JPH05105836A - Water-base pigment ink composition for ball-point pen - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in storage stability and free from agglomeration or precipitaion of a pigment even when long stored by compounding the pigment, water, a water-sol. org. solvent, and a specific pigment dispersant as essential components. CONSTITUTION:A pigment, an ink solvent comprising water and a water-sol. org. solvent, and a pigment dispersant comprising polyoxyethylene phytosterol and/or polyoxyethylene phytostanol are compounded as essential components to give the title compsn., which is free from agglomeration or precipitation of the pigment, causing no writing trouble. The pigment dispersion in the ink solvent is long stable probably because the lipophilic part of the dispersant is strongly adsorbed by the pigment while the hydrophilic part interacts with the ink solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based pigment ink for ballpoint pens, and more specifically, a water-based pigment ink for ballpoint pens, which is excellent in long-term storage stability without causing defective writing due to pigment aggregation and sedimentation even after long-term storage. The present invention relates to a pigment ink composition.

[0002]

2. Description of the Related Art Conventionally, water-based inks for ballpoint pens have been composed of various dyes as colorants, water-soluble organic solvents as evaporation inhibitors, other water, rust preventives, preservatives and the like. However, these water-based inks for ball-point pens have problems such that the handwriting after writing is discolored when exposed to sunlight for a long time, and when the handwriting is exposed to water, it becomes bleeding and becomes unreadable. (For example, Japanese Patent Publication 57-31596, Japanese Patent Publication 55-
18473) In recent years, as a method for solving these problems, an aqueous pigment ink composition for a ballpoint pen, which uses a pigment instead of a dye as a colorant, has been proposed. (For example, Japanese Patent Publication No. 55-35434)

[0003]

The above aqueous pigment ink composition for ballpoint pens does not easily fade even when the handwriting after writing is exposed to sunlight for a long time, and the ink does not bleed when the handwriting is wet. . However, since the pigment is insoluble in the ink solvent, it must be stably dispersed in the ink solvent. Various pigment dispersants have been proposed so far, but none of them have satisfactory long-term storage stability when injected into an aqueous ballpoint pen having a metal tip.

[0004]

SUMMARY OF THE INVENTION The present invention provides a pigment dispersant capable of stably dispersing pigment particles in an ink solvent for a long period of time. That is, in the water based pigment ink composition for a ballpoint pen, which is composed of at least a pigment, a pigment dispersant, a water-soluble organic solvent, and water, the pigment dispersant is polyoxyethylene phytosterol and / or polyoxyethylene phytostanol. A water-based ink composition for a ballpoint pen, which is characterized by the fact that it is present. Hereinafter, the present invention will be described in detail. The pigment used in the water-based pigment ink composition for a ballpoint pen of the present invention can be all conventionally known organic pigments and inorganic pigments, for example,
Examples include azo type, phthalocyanine type, quinacridone type, anthraquinone type, quinocosadin type, indigo / thioindigo type, perinone / perylene type, iriindrenone type, titanium oxide type, cadmium type and carbon black type. When the content in the ink is low, the pigment dispersion is insufficient, and when the content is high, the viscosity of the ink is high, and the ink is blurred during writing. The addition amount may be determined in consideration of these factors. The amount is usually 1 to 20% by weight, preferably 2 to 10% by weight, depending on the type of pigment used. Further, the water-soluble organic solvent is used as a moisturizing agent. For example, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, methyl cellosolve acetate, methyl carbitol, ethyl carbitol, butyl carbitol, glycerin, or their derivatives can be used. At least one water-soluble organic solvent selected from the above is added to the ink in an amount of 1 to 50% by weight. Further, the water used in the present invention is preferably distilled water, but ion-exchanged water or tap water can also be used. In addition, if necessary, rust preventive, antiseptic,
An antifoaming agent can also be added. The water-based pigment ink for pole pens of the present invention has the above composition and formulation. As a method for producing the same, various conventionally known methods can be adopted. For example, after mixing the above-mentioned composition components, they are mixed and crushed by a known crusher such as a ball mill, a homomixer, a sand mill and a speed line mill, and then crushed by a centrifuge or the like. A typical method is to remove the coarse pigment particles that have not been formed.

[0005]

The water-based pigment ink for ballpoint pens of the present invention obtained as described above does not aggregate or settle the pigment component even when stored for a long period of time. This is because the lipophilic part of polyoxyethylene phytosterol and / or polyoxyethylene phytostanol is strongly adsorbed on the pigment, and the hydrophilic part interacts with the ink solvent, so that the pigment component remains in the ink solvent for a long time. It is considered to be stably maintained.

[0006]

EXAMPLES Next, the present invention will be described in detail with reference to Examples. In the examples, "parts" means parts by weight. Example-1 Carbon black 10 parts Ethylene glycol 20 parts Glycerin 10 parts Polyoxyethylene phytosterol 6 parts Rust preventive agent 0.1 part Water 53.9 parts After crushing the above-mentioned compounding ingredients for 12 hours with a ball mill, it is 4000 rpm in a centrifuge. The coarse particles that were not crushed in 30 minutes were removed to obtain a black aqueous pigment ink for ballpoint pens. Example-2 Reiki red 9 parts Ethylene glycol 20 parts Glycerin 10 parts Polyoxyethylene phytostanol 5.5 parts Rust preventive agent 0.1 parts Water 53.9 parts After crushing the above-mentioned components by a ball mill for 12 hours, centrifuge After that, coarse particles which were not crushed at 4000 rpm for 30 minutes were removed to obtain a red water-based pigment ink for ballpoint pens. Example-3 Cyanine blue 9 parts Ethylene glycol 20 parts Glycerin 10 parts Polyoxyethylene phytostanol 5.5 parts Rust preventive agent 0.1 parts Water 53.9 parts After pulverizing the above-mentioned components by a ball mill for 12 hours, centrifuge After that, coarse particles which were not crushed at 4000 rpm for 30 minutes were removed to obtain a blue aqueous pigment ink for ballpoint pens.

[0007]

[Effect of the invention] About 1 g of the water-based pigment ink for ball-point pens obtained in Examples 1 to 3 was filled in a water-based ball-point pen of metal tip (for example, stainless steel, nickel silver, etc.), and a storage test was conducted in an atmosphere of 50 ° C. All of the inks of Examples 1 to 3 could be written without problems even after 2 years, just as immediately after production.

Claims (1)

[Claims] 1. At least a pigment, a water-soluble organic solvent,
An aqueous pigment ink composition for a ballpoint pen, comprising water and a pigment dispersant, wherein the pigment dispersant is polyoxyethylene phytosterol and / or polyoxyethylene phytostanol. ..