JPH0768480B2 - Ink and recording method using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ink (recording liquid) suitable for various recording devices such as a writing instrument and a printer, a recording apparatus, and an inkjet recording method using the ink.

(Prior Art) The ink jet recording system produces less noise during recording, is easy to colorize, and uses a highly integrated head to obtain a high-resolution recorded image at high speed. It has the advantage of

In the ink jet recording system, various types of water-soluble dyes dissolved in water or a mixed liquid of water and an organic solvent are used as ink.

However, when a water-soluble dye is used, these water-soluble dyes are originally inferior in light resistance, so that the light resistance of a recorded image often becomes a problem.

Further, since the ink is water-soluble, the water resistance of the recorded image often becomes a problem. That is, when the recorded image is exposed to rain, sweat, or water for eating or drinking, the recorded image is blurred or
It may disappear.

Therefore, in order to solve the above problems of light resistance and water resistance,
Pigment ink proposals have been made. As an example of studying dispersion stability for practical use of pigment ink, Japanese Patent Laid-Open No. 61-
235478, JP 61246271, JP 62-11
6678 and the like, and as an example of studying prevention of solidification of ink at the tip of a pen or an orifice, Japanese Patent Laid-Open No. 56-
41261, JP-A-62-101672 and the like can be mentioned.

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

(Problems to be Solved by the Invention) However, when a conventional pigment ink using carbon black is used for ink jet recording, the robustness of the printed matter is significantly improved as compared with that using the dye ink. As described above, subsequent research has caused a problem that the color characteristics and density of the printed matter, which are characteristic of ink jet recording, are inferior to those printed using the dye ink.

Further, JP-A-62-39676 discusses the chromaticity of black ink having good colorability. According to this Although the dye satisfying the above condition is the optimum black color, most of the pigment inks have a strong reddish color, and very few black pigments satisfy the above formula. Further, it is conceivable to increase the pigment concentration in order to increase the print density, but when a high-concentration pigment ink is used in an ink jet printer, there is a drawback that the ejection stability is significantly impaired.

Further, when using a dispersion system called pigment ink for inkjet recording, prevention of solidification at the head tip by leaving it for a long time is an important technical issue, and the composition of the ink is important in designing a reliable pigment ink. This is an important point.

Further, among the conventional pigment inks, although the ejection property is excellent in a relatively short time, the ejection becomes unstable when the driving conditions of the recording head are changed or the continuous ejection is performed for a long time. Finally, there is a problem that ejection is stopped.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an ink and a recording method using the same, which are capable of always performing stable ejection even when the driving conditions are changed and the ink is used for a long time. It is in.

(Means for Solving Problems) The above object is achieved by the present invention described below.

That is, the present invention relates to an ink obtained by dispersing carbon black in a liquid medium containing water, a polyhydric alcohol and ethanol as a main component, and an ink characterized by containing a phthalocyanine dye, and an inkjet recording using the same. Is the way.

(Function) By adding a small amount of a phthalocyanine dye to an ink containing carbon black as a pigment, it is possible to eliminate the redness peculiar to carbon black to give a jet black color and increase the density as black. .
Further, by adjusting the composition of the liquid medium, it is possible to solve the problems of solidification of ink at the tip of the head and the problems of ejection stability.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

The liquid medium used in the ink of the present invention contains water, polyhydric alcohol and ethanol as main components, and deionized water is preferably used as water. As the polyhydric alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, butylene glycol,
Alkylene glycols such as 1,2,6-hexanetriol, thiodiglycol, and hexyleneglycol having an alkylene group of 2 to 6 carbon atoms and glycerin are used. These polyhydric alcohols are used in a liquid medium. 20% by weight
Above, it is preferable to use in an amount of preferably 20 to 50% by weight. If the amount of polyhydric alcohol used is too small, there is a problem of solidification of the ink at the tip of the ejection nozzle, while if it is too large, there is a problem of ink drying property.

The ethanol used in the present invention is 5% by weight in the liquid medium.
Above, it is preferable to use in an amount of preferably 5 to 10% by weight. If the amount of ethanol used is too small, there is a problem of ejection stability, while if it is too large, there is a problem of print quality of the printed matter.

Also, as long as the above 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, tert-
Butyl alcohol, isobutyl alcohol, etc. has 1 carbon atom
To 4 alkyl alcohols; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetoalcohol; ethers such as tetrahydrofuran and dioxane; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl ( Or lower alkyl ethers of polyhydric alcohols such as ethyl) ether and triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. may be added. I can.

As the carbon black used in the present invention, any commercially available carbon black can be used, and one which is previously surface-treated with a surfactant or a polymer dispersant, or graft carbon can also be used, and is not particularly limited.

As a method for dispersing these carbon blacks in the liquid medium, a conventionally known pigment dispersion technique can be used as it is. For example, when it has been previously subjected to a dispersion treatment, it can be dispersed in a liquid medium with an ordinary stirrer, and a pigment can be dispersed at a high concentration in water or the liquid medium together with a surfactant or a polymer dispersant. Examples of the method include a method in which the pigment concentrate is treated to disperse the pigment concentrate in a liquid medium at an appropriate concentration, and further, all components as an ink composition are mixed and dispersed in this state. In any case, the coarse particles should be removed by centrifugal separation or filtration before finally being made into an ink so that the coarse particles of the pigment do not remain in the ink.

The disperser used for dispersing the pigment may be any disperser that is generally used, and examples thereof include a ball mill, a roll mill, and a sand mill. Among them, a high speed type sand mill is preferable, and examples thereof include a super mill, a sand grinder, a bees mill, an agitator mill, a grain mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).

In the present invention, as a method for obtaining a pigment having a desired particle size distribution, the size of the pulverized media of the disperser is reduced, and the filling rate of the pulverized media is increased. Also, the processing time is lengthened and the ejection speed is slowed. After crushing, a method such as classification with a filter or a centrifuge is used. Moreover, the combination of those methods is mentioned.

The amount of these carbon blacks added varies depending on the type, but generally 3 to 20% by weight in the ink,
It is preferably used in a proportion of 3 to 12% by weight.

As the water-soluble resin used for pigment dispersion, for example, gelatin, albumin, protein such as casein, gum arabic, natural rubber such as gum tragacanth, glucosides such as saponin, methylcellulose, carboxycellulose, cellulose derivative such as hydroxymethylcellulose, Natural polymers such as lignin sulfone hydrochloride, shellac,
Polyacrylic acid, styrene-acrylic acid copolymer, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, 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 salts thereof, β -Naphthalenesulfonic acid formalin condensate sodium salt, anionic polymer such as phosphate, polyvinyl alcohol, polyvinylpyrrolidone,
Examples thereof include polymer dispersants such as nonionic polymers such as polyethylene glycol. Further, for the purpose of improving the solubility and stability of these resins, it is preferable to add an amine at the time of dispersion. For example, as amines added to the dispersion liquid, monoethanolamine, diethanolamine,
Organic amines such as triethanolamine, aminomethylpropanol and ammonia are preferred.

As the surfactant, fatty acid salts, higher alcohol sulfate ester salts, liquid fatty acid sulfate ester salts, anionic surfactants such as alkylallyl sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, There are nonionic surfactants such as polyoxyethylene sorbitan alkyl esters,
These 1 type, or 2 or more types can be appropriately selected and used.
The amount used varies depending on the dispersant, but is preferably 0.01 to 5% by weight with respect to the total amount of the ink.

On the other hand, a pH adjusting agent, a defoaming agent, an antiseptic agent and the like can be added in order to obtain an ink having desired physical properties.

In the present invention, the phthalocyanine dye is added to the ink prepared as described above. By adding these phthalocyanine dyes, the dispersion stability of the pigment is improved, and the black color after printing becomes jet black, which enables beautiful and high-density printing as black.

Examples of phthalocyanine dyes used include known dyes,
For example, CI Acid Blue 185, 279, CI Direct Blue 86, 67, 189, 199, CI Reactive Blue 14,
15, 18, 21, 25, 38, 41, 63, 71, 72, 77, 105, 116,
140, 190, 227, 228 are preferred, but not limited to. The addition amount of the phthalocyanine dye is 0.
The range of 5 to 2.0% by weight is preferable, and when the amount of the phthalocyanine dye is too small, it is difficult to erase the reddishness when carbon black is used alone. It is not preferable because it becomes bluish and the fastness of the printed matter such as light resistance and water resistance is deteriorated.

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

(Examples) Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on weight.

Example 1 Carbon black (MCF-88, manufactured by Mitsubishi Kasei) 5 parts Direct Blue 199 (manufactured by Bayer) 1.5 parts Styrene-acrylic acid copolymer (acid value 175, average molecular weight 1
2,000) 0.6 part Ethanolamine 0.1 part Glycerin 10 parts Diethylene glycol 10 parts Ethylene glycol 5 parts Ethanol 7 parts Pure water 60.8 parts The above components are mixed and dispersed using a pearl mill (Ashizawa Co., Ltd.) under the following conditions: It was

Grinding media: Glass beads Grinding media size: 0.8 to 1.2 mm diameter Grinding media filling rate: 50% (volume) Discharge rate: 100 ml / min. Coarse particles are removed by centrifugal separation (20,000 RPM, 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 instead 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 Carbon black (MA-100, manufactured by Mitsubishi Kasei) 5 parts Direct Blue 199 (manufactured by Bayer) 1.5 parts α-methylstyrene-styrene-acrylic acid copolymer (acid value 195, average molecular weight 17,000) 0.6 parts Ethanol 5 parts Aminomethyl propanol 0.5 parts Glycerin 5 parts Polydiethylene glycol (PEG300) 5 parts Diethylene glycol 10 parts Nikkor B1-9EX (manufactured by Nikko Chemicals) 0.5 parts Pure water 72.5 parts Sand grinder (Igarashi Machinery Co., Ltd.) (4) was subjected to a dispersion treatment under the following conditions, and the same centrifugal treatment as in Example 1 was performed to obtain a black ink of the present invention.

Grinding media: Zirconium beads Size of grinding media: 1 mm diameter Filling ratio of grinding media: 50% (volume) Grinding time: 5 hours Comparative Example 1 Except for the dye in Example 1 except that the amount of carbon black was 6 parts In the same manner as in Example 1, an ink of Comparative Example was obtained.

Comparative Example 2 An ink of Comparative Example 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 omitted in Example 1.
An ink of Comparative Example was obtained in the same manner as in.

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

Recording device having an on-demand type multi-head using each of the above inks (BJ130, Canon Inc.)
The following studies were carried out using

T1; Robustness of printed matter (lightfastness) A printed sample made using the above ink was used as a xenon fade meter (black panel 63 ° C, humidity).
75%) for 100 hours, and the change in chromaticity before and after the treatment (color difference; the distance on the chromaticity coordinate of the change in chromaticity by the CIE L ^* a ^* b ^* colorimetric method before and after the treatment) is measured.

(Water resistance) Overwriting was performed from the top of the printed matter with a commercially available water-based fluorescent pen, and the degree of bleeding due to the rubbing of the printed matter was examined and classified into three stages.

◯: No bleeding Δ: Slightly bleeding x: Severely bleeding T2: Optical density of printed matter The printed matter was measured using a Macbeth densitometer (RD918).

T3; Color of printed matter Color of printed matter was measured with a color difference meter (CA35), and (a ^* ) ²
The values of + (b ^* ) ² , a ^* , and b ^* are shown.

T4: Clogging during reprinting after pausing printing For clogging during reprinting after pausing printing, fill the printer with the specified ink, print alphanumeric characters continuously for 10 minutes, and then stop printing. After leaving for 10 minutes without the cap, etc., the alphanumeric characters are printed again and judged by the presence or absence of defective parts such as faintness of letters and cracks (leave at 20 ° ± 5 °, 50 ± 10% RH ).

○: No defect from the first character △: Part of the first character is scratched or chipped ×: The first character cannot be printed at all T5; Recovery from clogging during reprinting after long-term printing stop Printer is filled with specified ink Then, after printing the alphanumeric characters for 10 minutes continuously, stop the printing, leave it for 4 days without the cap, recover the nozzle clogging, and repeat how many times the character is blurred. It was judged whether normal printing without chipping was possible (20 ° ± 5 °, 50 ± 10% RH).

○: Normal printing is possible with 1 to 10 recovery operations △: Normal printing is possible with 10 or more recovery operations ×: Recovery is not possible with recovery operation T6; Discharge stability 5 ℃, 40 ℃ Continuous ejection was performed and the time at which ejection failure occurred was measured. The measurement was performed at 5 ° C for up to 24 hours and at 40 ° C for up to 48 hours.

The evaluation results are shown in Table 1 below. Regarding the evaluations in the table, the results of the respective color differences were described for the light resistance of T1, and the reflection density of the printed matter was described for T2.

(Effects) According to the present invention, it is possible to submit an ink that is excellent in the robustness of the printed matter, and can provide a printed matter having a high print density and good color characteristics, and it is possible to consistently eject the ink even when ejected for a long time. It is possible to provide an ink which is obtained and which is less likely to cause clogging of the printer and has excellent storage stability.

Claims (4)

[Claims] 1. An ink obtained by dispersing carbon black in a liquid medium containing water, a polyhydric alcohol and ethanol as a main component, which contains a phthalocyanine dye. 2. A dye is CI Acid Blue 185, 279, C.I.
I. Direct Blue 86, 67, 189, 199, CI Reactive Blue 14, 15, 18, 21, 25, 38, 41, 63, 71, 72, 7
The ink according to claim 1, wherein the ink is at least one selected from the group consisting of 7, 105, 116, 140, 190, 227, and 228. 3. The ink according to claim 1, wherein the content of the dye is 0.5 to 2% by weight. 4. An ink jet recording method, wherein droplets of the ink according to any one of claims 1 to 3 are formed, and recording is performed using the droplets.