JPH03782A - Ink and recording method - Google Patents

Abstract

PURPOSE:To realize the formation of an ink satisfying general requirements for performance and capable of giving an image free from the problem of discoloration even on a coated paper by using a specified die. CONSTITUTION:An ink containing at least a dye and medium carrying it, wherein a dye of formula I is used. In formula I, M is an alkali metal, an ammonium group or an organic quaternary ammonium; R1 and R2 are each methoxy, ethoxy or acetylamino; R3 is H, ethoxy or a sulfonate group represented by SO3M; R4 is H or OH; X is H, acetyl, benzoyl,-SO2C6H5,-SO2C6H4CH3 or a group of formula II; R5 and R6 are each H or C2H4OH.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an ink and a recording method using the same, and more particularly, an aqueous ink that provides an image with improved indoor discoloration property, and a recording method using the ink. In particular, it relates to an inkjet recording method.

(Prior Art) Conventionally, water-based inks in which water-soluble dyes are dissolved in an aqueous medium have been used as inks for fountain pens, feltbens, etc., and inks for inkjet recording. A water-soluble organic solvent is generally added to prevent ink from clogging in ink discharge nozzles.

These conventional inks must provide an image with sufficient density, be free from clogging at the pen tip or nozzle, dry well on the recording material, have little bleeding, and be stable during storage. In particular, in the case of an inkjet system that uses thermal energy, it is required to have excellent heat resistance, and the image formed is also required to have sufficient light resistance, water resistance, etc.

For example, C,1 and Food Black 2 have been used for both monochrome and full-color images, and the most important inks have been C,1 and Food Black 2, taking into consideration the above-mentioned performance requirements (Japanese Patent Laid-Open No. 59-93766 and the same). 59-93768
In addition, Japanese Patent Publication No. 62-010274 discloses an ink that takes ejection stability, light resistance of images, etc. into consideration.

(Problems to be Solved by the Invention) Among the various required performances mentioned above, durability of the formed image is particularly important.

In the past, problems with image durability were primarily due to fading due to direct sunlight and various types of illumination light, and these fading problems have been solved by selecting dyes with excellent light resistance.

However, recently, in addition to these fading problems, the problem of image discoloration has been attracting attention. In other words, images made with conventional ink suffer from not only fading (but also discoloration), and the effect of this is especially serious when using black ink, which is used in large quantities.In the case of full-color images, this discoloration can cause image quality to deteriorate. This rapidly decreases and becomes an important problem in image formation.

This discoloration problem progresses even indoors where there is no direct sunlight, and discoloration is also accelerated by the type of recording material used to form the image.
With Black 2, this problem of discoloration was unavoidable.

In the case of so-called coated paper, in which an ink-receiving layer containing a pigment and a binder is formed on a base material such as paper, in order to improve image quality such as ink color development, clarity, and resolution, Even with inks that have little problem of discoloration, significant discoloration occurs, and this problem cannot be solved simply by selecting a dye with good light resistance.

Therefore, it is an object of the present invention to provide an ink and a recording method that can satisfy the general required performance as described above, and can also provide an image that does not cause the problem of discoloration even on coated paper.

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

That is, the present invention provides an ink containing a small amount of dye and a medium supporting the same, characterized in that the dye is a dye represented by the following expression (1), and a recording method using the ink. It is.

(Left below) (In the above general formula, M is an alkali metal, an ammonium group, or an organic quaternary ammonium, R1 and R2 are a methoxy group, an ethoxy group, or an acetylamino group, and R3 is a hydrogen atom, an ethoxy group, or an SO, A sulfonic acid group represented by M, R4 is a hydrogen atom or a hydroxyl group, X is a hydrogen atom,
Acetyl group, benzoyl group, -SO□CaHs, -3o
□C6)1. CH3 or (Function) By using the dye of general formula (I) as the dye of the ink, an ink that provides an image with little discoloration on coated paper is provided.

Further, in the second aspect of the present invention, it is possible to provide an image with little discoloration on coated paper using the above ink.

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

The black dye used in the present invention is represented by the general formula (I), and the substituents R1 to Rs, M and X are all as described above. More preferably, a dye in which X is a substituent other than hydrogen is used. In addition, all of these dyes are generally soda salts of water-soluble groups such as sulfonic acid groups, but the present invention is not limited to these sodium salts, and their counter ions are potassium, lithium, ammonia, phosphonium, Organic amines such as alcohol amines have the same effect, and the present invention also includes dyes containing counter ions other than these.

Specific examples of the dye represented by the above general formula (I) include the following dyes, but are not limited to these dyes.

(The following are blank spaces) No, 1 No, 5 No, 2 No, 6 NO13 No, 7 No, 8 No, 4 No, 9 No, 13 No, 14 No, 11 No, 12 The above dyes are known azo dyes. It can be produced according to the synthesis of As an example, the above No. 3 and No.
An example of the synthesis of dye No. 8 is given below.

(No, 3) Hw! Disperse 0.1 mol in water at 500m℃, add 0.3 mol of hydrochloric acid
Add moles and cool on ice. 0.1 mol of sodium nitrite and 50 mol of water
A solution dissolved in mJ2 is added under stirring at 10° C. or lower to diazotize. Separately, 0.1 mol of H acid was dispersed in 500 mj2 of water, and the pH was adjusted to 6 to 7 with caustic soda to form a solution.
Add the above diazonium salt solution to this for coupling, and stir for 1 hour (pH 4 to 5, temperature about 5
). 920.1 mol of Jetoxiayu and 300 mol of water
mf2, diazotized in the same manner as above, and added to the above solution for second coupling (pH: 8 to 9, temperature: about 5°C). After stirring for 2 hours, potassium chloride was added to precipitate the dye, which was collected by filtration. Impurities are removed by repeating the process of dissolving this in water again to make a concentrated solution, salting it out with potassium chloride, and collecting it by filtration.At the same time, the counter ions of the dye are converted to potassium ions, and an ultrafiltration device (
After desalting and purifying using a dye powder (manufactured by Sartorius), the solution was evaporated to dryness to obtain dye powder No. 3.

(No. 81 Dye powder of No. 38 was obtained in the same manner as above, except that 1-naphthylamine-6-sulfonic acid and dimethoxyaniline were used as raw materials for diazotization, and salt was used for salting out.

The amount of the dye used in the ink of the present invention is not particularly limited, but - for boat fishing, 0.1 to 15% by weight, preferably 0.3 to 10% by weight, more preferably 0.3 to 10% by weight of the total amount of ink; An amount of 0.5 to 6% by weight is preferred.

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. Further, the water is not ordinary water containing various ions (it is preferable to use deionized water).

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, isobutyl alcohol, and n-butyl alcohol. - Alkyl alcohols having 1 to 5 carbon atoms such as pentanol; amides such as dimethylformamide and dimethylacetamide; ketone or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene Polyalkylene glycols such as glycol and polypropylene glycol: ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1. ．． 2.6-hexanetriol, thiodiglycol, hexylene glycol,
Alkylene glycols in which the alkylene group contains 2 to 1 carbon atoms, such as diethylene glycol; glycerin;
Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol Lower dialkyl ethers of polyhydric alcohols such as dimethyl (or ethyl) ether; sulfolane, N-methyl-2-pyrrolidone, 1
, 3-dimethyl-2-imidazolidinone and the like.

An appropriate organic solvent is selected and used from the above organic solvents, but glycerin or polyethylene oxide with a degree of polymerization of 2 to 6 is particularly good for preventing ink clogging, and N-methyl -2-pyrrolidone, 1,
Nitrogen-containing cyclic compounds such as 3-dimethyl-2-imidazolidinone or monoether compounds of polyalkylene oxides such as diethylene glycol monomethyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether are good (and also have good frequency response). It is preferable to use a lower alcohol such as ethyl alcohol, n-propyl alcohol, or isopropyl alcohol, or a surfactant. Therefore, in the present invention, preferable solvent compositions include, in addition to water,
Among the above, combinations of anti-clogging agents and frequency response, combinations in which a solvent is added in consideration of image density and ejection stability, or the simplest system is combinations of anti-clogging agents and water. A combination of solvents consisting of:

The content of the water-soluble solvent in the ink is generally 2 to 80% by weight, preferably 3 to 70% by weight of the total weight of the ink.
% by weight, more preferably in the range from 4 to 60% by weight.

In addition, the water used should account for 35% or more, preferably 45% or more by weight of the entire ink. If the amount of water is small, the formed image will contain a large amount of low-volatile organic solvent (remaining dyes). This is not preferable because it causes problems such as migration of images and blurring of images.

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. Examples of pH adjusting agents used in the above ink include various organic amines such as jetanolamine and triethanolamine, and inorganic inorganic hydroxides such as alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide. Examples include alkaline agents, organic acid salts such as lithium acetate, organic acids, and mineral acids.

The ink of the present invention as described above has a viscosity of 1 at 25°C.
20 cP to 20 cP, preferably 1 to 15 cP, and a surface tension of 30 dyne/cya or more, preferably 40 d
It is preferable to have physical properties of yne/am or more and a pH of about 4 to 10.

The recording method of the present invention is a recording method characterized by using the above-mentioned ink, and the recording method and recording material are not particularly limited, but in particular, the recording method is an inkjet method, and the recording material is coated paper. A method using the following is particularly effective.

The inkjet method may be any conventionally known method (although it is not particularly limited, in the present invention, for example, the method described in Japanese Patent Application Laid-Open No. 54-59936 is used, in which the ink is heated by the action of thermal energy). Particularly useful is a method in which a sudden change in volume is caused and ink is ejected from a nozzle by the force exerted by this state change.

That is, with this method, in the case of conventional ink, there was a risk that foreign matter would settle on the heat-generating head in the device, causing problems such as ink failure to eject, but the ink of the present invention is free from such foreign matter. Stable recording is possible because no deposits occur.

The recording material used in the present invention can be any recording material such as general plain paper, high-quality paper, coated paper, plastic film for OHP, etc., but it is especially noticeable when coated paper is used. A great effect is produced.

These coated papers are made of paper such as plain paper or high-quality paper, and have an ink-receiving layer that serves as a pigment and binder on the surface to improve color development, clarity, dot shape, etc. with ink. That is.

In the case of these coated papers, fine pigments such as synthetic silica with a BET specific surface area of 35 to 650 rrl'/g are used as pigments to provide images with excellent color development and clarity, but conventional inks cannot be used. When used, the problem is that the image discolors over time, although the theoretical reason for this is unknown, and this is a serious problem not only for black monochrome images but also for full color images. In addition, similar to these coated papers, recording materials that have a thin layer of pigment and binder on a paper base material, and in which fibers of the base paper are mixed, also cause similar problems. There is.

It has been confirmed that the above-mentioned discoloration problem does not occur even when a black monochrome image or a full-color image is formed using the ink of the present invention on the above-mentioned coated paper. Therefore, according to the method of the present invention, the BET specific surface area is 35 to 6.
Not only coated paper using a pigment of 50rrr/g, coated paper using a pigment with a BET specific surface area of less than that, but also plain paper and other arbitrary recording materials can be used to record images that do not cause discoloration indoors for a long time. can be provided.

Incidentally, the recording method using the inkjet method and the various recording materials described above are publicly known, and various proposals have been made by the applicant and others, but these recording methods and recording materials may be used as they are in the present invention. Can be used.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. Note that the text in the middle of the text is based on weight unless otherwise specified.

Examples 1 to 7 The following components were mixed and sufficiently stirred to dissolve, and then filtered through a Fluorobor filter (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 0.22 μm to prepare inks of the present invention.

Example of 1 dish: Exemplary dye No. 1 3 parts diethylene glycol 20 parts N-methyl-2-pyrrolidone 5 parts ion-exchanged water
72 parts Futoyoyu Exemplary dye No. 2 2 parts diethylene glycol 30 parts ion-exchanged water 68 parts Dish 1 Exemplary dye No. 3 3 parts diethylene glycol 15 parts ethanol 5 parts ion-exchanged water
77 Parts Phlebotomy Doctor A Exemplary dye No. 4, 3 parts Glycerin N-methyl-2-pyrrolidone ion exchange water 2 parts Exemplary dye No. 5 Ethylene glycol Ethanol ion exchange water 1 Blood reciprocal Exemplary dye No. 6 Diethylene glycol 1.3-Dimethyl-2-imidazoliethanol Ion-exchanged water mixed with soil Exemplary dye No. 8 Triethylene glycol glycerin Ethanol Ion-exchanged water 15 parts 10 parts 72 parts 3 parts 20 parts 5 parts 72 parts 3 parts 10 parts Zinone 8 parts 5 parts 74 parts 3 parts 10 parts 7 parts 3 parts 77 parts Exemplary dye No. 10 2.5 parts Diethylene glycol 25 parts Ion exchange water 72.5 parts Exemplary dye No. 11 4 parts Ethylene glycol 15 parts N-methyl-
2-pyrrolidone 10 parts ion exchange water
71 parts Exemplary dye No. 13 2 parts diethylene glycol 15 parts triethylene glycol 10 parts ion exchange water
73 parts Comparative Examples 1 to 4 Inks of comparative examples were prepared in the same manner as in the examples.

Le School Plate Craftsman The dye of Example 1 is represented by the following structural formula c, r.

An ink having exactly the same composition as in Example 1 except that Food Black 2 was used.

An ink having exactly the same composition as in Example 3 except that the dye in Example 3 was changed to C.1 and Direct Black 62.

An ink having exactly the same composition as Example 5, except that the dye in Example 5 was changed to C,1, Direct Black 118.

Soil Color A: An ink having exactly the same composition as in Example 7, except that the dye in Example 7 was changed to C1L Acid Black 60 represented by the following structural formula.

Comparative Example 5 An ink having the same composition as Example 6 except that a dye represented by the following structural formula was used in place of the dye of Example 6.

Usage Example The inks of Examples 1 to 9 and Comparative Examples 1 to 4 were installed in an inkjet printer BJ-80A (manufactured by Canon, nozzle size 50 x 40 μm, number of nozzles 24) that uses a heating element as an ink ejection energy source. When printing on recording materials A to C, we evaluated clogging during reprinting after a printing stop, clogging recovery and color fastness during reprinting after a long printing stop, and evaluated the results. It is shown in Table 1 and Table 2.

Recording material A: Color Bubble Jet Cobia designated paper (manufactured by Canon ■) Recording material B: Inkjet Coco-5 Paper Matte Coat NM (trade name, manufactured by Mitsubishi Paper Mills) Recording material C: Paintjet designated paper (Hieret Co., Ltd.) (Manufactured by Barakad Co., Ltd.) (Evaluation method and evaluation basis II) (1) Clogging when reprinting after printing - The printer is filled with the specified ink and alphanumeric characters are continuously printed on the recording material C for 10 minutes. After printing, the printing was stopped, and after leaving it for 10 minutes without a cap, etc., alphanumeric characters were printed again and judged by the presence or absence of defects such as faded or missing characters (20 ± 5 ° C, (Left at 50±1O%RH)
.

O: No defects from the first character.

Δ: Part of the first character is faded or missing.

×: The first character is full (cannot be printed).

(2) Recovery from clogging when reprinting after a long printing stop After filling the printer with the specified ink and printing alphanumeric characters on the recording material C continuously for 10 minutes, stop printing and replace the cap, etc. Leave it for 7 days (60°C 110±
After leaving it at 5% RH), a recovery operation for nozzle clogging was performed, and the number of recovery operations until normal printing without blurring or missing characters was possible was determined.

○: Normal printing is possible after 1 to 5 recovery operations.

△: Normal printing is possible after 6 to 10 recovery operations.

×: Normal printing is possible after 11 or more recovery operations.

(3) Color-fastness After printing a solid black pattern of 10 mm x 30 mm on recording materials A, B, and C, the ozone concentration is always maintained within the range of 0.1 ± 0.05 parts by volume as a method of accelerating discoloration. The printed matter was left in a light-shielded tank for 60 minutes, and the color difference (ΔE"ab) of the printed matter before and after the test was measured (according to JIS 28730).

0: ΔE”ab<5 0:5≦ΔE”ab≦10 △:lO<ΔE”ab<20 ×: ΔE”ab≧20 CoU Paper (A) OQOOOQOQQQ Paper (BJ OOOOOOOOOO0 Paper (C) OOOOOOO000Q (3 ) Paper (A) X X X X X Paper (B) x x x x x Paper (C) x
X x x It has become possible to form images that not only have excellent performance such as ink clogging resistance required for boat fishing, but also have excellent color fastness.

Claims (6)

[Claims] (1) An ink containing at least a dye and a medium supporting the same, characterized in that the dye is a dye represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the above general formula, M is an alkali metal, an ammonium group, or an organic quaternary ammonium, and R_1 and R_2
represents a methoxy group, ethoxy group or acetylamino group, R
_3 is a hydrogen atom, an ethoxy group or a sulfonic acid group represented by SO_3M, R_4 is a hydrogen atom or a hydroxyl group, X is a hydrogen atom, an acetyl group, a benzoyl group, -SO_2C_
6H_5, -SO_2C_6H_4CH_3 or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R_5 and R_6 represent hydrogen atoms or C_2H_4OH. ) (2) Contains 0.5 to 10% by weight of the dye of general formula (I) and 2% of polyhydric alcohol or polyhydric alcohol ether.
The recording method according to claim 1, wherein the recording method contains 80% by weight. (3) A recording method performed by applying ink to a recording material, characterized in that the ink contains at least a dye and a medium supporting the same, and the dye is a dye represented by the following general formula (I). recording method. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the above general formula, M is an alkali metal, an ammonium group, or an organic quaternary ammonium, and R_1 and R_2
represents a methoxy group, ethoxy group or acetylamino group, R
_3 is a hydrogen atom, an ethoxy group or a sulfonic acid group represented by SO_3M, R_4 is a hydrogen atom or a hydroxyl group, X is a hydrogen atom, an acetyl group, a benzoyl group, -SO_2C_
6H_5, -SO_2C_6H_4CH_3 or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R_5 and R_6 represent hydrogen atoms or C_2H_4OH. ) (4) The recording method according to claim 3, wherein recording is performed using an inkjet method. (5) The recording method according to claim 3, wherein the inkjet method is a method in which thermal energy is applied to the ink and the ink is ejected as droplets from micropores. (6) The recording method according to claim 3, wherein the recording material has an ink-receiving layer made of a pigment and a binder on its surface.