JPS6369875A - Ink for ink-jet recording - Google Patents

Abstract

PURPOSE:To improve ejection stability and recording characteristics of an ink composed mainly of a recording agent and a liquid medium, by adding a phthalic acid ester and a specific compound to the above ink. CONSTITUTION:An ink-jet recording ink composed mainly of a recording agent and a liquid medium is incorporated with a phthalic acid ester (preferably diethyl phthalate) and a compound of formula I [R is 4-9C (substituted) alkylene; R1 and R2 are (substituted) alkyl; sum of C numbers of R, R1 and R2 is 9-16] (e.g. the compound of formula II). The weight ratio of the phthalic acid ester to the compound of formula I is preferably 10/90-70/30.

Description

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

``Prior Art'' Inkjet recording methods include a single-pressure vibration type-pressure coupler type, an electrostatic acceleration type, and the like, depending on the method of generating recording liquid droplets. In all of these methods, a desired recorded image is obtained by ejecting ink droplets from fine ink ejection orifices while controlling the droplet size, ejection direction, etc.

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 a single droplet will not be possible, and in some cases, nozzles may become clogged, resulting in one recorded image. image quality is significantly impaired. Currently, water-based inks that use water and water-miscible organic solvents as liquid media are mainly used as inkjet recording inks. However, because the liquid medium evaporates relatively slowly, clogging of the nozzle is likely to occur. This is a drawback. In order to solve this problem, various efforts have been made in terms of ink composition and equipment, but they have not yet reached the point of completely solving the problem. It is known that one method of completely solving the problem of 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 as the ink liquid medium.

For example, Japanese Patent Publication No. 1973-J41. No. J7r proposes that a recording liquid with no nozzle clogging and excellent recording stability can be provided by using conolic acid esters in the liquid medium of inkjet recording ink. Diethyl succinate used in the examples of the patent has a boiling point of 2.
Since the temperature is relatively high at 17°C and the evaporation rate is slower than that of mono-aqueous inks, it can be expected that nozzle clogging will occur less easily.

However, diethyl succinate has an aromatic odor, which is particularly strong when printed on a recording sheet. Considering the case of printing a large number of sheets over a long period of time, the odor of diethyl phosphate is not practical. The benzoic acid esters proposed in Japanese Patent Application Laid-Open No. 2006-200026 are also found to have the disadvantage of odor. Tokukai Akira! No. 7-3j7 proposes an alkylnaphthalene compound as a liquid medium that is uninteresting and has low toxicity.

However, since this compound is a nonpolar solvent, when used as an ink liquid, the specific resistance value becomes significantly high. In order to adjust the specific resistance value to an appropriate value, if a polar solvent such as a specific resistance regulator such as benzyl alcohol is used in a large amount, the specific resistance value of the ink liquid tends to change over time and the stability of one liquid deteriorates.

Phthalate esters used in JP-A-9-10933, JP-A-J9-6-671-JP-A-J9-7/372, etc. are stable solvents with a high boiling point and do not have a bitter odor. It is known to have very little toxicity to the human body.

However, as a liquid medium, inkjet recording inks that use phthalate esters alone tend to have high specific resistance and viscosity values - for this reason, the amount of ejection during printing is small and the density of a recorded image is insufficient. . It is sufficient to mix and use a liquid medium that can lower the specific resistance value and viscosity value without reducing the dissolving ability of the dye.

Selecting a low toxicity, odorless solvent poses considerable difficulties.

``Problems to be solved by the invention'' In this way, while maintaining high dye solubility, liquid physical properties such as viscosity and specific resistance - safety for the human body.

It has been extremely difficult to find a recording medium liquid that satisfies all aspects such as odor and liquid composition stability.

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.Another purpose of the present invention is to provide an inkjet recording ink (hereinafter referred to as "recording liquid") that is safe for the human body. To provide a recording liquid with low odor. Another object is to provide a recording liquid which gives sharp and contrasting images - still another object.
An object of the present invention is to provide a recording liquid that provides images with excellent water resistance.

"Means for Solving Problems" The purpose of this is to create an inkjet recording ink mainly composed of a recording agent and a liquid medium, which contains a phthalate ester and a compound represented by the following general formula rI). This can be achieved by using an inkjet recording ink having all these characteristics.

-Yo- General formula (Il R10-C-R-COR2 In the formula above, an alkylene group substituted with an alkylene group or an alkoxy group having a number of carbon atoms is represented.

R1 and R2 represent an alkyl group, which may be substituted with an alkoxy, carbamoyl, or ester-acylamino group. However, the total number of carbon atoms of R-R1 and R2 is in the range of ~/.

The recording liquid of the present invention consists of a liquid medium as a carrier for the recording agent, a recording agent for forming a recorded image, and additives added as necessary to obtain desired characteristics. It is essential to use the compound of general formula (I) in combination. The compound represented by the general formula (1) 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 is also less toxic to humans and has almost no odor. It has been found that when the compound represented by the general formula (I) is used in combination with a phthalate ester, the solubility of the dye is synergistically improved. Since it is possible to increase the amount of dye contained in the recording liquid, it is possible to obtain sharper and higher contrast images.

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

Since the recording liquid of the present invention has a significantly lower evaporation rate than water, the liquid composition does not change much even when left unsealed in the air and has excellent liquid stability.

Therefore, 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. Furthermore, the recording liquid of the present invention is
It has low odor, low flammability and low toxicity, and has desirable properties as an inkjet recording liquid. Furthermore, images drawn with the recording liquid of the present invention are excellent in -1 water resistance without causing any bleeding or staining due to water.

The phthalate esters used in the present invention include dimethyl phthalate, diethyl phthalate, di(Jl)propyl phthalate, diisopropyl phthalate, dibutyl phthalate-diisobutyl phthalate, and especially diethyl phthalate. I like it.

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

Compound 1 O H7O3(n) 0-C-(CH214-CO(n)C
3H7 compound II IIH7C3 (is
o> -0-C-(CH2)4-C-0-(iso)
C3H7 compound 3 lll HgC4(n) 0-C-JCH2)4 CO(n)
C4H7H3O-0-(CI(2)2-0-C-(CH
2) 4-C-0-(CH2)2-0-CH3H9O, (
n)-0-fcI(2)2-0-C-f 0(2)4
-c-o-(CH2>2-O-(n)C4H9H2O
2-0-C-JCH215-C-0-C2H5H2O2
-0-C-(CH2)5-C-0(n)c4HgII
II H2O2-0-C-JCH2)6-C-0-C2H5 crystal 3 -ter compound IO H3O-0-C-rcH2h -C-0-CH3 compound l1 H2O2-0-C-JCH2)7-C-0 -C2Hs compound l coH2O2-0-C-JCH2>8-C-0-C2H5H
g C4(n)-0-C-(CH2)B-C-0-(
n) C4H9H3C-0-C-(Cl12)9-c-o
-c 2H5 compound/! H2O2-0-C-(CH2+9-c-Q-c 2H5
IO- The compound represented by the general formula (I) is a commercially available product.
Alternatively, it can be purified and used if necessary.

Alternatively, it may be synthesized and used by a known method (for example, Dai Organic Chemistry, Vol.

The compounds represented by the general formula (I) used together with the phthalate ester can be used in combination of one or more kinds. The mixing ratio (weight) of the phthalate ester and the compound of general formula rI) is j/93-9! It can be used in the range of /j, but it is particularly preferably used in the range of +10/90 to 70/3θ. A conventionally known non-aqueous solvent may be further mixed with the mixed solvent system of the present invention.

in this case.

The desired results can be obtained by containing the mixed solvent system of the present invention in an amount of 30 to 50% by weight, particularly preferably 7 to 70% by weight per recording liquid. Examples of non-aqueous solvents that can be used in combination include ethanol, hantanol, heptano-octano-cyclohexanol, benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, alcohols such as furfuryl alcohol and anise alcohol, and ethylene. Glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether-diethylene glycol monobutyl ether.

Propylene glycol monoethyl ether - propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate - ethylene glycol diacetate - propylene glycol diacetate Glycol derivatives such as benzyl methyl ketone, benzyl acetone, diacetone alcohol, cyclohexanone and other ketones - Ethers such as butylphenyl ether, benzyl ethyl ether and hexyl ether - Ethyl acetate - Amyl acetate.

Benzyl acetate, phenylethyl acetate, phenoxyethyl acetate-phenyl ethyl acetate, benzyl propionate, ethyl benzoate-butyl benzoate-ethyl laurate, butyl laurate-isopropyl myristate-/e-impropyl lumitate, triethyl phosphate, phosphoric acid Tributyl, diethyl malonate-dipropyl malonate, diethyl diethyl malonate, diethyl succinate, dibutyl succinate.

Diethyl adipate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate,
Esters such as dioctyl fumarate, petroleum ether,
Petroleum benzene, tetralin.

Hydrocarbon solvents such as decalin, t-amylbenzene, dimethylnaphthalene, acetonitrile-formamide-
Examples include polar solvents such as N-N-dimethylformamide-dimethylsulfoxide, sulfolane, propylene carbonate, and N-methyl-pyrrolidone-N-vinylcopyrrolidone.

Alcohols have relatively low resistance when used in inkjet recording devices that use electrostatics.

-l 3- Add glycol derivatives, ketones, and polar solvents to the recording liquid.
A content of 30% gives favorable results.

As the recording agent used in the present invention, many hydrophobic dyes known in the art are effective. For example, various azo dyes such as monoazo-polyazo, metal complex azo-pyrazolone azo, stilbene azo, and thiazole azo, anthraquinone dyes made of anthrone-anthraquinone derivatives, indigoid dyes made of indigo-thioindigo derivatives, phthalocyanine dyes, diphenylmethane, triphenylmethane dyes, etc. Xanthine, acridine-based carbonium dyes, azine, oxazine-thiazine-based quinone imine dyes, polymethine-azomethine-based methine dyes.
Examples include benzoquinone and naphthoquinone dyes, naphthalimide dyes, and perinone dyes. Other Special Public Sho JO
-! KoIr33, JP-A-Sho J-j-3! Hydrophobic dyes described in No./j1 can also be used. These recording agents preferably contain /~-20% by weight of the recording liquid,
It is particularly preferable to contain 3 to /θ weight ratio.

-/≠- One type of additive may be appropriately 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 one solvent component or various additives as appropriate and adjusting it to desired physical property values.
Applicable to various inkjet recording devices.

When the recording liquid of the present invention is applied to an inkjet recording apparatus using total electrostatic charge, the specific resistance of one recording liquid is 705 to 705. ．． 1
It is preferable to adjust it to 1Ω/sub.

It is particularly preferable to adjust the viscosity of the recording liquid from 1 to 30 cpVc, and from 3 to 30 cpVc.
20 cp is particularly preferred (,2J-.C measurement).

The recording support used for recording with the recording liquid of the present invention is usually one piece of paper, but cloth, plastic film, metal plate, wood plate, glass plate, etc. can also be used. The paper is mainly made of wood pulp, but if necessary, synthetic fibers, synthetic parboiled inorganic fibers, etc. may be mixed therein. A sheet with a suitable ink absorbing layer on the surface of a rolled support is
The entire recording liquid permeates to a suitable extent, giving favorable results.

The ink absorbing layer is mainly composed of a pigment and an adhesive, and any conventionally known ink absorbing layer can be used as appropriate. Examples of pigments include clay, talc 5 calcium carbonate-calcium sulfate, calcium silicate, zinc oxide, kaolin-aluminum silicate, magnesium silicate, acid clay-magnesium oxide, magnesium carbonate, aluminum oxide, silica, organic pigments, etc. It will be done. Examples of the adhesive include casein, starch, gelatin-PVA-carboxymethylcellulose-hydroxyethylcellulose, 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 1 1 Oil-soluble magenta dye [shown below] j parts by weight The above components were mixed and stirred to form a uniform solution, and then filtered through a filter with a pore size of 1 μm to prepare an ink liquid. The specific resistance of this ink liquid is 3. j×10 7 Ω·ffi, and the viscosity was 7#cp (both measured at 2!0C). This ink liquid 1. ! t'5r: diameter μ.

When the ink liquid was placed in a flat-bottomed glass container and left open for 3 weeks (average room temperature: 3°C), the weight loss rate of the ink liquid was /J4. Also, large changes in physical properties were observed. There wasn't. The nozzle hole diameter of this ink liquid! The number of dots/1 mK was printed on inkjet recording paper using an electrostatic acceleration type inkjet device equipped with a 0 μm head.

A clear, high-density magenta image was obtained. When the inkjet device was left in place for three weeks with the head filled with this ink liquid attached, and then restarted, the ink liquid discharged smoothly and an image with the same clarity and high density as before the printing was stopped was obtained. Even when paper printed with this iron ink was immersed in water for 10 minutes, no bleeding or running of the image was observed. During printing with this ink, almost no odor was felt, and the odor of the printed paper was also very slight.

[Magenta dye]

Example λ An ink liquid having the following composition and a comparative type ink liquid were prepared in the same manner as in Example 1. The same oil-soluble maze/interdye as used in Example 7 was used.

Ink liquid Co / Ink liquid - 1 Coin Ink liquid 2-3 Ink liquid Co μ Comparative type - / Comparative type Co The viscosity and specific resistance values (measured at 2j0C) of each of these ink liquids are shown in Table 1.

Each of these ink liquids was printed on inkjet recording paper using the same electrostatic acceleration type inkjet device as in Example 1. Table 1 shows the ejection properties, the density of the printed image, and the odor of the printed paper at this time.

Also each ink liquid/,! f/ was placed in the same flat-bottomed glass container as in Example-/, and the results of observing the state of dye precipitation after standing for 3 weeks are also shown at the same time.

-,2/- As can be seen from Table 7, the recording liquid using the diethyl phthalate of the present invention and the compound represented by the general formula (I) has the following properties: Satisfactory results were obtained in terms of dye precipitation.

Patent Applicant: Fuji Photo Film Co., Ltd. - 1966/1) Monthly 7th Patent "Government-1"
Incident display Showa J/Year Special Application No. 2/Jλ! No. 2, Title of invention Inkjet recording ink 3
, Relationship with the case of the person making the amendment Patent applicant Location 210-4 Nakanuma, Minamiashigara City, Kanagawa Prefecture Subject of amendment Column 5 of "Detailed description of the invention" in the specification The description in the "Explanation" section has been amended as follows.

/) "H7C3risol -0-C-fcH214-C-" of compound λ on page 10 line
0-11so) c3H7J O "H7C311so)-0-C-I CH2'14-C
-0-(1so)c3H7J.

, 2) 1st≠page/J'th line "Perinon" "Perinon" and correct it.

Claims (1)

[Scope of Claims] An inkjet recording ink mainly composed of a recording agent and a liquid medium, comprising a phthalate ester and the following general formula (
An inkjet recording ink characterized by containing a compound represented by I). General Formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ In the formula, R represents a substituted or unsubstituted alkylene group having 4 to 9 carbon atoms, and R_1 and R_2 represent substituted or unsubstituted alkyl groups. However, the total number of carbon atoms in R, R_1 and R_2 is in the range of 9 to 16.