JPS63297477A - Ink for ink jet recording - Google Patents

Abstract

PURPOSE:To obtain the titled ink for recording, having excellent discharge stability and recording characteristics without causing clogging of nozzles for a long period, by containing a dicarboxylic acid diester and specific compound in a recording agent and liquid medium. CONSTITUTION:The aimed ink for recording, obtained by containing (B) (i) a dicarboxylic acid diester and (ii) a compound expressed by the formula (R1 is alkyl, aryl, heteryl, alkyloxy, aryloxy, heteryloxy, alkylamino, arylamino, arylalkylamino or heterylamino; R2 and R3 are H, alkyl, aryl or heteryl and not H at the same time; R1 and R2 and R2 and R3 together may form a ring) at 99.5/0.5-25/75 weight ratio and capable of satisfying liquid physical properties, such as viscosity.specific resistance, safety for human bodies and liquid composition stability while keeping high solubility.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an inkjet recording ink, and more particularly to an inkjet recording ink with excellent ejection stability and recording properties.

``Prior Art'' Inkjet recording methods include methods for generating recording liquid droplets, such as an ellipse, a pressure vibration type, a pressure/nucle type, and an electrostatic acceleration type. In each of these methods, a desired recorded image is obtained by ejecting fine ink droplets from an ink ejection port while controlling the size, number, ejection direction, etc. of the droplets.

Therefore, if the liquid composition of the ink liquid changes over time, or if solid content in the ink liquid precipitates in the head, stable ejection of droplets will not be possible, and in some cases, nozzle clogging may occur. This causes a significant loss in the quality of recorded images. Currently, water-based inks that use water and water-miscible solvents as liquid media are mainly used as inkjet recording inks, but because the liquid medium evaporates relatively quickly, nozzle clogging occurs. This is a major drawback. In order to solve this problem, various efforts have been made in terms of ink composition and equipment, but the problem has not yet been completely solved. It is known that one method of solving clogging based on the ink composition is to reduce evaporation of the ink liquid medium by using a non-aqueous ink that uses a high boiling point organic solvent for the ink liquid medium.

For example, JP-A-10-141J// discloses that high-boiling aromatic hydrocarbon solvents and high-boiling aliphatic hydrocarbon solvents can be used as liquid media for inkjet inks. These solvents are good liquid media in terms of slow evaporation rate and relatively low toxicity to the human body, but on the other hand, they have the disadvantage of low dissolving effect on dyes and low contrast of recorded images. be.

Tokukai Show 3! The benzoic acid esters proposed in No. -2j4LJJ have good dye solubility, but have an aromatic odor.

In JP-A No. 7-317λ, alkylnaphthalenes are
It has been proposed as a liquid medium with little odor and low toxicity.

However, since this compound is a nonpolar solvent, the specific resistance value becomes significantly high when used as an ink liquid. If a large amount of a polar solvent such as benzyl alcohol, dimethyl formamide or diethylene glycol methyl ether is used as a resistivity adjuster in order to adjust the resistivity to an appropriate value, the resistivity of the ink liquid will tend to change over time. Liquid stability deteriorates. Mononisdel bath additives such as lauric acid esters and isopropyl myristate are also characterized by the ability to adjust their resistivity by adding a polar solvent, similar to alkylnaphthalene compounds. Phthalate esters used in JP-A No. 35, JP-A No. 6-47F, JP-A No. 5'-7/37, etc. are stable solvents with high boiling points and have no odor. It is known that the toxicity to the human body is low. However, inkjet recording inks that use phthalate ester alone as a liquid medium tend to have high specific resistance and viscosity values, resulting in a small amount of ejection when printing, and the density of the recorded image is also insufficient. do. It is sufficient to use a complete mixture of liquid media that can lower the specific resistance and viscosity values without lowering the dissolving ability of the dye, but it is quite difficult to select a low toxicity and odorless solvent.

``Problems to be solved by the invention'' This method maintains high solubility of the sea urchin dye while satisfying all aspects of liquid physical properties such as viscosity and specific resistance, safety for the human body, and liquid composition stability. It was very difficult to find the medium liquid.

The purpose of the present invention is to provide an inkjet recording ink (hereinafter referred to as recording liquid) that does not cause nozzle clogging for a long period of time and maintains good ejection stability. To provide a recording liquid with little odor.

Another objective is to provide a recording liquid that always gives sharp, contrasting images with stable density, and yet another objective is to provide a recording liquid that gives images with excellent water resistance. That's true.

"Means for Solving Problems" The purpose of this method is to create an inkjet recording ink mainly composed of a recording agent and a liquid medium, which contains a dicarboxylic acid diester and a compound represented by the following general formula (I). This is achieved by using an inkjet recording ink characterized by the following.

General formula (I) In the formula, RtU represents an alkyl group, an aryl group, a heteryl group, an alkyloxy group, an arylox/group, a heteryloxy group, an alkylamino group, an arylamino group, an arylalkylamino group, or a heterylamino group. However, the above groups include one or more alkyloxy groups, arylox7
group, aryl group, halogen atom, cyano group, nitro group,
May be substituted with O1 by an ester group, carbamoyl group, acyl group, acylamino group, sulfonyl group, sulfamoyl group, sulfonamide group, amine group, mono- or di-alkylamino group, arylamine group, arylalkylamino group or hydroxyl group .

R2 and R3 each represent a hydrogen atom, an alkyl group, an aryl group, or a heteryl group. Each of these groups may be substituted with the substituent described in R1. However, R2 and R
3 cannot be a hydrogen atom at the same time. Also R1 and R2
Alternatively, R2 and R3 may be combined to form a ring.

This ring contains a total of 7 nitrogen atoms! Or a 4-membered saturated heterocycle, or contains one nitrogen atom and one oxygen atom phonetic name! Or a 4-membered saturated heterocycle is preferred. R1 and R2 are straight chain, branched or cyclic alkyl groups with carbon number /~/j, R3
However, the number of carbon atoms is 2~1! Particularly favorable results are obtained when the alkyl group is a straight-chain, branched or cyclic alkyl group.

The recording liquid of the present invention comprises a liquid medium as a carrier for a recording agent, a recording agent for forming a recorded image, and additives added depending on the packaging to obtain desired characteristics. It is essential to use a diester compound of general formula (I) in combination. The compound represented by the general formula (I) is a colorless and stable compound that has the effect of maintaining the specific resistance value of the ink liquid at an appropriate value (described later). It has been found that when the compound represented by the general formula (I) is used in combination with a diester dicarboxylic acid, the solubility of the dye is synergistically improved. Since the amount of dye contained in the recording liquid can be increased, clear and high contrast images can be obtained.

In addition, by using the compound represented by the general formula (I) in combination, it is possible to maintain all the physical properties of the recording liquid, such as specific resistance and viscosity, at appropriate values, and it is possible to easily achieve the desired discharge amount and recorded image density. can be secured.

The recording liquid of the present invention exhibits excellent liquid stability with little change in liquid physical properties and liquid composition even if the liquid medium is opened and left in the air because the evaporation rate of the liquid medium is significantly slower than that of water. The dye does not precipitate even if the recording liquid is left for a long period of time. Therefore, the present invention provides good results in terms of ejection stability and long-term continuous recording performance. Further, the recording liquid of the present invention has low odor, low flammability, and low toxicity, and has desirable properties as an inkjet recording liquid. Furthermore, the image drawn with the recording liquid of the present invention has excellent water resistance without causing any water stains or stains.

The dicarboxylic acid diester compound used in the present invention is
Generally well-known aliphatic dicarboxylic acid diesters or/or aromatic dicarboxylic acid diesters can be used (rIndustrial 5
olvents Handbook (Ilrd Ed
ition) J E, W, Flick edition NO YES
DATA C0RPORATION / P1j
Is the boiling point higher than 710C? ! Particularly preferred are compounds that are liquid at room temperature. Examples of such compounds include those described in Japanese Patent Application No. 61-211252. Specifically, the following compounds can be used, but are not limited to: diethyl malonate, dipropyl malonate, diethyl diethyl malonate, diethyl cononate, dibutyl succinate, dimethyl glutarate,
Diethyl glutarate, diethyl adipate, di(n)propyl adipate, diisopropyl adipate, dibutyl adipate, di(2-methoxyethyl) adipate
, diethyl pimelate, diethyl azelaate, diethyl sepacate, dibutyl sepacate, diethyl maleate, dibutyl maleate, maleic rR di(2-ethylhexyl), dibutyl fumarate, dibutyl mesaconate,
Dibutyl citraconate, dibutyl glutaconate, dimethyl phthalate, diethyl phthalate, di(n)propyl phthalate, diisopropyl phthalate, di(n) phthalate
butyl, diisobutyl phthalate, etc. These may be used alone or in combination with the compound represented by the general formula (I).

Specific examples of the compound represented by the general formula (I) of the present invention are shown below, but the invention is not limited thereto.

Compound 1 Compound co-Compound 3 Compound ≠ Compound! Compound 6 Compound 7 Compound? Compound R H3 Compound IQ Compound/1 Compound lλ Compound/3 Compound/≠ Compound/! Compound/B Compound/7 Compound/r Compound l? O Compound 2Q fH Compound λ1 Compound 22 CH2CC) 13 Compound Ko3 Compound λ≠ Compound Ko! The compound represented by the general formula (I) can be used as a commercially available product as it is or after being purified if necessary. Also known methods (for example, by The Chemist)
ry of Am1desJ, JACOB ZAB
Edited by ICKY, IntersciencesPubli
It is also possible to use it by synthesizing it according to [Published by Shers].

One or more compounds represented by the general formula (I) can be used in combination with gold. The mixing ratio (weight) of the diester dicarboxylic acid and the compound of general formula (I) is Tade, jlo, j
-Koj/7! Can be used in the range '? '
? It is particularly preferable to use it in the range of //-30/10. Is a conventionally known non-aqueous solvent suitable for the mixed solvent system of the present invention? Further, they can be used in combination. in this case,
The mixed solvent system of the present invention is preferably 30% to 99% by weight of the recording liquid, particularly preferably 10% to 1% by weight! 6, the desired results can be obtained.

Examples of non-aqueous solvents that can be used in combination with the compound of the present invention include ethanol, ktanol, heptatool, octatool, 7-chlorohexanol, benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, furfuryl alcohol, and anisyl alcohol. Alcohols from Alcohol Nato, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene gelicol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether,
Glycol derivatives such as ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate, benzyl methyl ketone, benzyl acetone, diacetone alcohol, cyclohexanone, etc.CD
'ltons, butyl phenyl ether, benzyl ethyl ether, hexyl ether sodium ethers, ethyl acetate, amyl acetate, benzyl acetate, phenylethyl acetate, phenoxyethyl acetate, ethyl phenylacetate, benzyl propionate, ethyl benzoate, Esters such as butyl benzoate, ethyl laurate, butyl laurate, isopropyl myristate, isopropyl tinate, triethyl phosphate, tributyl phosphate, petroleum ether, petroleum benzine, tetralin, decalin, t-amyl Examples include hydrocarbon solvents such as benzene and dimethylnaphthalene.

As the recording agent used in the present invention, many conventionally known hydrophobic dyes are effective. Tomatoe dyes include monoazo, polyazo, metal complex azo, pyrazolone azo, stilbene azo, various azo dyes such as thiazole azo, anthrone, anthraquinone dyes consisting of anthraquinone derivatives, indigoid dyes consisting of indigothioindigo derivatives, phthalocyanine dyes, diphenylmethane, and Examples include phenylmethane, xanthine, and acridine-based carbonium dyes, azine, oxazine, and thiazine-based quinone imine dyes, polymethine and azomethine-based methine dyes, benzoquinone and naphthoquinone dyes, naphthalimide dyes, and perinone dyes. Other special public services 1986-
It is also possible to use the hydrophobic dyes described in ≠Ko1r33 and JP-A-5R-3IRtta. These recording agents preferably contain 7 to 20% by weight of the recording liquid, and 3 to 20% by weight of the recording liquid.
It is particularly preferable to contain IO in an amount of % by weight.

Various additives may be added to the recording liquid of the present invention as desired. Examples of such additives include viscosity modifiers, surface tension modifiers, resistivity modifiers, film forming agents, ultraviolet absorbers, antioxidants, antifading agents, and the like.

The recording liquid of the present invention can be prepared by adding solvent components or various additives as appropriate to achieve desired physical property values.
Applicable to various inkjet recording devices.

When the recording liquid of the present invention is applied to an inkjet recording device using electrostatics, the specific resistance of the recording liquid tlO5 to 101
It is preferable to adjust to 1 Ω・σ, and 706 to 10
Ω・I is particularly preferred. Also, the viscosity of the recording liquid is /~30c
It is preferable to adjust pVC, and 3 to 50ocp is particularly preferable (zt'ctllJ determination).

The recording support used for recording with the recording liquid of the present invention is usually paper, but cloth, plastic film, metal plates, wood plates, glass plates, etc. can also be used. Paper is mainly made of wood pulp, but synthetic fibers, synthetic fibers, R-lube, inorganic fibers, etc. can be mixed as needed. In addition, a sheet provided with a suitable ink absorbing layer on the surface of the support allows the recording liquid to permeate to an appropriate degree, giving preferable results.

The ink absorbing layer is mainly composed of pigments and adhesives, and conventionally known materials can be used as appropriate. Examples of pigments include clay, talc, calcium carbonate, calcium sulfate, calcium silicate, zinc oxide, kaolin, aluminum silicate, magnesium silicate, acid clay, magnesium oxide, magnesium carbonate, aluminum oxide, silica, and organic pigments. It will be done. Examples of the adhesive include casein, starch, gelatin, PVA, carboxymethyl cellulose, hydroxyethyl cellulose, styrene butadiene latex, methyl methacrylate, butadiene latex, vinyl acetate latex, polyacrylic latex, and the like.

The present invention will be explained more specifically in the following examples.

Example/ After mixing and stirring the above components to make a uniform solution,
The ink solution was prepared by filtration through a μm filter. The specific resistance of this ink liquid is 3.7×io7Ω・α, and the viscosity is 4. rcp (both measured by CO!OC). This ink solution was placed in a flat-bottomed glass container and left open for 3 weeks (average room temperature 23cm).
°C) The weight loss rate of the ink liquid was o.t%, and no major changes in physical properties were observed. The nozzle hole diameter of this ink liquid! Using an electrostatic acceleration type inkjet device equipped with a 0 μm head, the dots were printed on inkjet recording paper at the number of dots/fi, and a clear, high-density magenta image was obtained. When the inkjet device was left with the head filled with this ink installed for three weeks and then restarted, the ink was ejected smoothly and an image with the same sharpness and high 11 degree angle as before the ink was stopped was obtained.

Paper printed with this ink was immersed in water for 10 minutes without any bleeding or running of the image. During printing with this ink, almost no odor was felt, and the odor of the printed paper was also very slight.

[Magenta dye]

C3H11' Example λ The following ink liquid of Composition Technique 9 and comparative type ink liquid were prepared in the same manner as in Example. The same oil-soluble magenta dye as in Example 1 was used.

Ink liquid Co 1 Ink liquid Co λ Ink liquid 2-3 Ink liquid Co ≠ Comparison type - / Comparison type Co For each of these ink liquids, those within 3 days after preparation (
Using the same electrostatic acceleration type inkjet device as in Example 1, we printed inkjet recording paper using the same electrostatic acceleration type inkjet device as in Example 1. After printing, the density of the printed image at this time is shown in Table 1 together with the physical property values of the ink liquid.

As can be seen from Table 1, the recording liquid used on the compound of the present invention showed little change in resistivity over time, and the image density value was stable. Furthermore, the recording liquid of the present invention gave clear images at 7 yap both immediately after preparation and after 3 months of use.

Claims (1)

[Scope of Claims] An inkjet recording ink mainly composed of a recording agent and a liquid medium, characterized in that it contains a dicarboxylic acid diester and a compound represented by the following general formula (I). General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, R_1 is an alkyl group, an aryl group, a heteryl group,
It represents an alkyloxy group, an aryloxy group, a heteryloxy group, an alkylamino group, an arylamino group, an arylalkylamino group, or a heterolylamino group. R_
2 and R_3 each represent a hydrogen atom, an alkyl group, an aryl group, or a heteryl group. However, R_2 and R_3 do not become hydrogen atoms at the same time. R_1 and R_2 or R_
2 and R_3 may be taken together to form a ring.