JP3097208B2 - Ink for inkjet printer - 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 for flying an ink to form a character or an image on a recording medium such as a recording paper for use in an ink jet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, ink jet recording systems can be roughly classified into two types, a continuous type and an on-demand type. As an ink used in such an ink jet system, an ink in which a dye is dissolved in water is mainly used (hereinafter, referred to as an aqueous ink). As the aqueous ink, those obtained by dissolving various water-soluble dyes in water or a solvent composed of water and a water-soluble water-soluble organic solvent and adding various additives as necessary are currently used. The advantage of these ink jet recordings is that the process is simple because of direct recording. No impact method, no noise, easy colorization, high-speed printing, low running cost because plain paper can be used, high-resolution printing to discharge minute ink droplets It has excellent features such as being possible, and its future is attracting attention.

[0003]

However, in the above-mentioned prior art, although slightly different depending on the method, the common technical problems are as follows: 1. Ink bleeds on the paper to be transferred, and a high-quality recorded image cannot be obtained. .

[0004] 2. The drying speed of the ink on the transfer receiving paper is low, and snoring occurs.

[0005] (3) clogging of the nozzles and the ink supply path, and unstable ink discharge.

Attempts have been made to solve the above-mentioned problems. For example, Japanese Patent Publication No. 55-29546 discloses a method of adding a specific surfactant to lower the surface tension of a paper to which ink is to be transferred. Japanese Patent Publication No. 56-57862 discloses a method of increasing the pH by adding a strongly basic substance to a sizing agent or a pulp agent which is a water-resistant treatment agent for plain paper. A method of controlling the spread and absorption of the dots by dissolving them in a suitable manner has been reported. Japanese Patent Publication No. 58-13675 discloses a method in which polyvinylpyrrolidone having a molecular weight of 40,000 or more is added to the ink to spread and cover the dots. Although methods for controlling the absorbency of transfer paper have been proposed, these attempts solve some of the above problems, but do not provide a solution to all of the problems. In addition, since these inks use a water-soluble dye, when ink-jet recording is performed, the water resistance and light resistance on the receiving paper are inferior. Further, the storage stability of the recording liquid itself containing the water-soluble dye is not so high due to spontaneous decomposition of the dye.

Therefore, recently, an attempt has been made to apply a pigment-based ink-jet printer ink to the ink-jet recording system in place of such a dye-based ink-jet printer ink. This pigment-based ink for inkjet printers has an advantage that the obtained recorded image has extremely good light fastness and water fastness as compared with the above dye-based inks. However, since the pigment is insoluble in the ink dispersion medium, it requires a high level of technology to finely disperse the pigment in the ink, and it is very difficult to enhance the dispersion stability.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and firstly, to provide an ink for an ink jet printer having excellent storage stability of a recording liquid itself. Secondly, ink bleeds on the receiving medium
It is difficult to obtain a high-quality recorded image. Third, the drying speed of the ink on the receiving paper is high, and no snoring occurs. Fourth, it is an object of the present invention to provide an ink jet printer ink that does not clog the nozzles and the ink supply path and stabilizes the ink ejection. Another object of the present invention is to provide an ink jet printer ink excellent in water resistance and light resistance on a receiving paper.

[0009]

The ink for an ink jet printer according to the present invention is an ink for an ink jet printer obtained by dispersing at least a pigment and insoluble resin particles in a dispersion medium, wherein the pigment is an organic silane coupling agent. and one selected from the group consisting of an organic titanium coupling agent and an organic phosphate-based coupling agent and a chromium-based coupling agent and silyl peroxide coupling agent
Chemically treated with a coupling agent, characterized in that the other reactive group of the coupling agent is reacted with the insoluble resin particles.

[0010] The dispersion medium is a non-polar insulating solvent.

[0011]

Embodiments of the present invention will be described below in detail.

The ink adjusting method of the present invention was performed as follows. The insoluble resin particles are dispersed in a dispersion medium (the resulting one is hereinafter referred to as a dispersion solution). A coupling agent that causes a chemical bonding reaction with the surface functional groups of the insoluble resin particles dispersed in this dispersion solution was gradually added. After the addition of the coupling agent, the dispersion was kept at 50 ° C., and the reaction proceeded for a time proportional to the ink volume. In this case, the standard of the reaction time is preferably 2 to 3 hours per 100 ml of the dispersion solution. At this time, a catalyst may be added for the purpose of promoting a chemical reaction between the insoluble resin particles and the coupling agent. FT indicates that the chemical reaction between the completely insoluble resin particles and the coupling agent has been completed.
After confirming using -IR, the dispersion solution is transferred to an attritor, the pigment is added in a specified amount, and dispersed for 12 hours (the amount of the dispersion solution is 300 ml as a guide at this time). At the same time, a chemical bonding reaction between the coupling agent and the pigment was performed to obtain a homogeneous dispersion. Thereafter, by-products generated by a chemical bond between the silane coupling agent and the pigment or the resin are removed.

If necessary, a dispersing agent is added and dissolved, and then the mixture is filtered through a filter or the like in order to remove giant particles, dust and the like, whereby the ink for an ink jet printer of the present invention can be obtained. Needless to say, the coupling reaction step is not limited to this.

The viscosity of the ink for an ink-jet printer adjusted by the above-described ink manufacturing method is such that when the temperature during operation of the printing apparatus is set to 0 to 50 ° C., From the viewpoint of droplet formation stability and flight stability, 3
It is necessary that the pressure be 0 mPa · s or less, and 1 to 15 mPa · s is more preferable for realizing high-speed response.

The components of the ink are specifically illustrated below.

As the pigment, various organic or inorganic pigments including conventionally known pigments can be used. Examples include carbon black, insoluble azo pigments, phthalocyanine-based pigments, isoindolinone-based pigments, quinacridone-based pigments, penoline / perylene-based pigments, anthraquinone-based pigments, dioxazine-based pigments, indigo-based pigments, and thioindigo-based pigments. Pigments, metal oxides (iron oxide, titanium oxide, cadmium oxide, chromium oxide, etc.) and the like can be mentioned. In addition, a processed pigment in which the surface of pigment particles is coated with a resin can also be used. These may be used in combination of two or more in some cases.

The insoluble resin particles that can be used in the ink jet printer ink of the present invention include polyvinyl acetate resin particles, vinyl acetate copolymer resin particles (for example, vinyl acetate acrylate, vinyl acetate dibutyl maleate, Vinyl acetate veoba, vinyl acetate ethylene), acrylate ester copolymer resin particles (eg, acrylate methyl methacrylate,
Acrylate styrene), other thermoplastic resin particles (eg, vinylidene chloride copolymer, vinyl chloride copolymer, polyethylene), thermosetting resin particles (eg, epoxy resin), synthetic resin particles (eg, butadiene styrene) , Butadiene acrylonitrile) and the like. These insoluble resin particles may be used in combination of two or more in some cases.

Examples of the coupling agent that can be used in the ink for an ink jet printer of the present invention are shown below.

Examples of the organic titanium-based coupling agent include, for example, tetraisopropyl titanate, tetrabutyl titanate, tetrastearyl titanate, isopropoxy titanium stearate and the like.

As the chromium-based coupling agent, Du is used.
Pont's Volan, Valchem's Valc
home 5015 and the like.

Examples of the silyl peroxide-based coupling agent include those represented by the following structural formula.

[0022]

Embedded image

Examples of the organic phosphoric acid-based coupling agent include those represented by the following structural formula.

[0024]

Embedded image

As the organic silane coupling agent, vinyl trichlorosilane, vinyl tris (β-methoxyethoxy) silane, vinyl triethoxy silane, vinyl trimethoxy silane, γ-methacryloxypropyl trimethoxy silane, β- (3,4 epoxy Cyclohexyl) ethyltrimethoxysilane. γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl)
γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like.

The coupling agent of the present invention is not limited to the above examples, and any coupling agent can be used as long as it shows a coupling reaction with the pigment and the insoluble resin particles in the ink. .

As the dispersion medium usable in the present invention, hydrophilic solvents include water or polyhydric alcohols having a high boiling point, low volatility and high surface tension, such as glycerin, ethylene glycol and diethylene glycol, and triethylene glycol. Polyhydric alcohols such as propylene glycol and polyethylene glycol, or monoetherified, dietherified and esterified compounds thereof, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Diethylene glycol monobutyl ether, etc., other N-methyl 2-pyrrolidone, 1.3-dimethylimidazolidinone, ethylformamide There are water-soluble organic solvents such as nitrogen-containing organic solvent. Examples of the hydrophobic solvent include silicon oil having a siloxane bond, isobutylene, vinyl chloride, and the like, and non-polar solvents such as mineral spirit, pentane, hexane, octane, petroleum naphtha, cyclohexane, heptane, and the like.

The above-mentioned dispersion media can be used in the present invention, but those having a low saturated vapor pressure and a high boiling point are particularly preferable from the viewpoint of preventing clogging of the ink discharge head. Specifically, a non-polar insulating solvent or the like can be considered. Examples of non-polar insulating solvents include, for example, aliphatic hydrocarbon solvents, Exxon Isopar, Philippe Petrochemicals Soltor, Idemitsu Petrochemicals IP Solvent, and Shell Petrochemicals S.P. B. R. , Shersol, Vegasol of Mobile Oil Company, and the like. The properties required for the dispersion medium of the present invention are low toxicity, low flammability, and low odor. These may be used in combination of two or more in some cases.

In the present invention, a dispersant can be added if necessary, and known nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, fluorine-based surfactants, It is also possible to use a silicon-based or polymer dispersant in combination.

Examples of anionic surfactants include higher fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, sulfosuccinates, and naphthenates. And so on. Examples of the cationic surfactant include an aliphatic amine salt, a quaternary ammonium salt, a sulfonium salt,
Examples thereof include phosphonium salts, and specific examples thereof include octadecylamine acetate, alkyltrimethylammonium chloride, polyoxyethylene octadecylamine, polyoxyethylene alkylamine, and polymer amine.

Examples of the amphoteric surfactant include betaine such as dimethylalkyl betaine. As the nonionic surfactant, a fatty acid ester type of a polyoxyethylene compound, a polyethylene oxide condensed type, or the like can be used.

The components of the ink will be specifically described below.

Tables 1 and 2 show the ink compositions of Examples 1 to 10 of the present invention and the ink compositions of Comparative Examples 1 to 10 .
Comparative Example 2 is shown.

[0034]

[Table 1]

[0035]

[Table 2]

The ink composition of Comparative Example 2 shown in Table 2 is almost the same as a commercially available aqueous ink. After preparing the ink, the following evaluation items were provided, and the ink for an inkjet printer of the present invention and the ink of the comparative example were evaluated.

Ink storage stability: The ink sealed at a high temperature of 70 ° C. was allowed to stand for 4 months, and then observed. ... preferred (◎) ・ Settlement is observed but no aggregation (hard cake) has occurred. ··· (○) Suitable-Sedimentation aggregation has occurred. ··· Classification and evaluation based on inappropriate (x). Table 3 shows the evaluation results of the inks of the examples, and Table 4 shows the evaluation results of the inks of the comparative examples.

[0038]

[Table 3]

[0039]

[Table 4]

Next, the ink printing evaluation for the purpose of evaluating the printing quality of the ink, the drying speed on the recording paper, and the clogging test at the discharge section was performed using an ink jet printer head as shown in FIG. FIG. 1 is a sectional view showing the structure of an ink jet head used in this embodiment. Specifically, it has a structure in which a pressure generating member 2 composed of laminated piezoelectric elements is bonded to the wall surface of the cavity 3. At the time of driving, the ink in the cavity is pressurized by applying pressure to the ink in the cavity by bending the pressure generating member 2 by the applied voltage.
It is discharged from. In FIG. 1, reference numeral 4 denotes ink, and reference numeral 5 denotes ink droplets ejected from the nozzle 1. The discharge nozzle diameter of this inkjet printer head was 50 μm, the piezoelectric element driving voltage was 50 V, the driving frequency was 2 kHz, and the resolution was 300 dots / inch.

According to the structure of the ink jet printer head as described above, the ink transfer area is wide due to the high ejection speed, the number of dots can be reduced, the resolution can be increased, and the margin for the ink physical properties such as viscosity and surface tension can be obtained. Excellent characteristics as an ink jet printer, such as wide, hard to clog, etc. are obtained.

The following evaluation was performed using the above-described ink jet printer head.

Print evaluation: Confirmation of print quality and ink drying property on recording paper.

Printing quality: After printing on various types of receiving paper,
The presence or absence of bleeding of the ink is evaluated by visual observation or microscopic observation (× 60). No bleeding can be confirmed by visual or microscopic observation.・ ・ Suitable (◎) ・ Bleeding cannot be confirmed visually, but can be confirmed by microscopic observation. -Appropriate (O)-Bleeding can be confirmed both visually and with a microscope.・ · Classified and evaluated according to inappropriate (×). Table 3 shows the evaluation results of the inks of the examples, and Table 4 shows the evaluation results of the inks of the comparative examples.

Ink drying property: After full solid printing, the time until ink transfer is eliminated by matching another recording paper to the printing surface is examined. Ink transfer is stopped within 5 seconds. ... preferred (◎) ・ Ink is not transferred within 60 seconds. ··· Appropriate (・) ・ It takes 60 seconds or more until set-off stops. ··· Classification and evaluation based on inappropriate (x). Table 3 shows the evaluation results of the inks of the examples, and Table 4 shows the evaluation results of the inks of the comparative examples.

Ink clogging test: A head having the structure shown in FIG. 1 was filled with ink, and left for 1 week in a 40 ° C. environment without a cap on a nozzle to evaluate the ink discharge status. Discharge: Suitable (A)-Rubbing with a rubber plate Discharge: Appropriate (O)-Not discharged: Not suitable (X) Table 3 shows the evaluation results of the inks of the examples, and Table 4 shows the evaluation results of the inks of the comparative examples.

The inks for ink jet printers of the present invention have high ink storage stability in all the evaluations carried out this time, have high print quality without bleeding, and do not show off the ink on the paper to the overlaid paper. The time was short, and good results were also obtained in a clogging test at the nozzle portion of the ink, which was preferable as an ink for an ink jet printer. On the other hand, in the inks of Comparative Examples 1 and 2,
Any of the ink storage stability, print quality, ink drying test, and nozzle clogging test was unsuitable as an ink for an inkjet printer.

Further, the ink for an ink jet printer of the present invention is a new CK paper manufactured by Xerox Co., Ltd.
When the print quality was evaluated for paper and Yamayuri paper manufactured by Honshu Paper Co., Ltd., it was possible to obtain good print quality with little bleeding or the like even for the above three types of recycled paper.

Although the embodiments of the present invention have been described in detail above, the ink for an ink jet printer of the present invention is not limited to these structures, materials, and manufacturing methods.

[0050]

As described above, according to the present invention,
High ink storage stability, no bleeding on plain paper,
It is possible to provide a good quality ink for an ink jet printer which has excellent print drying properties and does not cause nozzle clogging.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a recording method of an ink for an ink jet printer of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Pressure generating member (multilayer piezoelectric element) 3 Cavity member 4 Ink 5 Ink droplet

Claims (2)

(57) [Claims] 1. An ink for an ink jet printer comprising at least a pigment and insoluble resin particles dispersed in a dispersion medium, wherein the pigment comprises an organic silane coupling agent and an organic titanium coupling agent . Organic phosphoric acid coupling agent
And one coupling agent selected from the group consisting of a chromium coupling agent and a silyl peroxide coupling agent
Chemically treated with bridging agent, the ink for ink jet printer, characterized in that the other reactive group of the coupling agent is reacted with the insoluble resin particles. 2. The ink for an ink jet printer according to claim 1, wherein the dispersion medium is a non-polar insulating solvent.