JPH01193376A - Recording liquid and method for recording using said liquid - Google Patents

Abstract

PURPOSE:To obtain a recording liquid, capable of providing an image excellent in water and light resistance without causing sediments on a thermogenic head of an ink jet device, by emulsifying or dispersing an oily phase in a coloring matter-containing aqueous medium and regulating the content of a bi- or polyvalent metal. CONSTITUTION:A recording liquid obtained by emulsifying or dispersing an oily phase (preferably silicone oil, etc.) in an aqueous medium (preferably a mixed solvent of water and a water-soluble organic solvent, such as diethylene glycol) containing a coloring matter (preferably acid or direct dye and regulating the total content of bi- or polyvalent metal to <=300ppm. The above-mentioned recording liquid is prepared by, e.g., emulsifying or dispersing an oily phase in an aqueous medium containing a dye after removing the bi- or polyvalent metal by an ion exchange method, etc., using ultrasonic waves, etc. Furthermore, an ultraviolet ray absorber or antioxidant or both are preferably contained in the oily phase to further improve light resistance of the resultant image.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a recording liquid (hereinafter referred to as ink) used for writing and various recording devices such as printers, and a recording method using the ink. The present invention relates to an ink suitable for an ink jet recording method in which recording is performed by ejecting droplets from an orifice of a recording head, and a recording method using the ink.

More specifically, the water resistance and light resistance of recorded images are improved, the long-term storage stability of 1L ink is excellent, there is no clogging of writing instruments or the tip of the ejection orifice, and there is no possibility of clogging, especially when thermal energy is applied. The present invention relates to an ink that does not produce sediment in a heat-generating head of an ink sheet device that ejects the ink, and a recording method using the ink.

(Prior Art) Conventionally, the inkjet recording method has the advantage that it generates little noise during recording, is easily compatible with color printing, and can obtain high-resolution recorded images at high speed.

In the ink sheet recording method, inks prepared by dissolving various water-soluble dyes in water or a mixture of water and a printing press solvent are used. In this case, the characteristics of the ink used must be that the physical properties such as viscosity and surface tension are within an appropriate range, that the dissolved components have high dissolution stability, that they do not clog the fine orifices, and that they have a sufficiently high concentration. It is required to provide a recorded image and that no change in physical properties or precipitation of solids occurs during storage.

In addition to the above characteristics, recording can be performed without being restricted by the type of recording material, the fixing speed is high, the recorded image has excellent light resistance, water resistance, and solvent resistance, and it has excellent resolution. Properties such as providing a recorded image are also required.

Furthermore, an ink sheet system that uses thermal energy to eject ink is required to have an inkjet system that does not generate deposits on the heat generating head.

(Problem to be solved by the invention) Conventionally, since the liquid medium is water-based, water-soluble dyes have been mainly used as coloring materials for ink in inkjet recording methods. Many of the above basic requirements of the recording system are met.

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. In other words, if the recorded image is exposed to sunlight,
When exposed to light from a light source such as a fluorescent lamp or a projector, recorded images may disappear, become difficult to read, or fade during long-term storage.

Furthermore, since the dye is water-soluble, the water resistance of the recorded image is often a problem. That is, if a recorded image is exposed to rain, sweat, or water from drinking or drinking, the recorded image may blur or disappear.

Therefore, it is known to add existing ultraviolet absorbers and antioxidants to ink for the purpose of improving the light resistance of water-soluble dyes.

However, many of these UV absorbers are insoluble in the ink medium, and even those that are slightly soluble can precipitate and aggregate in the ink, causing clogging at the orifice tip and pen tip. It has become.

Therefore, the main purpose of the present invention is to provide an ink that solves the problems of conventional inks as described above, that is, to provide an image with good light fastness and water fastness, and to have good storage stability as an ink. In addition, it is an object of the present invention to provide an ink that does not cause clogging at the pen tip or the tip of the orifice, and does not cause deposits on the heat generating head, and a recording method using the ink (one step to solve the problem). ``--The first objective is achieved by the present invention as described below.

That is, the present invention provides an ink in which an oil phase is emulsified and dispersed in an aqueous medium containing at least a pigment, and the total content of divalent metals in the ink is adjusted to 30 ppm or less. A second invention is a recording method in which recording is performed on a recording material by ejecting ink from a fine aperture, characterized in that the ink is the ink or the ink described above. It is.

(Function) The storage stability of the ink is improved by emulsifying and dispersing the oil phase in the ink containing the pigment, and by suppressing the total content of -6 of divalent and higher metals in the ink to 30 ppm or less. 1. The clogging property and the occurrence of deposits in the heat generating head P have been improved.
Images formed using Tsukowa also have improved water resistance because the above-mentioned oil acts as a water repellent.

In a preferred embodiment, an ultraviolet acid absorber and/or an antioxidant may be contained in the oil phase, thereby making it possible to provide images with excellent light resistance.

In other words, commercially available dyes contain many impurities other than dyes (
For example, various organic and inorganic substances such as dispersants, leveling agents, etc. are contained, and these impurities may clog the orifice of the inksheet device, form deposits on the surface of the heating head, or cause problems during long-term storage. This may cause precipitation to occur. Among these impurities, the concentration of divalent or higher-valent metals is particularly closely related, and an ink in which the concentration of such impurities is controlled has been proposed (Japanese Patent Laid-Open No. 11367/1983).
Publication No. 1).

However, the above proposal is applied to a water-soluble homogeneous ink, and the ink according to the present invention is an oil-in-water emulsion (hereinafter referred to as emulsion ink), so the above proposal cannot be applied as is. It is something.

As a result of intensive research, the present inventor has found that, in the case of emulsion ink, metals of divalent or higher valence, especially 1llj lead,
If the concentration of aluminum and/or magnesium is high,
In addition, the long-term storage stability of the ink may deteriorate significantly, and in addition, the ejection orifice filled with ink and the capillary opening of the pen tip may become severely clogged, and in ink jet devices that use thermal energy, deposits may form on the heat generating head. The present invention was developed based on the knowledge that this phenomenon occurs.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

As for the dyes used in the present invention, most of the dyes listed in the Color Index can be used, and even those not listed in the Color Index are often suitable. In particular, those used numerically include water-soluble acid dyes, direct dyes, basic dyes, reactive dyes, etc. Other disperse dyes (including reactive disperse dyes) can also be used. Particularly preferred are acid dyes and direct dyes.

It is preferable to use the stiff dye at a concentration of 5% by weight or less in the emulsion ink.If the concentration exceeds this, in the case of emulsion ink, oil droplets may aggregate, dye precipitation may occur, and the ink may deteriorate. This is undesirable because it reduces storage stability and tends to cause clogging at the tip of the pen or orifice.

Methods for controlling the content of divalent or higher metals in the present invention include salting out method, ion exchange method, crystallization method in which dye is precipitated by adding an organic solvent miscible with the aqueous dye solution, solvent extraction method, Any conventionally known method can be used, such as a coagulation-precipitation method in which impurities are precipitated by adding a coagulant, or a combination thereof.

In the present invention, it is necessary to use these methods to reduce the total content of divalent or higher metals in the dye to 30 ppm or less in the ink, more preferably 20 ppm or less, and more preferably 20 ppm or less. shall be 15 ppm or less. These contents can be measured by known methods such as atomic absorption spectrometry and stimulated plasma emission spectroscopy.

The ink of the present invention is characterized in that an oil phase is emulsified and dispersed in the ink which contains the above dye and has a total content of 4T of divalent or higher metals of 30 ppm or less.

The oil phase used above is not particularly limited as long as it is substantially insoluble in water, but it is preferable to have a low vapor pressure.If the vapor pressure is high, oil odor and ink stability may be a problem. It becomes. Also, the specific gravity is close to that of water, for example,
A specific gravity of about 0.8 to 1.2 is preferable from the viewpoint of storage stability of the ink.

Preferred oil phases include, for example, vegetable oils (e.g., olive oil, soybean oil, castor oil, etc.), mineral oils (e.g.,
petroleum, Kesilon, paraffin, etc.), hydrocarbons (e.g., alkyl-substituted benzene, alkyl-substituted naphthalene, alkyl-substituted biphenyl, etc.), esters (e.g., phthalate esters, benzene esters, fatty acid esters, citric acid esters, phosphoric acid) esters, etc.), ethers (eg, glycol ethers, etc.), higher alcohols, higher fatty acids, amides, chlorinated paraffins, silicone oils, and the like.

These oil phases are used in a weight ratio of 1% to 50%, preferably 3% to 30%, relative to the aqueous phase which is the ink medium.

Examples of methods for emulsifying and dispersing the above-mentioned oil phase in an aqueous medium containing a dye include a method using ultrasonic waves and a method using various dispersers and stirrs. At this time, surfactants that serve as various emulsifiers and dispersants, such as fatty acid salts,
Anionic surfactants such as alkyl sulfate salts, alkyl hanzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate ester salts, etc. , polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene oxypropylene block copolymer, and other nonions. These emulsifiers are used in an amount of 0.501 to 201 TjLi%, preferably 0.1 to 5%, based on the aqueous phase.

Furthermore, in addition to or in place of the above-mentioned surfactants, polymeric substances such as PVA, PVP, arahia gum, etc. can also be used as protective colloids.

The particle size of the emulsified dispersion obtained as described above is determined to be 1 particle size 4i from the viewpoint of ink storage stability and orifice clogging.
It is preferable that the mode is 10 μm or less, and if the mode exceeds 10 μm, the emulsified particles in the ink tend to aggregate, which is not preferable because storage stability becomes a problem.

In addition to the above method, it is also within the scope of the present invention to emulsify and disperse the oil phase in an aqueous medium and then add a dye from which divalent or higher-valent metals have been removed.

Also, preferred embodiments of the present invention j, l,! ! In the third embodiment, the light resistance of the formed image can be further improved by including an ultraviolet absorber and/or an antioxidant+h agent in the oil phase.

Preferred examples of the ultraviolet absorber to be dissolved or dispersed in the oil phase include 2-hydroxy-4-methoxy-5-sulfohensiphenone, 2,2'-dihydroxy-4,4'-dimethoxy-5 −
Sulfohensephenone Na salt, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2(2'-hydroxy-5-methylphenyl)hensitriazole , Tinuvin 234 (product name, manufactured by Ciba Geigy)
, 320, 326, 327, 328.11vi
NU1400 (product name, BASF), M40, D49, 490, D50, MS40, N35,
Same N539, Cyasorb IIV9 (product name, manufactured by American Cyanamid), same UV24, same UV207, same UV
284, UV531, 11V1084, UV54
11 etc. are mentioned.

Further, preferable examples of antioxidants include 2.6-diL-butyl-p-cresol, 2.
．． 6-tart-butyl-4-ethylphenol, 2(
3)-Butyl-4-oxy-anisole (BHA), 2,6-jer L-butyl-oxytoluene (BHA)
)(T), 2,2'-methylenebis(4-methyl-6-tert-
butylphenol), 4,4'-butylidenebis(3-methyl-6-ter
L-butylphenol), 4.4'-thiobis(3-methyl-6-terL-butylphenol), 2.2'-thiobis(4-methyl-6-terL-butylphenol), 2.4-dimethyl-6-t , ert-butylpheno-4
-Inoctylphenol, Hydroquinone, Irganox 245 (trade name, manufactured by Ciba Geigy)
, 259, 565, 1010, 1035FF,
1076, 1081, 1098, 1222, 1330, 1425WL.

Cyanoxl 790 (product name, American Cyanamid! U), Cyanoxl 425, Cyanoxl 2246, Cyanoxl 711,
Examples include 1212, LTDP, MTDP, and 5TDP.

The above-mentioned ultraviolet absorbers and/or antioxidants are added in an amount of 1 to 50% by weight, preferably 10% by weight, based on the oil phase.
Dissolved or dispersed in an amount of 30% to 30% by weight.

The aqueous medium suitable for use in the ink of the present invention is water or a mixed solvent of water and a water-soluble organic solvent, and particularly preferred is a mixed solvent of water and a water-soluble organic solvent, which is water-soluble. The ink contains polyhydric alcohol, which has the effect of preventing ink from drying, as an organic solvent. Furthermore, as water, it is preferable to use ionized water rather than ordinary water containing various ions.

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, tart-butyl alcohol, and isobutyl alcohol. Alkyl alcohols having 1 to 4 carbon atoms Amides such as dimethylformamide and dimethylacetamide; Ketones or keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylenes such as polyethylene glycol and polypropylene glycol Gelicols; alkylene groups having 2 to 6 carbon atoms such as ethylene glycol, propylene glycol, butylene gellicol, triethylene glycol, 1,2,6-hexandriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols containing: Glycerin: Lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; N-methyl-2 -pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and the like. 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.

The content of the water-soluble organic solvent in the ink is generally from 0 to 95+W7=(% by weight) based on the total weight of the ink.
, preferably 10 to 80% by weight, more preferably 20% by weight
It ranges from 50% by weight.

In addition to the above-mentioned components, the ink of the present invention may optionally contain:
pH; J! It may include I conditioners, viscosity modifiers, surface tension modifiers, and the like.

The pH adjuster used in the above ink is as follows:
Examples 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, organic acids, and mineral acids.

The ink of the present invention as described above has a viscosity of 1 at 25°C.
With a fi of 20 cps, the surface tension is 30 dyne/cm
In the above, it is preferable that the material has physical properties of about pHIJl to about 10.

As a recording method using the above ink of the present invention, in addition to so-called general writing instruments such as a general pen, fountain pen, felt pen, and brush, mechanical recording methods such as a pen plotter and an inkjet method can also be used. Although not limited to,
A particularly preferred method is an inksheet method, and the ink of the present invention can be suitably used in any of the conventionally known inksheet methods.

In addition, the recording materials used include general paper, coated paper, synthetic paper,
Any of various plastic films can be used and is not particularly limited.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. Note that % in the text is based on weight 1 standard.

Example 1 Sodium sulfate was added to a 10% aqueous solution of Dye C, 1 and Food Black 2 to salt out the dye, and the precipitate was washed with a saturated aqueous solution of sodium sulfate and then dried. This was extracted with methyl cellosolve and the solvent was distilled off to obtain a dye powder. 5% of this
The aqueous solution was treated with chelate resin DOWEX A-1 (manufactured by Dow Chemical) and evaporated to dryness to obtain a dye powder.

15g of the above powder and surfactant Niracol BT-+2 ("
] 3 g of photochemicals lu) were dissolved in 282 g of water.

100 g of 2-methylnaphthalene was added to the aqueous solution and emulsified and dispersed using an ultrasonic disperser manufactured by Branson at 250 W for 10 minutes. To this, diethylene glycol 10
0 g was added and stirred to obtain the ink of the present invention.

Comparative Example 1-1 An ink of a comparative example was obtained in the same manner as in Example 1 except that the dye purification step in Example 1 was omitted.

Comparative Example 1-2 3 g of a dye purified in the same manner as in Example 1 was dissolved in 77 g of water, and 20 g of diethylene glycol was added and stirred to obtain an ink of a comparative example.

Example 2 Isopropyl alcohol was mixed with a 10% aqueous solution of Dye C,1 and Acid Blue 9 to precipitate 70% of the dye. This was collected by filtration, a 5% aqueous solution was prepared again, and the solution was passed through a column filled with chelate resin Amberlite IRc-718 (manufactured by Organo) and evaporated to dryness to obtain a dye powder. UV absorber 2-hydroxy-4-methoxybenzophenone 1
2 g of the antioxidant 2.6-tert-butyl-cresol (8 g) were dissolved in 80 g of tributyl phosphate.

16g of the above dye and the surfactant Niracol TO-10M (
(manufactured by Nikko Chemicals) was dissolved in 200 g of water, and the above oil phase was added thereto, followed by emulsification and dispersion using a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd. at 8,000 rpm for 30 minutes. Furthermore, add 80g of triethylene glycol,
The ink of the present invention was prepared by stirring.

Comparative Example 2-1 An ink of a comparative example was obtained in exactly the same manner as in Example 2, except that the dye purification step was omitted.

Comparative Example 2-2 4 g of a dye purified in the same manner as in Example 2 was dissolved in 76 g of water, and 20 g of triethylene glycol was added and stirred to obtain an ink of a comparative example.

Example 3 Inorganic salts were removed from an aqueous solution of Dye C,1 and Acid Red 37 using a reverse osmosis device (manufactured by Toshi), and 10% of a 20% suspension of aluminum hydroxide was added to 1 liter of a 5% aqueous solution of this.
After adding 0 g and stirring for 1 hour, the mixture was centrifuged to obtain a supernatant. Stiffness chelate resin CR-10 (manufactured by Mitsubishi Chemical Corporation)
The dye powder was obtained by passing through a column packed with and evaporating to dryness.

Ultraviolet absorber Tinuvin 328 (product name) 20
g was dissolved in 80 g of propyl benzoate.

25g of the above dye, surfactant and Niracol MYS-IQ
(Product name) 10g in 285g of water, add Moeki oil phase, and use a Branson ultrasonic dispersion machine to dissolve 200g of
Emulsification and dispersion was carried out under conditions of W15 minutes and 1zM. 50 g of glycerin and 30 g of ethylene glycol were added to this and stirred to obtain the ink of the present invention.

Comparative Example 3-1 An ink of a comparative example was obtained in exactly the same manner as in Example 3, except that the dye purification step was omitted.

Comparative Example 3-2 An ink of a comparative example was obtained in exactly the same manner as in Example 3 except that the chelate resin treatment was omitted in the dye purification step of Example 3.

Comparative Example 3-3 5 g of the dye purified by the same company as in Actual hh Example 3 was dissolved in 79 g of water, and further 10 g of glycerin and 6 g of ethylene glycol were added.
was added and stirred to obtain an ink of a comparative example.

Example 4 Using the inks of Example and Comparative Example, heat energy was applied to the ink in the recording head to generate droplets,
An image is formed by printing on copy paper using an inkjet recording device having an on-demand type multi-head for recording (discharge orifice diameter 35 μm, heating resistor resistance value 150 ohms, drive voltage 30 V, frequency 2: 117 mm). The obtained image was irradiated with light for 30 hours using a xenon fade meter (manufactured by Suga Test Instruments), and the light resistance was evaluated by determining the color difference between 1n and after irradiation.

Further, water resistance was evaluated by dropping water droplets on the obtained image and visually judging the degree of blurring of the image.

Further, the above inks were sealed in glass bottles and stored at 0°C, room temperature, and 60°C for 3 months, and then the formation of precipitates and changes in liquid physical properties were observed.

Also, each ink was filled into the recording device and heated at 60°C for 1 hour.
The discharge after being left for several months was examined to evaluate the clogging property.

Also, each ink was filled into the recording device and heated at room temperature for 4 hours.
Continuous ejection was carried out for 8 hours, and the degree of deterioration of the image quality after the test was checked, the surface of the heating head was observed under a microscope, and the ifjj% of deposits was checked to evaluate the ejection stability.

Furthermore, each ink was analyzed using an induced plasma emission spectrometer to analyze zinc, aluminum, magnesium, calcium,
Concentrations of iron, silicon and manganese were measured.

The evaluation results are shown in Table 1 below. ◎ in the table indicates excellent quality, O
indicates good quality, △ indicates slightly poor quality, and × indicates poor quality.

γ! ; 1? +-'= Example 1 00000 24 17 Comparative example! -1
00x x X 41 33 Comparative Example 1-2
Q x Q ○ 0 2417 Example 2
◎ 00001913 Comparative Example 2-1 ◎ ○ × △ x 37
:12 Comparative Example 2-2 X X OO○ 191
3”JJi Example 3 @OOOO2719 Comparative Example 3
-1 ◎ O× △ x 52 : 13 Comparative Example 3-2 ◎ O△ △ x : I5 3I Comparative Example 3-3 △ I
Total of zinc, aluminum and magnesium
Unit: ppm (Effect) According to the present invention as described above, since the ink of the present invention is an ink in which an oil phase is emulsified and dispersed in an aqueous phase containing a dye, the oil acts as a water repellent, so that images are The water resistance of
Since ultraviolet absorbers and/or antioxidants can be added to the oil phase, the light resistance of images is also improved, and by controlling the concentration of divalent or higher metals in the ink, the long-term shelf life of the ink can be improved. This ink is excellent in clogging at the ejection orifice and ejection stability in a heat-generating head that ejects ink by applying thermal energy, making it an extremely suitable ink for inkjet applications.

Patent applicant: Canon Co., Ltd.

Claims (7)

[Claims] (1) A recording liquid in which an oil phase is emulsified and dispersed in an aqueous medium containing at least a dye, and the total content of divalent or higher metals in the recording liquid is adjusted to 30 ppm or less. Characteristic recording liquid. (2) In a recording method in which recording is performed on a recording material by discharging a recording liquid from a fine orifice, the recording liquid is
A recording method characterized by using the recording liquid according to item 1). (3) Claims (1) and (2) in which the divalent or higher-valent metal is zinc, aluminum, and/or magnesium.
The recording liquid and recording method described in section 2). (4) The recording liquid and recording method according to claims (1) and (2), wherein the pigment is a water-soluble dye or a disperse dye. (5) The recording liquid and recording method according to claims (1) and (2), wherein the oil phase contains an ultraviolet absorber and/or an antioxidant. (6) The recording liquid and recording method according to claims (1) and (2), wherein the dye has a concentration of 5% by weight or less in the recording liquid. (7) The recording method according to claim (2), wherein the recording method is an inkjet method performed by applying thermal energy.