JPS62199665A - Formation of color image - Google Patents

Abstract

PURPOSE:To improve recording characteristic, extrusion and preservation stability, etc., by using an aqueous ink employing respective specific dyes in yellow, magenta, cyan and black inks for forming color images by an ink jet method. CONSTITUTION:Color images are formed by using an aqueous ink employing (A) a dye expressed by formula I (R is H, lower alkyl, etc.; X is acetyl, etc.; M is alkali metal, ammonium, et.; l is 0-2; m and n are 0 or 1) in magenta ink, (B) a dye expressed by formula II (Q is -NHCONH- or bond expressed by formula III; X1 and X2 are H or phenyl substituted by -SO3M, etc.; R is methyl, etc.) in yellow ink, (C) a dye expressed by formula IV (m is 1-4; n is 0-3) in cyan ink and (D) a dye expressed by formula V or VI (R1 is H or phenyl substituted by -SO3M, etc.; R3 is H or a group expressed by formula VII; R3 and R4 are H, lower alkyl, etc.; n is 0 or 1) in black ink by an ink jet method.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for forming a color image, and more particularly, to a method for forming a color image using a combination of yellow, magenta, cyan, and black aqueous inks. In particular, the present invention relates to a method of forming a color image using an inkjet method, in which droplets are ejected from an orifice of a recording head to form a color image on a recording material such as paper or resin film.

(Prior Art) The inkjet method includes various ink ejection methods (for example, an electrostatic suction method, a method of applying mechanical vibration or displacement to the ink using a piezoelectric element, a method of heating the ink to foam it,
By using a method that uses the pressure at that time, etc.), the ink can be
(droplets) are formed and some or all of them are attached to a recording material such as paper to perform recording.

In this method, it is possible to form a color image by using a plurality of nozzles and using inks of a plurality of different hues in which various dyes are dissolved in water or organic solvents. The ink used in such an inkjet method is required to have the following performance.

(1) Good recording can be performed on recording paper of high versatility and high size as a recording material.

(2) To provide images with excellent water resistance, light resistance, abrasion resistance, etc.

(3) Excellent resolution or color tone reproducibility in color imaging.

(4) It has high dissolution stability or storage stability in liquid medium components, and is unlikely to cause clogging of the discharge orifice.

(5) Providing an image with high optical density and clear one color tone.

(6) In addition to (1) to (5), especially in inkjet systems that utilize thermal energy, thermal stability is desired.

However, a method of forming a color image using an ink that satisfies all of these characteristics (1) to (8) has not been known so far. In particular, in the inkjet method that uses thermal energy, thermal energy is directly applied to the ink, and the temperature at the bubble generating area is instantaneously 250 degrees Celsius.
In order to reach temperatures exceeding Additional characteristics such as no deposits are required. Therefore, although inkjet method inventions that satisfy (1) to (5) have been disclosed in Japanese Patent Laid-Open No. 59-96967, etc., the method (6) is not fully satisfied.

Therefore, an object of the present invention is to provide an inkjet jet system that fully satisfies the requirements (5) above, has sufficient suitability for the inkjet system according to the system (8), and is capable of producing fully satisfactory color images. The purpose is to provide a method.

The present inventors conducted intensive research to achieve the above object and found that the properties (1) to (6) required of the ink are greatly influenced by the properties of the water-soluble dye contained in the ink. I found out something.

Therefore, the present inventors continued their research on dyes, and found that the combination of dyes in a specific group of dyes mentioned above (1) to (8)
) The inventors have discovered that this is a dye suitable for color image forming methods that satisfies all the characteristics, leading to the present invention.

(Disclosure of the Invention) That is, the present invention provides a method for forming a color image by an inkjet method using yellow, magenta, cyan, and black aqueous inks, wherein the dye of the magenta ink is represented by the following general formula (I). The yellow ink contains one or more dyes represented by the general formula (U) below, and the cyan ink contains one or more dyes represented by the general formula (m) below. A method for forming a color image is characterized in that the black ink contains at least one dye represented by the following general formula (JT) or (V) as the dye of the black ink.

(However, in the above formula, R represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a lower acylamino group, a nitro group, or a halogen atom, and X represents an acetyl group, a benzoyl group, a paratoluenesulfonyl group, a 4-chloro- 6-
It represents any of the hydroxy-1,3゜5-triazin-2-yl groups, M represents an alkali metal, ammonium or organic amines, and the letters are 0 to 2. (m or n represents 0 or l) (However, in the above formula, Q represents -NHCONI (- or a hydrogen atom, -5O3N, -COON or a phenyl group and a naphthyl group substituted with a hydroxyl group, and R is a methyl or methoxy group, n represents 0 or 1, M represents an alkali metal, ammonium or organic amines) (However, in the above formula, M represents an alkali metal, ammonium or organic amines, m is 1 to 4, n is O
~3. ) S03) f (However, in the above formula (IT) or (V), R1 represents a hydrogen atom, a -503M group or a phenyl group substituted with -GOON, and R2 represents a hydrogen atom or
R3 and R4 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower acylamino group, M represents an alkali metal, ammonium or an organic amine, and n is 0 or 'l. ) Next, to explain the present invention in more detail, the dye of the water-based ink in the inkjet system, particularly the inkgeniet system that uses thermal energy, has the characteristics of the water-based ink required in the general inkjet system, that is, the above-mentioned properties. Of course, properties (1) to (5) are required, but in addition, the dye of the water-based ink is required to have high thermal stability, and furthermore, it is necessary to utilize these thermal energies. The inkjet method uses four colors (i.e. yellow, magenta, cyan,
All dyes of these four colors are required to have the same level of properties (1) to (5) above, especially high thermal stability. Although it was extremely difficult to find a combination of dyes of four colors, the inventor's detailed research revealed that the most excellent color image formation by inkjet method can be achieved by combining a group of specific dyes as described below. has been realized.

The dyes represented by the above general formulas (I) to (V) that are used in the present invention and mainly characterize the present invention include any dye as long as it is included in the above general formulas (1) to (V). However, particularly preferred specific examples include the following. Further, although the sulfonic acid group and the carboxyl group are shown as alkali metal salts, it goes without saying that other ammonium salts, amine salts, etc. may also be used.

The water-based ink used in the present invention has the general formula (I
) to (V) are used to prepare water-based inks of four colors, yellow, magenta, cyan, and black, respectively, but the methods for preparing water-based inks of these colors are all based on prior art. It is good to follow. In addition, the water-based inks of each color used in the present invention must contain one kind of dye of the general formulas (1) to (V) or a plurality of dyes of the same color, as well as the color tone of each water-based ink. Other dyes not included in general formulas (I) to (V) may also be included to adjust the color.

The content of each of the above-mentioned specific dyes in the ink is determined depending on the type of liquid medium component, the characteristics required of the ink, etc., but generally it is 1% by weight based on the total weight of the ink. 1-20%, preferably 0.5
The content ranges from 1 to 15%, more preferably from 1 to 10%. Of course, these dyes can be used alone or in combination of two or more, or in combination with various dyes such as other direct dyes and acid dyes with the dye as an essential component.

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, which is a water-soluble organic solvent. It contains polyhydric alcohol, which has the effect of preventing ink from drying, as a solvent. In addition, as water, it is preferable to use deionized water rather than ordinary water containing various ions.As for the water-soluble organic solvent used in combination with water, for example, methyl alcohol, ethyl alcohol, etc. , C1-4 alkyl alcohols such as n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tart-butyl alcohol, isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; acetone, dimethylalcohol; Ketones or keto alcohols such as acetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, trie-thiodiglycol, 1°2.6 - Alkylene glycols in which the fullkylene group contains 2 to 6 carbon atoms, such as hexandriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin: ethylene glycol methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether , lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethylni-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 in the range of 5 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. be.

The water content at this time is determined within a wide range depending on the type of the solvent component, its composition, and the desired characteristics of the ink, but it is generally 10 to 90% of the total weight of the ink.
Preferably 10-70%, more preferably 20-70%
is considered to be within the range that occupies

The ink of the present invention, which is formulated from such components, has excellent recording properties (signal response, stability of droplet formation, ejection stability, long-term continuous recording, ejection after a long recording pause). Stability) Storage stability, fixing properties to recording materials, light resistance, weather resistance, water resistance, etc. of recorded images are all well-balanced and excellent. In order to further improve such properties, various conventionally known additives may be added.

For example, viscosity modifiers such as polyvinyl alcohol, celluloses, and water-soluble resins; various cationic, anionic, or nonionic surfactants; surface tension modifiers such as jetanolamine and triethanolamine; pH modifiers using buffer solutions; Antifungal agents and the like can be mentioned.

Further, in order to prepare ink used in an inkjet system that charges the ink, a resistivity adjuster such as inorganic salts such as lithium chloride, ammonium chloride, and sodium chloride is added.

Note that when applied to an inkjet system in which ink is ejected by the action of thermal energy, thermal physical property values (eg, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted.

The present invention uses the above-mentioned four-color inks to form a color image by an inkjet method.As the inkjet method, any conventionally known method can be used, and a particularly preferred method is a thermal method. This is a method that uses energy.

The inkjet method may be any method as long as it can effectively remove the ink from the nozzle and apply the ink to the recording material, which is a projectile. Typical examples of these methods include, for example: IEEE Trans actions on Industry Applications
Industry Applications)V
ol, JA-13, No. 1 (February/March 1977 issue), Nikkei Electronics April 19, 1978 issue,
It is described in the January 29, 1873 issue and the May 8, 1974 issue. The methods described above are suitable for the present invention, and to explain some of them, there is an electrostatic suction method.
11 A strong electric field is applied between the ink and the accelerating electrode placed in front, and the ink is turned into particles and drawn out one after another from the nozzle, and while the drawn ink flies between the deflection electrodes, information signals are given to the deflection electrodes and recorded. There are two methods: a method in which ink particles are ejected in response to an information signal without deflecting the ink particles, and both are effective for the present invention.

The second method is to forcibly eject minute ink particles by applying high pressure to the ink with a small pump and mechanically vibrating the nozzle with a crystal oscillator. At the same time as the injection, it is charged according to the information signal. When the charged ink particles pass between the deflection electrode plates, they are deflected according to the amount of charge. Another method using this method is called the microdot inkjet method. In this method, ink pressure and excitation conditions are kept within a certain range of appropriate values, and two types of ink droplets, large and small, are ejected from the nozzle tip. Only small and medium-sized droplets are generated and used for recording. The feature of this method is that it is possible to obtain a group of minute droplets even with a nozzle diameter that is larger than conventional methods.

A third method is a piezo element method, in which a piezo element is used as a pressure means for applying pressure to the ink, rather than a mechanical means such as a pump as in other methods. A method of applying pressure to the ink and ejecting it from a nozzle by applying an electric signal to a piezo element to cause mechanical displacement.
Particularly suitable is a method such as that described in Japanese Patent No. 7, in which ink subjected to the action of thermal energy undergoes a sudden change in volume, and the acting force resulting from this state change causes the ink to be ejected from a nozzle.

Recording materials that can be used in the method of the present invention include various inkjet recording papers and O
Of course, excellent records can be made using plastic sheets for HP, and other widely used office paper such as copy paper, report paper, pound paper, slip paper, continuous slip paper, and computer stamping paper etc. can be used, and these papers may be low-size paper or high-size paper.

According to the present invention as described above, the 4
The dyes used in the color water-based inks are all at the same level and have excellent dissolution stability and storage stability in liquid media, making them suitable as water-based inks for general inkjet printing. In particular, all dyes have excellent thermal stability against thermal energy, so even in inkjet systems that use thermal energy, they have excellent ejection stability without the generation of precipitates or changes in the color tone of the dye. It is possible to maintain ejection responsiveness and the like. Since the dyes of the aqueous inks of any color have excellent light fastness, water resistance, sharpness, etc., it is possible to provide color images of excellent quality.

Some water-based inks used in conventional inkjet systems are known to have excellent inkjet suitability for any of the colors, but they do not have the same level of suitability for all four colors: yellow, magenta, cyan, and black. Since water-based inks with various suitability were not known, it was not possible to provide excellent color images, especially in inkjet systems that use thermal energy.However, in the present invention, a specific group of dyes By selecting and combining four color aqueous inks, it has been possible to provide color images of superior quality to a degree that cannot be provided by conventional techniques.

Next, the present invention will be explained in more detail by referring to Reference Examples, Examples, and Comparative Examples. In the text, parts or % are based on weight unless otherwise specified.

Reference Example 1 Yellow, magenta, cyan, and black aqueous inks used in Example 1 were prepared by mixing the following components and then filtering under pressure using a Teflon filter having an average pore size of 0.45 gm.

Magentan 1 Exemplary dye M-13 parts Water 6
0 parts diethylene glycol 30 parts glycerin 7 parts yellow ink 1 Exemplary dye Y-12, 5 parts water 7
o part diethylene glycol 20 parts N-methylpyrrolidone 7.5 parts cyan ink 1 exemplified dye Cy-14 parts water 6
0 parts ethylene glycol 10 parts Polyethylene glycol@300 20 parts N-methylpyrrolidone 10 parts Blur-in 1 Exemplary dye Bk - 13 parts Exemplary dye Bk - 32 parts Water 60 parts Diethylene glycol 30 parts N-methylpyrrolidone 10 parts Mazene Ink 2 Exemplary dye M-23 parts Water 60 parts Diethylene glycol 30 parts Glycerin 7 parts Yellow ink 2 Exemplary dye Y-22, 5 parts Water 70
1 part diethylene glycol 20 parts N-methylpyrrolidone 7.5 parts cyan ink 2 parts exemplified dye cy-z 4 parts water
60 parts ethylene glycol 10 parts polyethylene glycol 1300 20 parts N-methylpyrrolidone
10 parts Bra Quink 2 Exemplary Dye Bk - 23 parts Exemplary Dye Bk - 42 parts Water 60
Part Diethylene Glycol 30 Parts N-Methylpyrrolidone 10 Parts Reference Example 2 In the same manner as in Reference Example 1, each of four color aqueous inks of yellow, magenta, cyan and black to be used in a comparative example having the following composition was prepared.

Magenta Ink Edible Red No. 104 (Phloxine, Acid Red-92
, manufactured by Daiwa Kasei) 3 parts water
60 parts diethylene glycol 30 parts glycerin
7-part engineering" Lji: Niro Otsu 1 Food Yellow No. 4 (Tartrazine, Acid Yellow 23,
Daiwa Kasei) 3 parts water
70 parts diethylene glycol 20 parts N-methylpyrrolidone
7.5 parts cyan ink Edible Blue No. 1 (Brilliant Blue, Acid Blue 9,
Daiwa Kasei) 3 parts water
60 parts ethylene glycol
10 parts polyethylene glycol 8300
20 parts N-methylpyrrolidone 1
Part 0 of the series! Acid Blue Black IOB (manufactured by Sumitomo Chemical, Acid Black 1) 5 parts water
60 parts diethylene glycol 30 parts N-methylpyrrolidone
10 Parts Example 1 Using each ink obtained in Reference Example 1 above, an on-demand type multi-head (discharge orifice Images of each color were formed using a recording device having a diameter of 35 ILm, a heating resistor resistance of 50 ohms, a driving voltage of 30 volts, and a frequency of 2 KHz.
1) to (T5) were investigated, and as shown in Table 1 below, good results were obtained in all cases.

(TI) Long-term storage stability of ink: After sealing the ink in a plastic film bag and storing it at -30°C and 60°C for 6 months, we observed the precipitation of insoluble matter, changes in liquid physical properties, and changes in color tone. evaluated.

(T2) Ejection stability: Continuous ejection was performed for 24 hours in an atmosphere at room temperature, 5° C., and 40° C., and the quality of the formed image was evaluated.

(T3) Ejection responsiveness: Intermittent ejection every 2 seconds and ejection after being left for 2 months were investigated and evaluated based on the presence or absence of clogging at the orifice tip.

(T4) Light resistance of recorded images: The density of images recorded on the recording materials shown in the table below was measured and evaluated by the rate of decrease in density (%) after being exposed to room light for 6 months.

(T5) Fixability on various recording materials: After printing on the recording materials listed in the table below, the printed area was rubbed with a finger after 15 seconds, and evaluation was made based on the presence or absence of image shift and bleeding.

1-star gMj--Koichi-1-Manufacturer Gin Tamaki Paper Sanyo Kokusaku Pulp ■Seven Stars High quality paper Hokuetsu Paper Co., Ltd. Mutanzhong quality Paper Honshu Paper ■ Toyo Roshi Kotsu 4 Non-size paper Toyo Filter Paper ■Sho , the recorded material temperature is the product name.

Comparative Example 1 An image was formed using each ink of Reference Example 2 in the same manner as in Example 1, and evaluated in the same manner, and the results are shown in Table 1 below.

Example 2 Yellow ink (1) and magenta ink (1) of Reference Example 1
), cyan ink (1), and black ink (1), respectively, and a full-color photographic image was reproduced using the apparatus of Example 1. The resulting image had extremely clear colors and good color reproduction.

Example 3 Yellow ink (2) and magenta ink (2) of Reference Example 1
), cyan ink (2), and black ink (2), respectively, and a full-color photographic image was reproduced using the apparatus of Example 1. The resulting image had extremely clear colors and good color reproduction.

Comparative Example 2 A full-color photographic image was reproduced in the same manner as in Example 1 using the four colors of yellow, magenta, cyan, and black inks of Reference Example 2, respectively. The resulting images had insufficient color reproducibility and were significantly inferior in clarity and light fastness compared to the examples.

(Margin below) -na’；　　　　3 and 2

Claims (1)

[Claims] A method for forming a color image by an inkjet method using yellow, magenta, cyan, and black aqueous inks, wherein one or more dyes represented by the following general formula (I) are used as dyes for the magenta ink. contains one or more dyes represented by the following general formula (II) as a dye for the yellow ink, and one or more dyes represented by the following general formula (III) as a dye for the cyan ink, and A method for forming a color image, characterized in that the black ink contains one or more dyes represented by the following general formula (IV) or (V) as a dye. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (However, in the above formula, R represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a lower acylamino group, a nitro group, or a halogen atom, and X represents an acetyl group, Benzoyl group, para-toluenesulfonyl group, 4-chloro-6-
It represents any hydroxy-1,3,5-triazin-2-yl group, M represents an alkali metal, ammonium or organic amine, l represents 0-2, and m or n represents 0 or 1. ) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (However, Q in the above formula is -NHCONH- or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Represents a bond, and X1
, X2 represents a hydrogen atom, -SO3M, -COOM, or a phenyl group or naphthyl group substituted with a hydroxyl group, R represents a methyl group or a methoxy group, n represents 0 or 1, and M represents an alkali metal, ammonium or Represents organic amines. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) (However, in the above formula, M represents an alkali metal, ammonium, or organic amines, m is 1 to 4, and n is 0.
~3. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(IV) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(V) (However, in the above formula (IV) or (V), R1 is a hydrogen atom, a -SO3M group, or -COOM-substituted phenyl group, R2 represents a hydrogen atom or ▲Numerical formula, chemical formula, table, etc.▼, R3 and R4 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a lower acylamino group, M
represents an alkali metal, ammonium or organic amine, and n is 0 or 1. )(2) The method according to claim (1), wherein the inkjet method is a method that uses thermal energy.