JP2014019766A - Nonaqueous inkjet ink and ink set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous ink that enables a printed of high concentration and high chroma to be obtained with a small discharge quantity.SOLUTION: A nonaqueous inkjet ink includes at least a pigment, an organic solvent and a dispersant, wherein the pigment is a xanthene-based pigment.

Description

  The present invention relates to a non-aqueous inkjet ink suitable for use in an inkjet recording system.

  The ink jet recording method is a recording method in which ink droplets are directly ejected from a very fine nozzle onto a recording member (printing medium) and adhered to obtain characters and images. This method is easy to make full color and inexpensive. It is rapidly spreading because it has many advantages such as low noise, high speed printing, and the ability to reduce costs because plain paper can be used as a recording member.

  As an ink used in the ink jet recording method, there is a so-called non-aqueous ink in which a pigment is finely dispersed in a non-aqueous solvent (organic solvent). This non-aqueous ink is obtained by dispersing a solid particle pigment in a low-viscosity solvent. Therefore, it is difficult to ensure the dispersion stability of the pigment, and when the aggregation of the pigment occurs, clogging occurs in the head nozzle, and as a result, stable ink ejection properties are obtained. There are problems such as not. In order to solve such a problem, the applicant has proposed a non-aqueous ink excellent in ejection stability in Patent Document 1.

  In recent years, particularly, the printing speed has been increased, and a method of printing in one pass using a line-type head has become widespread. Since the non-aqueous ink does not require a drying step, it is suitable as an ink for printing on a recording member in one pass in the ink jet recording method.

Japanese Patent No. 4837901

  However, the method of printing in one pass at high speed inevitably reduces the ink amount per unit area of the printed recording medium (printed material). In the first place, non-water-based inks have poorer colorant and solvent detachability than water-based inks, and the colorant easily penetrates into the paper together with the solvent. There is a problem that the degree decreases. For this reason, there has been a demand for ink that can provide a printed matter with high density and high saturation even with a small discharge amount.

  In general, when the ink discharge amount is small, the spread of dots is small and the solid image is not filled, so that the image density and the saturation are likely to decrease. If the proportion of the pigment in the ink is increased, a printed matter having a high image density can be obtained, but the saturation is lowered. In particular, this phenomenon is more likely to occur in non-water-based inks that are likely to penetrate paper, especially plain paper, than in water-based inks, and is particularly noticeable in the case of magenta-based inks.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-aqueous inkjet ink and an ink set that can obtain a printed matter with high density and high saturation even with a small discharge amount.

The non-aqueous ink-jet ink of the present invention is a non-aqueous ink-jet ink containing at least a pigment, a pigment dispersant and an organic solvent, wherein the pigment is a xanthene pigment.
The xanthene pigment is P.I. R. 81, P.I. R. 81: 1, P.I. R. 81: 2, P.I. R. 81: 3, P.I. R. 81: 4 and P.I. R. 169 is preferably at least one selected from 169.

The pigment may further contain an azo lake pigment.
The non-aqueous inkjet ink of the present invention preferably has a viscosity at 23 ° C. of 5 to 30 mPa · s.

  The non-aqueous ink set for an inkjet printer of the present invention is a combination of the non-aqueous inkjet ink described above and a non-aqueous inkjet ink containing at least one pigment selected from each pigment for cyan, yellow or black. It is characterized by.

  The non-aqueous ink-jet ink of the present invention is a non-aqueous ink-jet ink containing at least a pigment, a pigment dispersant, and an organic solvent, and the pigment is a xanthene-based pigment. High prints can be obtained.

  Further, according to the ink set in which the non-aqueous inkjet ink of the present invention is combined with the non-aqueous inkjet ink containing at least one pigment selected from cyan, yellow, or black pigments, the non-aqueous inkjet of the present invention is used. Since the density and saturation of the ink are improved, the color gamut, which is the color expression range, can be expanded when a mixed color is used.

It is the graph which showed the expression range of the color of the ink set using the ink of an Example and a comparative example.

  The non-aqueous ink-jet ink of the present invention is a non-aqueous ink-jet ink (hereinafter also simply referred to as ink) containing at least a pigment, a pigment dispersant, and an organic solvent, wherein the pigment is a xanthene pigment.

  The details of the xanthene pigment contained in the ink of the present invention are shown in Table 1 below. These pigments can be used alone or as a mixture. Among these, xanthene pigments are P.I. R. 81, P.I. R. 81: 1, P.I. R. 81: 2, P.I. R. 81: 3, P.I. R. 81: 4 and P.I. R. 169, preferably at least one selected from P.169. R. 81, P.I. R. 81: 1, P.I. R. 81: 4 and P.I. R. More preferably, it is at least one selected from 169.

  In the case of magenta ink, even if the discharge rate is increased and the proportion of the pigment is increased, the color becomes cloudy and the saturation is lowered. However, the ink of the present invention can obtain a high density and high saturation printed matter with a small discharge amount. In addition, by using a xanthene pigment, a high-density printed matter with high saturation can be obtained even if the discharge rate is increased and the proportion of the pigment is increased. In addition, even with 6 dpi solid at 300 dpi × 300 dpi, a printed matter with high OD and high saturation can be obtained. Further, in the case of an ink set in which the ink of the present invention is combined with cyan ink, yellow ink, or black ink, the mixed color gamut can be expanded by improving the density and saturation of magenta.

  The ink of the present invention may contain an azo lake pigment that can be used as a magenta color other than the xanthene pigment. The azo lake pigment that can be used in combination is preferably a soluble azo pigment. 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. And CI Pigment Red 247.

  The mass ratio of the xanthene pigment and the azo lake pigment is preferably 10: 0 to 3: 7, more preferably 10: 0 to 5: 5. If the mass ratio of the azo lake pigment is larger than this, it becomes difficult to obtain a high-saturated printed matter while achieving a high density, depending on the discharge amount. The total amount of these pigments is preferably 6 to 30% by mass and more preferably 6 to 20% by mass with respect to the total amount of ink.

  The organic solvent used in the ink of the present invention is not particularly limited, and examples thereof include conventionally known ones such as nonpolar organic solvents such as hydrocarbon solvents, polar organic solvents such as ester solvents, alcohol solvents, and higher fatty acid solvents. Can be used. These may be used alone or in combination of two or more. When using 2 or more types mixed, it is necessary for a liquid mixture to form a single continuous phase.

  Examples of the nonpolar organic solvent include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents. As the aliphatic hydrocarbon solvent and alicyclic hydrocarbon solvent, “Nippon Oil Co., Ltd.“ Tclean N-16, Tclean N-20, Tclean N-22, No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent ” "H, AF-4, AF-5, AF-6, AF-7" (all trade names), "Nisseki Isosol, Naphthezol" (all trade names) manufactured by Nippon Petrochemicals, "Exxon Mobil" IsoparG, IsoparH, IsoparL, IsoparM, ExxolD40, ExxolD80, ExxolD100, ExxolD140, ExxolD140 "(all trade names).

  As the polar organic solvent, ester solvents, alcohol solvents, higher fatty acid solvents, ether solvents, and mixed solvents thereof can be used. For example, selected from the group consisting of an ester solvent that is an ester of a higher fatty acid having 8 to 20 carbon atoms and an alcohol having 1 to 24 carbon atoms, a higher alcohol having 8 to 24 carbon atoms, and a higher fatty acid having 8 to 20 carbon atoms. One or more of them can be preferably used.

  Ester solvents include methyl laurate, isopropyl laurate, hexyl 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, diisopropyl adipate, diisopropyl sebacate, diethyl sebacate, propylene glycol monocaprate, tri-2-ethyl Examples include trimethylolpropane hexanoate and glyceryl tri-2-ethylhexanoate.

Examples of the alcohol solvent include isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, oleyl alcohol and the like.
Examples of the higher fatty acid solvent include isononanoic acid, isomyristic acid, isopalmitic acid, oleic acid, and isostearic acid.

  These non-aqueous solvents can be used alone or in combination of two or more. The addition amount of the organic solvent is preferably 60% by mass or more, and more preferably 70% by mass or more of the total amount of the ink.

  In the ink of the present invention, in addition to the organic solvent, a water-soluble organic solvent can be added as long as it is compatible with the ink and can form a single continuous liquid phase. The water-soluble organic solvent is not particularly limited, and conventionally known solvents such as lower alcohols can be used.

  The pigment dispersant is not particularly limited as long as it stably disperses the pigment to be used in the solvent, but among them, it is preferable to use a polymer dispersant. 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 pigment dispersants include “Solsperse 13940 (polyesteramine type), 17000, 18000 (fatty acid amine type), 11200, 22000, 24000, 28000” (all trade names) manufactured by Nippon Lubrizol Corporation. “Floren DOPA-15B” (trade name) manufactured by Kyoeisha Chemical Co., Ltd. “DA-703-50, DA-7300, DA234” (all trade names) manufactured by Enomoto Kasei Co., Ltd., “Disperbyk-101” manufactured by Byk Chemie (Trade name), “Hinoact” (trade name) manufactured by Kawaken Fine Chemical Co., Ltd., “Antaron V-216, Ganex V-216, Antaron V-220, Ganex V-220” (all trade names) manufactured by ISP, "Unimer U-1" manufactured by Inducem 1, Unimer U-15 "(all trade names).

  In addition to the above components, the ink of the present invention may contain conventional additives. Additives include surfactants such as anionic, cationic, amphoteric or nonionic surfactants, antioxidants such as dibutylhydroxytoluene, propyl gallate, tocopherol, butylhydroxyanisole, and nordihydroguaiare. And tic acid.

  The ink of the present invention can be prepared by, for example, supplying all components in a known disperser such as a bead mill in a batch or divided and dispersing them, and if desired, passing them through a known filter such as a membrane filter.

  The appropriate range of the viscosity of the ink varies depending on the nozzle diameter of the ejection head, the ejection environment, and the like, but is preferably 5 to 30 mPa · s at 23 ° C., more preferably 5 to 15 mPa · s, and more preferably 8 to More preferably, it is 12 mPa · s. Here, the viscosity represents a value at 10 Pa when the shear stress is increased from 0 Pa at a rate of 0.1 Pa / s at 23 ° C.

Since the ink of the present invention has a high print density, it is suitable for a line-type ink jet system for forming an image in one pass, and an ink set combining the ink of the present invention with cyan ink, yellow ink or black ink is used. Can be used. Here, the ink set includes not only an ink cartridge itself in which a plurality of ink cartridges are integrated, but also a case where a plurality of individual ink cartridges are used in combination, and further, an ink cartridge and a recording head are integrated. Is also included.
Examples of the non-aqueous inkjet ink of the present invention are shown below.

  Ink raw materials were mixed with the composition shown in Table 2 below (the numerical values shown in Table 2 are parts by mass), zirconia beads (diameter 0.5 mm) were added, and dispersed for 120 minutes with a rocking mill (Seiwa Giken Co., Ltd.). did. After dispersion, the zirconia beads were removed, and the particles were filtered through 3.0 μm and 0.8 μm membrane filters in order to remove dust and coarse particles, thereby preparing an ink composition.

  Here, the P.P. R. 81 is 108 First Rose Pink (manufactured by Harunagawa Pigment Co., Ltd.), P.I. R. 81: 4 is No. 9310 Pink (manufactured by Daido Kasei Kogyo Co., Ltd.), P.I. R. 169, Fanal Pink D4810 (manufactured by BASF), P.I. R. 57: 1 is ECR-102 (manufactured by Dainichi Seika Kogyo Co., Ltd.) and Solsperse 11200 is manufactured by Nippon Lubrizol Corporation.

(Examples and Comparative Examples)
The ink compositions thus prepared were prepared in the same manner as in Examples 1 to 6 and Comparative Example, and Examples 7 to 10 were prepared with the formulations shown in Table 3. Using the CB2 head (manufactured by Toshiba TEC), an ink jet method in which the prepared ink was printed in one pass with a line-type head, solid prints of 300 dpi × 300 dpi were produced with a drop volume of 24 pL and 30 pL at 1 dot, respectively.

(Evaluation)
(saturation)
One day after the printed material was produced, the saturation was measured with a color analyzer TC-1800MK-II manufactured by Tokyo Denshoku, and the measurement results were evaluated according to the following criteria. Note that the saturation is expressed by the following equation.
Saturation c * = {(a *) ² + (b *) ² } ^1/2
A: Saturation difference with Comparative Example 1 is 10 or more B: Saturation difference with Comparative Example 1 is 5 or more and less than 10 C: Saturation difference with Comparative Example 1 is 3 or more and less than 5 D: Comparison with Comparative Example 1 Saturation difference is less than 3

One day after the production of the printed material, measurement was performed with a reflection densitometer RD-918 manufactured by Gretag Macbeth, and the measurement result was evaluated according to the following criteria.
A: Difference from Comparative Example 1 is 0.1 or more B: Difference from Comparative Example 1 is from 0.05 to less than 0.1 C: Difference from Comparative Example 1 is from 0.03 to less than 0.5 D: Comparison The difference from Example 1 is less than 0.03. Table 3 shows the formulation and evaluation results for each ink.

  In Examples 1 to 6, since the pigment was a xanthene pigment, a printed matter having a high concentration and high saturation could be obtained. Examples 7 to 11 are inks containing brilliant carmine 6B (PR 57: 1) as an azo lake pigment in addition to the xanthene pigment, but when the content of brilliant carmine 6B is half or more, Although a slight decrease in saturation was observed, a printed matter having a high density and high saturation could be obtained. On the other hand, in Comparative Examples 1 and 2 using only brilliant carmine 6B, the OD concentration was low and the saturation was also low. In Comparative Examples 3 and 4 in which the amount of brilliant carmine 6B was increased, when the droplet amount was 24 pL, the OD concentration was higher than in Comparative Examples 1 and 2, but the saturation remained low.

  Two ink sets were prepared in which yellow, cyan, and black were combined with each of the magenta inks of Example 4 and Comparative Example 2 (Yellow, cyan, and black inks were manufactured by our company). Using this ink set, blue, cyan, green, magenta, red, and yellow were printed with ORPHIS X9050 (trade name; manufactured by Riso Kagaku Kogyo Co., Ltd.). L * a * b * of the obtained printed matter was measured with a color analyzer TC-1800MK-II manufactured by Tokyo Denshoku. The measured values of a * and b * for each color are shown in Table 4, and a graph showing the color expression range by plotting a * on the horizontal axis and b * on the vertical axis is shown in FIG.

  As shown in Table 4 and FIG. 1, in the ink set using the ink of the example, the density and saturation of the magenta ink are improved as compared with the ink set using the ink of the comparative example. In this case, it can be seen that the color gamut is widened in the hatched portion.

Claims (3)

  A non-aqueous inkjet ink comprising at least a pigment, a pigment dispersant, and an organic solvent, wherein the pigment is a xanthene pigment.   The xanthene pigment is P.I. R. 81, P.I. R. 81: 1, P.I. R. 81: 2, P.I. R. 81: 3, P.I. R. 81: 4 and P.I. R. The non-aqueous inkjet ink according to claim 1, wherein the non-aqueous inkjet ink is at least one selected from 169.   The non-aqueous inkjet ink according to claim 1 or 2, wherein the pigment further contains an azo lake pigment.