JPH01170674A - Recording liquid - Google Patents

Abstract

PURPOSE:To obtain a recording liquid, having excellent water, light resistance and preservation stability and suitable for ink jet, by dissolving or dispersing an oil-soluble dye and ultraviolet ray absorber, etc., in an oily phase, emulsifying and dispersing the oily phase in an aqueous medium. CONSTITUTION:The aimed recording liquid obtained by dissolving or dispersing an oil-soluble dye (e.g., C.I. Solvent Yellow 1) and an ultraviolet ray absorber (e.g., 2-hydroxy-4-methoxy-5-sulfobenzophenone) and/or an antioxidant (e.g., 2,6-di-tert-butyl-p-cresol), emulsifying and dispersing the resultant oily phase in an aqueous medium. Furthermore, the mode value of particle diameter distribution of emulsified and dispersed particles is preferably) <=10mum.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to recording M (hereinafter referred to as ink) used in various recording instruments such as writing instruments and printers, and particularly relates to recording M (hereinafter referred to as ink) used in various recording instruments such as writing instruments and printers. The present invention relates to an ink suitable for an inkjet recording method in which recording is performed by ejecting ink.

(Prior Art) 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 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. In this case, the characteristics of the ink used are that physical properties such as viscosity and surface tension are within appropriate ranges, 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 that it provides 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, and the recorded image has excellent light resistance, water resistance, and solvent resistance (especially alcohol resistance). (Problem to be solved by the invention) Conventionally, coloring materials for ink in inkjet recording systems have been used because the liquid medium is aqueous. Water-soluble dyes are mainly used, and by using water-soluble dyes, many of the above-mentioned basic requirements of the inkjet recording system are satisfied.

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 source light from 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, water resistance of recorded images often becomes 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, in order to solve the above-mentioned problems of light resistance and water resistance, it is considered to use oil-soluble dyes as pigments. However, oil-based inks using oil-soluble dyes have low surface tension and are unstable in ejection. Furthermore, the ink bleeds significantly and feathering is likely to occur, resulting in extremely poor image quality.

Therefore, an ink in which fine particles of an organic solvent containing an oil-soluble dye are dispersed in an aqueous phase has been proposed (Japanese Patent Laid-Open No. 62-2
07375). However, many commercially available oil-soluble dyes have problems in the mutagenicity test (Ames test), and even those without problems often have insufficient light resistance.

Therefore, the main object of the present invention is to provide an ink that solves the conventional problems as described above, that is, an ink that provides images with good light fastness, water resistance, and quality, and has excellent storage stability as an ink. The goal is to provide the following.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention combines an oil-soluble dye, an ultraviolet absorber, and/or
The recording liquid is characterized in that an oil phase in which an antioxidant is dissolved or dispersed is emulsified and dispersed in an aqueous medium.

(Function) By using an oil-soluble dye as a recording agent component of the ink, the water resistance of the image is improved, and by adding an ultraviolet absorber and/or an antioxidant, the light resistance of the image is improved. An ink with excellent storage stability can be provided by allowing the additives to exist in the form of an emulsion in the ink medium.

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

The ink of the present invention is characterized in that an oil phase in which an oil-soluble dye and an ultraviolet absorber and/or an antioxidant are dissolved or dispersed is emulsified and dispersed in an aqueous medium.

The oil used above is not particularly limited as long as it is substantially insoluble in water, but it is preferable that the vapor pressure is low, as high vapor pressure may cause problems such as the odor of the solvent and the stability of the ink. It happens. Further, it is preferable to have a specific gravity close to that of water, for example, a specific gravity of about 0.8 to 1.2 from the viewpoint of storage stability of the ink.

Preferred oils 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 biphenyls, etc.), esters (e.g., phthalates, benzoates, fatty acid esters,
citric acid ester, phosphate ester, etc.), ethers (
For example, glycol ether, etc.), higher alcohols,
Examples include higher fatty acids, amides, chlorinated paraffins, and silicone oils.

The stiff oil is 1% to 50% by weight of the water phase.
, preferably in the range of 3% to 30%.

The oil-soluble dye to be dissolved or dispersed in the above oily substance is as follows:
For example, the following dyes are preferably used.

C, 1, Solvent Yellow 1.2.3.13.19.
22.29.35.37.38.39.40.43.4
4.45.47.62.63.71,76.81,85
．． 86: C, 1, Solvent Blue 8.27.35.36.37
．． 38.39.40゜58.60.65.67.69.
8], 86.89.91.92.97.99, +00.
109.118.119.122: c, r, solvent blue 14.24.26.34.3
7.38.39.42.43.45.48.52.53
．． 55.59, b7: C, t, solvent black 3.
5.7.8.14.17.19.20.22.24.2
6.27.28.29.43.45, etc., but are not limited to these.

In addition, among various conventionally known water-soluble dyes, dyes made water-insoluble and solvent-soluble by replacing their counter ions (usually sodium, potassium, or ammonium ions) with organic amines can also be used. can.

Preferred examples of the ultraviolet absorber to be dissolved or dispersed in the oil together with the dye include 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2'-dihydroxy-4,4'- Dimethoxy-5-
Sulfobenzophenone Na salt, 2.2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2.4-dihydroxybenzophenone, 2(2'-hydroxy-5-methylphenyl)benzotriazole, Tinuvin 234 (Product name, manufactured by Ciba Geigy)
, 320, 326, 327, 328, Uvin
u1400 (product name, manufactured by BASF), M40, D
49, 490, D50, MS40, N35, N539, (:yasorb LIV9 (product name, American
(manufactured by Cyanamitsu), UV24, UV207, U
V284, UV531, UV1084, UV54
11 etc. are mentioned.

Further, preferable examples of the antioxidant include 2.6-tert-butyl-p-cresol, 2.
6-Lert-butyl-4-ethylphenol, 2(
3)-Butyl-4-oxy-anisole (BHA), 2.6-Lert-butyl-oxytoluene (BH
T), 2,2'-methylenebis(4-methyl-6-tert-
butylphenol), 4,4'-butylidenebis(3-methyl-6=crt
-butylphenol), 4.4'-thiobis(3-methyl-6-tert-butylphenol), 2.2'-thiobis(4-methyl-6-tert-butylphenol), 2.4-dimethyl-6-Lert- Butylphenol, 4-isooctylphenol, hydroquinone, Irganox 245 (trade name, manufactured by Ciba Geigy)
, 259, 565, 1010, 1035FF,
1076, 1081, 1098, 1222, 1330, 1425WL.

Examples include Cyanoxl 790 (trade name, manufactured by American Cyanamid), Cyanoxl 425, Cyanoxl 2246, Cyanoxl 711, Cyanoxl 1212, Cyanoxl LTDP, Cyanoxl MTDP, Cyanoxl 5TDP, etc.

Examples of methods for emulsifying and dispersing the oily substance in which the oil-soluble dye, ultraviolet absorber, and/or antioxidant are dissolved or dispersed in water include methods using ultrasonic waves and methods using various dispersers and stirrs.

At this time, various surfactants that serve as emulsifiers and dispersants may be used as necessary, such as fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, and naphthalene. sulfonic acid formalin condensate,
Anionic surfactants such as polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters,
Examples include nonionic surfactants such as polyoxyethylene alkylamine, glycerin fatty acid ester, and oxyethylene oxypropylene block copolymer. It is used in a range of 5% by weight.

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

The particle size of the emulsified dispersion obtained as described above is preferably such that the mode of the particle size distribution is 10 μm or less, from the viewpoint of storage stability of the ink and nozzle clogging, and the mode of the particle size distribution is preferably 10 μm or less.
If it exceeds 0 μm, the emulsified particles in the ink tend to agglomerate, causing storage stability problems, which is not preferable.

The dye in the emulsified and dispersed particles as described above is generally used in a proportion of about 0.1 to 20% by weight in the total amount of the ink including the ink medium, as in the case of conventional inks,
Further, it is preferable to use the ultraviolet absorber and/or antioxidant in an amount of about 20 to 200 parts by weight per 100 parts by weight of the dye.

A suitable solvent 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. 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, tert-butyl alcohol, and isobutyl alcohol. Alkyl alcohols having 1 to 4 carbon atoms; Amides such as dimethylformamide and dimethylacetamide; Ketone or keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyethylene glycol, polypropylene glycol, etc. Polyalkylene gelicols: ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexandriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. where the alkylene group has 2 to 6 carbon atoms 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 0 to 95% by weight, preferably 10 to 80% by weight, more preferably 20 to 50% by weight based on the total weight of the ink.
% by weight.

In addition to the above-mentioned components, the ink of the present invention may optionally contain:
It may include pH adjusters, viscosity adjusters, surface tension adjusters, 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.
to 20 cps with a surface tension of 30 dyne/cr
It is preferable that the pH value is n or more and has physical properties of about 4 to 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-tip pen, and brush, mechanical recording methods such as a pen plotter and an inkjet method can also be used. Although not limited,
A particularly preferred method is an inkjet method, and the ink of the present invention can be suitably used in any of the various conventionally known inkjet 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, Comparative Examples, and Usage Examples. Note that % in the text is based on weight unless otherwise specified.

Example I C,t, 495 g of solvent red and ultraviolet absorber U
2g of vinu1400 (trade name) and 4g of diethyl phthalate
It was dissolved in 3 g to form an oil phase.

On the other hand, 5 g of polyvinyl alcohol as an emulsifier was dissolved in 195 g of water, the above oil phase was added thereto, and the mixture was heated at 12.000 rpm and 15 ml using a Homomixer made by Tokushu Kika Kogyo.
The ink of the present invention was obtained by emulsifying and dispersing the mixture for 10 minutes.

Example 2 C,1, 495g of Tsurchentread, ultraviolet absorber Cy
asorb UV9 (trade name) 2g and antioxidant Cy
2g of anox1790 (trade name) and 4g of diethyl phthalate
An ink of the present invention was obtained in exactly the same manner as in Example 1, except that the ink was dissolved in 1 g to obtain an oil phase.

Comparative Example I An ink of a comparative example was obtained in exactly the same manner as in Example 1, except that 495 g of Solvent Red C,1 was dissolved in 45 g of diethyl phthalate to obtain an oil phase.

Example 3 C,1, 77g of solvent black and ultraviolet absorber T
inuvin32B (trade name) 3g to 1-methyl-
It was dissolved in 40 g of naphthalene to form an oil phase.

On the other hand, nonionic surfactant NP-7,5 (
(manufactured by Nikko Chemicals), the above oil phase was added thereto, and the output was 20 using an ultrasonic dispersion machine manufactured by Branson.
Emulsification and dispersion was carried out under the conditions of 0W and 10 minutes. 50 g of diethylene glycol was added to this to prepare the ink of the present invention.

Example 4 (1.7 g of Solvent Black 7, 3 g of ultraviolet absorber Tinuxin32F+ (trade name), and 3 g of antioxidant IrganoxlO]0 (trade name) were dissolved in 37 g of 1-methylnaphthalene to form an oil phase. The ink of the present invention was obtained in exactly the same manner as in Example 3.

Comparative Example 2 An ink of a comparative example was obtained in exactly the same manner as in Example 3, except that 7 g of C, t, Solvent Black 7 was dissolved in 43 g of 1-methylnaphthalene to form an oil phase.

Usage example Inkjet recording using the inks of the above examples and comparative examples, each having an on-demand recording head (discharge orifice system 50 μm, piezo vibrator drive voltage 60 V, frequency 4 Hz) that discharges ink using a piezo vibrator. An image is formed by printing on copy paper using a device, and the resulting image is exposed to light for 30 hours using a xenon phase meter (manufactured by Suga Test Instruments), and the light resistance is determined by determining the color difference before and after irradiation. evaluated.

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

In addition, the ink used was heated at 0°C, 20°C, and 60°C, respectively.
After storage for one month, storage stability was evaluated by measuring the occurrence of precipitates and changes in liquid physical properties.

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.

ff=t- Ink Salmon Kotan-1 Aqueous-Image 5-Example 1 0
0 0 Example 2 ◎ ○ O Example 3
0 0 0 Example 4 ◎ ○ ○ Comparative example 1
× o ○ Comparative example 2
OO (Effect) According to the present invention as described above, by using an oil-soluble dye as an ink recording agent, the water resistance of an image is improved, and by adding an ultraviolet absorber and/or an antioxidant, the image is improved. An ink with improved light resistance and excellent storage stability was provided by making the dye and additives present in the ink medium as an emulsion.

Claims (3)

[Claims] (1) A recording liquid characterized in that an oil phase in which an oil-soluble dye and an ultraviolet absorber and/or an antioxidant are dissolved or dispersed is emulsified and dispersed in an aqueous medium. (2) The recording liquid according to claim (1), wherein the mode of the particle size distribution of the emulsified dispersed particles is 10 μm or less. (3) Claim No. (1) for inkjet use
Recording liquid described in section.