JP2001011345A - Ink composition for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition which satisfies all of the characteristics of securing high-quality images and high color concentrations on common paper, and resistance to light and wafer by combining specific dyes in a specific weight ratio range. SOLUTION: This composition contains (A) carbon black and (B) a dye shown by formula I [M is a cation selected from the group consisting of H, and groups of an alkali metal, ammonia and organic amine; and (m) is 1 or 2 and (n) is 0 or 1], preferably in a component A/component B weight ratio of (2.5:1) to (7:1). It is preferable that the composition contains (C) 7 to 12 wt.% of a lower alkyl ether of a polyhydric alcohol, in particular monobutyl ether of triethylene glycol and (D) 0.5 to 1.2 wt.% of an acetylene glycol shown by formula II [R1 to R4 are each a 1-6C alkyl; and (n+m) is 0 to 30], to keep surface tension of the compound at 20 to 40 mN/m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a high quality image and image on plain paper.
The present invention relates to an ink-jet recording ink which has a high color density and is excellent in light resistance and water resistance.

BACKGROUND ART [0002] Ink jet recording methods include:
This is a printing method in which small droplets of the ink composition fly and adhere to a recording medium such as paper to perform printing. This method has a feature that high-resolution and high-quality images can be printed at a high speed with a relatively inexpensive device. Generally, an ink composition used for ink jet recording mainly contains water, and further contains a coloring component of a dye or a pigment and a wetting agent such as glycerin for the purpose of preventing clogging.

In an ink jet printer, to make the printer more versatile,
Water resistance and light resistance of printed matter are required. JP-A-5-140495 proposes an ink composition containing pyrrolidone (refers to 2-pyrrolidone, N- (2-hydroxyethyl) -2-pyrrolidone or a mixture thereof) in order to improve the water resistance of printed matter. Have been. Further, U.S. Pat. No. 4,963,189 and U.S. Pat.
No. 12 discloses a dye which has the property of being readily soluble in bases while not soluble in neutral water.

However, although the water resistance has been improved to some extent, it is still unsatisfactory, and the light resistance is also at an insufficient level.

Therefore, it is widely considered to use a pigment as a coloring material in order to satisfy both water resistance and light resistance. However, pigments generally have lower color development and lower optical density than dyes.

Further, as a recent trend, in order to realize high-speed printing, it is necessary to quickly fix ink. Therefore, attempts have been made to improve the permeability of the ink into the recording medium. For example, Japanese Patent Application Laid-Open No. 4-1
No. 8,3761, U.S. Pat. No. 5,156,675, and U.S. Pat. No. 5,183,502 include the addition of diethylene glycol monobutyl ether and the addition of both glycol ethers and a nonionic acetylene glycol-based surfactant. It has been disclosed.

However, in the case of the penetrating ink using the pigment, the coloring property is further degraded by improving the penetrating property, and in particular, plain paper whose surface is not specially processed (used in offices, schools and homes). Optical paper tended to be significantly lower than that of copy paper, report paper, bond paper, stationery, postcards, and slip paper.

[0008]

SUMMARY OF THE INVENTION The present inventors have now concluded that a high-quality image / high color density can be obtained by combining a pigment and a specific dye as colorants in a specific weight ratio range. It has been found that an image having excellent properties can be obtained. More specifically, by combining carbon black and a specific black dye at a specific weight ratio, a high-quality image (clear image without bleeding or whiskers) and high color density can be realized even on plain paper, Fixing of ink, water resistance of printed matter,
It has been found that an ink composition giving light fastness can be realized.

Accordingly, an object of the present invention is to provide an ink composition which can satisfy all characteristics such as high-quality images, high color density, light fastness and water fastness on plain paper.

The ink jet recording ink of the present invention is an ink composition comprising carbon black and a dye represented by the following formula (I), and is represented by carbon black and a formula (I). The weight ratio of the dye is 2.5: 1 to 1
7 to 12% by weight of a polyhydric alcohol lower alkyl ether, and 0.5 to 1.2% by weight of an acetylene glycol of the following formula (II).
An ink composition comprising:

Embedded image [In the formula, M represents a cation of a group selected from the group consisting of a hydrogen atom, an alkali metal, ammonia, and organic amines, m represents 1 or 2, and n represents 0 or 1.]

Embedded image [Wherein, R ¹ , R ² , R ³ , and R ⁴ each independently represent a C _1-6 alkyl group, and n + m represents 0 to 30. ]

[0011]

DETAILED DESCRIPTION OF THE INVENTION [Ink composition] The ink jet recording ink used in the present invention basically comprises carbon black, a specific dye, a polyhydric alcohol lower alkyl ether, acetylene glycol and water. is there.

[Coloring Material] In the present invention, by combining carbon black and a specific black dye in a specific weight ratio range, it is possible to obtain a printed matter having excellent print quality, high color density, and excellent water resistance and light resistance. Realization has become possible.

The carbon black (CI Pigment Black 7) used in the present invention includes furnace black, lamp black, acetylene black, and the like.
Channel black and others.

According to a preferred embodiment of the present invention, these pigments are preferably added to the ink as a pigment dispersion obtained by dispersing the pigment in an aqueous medium with a dispersant. As a preferred dispersant, a dispersant commonly used for preparing a pigment dispersion, for example, a polymer dispersant or a surfactant can be used.

The amount of the pigment added to the ink composition is 0.1
About 15% by weight, more preferably 2 to 10% by weight.
% By weight.

The specific black dye is a dye represented by the formula (I). Even if this dye is used alone, its water resistance is relatively good, so that when it is mixed with a pigment at a specific weight ratio, the water resistance is hardly impaired. In addition, since this dye has a high color development, it is possible to obtain high-density printing even if the total amount of coloring materials is small.

The abundance ratio of carbon black and the dye represented by formula (I) in the ink composition may be appropriately determined in the range where the above advantages and light resistance and high printing quality can be obtained. And a dye represented by the formula (I) in a weight ratio of 2.5: 1 to 7: 1, more preferably 3: 1 to 5: 1.

The dye represented by the formula (I) used in the present invention is a known dye described in US Pat. No. 4,963,189 and US Pat. No. 5,203,912.

As described above, the dye represented by the formula (I) is described in US Pat. No. 4,963,189 and US Pat.
Since it is described in the specification of JP-A-203912, it can be produced with reference to those descriptions. Also, JP-A-2-140270, Color Index Third Edition (Color Index, Third Ed)
ition, The society of Dyes a
nd Colorists). Specifically, the dye represented by the formula (I) is preferably a dye represented by the following formula (V) and / or (VI).

Embedded image

The dye represented by the above formula (I) is disclosed in JP-B-5-80956 or JP-A-5-262998.
, Japanese Patent Laid-Open No. 5-125318, U.S. Pat.
As is known in, for example, JP-A-96-189189, the added ink composition is required to be basic for dissolution. Therefore, also in the ink composition according to the present invention,
Preferably, the pH is adjusted to basic. According to a preferred embodiment of the present invention, the pH of the ink composition is 8.
It is preferably in the range of 5 to 11, more preferably 8.5 to 10.

Examples of the pH adjuster include potassium hydroxide, sodium hydroxide, triethanolamine and the like.

[Aqueous solvent] According to a preferred embodiment of the present invention, the ink composition contains a polyhydric alcohol lower alkyl ether.

Preferred specific examples of polyhydric alcohol lower alkyl ethers include mono-, di- and triethylene glycol C _1-6 alkyl ethers, mono-, di- and tripropylene glycol C _1-6 alkyl ethers, and more preferably triethylene glycol. Examples thereof include monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, and propylene glycol monobutyl ether. Most preferred is triethylene glycol monobutyl ether.

This amount is preferably 7 to 12% by weight, more preferably 7 to 10% by weight.

Further, the ink composition according to the embodiment of the present invention comprises acetylene glycol represented by the above formula (II). Preferred specific examples of acetylene glycol are shown in the following table.

[0026]

[Table 1] No. in the table. One acetylene glycol is most preferred. As these acetylene glycols, commercially available ones can be used. For example, Surfynol 440, 465, 82 and TG (manufacturer: Air Produc)
t and Chemicals, Inc., sold by Shin-Etsu Chemical Co., Ltd.).

The amount of acetylene glycol added is 0.5 to
It is preferably 1.2% by weight, more preferably 0.1% by weight.
5 to 1% by weight.

By using the lower alkyl ether of polyhydric alcohol and acetylene glycol in the above-mentioned amounts in combination, the quick drying property of the ink composition can be improved, and the deterioration of print quality due to bleeding or color mixing can be prevented. Furthermore, when a polyhydric alcohol lower alkyl ether is used alone, a phenomenon that the resin constituting the recording head and the ink flow path is eroded is often observed, but in combination with acetylene glycol, A severe erosion phenomenon can also be prevented. Furthermore, the effect can be further improved by adding a hydrophilic high-boiling point low-volatile solvent described later to the polyhydric alcohol lower alkyl ether in an amount of 50% by weight or more.

Further, in the case of color printing, the quality of a color image is degraded if dots flow out and color mixing or the like occurs between adjacent dots. According to the combination of polyhydric alcohol lower alkyl ether and acetylene glycol, such color mixing can be prevented, and a high-quality color image can be realized.

According to a preferred embodiment of the present invention, the ink composition preferably contains an organic solvent. The organic solvent is preferably a low-boiling organic solvent, and preferred examples thereof include methanol, ethanol, n-propyl alcohol, iso-butanol, n-butanol, sec-butanol, tert-butanol, iso-butanol, and n-butanol. −
Pentanol, and the like. Particularly, a monohydric alcohol is preferable. The low-boiling organic solvent has the effect of shortening the drying time of the ink.

Examples of the hydrophilic high-boiling low-volatile solvent used in the present invention include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol and polypropylene glycol. Low-volatile polyhydric alcohols are used, and N-methyl-2-pyrrolidone, 1, 3
-Dimethylimidazolidinone, monoethanolamine,
A range in which a water-soluble organic solvent such as a nitrogen-containing organic solvent such as N, N-dimethylethanolamine, N, N-diethylethanolamine, Nn-butyldiethanolamine, triisopropanolamine, and triethanolamine does not cause printing bleeding. Can be added. Particularly, diethylene glycol, glycerin and the like are preferable. It is well known that these hydrophilic high-boiling low-volatile solvents are added as humectants to prevent clogging and the like, but the greatest effect as an essential component of the present invention is to reduce the erosion of members. is there. Particularly, when a volatile component such as water evaporates in the head or in the ink supply path due to occurrence of an abnormal situation due to a failure of the printing apparatus, etc., the member erosion of the polyhydric alcohol lower alkyl ether is reduced.

The amount of the humectant added is 0.5% of the ink.
About 40% by weight, more preferably 2 to 20% by weight.
% By weight. The amount of the low-boiling organic solvent added is preferably about 0.5 to 10% by weight, more preferably 1.5 to 6% by weight of the ink.

In addition, a pH adjuster, a preservative, a fungicide and the like may be added as necessary.

When the ink composition according to the present invention is used in an ink jet recording method, good responsiveness, discharge stability,
In order to realize appropriate dot spread and good roundness, the viscosity of the ink composition is preferably 30 mPa · s or less at an operating temperature of 0 to 50 ° C., more preferably 1.2 to 20 mPa · s. s, and the surface tension of the ink composition is 2 at an operating temperature of 0 to 50 ° C.
It is preferably about 0 to 40 mN / m.

[0035]

The present invention will be described in more detail with reference to the following examples, but it should not be construed that the invention is limited thereto.

The following ink composition was prepared according to a conventional method. That is, the ink composition was prepared by dispersing carbon black together with a dispersant component, adding and mixing a dye and other components, and filtering an insoluble component having a size equal to or larger than a predetermined size to obtain an ink composition.

Example 1 Carbon black MA7 2.5% by weight (manufactured by Mitsubishi Chemical Corporation) Dye represented by formula (VI) 1.0% by weight Styrene-acrylic copolymer / ammonium salt 1.5% by weight (molecular weight 7000) : Dispersant) Glycerin 10 wt% Surfynol 465 1 wt% Triethylene glycol monobutyl ether 7 wt% Proxel XL2 0.3 wt% (Preservative: manufactured by ZENECA) Ion exchange water

Example 2 Carbon black MA7 2.5 wt% (manufactured by Mitsubishi Chemical Corporation) Dye represented by formula (VI) 0.5 wt% Styrene-acrylic copolymer / ammonium salt 1.5 wt% (molecular weight 7000) : Dispersant) Glycerin 10 wt% Surfynol 465 1 wt% Triethylene glycol monobutyl ether 7 wt% Proxel XL2 0.3 wt% (Preservative: manufactured by ZENECA) Ion exchange water

Example 3 3.5% by weight of carbon black Raven1080 (manufactured by Colombian Carbon) 0.5% by weight of dye represented by formula (VI): 1.5% by weight of styrene-acrylic copolymer / ammonium salt (molecular weight: 7000: dispersion Glycerin 10 wt% Surfynol 465 1 wt% Triethylene glycol monobutyl ether 7 wt% Proxel XL2 0.3 wt% (Preservative: manufactured by ZENECA) Ion-exchanged water

Example 4 Carbon black MA7 4.0 wt% (manufactured by Mitsubishi Chemical Corporation) Dye represented by formula (VI) 2.0 wt% Styrene-acrylic copolymer / ammonium salt 0.5 wt% (molecular weight 7000) : Dispersant) Glycerin 10 wt% Surfynol 465 1 wt% Triethylene glycol monobutyl ether 7 wt% Proxel XL2 0.3 wt% (Preservative: manufactured by ZENECA) Ion exchange water

Comparative Example 1 Carbon black MA7 3.5 wt% (manufactured by Mitsubishi Chemical Corporation) Styrene-acrylic copolymer / ammonium salt 1.5 wt% (molecular weight 7000: dispersant) Glycerin 10 wt% Surfynol 465 1 wt% Tri Ethylene glycol monobutyl ether 7wt% Proxel XL2 0.3wt% (preservative: manufactured by ZENECA) Ion exchange water

Comparative Example 2 Dye represented by Formula (VI) 3.5 wt% Glycerin 10 wt% Surfynol 465 1 wt% Triethylene glycol monobutyl ether 7 wt% Proxel XL2 0.3 wt% (Antiseptic: manufactured by ZENECA) Ion exchange Water remaining

The surface tension of the above ink composition (mN /
m) was as follows.

[Printing Evaluation Test] The following printing evaluation test was performed.
Using an inkjet printer MJ-930C (trade name: manufactured by Seiko Epson Corporation), a resolution of 720 dp was used.
i (dot / inch) and the ink ejection amount was 20 ng / dot. The following six types of paper were used for evaluation.

Evaluation paper Xerox P (Xerox Corporation) Ricopy 6200 (Ricoh Corporation) Xerox 4024 3R 721 (Xerox Corporation) Neenah Bond (Kimberly Clark Corporation) Xerox R (Xerox Corporation) )) Yamayuri (Honshu Paper Co., Ltd.)

Evaluation 1: Print Quality The above-mentioned recording paper was subjected to alphabet printing, and the presence or absence of bleeding and whiskers was visually observed.
The results were evaluated according to the following criteria. A: Bleeding was observed on all papers, and hardly any beard was observed. B: Bleeding and beard were slightly recognized on some papers. C: Depending on the paper, bleeding and beard were observed. NG: Bleeding and whiskers were observed on all papers.

Evaluation 2: OD value Graphic printing was performed on all the recording papers described above, and the optical density (OD value) of the solid portion was measured. The average value of the OD values of the six papers was evaluated according to the following criteria. In addition, in the OD value measurement,
The reflection density was measured using Macbeth TR-927 manufactured by Macbeth. A: The average OD value is 1.30 or more. B: The average OD value is 1.20 or more and less than 1.30. C: Average OD value is 1.10 or more and less than 1.20. NG: The average OD value is less than 1.10.

Evaluation 3: Water Resistance Alphabet printing was performed on all of the above recording papers. The printed sample was completely immersed in water for 5 minutes, allowed to air dry, the state of the sample was visually observed, and the results were evaluated according to the following criteria. A: No change from the initial state in all papers. B: Characters are difficult to read on some papers. C: Characters are difficult to read on most papers. NG: Characters cannot be read on most papers.

Evaluation 4: Light fastness Solid printing was performed on the paper described above, and this was subjected to a light fastness acceleration test under the following conditions, and evaluated according to the following evaluation criteria.

[Test conditions] Xenon weatherometer C
i35A (ATLAS) and black panel 6
3 ° C., 50% relative humidity, irradiance with UV light at 340 nm
Exposure was performed at 35 W / m ² and an irradiation time of 500 hr.

[Evaluation Criteria] Spectrophotometer GRETAG S
The reflection density was measured using PM (GRETAG). Light source D50 No light source filter White standard absolute white Viewing angle 2 ° Density residual rate A: Exceeds 90%. B: 80% or more and less than 90%. NG: less than 80%.

The evaluation results were as shown in Table 2 below.

[Table 2]

Claims (6)

[Claims] 1. An ink composition for inkjet recording comprising carbon black and a dye, wherein the dye is a dye represented by the following formula (I). Embedded image [In the above formula, M represents a cation of a group selected from the group consisting of a hydrogen atom, an alkali metal, ammonia, and organic amines, m represents 1 or 2, and n represents 0 or 1.] 2. The ink composition according to claim 1, wherein the weight ratio of the carbon black to the dye represented by the formula (I) is in the range of 2.5: 1 to 7: 1. 3. A polyhydric alcohol lower alkyl ether comprising 7
3. The ink composition according to claim 1, wherein the ink composition comprises about 12% by weight and 0.5 to 1.2% by weight of acetylene glycol represented by the following formula (II). Embedded image [Where R ¹ , R ² , R ³ , and R ⁴ each independently represent a C _1-6 alkyl group, and n + m represents 0 to 30] 4. The lower alkyl ether of a polyhydric alcohol is triethylene glycol monobutyl ether, and the acetylene glycol is represented by the formula (II) wherein R ¹ and R ⁴ are
iso-butyl, R ² and R ³ are methyl groups,
4. The ink composition according to claim 1, wherein m + n is about 10. 5. The ink composition according to claim 1, which has a surface tension of 20 to 40 mN / m. 6. The ink according to claim 1, wherein the dye represented by the formula (I) is a dye represented by the following formulas (V) and / or (VI). Composition. Embedded image