solid is formed Evaluation 4: No white spots are visible to the naked eye, but slight color unevenness is visible, but the design is not impaired Evaluation 3: No white spots are visible to the naked eye, but color unevenness is visible Evaluation 2: White spots are visible Evaluation 1: Significant white spots are visible, and a decrease in the sense of density is observed.

(Bleeding)
The non-aqueous ink compositions of the Examples and Comparative Examples were evaluated for bleeding. Specifically, in the same manner as in the gloss evaluation, an image having 6 pt characters of a different color in a solid area of each color was printed on a recording medium (glued polyvinyl chloride film (IMAGin JT5829R: manufactured by MACtac)) in high quality print mode (1440x720 dpi) at a substrate surface temperature of 40°C, and the resulting print was dried in an oven at 60°C for 5 minutes, after which bleeding of the print was observed visually and with a magnifying glass (x10) (referred to as "Bleeding" in the table).
Evaluation Criteria Evaluation 5: No ink bleeding was observed when observed through a magnifying glass.
Rating 4: No ink bleeding was observed with the naked eye, and 6 pt characters were clear.
Evaluation 3: Slight bleeding of the ink was visually observed, but the design was not impaired.
Rating 2: Ink bleeding was observed with the naked eye, but 6 pt characters were legible.
Evaluation 1: Noticeable ink bleeding was visually observed, and 6 pt characters were not visible.

(Material suitability)
The non-aqueous ink compositions of the Examples and Comparative Examples were evaluated for suitability for components (suitability for inkjet head components). Specifically, 0.2 g of a cured product of an epoxy adhesive (two-component curing epoxy adhesive "1500", manufactured by Cemedine Co., Ltd.) used for inkjet head components, dried at 60°C for one day, was immersed in the ink compositions of the Examples and Comparative Examples and left at 60°C for one week, and an immersion test was performed to measure the weight change of the cured product (represented as "suitability for components" in the table).
Evaluation criteria: Evaluation 5: The weight change rate is less than 3%, and there is no deterioration of the epoxy adhesive material.
Evaluation 4: The weight change rate is 3% or more and less than 5%, and there is no deterioration of the epoxy adhesive material.
Evaluation 3: The weight change rate is 5% or more and less than 10%, and there is no deterioration of the epoxy adhesive material.
Evaluation 2: The weight change rate is 10% or more and less than 15%, and there is no deterioration of the epoxy adhesive material.
Rating 1: The weight change rate is 15% or more and/or the epoxy adhesive material is deteriorated.

In the table, "BTG" stands for triethylene glycol mono-n-butyl ether.

In the table, "BTeG" stands for tetraethylene glycol monobutyl ether.

In the table, "BHeG" stands for hexaethylene glycol monobutyl ether.

In the table, "MFTG" stands for tripropylene glycol monomethyl ether.

In the table, "MFDG" stands for dipropylene glycol monomethyl ether.

In the table, "DEGDBE" stands for diethylene glycol dibutyl ether.

In the table, "DEGMBEA" stands for diethylene glycol mono-n-butyl ether acetate.

In the table, "PC" stands for propylene carbonate.

In the table, "DESU" stands for diethyl succinate.

In the table, "EL" stands for ethyl lactate.

In the table, "3-MBOH" stands for 3-methoxybutanol.

In the table, "MOZ" stands for 3-methyl-2-oxazolidinone.

In the table, "CATE" stands for triethyl citrate.

In the table, "ECL" stands for ε-caprolactone.

In the table, "DEF" stands for N,N-diethylformamide.

In the table, "DEPA" stands for N,N-diethylpropionamide.

In the table, "DEAA" stands for N,N-diethylacetamide.

In the table, "DMF" stands for N,N-dimethylformamide.

In the table, "MEDG" stands for diethylene glycol methyl ethyl ether.

In the table, "DEDG" stands for diethylene glycol diethyl ether.

In the table, "DMFDG" stands for dipropylene glycol dimethyl ether.

In the table, "PMA" stands for propylene glycol monomethyl ether acetate.

In the table, "GBL" stands for gamma-butyrolactone.

In the table, "M100" is N,N-dimethyl-β-methoxypropionamide.

In the table, "ML" stands for methyl lactate.

In the table, "Solsperse 32000" is a polycaprolactone-based dispersant manufactured by Lubrizol Corporation.

In the table, "Solsperse 33000" is a polycaprolactone-based dispersant manufactured by Lubrizol Corporation.

As can be seen from Tables 2 to 9, the non-aqueous ink composition of the embodiment, which contains an alkylamide solvent (a) and an organic solvent (b) with an evaporation enthalpy (EOV) of 45 kJ/mol or more, can produce recorded materials that have excellent surface drying properties and blocking resistance, as well as excellent gloss.

In particular, among the non-aqueous ink compositions of Examples 1 to 8, which vary the content of organic solvent (b) with an enthalpy of evaporation (EOV) of 45 kJ/mol or more, Examples 3 to 8, in which the content of organic solvent (b) is 5% by mass or more of the total amount of the non-aqueous ink composition, exhibited particularly excellent glossiness. Furthermore, Examples 1 to 5, in which the content of organic solvent (b) is 15% by mass or less of the total amount of the non-aqueous ink composition, were able to obtain recorded matter with excellent surface drying properties, and bleeding of the print was further reduced.

In addition, in the non-aqueous ink compositions of Examples 9 to 17 in which the content of alkylamide solvent (a) was changed, Examples 11 to 17 in which the content of alkylamide solvent (a) was 5% by mass or more of the total amount of the non-aqueous ink composition were able to obtain records with excellent surface drying properties. And Examples 12 to 17 in which the content of alkylamide solvent (a) was 10% by mass or more of the total amount of the non-aqueous ink composition were able to obtain records with even less bleeding of the prints. Furthermore, Examples 9 to 13 in which the content of alkylamide solvent (a) was 45% by mass or less of the total amount of the non-aqueous ink composition were able to obtain good gloss.

In addition, the non-aqueous ink compositions of Examples 18 to 30, in which the type of organic solvent (b) with an enthalpy of evaporation (EOV) of 45 kJ/mol or more was changed, also achieved a good balance between surface drying properties and glossiness.

In addition, in the non-aqueous ink compositions of Examples 42 to 58, in which the content of the resin with an intrinsic viscosity of 90 mL/g or more at 25°C was changed, the non-aqueous ink compositions of Examples in which the content of the resin with an intrinsic viscosity of 90 mL/g or more at 25°C was in the range of 5 mass% or less of the total amount of resin showed improved solid filling and intermittent ejection properties, even when compared with the non-aqueous ink compositions of Examples in which the content of the resin with an intrinsic viscosity of 90 mL/g or more at 25°C was in the range of more than 5 mass%.

On the other hand, in Comparative Examples 1 to 3, which do not contain an organic solvent (b) with an enthalpy of evaporation (EOV) of 45 kJ/mol or more, the gloss of the resulting recorded matter was reduced, and the intermittent ejection property was also deteriorated. In particular, in Comparative Example 3, which contains γ-butyrolactone (lactone-based solvent), the gloss of the recording surface of the resulting recorded matter was particularly deteriorated. In Comparative Example 4, which does not contain an alkylamide-based solvent (a) and does not contain an organic solvent that penetrates into the resin substrate, the surface drying property of the resulting recorded matter was reduced, and bleeding occurred. In Comparative Example 5, which contains γ-butyrolactone (lactone-based solvent) and an organic solvent (b) with an enthalpy of evaporation (EOV) of 45 kJ/mol or more, offset (anti-blocking) occurred on the back surface that overlapped the surface of the recorded matter. In Comparative Example 6, which contains N,N-dimethyl-β-methoxypropionamide, the member suitability was deteriorated.

4. Rating 2
The non-aqueous ink composition of Example 4 was ejected by the inkjet method, and the "bleeding" and "solid coverage" were evaluated in the same manner as above. At this time, the heating mechanism and the fixing mechanism for fixing the substrate, which are provided in the inkjet recording device, were switched on and off as shown in Table 10 below.

As can be seen from Table 10, by using an inkjet recording device equipped with a heating mechanism and a fixing mechanism for fixing the substrate, turning on each mechanism, and drying the non-aqueous ink composition with the substrate (recording medium) fixed by the fixing mechanism for fixing the substrate, and then ejecting the non-aqueous ink composition containing an alkylamide solvent (a) and an organic solvent (b) having an enthalpy of evaporation (EOV) of 45 kJ/mol or more by the inkjet method, the "bleeding" and "solid coverage" of the resulting recorded matter can be improved.

Claims (11)

A non-aqueous ink composition containing an organic solvent and ejected by an inkjet method,
The organic solvent is
An alkylamide solvent (a);
an organic solvent (b) having an enthalpy of vaporization (EOV) of 45 kJ/mol or more and different from the alkylamide-based solvent (a) ;
Contains
The alkylamide solvent (a) contains an amide solvent represented by the following formula (2):
Non-aqueous ink compositions.

(In formula (1), R ₁ is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R _{2 and} R ₃ each independently represent an alkyl group having 2 to 4 carbon atoms.) The non-aqueous ink composition according to claim 1 , wherein the organic solvent (b) contains at least one selected from the group consisting of glycol ether dialkyls, glycol ether monoalkyls, acetates, cyclic esters, carbonates, dibasic acid esters, lactates, amides, and alcohols. The content of the organic solvent (b) is in the range of 1% by mass to 30% by mass of the total amount of the non-aqueous ink composition.
The non-aqueous ink composition according to claim 1 or 2. The alkylamide solvent (a) contains at least one selected from the group consisting of N,N-diethylformamide, N,N-diethylpropanamide, and N,N-diethylacetamide.
The non-aqueous ink composition according to any one of claims 1 to 3 . The content of the alkylamide solvent (a) is in the range of 1% by mass to 90% by mass of the total amount of the non-aqueous ink composition.
The non-aqueous ink composition according to any one of claims 1 to 4 . Further containing resin,
The non-aqueous ink composition according to claim 1 , wherein the resin has an intrinsic viscosity of 90 mL/g or more at 25° C. in an amount of 5% by mass or less based on the total amount of the resin. The non-aqueous ink composition according to claim 1 , which is ejected by an inkjet method using an inkjet recording apparatus equipped with a heating mechanism and a fixing mechanism for fixing a substrate. The non-aqueous ink composition according to claim 1 , which is ejected by an ink-jet method through a plastic tube using an ink-jet recording apparatus equipped with the plastic tube. A recording method comprising discharging the non-aqueous ink composition according to claim 1 onto a surface of a substrate by an inkjet system. A method for producing a recorded matter, comprising ejecting the nonaqueous ink composition according to claim 1 onto a surface of a substrate by an inkjet system. A recorded matter, comprising a recording layer of the non-aqueous ink composition according to any one of claims 1 to 8 formed on the surface of a substrate.