JP6863869B2 - Oil-based inkjet ink - Google Patents

Description

The present invention relates to an oil-based inkjet ink.

The inkjet recording method injects highly fluid inkjet ink as droplets from a fine nozzle and records an image on a recording medium placed facing the nozzle, enabling high-speed printing with low noise. Therefore, it has spread rapidly in recent years. As inks used in such an inkjet recording method, water-based inks containing water as a main solvent, ultraviolet curable inks (UV inks) containing a high content of polymerizable monomers as main components, and wax as main components are high. A so-called non-aqueous ink containing a non-aqueous solvent as a main solvent is known as well as a hot melt ink (solid ink) contained in a content. Non-aqueous inks can be classified into solvent inks (solvent-based inks) in which the main solvent is a volatile organic solvent and oil-based inks (oil-based inks) in which the main solvent is a low-volatile or non-volatile organic solvent. The solvent ink dries on the recording medium mainly by evaporation of the organic solvent, whereas the oil-based ink dries mainly by penetrating into the recording medium.

Since the color material of the ink used in the inkjet recording method is excellent in light resistance, weather resistance, and water resistance required for high-quality printing, the number of inks using a pigment as a color material tends to increase.
Among the pigments used for oil-based inks, there is a dyed lake pigment. The dyed lake pigment is a pigment in which a water-soluble dye is insolubilized and fixed to an extender pigment, and various hues derived from the dye can be obtained, and also excellent in light resistance, weather resistance and water resistance.

In Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-19766), a xanthene pigment, which is one of the dyed lake pigments, is used in order to obtain a printed matter having high concentration and high saturation in a non-aqueous inkjet ink. The ink of Patent Document 1 uses a non-aqueous solvent that is a combination of an ester solvent, an alcohol solvent, and a non-polar solvent.

Since there are various combinations of pigments and non-aqueous solvents in oil-based inks, dyed lake pigments are mentioned as an example of general pigments, and silicone oil is mentioned as an example of non-aqueous solvents. .. See Patent Document 2 (Japanese Unexamined Patent Publication No. 2005-60567), Patent Document 3 (Japanese Unexamined Patent Publication No. 2006-315363), Patent Document 4 (Japanese Unexamined Patent Publication No. 2006-307107), and the like.

In Patent Document 5 (Japanese Unexamined Patent Publication No. 2004-217703), ink stability and nozzles are provided by a non-aqueous pigment ink for inkjet, which contains a silicone-based solvent and a pigment, and further contains a specific modified silicone oil as a dispersant. It is proposed to improve clogging and clear file deformation.
In Patent Document 6 (Japanese Unexamined Patent Publication No. 4-248879), an inkjet recording ink containing 2 to 95 wt (%) of a silicone-based solvent having a boiling point of at least 100 ° C. to 250 ° C. and a coloring material insoluble in the solvent is used. It is proposed that good print quality can be obtained regardless of the paper quality, sufficient print resistance can be obtained within a few seconds after printing, and a clear image without color mixing can be obtained in a color image.

In Patent Document 7 (Japanese Unexamined Patent Publication No. 4-161467), ink for an inkjet printer using an insulating solvent having a siloxane bond in the molecular skeleton enables clear printing at high density and has scratch resistance. Moreover, it is proposed that stable discharge becomes possible.

Japanese Unexamined Patent Publication No. 2014-19766 Japanese Unexamined Patent Publication No. 2005-60567 Japanese Unexamined Patent Publication No. 2006-315363 Japanese Unexamined Patent Publication No. 2006-307107 Japanese Unexamined Patent Publication No. 2004-217703 Japanese Unexamined Patent Publication No. 4-248879 Japanese Unexamined Patent Publication No. 4-161467

In Patent Document 1, a non-aqueous ink is produced by blending a xanthene-based pigment with a non-aqueous solvent that is a combination of an ester-based solvent, an alcohol-based solvent, and a non-polar solvent. Such a non-aqueous solvent has a problem that the drying speed of the printed matter becomes slow after printing and the fixability of the printed image immediately after printing is poor. In addition, xanthene pigments may be dyed in polar solvents such as ester solvents and alcohol solvents, and the dyed components cause bleeding at the boundary between the printed area and the unprinted area of the printed matter. However, there is a problem that the light resistance is lowered.

The silicone-based solvent proposed in Patent Documents 5 and 6 is mainly dimethyl silicone. Dimethyl silicone has a high affinity for inkjet nozzle heads. The ink using this dimethyl silicone easily adheres to the nozzle head, and the ink adhering to the nozzle head may drip on the printed matter, or the ink may solidify near the nozzle head and cause nozzle non-ejection. is there.
The silicone-based solvents mentioned in Patent Documents 2 to 4 are also mainly dimethyl silicone, and have the same problems as those in Patent Documents 5 and 6. In particular, the lower the surface tension of dimethyl silicone, the more such a problem occurs.
Further, Patent Documents 2 to 6 do not disclose the problem that the dyed rake pigment is dyed in the oil-based ink, and do not disclose an example of a specific combination of the dyed rake pigment and the silicone oil. ..

In Patent Document 7, an insulating solvent having a siloxane bond in the molecular skeleton is used, and what kind of functional group is bonded to the siloxane bond of this solvent and the number of siloxane bonds are disclosed in detail. Absent. Therefore, the physical characteristics of this solvent and its action cannot be specified. Further, Patent Document 7 does not disclose a dyed rake pigment.

An object of the present invention is to provide an oil-based inkjet ink that prevents dyeing of a dyed rake pigment contained in an ink, prevents the ink from adhering to a nozzle plate, and has excellent drying properties of printed matter. ..

One embodiment is an oil-based inkjet ink containing a dyed lake pigment, a pigment dispersant, and a non-aqueous solvent, wherein the non-aqueous solvent contains a silicone oil having a surface tension of 20 mN / m or more and 28 mN / m or less. is there.

According to one embodiment, it is possible to provide an oil-based inkjet ink that prevents dyeing of the dyed lake pigment contained in the ink, prevents the ink from adhering to the nozzle plate, and has excellent drying property of the printed matter.

Hereinafter, the present invention will be described using one embodiment. The illustrations in the following embodiments do not limit the invention.
The oil-based inkjet ink according to one embodiment (hereinafter, may be simply referred to as ink) includes a dyed lake pigment, a pigment dispersant, and a non-aqueous solvent, and the non-aqueous solvent has a surface tension of 20 mN / m or more. It is characterized by containing a silicone oil having a temperature of 28 mN / m or less.
According to this, it is possible to prevent the dyeing of the dyed rake pigment contained in the ink, prevent the ink from adhering to the nozzle plate, and provide an oil-based inkjet ink having excellent drying property of the printed matter.

This ink can enhance the light resistance of the printed image by preventing the dyeing of the dyed rake pigment, and can prevent the phenomenon of the printed image bleeding from the printed area to the unprinted area. When the dyed lake pigment is dyed, when the ink is applied to the recording medium, the dyed component may permeate into the recording medium and bleed from the printed area to the unprinted area. Further, the dyed component may enter the fiber of the recording medium and be dyed with a color brighter than that of the pigment itself to color the boundary between the printed area and the unprinted area.
Further, by using silicone oil having a surface tension of 20 mN / m or more and 28 mN / m or less as a non-aqueous solvent, the wettability of the ink to the nozzle plate is lowered, the adhesion of the ink to the nozzle plate is prevented, and the printed matter is printed. The drying speed of the ink can be increased.

The ink contains a dyed lake pigment.
The dyed lake pigment is a pigment in which a water-soluble dye is insolubilized and fixed to an extender pigment.
As the dyed rake pigment, a basic dyed rake pigment, an acidic dyed rake pigment, or the like can be used.
The dyed lake pigment has good dispersibility and can further improve the storage stability of the ink. Further, since the dyed lake pigment has good dispersibility, it is possible to prevent the pigment from agglutinating, and it is possible to further prevent the ink from adhering to the nozzle plate. Further, since the dyed lake pigment has good dispersibility, when the ink is applied to the recording medium, the dyeing rake pigment has good releasability from the solvent, and the drying property of the printed matter can be further improved. The basic dyed lake pigment has more excellent dispersibility and can be preferably used.

The basic dyeing lake pigment is a pigment in which a dye having a basic group such as an amino group is insolubilized with a precipitant and fixed to an extender pigment. Phosphor-tungstic acid, silico-molybdic acid, silico-tungstic acid, tannic acid, lauric acid, gallic acid, ferricyanide and ferrocyanide, synthetic mediators (Qatar, Tamor) and the like can be used.
Examples of the basic dyeing lake pigment include xanthene dyes (Rhodamine 6G, Rhodamine, etc.), triphenylmethane dyes (methyl violet, malachite green, etc.), triphenylmethane thiazole dyes, thiazole dyes, diphenylmethane dyes. , Azomethine dyes and the like can be raked and fixed to the extender pigment.

Acid-dyed lake pigments are pigments in which dyes having acidic groups such as sulfo groups and carboxy groups are insolubilized with a precipitant and fixed to extender pigments, and the precipitants include calcium, barium, aluminum and sodium. Etc., such as metal salts can be used.
Examples of acidic dyed rake pigments include persian orange dyes, nitroso dyes, monoazo dyes, quinoline dyes, acidic xanthene dyes, anthracinone dyes (alizarin, madder, etc.), indigoid dyes, and the like. A pigment fixed to the extender pigment can be used.

The dyed lake pigment is, for example, C.I. I. Pigment Yellow 18, C.I. I. Pigment Yellow 100, C.I. I. Pigment Yellow 104, C.I. I. Pigment Yellow 115, C.I. I. Pigment Yellow 117; C.I. I. Pigment Orange 17: 1 (Persian Orange Lake), C.I. I. Pigment Orange 39; C.I. I. Pigment Red 63 (Indigo Carmine Lake), C.I. I. Pigment Red 81, C.I. I. Pigment Red 81: 1, C.I. I. Pigment Red 81: 2, C.I. I. Pigment Red 81: 3, C.I. I. Pigment Red 81: 4, C.I. I. Pigment Red 82, C.I. I. Pigment Red 83, C.I. I. Pigment Red 84, C.I. I. Pigment Red 90, C.I. I. Pigment Red 90: 1, C.I. I. Pigment Red 151, C.I. I. Pigment Red 169, C.I. I. Pigment Red 172, C.I. I. Pigment Red 173, C.I. I. Pigment Red 174, C.I. I. Pigment Red 191 and C.I. I. Pigment Red 193; C.I. I. Pigment Vioret 1, C.I. I. Pigment Vioret 2, C.I. I. Pigment Vioret 2: 2, C.I. I. Pigment Vioret 3, C.I. I. Pigment Vioret 3: 1, C.I. I. Pigment Vioret 3: 3, C.I. I. Pigment Vioret 4, C.I. I. Pigment Vioret 5, C.I. I. Pigment Vioret 5: 1, C.I. I. Pigment Vioret 6: 1, C.I. I. Pigment Vioret 7: 1, C.I. I. Pigment Vioret 9, C.I. I. Pigment Vioret 12, C.I. I. Pigment Vioret 20, C.I. I. Pigment Vioret 26, C.I. I. Pigment Vioret 27, C.I. I. Pigment Vioret 39, C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 1: 2, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 8, C.I. I. Pigment Blue 9, C.I. I. Pigment Blue 10, C.I. I. Pigment Blue 11, C.I. I. Pigment Blue 12, C.I. I. Pigment Blue 14, C.I. I. Pigment Blue 53 (Brilliant Blue Lake), C.I. I. Pigment Blue 53, C.I. I. Pigment Blue 62, C.I. I. Pigment Blue 63; C.I. I. Pigment Green 1, C.I. I. Pigment Green 2, C.I. I. Pigment Green 3, C.I. I. Pigment Green 4, C.I. I. Pigment Green 8, C.I. I. Pigment Green 9, C.I. I. Pigment Green 10, C.I. I. Pigment Green 12, C.I. I. Pigment Green 45; C.I. I. Pigment Brown 3 and the like.
These can be used alone or in combination of two or more.

Among them, a xanthene-based basic dyeing rake pigment obtained by rakeing a xanthene-based dye and a triphenylmethane-based basic dyeing rake pigment obtained by raked a triphenylmethane-based dye can be preferably used, and xanthene-based basic dyeing can be used. Lake pigments are more preferred.

The xanthene-based basic dyeing lake pigment is a pigment in which a xanthene-based dye is raked and fixed to an extender pigment. The xanthene dye is a dye having a xanthene skeleton represented by the following structural formula, and examples thereof include rhodamine dyes, fluorescein dyes, and eosin dyes. From the viewpoint of color tone, rhodamine dyes such as rhodamine, rhodamine B, and rhodamine 6G are preferable.

Examples of the xanthene-based basic dyeing lake pigment include C.I. I. Pigment RED 81 (Rhodamine 6G (PTMA)), C.I. I. Pigment RED 81: 1 (Rhodamine 6G (STMA)), C.I. I. Pigment RED 81: 2 (Rhodamine (SMA)), C.I. I. Pigment RED 81: 3 (Rhodamine (PMA)), C.I. I. Pigment RED 81: 4 (Rhodamine (PTMA) and Rhodamine 6G (tannic acid)), C.I. I. Pigment RED 169 (Rhodamine 6G (CFA)) and the like can be preferably used.
Among them, C.I. I. Pigment RED 81, C.I. I. Pigment RED 81: 4, C.I. I. Pigment RED 169 can be preferably used.
These may be used alone or in combination of two or more.

The ink may contain other pigments as long as the effects of the present invention are not impaired.
For example, from the viewpoint of the density and saturation of the printed image, an azo lake pigment can be used together with the xanthene dyed lake pigment.
The azo lake pigment that can be used in combination is preferably a soluble azo pigment, for example, C.I. I. Pigment RED 48: 1, C.I. I. Pigment RED 48: 2, C.I. I. Pigment RED 48: 3, C.I. I. Pigment RED 48: 4, C.I. I. Pigment RED 48: 5, C.I. I. Pigment RED 49, C.I. I. Pigment RED 49: 1, C.I. I. Pigment RED 49: 2, C.I. I. Pigment RED 49: 3, C.I. I. Pigment RED 52: 1, C.I. I. Pigment RED 52: 2, C.I. I. Pigment RED 53: 1, C.I. I. Pigment RED 54, C.I. I. Pigment RED 57: 1, C.I. I. Pigment RED 58, C.I. I. Pigment RED 58: 1, C.I. I. Pigment RED 58: 2, C.I. I. Pigment RED 58: 3, C.I. I. Pigment RED 58: 4, C.I. I. Pigment RED 60: 1, C.I. I. Pigment RED 63, C.I. I. Pigment RED 63: 1, C.I. I. Pigment RED 63: 2, C.I. I. Pigment RED 63: 3, C.I. I. Pigment RED 64: 1, C.I. I. Pigment RED 68, C.I. I. Pigment RED 200, C.I. I. Pigment RED 237, C.I. I. Pigment RED 239, and C.I. I. Pigment RED 247 and the like can be mentioned.
The mass ratio of the xanthene-based dyed lake pigment to the azolake-based pigment is preferably from 10:00 to 3: 7, and more preferably from 10:00 to 5: 5.

The dispersion form of the pigment may be a so-called capsule pigment in which the pigment is coated with a non-oil-soluble resin or a dispersion in which colored resin particles are dispersed with a pigment dispersant, but the pigment dispersant is directly adsorbed on the pigment surface. It is preferably a dispersed dispersion.

The average particle size of the pigment is preferably 300 nm or less, more preferably 200 nm or less, still more preferably 150 nm or less, from the viewpoint of discharge stability and storage stability.
The pigment is usually 0.01 to 20% by mass with respect to the total amount of ink, preferably 1% by mass or more, more preferably 5% by mass or more from the viewpoint of printing density, and 15% by mass or less from the viewpoint of ink viscosity. preferable.

In order to stably disperse the pigment in the ink, a pigment dispersant can be used together with the pigment.
Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high-molecular-weight acid ester, a salt of a high-molecular-weight polycarboxylic acid, a salt of a long-chain polyaminoamide and a polar acid ester, and a high-molecular-weight unsaturated acid. Esters, copolymers of vinylpyrrolidone and long-chain alkene, modified polyurethanes, modified polyacrylates, polyether ester-type anionic activators, polyoxyethylene alkyl phosphates, polyester polyamines and the like are preferably used.

Examples of commercially available pigment dispersants include "Antalon V216 (vinylpyrrolidone / hexadecene copolymer)" and V220 (vinylpyrrolidone / eicosen copolymer) "manufactured by ISP Japan Co., Ltd. (both are commercial products. Name); "Solsperse 13940 (polyester amine type), 16000, 17000, 18000 (fatty acid amine type), 11200, 24000, 28000" (all trade names); "Fuka 400" manufactured by BASF Japan Co., Ltd. , 401, 402, 403, 450, 451, 453 (modified copolymer), 46, 47, 48, 49, 4010, 4055 (modified polyurethane) "(all trade names);" Disparon KS- "manufactured by Kusumoto Kasei Co., Ltd. 860, KS-873N4 (polyester amine salt) "(all trade names);" Discol 202, 206, OA-202, OA-600 (multi-chain polymer nonionic) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. "(All product names);" DISPERBYK2155, 9077 "manufactured by Big Chemie Japan Co., Ltd. (all product names);" Hypermer KD2, KD3, KD11, KD12 "(all product names) manufactured by Crowder Japan Co., Ltd. ..

The pigment dispersant may be appropriately set as long as the amount of the pigment can be sufficiently dispersed in the ink. For example, in terms of mass ratio, the pigment dispersant can be blended in an amount of 0.1 to 5 with respect to the pigment 1, preferably 0.1 to 1. The pigment dispersant can be blended in an amount of 0.01 to 15% by mass, preferably 0.01 to 10% by mass, based on the total amount of the ink.
The resin component containing the pigment dispersant can be blended in the oil-based ink in an amount of 15% by mass or less, more preferably 10% by mass or less, based on the total amount of the ink. As a result, it is possible to prevent an increase in ink viscosity and further improve the ejection performance.

The ink can contain silicone oil having a surface tension of 20 mN / m or more and 28 mN / m or less.
The surface tension of the silicone oil is preferably 20 mN / m or more, more preferably 22 mN / m or more. As a result, the wettability of the ink to the nozzle plate can be lowered, and the ink can be prevented from adhering to the nozzle plate.
The surface tension of the silicone oil is preferably 28 mN / m or less, more preferably 26 mN / m or less. As a result, the ink quickly penetrates into the recording medium, and the drying speed of the printed matter can be increased.

Here, the surface tension can be obtained according to the bubble pressure method (maximum bubble pressure method). For example, the surface tension can be measured using "SITA Mechanism GmbH Science line t60" manufactured by SITA Process Solutions.

The surface tension of the entire ink is not limited to this, but is preferably 20 mN / m or more, and more preferably 22 mN / m or more. The surface tension of the entire ink is preferably 30 mN / m or less, more preferably 27 mN / m or less.

The silicone oil is not particularly limited as long as the surface tension is 20 mN / m or more and 28 mN / m or less, and a liquid compound can be used at 23 ° C. with silicon atoms and carbon atoms in one molecule.
As the silicone oil, a compound having a silyl group, a compound having a silyloxy group, a compound having a siloxane bond and the like can be used, and a polysiloxane compound can be particularly preferably used.

As the silicone oil, for example, chain silicone oil, cyclic silicone oil, modified silicone oil and the like can be used.
The chain silicone oil may have a straight chain or a branched chain, and the number of silicon is preferably 15 to 30, more preferably 17 to 25. Examples of the chain silicone oil include dotriacontanemethylpentadecasiloxane and hexatriacontanemethylheptadecasiloxane.
The cyclic silicone oil is preferably a cyclic polysiloxane having 5 to 9 silicon numbers, and is a cyclic such as decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, hexadecamethylcyclooctasiloxane, and octadecamethylcyclononasiloxane. Polydimethylsiloxane can be preferably used.

As the modified silicone oil, a silicone oil in which various organic groups are introduced into some silicon atoms of the chain or cyclic dimethyl silicone oil can be used. As the modified silicone oil, it is preferable that all silicon atoms are bonded only to either carbon atoms or siloxane-bonded oxygen atoms. The modified silicone oil is preferably a non-reactive silicone oil. The modified silicone oil preferably has only silicon atoms, carbon atoms, oxygen atoms, and hydrogen atoms as constituent atoms.

The modified silicone oil includes, for example, a group consisting of at least one methyl group contained in a chain or cyclic dimethyl silicone oil consisting of an alkyl group, a carboxylic acid ester bond-containing group, an aromatic ring-containing group, and an ether bond-containing group. Compounds substituted by one or more selected may be used.
Further, as the modified silicone oil, for example, a silicon atom of another chain or cyclic dimethyl silicone oil is bonded to at least one silicon atom contained in the chain or cyclic dimethyl silicone oil via an alkylene group. Compounds can be used. In this case, at least one methyl group contained in the chain or cyclic dimethyl silicone oil bonded via the alkylene group comprises an alkyl group, a carboxylic acid ester bond-containing group, an aromatic ring-containing group, and an ether bond-containing group. It may be replaced by one or more selected from the group.

Examples of the modified silicone oil include alkyl-modified silicone oil, aryl-modified silicone oil such as phenyl-modified silicone oil and aralkyl-modified silicone oil, carboxylic acid ester-modified silicone oil, alkylene-modified silicone oil, and polyether-modified silicone oil. ..
The modified silicone oil preferably has a silicon number of 2 to 20, more preferably 2 to 10, further preferably 2 to 6, and even more preferably 3 to 6.

An example of a modified silicone oil has an organic group in which the number of silicon in one molecule is 2 to 6, the carbon atom is directly bonded to the silicon atom, and the total number of carbon and oxygen is 5 or more. A silicone oil having a total carbon number and oxygen number of 5 to 20 contained in an organic group having a total carbon number and oxygen number of 5 or more in a molecule is included. Hereinafter, this silicone oil is also referred to as modified silicone oil S.

The modified silicone oil S can have one or more selected from the group consisting of the following (A) to (D) as an organic group having a total of 5 or more carbon atoms and oxygen numbers.
(A) An alkyl group having 7 or more carbon atoms.
(B) A carboxylic acid ester bond-containing group having a total of 5 or more carbon atoms and oxygen numbers.
(C) An aromatic ring-containing group having 6 or more carbon atoms.
(D) An alkylene group having 7 or more carbon atoms.

From the viewpoint of preventing ink from adhering to the nozzle plate, the modified silicone oil S has a total of 5 to 5 carbons and oxygens contained in an organic group having a total of 5 or more carbons and oxygens in one molecule. It is preferably 12.
Further, the modified silicone oil S is the total number of carbons and oxygens contained in the organic group having a total number of carbons and oxygens in one molecule of 5 or more from the viewpoint of lowering the viscosity of the ink and improving the ejection performance. Is preferably 8 to 20.
When one molecule of the modified silicone oil S contains two or more organic groups having a total of 5 or more carbon atoms and oxygen numbers, an organic group having a total of 5 or more carbon atoms and oxygen numbers in one molecule. The total number of carbon atoms and oxygen number of 2 or more is the total number of carbon atoms and oxygen number of organic groups having a total number of 2 or more carbon atoms and oxygen number of 5 or more.

An example of the modified silicone oil S includes silicone oil, which is a compound represented by the following general formula (X).

In the general formula (X), R ¹ is a divalent organic group in which a carbon bond is directly bonded to an oxygen atom or a silicon atom, and R ² is an independent carbon bond directly bonded to a silicon atom. It is a monovalent organic group, m and n are independently integers of 0 to 4, p are independently integers of 0 to 2, and the number of silicon in one molecule is 2. ~ 6, and ^{at least one of R 1} and R ² is an organic group having a total of 5 or more carbon atoms and oxygen numbers, and has a total of 5 or more carbon atoms and oxygen numbers in one molecule. The total number of oxygen and carbon contained in the organic group is 5 to 20.

In the general formula (X), R ¹ is an oxygen atom or a divalent organic group having a total of 5 or more carbon atoms and oxygen numbers, and R ² is independently a methyl group or a carbon number of carbon atoms. And a monovalent organic group having a total oxygen number of 5 or more is preferable.

Preferably, in the general formula (X), R ¹ is an oxygen atom or an alkylene group having 7 or more carbon atoms, and R ² is an independent methyl group, an alkyl group having 7 or more carbon atoms, and a carbon number of carbons, respectively. A carboxylic acid ester bond-containing group having a total oxygen number of 5 or more, or an aromatic ring-containing group having 6 or more carbon atoms, and ^{at least one of R 1} and R ² is an alkylene group having 7 or more carbon atoms. Selected from the group consisting of an alkyl group having 7 or more carbon atoms, a carboxylic acid ester bond-containing group having a total of 5 or more carbon atoms and an oxygen number, and an aromatic ring-containing group having 6 or more carbon atoms, the number of carbon atoms in one molecule. The number of oxygen and carbon contained in an alkylene group having 7 or more, an alkyl group having 7 or more carbon atoms, a carboxylic acid ester bond-containing group having a total of 5 or more carbon atoms and an oxygen number, and an aromatic ring-containing group having 6 or more carbon atoms. The total number is 5-20.

Other examples of the modified silicone oil S include silicone oil, which is a compound represented by the following general formula (X-1).

In the general formula (X-1), R ² is a monovalent organic group in which a carbon atom is directly bonded to a silicon atom independently, n is an integer of 0 to 4, and p is each. Independently, it is 0 or 1, the number of silicon in one molecule is 2 to 6, and ^{at least one of R 2} is an organic group having a total of 5 or more carbon and oxygen, and 1 The total number of carbon atoms and the number of carbon atoms in the molecule is 5 or more. The total number of oxygen numbers and the number of carbon atoms contained in the organic group is 5 to 20.

In the general formula (X-1), R ² is preferably a methyl group or a monovalent organic group having a total of 5 or more carbon atoms and oxygen numbers, respectively.
In the general formula (X-1), ^{at least one of R 2} is an alkyl group having 7 or more carbon atoms, a carboxylic acid ester bond-containing group having a total of 5 or more carbon atoms and oxygen number, and a carbon number of carbon atoms. It is preferable that the number is 1 or more selected from the group consisting of aromatic ring-containing groups having a value of 6 or more.

In the modified silicone oil S, the alkyl group having 7 or more carbon atoms may have a straight chain or a branched chain, and may be a chain or an alicyclic.
The number of carbon atoms of this alkyl group is preferably 7 or more, more preferably 8 or more, and further preferably 10 or more.
The number of carbon atoms of this alkyl group is preferably 20 or less, more preferably 16 or less, still more preferably 12 or less.

Examples of the alkyl group having 7 or more carbon atoms include a heptyl group, an octyl group, an isooctyl group, a nonyl group, a decyl group, a dodecyl group, a hexadecyl group and an eicosyl group.
It is preferably an octyl group, a decyl group, a dodecyl group or a hexadecyl group, and more preferably a decyl group or a dodecyl group.

As the modified silicone oil S having an alkyl group, for example, a compound represented by the following general formula (1) can be used.

In the general formula (1), R is an alkyl group having a straight chain or a branched chain having 7 to 20 carbon atoms, and m and n are independently integers of 0 to 2 and m + n ≦ 2. ..

In the general formula (1), R is an alkyl group having a straight chain or a branched chain having 7 to 20 carbon atoms. When the alkyl group represented by R has 7 or more carbon atoms, more preferably 8 or more carbon atoms, and further preferably 10 or more carbon atoms, the wettability of the ink to the nozzle plate can be improved. In particular, when the value is 10 or more, the surface tension increases and the wettability is improved.
Further, when the number of carbon atoms of the alkyl group represented by R is 20 or less, more preferably 16 or less, still more preferably 12 or less, it is possible to suppress the increase in viscosity of the ink and improve the ejection performance.

In the modified silicone oil S, the carboxylic acid ester bond-containing group is represented by ^{-R Bb-} O- (CO) -R ^Ba in which the carboxylic acid ester bond is bonded to the silicon atom of the siloxane bond in the main chain via the alkylene group. Or ^{a group represented by -R Bb-} (CO) -OR ^Ba can be preferably used.
Here, R ^Ba may have a linear or branched chain having one or more carbon atoms, and is preferably a chain or alicyclic alkyl group. Further, R ^Bb may have a linear or branched chain having 1 or more carbon atoms, and is preferably a chain or alicyclic alkylene group. The alkylene group that connects the silicon atom of the siloxane bond in the main chain and the carboxylic acid ester bond is more preferably having 2 or more carbon atoms.
The total number of carbon atoms and oxygen number of the carboxylic acid ester bond-containing group is the number of carbon atoms of one carbon atom and two oxygen atoms of the ester bond (-O- (CO)-) and the number of carbon atoms of the alkyl group (R ^Ba ). And the number of carbon atoms of the alkylene group ( ^RBb).

In the carboxylic acid ester bond-containing group, the alkyl group (R ^Ba ) is, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group and a heptyl group. Examples thereof include a group, an octyl group, an isooctyl group, a nonyl group, a decyl group, a dodecyl group, a hexadecyl group, a heptadecyl group and the like.
A pentyl group, a heptyl group, a nonyl group and a tridecylic group are preferable, and a heptyl group and a nonyl group are more preferable.

In the carboxylic acid ester bond-containing group, the alkylene group ( ^RBb ) is preferably a linear alkylene group having 1 to 8 carbon atoms, for example, a methylene group, an ethylene group, a propylene group, a trimethylene group, n-butylene, and the like. Examples thereof include an isobutylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, an isooctylene group and the like.
It is preferably an ethylene group.

In the modified silicone oil S having a carboxylic acid ester bond-containing group, in the above general formula (X-1), R ² independently has a carbon atom directly bonded to a methyl group or a silicon atom and has a carbon number of carbon atoms. And a carboxylic acid ester bond-containing group having a total oxygen number of 5 or more, n is an integer of 0 to 4, p is independently 0 or 1, and the number of silicon in one molecule. 2 to 6, and ^{at least one of R 2} is the carboxylic acid ester bond-containing group, and the total number of oxygen and carbon contained in the carboxylic acid ester bond-containing group in one molecule is 5 to 5. A compound of 20 can be preferably used.

An example of the modified silicone oil S having a carboxylic acid ester bond-containing group includes a compound represented by the following general formula (B1).

In the general formula (B1), ^RB1 is a carboxylic acid ester bond-containing group in which a carbon atom is directly bonded to a methyl group or a silicon atom and the total number of carbon atoms and oxygen number is 5 or more. , ^RB2 are carboxylic acid ester bond-containing groups in which a carbon atom is directly bonded to a methyl group, a trimethylsilyloxy group, or a silicon atom, and the total number of carbon atoms and oxygen number is 5 or more, respectively. ^At least one of B1 and ^RB2 is a carboxylic acid ester bond-containing group having a total of 5 or more carbon atoms and oxygen numbers, n is an integer of 0 to 4, and the number of silicon in one molecule is 2 to 6
The carboxylic acid ester bond-containing group is as described above.

In modified silicone oil S, the aromatic ring-containing group is a group the aromatic ring to the silicon atom of the siloxane bond in the main chain is represented by a direct bond to -R ^Ca, or an alkylene group to the silicon atom of the siloxane bond in the main chain ^{A group represented by -RCb-} R ^{Ca to} which an aromatic ring is bonded can be preferably used.
Here, R ^Ca is preferably an aromatic ring having 6 or more carbon atoms. Further, ^RCb may have a linear or branched chain having 1 or more carbon atoms, and is preferably a chain or alicyclic alkylene group.
Aromatic ring-containing group, if the aromatic ring to the silicon atom of the siloxane bond in the main chain is a group represented by direct binding to -R ^Ca, as branched side chain, such as trimethylsilyloxy group from the siloxane bond in the main chain It is preferable that it is branched. The aromatic ring-containing group is more preferably a group represented by ^-RCb- R ^{Ca in} which an aromatic ring is bonded to a silicon atom of a siloxane bond in the main chain via an alkylene group.
The carbon number of the aromatic ring-containing group is the sum of ^{the carbon number of the aromatic ring (RCa} ) and the carbon number of any alkylene group ( ^RCb).

In the aromatic ring-containing group, the aromatic ring moiety ( ^RCa ) contains, for example, a phenyl group, a tolyl group, a xsilyl group, a trimethylphenyl group, a biphenyl group, a naphthyl group, an anthracenyl group, or at least one hydrogen atom thereof. A functional group substituted with an alkyl group can be mentioned.

In the aromatic ring-containing group, any alkylene group ( ^RCb ) is preferably an alkylene group which may have a linear or branched chain having 1 to 8 carbon atoms, for example, a methylene group, an ethylene group, or a propylene. Examples thereof include a group, a trimethylene group, an n-butylene group, an isobutylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, an isooctylene group and the like.
Preferably, it is a propylene group, a methylethylene group, or an ethylene group.

In the modified silicone oil S having an aromatic ring-containing group, in the above general formula (X-1), R ² independently has a carbon atom directly bonded to a methyl group or a silicon atom and has 6 carbon atoms. The above aromatic ring bond-containing group, n is an integer of 0 to 4, p is independently 0 or 1, and the number of silicon in one molecule is 2 to 6, and R ^At least one of the two is the aromatic ring bond-containing group, and a compound having a total number of carbon atoms contained in the aromatic ring bond-containing group in one molecule of 6 to 20 can be preferably used.

An example of the modified silicone oil S having an aromatic ring-containing group includes a compound represented by the following general formula (C1).

In the general formula (C1), ^RC1 is an aromatic ring-containing group in which a carbon atom is directly bonded to a methyl group or a silicon atom and has 6 or more carbon atoms, and ^RC2 is an independent group. In particular, it is an aromatic ring-containing group in which a carbon atom is directly bonded to a methyl group, a trimethylsilyloxy group, or a silicon atom and has 6 or more carbon atoms, and ^{at least one of RC1} and ^RC2 has the above carbon number. Is an aromatic ring-containing group having a value of 6 or more, n is an integer of 0 to 4, and the number of silicon in one molecule is 2 to 6.
The aromatic ring-containing group is as described above.
In the general formula (C1), it is preferable that the compound has n = 1 and has a trisiloxane skeleton.

Examples of the modified silicone oil S having an aromatic ring-containing group include diphenyldimethicone, trimethylsiloxyphenyldimethicone, and 1,1,1,5,5,5-hexamethyl-3-phenyl-3- (trimethylsilyloxy) tri. Methylphenyl silicone such as siloxane can be used.

One embodiment of the modified silicone oil S is a compound having 2 to 6 silicon atoms and an alkylene group having 7 or more carbon atoms, preferably carbons at both ends of the alkylene group having 7 or more carbon atoms. A compound in which a silyl group or at least one siloxane bond is bonded to each atom.

Examples of the alkylene group having 7 or more carbon atoms include a heptylene group, an octylene group, an isooctylene group, a nonylene group, a decylene group, a dodecylene group, a hexadecylene group, and an ecosilene group.
It is preferably an octylene group, a decylene group, or a dodecylene group, and more preferably an octylene group or a decylene group.

In the modified silicone S having an alkylene group, in the above general formula (X), R ¹ is an alkylene group having 7 or more carbon atoms, R ² is a methyl group, and m and n are independent of each other. Therefore, a compound which is an integer of 0 to 4, p is an integer of 0 to 2 independently, and the number of silicon in one molecule is 2 to 6 can be preferably used.

The modified silicone oil S described above is not limited to this, and can be produced by the following method.
For example, a modified silicone oil S can be obtained by reacting a siloxane raw material with a reactive compound having a reactive group together with an organic group having a total of 5 or more carbon atoms and oxygen numbers in an organic solvent. .. The siloxane raw material and the reactive compound are preferably reacted with the reactive group of the siloxane raw material and the reactive group of the reactive compound in a molar ratio of 1: 1 to 1: 1.5. Further, in the reaction, a catalyst such as a zero-valent platinum olefin complex, a zero-valent platinum vinyl siloxane complex, a divalent platinum olefin complex halide, or a platinum catalyst such as chloroplatinic acid can be preferably used.

Examples of the siloxane raw material include 1,1,1,3,5,5,5-heptamethyltrisiloxane, 1,1,1,3,3,5,7,7,7-nonamethyltetrasiloxane, 1 , 1,1,3,3,5,7,7,9,9,9-Undecamethylpentasiloxane, pentamethyldisiloxane, 1,1,3,3,5,5,5-heptamethyltrisiloxane , 1,1,3,3-tetramethyldisiloxane, 1,1,3,3,5,5-hexamethyltrisiloxane, 1,1,3,3,5,5,7,7-octamethyltetra Siloxane, 1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, 1,1, 1,5,5,5-hexamethyl-3- (trimethylsilyloxy) trisiloxane, 1,1,1,5,5,5-hexamethyltrisiloxane, 1,1,1,3,5,7,7, 7-Octamethyltetrasiloxane, 1,1,3,5,5-pentamethyl-3- (dimethylsilyloxy) trisiloxane, 1,1,3,3,5,5,7,7,9,9,11 , 11-Dodecamethylhexasiloxane, 1,1,1,5,5,5-hexamethyl-3- (trimethylsilyloxy) trisiloxane and the like can be used.

The reactive compound preferably has a carbon double bond as a reactive group.
In order to introduce an alkyl group into the modified silicone oil S, the reactive compounds include 1-heptene, 1-octene, 2-octene, 1-nonene, 1-decene, 1-dodecene, 1-hexadecene and 1-eicosene. Alkenes and the like having 7 or more carbon atoms can be used.
In addition to the alkene, an alicyclic hydrocarbon group having an ethylenically unsaturated double bond such as vinylcyclohexane can be used.

In order to introduce an ester bond-containing group into the modified silicone oil S, as reactive compounds, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutate, vinyl pentanate, vinyl pivalate, vinyl hexanoate, vinyl heptate are used. , 2-ethylhexanoate, vinyl octanoate, vinyl isooctanoate, vinyl nonanoate, vinyl decanoate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl eicoate, allyl hexanoate, etc. A fatty acid vinyl or a fatty acid allyl compound having a total of 6 or more can be used.

In order to introduce an aromatic ring-containing group into the modified silicone oil S, styrene, 4-methylstyrene, 2-methylstyrene, 4-tert-butylstyrene, allylbenzene, 1-allylnaphthalene, 4-allylnaphthalene and 4-allylnaphthalene are used as reactive compounds. Phenyl-1-butene, 2,4-diphenyl-4-methyl-1-pentene, 1-vinylnaphthalene, α-methylstyrene, 2-methyl-1-phenylpropene, 1,1-diphenylethylene, triphenylethylene, Use an allyl compound having a vinyl bond such as 2,4,6-trimethylstyrene, cis-β-methylstyrene, trans-β-methylstyrene, 3-phenyl-1-propene and an aromatic ring having 6 or more carbon atoms. be able to.

In order to introduce an alkylene group into the modified silicone oil S, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,11-dodecadiene, 1 and 1 are used as reactive compounds. , 10-Undecadiene, 1,13-Tetradecadiene, Hexadecadiene, Eikosaziene and other diene compounds having 7 or more carbon atoms can be used.

Examples of the silicone oil include "KF-96L-10CS" and "KF-56A" manufactured by Shinetsu Chemical Industry Co., Ltd .; "DC345 Fluid" and "FZ-3196" manufactured by Toray Dow Corning Co., Ltd .; manufactured by Tokyo Kasei Kogyo Co., Ltd. Commercially available products such as "1,1,1,5,5,5-hexamethyl-3-phenyl-3- (trimethylsilyloxy) trisiloxane", "decamethylcyclopentasiloxane", and "dodecamethylcyclohexasiloxane" are used. You may.

The silicone oil is preferably contained in an amount of 15% by mass or more based on the total amount of the non-aqueous solvent. This makes it possible to improve the drying property of the printed matter while preventing the dyeing of the dyed rake pigment. More preferably, the silicone oil is contained in an amount of 30% by mass or more, particularly 50% by mass or more, still more preferably 70% by mass or more, based on the total amount of the non-aqueous solvent.
Silicone oil is contained in an amount of 100% by mass or less based on the total amount of the non-aqueous solvent. The silicone oil may be contained in an amount of 90% by mass or less based on the total amount of the non-aqueous solvent.
Since silicone oil has an affinity for the nozzle plate depending on the material of the nozzle plate, the wettability of the ink to the nozzle plate can be further improved by limiting the blending amount to some extent.
The blending amount of the silicone oil with respect to the total amount of the ink varies depending on the total amount of the non-aqueous solvent used, but may be contained in an amount of 12 to 98% by mass or 15 to 90% by mass.

The ink may contain other non-aqueous solvents.
As the other non-aqueous solvent, either a non-polar organic solvent or a polar organic solvent can be used. In the present embodiment, it is preferable to use a water-insoluble organic solvent that does not uniformly mix with the same volume of water at 1 atm and 20 ° C. as the non-aqueous solvent.

As the non-polar organic solvent, for example, petroleum-based hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents can be preferably mentioned.
Examples of the aliphatic hydrocarbon solvent and the alicyclic hydrocarbon solvent include non-aqueous solvents such as paraffin-based, isoparaffin-based, and naphthenic-based solvents. Commercially available products include No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent H, Cactus Normal Paraffin N-10, Cactus Normal Paraffin N-11, Cactus Normal Paraffin N-12, Cactus Normal Paraffin N-13, Cactus Normal. Paraffin N-14, Cactus Normal Paraffin N-15H, Cactus Normal Paraffin YHNP, Cactus Normal Paraffin SHNP, Isosol 300, Isosol 400, Teclean N-16, Teclean N-20, Teclean N-22, AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, AF Solvent No. 7, Naftesol 160, Naftesol 200, Naftesol 220 (all manufactured by JXTG Energy Co., Ltd.); Isopar G, Isopar H, Isopar L, Isopar M, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Exol D130 (all manufactured by Exxon Mobile); Moresco White P-40, Moresco White P-60, Moresco White P-70, Moresco White P-80, Moresco White P-100, Moresco White P-120, Moresco White P-150, Moresco White P-200, Moresco White P-260, Moresco White P-350P (all manufactured by MORESCO Co., Ltd.) and the like are preferably mentioned. be able to.
As the aromatic hydrocarbon solvent, Grade Alken L, Grade Alken 200P (all manufactured by JXTG Energy Co., Ltd.), Solbesso 100, Solbesso 150, Solbesso 200, Solbesso 200ND (all manufactured by Exxon Mobile Co., Ltd.) and the like can be preferably mentioned. it can.
The distillation initial distillation point of the petroleum-based hydrocarbon solvent is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and even more preferably 200 ° C. or higher. The distillation initial distillation point can be measured according to JIS K0066 "Distillation test method for chemical products".

As the polar organic solvent, a fatty acid ester solvent, a higher alcohol solvent, a higher fatty acid solvent and the like can be preferably mentioned.
By using a polar organic solvent together with the silicone oil, the wettability of the ink to the nozzle plate can be lowered, and the adhesion of the ink to the nozzle plate can be further prevented. Among them, a higher alcohol solvent having 6 or more carbon atoms in one molecule, preferably 12 to 20 carbon atoms, has high polarity and high surface tension, and can further reduce the wettability of the ink to the nozzle plate.
The higher alcohol solvent having 6 or more carbon atoms in one molecule may have a straight chain or a branched chain, and may be saturated or unsaturated. The higher alcohol solvent having 6 or more carbon atoms may be a monohydric, divalent, trivalent, or polyhydric alcohol, but is preferably a monohydric alcohol because of its low viscosity.
Examples of higher alcohol-based solvents having 6 or more carbon atoms include 1-hexanol, n-octanol, isooctyl alcohol, 1-decanol, dodecanol, isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, oleyl alcohol, and isoeico. Syl alcohol, decyltetradecanol and the like can be mentioned.

When silicone oil is contained in an amount of 50% by mass or more based on the total amount of the non-aqueous solvent, an alcohol solvent having 6 or more carbon atoms in one molecule is blended in the following proportion to improve the bleeding and light resistance of the printed image. , The wettability of the ink to the nozzle plate can be improved.
The alcohol-based solvent having 6 or more carbon atoms in one molecule is preferably 2% by mass or more, more preferably 5% by mass or more, based on the total amount of the non-aqueous solvent.
The alcohol-based solvent having 6 or more carbon atoms in one molecule is preferably 15% by mass or less, more preferably 10% by mass or less, based on the total amount of the non-aqueous solvent.

Other polar organic solvents include, for example, isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, hexyl palmitate, isooctyl palmitate, Isostearyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate, hexyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isostear Fatty acid ester-based solvent having 13 or more carbon atoms in one molecule such as isopropyl acid, 2-octyldecyl pivalate, methyl soybean oil, isobutyl soybean oil, methyl toll oil, isobutyl toll oil, etc.; preferably 16 to 30 fatty acid ester-based solvents; lauric acid. , Isomyristic acid, palmitic acid, isopalmitic acid, α-linolenic acid, linoleic acid, oleic acid, isostearic acid and the like, which have 12 or more carbon atoms in one molecule, preferably 14 to 20 higher fatty acid solvents and the like. Be done.
The boiling point of a polar organic solvent such as a fatty acid ester solvent, a higher alcohol solvent, or a higher fatty acid solvent is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 250 ° C. or higher. preferable. The non-aqueous solvent having a boiling point of 250 ° C. or higher also includes a non-aqueous solvent having a boiling point.

These non-aqueous solvents may be used alone or in combination of two or more as long as they form a single phase.

In addition to the above components, the ink may contain various additives as long as the effects of the present invention are not impaired. As the additive, a nozzle clogging inhibitor, an antioxidant, a conductivity adjuster, a viscosity adjuster, a surface tension adjuster, an oxygen absorber and the like can be appropriately added. These types are not particularly limited, and those used in the art can be used.

The ink can be produced by mixing each component including a pigment and a non-aqueous solvent. Preferably, each component can be collectively or divided, mixed and stirred to prepare an ink. Specifically, all the components can be collectively or divided and dispersed in a disperser such as a bead mill, and if desired, can be prepared by passing through a filter such as a membrane filter.

The appropriate range of the viscosity of the oil-based inkjet ink varies depending on the nozzle diameter of the ejection head of the inkjet recording system, the ejection environment, etc., but in general, it is preferably 5 to 30 mPa · s at 23 ° C., and 5 to 15 mPa · s. Is more preferable, and it is more preferable that it is about 10 mPa · s.

The printing method using the inkjet ink is not particularly limited, and any method such as a piezo method, an electrostatic method, or a thermal method may be used, but the piezo method is preferable. When an inkjet recording device is used, it is preferable to eject the ink according to the present embodiment from the inkjet head based on a digital signal so that the ejected ink droplets adhere to the recording medium.

In the present embodiment, the recording medium is not particularly limited, and a printing paper such as plain paper, coated paper, or special paper, a cloth, an inorganic sheet, a film, an OHP sheet, or the like is used as a base material and an adhesive layer is formed on the back surface. An adhesive sheet or the like provided with the above can be used. Among these, printing paper such as plain paper and coated paper can be preferably used from the viewpoint of ink permeability.

Here, the plain paper is a paper in which an ink receiving layer, a film layer, or the like is not formed on the ordinary paper. Examples of plain paper include high-quality paper, medium-quality paper, PPC paper, stencil paper, recycled paper, and the like. Plain paper is a paper in which ink easily permeates because paper fibers having a thickness of several μm to several tens of μm form voids of several tens to several hundreds of μm.

Further, as the coated paper, an inkjet coated paper such as matte paper, glossy paper, or semi-glossy paper, or so-called coated printing paper can be preferably used. Here, the coating printing paper is a printing paper that has been conventionally used for letterpress printing, offset printing, gravure printing, etc., and has an inorganic pigment such as clay or calcium carbonate on the surface of high-quality paper or medium-quality paper. , A printing paper provided with a coating layer using a paint containing a binder such as starch. Coated printing paper can be used for finely coated paper, high-quality lightweight coated paper, medium-quality lightweight coated paper, high-quality coated paper, medium-quality coated paper, art paper, cast-coated paper, etc., depending on the amount of paint applied and the coating method. being classified.

Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the following examples.
"Making ink"
Tables 1 to 3 show the ink formulations.
Pigments, pigment dispersants, and various solvents shown in each table are mixed according to the blending amount shown in each table, and the residence time is 15 minutes with the bead mill "Dynomill KDL-A" (manufactured by Simmal Enterprises Co., Ltd.). , The pigment was sufficiently dispersed. Subsequently, coarse particles were removed with a membrane filter to obtain ink.

Details of the non-aqueous solvents and pigments shown in each table are shown in Tables 4 and 5, respectively.
The surface tension of each solvent shown in Table 4 was determined under the measurement conditions of 23 ° C. and 0.05 Hz using "SITA Messagenik GmbH science line t60" manufactured by SITA Process Solutions.
The pigment dispersants shown in each table are as follows.
S18000: "Solsperse 18000" manufactured by Japan Lubrizol Co., Ltd., 100% by mass of active ingredient.
Disperbyk2155: "Disperbyk2155" manufactured by Big Chemie Japan Co., Ltd., 100% by mass of active ingredient.

(Manufacturing Example 1)
The method for synthesizing the carboxylic acid ester-modified silicone oil shown in each table will be described.
50 parts by mass of hexane, 1,1,1,3,5,5,5-heptamethyltrisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.) 10 parts by mass, vinyl n-octaneate (Tokyo Chemical Industry Co., Ltd.) in a four-necked flask (Manufactured by the company) 8.4 parts by mass was charged. 0.02 parts by mass of a platinum catalyst 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex (Sigma-Aldrich) was added thereto, and the mixture was stirred at room temperature for 2 to 3 hours. Then, hexane as a reaction solvent and unreacted raw materials were removed by vacuum distillation to obtain a carboxylic acid ester-modified silicone oil.

(Manufacturing Example 2)
The method for synthesizing the aryl-modified silicone oil shown in each table will be described.
50 parts by mass of hexane, 1,1,3,3,5,5-hexamethyltrisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), 10 parts by mass, 3-phenyl-1-propen (Tokyo Chemical Industry Co., Ltd.) in a four-necked flask (Manufactured by the company) 12.5 parts by mass was charged. 0.02 parts by mass of a platinum catalyst 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex (Sigma-Aldrich) was added thereto, and the mixture was stirred at room temperature for 2 to 3 hours. Then, the reaction solvent hexane and the unreacted raw material were removed by vacuum distillation to obtain the target compound aryl-modified silicone oil.

The structural formulas of the obtained carboxylic acid ester-modified silicone and aryl-modified silicone are shown below. In the following formula, Me represents a methyl group.

"Evaluation"
The inks of Examples and Comparative Examples were evaluated by the following methods. The results of these evaluations are shown in each table.

(Storage stability)
Each ink was placed in a closed container and left in an environment of 70 ° C. for 4 weeks. The ink viscosity "initial value of viscosity" before standing and the ink viscosity "viscosity after 4 weeks" after leaving were measured, and the viscosity change rate was calculated from the following formula. From the viscosity change rate, the storage stability was evaluated according to the following criteria.
The ink viscosity was the viscosity at 23 ° C., and was measured using "Rheometer MCR302" (cone angle 1 °, diameter 50 mm) manufactured by Anton Paar Japan K.K.
Viscosity change rate = [(viscosity after 4 weeks x 100) / (initial value of viscosity)] -100 (%)
A: The viscosity change rate is less than 5%.
B: The viscosity change rate is 5% or more and less than 10%.
C: The viscosity change rate is 10% or more.

(Wetability of ink to nozzle plate)
Put each ink in a 30 ml glass container, pinch one side of the nozzle plate (length 5 cm, width 5 mm) used for the inkjet printer "Orphis EX9050" (trade name: Riso Kagaku Corporation) with tweezers, and the other side. 2 cm from one side was immersed in the ink for 5 seconds. Then, the nozzle plate was quickly pulled up, and the time t until the ink film remaining on the nozzle plate became ink droplets was measured. The same operation was repeated 10 times using the same nozzle plate, and the time t was measured for each. The average value was calculated and used as the ink repellent time. From the ink repellent time, the wettability of the ink with respect to the nozzle plate was evaluated according to the following criteria.

S: The ink repellent time is less than 3 seconds.
A: The ink repellent time is 3 seconds or more and less than 5 seconds.
B: The ink repellent time is 5 seconds or more and less than 10 seconds.
C: The ink repellent time is 10 seconds or more.

(Drying speed)
Each ink is loaded into the line-type inkjet printer "Orphis EX9050" (manufactured by Riso Kagaku Corporation), and is solid on plain paper "Ideal Paper Thin Mouth" (manufactured by Riso Kagaku Corporation) at a printing speed of 150 ppm and a resolution of 300 dpi x 300 dpi. The image was printed.
The obtained printed matter was rubbed with a white cotton cloth 10 times in 10 seconds with a clock meter CM-1 (manufactured by ATLAS ELECTRIC DEYICES). Thirty seconds after printing, the first rubbing with a white cotton cloth was performed.
The rubbed white cotton cloth was measured with a colorimeter X-rite eXact (manufactured by Videojet X-Rite Co., Ltd.), and the color difference ΔE from the non-rubbed portion was determined. The smaller the color difference ΔE, the faster the ink dries and the better the image fixability.
A: ΔE is less than 3.
B: ΔE is 3 or more and less than 7.
C: ΔE is 7 or more.

(Bleeding)
Using each ink, a printed matter was prepared in the same manner as the above-mentioned drying speed.
The boundary between the printed area and the unprinted area on the printed surface of the printed matter was observed with a "portable digital microscope Vinity" manufactured by 3R Systems Co., Ltd., and the bleeding of the boundary was evaluated according to the following criteria. When the pigment contained in the ink is dyed, bleeding at the boundary of the printed surface is observed.
A: No bleeding was observed at the boundary of the printed surface.
B: Bleeding was observed at the boundary of the printed surface.
C: The boundary of the printed surface was significantly blurred.

(Light resistance)
Using each ink, a printed matter was prepared in the same manner as the above-mentioned drying speed.
The printed matter was set on the weather resistance tester "Weatherometer Ci4000" (manufactured by Atlas) and irradiated for 72 hours ^{at a wavelength of 300-400 nm and an illuminance of 36 W / m 2.} The fading before and after irradiation was visually observed and evaluated according to the following criteria.
A: There is almost no fading.
B: It can be seen that the color has faded.
C: It can be seen that the color has faded significantly.

As shown in each table, each evaluation result was good with the ink of each example. Further, in the ink of each example, the initial viscosity was in the range of 5 to 15 mPa · s, and the viscosity was appropriate.

In Examples 1 to 3, various silicone oils having a preferable surface tension were used, and the evaluation results were good. Through Examples 1 to 3, the higher the surface tension of the silicone oil, the lower the wettability of the ink with respect to the nozzle plate, and the poor ink ejection can be prevented. On the other hand, the lower the surface tension of the silicone oil, the printed matter. It can be seen that the drying speed is high and the fixability of the printed matter is excellent.
In Examples 4 to 7, the silicone oil and other non-aqueous solvents were used in combination, and the evaluation results were good. From Examples 6 and 7, the wettability of the ink to the nozzle plate could be further improved by using isoeicocil alcohol, which is a higher alcohol solvent, together with the silicone oil.

In Examples 8 to 12, various dyed rake pigments were used, and each evaluation result was good. In Example 12, an acidic dyed lake pigment is used, but by using it together with a silicone oil having a surface tension within a preferable range, the storage stability and the wettability of the ink to the nozzle plate can be sufficiently improved. It was.

In Comparative Example 1, the surface tension of dimethyl silicone, which is a non-aqueous solvent, is as low as 19.7 mN / m, the wettability of the ink with respect to the nozzle plate deteriorates, and the problem of poor ink ejection occurs.
In Comparative Examples 2 to 4, the surface tensions of the petroleum-based hydrocarbon solvent, isotridecyl isononanoate, and isoeicocil alcohol, which are non-aqueous solvents, are high, the drying speed of the printed matter is slow, and the problem of fixability occurs.
In Comparative Examples 3 and 4, a polar solvent was used as the non-aqueous solvent, and the bleeding and light resistance of the printed matter were lowered.
In Comparative Examples 5 and 6, the comparative pigments pyrazolone and quinacridone were used, respectively, and storage stability was not sufficiently obtained. In Comparative Examples 5 and 6, the dispersibility of the pigment was poor, the wettability of the ink with respect to the nozzle plate was deteriorated, and the drying speed of the printed matter was also slowed down.

Claims (9)

An oil-based inkjet ink containing a dyeing lake pigment, a pigment dispersant, and a non-aqueous solvent, wherein the non-aqueous solvent contains a silicone oil having a surface tension of 20 mN / m or more and 28 mN / m or less. The oil-based inkjet ink according to claim 1, wherein the surface tension of the silicone oil is 22 mN / m or more and 26 mN / m or less. According to claim 1 or 2, the silicone oil is contained in an amount of 50% by mass or more based on the total amount of the non-aqueous solvent, and an alcohol solvent having 6 or more carbon atoms is further contained in an amount of 2% by mass or more and 15% by mass or less based on the total amount of the non-aqueous solvent. The oil-based inkjet ink described. The oil-based inkjet ink according to any one of claims 1 to 3, wherein the dyed rake pigment is a basic dyed rake pigment. The oil-based inkjet ink according to claim 4, wherein the dyed lake pigment is a xanthene-based basic dyed lake pigment. The dyed rake pigment is C.I. I. Pigment Red81, C.I. I. Pigment Red 81: 4, C.I. I. The oil-based inkjet ink according to claim 4 or 5, which is one or more selected from the group consisting of Pigment Red 169. The silicone oil has an organic group having 2 to 6 silicon atoms in one molecule, a carbon atom directly bonded to the silicon atom, and a total of 5 or more carbon atoms and oxygen numbers, and has an organic group in one molecule. The invention according to any one of claims 1 to 6, which comprises a modified silicone oil having a total carbon number and oxygen number of 5 to 20 contained in an organic group having a total carbon number and oxygen number of 5 or more. Oil-based inkjet ink. The organic group contained in the modified silicone oil having a total of 5 or more carbon atoms and an oxygen number is an alkyl group having 7 or more carbon atoms and a carboxylic acid ester bond-containing group having a total of 5 or more carbon atoms and oxygen numbers. The oil-based inkjet ink according to claim 7, wherein the oil-based inkjet ink is one or more selected from the group consisting of an aromatic ring-containing group having 6 or more carbon atoms and an alkylene group having 7 or more carbon atoms. The oil-based inkjet ink according to claim 7 or 8, wherein the modified silicone oil is a compound represented by the following general formula (X).

(In the general formula (X), R ¹ is a divalent organic group in which a carbon atom is directly bonded to an oxygen atom or a silicon atom, and R ² is a divalent organic group in which a carbon atom is directly bonded to a silicon atom, respectively. M and n are independently integers of 0 to 4, p are independently integers of 0 to 2, and the number of silicon in one molecule is 2 to 6, ^{at least one of R 1} and R ² is an organic group having a total carbon number and oxygen number of 5 or more, and the total carbon number and oxygen number in one molecule is 5 or more. The total number of oxygen and carbon contained in the organic group is 5 to 20.)