JPH0366768A - Ink and recording method using it - Google Patents

Abstract

PURPOSE:To obtain the subject ink having a high printing density, excellent in color and free from clogging of a printer by dispersing carbon black in a liquid medium containing water, a polyvalent alcohol and ethanol and blending a phthalocyanine dye therewith. CONSTITUTION:In a liquid medium composed of water, a polyvalent alcohol [e.g. (di)ethylene glycol] and ethanol as the main components, carbon black is dispersed and a phthalocyanine dye (preferably C.I. acid blue 185, 279, C.I. direct blue 86, 67, 189, 199, C.I. reactive blue 14, 15, 18, 21, 25, 38, 41, 63, 71, 72, 77, 105, 116, 140, 190, 227 or 228) is blended therewith, preferably in an amount of 0.5-2wt.%, thus obtaining the objective ink.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an ink (recording liquid) suitable for various recording instruments and recording devices such as writing implements and printers, and an ink that is ejected from an orifice of a recording head. It relates to a recording method for recording.

(Prior art) The inkjet recording method generates less noise during recording, is easily compatible with color printing, and can obtain high-resolution recorded images at high speed by using a highly integrated head. It has the advantage of

In the inkjet recording method, an ink in which various water-soluble dyes are dissolved in water or a mixture of water and an organic solvent is used.

However, when water-soluble dyes are used, the light resistance of recorded images often becomes a problem because these water-soluble dyes inherently have poor light resistance.

Furthermore, since the ink is water-soluble, the water resistance of recorded images often becomes a problem. That is, when the recorded image is exposed to rain, sweat, or drinking water.

Recorded images may blur or disappear.

Therefore, in order to solve the above problems of light resistance and water resistance,
Pigment inks have been proposed. As an example of studying the dispersion stability for the practical use of pigment ink, see JP-A-61
-2354 '78 Publication, JP-A-61-246271
JP-A-62-1.16678, etc., and examples of studies that consider preventing ink from solidifying at the tip of a pen or orifice include JP-A-56-41261;
Examples include JP-A-62-101672.

Further, JP-A-56-147859 describes an inkjet recording method using pigment ink.

(The problem that the invention is trying to solve) However,
As mentioned above, when pigment ink using conventional carbon black is used for inkjet recording, the fastness of printed matter is significantly improved compared to those using dye ink. A problem arose in that the color properties and density of printed matter, which are characteristics of recording, were inferior to those printed using dye ink.

Furthermore, Japanese Patent Laid-Open No. 62-39676 discusses the chromaticity of black ink with good color properties. According to this, dyes that satisfy J'a°゛+b°'≦2 (CIE L"a"b' color system) produce the optimal black, but in the case of pigment inks, those with a strong reddish tinge However, there are very few black pigments that satisfy the above formula. In addition, increasing the pigment concentration can be considered to increase the printing density, but when using high-concentration pigment ink in an inkjet printer,
This had the disadvantage of causing a common problem in discharge stability.

Furthermore, when using dispersion systems such as pigment inks for inkjet recording, preventing solidification at the tip of the head due to long-term storage is an important technical issue, and the composition of the ink must be carefully designed to ensure reliable pigment ink composition. This is an important point above.

Furthermore, although some conventional pigment inks have excellent ejection properties in a relatively short period of time, ejection becomes unstable if the driving conditions of the print head are changed or continuous ejection is performed for a long period of time. This causes the problem that the discharge stops.

Therefore, an object of the present invention is to provide an ink and a recording method using the ink that can eliminate the problems of the prior art described above and that can always perform stable ejection even when driving conditions change or when used for a long time. It is in.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides an ink comprising a phthalocyanine dye dispersed in a liquid medium containing water, a polyhydric alcohol, and ethanol as main components, and an ink that is characterized by containing a phthalocyanine dye. This is a recording method characterized by applying energy to eject droplets from micropores.

(Function) By adding a small amount of phthalocyanine dye to ink that contains carbon black as a pigment, it is possible to eliminate the reddish characteristic of carbon black and create a jet black color, as well as increase the density of the black color. It's coming. It is also possible to solve the problem of solidification of ink at the tip of the head and the problem of ejection stability by adjusting the composition of the I-liquid medium.

(Preferred Embodiments) Next, the present invention will be explained in more detail by citing preferred embodiments. The liquid medium used in the ink of the present invention mainly contains water, polyhydric alcohol, and ethanol. Preferably, deionized water is used. In addition, polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, butylene glycol,
II2.6-hexandriol, thiodiglycol,
Alkylene glycols in which the alkylene group has 2 to 6 carbon atoms such as hexylene glycol, glycerin, etc. are used, and these polyhydric alcohols have a
It is preferable to use it in an amount accounting for 20 to 50% by weight or more, preferably 20 to 50% by weight. If the amount of polyhydric alcohol used is too small, there will be a problem of solidification of the ink at the tip of the ejection nozzle, while if it is too large, there will be problems such as dryness of the ink.

Further, the ethanol used in the present invention is preferably used in an amount of 5% by weight or more, preferably 5 to 10% by weight in the liquid medium. If the amount of ethanol used is too small, there will be problems with ejection stability, while if it is too large, there will be problems with the quality of printed matter.

In addition, as long as the above-mentioned polyhydric alcohol and ethanol are present in a predetermined amount, other organic solvents such as methyl alcohol,
n-propyl alcohol, isopropyl alcohol, n
-butyl alcohol, sec-butyl alcohol, te
Alkyl alcohols having 1 to 4 carbon atoms such as rt-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketone or keto alcohols such as acetone and diaceto alcohol; ethers such as tetrahydrofuran and dioxane; ethylene glycol monomethyl (or ethyl) ether,
diethylene glycol methyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; N
-Methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. can be added.

As the carbon black used in the present invention, any commercially available carbon black can be used, and carbon black that has been previously surface-treated with a surfactant or polymeric dispersant, or grafted carbon can also be used, and is not particularly limited.

As a method for dispersing these carbon blacks in the above seven liquid media, conventionally known pigment dispersion techniques can be used as they are. For example, if the pigment has been previously dispersed, it can be dispersed in a liquid medium using a normal stirrer, or the pigment can be mixed with a surfactant, a polymeric dispersant, etc. at a high concentration in water or the liquid medium. There are two methods: dispersion treatment to form a pigment concentrate, which is then dispersed in a liquid medium at an appropriate degree of degree, and furthermore, a method in which all components are blended as an ink composition and dispersion treatment is performed in this state. In either case, coarse pigment particles should be removed by centrifugation, filtration, etc. before the ink is finally made into ink so that no coarse pigment particles remain in the ink.

The dispersing machine used for dispersing the pigment may be any commonly used dispersing machine, such as a ball mill, a roll mill, a sand mill, etc. Among these, high-speed sand mills are preferred, and examples include super mills, sand grinders, bead mills, agitator mills, grain mills, dyno mills, burr mills, and cobol mills (all trade names).

In the present invention, methods for obtaining a pigment having a desired particle size distribution include reducing the size of the grinding media of the dispersion machine, increasing the filling rate of the grinding media, lengthening the processing time, and slowing down the discharge speed. Methods such as pulverization and classification using a filter or centrifuge are used. Also, a combination of these methods may be used.

The amount of carbon black added varies depending on the type of carbon black, but - 3 to 20% by weight of the ink is added to the film.
, preferably in a proportion ranging from 3 to 12% by weight.

Water-soluble resins used for pigment dispersion include, for example, proteins such as gelatin, albumin, and casein, natural rubbers such as gum arabic and gum tragacanth, glucosides such as saponin, methylcellulose, carboxycellulose, and human U-xymethylcellulose. Cellulose derivatives, lignin sulfonic acid, natural polymers such as shellac, polyacrylic acid, polyethylene-acrylic acid copolymers, styrene-acrylic acid-acrylic acid alkyl ester copolymers, styrene-maleic acid copolymers, Styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-
Acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer or salt thereof, sodium β-naphthalenesulfonic acid formalin condensate Salt 1. Examples include polymeric dispersants such as anionic polymers such as phosphates, nonionic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene glycol.

In addition, in order to improve the solubility and stability of these resins, it is preferable to add amines during dispersion. For example, amines added to the dispersion include monoethanolamine, jetanolamine, and triethanol. Organic amines such as amines, aminomethylpropanol, and ammonia are preferred.

In addition, as surfactants, anionic surfactants such as fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, alkylaryl sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, There are nonionic surfactants such as polyoxyethylene sorbitan alkyl esters,
One or more of these can be appropriately selected and used.

The amount used varies depending on the dispersant, but it is preferably from 0 to 5% based on the total amount of the ink.

On the other hand, in order to obtain an ink with desired physical properties, a pH adjuster, an antifoaming agent, a preservative, etc. can be added.

In the present invention, a phthalocyanine dye is added to the ink prepared as described above. Addition of these phthalocyanine dyes improves the dispersion stability of the pigment, and the black color after printing becomes jet black, allowing beautiful black printing with high density.

Examples of the phthalocyanine dyes used include known dyes,
For example, C. I. Acid Blue 185.279, C1
Lda([/kutoblue86.67.189.199, C
．． I. Reactive Blue 14, +5.18.21.2
538.4m, 63.7], 72.77.105.11
6.140°190.227.228 is preferable, but not limited to these. The amount of the phthalocyanine dye added is preferably in the range of 0.5 to 2.0% by weight in the ink; if the phthalocyanine dye is too toxic, it will be difficult to eliminate the reddish color when using carbon black alone; ,
Too much carbon is not preferable because it causes the color tone of the print to deviate from the natural black and becomes bluish, and also causes a decrease in fastness such as light fastness and water resistance of the print.

Note that these phthalocyanine dyes may be added at the time of dispersing the carbon black, or may be added before or after the dispersion, and are not particularly limited.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

Example 1 Carbon black (MCF-88, made by Mitsubishi Kasei) 5 parts Direct Blue 199 (made by Bayer) 1.5 parts Stylish-acrylic acid copolymer (acid value X75, average molecular weight 12,000) 0.6 Part ethanolamine 0.1 part Glycerin 10 parts Diethylene glycol 10 parts Ethylene glycol
5 parts ethanol
7 parts Pure water 608 parts The above ingredients were mixed and subjected to a dispersion treatment using a bar mill (manufactured by Ashizawa ■) under the following conditions.

Glass beads 9 sizes = 0.8 to 1, 2mm diameter meso
A: 50% (volume) Emetic rate: 100 ml/min. Coarse particles were further removed by centrifugation treatment (2 times, OOORPM, 15 minutes) to obtain the ink of the present invention.

Example 2 An ink of the present invention was obtained in the same manner as in Example 1 except that 1.5 parts of Direct Blue 86 (manufactured by Ciba Geigy) was used in place of the dye of Example 1.

Example 3 An ink of the present invention was obtained in the same manner as in Example 1 except that 1.5 parts of Reactive Blue 14 (manufactured by Mitsubishi Kasei) was used in place of the dye of Example 1.

Example 4 5 parts of carbon black (MA-100, manufactured by Mitsubishi Kasei) 1.5 parts of Direct Blue 199 (manufactured by Bayer) α-methylstyrene-styrene-acrylic acid copolymer (
Acid value 195, average molecular weight 17,000) 0.6 parts ethanol 5 parts aminomethylpropanol 0.5 parts glycerin
5 parts polydiethylene glycol (PE
G300) 5-part diethylene glycol
100 parts Niracol B1-9E (manufactured by Nikko Chemicals) 0.5 parts Pure water 72.5 parts The above components were mixed and subjected to dispersion treatment under the following conditions using a sand grinder (manufactured by Igarashi Kikai ■) to obtain Example 1. A black ink of the present invention was obtained by performing the same centrifugal treatment as described above.

Zirconium beads 1: Size of zirconium bead media: 1 mm diameter Mezoa = 50% (volume) Holding time: 5 hours Comparative example 1 In Example 1, the dye was excluded, and the amount of carbon black was reduced to 6 An ink of a comparative example was obtained in the same manner as in Example 1, except that the ink was adjusted to 50%.

Comparative Example 2 A comparative ink was obtained in the same manner as in Example 2 except that the dye was changed to Acid Blue 9 (manufactured by Orient Chemical Co., Ltd.).

Comparative Example 3 Example 1 except that ethanol was excluded from Example 1
An ink of a comparative example was obtained in the same manner as described above.

Comparative Example 4 An ink of a comparative example was obtained in the same manner as in Example 1 except that the polyhydric alcohol was excluded.

Using each of the above inks, a recording device with an on-day multi-head (BJ 130, Canon ■
The following study was conducted using the following:

A print sample made using the above ink with T1.= (light resistance) was exposed to a xenon fade meter (black panel 63°C, humidity 75%) for 100 hours, and the change in chromaticity before and after treatment (color difference: before and after treatment) CIE L″a″b.

Measure the distance on the chromaticity coordinates of the change in chromaticity according to the colorimetric method.

(Water Resistance) A commercially available water-based highlighter pen was used to overwrite the printed matter from the top, and the degree of bleeding due to rubbing of the printed matter was examined and classified into three levels.

○: No bleeding △: Slight bleeding ×: Severe bleeding The printed matter was measured using a Macbeth densitometer (RD 91g).
The values of 2+(b'')', am, and bll are shown.

For clogging when reprinting after stopping, fill the printer with the specified ink, print alphanumeric characters continuously for 10 minutes, then stop printing and remove the cap. After leaving it for 10 minutes without doing anything, print the alphanumeric characters again and judge whether there are any defects such as blurred or missing characters (20"" ± 5°, 50 ± 10% RH) )6 0・-No defective parts from the 1st character △ Partially faded or chipped from the 2nd character × Knee character cannot be printed at all Perform continuous ejection at 5°C and 40″C, and calculate the time during which non-ejection occurs. Measured at 5°C for up to 24 hours and at 40°C for 4 hours.
Measurements were carried out for up to 8 hours.

The evaluation results are shown in Table 1 below. Regarding the evaluation in the table, for the light resistance of T1, the results of each color difference are
, the reflection density of the printed matter is described.

After filling the printer with the specified ink and printing alphanumeric characters continuously for 10 minutes, stop printing, leave the printer without the cap for 4 days, perform the operation to recover from the nozzle clogging, and check the number of times. It was determined whether normal printing without blurring or missing characters was possible using the following operations (20°±5", 50±
lO%RH).

○: Normal printing is possible after 1 to 10 recovery operations. △: Normal printing is possible after 10 or more recovery operations. , it is possible to provide an ink with excellent storage stability.

Claims (6)

[Claims] (1) An ink comprising carbon black dispersed in a liquid medium mainly composed of water, polyhydric alcohol, and ethanol, which is characterized by containing a phthalocyanine dye. (2) The dye is C.I. I. acid blue 185, 279
,C. I. Direct Blue 86, 67, 189, 19
9.C. I. Reactive blue 14, 15, 18, 2
1, 2538, 41, 63, 71, 72, 77, 105
, 116, 140, 190, 227, and 228. (3) The ink according to claim 1, wherein the dye content is 0.5 to 2% by weight. (4) The ink according to claim 1, wherein the content of polyhydric alcohol is 10% by weight or more. (5) The ink according to claim 1, wherein the ethanol content is 5 to 10% by weight. (6) Recording characterized by applying thermal energy to ink containing carbon black and phthalocyanine dye in a liquid medium mainly composed of water, polyhydric alcohol, and ethal and ejecting it as droplets from micropores. Method.