JP2008231341A - Inkjet recording ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inkjet recording ink which is excellent in stability, has a high color-developing property on plain paper, and is excellent in ink discharging stability from an inkjet head. <P>SOLUTION: This inkjet recording ink is characterized by containing ≥0.1 to <5.0 wt.% of polyoxypropylene diglyceryl ether, wherein the propyleneoxy groups are contained in an amount of 1 to 50 groups per diglycerol molecule. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink for ink jet recording which has excellent stability, high color development on plain paper, and excellent ink ejection stability from an ink jet head.

  Inkjet recording is a method of recording characters and figures on the surface of a recording medium by ejecting ink as small droplets from fine nozzles. As an ink jet recording method, an electric signal is converted into a mechanical signal by using an electrostrictive element, and ink stored in the nozzle head portion is intermittently ejected to record characters and symbols on the surface of the recording medium. A method of recording characters and symbols on the surface of the recording medium, etc. by rapidly heating a part of the ink stored in the part and generating bubbles by rapidly heating a part very close to the ejection part. Has been put to practical use.

  The ink used for such ink-jet recording has no bleeding, good drying properties, can be printed uniformly on the surface of various recording media, color printing, etc. In color printing, characteristics such as that adjacent colors do not mix are required.

  Many conventional inks, especially those that use pigments, have been studied to ensure print quality by suppressing ink wetting on the paper surface mainly by suppressing permeability and keeping ink droplets near the paper surface. Made and put to practical use. However, with ink that suppresses wetting against paper, there is a large difference in bleeding due to the difference in the paper type, and especially with recycled paper in which various paper components are mixed, there is bleeding due to differences in ink wetting characteristics with respect to each component. appear. In addition, with such inks, it takes time to dry the print, and there is a problem that adjacent colors are mixed in multicolor printing such as color printing, and further, the pigment is applied to the surface of paper or the like. Since it remained, there also existed a subject that abrasion resistance worsened.

  In order to solve such problems, attempts have been made to improve the permeability of ink into paper. Addition of diethylene glycol monobutyl ether (see Patent Document 1), Surfynol 465, which is an acetylene glycol-based surfactant. The addition of Nissin Chemical (see Patent Document 2) or the addition of both diethylene glycol monobutyl ether and Surfynol 465 (see Patent Document 3) has been studied. In addition, the use of ethers of diethylene glycol for ink has been studied (see Patent Document 4).

  In addition, in the case of an ink using a pigment, it is generally difficult to improve the ink permeability while ensuring the dispersion stability of the pigment, and the range of selection of the penetrant is narrow. There are examples using triethylene glycol monomethyl ether (see Patent Document 5) and examples using ethylene glycol, diethylene glycol or triethylene glycol ethers (see Patent Document 6). There are also examples using 1,2-hexanediol, 1,2-octanediol, 2-methyl-2-propyl-1,3-propanediol, etc. (see Patent Document 7).

US Pat. No. 5,156,675 US Pat. No. 5,183,502 US Pat. No. 5,196,056 US Pat. No. 2,083,372 Japanese Patent Application Laid-Open No. 56-147861 Japanese Patent Laid-Open No. 9-111165 Japanese Patent Laid-Open No. 9-3371

  However, conventional water-based inks have insufficient print quality, and are often smeared when printed on plain paper such as PPC paper, and color density and color developability are also insufficient. In addition, conventional dispersions (which are pigments dispersed with a dispersant such as a polymer) are unstable. Ordinary water-based inks are usually free from surfactants and glycols to reduce bleeding on paper. Where substances having a hydrophilic part and a hydrophobic part such as ether are required, the presence or absence of these substances makes it easy for the polymer to be adsorbed and desorbed from the pigment, resulting in poor ink storage stability. On the other hand, with inks that do not use these substances, the permeability to paper is insufficient, and there is a problem that the type of paper is limited in order to perform uniform printing, which tends to cause a reduction in the printed image.

  Further, additives that can be used in the present invention (acetylene glycol type or acetylene alcohol type surfactants, di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether, or 1,2 -Use of alkylene glycol or a mixture thereof may cause problems that long-term storage stability cannot be obtained, and ink re-dissolvability is poor, so that the ink dries and easily clogs at the tip of an inkjet head nozzle. Was.

  Accordingly, the present invention solves such problems, and the object of the present invention is to provide ink for inkjet recording that has excellent stability, high color development on plain paper, and excellent ejection stability of ink from the inkjet head. Is to provide.

  The ink-jet ink of the present invention comprises 0.1% by weight or more and less than 5.0% by weight of polyoxypropylene diglyceryl ether.

  The present invention is based on the results of intensive studies in view of the demand for characteristics such as excellent stability, high color on plain paper, and excellent ejection stability of ink from an inkjet head.

  The ink for inkjet recording of the present invention is characterized by comprising 0.1% by weight or more and less than 5.0% by weight of polyoxypropylene diglyceryl ether. If the amount added is less than 0.1% by weight (hereinafter referred to as “%” unless otherwise specified), the color developability of plain paper is lowered, and if it is 5.0% or more, the ejection stability is deteriorated. The polyoxypropylene diglyceryl ether preferably has an average of 1 to 50 in terms of at least propyleneoxy per molecule of diglycerin. When propyleneoxy is in the above range, the ejection stability of ink from the inkjet nozzle is improved, and the glossiness is improved even on dedicated paper. More preferably, propyleneoxy is 9 or more and 30 or less per molecule of diglycerin. More preferably, propyleneoxy is 15 or more and 20 or less per molecule of diglycerin. Furthermore, polyoxyethylene polyoxypropylene diglyceryl ether can be used in the same manner as polyoxypropylene diglyceryl ether. Also in this case, it is preferable that propyleneoxy is in the above range (1 to 50) per molecule of diglycerin.

  This polyoxypropylene diglyceryl ether is commercially available, for example, as SC-P series of Sakamoto Pharmaceutical Co., Ltd.

  In this way, by preparing the ink for ink jet recording, it is possible to obtain an ink jet ink that produces high color on plain paper and has excellent ink ejection stability from the ink jet head.

  Color materials that can be used in the present invention include dyes and pigments. As the dye, a general dye that can be used for inkjet can be used. Examples include color dyes classified as oil-soluble dyes, basic dyes, etc. in addition to those classified as acid dyes, direct dyes, reactive dyes, vat dyes, disperse dyes, sulfur dyes or food dyes in the color index. An agent can also be used. In addition, as a pigment for black ink, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, or copper oxide, iron oxide (CI pigment) Examples include black 11), metals such as titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1). However, carbon black is preferable because it has a relatively low density and does not easily settle in water.

  For color inks, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 74, 81, 83 (Disazo Yellow HR), 93, 94, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 138, 153, 180, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 202, 206, 209, 219, . I. Pigment violet 19, 23, C.I. I. Pigment orange 36, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 56 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. can be used.

  As described above, it is preferable to use various dyes and pigments as the colorant, but more preferably, when the pigment is dispersed using a polymer, when the dye is permeated into the polymer, or polymer fine particles are used. This is the case of coexistence with a polymer.

  The addition amount of the coloring material used in the ink for ink jet recording of the present invention is preferably 0.5 to 30%, and more preferably 1.0 to 15%. If the addition amount is less than this, the print density cannot be ensured, and if the addition amount is more than this, the viscosity of the ink increases or structural viscosity is generated in the viscosity characteristics, and the ejection stability of the ink from the ink jet head tends to deteriorate. .

  Further, the ink-jet pigment ink in the present invention is a moisturizer or dissolution aid for the purpose of ensuring its standing stability, stable ejection from the ink-jet head, for improving clogging, or for preventing ink deterioration. Various additives such as chelating agents for trapping metal ions that affect dispersion, penetration control agents, viscosity modifiers, pH adjusters, dissolution aids, antioxidants, antiseptics, antifungal agents, corrosion inhibitors, and dispersion agents Can also be added.

  Hereinafter, specific embodiments of the present invention will be described. Examples are shown using pigments dispersed using the most preferred polymer, but dyes can be used in the same manner, and the present invention is not limited to these examples.

(Example 1)
(1) Production of Pigment Dispersion 1 As the pigment dispersion 1, Monarch 880 manufactured by Cabot Corporation of the United States, which is carbon black (Pigment Black 7), was used. The reaction vessel equipped with a stirrer, thermometer, reflux tube and dropping funnel was replaced with nitrogen, and then 75 parts of benzyl acrylate, 2 parts of acrylic acid and 0.3 part of t-dodecyl mercaptan were added and heated to 70 ° C. Disperse polymer while adding 150 parts of benzyl acrylate, 15 parts of acrylic acid, 5 parts of butyl acrylate, 1 part of t-dodecyl mercaptan, 20 parts of methyl ethyl ketone and 1 part of sodium persulfate to the reaction vessel over 4 hours. Was subjected to a polymerization reaction. Next, methyl ethyl ketone was added to the reaction vessel to prepare a dispersion polymer solution having a concentration of 40%. A portion of this polymer was taken out and dried, and then the glass transition temperature was measured by a differential operation calorimeter (EXSTAR6000DSC, manufactured by Seiko Denshi).

  Further, 40 parts of the above dispersion polymer solution, 30 parts of Monarch 880 powder (manufactured by Cabot) as carbon black, 100 parts of a 0.1 mol / L sodium hydroxide aqueous solution, and 30 parts of methyl ethyl ketone were mixed. Then, using an ultrahigh pressure homogenizer (Ultimizer HJP-25005 manufactured by Sugino Machine Co., Ltd.), the dispersion was performed by passing 15 passes at 200 MPa. Then, it moved to another container, 300 parts of ion exchange water was added, and also it stirred for 1 hour. And the whole amount of methyl ethyl ketone and a part of water were distilled off using the rotary evaporator, and it neutralized with 0.1 mol / L sodium hydroxide, and adjusted to pH9. Thereafter, it was filtered through a 0.3 μm membrane filter and adjusted with ion exchange water to obtain a pigment dispersion 1 having a pigment concentration of 15%.

(2) Production of Pigment Dispersion 2 First, Pigment Dispersion 2 was prepared in the same manner as Pigment Dispersion 1 using Pigment Blue 15: 4 (copper phthalocyanine pigment: manufactured by Clariant).

(3) Production of Pigment Dispersion 3 First, Pigment Dispersion 3 was prepared in the same manner as Pigment Dispersion 1 using Pigment Violet 19 (Quinacridone Pigment: Clariant).

(4) Production of Pigment Dispersion 4 First, Pigment Dispersion 3 was prepared in the same manner as Pigment Dispersion 1 using Pigment Yellow 74 (Condensed Azo Pigment: Clariant).

(5) Preparation of ink jet recording tank 1
Table 2 shows examples of compositions suitable for ink jet recording ink. The ink for inkjet recording of the present invention was prepared by using dispersions 1 to 4 prepared by the above method and mixing with the vehicle components shown in Table 2. The ink using pigment dispersion 1 was ink 1, the ink using pigment dispersion 2 was ink 2, the ink using pigment dispersion 3 was ink 3, and the ink using pigment dispersion 4 was ink 4. The remaining amount of water in Table 1 is 0.05% for the top side 240 (manufactured by Permachem Asia) for preventing ink corrosion, 0.02% for benzotriazole for preventing corrosion of the inkjet head member, In order to reduce the influence of metal ions in the ink, 0.04% EDTA (ethylenediaminetetraacetic acid) · 2Na salt was added to ion-exchanged water.

(6) Evaluation of plain paper OD 1
Xerox 4024 paper manufactured by US Xerox was used as plain paper. The printer used was an ink jet printer EM930C manufactured by Seiko Epson Corporation, and evaluation was performed using a sample printed in the photo 720 dpi printing mode. The OD was measured using GRETAG MACBETH SPECTROSCAN SPM-50 manufactured by GRETAG, USA. The results are shown in Table 1. Table 1 shows the result of comparison between Example 1 to which polyoxypropylene diglyceryl ether (hereinafter referred to as DGPO) was added and Comparative Example 1 to which DGPO was not added at the same time. The pigment dispersion 1 was used as ink 5, the pigment dispersion 2 was used as ink 6, the pigment dispersion 3 was used as ink 7, and the pigment and dispersion 4 was used as ink 8. . Examples of DGPO include DGPO6 (6PO adduct of diglycerin), DGPO15 (15PO adduct of diglycerin) and DGPO30 (30PO adduct of diglycerin), DGP014-EO5 (14PO adduct of diglycerin, and EO5 adduct) ) Is used.

(7) Measurement of discharge stability 1
Using PX-V600 manufactured by Seiko Epson Corporation as an inkjet printer, Microsoft Xerox P paper A4 size manufactured by Fuji Xerox Co., Ltd. at 35 ° C and 35% atmosphere, with a character size of 11 in Microsoft Word and MSP Gothic at a rate of 4000 characters / page The page was printed and evaluated. AA when there is no printing disorder at all, A with printing disorder at one place, B with printing disorder at 2-3 places, C at 4-5 printing disorders, and 6 or more printing disorders The results are shown in Table 1 with D as the result. At the same time, Comparative Example 1 was compared for the case where DGPO was not added.

(Example 2) to (Example 5)
(1) Preparation of Inkjet Ink with Different Addition of DGPO Examples 2 to 5 and Comparative Example 2 below are examples of compositions suitable for inkjet recording inks and cases where the addition of DGPO is changed as a comparative example. And 3 are shown in Tables 5 to 10. The ink for inkjet recording was prepared in the same manner as in Example 1.

(2) Evaluation of dispersion stability Dispersion stability was evaluated in the same manner as in Example 1. The results are shown in Table 4.

(3) Evaluation of plain paper OD Evaluation of plain paper OD was performed in the same manner as in Example 1. The results are shown in Table 4.

(4) Measurement of ejection stability The ejection stability was measured in the same manner as in Example 1. The results are shown in Table 4.

(Example 6)
(1) Preparation of ink for inkjet recording 2
Examples of ink compositions suitable for ink jet recording ink are shown in Table 11 below. Further, CW1 manufactured by Orient Chemical Co., Ltd. was used as a surface-treated carbon black pigment by using 5% of direct black 154 as a water-soluble dye 1 in terms of solid content, using 5% of direct yellow 132 as a water-soluble dye 2 in terms of solid content. As a pigment dispersion 5 as described in JP-A-2001-49155, [0035]. I. A vehicle component which is a component other than the above-mentioned colorants shown in Table 11 using 5% of pigment red 12 and Johncrill 61 (manufactured by Johnson), which are similarly dispersed using a styrene acrylic dispersant. Created by mixing with. The ink 33 using the water-soluble dye 1, the ink 34 using the water-soluble dye 2, the ink 35 using the surface-treated pigment 1, and the ink 36 using the pigment dispersion 5 were used.

(2) Evaluation of plain paper OD 2
Evaluation of plain paper was performed in the same manner as in Example 1. At the same time, Comparative Example 4 was compared for a sample in which DGPO was added in a total of 10%. In Comparative Example 4, ink 37 using water-soluble dye, ink 38 using water-soluble dye 2, ink 35 using water-soluble dye 3, ink 35 and water-soluble dye 4 using ink 40.

(3) Measurement of discharge stability 2
The ejection stability was measured in the same manner as in Example 1. At the same time, Comparative Example 4 was compared for a sample in which DGPO was added in a total of 10%.

Claims (2)

  An ink for ink jet recording comprising a coloring material, water, and 0.1% by weight or more and less than 5.0% by weight of polyoxypropylene diglyceryl ether.   The ink for inkjet recording according to claim 1, wherein the propyleneoxy of the polyoxypropylene diglyceryl ether has an average of 1 or more and 50 or less per molecule of diglycerin.