JPH01204979A - Recording liquid and inkjet recording method using the same - Google Patents

Abstract

PURPOSE:To realize stable delivery of a recording fluid even under variable drive conditions or during long-term service, by dispersing a pigment wherein pigment particles of at least a specified diameter account for at most a specified proportion of the total pigment in a liquid medium consisting mainly of water. CONSTITUTION:In a recording fluid comprising a dispersion of a pigment in a liquid medium consisting mainly of water, pigment particles having a diameter of 0.6mum or more account for 10vol.% or less of the total pigment. If a larger amount of coarse particles are present in an ink, a change occurs in the ink dispersion when thermal energy is applied to the ink with a heating head, so that a foreign substance will deposit on the heated surface. An ink containing a large amount of fine pigment particles produces a dispersion stable even when thermal energy is applied, so that it hardly causes deposition. Accordingly, the use of an ink containing a pigment having the above-mentioned particle diameter can realize stable delivery even under variable drive conditions or during long-term service.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a recording liquid suitable for various recording instruments and recording devices such as writing instruments and printers, and further relates to a recording liquid suitable for various recording instruments and recording devices such as writing instruments and printers. The present invention relates to a recording method in which recording is performed by flying droplets of water.

[Conventional technology]

The inkjet recording method has the advantage that it generates less noise during recording, is easily adaptable to large amounts of power and color, and can obtain high-resolution recorded images at high speed.

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, water resistance of recorded images often becomes a problem. That is, if a recorded image is exposed to rain, sweat, or drinking water, the recorded image may smudge or disappear.

Therefore, pigment inks have been proposed to solve the above problems of light resistance and water resistance. An example of studying dispersion stability for practical use of pigment ink is JP-A-61-2.
No. 35478, Japanese Patent Application Laid-open No. 61-246271,
JP-A-62-116678, etc. are cited, and examples of studies that consider prevention of solidification of ink at the tip of a pen or orifice include JP-A-56-41261 and JP-A-62.
-101672 publication etc. are mentioned.

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

[Problem that the invention seeks to solve]

However, when conventional pigment inks are used in inkjet printers that use thermal energy as a droplet ejection source, there is a drawback in that ejection stability is significantly impaired.

In addition, although some conventional pigment inks have excellent ejection properties in a relatively short time, it is necessary to change the driving conditions of the recording head,
When continuous ejection is performed for a long period of time, the ejection becomes unstable and eventually the ejection stops.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a recording liquid and a recording method using the same, which can eliminate the problems of the prior art described above and can always perform stable ejection even when driving conditions vary or when used for a long time. There is a particular thing.

[Means and effects for solving the problems] The above objects are achieved by the present invention as described below.

That is, in the present invention, 8, in a recording liquid formed by dispersing pigments in a liquid medium, pigments with a particle size of 0.6 μm or more account for 10 of the total pigments.
% (volume %) or less, and is a recording method in which energy is applied to the recording liquid to eject droplets from fine holes.

As a result of various studies on pigment inks suitable for use in inkjet printers that use thermal energy as a droplet ejection source, the present inventor found that pigment particles with a large particle size, particularly 0.6μ
If a large number of coarse particles with a size of 5.0 m or more (preferably 3 μm or less) are present in the ink, some changes will occur in the ink dispersion system when thermal energy is applied to the ink on the heating head, and foreign matter will appear on the heat-applying surface. On the other hand, fine pigment particles, especially 0.6 μm or more (preferably 0.00 μm or more)
The present invention was completed based on the discovery that the dispersion of ink containing many microparticles (1 μm or larger) is stable even when thermal energy is applied, and even if the particles adhere to a heat-active surface, precipitation of foreign matter is unlikely to occur. That's what I did.

The present invention will be explained in detail below.

As the pigment used in the present invention, all conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments, and polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthaloni pigments. Formula pigments, dye lakes such as basic dye lakes and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, titanium oxide, iron oxide, carbon black, etc. Examples include inorganic pigments.

Furthermore, any pigment not listed in Color Intex can be used as long as it can be dispersed in the aqueous phase.

Furthermore, it is of course possible to use the above-mentioned pigments surface-treated with surfactants, polymeric dispersants, etc., and grafted carbon.

The content of these pigments varies depending on the structure, but is generally used in a range of 0.5 to 20% by weight, preferably 3 to 12% by weight, based on the recording liquid.

On the other hand, in order to obtain a recording liquid with desired physical properties, a water-soluble organic solvent, a pH adjuster, an antifoaming agent, a preservative, etc. can be added.

Examples of water-soluble organic solvents used in combination with water include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, 5ec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Carbon number 1-4
Alkyl alcohols; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin; ethylene glycol Methyl (
or lower alkyl ethers of polyhydric alcohols such as ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazo Examples include lysinone. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferred.

Examples of pH adjusters include various organic amines such as jetanolamine and triethanolamine; inorganic alkaline agents such as alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide; Examples include organic acids and mineral acids.

Polymer dispersants and surfactants used for pigment dispersion can be used as dispersants. Examples of polymer dispersants include proteins such as gelatin, albumin, and casein, natural rubbers such as gum arabic and gum tragacanth, and saponins. Glucosides, cellulose derivatives such as methylcellulose, carboxycellulose, and hydroxymethylcellulose, lignin sulfonates, natural polymers such as shellac, polyacrylates, salts of styrene-acrylic acid copolymers, vinylnaphthalene-acrylic acid copolymers salts of styrene-maleic acid copolymers, salts of vinylnaphthalene-maleic acid copolymers, sodium salts of β-naphthalenesulfonic acid formalin condensates, anionic polymers such as phosphates, polyvinyl alcohol, Polymer dispersants such as nonionic polymers such as polyvinylpyrrolidone and polyethylene glycol, surfactants such as anionic interfaces such as fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, and alkylaryl sulfonates. There are active agents, nonionic surfactants such as polyoxyethine alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters, and one or more of these can be used as appropriate. Can be used selectively. The amount used varies depending on the dispersant, but it is generally desirable to use 1 to 20% by weight based on the total amount of the ink.

On the other hand, the dispersing machine used in the present invention may be any commonly used dispersing machine, and examples thereof include a ball mill, a roll mill, and a sand mill.

Among them, high-speed sand mills are preferred, such as super mills, sand grinders, bead mills, agitator mills, grain mills, guino mills, pearl mills, etc.
Examples include Kobol Mill (all product names).

In the present invention, methods for obtaining pigments having a desired particle size distribution include increasing the specific gravity of the grinding media of the dispersion machine, reducing the size of the grinding media, increasing the filling rate of the grinding media, and Techniques used include lengthening the processing time, slowing down the discharge speed, and classifying the material using a filter or centrifugal separator after pulverization. Alternatively, a combination of these techniques may be used.

〔Example〕

Next, the present invention will be further explained with reference to Examples.

Note that "%" or "%" in the text is based on weight.

Example 1 Carbon black (manufactured by Mitsubishi Kasei, MA-100)
'10 parts styrene-acrylic acid copolymer (
Molecular weight 12000. Acid value 175) 5 parts ethanolamine
2 part urea
8 part glycerin
7 parts ethylene glycol
10 parts pure water
58 parts of the above ingredients were blended and subjected to a dispersion treatment using a Pearl Mill (manufactured by Ashizawa Co., Ltd.) under the following conditions.

Types of grinding media Size of zirconium grinding media
Filling rate of 1.5mm grinding media
65% discharge speed
500m1/min
.

Further, coarse particles were removed by centrifugation treatment (20,000 RPM, 15 minutes) to obtain black ink.

Comparative Example 1 A black ink was obtained in exactly the same manner as in Example 1, except that the centrifugation treatment was omitted from the dispersion treatment.

Example 2 Carbon black (manufactured by Mitsubishi Kasei, MA-100)
10 parts α-methylstyrene-styrene-acrylic acid copolymer (molecular weight 12,500. acid value 197)
6-part aminomethyl propatool
2 part ethylene glycol
10 parts diethylene glycol 5 parts Nitsukol BL-9EX (manufactured by Nikko Chemicals) 0.5 parts pure water
66
．． Blend 5 parts of the above ingredients and use Pearl Mill (Ashizawa Co., Ltd.)
A black ink was obtained by carrying out a dispersion treatment under the following conditions using a commercially available product (manufactured by Kawasaki Co., Ltd.) under the following conditions.

Types of grinding media Size of zirconium grinding media
Filling rate of 1.5mm grinding media
65% discharge speed
100m1/min.

Comparative Example 2 Under the above dispersion conditions, the discharge speed was set to 500 ml/mi.
n.

A black ink was obtained by performing a dispersion treatment.

Example 3 Phthalocyanine blue (Lionol Green G
YK, manufactured by Toyo Ink) 10 parts styrene-maleic acid copolymer (molecular ffl 10000. acid value 200)
8 parts ethanolamine
2 part urea
8 parts polyethylene glycol 10 parts pure water
6
Two parts of the above components were blended, and a dispersion treatment was performed using a Pearl Mill (manufactured by Ashizawa Co., Ltd.) under the following conditions to obtain a blue-green ink.

Types of grinding media Size of zirconium grinding media
Filling rate of 1.5mm grinding media
65% discharge speed
100m1/mi
n.

Comparative Example 3 In the above material composition, the phthalocyanine blue pigment was
acrolex Violet B (made by Bayer)
An ink was obtained in exactly the same manner as in Example 3 except that the following was changed.

Using the recording liquids of Examples 1 to 3 and Comparative Examples 1 to 3 above, an on-demand type multi-head (discharge orifice diameter The following study was carried out using a recording device having a heating resistor of 35 μm, a resistance value of 150 Ω, and a driving voltage of 30 V. In addition, the driving frequency is 2 KH
z and 4 KHz.

Tl: Ejection stability: Continuous ejection was performed in an atmosphere at room temperature, 5° C., and 40° C. for 25 hours and 50 hours, respectively, and the quality of the printed image after the test was visually evaluated.

T2: Foreign matter deposition property: The heating head after the above T1 test was observed under a microscope to check for the presence or absence of foreign matter deposition.

Further, the particle size distribution of the prepared recording liquid was measured using a centrifugal sedimentation type distribution measuring device (manufactured by Shimadzu Corporation).

The evaluation results are shown in Table 1 below. Regarding the evaluations in the table, for T1, ◎ indicates excellent, ◯ indicates good, Δ indicates slightly poor, and × indicates poor. At T2, ◎ indicates that the deposit was not present, ○ indicates that it was slightly observed, △ indicates that half of the heater was covered, and × indicates that the heater was almost covered.

Table 1 Dl・ Volume % of particles with a particle size of 0.6 μm or more D2・
Volume % of particles having a particle size of 0.6 μm or more [Effect] According to the present invention, it is possible to provide a recording liquid that has excellent drive frequency response and can always be ejected stably even when ejected for a long time.
In addition, it is possible to provide a recording liquid with excellent storage stability without clogging the printer.

Patent applicant: Canon Co., Ltd.

Claims (5)

[Claims] (1) A recording liquid made by dispersing pigments in a liquid medium containing water as a main component, characterized in that pigments with a particle size of 0.6 μm or more account for 10% (volume %) or less of the total pigments. recording liquid. (2) The recording liquid according to claim 1, wherein the pigment having a particle size of 0.2 μm or less accounts for 60% or more of the total pigment. (3) A recording method characterized by applying energy to a recording liquid containing a pigment in which 10% or less of the pigment has a particle size of 0.6 μm or more and causing the recording liquid to be ejected as droplets from micropores. (4) The recording method according to claim 3, wherein the recording liquid contains pigments having a particle size of 0.2 μm or less in an amount of 60% or more of the total pigments. (5) The recording method according to claim 3, wherein the energy is thermal energy.