JPH05202324A - Ink for ink jet printer - Google Patents

Abstract

(57) [Summary] [Object] To provide an ink for an ink jet printer, which is excellent in ink storage stability in a pigment dispersion system and has no bleeding on a recording paper. In an ink for an inkjet printer in which a dispersion medium is a non-polar insulating solvent and a pigment is dispersed in the dispersion medium, the average particle diameter of the dispersed pigment is 1.0 to
In the range of 2.0 μm, 70% or more of the dispersed pigment is present in the range of 1.0 to 2.0 μm, and 90 of the particle size distribution is in the range of 0.5 to 3.0 μm. % Or more of the dispersed pigment is present.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink for use in an ink jet recording apparatus for ejecting ink droplets to form characters / images on a transfer medium such as recording paper.

[0002]

2. Description of the Related Art Conventionally, as an ink used for an ink jet recording system, a water-soluble dye of various kinds is dissolved in water or a solvent consisting of water and a water-soluble organic solvent, and various additives are added if necessary. Occupies (hereinafter referred to as water-based ink). When actual printing was performed using water-based ink, there were drawbacks such as ink bleeding on the transfer medium, high-quality printing could not be obtained, and the formed recording image was inferior in water resistance and light resistance. ..

Therefore, recently, in order to improve the water resistance and light resistance of a recorded image, which is one of the problems of the above water-based ink, attempts have been made to apply a pigment-based ink to an ink jet recording system. For example, as inks for ink jet printers in which a pigment is dispersed in a non-aqueous medium, inks disclosed in JP-A-57-10660 and JP-A-57-10661 have been proposed.

[0004]

However, the pigment-based ink generally has a problem that the dispersion stability is poor because the pigment as the coloring material is insoluble in the medium. Further, the conventional pigment-based inks for inkjet recording have a problem in that although the dispersion stability is improved, the print quality is remarkably deteriorated due to ink bleeding on the recording paper.

Therefore, an object of the present invention is to provide an ink for an ink jet printer which suppresses a print bleeding on a recording paper as much as possible and realizes a high print quality, and also improves dispersion stability. ..

[0006]

In the ink for an ink jet printer of the present invention, a dispersion medium is a non-polar insulating solvent, and at least a pigment is dispersed in the dispersion medium. The average particle size of the pigment is in the range of 1.0 to 2.0 μm, and 70% or more of the particle size distribution of the pigment is present in the range of 1.0 to 2.0 μm, and 0.5 It is characterized in that 90% or more of the particle size distribution of the dispersed pigment is present in the range of ˜3.0 μm.

Further, it is characterized in that a resin and / or a dispersant is added to the ink composition. Average particle size is 1.0μ
When it is less than m (the smaller the particle diameter), the ink storage stability is improved, but the ink easily bleeds. On the contrary, the average particle size is 2.
When it is larger than 0 μm (the larger the particle diameter), the bleeding is eliminated but the ink storage stability is deteriorated. However, even if the average particle size is in the range of 1.0 to 2.0 μm, 70% or more of the particle size distribution of the dispersed pigment does not exist in the range of 1.0 to 2.0 μm and / or 0 .5-
When 90% or more of the particle size distribution of the dispersed pigment does not exist in the range of 3.0 μm, bleeding and / or ink storage stability deteriorates.

[0008]

EXAMPLES Examples of the present invention will be described in detail below.

A method of manufacturing the ink for an ink jet printer of the present invention will be described below. Add the resin to the solvent, add a dispersant if necessary and dissolve it, then add the pigment, and use a ball mill, attritor, sand mill, or other disperser to check the dispersion state with a particle size distribution analyzer, and then measure the average particle size of the pigment. The diameter is in the range of 1.0 to 2.0 μm, and 1.0 to 2.0
In the range of μm, 70% or more of the particle size distribution of the dispersed pigment is present, and in the range of 0.5 to 3.0 μm, the particle size distribution is 9%.
The pigment is dispersed until 0% or more of the dispersed pigment is present, and a uniform dispersion system is formed. Then, it can be obtained after filtering through a filter or the like to remove huge particles, dust and the like. The method for producing the ink of the present invention is not limited to this.

Ink viscosity, which is a physical property required for an ink for an ink jet printer, is stable when the temperature of the printing apparatus is set to 0 to 50 ° C. under the high speed response of the ink ejection head. From the viewpoint of stability and flight stability, it is necessary to be 30 mPa · s or less in the vicinity of the nozzle at the time of ink ejection, and 1.0 to 15 mPa · s is required to achieve even faster response.
Is more preferable.

The components of the ink will be specifically illustrated below.

The pigment used in the present invention is not particularly limited. For example, for black and white, carbon blacks such as furnace black, lamp black, acetylene black and channel black, or organic pigments such as ortho-nitroaniline black. Is mentioned. For color, toluidine red, permanent carmine FB, first yellow AAA, disazo orange P
MP, lake red C, brilliant carmine 6B, phthalocyanine blue, quinacridone red, dioxane violet, pictoria pure blue, alkali blue toner, first yellow 10G, disazo yellow AAMX, disazo yellow AAOT, disazo yellow A
AOA, yellow iron oxide, disazo yellow HR, orthonitroaniline orange, dinitroaniline orange, vulcan orange, toluidine red, chlorinated para red,
Brilliant Fast Scarlet, Naphthol Red 23, Pyrazolone Red, Barium Red 2B, Calcium Red 2B, Strontium Red 2B, Manganese Red 2B, Barium Lisome Red, Pigment Scar Red 3B Rake, Lake Bordeaux 10B, Anthocin 3B Rake, Anthocin 5B Rake, Rhodamine 6
G Lake, Eosin Lake, Bengara, Fafthor Red FGR, Rhodamine B Lake, Methyl Bio Red Lake, Dioxazine Bio Red, Basic Blue 5B Lake, Basic Blue 6G Lake, Fast Sky Blue, Alkali Blue R Toner, Peacock Blue Lake, Navy blue, ultramarine, reflex blue 2G, reflex blue R, brilliant green lake, diamond green thioflavin lake, phthalocyanine green G, green gold, phthalocyanine green Y, iron oxide powder, rust, zinc white, titanium oxide, calcium carbonate , Clay, barium sulfate, alumina white, aluminum powder, bronze powder, daylight fluorescent pigment, pearl pigment, naphthol carmine FB, naphthol red M, permanent mosquito Min FB, Fast erotic G, disazo yellow AAA, Disazo Orange PMP, Lake red C, dioxane violet, alkali blue G toner, etc., and other pigment surface processed pigments such as graft carbon treated with resins. The addition amount is 1
-30% by weight is preferable, and 3-12% by weight is more preferable. These may be used as a mixture of two or more kinds depending on the case.

The dispersion medium that can be used in the present invention is a non-polar insulating solvent, such as an aliphatic hydrocarbon solvent, specifically, Isopar manufactured by Exxon, Soltor manufactured by Philips Oil Co., and IP manufactured by Idemitsu Petrochemical Co., Ltd. For solvent and petroleum naphtha, Shell Petrochemical Co. B. R. , Shelsol, Pegasol manufactured by Mobil Oil Co., and the like. The required properties are low toxicity, low flammability, and low odor.

Examples of the resin include polar resins such as polyacrylic ester, linseed oil-modified alkyd resin, polystyrene, rosin-based resin, terpene-phenolic resin, alkylphenol-modified xylene resin, among which terpene-phenolic resin and rosin-based resin. Resins are more preferred. Further, those which are soluble in a solvent are preferable from the viewpoint of ink storability, and from the viewpoint of scratch resistance of the recorded matter after printing, the melting point or softening point of the resin is 50 ° C.
The above is preferable. Moreover, these can also use 2 or more types depending on the case.

As the dispersant, there are nonionic activators, cationic activators, anionic activators and the like. For example, sorbitan fatty acid ester (sorbitan monooleate, sorbitan monolaurate, sorbitan sesquioleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid ester (polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan) as nonionic activator Monooleate, etc.), polyethylene glycol fatty acid ester (polyoxyethylene monostearate, polyethylene glycol diisostearate, etc.), polyoxyethylene alkylphenyl ether (polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, etc.), etc. Is.
Examples of the cationic activator include octadodecylamine acetate, alkyl (hardened beef tallow) trimethylammonium chloride, polyoxyethylene octadodecylamine and the like. Examples of the anion activator include sodium dodecylbenzene sulfonate, sodium alkyl (beef tallow) methyl taurate, sodium oleyl methyl taurate, sodium dioctyl sulfosuccinate, and polymeric anion (polycarboxylic acid type). The properties required of the dispersant are those that are compatible with the non-polar insulating solvent and can stably disperse the fine particles.

Although the pigment, the dispersion medium, the resin and the dispersant have been exemplified above, the present invention is not limited thereto.

The components of the ink will be specifically described below.

In Table 1, the ink composition of the embodiment of the present invention and the average particle size of the pigment, the ratio of particles existing in the range of 1.0 to 2.0 μm, and the particles existing in the range of 0.5 to 3.0 μm are shown. Shows the ratio of.

[0019]

[Table 1]

In Table 2, the ink composition of the comparative example and the average particle size of the pigment, the proportion of particles present in the range of 1.0 to 2.0 μm and the proportion of particles present in the range of 0.5 to 3.0 μm are shown. Show.

[0021]

[Table 2]

The particle size distribution of the pigment was measured by ELS-800 electric permanent motion light scattering device manufactured by Otsuka Electronics.

After the inks having the compositions shown in Tables 1 and 2 were prepared, the following evaluation items were provided to evaluate the ink for inkjet printers of the present invention and the inks of Comparative Examples.

Ink storage stability: The ink sealed at a high temperature of 70 ° C. was left standing for 3 months and then observed. Sedimentation was observed but no agglomeration (hard cake) occurred.・ ・ ・ Suitable (○) ・ Precipitation and aggregation have occurred. ... Classified and evaluated by unsuitability (x). The results are shown in Table 2.

Print quality: Visually or microscopically observed (100 times) after printing on various transfer papers using a commercially available ink jet printer (EPSON HG-4000)
The presence / absence of ink bleeding was evaluated by, and bleeding could not be confirmed by microscopic observation.

Appropriate (○) ・ Can not be confirmed visually but can be confirmed by microscopic observation.

Inappropriate (△) ・ Bleeding can be confirmed by both visual observation and microscopic observation. ... Classified and evaluated by impossibility (x). The results are shown in Table 3.

[0028]

[Table 3]

All of the inks for ink jet printers of the present invention have high storage stability in the evaluation conducted this time, have high print quality without bleeding, and were preferable as inks for ink jet printers. On the other hand, the inks of Comparative Examples 1 and 2 were inferior to the ink for inkjet printers of the present invention in either of ink storage stability and print quality.

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 constitutions, materials and manufacturing methods.

[0031]

As described above, according to the ink for an ink jet printer of the present invention, the dispersion medium is a non-polar insulating solvent, and at least the pigment is dispersed in the dispersion medium. In the above, by defining the average particle size and the particle size distribution state of the dispersed pigment, it is possible to secure the ink storage stability, which has been a problem in the past, and enable printing with good print quality without bleeding on plain paper. Have an effect.

Claims (2)

[Claims] 1. The dispersion medium is a non-polar insulating solvent,
In an inkjet printer ink in which at least a pigment is dispersed in the dispersion medium, the dispersed pigment has an average particle size in the range of 1.0 to 2.0 μm, and
In the range of 0 to 2.0 μm, 70% or more of the pigment having a particle size distribution dispersed is present, and in the range of 0.5 to 3.0 μm, the pigment having 90% or more of the particle size distribution being dispersed is present. An ink for an inkjet printer, which is characterized in that 2. The ink according to claim 1, wherein a resin and / or a dispersant is added to the ink composition.