JPS6045668B2 - 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 inkjet recording methods.

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

Furthermore, in the so-called inkjet recording method, in which recording is performed by ejecting the liquid in the recording J head from the ejection orifice using vibration by a piezo vibrator, electrostatic attraction by applying a high voltage, thermal energy, etc., the above-mentioned recording liquid is used. known to be used.

Writing instruments such as felt pens and fountain pens have many properties in common with inkjet recording liquids, 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 a writing instrument, an inkjet recording liquid requires conditions that are not present in a writing instrument, such as ejection responsiveness and ejection stability when generating droplets from a fine orifice.

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. 52-11
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 the surrounding materials (containers, filters) 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, it is important to ensure that the recording liquid permeates the recording material quickly and without bleeding, and that the color of the recording liquid remains unchanged during long-term storage so that the desired color balance does not change. It is required that it does not change.

It is necessary to satisfy the above characteristics at the same time. This is extremely difficult, and the previously known techniques described above were unsatisfactory in this respect.

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. -90624 and other publications.

However, dyes such as direct dyes, acid dyes, and basic dyes generally 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, the dye causes molecular association in the liquid medium, causing a change in color tone.
In addition, pigments have the disadvantage that the concentration of dispersed pigments decreases due to sedimentation, which disrupts color balance. The present invention eliminates the above-mentioned drawbacks of the conventional example and simultaneously satisfies discharge stability, long-term storage stability, fixing performance, image density, clarity, water resistance, and light resistance, and furthermore, has low odor and toxicity, and is non-flammable. It is an object of the present invention to provide a recording liquid that is highly safe and highly practical, particularly a blue recording liquid suitable for color recording.

The present invention also provides a recording liquid composed of a recording agent for forming a recorded image and a liquid medium for dissolving and/or dispersing this recording agent, in which the recording agent contains a water-soluble blue dye and a blue pigment. and a molecular weight of 1000 in the liquid medium.
It is characterized by containing a polymer dispersant of 100,000 to 100,000 and water. That is, the present invention provides a blue 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 thixotropy and no color change 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 Blue 25, 41, 76
, 86, 106, 108; I
．． Acid blue 1, 9, 23, 74, 103, 112
An acidic dye represented by C. I. Basic blue 1, 3
Examples include basic dyes represented by:

Similarly, the pigment preferably used in the present invention is C.I. I. Examples include phthalocyanine pigments represented by Pigment Blue 15 and 16.

The dyes and pigments are C.I. I. E. Color value (JISZ-87
01) with a dominant wavelength of 460 to 500 nanometers,
Stimulus purity 55-65/mercent, brightness 29-3g/
Preferably within the mercent range.

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 copolymer These are polymers, vinylnaphthalene-itaconate copolymers, etc., and derivatives thereof. In addition to the above polymers, for example, acrylonitrile, vinyl acetate, (meth)acrylamide, N-methylol (meth)acrylamide, vinyl chloride, salts. Monomers such as vinylidene chloride and ethylene may be copolymerized.

Some of these polymeric dispersants are commercially available and can be easily synthesized by known polymerization methods. The amount of the dispersant added is preferably 1 to 3 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 triethylene. Glycol, tetraethylene glycol, 1,2,6 hexanetriol, thiodiglycol, glycerin, ethylene glycol monomethyl ether, ethylene diglycol 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, 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 in the liquid medium is 5 to 8 weight percent, more preferably 10 to 5 weight percent.

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.
The viscosity of the ink is finally adjusted to about 1-20 CpS1, preferably about 3-10 CpS.

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,
Liquid physical properties (viscosity, surface tension,
electrical conductivity, 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 the 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. Note that the numbers in the examples are parts by weight. Example 1 (
VVPW▼The above components were placed in a ball mill and mixed and ground by rotating the ball mill.

The obtained dispersion liquid was subjected to an ultracentrifuge to remove coarse particles, and a blue recording liquid was obtained. C. of recording liquid. I. E. The color values were a dominant wavelength of 482 nanometers, an excitation purity of 60%, and a brightness of 34%. Using the recording liquid, a recording device having an on-demand recording head (discharge orifice diameter 50μ, piezoelectric vibrator drive voltage 60V, frequency 4KHz) that discharges the recording liquid by a piezoelectric vibrator was used to study T, to T5. We obtained good results in all cases. Long-term storage stability of T1 recording liquid: Even after the above recording liquid was sealed in a glass container and stored at -30°C and 60°C for 6 months, no precipitation of insoluble matter was observed, and there was no change in the physical properties or color tone of the liquid. I was bored.

T2 ejection stability: Continuous ejection was performed for 24 hours at room temperature in an atmosphere of 5°Cl4O'C, and stable high-quality recording was possible from beginning to end under all conditions.

T3 ejection response: Intermittent ejection every 2 seconds and ejection for 2 months: Ejection after standing was investigated, and in both cases, stable and uniform recording was achieved without clogging at the orifice tip.

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

The rate of decrease in density after exposure to outdoor light was less than 1%, and when immersed in water for 1 minute, there was no image bleeding at all. T5 Fixability on various recording materials;
After one or two prints using the following recording material, the printed area was rubbed with a finger to determine the presence or absence of image shift and smearing.

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. (Numbers indicate composition ratios).

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.

Further, even when the recording liquid was stored for a long period of time, the pigment particles did not aggregate or settle, and stable discharge was possible. All recording liquids have a dominant wavelength of 460 to 500 nanometers and an excitation purity of 55.
~65% brightness ranged from 29-39%.

Claims (1)

[Scope of Claims] 1. 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, wherein the recording agent contains a water-soluble blue dye and a blue 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. Both E color values are
The recording liquid according to claim 1, which has a dominant wavelength of 480±20 nanometers, an optical purity of 60±5 percent, and a brightness of 34±5 percent. 3 The ratio of the dye to the pigment is 10:1 to 1:1 by weight.
The recording liquid according to claim 1, which is in the range of 0. 4. The recording liquid according to claim 1, wherein the contents of the dye and the pigment 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 Blue 25, 41,
76, 86, 106, 108, C. I. Acid Blue 1, 9, 23, 74, 103, 112, C. I. The recording liquid according to claim 1, which is a dye selected from Basic Blue 1 and 3. 6. The recording liquid according to claim 1, wherein the pigment is phthalocyanine blue (C.I. Pigment Blue 15, 16).