CN100537678C - Ink composition for inkjet recording - Google Patents

Abstract

The present invention provides an ink composition comprising at least one pigment and a water-soluble solvent, wherein the composition includes 0.05-0.5% by weight of an alkyl alcohol having 4-6 carbon atoms.

Description

Ink composition for inkjet recording

technical field

The present invention relates to ink compositions. In particular, the present invention relates to an ink composition suitable for an inkjet recording method, and an ink composition in which printing failure due to generation of fine air bubbles does not occur.

Background technique

The inkjet recording method is a recording method in which ink droplets are ejected through minute nozzles to print on a recording medium such as paper. According to this inkjet recording method, high image quality recording can be obtained by using a relatively inexpensive recording device, and thus this recording method has become widely popular in output devices for personal computers. In particular, inkjet printers capable of making photographic image quality equivalent to silver halide photographic image quality have been realized recently, and properties (water resistance, light resistance, and gas resistance) of maintaining printed matter have also been greatly improved. Consequently, their use as output devices for digital cameras has expanded to serve as a replacement for silver halide photographs.

In order to achieve photographic image quality and maintain performance equivalent to those of silver halide photographs, improvements in coloring materials in inks and additives such as resins added to inks have become important. In some inks used in inkjet printers recently, pigments having excellent weather resistance are used as coloring materials, and resins or the like are added to improve the abrasion resistance of printing media. Generally speaking, the ink used in inkjet printers is water-based ink. When using a pigment as a coloring material, since the pigment is insoluble in water, it is necessary to use a method of chemically treating the surface of the pigment, introducing a functional group thereon, and dispersing the pigment in water, or using a method of dispersing the pigment together with the dispersion resin to be used.

Further, when the pigment is used as the coloring material of the water-based ink, the ratio of the added resin (such as resin emulsion) increases, and the thickener, water-soluble solvent (hereinafter also referred to as water-soluble organic solvent) to be added to the ink And the choice of additives has also become particularly important.

In aqueous ink compositions, water, water-soluble materials and hydrophilic materials must be used as raw materials to be used. However, these raw materials, namely thickeners, water-soluble solvents, additives, and the like, enhance the foaming ability and foam stability of the ink composition, and the bubbles remain for a long time without disappearing, which easily causes printing failure . In particular, polyether-modified silicone-based surfactants or polyester-modified silicone-based surfactants greatly enhance foaming ability. Furthermore, glycerol and sugars, as well as water-miscible solvents, are known to act as thickeners to undesirably increase foam stability.

In addition, gases such as nitrogen and oxygen are more soluble in water than in organic solvents, so prolonged storage, changes in air pressure, or the presence of nuclei can produce fine bubbles. Bubbles generated in the ink composition flow at the recording head, which causes printing failures such as ink trajectory deviation, scattering, nozzle clogging, and nozzle thinning.

For this problem, as described in the following patent documents 1-3, it is proposed to add a silicone-based antifoaming agent, a polyalkylene oxide-based antifoaming agent, or a polyether-based antifoaming agent to reduce foaming. capacity and foam stability. However, this alone is not sufficient for polyether-based defoamers or polyester-based defoamers with very high surface activity.

Therefore, it is conceivable to add a material having the property of removing air bubbles, that is, a material slightly soluble in water, which removes foam by destroying the liquid film constituting the foam (defoaming property).

For example, Patent Document 4 below discloses an inkjet ink composition consisting of a microemulsion comprising an aqueous pigment dispersion, at least one water-insoluble inkjet ink composition, and a pigment-based inkjet ink composition. An organic compound, at least one hydrophilic amphiphilic material, and water; wherein the hydrophilic amphiphilic material is present in the microemulsion in an amount sufficient to dissolve a water-insoluble organic compound. Specific examples of the water-insoluble organic compound used in this inkjet ink composition include a large number of organic compounds, and alkyl alcohols having 5 or more carbon atoms may be mentioned as examples.

Patent Document 1: JP-A-2002-322394

Patent Document 2: JP-A-2003-105236

Patent Document 3: JP-A-2004-292707

Patent Document 4: JP-A-10-1627

However, when water-insoluble components increase in the aqueous ink composition, the amount of amphiphilic solvent used to dissolve them also increases, and for reasons other than bubble generation, precipitation or coagulation of insoluble components occurs. The ejection state of the ink head deteriorates, which causes ink trajectory deviation, nozzle clogging, ink scattering, and the like in some cases.

In Patent Document 4, the amount of water-insoluble components added is 1% by weight or more, so that the deterioration of the ink ejection state depends on the solvent type, resulting in easy occurrence of track deviation, scattering, nozzle clogging, nozzle thinning and Similar flaws. Specifically, these phenomena become conspicuous when the inkjet recording head is filled with ink and left for a long period of time without printing at all.

Contents of the invention

An object of the present invention is to provide an aqueous pigment ink composition for realizing high-reliability inkjet recording, in which the ejection state of the ink does not deteriorate to cause ink track deviation, scattering, nozzle clogging, nozzle thinning and the like Defects occur because even when fine air bubbles are generated therein when the ink is left for a long period of time without printing, these bubbles disappear quickly.

Other objects and effects of the present invention will become apparent from the following description.

The present inventors have studied reliability including printing quality and printing characteristics, such as ejection of aqueous pigment ink compositions for inkjet recording. As a result, the inventors have found an ink composition that ensures print quality and maintains a good ejection state because even when fine air bubbles are generated, especially by filling an ink cartridge for a general inkjet printer with it and allowing it to stand for a long period of time When it is in a non-printing state and thus generates fine air bubbles, these bubbles will also disappear quickly. The present invention is based on this discovery.

According to the present invention, the above object can be achieved by employing the following composition.

That is, the present invention is as follows:

(1) An ink composition comprising at least one pigment and a water-soluble solvent, wherein the composition comprises an alkyl alcohol having 4-6 carbon atoms in an amount of 0.05-0.5% by weight;

(2) The ink composition described in (1), wherein the water-soluble solvent is 1,2-alkanediol or glycerol;

(3) The ink composition described in (2), wherein the 1,2-alkanediol is 1,2-hexanediol;

(4) The ink composition described in any one of (1)-(3), wherein the alkyl alcohol having 4 to 6 carbon atoms is an n-alkyl alcohol;

(5) The ink composition described in (4), wherein the n-alkyl alcohol is 1-hexanol;

(6) The ink composition described in any one of (1)-(5), wherein the composition further comprises a surfactant;

(7) The ink composition described in (6), wherein the surfactant is a silicone-based surfactant;

(8) The ink composition described in (7), wherein the silicone-based surfactant is a polyether-modified silicone-based surfactant;

(9) The ink composition described in (8), wherein the polyether-modified silicone-based surfactant has the following structure:

Wherein R ¹ -R ⁹ independently represent C _1-6 alkyl, j and k independently represent an integer of 1 or greater, EO represents ethyleneoxy, PO represents propyleneoxy, and m and n represent 0 or an integer greater than 0, provided that m+n is an integer of 1 or greater, and the order of EO and PO in square brackets is not limited and EO and PO can be randomly arranged or can form a block;

(10) The ink composition described in any one of (1)-(9), wherein the pigment is a resin-dispersed pigment; and

(11) The ink composition described in any one of (1)-(10), wherein the composition further contains sugar alcohol.

By constituting the above-mentioned ink composition, the print quality is ensured and the ejection state is kept good because even when fine air bubbles are generated, especially by filling an ink cartridge for a general inkjet printer with it and leaving it for a long period of time without When the state of printing thus produces fine air bubbles, these bubbles also disappear quickly.

The ink composition for inkjet recording of the present invention will be described in detail below.

The ink composition of the present invention contains a pigment as a colorant. Any inorganic and organic pigments can be used. Inorganic pigments include carbon black prepared by known methods such as contact method, furnace method and heat treatment method, in addition to titanium oxides and iron oxides. In addition, as organic pigments, azo pigments (including azo lakes, insoluble azo pigments, concentrated azo pigments, chelated azo pigments and the like), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinolphthalone pigments and the like), dye-type chelated pigments (for example, basic dye type chelate pigments, acid dye type chelate pigments and the like), nitro pigments, nitroso pigments, nigrosine and the like.

As carbon black, specific examples of pigments include, No.2300, No.900, MCF 88, No.33, No.40, No.45, No.52, MA7, MA8, MA100, No. 2200B and the like; Raven 5750, Raven5250, Raven 5000, Raven 3500, Raven 1255, Raven 700 and the like produced by Columbian Carbon Co., Ltd.; Regal 400R, Regal 330R, Regal 660R, Mogul L, Mogul700 produced by Cabot Corporation , Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 and the like; and Color Black FW1, Color Black FW2, Color Black FW2V, Color Black produced by Degussa AG Black FW18, Pigmented Carbon Black FW200, Pigmented Carbon Black S150, Pigmented Carbon Black S160, Pigmented Carbon Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black4A, Special Black 4 and analog.

Pigment examples for yellow ink include C.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.

Pigment examples for magenta inks include C.I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 168, 184 , 202, 209 and the like.

Examples of pigments for cyan ink include C.I. Pigment Blue 1, 2, 3, 15:3, 15:4, 16, 22 and 60.

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

Although the amount of pigment added can be appropriately determined, it is preferably within a range of 0.1-20% by weight of the ink composition, more preferably within a range of 1-10% by weight of the ink composition.

In the present invention, it is preferable that the pigment is added to the ink composition in the form of a pigment dispersion, and in the pigment dispersion, the pigment is dispersed with a dispersant. Dispersants include polymer dispersants and surfactants.

Examples of preferable polymer dispersants include natural polymers, and specific examples thereof include proteins such as glue, gelatin, casein, and albumin; natural rubbers such as gum arabic and tragacanth; glucosides such as saponins glycosides; alginic acid and alginic acid derivatives such as propylene glycol alginate, triethanolamine alginate and ammonium alginate; cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and ethyl cellulose Hydroxyethyl cellulose, etc.

Examples of preferred polymer dispersants include synthetic polymers, specific examples of which include polyvinyl alcohol; polyvinylpyrrolidone; acrylic resins such as polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium salt of potassium acrylate-acrylonitrile copolymer , vinyl acetate-acrylate copolymers and acrylic acid-alkyl acrylate copolymers; styrene-acrylic resins, such as styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid Alkyl ester copolymer, styrene-alpha-methylstyrene-acrylic acid copolymer and styrene-alpha-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymer; styrene-maleic acid copolymer; styrene - maleic anhydride copolymers; vinylnaphthalene-acrylic acid copolymers; vinylnaphthalene-maleic acid copolymers; vinyl acetate-based copolymers such as vinyl acetate-ethylene copolymers, vinyl acetate-fatty acid vinyl ethylene ester copolymers, vinyl acetate-maleate copolymers, vinyl acetate-crotonic acid copolymers, and vinyl acetate-acrylic acid copolymers; and salts thereof. Particularly preferred, of course, are carboxyl group-containing (preferably in the form of salts) copolymers (such as the aforementioned styrene-acrylic resins, styrene-maleic acid, styrene-maleic anhydride, vinylnaphthalene-acrylic acid copolymers, vinylnaphthalene -maleic acid copolymers and vinyl acetate-acrylic acid copolymers), copolymers of hydrophobic group-containing monomers and hydrophilic group-containing monomers and polymers containing monomers having both hydrophobic groups and hydrophilic groups. Examples of the above salts include those having diethylamine, ammonia, ethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, triethanolamine, diethanolamine, Salts of aminomethylpropanol, morpholine and similar. The weight average molecular weight of these copolymers is preferably from 3,000 to 30,000, more preferably from 5,000 to 15,000.

In addition, examples of surfactants preferable as dispersants include anionic surfactants such as fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfate ester salts, higher alkyl sulfonates, condensation of higher fatty acids and amino acids salts, sulfosuccinates, naphthenates, liquid fatty oil sulfates and alkylallyl sulfonates; cationic surfactants such as fatty acid amine salts, quaternary ammonium salts, sulfonium salts and phosphonium salts; non- Ionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyethylene oxide sorbitan alkyl esters; and the like. Those skilled in the art can understand that when the above-mentioned surfactant is added to the ink composition, it also functions as a surfactant.

In addition, the ink composition of the present invention further contains a water-soluble solvent. Although not particularly limited, the water-soluble solvent is preferably 1,2-alkanediol and/or glycerin. Specific examples of 1,2-alkanediol include 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-Heptanediol, 1,2-octanediol and the like. More preferred are 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol and 1,2-hexanediol, most preferably 1,2-hexanediol. Although the amount of 1,2-alkanediol added can be appropriately determined, it is preferably from about 1% to about 15% by weight, more preferably from about 2% to about 10% by weight.

In addition, a low-boiling-point organic solvent is preferably used as the water-soluble solvent. Examples of low-boiling organic solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, t-butanol, isobutanol, n-pentanol, and the like. Specifically, monohydric alcohols are preferred. The low-boiling point organic solvent has the effect of shortening the time required for ink to dry. The low-boiling point organic solvent is preferably added in an amount of about 5% by weight or less, more preferably about 2% by weight or less, based on the amount of the ink composition.

The ink composition of the present invention may further contain a humectant containing a high boiling point organic solvent. Examples of preferred high-boiling organic solvents include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, Thioglycol, hexanediol, glycerol, trimethylolethane and trimethylolpropane; urea; 2-pyrrolidone; N-methyl-2-pyrrolidone; 1,3-di Methyl-2-imidazolinone and the like. These solvents may be used alone or in combination of two or more. Among them, glycerol, triethylene glycol monobutyl ether, 2-pyrrolidone, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, diethylene glycol monobutyl ether, and urea are preferable. They are added in an amount preferably in the range of about 1% to about 20% by weight, more preferably in the range of about 5% to about 10% by weight, based on the amount of the ink composition.

In addition, the ink composition of the present invention contains 0.05-0.5% by weight of an alkyl alcohol having 4-6 carbon atoms. According to a preferred embodiment of the present invention, the alkyl alcohol having 4-6 carbon atoms is preferably an n-alkyl alcohol (primary alcohol), more preferably 1-butanol, 1-pentanol or 1-hexanol. According to the research results of the present inventors, it is clear that adding an alkyl alcohol within the above range to the ink composition can effectively remove the fine air bubbles in the ink due to long-term storage, so that the printing stability is further improved.

Furthermore, the combination of 1,2-hexanediol and n-hexanediol can achieve the best above-mentioned effects, although the reason for this is not known exactly.

In the ink composition of the present invention, the addition amount of the alkyl alcohol having 4-6 carbon atoms is in the range of 0.05-0.5% by weight. When the addition amount of the alkyl alcohol having 4 to 6 carbon atoms is less than 0.05% by weight, the defoaming effect of the above ink when left for a long period of time is reduced. When the added amount of the alkyl alcohol exceeds 0.5% by weight, the dispersion becomes unstable and the pigment particles aggregate, thus causing a disadvantage in that the color of the ink changes in some cases resulting in a color change of the printed item.

According to a preferred embodiment of the present invention, it is preferred that the ink composition of the present invention comprises a compound represented by the following formula (I) as a surfactant:

In formula (I), R ¹ -R ⁹ each independently represent a C _1-6 alkyl group, preferably a methyl group. j and k each independently represent an integer of 1 or greater, preferably 1 or 2. m and n each represent an integer of 0 or greater, provided that m+n is an integer of 1 or greater, preferably 2-4.

According to a preferred embodiment of the present invention, compounds satisfying j=k+1 are preferred as compounds of formula (I). Further, according to another preferred embodiment of the present invention, it is preferred that all R1-R9 independently represent a methyl group, j represents 2, k represents 1, 1 represents 1, m represents 1 or an integer greater than 1 and n represents 0 compounds as a compound of formula (I).

Although the addition amount of the compound of formula (I) can be appropriately determined, it is preferably 0.03-3% by weight, more preferably about 0.1-about 2% by weight, most preferably about 0.3-about 1% by weight .

Compounds of formula (I) are commercially available and it is possible to utilize them. For example, silicone-based surfactants BYK-345, BYK-346 and BYK-348 are available from Byk-Chemie Japan K.K.

The ink composition of the present invention further contains water. As the water used, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, or distilled water, or ultrapure water can be used. Further, the use of water sterilized by ultraviolet radiation, the addition of hydrogen peroxide or the like is suitable because it prevents the generation of mold or bacteria when the ink composition is stored for a long period of time.

Furthermore, the ink composition of the present invention may also contain a penetrating agent. Specific examples of penetrants include glycol ether and/or acetylene glycol surfactants.

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 monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol mono-n-butyl ether, ethyl Diol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-tert-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol mono Methyl ether, propylene glycol monoethyl ether, propylene glycol mono-tert-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl 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-isopropyl ether and the like. These may be used alone or as a mixture of two or more of them. The added amount of the glycol ether is preferably within a range of 1 to 20% by weight, more preferably within a range of 2 to 15% by weight, based on the amount of the ink composition.

According to a preferred embodiment of the invention, preference is given to using alkyl ethers of polyhydric alcohols. Specifically, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and triethylene glycol monobutyl ether are preferably used. Methyl ether, triethylene glycol monoethyl ether, or triethylene glycol monobutyl ether. More preferred is triethylene glycol monobutyl ether. Although the addition amount of the alkyl ether of polyhydric alcohol can be properly determined, it is preferably about 1% to about 10% by weight, more preferably about 3% to about 5% by weight.

Sugars may also be added to the ink composition of the present invention. Specific examples of preferred carbohydrates include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and other polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldose acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, xylitol and the like. The term "polysaccharide" as used herein means sugars in a broad sense and should be understood to include substances widely present in nature, such as alginic acid, α-cyclodextrin and cellulose. Derivatives of these sugars include reducing sugars of the above-mentioned sugars (for example, sugar alcohols represented by the general formula HOCH2(CHOH)nCH2OH, wherein n represents an integer of 2-5), oxidized sugars (for example, aldonic acid and furfural acids), amino acids, thiosugars and the like. Specifically, sugar alcohols are preferred, and specific examples thereof include maltitol, sorbitol, and the like.

These sugars are preferably added in an amount of about 1 to about 20% by weight, more preferably about 3 to about 10% by weight, based on the amount of the ink composition.

Nozzle anti-clogging agents, preservatives, antioxidants, conductivity regulators, pH regulators, viscosity regulators, surface tension regulators, oxygen absorbers, or the like may be further added to the ink composition of the present invention.

Examples of preservatives and biocides include sodium benzoate, sodium pentachlorophenate, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzothiazolin-3-one (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2 and Proxel TN manufactured by Avecia) and the like.

Further, examples of pH regulators, solubilizers, or antioxidants include: amines, such as diethanolamine, triethanolamine, propanolamine, and morpholine, and their modified products; inorganic salts, such as potassium hydroxide, sodium hydroxide and lithium hydroxide; ammonium hydroxide; quaternary ammonium hydroxides such as tetramethylammonium; carbonates such as potassium carbonate, sodium carbonate and lithium carbonate; phosphates; N-methyl-2-pyrrolidone; urea compounds such as Urea, thiourea, and tetramethylurea; allophanates, such as allophanate and methylallophanate; biurets, such as biuret, dimethylbiuret, and tetramethylurea and L-ascorbic acid and its salts.

Example

The present invention will be illustrated in more detail with reference to the following examples, but the invention should not be construed as being limited thereto.

Ink composition preparation example 1

The pigment, dispersant and ion-exchanged water were mixed and stirred to form a mixture, which was dispersed in a sand mill (manufactured by Yasukawa Seisakusho) with glass beads (1.7 mm in size, 1.5 times the weight of the mixture) for 2 hours. Thereafter, the beads were removed with a separator to obtain a pigment dispersion.

Then, various additives other than the pigment and the dispersant among the following compounding components were mixed to prepare a completely dissolved ink solvent.

Under stirring, the above-mentioned pigment dispersion was gradually added dropwise into the ink solvent, and after the dropwise addition was completed, mixing and stirring was carried out at room temperature for 30 minutes. The mixed solution was filtered with a 5 micron membrane filter to obtain an ink composition. The composition of the obtained ink is shown below.

Example 1

C.I. Pigment Red 122 (pigment) 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc., sugar alcohol) 8.0% by weight

BYK 348 (Byk-Chemie Japan K.K., polyether-modified silicone-based surfactant) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Butanol 0.2% by weight

Ion-exchanged water Balance

Example 2

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

2-Butanol 0.2% by weight

Ion-exchanged water Balance

Example 3

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Pentanol 0.2% by weight

Ion-exchanged water Balance

Example 4

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

2-Pentanol 0.2% by weight

Ion-exchanged water Balance

Example 5

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

3-Pentanol 0.2% by weight

Ion-exchanged water Balance

Example 6

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Hexanol 0.2% by weight

Ion-exchanged water Balance

Example 7

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348(Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Hexanol 0.05% by weight

Ion-exchanged water Balance

Example 8

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Hexanol 0.10% by weight

Ion-exchanged water Balance

Example 9

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Hexanol 0.20% by weight

Ion-exchanged water Balance

Example 10

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Hexanol 0.50% by weight

Ion-exchanged water Balance

Comparative Example 1

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

Ethanol 0.2% by weight

Ion-exchanged water Balance

Comparative Example 2

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-propanol 0.2% by weight

Ion-exchanged water Balance

Comparative Example 3

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

2-propanol 0.2% by weight

Ion-exchanged water Balance

Comparative Example 4

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

CH-200 (Dow Coming Toray Co., Ltd., silicone-based defoamer) 0.05% by weight

Ion-exchanged water Balance

Comparative Example 5

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

TSA 730 (GE Toshiba Silicones Co., Ltd., silicone-based antifoaming agent) 0.05% by weight

Ion-exchanged water Balance

Comparative Example 6

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

PF751 (Asahi Glass Co., Ltd., polyether polyol-based defoamer) 0.05% by weight

Ion-exchanged water Balance

Comparative Example 7

C.I. Pigment Red 1221.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

PF 752 (Asahi Glass Co., Ltd., polyether polyol-based defoamer) 0.05% by weight

Ion-exchanged water Balance

Comparative Example 8

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

PF753 (Asahi Glass Co., Ltd., polyether polyol-based defoamer) 0.05% by weight

Ion exchanged water residual weight

Comparative Example 9

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

Ion-exchanged water Balance

Comparative Example 10

C.I. Pigment Red 122 1.0% by weight

Styrene-acrylic acid copolymer ammonium salt (dispersant, average molecular weight: 10,000) 1.0% by weight

Glycerol 20.0% by weight

HS-500 (Hayashibara Shoji Inc.) 8.0% by weight

BYK348 (Byk-Chemie Japan K.K.) 0.5% by weight

1,2-Hexanediol 5.0% by weight

Triethanolamine 1.0% by weight

1-Hexanol 0.01% by weight

Ion-exchanged water Balance

Ink composition preparation example 2

Pigment, styrene-acrylic copolymer resin (acid value: 100, average molecular weight: 10,000), potassium hydroxide, and water were mixed and dispersed in a sand mill (manufactured by Yasukawa Seisakusho) with zirconia beads. Thereafter, the beads were removed, followed by centrifugation with a filter to remove coarse particles. Thus, a pigment dispersion is obtained.

An aqueous organic solvent, a surfactant, water and the like were added to the above-mentioned pigment dispersion, followed by stirring at 25°C for 60 minutes. The mixed solution was filtered with a 5 micron membrane filter to obtain an ink composition. The obtained ink compositions are shown below.

Example 11

C.I. Pigment Blue 15:3 5.0% by weight

Styrene-acrylic acid copolymer (acid value: 100, average molecular weight: 10,000) 2.0% by weight

1,2-Hexanediol 5.0% by weight

Glycerol 10% by weight

HS-500 (Hayashibara Shoji Inc., reduced maltose) 10% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

Triethanolamine 1.0% by weight

n-Butanol 0.05% by weight

ultrapure water balance

Example 12

C.I. Pigment Red 122 4.0% by weight

Styrene-acrylic acid copolymer (acid value: 100, average molecular weight: 10,000) 1.5% by weight

1,2-Hexanediol 5.0% by weight

Glycerol 10% by weight

HS-500 (Hayashibara Shoji Inc., reduced maltose) 10% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

Triethanolamine 1.0% by weight

n-Hexane 0.5% by weight

ultrapure water balance

Example 13

C.I. Pigment Blue 15:3 5.0% by weight

Styrene-acrylic acid copolymer (acid value: 100, average molecular weight: 10,000) 2.0% by weight

1,2-Hexanediol 5.0% by weight

Glycerol 10% by weight

HS-500 (Hayashibara Shoji Inc., reduced maltose) 10% by weight

BYK 348 (Byk-Chemie Japan K.K.) 0.5% by weight

Triethanolamine 1.0% by weight

2-Pentanol 0.05% by weight

ultrapure water balance

Comparative Example 11

C.I. Pigment Blue 15:3 5.0% by weight

Styrene-acrylic acid copolymer (acid value: 100, average molecular weight: 10,000) 2.0% by weight

Glycerol 10% by weight

Olfin E1010 (Shin-Etsu Chemical Co., Ltd.) 1.0% by weight

Triethanolamine 1.0% by weight

Ethanol 1.0% by weight

ultrapure water balance

Comparative Example 12

C.I. Pigment Red 122 4.0% by weight

Styrene-acrylic acid copolymer (acid value: 100, average molecular weight: 10,000) 1.5% by weight

Diethylene glycol monobutyl ether 5.0% by weight

Glycerol 10% by weight

HS-300 (Hayashibara Shoji Inc., reduced maltose) 10% by weight

Olfin E1010 (Shin-Etsu Chemical Co., Ltd.) 1.0% by weight

Triethanolamine 1.0% by weight

n-Hexanol 0.04% by weight

ultrapure water balance

Comparative Example 13

C.I. Pigment Red 122 4.0% by weight

Styrene-acrylic acid copolymer (acid value: 100, average molecular weight: 10,000) 1.5% by weight

1,2-Hexanediol 5.0% by weight

Glycerol 10% by weight

Olfin E1010 (Shin-Etsu Chemical Co., Ltd.) 1.0% by weight

Triethanolamine 1.0% by weight

n-Hexanol 1.0% by weight

ultrapure water balance

Defoaming performance test

30 grams of the ink compositions described in Examples 1-10 and Comparative Examples 1-10 were respectively weighed into sample bottles with a diameter (inner diameter) of 37 mm, a height of 100 mm and a volume of 110 ml. Cap the bottle and shake for 5 seconds to create a lather. Then, the height of foam produced was measured. Thereafter, the sample bottle was sanded in the same manner, and the height of the foam was measured again after a predetermined period of time.

Evaluation 1: Defoaming performance 1

The evaluation indices of Examples 1-6 and Comparative Examples 1-8 are as follows:

A: Foam height ≤ 10 mm after foaming operation for 60 minutes, and foam height ≤ 6 mm after 120 minutes.

B: Foam height ≤ 15 mm after foaming operation for 60 minutes, and foam height ≤ 10 mm after 120 minutes.

C: Foam height ≤ 20 mm after foaming operation for 60 minutes, and foam height ≤ 15 mm after 120 minutes.

D: The foam height is higher than 20 mm after 60 minutes of foaming operation.

The evaluation results of Examples 1-6 and Comparative Examples 1-8 are listed in Table 1.

Table 1

Foam height (mm) after a certain time (minutes) 0 60 120 Defoaming Evaluation 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 25 7 520 5 512 6 514 8 315 10 63 0 0 AAAAAAA Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 25 15 1525 14 1425 12 1025 25 2025 20 2025 20 1525 20 1525 20 15 CCBDDCCC

Evaluation 2: Defoaming Performance 2

The evaluation indices of Examples 7-10 and Comparative Examples 9-10 are as follows:

AAA: Foaming was not observed immediately after the foaming operation.

AA: The immediate height of the foam after the foaming operation is ≤ 10 mm, and the foam height is ≤ 5 mm after 15 minutes, and the foam disappears after 60 minutes.

A: The immediate foam height after foaming operation is ≤15mm, the foam height after 15 minutes is ≤10mm, and the foam height after 60 minutes is ≤6mm.

B: The immediate foam height after the foaming operation is ≤25 mm, the foam height after 15 minutes is ≤20 mm, and the foam height after 60 minutes is ≤15 mm.

C: The immediate height of the foam after the foaming operation is ≤25 mm, the foam height is higher than 20 mm after 15 minutes, and the foam height is higher than 15 mm after 60 minutes.

The evaluation results of Examples 7-10 and Comparative Examples 9-10 are listed in Table 2.

Table 2

Foam height (mm) after a certain time (minutes) 0 15 30 60 Defoaming Evaluation 2 Example 7 Example 8 Example 9 Example 10 15 10 8 67 2 1 03 0 0 00 0 0 0 AAAAAAAAA Comparative Example 9 Comparative Example 10 25 22 20 1625 20 20 12 CB

Evaluation 3: Print Stability

Ink cartridges PM-4000PX for inkjet printers manufactured by Seiko Epson Corporation were filled with the ink compositions described in Examples 11-13 and Comparative Examples 11-13, respectively, and then mounted on the printer. After confirming that all the nozzles could be ejected, the ink cartridge was left in an environment of 40° C. for one month. After this placement, a regular linear pattern is printed on blank paper up to the ink tank ink layer. The evaluation index is as follows:

AA: Ruled lines are not missing and thinning at all.

A: Thinning of the regular line occurs near the ink end of the ink cartridge, but it is restored by washing.

B: Regular line thinning occurred only near the ink end of the ink cartridge, but it could not be recovered even after washing.

C: Missing dots frequently occurred.

Assessment 4: Color Assessment

After being left in an environment of 40°C for one month by the method in Evaluation 3, a monochrome stripe pattern was printed on PM photo paper (manufactured by Seiko Epson Corporation) until the layer for ink in the ink tank. Estimates the maximum color difference in one cartridge based on the color of the first printed page. The evaluation index is as follows:

A: The maximum color difference (ΔE) in one ink cartridge is less than 3.

B: The maximum color difference (ΔE) in one ink cartridge is from 3 to less than 4.

C: The maximum color difference (ΔE) in one ink cartridge is from 4 to less than 5.

D: The maximum color difference (ΔE) in one ink cartridge is 5 or more.

The evaluation results are shown in Table 3 below.

table 3

Evaluation 3 Evaluation 4 Example 11 A A Example 12 AAA A Example 13 A B Comparative Example 11 B C Comparative Example 12 B A Comparative Example 13 A D.

While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.

This application is based on Japanese Patent Application No. 2005-097591 (filed on March 20, 2005) and No. 2005-283024 (filed on September 28, 2005), the contents of which are incorporated herein by reference.

Claims (10)

1. An ink composition comprising at least one pigment and a water-soluble solvent, wherein said composition comprises 0.05 to 0.5% by weight of 1-butanol, 1-pentanol or 1-hexanol of alkyl alcohols. 2. The ink composition of claim 1, wherein the water-soluble solvent is 1,2-alkyl glycol or glycerol. 3. The ink composition of claim 2, wherein the 1,2-alkyl glycol is 1,2-hexanediol. 4. The ink composition of claim 1, wherein the alkyl alcohol is 1-hexanol. 5. The ink composition of claim 1, wherein the composition further comprises a surfactant. 6. The ink composition of claim 5, wherein the surfactant is a silicone-based surfactant. 7. The ink composition of claim 6, wherein the silicone-based surfactant is a polyether-modified silicone-based surfactant. 8. The ink composition of claim 7, wherein the polyether-modified silicone-based surfactant has the structure: Wherein R1-R9 each independently represent C1-6 alkyl, j and k each independently represent an integer of 1 or greater, EO represents an ethylene oxide group, PO represents a propylene oxide group, and m and n Each represents an integer of 0 or greater, provided that m+n is an integer of 1 or greater, and the order of EO and PO in the parentheses is not limiting, and EO and PO can be arranged randomly, or form a block. 9. The ink composition according to claim 1, wherein the pigment is a resin-dispersed pigment. 10. The ink composition of claim 1, wherein the composition further comprises a sugar alcohol.