JPS58113272A - Water-based ink for ink jet recording - Google Patents

Abstract

PURPOSE:The titled ink that contains a water-soluble direct dye, a water- soluble acid dye, a polyhydric alcohol or its alkyl ether, diacetin and water, thus showing high jetting stability, preservability, and water resistance and giving images of high brightness and concentration. CONSTITUTION:The objective ink is composed of (A) a water-soluble direct dye and/or a water-soluble acid dye, preferably a polyazo dye of the formula (Q1, Q2 are unsubstituted benzene or naphthalene ring or benzen or naphthalene ring substituted with amino, hydroxyl or sulfone group; R1-R4 are H, sulfone; where sulfones are sodium, potassium or ammonium salts and 2-6 sulfones are included in one molecule), (B) a polyhydric alcohol or its alkyl ether, (C) diacetin and/or monoacetin and (D) water where the content of component A is 0.5- 8.0wt%, component B is 5.0-50.0wt% and component C is over 1.0wt%. EFFECT:Change in physical properties of the ink is little, even after it is used for a long time by circulation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved aqueous inkjet recording ink.

In inkjet recording, in order to perform good recording, various conditions are required for the ink used.

The physical properties of ink depending on the droplet generation method and droplet flight direction control method include ink viscosity, surface tension, specific conductivity,
It is necessary that the density is within an appropriate range. and,
Precipitation must not occur due to chemical changes during long-term storage, long-term use, or recording suspension, and the physical properties of the ink must not change. The ejection nozzle of a recording device generally has a diameter of about 10 to 60 μm, and if the nozzle is clogged due to precipitation, droplets cannot be ejected. Even if the nozzle is not completely clogged, if solid matter or sticky matter adheres to the vicinity of the nozzle, or if the physical properties of the ink that were adjusted to desired values during ink formulation change, recording performance, ejection stability, and ejection response may deteriorate. descend.

The recorded image has sufficiently high contrast,
It is desired that it be clear. In conventional inks, when attempting to increase the contrast of an image by increasing the dye content in the ink, there is a tendency for the 11-output nozzle to become clogged. Therefore, there is a need for dyes that have high solubility in the solvent used in ink and a high extinction coefficient.

It is also necessary to dry quickly after printing. Conventional ink contains a large amount of wetting agent to prevent nozzle clogging due to drying of the ink inside the nozzle during printing pauses. Special paper with high quality is used. As a result, not only does image smearing occur significantly, but it also becomes impossible to use many types of ordinary paper.

In addition, it is naturally required that recorded images have water resistance, light resistance, and abrasion resistance.

Until now, many proposals have been made as inkjet recording inks, but in reality, no ink has been obtained that satisfactorily satisfies all of the above conditions.

The present invention was made in view of the current situation, and it is an object of the present invention to provide an aqueous ink for inkjet recording that satisfies all of the above-mentioned conditions. In other words, the ink does not cause clogging of the ejection nozzle, deterioration or precipitation during storage, has good ejection stability and ejection response, and has small changes in ink physical properties even when used for long periods of time, and does not record well. The purpose of this invention is to provide an ink with excellent water resistance, less image bleeding, high density, and clearness.

That is, the present invention uses at least one of water-soluble direct dyes and water-soluble acid dyes, at least one of polyhydric alcohols and alkyl ethers of polyhydric alcohols, at least one of diacetin and monoacetin, and water. This is an aqueous inkjet recording ink characterized by containing:

The dyes that can be effectively used in the present invention are water-soluble direct dyes and water-soluble acid dyes such that the prepared ink can satisfy the above-mentioned properties. These dyes are used after being dissolved in a solvent that is appropriately selected as desired. The representative ones are listed below. Of course, these are representative, and other dyes having structures similar to these may also be used.

◇Water-soluble direct dyes c, r, direct black 1, 8, 11, 12, 2
4.

26.27, 33, 39, 44, 50.58, 85, 8
6,88.98.100,110,144 C,1,Female Electred 1,2,4,9,11,1
3, 17. 20, 23, 24, 28. :31,33,3
7, 39, 44, 62, 81.

83.99,227 C, t, Direct Blue 1.2, 6, 8, 15, 2
2,25, γ1,76, γg, 86.98,108,1
20,192,193゜194.195,196,19
9,200,201,202,203°207.236
, 237 C, 1, Direct Black 2, 4, 17, 19, 2
2.

32.38.51, 56, 62, 71.74, 75, 7
7.105.

108.112,154 ◇Water-soluble acid dye C,1, acid yellow 7.17,23,29,4
2,99C0[, acid orange 56.64C,1
, Acid Red 18.87, 92.94c, r, Acid Blue 1.7, 9, 234, 236C, t,
Acid Green 12,19,27,41C,1, Acid Black 1,2,7,24.94 Particularly preferred water-soluble dyes include the following general formulas (A), (8), (
There are polyazo dyes represented by C) and (0).

Here, Q+ and Q2 represent a benzene ring or naphthalene structure which is unsubstituted or substituted with an amino group, hydroxyl group or sulfone group, R1-R4 are a hydrogen atom or a sulfone group, and the sulfone group is a sodium salt or potassium salt. Alternatively, it takes the form of a quaternary ammonium salt and has 2 to 6 sulfone groups per molecule.

Here, Q s and Q s are unsubstituted or substituted phenyl groups or nanotyl groups, Q4 and Q5 are unsubstituted or substituted 1
．． 4-7 enylene group or notutin group, Rs, R
s is either a hydrogen atom, a water group, or an amine group, R7 and Ra are a hydrogen atom or a sulfone group, and the sulfone group is in the form of a sodium salt, potassium salt, or quaternary ammonium salt, and one molecule It has 2 to 6 sulfone groups per. X is -NH, -N-N-1-C)-1
=cH-.

n is O or 1.

t, -Q 7 and Q s are unsubstituted or substituted phenyl groups or naphthyl groups. OB is unsubstituted or substituted 1.
4-phenylene group, 1,4-naphthylene group or 4,
It is a 4-biphenylene group.

R9 and R8° are either a hydrogen atom, a hydroxyl group or an amino group. Ru\R12 is a hydrogen atom or
IL, a phone group, the sulfone group being in the form of a sodium salt or a potassium salt or a quaternary ammonium salt;
It has 2 to 6 sulfone groups per molecule.

R13RI4 Here, 01o and Q12 are substituted or substituted phenyl groups or naphthyl groups. Q u kJ unsubstituted or substituted 1.4
-phenylene group, 1,4-naphthylene group or 4.4
--Biphenylene group. .

R13 and R14 are either a hydrogen atom, a hydroxyl group or an amino group. R15, R+s is a hydrogen atom or a sulfone group, and the sulfone group is in the form of a sodium salt, a potassium salt, or a quaternary ammonium salt;
It has 2 to 6111 sulfonic groups per molecule.

Specific examples of the dye represented by the general formula (A) include the following.

(A-1) has the following.

o3Na Specific examples of the dye represented by the general formula (C) include the following.

Specific examples of the dye represented by general formula (D) include the following.

5o3Na 5O3Nn (D-
1) Examples of polyhydric alcohols that can be used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, and polyethylene glycol.

Examples of alkyl ethers of polyhydric alcohols include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monoethyl ether, and Tri-J.

Examples include ethylene glycol 7-methyl ether and triethylene glycol monoethyl ether.

Among these, a mixed solvent of at least one of polyhydric alcohols and alkyl ethers of polyhydric alcohols and glycerin is particularly preferred.

In the present invention, water is used as a solvent component, but water can also be used in combination with the following water-soluble organic solvents. For example, amines such as triethanolamine,
N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3
-Nitrogen-containing heterocyclic systems such as dimethylimidazolidinone, intramolecular ester systems of oxycarboxylic acids such as valerolactone and caprolactone, and cellosolve acetate systems such as ethylene glycol monomethyl ether acetate.

In the present invention, the content of the water-soluble direct dye and the water-soluble acid dye is in the range of 0.5 to 8.0% by weight in the entire ink,
The content of polyhydric alcohol and alkyl ether of polyhydric alcohol is 5.0 to 50.0% in mold mouth % in the total amount of ink.
It is preferable that the content (1) of diacetin and monoacetin is 1.0% or more in terms of % of heavy water during the entire heat of the ink.

In the present invention, any commonly known substance can be used as a viscosity modifier, provided it is effective without adversely affecting the solvent and dye used. Examples include polyvinyl alcohol, hydroxyl methylcellulose, carboxymethylcellulose, methylcellulose, water-soluble acrylic resin, gum arabic, dextrin, casein, pectin, gum tragacanth, polyvinylpyrrolidone, and the like.

As a pH adjusting agent that can be suitably used in the present invention, it is possible to adjust the pH of the ink without adversely affecting the ink.
Any material can be used as long as it can control the value within the range of 9.0 to 11.0.

For example, it is formed by amines such as jetanolamine and triethanolamine, hydroxides of alkali metal elements such as sodium hydroxide and potassium hydroxide, strong bases such as ammonium hydroxide, sodium carbonate, and potassium carbonate, and weak acids. There are water-soluble salts, etc.

Other substances that can be added to the ink include the following:

The specific electrical conductivity of the ink is Ill v/Cm (25
Examples of specific electrical conductivity modifiers to achieve a specific electrical conductivity of 100% or higher include, for example, inorganic salts such as potassium chloride, ammonium chloride, sodium sulfate, and sodium carbonate, water-soluble amines such as triethanolamine, and tetramethylammonium bromide. There are quaternary ammonium salts, etc.

Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate.

Examples of rust preventives include acidic sulfites, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate,
Examples include dicyclohexylammonium nitrite.

Water-soluble antiseptic mold agents include 2,2-dimethyl-6-acetoxy-dioxane-1.3, sodium dehydroacetate,
Examples include p-hydroxybenzoic acid butyl ester, potassium sorbate, sodium 2-pyridinethiol-1-J oxide, and anionic surfactants. This kind of product is commercially available with the product name Bi A → J ID 880 (
(made of table surface).

In addition, depending on the purpose, water-soluble ultraviolet absorbers, water-soluble infrared absorbers, magnetic fluids consisting of ultrafine magnetite particle dispersion systems, surface oxidized carbon black with improved water dispersibility, hydrophilic oligomers, polymers, substituents It is possible to add carbon black or the like to which is added.

It is necessary to adjust the surface tension of the ink of the present invention, which is made by appropriately mixing the above-mentioned materials, to a value of 406 yne/cm (25°C) or less in order to suppress image blurring and ensure ejection stability. It is.

Examples are shown below. All percentages are ψ luster percentages.

Example 1 C, 1, Direct Black 19 3.25% Glycerin 3.75% Diethylene Glycol 11.25% Diacetin
3.00% Sodium 2-pyridinethiol-1-oxide
0.30% ion exchange water 78.
A mixture consisting of 45% was heated to 10° C., stirred and dissolved, and then filtered twice through a membrane filter with a pore size of 0.22 μm to obtain an ink.

The physical properties of the obtained ink are surface tension 7-58. Odyne/cm (25
°C) Viscosity η= 1.7 c, p, (3
0℃) 1) HpH-10.5 (25℃) Specific electrical conductivity -2.5ll1y/am < 25
℃) Next, the following test was conducted using this ink.

1) Image clarity and image drying property: When ink was jet-recorded on commercially available high-quality paper using a nozzle with an inner diameter of 30 μm at a particle formation frequency of 100 KH2, a clear image was obtained. The drying time of the recorded matter was within 10 seconds at room temperature and humidity.

2) Storage: Seal the ink in a glass container and store at -20°C for 1 month, 4
1 month at ℃, 1 year at 20℃, and 1 week at 90℃.
Although both were stored, no precipitation was observed. Further, no change was observed in the physical properties or color tone of the ink.

3) Jetting stability: The jet recording described in 1) above was performed continuously for 1000 hours, and stable recording was achieved without any clogging of the nozzle or change in the jetting direction.

4) Jetting response: After jet recording was performed according to 1) above, the jet was left at room temperature and humidity for one month and at 40°C and 30% RH for one week, and then jet recording was performed again according to 1). As in 3) above, stable recording was possible.

An ink having the following formulation was prepared in the same manner as in Example 1.

Example 2 Trisazo dye C-13 described in the text, 25% diethylene glycol 13.30% noacetin 6.10% preservative and fungicide (trade name Biocide 880 [manufactured by Taihan]) 0.30% ion-exchanged water 76. The physical properties of the ink obtained by 45% are γ=60. Odyne/cs (25℃) η-1,
8c,p, (30℃) EI H-10,5 (25℃) = 2.8 m″'u″/cm (25℃)
Example 3 C,1, Acid Red 92 3.00% polyethylene glycol 200 12,00% diacetin 0.30% tri-1-tanolamine 0.20% sodium dehydroacetate 0.20% ion exchange water
78.60% Ink physical properties are 7=59.0 dyne/cm (25°C) η=
1.7 c, p, (30℃) pH-9,9 (
25℃) tr, = 3.1 mU/am (25
℃) Comparative Example 1 C, 1, Direct Black 19 3.25% Glycerin 6.15% Diethylene Glycol 11.25% Sodium 2-Pyridinethiol-1-oxide 0.30% Ion Exchange Water 78.45% Ink physical properties are 7 =61. Odyne/cm (25℃) η-1,
7c, p, (30℃) 1) H = 10.5 (25℃) = 2.5
1! lV/CIR (25°C) Comparative Example 2 Trisazo dye IlI C-13,2 described in the text! ]% Diethylene glycol 13.00% Antiseptic agent (trade name Biocide 880 [made by base surface]) 0.30%
Ion exchange water 76.45% Ink physical properties are 7=60. Odyne/cm (25℃) η-1,
80c, p, (30°C) 1) H-10,5 (25°C) to -2,8gi U”/CI (25°C) Comparative Example 3 C,1, Acid Red 92 3.00% Polyethylene Glycol 200 18 ,00% Tori J
Tanolamine 0.20% Sodium dehydroacetate 0.30% Ion exchange water
78.60% Iraq physical properties are 7-60. Odyne/am (25℃)77-1
．． 70 0. D, (30°C) 1) H-9,9(
-3.1 mV/am (25°C) Next, the inks of Examples 2 and 3 were tested for the same jetting response as Example 1, and the same good results as Example 1 were obtained. was gotten. On the other hand, in the case of Comparative Examples 1 to 3, 1 at room temperature and normal humidity.
After one day of storage at 40° C. and 30% RH, the nozzle became partially clogged, the direction of ink jetting became extremely unstable, and jet recording was impossible.

Patent applicant: Ricoh Co., Ltd. Agent Patent Attorney Hidetake Komatsu

Claims (1)

[Claims] 18, at least one of water-soluble direct dyes and water-soluble acid dyes, at least one of polyhydric alcohols and alkyl ethers of polyhydric alcohols, at least one of diacetin and monoacetin, and water. Characteristic water-based ink for inkjet recording.