JP2009046608A - Ink composition, ink set, inkjet-recording method and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition and an ink set capable of producing a recorded matter excellent in moisture resistance and to provide an inkjet-recording method and to provide the recorded matter. <P>SOLUTION: The present invention provides an ink composition containing at least gelatin having ≤215 g jelly strength, having ≤0.8 wt.% gelatin content and being alkali-treated and an ink set containing the ink composition and an inkjet-recording method using the ink set and a recorded matter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink composition, an ink set including the ink composition, an ink jet recording method using the ink set, and a recorded matter, and in particular, an ink composition capable of improving the moisture resistance of an obtained image, The present invention relates to an ink set using an ink composition having such characteristics as one of the constituent components, an ink jet recording method using the ink set, and a recorded matter obtained by the recording method.

  The ink jet recording method is a printing method in which printing is performed by ejecting small droplets of ink from a fine nozzle head so that the ink droplets are ejected and adhered to a recording medium such as paper. This method is characterized in that a high-resolution and high-quality image can be printed at a high speed with a relatively inexpensive apparatus. Ink jet recording apparatuses using this method are widely accepted commercially due to good print quality, low cost, relatively quiet operation and graphic forming ability. Among them, thermal (Bubble Jet®) and piezoelectric drop-on-demand printers have been particularly successful in the market and have been widely used as printers for personal computers in offices and homes.

  As inks used in the ink jet recording method, for example, inks in which a dye, which is a coloring material, is dissolved in an aqueous medium, or pigments dispersed in an aqueous solvent with a surfactant or a polymer dispersant have been proposed as inks. Yes. Recently, a plurality of color ink compositions are prepared as an ink set, and a color image is formed by ink jet recording. In general, a color image is formed by four colors including a yellow ink composition, a magenta ink composition, and a cyan ink composition, and optionally a black ink composition. Further, color images may be formed with six colors obtained by adding a light cyan ink composition and a light magenta ink composition to these four colors, or seven colors obtained by further adding a dark yellow ink composition.

In recent years, photographic image quality printing by a color ink jet printer has become inferior to silver salt photographs due to continuous improvement of the head, ink composition, recording method, and media, and the image quality is comparable to that of photographs.
On the other hand, with respect to the storability of the obtained image, the characteristics are improved by improving the ink composition and the media. In particular, with respect to improvement of moisture resistance, many proposals have been made in the past, including, for example, a proposal using a specific color material and an amino acid in combination (see Patent Document 1, etc.).

JP 2006-83339 A

  The present invention has been made in consideration of the above-mentioned circumstances regarding the ink composition used in the ink jet recording method, and an ink composition capable of improving the moisture resistance of the obtained image and the ink composition. It is an object of the present invention to provide an ink set containing the ink set, an ink jet recording method using the ink set having such characteristics, and a recorded matter obtained by the recording method.

  The present inventors printed a large number of ink compositions comprising combinations of various dyes (hereinafter also referred to as color materials) useful as a color material of the ink composition and various additives on a recording medium by an ink jet recording method. As a result of diligent investigation on the moisture resistance on the recording medium, the ink composition containing at least gelatin having a jelly strength within a specific value range as an essential component is printed on the recording medium alone. Of course, the present inventors have obtained knowledge that sufficient moisture resistance can be exhibited when color mixing with dyes other than the above is performed.

The present invention has been made on the basis of such knowledge, and provides the following inventions. [1] An ink composition comprising at least gelatin having a jelly strength of 215 g or less as an essential component, and the gelatin content being 0.8% by weight or less;
[2] The ink composition according to [1], wherein the gelatin is alkali-treated gelatin;
[3] An ink set comprising the ink composition according to [1] or [2];
[4] An ink jet recording method using the ink set according to [3];
[5] A recorded matter obtained by the ink jet recording method according to [4].

  According to the present invention, the moisture resistance of the obtained image can be improved.

  Next, an embodiment of the present invention will be described. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. The present invention can be implemented in various forms without departing from the gist thereof.

The ink composition of the present invention contains at least gelatin having a jelly strength of 215 g or less as an essential component, and the gelatin content is 0.8% by weight or less.
The ink composition of the present invention contains the gelatin having a jelly strength of 215 g or less as an essential component, so that the moisture resistance required for the recorded material can be imparted without depending on the moisture resistance ability of the paper.

  In the present invention, “jelly strength of 215 g or less” means that the jelly strength defined in JIS K6503 is 215 g or less.

  In the present invention, by setting the gelatin content to 0.8% by weight or less, there is an effect that the stable flying speed of the ink can be sufficiently secured.

In the ink composition, the gelatin is preferably alkali-treated gelatin.
Alkali-treated gelatin can be obtained by subjecting gelatin to alkali treatment such as lime treatment.

(Ink set)
The ink set of the present invention is composed of the above ink composition, or composed of the above ink composition and another ink composition.

(Inkjet recording method)
The ink jet recording method of the present invention is a method of forming an image by an ink jet method using the above ink set.

(Recorded material)
The recorded matter of the present invention can be obtained by recording by the above ink jet recording method.
The obtained recorded matter is excellent in image moisture resistance.

(Preparation of ink composition)
Each ink composition was prepared according to the following composition shown in Tables 1 and 2.
As magenta dye 1 in Tables 1 and 2, those shown below were used.

Further, as each gelatin in Table 1, the following alkali-treated gelatin manufactured by Nitta Gelatin Co., respectively was used.
GBL-100 Jelly strength: 100-140g (manufacturer published value)
GBL-150 Jelly strength: 135-165g (manufacturer published value)
GBL-200 Jelly strength: 185 to 215 g (manufacturer published value)
GBL-250 Jelly strength: 235-265g (manufacturer published value)

(Flight stability test)
By filling each ink composition into an ink cartridge for an ink jet printer and using an ink jet printer PM-A750 (manufactured by Seiko Epson Corporation, in a 25 ° C. environment, a small dot waveform), the distortion rate of the piezo element can be changed to thereby change the ink. Recording was performed on a recording medium by changing the flying speed of the droplets.
Here, when the ink droplet starts to fly or during the flight, the maximum flying speed of the ink droplet that does not become a multi-drop of 3 or more is set as the maximum stable flying speed (m / s). The lowest flying speed of the ink droplets that did not stall was recorded as the lowest stable flying speed (m / s). That is, the range of flying with two drops was determined as the stable range from the difference between the highest stable flying speed (a) and the lowest stable flying speed (b).

(Moisture resistance test)
Using an ink jet printer PM-A750 (manufactured by Seiko Epson Corporation), each ink composition is filled in a magenta dedicated cartridge (magenta chamber) of this printer, and an ink jet dedicated recording medium (photo paper crispier <high gloss> ( (Made by Seiko Epson Corporation))) Magenta-use patches of various concentrations are printed on top. The printed sample was dried at room temperature for 24 hours, and then left for 9 days in an environment of a temperature of 40 ° C. and a relative humidity of 85% RH, and bleeding of each patch was visually observed.
The scoring was graded as 5>4>3>2> 1 on the basis of 1 as the standard with no gelatin added ink.
These results are shown in Tables 3 and 4.

As shown in Tables 3 and 4, it was found that the ink compositions of the examples were superior in moisture resistance and flight stability compared to the ink compositions of the comparative examples.
Further, the moisture resistance of the ink compositions of Comparative Examples 2 to 7 and 13 could not be evaluated because sufficient flight stability could not be obtained and the printing quality necessary for the moisture resistance evaluation could not be ensured.

Claims (5)

  An ink composition comprising at least gelatin having a jelly strength of 215 g or less as an essential component and a gelatin content of 0.8% by weight or less.   The ink composition according to claim 1, wherein the gelatin is alkali-processed gelatin.   An ink set comprising the ink composition according to claim 1.   An ink jet recording method using the ink set according to claim 3.   A recorded matter obtained by the ink jet recording method according to claim 4.