JPS6319288A - Color image forming method - Google Patents

Abstract

PURPOSE:To obtain an image having excellent water resistance, light resistance, abrasion resistance or the like, by using magenta, yellow, cyan and black water- based inks, and incorporating at least one dye of a respectively specified formula into each of the magenta, yellow and cyan inks. CONSTITUTION:At least one dye of formula (I) is incorporated in a magenta ink, at least one dye of formula (II) is incorporated in a yellow ink, and at least one dye of formula (III) is incorporated in a cyan ink. By the use of these water-based inks and a water-based black ink, a color image is formed by an ink jet system.

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 magenta, yellow, 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,
In this method, ink droplets are formed using a method that utilizes the pressure generated at that time, and some or all of these droplets 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 color tone.

However, there has been no known method for forming color images using ink that satisfies all of these characteristics (1) to (5).

Therefore, the invention of an inkjet method that satisfies (1) to (5) is disclosed in JP-A-57-195775 and JP-A-57-1.
No. 9719, No. 58-12786, No. 59-9696
As disclosed in Publication No. 7, etc., the inks used in this method satisfy the above performance (1) to (5) when viewed as individual inks such as magenta, yellow, and cyan, but color images The three primary color inks used to form the image are unsatisfactory, as the color rendition of intermediate colors is insufficient overall, and they are inferior to silver halide photography in various aspects such as light fastness and water resistance. It is something.

Accordingly, an object of the present invention is to provide an inkjet system that fully satisfies all of the requirements (1) to (5) above in a well-balanced manner and provides excellent color images.

The present inventors conducted intensive research to achieve the above object and found that the properties (1) to (5) 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 discovered that a specific combination of dyes is a dye suitable for a color image forming method that satisfies all of the characteristics (1) to (5) above. This led 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 magenta, yellow, cyan, and black aqueous inks, wherein the dye of the magenta ink is represented by the following general formula (I). containing one or more dyes represented by the following general formula (II) as the dye of the yellow ink,
This is a method for forming a color image, characterized in that the cyan ink contains one or more types of dyes represented by the following general formula (m).

(However, R1 in the above formula represents a hydrogen atom or an alkyl group, R2 represents a hydrogen atom or a halogen atom, and R3
represents a hydrogen atom or -(Cm)12m)OH, l is 0 or 1, m is 1.2 or 3, and n is 1
or 2, and M represents an alkali metal, ammonium or organic amines. ) (However, A in the above formula
-NllCONll- or -5o3M, -COO
M represents a phenyl group or a naphthyl group which may be substituted with a hydroxyl group, R represents a methyl group or a methoxy group, n represents O or 1, and M represents an alkali metal, ammonium or an organic amine. ) However, in the above formula, M represents alkaline earth metal ammonium or j7T amines, m is 1-4, and n is 1-3.

Next, to explain the present invention in more detail, it is natural that dyes for aqueous ink used in inkjet systems are required to have various performances, but especially when forming color images, dyes such as magenta, yellow, etc. It is important that the light resistance, water resistance, and other properties of the black and black dyes are well-balanced, and that the color rendering relationship between them is good. However, through detailed research by the present inventor, the most excellent color image formation using the inkjet method was realized by combining a group of specific dyes as described below. be.

The dyes represented by the above general formulas (I) to (m) used in the present invention and which mainly characterize the present invention may be any dye as long as it is included in the above general formulas (I) to (m). Although these are good, 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.

Magenta Dye M-30 No. 1 Colorant Y-1 Y-Z As the dye for the black ink in the present invention, any conventionally known black dye can be used.
Particularly preferred when used in combination with the above magenta, yellow and cyan inks, the following general formula (
They are dyes represented by IV) to (VI).

However, in the above formula (TV), X is a hydrogen atom, -5o
, represents a phenyl group or naphthyl group optionally substituted with a group of M or -NtlCOCR+, R, represents a hydrogen atom, a phenyl group substituted with -503M or -COOM, or -CM, SO, M, R2 represents represents an elementary atom or , M represents an alkali metal, ammonium or a residual amine, and n is 0h)1.

O However, in the above formula (V), X represents a hydrogen atom, a lower alkyl group, or a phenyl group optionally substituted with a -503M'' group, m represents O or 1, and M represents an alkali metal, ammonium or Represents amines, A,
B and C represent a benzene ring or a naphthalene ring which may have a substituent. However, B and C do not represent a naphthalene ring at the same time.

However, A or B in the above formula represents a benzene ring or a naphthalene ring which may have a substituent, m is 0,
or 1, and M represents an alkali metal, ammonium or amines.

In the present invention, black dyes other than those mentioned above can also be used, such as (:, 1. Direct Black 17. 19.
32.62.71, +08, 146, 154, (
:, 1. Acid Black 2.7, 24.26.31.
52.63, +12.118, etc. are also useful, and these dyes can be used alone, in mixtures, or in combination with the preferred dyes listed above. In particular, among the black dyes having the above general formula, dyes suitable for combination with the three primary color dyes are those represented by the following structural formula.

Black sugar B-1 H K-2 Leaf B-3 H K-4 B-5 K-6 The aqueous ink used in the present invention has the above general formula (I
) ~ (I[I) Water-based inks of the three primary colors of magenta, yellow, and cyan are prepared using the dyes represented by I, and a black water-based ink is further prepared. The preparation method itself may be in accordance with conventional techniques. Further, the three primary color aqueous inks used in the present invention have the general formulas (I) to (I[
In addition to the need to include one kind of dye of I) or a plurality of dyes of the same color, other dyes not included in general formulas (I) to (I[+)] are used to adjust the tone of each aqueous ink. dyes may also be included. The black ink can be prepared from any black dye, but preferably from the dye of the general formula (IV) to (''/I)';
J! 4 points.

The content of each of the above-mentioned specific dyes in the ink is determined depending on the type of liquid medium component, the properties required of the ink, etc., but generally, the content of each of the above-mentioned specific dyes in the ink is 0.00 mt pepper in 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 as a solvent, which has the effect of preventing the drying of the ink. Further, as water, it is preferable to use deionized 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; Ketones or keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylenes such as polyethylene glycol and polypropylene glycol Glycols: ethylene glycol, propylene glycol, butylene glycol,
Alkylene glycols containing an alkylene group or 2 to 6 carbon atoms such as tosoethylene glycol, 1゜2.6-hexandriol, thiodiglycol, hexylene glycol, diethylene glycol: Glycerin: Ethylene glycol methyl (or ethyl) Lower alkyl ethers of polyhydric alcohols such as ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether: N-
Examples include methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone. 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 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. range.

The water content at this time may be determined within a wide range depending on the type of solvent component, its composition, or the desired characteristics of the ink, or it may be determined in a wide range from 10 to 10% in the total ff1ffi of the ink.
90%, preferably 10-70%, more preferably 20%
This is considered to be within the range of ~70%.

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.

In addition, when applied to an inkjet method that ejects ink by the action of thermal energy, thermal physical property values (e.g., specific heat, thermal coefficient, thermal conductivity, etc.) may be adjusted. be.

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
n Industry Application
ns) Vol, JA-13, No. l (1977
(February/March issue), Nikkei Electronics, 4/1976
January 19th issue, January 29th, 1973 issue, and May 6th, 1974 issue. The methods described in these are
Some of them are suitable for the present invention, and some of them are explained below.
First, there is the electrostatic suction method. In this method, a strong electric field is applied between the nozzle and an accelerating electrode placed a few mm in front of the nozzle, and the ink is drawn out from the nozzle one after another as particles, and the drawn ink is deflected. There is a method in which an information signal is applied to the deflection Ti pole while the ink particles fly between the electrodes for recording, and a method in which the ink particles are ejected in response to the information signal without deflecting the ink particles, both of which are applicable to the present invention. It is valid.

The second method is to apply high pressure to the ink with a small pump and mechanically vibrate the nozzle with a crystal drifter, etc., to forcibly eject minute ink particles. Simultaneously with the injection, the fuel is charged in accordance with 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 conventionally large nozzle diameter.

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 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. 36, in which ink subjected to the action of thermal energy undergoes a sudden change in volume, and the acting force resulting from this change in state 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
Even if you use plastic sheets for HP, it is naturally possible to record excellent records, and other paper that is widely used for office purposes such as copy paper, report paper, pound paper, slip paper, continuous slip paper, and computer presses. Any type of paper can be used, and these papers can be either low-size paper or high-size paper.

According to the present invention as described above, the dyes used in the three primary colors of magenta, yellow, and cyan used in the present invention have the same level of dissolution stability and storage stability in the liquid medium. Due to its excellent stability, it is suitable as a water-based ink for general inkjet methods, and in particular, all dyes have well-balanced and excellent light fastness, water resistance, clarity, mutual color rendering properties, etc. , can give excellent quality color images.

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 three colors: magenta, yellow, and cyan. Since water-based inks with various suitability were not known, it was not possible to provide blurred color images, especially in inkjet systems that use thermal energy. By selecting and combining dyes into three primary color water-based inks, and using this in combination with a black water-based ink, it has been possible to provide color images of superior quality to a degree not possible with the prior art.

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 The following components were mixed, and then filtered under pressure through a Teflon filter with an average pore size of 0.45 μm and degassed to obtain each of the magenta, yellow, cyan, and black aqueous inks used in Example 1. Prepared.

Magenta ink 1 Exemplary dye M-12 parts Water 70 parts Diethylene glycol 25 parts Glycerin
3 parts yellow ink 1) Exemplary dye Y - 13 parts water 69 parts diethylene glycol 25 parts glycerin
3 parts cyan ink 1 part exemplary dye cy-t 4.5 parts water
67.5 parts diethylene glycol 25 parts glycerin
3 parts Bootsquink 1 Exemplary dye Bk - 23 parts Exemplary dye Bk - 42 parts Water 67 parts Diethylene glycol 25 parts Glycerin
3 parts Magenta ink 2 Exemplary dye M-23 parts Water 69 parts Diethylene glycol 25 parts Glycerin
3 parts Yellow ink 2 Exemplary dye Y-23 parts Water 69 parts Diethylene glycol 25 parts Glycerin
3 parts, 1 part, 1 part, 2 parts, 1 example dye, cy-z, 4.5 parts, water.
67.5 parts diethylene glycol 25 parts glycerin
3 parts Black ink 2 C,1, Direct Black 62 3 parts Exemplary dye Bk-52 parts Water 67 parts Diethylene glycol 25 parts Glycerin
3 parts Reference Example 2 In place of the dye in Reference Example 1, the other four parts were the same as in Reference Example 1, magenta, yellow, cyan, and black, respectively.
Water-based inks for each color were prepared.

Magenta Ink Edible Red No. 104 (Phloxine, Acid Red-92
, manufactured by Daiwa Kasei) Yellow ink Edible Yellow No. 4 (Tartrazine, Acid Yellow 23,
(manufactured by Daiwa Kasei) Cyan ink Edible blue No. 1 Brisoin blue, Acid blue 9,
(Manufactured by Daiwa Kasei) 1 sentence Acid Blue Black 10B (Manufactured by Sumitomo Chemical, Acid Black 1) Example 1 Using each ink obtained in Reference Example 1 above, heat was applied to the ink in the recording head. A recording device with an on-demand type multi-head (discharge orifice diameter 35 μm, heating resistor resistance value 50 ohms, drive voltage 30 volts, frequency 2 Hz) generates droplets by applying energy and performs recording. Form an image of each color and use the following (TI
) to (T5), all of them yielded good results as shown in Table 1 below.

(T,) 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. It was 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.

(Ts) 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.

Surname & Match Company Name - Note 1 Question 1 Manufacturer Gin Tamaki Paper Yamama Kokusaku Valve - Seven Stars Paper Hokuetsu Paper - White Botan Medium Quality Paper Honshu Paper ■ Toyo Roshi No. 4 Non-size paper Toyo Roshi Paper ■ Still, recorded The material name 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.

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96% 96% 90%- Good Good Good Good procedure correction (i (voluntary) October 7, 1986

Claims (3)

[Claims] (1) In a color image forming method using an inkjet method using magenta, yellow, cyan, and black aqueous inks, the magenta ink contains one or more dyes represented by the following general formula (I) as dyes. , the following general formula (I
A method for forming a color image, comprising one or more types of dyes represented by I), and one or more types of dyes represented by the following general formula (III) as the dye of the cyan ink. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (However, R_1 in the above formula represents a hydrogen atom or an alkyl group, R_2 represents a hydrogen atom or a halogen atom,
R_3 represents a hydrogen atom or -(CmH_2m)OH, l is 0 or 1, m is 1, 2 or 3,
n is 1 or 2, and M represents an alkali metal, ammonium or organic amines. ) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (However, A in the above formula is -NHCONH- or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Represents a bond, and X_
1. 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 1.
~3. ) (2) As a dye for black ink, the following general formula (IV) is used.
The method for forming a color image according to claim (1), which contains one or more types of dyes represented by (VI). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(IV) (However, in the above formula (IV), X represents a phenyl group or a naphthyl group that may be substituted with a -SO_3M group or -NHCOCH_3, and R_1 is a hydrogen atom. ,-S
Represents a phenyl group or -CH_2SO_3M substituted with O_3M or -COOM, R_2 represents a hydrogen atom or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, M represents an alkali metal, ammonium or organic amines, n is 0 Or 1. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(V) (However, in the above formula (V), X represents a hydrogen atom, a lower alkyl group, or a phenyl group which may be substituted with a -SO_3M group, and m is 0 or 1, M represents an alkali metal, ammonium or amines, A
, B and C represent a benzene ring or a naphthalene ring which may have a substituent. However, B and C do not represent a naphthalene ring at the same time. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(VI) (However, A or B in the above formula represents a benzene ring or naphthalene ring that may have a substituent, and m is 0.
, or 1, and M represents an alkali metal, ammonium or amines. ) (3) As the dye of formula (I), claim No.
The method for forming a color image according to item 1). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (VII) (However, in the above formula (VII), M represents Cu or Co, Q represents a naphthalene nucleus, n represents 1 or 2, W represents an alkali metal, Represents ammonium or amines.However, in Q, the azo group and the -O- group are located in the ortho position.)