JPH09302292A - Water-base ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-base ink composition which shows fixability equivalent to that of silver salt photography when it forms an image on a recording medium containing a dye accepting layer by using a fixation accelerator. SOLUTION: This composition forms an image on a recording medium containing a dye accepting layer, containing at least a dye and contains a fixation accelerator which accelerates the fixation of the dye on the layer. This accelerator is desirably a cyclic organic compound having at least one carbonyl group in the molecule and is exemplified by propylene carbonate or θ- butyrolactone. The content of the accelerator is desirably 0.5-50wt.% based on the composition. The composition is used for ink jet recording, writing utensils or general printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink composition used for applications such as ink jet recording, writing instruments, and general printing, and particularly suitable for a recording medium having a dye receiving layer. Regarding things.

[0002]

2. Description of the Related Art An on-demand type ink jet recording printer is a printer that ejects ink droplets from a nozzle in accordance with a control signal and deposits the droplets on a recording medium such as paper or OHP film. It has become popular rapidly in recent years due to the possibility of cost reduction. The method of ejecting ink droplets from the nozzle is roughly classified into a method in which the ink is pressurized by the displacement of a piezo element, and a method in which the ink in the nozzle is heated and vaporized by a heating element and the pressure of generated bubbles is used. You. Both methods have advantages such as low noise, image formation on plain paper, low running cost, and no waste such as ink ribbons and toner cartridges. For this reason, ink jet recording apparatuses are rapidly spreading for both office use and home use.

Characters and images formed by this ink jet recording method have a problem that, in principle, it is impossible to obtain semi-permanent fixing property as in silver halide photography. That is, in a general inkjet recording ink, a water-soluble direct dye is used, and according to the dyeing theory,
After the direct dye is transferred to the dye receiving layer, it is held in a state of being adsorbed to the dye receiving layer by the interaction such as van der Waals force or hydrogen bond between the two. Therefore,
When the recording medium on which an image has been formed is directly contacted with a solvent, resin, or the like having a higher affinity with the dye, or when heat energy or the like which exceeds the interaction force is externally applied, the dye receiving layer may cause other problems. Direct dye transfer to or out of the material occurs. As a result, this phenomenon appears as image blurring, blurring, and fading.

As a conventional technique for preventing such image deterioration, a dye receiving layer such as an intercalation compound is contained in a recording medium, and an intercalation by ion exchange with a basic dye or the like in an aqueous ink composition is carried out. A method of fixing and holding a dye by utilizing a cation reaction has been proposed.

[0005]

In the above-mentioned prior art, even if ink droplets ejected from the printer head fly to the recording medium, the ink may not be completely penetrated into the dye receiving layer and the drying may be finished. . In this case, a dye that cannot completely react with the intercalation compound remains, and this residual dye is not fixed. Further, when the reactivity between the dye and the intercalation compound is low, there is a problem that it takes a long time to form a stable image. The present invention proposes to solve such a problem. That is, an object of the present invention is to provide a water-based ink composition exhibiting fixability comparable to that of a silver salt photograph when forming an image on a recording medium containing a dye receiving layer.

[0006]

The water-based ink composition of the present invention is proposed to solve the above-mentioned problems and contains at least a dye which forms an image on a recording medium containing a dye-receiving layer. A water-based ink composition comprising: a fixing accelerator which accelerates the fixing property of the dye to the dye receiving layer. In a preferred embodiment of the present invention, the fixing accelerator can be exemplified by a cyclic organic compound having at least one carbonyl group in the molecule. The content of the fixing accelerator is preferably 0.5% by weight or more and 50% by weight or less, and more preferably 1% by weight 30% by weight or less with respect to the aqueous ink composition.

In order to secure the fixing property of the water-based ink composition, the inventors of the present invention are not sufficient in only the technique of including a dye receiving layer such as an intercalation compound in the recording medium, and promote the fixing. It has been found that the addition of a fixing accelerator is effective. Further, as the fixing accelerator, a cyclic organic compound having at least one or more carboxyl groups in the molecule is
The present invention has been completed by finding that it enables quick and uniform fixing and particularly improves water resistance. The cyclic organic compound having at least one carboxyl group in the molecule is not particularly limited, but for example, propylene carbonate (C ₄ H ₆ O ₃ , bp = 238 to 239 ° C.), γ
Butyrolactone (C ₄ H ₆ O ₂ , bp = 204 ° C.) and the like are exemplified. The cyclic compound having at least one carboxyl group in the molecule has a small fixing effect at a content of less than 0.5% by weight with respect to the aqueous ink composition, and has a drying property at a content of more than 50% by weight. Is reduced, etc.
The content of 0.5% by weight or more and 50% by weight or less, particularly 1% by weight or more and 30% by weight or less is preferable because it affects other physical properties of the ink.

[0008]

EXAMPLES Hereinafter, the present invention will be described in detail by taking a water-based ink composition for inkjet recording as an example.

Example 1 In this example, propylene carbonate (propylene carbonate) was adopted as a cyclic organic compound having at least one carboxyl group in the molecule, and its fixing property was examined.

Preparation of Recording Medium 4 g of polyvinyl alcohol as a binder was added and dissolved in a mixed solvent of 64 g of ethyl alcohol and 14 g of water. 16 g of organic acid-treated hydrotalcite as a dye receiving layer was added to this solution, and the mixture was dispersed for 8 hours by a bead mill to obtain a dispersion liquid. Malic acid was adopted as the organic acid, and hydrotalcite was used after adsorption treatment with 10 mg of malic acid. The obtained dispersion was applied on a transparent polyester film (125 μm thick Lumirror T-60, manufactured by Toray Industries, Inc.) with a wire bar and dried at 100 ° C. for 1 minute to obtain a recording medium. The coating thickness was 6 μm after drying.

84 g of adjusted water for the aqueous ink composition and diethylene glycol monomethyl ether 1
3 g of water-soluble dye C-319H (trade name of Daiwa Kasei Co., Ltd.) was dissolved in a mixed solution of 0 g and 2-pyrrolidone 3 g to obtain 100 g of an aqueous ink composition A0. This aqueous ink composition A0 is a comparative sample containing no propylene carbonate. Similarly, a predetermined amount of water, 10 g of diethylene glycol monomethyl ether, 3 g of 2-pyrrolidone, and 3 g, 5 g, and 7 g of propylene carbonate.
Then, 3 g of the water-soluble dye C-319H (trade name of Daiwa Kasei Co., Ltd.) was dissolved in the mixed solution containing 10 g of each to obtain 100 g of the aqueous ink compositions A1 to A4. That is, water has a total weight of the aqueous ink composition of 100.
A predetermined amount was selected to be g.

Evaluation of Water Resistance A test pattern image was formed on the above-described recording medium by using the five kinds of aqueous ink compositions A0 to A4 thus obtained. The inkjet recording device is HP-120.
0C (HP Co., Ltd.) was used. Each test pattern image was dried at room temperature for 1 hour, the high-density portion (solid printed portion) of the test pattern image was immersed in water for 10 minutes, and then sufficiently dried at room temperature again to obtain a water resistance test sample. The image density of this water resistance test sample was measured using a Macbeth densitometer TR-924, and the results in Table 1 were obtained.

[0013]

[Table 1]

As is clear from Table 1, the concentrations after the water resistance test have a relationship of A0 <A1 <A2 <A3 <A4, and the water resistance is remarkably improved by the addition of propylene carbonate, and the content of propylene carbonate is 1% by weight
In the range of 10 to 10% by weight, it is clear that the higher the content, the less the flow-out of the image and the like, and the faster the fixing of the dye.

Example 2 In this example, γ-butyrolactone was adopted as a cyclic organic compound having at least one carboxyl group in the molecule, and its fixing property was examined.

A predetermined amount of water for preparation of the water- based ink composition, 10 g of diethylene glycol monomethyl ether, 3 g of 2-pyrrolidone, and 2 g, 5 g, 10 g and 20 g of γ-butyrolactone are added respectively in a mixed solution to obtain water solubility. 3 g of Dye C-319H (trade name of Daiwa Kasei Co., Ltd.) was dissolved to obtain 100 g of the aqueous ink compositions B1 to B4. That is, a predetermined amount of water was selected so that the weight of the aqueous ink composition was 100 g.

Water resistance evaluation B1 to B4 thus obtained and the above-mentioned comparative example A
A water resistance test was carried out in the same manner as in Example 1 using 5 kinds of water-based ink compositions of No. 0, and the results in Table 2 were obtained.

[0018]

[Table 2]

As is clear from Table 2, the concentrations after the water resistance test are in the relationship of A0 <B1 <B2 <B3 <B4, and the water resistance is remarkably improved by the addition of γ-butyrolactone, and the concentration of γ-butyrolactone is improved. When the content is in the range of 2% by weight to 20% by weight, it is apparent that the higher the content, the less the flow-out of the image and the like, and the faster the fixing of the dye.

Comparative Example 1 This comparative example does not contain a cyclic organic compound having at least one or more carboxyl groups in the molecule, but instead uses ethylene glycol (C ₂ H ₆ ) as a usual polyhydric alcohol.
The fixing property of the aqueous ink composition containing O ₂ and bp = 197.6 ° C.) was examined.

A water-soluble dye is added to a mixed solution prepared by adding a predetermined amount of adjusted water of the aqueous ink composition, 10 g of diethylene glycol monomethyl ether, 3 g of 2-pyrrolidone, and 2 g, 5 g, 7 g and 10 g of ethylene glycol, respectively. C-319H (Daiwa Kasei Co., Ltd.
3 g of the product name) was dissolved to obtain 100 g of the aqueous ink compositions C1 to C4. That is, a predetermined amount of water was selected so that the weight of the aqueous ink composition was 100 g.

Water resistance evaluation C1 to C4 thus obtained and the above-mentioned comparative example A
A water resistance test was carried out in the same manner as in Example 1 using 5 kinds of water-based ink compositions of No. 0, and the results in Table 3 were obtained.

[0023]

[Table 3]

As is clear from Table 3, the concentration after the water resistance test has a relationship of C4 <C3 <C2 <C1≈A0, and the addition of a small amount of ethylene glycol slightly improves the water resistance but promotes fixing. It can be seen that the effect is weak, and in the range of 5% by weight or more, the higher the content, the more the image flow occurs, which hinders the fixing of the dye.

Comparative Example 2 This comparative example does not contain a cyclic organic compound having at least one or more carboxyl groups in the molecule, but instead uses propylene glycol (C ₃ H) as a usual polyhydric alcohol.
₈ O ₂ , bp = 188.2 ° C.) was added to the aqueous ink composition, and its fixing property was examined.

A water-soluble dye was added to a mixed solution prepared by adding a predetermined amount of prepared water of the aqueous ink composition, 10 g of diethylene glycol monomethyl ether, 3 g of 2-pyrrolidone, and 2 g, 5 g, 10 g and 20 g of propylene glycol. 3 g of C-319H (trade name of Daiwa Kasei Co., Ltd.) was dissolved to obtain 100 g of aqueous ink compositions D1 to D4. That is, a predetermined amount of water was selected so that the weight of the aqueous ink composition was 100 g.

Water resistance evaluation D1 to D4 thus obtained and the comparative example A above.
A water resistance test was carried out in the same manner as in Example 1 using 5 kinds of aqueous ink compositions of No. 0, and the results in Table 4 were obtained.

[0028]

[Table 4]

As is clear from Table 4, the concentrations after the water resistance test have a relationship of D4 <D3 <A0 <D2 <D1. Although the water resistance is slightly improved by adding a small amount of propylene glycol, the effect of promoting fixing is not improved. What you can not expect much,
On the other hand, in the range of 10% by weight or more, it is found that the flow of the image occurs more than that of the comparative example, which hinders the fixing of the dye.

Comparative Example 3 In this comparative example, an aqueous ink containing no cyclic organic compound having at least one or more carboxyl groups in the molecule and instead adding polyethylene glycol (molecular weight 300) as a normal polyhydric alcohol. The composition was examined for its fixability.

A water-soluble dye was added to a mixed solution prepared by adding a predetermined amount of adjusted water of the aqueous ink composition , diethylene glycol monomethyl ether (10 g), 2-pyrrolidone (3 g), and polyethylene glycol (2 g, 5 g, 10 g, and 20 g), respectively. 3 g of C-319H (trade name of Daiwa Kasei Co., Ltd.) was dissolved to obtain 100 g of aqueous ink compositions E1 to E4. That is, a predetermined amount of water was selected so that the weight of the aqueous ink composition was 100 g.

Evaluation of Water Resistance E1 to E4 thus obtained and Comparative Example A above
A water resistance test was conducted in the same manner as in Example 1 using the five types of water-based ink compositions of No. 0, and the results in Table 5 were obtained.

[0033]

[Table 5]

As is clear from Table 5, the concentrations after the water resistance test are in the relationship of E4 <E3 <E2 <E1≈A0, and the addition of a small amount of ethylene glycol slightly improves the water resistance but promotes fixing. It can be seen that the effect is weak, and in the range of 5% by weight or more, the higher the content, the more the flow of the image occurs, which rather hinders the fixing of the dye.

Although the preferred embodiments of the present invention have been described in detail above, the present invention can be embodied in various modes other than these embodiments. For example, propylene glycol and γ-butyrolactone have been exemplified as the cyclic compound having at least one carboxyl group in the molecule, but various carboxyl group-containing cyclic compounds may be used in addition to this material. The addition of other fixing accelerators is also useful.
Although the ink jet recording ink has been exemplified as the water-based ink composition, it can be suitably used for various printing inks and writing instrument inks. Further, although the polyester film is exemplified as the recording medium, it may be a paper medium including a usual dye receiving layer.

[0036]

As is clear from the above description, according to the aqueous ink composition of the present invention, recording having a dye receiving layer by adding a cyclic compound having at least one carboxyl group in the molecule. It is possible to remarkably improve the fixability of the image formed on the medium, and it is possible to provide the reliability comparable to that of a silver salt photograph.

Claims (3)

[Claims] 1. An aqueous ink composition containing at least a dye for forming an image on a recording medium having a dye receiving layer, which comprises a fixing accelerator for promoting the fixing property of the dye to the dye receiving layer. A water-based ink composition comprising: 2. The aqueous ink composition according to claim 1, wherein the fixing accelerator is a cyclic organic compound having at least one carbonyl group in the molecule. 3. The aqueous ink composition according to claim 1, wherein the content of the fixing accelerator is 0.5% by weight or more and 50% by weight or less based on the aqueous ink composition.