JP3385802B2 - 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 a recording liquid for ink jet recording and writing instruments.

[0002]

2. Description of the Related Art In an ink jet recording method, when plain paper such as electrophotographic paper, bond paper, and stock foam paper is used as recording paper, the water resistance after printing is inferior, or the density of printed matter (hereinafter referred to as " There is a problem that the storage stability of the ink tends to become unstable in addition to the problem that the "OD" is abbreviated). Therefore, it has been studied to reduce the water solubility of the dye in order to improve the water resistance or to introduce a hydrogen-bonding amino group or the like into the dye structure. As a result, a phenomenon called so-called "bronzing" occurs, in which the aggregate of the pigment has a piece of gloss on the paper, and the OD of the printed matter decreases, or the pigment aggregates during storage of the ink, There is a problem of precipitation.

As one of the means for solving these problems, it has been proposed to incorporate a certain nitrogen-containing compound in the recording liquid. As an example of this, Japanese Patent Laid-Open No. 54-797
28, JP-A-55-120676, JP-A-2-41
No. 369, JP-A No. 62-119280, and JP-A No. 5-1.
No. 25311, JP-A-1-152176, and JP-A-64
The inventions described in JP-A-6072, JP-A-6-128515 and the like are known, but these recording liquids fail to obtain sufficient effects or fail to obtain the effects with respect to the above problems. Also has major defects such as easy clogging at the nozzle tip or bleeding of printing.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording liquid which has a high print OD even when recording on plain paper and is excellent in water resistance.

[0005]

The present invention provides a water-soluble dye,
An aqueous medium, and a weight average molecular weight of 2,000 to 30,
The gist is a recording liquid containing a polyamino acid of 000 and / or a salt thereof. Hereinafter, the present invention will be described in detail. The water-soluble dye used in the present invention is not particularly limited, and azo-based, anthraquinone-based, quinophthalone-based, indigo-based and phthalocyanine-based direct dyes and acid dyes, and dyes developed for recording liquids can of course be used. For example, C.I. I. Direct Black-17,
-19, -22, -32, -51, -80, -91,-
151, -154, -168 and -195, C.I. I. D
direct Blue-86 and -199, C.I. I. D
direct Red-80, C.I. I. Direct Y
ellow-86 and -142, C.I. I. Acid B
rack-2, -24, -26, -48, -52, -6
3, -172, -194 and -208, C.I. I. Aci
d Blue-9, -185 and -254, C.I. I. A
cid Red-8, -35, -37 and -257,
C. I. Acid Yellow-23 and -49 and C.I. I. Food Black-2 etc. are mentioned.

The content of the water-soluble dye is usually in the range of 0.2 to 12% by weight, preferably 2 to 8% by weight, based on the total weight of the recording liquid. Examples of the aqueous medium used in the present invention include, in addition to water, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycols such as glycerin, N-methyl-pyrrolidone, N-ethyl-pyrrolidone. , N-vinyl-pyrrolidone, 1,3-dimethyl-imidazolidinone, ethylene glycol monoallyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, and other ethers, 2-pyrrolidone, sulfolane, ethyl alcohol, isopropanol It contains water-soluble organic solvents such as alcohols such as alkanolamines such as diethanolamine and triethanolamine. Preferred, the content of these water-soluble organic solvent, the recording liquid to the total weight, and in the range of 10 to 50 wt%. On the other hand, the amount of water used is in the range of 45 to 90% by weight based on the total weight of the recording liquid.

The recording liquid of the present invention has a weight average molecular weight of 2,000 to 30,000, preferably 3,000 to 2.
Characterized by the use of polyamino acids and / or salts thereof in the range of 10,000. Weight average molecular weight of 2,000
If it is smaller, the effect on water resistance is not sufficient and 30,
If it is more than 000, the penetrability into the ink paper is increased, the bleeding is increased, the printing quality and the OD are lowered, and the ejection becomes unstable.

The polyamino acid and / or its salt used in the present invention is preferably water-soluble. Examples of the main component monomer constituting the polyamino acid include acidic amino acids (aspartic acid, glutamic acid, etc.), basic amino acids (lysine, etc.), etc., but acidic amino acids are preferable, and aspartic acid is particularly preferable. Examples of the polyamino acid include those polymerized in a linear chain or those polymerized in a branched chain, but a linear chain is preferable. In the following, particularly preferred polyaspartic acid and / or
Alternatively, the present invention will be described in detail by taking the case of a salt thereof as an example.

The content of polyaspartic acid and / or its salt is usually in the range of 0.2 to 5% by weight, preferably in the range of 0.5 to 2% by weight, based on the total weight of the recording liquid.
Examples of the polyaspartic acid salt include ammonium salts, alkali metal salts and organic amine salts, with ammonium salts being particularly preferred. Incidentally, polyaspartic acid and its salt can be produced by hydrolyzing polysuccinimide which is a precursor thereof. Polysuccinimide is, for example, a method of reacting aspartic acid or maleamic acid in a solid phase at a high temperature of 180 ° C. or higher (US Pat. Nos. 5,057,597 and 5,2,5).
19,986, 5,315,010 or JP-A-6-206937), a method of reacting ammonia with maleic anhydride in a solid phase at a temperature of 120 ° C. or higher (US Patent Nos. 4,839,461 and 5,296,578, etc.), and aspartic acid or maleamic acid,
Known methods such as a method of reacting at a temperature of 120 ° C. or higher in the presence of a solvent such as polyethylene glycol, N-methylpyrrolidone or sulfolane (see JP-A-6-145350 or JP-A-6-211982) Alternatively, a reaction product obtained from maleic acid and ammonia, maleamic acid or aspartic acid is selected from the group consisting of aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents and aprotic polar solvents. To produce a polysuccinimide by reacting in a solvent having a boiling point of 100 ° C. or higher (Japanese Patent Application No.
-318638, Japanese Patent Application No. 7-51558, etc.) or a mixture of aspartic acid and an acid catalyst in a reactor,
Examples thereof include a method of reacting while heating or stirring or kneading (see Japanese Patent Application No. 7-43116).

Further, the polyaspartic acid may be a copolymer in which other monomers other than aspartic acid are used within a range not exceeding 50 mol%. Examples of these copolymerizable monomers are a) glutamic acid and salts thereof, b) aspartic acid such as alanine, leucine and lysine, amino acids other than glutamic acid, c) hydroxycarboxylic acid such as glycolic acid, lactic acid and 3-hydroxybutyric acid. , D) compounds having two or more functional groups capable of reacting with amino groups and / or carboxyl groups such as ethylene glycol and maleic acid.

The pH of the recording liquid of the present invention is usually adjusted to 8 to 10 using alkali or the like. Further, the recording liquid of the present invention contains 0.1 to 10% by weight, preferably 0.5 to 5% by weight, of a compound selected from urea, thiourea, biuret and semicarbazide, or 0% by weight based on the total weight of the recording liquid. .0
By adding the surfactant in an amount of 01 to 0.5% by weight, the quick drying property after printing and the printing quality can be further improved.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Production Example of Polyaspartic Acid (Production Example 1) 100 g of L-aspartic acid and 85%
3 g of phosphoric acid was charged into a mixer (Oster blender) and mixed at room temperature for 15 minutes to obtain a mixture. Then, the mixture obtained above was charged into a four-neck decomposition flask equipped with a condenser, a thermometer and a stirrer, and the polycondensation reaction was started under a nitrogen stream while heating with a mantle heater. Since water began to distill off when the internal temperature was around 160 ° C, the reaction was started at this point and the temperature was raised to 200 ° C in 30 minutes.
Further, the mixture was stirred at the same temperature for 1 hour to obtain 73.2 g of a pale yellow polysuccinimide powder. The weight average molecular weight of this polysuccinimide was 9,900.

The weight average molecular weight is a product of Tosoh Corporation, trade name, TSKgel GMHHR-M column and TS.
10m for Kgel G2000HHR column and eluent
It is a polystyrene conversion value obtained by a GPC chromatograph (differential refractometer) using dimethylformamide of MLiBr. Moreover, hydrolysis was performed with a stirring bar.
A 0 cc beaker was charged with 6 g of the polysuccinimide obtained above and 20 g of water, and an aqueous solution in which 2.8 g of sodium hydroxide was dissolved in 20 g of water was added under ice cooling, and then 1
It is performed by stirring for an hour, and then p
It was made H2 and crystallized by pouring the reaction solution into 300 ml of methanol to obtain 6.1 g of white polyaspartic acid. (Compound No. 1)

(Production Example 2) 100 g of L-aspartic acid
And 10 g of 85% phosphoric acid were charged in a mixer (Oster blender) and mixed at room temperature for 15 minutes to obtain a mixture. Then, in a four-neck decomposition flask equipped with a condenser, a thermometer and a stirrer, the mixture obtained above is charged,
The polycondensation reaction was started under a nitrogen stream while heating with a mantle heater. Since water began to be distilled off at an internal temperature of around 160 ° C., the reaction was started at this point, the temperature was raised to 200 ° C. in 30 minutes, and the mixture was further stirred at the same temperature for 1 hour to obtain a pale yellow polysuccinimide powder 71. 0.4 g was obtained. The weight average molecular weight of this polysuccinimide was 17,000. The hydrolysis was performed in the same manner as in Production Example 1 to obtain 6.3 g of white polyaspartic acid. (Compound N
o. 2)

(Production Example 3) In a 500 mL four-necked flask equipped with a condenser, a thermometer, a stirrer and a water separator,
200 g of aspartic acid was charged. Then, under reduced pressure (1
0 hP), the polycondensation reaction was carried out by heating with a mantle heater for 6 hours so that the internal temperature was 200 ° C., and 123.7 g of a brown-colored polysuccinimide was obtained. The weight average molecular weight of this polysuccinimide was 4,900. The hydrolysis was performed in the same manner as in Production Example 1 to obtain 4.8 g of white polyaspartic acid. (Compound No. 3)

Example 1

[Table 1]             Composition of recording liquid Usage (% by weight)   C. I. Food Black-23   Diethylene glycol 10   The No. Na salt of compound 2 1.5   Water balance ────────────────────────────────────           Total 100

The above components were sufficiently mixed and dissolved in a container, filtered under pressure with a Teflon filter having a pore size of 1 μm, and then deaerated using a vacuum pump to prepare a recording liquid.
The obtained recording liquid was used to perform inkjet recording with an inkjet printer (trade name; HG-3000, manufactured by Epson Corporation), and quick-drying property and print quality were evaluated according to the following methods (a) and (b). .

(A) Quick-drying: Printing is performed on electrophotographic paper (product of Xerox Co., Ltd.), bond paper and stock form paper (product of Lion Office Equipment Co., Ltd.), and after 30 seconds, the printing portion is rubbed with a finger to prevent misalignment of the image. The presence or absence was judged. All of them showed no deviation and showed excellent fixability. (B) Print quality: Each dot printed on the above recording paper was observed with a microscope, and the presence or absence of feathering (whisker-like bleeding) around the dot and the sharpness of the contour were visually evaluated. Both have no feathering,
The contour was also sharp.

Further, ink jet recording was evaluated according to the following methods (c) to (f). (C) Long-term storability of recording liquid: After the recording liquid was sealed in a glass container and stored at 0 ° C. and 60 ° C. for 6 months, no precipitation of insoluble matter was observed, and the physical properties and color tone of the liquid did not change. There wasn't. (D) Ejection stability: Continuous ejection was performed for 24 hours in each of the atmospheres at room temperature, 5 ° C., and 40 ° C., and stable high-quality recording was always possible under any of the conditions.

(E) Discharge responsiveness: intermittent discharge every 2 seconds and 2
The discharge after leaving for a month was examined, and in each case, the orifice tip was not clogged, and stable and uniform recording was performed. (F) Quality of recorded image: The recorded image was high in density and clear. The rate of decrease in density after exposure to room light for 3 months was 10% or less, and when the film was immersed in water for 1 minute, image bleeding was extremely slight.

Comparative Example In Example 1, the No. Evaluation was carried out in the same manner as in Example 1 except that the compound of 2 was not added. As a result, when the formed image was immersed in water for 1 minute, the recorded image was remarkably blurred and the density was remarkably low. .

Example 2

[Table 2] Composition of recording liquid Amount used (% by weight) C.I. I. Direct Blue-86 3 Glycerin 10 Ethylene glycol 10 Said No. NH ₄ salt of compound 1 1 Water residual amount ─────────────────────────────────── Total 100

A recording liquid having the above composition was prepared in the same manner as in Example 1, and the results of (a) to (f) were examined. As a result, good results were obtained. Examples 3 to 14 According to the method of Example 1, recording liquids having the compositions shown in Table 1 below were prepared, and (a) to (f) described in Example 1 were prepared.
As a result of evaluation according to the above method, all were good.

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

[Table 6]

[0028]

[Table 7]

[0029]

INDUSTRIAL APPLICABILITY The recording liquid of the present invention is used for ink jet recording, writing instruments, etc., and is excellent in quick-drying property after recording and printing quality. No rubbing of the image even if rubbed, and
An image with no bleeding and a sharp contour can be obtained. When the recording liquid of the present invention is used for inkjet recording, in addition to the above effects, recording characteristics (signal responsiveness, droplet formation stability, ejection stability, long-term continuous recording property), storage stability Also, the OD of recorded images, light resistance, weather resistance, water resistance, etc. are all good.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Nakato 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi Chemical Corporation Tsukuba Research Laboratory (56) Reference JP-A-59-53565 (JP, A) ) JP-A-4-16476 (JP, A) JP-A-7-150084 (JP, A) JP-B 31-4321 (JP, B1) JP-A 8-507100 (JP, A) International Publication 95/27759 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09D 11/00-11/20 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A recording liquid containing a water-soluble dye, an aqueous medium, and a polyamino acid having a weight average molecular weight of 2,000 to 30,000 and / or a salt thereof. 2. The recording liquid according to claim 1, wherein the polyamino acid is polyaspartic acid. 3. The recording liquid according to claim 1, wherein the polyamino acid and / or its salt has a weight average molecular weight of 3,000 to 20,000.