JP2009275211A - Non aqueous pigment ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous pigment ink which can suppress corrugation of a clear file by a printed matter. <P>SOLUTION: The non-aqueous pigment ink contains a pigment, a pigment dispersant and a non-aqueous solvent, in which an ester of a polyhydric alcohol and a branched chain aliphatic carboxylic acid or an ester more than a diester of a branched aliphatic alcohol and a polyvalent aliphatic carboxylic acid are contained as the non-aqueous solvent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-aqueous pigment ink, and more particularly to a non-aqueous pigment ink suitable for use in an inkjet recording system.

The ink jet recording system is applied to various printing fields because it can form an image easily and inexpensively. In offices, it is desired to perform high-speed printing on plain paper using this system.
In general, water-based (water-based) ink is used as ink-jet ink. However, when printing on plain paper, the paper curls due to moisture in the ink, and this has a significant effect on paper transport, especially when high-speed printing is performed. The harmful effect of giving rises.

On the other hand, the non-aqueous (oil-based) ink does not contain water in the ink, and therefore does not curl the paper even when printing on plain paper, and is therefore suitable for high-speed printing.
Japanese Patent Application Laid-Open No. 2003-261808 discloses a non-aqueous ink with improved ink storage stability, in which the solvent contains 60% by weight or more of a polar organic solvent, and the polar organic solvent contains 10% by weight or more of an ester solvent. Disclose.

  Japanese Patent Laid-Open No. 2002-363465 has high stability, high safety, high concentration, high definition, and excellent water resistance by using a dispersion medium composed of a branched ester having 10 to 22 carbon atoms. Disclosed is an ink-jet non-aqueous pigment ink capable of forming an image.

JP 2003-261808 A JP 2002-363465 A

However, it has been found that if a printed matter printed with a conventional non-aqueous ink is sandwiched between clear files that are normally used in offices and homes, the file undulates over time.
Accordingly, an object of the present invention is to provide a non-aqueous pigment ink that can solve such a problem of clear file ripples.

According to one aspect of the present invention, comprising a pigment, a pigment dispersant, and a non-aqueous solvent,
There is provided a non-aqueous pigment ink containing, as the non-aqueous solvent, an ester of a polyhydric alcohol and a branched aliphatic carboxylic acid or a diester or more of a branched aliphatic alcohol and a polyvalent aliphatic carboxylic acid.

  The non-aqueous pigment ink according to the present invention (hereinafter sometimes simply referred to as “ink”) includes, as a non-aqueous solvent, a diester or higher ester of a polyhydric alcohol and a branched chain aliphatic carboxylic acid, or a branched chain fatty acid. In this case, it is possible to realize an ink that does not cause the problem of waviness of the clear file by using an ester not less than a diester of an aliphatic alcohol and a polyvalent aliphatic carboxylic acid.

The ink according to the present invention includes a pigment, a pigment dispersant, and a non-aqueous solvent as essential components.
Examples of the pigment include organic pigments such as azo, phthalocyanine, dye, condensed polycyclic, nitro, and nitroso (brilliant carmine 6B, lake red C, watching red, disazo yellow, hanza yellow, phthalocyanine blue, Phthalocyanine green, alkali blue, aniline black, etc.); metals such as cobalt, iron, chromium, copper, zinc, lead, titanium, vanadium, manganese, nickel, metal oxides and sulfides, and ocher, ultramarine, bitumen, etc. Carbon blacks such as inorganic pigments, furnace carbon black, lamp black, acetylene black and channel black can be used. Any one of these pigments may be used alone, or two or more of these pigments may be used in combination.

The average particle diameter of the pigment is preferably 300 nm or less, more preferably 150 nm or less, and further preferably 100 nm or less from the viewpoints of dispersibility and storage stability. Here, the average particle diameter of the pigment is a value measured by a dynamic light scattering particle size distribution analyzer LB-500 manufactured by Horiba, Ltd.
The content of the pigment in the ink is usually 0.01 to 20% by weight, preferably 1 to 15% by weight, and more preferably 5 to 10% by weight from the viewpoint of printing density and ink viscosity. .

  The pigment dispersant to be blended is not particularly limited as long as the pigment is stably dispersed in the solvent. For example, hydroxyl group-containing carboxylic acid ester, long chain polyaminoamide and high molecular weight acid ester salt, high molecular weight polycarboxylic acid salt, long chain polyaminoamide and polar acid ester salt, high molecular weight unsaturated acid ester, high molecular weight copolymer , Modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl phenyl ether, polyester polyamine, stearylamine acetate, etc. Of these, the use of a polymer dispersant is preferred. These may be used alone or in combination of two or more.

Specific examples of commercially available dispersants include:
“Solsperse 5000 (phthalocyanine ammonium salt type), 13940 (polyesteramine type), 17000, 18000 (fatty acid amine type), 11200, 22000, 24000, 28000” (all trade names) manufactured by Nippon Lubrizol Co., Ltd .;
“Efka CHEMICALS” “Efka 400, 401, 402, 403, 450, 451, 453 (modified polyacrylate), 46, 47, 48, 49, 4010, 4055 (modified polyurethane)” (both products) Name);
“Demol P, EP, Poise 520, 521, 530, Homogenol L-18 (polycarboxylic acid type polymer surfactant)” manufactured by Kao Corporation (all trade names);
“Disparon KS-860, KS-873N4 (amine salt of polymer polyester)” manufactured by Enomoto Kasei Co., Ltd. (both are trade names);
"Discall 202, 206, OA-202, OA-600 (multi-chain polymer nonionic)" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (all trade names);
Etc.

The blending amount of the pigment dispersant in the ink can be set as appropriate, but from the viewpoint of pigment dispersibility, the weight ratio is preferably about 0.05 to 1.0 part with respect to 1 part of the pigment, 0.1 More preferably, it is -0.7 part.
The pigment dispersant is preferably contained in an amount of about 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the total amount of ink.

Next, the non-aqueous solvent will be described. The non-aqueous solvent is a non-polar organic solvent or a polar organic solvent having a 50% distillation point of 150 ° C. or higher. The 50% distillation point means a temperature at which 50% by weight of a solvent is volatilized, which is measured according to JIS K0066 “Testing method for distillation of chemical products”.
For example, preferred examples of the nonpolar organic solvent include aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents and the like. Examples of the aliphatic hydrocarbon solvent and alicyclic hydrocarbon solvent include, for example, “Teclean N-16, Teclean N-20, Teclean N-22, Naphthezol L, Naphthezol M, Naphthezol H, manufactured by Nippon Oil Corporation. 0 Solvent L, 0 Solvent M, 0 Solvent H, Isosol 300, Isosol 400, AF-4, AF-5, AF-6, AF-7, “Isopar G, Isopar” manufactured by Exxon Mobil Preferable examples include H, Isopar L, Isopar M, Exxsol D40, Exxsol D80, Exxsol D100, Exxsol D130, Exxsol D140.

  As the polar organic solvent, ester solvents, alcohol solvents, higher fatty acid solvents, ether solvents, and mixed solvents thereof can be used. More specifically, methyl laurate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate, methyl linoleate, isobutyl linoleate , Ethyl linoleate, isopropyl isostearate, soybean oil methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, diethyl sebacate, propylene glycol monocaprate, trimethylolpropane tri-2-ethylhexanoate, tri-2-ethylhexane Ester solvents such as glyceryl acid; alcohol solvents such as isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, oleyl alcohol; isononanoic acid, Preferred are higher fatty acid solvents such as somyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid and isostearic acid; ether solvents such as diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether and propylene glycol dibutyl ether It is done.

In the present invention, among these non-aqueous solvents, an ester (1) or more of a diester of a polyhydric alcohol and a branched aliphatic carboxylic acid, or an ester or more of a diester of a branched aliphatic alcohol and a polyvalent aliphatic carboxylic acid. (2) is included. By using this specific ester (1) or (2), the ink according to the present invention can suppress the waviness of the clear file due to contact with the obtained printed matter. Currently, most clear files used in offices and homes are made of polypropylene.
The wavyness of the clear file is considered to be caused by the non-aqueous solvent in the ink penetrating into the resin constituting the file when the printed material is sandwiched inside, and as a result, the file swells. This is because, unlike an aqueous solvent, a non-aqueous solvent generally has a high affinity with a resin.

In order to suppress penetration into the resin, for example, if a solvent having a high viscosity is used, it may be difficult to penetrate into the resin. There is a problem in terms of.
On the other hand, an ester (1) or more of a diester of a polyhydric alcohol and a branched aliphatic carboxylic acid or an ester (2) of a diester or more of a branched aliphatic alcohol and a polyvalent aliphatic carboxylic acid has an ink viscosity. It is characterized by being able to achieve both suppression and suppression of file swelling.

Examples of branched aliphatic carboxylic acids include 2-methylpropionic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2-ethylbutanoic acid, isoheptanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, isododecanoic acid, isomyristic acid, iso Examples include palmitic acid, isostearic acid, isoarachidic acid, isohexaconic acid and the like. The branch position and the number of branches are not particularly limited.
From the viewpoints of ink viscosity and suppression of clear file swelling, the branched chain aliphatic carboxylic acid preferably has 4 to 12 carbon atoms, more preferably 6 to 10 carbon atoms.
Further, the branched chain aliphatic carboxylic acid is preferably a monocarboxylic acid from the viewpoint of the storage stability of the ink, and is a saturated carboxylic acid from the viewpoint of storage stability when the ink is left in an open system. Is preferred.

As the polyhydric alcohol, aliphatic alcohol is preferable, ethylene glycol, propylene glycol, isopropylene glycol, 1,3-propanediol, diethylene glycol, 1,3-butylene glycol, 1,4-butanediol, 2,3-butane. Diol, 1,2-pentanediol, 2,2-dimethylpropane-1,3-diol, 1,5-pentanediol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1, Examples include dihydric alcohols such as 3-cyclohexanedimethanol, 1,9-nonanediol, and 1,10-decanediol; trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane; and tetrahydric alcohols such as pentaerythritol. .
From the viewpoint of ink viscosity, ethylene glycol, propylene glycol, isopropylene glycol, 1,3-propanediol, diethylene glycol, 1,3-butylene glycol, 1,4-butanediol, and 2,3-butanediol, A polyhydric alcohol having 2 to 4 carbon atoms is preferred.

The ester of the branched chain aliphatic carboxylic acid and the polyhydric alcohol is required to be diester or more from the viewpoint of suppressing the waviness of the clear file, and in the case of the trivalent or higher alcohol, from the viewpoint of suppressing the clear file swelling. The neutral ester in which all hydroxyl groups are esterified is preferable.
Diesters of diisooctanoic acid can be used as particularly preferable esters, and examples thereof include propylene glycol diisooctanoate and 1,3-butylene glycol diisooctanoate.

Examples of branched aliphatic alcohols include isopropanol, isobutanol, 2-butanol, t-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-pentanol, and 4-methyl-2-pentanol. 2-ethylbutanol, 2-heptanol, 3-heptanol, 2-octanol, 2-ethylhexanol, 2,6-dimethyl-4-heptanol, 2-decanol, trimethylnonyl alcohol and the like. The branch position and the number of branches are not particularly limited.
From the viewpoint of ink viscosity and suppression of clear file swelling, the branched chain aliphatic alcohol preferably has 3 to 12 carbon atoms, and more preferably 6 to 10 carbon atoms.
Furthermore, the branched chain aliphatic alcohol is preferably a monoalcohol from the viewpoint of the storage stability of the ink, and is preferably a saturated alcohol from the viewpoint of the storage stability when the ink is left in an open system.

As polyvalent aliphatic carboxylic acids, oxalic acid, malonic acid, fumaric acid, maleic acid, succinic acid, glutaric acid, glutaconic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, terephthalic acid And divalent carboxylic acids such as isophthalic acid; and trivalent carboxylic acids such as trimellitic acid.
From the viewpoint of ink viscosity and storage stability when the ink is left in an open system, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid Dicarboxylic acids such as are preferred.

The specific esters (1) and (2) may be used in combination of two or more. The content of the ester in the ink is preferably 50 to 80% by weight as the total amount when a plurality of types are included.
The ink may further contain the above-described nonpolar organic solvent as a nonaqueous solvent. The content of the nonpolar organic solvent in the ink is preferably 30% by weight or less.
Furthermore, a polar organic solvent other than the above specific ester may be used in the ink in an amount of 30% by weight or less within a range that does not impair the effects of the present invention.

In addition to the above-described components, the ink can contain various additives that are usually used in the art as long as they do not impair the object of the present invention.
Specifically, as an antifoaming agent, a surface tension reducing agent, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or a polymer-based, silicone-based, or fluorine-based surfactant. An agent can be contained in the ink.

  By blending an antioxidant, it is possible to prevent the ink components from being oxidized and improve the storage stability of the ink. As the antioxidant, for example, L-ascorbic acid, sodium L-ascorbate, sodium isoascorbate, potassium sulfite, sodium sulfite, sodium thiosulfate, sodium dithionite, sodium pyrosulfite can be used.

  By blending a preservative, the ink can be prevented from being spoiled and the storage stability can be improved. Examples of preservatives include 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, and 1 Isothiazolone preservatives such as 1,2-benzisothiazolin-3-one; triazine preservatives such as hexahydro-1,3,5-tris (2-hydroxyethyl) -s-triazine; 2-pyridinethiol sodium-1- Pyridine / quinoline preservatives such as oxide and 8-oxyquinoline; Dithiocarbamate preservatives such as sodium dimethyldithiocarbamate; 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitro-1,3 -Propanediol, 2,2-dibromo-2-nitroethanol, 1,2-dibromo-2,4-dicia Brominated organic preservatives such as butane; p-hydroxybenzoate, p- hydroxybenzoate ethyl, potassium sorbate, sodium dehydroacetate, can be used salicylic acid.

The ink can be produced, for example, by first preparing a pigment dispersion containing a pigment, a pigment dispersant, and a non-aqueous solvent, and further adding a non-aqueous solvent and other optional components. Or you may mix all the compounding components at once.
A pigment dispersion or ink containing a pigment, a dispersant, and a non-aqueous solvent can be preferably obtained by mixing these three components and dispersing the pigment using any dispersing means such as a ball mill or a bead mill.

  The viscosity of the ink when used for an ink jet recording apparatus has a suitable range depending on the nozzle diameter of the discharge head, the discharge environment, and the like, but in general, it is preferably 2 to 30 mPa · s at 23 ° C. More preferably, it is 15 mPa · s. Here, the viscosity represents a value when the shear stress is increased from 0 Pa to 10 Pa over 1 minute at 23 ° C.

  The printing method using the ink of the present invention is not particularly limited, but is preferably performed using an ink jet recording apparatus. The ink jet printer may be of any system such as a piezo system, an electrostatic system, or a thermal system. When an ink jet recording apparatus is used, the ink according to the present invention is ejected from the ink jet head based on a digital signal, and the ejected ink droplets are attached to the recording medium.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
<Examples and Comparative Examples>
Each compounding component shown in Table 1 was put in a 250 ml polypropylene container and mixed, 450 g of zirconia beads (diameter 0.5 mm) was added, and dispersed for 60 minutes by a rocking mill (Seiwa Giken Co., Ltd.). Thereafter, zirconia beads were separated by filtration, and the obtained contents were filtered through a 3.0 μm and 0.8 μm membrane filter to remove dust and coarse particles, thereby obtaining each ink.
The carbon black used is “MA11” manufactured by Mitsubishi Chemical Corporation, the pigment dispersant is “Solsperse S-11200” manufactured by Nippon Lubrizol Co., Ltd., and the petroleum hydrocarbon solvent is Mitsubishi Oil Corporation. “AF7” (naphthenic solvent)
All of the obtained inks had a pigment particle size in an appropriate range as an inkjet ink.

<Viscosity measurement>
The viscosity of the ink obtained above (viscosity when the shear stress is increased from 0 Pa to 10 Pa over 1 minute at 23 ° C.) was used using a stress-controlled rheometer RS75 (cone angle: 1 °, diameter: 60 mm) manufactured by Haake. Measured.

<Dischargeability>
“HC5500” (Riso Kagaku Kogyo Co., Ltd.) was used as the ink jet recording apparatus, and the ejection properties were evaluated as follows. The HC5500 uses a 300 dpi line-type inkjet head (each nozzle is arranged at an interval of about 85 μm), and performs printing by transporting paper in the sub-scanning direction orthogonal to the main scanning direction (direction in which the nozzles are arranged). System.
Each ink was loaded into an ink jet recording apparatus, a solid image corresponding to 300 dpi was printed, and the presence or absence of a white line due to ejection failure in the printed image was visually evaluated. A sample with no white line was designated as A, and a sample with white line was designated as C.

<Clear file swelling>
In the same manner as described above, a solid image was printed on an area of 1/3 of A4 size plain paper. A polypropylene sheet (thickness: 140 μm) was placed on the obtained printed matter and allowed to stand at 30 ° C. for 10 days under a weight of 500 g.
When the polypropylene sheet was allowed to stand on a horizontal surface, the warp was less than 1 cm, AA was evaluated, and 1 cm or more and less than 2 cm was evaluated as A, and 2 cm or more was evaluated as C.
The above results are also shown in Table 1.

The inks of the examples were found to have good ejection properties and no problem with clear file swelling (waving).
On the other hand, it was found that the inks of Comparative Examples 1 and 2 using a conventional polar organic solvent caused significant clear file swelling. Although the ink of Comparative Example 3 has no problem in terms of swelling of the clear file, it has been found that it is unsuitable for inkjet use in terms of ejection properties.

Claims (7)

Containing a pigment, a pigment dispersant and a non-aqueous solvent,
A non-aqueous pigment ink containing, as the non-aqueous solvent, an ester of a polyhydric alcohol and a branched aliphatic carboxylic acid or a diester or more of a branched aliphatic alcohol and a polyvalent aliphatic carboxylic acid.   The non-aqueous pigment ink according to claim 1, wherein a content of the ester in the ink is 50 to 80% by weight.   The non-aqueous pigment ink according to claim 1 or 2, wherein the branched chain aliphatic carboxylic acid is an aliphatic carboxylic acid having 4 to 12 carbon atoms.   The non-aqueous pigment ink according to claim 1 or 2, wherein the branched chain aliphatic alcohol is an aliphatic alcohol having 3 to 12 carbon atoms.   The polyhydric alcohol is selected from the group consisting of ethylene glycol, propylene glycol, isopropylene glycol, 1,3-propanediol, diethylene glycol, 1,3-butylene glycol, 1,4-butanediol, and 2,3-butanediol. The non-aqueous pigment ink according to claim 1, which is at least one selected.   The polyvalent aliphatic carboxylic acid is at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Item 5. The non-aqueous pigment ink according to item 1, 2 or 4.   The non-aqueous pigment ink according to claim 1, further comprising a non-polar organic solvent as the non-aqueous solvent.