JPH06256694A - Recording ink - Google Patents

Abstract

PURPOSE:To prepare a recording ink which dries quickly on a plain paper and gives a colored printing free from blur by compounding a water-sol. dye, a water-sol. org. solvent, and an alkali metal salt of polycarboxymethyl-N- acetylglucosamine. CONSTITUTION:An alkali metal salt of polycarboxymethyl-N-acetyglucosamine is obtd. by carboxymethylating poly-N-acetylglucosamine in an alkali soln. and precipitating the resulting product at the alkali side. A recording ink is prepd. by compounding 0.2-12 pts.wt. water-sol dye, 1-50 pts.wt. water-sol. org solvent, 0.01-1 pt.wt. alkali metal salt of polycarboxymethyl-N- acetylglucosamine, 0.001-5 pts.wt. surfactant of the formula (wherein R is an optionally branched 6-14C alky group; M is an alkali metal ion, a quaternary ammonium, a quaternary phosphonium, or an alkanolamine; and (n) is 3-12) if necessary, and water in such an amt. that the total amt. is 100 pts.wt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording ink for ink jet recording and writing instruments.

[0002]

2. Description of the Related Art Ink jet printers have characteristics such as low noise, low running cost, and easy color recording, and have been rapidly spread in recent years as digital signal output devices. As a recording ink for such an ink jet printer, various materials such as an ink mainly composed of an aqueous dye, an ink mainly composed of an oily dye, a pigment-dispersed ink and a solid ink capable of being melted by heat have been proposed. Among them, water-based inks, which mainly consist of water-based dyes, are the most suitable for society's demands for conservation of the global environment, from the viewpoints that the ink materials are highly safe for the living body and the environment, and the energy consumption of the printer is small. It is considered to be a method.

The properties required for ink jet inks mainly composed of such aqueous dyes are as follows: 1) Generally used in offices and homes such as copy paper, report paper, bond paper and foam paper. Even non-coated paper, so-called plain paper, can be printed quickly without bleeding, and 2) there is no bleeding at pixel boundaries during color overprinting. 3) Water resistance 4) Excellent, when filled in the head, the head nozzle is not clogged even if left for a long time, and the reliability is high.

Aqueous inks of various compositions have hitherto been proposed in order to satisfy the above-mentioned required performance. For example, in order to improve the reliability of the ink, the water-based ink generally contains a water-soluble high-boiling point organic solvent such as glycerol. However, when printing is performed on plain paper having a high degree of size with such an ink, there is a problem that the permeation speed of the ink in the paper thickness direction is slow and the dry portion of the printing portion is bad. At that time, the image quality is significantly deteriorated.

In order to enhance the ink permeability in the paper thickness direction, for example, Japanese Patent Laid-Open No. 55-29546 proposes a method of adding a large amount of a surfactant to the ink.
In this case, there are problems that bleeding occurs very much depending on the paper, and when the ink jet head is filled with ink, the ink is not ejected depending on the material and structure of the head.

Further, Japanese Patent Application Laid-Open No. 1-213376 proposes a technique for making the pH of the ink strongly alkaline in order to improve the ink fixing property to paper and the water resistance. In this case, in addition to the safety to the living body, there is a problem that the fixing property and the water resistance are not sufficient for neutral paper, for example.

Further, for the purpose of improving the bleeding of the ink, the drying property of the printed matter, and the clogging property of the head, for example, JP-A-3-259967 proposes a technique of containing an alkyl ether of polypropylene glycol in the ink. Has been done. In this case, the image quality of color ink overprinting is not always satisfactory. As described above, various techniques have been proposed in addition to the above, but an ink that sufficiently satisfies the required performance has not been known so far.

[0008]

An object of the present invention is to obtain a drying time for so-called plain paper, which is uncoated paper generally used in offices and homes such as copy paper, report paper, bond paper, and foam paper. It is an object of the present invention to provide a recording ink that is capable of high-speed color printing with high quality without blurring. Another object of the present invention is to provide a highly reliable ink with improved nozzle clogging when applied for ink jet recording.

[0009]

The constitution of the present invention for solving the above problems is a recording ink containing a water-soluble dye, a water-soluble organic solvent and a metal salt of polycarboxymethyl-N-acetylglucosamine. .

As a raw material of the alkali metal salt of polycarboxymethyl-N-acetylglucosamine, chitin can be mentioned. Chitin is a polysaccharide represented by β-poly-N-acetyl-D-glycosamine, but it is almost insoluble in water and other solvents due to the strong hydrogen bond between molecules.

Polycarboxymethyl-N used in the present invention
The alkali metal salt of -acetylglucosamine is a compound obtained by carboxymethylating chitin, that is, poly-N-acetylglucosamine in an alkaline solution, and then depositing on the alkaline side.

As an example of the production method, when poly-N-acetylglucosamine is dissolved in an alkaline solution, poly-N-
-Acetylglucosamine with alkaline solution mixture-10
After freezing at around 0 ° C and thawing at 0-5 ° C,
An alkaline solution of poly-N-acetylglucosamine can be obtained without a decrease in the molecular weight or a by-product of deacetylation. As the alkaline solution used in this method, aqueous solutions of sodium hydroxide, potassium hydroxide and other alkali metal salts are generally used.

The amount of the metal salt added is 1 to 10 times equivalent to poly-N-acetylglucosamine as a metal salt, preferably 5 times.
~ 8 times equivalent. Next, 1 to 8 times equivalent, preferably 3 to 5 times equivalent of monochloroacetic acid is reacted as a carboxymethylating agent to obtain an alkali metal salt solution of polycarboxymethyl-N-acetylglucosamine.

To this, an acid, for example, hydrochloric acid is added to adjust the pH at the isoelectric point.
Precipitation on the alkali side of 9 or more gives a solid alkali metal salt. Examples of the alkali metal salt include sodium salt, potassium salt and lithium salt, but are not particularly limited. The structural formula of the sodium salt of the compound is shown in Formula I. In this formula, n is 200 to 4,000.

[0015]

[Chemical 1]

The weight ratio of the alkali metal salt of polycarboxymethyl-N-acetylglucosamine of the present invention to be mixed with the recording ink is in the range of 0.01 to 1 part by weight per 100 parts by weight of the recording ink. Since the compound has a high solubility in water and a large amount of equilibrium water content, it is considered that the recording ink containing the compound does not cause clogging of the head nozzles due to evaporation of water and has high reliability. Furthermore, since this compound has an appropriate viscosity-improving property, it is considered that there is no undesired mixing of the ink at the pixel boundary even in the case of multicolor printing, and high quality image is provided.

In the present invention, it is desirable to further contain a surfactant. Examples of the surfactant applicable to the present invention include conventionally known anionic, cationic, nonionic and amphoteric compounds.

Examples thereof include polyoxyethylene alkyl ether compounds, oxyethylene-containing acetylene diol compounds, dialkyl sulfosuccinic acid ester compounds, fluorine compounds and silicone compounds. A particularly preferred surfactant is a compound represented by the following structural formula II.

Structural formula II R—O— (CH ₂ CH ₂ O) _m CH ₂ COOM (wherein R: an alkyl group having 6 to 14 carbon atoms which may be branched, m: an integer of 3 to 12, M: Represents an alkali metal ion, quaternary ammonium, quaternary phosphonium, or alkanolamine).

The content of these surfactants in the recording ink is 0.001 to 5 parts by weight, preferably 0.01 to 2 parts by weight, per 100 parts by weight of the ink. By adding a surfactant, the ink permeation speed in the thickness direction of the paper can be increased and the quality of the printed image can be further improved.

As the water-soluble dye used in the recording ink of the present invention, conventionally known acid dyes such as azo, anthraquinone, indigo, triphenylmethane and phthalocyanine, basic dyes, reactive dyes, edible Examples include dyes.

Specific examples of applicable dyes include C.I. I. Direct Black-17, -19, -22,22
-32, -51, -80, -91, -151, -154
And -168, C.I. I. Direct Blue-86 and -199, C.I. I. Direct Red-9 and -227, C.I. I. Direct Yellow -86, -132 and -1
42, C.I. I. Acid Black-2, -24, -26, -4
8, -52, -63, -172, -194 and -20
8, C.I. I. Acid blue-9,185 and -249, C.I. I. Acid Red-8, -35, -37, -5
2, -92, -94, -254 and -289, C.I. I. Acid Yellow-23 and -49, C.I. I. Reactive Black-31, C.I. I. Reactive Red-23 and -180, C.I. I. Reactive Yellow-37, C.I. I. Food Black-2 etc. are mentioned.

The amount of the water-soluble dye compounded in the recording ink is 0.2 to 12 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the ink.

Water-soluble organic solvents applicable to the recording ink of the present invention include methanol, ethanol, n-propanol, isopropanol, n-butanol and sec.
-Alkyl alcohols such as butanol, tert-butanol, isobutanol, isoamyl alcohol;
Amides such as formamide, dimethylformamide, dimethylacetamide; dimethyl sulfoxide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene Glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, 1,3-butanediol 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,5-hexanediol, 3-methyl-1,3
-Butanediol, 2-methylpentane-2,4-diol, 3-methylpentane-1,5-diol, 1,
2,3-butanetriol, 1,2,4-butanetriol, 3-methylpentane-1,3,5-triol,
Alkylene glycols such as 1,2,6-hexanetriol; glycerols such as glycerol, diglycerol and triglycerol; thiodiethanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol Lower alkyl ethers of glycols such as mono-n-butyl ether; N-methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone; triethanolamine; sulfolane and the like.

The amount of these water-soluble organic solvents added to the recording ink is preferably 1 to 50 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the ink. The above water-soluble organic solvents can be used alone or as a mixture of two or more kinds. In addition, the recording ink of the present invention may contain a pH adjusting agent, an antibacterial / antifungal agent, a sequestering agent, etc., if necessary.

[0026]

EXAMPLES Next, examples of the present invention and comparative examples will be specifically described. All blending amounts are% by weight. Example 1 C.I. I. Direct Black 168 3.0% Diethylene glycol 7.5% Glycerol 2.5% Polycarboxymethyl-N-acetylglucosamine Na salt 0.2% Ion-exchanged water 86.8% Polycarboxymethyl-N-acetylglucosamine Na
After the salt is completely dissolved in ion-exchanged water, all the remaining components are added and completely dissolved. Next pore diameter 0.45 μm
After being pressure-filtered by a membrane filter having No. 1 and then deaerated using a vacuum pump, a recording ink of this example was prepared. The present embodiment corresponds to claim 1.

Examples 2 to 18 According to the method described in Example 1, a recording ink of this example having the description in Table 1 below was prepared.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

Comparative Examples 1 to 4 According to the same procedure as in Example 1 except that polycarboxymethyl-N-acetylglucosamine Na salt was not used in Example 1, the recording ink of this Comparative Example was formed according to the following Table 2. Was prepared.

[0032]

[Table 4]

The prepared recording inks of Examples and Comparative Examples of the present invention were subjected to single-color color printing and color-color overprinting using a known ink jet printer (Desk Writer C, manufactured by Hewlett-Packard Company, USA). , (A) drying time and (B) print quality in single color printing, and (C) print quality in color overprinting were evaluated.

(A) Ink Drying Time Reprint Type 6200 paper (high-quality paper), Fuji Xerox R paper (recycled paper) and Gilbert Bond paper (bond paper), the solid portion printed on the filter paper is pressure-bonded to the filter paper. The time at which transfer was stopped was evaluated and classified by: less than 5 seconds ◎ 5 to 15 seconds ○ 16 to 30 seconds Δ 31 seconds or more ×.

(B) Printing quality according to paper type Each dot printed on the above recording paper is observed under a microscope, and uneven bleeding around the dots (feathering) and uniform bleeding (sharpness of outline of dots) The results were evaluated by visual observation and classified as bleed-free ◎ almost no bleeding ○ bleeding △ bleeding ×.

(C) Print quality by color overprinting Color overprinting was performed on the above-mentioned recording paper using cyan, magenta and yellow inks, and ink bleeding and sharpness at the color overprint boundary were visually evaluated, and bleeding was performed. None ◎ Almost no bleeding ○ Bleeding is present △ Large bleeding × Next, the reliability of the ink was evaluated by the following method.

(D) Reliability of ink Ink is filled in a cartridge of a known ink jet printer (HG-3000, manufactured by Seiko Epson Co., Ltd.) and left for 1 month in an environment of 40 ° C. and 30% RH without a nozzle cap. Printing is performed later and printing is possible immediately. ○ Printing is possible by circulating ink and cleaning.

The evaluation results of the recording inks of Examples and Comparative Examples of the present invention by the above method are shown in Table 3 [Evaluation (A),
(B) and (D)], and Table 4 [Evaluation (C)].
Shown in.

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

As described above, when the recording ink of the present invention is used for ink jet or writing,
It is excellent in dryness and printing quality after recording and can give a high-quality printed image without blur to so-called plain paper such as copy paper, report paper, bond paper, and foam paper.

In particular, when multicolor color ink jet recording is carried out using the recording ink of the present invention, a high-quality multicolor color printed image can be obtained without unwanted bleeding of the ink at the boundary portion of the color overlapping pixels. Furthermore, it has a highly reliable performance that does not cause clogging even if left in the cartridge for a long time.

Claims (3)

[Claims] 1. A recording ink comprising a water-soluble dye, a water-soluble organic solvent, and an alkali metal salt of polycarboxymethyl-N-acetylglucosamine. 2. The recording ink according to claim 1, which contains a surfactant. 3. The recording ink according to claim 1, further comprising a surfactant represented by the following structural formula. _{R-O- (CH 2 CH 2} O) m CH 2 COOM ( wherein R is an alkyl group which may be branched having 6 to 14 carbon atoms; m is 3-12 integers; M is an alkali metal ion, 4 (Represents quaternary ammonium, quaternary phosphonium, and alkanolamine)