JPH05105837A - Water-base pigment ink composition for ball-point pen - Google Patents

Abstract

PURPOSE:To prepare the title compsn. which does not rust a metallic chip and is excellent in storage stability by compounding a pigment, a water-sol. org. solvent, water, 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 a polyoxyethylene alkylphenyl ether-formaldehyde condensate 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 because the lipophilic part of the dispersant is strongly adsorbed by the pigment while the hydrophilic part interacts strongly with the ink solvent. Since free H<+> is scarcely present in the ink solvent, a metal chip can be used without being rusted, enabling good writing.

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. (For example, Japanese Patent Publication 55-18473, Japanese Patent Publication 57-3
However, these water-based inks for ballpoint pens have problems such as discoloration of handwriting after writing when exposed to sunlight for a long time, and bleeding and indecipherability when water is applied to the handwriting. 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, JP-B-55-35434)

[0003]

The above-described aqueous pigment ink composition for ball-point pen does not easily fade even after the handwriting after writing is exposed to sunlight for a long time, and the ink bleeds even when the handwriting is wet. There is no. 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 in the past (for example, Japanese Examined Patent Publication No. 55-34434), but when they are poured into an aqueous ballpoint pen having a metal tip, they have the drawbacks that the tip portion rusts or good writing is not possible. Was.

[0004]

The present invention provides a pigment dispersant which can stably disperse pigment particles in an ink solvent for a long period of time, and does not cause rust even if a metal chip is used. Good writing is possible. That is, in the aqueous 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 a polyoxyethylene alkylphenyl formaldehyde condensate. A water-based ink composition for a ballpoint pen. Hereinafter, the present invention will be described in detail.

As the pigment used in the aqueous pigment ink composition for a ballpoint pen of the present invention, all conventionally known organic pigments and inorganic pigments can be used, for example, azo type, phthalocyanine type,
Quinacridone series, Anthraquinone series, Chiokosazine series,
Indigo / thioindigo type, perinone / perylene type, iriindrenone type, titanium oxide type, cadmium type, carbon black type and the like. 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 amount of addition may be determined in consideration of these factors. The amount is usually 1 to 20% by weight, preferably 2 to 10% by weight, although it varies depending on the kind of the pigment used.

In the pigment dispersant used in the present invention, the hydrophilic group portion is a polyoxyethylene chain, and therefore, a pigment dispersion ink having a carboxy group in the hydrophilic group (for example, JP-B-55-35).
434) and the like, the release of H ⁺ into the solution is extremely small, and as a result, chains are not generated even when a metal tip is used. Water-soluble organic solvents are used as moisturizers, and include, for example, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, methyl cellosolve acetate, methyl carbitol, ethyl carbitol, butyl carbitol, and glycerin, or their derivatives. At least one water-soluble organic solvent selected from 1 to 50% by weight is added to the ink. 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, rust preventives, antiseptics, and defoamers can be added if necessary.

The water-based pigment ink for pole pens of the present invention has the above composition and composition. 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.

[0008]

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 the polyoxyethylene alkylphenyl formaldehyde condensate is strongly adsorbed on the pigment, and since its hydrophilic part is composed of polyoxyethylene chains, it is retained in the ink medium by hydrogen bonding, As a result, a strong interaction with the solvent is formed, so that the pigment content is stably retained in the ink solvent for a long period of time, while almost no free H ⁺ is present in the ink solvent, so that even when a metal chip is used. Good writing is possible without rusting.

[0009]

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 alkylphenyl formaldehyde condensate 6 parts Rust preventive agent 0.1 part Water 53.9 parts After pulverizing the above-mentioned components by a ball mill for 12 hours, centrifuging Coarse particles that were not crushed in a container at 4000 rpm for 30 minutes were removed to obtain a black water-based pigment ink for ballpoint pens. Example-2 Reiki red 9 parts Ethylene glycol 20 parts Glycerin 10 parts Polyoxyethylene alkylphenyl formaldehyde condensate 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 Then, coarse particles which were not crushed in a centrifuge 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 alkylphenyl formaldehyde condensate 5.5 parts Rust preventive agent 0.1 parts Water 53.9 parts After pulverizing the above-mentioned compounding components with a ball mill for 12 hours Then, coarse particles not crushed in a centrifuge at 4000 rpm for 30 minutes were removed to obtain a blue water-based pigment ink for ballpoint pens.

[0010]

EFFECTS OF THE INVENTION About 1 g of the water-based pigment ink for ballpoint pens obtained in Examples 1 to 3 was filled in a water-based ballpoint pen having metal chips and a storage test was conducted in an atmosphere of 50 ° C. However, even after 2 years, I was able to write without any problems just as it was immediately after the production.

Claims (1)

[Claims] 1. At least a pigment, a water-soluble organic solvent,
An aqueous pigment ink composition for a ball-point pen, comprising water and a pigment dispersant, wherein the pigment dispersant is a polyoxyethylene alkylphenyl formaldehyde condensate.