JP2005263970A - Ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink composition that actualizes excellent printing qualities on plain paper in an inkjet recording method, especially secures high print density and edge sharpness and has extremely slight printing unevenness. <P>SOLUTION: The ink composition comprises at least resin-dispersion type pigment, a compound represented by formula (1) (R1-R7 are each independently a 1-6C alkyl group; j and k are each independently an integer of ≥1; EO is an ethyleneoxy group; PO is a propyleneoxy group; l, m and n are each an integer of ≥0 and m+n is an integer of ≥1; EO and PO each may be random or block irrespective of their order in [ ]), a compound represented by formula (2) (m+n is ≥0 and ≤50; R1, R2, R3 and R4 are each independently an alkyl group (preferably a 1-6C alkyl group)), 1,2-octanediol and water. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 that realizes an (optical density) value and edge sharpness and is suitable for ink jet recording with extremely little printing unevenness.

  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. Various properties are required for inks used in such ink jet recording. For example, the storage stability, ejection stability, and scratch resistance of the printed material are good. In particular, 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. An ink in which a pigment is dispersed in an aqueous medium 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.

  The dye penetrates and fixes on a recording medium such as paper. On the other hand, the pigment particles basically do not penetrate into a recording medium such as paper, and remain on the recording medium to develop color. Therefore, the pigment-based ink composition is easily affected by the surface state of the recording medium. The so-called plain paper has unevenness in fixing of the pigment due to the blanket of paper fiber, and it is difficult to realize a good quality image. Therefore, a so-called special paper having a smooth and homogeneous recording medium surface is prepared, and a high quality image is realized by printing the pigment ink composition on the special paper.

  However, there is still a demand for realizing a high quality image using a pigment-based ink composition on plain paper which is inexpensive and widely spread.

  For example, an aqueous pigment ink in which a pigment is dispersed with a surfactant or a polymer dispersant has been proposed. With these conventional inks, the color development is inferior on plain paper, the line width is small, and printing unevenness is conspicuous. Therefore, various additives have been studied for these improvements. For example, a silicon-based modified polysiloxane compound is known as one of surfactants as an additive. Several ink compositions containing this compound are also known. For example, an ink composition for lithographic printing containing an organo-modified polysiloxane (see, for example, Patent Document 1) is disclosed. In addition, an ink composition containing a modified polysiloxane as an antifoaming agent (for example, see Patent Document 2) is disclosed. In addition, an ink composition for ink jet recording comprising a modified polysiloxane having a specific structure (for example, see Patent Documents 3 and 4) is disclosed. Furthermore, a dye-based ink composition containing a diol-based solvent as one of solvents as an additive (for example, see Patent Document 5) is disclosed.

  However, when examining the ink composition for inkjet, the print quality, particularly O.D. D. The value (optical density), edge sharpness, and print unevenness are not always effective with any type of surfactant or solvent, but are greatly influenced by the structure and amount of addition. Selection and combination of effective additives It was difficult.

JP 59-66475 A JP-A-60-173068 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 suitable pigment ink composition that realizes value and edge sharpness and has very little printing unevenness.

  According to the ink composition comprising a silicon surfactant having a specific structure, an acetylene glycol surfactant having a specific structure, and 1,2-octanediol, a resin dispersion pigment dispersion is obtained by the present inventors. Realization of good print quality in recording, that is, high O.D. D. We obtained knowledge that (optical density) value and edge sharpness were realized and high print quality with extremely little print unevenness could be secured.

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

  According to the present invention, good print quality, particularly high O.D. D. Value and edge sharpness are obtained, 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 formula (1), a compound represented by formula (2), and 1,2-octanediol. It contains. 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), R1 to R7 independently represent a C1-6 alkyl group, preferably a methyl group. j and k independently represent an integer of 1 or more, and more preferably 1 or 2. It is preferable that j = k. L, m, and n represent an integer of 0 or more, provided that m + n represents an integer of 1 or more. Preferably m + n is 1-4.

  Although the addition amount of the compound of Formula (1) may be determined suitably, 0.03-0.5 weight% is preferable, More preferably, it is about 0.05-0.2 weight%.

  The compound of formula (1) is commercially available and can be used. For example, silicon surfactants BYK-345, 347, and 348 are available from Big Chemie Japan Co., Ltd.

  The ink composition according to the present invention comprises the compound of the above formula (2). A preferred specific example of the acetylene glycol surfactant used in the present invention is Surfynol 104 (trade name, manufactured by Nisshin Chemical Co., Ltd.).

  The amount of the compound of formula (2) may be appropriately determined, but is preferably in the range of about 0.05 to 1% by weight, more preferably about 0.1 to 0.5% by weight with respect to the ink composition. It is a range.

  The ink composition according to the present invention comprises 1,2-octanediol. The amount of 1,2-octanediol added may be appropriately determined, but is preferably about 0.5 to 5% by weight, more preferably about 1 to 3% by weight.

  Regarding the compound of the above formula (1), the compound of formula (2), and 1,2-octanediol, if the addition amount is too small, the improvement improvement effect on the printing quality does not appear, and if too much, the reliability is adversely affected The addition amount is a preferable addition range.

  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 that can be used in the present invention is preferably a low-boiling organic solvent. Examples thereof include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, and sec-butanol. , Tert-butanol, iso-butanol, n-pentanol and the like. 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. 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). Surfynol 104PG50 (manufactured by Nissin Chemical Co., Ltd.) contains 50% of the 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. If the value is less than 1.3

  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 4 of the present invention have good print quality on plain paper, particularly high O.D. D. Value and edge sharpness can be obtained, and a suitable pigment ink composition with very little printing unevenness can be provided.

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

Claims (8)

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), 1,2-octanediol, and water. .

  The ink composition according to claim 1, wherein the compound of the formula (1) satisfies j = k.   In the compound of the formula (1), R1 to R7 all represent a methyl group, j represents 1, k represents 1, l represents 1, m represents an integer of 1 or more, and n represents 0. The ink composition according to claim 1, which represents   The ink composition according to any one of claims 1 to 3, comprising 0.03 to 0.5% by weight of the compound of the formula (1).   The ink composition according to any one of claims 1 to 4, comprising 0.05 to 1% by weight of the compound of the formula (2).   The ink composition according to any one of claims 1 to 5, comprising 0.5 to 5% by weight of the 1,2-octanediol.   The ink composition according to claim 1, wherein the pigment is dispersed by a polymer compound having a carboxyl group. The ink composition according to claim 7, wherein the polymer compound having a carboxyl group is a styrene-acrylic acid resin.