JPS6045667B2 - recording liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel recording liquid, particularly a recording liquid suitable for an inkjet recording method.

2. Description of the Related Art Inks used for writing instruments (felt pens, fountain pens, etc.) have heretofore been known in which various dyes and pigments are dissolved or dispersed in a liquid medium consisting of water or other organic solvents.

The above-mentioned recording liquid is also used in the so-called inkjet recording method, which performs recording by ejecting the liquid in the recording head from the ejection orifice using vibration by a piezo vibrator, electrostatic attraction by applying high voltage, thermal energy, etc. It is known that

Writing instruments such as felt-tip fountain pens and inkjet recording liquids have many properties in common, such as the absence of clogging due to ink drying at the tip and good water resistance and light resistance of recorded images. Compared to writing instruments, inkjet recording liquids require conditions that are not present in writing instruments, such as ejection responsiveness and ejection stability when droplets are generated from minute orifices.

Conventionally, as recording liquids for stationery or inkjet recording, for example, JP-A-50-91427 and JP-A-51-90 have been used.
624, Special Publication No. 51-40484, Special Publication No. 52-1
No. 3126, Japanese Patent Publication No. 13127, 1983, Japanese Patent Publication No. 1983-
As shown in publications such as No. 95008, there are known dyes and pigments in which various dye pigments are dissolved or dispersed in aqueous or non-aqueous solvents.

Preferable conditions common to recording liquids for stationery and inkjet recording are (1) no clogging due to drying at the pen tip or orifice tip;

(2) Fast fixation on recording materials (paper, cloth, film, etc.) with little bleeding.

(3) The color tone of the recorded image is clear and the density is high.

(4) The recorded image has excellent water resistance and light resistance. (
5) Do not damage surrounding materials (containers, filters, etc.) of the recording liquid.

(6) Must be safe in terms of odor, toxicity, flammability, etc.

etc.

Furthermore, inkjet recording liquids must have liquid physical properties (viscosity, surface tension, electrical conductivity, etc.) that match the ejection conditions (driving voltage, driving frequency, ejection orifice shape and material, orifice diameter, etc.). Therefore, it is required to have long-term discharge stability. That is, it has good ejection responsiveness to form droplets in response to the driving frequency, a wide stable ejection margin against fluctuations in driving voltage and driving frequency, and when recording while the ejection orifice moves left and right as in a printer. The ejection orifice is required to have properties such as holding the recording liquid so that the recording liquid is not ejected during non-recording. In addition, in the case of color recording in cyan, magenta, yellow, and black, the color of the recording liquid changes even during long-term storage so that the recording liquid penetrates into the recording material quickly and does not bleed, and the desired color balance does not change. required not to do so. It is quite difficult to simultaneously satisfy the various characteristics described in the first half, and the conventionally known technology described above has this point. It was unsatisfactory.

Dyes and pigments used in this type of recording liquid are, for example, Japanese Patent Publications Nos. 13126-1982, 89534-1980, 95008-1980, 77706-1970, and 77706-1980. It is disclosed in publications such as No. 90624. However, in general, dyes such as direct dyes, acid dyes, and basic dyes have problems in the water resistance and light resistance of recorded images, and pigments have problems in that they have poor dispersion stability and are prone to clogging.
Furthermore, dyes cause molecular association in a liquid medium, resulting in a change in color tone, and pigments cause sedimentation, which reduces the concentration of dispersed pigments and disrupts the three-color balance. The present invention eliminates the drawbacks of the conventional examples mentioned above and satisfies ejection stability, long-term storage stability, fixing performance, image density, sharpness, water resistance and light resistance at the same time, and also eliminates odor, toxicity, flammability, etc. It is an object of the present invention to provide a recording liquid with excellent safety and high practicality, particularly a yellow recording liquid suitable for color recording. In other words, the present invention provides a recording liquid composed of a recording agent for forming a recorded image and a liquid medium for dissolving and/or dispersing the recording agent, in which the recording agent contains a water-soluble yellow dye. a yellow pigment with a molecular weight of 1000 to 10000 in the liquid medium.
There are also products characterized by containing 0 polymer dispersant and water.

That is, the present invention provides a yellow recording liquid useful for color recording, which has both the excellent water resistance and light resistance of pigments and the vivid color tone of dyes, and has excellent dispersion stability for long-term storage.

Although the reason is not clear, the composition of the present invention produces a synergistic effect in that the water resistance of the dye is significantly improved compared to when the dye is used alone, and the dispersion stability of the pigment is significantly improved compared to when no dye is present. Furthermore, the recording liquid of the present invention has extremely favorable properties such as reduced thixotropic properties and no change in color over time compared to the case where each dye or pigment is used alone. Preferred dyes in the present invention that exhibit such a remarkable synergistic effect are C.I. I. Direct dyes represented by Direct Yellow 8, 22, 26, 27, 87, C.I. I. Acid Yellow 1, 7, 11, 17, 23
, 44; I. Examples include basic dyes represented by Basic Yellow 1 and 11.

Similarly, the pigment preferably used in the present invention is C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 73, 74, 9
7,98,1301, Hansa Yellow, C.I. I
．． pigment yellow 12, 13, 14, 15, 16,
17,55,81,83, benzidine yellow, C.I. I. Condensed azo pigments represented by Pigment Yellow 93, 94, and 95, C.I. I. pigment yellow 23
An anthraquinone pigment represented by C. I. Anthrapyrimidine pigment represented by Pigment Yellow 108 (Pat Yellow 20), C.I. I. pigment yellow 1
The isoindolinone pigment represented by C.09, C.I. I. Pigment Yellow 120, an azo pigment represented by C.I. I. A chelate pigment represented by Pigment Yellow 117 is mentioned.

The dyes and pigments are C.I. I. E. Color value (JISZ-87
01) Both have a dominant wavelength of 550 to 590 nanometers,
Desirably, the stimulation purity is in the range of 73 to 83 percent and the brightness is in the range of 79 to 89 per cent.

In the recording liquid of the present invention, the preferred ratio of the dye to the pigment is in the range of 10:1 to 1:10.

The dispersant preferably used in the present invention has a molecular weight of 1000.
There are ~100,000 polymer dispersants. Examples of preferable polymeric dispersants include polyvinyl alcohol, polyvinylpyrrolidone, polyvinylpyridine, polyacrylates, polymethacrylates, all of which have the above molecular weight range.
Condensed naphthalene sulfonate, styrene-maleic acid copolymer, diisobutylene-maleic acid copolymer, polyethylene glycol, polypropylene glycol, polyoxyethylene-oxypropylene block polymer, styrene-(meth)acrylic acid, (meth)acrylic acid Ester-(meth)acrylate copolymer, -styrene-itaconate copolymer, itaconate-itaconate copolymer, vinylnaphthalene-maleate copolymer, vinylnaphthalene-(meth)acrylic acid These include copolymers, vinylnaphthalene-itaconate copolymers, etc., and derivatives thereof. The above polymers may further be copolymerized with monomers such as acrylonitrile, vinyl acetate, (meth)acrylamide, N-methylol (meth)acrylamide, vinyl chloride, vinylidene chloride, and ethylene, and these polymer dispersants Some of these are commercially available or can be easily synthesized by known polymerization methods. The amount of the dispersant added is preferably 1 to 300 weight percent, more preferably 5 to 20 weight percent based on the pigment content. As the liquid medium of the recording liquid of the present invention, water or a mixed system of water and a water-miscible organic solvent is used.

Examples of water-miscible organic solvents that are preferably used include methyl alcohol, ethyl alcohol, propyl alcohol, diacetone alcohol, furfuryl alcohol, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, and Ethylene glycol, tetraethylene glycol, 1,2,6 hexanetriol, thiodiglycol, glycerin, ethylene glycol, monomethyl ether, ethylene glycol monoethyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, triethylene glycol monomethyl ether , triethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, methyl carbitol acetate, ethyl carbitol acetate, diethanolamine, triethanolamine, formamide,
These include dimethylformamide, dimethylacetamide, morpholine, dimethylacetamide, N-methyl-2-pyrrolidone, 1,3 dimethyl-2-imidazolidinone, and the like. The preferred content of these water-miscible organic solvents is 5 to 8 percent by volume in the liquid medium, more preferably 10 to 5 percent.
Heel volume percentage.

In addition, to the recording liquid of the present invention, conventionally known viscosity modifiers, surface tension modifiers, PH modifiers, conductivity modifiers, binders (polymer vehicles), antifungal sterilizers, etc. may be added. I can do it. The recording liquid of the present invention is composed mainly of the above-mentioned components, and various methods can be employed for its preparation.

For example, a method is employed in which the above-mentioned components are blended and mixed and ground using a ball mill, roll mill, speed line mill, homomixer, sand grinder, or the like. still,
The pigment dispersion process is carried out in a state where the pigment is as highly concentrated as possible, and after the dispersion treatment, this is diluted with an aqueous liquid, so that the final viscosity of the ink is about 1 to 20 CpS1, preferably about Adjusted to 3-10CpS.

In the recording liquid prepared in this manner, pigment particles do not aggregate or settle even when stored for a long period of time in a low viscosity range.

This recording liquid can be used under (1) a wide range of recording liquid ejection conditions (driving voltage of the piezoelectric element,
It has liquid physical properties (viscosity, surface tension, electrical conductivity, etc.) that match the drive frequency, discharge orifice shape and material, discharge orifice diameter, etc.).

(2) Stable for long-term storage and does not cause clogging of inkjet devices.

(3) Fast and reliable fixing to the recording material (paper, film, etc.), and the dot periphery is smooth and does not bleed.

(4) The color tone of the formed image is clear and the density is high.

(5) The formed image has excellent water resistance and light resistance.
(6) Do not damage materials surrounding the recording liquid (container, connecting tube, sealing material, etc.).

(7) It has various characteristics such as low odor, toxicity, non-flammability, and excellent safety.

Here, the present invention will be explained in further detail by showing examples. In addition, the number of parts in the examples is the number of parts by weight.

Example 1 C. I. Pigment Yellow 125 partsC. I. Direct Yellow 83 parts polyacrylic acid (MW2OOO) 3 parts diethylene glycol 1 part ion exchange water
Marked part The above ingredients were placed in a ball mill and rotated for an hour to mix and grind.

The obtained dispersion liquid was subjected to an ultracentrifuge to remove coarse particles to obtain a yellow recording liquid. C. of recording liquid. I. The E color value was a dominant wavelength of 574 nanometers, an excitation purity of 79/cents, and a brightness of 83/'<:-cents. Using the recording liquid, T1 to T5 were examined using a recording apparatus having an on-demand recording head (discharge orifice diameter 50μ, piezoelectric vibrator drive voltage 60V, frequency 4KHz) that discharges the recording liquid using a piezoelectric vibrator. All experiments yielded good results.

(T1) Long-term storage stability of the recording liquid: Even after the above recording liquid was sealed in a glass container and stored at -300C and 60°C for 6 months, no precipitation of insoluble matter was observed, and the physical properties and color tone of the liquid did not change. I was bored.

(T2) Ejection stability: Continuous ejection was carried out for two dishes each in an atmosphere of room temperature, 5° C. and 140° C. Under all conditions, stable and high quality recording was possible from beginning to end.

(T3) Ejection responsiveness: Intermittent ejection every 2 seconds and ejection after being left for 2 months were investigated, and in both cases, stable and uniform recording was achieved without clogging at the orifice tip.

(T4) Quality of recorded images: The images recorded on the recording materials shown in Table 1 had high density and were clear.

After three months of exposure to outdoor light, the density reduction rate was less than 1%, and when immersed in water for 1 minute, there was no image smearing. (T5) Fixability on various recording materials; After printing on the following recording materials, the printed area was rubbed with a finger to determine the presence or absence of image shift and bleeding.

All of them exhibited excellent fixing properties with no image shift or blurring. Example 2 A recording liquid having the composition shown in the table below was prepared in the same manner as in Example 1, and T1 to T4 were examined in the same manner as in Example 1.

(In Table 2, the numbers in parentheses indicate the composition ratio)
. It also has an on-demand type multi-head (discharge orifice diameter 35μ, heating resistor resistance value 150Ω, drive voltage 30V, frequency 2KHz) that performs recording by applying thermal energy to the recording liquid in the recording head to generate droplets. The same study as in Example 1 was conducted using a recording device.

In all cases, the recorded images obtained had excellent light fastness and water resistance, clear color tone and high density, smooth dot periphery without bleeding or blurring, and good fixing properties.

Claims (1)

[Scope of Claims] 1. In a recording liquid composed of a recording agent for providing a recorded image and a liquid medium for dissolving and/or dispersing this recording agent, the recording agent contains a water-soluble yellow dye and a yellow pigment. A recording liquid comprising: a polymer dispersant having a molecular weight of 1,000 to 100,000 and water in the liquid medium. 2 C. of the dyes and pigments. I. E. All color values are dominant wavelength 570±20 nanometers and purity 78±5.
%, the recording liquid according to item 1, having a brightness in the range of 84±5%. 3 The ratio of the dye to the pigment is 10:1 to 1: by weight.
10. The recording liquid according to claim 1, which falls within the range of 10. 4. The recording liquid according to claim 1, wherein the dye and pigment contents are both in the range of 1 to 20 weight percent based on the total weight of the recording liquid. 5 The dye is C.I. I. Direct Yellow 8, 22, 26, 27, 87, C. I.
Acid Yellow 1, 7, 11, 17, 23, 44, C
．． I. The recording liquid according to claim 1, which is a dye selected from Basic Yellow 1 and 11. 6 The pigment is C.I. I. pigment yellow 1, 2, 3
,4,5,6,12,13,14,15,16,17,
23, 55, 73, 74, 81, 83, 93, 94, 9
5,97,98,108,109,117,120,1
The recording liquid according to claim 1, which is a pigment selected from among 30 pigments.