JPS5975966A - Water-base ink for ink jet printing - Google Patents

Abstract

PURPOSE:To prevent nozzles from clogging in prolonged intermittent application and improve clarity and resistance of images to water and light, by using a particular azo dye as dyes in water-base inks for ink jet printings. CONSTITUTION:One or more of azo dyes of formula I (wherein Ar is phenyl, etc.; R1 is a hydroxyl group, etc.; R2 is amino, etc.; R3 is H, 1-4C alkyl, etc.; R4 is 2-6C hydroxyalkyl, etc.; R5 is H, alkyl, etc.; X is H, Na, etc.; Y is O, S, etc.; n is 0-1; m is 1-2) are incorporated to yield the intended water-base ink for ink jet printings. The compd. of formula II shown as an example of azo dyes of formula I is yielded by coupling a diazo compd. of p-nitroaniline with H acid in the acid range to yield a monoazo compd., and reacting with 2,4-diaminophenyl hydroxyethyl ether and c-acetoaminoaniline in turn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-based ink used in inkjet printing, and more specifically, the present invention relates to water-based ink used in inkjet printing, and more specifically, it has excellent water resistance, light resistance, and clarity without causing nozzle clogging even when used intermittently for long periods of time. This invention relates to a water-based ink for inkjet printing that forms images with excellent image quality.

Normally, water-based ink for inkjet printing is basically composed of a dye, a polyhydric alcohol or its ether called a wetting agent, and water, and the ink can be used to perform good inkjet printing. In order to do so, it is necessary to satisfy all of the following conditions.

That is, 1) The physical properties of the ink, such as viscosity, surface tension, specific conductivity, and density, are within appropriate ranges depending on the droplet generation method and droplet flying direction control method, and 2) Long-term storage and long-term use. Alternatively, low-solubility substances should not precipitate or solid substances should be precipitated due to chemical changes or the like during printing stops, and solid substances should not be attached near the nozzle where they are deposited. Furthermore, the physical properties of the ink, which were adjusted to desired values during ink formulation, do not change; 3) The printed image has sufficiently high contrast and clarity; 4) The printed image has water resistance and light resistance. , excellent abrasion resistance, and 5) quick drying after printing. However, a material that satisfies all of these conditions has not yet been obtained.

For example, in conventional black water-based ink, dyes such as C, 1, which has good water resistance and light resistance, Direct Black 2, 4,
17, 19, 22, 32, 38, 51, 56, 62, 7
1.

74.75, 77.105, 108.112, 154, etc. are used, and among these, C,1, Direct Black 19, 38.154 is particularly widely used in practical use.

However, since these conventional dyes have poor solubility, it is not possible to sufficiently increase the image density by increasing the m1 degree content. Further, even if the content of the ink is kept to a small amount, the dye coagulates and precipitates during storage or use of the ink, causing nozzle clogging, which greatly impairs jetting stability, jetting response, etc.

In order to improve these drawbacks, methods have been implemented in which dimethylformamide, pyrrolidone, ternolamine, and surfactants are added to the ink as dye solubilizers, or a large amount of a wetting agent is added. However, the use of these additives causes the following problems. For example, amines corrode various parts that make up an inkjet printing device. Further, it is preferable not to use a surfactant since it generates bubbles. Furthermore, the use of a large amount of wetting agent impairs the drying properties of the printed image, so special paper with high ink absorbency must be used. Therefore,
In order to solve the drawbacks caused by the use of additives as mentioned above,
There is a strong demand for dyes that have excellent solubility and can form images with excellent water resistance, light resistance, and abrasion resistance.

The purpose of the present invention is to provide a water-based ink for inkjet printing which solves the conventional drawbacks, and more specifically, it is an object of the present invention to provide a water-based ink for inkjet printing that solves the conventional drawbacks. By using one type of dye as a dye, the solubility of the dye is improved without impairing various properties such as water resistance and light resistance, thereby providing an aqueous ink that satisfies all of the above-mentioned requirements 5--characteristics.

That is, the gist of the present invention is a water-based ink for inkjet printing, which is characterized by containing at least one azo dye represented by the following general formula.

Ar: unsubstituted or substituted phenyl group, or unsubstituted or substituted naphthyl group.

R1: hydroxyl group or amino group.

R2: When RI is a hydroxyl group, it is an amino group; when R1 is an amino group, it is a hydroxyl group.

R3: hydrogen, halogen, or C1-4 alkyl group,
Alkoxy group or hydroxyalkyl ether group.

R4: C2-6 hydroxyalkyl group or C-61, or C? ~6 dihydroxyalkyl groups or ethers thereof.

R5: hydrogen, alkyl group, 02-6 hydroxyargyl group or ether thereof, or C? ~6 dihydroxyalkyl groups or ethers thereof.

X: hydrogen, Na, KSLi, or a cation such as an organic amine.

Y: oxygen, sulfur 1. Or nitrogen.

n: An integer from O to 1, provided that when Yl)<oxygen or sulfur, 0; when Y is nitrogen, 1°l: 1 or 2° Specific examples of the above dyes are shown below.

7- Na03S SO3Na
NHC2H40HNa03S SO3Na
NHC2H40H-9 9-l O- The method for producing the dye for aqueous ink of the present invention will be explained using the dye of Dye Example 1. A monoazo compound is obtained by acidically coupling a paranitroaniline diazotide to H acid. Then, the nitro group of this monoazo compound is reduced with Na2S to form an amine group, and then diazotized with sodium nitrite in the presence of hydrochloric acid at 0 to 10 DEG C. A coupler, 2,4-diaminophenol hydroxyethyl ether, is added to this diazotized solution, and a disazo compound is obtained by carrying out a coupling reaction while maintaining the pH value at 5 to 6 with an aqueous sodium acetate solution. Next, a diazotide of p-acetaminoaniline was added to this disazo compound under alkalinity with sodium carbonate for coupling, and then 80
The temperature was raised to 0.degree. C. and the acetyl group was hydrolyzed for 1 hour to obtain Dye Example 1).

The coupler 2,4-diaminophenol hydroxyethyl ether used in the above manufacturing method example is 2,4-dini! ~2.4 by reacting potassium salt of lophenol and ethylene bromohydrin in dimethylformamide at 130°C for 5 hours.
- obtain dinitrophenol hydroxyethyl ether,
Obtained by amination by catalytic reduction.

Further, hydroxyalkylated products of triaminobenzene, which are found in other dye examples, can be easily obtained by dissolving 2,4-dinitrochlorobenzene in dimethylformamide and gradually adding hydroxyalkylamine at 80°C.

In the ink of the present invention, the dye is usually contained in 0.5 to 5 parts by weight per 100 parts by weight of the ink.

If it is less than 0.5 part by weight, it lacks ability as a coloring agent, and 5
If the weight exceeds the weight part and a long period of time passes, precipitation will occur and good jet printing will not be possible.

Further, if necessary, a black dye of the present invention can be used in combination with the dye of the present invention. Dyes that can be used in combination include, for example, C, 1, Direct Black 2, 4, 17.1'
l, 22, 32.3B, 51.56, 62. Gate, 74.
75, 77.105, 108, 112, 154, C,
T, acid black 1,24.26.48,52.
5g, 60,107,109,119゜131, 1
These are direct dyes such as 55 and acid dyes.

Wetting agents used in the present invention include polyhydric alcohols and their ethers, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, polyethylene glycol, ethylene glycol monoethyl ether, and ethylene glycol. Glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, thiogetanol, etc., and 5 parts per 100 parts by weight of ink.
~30 parts by weight can be used, and two or more types may be used in combination.

In addition, sodium dehydroacetate, sodium 2,2-dimethyl-6-acedoxydioxane-1,3-benzoate, sodium thiois, ammono-thioglycolate, etc. may be added to the ink of the present invention as a fungicide. I can do it.

Examples of the present invention and comparative examples will be shown below.

14- Example 1 Dye Example 1 3.0 wt% glycerin 5. OWj% diethylene glycol 13. Owt% dehydroacetic acid (helium 0.2wt% ion exchange water)
78.8 wt% (i8 mixture was heated to 50° C., stirred and dissolved, and then filtered through a Teflon filter with a pore size of 0 and 22 μm to prepare an ink.

The obtained ink f1 has pH = 10.2 (25'C) viscosity -2.04
0,p, (25°C) Surface tension -50,5 dyne/am (25°C)
Met.

Next, we conducted the following test using this ink, and found that
The following satisfactory results were obtained.

1) Image clarity-3 and drying properties of both images: When the ink was jet-recorded on commercially available high-quality paper using a nozzle with an inner diameter of 30 μm and a particulation frequency of 100 KH7, 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.
It was stored at 4°C for 1 month, at 20°C for 1 year, and at 90°C for 1 week, but 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) Jet q4 response; After performing jet recording according to 1) above, it 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). However, as in 3) above, stable recording was possible.

Inks having the compositions of Examples 2 to 9 and Comparative Examples 1 to 4 were prepared in the same manner as in Example 1.

Example 2 Dye Example 3 3.5wt% glycerin 5. Owt% diethylene glycol 13. Owt% Sodium Dehydroacetate
0.2Wt% ion exchange water 78
．． The physical properties of the ink obtained by 3 wt% are: 1) I-1 = 10.4 (25°C) viscosity -2.02
0,p, (25°C) surface tension -49,8dyne
/cm (25°C).

Example 3 Dye Example 5 4.0 wt% glycerin 5. Owt% dielene glycol 13. Owt% Sodium dehydroacetate 0.2Wt% Ion exchange water
The physical properties of the ink obtained at 77.8 wt% are = 17-of-1-10,1 (25°C) Viscosity-2,08Q,p, (25°C) Surface distortion] =
It was 50.8 6 yne/cm (25°C).

Example 4 Dye Example 9 3.0 wt% polyethylene glycol 200 15.0 wt% triethylene glycol monomedyl ether 3.0 wt% p-ethoxybenzoic acid 0.2 wt% ion exchange water 78.8 wt% The physical properties of the obtained ink were pH=9.8 (25°C), viscosity -2,110.0, (25°C), and surface tension -49.2 dyne/cm (25°C).

Example 5 Dyeing O' difference 1 Example 11 3.5wt% polyethylene glycol 200 15.0wt% triethylene glycol monomedyl ether 18-3, Owt% p-ethoxybenzoic acid 0.2wt% ion-exchanged water The physical properties of the ink obtained at 78.3 wt% are: p) (=10.2 <25°C) Viscosity = 2.00 c, p, (25°C) Surface tension -50,4) dyne/am (25°C) Met.

Example 6 Dye Example 13 4.0wt% polyethylene glycol 200 15. Owt% triethylene glycol monomethyl ether 3, Owt% p-ethoxybenzoic acid Q, 2wt% ion-exchanged water 77.8 wt% The physical properties of the obtained ink are DH=10.3 (25℃) Viscosity -2.05c, p, (25℃) surface tension -49
, 5 dyne/cm (25°C).

Example 7 Dye Example 14 3.5wt% triethylene glycol monomethyl ether 20, Owt% 6-acetoxy-2,4-dimethyl-dioxane 0
, IWt % Sodium ethylenediaminetetraacetate 0.1 wt% Ion-exchanged water 76.3 wt% The physical properties of the obtained ink are: pH = 10.2 (25°C) Viscosity = 2.16 c, p, (25°C) Surface tension =
It was 48.8 dyne/cm (25°C).

Example 8 Dye Example 16 4.0wt% triethylene glycol monomethyl ether 20, Owt% 6-acetoxy-2,4-dimethyl-m-dioxane o
, iwt% Sodium ethylenediaminetetraacetate 0.1wt% Ion-exchanged water 75.8 wt% The physical properties of the obtained ink are +1H=10.4 (25℃) Viscosity=1.98 c, p, (25℃) Surface tension =50.7 dyne/am (25°C).

Example 9 Dye Example 18 4.0 wt% polyethylene glycol 200 15. Owt% Thiogetanol 5. Owt% sodium dehydroacetate 0.2 wt% ion exchange water
The physical properties of the ink obtained at 75.8 wt% are p 1-1 = 9.5 (25°C) viscosity = 2,2
5 c, p, (25℃) surface tension = 48.6 d
yne/cm (25°C).

Comparative Example 1 21- Dye (C, 1, Direct Black 19) 3.0
wt% glycerin 5. Owt% diethylene glycol 13. Owt% Sodium dehydroacetate 0.2wt% Ion exchange water
The physical properties of the ink obtained at 78.8 wt% were: +1H = 10.5 (25°C), viscosity = 2.45 a, o, (25°C) surface tension = 48.6 dyne/cm (25°C) .

Comparative Example 2 Dye (C, 1, Direct Black 38) 3.5
wt% glycerin s, o wt% diethylene glycol 13. Owt% Sodium dehydroacetate 0.2wt% Ion exchange water
The physical properties of the ink obtained at 78.3 wt% are T)) l=10.5 (25°C) 22- Viscosity -2,200, I), (25°C) Surface tension -4
It was 9.3 dVl/C11l (25°C).

Comparative Example 3 Dye Fl (C, 1, Direct Black 154) 3, O
wt% polyethylene glycol 200 15. Owt% triethylene glycol methyl ether 3 wt% p-ethoxybenzoic acid 0.2 wt% ion-exchanged water 78.8 wt% The physical properties of the obtained ink were as follows: pH=10.5 (25°C) Viscosity -2, 45c, p, (25°C) Surface tension -48,5 dyne/am (25°C).

Comparative Example 4 Dye (C, I, Acid Black 2) 3.5 w
t% polyethylene glycol 200 15. Owt% triethylene glycol monomethyl ether 3, Owt% p-ethoxybenzoic acid 0.2 wt% ion-exchanged water 78.3 wt% The physical properties of the obtained ink were as follows: pH=10. O (25℃) Viscosity -2, 20c, p, (25℃) Surface tension = 5
It was 0.5 dyne/cm (25°C).

When the inks of Examples 2 to 9 were tested for ejection response in the same manner as in Example 1, good results similar to those in Example 1 were obtained. On the other hand, in the case of Comparative Examples 1 to 4, the nozzle became partially clogged after being left for one cycle at room temperature and humidity, and for three days at 40°C and 30% RH, resulting in extremely unstable ink jetting direction. Therefore, jet printing was impossible.

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

Claims (1)

[Claims] The water f1 ink for inkjet printing is characterized in that it contains at least one azo dye represented by the following general formula.
Water-based ink for inkjet printing. r: unredeemed or redeemed phenyl group, or unsubstituted or substituted naphthyl group. R1: water Wi group or amino group. R2: When R1 is a hydroxyl group, it is an amino group; when R1 is an amino group, it is a hydroxyl group. R3: hydrogen, halogen, or alkyl group to C + ~,
Alkoxy group or hydroxyalkyl ether group. R4: A C2-6 hydroxyalkyl group or an ether thereof, or a C2-6 dihydroxyalkyl group or an ether thereof. R5: hydrogen, an alkyl group, a C2-6 hydroxyalkyl group or an ether thereof, or a C2-6 dihydroxyalkyl group or an ether thereof. X: hydrogen, Na1, and a cation such as Li1 or an organic amine. Y: oxygen, sulfur, or nitrogen. n: An integer from 0 to 1, provided that when Y is oxygen or sulfur, O: When Y is nitrogen, it is 1°m: 1 or 2°