JP3001125B2 - Inkjet recording liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording liquid suitable for an ink jet system in which liquid droplets are ejected from an orifice of a recording head to perform recording, and more particularly, to an excellent ink characteristic having little sedimentation and liquid separation. It has excellent mechanical properties such as dischargeability, continuous stability, non-clogging property, good drying resistance at the discharge orifice, fixing property,
The present invention relates to an ink jet recording liquid having excellent print characteristics such as print density and print quality.

[0002]

2. Description of the Related Art Conventionally, writing instruments (sign pens, water-based ball pens, etc.) for recording on a recording material such as paper have various dyes and pigments dissolved in water or other organic solvents as ink. Dispersed ones are used. Further, in a so-called ink jet recording method in which ink in a head is ejected from fine nozzles by electrostatic printing force caused by the vibration or heat of a pressure oscillator or high voltage and electrostatic printing force is applied to perform recording, various dyes, Pigments dissolved or dispersed in water or other organic solvents are used.

However, compared to stationery inks such as general felt-tip pens and water-based ball pens, the recording liquid used in the ink jet recording system performs recording by generating ink droplets from extremely fine nozzles. Therefore, more precise conditions are required for many characteristics.

[0004] In other words, the recording liquid for ink-jet recording includes: 1. proper physical properties (viscosity, particle diameter, surface tension, specific conductivity,
Density). 2. It is stable for long-term storage, and solids do not precipitate or do not adhere to the vicinity of the nozzle when not in use for a long time or when printing is suspended.

[0005] 3. The printed image has sufficiently high contrast and sharpness. 4. The printed image has excellent water resistance and fixability. 5. Able to print with contrast without the need for specific fixing process for plain paper. It is necessary to satisfy such conditions.

At present, as ink for ink jet recording,
Basically, an aqueous ink containing a dye, water and a water-miscible organic solvent as a solvent is mainly used, but the physical properties of the recording liquid largely depend on the intrinsic properties of the dye.

Therefore, when ink-jet recording is performed using a recording liquid containing a water-soluble dye, the resulting recorded image is affected by the physical properties of the water-soluble dye, and thus has poor water and light fastness. There was a drawback that it would be inferior. Further, the storage stability of the recording liquid itself containing such a water-soluble dye is not so high.

In the recorded print, the water-soluble dye easily bleeds on the paper, and only a low contrast and unclear image can be obtained. Therefore, recently, an attempt has been made to apply a pigment-based recording liquid to an ink jet recording system in place of such a dye-based ink. This pigment-based recording liquid has an advantage that the light resistance and water resistance of the obtained recorded image are extremely good as compared with the image obtained by the dye-based recording liquid.

[0009]

However, since the pigment is insoluble in the recording liquid medium, a high level of technique is required for finely dispersing it in the recording liquid, and the dispersion stability is maintained for a long period of time. It was very difficult.

Further, when solidified in a recording apparatus, redispersibility is poor, causing clogging of a recording liquid, and increasing reliability.

An object of the present invention is to provide an ink jet recording resin and an ink jet recording ink (hereinafter, referred to as a recording liquid) which do not cause nozzle clogging for a long period of time and maintain good ejection stability. Another object is to provide a safe and low-odor recording solution for the human body.

Still another object of the present invention is to provide a recording liquid which is excellent in print fixability, print density, print quality and the like, and gives clear and contrast images without blur on plain paper.

[0013]

[Means for solving the problems]

The present invention provides an aqueous pigment-dispersed inkjet recording liquid in which the medium is an aqueous medium containing a water-soluble organic solvent, wherein the inkjet recording liquid contains a pigment, an oligomer-emulsifier, an organometallic compound or a silane compound. Things.

Preferably, the oligomer-emulsifier has the following general formula (1) and / or (2)

[0016]

Embedded image

[0017]

Embedded image Here, R ₁ is an alkyl group having 5 to 20 carbon atoms (that is, all groups represented by the general formula C _n H _{2n + 1} ).

R ₂ , R ₃ , R ₅ : hydrogen or an alkyl group having 1 to 5 carbon atoms (general formula C _n H _{2n + 1} ), or a carboxyl group, a carboxylate group or an ammonium base of a carboxylic acid, an amine base, an alkali Metal base or alkaline earth metal base

R ₄ : hydrogen, halogen or an alkyl group having 1 to 4 carbon atoms (general formula C _n H _{2n + 1} ) X: cyano group, —COOCH ₃ group, —OCOCH ₃ or —OCOC ₂ H ₅ Y: hydrogen, ammonium Group, amine base, alkali metal or alkaline earth metal

Wherein b / (a + b) is in the range of 0.45 to 0.95. Examples of the organometallic compound include a titanium compound, a zirconium compound, and an aluminum compound.

Examples of titanium compounds include tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate and tetrastearyl titanate. ,

Hydroxytitanium stearate, isopropoxytitanium stearate, hydroxytitanium oleate, isopropoxytitanium oleate
, Hydroxytitanium soiate, isopropoxytitanium soiate, di-i-propoxybis (acetylacetone) titanate, di-n-butoxy.
Bis (triethanolamine) titanate, dihydroxybis (lactide acid) titanate, tetraoctylene glycol-titanate, di-i-propoxybis (ethyl acetoacetate) titanate,

Isopropyl triisostearoyl titanate, isopropyl tristearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate,
Isopropyl tri (dioctyl phosphate) titanate
Isopropyl tri (lauryl-myristyl) titanate, isopropyl di (lauryl-myristyl) methacryl titanate,

Isopropyl lauryl-myristyl dimethacryl titanate, isopropyl triricinoyl titanate, isopropyl methacryl titanate, isopropyl dimethacryl isostearyl titanate, isopropyl trimethacryl titanate, isopropyl diiso Stearoyl acryl titanate, isopropyl isostearyl diacryl titanate, isopropyl triacryl titanate, isopropyl 4-aminobenzenesulfonyldi (dodecylbenzenesulfonyl) titanate,

Isopropyl di (aminobenzoyl) isostearyl titanate, isopropyl trianthranyl titanate, isopropyl diisostearoyl cumyl phenyl titanate, isopropyl tri-cumyl phenyl titanate, isopropyl tri (Methoxyphenyl) titanate, isopropyl di (2-formylphenyl) isostearoyl titanate, isopropyl tri (2-formylphenyl) titanate,

Dimethacrylethylene titanate, diacrylethylene titanate, 4-aminobenzoylethylene isostearyl titanate, dianthranylethylene titanate, 4-aminobenzenesulfonyl dodecylbenzenesulfonylethylene titanate Tantalate, di- (2-formylphenyl) ethylene titanate, di-cumylphenoxyethylene isostearyl titanate,

Tetraisopropyldi (dilaurylphosphite) titanate, tetraisopropyldi (dioctylphosphite) titanate, tetraoctyloxytitanium di (laurylphosphite), tetra (2,2-diallyloxymethyl-1) -Buteneoxy titanium di (di-
Tridecyl) phosphite, isopropyl tri (N, N-dimethylethylamino) titanate, isopropyl tri (N-ethylamino-ethylamino) titanate, isopropyl tri (dioctyl pyrophosphate) titanate
Isopropyl tri (dibutyl pyrophosphate) titanate, titanium diisostearate oxyacetate, titanium di (dioctyl phosphate) oxyacetate,

Titanium di (dioctyl pyrophosphate)
G) oxyacetate, titanium isostearate methacrylate oxyacetate, titanium di (dibutylpyrophosphate) oxyacetate, titanium dimethacrylate oxyacetate, titanium acrylate isostearate oxyacetate, Titanium diacrylate oxyacetate, titanium 4-aminobenzenesulfonato-dodecylbenzenesulfonate oxyacetate, titanium 4-aminobenzoate isostearate oxyacetate, di (2-formylphenoxy) oxyacetate,

Titanium di (cumylphenolate) oxyacetate, titanium dianthranilate oxyacetate, diisostearoyl ethylene titanate,
Ethylene methacryl isostearyl titanate, di (dioctyl phosphate) ethylene titanate, di (dioctyl pyrophosphate) ethylene titanate and the like can be mentioned.

Examples of the aluminum compound include ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), aluminum isopropylate, monosec-butoxyaluminum diisopropylate, and aluminum sec. -Petite and the like.

Examples of the zirconium compound include tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, tetra-n-butyl zirconate, tetra-tert-butyl zirconate, tetra-sec-butyl zirconate, and tetraisopentyl. Zirconate,
Tetra-n-hexyl zirconate, tetra-iso-hexyl zirconate, tetra-n-heptyl zirconate,

Tetraisoheptyl zirconate, tetra
n-octyl zirconate, triglycolato zirconate, trilactate zirconate, zirconium tetraacetylacetonate, zirconyl stearate, zirconyl octylate, and the like.

As the titanium compound, di-n-butoxybis (triethanolamine) titanate, dihydroxybis (lactiquaside) titanate, di-i-propoxybis (acetoacetic acid) are particularly preferable. Ethyl) titanate, di-i-propoxybis (acetylacetone) titanate, etc., and particularly preferably the aluminum compound is monosec butoxyaluminum diisopropylate, aluminum isopropylate, etc. Particularly preferred examples of the zirconium compound include triglycolate zirconate, trilactate zirconate, and zirconium tetraacetylacetonate.

In the present invention, a titanium compound, an aluminum compound, a zirconium compound or the like can be used in combination as the organometallic compound.

As the silane compound, for example, γ
-(2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ -
Aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane,

Hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyl Dimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane,

Vinyltriethoxysilane, β- (3.4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β ( (Aminoethyl) γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, N-
Phenyl-γ-aminopropyltrimethoxysilane,

The silane compound is particularly preferably γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, -Mercaptopropyltrimethoxysilane, methyltrimethoxysilane, hexamethyldisilazane, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane,

Vinyltrichlorosilane, vinyltriethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxy Silane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxy Silane, and the like.

Further, in the present invention, when the organometallic compound or the silane compound is used in combination with the organometallic compound and the silane compound, the effect of the present invention is remarkably obtained, which is a particularly preferred embodiment.

To explain the present invention in detail, a conventional aqueous pigment dispersion using a polymer dispersant has a considerably high viscosity, and the viscosity of such a conventional aqueous pigment dispersion is
When the viscosity was lowered to obtain a viscosity suitable for ink jet recording (1 to 30 _CPS ), pigment particles were confused and settled, making it impossible to use the ink for ink jet recording.

After extensive studies to obtain an aqueous pigment dispersion having high dispersion stability and a fine dispersion suitable for an ink jet recording liquid, an oligomer emulsifier having an alkyl sulfide terminal group and a molecular weight of 200 to 5000 and a pigment were obtained. It has been found that when a water-soluble medium and an organometallic compound or a silane compound are mixed and ground, the pigment is very finely dispersed and the storage stability thereof is extremely high.

When an organometallic compound or a silane compound is added to a pigment and an oligomer-emulsifier or a water-soluble organic solvent and mixed and ground, a polar group present on the surface of the pigment, the oligomer-emulsifier and the water-soluble organic solvent becomes an organic metal compound or It is considered that the interaction is performed by using the silane compound, so that aggregation of the pigment does not occur, and the pigment is stably dispersed in the aqueous medium. Also, surprisingly, they have found that the pigment is excellent in re-dispersibility and can be printed normally even at a high temperature without clogging.

The oligomer emulsifier used as the emulsifier in the present invention is mainly an oligomer polymer of a monomer having an addition-polymerizable vinyl group and a mercaptan having a long-chain alkyl group. ) And / or (2)

[0045]

Embedded image

[0046]

Embedded image

R ₁ : an alkyl group having 5 to 20 carbon atoms (that is, all groups represented by the general formula CnH ₂ n + ₁ )

R ₂ , R ₃ , R ₅ : hydrogen or an alkyl group having 1 to 5 carbon atoms (general formula C _n H _{2n + 1} ), or a carboxyl group, a carboxylate ester group or an ammonium base, amine base or alkali of a carboxylic acid Metal base or alkaline earth metal base

R ₄ : hydrogen, halogen or an alkyl group having 1 to 4 carbon atoms (general formula C _n H _{2n + 1} ) X: cyano group, —COOCH ₃ group, —OCOCH ₃ or —OCOC ₂ H ₅ Y: hydrogen, ammonium Group, amine base, alkali metal or alkaline earth metal

And these can be used alone or in combination of two or more.

Examples of the hydrophobic moiety include alkyl mercaptans having an alkyl group having 5 to 20 carbon atoms. Specific examples include n-butyl mercaptan, n-hexyl mercaptan, octyl mercaptan, decarmercaptan, dodecyl mercaptan, and tetradecane. It is introduced into the polymer terminal using an alkyl mercaptan such as a mercaptan. Particularly preferred are octyl mercaptan and dodecyl mercaptan.

On the other hand, as the monomer unit for introducing a hydrophilic moiety, a monomer having a carboxyl group, specifically, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid And α-β-unsaturated monomers such as monoester, fumaric acid and fumaric acid monoester, and monomers such as acrylonitrile, methylacrylonitrile, ethylacrylonitrile, vinyl acetate, styrene and styrene derivatives.

It can be used in the range of b / (a + b) = 0.45 to 0.95, particularly preferably in the range of 0.5 to 0.8. When the above ratio is less than 0.45, hydrophilicity is lacking, and dispersibility of the pigment is deteriorated.

In the present invention, it is necessary to form a salt of the oligomer for the purpose of solubilizing the oligomer in an aqueous liquid. Examples of such salts include ammonium salts, amine salts such as aliphatic amines or alcoholamines, alkali metal salts such as Na or K, and alkaline earth metal salts.

The molecular weight of the oligomer emulsifier used in the present invention is preferably from 200 to 5,000, more preferably from 500 to 4,000.
Having a molecular weight of If the molecular weight exceeds 5,000 and is too high, the viscosity of the dispersion tends to increase, and stable ejection as an inkjet recording ink may not be obtained in some cases. If the molecular weight is too low, less than 200, the dispersion stability of the pigment tends to be poor, resulting in poor long-term storage stability.

The oligomer-emulsifier having an alkyl sulfide terminal group used in the present invention can be prepared by any known polymerization method such as bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization under high pressure, etc. The polymerization is carried out by a usual radical polymerization method, but solution polymerization and bulk polymerization are preferred because those having a relatively small molecular weight are easily obtained.

For example, in a low boiling alcohol solvent having a temperature of 100 ° C. or less (eg, methanol, ethanol, propanol)
Solution polymerization using a persulfate or a peroxide and, if necessary, a reducing agent in the presence of an alkyl mercaptan, and adding an alkali metal hydroxide such as potassium hydroxide and water. _{It is} obtained by adjusting the pH to 5 to 9 and removing the alcohol solvent and the residual monomer under reduced pressure.

In the polymerization, the monomer mixture, the polymerization initiator, and the alkyl mercaptan may be charged all at once from the beginning of the polymerization, or only a part may be charged at the beginning and the remaining mixture may be charged with the progress of the polymerization reaction. It may be dropped.

The preferred amount of the organometallic compound or silane compound varies depending on the type of the pigment and the emulsifier, but is preferably 0.05 to 10% by weight based on the total weight of the pigment and the emulsifier, and particularly preferably 0.1 to 10% by weight. Can be used in the range of ~ 5% by weight. In the present invention, it is preferable to use the pigment as a dispersion liquid having a particle diameter of 1 to 20 times the primary particle diameter.

The pigment is used as a coloring agent, and various known pigments can be used. Specific examples thereof include azo pigments, condensed polyazo pigments, phthalocyanine pigments, quinacdrine pigments, and anthraquinone pigments. Organic pigments such as dioxazine pigments, indigo pigments, isoindolenone pigments, thioindigo pigments, perinone pigments, perylene pigments; inorganic pigments such as titanium oxide, iron oxide, and carbon black; and fluorescent pigments Is mentioned.

As long as the dye is insoluble in an aqueous solvent, various known dyes can be used. Specific examples of the water-insoluble dye include basic dye lakes and acid dye lakes. Lake dyes and nigrosine dyes are exemplified. Furthermore,
Of course, pigments that have been subjected to a graft treatment or surface treatment can also be used as the above-mentioned pigments.

Particularly, carbon black can be typically used for a black recording liquid, but the viscosity of the dispersion liquid tends to be high.
Also, it has been difficult to maintain the dispersed particle size over a long period of time. However, when an oligomer emulsifier having an alkyl sulfide terminal group is used, the amount of DBP adsorbed is 70 to 200 [DBP ml / mg], and carbon black having a pH of 2 to 6 is dispersed. It was found that the viscosity of the liquid was low, and there was no liquid separation or sedimentation over a long period of time, and the initial dispersion particle size was maintained.

The suitable concentration of the pigment in the ink is determined by its influence on the coloring power and ink viscosity, but can be used in the range of 2 to 30% by weight based on the total weight of the ink.
The preferred concentration of the oligomer-emulsifier varies depending on the type of the pigment, but can be used in the range of 2 to 40% by weight, more preferably 3 to 30% by weight, based on the weight of the pigment.
The storage stability is poor at the weight end, and if it exceeds 40% by weight,
Bubbling is likely to occur, and stable ejection cannot be obtained.

[0064] Also, in addition to the above essential components in the recording liquid used with the present invention, various known additives such as a water-soluble organic solvent, _P H modifiers, defoamers, preservatives, surface tension adjusting agent ,
Surfactants, salts, synthetic and natural resins, various dyes and the like can be used in combination.

[0065] As the modifier of _P H, for example, Jietano -
Various organic amines such as ruamine and triethanolamine,
Examples include inorganic alkali agents such as hydroxides of alkali metals such as sodium hydroxide, lithium hydroxide and potassium hydroxide, organic acids and mineral acids.

As synthetic and natural resins, water-soluble resins and emulsion resins can be used.
Proteins such as gelatin, albumin and casein, natural gums such as gum arabic and tragacanth, glucosides such as saponin, methylcellulose, carboxycellulose
, Cellulose derivatives such as hydroxymethylcellulose, ligninsulfonate, natural polymers such as shellac,
Polyacrylate, styrene-acrylic acid copolymer salt,

Salt of vinyl naphthalene-acrylic acid copolymer, salt of styrene-maleic acid copolymer, salt of vinyl naphthalene-maleic acid copolymer, sodium salt of β-naphthalene sulfonic acid formalin condensate, phosphate And the like, nonionic polymers such as anionic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyethylene glycol.

Examples of the emulsion resin include synthetic resin emulsions such as vinyl acetate emulsion, acrylate / methacrylate emulsion, styrene emulsion, urethane emulsion and ethylene vinyl acetate emulsion.

Examples of the surfactant include anionic surfactants such as fatty acid salts, higher alcohol sulfate salts, liquid fatty oil sulfate salts, alkyl allyl sulfonates, and polyoxyethylene alkyl ethers. And non-ionic surfactants such as polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters.

Examples of the water-soluble organic solvent used by mixing with water include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol and isopropyl alcohol.
, N-butyl alcohol, sec-butyl alcohol, tert
-1 carbon atoms such as butyl alcohol and isobutyl alcohol
-4 alkyl alcohols; amides such as dimethylformamide and dimethylacetamide;

Ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol Alkylene groups such as propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; Alkylene glycols containing 5 carbon atoms;

Glycerin; polyhydric alcohols such as ethylene glycol methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether
Lower alkyl ethers such as N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidin.

[0073] Among these many water-soluble organic solvents,
Polyalkyl alcohols such as diethylene glycol; lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; and ethanol.
Preferred are aliphatic monohydric alcohols such as alcohols, and they may be used in combination.

The content of these water-soluble organic solvents is from 10 to 80
%, More preferably in the range of 20 to 60% by weight. When the content is less than 10% by weight, clogging at the tip of the discharge nozzle is liable to occur, and the discharge is always stable even when the driving condition changes. Cannot be obtained.

If the content exceeds 80% by weight, the printing quality tends to be impaired. The water content ranges from 10 to 80% by weight, preferably from 20 to 70% by weight.

Further, for preserving the ink for a long period of time and for suppressing the generation of bacteria and mold, known preservatives and fungicides such as dioxin and sodium tehydroacetate can be used.

Various methods can be used for adjusting the recording liquid. For example, the above components are blended, and the mixture is ball milled.
A method of mixing and grinding using a roll mill, a speed line mill, a homogenizer, a homomixer, a sand grounder, or the like can be employed, and further, coarse particles of the pigment are removed by a method such as filtration or centrifugation. Thereby, it can be easily obtained.

The pigment dispersion step is carried out in a state where the pigment concentration is as high as possible. After the dispersion treatment, if necessary, further adjustment is made by adding a resin and a medium, and the viscosity of the recording liquid is finally adjusted. The particle size of the recording agent is adjusted to about 1 to 20 cps, preferably about 2 to 10 cps, and 1 to 20 times, preferably 1 to 10 times the primary particle diameter of the pigment.

If pigment particles, especially large coarse particles having a particle diameter of 3 μm or more, are present in the ink in a large amount, when energy is applied to the ink on the ejection head, some change occurs in the ink dispersion system, and the orifice and the Foreign matter is easily deposited on the wall surface and settles easily. On the other hand, fine pigment particles, especially ink of fine particles of 0.5 μm or less,
, The dispersion system is stable, and even if the particles adhere to the wall surface, precipitation of foreign matter is unlikely to occur, and stable ejection can be obtained over a long period of time.

In the recording solution thus prepared, the pigment particles are not collected or settled even when stored for a long time in a low viscosity region.

Then, this recording liquid is obtained by: (1) a wide range of recording liquid ejection conditions (the driving voltage of the piezoelectric element,
It has liquid physical properties (viscosity, particle diameter, surface tension, specific conductivity, etc.) matching the drive frequency, the shape and material of the discharge orifice, the discharge orifice diameter, and the like.

(2) It is stable for long-term storage and does not cause clogging of the ink jet device. (3) The formed recording image has a clear color tone and a high density. (4) It has excellent fixability to plain paper, and even when printed on plain paper, the periphery of dots is smooth and does not blur.

(5) The formed recorded image is excellent in water resistance and weather resistance.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited by these Examples.
The quantities used in the following examples are based on weight unless otherwise specified.

Synthesis Example of Oligomer-Emulsifier Example 1 630 g of acrylic acid, 455 g of acrylonitrile, 160 g of n-octylmercaptan and 177 g of methanol were added to a reactor having a stirrer, a reflux condenser, a dropping device, and an N ₂ introduction pipe. ₍₂ ) After performing the substitution, heat to 35 ° C., add 67 g of a 0.6% methanol solution of ammonium persulfate to start the polymerization reaction, and 600 g of a 0.6% solution of ammonium persulfate in methanol.
Was added dropwise over 6 hours, and the reaction was continued until the conversion exceeded 99.5%.

[0086] The obtained methanol - Le solution after dried under reduced pressure at 100 ° C. 10 mmHg, and neutralized dissolved in aqueous potassium hydroxide, nonvolatile content 40%, _P pH 7.0, acrylic acid having a molecular weight of about 1200 4
A potassium salt of a copolymer of 7.5 mol%, acrylonitrile 46.5 mol%, and n-octyl mercaptan 6.0 mol% was obtained.

Example 2 In the same reactor as in Example 1, 663 g of itaconic acid, 260 g of acrylonitrile, 78 g of n-dodecylmercaptan and 540 g of isopropanol were added, and after N ₂ substitution, the mixture was heated to 40 ° C.
Thereafter, 40 g of a 1% solution of lauroyl peroxide in isopropyl alcohol was added to initiate the polymerization reaction, and 360 g of a 1% solution of lauroyl peroxide in isopropyl alcohol was added dropwise over 6 hours to carry out the reaction.

By performing the same processing as in Example 1, the nonvolatile component
40%, _P H6.5, 49.1 mole% of itaconic acid having a molecular weight of 3,800, acrylonitrile 47.2 mol% and a sodium salt of n- dodecyl mercaptan 3.7 mol% of the copolymer.

Example 3 A copolymer was obtained from the following raw materials in the same manner as in Example 1. Acrylonitrile 144 g Acrylic acid 780 g n-octyl mercaptan 164 g Isopropanol 690 g Lauroyl peroxide 10 g

[0090] The obtained copolymer examples nonvolatile content of 40% was treated in the same manner as -1 _P pH 7.0 73.8 mol% molecular weight of about 800 acrylic acid, acrylonitrile 18.5 mol%, n-octyl mercaptan 7.7 mol% A potassium salt of the copolymer was obtained.

Example-4 413 g of vinyl acetate 706 g of maleic anhydride 121 g of n-dodecyl mercaptan 121 g 820 g of isopropanol 4.5 g of ammonium persulfate

[0092] nonvolatile content 40%, _P H7.5, 57.0 mol% molecular weight of about 2,000 maleic acid, vinyl acetate 38.2 mol%, was obtained potassium salt of n- dodecyl mercaptan 4.8 mol% of the copolymer.

Example-5 Styrene 374 g Maleic anhydride 823 g n-octyl mercaptan 88 g Isopropanol 850 g Lauroyl peroxide 10 g

[0094] nonvolatile content 40%, _P pH 7.0, 66.7 mol% molecular weight of about 1,000 maleic acid, styrene 28.5 mol%, was obtained potassium salt of n- dodecyl mercaptan 4.8 mol% of the copolymer.

Example-1 0.7 part by weight of the aqueous solution of the potassium salt of the copolymer obtained in Synthesis Example-1 7 parts by weight of carbon black 10 parts by weight of triethylene glycol 3 parts by weight of glycerin Dihydroxybis (lactic acid) 0.8 parts by weight Titanate Sodium tetrahydroacetate 0.1 parts by weight Water 76.4 parts by weight

The above-mentioned components were used in a gorin homogenizer.
(Mount Gorling Co., Ltd.), and filtered through a 1200 mesh wire net to obtain a black recording liquid. The viscosity of the obtained ink is about 2 cps at 20 ° C. and the average particle diameter is 0.12 μm
And it was about 4.1 times the primary particle diameter. Table 1 shows the results of various tests.

Example-2 1.5 parts by weight of the aqueous solution of the sodium salt of the copolymer obtained in Synthesis Example-2 7 parts by weight of carbon black used in Example-1 10 parts by weight of triethylene glycol 5 parts by weight of glycerin di -i-Propoxy bis (acetylacetone) 0.6 parts by weight Sodium titanate 0.1 part by weight Water 75.8 parts by weight

The above components were dispersed in the same manner as in Example 1,
A black recording liquid was obtained. The viscosity of the obtained ink was about 3 cps at 20 ° C., the average particle diameter was 0.16 μm, and was about 5.5 times the primary particle diameter. Table 1 shows the results of various tests.

Example 3 6 parts by weight of the aqueous solution of the potassium salt of the copolymer obtained in Synthesis Example 3 7 parts by weight of the carbon black used in Example 1 7 parts by weight of isopropyl alcohol 14 parts by weight of diethylene glycol Mono sec-butoxyaluminum 0.8 parts by weight diisopropylate

Dispersing the above components into a disperser (specialized machine)
Then, 65.2 parts by weight of water was added thereto, and Example-1
And a black recording liquid was obtained. The viscosity of the obtained ink was about 2 cps, the average particle diameter was 0.18 μm, and was about 6 times the primary particle diameter. Table 1 shows the results of various tests.

Example 4 1 part by weight of the aqueous solution of the potassium salt of the copolymer obtained in Synthesis Example 4 7 parts by weight of carbon black used in Example 1 13 parts by weight of triethylene glycol 4 parts by weight of glycerin Tris (Acetylacetonate) zirconium 0.5 parts by weight Ammonium lactate Sodium tetrahydroacetate 0.1 parts by weight Water 74.4 parts by weight

The above components were dispersed in the same manner as in Example 1,
A black recording liquid was obtained. The viscosity of the obtained ink is about 3 cps
The average particle size was 0.12 μm, which was about 4.1 times the primary particle size. Table 1 shows the results of various tests.

Example-5 0.5 part by weight of the aqueous solution of the potassium salt of the copolymer obtained in Polymerization Example-5 7 parts by weight of carbon black used in Example-1 0.5 part by weight of γ-glycidoxypropyltrimethoxysilane ( Toray Dow Corning Silicone Co.) Triethylene glycol 10 parts by weight Glycerin 4 parts by weight Sodium tetrahydroacetate 0.1 parts by weight Water 77.9 parts by weight

The above components were dispersed in the same manner as in Example 1,
A black recording liquid was obtained. The viscosity of the obtained ink is about 3 cps
The average particle diameter was 0.15 μm, which was about 5.2 times the primary particle diameter. Table 1 shows the results of various tests.

Comparative Example 1 Styrene-maleic acid copolymer 15 parts by weight Trade name SMA Resin 1440H (Alcochemical Co., Ltd.) Carbon black used in Example 1 7 parts by weight Ethylene glycol 10 parts by weight Glycerin 3 Parts by weight sodium tehydroacetate 0.1 parts by weight water 64.9 parts by weight

The above components were dispersed in the same manner as in Example 1,
A black recording liquid was obtained. The viscosity of the obtained ink is about 10cp
In s, the average particle size is 0.25 μm, about 8.6 of the primary particle size.
It was twice.

Comparative Example-2 20 parts by weight of sodium formalin condensate of naphthalene sulfonate Demol N (Kao Atlas) 7 parts by weight of carbon black used in Example-1 10 parts by weight of ethylene glycol 4 parts by weight of glycerin Sodium tehydroacetate 0.1 parts by weight Water 58.9 parts by weight

The above components were dispersed in the same manner as in Example 1,
A black recording liquid was obtained. The viscosity of the obtained ink is about 20cp
In s, the average particle size was 0.29 μm, which was about 10 times the primary particle size.

Comparative Example-3 0.5 part by weight of the aqueous solution of the potassium salt of the copolymer obtained in Polymerization Example-1 7 parts by weight of carbon black used in Example-1 0.04 part by weight of dihydroxybis (lactic acid) titanate G water 92.5 parts by weight

The above components were dispersed in the same manner as in Example 1,
A black recording liquid was obtained. The viscosity of the obtained ink is about 2 cps
The average particle size was 0.17 μm, which was 5.9 times the primary particle size.

Using the inks of Examples 1 to 5 and Comparative Examples 1 to 3, the storage stability of the recording liquid and the on-demand recording head (orifice diameter of the discharge nozzle of 25 μm) for discharging the ink by the piezo vibrator were used. With the use of a recording apparatus having the same, the mechanical suitability (dischargeability) as an ink for inkjet recording and the printing quality were examined. The results are summarized in Table 1.

The test methods, evaluation methods, and terms used in the present invention are described below. 1. Measurement of average molecular weight The molecular weight was measured under the following conditions by mounting a column (3 GMHs, manufactured by Tosoh Corporation) on a gel permeation chromatography (GPC). The sample was dissolved in THF (tetrahydrofuran) at a concentration of 0.2 wt%, and 1 ml at 20 ° C.
/ Min flow rate.

When measuring the molecular weight of a sample, a measurement condition in which the logarithm of the molecular weight of the sample and the logarithm of the molecular weight of the calibration curve prepared from several kinds of monodisperse polystyrene standard samples and the count number are linear is used. Selected. Further, the molecular weight was represented by a number average molecular weight (Mn).

2. Measurement of Viscosity of Recording Solution The viscosity was measured using a Rheomat 30 viscometer manufactured by Contraves.

3. Measurement of Primary Particle Diameter of Pigment and Particle Diameter of Dispersion The primary particle diameter of the pigment is an average particle diameter calculated from the primary diameter and the number of pigment particles by an electron micrograph. The particle size of the dispersion is `` DLS-700 '' manufactured by Otsuka Electronics Co., Ltd.
c Light Scattering Spectrophotometer). 1 ≦ particle size of pigment dispersion ÷ primary particle size of pigment agent ≦ 10

4. Preservation of Ink The ink was sealed in a glass container, stored at -5 ° C and 70 ° C for 6 months, and examined for changes. (Evaluation) ；: No liquid separation of the recording liquid and no sedimentation of the recording agent were observed. ；: Some separation of the recording liquid was observed, but no sedimentation of the recording agent was observed, and the recording liquid returned to its original state by weak shaking. C: Separation of the recording liquid and sedimentation of the recording agent were observed, and they did not return to the original state with only slight shaking.

5. Discharge stability 5,000 sheets were continuously discharged in an atmosphere at room temperature of 5 ° C. and 40 ° C., respectively, and the recording stability was examined. (Evaluation) A: Stable ejection continued. X: Weakness occurred in discharge.

6. Print Density A test piece was printed on a commercially available copy paper (P paper manufactured by Xerox Corporation) and measured with a Macbeth densitometer.

7. Printing Quality In the above-mentioned paper, the spread of dot diameter (bleeding) and the breakage of dots (roundness) when one-dot printing was performed were evaluated by an optical microscope. (Evaluation) ；: Less bleeding and higher roundness. ；: Less bleeding but low roundness. ×: Much blurring and low roundness.

8. Print fixability Stain when the above-mentioned print test piece was rubbed with the above-mentioned copy paper was visually judged. (Evaluation) A: There is no stain. X: The periphery of the printing portion is stained.

9. Restartability The recording apparatus was placed in a constant temperature and constant humidity of 20 ° C., 60% RH and 60 ° C., 20% RH, and after continuous operation for 1 hour, the operation was stopped and the recording head was completely stopped. It was left open for 15 minutes, and the print quality was checked when it was restarted.

[0122]

[Table 1]

[0123]

The ink jet recording liquid of the present invention has excellent ink properties with little sedimentation and liquid separation properties, and has excellent mechanical properties such as dischargeability, continuous stability and non-clogging properties. Good drying resistance, fixability,
It has excellent printing characteristics such as printing density and printing quality.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-102407 (JP, A) JP-A-56-147868 (JP, A) JP-A-60-76574 (JP, A) JP-A Sho 62- 177070 (JP, A) JP-A 1-161075 (JP, A) JP-A 64-6072 (JP, A) JP-A 4-25573 (JP, A) JP-A 5-65443 (JP, A) JP-A-6-41480 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-11/20

Claims (1)

(57) [Claims] An aqueous pigment-dispersed inkjet recording liquid in which the medium is an aqueous medium containing a water-soluble organic solvent, wherein a pigment, an oligomer emulsifier represented by the following general formula (1) or (2), an organometallic compound or a silane compound is used. An ink jet recording liquid characterized by containing. R ₁ : alkyl group having 5 to 20 carbon atoms (that is, all groups represented by the general formula C _n H _{2n + 1} ) R ₂ , R ₃ , R ₅ : hydrogen or alkyl having 1 to 5 carbon atoms A group (general formula C _n H _{2n + 1} ), or a carboxyl group, a carboxylic ester group or an ammonium base of a carboxylic acid,
Amine base, alkali metal base or alkaline earth metal base R ₄ : hydrogen, halogen or alkyl group having 1 to 4 carbon atoms (general formula C _n H _{2n + 1} ) X: cyano group, —COOCH ₃ group, —OCOCH ₃ or — OCOC ₂ H ₅ Y: represented by hydrogen, ammonium group, amine base, alkali metal or alkaline earth metal, and b / (a + b) is 0.45 to
It is in the range of 0.95.