JPH0726047B2 - Ink for ink jet and ink jet recording method using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ink suitable for ink jet recording and an ink jet recording method using the ink, and particularly excellent in long-term storage property and excellent water resistance of recorded matter. The present invention relates to an ink and an ink jet recording method using the same.

[Conventional technology]

As the ink jet recording method, various ink ejection methods (for example, an electrostatic suction method, a method of applying mechanical vibration or displacement to ink by using a piezoelectric element, a method of heating ink and utilizing pressure at that time, etc. are known. Is used to form ink droplets, and a part or all of them are attached to a recording material such as paper for recording.

As the ink to be used, a method in which recording is performed by using a recording liquid (also referred to as ink) in which water and a water-soluble organic solvent as a main component and a dye is dissolved is the mainstream.

In the recording method using this type of ink, although the required items are slightly different depending on the method, the items commonly required are: (1) No bleeding and a good-quality printed image can be obtained. .

(2) The fixing speed of the ink is high.

(3) The durability of the printed matter such as water resistance and light resistance is excellent.

(4) The ink should not be clogged in the nozzle and ink circulation path.

(5) Stable discharge can be obtained over a long period of time.

(6) The ink should not change even after long-term storage.

Etc. are especially important.

In order to satisfy some or all of the above purposes, vigorous studies have been made from both sides of the ink and the device.
A considerable effect has been recognized depending on the required performance.

[Problems to be solved by the invention]

However, in most of the conventional water-based inks described above, a direct dye or an acid dye is used alone as a dye, so if recording is performed by various ink jet methods,
In particular, when paper or cloth whose fibers are exposed on the recording surface is used as the recording material, various problems arise in the fastness, especially in water resistance.

In order to deal with this problem, it has been proposed to use a pigment-dispersed water-based ink (for example, JP-A-56-1478).
59 publication). According to this method, although the robustness of the recorded matter can be satisfied to some extent, the problem of clogging in the nozzle when used as an ink for ink jet, the problem of ink storage stability, It is much more serious than ink.

Therefore, the main object of the present invention is not only designated paper specially prepared for ink jet but also specific recording materials in which fibers are exposed on other specific recording surfaces, especially copy paper, report paper, bond paper, continuous slip paper. Also on a sized general plain paper represented by, it is possible to obtain a recorded material excellent in various fastnesses, especially water resistance.

An object of the present invention is to provide an ink for ink jet and an ink jet recording method using the ink.

Another object of the present invention is to provide an ink which is excellent in storage stability and does not cause clogging, and an ink jet recording method using the ink.

[Means for solving problems]

 The above object is achieved by the present invention described below.

That is, the present invention, first, in a liquid medium containing at least water and an organic solvent, the content of soluble vat dyes 0.1 to 15 wt%, and the content of 0.1 to 10 wt% of an antioxidant. Secondly, an inkjet ink characterized by having both, and secondly, in an inkjet recording method for performing recording by adhering ink droplets formed by an inkjet method to a recording material, the recording material is on a recording surface thereof. The fiber is exposed, as the ink, in a liquid medium containing at least water and an organic solvent, the content of 0.1-15 wt% soluble vat dye, and the content of 0.1-10 wt% oxidation The ink jet recording method is characterized by applying a composition having an inhibitor together.

[Action]

Explaining the present invention in more detail, the main feature of the present invention is that a water-soluble soluble vat dye is used as a coloring material for having high fastness in an ink without using a pigment.

That is, since such an ink is a dissolution type, its dye concentration, viscosity, surface tension, etc. can be changed relatively freely,
In addition, since it does not have insolubles or precipitable components, it does not cause clogging of the ink supply path or nozzles, etc., and unlike conventional inks for ink jet containing pigments, its stability and ink jet suitability are extremely good. There is no problem on the device.

The second feature of the present invention is that the ink further contains an antioxidant. By doing so, it is possible to suppress the generation of insolubles and precipitated components due to the deterioration of the dye in the ink or during the storage of the ink, and the reliability of the ink jet system is significantly improved.

The constituent components of the ink of the present invention or the ink used in the present invention are as described below.

First, the soluble vat dyes that characterize the ink of the present invention,
This is a water-solubilizing type in which a water-solubilizing group such as a sulfone group is introduced into the molecule of a conventional water-insoluble vat dye.

Specifically, for example, CI Solubilized Butt Yellow 1,2,3,4,5,
6,7,8,45,47 CI Soluble Butt Orange 1,2,3,4,6,9,11 CI Soluble Buttled 1,2,3,4,6,8,9,10,11,34,45 CI Soluble Butt Violet 1,2,3,4,5,6,7,8 CI Soluble Butt Blue 1,2,3,4,5,6,7,8,9,41,73 CI Soluble Butt Green 1, 2,3,4,21,30 CI soluble but brown 1,3,5,6,7,38 CI soluble but black 1,2,4,5,6,8,25,61.

These soluble vat dyes are synthesized by a conventional method, or commercially available products are conventionally known purification methods such as reverse osmosis membranes, ultrafiltration membranes, various ion exchange resins, chelating resins, or salting out methods. , Acid precipitation method, centrifugation method, reprecipitation method,
It can be easily obtained by those skilled in the art by performing the solvent suspension washing method alone or in combination.

The content of these soluble vat dyes depends on the type of liquid medium component,
Although it is determined depending on the properties required for the ink, etc., it is generally in the range of 0.1 to 15% by weight, preferably 0.10% by weight, based on the total weight of the ink.

Another aspect of the ink of the present invention or the ink used in the present invention is an ink having a water-soluble anionic dye as a dye in addition to the soluble vat dye. Among them, acid dyes and direct dyes are particularly preferable in view of their characteristics.

The reason for having a water-soluble anionic dye together in the present invention is that the soluble vat dye alone may not be able to obtain a recording having a desired density and color tone due to the solubility in a liquid medium and the restriction due to the molecular structure. The coexistence of a ionic anionic dye solves this problem.

However, when a large amount of the water-soluble anionic dye is used, the high fastness of the recorded matter, which is one of the objects of the present invention, particularly the water resistance is impaired, so the content ratio of the soluble vat dye and the water-soluble anionic dye is 10 1 to 1:10, and the total content of both is preferably 0.1 to 15% by weight, more preferably 0.1 to
The range is 5% by weight.

Next, the antioxidants that characterize the ink of the present invention are those that suppress the autoxidation of the dye that is promoted under the conditions of light and heat. It is roughly divided into three types: substance decomposers and metal deactivators. Specifically, hydroquinone, methylhydroquinone, erythorbic acid, sodium erysorbate, ascorbic acid, isopropyl citrate, dibutylhydroxytoluene, DL-α-tocopherol, nordihydroguaiaretic acid, butylhydroxyanisole, propyl gallate, gallic acid Isoamyl acid, sezamol, quercetin,
Ethyl protocatechuate, β-naphthol, phenyl-
Examples include β (α) -naphthylamine, tetramethyldiaminodiphenylmethane, sulfurized alkylphenols, tributyl phosphite, triphenyl phosphite, etc., but are not limited to these substances. Among the above substances, hydroquinone, methylhydroquinone, erythorbic acid (sodium salt), and ascorbic acid are particularly preferable because they are easily soluble in water.

These antioxidants are preferably used for the total amount of ink.
The range is 0.1 to 10% by weight, and more preferably 0.1 to 5% by weight.

The above are the essential components that characterize the ink of the present invention,
As the liquid medium for dissolving or dispersing the dye and the antioxidant as described above in the ink of the present invention, any medium used as a medium of a conventional general ink for ink jet can be used, for example, other than water. It is preferable to have an organic solvent together, and examples of the organic solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol,
sec-Butyl alcohol, tert-butyl alcohol, isobutyl alcohol, n-pentanol, etc.
Alkyl alcohols of 5; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene Alkylene glycols having an alkylene group of 2 to 6 carbon atoms such as glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol; glycerin; Ethylene glycol monomethyl (or ethyl) ether, Diethylene glycol monomethyl (or ethyl)
Lower monoalkyl ethers of polyhydric alcohols such as ether and triethylene glycol monomethyl (or ethyl) ether; lower dialkyl of polyhydric alcohols such as triethylene glycol dimethyl (or ethyl) ether and tetraethylene glycol dimethyl (or ethyl) ether Ethers: sulfolane, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned.

The above-mentioned solvent is used together with water, but preferably contains at least one water-soluble high-boiling point organic solvent such as diethylene glycol, propylene glycol or glycerin as the solvent. .

The essential components of the ink of the present invention are as described above, but other conventionally known various dispersants, surfactants, viscosity modifiers,
A surface tension adjusting agent, a fluorescent whitening agent, a pH adjusting agent, an antifungal agent, a chelating agent, a reducing agent, etc. can be added as required.

For example, viscosity adjusting agents such as polyvinyl alcohol, celluloses and water-soluble resins; surface tension adjusting agents such as various cationic, anionic or nonionic surfactants, diethanolamine and triethanolamine; pH by buffer solution
A regulator etc. can be mentioned.

Further, in order to prepare the ink used in the ink jet recording method of the type that charges the ink, lithium chloride,
Resistivity adjusting agents such as ammonium chloride and inorganic salts of sodium chloride are added. When applied to an ink jet method in which ink is ejected by the action of thermal energy, thermal physical property values (for example, specific heat, thermal expansion coefficient, thermal conductivity, etc.) may be adjusted.

The ink jet ink of the present invention as described above is required to have a property in which there is little bleeding and good fixability in addition to the fastness on plain paper or cloth on which fibers are exposed. The surface tension at
35-65 dyne / cm, viscosity is 15 cp or less, preferably 8 cp or less,
More preferably, it is desirable to adjust to 3 cp or less.

The above is the outline of the ink of the present invention.

When such an ink is used, clogging in the printer head and long-term storage stability are extremely good as in the case of a conventional water-based ink using a direct dye or an acid dye.

In addition, since a soluble vat dye is used as the dye, the structure of the dye changes to a water-insoluble material in the characters and image area after recording. Can be obtained. This effect is particularly remarkable when the recording surface of the recording material is exposed with fibers, and is particularly remarkable for sized ordinary plain paper.

Next, the present invention will be further described with reference to Reference Examples, Examples and Comparative Examples. In the text, parts or% are based on weight.

Reference Example (Preparation of Dye Used in Examples) Anthrazole Bio-Areto ARR (Anthrasol Viol)
et ARR, trade name; Hoechst) 10 g was dissolved in 490 ml of water. Next, the above aqueous solution was treated with an ultrafiltration device equipped with a membrane filter manufactured by Saatorius Co., Ltd. having an average pore size of 0.01 μm, and the same amount of pure water was added to the stock solution every 250 ml of permeate to repeat the operation 8 times to obtain a dye. A concentrated solution (residual solution) containing particles larger than that was obtained. Further, a membrane filter manufactured by the same company having an average pore diameter of 0.2 μm was set in the same apparatus, and the above concentrated solution was permeated to obtain a permeated liquid containing only a dye.

The permeated liquid was pulverized with a spray dryer to obtain CI-soluble but-biotin 8 used in the present invention.

The soluble vat dyes used in the following examples are those obtained by removing the impurities of the corresponding commercially available dyes by the same purification method as in Reference Example.

Example 1 After all the above components were mixed and stirred for 5 hours, pressure filtration was performed using a Fluoropore Filter FP-100 (trade name, manufactured by Sumitomo Electric Industries, Ltd.) to obtain the ink (A) of the present invention.

Next, the above ink (A) was put in a storage bottle and stored at 40 ° C. for 3 months to evaluate the storage stability of the ink.

Furthermore, the above ink (A) is mounted on an ink jet printer PJ-1080A (trade name, manufactured by Canon) that records using a piezoelectric element, and printed on copy paper and bond paper.
Water resistance and color resistance were evaluated.

Also, perform the capping operation on the print head at 40 ° C.
After left for a month, the printing operation was performed again, and after printing three lines, the printer was turned off and the clogging of 24 nozzles was examined.

The above results and the physical properties of the ink (A) are shown in Table 1.

Examples 2 to 4 Ink (B) Ink (C) Ink (D) Inks (B) to (D) of the present invention were obtained in the same manner as in Example 1 by mixing all the above components. Further, the storage stability, clogging property and water resistance of each ink were evaluated in the same manner as in Example 1, and the evaluation results and the physical properties of the ink are shown in Table 1.

Comparative Example 1 An ink containing no sodium erythorbate (antioxidant) among the constituent components of the ink (A) of Example 1 was prepared in the same manner as in Example 1 to obtain a comparative ink (E) of the present invention. It was Moreover, the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 2 An ink was prepared in the same manner as in Example 1 except that CI dye red 35 was used in place of the dye in the constituent components of the ink (C) of Example 3 instead of the soluble butot violet 8, and was used for comparison in the present invention. Ink (F) was obtained. Moreover, the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 3 Of the above ingredients, ceramic is added to a mixed solution of water and sodium hydroxide, and the mixture is stirred and dissolved at room temperature.

Next, Emulgen 931, ethylene glycol, and the rest of the ingredients were added sequentially, premixed with a stirrer for 2 hours, and further crushed with a ball mill for 20 hours. The mixture was filtered under pressure to obtain a comparative pigment ink (G) of the present invention. Then, the same evaluation as in Example 1 was performed, and the results are shown in Table 1.

* 1 Viscosity measurement Using VISCONIC ELD manufactured by Tokyo Keiki.

* 2 Surface tension measurement Kyowa CBVP Surf Tensiometer A-1 is used.

* 3 Storage stability evaluation 80 g of ink stored in a 100 ml storage bottle (Product name: SHYOTSUTOBIN, D
After storing for 3 months at 40 ° C., the generation of precipitate was visually inspected to evaluate the storage stability of the ink.

○: No precipitation was observed.

× …… Precipitate is generated.

* 4 Water resistance evaluation Commercially available copy paper and bond paper are printed with alphabet letters A to Z, left for 1 day, and then the printed matter is immersed in water for 5 minutes to check for runoff and contamination of the white background. The sex was evaluated.

○: No outflow of printed area or contamination of white background is observed.

△: A part of the printed part spilled out, and there was some contamination of the white background.

×: The printed part leaked, making it difficult to read the characters.
White background pollution is also seen.

* 5 Evaluation of color property A solid print of 3 x 5 cm ² was printed on a commercially available bond paper, and its color vividness was visually evaluated.

◎ …… Very high color clarity.

○: The color is clear.

△: Color vividness is low and dull.

* 6 Evaluation of clogging The evaluation was made based on the number of clogging among 24 nozzles.

○ …… 0 book △ …… 1 to 3 book ………… 4 or more [Effect] According to the ink for ink jet of the present invention and the recording method using the same, not to mention specified paper specially prepared for ink jet. , Recording materials with fibers exposed on other recording surfaces, especially copy paper, report paper, bond paper,
Even on sized ordinary plain paper, which is represented by continuous slip paper, various fastness records, particularly excellent water resistance, can be obtained. In addition, in another aspect of the ink of the present invention, it is possible to perform recording with excellent color resistance in addition to good water resistance.

Furthermore, since the ink used in the present invention is excellent in storage stability, it is possible to perform ink jet recording with good practicality without causing clogging of nozzles and the like.

Claims (7)

[Claims] 1. A liquid medium containing at least water and an organic solvent, wherein a soluble vat dye having a content of 0.1 to 15% by weight and an antioxidant having a content of 0.1 to 10% by weight are used together. Characteristic ink-jet ink. 2. The surface tension at 25 ° C. is 35 to 65 dyne / cm,
The inkjet ink according to claim 1, which has a viscosity of 15 cp or less. 3. The ink-jet ink according to claim 1, which further contains a water-soluble anionic dye. 4. An ink jet recording method for recording by recording ink droplets formed by an ink jet method on a recording material, wherein the recording material has fibers exposed on its recording surface. In a liquid medium containing at least water and an organic solvent, a composition having a content of 0.1 to 15% by weight of a soluble vat dye and a content of 0.1 to 10% by weight of an antioxidant is applied. Characteristic inkjet recording method. 5. The ink jet recording method according to claim 4, wherein the recording material is sized paper. 6. The surface tension of the ink at 25 ° C. is 35 to 50.
The ink jet recording method according to claim (4), which has a viscosity of 65 dyne / cm and a viscosity of 15 cp or less. 7. The ink jet recording method according to claim 4, wherein the ink further contains a water-soluble anionic dye.