JP2005263969A - Ink composition - Google Patents

Abstract

【化２】

【選択図】 なし
PROBLEM TO BE SOLVED: To provide an ink composition capable of realizing good printing quality on plain paper in an ink jet recording method, in particular, ensuring high printing density and edge sharpness, and further having very little ejection stability and printing unevenness.
An ink composition comprising at least a resin-dispersed pigment, a compound represented by the following formula (1), a compound represented by the following formula (2), and water. To perform ink jet recording.
[Chemical 1]

[Chemical 2]

[Selection figure] None

Description

  The present invention provides good print quality on plain paper, particularly high O.D. D. The present invention relates to a pigment ink composition suitable for ink jet recording that realizes an (optical density) value and edge sharpness, has very little printing unevenness, and further ensures ejection stability.

  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. Further, there is still a demand for realizing high print quality on plain paper that is inexpensive and widely spread.

  In general, inks in which various water-soluble dyes are dissolved in an aqueous medium are used. It has been generally pointed out that an image formed with an ink containing such a water-soluble dye is inferior in water resistance and light resistance. An ink using a pigment as a colorant is also provided. A pigment-based ink in which a pigment is dispersed in an aqueous medium has a feature of being excellent in water resistance and light resistance as compared with a water-soluble dye. Therefore, an aqueous pigment ink dispersed with a surfactant or a polymer dispersant has been proposed.

  However, when examining ink-jet ink formulation, surfactants, solvents, etc. for print quality (especially OD (optical density) value, edge sharpness, print unevenness) and reliability (particularly ejection stability) Susceptible to additives. In particular, when a pigment is used as a colorant, the line width is difficult to increase in print quality, and an image with a noticeable streak is likely to occur. D. The (optical density) value is low and uneven printing is likely to occur, and the edge sharpness is often noticeable. Moreover, considering the reliability aspect, the influence is still great, including discharge stability.

  Thus, silicon-based and acetylene glycol-based surfactants, glycol ethers, and diol-based solvents are known as additives. Several ink compositions containing these additives are also known. For example, an inkjet recording ink composition containing a modified polysiloxane having a specific structure (see, for example, Patent Documents 1 and 2), and a dye-based ink composition containing a diol-based solvent (see, for example, Patent Document 3) It has been known.

  However, not all additives of the same line as the above-mentioned literature are effective, especially in the case of pigment dispersions, which depend greatly on the compatibility with the additives and depend on reliability such as print quality and ejection stability. It was difficult to select and combine effective additives including properties. Above all, the above-mentioned various surfactants are being studied to increase line width, print unevenness, and edge sharpness in print quality, but those that are effective are generally not soluble in water, so they have reliability such as ejection stability. It was difficult to use because there were many problems in terms of nature.

JP-A-5-169790 Japanese Patent Laid-Open No. 10-310732 Japanese Patent Laid-Open No. 10-279871

  The present invention has been made in view of the above problems, and in the ink jet recording method, it is possible to realize good print quality on plain paper, particularly high O.D. D. An object of the present invention is to provide a pigment ink composition suitable for ink jet recording, which realizes value and edge sharpness, has very little printing unevenness, and further ensures reliability such as ejection stability.

  According to the ink composition comprising at least two types of silicon surfactants having a specific structure, the present inventor achieves good print quality, that is, high O in ink jet recording. . D. The value (optical density) and edge sharpness were realized, printing unevenness was extremely small, and high reliability was ensured for printing stability.

  The ink composition according to the present invention comprises at least a resin-dispersed black pigment and a compound represented by the following formula (1) and the following formula (2).

  The ink composition according to the present invention further comprises 1,2-hexanediol.

  According to the present invention, good print quality, particularly high O.D. D. Value and edge sharpness are obtained, and reliability such as ejection stability is ensured, and a suitable pigment ink composition with very little printing unevenness is obtained.

  The ink composition according to the present invention is used in a recording system using the ink composition.

  In particular, the ink composition according to the present invention is preferably used in an ink jet recording method.

  The aqueous ink composition of the present invention comprises at least an aqueous medium, a resin-dispersed pigment, a compound represented by the formula (1), and a compound represented by the formula (2).

  The aqueous ink composition of the present invention further comprises 1,2-hexanediol.

  Hereinafter, each component will be described in detail.

  The ink composition according to the present invention comprises a resin dispersed pigment.

  The resin-dispersed pigment in the present invention is contained in the aqueous ink composition as a colorant, and any of inorganic pigments and organic pigments can be used. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Organic pigments include azo dyes (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinofuranone pigments, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used.

  Specific examples of the pigment include carbon black, No. manufactured by Mitsubishi Chemical Corporation. 2300, no. 900, HCF88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B, etc. are Raven 5750, 5250, 5000, 3500, 1255, 700, etc., manufactured by Columbia, etc., Regal 400R, 330R, 660R, Mogu L, 700, Monarch 800, 880, 900, 1000, 1100, 1300, 1400, etc. are Degussa Color Black FW1, FW2, FW2V, FW18, FW200, Color Black S150, S160, S170, Printex. 35, U, V, 140U, Special Black 6, 5, 4A, 4 and the like.

  Examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185 and the like.

  Examples of pigments used for magenta ink include C.I. I. Pigment red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 15: 1, 112, 122, 123, 168, 184, 202, 209 and the like.

  Further, examples of pigments used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15:34, 16, 22, and 60.

  According to a preferred embodiment of the present invention, the pigment preferably has an average particle size in the range of 10 to 200 nm, more preferably about 50 to 150 nm.

  The amount of the pigment added may be appropriately determined, but is preferably in the range of 0.1 to 20% by weight, more preferably in the range of 1 to 10% by weight with respect to the ink composition.

  In the present invention, the pigment is preferably added to the ink composition as a pigment dispersion dispersed by a dispersant. An example of the dispersant is a polymer dispersant.

  Preferable examples of the polymer dispersant include synthetic polymers such as styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methyl. Examples thereof include styrene-acrylic acid resins such as styrene-acrylic acid copolymer and styrene-α-methylstyrene-acrylic acid-alkyl acrylate copolymer. Among these, the styrene-acrylic acid resin, which is a polymer compound having a carboxyl group (preferably in the form of a salt), is a co-polymerization of a monomer having a hydrophobic group and a monomer having a hydrophilic group. A polymer and a polymer composed of a monomer having both a hydrophobic group and a hydrophilic group in the molecular structure are preferred. Examples of the salt include salts with diethylamine, ammonia, ethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, triethanolamine, diethanolamine, aminomethylpropanol, morpholine and the like. These copolymers preferably have a weight average molecular weight of 3,000 to 30,000, more preferably 5,000 to 15,000.

  The ink composition according to the present invention comprises the compound of the above formula (1).

  In the formula (1), EO represents an ethyleneoxy group, PO represents a propyleneoxy group, m represents an integer of 3 or less, and n represents an integer of 2 or less. Preferably m + n is 1-4.

  The amount of the compound of formula (1) may be appropriately determined, but is preferably in the range of about 0.03 to 1% by weight, more preferably in the range of about 0.05 to 0.5% by weight.

  The compound of formula (1) is commercially available and can be used. For example, a silicon surfactant BYK-347 and the like can be used from Big Chemie Japan Co., Ltd.

  The ink composition according to the present invention comprises the compound of the above formula (2).

  In the formula (2), EO represents an ethyleneoxy group, PO represents a propyleneoxy group, m represents an integer of 4 or more, and n represents an integer of 3 or more. Preferably m + n is 7-15. The amount of the compound of formula (2) may be appropriately determined, but is preferably in the range of about 0.05 to 2% by weight, more preferably in the range of about 0.1 to 1% by weight with respect to the ink composition. is there.

  The compound of formula (2) is commercially available and can be used. For example, silicon surfactants BYK-345, BYK-348, etc. can be used from Big Chemie Japan Co., Ltd.

  According to a preferred embodiment of the present invention, the ink composition according to the present invention preferably further comprises 1,2-hexanediol. The amount of 1,2-hexanediol added may be appropriately determined, but is preferably about 0.5 to 10% by weight, more preferably about 1 to 5% by weight.

  With respect to the compound represented by the above formula (1), the compound represented by the formula (2), and 1,2-hexanediol, if the addition amount is too small, the improvement improvement effect on the printing quality does not appear, and if it is too much, it is reliable. The additive amount is a preferable addition range because it adversely affects the properties.

  In the ink composition of the present invention, the water can be pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water. In addition, the use of water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be prevented when the ink composition is stored for a long period of time.

  The water-soluble organic solvent is preferably a low-boiling organic solvent, and examples thereof include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, sec-butanol, tert-butanol, iso- Examples include butanol and n-pentanol. A monohydric alcohol is particularly preferable. The low boiling point organic solvent has an effect of shortening the drying time of the ink. The amount of the low-boiling organic solvent added is preferably in the range of about 5% by weight or less, more preferably in the range of about 2% by weight or less with respect to the ink composition.

  According to a preferred embodiment of the present invention, the ink composition according to the present invention preferably further comprises a wetting agent comprising a high boiling point organic solvent. Preferred examples of the high boiling point organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, triglyceride, And polyhydric alcohols such as methylolethane and trimethylolpropane, urea, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and the like. It can be used as a mixture. Among these, glycerin, 2-pyrrolidone, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and urea are preferable. These addition amounts are preferably in the range of about 1 to 20% by weight, more preferably in the range of about 5 to 10% by weight with respect to the ink composition.

  According to a preferred embodiment of the present invention, the ink composition according to the present invention comprises a penetrant. Preferable specific examples of the penetrant include glycol ethers.

  Specific examples of glycol ethers used in the present invention include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n- Propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n- Butyl ether, diethylene glycol mono-t- Chill ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol Mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether and the like, It can be used as a mixture of two or more. Among these, triethylene glycol mono-n-butyl ether is particularly preferably used. The amount of glycol ether added is preferably in the range of 1 to 20% by weight, more preferably in the range of 2 to 15% by weight, based on the ink composition.

  The ink composition according to the present invention may further contain a nozzle clogging preventive agent, an antiseptic, an antioxidant, a conductivity adjusting agent, a pH adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorber, and the like. it can.

  Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzthiazoline-3-one ( ICI's Proxel CRL, Proxel BND, Proxel GXL, Proxel XL-2, Proxel TN) and the like.

  Furthermore, examples of pH adjusters, solubilizers or antioxidants include amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, potassium hydroxide, sodium hydroxide, lithium hydroxide. Inorganic salts such as ammonium hydroxide, quaternary ammonium hydroxide (such as tetramethylammonium), carbonates such as potassium carbonate, sodium carbonate, lithium carbonate, and other phosphates, or N-methyl-2-pyrrolidone, urea, Examples include L-ascorbic acid and salts thereof, such as ureas such as thiourea and tetramethylurea, allophanates such as allophanate and methylallohanate, and biurets such as biuret, dimethylbiuret and tetramethylbiuret.

  In addition, the ink composition according to the present invention may contain an antioxidant and an ultraviolet absorber, examples of which include Ciba Geigy's Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024, lanthanide oxide, and the like.

  The aqueous ink composition of the present invention can be prepared in the same manner as conventional inks using a conventionally known apparatus such as a ball mill, a sand mill, an attritor, a basket mill, and a roll mill. In the adjustment, it is preferable to remove coarse particles from the viewpoint of preventing nozzle clogging. The coarse particles are removed by, for example, filtering the ink obtained by mixing the above components using a filter such as a membrane filter or a mesh filter, and removing particles of preferably 10 μm or more, more preferably 5 μm or more. Done.

<Example>
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In addition, the numerical value in a table | surface shows weight%.

(1) Preparation of pigment dispersion Pigment 25.0% by weight
Styrene-acrylic acid copolymer (dispersion resin) 5.0% by weight
A pigment, a styrene-acrylic acid copolymer (dispersant resin: acid value 100, average molecular weight 10,000), potassium hydroxide and water were mixed and dispersed with zirconia beads in a sand mill (manufactured by Yasukawa Seisakusho). . Thereafter, the beads were removed, and coarse particles were removed by centrifugation and filtration through a filter to obtain a pigment dispersion.
Depending on the pigment used, the pigment dispersion is referred to as follows.
Pigment dispersion BK: (Pigment) Carbon black

(2) Preparation of ink composition The obtained dispersion and the components shown in Table 1 below were mixed and stirred at 25 ° C for 60 minutes. The mixed solution was filtered through a 5 μm membrane filter to obtain ink compositions of Examples 1 to 4 and Comparative Example 1.

  BYK347 (manufactured by Big Chemie Japan) is a compound included in the formula (1). BYK348 (manufactured by Big Chemie Japan) is a compound included in the formula (2).

  The compositions of Examples 1 to 4 and Comparative Example 1 are summarized in Table 1.

(3) Evaluation test About each ink composition of this invention, it filled in inkjet printer EM930C (made by Seiko Epson Corporation), the following evaluation tests were done, and the result obtained is shown in Table 2.

<Evaluation 1: Printing unevenness>
As a recording medium, characters and solid printing were performed in a plain paper-clean mode on three types of papers of Xerox 4024 (Xerox), Xerox P (Xerox), and Hanmer Mill Copy Plus (Hanmer Mill). The print density of the printed part D. Ten points were randomly measured with a value measuring instrument (SPM-50, manufactured by GRETAG), and the result was determined according to the following criteria.
Determination A: The difference in OD values of 10 points is less than 0.05.
Determination B: The difference in 10-point OD value is 0.05 or more and less than 0.1.

<Evaluation 2: Edge sharpness>
The printed matter obtained in Evaluation 1 was visually observed, and bleeding was evaluated according to the following criteria.
Judgment A: No bleeding occurred on all sheets.
Determination B: Slight bleeding occurred only on at least one type of paper.

<Evaluation 3: Print density (OD value)>
After leaving the three types of printed matter obtained in Evaluation 1 for 1 hour in a general environment, the print density of the solid print portion was determined as O.D. D. It measured with the value measuring device (The product made by GRETAG, SPM-50). The result was determined according to the following criteria.
Determination A: O.I. D. When the value is 1.3 or more Determination B: O.I. D. When the value is 1.2 or more and less than 1.3

<Evaluation 4: Continuous printing stability>
Continuous printing was performed at room temperature (25 ° C.), and the presence or absence of printing defects such as missing dots and ink scattering was observed. The results were evaluated according to the following criteria.
Judgment A: The occurrence of missing dots or ink scattering is 10 times or less after 72 hours.
Determination B: Within 48 to 72 hours, dot missing or ink scattering occurred 10 times.

  The test results of Examples 1 to 4 and Comparative Example 1 are summarized in Table 2.

  As shown in Table 2, the inks of Examples 1 to 6 of the present invention have good print quality on plain paper, particularly high O.D. D. Value and edge sharpness can be obtained, and furthermore, it is possible to provide a suitable pigment ink composition that ensures ejection stability and has very little printing unevenness.

The aqueous ink composition of the present invention has high printing quality and high ejection stability, and is particularly suitable for use as an ink for inkjet recording.

Claims (7)

An ink composition comprising at least a resin-dispersed pigment, a compound represented by the following formula (1), a compound represented by the following formula (2), and water.

  The ink composition according to claim 1, further comprising 1,2-hexanediol.   The ink composition according to claim 1, comprising 0.03 to 1% by weight of the compound of the formula (1).   The ink composition according to any one of claims 1 to 3, comprising 0.05 to 2% by weight of the compound of the formula (2).   The ink composition according to any one of claims 2 to 4, comprising 0.5 to 10% by weight of the 1,2-hexanediol.   The ink composition according to any one of claims 1 to 5, wherein the pigment is dispersed by a polymer compound having a carboxyl group. The ink composition according to claim 6, wherein the polymer compound having a carboxyl group is a styrene-acrylic acid resin.