JPH08283637A - Ink for ink jet recording and recording - Google Patents

Abstract

PURPOSE: To obtain a recording ink giving a high coloring and a high printing quality especially in a plain paper, reducing or eliminating bleed in color mixing and further having high water resistance of image by incorporating a specific coloring agent and an alginate, etc., in the ink. CONSTITUTION: The objective ink includes at least (A) a coloring agent (dye) having a carboxyl group in the structure, (B) an alginate in a concentration of 0.02-0.5wt.%, (C) 0.5-20wt.% wetting agent, (D) at least one kind of penetrating agent selected from among derivatives of (i) a surfactant having <= a critical micelle concentration, (ii) 1-10wt.% a monohydric alcohol and (iii) 0.5-5wt.% a polyhydric alcohol, and (E) water. Furthermore, the ink preferably includes (F) a fluorine-based surfactant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an ink capable of realizing high-quality printing, especially on plain paper, and reducing or eliminating color bleed in ink jet recording.

[0002]

2. Description of the Related Art In the ink jet recording system, inks having various compositions have been proposed for the purpose of high quality recording. A recent trend is that bleeding (hereinafter referred to as bleed) that occurs when printed images have high color development when printed on plain paper that is commonly used in offices, etc. A variety of reduced inks have been proposed.

In Japanese Patent Laid-Open No. 5-194884, a polymer colloid and at least one surfactant having a critical micelle concentration (hereinafter referred to as cmc) or more and a low vapor pressure solvent are added to the ink to cause bleeding on recording paper. It is reducing.

On the other hand, in JP-A-6-88048,
Use a recording ink in which the added amount of the surfactant is cmc or more with respect to the ink and cmc or less with respect to pure water, and prevent the bleeding between the recording medium and the ink and the bleeding of the color boundary due to the effect of the surfactant. ing.

[0005]

However, the above-mentioned technique has the following problems.

First of all, the ink penetrates deeply into the paper because the penetrability is enhanced for the purpose of improving the color bleed of the recorded image.

Therefore, in the shape of dots on the recording medium, there is a problem that the sharpness around the dots is lacking and the edges of the recorded image are blurred. Further, there is a problem that the coloring property of the printed matter is deteriorated due to the permeability of the recording ink. Generally, in order to make the dot shape sharper, it is sufficient to suppress the penetration of ink, but when using multiple inks such as in color printing, the remaining ink that has not dried on the recording medium mixes with each other. It causes bleeding and deteriorates the image.

The second problem is that there is a concern that the amount of added surfactant of cmc or more may cause bubbling of the ink, and problems remain in the reliability of the ink and the ejection stability of the ink from the print head. That is the point.

As described above, in general, the quality of recording on plain paper is still insufficient.

Accordingly, it is an object of the present invention to provide an ink jet recording ink and a recording method capable of reducing or eliminating color bleeding in mixed colors, and further capable of producing a recorded image with high color development and sharp print quality. .

[0011]

[Means for Solving the Problems] Various investigations have been carried out to achieve the above-mentioned problems. As a result, high color development and high print quality are achieved to reduce or eliminate bleeding in mixed colors, and The present invention has been accomplished by finding a high recording ink and a high recording method.

That is, at least (A) a colorant (dye) having a carboxyl group in the structure and (B) 0.02 to
An ink for ink jet recording comprising an alginate having a concentration of 0.5 weight percent (hereinafter, wt%), (C) 0.5 to 20 wt% of a wetting agent, (D) a penetrant, and (E) water. is there.

Further, the penetrant (D) is a surfactant having a critical micelle concentration (hereinafter cmc) or less in [I] ink, [II] 1 to 10 wt% of monohydric alcohol, [III].
It is an ink for ink jet recording characterized by being a single or a plurality of penetrants selected from derivatives of polyhydric alcohol in an amount of 0.5 to 5 wt%.

An ink for ink jet recording, characterized in that (F) a fluorine-containing surfactant is contained in the above ink.

A color ink jet recording method using at least two kinds of inks, wherein each ink contains at least the above components.

The inventors have found that the combined use of a dye having a carboxyl group in the structure and an alginate enhances the color developability and has a great effect on reducing bleeding. Generally, a recording ink using a dye having a carboxyl group in its structure is known to improve the water resistance of an image printed on a recording medium,
In the present invention, in addition to the improvement of water resistance, there is a synergistic effect in reducing bleeding due to the interaction between the carboxyl groups contained in the structures of both the alginate and the dye.

That is, it is known that alginate easily reacts with polyvalent metal cations such as calcium and aluminum in its aqueous solution, and gels and thickens.
It has been confirmed by the inventors' investigation that general plain paper contains monovalent cations such as sodium and polyvalent metal cations such as calcium and aluminum. The gelation reaction of alginate is promoted by the polyvalent metal cations eluted by the ink jetted on the plain paper, which contributes to sharpening of the dot shape, prevention of bleeding, and high color development.

The dye used in the present invention has a carboxyl group in its structure and is preferably used in the form of an alkali metal, ammonium salt or substituted ammonium salt. The dye may be black or color. Further, they may be used alone in the ink, or two or more kinds may be mixed and used.

As the alginate used in the present invention, specifically, Aldrich's reagent, duck algin (registered trademark of Kibun Food Chemifah Co., Ltd.) or the like can be used. The addition amount varies depending on the molecular weight, but the addition amount is 0.02-
Used in the range of 0.5 wt%.

Further, in order to reduce the color bleeding, the ink permeability is improved, and therefore the cmc
Although the addition of the above-mentioned surfactant is a general means, it is not necessary to increase the permeability in the present invention. When these penetrants are added to eliminate bleeding, a surfactant with a cmc or less, 1 to 10 wt%
The penetrability obtained with the monohydric alcohol of 0.5 to 5 wt% of the polyhydric alcohol derivative is sufficient.

As the above-mentioned surfactant, anionic,
Any of cationic, amphoteric, and nonionic can be used. Specifically, an alkyl sulfocarboxylate salt,
α-olefin sulfonate, polyoxyethylene alkyl ether acetate, N-acyl amino acid and its salt, N-acyl methyl taurine salt, alkyl sulfate polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate , Rosin acid soap,
Castor oil sulfate, lauryl alcohol sulfate, alkylphenol phosphate, alkyl phosphate, alkylallylsulfonate, diethylsulfosuccinate, diethylhexylsulfosuccinate, dioctylsulfosuccinate, and 2- There are vinyl pyridine attractants, poly 4-vinyl pyridine attractants, and the like.

Examples of the amphoteric surfactant include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine and other imidazolines. Derivatives and the like, further, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether Ether-based such as, polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distea Ester systems such as acid esters, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate, 2,4,7,9-tetramethyl- 5
-Decyne-4,7-diol, 3,6-dimethyl-4-
Octyne-3,6-diol, 3,5-dimethyl-1-
Acetylene glycols such as hexyne-3-ol (eg, Nisshin Chemical Surfinol 104, 82, 465,
485, TG, etc.). Of these, nonionic surfactants which are foamable and have good reliability are preferred, and acetylene glycol, ethylene oxide, and propylene oxide-added surfactants are particularly preferred.

If the amount of the surfactant added exceeds cmc, the permeability will remarkably increase, so it is necessary to use it at a concentration of cmc or less.

As the monohydric alcohol, monohydric alcohols having 1 to 4 carbon atoms such as methanol, ethanol and propanol are used. Desirable permeability is obtained in the range of 1-10 wt%. Here, the critical micelle concentration is the concentration at which the adsorption of the solution on the surface reaches saturation and the surface tension becomes a constant value.

As the polyhydric alcohol derivative, glycol ethers such as triethylene glycol monobutyl ether, propylene glycol monobutyl ether and dipropylene glycol monobutyl ether can be selected, and butyl ether is preferable. The addition amount is preferably in the range of 0.5 to 5 wt%.

On the other hand, the wetting agent is generally added to prevent clogging of the recording head, but it is common to use a water-soluble organic solvent, and ethylene glycol is generally used. , Diethylene glycol, triethylene glycol, 1,3-propanediol, 1,2,6-
Hexanetriol, polyhydric alcohols such as glycerin, ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, formamide, dimethylformamide,
Examples thereof include nitrogen-containing solvents such as 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidone and N-methyl-2-pyrrolidone, and sulfur-containing solvents such as thiodiglycol and dimethyl sulfoxide.

It is also possible to use a reagent (hereinafter referred to as a solid wetting agent) which is a powder or a crystalline solid at room temperature, has a high hygroscopic property, is easily soluble in ink or water, and has a function of being wettable by ink. it can.

As the solid wetting agent, urea, hydroxypropyl-β-cyclodextrin, trimethylolethane, trimethylolpropane, caprolactam, etc., as well as monosaccharides and polysaccharides such as sucrose and fructose can be used. .

These wetting agents may be used alone,
You may use 2 or more types together. Addition amount is 0.5-20w
A range of t% is preferable.

Further, the inventors have found that the ink containing the fluorine-containing surfactant spreads thinly and largely on the surface of the recording medium without deeply penetrating the paper. As a result, the amount of ejected ink can be suppressed, so that it is possible to shorten the drying time of the printed matter without imparting permeability to the ink.

The activator which satisfies these effects can be selected from the group consisting of fluorine-based compounds. Specifically, it is 100, 150 of Futergent (registered trademark of Neos Co., Ltd.),
251.

The components of the ink jet recording ink of the present invention are as described above, but other conventionally known water-soluble organic solvents, various dispersants, viscosity modifiers, optical brighteners and the like may be added as necessary. You can Examples of these are shown below. A water-soluble natural or synthetic polymer such as cellulose, polyvinylpyrrolidone, polyvinyl alcohol, and a water-soluble resin is used as a viscosity modifier, and the pH is adjusted by a buffer solution.
Examples thereof include regulators and fungicides.

Further, in order to prepare a recording liquid used in an ink jet recording method of the type in which the recording liquid is charged,
A specific resistance adjusting agent such as inorganic salts of lithium chloride, ammonium chloride and sodium chloride is added.

When applied to an ink jet recording method of the type in which a recording liquid is ejected by the action of heat energy, thermal physical property values (evaporation heat, boiling point, melting point, specific heat,
Thermal expansion coefficient, thermal conductivity, etc.) may be adjusted.

The ink jet recording ink of the present invention comprises
It is obtained by mixing and dissolving the above components and then filtering impurities and the like.

The physical properties of the ink are 50 in order to ensure stable ejection from the head and stable ink supply to the head.
It is preferably mPa · s or less, and more preferably 20 mPa · s or less.

[0037]

EXAMPLES The ink jet recording ink and the ink jet recording method of the present invention will be described below.

First, Table 1 shows examples of the present invention. All units of numerical values of composition ratio are weight percent concentration (wt%)
Is. Pure water is added so that the total amount becomes 100%.

[0039]

[Table 1]

Dye 1 having the composition shown in Table 1 is a compound represented by the structural formula (1).

[0041]

Embedded image

Dye 2 is a compound represented by the structural formula (2).

[0043]

Embedded image

Dye 3 is a compound represented by the structural formula (3).

[0045]

Embedded image

Dye 4 is a compound represented by the structural formula (4).

[0047]

[Chemical 4]

The compositions of the inks of Comparative Examples 1 to 5 are shown in Table 2.
Shown in

[0049]

[Table 2]

The following abbreviations are used in the compositions of Tables 1 and 2.

TEGmBE = triethylene glycol monobutyl ether Next, comparative examples of the present invention will be described.

Comparative Example 1 is an ink in which alginate is not added to the ink of Example 1. Comparative Example 2 is an ink obtained by adding no penetrant to the ink of Example 3. Comparative Example 3 is an ink using a dye having no carboxyl group in its structure. Comparative Example 4 is an ink containing a large amount of penetrant. Comparative Example 5 is an ink containing a large amount of alginate.

The components of the above ink are mixed and mixed at 60 ° C. for 2 hours.
After stirring for an hour, a 0.8 μm diameter membrane filter was used and pressure filtration was performed at a pressure of 2 kg / cm 2 to obtain an ink.

Ink jet recording has a discharge nozzle diameter of 30 μ.
m, piezoelectric element drive voltage 25 V, drive frequency 5.5 kHz
z, resolution 360 dots / inch, ink discharge rate 0.0
Using a prototype 48-nozzle inkjet evaluation machine adjusted to 5 μg, PPC paper (Xerox registered trademark PPC paper, Ricoh registered trademark RICOPY 6200), recycled paper (Honshu Paper registered trademark Yamayuri), bond paper (Meade registered trademark Gilbert Bond) The printing evaluation was performed using four types of fine paper (25% cotton paper) and fine paper (Oji Paper's registered trademark OK fine paper L).

The evaluation results are shown in Table 3.

[0056]

[Table 3]

Evaluation item Test 1 Bleed prevention effect in mixed color printing In Examples 1 and 2 and Comparative Example 1, printing around the character Bk was filled with YMC and RGB colors, and B was printed.
The k-letter bleed for each color was evaluated. The evaluation results are classified as follows.・ There is almost no difference in the printed state due to the paper, and bleeding or whiskers are not observed. ◎ ◎ The difference in the printed state due to the paper is slightly observed, but bleeding or whiskers are not noticeable. Bleeds and whiskers are observed depending on the paper ... △ ・ There are differences in the printing state depending on the paper, and bleeds and whiskers are observed on any paper ・ ・ ・ ×.

Test 2 Bleeding prevention effect in single color printing Character printing was performed and the printing quality was evaluated. The evaluation results are classified as follows. -There is almost no difference in print quality depending on the paper, and bleeding and whiskers are not observed. ◎ -Slight difference in print quality due to paper is seen, but bleeding and whiskers are not noticeable. Bleeding and whiskers are observed depending on the paper ... △ ・ There are differences in printing quality depending on the paper, and bleeding and whiskers are observed on any paper ・ ・ ・ ×.

Test 3 Improvement of print density The change in print density between the print obtained in Example 1 and Comparative Example 1 is shown as follows. The measurement was performed with a Macbeth spectrodensitometer. -The rate of change of the OD value improved by 5% or more ... ◎ -The rate of change of the OD value was within 5% ... O-The rate of change of the OD value decreased by 5% or more ... ×.

Test 4 Water resistance Character printing and solid pattern were printed on printing paper, left at room temperature for 24 hours, 0.5 ml of water was dropped on the printed part and naturally dried at room temperature, and the state of bleeding was visually observed. It was judged by.・ Bleeding is not conspicuous ・ ・ ・ ◎ ・ Slight bleeding ・ ・ ・ ○ ・ Character is slightly bleeding and solid is bleeding beyond the boundary of the pattern ・ ・ ・ △ ・ Character is unreadable and solid part Is missing ... ×.

Test 5 Fixability Evaluation Line printing was performed, and the print area was rubbed with a printing paper every 10 seconds to evaluate the fixability. The evaluation results are classified as follows.・ No rubbing after 10 seconds ・ ・ ・ ◎ ・ No rubbing after 20 seconds ・ ・ ・ ○ ・ No rubbing after 30 seconds ・ ・ ・ △ ・ Rubbing after 30 seconds or more ・ ・ ・ ×.

Test 6 Ejection Stability Evaluation The presence or absence of dot dropouts and ink splatters during continuous printing at room temperature is observed, and the time required until 10 or more occurrences is investigated. The evaluation results are classified as follows.・ 1 dot dropout or ink splatter for 48 hours or more
Do not occur 0 times ... ◎ ・ Dot omission or ink scattering 10 times within 24 to 48 hours ・ ・ ・ ○ ・ Dot omission or ink scattering 10 times within 1 to 24 hours・ ・ ・ △ ・ Dot dropout or ink scattering within 1 hour
Occurs 0 or more times ...

[0063]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an ink jet recording ink having high color development and high quality in color ink jet printing, no color bleeding in a color mixture, no single color bleeding, and further water resistance.

Claims (4)

[Claims] 1. A coloring agent (dye) having a carboxyl group in at least (A) structure, and (B) an alginate having a concentration of 0.02 to 0.5 weight percent (hereinafter referred to as wt%), (C) 0. An ink jet recording ink comprising 0.5 to 20 wt% of a wetting agent, (D) a penetrant, and (E) water. 2. The penetrant of (D) is a surfactant having a critical micelle concentration in the [I] ink or less, [II] 1 to 10 wt.
% Monohydric alcohol, [III] 0.5 to 5 wt% polyhydric alcohol derivative, and a single or plural penetrants. 3. The ink for ink jet recording according to claim 1, wherein the ink contains (F) a fluorine-based surfactant. 4. A color ink jet recording method using at least two kinds of inks, wherein each ink contains at least the above components.