JPH0525417A - Ink for ink jet printer - Google Patents

Abstract

PURPOSE:To prevent the blurring on a recording paper and clogging in a nozzle and to improve the drying properties and scratch resistance of printed characters by dispersing colored resin particles in a nonpolar insulating solvent. CONSTITUTION:A resin softened by heating is mixed with 1-30wt.% pigment having a particle diameter of 25mum or lower under heating and pulverized to give colored resin particles, which are dispersed in a nonpolar insulating solvent, if necessary contg. a dispersant dissolved therein, to give the objective ink having a viscosity of 30muPa.s or lower around a nozzle at 0-50 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink used 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, ink jet recording systems can be roughly classified into two types, that is, a continuous type and an on-demand type. As the ink used in such an ink jet system, an ink in which a dye is dissolved in water is predominant (hereinafter referred to as an aqueous ink). The water-based ink is currently used in which various water-soluble dyes are dissolved in water or a solvent composed of water and a water-soluble organic solvent, and various additives are added as necessary. The advantages of these inkjet recordings are that the process is simple because it is direct recording, there is no noise because it is not an impact method, colorization is easy, high-speed recording is possible, and plain paper can be used. Low running cost,
It has excellent features such as high-resolution recording because it ejects minute ink droplets, and its future is drawing attention.

[0003]

However, in the above-mentioned prior art, although a little different depending on the method, there are common technical problems: 1. The ink bleeds on the recording paper and a high-quality recorded image cannot be obtained.

The two inks are slow to dry on the recording paper and cause tailing.

[0005] Three nozzles and the ink supply path are clogged, and ink ejection is not stable.

Since the four inks have poor scratch resistance on the recording paper, the recorded image has no storability.

And the like.

Attempts have been made to solve the above problems. For example, in Japanese Patent Publication No. 55-29546, a specific surface active agent is added to lower the surface tension of an ink recording paper. It has been proposed that Japanese Patent Publication No. 56-57862 has a strongly basic substance added to increase the pH and chemically treats sizing agents and pulp agents which are water-resistant treatment agents for plain paper. A method of controlling the spread and absorption of dots by dissolving in water has been reported. In addition, Japanese Patent Publication No. 58-13675 discloses that polyvinyl pyrrolidone having a molecular weight of 40,000 or more is added to the ink to spread the dots and recording paper. Although a method of controlling the absorbability of the above has been proposed, these attempts have solved some of the above problems, and are not a measure for solving all the problems.

Therefore, an object of the present invention is to provide an ink for an ink jet printer which is free from bleeding on recording paper, has excellent printing dryness, has no nozzle clogging, and has excellent scratch resistance. ..

[0010]

The ink for an ink jet printer of the present invention is characterized in that colored resin particles are dispersed in a dispersion medium which is a nonpolar insulating solvent.

[0011]

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. A predetermined amount of pigment is added to a softened state by heating the resin, and the resin is colored by kneading with a three-roll while heating. At this time, a dye may be added to enhance the color developability. Crush this,
After adjusting the particle size, the particles are dispersed in a dispersion medium which is a nonpolar insulating solvent. In addition, a dispersant is added if necessary during dispersion. The method for producing the ink of the present invention is not limited to this.

Examples of the resin that can be used in the present invention include phenol resin, amino resin (urea resin, melamine resin), diallyl phthalate resin, epoxy resin, unsaturated polyester resin, silicone resin, polyurethane, polyimide, BT resin. , Polyamideimide, high density polyethylene, ultra high molecular weight polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, polymethylpentene, polystyrene, AB
S resin, AS resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl formal, methacrylic resin, fluororesin, polycarbonate, polyacetal,
Nylon 6,6-6, flexible nylon, aromatic polyamide (aramid), PET, PBT, modified PPO, polyphenylene sulfide, polysulfone, polyether sulfone, polyether ether ketone, polyarylate,
Aromatic polyester (Econol), cellulose acetate,
Polyvinyl acetate / cellulose acetate butyrate, styrene-maleic acid copolymer, benzyl sulfose, ethyl cellulose, natural rubber, nitrocellulose, ketone resin, polymethylmethacrylate, polyamide resin,
Acrylonitrile-styrene copolymer, vinylidene chloride-acrylonitrile copolymer, hydroxypropyl cellulose, vinyl chloride-vinyl acetate copolymer, shellac,
Vinyl chloride-vinyl acetate copolymer, polyester, polyacrylic acid ester, cellulose acetate propionate, cellulose acetate butyrate, polyvinylpyrrolidone, vinyl acetate butyl copolymer, hydroxypropylmethylcellulose phthalate, polyurea and the like. The required properties are any resin that is insoluble in the non-polar insulating solvent, and the resin suitable for the above manufacturing method is preferably thermoplastic.

The pigment used for coloring the resin in the present invention is not particularly limited. For example, for black and white, carbon black such as furnace black, lamp black, acetylene black and channel black, or copper, Examples include metals such as iron and titanium oxide, metal oxides, and organic pigments such as ortho-nitroaniline black. For color, Toluidine Red, Permanent Carmine FB, Fast Yellow AA
A, disazo orange PMP, lake red C, brilliant carmine 6B, phthalocyanine blue, quinacridone red, dioxane violet, pictoria pure blue, alkali blue toner, fast yellow 10G, disazo yellow AAMX, disazo yellow AA
OT, disazo yellow AAOA, 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 lysosome red, pigment scar red 3B rake, rake bordeaux 10B, anthocin 3B rake, anthocin 5
B rake, Rhodamine 6G rake, Eosin rake, Bengal, Fafthor red FGR, Rhodamine B rake, Methyl violet red rake, Dioxazine violet, Basic blue 5B rake, Basic blue 6G rake, Fast sky blue, Alkali blue R
Toner, Peacock Blue Rake, 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 Flower , 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 carmine F
B, Fastello G, disazo yellow AAA, disazo orange PMP, lake red C, dioxane violet red, alkali blue G toner and the like, and other processed pigments such as graft carbon whose pigment surface is treated with resin or the like can be used. The addition amount is preferably 1 to 30% by weight,
Further, 3 to 12% by weight is preferable. A pigment is used with a particle size of 25 μm or less, but it is 0.1 because of high printing quality, storage stability, and difficulty in clogging at the discharge nozzle.
It is preferable to use a pigment composed of particles of ˜5 μm or less.

The dye added in the present invention to enhance the color developability of the resin particles can be selected from the following dyes and used. For example, acridine dye, aniline black dye, anthraquinone dye, azine dye, azomethine dye, benzo- and naphthoquinone dye, indigoid dye, indophenol dye, indoaniline dye, indamine dye, leuco dye, naphthalimide dye, nigrosine dye, indulin dye, nitro. Further, dyes such as nitroso dyes, oxazine and dioxazine dyes, oxidation dyes, phthalocyanine dyes, polymethine dyes, quinophthalone dyes, sulfur dyes, tri- and diacrylmethane dyes, thiazine dyes, thiazole dyes, xanthene dyes, cyanine dyes can be used.

The pigments and dyes described above can be used in combination as the coloring material of the present invention.

The dispersion medium that can be used in the present invention is a nonpolar insulating solvent such as an aliphatic hydrocarbon solvent, specifically Isopar (exxon company), Soltor (Philips Oil Company), IP (Idemitsu Petrochemical Company). For solvent and petroleum naphtha, Shell Petrochemical Co. B. R. , Shelsol, Pegasol of Mobil Oil Co., and the like. The required properties are low toxicity, low flammability, and low odor.

When the resin particles colored according to the present invention are dispersed in a dispersion medium, a dispersant can be used if necessary. Dispersants that can be used include nonionic activators, cationic activators, and anionic activators. 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.
As the cation activator, octadecylamine acetate,
Alkyl (hardened tallow) trimethylammonium chloride, polyoxyethylene octadecylamine, etc. are available.
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 fine particles.

Ink viscosity, which is a physical property required for an ink for an ink jet printer, is the stability of ink droplet formation under high speed response of the head when the temperature of the printing device is set to 0 to 50 ° C. From the viewpoint of flight stability, 30 mPa.
It is necessary to be s or less, and 1.0 to 15 mPa · s is more preferable in order to realize even faster response.

The components of the ink will be specifically described below.

Table 1 shows the ink composition of the example according to the present invention and the ink composition of the comparative example (water-based ink).

[0022]

[Table 1]

The ink composition of the comparative example shown in Table 1 is almost the same as the commercially available water-based ink.

After the ink having the composition shown in Table 1 was prepared, the following evaluation items were provided to evaluate the ink for ink-jet printer of the present invention and the ink of Comparative Example.

Print quality: After printing on various transfer papers,
The presence or absence of ink bleeding was evaluated visually or by microscopic observation (60 times), and bleeding could not be confirmed by visual or microscopic observation.・ ・ ・ Suitable (⊚) ・ Bleeding cannot be visually confirmed, but can be confirmed by microscopic observation.・ ・ ・ Appropriate (○) ・ Bleeding can be confirmed by both visual observation and microscopic observation. ... Classified and evaluated by unsuitability (x). The results are shown in Table 2.

Printing Dryness: After full solid printing, another recording paper is aligned with the printing surface and the time until the ink does not transfer is investigated, and the ink does not transfer within 5 seconds.・ ・ ・ Satisfactory (⊙) ・ No ink transfer within 60 seconds.・ ・ ・ Appropriate (○) ・ It takes 60 seconds or more before ink transfer stops. ...
It was classified and evaluated according to unsuitability (x). The results are shown in Table 2.

Ink clogging: A commercially available inkjet printer head is filled with ink and left in a 40 ° C. environment without a nozzle for a week to evaluate the ink ejection status. Immediate ejection ... Suitable (◎) ・ Rubbing with a rubber plate Discharge: Suitable (○) ・ No discharge. ... Classified and evaluated according to unsuitability (x). The results are shown in Table 2.

Persistence resistance: After full solid printing, the printed matter is completely dried, and then the printed portion is rubbed with a finger to the recording paper.・ ・ ・ Suitable (⊚) ・ Stain can be visually confirmed. ... Classified and evaluated according to unsuitability (x). The results are shown in Table 2.

[0029]

[Table 2]

The ink for an ink jet printer of the present invention has a high print quality without bleeding in the evaluation conducted this time, has a fast drying speed on the recording paper, and has a good result in the clogging test of the ink nozzle. The result was excellent in the scratch resistance test, and was preferable as an ink for an inkjet printer. On the other hand, the inks of Comparative Examples were less likely to cause clogging, but were unsuitable as inks for inkjet printers in print quality, print dryness, and scratch resistance.

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.

[0032]

As described above, according to the ink for an ink jet printer of the present invention, there is no bleeding on plain paper, which has been a problem in the past, excellent print drying property, no nozzle clogging, and scratch resistance. It has an excellent effect.

Further, according to the ink for an ink jet printer of the present invention, since it is excellent in high printing quality, high density, ink drying property on recording paper, clogging resistance and abrasion resistance, a page printer and a color printer ( Multiple colors,
It can also be used for high-speed page printers that use a line head.

Claims (1)

Claim: What is claimed is: 1. An ink for an ink jet printer, characterized in that colored resin particles are dispersed in a dispersion medium which is a nonpolar insulating solvent.