Inkjet ink composition, method for manufacturing the inkjet ink composition and image forming method using the inkjet ink composition

a technology of inkjet ink and composition, which is applied in the field of composition, can solve the problems of poor water resistance of recorded images, blurred images when contacting water, and poor light resistance, and achieve good ph stability

Inactive Publication Date: 2005-04-28
RICOH KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0019] Accordingly, an object of the present invention is to provide a composition (particularly a pigment type inkjet ink composition), which has good pH stability even when preserved at a high temperature.

Problems solved by technology

However, these inkjet inks (hereinafter referred to as dye type inkjet inks) have the following drawbacks: (1) recorded images have so poor water resistance as to be blurred when contacting water; and (2) recorded images have poor light resistance such that when the recorded images are exposed to light, the color tones of the images change or the image density thereof decreases.
When the pigment dispersion for use in an inkjet ink includes pigment particles having a relatively large particle diameter, the nozzles from which the ink is to be discharged are clogged with the large pigment particles included in the resultant inkjet ink, resulting occurrence of a problem in that the ink is not discharged from the nozzles (hereinafter referred to as a clogging problem).
In addition, when large pigment particles are present in the inkjet ink, image qualities of the recorded images, such as clearness, resolution and color reproducibility (i.e., transparency) deteriorate.
However, both pigment type inkjet inks which use a pigment dispersion including a dispersant and pigment type inkjet inks which use a pigment dispersion including a self-dispersion pigment have a drawback in that the pH of the inks greatly changes (i.e., decreases) when the inks are preserved at 70° C. in a closed place.
If the degree of decrease in pH of an ink is large, a problem in that metal elements of an inkjet printer which contacts the inkjet ink and which are designed so as to be suitable for the original inkjet ink dissolve in or are corroded by the pH-changed inkjet ink occurs.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0093] The following components were mixed to prepare a pigment ink liquid (1) for use in a pigment type inkjet ink composition.

Formula of pigment ink liquid (1) for pigment typeinkjet ink compositionGlycerin80Diethylene glycol2402-pyrrolidone302-ethyl-1,3-hexanediol30Antiseptic (PROXEL LV(S), solid content of 20%)3Distilled water436Self-dispersion carbon black600(CAB-O-JET300 manufacturedby CABOT CORP., averageparticle diameter of136 nm and pigmentcontent of 15%by weight)

[0094] Then 80 parts of a 1% aqueous solution of lithium hydroxide (monohydrate) were added to the pigment ink liquid (1) drop by drop while the mixture was agitated to prepare an inkjet ink composition (1a) (i.e., a basic material containing pigment ink liquid (1)). The pH of the inkjet ink composition (1a) was 10.91.

[0095] The thus prepared inkjet ink composition (1a) was contained in a polyethylene container and then the container was sealed. The inkjet ink composition (1a) in the container was set in an oven...

example 2

[0102] The procedure for preparation of the inkjet ink composition (1a) in Example 1 was repeated except that the addition amount of the 1% aqueous solution of lithium hydroxide was changed from 80 parts to 110 parts. Thus an inkjet ink composition (2a) (i.e., a basic material containing pigment ink liquid) was prepared. The pH of the inkjet ink composition (2a) was 11.46.

[0103] The thus prepared inkjet ink composition (2a) was contained in a polyethylene container and then the container was sealed. The inkjet ink composition (2a) in the container was set in an oven heated at 80° C. to be subjected to a heat treatment. When the inkjet ink composition (2a) was heat-treated while the pH thereof was measured, the pH gradually decreased over a period of time. After the inkjet ink composition (2a) was subjected to the heat treatment for 16 days, the inkjet ink composition (2a) was taken out from the oven. The pH thereof was 8.36.

[0104] The heat-treated inkjet ink composition (2a) was t...

example 3

[0106] Twenty (20) parts of a 10% aqueous solution of sodium hydroxide were added drop by drop to the following pigment dispersion (1) while the mixture was agitated to prepare a basic material containing pigment dispersion (3a) (hereinafter referred to as a dispersion (3a)). The pH of the dispersion (3a) was 10.50.

Formula of pigment dispersion (1) for pigment typeinkjet ink compositionSelf-dispersion carbon black600(CAB-O-JET300manufactured byCABOT CORP., averageparticle diameter of136 nm and pigmentcontent of 15% by weight)

[0107] The thus prepared dispersion (3a) was contained in a polyethylene container and then the container was sealed. The dispersion (3a) in the container was set in an oven heated at 50° C. to be subjected to a heat treatment. When the pigment dispersion (3a) was heat-activated while the pH thereof was measured, the pH gradually decreased over a period of time. After the dispersion (3a) was subjected to the heat treatment for 5 days, the dispersion (3a) was t...

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Abstract

A method for manufacturing a composition including: mixing a basic material with a pigment dispersion including at least a pigment and water; and then subjecting the mixture of the basic material and pigment dispersion to a heat treatment. This composition is useful as an inkjet ink composition. An inkjet ink composition including at least pigment, water and a basic material, and has a pH of from 6.5 to 11.0 is also provided. An image forming method including discharging the composition from a nozzle to form an ink image on a receiving material is provided.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a composition and particularly to an inkjet ink composition for use in ink jet printing. In addition, the present invention relates to a method for manufacturing the composition, and to an image forming method using the composition. [0003] 2. Discussion of the Background [0004] As having been disclosed in published Japanese Patent Applications Nos. 63-51485, 63-56575 and 01-198671, inkjet inks, which are prepared by dissolving one or more water-soluble dyes in water or a mixture solvent including water and a water-soluble solvent and optionally adding an additive to the solution, have been mainly developed and used. However, these inkjet inks (hereinafter referred to as dye type inkjet inks) have the following drawbacks: [0005] (1) recorded images have so poor water resistance as to be blurred when contacting water; and [0006] (2) recorded images have poor light resistance such that ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C09C1/48C09C1/56C09D11/00
CPCC09C1/48C09C1/56Y10T428/24802C09D11/322C01P2004/62C09D11/30
Inventor TANIGUCHI, KEISHIHATADA, SHIGEO
Owner RICOH KK
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